JP5064032B2 - Method for producing water-absorbent resin granulated product and water-absorbent resin granulated product - Google Patents
Method for producing water-absorbent resin granulated product and water-absorbent resin granulated product Download PDFInfo
- Publication number
- JP5064032B2 JP5064032B2 JP2006524159A JP2006524159A JP5064032B2 JP 5064032 B2 JP5064032 B2 JP 5064032B2 JP 2006524159 A JP2006524159 A JP 2006524159A JP 2006524159 A JP2006524159 A JP 2006524159A JP 5064032 B2 JP5064032 B2 JP 5064032B2
- Authority
- JP
- Japan
- Prior art keywords
- water
- absorbent resin
- weight
- particles
- granulated product
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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- 239000007788 liquid Substances 0.000 claims description 181
- 230000002745 absorbent Effects 0.000 claims description 180
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- 238000000034 method Methods 0.000 claims description 121
- 239000000203 mixture Substances 0.000 claims description 102
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- 238000010438 heat treatment Methods 0.000 claims description 36
- 239000000463 material Substances 0.000 claims description 36
- 238000004132 cross linking Methods 0.000 claims description 25
- 238000011282 treatment Methods 0.000 claims description 20
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- 239000004408 titanium dioxide Substances 0.000 description 1
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- BPSIOYPQMFLKFR-UHFFFAOYSA-N trimethoxy-[3-(oxiran-2-ylmethoxy)propyl]silane Chemical compound CO[Si](OC)(OC)CCCOCC1CO1 BPSIOYPQMFLKFR-UHFFFAOYSA-N 0.000 description 1
- YFHICDDUDORKJB-UHFFFAOYSA-N trimethylene carbonate Chemical compound O=C1OCCCO1 YFHICDDUDORKJB-UHFFFAOYSA-N 0.000 description 1
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- NLVXSWCKKBEXTG-UHFFFAOYSA-N vinylsulfonic acid Chemical compound OS(=O)(=O)C=C NLVXSWCKKBEXTG-UHFFFAOYSA-N 0.000 description 1
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- 229960001763 zinc sulfate Drugs 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
- DUNKXUFBGCUVQW-UHFFFAOYSA-J zirconium tetrachloride Chemical compound Cl[Zr](Cl)(Cl)Cl DUNKXUFBGCUVQW-UHFFFAOYSA-J 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J3/00—Processes of treating or compounding macromolecular substances
- C08J3/12—Powdering or granulating
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2300/00—Characterised by the use of unspecified polymers
- C08J2300/14—Water soluble or water swellable polymers, e.g. aqueous gels
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2333/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Derivatives of such polymers
- C08J2333/04—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Derivatives of such polymers esters
- C08J2333/06—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Derivatives of such polymers esters of esters containing only carbon, hydrogen, and oxygen, the oxygen atom being present only as part of the carboxyl radical
- C08J2333/08—Homopolymers or copolymers of acrylic acid esters
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- Polymers & Plastics (AREA)
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- Solid-Sorbent Or Filter-Aiding Compositions (AREA)
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Description
本発明は、吸水性樹脂造粒物の製造方法および吸水性樹脂造粒物に関するものである。 The present invention relates to a method for producing a water absorbent resin granulated product and a water absorbent resin granulated product.
具体的には、本発明は、吸水性樹脂を主成分とする吸水性樹脂造粒物の製造方法に関するものである。さらに詳しくは、紙オムツ(使い捨てオムツ)や生理用ナプキン、いわゆる失禁パッド等の衛生材料や廃液固化剤、止水剤等に好適に用いられる吸水性樹脂造粒物であって、微粉末が少なく高い造粒強度を有する吸水性樹脂造粒物の製造方法に関するものである。 Specifically, the present invention relates to a method for producing a water-absorbent resin granulated product containing a water-absorbent resin as a main component. More specifically, it is a water-absorbent resin granulated material suitably used for sanitary materials such as paper diapers (disposable diapers), sanitary napkins, so-called incontinence pads, waste liquid solidifying agents, water-stopping agents, etc. The present invention relates to a method for producing a water-absorbent resin granulated product having high granulation strength.
また、特に、吸水性樹脂粒子と水性液を混合し、さらに微粒子を混合することにより、効率よく吸水性樹脂造粒物を製造する方法に関する。 In particular, the present invention relates to a method for efficiently producing a water-absorbent resin granulated product by mixing water-absorbent resin particles and an aqueous liquid and further mixing fine particles.
近年、紙オムツや生理用ナプキン、いわゆる失禁パッド等(オムツ)の衛生材料には、体液を吸収させることを目的とする吸水剤として、吸水性樹脂が幅広く利用されている。また、吸水性樹脂は保水剤、土壌改良剤などの農園芸用品等、種々の製品にも広く用いられている。 In recent years, water-absorbing resins are widely used as hygroscopic materials for the purpose of absorbing body fluids in sanitary materials such as paper diapers and sanitary napkins, so-called incontinence pads (diapers). Water-absorbing resins are also widely used in various products such as agricultural and horticultural supplies such as water retention agents and soil conditioners.
かかる吸水性樹脂が備えるべき特性としては、体液等の水性液体に接した際の優れた吸収量や吸収速度、通液性、膨潤ゲルのゲル強度、水性液体を含んだ基材から水を吸い上げる吸引力等が挙げられる。しかしながら、これらの諸特性間の関係は必ずしも正の相関関係を示さず、例えば、吸収倍率の高いものほど通液性、ゲル強度及び吸収速度等の物性は低下してしまう。 Properties that such water-absorbent resins should have include excellent absorption amount and absorption rate when in contact with aqueous liquids such as body fluids, liquid permeability, gel strength of swollen gel, and water suction from a substrate containing aqueous liquid Examples include suction force. However, the relationship between these characteristics does not necessarily show a positive correlation. For example, the higher the absorption ratio, the lower the physical properties such as liquid permeability, gel strength, and absorption rate.
このような、吸水性樹脂の吸水諸特性をバランス良く改良する方法として吸水性樹脂の表面近傍を架橋する技術(表面架橋処理)が知られており、これまでに様々な方法(例えば、下記の特許文献1〜8)が開示されている。 As a method for improving the water absorption characteristics of the water absorbent resin in a well-balanced manner, a technique for cross-linking the vicinity of the surface of the water absorbent resin (surface crosslinking treatment) is known, and various methods (for example, the following) Patent Documents 1 to 8) are disclosed.
一方、一般的に、吸水性樹脂は、150μm未満の粒子径を有する粉末(微粉末)の含有量が少ない程好ましい。かかる微粉末は、おむつなどの吸収物品中でも目詰まりによって通液性が低下する要因となる。また、取り扱い時の粉塵やおむつの製造時のロスという問題を有している。このため、微粉末の少ない吸水性樹脂が切望されている。 On the other hand, in general, the water-absorbent resin is more preferable as the content of the powder (fine powder) having a particle diameter of less than 150 μm is small. Such fine powder becomes a factor that lowers liquid permeability due to clogging even in absorbent articles such as diapers. In addition, there is a problem of dust during handling and loss during manufacturing of the diaper. For this reason, a water-absorbing resin with less fine powder is desired.
従来、微粉末の少ない吸水性樹脂の製造方法としては、(1)重合や粉砕の度合いを最適化して粒度を調整する方法、および、(2)発生した微粉末を、篩や気流等により分級、除去する方法が知られている。しかしながら、上記(1)の方法でも、製造工程中に、数%〜数10%といった多量の微粉末が発生する。(2)の方法で発生した微粉末を廃棄することは、収率を大きく低下させると共に、廃棄コストの面からも不利となる。 Conventionally, as a method for producing a water-absorbent resin with a small amount of fine powder, (1) a method of adjusting the particle size by optimizing the degree of polymerization and pulverization, and (2) the generated fine powder is classified by a sieve or an air flow. The method of removing is known. However, even in the method (1), a large amount of fine powder such as several percent to several tens of percent is generated during the production process. Discarding the fine powder generated by the method (2) greatly reduces the yield and is disadvantageous in terms of disposal cost.
そこで、吸水性樹脂の製造工程で必然的に発生してしまう微粉末を造粒ないし再生することで上記の問題を解決しようとする提案が種々なされている。例えば、造粒以外の手法として、例えば特許文献9〜11では、微粉末を重合ゲル(あるいは粘度の高い物質)に混合して利用する方法を提案している。しかし、これらの方法では十分に微粉末量を減少することはできていない。 Therefore, various proposals have been made to solve the above problem by granulating or regenerating fine powder that is inevitably generated in the production process of the water absorbent resin. For example, as methods other than granulation, for example, Patent Documents 9 to 11 propose a method in which fine powder is mixed with a polymer gel (or a substance having a high viscosity) and used. However, these methods cannot sufficiently reduce the amount of fine powder.
また、特許文献12〜13では微粉末と水とを混合することによる造粒方法の提案を行っている。これらの方法は、微粉末の造粒割合は高いものの、得られた造粒物の微粉末量は十分に減少したものになっていない。 Patent Documents 12 to 13 propose a granulation method by mixing fine powder and water. In these methods, although the granulation ratio of the fine powder is high, the amount of fine powder in the obtained granulated product is not sufficiently reduced.
また、特許文献14〜17では混合助剤である無機塩化合物、水不溶性無機微粉末、高分子化合物、金属イオン含有化合物などの存在下、吸水性樹脂と水性液を混合し造粒する方法が提案されている。これらの方法は、混合助剤を使用している為に、一般に、製造コストがアップする問題や、さらに水不溶性無機微粉末による粉塵の発生や、得られる吸水性樹脂の吸収特性を低下させるという問題を有している。 In Patent Documents 14 to 17, a method of mixing and granulating a water-absorbent resin and an aqueous liquid in the presence of an inorganic salt compound, a water-insoluble inorganic fine powder, a polymer compound, a metal ion-containing compound, or the like, which is a mixing aid. Proposed. Since these methods use mixing aids, in general, the problem of increased production costs, generation of dust due to water-insoluble inorganic fine powder, and the absorption characteristics of the resulting water-absorbent resin are said to be reduced. Have a problem.
さらに、特許文献12において、吸水性樹脂粉末の造粒により微粉末の減少がなされても、吸水性樹脂の搬送工程や最終製品(例えば紙おむつなど)への加工工程で造粒粒子が破壊(造粒粒子破壊)されて、微粉末の再生が起きることにより、吸収速度の低下や、不純物である水可溶分が増加したり、加圧下の吸収倍率が低下するなどの物性低下が見られる場合があることが指摘されており、造粒物には高い造粒強度が必要であることが示唆されている。 Further, in Patent Document 12, even if the fine powder is reduced by granulating the water-absorbent resin powder, the granulated particles are destroyed (granulated) in the process of transporting the water-absorbent resin and processing the final product (for example, a paper diaper). When the powder is regenerated and the fine powder is regenerated, the absorption rate decreases, the water-soluble content of impurities increases, or the physical properties such as the absorption capacity under pressure decrease. It is suggested that there is a need for high granulation strength in the granulated product.
また、上記吸水性樹脂の物性に影響を与えるファクターの一つに粒径があり、これらの製品に要求される種々の特性を満たすため、造粒によって吸水性樹脂の粒径を調整することは非常に重要である。 In addition, one of the factors affecting the physical properties of the water-absorbent resin is the particle size, and in order to satisfy various properties required for these products, adjusting the particle size of the water-absorbent resin by granulation is not possible. Very important.
造粒とは複数の粒子を凝集させ、一定粒径の集合体を形成させることをいい、吸水性樹脂を造粒する技術はこれまでに多数検討されているが、殆どの場合、水性液(水、金属塩水溶液など)等の添加剤を吸水性樹脂に添加し、攪拌混合することにより達成されている。一方、一般的に、粒子径200μm未満の粒子を主成分とする吸水性樹脂粒子(以下、微粉という)、特に150μm未満の粒子径を主成分とする吸水性樹脂粒子の含有量が少ない程好ましい。 Granulation means agglomeration of a plurality of particles to form an aggregate having a constant particle diameter. Many techniques for granulating a water-absorbing resin have been studied so far, but in most cases, an aqueous liquid ( This is achieved by adding an additive such as water or an aqueous metal salt solution to the water-absorbent resin and stirring and mixing. On the other hand, generally, the smaller the content of the water-absorbent resin particles (hereinafter referred to as fine powder) whose main component is particles having a particle diameter of less than 200 μm, in particular, the water-absorbent resin particles whose main component is a particle diameter of less than 150 μm is preferable. .
かかる微粉は、オムツなどの吸収物品中でも目詰まりによって通液性が低下する要因となる。また、取り扱い時の粉塵やおむつの製造時のロスという問題を有している。このため、微粉の少ない吸水性樹脂が切望されている。 Such fine powder becomes a factor that decreases liquid permeability due to clogging even in an absorbent article such as a diaper. In addition, there is a problem of dust during handling and loss during manufacturing of the diaper. For this reason, a water-absorbent resin with less fine powder is desired.
そこで、吸水性樹脂の製造工程で必然的に発生してしまう微粉を造粒ないし再生することで上記の問題を解決しようとする提案が種々なされている。造粒以外の手段としては、例えば特許文献9、10、14では微粉と水や含水ゲルとを混合することにより上記微粉をゲル化した後、得られたゲル化物を粉砕後、乾燥させることで大きな粒子に再生する方法が提案されている。しかしこれらの方法は、微粉は一度ゲル化物とし、乾燥後、粉砕等の工程を行っており、得られた吸水性樹脂粒子は特に微粉が減少したものになっていない。 Therefore, various proposals have been made to solve the above-mentioned problems by granulating or regenerating fine powder that is inevitably generated in the production process of the water absorbent resin. As means other than granulation, for example, in Patent Documents 9, 10, and 14, the above fine powder is gelled by mixing the fine powder with water or a water-containing gel, and then the obtained gelled product is pulverized and dried. A method for regenerating large particles has been proposed. However, in these methods, the fine powder is once made into a gelled product, and after drying, a process such as pulverization is performed, and the obtained water-absorbent resin particles are not particularly reduced in fine powder.
水性液の添加量に関しては、吸水性樹脂に対して少量の水性液(5%〜10重量%以下)または、多量の水性液(100%以上)を添加するケースが殆どである。この理由としては、吸水性樹脂含水物とした場合の固形分が60〜80%(水性液の量が20〜40%)であるときに、吸水性樹脂含水物の接着性が最も高くなり塊状となる性質を有していることが挙げられる。本特許の権利範囲とは何ら関係ないが、この接着力は、吸水性樹脂の原料でもあるポリアクリル酸(塩)の水素結合に由来するものと推測され、この接着力によって造粒粒子が形成されるが、過大な接着力により塊状物となってしまう。 As for the amount of aqueous liquid added, most of the cases are adding a small amount of aqueous liquid (5% to 10% by weight or less) or a large amount of aqueous liquid (100% or more) to the water-absorbent resin. The reason for this is that when the water content of the water-absorbing resin hydrate is 60 to 80% (the amount of the aqueous liquid is 20 to 40%), the water-absorbing resin hydrate has the highest adhesiveness and is a lump. It has the property to become. Although it has nothing to do with the scope of rights of this patent, it is speculated that this adhesive force is derived from hydrogen bonding of polyacrylic acid (salt), which is also the raw material of the water-absorbent resin, and granulated particles are formed by this adhesive force. However, it becomes a lump by excessive adhesive force.
一方、水性液を添加した吸水性樹脂(吸水性樹脂含水物)は、通常、流動性に乏しく、吸水性樹脂含水物全体が凝集し、塊状になりやすい傾向にある。従って、流動性を得る為には、吸水性樹脂含水物を乾燥等することにより、吸水性樹脂含水物の表面近傍に存在する水分(この水分の存在によって、吸水性樹脂含水物は柔軟化し、凝集しやすくなっている)を吸水性樹脂含水物から系外に飛散(蒸発・乾燥)、または表面の水分を吸水性樹脂含水物内部に拡散させること(硬化)が必要である。 On the other hand, a water-absorbent resin (water-absorbent resin hydrate) to which an aqueous liquid is added usually has poor fluidity, and the entire water-absorbent resin hydrate tends to aggregate and tend to be agglomerated. Therefore, in order to obtain fluidity, by drying the water-absorbing resin water-containing material, moisture existing near the surface of the water-absorbing resin water-containing material (the presence of this water softens the water-absorbing resin water-containing material, It is necessary to scatter (evaporate and dry) the water-absorbent resin hydrated product from the water-absorbing resin hydrated product, or to diffuse the surface moisture into the water-absorbent resin hydrated product (cured).
また、水性液を添加するだけでなく、さらに無機粒子を添加して吸水性樹脂を製造する技術も開示されている。例えば、吸水性樹脂に適度な強度を付与するとともに造粒物の吸水速度向上を図るため、エチレン−アクリル酸共重合体と無機粒子とを添加後、水を添加して吸水性樹脂を製造する方法(例えば特許文献19)や、吸湿下でのブロッキング性改善を図るため、水性液と無機粉末の分散液とを添加して吸水性樹脂を製造する方法(例えば特許文献20)等が開示されている。
上記のように吸水性樹脂の微粉末を少なくする改良は多数試みられている。しかし、簡便でかつ、微粉末量を著しく少なくする安定した造粒方法は見られない。 Many attempts have been made to reduce the fine powder of the water-absorbent resin as described above. However, there is no simple granulation method that is simple and significantly reduces the amount of fine powder.
また、水性液を添加し、攪拌混合する従来の方法では、強力な接着力による塊状物の形成、添加する水性液の不均一な混合などが生じるため、次第に攪拌混合しにくくなり、塊状体(例えば、直径数cm〜数10cm以上)が形成されてしまう。仮に、これら接着性の高い吸水性樹脂含水物の塊状体を用いて、粒径の揃った造粒粒子を製造するには、より強い撹拌力と解砕力、長い撹拌時間(造粒時間)が必要であり、造粒粒子(例えば1mm〜0.15mm)の製造コスト上昇や塊状体を潰す必要性に伴う物性低下に繋がると推察される。 In addition, in the conventional method of adding an aqueous liquid and stirring and mixing, formation of a lump with strong adhesive force, non-uniform mixing of the added aqueous liquid, and the like, gradually becoming difficult to stir and mix. For example, a diameter of several centimeters to several tens of centimeters or more) is formed. To produce granulated particles with a uniform particle size using these highly adhesive water-absorbent resin hydrates, stronger agitation and crushing power and longer agitation time (granulation time) are required. It is speculated that this leads to an increase in the production cost of the granulated particles (for example, 1 mm to 0.15 mm) and a decrease in physical properties accompanying the necessity of crushing the lump.
また、水性液を添加し、攪拌混合する従来の方法で得られた吸水性樹脂含水物は上述のように塊状体になり易いので、非常に乾燥しにくい。塊状体が形成されると、乾燥等の工程において、吸水性樹脂含水物への熱伝導効率が悪くなるだけでなく、水分の移動を妨げる傾向があり、乾燥等の工程において、過剰な熱エネルギーが必要となる上、乾燥等が不均一になる。その結果、物性低下など効率のよい造粒を行うことはできない。 Moreover, since the water-absorbing resin hydrate obtained by the conventional method of adding an aqueous liquid and stirring and mixing is likely to become a lump as described above, it is very difficult to dry. When a lump is formed, not only the heat conduction efficiency to the water-absorbing resin hydrated product is deteriorated in a process such as drying, but also there is a tendency to prevent the movement of moisture. In addition, drying and the like are not uniform. As a result, efficient granulation such as physical property degradation cannot be performed.
すなわち、従来の技術では吸水性樹脂含水物の塊状体形成を防ぐことができないため、吸水性樹脂含水物を効率良く乾燥または硬化することはできず、結果として、粒径の揃った、流動性を有する造粒粒子を効率よく製造することはできないという問題がある。 That is, since the conventional technology cannot prevent the formation of a mass of the water-absorbent resin hydrate, the water-absorbent resin hydrate cannot be efficiently dried or cured. There is a problem that it is not possible to efficiently produce granulated particles having slag.
また、特許文献19には、吸水性樹脂に無機粉末、エチレン−アクリル酸共重合体および水を混合するに当たって水を後から添加し、乾燥することにより、高い粒子強度と適度の粒径を有し、かつ粒度分布の狭い造粒物を収率よく得ることができる旨が記載されているが、本技術は、吸水性樹脂含水物の塊状体形成を防ぎ、効率良い乾燥または硬化を可能とすることを目的としたものではない。 Patent Document 19 discloses that water mixing is performed by adding water after mixing inorganic powder, an ethylene-acrylic acid copolymer, and water in a water-absorbing resin, and then drying to obtain high particle strength and an appropriate particle size. However, it is described that a granulated product having a narrow particle size distribution can be obtained with a high yield, but this technology prevents the formation of a mass of the water-absorbing resin water-containing material and enables efficient drying or curing. It is not intended to do.
さらに、特許文献20には、吸水性樹脂、水性液、および無機粉末の分散液を混合することにより、吸湿下でのブロッキング性に優れた吸水剤を得る技術が記載されているが、特許文献20も、吸水性樹脂含水物の塊状体形成を防ぎ、効率良い乾燥または硬化を可能とすることを目的としたものではない。また、特許文献20に記載の技術は、吸水性樹脂、水性液、および無機粉末の分散液を混合後、乾燥等を行うものではないので、流動性を有する造粒粒子を十分に得ることはできない。 Furthermore, Patent Document 20 describes a technique for obtaining a water-absorbing agent having excellent blocking properties under moisture absorption by mixing a water-absorbing resin, an aqueous liquid, and a dispersion of inorganic powder. No. 20 is not intended to prevent the formation of a mass of the water-absorbing resin hydrate, and to enable efficient drying or curing. Moreover, since the technique described in Patent Document 20 does not perform drying or the like after mixing the water-absorbent resin, the aqueous liquid, and the dispersion of the inorganic powder, it is not possible to sufficiently obtain granulated particles having fluidity. Can not.
本発明は、上記従来の問題点に鑑みなされたものであって、その目的は、前記した吸水性樹脂の微粉末に起因する種々の問題を解決し、高い造粒強度を有する上、造粒による物性低下もない、微粉末量の少ない吸水性樹脂造粒物の製造方法、または、吸水性樹脂含水物の塊状体形成を防ぎ、効率の良い乾燥または硬化を可能とする吸水性樹脂造粒物の製造方法および吸水性樹脂造粒物を提供することである。 The present invention has been made in view of the above-described conventional problems, and its object is to solve various problems caused by the fine powder of the water-absorbent resin described above, and to have a high granulation strength and granulation. Water-absorbent resin granulated product that does not deteriorate in physical properties due to the production of the water-absorbent resin granulated product with a small amount of fine powder, or that prevents the formation of a mass of the water-absorbent resin water-containing product and enables efficient drying or curing It is providing the manufacturing method of a thing, and a water absorbent resin granulated material.
本発明の粒子状吸水剤の製造方法は、重量平均粒子径が200μm未満である第一の吸水性樹脂粒子と水性液とを混合し吸水性樹脂含水物を得る工程(a)と、該吸水性樹脂含水物に、重量平均粒子径が200〜800μmである第二の吸水性樹脂粒子を混合する工程(b)とを含むことを特徴としている。 The method for producing a particulate water-absorbing agent of the present invention comprises a step (a) of mixing a first water-absorbing resin particle having a weight average particle diameter of less than 200 μm and an aqueous liquid to obtain a water-absorbing resin hydrate, and the water-absorbing agent. sexual resin hydrate is characterized by a weight average particle diameter and the step (b) mixing the second water-absorbing resin particles child is 200~800Myuemu.
また、本発明の吸水性樹脂造粒物の製造方法は、上記の吸水性樹脂含水物の含水率が20重量%以上99重量%以下であることが好ましい。 A method of manufacturing a water absorbing resin granulation product of the present invention, it is preferable moisture content of the upper Symbol absorbent resin hydrate of 20 wt% to 99 wt% or less.
また、本発明の吸水性樹脂造粒物の製造方法は、前記水性液を含む第一の吸水性樹脂粒子が含水ゲル状物であることが好ましい。 In the method for producing a water-absorbent resin granulated product of the present invention, it is preferable that the first water-absorbent resin particle containing the aqueous liquid is a hydrogel.
また、本発明の吸水性樹脂造粒物の製造方法は、第一の吸水性樹脂粒子が表面架橋処理されていることが好ましい。 In the method for producing a water-absorbent resin granulated product of the present invention, the first water-absorbent resin particles are preferably subjected to surface cross-linking treatment.
また、本発明の吸水性樹脂造粒物の製造方法は、前記水性液を含む第一の吸水性樹脂粒子および第二の吸水性樹脂粒子の混合物を加熱乾燥する工程(c)を含むことが好ましい。 Moreover, the manufacturing method of the water absorbent resin granulated product of the present invention includes a step (c) of heating and drying a mixture of the first water absorbent resin particles and the second water absorbent resin particles containing the aqueous liquid. preferable.
また、本発明の吸水性樹脂造粒物の製造方法は、第一の吸水性樹脂粒子と第二の吸水性樹脂粒子の重量比が1/99〜50/50の範囲であることが好ましい。 Moreover, it is preferable that the weight ratio of the 1st water absorbing resin particle and the 2nd water absorbing resin particle is the range of the manufacturing method of the water absorbing resin granulated material of this invention in the range of 1 / 99-50 / 50.
上記構成によれば、水性液を吸水性樹脂粒子に対して十分に分布させることができるので、吸水性樹脂粒子に対して十分な接着力を供することができ、最適な強度の造粒物を得ることができる。したがって、水性液混合工程において吸水性樹脂粒子の造粒を円滑に進行させることができる。 According to the above configuration, since the aqueous liquid can be sufficiently distributed to the water absorbent resin particles, it is possible to provide a sufficient adhesive force to the water absorbent resin particles, and to obtain a granulated product having an optimum strength. Obtainable. Therefore, granulation of the water-absorbing resin particles can proceed smoothly in the aqueous liquid mixing step.
また、本発明の吸水性樹脂造粒物の製造方法は、前記水性液を含む第一の吸水性樹脂粒子および第二の吸水性樹脂粒子の混合物ないしその乾燥物を、分級する工程(d)を含むことが好ましい。 The method for producing a water-absorbent resin granulated product of the present invention includes a step (d) of classifying a mixture of the first water-absorbent resin particles and the second water-absorbent resin particles containing the aqueous liquid or a dried product thereof. It is preferable to contain.
また、本発明の吸水性樹脂造粒物の製造方法は、得られる吸水性樹脂造粒物が第一の吸水性樹脂粒子と第二の吸水性樹脂粒子との造粒物であることが好ましい。 In the method for producing a water-absorbent resin granulated product of the present invention, the obtained water-absorbent resin granulated product is preferably a granulated product of first water-absorbent resin particles and second water-absorbent resin particles. .
また、本発明の吸水性樹脂造粒物の製造方法は、第一および第二の吸水性樹脂粒子がポリアクリル酸系吸水性樹脂であることがこのましい。 In the method for producing a water-absorbent resin granulated product of the present invention, the first and second water-absorbent resin particles are preferably polyacrylic acid-based water-absorbent resins.
本発明の吸水性樹脂造粒物は特定の混合工程を経て得られることで、吸水性樹脂の微粉末に起因する種々の問題を解決し、高い造粒強度を有する上、造粒による物性低下も小さい、微粉末量が非常に低減されたものとなる。 The water-absorbent resin granulated product of the present invention is obtained through a specific mixing step, thereby solving various problems caused by the fine powder of the water-absorbent resin, having high granulation strength, and lowering physical properties due to granulation. Also, the amount of fine powder is greatly reduced.
本発明に係る吸水性樹脂造粒物は、本発明に係る吸水性樹脂造粒物の製造方法で得られる吸水性樹脂造粒物であって、水分を吸水性樹脂造粒物の全量100重量部に対して5重量部以上20重量部以下、含み、(1)0.90重量%の塩化ナトリウム水溶液に対する無加圧下吸収倍率が27g/g以上であり、(2)0.90重量%の塩化ナトリウム水溶液に対する1.9kPaでの加圧下吸収倍率が20g/g以上であり、(3)0.90重量%の塩化ナトリウム水溶液に対する4.8kPaでの加圧下吸収倍率が10g/g以上であり、(4)0.90重量%の塩化ナトリウム水溶液に対する吸収速度が20秒以上50秒以下であり、(5)吸水性樹脂造粒物100重量部に対し、目開き150μmのJIS標準篩を通過する粒子が0重量部以上5重量部以下であることを特徴としている。 The water-absorbent resin granulated product according to the present invention is a water-absorbent resin granulated product obtained by the method for producing a water-absorbent resin granulated product according to the present invention. 20 parts by weight or less in 5 parts by weight or more with respect to parts, seen including, (at 1) absorption capacity without load for 0.90 wt% sodium chloride aqueous solution 27 g / g or more, (2) 0.90 wt The absorption capacity under pressure at 1.9 kPa with respect to a 10% sodium chloride aqueous solution is 20 g / g or more, and (3) the absorption capacity under pressure at 4.8 kPa with respect to a 0.90% by weight sodium chloride aqueous solution is 10 g / g or more. (4) Absorption rate with respect to 0.90% by weight sodium chloride aqueous solution is 20 seconds or more and 50 seconds or less, and (5) JIS standard sieve having an opening of 150 μm with respect to 100 parts by weight of the water-absorbent resin granulated product. Zero particles passing through It is characterized in that part or 5 or less parts by weight.
上記の構成によれば、吸水性樹脂造粒物をおむつ等の製品に使用した場合に、製品に漏れや戻り量がほとんど生じない。そのため、高物性な製品を得ることができる。 According to said structure, when a water absorbent resin granulated material is used for products, such as a diaper, a leak and return amount hardly arise in a product. Therefore, a product with high physical properties can be obtained.
(実施の形態1)
〔吸水性樹脂粉末〕
先ず、本発明に使用される吸水性樹脂粉末の製造方法について述べる。なお、本発明に係る吸水性樹脂造粒物とは、換言すると粒子状吸水剤である。また、本発明に係る吸水性樹脂粒子とは、換言すると吸水性樹脂粉末である。本明細書においては、上記の文言を適宜使用する。粒子状吸水剤の製造に際して使用される吸水性樹脂粉末は、公知の吸水性樹脂が広く使用され、その中でも、カルボキシル基を有するものが好ましく使用され、典型的にはアクリル酸及び/又はその塩を主成分とする親水性不飽和単量体を重合、架橋することにより得られ、水中において50倍から3000倍という多量の水を吸収し、ヒドロゲルを形成する従来公知の吸水性樹脂樹脂の粉末(略称;アクリル酸塩系吸水性樹脂)である。また、上記吸水性樹脂としては、該吸水性樹脂中の水可溶成分(米国再発行特許Re32649号の平行抽出性重合体で規定)が40重量%以下(下限0重量%)、好ましくは30重量%以下、より好ましくは20重量%以下、さらに好ましくは15重量%以下のものが用いられる。なお、本願発明で粉末とは含水率(実施例で規定)が0〜30重量%、好ましくは0〜20重量%、特に0〜10重量%の粉体をさす。
(Embodiment 1)
[Water absorbent resin powder]
First, a method for producing a water absorbent resin powder used in the present invention will be described. In addition, the water absorbent resin granulated product according to the present invention is, in other words, a particulate water absorbing agent. The water absorbent resin particles according to the present invention are water absorbent resin powders in other words. In the present specification, the above terms are used as appropriate. As the water-absorbing resin powder used in the production of the particulate water-absorbing agent, known water-absorbing resins are widely used. Among them, those having a carboxyl group are preferably used, and typically acrylic acid and / or a salt thereof. Conventionally known water-absorbing resin resin powder that is obtained by polymerizing and crosslinking a hydrophilic unsaturated monomer containing as a main component, absorbing a large amount of water from 50 to 3000 times in water to form a hydrogel (Abbreviation: acrylate-based water-absorbing resin). In addition, the water-absorbent resin contains 40% by weight or less (lower limit of 0% by weight), preferably 30% of a water-soluble component in the water-absorbent resin (specified by the parallel extractable polymer of US Reissue Patent Re32649). A weight percent or less, more preferably 20 weight percent or less, and even more preferably 15 weight percent or less is used. In the present invention, the powder means a powder having a water content (specified in the examples) of 0 to 30% by weight, preferably 0 to 20% by weight, particularly 0 to 10% by weight.
上記アクリル酸塩としては、アクリル酸のアルカリ金属塩、アンモニウム塩及びアミン塩等を例示することができる。上記吸水性樹脂は、その構成単位としてアクリル酸10〜40モル%、アクリル酸塩60〜90モル%(但し、両者の合計量は100モル%とする)の範囲にあるものが好ましい。アクリル酸ないしその重合体の中和は、不飽和単量体で行ってもよいし、重合途中あるいは重合後に行ってもよい。 Examples of the acrylate include alkali metal salts, ammonium salts and amine salts of acrylic acid. The water-absorbing resin preferably has 10 to 40 mol% acrylic acid and 60 to 90 mol% acrylate as the constituent units (however, the total amount of both is 100 mol%). Neutralization of acrylic acid or its polymer may be performed with an unsaturated monomer, or may be performed during or after polymerization.
吸水性樹脂を得るに際しては、必要に応じて、これらアクリル酸又はその塩に併用して、アクリル酸以外の不飽和単量体を含有していてもよい。アクリル酸以外の不飽和単量体としては、特に限定されるものではないが、具体的には、例えば、メタクリル酸、マレイン酸、2−(メタ)アクリルアミド−2−メチルプロパンスルホン酸、2−(メタ)アクリロイルエタンスルホン酸などのアニオン性不飽和単量体及びその塩;(メタ)アクリルアミド、2−ヒドロキシプロピル(メタ)アクリレート、(メトキシ)ポリエチレングリコール(メタ)アクリレートなどのノニオン性の親水基含有不飽和単量体;N,N−ジメチルアミノエチル(メタ)アクリレートなど四級塩等のカチオン性不飽和単量体等が挙げられる。これら不飽和単量体は、単独で用いてもよく、適宜2種以上を混合してもよい。これら該アクリル酸以外の不飽和単量体は、主成分として用いるアクリル酸及びその塩との合計量に対して、通常0〜30モル%以下、好ましくは0〜10モル%以下で用いられる。 When obtaining a water-absorbent resin, it may contain unsaturated monomers other than acrylic acid in combination with these acrylic acids or salts thereof, if necessary. The unsaturated monomer other than acrylic acid is not particularly limited. Specifically, for example, methacrylic acid, maleic acid, 2- (meth) acrylamide-2-methylpropanesulfonic acid, 2- Anionic unsaturated monomers such as (meth) acryloylethanesulfonic acid and salts thereof; nonionic hydrophilic groups such as (meth) acrylamide, 2-hydroxypropyl (meth) acrylate and (methoxy) polyethylene glycol (meth) acrylate Containing unsaturated monomer; Cationic unsaturated monomer such as quaternary salt such as N, N-dimethylaminoethyl (meth) acrylate. These unsaturated monomers may be used independently and may mix 2 or more types suitably. These unsaturated monomers other than acrylic acid are usually used in an amount of 0 to 30 mol%, preferably 0 to 10 mol%, based on the total amount of acrylic acid and its salt used as the main component.
また、本発明に用いられる吸水性樹脂を得るために上述のアクリル酸又はその塩を主成分とする親水性不飽和単量体を重合するに際し、バルク重合や沈殿重合を行うことが可能であるが、性能面や重合の制御の容易さから、上記親水性不飽和単量体を水溶液とすることによる水溶液重合又は逆相懸濁重合を行うことが好ましい。 In order to obtain the water-absorbent resin used in the present invention, it is possible to carry out bulk polymerization or precipitation polymerization when polymerizing the hydrophilic unsaturated monomer mainly composed of the above-mentioned acrylic acid or a salt thereof. However, from the viewpoint of performance and ease of polymerization control, it is preferable to perform aqueous solution polymerization or reverse phase suspension polymerization by using the hydrophilic unsaturated monomer as an aqueous solution.
なお、逆相懸濁重合とは、単量体水溶液を疎水性有機溶媒に懸濁させる重合法であり、例えば、米国特許4093776号、同4367323号、同4446261号、同4683274号、同5244735号などの米国特許に記載されている。水溶液重合は分散溶媒を用いずに単量体水溶液を重合する方法であり、例えば、米国特許4625001号、同4873299号、同4286082号、同4973632号、同4985518号、同5124416号、同5250640号、同5264495号、同5145906号、同5380808号などの米国特許や、欧州特許0811636号、同0955086号,同0922717号などの欧州特許に記載されている。これら重合法に例示の不飽和単量体、架橋剤、開始剤なども本発明では適用できる。 The reverse phase suspension polymerization is a polymerization method in which an aqueous monomer solution is suspended in a hydrophobic organic solvent. For example, U.S. Pat. Nos. 4,093,764, 4,367,323, 4,446,261, 4,683,274, and 5,244,735. Are described in US patents. Aqueous solution polymerization is a method of polymerizing an aqueous monomer solution without using a dispersion solvent. For example, US Pat. Nos. 4,462,001, 4,873,299, 4,286,082, 4,973,632, 4,985,518, 5,124,416, 5,250,640 are used. No. 5,264,495, US Pat. No. 5,145,906 and US Pat. No. 5,380,808, and European patents such as European Patents 081636, 09555086, and 0922717. The unsaturated monomers, crosslinking agents, initiators and the like exemplified in these polymerization methods can also be applied in the present invention.
尚、上記親水性不飽和単量体を水溶液とする場合の該水溶液の(以下、単量体水溶液と称する)中の不飽和単量体の濃度は、特に限定されるものではないが、好ましくは10〜70重量%、より好ましくは20〜40重量%である。また、上記水溶液重合または逆相懸濁重合を行う際には、水以外の溶媒を必要に応じて併用してもよく、併用して用いられ溶媒の種類は、特に限定されるものではない。 The concentration of the unsaturated monomer in the aqueous solution (hereinafter referred to as the monomer aqueous solution) when the hydrophilic unsaturated monomer is an aqueous solution is not particularly limited, but is preferably Is 10 to 70% by weight, more preferably 20 to 40% by weight. Moreover, when performing the said aqueous solution polymerization or reverse phase suspension polymerization, you may use together solvents other than water as needed, and the kind of solvent used together is not specifically limited.
上記の重合を開始させる際には、例えば、過硫酸カリウム、過硫酸アンモニウム、過硫酸ナトリウム、t−ブチルハイドロパーオキサイド、過酸化水素、2,2’−アゾビス(2−アミノジプロパン)二塩酸塩等のラジカル重合開始剤を用いることができる。さらに、これら重合開始剤の分解を促進する還元剤を併用し、両者を組み合わせることによりレドックス系開始剤とすることもできる。上記の還元剤としては、例えば、亜硫酸ナトリウム、亜硫酸水素ナトリウム等の(重)亜硫酸(塩)、L−アスコルビン酸(塩)、第一鉄塩等の還元性金属(塩)、アミン類等が挙げられるが、特に限定されるものではない。これら重合開始剤の使用量は物性面から不飽和単量体に対して、通常0.001〜2モル%、好ましくは0.01〜0.05モル%である。 When starting the above polymerization, for example, potassium persulfate, ammonium persulfate, sodium persulfate, t-butyl hydroperoxide, hydrogen peroxide, 2,2′-azobis (2-aminodipropane) dihydrochloride A radical polymerization initiator such as can be used. Further, a reducing agent that promotes the decomposition of the polymerization initiator can be used in combination, and a redox initiator can be obtained by combining the two. Examples of the reducing agent include (bi) sulfurous acid (salt) such as sodium sulfite and sodium bisulfite, L-ascorbic acid (salt), reducing metal (salt) such as ferrous salt, amines, and the like. Although it is mentioned, it is not particularly limited. The amount of these polymerization initiators used is usually from 0.001 to 2 mol%, preferably from 0.01 to 0.05 mol%, based on the physical properties, based on the unsaturated monomer.
また、反応系に放射線、電子線、紫外線などの活性エネルギー線を照射することにより重合反応を行ってもよい。尚、上記重合反応における反応温度は、特に限定されるものでないが、通常10〜130℃、好ましくは20〜120℃の範囲内が好ましい。また、反応時間も特に限定されるものではなく、親水性不飽和単量体や重合開始剤の種類、反応温度などに応じて適宜決定すればよい。 Further, the polymerization reaction may be carried out by irradiating the reaction system with active energy rays such as radiation, electron beam and ultraviolet ray. The reaction temperature in the polymerization reaction is not particularly limited, but is usually 10 to 130 ° C, preferably 20 to 120 ° C. Further, the reaction time is not particularly limited, and may be appropriately determined according to the kind of the hydrophilic unsaturated monomer or the polymerization initiator, the reaction temperature, and the like.
本発明に用いられる吸水性樹脂は、架橋剤を使用しない自己架橋型のものであってもよいが、一分子内に、2個以上の重合性不飽和基や、2個以上の反応性基を有する内部架橋剤を共重合又は反応させたものが好ましい。これら内部架橋剤の具体例としては、例えば、N,N’−メチレンビス(メタ)アクリルアミド、(ポリ)エチレングリコール(メタ)アクリレート、(ポリ)プロピレングリコールジ(メタ)アクリレート、トリメチルロールプロパントリ(メタ)アクリレート、グリセリントリ(メタ)アクリレート、グリセリンアクリレートメタクリレート、エチレンオキサイド変性トリメチロールプロパントリ(メタ)アクリレート、ペンタエリスリトールヘキサ(メタ)アクリレート、トリアリルシアヌレート、トリアリルイソシアヌレート、トリアリルホスフェート、トリアリルアミン、ポリ(メタ)アリロキシアルカン、(ポリ)エチレングリコールジグリシジルエーテル、グリセロールジグリシジルエーテル、エチレングリコール、ポリエチレングリコール、プロピレングリコール、グリセリン、ペンタエリスリトール、エチレンジアミン、エチレンカーボネート、プロピレンカーボネート、ポリエチレンイミン、グリシジル(メタ)アクリレート等を挙げることができる。 The water-absorbing resin used in the present invention may be of a self-crosslinking type that does not use a crosslinking agent, but in one molecule, two or more polymerizable unsaturated groups or two or more reactive groups. Those obtained by copolymerizing or reacting an internal crosslinking agent having Specific examples of these internal crosslinking agents include, for example, N, N′-methylenebis (meth) acrylamide, (poly) ethylene glycol (meth) acrylate, (poly) propylene glycol di (meth) acrylate, trimethylolpropane tri (meta) ) Acrylate, glycerin tri (meth) acrylate, glycerin acrylate methacrylate, ethylene oxide modified trimethylolpropane tri (meth) acrylate, pentaerythritol hexa (meth) acrylate, triallyl cyanurate, triallyl isocyanurate, triallyl phosphate, triallylamine , Poly (meth) allyloxyalkane, (poly) ethylene glycol diglycidyl ether, glycerol diglycidyl ether, ethylene glycol, polyethylene Glycol, propylene glycol, glycerol, pentaerythritol, ethylenediamine, ethylene carbonate, propylene carbonate, polyethylenimine, and glycidyl (meth) acrylate.
また、これら内部架橋剤は単独で用いてもよく、適宜2種以上を混合して用いてもよい。また、これら内部架橋剤は反応系に一括添加してもよく、分割添加してもよい。得られる吸水性樹脂の吸収特性等を考慮して、2個以上の重合性不飽和基を有する化合物を必須に用いることが好ましく、その使用量としては、前記の不飽和単量体成分に対して好ましくは0.005〜2モル%、より好ましくは0.01〜1モル%である。 Moreover, these internal crosslinking agents may be used independently and may mix and use 2 or more types suitably. These internal cross-linking agents may be added all at once to the reaction system, or may be added in divided portions. In consideration of the absorption characteristics of the resulting water-absorbent resin, it is preferable to use a compound having two or more polymerizable unsaturated groups, and the amount used is relative to the unsaturated monomer component. It is preferably 0.005 to 2 mol%, more preferably 0.01 to 1 mol%.
なお、重合に際しては、反応系に、炭酸(水素)塩、二酸化炭素、アゾ化合物、不活性有機溶媒などの各種発泡剤;澱粉・セルロース、澱粉・セルロースの誘導体、ポリビニルアルコール、ポリアクリル酸(塩)、ポリアクリル酸(塩)架橋体等の親水性高分子;各種界面活性剤;次亜燐酸(塩)等の連鎖移動剤、キレート材などを単量体に0〜30重量%、好ましくは0〜10重量%で添加してもよい。 In the polymerization, various foaming agents such as carbonate (hydrogen) salt, carbon dioxide, azo compound, inert organic solvent; starch / cellulose, starch / cellulose derivatives, polyvinyl alcohol, polyacrylic acid (salt) ), Hydrophilic polymers such as crosslinked polyacrylic acid (salt), various surfactants, chain transfer agents such as hypophosphorous acid (salt), chelating agents, etc., in the amount of 0 to 30% by weight, preferably You may add at 0 to 10 weight%.
上記重合反応により得られた重合体がゲル状である場合には、該ゲル状重合体は、乾燥し、乾燥の前および/または後で通常粉砕されて吸水性樹脂粉末とする。 When the polymer obtained by the polymerization reaction is in a gel form, the gel polymer is dried, and is usually pulverized before and / or after drying to obtain a water absorbent resin powder.
また、該ゲル状重合体の乾燥方法は特に限定されず、通常の乾燥機又は加熱炉が広く用いられ、乾燥は通常80〜250℃、好ましくは100〜220℃、より好ましくは120〜200℃の温度範囲で行われる。乾燥時間は、該ゲル状重合体の表面積、含水率、および乾燥機又は加熱炉の種類に依存し、目的とする含水率になるように選択される。 Moreover, the drying method of this gel-like polymer is not specifically limited, A normal dryer or a heating furnace is widely used, and drying is usually 80-250 degreeC, Preferably it is 100-220 degreeC, More preferably, it is 120-200 degreeC. In the temperature range. The drying time depends on the surface area of the gel polymer, the moisture content, and the type of the dryer or heating furnace, and is selected so as to achieve the desired moisture content.
本発明に用いられる吸水性樹脂粉末としては、粉砕により得られた粒度のものをそのまま用いてもよいし、目的に応じて意図的に粒度を調整したものを用いてもよい。また、吸水性樹脂粉末の形状としては、造粒強度の面から、逆相懸濁重合で得られた球形よりも、水溶液重合で得られた不定形のものが好ましい。また本発明の造粒に用いられる吸水性樹脂粉末は、表面架橋処理が施されていてもよいし、施されていなくてもよいが、好ましくは表面架橋処理が施されている吸水性樹脂粉末である。かかる表面架橋処理前または表面架橋処理後の吸水性樹脂粉末の重量平均粒子径は通常50〜1000μmであり、後述する二種類の吸水性樹脂粉末(第一、第二)の粒度分布に応じて調整すればよい。 As the water-absorbent resin powder used in the present invention, those having a particle size obtained by pulverization may be used as they are, or those having an intentionally adjusted particle size according to the purpose may be used. The shape of the water-absorbent resin powder is preferably an indeterminate shape obtained by aqueous solution polymerization rather than a spherical shape obtained by reverse phase suspension polymerization in terms of granulation strength. The water-absorbing resin powder used for granulation of the present invention may or may not be subjected to surface cross-linking treatment, but preferably water-absorbing resin powder subjected to surface cross-linking treatment. It is. The weight average particle diameter of the water-absorbent resin powder before or after the surface cross-linking treatment is usually 50 to 1000 μm, depending on the particle size distribution of two types of water-absorbing resin powders (first and second) described later. Adjust it.
(2)表面架橋処理
以下、表面架橋処理についてさらに説明する。本発明に用いられる表面架橋処理としては、当業界において該用途に用いられている公知の表面架橋処理(例えば、前記の特許文献1〜8)が好適に用いられる。
(2) Surface cross-linking treatment Hereinafter, the surface cross-linking treatment will be further described. As the surface cross-linking treatment used in the present invention, a known surface cross-linking treatment (for example, Patent Documents 1 to 8 described above) used for this purpose in the art is suitably used.
例えば、用いられる表面架橋剤としては、エチレングリコール、ジエチレングリコール、プロピレングリコール、トリエチレングリコール、テトラエチレングリコール、ポリエチレングリコール、1,3−プロパンジオール、ジプロピレングリコール、2,2,4−トリメチル−1,3−ペンタンジオール、ポリプロピレングリコール、グリセリン、ポリグリセリン、2−ブテン−1,4−ジオール、1,4−ブタンジオール、1,5−ペンタンジオール、1,6−ヘキサンジオール、1,2−シクロヘキサンジメタノール1,2−シクロヘキサノール、トリメチロールプロパン、ジエタノールアミン、トリエタノールアミン、ポリオキシプロピレン、オキシエチレン−オキシプロピレンブロック共重合体、ペンタエリスリトール、ソルビトール等の多価アルコール化合物;(ポリ)エチレングリコールジグリシジルエーテル、(ポリないしジないしモノ)グリセロールポリグリシジルエーテル、(ポリ)プロピレングリコールジグリシジルエーテル、グリシドール等のエポキシ化合物;エチレンジアミン、ジエチレントリアミン、トリエチレンテトラミン、テトラエチレンペンタミン、ペンタエチレンヘキサミン、ポリエチレンイミン等の多価アミン化合物やそれらの無機塩ないし有機塩(アジリジニウム塩など);2,4−トリレンジイソシアネートなどの多価イソシアネート化合物;1,2−エチレンビスオキサゾリン等の多価オキサゾリン化合物;1,3−ジオキソラン−2−オンなどのカーボネート化合物;エピクロロヒドリン、エピブロムヒドリン、α−メチルエピクロロヒドリン等のハロエポキシ化合物;亜鉛、カルシウム、マグネシウム、アルミニウム、鉄、ジルコニウム等の水酸化物又は塩化物等の多価金属化合物等が挙げられる。これら表面架橋剤は、単独で用いてもよく、また、反応性を考慮して2種類以上を混合して用いてもよい。これらの表面架橋剤の中でも、多価アルコール化合物、エポキシ化合物、多価アミン化合物やそれらの塩、アルキレンカーボネート化合物からなる群より選ばれる少なくとも1種の化合物、さらには多価アルコール化合物が好適である。 For example, as the surface crosslinking agent used, ethylene glycol, diethylene glycol, propylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, 1,3-propanediol, dipropylene glycol, 2,2,4-trimethyl-1, 3-pentanediol, polypropylene glycol, glycerin, polyglycerin, 2-butene-1,4-diol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,2-cyclohexanedi Methanol 1,2-cyclohexanol, trimethylolpropane, diethanolamine, triethanolamine, polyoxypropylene, oxyethylene-oxypropylene block copolymer, pentaerythritol, sorbite Polyhydric alcohol compounds such as ruthenium; Epoxy compounds such as (poly) ethylene glycol diglycidyl ether, (poly or di to mono) glycerol polyglycidyl ether, (poly) propylene glycol diglycidyl ether, glycidol; ethylenediamine, diethylenetriamine, triethylene Polyamines such as tetramine, tetraethylenepentamine, pentaethylenehexamine, and polyethyleneimine, and their inorganic or organic salts (eg, aziridinium salts); polyvalent isocyanate compounds such as 2,4-tolylene diisocyanate; -Polyvalent oxazoline compounds such as ethylene bisoxazoline; carbonate compounds such as 1,3-dioxolan-2-one; epichlorohydrin, epibromohydrin, α-methyl epichloro Examples include haloepoxy compounds such as rhohydrin; hydroxides such as zinc, calcium, magnesium, aluminum, iron and zirconium, or polyvalent metal compounds such as chloride. These surface crosslinking agents may be used alone or in combination of two or more in consideration of reactivity. Among these surface crosslinking agents, polyhydric alcohol compounds, epoxy compounds, polyhydric amine compounds and salts thereof, at least one compound selected from the group consisting of alkylene carbonate compounds, and polyhydric alcohol compounds are preferred. .
上記表面架橋処理において、米国特許第5422405号公報にて提案されているように、カルボキシル基と反応し得る表面架橋剤が溶解度パラメータ(SP値)の互いに異なる第一表面架橋剤及び第二表面架橋剤を組み合わせてなる場合には、加圧下吸収倍率がさらに一層優れた吸収剤を得ることができる。上記の第一表面架橋剤は、カルボキシル基と反応可能な、溶解度パラメータが12.5(cal/cm3)1/2以上の化合物が好ましく、13.0(cal/cm3)1/2以上の化合物がより好ましい。上記の第二表面架橋剤は、カルボキシル基と反応可能な、溶解度パラメータが12.5(cal/cm3)1/2未満の化合物が好ましく、9.5(cal/cm3)1/2〜12.0(cal/cm3)1/2の範囲内の化合物がより好ましい。 In the surface cross-linking treatment, as proposed in US Pat. No. 5,422,405, the first surface cross-linking agent and the second surface cross-linking agent having different solubility parameters (SP values) as surface cross-linking agents capable of reacting with carboxyl groups. In the case of combining agents, an absorbent having an even better absorption capacity under pressure can be obtained. The first surface crosslinking agent is preferably a compound capable of reacting with a carboxyl group and having a solubility parameter of 12.5 (cal / cm 3 ) 1/2 or more, and 13.0 (cal / cm 3 ) 1/2 or more. The compound of is more preferable. The second surface crosslinking agent is preferably a compound capable of reacting with a carboxyl group and having a solubility parameter of less than 12.5 (cal / cm 3 ) 1/2 , and 9.5 (cal / cm 3 ) 1/2 to A compound within the range of 12.0 (cal / cm 3 ) 1/2 is more preferred.
表面架橋剤の使用量は、用いる化合物やそれらの組み合わせ等にもよるが、吸水性樹脂粉末の固形分100重量部に対して、0.001重量部〜10重量部が好ましく、0.01重量部〜5重量部がより好ましい。 The amount of the surface cross-linking agent used is preferably 0.001 to 10 parts by weight, preferably 0.01 parts by weight with respect to 100 parts by weight of the solid content of the water-absorbent resin powder, although it depends on the compounds used and combinations thereof. Part to 5 parts by weight is more preferred.
本発明において、吸水性樹脂粉末と表面架橋剤とを混合する際には、表面架橋剤の溶媒として水を用いることが好ましい。水の使用量は吸水性樹脂粉末の100重量部に対して、好ましくは0を越え20重量部以下、より好ましくは0.5重量部〜10重量部の範囲内である。 In the present invention, when mixing the water absorbent resin powder and the surface cross-linking agent, it is preferable to use water as a solvent for the surface cross-linking agent. The amount of water used is preferably more than 0 and 20 parts by weight or less, more preferably 0.5 to 10 parts by weight, based on 100 parts by weight of the water-absorbent resin powder.
吸水性樹脂粉末と表面架橋剤とを混合する際には、必要に応じて、親水性有機溶媒(水性液体)を併用してもよい。上記の親水性有機溶媒としては、例えば、メチルアルコール、エチルアルコール、n−プロピルアルコール、イソプロピルアルコールなどの一価アルコール類;アセトン等のケトン類;ジオキサン、テトラヒドロフラン等のエーテル類;等が挙げられる。親水性有機溶媒の使用量は吸水性樹脂粉末の100重量部に対して、好ましくは20重量部以下、より好ましくは0〜10重量部である。 When mixing the water-absorbent resin powder and the surface cross-linking agent, a hydrophilic organic solvent (aqueous liquid) may be used in combination as necessary. Examples of the hydrophilic organic solvent include monohydric alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, and isopropyl alcohol; ketones such as acetone; ethers such as dioxane and tetrahydrofuran; The amount of the hydrophilic organic solvent to be used is preferably 20 parts by weight or less, more preferably 0 to 10 parts by weight with respect to 100 parts by weight of the water absorbent resin powder.
さらに、混合性向上や反応生向上のため、界面活性剤、不活性無機粉末、有機酸(塩)、無機酸(塩)、苛性ソーダなど塩基性化合物を吸水性樹脂100重量部に0〜5重量部で併用してもよい。 Furthermore, in order to improve the mixing property and the reaction life, 0 to 5 weights of a basic compound such as a surfactant, an inert inorganic powder, an organic acid (salt), an inorganic acid (salt), and caustic soda in 100 parts by weight of the water-absorbing resin. You may use together.
上記吸水性樹脂粉末と表面架橋剤とを混合した後、さらに、加熱処理を行い、吸水性樹脂粉末の表面近傍を架橋させる。すなわち、吸水性樹脂粉末の表面近傍で架橋剤を反応させるには、架橋剤の反応性、製造装置の簡易性、生産性を考慮すると加熱処理を行うのが好ましい。加熱処理の処理温度は用いる表面架橋剤にもよるが、80〜250℃、さらには100〜200℃の範囲(熱媒温度)が好ましい。上記の加熱処理は通常の乾燥機又は加熱炉を用いて行うことができる。乾燥機としては、例えば、溝型混合乾燥機、ロータリー乾燥機、ディスク乾燥機、流動層乾燥機、気流型乾燥機、及び赤外線乾燥機等が挙げられる。 After mixing the water absorbent resin powder and the surface cross-linking agent, heat treatment is further performed to crosslink the vicinity of the surface of the water absorbent resin powder. That is, in order to react the cross-linking agent in the vicinity of the surface of the water-absorbent resin powder, it is preferable to perform heat treatment in consideration of the reactivity of the cross-linking agent, the simplicity of the production apparatus, and the productivity. Although the processing temperature of heat processing is based also on the surface crosslinking agent to be used, the range (heating medium temperature) of 80-250 degreeC and also 100-200 degreeC is preferable. Said heat processing can be performed using a normal dryer or a heating furnace. Examples of the dryer include a groove-type mixing dryer, a rotary dryer, a disk dryer, a fluidized bed dryer, an airflow dryer, and an infrared dryer.
(3)水性液の添加
本発明の粒子状吸水剤の製造方法は、第一の吸水性樹脂粉末および水性液を混合する工程(a)、該水性液を含む第一の吸水性樹脂粉末および第二の吸水性樹脂粉末を混合する工程(b)、を含むことを特徴とする粒子状吸水剤の製造方法である。
(3) Addition of aqueous liquid The method for producing the particulate water-absorbing agent of the present invention comprises the step (a) of mixing the first water-absorbent resin powder and the aqueous liquid, the first water-absorbent resin powder containing the aqueous liquid, and A step (b) of mixing a second water-absorbent resin powder, and a method for producing a particulate water-absorbing agent.
本発明に用いられる第一の吸水性樹脂粉末と第二の吸水性樹脂粉末は、同じ成分の吸水性樹脂粉末であってもよく、異なる成分の吸水性樹脂粉末であってもよい。また本発明に用いられる二種類の吸水性樹脂粉末(第一、第二)は同じ粒度分布であってもよく、異なる粒度分布であってもよいが、好ましくは、第一、第二がポリアクリル酸塩系吸水性樹脂であって、第一の吸水性樹脂粉末の重量平均粒子径が第二の吸水性樹脂粉末の重量平均粒子径よりも小さい組み合わせを用いる。さらに、二種類の吸水性樹脂粉末(第一、第二)以外にその他、第三ないしそれ以上の吸水性樹脂粉末があってもよい。また、水性液の混合性から、第一の吸水性樹脂粉末は表面架橋され、さらに好ましくは第二の吸水性樹脂粉末も表面架橋されている。 The first water-absorbing resin powder and the second water-absorbing resin powder used in the present invention may be water-absorbing resin powders having the same component or water-absorbing resin powders having different components. Further, the two types of water-absorbent resin powders (first and second) used in the present invention may have the same particle size distribution or different particle size distributions. A combination of acrylate-based water-absorbent resins, in which the weight-average particle diameter of the first water-absorbent resin powder is smaller than the weight-average particle diameter of the second water-absorbent resin powder is used. In addition to the two types of water-absorbing resin powders (first and second), there may be a third or more water-absorbing resin powder. In addition, the first water-absorbent resin powder is surface-crosslinked, and more preferably the second water-absorbent resin powder is also surface-crosslinked, due to the miscibility of the aqueous liquid.
第一の吸水性樹脂粉末の重量平均粒子径は200μm未満であることが好ましい。また、第一の吸水性樹脂粉末は粒子径が150μm以下の吸水性樹脂粉末の割合が好ましくは30重量%以上(上限100重量%)、より好ましくは50重量%以上、さらに好ましくは70重量%以上、さらにより好ましくは90重量%以上である。 The first water-absorbent resin powder preferably has a weight average particle diameter of less than 200 μm. Further, the proportion of the water-absorbent resin powder having a particle diameter of 150 μm or less in the first water-absorbent resin powder is preferably 30% by weight or more (upper limit 100% by weight), more preferably 50% by weight or more, and further preferably 70% by weight. As mentioned above, it is still more preferably 90% by weight or more.
第二の吸水性樹脂粉末の重量平均粒子径は好ましくは200〜800μm、より好ましくは230〜600μm、さらに好ましくは260〜500μmである。 The weight average particle diameter of the second water absorbent resin powder is preferably 200 to 800 μm, more preferably 230 to 600 μm, and still more preferably 260 to 500 μm.
第二の吸水性樹脂粉末は乾燥した状態であることが好ましい。本発明において乾燥した状態とは吸水性樹脂粉末の含水率が必ずしも0重量%である必要はなく、通常、0〜15重量%、好ましくは0〜10重量%の範囲内であればいい。 The second water absorbent resin powder is preferably in a dry state. In the present invention, the dry state does not necessarily mean that the water content of the water-absorbent resin powder is 0% by weight, and is usually within the range of 0 to 15% by weight, preferably 0 to 10% by weight.
第一の吸水性樹脂粉末と第二の吸水性樹脂粉末の割合は特に限定はないが、通常は第一の吸水性樹脂粉末と第二の吸水性樹脂粉末の割合である第一の吸水性樹脂粉末/第二の吸水性樹脂粉末の重量比が1/99〜50/50、好ましくは2/98〜40/60、より好ましくは3/97〜30/70の範囲内である。 The ratio of the first water-absorbent resin powder and the second water-absorbent resin powder is not particularly limited, but is usually the ratio of the first water-absorbent resin powder and the second water-absorbent resin powder. The weight ratio of resin powder / second water-absorbent resin powder is in the range of 1/99 to 50/50, preferably 2/98 to 40/60, more preferably 3/97 to 30/70.
第一の吸水性樹脂粉末と第二の吸水性樹脂粉末の製造方法は前述の製造方法であれば制限はなく、それぞれ単独で重合、乾燥、粉砕、必要に応じて粒度調製を行い、さらに必要により表面架橋処理を施して製造してもよいし、重合、乾燥、粉砕、必要により粒度調整を行い、さらに必要により表面架橋処理を施して得られた吸水性樹脂粉末を分級により第一の吸水性樹脂粉末と第二の吸水性樹脂粉末に分けて製造しても構わない。水性液の混合性から、好ましくは、表面架橋処理された吸水性樹脂粉末が第一の吸水性樹脂粉末、さらには第二の吸水性樹脂粉末でも使用される。 The production method of the first water-absorbent resin powder and the second water-absorbent resin powder is not limited as long as it is the above-mentioned production method, and each of them is individually polymerized, dried, pulverized, and the particle size is adjusted as necessary. May be produced by subjecting to a surface cross-linking treatment, polymerization, drying, pulverization, particle size adjustment as necessary, and water-absorbing resin powder obtained by subjecting the surface cross-linking treatment to a first water absorption by classification. You may divide and manufacture in the resin resin powder and the 2nd water absorbing resin powder. In view of the miscibility of the aqueous liquid, preferably, the water-absorbing resin powder subjected to surface crosslinking treatment is used as the first water-absorbing resin powder, and further the second water-absorbing resin powder.
本発明の目的を達成する為には、二種類の吸水性樹脂粉末の温度は特に限定されないが、通常5℃以上、好ましくは20℃以上であり、100℃を越えても大きな変化がないため、通常、100℃以下で行われる。 In order to achieve the object of the present invention, the temperature of the two types of water-absorbent resin powder is not particularly limited, but is usually 5 ° C. or higher, preferably 20 ° C. or higher, and there is no significant change even when it exceeds 100 ° C. Usually, it is performed at 100 ° C. or lower.
本発明において、第一の吸水性樹脂粉末と混合する水性液としては、特に限定されないが、例えば、水や、水溶性塩類あるいは親水性有機溶剤を含んだ水性液などが挙げられる。物性や造粒強度の面から、水性液中の水の割合は90〜100重量%、好ましくは95〜100重量%、より好ましくは99〜100重量%の範囲内であり、少量の架橋剤(例えば、前記表面架橋剤)や界面活性剤を含んでいてもよい。水性液に架橋剤を併用することで、水可溶成分の低減や、造粒強度のさらなる向上を図ることができる場合もある。 In the present invention, the aqueous liquid to be mixed with the first water-absorbent resin powder is not particularly limited, and examples thereof include water, an aqueous liquid containing a water-soluble salt, or a hydrophilic organic solvent. From the viewpoint of physical properties and granulation strength, the proportion of water in the aqueous liquid is in the range of 90 to 100% by weight, preferably 95 to 100% by weight, more preferably 99 to 100% by weight. For example, the surface cross-linking agent) or a surfactant may be included. By using a crosslinking agent in combination with the aqueous liquid, it may be possible to reduce the water-soluble component and further improve the granulation strength.
本発明の目的を達成する為には、水性液の温度は特に限定されないが、通常5℃以上で沸点以下、好ましくは20℃以上であり、100℃を越えても大きな変化がないため、通常、100℃以下で行われる。 In order to achieve the object of the present invention, the temperature of the aqueous liquid is not particularly limited, but is usually 5 ° C. or higher and the boiling point or lower, preferably 20 ° C. or higher, and since it does not change greatly even when it exceeds 100 ° C., At 100 ° C. or lower.
水性液の使用量は、第一の吸水性樹脂粉末と第二の吸水性樹脂粉末を合計した重量100重量部に対し、通常1〜50重量部、好ましくは5〜30重量部、より好ましくは10〜20重量部である。水性液の使用量が50重量部を越えると、造粒物として扱うことが困難となる上、乾燥コスト等の面で不利である。一方、水性液の使用量が1重量部よりも少ない場合、造粒強度が不十分になり、最終製品において造粒の特性を発揮することができなくなるおそれがある。また、混合が不均一になり造粒物が得られないことがある。 The amount of the aqueous liquid used is usually 1 to 50 parts by weight, preferably 5 to 30 parts by weight, more preferably 100 parts by weight of the total weight of the first water absorbent resin powder and the second water absorbent resin powder. 10 to 20 parts by weight. When the amount of the aqueous liquid used exceeds 50 parts by weight, it is difficult to handle as a granulated product, and it is disadvantageous in terms of drying cost. On the other hand, when the amount of the aqueous liquid used is less than 1 part by weight, the granulation strength becomes insufficient, and there is a possibility that the granulation characteristics cannot be exhibited in the final product. Moreover, mixing may become non-uniform | heterogenous and a granulated material may not be obtained.
本発明にかかる該水性液を含む第一の吸水性樹脂粉末は、好ましくは含水ゲル状物である。すなわち、該含水ゲル状物の含水率(実施例で規定)は、通常20重量%以上、好ましくは30〜95重量%、より好ましくは40〜90重量%にまで水和されることで、より強固な造粒物が得られる。 The first water-absorbing resin powder containing the aqueous liquid according to the present invention is preferably a water-containing gel. That is, the water content (specified in the examples) of the water-containing gel is usually 20% by weight or more, preferably 30 to 95% by weight, more preferably 40 to 90% by weight. A strong granulated product is obtained.
本発明において、第一の吸水性樹脂粉末および水性液を混合する工程(a)は、特に制限はなく、第一の吸水性樹脂粉末および水性液を混合した後に巨大な凝集物がなく均一に混合できればよい。通常は第一の吸水性樹脂粉末に水性液を添加するが、水性液に対して第一の吸水性樹脂粉末を添加しても構わない。 In the present invention, the step (a) of mixing the first water-absorbent resin powder and the aqueous liquid is not particularly limited, and after mixing the first water-absorbent resin powder and the aqueous liquid, there is no huge aggregate and is uniform. It only needs to be mixed. Usually, an aqueous liquid is added to the first water absorbent resin powder, but the first water absorbent resin powder may be added to the aqueous liquid.
第一の吸水性樹脂粉末に水性液を混合する場合、その混合方法には特に制限はない。水性液を攪拌中の第一の吸水性樹脂粉末に一気に投入しても良いし、水性液を、例えば噴霧する等の方法で徐々に添加してもよい。しかし、水性液を第一の吸水性樹脂粉末に添加し始めてから、添加し終わるまでの時間が長い場合には、途中で第一の吸水性樹脂粉末が大きな凝集塊となったり、混練されたりして、吸水性樹脂の劣化を生じる。水性液の投入時間は好ましくは60秒以下、より好ましくは30秒以下、最も好ましくは10秒以下である。 When the aqueous liquid is mixed with the first water absorbent resin powder, the mixing method is not particularly limited. The aqueous liquid may be poured into the first water-absorbing resin powder being stirred at once, or the aqueous liquid may be gradually added by a method such as spraying. However, if it takes a long time from the start of addition of the aqueous liquid to the first water absorbent resin powder until the end of the addition, the first water absorbent resin powder becomes a large agglomerate or kneaded during the process. As a result, the water absorbent resin is deteriorated. The charging time of the aqueous liquid is preferably 60 seconds or less, more preferably 30 seconds or less, and most preferably 10 seconds or less.
上記とは逆に、水性液に第一の吸水性樹脂粉末を混合する場合、その混合方法には特に制限はない。例えば第一の吸水性樹脂粉末を、攪拌中の水性液に投入する方法でも本発明の目的を達成するための水性液を含んだ第一の吸水性樹脂粉末ができる。この場合は、吸水性樹脂粉末の投入時間は好ましくは60秒以下、より好ましくは30秒以下、最も好ましくは10秒以下である。また、第一の吸水性樹脂粉末と水性液とを同時に一気に投入して混合する方法でも、本発明の目的を達成するための水性液を含む第一の吸水性樹脂粉末ができる。この場合は、両原料の投入時間が、60秒以下であることが好ましく、30秒以下であることがさらに好ましく、10秒以下であることがもっとも好ましい。また、両原料が、連続的に同時に投入され、混合され、連続的に本発明の目的を達成するための水性液を含む第一の吸水性樹脂粉末が製造される場合もある。 Contrary to the above, when the first water-absorbing resin powder is mixed with the aqueous liquid, the mixing method is not particularly limited. For example, the first water-absorbing resin powder containing an aqueous liquid for achieving the object of the present invention can be obtained by a method in which the first water-absorbing resin powder is introduced into the aqueous liquid being stirred. In this case, the charging time of the water-absorbent resin powder is preferably 60 seconds or less, more preferably 30 seconds or less, and most preferably 10 seconds or less. In addition, the first water-absorbing resin powder containing the aqueous liquid for achieving the object of the present invention can also be obtained by a method in which the first water-absorbing resin powder and the aqueous liquid are simultaneously charged and mixed. In this case, the charging time of both raw materials is preferably 60 seconds or shorter, more preferably 30 seconds or shorter, and most preferably 10 seconds or shorter. Moreover, both raw materials may be continuously added and mixed simultaneously to produce a first water-absorbent resin powder containing an aqueous liquid for continuously achieving the object of the present invention.
第一の吸水性樹脂粉末に水性液を添加、または第一の吸水性樹脂粉末を水性液に添加してから混合を始めるまでの時間は、時間が長くなると水性液と第一の吸水性樹脂粉末との均一な混合が困難となり巨大な凝集物となるので、できるだけ早く、通常は1分以内、好ましくは30秒以内に混合を始める方がよい。さらには、第一の吸水性樹脂粉末を撹拌しているところに水性液を添加して混合してもよく、または第一の吸水性樹脂粉末を攪拌中の水性液に添加してもよく、あるいは第一の吸水性樹脂粉体と水性液が連続的に投入され、混合され、連続的に本発明に用いられる水性液を含む第一の吸水性樹脂粉末が製造される場合もある。 The time from the addition of the aqueous liquid to the first water-absorbent resin powder or the addition of the first water-absorbent resin powder to the aqueous liquid until the start of mixing increases with time. Since uniform mixing with the powder becomes difficult and large agglomerates are formed, it is better to start mixing as soon as possible, usually within 1 minute, preferably within 30 seconds. Further, the aqueous liquid may be added and mixed while stirring the first water absorbent resin powder, or the first water absorbent resin powder may be added to the aqueous liquid being stirred, Alternatively, the first water-absorbent resin powder and the aqueous liquid may be continuously added and mixed to produce the first water-absorbent resin powder containing the aqueous liquid used in the present invention continuously.
本発明において、工程(b)での水性液を含む第一の吸水性樹脂粉末と第二の吸水性樹脂粉末の混合は、特に制限はなく、水性液を含む第一の吸水性樹脂粉末と第二の吸水性樹脂粉末を混合した後に巨大な凝集物がなく均一に混合できればよい。通常は水性液を含む第一の吸水性樹脂粉末に対して第二の吸水性樹脂粉末を添加するが、第二の吸水性樹脂粉末に対して水性液を含む第一の吸水性樹脂粉末を添加しても構わない。水性液を含む第一の吸水性樹脂粉末に第二の吸水性樹脂粉末を添加、あるいは水性液を含む第一の吸水性樹脂粉末を第二の吸水性樹脂粉末に添加してから混合を始めるまでの時間は、時間が長くなると、水性液を含む第一の吸水性樹脂粉末と第二の吸水性樹脂粉末との均一な混合が困難となり、巨大な凝集物ができ、本発明の目的とする吸水性樹脂造粒物である混合物を得ることが出来ないので、通常は1分以内、好ましくは30秒以内に混合を始めるのがよい。また水性液を含む第一の吸水性樹脂粉末を撹拌しているところに第二の吸水性樹脂粉末を添加して混合してもよく、さらには水性液を含む第一の吸水性樹脂粉末と第二の吸水性樹脂粉末が連続的に投入され、混合され、連続的に本発明の吸水性樹脂造粒物が製造される場合もある。 In the present invention, the mixing of the first water absorbent resin powder containing the aqueous liquid and the second water absorbent resin powder in step (b) is not particularly limited, and the first water absorbent resin powder containing the aqueous liquid and It is only necessary that after the second water-absorbing resin powder is mixed, there is no huge aggregate and it can be mixed uniformly. Usually, the second water absorbent resin powder is added to the first water absorbent resin powder containing the aqueous liquid, but the first water absorbent resin powder containing the aqueous liquid is added to the second water absorbent resin powder. You may add. Add the second water absorbent resin powder to the first water absorbent resin powder containing the aqueous liquid, or add the first water absorbent resin powder containing the aqueous liquid to the second water absorbent resin powder and start mixing. The time until the time becomes longer, it becomes difficult to uniformly mix the first water-absorbent resin powder containing the aqueous liquid and the second water-absorbent resin powder, and a huge aggregate is formed. Since it is not possible to obtain a mixture that is a water-absorbent resin granulated product, the mixing is usually started within 1 minute, preferably within 30 seconds. Further, the second water-absorbing resin powder may be added and mixed while stirring the first water-absorbing resin powder containing the aqueous liquid, and further, the first water-absorbing resin powder containing the aqueous liquid and In some cases, the second water absorbent resin powder is continuously charged and mixed to continuously produce the water absorbent resin granulated product of the present invention.
本発明で前記水性液の混合する工程(a)、および前記第二の吸水性樹脂粉末を混合する工程(b)が60分以内であることが好ましい。 In the present invention, the step (a) of mixing the aqueous liquid and the step (b) of mixing the second water absorbent resin powder are preferably within 60 minutes.
前記工程(a)または前記工程(b)の混合時間は特に制限はないが、混合時間が長くなると第一の吸水性樹脂粉末および/または第二の吸水性樹脂粉末の劣化がおきるので、通常10分以内、好ましくは5分以内、より好ましくは1分以内がよい。混合を長時間続けると、加圧下吸水倍率の低下など、吸水性樹脂の劣化を生じる場合がある。 The mixing time in the step (a) or the step (b) is not particularly limited. However, if the mixing time is long, the first water-absorbing resin powder and / or the second water-absorbing resin powder is deteriorated. Within 10 minutes, preferably within 5 minutes, more preferably within 1 minute. If mixing is continued for a long time, the water-absorbent resin may be deteriorated, such as a decrease in water absorption capacity under pressure.
前記工程(a)または前記工程(b)の混合が達成できるのであれば、用いる混合機は特に限定されないが、容器固定型混合機、中でも、機械攪拌型混合機が好ましい。該混合機としては、例えば、タービュライザー(ホソカワミクロン社製)、レーディゲミキサー(レーディゲ社製)、およびモルタルミキサー(西日本試験機社製)などが挙げられる。バッチ式混合機および連続式混合機の何れでもよい。安定した性能が達成できる点でバッチ式混合機が好ましい場合もある。 The mixer to be used is not particularly limited as long as the mixing in the step (a) or the step (b) can be achieved, but a container-fixed mixer, among them, a mechanical stirring mixer is preferable. Examples of the mixer include a turbulizer (manufactured by Hosokawa Micron Co., Ltd.), a Redige mixer (manufactured by Redige Corporation), and a mortar mixer (manufactured by West Japan Tester Co., Ltd.). Either a batch type mixer or a continuous type mixer may be used. In some cases, a batch mixer is preferable in that stable performance can be achieved.
本発明の吸水性樹脂造粒物は、さらに乾燥して造粒強度を向上させることができる。前記工程(b)に次いで、さらに、該水性液を含む第一の吸水性樹脂粉末および第二の吸水性樹脂粉末の混合物を加熱乾燥する工程(c)を含む、ことが好ましい。 The water-absorbent resin granulated product of the present invention can be further dried to improve the granulation strength. After the step (b), it is preferable to further include a step (c) of heating and drying a mixture of the first water absorbent resin powder and the second water absorbent resin powder containing the aqueous liquid.
該混合物を加熱乾燥することで、微粉末はより強固に一体化され、一次粒子並みの強度に再生される。上記の様にして得られた、吸水性樹脂造粒物乾燥体は耐衝撃性にも優れ、微粉末量が少ない優れた粒子状吸水剤である。本発明の吸水性樹脂造粒物乾燥体とは吸水性樹脂造粒物を後述する方法により加熱乾燥を行った吸水性樹脂造粒物のことであり、含水率等の範囲で規定されるものではない。本発明の吸水性樹脂造粒物の乾燥方法は特に限定されず、通常の乾燥機又は加熱炉が広く用いられるが、好ましくは40〜150℃、より好ましくは60〜100℃の範囲内で乾燥すると、吸水性樹脂造粒物の劣化が少なくなるので好ましい。乾燥時間としては、物性面から一定時間以上行うことが必要であり、通常は1分〜10時間、好ましくは3分〜3時間の範囲内が好ましい。 By heating and drying the mixture, the fine powder is more firmly integrated and regenerated to the same strength as the primary particles. The dried water-absorbent-resin granulated product obtained as described above is an excellent particulate water-absorbing agent having excellent impact resistance and a small amount of fine powder. The dried water-absorbent resin granulated product of the present invention is a water-absorbent resin granulated product obtained by heat-drying the water-absorbent resin granulated product by a method described later, and is specified in the range of moisture content and the like. is not. The drying method of the water-absorbent resin granulated product of the present invention is not particularly limited, and an ordinary dryer or a heating furnace is widely used, but preferably dried within a range of 40 to 150 ° C, more preferably 60 to 100 ° C. Then, since deterioration of a water absorbent resin granulated material decreases, it is preferable. As the drying time, it is necessary to carry out for a certain time or more from the viewpoint of physical properties, and it is usually 1 minute to 10 hours, preferably 3 minutes to 3 hours.
さらに、本発明では、前記工程(b)ないし前記工程(c)に次いで、該水性液を含む第一の吸水性樹脂粉末および第二の吸水性樹脂粉末との混合物ないしその乾燥物を、破砕および分級する工程(d)を含むことが好ましい。破砕とは大きすぎる造粒(例えば、850μm以上の粒子)を破壊する操作であり、全体または粗大粒子のみで行ってもよい。 Furthermore, in the present invention, following the steps (b) to (c), the mixture of the first water-absorbent resin powder and the second water-absorbent resin powder containing the aqueous liquid or the dried product thereof are crushed. And classification (d) is preferably included. The crushing is an operation for breaking granulation that is too large (for example, particles having a size of 850 μm or more), and may be performed entirely or only with coarse particles.
上記のようにして得られた吸水性樹脂造粒物あるいは吸水性樹脂造粒物乾燥体の粉砕分級物に、必要に応じて前述の表面近傍の架橋を行ってもよい。すなわち、吸水性樹脂粉末を前記した本発明の造粒方法によって吸水性樹脂造粒物とし、さらに加熱乾燥して吸水性樹脂造粒物乾燥体とすることで、微粉末含有量の少ない粒子状吸水剤を得、該吸水性樹脂造粒物あるいは吸水性樹脂造粒物乾燥体に前記の表面架橋処理をさらに行って粒子状吸水剤を製造してもよい。 The water-absorbent resin granulated product obtained as described above or the ground and classified product of the dried water-absorbent resin granulated product may be cross-linked in the vicinity of the surface as necessary. That is, the water-absorbent resin powder is made into a water-absorbent resin granulated product by the granulation method of the present invention described above, and further dried by heating to obtain a dried water-absorbent resin granulated product. A water-absorbing agent may be obtained, and the water-absorbing resin granulated product or the dried water-absorbing resin granulated product may be further subjected to the surface crosslinking treatment to produce a particulate water-absorbing agent.
以上、本発明にかかる粒子状吸水剤とは前記の吸水性樹脂造粒物および/または吸水性樹脂造粒物乾燥体であり、さらには該吸水性樹脂造粒物および/または吸水性樹脂造粒物乾燥体に前記の表面架橋処理を施したものであっても良い。 As mentioned above, the particulate water-absorbing agent according to the present invention is the water-absorbent resin granulated product and / or dried water-absorbent resin granulated product, and further, the water-absorbent resin granulated product and / or the water-absorbent resin granulated product. The dried granular material may have been subjected to the above surface cross-linking treatment.
なお、本発明の方法と異なり、二種類の吸水性樹脂粉末(第一,第二)を予め混合して水性液と混合する場合(一括造粒)、本発明の特徴である、強い造粒強度の吸水性樹脂造粒物および/または吸水性樹脂造粒物乾燥体を得ることが困難になり、吸水性樹脂微粉末が少ない粒子状吸水剤を得られない。 Unlike the method of the present invention, when two types of water-absorbent resin powders (first and second) are mixed in advance and mixed with an aqueous liquid (collective granulation), strong granulation is a feature of the present invention. It becomes difficult to obtain a strong water-absorbent resin granulated product and / or dried water-absorbent resin granulated product, and a particulate water-absorbing agent with a small amount of water-absorbent resin fine powder cannot be obtained.
それに対して、第一の吸水性樹脂粉末および水性液を混合した後に、該水性液を含む第一の吸水性樹脂粉末と第二の吸水性樹脂粉末を混合する方法により、特殊な混合機の必要もなく、第一の吸水性樹脂粉末と第二の吸水性樹脂粉末の造粒物である微粉末が少ない粒子状吸水剤が得られる。なお、本発明における粒子状吸水剤とは、100%が複数の吸水性樹脂粉末の凝集体(造粒物)である必要はなく、複数の吸水性樹脂粉末の凝集体よりなるもの(造粒物)と吸水性樹脂粉末単体(一次粒子)よりなるものの混合物であってもよい。複数の吸水性樹脂粉末の凝集体(造粒物)であることは光学顕微鏡によって個々の粒子が形状を保ったまま複数集まり凝集している事実や、吸液時に複数の不連続粒子として膨潤する事実で確認できる。 On the other hand, by mixing the first water-absorbing resin powder and the aqueous liquid and then mixing the first water-absorbing resin powder containing the aqueous liquid and the second water-absorbing resin powder, a special mixer There is no need to obtain a particulate water-absorbing agent with a small amount of fine powder, which is a granulated product of the first water-absorbent resin powder and the second water-absorbent resin powder. In the present invention, the particulate water-absorbing agent does not need to be an aggregate (granulated product) of a plurality of water-absorbent resin powders, but is composed of an aggregate of a plurality of water-absorbent resin powders (granulated). Or a mixture of the water-absorbent resin powder alone (primary particles). The fact that it is an aggregate (granulated product) of a plurality of water-absorbent resin powders means that a plurality of individual particles are aggregated and aggregated while maintaining the shape by an optical microscope, and swells as a plurality of discontinuous particles during liquid absorption. It can be confirmed by fact.
なお、本発明の粒子状吸水剤である第一の吸水性樹脂粉末と第二の吸水性樹脂粉末との造粒物は、用いた原料の吸水性樹脂粉末の重量平均粒子径の増大、および/または、微粉末の低減を生じることで、上記造粒物が生じていることを確認できる。 The granulated product of the first water-absorbent resin powder and the second water-absorbent resin powder, which is the particulate water-absorbing agent of the present invention, has an increased weight average particle diameter of the water-absorbent resin powder used as a raw material, and It can be confirmed that the granulated product is generated by reducing the fine powder.
(4)本発明の粒子状吸水剤
すなわち、本発明の粒子状吸水剤の生理食塩水に対する無加圧下吸収倍率(CRC)は27g/g以上、好ましくは30g/g以上、33g/g以上、36g/g以上とされる。無加圧下吸収倍率が20g/g未満である場合にはおむつに使用した場合に高物性を示さないおそれがある。また、上限は特には問わないが、製造上の困難によるコストアップから60g/g程度で十分である。
(4) The particulate water-absorbing agent of the present invention That is, the absorption capacity without load (CRC) with respect to physiological saline of the particulate water-absorbing agent of the present invention is 27 g / g or more, preferably 30 g / g or more, 33 g / g or more, It is set to 36 g / g or more. When the absorption capacity under no pressure is less than 20 g / g, there is a possibility that high physical properties are not exhibited when used for diapers. Moreover, although an upper limit is not ask | required in particular, about 60 g / g is enough from the cost increase by the difficulty on manufacture.
本発明の1.9kPa荷重下での加圧下吸収倍率(AAP)は20g/g以上、より好ましくは22g/g以上、さらに好ましくは24g/g以上、特に好ましくは26g/g以上とされる。加圧下吸収倍率が20g/g未満である場合にはおむつに使用した場合に高物性を示さないおそれがある。また、上限は特には問わないが、製造上の困難によるコストアップから40g/g程度で十分である。 The absorption capacity under load (AAP) under a 1.9 kPa load of the present invention is 20 g / g or more, more preferably 22 g / g or more, still more preferably 24 g / g or more, and particularly preferably 26 g / g or more. If the absorption capacity under pressure is less than 20 g / g, high physical properties may not be exhibited when used for diapers. Moreover, although an upper limit is not ask | required in particular, about 40 g / g is enough from the cost increase by the difficulty on manufacture.
すなわち、本発明の粒子状吸水剤の重量平均粒子径(D50)は200〜800μm、より好ましくは250〜600μm、さらに好ましくは300〜500μmであり、150μm未満の微粉末の量が実施例で説明する耐衝撃性テスト前で0〜5重量%以下、さらに3重量%以下、特に1重量%以下、耐衝撃性テスト後でも0〜5重量%以下、さらに3重量%以下と非常に少ない。対数標準偏差(σζ)は0.25〜0.50、好ましくは0.30〜0.45に制御される。 That is, the weight average particle diameter (D50) of the particulate water-absorbing agent of the present invention is 200 to 800 μm, more preferably 250 to 600 μm, still more preferably 300 to 500 μm, and the amount of fine powder less than 150 μm is explained in the examples. Before the impact resistance test, 0 to 5% by weight or less, further 3% by weight or less, particularly 1% by weight or less, and even after the impact resistance test, 0 to 5% by weight or less, and further 3% by weight or less. The logarithmic standard deviation (σζ) is controlled to 0.25 to 0.50, preferably 0.30 to 0.45.
上記の粒子状吸水剤に、消毒剤、抗菌剤、香料、各種の無機粉末、発泡剤、顔料、染料、親水性短繊維、肥料、酸化剤、還元剤、水、塩類等を0〜30重量%、好ましくは0〜5重量%の範囲で添加し、これにより、種々の機能を付与させることもできる。本発明の粒子状吸水剤は、従来公知の各種吸水性樹脂の用途に適用できるが、微粉末が少なく、加圧下の吸収特性や吸収速度に優れているため、これらの性能を重視される紙オムツや生理用ナプキン、失禁パッド等の吸収体を含む衛生材料や廃液固化剤、止水剤等の吸水性物品に好適に使用できる。 Disinfectant, antibacterial agent, fragrance, various inorganic powders, foaming agent, pigment, dye, hydrophilic short fiber, fertilizer, oxidizing agent, reducing agent, water, salt, etc. in the above particulate water-absorbing agent 0-30 weight %, Preferably in the range of 0 to 5% by weight, whereby various functions can be imparted. The particulate water-absorbing agent of the present invention can be applied to the use of various conventionally known water-absorbing resins, but it has few fine powders and is excellent in absorption characteristics and absorption speed under pressure. It can be suitably used for hygienic materials including absorbent materials such as diapers, sanitary napkins, and incontinence pads, and water-absorbing articles such as waste liquid solidifying agents and water-stopping agents.
(実施の形態2)
他の実施形態として、本発明に係る吸水性樹脂造粒物の製造方法は、吸水性樹脂粒子と水性液とを混合することにより吸水性樹脂含水物を得る水性液混合工程と、上記吸水性樹脂含水物と微粒子と混合することにより吸水性樹脂含水組成物を得る微粒子混合工程と、上記吸水性樹脂含水組成物を硬化する硬化工程および/または上記吸水性樹脂含水組成物を乾燥する乾燥工程と、を備える。なお、当該実施形態に係る製造方法を、便宜上「一括造粒法」と称する。以下、上記各工程について説明する。
(Embodiment 2)
As another embodiment, a method for producing a water-absorbent resin granulated product according to the present invention includes an aqueous liquid mixing step of obtaining a water-absorbent resin hydrate by mixing water-absorbent resin particles and an aqueous liquid, and Fine particle mixing step for obtaining a water-absorbing resin water-containing composition by mixing a resin water-containing material and fine particles, a curing step for curing the water-absorbing resin water-containing composition and / or a drying step for drying the water-absorbing resin water-containing composition And comprising. In addition, the manufacturing method according to the embodiment is referred to as “batch granulation method” for convenience. Hereafter, each said process is demonstrated.
<水性液混合工程>
水性液混合工程は、吸水性樹脂粒子と水性液とを混合することにより吸水性樹脂含水物を得る工程である。当該工程により、水性液の作用によって吸水性樹脂粒子を造粒し、吸水性樹脂含水物を得ることができる。
<Aqueous liquid mixing process>
The aqueous liquid mixing step is a step of obtaining a water-absorbing resin hydrate by mixing the water-absorbing resin particles and the aqueous liquid. By this step, the water-absorbent resin particles can be obtained by granulating the water-absorbent resin particles by the action of the aqueous liquid.
本発明の吸水性樹脂粒子とは、従来から知られている吸水性樹脂のことであり、例えばイオン交換水中において50倍から1000倍という多量の水を吸水し、アニオン性、ノニオン性、またはカチオン性の水不溶性ヒドロゲルを形成する従来公知の架橋重合体のことである。 The water-absorbent resin particles of the present invention are conventionally known water-absorbent resins. For example, the water-absorbent resin particles absorb 50 to 1000 times as much water as ion-exchanged water, and are anionic, nonionic, or cationic. It is a conventionally known crosslinked polymer that forms a water-insoluble hydrogel.
また、上記吸水性樹脂粒子としては、水膨潤性水不溶性であることが必須であり、該吸水性樹脂粒子中の未架橋の水可溶性成分(水溶性高分子)が、好ましくは0重量%以上30重量%以下、より好ましくは1重量%以上25重量%以下、さらに好ましくは5重量%以上20重量%以下、特に好ましくは5重量%以上15重量%以下のものが用いられる。 The water-absorbing resin particles must be water-swellable and water-insoluble, and the water-absorbing resin particles contain an uncrosslinked water-soluble component (water-soluble polymer), preferably 0% by weight or more. 30% by weight or less, more preferably 1% by weight or more and 25% by weight or less, further preferably 5% by weight or more and 20% by weight or less, and particularly preferably 5% by weight or more and 15% by weight or less.
これらは、一般に単量体溶液の状態で重合され、必要に応じて該重合体を乾燥し、乾燥の前および/または後で通常粉砕して得られたものである。なお、本発明においては、吸水性樹脂粒子を単に吸水性樹脂と称することもある。 These are generally obtained by polymerizing in the form of a monomer solution, drying the polymer as necessary, and usually pulverizing it before and / or after drying. In the present invention, the water absorbent resin particles may be simply referred to as a water absorbent resin.
上記架橋重合体の具体例としては、部分中和架橋ポリアクリル酸重合体(米国特許第4625001号明細書、米国特許第4654039号明細書、米国特許第5250640号明細書、米国特許第5275773号明細書、欧州特許第456136号明細書等)、架橋されて部分的に中和された澱粉−アクリル酸グラフトポリマー(米国特許第4076663号明細書)、イソブチレン−マレイン酸共重合体(米国特許第4389513号明細書)、酢酸ビニル−アクリル酸共重合体のケン化物(米国特許第4124748号明細書)、アクリルアミド(共)重合体の加水分解物(米国特許第3959569号明細書)、アクリロニトリル重合体の加水分解物(米国特許第3935099号明細書)等が挙げられる。 Specific examples of the crosslinked polymer include partially neutralized crosslinked polyacrylic acid polymers (US Pat. No. 4,462,001, US Pat. No. 4,654,039, US Pat. No. 5,250,640, US Pat. No. 5,275,773). , European Patent No. 456136, etc.), cross-linked and partially neutralized starch-acrylic acid graft polymer (US Pat. No. 4,076,663), isobutylene-maleic acid copolymer (US Pat. No. 4,389,513) Saponification of vinyl acetate-acrylic acid copolymer (US Pat. No. 4,124,748), hydrolyzate of acrylamide (co) polymer (US Pat. No. 3,959,569), acrylonitrile polymer Examples thereof include hydrolysates (US Pat. No. 3,935,099).
本発明で用いる吸水性樹脂粒子はアクリル酸および/またはその塩を含む水溶性不飽和単量体を重合して得られるアクリル酸および/またはアクリル酸塩を構成単位として含むポリアクリル酸(塩)系架橋重合体からなる吸水性樹脂の粒子であることが好ましい。上記単量体を用いると、得られる吸水性樹脂粒子の吸水性能や安全性がより一層向上するので好ましい。 The water-absorbent resin particles used in the present invention are polyacrylic acid (salt) containing acrylic acid and / or acrylate as a structural unit obtained by polymerizing a water-soluble unsaturated monomer containing acrylic acid and / or a salt thereof. The particles are preferably water-absorbent resin particles made of a crosslinked polymer. Use of the monomer is preferable because the water absorption performance and safety of the resulting water absorbent resin particles are further improved.
上記ポリアクリル酸(塩)系架橋重合体とは、全構成単位中、(架橋剤を除く)アクリル酸および/またはその塩を50モル%以上100モル%以下、好ましくは70モル%以上100モル%以下、より好ましくは90モル%以上100モル%以下含む単量体を重合して得られる架橋重合体である。また、重合体中の酸基は、その50モル%以上90モル%以下が中和されていることが好ましく、60モル%以上80モル%以下が中和されていることがより好ましい。塩としてはナトリウム、カリウム、リチウム等のアルカリ金属塩、アンモニウム塩、アミン塩などを例示する事ができる。塩を形成させるための中和は重合前に単量体の状態で行っても良いし、あるいは重合途中や重合後に重合体の状態で行っても良いし、それらを併用してもよい。 The above-mentioned polyacrylic acid (salt) -based crosslinked polymer means that acrylic acid and / or a salt thereof (excluding the crosslinking agent) is 50 mol% or more and 100 mol% or less, preferably 70 mol% or more and 100 mol in all constituent units. %, More preferably 90 mol% or more and a cross-linked polymer obtained by polymerizing a monomer containing 100 mol% or less. Moreover, it is preferable that 50 mol% or more and 90 mol% or less of the acid group in a polymer are neutralized, and it is more preferable that 60 mol% or more and 80 mol% or less are neutralized. Examples of the salt include alkali metal salts such as sodium, potassium and lithium, ammonium salts and amine salts. Neutralization for forming a salt may be performed in a monomer state before polymerization, or may be performed in a polymer state during polymerization or after polymerization, or may be used in combination.
上記ポリアクリル酸(塩)系架橋重合体としては、主成分として用いられる単量体(アクリル酸および/またはその塩)に併用して、必要により他の単量体を共重合させたものであってもよい。 The polyacrylic acid (salt) -based crosslinked polymer is used in combination with a monomer (acrylic acid and / or a salt thereof) used as a main component and, if necessary, copolymerized with another monomer. There may be.
他の単量体の具体例としては、メタアクリル酸、マレイン酸、ビニルスルホン酸、スチレンスルホン酸、2−(メタ)アクリルアミド−2−メチルプロパンスルホン酸、2−(メタ)アクリロイルオキシエタンスルホン酸、2−(メタ)アクリロイルオキシプロパンスルホン酸などのアニオン性不飽和単量体およびその塩;アクリルアミド、メタアクリルアミド、N−エチル(メタ)アクリルアミド、N−n−プロピル(メタ)アクリルアミド、N−イソプロピル(メタ)アクリルアミド、N,N−ジメチル(メタ)アクリルアミド、2−ヒドロキシエチル(メタ)アクリレート、2−ヒドロキシプロピル(メタ)アクリレート、メトキシポリエチレングリコール(メタ)アクリレート、ポリエチレングリコールモノ(メタ)アクリレート、ビニルピリジン、N−ビニルピロリドン、N−アクリロイルピペリジン、N−アクリロイルピロリジン、N−ビニルアセトアミドなどのノニオン性の親水基含有不飽和単量体;N,N−ジメチルアミノエチル(メタ)アクリレート、N,N−ジエチルアミノエチル(メタ)アクリレート、N,N−ジメチルアミノプロピル(メタ)アクリレート、N,N−ジメチルアミノプロピル(メタ)アクリルアミドおよびそれらの四級塩などのカチオン性不飽和単量体などを挙げることができる。 Specific examples of other monomers include methacrylic acid, maleic acid, vinyl sulfonic acid, styrene sulfonic acid, 2- (meth) acrylamide-2-methylpropane sulfonic acid, 2- (meth) acryloyloxyethane sulfonic acid Anionic unsaturated monomers such as 2- (meth) acryloyloxypropanesulfonic acid and salts thereof; acrylamide, methacrylamide, N-ethyl (meth) acrylamide, Nn-propyl (meth) acrylamide, N-isopropyl (Meth) acrylamide, N, N-dimethyl (meth) acrylamide, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, polyethylene glycol mono (meth) acrylate, Nonionic hydrophilic group-containing unsaturated monomers such as nylpyridine, N-vinylpyrrolidone, N-acryloylpiperidine, N-acryloylpyrrolidine and N-vinylacetamide; N, N-dimethylaminoethyl (meth) acrylate, N, N -Cationically unsaturated monomers such as diethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylamide and quaternary salts thereof Can do.
これらアクリル酸および/またはその塩以外の単量体の使用量は、全単量体中0モル%以上30モル%以下が好ましく、より好ましくは0モル%以上10モル%以下である。 The amount of the monomer other than acrylic acid and / or its salt is preferably 0 mol% or more and 30 mol% or less, more preferably 0 mol% or more and 10 mol% or less in the total monomers.
さらに、上記単量体組成物は、得られる架橋重合体の親水性を阻害しない程度に、上記不飽和単量体と共重合可能な他の疎水性不飽和単量体を含んでいてもよい。上記の共重合性モノマーとしては、具体的には、たとえば、メチル(メタ)アクリレート、エチル(メタ)アクリレート、ブチル(メタ)アクリレートなどの(メタ)アクリル酸エステル類;酢酸ビニル、プロピオン酸ビニルなど、酸基や水酸基やアミノ基を含有しない疎水性単量体;などが挙げられる。これら共重合性モノマーは、単独で用いてもよく、また、二種類以上を適宜混合して用いてもよい。 Further, the monomer composition may contain another hydrophobic unsaturated monomer copolymerizable with the unsaturated monomer to the extent that the hydrophilicity of the resulting crosslinked polymer is not inhibited. . Specific examples of the copolymerizable monomer include (meth) acrylic acid esters such as methyl (meth) acrylate, ethyl (meth) acrylate, and butyl (meth) acrylate; vinyl acetate, vinyl propionate, and the like. And a hydrophobic monomer containing no acid group, hydroxyl group or amino group. These copolymerizable monomers may be used alone or in combination of two or more.
本発明に用いられる吸水性樹脂を得るために上述の単量体を重合するに際しては、バルク重合や沈殿重合を行うことが可能であるが、性能面や重合の制御の容易さ、さらに膨潤ゲルの吸収特性の観点から、上記単量体を水溶液とすることによる水溶液重合や逆相懸濁重合を行うことが好ましい。 When polymerizing the above-mentioned monomer to obtain the water-absorbent resin used in the present invention, bulk polymerization or precipitation polymerization can be performed. However, performance and ease of control of polymerization, and swelling gel From the viewpoint of the absorption characteristics, it is preferable to perform aqueous solution polymerization or reverse phase suspension polymerization by using the monomer as an aqueous solution.
尚、上記単量体を水溶液とする場合の該水溶液(以下、単量体水溶液と称する)中の単量体の濃度は、水溶液の温度や単量体によって決まり、特に限定されるものではないが、10重量%以上70重量%以下の範囲内が好ましく、20重量%以上60重量%以下の範囲内がさらに好ましい。また、上記水溶液重合を行う際には、水以外の溶媒を必要に応じて併用してもよく、併用して用いられる溶媒の種類は、特に限定されるものではない。 When the monomer is an aqueous solution, the concentration of the monomer in the aqueous solution (hereinafter referred to as the monomer aqueous solution) is determined by the temperature of the aqueous solution and the monomer, and is not particularly limited. However, it is preferably within the range of 10% by weight to 70% by weight, and more preferably within the range of 20% by weight to 60% by weight. Moreover, when performing the said aqueous solution polymerization, you may use together solvents other than water as needed, and the kind of solvent used together is not specifically limited.
逆相懸濁重合とは、単量体水溶液を疎水性有機溶媒に懸濁させる重合法であり、例えば、米国特許第4093776号、同4367323号、同4446261号、同4683274号、同5244735号などの米国特許に記載されている。水溶液重合とは、分散溶媒を用いずに単量体水溶液を重合する方法であり、例えば、米国特許4625001号、同4873299号、同4286082号、同4973632号、同4985518号、同5124416号、同5250640号、同5264495号、同5145906号、同5380808号などの米国特許や、欧州特許0811636号、同0955086号、同0922717号などの欧州特許に記載されている。これら重合法に例示の単量体成分や、開始剤などを本発明に適用することもできる。 Reverse phase suspension polymerization is a polymerization method in which an aqueous monomer solution is suspended in a hydrophobic organic solvent. For example, U.S. Pat. Nos. 4,093,764, 4,367,323, 4,446,261, 4,683,274, and 5,244,735, etc. In U.S. Patents. The aqueous solution polymerization is a method of polymerizing an aqueous monomer solution without using a dispersion solvent. For example, U.S. Pat. Nos. 4,462,001, 4,873,299, 4,286,082, 4,973,632, 4,985,518, 5,124,416, No. 5,250,640, US Pat. No. 5,264,495, US Pat. No. 5,145,906 and US Pat. No. 5,380,808, and European patents such as European Patents 081636, 09555086, and 0922717. Monomer components and initiators exemplified in these polymerization methods can also be applied to the present invention.
水溶性重合の方法としては、双腕型ニーダー中で単量体水溶液を、得られる含水ゲルを砕きながら重合したり、所定の容器中駆動するベルト上に単量体水溶液を供給し、重合して得られたゲルをミートチョッパー等で粉砕する方法等が挙げられる。 As a water-soluble polymerization method, a monomer aqueous solution is polymerized while crushing the resulting hydrogel in a double-arm kneader, or a monomer aqueous solution is supplied onto a belt driven in a predetermined container to polymerize. And a method of pulverizing the obtained gel with a meat chopper or the like.
上記の重合を開始させる際には、例えば過硫酸カリウム、過硫酸アンモニウム、過硫酸ナトリウム、t−ブチルハイドロパーオキサイド、過酸化水素、2,2’−アゾビス(2−アミジノプロパン)二塩酸塩等のラジカル重合開始剤や、2−ヒドロキシ−2−メチル−1−フェニル−プロパン−1−オン等の光重合開始剤を用いることができる。 When starting the above polymerization, for example, potassium persulfate, ammonium persulfate, sodium persulfate, t-butyl hydroperoxide, hydrogen peroxide, 2,2′-azobis (2-amidinopropane) dihydrochloride, etc. A radical polymerization initiator or a photopolymerization initiator such as 2-hydroxy-2-methyl-1-phenyl-propan-1-one can be used.
さらに、これら重合開始剤の分解を促進する還元剤を併用し、両者を組み合わせることによりレドックス系開始剤とすることもできる。上記の開始剤としては、例えば、亜硫酸ナトリウム,亜硫酸水素ナトリウム等の(重)亜硫酸(塩)、L−アスコルビン酸(塩)、第一鉄塩等の還元性金属(塩)、アミン類等が挙げられるが、特に限定されるものではない。 Further, a reducing agent that promotes the decomposition of the polymerization initiator can be used in combination, and a redox initiator can be obtained by combining the two. Examples of the initiator include (bi) sulfurous acid (salt) such as sodium sulfite and sodium bisulfite, L-ascorbic acid (salt), reducing metal (salt) such as ferrous salt, amines, and the like. Although it is mentioned, it is not particularly limited.
これら重合開始剤の使用量は、全単量体に対して通常0.001モル%以上2モル%以下、好ましくは0.01モル%以上0.1モル%以下である。これら重合開始剤の使用量が0.001モル%未満の場合には、未反応の単量体が多くなり、従って、得られる吸水性樹脂や吸水剤中の残存単量体が増加するので好ましくない。一方、これら重合開始剤の使用量が2モル%を超える場合には、得られる吸水性樹脂や吸水剤中の水可溶成分量が増加するので好ましくない場合がある。 The amount of these polymerization initiators used is usually from 0.001 mol% to 2 mol%, preferably from 0.01 mol% to 0.1 mol%, based on all monomers. When the amount of these polymerization initiators used is less than 0.001 mol%, the amount of unreacted monomers increases, and therefore, the residual monomer in the resulting water-absorbent resin and water-absorbing agent increases, which is preferable. Absent. On the other hand, when the usage-amount of these polymerization initiators exceeds 2 mol%, since the amount of water-soluble components in the obtained water-absorbing resin or water-absorbing agent increases, it may not be preferable.
また、反応系に放射線、電子線、紫外線等の活性エネルギー線を照射することにより重合反応の開始を行ってもよいし、さらに、上記重合開始剤を併用してもよい。尚、上記重合反応における反応温度は、特に限定されるものではないが、反応系の上下限で15℃以上130℃以下の範囲が好ましく、20℃以上120℃以下の範囲がより好ましい。また、反応時間や重合圧力も特に限定されるものではなく、単量体や重合開始剤の種類、反応温度等に応じて適宜設定すればよい。 Further, the polymerization reaction may be initiated by irradiating the reaction system with active energy rays such as radiation, electron beam, and ultraviolet rays, and the above polymerization initiator may be used in combination. The reaction temperature in the polymerization reaction is not particularly limited, but the upper and lower limits of the reaction system are preferably in the range of 15 ° C. or higher and 130 ° C. or lower, and more preferably in the range of 20 ° C. or higher and 120 ° C. or lower. Further, the reaction time and the polymerization pressure are not particularly limited, and may be appropriately set according to the type of monomer or polymerization initiator, the reaction temperature, and the like.
上記架橋重合体は、架橋剤を使用しない自己架橋型のものであってもよいが、1分子中に2個以上の重合性不飽和基や、2個以上の反応性基を有する架橋剤を共重合または反応させたものが好ましい。 The crosslinked polymer may be of a self-crosslinking type that does not use a crosslinking agent, but a crosslinking agent having two or more polymerizable unsaturated groups or two or more reactive groups in one molecule. Those copolymerized or reacted are preferred.
上記架橋剤(別称;内部架橋剤)の具体例としては、例えば、N,N’−メチレンビス(メタ)アクリルアミド、(ポリ)エチレングリコールジ(メタ)アクリレート、(ポリ)プロピレングリコールジ(メタ)アクリレート、(エチレンオキサイド変性)トリメチロールプロパントリ(メタ)アクリレート、トリメチロールプロパンジ(メタ)アクリレート、グリセリントリ(メタ)アクリレート、(エチレンオキサイド変性)グリセリンアクリレートメタクリレート、ペンタエリスリトールテトラ(メタ)アクリレート、ジペンタエリスリトールヘキサ(メタ)アクリレート、N,N−ジアリルアクリルアミド、トリアリルシアヌレート、トリアリルイソシアヌレート、トリアリルホスフェート、トリアリルアミン、ジアリルオキシ酢酸、ビス(N−ビニルカルボン酸アミド)、(エチレンオキサイド変性)テトラアリロキシエタン、ポリ(メタ)アリロキシアルカン、(ポリ)エチレングリコールジグリシジルエーテル、グリセロールジグリシジルエーテル、エチレングリコール、ポリエチレングリコール、プロピレングリコール、グリセリン、ペンタエリスリトール、エチレンジアミン、ポリエチレンイミン、グリシジル(メタ)アクリレートなどを挙げることができる。 Specific examples of the crosslinking agent (also referred to as internal crosslinking agent) include, for example, N, N′-methylenebis (meth) acrylamide, (poly) ethylene glycol di (meth) acrylate, and (poly) propylene glycol di (meth) acrylate. , (Ethylene oxide modified) trimethylolpropane tri (meth) acrylate, trimethylolpropane di (meth) acrylate, glycerin tri (meth) acrylate, (ethylene oxide modified) glycerin acrylate methacrylate, pentaerythritol tetra (meth) acrylate, dipenta Erythritol hexa (meth) acrylate, N, N-diallylacrylamide, triallyl cyanurate, triallyl isocyanurate, triallyl phosphate, triallylamine, diallyloxyacetic acid Bis (N-vinylcarboxylic acid amide), (ethylene oxide modified) tetraallyloxyethane, poly (meth) allyloxyalkane, (poly) ethylene glycol diglycidyl ether, glycerol diglycidyl ether, ethylene glycol, polyethylene glycol, propylene glycol Glycerin, pentaerythritol, ethylenediamine, polyethyleneimine, glycidyl (meth) acrylate, and the like.
これらの内部架橋剤は1種のみ用いてもよいし2種以上使用してもよい。中でも、得られる吸水性樹脂粒子の吸水特性などから、2個以上の重合性不飽和基を有する化合物を内部架橋剤として必須に用いることが好ましく、その使用量としては全単量体に対して0.001モル%以上2モル%以下の範囲内であることが好ましく、0.005モル%以上0.5モル%以下の範囲内とすることがより好ましく、0.01モル%以上0.2モル%以下の範囲内とすることがさらに好ましい。上記内部架橋剤の使用量が0.001モル%よりも少ない場合、並びに、2モル%よりも多い場合には、十分な吸収特性が得られないおそれがある。 These internal crosslinking agents may be used alone or in combination of two or more. Among them, it is preferable to use a compound having two or more polymerizable unsaturated groups as an internal crosslinking agent from the viewpoint of water absorption properties of the water-absorbent resin particles obtained, and the amount used is based on the total amount of monomers. It is preferably within the range of 0.001 mol% to 2 mol%, more preferably within the range of 0.005 mol% to 0.5 mol%, and more preferably 0.01 mol% to 0.2 mol%. More preferably, it is within the range of mol% or less. When the amount of the internal cross-linking agent used is less than 0.001 mol% and more than 2 mol%, sufficient absorption characteristics may not be obtained.
上記内部架橋剤を用いて架橋構造を重合体内部に導入する場合には、上記内部架橋剤を、上記単量体の重合前あるいは重合途中、あるいは重合後、または中和後に反応系に添加するようにすればよい。 When a crosslinked structure is introduced into the polymer using the internal cross-linking agent, the internal cross-linking agent is added to the reaction system before, during or after the polymerization of the monomer, or after the polymerization or neutralization. What should I do?
尚、上記重合に際しては、反応系に、澱粉・セルロース、澱粉・セルロースの誘導体、ポリビニルアルコール、ポリアクリル酸(塩)、ポリアクリル酸(塩)架橋体等の親水性高分子0重量%以上50重量%以下(対単量体)や、その他0重量%以上10重量%以下の、炭酸(水素)塩、二酸化炭素、アゾ化合物、不活性有機溶媒等の各種発泡剤;澱粉;各種界面活性剤;キレート剤;次亜燐酸(塩)等の連鎖移動剤などを添加してもよい。 In the polymerization, the reaction system includes starch / cellulose, starch / cellulose derivatives, polyvinyl alcohol, polyacrylic acid (salt), polyacrylic acid (salt) cross-linked hydrophilic polymer 0 wt% or more and 50% or more. Various foaming agents such as carbonic acid (hydrogen) salts, carbon dioxide, azo compounds, inert organic solvents, etc. in weight percent or less (based on monomer) or other weights ranging from 0% to 10% by weight; starch; various surfactants Chelating agent; chain transfer agent such as hypophosphorous acid (salt) may be added.
上記重合によって得られた架橋重合体は、水溶液重合の場合、通常塊状であるため、重合時または重合後に粒子状にするために粉砕する。上記粉砕は、例えばローラー型カッターや、ギロチンカッター、スライサー、ロールカッター、シュレッダー、ハサミなどの各種の切断手段やこれらの組み合わせを用いて行うことができ、特に限定されるものではない。尚、逆相懸濁重合の場合、粒子状で重合するため、通常、粉砕は不要である。 In the case of aqueous solution polymerization, the crosslinked polymer obtained by the above polymerization is usually in the form of a lump, and is pulverized to form particles during or after the polymerization. The pulverization can be performed using various cutting means such as a roller cutter, a guillotine cutter, a slicer, a roll cutter, a shredder, a scissor, or a combination thereof, and is not particularly limited. In the case of reverse phase suspension polymerization, since it is polymerized in the form of particles, pulverization is usually unnecessary.
上記吸水性樹脂粒子は、上記架橋重合体が水溶液重合で得られたものでゲル状である場合、すなわち含水ゲル状架橋重合体である場合、該架橋重合体は、必要に応じて乾燥し、乾燥の前および/または後で通常粉砕されて吸水性樹脂とする。また、乾燥は通常80℃以上250℃以下、好ましくは100℃以上220℃以下、より好ましくは120℃以上200℃以下の温度範囲で行われる。乾燥時間は、重合体の表面積、含水率、および乾燥機の種類に依存し、目的とする含水率になるよう、例えば1分以上10時間以下などが選択される。 When the water-absorbent resin particles are in the form of gel obtained by the aqueous solution polymerization, the crosslinked polymer is dried as necessary, if it is a hydrogel crosslinked polymer, It is usually pulverized before and / or after drying to obtain a water absorbent resin. Moreover, drying is normally performed in the temperature range of 80 to 250 ° C., preferably 100 to 220 ° C., more preferably 120 to 200 ° C. The drying time depends on the surface area of the polymer, the water content, and the type of the dryer, and is selected from 1 minute to 10 hours, for example, so as to achieve the desired water content.
上記吸水性樹脂粒子は、このように含水ゲル状架橋重合体を粉砕して粒子状にしたものであってもよく、含水ゲル状架橋重合体を乾燥し、さらに粉砕や分級等を行って粒子状にしたものであってもよい。吸水性樹脂粒子の粒子径としては、特に限定されるものではないが、標準篩分級(JIS Z8801−1(2000)ないし相当品。以下、粒径は同様の操作で規定する)で規定される粒子径が850μm未満であることが好ましい。標準篩分級で規定される粒子径が850μm以上の場合は、造粒中に塊状物となりやすく、また、吸水性樹脂造粒物の吸水特性等の物性を低下させるため好ましくない。 The water-absorbent resin particles may be particles obtained by pulverizing the water-containing gel-like crosslinked polymer in this way, and the water-containing gel-like crosslinked polymer is dried and further pulverized, classified, etc. It may be a shape. The particle diameter of the water-absorbent resin particles is not particularly limited, but is defined by standard sieve classification (JIS Z8801-1 (2000) or equivalent. The particle diameter is defined in the same manner below). The particle diameter is preferably less than 850 μm. When the particle size defined by the standard sieve classification is 850 μm or more, it is not preferable because it tends to be a lump during granulation and the physical properties such as the water absorption property of the water absorbent resin granulation are deteriorated.
かかる吸水性樹脂の粒度としては、全体の粒度に対して、粒子径600μm以上850μm以下の粒子が0重量%以上、20重量%未満、300μm以上600μm以下が60重量%以上、200μm未満が20重量%未満であることが好ましい。粒子径600μm以上850μm以下の粒子が20重量%以上である場合や、300μm以上600μm以下の粒子が60重量%未満、200μm未満の粒子が20重量%以上の粒度の場合は、体液(尿や血液等)の吸収速度が著しく低下する虞があり、適当でない。 The particle size of the water-absorbent resin is 0% by weight or more and less than 20% by weight, particles having a particle size of 600 μm or more and 850 μm or less, 60% by weight or more and 60% by weight or less, and 20% by weight less than 200 μm. It is preferable that it is less than%. When the particle size is 600 μm or more and 850 μm or less is 20% by weight or more, or when the particle size is 300 μm or more and 600 μm or less is less than 60% by weight, and the particle size less than 200 μm is 20% by weight or more, body fluid (urine or blood Etc.) is not suitable because the absorption rate may be significantly reduced.
また、粒度分布の対数標準偏差(σζ)が0.25以上0.400以下の範囲であることが好ましく、0.270以上0.380以下の範囲がより好ましい。粒度分布の対数標準偏差(σζ)が0.250よりも小さい場合は、製造コストが著しく上昇するため、適当ではない。また、粒度分布の対数標準偏差(σζ)が0.400を超える場合は、造粒時の粒度分布が不均一になりやすく,造粒強度も安定しない為、本発明には適当でない。 The logarithmic standard deviation (σζ) of the particle size distribution is preferably in the range of 0.25 to 0.400, more preferably in the range of 0.270 to 0.380. When the logarithmic standard deviation (σζ) of the particle size distribution is smaller than 0.250, the manufacturing cost is remarkably increased, which is not appropriate. In addition, when the logarithmic standard deviation (σζ) of the particle size distribution exceeds 0.400, the particle size distribution at the time of granulation tends to be non-uniform and the granulation strength is not stable, which is not suitable for the present invention.
本発明で用いることができる吸水性樹脂粒子は、0.90重量%塩化ナトリウム水溶液に対する無加圧下吸収倍率が10g/g以上50g/g以下であることが好ましく、より好ましくは20g/g以上45g/g以下、さらに好ましくは25g/g以上45g/g以下である。0.90重量%塩化ナトリウム水溶液に対する無加圧吸収倍率が10g/gよりも小さいと、吸水性樹脂粒子を製造する場合に多くの架橋剤を有する必要があり、これによって前述した水可溶性成分が極端に少なくなり、造粒強度が低下するだけでなく、吸水性樹脂の吸収量が不十分であることにより、おむつ等の吸収体において、液の戻り量が増えるなど、ベタツキ感が生じる為、好ましくない。 The water-absorbent resin particles that can be used in the present invention preferably have an absorption capacity without load with respect to a 0.90% by weight sodium chloride aqueous solution of 10 g / g or more and 50 g / g or less, more preferably 20 g / g or more and 45 g. / G or less, more preferably 25 g / g or more and 45 g / g or less. When the pressureless absorption capacity with respect to the 0.90% by weight sodium chloride aqueous solution is smaller than 10 g / g, it is necessary to have many cross-linking agents when producing water-absorbing resin particles, and thus the above-mentioned water-soluble components are contained. Not only is it extremely reduced and the granulation strength is lowered, but also due to insufficient absorption of the water-absorbent resin, in the absorbent body such as diapers, the amount of liquid returned increases, resulting in a sticky feeling. It is not preferable.
また、0.90重量%塩化ナトリウム水溶液に対する無加圧吸水倍率が50g/gよりも大きいと、前述した水可溶性成分が増加し、造粒時に塊状になり易くなるだけでなく、吸水性樹脂粒子が吸液により膨潤したゲル粒子のゲル強度が低下する為、体圧などの圧力下におけるゲル粒子の変形が生じ、吸水性樹脂のゲル層体積が低下し、吸収体からの漏れを生じるおそれがある。 In addition, when the non-pressurized water absorption ratio with respect to the 0.90% by weight sodium chloride aqueous solution is larger than 50 g / g, the above-mentioned water-soluble components increase, and not only the water-soluble resin particles tend to become agglomerated during granulation. Since the gel strength of the gel particles swollen by the liquid absorption is reduced, the gel particles may be deformed under pressure such as body pressure, the gel layer volume of the water absorbent resin may be reduced, and leakage from the absorber may occur. is there.
本発明で用いることができる吸水性樹脂粒子は、0.90重量%塩化ナトリウム水溶液に対する1.9kPaでの加圧下吸収倍率が10g/g以上40g/g未満であることが好ましく、より好ましくは20g/g以上35g/g未満である。おむつ等吸収体の使用環境は、体圧などの圧力が常に掛かっており、0.90重量%塩化ナトリウム水溶液に対する1.9kPaでの加圧下吸収倍率が10g/gよりも小さい場合、吸水性樹脂の加圧下における吸収量が不十分であり、吸収体からの体液(尿や血液など)の漏れ及び/またはベタツキ感を生じるおそれがあり好ましくない。 The water-absorbent resin particles that can be used in the present invention preferably have an absorption capacity under pressure at 1.9 kPa with respect to a 0.90% by weight sodium chloride aqueous solution of 10 g / g or more and less than 40 g / g, more preferably 20 g. / G or more and less than 35 g / g. The use environment of the absorbent body such as a diaper is that the pressure such as body pressure is always applied, and when the absorption capacity under pressure at 1.9 kPa with respect to the 0.90 wt% sodium chloride aqueous solution is smaller than 10 g / g, the water absorbent resin The amount of absorption under pressure is insufficient, which may cause leakage of body fluid (such as urine and blood) and / or a sticky feeling from the absorber.
また、0.90重量%塩化ナトリウム水溶液に対する1.9kPaでの加圧下吸収倍率を40g/g以上に高める為には、吸収性樹脂の改良を必要とし、製造コストの上昇を招くが、造粒強度やおむつ使用時にそれに見合った効果は得られない為、0.90重量%塩化ナトリウム水溶液に対する1.9kPaでの加圧下吸収倍率を40g/g以上にする必要はない。 Further, in order to increase the absorption capacity under pressure at 1.9 kPa with respect to 0.90% by weight sodium chloride aqueous solution to 40 g / g or more, it is necessary to improve the absorbent resin, which causes an increase in production cost. Since the strength and the effect corresponding to the use of the diaper cannot be obtained, it is not necessary to make the absorption capacity under a load of 1.9 kPa with respect to the 0.90 wt% sodium chloride aqueous solution 40 g / g or more.
上記吸水性樹脂粒子は、特に限定されるものではないが、表面架橋されていることが好ましい。「表面架橋」とは、吸水性樹脂粒子表面の官能基(特にカルボキシル基)とそれらと反応しうる化合物(好ましくは有機架橋剤等)とを反応させることである。表面架橋を行うことによって、通液性等、吸水性樹脂に求められる諸特性をより好ましいものとすることができる。 The water-absorbent resin particles are not particularly limited, but are preferably surface-crosslinked. “Surface cross-linking” refers to reacting a functional group (particularly a carboxyl group) on the surface of water-absorbent resin particles with a compound capable of reacting with them (preferably an organic cross-linking agent or the like). By performing surface cross-linking, various properties required for a water-absorbing resin such as liquid permeability can be made more preferable.
表面架橋剤としては、吸水性樹脂粒子の有する官能基、特に、カルボキシル基と反応し、架橋構造を形成し得る有機架橋剤や多価金属化合物が挙げられる。特に好ましくは以下に挙げられる有機架橋剤が用いられる。例えば、エチレングリコール、ジエチレングリコール、プロピレングリコール、トリエチレングリコール、テトラエチレングリコール、ポリエチレングリコール、1,3−プロパンジオール、ジプロピレングリコール、2,2,4−トリメチル−1,3−ペンタンジオール、ポリプロピレングリコール、グリセリン、ポリグリセリン、2−ブテン−1,4−ジオール、1,3−ブタンジオール、1,4−ブタンジオール、1,5−ペンタンジオール、1,6−ヘキサンジオール、1,2−シクロヘキサンジメタノール、1,2−シクロヘキサノール、トリメチロールプロパン、ジエタノールアミン、トリエタノールアミン、ポリオキシプロピレン、オキシエチレン−オキシプロピレンブロック共重合体、ペンタエリスリトール、ソルビトール等の多価アルコール;エチレングリコールジグリシジルエーテル、ポリエチレングリコールジグリシジルエーテル、グリセロールポリグリシジルエーテル、ジグリセロールポリグリシジルエーテル、ポリグリセロールポリグリシジルエーテル、プロピレングリコールジグリシジルエーテル、ポリプロピレングリコールジグリシジルエーテル、グリシドール等のエポキシ化合物;エチレンジアミン、ジエチレントリアミン、トリエチレンテトラミン、テトラエチレンペンタミン、ペンタエチレンヘキサミン、ポリエチレンイミン等の多価アミン化合物や、それらの無機塩ないし有機塩(例えば、アジリジニウム塩等);2,4−トリレンジイソシアネート、ヘキサメチレンジイソシアネート等の多価イソシアネート化合物;1,2−エチレンビスオキサゾリン等の多価オキサゾリン化合物;尿素、チオ尿素、グアニジン、ジシアンジアミド、2−オキサゾリジノン等の炭酸誘導体;1,3−ジオキソラン−2−オン、4−メチル−1,3−ジオキソラン−2−オン、4,5−ジメチル−1,3−ジオキソラン−2−オン、4,4−ジメチル−1,3−ジオキソラン−2−オン、4−エチル−1,3−ジオキソラン−2−オン、4−ヒドロキシメチル−1,3−ジオキソラン−2−オン、1,3−ジオキサン−2−オン、4−メチル−1,3−ジオキサン−2−オン、4,6−ジメチル−1,3−ジオキサン−2−オン、1,3−ジオキソパン−2−オン等のアルキレンカーボネート化合物;エピクロロヒドリン、エピブロムヒドリン、α−メチルエピクロロヒドリン等のハロエポキシ化合物、および、その多価アミン付加物(例えばハーキュレス製カイメン:登録商標);γ−グリシドキシプロピルトリメトキシシラン、γ−アミノプロピルトリエトキシシラン等のシランカップリング剤;3−メチル−3−オキセタンメタノール、3−エチル−3−オキセタンメタノール、3−ブチル−3−オキセタンメタノール、3−メチル−3−オキセタンエタノール、3−エチル−3−オキセタンエタノール、3−ブチル−3−オキセタンエタノール、3−クロロメチル−3−メチルオキセタン、3−クロロメチル−3−エチルオキセタン、多価オキセタン化合物などのオキセタン化合物;等が挙げられる。これら表面架橋剤は、1種のみ用いてもよいし、2種以上を併用してもよい。中でも多価アルコールは、安全性が高く、吸水性樹脂粒子表面の親水性を向上させることができる点で好ましい。 Examples of the surface cross-linking agent include organic cross-linking agents and polyvalent metal compounds that can form a cross-linked structure by reacting with functional groups of water-absorbent resin particles, in particular, carboxyl groups. Particularly preferably, the following organic crosslinking agents are used. For example, ethylene glycol, diethylene glycol, propylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, 1,3-propanediol, dipropylene glycol, 2,2,4-trimethyl-1,3-pentanediol, polypropylene glycol, Glycerin, polyglycerol, 2-butene-1,4-diol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,2-cyclohexanedimethanol 1,2-cyclohexanol, trimethylolpropane, diethanolamine, triethanolamine, polyoxypropylene, oxyethylene-oxypropylene block copolymer, pentaerythritol, sorbitol Polyhydric alcohols of: ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerol polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, glycidol etc. Compound; polyvalent amine compounds such as ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, polyethyleneimine, and their inorganic or organic salts (for example, aziridinium salts); 2,4-tolylene Polyisocyanate compounds such as isocyanate and hexamethylene diisocyanate; 1,2-ethylene bi Polyvalent oxazoline compounds such as oxazoline; carbonic acid derivatives such as urea, thiourea, guanidine, dicyandiamide and 2-oxazolidinone; 1,3-dioxolan-2-one, 4-methyl-1,3-dioxolan-2-one, 4 , 5-dimethyl-1,3-dioxolan-2-one, 4,4-dimethyl-1,3-dioxolan-2-one, 4-ethyl-1,3-dioxolan-2-one, 4-hydroxymethyl- 1,3-dioxolan-2-one, 1,3-dioxan-2-one, 4-methyl-1,3-dioxan-2-one, 4,6-dimethyl-1,3-dioxan-2-one, Alkylene carbonate compounds such as 1,3-dioxopan-2-one; haloepoxidation of epichlorohydrin, epibromohydrin, α-methylepichlorohydrin, etc. , And polyvalent amine adducts thereof (for example, Hercules Kaimen: registered trademark); silane coupling agents such as γ-glycidoxypropyltrimethoxysilane and γ-aminopropyltriethoxysilane; 3-methyl-3- Oxetanemethanol, 3-ethyl-3-oxetanemethanol, 3-butyl-3-oxetanemethanol, 3-methyl-3-oxetaneethanol, 3-ethyl-3-oxetaneethanol, 3-butyl-3-oxetaneethanol, 3- Oxetane compounds such as chloromethyl-3-methyloxetane, 3-chloromethyl-3-ethyloxetane, and polyvalent oxetane compounds; These surface cross-linking agents may be used alone or in combination of two or more. Of these, polyhydric alcohols are preferred because they are highly safe and can improve the hydrophilicity of the surface of the water-absorbent resin particles.
上記表面架橋処理において、米国特許第5422405号公報にて提案されているように、カルボキシル基と反応し得る表面架橋剤が溶解度パラメータ(SP値)の互いに異なる第一表面架橋剤及び第二表面架橋剤を組み合わせてなる場合には、加圧下吸収倍率がさらに一層優れた吸収剤を得ることができる。上記の第一表面架橋剤は、カルボキシル基と反応可能な、溶解度パラメータが12.5(cal/cm3)1/2以上の化合物が好ましく、13.0(cal/cm3)1/2以上(上限23.4(cal/cm3)1/2)の化合物がより好ましい。上記の第二表面架橋剤は、カルボキシル基と反応可能な、溶解度パラメータが12.5(cal/cm3)1/2未満の化合物が好ましく、9.5(cal/cm3)1/2以上12.0(cal/cm3)1/2以下の範囲内の化合物がより好ましい。 In the surface cross-linking treatment, as proposed in US Pat. No. 5,422,405, the first surface cross-linking agent and the second surface cross-linking agent having different solubility parameters (SP values) as surface cross-linking agents capable of reacting with carboxyl groups. In the case of combining agents, an absorbent having an even better absorption capacity under pressure can be obtained. The first surface crosslinking agent is preferably a compound capable of reacting with a carboxyl group and having a solubility parameter of 12.5 (cal / cm 3 ) 1/2 or more, and 13.0 (cal / cm 3 ) 1/2 or more. A compound having an upper limit of 23.4 (cal / cm 3 ) 1/2 is more preferable. The second surface crosslinking agent is preferably a compound capable of reacting with a carboxyl group and having a solubility parameter of less than 12.5 (cal / cm 3 ) 1/2 , and 9.5 (cal / cm 3 ) 1/2 or more A compound within a range of 12.0 (cal / cm 3 ) 1/2 or less is more preferable.
表面架橋剤の使用量は、吸水性樹脂粒子の固形分100重量部に対して0.001重量部以上5重量部以下であることが好ましい。 The amount of the surface cross-linking agent used is preferably 0.001 to 5 parts by weight with respect to 100 parts by weight of the solid content of the water-absorbent resin particles.
吸水性樹脂粒子と表面架橋剤とを混合する際には、表面架橋剤の溶媒として水を用いることが好ましい。水の使用量は吸水性樹脂粒子の100重量部に対して、好ましくは0を超え20重量部以上、より好ましくは0.5重量部以上10重量部以下の範囲である。 When mixing the water-absorbent resin particles and the surface cross-linking agent, it is preferable to use water as a solvent for the surface cross-linking agent. The amount of water used is preferably more than 0 and 20 parts by weight or more, more preferably 0.5 parts by weight or more and 10 parts by weight or less, with respect to 100 parts by weight of the water-absorbent resin particles.
吸水性樹脂粒子と表面架橋剤とを混合する際には、必要に応じて、親水性有機溶媒(水性液体)を併用してもよい。上記の親水性有機溶媒としては、例えば、メチルアルコール、エチルアルコール、n−プロピルアルコール、イソプロピルアルコールなどの一価アルコール類;アセトン等のケトン類;ジオキサン、テトラヒドロフラン等のエーテル類;等が挙げられる。親水性有機溶媒の使用量は吸水性樹脂粒子の100重量部に対して、好ましくは20重量部以下、より好ましくは0重量部以上10重量部以下である。 When mixing the water-absorbent resin particles and the surface cross-linking agent, a hydrophilic organic solvent (aqueous liquid) may be used in combination as necessary. Examples of the hydrophilic organic solvent include monohydric alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, and isopropyl alcohol; ketones such as acetone; ethers such as dioxane and tetrahydrofuran; The amount of the hydrophilic organic solvent to be used is preferably 20 parts by weight or less, more preferably 0 parts by weight or more and 10 parts by weight or less with respect to 100 parts by weight of the water-absorbent resin particles.
さらに、混合性向上や反応性向上のため、界面活性剤、不活性無機粉末、有機酸(塩)、無機酸(塩)、苛性ソーダなど塩基性化合物を吸水性樹脂100重量部に0重量部以上5重量部以下で併用してもよい。 Furthermore, in order to improve mixing properties and reactivity, a basic compound such as a surfactant, an inert inorganic powder, an organic acid (salt), an inorganic acid (salt), or caustic soda is added in an amount of 0 part by weight or more to 100 parts by weight of the water absorbent resin. You may use together in 5 weight part or less.
吸水性樹脂粒子と表面架橋剤とを予め混合した後、次いで、その水溶液を吸水性樹脂に噴霧あるいは滴下混合する方法が好ましく、噴霧する方法がより好ましい。噴霧される液滴の大きさは、平均粒径で0.1μm以上300μm以下の範囲内が好ましく、0.1μm以上200μm以下の範囲がより好ましい。吸水性樹脂粒子と表面架橋剤とを混合する場合には、本発明の効果を妨げない範囲で、水不溶性微粒子粉体や活性界面剤を共存させてもよい。 After mixing the water absorbent resin particles and the surface cross-linking agent in advance, the method of spraying or dropping and mixing the aqueous solution onto the water absorbent resin is preferable, and the method of spraying is more preferable. The size of the droplets to be sprayed is preferably in the range of 0.1 μm or more and 300 μm or less, more preferably in the range of 0.1 μm or more and 200 μm or less in terms of average particle size. When mixing the water-absorbent resin particles and the surface cross-linking agent, a water-insoluble fine particle powder or an active surfactant may be allowed to coexist within a range not impeding the effects of the present invention.
上記吸水性樹脂粒子と表面架橋剤とを混合した後、さらに、加熱処理を行い、吸水性樹脂粒子の表面近傍を架橋させる。すなわち、吸水性樹脂粒子の表面近傍で架橋剤を反応させるには、架橋剤の反応性、製造装置の簡易性、生産性を考慮すると加熱処理を行うのが好ましい。加熱処理の処理温度は用いる表面架橋剤にもよるが、80℃以上250℃以下、さらには100℃以上200℃以下の範囲が好ましい。上記の加熱処理は通常の乾燥機又は加熱炉を用いて行うことができる。乾燥機としては、例えば、溝型混合乾燥機、ロータリー乾燥機、ディスク乾燥機、流動層乾燥機、気流型乾燥機、及び赤外線乾燥機等が挙げられる。 After mixing the water-absorbent resin particles and the surface cross-linking agent, heat treatment is further performed to cross-link the vicinity of the surface of the water-absorbent resin particles. That is, in order to cause the crosslinking agent to react in the vicinity of the surface of the water-absorbent resin particles, it is preferable to perform heat treatment in consideration of the reactivity of the crosslinking agent, the simplicity of the production apparatus, and the productivity. The treatment temperature of the heat treatment depends on the surface crosslinking agent used, but is preferably in the range of 80 ° C. to 250 ° C., more preferably 100 ° C. to 200 ° C. Said heat processing can be performed using a normal dryer or a heating furnace. Examples of the dryer include a groove-type mixing dryer, a rotary dryer, a disk dryer, a fluidized bed dryer, an airflow dryer, and an infrared dryer.
上記「水性液」とは、水や、水溶性金属塩類あるいは親水性有機溶剤、水溶性高分子、界面活性剤、水不溶性無機粒子を含んだ水溶液またはスラリーのことである。 The “aqueous liquid” refers to an aqueous solution or slurry containing water, a water-soluble metal salt or a hydrophilic organic solvent, a water-soluble polymer, a surfactant, and water-insoluble inorganic particles.
上記水性液としては特に限定されるものではないが、物性や造粒強度の面から、水性液中の水の割合は70重量%以上100重量%以下、好ましくは80重量%以上100重量%以下、より好ましくは90重量%以上100重量%以下の範囲内であり、少量の架橋剤(例えば、前記表面架橋剤)や界面活性剤を含んでいても良い。本発明の目的を達成する為には、水性液の温度は特に限定されないが、通常5℃以上で沸点以下、好ましくは20℃以上であり、100℃を超えても大きな変化がないため、通常、100℃以下で行われる。 Although it does not specifically limit as said aqueous liquid, From the surface of a physical property or granulation strength, the ratio of the water in an aqueous liquid is 70 to 100 weight%, Preferably it is 80 to 100 weight% More preferably, it is in the range of 90 wt% or more and 100 wt% or less, and may contain a small amount of a crosslinking agent (for example, the surface crosslinking agent) or a surfactant. In order to achieve the object of the present invention, the temperature of the aqueous liquid is not particularly limited, but is usually 5 ° C. or higher and the boiling point or lower, preferably 20 ° C. or higher. At 100 ° C. or lower.
上記水性液の使用量は吸水性樹脂粒子100重量部に対して、通常1重量部以上150重量部以下、好ましくは5重量部以上100重量部以下、より好ましくは5重量部以上50重量部以下、さらに好ましくは5重量部以上30重量部以下、最も好ましくは5重量部以上20重量部以下である。水性液の使用量が150重量部を超えると、塊状物が形成されやすくなり造粒物として扱うことが困難となる上、乾燥コストや物性低下等の面で不利である。一方、水性液の使用量が1重量部よりも少ない場合、造粒強度が不十分になり、最終製品において造粒の特性を発揮することができなくなるおそれがある。また、混合が不均一になり造粒物が得られないことがある。 The amount of the aqueous liquid used is usually 1 part by weight or more and 150 parts by weight or less, preferably 5 parts by weight or more and 100 parts by weight or less, more preferably 5 parts by weight or more and 50 parts by weight or less with respect to 100 parts by weight of the water absorbent resin particles. More preferably, it is 5 parts by weight or more and 30 parts by weight or less, and most preferably 5 parts by weight or more and 20 parts by weight or less. When the amount of the aqueous liquid used exceeds 150 parts by weight, a lump is easily formed and it is difficult to handle as a granulated product, and it is disadvantageous in terms of drying cost and physical property reduction. On the other hand, when the amount of the aqueous liquid used is less than 1 part by weight, the granulation strength becomes insufficient, and there is a possibility that the granulation characteristics cannot be exhibited in the final product. Moreover, mixing may become non-uniform | heterogenous and a granulated material may not be obtained.
吸水性樹脂粒子と水性液との混合は、従来公知の混合機を用いて行うことができる。用いる混合機は特に限定されないが、容器固定型混合機、中でも、機械攪拌型混合機が好ましい。例えば、円筒型混合機、スクリュー型混合機、スクリュー型押出機、タービュライザー、ナウター型混合機、V型混合機、リボン型混合機、双腕型ニーダー、流動式混合機、気流型混合機、回転円盤型混合機、ロールミキサー、転動式混合機、パドル型混合機、レーディゲミキサーなどを挙げることができる。また、上記混合機は、バッチ式混合機および連続式混合機の何れでもよい。安定した性能が達成できる点でバッチ式混合機が好ましい場合もある。 Mixing of the water-absorbent resin particles and the aqueous liquid can be performed using a conventionally known mixer. The mixer to be used is not particularly limited, but a container-fixed mixer, among them, a mechanical stirring mixer is preferable. For example, cylindrical mixer, screw mixer, screw extruder, turbulizer, nauter mixer, V mixer, ribbon mixer, double arm kneader, fluid mixer, airflow mixer Rotating disk type mixers, roll mixers, rolling mixers, paddle type mixers, Ladige mixers and the like. The mixer may be either a batch mixer or a continuous mixer. In some cases, a batch mixer is preferable in that stable performance can be achieved.
また、吸水性樹脂粒子に水性液を添加する方法は特に限定されるものではないが、造粒を効率的に行うため、吸水性樹脂粒子に水性液を均一に分布させることができる方法、例えば水性液をスプレー噴霧により上記混合機に投入する方法等が好ましく用いられる。 Further, the method of adding the aqueous liquid to the water-absorbent resin particles is not particularly limited, but in order to perform granulation efficiently, a method that can uniformly distribute the aqueous liquid to the water-absorbent resin particles, for example, A method of charging an aqueous liquid into the mixer by spraying is preferably used.
本明細書において、「吸水性樹脂含水物」とは、少なくとも吸水性樹脂粒子と水性液とが混合され、少なくとも水性液の一部が吸水性樹脂粒子内部に吸収されたものをいう。該吸水性樹脂含水物の温度は、30℃以上100℃以下、好ましくは40℃以上100℃以下、さらに好ましくは50℃以上100℃以下である。その他に混合可能な成分としては、水性液による吸水性樹脂の造粒を妨げるものでなければ特に限定されるものではない。例えば、吸水性樹脂の通液性を高める効果を有する水溶性多価金属塩や前記架橋剤、着色防止剤等を混合することができる。 In the present specification, the “water-absorbing resin hydrate” refers to a product in which at least a water-absorbing resin particle and an aqueous liquid are mixed and at least a part of the aqueous liquid is absorbed inside the water-absorbing resin particles. The temperature of the water-absorbent resin hydrous material is 30 ° C. or higher and 100 ° C. or lower, preferably 40 ° C. or higher and 100 ° C. or lower, more preferably 50 ° C. or higher and 100 ° C. or lower. Other components that can be mixed are not particularly limited as long as they do not interfere with the granulation of the water-absorbent resin by the aqueous liquid. For example, a water-soluble polyvalent metal salt having an effect of enhancing the liquid permeability of the water-absorbent resin, the cross-linking agent, the anti-coloring agent, and the like can be mixed.
上記水溶性多価金属塩としては、例えば塩化アルミニウム、ポリ塩化アルミニウム、硫酸アルミニウム、硝酸アルミニウム、ビス硫酸カリウムアルミニウム、ビス硫酸ナトリウムアルミニウム、カリウムミョウバン、アンモニウムミョウバン、ナトリウムミョウバン、アルミン酸ナトリウム、塩化カルシウム、硝酸カルシウム、塩化マグネシウム、硫酸マグネシウム、硝酸マグネシウム、塩化亜鉛、硫酸亜鉛、硝酸亜鉛、塩化ジルコニウム、硫酸ジルコニウム、硝酸ジルコニウムなどを用いることができる。 Examples of the water-soluble polyvalent metal salt include aluminum chloride, polyaluminum chloride, aluminum sulfate, aluminum nitrate, potassium aluminum sulfate, sodium aluminum bissulfate, potassium alum, ammonium alum, sodium alum, sodium aluminate, calcium chloride, Calcium nitrate, magnesium chloride, magnesium sulfate, magnesium nitrate, zinc chloride, zinc sulfate, zinc nitrate, zirconium chloride, zirconium sulfate, zirconium nitrate and the like can be used.
また、上記着色防止剤としては、例えば硫黄含有還元剤、アミノ多価カルボン酸またはその塩や、有機リン酸化合物またはその塩などのキレート剤、過酸化水素などを用いることができる。 Examples of the anti-coloring agent include a sulfur-containing reducing agent, an amino polyvalent carboxylic acid or a salt thereof, a chelating agent such as an organic phosphoric acid compound or a salt thereof, hydrogen peroxide, and the like.
上記吸水性樹脂含水物は、第一の吸水性樹脂粒子と水性液とを混合した系に、さらに、第二の吸水性樹脂粒子を混合することによって得たものであってもよい。上記用語「第一の吸水性樹脂粒子」、「第二の吸水性樹脂粒子」とは、吸水性樹脂粒子と水性液との混合を二段階に分けて行うことを意味して用いたものであり、第一の吸水性樹脂粒子、第二の吸水性樹脂粒子としては、既に説明した吸水性樹脂粒子と同様のものを用いることができる。第一の吸水性樹脂粒子の種類と第二の吸水性樹脂の種類は、同じであってもよいし、異なっていてもよい。 The water-absorbing resin water-containing product may be obtained by further mixing the second water-absorbing resin particles in a system in which the first water-absorbing resin particles and the aqueous liquid are mixed. The terms “first water-absorbent resin particles” and “second water-absorbent resin particles” are used to mean mixing the water-absorbent resin particles and the aqueous liquid in two stages. In addition, as the first water-absorbing resin particles and the second water-absorbing resin particles, the same water-absorbing resin particles as already described can be used. The kind of 1st water absorbing resin particle and the kind of 2nd water absorbing resin may be the same, and may differ.
また、第一の吸水性樹脂粒子と第二の吸水性樹脂粒子の粒径は、同じであってもよいし、異なっていてもよい。例えば、第一の吸水樹脂粒子が上記微粉であり、第二の吸水性樹脂粒子が粗粒子であってもよい。このように、吸水性樹脂粒子と水性液との混合を二段階に分けて行う方法については後述する。 Moreover, the particle diameter of the 1st water absorbing resin particle and the 2nd water absorbing resin particle may be the same, and may differ. For example, the first water absorbent resin particles may be the fine powder, and the second water absorbent resin particles may be coarse particles. As described above, a method of mixing the water absorbent resin particles and the aqueous liquid in two stages will be described later.
以上説明した水性液混合工程によれば、吸水性樹脂粒子と水性液とを混合することにより、接着力が生じ、造粒が行なわれ、吸水性樹脂含水物を得ることができる。 According to the aqueous liquid mixing step described above, by mixing the water absorbent resin particles and the aqueous liquid, an adhesive force is generated, granulation is performed, and the water absorbent resin hydrate can be obtained.
<微粒子混合工程>
微粒子混合工程は、少なくとも吸水性樹脂含水物と微粒子とを混合することにより吸水性樹脂含水組成物を得る工程である。当該工程により、吸水性樹脂含水物の凝集が解かれ、比較的粒径の揃った造粒粒子(吸水性樹脂含水組成物)に変化するので、短時間で吸水性樹脂含水物に流動性を与えることができる。また、吸水性樹脂含水物の凝集が解かれることで粒子体積あたりの表面積が増加し、造粒粒子間の空隙が増加するため、より低温・短時間で硬化を行うことができる。
<Particle mixing process>
The fine particle mixing step is a step of obtaining a water-absorbing resin water-containing composition by mixing at least a water-absorbing resin water-containing material and fine particles. By this process, the water-absorbing resin hydrated material is agglomerated and changed to granulated particles having a relatively uniform particle size (water-absorbing resin hydrated composition). Can be given. Moreover, since the water-absorbent resin hydrous material is unaggregated, the surface area per particle volume increases and the voids between the granulated particles increase, so that curing can be performed at a lower temperature and in a shorter time.
本発明で使用される好ましい微粒子としては、例えば二酸化ケイ素、酸化アルミニウム、二酸化チタン、リン酸カルシウム、炭酸カルシウム、珪藻土、ベントナイト、ゼオライト、その他の金属酸化物等を挙げることができる。微粒子混合工程において吸水性樹脂含水物と混合される微粒子には、吸水性樹脂の微粒子は含まれない。また、キチン、キトサン、セルロース、パルプ、溶性デンプン等の有機微粒子を挙げることができ、無機微粒子、有機微粒子の何れも水不溶性若しくは水難溶性であることが好ましい。中でも、少量の添加量で効果が見られる、水不溶性無機微粒子が好ましく用いられる。上記水難溶性とは、23℃における水に対する溶解度が5重量%未満または1重量%以上の物質をいう。 Preferred fine particles used in the present invention include, for example, silicon dioxide, aluminum oxide, titanium dioxide, calcium phosphate, calcium carbonate, diatomaceous earth, bentonite, zeolite, and other metal oxides. The fine particles mixed with the water-absorbing resin hydrate in the fine particle mixing step do not include fine particles of the water-absorbing resin. Further, organic fine particles such as chitin, chitosan, cellulose, pulp, soluble starch and the like can be mentioned, and it is preferable that both inorganic fine particles and organic fine particles are water-insoluble or poorly water-soluble. Among these, water-insoluble inorganic fine particles that can be effective with a small addition amount are preferably used. The poor water solubility means a substance having a solubility in water at 23 ° C. of less than 5% by weight or 1% by weight or more.
これら微粒子の粒子径は、100μm以下であることが好ましく、50μm以下であることがより好ましく、10μm以下、下限は1nm程度であることが特に好ましい。粒子径が100μmを超えると、十分な造粒強度を得ることができなくなるだけでなく、吸水性樹脂含水物の凝集を十分に解くことができなくなる為、好ましくない。なお、上記粒子径は、コールターカウンター等で測定することができる。 The particle diameter of these fine particles is preferably 100 μm or less, more preferably 50 μm or less, and particularly preferably 10 μm or less, and the lower limit is about 1 nm. When the particle diameter exceeds 100 μm, it is not preferable because sufficient granulation strength cannot be obtained and aggregation of the water-absorbent resin-containing product cannot be sufficiently solved. The particle diameter can be measured with a Coulter counter or the like.
上記微粒子は、吸水性樹脂含水物に対して添加することを要する。すなわち、上記微粒子は、吸水性樹脂粒子と水性液とを混合した後の反応系に添加する必要がある。吸水性樹脂粒子と微粒子とを先に混合した後に水性液を添加すると、数mm程度の塊状物が形成されることがあるため好ましくない。 The fine particles need to be added to the water-absorbing resin hydrate. That is, the fine particles need to be added to the reaction system after mixing the water absorbent resin particles and the aqueous liquid. It is not preferable to add an aqueous liquid after first mixing the water-absorbent resin particles and the fine particles because a mass of about several mm may be formed.
上記微粒子を吸水性樹脂含水物に添加する方法としては特に限定されるものではない。例えば、上記微粒子を吸水性樹脂含水物に直接添加する方法や、上記微粒子を水性液や各種有機溶剤等に分散させたものを吸水性樹脂に噴霧または滴下する方法等を用いることができる。また、吸水性樹脂含水物は、上述のように、吸水性樹脂粒子と水性液とを混合した系に、さらに、吸水性樹脂粒子を混合することによって得たものであってもよいが、この場合、上記微粒子は後から添加する吸水性樹脂粒子に予め混合しておいても構わない。 The method of adding the fine particles to the water-absorbent resin hydrate is not particularly limited. For example, a method in which the fine particles are directly added to the water-absorbing resin hydrate, a method in which the fine particles are dispersed in an aqueous liquid, various organic solvents, or the like are sprayed or dropped onto the water-absorbing resin. Further, as described above, the water-absorbing resin hydrate may be obtained by further mixing the water-absorbing resin particles in a system in which the water-absorbing resin particles and the aqueous liquid are mixed. In this case, the fine particles may be mixed in advance with water absorbent resin particles to be added later.
なお、吸水性樹脂含水物と上記微粒子との混合は、例えば水性液混合工程の項で説明した従来公知の混合機を用いて行うことができる。 The water-absorbing resin hydrate and the fine particles can be mixed using, for example, a conventionally known mixer described in the section of the aqueous liquid mixing step.
本明細書において「吸水性樹脂含水組成物」とは、少なくとも吸水性樹脂含水物と、上記微粒子とが混合されたものをいう。吸水性樹脂含水物と上記微粒子とは結合していても構わない。他に混合可能な成分としては、上記微粒子を分散させるための水性液や、各種有機溶剤等が挙げられる。 In the present specification, the “water-absorbing resin water-containing composition” refers to a mixture of at least a water-absorbing resin water-containing material and the fine particles. The water-absorbing resin hydrate and the fine particles may be bonded. Other components that can be mixed include an aqueous liquid for dispersing the fine particles and various organic solvents.
上記吸水性樹脂含水組成物は、それ自体が流動性を有している。これは、本発明においては吸水性樹脂粒子と水性液とを混合した後、さらに上記微粒子を混合することによって、吸水性樹脂含水物の凝集が解かれ、塊状化が防止されることによる。そのため、後述する硬化工程および/または乾燥工程を円滑に行うことができる。流動性としては、特に限定されるものではないが、微粒子混合工程終了後、10分以内に測定した流下速度(後述する実施例に記載の測定方法に準ずる)が30秒以内であることが好ましい。 The water-absorbing resin water-containing composition itself has fluidity. This is because, in the present invention, after mixing the water-absorbent resin particles and the aqueous liquid, the fine particles are further mixed, whereby aggregation of the water-absorbent resin water-containing material is released and block formation is prevented. Therefore, the hardening process and / or drying process which are mentioned later can be performed smoothly. Although it does not specifically limit as fluidity | liquidity, it is preferable that the flow-down speed | rate (it applies to the measuring method as described in the Example mentioned later) measured within 10 minutes within 30 second after completion | finish of a microparticle mixing process. .
上記微粒子の量は、特に限定されるものではないが、全量の吸水性樹脂含水物100重量部に対して0.01重量部以上10重量部以下であることが好ましく、0.05重量部以上10重量部以下であることがより好ましく、0.1重量部以上10重量部以下であることが特に好ましい。 The amount of the fine particles is not particularly limited, but is preferably 0.01 parts by weight or more and 10 parts by weight or less, and 0.05 parts by weight or more with respect to 100 parts by weight of the total amount of the water-absorbent resin hydrate. It is more preferably 10 parts by weight or less, and particularly preferably 0.1 parts by weight or more and 10 parts by weight or less.
上記微粒子の量が0.01重量部未満だと、微粒子の量が少なすぎるため、吸水性樹脂粒子同士が接着している面に上記微粒子が十分に介在できず、過剰に成長した吸水性樹脂含水物の凝集を十分に解くことができないため好ましくない。一方、10重量部を超えると、吸水性樹脂としての性能(後述する加圧下吸水倍率等)を低下させるおそれがあり好ましくない。 If the amount of the fine particles is less than 0.01 parts by weight, the amount of fine particles is too small, so that the water-absorbent resin particles cannot sufficiently intervene on the surface where the water-absorbent resin particles are bonded to each other, and the water-absorbent resin grows excessively. It is not preferable because aggregation of the hydrated product cannot be sufficiently solved. On the other hand, if it exceeds 10 parts by weight, the performance as a water-absorbent resin (such as the water absorption capacity under pressure described later) may be lowered, which is not preferable.
以上説示した微粒子混合工程によれば、二酸化珪素等の微粒子の作用により、過剰に成長した吸水性樹脂含水物の凝集が解かれ、比較的粒径の揃った造粒粒子(吸水性樹脂含水組成物)に変化するので、短時間で吸水性樹脂含水物に流動性を与えることができる。また、吸水性樹脂含水物の凝集が解かれることで粒子体積あたりの表面積が増加し、造粒粒子間の空隙が増加するため、後述する硬化工程を円滑に進行させることができる。 According to the fine particle mixing process described above, the excessively grown water-absorbent resin hydrates are agglomerated by the action of fine particles such as silicon dioxide, and granulated particles having a relatively uniform particle size (water-absorbent resin water-containing composition). Therefore, fluidity can be imparted to the water-absorbing resin hydrated material in a short time. Moreover, since the surface area per particle volume increases and the voids between the granulated particles increase due to the agglomeration of the water-absorbent resin hydrated material, the curing step described later can be smoothly advanced.
図1は、水性液混合工程と微粒子混合工程の流れを示す模式図である。図1に示すように、吸水性樹脂粒子と水性液とを混合することにより、造粒が進行し、吸水性樹脂含水物が得られる。次いで、吸水性樹脂含水物および/またはその凝集体と微粒子とを混合することにより、凝集が解かれ、塊状体が形成されることなく、吸水性樹脂含水組成物が生成される。 FIG. 1 is a schematic diagram showing the flow of an aqueous liquid mixing step and a fine particle mixing step. As shown in FIG. 1, by mixing water absorbent resin particles and an aqueous liquid, granulation proceeds and a water absorbent resin hydrate is obtained. Next, the water-absorbing resin water-containing composition and / or the aggregates thereof and the fine particles are mixed to release aggregation and form a water-absorbing resin water-containing composition without forming a lump.
<硬化工程>
硬化工程とは、上記吸水性樹脂含水組成物を保温または加熱することにより硬化する工程である。上記「硬化」とは、吸水性樹脂含水組成物に含まれる水分(水性液)が、吸水性樹脂内部に吸収され、見かけ上吸水性樹脂表面が乾燥した状態になる現象のことをいう。なお、硬化が終了したか否かは、造粒粒子表面の硬度・流動性の向上によって判断することができる。
<Curing process>
The curing step is a step of curing by keeping or heating the water-absorbing resin water-containing composition. The term “curing” refers to a phenomenon in which water (aqueous liquid) contained in the water-absorbing resin water-containing composition is absorbed into the water-absorbing resin, and the surface of the water-absorbing resin is apparently dried. In addition, it can be judged by the improvement of the hardness and fluidity | liquidity of the granulated particle surface whether hardening was complete | finished.
<乾燥工程>
乾燥工程とは、上記吸水性樹脂含水組成物を保温または加熱することにより、乾燥する工程である。本明細書における「乾燥」とは、吸水性樹脂含水組成物に含まれる水分(水性液)が、吸水性樹脂含水組成物から外部へ飛散することをいい、蒸発も含まれる。
<Drying process>
A drying process is a process of drying by heat-retaining or heating the water-absorbing resin water-containing composition. In the present specification, “drying” means that water (aqueous liquid) contained in the water-absorbing resin water-containing composition is scattered from the water-absorbing resin water-containing composition to the outside, and includes evaporation.
上記硬化工程および上記乾燥工程は、ともに、上記吸水性樹脂含水組成物を加熱または保温する工程であるため、硬化工程と乾燥工程とは同時に行われ得る。一方、硬化工程のみ、または乾燥工程のみが行われる場合もある。 Since both the curing step and the drying step are steps for heating or keeping the water-absorbing resin water-containing composition, the curing step and the drying step can be performed simultaneously. On the other hand, only the curing process or only the drying process may be performed.
吸水性樹脂含水組成物を保温または加熱する方法としては、特に限定されるものではなく、例えば、無風乾燥機、バンド乾燥機、攪拌乾燥機、流動層乾燥機などの1種または2種以上の加熱装置を用いるような従来からの方法を好適に用いることができる。保温または加熱は、吸水性樹脂含水組成物を攪拌しながら行ってもよいし、後述するように静置して行ってもよい。硬化工程および/または乾燥工程を経て得られる吸水性樹脂造粒物の含水率は、好ましくは0.5重量%以上50重量%以下であり、さらに好ましくは2重量%以上30重量%以下、特に好ましくは5重量%以上20重量%以下である。 The method for keeping or heating the water-absorbent resin water-containing composition is not particularly limited, and examples thereof include one or more of airless dryers, band dryers, stirring dryers, fluidized bed dryers and the like. A conventional method using a heating device can be preferably used. The heat retention or heating may be performed while stirring the water-absorbing resin water-containing composition, or may be performed by standing as described later. The water content of the water-absorbent resin granulated product obtained through the curing step and / or the drying step is preferably 0.5% by weight to 50% by weight, more preferably 2% by weight to 30% by weight, particularly Preferably they are 5 weight% or more and 20 weight% or less.
また、加熱するため、または保温するための温度は、30℃以上250℃以下であることが好ましく、より好ましくは40℃以上200℃以下が好ましく、更に好ましくは50℃以上150℃以下である。加熱または保温する時間は1分以上2時間以内、好ましくは、1分以上1時間以内である。ここで、上記「加熱するため、または保温するための温度」とは、熱媒の温度のことである。マイクロ波を用いて乾燥する場合などのように熱媒温度が規定できない場合、材料の温度で規定する。 The temperature for heating or keeping the temperature is preferably 30 ° C. or higher and 250 ° C. or lower, more preferably 40 ° C. or higher and 200 ° C. or lower, and further preferably 50 ° C. or higher and 150 ° C. or lower. The time for heating or keeping warm is not less than 1 minute and not more than 2 hours, preferably not less than 1 minute and not more than 1 hour. Here, the above-mentioned “temperature for heating or keeping warm” refers to the temperature of the heat medium. If the temperature of the heating medium cannot be specified, such as when drying using microwaves, the temperature of the material is specified.
本発明に係る製造方法では、吸水性樹脂含水物と微粒子とを混合することにより得られた吸水性樹脂含水組成物が、流動性を有するだけでなく、低温・短時間で十分に硬化および/または乾燥することができることを新たに見出した。これは、吸水性樹脂含水物と混合された上記微粒子によって吸水性樹脂含水物の凝集が解かれることで、粒子体積あたりの表面積が増加し、造粒粒子間の空隙が増加するため、この空隙の存在により造粒粒子間に熱エネルギーが行き渡りやすくなることによると考えられる。 In the production method according to the present invention, the water-absorbing resin water-containing composition obtained by mixing the water-absorbing resin water-containing material and the fine particles has not only fluidity but also sufficiently cured and / or cured at a low temperature and in a short time. Or newly found that it can be dried. This is because the fine particles mixed with the water-absorbing resin water-containing material breaks up the water-absorbing resin water-containing material, thereby increasing the surface area per particle volume and increasing the space between the granulated particles. This is considered to be due to the fact that the heat energy easily spreads between the granulated particles.
一方、特許文献19に記載の技術では、高吸水性樹脂粉末とエチレン−アクリル酸共重合体の水中油滴型エマルションとを混合後、微粉末シリカを混合した場合、多数の塊状物が生じたことが開示されている。すなわち、吸水性樹脂粒子と水性液とを混合することにより吸水性樹脂含水物を得た後で、さらに上記微粒子を添加混合することによって、流動性を有し、効率よく加熱することができる吸水性樹脂含水組成物が得られることは、本発明によって初めて見い出された知見であるということができる。 On the other hand, in the technique described in Patent Document 19, a mixture of a superabsorbent resin powder and an oil-in-water emulsion of an ethylene-acrylic acid copolymer was mixed with fine powdered silica, resulting in a large number of lumps. It is disclosed. That is, after obtaining a water-absorbing resin water-containing product by mixing water-absorbing resin particles and an aqueous liquid, the water-absorbing water that has fluidity and can be efficiently heated by further adding and mixing the fine particles. It can be said that the water-soluble resin water-containing composition is obtained for the first time by the present invention.
なお、特許文献19に開示された発明は、エチレン−アクリル酸共重合体を添加することにより、造粒強度(粒子間の接着力)を向上させることを目的としている。仮に、微粉末シリカの添加目的が本発明と同じ(造粒粒子間に無機物が介在することによる接着力の低減)であると考えると、特許文献19では、エチレン−アクリル酸共重合体を添加することによる強固な造粒強度(必要以上の造粒強度)により、高吸水性樹脂粉末とエチレン−アクリル酸共重合体の水中油滴型エマルションとを混合後に添加した微粉末シリカが造粒粒子間に介在することが困難になり、多数の塊状物が生じる結果となったものと考えられる。 In addition, the invention disclosed in Patent Document 19 aims to improve the granulation strength (adhesion between particles) by adding an ethylene-acrylic acid copolymer. If it is considered that the purpose of addition of finely divided silica is the same as that of the present invention (reduction of adhesive force due to the presence of inorganic substances between granulated particles), Patent Document 19 adds an ethylene-acrylic acid copolymer. Due to strong granulation strength (granulation strength more than necessary), the fine powdered silica added after mixing the superabsorbent resin powder and the oil-in-water emulsion of ethylene-acrylic acid copolymer is granulated particles It is considered that it was difficult to intervene, resulting in a large number of lumps.
すなわち、特許文献19に記載の技術と本発明は全く技術思想の異なるものであり、吸水性樹脂粒子と水性液とを混合することにより吸水性樹脂含水物を得た後で、さらに微粒子を混合することによって、流動性を有し、効率よく硬化および/または乾燥することができる吸水性樹脂含水組成物が得られるということは、本発明によって初めて見い出された知見であるということができる。 That is, the technique described in Patent Document 19 and the present invention are completely different from each other in technical idea. After obtaining the water-absorbing resin water-containing material by mixing the water-absorbing resin particles and the aqueous liquid, further mixing the fine particles. It can be said that the water-absorbing resin water-containing composition having fluidity and capable of being efficiently cured and / or dried is obtained by the present invention for the first time.
<静置、通気>
本発明は、硬化工程および/または乾燥工程が、静置および通気のうち少なくとも一つを伴ってもよい。すなわち、硬化工程および/または乾燥工程を、静置および通気のうち少なくとも一つを伴う条件下で行ってもよい。ここで、上記「静置」とは、上記吸水性樹脂含水組成物を攪拌しない状態または非流動状態におくことをいう。
<Standing, ventilation>
In the present invention, the curing step and / or the drying step may involve at least one of standing and aeration. That is, the curing step and / or the drying step may be performed under conditions involving at least one of standing and aeration. Here, the term “standing still” refers to placing the water-absorbing resin water-containing composition in a state where it is not stirred or in a non-flowing state.
硬化工程および/または乾燥工程が上記静置を伴うことにより、無攪拌、非流動状態で硬化工程および/または乾燥工程が行われるため、吸水性樹脂造粒物の過剰な粒子破壊を防止することができ、得られる吸水性樹脂造粒物の物性低下を抑えることができる。また、静置には特段の装置が必要とされないため、上記効果を伴う硬化工程および/または乾燥工程を低エネルギーで行うことができる。 Since the curing step and / or drying step is accompanied by the above-mentioned standing, the curing step and / or drying step is performed in a non-stirring and non-flowing state, thereby preventing excessive particle destruction of the water-absorbent resin granulated product. It is possible to suppress deterioration of physical properties of the resulting water-absorbent resin granulated product. Moreover, since a special apparatus is not required for stationary, the hardening process and / or drying process which have the said effect can be performed with low energy.
また、本発明は硬化工程および/または乾燥工程が、通気を伴っても良い。通気を伴うことによって、吸水性樹脂組成物から蒸発した水分が系外に移動する。そのため、高効率で硬化工程および/または乾燥工程を行うことができる。通気を行う方法としては、特に限定されるものではない。通気の風量としては、線速0.01m/秒以上10m/秒以下、更に好ましくは0.5m/秒以上3m/秒以下である。 In the present invention, the curing step and / or the drying step may be accompanied by ventilation. By accompanying aeration, water evaporated from the water-absorbent resin composition moves out of the system. Therefore, the curing process and / or the drying process can be performed with high efficiency. The method for venting is not particularly limited. The air flow rate of the ventilation is from 0.01 m / second to 10 m / second, more preferably from 0.5 m / second to 3 m / second.
硬化工程および/または乾燥工程は、静置および通気のうち少なくとも一つを伴っていればよいため、静置と通気とは同時に行われていてもよいし、何れか一方のみが行われていてもよい。 Since the curing step and / or the drying step may involve at least one of standing and aeration, the standing and aeration may be performed at the same time, or only one of them may be performed. Also good.
さらに、これら静置、通気は加熱を伴っても良い。「加熱を伴う」とは、硬化工程および/または乾燥工程において、上述した加熱装置を加熱した状態にすることである。加熱を伴うことで、硬化工程および/または、乾燥工程が加熱状況下で行われ、上記工程の効率をさらに向上させることができる。 Furthermore, these standing and ventilation may be accompanied by heating. “With heating” means that the heating device described above is heated in the curing step and / or the drying step. By accompanying heating, the curing step and / or the drying step are performed under heating conditions, and the efficiency of the above steps can be further improved.
本発明は、硬化および/または乾燥を従来よりも非常に効率化することができるため、熱量の小さい小型乾燥機でも短時間で硬化および/または乾燥を行うことができる。それゆえ、製造時間の短縮、製造コストの削減、省エネルギー等の観点から非常に有用である。例えば、特許文献19に記載の技術では、好ましくは100℃から150℃の範囲の乾燥温度で乾燥させることが開示されているが、後述する本発明の実施例においては、吸水性樹脂含水組成物を密閉容器中で60℃の雰囲気下に1時間静置(無攪拌、非流動状態)することで硬化することに成功している。 According to the present invention, curing and / or drying can be made much more efficient than before, and therefore, curing and / or drying can be performed in a short time even with a small dryer having a small amount of heat. Therefore, it is very useful from the viewpoint of shortening the manufacturing time, reducing the manufacturing cost, and saving energy. For example, in the technique described in Patent Document 19, it is disclosed that drying is preferably performed at a drying temperature in the range of 100 ° C. to 150 ° C. In the examples of the present invention described later, a water-absorbing resin water-containing composition is disclosed. Has been successfully cured by allowing it to stand in an airtight container at 60 ° C. for 1 hour (no stirring, non-flowing state).
上記硬化工程および/または乾燥工程によって、上記吸水性樹脂含水組成物の流動性をさらに高めた、比較的粒径の揃った吸水性樹脂造粒物を得ることができる。本明細書において「吸水性樹脂造粒物」とは、吸水性樹脂含水組成物を硬化および/または乾燥させたものをいう。吸水性樹脂造粒物に対しては、さらに必要に応じて粉砕および分級を行ってもよい。吸水性樹脂造粒物の造粒後の粒子径については特に限定されるものではないが、造粒前後における重量平均粒子径の差は10μm以上1000μm以下であることが好ましく、より好ましくは20μm以上500μm以下、さらに好ましくは30μm以上300μm以下である。 By the curing step and / or the drying step, a water-absorbent resin granulated product having a relatively uniform particle diameter and further improving the fluidity of the water-absorbing resin water-containing composition can be obtained. In the present specification, the “water absorbent resin granulated product” refers to a product obtained by curing and / or drying a water absorbent resin water-containing composition. The water-absorbent resin granulated product may be further pulverized and classified as necessary. The particle diameter after granulation of the water-absorbent resin granulated product is not particularly limited, but the difference in weight average particle diameter before and after granulation is preferably 10 μm or more and 1000 μm or less, more preferably 20 μm or more. It is 500 μm or less, more preferably 30 μm or more and 300 μm or less.
粉砕の方法は特に限定されるものではなく、従来公知の方法を用いることができる。例えば、ローラーミル、ナイフミル、ハンマーミル、ピンミル、ジェットミル等の粉砕機を用いて粉砕する方法を挙げることができる。上記粉砕機は、粉砕機自体の内壁面を加熱する手段を備えていることが好ましい。 The method of pulverization is not particularly limited, and a conventionally known method can be used. For example, the method of grind | pulverizing using grinders, such as a roller mill, a knife mill, a hammer mill, a pin mill, a jet mill, can be mentioned. The pulverizer preferably includes means for heating the inner wall surface of the pulverizer itself.
分級の方法も特に限定されるものではないが、篩分級(金属篩、ステンレス鋼製)によることが好ましい。好ましくは、目的とする物性と粒度のため、分級は複数枚の篩を同時に使用することが好ましい。 Although the classification method is not particularly limited, it is preferable to use a sieve classification (metal sieve, made of stainless steel). Preferably, for the purpose of physical properties and particle size, it is preferable to use a plurality of sieves for classification.
<分割造粒法>
また、他の実施形態において、上記水性液混合工程が、第一の吸水性樹脂粒子と水性液とを混合した系に、さらに、第二の吸水性樹脂粒子を混合することにより吸水性樹脂含水物を得るものであってもよい。以下、当該実施形態に係る製造方法を便宜上「分割造粒法」と称する。分割造粒法では、吸水性樹脂微粒子を分けて添加することで、水性液を必要とする吸水性樹脂粒子に水性液を意図的に不均一に添加することができる。
<Split granulation method>
In another embodiment, the aqueous liquid mixing step further includes mixing the second water-absorbent resin particles in a system in which the first water-absorbent resin particles and the aqueous liquid are mixed, thereby adding water-absorbing resin water content. You may obtain things. Hereinafter, the manufacturing method according to the embodiment is referred to as “divided granulation method” for convenience. In the split granulation method, the aqueous liquid can be intentionally and non-uniformly added to the water-absorbent resin particles that require the aqueous liquid by adding the water-absorbing resin fine particles separately.
上記分割造粒法では、上記第一の吸水性樹脂粒子が、粒子径200μm未満の粒子を主成分とする吸水性樹脂粒子(以下、微粉という)であって、該微粉と水性液とを混合することにより得られた微粉含水物に、さらに粒子径200μm以上850μm未満の粒子を主成分とする第二の吸水性樹脂粒子(以下、粗粒子という)を混合することにより吸水性樹脂含水物を得るものであることが好ましい。「微粉含水物」とは、少なくとも上記微粉と水性液とが混合され含水されたものをいう。 In the split granulation method, the first water-absorbing resin particles are water-absorbing resin particles (hereinafter referred to as fine powder) mainly composed of particles having a particle diameter of less than 200 μm, and the fine powder and the aqueous liquid are mixed. The water-absorbent resin water-containing product is further mixed with the fine water-containing product obtained by mixing the second water-absorbent resin particles (hereinafter referred to as coarse particles) mainly composed of particles having a particle size of 200 μm or more and less than 850 μm. It is preferable to obtain. The “fine powder hydrated product” means a mixture of at least the fine powder and the aqueous liquid.
上記「粒子径200μm未満の吸水性樹脂粒子」とは、標準篩分級で規定される粒子径が200μm未満の吸水性樹脂粒子をいう。換言すれば、目開き200μmのJIS標準篩を通過する吸水性樹脂粒子をいう。 The “water-absorbing resin particles having a particle diameter of less than 200 μm” refers to water-absorbing resin particles having a particle diameter defined by standard sieve classification of less than 200 μm. In other words, it refers to water-absorbent resin particles that pass through a JIS standard sieve having an opening of 200 μm.
係る吸水性樹脂粒子(微粉)には、上述のように、水性液が分布しにくいため、微粉を含有したままの吸水性樹脂粒子においては、造粒されずに残存する微粉の割合が高くなり、粒径の揃った造粒粒子を得ることが困難になる。また、残存する微粉が多いと、粉塵の発生等による作業環境悪化や、吸水性樹脂造粒物の吸水特性低下などの原因ともなりうる。 As described above, the water-absorbing resin particles (fine powder) are difficult to distribute the aqueous liquid, and therefore, in the water-absorbing resin particles containing fine powder, the proportion of fine powder remaining without granulation becomes high. It becomes difficult to obtain granulated particles having a uniform particle size. Moreover, when there are many fine powders remaining, it may become the cause of the working environment deterioration by generation | occurrence | production of dust etc., and the water absorption characteristic fall of a water absorbent resin granulated material.
本発明者は、吸水性樹脂粒子を予め微粉とそれ以外の粒子とに分離し、微粉をまず造粒した後にそれ以外の粒子を混合し、さらに微粒子を混合することにより、微粉を効率的に造粒することができ、微粉残存量の少ない、粒径の揃った造粒粒子を効率よく製造することができることを見い出した。これによって、微粉をも吸水性樹脂造粒物の原料として有効に利用できるので、吸水性樹脂造粒物の収率向上を図ることができる他、粉塵の発生等を減らすことができるので、作業効率を向上させることもできる。また、得られる吸水性樹脂造粒物は微粉の残存率が低いので、吸水特性等の物性が良好なものとなる。 The present inventor separated the water-absorbing resin particles into fine powder and other particles in advance, first granulated the fine powder, then mixed the other particles, and further mixed the fine particles to efficiently remove the fine powder. It has been found that granulated particles having a uniform particle diameter that can be granulated and have a small amount of fine powder can be efficiently produced. As a result, fine powder can be effectively used as a raw material for the water-absorbent resin granulated product, so that the yield of the water-absorbent resin granulated product can be improved and the generation of dust can be reduced. Efficiency can also be improved. Moreover, since the obtained water-absorbent resin granulated product has a low residual ratio of fine powder, physical properties such as water absorption properties are good.
吸水性樹脂粒子から微粉を分離する方法としては、従来公知の方法を用いることができる。例えば、微粉を含む吸水性樹脂粒子を、分級効率を考えて目開き200μmないし、150μmのJIS標準篩を用いて分級する方法を挙げることができる。 As a method for separating fine powder from the water-absorbent resin particles, a conventionally known method can be used. For example, a method of classifying water-absorbent resin particles containing fine powder using a JIS standard sieve having an opening of 200 μm to 150 μm in consideration of the classification efficiency.
上記微粉の重量平均粒子径は200μm未満であることが好ましい。上記微粉は粒子径200μm未満の粒子を主成分とする吸水性樹脂粒子であり、粒子径が150μm以下の吸水性樹脂粉末の割合が好ましくは50重量%以上(上限100重量%)、より好ましくは70重量%以上、さらに好ましくは90重量%以上である。 The weight average particle diameter of the fine powder is preferably less than 200 μm. The fine powder is a water-absorbent resin particle mainly composed of particles having a particle diameter of less than 200 μm, and the proportion of the water-absorbent resin powder having a particle diameter of 150 μm or less is preferably 50% by weight or more (upper limit 100% by weight), more preferably It is 70% by weight or more, more preferably 90% by weight or more.
粗粒子の重量平均粒子径は好ましくは200μm以上800μm以下、より好ましくは230μm以上600μm以下、さらに好ましくは260μm以上500μm以下である。粗粒子は乾燥した状態であることが好ましい。本発明において乾燥した状態とは吸水性樹脂粉末の含水率が必ずしも0%である必要はなく、通常0%以上15%未満、好ましくは0%以上10%以下の範囲であればよい。なお、粗粒子とは、粒子径200μm以上850μm未満の粒子を主成分とする吸水性樹脂粒子のことをいい、標準篩分級で規定される粒子径が200μm以上850μm未満の吸水性樹脂粒子を80%以上(上限100%)、好ましくは90%以上含んでいる吸水性樹脂粒子をいう。 The weight average particle diameter of the coarse particles is preferably 200 μm or more and 800 μm or less, more preferably 230 μm or more and 600 μm or less, and further preferably 260 μm or more and 500 μm or less. The coarse particles are preferably in a dry state. In the present invention, the dry state does not necessarily mean that the water content of the water-absorbent resin powder is 0%, and it may be in the range of usually 0% to less than 15%, preferably 0% to 10%. The coarse particles refer to water-absorbing resin particles mainly composed of particles having a particle size of 200 μm or more and less than 850 μm, and 80 particles of water-absorbing resin particles having a particle size defined by standard sieve classification of 200 μm or more and less than 850 μm. % Or more (upper limit 100%), preferably 90% or more of water-absorbent resin particles.
微粉と粗粒子の割合は特に限定はないが、通常は微粉と粗粒子の割合である微粉/粗粒子の重量比が1/99以上50/50以下、好ましくは2/98以上40/60以下、より好ましくは3/97以上30/70以下の範囲内である。 The ratio of fine powder to coarse particles is not particularly limited, but the weight ratio of fine powder / coarse particles, which is usually the ratio of fine powder to coarse particles, is 1/99 or more and 50/50 or less, preferably 2/98 or more and 40/60 or less. More preferably, it is in the range of 3/97 or more and 30/70 or less.
上記水性液混合工程において、微粉と水性液とを混合する方法としては、既に説明した吸水性樹脂粒子と水性液とを混合する方法と同様の方法を用いることができる。本明細書におけるその他に混合可能な成分としては、「吸水性樹脂含水物」の説明において述べたものと同様のものを用いることができる。 In the aqueous liquid mixing step, as a method of mixing the fine powder and the aqueous liquid, a method similar to the method of mixing the water absorbent resin particles and the aqueous liquid described above can be used. As other components that can be mixed in the present specification, the same components as those described in the description of the “water-absorbing resin water-containing product” can be used.
上記「粗粒子混合工程」は、上記微粉含水物と粒子径200μm以上850μm未満の粒子を主成分とする吸水性樹脂粒子(以下、「粗粒子」ともいう)とを混合することにより粗粒子含水物を得る工程である。該粗粒子は、標準篩分級で規定される粒子径が200μm以上850μm未満の吸水性樹脂粒子を80%以上(上限100%)含んでいることが好ましく、90%以上含んでいることがより好ましい。 The above-mentioned “coarse particle mixing step” is performed by mixing the above-mentioned fine powder hydrate with water-absorbent resin particles (hereinafter, also referred to as “coarse particles”) mainly composed of particles having a particle size of 200 μm or more and less than 850 μm. This is a process for obtaining a product. The coarse particles preferably contain 80% or more (upper limit of 100%) of water-absorbing resin particles having a particle size defined by standard sieve classification of 200 μm or more and less than 850 μm, and more preferably 90% or more. .
上記微粉含水物と上記粗粒子とを混合する方法は特に限定されるものではなく、既に説明した従来公知の混合機を用いて行うことができる。また、上記微粉含水物と上記粗粒子とを混合した吸水性樹脂含水物においては、微粉含水物と粗粒子とは結合していても構わない。他に混合可能な成分としては、例えば、微粒子混合工程で添加する微粒子を分散させるための水性液や、各種有機溶剤等が挙げられる。 The method for mixing the fine hydrated product and the coarse particles is not particularly limited, and can be carried out using a conventionally known mixer already described. In the water-absorbing resin hydrate containing the fine powder hydrate and the coarse particles, the fine powder hydrate and the coarse particles may be combined. Other components that can be mixed include, for example, an aqueous liquid for dispersing fine particles added in the fine particle mixing step, various organic solvents, and the like.
微粒子を吸水性樹脂含水物に添加する方法、混合方法、微粒子の種類、粒子径、量については、<微粒子混合工程>の項で述べたものと同様である。なお、微粒子の量については、分割造粒法においても、吸水性樹脂粒子100重量部に対して0.05重量部以上20重量部以下であることが好ましいが、分割造粒法における「吸水性樹脂粒子100重量部」とは、「微粉と粗粒子とを合わせたもの100重量部」の意味となる。 The method of adding the fine particles to the water-absorbing resin hydrate, the mixing method, the kind of fine particles, the particle diameter, and the amount are the same as those described in the section of <Fine particle mixing step>. In addition, the amount of fine particles is preferably 0.05 parts by weight or more and 20 parts by weight or less with respect to 100 parts by weight of the water-absorbing resin particles also in the split granulation method. The term “100 parts by weight of resin particles” means “100 parts by weight of a combination of fine powder and coarse particles”.
また、硬化工程および/または乾燥工程は、既に説明したものと同様である。 The curing step and / or the drying step are the same as those already described.
上記分割造粒法では、上記水性液の量が、吸水性樹脂粒子100重量部に対して通常1重量部以上150重量部以下、好ましくは5重量部以上100重量部以下、より好ましくは5重量部以上50重量部以下、よりさらに好ましくは5重量部以上30重量部以下、最も好ましくは5重量部以上15重量部以下であることが好ましい。 In the split granulation method, the amount of the aqueous liquid is usually 1 part by weight or more and 150 parts by weight or less, preferably 5 parts by weight or more and 100 parts by weight or less, more preferably 5 parts by weight, with respect to 100 parts by weight of the water absorbent resin particles. It is preferable that they are 5 parts by weight or more and 50 parts by weight or less, more preferably 5 parts by weight or more and 30 parts by weight or less, and most preferably 5 parts by weight or more and 15 parts by weight or less.
上記微粉含水物(含水ゲル状物ともいう)の含水率(後述する実施例に記載の測定方法で規定)は、通常20重量%以上99重量%以下であり、30重量%以上95重量%以下であることが好ましく、より好ましくは40重量%以上90重量%以下である。 The moisture content (specified by the measurement method described in the examples described later) of the finely divided water-containing material (also referred to as a water-containing gel-like material) is usually 20% to 99% by weight, and 30% to 95% by weight. It is preferable that it is 40 wt% or more and 90 wt% or less.
図2は、以上説示した分割造粒法における水性液混合工程、微粒子混合工程の流れを示す模式図である。図2に示すように、水性液混合工程において微粉と水性液とを混合することにより造粒が進行して微粉含水物が得られる。次いで、微粉含水物および/またはその凝集体と粗粒子とを混合することにより吸水性樹脂含水物が得られる。さらに、吸水性樹脂含水物と微粒子とを混合することにより、凝集が解かれ、塊状体が形成されることなく、吸水性樹脂含水組成物が生成される。 FIG. 2 is a schematic diagram showing the flow of the aqueous liquid mixing step and the fine particle mixing step in the split granulation method described above. As shown in FIG. 2, granulation progresses by mixing the fine powder and the aqueous liquid in the aqueous liquid mixing step, and a fine powder hydrate is obtained. Next, the water-absorbent resin hydrate is obtained by mixing the fine powder hydrate and / or the aggregate thereof and the coarse particles. Furthermore, by mixing the water-absorbing resin water-containing material and the fine particles, aggregation is released and a water-absorbing resin water-containing composition is generated without forming a lump.
<本発明に係る製造方法によって得られた吸水性樹脂造粒物の物性>
本発明に係る製造方法によって得られた吸水性樹脂造粒物の生理食塩水の無加圧下吸収倍率(CRC)は27g/g以上、好ましくは30g/g以上、33g/g以上、36g/g以上とされる。無加圧下吸収倍率が20g/g未満である場合にはおむつに使用した場合に高物性を示さないおそれがある。また、上限は特には問わないが、製造上の困難によるコストアップから50g/g程度で十分である。
<Physical properties of the water-absorbent resin granulated product obtained by the production method according to the present invention>
The absorption capacity (CRC) of the water-absorbent resin granulated product obtained by the production method according to the present invention under non-pressurized saline is 27 g / g or more, preferably 30 g / g or more, 33 g / g or more, 36 g / g. It is said above. When the absorption capacity under no pressure is less than 20 g / g, there is a possibility that high physical properties are not exhibited when used for diapers. Moreover, although an upper limit is not ask | required in particular, about 50 g / g is enough from the cost increase by the difficulty on manufacture.
本発明に係る製造方法によって得られた吸水性樹脂造粒物の1.9kPa荷重下での加圧下吸収倍率(AAP1.9kPa)は20g/g以上、より好ましくは22g/g以上、さらに好ましくは24g/g以上、特に好ましくは26g/g以上とされる。加圧下吸収倍率が20g/g未満である場合にはおむつに使用した場合に高物性を示さないおそれがある。また、上限は特には問わないが、製造上の困難によるコストアップから40g/g程度で十分である。 The absorption capacity under load (AAP 1.9 kPa) under a load of 1.9 kPa of the water absorbent resin granulated product obtained by the production method according to the present invention is 20 g / g or more, more preferably 22 g / g or more, and still more preferably. It is 24 g / g or more, particularly preferably 26 g / g or more. If the absorption capacity under pressure is less than 20 g / g, high physical properties may not be exhibited when used for diapers. Moreover, although an upper limit is not ask | required in particular, about 40 g / g is enough from the cost increase by the difficulty on manufacture.
本発明に係る製造方法によって得られた吸水性樹脂造粒物の4.8kPa荷重下での加圧下吸収倍率(AAP4.8kPa)は10g/g以上、より好ましくは15g/g以上、さらに好ましくは20g/g以上とされる。加圧下吸収倍率が10g/g未満である場合にはおむつに使用した場合に高物性を示さないおそれがある。また、上限は特に問わないが、製造上の困難によるコストアップから30g/g程度で十分である。 The absorption capacity under pressure (AAP 4.8 kPa) under a load of 4.8 kPa of the water absorbent resin granulated product obtained by the production method according to the present invention is 10 g / g or more, more preferably 15 g / g or more, and still more preferably. 20 g / g or more. When the absorption capacity under pressure is less than 10 g / g, high physical properties may not be exhibited when used for diapers. Moreover, although an upper limit is not ask | required in particular, about 30 g / g is enough from the cost increase by the difficulty on manufacture.
本発明に係る製造方法によって得られた吸水性樹脂造粒物の重量平均粒子径(D50)は200以上800μm以下、より好ましくは250以上600μm以下、さらに好ましくは300以上500μm以下であり、150μm未満の微粉末の量が非常に少ないことが好ましい。具体的には、プロセスダメージ前で0以上5%以下、さらに3%以下、特に1%以下であることがより好ましく、プロセスダメージ後でも0以上5%以下、さらに3%以下であることが好ましい。対数標準偏差(σζ)は0.25以上0.50以下、好ましくは0.30以上0.45以下に制御される。 The weight average particle diameter (D50) of the water-absorbent resin granulated product obtained by the production method according to the present invention is 200 or more and 800 μm or less, more preferably 250 or more and 600 μm or less, further preferably 300 or more and 500 μm or less, and less than 150 μm. It is preferable that the amount of the fine powder is very small. Specifically, it is preferably 0 or more and 5% or less, more preferably 3% or less, particularly 1% or less before the process damage, and preferably 0 or more and 5% or less, and further 3% or less even after the process damage. . The logarithmic standard deviation (σζ) is controlled to be 0.25 to 0.50, preferably 0.30 to 0.45.
本発明に係る製造方法によって得られた吸水性樹脂造粒物の吸水速度(Vortex)は、20秒以上50秒以下、より好ましくは20秒以上40秒以下、さらに好ましくは20秒以上30秒以下である。 The water absorption rate (Vortex) of the water-absorbent resin granulated product obtained by the production method according to the present invention is 20 seconds to 50 seconds, more preferably 20 seconds to 40 seconds, and further preferably 20 seconds to 30 seconds. It is.
吸水速度が50秒を超える場合は、おむつに使用した場合に、漏れや戻り量の増加を生じるおそれがある。また、吸水速度が20秒よりも速い場合は、おむつに使用した場合に、吸水速度が速いことによって、おむつの吸収体中においてゲルブロックが生じ、漏れを引き起こすおそれがある。 When the water absorption speed exceeds 50 seconds, there is a possibility that leakage or an increase in the amount of return will occur when used for diapers. Moreover, when a water absorption speed is faster than 20 seconds, when it uses for a diaper, a gel block may arise in the absorber of a diaper by a high water absorption speed, and there exists a possibility of causing a leak.
本発明に係る製造方法によって得られた吸水性樹脂造粒物の水分含量(含水率)は、吸水性樹脂粒子に対して1重量%以上150重量%以下、好ましくは5重量%以上100重量%以下、より好ましくは、5重量%以上50重量%以下、さらに好ましくは、5重量%以上30重量%以下、よりさらに好ましくは、5重量%以上20重量%以下、特に好ましくは5重量%以上15重量%以下である。水分含量(含水率)が1重量%未満である場合、造粒が不十分であるため、微粉を再生しやすくなり、おむつ等の最終製品とした場合、目詰まりを起こしやすく、漏れなどの原因となるおそれがあり好ましくない。 The water content (water content) of the water-absorbent resin granulated product obtained by the production method according to the present invention is 1% by weight or more and 150% by weight or less, preferably 5% by weight or more and 100% by weight with respect to the water-absorbent resin particles. Or less, more preferably 5% by weight or more and 50% by weight or less, further preferably 5% by weight or more and 30% by weight or less, still more preferably 5% by weight or more and 20% by weight or less, and particularly preferably 5% by weight or more and 15% by weight or less. % By weight or less. If the water content (moisture content) is less than 1% by weight, granulation is inadequate, which makes it easier to regenerate fine powder. When the final product such as diapers is used, clogging is likely to occur and causes leakage, etc. This is not preferable.
一方、水分含量(含水率)が150重量%よりも多い場合、過剰な造粒強度によって塊状化しやすくなり、これを整粒(粉砕)する際に、吸水性樹脂粒子にダメージがかかることで、吸収倍率等の諸物性が低下し、おむつ等の最終製品とした場合、漏れなどの原因となるおそれがあり好ましくない。 On the other hand, when the water content (water content) is more than 150% by weight, it becomes easy to agglomerate due to excessive granulation strength, and when this is sized (pulverized), the water absorbent resin particles are damaged, Various physical properties such as absorptivity are reduced, and if it is a final product such as a diaper, it may cause a leakage or the like, which is not preferable.
本発明に係る製造方法によって得られた吸水性樹脂造粒物の微粒子含有量(無機微粒子含有量)は吸水性樹脂粒子に対して0.01重量%以上20重量%以下、好ましくは、0.01重量%以上15重量%以下、より好ましくは、0.1重量%以上10重量%以下の含有量である。微粒子含有量が0.01重量%未満だと、十分な流動性を得ることができないおそれがある。上記微粒子含有量が、0.01重量%以上10重量%以下であれば、十分な流動性を得ることができる。20重量%を越えると、吸水性樹脂としての性能(後述する加圧下吸収倍率等)を低下させるおそれがあり、好ましくない。 The fine particle content (inorganic fine particle content) of the water-absorbent resin granulated product obtained by the production method according to the present invention is 0.01% by weight or more and 20% by weight or less with respect to the water-absorbent resin particles, preferably 0.8%. The content is from 01% by weight to 15% by weight, and more preferably from 0.1% by weight to 10% by weight. When the fine particle content is less than 0.01% by weight, there is a possibility that sufficient fluidity cannot be obtained. When the content of the fine particles is 0.01% by weight or more and 10% by weight or less, sufficient fluidity can be obtained. If it exceeds 20% by weight, the performance as a water-absorbent resin (such as absorption capacity under pressure described later) may be lowered, which is not preferable.
本発明に係る製造方法によって得られた吸水性樹脂造粒物は、吸水性樹脂造粒物100重量部に対し、目開き150μmのJIS標準篩を通過する粒子が0重量部以上5重量部以下であることが好ましい。これにより、吸水性樹脂造粒物をおむつなどに使用した場合、微粉による目詰まりを起こし難くなる。そのため、おむつ等の製品における通液性の低下を抑えることができる。 The water-absorbent resin granulated product obtained by the production method according to the present invention has 0 to 5 parts by weight of particles passing through a JIS standard sieve having an aperture of 150 μm with respect to 100 parts by weight of the water-absorbent resin granulated product. It is preferable that Thereby, when the water-absorbent resin granulated product is used for a diaper or the like, clogging due to fine powder is less likely to occur. Therefore, the fall of the liquid permeability in products, such as a diaper, can be suppressed.
このように、本発明に係る製造方法によって得られた吸水性樹脂造粒物において、目開き150μmのJIS標準篩を通過する粒子は、その重量部が低い方が好ましいため、含有量は0重量部でも構わない。 Thus, in the water-absorbent resin granulated product obtained by the production method according to the present invention, the particle passing through the JIS standard sieve having an opening of 150 μm is preferably lower in weight part, so the content is 0 wt. It doesn't matter if it's part.
本発明に係る吸水性樹脂造粒物は、水分を吸水性樹脂造粒物の全量100重量部に対して5重量部以上15重量部以下、無機微粒子を吸水性樹脂造粒物の全量100重量部に対して0.01重量部以上10重量部以下含み、(1)0.90重量%の塩化ナトリウム水溶液に対する無加圧下吸収倍率が27g/g以上であり、(2)0.90重量%の塩化ナトリウム水溶液に対する1.9kPaでの加圧下吸収倍率が20g/g以上であり、(3)0.90重量%の塩化ナトリウム水溶液に対する4.8kPaでの加圧下吸収倍率が10g/g以上であり、(4)0.90重量%の塩化ナトリウム水溶液に対する吸収速度が20秒以上50秒以下であり、(5)吸水性樹脂造粒物100重量部に対し、目開き150μmのJIS標準篩を通過する粒子が0重量部以上5重量部以下であるという物性を有する。 The water-absorbent resin granulated product according to the present invention has a water content of 5 to 15 parts by weight with respect to 100 parts by weight of the total amount of the water-absorbent resin granulated product, and inorganic fine particles of 100% by weight of the water-absorbent resin granulated product. 0.01 part by weight or more and 10 parts by weight or less with respect to part, (1) Absorption capacity under no pressure with respect to 0.90% by weight sodium chloride aqueous solution is 27g / g or more, (2) 0.90% by weight The absorption capacity under pressure at 1.9 kPa with respect to an aqueous sodium chloride solution is 20 g / g or more, and (3) the absorption capacity under pressure at 4.8 kPa with respect to a 0.90 wt% aqueous sodium chloride solution is 10 g / g or more. (4) Absorption rate with respect to 0.90% by weight sodium chloride aqueous solution is 20 seconds or more and 50 seconds or less, and (5) JIS standard sieve having an opening of 150 μm with respect to 100 parts by weight of the water-absorbent resin granulated product. Pass Having physical properties that the particles are less than 5 parts by weight or more 0 parts by weight.
係る吸水性樹脂造粒物は、既に説明した本発明に係る吸水性樹脂造粒物の製造方法によって製造することができる。すなわち、製造方法としては、一括造粒法であっても、分割造粒法であってもよい。上記(1)〜(5)に記載した物性については上述のとおりである。 Such a water-absorbent resin granulated product can be produced by the method for producing a water-absorbent resin granulated product according to the present invention described above. That is, the production method may be a batch granulation method or a split granulation method. The physical properties described in the above (1) to (5) are as described above.
なお、分割造粒法で上記本発明に係る吸水性樹脂造粒物を製造する場合、第一の吸水性樹脂粒子と第二の吸水性樹脂粒子の合計100重量部に対して水性液を5重量部以上20重量部以下使用する。また、上記本発明に係る吸水性樹脂造粒物を製造する場合、吸水性樹脂造粒物に対して含まれる水分量および無機微粒子量は、吸水性樹脂粒子に対して含まれる水分量および無機微粒子含有量になるように、水性液添加量および無機微粒子添加量を適宜調整することが好ましい。 When the water-absorbent resin granulated product according to the present invention is produced by the split granulation method, the aqueous liquid is added to 100 parts by weight of the total of the first water-absorbent resin particles and the second water-absorbent resin particles. More than 20 parts by weight is used. When the water absorbent resin granulated product according to the present invention is produced, the amount of water and inorganic fine particles contained in the water absorbent resin granulated product are the amount of water contained in the water absorbent resin particles and the amount of inorganic fine particles. It is preferable to appropriately adjust the addition amount of the aqueous liquid and the addition amount of the inorganic fine particles so as to obtain the fine particle content.
<本発明に係る製造方法によって製造された吸水性樹脂造粒物の用途>
本発明に係る製造方法によって製造された吸水性樹脂造粒物には、消毒剤、抗菌剤、香料、発泡剤、顔料、染料、親水性短繊維、肥料、酸化剤、還元剤、水、塩類等を0重量%以上30重量%以下、好ましくは0重量%以上5重量%以下の範囲で添加し、これにより、種々の機能を付与させることもできる。本発明に係る製造方法によって製造された吸水性樹脂造粒物は従来公知の各種吸水性樹脂の用途に適用できるが、微粉末が少なく、加圧下の吸収特性や吸収速度に優れているため、これらの性能を重視される紙おむつや生理用ナプキン、失禁パット等の吸収体を含む衛生材料や廃液固化剤、止水剤等の吸水性物品に好適に使用できる。
<Use of water-absorbent resin granulated product produced by the production method according to the present invention>
The water absorbent resin granulated product produced by the production method according to the present invention includes disinfectant, antibacterial agent, fragrance, foaming agent, pigment, dye, hydrophilic short fiber, fertilizer, oxidizing agent, reducing agent, water, and salts. Etc. may be added in the range of 0 wt% to 30 wt%, preferably 0 wt% to 5 wt%, thereby imparting various functions. The water-absorbent resin granulated product produced by the production method according to the present invention can be applied to the use of various conventionally known water-absorbent resins, but it has few fine powders and is excellent in absorption characteristics and absorption speed under pressure. It can be suitably used for hygienic materials including absorbent materials such as disposable diapers, sanitary napkins, and incontinence pads, and water-absorbing articles such as waste liquid solidifying agents and water-stopping agents.
なお、本発明は以上説示した各構成に限定されるものではなく、特許請求の範囲に示した範囲内で種々の変更が可能であり、異なる実施形態にそれぞれ開示された技術的手段を適宜組み合わせて得られる実施形態についても本発明の技術的範囲に含まれる。
また、本発明には以下の形態が含まれる。本発明の吸水性樹脂造粒物の製造方法は、第一の吸水性樹脂粒子の重量平均粒子径が第二の吸水性樹脂粒子の重量平均粒子径よりも小さいことが好ましい。
また、本発明に係る吸水性樹脂造粒物の製造方法では、上記工程(b)が、吸水性樹脂含水物と微粒子とを混合することにより吸水性樹脂含水組成物を得る微粒子混合工程であり、上記吸水性樹脂含水組成物を硬化する硬化工程および/または上記吸水性樹脂含水組成物を乾燥する乾燥工程と、を備えることが好ましい。
上記の構成によれば、吸水性樹脂粒子と水性液とを混合することにより、接着力が生じ、造粒が行なわれ、吸水性樹脂含水物が得られる。さらに微粒子を混合することにより、吸水性樹脂含水物同士が接着している面に微粒子が介在することによって、吸水性樹脂含水物同士の接着が剥がされ、微粒子を介した点接着となると考えられる。
これにより、過剰に成長した吸水性樹脂含水物の凝集が解かれ、比較的粒径の揃った造粒粒子(吸水性樹脂含水組成物)に変化するので、短時間で吸水性樹脂含水物に流動性を与えることができる。また、吸水性樹脂含水物の凝集が解かれることで粒子体積あたりの表面積が増加し、造粒粒子間の空隙が増加するため、より低温・短時間で硬化および/または乾燥を行うことができる。したがって、非常に効率的に吸水性樹脂造粒物を製造することができる。
また、本発明に係る吸水性樹脂造粒物の製造方法は、上記水性液混合工程が、第一の吸水性樹脂粒子と水性液とを混合した系に、さらに、第二の吸水性樹脂粒子を混合することにより吸水性樹脂含水物を得るものであることが好ましい。
上記構成によれば、吸水性樹脂微粒子を分けて添加することで、水性液を必要とする吸水性樹脂粒子に水性液を意図的に不均一に添加することができる。
本発明にかかる吸水性樹脂造粒物の製造方法は、工程(a)において、上記水溶液の量が、第一の吸水性樹脂粒子100重量部に対して1重量部以上150重量部以下であることが好ましい。
上記構成によれば、水性液の添加量が、第一の吸水性樹脂粒子に対し、強力な接着力を供することができる量となる。したがって、水性液混合工程において造粒を円滑に進行させることができる。
本発明に係る吸水性樹脂造粒物の製造方法は、上記第一の吸水性樹脂粒子が、粒子径200μm未満の粒子を主成分とする吸水性樹脂粒子(以下、微粉という)であって、該微粉と水性液とを混合することにより得られた微粉含水物に、さらに粒子径200μm以上850μm未満の粒子を主成分とする第二の吸水性樹脂粒子(以下、粗粒子という)を混合することにより吸水性樹脂含水物を得るものであることが好ましい。
吸水性樹脂粒子は、種々の粒径を持つ吸水性樹脂粒子の集合体であり、それぞれの粒子への水性液の分布のされやすさは粒径にある程度依存することが知られている。そのため、当該吸水性樹脂粒子と水性液とを混合した場合、表面架橋された微粉には、粒径が大きい粒子が共存することにより、微粉が造粒するのに十分な造粒強度を得る為の水性液が分配しないおそれがある。したがって造粒されずに残存する微粉の割合が高くなり、粒径の揃った造粒粒子を得ることが困難になる。また、残存する微粉が多いと、粉塵の発生等による作業環境悪化や、吸水性樹脂造粒物の吸水特性低下などの原因ともなりうる。
上記構成によれば、吸水性樹脂粒子を予め粒子径200μm未満の微粉とそれ以外の粒子とに分離し、微粉をまず造粒した後にそれ以外の粒子を混合し、さらに微粒子を混合するので、微粉を効率的に造粒することができる。したがって、微粉残存量の少ない、粒径の揃った造粒粒子を効率よく製造することができる。
また、本発明に係る吸水性造粒物の製造方法では、上記吸水性樹脂粒子が表面架橋処理されていることが好ましい。
表面架橋処理を行うことによって、通液性等、吸水性樹脂粒子の諸特性をより好ましいものとすることができる。したがって、特性の優れた吸水性樹脂造粒物を得ることができる。
また、本発明に係る吸水性樹脂造粒物の製造方法は、上記微粒子の量が、吸水性樹脂粒子100重量部に対して0.01重量部以上10重量部以下であることが好ましい。上記構成によれば、微粒子の量が吸水性樹脂含水物の粒子面の接着を、微粒子が介在した点接着に変化させるために好適な量となるため、吸水性樹脂含水物の塊状化を防ぐことができる。したがって、比較的粒径の揃った吸水性樹脂造粒物を効率的に得ることができる。
また、本発明に係る吸水性樹脂造粒物の製造方法では、上記微粒子が水不溶性無機微粒子であることが好ましい。
上記構成によれば、少量の添加量で吸水性樹脂含水物の凝集を解くことができる。したがって、比較的粒径の揃った造粒粒子を得ることが容易になる。
本発明に係る吸水性樹脂造粒物の製造方法では、上記硬化工程および/または乾燥工程において、吸水性樹脂含水組成物を保温または加熱する温度の範囲が30℃以上250℃以下であることが好ましい。
上記温度範囲が30℃以上250℃以下であることにより、硬化および/または乾燥を従来よりも非常に効率化することができるため、熱量の小さい小型乾燥機でも短時間で加熱を行うことができる。それゆえ、製造時間の短縮、製造コストの削減、省エネルギー等の観点から非常に有用である。
本発明に係る吸水性樹脂造粒物の製造方法では、上記硬化工程および/または乾燥工程が、静置および通気のうち少なくともいずれか一つを伴う工程を備えることが好ましい。
上記硬化工程および/または乾燥工程が、静置(無攪拌、非流動状態)を伴う工程である場合、無攪拌、非流動状態で硬化工程および/または乾燥工程が行われるため、硬化工程および/または乾燥工程において造粒物の破壊が最も生じ難い。したがって、得られる吸水性樹脂造粒物の物性低下を抑えることができる。さらに、低エネルギーコストで静置を伴う工程を行うことが可能である。
また、上記硬化工程および/または乾燥工程が通気を伴う工程を備えることで、蒸発した水分が通気により系外に移動するため、高効率で硬化工程および/または乾燥工程を行うことができる。
また、本発明に係る吸水性樹脂造粒物は、上記無機微粒子が水不溶性無機微粒子であることが好ましい。
上記構成によれば、少量の添加量で吸水性樹脂含水物の凝集を解くことができるため、比較的粒径の揃った吸水性樹脂造粒物を製造することができる。
Note that the present invention is not limited to the configurations described above, and various modifications are possible within the scope of the claims, and technical means disclosed in different embodiments are appropriately combined. Embodiments obtained in this manner are also included in the technical scope of the present invention.
The present invention includes the following forms. In the method for producing a water absorbent resin granulated product of the present invention, it is preferable that the weight average particle diameter of the first water absorbent resin particles is smaller than the weight average particle diameter of the second water absorbent resin particles.
Further, in the method for producing a water absorbent resin granulated product according to the present invention, the step (b) is a fine particle mixing step of obtaining a water absorbent resin hydrous composition by mixing the water absorbent resin hydrous material and the fine particles. It is preferable to include a curing step for curing the water-absorbing resin water-containing composition and / or a drying step for drying the water-absorbing resin water-containing composition.
According to said structure, by mixing a water absorbing resin particle and an aqueous liquid, adhesive force arises and granulation is performed and a water absorbing resin hydrate is obtained. Further, by mixing the fine particles, the fine particles intervene on the surface where the water-absorbing resin hydrates are bonded to each other, so that the adhesion between the water-absorbing resin hydrates is peeled off, and it is considered that the point bonding through the fine particles results. .
As a result, the excessively grown water-absorbing resin hydrous material is deagglomerated and changed to granulated particles having a relatively uniform particle size (water-absorbing resin water-containing composition). It can give fluidity. In addition, since the water-absorbent resin hydrous material is deagglomerated, the surface area per particle volume increases and the gaps between the granulated particles increase, so that curing and / or drying can be performed at a lower temperature and in a shorter time. . Therefore, the water-absorbent resin granulated product can be produced very efficiently.
The method for producing a water-absorbent resin granulated product according to the present invention includes a second water-absorbent resin particle in a system in which the aqueous liquid mixing step is performed by mixing the first water-absorbent resin particles and the aqueous liquid. It is preferable that a water-absorbing resin hydrate is obtained by mixing.
According to the above configuration, by adding the water-absorbing resin fine particles separately, the aqueous liquid can be intentionally added non-uniformly to the water-absorbing resin particles that require the aqueous liquid.
In the method for producing a water absorbent resin granule according to the present invention, in the step (a), the amount of the aqueous solution is 1 part by weight or more and 150 parts by weight or less with respect to 100 parts by weight of the first water absorbent resin particles. It is preferable.
According to the said structure, the addition amount of aqueous liquid turns into an quantity which can provide strong adhesive force with respect to 1st water absorbing resin particle. Therefore, granulation can be smoothly advanced in the aqueous liquid mixing step.
In the method for producing a water-absorbent resin granulated product according to the present invention, the first water-absorbent resin particles are water-absorbent resin particles (hereinafter referred to as fine powder) mainly composed of particles having a particle diameter of less than 200 μm, Second water-absorbent resin particles (hereinafter referred to as coarse particles) mainly composed of particles having a particle diameter of 200 μm or more and less than 850 μm are further mixed with the finely powdered hydrate obtained by mixing the fine powder and the aqueous liquid. Thus, it is preferable to obtain a water-absorbing resin hydrate.
The water-absorbent resin particles are aggregates of water-absorbent resin particles having various particle diameters, and it is known that the ease of distribution of the aqueous liquid to each particle depends to some extent on the particle diameter. Therefore, when the water-absorbing resin particles and the aqueous liquid are mixed, the surface-crosslinked fine powder has a large particle size so that sufficient granulation strength can be obtained for the fine powder to be granulated. The aqueous liquid may not be distributed. Therefore, the proportion of fine powder remaining without granulation becomes high, and it becomes difficult to obtain granulated particles having a uniform particle size. Moreover, when there are many fine powders remaining, it may become the cause of the working environment deterioration by generation | occurrence | production of dust etc., and the water absorption characteristic fall of a water absorbent resin granulated material.
According to the above configuration, the water-absorbent resin particles are separated in advance into fine powder having a particle diameter of less than 200 μm and other particles, the fine powder is first granulated, and then the other particles are mixed, and further the fine particles are mixed. Fine powder can be efficiently granulated. Therefore, it is possible to efficiently produce granulated particles having a small particle size and a uniform particle size.
In the method for producing a water-absorbent granulated product according to the present invention, the water-absorbent resin particles are preferably subjected to surface cross-linking treatment.
By performing the surface cross-linking treatment, various characteristics of the water-absorbent resin particles such as liquid permeability can be made more preferable. Therefore, a water-absorbent resin granulated product having excellent characteristics can be obtained.
In the method for producing a water absorbent resin granulated product according to the present invention, the amount of the fine particles is preferably 0.01 parts by weight or more and 10 parts by weight or less with respect to 100 parts by weight of the water absorbent resin particles. According to the above configuration, since the amount of fine particles is a suitable amount for changing the adhesion of the particle surface of the water-absorbent resin water-containing material to the point adhesion involving the fine particles, the water-absorbent resin water-containing material is prevented from being agglomerated. be able to. Therefore, it is possible to efficiently obtain a water absorbent resin granulated product having a relatively uniform particle size.
In the method for producing a water-absorbent resin granulated product according to the present invention, the fine particles are preferably water-insoluble inorganic fine particles.
According to the said structure, aggregation of a water-absorbing-resin water content can be solved with a small addition amount. Therefore, it becomes easy to obtain granulated particles having a relatively uniform particle size.
In the method for producing a water-absorbent resin granulated product according to the present invention, the temperature range for retaining or heating the water-absorbent resin water-containing composition in the curing step and / or drying step may be 30 ° C. or more and 250 ° C. or less. preferable.
When the above temperature range is 30 ° C. or more and 250 ° C. or less, curing and / or drying can be made more efficient than conventional methods, so that even a small dryer with a small amount of heat can be heated in a short time. . Therefore, it is very useful from the viewpoint of shortening the manufacturing time, reducing the manufacturing cost, and saving energy.
In the method for producing a water absorbent resin granulated product according to the present invention, it is preferable that the curing step and / or the drying step include a step involving at least one of standing and aeration.
In the case where the curing step and / or the drying step is a step accompanied by standing (no stirring, non-flowing state), the curing step and / or the drying step are performed without stirring and non-flowing state. Or destruction of a granulated material hardly occurs in a drying process. Therefore, the physical property fall of the water absorbent resin granulation obtained can be suppressed. Furthermore, it is possible to perform a process that involves standing at a low energy cost.
Moreover, since the said hardening process and / or a drying process are equipped with the process accompanied by ventilation | gas_flowing, the evaporated water | moisture content moves outside the system by ventilation | gas_flowing, Therefore A hardening process and / or a drying process can be performed with high efficiency.
In the water-absorbent resin granulated product according to the present invention, the inorganic fine particles are preferably water-insoluble inorganic fine particles.
According to the above configuration, the water-absorbent resin hydrated product can be flocculated with a small addition amount, so that a water-absorbent resin granulated product having a relatively uniform particle diameter can be produced.
〔実施例〕
以下に、実施例によって本発明をより具体的に説明するが、本発明はこれらに限定されるものではない。なお、本明細書においては、「質量」および「質量%」は、それぞれ「重量」および「重量%」または、「重量部」と同義語として扱う。また、便宜上、「質量部」を単に「部」と、「リットル」を単に「L」と記すことがある。また、「質量%」を「wt%」と記すことがある。
〔Example〕
Hereinafter, the present invention will be described more specifically by way of examples. However, the present invention is not limited to these examples. In the present specification, “mass” and “mass%” are treated as synonymous with “weight” and “weight%” or “part by weight”, respectively. In addition, for convenience, “mass part” may be simply referred to as “part”, and “liter” may be simply referred to as “L”. In addition, “mass%” may be described as “wt%”.
吸水性樹脂粒子、吸水性樹脂含水組成物、吸水性樹脂造粒物等(以下適宜「試料」と称する)の諸性能は以下の方法で測定した。特に記載がない限り下記の測定は25℃±2℃、湿度50RH%の条件下で行われたものとする。 Various performances of the water-absorbent resin particles, the water-absorbent resin-containing composition, the water-absorbent resin granulated product and the like (hereinafter referred to as “sample” as appropriate) were measured by the following methods. Unless otherwise specified, the following measurements are performed under conditions of 25 ° C. ± 2 ° C. and humidity of 50 RH%.
〔試験方法〕
(1)重量平均粒子径(D50)および微粉末割合(150μm通過割合)
吸水性樹脂ないし粒子状吸水剤を、850μm、710μm、600μm、500μm、425μm、300μm、212μm、150μm、106μm、75μm、45μmなどのJIS標準篩で篩い分けし、残留百分率を対数確率紙にプロットした。これにより、重量平均粒子径(D50)および微粉末割合(150μm通過割合)を読み取った。
〔Test method〕
(1) Weight average particle diameter (D50) and fine powder ratio (150 μm passage ratio)
The water-absorbing resin or particulate water-absorbing agent was sieved with a JIS standard sieve such as 850 μm, 710 μm, 600 μm, 500 μm, 425 μm, 300 μm, 212 μm, 150 μm, 106 μm, 75 μm, 45 μm, and the residual percentage was plotted on logarithmic probability paper. . Thereby, the weight average particle diameter (D50) and fine powder ratio (150 μm passage ratio) were read.
篩い分けは吸水性樹脂ないし粒子状吸水剤の10.00gを、上記JIS標準篩(The IIDA TESTING SIEVE:内径80mm)に仕込み、ロータップ型ふるい振盪機((株)飯田製作所製、ES−65型ふるい振盪機)により5分間分級した。なお、重量平均粒子径(D50)とは、米国特許5051259号公報などにあるように一定目開きの標準ふるいで粒子全体の50重量%に対応する標準ふるいの粒子径のことである。 In the sieving, 10.00 g of a water-absorbing resin or a particulate water-absorbing agent is charged into the JIS standard sieve (The IIDA TESTING SIEVE: inner diameter 80 mm), and a low-tap type sieve shaker (manufactured by Iida Seisakusho, ES-65 type). Classification for 5 minutes using a sieve shaker). The weight average particle diameter (D50) is a particle diameter of a standard sieve corresponding to 50% by weight of the whole particle with a standard sieve having a constant mesh as described in US Pat. No. 5,051,259.
またこのとき測定した目開き150μmのJIS標準篩を通過した吸水性樹脂ないし粒子状吸水剤の合計重量から、次式に従って、微粉末割合(重量%)を算出した。 Further, the fine powder ratio (% by weight) was calculated from the total weight of the water-absorbing resin or particulate water-absorbing agent that passed through a JIS standard sieve having an opening of 150 μm, according to the following formula.
微粉末割合(重量%)=(目開き150μmのJIS標準篩を通過した吸水性樹脂(または粒子状吸水剤)の合計重量(g)/吸水性樹脂(または粒子状吸水剤)全体の重量(g))×100
(2)0.90重量%塩化ナトリウム水溶液(生理食塩水)に対する無加圧下吸収倍率(CRC/Centrifuge Retention Capacity)
吸水性樹脂(または粒子状吸水剤)0.20gを不織布製の袋(60mm×85mm)に均一に入れ、25±2℃に調温した0.90重量%塩化ナトリウム水溶液(生理食塩水)中に浸漬した。30分後に袋を引き上げ、遠心分離機を用いて250Gにて3分間水切りを行った後、袋の重量W1(g)を測定した。同様の操作を吸水性樹脂(または粒子状吸水剤)を用いないで行い、その時の重量W0 (g)を測定した。W1およびW0 から、次式に従って、無加圧下吸収倍率(g/g)を算出した。
Fine powder ratio (% by weight) = (total weight (g) of water-absorbing resin (or particulate water-absorbing agent) passed through JIS standard sieve having 150 μm openings / total weight of water-absorbing resin (or particulate water-absorbing agent) ( g)) x 100
(2) Absorption capacity without pressure (CRC / Centrifuge Retention Capacity) with respect to 0.90% by weight sodium chloride aqueous solution (saline)
In a 0.90 wt% aqueous sodium chloride solution (physiological saline), 0.20 g of a water-absorbing resin (or particulate water-absorbing agent) is uniformly placed in a non-woven bag (60 mm x 85 mm) and the temperature is adjusted to 25 ± 2 ° C. Soaked in. After 30 minutes, the bag was pulled up, drained at 250 G for 3 minutes using a centrifuge, and the weight W 1 (g) of the bag was measured. The same operation was performed without using the water-absorbent resin (or particulate water-absorbing agent), and the weight W 0 (g) at that time was measured. From W 1 and W 0 , the absorption capacity without pressure (g / g) was calculated according to the following formula.
0.90重量%塩化ナトリウム水溶液(生理食塩水)に対する無加圧下吸収倍率(g/g)={(重量W1 (g)−重量W0 (g))/吸水性樹脂(または粒子状吸水剤)の重量(g)}−1
(3)含水率
吸水性樹脂(または粒子状吸水剤、または含水ゲル状物)において、水分が占める割合を表す。固形分との関係は、以下の様になる。
Absorption capacity without load (g / g) with respect to 0.90 wt% sodium chloride aqueous solution (physiological saline) = {(weight W 1 (g) −weight W 0 (g)) / water absorbent resin (or particulate water absorption) Weight) (g)}-1
(3) Moisture content In the water-absorbent resin (or particulate water-absorbing agent or hydrated gel-like product), it represents the proportion of moisture. The relationship with the solid content is as follows.
含水率(重量%)=100−固形分(重量%)
含水率の測定方法は、以下の様に行った。
Moisture content (% by weight) = 100-solid content (% by weight)
The method for measuring the moisture content was as follows.
底面の直径が約5cmのアルミカップ(重量W0)に、1gの吸水性樹脂(または粒子状吸水剤、または含水ゲル状物)ないしその含水物を量り取り(重量W1 )、180℃の無風乾燥機中において3時間(含水ゲル状物を測定する場合は16時間)静置し、乾燥させる。乾燥後のアルミカップ+吸水性樹脂(または粒子状吸水物、または含水ゲル状物)の重量(W2)を測定し、以下の式より、含水率を求めた。 Weigh 1 g of water-absorbing resin (or particulate water-absorbing agent or water-containing gel) or water-containing material (weight W 1 ) into an aluminum cup (weight W 0 ) having a bottom diameter of about 5 cm. Allow to stand for 3 hours in a non-air dryer (16 hours when measuring a hydrogel) and dry. The weight (W 2 ) of the dried aluminum cup + water-absorbent resin (or particulate water-absorbing material or water-containing gel-like material) was measured, and the water content was determined from the following equation.
含水率(重量%)={1−(W2−W0 )/W1 }×100
(4)含水率補正した無加圧下吸収倍率
含水率補正した無加圧下吸収倍率は、吸水性樹脂(または粒子状吸水剤)の含水率が0重量%と想定した場合の無加圧下吸収倍率であり、次式に従って算出した。
Water content (% by weight) = {1− (W 2 −W 0 ) / W 1 } × 100
(4) Absorption capacity under no pressure corrected for water content Absorption capacity under no pressure applied after water content correction is the absorption capacity under no pressure when the water content of the water absorbent resin (or particulate water absorbent) is assumed to be 0% by weight. And calculated according to the following equation.
含水率補正した無加圧下吸収倍率(g/g)=(無加圧下吸収倍率(g/g)+含水率(重量%)/100)/(1−含水率(重量%)/100)
(5)0.90重量%塩化ナトリウム水溶液(生理食塩水)に対する1.9kPaでの加圧下吸収倍率(AAP)
目開き38μmのステンレス製金網を円筒断面の一辺(底)に溶着させた内径60mmのプラスチック製支持円筒の底の金網上に、吸水性樹脂(または粒子状吸水剤)0.90gを均一に散布し、その上に外径が60mmよりわずかに小さく支持円筒との壁面に隙間が生じずかつ上下の動きは妨げられないピストン(cover plate)を載置し、支持円筒と吸水性樹脂(または粒子状吸水剤)とピストンの重量W3(g)を測定した。このピストン上に、吸水性樹脂(または粒子状吸水剤)に対して、ピストンを含め1.9kPaの荷重を均一に加えることができるように調整された荷重を載置し、測定装置一式を完成させた。直径150mmのペトリ皿の内側に直径90mm、厚さ5mmのガラスフィルターを置き、25±2℃に調温した0.90重量%塩化ナトリウム水溶液(生理食塩水)をガラスフィルターの上部面と同レベルになるように加えた。その上に直径9cmの濾紙(トーヨー濾紙(株)製、No.2)を1枚載せて表面が全て濡れるようにし、かつ過剰の液を除いた。
Absorption capacity without pressure (g / g) after correction of water content = (absorption capacity without pressure (g / g) + water content (% by weight) / 100) / (1−water content (% by weight) / 100)
(5) Absorption capacity under load (AAP) at 1.9 kPa with respect to 0.90 wt% sodium chloride aqueous solution (saline)
0.90 g of water-absorbing resin (or particulate water-absorbing agent) is evenly sprayed on the metal mesh at the bottom of a plastic support cylinder with an inner diameter of 60 mm in which a stainless steel mesh with a mesh opening of 38 μm is welded to one side (bottom) of the cylinder cross section. Further, a piston (cover plate) whose outer diameter is slightly smaller than 60 mm and no gap is formed on the wall surface with the support cylinder and the vertical movement is not hindered is placed on the support cylinder and the water absorbent resin (or particles). And the weight W 3 (g) of the piston were measured. On this piston, a load adjusted so that a 1.9 kPa load including the piston can be uniformly applied to the water-absorbing resin (or particulate water-absorbing agent) is placed, and a complete measuring device is completed. I let you. Place a glass filter with a diameter of 90 mm and a thickness of 5 mm inside a Petri dish with a diameter of 150 mm, and 0.90 wt% sodium chloride aqueous solution (saline) adjusted to 25 ± 2 ° C at the same level as the upper surface of the glass filter It was added to become. On top of that, a sheet of 9 cm diameter filter paper (Toyo Filter Paper Co., Ltd., No. 2) was placed so that the entire surface was wetted, and excess liquid was removed.
上記測定装置一式を上記湿った濾紙上にのせ、液を荷重下で吸収させた。液面がガラスフィルターの上部から低下したら液を追加し、液面レベルを一定に保った。60分後に測定装置一式を持ち上げ、荷重を取り除いた重量W4(g)(支持円筒と膨潤した吸水性樹脂(または粒子状吸水剤)とピストンの重量)を再測定した。そして、これら重量W3 、W4から、次式に従って、0.90重量%塩化ナトリウム水溶液(生理食塩水)に対する1.9kPaでの加圧下吸収倍率(g/g)を算出した。 The set of measuring devices was placed on the wet filter paper, and the liquid was absorbed under load. When the liquid level dropped from the top of the glass filter, the liquid was added to keep the liquid level constant. After 60 minutes, the set of measuring devices was lifted, and the weight W 4 (g) (the weight of the support cylinder, the swollen water-absorbing resin (or particulate water-absorbing agent) and the piston) after removing the load was measured again. Then, from these weights W 3 and W 4 , the absorption capacity (g / g) under pressure at 1.9 kPa with respect to a 0.90 wt% sodium chloride aqueous solution (physiological saline) was calculated according to the following formula.
0.90重量%塩化ナトリウム水溶液(生理食塩水)に対する1.9kPaでの加圧下吸収倍率(g/g)=(重量W4(g)−重量W3 (g))/吸水性樹脂(または粒子状吸水剤)の重量(g)
(6)含水率補正した加圧下吸収倍率(g/g)
含水率補正した加圧下吸収倍率は、吸水性樹脂(または粒子状吸水剤)の含水率が0重量%と仮定した場合の加圧下吸収倍率であり、次式に従って算出した。
Absorption capacity under load at 1.9 kPa (g / g) with respect to 0.90 wt% sodium chloride aqueous solution (saline) = (weight W 4 (g) −weight W 3 (g)) / water absorbent resin (or Weight of particulate water-absorbing agent (g)
(6) Absorption capacity under pressure corrected for water content (g / g)
The absorption capacity under pressure corrected for water content is the absorption capacity under pressure when the water content of the water-absorbent resin (or particulate water-absorbing agent) is assumed to be 0% by weight, and was calculated according to the following formula.
含水率補正した加圧下吸収倍率(g/g)=(加圧下吸収倍率(g/g)+含水率(重量%)/100)/(1−含水率(重量%)/100)
(7)耐衝撃テスト
吸水性樹脂(または粒子状吸水剤)の耐衝撃テストは以下のように行った。即ち吸水性樹脂(または粒子状吸水剤)をそれぞれ30gずつ量り取り、予め用意しておいたガラス玉(6〜7mmφ)10gを入れた250mlのマヨネーズ瓶(55mmφ×110mm)1本ずつにそれぞれ入れ、蓋を閉めた。ペイントシェーカー(トーヨ精機株式会社製)にそのマヨネーズ瓶を4本セットし、10分間ペイントシェーカーを作動し、その後マヨネーズ瓶から吸水性樹脂(または粒子状吸水剤)を取り出した。
Absorption capacity under pressure corrected (g / g) = (Absorption capacity under pressure (g / g) + Moisture content (% by weight) / 100) / (1−Moisture content (% by weight) / 100)
(7) Impact resistance test The impact resistance test of the water-absorbent resin (or particulate water-absorbing agent) was performed as follows. That is, weigh each 30 g of water-absorbing resin (or particulate water-absorbing agent) and put it in each 250 ml mayonnaise bottle (55 mmφ × 110 mm) containing 10 g of glass beads (6-7 mmφ) prepared in advance. , Closed the lid. Four mayonnaise bottles were set in a paint shaker (manufactured by Toyo Seiki Co., Ltd.), the paint shaker was operated for 10 minutes, and then the water absorbent resin (or particulate water absorbing agent) was taken out from the mayonnaise bottle.
<可溶分(水可溶成分)量>
250ml容量の蓋付きプラスチック容器に0.90重量%塩化ナトリウム水溶液(生理食塩水)の184.3gを量り取り、その水溶液中に試料1.00gを加え、フッ素樹脂でコーティングされた、直径7mm(中央部の直径は8mm)、長さ30mmの円柱状スターラーチップを用いて、300rpm±30rpmで16時間攪拌することにより試料中の可溶分を抽出した。抽出液を濾紙を用いて濾過し、濾液を50.0g量り取って測定溶液とした。
<Amount of soluble component (water-soluble component)>
A plastic container with a lid with a capacity of 250 ml was weighed 184.3 g of 0.90% by weight aqueous sodium chloride solution (saline), 1.00 g of a sample was added to the aqueous solution, and the diameter was 7 mm (coated with fluororesin). The soluble part in the sample was extracted by stirring at 300 rpm ± 30 rpm for 16 hours using a cylindrical stirrer chip having a diameter of 8 mm at the center and a length of 30 mm. The extract was filtered using filter paper, and 50.0 g of the filtrate was weighed to obtain a measurement solution.
はじめに生理食塩水だけを、まず、0.1Nの水酸化ナトリウム水溶液でpH10まで滴定を行い、その後、0.1Nの塩酸でpH2.7まで滴定して空滴定量([bNaOH]ml、[bHCl]ml)を得た。同様の滴定操作を測定溶液についても行うことにより、滴定量([NaOH]ml、[HCl]ml)を求めた。 First, physiological saline alone was titrated to pH 10 with a 0.1N aqueous sodium hydroxide solution, and then titrated to pH 2.7 with 0.1N hydrochloric acid, followed by empty titration ([bNaOH] ml, [bHCl] Ml) was obtained. By performing the same titration operation on the measurement solution, titration amounts ([NaOH] ml, [HCl] ml) were obtained.
例えば試料が既知量のアクリル酸とそのナトリウム塩とからなる吸水性樹脂の場合、そのモノマーの平均分子量と上記操作により得られた滴定量をもとに、吸水性樹脂中の可溶分量を以下の計算式により算出することができる。未知量の場合は滴定により求めた中和率を用いてモノマーの平均分子量を算出する。 For example, if the sample is a water-absorbing resin composed of a known amount of acrylic acid and its sodium salt, the soluble content in the water-absorbing resin is determined as follows based on the average molecular weight of the monomer and the titration amount obtained by the above operation. It can be calculated by the following formula. In the case of an unknown amount, the average molecular weight of the monomer is calculated using the neutralization rate obtained by titration.
可溶分(重量%)=0.1×(平均分子量)×184.3×100×([HCl]−[bHCl])/1000/1.0/50.0
中和率(mol%)=(1−([NaOH]−[bNaOH])/([HCl]−[bHCl]))×100
<0.90重量%塩化ナトリウム水溶液(生理食塩水)に対する1.9kPaでの加圧下吸収倍率(AAP1.9kPa)>
目開き38μmのステンレス製金網を円筒断面の一辺(底)に溶着させた内径60mmのプラスチック製支持円筒の底の金網上に、試料0.90gを均一に散布し、その上に外径が60mmよりわずかに小さく支持円筒との壁面に隙間が生じず、かつ上下の動きは妨げられないピストン(cover plate)を載置し、支持円筒、試料およびピストンの重量W3 (g)を測定した。
Soluble content (% by weight) = 0.1 × (average molecular weight) × 184.3 × 100 × ([HCl] − [bHCl]) / 1000 / 1.0 / 50.0
Neutralization rate (mol%) = (1 − ([NaOH] − [bNaOH]) / ([HCl] − [bHCl])) × 100
<Absorption capacity under pressure (AAP 1.9 kPa) at 1.9 kPa with respect to 0.90 wt% sodium chloride aqueous solution (saline)>
0.90 g of a sample is uniformly dispersed on a metal mesh at the bottom of a plastic support cylinder having an inner diameter of 60 mm, in which a stainless steel mesh having a mesh opening of 38 μm is welded to one side (bottom) of the cylindrical cross section, and an outer diameter of 60 mm is applied thereon. A piston (cover plate) that is slightly smaller and has no gap on the wall surface with the support cylinder and that does not prevent vertical movement was placed, and the weight W 3 (g) of the support cylinder, sample, and piston was measured.
このピストン上に、試料に対して、ピストンを含め1.9kPaの荷重を均一に加えることができるように調整された荷重を載置し、測定装置一式を完成させた。直径150mmのペトリ皿の内側に直径90mm、厚さ5mmのガラスフィルターを置き、25±2℃に調温した0.90重量%塩化ナトリウム水溶液(生理食塩水)をガラスフィルターの上部面と同レベルになるように加えた。その上に直径9cmの濾紙(トーヨー濾紙(株)製、No.2)を1枚載せて表面が全て濡れるようにし、かつ過剰の液を除いた。 On this piston, a load adjusted so that a load of 1.9 kPa including the piston can be uniformly applied to the sample was placed, and a complete measuring apparatus was completed. Place a glass filter with a diameter of 90 mm and a thickness of 5 mm inside a Petri dish with a diameter of 150 mm, and 0.90 wt% sodium chloride aqueous solution (saline) adjusted to 25 ± 2 ° C at the same level as the upper surface of the glass filter It was added to become. On top of that, a sheet of 9 cm diameter filter paper (Toyo Filter Paper Co., Ltd., No. 2) was placed so that the entire surface was wetted, and excess liquid was removed.
上記測定装置一式を上記湿った濾紙上にのせ、液を荷重下で吸収させた。液面がガラスフィルターの上部から低下したら液を追加し、液面レベルを一定に保った。60分後に測定装置一式を持ち上げ、荷重を取り除いた重量W4(g)(支持円筒、膨潤した試料、およびピストンの重量)を再測定した。そして、これら重量W3 、W4 から、次式に従って、0.90重量%塩化ナトリウム水溶液(生理食塩水)に対する1.9kPaでの加圧下吸収倍率(g/g)を算出した。 The set of measuring devices was placed on the wet filter paper, and the liquid was absorbed under load. When the liquid level dropped from the top of the glass filter, the liquid was added to keep the liquid level constant. After 60 minutes, the set of measuring devices was lifted and the weight W 4 (g) (weight of the supporting cylinder, swollen sample, and piston) after removing the load was measured again. Then, from these weights W 3 and W 4 , the absorption capacity (g / g) under pressure at 1.9 kPa with respect to a 0.90 wt% sodium chloride aqueous solution (physiological saline) was calculated according to the following formula.
AAP1.9kPa(g/g)=(重量W4(g)−重量W3 (g))/試料の重量(g)
<0.90重量%塩化ナトリウム水溶液(生理食塩水)に対する4.8kPaでの加圧下吸収倍率(AAP4.8kPa)>
0.90重量%塩化ナトリウム水溶液(生理食塩水)に対する1.9kPaでの加圧下吸収倍率の測定において、ピストンの荷重を4.8kPaに変更した以外は、同様の操作を行うことにより測定した。
AAP 1.9 kPa (g / g) = (weight W 4 (g) −weight W 3 (g)) / weight of sample (g)
<Absorption capacity under pressure (AAP 4.8 kPa) at 4.8 kPa with respect to 0.90 wt% sodium chloride aqueous solution (saline)>
In the measurement of the absorption capacity under pressure at 1.9 kPa against a 0.90% by weight sodium chloride aqueous solution (physiological saline), the measurement was performed by performing the same operation except that the piston load was changed to 4.8 kPa.
0.90重量%塩化ナトリウム水溶液(生理食塩水)に対する4.8kPaでの加圧下吸収倍率(g/g)は次式により求められる。 The absorption capacity (g / g) under pressure at 4.8 kPa with respect to a 0.90% by weight sodium chloride aqueous solution (saline) is obtained by the following equation.
AAP4.8kPa(g/g)=(重量W4(g)−重量W3 (g))/試料の重量(g)
<嵩比重、流下速度>
嵩比重測定器(蔵持科学機器製作所製)を用い、JIS K 3362に準じて測定した。粒度による偏りを無くすため十分に混合された試料(吸水性樹脂粒子)100gをダンパーを閉めた漏斗に入れた後、速やかにダンパーを開け、試料を受器に落とした。試料を落とし始めてから、落としきるまでの時間(秒)を流下速度とする。受器から盛り上がった試料は、ガラス棒ですり落とした後、試料の入った受器の重さを0.1gまで正確に量り、次の式によって嵩比重を算出した。
AAP 4.8 kPa (g / g) = (weight W 4 (g) −weight W 3 (g)) / weight of sample (g)
<Bulk specific gravity, flow velocity>
It measured according to JISK3362 using the bulk specific gravity measuring device (made by Kuramochi Scientific Instruments Seisakusho). In order to eliminate unevenness due to particle size, 100 g of a sufficiently mixed sample (water-absorbing resin particles) was placed in a funnel with a damper closed, and then the damper was quickly opened and the sample was dropped into a receiver. The time (seconds) from when the sample starts to drop to when it is dropped is taken as the flow velocity. The sample swelled from the receiver was scraped off with a glass rod, and the weight of the receiver containing the sample was accurately weighed to 0.1 g, and the bulk specific gravity was calculated by the following equation.
嵩比重(g/ml)=(試料の入った受器の重さ(g)−受器の重さ(g))/受器の内容積(100ml)
なお、測定時の温度は25±2℃であり、相対湿度は30RH%以上50RH%以下であった。
Bulk specific gravity (g / ml) = (Weight of receiver containing sample (g) −Weight of receiver (g)) / Receiver internal volume (100 ml)
The temperature at the time of measurement was 25 ± 2 ° C., and the relative humidity was 30 RH% or more and 50 RH% or less.
<ペイントシェーカーテスト(プロセスダメージ)>
ペイントシェーカーテスト(PS)とは、直径6cm、高さ11cmのガラス製容器に、直径6mmのガラスビーズ10g、試料30gを入れてペイントシェーカー(東洋製機製作所 製品No.488)に取り付け、800cycle/min(CPM)で振盪するものであり、装置詳細は特開平9−235378号公報に開示されている。本実施例、比較例では、振盪時間は10分間とした。
<Paint shaker test (process damage)>
The paint shaker test (PS) is a glass container having a diameter of 6 cm and a height of 11 cm, and 10 g of glass beads having a diameter of 6 mm and a sample of 30 g are placed on a paint shaker (Toyo Seisakusho Co., Ltd. product No. 488), and 800 cycles / The apparatus is shaken with min (CPM), and details of the apparatus are disclosed in Japanese Patent Laid-Open No. 9-235378. In this example and comparative example, the shaking time was 10 minutes.
振盪後、目開き2mmのJIS標準篩でガラスビーズを除去し、プロセスダメージを与えられた試料を得る。 After shaking, the glass beads are removed with a JIS standard sieve having an opening of 2 mm to obtain a sample with process damage.
<ダマ量の定量>
硬化工程後の吸水性樹脂造粒物あるいは、更にプロセスダメージを与えた吸水性樹脂造粒物10.00gを、目開き850μmを有する篩(The IIDA TESTING SIEVE:内径80mm)に仕込み、ロータップ型ふるい振盪機((株)飯田製作所製、ES−65型ふるい振盪機)により5分間分級した。
<Quantification of the amount of lumps>
The water-absorbent resin granulated product after the curing step or the water-absorbent resin granulated product further damaged by the process is charged into a sieve having a mesh opening of 850 μm (The IIDA TESTING SIVE: inner diameter 80 mm), and a low tap type sieve. Classification was carried out for 5 minutes using a shaker (manufactured by Iida Seisakusho, ES-65 type sieve shaker).
5分後に、篩に仕込んだ全吸水性樹脂造粒物量(10.00g)中の850μmの篩上に残っている吸水性樹脂造粒物量の割合を算出し、ダマ量とした。すなわち、ダマ量は以下の式で求められる。 After 5 minutes, the ratio of the amount of the water-absorbent resin granule remaining on the 850 μm sieve in the total amount of the water-absorbent resin granule (10.00 g) charged in the sieve was calculated and used as the amount of waste. That is, the amount of lumps is obtained by the following formula.
ダマ量(重量%)=(850μmの篩上に残っている吸水性樹脂造粒物量)/篩に仕込んだ全吸水性樹脂造粒物量)×100
<重量平均粒子径(D50)および対数標準偏差(σζ)>
試料を、850μm、710μm、600μm、500μm、425μm、300μm、212μm、150μm、106μm、75μm、45μmのJIS標準篩で篩い分けし、残留百分率を対数確率紙にプロットした。なお、試料の粒径により、篩は必要により適宜追加して測定する。これにより、R=50重量%に相当する粒子径を重量平均粒子径(D50)として読み取った。また、粒度分布の対数標準偏差(σζ)は下記の式で表され、σζの値が小さいほど粒度分布が狭いことを意味する。
Dama amount (% by weight) = (Amount of water absorbent resin granule remaining on 850 μm sieve) / Total amount of water absorbent resin granule charged in sieve) × 100
<Weight average particle diameter (D50) and logarithmic standard deviation (σζ)>
The sample was sieved with JIS standard sieves of 850 μm, 710 μm, 600 μm, 500 μm, 425 μm, 300 μm, 212 μm, 150 μm, 106 μm, 75 μm, 45 μm, and the residual percentage was plotted on log probability paper. Depending on the particle size of the sample, a sieve is added as necessary and measured. Thereby, the particle diameter corresponding to R = 50% by weight was read as the weight average particle diameter (D50). Further, the logarithmic standard deviation (σζ) of the particle size distribution is expressed by the following equation, and the smaller the value of σζ, the narrower the particle size distribution.
σζ=0.5×ln(X2/X1)
(X1はR=84.1%、X2はR=15.9%のときのそれぞれの粒子径)
篩い分けは試料10.00gを、目開き850μm、710μm、600μm、500μm、425μm、300μm、212μm、150μm、106μm、75μm、45μmなどのJIS標準ふるい(The IIDA TESTING SIEVE:内径80mm)に仕込み、ロータップ型ふるい振盪機((株)飯田製作所製、ES−65型ふるい振盪機)により5分間分級した。
σζ = 0.5 × ln (X2 / X1)
(X1 is R = 84.1%, X2 is each particle size when R = 15.9%)
For sieving, a sample of 10.00 g is charged into a JIS standard sieve (The IIDA TESTING SIEVE: inner diameter 80 mm) such as an opening of 850 μm, 710 μm, 600 μm, 500 μm, 425 μm, 300 μm, 212 μm, 150 μm, 106 μm, 75 μm, 45 μm. Classification was carried out for 5 minutes using a type sieve shaker (manufactured by Iida Seisakusho, ES-65 type sieve shaker).
なお、重量平均粒子径(D50)とは、米国特許5051259号公報などにあるように一定目開きの標準ふるいで粒子全体の50重量%に対応する標準ふるいの粒子径のことである。 The weight average particle diameter (D50) is a particle diameter of a standard sieve corresponding to 50% by weight of the whole particle with a standard sieve having a constant mesh as described in US Pat. No. 5,051,259.
<Vortex>
JIS K7224−1996に準拠するが、試験液(0.9重量%塩化ナトリウム水溶液)の温度は、30℃±1℃で行い、スターラーチップの長さは、40mmのものを用いて測定した。
<Vortex>
According to JIS K7224-1996, the temperature of the test solution (0.9 wt% sodium chloride aqueous solution) was 30 ° C. ± 1 ° C., and the length of the stirrer chip was measured using a 40 mm one.
<pass150μm>
上記重量平均粒子径(D50)を測定した目開き150μmのJIS標準篩を通過した試料ないし篩に仕込んだ全試料から、次式に従って、Pass150μm割合(%)を算出した。
<Pass 150 μm>
Based on the following formula, the ratio (%) of Pass 150 μm was calculated from a sample that passed through a JIS standard sieve having a mesh size of 150 μm and whose weight average particle diameter (D50) was measured.
Pass150μm割合(%)=(目開き150μmのJIS標準篩を通過した試料の重量(g)/篩に仕込んだ試料全体の重量(g))×100
<無機微粒子含有量>
無機微粒子含有量とは、吸水性樹脂造粒物100重量部に対し無機微粒子が含まれている割合を示すものである。
Pass 150 μm ratio (%) = (weight of the sample passed through a JIS standard sieve having an opening of 150 μm (g) / weight of the entire sample charged in the sieve (g)) × 100
<Inorganic fine particle content>
The content of inorganic fine particles indicates the proportion of inorganic fine particles contained in 100 parts by weight of the water absorbent resin granulated product.
吸水性樹脂造粒物に含まれる無機微粒子を定量する場合、該吸水性樹脂造粒物中に含まれる無機微粒子の元素をEPMA(Electron Probe Micro-Analysis) やSEM―EDS(Scanning Electron Microscopy・Energy Dispersion X-ray Spectrometry)によって定性分析を行った後、該吸水性樹脂造粒物中に含まれる無機微粒子元素を蛍光X線分析によって定量することにより、吸水性樹脂造粒物中に含まれる無機微粒子含有量を決定した。 When quantifying the inorganic fine particles contained in the water-absorbent resin granulated product, the elements of the inorganic fine particles contained in the water-absorbent resin granulated product are changed to EPMA (Electron Probe Micro-Analysis) or SEM-EDS (Scanning Electron Microscopy / Energy). After conducting qualitative analysis by Dispersion X-ray Spectrometry), inorganic inorganic elements contained in the water-absorbent resin granulated product are quantified by fluorescent X-ray analysis by quantifying the inorganic fine particle elements contained in the water-absorbent resin granulated product. The fine particle content was determined.
(製造例1)
吸水性樹脂調合物(C)および吸水性樹脂分級物(D)の製造
シグマ型羽根を2本有する内容積10リットルのジャケット付きステンレス製双腕型ニーダーに蓋を付けて形成した反応器中で、75モル%の中和率を有するアクリル酸ナトリウムの水溶液6600g(不飽和単量体濃度37.7重量%)にポリエチレングリコールジアクリレート(n=9)5.30gを溶解させて反応液とした。次にこの反応液を窒素ガス雰囲気下で、20分間窒素置換した。続いて、反応液に10重量%過硫酸ナトリウム水溶液39.6gおよび1重量%L−アスコルビン酸水溶液1.39gを攪拌しながら添加したところ、およそ30秒後に重合が開始した。そして、生成したゲルを粉砕しながら、20〜95℃で重合を行い、重合が開始して45分後に含水ゲル状架橋重合体を取り出した。得られた含水ゲル状架橋重合体は、その径が約5mm以下に細分化されていた。この細分化された含水ゲル状架橋重合体を目開き850μmのJIS標準篩の金網上に広げて180℃で35分間熱風乾燥し、吸水性樹脂(A)を得た。次いで、ロール粉砕機(WML型、有限会社井ノ口技研)を用いて粉砕し、さらに目開き850μmのJIS標準篩で分級調合をおこなって850μm通過の吸水性樹脂を得た。
(Production Example 1)
Production of water-absorbing resin formulation (C) and water-absorbing resin classification (D) In a reactor formed by attaching a lid to a 10-liter jacketed stainless steel double-arm kneader having two sigma type blades , 5.30 g of polyethylene glycol diacrylate (n = 9) was dissolved in 6600 g of an aqueous solution of sodium acrylate having a neutralization rate of 75 mol% (unsaturated monomer concentration: 37.7 wt%) to obtain a reaction solution. . Next, the reaction solution was purged with nitrogen for 20 minutes in a nitrogen gas atmosphere. Subsequently, 39.6 g of a 10 wt% aqueous sodium persulfate solution and 1.39 g of a 1 wt% aqueous L-ascorbic acid solution were added to the reaction solution with stirring. Polymerization started after about 30 seconds. Then, polymerization was performed at 20 to 95 ° C. while pulverizing the generated gel, and a hydrogel crosslinked polymer was taken out 45 minutes after the polymerization started. The obtained hydrogel crosslinked polymer was subdivided to have a diameter of about 5 mm or less. This finely divided hydrogel crosslinked polymer was spread on a wire mesh of a JIS standard sieve having an opening of 850 μm and dried with hot air at 180 ° C. for 35 minutes to obtain a water absorbent resin (A). Next, the mixture was pulverized using a roll pulverizer (WML type, Inoguchi Giken Co., Ltd.), and further classified and mixed with a JIS standard sieve having an opening of 850 μm to obtain a water-absorbing resin that passed 850 μm.
該吸水性樹脂100重量部に対して、エチレングリコールジグリシジルエーテル0.03重量部/プロピレングリコール0.9重量部/水3重量部からなる架橋剤溶液3.93重量部を混合し、モルタル型混合器に該混合物を添加し、190℃で45分間加熱処理を行った。こうして得られた加熱処理物を目開き850μmのJIS標準篩で分級し、850μm通過の吸水性樹脂(B)を得た。この吸水性樹脂(B)の重量平均粒子径は275μmで150μm通過の微粉末割合は9.5重量%であり、無加圧下吸収倍率は32.2g/g、加圧下吸収倍率は30.7g/gであり、含水率は4.0重量%であった。更に吸水性樹脂(B)をターボスクリーナー(ターボ工業株式会社製)を用いて、目開き500μm、425μm、300μm、212μm、150μmの円筒スクリーンで分級した。分級して得た500μm通過425μm未通過部分、425μm通過300μm未通過部分、300μm通過212μm未通過部分、212μm通過150μm未通過部分のそれぞれの粒度の吸水性樹脂を調合して500μm通過150μm未通過部分の吸水性樹脂調合物(C)と150μm通過部分の吸水性樹脂分級物(D)とを得た。吸水性樹脂調合物(C)の重量平均粒子径は288μmであり、また、吸水性樹脂分級物(D)の平均粒子径は125μmであった。 To 100 parts by weight of the water-absorbent resin, 3.93 parts by weight of a crosslinking agent solution composed of 0.03 parts by weight of ethylene glycol diglycidyl ether / 0.9 parts by weight of propylene glycol / 3 parts by weight of water is mixed to form a mortar type. The mixture was added to the mixer and heat-treated at 190 ° C. for 45 minutes. The heat-treated product thus obtained was classified with a JIS standard sieve having an opening of 850 μm to obtain a water-absorbing resin (B) passing through 850 μm. The water-absorbent resin (B) has a weight average particle size of 275 μm and a fine powder ratio of 9.5% by weight passing through 150 μm. The absorption capacity under no pressure is 32.2 g / g, and the absorption capacity under pressure is 30.7 g. / G, and the water content was 4.0% by weight. Further, the water absorbent resin (B) was classified with a cylindrical screen having openings of 500 μm, 425 μm, 300 μm, 212 μm, and 150 μm using a turbo screener (manufactured by Turbo Industry Co., Ltd.). 500 μm passing part 425 μm not passing part, 425 μm passing part 300 μm not passing part, 300 μm passing part 212 μm not passing part, 212 μm passing part 150 μm not passing part, 500 μm passing part 150 μm passing part Water-absorbent resin formulation (C) and 150 μm-passage water-absorbent resin classified product (D) were obtained. The weight average particle size of the water absorbent resin formulation (C) was 288 μm, and the average particle size of the water absorbent resin classified product (D) was 125 μm.
(製造例2)
吸水性樹脂分級物(F)および(G)の製造
参考例1で得た吸水性樹脂(A)を、ロール粉砕機(WML型、有限会社井ノ口技研)を用いて粉砕し、さらに目開き850μmのJIS標準篩で分級調合を行って得た850μm通過の吸水性樹脂100重量部に対して、エチレングリコールジグリシジルエーテル0.03重量部/プロピレングリコール1.0重量部/水3重量部からなる架橋剤溶液4.03重量部を混合し、モルタル型混合器に該混合物を添加し、190℃で40分間加熱処理を行った。こうして得られた加熱処理物を目開き850μmのJIS標準篩で分級し、850μm通過の吸水性樹脂(E)を得た。この吸水性樹脂(E)の重量平均粒子径は297μmで150μm通過の微粉末割合は9.4重量%であり、無加圧下吸収倍率は32.4g/g、加圧下吸収倍率は30.9g/gであり、含水率は3.9重量%であった。更に吸水性樹脂(E)をサニタリーミノックスシフター(株式会社西村機械製作所製)を用いて、目開き150μmの篩で分級して、850μm通過150μm未通過部分の吸水性樹脂分級物(F)と150μm通過部分の吸水性樹脂分級物(G)とを得た。吸水性樹脂分級物(F)の重量平均粒子径は293μmであり、また、吸水性樹脂分級物(G)の重量平均粒子径は120μmであった。
(Production Example 2)
Manufacture of water-absorbent resin classification products (F) and (G) The water-absorbent resin (A) obtained in Reference Example 1 was pulverized using a roll pulverizer (WML type, Inoguchi Giken Co., Ltd.), and further an opening of 850 μm. It consists of 0.03 part by weight of ethylene glycol diglycidyl ether / 1.0 part by weight of propylene glycol / 3 parts by weight of water with respect to 100 parts by weight of the water-absorbing resin passing through 850 μm obtained by classifying and preparing with a JIS standard sieve. 4.03 parts by weight of the crosslinking agent solution was mixed, the mixture was added to a mortar type mixer, and heat treatment was performed at 190 ° C. for 40 minutes. The heat-treated product thus obtained was classified with a JIS standard sieve having an opening of 850 μm to obtain a water-absorbing resin (E) that passed through 850 μm. The water-absorbent resin (E) has a weight average particle size of 297 μm, the proportion of fine powder passing through 150 μm is 9.4% by weight, the absorption capacity under no pressure is 32.4 g / g, and the absorption capacity under pressure is 30.9 g. / G, and the water content was 3.9% by weight. Further, the water-absorbent resin (E) is classified with a sanitary minox shifter (manufactured by Nishimura Machinery Co., Ltd.) with a sieve having a mesh opening of 150 μm, and the water-absorbent resin classification product (F) of the 850 μm passage 150 μm non-passage portion and 150 μm A water-absorbent resin classification product (G) at the passing portion was obtained. The weight average particle diameter of the water absorbent resin classified product (F) was 293 μm, and the weight average particle diameter of the water absorbent resin classified product (G) was 120 μm.
(製造例3)
吸水性樹脂分級物(I)および(J)の製造
参考例1で得た吸水性樹脂(A)を、ロール粉砕機(WML型、有限会社井ノ口技研)を用いて粉砕し、さらに目開き850μmのJIS標準篩で分級調合を行って得た850μm通過の吸水性樹脂100重量部に対して、エチレングリコールジグリシジルエーテル0.029重量部/プロピレングリコール1.0重量部/水3重量部からなる架橋剤溶液4.03重量部を混合し、モルタル型混合器に該混合物を添加し、190℃で40分間加熱処理を行った。こうして得られた加熱処理物を目開き850μmのJIS標準篩で分級し、850μm通過の吸水性樹脂(H)を得た。この吸水性樹脂(H)の重量平均粒子径は263μmで150μm通過の微粉末割合は8.7重量%であり、また45μm通過の割合は0.0重量%であり、無加圧下吸収倍率は32.7g/g、加圧下吸収倍率は31.2g/gであり、含水率は4.2重量%であった。更に吸水性樹脂(H)を目開き850μmのJIS標準篩で分級し、を用いて、850μm通過150μm未通過部分の吸水性樹脂分級物(I)と150μm通過部分の吸水性樹脂分級物(J)とを得た。吸水性樹脂分級物(I)の重量平均粒子径は293μmであり、また、吸水性樹脂分級物(J)の重量平均粒子径は118μmであった。
(Production Example 3)
Manufacture of water-absorbent resin classification products (I) and (J) The water-absorbent resin (A) obtained in Reference Example 1 was pulverized using a roll pulverizer (WML type, Inoguchi Giken Co., Ltd.), and further an opening of 850 μm. It consists of 0.029 parts by weight of ethylene glycol diglycidyl ether / 1.0 part by weight of propylene glycol / 3 parts by weight of water with respect to 100 parts by weight of the water-absorbing resin passing through 850 μm obtained by classifying and preparing with a JIS standard sieve. 4.03 parts by weight of the crosslinking agent solution was mixed, the mixture was added to a mortar type mixer, and heat treatment was performed at 190 ° C. for 40 minutes. The heat-treated product thus obtained was classified with a JIS standard sieve having an aperture of 850 μm to obtain a water absorbent resin (H) that passed through 850 μm. The weight average particle diameter of this water absorbent resin (H) is 263 μm, the proportion of fine powder passing through 150 μm is 8.7 wt%, the proportion passing through 45 μm is 0.0 wt%, and the absorption capacity under no pressure is The absorption capacity under pressure was 32.7 g / g, the water content was 4.2% by weight. Further, the water-absorbing resin (H) is classified with a JIS standard sieve having an opening of 850 μm, and using 850 μm, the water-absorbing resin classification product (I) of the portion where 850 μm passes and 150 μm does not pass and the water-absorbing resin classification product (J ) And got. The weight average particle diameter of the water absorbent resin classified product (I) was 293 μm, and the weight average particle diameter of the water absorbent resin classified product (J) was 118 μm.
(製造例4)
中和重合による吸水性樹脂粒子(K)の製造
シグマ型羽根を2本有する内容積10リットルのジャケット付きステンレス製双腕型ニーダーに蓋を付けて形成した反応器中で、75モル%の中和率を有するアクリル酸ナトリウムの水溶液6600g(単量体濃度40.0重量%)にポリエチレングリコールジアクリレート(n=9)5.45gを溶解させて反応液とした。次にこの反応液を窒素ガス雰囲気下で、20分間脱気した。続いて、反応液に10重量%過硫酸ナトリウム水溶液35.8gおよび1重量%L−アスコルビン酸水溶液1.49gを攪拌しながら添加したところ、およそ20秒後に重合が開始した。
(Production Example 4)
Production of water-absorbing resin particles (K) by neutralization polymerization In a reactor formed by attaching a cover to a stainless steel double-armed kneader with two sigma-shaped blades and having a volume of 10 liters, the inner volume of 75 mol% A reaction solution was prepared by dissolving 5.45 g of polyethylene glycol diacrylate (n = 9) in 6600 g (monomer concentration: 40.0% by weight) of an aqueous solution of sodium acrylate having a sum ratio. Next, this reaction solution was degassed for 20 minutes in a nitrogen gas atmosphere. Subsequently, 35.8 g of a 10 wt% aqueous sodium persulfate solution and 1.49 g of a 1 wt% aqueous L-ascorbic acid solution were added to the reaction solution with stirring, and polymerization started after about 20 seconds.
そして、生成したゲルを粉砕しながら、20(開始)℃以上95℃(ピーク)以下で重合を行い、重合が開始して42分後に含水ゲル状架橋重合体を取り出した。得られた含水ゲル状架橋重合体は、その径が約5mm以下に細分化されていた。この細分化された含水ゲル状架橋重合体を20メッシュ(目開き850μm)の金網上に広げ、180℃で40分間熱風乾燥した。 Then, polymerization was performed at 20 (start) ° C. or higher and 95 ° C. (peak) or lower while pulverizing the generated gel, and a hydrogel crosslinked polymer was taken out 42 minutes after the polymerization started. The obtained hydrogel crosslinked polymer was subdivided to have a diameter of about 5 mm or less. This finely divided hydrogel crosslinked polymer was spread on a 20 mesh (mesh 850 μm) wire mesh and dried with hot air at 180 ° C. for 40 minutes.
次いで、ロールミルを用いて粉砕し、さらに目開き850μmのJIS標準篩で分級調合することで、重量平均粒径366μmでかつ600μm以上850μm未満の粒子径を有する樹脂の割合が3.2重量%、150μm未満の粒子径を有する樹脂の割合が3.3重量%、対数標準偏差(σζ)が0.377、含水率6重量%である不定形破砕状の吸水性樹脂粒子(K)を得た。 Next, the mixture is pulverized using a roll mill and further classified and prepared with a JIS standard sieve having an opening of 850 μm, so that the ratio of the resin having a weight average particle size of 366 μm and a particle size of 600 μm or more and less than 850 μm is 3.2% by weight, Amorphous crushed water-absorbent resin particles (K) having a proportion of resin having a particle diameter of less than 150 μm of 3.3% by weight, a logarithmic standard deviation (σζ) of 0.377, and a moisture content of 6% by weight were obtained. .
得られた吸水性樹脂粒子(K)の物性を測定したところ、CRC(0.90重量%塩化ナトリウム水溶液(生理食塩水)に対する無加圧下吸収倍率)=47.0(g/g)、可溶分量は15.0重量%であった。 When the physical properties of the water-absorbing resin particles (K) obtained were measured, CRC (absorption capacity under no pressure with respect to 0.90 wt% sodium chloride aqueous solution (saline)) = 47.0 (g / g), acceptable The dissolved amount was 15.0% by weight.
該得られた吸水性樹脂粒子(K)500gを5Lレーディゲミキサー(M5R型レーディゲ社製)に入れ、該レーディゲミキサーの主軸(鋤状羽根)を330rpmで回転させながら、デナコール/1,4−ブタンジオール/プロピレングリコール/水=0.03/0.32/0.5/2.73重量%混合溶液17.9gをスプレーにより噴霧しながら投入し1分間混合した。その後撹拌を停止し、得られた混合物を速やかに取り出した。 500 g of the obtained water-absorbent resin particles (K) were put into a 5 L Ladige mixer (manufactured by M5R type Ladige), and while the main shaft (squilled blade) of the Ladige mixer was rotated at 330 rpm, Denacol / 1 , 4-butanediol / propylene glycol / water = 0.03 / 0.32 / 0.5 / 2.73 wt% mixed solution 17.9 g was added while spraying and mixed for 1 minute. Stirring was then stopped and the resulting mixture was quickly removed.
次に、得られた該混合物を、オイルバスにより容器を210℃に加熱された5Lモルタルミキサー(西日本試験機製作所製)に投入し、該混合物に均一に熱が加わるように撹拌混合した。約30分後、該モルタルミキサーより該混合物を取り出し、その全量を850μmのJIS標準篩を通過させ、表面処理された吸水性樹脂粒子(K)を得た。表面処理された吸水性樹脂粒子(K)の物性を表3に示す。 Next, the obtained mixture was put into a 5 L mortar mixer (manufactured by West Japan Testing Machine Co., Ltd.) whose container was heated to 210 ° C. by an oil bath, and stirred and mixed so that heat was uniformly applied to the mixture. After about 30 minutes, the mixture was taken out from the mortar mixer, and the entire amount was passed through a 850 μm JIS standard sieve to obtain surface-treated water-absorbent resin particles (K). Table 3 shows the physical properties of the surface-treated water-absorbent resin particles (K).
(製造例5)
中和重合による吸水性樹脂粒子(L)の製造
シグマ型羽根を2本有する内容積10リットルのジャケット付きステンレス製双腕型ニーダーに蓋を付けて形成した反応器中で、75モル%の中和率を有するアクリル酸ナトリウムの水溶液6600g(単量体濃度40.0重量%)にポリエチレングリコールジアクリレート(n=9)5.45gを溶解させて反応液とした。次にこの反応液を窒素ガス雰囲気下で、20分間脱気した。続いて、反応液を攪拌しながら10重量%過硫酸ナトリウム水溶液35.8gおよび1重量%L−アスコルビン酸水溶液1.49g添加をしたところ、およそ20秒後に重合が開始された。
(Production Example 5)
Production of water-absorbing resin particles (L) by neutralization polymerization In a reactor formed by attaching a lid to a stainless steel double-armed kneader with a volume of 10 liters and having two sigma-type blades, A reaction solution was prepared by dissolving 5.45 g of polyethylene glycol diacrylate (n = 9) in 6600 g (monomer concentration: 40.0% by weight) of an aqueous solution of sodium acrylate having a sum ratio. Next, this reaction solution was degassed for 20 minutes in a nitrogen gas atmosphere. Subsequently, 35.8 g of a 10 wt% aqueous sodium persulfate solution and 1.49 g of a 1 wt% L-ascorbic acid aqueous solution were added while stirring the reaction solution, and polymerization was started after about 20 seconds.
そして、生成したゲルを粉砕しながら、20(開始)℃以上95℃(ピーク)以下で重合を行い、重合が開始して42分後に含水ゲル状架橋重合体を取り出した。得られた含水ゲル状架橋重合体は、その径が約5mm以下に細分化されていた。この細分化された含水ゲル状架橋重合体を20メッシュ(目開き850μm)の金網上に広げ、180℃で40分間熱風乾燥した。次いで、ロールミルを用いて粉砕し、さらに目開き600μmのJIS標準篩で分級調合することで、重量平均粒径270μmでかつ500μm以上600μm未満の粒子径を有する樹脂の割合が0.2重量%、150μm未満の粒子径を有する樹脂の割合が9.0重量%、対数標準偏差(σζ)が0.365、含水率6重量%である不定形破砕状の吸水性樹脂粒子(L)を得た。 Then, polymerization was performed at 20 (start) ° C. or higher and 95 ° C. (peak) or lower while pulverizing the generated gel, and a hydrogel crosslinked polymer was taken out 42 minutes after the polymerization started. The obtained hydrogel crosslinked polymer was subdivided to have a diameter of about 5 mm or less. This finely divided hydrogel crosslinked polymer was spread on a 20 mesh (mesh 850 μm) wire mesh and dried with hot air at 180 ° C. for 40 minutes. Next, the mixture is pulverized using a roll mill and further classified and prepared with a JIS standard sieve having an opening of 600 μm, so that the ratio of the resin having a weight average particle size of 270 μm and a particle size of 500 μm or more and less than 600 μm is 0.2% by weight, The ratio of the resin having a particle diameter of less than 150 μm was 9.0% by weight, the logarithmic standard deviation (σζ) was 0.365, and the water content was 6% by weight. .
得られた吸水性樹脂粒子(L)の物性を測定したところ、CRC=45.0(g/g)、可溶分量は13.0重量%であった。 When the physical properties of the water-absorbent resin particles (L) obtained were measured, CRC = 45.0 (g / g) and the soluble content was 13.0% by weight.
該得られた吸水性樹脂粒子(L)500gを5Lレーディゲミキサー(M5R型レーディゲ社製)に入れ、該レーディゲミキサーの主軸(鋤状羽根)を330rpmで回転させながら、デナコール/1,4−ブタンジオール/プロピレングリコール/水=0.03/0.32/0.5/2.73重量%混合溶液17.9gをスプレーにより噴霧しながら投入し1分間混合した。その後撹拌を停止し、得られた混合物を速やかに取り出した。 500 g of the obtained water-absorbing resin particles (L) were put into a 5 L Ladige mixer (manufactured by M5R type Ladige), and while the main shaft (squilled blade) of the Ladige mixer was rotated at 330 rpm, Denacol / 1 , 4-butanediol / propylene glycol / water = 0.03 / 0.32 / 0.5 / 2.73 wt% mixed solution 17.9 g was added while spraying and mixed for 1 minute. Stirring was then stopped and the resulting mixture was quickly removed.
次に、得られた該混合物を、オイルバスにより容器を210℃に加熱された5Lモルタルミキサー(西日本試験機製作所製)に投入し、該混合物に均一に熱が加わるように撹拌混合した。約30分後、該モルタルミキサーより該混合物を取り出し、その全量を850μmのJIS標準篩を通過させ、表面処理された吸水性樹脂粒子(L)を得た。 Next, the obtained mixture was put into a 5 L mortar mixer (manufactured by West Japan Testing Machine Co., Ltd.) whose container was heated to 210 ° C. by an oil bath, and stirred and mixed so that heat was uniformly applied to the mixture. After about 30 minutes, the mixture was taken out from the mortar mixer, and the whole amount was passed through a 850 μm JIS standard sieve to obtain surface-treated water-absorbent resin particles (L).
表面処理された吸水性樹脂粒子(L)の物性を表3に示す。該表面処理された吸水性樹脂粒子(L)を、150μmのJIS標準篩で分級し、粒子径150μm以上の粒子(粗粒子(α))と粒子径150μm未満の粒子(微粉(β))に分割した。 Table 3 shows the physical properties of the surface-treated water-absorbent resin particles (L). The surface-treated water-absorbing resin particles (L) are classified with a 150 μm JIS standard sieve to form particles having a particle size of 150 μm or more (coarse particles (α)) and particles having a particle size of less than 150 μm (fine powder (β)). Divided.
(実施例1)
150μm通過の吸水性樹脂分級物(D)(4.8g)を600mlのプラスチック製容器(85mmφ×119mm)に入れ、脱イオン水(7.5g)を添加し30秒間スパチュラで混合した。脱イオン水を混合した150μm通過の吸水性樹脂分級物(D)に850μm通過150μm未通過の吸水性樹脂調合物(C)(45.2g)を添加し、さらに30秒間スパチュラで混合した。混合後すぐに混合物をシャーレ(145mmφ)上にひろげ、80℃の無風乾燥器で60分乾燥し、分級して850μm通過の粒子状吸水剤(1)を得た。
Example 1
The water-absorbent resin classification product (D) (4.8 g) passing through 150 μm was placed in a 600 ml plastic container (85 mmφ × 119 mm), deionized water (7.5 g) was added, and the mixture was mixed with a spatula for 30 seconds. The water absorbent resin preparation (C) (45.2 g) which did not pass 150 μm through 850 μm was added to the water absorbent resin classified product (D) which passed 150 μm mixed with deionized water, and further mixed with a spatula for 30 seconds. Immediately after mixing, the mixture was spread on a petri dish (145 mmφ), dried in an airless dryer at 80 ° C. for 60 minutes, and classified to obtain a particulate water-absorbing agent (1) passing through 850 μm.
(実施例2)
150μm通過の吸水性樹脂分級物(D)(4.8g)を600mlのプラスチック製容器(85mmφ×119mm)に入れ、脱イオン水(15g)を添加し30秒間スパチュラで混合した。脱イオン水を混合した150μm通過の吸水性樹脂分級物(D)に850μm通過150μm未通過の吸水性樹脂調合物(C)(45.2g)を添加し、さらに30秒間スパチュラで混合した。混合後すぐに混合物をシャーレ(145mmφ)上にひろげ、80℃の無風乾燥器で90分乾燥し、分級して850μm通過の粒子状吸水剤(2)を得た。
(Example 2)
The water-absorbing resin classification product (D) (4.8 g) passing through 150 μm was placed in a 600 ml plastic container (85 mmφ × 119 mm), deionized water (15 g) was added, and mixed with a spatula for 30 seconds. The water absorbent resin preparation (C) (45.2 g) which did not pass 150 μm through 850 μm was added to the water absorbent resin classified product (D) which passed 150 μm mixed with deionized water, and further mixed with a spatula for 30 seconds. Immediately after mixing, the mixture was spread on a petri dish (145 mmφ), dried in an airless dryer at 80 ° C. for 90 minutes, and classified to obtain a particulate water-absorbing agent (2) passing through 850 μm.
(実施例3)
150μm通過の吸水性樹脂分級物(D)(4.8g)を600mlのプラスチック製容器(85mmφ×119mm)に入れ、脱イオン水(2.5g)を添加し30秒間スパチュラで混合した。脱イオン水を混合した150μm通過の吸水性樹脂分級物(D)に850μm通過150μm未通過の吸水性樹脂調合物(C)(45.2g)を添加し、さらに30秒間スパチュラで混合した。混合後すぐに混合物をシャーレ(145mmφ)上にひろげ、80℃の無風乾燥器で30分乾燥し、分級して850μm通過の粒子状吸水剤(3)を得た。
(Example 3)
The water-absorbing resin classification product (D) (4.8 g) passing through 150 μm was placed in a 600 ml plastic container (85 mmφ × 119 mm), deionized water (2.5 g) was added, and mixed with a spatula for 30 seconds. The water absorbent resin preparation (C) (45.2 g) which did not pass 150 μm through 850 μm was added to the water absorbent resin classified product (D) which passed 150 μm mixed with deionized water, and further mixed with a spatula for 30 seconds. Immediately after mixing, the mixture was spread on a petri dish (145 mmφ), dried in an airless dryer at 80 ° C. for 30 minutes, and classified to obtain a particulate water-absorbing agent (3) passing through 850 μm.
(実施例4)
150μm通過の吸水性樹脂分級物(D)(15.0g)を600mlのプラスチック製容器(85mmφ×119mm)に入れ、脱イオン水(22.5g)を添加し30秒間スパチュラで混合した。脱イオン水を混合した150μm通過の吸水性樹脂分級物(D)に850μm通過150μm未通過の吸水性樹脂調合物(C)(35.0g)を添加し、さらに30秒間スパチュラで混合した。混合後すぐに混合物をシャーレ(145mmφ)上にひろげ、80℃の無風乾燥器で150分乾燥し、分級して850μm通過の粒子状吸水剤(4)を得た。
Example 4
The water absorbent resin classified product (D) (15.0 g) passing through 150 μm was placed in a 600 ml plastic container (85 mmφ × 119 mm), deionized water (22.5 g) was added, and the mixture was mixed with a spatula for 30 seconds. The water absorbent resin preparation (C) (35.0 g) which passed through 850 μm and did not pass 150 μm was added to the water absorbent resin classified product (D) which passed through 150 μm mixed with deionized water, and further mixed with a spatula for 30 seconds. Immediately after mixing, the mixture was spread on a petri dish (145 mmφ), dried in an airless dryer at 80 ° C. for 150 minutes, and classified to obtain a particulate water-absorbing agent (4) passing through 850 μm.
(実施例5)
150μm通過の吸水性樹脂分級物(G)(28.5g)を600mlのプラスチック製容器(85mmφ×119mm)に入れ、脱イオン水(45g)を添加し60秒間混合した。予め5Lレーディゲミキサー(M−5R型、レーディゲ社製)に850μm通過150μm未通過の吸水性樹脂分級物(F)(271.5g)を添加しておいたところに、脱イオン水を混合した150μm通過の吸水性樹脂分級物(G)を一気に投入し、撹拌翼を回転数330rpmで撹拌して10分間混合した。混合後すぐに混合物をシャーレ(145mmφ)上に広げ、80℃の無風乾燥器で60分乾燥し、分級して850μm通過の粒子状吸水剤(5)を得た。
(Example 5)
The water absorbent resin classified product (G) (28.5 g) passing through 150 μm was placed in a 600 ml plastic container (85 mmφ × 119 mm), and deionized water (45 g) was added and mixed for 60 seconds. Deionized water was mixed in a 5 L Leedige mixer (M-5R type, manufactured by Leedige) where 850 μm passed water absorbent resin classification (F) (271.5 g) that had not passed 150 μm was added. The 150 μm-passing water-absorbing resin classification product (G) was charged all at once, and the stirring blade was stirred at a rotation speed of 330 rpm and mixed for 10 minutes. Immediately after mixing, the mixture was spread on a petri dish (145 mmφ), dried in an airless dryer at 80 ° C. for 60 minutes, and classified to obtain a particulate water-absorbing agent (5) passing through 850 μm.
(実施例6)
150μm通過の吸水性樹脂分級物(J)(27.0g)を5Lプロシェアーミキサ(WB−5型、太平洋機工株式会社製)に入れ、脱イオン水(135g)を添加し撹拌翼を回転数330rpmで撹拌して1分間混合した。この混合物を撹拌しているところに850μm通過150μm未通過の吸水性樹脂分級物(I)(273.0g)を一気に投入し、さらに撹拌翼を回転数330rpmで撹拌して1分間混合した。混合後すぐに混合物を目開き38μmの金網上にひろげて80℃の熱風乾燥器で25分乾燥し、分級して850μm通過の粒子状吸水剤(6)を得た。
(Example 6)
150 μm passing water absorbent resin classification (J) (27.0 g) is put into a 5 L pro-shear mixer (WB-5 type, manufactured by Taiheiyo Kiko Co., Ltd.), deionized water (135 g) is added, and the stirring blade is rotated at a rotational speed. Stir at 330 rpm and mix for 1 minute. While the mixture was being stirred, the water-absorbent resin classification product (I) (273.0 g) that passed through 850 μm but did not pass through 150 μm was charged all at once, and the stirring blade was further stirred at a rotation speed of 330 rpm and mixed for 1 minute. Immediately after mixing, the mixture was spread on a wire mesh with an opening of 38 μm, dried in a hot air dryer at 80 ° C. for 25 minutes, and classified to obtain a particulate water-absorbing agent (6) passing through 850 μm.
(実施例7)
150μm通過の吸水性樹脂分級物(I)(27.0g)を5Lプロシェアーミキサ(WB−5型、太平洋機工株式会社製)に入れ、脱イオン水(45g)を添加し撹拌翼を回転数330rpmで撹拌して10分間混合した。この混合物を撹拌しているところに850μm通過150μm未通過の吸水性樹脂分級物(I)(273.0g)を一気に投入し、さらに撹拌翼を回転数330rpmで撹拌して5分間混合した。混合後すぐに混合物を目開き38μmの金網上に広げて80℃の熱風乾燥器で10分乾燥し、分級して850μm通過の粒子状吸水剤(7)を得た。
(Example 7)
A 150 μm-passage water-absorbent resin classification product (I) (27.0 g) is placed in a 5 L pro-shear mixer (WB-5 type, manufactured by Taiheiyo Kiko Co., Ltd.), deionized water (45 g) is added, and the stirring blade is rotated at a rotational speed. Stir at 330 rpm and mix for 10 minutes. While this mixture was being stirred, the water-absorbent resin classification product (I) (273.0 g) that passed 850 μm but not 150 μm was charged all at once, and the stirring blade was further stirred at a rotation speed of 330 rpm and mixed for 5 minutes. Immediately after mixing, the mixture was spread on a wire mesh with an opening of 38 μm, dried for 10 minutes with a hot air dryer at 80 ° C., and classified to obtain a particulate water-absorbing agent (7) that passed through 850 μm.
(実施例8)
150μm通過の吸水性樹脂分級物(J)(27.0g)を5Lプロシェアーミキサ(WB−5型、太平洋機工株式会社製)に入れ、脱イオン水(30g)を添加し撹拌翼を回転数330rpmで撹拌して10分間混合した。この混合物を撹拌しているところに850μm通過150μm未通過の吸水性樹脂分級物(I)(273.0g)を一気に投入し、さらに撹拌翼を回転数330rpmで撹拌して10分間混合した。混合後すぐに混合物を目開き38μmの金網上にひろげて80℃の熱風乾燥器で10分乾燥し、分級して850μm通過の粒子状吸水剤(8)を得た。
(Example 8)
A 150 μm-passage water-absorbent resin classification product (J) (27.0 g) is placed in a 5 L pro-shear mixer (WB-5 type, manufactured by Taiheiyo Kiko Co., Ltd.), deionized water (30 g) is added, and the stirring blade is rotated at a rotational speed. Stir at 330 rpm and mix for 10 minutes. While this mixture was being stirred, the water-absorbent resin classification product (I) (273.0 g) that passed 850 μm but not 150 μm was added all at once, and the stirring blade was further stirred at a rotation speed of 330 rpm and mixed for 10 minutes. Immediately after mixing, the mixture was spread on a wire mesh having a mesh opening of 38 μm, dried with a hot air dryer at 80 ° C. for 10 minutes, and classified to obtain a particulate water-absorbing agent (8) passing through 850 μm.
(実施例9)
製造例4で得られた、表面処理された吸水性樹脂粒子(K)500gを5Lレーディゲミキサー(M5R型レーディゲ社製)に入れ、該レーディゲミキサーの主軸(鋤状羽根)を330rpmで回転させながら、水50gをスプレー噴霧により投入し、1分間混合することにより、吸水性樹脂含水物を得た(水性液を添加する工程)。
Example 9
500 g of the surface-treated water-absorbent resin particles (K) obtained in Production Example 4 were placed in a 5 L Ladige mixer (manufactured by M5R type Ladige), and the main shaft (squid-shaped blade) of the Ladige mixer was set at 330 rpm. While rotating at 50 ° C., 50 g of water was added by spraying and mixed for 1 minute to obtain a water-absorbing resin hydrated product (step of adding an aqueous liquid).
混合後直ちに、水不溶性無機微粒子(Aerosil200:Aerosil社製)1.5gをレーディゲミキサーでの撹拌下において添加し、更に30秒間(凝集体が分散状態になるまで)混合(微粒子混合工程)を行うことで吸水性樹脂含水組成物(9)を得た。 Immediately after mixing, 1.5 g of water-insoluble inorganic fine particles (Aerosil 200: manufactured by Aerosil) are added under stirring with a Laedige mixer, and further mixed for 30 seconds (until the aggregates are dispersed) (fine particle mixing step) To obtain a water-absorbing resin water-containing composition (9).
得られた吸水性樹脂含水組成物(9)は流動性を有しており、その流下速度を(JIS K3362の測定装置を用いた)測定したところ、21秒/100gであった。得られた吸水性樹脂含水組成物(9)を密閉容器に移し、60℃の無風乾燥機中で1時間静置することにより、硬化(吸水性樹脂内部へ添加した水分を吸収させる)を行った。1時間加熱後、乾燥機から硬化した吸水性樹脂造粒物(IX)を取り出した。硬化した吸水性樹脂造粒物(IX)も流動性を有しており、その流下速度は、18秒/100gであった。 The water-absorbing resin water-containing composition (9) thus obtained had fluidity, and its flow rate (measured using a measuring device of JIS K3362) was measured and found to be 21 seconds / 100 g. The obtained water-absorbing resin water-containing composition (9) is transferred to a sealed container and left to stand in a windless dryer at 60 ° C. for 1 hour to cure (absorb water added to the water-absorbing resin). It was. After heating for 1 hour, the cured water absorbent resin granulated product (IX) was taken out from the dryer. The cured water-absorbent resin granulated product (IX) also has fluidity, and the flow rate was 18 seconds / 100 g.
吸水性樹脂造粒物(IX)にプロセスダメージ(ペイントシェーカー(P/S):SAP/ガラスビーズ/振盪時間=30g/10g/10分)を与え、粒度分布、CRC、AAP1.9kPa、AAP4.8kPa、Vortex、流下速度、嵩比重、含水率、無機微粒子含有量などの物性を測定した。結果を表3に示す。 Process damage (Paint shaker (P / S): SAP / glass beads / shaking time = 30 g / 10 g / 10 min) was given to the water absorbent resin granulated product (IX), particle size distribution, CRC, AAP 1.9 kPa, AAP 4. Physical properties such as 8 kPa, Vortex, flow velocity, bulk specific gravity, moisture content, inorganic fine particle content were measured. The results are shown in Table 3.
(実施例10)
実施例9における添加水量を250gに変更した以外は、全て実施例9と同様に行った。得られた吸水性樹脂造粒物(X)を実施例9と同様に評価し、結果を表3にまとめた。
(Example 10)
All operations were performed in the same manner as in Example 9, except that the amount of water added in Example 9 was changed to 250 g. The obtained water absorbent resin granulated product (X) was evaluated in the same manner as in Example 9, and the results are summarized in Table 3.
(実施例11)
製造例5で得られた、表面処理された微粉(β)45gを5Lレーディゲミキサー(M5R型レーディゲ社製)に入れ、該レーディゲミキサーの主軸(鋤状羽根)を330rpmで回転させながら、水25gを一気に投入し1分間混合することにより、微粉含水ゲルを得た(水性液混合工程)。
(Example 11)
45 g of the surface-treated fine powder (β) obtained in Production Example 5 was placed in a 5 L Ladige mixer (manufactured by M5R type Ladige), and the main shaft of the Ladige mixer (squilled blade) was rotated at 330 rpm. However, by adding 25 g of water all at once and mixing for 1 minute, a finely hydrated gel was obtained (aqueous liquid mixing step).
混合後直ちに、更に、表面処理された粗粒子(α)455gを、得られた上記微粉含水ゲルにレーディゲミキサーでの撹拌下において添加し、更に1分間混合した(水性液混合工程)。更に、粗粒の混合後、直ちに水不溶性無機微粒子(Aerosil200:Aerosil社製)1.5gをレーディゲミキサーでの撹拌下において添加し、更に30秒間(凝集体が分散状態になるまで)混合(微粒子混合工程)を行うことで吸水性樹脂含水組成物(11)を得た。 Immediately after mixing, 455 g of the surface-treated coarse particles (α) was further added to the obtained finely powdered water-containing gel under stirring with a Roedige mixer and further mixed for 1 minute (aqueous liquid mixing step). Further, immediately after mixing the coarse particles, 1.5 g of water-insoluble inorganic fine particles (Aerosil 200: manufactured by Aerosil) are added under stirring with a Roedige mixer, and further mixed for 30 seconds (until the aggregates are dispersed). The water-absorbing resin water-containing composition (11) was obtained by performing (fine particle mixing step).
得られた吸水性樹脂含水組成物(11)は流動性を有しており、その流下速度(JIS K3362の測定装置を用いた)を測定したところ、20秒/100gであった。得られた吸水性樹脂含水組成物(11)を密閉容器に移し、60℃を有する無風乾燥機中で1時間静置することにより、硬化(吸水性樹脂内部へ添加した水分を吸収させる)を行った。1時間後、乾燥機から硬化した吸水性樹脂造粒物(XI)を取り出した。硬化した吸水性樹脂造粒物(XI)も流動性を有しており、その流下速度は、12秒/100gであった。吸水性樹脂造粒物(XI)にプロセスダメージ(ペイントシェーカー(P/S):SAP/ガラスビーズ/振盪時間=30g/10g/10分)を与え、粒度分布、CRC、AAP1.9kPa、AAP4.8kPa、Vortex、流下速度、嵩比重、含水率、無機微粒子含有量などの物性を測定した。結果を表3に示す。 The obtained water-absorbing resin water-containing composition (11) had fluidity, and its flow rate (using a measuring device of JIS K3362) was measured and found to be 20 seconds / 100 g. The obtained water-absorbing resin water-containing composition (11) is transferred to a hermetically sealed container and left to stand in an airless dryer having a temperature of 60 ° C. for 1 hour to cure (absorb water added to the water-absorbing resin). went. After 1 hour, the cured water absorbent resin granulated product (XI) was taken out from the dryer. The cured water absorbent resin granulated product (XI) also has fluidity, and the flow-down speed was 12 seconds / 100 g. Process damage (Paint shaker (P / S): SAP / glass beads / shaking time = 30 g / 10 g / 10 min) was given to the water absorbent resin granulated product (XI), particle size distribution, CRC, AAP 1.9 kPa, AAP 4. Physical properties such as 8 kPa, Vortex, flow velocity, bulk specific gravity, moisture content, inorganic fine particle content were measured. The results are shown in Table 3.
(実施例12)
実施例11における添加水量を50gに変更した以外は、全て実施例11と同様に行った。得られた吸水性樹脂造粒物(XII)を実施例11と同様に評価し、結果を表3にまとめた。
(Example 12)
All of the procedures were performed in the same manner as in Example 11 except that the amount of added water in Example 11 was changed to 50 g. The obtained water absorbent resin granulated product (XII) was evaluated in the same manner as in Example 11, and the results are summarized in Table 3.
(実施例13)
実施例11における添加水量を75g、Aerosil200添加量を5gに変化した以外は、全て実施例11と同様に行った。得られた吸水性樹脂造粒物(XIII)を実施例11と同様に評価し、結果を表4にまとめた。
(Example 13)
The procedure of Example 11 was repeated except that the amount of water added in Example 11 was changed to 75 g and the amount of Aerosil 200 added was changed to 5 g. The obtained water absorbent resin granulated product (XIII) was evaluated in the same manner as in Example 11, and the results are summarized in Table 4.
(実施例14)
実施例13における硬化工程および/または乾燥工程を、開放系の容器(SUS製容器(外寸法296mm×231mm×49mm、底寸法250mm×185mm))を用いて、80℃を有する無風乾燥機中で60分静置に変更した以外は、全て実施例13と同様に行った。得られた吸水性樹脂造粒物(XIV)を実施例3と同様に評価し、結果を表4にまとめた。
(Example 14)
The curing step and / or the drying step in Example 13 were carried out in an airless dryer having a temperature of 80 ° C. using an open container (SUS container (outer dimensions: 296 mm × 231 mm × 49 mm, bottom dimension: 250 mm × 185 mm)). All were performed in the same manner as in Example 13 except for changing to stationary for 60 minutes. The obtained water absorbent resin granulated product (XIV) was evaluated in the same manner as in Example 3, and the results are summarized in Table 4.
(実施例15)
実施例13における硬化工程および/または乾燥工程を、開放系の容器(SUS製容器(外寸法296mm×231mm×49mm、底寸法250mm×185mm))を用いて、150℃を有する無風乾燥機中で60分静置に変更した以外は、全て実施例13と同様に行った。得られた吸水性樹脂造粒物(XV)を実施例11と同様に評価し、結果を表4にまとめた。
(Example 15)
The curing step and / or the drying step in Example 13 were carried out in an airless dryer having a temperature of 150 ° C. using an open container (SUS container (outer dimensions: 296 mm × 231 mm × 49 mm, bottom dimension: 250 mm × 185 mm)). All were performed in the same manner as in Example 13 except for changing to stationary for 60 minutes. The obtained water absorbent resin granulated product (XV) was evaluated in the same manner as in Example 11, and the results are summarized in Table 4.
(実施例16)
実施例11における添加水量を50gに変更し、Aerosil200と同時に、JIS標準篩で45μm未満の粒子径を有する竹表皮粉末を2.5g添加した以外は、全て実施例11と同様に行った。得られた吸水性樹脂造粒物(XVI)を実施例11と同様に評価し、結果を表4にまとめた。
(Example 16)
The amount of water added in Example 11 was changed to 50 g, and everything was the same as Example 11 except that 2.5 g of bamboo skin powder having a particle size of less than 45 μm was added with Aerosil 200 at the same time as Aerosil 200. The obtained water absorbent resin granulated product (XVI) was evaluated in the same manner as in Example 11, and the results are summarized in Table 4.
(実施例17)
実施例11における添加水量を50gに変更し、Aerosil200の替わりに、溶性デンプンを5g添加した以外は、全て実施例11と同様に行った。得られた吸水性樹脂造粒物(XVII)を実施例11と同様に評価し、結果を表4にまとめた。
(Example 17)
The procedure was the same as in Example 11 except that the amount of water added in Example 11 was changed to 50 g and that 5 g of soluble starch was added instead of Aerosil 200. The obtained water absorbent resin granulated product (XVII) was evaluated in the same manner as in Example 11, and the results are summarized in Table 4.
(実施例18)
実施例11における添加水量を50gに変更し、Aerosil200の替わりに、CARPLEX22S(カープレックス)(シオノギ製薬製)を1.5g添加した以外は、全て実施例11と同様に行った。得られた吸水性樹脂造粒物(XVIII)を実施例11と同様に評価し、結果を表5にまとめた。
(Example 18)
The same procedure as in Example 11 was performed except that the amount of water added in Example 11 was changed to 50 g and 1.5 g of CARPLEX 22S (Carplex) (manufactured by Shionogi Pharmaceutical Co., Ltd.) was added instead of Aerosil 200. The obtained water absorbent resin granulated product (XVIII) was evaluated in the same manner as in Example 11, and the results are summarized in Table 5.
(実施例19)
実施例9における吸水性樹脂粒子(K)を200g、添加水量を400g、Aerosil200添加量を20gに変更した以外は、全て実施例9と同様に行った。しかし、得られた吸水性樹脂含水組成物は、十分に硬化しないため、乾燥が必要であった。該吸水性樹脂含水組成物を150℃にて30分間静置乾燥することにより、吸水性樹脂造粒物(XIX)を得た。吸水性樹脂造粒物(XIX)を実施例9と同様に評価し、結果を表5に示した。本条件では、流動性を有した吸水性樹脂造粒物を得ることができるが、乾燥工程を必要とするため、好ましくは添加水量を減らした方が、エネルギーコストの面で有利である。
(Example 19)
The same procedure as in Example 9 was carried out except that the water-absorbent resin particles (K) in Example 9 were changed to 200 g, the amount of added water was changed to 400 g, and the amount of Aerosil 200 added was changed to 20 g. However, since the obtained water-absorbing resin water-containing composition is not sufficiently cured, it must be dried. The water-absorbent resin water-containing composition was allowed to stand and dry at 150 ° C. for 30 minutes to obtain a water-absorbent resin granulated product (XIX). The water absorbent resin granulated product (XIX) was evaluated in the same manner as in Example 9, and the results are shown in Table 5. Under these conditions, a water-absorbent resin granulated product having fluidity can be obtained. However, since a drying step is required, it is advantageous in terms of energy cost to reduce the amount of added water.
(実施例20)
実施例11における水の代わりに、3重量%水溶液コロイダルシリカ(HS−30(アルドリッチ製)を純粋で10倍に希釈)に変更し、Aerosil200添加を施さず、吸水性樹脂造粒物(XX)を得た。得られた吸水性樹脂造粒物(XX)を実施例11と同様に評価し、結果を表5に示した。
(Example 20)
Instead of water in Example 11, 3% by weight aqueous colloidal silica (HS-30 (manufactured by Aldrich) was changed to pure and diluted 10-fold), Aerosil 200 was not added, and water-absorbent resin granulated product (XX) Got. The obtained water absorbent resin granulated product (XX) was evaluated in the same manner as in Example 11, and the results are shown in Table 5.
(実施例21)
実施例11において、Aerosil添加を施さず、吸水性樹脂造粒物(XXI)とし、実施例10と同様に評価し、結果を表5に示した。
(Example 21)
In Example 11, Aerosil addition was not performed, and a water-absorbent resin granulated product (XXI) was evaluated in the same manner as in Example 10. The results are shown in Table 5.
(実施例22)
実施例12において、Aerosil添加を施さず、吸水性樹脂造粒物(XXII)とし、実施例10と同様に評価し、結果を表6に示した。
(Example 22)
In Example 12, Aerosil addition was not performed, and a water-absorbent resin granulated product (XXII) was evaluated in the same manner as in Example 10. The results are shown in Table 6.
(実施例23)
実施例13において、Aerosil添加を施さず、吸水性樹脂造粒物(XXIII)を作成したが、硬化しなかったため、乾燥が必要であった。そこで、該吸水性樹脂含水組成物を150℃にて30分間静置、乾燥することにより、吸水性樹脂造粒物(XXIII)を得た。得られた吸水性樹脂造粒物(XXIII)を実施例10と同様に評価し、結果を表6に示した。
(Example 23)
In Example 13, Aerosil addition was not performed, and a water-absorbent resin granulated product (XXIII) was prepared. However, since it was not cured, drying was necessary. Therefore, the water-absorbent resin water-containing composition was allowed to stand at 150 ° C. for 30 minutes and dried to obtain a water-absorbent resin granulated product (XXIII). The obtained water absorbent resin granulated product (XXIII) was evaluated in the same manner as in Example 10, and the results are shown in Table 6.
(実施例24)
実施例12において、Aerosil200の添加(1.5g)を、微粉含水ゲルに添加し、次いで粗粒を添加・混合し、吸水性樹脂造粒物(XXIV)を得た。得られた吸水性樹脂造粒物(XXIV)を実施例2と同様に評価し、結果を表6に示した。
(Example 24)
In Example 12, the addition of Aerosil 200 (1.5 g) was added to the finely divided water-containing gel, and then the coarse particles were added and mixed to obtain a water absorbent resin granulated product (XXIV). The obtained water absorbent resin granulated product (XXIV) was evaluated in the same manner as in Example 2, and the results are shown in Table 6.
(比較例1)
850μm通過150μm未通過の吸水性樹脂調合物(C)(45.2g)と150μm通過の吸水性樹脂分級物(D)(4.8g)を600mlのプラスチック製容器(85mmφ×119mm)に入れ混合し、そこに脱イオン水(7.5g)を添加し30秒間スパチュラで混合した。混合後すぐに混合物をシャーレ(145mmφ)上にひろげ、80℃の無風乾燥器で60分乾燥し、分級して850μm通過の比較粒子状吸水剤(1)を得た。
(Comparative Example 1)
The water absorbent resin formulation (C) (45.2 g) that passed 850 μm and not passed 150 μm and the water absorbent resin classification (D) (4.8 g) that passed 150 μm were placed in a 600 ml plastic container (85 mmφ × 119 mm) and mixed. Then, deionized water (7.5 g) was added thereto and mixed with a spatula for 30 seconds. Immediately after mixing, the mixture was spread on a petri dish (145 mmφ), dried in an airless dryer at 80 ° C. for 60 minutes, and classified to obtain a comparative particulate water-absorbing agent (1) that passed through 850 μm.
(比較例2)
850μm通過150μm未通過の吸水性樹脂調合物(C)(45.2g)と150μm通過の吸水性樹脂分級物(D)(4.8g)を600mlのプラスチック製容器(85mmφ×119mm)に入れ混合し、そこに脱イオン水(2.5g)を添加し30秒間スパチュラで混合した。混合後すぐに混合物をシャーレ(145mmφ)上にひろげ、80℃の無風乾燥器で30分乾燥し、分級して850μm通過の比較粒子状吸水剤(2)を得た。
(Comparative Example 2)
The water absorbent resin formulation (C) (45.2 g) that passed 850 μm and not passed 150 μm and the water absorbent resin classification (D) (4.8 g) that passed 150 μm were placed in a 600 ml plastic container (85 mmφ × 119 mm) and mixed. Then, deionized water (2.5 g) was added thereto and mixed with a spatula for 30 seconds. Immediately after mixing, the mixture was spread on a petri dish (145 mmφ), dried in an airless dryer at 80 ° C. for 30 minutes, and classified to obtain a comparative particulate water-absorbing agent (2) that passed through 850 μm.
(比較例3)
150μm通過の吸水性樹脂分級物(G)(28.5g)と850μm通過150μm未通過の吸水性樹脂分級物(F)(271.5g)を5Lレーディゲミキサー(M−5R型、レーディゲ社製)に入れ、撹拌翼回転数330rpmで撹拌させると同時に、脱イオン水(45g)を添加し10分間混合した。混合後すぐに混合物をシャーレ(145mmφ)上にひろげ80℃の無風乾燥器で60分乾燥し、分級して850μm通過の比較粒子状吸水剤(3)を得た。
(Comparative Example 3)
Water absorbent resin classification (G) (28.5 g) passing through 150 μm and water absorbent resin classification (F) (271.5 g) passing through 850 μm but not 150 μm were mixed with a 5 L-Radige mixer (M-5R type, Redige) In addition, deionized water (45 g) was simultaneously added and mixed for 10 minutes. Immediately after mixing, the mixture was spread on a petri dish (145 mmφ), dried with an airless dryer at 80 ° C. for 60 minutes, and classified to obtain a comparative particulate water-absorbing agent (3) passing through 850 μm.
(比較例4)
150μm通過の吸水性樹脂分級物(G)(28.5g)と850μm通過150μm未通過の吸水性樹脂分級物(F)(271.5g)を5Lレーディゲミキサー(M−5R型、レーディゲ社製)に入れ、撹拌翼回転数330rpmで撹拌させると同時に、脱イオン水(90g)を添加し10分間混合した。混合物は直径1cm以上の塊が多く存在した。混合後すぐに混合物をシャーレ(145mmφ)上にひろげ80℃の無風乾燥器で60分乾燥した。乾燥物には直径1cm以上の硬い塊が多く存在して、分級して850μm通過の比較粒子状吸水剤(4)は殆ど得られず、良好な造粒は出来なかった。
(Comparative Example 4)
Water absorbent resin classification (G) (28.5 g) passing through 150 μm and water absorbent resin classification (F) (271.5 g) passing through 850 μm but not 150 μm were mixed with a 5 L-Radige mixer (M-5R type, Redige) The mixture was stirred at a stirring blade speed of 330 rpm, and deionized water (90 g) was added and mixed for 10 minutes. The mixture had many lumps having a diameter of 1 cm or more. Immediately after mixing, the mixture was spread on a petri dish (145 mmφ) and dried in an airless dryer at 80 ° C. for 60 minutes. There were many hard lumps having a diameter of 1 cm or more in the dried product, and the comparative particulate water-absorbing agent (4) passing through 850 μm was hardly obtained, and good granulation could not be performed.
(比較例5)
実施例9において、Aerosil添加を施さず、比較吸水性樹脂造粒物(5)とし、実施例9と同様に評価した。
(Comparative Example 5)
In Example 9, Aerosil addition was not performed, and a comparative water absorbent resin granulated product (5) was obtained and evaluated in the same manner as in Example 9.
(試験例)
粒子状吸水剤(1)〜(8)と比較粒子状吸水剤(1)〜(4)の重量平均粒子径、微粉末割合、無加圧下吸収倍率、加圧下吸収倍率、含水率の測定および耐衝撃テストをおこなった。結果を表1〜7に示す。
(Test example)
Measurement of the weight average particle diameter, fine powder ratio, absorption ratio under no pressure, absorption capacity under pressure, moisture content of the particulate water absorbing agent (1) to (8) and the comparative particulate water absorbing agent (1) to (4) An impact resistance test was performed. The results are shown in Tables 1-7.
同じ水性液の添加量で比較して、第一の吸水性樹脂粉末(吸水性樹脂分級物(D))と第二の吸水性樹脂粉末(吸水性樹脂調合物(C))を予め混合したところに水性液を混合(一括造粒)した比較粒子状吸水剤(1)(微粉末量6.0重量%)に比べて、本発明の粒子状吸水剤(1)(微粉末量3.6重量%)では微粉末量が大きく改善された。また、一括造粒した比較粒子状吸水剤(2)(微粉末量9.6重量%)に比べて、本発明の粒子状吸水剤(3)(微粉末量7.3重量%)では微粉末量が大きく改善されている。また、粒子状吸水剤(1)〜(3)で水性液の添加量が多いほど、微粉末量が改善されている。また、粒子状吸収剤(4)では水添加量が45重量部と多く、さらに、第一の吸水性樹脂粉末と第二の吸水性樹脂粉末の重量比が30/70と微粉末の割合が多い場合でも、微粉末量は大きく減少できた。 The first water-absorbent resin powder (water-absorbent resin classification (D)) and the second water-absorbent resin powder (water-absorbent resin formulation (C)) were mixed in advance by comparison with the same amount of aqueous liquid added. However, compared with the comparative particulate water-absorbing agent (1) (fine powder amount 6.0 wt%) mixed with an aqueous liquid (collective granulation), the particulate water-absorbing agent (1) of the present invention (fine powder amount 3. 6% by weight), the amount of fine powder was greatly improved. In addition, the particulate water-absorbing agent (3) of the present invention (fine powder amount 7.3 wt%) is finer than the batch-granulated comparative particulate water-absorbing agent (2) (fine powder amount 9.6 wt%). The amount of powder is greatly improved. Moreover, the amount of fine powder is improved, so that there is much addition amount of an aqueous liquid in particulate water absorbing agent (1)-(3). In the particulate absorbent (4), the amount of water added is as large as 45 parts by weight, and the weight ratio of the first water-absorbent resin powder to the second water-absorbent resin powder is 30/70, and the proportion of fine powder is as follows. Even when the amount was large, the amount of fine powder could be greatly reduced.
同じ水性液の添加量(15重量部)で比較して、一括造粒した比較粒子状吸水剤(3)(衝撃前の微粉末量1.9重量%、衝撃後4.9重量%)に比べて、本発明の粒子状吸水剤(5)(衝撃前の微粉末量0.5重量%、衝撃後1.5重量%)では微粉末量が大きく改善されている。30重量部という多量の水性液を添加して一括造粒した比較粒子状吸水剤(4)では直径1cm以上の塊ができて造粒不能であったが、本発明の粒子状吸水剤(6)では45重量部という多量の水性液を均一に混合でき、より造粒強度を高めることができた。 Compared with the same amount of aqueous liquid added (15 parts by weight), the granulated comparative particulate water-absorbing agent (3) (the amount of fine powder before impact 1.9% by weight, after impact 4.9% by weight) Compared with the particulate water-absorbing agent (5) of the present invention (the amount of fine powder before impact is 0.5% by weight, the amount after impact is 1.5% by weight), the amount of fine powder is greatly improved. In the comparative particulate water-absorbing agent (4) which was granulated at once by adding a large amount of aqueous liquid of 30 parts by weight, a lump with a diameter of 1 cm or more was formed and granulation was impossible. However, the particulate water-absorbing agent (6 ), A large amount of an aqueous liquid of 45 parts by weight could be uniformly mixed, and the granulation strength could be further increased.
本発明は上述した各実施形態に限定されるものではなく、請求項に示した範囲で種々の変更が可能であり、異なる実施形態にそれぞれ開示された技術的手段を適宜組み合わせて得られる実施形態についても本発明の技術的範囲に含まれる。 The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.
以上のように、本発明では、少なくとも吸水性樹脂粒子と水性液とを混合し、さらに吸水性樹脂含水物に吸水性樹脂または吸水性樹脂以外の微粒子微粒子を混合するため、高い造粒強度を有する上、造粒による物性低下も小さい、微粉末量が非常に低減された粒子状吸水剤を得ることができる。 As described above, in the present invention, at least the water-absorbent resin particles and the aqueous liquid are mixed, and further, the water-absorbent resin water-containing product is mixed with the water-absorbent resin or fine particles other than the water-absorbent resin. In addition, it is possible to obtain a particulate water-absorbing agent in which the amount of fine powder is greatly reduced, and the physical property deterioration due to granulation is small.
また、吸水性樹脂含水物の塊状化を防止し、低温・短時間で吸水性樹脂含水組成物の硬化等を行うことができる。その結果、高含水率(5重量%以上20重量%以下)でプロセスダメージにも強く、非常に効率的に吸水性樹脂造粒物を製造することができる。 In addition, the water-absorbing resin water-containing composition can be prevented from being agglomerated and the water-absorbing resin water-containing composition can be cured at a low temperature and in a short time. As a result, the water-absorbent resin granulated product can be produced very efficiently with a high water content (5 wt% or more and 20 wt% or less) and strong process damage.
そのため、本発明は、吸水性樹脂造粒物を使用する製品に関する分野、具体的には生理用品、オムツ、土壌改良剤などの製造に関する分野において応用が可能である。 Therefore, the present invention can be applied in the field relating to products using the water-absorbent resin granulated product, specifically in the field relating to the manufacture of sanitary products, diapers, soil improvers and the like.
Claims (10)
該吸水性樹脂含水物に、重量平均粒子径が200〜800μmである第二の吸水性樹脂粒子を混合する工程(b)とを含む吸水性樹脂造粒物の製造方法。 A step (a) of obtaining a water-absorbent resin hydrate by mixing the first water-absorbent resin particles having a weight average particle diameter of less than 200 μm and an aqueous liquid;
Method for producing a water-absorbent resin hydrate, weight average particle diameter of the water-absorbent resin granulation product and a step (b) mixing the second water-absorbing resin particles child is 200~800Myuemu.
水分を吸水性樹脂造粒物の全量100重量部に対して5重量部以上20重量部以下、含み、
(1)0.90重量%の塩化ナトリウム水溶液に対する無加圧下吸収倍率が27g/g以上であり、
(2)0.90重量%の塩化ナトリウム水溶液に対する1.9kPaでの加圧下吸収倍率が20g/g以上であり、
(3)0.90重量%の塩化ナトリウム水溶液に対する4.8kPaでの加圧下吸収倍率が10g/g以上であり、
(4)0.90重量%の塩化ナトリウム水溶液に対する吸収速度が20秒以上50秒以下であり、
(5)吸水性樹脂造粒物100重量部に対し、目開き150μmのJIS標準篩を通過する粒子が0重量部以上5重量部以下であることを特徴とする吸水性樹脂造粒物。 A water absorbent resin granulated product obtained by the method for producing a water absorbent resin granulated product according to any one of claims 1 to 9,
20 parts by weight or less in 5 parts by weight or more relative to the total amount 100 parts by weight of the water-absorbent resin granulation product moisture, seen including,
(1) Absorption capacity under no pressure with respect to 0.90% by weight sodium chloride aqueous solution is 27 g / g or more,
(2) Absorption capacity under pressure at 1.9 kPa with respect to 0.90 wt% sodium chloride aqueous solution is 20 g / g or more,
(3) Absorption capacity under pressure at 4.8 kPa with respect to 0.90% by weight sodium chloride aqueous solution is 10 g / g or more,
(4) The absorption rate for a 0.90% by weight sodium chloride aqueous solution is 20 seconds to 50 seconds,
(5) A water-absorbent resin granulated product, wherein particles passing through a JIS standard sieve having an opening of 150 μm are 0 to 5 parts by weight with respect to 100 parts by weight of the water-absorbent resin granulated product.
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JPS57117551A (en) * | 1981-01-10 | 1982-07-22 | Seitetsu Kagaku Co Ltd | Powdering of acrylate polymer |
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DE3741158A1 (en) * | 1987-12-04 | 1989-06-15 | Stockhausen Chem Fab Gmbh | POLYMERISATES WITH HIGH ABSORPTION SPEED FOR WATER AND AQUEOUS LIQUIDS, METHOD FOR THE PRODUCTION THEREOF AND USE AS ABSORBENTS |
JPH08113653A (en) * | 1994-10-17 | 1996-05-07 | Mitsubishi Chem Corp | Granulation of highly water-absorbing resin powder |
JPH08253597A (en) * | 1995-03-15 | 1996-10-01 | Nippon Synthetic Chem Ind Co Ltd:The | Method for granulating highly water-absorptive resin |
JP3494401B2 (en) * | 1998-09-22 | 2004-02-09 | 株式会社日本触媒 | Water absorbent and absorbent articles |
JP4132592B2 (en) * | 1999-06-25 | 2008-08-13 | 株式会社日本触媒 | Water absorbent resin and method for producing the same |
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US9975979B2 (en) | 2014-10-08 | 2018-05-22 | Lg Chem, Ltd. | Method of preparing superabsorbent polymer |
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