JP2023069002A - Method for producing nonwoven fabric - Google Patents
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- 239000004745 nonwoven fabric Substances 0.000 title claims abstract description 67
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 24
- 239000000835 fiber Substances 0.000 claims abstract description 45
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 36
- 239000010954 inorganic particle Substances 0.000 claims abstract description 31
- 239000000470 constituent Substances 0.000 claims abstract description 16
- 239000003960 organic solvent Substances 0.000 claims abstract description 10
- 239000004094 surface-active agent Substances 0.000 claims abstract description 9
- 238000000034 method Methods 0.000 claims description 43
- 239000002245 particle Substances 0.000 claims description 26
- 229920005672 polyolefin resin Polymers 0.000 claims description 5
- 239000000463 material Substances 0.000 description 12
- 229920005989 resin Polymers 0.000 description 9
- 239000011347 resin Substances 0.000 description 9
- 238000002347 injection Methods 0.000 description 8
- 239000007924 injection Substances 0.000 description 8
- 239000007788 liquid Substances 0.000 description 7
- 238000005406 washing Methods 0.000 description 7
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 6
- 238000001035 drying Methods 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- 238000004140 cleaning Methods 0.000 description 5
- 230000035699 permeability Effects 0.000 description 5
- 238000009987 spinning Methods 0.000 description 5
- 230000000052 comparative effect Effects 0.000 description 4
- 238000007602 hot air drying Methods 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- 239000003795 chemical substances by application Substances 0.000 description 3
- 230000002209 hydrophobic effect Effects 0.000 description 3
- 239000010410 layer Substances 0.000 description 3
- 230000003287 optical effect Effects 0.000 description 3
- 239000002243 precursor Substances 0.000 description 3
- 230000000717 retained effect Effects 0.000 description 3
- 229920001169 thermoplastic Polymers 0.000 description 3
- 239000004416 thermosoftening plastic Substances 0.000 description 3
- 239000011787 zinc oxide Substances 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical group [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 239000004743 Polypropylene Substances 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 125000003118 aryl group Chemical group 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 230000001877 deodorizing effect Effects 0.000 description 2
- 238000001523 electrospinning Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 239000012528 membrane Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000013618 particulate matter Substances 0.000 description 2
- 239000004033 plastic Substances 0.000 description 2
- 229920003023 plastic Polymers 0.000 description 2
- 229920001225 polyester resin Polymers 0.000 description 2
- 239000004645 polyester resin Substances 0.000 description 2
- -1 polypropylene Polymers 0.000 description 2
- 229920001155 polypropylene Polymers 0.000 description 2
- 239000011164 primary particle Substances 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 238000001223 reverse osmosis Methods 0.000 description 2
- 239000011163 secondary particle Substances 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- 229920003002 synthetic resin Polymers 0.000 description 2
- 239000000057 synthetic resin Substances 0.000 description 2
- 229910000906 Bronze Inorganic materials 0.000 description 1
- 239000004677 Nylon Substances 0.000 description 1
- 239000004734 Polyphenylene sulfide Substances 0.000 description 1
- 239000013543 active substance Substances 0.000 description 1
- 125000001931 aliphatic group Chemical group 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 230000004071 biological effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 239000010974 bronze Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 230000008094 contradictory effect Effects 0.000 description 1
- KUNSUQLRTQLHQQ-UHFFFAOYSA-N copper tin Chemical compound [Cu].[Sn] KUNSUQLRTQLHQQ-UHFFFAOYSA-N 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000006837 decompression Effects 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 239000002270 dispersing agent Substances 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 239000003623 enhancer Substances 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000004744 fabric Substances 0.000 description 1
- 238000005187 foaming Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 238000005342 ion exchange Methods 0.000 description 1
- 239000003456 ion exchange resin Substances 0.000 description 1
- 229920003303 ion-exchange polymer Polymers 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 244000005700 microbiome Species 0.000 description 1
- 239000003595 mist Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 239000002105 nanoparticle Substances 0.000 description 1
- 229920001778 nylon Polymers 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 239000012466 permeate Substances 0.000 description 1
- 229920000728 polyester Polymers 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 229920000306 polymethylpentene Polymers 0.000 description 1
- 239000011116 polymethylpentene Substances 0.000 description 1
- 229920000098 polyolefin Polymers 0.000 description 1
- 229920000069 polyphenylene sulfide Polymers 0.000 description 1
- 229920005629 polypropylene homopolymer Polymers 0.000 description 1
- 229920002635 polyurethane Polymers 0.000 description 1
- 239000004814 polyurethane Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- HFQQZARZPUDIFP-UHFFFAOYSA-M sodium;2-dodecylbenzenesulfonate Chemical compound [Na+].CCCCCCCCCCCCC1=CC=CC=C1S([O-])(=O)=O HFQQZARZPUDIFP-UHFFFAOYSA-M 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 229920001059 synthetic polymer Polymers 0.000 description 1
- 239000008399 tap water Substances 0.000 description 1
- 235000020679 tap water Nutrition 0.000 description 1
- 238000005979 thermal decomposition reaction Methods 0.000 description 1
- 229920001187 thermosetting polymer Polymers 0.000 description 1
- 238000001291 vacuum drying Methods 0.000 description 1
- 238000009423 ventilation Methods 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
Abstract
Description
本発明は構成繊維に無機粒子を含有する不織布の製造方法に関する。 The present invention relates to a method for producing a nonwoven fabric containing inorganic particles in constituent fibers.
スパンボンド法やメルトブローン法、エレクトロスピニング法などにより得られる長繊維不織布はバリア性、遮蔽性、軽量性、遮音性などの観点から幅広く用いられている。かかる不織布は素材の熱可塑性もしくは溶媒可溶性を利用して製造される。 Filament nonwoven fabrics obtained by spunbonding, meltblowing, electrospinning, etc. are widely used from the viewpoint of barrier properties, shielding properties, lightness, sound insulation properties, and the like. Such nonwovens are manufactured using the thermoplastic or solvent solubility properties of the material.
上記の加工性を鑑み、従来、合成高分子などに代表される樹脂材料が広く用いられている。光学特性、導電性、誘電性、磁気特性、難燃性、硬度、吸着などの各種機能を向上ならびに変化させたり、微生物の抑制及び活性促進作用、液体やガス状物の吸着分解などのため無機粒子を混和して紡糸することが試みられている。（特許文献１） In view of the above workability, resin materials typified by synthetic polymers have been widely used. Inorganic substances are used to improve and change various functions such as optical properties, conductivity, dielectric properties, magnetic properties, flame retardancy, hardness, and adsorption, to suppress and promote the activity of microorganisms, and to adsorb and decompose liquids and gases. Attempts have been made to blend and spin particles. (Patent document 1)
しかしながら、不織布の製造において、無機粒子の混合により低せん断時の粘度上昇、ノズル付着物の増加、延伸特性の低下、樹脂と無機粒子との混合塊などが生じやすい。また、スパンボンド法やメルトブローン法においては、紡糸時に生じた浮遊粒子を再付着させやすい傾向がある。これらの長繊維不織布は紡糸行程中に、繊維間を接着一体化するため効果的な除去方法が求められている。 However, in the production of nonwoven fabrics, the mixing of inorganic particles tends to cause an increase in viscosity at low shear, an increase in deposits on nozzles, a decrease in stretchability, mixed lumps of resin and inorganic particles, and the like. Further, in the spunbond method and the meltblown method, floating particles generated during spinning tend to reattach. Since these filament nonwoven fabrics adhere and integrate the fibers during the spinning process, an effective removal method is required.
本発明者らが鋭意検討した結果、下記の方法により構成繊維に無機粒子を含有する不織布を効果的に洗浄して製造することを見出し、本発明に到達した。すなわち発明は以下の通りである
１．構成繊維に無機粒子が含有された不織布に対して、界面活性剤及び有機溶媒を含まない水を、吸引及び／又は加圧により厚み方向に通過させる工程を有することを特徴とする不織布の製造方法。
２．前記無機粒子は、平均粒子径０．１μｍ以上１０μｍ以下である上記1に記載の不織布の製造方法。
３．前記構成繊維はポリオレフィン樹脂から成る上記１又は２に記載の不織布の製造方法。
４．前記構成繊維の平均繊維径は０．１μｍ以上３０μｍ以下である上記１から３のいずれか１に記載の不織布の製造方法。
５．スパンボンド法又はメルトブローン法にて前記不織布を作製する工程を有することを特徴とする請求項１から４のいずれ１に記載の不織布の製造方法。
As a result of intensive studies, the present inventors have found that a nonwoven fabric containing inorganic particles in constituent fibers can be effectively washed and produced by the following method, and have arrived at the present invention. That is, the invention is as follows:1. A method for producing a nonwoven fabric, comprising a step of passing water containing no surfactant and organic solvent through a nonwoven fabric containing inorganic particles in constituent fibers in a thickness direction by suction and/or pressure. .
2. 2. The method for producing a nonwoven fabric according to 1 above, wherein the inorganic particles have an average particle size of 0.1 μm or more and 10 μm or less.
3. 3. The method for producing a nonwoven fabric according to 1 or 2 above, wherein the constituent fibers are made of polyolefin resin.
4. 3. The method for producing a nonwoven fabric according to any one of 1 to 3 above, wherein the constituent fibers have an average fiber diameter of 0.1 μm or more and 30 μm or less.
5. 5. The method for producing a nonwoven fabric according to any one of claims 1 to 4, comprising a step of producing the nonwoven fabric by a spunbond method or a meltblown method.
本発明により、構成繊維に無機粒子が含有された不織布において品質を高めることが可能となる。 INDUSTRIAL APPLICABILITY According to the present invention, it is possible to improve the quality of a nonwoven fabric in which inorganic particles are contained in constituent fibers.
以下、本発明に関して具体的に説明するが、本発明は下記に限定される訳ではなく前・後記の趣旨に適合し得る範囲で適当に変更を加えて実施することも可能であり、それらはいずれも本発明の技術的範囲に包含される。 Hereinafter, the present invention will be specifically described, but the present invention is not limited to the following, and can be implemented with appropriate modifications within the scope that can conform to the gist of the preceding and following descriptions. All are included in the technical scope of the present invention.
本発明は不織布の構成繊維に無機粒子が含有された不織布の製造方法に関する。本発明において、不織布は所望の特性を有するものであれば特に制限されないが、スパンボンド法、メルトブローン法、エレクトロスピニング法、フォーススピニング法、レーザー加熱延伸法などにより製造されてなることが好ましい。とりわけ溶媒や紡績油剤等を用いることなく製造が可能な、スパンボンド法、メルトブローン法、レーザー加熱延伸法がより好ましい。これらの製法により得られる繊維（構成繊維）の平均繊維径は０．１μｍ～３０μｍであり、より好ましくは０．５～２０μｍであり、特に好ましくは０．８～１５μｍである。かかる繊維径と無機粒子との組み合わせにより効果的に繊維表面に存在させることが可能となる。 The present invention relates to a method for producing a nonwoven fabric containing inorganic particles in the constituent fibers of the nonwoven fabric. In the present invention, the nonwoven fabric is not particularly limited as long as it has the desired properties, but it is preferably produced by a spunbond method, a meltblown method, an electrospinning method, a force spinning method, a laser heat stretching method, or the like. In particular, the spunbond method, meltblown method, and laser heat drawing method are more preferable because they can be produced without using a solvent, a spinning oil, or the like. The fibers (constituent fibers) obtained by these production methods have an average fiber diameter of 0.1 μm to 30 μm, more preferably 0.5 to 20 μm, and particularly preferably 0.8 to 15 μm. A combination of such a fiber diameter and inorganic particles can be effectively present on the fiber surface.
上記のスパンボンド法、メルトブローン法、レーザー加熱延伸法は繊維表面に粒子を存在させるのに有利な方法であるが、紡糸時に気流を用いた延伸がなされ、捕集ネット上に吸引捕集されるため、浮遊粒子ならびにノズル付着物を持ち込む傾向がある。したがって、本発明における洗浄方法は有利な方法となる。 The above spunbond method, meltblown method, and laser heat drawing method are advantageous methods for allowing particles to exist on the surface of the fiber. Therefore, they tend to introduce airborne particles as well as nozzle deposits. Therefore, the cleaning method of the present invention is an advantageous method.
本発明において、不織布は溶媒可溶性もしくは熱可塑性、熱硬化性を有し繊維化可能な素材であれば特に制限されないが、製造及び取り扱い性の観点から熱可塑性を有する合成樹脂素材であることが好ましい。不織布に可とう性を与え、かつ無機粒子が有する脆性を補うことができるためである。 In the present invention, the nonwoven fabric is not particularly limited as long as it is a material that is solvent-soluble, thermoplastic, or thermosetting and can be made into fibers, but from the viewpoint of manufacturing and handling, it is preferably a thermoplastic synthetic resin material. . This is because it can impart flexibility to the nonwoven fabric and compensate for the brittleness of the inorganic particles.
合成樹脂素材としては所望の特性が得られるものであれば特に制限されないが、無機粒子の機能を勘案して、吸湿や吸水が少なく誘電率の低いポリエステル樹脂もしくは、ポリオレフィン樹脂であることが好ましく、ポリエステル樹脂としては芳香族、脂肪族いずれのものであっても好ましく、ポリオレフィン系としては環状、鎖状いずれでも好ましい。 The synthetic resin material is not particularly limited as long as the desired properties can be obtained, but in consideration of the function of the inorganic particles, it is preferably polyester resin or polyolefin resin with low moisture absorption and water absorption and low dielectric constant. The polyester resin is preferably aromatic or aliphatic, and the polyolefin resin is preferably cyclic or linear.
特に細繊度化された繊維を得るためには、熱分解、ラジカル分解による低分子量化が容易な三級炭素を有する非芳香族樹脂であることが好ましく、具体的にはポリプロピレン樹脂、ポリメチルペンテン樹脂を用いる事が好ましい。低分子量化による細繊度化と無機粒子の繊維内への保持性は相反する事項であるが、本発明においては繊維中に保持されない無機粒子及び、無機粒子と低分子量物からなる飛散物、低延伸塊状物の除去に効果を有する。 In particular, in order to obtain finer fibers, it is preferable to use a non-aromatic resin having a tertiary carbon that is easily reduced in molecular weight by thermal decomposition or radical decomposition. Specifically, polypropylene resin, polymethylpentene It is preferable to use resin. Retention of inorganic particles in fibers is contradictory, but in the present invention, inorganic particles that are not retained in fibers, scattered matter composed of inorganic particles and low-molecular-weight substances, and low-molecular-weight materials It is effective in removing stretch lumps.
本発明において、不織布は、単独の製法、素材からなる均一物であってもよく、製法、素材及び繊維径の異なる２種以上の素材を用いてなる混合物であってもよい。少なくとも一部が本発明により得られればよいものとする。構成繊維が２成分以上から構成されていてもよく、この場合は芯鞘構造の少なくとも外表面側に無機粒子が含まれて成る不織布であればよい。 In the present invention, the nonwoven fabric may be a uniform product made of a single manufacturing method and material, or a mixture of two or more materials having different manufacturing methods, materials and fiber diameters. At least a part should be obtained by the present invention. The constituent fibers may be composed of two or more components, and in this case, a nonwoven fabric containing inorganic particles at least on the outer surface side of the core-sheath structure may be used.
本発明においては、不織布に、光学特性、導電性、誘電性、磁気特性、難燃性、硬度、剛性、生物活性、吸着性、脱臭性等の機能性を付与するために、不織布の構成繊維の表面及び／又は内部に無機粒子を含んでなる。必要特性に応じて無機粒子は１種もしくは２種類以上組み合わせて用いることも可能であり、具体的には炭素、金属、金属酸化物、ガラス等を好ましく用いることができる。 In the present invention, in order to impart functionalities such as optical properties, conductivity, dielectric properties, magnetic properties, flame retardancy, hardness, rigidity, bioactivity, adsorptivity, and deodorizing properties to the nonwoven fabric, constituent fibers of the nonwoven fabric comprising inorganic particles on the surface and/or in the interior of the Inorganic particles can be used singly or in combination of two or more according to the required properties. Specifically, carbon, metal, metal oxide, glass and the like can be preferably used.
無機粒子の添加方法は所望の特性が得られるものであれば特に制限されないが、樹脂重合時に粒子もしく粒子前駆体を添加する方法、マスターバッチ化時に粒子もしくは粒子前駆体を添加する方法、不織布成形時に粒子もしくは粒子前駆体を添加する方法等を例示することができ、単独もしくは組み合わせて用いることができる。 The method of adding the inorganic particles is not particularly limited as long as the desired properties can be obtained, and includes a method of adding particles or particle precursors during resin polymerization, a method of adding particles or particle precursors during masterbatching, and a nonwoven fabric. A method of adding particles or particle precursors at the time of molding can be exemplified, and can be used alone or in combination.
無機粒子の形状としては、板状、針状、球形などいずれの形状であってもよく、安定的に取り扱い可能な一次粒子もしくはアグリゲート二次粒子としての平均粒子径として０．１μｍから１０μｍの大きさが好ましい。より好ましくは０．１μｍ～８μｍであることが好ましく、より好ましくは０．１μｍ～５μｍであり、更に好ましくは０．１μｍ～３μｍであり、特に好ましくは０．１～２μｍである。粒子径が小さい場合にはナノ粒子の懸念があり、大きい場合には分散性が悪くなるとともに繊維形成が困難となる。また、粒子径が０．１μｍよりも小さい場合には水中に洗い出された粒子除去が困難であり、循環水や排水の処理が煩雑となる。 The shape of the inorganic particles may be plate-like, needle-like, spherical, or any other shape, and the average particle size of primary particles or aggregate secondary particles that can be stably handled is from 0.1 μm to 10 μm. size is preferred. It is more preferably 0.1 μm to 8 μm, more preferably 0.1 μm to 5 μm, even more preferably 0.1 μm to 3 μm, and particularly preferably 0.1 to 2 μm. When the particle size is small, there is a concern that the particles may be nanoparticles, and when the particle size is large, the dispersibility deteriorates and fiber formation becomes difficult. If the particle diameter is smaller than 0.1 μm, it is difficult to remove the particles washed out in water, and the treatment of circulating water and waste water becomes complicated.
無機粒子の添加量に関しては、０．０１～１０質量％であることが好ましく、より好ましくは０．０５～７質量％であり、更に好ましくは０．１～５質量％であり、特に好ましくは０．２～３質量％である。 The amount of inorganic particles added is preferably 0.01 to 10% by mass, more preferably 0.05 to 7% by mass, still more preferably 0.1 to 5% by mass, and particularly preferably It is 0.2 to 3% by mass.
無機粒子に関しては流動性、分散性などを考慮し、各種分散剤や粘着防止剤をコーティングして用いることも知られているが、本発明においては低分子のブリード物を洗浄除去する効果も得られる。 Inorganic particles are known to be coated with various dispersants or anti-tacking agents in consideration of fluidity and dispersibility. be done.
上記樹脂からなる不織布は、洗浄のための液体を浸透させることが困難であり、有機溶媒もしくは、界面活性剤又は有機溶媒を含有する水を用い洗浄する必要があったが、多孔質と界面活性剤の併用では泡立ちの問題があり、有機溶媒の使用では環境面に悪影響がある。したがって、本発明においては洗浄に界面活性剤及び有機溶媒を含有しない水を用いることを特徴とする。 It is difficult to permeate the nonwoven fabric made of the above resin with a liquid for washing, and it has been necessary to wash it with an organic solvent, a surfactant, or water containing an organic solvent. Concomitant use of agents presents foaming problems, and the use of organic solvents has a negative environmental impact. Therefore, the present invention is characterized by using water containing neither a surfactant nor an organic solvent for washing.
本発明に用いられる水としては、洗浄効果が得られるものであれば特に制限されないが、乾燥残留物の観点から無機塩及び高沸点有機物が少ないことが好ましく、イオン交換樹脂、逆浸透膜などを使用し、高度に浄化されたものを用いることが特に好ましい。イオン性の不揮発分を低減することで更なる清浄化が期待されるためである。 The water used in the present invention is not particularly limited as long as the cleaning effect can be obtained, but from the viewpoint of dry residue, it is preferable that the amount of inorganic salts and high boiling point organic substances is small, and ion exchange resins, reverse osmosis membranes, etc. are preferably used. It is particularly preferred to use one that has been used and highly purified. This is because further cleaning is expected by reducing the ionic non-volatile matter.
本発明においては洗浄に界面活性剤及び有機溶媒を含有しない水を用いることで、樹脂よりも相対的に極性の高い粒子状物を効果的に洗い落とし、かつ無機粒子を分散させるために用いられる界面活性剤等を洗浄除去し粒子表面を清浄化する有利な効果が得られる。また、繊維充填層に電荷を与えることも可能であり、乾燥後の使用時における粒子状物の飛散や脱落を更に低減させる効果が得られる。特に一次粒子径０．１μｍ以下からなる二次粒子を用いる場合には、使用時の破砕による再飛散を抑制する必要があり、本発明による洗浄は特に有利である。 In the present invention, by using water that does not contain a surfactant and an organic solvent for washing, particulate matter that is relatively more polar than the resin is effectively washed off, and the interface used to disperse the inorganic particles Advantageously, the surface of the particles is cleaned by washing away active agents and the like. It is also possible to give an electric charge to the fiber-filled layer, which has the effect of further reducing scattering and falling off of particulate matter during use after drying. In particular, when using secondary particles having a primary particle size of 0.1 μm or less, it is necessary to suppress re-entrainment due to crushing during use, and the cleaning according to the present invention is particularly advantageous.
本発明においては、不織布を洗浄するために、吸引及び／又は加圧により水を保持させ、厚み方向に通過させたのち、除去、乾燥させる。水を保持ならびに通過させる方法としては、所望の効果が得られるものであれば特に制限されないが、噴射、圧入、凝縮、吸引などの方法を用いることが可能であり、除去及び乾燥方法としては、吸引もしくは雰囲気の減圧、熱及び電磁波などを利用した加熱などを用いることができる。噴射と減圧の組合せが通液、洗浄、乾燥の工程として好ましい。 In the present invention, in order to wash the nonwoven fabric, water is retained by suction and/or pressure, passed through the nonwoven fabric in the thickness direction, then removed and dried. The method for retaining and passing water is not particularly limited as long as the desired effect can be obtained, but methods such as injection, injection, condensation, and suction can be used. Methods for removing and drying include: Heating using suction, atmospheric pressure reduction, heat, electromagnetic waves, or the like can be used. A combination of jetting and depressurization is preferable as the steps of liquid passing, washing, and drying.
噴射及び減圧の圧力としては、処理される不織布の強度ならびに通液性ならびに支持体の特性に応じて好ましく調整することができる。疎水性材料に対しては、ミスト状の水を吸引させることで気液混合体を通過させ、浸透性を高めることが好ましい方法である。また噴流による凝集塊の破砕効果も考慮される。 The injection and decompression pressures can be preferably adjusted according to the strength and liquid permeability of the nonwoven fabric to be treated and the properties of the support. For hydrophobic materials, a preferred method is to suck water mist to allow the gas-liquid mixture to pass through, thereby increasing permeability. Also, the effect of crushing agglomerates by the jet is taken into consideration.
具体的な方法例として、処理される不織布を通気度５０～４００ｃｍ３／ｃｍ２／秒の網状支持体に載せ、この上方より水を噴射するとともに、該網状支持体の下方を減圧状態とすることが好ましい。通気度はＪＩＳ Ｌ１０９６に記載のフランジール形試験機を用いて測定できる。 As a specific example of the method, the nonwoven fabric to be treated is placed on a mesh support having an air permeability of 50 to 400 cm 3 /cm 2 /sec, water is jetted from above, and the bottom of the mesh support is reduced in pressure. is preferred. The air permeability can be measured using a frandil type tester described in JIS L1096.
具体的な方法例として、網状支持体とは具体的には金属ヤーンやプラスチックヤーンの織物からなる多孔構造物であり、平織り、綾織り、朱子織りなどの織り形状が挙げられる。金属素材としてはステンレス、ブロンズ等、またプラスチック素材としてはポリプロピレン、ポリエステル、ポリウレタン、ナイロン、ポリフェニレンサルファイドなどがある。 As a specific method example, the net-like support is specifically a porous structure made of a fabric of metal yarn or plastic yarn, and includes plain weave, twill weave, satin weave, and the like. Examples of metal materials include stainless steel and bronze, and examples of plastic materials include polypropylene, polyester, polyurethane, nylon, and polyphenylene sulfide.
具体的な方法例として、水噴射は長繊維不織布の数ｃｍ上方に設置されたノズルより、洗浄及び厚さ方向に通水するのに十分な圧力で噴射する。十分な圧力は、特に定めないが、ノズルの孔形状及び長繊維不織布の目付によって異なる。例えば、目付が５～５０ｇ／ｍ２の場合には、０．３～３ＭＰａ、５０～２００ｇ／ｍ２のシートに対しては、１～４ＭＰａであることが好ましい。噴射の圧力が高すぎると、ピンホールや破断が生じる。また圧力が低すぎると十分に水が通過することができず洗浄が不十分となる。 As a specific example of the method, the water is jetted from a nozzle placed several cm above the long-fiber nonwoven fabric at a pressure sufficient to wash and pass the water in the thickness direction. Sufficient pressure is not specified, but varies depending on the shape of the nozzle holes and the basis weight of the long-fiber nonwoven fabric. For example, when the basis weight is 5 to 50 g/m 2 , it is preferably 0.3 to 3 MPa, and for a sheet of 50 to 200 g/m 2 , it is preferably 1 to 4 MPa. If the injection pressure is too high, pinholes and breaks will occur. On the other hand, if the pressure is too low, sufficient water cannot pass through, resulting in insufficient cleaning.
具体的な方法例として、ノズルは直径０．０５～０．２ｍｍの孔を、０．５～３ｍｍピッチで１列あるいは複数列配置したものが例示される。また、例えば網状支持体を可動とし、長繊維不織布を長手方向に搬送させることにより噴射処理を連続的に行うことができるものが好ましい。搬送速度は特に限定されないが、好ましい範囲を挙げると、１～１００ｍ／分である。また最適な噴射回数や処理面（片面か両面か）は長繊維不織布の目付や平均繊維径に依存するため、特に限定されない。 As a specific example of the method, the nozzle has holes with a diameter of 0.05 to 0.2 mm arranged in one or more rows at a pitch of 0.5 to 3 mm. In addition, it is preferable that the net-like support is made movable and the long-fiber nonwoven fabric is conveyed in the longitudinal direction so that the jetting treatment can be continuously performed. The conveying speed is not particularly limited, but a preferable range is 1 to 100 m/min. Also, the optimum number of injections and the treatment surface (one side or both sides) are not particularly limited because they depend on the basis weight and average fiber diameter of the long-fiber nonwoven fabric.
具体的な方法例として、水噴射と同時に、網状支持体の下方を、排気ブロアー等を用いて減圧状態とすることが好ましい。吸引時の負圧は特に限定されないが、－０．０１～－０．５ｋＰａが好適である。減圧状態にすると、長繊維不織布内を効果的に水が通過し、かつ保水量を減らすことができる。 As a specific example of the method, it is preferable to reduce the pressure under the net-like support by using an exhaust blower or the like at the same time as the water injection. The negative pressure during suction is not particularly limited, but -0.01 to -0.5 kPa is preferable. When the pressure is reduced, water can effectively pass through the long-fiber nonwoven fabric and the amount of retained water can be reduced.
具体的な方法例として、水噴射処理後の乾燥方法については、熱風乾燥法、真空乾燥法、自然乾燥法等の方法が適用可能である。これらのうちでも熱風乾燥法は、連続処理が可能であるため好ましい。熱風乾燥法の場合、繊維の溶融及びフィルム化を生じない程度の温度にする必要がある。好ましくは１２０℃以下、より好ましくは１００℃以下、さらに好ましくは８０℃以下にするのがよい。また、熱風乾燥前に、予備乾燥として、吸水ロール、サクション吸引等によって過剰な水分を取り除いておくことがより好ましい。 As a specific method example, a method such as a hot air drying method, a vacuum drying method, or a natural drying method can be applied as a drying method after the water injection treatment. Among these, the hot air drying method is preferable because continuous treatment is possible. In the case of the hot air drying method, the temperature must be such that the fibers do not melt or form a film. The temperature is preferably 120° C. or lower, more preferably 100° C. or lower, and even more preferably 80° C. or lower. In addition, it is more preferable to remove excess water by using a water absorbing roll, suction suction, or the like as preliminary drying before hot-air drying.
本発明においては不織布に帯電増強剤などが含まれていてもよい。洗浄時に繊維が電荷を帯びることで不織布内部に含まれる無機粒子が繊維層に捕捉されるため、発じんの抑制に更なる効果を有する。 In the present invention, the nonwoven fabric may contain an electrification enhancer or the like. Since the fibers are charged during washing, the inorganic particles contained in the nonwoven fabric are trapped in the fiber layer, which is further effective in suppressing dust generation.
本発明の不織布の製造方法により得られる不織布も本発明の範疇に含まれる。本発明によって得られる不織布は、添加させる無機粒子により増強される、光学特性、導電性、誘電性、磁気特性、難燃性、硬度、剛性、生物活性、吸着性、脱臭性等の機能性を有した各種用途に用いることができる。一般生活環境ならびに各種産業用、機器組み込みなどに好適である。 The nonwoven fabric obtained by the method for producing a nonwoven fabric of the present invention is also included in the scope of the present invention. The nonwoven fabric obtained by the present invention has functionalities such as optical properties, conductivity, dielectric properties, magnetic properties, flame retardancy, hardness, rigidity, biological activity, adsorptivity, and deodorizing properties, which are enhanced by the inorganic particles added. It can be used for various uses. It is suitable for general living environment, various industrial uses, and built-in equipment.
以下に本発明を例示する。
＜走査型電子顕微鏡による付着粒子の計測＞
不織布から採取した試料表裏をフィルダーにセットし、走査型電子顕微鏡の反射電子検出器を用いて、低真空もしくはカーボン蒸着された試料にて視野範囲０．５ｍｍ×０．５ｍｍでの画像取得を行う。無機粒子は反射電子強度が高いため、ポリオレフィン樹脂とは明るさの異なる粒状物もしくは塊状物として識別できる。識別困難な場合には必要に応じてＥＤＳによる元素特定を行う。
The present invention is exemplified below.
<Measurement of Adhering Particles Using a Scanning Electron Microscope>
Set the front and back of the sample collected from the nonwoven fabric on the filter, and use the backscattered electron detector of the scanning electron microscope to acquire an image in a low vacuum or carbon-deposited sample with a field of view of 0.5 mm × 0.5 mm. . Since the inorganic particles have a high intensity of backscattered electrons, they can be distinguished from the polyolefin resin as granular substances or lumps with different brightness. If identification is difficult, the element is specified by EDS as necessary.
＜不織布の作製＞
ＭＦＲ１３００のポリプロピレンホモポリマー１００質量部に対し、平均粒子径０．７μｍの酸化亜鉛粒子を０．３質量部混合し、メルトブローン法にて目付３０g/ｍ２、幾何平均による繊維径２．８μｍの長繊維不織布を得た。走査型電子顕微鏡を用いた観察により、繊維に表出する樹脂と一体化した酸化亜鉛粒子ならびに不織布表層及び繊維層内部に繊維と一体化していない酸化亜鉛粒子を確認した。表裏各々３視野、合計６視野の画像を取得した結果、短径１０μｍ以上の付着凝集物を合計１７個確認した。
<Preparation of nonwoven fabric>
0.3 parts by mass of zinc oxide particles with an average particle size of 0.7 μm are mixed with 100 parts by mass of a polypropylene homopolymer having an MFR of 1300, and a basis weight of 30 g/m 2 is obtained by a meltblown method, and a length of fiber diameter of 2.8 μm by geometric mean is obtained. A fibrous nonwoven fabric was obtained. By observation using a scanning electron microscope, zinc oxide particles that were integrated with the resin exposed on the fibers and zinc oxide particles that were not integrated with the fibers were confirmed on the surface layer of the nonwoven fabric and inside the fiber layer. As a result of acquiring images of 6 fields of view in total, 3 fields of view on each of the front and back surfaces, a total of 17 adhering aggregates with a minor axis of 10 μm or more were confirmed.
＜実施例１＞
上記不織布の作製にて得られた不織布を通気度１２０ｃｍ３／ｃｍ２／秒の網状支持体（９６メッシュ）に載せ、支持体の上方２ｃｍに位置する直径０．１ｍｍφ、ピッチ０．６ｍｍのノズルから、１ＭＰａの圧力で水の噴射処理を行った。使用した水は、一般的な水道水を逆浸透膜処理した後にイオン交換法にて精製を行ったものである。この水は、１μＳ／ｃｍ２以下の導電率であった。この水は、界面活性剤及び有機溶媒を含有しない水である。
網状支持体の搬送速度を４ｍ／分とし、ノズル直下の網状支持体の下方を－０．２０ｋＰａの減圧状態とした。この処理をシートの表裏について各１回ずつ行った後、更に水を噴射せず減圧のみ実施した状態で速度４ｍ／分で通過させることで脱水し２５℃にて風乾を行った。走査型電子顕微鏡による付着粒子の計測を行ったところ、合計６視野において短径１０μｍ以上の付着凝集物は確認されなかった。
<Example 1>
The nonwoven fabric obtained in the production of the above nonwoven fabric was placed on a mesh support (96 mesh) with an air permeability of 120 cm 3 /cm 2 /sec, and nozzles with a diameter of 0.1 mmφ and a pitch of 0.6 mm were positioned 2 cm above the support. Then, water injection treatment was performed at a pressure of 1 MPa. The water used was ordinary tap water treated with a reverse osmosis membrane and then purified by an ion exchange method. This water had a conductivity of 1 μS/cm 2 or less. This water is water free of surfactants and organic solvents.
The conveying speed of the net-like support was 4 m/min, and the pressure under the net-like support immediately below the nozzle was reduced to -0.20 kPa. After this treatment was performed once for each of the front and back sides of the sheet, the sheet was dehydrated by passing at a speed of 4 m/min while only reducing pressure without jetting water, and air-dried at 25°C. Adhered particles were measured with a scanning electron microscope, and no adhered aggregates with a minor axis of 10 μm or more were observed in a total of six fields of view.
＜比較例１＞
上記不織布の作製にて得られた不織布を、実施例１と同様の水の中にくぐらせた後に２５℃にて風乾を行った。疎水性であるため水は不浸透であり、走査型電子顕微鏡を用いた観察により、合計６視野において、走査型電子顕微鏡による付着粒子の計測を行ったところ、短径１０μｍ以上の付着凝集物は１３個確認された。
<Comparative Example 1>
The nonwoven fabric obtained in the production of the above nonwoven fabric was passed through the same water as in Example 1, and then air-dried at 25°C. Since it is hydrophobic, it is impermeable to water, and by observation using a scanning electron microscope, the adhered particles were measured by a scanning electron microscope in a total of 6 fields of view. 13 confirmed.
＜比較例２＞
上記不織布の作製にて得られた不織布を、浸透剤としてラウリルベンゼンスルホン酸ナトリウム０．１質量％を含む水に浸漬させることで、不織布内部まで保水させた。実施例１と同様の条件にて減圧脱水のみ行った結果、減圧側に多量の気泡が発生し不織布表面からの除去及び気液分離が困難であった。走査型電子顕微鏡を用いた観察により、合計６視野において短径１０μｍ以上の付着凝集物は４個確認された。
<Comparative Example 2>
The nonwoven fabric obtained in the production of the nonwoven fabric was immersed in water containing 0.1% by mass of sodium laurylbenzenesulfonate as a penetrating agent to retain water inside the nonwoven fabric. As a result of carrying out only dehydration under reduced pressure under the same conditions as in Example 1, a large amount of air bubbles were generated on the reduced pressure side, making it difficult to remove them from the surface of the nonwoven fabric and to separate gas and liquid. Observation using a scanning electron microscope confirmed 4 adhering aggregates with a minor axis of 10 μm or more in a total of 6 fields of view.
＜比較例３＞
上記不織布の作製にて得られた不織布に対して、実施例１において水の噴射処理を行わず、減圧のみを実施することで表裏面の通気を行った。走査型電子顕微鏡を用いた観察により、合計６視野において、短径１０μｍ以上の付着凝集物は１０個確認された。
<Comparative Example 3>
The nonwoven fabric obtained in the production of the above nonwoven fabric was not subjected to the water jetting treatment in Example 1, but was subjected to pressure reduction only to perform ventilation on the front and back surfaces. Observation using a scanning electron microscope confirmed 10 adhering aggregates with a minor axis of 10 μm or more in a total of 6 fields of view.
実施例１及び比較例１～３より分かるように、気流もしくは流水のみを用いた場合には繊維径が小さく疎水性素材であるポリオレフィン不織布の洗浄は困難であることがわかる。界面活性剤を含む場合には浸透は可能であるが凝集物の除去効果が不十分かつ実用性に劣る。液体として界面活性剤及び有機溶媒を含まない水を用いて洗浄することで、紡糸により生成した無機粒子を含む付着物を効果的に除去し、かつ作業性に優れることがわかる。 As can be seen from Example 1 and Comparative Examples 1 to 3, it is difficult to wash the polyolefin nonwoven fabric, which is a hydrophobic material with a small fiber diameter, when only air flow or running water is used. When a surfactant is included, penetration is possible, but the effect of removing aggregates is insufficient and the practicality is poor. It can be seen that by washing with water that does not contain a surfactant and an organic solvent as a liquid, deposits containing inorganic particles generated by spinning can be effectively removed, and workability is excellent.
本発明により、構成繊維に無機粒子を含有する不織布を品質を高めて製造することが可能となり、産業上有用である。
INDUSTRIAL APPLICABILITY According to the present invention, it is possible to produce a nonwoven fabric containing inorganic particles in constituent fibers with improved quality, which is industrially useful.
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