JP3169133B2 - Modified water absorbent resin particles for sanitary goods - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to water-absorbent resin particles treated with an organopolysiloxane. More specifically, the present invention relates to a water-absorbent resin particle for sanitary goods treated and modified with a liquid organic polysiloxane, which has an improved absorption rate and has little problem of blocking due to moisture absorption.

BACKGROUND ART Conventionally, water-absorbent resins have been widely used for sanitary products, sanitary materials such as disposable diapers, and the like. Examples of such water-absorbent resins include crosslinked polyacrylates, self-crosslinked polyacrylates, crosslinked starch-acrylate graft copolymers, crosslinked vinyl alcohol-acrylate copolymers, A substantially water-insoluble crosslinked polymer such as a hydrolyzate of a crosslinked acrylamide copolymer, a neutralized product of a crosslinked isobutylene-maleic anhydride copolymer, and a crosslinked product of a carboxymethyl cellulose salt is known.

However, although conventional water-absorbent resins have a high absorption capacity, they are not sufficiently satisfactory for use in sanitary products such as disposable diapers and sanitary products that require a high absorption rate. Is generally used in combination with a fibrous material such as pulp having a high absorption rate.

In other words, the higher the absorption capacity of the water-absorbing resin is, the higher the affinity with water becomes, so that when the resin particles come into contact with water, gelation occurs at the contact portion and uniform penetration of water into the inside of the particles is achieved. There was a problem that the absorption speed was reduced as a result.

In order to improve this drawback, attempts have been made to increase the absorption rate by increasing the surface area by making the water-absorbent resin particles finer and increasing the contact area with water. The absorption rate is somewhat faster due to the increased surface area. However, since a film is formed on the surface of the resin particles by contact with water at the point of contact with water, and the particles adhere to each other and uniform water penetration is impaired. It did not lead to improvement.

In addition to the above problems, the conventional water-absorbent resin particles absorb the moisture and block the resin particles in the process of storing the resin under high humidity or supplying the resin to a manufacturing machine such as a disposable diaper because of its high absorbency. Therefore, there is a problem that the water-absorbent resin is discharged from the hopper and continuous quantitative supply to the machine is impossible due to the moisture absorption blocking.

As a method of improving the moisture absorption blocking property, the following methods have been proposed.

A method in which finely divided hydrophobic silica having an average particle diameter of 0.05 μm or less and a specific surface area of 50 m ² / g or more is mixed with the water-absorbent resin particles (JP-A-56-133028).

A method in which inorganic powders such as hydrous silicon dioxide, hydrous aluminum hydroxide, and hydrous titanium oxide are added to the water-absorbent resin particles (Japanese Patent Laid-Open No. 59-80459).

After treating the water-absorbent resin particles with a cationic surfactant, a powder of a high melting point organic compound is further added (JP-A-61-69854).

Mix stearic acid and inorganic powder with water-absorbent resin particles,
Method of coating resin surface with stearic acid
No. 105064).

However, in the above method, although the moisture absorption blocking property can be improved by the addition of the hydrophobic silica, the surface of the resin particles is covered with the hydrophobic silica, so that the absorption rate, the initial absorption amount under pressure and the absorption capacity are reduced, There is a problem that a large amount of dust is generated because fine powdered silica is mixed.

In the above method, if the inorganic powder is not hydrophobic,
Although the initial absorption amount under pressure and the absorption capacity do not decrease much, the improvement of the moisture absorption blocking property is insufficient, and there is a problem that a large amount of dust is generated as described above because the inorganic powder is in the form of fine powder. Was. In addition, when the inorganic powder is hydrophobic, there is the same problem as described above.

In the above method, since the surface of the hydrophobic high melting point organic compound or the stearic acid resin particles is covered, improvement of the moisture absorption blocking property is possible to some extent, but it is not sufficient, and the high melting point organic compound or the stearic acid absorbs water. There is a problem that the initial absorption amount under pressure and the absorption capacity are reduced because the absorption of the hydrophilic resin is inhibited.

Therefore, the present invention is to modify the water absorbent resin particles, water,
It is a first object of the present invention to provide water-absorbent resin particles for sanitary goods having a high absorption rate by promoting uniform penetration of urine, menstrual blood and the like into water-absorbent resin particles.

Further, the present invention is to modify the water-absorbent resin particles, the above-mentioned ~
A second object of the present invention is to provide a water-absorbent resin particle for hygiene articles which solves the problems in the method of improving the moisture-absorbing blocking property such as the moisture-absorbing blocking rate and the dustiness, and has an excellent initial absorption amount under pressure and an excellent absorption capacity. The purpose is.

DISCLOSURE OF THE INVENTION The present invention is a crosslinked polymer of an ethylenically unsaturated monomer having acrylic acid and / or an acrylate as a main structural unit, and particles of a water-insoluble resin (A) which is substantially water-insoluble. Is a modified water-absorbent resin particle for sanitary goods treated with an organic polysiloxane (B) which is liquid at normal temperature, wherein (A) and (B) are mixed and / or reacted; ) Wherein the content of particles of 10 to 1,000 μm is 95% by weight or more and the weight ratio (A) / (B) is 100 / (0.001 to 3). It is intended to provide conductive resin particles.

That is, the modified water-absorbent resin particles for sanitary goods of the present inventor is obtained by modifying the water-absorbent resin (A) with the organic polysiloxane (B). The surface of the particles of (A) is in a state where (B) is adhered, or (A) and (B) react and (B) is fixed to the surface of the particles of (A). Depending on the presence or absence of the reactivity between (A) and (B), either a mixed state or a reactive state is achieved.

In any state, since the surface of the particles (A) is modified with the liquid organic polysiloxane (B), the modified water-absorbent resin particles of the present invention can be used under high humidity. At the same time as improving the moisture absorption blocking property, imparting wettability and preventing generation of dust.

In addition, in the present invention, the disadvantage that the particles of the water-absorbent resin adhere to each other to impair uniform water penetration is improved by the modification effect of (B) in the present invention, so that the absorption rate is improved. It was done.

Furthermore, the modified water-absorbent resin particles for hygiene articles of the present inventor are also excellent in the initial absorption amount under pressure and the absorption capacity.

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the water-absorbent resin (A) absorbs a large amount of water when contacted with water and swells to form a hydrogel (hydrogel). Is a water-insoluble resin.
The water absorbent resin (A) is a crosslinked polymer of an ethylenically unsaturated monomer having acrylic acid and / or acrylate as a main constituent unit.

Examples of such water-absorbent resin (A) include a crosslinked product of a partially neutralized polyacrylic acid, a partially neutralized self-crosslinked polyacrylic acid, a crosslinked product of a starch-acrylate graft copolymer, and a starch-neutralized product. Hydrolyzate of crosslinked acrylonitrile graft polymer, crosslinked product of vinyl alcohol-acrylate copolymer, hydrolyzate of crosslinked acrylate-acrylamide copolymer, hydrolysis of crosslinked acrylate-acrylonitrile copolymer Degradation products, acrylates and 2-
A crosslinked product of an acrylamide-2-methylpropanesulfonic acid salt, a neutralized product of a crosslinked isobutylene-maleic anhydride copolymer, and a combination of two or more thereof are exemplified.

Each of the crosslinked polymers exemplified above as the water-absorbent resin (A) is obtained by using a carboxylate such as an acrylate as a raw material, or forming a salt by being a neutralized product or a partially neutralized product. As the salt in this case, a sodium salt, a potassium salt, an ammonium salt, an amine salt and the like are used. Preferred are sodium and potassium salts.

Preferred among those exemplified as the water-absorbing resin (A) are the cross-linked polyacrylic acid partially neutralized products and the self-cross-linked polyacryl, considering the absorption characteristics when finally used as a water-absorbing resin. An acid partially neutralized product, a crosslinked product of a starch-acrylate graft copolymer and a crosslinked product of a vinyl alcohol-acrylate copolymer.

The water-absorbent resin (A) has an absorption performance at normal pressure of physiological saline (0.9% aqueous sodium chloride solution) at normal pressure of 30 times or more, preferably 35 to 80 times, and more preferably 40 times or more of its own weight.
It is preferable to use the one of up to 70 times.

Regarding the particle size distribution of the particles of the water absorbent resin (A),
Among the particles of (A), it is necessary to use water-absorbent resin particles having a particle size distribution in which the content of particles having a particle size of 10 to 1,000 μm is 95% by weight or more. 85
It is desirable to use water-absorbing resin particles having a particle size distribution in which the content of 0 μm particles is 95% by weight or more. Particle size
In the case of using water-absorbing resin particles having a particle size distribution in which the content of particles of 10 to 1,000 μm has a particle size distribution of less than 95 wt%,
It is not preferable because it easily becomes a cage when absorbing water, and the absorption speed is reduced. On the other hand, when the water-absorbent resin particles having a particle size distribution containing a large number of particles having a large particle size are used, it takes a long time to absorb water to the inside of the particles when absorbing water. . The average particle size is not particularly limited, but is preferably from 200 to 600 μm.

The shape of the particles of the water absorbent resin (A) is not particularly limited,
Depending on the manufacturing method, pearl-like obtained by reversed-phase suspension polymerization,
Examples include flakes obtained by drum drying, rocky or amorphous shapes obtained by pulverizing a resin mass, and granules of these particles.

In the present invention, the organic polysiloxane (B) only needs to be liquid at normal temperature, and may or may not have reactivity with the water absorbent resin (A). That is, (B) includes those having no reactivity with the carboxylic acid (salt) group in the water absorbent resin (A) and those having reactivity with the carboxylic acid (salt) group.
(Here, “carboxylic acid (salt) group” means a carboxylic acid group and / or a carboxylate group, and the same applies to the following). By the way, an organic silicon monomer, which is generally called a silane coupling agent, is a monomer having a relatively low molecular weight, and a desired effect cannot be obtained only by mixing the same. Therefore, as the organic polysiloxane (B), Is not suitable.

Among (B), those having no reactivity with (A) include, for example, dimethyl silicone oil, methyl hydrogen silicone oil, methyl phenyl silicone oil, cyclic dimethyl silicone oil, polyether-modified silicone oil, carboxyl-modified silicone Oil, alkyl-modified silicone oil, alkoxy-modified silicone oil, and the like. These can be used in combination of two or more. Emulsions in which these are emulsified in water can also be suitably used in the present invention.

Among (B), those having reactivity with (A) include silicone oils having at least one functional group that reacts with a carboxylic acid (salt) group contained in (A). Examples include amino-modified silicone oil, epoxy-modified silicone oil, carbinol-modified silicone oil, phenol-modified silicone oil, and mercapto-modified silicone oil.

Among those having no reactivity with (A), preferred are dimethyl silicone oil and polyether-modified silicone oil in that they are relatively inexpensive.

Among those having reactivity with (A), preferred are amino-modified silicone oils and epoxy-modified silicone oils capable of reacting with carboxylic acid (salt) groups at relatively low temperatures. Particularly preferred is an amino-modified silicone oil in that it can react with a carboxylic acid (salt) group at room temperature.

The amino-modified silicone oil includes -R ¹ NR ² R at the terminal and / or in the molecule of the silicone polymer molecule.
³ (where R ¹ is an alkylene group having 1 to 12 carbon atoms; R ² and R ³ are H or an alkyl group having 1 to 12 carbon atoms. One or more hydrogen atoms of the alkylene group and / or the alkyl group are OH Group,
May be substituted by a COOH group, an NH ₂ group, or the like, and when the number of carbon atoms is 2 or more, an ether bond containing an oxygen atom may be contained between carbon-carbon bonds.) And the like. Amino-modified silicone oil having

As the epoxy-modified silicone oil, -RX (where R is an alkylene group having 1 to 12 carbon atoms; X is an epoxy group. One or more hydrogen atoms of the alkylene group is May be substituted with an OH group, a COOH group, or the like, and when the alkylene group has 2 or more carbon atoms, an ether bond containing an oxygen atom may be included between carbon-carbon bonds.) And the like. Epoxy-modified silicone oil having a group represented by

Among the above (B), among those having no reactivity with (A) and those having reactivity, there is no fear of separation from the resin particle surface at the time of moisture absorption, and it has adhesion to (A). Considering that it is expected that the product has a large reforming effect and requires a small amount of use, a product having reactivity is preferable.

In the above (B), the number of the reactive functional groups of the organopolysiloxane having the reactivity with the (A) may usually be one or more in one molecule of the silicone oil. However, it is preferable that two or more functional groups are provided for the purpose of crosslinking the vicinity of the surface of the resin particles. A more preferred number of reactive functional groups is 2 from the viewpoint of efficient crosslinking.
~ 20. Further, the position of the functional group may be any of terminal, side chain or both terminal and side chain of the silicone polymer molecule.

The organic polysiloxane (B) may be liquid at ordinary temperature, and its molecular weight is not particularly limited, but is preferably 1,000 or more, more preferably 3,000 or more. The upper limit of the molecular weight of the organopolysiloxane (B) is not particularly limited, but is usually about 1,000,000. Molecular weight 1,0
The use of an organic polysiloxane of 00 or more is preferable because the moisture absorption blocking rate and the degree of dust do not deteriorate over time.

The surface tension of the organopolysiloxane (B) is not particularly limited, but is preferably 18 to 30 dynes / cm, more preferably 2 to 30 dynes / cm.
0-26 dynes / cm. When an organic polysiloxane having a surface tension in the above range is used, it is possible to prevent (B) from easily penetrating into the water-absorbent resin particles. Therefore, in order to achieve the desired effect, (B) must be added in a large amount. It is economical because it does not need to be used, and the water repellency is not so strong that there is no possibility that the absorption performance is reduced. In addition, there is no possibility that problems such as poor powder fluidity and occurrence of blocking may occur, which is preferable. The surface tension is a value measured at 25 ° C.

The viscosity of (B) is not particularly limited as long as it is liquid at normal temperature, but is preferably 10 to 20,000 centistokes (cst) at normal temperature (25 ° C.), and particularly preferably needs to be diluted with a solvent. And easy to mix with (A)
~ 1,000cst.

By using an organic polysiloxane having the above viscosity, it can be used after being diluted with a low-viscosity organic polysiloxane or another solvent (eg, methyl ethyl ketone, cellosolves, lauryl alcohol, etc.), or after being mixed with (A), It is economical because there is no need to add a step for removing the solvent used for dilution, the powder fluidity is kept good, and (B) hardly penetrates into the water-absorbent resin particles. It is not necessary to use a large amount of (B) in order to obtain the desired effect. Therefore, (B) acts as a binder between the particles of (A) to slow down the absorption rate or cause blocking. Preferred for reasons such as not. In addition,
The viscosity is a value measured at 25 ° C.

The amount of the organic polysiloxane (B) to be used with respect to the particles of the water-absorbent resin (A) can be varied in various ways, but is usually 100: (0.00) by weight ratio of the particles of (A) :( B).
1-5), preferably 100: (0.01-3), especially 100: (0.0
1-1).

When the proportion of (B) is less than 0.001, the effect on the moisture absorption blocking ratio is not sufficient, and it is difficult to say that the water-absorbent resin composition has an improved absorption rate.

On the other hand, when it exceeds 5, it is effective for improving the absorption rate, but it causes another problem such as a decrease in absorption performance, poor powder flowability, and occurrence of blocking.

Further, not only the particles of the water-absorbent resin (A) used in the present invention are treated and modified with (B), but also the surface vicinity of the particles (A) can react with a carboxylic acid (salt) group. Water-absorbent resin particles having a modified structure further cross-linked with a cross-linking agent (C) having at least two groups have a further improved absorption rate and a higher gel strength, and are therefore preferably used in the present invention. be able to.

There is no particular limitation on the timing of the surface cross-linking of the particles of (A) with the cross-linking agent (C), before the treatment of the particles of (A) with (B), simultaneously with the treatment with (B), or with (B). Any of after the processing may be used.

The type of the cross-linking agent (C) depends on the water-absorbing resin (A) used.
And the type of the organic polysiloxane (B), for example, polyglycidyl ether compounds, polyol compounds, polyamine compounds, polyamine resins, carbonate compounds, haloepoxy compounds, polyaldehyde compounds, etc. No.

Specific examples of the polyglycidyl ether compound include, for example, ethylene glycol diglycidyl ether, glycerin-1,3-diglycidyl ether, glycerin triglycidyl ether, polyethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, Glycerin polyglycidyl ether and the like can be mentioned.

Specific examples of the polyol compound include, for example, glycerin, ethylene glycol, polyethylene glycol,
Examples include polypropylene glycol and diethanolamine.

Specific examples of the polyamine compound include, for example, ethylenediamine, diethylenetriamine, triethylenetetramine, and the like.

Specific examples of the polyamine-based resin include, for example, polyamide polyamine epichlorohydrin resin, polyamine epichlorohydrin resin, and the like.

Specific examples of the carbonate-based compound include, for example, ethylene carbonate.

Specific examples of the haloepoxy compound include, for example, epichlorohydrin, α-methylepichlorohydrin, and the like.

Specific examples of the polyaldehyde compound include, for example,
Glutaraldehyde, glyoxal and the like can be mentioned.

As described above, preferred examples of the cross-linking agent (C) are preferable in that a water-absorbent resin particle having excellent absorption rate and gel strength can be obtained by forming a strong covalent bond with a carboxylic acid (salt) group. And a polyglycidyl ether compound, a polyol compound and a polyamine resin.
Even more preferred are ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, glycerin-1,3-diglycidyl ether, glycerin triglycidyl ether, and polyamine, which are economical in terms of reaction temperature and energy cost. Epichlorohydrin resin and polyamide polyamine epichlorohydrin resin.

The amount of the crosslinking agent (C) used depends on the type of the crosslinking agent (C),
The weight ratio of the water-absorbent resin (A) to the cross-linking agent (C) varies depending on the type of the water-absorbent resin (A) and the degree of crosslinking thereof, the performance target of the resulting modified water-absorbent resin particles of the present invention, and the like. And usually 100: (0.001-5), preferably 100: (0.001
To 3), particularly preferably 100: (0.01 to 2), most preferably 100: (0.05 to 1). By using the crosslinking agent (C) in the above range, the absorption rate of the water-absorbent resin particles can be further improved without lowering the absorption amount, and the gel strength can be increased, which is preferable.

The method of adding (B) [and the above-mentioned crosslinking agent (C) optionally used] to the particles (A) may be any method as long as a predetermined amount can be added. For example, a) direct blending of each component B) adding and mixing (B) at a high concentration (for example, 5 to 20% by weight) to (A) to prepare a master batch, and then adding (B) a predetermined amount C) a method of adding and mixing the masterbatch to (A) and mixing and mixing the emulsion of (B) with the particles of (A) so as to obtain d) a hydrophobic and / or hydrophilic organic solvent. (B)
A method of dispersing or dissolving [and optionally a cross-linking agent (C)] and adding / mixing to (A) particles, e) (B) [B] in a mixed solvent of a hydrophilic organic solvent such as alcohol and water. And a cross-linking agent (C) used together if necessary]
For example, a method of dissolving or dispersing and adding / mixing.

The apparatus used for adding (B) [and optionally the crosslinking agent (C) used together] to the particles (A) may be an ordinary mixer, for example, a cylindrical mixer, a screw mixer, or a screw mixer. Extruders, turbulizers, Nauta-type mixers, V-type mixers, ribbon-type mixers, double-arm kneaders, flow-type mixers, airflow-type mixers, rotating disk-type mixers,
Examples include a conical blender and a roll mixer.

The mixture obtained by the treatment described above differs depending on the presence or absence of the reactive functional unit of (B) [and optionally the crosslinking agent (C) used together] and the reactivity. Heating may be performed for the purpose of promoting the heat treatment. Further, the above mixing and heating may be performed simultaneously. The reaction is defined as "a water-absorbent resin (A)" and "(B) a modified silicone oil when a modified silicone oil reactive with (A) is used, and a crosslinking agent (C) optionally used together." It is a crosslinking reaction.

The heating temperature is usually 60 to 200 ° C., preferably 8
0-180 ° C. For this heating, a dryer or a heater such as a hot air dryer, a rotary drum dryer, a paddle dryer,
A disk heater, a fluidized bed dryer, a belt dryer, a Nauta heater, an infrared heater, and the like can be used.

The modified water absorbent resin particles for sanitary goods of the present invention include:
At any stage of this modification, finely divided silicon dioxide (D) can be added. By adding (D), the absorption rate can be further improved. Also, improvement in powder fluidity can be expected.

Examples of the silicon dioxide fine powder (D) include dry inorganic silica produced by hydrolyzing silicon tetrachloride in a flame obtained by burning oxygen and hydrogen at a high temperature.
d Silica ". In addition, silica with an alkyl group introduced by further reacting silanol groups on the surface of inorganic silica with monomethyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, etc. Specifically, the specific surface area is 50 to 500 m ³ /
In g, silicon dioxide having a primary particle size of 5 to 50 nm is exemplified.

Preferred silicon dioxide fine powder (D) is a so-called hydrophilic silicon dioxide having the above specific surface area and particle size and having a hydrophilicity of 70% or more. Here, the hydrophilicity is the weight ratio of silicon dioxide suspended colloidally in a mixed solution of water / methanol = 70/30 (weight ratio). As this value is smaller, the hydrophobicity becomes stronger, and what is generally called hydrophobic silica is silicon dioxide having a hydrophilicity of 0%.
When the hydrophobicity increases, the absorption rate of the water-absorbent resin particles tends to decrease depending on the amount of (B) added to (A), and therefore, hydrophilic silicon dioxide having a hydrophilicity of 70% or more is used. Preferably, it is used.

The amount when the silicon dioxide fine powder (D) is used is
It is usually 0.001 to 2% by weight, preferably 0.01 to 1 part by weight, based on the amount of (A). More preferably, the amount is smaller than the amount of (B) added to (A). By setting the amount of (D) to be in the above range, the absorption rate can be further improved, there is no problem of dust generation, and improvement in powder fluidity can be expected. As a method of adding the silicon dioxide fine powder (D), for example, a method in which (D) is added and mixed in advance to (A) particles, a method in which (D) is added and mixed in (B), (A) A method of adding (D) while mixing particles and (B), a method of adding and mixing (D) to a mixture of (A) particles and (B), and the like.

The modified water absorbent resin particles for sanitary goods of the present invention include:
Organic powders (eg, pulp powder, cellulose derivatives, natural polysaccharides, etc.) and inorganic powders (eg, zeolite, silica, alumina, bentonite, activated carbon, etc.) as extenders or additives within a range not to impair the effects of the present invention.
Antioxidants, preservatives, bactericides, surfactants, coloring agents, fragrances, deodorants, etc. can be added as required, and these amounts are usually based on the weight of the modified water absorbent resin particles.
10% by weight or less.

The modified water-absorbent resin particles for sanitary goods of the present invention are substantially water-insoluble resin particles, and the moisture-absorbing blocking rate, the dustiness, and the absorption characteristics can be controlled depending on the purpose of use. (At 40 ° C., 80% RH, after 3 hours) The moisture absorption blocking rate is usually 20% or less, preferably
It is 10% or less, the degree of dust is usually 10 cpm or less, preferably 5 cpm or less, and the initial absorption amount under pressure to physiological saline is 20 g / g or more, preferably 25 g / g or more. The upper limit of the initial absorption amount is not particularly limited, and the larger the larger, the better, but it is usually 50 g / g or less.

In addition, physiological saline is an aqueous solution of sodium chloride (concentration
0.85 to 0.95% by weight).

Therefore, the modified water-absorbent resin particles for sanitary goods of the present invention has almost no moisture-absorbing blocking even when used under high humidity, hardly any dust is generated at the time of making a paper diaper, etc. Because of the excellent absorption amount, the gel has a good dry feeling after water absorption and has a dry feel. Therefore, for example, when used in a disposable diaper or the like, a large amount of urine or the like can be quickly absorbed while enduring a load such as the weight of a baby, and the dry feeling on the disposable diaper surface after urination is improved.

Hereinafter, the present invention will be further described with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

<Examples 1 to 4 and Comparative Examples 1 to 7> In Examples 1 to 4 and Comparative Examples 1 to 7, the moisture absorption blocking ratio, the degree of dust, the initial absorption amount under pressure, and the absorption ratio under pressure were measured by the following methods. did. Hereinafter, unless otherwise specified,% indicates% by weight.

Moisture absorption blocking rate: 10 g of water-absorbent resin particles having a particle size of 20 mesh or less with a diameter of 5 cm
And placed in a constant temperature / humidity chamber at 40 ° C and a relative humidity of 80% for 3 hours. The water-absorbent resin particles after standing were lightly sieved with a 12-mesh wire net, and the weight of the resin that became 12 mesh or more after being blocked by moisture absorption was measured, and the moisture-absorbing blocking ratio was determined by the following formula.

Moisture absorption blocking rate (%) = (weight of resin of 12 mesh or more / total weight of resin particles after standing) x 100 Dust: Inside diameter of suction port of 1 liter suction bottle and sampling port of digital dust meter (manufactured by Shibata Science) Connect with a 7mm, 10cm long glass tube. 20 g of water-absorbent resin particles are dropped into the suction bottle from the upper mouth of the suction bottle using a funnel. The number of dusts generated per minute from the dropped water-absorbent resin particles is measured using a digital dust meter, and this value is referred to as the degree of dust [unit: cp
m (count per minute)].

Initial absorption amount and absorption capacity under pressure: 0.1 g of water-absorbent resin particles are placed in a cylindrical plastic tube (inner diameter 30 mm, height 60 mm) with a 250 mesh nylon mesh stuck on the bottom, and spread uniformly. Over 20
A weight having an outer diameter of 30 mm is placed so that the load becomes g / cm ² .

A plastic tube containing water-absorbing resin particles is immersed in a petri dish (diameter: 12 cm) containing 60 ml of physiological saline with the nylon mesh side facing down, and left. After 10 minutes and 60 minutes, the weight of the water-absorbent resin particles
Measure after minutes. The 10-fold value of the weight gained after 10 minutes is the initial absorption under pressure in physiological saline, 10 times the weight gained after 60 minutes.
The double value was defined as the absorption capacity under a physiological saline solution under pressure.

Example 1 Commercially available particulate water absorbent resin "Sunwet IM-5000D"
[Partial sodium neutralized salt of cross-linked polyacrylic acid, manufactured by Sanyo Chemical Industries, Ltd .; content of particles having a particle size of 10 to 1,000 μm is 9
9.9 weight or more] into a plastic bag and add amino-modified silicone oil [Shin-Etsu Chemical Co., Ltd. “KF-
880 "(surface tension: 21.3 dynes / cm; viscosity: 650 cps; average molecular weight: about 20,000)] was added and mixed well to obtain the modified water absorbent resin particles (a1) for sanitary goods of the present invention. Table 1 shows the performance measurement results of this product.

Example 2 Commercially available particulate water absorbent resin "Sunwet IM-5800"
[Surface crosslinked product of crosslinked polyacrylic acid partial sodium neutralized salt, manufactured by Sanyo Chemical Industries, Ltd .; content of particles having a particle size of 10 to 1,000 μm is 99.9% by weight or more] 100 g is put into a 2,000 ml juicer mixer. While stirring, epoxy-modified silicone oil [KF-10 manufactured by Shin-Etsu Chemical Co., Ltd.
1 "(surface tension: 25.2 dynes / cm; viscosity: 2,000 cps; average molecular weight: about 9,000)] was added and mixed well. The resulting mixture was heated at 150 ° C. for about 20 minutes to modify the present invention. The obtained water-absorbent resin particles for sanitary goods (a2) are shown in Table 1.

Example 3 Commercially available particulate water absorbent resin "Sunwet IM-1000"
[Partial sodium neutralized salt of starch / acrylic acid graft polymer, manufactured by Sanyo Chemical Industries, Ltd .; particle size: 10 to 1,000 μm
If the particle content of 99.9% by weight or more is placed in a juicer mixer having a capacity of 2,000 ml and stirring is continued, an epoxy-modified silicone oil [Made by Shin-Etsu Chemical Co., Ltd., "KF- 101 "] and 5 g of an aqueous methanol solution in which 2% by weight of ethylene glycol diglycidyl ether [" Denacol EX-810 ", manufactured by Nagase Kasei Kogyo Co., Ltd.] (-101 "corresponds to 0.3 part, and" EX-810 "corresponds to 0.1 part). 15 of the resulting mixture
Heat treatment was performed at 0 ° C. for about 20 minutes to obtain the modified water-absorbent resin particles (a3) for sanitary goods of the present invention. Table 1 shows the performance measurement results of this product.

Example 4 An epoxy-modified silicone oil [manufactured by Shin-Etsu Chemical Co., Ltd .;
22-163B "(surface tension: 21.0 dynes / cm; viscosity: 65 cps; average molecular weight: about 3,000)], and 5 g of an aqueous solution obtained by dissolving 6% by weight of a polyamine epichlorohydrin resin in a 30% by weight aqueous solution of a 3 mol adduct of ethylene oxide with methanol ( 0.1 part of "X-22-163B" and 0.3 part of polyamine epichlorohydrin resin were added to 100 parts of the water-absorbent resin particles, respectively, and mixed well.
For about 20 minutes to obtain the modified water absorbent resin particles (a4) for sanitary goods of the present invention. Table 1 shows the performance measurement results of this product.

Comparative Example 1 Commercially available “Sunwet IM-5000D” was used as it was as a comparative water-absorbent resin particle (b1). Table 1 shows the performance measurement results of this product.

Comparative Example 2 Commercially available "Sunwet IM-5800" was used as it was as a comparative water-absorbing resin particle (b2). Table 1 shows the performance measurement results of this product.

Comparative Example 3 Commercially available “Sunwet IM-1000” was used as it was as a comparative water absorbent resin particle (b3). Table 1 shows the performance measurement results of this product.

Comparative Example 4 Commercially available particulate water absorbent resin "Sunwet IM-5000D" 10
0.5 g of hydrophobic silica ("Aerosil-972") was added to 0 g to obtain comparative water-absorbent resin particles (b4). Table 1 shows the performance measurement results of this product.

Comparative Example 5 Commercially available particulate water absorbent resin "Sunwet IM-5000D" 10
To 0 g, 1.0 g of titanium oxide having a particle size of 30 μm was added to obtain comparative water-absorbent resin particles (b5). Table-Performance measurement results of this product
It is shown in FIG.

Comparative Example 6 Commercially available particulate water absorbent resin "Sunwet IM-5800" 100
5 g of distearyldimethylammonium chloride dissolved by heating to g, stirred at 80 ° C. for 10 minutes, and then added 0.5 g of polystyrene powder having a particle size of 20 μm, and then the comparative water-absorbent resin particles (b6) I got Table 1 shows the performance measurement results of this product.

Comparative Example 7 Commercially available particulate water absorbent resin "Sunwet IM-5800" 100
To 1 g, 1 g of stearic acid was added, heated to 80 ° C. to melt the stearic acid, and stirred at this temperature for 10 minutes. Then
After 3 g of silicon oxide was added thereto and mixed well, the mixture was cooled to room temperature to obtain comparative water-absorbent resin particles (b7). Table 1 shows the performance measurement results of this product.

From Table 1, the following is clear.

The modified water absorbent resin particles for sanitary goods of the present invention (a1)
As for (a4), the moisture absorption blocking ratio, dustiness, initial absorption amount under pressure and absorption capacity are dramatically improved as compared with the untreated water-absorbent resin particles (b1) to (b3).

Modified water absorbent resin particles (a1) to (a4) of the present invention
Is compared with the comparative water absorbent resin particles (b4) to (b7),
Excellent moisture absorption blocking ratio, dustiness, initial absorption under pressure and absorption capacity.

In addition, the water-absorbent resins (b4) to (b6) of the comparative examples have improved moisture-absorbing blocking rates as compared with the untreated water-absorbent resin particles (b1) to (b3), but the dustiness is rather low. Is getting worse. Furthermore, the initial absorption amount and absorption capacity under pressure are all worse for the comparative water-absorbent resin particles (b4) to (b7) than for the untreated water-absorbent resin (b1) to (b3).

<Examples 5 to 16, Comparative Examples 8 to 12> In Examples 5 to 16 and Comparative Examples 8 to 12, the normal pressure absorption amount, the pressure absorption amount, the absorption speed, the permeability, and the gelation time of the water-absorbent resin particles are as follows. It was measured by the following method.

Normal pressure absorption: 500 g of water-absorbent resin particles in a tea bag (length: 20 cm, width: 10 cm) made of 250 mesh nylon mesh
After being immersed in 1 liter of physiological saline (a 0.9% aqueous solution of sodium chloride) for 30 minutes, it was pulled up and drained for 15 minutes, and the increased weight was measured.

Pressure absorption capacity: 0.1 g of water-absorbent resin particles are placed in a cylindrical plastic tube (inner diameter 30 mm, height 60 mm) with a 250-mesh nylon mesh stuck on the bottom, spread evenly, and 20 g / cm on this resin
A weight with an outer diameter of 30 mm is placed so that the load becomes ² . A plastic tube containing water-absorbent resin particles is immersed in a petri dish (diameter: 12 cm) containing 60 ml of physiological saline for 30 minutes with the nylon mesh side facing downward. The value of 10 times the weight gained after 30 minutes was defined as the pressure absorption.

Absorption speed: Put 50ml of physiological saline and magnetic rotor (almost cylindrical, 30mm in length, 8mm in diameter at the center and 7mm in diameter at both ends) into a 100ml beaker, and use a magnetic stirrer to move the magnetic rotor. While rotating at 600 rpm, 2.0 g of the water-absorbing resin particles were charged, and the time from immediately after the charging to the stop of the rotation of the rotor was measured and defined as an absorption rate.

Permeability: 2 g of water-absorbent resin particles are placed in a 50 ml beaker, and then 30 ml of physiological saline is gently added so that the water-absorbent resin particles are not diffused. The permeation state was visually determined. The criteria are as follows.

：: No formation of mamako, good permeability ○: Good permeability, but slight formation of mamaco △: Slightly poor permeability and generation of mamaco ×: Poor permeability, generation of mamako gel Aging time: Put 2g of water-absorbent resin particles into a 50ml beaker, and then gently add 30ml of physiological saline so as to prevent diffusion of the water-absorbent resin particles. The time was measured, and this value was defined as the gel time.

Comparative Example 8 In a glass reaction vessel having a capacity of 1 liter, 95 g of sodium acrylate, 27 g of acrylic acid, 0.3 g of N, N'-methylenebisacrylamide and 430 g of deionized water were charged, and the temperature of the content was stirred and mixed. It was kept at 5 ° C. After flowing nitrogen into the contents to reduce the amount of dissolved oxygen to 1 ppm or less, 1 g of a 1% aqueous solution of hydrogen peroxide and 1 g of a 0.3% aqueous solution of ascorbic acid are added to initiate polymerization, and polymerization is performed for about 5 hours. Thus, a hydrogel polymer was obtained. The hydrogel polymer was dried with hot air at 130 to 150 ° C. and pulverized to a particle size of 850 μm or less to obtain water-absorbent resin particles (b9). (B8) contained 7.2% of fine particles having a particle size of 105 μm or less, and 1.0% of fine particles having a particle size of 45 μm or less. Table 2 shows the performance measurement results of the water absorbent resin particles (b8).

Comparative Example 9 While stirring 100 g of the water-absorbent resin particles (b8) obtained in Comparative Example 8 at a high speed, 1 g of a 10% aqueous solution of ethylene glycol diglycidyl ether was sprayed uniformly on (b8).
Heat treatment was performed for 0 minutes to obtain water-absorbent resin particles (b9) whose surface was crosslinked. The particle size distribution of (b9) was almost the same as (b8), but the content of fine particles having a particle size of 105 μm or less was 6.4%, and the content of fine particles having a particle size of 45 μm or less was 0.9%. For comparison, the performance measurement results of the water absorbent resin particles (b9) are shown in Table 2.

Comparative Example 10 The water-absorbent resin particles (b8) obtained in Comparative Example 8
Fine particles having a size of 5 μm or less were removed to obtain water-absorbent resin particles (b10). Table 2 shows the performance measurement results of the water absorbent resin particles (b10).

Comparative Example 11 Acrylic acid 100 was placed in a 1-liter glass reaction vessel.
g, 0.3 g of tetraallyloxyethane and 350 of deionized water
g, and the content was kept at 5 ° C. while stirring. After flowing nitrogen into the contents to reduce the amount of dissolved oxygen to 1 ppm or less, 1 g of a 1% aqueous solution of hydrogen peroxide and 1 g of a 0.3% aqueous solution of ascorbic acid are added to initiate polymerization, and polymerization is performed for about 5 hours. A hydrogel polymer was obtained.

While kneading this hydrogel polymer with an extruder equipped with a perforated plate, 116 g of a 35% aqueous sodium hydroxide solution was added and kneaded uniformly to obtain a hydrogel having about 73 mol% of acrylic acid neutralized. A polymer was obtained. The hydrogel polymer was dried with a drum dryer having a surface temperature of 180 ° C. and pulverized to a particle size of 850 μm or less to obtain water-absorbent resin particles (b11). (B11) contained 5.2% of fine particles having a particle size of 105 μm or less, and 0.8% of fine particles having a particle size of 45 μm or less. Table 2 shows the performance measurement results of the water absorbent resin particles (b11).

Comparative Example 12 In a 200 ml flask, 65.4 g of acrylic acid, deionized water
While charging 78.6 g, while cooling to 20 to 30 ° C., 56.0 g of a 48% aqueous sodium hydroxide solution was gradually dropped with stirring to neutralize 74 mol% of acrylic acid. N, N '
After dissolving 0.2 g of methylenebisacrylamide and then adding 0.1 g of potassium persulfate and dissolving at room temperature, the amount of dissolved oxygen in the solution was reduced to 1 ppm or less by flowing nitrogen gas.

N-liter in a 1 liter flask equipped with a reflux condenser
Charge 400 g of hexane and 3 g of sorbitan monostearate
After dissolving, the amount of dissolved oxygen in the solution was reduced to 1 ppm or less by flowing nitrogen gas. Then, the temperature is maintained at about 60 ° C. by a warm bath, and while stirring, the above-mentioned aqueous solution of the monomer containing potassium persulfate is added dropwise to carry out the polymerization for about 3 hours, and the polymerization is further continued for 2 hours under the relaxed condition. Thereby, a dispersion liquid of the pearl-like hydropolymer was obtained. The hydrated polymer was separated from this polymer dispersion by filtration and further subjected to centrifugal dehydration to obtain a pearl-shaped hydrated polymer. 90 ~
Drying under reduced pressure at 95 ° C. gave pearl-like water-absorbent resin particles (b12) having a particle size of 850 μm or less. (B12) has a particle size of 105μ
6.4% of fine particles with a particle size of 45 μm or less.
The ratio of fine particles having a particle size of m or less was 0.9%. Table 2 shows the performance measurement results of the water absorbent resin particles (b12).

Example 5 100 parts of the water absorbent resin particles (b8) obtained in Comparative Example 8,
Dimethyl silicone oil “Shin-Etsu Silicone KF96A-10
0 "[manufactured by Shin-Etsu Chemical Co., Ltd .; surface tension: 20.9 dynes / cm; viscosity: 100 cps; average molecular weight: about 6,000] 0.05 part was placed in a V-type mixer, and mixed with the water-absorbent resin particles (b8) for 20 minutes. The modified water absorbent resin particles (a5) for sanitary articles of the present invention having substantially the same particle size distribution were obtained, and the performance measurement results of the water absorbent resin particles (a5) are shown in Table 2.

Examples 6 and 7 In the same manner as in Example 5, except that the addition amount of the dimethyl silicone oil “Shin-Etsu Silicone KF96-100” to the water-absorbent resin particles (b8) was changed to 0.01% and 0.1%, respectively. The modified water absorbent resin particles (a6) and (a7) for sanitary goods of the present invention were obtained. Table 2 shows the performance measurement results of these water absorbent resin particles.

Examples 8 to 10 In Example 5, instead of "Shin-Etsu Silicone KF96A-100", dimethyl silicone oil "Shin-Etsu Silicone KF96-50" manufactured by Shin-Etsu Chemical Co., Ltd. [surface tension: 20.8 dynes / cm; viscosity: 50 cps Average molecular weight about 3,500], dimethyl silicone oil "Shin-Etsu Silicone KF96-350" [surface tension
21.1 dynes / cm; viscosity 350 cps; average molecular weight about 15,000], dimethyl silicone oil "Shin-Etsu Silicone Oil KF54"
[Surface tension 25.2 dynes / cm; viscosity 400 cps; average molecular weight about 16,
000] in the same manner as in Example 5, except that the modified water-absorbent resin particles (a8) and (a9) for sanitary goods of the present invention were used.
And (a10) were obtained. Table 2 shows the performance measurement results of these water absorbent resin particles.

Examples 11 and 12 In Example 5, instead of "Shin-Etsu Silicone KF96-100", dimethyl silicone oil "Shin-Etsu Silicone KF96-5" (manufactured by Shin-Etsu Chemical Co., Ltd.) (surface tension: 19.7 dynes / cm; viscosity) 5cps; average molecular weight about 100), dimethyl silicone oil "Shin-Etsu Silicone KF96-3000" (surface tension 21.3
(Dyne / cm; viscosity: 3,000 cps; average molecular weight: about 40,000) in the same manner as in Example 5 to obtain modified water-absorbent resin particles (a11) and (a12) for sanitary goods of the present invention. . Table 2 shows the performance measurement results of these water absorbent resin particles.

Example 13 To the water-absorbent resin particles (a5) obtained in Example 5, 0.02% of silicon dioxide having a hydrophilicity of 100% (“Reloseal QS-102”; manufactured by Tokuyama Soda Co., Ltd.) was added, and the mixture was uniformly mixed. The mixture was mixed to obtain the modified water-absorbent resin particles (a13) for sanitary articles of the present invention. Table 1 shows the performance measurement results of the water-absorbent resin particles (a13).
It is shown in FIG.

Examples 14 to 16 In Example 5, instead of the water absorbent resin particles (b8),
The modified water-absorbent resin particles for sanitary goods of the present invention were prepared in the same manner as in Example 1 except that the water-absorbent resins (b9), (b10) and (b12) were used, respectively (a14), (a15) and (A16) was obtained. Table 2 shows the performance measurement results of these water absorbent resin particles.

As can be seen from Table 2, the modified water-absorbent resin particles for sanitary ware of the present invention and the composition containing these particles are referred to as a normal pressure absorption amount and a pressure absorption amount as compared with the corresponding comparative examples. The absorption rate is increased, the permeability is excellent, and the gel time is dramatically improved without deteriorating the performance.

INDUSTRIAL APPLICABILITY The modified water absorbent resin particles for sanitary goods of the present invention have improved absorption speed, moisture absorption blocking properties, and improved dust generation, and have a water absorbent resin. The absorption performance is also maintained or improved.

1) Improvement of absorption rate It shows a high absorption rate not only for water but also for human body effluents such as salt solution, urine, and blood. As compared with the water-absorbing resin particles before the treatment with the organic polysiloxane, the absorption rate is about 1 /
It is improved to 2 to 1/4.

After the liquid uniformly wets the surface of the water-absorbent resin particles, the liquid penetrates into the inside of the particles, so that the water-absorbent resin particles quickly gel.

Even when many fine particles having a small particle diameter are contained as a water-absorbing resin, a high absorption rate is exhibited.

2) Improvement of moisture absorption blocking property and dust generation property Since the water-soluble organic polysiloxane is efficiently fixed or adhered to the surface of the water absorbent resin particles, the moisture absorption blocking rate is low. Therefore, even when used in a high-humidity environment, the water-absorbent resin does not block and is excellent in workability.

Since the organic polysiloxane is in a liquid state, unlike other methods of adding a hydrophobic fine powder or the like, the degree of dust is reduced by a wet action. Therefore, even if the water-absorbent resin particles are handled in large quantities, the fine particles are not scattered, the working environment is improved, and the number of dust suction machines for the workers is reduced.

Since the scattering is small, the loss rate of the water-absorbing resin particles in a disposable diaper or the like is reduced, and the productivity is improved.

3) Maintenance or improvement of absorption performance Even after the modification with the organic polysiloxane, the absorption performance is equal to or higher than that before the modification.

In particular, when an organic polysiloxane having reactivity with the water-absorbent resin before modification is used, in order to crosslink the vicinity of the surface of the water-absorbent resin, the initial absorption amount under pressure and the absorption capacity are increased for the water-absorbent resin particles before treatment. Improve compared. Therefore, when used as a disposable diaper, it can withstand loads such as the weight of a baby and can quickly absorb a large amount of urine, and the amount of urine returned is low. Shows feel.

Due to the above effects, the modified water-absorbent resin particles for sanitary goods of the present invention include disposable diapers (disposable diapers for children and adult disposable diapers), sanitary napkins, incontinence pads, breast milk pads, surgical underpads, It can be used particularly suitably for sanitary articles such as pet sheets and absorbent materials.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI C08G 81/02 C08J 3/12 Z C08J 3/12 3/14 3/14 3/16 3/16 C08L 33/02 C08L 33 / 02 101/14 101/14 (72) Inventor Masanori Koike 11 at Hitotsubashi Nohonmachi, Higashiyama-ku, Kyoto-shi, Kyoto 1 Inside Sanyo Chemical Industries Co., Ltd. 1. Sanyo Kasei Kogyo Co., Ltd. (56) References JP-A-6-299144 (JP, A) JP-A-5-70625 (JP, A) JP-A-7-88171 (JP, A) JP-A-61- 264006 (JP, A) JP-A-61-211305 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) A61F 13/53 A61L 15/00 B01J 20/26 C08L 101/14

Claims (8)

(57) [Claims] 1. A crosslinked polymer of an ethylenically unsaturated monomer having acrylic acid and / or an acrylate as a main structural unit, and particles of the water-absorbent resin (A) which is substantially insoluble in water, The modified water-absorbent resin particles for sanitary goods treated with the liquid organic polysiloxane (B) at room temperature, wherein (A) and (B) are mixed and / or reacted, Among the particles, the content of particles having a particle size of 10 to 1,000 μm is 95% by weight or more, and the weight ratio (A) / (B) is 100 / (0.001 to 5). Resin particles. 2. The viscosity of (B) at 25 ° C. is 10 to 20,000 cs.
The modified water-absorbent resin particles for sanitary goods according to claim 1, wherein the particle diameter is t and the surface tension is 18 to 30 dynes / cm. 3. The method according to claim 1, wherein (B) has a carboxylic acid group and / or
Or a modified silicone oil having at least one functional group capable of reacting with a carboxylate group.
Item 3. The modified water absorbent resin particles for sanitary articles according to item 2 or 2. 4. The modified water absorbent resin particles for sanitary goods according to claim 3, wherein (B) is an amino-modified silicone oil or an epoxy-modified silicone oil. 5. The modified water absorbent resin particles for sanitary goods according to claim 1, wherein the average molecular weight of (B) is 1,000 or more. 6. The compound (A) can react with a carboxylic acid group and / or a carboxylic acid group in the molecule before, simultaneously with, or after the treatment with (B). The modified water absorption for sanitary goods according to claim 1 or 2, wherein the surface of the particles of (A) is further cross-linked with a cross-linking agent (C) having at least two functional groups. Resin particles. 7. The modified water absorbent for sanitary goods according to claim 1, wherein 0.001 to 2% by weight of fine powder of silicon dioxide (D) is added to (A). Resin particles. 8. Absorption characteristics in which the moisture absorption blocking ratio at a relative humidity of 80% (40 ° C.) is 20% or less, the dustiness degree is 10 cpm or less, and the initial absorption amount under pressure to physiological saline is 20 g / g or more. The modified water-absorbent resin particles for sanitary goods according to claim 1 or 2, having the following.