JPH07316444A - Water-absorbing resin composition and urine-absorbing article - Google Patents

Abstract

PURPOSE:To obtain a water-absorbing resin compsn. excellent in the resistance to urine and useful for urine-absorbing articles such as a paper diaper, a portable toilet, a pet sheet, and sand for a cat by adding specific additives to a water-absorbing resin. CONSTITUTION:The objective compsn. comprises 100 pts.wt. water-absorbing resin (esp. pref. one produced mainly from acrylic acid), an iron-chlorophyllin salt and/or a copper-chlorophyllin salt (esp. pref. a sodium salt) pref. in an amt. of 0.01-5 pts.wt., and inorg. particles (esp. pref. fine silica particles) pref. in an amt. of 0.01-5 pts.wt.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a water absorbent resin composition and a urine absorbing article. More specifically, it relates to a water absorbent resin composition having excellent urine resistance and a urine absorbent article.

[0002]

2. Description of the Related Art In recent years, a water-absorbent resin has been developed as a polymer that absorbs a large amount of water and gels, and is mainly used in the field of sanitary materials such as disposable diapers and sanitary napkins, as well as other fields such as agriculture and forestry, civil engineering, and food. Widely used in the fields, medical field, housing field, etc.

Therefore, many water-absorbent resins have been developed up to now, for example, crosslinked polyacrylic acid partially neutralized products (US Pat. Nos. 4,654,039 and 4,286082).
No.), a hydrolyzate of a starch-acrylonitrile graft polymer (US Pat. No. 3,618,815), a starch-acrylic acid graft polymer (US Pat. No. 4,076,663), a saponified product of a vinyl acetate-acrylic acid ester copolymer (US Pat. No. 4,124,748). No.), an isobutylene-maleic anhydride copolymer (US Pat. No. 4,389,513), and an acrylonitrile copolymer hydrolyzate (US Pat. No. 3935099).
No.), a hydrolyzate of an acrylamide polymer or copolymer (US Pat. No. 3,959,569), a cross-linked copolymer of 2-acrylamido-2-methylpropanesulfonic acid and acrylic acid (European patent No. 068189), carboxymethyl cellulose salt. Crosslinked product (US Pat. No. 4,650,716,
No. 4,689,408), crosslinked polymers of cationic monomers, and crosslinked polymers of 2-sulfoethyl methacrylate are known.

However, although it is a water-absorbent resin which shows a stable high water-absorption capacity for pure water and physiological saline over a long period of time, the water-absorbent resin swollen with urine deteriorates and collapses with time. The water-absorbent resin is currently used as a urine absorbing article such as paper diapers, simple toilet bowls, incontinence pads, pet excretion treatment agents, etc. There is a strong demand for improved stability of swelling gel with urine. As a means to improve the durability of the water-absorbent resin to urine (hereinafter referred to as urine resistance), a highly cross-linked water-absorbent resin can be made by increasing the amount of cross-linking agent at the time of polymerization, but the water absorption capacity is greatly reduced. However, it is disadvantageous in terms of cost.

Therefore, a method for imparting urine resistance by adding a specific additive to the water-absorbent resin has been proposed. For example, a method of adding an oxygen-containing reducing inorganic salt (Japanese Patent Laid-Open No. 63-11).
8375, US Patent 4972019, US Patent 48
No. 63989), a method of adding an antioxidant (Japanese Patent Laid-Open No. Sho 6-62).
3-127754), a method of adding an oxidizing agent (JP-A-63-153060), a method of adding a sulfur-containing reducing agent (JP-A-63-272349), and a method of adding a water-soluble phosphorus compound ( JP-A-64-33158) and the like are known. Further, a method for imparting urine resistance by using a specific compound at the time of polymerization is also proposed, for example, a method of polymerizing in the presence of a specific amount of a chain transfer agent and a specific amount of a cross-linking agent (JP-A-2-255804, JP-A-3-179008
And European Patent No. 0372981) and a method of polymerizing in the presence of a water-soluble phosphoric acid compound (JP-A-5-97929).
Is also known. However, it was difficult to say that any of the methods for improving urine resistance is still perfect in its effect and convenience.

[0006]

The present invention has been made in view of the above situation. Therefore, an object of the present invention is to impart excellent urine resistance to a water absorbent resin by a very simple method.

[0007]

Means and Actions for Solving the Problems As a result of intensive investigations by the present inventors to solve the above problems, a composition comprising iron chlorophyllin salt and / or copper chlorophyllin salt, inorganic particles and a water-absorbent resin, They have found that they exhibit excellent characteristics of urine resistance, and have completed the present invention.

That is, the present invention relates to a water absorbent resin composition comprising an iron chlorophyllin salt and / or a copper chlorophyllin salt, inorganic particles and a water absorbent resin, and a urine absorbing article containing the water absorbent resin composition. Is.

The present invention will be described in more detail below.

The water-absorbent resin used in the present invention is a known water-absorbent resin which absorbs a large amount of water in water and swells to form a hydrogel. For example, a polyacrylate cross-linked product, starch-acrylonitrile graft Polymer hydrolyzate, starch-acrylic acid (salt) graft polymer, vinyl acetate-acrylic acid ester copolymer saponification product, 2-acrylamido-2-methylpropanesulfonic acid (salt) polymer, polyacrylamide cross-linking Examples thereof include a hydrolyzate of the body and a neutralized product of isobutylene maleic anhydride copolymer.

Among these water-absorbent resins, acrylic acid (salt), β-acryloyloxypropionic acid (salt), methacrylic acid (salt), and 2 are those in which the water-absorbent resin composition of the present invention exerts more effects. -(Meth) acryloylethanesulfonic acid (salt), 2- (meth) acrylamido-2-methylpropanesulfonic acid (salt), methoxypolyethylene glycol (meth) acrylate, N, N-
Dimethylaminoethyl (meth) acrylate and its quaternary salts, water-absorbent resin polymerized with an unsaturated monomer such as acrylamide as a main component is exemplified, and more preferably,
It is a water-absorbent resin whose main component is acrylic acid. Incidentally, these water absorbent resins may be a copolymer with a hydrophobic unsaturated monomer such as butadiene, isobutene, ethylene, propylene, stearyl (meth) acrylate,
It may be a graft polymer.

When the water absorbent resin has an acid group such as a carboxyl group, the acid group is preferably 30 to 100.
Mol% neutralization, more preferably 40 to 95 mol% neutralization, and even more preferably 50 to 80 mol% neutralization. Examples of the basic substance used before or after the polymerization for neutralization include carbonic acid (hydrogen) salts, alkali metal hydroxides, ammonia, organic amines and the like.

There are no particular restrictions on the cross-linking method for producing the water-absorbent resin, but it is preferable to add a predetermined amount of the internal cross-linking agent in advance and carry out the polymerization. Examples of the internal crosslinking agent used include N, N′-methylenebisacrylamide, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, Trimethylolpropane di (meth) acrylate,
Polyethylene glycol di (β-acryloyloxypropionate), poly (meth) allyloxy alkane, glycerin acrylate methacrylate, (poly) ethylene glycol diglycidyl ether, (poly) ethylene glycol, glycerin, pentaerythritol, ethylenediamine, polyethyleneimine, etc. One or two
One or more species are exemplified, but a polymerizable internal crosslinking agent is more preferable. The amount used is preferably 0.005 to 5 mol% and more preferably 0.01 to 1 mol% with respect to the monomer.

The polymerization of the above-mentioned monomer in the present invention can be carried out by bulk polymerization or precipitation polymerization, but it is usually preferable to use the solution of water or an aqueous liquid as the monomer. The concentration of the monomer is not particularly limited to exceed the saturation concentration, but it is usually 20
It is preferably in the range of wt% to saturated concentration. In addition,
At the time of polymerization, various hydrophilic polymers such as starch, cellulose, polyvinyl alcohol, polyethylene glycol, and cross-linked polyacrylates, and water-soluble chain transfer agents such as hypophosphorous acid (salt) may be added.

The method of polymerizing the above-mentioned monomers is not particularly limited, but polymerization with a radical polymerization initiator is preferred.
Examples of the radical polymerization method used include known polymerization methods such as aqueous solution polymerization, reverse phase suspension polymerization, reverse phase emulsion polymerization, precipitation polymerization, bulk polymerization and the like. Turbid polymerization is particularly preferred. Further, a fibrous base material or an inorganic substance may be allowed to coexist at the time of polymerization to form a water-absorbent composite.

The radical polymerization initiator used is
Known polymerization initiators such as sodium persulfate, t-butyl hydroperoxide, hydrogen peroxide, 2,2′-azobis (2-amidinopropane) dihydrochloride are used,
Further, there is no limitation on the combined use of these initiators and a reducing agent such as a sulfurous acid (hydrogen) salt or L-ascorbic acid, or the combined use of ultraviolet rays. The amount of these initiators and reducing agents used is usually 0.001 to 2 mol% based on the monomers.

Further, the gelled polymer after polymerization is optionally dried depending on the use and the solid content after polymerization. As the drying method, for example, known drying methods such as hot air drying, infrared drying, microwave drying, drum dryer drying, azeotropic dehydration in a hydrophobic organic solvent are used without limitation, but usually, these methods are used. , Solid content of 60% or more,
Furthermore, it is preferable to dry to 90% or more.

Further, the particle size may be adjusted by further pulverizing or granulating after polymerization or drying. For example, when a powdery water absorbent resin is intended, the average particle size is 10 to 2000 μm.
m, more preferably 100 to 1000 μm, most preferably 300 to 600 μm, and the particle size distribution is preferably narrow.

Further, the vicinity of the surface of these water-absorbent resins may be further cross-linked, or a reducing agent such as a sulfurous acid (hydrogen) salt or a surfactant may be added. A known method can be used without limitation as a method for crosslinking the vicinity of the surface of the water absorbent resin, but it is usually carried out by adding a surface crosslinking agent of a polyhydric alcohol or a polyvalent glycidyl to the vicinity of the surface of the particle.

The present invention is achieved by using the water absorbent resin as described above as a composition of iron chlorophyllin salt and / or copper chlorophyllin salt and inorganic particles.

The iron chlorophyllin salt or copper chlorophyllin salt used to obtain the composition of the present invention includes:
Examples thereof include salts with inorganic bases such as sodium and potassium, or organic bases such as basic amino acids. Above all, it is preferable to use iron chlorophyllin sodium or copper chlorophyllin sodium.

When both the iron chlorophyllin salt and the copper chlorophyllin salt are used, the mixing ratio may be arbitrary. The effects of the present invention are sufficiently exhibited even if either iron chlorophyllin salt or copper chlorophyllin salt is used alone.

In the present invention, the mixing ratio of the water-absorbent resin and the iron chlorophyllin salt and / or copper chlorophyllin salt alone or in a mixture is appropriately determined depending on the durability of the water-absorbent resin to be used, its application, use time, etc. Normal,
The total amount is 0.005-1 per 100 parts by weight of the water absorbent resin.
The amount is 0 parts by weight, preferably 0.01 to 5 parts by weight, more preferably 0.05 to 0.1 parts by weight. When the ratio of the total amount of iron chlorophyllin salt or copper chlorophyllin salt is less than 0.005 parts by weight, the urine resistance of the resulting water absorbent resin composition is low and the effect may be weakened in a relatively short time. When the proportion exceeds 10 parts by weight, excellent urine resistance is exhibited for a long time, but the resulting water-absorbent resin composition becomes extremely uneconomical and the degree of coloring of the resin becomes large, which is not preferable.

Examples of the inorganic particles used to obtain the composition of the present invention include water-insoluble fine powders such as silicon dioxide, titanium dioxide, aluminum oxide, zeolite, kaolin, hydrotalcite, bentonite and sepiolite. Of these, one kind or two or more kinds can be used. Particularly in the present invention, it is preferable to use fine particle silica.

The particle size of these inorganic fine particle powders is 10
00 μm, preferably 50 μm or less, more preferably 1
It is 0 μm or less.

In the present invention, the mixing ratio of the water absorbent resin and the inorganic particles is usually 0.005 to 10 parts by weight, preferably 0.01 to 5 parts by weight, per 100 parts by weight of the water absorbent resin.

The method for obtaining the composition of the present invention is not particularly limited, and the iron chlorophyllin salt and / or copper chlorophyllin salt and the inorganic particles can be mixed with the water absorbent resin simultaneously or individually. Examples of the mixing method include a dry mixing method, a method of further adding water, a binder, a cross-linking agent, etc. after the dry mixing, and an aqueous solution or dispersion solution of an iron chlorophyllin salt and / or a copper chlorophyllin salt being sprayed, impregnated or applied. Examples of the method include a method of mixing after mixing by means and a method of drying as needed, a method of mechanically kneading with a meat chopper or a kneader, a method of supporting after supporting on a fiber base material or an inorganic base material, and the like. In these methods, the water-absorbent resin to which the iron chlorophyllin salt and / or the copper chlorophyllin salt alone or a mixture and the inorganic particles are added may be a swollen gel, may be in a dry state, or may be cyclohexane. It may be in a dispersed state in an inert solvent. Furthermore, the mixed state of these and the water absorbent resin may be uniformly mixed inside the particles of the water absorbent resin, or may be mixed in the vicinity of the particle surface,
Although they may be mixed in a non-contact state with each other via another substrate, it is more preferable that they are mixed in the vicinity of the surface of the water-absorbent resin particles. Further, when mixed with the water absorbent resin, it may be mixed with a natural or synthetic fibrous substance or a water absorbent resin in which various surfactants coexist.

Even when only these iron chlorophyllin salt and / or copper chlorophyllin salt is mixed with the water-absorbent resin, the urine resistance is improved, but this alone does not give the urine resistance sufficiently effective for practical use. difficult. On the other hand, a mixture of only inorganic particles and a water-absorbent resin has no effect on urine resistance, and only when the iron chlorophyllin salt and / or copper chlorophyllin salt of the present invention and the inorganic particles are present at the same time, a remarkable urine resistance It is possible to improve the sex. Assuming its action, the addition of the inorganic particles suppresses the blocking between the water-absorbent resin gel particles and sufficiently maintains the independence of the gel particles. Therefore, the iron chlorophyllin salt and / or the copper chlorophyllin salt act efficiently with the components that cause deterioration in urine, and the excellent urine resistance due to the physical and chemical synergistic effect of these salts and the inorganic particles. It is considered that the effect can be obtained.

Further, the water-absorbent resin composition of the present invention is not only not only urine-resistant but also more excellent without deteriorating the deodorizing and antibacterial action which the iron chlorophyllin salt and / or the copper chlorophyllin salt originally have. It can be effectively used for various urine absorbing articles such as diapers, paper diapers, incontinence pads, portable toilets, pet sheets, and cat sand.

[0030]

The water-absorbent resin composition of the present invention comprising iron chlorophyllin salt and / or copper chlorophyllin salt, inorganic particles and water-absorbent resin exhibits excellent urine resistance, and the paper of the present invention using the same is used. Urine-absorbing articles for diapers, portable toilets, pet sheets, cat sand, etc. are suitable for use because they have urine resistance as well as deodorant and antibacterial effects.

[0031]

EXAMPLES The present invention will be described below with reference to examples.
The scope of the invention is not limited to only these examples.

(Production Example 1) Neutralization rate of 75 mol% and concentration of 37
% Partially Neutralized Acrylic Acid Sodium Salt Aqueous Solution 5500
1.36 g of trimethylolpropane triacrylate as an internal cross-linking agent (0.02 mol% with respect to the monomer) was dissolved in g, and an internal volume of 10 L was added to the jacketed stainless steel double-armed type Natsuka with two sigma type blades. Nitrogen was purged in a reactor with a lid on the machine (kneader). Then
While stirring the kneader blade, 13.8 g of a 20% sodium persulfate aqueous solution and 11.5 g of a 1% L-ascorbic acid aqueous solution were added as polymerization initiators, and polymerization was carried out for 60 minutes to obtain the resulting finely divided hydrogel. Polymer at 150 ° C
After drying with hot air for 60 minutes, the dried product was further pulverized with a vibration mill and classified to a particle size of 75 μm to 850 μm to obtain a white water-absorbent resin (1). Water absorbent resin (1)
Its absorption capacity was 54 times.

Example 1 100 g of the water absorbent resin (1) obtained in Production Example 1 was mixed with 0.1 g of sodium iron chlorophyllin.
g and 0.5 g of fine particle silica were directly added and mixed by a dry method to obtain an off-white powder composition (1). The water absorption resin composition was evaluated for urine resistance by the following method. The results are shown in Table 1.

(Evaluation method of urine resistance) Artificial urine containing 0.005% by weight of L-ascorbic acid (Artificial urine composition: Urea 9
5 g, sodium chloride 40 g, magnesium sulfate 5 g,
2 g of each water-absorbent resin composition was swelled 25 times in a 100 ml plastic container with a lid using 5 g of calcium chloride and 4855 g of ion-exchanged water, and left for a predetermined time in an atmosphere at a temperature of 37 ° C. and a relative humidity of 90%. . 16 hours, 20
The appearance of the swollen gel after the lapse of time was visually observed, and the degree of urine deterioration of the water absorbent resin was quantified by the fluidity when the container was tilted 90 degrees.

Example 2 A green-white water-absorbent resin composition (2) was obtained in the same manner as in Example 1 except that sodium chlorophyllin sodium was used instead of iron chlorophyllin sodium. The results of the same urine resistance evaluation are shown in Table 1.

Comparative Example 1 Water absorbent resin (1) of Example 1
Table 1 shows the results of similarly evaluating the urine resistance of the comparative water-absorbent resin composition (1), which is the only one.

Comparative Example 2 A comparative water absorbent resin composition (2) was obtained in the same manner as in Example 1 except that iron chlorophyllin sodium was not used. Table 1 shows the results of the similar evaluation of these physical properties.

(Comparative Example 3) An off-white comparative water-absorbent resin composition (3) was obtained in the same manner as in Example 1, except that fine particle silica was not used. Table 1 shows the results of the similar evaluation of these physical properties.

Comparative Example 4 A green-white comparative water-absorbent resin composition (4) was obtained in the same manner as in Example 2, except that fine particle silica was not used. Table 1 shows the results of the similar evaluation of these physical properties.

[0040]

[Table 1]

Claims (4)

[Claims] 1. A water absorbent resin composition comprising an iron chlorophyllin salt and / or a copper chlorophyllin salt, inorganic particles and a water absorbent resin. 2. The composition according to claim 1, wherein the inorganic particles are fine particle silica. 3. An iron chlorophyllin salt and / or a copper chlorophyllin salt is added to 100 parts by weight of the water absorbent resin.
The composition according to claim 1, wherein the content is 01 to 5 parts by weight and the amount of the inorganic particles is 0.01 to 5 parts by weight. 4. A urine absorbing article containing the water absorbent resin composition according to claim 1.