JPH06322179A - Salt-resistant absorbent composition - Google Patents

Abstract

PURPOSE:To provide the subject composition composed of a water absorbable resin and a sulfonic acid group-containing anionic surfactant, excellent in water absorption from a saline solution or an aqueous solution of a polyvalent ion, capable of ready production and applicable to wide use. CONSTITUTION:The objective composition is composed of (A) 100 pts.wt. water absorb resin (preferably a carboxyl group-containing starch-acrylonitrile copolymer, etc.) and (B) 1 to 300 pts.wt., preferably 5 to 150 pts.wt. sulfonic acid group-containing anionic surfactant (preferably, e.g. sodium lauryl sulfoacetate). This composition is produced recommendably by blending the component (A) with the component (B) or by adding the component (B) during the process for production of the component (A). In addition, the shape of the component (A) is preferably a powder having a particle size distribution that particles of >=90wt.% are 0.1 to 0.9mm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a salt-resistant absorbent composition having excellent water absorption performance for aqueous salt solutions.

[0002]

2. Description of the Related Art Heretofore, a hydrophilic cross-linked polymer called a water-absorbent resin has been known as a water-absorbing agent having an absorbing ability for an aqueous liquid. Examples of these water absorbent resins include starch-acrylic acid salt copolymers, crosslinked polyacrylic acid salts, crosslinked copolymers of acrylic acid and its salts with other monomers, and isobutylene-maleic anhydride copolymers. Various resins such as cross-linked polymers, polyvinyl alcohol- (meth) acrylic acid copolymers, modified cellulose derivatives, modified polyethylene oxide, modified polyvinyl alcohol are known, and are mainly used for sanitary materials such as disposable diapers and sanitary products. Came.

[0003]

However, although the conventional water-absorbent resin has a high water-absorbing ability with respect to water, its absorbing ability is significantly lowered in the presence of an electrolyte such as an inorganic salt. Proposals have been made to improve these. For example, a method of heating and insolubilizing a polysaccharide containing uronic acid or a salt thereof as a structural unit by crosslinking by heating (JP-A-56-5137), graft-polymerizing a water-soluble monomer and a crosslinking agent onto the polysaccharide. If necessary, further heat treatment (Japanese Patent Publication No. 3-68889, Japanese Patent Laid-Open No. 56-5138), and method of mixing an ion sealing agent with a water absorbent resin (Japanese Patent Laid-Open No. 56-89838).
No. gazette). However, in any case, since the improvement is not sufficient, the fact is that it has not been put to practical use.

[0004]

In view of the above problems, the present inventors have earnestly studied the present invention as a result of a study on a salt-absorbing absorbent composition having an excellent absorption performance for an aqueous salt solution. .

That is, the present invention comprises a water absorbent resin (A),
A sulfonic acid group-containing anionic surfactant (B), and 1 to 30 parts by weight of (B) per 100 parts by weight of (A).
The absorbent composition is 0 parts by weight.

In the present invention, the water-absorbent resin (A) is usually a hydrophilic cross-linking material having an absorption capacity of about 100 to 1000 times its own weight with respect to water and about 20 to 60 times with respect to physiological saline. Polymer, with carboxylic acid (salt) as its structural unit
The group [refers to a carboxylic acid and / or a carboxylic acid group.
The same description is used below. ], At least one of a sulfonic acid (salt) group, a phosphoric acid (salt) group, a tertiary amino group, a quaternary ammonium group, a hydroxyl group, a polyoxyethylene group, and the like.
The type and manufacturing method of the resin are not particularly limited as long as it is a water-absorbent resin having one hydrophilic group. Examples of this water-absorbent resin include starch-acrylic acid (salt) copolymers described in JP-B-53-46199 and JP-B-53-46200, JP-B-54-30710, JP-A-56- Crosslinked or self-crosslinked polyacrylic acid salt by the reverse phase suspension polymerization method described in 26909 publication, crosslinked polyacrylic acid (salt) obtained by aqueous solution polymerization described in JP-A-55-133413, etc., JPA
52-14689, Saponified copolymer of vinyl ester and unsaturated carboxylic acid or its derivative described in JP-A-52-27455, JP-A-58-2312, JP-A-61-36309 Sulfonic acid (salt) group-containing water-absorbent resin, isobutylene-maleic anhydride copolymer crosslinked product, starch-acrylonitrile copolymer hydrolyzate, crosslinked carboxymethyl derivative, crosslinked polyethylene oxide derivative, etc.
Examples thereof include crosslinked polyvinyl alcohol derivatives and polyacrylamide partially hydrolyzed products. Preferably, starch-acrylic acid (salt) having a carboxylic acid (salt) group,
Cross-linked polyacrylic acid (salt), saponified copolymer of vinyl ester and unsaturated carboxylic acid or its derivative, isobutylene-maleic anhydride copolymer cross-linked product, starch-
It is a hydrolyzate of an acrylonitrile copolymer, a crosslinked carboxymethyl derivative, or a partial hydrolyzate of polyacrylamide. Further, a water absorbent resin obtained by surface-crosslinking the above water absorbent resin can also be used. You may use together 2 or more types of said water absorbent resin.

The shape of the water-absorbent resin is not particularly limited as long as it is powdery, and it is granular, granular, granulated, flake shaped,
It may be in any shape such as a lump, pearl or fine powder. 90% by weight or more is a powdery granule having a particle size distribution of 1 mm or less, and particularly preferably 90% by weight or more.
It is a water-absorbent resin having a particle size distribution of 0.1 to 0.9 mm.

In the present invention, the surfactant (B) is an anionic surfactant having a sulfonic acid group. Preferred are alkane sulfonates and sulfonates containing a hydrophobic group containing an amide group or an ester group. More preferably, it is a sulfonate having a sulfoacetic acid ester group. A sulfonate having a carbon number of C _{12 to} C ₂₄ is suitable for the alkyl group. If the carbon number is less than 12,
If it exceeds 24, the effect is small. Examples of (B) include C ₁₂ , C ₁₄ , C ₁₆ , C ₁₈ , C ₂₀ , C ₂₂ and C ₂₄ sulfonates, C ₁₂ , C ₁₄ , C ₁₆ , C ₁₈ , C ₂₀ and C _22. , C ₂₄
Sulfonate ester salts of C ₁₂ , C ₁₄ , C ₁₆ , C ₁₈ , C
It is a sulfoacetic acid ester salt of ₂₀ , C ₂₂ and C ₂₄ . Further, two or more kinds of these surfactants may be used in combination.

The types of salts of the sulfoacetic acid salt of the surfactant (B) include alkali metal salts (sodium salt, potassium salt, lithium salt, etc.), ammonium salt, amine salt (triethanolamine salt, trimethylamine salt, etc.). )
And so on. Alkali metal salts are preferable, and sodium salts and potassium salts are more preferable.

The ratio of (A) to (B) is such that the amount of (B) is usually 1 to 300 parts by weight, preferably 5 to 150 parts by weight, relative to 100 parts by weight of (A). Even if the amount of (B) exceeds 300 parts by weight, the effect corresponding to the added amount cannot be obtained, which is uneconomical. On the other hand, if it is less than 1 part by weight, the effect of improving salt resistance cannot be obtained.

Conventionally, as a combination of a water-absorbent resin and a surfactant, for example, the water-absorbent resin is treated with a cationic surfactant having at least one C _{12 to} C ₂₄ alkyl group to improve Mamako and powder. There are proposals such as those with improved fluidity (Japanese Patent Laid-Open No. 61-69854), but since the salt resistance to salt is not mentioned, the salt resistance of the absorbent (improved absorption against salt solution is improved. ) Is essentially different from the present invention in which Further, the type of surfactant is also different from that of the surfactant (B) of the present invention.

As the method for producing the absorbent composition of the present invention, the method of mixing (A) with (B), the method of absorbing the aqueous solution of (B) in (A), and the step of producing (A) Method of adding (B) [eg (B) during polymerization of (A)
Or (B) is added to the polymer gel of (A)]. The preferred method is or.

As in the present invention, the reason why the water-absorbent resin and the anionic surfactant having a sulfonic acid group exhibit high absorption performance in an aqueous salt solution are not clear, but the network polymer chain of the water-absorbent resin is not clear. In particular, the polymer chain having a carboxylic acid group and the surfactant having a sulfonic acid group have some interaction with each other, and the surfactant has a function of preventing salts from penetrating into the network polymer of the water absorbent resin. However, as a result, it is considered that the salt solution exhibits high absorption performance similar to that of water.

In the absorbent composition of the present invention, a filler, water as an additive, organic powder (eg pulp powder, cellulose derivative, natural polysaccharides, etc.), inorganic powder (eg zeolite, ultrafine silica, alumina). , Bentonite, activated carbon, etc.), antioxidants, preservatives, bactericides, colorants, fragrances, other surfactants, etc. can be added as necessary, and these amounts are usually relative to the weight of the composition. It is 10% by weight or less.

[0015]

The present invention will be further described below with reference to Examples and Comparative Examples, but the present invention is not limited to these. The swollen gel volume ratio and the absorption amount (absorption capacity) of the absorbent composition were measured by the following methods. The amount added below is the amount added of the active ingredient.

Swelling gel volume ratio: test tube (φ = 14 mm; height 1
(6.5 cm), water-absorbent composition 0.1 g, deionized water 15 g
After swelling, a predetermined amount of salt (0.135 g of sodium chloride in the case of physiological saline) is added thereto and the swelling gel height (a) after standing for 1 hour is measured. On the other hand, 0.1 g of a water-absorbent resin to which no surfactant has been added is swollen with 15 g of deionized water, to which the same kind and the same amount of salt are added, and 1
The swollen gel height after standing for a period of time (b) is measured, and the swollen gel volume ratio is determined by the following formula. Swelling volume ratio (%) = (a / b) × 100 Absorption amount: The entire amount of the gel whose swollen gel volume ratio was measured is transferred to a 250 mesh nylon net tea bag and drained for 15 minutes to increase the weight (c). Is measured and the water absorption is calculated by the following formula. Absorption (g / g) = c × 10 Hereinafter, the present invention will be further described with reference to Examples and Comparative Examples, but the present invention is not limited thereto. The amount added below is the amount added of the active ingredient.

Example 1 0.1 g of cross-linked sodium acrylate-based water absorbent resin ("Sunwet IM-5000D" manufactured by Sanyo Kasei Co., Ltd.)
And 0.2 g of lauryl sulfoacetic acid ester salt (“LSA” manufactured by Nikko Chemicals Co., Ltd .; active ingredient 85%) were added and mixed to obtain an absorbent composition (a) of the present invention. Table 1 shows the results of measuring the swollen gel volume ratio and the amount of absorption of this absorbent composition in physiological saline. The absorbed amount of Sunwet IM-5000D with respect to physiological saline was 48 g / g.

Examples 2 and 3 Absorbent compositions (b) and (c) were obtained in the same manner as in Example 1 except that the addition amount of the surfactant "LSA" was changed as follows. It was The results of measuring the swollen gel volume ratio and the absorption amount are shown in Table 1. Absorbent composition (b): LSA added amount 0.1 g Absorbent composition (c): LSA added amount 0.01 g

Example 4 In the same manner as in Example 1 except that the amount of sodium chloride in measuring the swollen gel volume ratio in Example 1 was changed to 0.3 g, the swollen gel volume ratio and absorption amount in 2% saline solution were measured. The measured results are shown in Table 1. In addition, Sunwet IM-500
The amount absorbed by 0D of 2% saline was 39 g / g.

Example 5 The swollen gel volume ratio to 1% magnesium sulfate was the same as in Example 1 except that the seed and amount of the salt in measuring the swollen gel volume ratio in Example 1 were changed to 0.15 g of magnesium sulfate. Table 1 shows the results of measuring the absorption amount. The absorption amount of Sunwet IM-5000D with respect to 1% magnesium sulfate was 5 g / g.

Example 6 The same amount of "LSA" was added to the solid content of the polymer gel at the time of producing the crosslinked sodium acrylate-based water absorbent resin, and the mixture was dried to obtain an absorbent composition (d). Table 1 shows the results of measuring the swollen gel volume ratio and the absorption amount of this product in physiological saline.

Example 7 In Example 1, the crosslinked sodium acrylate-based water-absorbing resin was applied to "Sunwet IM-300" (manufactured by Sanyo Kasei Co., Ltd.), which is a crosslinked product of starch-acrylate graft copolymer. An absorbent composition (e) was obtained in the same manner as in Example 1 except that it was replaced. Table 1 shows the results of measuring the swollen gel volume ratio and the absorption amount of this product in physiological saline.
The absorption amount of Sunwet IM-300 with respect to physiological saline was 53 g / g.

Comparative Example 1 A comparative composition (f) was obtained in the same manner as in Example 1 except that the amount of the surfactant “LSA” added was changed to 0.0005 g. Table 1 shows the results of measuring the swollen gel volume ratio and the amount of absorption in these physiological saline solutions.

Comparative Example 2 A comparative composition (g) was obtained in the same manner as in Example 1 except that the surfactant "LSA" was changed to capryl sulfoacetate. Table 1 shows the results of measuring the swollen gel volume ratio and the amount of absorption in these physiological saline solutions.

[0025]

[Table 1]

[0026]

The salt-resistant water-absorbent resin of the present invention has the following features and effects. Excellent absorption performance for salt water. It exhibits excellent absorption performance for aqueous solutions of polyvalent ions. It can be manufactured by a simple operation.

Because of the above effects, the absorbent composition having excellent salt resistance of the present invention absorbs electrolyte-rich urine, blood, etc., such as disposable diapers, sanitary products, puerperium mats and medical underpads.・ Various sanitary materials used for gelation; Coagulants for water-containing substances that contain high concentrations of electrolytes such as industrial wastewater and seabed sludge; Sealing materials for civil engineering and shields that require high swelling power against seawater and hard water Applications such as mud-prevention agents for construction methods and waterproofing agents for submarine cables; applications such as curing materials after concrete placement and concrete admixtures;
It can be used for a wide range of industrial applications such as disposable body warmers and absorbents for high-concentration salt solutions such as desiccants containing calcium chloride as the main ingredient.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kenji Tanaka 1-11, Hitotsubashi Honmachi, Higashiyama-ku, Kyoto Sanyo Chemical Industry Co., Ltd.

Claims (7)

[Claims] 1. A water-absorbent resin (A) and an anionic surfactant (B) having a sulfonic acid group, wherein (A) 1
An absorbent composition in which (B) is 1 to 300 parts by weight with respect to 00 parts by weight. 2. The absorbent composition according to claim 1, wherein (B) is selected from any one of an alkane sulfonate and a sulfonate having a hydrophobic group containing an amide group or an ester group. 3. The absorbent composition according to claim 1, wherein (B) is an anionic surfactant having a sulfoacetic acid ester group. 4. The absorbent composition according to claim 1, wherein the alkyl group of (B) is C _{12 to} C ₂₄ . 5. (B) is 5 to 100 parts by weight of (A).
To 150 parts by weight, The absorbent composition according to any one of claims 1 to 4. 6. (A) is a starch-acrylic acid (salt) copolymer, a crosslinked polyacrylic acid (salt), a saponified product of a vinyl ester and an unsaturated carboxylic acid or a derivative thereof, isobutylene-maleic anhydride. At least one selected from the group consisting of a copolymer crosslinked product, a starch-acrylonitrile copolymer hydrolyzate, a crosslinked carboxymethylcellulose derivative, and a polyacrylamide partial hydrolyzate.
2. A water-absorbent resin containing different carboxylic acid groups.
The absorbent composition according to any one of 5 to 5. 7. The absorbent composition according to any one of claims 1 to 6, which has an absorption capacity for physiological saline of 60 to 150 times its own weight.