JPS60184540A - Composition containing powder of water-absorptive resin - Google Patents

Abstract

PURPOSE:The titled composition having a water-absorptive layer which is free of possibility of separation from its base when dried or swelled by absorbing wa ter, made by dispersing powders of a water-absorptive resin and of a water-soluble resin in a solution of a specified ethylenically unsaturated monocarboxylic acid copolymer. CONSTITUTION:40-100pts.wt. polyhydric alcohol ester of an ethylenically unsaturated monocarboxylic acid (e.g. hydroxyethyl acrylate), 0.1-10pts.wt. ethylenically unsaturated monocarboxylic acid (e.g. acrylic acid), and 0-50pts.wt. alkyl and/or vinyl ester of an ethylenically unsaturated monocarboxylic acid (e.g. methyl acrylate) are copolymerized to give a copolymer (A) having a molecular weight of at least 10,000. Then, 5-200pts.wt. powder of a water-absorptive resin (B) (e.g. a saponified, graft starch-acrylonitrile copolymer), and 0-20pts.wt. powder of a water-soluble resin (C) (e.g. PVA) are dispersed in a solution containing 20-100pts.wt. copolymer A to obtain the titled composition.

Description

Detailed Description of the Invention The present invention fj:i, 0 regarding the water-absorbing resin powder-containing composition. The present invention relates to a water-absorbing resin powder-containing composition that can be stably fixed on a body and at the same time form a water-absorbing layer in which the water-absorbing and swollen water-absorbing resin powder does not separate from the support.

Conventionally, water-absorbing resins, which can absorb and retain tens to hundreds of times their own weight of water within a few minutes, have generally been made with various polymer electrolytes or water-soluble resins that are physically or chemically moderated. Due to its composition and resin properties, it does not exhibit thermoplasticity, and it is difficult to make it into a film or fiber form by itself, so it is usually supplied in powder form.

Powdered water-absorbing resins are used in sanitary products such as sanitary napkins, disposable diapers, disposable cloths, water retention agents for agriculture and horticulture, oil-water separation agents, solid-liquid separation agents for sludge, water-absorbing processed materials such as ceilings and wall materials, etc. When applying water-absorbing resin powder to these applications, it is common to hold the powder on a continuous support. For example, (1) A method of making a water-absorbing sheet by embedding it into a water-permeable support such as paper or non-woven fabric using a mechanical method 0 (2) After spraying on the surface of the support such as paper or non-woven fabric, paper, A method of laminating nonwoven fabrics, etc.

(3) After mixing with hydrophilic fibers, the mixture is narrowed between two sheets of paper, non-woven fabric, etc.

(4) A method of finely dispersing in water or a low concentration emulsion liquid, then coating and drying on a support.

(5) A method of mixing with a hydrophilic or water-soluble resin and molding it into a sheet or other arbitrary shape.

(6) A method of dispersing polyester resin in ethyl acetate solution ("C" and then coating it on a polyester film (Japanese Patent Laid-open No. 5
(see Japanese Patent No. '7-103838) have been proposed or put into practical use.

However, in methods (1) to (3), the fixation of the water-absorbing resin powder to the support is insufficient, at the level of mere adhesion. It has the disadvantage that it easily separates and is not suitable for drying and reuse.

In method (4), the water-absorbing resin powder absorbs water and is applied in a swollen state, which has the disadvantage of requiring a large amount of energy for drying. The fixing power of the powder to the support is poor, and the above (1) to
It has the same drawback as (3) [7] Also, when the dispersion medium is an emulsion, partial destruction of the emulsion occurs when dispersing the water-absorbing resin powder in the emulsion solution, making it difficult to form a stable coated film. It has disadvantages such as being difficult.

In method (5), the water-absorbing resin powder is molded while being embedded in the moldable resin, so contact between the powder and water is restricted, and the amount of water absorbed commensurate with the amount of water-absorbing resin used is obtained. It has drawbacks such as not being able to be dried and its shape being destroyed during drying and reuse. In the method of Mari (6), when the water-absorbing resin powder has not yet absorbed water or moisture, it is well immobilized on the support, but when the powder is in a swollen state after absorbing water, it tends to separate from the support, making it difficult to reuse it. In addition to a decrease in water absorption capacity, polyester resins have disadvantages such as a decrease in water absorption and moisture absorption rate due to poor hydrophilicity.

As a result of repeated research to improve the above-mentioned drawbacks, the present inventors have found that if a composition consisting of a combination of a copolymer binder with a specific composition and a water-absorbing resin powder is used, the water-absorbing resin powder It does not separate from the support when it is dry or swollen after absorbing water, and it can easily form a water-absorbing layer that does not suffer from the disadvantages of a decrease in water-absorbing ability or water-absorbing rate even after repeated use of water absorption and drying. Thus, according to the present invention, 40 to 100 parts by weight of polyhydric alcohol ester of monoethylenically unsaturated carboxylic acid,
Copolymerization with 1 to 10 parts by weight of monoethylenically unsaturated carbon iRO and O to 50 M parts of alkyl ester and/or vinyl ester of monoethylenically unsaturated orocarboxylic acid 20 to 100! A water-absorbing resin powder-containing composition comprising 5 to 200 parts by weight of water-absorbing resin powder and 0 to 20 parts by weight of water-soluble resin powder dispersed in a copolymer solution containing i parts is provided. Ru.

The copolymer used in the composition of the present invention is a binder component for immobilizing the water-absorbing resin powder on a support,
Consists of polyhydric alcohol ester of monoethylenically unsaturated carboxylic acid and monoethylenically unsaturated carboxylic acid.

The polyhydric alcohol ester of monoethylenically unsaturated carboxylic acid in the copolymer contains hydroxyl groups and forms a hydrophilic polymer that itself has a water absorption capacity of about 30 to 50%. It is advantageously used as a binder for fixing the powder to a support without impairing properties such as water absorption capacity and water absorption rate. The amount of the polyhydric alcohol ester of monoethylenically unsaturated carboxylic acid blended is 40=100 parts by weight, preferably in the range of 50 to 95 parts by weight, and the blended amount is less than 40 parts by weight. The hydrophilicity or water permeability of the resulting copolymer binder decreases, and the water absorbency of the water absorbent resin powder decreases, while the blending amount is 100:! If the amount exceeds 1 part, a large amount of hydrophilic solvent such as alcohol is required to prepare the copolymer solution, which reduces the stability of the composition as a coating material, and also results in poor coating properties. This leads to drawbacks such as a lack of heat-sealability, which is required when forming a sheet and then laminating it to make a water-absorbing product.

Specific examples of polyhydric alcohol esters of monoethylenically unsaturated carboxylic acids that can be used in the copolymer include (4) hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, etc. These esters 1 can be used alone or in combination of two or more.

The other component constituting the copolymer, a monoethylenically unsaturated carboxylic acid, such as acrylic acid, methacrylic acid, etc., is used to disperse the water-absorbing resin powder and, if necessary, the water-soluble resin powder and to the support. As a component for stabilizing the adhesion, it can be used in an amount ranging from 0.1 to 10 parts by weight, preferably from 3 to 5 parts by weight. The blending amount is 0.
If it is less than 1 part by weight, the adhesion to a support such as glass or glass fiber non-woven fabric will be reduced, and if it is more than 10 parts by weight, the binder will become rigid and cranks will easily occur during bending of the coated sheet. Become.

The copolymer having the above composition may optionally contain alkyl esters and/or vinylesters of monoethylenically unsaturated carboxylic acids, such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, etc. ) acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate vinyl acetate,
Single polymers such as vinyl propionate can be copolymerized by combining two or more types, thereby improving film properties such as weather resistance, heat sealability, toughness, and bending workability of the resulting water absorption layer. can do. The copolymerization amount of these esters is 50 parts by weight or less, preferably 5 to 40 parts by weight.
Parts by weight are appropriate; if the amount of copolymerization exceeds 50 parts by weight, the water absorption capacity of the copolymer will be less than 30%, resulting in the disadvantage of slowing down the water absorption and quick ashing of the dispersed water-absorbing resin powder. So I don't like it.

It is not necessary to use any special method to prepare the copolymers used in the present invention; Alternatively, when polymerizing methacrylates, a known polymerization method can be used. For example, a known peroxide polymerization initiator or azo polymerization initiator may be added to the various esters.
l~.

It can be produced by adding 5% by weight and carrying out suspension polymerization or solution polymerization. In particular, with reference to the composition of the present invention,
Since the copolymer is used in the form of a solution, it is preferable to carry out the copolymerization by a solution polymerization method in which the esters are polymerized in an appropriate organic solvent. Organic solvents that can be used in solution polymerization include benzene, toluene, xylene, mineral spirit, petroleum benzine, cyclohexane, tetrahydrofuran, ethyl acetate, acetate ethylene glycol monoethyl ether acetate, acetone, methyl ethyl ketone, etc. The copolymer concentration in the organic solvent is preferably 20 to 50% by weight.

In addition, the copolymer not only immobilizes the water-absorbing resin powder on the support, but also improves the texture of the formed water-absorbing layer.
Since it is an important component that controls flexibility, processability, durability, etc., its molecular weight is 10,000 or more, especially 30,000 to 50,000.
00,000 is ideal, and its secondary transition point is 0 to 30°C.
In particular, the temperature is preferably 0 to 2'7°C. If the molecular weight of the copolymer is less than 10,000, defects such as shedding of dispersed particles during bending and covering of the film layer will occur, and if the secondary transition point is lower than 0°C, the image fabric surface will become sticky. 11. Pollution becomes stronger. On the other hand, if the temperature exceeds 30°C, the film layer will break due to bending and the texture will deteriorate.
Furthermore, it is preferable to use an appropriate plasticizer in combination with the copolymer, since this can increase the elongation of the copolymer binder, so that it can easily follow the water absorption swelling of the water-absorbing resin powder, and the It has the effect of preventing separation from the support. Plasticizers that can be used include phthalic acid, adipic acid and citric acid plasticizers, polyester plasticizers, and epoxy plasticizers, and the amount used is in the range of 0.5 to 10% by weight based on the copolymer. Good size.

In the present invention, there are no particular restrictions on the water-absorbing resin powder used in combination with the copolymer, and conventionally known ah powders can be used. For example, saponified starch-acrylonitrile graft polymer,
Graft copolymers of starch (or cellulose) and sodium acrylate, polymers crosslinked by heat treatment of partially saponified polyacrylic acid, copolymers of (meth)acrylic acid and crosslinking agent, Saponified products of self-crosslinking polymers that take advantage of their self-crosslinking properties, ionic bond complex polymers of polyacrylic acid with polyvalent metal ions, graft polymers of sodium polyacrylate that take advantage of the crystallinity of polyvinyl alcohol,
Powders such as polymers obtained by copolymerizing vinyl esters and (meth)acrylic esters and saponifying them with basic substances, and polymers obtained by saponifying copolymers of hydroxyethyl (meth)acrylates and acrylic esters. These are examples and are not intended to be limiting.

There is no particular limitation on the particle size of the water-absorbing resin powder, but the particle size in the final composition may be 7 μm or less, especially 3 lt m.
It is preferable that the particles be dispersed with the following particle size.If the particle size is larger than 7 μm, the unevenness of the coated and drying surface will become noticeable and the appearance will deteriorate, and the powder tends to easily separate after water absorption and swelling. .

Note that it is appropriate to disperse the water-absorbing resin powder into the copolymer solution using various known dispersing machines such as a roll mill or a ball-mino sand mill. Since it is carried out continuously, particle size 2
501. If the following water-absorbing resin powder is used as z++, a composition containing the water-absorbing resin powder pulverized and dispersed to a particle size of 7 μm or less can be easily prepared by the usual dispersion process using the above-mentioned known dispersing machine. can be obtained.

According to the present invention, the water-absorbing resin powder is blended in an amount of 5 to 200 parts by weight, preferably 25 to 150 parts by weight, based on 20 to 100 parts of the copolymer. can do.

If the amount of the powder is less than 5 parts by weight, the total amount of water absorbed per unit area will decrease, although it depends on the amount of application, and if it is more than 200 parts by weight, the swollen particles tend to separate easily, and when drying ( There is a tendency for the C coated surface (water absorption layer) to whiten.

According to the present invention, a composition composed of a copolymer solution and a water-absorbing resin powder as described above can form a water-absorbing layer having excellent water-absorbing properties.
If anything, it can be used suitably for applications that absorb relatively small amounts of moisture, such as applying it to the walls of buildings to absorb indoor moisture, but for applications that absorb large amounts of moisture, e.g. As an extreme example, when the water-absorbent resin is immersed in water to absorb water to the maximum water-absorbing capacity of the water-absorbent resin, when the water-absorbent resin powder is swollen by water absorption, the copolymer bindu is added to the water-absorbent resin. The powder may not be able to follow the pattern and the powder may separate from the support.

The above-mentioned drawbacks of the composition of the present invention can be improved by further incorporating a water-soluble resin powder into the composition. The water-soluble resin that can be used in the present invention is
For example, polyvinyl alcohol, polyethylene oxide,
Powders of polyethylene glycol, polyacrylamide, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, hydroxypropyl cellulose, sodium alginate, agar, gum arabic, etc. These (can be used alone or in combination of two or more types) Note that these powders are merely examples, and are not limited thereto.

The blending amount of water-soluble resin powder is 5 to 200 parts of water-absorbing resin powder.
It is preferably blended in an amount of 20 parts by weight or less, particularly in the range of 5 to 13 parts by weight, and can be varied depending on the intended use of the water-absorbing resin fixed to the support.

If the blending amount of the powder is more than 20 parts by weight, cracks may occur on the coated surface upon repeated use, and falling of the powder may be observed during drying. In addition, the particle size of this water-soluble resin is exactly the same as that of the water-absorbing raw resin powder described above. A composition containing the same can be easily obtained.

It is not necessarily clear why the immobilization of the water-absorbing resin powder on the support can be improved by blending the water-soluble resin powder into the composition consisting of the copolymer solution and the water-absorbing resin powder. No, but it is assumed to be approximately as follows.

In other words, a water-absorbing resin powder that has a water-absorbing capacity of 500 times its own weight can absorb, for example, a 1f sphere of 5009 g of water, and assuming that it absorbs water and swells, its surface area will reach more than 60 times, A binder made only of the copolymer cannot elongate to the extent that it can follow the volume change of the swollen particles, and interfacial peeling due to the difference in expansion coefficient between the water-absorbing resin powder and the binder causes the powder to separate from the support. It is expected that withdrawal will occur.

In particular, when the amount of water-absorbing resin powder used is the same as or more than that of the copolymer binder, and the amount of water absorbed per unit area is equal to that of the copolymer binder, detachment of the swollen powder is more likely to occur. However, when a water-soluble resin powder coexists there, the dissolution of the water-soluble resin powder and the water absorption (water absorption of the main resin powder) proceed simultaneously, but the dissolution rate of the water-soluble resin is compared to the water absorption rate of the water-absorbent resin. Because the water-soluble resin is dissolved slowly, it is absorbed by the water-absorbing resin before the water necessary for it to completely dissolve is provided, and as a result, the water-soluble resin powder becomes a highly viscous aqueous solution that is incompletely or partially dissolved. It is thought that particles are formed, and these high viscosity aqueous solution particles are mixed between the water-absorbing resin powders and act as a binder for the powders. Therefore, the composition of the present invention containing water-soluble resin powder has the binder effect of the water-soluble resin in addition to the binder effect of the copolymer, thereby doubling the effect of preventing the separation of the water-absorbing resin powder. it is conceivable that.

The composition of the present invention having the above-mentioned structure may further include various paint additives known in the field of paints, such as colorants, dispersion stabilizers, preservatives, antifungal agents, antioxidants, and ultraviolet absorbers. The agents can be formulated in conventional amounts. Next, this composition (is applied) by selecting an appropriate coating method from among coating methods known in the obstetric industry, such as spray coating, brush coating, roller coating, dip coating, roll coating, curtain flow coating, and electrostatic coating. Can be applied to the support,
It is preferable to adjust the viscosity to an appropriate level using an appropriate organic solvent to suit each coating method. The amount of the composition of the present invention to be applied is not particularly limited, and can be arbitrarily determined depending on the intended use of the resulting water-absorbing product.

The coated composition of the present invention can then be dried by any suitable known method such as air drying, hot air drying, hot air drying, infrared drying, heated roll drying, etc. to form a water-absorbing layer on the surface of the support.

Supports to which the composition of the present invention can be applied include organic or inorganic fiber cloth, nonwoven fabric, paper, wood, metal, plastic, cement products such as glass concrete, and composites of these materials.

As described above, the water-absorbing resin powder-containing composition of the present invention is composed of a composition suitable for coating, which contains a hydrophilic copolymer and, if necessary, a caloric water-soluble resin powder as a binder component. Therefore, it is easy to form a water-absorbing layer on the support, and the water-absorbing resin powder in the water-absorbing layer is stably fixed to the support without coming off even after repeated use due to repeated water absorption and drying. This makes it possible to provide water-absorbing products with extremely high practicality.

The present invention will be described in detail below with reference to Examples, but these Examples are merely examples and do not limit the present invention.

Example-l Hydroxypropyl methacrylate 1207, hydroxyethyl acrylate 807, acrylic acid 2P, 'r7
Propyl alcohol 207, toluene 20t, butyl selon 60g were placed in an rclooOyt flask equipped with a stirrer, a thermometer, and a condenser, and benzoyl peroxide 22 was added under stirring, and the polymerization reaction was maintained at 80°C for 10 hours. completed. (The nonvolatile content of the obtained copolymer solution was 49.6%, the molecular weight of the copolymer was l'l' 4000, and the second-order transition point was 92°C) This copolymer solution 200f! Water-absorbent resin powder (powder obtained by crushing Sumikage Nope water absorption capacity 450 times, manufactured by Sumitomo Chemical Co., Ltd. with a cyclojet mill manufactured by Seishin Enterprise Co., Ltd. and classifying it with a 200-mesh sieve) was added to it, and dispersed for 24 hours using a lt ball mill. The mixture was diluted with 40 g of isopropyl alcohol, 40 g of toluene, and butyl cellosolve 209, and taken out to prepare a composition containing water-absorbing resin powder.

The composition produced as described above is further prepared by (4c
After diluting toluene (approximately 302 g for 100 g of the composition) to a suitable viscosity for coating, the water-absorbing resin powder becomes 1 oz.
fk? The sample for testing was coated on a polyamide fiber nonwoven fabric (thickness: approximately 1 mm) at a ratio of The performance of the water-absorbing resin powder-containing composition was evaluated by conducting tests using the following tests and test methods on this sample. The evaluation results are shown in Table 1.

〔Test method〕

(1) Water absorption: Immerse the sample in water, measure the water absorption (g) when the water absorption reaches saturation, and calculate the water absorption (2) per 12 pieces of water-absorbing resin to determine the water absorption (a). .

(2) Retention rate of water-absorbing resin powder A sample of 10 x 10 cm was held on the water surface so that the water-absorbing layer was in contact with the water surface, and after being left for 48 hours, it remained on the support without being released into the water due to water absorption and swelling. The amount of water absorbed by the water-absorbing resin powder (7) is measured, and the water absorption amount (+
The water absorption amount (b) is calculated by converting it into i+), and the retention rate of the water-absorbing resin powder is determined by the following formula, that is, the percentage of the water absorption amount (a) according to the test method (1).

(3) Retention rate of water absorbent resin powder after repeated use (2) above
After the test is completed, the sample is once dried at room temperature, then absorbed again in the same manner as in test method (2) to measure the amount of water absorbed (7), and the amount of water absorbed (C) corresponding to the amount of water absorbed (b) is calculated. Therefore, the retention rate of the water absorbent resin powder after repeated use is calculated using the following formula.

(4) Moisture absorption rate A 1010×10 sample is left standing in an environment of 30° C. x 92% RH, and the change in weight due to water absorption at predetermined time intervals is measured as the water absorption amount (2) per water absorbent resin 17.

(5) Bending property: Bend the sample at a 90 degree angle around a 10 column φ so that the water absorption layer is on the outside, observe changes in the water absorption layer, and evaluate according to the following criteria.

○: Very good with no abnormalities such as cracks or falling of the water-absorbing resin powder @: Slight cracks are observed, but to the extent that they are not a practical problem Δ: The hardness of the water-absorbing layer has increased, and the texture is inferior. Example-2 The copolymer solution 2007 of Example 1 and the water-absorbing resin powder 100f of 20.0 mesh were added to Water-soluble resin powder (manufactured by Kuraray Co., Ltd.,
Add 15 g of bottle (PVA21+7) and take it out while diluting it with 1/= ball mill for 24 hours with 40 v1 of "Fl-rl inpropyl alcohol, 40 g of toluene, and 20 g of butyl cellosolve, and prepare a composition containing water-absorbing resin powder. Samples were prepared and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1. Example 3 Hydroxyethyl methacrylate) Ioog, butyl acrylate) 509, ethyl acrylate 507, acrylic acid 57, inpropyl alcohol thermometer, 1000, l with condenser attached
Put into a flask and press J<i> to add penzoyl oxide 22, and after dissolving, raise the internal temperature to 80°C and hold at 80°C for 1 hour to complete the polymerization reaction. (The non-volatile content of this polymer solution is 497%, the molecular weight of the copolymer is 152,000, and the second-order transition point is 13°C). and water-soluble resin powder 15f, and 1
After dispersion in a T-ball mill, the mixture was taken out while being diluted with xylene to prepare a water-absorbing resin powder-containing composition. (The particle size of the water-absorbing resin powder and the water-soluble resin powder in this composition was 3 μm or less.) A polyamide nonwoven fabric (thickness: 1 mm) similar to Example 1 was prepared as a support, and the above composition 1 was prepared. 0 0 ';/ (30 ft of toluene for C
' Added and translated, water absorbent resin powder is 109/n? It was coated so that
○Example-4 shown in )"oki7provir methacrylate) 120ii', 2
Ethylhexylacrine-) 2 B y, QMi hinyl 52f1 methacrylic acid 2fi+, ethyl acetate 100i
I', 60 g of isopropyl alcohol, and 4 fi' of azobisin butyronitrile were placed in the reactor used in Example 1 and maintained at 80° C. for 10 hours to complete the polymerization reaction.

The nonvolatile content of the obtained copolymer solution was 49.4%, the molecular weight of the copolymer was 150,000, and the second-order transition point was 21.2°C.

Thereafter, a water-absorbing resin powder-containing composition was produced in the same manner as in Example 1, and samples were prepared from this composition and then evaluated. The evaluation results were shown in Ken-1.

Example-5 Hydroxyethyl methacrylate loof.

Hydroxyethyl acrylate) 80 f, butyl acrylate 20 g, acrylic acid 47, inpropyl alcohol 1002, toluene 100 g benzoyl peroxide 6? A copolymerization reaction was carried out in the same manner as in Example 1. The nonvolatile content of this copolymer solution was 497%, and the molecular weight of the copolymer was 126,000. , the secondary transition point is 9,7
It was ℃.

A water-absorbing resin powder-containing composition was produced and evaluated in the same manner as in Example 1. The results are shown in Cloth-1.

Example-6 Water-absorbing resin powder (Sunwetsu manufactured by Sanyo Chemical Co., Ltd.) was added to 20Of of the copolymer solution of Example 5. -300 water absorption capacity 3
After adding 25 ft' of xylene and dispersing it in a sand mill (Super Mill manufactured by Bengami Seisakusho),
A water-absorbing resin powder-containing composition was prepared by taking out the mixture while diluting it at t.

Using the composition obtained above, in the same manner as in Example 1, water absorbency 1 roe powder was applied to a 75 μm thick polyethylene alephthalate film support at a ratio of 10f/n+F. A sample was prepared by drying in a hot air drying oven at 60° C. for 3 hours, and then evaluated. The evaluation results are shown in Table-1.

Example-7 Copolymer solution of Example 5 200? , water-absorbing resin powder (Sunwent M-300) 5ofi' and water-soluble resin powder (Alkox 1000 manufactured by Keiho Kagaku) 52
A water-absorbing resin powder-containing composition was produced in the same manner as in Example 6 using the same method as in Example 6, and evaluation samples were prepared and then evaluated. The evaluation results are shown in Table-1.

Example 8 Water absorbency was determined in the same manner as in Example 6 using the copolymer solution 2009 of Example 3, water absorbent resin powder (Sunwet IM-310) 140 y, and water soluble resin powder (Alcox 1000) 10 f. A resin powder-containing composition was produced, an evaluation sample was prepared, and then evaluated. The evaluation results are shown in Table-1.

Comparative Example-1 Using the reaction vessel of Example 1, methyl methacrylate 12
A copolymer solution was prepared using 0 g, butyl acrylate 1082, ethyl acrylate 722, toluene 3001, and benzo-t ruber oxide 32. The nonvolatile content of this copolymer solution was 49.6%, and the molecular weight of the copolymer was 15%.
The 3000° secondary transition point was 21°C.

The water absorbent resin powder 9Of used in Example 1 was added to the above copolymer solution 2001 and dispersed in the same manner as in Example 3 to produce a water absorbent resin powder-containing composition, which was then evaluated in the same manner as in Example 3. The evaluation results are shown in Table-1.

Comparative Example-2 Butyl methacrylate 20 using the reaction vessel of Example 1
0? A polymer solution was prepared using 200 g of Toirenin and 42 grams of Penn Soil Peroxide. The nonvolatile content of this solution was 492%, the molecular weight of the polymer was 130,000, and the second-order transition point was 23.6°C.

A composition was produced in the same manner as Comparative Example 1 using the above polymer solution and evaluated. The evaluation results are shown in Table-1.

Comparative Example-3 Using the reaction vessel of Example 1, butyl methacrylate,
609, vinyl acetate 1 o sy, butyl acrylate
) 32 f, ethyl acetate 120 f1 toluene 801
A copolymer solution was prepared using azobisisobutyronitrile 67. The nonvolatile content of this solution was 49.6%, the molecular weight of the copolymer was 114,000, and the second-order transition point was 8.2°C.

The same procedure as Comparative Example 1 was carried out except that this copolymer solution was used, and the evaluation results are shown in Table 1.

Comparative Example-4 The same procedure as Comparative Example 1 was carried out except that 152 ml of water-soluble resin powder (Poval PVA 21'7) was further added to the water-absorbing resin powder-containing composition of Comparative Example 1. The evaluation results of this product are shown in Table 1.

Comparative Example 5 Using the reaction vessel of Example 1, a copolymer solution was prepared from 60 g of hydroxyethyl methacrylate, 62 g of butyl acrylate, 782 g of butyl methacrylate, 200 g of toluene, and 4 g of benzoyl peroxinide. The nonvolatile content of this copolymer solution was 4,966%, the molecular weight of the copolymer was 114,000, and the second-order transition point was tri21°C.

A sample was prepared and evaluated in exactly the same manner as in Example 3, except that this resin solution 20Of was used. The evaluation results are shown in Table-1.

Below margin As is clear from the evaluation results in Table 1 above, Examples 1-
The composition of the present invention shown in No. 8 uses a copolymer containing a polyhydric alcohol ester of a monoethylenically unsaturated carboxylic acid and a monoethylenically unsaturated carboxylic acid as essential components as a binder for the water-absorbing resin powder. Therefore, it is important to provide a water-absorbent product that stably holds (immobilizes) the water-absorbing resin powder on a support without impairing its water-absorbing properties such as its water-absorbing capacity (water absorption amount) and water-absorbing speed. It's an excellent thing to do.

In particular, the groups shown in Examples 2 to 5.7.8 containing water-soluble resin powder, which is an embodiment of the present invention, are
(3) As shown in the retention rate evaluation results, almost no separation of the water-absorbing resin powder is observed even after repeated use by repeatedly absorbing water, drying, and absorbing water. It was an extremely excellent product that could provide a water-absorbing product.

On the other hand, the compositions of Comparative Examples 1 to 4 using a binder having a composition ratio that does not belong to the present invention have a smaller water absorption 1k and a slower water absorption rate than the compositions of the present invention, and the water absorbent resin powder A decrease in retention rate (decrease in water absorption ability) due to detachment from the support was observed, making it impractical.

Furthermore, excluding one of the essential components of the copolymer of the present invention,
The composition of Comparative Example 5, which does not belong to the present invention and uses a copolymer using only a polyhydric alcohol ester of a monoethylenically unsaturated carboxylic acid as a binder, has a high water absorption rate because the copolymer binder is hydrophilic. Although the i was large, the water absorption rate was somewhat slow, and detachment of the water-absorbing resin powder was observed, indicating that the composition needed improvement.

Patent applicant: Fujikura Kasei Co., Ltd.

Claims (1)

[Claims] 40 to 100 parts by weight of polyhydric alcohol ester of monoethylenically unsaturated carboxylic acid, 0 to 10 parts by weight of monoethylenically unsaturated carboxylic acid, and 0 to 10 parts by weight of alkyl ester and/or vinyl ester of monoethylenically unsaturated carboxylic acid. 50 parts by weight of a copolymer and 5 to 20 parts by weight of a water-absorbing resin powder and O to 20 parts by weight of a water-soluble resin powder are dispersed in a copolymer solution containing 20 to 100 parts by weight of a copolymer. A composition containing water-absorbing resin powder.