JPH05320270A - Production of water-absorptive polymer - Google Patents

Abstract

PURPOSE:To produce a water-absorptive polymer which is excellent in light resistance and durability, has high gel strength and high water absorbency, gives the ground high air permeability scattered into the ground, and is suitable, e.g. for agriculture and horticulture and for afforestation of a desert. CONSTITUTION:An ethylenically unsaturated amine and/or its salt is polymerized on the surface and/or in the inside of a water-absorptive resin comprising a polyacrylic acid to produce a water-absorptive polymer having a surface covered with the ethylenically unsaturated amine and/or its salt and/or having an interpenetrated polymer network structure.

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The present invention is highly stable to sunlight, has a high water absorption capacity, a high water absorption rate, a high gel strength, and a water absorption property capable of sufficiently maintaining the air permeability in the ground when sprayed in the ground. It relates to a method for producing a polymer. The water-absorbent polymer obtained in the present invention absorbs several tens of times its own weight or more of water, has high stability to light such as sunlight, and does not deteriorate various performances even against underground salts, and also gel. Due to its high strength, it can be used as a water retention agent for agriculture and horticulture, a greening material for deserts, a lubricant for excavation for civil engineering construction, a water-absorption solidifying agent for muddy water, a water-stopping agent, a humidity control wallpaper for construction, and vegetables, fruits, etc. It is used for water retention and humidity control to maintain freshness.

[0002]

2. Description of the Related Art Starch graft polymer as a water absorbent resin,
Crosslinked products of polyacrylic acid salts are known. However, when the conventional water-absorbent resin is used for agricultural and horticultural purposes and desert greening, the light resistance to sunlight is weak and various performances are deteriorated in the presence of salt in the ground. In particular, the conventional water-absorbent resin for disposable diapers absorbs 1 when exposed to sunlight.
It decomposes within a day. In addition, when sprayed in the ground, the strength of the absorbed gel is weak and the gel collapses due to pressure, which causes poor air permeability in the ground and causes root rot. Conventional water-absorbent resins usually have the above-mentioned drawbacks.

[0003]

When the water-absorbent resin is used for agricultural and horticultural purposes and desert greening, it must have light resistance to sunlight, various performances against salt in the ground, and further When it is sprayed on the ground, it is required that the air permeability in the ground is excellent, etc., but it is necessary to satisfy all of these, and further, it must be a lubricant for excavation for civil engineering and construction, a water-absorbing solidifying agent for muddy water, a water-stopping agent, and a moisture absorbent for construction. When it is used as wallpaper, it is required to have water absorption ability, high gel strength, light resistance and the like.

[0004]

In order to solve the above-mentioned problems, the present inventors have investigated water-absorbing polymers having various structures, and have found that the water-absorbing polymers are produced by the specific method of the present invention. As a result, they have found that the above problems can be solved, and completed the present invention.

That is, according to the present invention, the surface and / or the inside of the ethylenically unsaturated carboxylic acid polymer-based water absorbent resin is
Water absorption characterized by polymerizing ethylenically unsaturated amine and / or its salt, whose surface is coated with a polymer of ethylenically unsaturated amine and / or its salt and / or which has an interpenetrating polymer network structure The present invention relates to a method for producing a hydrophilic polymer.

As the ethylenically unsaturated carboxylic acid polymer-based water-absorbing resin used in the present invention, various known water-absorbing resins such as polyacrylic acid-based water-absorbing resin can be used and are not particularly limited. For example, those obtained by polymerizing an ethylenically unsaturated carboxylic acid and / or salt thereof, a polymerizable cross-linking agent, and optionally other polymerizable monomer, and further (partially) neutralizing, or an ethylenically unsaturated Examples thereof include a polymer of a carboxylic acid and / or a salt thereof or an ethylenically unsaturated carboxylic acid and / or a salt thereof and another polymerizable monomer, which has a crosslinked structure using a crosslinking agent.

Examples of the ethylenically unsaturated carboxylic acid and / or its salt include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid and fumaric acid and / or their alkali metal salts such as Na, K and Li. , Ammonium salts, amine salts and the like.

Other polymerizable monomers include various monomers copolymerizable with the ethylenically unsaturated carboxylic acid and / or its salt, and are not particularly limited. For example, (meth) acrylamide, N-methylol (meth). Acrylamide, hydroxyethyl (meth) acrylate, N-
Vinylpyrrolidone, methyl vinyl ether, (or water-soluble vinyl monomers such as vinyl monomers having a sulfonic acid group such as acrylamidomethylpropanesulfonic acid, allylsulfonic acid, styrenesulfonic acid and its alkali metal salts, ammonium salts, amine salts, etc., Examples thereof include esters such as (meth) acrylic acid having an alkyl group having 1 to 18 carbon atoms, and water-insoluble vinyl monomers such as (meth) acrylonitrile and vinyl acetate.

The amount of the water-soluble vinyl monomer used is preferably 0 to 50% by weight of the ethylenically unsaturated carboxylic acid and / or its salt, and the amount of the water-insoluble vinyl monomer used is the ethylenically unsaturated carboxylic acid. It is preferably 0 to 20% by weight of the carboxylic acid and / or its salt.

Examples of the polymerizable cross-linking agent include various known polyfunctional monomers, such as divinylbenzene,
Methylenebis (meth) acrylamide, ethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, glycerin tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, pentaerythritol tetra Examples thereof include (meth) acrylate and pentaerythritol tetraethylene oxide tetra (meth) acrylate.

In addition to the above-mentioned polymerizable cross-linking agents, various cross-linking agents can be used. For example, polyglycidyl ethers such as ethylene glycol diglycidyl ether and polyethylene glycol diglycidyl ether, epichlorohydrin, epibromhydrin, α- Haloepoxy compounds such as methyl epichlorohydrin, glycidol, ethylene glycol monoglycidyl ether, propylene glycol monoglycidyl ether, monoepoxy alcohols such as glycerin monoglycidyl ether, glutaraldehyde, polyaldehyde compounds such as glyoxal,
Ethylene glycol, glycerin, triethanolamine, pentaerythritol, polyethylene glycol,
Polyol such as polyvinyl alcohol, Ca, Mg, A
An inorganic salt or an organic salt which produces a polyvalent metal ion such as 1 can be mentioned.

These various cross-linking agents other than the above-mentioned polymerizable cross-linking agents are used for producing an ethylenically unsaturated carboxylic acid polymer water-absorbing resin by polymerization of raw material monomers, before polymerization, during polymerization, or after polymerization. It may be added at any time. The use ratio of the polymerizable crosslinking agent and various crosslinking agents,
It is preferably 0.01 to 10% by weight based on the total amount of the ethylenically unsaturated carboxylic acid and / or its salt and other polymerizable monomers.

The ethylenically unsaturated carboxylic acid polymer-based water absorbent resin used in the present invention can be used in various shapes such as powder, particles, blocks and sheets, and is not particularly limited.

In the present invention, the ethylenically unsaturated amine and / or its salt is polymerized on the surface and / or inside of the ethylenically unsaturated carboxylic acid polymer water absorbent resin.

Examples of the ethylenically unsaturated amine and / or salt thereof include vinyl monomers having an amino group or a quaternary ammonium salt group, such as dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate and dimethylamino. Propyl (meth) acrylamide, diethylaminopropyl (meth) acrylamide, dimethylaminomethyl (meth) acrylamide, 2-vinylpyridine, 4-vinylpyridine, allylamine, dimethylallylamine, diallylmethylamine, (meth) acryloyloxyethyltrimethylammonium chloride or Bromide or sulphate, (meth) acryloyloxypropyltrimethylammonium chloride or bromide or sulphate, (meth) actuate Acryloyloxy-hydroxyethyl trimethyl ammonium chloride or bromide, or sulfate, a reaction product of dimethylaminopropyl (meth) acrylamide and alkyl halide or dialkyl sulfate, unsaturated amine and the like, quaternary ammonium salts.

When the ethylenically unsaturated amine and / or its salt is polymerized, other polymerizable monomers can be used together. Examples of other polymerizable monomers that can be used in combination include the above-mentioned ethylenically unsaturated carboxylic acids and / or salts thereof, the above-mentioned other polymerizable monomers (water-soluble vinyl monomer, water-insoluble vinyl monomer) and the like. The proportion of the other polymerizable monomer that can be used in combination is preferably 0 to 100% by weight, and particularly preferably 0 to 50% by weight based on the ethylenically unsaturated amine and / or its salt.

When polymerizing the ethylenically unsaturated amine and / or its salt, a crosslinking agent is used. As a cross-linking agent,
The above-mentioned polymerizable cross-linking agent and the above-mentioned various other cross-linking agents and the like can be mentioned. The amount of these cross-linking agents used is preferably 0.01 to 10% by weight, particularly 0.1 to 5% by weight, based on the total amount of the ethylenically unsaturated amine and / or its salt and other polymerizable monomers. % Is preferable.

An aqueous solution or a hydrophilic or hydrophobic organic solvent solution containing an ethylenically unsaturated amine and / or a salt thereof, a cross-linking agent, a polymerization initiator and, if necessary, another polymerizable monomer is added to an ethylenically unsaturated carboxylic acid polymer system. Polymerize in addition to the water absorbent resin.

As the polymerization initiator, known polymerization initiators can be used, for example, ammonium persulfate, potassium persulfate, hydrogen peroxide, t-butyl hydroperoxide, 2,2'-azobis (amidinopropane). ) Hydrochloride and the like. The amount of the polymerization initiator used is 0.01 to 10% by weight based on the total amount of monomers contained in the solution added to the ethylenically unsaturated carboxylic acid polymer-based water absorbent resin.
Is preferred.

The hydrophilic or hydrophobic organic solvent is not particularly limited, and any solvent can be used as long as it dissolves the monomer and the polymerization initiator used. For example, acetone, methanol, ethanol, isopropanol, tetrahydrofuran, dioxane. , Hexane, toluene, ethyl acetate and the like.

Monomers (ethylenically unsaturated amine and / or salt thereof + crosslinking agent +) in an aqueous solution or an organic solvent solution
The concentration of the other polymerizable monomer) is not particularly limited, but is usually preferably about 5 to 80% by weight.

The ratio of the aqueous solution or the organic solvent solution to the ethylenically unsaturated carboxylic acid polymer-based water absorbent resin is not particularly limited, but the ethylenically unsaturated amine and //
Alternatively, the amount of the salt thereof is preferably 1 to 200% by weight, particularly preferably 5 to 50% by weight.
Weighting is preferably carried out at temperatures between 0 and 100 ° C.

The polymer obtained by polymerizing as described above may be pulverized after polymerization, if necessary, dried by a hot air dryer, a reduced pressure dryer, etc., and optionally pulverized and granulated for use. .. Further, like the conventional water-absorbing agent, the surface of the particles may be further crosslinked to improve the water-absorbing speed and strengthen the gel strength.

In the present invention, whether the polymerization of the ethylenically unsaturated amine and / or its salt is carried out on the surface and / or inside the water-absorbent resin depends on the amount of the aqueous solution or organic solvent solution used or the organic solvent. It can be freely controlled by appropriately selecting the kind of the solvent. Therefore, by appropriately selecting these, the surface is coated with a polymer of an ethylenically unsaturated amine and / or a salt thereof and / or an interpenetrating polymer. A water absorbing polymer having an arbitrary structure having a network structure can be freely obtained.

By using the method of the present invention, the stability to sunlight is high, the water absorption capacity is high, the water absorption speed is high,
It is possible to obtain a water absorbent polymer having a high gel strength. Furthermore, even if the water-absorbent polymer obtained in the present invention is sprinkled in the ground, the air permeability in the ground is sufficiently maintained. Therefore, the water-absorbent polymer obtained in the present invention is a water-retaining material for agriculture and horticulture, a greening material for deserts, a lubricant for excavation for civil engineering, a water-absorption solidifying agent for muddy water, a water-stopping agent, a moisture absorbent wallpaper for construction, and It can also be used as a moisture retaining agent for keeping the freshness of vegetables and fruits, and as a humidity control agent.

[0026]

The present invention will be described in more detail with reference to the following examples. In addition, the part in an Example shows a weight part.

Example 1 Sodium hydroxide (43 parts) was dissolved in water (130 parts), and acrylic acid (100 parts) was added to the resulting aqueous solution to add ammonium persulfate (0.16 parts) and methylenebisacrylamide (0.2 parts). Nitrogen gas was blown into the mixture with stirring to expel dissolved oxygen to prepare a monomer aqueous solution. To this, 0.03 part of L-ascorbic acid was added and static polymerization was carried out at 30 to 100 ° C to obtain a gel-like hydropolymer. The gel-like water-containing polymer was roughly crushed, dried with a hot air dryer at 170 ° C., pulverized, and sieved with an 18-mesh wire net to obtain an 18-mesh pass product.

To 40 parts of this powder, an aqueous solution containing 18 parts of dimethylaminoethyl methacrylate, 20 parts of water, 0.08 part of ammonium persulfate and 0.1 part of methylenebisacrylamide was added and stirred, and nitrogen gas was blown thereinto to blow oxygen. Was removed to prepare a monomer-coated water-absorbent resin. Add L-ascorbic acid 0.01 parts and water 5 parts to this
Polymerization was carried out at 0 to 100 ° C to obtain a granular water-containing polymer. Further colloidal silica (Nissan Chemical Snowtex O 20%
A mixture of 2 parts of an aqueous solution) and 4 parts of methanol is added and dispersed. To this, a solution of 0.24 parts of glycidol in 2.4 parts of water is added and stirred. The obtained mixture is heated to 180 ° C.
Was dried by heating with a hot air dryer for 30 minutes to obtain a water-absorbing polymer having a coating structure.

Example 2 15 parts of acryloyloxyethyl trimethyl ammonium chloride in place of dimethylaminoethyl methacrylate, 0.4 parts of polyethylene glycol 400 diacrylate in place of methylene bisacrylamide, 1.0 part of hydrogen peroxide in place of ammonium persulfate. A water absorbing polymer having a coating structure was obtained by the same method as in Example 1 except that was used.

Example 3 18 parts of dimethylaminoethyl acrylate instead of dimethylaminoethyl methacrylate, 0.4 parts of polyethylene glycol 200 diacrylate instead of methylenebisacrylamide, and 1 part of acetone instead of 20 parts of water.
A water-absorbent polymer having a coating structure was obtained in the same manner as in Example 1 by using 0 part and 10 parts of water.

Example 4 43 parts of sodium hydroxide was dissolved in 130 parts of water, and 100 parts of acrylic acid was added to the solution to prepare an aqueous solution.
% Hydrogen peroxide (1.0 part) was added, and the mixture was stirred and nitrogen gas was blown thereinto to expel dissolved oxygen to prepare a monomer aqueous solution.
L-ascorbic acid (0.03 parts) was added to this, and 30 to 1
The mixture was allowed to stand at 00 ° C for polymerization to obtain a gel-like hydropolymer. The gelled hydropolymer was crushed to obtain a lump resin.

To 100 parts of this resin, 100 parts of a 10% aqueous solution of dimethylaminoethyl methacrylate, 0.04 part of polyethylene glycol 400 diacrylate and 0.02 part of ammonium persulfate were absorbed,
After blowing nitrogen gas, 0.01 part of L-ascorbic acid and 10 parts of water were added thereto, and the mixture was polymerized at 30 to 100 ° C., dried with a hot air dryer at 170 ° C., pulverized, and wire mesh of 18 mesh was used. It was sieved to obtain an 18-mesh passed product.

To 40 parts of this powder, a mixture of 0.3 part of silica fine powder (Aerosil 130 manufactured by Nippon Aerosil) and 10 parts of methanol was added and dispersed, and 0.2 part of glycidol was dissolved in 2 parts of water. Add the solution and stir. The resulting mixture was heated and dried with a hot air dryer at 160 ° C. for 40 minutes to obtain a water absorbing polymer having an interpenetrating polymer network structure.

Example 5 34 parts of sodium hydroxide was dissolved in 130 parts of water, 80 parts of acrylic acid and 20 parts of acrylamidomethylpropanesulfonic acid were added thereto, and ammonium persulfate 0.16 was added.
And 0.2 part of methylenebisacrylamide were added and stirred, and nitrogen gas was blown thereinto to expel dissolved oxygen to prepare a monomer aqueous solution. L-ascorbic acid 0.0
3 parts was added and the mixture was allowed to stand and polymerize at 30 to 100 ° C. to obtain a gel-like hydropolymer.

After the gel-like water-containing polymer was roughly crushed, 70 parts of a 30% aqueous solution of dimethylaminoethyl acrylate, to which 0.16 parts of ammonium persulfate and 0.2 parts of methylenebisacrylamide were added, were absorbed. The mixture was allowed to stand and polymerized at 50 to 100 ° C. to obtain a lumpy hydropolymer. This lumpy hydropolymer was dried with a hot air dryer at 170 ° C., pulverized and sieved with an 18 mesh wire net to obtain an 18 mesh passed product.

To 40 parts of this powder, a mixture of 2 parts of colloidal silica (20% aqueous solution of Snowtex O manufactured by Nissan Chemical Industry Co., Ltd.) and 4 parts of methanol was added and dispersed, and 0.2 part of glycidol was added to 2 parts of water. Add the solution dissolved in and stir. The obtained mixture is dried in a hot air dryer at 180 ° C. for 30 minutes.
After heat-drying for a minute, a water-absorbing polymer having an interpenetrating polymer network structure was obtained.

COMPARATIVE EXAMPLE 1 43 parts of sodium hydroxide was dissolved in 130 parts of water, and 100 parts of acrylic acid was added to the resulting solution to prepare 0.2 parts of methylenebisacrylamide and 0.1 parts of ammonium persulfate.
Six parts were added and stirred, and nitrogen gas was blown thereinto to expel dissolved oxygen. To this, 0.03 part of L-ascorbic acid was added and static polymerization was carried out at 30 to 100 ° C to obtain a gel-like hydropolymer. The gel-like water-containing polymer was roughly crushed, dried with a hot air dryer at 170 ° C., pulverized, and sieved with an 18-mesh wire net to obtain an 18-mesh pass product. For 40 parts of this powder, colloidal silica (Snowtex O manufactured by Nissan Chemical Co., Ltd.
A mixture of 2 parts of a 20% aqueous solution) and 4 parts of methanol is added and dispersed. To this, a solution of 0.24 parts of glycidol in 2.4 parts of water is added and stirred. The resulting mixture is 1
A water absorbent resin was obtained by heating and drying for 30 minutes with a hot air dryer at 80 ° C.

Comparative Example 2 The same procedure as in Comparative Example 1 was repeated except that 0.4 part of polyethylene glycol 400 diacrylate was used instead of methylenebisacrylic amide and 1.0 part of 35% hydrogen peroxide was used instead of ammonium persulfate. Polymerization, drying and pulverization were carried out to obtain a powder. To 40 parts of this powder, a mixture of 0.3 part of silica fine powder (Aerosil 130 manufactured by Nippon Aerosil Co., Ltd.) and 10 parts of methanol was added and dispersed, and a solution prepared by dissolving 0.2 part of glycidol in 2 parts of water was added thereto. Add and stir. The resulting mixture was heated and dried with a hot air dryer at 160 ° C. for 40 minutes to obtain a water absorbent resin.

COMPARATIVE EXAMPLE 3 Instead of 100 parts of acrylic acid, 80 parts of acrylic acid and 20 parts of acrylamidomethylpropanesulfonic acid were used.
Polymerization was performed in the same manner as in Comparative Example 1 except that 34 parts of sodium hydroxide was used instead of 43 parts, and the mixture was dried and pulverized to obtain a powder. To 40 parts of this powder, a mixture of 2 parts of colloidal silica (Snowtex O 20% aqueous solution manufactured by Nissan Chemical Industry Co., Ltd.) and 4 parts of methanol was added and dispersed, and 0.2 parts of glycidol was dissolved in 2 parts of water to prepare a solution. Add and stir. The obtained mixture was heated with a hot air dryer at 180 ° C. for 30 minutes to obtain a water absorbent resin.

Application Example 1 Water-absorbing polymers obtained in Examples 1-5 and Comparative Example 1
Table 1 shows the initial water absorption capacity, the water absorption capacity at each sun exposure time, and the gel strength of the water absorbent resins obtained in Examples 1 to 3.

Table 1 Water-absorbent polymer initial water absorption capacity Water absorption capacity after sunlight exposure time Gel strength or water-absorbent resin (g / g polymer) (g / g polymer) (g / cm ² ) 24hrs 48hrs 72hrs Example 1 50 39 42 33 910 Example 2 90 50 50 53 36 830 Example 3 35 44 45 51 10 15 Example 4 80 86 90 90 64 800 Example 5 68 89 93 47 760 Comparative Example 1 73 4 0 0 176 Comparative Example 2 102 2 0 0 246 Comparative Example 3 95 20 2 0 420

In Application Example 1, the water absorption capacity, the water absorption capacity after exposure to sunlight, and the gel strength were measured as follows. ○ Water absorption ratio 200g of tap water was added to 0.5g of water-absorbent polymer powder,
After 1 hour, the weight of the resin absorbed by filtration through a 200-mesh wire net is weighed, and this is divided by the weight of the powder to obtain the water absorption ratio.

○ Water absorption capacity after exposure to sunlight 200 g of tap water was added to 0.5 g of the water-absorbent polymer powder, and after exposure to sunlight for a predetermined time, it was filtered through a 200-mesh wire net and the weight of the absorbed resin was weighed. This is divided by the weight of the powder to obtain the water absorption capacity.

Gel strength: 2 g of water-absorbent polymer powder was weighed in a beaker of 200 ml, added with 2 g of methanol and immersed therein, and then 40 g
Add pure water of at once and stir to form a water-absorbing gel. After that, a cylindrical adapter having a diameter of 6 cm is placed on the water-absorbing gel in the beaker and compressed with Tensilon to measure the strength at which the gel starts to flow. The gel strength is represented by the stress per unit area of the cylinder.

As is clear from Table 1, according to the present invention, strong characteristics against sunlight and salt, water absorption capacity after exposure to sunlight, and gel strength are exhibited, which is excellent for agricultural and horticultural and desert greening. A water absorbent polymer can be obtained.

[0046]

EFFECTS OF THE INVENTION According to the present invention, a water-absorbing polymer having excellent light resistance and durability, excellent water absorption capacity, water absorption speed, gel strength, and capable of sufficiently maintaining air permeability in the ground when sprayed in the ground is obtained. be able to.

Claims (1)

[Claims] 1. An ethylenically unsaturated amine having a surface, characterized in that an ethylenically unsaturated amine and / or a salt thereof is polymerized on the surface and / or inside of an ethylenically unsaturated carboxylic acid polymer water absorbent resin. And / or a polymer of a salt thereof and / or a method for producing a water-absorbing polymer having an interpenetrating polymer network structure.