JP2967952B2 - Method for producing porous polymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to
The present invention relates to a method for producing a porous polymer which is rich in absorbency of water and alcohol, and has high gas permeability, high absorption rate, and high gel strength. The water-absorbing polymer absorbs water several hundred times its own weight and has a high absorption capacity for urine, blood and alcohol, so it is used for sanitary napkins, disposable diapers, medical cataplasms, disinfecting cotton, wound treatment Used for accompanying plasters. In addition, because of its high gel strength, water retention agents for agricultural and horticultural use, drilling lubricants for civil engineering construction, water absorbing agents, water stopping agents, moisture absorbing wallpapers for construction, and water retention and humidity control for maintaining the freshness of vegetables, fruits, etc. Used in medicine.

[0002]

2. Description of the Related Art Various types of water-absorbing polymers are known, and powdery, granular, spherical and fibrous ones are generally known.

[0003]

However, when a water-absorbing polymer is used for disposable diapers, sanitary napkins and the like, it is mixed with flocculent pulp, so that it has a low apparent specific gravity, blood, urine, etc. It is required that the gel be rapidly absorbed and the elasticity of the gel after the absorption be further improved, and none of them satisfy these requirements.

Further, when used as a poultice for medical use, a poultice, a disinfecting cotton, etc., water absorbing ability, alcohol absorbing ability, high gel strength, and the like are required. They did not always fully meet these requirements.

[0005]

SUMMARY OF THE INVENTION The present invention has been found to solve the above-mentioned problems by producing a porous polymer having pores therein by a specific method, and has completed the present invention.

That is, in the present invention, in producing a porous polymer, a surfactant or a polymer dispersant is used, the dispersed phase is a hydrophobic phase, and the continuous phase contains at least one water-soluble polymerizable monomer. The present invention relates to a method for producing a porous aqueous polymer, which comprises forming an O / W emulsion as an aqueous phase, polymerizing and drying the O / W emulsion.

The water-soluble polymerizable monomer used in the present invention includes vinyl monomers having a polymerizable unsaturated group such as ethylenically unsaturated carboxylic acid, ethylenically unsaturated sulfonic acid, ethylenically unsaturated amine and salts thereof. Is mentioned. Among them, examples of the ethylenically unsaturated carboxylic acids and salts thereof include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, and fumaric acid, and alkali metal salts such as Na, K, and Li, and ammonium salts thereof. And amine salts.

Examples of the ethylenically unsaturated sulfonic acids and salts thereof include acrylamidomethylpropanesulfonic acid, allylsulfonic acid, styrenesulfonic acid and alkali metal salts, ammonium salts and amine salts thereof. Examples of the ethylenically unsaturated amine and its salt include unsaturated amines such as dimethylaminoethyl (meth) acrylate, (meth) acryloyloxyethyltrimethylammonium chloride, allylamine, and quaternary ammonium salts.

In the present invention, another monomer copolymerizable with the water-soluble polymerizable monomer can be used in combination with the water-soluble polymerizable monomer. Other monomers include, for example, (meth) acrylamide, N-methylol (meth) acrylamide, hydroxyethyl (meth) acrylate, N-vinylpyrrolidone, methyl vinyl ether
Examples thereof include water-soluble monomers such as tellurium, alkyl esters having 1 to 18 carbon atoms such as (meth) acrylic acid, and water-insoluble vinyl monomers such as (meth) acrylonitrile and vinyl acetate. , 0 of all monomers
The proportion is preferably such that it occupies ５０50% by weight.

A cross-linking agent can be used in order to obtain an absorbent porous polymer that absorbs water, alcohol, and the like, and various known cross-linking agents can be used.
For example, those added before polymerization include divinylbenzene, methylenebis (meth) acrylamide, ethylene glycol (meth) acrylate, polyethylene glycol (meth) acrylate, trimethylolpropane tri (meth) acrylate, glycerin tri (meth) acrylate, Examples thereof include pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, and pentaerythritol tetraethylene oxide tetra (meth) acrylate.

Examples of the crosslinking agent which may be added before, during or after the polymerization include, for example, polyglycidyl ethers such as ethylene glycol diglycidyl ether and polyethylene glycol diglycidyl ether, epichlorohydrin, epibromo and the like. Examples include haloepoxy compounds such as hydrin and α-methylepichlorohydrin, and monoepoxy alcohols such as glycidol, ethylene glycol monoglycidyl ether, propylene glycol monoglycidyl ether, and glycerin monoglycidyl ether.

Further, polyaldehyde compounds such as glutaraldehyde and glyoxal; polyols such as ethylene glycol, glycerin, triethanolamine, pentaerythritol, polyethylene glycol and polyvinyl alcohol; polyamines such as ethylenediamine, hexamethylenetetramine and monoethanolamine;
An inorganic salt that produces polyvalent metal ions such as Ca, Mg, and Al;
Alternatively, an organic salt or the like can be used as a crosslinking agent.

In the present invention, the O / W emulsion is formed by dispersing the hydrophobic phase using a surfactant or a polymer dispersant in the aqueous monomer solution before the polymerization, and the monomer concentration in the aqueous monomer solution is 30% by weight. %, Preferably 35 to 60% by weight.

Examples of the surfactant include anionic surfactants, for example, sulfates having 10 to 18 carbon atoms such as alkylbenzene sulfonates, higher alcohol sulfates, polyoxyethylene alkyl sulfates, and nonionic surfactants having an HLB of 7 or more. Activators, for example, alkyl ethers such as polyoxyethylene lauryl ether and polyoxyethylene alkyl phenyl ether, sorbitan monolaurate, sorbitan polyoxyethylene laurate, polyoxyethylene glycerin stearate, polyethylene glycol monostearate, polyoxy Fatty acid esters such as ethylene rosin ester can be used.

As the polymer dispersant, partially saponified polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol, polyethylene oxide, hydroxyethyl cellulose and the like can be used. The surfactant or the polymer dispersant is used in an amount of 0.001 to the total amount of the monomers in the aqueous monomer solution.
It is preferably used in an amount of from 20 to 20% by weight, particularly preferably from 0.1 to 10% by weight.

In the present invention, known polymerization initiators can be used, for example, ammonium persulfate, potassium persulfate, hydrogen peroxide, t-butyl hydroperoxide, 2,2'-azobis (amidinopropane) )) And the like. The amount of the polymerization initiator used is 0.01 to 10% by weight based on the total amount of the monomers in the monomer aqueous solution.
Is preferred.

In the present invention, the O / W emulsion may be prepared in any manner. For example, the O / W emulsion may be polymerized with the above-mentioned water-soluble polymerizable monomer and, if necessary, other monomers, a crosslinking agent and a surfactant or a polymer dispersant. An aqueous solution containing an initiator is prepared, and a hydrophobic organic solvent is added thereto, followed by stirring and O / W
Form an emulsion.

The hydrophobic organic solvent used here is not particularly restricted but includes, for example, aliphatic hydrocarbons such as n-pentane, cyclopentane, n-hexane, cyclohexane, n-heptane, methylcyclohexane, petroleum ether, ligroin, gasoline and the like. Hydrogen, benzene, aromatic hydrocarbons such as toluene, n-butyl alcohol, aliphatic alcohols having 4 to 6 carbon atoms such as n-amyl alcohol, aliphatic ketones such as methyl ethyl ketone and methyl isobutyl ketone;
Examples thereof include fatty acid esters such as ethyl acetate and methyl propionate, and these can be used alone or as a mixture of two or more. The addition amount of the hydrophobic organic solvent is preferably from 1 to 200% by weight, particularly preferably from 2 to 50% by weight, based on the aqueous monomer solution.

The above O / W emulsion is preferably prepared by
Polymerize at 130 ° C. The polymer thus polymerized is pulverized after polymerization, dried with a hot-air drier, a reduced-pressure drier, or the like, and further subjected to pulverization and granulation as required, before use. Further, in the same manner as the conventional water-absorbing agent, the surface of the particles can be further cross-linked by using the above-mentioned cross-linking agent, thereby improving the water absorption rate and strengthening the gel strength.

By using the method of the present invention, the apparent specific gravity is small, the elasticity is high, the water absorbing ability and the air permeability are high,
In addition, a porous polymer having a high water absorption rate and a high gel strength can be obtained. Therefore, the porous polymer of the present invention can be used for sanitary napkins, disposable diapers, sanitary cotton, poultices and the like.

Further, because of its high gel strength, it can be used as a water retention agent for agricultural and horticultural use, a water stopping agent for civil engineering construction, a solidifying agent for ooze, a moisture absorbing and releasing wallpaper, and the like. Furthermore, it can also be used for cosmetics and dew-preventing agents, which are important for their shape, elasticity and air permeability.

Further, conventional polyacrylic acid-based water-absorbing resins cannot absorb organic solvents such as alcohols,
The porous polymer of the present invention can absorb not only methanol, ethanol, and isopropanol, but also ethyl acetate, methyl salicylate, menthol, etc., and has an excellent absorption capacity, and also has a high absorption rate, cataplasm, poultice,
By using it for disinfecting cotton, etc., it can exhibit the performance not found in conventional water-absorbing polymers, and can greatly expand the range of use.

[0023]

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

Example 1 An aqueous solution obtained by dissolving 43 parts of sodium hydroxide in 130 parts of water and adding 100 parts of acrylic acid (AA) thereto was added with 0.16 part of ammonium persulfate and partially saponified polyvinyl alcohol (Nihon Gosei Co., Ltd.). GH-17) 4 parts, methylene bisacrylamide 0.2 part, and cyclohexane 54 parts were added and stirred, and nitrogen gas was blown in to drive out dissolved oxygen to prepare an O / W emulsion of an aqueous monomer solution. To this, 0.03 part of L-ascorbic acid was added to form 10 to 100.
The resulting mixture was allowed to undergo standing polymerization at a temperature of ℃ ° C. to obtain a gel-like hydropolymer. After the gel-like hydropolymer was roughly crushed, it 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 the powder, a mixture of 2 parts of colloidal silica (20% aqueous solution of Snowtex O manufactured by Nissan Chemical) and 4 parts of methanol was added and dispersed, and 0.24 part of glycidol was added to 2.10 parts of water. The solution dissolved in 4 parts was added and stirred, and the resulting mixture was heated and dried with a hot air drier at 180 ° C. for 30 minutes to perform a surface treatment to obtain a porous polymer.

Example 2 Example 1 was repeated except that 0.1 part of sodium dodecylbenzenesulfonate was used instead of partially saponified polyvinyl alcohol, 40 parts of hexane was used instead of cyclohexane, and 0.2 part of glycidol was used instead of methylenebisacrylamide. Polymerization and surface treatment were performed in the same manner as described above to obtain a porous polymer.

Example 3 Acrylic acid 2 instead of partially saponified polyvinyl alcohol
5 parts of Na salt of a 7: 3 copolymer of ethylhexyl ester-acrylic acid, polyethylene glycol 400 diacrylate 0.4 in place of methylene bisacrylamide
Parts and 30 parts of ethyl acetate instead of cyclohexane, polymerization and surface treatment were carried out in the same manner as in Example 1 to obtain a porous polymer.

Example 4 Instead of 100 parts of acrylic acid, 80 parts of acrylic acid and 20 parts of dimethylaminoethyl methacrylate (DM) were used, and 30 parts of sodium hydroxide were used instead of 43 parts of sodium hydroxide.
Polymerization and surface treatment were carried out in the same manner as in Example 1 except that 0.2 parts of polyoxyethylene sorbitan monostearate was used instead of partially saponified polyvinyl alcohol to obtain a porous polymer.

Example 5 Instead of 100 parts of acrylic acid, 80 parts of acrylic acid and 20 parts of acrylamidomethylpropanesulfonic acid were used.
Polymerization and surface treatment were carried out in the same manner as in Example 1 except that 34 parts of sodium hydroxide was used instead of 43 parts, and 0.3 parts of polyethylene glycol monolaurate was used instead of partially saponified polyvinyl alcohol. Thus, a porous polymer was obtained.

COMPARATIVE EXAMPLE 1 43 parts of sodium hydroxide was dissolved in 130 parts of water, and 100 parts of acrylic acid (AA) was added thereto. 0.16 parts of ammonium persulfate and 0.2 parts of methylenebisacrylamide were added to an aqueous solution obtained by adding 100 parts of acrylic acid (AA). In addition, the mixture was stirred and blown with nitrogen gas to drive out dissolved oxygen, and 0.03 parts of L-ascorbic acid was added thereto, followed by standing polymerization at 10 to 100 ° C to obtain a gel-like hydropolymer.

After crushing this gel-like hydropolymer,
It was dried with a hot air drier at 0 ° C., pulverized, and sieved with an 18-mesh wire net to obtain a 18-mesh passed product. This powder 40
A mixture of 2 parts of colloidal silica (20% aqueous solution of Snowtex O manufactured by Nissan Chemical Industries, Ltd.) and 4 parts of methanol was added to and dispersed therein, and a solution prepared by dissolving 0.24 part of glycidol in 2.4 parts of water was added thereto. The mixture was stirred. The obtained mixture was heated and dried with a hot air dryer at 180 ° C. for 30 minutes to obtain a water-absorbing polymer.

Comparative Example 2 Comparative Example 1 was repeated except that 80 parts of acrylic acid and 20 parts of dimethylaminoethyl methacrylate (DM) were used instead of 100 parts of acrylic acid, and 30 parts of sodium hydroxide were used instead of 43 parts of sodium hydroxide. Perform polymerization and surface treatment in the same manner,
A water-absorbing polymer was obtained.

Comparative Example 3 In place of 100 parts of acrylic acid, 80 parts of acrylic acid and 20 parts of acrylamidomethylpropanesulfonic acid were used.
Polymerization and surface treatment were carried out in the same manner as in Comparative Example 1 except that 34 parts of sodium hydroxide was used instead of 43 parts, to obtain a water-absorbing polymer.

Application Examples Porous polymers obtained in Examples 1 to 5 and Comparative Example 1
Table 1 shows the water absorption capacity, water absorption rate, gel strength, and methanol absorption of the water-absorbing polymers obtained in Nos. 1 to 3.

Table 1 High Specific Gravity Water Absorption Ratio Water Absorption Rate Gel Strength Methanol Polymer 2 min 20 min Absorbance Example 1 0.137 7.1 7.2 542 560 〃 2 0.25 48 6.1 7.0 465 470 〃 3 0.244 6.7 8.3 458 600 〃 4 0.15 53 5.3 6.5 6.5 378 980 ５ 5 0.347 5.5 5.5 6.0 589 340 Comparative Example 1 0.8 40 3.6 6.3 136 0 〃 2 0.7 22 1.5 5.1 224 50 〃 3 0.9 64 4.5 7.5 175 0

In the applied examples, the water absorption capacity, water absorption rate, and gel strength were measured as follows. ○ Water absorption capacity 200 g of 0.9% saline solution was added to 0.5 g of the polymer powder, and after 1 hour, the weight of the water-absorbed resin which was filtered through a 200-mesh wire net was weighed, and this was divided by the weight of the powder to absorb water. Find the magnification.

Water absorption rate (g / 0.3 g) As a measuring device, a G1 glass filter having a diameter of 7 cm and a test tube with a scale of 1.4 cm in diameter connected with a U-shaped glass tube were used. Spread 0.3 g of the polymer powder evenly on a glass filter, add artificial urine to the same water level, add 2 minutes,
The amount (g) absorbed after 0 minutes is measured by reading the drop in water level. Artificial urine was 1.94 g urea, 0.80 g salt,
0.11 g of magnesium sulfate, 0.06 of calcium chloride
g is dissolved in 97.09 g of pure water to make 100 g.

Gel strength (g / cm ² ) ² g of polymer powder was weighed and placed in a 200 ml beaker.
After 2 g of methanol is added and immersed, 40 g of pure water is added at a stretch and stirred to form a water-absorbing gel. Thereafter, a columnar adapter having a diameter of 6 cm is placed on the water-absorbing gel in the beaker, compressed with Tensilon, and the strength at which the gel starts to flow is measured. The gel strength is represented by the stress per unit area of the cylinder (g / cm ² ).

Methanol absorption rate (%) 20 g of methanol was added to 1 g of the polymer powder, and after 1 hour, the weight of the absorbed methanol was filtered through a 200-mesh wire gauze, and the weight was divided by the weight of the powder. The absorption rate (%) was determined.

[0040]

According to the present invention, the water absorption capacity, the water absorption rate and the gel strength are good, and all the properties are well-balanced, and the polyacrylic acid-based water-absorbing polymer absorbs a considerable amount of methanol which is not absorbed. A unique resin can be obtained.

Claims (1)

(57) [Claims] In producing a porous polymer, a dispersion phase is a hydrophobic phase and a continuous phase is an aqueous phase containing at least one water-soluble polymerizable monomer by using a surfactant or a polymer dispersant. A method for producing a porous polymer, comprising forming an O / W emulsion, polymerizing and drying the emulsion.