JPH02265909A - Water-swellable resin composition - Google Patents

Abstract

PURPOSE:To obtain a water-swellable resin composition having a high rate of swelling, a high degree of swelling, high water absorption stability, high insolubility in water, etc., by mixing a water-swellable resin comprising a water- soluble salt of a specified copolymer with a medium. CONSTITUTION:The title composition is obtained by adding a medium to a hydrophobic water-swellable resin comprising an alkali metal salt of a copolymer of an alpha,beta-ethylenically unsaturated group-terminated hydrophobic polymer chain with a monomer based on (meth)acrylic acid and polyethylene glycol mono(meth)acrylate and/or polyethylene glycol monoalkyl ether mono(meth) acrylate and/or a hydrophilic amine salt of this copolymer, wherein the polyethylene glycol monoalkyl ether mono(meth)acrylate amounts to 40-70wt.% of the copolymer. The hydrophobic water-swellable resin excels in an affinity for the medium and dispersion stability in the medium, has a high rate of swelling, a high degree of swelling, high water absorption stability, high insolubility in water, etc., and is useful for many uses.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a water-swellable resin composition, more specifically a sealing material, a water running prevention agent, a waterproofing agent, a water retention agent, an anti-condensation agent, a sweat-absorbing material, The present invention relates to a water-swellable resin composition useful as a material for sanitary products and the like.

(Prior art and its problems) Conventionally, water-swellable resins include, for example, those obtained by crosslinking water-soluble resins, those obtained by graft polymerization of water-soluble monomers on starch, etc., and those composed of hydrophilic resins and hydrophobic resins. Block copolymers and the like are known.

The crosslinked product of the above-mentioned water-soluble polymer exhibits high swelling property when the crosslinking density is low, but it elutes in water, whereas when the crosslinking density is high, it does not elute in water but has a problem that the swelling property decreases. High swelling and excellent water insolubility are not compatible. In addition, since it is difficult to use alone, it is used after being dispersed in an organic medium, but there is a considerable problem that the affinity for the organic medium is low.

In addition, since the grafted product is based on a natural product, it is degradable by microorganisms, has the disadvantage of lacking long-term stability in a water-absorbed state, and also has a problem of low affinity for organic media.

In addition, block copolymer type products have excellent swelling properties, water absorption stability, affinity for organic media, etc., but have problems in their production method and have the disadvantage that their fields of application are limited.

As a solution to the above problem, the present inventor has proposed α,
A hydrophobic polymer chain having a β-ethylenically unsaturated group,
proposed a water-swellable resin consisting of an alkali metal salt and/or a hydrophilic amine salt of a copolymer with a monomer containing meth)acrylic acid as a main component (see Japanese Patent Application No. 1-27682). Although water-swellable resins have solved various problems, the problem remains that the dispersion stability in organic solvents and the rate of water swelling when in contact with water are somewhat unsatisfactory.

Therefore, an object of the present invention is to provide a water-swellable resin composition that solves the above-mentioned problems.

[Means for solving problems] The above objects are achieved by the present invention as described below.

That is, the present invention comprises a water-swellable resin and a medium, and the water-swellable resin comprises a hydrophobic polymer chain having an a-, β-ethylenically unsaturated group at the end, (meth)acrylic acid, and polyethylene. Alkali metal salts and/or copolymers of glycol mono(meth)acrylates and/or polyethylene glycol monoalkyl ether mono(meth)acrylates (hereinafter referred to as nonionic monomers) with heptamers as main components.
or a hydrophilic amine salt, which is a water-swellable resin composition characterized in that the nonionic monomer accounts for more than 40 to 70% by weight of the copolymer. A water-soluble salt of a copolymer consisting of a hydrophobic polymer chain having a system unsaturated group and a hexamer whose main components are (meth)acrylic acid and a specific amount of nonionic monomer has a high affinity with the medium and It has excellent dispersion stability in water, high swelling rate, swelling degree, water absorption stability, insolubility in water, etc., and is useful for various uses.

(Preferred Embodiments) Next, the present invention will be explained in more detail with reference to preferred embodiments.

The water-swellable resin that mainly characterizes the present invention has α
, a hydrophobic polymer chain having β-ethylenically unsaturated groups and (
It is obtained by copolymerizing meth)acrylic acid and a specific amount of a specific nonionic monomer, and then forming a salt with an alkali metal and/or a hydrophilic amine.

The hydrophobic polymer chain having an α,β-ethylenically unsaturated group at the end used in the present invention is a homopolymer or copolymer of styrene, (meth)acrylic acid ester, acrylonitrile, etc. ) having an α, β-ethylenically unsaturated group such as an acryloyl group.

Such hydrophobic polymer chains are formed by forming 3,3'-azobis-3-cyanobutyric acid, 4,4'-
Azobis-4-cyanovaleric acid, 4.4゛-azobis-4
-cyano-1-pentanol, 2,2'-azobis-2
- A method of polymerization using a polymerization initiator having a functional group such as an azo type such as cyano-propanol, a peroxide type such as hydrogen peroxide, succinic acid peroxide, gel tar acid peroxide, etc., or a method of polymerization using a polymerization initiator having a functional group such as azo type such as cyano-propanol, or thioglycol or thioglycerin. A hydroxyl group or a carboxyl group is introduced at the end of the polymer by a method such as polymerization using a chain transfer agent having a functional group such as thioglycolic acid, thiosuccinic acid, or thiopropionic acid,
Utilizing these functional groups, for example, by reacting (meth)acrylic acid, hydroxyalkyl (meth)acrylate, glycidyl (meth)acrylate, maleic anhydride, etc., α, β-ethylene type Obtained by introducing an unsaturated group.

The hydrophobic polymer chain itself having an α,β-ethylenically unsaturated group at its terminal is called a macromer or macromonomer, and various types are available and can be used in the present invention.

Such hydrophobic polymer chains may have any molecular weight, but if the molecular weight is too low, the resulting water-swellable resin will have high water solubility, and if it is too high, the water-swellability will be insufficient. Therefore, the preferred average molecular weight range is 1,000 to 2.
0,000, preferably in the range of 1,500 to 15,000.

The seven polymers to be copolymerized with the above macromer are mainly composed of (meth)acrylic acid and a nonionic monomer.

The copolymerization ratio of macromer and (meth)acrylic acid is
If the amount of (meth)acrylic acid is too low, the water swelling rate of the resulting copolymer will be insufficient, while if it is too high, the water insolubility of the resulting copolymer will decrease, so the macromer will be It accounts for 2 to 60% by weight, while (meta)
Acrylic acid is preferably used in a proportion ranging from about 20 to 55% by weight in the resulting copolymer.

In addition, as the nonionic monomer, polyethylene glycol mono(meth)acrylate and/or polyethylene glycol monoalkyl ether mono(meth)acrylate (the number of carbon atoms in the alkyl group is 1 to 12) is used, and the polyethylene glycol segment of the nonionic monomer is The molecular weight is preferably about 160 to 10,000. If the molecular weight is less than about 160, the hydrophilicity will be insufficient, while if it exceeds 10,000, the viscosity of the reaction solution during polymerization will be high. Undesirable.

Further, the amount of these nonionic monomers used is preferably in the range of more than about 40% by weight to about 70% by weight of the copolymer finally obtained. If the amount used is less than 40% by weight, the swelling rate may be insufficient. On the other hand, if it exceeds 70% by weight, the degree of water swelling becomes low, which is not preferable.

By using such nonionic monomers in proportions within the above range, the surface of the resulting water-swellable resin is modified, its wettability with water is improved, and its initial swelling rate is improved. Furthermore, the degree of swelling is relatively less reduced even in water containing heavy metal ions such as calcium ions and magnesium ions. Furthermore, by mixing it with the water-swellable resin already proposed by the inventor of the present application, the water swelling rate of the IM resin can be significantly improved.

In addition, other hydrophobic or hydrophilic monomers, such as nonionic monomers such as hydroxyethyl (meth)acrylate, sulfopropyl methacrylate potassium salt, styrene sulfonic acid sodium salt,
2-acrylamido-2-methylpropanesulfonic acid,
Anionic monomers such as mono(2-methacryloyloxyethyl) acid phosphate may be used in combination with the above-mentioned essential monomers. P-divinylbenzole, trimethylolpropane triacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, dipentaerythritol hexaacrylate, 1 mol of dipentaerythritol hexaacrylate and thioglycolic acid (or its soda salt) ) may also be used in combination with a small amount of a polyfunctional monomer such as an addition product with 1 to 3 moles of N,N'-methylenebisacrylamide.

These polyfunctional monomers are used in an amount that accounts for 5% by weight or less, preferably 0.1 to 3% by weight of the resulting copolymer.

Also, (A)-(B)-(A) or [(A)-(B)]
Il or (A)-B), (n indicates a numerical value of 1 or more,
By containing a hydrophobic block copolymer or a hydrophobic graft copolymer represented by A is polystyrene or polymethyl methacrylate and B is polybutadiene or polyisoprene, the reaction system during copolymerization can be improved. It acts as a dispersion stabilizer for ZUMMER to obtain a homogeneous copolymer, and furthermore, in the resulting copolymer, it acts as a physical crosslinking agent or reinforcing agent to connect the hydrophobic polymer chains of the copolymer. Particularly preferred are (A)-(B) because the elution amount of the water-swellable resin in water is reduced.
-(A) type block or (A)-(B) n type graph] copolymer. These block or graft copolymers are used in a proportion of 5% by weight or less, preferably 0.5 to 5% by weight, in the copolymer (water-swellable resin).

The copolymerization of the monomers is preferably carried out in a good solvent for the macromer, such as cyclohexane, toluene, xylene, turpentine, naphthene, methyl ethyl ketone, dioxane, dimethylformamide, or a mixture thereof. The polymerization method itself may be a known solution polymerization method using a radical polymerization initiator, and is not particularly limited.

The carboxyl group in the copolymer thus obtained is replaced with an alkali metal such as lithium, sodium, potassium, etc. or a hydrophilic amine preferably having a boiling point of 150° C. or higher, for example,
The water-swellable resin of the present invention can be obtained by neutralizing with mono-, di-, or triethanolamine. It is not preferable that the hydrophilic amine has a low boiling point, such as ammonia or methylamine, because these ammonia and amines are liberated and the degree of water swelling of the resulting water-swellable resin changes.

The amount of neutralization is 50 mol% to 100 mol%, preferably 60 to 80 mol% of the carboxyl groups in the copolymer,
Excessive use of alkali during neutralization is not preferred since it may cause hydrolysis of the copolymer. Any method may be used for neutralization, but the preferred method is to perform it in a polymerization solvent after copolymerization, since the neutralized copolymer precipitates as fine particles of several μm or less. The water-swellable resin composition of the present invention can be used as it is or by adding necessary additives such as a binder as a coating liquid or an impregnating liquid.

Further, in the present invention, the water-swellable resin can be separated from the dispersion liquid by a known method to form a solid or powder, and then dispersed in another medium.

The medium used in the present invention is a natural or synthetic polymer or a liquid medium that may contain these polymers. Preferred solid media such as natural or synthetic polymers used are natural rubber, polybutadiene, polyisoprene, polyisobutylene, butadiene-styrene copolymer, butadiene-acrylonitrile copolymer,
These include polychloroprene, ethylene-propylene rubber, acrylic polymer, ethylene-vinyl acetate copolymer, polyvinyl butyral resin, silicone rubber, urethane rubber, etc. Copolymers include random copolymers, graft copolymers, and block copolymers. Various copolymers are used, and among them, telechelic type, multi-type, and radial type block copolymers are preferred because they have excellent strength.

In addition, the liquid medium may be blended alone with the water-swellable resin, or may be added to the solid medium to improve flexibility, processability, texture, etc. General organic solvents such as those mentioned above may be used. , water, plasticizer, process oil, oil, liquid paraffin,
Liquid polymers such as vaseline and polyisobutyne are preferred.

The solid medium and liquid medium as described above can be blended alone, but it is also preferable to use them in the form of being dissolved or dispersed in an organic solvent.

Although the water-swellable resin used in the present invention is ionic, it is insoluble in water, and is often insoluble or soluble in organic solvents, and also has the property of not melting. .

Therefore, the water-swellable resin of the present invention is preferably used in the form of a fine powder or as a dispersion in an organic solvent. Therefore, the means for mixing this water-swellable resin with the solid or liquid medium or their organic solvent solution or dispersion is as follows:
Conventionally known dispersing machines and mixers, such as roll mills, Banbury mixers, Nigu, Daysilver, ball mills, and sand mills, can be preferably used.

The essential components constituting the water-swellable resin composition of the present invention are as described above, but various other additives may be optionally added depending on the purpose of use, etc. For example, surfactants, fragrances, etc. , various dyes and pigments, various fillers, ultraviolet absorbers,
Stabilizers, blowing agents, various inorganic salts, various alkaline agents, various acidic agents, etc. are used together in required amounts.

In addition, the water-swellable resin used when blending the above components is
The ionic group may be in a free form or a salt form, which is determined by its intended use. Types with free ionic groups can be neutralized into a salt form during the intermediate or final step of manufacturing the resin composition, or can be made into a salt form with an appropriate alkaline solution depending on the type of ionic group. It is also possible to mix an acidic agent or an acidic agent so that the ionic groups are neutralized when water is absorbed.

Further, the water-swellable resin composition of the present invention can take various forms, and can be broadly classified into solid and liquid at room temperature. In the case of a solid state, it may be in the form of powder, pellet, granule, various molded products, fiber, impregnated product, etc. Furthermore, it may be a so-called master batch or a final product. Such solid products include highly hygroscopic fibers, synthetic leather base materials, water sealants for joints in various buildings and underground structures, paper diapers, sanitary products, water-containing cold pillows, and other sanitary and medical products. Agriculture and forestry products, such as anti-water running agents for optical communications and electric cables, soil water retention agents, water retention agents for seedlings, humidity control materials, sweat and hygroscopic base materials for shoes and their insoles, cold storage materials for fish and fruits, etc. - Examples include marine products, etc.

On the other hand, examples of pasty or liquid products include paints, coating materials, processing agents, and printing inks, and they are particularly useful as paints. For example, if such a paint is applied to the joints, cracks, or joints of various structures, not only will the gaps be filled, but if water tries to enter the area after filling, the water will The formed paint expands further and can completely prevent further water from entering. In particular, since the composition of the present invention repeatedly expands reversibly with water, it is expected to have a long-term waterproof effect. Furthermore, when the liquid composition of the present invention is used as an impregnating agent for various articles, such as woven fabrics and nonwoven fabrics, the properties of these various articles can be modified. Furthermore, when applied to the surface of dew-condensing materials such as various plastic films, glass or metal plates, it exhibits an excellent dew-condensing prevention effect.

(Effects) According to the present invention as described above, a hydrophobic polymer chain having an α,β-ethylenically unsaturated group at the terminal, a monomer whose main components are (meth)acrylic acid and a specific amount of a nonionic monomer, As detailed above, the water-soluble salt of the copolymer has superior advantages due to its structure.

That is, since the hydrophilic group consists of a specific proportion of ionic groups and nonionic groups, the initial water absorption rate or water swelling rate is high, and the water absorption capacity or swelling degree is very high.

Moreover, due to the restraining action of the hydrophobic polymer chains in its structure, it does not substantially dissolve in water or ooze out into water.

Furthermore, since the water-containing swollen product is fixed by the restraint of the hydrophobic polymer chains, it has superior physical strength compared to conventional water-swellable resins using crosslinking points.

(Example) Next, the present invention will be described in more detail with reference to Examples. In the text, parts or percentages are based on weight unless otherwise specified.

8 parts of polymerizable polystyrene with a molecular weight of 7,000 having a methacryloyl group as an a,β-ethylenically unsaturated group at the end, and a molecular weight of 6, having a methacryloyl group as an α,β-ethylenically unsaturated group at the end. 000 polymerizable polybutyl acrylate, 6 parts of acrylic acid, 23.4 parts of sodium acrylate, 60 parts of polyethylene glycol monomethacrylate (PEG molecular weight approximately 300), and α, α'
Add 1 part of azobisisobutyronitrile to cyclohexane/
Mixed solvent 280 with toluene/methyl ethyl ketone/methanol/water ratio of 70/8.5/8.5/lO/3
1 part of a (polystyrene)-(polybutadiene)-(polystyrene) type block copolymer (polystyrene content 30%, molecular weight approximately 200,000) was added and copolymerized to obtain a sol of the present invention. A water-swellable resin was obtained. The degree of water swelling of this resin in pure water was about 15 times, and in seawater it was about 10 times.

Sol of the above water-swellable resin (solid content 30%), dispersion of water-swellable resin of polymerizable polystyrene-polymerizable polybutyl acrylate-sodium acrylate (polystyrene content io%)
, a water swelling degree of approximately 100 times, an average particle diameter of 0.5 μm, a solid content of 35%) and an acrylic rubber solution (solid content of 20%) mainly composed of polybutyl acrylate-1, respectively, with a solid content of 7.
They were mixed in a ratio of 8.2 parts/8.7 parts/13.1 parts to form a water-swellable resin composition of the present invention.

A polyester nonwoven fabric coated with the above composition and dried had a high initial swelling rate and good wettability against seawater, and was useful as a tape for preventing water running in optical communication cables.

Example 2 10 parts of polymerizable polystyrene with a molecular weight of about 7,0000 and having a methacryloyl group as an α,β-ethylenically unsaturated group at the terminal, 5 parts of acrylic acid, 20 parts of sodium acrylate, polyethylene glycol monomethacrylate (PEG with a molecular weight of about 160) ) and 1 part of α,α゛azobisisobutyronitrile in a cyclohexane/toluene/methyl ethyl ketone/methanol/water ratio of 70/8.5/8.5.
/10/3 dissolved in 280 parts of a mixed solvent, and further (polystyrene)-(polybutadiene)-(polystyrene)
0.5 parts of a type block copolymer (polystyrene content: 40%, molecular weight: approximately 100,000) was added and copolymerized to obtain a water-swellable resin of the present invention in the form of a sol. The degree of water swelling of this resin in pure water was about 10 times, and in seawater it was about 8 times.

Separate the above water-swellable resin and convert it into polyethylene.
The agricultural film prepared by blending it at a ratio of 0% had excellent dew condensation prevention properties.

Furthermore, a coating solution prepared by adding a polyurethane resin as a binder to the above-mentioned water-swellable lubricant solution was applied to an agricultural polyethylene film and dried, and the film was similarly excellent in preventing dew condensation.

Example 3 10 parts of polymerizable polymethyl methacrylate with a molecular weight of 1.0.000 having a methacryloyl group as an α,β-ethylenically unsaturated group at the end, and a methacryloyl group as an a,β-ethylenically unsaturated group at the end. with a molecular weight of 5,0
00 polymerizable polystyrene 15 parts, acrylic acid 10 parts,
30 parts of sodium acrylate, polyethylene glycol monomethacrylate (PEG molecular weight approximately 1,000) 4
5 parts and 1 part of α, α′ azobisisobutyronitrile,
It was dissolved in 350 parts of a mixed solvent with a ratio of cyclohexane/toluene/methyl ethyl ketone/methanol/water of 47/10/30/10/3, and further (polystyrene)-(
One part of a polyisobutylene-(polystyrene) type block copolymer (polystyrene content: 15%, molecular weight: approximately 200,000) was added and copolymerized to obtain a sol-like water-swellable resin of the present invention.

The water swelling degree of this resin in pure water is about 25 times,
In seawater, it was about 12 times higher.

Add polyurethane binder to the above resin liquid at a solid content ratio of 30
/70 to prepare a coating solution. The yarn obtained by applying this coating solution to the surface of a polyester yarn in an amount of 75% of the amount of the yarn and drying it had excellent hydrophilicity, and the net made from this yarn was suitable for cultivating seaweed.

Example 4 The solvent composition in Example 1 was changed to cyclohexane/toluene/methyl ethyl ketone/methanol/water = 21.5/
43/21.5/3.0/11, otherwise a water-swellable resin solution was obtained in the same manner as in Example 1. This solution itself has film-forming ability and has a high wetting speed with seawater, so when used as a top coat layer for other water-swellable resins, the water swelling speed of the coating will be significantly improved. Ta.

Application examples include a water running prevention agent for optical communication cables and a surface treatment agent for water-absorbing nonwoven fabrics for diapers.

Applicant: Dainichiseika Industrial Co., Ltd. ~1 and 5""

Claims (8)

[Claims] (1) Consisting of a water-swellable resin and a medium, the water-swellable resin contains a hydrophobic polymer chain having an α,β-ethylenically unsaturated group at the end, (meth)acrylic acid, and polyethylene glycol mono( It is an alkali metal salt and/or a hydrophilic amine salt of a copolymer with a monomer whose main component is meth)acrylate and/or polyethylene glycol monoalkyl ether mono(meth)acrylate, and the above-mentioned polyethylene glycol mono(meth)acrylate and /or polyethylene glycol monoalkyl ether mono(meth)
A water-swellable resin composition characterized in that acrylate accounts for more than 40 to 70% by weight of the copolymer. (2) The molecular weight of the hydrophobic polymer chain is 1,000 to 20,
000 and accounts for 2 to 60% by weight in the copolymer. (3) The water-swellable resin composition according to claim 1, wherein acrylic acid or methacrylic acid accounts for 20 to 55% by weight in the copolymer. (4) The water-swellable resin composition according to claim 1, wherein the hydrophobic polymer chain is a homopolymer or copolymer of styrene, methyl methacrylate, ethyl methacrylate, or acrylonitrile. (5) The water-swellable resin composition according to claim 1, wherein the hydrophilic amine is an amine having a boiling point of 150°C or higher. (6) The water-swellable resin composition according to claim 1, wherein the copolymer contains polyfunctional monomer units accounting for 5% by weight or less of the copolymer. (7) The copolymer accounts for 5% by weight or less of the copolymer (A
)-(B)-(A) or [(A)-(B)]_n or (A)-(B)_n (n indicates a numerical value of 1 or more, A is polystyrene or polymethyl methacrylate, B The water-swellable resin composition according to claim 1, which contains a hydrophobic block copolymer or a hydrophobic graft copolymer represented by polybutadiene or polyisoprene. (8) The water-swellable resin composition according to claim 1, wherein the medium is a plasticizer, a solvent, a resin, or a resin solution.