JPH11106439A - Water-based acrylic resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject resin that forms water-resistant coating film when it is cross-linked or hardened with a reactive compound that is dispersible or soluble in water as an amino resin or epoxy resin by using a specific copolymer as a main component. SOLUTION: This objective resin is obtained by copolymerizing (A) 100 pts.wt. of a hydroxyl group-containing (meth)acrylic monomer as hydroxyethyl acrylate with (B) 30-250 pts.wt. of a styrenic monomer as styrene as essential components, then adding (C) 0.05-30 wt.%, based on the resultant copolymer, of a hydrolyzable silyl group-bearing compound as γ-glycidoxypropyltrimethoxysilane to the resultant copolymer so that the hydroxyl group value may become 100-300 mg KOH/g and the acid value may reach <=40 mg KOH/g.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a binder for products such as woven fabrics, nonwoven fabrics and papers using materials having a particularly high polarity, for example, cellulose fibers, glass fibers and polyvinyl alcohol fibers. The present invention relates to a crosslinkable and curable aqueous resin that can be used as a coating agent or a treating agent.

[0002]

2. Description of the Related Art Binders for products such as woven fabrics, non-woven fabrics and papers using fibers such as cellulose fibers, glass fibers and polyvinyl alcohol fibers.
The following technology is known as an aqueous resin used as a coating material or a coating agent.

Hydroxyalkyl (meth) acrylates, optionally used aliphatically unsaturated carboxylic acids,
Lipophilic unsaturated monomer, and an unsaturated monomer having a functional group selected from an epoxy group, an N-methylol group, an N-methylol ether group, and two or more vinyl groups; Aqueous emulsion obtained by copolymerization using as an emulsifier. (JP-A-6-107713) A polycarboxylic acid or polyol containing at least two carboxyl groups, acid anhydride groups, or salts thereof,
And a curable aqueous composition containing a phosphorus (III) -containing accelerator. (JP-A-6-184285) Emulsion polymerization of a monomer mixture containing a hydroxyl group-containing monomer,
N-alkoxymethylation (meth) in the presence of this polymer
An emulsion polymer obtained by emulsion polymerization of a monomer mixture containing acrylamides. (JP-A-7-145344)

[0004] All of the above resins are used as a reactive curable nonwoven fabric binder or a film-forming resin in which an amino resin can be used in combination as a curing agent.

[0005]

However, since it is synthesized using an emulsifier having a polyoxyethylene group described in JP-A-6-107713, the resulting aqueous resin has insufficient heat resistance. For example, nonwoven fabrics and glass papers prepared by coating or impregnating with such a resin have a problem that the strength is significantly reduced under high temperature conditions.

When a polymer having a carboxyl group at a certain concentration or higher as disclosed in Japanese Patent Application Laid-Open No. 6-184285 is used, the formed film has insufficient alkali resistance. Nonwoven fabrics, glass papers, and the like prepared by performing coating, impregnation, or the like using a resin have a problem that the strength after immersion in an alkaline solution is greatly reduced.

Further, Japanese Patent Application Laid-Open No. 6-107713 (without using a carboxyl group-containing monomer) and Japanese Patent Application Laid-Open
According to the technique described in JP-A-145344, alkali resistance is improved, but there is still room for improvement in water resistance.

Further, the aqueous resin according to the prior art described above sometimes causes a problem in terms of aging stability when a commercially available aqueous resin is blended and used.

An object of the present invention is to provide an alkali resin, water resistance and heat resistance when cross-linked and cured by using a water-dispersible and soluble reactive compound such as an amino resin such as melamine and an epoxy compound. It is an object of the present invention to provide a water-based resin which is an acrylic water-based resin for forming a film and has good stability over time even when mixed with an existing water-based resin.

[0010]

SUMMARY OF THE INVENTION The present invention comprises, as a main component, a copolymer obtained by polymerizing a monomer having a hydroxyl group-containing (meth) acrylic monomer and a styrene monomer as essential components. An acrylic water-based resin containing the copolymer, wherein the copolymer has a hydroxyl value of 100 to 300 mgKOH / g, an acid value of 40 mgKOH / g or less, and a hydrolyzable silyl group-containing compound is added. The present invention relates to a water-based acrylic resin.

A resin having such a composition is disclosed in
And copolymerization of an unsaturated monomer having a functional group selected from an epoxy group, an N-methylol group, an N-methylol ether group and two or more vinyl groups as described in JP-A-107713. There is no need to perform copolymerization of N-alkoxymethylated (meth) acrylamides as described in JP-A-145344, and a reactive compound that can be dispersed and dissolved in water such as an amino resin such as melamine and an epoxy compound is used. By cross-linking, it is possible to obtain an acrylic water-based resin that forms a film having excellent properties in terms of alkali resistance, water resistance, heat resistance and the like. By the addition of an alkoxysilyl group-containing compound, a strong hydrophilic group on the surface,
For example, the adhesion to a substrate having a hydroxyl group can be further improved.

In the present invention, the resin has a hydroxyl value of 100
In the following cases, the hydrophilicity is insufficient and the stability of the water-based resin is reduced. When it is 300 or more, the hydrophilicity becomes too high and the water resistance of the formed film is reduced. When the acid value is 40 or more, the alkali resistance of the film decreases.

Here, the acrylic resin is acrylic acid,
The term "aqueous resin" means a polymer dissolved or dispersed in an emulsion state in a solvent containing water as a main component, which means a polymer mainly composed of methacrylic acid or a monomer which is an ester thereof. The term “(meth) acrylic acid derivative” is used to mean one or both of an acrylic acid derivative and a methacrylic acid derivative.

In the copolymer, at least 30 to 250 parts by weight of the styrene monomer is copolymerized with respect to 100 parts by weight of the (meth) acrylic monomer containing a hydroxyl group. It is preferable that the hydrolyzable silyl group-containing compound is added to the polymer in an amount of 0.05 to 30% by weight, and the acrylic water-based resin according to claim 1 is obtained by such a composition. Can be.

[0015] Within such a range, an aqueous resin having the effects intended by the present invention can be stably obtained, and the storage stability will be excellent.

In the acrylic water-based resin of the present invention, it is possible to copolymerize other monomers other than those described above, and it is necessary to adjust the properties, hydroxyl value, etc. by copolymerizing such monomers. And the copolymerizable amount is (meth)
Maximum 350 to 3 per 100 parts by weight of acrylic monomer
It is about 60 parts by weight.

The acrylic water-based resin of the present invention is an acrylic resin having a hydroxyl group in a copolymer obtained by polymerizing a monomer containing a hydroxyl group-containing (meth) acrylic monomer and a styrene monomer as essential components. A water-based resin, wherein the copolymer has a hydroxyl value of 100 to 300 mgKOH / g and an acid value of 4
0 mgKOH / g or less, characterized in that a hydrolyzable silyl group-containing monomer is copolymerized.

Even when the hydrolyzable silyl group is directly bonded to the copolymer by copolymerization, an acrylic water-based resin having the same effect as the acrylic water-based resin according to claim 1 can be obtained. That is, by introducing a hydrolyzable silyl group such as an alkoxysilyl group into the molecule of the copolymer, the copolymer molecule is formed by condensation of silanol groups generated by hydrolysis during or after drying of the aqueous resin. It is crosslinked by a siloxane bond, or the adhesion to an oxide such as glass is greatly improved. As a result, the water resistance, alkali resistance, and heat resistance of the film are greatly improved, and the physical properties of nonwoven fabric, glass paper, and the like obtained using this resin are further improved.

The acrylic water-based resin according to claim 3 is:
Further, a compound containing a hydrolyzable silyl group-containing compound may be added.

According to the third aspect of the present invention, the copolymer may be a hydroxyl group-containing (meth) acrylic monomer.
It is preferable that at least 30 to 250 parts by weight of the styrene monomer and 0.05 to 30 parts by weight of the hydrolyzable silyl group-containing monomer are copolymerized with respect to 0 parts by weight. .

The acrylic water-based resin of the present invention can exhibit the intended effect by adding a reactive compound which can be dispersed and dissolved in water, such as an amino resin such as melamine, or an epoxy compound, to form a crosslink. Become.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The raw materials used in the present invention and the method for producing the aqueous resin of the present invention will be described. As the hydroxyl group-containing (meth) acrylic monomer used in the present invention, a hydroxyalkyl (meth) acrylate is used. More specifically, hydroxyethyl acrylate and hydroxyethyl methacrylate can be exemplified as typical compounds thereof, and one or more of these may be used alone or as a mixture.

In addition to the above compounds, other hydroxyl group-containing monomers can be used in combination. Examples of such monomers include hydroxyethyl vinyl ether.

Examples of the styrene monomer include styrene, α-methylstyrene, vinyltoluene and the like, and one or more of these may be used alone or as a mixture.

The monomers constituting the acrylic water-based resin of the present invention include, in addition to the above-mentioned hydroxyl group-containing (meth) acrylic monomers and styrene monomers, various monomers for adjusting and improving various properties. Copolymerizing other monomers is a desirable embodiment.

As such a monomer, a so-called vinyl polymerizable monomer can be used.
Examples thereof include monomers having a nitrile group such as methacrylate, acrylonitrile, and methacrylonitrile; vinyl halides such as vinyl chloride; vinylidene halides such as vinylidene chloride; vinyl alcohol derivatives such as vinyl acetate; and vinyl ethers. In addition, two or more monomers can be freely selected and used in combination according to the required properties.

In the present invention, it is particularly preferable to use an acrylic monomer. As the acrylate, an alkyl acrylate, specifically, methyl acrylate, ethyl acrylate, n-butyl acrylate, 2-ethylhexyl Examples include acrylate, isobutyl acrylate, and the like, and monomers obtained by adding a functional group to these. Further, as the methacrylate, alkyl methacrylate, specifically methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, lauryl methacrylate, methoxydiethylene methacrylate,
Examples include methoxypolyethylene glycol methacrylate and the like, and monomers having a functional group added thereto.

The hydrolyzable silyl group described in claim 3 is preferably an alkoxysilyl group, and examples of the monomer having an alkoxysilyl group include vinyltriethoxysilane, vinyltrimethoxysilane, and vinyltris (2-methoxy). Ethoxy) silane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltris (2-methoxyethoxy) silane, vinyltriacetoxysilane, 4- (3-trimethoxysilylpropyl-benzyl) styrene sulfonate, 3-acryl Oxypropyltrimethoxysilane, allyltriethoxysilane, allyltrimethoxysilane, vinylmethyldiethoxysilane, vinyldimethylethoxysilane, vinylmethyldiacetoxysilane, 3-methylacryloxypropyl Chill - diethoxy silane, 3-acryloxypropyl dimethyl methoxy silane and the like.

In the copolymers according to the first and third aspects of the present invention, a monomer having an acidic group may be further copolymerized. The stability of the aqueous resin can be improved by copolymerizing such a monomer having an acidic group and bonding the acidic group or a salt thereof to a target copolymer molecule. However, when the acid value is increased, the alkali resistance of the formed film is reduced. Therefore, it is necessary that the amount of these copolymers does not exceed the range of the acid value as described in claims 1 and 3.

The acidic group-containing monomer as described above includes
A monomer having an acidic group such as a carboxyl group or a sulfonic acid group can be used, and specific examples of the monomer having a carboxyl group include acrylic acid, methacrylic acid, itaconic acid, maleic acid, and fumaric acid. Further, examples of the monomer having a sulfonic acid group include styrene sulfonic acid.

As the hydrolyzable silyl group-containing compound to be added in the present invention, a compound having an alkoxysilyl group is preferably used, and a commercially available compound called a silane coupling agent can be used. Specifically, γ-aminopropyltriethoxysilane, β-aminoethyltriethoxysilane, γ-aminopropylmethyldiethoxysilane, N- (β-aminoethyl) γ-aminopropyltrimethoxysilane, N- (β- Aminoethyl) γ-aminopropyltriethoxysilane, N- (β
-Aminoethyl) γ-aminopropylmethyldimethoxysilane, β-phenylaminopropyltrimethoxysilane, γ-cyclohexylaminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ
-Mercaptopropylmethyldimethoxysilane, γ-mercaptopropyltriethoxysilane, γ-mercaptopropylmethyldiethoxysilane, N-phenyl-γ
-Aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane and the like. In the present invention, these can be used alone or in combination of two or more. These silane coupling agents are different from the hydrolyzable silyl group-containing monomer in that they are not bonded to the molecules constituting the resin by polymerization, and should be added to the resin in which the hydrolyzable silyl group-containing monomer is copolymerized. Is also possible. In particular, among the above hydrolyzable silyl group-containing compounds, use of a compound having a reactive functional group such as a glycidyl group or an amino group is preferable because good curing characteristics can be obtained.

A compound having a reactive functional group such as an N-methylol group can be used as the amino resin to be added to the acrylic water-based resin of the present invention and used for crosslinking the copolymer molecule. Melamine resin, urea resin and the like can be exemplified as typical ones. As the epoxy compound, a derivative of glycidyl alcohol is exemplified as a suitable compound, and specifically, a commercially available product such as Denacol series (manufactured by Nagase Kasei Co., Ltd.) can be used. Also,
Blocked isocyanate compounds can also be used as crosslinking agents.

In the acrylic water-based resin of the present invention,
In order to improve properties such as heat resistance, water resistance, and alkali resistance, a functional group such as a methylol group or an epoxy group capable of reacting with a hydroxyl group or a carboxyl group present in a polymer molecule in addition to the above-described monomer is used. It is also possible to copolymerize the monomers having.

The acrylic water-based resin of the present invention can be produced by a method well known to those skilled in the art, and may be either one-stage polymerization or multi-stage polymerization.

As the initiator for initiating the polymerization of the above-mentioned monomers, known initiators can be used. The use of water-soluble initiators such as potassium persulfate and ammonium persulfate is preferred, but water-insoluble initiators such as azobisisobutyronitrile, benzoyl peroxide, MEK peroxide, t-butyl hydroperoxide, etc. Can be used. Further, a redox catalyst comprising a combination of a radical generator and a sulfite can also be used. Furthermore, it is also possible to use these persulfates or peroxides, metal ions and reducing agents such as L-ascorbic acid and ersorbic acid.

In the copolymerization of the acrylic water-based resin of the present invention, it is also a preferable embodiment to use a chain transfer agent. As the chain transfer agent, compounds well known to those skilled in the art can be used, and examples thereof include mercaptans such as lauryl mercaptan and dodecyl mercaptan, nitrites, thiosulfates, and hypophosphites.

No emulsifier is used for producing the acrylic water-based resin of the present invention. In order to further improve the stability of the aqueous resin, it is possible to use a water-soluble polymer compound as long as the water resistance of the film is not reduced, and methyl cellulose, hydroxyethyl cellulose, cellulose derivatives such as carboxymethyl cellulose, and water-soluble polymers can be used. It is optional to use a compound that forms a protective colloid, such as a reactive polyurethane resin, a polyvinylpyrrolidone resin, or polyvinyl alcohol.

[0038]

Embodiments of the present invention will be described below. In this example, an example was shown in which a monomer having an alkoxysilyl group was used as the hydrolyzable silyl group-containing monomer. Example 1 120 parts by weight of distilled water was weighed and charged into a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas inlet tube, and heated until the liquid temperature reached 80 ° C. while blowing in nitrogen gas. I do. After the liquid temperature reaches 80 ° C., a solution in which 2 parts by weight of sodium persulfate is dissolved in 8 parts by weight of water is added. Then, hydroxyethyl acrylate (HEA)
40 parts, 40 parts of styrene (ST), 19 parts of n-butyl acrylate (BA) and 1 part of γ-methacryloxypropyltrimethoxysilane, 5 parts of a 5% aqueous sodium hydroxide solution 8 parts, and 2-part 5 parts of a 2% aqueous solution of mercaptoethanol was added dropwise over 3 hours. Thereafter, the mixture was maintained at 80 ° C. for 1 hour, and then 2 parts of a 10% aqueous solution of di-t-butyl peroxide and 2 parts of a 10% aqueous solution of Rongalite were added, and further maintained at 80 ° C. for 1 hour. After the temperature of the obtained liquid was cooled to about room temperature, the pH was adjusted to a range of 7 to 8 with 25% aqueous ammonia.

Examples 2 to 5 Aqueous resin liquids were synthesized in the same manner as in Example 1 according to the formulations shown in Table 1 (Examples 2 to 5). The acrylic aqueous resin obtained in Example 5 was added with 1% by weight of γ-glycidoxypropyltrimethoxysilane based on the solid content of the resin, and subjected to the following evaluation experiments. Abbreviations of compounds other than those used in Example 1 are as follows.

(Comparative Examples 1 to 5) Polymerization was carried out in the same manner as in Example 1 according to the formulation described in Table 1 to obtain an acrylic water-based resin. Comparative Example 1 is an example in which the hydroxyl value is lower than the range of the present invention, Comparative Example 2 is an example in which the acid value is higher than the range of the present invention,
Comparative Example 3 is an example in which the amount of the styrene monomer used is lower than the range of the present invention. Comparative Examples 4 and 5 are examples in which an alkoxysilyl group-containing monomer was not blended and experiments were performed to evaluate polymerization stability and water resistance.

[0041]

[Table 1]

(Evaluation) Trimethylolmelamine equivalent to 15% by weight based on the solid content of the resin was added to the acrylic water-based resin obtained in each of Examples and Comparative Examples to prepare a sample solution. Comparative Example 5 was poor in stability, and was not evaluated. The sample liquid was diluted with water so that the total solid content concentration was 15% by weight, impregnated into a glass fiber nonwoven fabric (glass fiber length: 24 mm) containing 15% pulp, and dried at 150 ° C. for 10 minutes. Treated non-woven fabric,
A test sample of 100 mm × 15 mm was prepared.

(1) Evaluation of Adhesion The treated nonwoven fabric as the above test sample was subjected to a tensile test using Tensilon to evaluate the adhesion for fixing the fibers. Test conditions: 25 ° C, crosshead speed: 100
mm / min.

(2) Evaluation of heat resistance After heating the test sample at 200 ° C. for 3 minutes,
Perform the same test as the adhesion test of (1) in an atmosphere of
The heat resistance was evaluated.

(3) Evaluation of Water Resistance The test sample was immersed in water at room temperature for 5 hours, and then (1)
The evaluation was performed under the same conditions as the evaluation of the adhesion.

(4) Evaluation of Alkali Resistance The test sample was immersed in 2% sodium hydroxide at room temperature for 5 hours, and then evaluated under the same conditions as in (1) Evaluation of Adhesion.

(Evaluation Results) Examples 1 to 5, Comparative Examples 1 to 4
Table 2 shows the evaluation results of the test samples obtained by using. From these results, it is clear that the results of the examples are all good, but the comparative example has the following problems and is not sufficient in characteristics. -Those using a large amount of styrene (Comparative Example 1) have adhesive properties,
Heat resistance is insufficient. -The example with a high acid value (Comparative Example 2) has greatly reduced alkali resistance. -Those using a small amount of the styrene-based monomer (Comparative Example 3) have insufficient heat resistance. -Those having a hydroxyl value exceeding 300 (Comparative Example 4) have low water resistance similarly to those having a high acid value. -In the case where the hydroxyl value is less than 100 (Comparative Example 5), the stability of the aqueous dispersion is poor.

[0048]

[Table 2]

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Claims (5)

[Claims] 1. An acrylic water-based resin containing, as a main component, a copolymer obtained by copolymerizing a monomer containing a hydroxyl group-containing (meth) acrylic monomer and a styrene monomer as an essential component. The copolymer has a hydroxyl value of 100 to 300 mg KOH /
g, an acid value of 40 mg KOH / g or less, and an acrylic water-based resin to which a hydrolyzable silyl group-containing compound is added. 2. The method according to claim 1, wherein the copolymer contains the hydroxyl group-containing (meth)
At least 30 to 250 parts by weight of the styrene-based monomer is copolymerized with respect to 100 parts by weight of the acrylic monomer, and the hydrolyzable silyl group-containing compound is based on the copolymer. The acrylic water-based resin according to claim 1, which is added in an amount of 0.05 to 30% by weight. 3. An acrylic aqueous resin containing, as a main component, a copolymer obtained by copolymerizing a monomer having a hydroxyl group-containing (meth) acrylic monomer and a styrene monomer as essential components. The copolymer has a hydroxyl value of 100 to 300 mg KOH /
g, an acrylic water-based resin having an acid value of 40 mgKOH / g or less and copolymerized with a hydrolyzable silyl group-containing monomer. 4. The acrylic water-based resin according to claim 3, further comprising a hydrolyzable silyl group-containing compound. 5. The method according to claim 1, wherein the copolymer contains the hydroxyl group-containing (meth)
At least 30 to 250 parts by weight of the styrene monomer and 0.05 to 30 parts by weight of the hydrolyzable silyl group-containing monomer were copolymerized with respect to 100 parts by weight of the acrylic monomer. The acrylic water-based resin according to claim 3, which is a resin.