JPH0931165A - Water-based resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a water-based resin compsn. very short in curing time even in an aq. system and comparatively low in curing temp. SOLUTION: This water-based resin compsn. comprises a water-based resin emulsion as the main component, (a) an epoxy resin as a modifier, (b) a dihydrazide compd. as a curing agent, and (c) at least one of monohydrazide compds., imidazole compds., acid anhydrides, tert. amine compds., carboxylic acids and dicyandiamide compds. as a curing accelerator.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an aqueous resin composition having a very short curing time even in an aqueous system and a relatively low curing temperature.

[0002]

Acrylic resins are widely used as adhesives, paints, fiber treatment agents, etc. because their cured products have remarkably excellent transparency and weather resistance. However, it has a drawback that its long-term durability is insufficient. In order to eliminate such a defect, it has recently been proposed to cure (crosslink) the acrylic resin in the presence of a curing agent. Here, as the curing agent, dibasic acid dihydrazides such as adipic acid dihydrazide, sebacic acid dihydrazide, and dodecane-2-acid dihydrazide, and 2
-Methylimidazole, 2-ethylimidazole, 2-
Imidazole compounds such as ethyl-4-methylimidazole, phthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic acid anhydride, pyromellitic anhydride, chlorendic acid anhydride, acid anhydrides such as dodecenylsuccinic anhydride, diethylenetriamine, A tertiary amine compound such as benzyldimethylamine and a general epoxy resin curing agent such as dicyandiimide are used. Among these, the use ratio of dibasic acid dihydrazide is increasing because it gives a cured product that is highly flexible and hardly cracks.

More recently, various properties such as mechanical properties, abrasion resistance and flexibility of acrylic resin have been further improved,
Further, in order to improve the compatibility between the acrylic resin and a resin additive such as an ultraviolet absorber, an epoxy resin is blended with the acrylic resin as a modifier. For example, Japanese Patent Application Laid-Open No. 1-113476 discloses a resin composition containing an acrylic resin, an epoxy resin, a dibasic acid dihydrazide and dicyandiamide, an imidazole compound and the like. However, the technique described in the publication does not require a curing reaction in an aqueous system, but takes about 30 minutes to 1 hour for curing, and the curing temperature is as high as 180 to 200 ° C. Further, JP-A-4-80280 suggests an aqueous resin composition containing an acrylic resin emulsion, an epoxy resin, and at least one curing agent selected from a dibasic acid dihydrazide and an imidazole compound, and a curing reaction at 80 ° C. Although it is carried out at a relatively low temperature, there is no concrete example in which two kinds of curing agents are used in combination, and in addition, the curing time is very long, about 4 hours. The biggest problem of the curing reaction in an aqueous system in which an acrylic resin and an epoxy resin coexist is that the reaction time is very long.

That is, in these publications, there is no specific example in which a dibasic acid dihydrazide is used in combination with another resin curing agent in an aqueous system in which an acrylic resin is the main component and an epoxy resin as a modifier coexists. Therefore, it is not suggested that the curing reaction can be completed at a relatively low temperature in an extremely short time of several minutes to ten and several minutes.

On the other hand, with the recent increasing demands for environmental protection, water is being used instead of an organic solvent that significantly pollutes factory wastewater when curing acrylic resins, epoxy resins and the like. Therefore, in an aqueous system in which an acrylic resin and an epoxy resin coexist, development of an aqueous resin composition capable of undergoing a curing reaction in a very short time under mild conditions, that is, at a relatively low temperature from room temperature to about 100 ° C. Is desired.

[0006]

As a result of intensive studies to solve the above problems, the present inventor has found that a dihydrazide compound as a curing agent and a specific curing accelerator in a water system in which an acrylic resin and an epoxy resin coexist. Although it has a remarkably long pot life, the curing reaction can be completed in a very short time of about several minutes to several tens of minutes even under mild conditions, that is, at a relatively low temperature of about room temperature to about 100 ° C. Moreover, the resulting cured product retains outstanding transparency and weather resistance, which are preferable properties of acrylic resin, and has surface hardness, long-term durability, mechanical strength, abrasion resistance, flexibility, and resin additive. It has various characteristics such as compatibility at a high level, and furthermore, it is an aqueous resin emulsion other than acrylic resin,
For example, it has been found that similar shortening of the curing time can be achieved even in a coexisting water system of polyvinyl alcohol or the like and an epoxy resin. The present invention has been completed based on such findings.

That is, the present invention comprises an aqueous resin emulsion as a main component, (a) an epoxy resin as a modifier, (b) a dihydrazide compound as a curing agent, and (c) a monohydrazide compound, an imidazole compound as a curing accelerator,
The present invention relates to an aqueous resin composition containing at least one selected from an acid anhydride, a tertiary amine compound, a carboxylic acid and a dicyandiamide compound.

Although the aqueous resin composition of the present invention has a remarkably long pot life, it is extremely short, such as several minutes to ten and several minutes, even under mild conditions, that is, at a relatively low temperature from room temperature to about 100 ° C. It can be cured over time. Moreover, the cured product obtained by curing the resin composition of the present invention retains outstanding transparency and weather resistance which are preferable properties of acrylic resin, and has surface hardness, long-term durability, mechanical strength, and abrasion resistance. , It has various characteristics such as flexibility, compatibility with resin additives, etc.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the aqueous resin composition of the present invention, the aqueous resin emulsion is the main curing component. The aqueous resin emulsion is not particularly limited as long as it is a resin raw material and / or a resin capable of forming an emulsion with water, and examples thereof include acrylic resin and polyvinyl alcohol.

Any known acrylic resin may be used,
Specific examples include those containing at least one acrylic monomer selected from the following non-functional monomers, monofunctional monomers and polyfunctional monomers. Specific examples of the non-functional monomer include, for example,
Methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, (meth)
Tert-butyl acrylate, 2- (meth) acrylic acid
Ethylhexyl, octyl (meth) acrylate, isodecyl (meth) acrylate, lauryl (meth) acrylate, lauryl (meth) acrylate-tridecyl, tridecyl (meth) acrylate, cetyl-stearyl (meth) acrylate, (meth ) Stearyl acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate and the like can be mentioned. Specific examples of the monofunctional monomer include (meth) acrylic acid and (meth)
2-Hydroxyethyl acrylate, 2-hydroxypropyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, tert-butylaminoethyl (meth) acrylate, (meth) acrylic acid Examples thereof include glycidyl and tetrahydrofurfuryl (meth) acrylate. Specific examples of the polyfunctional monomer include, for example, di (meth)
Ethylene acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, decaethylene glycol di (meth) acrylate, pentadeca di (meth) acrylate Ethylene glycol, di (meth) acrylic acid pentacontahector ethylene glycol, di (meth) acrylic acid 1,3-butylene, allyl (meth) acrylate, trimethylolpropane tri (meth) acrylate, tetra (meth) acrylic acid Examples thereof include pentaerythritol and diethylene glycol di (meth) acrylate phthalate. These acrylic monomers are used alone or in combination of two or more. A commercially available acrylic resin can also be used. The acrylic resin of the present invention further includes, for example, vinyl acetate,
Known comonomers copolymerizable with acrylic monomers such as vinyl chloride, styrene, (meth) acrylamide, acrylonitrile, acryloylmorpholine, and acryloguanamine may be contained. These comonomers also
They may be used alone or in combination of two or more. The acrylic resin may be a molded product of any shape after completion of crosslinking (curing), or may be in a monomer state before crosslinking.

Further, polyvinyl alcohol is not particularly limited, but acetoacetylated polyvinyl alcohol and the like can be preferably used.

Among these aqueous resin emulsions,
Acrylic resins are particularly preferred.

In the aqueous resin composition of the present invention, a known epoxy resin may be used as a modifier, and examples thereof include bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol nopolak type epoxy resin and cresol novolak. Type epoxy resin, glycidyl amine type epoxy resin, alicyclic epoxy resin, urethane modified epoxy resin, brominated bisphenol A type epoxy resin, heterocyclic epoxy resin and the like.
Moreover, a commercially available epoxy resin can also be used. The amount of the epoxy resin used is not particularly limited and can be appropriately selected from a wide range depending on the application of the resin cured product to be obtained, but is usually 0.1 to 50 per 100 parts by weight of the acrylic resin in terms of solid content.
The amount may be about part by weight, preferably about 0.5 to 10 parts by weight.

In the aqueous resin composition of the present invention, a dihydrazide compound is used as a curing agent. It is known that a dihydrazide compound generally requires about 1 hour to several hours to react with an epoxy resin at a temperature of 150 to 200 ° C. Therefore, when the dihydrazide compound is used alone, the curing time is not significantly shortened, and the curing time is significantly shortened only when the dihydrazide compound and the specific curing accelerator are used in combination.

The dihydrazide compound is not particularly limited as long as it has two or more hydrazide groups in one molecule, and specifically, for example, oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, Adipic acid dihydrazide, azelaic acid dihydrazide, sebacic acid dihydrazide, dodecanedioic acid dihydrazide, maleic acid dihydrazide, fumaric acid dihydrazide, diglycolic acid dihydrazide, tartaric acid dihydrazide, malic acid dihydrazide, terephthalic acid dihydrazide, isophthalic acid dihydrazide, terephthalic acid Dibasic acid hydrazides such as dihydrazide compounds described in Japanese Patent Publication No. 2-4607, carbohydrazide, 2,
4-dihydrazino-6-methylamino-sym-triazine, poly (meth) acrylic acid hydrazide and the like can be mentioned. Among these, dibasic acid dihydrazide,
Carbohydrazide and the like are preferable, and adipic acid dihydrazide, malonic acid dihydrazide, carbohydrazide and the like are particularly preferable. In the present invention, the dihydrazide compounds may be used alone or in combination of two or more. The amount of the dihydrazide compound used is not particularly limited and can be appropriately selected from a wide range depending on the application of the resin cured product to be obtained, but usually the total amount of acrylic resin and epoxy resin in terms of solid content is 10
It may be about 0.01 to 10 parts by weight, preferably about 0.05 to 5 parts by weight, relative to 0 parts by weight.

In the aqueous resin composition of the present invention, at least one selected from a monohydrazide compound, an imidazole compound, an acid anhydride, a tertiary amine compound, a carboxylic acid and a dicyandiamide compound is used as a curing accelerator. Of these, the monohydrazide compound is a compound that has not been conventionally used as a curing agent for acrylic resins and epoxy resins, and exhibits an excellent curing-accelerating effect when used in combination with the dihydrazide compound in the water system of the present invention. Further, the imidazole compound and the dicine asiamid compound are curing agents known to cause a curing reaction with an acrylic resin or an epoxy resin at 80 to 120 ° C., and with a dihydrazide compound having a curing reaction temperature of 150 to 200 ° C. The reason why the curing time is significantly shortened by the combined use is not yet clear, but it is considered that it is caused by the curing reaction in the water system, the coexistence of the acrylic resin and the epoxy resin, and the like. Furthermore, it is known that the acid anhydride and the tertiary amine compound react with the epoxy resin at room temperature. However, as is clear from the examples described below, the dihydrazide compound and the dihydrazide compound are not detected after curing. It is considered that the above curing agents act competitively.

The monohydrazide compound is not particularly limited as long as it is a compound having one hydrazide group in the molecule. For example, the general formula R-CO-NHNH ₂ (1) [wherein R is a hydrogen atom] Represents an alkyl group or an aryl group which may have a substituent. A monohydrazide compound represented by the formula: Specific examples of the monohydrazide compound of the general formula (1) include, for example, lauric acid hydrazide, salicylic acid hydrazide, form hydrazide, acetohydrazide, propionic acid hydrazide, p-
Examples thereof include hydroxybenzoic acid hydrazide, naphthoic acid hydrazide, and 3-hydroxy-2-naphthoic acid hydrazide. Among these, lauric acid hydrazide and salicylic acid hydrazide are particularly preferably used. The monohydrazide compounds may be used alone or in combination of two or more.

There is no particular limitation on the imidazole compound, and known compounds can be used. Specifically, for example, 2-methylimidazole, 2-ethylimidazole, 2-propylimidazole, 2,2-dimethylimidazole, 2
-Ethyl-4-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-undecylimidazole, 2-heptadecylimidazole and the like can be mentioned. The imidazole compounds may be used alone or in combination of two or more.

The acid anhydride is not particularly limited and known ones can be used. Specifically, for example, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride,
4-methylhexahydrophthalic anhydride, 4-methyltetrahydrophthalic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenonetetracarboxylic acid, succinic anhydride, methylsuccinic anhydride, dodecenylsuccinic anhydride, itaconic anhydride , Maleic anhydride, cyclopentane tetracarboxylic acid anhydride, methyl nadic acid anhydride, chlorendic acid anhydride, and the like. The acid anhydrides may be used alone or in combination of two or more.

As the tertiary amine compound, known compounds can be used without particular limitation, and examples thereof include diethylenetriamine, benzyldimethylamine, α-methylbenzyldimethylamine, tri-n-butylamine, 2,4,6-tris (dimethyl). Aminomethyl) phenol, triethanolamine, N, N'-dimethylpiperazine, 1,8-
Diazabicyclo (5,4,0) undecene-1 (DB
U), tetramethylguanidine, etc. can be mentioned. The tertiary amine compounds may be used alone or in combination of two or more.

The carboxylic acid includes known monocarboxylic acids and polycarboxylic acids. Examples of the monocarboxylic acid include lauric acid, salicylic acid, propionic acid, p-hydroxybenzoic acid, naphthoic acid and 3-hydroxy-2-naphthoic acid. Examples of the polycarboxylic acid include oxalic acid, malonic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, maleic acid, fumaric acid, diglycolic acid, tartaric acid, malic acid, isophthalic acid, terephthalic acid. Acid, hexahydrophthalic acid, dimer acid and the like can be mentioned. The carboxylic acids may be used alone or in combination of two or more.

The dicyandiamide compound is not particularly limited and known compounds can be used. Specific examples thereof include dicyandiamide, o-tolylbiguanide, phenyl biguanide, α-benzyl biguanide, α-2,5-dimethyl biguanide and phenyl. Examples thereof include biguanide oxalate. The dicyandiamide compound may be used alone or in combination of two or more.

Among these curing accelerators, monohydrazide compounds and imidazole compounds are preferable, and monohydrazide compounds are particularly preferable.

The amount of the above-mentioned curing accelerator used is not particularly limited and can be appropriately selected from a wide range depending on the application of the resin cured product to be obtained, but usually 0.01 to 50 per 100 parts by weight of the dihydrazide compound. Parts by weight, preferably 0.
It may be about 1 to 10 parts by weight, more preferably about 0.1 to 1 part by weight.

The aqueous resin composition of the present invention contains a rheology modifier, an anti-settling agent, an anti-color separation agent, a pigment, a pigment dispersant, a leveling agent, an anti-repellent agent, a defoaming agent, a delustering agent,
Known additives such as an antistatic agent, an anti-skinning agent, an antioxidant, an ultraviolet absorber, a coloring preventing agent, an antiseptic agent, an insect repellent, a fungicide and a bactericide may be contained.

The aqueous resin composition of the present invention can be produced by mixing the above-mentioned components and further adding an appropriate amount of water if necessary. In the composition of the present invention, each component may be mixed at the time of use, three components of an acrylic resin, an epoxy resin and a dihydrazide compound may be mixed with water and a curing accelerator may be added at the time of use, or an acrylic resin may be added. It is also possible to mix two components of a resin and an epoxy resin with water and add a dihydrazide compound and a curing accelerator at the time of use. The total solid content concentration in the composition of the present invention is not particularly limited and can be appropriately selected from a wide range depending on the application of the resin cured product to be obtained, but is usually about 0.01 to 10% by weight, preferably 0.0
It is preferable to set it to about 5 to 5% by weight.

The thus obtained aqueous resin composition of the present invention is of course cured at a temperature around 200 ° C., but it is usually cured at room temperature to about 120 ° C., preferably about 60 ° C. to 100 ° C.

Since the aqueous resin composition of the present invention has an extremely long pot life, it cures in a very short time of about a few minutes to a dozen minutes, so that it can be applied to a wide range of applications. Specifically, the aqueous resin composition of the present invention is a paint,
It can be suitably used as an adhesive, a lining material, a sealing material, a fiber processing agent and the like. Examples of the application method at this time include known methods such as brush coating, coating with a roll coater, blade coater, bar coater, dipping, spray coating, and the like. Further, for example, it can be formed into an arbitrary shape such as a film or a sheet, placed on a base material or sandwiched between base materials, and if necessary, pressure-bonded under heating. The base material to which the aqueous resin composition of the present invention can be applied is not particularly limited, and examples thereof include synthetic resin, metal, wood, and ceramics.

[0029]

The present invention will be specifically described below with reference to examples and comparative examples.

Example 1 Acetoacetylation degree of 6.0 mol%, Saponification degree of 99 mol%
10% by weight of acetoacetylated polyvinyl alcohol
1 part by weight of an epoxy resin (trade name: Epitote YD-128, manufactured by Toto Kasei Co., Ltd.) per 100 parts by weight of the aqueous solution,
5 parts by weight of a 10% by weight aqueous solution of adipic acid dihydrazide (curing agent) and 2 parts of salicylic acid hydrazide (curing accelerator)
When 1 part by weight of a wt% aqueous solution was added and the mixture was stirred and mixed at room temperature and the gel time was measured, it was 2 minutes.

After removing the resin cured product from the reaction mixture, the reaction solution was analyzed by redox titration and gas chromatography, and adipic acid dihydrazide was not detected.

Comparative Example 1 The same procedure as in Example 1 was carried out except that salicylic acid hydrazide was not used, but satisfactory curing did not occur.

Examples 2 to 7 Gel time was measured in the same manner as in Example 1 except that the curing accelerator shown in Table 1 was used instead of salicylic acid dihydrazide. The results are shown in Table 1.

[0034]

[Table 1]

In Examples 2 to 7, a cured resin product was taken out from the reaction mixture after completion of the curing reaction, and the remaining reaction solution was analyzed in the same manner as in Example 1. As a result, adipic acid hydrazide was not detected. .

Example 8 200 g of water was heated to 100 ° C., and an epoxy resin raw material (polyglycerol polyglycidyl ether) 2 was added thereto.
g, 5 g of adipic acid cishydrazide and 0.5 g of salicylic acid hydrazide, and immediately add 7 g of acrylic fiber (diameter 200 μm × length 20 m) to the solution,
It was immersed for 5 minutes at a temperature of ° C. Then, the acrylic fiber to be treated was taken out and dried at 130 ° C.

When the solution after taking out the fiber to be treated was analyzed in the same manner as in Example 1, adipic acid dihydrazide was not detected.

The fibers to be treated are immersed in 100 ml of water for 30 minutes, and then the fibers are removed by filtration.
When the remaining water was analyzed, adipic acid dihydrazide was not detected.

From the above results, it is considered that the acrylic resin and the adipic acid dividrazide are bonded via the epoxy resin.

Examples 9 to 14 The procedure of Example 8 was repeated except that the curing accelerator shown in Table 2 was used instead of salicylic acid hydrazide, and the curing reaction and the residual amount of adipic acid dihydrazide were analyzed. Table 2 shows the results.

[0041]

[Table 2]

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Kitajima 463 Kagasuno, Kawauchi Town, Tokushima City, Tokushima Prefecture Otsuka Chemical Co., Ltd., Tokushima Plant

Claims (3)

[Claims] 1. An aqueous resin emulsion as a main component,
(A) an epoxy resin as a modifier, (b) a dihydrazide compound as a curing agent, and (c) a monohydrazide compound, an imidazole compound, an acid anhydride as a curing accelerator,
An aqueous resin composition containing at least one selected from a tertiary amine compound, a carboxylic acid and a dicyandiamide compound. 2. The aqueous resin composition according to claim 1, wherein the aqueous resin emulsion is at least one selected from acrylic resins and polyvinyl alcohol. 3. The aqueous resin composition according to claim 1, wherein the curing accelerator is at least one selected from a monohydrazide compound and an imidazole compound.