JPH08188606A - Preparation of room-temperature-curing aqueous resin dispersion - Google Patents

Abstract

PURPOSE: To obtain a room-temperature-curing aqueous resin dispersion having a film Tg in a specified range, excellent water resistance and good contact by emulsion-polymerizing a radical-polymerizable monomer in the presence of an epoxy resin and an oil-soluble polymerization initiator in an aqueous medium. CONSTITUTION: A radical-polymerizable monomer is emulsion polymerized in an amount of 40-80 pts.wt. in the presence of 20-60 pts.wt. epoxy resin and an oil-soluble polymerization initiator in an aqueous medium to obtain a room- temperature-curing aqueous resin dispersion which can give a film of a Tg of 10 to -40 deg.C. As the radical initiator is used, this composition has good water resistance and good contact as compared with a conventional aqueous resin dispersion being a combination with an epoxy resin. Further, it can be smoothly cured with an epoxy resin into a highly heat-resistant product and has performance equivalent to that of a solvent-based chloroprene adhesive.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a room temperature curable aqueous resin dispersion which exhibits tackiness when dried at room temperature or by heating and which becomes non-tacky over time. Specifically, a room temperature curable water-based resin dispersion that gives high adhesive strength immediately after drying and can be left at room temperature as it is to obtain high heat resistance, water resistance, and adhesiveness is obtained. The present invention relates to a method for producing a resin dispersion.

[0002]

2. Description of the Related Art In recent years, resource-saving and global environment-friendly materials have been developed. Among them, solvent-based chloroprene adhesives are being actively replaced. This chloroprene adhesive has (1) adhesive strength immediately after solvent drying (contact property)
Is favorable, (2) high adhesiveness due to high crystallinity after curing, and (3) good heat resistance and water resistance. This chloroprene adhesive is made water-based by, for example, emulsifying chloroprene rubber and improving the performance of conventional thermoplastic acrylic emulsions and urethane emulsions. The balance between water resistance and water resistance cannot be achieved, and nothing is satisfactory yet.

On the other hand, it has been attempted to balance the contact property, the adhesive strength after curing, the heat resistance and the water resistance by combining not only the conventional thermoplastic emulsion alone but also a thermosetting epoxy resin.

[0004]

However, simply blending the emulsion of the epoxy resin may cause the epoxy resin and the remaining polymer component to separate during storage, or may be used when the epoxy resin emulsion is produced. There is a drawback that a large amount of emulsifier affects the water resistance. On the other hand, for example, JP-A-49-10658
No. 6 discloses an emulsion polymerization in the presence of an epoxy resin to solve the problem of separation. Also, JP-A-57-115418
In the report, the compatibility of the epoxy resin with the acrylic polymer was improved by partially making the end of the epoxy resin an acryloyl group, preventing separation during storage and improving the performance. Although the conventional problems have been considerably solved by these improvements, since a water-soluble compound is used as a polymerization initiator, it is a factor that impairs water resistance due to this. Therefore, it has been difficult to balance the currently required high contact properties with the adhesive strength after curing, heat resistance and water resistance.

[0005]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the emulsion polymerization of an epoxy resin and a radical-polymerizable monomer in an aqueous medium has been studied, and in particular, a polymerization initiator at that time has been studied and obtained. It was completed by paying attention to the Tg of the film of the aqueous resin dispersion. That is, in the present invention, in the presence of 20 to 60 parts by weight of (A) epoxy resin,
(B) 40 to 80 parts by weight of a radical-polymerizable monomer is emulsion-polymerized in an aqueous medium by using an oil-soluble polymerization initiator, and a Tg of a film obtained from an aqueous resin dispersion is 10 It is a method for producing a room temperature curable aqueous resin dispersion having a temperature of -40 ° C.

The present invention will be described in detail below. The epoxy resin used in the present invention is a compound having one or more epoxy groups in one molecule, for example, glycidyl ethers, glycidyl esters, glycidyl amines,
Examples include linear aliphatic epoxides and alicyclic epoxides.

Examples of the glycidyl ethers include aromatic glycidyl ethers and aliphatic glycidyl ethers. Examples of the aromatic glycidyl ethers include bisphenol diglycidyl ether, phenol novolac polyglycidyl ether, and biphenol diglycidyl ether. . Examples of the diglycidyl ether of bisphenol include diglycidyl ethers such as bisphenol A, bisphenol F, bisphenol AD, bisphenol S, tetramethylbisphenol A, and tetrabromobisphenol A,
Examples of the polyglycidyl ether of phenol novolac include polyglycidyl ethers such as phenol novolac, cresol novolac, and brominated phenol novolac, and examples of the diglycidyl ether of biphenol include diglycidyl ether of biphenol and tetramethyl biphenol. Examples of the aliphatic glycidyl ether include glycidyl ethers such as polyethylene glycol, polypropylene glycol, glycerin and tetramethylene glycol. Examples of glycidyl esters include aromatic glycidyl esters and alicyclic glycidyl esters. Examples of the aromatic glycidyl ester include diglycidyl ester such as phthalic acid, terephthalic acid and isophthalic acid, and examples of the alicyclic glycidyl ester include hexahydrophthalic acid, tetrahydrophthalic acid,
Examples include glycidyl esters such as dimer acid.

Examples of the glycidyl amines include tetraglycidyl diaminodiphenylmethane, tetraglycidyl metaxylylenediamine, triglycidyl aminofer and the like. Examples of the linear aliphatic epoxides include epoxidized polybutadiene and epoxidized soybean oil, and examples of the alicyclic epoxides include 3,4 epoxy-6-methylcyclohexylmethylcarboxylate and 3,4 epoxycyclohexylmethylcarboxylate. Rate etc. are mentioned.

The epoxy resins may be used alone or in combination of two or more kinds. From the viewpoint of heat resistance and water resistance, preferred epoxy resins are glycidyl ethers, more preferably bisphenol diglycidyl ethers, and particularly preferably biphenol A and biphenol F diglycidyl ethers. The epoxy equivalent of the epoxy resin may be in the range of 100 to 10000, and is preferably 150 to 3000, more preferably 170 to 1000 from the viewpoint of room temperature curability, heat resistance and water resistance.

Examples of the radically polymerizable monomer used in the present invention include a. An aromatic unsaturated compound, b. α, β-
Unsaturated monocarboxylic acid alkyl ester, c. α, β-
Combinations of unsaturated monocarboxylic acids and the like can be mentioned.
Examples of the aromatic unsaturated compound include styrene, α-methylstyrene, vinyltoluene and the like. α, β
Examples of the unsaturated monocarboxylic acid alkyl ester include C1 to C12 alkyl esters of acrylic acid or methacrylic acid. Examples of the C1-C12 alkyl ester of acrylic acid or methacrylic acid include methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, isobutyl acrylate, hexyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, methyl methacrylate, Examples thereof include ethyl methacrylate, propyl methacrylate, isopropyl acrylate, butyl methacrylate, isobutyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate and lauryl methacrylate. Examples of the α, β-unsaturated monocarboxylic acid include acrylic acid and methacrylic acid.

The radical polymerizable monomer is preferably
a. An aromatic unsaturated compound, b. C1-C12 alkyl esters of α, β-unsaturated monocarboxylic acids, c. α, β
A combination of unsaturated monocarboxylic acids, a, b,
c may be used alone, or each may be a mixture of two or more kinds. Preferably a. The aromatic unsaturated compound is styrene, b. The C1 to C12 alkyl ester of α, β-unsaturated monocarboxylic acid is ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, more preferably butyl acrylate, and α, β-unsaturated monocarboxylic acid is Methacrylic acid.

If desired, other radical polymerizable monomers other than the above may be combined. For example, a hydroxyl group-containing monomer such as 2-hydroxyacrylate, 2
-Hydroxymethacrylate, polyethylene glycol acrylate, amide group-containing monomer such as acrylamide, methacrylamide, methylol group-containing monomer such as N-methylolacrylamide, dimethylolacrylamide, alkoxymethyl group-containing monomer such as N
-Butoxymethyl acrylamide, N-methoxymethyl acrylamide, epoxy group-containing monomers such as glycidyl acrylate, glycidyl methacrylate, α, β
Mono- or diesters of ethylenically unsaturated dicarboxylic acids such as mono- or dibutyl maleate, mono- or dioctyl fumarates, vinyl esters such as vinyl acetate,
Vinyl propionate, unsaturated nitriles such as acrylonitrile, methacrylonitrile, unsaturated carboxylic acids such as maleic acid, fumaric acid, itaconic acid, olefins such as butadiene, isoprene, chlorine-containing vinyl monomers such as vinyl chloride, vinylidene chloride, chloroprene, divinyl monomers such as Examples thereof include divinylbenzene, polyoxyethylene diacrylate, polyoxyethylene dimethacrylate and the like.

In the present invention, the ratio of the epoxy resin to the radically polymerizable monomer is 40 to 80 parts by weight of the radically polymerizable monomer with respect to 20 to 60 parts by weight of the epoxy resin. If the amount of the epoxy resin is less than 20 parts by weight, the heat resistance and water resistance will be poor, and if it exceeds 60 parts by weight, the contact property will be poor. Epoxy resin is preferably 25-5
The radical polymerizable monomer is 45 to 75 parts with respect to 5 parts by weight.
Parts by weight.

The Tg of the film obtained from the aqueous resin dispersion of the present invention is 10 to -40 ° C. If it exceeds 10 ° C, the contact property becomes insufficient and the adhesive strength becomes poor, and if it is less than -40 ° C, the adhesive strength becomes insufficient. It is preferably 0 to -30 ° C. The film obtained from the present invention preferably has a state in which the vinyl polymer and the uncured epoxy resin are compatible with each other. That is, the compatibility causes the Tg of the film to depend not only on the factor of the vinyl polymer but also on the amount and molecular weight of the dissolved epoxy resin. For example, even if the Tg of the vinyl polymer itself is set to be high, the Tg of the film decreases due to the plasticizing effect when the amount of the epoxy resin added is large. The reverse is also possible. Therefore, the composition ratio of the radically polymerizable monomer is also set from the Tg of the film under the compatibility with the epoxy resin. However, the optimum range of the composition ratio of the radical-polymerizable monomer is appropriately determined in terms of contact properties, heat resistance after curing of the epoxy resin, and water resistance.

The preferred radically polymerizable monomers of the present invention are a. An aromatic unsaturated compound, b. a C1-C12 alkyl ester of an α, β-unsaturated monocarboxylic acid, and c. The composition ratio of acrylic acid and / or methacrylic acid is preferably a. 20-80% by weight of aromatic unsaturated compound, b. C1 to C1 of α, β-unsaturated monocarboxylic acid
20-80% by weight of alkyl ester of 2, c. 0.1 to 20% by weight of acrylic acid and / or methacrylic acid
Is.

The Tg of the present invention uses a differential scanning calorimeter,
It can be measured from 100 ° C. at a heating rate of 10 ° C./min. The inflection point of the obtained data is Tg, and when there are two or more inflection points, the inflection point on the high temperature side is Tg. When measuring Tg, the sample must be an aqueous resin dispersion dried at room temperature or by heating. However, in the case of drying by heating, excessive heating is accompanied by a change in Tg, so it is necessary to perform it as quickly as possible.

Polymerization in the aqueous medium in the present invention is carried out by a conventionally known emulsion polymerization technique. That is, it is carried out in the presence of a radical polymerizable monomer, a radical polymerization initiator, water, and a surfactant, and is characterized in that an oil-soluble radical polymerization initiator is used as the radical polymerization initiator. For example, an oil-soluble radical polymerization initiator is dissolved in a radical-polymerizable monomer in advance by stirring sufficiently at room temperature or under heating to uniformly dissolve the radical-polymerizable monomer, and an epoxy resin is added thereto to be dissolved uniformly. In this method, a surfactant, a dispersant, a protective colloid, and the like are added to water to prepare an emulsion dispersion, which is then polymerized. In addition to this method, for example, a method of separately emulsifying and dispersing a radical polymerizable monomer in which an epoxy resin and an oil-soluble radical polymerization initiator are dissolved, and subjecting it to polymerization, and emulsifying and dispersing only an epoxy resin to initiate an oil-soluble radical polymerization Examples include a method of directly polymerizing a radically polymerizable monomer in which the agent is dissolved. The radical polymerizable monomer and the epoxy resin may or may not react during the emulsion polymerization. It is better not to react.

The surfactant used is ionic,
There are nonionic surfactants, and examples of the ionic surfactant include anionic, cationic and amphoteric surfactants. Examples of the anionic surfactant include fatty acids, sulfuric acid ester salts of higher alcohols, sulfuric acid ester salts of liquid fatty oils, sulfuric acid salts of aliphatic amines and aliphatic amides, phosphoric acid esters of aliphatic alcohols, dibasic fatty acid esters. Examples of the cationic surfactants include primary amine salts, secondary amine salts, tertiary amine salts, and aliphatic amide sulfonates, alkylaryl sulfonates, formalin-condensed naphthalene sulfonates, and the like. Amine salt,
Examples thereof include quaternary ammonium salts and pyridinium salts. Examples of the amphoteric surfactants include carboxylate type, sulfate ester type, sulfonate type and phosphate ester salts. Examples of the nonionic surfactant include polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene alkyl ester, sorbitan alkyl ester, polyoxyethylene sorbitan alkyl ester and the like. In addition to the non-reactive surfactants listed above, reactive surfactants can also be used. The reactive surfactant has a radically polymerizable functional group in one molecule and has a sulfonic acid group, a sulfonate ester group, a sulfonate group,
Those having one or more functional groups selected from sulfonic acid ester bases, or polyoxyethylene, polyoxypropylene, polyoxyethylene polyoxypropylene composite type alkyl ether having a radically polymerizable functional group in one molecule Alternatively, it has alcohol. These surfactants may be used alone or in combination with two or more kinds. Examples of the dispersant and protective colloid include polyphosphate, polyacrylate, maleic anhydride copolymer salt, polyvinyl alcohol, hydroxyethyl alcohol and the like.

An oil-soluble polymerization initiator is used as the polymerization initiator. The oil-soluble polymerization initiator referred to here is 100 g.
Initiator having a solubility of 0.1 g or less in water. Examples of oil-soluble polymerization initiators include peroxides and oil-soluble azobis compounds, examples of peroxides include benzoyl peroxide and lauroyl peroxide, and examples of oil-soluble azobis compounds include 2 , 2 '
-Azobisisobutyronitrile, 2,2'-azobis-
2-methylbutyronitrile, 2,2'-azobis-2,
4-dimethylvaleronitrile and the like can be mentioned.

In the polymerization of the present invention, if necessary, a pH adjusting agent such as sodium hydrogen phosphate or sodium hydrogen carbonate, a molecular weight adjusting agent such as t-dodecyl mercaptan, n-dodecyl mercaptan or a low molecular weight halogen compound, a plasticizer, an organic compound. A solvent or the like can be added before, during or after the emulsion polymerization. The polymerization temperature is, for example, 0 to 100 ° C., particularly preferably 30 to 90 ° C., and the polymerization is carried out in an inert atmosphere under normal pressure or, if necessary, under pressure.

The aqueous resin dispersion of the present invention may be used as it is, but a curing agent may be added as necessary to cure the epoxy resin contained therein. Examples of the curing agent include polyamine-based, acid anhydride-based, phenolic resin, polymercaptan, and Lewis acid complex.
Examples of the polyamine-based curing agent include aliphatic polyamines, alicyclic polyamines, aromatic polyamines, polyamides and tertiary amines. Examples of the aliphatic polyamines include ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine and these. And modified products thereof. Examples of the alicyclic polyamine include:
Examples thereof include isophoronediamine, menthanediamine, N-aminoethylpiperazine, diaminodicyclohexylmethane and modified products thereof. Examples of aromatic polyamines include m-xylylenediamine, diaminodiphenylmethane, m-phenylenediamine, diaminodiphenylsulfone, and modified products thereof. Examples of the polyamide include a condensation product of a dicarboxylic acid such as dimer acid and the above polyamine. Examples of tertiary amines include tertiary amino group-containing compounds such as dimethylbenzylamine, 2,4,6-trisdimethylaminomethylphenol and modified products thereof, imidazole, 2-methylimidazole, 2-ethyl- Examples thereof include imidazole compounds such as 4-methylimidazole and 2-phenylimidazole and modified products thereof. Other polyamines include dicyandiimide and adipic acid dihydrazide. As the acid anhydride, for example, monofunctional phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride,
Examples thereof include methylhexahydrophthalic anhydride and modified products thereof, and bifunctional compounds include pyromellitic anhydride, benzophenonetetracarboxylic acid anhydride, and modified products thereof. Examples of the phenol resin include novolac type phenol resin and resol type phenol resin, and examples of the polymercaptan include condensate of thioglycolic acid and polyhydric alcohol and polysulfide. Examples of the Lewis acid complex include an amine complex of boron trifluoride. These curing agents may be used alone or in combination of two or more. A polyamine-based curing agent is preferable. The addition amount of the polyamine-based curing agent is preferably equivalent to the epoxy group contained. When the water-based resin dispersion of the present invention is used, the contact property is not impaired even with a polyamine-based curing agent with a large blending amount.

When the aqueous resin dispersion of the present invention is cured with a curing agent, for example when it is applied as an adhesive, both may be mixed before being applied to the adherend, or one of the adherends may be mixed. A method in which the aqueous resin dispersion of the present invention is applied, the curing agent is applied to the other adherend, and the coated surfaces of both adherends are overlapped and mixed can also be used. In particular, the latter method has an advantage that the working time can be extended.

The aqueous resin dispersion obtained according to the present invention may be cured at room temperature or after heating to vaporize water and then at room temperature, or may be cured by heating.
In addition, the adherends may be stuck together without volatilizing water, and curing may proceed at room temperature or heating. If necessary, a tackifier and a rubber component may be added to the aqueous resin dispersion obtained by the present invention. Examples of the tackifier include natural tackifiers such as rosin, rosin derivative, terpene resin, and terpene derivative, petroleum resin, styrene resin, coumarone indene resin, phenol resin, xylene resin, etc. Examples of synthetic tackifiers include: These tackifiers are preferably added in the form of an aqueous dispersion or an aqueous solution. Examples of the rubber component include liquid nitrile rubber and silicone rubber. Further, an amino resin such as a melamine resin, a urea resin or a benzoguanamine resin may be added to further improve the curing performance. Also, bactericides, preservatives,
You may add a defoaming agent, a plasticizer, a pH adjuster, etc.

The aqueous resin dispersion obtained by the present invention is
It can be used not only for adhesives and pressure-sensitive adhesives, but also for paints, printing inks, gas barrier packaging materials, processed papers, fiber processing agents, building materials and the like. As the adhesive, for example, wood,
Plywood, particle board, gypsum board, metal such as iron and aluminum, plastic film, plastic foam, non-woven fabric of plastics, cloth such as leather, cotton, linen, etc., glass fiber, glass cloth, and adhesion of FRP can be mentioned. Examples of the adhesive field include tapes, labels, wallpaper, flooring materials, etc., and examples of the coating field include concrete, wood, metals, floor polishes, etc., and examples of fiber processing agents include non-woven fabrics, carpets, electric flocking cloths. , Laminated fabrics, tire cords, and the like, and building materials include, for example, sealing materials, latex cement, waterproof materials, and the like.

[0025]

Embodiments of the present invention will be described below. Parts are based on weight unless otherwise specified.

[0026]

Examples 1 to 12 and Comparative Examples 1 to 5 (1) Preparation of emulsion (Preparation of emulsion of Examples 1 to 12) Table 1 is shown in 100 parts of the mixture of the radical-polymerizable monomer and the epoxy resin shown in Table 1. After dissolving the oil-soluble radical initiator, 8 parts of a 25% aqueous solution of Emulgen 950 (polyoxyethylene nonylphenyl ether manufactured by Kao Corporation) and Lebenol WZ (sodium polyoxyethylene nonylphenyl ether sulfate manufactured by Kao Corporation) were added. A 25% aqueous solution (4 parts) and distilled water (43 parts) were added, and the mixture was stirred with a homomixer to prepare a pre-emulsion. Separately, add distilled water 40 to a flask equipped with a stirrer.
Part, 2 parts of 25% aqueous solution of Emulgen 950 were charged, and 8
Heat to 0 ° C. The pre-emulsion was continuously added dropwise thereto over 4 hours, and polymerization was continued at the same temperature for 3 hours. Then 3
Cool down to below 0 ℃ and adjust the pH with 25% aqueous ammonia.
Was adjusted to 7 to obtain an emulsion having a solid content of 50%. Table 1 also shows the viscosity after the polymerization and the Tg after the emulsion was dried.

(Preparation of Emulsions of Comparative Examples 1 to 5) Emulsion polymerization was performed on the mixture of the radically polymerizable monomer and epoxy resin shown in Table 2 by the same method as in Examples to obtain emulsions. The viscosity after polymerization and the Tg after drying the emulsion are also shown in Table 2. However, in Comparative Example 5, 0.2 part of water-soluble APS was used as a radical initiator. (2) Evaluation method and evaluation result a. Blending with curing agent The emulsions obtained in Examples 1 to 12 and Comparative Examples 1 to 5 were mixed with the commercially available curing agent Ancamine 2075 (manufactured by ACI Japan Limited, modified alicyclic polyamine, added amount of epoxy resin). 40 phr), Ancamine 1769
(ACI Japan Limited, modified aliphatic polyamine, addition amount: 25 phr relative to epoxy resin), 2
-Methylimidazole (addition amount 5 for epoxy resin)
(phr) was mixed with stirring at the ratios shown in Tables 3 and 4 to obtain a blended product.

B. Evaluation of Adhesive Performance The above compounded products were evaluated for adhesive performance by the method shown below. The results are shown in Tables 5-6. Coating / Adhesion After adjusting the viscosity of the blended product to 5000 cps with a thickener,
Plywood and 1 inch wide 9 using wire bar # 75
It is applied to No. canvas and dried at 20 ° C. for 20 minutes. Then, the dried surfaces of the blended products were stuck together, and a 4.5 kg roller was reciprocated twice.

Initial Adhesion Strength After bonding, a sample left at 20 ° C. for 1 hour was used to measure 180 ° peel strength with a Tensilon tensile tester. A weight of 2.0 kg / inch or more is judged to be acceptable. The pulling speed was 50 mm / min. Adhesive strength after curing Using a sample that was left for 7 days at 20 ° C after bonding,
180 ° peel strength was measured with a Tensilon tensile tester. It is judged to be acceptable when it is 4.0 kg / inch or more. The pulling speed was 50 mm / min.

Heat resistance The sample which was left at 20 ° C. for 7 days after being laminated was
In a ℃ atmosphere, pull a 400g weight in the 90 ° direction,
If the weight did not drop after standing for 24 hours, it was judged as pass, and if it dropped, it was judged as fail. The weight was attached to the canvas side. A sample that had been water-resistant laminated and left at 20 ° C. for 7 days was immersed in distilled water for 7 days, and then the 180 ° peel strength was immediately measured by a Tensilon tensile tester. 2.0 kg /
Inch or higher is judged to pass. Pulling speed is 50m
It was set to m / min.

[0031]

[Table 1]

[0032]

[Table 2]

[0033]

[Table 3]

[0034]

[Table 4]

[0035]

[Table 5]

[0036]

[Table 6]

[0037]

The aqueous resin dispersion obtained from the present invention is
Since the oil-soluble radical initiator is used as compared with the conventional water-based resin dispersion in combination with the epoxy resin, the water resistance is good and the contact property is also good. Further, since the curing with the epoxy resin proceeds smoothly, it has a high degree of heat resistance and has the same performance as that of the solvent-based chloroprene adhesive.

Claims (1)

[Claims] 1. Emulsion polymerization of 40 to 80 parts by weight of a radically polymerizable monomer (B) in the presence of 20 to 60 parts by weight of an epoxy resin (A) in an aqueous medium using a polymerization initiator that is oil-soluble. A process for producing a room temperature curable aqueous resin dispersion, wherein the Tg of the film obtained from the aqueous resin dispersion is 10 to -40 ° C.