JPH0256366B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing an aqueous dispersion that has excellent adhesion and water resistance, and has a low solvent content. In recent years, aqueous polymer dispersions obtained by emulsion polymerization, such as acrylic, acrylic-styrene, vinyl acetate, and ethylene-vinyl acetate, have been used in paints,
It has come to be widely used in industrial applications such as adhesives. However, the films formed from these conventional aqueous polymer dispersions have insufficient adhesion to metals, wood, cured cement, plastics, etc., and often peel or blister, especially in wet conditions or at high temperatures. It had serious defects. In order to improve these defects, efforts have been made to reduce the amount of water-sensitive substances such as surfactants and protective colloids contained in the aqueous polymer dispersion, and to create crosslinked structures by introducing functional groups into the polymer skeleton. Although attempts have been made to form In order to improve these drawbacks, it is possible to improve the water resistance of the coating film of an aqueous dispersion by blending a thermosetting resin, such as an epoxy resin, with a carboxyl group-containing acrylic polymer to impart a self-emulsifying function. It is being done. However, blends of epoxy resins and carboxyl group-containing acrylic polymers are usually obtained by solution polymerization of epoxy resins and acrylic monomers. Therefore, the solvent from solution polymerization always remains in this aqueous dispersion, causing problems such as poor stability of the aqueous dispersion and odor generated during baking, so it is necessary to reduce the amount of solvent used. ing. Reducing the amount of solvent contained in this aqueous dispersion also
There are solutions such as increasing the solid content during solution polymerization or removing the solvent from the aqueous dispersion under reduced pressure, but increasing the solid content during solution polymerization may make the solution polymerized product more likely to gel or The method of removing the solvent from an aqueous dispersion under reduced pressure also has problems such as difficulty in removing high-boiling point solvents, which has not yet been satisfactorily solved. Therefore, a method for producing an aqueous dispersion necessary for forming a coating film with excellent water resistance, solvent resistance, and physical properties has been desired, which fundamentally improves the deficiencies of the prior art. Based on these facts, the present invention has good storage stability, allows easy control of the amount of solvent in the aqueous dispersion, and can remove residual acrylic monomers remaining during solution polymerization, resulting in a coating film The present invention was developed as a result of intensive studies to find an aqueous dispersion that has uniform and good water resistance, heat resistance, and adhesive properties. That is, the present invention provides a bisphenol compound having one or more epoxy groups in one molecule and two or more ethylenic monomers containing acrylic acid or methacrylic acid as an essential component. This relates to a method for producing an aqueous dispersion by ultrafiltrating an aqueous dispersion obtained by performing solution polymerization, then neutralizing it by adding a basic compound, and adding water. . The present invention will be explained in more detail below. A typical example of the bisphenol compound having one or more epoxy groups in one molecule used in the present invention is a condensate of epichlorohydrin and a bisphenol compound. In this case, the bisphenol compound includes, for example, 2,
2'-bis(4,4'-hydroxyphenyl)propane (commonly known as bisphenol A), halogenated bisphenol A, bis(4,4'-hydroxyphenyl)methane (commonly known as bisphenol F), bis(4,4'-hydroxyphenyl)propane (commonly known as bisphenol F), ，
4'-hydroxyphenyl) sulfone (commonly known as bisphenol S) can be mentioned. Preferred are bisphenol A type glycidyl ether epoxy compounds. Also, used in the present invention
Bisphenol compounds in which the epoxy of the bisphenol compound (b) is replaced with an average of 0.1 to 1.5 acryloyl or methacryloyl groups per molecule include aromatic epoxy compounds, acrylic acid or methacrylic Mention may be made of epoxy acrylates or epoxy methacrylates obtained by reaction with acids. The epoxy equivalent of the bisphenol compound having an epoxy group is not particularly limited, and is 100
~10000 can be used. As the ethylenic monomer used in the present invention, acrylic acid or methacrylic acid is used as an essential component, and in addition, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, etc. Acrylic acid alkyl esters, methacrylic acid alkyl esters corresponding to the above alkyl esters, aromatic vinyl compounds such as styrene, α-methylstyrene, vinyltoluene, mono- or butyl maleate, mono- or dioctyl fumarate, etc. Mono- or diesters of α,β-ethylenically unsaturated dicarboxylic acids, vinyl esters such as vinyl acetate and vinyl propionate, vinyl ethers, unsaturated nitrile acids such as acrylonitrile and methacrylonitrile, ethylene, butadiene, isoprene, etc. Examples include olefins, vinyl chloride, vinylidene chloride, chlorine-containing vinyl compounds such as chloroprene, and the like. If desired, 2-hydroxyethyl acrylate, 2-methacrylic acid, etc., mainly based on the above ethylenic monomer,
Hydroxyl group-containing monomers such as hydroxyethyl and polyethylene glycol monomethacrylate, amide group-containing monomers such as acrylamide and methacrylamide, methylol group-containing monomers such as N-methylolacrylamide and dimethylolacrylamide, N- Alkoxymethyl group-containing monomers such as butoxymethyl acrylamide, epoxy group-containing monomers such as glycidyl acrylate and glycidyl methacrylate, divinyl monomers such as divinylbenzene, polyoxyethylene diacrylate, and polyoxyethylene dimethacrylate. Functional or crosslinking monomers such as monomers can be combined. Preferably, the essential component acrylic acid or methacrylic acid is contained in an amount of at least 1 to 60% by weight in the total ethylenic monomer. This acrylic acid or methacrylic acid can be imparted with water dispersibility by the carbanion obtained by neutralization, and
It provides a carboxyl group for use in a crosslinking reaction with an epoxy group. In the case of solution polymerization in the present invention, the organic solvent that can be used is not particularly limited, but hydrophilic organic solvents are preferred, such as methanol,
By adding alkyl alcohols such as ethanol, propanol, and butanol, ether alcohols such as methyl cellosolve, ethyl cellosolve, propyl cellosolve, butyl cellosolve, methyl carbitol, and ethyl carbitol, and ether esters such as methyl cellosolve acetate and ethyl cellosolve acetate. Just do it. As the polymerization initiator, for example, peroxides, persulfates, azobis compounds, and redox systems in which these are combined with reducing agents can be used. The polymerization conditions are to maintain the polymerization temperature in the range of 60 to 120°C. If it is lower than 60°C, the polymerization time is too long, and if it is higher than 120°C, there is a risk of gelation during polymerization, making production difficult. In the present invention, the method for dispersing solution polymerized products in water is to add a basic compound to neutralize the carboxyl groups in the polymer partially or completely, mix uniformly, and then drop a specified amount of water. Just go. The basic compounds used in the present invention include the following. Monomethylamine, monoethylamine, dimethylamine, diethylamine, trimethylamine,
Examples include amines such as triethylamine, monomethanolamine, dimethanolamine, trimethanolamine, and dimethylaminoethanol, and inorganic basic compounds such as caustic soda and caustic potassium. In the present invention, the ratio of the bisphenol compound having an epoxy group to the ethylenic monomer can be arbitrarily selected, but preferably the bisphenol compound having an epoxy group is 10 to 90%
The ratio of the ethylenic monomer to the weight part is 90 to 10 parts by weight. The ultrafiltration treatment used in the present invention means that the pore size is
An aqueous dispersion is passed under pressure through one side of a microporous membrane having a diameter of 0.001 to several microns, and the resin in the aqueous dispersion is separated from low-molecular substances such as solvents, water, and residual monomers. In the present invention, the aqueous dispersion can be treated using a commonly used ultrafiltration device. This treatment allows the amount of solvent present in the aqueous dispersion to be controlled. By the way, when ultrafiltration treatment is performed as described above, low molecular weight substances permeate through the microporous membrane.
The water in the aqueous dispersion is reduced. Therefore, when performing ultrafiltration treatment, water is added to the aqueous dispersion as appropriate.
It is necessary to prevent the resin concentration from becoming too high. Preferably, the solid content concentration is 5 to 50%.
If it is less than 5%, the ultrafiltration treatment will take too long, and if it is more than 50%, the viscosity of the aqueous dispersion will be too high.
This is because there is no ultrafiltration. In the present invention, the solvent removal rate after ultrafiltration treatment of the aqueous dispersion obtained by adding a basic compound to neutralize after solution polymerization and adding water is not particularly limited. , preferably 5 to 95%. This effect of reducing the amount of solvent in the aqueous dispersion not only solves the problem of discharged solvent, but also contributes to improving the stability of the aqueous dispersion and the water resistance of the coating film. In the present invention, the aqueous dispersion after ultrafiltration treatment includes extenders, reinforcing agents, fillers, and pigments such as coal tar, glass fiber, asbestos fiber, boron fiber, carbon fiber, cellulose, and polyethylene. powder, polypropylene powder, quartz powder, mineral silicates such as mica, asbestos powder and slate powder, kaolin, aluminum oxide trihydrate,
aluminum hydroxide, chiyolk powder, gypsum, calcium carbonate, antimony trioxide, pentone, silica aerosol, lithon, barite, titanium dioxide, carbon black, graphite, oxide color pigments such as iron oxide, or metal powders such as aluminum powder or iron powder, and any of these can be used effectively depending on the purpose. In the present invention, the aqueous dispersion after ultrafiltration treatment is a coating composition for water-based emulsion paints such as clear paints for metals such as cans, colored paints combined with pigments, wall spray materials, and floor materials. It can be used in products or printing ink compositions. The present invention will be specifically explained below using Examples. In the examples, parts and % indicate parts by weight and % by weight. Example 1 A polymerizable monomer mixed solution is prepared as follows. Styrene 40 parts Methacrylic acid 25 2-Hydroxyethyl acrylate 20 Methyl methacrylate 10 Azobis-isobutyronitrile 0.5 Total 95.5 parts Add to this solution bisphenol A type epoxy resin AER-664 (trade name: Asahi Kasei Corporation), which has an epoxy equivalent of 950. Co., Ltd.) and 140 parts of n-butanol were added and mixed uniformly. Pour 50 parts of the mixed solution into a reactor and raise the temperature to 90°C. Add remaining mixture to approx.
Control the dripping temperature at 80-100℃ over a period of time,
After continuing the reaction for about 5 hours, a viscous solution is obtained.
After adding 5 parts of dimethylaminoethanol to this solution and mixing uniformly, 625.3 parts of demineralized water is added dropwise over about 1 hour. The obtained aqueous dispersion was treated with ultrafiltration laboratory module KCL1010 (trade name; manufactured by Asahi Kasei Industries, Ltd.). The results are shown in Table-1.

[Table] Reference example 1 Synthesis of epoxy compound having methacryloyl group Bisphenol A type epoxy resin AER-667 with epoxy equivalent of 2000 (product name: Asahi Kasei Corporation)
Dissolve 200 parts of ethyl cellosolve in 120 parts of ethyl cellosolve.
Add 0.02 part of NaOH with a small amount of water and raise the temperature to 120℃. Add 1.72 parts of methacrylic acid to this for about 2 hours, maintain the temperature at 120-130℃, and increase the acid value.
The reaction is terminated when the value becomes 0.5 or less. Although the obtained compound is a mixture, it has on average 1.6 epoxy groups and 0.4 methacryloyl groups in one molecule. Example 2 A polymerizable monomer mixture is prepared as follows. Styrene 40 parts 2-hydroxyacrylate 15 n-butyl acrylate 30 acrylic acid 25 lauroyl peroxide 2 Total 112 parts Add 140 parts of the compound synthesized in Reference Example 1 to the polymerizable monomer solution shown above, and n- Add 100 parts of butanol and mix evenly. Pour 50 parts of the mixed solution into a reactor and raise the temperature to 90°C. The remaining mixture is added dropwise over about 2 hours, the temperature is adjusted to 80-100°C, and the reaction is continued for about 5 hours to obtain a viscous solution. Add dimethylaminoethanol to this solution.
After adding 7.5 parts and mixing uniformly, demineralized water was added over about 1 hour to reach a solid content of 25%. The resulting aqueous dispersion was passed through an ultrafiltration laboratory module.
It was treated with ACL1010 (trade name; manufactured by Asahi Kasei Industries, Ltd.). The results are shown in Table-2.

[Table] Example 3 A polymerizable monomer mixed solution is prepared as follows. Styrene 30 parts Methyl methacrylate 30 Methacrylic acid 35 Azobis-isobutyronitrile 1 Total 96 Add to this solution 100 parts of bisphenol A epoxy resin AER-331 (trade name; manufactured by Asahi Kasei Corporation), which has an epoxy equivalent of 190. Add 100 parts of methyl ethyl ketone and mix evenly. Pour 50 parts of the mixed solution into a reactor and raise the temperature to 80°C. The remaining mixture was added dropwise over about 2 hours, the temperature was controlled at 80°C, and the reaction was continued for about 5 hours to obtain a viscous solution. After adding 10 parts of diethylaminoethanol to this solution and mixing uniformly, demineralized water was added over about 1 hour to reach a solid content of 40%. The resulting aqueous dispersion was passed through an ultrafiltration laboratory module.
Treated with KCL1010. The results are shown in Table-3.

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Claims (1)

[Scope of Claims] 1. (a) A bisphenol compound having one or more epoxy groups in the molecule and (b) Two or more ethylenic monomers having acrylic acid or methacrylic acid as an essential component, homogeneously mixed together. The aqueous dispersion obtained by mixing with the water, performing solution polymerization, then neutralizing by adding a basic compound, and adding water is subjected to ultrafiltration treatment to obtain an aqueous dispersion. A method for producing a characteristic aqueous dispersion. 2. Claim 1, characterized in that the epoxy group of the bisphenol compound of (a) is a bisphenol compound in which the epoxy group is replaced with an average of 0.1 to 1.5 acryloyl groups or methacryloyl groups per molecule. Manufacturing method described in section. 3 After solution polymerization, add a basic compound to neutralize,
2. The production method according to claim 1, wherein the aqueous dispersion obtained by adding water is subjected to ultrafiltration treatment so that the solvent removal rate is 5 to 95%.