JPH06279707A - Water-base undercoating agent for inorganic porous base material - Google Patents

Abstract

PURPOSE:To obtain the undercoating agent which is excellent in water resistance, hot water resistance, adhesion to a base material and resistance to freezing damage and can provide a coating film which does not cause unevenness in top coating. CONSTITUTION:The undercoating agent contains in an aqueous medium colloidal silica and a copolymer resin obtained by copolymerizing a monomer mixture comprising 2-20wt.% ethylenically unsaturated carboxylic acid and 80-98wt.% other monomer, wherein at least 5wt.% of the copolymer resin is solubilized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous undercoating agent for an inorganic porous substrate having a water-absorbing fine porous surface, which can be used for a wide range of substrates, and particularly water resistance, warm water resistance and frost damage resistance. And an aqueous undercoating agent for an inorganic porous substrate having excellent substrate adhesion.

[0002]

2. Description of the Related Art Hitherto, as a resin used for an undercoating agent for an inorganic porous substrate, a relatively low molecular weight moisture-curable urethane, a solvent type resin, etc. have been used. However, in both cases, there is a problem of fire hazard and environmental pollution due to the use of organic solvent, and there is a strong demand for water-based one. As the water-based undercoating agent, various ones having a water-soluble resin or an aqueous resin dispersion as a main component have been studied, but those having a water-soluble resin as a main component have poor water resistance,
In addition, the aqueous resin dispersion liquid is inferior in fluidity because the polymer is present in the form of particles and has a high molecular weight of generally 500,000 to 1,000,000, and as a result, the permeability to the base material, etc. There are drawbacks such as insufficient material adhesion and the inability to obtain a smooth coating film. In order to improve these drawbacks, so-called microemulsion with a small particle size, addition of water-soluble resin, etc. Being tried. However, in order to reduce the particle size of the polymer, a large amount of an emulsifier must be used, and if a large amount of an emulsifier is used, the water resistance of the film will be reduced due to the effect of the emulsifier, which is not preferred and Although the addition of the water-soluble resin improves the adhesion to the substrate, it cannot be denied that the water resistance of the film is lowered.

There is also a method of using an aqueous dispersion of an epoxy resin, but this method has excellent adhesion to a substrate, but since it uses a curing agent, it becomes a two-part solution, which is complicated to handle and has a long pot life. There are many problems in practice due to problems and restrictions on the time for overcoating. On the other hand, the base material that is the object to be coated is also diversifying more and more, and high density porous base materials, extruded plates, etc., which have been special in the past, have come to be used in a wide range. There is a demand for a water-based undercoating agent that can be used for various base materials, is easy to handle, and is excellent in water resistance, warm water resistance, frost damage resistance, substrate adhesion, and the like.

[0004]

DISCLOSURE OF THE INVENTION The present invention can be applied to a wide range of substrates, and is an inorganic porous group capable of giving a film excellent in water resistance, adhesion to the substrate, hot water resistance and frost damage resistance. The present invention is intended to provide a water-based undercoating material.

[0005]

As a result of various studies to solve the above problems, the present inventors have found that an aqueous medium containing a specific copolymer resin and colloidal silica. The inventors have found that a subbing agent can achieve the object, and completed the present invention. That is, the aqueous undercoating agent for an inorganic porous substrate of the present invention comprises (a) an ethylenically unsaturated carboxylic acid 2 to 20% by weight, and (b) another monomer 80 to 98% by weight in an aqueous medium. A water-based undercoating agent for an inorganic porous substrate, which comprises a copolymer resin obtained by copolymerization of a monomer mixture and colloidal silica, and comprises 5% by weight of the copolymer resin.
The above is characterized by being present in a solubilized state.

Of the starting unsaturated monomers for preparing the copolymer resin of the present invention, the (a) ethylenically unsaturated carboxylic acid is a monocarboxylic acid or a polycarboxylic acid. However, it is preferably a mono- or di-olefinically unsaturated carboxylic acid having 3 to 5 carbon atoms. In particular, acrylic acid, methacrylic acid, and itaconic acid are preferable. The amount of ethylenically unsaturated carboxylic acid is 2 to 20% by weight, preferably 5 to 10% by weight, based on the total monomer mixture.
Is. If the amount of the monomer is too small, alkali and / or
Alternatively, sufficient solubilization (solubilization) cannot be performed when solubilizing treatment is performed by adding an organic solvent, and sufficient smoothness and adhesion of the film cannot be obtained. On the other hand, if the amount of the same monomer is too large, the hydrophilicity of the copolymer resin becomes too high and the water resistance of the film is lowered, so that the adhesion to the coated object as the undercoating agent is lowered.

The monomer (b) is other than the above-mentioned monomer (a), and is an alkyl ester of acrylic acid or methacrylic acid having 1 to 10 carbon atoms (for example, methyl ester of acrylic acid or methacrylic acid). , Ethyl, isopropyl, n-propyl, n-butyl, isobutyl, t
-Esters such as butyl), vinyl aromatic compounds (eg styrene), vinyl halides (eg vinyl chloride, vinyl bromide, vinylidene chloride), saturated carboxylic acid vinyl esters (eg vinyl acetate, vinyl propionate), acrylonitrile, methacrylic acid. Ronitrile, ethylene, butadiene, monoolefinic unsaturated carboxylic acid amides (eg acrylic acid amide, methacrylic acid amide, itaconic acid amide, etc.), N-alkyl and / or N-alkylol of monoolefinic unsaturated carboxylic acid amides Derivatives (eg N-methylacrylamide, N
-Isobutyl acrylamide, N-methylol acrylamide, N-methylol methacrylamide, N-ethoxymethyl acrylamide), mono-olefinically unsaturated sulfonic acid (eg vinyl sulfonic acid, methyl acrylamide propane sulfonic acid, etc.), hydroxyethyl acrylate, hydroxypropyl methacrylate , An epoxy group-containing monomer (eg, glycidyl acrylate,
Glycidyl methacrylate, allyl glycidyl ether, etc.), fluorine-containing monomers (eg, perfluoromethyl methacrylate, perfluorobutyl methacrylate, etc.) and the like. Particularly preferred monomer (b) is an alkyl ester of acrylic acid or methacrylic acid having 1 to 8 carbon atoms and vinyl acetate. Two or more kinds of these monomers (b) may be contained in the copolymer.

The amount of the monomer (b) is 80 to 98% by weight,
It is preferably in the range of 90 to 95% by weight. When the amount of the monomer (b) is less than the above range, the water resistance tends to decrease, and when the amount of the monomer (b) is more than the above range, the water solubility is decreased. The material adhesion will be reduced. As the monomer (b), a carbonyl group-containing unsaturated monomer having at least one aldo group or keto group and one polymerizable unsaturated double bond in the molecule, for example, acrolein or diene. Acetone acrylamide, formyl styrene, vinyl alkyl ketones having 4 to 7 carbon atoms (for example vinyl methyl ketone,
Vinyl ethyl ketone, vinyl butyl ketone, etc.), general formula

[0009]

[Chemical 1]

(In the formula, R ¹ is H or CH ₃ , R ² is H or an alkyl group having 1 to ³ carbon atoms, R ³ is an alkyl group having 1 to ³ carbon atoms, and R ⁴ is 1 to 1 carbon atoms. Acrylic (or methacryl) oxyalkylpropenal represented by 4 alkyl groups), diacetone acrylate, acetonyl acrylate, diacetone methacrylate, 2-
Hydroxypropyl acrylate acetyl acetate,
Butanediol-1,4-acrylate acetyl acetate, etc. are mentioned. Two or more kinds of these monomers (b) may be contained in the copolymer. Particularly preferred monomers thereof are diacetone acrylamide, acrolein and vinyl methyl ketone.

Copolymerization for producing a copolymer resin using each of the above-mentioned monomer mixtures (a) and (b) is carried out by solution polymerization or emulsion polymerization. The solvent used for the solution polymerization is not particularly limited, but a water-soluble or hydrophilic solvent is preferable from the viewpoint of miscibility with the produced copolymer resin and water. Specific examples thereof include monoalcohols having 1 to 4 carbon atoms, such as methyl alcohol,
Ethyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol and t-butyl alcohol; ethylene glycol and derivatives thereof, such as ethylene glycol monomethyl ether, monoethyl ether, monopropyl ether, monobutyl ether; diethylene glycol and derivatives thereof, For example, diethylene glycol monomethyl ether, the same monoethyl ether, the same monopropyl ether, the same monobutyl ether; other 1,4-dioxane, water and the like can be mentioned. One type of these solvents may be used, or two or more types may be appropriately used in combination. As the solvent, those having a boiling point of 200 ° C. or less are generally preferable from the viewpoint of distilling after the polymerization or drying speed.

The polymerization initiator for solution polymerization is preferably oil-soluble. Specific examples thereof include azo initiators such as azobisisobutyronitrile and azobisvaleronitrile; organic peroxide initiators such as benzoyl peroxide, lauroyl peroxide and t-butyl peroxide; and other peroxides. Inorganic peroxide type initiators such as hydrogen and ammonium persulfate can also be used. These initiators may be used alone or in appropriate combination of two or more. Further, a reducing agent such as an organic amine may be used in combination with these initiators and used as a redox initiator.

The copolymer resin can also be produced by emulsion polymerization. For the emulsion polymerization, a method in which an emulsifier is used to carry out the polymerization with a water-soluble polymerization initiator, or a soap-free polymerization is used. A method of causing polymerization or the like is used. Examples of the emulsifier include various anionic, cationic and nonionic emulsifiers, and further polymeric emulsifiers. A particularly preferred emulsifier is a carbonyl group-containing polymer emulsifier described in JP-A-64-48801, which is a publication of a patent application relating to the invention of the present inventors (a part).

The polymerization initiator used in the emulsion polymerization is preferably an inorganic peroxide such as potassium persulfate, ammonium persulfate or hydrogen peroxide. These inorganic peroxides include
You may use together with the reducing agent as mentioned above as a redox initiator. If an epoxy group-containing monomer is used as a copolymer component and the epoxy group may open during polymerization, neutralize the reaction system in the presence of an alkali such as sodium hydroxide. While carrying out the polymerization, it is preferable.

Various methods can be used as the method of supplying the monomers in the emulsion polymerization. For example, the batch charging method,
Various methods such as a monomer addition method and an emulsion addition method can be used. Further, a seed polymerization method in which the composition of the monomer to be added is sequentially changed, or a power feed polymerization method or the like can also be used, and when such a method is used,
The degree of solubilization can be adjusted by changing the copolymer composition of the central part of the produced copolymer resin particles and the outside.

A chain transfer agent is preferably used in the emulsion polymerization. This is because the copolymer resin generally obtained by emulsion polymerization has a high molecular weight, and therefore, when it is solubilized in water by addition of an alkali and / or an organic solvent, it is difficult to achieve sufficient solubilization. This is because when the transfer agent is used, the molecular weight of the produced copolymer resin can be reduced and the solubilization is facilitated. Examples of the chain transfer agent include various mercaptans,
Examples include α-methylstyrene, alkyl halides and alcohols. The amount used is 0.03 to 5% by weight based on all the monomers.

The copolymer resin prepared by the solution polymerization or emulsion polymerization described in detail above should have a solubilization rate of 5% by weight or more by the addition of an alkali and / or an organic solvent. Solubilized, but solubilized (ie, addition of alkali and / or organic solvent)
May be before starting the copolymerization for producing the copolymer resin, or at the time of the copolymerization or after the completion of the copolymerization. In any case, the "solubilization rate" described in the present specification means the solubilization rate measured by the following method.

Solubilization treatment was carried out under exactly the same conditions as the actual solubilization treatment to prepare a copolymer resin, and the obtained copolymer resin was diluted with water to a nonvolatile content of 15% by weight. After that, the diluted solution is subjected to centrifugal acceleration of 1.8 × 10 ⁵ g.
When the non-volatile content in the obtained supernatant is measured as w parts by weight, and the non-volatile content in the above-mentioned diluent used for centrifugation is measured as W parts by weight, The solubilization rate represented by the following formula.

Solubilization rate = w / W × 100 (wt%) Therefore, for example, before polymerization for producing a copolymer resin,
Or, in the case where the copolymerization is carried out by adding an alkali and / or an organic solvent to the polymerization system during the polymerization, the polymerization product containing the produced copolymer resin obtained by the copolymerization is When the solubilization rate is already 5% by weight or more as it is, it is not necessary to add the alkali and / or organic solvent for the solubilization treatment again.

The alkali used for the solubilization treatment is an inorganic water-soluble alkali, such as sodium hydroxide or potassium hydroxide; or an inorganic salt which exhibits alkalinity when dissolved in water, such as sodium hydrogen carbonate or pyrophosphate. Sodium and the like; other examples include aqueous ammonia and organic amines. Addition of alkali is as described above.
It does not necessarily have to be after the formation of the copolymer, and in some cases, (a) the ethylenically unsaturated carboxylic acid before the copolymerization for forming the copolymer resin is neutralized by adding an alkali, Copolymerization may be performed. Also,
The addition of the alkali in the case of solution polymerization may be performed in the presence of the solvent used for the copolymerization, or the alkali may be added as an aqueous solution to the copolymer resin after the solvent is distilled off to partially or completely. It may be solubilized in water. The amount of alkali used may be an amount that completely neutralizes the carboxyl groups in the copolymer resin or an amount that partially neutralizes the carboxyl groups.

The organic solvent used for the solubilization treatment may be supplementarily added when it cannot be sufficiently solubilized in water by only adding an alkali, or may be solubilized by adding only an organic solvent. Further, in the case of producing a copolymer resin by solution polymerization, when the organic solvent used as the polymerization solvent can serve as an organic solvent for solubilization as it is, addition of an organic solvent is newly added. May not be necessary, and in some cases, an organic solvent different from the organic solvent used as the polymerization solvent may be added. Examples of the organic solvent used include the same ones as described above as the solvent used for the solution polymerization. Particularly preferred organic solvents are texanol, ethylene glycol monobutyl ether, ethylene glycol monoethyl ether and their acetates, benzyl alcohol, butyl carbitol acetate, 2,2,2.
4-trimethyl-1,3-pentanediol and the like can be mentioned.

In order to improve the water resistance of the copolymer resin, at least one aldo group in the molecule, which is exemplified as the other monomer of the above (b) as a constituent monomer of the copolymer resin, or Copolymerization is carried out using a carbonyl group-containing unsaturated monomer having a keto group and one polymerizable unsaturated double bond, and then a hydrazine derivative having at least two hydrazino groups in the molecule is added. Is effective.

The carbonyl group-containing unsaturated monomer is preferably used in a proportion of 0.5 to 30% by weight, more preferably 1 to 20% by weight in the total monomer mixture. If the amount of the monomer is too small, the content of the aldehyde group or keto group in the copolymer resin is too small, and even if a hydrazine derivative is added, sufficient water resistance and solvent resistance can be expected to improve. Absent. On the other hand, if the amount of the monomer is too large, the alkali resistance, weather resistance, etc. of the film tend to decrease.

The hydrazine having at least two hydrazino groups in the molecule is, for example, 2 to 10,
In particular, dicarboxylic acid dihydrazides having 4 to 6 carbon atoms (for example, oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide,
Adipic acid dihydrazide, sebacic acid dihydrazide, maleic acid dihydrazide, fumaric acid dihydrazide, itaconic acid dihydrazide), aliphatic water-soluble dihydrazine having 2 to 4 carbon atoms (for example, ethylene-1,2-dihydrazine, propylene-1) , 3-dihydrazine, butylene-1,4-dihydrazine and the like).

In addition, the general formula,

[0026]

[Chemical 2]

(In the formula, X is a hydrogen atom or a carboxyl group, Y is a hydrogen atom or a methyl group, A is each unit of acrylamide, methacrylamide, acrylic acid ester, methacrylic acid ester or maleic anhydride. , B is a unit of a monomer copolymerizable with acrylamide, methacrylamide, acrylic acid ester, methacrylic acid ester or maleic anhydride, and k, m and n are the following formulas 2 mol% ≤ k ≤ A polymer represented by 100 mol% 0 mol% ≦ (m + n) ≦ 98 mol% (k + m + n) = 100 mol% is also used as the hydrazine derivative. Such polymers are described in detail, for example, in JP-A-55-6535.

The mixing ratio of the hydrazine derivative is such that the ratio of the carbonyl group contained in the copolymer resin and other additives (specifically, the resin aqueous dispersion described later) to the hydrazino group contained in the undercoating agent is The molar ratio is preferably 0.2 to
The ratio is 5.0, and more preferably 0.3 to 2.0. If the proportion of the hydrazine derivative is too small, it is not possible to improve the water resistance because the resins are not sufficiently crosslinked, and even if the proportion is too large, there is an effect of improving the water resistance corresponding to it. Not only will it not be obtained, but the coating will be opaque and prone to brittleness.

The aqueous undercoating agent of the present invention contains the above-mentioned copolymer resin and colloidal silica. The colloidal silica referred to in the present invention is obtained by dispersing particles having SiO ₂ as a basic unit in water. Point Particle size is 4-100mμ
Is preferable from the viewpoint of good adhesion to the substrate. Examples of the colloidal silica used in the present invention include those sold under the trade name of "Snowtex" by Nissan Chemical Industries.

The blending ratio of the copolymer resin and the collodal silica is 95/5 to 50/50, preferably 9 by weight of solid content.
It is 0/10 to 60/40. If the amount of colloidal silica is too small, the adhesion between the base material surface and the undercoat material is not sufficient, and if the amount of colloidal silica is too large, the storage stability of the undercoat material is reduced and the water resistance of the film is reduced. , Hot water resistance and frost resistance are reduced. The mixing of the copolymer resin and the colodal silica may be performed before or after the solubilization treatment by adding the above-mentioned alkali and / or organic solvent.

In the present invention, another resin aqueous dispersion may be added for the purpose of improving the water resistance and alkali resistance of the film, adjusting the viscosity, etc., and the resin aqueous dispersion is obtained by synthesis. It is an aqueous emulsion of synthetic resins or of a wide variety of natural resins, with synthetic resin emulsions obtained by emulsion polymerization being preferred. The synthetic resin aqueous dispersion obtained by emulsion polymerization is, as is generally known, an emulsifier, a reactive emulsifier or a protective colloid as a dispersant, and an unsaturated monomer in water using a water-soluble initiator. It can be obtained by (co) polymerization. Examples of the unsaturated monomer include acrylic acid,
For the purpose of methacrylic acid, various esters thereof, vinyl aromatic compounds such as styrene, vinyl halides, acrylonitrile, methacrylonitrile, saturated carboxylic acid vinyl esters, conjugated dienes, unsaturated hydrocarbons such as ethylene and propylene. A copolymer resin aqueous dispersion, which is appropriately combined and used, is usually preferably used.

In addition to the resin aqueous dispersion obtained by emulsion polymerization, there are, for example, polyurethane resin emulsion, alkyd resin emulsion, bisphenol type epoxy resin emulsion, etc., and these resin aqueous emulsions should be used as the resin aqueous dispersion. You can

A particularly preferred aqueous resin dispersion is 0.5 to 20% by weight of the carbonyl group-containing unsaturated monomer exemplified as the component (b); the ethylenically unsaturated carboxylic acid exemplified as the component (a). Acid 0 to 10% by weight; acrylic acid or methacrylic acid alkyl ester having 1 to 10 carbon atoms exemplified as the component (b), acrylonitrile, methacrylonitrile, vinyl aromatic compound, vinyl halide, saturated carboxylic acid By emulsion polymerization of a monomer mixture of 70 to 99.5% by weight of at least one unsaturated monomer selected from vinyl ester, ethylene and butadiene; and 0 to 15% by weight of other monomers other than them. It is an aqueous dispersion of the resulting copolymer resin.

The carbonyl group-containing unsaturated monomer used in this case is the same as the carbonyl group-containing unsaturated monomer exemplified as the preferable component (b) in the case of the above-mentioned copolymer resin. A copolymer resin obtained by copolymerizing an aqueous resin dispersion containing the unsaturated monomer as a constituent with a carbonyl group-containing unsaturated monomer as a constituent unit of the copolymer resin to be solubilized. The aqueous undercoating agent of the present invention using is a complex cross-linking bond between the copolymer resins, between the copolymer resins forming the resin aqueous dispersion, and between the two resins through the hydrazine derivative. Therefore, the physical properties of the crosslinked film are further improved.

The mixing ratio of the copolymer resin in the present invention and the resin aqueous dispersion may be arbitrary, but is preferably 10/0 to 2/8, more preferably 10 in terms of solid content weight ratio.
/ 0 to 3/7. If the proportion of the copolymer resin is too low, the film may be formed on the surface layer of the base material, and the effect of improving the adhesion, smoothness and gloss of the film to the base material may not be sufficiently obtained.

The method of blending the copolymer resin and the resin aqueous dispersion is not particularly limited. For example, to an organic solvent solution containing a copolymer resin obtained by solution polymerization, after adding an alkaline solution, the solvent may be distilled off and then the resin aqueous dispersion may be added, or the solvent may be distilled off. May be added without. In addition, when the copolymer resin is obtained by emulsion polymerization, an alkali and / or organic solvent may be added to the aqueous dispersion of the copolymer resin to solubilize it, and then the aqueous resin dispersion may be added. . Further, the copolymer resin and the resin aqueous dispersion may be mixed and then the alkali and / or the organic solvent may be added.

In the present invention, the solubilization treatment of the copolymer resin prepared by solution polymerization or emulsion polymerization when colloidal silica, a hydrazine derivative or an aqueous resin dispersion is added is carried out by adding colloidal silica to the copolymer resin. as well as/
Alternatively, it may be before mixing the hydrazine derivative and / or the aqueous resin dispersion, during the mixing, or even after the mixing.

Further, in the present invention, in the system using a copolymer resin obtained by polymerizing using a carbonyl group-containing unsaturated monomer as the component (b) and a hydrazine derivative, the reaction between the carbonyl group and the hydrazino group Progresses with drying and film formation, but gelation may occur because it is slightly performed in the aqueous phase. In order to prevent this, the boiling point containing a carbonyl group based on an aldo group or keto group is 200 ° C.
The following low molecular weight compounds (aldehydes or ketones) may be added. The boiling point thereof is preferably 120 ° C. or lower, and more preferably 100 ° C. or lower.

This is because, under the condition that a large amount of water is present, such as during storage of the water-based primer of the present invention or before drying,
The compounded low molecular weight aldehydes and ketones react with the hydrazino group of the hydrazine derivative to block the hydrazino group, effectively blocking the cross-linking reaction between the polymers and stopping the gelation of the resin. It is considered that the gelation time can be extended.

Specific examples of the aldehydes or ketones include, for example, β-hydroxyethyl methyl ketone (at 182 ° C.), acetaldehyde (at 21 ° C.), propionaldehyde (at 49 ° C.), butyraldehyde (at 75 ° C.). , Valeraldehyde (103 ° C of the same), isovaleraldehyde (93 ° C of the same), pivalinaldehyde (7 of the same)
5 ° C), capronaldehyde (the same 131 ° C), heptaldehyde (the same 153 ° C), glyoxal (the same 51 ° C)
℃), succindialdehyde (same 170 ℃), acrolein (same 52 ℃), propiol aldehyde (same 60)
℃), crotonaldehyde (105 ℃), acetone (56 ℃ same), ethyl methyl ketone (80 ℃ same), methyl propyl ketone (102 ℃ same), isopropyl methyl ketone (95 ℃ same), butyl methyl ketone (same) 127
° C), isobutyl methyl ketone (117 ° C of the same), pinacolone (106 ° C of the same), diethyl ketone (102 ° C of the same),
Butyrone (144 ° C), diisopropyl ketone (1: 1)
24 ° C.), methyl vinyl ketone (81 ° C. same), acetoin (148 ° C. same) and the like. These aldehydes or ketones may be used alone or in combination of two or more.

A film-forming aid, a pigment, a filler, a wetting agent and the like can be added to the aqueous undercoating agent of the present invention.

[0042]

EXAMPLES Hereinafter, copolymer resin preparation examples, resin aqueous dispersion preparation examples, examples and comparative examples will be described in detail. The "parts" and "%" described in these examples are on a weight basis. Copolymer Resin Preparation Example 1 After the inside of a reaction vessel equipped with a temperature controller, an anchor type stirrer, a reflux condenser, a thermometer and a nitrogen inlet tube was replaced with nitrogen, 130 parts of ethylene glycol monobutyl ether was charged therein. .

Separately, the following composition was prepared as a feed. Feed material Ethylene glycol monobutyl ether 110 parts Acrylic acid 5 parts Methacrylic acid 5 parts Methyl methacrylate 60 parts Butyl acrylate 30 parts Benzoyl peroxide 3 parts Next, while maintaining the inside of the reaction vessel at 90 ° C. Was continuously fed in small portions over 3 hours.
After the end of the supply, the same temperature was maintained for 2 hours to complete the polymerization.

This solution was concentrated by distillation until the nonvolatile content became 60%, and then 52 g of a 10% aqueous sodium hydroxide solution was added to obtain an ethylene glycol monobutyl ether solution of a copolymer resin having a nonvolatile content of 45%. Then, 30 parts of a mixture of ethylene glycol monobutyl ether and water was distilled off from the obtained solution using a rotary evaporator, and then water was added to the non-volatile part 20%, p.
A copolymer resin solution of H9 was obtained.

Copolymer Resin Preparation Example 2 The same procedure as in Preparation Example 1 was conducted except that the monomer composition of the feed and the polymerization solvent were changed as shown in Table 1. Copolymer Resin Preparation Example 3 In a reaction vessel similar to that used in Preparation Example 1 above, the following materials were charged.

50 parts of water 35% aqueous solution of sulfuric acid half ester sodium salt of p-nonylphenol with 20 mol of ethylene oxide (referred to as “anionic emulsifier A”) 2 parts p-nonylphenol with 25 mol of ethylene oxide (“nonionic emulsifier B”) The following mixture was prepared as a feed I separately.

Feed I Water 50 parts 35% aqueous solution of the above anionic emulsifier A 4 parts 20% aqueous solution of the above nonionic emulsifier B 2 parts Methyl methacrylate 60 parts Ethyl acrylate 10 parts Butyl acrylate 20 parts Acrylic Acid 5 parts Methacrylic acid 5 parts t-Dodecyl mercaptan 0.7 parts

Separately, an aqueous solution prepared by dissolving 0.7 part of potassium persulfate in 20 parts of water was prepared as the feed II. After purging the inside of the reaction vessel with nitrogen gas, 10% of the feed I was added to the charge, and the mixture was heated to 90 ° C. Then, 10% of the feed II was injected into the reaction vessel, and then the remaining feeds I and II were fed in parallel little by little over 3.5 hours. After the end of the supply, the temperature was kept at 90 ° C. for 1.5 hours to complete the emulsion polymerization. The resin aqueous dispersion obtained as described above has a nonvolatile content of 2
It was diluted with water to 0%, and then a 25% aqueous ammonia solution was added to adjust the pH to 9.

Copolymer Resin Preparation Examples 4, 6 to 8 Same as Preparation Example 3 except that the monomer composition of the feed and the chain transfer agent present in the polymerization system were changed as shown in Tables 1 and 2. I did.

Copolymer Resin Preparation Example 5 The following was charged into a reaction vessel similar to that used in Preparation Example 1 above. Water 50 parts Na lauryl sulfonate 2 parts 35% aqueous solution of anionic emulsifier A 3 parts Separately, the following mixture was prepared as a feed I.

Water 50 parts Na lauryl sulfonate 1 part 35% aqueous solution of the above anionic emulsifier A 2 parts Methyl methacrylate 45 parts Ethyl acrylate 10 parts Butyl acrylate 20 parts 2 Hydroxyethyl acrylate 5 parts Acrylic acid 5 parts Methacrylic Acid 10 parts Diacetone acrylamide 5 parts t-Dodecyl mercaptan 0.5 parts

Separately, an aqueous solution prepared by dissolving 0.7 part of potassium persulfate in 20 parts of water was prepared as the feed II.
After purging the inside of the reaction vessel with nitrogen gas, 10% of the feed I was added to the charge, and the mixture was heated to 90 ° C. Then, 10% of the feed II was injected into the reaction vessel, and then the remaining feeds I and II were fed in parallel little by little over 3.5 hours. After the end of the supply, the temperature was kept at 90 ° C. for 1.5 hours to complete the emulsion polymerization. The resin aqueous dispersion obtained as described above has a nonvolatile content of 2
The mixture was diluted with water to 0%, 10% sodium hydroxide was added to adjust the pH to 9, and 3 parts of ethylene glycol monobutyl ether was further added.

Copolymer Resin Preparation Example 9 Same as Preparation Example 5 except that the monomer composition of the feed was changed as shown in Tables 2 and 3.

[0054]

[Table 1]

[0055]

[Table 2]

Resin Aqueous Dispersion Preparation Example A Into the same reaction vessel used in Preparation Example 1 above, the following materials were charged. Water 225 parts 35% aqueous solution of the anionic emulsifier A 5 parts 20% aqueous solution of the nonionic emulsifier B 20 parts Separately, the following mixture was prepared as the feed I.

Feed I Water 200 parts 35% aqueous solution of the above anionic emulsifier A 25 parts Acrylic acid 8 parts Diacetone acrylamide 8 parts Butyl acrylate 200 parts Styrene 250 parts Separately, as a supply II, in 85 parts water A solution having 2.5 parts of potassium persulfate dissolved therein was prepared.

After purging the reaction vessel with nitrogen gas, 10% of feed I was added to the charge and the mixture was heated to 90 ° C. Then, 10% of the feed II was injected into the reaction vessel, and the remaining feeds I and II were fed into the reaction vessel in small amounts uniformly in parallel over 3 to 3.5 hours. After the end of the supply, the temperature was raised to 90 ° C. and the temperature was kept for another 1.5 hours to carry out emulsion polymerization. The produced resin aqueous dispersion had a nonvolatile content of 47% and a minimum film-forming temperature of 20 ° C.

Example 1 70 parts of ethylene glycol monobutyl ether solution having a nonvolatile content of 20% obtained in Preparation Example 1 of copolymer resin, Snowtex C (trade name of Nissan Chemical Industries, Ltd.) as colloidal silica and adipic acid dihydrazide 1.5 parts of 20% aqueous solution were mixed.

Regarding the dry film of the obtained aqueous primer,
The adhesion, unevenness of topcoat, water resistance, warm water resistance, and frost damage resistance were tested by the following test methods, and the evaluation results were as shown in Table 3. As a test piece, a 5 cm × 10 cm calcium silicate plate was applied such that the coating amount after drying was 20 g / m ² and dried at 100 ° C. for 10 minutes to form a film. Note Any evaluation results were expressed by the evaluation of the calcium silicate board evaluation / Density 0.78 g / cm ³ for calcium silicate board of density 0.6 g / cm ^3.

Adhesion: The test piece was cut into 5 × 5 crosses at 3 mm intervals with a cutter knife, a polyester adhesive tape was pressure-bonded, and then peeled off to examine the remaining state of the coating film. ⊚: The coating film does not peel at all ◯: The coating film peels slightly Δ: The coating film partially peels ×: The coating film completely peels

Topcoat unevenness: The topcoat paint was applied as a topcoat paint to the test piece so that the film thickness after drying was 50 μm and dried at 100 ° C. for 10 minutes to form a film. The appearance was visually evaluated. Topcoat paint composition Water 30.0 parts Demol EP (manufactured by Kao) 2.0 parts Nopco 8034 (manufactured by San Nopco) 0.3 parts Titanium oxide (rutile type) 45.0 parts Acronal YJ-2770D (Mitsubishi Petrochemical Birdishe 146.7 parts Texanol (manufactured by Eastman Kodak) 11.5 parts 5% -Adecan UH-420 (manufactured by Asahi Denka Co., Ltd.) 1.0 part ◎: No unevenness ○: Some unevenness △: Some unevenness × : With lifting

Water resistance: The test piece was immersed in water at 20 ° C. for 5 days and then dried at room temperature for 2 days, and the same evaluation as the adhesion was performed. Warm water resistance: After immersing the test piece in warm water at 40 ° C. for 5 days,
After drying for 2 days at room temperature, the adhesion was examined by the same method as above. Freezing resistance: immersion in water at 5 ° C. for 2 hours → freezing in air at −20 ° C. for 2 hours as one cycle, after 200 cycles, after drying at room temperature for 2 days, adhesion was examined by the same method as above. .

Examples 2 to 12 and Comparative Examples 1 to 5 The types and amounts of the copolymer resin, the resin aqueous dispersion, the hydrazine derivative and the colloidal silica were changed as shown in Tables 5 to 8 and the formulation was changed. Ethylene glycol monobutyl ether was blended in the respective amounts, and an aqueous undercoating agent was prepared in the same manner as in Example 1 except that the physical properties of the film were tested.

Tables 3 to 6 show the composition ratio (parts) and the like of the aqueous undercoating agents obtained in each of these Examples and Comparative Examples, and the test results of the film physical properties.

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[Table 3]

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[Table 4]

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[Table 5]

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[Table 6]

Notes to Tables 3 to 6 * 1 ... Adipic acid dihydrazide * 2 ... Maleic acid dihydrazide * 3 ... Snowtex C (Colloidal silica manufactured by Nissan Chemical Industries Ltd., solid content 20%) * 4 ... Snowtex N (Colloidal silica manufactured by Nissan Chemical Industries, solid content 20%) * 5 ... Snowtex S (Colloidal silica manufactured by Nissan Chemical Industry, solid content 30%) Tables 3 to 6 As is apparent from the above, the undercoating agent of the example is superior to that of the comparative example in terms of adhesion, unevenness of topcoating, water resistance, warm water resistance, and frost damage resistance.

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The water-based undercoating agent of the present invention is excellent in water resistance, warm water resistance, adhesion to a substrate and frost damage resistance, and can give an excellent film which does not cause unevenness of the top coating.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Yoshinori Kato, 1000 Kawajiri-cho, Yokkaichi-shi, Mie Mitsubishi Yuka Birdishe Co., Ltd. (72) Ryutaro Hayashi, 1000, Kawajiri-cho, Yokkaichi-shi, Mie Mitsubishi Yuka Birdishe Co. Within

Claims (4)

[Claims] 1. A copolymer obtained by copolymerizing a monomer mixture consisting of (a) ethylenically unsaturated carboxylic acid 2 to 20% by weight (b) other monomer 80 to 98% by weight in an aqueous medium. A water-based undercoating agent for an inorganic porous substrate, comprising a copolymer resin and colloidal silica, which comprises 5% by weight of the copolymer resin.
An aqueous undercoating agent for an inorganic porous substrate, wherein the above is present in a solubilized state. 2. The water-based undercoating agent for inorganic porous substrates according to claim 1, wherein the blending ratio of the copolymer resin and colloidal silica is 95/5 to 50/50 in terms of solid content weight. . 3. The (b) other monomer in the monomer mixture contains in the molecule at least one carbonyl group based on an aldo group or keto group, and one polymerizable double bond. A carbonyl group-containing unsaturated monomer having a bond, the amount of which is 0.5 to 30% by weight of the total monomer mixture, and the primer is at least 2 in the molecule. The hydrazine derivative having a hydrazino group is mixed, and the aqueous undercoating agent for an inorganic porous substrate according to claim 1, which is characterized in that 4. The aqueous undercoating agent for inorganic porous substrates according to claim 3, wherein the ratio of the carbonyl group to the hydrazino group contained in the undercoating agent is 0.2 to 5.0 in terms of molar ratio.