JPH09328375A - Water-based groundwork treatment agent for ceramic-based siding board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject groundwork treatment agent excellent in water resistance of the film thereof, comprising water-glass, a tetramethoxysilane oligomer and a carboxyl-bearing synthetic resin emulsion. SOLUTION: This water-based groundwork treatment agent for ceramic-based siding boards comprises (A) water-glass, (B) a tetramethoxysilane oligomer formed by hydrolysis and condensation reaction of tetramethoxysilane and (C) a carboxyl-bearing synthetic resin emulsion. The component C is esp. pref. a synthetic resin emulsion which is prepared by emulsion copolymerization of a vinyl monomer (e.g. methyl methacrylate) using carboxyl-bearing water-soluble or water-dispersible polymer and/or its salt (e.g. acrylic acid/ethyl acrylate copolymer) as an emulsifier, because this emulsion is excellent in admixing stability with the water-glass. This groundwork treatment agent is inexpensive and highly safe, also being favorable in the adherability of a topcoating material thereto.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an aqueous base treatment agent for ceramic siding boards.

[0002]

2. Description of the Related Art Ceramic siding boards are used as wall materials for interiors and exteriors, and are usually coated with a surface treatment agent to improve the adhesion of top coat paint and the finish appearance. . The undercoating agent used for such a purpose mainly has good adhesion to the substrate,
It has good permeability to the base material and has a reinforcing effect on the surface of the base material.
Various performances such as good adhesion of the top coating to the surface coated with the base treatment agent are required.

Conventionally, a lot of organic solvent-based ones have been used as a surface treatment agent, which include a low-molecular weight moisture-curable urethane and a solvent type resin.
Since it contains a volatile organic solvent, there are problems such as fire hazard, adverse effects on human body, and environmental pollution.

In recent years, it has been studied to use a water-soluble resin, an emulsion, a water-dispersible resin or the like as a base treatment agent. However, in general, the water-soluble resin is poor in water resistance and alkali resistance, and is therefore used as a top coat. There is a drawback that the adhesion with is insufficient.

Japanese Unexamined Patent Publication (Kokai) No. 4-285682 discloses an aqueous base treating agent comprising a composition containing a synthetic resin emulsion having a carboxyl group and water glass.
The composition has relatively good properties as a surface treatment agent, but in use, in order to form a film having sufficient water resistance, alkali resistance, etc., after application, the temperature is about 100 ° C. or higher. It is necessary to heat at a high temperature, and a surface treatment agent that can form a film having sufficient performance at a lower temperature is desired. Further, the film formed by the undercoating agent is desired to be further improved in terms of the adhesiveness of the topcoat paint.

[0006]

The main object of the present invention is to:
Only by drying under relatively low and moderate temperature conditions, a film with excellent alkali resistance, water resistance, etc. can be formed, and the film also has excellent adhesion to the topcoat paint. Another object of the present invention is to provide a water-based base treatment agent for ceramic siding boards.

[0007]

Means for Solving the Problems The present inventor has earnestly studied in view of the above-mentioned current situation. As a result, in the composition containing the synthetic resin emulsion having a carboxyl group and water glass, further, according to the aqueous composition containing the tetramethoxysilane oligomer, the curing reaction of the water glass is caused by the presence of the tetramethoxysilane oligomer. Even when it is accelerated and dried under a relatively low temperature condition of about 45 ° C., a strong bond is formed between the siding board base material and each component, and the action of each component is combined, resulting in water resistance, A film with excellent alkali resistance,
At the same time, it was found that the adhesion to the topcoat paint was also improved, and it became a low-cost and highly safe undercoating agent that can sufficiently satisfy various required properties for the undercoating agent for ceramic siding boards. . Further, when water glass and a tetramethoxysilane oligomer are pre-condensed and combined with a synthetic resin emulsion having a carboxyl group to be used as a base treatment agent, the curability is further improved, and the water resistance, It has been found that various properties such as hot water resistance become better. The present invention has been completed based on these findings.

That is, the present invention relates to an aqueous undercoating agent for ceramic siding boards, which contains water glass, a tetramethoxysilane oligomer, and a synthetic resin emulsion having a carboxyl group.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The groundwork treating agent for ceramic siding board of the present invention contains water glass, tetramethoxysilane oligomer, and synthetic resin emulsion having a carboxyl group as active ingredients. Less than,
Each component to be added to the base treatment agent will be described in detail.

(I) Water glass The water glass used in the present invention mainly functions to improve the penetration into the substrate, the adhesion to the substrate, the adhesion, and the reinforcing effect on the substrate surface. And the general formula Na ₂ O.nS
iO ₂ (n = 2 to 4) or general formula K ₂ O · nSiO ₂
It is a concentrated aqueous solution of an alkali silicate represented by (n = 2-4). Water glass is relatively inexpensive and widely used in various fields. Industrially, it is used as sodium silicate.
Specified in IS K1408, SiO ₂ and Na ₂
Depending on the content ratio of O, they are classified into No. 1 to No. 4, but any of them can be used. Particularly, in the above general formula, those having a large n, that is, Nos. 3 and 4 having a relatively small amount of alkali components are advantageous in terms of water resistance.

(Ii) Tetramethoxysilane Oligomer The tetramethoxysilane oligomer to be added to the surface treating agent of the present invention is a partial hydrolysis-condensation product of tetramethoxysilane, and it is suitable to use one having a degree of polymerization of about 2-10. And a polymerization degree of about 4 to 5 is preferable. In the surface treatment agent of the present invention, by blending such a tetramethoxysilane oligomer, a part of the tetramethoxysilane oligomer is condensed with water glass in the curing process of the surface treatment agent to form silanol groups in tetramethoxysilane. It is considered that it contributes to the hardening of water glass and, as a result, accelerates the hardening reaction.

The tetramethoxysilane monomer is highly toxic and has too high activity, and may generate heat or bump at the time of working. However, the tetramethoxysilane oligomer used in the present invention does not have such a problem. In addition, when blended with a base treatment agent, it has excellent workability. or,
Tetramethoxysilane oligomers are more active and more reactive than other oligomers such as tetraethoxysilane oligomers, and by blending them, the curability of water glass is improved. The curing reaction of the water glass sufficiently progresses and a film having excellent water resistance, alkali resistance, and the like can be formed simply by drying under moderate temperature conditions. Further, in the conventional surface-treating agent using water glass, sodium hydroxide was present in the film due to poor curing of water glass, and this was one of the factors that reduced the adhesion of the topcoat film. By mixing the silane oligomer, the hardening of water glass is accelerated and sodium hydroxide is fixed in the film, and the silanol group of tetramethoxysilane reacts with the resin and pigment in the topcoat paint to improve the adhesion of the topcoat paint. Is expected to improve.

The tetramethoxysilane used to obtain the tetramethoxysilane oligomer has the chemical formula: Si (O
CH ₃ ) _4, which can be obtained by a method such as a reaction between silicon tetrachloride and methanol, a reaction between metallic silicon and methanol, etc. Since it can be removed and hydrochloric acid does not form as a by-product and does not cause a problem of equipment corrosion, tetramethoxysilane obtained by reacting metal silicon and methanol is used especially for applications requiring removal of impurities. Is desirable.

The hydrolysis-condensation reaction itself for obtaining the tetramethoxysilane oligomer may be carried out by a known method. For example, a predetermined amount of water is added to the tetramethoxysilane monomer to produce a by-product in the presence of an acid catalyst. Usually, the reaction may be performed at about room temperature to 100 ° C. while distilling off the alcohol. In this reaction, an alcohol such as methanol may be used as a solvent. By this reaction, tetramethoxysilane is hydrolyzed, and furthermore, a liquid tetramethoxysilane oligomer having a number of hydroxyl groups of 1 or less (usually an average degree of polymerization of about 2 to 10, mostly 3 to 4) by a condensation reaction.
7) is obtained as a partially hydrolyzed condensate. The degree of hydrolysis can be appropriately adjusted according to the amount of water used, and the amount of water necessary for hydrolytically condensing all hydrolyzable groups of tetramethoxysilane, that is, alkoxy groups, that is, these It is expressed as a percentage of the actual addition amount with respect to water having a mole number of ½ of the mole number of the group. In the present invention, the degree of hydrolysis of the tetramethoxysilane oligomer is usually selected from about 20 to 80%, preferably about 30 to 60%. If it is less than 20%, the residual ratio of the monomer is high and the productivity is low. On the other hand, if it is more than 80%, the obtained composition tends to gel, which is not preferable.

The partially hydrolyzed condensate thus obtained usually contains about 2 to 10% by weight of a monomer. When this monomer is contained, it is highly toxic, has high activity and is difficult to handle, so that the monomer content is 1% by weight or less,
The monomer is preferably removed so as to be preferably 0.3% by weight or less. This monomer removal can be performed by flash distillation, vacuum distillation, blowing of inert gas, or the like.

(Iii) Synthetic Resin Emulsion Having Carboxyl Group A synthetic resin emulsion having a carboxyl group, which is another component of the surface treating agent of the present invention, is mainly flexible by adjusting the balance of permeability to the substrate. It has a function of improving the properties, durability, coatability, etc., and can be produced by a usual emulsion polymerization method. In particular, as shown below, an emulsion obtained by emulsion copolymerization of α, β-unsaturated carboxylic acid and other vinyl monomers is preferable.

Examples of the α, β-unsaturated carboxylic acid include maleic acid, fumaric acid, crotonic acid, itaconic acid,
Acrylic acid, methacrylic acid, etc. may be used alone or in combination of two or more, and among these, acrylic acid, methacrylic acid, etc. are particularly preferable because of good copolymerizability. By using the α, β-unsaturated carboxylic acid, a carboxyl group is introduced into the synthetic resin emulsion, and the stability of the emulsion, particularly the mixing stability with water glass, can be improved.

Other vinyl-based monomers to be emulsion-polymerized with α, β-unsaturated carboxylic acids are specifically methyl methacrylate, ethyl methacrylate, butyl methacrylate, t-butyl methacrylate, iso-methacrylate.
Butyl, methacrylic acid alkyl esters such as 2-ethylhexyl methacrylate; acrylic acid alkyl esters such as methyl acrylate, ethyl acrylate, butyl acrylate, iso-butyl acrylate, 2-ethylhexyl acrylate, octyl acrylate; styrene, α-
Styrenes such as methylstyrene and vinyltoluene; (meth) acrylonitrile, (meth) acrylamide, n-
Methylol (meth) acrylamide, 2-hydroxyethyl (meth) acrylate, glycidyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, (meth ) Methoxyethyl acrylate, butoxyethyl (meth) acrylate, vinyl acetate, vinyl propionate, vinyl versatate, vinyl chloride and the like can be mentioned. These monomers can be usually used alone or as a mixture of two or more kinds.

The proportion of the monomer component used is 0.5 to 0.5 of the α, β-unsaturated carboxylic acid based on the total amount of the polymerized monomers.
About 10% by weight, other vinyl monomers 99.5
It may be about 90% by weight.

The emulsion polymerization is carried out in an aqueous medium in the presence of an emulsifier. Specific examples of the emulsifier include cationic emulsifiers such as stearylamine hydrochloride, lauryltrimethylammonium chloride, and trimethyloctadecylammonium chloride; potassium oleate, sodium lauryl sulfate, sodium dodecylbenzenesulfonate, sodium alkylnaphthalenesulfonate, dialkylsulfosuccinic acid. Anionic emulsifiers such as sodium, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene alkyl allyl ether sulfate, polyoxyethylene alkyl ether phosphate, polyoxyethylene alkyl allyl ether phosphate; polyoxyethylene alkyl ether, polyoxyethylene Alkyl allyl ether, polyoxyethylene oxypropylene block poly Chromatography, polyethylene glycol fatty acid esters, nonionic emulsifiers such as polyoxyethylene sorbitan fatty acid esters; lauryl betaine, may be mentioned amphoteric emulsifiers such as lauryl dimethyl amine oxide.

As the synthetic resin emulsion used in the present invention, a water-soluble or water-dispersible polymer having a carboxyl group and / or a salt thereof (hereinafter referred to as “oligo soap”)
, Which is obtained by emulsion-copolymerizing a vinyl monomer with an emulsifier), has particularly good miscibility with water glass, and makes it possible to increase the mixing ratio of water glass to synthetic resin emulsion. It is suitable in that respect. Therefore, the use of the emulsion can broaden the applicable range of the base treatment agent. In particular, by increasing the blending ratio of water glass, it has excellent permeability, and can be applied to a high-density base material, a dense base material having a low water content after curing, and the like.

The oligosoap is a monomer having a carboxyl group, such as maleic acid, fumaric acid, crotonic acid,
(Meth) acrylic acid alkyl esters such as itaconic acid, acrylic acid, methacrylic acid, and other copolymerizable vinyl-based monomers such as methyl methacrylate and ethyl acrylate; and hydroxyethyl (meth) acrylate ( Hydroxyalkyl (meth) acrylate; (meth) acrylamide derivatives such as (meth) acrylonitrile and acrylamide; sulfonic acid-based monomers such as sodium vinyl sulfonate and sodium styrene sulfonate; maleic esters such as dibutyl maleate and dioctyl maleate. And others, obtained by copolymerizing with vinyl acetate, styrene and the like. Among the monomers having a carboxyl group, acrylic acid, methacrylic acid and the like have good copolymerization reactivity and can be used particularly preferably.

The oligosoap can be produced by a known method such as bulk polymerization, solution polymerization and suspension polymerization, but usually it is easy to produce by the solution polymerization method. The polymerization conditions may be the same as those of a known method, such as a polymerization temperature of about 50 to 100 ° C. and a polymerization time of about 1 to 8 hours. As the solvent during the solution polymerization, a water-soluble organic solvent such as methanol, ethanol, isopropyl alcohol, methyl ethyl ketone, and butyl cellosolve, water, a mixed solvent of water and the above organic solvent, or the like can be used. As the polymerization initiator, generally used radical polymerization initiators, for example, persulfates such as ammonium persulfate and potassium persulfate, 2,2′-azobisisobutyronitrile,
Azo-based polymerization initiators such as 2,2′-azobis (2,4-dimethylvaleronitrile) and peroxide-based polymerization initiators such as benzoyl peroxide and lauroyl peroxide can be used. Further, a method known as a redox polymerization reaction may be used by combining these polymerization initiators and a reducing agent.

Further, by using an alkyl mercaptan such as n-hexyl mercaptan, n-octyl mercaptan, n-dodecyl mercaptan or t-dodecyl mercaptan as a molecular weight modifier, an alkyl group can be introduced at the terminal. In particular, an oligosoap having a good emulsifying and stabilizing ability can be obtained.

As an emulsifier for emulsion polymerization, oligosoap is preferably used in the form of a salt in which some or all of the carboxyl groups are neutralized with an alkali. As the neutralizing agent, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoethanolamine, diethanolamine,
Water-soluble organic amines such as triethanolamine, ammonia, sodium hydroxide, potassium hydroxide and the like can be used.

The acid value of the oligosoap is preferably 200 or more and the molecular weight is preferably in the range of about 200 to 10,000. Outside of this range, the stability during emulsion polymerization becomes insufficient, and the stability when mixed with water glass is high. The effect of improving sex is also insufficient.

Further, the oligomers having an alkyl sulfide group at the terminal as shown in JP-B-46-10786, JP-B-47-21811, JP-B-47-34832 and JP-B-47-34833 are also included in the present invention. It can be suitably used as an oligo soap.

The emulsion polymerization for obtaining the synthetic resin emulsion to be blended with the base treatment agent is carried out in an aqueous medium at a monomer concentration of usually about 30 to 70% by weight, preferably about 35 to 65% by weight. The amount of the emulsifier used is usually about 0.05 to 10% by weight, preferably about 0.1 to 5% by weight, based on the total amount of the polymerized monomers. As the polymerization initiator, generally used radical polymerization initiators, for example, persulfates such as ammonium persulfate and potassium persulfate, 2,2′-azobisisobutyronitrile, 2,2 ′
-Azo-based polymerization initiators such as azobis (2,4-dimethylvaleronitrile) and peroxide-based polymerization initiators such as benzoyl peroxide and lauroyl peroxide can be used. The amount of the polymerization initiator used is about 0.2 to 10% by weight, preferably 0.
It may be about 3 to 5% by weight. The polymerization reaction is usually 60
It may be performed at a temperature of about 100 ° C for about 2 to 16 hours.

(Iv) Base Treatment Agent The base treatment agent of the present invention is prepared by mixing the above-mentioned tetramethoxysilane oligomer, water glass, and a synthetic resin emulsion having a carboxy group in water as a medium. With such a composition, the respective components effectively act on each other to exert excellent properties as a base treatment agent.

In the surface treatment agent of the present invention, in particular, a tetramethoxysilane oligomer and water glass are condensed in advance,
By compounding this with a synthetic resin emulsion having a carboxyl group, the curability is further improved,
Water resistance, warm water resistance, etc. can be greatly improved. It is considered that this is because the tetramethoxysilane oligomer condensed on the water glass greatly increases the active silanol groups that contribute to the hardening reaction of the water glass and further improves the curability of the water glass.

In order to obtain a surface-treating agent prepared by combining a condensate of water glass and a tetramethoxysilane oligomer in combination with a synthetic resin emulsion, the tetramethoxysilane oligomer is added to an aqueous solution containing water glass to condense the both. After that, a method of mixing this with a synthetic resin emulsion, a method of adding a tetramethoxysilane oligomer to an aqueous solution containing water glass and a synthetic resin emulsion, and condensing the water glass and the tetramethoxysilane oligomer, etc. You can

As a method of adding a tetramethoxysilane oligomer to an aqueous solution containing water glass to cause condensation, for example, the concentration of water glass in the aqueous solution is 5 to 50% by weight.
About 10 to 30% by weight, and the liquid temperature is 0.
The temperature may be set to about 80 ° C., preferably about 0 to 50 ° C., and a necessary amount of tetramethoxysilane oligomer may be added to carry out the condensation reaction. At this time, if the tetramethoxysilane oligomer is added all at once, it is likely to instantly condense with water glass and form a gel. Therefore, it is preferable to gradually add the tetramethoxysilane oligomer gradually over a period of usually about 10 minutes to 1 hour. The pH of the system during the condensation reaction is preferably about pH 8-12 because water glass itself is stable at about pH 8-12 but tends to gel under acidic conditions. The reaction may be carried out usually for about 0.5 to 8 hours, preferably for about 2 to 5 hours, and since the tetramethoxysilane oligomer tends to separate from water, the reaction may be performed when the separated oil component disappears in the aqueous solution. It should be the end point.

Also in the method of adding a tetramethoxysilane oligomer to an aqueous solution containing water glass and a synthetic resin emulsion for condensation, the concentration of water glass and other reaction conditions may be the same as those described above.

In the undercoating agent of the present invention, the characteristics of the undercoating agent such as the permeability to the ceramic siding board and the adhesion to the top coat are determined by the properties of the ceramic siding board to be applied, such as high and low density and surface. However, it is possible to adjust these depending on the resin composition of the synthetic resin emulsion, the state of particles, the mixing ratio with water glass, and the like.

In the surface treatment agent of the present invention, the mixing ratio of each component is not limited to the case where water glass and tetramethoxysilane oligomer are used as they are without being condensed, and the case where they are previously condensed and used. The same range may be used, and usually 5 to 80% by weight of water glass and synthetic resin emulsion 2 based on the solid content in the surface treatment agent.
It may be about 0 to 95% by weight and about 0.05 to 20% by weight of tetramethoxysilane oligomer, preferably 30 to 60% by weight of water glass and 30 to 30% of synthetic resin emulsion.
60% by weight, and tetramethoxysilane oligomer 1 to
It may be about 10% by weight. In the undercoating agent of the present invention, by setting the blending ratio of each component within the above range, each component acts in a well-balanced manner and can exhibit excellent performance as the undercoating agent. If the blending ratio of water glass is too small, the permeability to the substrate is poor,
The effect of water glass is not sufficiently exerted, and on the other hand, if the blending amount is too large, the storage stability becomes poor, which is not preferable. Further, if the blending ratio of the tetramethoxysilane oligomer is too large, the storage stability of the undercoating agent tends to be unstable, and if it is too small, the effect of blending the tetramethoxysilane oligomer cannot be sufficiently exhibited, which is not preferable.

In the surface treatment agent of the present invention, in the above-mentioned mixing ratio, the mixing ratio of the synthetic resin emulsion and the water glass is the solid content in the case of using the usual synthetic resin emulsion having a carboxyl group. Synthetic resin emulsion / water glass (weight ratio) = 50/50 to 95 /
5, preferably about 60/40 to 90/10. If the content of water glass is less than this range, the permeability, fixation, adhesion, etc. to the ceramic siding board will be insufficient, while if it exceeds this range, the mixing stability, storage stability, etc. will be unfavorable.

When using a synthetic resin emulsion obtained by using oligosoap as an emulsifier, the mixing ratio of water glass to the synthetic resin emulsion should be increased because the mixing stability with water glass is particularly good. Is possible, and the ratio of synthetic resin emulsion / water glass is 1
0/90 to 95/5, preferably 40/60 to 90/1
A wide range of about 0 can be set. In this case,
By increasing the blending ratio of water glass, it becomes excellent in permeability, and it can be applied to a high-density base material and a dense base material having a low water content after curing. If the content of water glass exceeds this range, the adhesion with the topcoat paint will be poor, and further the physical properties such as water resistance and alkali resistance of the coating film will be poor, which is not preferable.

The surface treatment agent of the present invention includes, if necessary, a pH adjusting agent such as ammonia water and sodium hydroxide, a viscosity adjusting agent, a water repellent, an ultraviolet absorber, a cross-linking agent, and a film forming aid. , Penetrants, pigments, dyes and the like may be added according to a conventional method.

The solid content concentration of the undercoating agent of the present invention is not particularly limited, but it is usually adjusted to about 20 to 50% by weight using water as a medium. At the time of coating, the lower the viscosity of the surface treatment agent is, the better the penetrability is.
It is suitable to use it after diluting it with water to a concentration of about wt%.

The ceramic siding board to be treated in the present invention is usually prepared by adding fibers such as asbestos, pulp and glass fiber, other additives and water to a hydraulic inorganic binder such as cement, gypsum and slag. Used as a main raw material, i) main raw material mixture, ii) paper making with a paper making machine (or integral extrusion molding), iii) compression molding, iv) curing (normal pressure wet curing or autoclave curing), v) Dry, and
vi) It is obtained through each step of finishing, and if necessary, it is coated with a top coat agent such as acrylic emulsion paint to obtain a product.

The undercoating agent of the present invention is usually applied to a siding board in the process of manufacturing a ceramic siding board, for example, between a compression molding process and a curing process, or between a drying process and a finishing process. Etc. can be painted. The coating amount of the undercoating agent is not particularly limited, but normally, it may be about ²⁰ to 50 g / m ² as the solid content. By heating after coating, curing progresses to form an undercoat with good characteristics, but the undercoating agent of the present invention is excellent in thermosetting property, and can be used with conventional aqueous undercoating. Compared with the agent, a good film can be formed only by drying at a much lower moderate temperature condition.
~ 100 ° C, preferably about 2 ~ 60 ° C
It may be dried for about 5 minutes. When applying the surface treatment agent between the compression molding process and the curing process, in the curing process,
Since it is heated at a temperature of about 70 to 160 ° C. for 24 hours or more, the heat treatment of the undercoating agent may be omitted in some cases. When the heating process of the undercoating agent and the drying of the overcoating agent, the heating in the curing step and the like are combined, the performance of the undercoating agent can be further improved.

The ceramic siding board treated with the undercoating agent of the present invention is coated with an overcoating agent as required in the manufacturing process to obtain a product. For those not coated with a top coat, the top coat is usually applied at the construction site using a general-purpose spray paint.

[0043]

The base treatment agent of the present invention is a low-cost and highly safe aqueous treatment agent that uses water glass. By incorporating a tetramethoxysilane oligomer, the curability of water glass is improved. By simply drying it under relatively mild temperature conditions, a film with excellent water resistance, alkali resistance, etc. can be formed, and the adhesion of the topcoat paint is also improved, making it suitable as a base treatment agent for ceramic siding boards. It is possible to sufficiently satisfy all the characteristics required by the above. In particular, when water glass and a tetramethoxysilane oligomer are pre-condensed and used in combination with a synthetic resin emulsion having a carboxyl group, the curability is further improved, and various types of water resistance, warm water resistance, etc. can be obtained. The characteristics are more excellent.

When a synthetic resin emulsion obtained by using oligosoap as an emulsifier is used, the mixing stability with water glass is greatly improved and the blending ratio of water glass to the synthetic resin emulsion is increased to improve the permeability. It is possible to improve, the applicable range as a base treatment agent can be further expanded, and it can also be applied to high density base materials, dense base materials with low water content after curing, etc. Become.

[0045]

The present invention will be described below in more detail with reference to Reference Examples and Examples.

Reference Example 1 (Production of oligo soap) 100 g of isopropyl alcohol was charged into a flask equipped with a stirrer, a reflux condenser, a thermometer and a dropping funnel, and the temperature was adjusted to 80 ° C. 30 g of acrylic acid, 70 g of ethyl acrylate, 6 g of n-dotecil mercaptan and 2,
A mixture of 0.5 g of 2'-azobisisobutyronitrile was added dropwise over 3 hours, and the mixture was aged at the same temperature for 2 hours. After cooling until the internal temperature reached 30 ° C., 25 g of 25% ammonia water was added for neutralization to obtain a transparent solution having a nonvolatile content of 35% and pH 7. This product has an acid value of 220 and a molecular weight of 280.
It was 0.

Reference Example 2 (Production of Synthetic Resin Emulsion) In a flask equipped with a stirrer, a reflux condenser and a raw material inlet, 250 g of water and polyoxyethylene nonylphenyl ether sulfate sodium salt 2.5 as an emulsifier were used.
g, the internal temperature was kept at 75 ° C., ammonium persulfate 1.5 g was added, and then methyl methacrylate 90 g,
A mixture of 300 g of butyl acrylate, 100 g of styrene and 10 g of acrylic acid was added to 7.5 g of sodium polyoxyethylene nonylphenyl ether sulfate, 5 g of polyoxyethylene nonyl phenyl ether and 22 g of water.
The monomer emulsion obtained by emulsification with 5 g was added dropwise over 3 hours. After completion of the dropping, 5 g of a 10% ammonium persulfate aqueous solution was added to reduce residual monomers,
Aged at 2 ° C for 2 hours. Cooling the resulting emulsion,
While continuing stirring, 6.6 g of 25% aqueous ammonia was added as a neutralizing agent to obtain a milky white emulsion having a nonvolatile content of 50%. The obtained emulsion has a viscosity of 1500 cp
s, pH 8 and average particle size 0.18μ.

Reference Example 3 (Production of Synthetic Resin Emulsion) A flask equipped with a stirrer, a reflux condenser and a raw material inlet was charged with 250 g of water and 12 g of oligosoap of Reference Example 1 as an emulsifier, and the internal temperature was adjusted to 75 ° C. Hold and add 1.5 g of ammonium persulfate, then add methyl methacrylate 9
A monomer emulsion obtained by emulsifying a mixture of 0 g, 300 g of butyl acrylate, 100 g of styrene and 10 g of acrylic acid with 225 g of water in which 34 g of oligosoap of Reference Example 1 and 2.5 g of caustic soda were dissolved was added dropwise over 3 hours. After the dropping, 10 to reduce the residual monomer.
% Ammonium persulfate aqueous solution 5 g and added at 80 ° C for 2
After aging for a period of time, the mixture was cooled, and 2.5 g of 25% aqueous ammonia was added while continuing stirring to obtain a milky white emulsion having a nonvolatile content of 50%. The obtained emulsion has a viscosity of 1000.
cps, pH 7, average particle size 0.20μ.

Example 1 The synthetic resin emulsion having a carboxyl group obtained in Reference Example 2, water glass No. 3 (manufactured by Osaka Silica Co., Ltd.) and tetramethoxysilane oligomer (trade name: MS-51, Mitsubishi Chemical Corporation) ), The degree of polymerization 4 to 5) as a raw material, the components were mixed in the mixing ratios shown in Table 1 below, and the solid content was adjusted to 30% by weight with tap water to obtain a base treatment agent. . The obtained surface treating agent was a milky white emulsion having a pH of 11.0 ± 0.5 and a viscosity of 50 cp or less. Using this undercoating agent, the test for leaving stability and coating film performance was conducted by the following methods. The results are shown in Table 1 below.

In the coating film performance test, three types of ceramic siding boards, a silica cement board, a slag gypsum board and a wood wool cement board, were used as base materials, and a base treatment agent adjusted to a solid content of 30% by weight was used. 40 g of solid content by spraying
It was applied so as to have a coating amount of m ² and dried at 80 ° C. for 2 minutes, and then a commercially available gloss paint (acrylic-styrene-based water-based paint) as an overcoat paint was applied at 200 g / m ²
After being applied with a spray at the application amount of, the sample was dried and cured at room temperature for 7 days to obtain a test product.

<Testing Method> -Left Stability 100 g of the surface treatment agent was sampled in a 100 ml sample bottle, and the container was sealed and left at room temperature for 2 weeks, and evaluated visually.
Those in which separation and solidification did not occur are indicated by a circle.

・ Adhesiveness [0052] On the surface of the film, 25 goggles at a distance of 2 cm were inserted with a cutter knife until the base material was reached, and cellophane tape was adhered onto the base material and peeled off at a stretch to form a coating film on the surface of the base material. The number of remaining squares was calculated. The value of 25/25 means that the coating film is completely left on the substrate, and 0 /
25 means that the coating film is completely peeled off.

Warm Water Resistance Each test piece having a film formed thereon was immersed in warm water at 60 ° C. for 7 days and dried at 50 ° C. for 2 days, and then the adhesion was examined by the same method as the adhesion test.

· Topcoat adhesion Each film-formed test piece was immersed in warm water at 60 ° C for 7 days, and then visually observed for blisters (blisters) due to poor adhesion between the topcoat paint and the undercoating agent. ) Occurrence was confirmed. O marks indicate that there is no abnormal appearance and blisters are not confirmed, and x marks indicate that blisters have occurred.

Alkali resistance Each test piece having a film formed thereon was immersed in a 5% NaOH aqueous solution for 7 days and dried at 50 ° C. for 2 days, and then the adhesion was examined by the same method as the adhesion test.

Freezing damage resistance Each film-formed test piece was immersed in water at 30 ° C. for 8 hours,
A test of 50 cycles was carried out with 8 hours of freezing in water at 20 ° C. as one cycle. After drying at room temperature for 2 days, the adhesion was examined by the same method as described above. Example 2 In a flask equipped with a stirrer, a reflux condenser, a dropping funnel and a raw material inlet, water glass No. 3 (Osaka Silica Co., Ltd. ) Made 4
Charge 50 g and add 150 g of water to obtain a concentration of 37.5%
Of the tetramethoxysilane oligomer (trade name: MS-51, manufactured by Mitsubishi Chemical Corporation, polymerization degree 4 to 4) from the dropping funnel while maintaining the internal temperature at 50 ° C. and stirring.
5) Gradually add 25 g over 30 minutes to adjust the liquid temperature to 50
The temperature was maintained at 0 ° C. and stirring was continued, and the water glass and the tetramethoxysilane oligomer were condensed over 3 hours. Then, the mixture was cooled to room temperature and had a nonvolatile content of 40% by weight and a pH of 11.
A transparent aqueous solution having a viscosity of 500 cP was obtained.

To this transparent aqueous solution, the synthetic resin emulsion obtained in Reference Example 2 was blended so that the ratio of synthetic resin emulsion / transparent aqueous solution (solid content ratio) = 90/10, tap water was added, and the solid content was 30%. % By weight, pH 11.0, viscosity 10c
A milky white emulsion of P was obtained. Using this as an undercoating agent, tests for leaving stability and coating film performance were conducted in the same manner as in Example 1. The results are shown in Table 1 below.

Examples 3 to 5 and Comparative Examples 1 to 6 In the same manner as in Example 1, an undercoating agent was prepared with the compounding ratios shown in Tables 1 and 2 below, and the standing stability and coating film performance were tested. Was done. The results are shown in Tables 1 and 2 below.

In each example, as the synthetic resin emulsion, the one obtained in Reference Example 2 or Reference Example 3 was used, and as the tetramethoxysilane oligomer, the trade name: MS
-51 (Mitsubishi Chemical Corporation, degree of polymerization of tetramethoxysilane 4-5) or trade name: MS-56 (Mitsubishi Chemical Corporation,
An oligomer having a degree of polymerization of tetramethoxysilane of 8 to 10) is used, and the silane coupling agent is a trade name: A1.
87 (manufactured by Nippon Unicar Co., Ltd., chemical formula: CH ₂ CHCH ₂
A silane coupling agent of OC ₃ H ₆ Si (OCH ₃ ) ₃ ) was used, and water glass No. 1 or water glass No. 3 manufactured by Osaka Silica Co., Ltd. was used as the water glass.

In Comparative Example 3, the coating film could not be tested because it gelled during the preparation of the solution.

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[Table 1]

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[Table 2]

Claims (3)

[Claims] 1. An aqueous undercoating agent for a ceramic siding board, which comprises water glass, a tetramethoxysilane oligomer, and a synthetic resin emulsion having a carboxyl group. 2. The water-based base treating agent for a ceramic siding board according to claim 1, which contains water glass and a tetramethoxysilane oligomer in a condensed state with each other. 3. A synthetic resin emulsion obtained by emulsion-copolymerizing a vinyl monomer using a carboxyl group-containing synthetic resin emulsion as a water-soluble or water-dispersible polymer having a carboxyl group and / or a salt thereof as an emulsifier. The water-based undercoating agent for ceramic siding boards according to claim 1 or 2, which is an emulsion.