JP3294649B2 - Composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composition comprising a specific modified polyvinyl alcohol (A) and a specific aqueous emulsion (B), and more particularly to various industrial products such as a sealer composition for a porous inorganic plate. It relates to a composition effective as a material. Inorganic plates such as calcium silicate plate, gypsum board, lightweight cellular concrete (ALC) plate and rock wool board are all porous, and therefore have low surface layer strength and easily absorb moisture. As a result, if the surface is finished as it is, the powder on the surface layer will not mix with the finishing material and will not be finished beautifully, the bleeding of the acne from the inorganic plate, or even if it is finished well, will be immediately peeled off, or will freeze if water or moisture is absorbed. There is a problem in terms of aesthetics and its durability, such as the finish material peeling off due to repeated melting. In order to prevent such troubles, a sealer is applied to the surface of such an inorganic plate before finishing it.
The application of the sealer may be performed at a factory inorganic plate production line or at the time of a finishing treatment at a building site. The present invention is a composition particularly effective when performing a sealer treatment at a factory inorganic plate production line. It is about things.

[0002]

2. Description of the Related Art A sealer-treated inorganic plate is left as a commercial product for several months in that state, or is subjected to rainwater, outside air for several months before being provided for construction and finished with makeup. May be exposed.
Therefore, the characteristics required for such a sealer can be broadly classified into three: a reinforcing effect on the surface layer of the inorganic plate, a water stopping performance, and adhesion to the finishing material. Conventionally, solvent-based sealers such as urethane resin, epoxy resin, and vinyl chloride resin have been mainly used, and a typical example thereof is a moisture-curable urethane resin-based sealer.

[0003] This has good surface layer reinforcing effect and good water stopping performance, but if left for a long period of time while being treated with a sealer, the coating film will harden too much and the adhesion to the initially good finishing agent will decrease. In addition to the problem that the solvent is used, there are safety and health problems due to the solvent system. In addition, since the solvent used as the diluent is expensive and a mixed solvent, there is a problem that the cost is unavoidable even in consideration of recovery and reuse.

On the other hand, a typical water-based sealer is mainly composed of an acrylic emulsion using a low molecular surfactant as a dispersant. Although this has the advantage of not using a solvent at all, the effect of reinforcing the surface layer of the inorganic plate is extremely small, so there is no problem for a while if it is finished, but after a few months, peeling occurs on the surface layer of the inorganic plate. There is a problem that it cannot be used stably. Also regarding the water stop performance,
Despite being inherently a hydrophobic resin, it is difficult to obtain a satisfactory resin. The reason is that the thickener used in combination lowers the water resistance of the coating film, and defects during coating are more likely to occur than in the solvent-based sealer. In other words, relatively large pores are scattered in the surface layer of the porous inorganic plate, and when the sealer liquid is applied, it penetrates intensively into the portion, so that it is difficult to form a uniform coating liquid film, and before drying. It is thought that there is a hole.

As a method for improving the disadvantages of such an aqueous sealer, there has been proposed a method in which polyvinyl alcohol (hereinafter abbreviated as PVA) and an aqueous emulsion are used in combination (see JP-A-53-97018). . However, even in this method, the reinforcing effect of the inorganic plate and the water stopping performance described above are not sufficiently improved. Further, an aqueous sealer comprising a modified PVA having a silyl group in the molecule (see JP-A-58-167485) or an aqueous sealer comprising a synthetic resin emulsion containing the modified PVA having a silyl group in the molecule as an emulsifier See, for example, JP-A-58-171457). These water-based sealers are remarkably improved in terms of the effect of reinforcing the surface layer of the inorganic plate or the adhesion to the inorganic plate as compared with conventional water-based sealers, and are excellent in that respect. When it is not sufficient, and when the surface decorative finishing material is an acrylic paint, there is a problem that the adhesion to the finishing agent may be low.

Further, in order to solve such a problem, an aqueous sealer containing an epoxy-based emulsion as a main component has been proposed. There is a limitation on the working time, which has a serious problem in practical use. In addition, (1)
PVA (A) having 0.01 to 5 mol% of silyl group and acrylic emulsion (glass transition temperature 5 to 50 ° C) (B)
And a solid content ratio (A) / (B) based on weight.
= Sealant composition for a porous inorganic plate having a ratio of 5/95 to 50/50 (see JP-A-62-161878),
(2) PVA (A) having a silyl group in an amount of 0.01 to 5 mol%
And acrylic emulsion (glass transition temperature 5-50 ° C)
(B) and a water-proofing agent (C), and a solid content ratio (A) / (B) = 5/95 to 50/50 on a weight basis.
Sealer composition for a porous inorganic plate wherein (A) / (C) = 99.5 / 0.5 to 10/90 (JP-A-63-13908)
No. 3), (3) PVA (A) having a silyl group in an amount of 0.01 to 5 mol% and an acrylic emulsion (glass transition temperature of more than 50 ° C. and 120 ° C. or less) (B), and solid on a weight basis Mixing ratio (A) / (B) = 5 / 95-
A 50/50 sealer composition for a porous inorganic plate, a sealer composition prepared by using a waterproofing agent (C) in combination therewith (see JP-A-64-14182), and (4) a silyl group having 0 or less. Porous inorganic plate composed of PVA (A) having 0.01 to 5 mol% and polyvinyl acetate emulsion (B), and having a solid content ratio (A) / (B) = 5/95 to 50/50 on a weight basis Sealer compositions for use, and water-proofing agents (C) added thereto (A) / (C) = 99.5 / 0.5 to 10/9
A sealer composition used in combination at a ratio of 0
No. 139082) is known. All of these sealer compositions have excellent performance, but there is still a need for a higher performance sealer in terms of the effect of reinforcing the surface layer and the adhesion to the water-stop finishing material.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a water system having no problem in terms of safety and hygiene, and it is difficult for coating defects to occur even in the case of a single application, and the surface layer reinforcing effect and the water stopping performance are reduced. An object of the present invention is to provide a composition which is comparable to a solvent-based sealer and which does not deteriorate in adhesion to a finish even when left for a long time while being treated with a sealer. Another object of the present invention is to apply a sealer to a plate having a high water content, and to simultaneously perform the drying of the plate and the sealer. The object of the present invention is to provide a composition which is comparable to a solvent-based sealer and in which the adhesion to a finishing material does not decrease even if the sealer is left for a long time. Still another object of the present invention is that coating defects are less likely to occur even in the case of a single application, the surface reinforcing effect, the water stopping performance and the adhesion to the finishing material are further improved, and the conventional sealer composition An object of the present invention is to provide a composition which can cope with a difficult high-density porous inorganic plate.

The present inventors have made intensive studies to overcome the various disadvantages of the prior art and achieve the above object. As a result, a modified polyvinyl alcohol containing a silyl group in the molecule, and a dispersoid of an acrylate type or a methacrylate type (hereinafter, an acrylate or a methacrylate is referred to as a “(meth) acrylate”) ), A homopolymer or a copolymer composed of one or more monomers selected from styrene-based and diene-based monomers (hereinafter, homopolymers and copolymers are referred to as “(co)
Polymer ". ) Wherein the dispersant is a composition mainly comprising an aqueous emulsion which is a polyvinyl alcohol polymer having a mercapto group at a terminal; and
It has been found that a composition to which a water-proofing agent is further added has physical properties suitable for the above purpose. The present invention has been completed based on such findings.

That is, the present invention provides a method for forming a silyl group in a molecule.
Modified polyvinyl alcohol (A) having 0.01 to 5 mol% and at least one dispersoid selected from (meth) acrylate ester monomer units, styrene monomer units and diene monomer units Including monomer units (co)
Aqueous emulsion (B), which is a polymer and the dispersing agent is a polyvinyl alcohol-based polymer having a mercapto group at a terminal, and a solid content ratio (A) /
(B) 5/95 to 50/50. A composition comprising the above component (A) and a water-resistant agent (C) added thereto. Is also provided.

The modified polyvinyl alcohol (modified PVA), which is the component (A) of the composition of the present invention, may be any as long as it contains a silyl group in the molecule. Those having a reactive substituent such as a group, an acyloxyl group or a silanol group which is a hydrolyzate thereof or a salt thereof are particularly preferably used. As a method for producing such a modified PVA,
A method for introducing a silyl group into PVA or a modified polyvinyl acetate containing a carboxyl group or a hydroxyl group by post-modifying with a silylating agent, and a method for copolymerizing a vinyl ester with a silyl group-containing olefinically unsaturated monomer. Examples of the method include a method of saponifying the union and a method of saponifying a polyvinyl ester having a silyl group at a terminal obtained by polymerizing a vinyl ester in the presence of a mercaptan having a silyl group.

In the above method, for example, the silylating agent is dissolved in an organic solvent (such as benzene, toluene, xylene, hexane, heptane, ether or acetone) which does not react with the silylating agent, and the resulting solution is added to the solution. The powdered PVA or the modified polyvinyl acetate is suspended with stirring, and the reaction between the silylating agent and PVA or the modified polyvinyl acetate is carried out at room temperature to a temperature in the range of the boiling point of the silylating agent, or further, by alkali reaction. By hydrolyzing the vinyl acetate unit with a catalyst or the like, a silyl group-containing modified PVA can be obtained.

The silylating agent used in the post-modification includes organohalogenosilanes such as trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, vinyltrichlorosilane, diphenyldichlorosilane and triethylfluorofuran, trimethylacetoxysilane and dimethyldiacetoxysilane. And the like; organosilyl esters such as trimethylmethoxysilane and dimethyldimethoxysilane; organosilanols such as trimethylsilanol and diethylsilanediol; aminoalkylsilanes such as N-aminoethylaminopropyltrimethoxysilane; trimethylsilylisoanate; And organosilyl isoanates. The introduction rate of the silylating agent, that is, the degree of modification can be arbitrarily adjusted depending on the amount of the silylating agent used and the reaction time. Also obtained silyl group-containing modified PV
The degree of polymerization and saponification of A are the degree of polymerization of PVA used,
The degree of saponification or the degree of polymerization of the modified polyvinyl acetate and the saponification reaction can be arbitrarily adjusted.

In the above method, ie, a method of saponifying a copolymer of a vinyl ester and a silyl group-containing olefinically unsaturated monomer, for example, a vinyl ester and a silyl group-containing olefinically unsaturated monomer in an alcohol are used. The monomer is copolymerized with a radical initiator, and then an alkali or acid catalyst is added to an alcohol solution of the obtained copolymer, and the copolymer is saponified to obtain a desired silyl group-containing polymer. Modified PVA can be obtained. Examples of the vinyl ester used in this method include vinyl acetate, vinyl propionate, vinyl formate and the like, but vinyl acetate is preferred for practical use. Examples of the silyl group-containing olefinically unsaturated monomer used in the above method include vinylsilane represented by the following formula (I) and (meth) acrylamide-alkylsilane represented by the following formula (II).

[0014]

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Wherein n is an integer of 0 to 4, m is an integer of 0 to 2, R ¹ is an alkyl group having 1 to 5 carbon atoms (such as methyl and ethyl), and R ² is an alkoxyl group having 1 to 40 carbon atoms. A group or an acyloxyl group (the alkoxyl group and the acyloxyl group may have a substituent containing oxygen), R ³ is a hydrogen atom or a methyl group, R ⁴ is a hydrogen atom or a C 1-5 Alkyl group, R ⁵ has 1 to ⁵ carbon atoms
Represents a divalent organic residue in which alkylene groups or chain carbon atoms are mutually bonded by oxygen or nitrogen. When R ¹ has two or more in the same monomer, each R ¹ may be the same or different. Also, when two or more R ² are present in the same monomer, each R ² may be the same or different. Specific examples of the vinylsilane represented by the formula (I) include, for example, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris- (β-methoxyethoxy) silane, vinyltriacetoxysilane, allyltrimethoxysilane, allyltriacetoxysilane , Vinylmethyldimethoxysilane, vinyldimethylmethoxysilane, vinylmethyldiethoxysilane, vinyldimethylethoxysilane, vinylmethyldiacetoxysilane, vinyldimethylacetoxysilane, vinylisobutyldimethoxysilane, vinyltriisopropoxysilane, vinyltributoxysilane, vinyl Trihexyloxysilane, vinylmethoxydihexyloxysilane, vinyltrioctyloxysilane, vinyldimethoxyoctyloxysilane, vinylmethoxydioctyl Kishishiran, vinyl methoxy dilaurate Lilo silane, vinyl dimethoxy Lau Lilo silane, vinyl methoxy geo Ray B silanes, vinyl dimethoxy I acetoxyphenyl silane, more general formula

[0016]

Embedded image

[Where R ¹ and m are the same as above, and x is 1 to
Indicates an integer of 20. And the like. Specific examples of the (meth) acrylamide-alkylsilane represented by the formula (II) include 3- (meth) acrylamide-propyltrimethoxysilane and 3- (meth) acrylamide-
Propyltriethoxysilane, 3- (meth) acrylamido-propyltri (β-methoxyethoxy) silane,
2- (meth) acrylamido-2-methylpropyltrimethoxysilane, 2- (meth) acrylamido-2-methylethyltrimethoxysilane, N- (2- (meth) acrylamido-ethyl) -aminopropyltrimethoxysilane, 3 -(Meth) acrylamido-propyltriacetoxysilane, 2- (meth) acrylamido-ethyltrimethoxysilane, 1- (meth) acrylamido-methyltrimethoxysilane, 3- (meth) acrylamido-propylmethyldimethoxysilane, 3- ( (Meth) acrylamide-propyldimethylmethoxysilane, 3-
(N-methyl- (meth) acrylamido) propyltrimethoxysilane, 3-((meth) acrylamido-methoxy) -3-hydroxypropyltrimethoxysilane, 3-((meth) acrylamido-methoxy) -propyltrimethoxysilane; N, N-dimethyl-N-trimethoxysilylpropyl-3- (meth) acrylamido-propylammonium chloride; N, N-dimethyl-N-trimethoxysilylpropyl-2- (meth) acrylamido-2-methylpropylammonium chloride And the like.

In the above-mentioned method, when the vinyl ester and the silyl group-containing olefinically unsaturated monomer are copolymerized, another unsaturated monomer copolymerizable with the monomer other than the above two components is used. Monomers such as styrene, alkyl vinyl ether, vinyl versatate, (meth) acrylamide, or olefins such as ethylene, propylene, α-hexene, α-octene, (meth) acrylic acid, crotonic acid, (maleic anhydride), and fumaric acid. Unsaturated acids such as acid, itaconic acid and the like, alkyl esters and alkali (earth) metal salts thereof, sulfonic acid-containing monomers such as 2-acrylamido-2-methylpropanesulfonic acid and alkali (earth) metal salts thereof, Trimethyl-3- (1- (meth) acrylamide-1,1-dimethylpropyl) ammonium chloride, It is also possible to use a small amount of a cationic monomer such as methyl-3- (1- (meth) acrylamidopropyl) ammonium chloride, 1-vinyl-2-methylimidazole and a quaternary compound thereof.

Further, in the above-mentioned method, that is, in the method of saponifying a polyvinyl ester having a silyl group at a terminal obtained by polymerizing a vinyl ester in the presence of a mercaptan having a silyl group, the following operation is performed. . For example, when polymerizing a vinyl ester using a radical initiator, a mercaptan having a silyl group is added to the polymerization system all at once or dividedly or continuously,
After a mercaptan having a silyl group is present in the polymerization system, and a polyvinyl ester having a silyl group at a terminal is generated by chain transfer to the mercaptan, an alkali or acid catalyst is added to an alcohol solution of the polyvinyl ester, and the polyvinyl By saponifying the ester, a modified PVA having a desired silyl group can be obtained. Examples of the mercaptan having a silyl group used in this method include 3- (trimethoxysilyl) -propylmercaptan and 3- (triethoxysilyl) -propylmercaptan. In producing a modified PVA having a silyl group by this method, a small amount of an unsaturated monomer copolymerizable with the vinyl ester used in the above method can be present.

As described above, modified P containing a silyl group in the molecule
Although the method for producing VA has been described in detail, the method based on copolymerization (that is, the method) is more preferable than the method based on post-modification in terms of easiness of industrial production. Further, among the methods for producing modified PVA by copolymerization, a saponified copolymer of a silyl group-containing olefinically unsaturated monomer represented by the formula (I) and a vinyl ester, produced according to the method, It is excellent in viscosity stability of an aqueous solution, stability against alkali when an alkaline aqueous solution is used, or water resistance when formed into a film, and is preferably used. The above three methods (method ~)
The degree of modification of the modified PVA obtained by
The silyl group content in A is 0.01 to 5 mol%, preferably 0.1 to 5 mol%, as a monomer unit containing a silyl group in the molecule.
It is 1.0 mol%, more preferably 0.1 to 0.6 mol%.

When the content of the silyl group in the modified PVA is less than 0.01 mol%, the effect of reinforcing the surface layer of the inorganic plate is lost.
On the other hand, when the content exceeds 5 mol%, the stability of the aqueous emulsion as the component (B) used in combination becomes poor, so that the water-stopping property or the adhesion to the finishing material is unfavorably reduced. In order to cause pseudo-aggregation of an aqueous emulsion such as an acrylic emulsion as described below,
0.1 to 1.0 mol%, more preferably 0.1 to 0.6 mol%
It is. The degree of polymerization of the modified PVA (both post-modified PVA and modified PVA by copolymerization) is not particularly limited, and may be appropriately determined according to various situations.
3000, preferably 300-2000. The degree of saponification is not particularly limited, but is generally 70 to
It is selected from the range of 100 mol%. The silyl group-containing modified PVA thus obtained is dispersed in water, optionally added with a small amount of an alkali such as sodium hydroxide, potassium hydroxide, ammonium hydroxide, or an amine, and humidified while stirring. A uniform aqueous solution can be obtained.

On the other hand, the component (B) in the composition of the present invention
The aqueous emulsion is a (co) polymer whose dispersoid consists of at least one monomer selected from (meth) acrylates, styrenes and dienes (that is, these monomer units are (Including (co) polymer)
It is necessary that the dispersant is an aqueous emulsion which is a polyvinyl alcohol-based polymer having a mercapto group at a terminal. The (meth) acrylate monomers in the aqueous emulsion of the present invention include methyl (meth) acrylate, ethyl (meth) acrylate,
Butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, dodecyl (meth) acrylate, (meth)
Examples include 2-hydroxyethyl acrylate, dimethylaminoethyl (meth) acrylate and quaternized products thereof, and glycidyl methacrylate.

As the styrene monomer, styrene, α
-Methylstyrene, p-methylstyrenesulfonic acid, sodium and potassium salts, and the like, and diene monomers include butadiene, isoprene, and chloroprene. In the aqueous emulsion of the present invention, monomers other than (meth) acrylate, styrene and diene monomers can be copolymerized as long as the performance is not impaired. As copolymerizable monomers,
Olefins such as ethylene, propylene, isobutylene,
Vinyl esters such as vinyl formate, vinyl acetate, vinyl propionate and vinyl versatate; halogenated olefins such as vinyl chloride, vinyl fluoride, vinylidene chloride and vinylidene fluoride; acrylic acid, methacrylic acid, itaconic acid, crotonic acid, fumaric acid Α, β-ethylenically unsaturated carboxylic acids such as acid, maleic acid and citraconic acid and salts thereof, (meth) acrylamide, N-methylolacrylamide, N, N′-dimethylacrylamide, acrylamide 2-methylpropanesulfonic acid and the like Examples thereof include (meth) acrylamide monomers such as sodium salts, and other monomers such as vinylpyridine and N-vinylpyrrolidone.

In the aqueous emulsion of the present invention, the dispersant comprises
Polyvinyl alcohol having a mercapto group at the terminal (P
VA) -based polymer, preferably emulsifying (co-polymerizing) one or more monomers selected from the above (meth) acrylates, styrene-based and diene-based monomers in the presence of the PVA-based polymer. ) An aqueous emulsion obtained by polymerization. The PVA-based polymer having a mercapto group is represented by P
A polymer having a mercapto group in the main chain of the VA molecule has a sufficient effect. However, in this case, a disulfide bond may be formed by oxidation of PVA itself, which may cause insolubilization. A PVA polymer having a group is particularly desirable because it is easy to handle without fear of insolubilization.

Such a PVA polymer having a mercapto group at only one end of the molecule is a polyvinyl ester polymer obtained by polymerizing a vinyl monomer mainly composed of a vinyl ester monomer in the presence of thiolic acid. It is obtained by saponification by a conventional method, and this production method will be described in detail below. First, the thiolic acid used here is -COSH
And organic thiolic acids having groups. For example, thiol acetic acid, thiol propionic acid, thiol butyric acid, thiol valeric acid and the like can be mentioned. Among them, thiol acetic acid is most preferable because it has good decomposability. As the vinyl ester, any vinyl ester capable of radical polymerization can be used. For example, vinyl formate, vinyl acetate, vinyl propionate, vinyl versatate, vinyl laurate, vinyl stearate and the like can be mentioned. Among them, vinyl acetate is the most polymerizable and is preferred. Further, copolymerization can be carried out in the presence of a monomer copolymerizable with these vinyl esters. For example, ethylene, propylene, isobutylene, acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid or a salt thereof, or an alkyl ester, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, trimethyl- (3-acrylamide-3) -Dimethylpropyl) -ammonium chloride, ethyl vinyl ether, butyl vinyl ether, N
-Vinylpyrrolidone, vinyl chloride, vinyl bromide, vinyl fluoride, vinylidene chloride, vinylidene fluoride, tetrafluoroethylene, sodium vinyl sulfonate, sodium allyl sulfonate and the like.

The polymerization of vinyl monomers mainly composed of vinyl esters such as vinyl acetate in the presence of thiolic acid can be performed by any of bulk polymerization, solution polymerization, pearl polymerization, and emulsion polymerization in the presence of a radical polymerization initiator. The solution polymerization method using methanol as a solvent is industrially most advantageous. The amount and method of addition of thiolic acid to the polymerization system during the polymerization are not particularly limited, and should be appropriately determined according to the physical properties of the target polyvinyl ester polymer. As the polymerization system, a known system such as a batch system, a semi-continuous system, and a continuous system can be employed. As the radical polymerization initiator, known radical polymerization initiators such as 2,2′-azobisisobutyronitrile, benzoyl peroxide, and carbonate carbonate can be used.
An azo initiator such as 2,2'-azobisisobutyronitrile is preferred because it is easy to handle. Radiation, electron beams, etc. can also be used. It is desirable to employ an appropriate polymerization temperature depending on the type of the initiator used.
It is selected from the range of 0 to 90 ° C. After polymerizing for a predetermined time,
By removing the unpolymerized vinyl esters by a usual method, a polyvinyl ester polymer having a thiolate group at a terminal can be obtained.

The polyvinyl ester-based polymer thus obtained is saponified by a conventional method, but it is usually advantageous to carry out the polymer as an alcohol solution, especially a methanol solution. As the alcohol, not only an anhydride but also a small amount of a water-containing alcohol may be used according to the purpose, and an organic solvent such as methyl acetate or ethyl acetate may be arbitrarily contained. The saponification temperature is usually selected from the range of 10 to 70 ° C. As the saponification catalyst, an alkaline catalyst such as sodium hydroxide, potassium hydroxide, sodium methylate, potassium methylate and the like is preferable. The amount of the catalyst used is appropriately determined depending on the degree of saponification, the amount of water, and the like. The molar ratio is preferably 0.001 or more, and more preferably 0.002 or more. On the other hand, if the amount of alkali is too large, it is difficult to remove the remaining alkali from the polymer, which is undesirable because the polymer is colored, and the molar ratio is desirably 0.2 or less. In addition, when a component which consumes alkali and reacts with an alkali catalyst such as a carboxyl group or its ester group in the polyvinyl ester-based polymer is copolymerized, the amount of the alkali catalyst to be added should be used. .

The saponification reaction saponifies the terminal thiolate ester and the main chain vinyl ester bond of the polyvinyl ester polymer having a thiolate ester group at the terminal, and the polymer terminal is a mercapto group and the main chain is a vinyl alcohol. However, the degree of saponification of the vinyl ester unit in the main chain can be changed according to the purpose of use. After the saponification reaction, the precipitated polymer is purified by a known method such as washing with methanol to remove impurities such as residual alkali and alkali metal salts of acetic acid. Although the method for producing a PVA-based polymer having a mercapto group at the terminal used in the present invention has been described above, the degree of polymerization of this PVA-based polymer is preferably 3500 or less. The degree of saponification varies depending on the type of the other modifying group and cannot be unambiguously determined, but is preferably 70 mol% or more from the viewpoint of water solubility.

The amount of the PVA polymer thus obtained is from 1 to 20 with respect to the amount of the above (meth) acrylate, styrene, diene and other monomers.
% By weight, especially 2 to 10% by weight, is preferred. If the amount of the PVA-based polymer is less than 1% by weight based on the amount of the monomer, the emulsion polymerization stability is reduced, and it is difficult to obtain a stable aqueous emulsion. On the other hand, when the use amount of the PVA-based polymer exceeds 20% by weight, there may be a problem that the sealant composition does not sufficiently exhibit water-stopping performance and adhesion to the finishing material.

Using the PVA-based polymer as a dispersant,
In carrying out the emulsion (co) polymerization of one or more monomers selected from (meth) acrylates, styrene-based and diene-based monomers, the emulsification (co) polymerization is carried out in the presence of water, a dispersant and a polymerization initiator. Any ordinary emulsion polymerization method in which an unsaturated monomer is added temporarily or continuously, followed by heating and stirring can be carried out, or the unsaturated monomer can be previously mixed and emulsified with a PVA-based polymer aqueous solution. A method of continuously adding the mixture may also be implemented. As the polymerization initiator, a redox system using a mercapto group at the terminal of PVA and a water-soluble oxidizing agent such as potassium bromate, potassium persulfate, and hydrogen peroxide is also possible. Among them, potassium bromate is used under ordinary polymerization conditions. A single radical does not generate a radical, but is decomposed only by a redox reaction with a mercapto group at the end of PVA, and generates a radical. Thus, PVA and a block copolymer are effectively generated, and thus the stabilizing effect is increased. Are particularly preferred initiators. It is also possible to use an oxidizing agent in combination, for example, by adding potassium bromate at the start of the polymerization and then adding another oxidizing agent.

In carrying out the emulsion (co) polymerization using a dispersant comprising a PVA-based polymer having a mercapto group at the terminal in the present invention, it is important and desirable that the polymerization system is acidic. This is because, under basic conditions, the mercapto group, which exhibits extremely active reactivity in radical polymerization, has a high rate of ionic addition and disappearance to the double bond of the monomer, and the polymerization efficiency is significantly reduced. , Depending on the type of unsaturated monomer,
It is preferably carried out at H6 or lower, preferably at pH 4 or lower. In the present invention, P having a mercapto group
It is preferable that the dispersant composed of the VA polymer is used alone as described above. However, if necessary, a conventionally known anionic, nonionic, cationic surfactant or water-soluble polymer may impair the performance. It can be used together as appropriate within the range not present.

Various aqueous emulsions can be added to the aqueous emulsion (B) of the present invention, if necessary. Such aqueous emulsions include polyvinyl acetate emulsion, ethylene-vinyl acetate copolymer emulsion, polychloroprene emulsion, polybutadiene emulsion, styrene-butadiene copolymer emulsion, butadiene-acrylonitrile copolymer emulsion, butyl rubber emulsion, and polyacrylate. Emulsions, polyvinyl chloride emulsions, polyvinylidene chloride emulsions, and the like.

The composition of the present invention basically comprises the component (A)
And a component (B) as a main component, and if necessary, a water-proofing agent (C) of the component (A) can be blended. Here, as the water-proofing agent which is the component (C),
Colloidal silica, water glass, borax, a water-dispersible isocyanate compound, polyamide resin, melamine resin, polyamide methylol resin, polyethylene imide, etc. are used, and among them, colloidal silica or a water-dispersible isocyanate compound is preferable. Here, as the water-dispersible isocyanate compound, water-emulsifiable methylenebisdiphenylisocyanate (water-emulsifiable MDI) (for example, manufactured by Nippon Polyurethane Co., Ltd., trade name: Coronate C-3053)
And water-emulsifiable blocked urethane prepolymer (for example, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name: Elastron E)
-37) and the like. In addition, tolylene diisocyanate (TD
I); hydrogenated TDI; trimethylolpropane-TDI
Adduct (for example, manufactured by Bayer AG, trade name: Desmo
dur L); triphenylmethane triisocyanate; methylenebisdiphenyl isocyanate (MD
I); hydrogenated MDI; polymerized MDI; hexamethylene diisocyanate; xylylene diisocyanate;
Dicyclohexylmethane diisocyanate; those obtained by forcibly emulsifying isophorone diisocyanate in the presence of a suitable emulsifier.

As described above, the composition of the present invention comprises the component (A) and the component (B) as main components, and the solid content weight ratio (A) / (B) is 5/95. ~ 50 /
It should be in the range of 50, preferably 7/9
It is in the range of 3 to 40/60. When the water content of the inorganic plate to be applied is 20% by weight or more, the composition of the present invention comprises:
It is preferable that the component (C) is the main component together with the components (A) and (B). In this case, the solid content weight ratio of each component is such that (A) / (B) is 5/95 to 50/50. , (A) /
(C) is preferably in the range of 99.5 / 0.5 to 10/90, and particularly (A) / (B) is preferably in the range of 7/93 to 40/6.
0, (A) / (C) is optimally in the range of 99/1 to 50/50. In the case of a high-density porous inorganic plate, the component (C) is preferably a water-dispersible isocyanate compound, and (A) / (B) may be 5/95 to 50/50,
(A) / (C) is preferably in the range of 99/1 to 50/50.

The composition of the present invention comprises the components (A) and (B) and, if necessary, the component (C) as described above, but the method of blending these components is not particularly limited. There is no. As a compounding method, for example, an aqueous solution of a silyl group-containing modified PVA as a component (A) is mixed with stirring in an aqueous emulsion as a component (B), and if necessary, a water-proofing agent as a component (C) well to mix Finally, component (C) is preferably mixed immediately before coating the inorganic board as sealer. In the composition of the present invention, in addition to the above-mentioned components, inorganic pigments such as calcium carbonate, clay, titanium oxide, zinc oxide and red iron oxide, urea as a coating liquid stabilizer, and an antifoaming agent are dispersed and mixed. May be. Further, it can be used by diluting with water at the end so that a coating liquid having an appropriate viscosity can be obtained. The coating solution concentration is usually 10
６０60% (solid content), preferably 20-40% (solid content).

Although the composition of the present invention is used for various uses, it is particularly suitable as a sealer for a porous inorganic plate.
When the composition of the present invention is used as a sealer, examples of the porous inorganic plate to be applied include those mainly composed of an inorganic material such as cement, calcium silicate, gypsum, sand and clay mineral. Specific examples include lightweight concrete, precast concrete, lightweight cellular concrete (ALC), mortar, asbestos cement board, calcium silicate board, pulp cement board, wood wool cement board, gypsum board, and hard board. Although these inorganic plates may contain an organic component, the composition of the present invention is particularly suitable for a porous inorganic plate mainly containing an inorganic component composed of a compound such as Si, Ca, Mg, or Al. It is suitable. As a method of applying to the inorganic plate, any of general coating methods such as spray coating, roller coating, flow coater, and dipping can be used. Application amount is as dry solids
0.5 to 100 g / m ² is preferred. It is more effective to heat and dry at 100 ° C. or more after applying the composition of the present invention.

The composition of the present invention, while being water-based, hardly causes coating defects, has a surface layer reinforcing effect comparable to that of a solvent-based sealer, water stopping performance, moisture resistance and hot water resistance in a single application, and It is extremely useful as an industrial material in which excellent adhesion to the finishing material can be obtained even after being left for a long time after the sealer treatment.

[0038]

EXAMPLES The present invention will now be described specifically with reference to examples, but these examples do not limit the present invention at all. All parts or percentages are by weight unless otherwise specified. In addition, the test method in an Example is as follows.

(1) Water permeability test This is a test for measuring the water stopping performance of a sealer. The composition of the present invention is applied to various porous inorganic plates at a solid content of 20 g / m ^2.
Apply and dry at 150 ° C for 20 minutes, 20 ° C, 65% R
It was left for 7 days under H (relative humidity) conditions. The open end of the triangle funnel was fixed to the surface of this test piece with an epoxy-based adhesive so as not to leak water. A burette was connected to the end, and water was added so that the initial head was 25 cm. I read. The smaller the value, the better the water stopping performance.

(2) Adhesion test A test for measuring the reinforcing effect of the surface layer of the porous inorganic plate by the sealer and the adhesion between the surface layer of the inorganic plate and the finish coating agent. The sealer was applied by the method of (1). Solvent-type acrylic resin paint (Toa Paint Co., Ltd., acrylic D
X, white), and before the solvent-type acrylic resin coating had dried, a cotton cloth was placed thereon, and the coating was dried at room temperature for 2 days. Thereafter, a cut was made with a knife to a width of 1 cm, the peeling resistance was measured at an peeling angle of 90 ° and a pulling speed of 50 mm / min using an autograph (manufactured by Shimadzu Corporation, Model IM-100), and the peeling state was observed. That is, those having poor adhesion to the top coat are peeled off at the interface between the sealer application surface and the top coat. In addition, those having a large reinforcing effect on the surface layer of the inorganic plate have a large peeling resistance, and many broken pieces of the inorganic plate adhere to the peeled surface.

(3) Weathering Test In some cases, inorganic plates such as building materials are left for several months or more before being subjected to decorative finishing after being treated with a sealer. In this case, the sealer-treated plate used for construction is exposed to sunlight, rain, and wind. If the exposed surface of the sealer becomes rough or discolored due to such exposure, it may hinder the cosmetic finish. Also, the adhesion to the decorative finishing material changes. The weathering test is a test for measuring the weather resistance due to such outdoor exposure.
Xenon lamp (XW-60 manufactured by Shimadzu Corporation) at 40 ° C
(V ₃ , 6 kW) Irradiation for 200 hours and water spraying for 18 minutes every 2 hours were performed, and changes in the treated surface of the sealer were examined. In addition, the sample after irradiation was coated with a topcoat paint and examined for adhesion.

(4) Marlon Mechanical Stability Test This is a test for measuring the stability of the liquid at the time of coating the sealer. The test was performed using a Marlon tester (Maro, manufactured by Shinsei Sangyo Co., Ltd.).
N, 1000 rpm), load 25k on 50g of coating liquid
g, applying a shearing force at 1000 rpm for 10 minutes to generate a gelled substance (the gelled substance is separated and dried with a 100-mesh wire net and expressed in terms of% by weight based on the solid content of 50 g of the coating liquid).
Checked.

(5) Warm water resistance test The composition of the present invention was added to a porous inorganic plate at a solid content of 20 g / m2.
^{2 was} applied and dried at 150 ° C. for 20 minutes, and then a solvent-type acrylic resin paint (Toa Paint Co., Ltd., acrylic DX for toile tile, white) was applied and dried at room temperature for 2 days. The coated product was immersed in warm water at 50 ° C. for two consecutive weeks, and the blisters of the overcoat were observed.

(6) Hot water test The composition of the present invention was added to a porous inorganic plate at a solid content of 20 g / m2.
^{2 was} applied and dried at 150 ° C. for 20 minutes, and then a solvent-type acrylic resin paint (Toa Paint Co., Ltd., acrylic DX for toile tile, white) was applied and dried at room temperature for 2 days. The coated product was immersed in hot water of 80 ° C. for 2 hours, and the blister of the top coating was observed.

Example 1 A copolymer of vinyltrimethoxysilane and vinyl acetate was saponified to contain 0.5 mol% of a silyl group as a vinyl silane unit, a saponification degree of the vinyl acetate unit of 98.5 mol%,
Modified PVA containing a silyl group in the molecule having a polymerization degree of 500
I got This modified PVA was dissolved in water to prepare a 15% aqueous solution. On the other hand, in a 1-liter glass container equipped with a reflux condenser, a dropping funnel, a thermometer, and a nitrogen inlet, PVA having a mercapto group at the end (PVA-1;
(0, saponification degree: 88.5 mol%)
The mixture was dissolved by heating in 0 g, and adjusted to pH = 3.5 with dilute sulfuric acid.
Next, 55 g of methyl methacrylate and 45 g of butyl acrylate were charged while stirring at 140 rpm, and
After the temperature was raised, 10 g of a 5% aqueous solution of ammonium persulfate was added to initiate polymerization. 15 minutes after starting the polymerization,
110 g of methyl methacrylate, 90 butyl acrylate
g, 5 g of 2-hydroxyethyl methacrylate were added continuously over 2 hours. After 5 hours, 99.9% conversion
And cooled. The resulting emulsion was adjusted to pH = 6.8 with aqueous ammonia, and had a solid content of 51.0% and a viscosity of 9%.
An aqueous emulsion (I) of 50 cp was obtained. To 100 parts of the aqueous emulsion (I), 85 parts of a previously prepared 15% aqueous solution of modified PVA was mixed with stirring, and correction water was added thereto to prepare a 25% concentration sealer composition (modified PVA and aqueous emulsion (I)). With a solid content of 20/80). A calcium silicate plate (absolute dry specific gravity 0.8)
5, water content 7%) to evaluate the performance. Table 1 shows the results.

Comparative Example 1 The procedure of Example 1 was repeated, except that only the modified PVA aqueous solution was used instead of the sealer composition of Example 1. The results are shown in Table 1.

Comparative Example 2 The procedure of Example 1 was repeated, except that the aqueous emulsion (I) was adjusted to a concentration of 25% instead of the sealer composition of Example 1. The results are shown in Table 1.

Comparative Example 3 In place of the modified PVA of Example 1, PVA-105
(Kuraray Co., Ltd., PVA, degree of polymerization 550, degree of saponification 9)
(8.5 mol%) was used in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 4 The same procedure as in Example 1 was carried out except that an existing solvent-type urethane sealer (Asbestos Sealer # 20, manufactured by Toa Paint Co., Ltd.) was used instead of the sealer composition of Example 1. Was. The results are shown in Table 1.

Comparative Example 5 Calcium silicate plate (absolute dry specific gravity 0.85, water content 7%)
Was evaluated for its performance without applying the sealer composition. The results are shown in Table 1.

Example 2 12 g of PVA having a mercapto group at the terminal (PVA-2; degree of polymerization: 400, degree of saponification: 98.5 mol%) was dissolved by heating in 290 g of ion-exchanged water. It was charged in a pressure-resistant autoclave provided. PH with diluted sulfuric acid
= 4.0, 165 g of styrene and then 135 g of butadiene were charged from a pressure gauge, and the temperature was raised to 70 ° C.
10 g of a 2% aqueous solution of potassium persulfate was injected to initiate polymerization. The internal pressure decreased from 4.8 kg / cm ² with the progress of polymerization, and reached 0.4 kg / cm ² after 15 hours, and the polymerization rate was determined to be 99.3%. The obtained emulsion was adjusted to pH = 6.0 with aqueous ammonia, and the solid concentration was 49.0.
% Aqueous emulsion (II) having a viscosity of 2600 cp. A sealer composition was obtained and tested in the same manner as in Example 1, except that the aqueous emulsion (I) in Example 1 was replaced with the aqueous emulsion (II). The results are shown in Table 1.

Comparative Example 6 PVA having a mercapto group at the terminal of Example 1 (PVA
-1), a nonionic surfactant (Nonipol 2)
00, manufactured by Sanyo Chemical Co., Ltd.)
Solid concentration: 50.8%, viscosity: 75 c as in Example 1.
An aqueous emulsion (III) having a p and a pH of 6.8 was obtained. The aqueous emulsion (I) of Example 1 was replaced with the aqueous emulsion (II)
A sealer composition was obtained and tested in the same manner as in Example 1 except that I) was replaced. The results are shown in Table 1.

Example 3 A water-dispersible isocyanate compound (Coronate C-3) was added to 100 parts of the composition of Example 1 as a water-proofing agent.
053; manufactured by Nippon Polyurethane Co., Ltd.) and tested in the same manner as in Example 1. The results are shown in Table 1.

[0054]

[Table 1]

[0055]

[Table 2]

As shown in Table 1, the composition of the present invention has no coating defects, and is excellent in water stopping performance, surface layer reinforcing effect, and adhesion to the top coating (application directly and after weathering).

Examples 4 to 6 and Comparative Examples 7 and 8 Modified PVA and aqueous emulsion (I) in Example 1
A sealer composition was obtained in the same manner as in Example 1 except that the compounding ratio of the sealer composition was changed as shown in Table 2, and the same performance evaluation as in Example 1 was performed. The results are shown in Table 2.

[0058]

[Table 3]

[0059]

[Table 4]

[0060]

As described above, the composition of the present invention is used for various uses, and is particularly suitable as a sealer for a porous inorganic plate. The composition of the present invention is water-based and hardly causes coating defects, and has a surface reinforcing effect comparable to that of a solvent-based sealer, water-stopping performance, moisture resistance and hot water resistance even when applied once, and a sealer. It is extremely useful as an industrial material in which excellent adhesion to a finishing material can be obtained even after being left for a long time after the treatment.
Further, the composition of the present invention can be used as an inorganic binder, a coating agent for an inorganic plate, and an antifogging agent in addition to the use as a sealer of the porous inorganic plate.

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C09D 5/34

Claims (3)

(57) [Claims] 1. A modified polyvinyl alcohol (A) containing 0.01 to 5 mol% of a silyl group in a molecule and an acrylic ester monomer unit, a methacrylic ester monomer unit, and styrene Is a homopolymer or copolymer containing one or more monomer units selected from monomer units and diene monomer units, and the dispersant is a polyvinyl alcohol-based polymer having a mercapto group at a terminal. A composition comprising a certain aqueous emulsion (B), wherein the solids content ratio (A) / (B) is 5/95 to 50/50 on a weight basis. 2. The composition according to claim 1, which comprises a water-proofing agent (C) as the component (A). 3. A sealer composition for a porous inorganic plate, comprising the composition according to claim 1.