JPH06248228A - Resin composition for coating - Google Patents

Abstract

PURPOSE:To obtain a coating resin composition useful for concrete, mortar, etc., having a modified polyvinyl acetal resin containing a specific amount of silicon containing functional groups in a molecule as an essential component and excellent in waterproofness, alkali resistance, etc. CONSTITUTION:The composition consists of a modified polyvinyl acetal resin containing 0.01-10mole% silicon containing functional group in a molecule as an essential component and preferably a condensation catalyst (e.g. dibuthyl tin acetate, etc.) and, if needed, a filler, a pigment, etc. The resin is obtained by acetalizing a modified polyvinyl alcohol (preferably 70-100mole% degree of saponification) having silicon containing functional groups obtained by modification, etc., after subjecting polyvinyl alcohol or modified polyvinyl acetate to react with a chemical (e.g. trimethylchlorosilane, etc.) containing an organic solvent (e.g. benzene, etc.).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition for paints, and more specifically, it contains a modified polyvinyl acetal resin having a reactive silicon-containing functional group in its molecule as an essential component, and has water resistance, alkali resistance and weather resistance. Excellent in sex,
For example, the present invention relates to a resin composition for a solvent type coating material which is preferably used as an inorganic material such as concrete, mortar and slate.

[0002]

2. Description of the Related Art Conventionally, from the viewpoints of waterproofing, protecting inorganic materials such as concrete, mortar, and slate, and ensuring the appearance, various materials are used to coat these materials. And as the paint, for example,
Organic solvent type paints such as urethane resin type, epoxy resin type, acrylic resin type, or water-based emulsion type paints are used. Among these paints, vinyl ester-
A coating material containing a (meth) acrylic acid ester copolymer as a vehicle is preferred because it is inexpensive, has excellent adhesiveness to an inorganic material, and has good waterproofness.

However, a coating material using such a copolymer is insufficient in long-term weather resistance, and is not sufficient in terms of water resistance and alkali resistance. When exposed to wind and rain or heat, the coating often cracks, pierces, elutes, loses its luster, and spoils its appearance. Therefore, for example, when it is applied to an exterior member such as slate roof tile, it is customary to recoat it in a few years, and also in the case of other members, vinyl ester- (meth) acrylic acid is used. In many cases, another type of paint was further coated on the ester copolymer paint for use.

[0004]

Under these circumstances, the present invention is excellent in water resistance, alkali resistance, weather resistance and the like, and is suitably used for inorganic materials such as concrete, mortar and slate. The purpose of the invention is to provide a resin composition for paint.

[0005]

Means for Solving the Problems In order to develop a resin composition for coating materials having the above-mentioned preferable properties, the present inventor has extensively studied chemical modification of polyvinyl alcohol, which is a raw material of polyvinyl acetal resin. As a result, a polyvinyl acetal resin was produced using the obtained modified polyvinyl alcohol, and when evaluated, a modified polyvinyl acetal resin having a silicon-containing functional group derived from a polyvinyl alcohol having a silicon-containing functional group in the molecule was coated. It was found that the film has excellent weather resistance, alkali resistance, water resistance, and the like, as well as excellent adhesion to inorganic materials. The present invention has been completed based on such findings. That is, the present invention, in the molecule,
The present invention provides a resin composition for coatings, which contains a modified polyvinyl acetal resin containing 0.01 to 10 mol% of a silicon-containing functional group as an essential component.

In the composition of the present invention, the modified polyvinyl acetal resin having a silicon-containing functional group in the molecule, which is used as an essential component, uses a modified polyvinyl alcohol having a silicon-containing functional group in the molecule as a raw material. The modified polyvinyl alcohol having a silicon-containing functional group in the molecule is not particularly limited as long as it has a silicon-containing functional group in the molecule. There are various methods for producing such a modified vinyl alcohol. For example, (1) polyvinyl alcohol or modified polyvinyl acetate having a carboxyl group or a hydroxyl group is post-modified with a suitable agent to give a silicon-containing functional group. Preferable examples include a method of introducing a group and a method of (2) saponifying a copolymer of a vinyl ester and an olefinically unsaturated monomer having a silicon-containing functional group.

In the method (1) of post-modifying polyvinyl alcohol or modified polyvinyl acetate with a suitable agent, an organic solvent which is usually inert to the agent, such as benzene, toluene, xylene, hexane, The drug is dissolved in heptane, diethyl ether, acetone, etc., and powdered polyvinyl alcohol or the above-mentioned modified polyvinyl acetate is suspended in this solution under stirring, and the drug is maintained at room temperature to a boiling point of the drug. A modified polyvinyl alcohol having a silicon-containing functional group can be obtained by reacting a vinyl acetate unit with polyvinyl alcohol or the above-mentioned modified polyvinyl acetate, or by saponifying a vinyl acetate unit with an alkali catalyst or the like.

Examples of the agent used for the post-modification include trimethylchlorosilane; dimethyldichlorosilane;
Methyltrichlorosilane; Vinyltrichlorosilane; Diphenyldichlorosilane; Organohalogenosilane such as triethylfluorosilane, trimethylacetoxysilane; Organosilicone ester such as dimethyldiacetoxysilane, trimethylmethoxysilane; Organoalkoxysilane such as dimethyldimethoxysilane, trimethylsilanol And organosilanols such as diethylsilanediol, aminoalkylsilanes such as N-aminoethylaminopropyltrimethoxysilane, and organosilicone isocyanates such as trimethylsilicone isocyanate. The introduction rate of the silicon-containing functional group, that is, the modification rate is the amount of the drug used,
It can be optionally adjusted depending on the reaction time and the like. The degree of polymerization and saponification of the obtained modified polyvinyl alcohol having a silicon-containing functional group can be arbitrarily adjusted by the degree of polymerization and saponification of the polyvinyl alcohol used, or the degree of polymerization and saponification reaction of the modified polyvinyl acetate. You can

On the other hand, in the method (2) of saponifying a copolymer of a vinyl ester and an olefinically unsaturated monomer having a silicon-containing functional group, the vinyl ester is saponified in a suitable solvent such as alcohol. An olefinically unsaturated monomer having a silicon-containing functional group is copolymerized with a radical initiator, and then an alkali or acid catalyst is added to this solution to saponify the resulting copolymer. A modified polyvinyl alcohol having a silicon-containing functional group can be obtained.

Examples of the vinyl ester used in the above method include vinyl acetate, vinyl propionate,
Examples thereof include fatty acid vinyl such as vinyl formate and vinyl versatate, and aromatic vinyl ester such as vinyl benzoate. These may be used alone or in combination of two or more, and among these, vinyl acetate is most preferable from the viewpoint of economy. Further, as the olefinically unsaturated monomer having a silicon-containing functional group used in the above method, vinylsilane represented by the general formula (I), (meth) represented by the general formula (II) or (III) Acrylamide-alkylsilane and the like can be mentioned as preferable ones.

[0011]

[Chemical 1]

(Wherein R ¹ is a hydrogen atom, a halogen atom,
A lower alkyl group, an aryl group or a lower alkyl group having an aryl group, R ² is a halogen atom, an alkoxyl group,
An acyloxyl group (wherein the alkoxyl group or the acyloxyl group may have a substituent containing an oxygen atom or a nitrogen atom), a hydroxyl group or an alkyl group, R ³ is a hydrogen atom or a methyl group, and R ⁴ is a lower group. Alkyl group, R ⁵ is an alkylene group or a divalent organic residue in which chain carbon atoms are mutually bonded by an oxygen atom or a nitrogen atom, and n is 0.
Is an integer of 10 and m is 0, 1 or 2. )

In the above general formulas (I), (II), and (III), R ² is a halogen atom, an alkoxyl group, an acyloxyl group, a hydroxyl group or an alkyl group, and the reactivity of the silicon-containing functional group is obtained. From the viewpoint of viscosity stability of the copolymer solution, an alkoxyl group and an acyloxyl group are preferable, and an alkoxyl group is particularly preferable. When R ² is a halogen atom, since the reactivity of the silicon-containing functional group is too strong, the coating solution tends to thicken or gel during storage, so it is necessary to pay sufficient attention to the water content in the solution. is there. Further, m is 0, 1 or 2, but the smaller m is, the greater the reactivity of the silicon-containing functional group becomes, and the effect of the silicon-containing functional group introduced into the copolymer can be efficiently brought out. Becomes Conversely, the larger m is, the better the storage stability of the coating solution tends to be. Therefore, it is preferable to appropriately select the value of m depending on the introduction amount of the silicon-containing functional group in the copolymer, the type of the R ² group, and the like.

Specific examples of the olefinically unsaturated monomer having a silicon-containing functional group represented by the above general formula (I) include vinyltrimethoxysilane, vinyltrichlorosilane, vinyltriethoxysilane and vinyltriacetoxysilane. , Vinyltris (2-methoxyethoxy) silane, vinyltriisopropoxysilane, vinyltriphenoxysilane, vinylmethyldichlorosilane, vinylmethyldimethoxysilane, vinyldimethylethoxysilane, vinyldimethyldichlorosilane and other vinyl group-containing silane compounds, 3- Methacryloxy group-containing silane compounds such as methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldichlorosilane, 3-methacryloxypropylmethyldimethoxysilane, 3-
Examples thereof include acryloxy group-containing silane compounds such as acryloxypropyltrimethoxysilane, and allyl group-containing silane compounds such as allyltriethoxysilane, 3-allylthiopropyltrimethoxysisilane, and allylmethyldichlorosilane.

Specific examples of the olefinically unsaturated monomer having a silicon-containing functional group represented by the above general formulas (II) and (III) include 3- (meth) acrylamido-propyltrimethoxysilane, 3- (meth) acrylamide-propyltriethoxysilane, 3- (meth) acrylamide-propyltri (β-methoxyethoxy) silane, 3- (meth) acrylamide-propyltri (N-
Methylaminoethoxy) silane, 2- (meth) acrylamide-ethyltrimethoxysilane, 1- (meth) acrylamide-methyltrimethoxysilane, 2- (meth)
Acrylamido-2-methyltrimethoxysilane, 2-
(Meth) acrylamido-isopropyltrimethoxysilane and other (meth) acrylamide-linear or branched alkyltrialkoxysilanes, N- [2- (meth) acrylamido-ethyl] -aminopropyltrimethoxysilane, [3- (meta) (Meth) acrylamide-nitrogen-containing or oxygen-containing alkyltrialkoxysilane such as acrylamido-propyl] -oxypropyltrimethoxysilane, 3- (meth) acrylamide-propyltriacetoxysilane, 2- (meth) acrylamide-ethyltriacetoxysilane , 4- (meth) acrylamide-butyltriacetoxysilane, 3- (meth) acrylamide-propyltripropionyloxysilane, 2- (meth)
Acrylamide-2-methylpropyltriacetoxysilane, N- [2- (meth) acrylamido-ethyl]-
Acrylamide-alkyltriacyloxysilane such as 2-aminopropyltriacetoxysilane, 3- (meth) acrylamido-propylisobutyldimethoxysilane, 2- (meth) acrylamido-ethyldimethylmethoxysilane, 3- (meth) acrylamido-propyloctyldisilane. Acetoxysilane, 1- (meth) acrylamide-methylphenyldiacetoxysilane, 3- (meth) acrylamide-propylbenzyldiethoxysilane, 2- (meth) acrylamide-2-methylpropylmonochlorodimethoxysilane, 2- (meth) acrylamide (Meth) acrylamido-alkyldi or monoalkoxy or di or monoacyloxysilane such as 2-methylpropylhydrodimethoxysilane, 3- [N
[N-alkyl- (meth) acrylamide] -alkyltrialkoxy or triacyloxy such as -methyl- (meth) acrylamide] -propyltrimethoxysilane, 2- [N-ethyl- (meth) acrylamide] -ethyltriacetoxysilane Examples thereof include silane and N, N-di-trialkylsilyl (meth) acrylamide such as N, N-di-trimethylsilyl (meth) acrylamide.

In the method, in copolymerizing the vinyl ester and the olefinically unsaturated monomer having a silicon-containing functional group, other than the above-mentioned two components, other copolymerizable monomers can be used. Unsaturated monomers such as styrene, alkyl vinyl ether, vinyl versatate, (meth) acrylamide, ethylene, propylene,
Olefins such as α-hexene and α-octene, unsaturated acids such as (meth) acrylic acid, crotonic acid, (anhydrous) maleic acid, fumaric acid and itaconic acid, and their alkyl esters and alkali salts, 2-acrylamido-2- Sulfonic acid-containing monomers such as methylpropanesulfonic acid and alkali salts thereof, trimethyl-3- (1-acrylamido-1,1-dimethylethyl) ammonium chloride, trimethyl-3- (1-acrylamidopropyl) ammonium chloride, 1 It is also possible to allow a small proportion of cationic monomers such as -vinyl-2-methylimidazole and its quaternary compounds to be present.

In the present invention, the degree of saponification and the degree of polymerization in the modified polyvinyl alcohol having a silicon-containing functional group used as a raw material for the modified polyvinyl acetal resin having a silicon-containing functional group are not particularly limited and may be appropriately selected depending on the purpose. To be selected. The silicon-containing functional group is effective even with a relatively small content, but in the present invention, it is preferably selected in the range of 0.01 to 10 mol%.
If the content is less than 0.01 mol%, the effect of the present invention may not be sufficiently exhibited, and if it exceeds 10 mol%, the viscosity stability of the coating solution may be reduced, or the coating film may become hard and brittle. It may lead to an unfavorable situation. Also,
The degree of saponification is usually preferably in the range of 70 to 100 mol%.

Further, the degree of polymerization is usually 100 to 5000.
However, the range is preferably 300 to 4000, more preferably 500 to 3000. If the degree of polymerization is less than 100, the strength of the coating film is insufficient, and cracking, blistering, and peeling are likely to occur. If it exceeds 5000, the amount of silicon-containing functional groups introduced is relatively small, but
Since the viscosity of the coating solution increases, it may not be possible to increase the concentration of the modified polyvinyl acetal resin in the coating solution, which may cause an unfavorable situation. The modified polyvinyl alcohol having a silicon-containing functional group thus obtained is then acetalized to obtain a polyvinyl acetal resin. Among these polyvinyl acetal resins, polyvinyl butyral resin is suitable for the purpose of the present invention. The acetalization is carried out in the same manner as the conventional method for producing a polyvinyl acetal resin.

In the above, a method of producing a modified polyvinyl alcohol having a silicon-containing functional group and then acetalizing the modified polyvinyl alcohol has been mainly described. In the saponification step during the production of the modified polyvinyl alcohol having a silicon-containing functional group, The modified polyvinyl acetal resin of the present invention can be obtained by simultaneously performing the saponification reaction and the acetalization. This acetalization is usually selected in the range of 50 to 80 mol%. The modified polyvinyl acetal resin having a silicon-containing functional group in the molecule used in the present invention, particularly those obtained by saponifying and acetalizing a copolymer of vinyl acetate and vinyltriacyloxysilane or vinyltrialkoxysilane, And those obtained by saponifying and acetalizing a copolymer of vinyl acetate and (meth) acrylamide-alkylalkoxysilane.

After coating, the coating material containing the polyvinyl acetal resin of the present invention as the main component is gradually hydrolyzed at room temperature due to moisture in the air or the base material to produce a silanol group, whereby the Si-R ² group is produced. This silanol group is dehydrated and condensed to crosslink and cure, or the silanol group reacts with an inorganic material to increase the adhesiveness with the substrate, but simply by coating the polyvinyl acetal resin of the present invention, curing Since it takes a long time to react with the substrate, it is preferable to shorten the reaction time by using a condensation catalyst of Si-R ² group together.
As the condensation catalyst used at this time, known tin compounds such as dibutyltin diacetate and dibutyltin dilaurate, titanium compounds such as alkyl titanates, acid catalysts such as p-toluenesulfonic acid, alkylamines, sodium hydroxide. Basic catalysts such as can be suitably used. These condensation catalysts may be a two-pack type that is used as a mixture with the paint at the time of coating, or a small amount is mixed in advance with the paint.
It is also possible to use a one-pack type. However, in the case of a one-pack type, the type and amount of the catalyst are limited from the viewpoint of storage stability, and it is necessary to control the water content in the paint to a minimum.

The polyvinyl acetal resin of the present invention may be applied alone or may be blended with a known filler such as clay, kaolin or calcium carbonate. Further, various pigments such as carbon black, aluminum powder, red iron oxide, chrome green, titanium white, and yellow lead can be added. Further, known additives such as a plasticizer and a pigment dispersant may be blended, if necessary. When applying the resin composition for paints containing the polyvinyl acetal resin of the present invention as a main component, known application methods such as iron coating, spraying and brush coating can be used. The coating resin composition containing the polyvinyl acetal resin as the main component of the present invention alone can achieve sufficient adhesion to substrates, water resistance, alkali resistance, and weather resistance, but other coating materials may be used as necessary. It does not matter if you apply a base coat or a top coat.

[0022]

The present invention will be described in more detail by way of examples, which should not be construed as limiting the invention thereto. Example 1 By saponifying a copolymer composed of 0.4 mol% of vinyltriacetoxysilane units and 99.6 mol% of vinyl acetate units, silicon-containing functional groups were converted into vinylsilane units.
It contains 0.4 mol% and the degree of saponification of vinyl acetate units is 99.4.
A modified polyvinyl alcohol having a silicon-containing functional group with a mol% and a degree of polymerization of 1700 was obtained. Next, 10 parts by weight of this modified polyvinyl alcohol was put in 90 parts by weight of water, dissolved by heating under stirring, and then cooled to 40 ° C. While stirring at 40 ° C., add 6.5 parts by weight of 35% by weight concentrated hydrochloric acid,
Further addition of 5.2 parts by weight of butyraldehyde produced a white precipitate of modified polyvinyl butyral. After further aging at 40 ° C. for 4 hours, the reaction was terminated, the resin was neutralized and washed with water to obtain a butyralization degree of 63 mol% and a silicon-containing functional group as a vinylsilane unit containing 0.4 mol%. A polyvinyl butyral resin was obtained. This modified polyvinyl butyral resin is abbreviated as [A].

50 parts by weight of this modified polyvinyl butyral resin was placed in a mixed solution of 35 parts by weight of toluene and 15 parts by weight of ethyl acetate, dissolved by heating with stirring, and then cooled to room temperature. At this time, the viscosity was 15,000 cps at 20 ° C. Using this modified polyvinyl butyral resin toluene solution, a coating solution was prepared at the compounding ratio shown in the compounding example 1 of Table 2. 100 thus obtained coating solution
Parts by weight were diluted to a spray viscosity with a mixed solvent of ethyl acetate and toluene in a weight ratio of 1: 1 and 0.06 parts by weight of dibutyltin diacetate was added to make the coating film thickness after drying 4
The slate plate was spray-coated so that the thickness became 0 μm.

Examples 2 to 6 The same as Example 1 except that the modified polyvinyl alcohol having a silicon-containing functional group shown in Table 1 was used in place of the modified polyvinyl alcohol having a silicon-containing functional group of Example 1. In this way, a modified polyvinyl butyral resin solution was obtained, and a coating solution was prepared at the compounding ratio shown in Table 2. A slate plate was spray-coated with these coating solutions in the same manner as in Example 1. Table 3 shows the results of testing the coating films of Examples 1 to 6.

Comparative Example 1 Instead of the modified polyvinyl alcohol having a silicon-containing functional group of Example 1, the saponification degree was 99.1 mol% and the degree of polymerization was 17
A polyvinyl butyral resin was obtained in the same manner as in Example 1 except that polyvinyl alcohol No. 00 was used, and a coating solution was prepared in the mixing ratio shown in Table 2 and spray coated on a slate plate in the same manner as in Example 1. . The test results are shown in Table 3.

Comparative Examples 2 and 3 A slate plate was prepared in the same manner as in Example 1 except that two commercially available vinyl acetate-methyl methacrylate-based silver black paints were used and dibutyltin diacetate was not used. Spray painted on. The test results of the coating film are shown in Table 3.

[0027]

[Table 1]

[0028]

[Table 2]

[0029]

[Table 3]

Note) Water resistance: 30 days after immersion in water Alkali resistance: 10 days immersion in saturated aqueous solution of calcium hydroxide Weather resistance: 24 months Outdoor exposure Evaluation code: ◎: No abnormalities ○: Almost no abnormalities △: Partially abnormalities Yes ×; Abnormal on the whole surface

Examples 7 to 10 and Comparative Examples 4 to 7 Using polyvinyl butyral resins [A] and [G],
A coating solution was prepared in the mixing ratio shown in Table 4, and coated on a slate plate in the same manner as in Example 1. The test results of the coating film are shown in Table 5.

[0032]

[Table 4]

[0033]

[Table 5]

Note) The test method and evaluation method are the same as in Table 3.
From Tables 3 and 5, it is clear that the resin composition for coating material using the modified polyvinyl butyral resin having a silicon-containing functional group of the present invention is excellent in water resistance, alkali resistance and weather resistance.

[0035]

As is apparent from the above description, the coating composition using the resin composition for coating composition of the present invention has excellent weather resistance, water resistance and
It is extremely excellent in alkali resistance, and can remarkably improve the performance of vinyl ester (meth) acrylic acid ester copolymer-based paints that required re-coating in the past 2-3 years, or required top-coating of other types of paints. . The reason why such remarkable performance is obtained is not necessarily clear, but is estimated as follows. That is, the silicon-containing functional group introduced in the present invention is hydrolyzable, and after being applied to the substrate, it is hydrolyzed to form silanol by the action of moisture in the air or the substrate, or a condensation catalyst. As a result, the silanol groups are dehydrated and condensed to crosslink and cure the coating film, or the silanol groups react with the inorganic material to increase the adhesion to the base material, thereby improving the weather resistance,
It is presumed that the water resistance and alkali resistance will be remarkably improved.

Claims (1)

[Claims] 1. A silicon-containing functional group 0.01 to 10 in the molecule.
A resin composition for coatings, which contains a modified polyvinyl acetal resin containing mol% as an essential component.