JPH10212437A - Resin composition for coating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition comprising a coating film-forming resin, a tetrafunctional hydroyzable silane compound and a silane coupling agent, capable of preventing the generation of stains due to rain water-flowing routes on a coated product, capable of exhibiting excellent recoatability, and useful for coating outdoor articles. SOLUTION: This resin composition for coatings comprises (A) a coating film-forming resin such as a fluororesin containing functional groups (e.g. OH, carboxyl, epoxy, amino or hydrolyzable silyl groups), (B) a tetrafunctional hydrolyzable silane compound such as a tatra(1-2C)alkoxysilane or its polymer, and (C) a silane coupling agent (e.g. an amino group-having silane oligomer). The components A, B and C are contained in amounts of e.g. 100 pts.wt., (1-50) pts.wt., and (0.1-50) pts.wt., respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a resin composition for a paint.

[0002]

2. Description of the Related Art Conventionally, metals, inorganics, plastics,
Products such as wood, paper, leather, textile, etc., protect their surface,
2. Description of the Related Art Surface coating such as painting is performed for the purpose of imparting designability and functionality, and paints have been variously developed.

[0003] Recently, fluorine resin paints have been widely used as paints having excellent weather resistance. This fluororesin paint exhibits remarkable weather resistance as compared with various synthetic resin paints which have been widely used before. However, the antifouling property against dirt on the surface is almost the same as that of other synthetic resin paints.
The improvement is desired.

[0004]

Heretofore, there has been proposed a coating composition to which a polymer having a polyfluorinated carbon chain and a hydrophilic group is added in order to solve the stain on the surface of a coated article (for example, Japanese Patent Application Laid-Open No. H11-163, 1988). See Heikai 1-198653). However, although the proposed coating composition is effective in preventing the formation of stains on the spots caused by rainwater, it is possible to prevent streaks from being generated in areas where rainwater gathers and flows such as under outdoor articles such as window frames of buildings. It is not sufficient to prevent the state of dirt (hereinafter referred to as rain streak dirt).

Further, there has been proposed a coating composition containing a condensate of an organosilicate (WO94 / 06).
870). However, although the composition of this proposal has an effect of reducing rain streak when observed over a long period of time, it has a problem that rain streak easily occurs in the early stage of outdoor exposure.
In addition, when the same type of paint is repainted (recoated) on the coating film of this composition, adhesion between the layers is low, and peeling may occur.

[0006]

The present invention solves the above-mentioned problems, and comprises a film-forming resin (a), a tetrafunctional hydrolyzable silane compound or a polymer thereof (b), and a silane coupling agent (b). It is a resin composition for coatings containing c).

[0007] The composition of the present invention is applied to outdoor articles at locations where rain streak is likely to occur, or the articles coated with the composition of the present invention are used at locations where rain streak is likely to occur. In addition, the generation of rain streak can be prevented for a long period of time, and the adhesion between layers is excellent even when recoated.

The film-forming resin (a) (hereinafter simply referred to as the resin (a)) can be used in a wide range without any particular limitation, and a resin called a coating resin is usually used. Specifically, resins such as a fluorine resin, an acrylic resin, a polyester resin, an alkyd resin, and a silicone resin, and a polyester-modified acrylic resin are also included. These resins may be used alone as a film-forming resin, or may be used as a film-forming resin in combination with a curing agent.

Above all, fluororesins have excellent weather resistance,
This is preferable because the effect of preventing rain streaking is effectively exhibited for a long period of time. Further, as the fluororesin, a combination of a functional group-containing fluororesin and a curing agent and / or a curing catalyst reactive with the functional group is preferable in that it can be applied at normal temperature. As such a functional group-containing fluororesin, a hydroxyl group-containing fluororesin is well known. Other functional groups include a carboxyl group, an epoxy group, an amino group, and a hydrolyzable silyl group.

As the functional group-containing fluororesin, a fluoroolefin and a copolymer obtained by copolymerizing a monomer copolymerizable with the fluoroolefin have properties such as solubility in a solvent, weather resistance of a coating film, and coating workability. Is preferred.

Examples of the fluoroolefin include those having 2 to 3 carbon atoms such as tetrafluoroethylene, chlorotrifluoroethylene, trifluoroethylene, vinylidene fluoride, hexafluoropropylene and pentafluoropropylene.

The monomers copolymerizable with the fluoroolefin include vinyl ether, vinyl ester, allyl ether, allyl ester, isopropenyl ether, isopropenyl ester, methallyl ether, methallyl ester, α-olefin, acrylate,
At least one monomer selected from methacrylic acid esters and the like is included.

Here, as the vinyl ether, ethyl vinyl ether, butyl vinyl ether, cyclohexyl vinyl ether, fluoroalkyl vinyl ether,
Examples include alkyl vinyl ethers such as perfluoro (alkyl vinyl ether).

The vinyl ester is a fatty acid vinyl ester having a branched alkyl group, Veovar-10.
(Trade name, manufactured by Shell Chemical Co., Ltd.), and fatty acid vinyl esters such as vinyl butyrate, vinyl acetate, vinyl pivalate, and vinyl versatate.

Examples of the allyl ether include alkyl allyl ethers such as ethyl allyl ether and cyclohexyl allyl ether. Examples of the allyl ester include fatty acid allyl esters such as allyl propionate and allyl acetate. Examples of the isopropenyl ether include an alkyl isopropenyl ether such as methyl isopropenyl ether. Examples of the α-olefin include ethylene, propylene, and isobutylene.

If the copolymerization ratio of the fluoroolefin is too small, sufficiently excellent weather resistance as a weather-resistant paint cannot be exhibited. On the other hand, if the copolymerization ratio of the fluoroolefin is too large, it is not preferable because the solubility in a solvent and the like decrease. Therefore, as the resin, the proportion of the fluoroolefin is 30 to 70 mol%, particularly 40 to 6 mol%.
The copolymer is preferably copolymerized at a ratio of 0 mol%.

The resin is preferably copolymerized with the above compound in addition to the fluoroolefin, from the viewpoint of solubility in a solvent and the like. Particularly, vinyl ether, vinyl ester, allyl ether, and allyl ester are preferable because of their excellent copolymerizability with fluoroolefin. Further, alkyl vinyl ethers having a linear, branched or alicyclic alkyl group having 1 to 10 carbon atoms, fatty acid vinyl esters, alkyl allyl ethers, and fatty acid allyl esters are preferred.

The copolymer has a functional group capable of undergoing a cross-linking reaction with a curing agent, in addition to the above-mentioned copolymer components, so that a tougher coating film can be obtained. Examples of the functional group include an active hydrogen-containing group capable of reacting with an isocyanate-based curing agent and an aminoplast-based curing agent, such as a hydroxyl group, an amino group, an amide group, and a carboxyl group. In addition, functional groups such as an epoxy group, a halogen, a double bond, and a hydrolyzable silyl group are also exemplified.

As a method for introducing such a functional group, a monomer having a functional group, for example, hydroxybutyl vinyl ether, hydroxybutyl allyl ether, ethylene glycol monoallyl ether, cyclohexanediol monovinyl ether, acrylic acid, methacrylic acid, Crotonic acid, undecenoic acid, glycidyl vinyl ether,
There is a method of copolymerizing glycidyl allyl ether, trimethoxyvinylsilane, or the like.

A method of introducing a functional group by modifying a copolymer, for example, a method of reacting a hydroxyl group or an epoxy group with a polybasic acid anhydride such as succinic anhydride to introduce a carboxyl group, The functional group can also be introduced by a method such as a method of reacting isocyanate alkyl methacrylate or the like to introduce a double bond.

The copolymer unit having a functional group is preferably 5 to 20 mol% in the copolymer.

As such a functional group-containing fluororesin,
For example, commercially available as Lumiflon (Asahi Glass), Sefral Coat (Central Glass), Zaffron (Toagosei), Zeffle (Daikin Industries), Fluonate (Dainippon Ink Industries), Floren (Nippon Synthetic Rubber), Kynar (Atochem), etc. Can be used.

The curing agent is not particularly limited as long as it can crosslink the functional group-containing fluororesin. Examples of those which undergo a crosslinking reaction with an active hydrogen-containing resin at ordinary temperature include polyvalent isocyanate compounds. Examples of the curing agent used for baking coating as a one-component paint include an aminoplast-based curing agent, a blocked isocyanate-based curing agent, and a polybasic acid-based curing agent.

As the aminoplast-based curing agent, methylolmelamines, methylolguanamines, methylolureas and the like can be used. Examples of the methylol melamines include methylol melamine etherified with a lower alcohol such as butylated methylol melamine and methylated methylol melamine, and epoxy-modified methylol melamine. Examples of the methylol ureas include alkylated methylol ureas such as methylated methylol urea and ethylated methylol urea. When an aminoplast-based curing agent is used, a crosslinking reaction can be promoted by adding an acidic catalyst.

As the blocked isocyanate-based curing agent, there is a blocked product of a polyvalent isocyanate compound.
The polyvalent isocyanate compound is a compound having two or more isocyanate groups, and may be a compound having two or more isocyanate groups, which is a modified or multimeric form thereof. Polyvalent isocyanate compounds, specifically, aliphatic polyvalent isocyanate compounds such as ethylene diisocyanate, propylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, hexamethylene triisocyanate, lysine diisocyanate, isophorone diisocyanate, dicyclohexyl methane diisocyanate, diisocyanate methyl cyclohexane, etc. And non-yellowing aromatic isocyanate compounds such as m-xylene diisocyanate and p-xylene diisocyanate.

Examples of modified polymers and multimers of polyvalent isocyanate compounds include those referred to as urethane-modified, urea-modified, isocyanurate-modified, buret-modified, allophanate-modified and carbodiimide-modified products. is there. In particular, a modified isocyanurate which is a trimer, a modified urethane which is a reaction product with a polyhydric alcohol such as trimethylolpropane, and the like are preferable.

Preferred polyvalent isocyanate compounds include non-yellowing isocyanates such as hexamethylene diisocyanate and isophorone diisocyanate, and multimers thereof.

When a polyvalent isocyanate compound or a blocked isocyanate compound is used, the crosslinking reaction can be promoted by adding a known catalyst such as dibutyltin dilaurate.

As the polybasic acid, long chain aliphatic dicarboxylic acids, aromatic polycarboxylic acids and the like are useful, and their acid anhydrides are also useful.

A tetrafunctional hydrolyzable silane compound is a compound in which four hydrolyzable groups are directly bonded to one silicon atom. The multimer is obtained by multiplying this compound by condensation.

Examples of the hydrolyzable group include an alkoxy group, an alkoxyalkoxy group, an acyloxy group, an aryloxy group, an aminoxy group, an amide group, a ketoxime group, an isocyanate group, and a halogen atom. Preferably, it is a group obtained by removing a hydrogen atom from a hydroxyl group of a monohydric alcohol such as an alkoxy group and an alkoxyalkoxy group. Particularly, an alkoxy group is preferable, and the number of carbon atoms is preferably 4 or less, particularly preferably 1 or 2.

The polymer has a degree of multimerization that does not produce a gel-like product in the resin composition for coating. Here, the degree of multimerization means the number of condensed molecules of the tetrafunctional hydrolyzable silane compound. Multimers include those having a linear, branched, cyclic, or network structure, and usually those having a linear structure or those having a linear structure have a branched, cyclic, or network structure. Is considered to be a mixture containing As the multimer used in the present invention, those having these structures may be used alone or as a mixture of those having these structures.

Preferred multimers include multimers of tetraalkoxysilane. If this is shown as having a linear structure, the general formula RO (Si (OR) ₂ O)
_nR .

In the general formula, n represents the degree of multimerization of the multimer. Multimers that are commonly available are mixtures of multimers with different n. In the general formula, R represents a methyl group, an ethyl group,
A lower alkyl group such as a propyl group and a butyl group is exemplified. From the viewpoints of hydrolysis and condensation of the alkoxy group, R
Is preferably a polymer of tetramethoxysilane in which R is a methyl group or a polymer of tetraethoxysilane in which R is an ethyl group. A methyl group is particularly preferred from the viewpoint of exhibiting an effect with a small amount and having an effect of preventing the occurrence of rain streak stain without lowering other coating film properties. A plurality of Rs may be different in one molecule.

The degree of multimerization of a tetrafunctional hydrolyzable silane compound such as tetraalkoxysilane and a multimer thereof may be represented by "silica content". “Silica content” refers to the weight ratio of silica (SiO ₂ ) produced from the compound, and is obtained by measuring the amount of silica produced by completely hydrolyzing and calcining the compound. The “silica content” indicates the ratio of silica generated from one molecule of the compound to one molecule of the compound, and is expressed by the formula [silica content (% by weight) = multimerization degree × (molecular weight of SiO ₂ ) × 100.
/ (Molecular weight of the compound)].

In the present invention, the silane coupling agent refers to a silane compound having a hydrolyzable group directly bonded to a silicon atom and a non-hydrolyzable organic group. The non-hydrolysable organic group is bonded to the silicon atom at the terminal carbon atom. This organic group may be a hydrocarbon group having no functional group, but it is preferable that at least one organic group has a functional group.

Examples of the hydrolyzable group include an alkoxy group, an alkoxyalkoxy group, an acyloxy group, an aryloxy group, an aminoxy group, an amide group, a ketoxime group, an isocyanate group, and a halogen atom. Preferably, it is a group obtained by removing a hydrogen atom from a hydroxyl group of a monohydric alcohol such as an alkoxy group and an alkoxyalkoxy group. Particularly, an alkoxy group is preferable, and the number of carbon atoms is preferably 4 or less, particularly preferably 1 or 2.

In the silane coupling agent, the non-hydrolyzable organic group may be an organic group having a functional group.
When there is another organic group, it is usually an organic group having no functional group such as an alkyl group. Examples of the functional group in the organic group having a functional group include an amino group, an epoxy group, a mercapto group, and an isocyanate group. Further, such a silane coupling agent may be a silane oligomer which has been converted into an oligomer.

The silane oligomer as used herein is a compound obtained by condensing the same or different silane coupling agents described above, or a compound obtained by condensing the silane coupling agent described above with another hydrolyzable silane compound. The other hydrolyzable silane compound is a silane compound having only a hydrolyzable group, and the above-mentioned tetrafunctional hydrolyzable silane compound is preferable.

Preferred examples of the silane oligomer include:
Compounds in which silane coupling agents having functional groups are condensed, compounds in which silane coupling agents having functional groups are condensed with silane coupling agents having no functional groups, silane coupling agents having functional groups and tetrafunctional hydrolysis And a compound obtained by condensation of a reactive silane compound.

When condensing silane coupling agents having a functional group, it is preferable not to select a combination in which the functional groups of the organic groups react with each other. Examples of other hydrolyzable silane compounds include tetraalkoxysilanes. As the oligomer, those having a bimolecular condensate to about 10 molecular condensate are preferably used because they have good affinity with the film-forming resin.

The coupling agent having an amino group is particularly excellent in interlayer adhesion at the time of recoating, and the one which has become an oligomer is more effective.

The composition of the present invention can be used together with a solvent that dissolves the above three components. For example, ketones such as methyl ethyl ketone and methyl isobutyl ketone, esters such as butyl acetate and ethyl acetate, aromatic solvents such as xylene and toluene, further, aliphatic solvents, ether solvents, and petroleum solvents are exemplified. Is done. Two or more of these solvents may be used in combination. The composition of the present invention comprises the above 3
The components may be dispersed in an organic solvent or an aqueous medium.

In the composition of the present invention, the content of the resin (a), the tetrafunctional hydrolyzable silane compound or its multimer (b) is 0.1 to 100 parts by weight of the resin (a). 1
A ratio of 00 parts by weight is preferred. A particularly desirable ratio is a ratio of (b) 1 to 50 parts by weight to 100 parts by weight of the resin (a).

When the resin (a) is a hydroxyl group-containing fluororesin and is used in combination with a blocked isocyanate-based curing agent or a polyvalent isocyanate compound, the ratio is such that the isocyanate group is 0.1 to 1 mol of the hydroxyl group-containing fluororesin. It is preferable to use it so that it becomes 5 mol or more. If the amount is less than 0.5 mol, the curing of the coating composition is insufficient and the solvent resistance and the like may be undesirably reduced. The upper limit is not particularly limited, but the unreacted isocyanate group remains in the coating film, and may adversely affect weather resistance and other performances. As a preferable upper limit, the molar ratio of hydroxyl group to isocyanate group is about 2.0. It is. More preferably, it is 0.8 to 1.6.

When the tetrafunctional hydrolyzable silane compound or the multimer thereof (b) is a multimer of tetramethoxysilane or a multimer of tetraethoxysilane, the content thereof is 100 parts by weight of the resin (a). The proportion is preferably 1 to 50 parts by weight. When the content is less than 1 part by weight, the effect of preventing the generation of the desired rain streak is low, and when the content is more than 50 parts by weight, poor curing of the coating film is easily caused, which is not preferable.

It is considered that the tetrafunctional hydrolyzable silane compound or its multimer (b) undergoes hydrolysis near the surface of the coating film of the composition of the present invention formed on the surface of an outdoor article. A catalyst that promotes this hydrolysis may be used. As such a catalyst, a metal compound catalyst such as an acidic compound, a basic compound or a metal chelate, a metal ester, or a metal alkoxide is used. As the metal, aluminum, titanium,
Examples include silicon, tin, and zinc.

Specific examples include aluminum monoacetylacetonate bis (ethylacetoacetate) and aluminum tris (acetylacetonate). Examples of the acidic compound include organic acids such as p-toluenesulfonic acid, and examples of the basic compound include amines such as triethylamine. The catalyst is used in an amount of 0.001 to 20 parts by weight per 100 parts by weight of the polymer (b).
Preferably it is 0.01 to 10 parts by weight.

The silane coupling agent (c) is preferably used in an amount of 0.1 to 50 parts by weight based on 100 parts by weight of the resin (a). If the amount used is too small, the adhesion between the layers when the target is recoated is not improved, and if it is too large, adverse effects such as an excessively high curing speed and a shortened pot life are caused. Sometimes.
In particular, it is preferable to use 0.5 to 20 parts by weight based on 100 parts by weight of the resin (a).

The composition of the present invention may contain, in addition to the above components, a curing catalyst, a pigment, an ultraviolet absorber, a light stabilizer, a leveling agent, a matting agent, a surfactant, and an anti-sagging agent.

Examples of the material of an article having a portion where rain streak easily occurs include concrete, ALC (lightweight cellular concrete), GRC (glass fiber reinforced concrete), CFRC (carbon fiber reinforced concrete), stone, slate, and the like. Inorganic materials such as glass, organic materials such as resin and rubber such as acrylic resin, polycarbonate resin, vinyl chloride resin and polyethylene resin, metal materials such as aluminum, copper, brass, titanium, iron, stainless steel, zinc steel plate, steel plate, wood And FRP (glass fiber reinforced synthetic resin), CFRP (carbon fiber reinforced synthetic resin)
And organic-inorganic composite materials.

The composition of the present invention may be applied directly to a substrate composed of these materials, or may be applied after a surface treatment such as a primer or after an undercoat. For substrates with insufficient adhesion when directly coated,
It is preferable to perform coating after performing surface treatment such as sanding and undercoating.

The composition of the present invention is applied to, for example, the following outdoor articles where rain streak is likely to occur.
As a result, it is possible to prevent rain streaking from occurring for an extremely long time. As outdoor goods, for example, automobiles, trains, helicopters, ships, bicycles, snowmobiles, ropeways, lifts, fovercraft, motorcycles and other transport equipment, sashes, shutters, water storage tanks, doors, balconies, building skins Building materials such as panels, roofing materials, stairs, skylights, concrete fences, building exterior walls, guardrails, pedestrian bridges, sound barriers, signs, highway side walls, railway viaducts, bridges and other road members, tanks, pipes, towers, chimneys Such as plant facilities, greenhouses, greenhouses, silos, agricultural equipment such as agricultural sheets, telecommunications equipment such as electric poles, power transmission towers, and parabolic antennas, electric wiring boxes, lighting equipment, air conditioners, and electric appliances such as washing machines. Equipment and its covers, monuments, tombstones, paving materials, windshields, tarpaulins, architectural curing sheets, etc. And the like.

The composition of the present invention can be applied by any ordinary coating method, for example, brush coating, roller coating, spray coating, coating with a flow coater, etc., without particular limitation.

[0055]

【Example】

Example 1 (Example) Xylene solution (solid content 60% by weight, hydroxyl value 50) of a hydroxyl group-containing fluororesin (copolymer of chlorotrifluoroethylene / cyclohexylvinyl ether / ethyl vinyl ether / hydroxybutyl vinyl ether) 16
7 parts by weight of titanium oxide (CR-90 manufactured by Ishihara Sangyo) 80
Parts by weight and 85 parts by weight of butyl acetate were added and mixed uniformly.

Further, 20 parts by weight of a tetramethoxysilane polymer (silica content: 51% by weight), aluminum monoacetylacetonate bis (ethylacetoacetate) 0.1 part by weight.
5 parts by weight, polyvalent isocyanate compound (Coronate-HX manufactured by Nippon Polyurethane: NCO content: 21.3% by weight) 1
8.5 parts by weight of a silane oligomer having an amino group (toluene containing 15% by weight of an oligomer which is an average three-molecule condensate based on a silane coupling agent having an amino group)
Xylene / ethyl acetate mixed solvent solution: K manufactured by Shin-Etsu Chemical Co., Ltd.
BP-43) (10 parts by weight) was added to obtain a coating composition 1.

The composition was coated on an aluminum plate, cured at 5 ° C. and 20 ° C. for a curing period of 1 day and 7 days, and treated with a sunshine weather meter (S-WO).
M) The same paint was applied (recoated) to the test specimen after the test for 300 hours and dried at room temperature for one week, and then the interlayer adhesion (cross-cut tape peel test: JIS K5400 8.5.
2) was tested. The painted test piece was folded in half, and exposed to the outside (Kawasaki City) with the painted surface outside so that the upper part was at an angle of 30 degrees from the horizontal plane and the lower part was vertical. The occurrence of rain streak stains two months after the exposure was observed. Table 1 shows the results.

Example 2 (Example) In Example 1, a polymer of tetraethoxysilane was used instead of the polymer of tetramethoxysilane (silica content: 40% by weight).
Was changed to 50 parts by weight.

Example 3 (Example) In Example 1, a polymer of tetramethoxysilane was used instead of the polymer of tetramethoxysilane (silica content: 59% by weight).
Was changed to 5 parts by weight.

Example 4 (Example) A test was conducted in the same manner as in Example 1, except that the silane oligomer was changed to 5 parts by weight.

Example 5 (Comparative Example) A test was conducted in the same manner as in Example 1 except that no silane oligomer was used.

[0062]

[Table 1]

[0063]

The article coated with the composition for a fluorinated paint of the present invention does not generate rain streak stains. Is excellent. Also, the adhesion between layers during recoating is excellent.

Claims (6)

[Claims] 1. A resin composition for coatings comprising a film-forming resin (a), a tetrafunctional hydrolyzable silane compound or a polymer thereof (b) and a silane coupling agent (c). 2. The composition according to claim 1, wherein the tetrafunctional hydrolyzable silane compound is a tetraalkoxysilane. 3. The composition according to claim 2, wherein the tetraalkoxysilane is tetramethoxysilane or tetraethoxysilane. 4. The composition according to claim 1, wherein the silane coupling agent is a compound having an amino group. 5. The composition according to claim 1, wherein the silane coupling agent is a silane oligomer having an amino group. 6. The composition according to claim 1, wherein the film-forming resin (a) is a hydroxyl group-containing fluororesin.