JPH0812942A - Topcoating composition and method for forming topcoat - Google Patents

Abstract

PURPOSE:To prepare a topcoating compsn. for outdoor applications, capable of forming a coating film which is less likely to be soiled by incorporating an ethylenically unsatd. silicon condensate having a low degree of condensation into a reaction-curable org. coating compsn. contg. an org. solvent. CONSTITUTION:A polymer contg. an ethylenically unsatd. (modified)silicon condensate (B) having a low degree of condensation as a monomer component prepd. by reacting a low condensate of a silicon monomer represented by formula Si(OR)4 (wherein R is H or a 1-3C alkyl) and/or a modified silicon condensate having a low degree of condensation and represented by the above formula with a part of R's being substituted with a 4-24C hydrocarbon optionally contg. an ether linkage or an ester linkage, and an ethylenically unsatd. monomer having in its molecule one ethylenically unsatd. group and a functional group reactive with an SiOR group is incorporated into a reaction-curable org. coating compsn. (A) contg. an org. solvent to prepare a coating material. The compsn. (A) is selected so that the coating after curing has a contact angle, of 70 deg.C or less between the cured coating after treatment with an acid and water. A resin contg. a hydroxyl, epoxy, silanol, or hydrolyzable silyl group is pref. as a base resin for the compsn (A). The condensate (B) is pref. about di-to decamer of the monomer represented by the above formula.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a top coating composition for forming a coating film having excellent weather resistance and stain resistance, and a method for forming the coating film.

[0002]

2. Description of the Related Art Conventionally, outdoor base materials (for example, structures, displays, guard fences, appliances, machines, etc.) are coated with an outdoor paint having excellent weather resistance for the purpose of decoration or protection. ing.

At present, examples of paints used for outdoor use include polyurethane resin-based paints and fluororesin-based paints, which are exhaust gas, dust, iron powder, etc. exhausted from automobiles and the like during purging. There is a drawback that the surface of the coated object is easily soiled due to the influence of rain (acid rain), sun rays, etc. and the appearance of the coating film deteriorates.

In addition to the above-mentioned paints, silicone resin-based paints having a resin component of an alkoxysilane group-containing polymer are used as highly weather-resistant paints, but this paint is applied when the flash period becomes as long as 12 months. Although the surface of the film is less contaminated, the problem remains that the surface of the coating film is easily contaminated when the film is shorter than this.

Further, as a method for preventing surface stains,
Japanese Unexamined Patent Publication No. 61-221282 discloses a method of applying an organic solvent solution of an alkyl silicate to the surface of a molded product and a method of kneading an alkyl silicate into a thermoplastic resin molded product. However, the products obtained by these methods have a drawback that they are inferior in stain resistance retention and durability.

[0006] Further, in WO 94/06870, a topcoat paint for preventing stains is obtained by applying a coating composition prepared by blending a reaction-curable organic coating composition containing an organic solvent with an organosilicate. Compositions are disclosed. However, the one obtained by this method may have extremely poor compatibility between the organosilicate and the topcoat coating composition depending on the type of the reaction-curable coating composition, and the adhesion between the layers when the coating composition is applied repeatedly. There is a drawback that the stain resistance may be poor.

[0007]

Means for Solving the Problems The present inventors have intensively studied to solve the above-mentioned disadvantages. As a result, a coating composition obtained by blending a specific silicon compound with a curable coating composition containing an organic solvent is difficult to stain (good stain resistance).
The present invention was completed by finding out that it provides a coating film.

That is, the present invention provides a reaction-curable organic coating composition containing an organic solvent (hereinafter referred to as "reaction-curable coating composition"), which comprises (I) the following general formula Si (OR) ₄ (wherein R represents a hydrogen atom or a C _1-3 alkyl group), a low-condensation product of a silicon monomer, one ethylenically unsaturated group in one molecule, and the above-mentioned silicon low-condensation product. S
A polymer containing, as a monomer component, an ethylenically unsaturated group-containing low-condensation product of silicon obtained by reacting an ethylenically unsaturated monomer having a functional group that reacts with an iOR group

(II) A low-condensation product of a silicon monomer represented by the following general formula Si (OR) ₄ (wherein R represents a hydrogen atom or a C _1-3 alkyl group):
And a modified silicon low-condensate in which a part of R in the low-condensate is substituted with a C _4-24 monovalent hydrocarbon group (which may contain an ether bond and / or an ester bond). Ethylenically unsaturated group-containing modified silicon obtained by reacting one ethylenically unsaturated group in one molecule and an ethylenically unsaturated monomer having a functional group that reacts with the SiOR group of the above-mentioned modified silicon low-condensation product Polymer containing low condensate as monomer component

A cured coating film formed from the above composition is characterized in that the surface of the coating film after acid treatment has a contact angle with water of 70 degrees or less. The present invention relates to a method for forming a coating film, which comprises coating the composition and the top coating composition on a substrate to form a coating film, and then treating the surface of the coating film with an acid.

In the top coating composition of the present invention, the reaction-curable coating composition is formed by dissolving or dispersing in a organic solvent a curable resin composition capable of itself reaction-curing to form a crosslinked coating film structure. It is a thing.

As the reaction-curable coating composition, a cured coating film to be finally formed has a contact angle with water of 70 degrees or less after treatment with sulfuric acid water.

The reaction-curable coating composition is not particularly limited as long as it satisfies the above-mentioned conditions, and conventionally known compounds can be selected and used. Among them, a hydroxyl group-containing resin is a base resin. It is preferable to use this because it forms a coating film having excellent stain resistance in long-term outdoor baculo.

Specific examples of the hydroxyl group-containing resin include fluororesin, acrylic resin, polyester resin, alkyd resin, silicone resin and modified resins such as polyester modified acrylic resin. Among them, those using a fluorine-based resin and an acrylic resin are particularly preferable because they exhibit an excellent effect on stain resistance.

Examples of the above-mentioned hydroxyl group-containing fluororesin include hydroxyl group-containing polymerizable unsaturated monomer (a), fluoroolefin (b) and, if necessary, other polymerizable unsaturated monomer (c).
Those obtained by subjecting and to a copolymerization reaction are included.

The hydroxyl group-containing polymerizable unsaturated monomer (a)
As those having a polymerizable unsaturated double bond and a hydroxyl group which are copolymerizable with a fluoroolefin, specifically, hydroxyalkyl such as hydroxyethyl vinyl ether, hydroxypropyl vinyl ether, hydroxybutyl vinyl ether, hydroxypentyl vinyl ether and the like. Hydroxyallyl ethers such as vinyl ether, ethylene glycol monoallyl ether, diethylene glycol monoallyl ether and triethylene glycol monoallyl ether can be preferably used.

The fluoroolefin (b) has the following general formula:

Embedded image

(In the formula, R ₁ , R ₂ and R ₃ represent H, F and Cl. R ₁ , R ₂ and R ₃ may be the same or different.) Can be used. Specific examples thereof include vinyl fluoride, vinylidene fluoride, ethylene trifluoride chloride, and tetrafluoroethylene. Among them, ethylene tetrafluoride and ethylene trifluoride are preferred because a coating film having excellent durability and stain resistance can be obtained.

Other polymerizable unsaturated monomers (c) include
It has an unsaturated double bond that is copolymerizable with the fluoroolefin, and can be used by selecting from conventionally known monomers according to the required coating film performance. Specifically, for example, α-olefins such as ethylene, propylene, isobutylene, butylene-1 and the like; vinyl ethers such as ethyl vinyl ether, isobutyl vinyl ether, butyl vinyl ether, cyclohexyl vinyl ether and the like; vinyl acetate, vinyl lactate, vinyl butyrate, iso Examples thereof include fatty acid vinyl esters such as vinyl butyrate, vinyl caproate, vinyl pivalate, and vinyl caprylate; fatty acid isopropenyl esters such as isopropenyl acetate and isopropenyl propionate.

The hydroxyl group-containing fluororesin may have a carboxyl group. The carboxyl group can be introduced, for example, by subjecting a part of the hydroxyl group in the hydroxyl group-containing fluororesin to an addition reaction with a polybasic anhydride (eg, itaconic anhydride, succinic anhydride, etc.).

In addition to the above, as the hydroxyl group-containing fluororesin, a monomer (d) having a perfluoroalkyl group or a perfluoroalkenyl group at one end and an ethylenic double bond at the other end, a hydroxyl group-containing A polymer obtained by copolymerizing the radically polymerizable unsaturated monomer (e) and the other polymerizable unsaturated monomer (f) can be used.

The monomer (d) having a perfluoroalkyl group or a perfluoroalkenyl group together and an ethylenic double bond at the other end is preferably perfluorobutylethyl methacrylate or perfluorooctylethyl methacrylate. , Perfluoroisononylethyl methacrylate, perfluorodecylethyl methacrylate and the like.

Preferred examples of the hydroxyl group-containing polymerizable unsaturated monomer (e) include 2-hydroxyethyl acrylate, hydroxypropyl acrylate, 2-hydroxyethyl methacrylate and hydroxypropyl methacrylate.

The other polymerizable unsaturated monomer (f) is preferably methyl acrylate, ethyl acrylate,
Propyl acrylate, isopropyl acrylate, butyl acrylate, hexyl acrylate, octyl acrylate, lauryl acrylate, cyclohexyl acrylate,
Acrylic acids such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, hexyl methacrylate, octyl methacrylate, and lauryl methacrylate, or alkyl (C _1-18 ) esters of methacrylic acid; acrylic acid Ethylenically unsaturated carboxylic acids such as methacrylic acid: vinyl aromatic monomers such as styrene, α-methylstyrene and vinyltoluene; amide compounds of acrylic acid or methacrylic acid and derivatives thereof; acrylonitrile, methacrylonitrile and the like.

As the hydroxyl group-containing acrylic resin, the hydroxyl group-containing polymerizable unsaturated monomer (a) and / or (e), the acrylic acid or methacrylic acid (C _1-18 )
Those obtained by the copolymerization reaction with the alkyl ester of 1 or the following other radically polymerizable unsaturated monomer (g).

Examples of the other polymerizable unsaturated monomer (g) include ethylenically unsaturated carboxylic acids such as acrylic acid and methacrylic acid: vinyl aromatic monomers such as styrene, α-methylstyrene and vinyltoluene; acrylic. An amide compound of an acid or methacrylic acid and its derivative; acrylonitrile, methacrylonitrile and the like.

The above hydroxyl group-containing resin has a number average molecular weight of about 2,000 to 100,000, preferably about 5,000.
Can have a range of up to 80,000. If the molecular weight is less than about 2,000, the durability and stain resistance retention of the coating film will decrease, while if it exceeds 100,000, the compatibility with curing agents and silicon compounds will decrease and the storage stability of the paint will decrease. Is not preferred.

The hydroxyl group-containing resin has a hydroxyl value of about 20.
It may have a range of -200, preferably about 50-150. If the hydroxyl value is less than about 20, the durability of the coating film and the retention of stain resistance decrease, while if it exceeds 200, the durability, water resistance and stain resistance of the coating film decrease, which is not preferable.

The above-mentioned hydroxyl group-containing resin can be used in combination with a reactive curing agent such as an amino resin, a polyisocyanate compound or a blocked polyisocyanate compound.

Examples of amino resins include melamine, urea, benzoguanamine, acetoguanamine, steroganamin,
Methylolated amino resins obtained by reacting an amino component such as spiroganamin or dicyandiamide with an aldehyde are exemplified. Examples of the aldehyde include formaldehyde, paraformaldehyde, acetaldehyde, benzaldehyde and the like. Further, those obtained by etherifying the methylolated amino resin with an appropriate alcohol can also be used. Examples of the alcohol used for the etherification include methyl alcohol, ethyl alcohol, n-propyl alcohol, i-propyl alcohol, and n-butyl alcohol. , I-butyl alcohol, 2-ethylbutanol, 2-ethylhexanol and the like.

The above-mentioned polyisocyanate compound is a compound having two isocyanate groups in one molecule, and is an aliphatic compound such as hexamethylene diisocyanate or trimethylhexamethylene diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, cyclohexane diisocyanate. And the like, and aromatic ones such as tolylene diisocyanate and diphenylmethane diisocyanate.

As the blocked polyisocyanate compound, for example, a lactam-based blocking agent such as ε-caprolactam, an alcohol-based blocking agent such as ethanol, propanol or butanol, and an oxime-based blocking agent such as acetoxime are added to the above polyisocyanate compound. For example, the ones that are blocked by

The mixing ratio of the hydroxyl group-containing resin and the amino resin is 90 to 40% by weight of the hydroxyl group-containing resin based on the total weight of the two.
The amount is preferably 80 to 50% by weight, the amino resin is 10 to 60% by weight, and preferably 20 to 50% by weight. Outside of the above range, the stain resistance, water resistance, weather resistance, etc. of the coating film are undesirably reduced.

Further, the mixing ratio of the hydroxyl group-containing resin and the (block) polyisocyanate compound is about 0.6 to 1.5 equivalents of the isocyanate group of the (block) polyisocyanate compound to the hydroxyl group of the hydroxyl group-containing resin, preferably about A range of 0.8 to 1.2 equivalents is preferable. The mixing ratio is about 0.
When it is less than 6 equivalents, the weather resistance, stain resistance, weather resistance, water resistance and the like of the coating film are deteriorated, while when it exceeds about 1.5 equivalents, the stain resistance, weather resistance and the like of the coating film are deteriorated, which is preferable. Absent.

As the curable resin composition of the reaction curable coating composition used in the present invention, a resin containing a silanol group and / or a hydrolyzable silyl group, a hydroxyl group and an epoxy group as essential functional components other than the above-mentioned ones or Resin mixture (hereinafter, this mixture may be simply referred to as "base resin")
Can be used in which a curing catalyst is blended. This has the advantage that a coating film in which the base resin and the organosilicate or a condensate thereof are combined can be formed, so that an effect excellent in stain resistance is exhibited over a long period of time. Hereinafter, this will be described.

The hydrolyzable silyl group contained in the base resin used in the paint is hydrolyzed in the presence of water is a residue that generates hydroxy silane groups, for example alkoxy groups C ₁ ~ _5; a phenoxy group, Aryloxy groups such as tolyloxy group, paramethoxyphenoxy group, paranitrophenoxy group, and benzyloxy group; acyloxy groups such as acetoxy group, propionyloxy group, butanoyloxy group, benzoyloxy group, phenylacetoxy group, and formyloxy group, and _{-N (R 4) 2, -ON} (R 4) 2,
_{-ON = C (R 4) 2} , -NR 5 COR 4 ( wherein each R ₄ is the same or different alkyl group of C ₁ ~ _8, an aryl group (e.g. phenyl group), an aralkyl group (e.g. benzyl Etc.), R ₅ is H, C ₁ ~
_{8 represents} an alkyl group. Examples of the alkyl group include groups such as methyl, ethyl, propyl, butyl, pentyl and heptyl. ) And the like.

As the base resin, for example, a resin mixture containing three components of a hydroxyl group-containing resin (A), an epoxy group-containing resin (B), and a resin (C) containing a silanol group and / or a hydrolyzable silyl group. (Hereinafter, abbreviated as "resin"), an epoxy group-containing resin (B), a resin (C) containing a silanol group and / or a hydrolyzable silyl group, and a resin mixture (B). ) And a resin mixture (hereinafter abbreviated as “resin”) containing a hydroxyl group in either or both of the resin (C), a resin containing a hydroxyl group, an epoxy group, a silanol group and / or a hydrolyzable silyl group ( Hereinafter, it is abbreviated as “resin”) and the like.

Resin: As the hydroxyl group-containing resin (A),
Those having an average of two or more hydroxyl groups in one molecule and having a number average molecular weight of 1,000 to 100,000, preferably 3,000 to 80,000 can be used. If the average number of hydroxyl groups is less than 2, the curability (gel fraction) will be poor, which is not preferable. The number of hydroxyl groups is preferably 400 or less on average from the viewpoint of stain resistance and water resistance. If the number average molecular weight is less than 1,000, the weather resistance and stain resistance will be poor, while if it exceeds 100,000, the compatibility with other components will decrease, resulting in uneven curing and stain resistance. It is not preferable because it deteriorates the property.

As the hydroxyl group-containing resin (A), conventionally known resins can be used, but it is particularly preferable to use a vinyl polymer from the viewpoint of weather resistance, stain resistance and the like.

The vinyl polymer can be obtained, for example, by polymerizing the following hydroxyl group-containing polymerizable unsaturated monomer (h) and, if necessary, other polymerizable unsaturated monomer (i) (copolymer). ) Polymers can be used.

Examples of the hydroxyl group-containing polymerizable unsaturated monomer (h) include (h-1) to (h-5). (H-1) hydroxyalkyl vinyl ether: hydroxybutyl vinyl ether, etc., (h-2) allyl alcohol and methallyl alcohol (h-3) hydroxyalkyl ester of (meth) acrylic acid: hydroxyethyl (meth) acrylate, hydroxypropyl ( Meta)
Acrylate, hydroxybutyl (meth) acrylate, etc., (h-4) (poly) alkylene glycol monoacrylate: ethylene glycol monoacrylate, polyethylene glycol monoacrylate, etc., (h-
5) (h-1) to (h-4) and lactones (eg, ε-
Addition products such as caprolactone and γ-valerolactone).

Further, other polymerizable unsaturated monomer (i)
As, for example, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate,
Hexyl (meth) acrylate, octyl (meth) acrylate, lauryl (meth) acrylate, cyclohexyl (meth) such as such as acrylates (meth) C ₁ ~ ₂₄ alkyl or cycloalkyl esters of acrylic acid; styrene, vinyl toluene, etc. Aromatic compounds such as perfluorobutyl (meth) acrylate, perfluoroisononylethyl (meth) acrylate, perfluorooctylethyl (meth) acrylate, and other perfluoroalkyl (meth) acrylates and (meth) Acrylonitriles, olefins,
Examples include fluoroolefins, vinyl esters, cyclohexyl or alkyl vinyl ether olefins, vinyl esters, cyclohexyl or alkyl vinyl ethers, and aryl ethers.

The epoxy group-containing resin (B) has an average of 2 to 300 epoxy groups in one molecule and preferably has a number average molecular weight of 120 to 100,000, preferably 24.
0-60,000. If the number of epoxy groups is less than two on average, it is not preferable because weather resistance and stain resistance become poor. It is difficult to obtain a compound having a number average molecular weight of less than 120, while the number average molecular weight is 100,
If it exceeds 000, the compatibility with other components will be poor, and the weather resistance and stain resistance of the resulting coating film will decrease, which is not preferable.

As the epoxy group-containing resin (B), the epoxy group-containing polymerizable unsaturated monomer (j) (see, for example, JP-A No. 2-212058)
General formulas (4) to (1 described in JP-A-160879).
A homopolymer of the alicyclic vinyl monomer 8) or a copolymer with the other polymerizable unsaturated monomer (i) can be suitably used.

The resin (C) containing a silanol group and / or a hydrolyzable silyl group is, for example, γ- (meth).
Acryloxypropyltrimethoxysilane, γ (meth)
Acryloxypropyltriethoxysilane, γ (meth)
Silane compounds (k-1) such as acryloxypropyltrisilanol, γ- (meth) acryloxypropylmethyldimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2-styrylethyltrimethoxysilane, and allyltriethoxysilane. A reaction product (k-2) with the silane compound (k-1) and a trialkoxy or trihydroxysilane compound (for example, methyltrimethoxysilane, phenyltrimethoxysilane, methyltrisilanol) (for example, JP-A-2-160879). Homopolymers of polysiloxane macromonomers described in the publication, copolymers with other polymerizable unsaturated monomers (i), diphenylsilanediol, and the like can be preferably used.

The above resin (A), (B) and (C) are blended in proportions such that the resin (A) is 5 to 95 in total amount of these three components.
% By weight, preferably 20 to 80% by weight, resin (B) 95
-5% by weight, preferably 80-20% by weight, resin (C)
The range of 0.1 to 80% by weight, preferably 1 to 20% by weight is preferable in terms of weather resistance, stain resistance and the like.

Resin: As the epoxy group-containing resin (B) and the resin (C) containing a silanol group and / or a hydrolyzable silyl group, the same ones as described above can be used.

Further, in the resin, either or both of the resin (B) and the resin (C) have a hydroxyl group. As a method of introducing a hydroxyl group into the resin (B) and the resin (C), For example, it can be carried out by using the hydroxyl group-containing polymerizable unsaturated monomer (h) as an essential monomer component as a monomer component. The number of hydroxyl groups in this case is 1
It is preferable that one or more, preferably 400 or less on average be contained in the molecule. The number average molecular weight of the resin having a hydroxyl group introduced is preferably 1,000 to 100,000, and more preferably 3,000 to 60,000.

The resin (B) and (C) are blended in proportions of 5 to 95% by weight of resin (B), preferably 20 to 80% by weight of resin (C) and 95 to 95% of resin (C).
The range of 5% by weight, preferably 80 to 20% by weight is preferable from the viewpoint of weather resistance and stain resistance.

The above-mentioned hydroxyl group-containing resin (A) may be added to the resin, if desired.

Resin: The resin has an average of one or more silanol groups and / or an average of 2-40 silanol groups per molecule.
Or, a hydrolyzable silyl group, an average of 1 or more in one molecule, preferably 2 to 40 epoxy groups and an average of 2 in one molecule.
It is preferable to have ˜200 hydroxyl groups from the viewpoint of weather resistance, stain resistance and the like.

The resin is, for example, the hydroxyl group-containing polymerizable unsaturated monomer (h), the epoxy group-containing polymerizable unsaturated monomer (j), the silane compound (k-1) and / or the reaction product (k). -2), and a copolymer with other polymerizable unsaturated monomer (i) can be suitably used if necessary.

The mixing ratio of the monomers (h) to (k-2) may be such that the functional group in the resin is within the above range.

The number average molecular weight of the resin is 1,000 to
100,000, preferably 3,000-60,000
The thing of is desirable.

The hydroxyl group-containing resin (A) may be blended with the resin, if necessary.

Among the above resins, it is preferable to use a resin having excellent weather resistance and stain resistance.

The curing catalyst used in the above paint is used to accelerate the reaction of silanol groups, hydrolyzable silyl groups, epoxy groups and hydroxyl groups in the base resin, and for example, aluminum, titanium, zirconium, calcium, Metal alkoxides in which an alkoxy group is bound to a metal such as barium; metal chelate compounds in which a chelate compound capable of forming a keto-enol tautomer is coordinated with the metal alkoxides; AlCl ₃ , Al (C ₂ H ₅ )
_{2 Cl, TiCl 4, ZrCl 4} , SnCl 4, FeC
Lewis acids such as l ₄ , BF ₃ and BF ₃ : (OC ₂ H ₅ ) ₂ ; organic protic acids (metasulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, etc.), inorganic protic acids (phosphoric acid, phosphorous acid) Acid, phosphinic acid, sulfuric acid, etc.)
Protic acids; Si- such as aluminum silicate
A compound having an O-Al bond can be preferably used.
Among the above, metal chelate compounds are preferable, and further diisopropoxyethyl acetoacetate aluminum, tris (ethylacetoacetate) aluminum,
Isopropoxy bis (ethylacetoacetate) aluminum, monoacetylacetonate bis (ethylacetoacetate) aluminum, tris (n-propylacetoacetate) aluminum, tris (n-butylacetoacetate) aluminum, monoethylacetoacetate bis (Acetylacetonate) aluminum, tris (acetylacetonate) aluminum, tris (propionylacetonate) aluminum, acetylacetonate / bis (propionylacetonate)
Aluminum chelate compounds such as aluminum; titanium isochelate compounds such as diisopropoxy bis (ethylacetoacetate) titanium and diisopropoxy bis (acetylacetonato) titanium; tetrakis (n-propylacetoacetate) zirconium; Zirconium chelate compounds such as tetrakis (acetylacetonato) zirconium and tetrakis (ethylacetoacetate) zirconium are suitable.

The mixing ratio of the curing catalyst is 0.01 to 30 parts by weight, preferably 0.1 to 100 parts by weight of the base resin.
To 10 parts by weight. If the curing catalyst is less than 0.01 parts by weight, the weather resistance and stain resistance will be deteriorated, and if it exceeds 30 parts by weight, the water resistance of the coating film will be decreased, which is not preferable.

In the present invention, the organic solvent used in the reaction-curable coating composition is substantially inert to the curable resin composition, and does not dissolve or disperse the curable resin composition. Possible materials can be appropriately selected and used from conventionally known materials. Specifically, for example, hydrocarbon solvents such as toluene and xylene, ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone, ester solvents such as ethyl acetate and butyl acetate, dioxane, ether solvents such as ethylene glycol diethyl ether, butanol. , Alcoholic solvents such as propanol, and aliphatic hydrocarbons such as pentane, hexane and heptane.

The mixing ratio of the organic solvent is in the range of about 10 to 95% by weight, preferably about 20 to 90% by weight, calculated in terms of total weight with the curable resin composition.

The polymer containing the ethylenically unsaturated group-containing (modified) silicon low condensate used as the monomer component in the top coating composition of the present invention has at least one silanol group and / or silicon atom in one molecule. It is a silicon compound having a hydrolyzable group directly bonded to.

In the present invention, the silanol group means a hydroxyl group directly bonded to a silicon atom, and the hydrolyzable group directly bonded to a silicon atom means a group which produces a silanol group by hydrolysis. The hydrolyzable group is a residue that hydrolyzes in the presence of water to form a silanol group, and examples thereof include C such as methoxy, ethoxy, and propoxy.
_1-3, an alkoxyl group, an acyloxy group such as acetoxy and propionyloxy, and the like are included.

As the above-mentioned silicon compound, the general formula Si (O
R) ₄ (wherein R represents a hydrogen atom or a C _1-3 alkyl group), a low-condensation product of a silicon monomer, one ethylenically unsaturated group in one molecule, and the above-mentioned low-condensation of silicon. Thing S
The ethylenically unsaturated group-containing low-condensation product of silicon obtained by reacting an ethylenically unsaturated monomer having a functional group capable of reacting with an iOR group is optionally contained in the above (a) to (k-2).
Having an average molecular weight in the range of about 200 to about 50,000, which is obtained by a polymerization reaction with the ethylenically unsaturated monomer of the general formula Si (OR) ₄ (wherein R is a hydrogen atom or a C _1-3 alkyl group). Is a low condensate of a silicon monomer represented by the formula (1) and a part of R in the low condensate is C _4-24 1
Modified silicon low-condensation product substituted with a valent hydrocarbon group (which may contain an ether bond and / or an ester bond) and one ethylenically unsaturated group in the molecule and the above-mentioned modified silicon low-condensation product The modified ethylenically unsaturated group-containing low-condensation product obtained by reacting an ethylenically unsaturated monomer having a functional group that reacts with the SiOR group of the product (a) to (k-2) An average molecular weight of about 200 to 50 obtained by a polymerization reaction with the ethylenically unsaturated monomer of
Those in the range of 000 are included.

The low-condensation product of the above-mentioned silicon monomer is about 2-1 obtained by subjecting the above-mentioned silicon monomers to a condensation reaction.
A 00-mer, preferably about 2 to 10-mer, is suitable. Examples of the low-condensation product of the silicon monomer include "Colcoat ES40" (trade name, manufactured by Colcoat Co., Ltd., hereinafter, similarly, 1 to 10 mer of tetraethyl silicate, average of about 5 mer), "Colcoat MS51" (tetramethyl). 1 to 10 mer of silicate, an average of about 4 mer) and the like. These low-condensates made by Colcoat are generally

[0065]

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It is considered to have a structure (n is 1 to 10). In addition, in the low condensate of silicon monomer,
A part of R bonded to the silicon atom is C _4-24 (preferably C ₄
A modified silicon low-condensation product substituted with a monovalent hydrocarbon group ( _4-8 ) (which may contain an ether bond and / or an ester bond) is particularly preferably used. As the C _4-24 monovalent organic group, for example, a cyclic or linear (optionally branched) alkyl group such as butyl, pentyl, hexyl, heptyl, octyl, decyl, stearyl, and cycloalkyl, An aryl group such as phenyl, toluyl and xylyl, an aralkyl group such as benzyl (an alkyl group substituted with an aryl group) and the like are included. Further, as the organic group containing an ether bond, for example,

[0067]

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(In the formula, m is 1, 2 or 3, p is 1 or 2, and R ′ is a C _1-8 alkyl group.),

[0069]

[Chemical 4]

(In the formula, m has the same meaning as described above.)
Etc. are included. In particular,

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And the like. Further, as the organic group containing an ester bond, for example,

[0072]

[Chemical 6]

(In the formula, R ″ represents a C _1-8 cyclic or linear (optionally branched) alkyl group, an aryl group or an aralkyl group, and m has the same meaning as described above. ) Etc. are specifically included.

[0074]

[Chemical 7]

And the like. Further, as containing both an ether bond and an ester bond, for example,

[0076]

Embedded image

(In the formula, q is an integer of 2 or more, preferably 2
Is an integer of 10 and m and R ″ have the same meanings as described above.) And the like.

[0078]

[Chemical 9]

And the like. The modified silicon low condensate is
For example, a monomer in which a part of R in the silicon monomer is substituted with a C _4-24 monovalent organic group is used as a starting material, and this is subjected to a condensation reaction, or a low condensation product of the silicon monomer and C _{4 -24} alcohol (which may contain an ether bond and / or an ester bond) is subjected to dealcohol reaction to substitute a part of R of the low condensate with a C _4-24 organic group. .

The polymers of the above-mentioned ethylenically unsaturated group-containing silicon low-condensation product and ethylenically unsaturated group-containing modified silicon low-condensation product are functional groups that react with the above-mentioned SiOR groups (for example, active hydrogen groups such as hydroxyl groups). Of at least one in each molecule and an ethylenically unsaturated monomer having one ethylenically unsaturated group in each molecule and a low condensation product of a silicon monomer (including a modified silicon low condensation product) are dealcoholized. Then, a part of R of the low-condensation product is substituted with an ethylenically unsaturated group to contain an average of about 1 ethylenically unsaturated group in one molecule (including modified silicon low-condensation product). After the production of (1), an ethylenically unsaturated group-containing low silicon condensate (including modified silicon low condensate) is polymerized alone or with the above ethylenically unsaturated monomers (a) to (k-2). Obtained by reacting.

Examples of the ethylenically unsaturated monomer having the above functional group include hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate,
Hydroxybutyl (meth) acrylate, (poly) ethylene glycol mono (meth) acrylate, (poly) propylene glycol (meth) acrylate, hydroxyethyl vinyl ether, hydroxypropyl vinyl ether, hydroxybutyl vinyl ether, (poly) ethylene glycol monoallyl ether, and Examples thereof include hydroxyl group-containing ethylenically unsaturated monomers such as adducts of these with caprolactone.

In the above silicon compound, when the average molecular weight of the polymer is less than about 200, the effect of developing stain resistance is lowered, while when it exceeds about 50,000, the solid content of the coating composition is lowered, It is not preferable because the finished appearance of the film is deteriorated. The compounding ratio of the silicon compound is about 0. 0 per 100 parts by weight of the resin solid content of the reaction-curable coating composition.
The range is 5 to 50 parts by weight, preferably about 3 to 40 parts by weight. If the compounding ratio of the silicon compound is less than 0.5 parts by weight, the stain resistance of the coating film is poor, while if it exceeds about 50 parts by weight, the coating film becomes hard and defects such as cracks and gloss reduction may occur. It is not preferable. The top coating composition of the present invention may contain a colorant, a filler, a flow control agent, a plasticizer, a curing catalyst, an ultraviolet absorber and the like, if necessary, in addition to the above.

The top coating composition of the present invention is obtained by subjecting the surface of the finally formed cured coating film to acid treatment so that the surface of the coating film has a contact angle with water of 70 degrees or less, preferably 20 to 65 degrees. It comes in. For the contact angle, the coating film immediately after curing is treated (immersed) with 2.5% by weight sulfuric acid water at 20 ° C. for 24 hours,
Then, the attached sulfuric acid water is washed with water and dried, and then a drop of 0.03 cc deionized water is dropped on the surface of the coating film.
It is a value obtained by measuring the contact angle of a water drop after 3 minutes at 20 ° C. with a contact tangle meter DCAA type manufactured by Kyowa Chemical Co., Ltd. If the contact angle is greater than 70 degrees, the stain resistance and durability are poor.

The top coating composition of the present invention can form a cured coating film by applying the above-mentioned top coating composition to a substrate and then heating at room temperature or heating. When exposed to the outdoors or the like, an acid component such as acid rain causes the contact angle of water on the surface of the coating film to gradually decrease, whereby the surface of the coating film can be prevented from being soiled. Further, in the present invention, it is preferable that the coating film is previously treated with an acid before being exposed to the outdoors. By treating with an acid, the surface of the coating film can be prevented from being soiled from the initial stage.

The base material to which the top coating composition is applied is an inorganic base material such as glass, slate, concrete; metal such as aluminum, steel, zinc, tin, copper, stainless steel, zinc, tin, chromium on the steel surface. Metal base material such as metal plated with aluminum, metal surface treated with chromic acid, phosphoric acid, etc .; plastic base material such as polyethylene, polyvinyl chloride, ABS; base material such as polyvinyl chloride, polyethylene terephthalate, aluminum It can be applied to a wide range of base materials such as a tape in which a material film is provided with an adhesive or a pressure-sensitive adhesive, and a base material obtained by applying a publicly known primer intermediate coating material or top coating material to these base materials, if necessary.

The top coating composition can be applied to the surface of the substrate by means of brush coating, spray coating, roller coating, dip coating or the like. The coating amount is not particularly limited, but it is generally considered to be sufficient in the range of about 1 to 100 μm. The conditions for drying the coating film can be selected depending on the type of the top coating composition. For example, when using a base resin containing a base resin containing a hydrolyzable silyl group, a hydroxyl group and an epoxy group as essential functional group components and a metal chelate compound, at room temperature for about 24 hours or at 140 ° C. when heated. A top coating composition containing a hydroxyl group-containing resin as a base resin and a polyisocyanate compound as a crosslinking agent is dried for about 20 minutes at room temperature for about 8 hours, and a hydroxyl group-containing resin as a base resin is used as a blocked polyisocyanate. The top coating composition containing a compound or an amino resin as a crosslinking agent can be dried at about 140 ° C. for about 30 minutes.

The acid treatment of the coating film is carried out so that the surface of the coating film has a contact angle with water of 70 ° or less, preferably 20 to 65 °. The acid treatment method is not particularly limited as long as it satisfies the conditions described above. Specifically, it is preferable to treat an acidic aqueous solution having a pH of 6 or less at about 5 ° C. to 98 ° C. As the acid used here, inorganic acids such as sulfuric acid, hydrochloric acid, nitric acid and phosphoric acid are particularly preferable. It is preferable to remove the acidic aqueous solution on the treated coating film. The contact angle can be measured by the method described above.

[0088]

The topcoat coating composition of the present invention comprises a conventional method of applying an organic solvent solution of an alkyl silicate to the surface of a molded article, a method of kneading an alkyl silicate into a thermoplastic resin, and a reaction-curing type composition. Compared with the method of adding an organosilicate to an organic coating composition, it exhibits excellent effects of retaining stain resistance and durability. The reason for this is not clear, but we think as follows.

The conventional film formed by the solution of the alkyl silicate in the organic solvent causes defects such as cracks, cracks, and stripes due to the poor film-forming property of the alkyl silicate itself. Therefore, when the film is exposed to the outdoors. Rain, sun, heat,
External factors such as dust will peel off the base material, and the anti-staining effect will be lost. Further, it is possible to reduce defects such as cracks by reducing the film thickness, but it is difficult to maintain its effect for a long period of time because the film is abraded by dust etc. during outdoor baculo. Further, in the method of blending the organosilicate in the reaction-curable organic coating composition, when the compatibility of the type of the reaction-curable coating and the organosilicate is inferior, cracks may occur in the coating film and stain resistance may be obtained. There were times when it wasn't.

On the other hand, the top coating composition of the present invention comprises:
Since the coating film is composed of the above-mentioned components and the contact angle of the coating film is 70 degrees or less, the cured coating film has a layer containing a large amount of silicon compounds in the coating film surface layer or in the vicinity thereof, and the reaction does not occur inside the coating film. It is presumed that a layer having a large amount of curable coating film was formed, and as a result, the silicon compound component of the surface layer was reinforced by the reaction curable coating film, and the stain resistance retention and durability were improved.

The method of kneading an alkyl silicate into a thermoplastic resin is such that when a large amount of the alkyl silicate is blended, the properties of the thermoplastic resin are lost and the workability is deteriorated, while the workability is not lost. In the case where the compounding amount of the alkyl silicate is adjusted to the above, the one excellent in stain resistance cannot be obtained, and both are not satisfied.

On the other hand, in the top coating composition of the present invention, as described above, the surface layer is composed of the silicon compound component, and the inside thereof is composed of the reaction-curable organic coating film, and the stain resistance depends on the silicon compound component and the durability, The workability and adhesiveness have a remarkable effect of satisfying both the stain resistance and the durability by allocating the functions of the reaction-curable organic coating film. In addition, the compatibility with reaction-curable paint is
By appropriately selecting the type and / or amount of the silicon compound in the composition of the present invention, it is possible to solve the problem of compatibility with any resin.

[0093]

The present invention will be described in detail below with reference to examples. "Parts" and "%" in the examples are based on weight.

Curable resin coating composition γ-methacryloxypropyltrimethoxysilane 10.
A mixture of 0 parts, 14.2 parts of glycidyl methacrylate, 12.0 parts of 2-hydroxyethyl methacrylate, 63.8 parts of n-butyl methacrylate, and 2.0 parts of azobisisobutylvaleronitrile is subjected to a radical polymerization reaction in xylene. Resin solid content 50%, number average molecular weight 40,
To 200 parts of 000 resin tris (acetylacetonato)
Compounded with 1 part of aluminum.

Curable resin coating composition 5 parts of γ-methacryloxypropyltrimethoxysilane,
95 parts of methyltrimethoxysilane, 30 parts of deionized water,
A mixture of 98% formic acid was reacted at 100 ° C. for 8 hours to obtain a siloxane macromonomer having a number average molecular weight of 2,500.

Then, the siloxane macromonomer 1
5 parts, 3,4-epoxycyclohexyl methacrylate 20 parts, 2-hydroxyethyl acrylate 18 parts, n
50% resin solid content obtained by radical polymerization reaction of a mixture of 32 parts of butyl methacrylate, 15 parts of styrene and 4 parts of azobisisobutyronitrile in isobutyl acetate;
A mixture of 200 parts of a resin having a number average molecular weight of 8,000 and 1 part of tris (acetylacetonato) aluminum.

Curing type resin coating composition Retan 6000 White (trade name, manufactured by Kansai Paint Co., Ltd.,
Acrylic polyisocyanate curing type organic solvent paint, resin solid content 50%)

Curing type resin coating composition Campeflon HD white (trade name, manufactured by Kansai Paint Co., Ltd., fluorine polyisocyanate curing type organic solvent coating, resin solid content 50%)

Curable resin coating composition Silicotect AC (trade name, manufactured by Kansai Paint Co., Ltd.,
Acrylic silicone curing type organic solvent paint, resin solid content 50
%)

Silicon compound "Colcoat ES40" 850 g 2-hydroxyethylmethacrylate 150 g Tris (acetylacetonato) aluminum 0.1 g Hydroquinone 1 g A mixture of 53 g was deethanolized at 120 ° C. for 3 hours to give an average of 1 in 1 molecule. A silicon-containing monomer having a number of unsaturated bonds was obtained.

Next, a mixture of the above silicon-containing monomer 300 g hydroxyethyl acrylate 232 g n-butyl methacrylate 468 g azobisisobutyronitrile 30 g was dropped into 1,000 g of xylene at 100 ° C. and reacted for 8 hours to give a number average molecular weight of 15 1,000 silicon compounds, which are acrylic resins, were obtained.

Silicon Compound “Colcoat ES40” 530 g Benzyl alcohol 470 g Tris (acetylacetonato) aluminum 0.1 g A mixture of 200 g was subjected to deethanolation reaction at 160 ° C. for 6 hours to obtain a modified silicon compound. This product has 6 out of 12 ethoxy groups on average in one molecule.

[0103]

[Chemical 10]

Has been replaced by. Next, a mixture of the above-mentioned modified silicon compound 850 g 2-hydroxyethyl methacrylate 150 g tris (acetylacetonato) aluminum 0.1 g hydroquinone 1 g was subjected to 53 g deethanolation reaction at 120 ° C. for 3 hours, and an average of 1 in 1 molecule. A modified silicon-containing monomer having an unsaturated bond was obtained.

Furthermore, a mixture of the above-mentioned modified silicon-containing monomer 300 g hydroxyethyl acrylate 232 g n-butyl methacrylate 468 g azobisisobutyronitrile 30 g was added dropwise to 1,000 g of xylene at 100 ° C. and reacted for 8 hours to give a number average molecular weight of 15 1,000 silicon compounds, which are acrylic resins, were obtained.

Examples 1 to 6 Compounds of Examples 1 to 6 were obtained with the formulations (resin solids) shown in Table 1.

Comparative Examples 1 to 6 Compounds (resin solids) shown in Table 1 were obtained as Comparative Examples 1 to 6.

Preparation of Coated Plate A zinc phosphate-treated steel plate (0.8 mm thick) was coated with Epomarin primer (trademark, Kansai Paint Co., Ltd., epoxy resin-based undercoating paint) to a dry film thickness of 50 μm. After indoor drying for 1 day, Epomarine intermediate coating (trade name, Kansai Paint Co., Ltd. epoxy resin intermediate coating) is applied to a dry film thickness of 30 μm, and then indoor drying for 1 day. The substrate was prepared in line.

Then, the obtained bases of Examples and Comparative Examples were bar-coater coated to a dry film thickness of 20 μm, and then dried under the conditions of Table 1 to prepare coated plates. .

As a test plate for interlayer adhesion, a bar coater coating was applied to the above-mentioned base material of the example and the comparative example so that the dry film thickness was 20 μm, and after drying under the conditions of Table 1, the same procedure was carried out. The examples and comparative examples were applied over and dried under the conditions shown in Table 1 to prepare coated plates. The coating film performance test results are shown in Table 2.

(Note 1) to (Note 5) in Tables 1 and 2 have the following meanings. (Note 1) Drying conditions A: 140 ° C. × 30 minutes B: 20 ° C., 65% RH, dried in a constant temperature room for 7 days (Note 2) Contact angle to water: 2.5%
Treated (soaked) with 20% by weight sulfuric acid water at 24 ° C for 24 hours, then wash the adhering sulfuric acid water with water and dry it, and then add 0.03cc deionized water droplets to the surface of the coating film at 20 ° C. The contact angle of the water droplet after 3 minutes is a value measured by a contact tangle meter DCAA type manufactured by Kyowa Chemical Co., Ltd.

(Note 3) Gloss retention: (6 after outdoor bacground
0 degree specular reflectance / 60 degree specular reflectance before outdoor bacground) ×
Numerical value obtained by 100. Color difference: The color difference before and after the black color is determined by JIS Z8730.
ΔE ^* _ab was calculated based on Appearance: The coating film surface was visually observed. ◎ (No defects such as cracks, blurring, and peeling on the coating film) ○ (Some slight cracks or glossing on the coating film) △ (Things showing cracks, glossing, or peeling on the coating film) × (Coating (Remarkable cracks, glossiness, peeling on the film)

(Note 4) Interlayer adhesion: JIS K-540
0 8.5.2. 2 mm x 2 in accordance with the goggles tape method
Twenty-five mm squares were prepared, and a tape was adhered to the surface thereof to evaluate the degree of peeling of the peeled squares. No peeling ○, slightly peeled squares △, squared 1/3 or more peeled × (Note 5) Compatibility: The composition was dried on a glass plate to give a dry film thickness of 30.
The coating film was painted so as to have a thickness of μm, dried at 20 ° C. for 1 day, and the transparency of the coating film was evaluated. ◎: Good △: Cloudy

[0114]

[Table 1]

[0115]

[Table 2]

[0116]

[Table 3]

[0117]

[Table 4]

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C09D 143/02 PGL 163/00 PJK 201/10 PDP // C08F 290/00 MRY

Claims (7)

[Claims] 1. A reaction-curable organic coating composition containing an organic solvent, wherein (I) the following general formula Si (OR) ₄ (wherein R represents a hydrogen atom or a C _1-3 alkyl group). A low-condensation product of a silicon monomer, one ethylenically unsaturated group in one molecule, and S of the above-mentioned low-condensation silicon product.
A polymer containing as a monomer component an ethylenically unsaturated group-containing silicon low-condensation product obtained by reacting an ethylenically unsaturated monomer containing a functional group that reacts with an iOR group, and / or (II) the following general formula Si A low condensate of a silicon monomer represented by (OR) ₄ (wherein R represents a hydrogen atom or a C _1-3 alkyl group),
And a modified silicon low-condensate in which a part of R in the low-condensate is substituted with a C _4-24 monovalent hydrocarbon group (which may contain an ether bond and / or an ester bond). Ethylenically unsaturated group-containing modified silicon obtained by reacting one ethylenically unsaturated group in one molecule and an ethylenically unsaturated monomer having a functional group that reacts with the SiOR group of the above-mentioned modified silicon low-condensation product A coating composition prepared by blending a polymer containing a low condensate as a monomer component, wherein a cured coating film formed from this has a coating surface after acid treatment with a contact angle with water of 70 degrees or less. A topcoat coating composition characterized by being present. 2. The topcoat coating composition according to claim 1, wherein the reaction-curable organic coating composition contains a hydroxyl group-containing resin as a base resin component. 3. The topcoat paint according to claim 1, wherein the reaction-curable organic coating composition contains at least one reactive curing agent selected from amino resins, polyisocyanate compounds and blocked polyisocyanates. Composition. 4. The reaction curable organic coating composition contains a resin containing a silanol group and / or a hydrolyzable silyl group, a hydroxyl group and an epoxy group in the same molecule and a curing catalyst as a curable resin composition. The top coating composition according to claim 1. 5. A reaction-curable organic coating composition contains a silanol group and / or a hydrolyzable silyl group, a hydroxyl group and an epoxy group as essential functional group components, and at least one of these functional groups is a mixed system. 2. The topcoat coating composition according to claim 1, which contains the mixed resin and the curing catalyst present in 1. as a curable resin composition. 6. The topcoat paint composition according to claim 1, wherein the hydroxyl group-containing resin is a fluorine-based base resin. 7. A method for forming a coating film, which comprises applying the top coating composition according to claim 1 to a substrate to form a coating film, and then treating the surface of the coating film with an acid.