JPH04209678A - Base coating composition and method of forming coating film by using the same - Google Patents

Abstract

PURPOSE:To obtain a one-pack coating composition which is excellent in storage stability and workability and gives a coating film excellent in weatherability, appearance, and smoothness by using a specified vinyl copolymer and a specified catalyst as constituents. CONSTITUTION:The title composition contains a vinyl copolymer having at least two 2-oxo-1,3-dioxolan-4-yl groups of the formula in the molecule (e.g. a copolymer of 2,3-carbonatopropyl methacrylate, methyl methacrylate, styrene and n-butyl methacrylate) and at least one catalyst for the ring opening of the aforementioned groups (e.g. trimethylbenzylammonium hydroxide).

Description

[Detailed description of the invention]

[00011

[Industrial Application Field] The present invention relates to a new and useful coating composition and a coating film forming method using the same. More specifically, the present invention provides as essential film-forming ingredients:
A vinyl copolymer having a specific reactive group called 2-oxo-1,3-dioxolan-4-yl group (
1), or the vinyl copolymer (1), and a specific compound (3) having a carboxyl group and/or an acid anhydride group, especially a one-component type with excellent storage stability. The present invention relates to an extremely useful coating composition that has excellent weather resistance and smoothness in coating film appearance, and a method for forming a coating film using the same. [0002] [0002] In recent years, there has been a strong need for excellent finished appearance, mainly in the automobile industry. In response to these needs, a two-coat, one-bake finishing method, which is well known in the paint industry and the automobile industry, has been adopted. In such a method, a base coat is first applied, and after a suitable period of time during which the paint film has not dried sufficiently, a top clear coat is applied, and then baking is performed. [0003] A problem with this method is that if the interval between base coat application and clear coat is shortened, the base coat is eroded by the thinner contained in the clear coat, resulting in poor finished appearance. First, productivity deteriorates, and the thinner composition in the clear coat is limited. [0004]

[Problems to be Solved by the Invention] However, the present inventors have made extensive studies in order to meet the above-mentioned demands. In other words, the problem to be solved by the present invention is to provide a resin composition for a one-component paint that has excellent storage stability and is also excellent in weather resistance and coating film appearance such as smoothness. An object of the present invention is to provide an extremely useful resin composition for coatings, and a method for forming a coating film using the same. [00051

[Means for solving the problem] Therefore, the present inventors
As a result of intensive studies focused on the problems that the invention aims to solve as described above, we found that 2-oxo-1,3-
Vinyl copolymer containing dioxolan-4-yl group (
1) and a 2-oxo-1,3-dioxolan-4-yl group ring-opening catalyst (2), that is, a coating composition comprising the vinyl copolymer (1) as an essential film-forming component. Alternatively, it contains the vinyl copolymer (1) described above and a carboxyl group- and/or acid anhydride group-containing compound (3) as essential film-forming components, and further contains 2-oxo-1゜3.
-The coating composition also containing the dioxolan-4-yl group ring-opening catalyst (2) has excellent storage stability, and therefore,
The present invention was completed by discovering that it is possible to provide a one-component paint with good workability and to provide a coating film with excellent weather resistance and coating appearance. [0006] That is, the present invention includes at least two of the following general formula (I) in one molecule as essential components.
One or more ring-opening catalysts (
2), or to the vinyl copolymer (1) having at least two 2-oxo-1,3-dioxolan-4-yl groups in one molecule, at least two carboxyl groups in one molecule. and/or a coating composition comprising a compound (3) having an acid anhydride group and a ring-opening catalyst (2) having a 2-oxo-1,3-dioxolan-4-yl group, and use thereof The present invention aims to provide a coating film forming method. [0007] Furthermore, at least two 2 in one molecule
- A vinyl copolymer (1) containing an oxo-1,3-dioxolan-4-yl group, and a polyester resin having two carboxyl groups and/or acid anhydride groups in one molecule,
A coating composition comprising at least one compound selected from vinyl copolymers and low-molecular compounds and a ring-opening catalyst (2) having a 2-oxo-1,3-dioxolan-4-yl group; Furthermore, the present invention aims to provide a coating film forming method using the same. [0008] [0009] (However, R1, R2 and R3 in the formula each represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, which may be the same or different. ) Here, the above-mentioned vinyl copolymer (1) having at least two 2-oxo-1,3-dioxolan-4-yl groups in one molecule, which is an essential component of the present invention, includes: For example, one molecule contains one polymerizable unsaturated double bond and at least one 2-oxo-1
, a compound having a 3-dioxolan-4-yl group (
4) and other polymerizable unsaturated monomers by a conventional method, or by combining a 2-oxo-1,3-dioxolan-4-yl group and a hydroxyl group such as glyceryl carbonate. It can also be obtained by adding the compound (5) having the above to a vinyl copolymer having a functional group that reacts with the hydroxyl group. [00101 Typical functional groups that can react with the above-mentioned hydroxyl groups include isocyanate groups, acid anhydride groups, and acid chlorides. In particular, a compound (4) having both one polymerizable unsaturated double bond and at least one 2-oxo-1,3-dioxolan-4-yl group in one molecule and other polymerizable unsaturated A method of copolymerizing monomers by a conventional method is particularly recommended because it is simple. [00111 At least two 2-oxo- in one molecule
1,3-dioxolan-4-yl group-containing vinyl copolymer (1) containing one polymerizable unsaturated double bond and at least one
The compound (4) having 2-oxo-1,3-dioxolan-4-yl groups is represented by the following general formula (II); [
[0012] [0013] (However, R1, R2,
R3 and R4 each represent a hydrogen atom or a C1-C4 alkyl group, which may be the same or different. ). Specifically, 2.3-carbonate propyl (meth)acrylate, 3.4-carbonate butyl (meth)acrylate, 4.5-carbonate pentyl (meth)acrylate, 6.7-carbonate hexyl (meth)acrylate, 2 .3-carbonate propyl vinyl ether or methyl-2,3-carbonate propyl crotonate. [0014] The appropriate amount of these compounds to be used is 1 to 50 parts by weight, preferably 5 to 35 parts by weight. If the amount of IM is less than 100 parts by weight, crosslinking will be insufficient when forming a coating film, and sufficient coating performance will not be exhibited.On the other hand, if it exceeds 50 parts by weight, the coating film will be hard and brittle. The case is also unfavorable. In addition, the above-mentioned 2-oxo-1,3-dioxolane-4
-yl group (hereinafter abbreviated as cyclocarbonate group)
Examples of other vinyl monomers that can be copolymerized with the unsaturated monomer (4) having a hydroxyl group and/or a carboxyl group as a functional group are not particularly limited. It is preferable to use a monomer, and copolymerization of such a cyclocarbonate group with an unsaturated monomer having both a hydroxyl group and/or a carboxyl group can enhance the effects of the present invention. It is especially recommended because it allows [0015] Typical examples of such hydroxyl group-containing unsaturated monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 3-hydroxypropyl (meth)acrylate. or 4-hydroxyethyl (meth)
hydroxyalkyl (meth)acrylates such as acrylate; hydroxyalkyl vinyl ethers such as 2-hydroxyethyl vinyl ether or 4-hydroxybutyl vinyl ether; allyl compounds such as allyl alcohol or hydroxyethyl aryl ether; On the other hand, examples include hydroxyl group-containing unsaturated monomers to which ε-caprolactone is added. [0016] The introduction of such hydroxyl groups causes a reaction with carbonate, which induces an increase in crosslinking density, which in turn improves solvent resistance, weather resistance, and the like. Moreover, carboxyl group-containing unsaturated monomers can also be used. When such a carboxyl group-containing unsaturated monomer is used, it is particularly effective because it significantly improves the compatibility with the carboxyl group- and/or acid anhydride group-containing compound (3). [00171 The above-mentioned carboxyl group-containing unsaturated monomers used in the present invention include α, β, such as (meth)acrylic acid, maleic acid, fumaric acid, or itaconic acid; - unsaturated mono- or dicarboxylic acids; Nisel compounds of α,β-ethylenically unsaturated dicarboxylic acids such as diethyl maleate, dibutyl maleate, dibutyl fumarate or diethyl itaconate and monohydric alcohol C1-04;
Alternatively, it may be an unsaturated monomer obtained by adding an acid anhydride such as phthalic anhydride to a hydroxyl group-containing vinyl monomer such as 2-hydroxyethyl (meth)acrylate. [0018] Other copolymerizable vinyl monomers include C+ to C
Alkyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate or cyclohexyl (meth)acrylate, or (meth)acrylate having an alkyl group of 22
(Meth)acrylates such as acrylonitrile; glycidyl (meth)acrylate, methylglycidyl (meth)acrylate, (meth)acrylamide, N-alkoxymethylated (meth)acrylamide, phosphoric acid group-containing (meth)acrylate;
meth)acrylate, hydrolyzable silyl group-containing (meth)
Reactive group-containing (meth)acrylates such as acrylate; or styrene, tert-butylstyrene, α
- aromatic vinyl monomers such as methylstyrene or vinyltoluene; and fluorine-containing vinyl monomers such as tetrafluoroethylene or hexafluoropropylene. [0019] Thus, at least two 2
-Oxo-1,3-dioxolan-4-yl group-containing vinyl copolymer (1) can be prepared by known and commonly used methods such as solution polymerization method and non-aqueous dispersion polymerization method. The solution radical method is the simplest method. Examples of particularly typical solvents used here include toluene, xylene, cyclohexane, n
Hydrocarbon solvents such as hexane, octane, "Tsurpetz 100" or "Tsurpetz 150"; Ester solvents such as methyl acetate, butyl acetate, amyl acetate, ethyl ethoxyprobionate or ethoxypropionate acetate; methyl ethyl ketone, methyl isobutyl ketone , methyl amyl ketone, or cyclohexanone, and it goes without saying that these solvents may be used alone or in combination of two or more. [00201 In addition, as a radical polymerization initiator, only typical examples include azo-based initiators such as azobisisobutyronitrile, and/or peroxide-based initiators such as benzoyl peroxide. It is a drug. Furthermore, various chain transfer agents such as lauryl mercaptan, octyl mercaptan, 2-mercaptoethanol, octyl thioglycolate, 3-mercaptopropionic acid, or α-methylstyrene dimer can be used as a molecular weight regulator, if necessary. [00211 The number average molecular weight of the vinyl copolymer (1) thus obtained is preferably within the range of 800 or more and 50,000 or less from the viewpoint of coating film performance or coating workability. Next, the carboxyl group and/or acid anhydride group-containing compound (3), which is an essential component of the present invention, is made of vinyl copolymers, polyester resins, and low-molecular compounds having such specific functional groups. At least one selected from the group can be used. [0022] Specifically, first, as the vinyl copolymer, for example, a carboxyl group-containing unsaturated monomer and/or an acid anhydride group-containing unsaturated monomer may be copolymerized with other materials such as those described above. It may also be obtained by copolymerizing with an unsaturated monomer. As such carboxyl group-containing unsaturated monomers, those mentioned above can be used. [0023] In addition, to exemplify only particularly typical unsaturated monomers containing acid anhydride groups, monomers containing acid anhydride groups and unsaturated groups, such as maleic anhydride and itaconic anhydride, monomers with Furthermore, other unsaturated monomers that can be copolymerized with the carboxyl group-containing unsaturated monomer and/or acid anhydride group-containing unsaturated monomer include the above-mentioned cyclocarbonate group-containing unsaturated monomer. Those mentioned as polymerizable unsaturated monomers can also be used. [00241] Next, as the carboxyl group-containing polyester resin, for example, one obtained by reacting an acid component excessively with a polyhydric alcohol, or one obtained by reacting a hydroxyl group-containing polyester resin with an acid anhydride compound, etc. The following are particularly representative. Specific examples of the polyester resin include polyvalent carboxylic acids such as phthalic acid, hexahydrophthalic acid, isophthalic acid, adipic acid, maleic acid, or dimer acid, and ethylene glycol, propylene glycol, neopentyl glycol, or Examples include those obtained by condensing polyhydric alcohols such as trimethylolpropane using known and commonly used methods. [0025] Furthermore, it can be obtained by adding an acid anhydride group-containing compound such as trimellitic acid to the hydroxyl group in the polyester resin, and it can also be obtained by reacting under conditions such that the polycarboxylic acid is in excess. . Next, only typical examples of carboxyl group-containing low-molecular compounds include adipic acid, phthalic acid, isophthalic acid, and dimer acid, which contain two carboxyl groups in one molecule. There are no particular limitations on the compound as long as it contains more than one. [0026] On the other hand, to exemplify only particularly representative low-molecular compounds containing acid anhydride groups, trimellitic acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, het's acid anhydride, himic anhydride, maleic anhydride. Examples include acids, itaconic anhydride, pyromellitic anhydride, glycerol tris(trimelitate), and ethylene glycol di(trimelitate). [00271] Next, to explain the ring-opening catalyst (2) for the cyclocarbonate group described above, which is an essential component of the present invention, it is an essential component for the decarboxylation reaction from the cyclocarbonate group. Among them, to exemplify only the most representative ones, quaternary ammonium salts such as tetramethylammonium fluoride, trimethylhendyl ammonium hydroxide, 2-hydroxypyridine or trimethylbenzylammonium methoxide; phosphoric acid, p - acid catalysts such as toluenesulfonic acid or dimethyl sulfuric acid; or carbonates such as calcium carbonate. [00281 The appropriate amount of the cyclocarbonate group decomposition catalyst to be used is within the range of 0.01 to 5 parts by weight based on 100 parts by weight of the solid content of the vinyl copolymer described above. The amount used is 0.01 when baking for about 20 minutes at a temperature range of 120 to 160°C.
If the amount is less than 5 parts by weight, the crosslinking reaction will not proceed sufficiently, while if it exceeds 5 parts by weight, problems will occur with the storage stability of the paint and the water resistance of the cured coating will be poor. Become. [0029] Furthermore, an epoxy group ring-opening catalyst can be used to promote the reaction between the epoxy group and the carboxyl group generated by the decarbonation reaction of the cyclocarbonate group, and as such a component, an epoxy group ring-opening catalyst can be used to For promotion, preference is given to using commonly used basic catalysts. Examples of such basic catalysts include the above-mentioned quaternary ammonium salts and quaternary phosphonium salts, as well as tertiary organic phosphorus compounds represented by triphenylphosphine. The amount of the epoxy ring-opening catalyst used is preferably 5 parts by weight or less based on 100 parts by weight of the solid content of the vinyl copolymer (1). [00301 The coating composition of the present invention obtained in this manner may also contain known and commonly used additives such as a leveling agent and an ultraviolet absorber, as well as organic pigments, inorganic pigments, or metal pigments. Further, the composition of the present invention may contain a known and commonly used plasticizer, or a polyester resin, and further, polyethylene waxes, celluloses, crosslinked beads, fine particles of cross-linked beads, or inorganic fine particles. A fluidity modifier or the like may also be added. [00311 Furthermore, the coating composition of the present invention has two coats, one
It can be used as a base coat when forming a coating film using the beta method or the two-coat, two-bake method. At this time, the paint composition for clear coat is not particularly limited, and as long as it forms a paint film,
It can be anything. Typical examples of the clear coat composition include a hydroxyl group-containing resin and a melamine resin, a hydroxyl group-containing resin and a polyisocyanate, a carboxyl group-containing resin and an epoxy group-containing resin, or a hydrolyzable silyl group-containing resin. Furthermore, there are those in which the base coat composition of the present invention is used as a clear coat, and those in which two or more of these are used in combination. [0032]

[Examples] Next, the present invention will be specifically explained using reference examples, examples, and comparative examples. In the following, all parts and percentages are based on weight unless otherwise specified. Reference Example 1 [Preparation example of cyclocarbonate group-containing vinyl copolymer (1)] 500 parts of xylene and n-butanol were added to a four-bottle flask equipped with a thermometer, a cooling tube, a stirrer, and a nitrogen gas introduction tube. 300 parts of 2,3-carbonate propyl methacrylate was charged and the temperature was raised to 120°C.
0 parts, 200 parts of methyl methacrylate, 2 parts of styrene
a mixture of 200 parts of xylene, 10 parts of azobisisobutyronitrile (AIBN) and 10 parts of tert-butylperoxy-2-ethylhexanoate. was added dropwise over a period of 5 hours at the same temperature, and even after the completion of the dropwise addition, the same temperature was maintained for 7 hours to react. ) was obtained as ST. Hereinafter, this will be abbreviated as resin (A-1). Reference Example 2 (same as above) As a monomer mixture, 250 parts of 2,3-caponate butyl acrylate N, 150 parts of styrene, 350 parts of isobutyl methacrylate, 150 parts of 2-ethylhexyl methacrylate, 2.3- A resin with a nonvolatile content of 50.6% and a viscosity of Z was obtained in the same manner as in Reference Example 1, except that a mixture of 50 parts of carbonate propyl acrylate and 50 parts of methacrylic acid was used. Ta. Hereinafter, this will be abbreviated as tree MW (A=2). Reference example 3 [Carboxyl group-containing acrylic resin (3)
Preparation Example] As a monomer mixture, 300 parts of acrylic acid, 300 parts of styrene and 400 parts of n-butyl methacrylate were used, and as an initiator, 15 parts of AIBN, tert-
A resin with a nonvolatile content of 50.2% and a viscosity of O was obtained in the same manner as in Reference Example 1, except that 70 parts of butyl per-2-ethylhexanoate was used. Hereinafter, this will be abbreviated as resin (B-1). Reference Example 4 [Example of preparation of carboxyl group-containing polyester resin] To 500 parts of Plaxel 308J [caprolactone polymerized polyol manufactured by Daicel Chemical Co., Ltd.], 87 parts of phthalic anhydride, 100 parts of xylene, and 50 parts of butyl acetate were added. After the reaction was carried out at 120° C. for 2 hours, a resin solution with a nonvolatile content of 80% and a viscosity of Q was obtained. Hereinafter, this will be abbreviated as resin (B-2). Examples 1 to 5 and Comparative Examples 1 to 3 Using the resins obtained in Reference Examples 1 to 4, coating compositions of the present invention were obtained according to the blending composition ratios shown in Table 1. Furthermore, the performance of coating films obtained by a 2-coat, 2-bake finish or a 2-coat, 2-base finish using the coating composition of the present invention as a base coat was evaluated. The results are shown in the same table. [0033]

[Table 1] [0034] The footnotes to the table are as follows. The types of pigments used are as follows. 716ONS: Aluminum flakes manufactured by C Toyo Aluminum Co., Ltd.] MA-100: [Carbon black manufactured by Mitsubishi Kasei Corporation] CR-93: [Titanium oxide manufactured by Ishihara Sangyo Co., Ltd.;
"Tie Bake CR-9-93J" NS2 [[First Gen Blue (F
a stgen Blue) NKJY
: [Fast Gen Blue (made by the same company)
gen Red) YJ) The paint made of acrylic resin/melamine resin used in Comparative Example 3 was
J [hydroxyl group-containing acrylic resin manufactured by Dainippon Ink and Chemicals Co., Ltd.] and [Super Beckamine L-117-6]
04 (butyl etherified melamine resin manufactured by the same company),
It consists of a mixture in a ratio of 70:30 (solid content weight ratio). [0035] In addition, the clear paint A includes [Acrydic 44-179J (a hydroxyl group-containing acrylic resin manufactured by the same company) and "Super Beckamine L-117-60".
J (butyl etherified melamine resin manufactured by the same company),
It consists of a mixture of 70:30 (solid content weight ratio). Furthermore, clear paint B is
Acridic BU-955J (hydroxyl group-containing acrylic resin manufactured by the same company) and [Parnock DN-95]
0J [polyisocyanate resin manufactured by Dainippon Ink Chemical Co., Ltd.] in an equivalent ratio of ○H/NGO=1/1. [0036] Only in Example 4, a two-coat, two-bake finish was used to form a coating film, and in all other cases, a two-coat, one-bake finish was used to form a coating film. The baking conditions were 140° C. for 20 minutes in all examples. [0037]

[Effects of the Invention] The coating composition of the present invention and the coating finishing method using the same have excellent storage stability as a one-component coating, and therefore have good workability. Of course, the coating film obtained by the coating finishing method of the present invention is excellent in weather resistance and coating appearance, especially smoothness. [0038] Therefore, it can be said that the coating composition of the present invention and the coating finishing method using the same open up a new direction in automobile coating.

Claims (6)

[Claims] Claim 1: At least two of the following general formula in one molecule [
2-oxo-1,3-dioxolane represented by
characterized by containing a vinyl copolymer (1) having a 4-yl group and a ring-opening catalyst (2) having one or more 2-oxo-1,3-dioxolan-4-yl groups; Paint composition. [Chemical formula 1] ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) (However, R^1, R^2 and R^3 in the formula are
Each represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, which may be the same or different. ) Claim 2: A vinyl copolymer (1) having at least two 2-oxo-1,3-dioxolan-4-yl groups represented by the following general formula [I] in one molecule; a compound (3) having at least two carboxyl groups and/or acid anhydride groups; and a ring-opening catalyst (2) of a 2-oxo-1,3-dioxolan-4-yl group. , paint composition. [Chemical formula 2] ▲There are mathematical formulas, chemical formulas, tables, etc.▼[I] (However, R^1, R^2 and R^3 in the formula are
Each represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, which may be the same or different. ) 3. The vinyl copolymer (1) having at least two 2-oxo-1,3-dioxolan-4-yl groups in one molecule is an acrylic copolymer. Coating composition according to item 1 or 2. 4. At least two 2-
The coating composition according to claim 1 or 2, wherein the vinyl copolymer (1) having an oxo-1,3-dioxolan-4-yl group is a fluoroolefin copolymer. 5. When forming a coating film using a 2-coat 1-bake method or a 2-coat 2-bake method, as a base coat,
A method for forming a coating film, comprising using the coating composition according to claim 1 or 2. [Claim 6] When forming a coating film using a two-coat one-bake method or a two-coat two-bake method, as a base coat,
A method for forming a coating film, comprising using the coating composition according to claim 1 or 2.