JPH0286671A - Thermosetting coating composition - Google Patents

Abstract

PURPOSE:To form a coating film having excellent scuffing resistance, gloss, gasoline resistance, hot water resistance and weathering resistance by mixing a specified acrylic copolymer with a polyisocyanate. CONSTITUTION:10-60wt.% at least one hydroxylated (meth)acrylate of formula I [wherein R<1> is H or methyl; R<2> is an organic substituent of formula II, III or IV (wherein R<3-7> are each H or methyl; l is 2-5; j is 2-10; k is 1-7; and m is 1-3)] is mixed with 0.1-10wt.% at least one carboxylated, sulfonated phosphated vinyl monomer, 15-60wt.% (meth)acrylate of formula V (wherein R<8> is H or methyl; R<9> is a 4C or higher hydrocarbon substituent), and 0-50wt.% at least another copolymerizable vinyl monomer to obtain an acrylic copolymer (A) of an OH number of 70-180mgKOH/g, an acid number of 0.5-30mgKOH/g, a glass transition point of -50 deg.C to 70 deg.C. Component A is mixed with a polyisocyanate compound (B) in such an amount that the equivalent ratio of the OH groups of component A to the NCO groups of component B is 1:0.5-1.5.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Fields of Application] The present invention is applicable to paint films with high cosmetic properties and excellent film performance such as paint films on automobile bodies, such as scratch resistance, sulfite resistance, and outdoor use. @A thermosetting type that is used in fields that require excellent gloss characteristics under dew conditions, and can also be applied to plastics with low heat distortion temperatures? The present invention relates to an Ili coating composition. To explain in more detail, the present invention employs a so-called two-coat/one-bake coating method in which a base coat paint containing a colorant is applied, then a clear coat paint is overcoated, and then heated and cured to obtain a laminated film. Related to clear coat paints (coating compositions) used for applications, or solid color paints (coating compositions) containing organic or inorganic pigments or glitters, which are usually applied in a one-coat/one-bake method. It is.

[Prior Art] In the painting of automobile bodies, after electrodeposition coating and intermediate coating, in the case of so-called metallic cars, a base coat paint containing coloring pigments, metallic pigments, mica, etc. is applied. The so-called 2-coat, 1-bake method, in which the top clear coat paint is overlaid using a wet-on-wet method and both paints are heated and cured at the same time, is also used in the case of solid color cars. After coating, a solid color paint containing organic pigments or inorganic pigments and auxiliary additives such as photoresist is applied and cured by heating, which is the one-coat/one-hook method that is generally used.

In recent years, the durability of paint films has become a problem in the automobile industry, particularly the deterioration of the appearance of paint films due to scratches. Painted surfaces finished using 2 coats/1 block method using 4 colors of base coat paint such as black, navy blue, and red and clear coat 214, or similarly finished using 1 coat/1 block method. On the surface of the dark solid color 28, scratches caused by contact with car wash brushes, abrasives such as compound and wax, sand particles thrown up during driving, and foreign objects are easily noticeable. In particular, there is a strong desire both domestically and internationally to solve the problem of scratches caused by car wash brushes in automatic car wash machines.

As a solution to this problem, it has been proposed to provide scratch resistance by applying a heart coat using UV hardening oven silicone paint.
It has been difficult to form a coating film with a good balance of repairability and weather resistance.

[Problems to be Solved by the Invention] It is an object of the present invention to improve the clear coat paint in a two-coat, one-bake system, or the solid color paint film in a one-coat, one-bake system. By using a resin component that can form a specific acrylic thermosetting coating as a resin component in the solid color paint that makes up the coating, the weather resistance, water resistance, and solvent resistance of conventional urethane-acrylamino thermosetting coatings can be improved. An object of the present invention is to provide a coating composition that maintains properties and forms a coating film with excellent scratch resistance and sulfite resistance.

[Means for Solving the Problems] The above object is to apply the ff composition of the present invention, that is, a clear coat paint in a 2-coat, 1-area painting system, or a coloring material in a 1-coat, 1-area painting system. Provided is a thermosetting coating composition characterized by containing a specific acrylic copolymer (A) and a polyisocyanate compound (B) as a binder resin component constituting a paint for a solint color coat containing a pigment. This is achieved by

To explain in more detail, the present invention provides (1) (a) at least a hydroxyl group-containing (meth)acrylic acid ester represented by the following general formula (I) 10 to
60% by weight, I CI+2=C-C-0-R'
(I) (wherein R' is a hydrogen atom or
represents a methyl group, and R2 is represented by the following formula (II), (I
ll) or (IV) 11! l i
I! ! ! represents violence. ) R30 C1l, C11-0-(C-(CL), l!-0)4-
II (II) (wherein, R3, R4, R5
, R6 and R7 represent a hydrogen atom or a methyl group,
1 is an integer from 2 to 5, j is an integer from 2 to lO, and k is an integer from 1 to 10.
m represents an integer of 7, and m represents an integer of 1 to 3, respectively. ) (b) Vinyl carmer containing at least one type of carboxyl group, sulfonic acid group or phosphoric acid group 0.1 to 1
0% by weight (C) - (meth)acrylic acid ester represented by formula (V) 15-60% by weight (wherein, R6 represents a hydrogen atom or a methyl group, R9
represents a hydrocarbon substituent having 4 or more carbon atoms), and (d) at least one other copolymerizable vinyl group! #
0 to 50% by weight, obtained by copolymerizing, the hydroxyl value is 70 to 180mg
7g of KOH has an acid value of 0.5 to 30mg KOH/
containing an acrylic copolymer (A) having a glass transition temperature of 150°C to 70°C and (2) a polyisocyanate compound CB), and containing OH groups present in the acrylic copolymer (A). equivalent of (
×) and the equivalent of NCO group in the polyisocyanate compound (
(7) The ratio X/Y is X10. s to l/1.5.

Acrylic copolymer (A) used in the coating composition of the present invention
is obtained by copolymerizing each of the heptamers of (a), (b), (c), and (d), and among these, (
Examples of the hydroxyl group-containing (meth)acrylic ester represented by formula (I) in a) include 2-hydroxypropyl (meth)acrylate or 2-hydroxyethyl (
ε-caprolactone or γ- to meth)acrylate
Adduct of butyrolactone, 2-hydroxypropyl (meth)acrylate or 2-bitroxyethyl (meth)
Ethylene oxide or propylene oxide adducts to acrylates, 2-hydroxyethyl (meth)
Examples include dimers or trimers of acrylate or 2-hydroxypropyl (meth)acrylate.

Specifically, Plaxel FMI, Plaxel FM2, Plaxel F to 2, and Plaxel FM6 manufactured by Daicel Chemical ■
: Blenmar PE-90, Blenmar PE-350, Blenmar PP100O manufactured by NOF ■, Acrylic oligomer) IE-20, ) IP-20 manufactured by Nippon Shokubai Chemical ■
and Taunt 100 manufactured by Union Carbind.

The amount of the hydroxyl group-containing (meth)acrylic ester (a) used is 10 to 60% by weight based on the total weight of each of (a), (bl), (c), and (d).

If it is less than 10% by weight, the scratch resistance of the coating film will be insufficiently improved, and if it exceeds 60% by weight, the water resistance of the coating film will decrease, which is not preferable. A more preferable range is 15 to 40% by weight.

The carboxyl group, sulfonic acid group, or phosphoric acid group-containing vinyl carmer (b), which is the second component used in the production of the acrylic copolymer (A), contains one or more carboxyl groups,
Examples of the jllI-mer containing a carboxyl group and a jllLi-form containing a sulfonic acid group or a phosphoric acid group include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid monomethyl ester, and itaconic acid monomethyl ester. There are butyl ester, monomethyl maleate, monobutyl maleate, and monooctyl maleate. Contains a sulfonic acid group (
. Examples include Light Ester PM manufactured by Kyoei Yushi ■. The amount of these acidic substituent-containing vinyl monomers (b) used is:
(a), (b), (c), (d) 01 to 10% based on the total weight of each 1,000 pieces.

Specific examples of the (meth)acrylic acid ester represented by the general formula (V) described in section (1) (C) above include:
n-butyl (meth)acrylate, i-butyl (meth)
Acrylate, t-butyl (meth)acrylate, 5e
c-butyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, 2
-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate,
Examples include cetyl (meth)acrylate and stearyl (meth)acrylate. (1) Described in (C) (
Meth)acrylic acid ester is an essential component from the viewpoint of cosmetic properties, weather resistance, and towability of the coating film, and if the amount used is less than 15% by weight based on the total weight of each monomer, the cosmetic properties and weather resistance will be reduced. etc., the paint film performance is not balanced, and on the other hand, 60
Exceeding this percentage by weight is undesirable because solvent resistance decreases.

Examples of the other copolymerizable vinyl monomers in item (1) and (d) above include styrene, α-methylstyrene, styrene derivatives such as vinyltoluene; acrylonitrile;
Polymerizable unsaturated nitriles such as methacrylonitrile; vinyl esters such as vinyl acetate and vinyl propionate; N-alkoxy substituted amides such as N-methoxymethyl (meth)acrylamide and N-butoxymethyl (meth)acrylamide; ; glycidyl (meth)acrylate,
(Meta)allyl glycidyl ether, metaglycidyl (
Epoxy group-containing monomers such as meth)acrylic acid esters, basic compounds such as dimethylaminoethyl (meth)acrylic acid, etc. Mention may be made of meth)acrylic acid esters, which are used in the range of 0-50% by weight, based on the total weight of each mass.

That is, glass rolling BtF of the acrylic copolymer (A) produced within a range that does not impair the scratch resistance, which is a feature of the present invention.
It is used so that the A degree is 150°C to 70°C.

Monomers (a), (bl, (c) and (d) used in the production of the above acrylic copolymer (A))
The type and amount of the obtained acrylic copolymer (A)
hydroxyl value is 70-180mg KOH/g, acid value is 0
．． 5 to 30 mg KGI (/3) should be selected so that the glass transition temperature Tg is -50 to 70 degrees Celsius.The glass transition temperature of the acrylic copolymer is the T
It can be calculated from g using the following formula.

If the hydroxyl value is less than 7OH1g KOH/g, the crosslinking density of the cured coating film will be low and solvent resistance and water resistance will be reduced. On the other hand, if it exceeds 180+ng KOH/g, the viscosity of the resin solution becomes high, which reduces the cosmetic properties of the coating film, makes the coating brittle, and reduces flexibility, which is not preferable. If the amount of oxidation is less than 0.5 mg KOH/g and 7 g of OH, the crosslinking reaction rate with the polyisocyanate compound will be slow, resulting in decreased water resistance and solvent resistance, and if it exceeds 30 mg KOH/g, the pot life of the paint will be shortened. This is not desirable. In addition, if the Tg is less than 150℃, the solvent resistance of the coating film will decrease;
Exceeding this is not preferable because the scratch resistance decreases.

Acrylic copolymer (A) is obtained by polymerizing each of the above-mentioned polymers.
Any known method such as a solution polymerization method, a bulk polymerization method, an emulsion polymerization method, etc. can be used as a method for obtaining the polymer, but a solution polymerization method is particularly preferable. In the case of solution polymerization, the mixture of monomers is copolymerized in the presence of an organic solvent and a polymerization initiator. The organic solvents used are isopropyl alcohol, lobetanol, toluene, xylene, and Tsurupetz#.
100 (aromatic petroleum derivative manufactured by Esso), and the polymerization initiator may be a commonly used polymerization initiator such as azobisisobutyronitrile, benzoyl peroxide, or cumene hydroperoxide.

Also, if necessary, 2-mercaptoethanol, n-octylmercabutane, etc. can be added to the SR! 3 moving agents can be used.

The clear coat paint and solid color paint in the present invention contain a polyisocyanate compound (Bl) as a curing agent in order to satisfy the quality performance in the automotive paint, which is the main application. A polymer is a compound containing two or more evacuated or blocked isocyanate groups in one molecule, and specifically includes aliphatic diisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, and trimethylhexane diisocyanate: isophorone diisocyanate, 44 - Alicyclic diisocyanates such as methylene bis(cyclohexyl isocyanate); aromatic diisocyanates such as xylylene diisocyanate and 1-lylene diisocyanate; Polyhydric alcohol adduct; low molecular weight polyester resin having a functional group that reacts with an isocyanate group, or adduct of water and polyisocyanate, biuret body; polymer of diisocyanates; known materials such as lower monohydric alcohols and methyl ethyl ketone oxime The isocyanate groups in the polyisocyanate are blocked with a blocking agent. If the Y equivalent ratio X/Y is less than 1/1.5, the coating film will become brittle and the weather resistance will decrease.On the other hand, if X/Y exceeds tlo, s, the crosslinking density of the coating film will decrease. This is not preferable because the solvent resistance and water resistance decrease.The more preferable usage amount of the polyisocyanate compound (B) is that the above-mentioned X/Y is in the range of 1108 to 1/1.2. A tin-based curing accelerating catalyst such as dibutyltin dilaurate may also be used.If desired, the coating composition (clear coat paint) of the present invention may contain an alkyl etherified melamine resin (C) and an acrylic copolymer. Union (A) and polyisocyanate compound (B)
When the total amount is 100 parts by weight, it may be added in the range of 0 to 30 parts by weight. As a specific example of alkyl etherified melamine resin, aminotriazine is methylolated,
Examples include those obtained by alkyl etherification with cyclohexanol or an alkanol having 1 to 6 carbon atoms, and more specific examples include butyl etherified melamine resin, methyl etherified melamine resin, and methylbutyl mixed melamine resin. Specific examples of butyl etherified melamine resins include Kneepan 2QSE (manufactured by Mitsui Toatsu Chemical Co., Ltd.) and Super Beckamine G-821 (manufactured by Dainippon Ink Chemical Co., Ltd.), and examples of methyl etherified melamine resins include Seitul 303. However, examples of methylbutyl mixed melamine include Cytsuru 235 and Cytsl 23B (both manufactured by Mitsui Suyanamide ■).

In addition, in order to accelerate the curing of the melamine resin, sulfonic acid catalysts such as Naicure 155 and Naicure 3 are used.
525, Naicure 5225 (manufactured by Ueki Kaseiwa), and Catalyst eooo (manufactured by Mitsui Toatsu Chemical Co., Ltd.) can be used. In addition, when preparing a paint, that is, using the coating composition of the present invention, if necessary, use Plaxel 20, a polycaprolactone polyol, manufactured by Daicel Chemical Co., Ltd.
8 and Plaxel 220, or a reactive diluent such as Union Carbide's Tone D-190 or Tone D-225.

(1) An acrylic copolymer (A) consisting of components (a) to (1) fd) and a polyisocyanate compound (B)
), when used, the coating composition containing 2
When used as a coat/l-bake type clear paint, after adding an appropriate surface conditioner and anti-sagging agent as additives, it is diluted with an organic diluting solvent to an appropriate viscosity, and then used for painting. In addition, when used in solid color paints, inorganic pigments such as titanium oxide, talc, red iron, carbon black, quinacridone,
Colored by dispersing organic pigments such as cyanine blue,
After adding additive U agent such as M material anti-settling agent, it is diluted in the same way and painted and baked in one coat and one bake.

Other ingredients such as UV absorbers and antioxidants can be added. Further, specific examples of the above-mentioned 131M diluent include xylene, Tsurupetz #100, Tsurupetz #150, (aromatic petroleum conductor manufactured by Esso),
Ketone-based 2-heptanone (Eastman Co., Ltd.) is exemplified.
When used as a clear layer of a baked paint film, it is used together with the clear paint.

A known thermosetting paint system can be used as the base paint, and examples of the resin system serving as a vehicle for the base paint include a thermosetting acrylic melamine resin system and a thermosetting acrylic urethane resin system.

For example, in the case of an acrylic urethane resin-based hair coat paint, a film-forming acrylic resin with a functional group that reacts with a polyisocyanate compound, a volatile organic liquid diluent, and a cure dissolved in the organic liquid diluent are used. A composition consisting of a polyisocyanate compound as an agent,
Brightening agents such as aluminum paste, mica, and var;
Coloring pigments such as titanium oxide, carbon black, and quinacridone, resins other than acrylic resins such as epoxy resins, and cellulose resins are selected as necessary, and are added using a numerical compounding method.

EXAMPLES Hereinafter, the present invention will be specifically explained using examples. Note that "part r" in the examples means parts by weight.

In a reaction vessel equipped with a stirrer, temperature controller, and condenser, 50 parts of toluene and 10 parts of methyl isobutyl ketone were added.
I prepared a section. The contents of the reaction vessel were heated while stirring to raise the temperature of the inner hot water to 100°C. Next, 101.5 parts of a solution consisting of 5 parts of styrene, 2 parts of methacrylic acid, 35 parts of methyl methacrylate, 46 parts of ethyl acrylate, 12 parts of 2-hydroxyethyl acrylate, and 1.5 parts of benzoyl peroxide were added dropwise over 4 hours. A solution consisting of 0.6 parts of benzoyl peroxide and 20 parts of toluene was added dropwise over 30 minutes. The reaction solution was further stirred and heated at 100° C. for 2 hours to increase the conversion rate to resin, and then 20 parts of toluene was added to terminate the reaction. The obtained acrylic copolymer solution (nonvolatile content 50%) was coated with an acrylic resin face (D
).

The weight average molecular weight of this acrylic copolymer was measured by gel permeation chromatography.
It was 50,000.

Preparation of base coat paint Example: Reference example) Put the amounts of each material shown in Table 1 above into a stainless steel container, stir thoroughly, then adjust the viscosity with a diluent mixed solvent, and use base coat paint B-1. B-2 was manufactured. All numerical values other than viscosity in the table represent parts by weight.

Contained in clear coat or solid color paint Table 1 *1) Manufactured by Degussa Black pigment *2) Butylated melamine resin (manufactured by Mitsui Toatsu) Non-volatile content 60% *3) Polyisocyanate compound (Japanese polyurethane interior) Non-volatile 100% Composition of mixed solvent for dilution *4) Aromatic petroleum derivatives manufactured by Esso Co., Ltd. A polymerization reaction was carried out using the following procedure for each of the six types of mixtures having the compositions shown in Table 2. Taking the manufacturing method for P-1 as an example, first, 53.3 parts of Solhetsuso #100 (manufactured by Esso) was charged into a reaction vessel equipped with a stirrer, temperature control device, condenser, and monomer dropping device, and the mixture was stirred while stirring. Heating increased the temperature to 140°C. Next, 1 part of azobisisobutyronitrile and 2 parts of t-butylperoxyisopropyl carbonate were added to 100 parts of each of the 1,000-mer mixtures listed in Table 2, and the mixture was continuously added dropwise using a dropping device, and after the completion of the dropping, +40 t. The reaction mixture was heated and then 0.5 part of azobisisobutyronitrile was continuously added little by little.

After further heating and stirring at 140° C. for 1 hour to increase the conversion rate to resin, 13.3 parts of n-butyl acetate was added to terminate the reaction. Hereinafter, polymerization reactions were carried out for P-2 to P-6 in the same manner as for P-1.

The hydroxyl value and acid value of each acrylic copolymer obtained, as well as the viscosity and nonvolatile content of the copolymer solution, were as shown in Table 2. In addition, acrylic copolymer solutions P-2 and P-6
Regarding coating film formation and its evaluation, Bonderite #144 dull copper plate (Japan Test Panel■!
Then apply cationic electrodeposition paint for automobiles and heat to 180℃.
Bake for 30 minutes. Next, an amino alkyd intermediate paint was applied, and after baking at 160° C. for 30 minutes, the coating film was sanded and dried.

In the case of 2 coats/1 coat of Examples 1 to 6 and Comparative Examples 1 to 4, metallic type, the base coat paints (B-1, B-2) listed in Table 1 and The clear coat paints listed in Table 3 were coated in combinations shown in Table 3 using a wet-on-wet method. This overcoating was performed as follows. First, a base coat paint was applied onto the intermediate coat film to a dry film thickness of 15 to 30 μm, and after being left for 5 minutes, a clear coat paint was applied to a dry film thickness of 30 μm. The undried overcoated coating film was left at room temperature for 10 minutes, and then cured for 25 minutes at the baking temperature shown in the table to form a coating film.

In the case of the white thread solid color coat paints of Example 7 and Comparative Example 5, after completing the intermediate coating process, one coat of white paint was applied, and after leaving the undried paint film at room temperature for 10 minutes, the coatings listed in the table were applied. A coating film was formed by baking at a baking temperature of 25 minutes.

As is clear from the results shown in Table 4, the coating films obtained in Examples exhibit excellent performance in terms of gloss, scratch resistance, hardness, gasoline resistance, hot water resistance, weather resistance, etc. . Moreover, in the case of the comparative example, the abrasion resistance, solvent resistance, weather resistance, etc. of the coating film are lower than those of the example.

[Effects of the Invention] The thermosetting coating composition of the present invention forms a coating film having excellent properties such as scratch resistance, gloss, gasoline resistance, hot water resistance, and weather resistance. It is extremely useful as an automobile body paint.

Supplementary Note: A thermosetting coating composition in which the total amount of the acrylic copolymer (A) and the polyisocyanate compound FB) is 100 parts by weight, and the alkyl etherified melamine resin (C1) is contained in a range of 30 parts by weight or less.

Patent applicant: Mitsubishi Rayon Co., Ltd.

Claims (2)

[Claims] (1) (a) At least one hydroxyl group-containing (meth)acrylic ester represented by the following general formula (I) 10-
60% by weight, ▲Mathematical formulas, chemical formulas, tables, etc.▼(I) (In the formula, R^1 represents a hydrogen atom or a methyl group,
R^2 represents an organic substituent represented by the following general formula (II), (III) or (IV). ) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (II) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (III) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (IV) (In the formula, R^3, R^ 4, R^5, R^6 and R^7
represents a hydrogen atom or a methyl group, l represents an integer of 2 to 5, j represents an integer of 2 to 10, k represents an integer of 1 to 7, and m represents an integer of 1 to 3, respectively. ) (b) 0.1 to 10 vinyl monomers containing at least one carboxyl group, sulfonic acid group or phosphoric acid group
Weight% (c) 15-60% by weight of (meth)acrylic acid ester represented by general formula (V) ▲ Numerical formulas, chemical formulas, tables, etc. are available ▼ (V) (In the formula, R^8 is a hydrogen atom or a methyl group , R
^9 represents a hydrocarbon substituent having 4 or more carbon atoms. ), and (d) 0 to 50% by weight of at least one other copolymerizable vinyl monomer, with a hydroxyl value of 70 to 180 mgK.
In terms of OH/g, the acid value is 0.5 to 30 mgKOH/g, and the glass transition temperature is -50°C to 70°C. Acrylic copolymer (A) and (2) Equivalent amount of OH groups containing the polyisocyanate compound (B) and present in the acrylic copolymer (A)
X) and the equivalent of the NCO group in the polyisocyanate compound (
A thermosetting coating composition characterized in that the ratio X/Y of Y) is in the range of 1/0.5 to 1/1.5.