JPS6155169A - Paint composition - Google Patents

Abstract

PURPOSE:To provide a metallic paint compsn. for the high-solid base coat of two-coat one-bake automobile paint, which gives a coating film having an excellent appearance, consisting of a functional group-contg. polymer, an alicyclic polyepoxy resin, trifluoromethane sulfonic acid, aluminum flake and a pigment. CONSTITUTION:0.2-2.0wt% trifluoromethane sulfonic acid, 2-20wt% (based on the amount of resin on a solid basis) aluminum flake and 2-50wt% (based on the amount of resin on a solid basis) pigment are blended with 100pts.wt. of the combined amount of 90-30wt% polymer (A) contg. a functional group, such as acrylic resin contg. hydroxyl and/or carboxyl groups and having a number- average MW of 1,000-20,000, a glass transition temp. of -30-30 deg.C, a hydroxyl value of 40-120 and an acid value of 5-25 and 10-70wt% low-viscosity alicyclic polyepoxy resin (B) (e.g. vinylcyclohexene dioxide) which is liquid at room temp.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application: The present invention relates to a paint composition, and more particularly to a metallic paint composition for a high solids separation type pace coat of a two-coat, one-bake automotive paint. be.

Conventional technology and its problems: In recent years, even in the field of automobile paints, the solvent content is low, and wood/i
There has been a demand for a type of metallic paint composition that satisfies current air pollution regulations.

One way to solve these problems is to develop a metallic paint composition for automobiles in which fine crosslinked polymer particles called microgels are dispersed in a paint composition containing a resin vehicle (Japanese Patent Laid-Open No. 58-129066, Japanese Patent Laid-Open No. 58-1999). 5573) etc. have been proposed. Although these are useful for the workability of bainlid-based paints and for the orientation of aluminum, they pose problems in terms of dispersion stability and paint manufacturing since the microgels are dispersed in a resin vehicle after being manufactured.

On the other hand, a high solid content coating composition for top coatings for automobiles, etc., which does not use crosslinkable polymer fine particles (Japanese Patent Application Laid-open No. 1983-1989-1) has been developed.
145765) have been proposed, but although these are effective for painting with solid color paints, they have problems with the finished appearance due to problems with the orientation of aluminum when applied to metallic paints.

In view of the above-mentioned problems, the present inventors conducted intensive studies on a coating composition with a high solid content for a Meta IJ 7' paint layer without using crosslinkable polymer fine particles, and as a result, completed the present invention. Ta.

That is, the present invention comprises a polymer having a functional group (A), an alicyclic polyepoxy resin (B), trifluoromethanesulfonic acid (C), aluminum powder, and a pigment, and (A) and (B).
) and the weight ratio is 9[1:1o-30:7
0, and (the blending ratio of the sum of Shu and (B) and (B) is 100:0.2 to 100:2.0 as a weight ratio
This is a composition for automotive metallic paint, characterized in that the composition is within the range of .

In the present invention, the polymer (A) having a functional group includes:
Mention may be made of acrylic resins and polyesters m RW having hydroxyl groups and/or carboxyl groups. Here, the acrylic resin is made by blending monomers with a polymerization catalyst and optionally a chain transfer agent to obtain a 75 to 160"
It is generally produced by a solution polymerization method in which the polymer is continuously added dropwise into a solvent of C over a period of 2 to 6 hours to form a polymer.

In this case, examples of the monomer having a hydroxyl group include hydroxyethyl (methadiacrylate), hydroxypropyl (methadiacrylate), and hydroxybutyl (methadiacrylate).

Furthermore, examples of the monomer having a carboxyl group include acrylic acid, methacrylic acid, maleic acid, itaconic acid, and the like. Other monomers that can be copolymerized with these monomers include aromatic monomers such as styrene, vinyltoluene, and paramethylstyrene, methyl acrylate, ethyl ac-1-nolate, ethyl ac-1-nolate, and acrylic. Acrylic acid esters such as 2-ethylhexyl acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate,
Methacrylic acid esters such as 2-ethylhexyl methacrylate and stearyl methacrylate, alkyl fumaric acid esters, and alkyl itaconic acid esters can also be mentioned.

The acrylic resin referred to in the present invention usually has a number average molecular weight of 1.
000 to 20.000 (polystyrene equivalent molecular weight determined by gel permeation chromatography), glass transition temperature is in the range of -30 to 30 °C, hydroxyl group content is in the range of 40 to 120 as hydroxyl number, and carboxyl group content is in the range of acid Typical solvents used for producing the above acrylic polymers include toluene, ethyl acetate, methyl isobutyl ketone, methyl 9-amyl ketone, methyl isoamyl. Ketones, methyl ethyl ketone, ethylene glycol monoethyl ether acetate and other conventionally used aliphatic, cycloaliphatic and aromatic hydrocarbons, esters, ethers, ketones and alcohols.

About 0.1 to 6% by weight of polymerization initiator, based on the weight of monomer, is typically used to make acrylic polymers. Typical initiators include diazo compounds such as azobisisobutylnitrile, peroxides such as pe/silver oxide, tertiary-butyl bivalate, tertiary-butyl perbenzoate, and tertiary-butyl perkaplate.

Examples of chain transfer agents used in this case include 2-mercaptoethanol, dodecylmercaptan,
Examples include lauryl mercaptan.

Polyester which is the polymer (A) in the present invention/L=
14 fats usually have a number average molecular weight of SOO to 5,000 in terms of polystyrene, an acid value of 20 or less, and 20 to 2
Mention may be made of polymers with a hydroxyl number of 0.00.

These polyester resins are usually produced by charging each reaction component, optionally a suitable solvent, a reaction catalyst, etc. into one reaction vessel equipped with a cooler and a stirrer.

Examples of solvents useful in the above production include toluene, xylene, and other substituted benzenes. In addition, as a reaction catalyst, for example, diptyltin oxide,
Examples include organometallic compounds such as dibutyltin silaurylate and tetrabutoxy titanate, and organic acids such as sulfonic acid. The reaction can be carried out by heating in a temperature range of usually 100 to 250°C to carry out an esterification reaction while producing a polyester resin.

As each reaction component used in producing the polyester resin, commonly used polyhydric alcohols, polyhydric carboxylic acids, and polyhydric carboxylic acid alkyl esters can be used. Examples of polyhydric alcohols include ethylene glycol, propylene glycol, 1,4 butanediol, and
, 6 hexanediol, neopentyl glycol, dicyclohexane dimethylol, trimethylolpropane,
Examples include trimethylolethane, glycerin, pentol, and hydrogenated BPA.

As polyhydric carboxylic acids or their alkyl esters,
For example, glutaric acid, azelaic acid, adipic acid, sepatic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, cyclohexenedicarboxylic acid, these aliphatic dicarboxylic acids, aromatic dicarboxylic acids, alicyclic acids group dicarboxylic acids and their alkyl esters.

Alicyclic polyepoxy resin (B
) can include various compounds, but from the viewpoint of the effects in the present invention, alicyclic polyepoxy resins that are liquid at room temperature and have a relatively low viscosity are preferred from the viewpoint of a higher solid content. . Examples of this include vinylcyclohexene dioxide, dicyclopentadiene dioxide, and the like.

In the present invention, the blending ratio of the Tanuki-11 delirium polymer (8) and the alicyclic polyepoxy resin (B) is 90:10 to 5.
0:70 (weight ratio), more preferably 70:30
-40:60 range. Alicyclic epoxy resin (B)
When the blending ratio is less than 10 parts by weight, the hardenability of the coating film after baking is insufficient and it cannot be used as an automotive metallic paint composition. If the blending ratio of (B) is more than 70 parts by weight, the appearance of the metallic paint film will be poor and it cannot be used as a two-coat, one-base undercoat paint composition.

In addition, in the present invention, trifluorometalsulfonic acid Co for the polymer (A) and the alicyclic polyepoxy resin (B)
) The blending ratio is 100:0.2 to 100:2.
0 (weight ratio), more preferably 1oo:o.s
~100:1. It is 8. Therefore, the blending ratio of (B) is 0. When it is less than 2K, the curing property is not sufficient,
Maf, -2. When the amount is more than 0, the curability is sufficient, but the properties such as coating film discoloration and water resistance are slightly deteriorated, so that it cannot be used as a metallic coating composition.

Furthermore, in the present invention, a curing agent capable of reacting with hydroxyl groups and carpoquine groups may be mixed and used for purposes such as improving performance, within a range that does not impede the effects of the present invention. Examples of these include, for example, fully or partially alkylized using alcohols such as methanol, ethanol, butanol, melamine formaldehyde resins, aliphatic incyanates such as hexamethylene diisocyanate, isophorone diisocyanate, alicyclic Polyhydric alcohol adducts of incyanate O6 and their blocks can also be used.

In the present invention, trifluoromethanesulfonic acid is blended into the polymer (A"l and the alicyclic polyepoxy resin (B).
This coating composition is relatively stable at room temperature.If there is a problem with storage stability, trifluorometalsulfonic acid can be mixed with an amine compound, such as a tertiary amine such as bil-II ethylamine, or monoethanol. It is also possible to use an alkanolamine such as an amine by neutralizing or mixing it in advance with an equivalent or more than the same amount.

The coating composition of the present invention is similar to the ordinary automobile meth 1 knock coating composition, as well as meth 1 knock-on paint compositions such as aluminum powder, mica powder, etc.
1. Containing powders with gloss and pigments such as organic pigments and inorganic pigments, these aluminum powders usually have a weight ratio of 2 to 20% per solid resin content, and similarly pigments have a ratio of 2 to 50% by weight per resin solid content. Used within the weight category.

Furthermore, various commonly used additives, such as 6-j pigments, dispersants, leveling agents, antisettling agents, etc., may be used within the range that does not impede the effects of the present invention.

The composition for automotive metallic paint according to the present invention is used in applications that require an excellent coating film appearance for automotive exterior paints, and is effective in both 2-coat and 1-bake systems and other multilayer paint systems. It can be used for In particular, when used in a two-coat bake system, the use of a clear top coat can have a particularly remarkable effect on improving the appearance of the coated surface. In this case, it is preferable to use a thermosetting acrylic resin, especially since it is necessary to maintain the weather resistance of the Meta 117 coating film for a long time.

Application of such automotive metallic paint compositions can normally be carried out by means such as air spray painting, electrostatic air spray painting, etc., and the film thickness at that time is generally within the range of about 10 to 50 microns as a dry film. It is. After painting in this manner, a clear top coat is applied and baked according to the method currently practiced in automobile lines. The coating thickness at that time is also generally within the range of about 20 to 50 microns. Baking is usually done by using an electric hot air dryer, indirect hot air oven, direct hot air oven, far infrared oven, etc., to coat the coating film in a temperature range of about 80 to 180°C for about 10 to 45 minutes. This can be done by holding it.

The present invention will be further explained below with reference to Examples and Comparative Examples. In addition, parts and percentages in the examples indicate parts by weight.

Examples: Production example (1) (Production example of acrylic resin for top coat) A stirrer, thermometer, reflux cooling, etc. were added to a normal acrylic resin production equipment equipped with a dropping tank, etc. ) Product name, aromatic solvent) 67 parts were charged, heated and stirred, and after reaching 130''C, the following monomer mixture was added dropwise over 4 hours.

Styrene 20 parts 9-butyl methacrylate 40 2-ethylhexyl methacrylate 212-
Hydroxyethyl methacrylate 17 Methacrylic acid 2 α,α'-azobisisobutyronitrile 2
．． 5 After dropping the above monomer mixture, stirring was continued while keeping the temperature of the reaction vessel at 130°C for 1 hour, and then 10 parts of Tsurpetz+100, 0 parts of 2'-azobis-2,4-dimethylvaleronitrile, A mixture of 8 parts was added over 2 hours. Thereafter, the temperature was kept at 130° C. and the reaction was carried out for 2 hours, and then 3 parts of Tsurpetz #:100 and 15 parts of phosphorus-butanol were added to produce acrylic lateral force W(I). The solid content concentration of the solution was 50.0%, and the varnish viscosity (Gardner bubble viscosity 25° C.) was H.

Production Example (II) In the same manner as in Production Example (1), 10 parts of styrene, 25 parts of methyl methacrylate, 30 parts of ethyl acrylate, 21 parts of luptyl methacrylate, 12 parts of 2-hydroxyethyl ivy acrylate, and acrylic acid were added. Part 2, α-α
Polymerize in xylene using '-azobisisobutyronitrile, further dilute with xylene and n-butanol,
An acrylic resin solution (II) with a resin content of 50.0% and a varnish viscosity of O was obtained. The number average molecular weight of this resin is 10200
The hydroxyl value was 52 (solid content equivalent value) and the oxidation value was 11.8 (solid content equivalent value).

Production measurements) The following raw materials were charged into a 4-tube flask equipped with a stirrer, a temperature controller, and a reflux condenser, and heated while stirring.

Neopentyl glycol 221.0 parts Hexahydrophthalic acid 184.0 Inphthalic acid
132.8 Adipic acid 73.0 Heating was continued while removing water generated as the reaction progressed, and when the acid value reached 10, the reaction was terminated.

The obtained resin had an acid value of 9, a hydroxyl value of 95, and a number average molecular weight of 3,500. This resin was diluted with xylene to a solid content of 60 candy to obtain a polyester resin face.

Example 1 Materials having the following composition were weighed into a stainless steel container and stirred using a laboratory stirrer to prepare a coating composition.

Acrylic resin of production example (1) 40 parts 76
．． 0 [Note] × Aluminum content 53% This material was diluted with a solvent of Kijirol / ethylene glycol motsubutyl ether / ethyl acetate = 171' / 1,
A metallic paint composition was prepared by adjusting the viscosity to 20 seconds using a Ford cup llI4.

The non-volatile content of the composition of this example was 396%. Furthermore, a top coat paint was prepared using the top coat acrylic resin of Production Example (I) with the following formulation.

Production Example 1: Acrylic resin solution of I) 140 parts 60%
Butylated melamine cut finger 50 knee pants 203
E-60* 1 Silicone resin solution a, 1 (diluted with Kijiroll) [Note] *Mitsui Toatsu Chemical Co., Ltd. Part name The viscosity was adjusted at 20°C].The metallic paint composition was applied using an air spray gun onto a dull steel plate with a thickness of p and B mm, which had been treated with zinc phosphate, and left at room temperature for 5 minutes. After the top coat paint was applied using an air spray gun, it was left to stand for 10 minutes, and then heated and cured for 140°CCl2O minutes in an electric hot air dryer.The evaluation results of the resulting paint film are shown in Table 2.

Example 2.6 and Comparative Examples 1 to 3 A metallic paint composition with the composition shown in Table 1 was blended in the same manner as in Example 1, and then a top coat paint was applied. The evaluation results of the obtained coating film are shown in Table-2.

Claims (2)

[Claims] (1) Consists of a polymer (A) having a functional group, an alicyclic polyepoxy resin (B), trifluoromethanesulfonic acid (C), aluminum powder, and a pigment, and a combination of (A) and (B). The blending ratio is in the range of 90:10 to 30:70 by weight, and the blending ratio of the sum of (A) and (B) to (C) is 100:0.2 to 100:2.0 by weight. A composition for automotive metallic paint, characterized in that the composition is within the range of (2) The composition according to claim 1, wherein the polymer (A) having a functional group is an acrylic resin or a polyester resin having a hydroxyl group and/or a carboxyl group.