JPS62164738A - Paint composition for polyurethane resin molding - Google Patents

Abstract

PURPOSE:To obtain the titled composition which well serves as both a primer and a top-coating, by mixing a specified thermosetting paint composition with pyrrolidone (derivative) and an epoxy-group-containing compound. CONSTITUTION:A thermosetting paint composition is obtained by mixing a polyester polyol resin (A), obtained by reacting a polybasic acid component with a polyol component, with a crosslinking agent (B) comprising an aminoaldehyde resin (a) or a polyisocyanate compound (b). 100pts.wt. mixture of 50-95pts.wt. this composition and 5-50pts.wt. epoxy group-containing compound (C) of a number-average MW of 100-10,000 is mixed with 5-200pts.wt. pyrrolidone (derivative) (D) and the resulting mixture is mixed with, optionally, a solvent, a pigment, a plasticizer, a film-strengthening resin, a film modifier, etc., to obtain the titled composition. This composition is applied to the surface of a polyurethane molding and crosslinked by curing at 70-180 deg.C for 1-100min where the crosslinking agent is component (a) or at room temperature -180 deg.C for 1min-24hr where the crosslinking agent is component (b).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coating composition for polyurethane resin molded articles having good primer function and topcoat function.

Polyurethane resin has excellent flexibility and lightness.

Due to its moldability, the molded products can be used in automobiles, ships, airplanes, etc.
Widely used for furniture, etc. However, the weather resistance of polyurethane resins used for molded products is extremely poor due to their chemical structure, and they are usually coated for purposes such as protection and to increase the added value of molded products.

Conventionally, the coating system has generally been to apply a primer specifically designed for polyurethane resin, and then apply an ordinary flexible topcoat. As a dedicated primer, MDI
Products using (4,4°-diphenylmethane diisocyanate)-based polyurethane resin are known, and their functions are to provide strong adhesion to polyurethane resin molded products, flexibility that follows the material, and scattering on the surface of the material. This is the ability to cover pinholes. Furthermore, as flexible top coats, one-component curing paints such as acrylic melamine resin, polyester melamine resin, and alkyd melamine resin, and two-component curing paints such as acrylic isocyanate resin and polyester isocyanate resin are known. Its functions include finishing properties such as gloss and sharpness, durability against heat, light, rain, and chemicals, and flexibility that follows the material.

However, such conventional painting methods require at least two steps: applying and drying the brimer, then applying and baking a topcoat. Also, due to the design of the molded product, if a two-tone finish is used and some parts are left unpainted,
There was a problem in that the weather resistance of the unpainted area deteriorated significantly and chalking occurred in about one year, which was not aesthetically pleasing.

The present inventors conducted intensive studies to solve the above-mentioned problems, and as a result, added an epoxy group-containing compound and pyrrolidone or a derivative thereof to a flexible top coat consisting of a polyester resin and a crosslinking agent (melamine resin or polyisocyanate). The present invention was completed based on the discovery that a coating composition made of the following has both good primer and topcoat functions.

Therefore, according to the present invention, (C) pyrrolidone or a derivative thereof and (D) a number average molecular weight 100-1
A coating composition for a polyurethane resin molded article is provided, which is characterized in that it contains 0,000 epoxy group-containing compound.

By applying the coating composition of the present invention to a polyurethane resin molded article, it can provide both primer and topcoat functions in one step, providing a coated article with functions equivalent to or superior to conventional two-step coated articles. It is something to do.

The coating composition of the present invention will be explained in detail below.

The polyester polyol resin used as component (A) includes phthalic acid and its acid anhydride, isophthalic acid, terephthalic acid, trimellitic acid and its acid anhydride, hexahydrophthalic acid and its acid anhydride, succinic acid, adipic acid, Polybasic acid components such as pimelic acid, sebacic acid, and brassylic acid, ethylene glycol, diethylene glycol, propylene glycol, neopentyl glycol, 1,6-hexanediol, trimethylolpropane, glycerin, pentaerythritol, tricyclodecane dimetatool It can be produced by condensation polymerization of polyol components such as, etc. according to a conventional method. In this case, for example benzoic acid, p-t
- The molecular weight may be adjusted by using butyl benzoic acid, etc. Also, fatty acids such as coconut oil fatty acids, tall oil fatty acids, castor oil fatty acids, etc. It may be used and oil-denatured.

Further, it may be modified by chain extension with 1,6-hexamethylene diisocyanate or the like.

These polyester polyol resins must have a hydroxyl value necessary for crosslinking and preferably have appropriate flexibility.

The crosslinking agent of component (B) is for crosslinking and curing the polyester polyol resin of component (A), and is usually an amine aldehyde resin or a polyisocyanate compound.

Aminoaldehyde resin contains melamine and melamine as amine components.
It is produced by the reaction of fluorine, benzoguanamine, acetoguanamine, steroguanamine, spiroguanamine, dicyandiamide, etc., and aldehyde. Examples of the aldehyde to be reacted with the amine component include formaldehyde, paraformaldehyde, acetaldehyde, and benzaldehyde. Note that the aminoaldehyde resin is denatured with a suitable alcohol, and examples of alcohols used for denaturation include methyl alcohol, ethyl alcohol, n-propyl alcohol, i-propyl alcohol,
n-butyl alcohol, i-butyl alcohol, 2-ditylbutanol, 2-ethylhexanol, benzyl alcohol, lauryl alcohol, ethylene glycol monomethyl ether (methyl cellosolve), ethylene glycol ethyl ether (ethyl cellosolve), engineered ethylene glycol monobutyl ether (butyl cellosolve),
Diethylene glycol monoethyl ether (methyl calpitol), diethylene glycol monoethyl ether (ethyl carpitol) When using hexamethoxymethyl melamine or a melamine resin in which a portion of its methoxy group is substituted with an alcohol of 04 or higher, for example, para-toluenesulfonic acid. It is preferred to add a conventional curing catalyst such as.

The polyisocyanate compound may be a commercially available one, and includes biuret type, incyanurate type, polyhydric alcohol addition type, and the like. The incyanate monomer used as a raw material for these is selected from those with good weather resistance. For example, hexamethylene diisocyanate, inphorone diisocyanate, etc. are good. When using these curing agents, it is necessary to mix them with the base paint (polyester polyol resin). Mix the curing agent (polyisocyanate compound) immediately before use 2
Although it is a liquid type, the above-mentioned polyisocyanate compound can also be used as a block type incyanate compound to form a l-liquid type paint by using a suitable blocking agent.

Pyrrolidone or its derivative as component (C) is used for the purpose of swelling the surface of the polyurethane resin molded product, and is used in an amount of 5 to 200 PHR (parts by weight/100 weight of the resin of components (A), (B), and CD). part) preferably 1O-1
It is good to add 00PHR.

Pyrrolidone or its derivatives are liquid at room temperature and have a strong ability to dissolve many organic compounds, so they are generally widely used as industrial solvents. Specifically, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-vinyl-2-
Examples include pyrrolidone.

These pyrrolidones or their derivatives are so-called "strong solvents" and have a strong cohesive force, such as polyurethane resin moldings, and can even swell thermosetting resins. However, because of its high boiling point, water absorption, and high price, it is not normally used as a paint solvent.

If the amount of component (C) added is 200 PHR or more, due to its high boiling point, it may remain in the coating film even after baking, resulting in moisture absorption, the coating film becoming sticky, and a decrease in moisture resistance. In addition, if it is less than 5 PHR, the swelling effect of the polyurethane resin molded product will be small and the adhesion will decrease, so it is not suitable.

The epoxy group-containing compound of component (D) has a strong affinity between polar groups with the polyurethane resin due to its polarity based on its glycidyl group and hydroxyl group, and exhibits strong adhesion to the polyurethane resin molded product. Ingredients used (
The epoxy group-containing compound D) has an epoxy group (-CHC
H2) in one molecule.

As such epoxy group-containing compounds, compounds known per se can be used, and include, for example, polyglycidyl ethers of polyphenols that can be produced by reacting polyphenols with epichlorohydrin in the presence of an alkali. Examples of polyphenols that can be used here include bis(4-hydroxyphenyl)-2,2-propane, 4,4°-dihydroxybenzophenone, bis(4-hydroxyphenyl)-1
,1-ethane,bis-(4-hydroxyphenyl)-1
, 1-isobutane, bis(4-hydroxy-tert-
Examples include butyl-phenyl)-2°2-propane, bis(2-hydroxynaphthyl)methane, and 1,5-dihydroxynaphthalene. Furthermore, an epoxy group-containing compound obtained by reacting diglycidyl ether with the above polyphenol and further reacting this with epichlorohydrin can also be used.

Hydrogenated compounds in which hydrogen is added to some or all of the double bonds of the aromatic polyphenols can also be used, and hydrogenated compounds are preferred from the viewpoint of weather resistance.

Other epoxy group-containing compounds that can be used include polyglycidyl ethers of phenolic novolac resins and polyglycidyl ethers of polyhydric alcohols. Examples of polyhydric alcohols include ethylene glycol, diethylene glycol, triethylene glycol,
1.2-Flopylene Glycol, 1,4-7' Robylene Glycol, 1,5-bentanediol, 1,2゜6
-hexandriol, glycerol, bis(4-hydroxycyclohexyl)-2,2-7'lopane, sorbitol, and the like.

In addition to the above, monohydric alcohols such as phenol, 2-
Ethylhexyl alcohol can also be used.

In addition, polycarboxylic acids such as succinic acid, geltaric acid, terephthalic acid, 2,6-naphthalene dicarboxylic acid,
Polyglycidyl esters such as bilayered lyric acid can also be used.

An epoxy group-containing monomer, such as glycidyl acrylate or glycidyl methacrylate, by itself or in combination with one or more other polymerizable ethylenically unsaturated monomers, such as methyl acrylate, ethyl acrylate, methyl methacrylate, acrylamide. Epoxy group-containing acrylic polymers obtained by polymerizing with , methacrylamide, acrylonitrile, methacyclonitrile, styrene, etc. can also be used.

Furthermore, epoxidized polybutadiene, epoxidized polycycloalkene, etc. can also be used.

The above-mentioned epoxy group-containing compound has a number average molecular weight of 100
N10,000, preferably 200 to 5,000, is suitable, especially those with an epoxy equivalent of 2.000 or less,
Preferably, polyglycidyl ethers of polyphenols and hydrogenated products thereof and polyglycidyl ethers of polyhydric alcohols having a molecular weight of 87 to 1.000 are suitable. Commercially available products include, for example, polyphenol polyglycidyl ether type Epiko.
te 828 (manufactured by Shell Chemical Co., Ltd.) Average molecular weight approximately 380
, epoxy equivalent: approx. 190 Hydrogenated polyphenol polyglycidyl ether type Santo) ST-5080 (manufactured by Tobu Kasei Co., Ltd.) Average molecular weight: approx. 1.200° Epoxy equivalent: 600 Polyhydric alcohol polyglycidyl ether type Denacol EX314 (Nagaushi Sangyo Co., Ltd.) (manufactured by Co., Ltd.) with an average molecular weight of 260 and an epoxy equivalent of 145.

If the number average molecular weight of the epoxy group-containing compound is greater than 10.000, the compatibility with the polyester polyol of the base resin will be poor, and the diffusion rate to the material surface will be low, resulting in a decrease in adhesion. If the number average molecular weight is less than 100, it generally evaporates easily and is difficult to remain in the coating film components, and even if it remains, it causes problems such as stickiness. Further, if the epoxy equivalent is 2.000 or more, the concentration of epoxy groups in the molecule is low, resulting in a decrease in adhesion to the material.

The amount of the epoxy group-containing compound (D) is 5 to 50 parts by weight based on the total of 50 to 95 parts by weight of components (A) and (B).
Parts by weight, preferably in the range of 10 to 30 parts by weight, such that the total amount is 100 parts by weight. If the amount is less than 5 parts by weight, the adhesion will be poor, and if it is more than 50 parts by weight, the strength of the coating will decrease, and the durability, weatherability, physical properties, etc. will decrease.

The solvent used in the coating composition of the present invention is a solvent commonly used in coatings. However, when using a polyisocyanate compound as a crosslinking agent, among the following alcohol solvents cannot be used.

Examples of solvents include aromatic solvents such as toluene and xylene, ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone, ester solvents such as n-butyl acetate and ethyl acetate, and alcohol solvents such as methanol and n-butanol. , cellosolve-based solvents such as ethyl cellosolve, butyl cellosolve, ethylene glycol monoethyl ether acetate (cellosolve acetate), carpitol-based solvents such as ethyl carpitol, butylcarbyl, diethylene glycol monoethyl ether acetate (carpitol J reacetate), heptane , saturated hydrocarbon solvents such as octane and cyclohexane, and one or more of ether solvents, petroleum solvents, mineral spirits, and the like.

The coating composition of the present invention can be made into a coating by blending pigments using a conventional pigment dispersion method. Examples of pigments that can be used include inorganic pigments such as metal oxides and hydroxides, chromates, silicates, sulfides, sulfates, and carbonates, various organic pigments, carbon black, and various metals. Pigments used in regular paints, such as flakes, are used. Of course, even transparent coating compositions containing no pigment can be used.

The coating composition of the present invention may contain, as desired, a plasticizer or plastic resin, a resin for strengthening the coating film, a dispersant, a coating surface conditioner, a fluidity conditioner, an ultraviolet absorber, an ultraviolet stabilizer, an antioxidant, and a crosslinking agent. Various known additives such as reaction accelerators and crosslinking reaction inhibitors can be added and used.

The method for producing the coating composition of the present invention using the above-mentioned components may be performed using the same equipment and steps as in conventional coating production methods. For example, use a suitable dispersion machine such as a ball mill, sand mill, or roll mill to create a pigment paste by dispersing the pigment in a mixture of binder and solvent, then add the necessary ingredients and mix uniformly with a disperser, etc. It can be made into a paint using a method.

The coating composition of the present invention can be applied by conventional coating methods. In other words, a paint diluted with a solvent to a suitable viscosity for painting can be applied at room temperature or at elevated temperatures using an air spray machine, an airless spray machine, various electrostatic atomizers, dipping, a roll atomizer, a brush, etc. .

After coating, the coating composition of the present invention is crosslinked and cured by heating or at room temperature. For example, when using aminoaldehyde resin as a crosslinking agent, the heating conditions are 70 to 180°C and 1 to 1
If a polyisocyanate compound is used as a crosslinking agent, select an appropriate temperature and time condition within the range of 00 minutes, or for 1 hour at room temperature to 180°C for 1 minute to 24 hours. All you have to do is choose.

The coating composition of the present invention may be applied onto a polyurethane molded article and used as is, or it may be further coated with a top coat to achieve a two-tone color finish.

The coating film made from the composition of the present invention obtained in this manner exhibits strong adhesion to polyurethane resin molded articles, and exhibits excellent adhesion not only in the initial adhesion test, but also in the moisture resistance test, gasoline immersion test, and weather resistance test. Maintain good adhesion. Furthermore, it fully satisfies the performances required as a top coat for polyurethane resin molded articles, such as gloss, image clarity, chemical resistance, physical properties, and weatherability.

The mechanism by which strong adhesion is obtained as described above is, firstly,
The lolidone solvent in the applied paint penetrates into the skin of the polyurethane resin molded product and moistens it with IFL. Polyester polyol resin, aminoaldehyde resin (or polyisocyanate compound) diffuses into the swollen material skin,
Penetrate. This process is accelerated by compounds containing epoxy groups. Epoxy groups are highly polar and have a high affinity with urethane structures, which also have high polarity, resulting in strong adhesion.

In this way, the polyester polyol resin and aminoaldehyde resin that penetrated into the skin of the polyurethane resin molded product,
When baked, it reacts and crosslinks and hardens.

That is, the coating composition of the present invention penetrates into the skin of the material, crosslinks and cures, and therefore integrates with the material and exhibits strong adhesion.

Further, since there are no particular restrictions on the polyester polyol resin and aminoaldehyde resin, ordinary ones conventionally used as top coats for polyurethane resin molded products can be used.

Hereinafter, the effects of the present invention will be explained using examples.

Note that parts and % indicate parts by weight and % by weight.

[Preparation of paint material] Reaction injection molding polyurethane resin (RIM-PU) used for automobile exteriors
Molded product or fiber reinforced product thereof (R-RIM PU)
were exposed to trichloroethane vapor for 1 minute to obtain degreased retest beads.

Example 1 Polyester polyol resin, aminoaldehyde resin,
A black pigment and a solvent were mixed in the following weight ratio and dispersed in a ball mill to obtain a black paste.

Part Xylene 20 Cellosolve Acetate 20 (Note 1) Manufactured by Mitsui Toatsu Chemical Co., Ltd., trade name Orestar Q3469 (Note 2) Manufactured by Mitsui Toatsu Chemical Co., Ltd., trade name Kneepan 2R (Note 3) Manufactured by Capot Co., Ltd., trade name Black Pearls 13
00 Epoxy compound in contrast to the above black paste.

2-pyrrolidone and the like were blended as shown below to obtain black enamel.

Buguro Paste 193 Epicote 82
8 (Note 4) 102-pyrrolidone
20223, Ol (Note 5) Manufactured by Shin-Etsu Chemical Co., Ltd. The thus obtained paint was heated to a viscosity of 18 seconds (Ford cup #4.20°C) with a mixed solvent of xylene/butyl acetate/methyl ethyl ketone = 50/30/20 (weight ratio). ). The diluted paint was air-sprayed onto the above-mentioned coating material to a dry film thickness of about 30 microns, and left to stand at room temperature for 10 minutes.

Electric hot air dryer! A coated plate was made by baking it in a machine at a temperature of 120°C for 30 minutes.

Furthermore, half of the obtained coated plate was masked, and a commercially available top coat for plastics (manufactured by Kansai Paint Co., Ltd., trade name: Shiflex No. 1200 White) was painted and baked in the same manner as above to create a test coated plate. . The test results of the obtained coated plates are shown in Table 2.

Example 2 An epoxy compound, N-methyl-2-pyrrolidone, etc. were blended in the following manner to a black paste prepared in the same manner as in Example 1 to obtain a black enamel.

Buguro Paste 171, 6 Santo 5T-508020 (Note 6) N-Methyl-2-pyrrolidone 90 Silicone Oil KP-3230, 01 281,61 Hereinafter, test coated plates were prepared by painting and baking in the same manner as in Example 1. Ta. The test results of the obtained coated plates are shown in Table 2.

Example 3 A polyester resin, a black pigment, and a solvent were mixed in the following weight ratio and dispersed in a ball mill to obtain a black paste.

Part xylene 20 Cellosolve acetate 20 (Note 7) Manufactured by Sumitomo Bayer AG, trade name Dismohen 670 To the above black paste, an epoxy compound, N-vinyl-2-pyrrolidone, etc. are blended as shown below to make black enamel. Obtained.

Black paste 103 Denacol EX
-314 (Note 8) 16N-vinyl-2-pyrrolidone
10 Silicone oil KP-3230,01 129,01 To 129.01 parts of the obtained black enamel, 24 parts of Schuraney 24A-100 (manufactured by Asahi Kasei Industries, Ltd.) was mixed as a polyisocyanate, and the same procedure as in Example 1 was carried out. I immediately baked the paint and made a test coated board. The test results of the obtained coated plates are shown in Table 2.

Comparative Example 1 The black enamel formulations of Examples 1 to 3 excluding the epoxy compound and pyrrolidone compound (Table 1
) was painted and baked in the same manner as in Example 1 to prepare a test coated board. The test results of the obtained coated plates are shown in Table 2.

Claims (1)

[Claims] 1. A thermosetting coating composition containing (A) a polyester polyol resin and (B) a crosslinking agent as main components, (C) pyrrolidone or a derivative thereof, and (D) a number average molecular weight of 100.
A coating composition for a polyurethane resin molded article, characterized in that it contains an epoxy group-containing compound of 10,000 to 10,000. 2. The coating composition for polyurethane resin molded articles according to claim 1, wherein the blending amount of component (C) is 5 to 200 PHR. 3. The blending amount of component (D) is 5 to 50 parts by weight based on 50 to 95 parts by weight of components (A) and (B) (total amount of 1
The coating composition for polyurethane resin molded articles according to claim 1, wherein the proportion is 0.00 parts by weight).