JPH0586320A - Coating resin composition - Google Patents

Abstract

PURPOSE:To prepare a compsn. which gives a coated stainless steel sheet hardly getting rusty even at high temps. and humidities by compounding a fluororesin having cross-linking sites with a polymer having structural units derived from a specific benzophenone or benzotriazole compd. CONSTITUTION:The objective compsn. is prepd. by compounding 100 pts.wt. fluororesin having cross-linking sites with 5-70 pts.wt. coating resin stabilizer which consists of 1-30mol% structural units derived from a benzophenone compd. of formula I (wherein R1 is H or alkyl; R2 is H or OH; R3 is H or methyl; and (n) is 0 or 1) or a benzotriazole compd. of formula II (wherein R is H or methyl), 70-99mol% structural units derived from a compd. of formula III, 0-20mol% structural units having hydroxyl groups, and 0-5mol% structural units having carboxyl groups and has a number-average mol.wt. of 2,000-20,000.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a resin composition for paint.

[0002]

2. Description of the Related Art A method of adding a UV absorber (hereinafter sometimes abbreviated as UVA) to a curable resin composition to improve its own weather resistance or to impart UV shielding properties. Is common practice. However, in the method of simply adding UVA, since UVA is volatilized at the time of forming a coating film by baking, a thin film or the like has a poor effect of improving weather resistance or ultraviolet shielding property, and when a large amount of UVA is added, The phenomenon of bleeding out becomes remarkable, and there are problems that the ultraviolet shielding property is deteriorated with time, the appearance is deteriorated, and the surface is easily soiled. Further, in the case where a coating resin composition containing a fluororesin copolymer having a cross-linking site is directly clear-coated on a stainless plate to be used for applications such as precoat metal, the adhesion of the coating film due to volatilization of UVA There is a problem that rust is generated at the interface between the coating film and the stainless steel plate due to the decrease.

As a method for solving these problems, a method of using as a UVA a polymer of a benzophenone compound or a benzotriazole compound having a reactive double bond that is hard to volatilize during heat treatment of a curable composition JP-A-62-81376 and JP-A-63-1399.
58 have been proposed. Further, Japanese Patent Laid-Open No. 1-287160 proposes a method in which reactive UVA is reacted with the curing reactive site of the fluororesin copolymer to immobilize it. However, the above-mentioned polymers of benzophenone-based or benzotriazole-based compounds have poor solubility in a solvent and compatibility with a fluororesin copolymer. Further, in the method of immobilizing the fluororesin copolymer by reacting it with reactive UVA, the solubility in a solvent is extremely lowered.

[0004]

Since conventional stabilizers for paints have the above-mentioned drawbacks, when they are mixed with a fluororesin copolymer to form a resin composition for paints, phase separation and solid content There were problems such as sedimentation.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has a good compatibility with a fluororesin copolymer and a stabilizer for a coating composition which is excellent in solubility in a solvent. It is intended to provide a resin composition for coating which comprises the resin stabilizer for coating and a fluororesin copolymer.

The stabilizer for paints of the present invention is a benzophenone compound represented by the general formula (A) or a general formula (B) in order to obtain compatibility with the fluororesin copolymer and sufficient solubility in a solvent. 1 to 30 mol% of the polymerized units (1) based on the benzotriazole-based compound represented by the formula (1) and 70 units of the polymerized units (2) based on the compound represented by the general formula (C).
~ 99 mol%, 0 to 2 polymer units (3) having a hydroxyl group
0 mol% and 0 of the polymerized unit (4) having a carboxyl group
Contained at a ratio of 5 mol% and a number average molecular weight of 2000 to 2
It is an essential condition that it is 0000.

[0007]

[Chemical 4]

[0008]

[Chemical 5]

[0009]

[Chemical 6]

In the present invention, the benzophenone compound having a reactive double bond is represented by the general formula (A). In the general formula (A), the alkyl group represented by R ₁ is methyl, ethyl, propyl, isopropyl, butyl, hexyl, heptyl, octyl, nonyl, decyl,
Undecyl and the like.

Therefore, as the benzophenone compound represented by the general formula (A), 2-hydroxy-4- (2-
Methacryloyloxyethoxy) benzophenone, 2-
Hydroxy-4- (2-acryloyloxyethoxy)
Benzophenone, 2-hydroxy-4- (2-methacryloyloxybutoxy) benzophenone, 2-hydroxy-4- (3-methacryloyloxy-2-hydroxypropoxy) benzophenone, 2-hydroxy-4-
(3-acryloyloxy-2-hydroxypropoxy) benzophenone and the like can be mentioned.

The benzotriazole compound having a reactive double bond is represented by the general formula (B).

Further, the compound represented by the general formula (C) is used as an essential polymerization unit for facilitating the dissolution of the resin stabilizer for coating composition of the present invention in a solvent and for making it compatible with the fluororesin copolymer. Based polymerized units.

Therefore, the compounds represented by the general formula (C) include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, and (meth) acrylic acid. Butyl, isobutyl (meth) acrylate, butyl (meth) acrylate, tert-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, cyclohexyl (meth) acrylate, etc. Is mentioned. These monomers may be used either individually or in combination of two or more. The term “(meth) acrylic acid” means methacrylic acid or acrylic acid. Same as below.

Further, as the monomer having a hydroxyl group,
Number of carbon atoms such as 2-hydroxyethyl (meth) acrylate and hydroxypropyl (meth) acrylate is 1 to
There are 24 hydroxyalkyl esters.

Examples of the monomer having a carboxyl group include α, β-ethylenically unsaturated carboxylic acid such as acrylic acid, methacrylic acid, itaconic acid and crotonic acid.

In the present invention, the fluororesin copolymer having a crosslinking site contains fluoroolefin, an unsaturated monomer copolymerizable therewith, and an unsaturated monomer having a crosslinking site as a copolymerization component. , In tetrahydrofuran 3
Those having a molecular weight such that the intrinsic viscosity at 0 ° C. is in the range of about 0.01 to 4.0 dl / g are preferable.

Examples of the fluoroolefin include tetrafluoroethylene, chlorotrifluoroethylene, trifluoroethylene, vinylidene fluoride, hexafluoropropylene, pentafluoropropylene, and other fluoroolefins having about 2 to 4 carbon atoms. As the copolymerizable unsaturated monomer, vinyl ethers, vinyl esters, allyl ethers, allyl esters,
Examples thereof include olefins, haloolefins, acryloyl compounds, methacryloyl compounds, unsaturated carboxylic acids and their esters.

Further, the copolymerizable unsaturated monomer is copolymerized with one kind or two or more kinds. Examples of the unsaturated monomer include unsaturated monomers having a reactive group such as hydroxyalkyl vinyl ether, hydroxyalkyl allyl ether, glycidyl vinyl ether, glycidyl allyl ether, and hydrolyzable silyl group-containing vinyl compound.

In the present invention, as the curing agent, one having a group capable of reacting with the curing reaction site of the resin stabilizer for coating material and the curing reaction site of the fluororesin copolymer, and giving a good cured product, is used. Adopted. Examples of such a curing agent include polyisocyanates, aminoplasts, polybasic acid anhydrides and metal alkoxides.

Examples of the polyisocyanate system include polyisocyanate compounds such as hexamethylene diisocyanate, silyl isocyanate compounds such as methylsilyltriisocyanate, partial condensates and multimers thereof,
Examples include blocked polyisocyanate compounds in which the isocyanate group is blocked with a blocking agent such as phenol. Particularly, a non-yellowing type is preferably used.

As the aminoplast, melamine resin,
Guanamine resin, urea resin, etc. are adopted. Among them, melamine at least partially etherified with one or more lower alcohols such as methanol, ethanol, propanol and butanol is used.

As the polybasic acid anhydride, phthalic anhydride,
Examples thereof include aromatic polyvalent carboxylic acid anhydrides such as pyromellitic dianhydride, and aliphatic polyvalent carboxylic acids such as maleic anhydride and succinic anhydride.

In the present invention, the blending amount of each component can be appropriately selected, but in order not to impair the excellent coating performance of the fluororesin copolymer such as weather resistance, the above-mentioned fluororesin copolymer An amount of about 5 to 70 parts by weight of the resin stabilizer for coating material and about 0.5 to 300 parts by weight of the curing agent is used per 100 parts of the combined material.

The composition of the present invention may optionally contain various additives in addition to the above three components. Such additives include solvents, synthetic resins, curing catalysts, heat stabilizers,
Examples include leveling agents, lubricants, pigments, dyes, viscosity modifiers, dispersion stabilizers, gelation inhibitors, and the like. It is desirable that the above three components are dispersed or dissolved in a suitable solvent.

Examples of the solvent include aromatic hydrocarbons such as xylene and toluene, alcohols such as n-butanol, esters such as butyl acetate, ketones such as methyl isobutyl ketone, and ethyl cellosolve glycol ethers. In addition, various commercially available thinners can be adopted, and these can be mixed and used at various ratios. As the synthetic resin, acrylic resin,
A phenol resin, an epoxy resin, a polyimide resin, a polyamide resin, a polyether resin, a silicone resin, or an elastomeric material such as polyurethane or an acrylic elastomer is used. Moreover, these precursors may be blended. Preferably, it has a group similar to or capable of reacting with the reactive site of the fluororesin copolymer and the resin stabilizer for paints.

When the curable resin composition of the present invention is prepared, use is made of various compounding machines such as a ball mill, a sand mill, a jet mill, a kneader, a triple roll, a paint shaker and the like which are usually used for preparing a resin composition. You can

[0028]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples.

[Synthesis Example 1] (Synthesis of Resin Stabilizer for Paint (P-UVA1)) Azobisisobutyronitrile (0.1 g) and ethyl acetate (50 g) were placed in a 500 L three-necked flask and heated to 80 ° C. for 2 hours. -Hydroxy-4- (3-methacryloyloxy-2-hydroxypropoxybenzophenone was added to 10.9
g, n-butyl methacrylate 39.1 g, dodecyl mercaptan 1.5 g, azobisisobutyronitrile 0.
A solution consisting of 1 g and 150 g of ethyl acetate was added dropwise over 3 hours. Then, the mixture was stirred at the same temperature for 2 hours to give a resin solid content of 49
%, A solution of a resin stabilizer for paint having a number average molecular weight of 6700 by gel permeation chromatography was prepared.

[Synthesis Example 2] (Synthesis of Resin Stabilizer for Paint (P-UVA) 2) 0.1 g of azobisisobutyronitrile and 50 g of ethyl acetate were placed in a 500 L three-necked flask and heated to 80 ° C. 2- (2'-hydroxy-3'-methacryloylamino-5-tertiaryoctyl) benzotriazole was added to 10.
3 g, n-butyl methacrylate 12.0 g, 2-ethylhexyl methacrylate 2.7 g, methacrylic acid 0.6 g, dodecyl mercaptan 0.5 g, azobisisobutyronitrile 0.1 g, ethyl acetate 20 g Was added dropwise over 3 hours. Then, the mixture was stirred at the same temperature for 2 hours to prepare a resin stabilizer solution having a resin solid content of 49% and a number average molecular weight of 11,300.

Examples 1 to 10 and Comparative Examples 1 and 2 Fluororesin copolymers A-1 to A-4 shown in Table 1, resin stabilizers P-UVA1-2 for paints obtained in the above-mentioned synthesis examples, and ultraviolet absorption. The agents BP-1 to 2, the curing agent, the catalyst and the solvent were uniformly mixed in the proportions (parts by weight) shown in Table 2 to obtain a resin composition for coating. This composition was applied onto a stainless steel plate using a film applicator so as to have a dry film thickness of 25 μm, and then dried and cured to obtain a test piece. For each test piece, Table 3 shows the results of visually confirming the rusting state of the stainless steel plate and the state of the coating film surface after irradiation with the germicidal lamp.

Here, the ultraviolet absorber is BP-1: 2-
Hydroxy-4-methoxybenzophenone, BP-2:
Indicates 2- (2-hydroxy-3-aminomethyl) benzotriazole.

The coating film drying conditions are those of Examples 1, 2, 6, 8 and
And Comparative Examples 1 and 2 are 220 ° C. × 1 minute, and Examples 3 and 4 are
5 and 7 are 220 ° C. × 10 minutes.

[0034]

[Table 1]

In Table 1, TFE is tetrafluorolene, C
TFE is chlorotrifluoroethylene, CHVE is cyclohexyl vinyl ether, EVE is ethyl vinyl ether, HBVE is hydroxybutyl vinyl ether, GV
E represents glycidyl vinyl ether.

[0036]

[Table 2]

[0037]

[Table 3]

[0038]

EFFECTS OF THE INVENTION The resin composition for coating composition of the present invention retains its ultraviolet absorbing property even under severe conditions such as high temperature and high humidity where rust is likely to occur. In applications such as painting where rust is likely to occur, the life of the substrate can be dramatically improved.

Claims (3)

[Claims] 1. A fluororesin copolymer 100 having a crosslinking site.
1 to 30 mol% of the polymerized unit (1) based on either the benzophenone compound represented by the following general formula (A) or the benzotriazole compound represented by the general formula (B) per part by weight, 70 to 99 mol% of polymerized units (2) based on the compound represented by formula (C), 0 to 20 mol% of polymerized units (3) having a hydroxyl group, and 0 to 0 polymerized units (4) having a carboxyl group. A resin composition for coating composition containing 5 to 70 parts by weight of a resin stabilizer for coating composition having a number average molecular weight of 2000 to 20000 in an amount of 5 mol%. [Chemical 1] [Chemical 2] [Chemical 3] 2. A fluororesin copolymer having a crosslinking site,
The paint according to claim 1, which is a fluororesin copolymer soluble in a solvent containing fluoroolefin and vinyl ether as copolymerization components and having an intrinsic viscosity of 0.05 to 2 dl / g measured in tetrahydrofuran at 30 ° C. Resin composition. 3. A precoated metal having a cured coating film of the coating resin composition according to claim 1 on a stainless steel plate.