JPH023472A - Coating composition - Google Patents

Abstract

PURPOSE:To obtain a coating composition which gives a film with controlled yellowing and deterioration and improved in gloss, weatherability, and dustproofness by mixing a synthetic resin having OH groups in the molecule, a specified organosilicon compound and, if necessary, a melamine resin for crosslinking. CONSTITUTION:A straight-chain or branched fluorinated carboxylic acid and a chlorinated organic silane compound are allowed to undergo dehydrochlorination to give an organosilicon compound having perfluoroalkyl groups together with hydrolyzable groups and/or OH groups bound to an Si atom in the molecule (e.g., a compound of the formula). 100 pts.wt. synthetic resin having one or more OH groups in the molecule (e.g., an oil-free alkyd resin) is mixed with 40 pts.wt. or less said organosilicon compound and, if necessary, a melamine resin for crosslinking, and this mixture is dissolved in an organic solvent. If necessary, a pigment, an additive, etc., are incorporated into this solution.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a novel coating composition capable of forming a coating film that is rich in gloss and weather resistance and has dustproof properties.

(Prior Art) Conventional coating compositions and coating methods used for automobile exterior panels and the like are generally as follows. That is, a coating composition consisting of a general-purpose synthetic resin containing hydroxyl groups (e.g. alkyd resin), a melamine resin, pigments, fillers, additives, etc. is applied to the object to be coated by spray painting, etc., and then baked in an oven, etc. This is a method of drying it to form a coating film.

Furthermore, in recent years, the market demand for improving the quality of coatings for automobiles and the like has increased, and the weather resistance, stain resistance, oil resistance, etc. of coating films have become problems. As a solution to this problem, fluororesin paints have been disclosed (Japanese Patent Laid-Open No. 136662/1983, etc.).

These paints have excellent weather resistance and stain resistance because the C-FM combination in the resin molecules is stable and resistant to polarization. It is difficult to use for exteriors.Recently, paint compositions have been proposed that can increase gloss by introducing fluorine-containing groups into vinyl-based synthetic resins and form coatings with excellent weather resistance and oil resistance ( Japanese Patent Publication No. 60-147418.61-152
771.61-152773, etc.). That is, JP-A No. 60-147418 discloses that a perfluoroalkyl group-containing bicarbonate monomer and an organic silicone compound containing an alkenyl group and a hydrolyzable group bonded to a silicon atom and/or a hydroxyl group in the molecule. JP-A-61-152771 discloses a coating composition containing a copolymer obtained by copolymerizing an elementary compound and a vinyl monomer copolymerizable with both of them, in which a perfluoroalkyl group is polymerized. A resin composition for coatings containing a polymer obtained by introducing into a resin skeleton for coatings by reaction is disclosed.

(Problems to be Solved by the Invention) However, since all such coating compositions are polymerized by a radical polymerization reaction using a vinyl group-containing monomer, a relatively large number of unsaturated groups remain even after the coating film is formed. Therefore, there is a problem in that the coating film tends to yellow or deteriorate, and the characteristics of the fluorine group cannot be fully utilized.

(Means for Solving the Problems) The present invention has been made by focusing on such conventional problems, and includes a perfluoroalkyl group, a hydrolyzable group bonded to a silicon atom, and/or a perfluoroalkyl group in a molecule. Alternatively, the above-mentioned problems are solved by subjecting an organosilicon compound containing a hydroxyl group to a condensation reaction with a synthetic resin containing a hydroxyl group to obtain a coating film.

Therefore, the coating composition of the present invention comprises a synthetic resin (A) having one or more hydroxyl groups in the molecule and a perfluoroalkyl group and a hydrolyzable group bonded to a silicon atom and/or a hydroxyl group in the molecule. Containing organosilicon compound (B
), or a mixture in which a crosslinking melamine resin (C) is mixed into this mixture, and (A) component 1
It is characterized by containing component (B) in an amount of 40 parts by weight or less based on 00 parts by weight.

The present invention will be explained in detail below.

In the present invention, it is important to use an organosilicon compound containing a perfluoroalkyl group, a hydrolyzable group bonded to a silicon atom, and/or a hydroxyl group in the molecule as a component of the coating composition. It is desirable that the organosilicon compound has a perfluoroalkyl group, usually having 2 to 18 carbon atoms, preferably 2 to 8 carbon atoms. This is because, if the amount is too large, problems will arise in compatibility with other organic compounds. Furthermore, it is necessary that a hydroxyl group and/or a hydrolyzable group be bonded to the silicon atom. Examples of this hydrolyzable group include alkoxy groups such as methoxy, ethoxy, and propoxy groups;
Examples include an acyloxy group such as an acetoxy group and an octanoyloxy group, and an N-methylacetamide group.

Further, it is desirable that an organo group such as an ethylene chain or a carbonyl group be present between the perfluoroalkyl group and the silicon atom in order to improve compatibility with other organic compounds.

Examples of the organic compounds are shown below.

CF3CIL2COz (CH2) 4SI (OCH
*) 3(CF3) 2CI(CO2(CH2) 4S
I (OCH3) 3CF3CIbC02(C)12)
nsl(CO□CH3) *CF:I (CF2)C)
+2CO□C(CH3)(Cf12), 5i(C1ls
) 2 (mouth C2H3) CF3 (CF2) q (CH2
) 2CO□C(C)13) (CH2) 3c (C
113) CD2 (CH2) 3Sl(CH3) (
N(CH3)COCHz)2 These can be obtained by a dehydrochloric acid reaction between a linear or branched fluorinated carboxylic acid and a chlorinated chloro-containing organic silane compound. Such synthetic methods are known, and examples include the following.

CF+C6H4C[12H+ CIl-CJsSi(O
CH+) 3→CF:3C6H4CO□CJ6Si (
OCH3) 3 Next, the coating composition of the present invention is a mixture of components (A), (B) and (C), or (A)
It can be produced by dissolving a mixture of the components and component (B) in an organic solvent, and blending and kneading pigments, additives, etc. In this case, the amount of component (B) is selected to be (A>400 ls or less per 100 parts by weight of component.) If the amount of the fluorine group-containing organosilicon compound is too large,
It is not preferable because the compatibility with other compounds decreases, the surface hardness of the coating film is impaired, and the weather resistance deteriorates.

Moreover, in the coating composition of the present invention, a good coating film can be obtained by the following two methods.

The first method is to apply the coating composition obtained as described above to the object to be coated by spraying or brushing, and then baking or drying at room temperature to obtain a coating film having the desired physical properties. .

The second method involves dissolving components (A) and (B) in an organic solvent, blending and kneading pigments, additives, etc., and applying this composition to the object to be coated by spraying, brushing, etc. Thereafter, component (B) dissolved in a suitable solvent is applied and baked or dried at room temperature to obtain a coating film.

The coating film obtained using the coating composition of the present invention has relatively excellent gloss, and also has good weather resistance, stain resistance, water repellency, oil repellency, etc. Objects to be coated include automobiles, exteriors of buildings, ships,
A wide range of applications are possible, including home appliances and aircraft.

(Operation) Next, the operation will be explained. In the coating composition of the present invention,
Among the components, the perfluoroalkyl groups in the fluorine-containing organosilicon compound have low surface energy and therefore selectively migrate to the surface of the coating film, resulting in an increase in the orientation density of the perfluoroalkyl groups on the surface. Stain resistance of paint film,
This is why 1 water and 1 oil properties are good.

Furthermore, the glossiness can be sufficiently improved by the presence of a large amount of synthetic resin. Further, the compounds constituting the main ingredient can be easily crosslinked by dehydration condensation reaction between hydroxyl groups, and a coating film with sufficient mechanical strength can be obtained.

(Example) The present invention will be explained below with reference to Examples and Comparative Examples.
It goes without saying that the present invention is not limited in any way by this explanation.

Examples 1 to 4 and Comparative Example 1.4 Table 1 shows the blending ratios (parts by weight) of the coating compositions. The synthetic resin used in these Examples and Comparative Examples is an oil-free alkyd resin "VelaFlite M-6003-60J (Dainippon Ink & Chemicals Co., Ltd. ◇Kagami: trade name)," and the crosslinking melamine resin is "Superbe Socamin L117-60J."
(manufactured by Dainippon Ink & Chemicals Q@: trade name), and the perfluoroalkyl group-containing silicon compounds are the following three types ((
a), (b), and (C)) were synthesized and used. The pigment is titanium white "Taipe 7CR50" (trade name, manufactured by Ishihara Sangyo Co., Ltd.).

(a) CFsCH2COz (CL) ssl (OC
H3) 3-SL (NCOCH3) 2 l CH3CH3 As a test plate, a cold-rolled steel plate treated with zinc phosphate was used.
Electrodeposition paint "Power Top U-600J (Nippon Paint 01
Manufacturer: Product name) and intermediate coating paint “No\Yepico No, l c
P Sealer" (Nippon Oil & Fats side part: product name) was applied and baked and dried.

Each of the coating compositions shown in Table 1 was spray applied to the above test plate to a film thickness of 20 μm, and the coating compositions were heated at 140°C for 20 minutes.
Bake dry for ~30 minutes. Table 2 shows the surface properties of the resulting coating film. Incidentally, the surface characteristics were measured by the following method.

Initial gloss: 60 degree specular gloss test (JIS K 54
According to 006.7).

Stain resistance: Gloss retention rate (%) after washing with water after 4 months of outdoor exposure. ◎...90% or more, Δ...80% or more,
X...70% or less Weather resistance: Gloss retention rate (%) after 4000 hours on a Sunshine Weather-Oh meter. ◎・・・
90% or more, Δ...80% or more, ×...70% or less Water repellency: Water contact angle (°) at initial stage and after washing with water after 4 months of outdoor exposure Example 5 Paint with the formulation of Comparative Example 1 The composition was applied as described above, and the undried test plate was immersed in a 3% by weight Freon TF solution of the perfluoroalkyl group-containing silicon compound (C).
After lifting vertically at a speed of about 100°/second, it was heated to 140°C for 10
Baking drying was performed for a minute. The surface characteristics of the obtained coating film were
Shown in the table.

Comparative Example 2 A coating resin composition of Example 4 described in JP-A-61-152771 was prepared and subjected to the same test as Example 1. The surface properties of the coating film are shown in Table 2.

Comparative Example 3 The coating resin composition of Example 2 described in JP-A-60-147418 was prepared and subjected to the same test as Example 1. The surface properties of the coating film are shown in Table 2.

(Effects of the Invention) As explained above, the coating composition of the present invention uses a specific fluorine-containing organosilicon compound, so it has relatively high gloss, does not cause yellowing or deterioration of the coating film, and has good weather resistance. Patent applicant: Nissan Motor Corporation

Claims (1)

[Claims] 1. Synthetic resin (A) having one or more hydroxyl groups in the molecule
and an organosilicon compound (B) containing a perfluoroalkyl group and a hydrolyzable group bonded to a silicon atom and/or a hydroxyl group in the molecule, or a melamine resin for crosslinking (C) to this mixture. A coating composition comprising a mixture containing component (A) and 40 parts by weight or less of component (B) per 100 parts by weight of component (A).