JPS59196370A - Method for forming coating film - Google Patents

Abstract

PURPOSE:To obtain a coating film retaining excellent durable corrosion proofness and weather resistance over a long period of time, by applying a paint contg. a fluorocopolymer having hydroxyl groups as a base resin and a scaly metallic powder, and then applying a clear paint. CONSTITUTION:The surface of an article is coated with a paint contg. a fluorocopolymer having hydroxyl groups as the base resin component and a scaly metallic powder, and then with a clear paint. Preferred copolymers include a hydroxyl group-contg. fluorocopolymer contg. a fluoroolefin and cyclohexyl vinyl ether as structural components. A copolymer contg. 40-60mol% of a fluoroolefin, 5-45mol% of cyclohexyl vinyl ether, 5-45mol% of an alkylvinyl ether and 3-15mol% of a hydroxyalkylvinyl ether as essential structural components is particularly preferred.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a coating film with excellent corrosion resistance, weather resistance, etc.

In recent years, paints containing flaky metal powder have attracted attention as paints that provide excellent corrosion resistance and a coating appearance, and have come to be widely used for tanks, Zorant, land-based copper structures such as bridges, and automobile vehicles. It's here.

The above paint containing flaky metal powder is a paint containing flaky metal powder that generally uses acrylic resin, polyester resin, epoxy resin, etc. as the base resin.

In the conventional painting method, this paint is applied to the surface of the object to be painted, and then a clear paint is applied over the entire surface to form a paint film.

However, with conventional paint films containing scaly metal powder, sunlight passes through the top coat and reaches the base coat, so if exposed outdoors for a long period of time, the surface of the base coat deteriorates. , the interlayer adhesion between the undercoat film and the top coat film is reduced, coating film defects such as blisters and cracks are more likely to occur, and long-term durability is poor.As a result, protection,
There was a problem that the effect of beauty was reduced.

Therefore, a method has been adopted in which UV absorbers, light stabilizers, antioxidants, etc. are added to the paint to improve durability, but even with this method, a paint film with sufficient long-term durability cannot be obtained. The reality was that there was no such thing.

In view of the prior art as described above, it is an object of the present invention to provide an excellent method for forming a coating film with long-term durability, excellent corrosion resistance and weather resistance.

Such an object can be achieved by applying a paint containing a scale-like metal powder containing a hydroxyl group-containing fluorine-containing copolymer as a base resin component to the surface of the object to be coated, and then applying a clear paint.

According to the method of the present invention, by further improving the weather resistance of the undercoat film, a decrease in interlayer adhesion with the topcoat film is prevented, and the occurrence of wrinkles, blisters, cracks, etc. over a long period of time is avoided. The flaky metal powder-containing paint used in the present invention, which forms the undercoat film, contains as a base resin component a coating film with long-term durability and excellent corrosion resistance and weather resistance. Contains a fluorine-containing copolymer containing all hydroxyl groups so that a cured coating film can be obtained through a crosslinking reaction with a curing agent.

As the copolymer, a fluorine-containing copolymer containing a hydroxyl group and having a fluoroolefin and cyclohexyl vinyl ether as constituent components is desirable, and in particular
The copolymer described in OQ publication has not only good weather resistance but also
Since it has very low oxygen permeability and moisture permeability, it provides a coating M with excellent corrosion resistance, has good adhesion with various top coats, and is suitable because it can be cured at room temperature or by baking at a low temperature. It can be used for That is, the copolymers that can be suitably used in the present invention include fluoroolefins, cyclohexyl vinyl ethers, alkyl vinyl ethers, and hydroxyalkyl vinyl ethers as essential constituents in amounts of 0 to 60 mol%, 5 to daS mol%, and 5 to 7 tis mol, respectively. % and the ratio of 3 to /S mol%,
Preferably each 45~j; j;%le blade, / 0~3
0 Monosi X, 10-35 mol% and 5-73 mol%
The content is as follows.

Too low a fluoroolefin content is undesirable from the viewpoint of weather resistance. This causes inconvenience in terms of manufacturing.

Products with too high a fluoroolefin content also pose manufacturing difficulties. On the other hand, if the cyclohexyl vinyl ether content is too low, the hardness of the coating film will decrease, and if the alkyl vinyl ether content is too low, the flexibility will decrease, so both are not desirable.

Furthermore, it is particularly important that the hydroxyalkyl vinyl ether/'k be contained in the above-mentioned range from the viewpoint of completely improving the curability without impairing various useful properties as a coating paste.

If the hydroxyalkyl vinyl ether content is too high, the solubility of the copolymer changes and it becomes insoluble in certain substances such as alcohols, which limits its applicability as a solution-based paint paste. This is undesirable because it is unbalanced and reduces the flexibility of the cured coating. In addition, if the content is low, the effect of improving curability is lost, leading to a decrease in the solvent resistance of the cured coating film, and furthermore, causing disadvantages such as impairing the adhesion with the top coating film. So I don't like it.

As the fluoroolefin as a raw material for the fluorine-containing copolymer, it is preferable to use 9-haloolefin, particularly chlorotrifluoroethylene or tetrafluoroethylene. In addition, as the alkyl vinyl ether, it is preferable to use a straight chain TFC having a carbon number of a to g and one containing a branched argyl group, particularly one in which the number of carbon atoms in the argyl group is λ to λ. The fluorine-containing copolymer N'S may contain units based on comonomers other than the above seven essential components in an amount not exceeding 30 mol%. Such comonomers include olefins such as ethylene, propylene, and isobutylene, haloolefins such as vinyl chloride and vinylidene chloride, unsaturated carboxylic acid esters such as methyl methacrylate, vinyl acetate, vinyl n-butyrate, etc. Examples include carboxyl dispersion vinyls, unsaturated carboxylic acids such as fumaric acid, maleic acid, acrylic acid, and methacrylic acid.

The fluorine-containing copolymer has an intrinsic viscosity of 00! when measured at 30°C in a tetrahydro 7 run in an uncured state. ;
-20dl//;l, especially θ07~θgdi/17
, is preferable.

The above-mentioned fluorine-containing copolymers are produced by polymerization using a polymerization initiator such as a water-soluble initiator or an oil-soluble initiator or ionizing radiation in the presence or absence of a polymerization medium in a monomer mixture of a predetermined ratio. f) Manufactured by activating an initiating source to carry out a copolymerization reaction.

Examples of the hydroxyl group-containing fluorine-containing copolymer include Lumiflon LF100, Lumiflon LF200, Lumiflon L
F300, Lumiflon LF'lOθ (all brand names manufactured by Asahi Glass Co., Ltd.), etc. are commercially available.

A paint containing scale-like metal powder in which the entire base resin component is a hydroxyl group-containing fluorine-containing copolymer can be prepared according to a known method. That is, in an organic solvent solution of a fluorine-containing copolymer containing a hydroxyl group, a curing agent, a scaly metal powder, and, if necessary, various coloring pigments, additives, modifiers, etc. commonly used for paints are added. By dispersing the scaly metal powder, a paint containing scaly metal powder can be obtained.

Examples of the organic solvent include aromatic hydrocarbons such as xylene and toluene, alcohols such as n-butano, esters such as butyl acetate, ketones such as methyl isobutyl ketone, and glycol ethers such as ethyl cellosolve. In addition to the above, various commercially available thinners can also be used.

Further, as the curing agent, in the case of a room temperature curing type, a polyvalent incyanate having two or more isocyanate groups in the molecule is suitable.

The polyvalent isocyanate includes aliphatic or alicyclic isocyanates such as hexamethylene diisocyanate, tetramethylene diisocyanate, inphorone diisocyanate, hydrogenated diphenylene diisocyanate, and hydrogenated xylylene diisocyanate, or biuret forms and dimers thereof. , Sangatsuichii, or a reaction compound of an excess of these isocyanate compounds with a low-molecular polyol such as ethylene glycol, glycerin, trimethylolpropane, or pentaerythritol. Needless to say, in the case of a room-temperature curing type, the curing agent becomes a two-component paint, in which the curing agent is mixed with the hydroxyl group-containing fluorine-containing copolymer solution as the main ingredient before coating.

In addition, in the case of the pyrolysis type, block incyanate is obtained by masking the above polyvalent incyanate with a masking agent such as phenols, a) V-cols, oximes, lactams, amines, or amides; melamine; Typical examples include a curing agent such as a condensation product of an amine compound such as urea, benzoguanamine, or acetoguanamine and an aldehyde compound, or an aminoplast resin obtained by further etherifying the condensation product with an alcohol such as butanol.

Furthermore, as the flaky metal powder used in the above-mentioned flaky metal powder-containing paint, those normally used in flaky metal powder-containing paints can be used, such as flaky aluminum powder, copper powder, bronze powder, iron oxide powder, etc. Examples include powder, mica powder treated with titanium oxide, etc. As for the particle size of the scaly metal powder, an average particle size of 3 to 30 microns is generally suitable.

In addition, if necessary, various inorganic or organic coloring pigments such as titanium oxide, carbon black, and phthalocyanine, or anticorrosion pigments, ultraviolet absorbers, and surface conditioners may be added to the paint containing scaly metal powder used in the present invention. Modifier: A modifier such as cellulose acetate butyrate can be added as appropriate.

The blending ratio of the components constituting these flaky metal powder-containing paints can be varied over a wide range depending on the coating conditions, etc., but usually the total amount of the fluorine-containing copolymer containing hydroxyl groups and the curing agent in the paint is 20. Appropriate values are ~4t0 weight% and scale-like metal powder bottom/~0% by weight.

Next, as the clear paint used in the present invention, acrylic resin paints, oil-free polyester resin paints, or alkyd resin paints, which are used as top coats for general flaky metal powder-containing paint coatings, can be used. .

In the case of acrylic resin paints, a vinyl copolymer having hydroxyl groups and/or carboxyl groups is used as the base resin. Specifically, ethylenic monomers having a hydroxyl group such as hydroxybutyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, and N-methylol (meth)acrylamide; (meth) Ethylene monomers having a carboxyl group such as acrylic acid, crotonic acid, itaconic acid, maleic acid; aromatic vinyl monomers such as styrene, vinyltoluene, benzyl (meth)acrylate; methyl (meth)acrylate, (meth)acrylate; Ester monomers such as ethyl acrylate, butyl (meth)acrylate, ethylhexyl (meth)acrylate, octyl (meth)acrylate, dimethyl itaconate, dimethyl maleate, dimethyl fumarate; other (meth)acrylonitrile, vinyl acetate ( It is a product obtained by copolymerizing honorific monomers such as meth)acrylamide using a normal solution polymerization method.In addition, in the case of oil-free polyester resin paints, ethylene glycol, propylene glycol, diethylene glycol, 1) Polyhydric alcohol components such as kohl, dimethylprono(diol, g1nose1one, trimethylolethane, trimethylolpronoethane, hegysantriol, pentaeryth1notol, sorbitol, dipenequerith1notol) and phthalic anhydride, inphthalic acid Synthesized with polybasic acid components such as acid, trimellitic anhydride, maleic anhydride, )-fA[, succinic acid, adipic acid, and 7) succinic acid by conventional melt condensation method, azeotropic condensation method, etc. material as the base resin.

In the case of alkyd resin-based paints, the base material is the polyester resin modified with castor oil, tung oil, safflower oil, soybean oil, linseed oil, coconut oil, cottonseed oil, tall oil, olive oil, or their fats, such as dicarboxylic acid. Use resin.

The above-mentioned clear paint consists of these base resins and the same organic solvents, curing agents, additives, modifiers, etc. as those used in the above-mentioned scale-like metal powder-containing paint, and if necessary,
A color clear can also be made by blending a small amount of inorganic or organic coloring pigment or organic coloring dye.

Next, the coating film forming method of the present invention can be carried out by a conventional method. That is, a paint containing scale-like metal powder is applied to the surface of a steel plate, aluminum plate, etc., which has been surface-treated or previously treated with Zolaimer, Surfazer, etc., as necessary, and diluted with an organic solvent for viscosity of 10 to 30 seconds ( The temperature of the coating was adjusted to (F-#-'l/20°C), and the coating was applied to the surface of the object to give a dry film thickness of 70 to 30μ.

Next, the clear paint is adjusted to have a viscosity of 75 to tO seconds (Ford cup - +4t/20°C) with a diluting organic solvent as required, and coated to give a dry film thickness of 10 to 1IOμ.

As for the coating method, ordinary spray coating, electrostatic coating, etc. are used for both the flaky gold powder paint and the clear paint, but there are no particular restrictions on other coating methods.

In addition, in the present invention, the clear paint can be overcoated over the paint film containing the flaky metal powder whether it is in an undried state or in a dry state. . In other words, if the clear paint film containing flaky metal powder is coated over and over again when it is still wet,
Leave it on for about 20 minutes and then apply another coat. In addition, when applying clear paint after the paint film containing scale-like metal powder has dried, if the paint containing scale-like metal powder is a room-temperature curing type, leave it for about 24 hours or more, or force dry it. In the case of a bake-curing type, apply multiple coats after baking and hardening. In addition,
73 θ to 77 θ to 77 θ to 77 θ to 77 θ to 77
It can be baked and hardened at 0°C for 20 to 30 minutes.

As mentioned above, the weather resistance of the undercoat film containing scaly metal powder in the paint film formed by the uninvented method is extremely poor, so that the difference between the eyebrows of the undercoat film and the top coat film as in the past Disadvantages such as reduced adhesion are eliminated, and as a result, the coating film can protect the object to be coated and maintain its aesthetic appearance for a long period of time.

In addition, after applying a paint containing scale-like metal powder that uses a conventional acrylic resin or polyester resin as a base resin component, a clear paint that uses a hydroxyl group-containing fluorine-containing copolymer as a base resin component is applied. When the paint film obtained by painting is exposed outdoors for a long period of time, even if the clear paint film has excellent weather resistance, sunlight passes through the clear paint film, resulting in the formation of scaly metal powder, which is the base coat film. Since the surface of the containing paint coating film deteriorates, the durability is inferior to that of the coating film obtained by the method of the present invention.

The details of the present invention will be explained below with reference to Examples. Note that "parts" and "%" indicate "parts by weight" and "% by weight," respectively.

The paints containing scale-like metal powder and the clear paints had the formulations shown in Tables 1 and 2, respectively.

Note/) Paint I, II, ■ “Lumiflon LF-, 200” (Product name manufactured by Asahi Glass Co., Ltd.)
[Solid content 50%, hydroxyl value j2 (solid content), acid value 0] Paint ■ "Lumiflon LF-G00" (product name manufactured by Asahi Glass Co., Ltd.) [
Solid content SO%, hydroxyl value 4t7 (solid content), acid value S (solid content)] Note, 2) Paint ■
, ■, D, E "Acridic Hachito 07" (trade name manufactured by Dainippon Ink and Chemicals Co., Ltd.) [Solid content SO%, hydroxyl value 50 (pheno)
] Paint■ "Acridic 7-?/Ω" (trade name manufactured by Dainippon Ink and Chemicals Co., Ltd.) [°Solid content SO%, hydroxyl value 2g <pheno), acid value 5 (pheno)] Paint C "Acridic 4L Dar/79Jf Inu Nippon Ink Chemical Industry Co., Ltd. (trade name) [solid content, 30%, hydroxyl value, 2.2
+ Varnishin, acid value S (pheno)] Note 3) Paint ■, B "Beracolite Ml, 2011-3O8J (trade name manufactured by Inu Nippon Ink Chemical Industry Co., Ltd.) [Solid content SO%, hydroxyl value 2S (pheno), acid Pheno] Note 4t) Paint I, V "Dismodule N-ri 5J (Bayer R product name) [Billet type hexamethylene diisocyanate prepolymer, solid content 75%, NC 0% 20] Paint ■ “Takenate D/1lON” (Product name manufactured by Shikinichi Yakuhin Kogyo Co., Ltd.) [Inphoron diisocyanate prepolymer, solid content 75%, NCO%/θ5] Note 5) Paint ■, ■, E “Coronate DC272!tJ (Japan Product name manufactured by Polyurethane Kogyo Co., Ltd.) [Hexamethylene diisocyanate-based prepolymer pace block incyanate, solid content and 0%, effective NCO% // 6] Note 6) Paint ■, ■, ■, B, C [Suit Ya-Betsukamine J-g,,20-1.O] (Dainippon Ink Chemical Industry Co., Ltd. product name) [Solid content 60%] Note 7) "Albase l-/109tVIJ (Toyo Aluminum Co., Ltd. product name) Note g) Paint A "Burnock DE-/G0-') OJ (trade name manufactured by Inu Nippon Ink Chemical Industry Co., Ltd.) [Solid content 7θ%, hydroxyl value 9 & (varnish), acid value 3 (varnish)] Note) Paint A, D "Dismodule L-, ll'J (product name manufactured by Bayer AG) [hegisamethylene diisocyanate fl/
yP! Rimmer, solid content 90%, NC 0% -〇〇〕 Example/ Dry film thickness of paint I containing scaly metal powder on dull steel plate with electrodeposited coating and alkyd-melamine resin coating.
After setting for 1S minutes, a clear paint was spray-painted to a dry film thickness of 30 μm and left to dry for 7 days.

Comparative Example The entire coating film was formed in the same manner as in Example except that paint V containing flaky metal powder was used instead of paint I containing flaky metal powder.

Example: A paint containing scale-like metal powder ■ was spray-painted on a taromate-treated aluminum plate to a dry film thickness of 0μ.
After forced drying at gθ℃ for -θ minutes, clear paint A'
(Spray paint to dry M thickness 30μ, 700
It was baked and dried at ℃ for 20 minutes.

Example 3 A chromate-treated aluminum plate was spray-painted with a paint containing flaky metal powder to a dry film thickness of 2Sμ,
After baking and drying at 750℃ for 20 minutes, clear paint E
Spray paint to a dry film thickness of 30μ and heat at 760°C.
, and baked dry for 20 minutes.

COMPARATIVE EXAMPLE A coating film was formed in the same manner as in Example 3, except that paint containing flaky metal powder (2) was used instead of paint (2) containing flaky metal powder.

Example: Glychromate-treated aluminum plate K 114 Paint containing flaky gold maple powder ■ was spray-painted to a dry film thickness of 20μ, and after forced drying at 700°C for S minutes, clear paint C was applied to a dry film thickness of 30μ. Spray painted to make it look like a bird, 7
It was baked and dried at 50°C for 20 minutes.

Comparative Example 3 A coating film was formed in the same manner as in Example D, except that the coating material containing scaly metal powder (2) was used instead of the coating material (2) containing the scaly metal powder.

Example S A coating film was formed in the same manner as in Example D except that clear paint B was used instead of clear paint C.

Comparative Example A coating film was formed in the same manner as in Example 5, except that the coating material containing scaly metal powder (2) was used instead of the coating material (2) containing scaly metal powder.

The coating film appearance, gloss, adhesion, and hot water resistance of the test plates obtained in Examples/- 5 and Comparative Examples/-- were tested before, 2000 hours after and 3.
Tests were conducted for each after θOO time, and the results are shown in Table 3.

As is clear from Table 3, the coating film obtained by the method of the present invention has excellent coating performance. On the other hand, the coating films obtained in comparative examples using conventional acrylic resin-based and polyester-based coatings containing flaky metal powder had excellent coating performance at the initial stage; After the weather off-season test, the coating performance deteriorated.

Claims (1)

[Claims] After coating the surface of the object with a paint containing scaly gold rice powder containing a base resin component of the hydroxyl base A-1, a fluorine-containing copolymer, a clear paint'(c-coating)'fc-characteristic coating film How to form.