JPS5883033A - Coating composition for plastic covering - Google Patents

Abstract

PURPOSE:To obtain the titled coating providing an improved separating condition in stripping labels, etc. from a coating film, by adding to a coating a metallic pigment covering the surface of metallic flake pigment particles with a polymer obtd. by the reaction of a compd. having a polymerizable double bond with the metal moiety of the pigment. CONSTITUTION:To a coating is added a metallic pigment compsn. covering the surface of a metallic flake pigment with 0.1-1pts.wt. polymer obtd. by the reaction of a compd. having a polymerizable double bond with 100pts.wt. metal moiety of the metallic flake pigment. For coating the surface of the metallic flake pigment with the polymer (B) of a compd. (A) having a polymerizable double bond, (A) may be polymerized in an org. solvent in which (A) is soluble and (B) is insoluble, to form a coating of component (B) on the surface of the metallic flake pigment in the presence of a polymn. initiator. The preferred metallic flake pigment include aluminum, copper, zinc, iron, nickel, etc., and alloys of these metals.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention aims to prevent the peeling phenomenon that occurs when a label or the like is peeled off from a paint film due to a reduction in the cohesive force of the paint film by incorporating a metal pigment into the plastic. The present invention relates to a coating composition for painting.

Plastics are used in a wide variety of industries, including housing materials, daily necessities, machine parts, and industrial materials, and the demand for plastics continues to increase. Surface painting is performed for the purpose of interior protection and decoration, and paints containing gold and quince pigments are also often used to give a metallic feel.However, in plastic painting, the heat resistance of the material, Due to drawbacks such as poor solvent resistance and poor adhesion to paint materials, paint films can only be dried at low temperatures (generally around 50 to 60'C), making it difficult to select solvents and resins. In particular, when painting paints containing metal powder pigments such as aluminum pigments, metal powder pigments are coarser than other general pigments, and baking is impossible. , due to poor compatibility between the surface of the metal powder pigment and the paint resin, the cohesive force of the paint film is greatly reduced, causing destruction of the paint film when the attached label is removed, which impairs the product value. Therefore, in order to prevent such undesirable phenomena, conventional methods have been to reduce the amount of metal powder pigment added, or to reduce the wettability of metal powder pigment and resin by heating aging treatment of paint or additive treatment. Attempts have been made to improve the properties of metallic pigments or to remove fatty acids adsorbed on the surface of metallic powder pigments, but these efforts have resulted in a decrease in the metallic feel, a significant increase in manufacturing costs, and problems with the stability of metallic pigments or paints. No satisfactory solution has yet been found due to the adverse effects on physical properties.

This invention has been made in view of the current situation, and uses 0.1 parts by weight or more obtained by reacting a compound having a polymerizable double bond with 100 parts by weight of the metal content of a metal powder pigment. The present invention provides a coating composition for coating plastics, characterized in that it contains a metal pigment composition in which the surfaces of metal powder pigment particles are coated with less than 1 part by weight of a polymer.

The details are described below.

First, the metal powder pigment of the present invention is a flake powder pigment made of aluminum, copper, zinc, iron, nickel, etc. or alloys thereof, which is usually produced by a dry ball mill method, a wet ball mill method, an attritor method, etc. It is.

In addition, the compounds having a polymerizable double bond used in this invention include styrene, α-methylstyrene, vinyltoluene, acrylonitrile, methacrylnitrile, vinyl acetate, vinyl propionate, acrylic acid, acrylic ester, methacrylate. Acid, methacrylic acid ester, crotonic acid, iconic acid, citraconic acid, oleic acid, maleic acid, maleic anhydride, l,6-hexanediol diacrylate, 1,4-butanediol diacrylate, divinylbenzene, epoxidized polybutadiene, Examples include cyclohexene vinyl monoxide, divinylbenzene monoxide, etc., and examples of acrylic esters include methyl acrylate, ethyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, stearyl acrylate, Hydroxyethyl acrylate, hydroxypropyl acrylate, glycidyl acrylate, methoxyethyl acrylate, bitoxyethyl acrylate, cyclohexyl acrylate, etc., and as methacrylate ester, ethyl methacrylate, ethyl methacrylate, n-butyl meccrylate, etc. , 2-ethylhexyl methacrylate, lauryl methacrylate, lauryl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, glycidyl methacrylate, methoxyethyl methacrylate, butoxyethyl methacrylate, cyclohexyl methacrylate, and the like. These may be used alone or in a mixture of two or more.

Next, in order to coat the surface of the metal powder pigment with a polymer (this is called B) of a compound (this is called A) having such a polymerizable double bond, A is soluble and B is soluble. A may be polymerized to form a film of B on the surface of the metal powder pigment in the presence of a polymerization initiator in an organic solvent in which B is substantially insoluble. , heptane,
Aliphatic hydrocarbons such as octane, cyclohexane and mineral spirits, aromatic hydrocarbons such as benzene, toluene and xylene, halogenated hydrocarbons such as chlorobenzene, trichlorobenzene, perchloroethylene and trichlorethylene, methanol, ethanol, n- Any of alcohols such as propyl alcohol and n-7'tanol, ketones such as 2-pronocorone and 2-7'tanone, esters such as ethyl acetate and propyl acetate, and ethers such as tetrahydrofuran, diethyl ether and ethylpropyl ether. In addition, the polymerization initiator includes organic peroxides such as butyl peroxide, acetyl peroxide, benzoyl peroxide, lauroyl peroxide, and cumyl peroxide, α, α′-azobisisobutyronitrile, etc. An azo compound such as may be used. The polymerization reaction temperature is preferably in the range of 60 to 200°C; temperatures outside this range are unfavorable because the reaction time is long and the efficiency of the polymerization initiator is low. Preferably in inert gas.

By the above method, the amount of the polymer coated on the particle surface of the metal powder pigment is 0.1 part by weight or more based on 100 parts by weight of the metal content of the metal powder pigment, from the viewpoint of peeling resistance. Further, from the viewpoint of improving the color tone, it is preferable that the amount is less than 1 part by weight.

The amount of the metal pigment composition thus obtained to be added to the paint is preferably 1 to 60 parts by weight based on 100 parts by weight of the resin solid content in the paint. This is because if it is less than 1 part by weight, the desired metallic feel cannot be obtained, and if it exceeds 60 parts by weight, it only deteriorates the physical properties of the coating and no particular advantage is observed.

Next, when preparing a paint for plastic painting, the resin component must be selected appropriately depending on the base material, but acrylic, urethane, alkyd, nitrocellulose, epoxy, vinyl, or any of these The mixture, and the solvent has a relationship with the solubility in the base material, but inbutanol, n-butanol, isopropyl alcohol, ethyl cellosolve, butyl cellosolve, dioxane, cyclohexane, ethyl acetate, etc., or mixtures thereof, etc. Leveling and cutting as necessary,
Organic pigments, plasticizers, etc. may be added, but in any case, the above-mentioned resin and solvent may be mixed in accordance with a conventional method.

Examples are shown below.

[Example 1] In a 2-liter four-bottle flask, 2.0 g of epoxidized polybutadiene, 1.0 g of 1.6-hexanediol diacrylate, 0.6 g of acrylic acid, 980 g of mineral spirit, and aluminum paste (manufactured by Toyo Aluminum Co., Ltd.) were added. , registered trademark Alpaste 1200 M, metal content 65.0%) was added, and the mixture was stirred and mixed while introducing nitrogen gas. After raising the system temperature to 80℃, α
, 1 g of α'-azobisisobutyronitrile was added, 8
The mixture was reacted for 6 hours while being maintained at 0°C, and after the reaction was completed, the mixture was filtered and concentrated to obtain a resin-coated aluminum paste. When this was analyzed, the resin-coated aluminum content was 61.0%.

This resin-coated aluminum paste was washed and filtered with n-hexane, powdered, and mixed acid (hydrochloric acid: nitric acid: water = 1:1
When the aluminum content was dissolved and filtered in step 2), and the remaining resin content was filtered and dried and weighed, it was found that 0.3 parts by weight were coated with respect to 100 parts by weight of aluminum.

[Example 2] In a 2-liter fourth flask, 3.0 g of methyl methacrylate and 1 part of 1,6-hexanediol diacrylate were added.
．． 5g, acrylic acid 0.9g1 Mineral Spirit 9
80 g, aluminum paste (same product as Example 1)
280 g was added, and the same operations as in Example 1 were carried out to obtain a resin-coated aluminum paste. The aluminum content was 59.0%, and the amount of coating resin was 0.8 parts by weight per 100 parts by weight of aluminum.

[Example 3] In a 2-liter four-loaf flask, 3.4 g of methyl methacrylate, 1.7 g of 1.6-g of bovine diol diacrylate, 1 og of acrylic acid, 980 g of mineral spirit, and aluminum paste (as in Example 1) were added. 280g of the same product) was added, and the same operation as in Example 1 was carried out to obtain an aluminum content of 57.3'la and a resin amount of 1.
7 parts by weight (based on 100 parts by weight of aluminum) of resin-coated aluminum paste was obtained.

[Example 4] Plastic coating paints were prepared using the resin-coated aluminum pastes obtained in Examples 1 to 3 and untreated aluminum pastes (same as in Example 1) with the following composition, and each was spray-painted on a polystyrene coated plate. After drying at 50° C. for 20 minutes, a coated plate with a film thickness of 10 μm was prepared. The paint composition is acrylic lacquer (manufactured by Nippon Reichhold).
Product name Acridic A-165, solid content 45%) 35
, aluminum paste in terms of non-volatile content: 5, solvent (ethyl acetate: ethyl cellosolve: cyclohexane = 40:
30:30) to 62 (weight ratio), and the resulting coating film on the coated plate was subjected to a peel test using cellophane tape, and the results and the color tone of the coated plate are summarized in the table. As is clear from this table, the color tone of the paint using the resin-coated aluminum paste obtained in Example 3 is good (
Although there were some difficulties (no problems in practical use), the peel test results obtained in all Examples were all excellent.

Claims (1)

[Claims] The surface of the metal powder pigment particles is coated with 0.1 part by weight or more and less than 1 part by weight of a polymer obtained by reacting a compound having a polymerizable double bond with 100 parts by weight of the metal content of the metal powder pigment. A paint composition for painting plastics, characterized by containing a metal pigment composition.