JPS5883034A - 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 silicones and a metallic pigment covering the surface of particles with a polymer formed from a compd. having a polymerizable double bond. CONSTITUTION:At least one selected from the group consisting of an epoxy- modified silicone oil, carboxyl-modified silicone oil, silicone resin, and dimethyl silicone oil, is added to a coating compsn. for plastic covering which contains a metallic flake pigment compsn. covering the surface of metallic flake pigment particles, in a ratio of 0.1-30pts.wt. said compsn. based on 100pts.wt. metal moiety of said metallic flake pigment, with a polymer formed by the reaction of a compd. having a polymerizable double bond. The employed metallic flake pigments 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 industrial fields, including housing materials, daily necessities, machine parts, and industrial materials, and demand for them continues to increase. Therefore, surface coating is performed for the purpose of internal protection and decoration, and paints containing metal powder pigments are also often used to give a metallic feel. However, in the case of plastic paint bases, the paint film dries at low temperatures (typically 50 to This can only be done at a temperature of about 60°C), and it is important to be careful in selecting the solvent and resin. In particular, when painting paints containing metal powder pigments such as aluminum pigments, the metal powder pigments are rougher than other general pigments, and baking is impossible, and the compatibility between the metal powder pigment surface and the paint resin is poor. For bad etc.
The cohesive strength of the paint film is extremely reduced, and the paint film is often destroyed when the attached label is removed, resulting in a loss of commercial value. Therefore, in order to prevent such undesirable phenomena, conventional efforts have been made to reduce the amount of metal powder pigment added, or to improve the wettability between metal powder pigment and resin by heating/aging the paint or treating it with additives. Countermeasures have been attempted, such as removing fatty acids adsorbed on the surface of metal powder pigments, but these have resulted in low F feeling, a significant increase in manufacturing costs, and physical properties such as stability of metal pigments or paints. Due to the negative effects on the environment, no satisfactory solution has yet been found.

Furthermore, in the case of coatings containing metal pigments, particularly aluminum pigments, traces of sweat may become white, reducing commercial value. The details of this phenomenon are unknown, but it is thought that the physical properties of the paint film are insufficient (baking cannot be painted), and corrosion of the aluminum surface causes the paint film to crack and turn white. In order to prevent this, various attempts have been made to select paint resins and improve them with additives.
Other properties of the coating film deteriorated and sufficient effects were not obtained.

This invention was made to overcome the current situation, and uses a polymer produced by reacting a compound having a polymerizable double bond to coat the surface of a metal powder pigment particle with a metal content ioo parts by weight (by weight) of the metal powder pigment. On the other hand, in a plastic coating composition containing the coated metal powder pigment composition, at least 0.1 to 30 parts by weight of epoxy-modified silicone oil, carboxyl-modified silicone oil, silicone resin, and dimethyl silicone oil are added. The object of the present invention is to provide a coating composition for plastic coating, which is characterized in that it contains one of the following.The details of 1 will be 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 carbonyl mill method, a wet ball mill method, an attritor method, etc. It is.

In addition, the compounds having polymerizable double bonds used in this invention include styrene, α-methylstyrene, vinyltoluene, acrylonitrile, methacrylic acid, vinyl acetate, vinyl propionate, acrylic acid, acrylic acid. Ester, methacrylic acid, methacrylic ester, crotonic acid, itaconic acid, citraconic acid, oleic acid, maleic acid, maleic anhydride, 1,6-hexanediol diacrylate, 1,4-butanediol diacrylate, divinylbenzene, epoxy 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, hydroxyethyl acrylate, cyclohexyl acrylate, etc., and methacrylic esters include methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, stearyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, glycidyl methacrylate, methoxyethyl methacrylate,
Examples include butoxyethyl methacrylate and cyclohexyl methacrylate. These may be used alone or in a mixture of two or more.

Next, the surface of the metal powder pigment is coated with a polymer (this is called B) of a compound (this is called A) having such a polymerizable double bond. In order to recover, A is 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 A is soluble and B is substantially insoluble. However, the organic solvents to be removed include aliphatic hydrocarbons such as hexane, heptane, octane, cyclohexane, and mineral spirits, aromatic hydrocarbons such as benzene, toluene, and xylene, chlorobenzene, trichlorobenzene,
Halogenated hydrocarbons such as perchlorethylene and trichlorethylene, alcohols such as methanol, ethanol, n-propyl alcohol and n-butanol, ketones such as 2-propanone and 2-butanone, esters such as ethyl acetate and propyl acetate, tetrahydrofuran , diethyl ether, ethyl propyl ether, etc., and the polymerization initiator is an organic peroxide such as t-butyl peroxide, acetyl peroxide, benzoyl peroxide, lauroyl peroxide, cumyl peroxide, etc. Oxides, azo compounds such as α,α'-azobisisobutyronitrile may be used. The polymerization reaction temperature is preferably in the range of 60 to 200°C; temperatures outside this range are undesirable because the reaction time is long and the efficiency of the polymerization initiator is low. Preferably in inert gas.

By the method described above, the amount of the polymer coated on the surface of the metal powder pigment particles is 0.1 to 30 parts by weight based on 100 parts of the metal content of the metal powder pigment, from the viewpoint of peeling resistance. is preferred. This is because if it is less than 0.1 part by weight, sufficient coating cannot be achieved, and if it exceeds 30 parts by weight, the performance will not be particularly improved and the manufacturing cost will simply increase.

The silicones of this invention may be added by either a method of kneading them into the resin-coated pigment paste in advance, or a method of adding one silicone at the time of preparing the paint. The amount is preferably 0.5 to 5 parts by weight based on 100 parts by weight of the nonvolatile content of the resin-coated pigment. Because 0.
If the amount is less than 5 parts by weight, the effect will be insufficient, and if it exceeds 5 parts by weight, the printability of the resulting coating film will be impaired.

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 will only deteriorate the physical properties of the coating film and will not be recognized as a special point.

Next, when preparing a paint for plastic painting, it is necessary to select the resin component appropriately depending on the base material. A mixture of isobutanol, n-butanol, isopropyl alcohol, ethyl cellosolve, butyl cellosolve, dioxane, cyclohexane, ethyl acetate, etc. or a mixture thereof may be used, depending on the solubility in the base material. Leveling agent, according to
Organic pigments, plasticizers, etc. may be added, but in any case, the above-mentioned resins and solvents may be mixed in a conventional manner.

Examples of glue are shown below.

[Example 1] In a 2-liter four-bottle flask, 2.0 g of epoxidized polybutadiene, 1.1 g of 1.6-hexanediol diacrylate, 0.6 g of acrylic acid 1 1010 g of Minerals Beer Lit, aluminum paste (Toyo Aluminum Co., Ltd.) manufactured by Alpaste MG-1000, a registered trademark.
, non-volatile content 71.3%), and stirred and mixed while introducing nitrogen gas. After raising the temperature in the system to 80°C, 1 g of α, α'-azobisisobutyronitrile was added and the reaction was maintained at 80°C for 6 hours. After finishing the reaction, the mixture was filtered and concentrated. A resin-coated aluminum paste was obtained. Analysis of this shows that the resin-coated aluminum content is 7
It was rumored to be 0.3.

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 component was dissolved and filtered in step 2), the remaining resin component was filtered, dried, and weighed, it was found that 0.4 parts by weight were coated on 100 parts by weight of aluminum.

To 1 piece of this resin-coated aluminum paste, 100 parts by weight of resin-coated aluminum, 1.5 parts by weight of epoxy-modified silicone oil (Toshi Silicone Co., Ltd. 11.5 parts by weight)
F8411) and mineral spirit were added and mixed uniformly to obtain a resin-coated aluminum paste with a non-volatile content of 65.3%.

[Example 2] Reactive seed potatoes equipped with a 20 liter stirring device, 34 g of methyl methacrylate, 17 g of 1,6-hexanediol diacrylate, 10 g of acrylic acid, 10,100 g of mineral spirits, aluminum paste (same product as in Example 1) ) 2500g, and then the same operation as in Example 1 was carried out.
(α,α′-azobisisobutyronitrile is 1°Og)
A resin-coated aluminum paste was obtained. The aluminum content was 70.5%, and the amount of coating resin was 1.7 parts by weight per 100 parts by weight of aluminum.

Carboxyl-modified silicone oil (manufactured by Toshi Silicone Co., Ltd.,
5F8418) to resin-coated aluminum 100 parts by weight 1
To this, 1.5 parts by weight and mineral spirit were added and mixed uniformly to obtain an aluminum paste with a non-volatile content of 64.8.

[Example 3] Resin-coated aluminum paste 40 obtained in Example 2
1.5 parts by weight of dimethyl silicone oil (manufactured by Toshi Silicone Co., Ltd., 5H200, 100 centistokes) and mineral spirit were added to 100 parts by weight of resin-coated aluminum and mixed uniformly to obtain a non-volatile content of 65%.
．． A 1% aluminum paste was obtained.

[Example 4] Instead of dimethyl silicone oil in Example 3,
Silicone resin (manufactured by Toshi Silicone Co., Ltd., 5R2400
) was used, except that an aluminum paste with a nonvolatile content of 64.3% was obtained in exactly the same manner as in Example 3.

[Example 5] Resin-coated aluminum paste 40 obtained in Example 2
To 0 g, 4 parts by weight of epoxy-modified silicone oil (same product as shown in Example 1) for 100 parts by weight of resin-coated aluminum and mineral spirit were added and mixed uniformly to obtain a mixture with a non-volatile content of 65.7 g. An aluminum paste was obtained.

[Comparative example]

The amount of epoxy-modified silicone oil in Example 51 was 0.3 ff per 100 parts by weight of resin-coated aluminum.
An aluminum paste with a non-volatile content of 64.5% was obtained in exactly the same manner as in Example 5, except that the amount was changed to i parts.

[Example 6] The resin-coated aluminum pastes obtained in Examples 1 to 5 and Comparative Examples above and untreated aluminum paste (Alheest MG-1000 manufactured by Toyo Aluminum Co., Ltd.)
．． A plastic coating paint was prepared with the following composition (non-volatile content: 71.3%), and each was spray-coated on one polystyrene coated plate, dried for 20 minutes at 50'C, and then coated with a film thickness of 10μ.
Two coated plates were prepared for each. The paint composition was acrylic lacquer (manufactured by Nippon Reichhold Co., Ltd., Acridic A-165, solid content 45%) at 35%, aluminum paste at 5% in terms of non-volatile content, and solvent (ethyl acetate: ethyl cellosolve: cyclohexane = 40: 30:30) /
The ratio (weight ratio) is 62.

One of the obtained coated plates was subjected to a peeling test using a paint tape, and the other coated plate was peeled off at 40°C by touching the coated film with a sweaty finger. Atmosphere F with a relative humidity of 90 degrees Celsius (left for 10 days, then wiped off the area touched by the finger with a cloth, examined the degree of discoloration (whitening) of that area, and summarized the results in a table.

As is clear from the table, the coating composition of the present invention was excellent in both the peeling test and the degree of discoloration.

Claims (1)

[Claims] The surface of the metal powder pigment particles is coated with a polymer produced by reacting a compound having a polymerizable double bond at a ratio of 0.1 to 30 parts by weight based on 100 parts by weight of the metal content of the metal powder pigment.
A plastic coating comprising at least one of epoxy-modified silicone oil, carboxyl-modified silicone oil, silicone resin, and dimethyl silicone oil in a plastic coating composition containing a coated metal powder pigment composition. Paint composition for use.