JPH0141664B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an epoxy resin coating composition containing an aluminum pigment with improved leafing properties and excellent weather resistance and rust prevention properties. In general, leafing type aluminum pigment-containing epoxy resin paints have been used in a wide variety of applications, including steel towers, bridges, tanks, and vehicles. However, conventional leafing-type aluminum pigment-containing epoxy resin paints do not necessarily provide coatings with satisfactory leafing properties, resulting in poor coating appearance and poor weather resistance. In view of the above-mentioned current situation, the present invention aims to provide an epoxy resin coating composition containing aluminum pigment, which has excellent leafing properties of aluminum pigment. Such an object is achieved by a leafing-type aluminum pigment-containing epoxy resin coating composition, which is characterized by containing flaky mica with a major axis of about 1 to 20 μm. be done. The coating film obtained using the coating composition of the present invention has good leafing properties, and an overlapping layer of aluminum flakes is formed on the coating film surface. A coating film is obtained. Therefore, the aluminum pigment-containing epoxy resin coating composition of the present invention can be used not only as an undercoat, but also as an undercoat.
Since it functions as a top coat, it can serve as both an undercoat and a topcoat in one go, which also shortens the painting process. The aluminum pigment-containing epoxy resin coating composition of the present invention contains an epoxy resin, a curing agent,
It consists of a leafing type aluminum pigment, scaly mica, and a solvent, and further contains a rust preventive pigment, an extender pigment, and various additives as necessary. As the epoxy resin, ordinary epoxy resins for paints can be used. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, etc. can be typically used. In particular, bisphenol F type epoxy resin has a low viscosity, so the amount of solvent in the paint can be reduced accordingly, making it possible to create a high non-volatile content paint, allowing for thick film coating, and also improving the leafing properties of aluminum pigments, making it ideal. Commercially available bisphenol F-type epoxy resins include Epicron #830 (manufactured by Dainippon Ink and Chemicals) and Epomiku R-140 (manufactured by Mitsui Petrochemical Industries, Ltd.). As the curing agent, a normal curing agent for epoxy resins can be used. For example, aliphatic polyamines such as diethylenetriamine and triethylenetetraamine, and aromatic polyamines such as metaphenylenediamine and diaminodiphenylmethane can be typically used. In particular, the use of aromatic polyamines is optimal because a coating film with good adhesion can be obtained even on metal substrates that have been treated to a low degree. Commercially available products include Sanmide M
(manufactured by Sanwa Kagaku Kogyo Co., Ltd.), TH-431, 432, 452 (manufactured by Toto Kasei Co., Ltd.), and Adeka Hardener EH (manufactured by Asahi Denka Kogyo Co., Ltd.) are representative examples. As the leafing type aluminum pigment, those commonly used in this type of paint can be used. In particular, paste-like products whose surface has been treated with stearic acid etc. are good, such as Altop Sap (manufactured by Tokai Kinzoku Co., Ltd.), Aluminum Paste Sap (manufactured by Showa Aluminum Powder Co., Ltd.), Alpaste (manufactured by Toyo Aluminum Co., Ltd.), and Eterna Bright (Silver Line). Commercial products such as Stapa (manufactured by Asahi Kasei Industries, Ltd.) and Stapa (manufactured by Asahi Kasei Industries, Ltd.) can be used. Suitable scaly mica has a long axis of about 1 to 20 μm. If the long axis of scaly mica is smaller than the above range, it will not contribute to improving the leafing properties of aluminum pigments, and conversely, if it is too large, the surface of the coating will become rough, the appearance of the coating will be poor, and the leafing properties of aluminum pigments will deteriorate. This is not appropriate because the effect of improving the ing property will be small. Examples of solvents include hydrocarbon solvents such as toluene and xylene, ester solvents such as ethyl acetate and butyl acetate, ether solvents such as cellosolve, methyl ethyl ketone, methyl isobutyl ketone, acetone, methylamine ketone, cyclohexanone, isophorone, diacetone alcohol, etc. Typical examples include ketone solvents. Particularly, the ketone solvent contributes to improving the leafing properties of the aluminum pigment, so it is preferable to include the ketone solvent in a part of the solvent. Each of these components usually contains 5 to 5 parts of leafing type aluminum pigment per 100 parts by weight of epoxy resin.
100 parts by weight, 200 parts by weight or less of a solvent, 200 parts by weight or less of a rust preventive pigment and an extender pigment, and a hardening agent of 0.5 parts per 1.0 epoxy equivalent of the epoxy resin.
It is used in an amount of about 1.0 equivalent. Further, it is appropriate to use scaly mica in an amount of about 1 to 40% by weight in the paint. If the amount of scaly mica used is less than the above range, the leafing properties of the aluminum pigment cannot be improved, and if it is too large, water resistance, adhesion, etc. will deteriorate, which is not appropriate. Furthermore, in the present invention, the leafing property of the aluminum pigment is improved even if a part of the scale-like mica is replaced with α-crystal aluminum oxide having a particle size of about 1 to 10 μm. The coating composition of the present invention is used in the form of a three-component type consisting of a base component mainly composed of epoxy resin, a curing agent component, and an aluminum paste component, and a two-component type in which the aluminum paste component is mixed into the base component in advance. be done. Note that when a ketone solvent is used as a solvent, it should be mixed into the curing agent component since it reacts with the aluminum pigment. As mentioned above, the coating film obtained by the aluminum pigment-containing epoxy resin coating composition of the present invention has good leafing properties, so the coating film has a good appearance and is excellent in weather resistance and rust prevention properties. In particular, epoxy resins that use bisphenol F type epoxy resins and aromatic polyamines as hardeners can be coated on a wide range of metal substrates, and do not require a top coat; It can also be used as a top coat, making it possible to shorten the painting process. The present invention will be explained in detail below with reference to Examples. In the examples, "parts" and "%" are expressed on a weight basis. Example 1 Bisphenol F type epoxy resin (Epicron
830: Dainippon Ink Chemical Industry Co., Ltd.) 30 parts, stearic acid coating aluminum paste (Aluminum Paste 53-119: Toyo Aluminum Co., Ltd.) 15
1 part, 3 parts of xylene, and 2 parts of ethyl cellosolve were stirred and mixed to form a main ingredient. Separately, 20 parts of scaly mica (major diameter 5 to 20μ), 15 parts of aromatic polyamine (diaminodiphenylmethane derivative) (active hydrogen equivalent 120), 10 parts of xylene, and 5 parts of methyl isobutyl ketone were stirred and mixed, and a curing agent was added. as an ingredient. A paint containing a mixture of the main component and the curing agent component in a ratio of (1:1) is applied with a brush to a dry film thickness of 100μ on a steel plate (rust prevention treatment level SiS-St2).
It was left to air dry for one week. Example 2 A paint was prepared and coated in the same manner as in Example 1, except that a metaphenylene diamine derivative (active hydrogen equivalent: 120) was used as the aromatic polyamine. Example 3 A paint was prepared and painted in the same manner as in Example 1, except that a xylene diamine derivative (active hydrogen equivalent: 100) was used as the aromatic polyamine. Example 4 In Example 1, 10 out of 20 parts of limpenic mica
A paint was prepared in the same manner as in Example 1, except that part was replaced with α-crystalline aluminum oxide having a particle size of 3 to 4μ,
Painted. Example 5 A paint was prepared and painted in the same manner as in Example 1, except that bisphenol A type epoxy resin (Epicote 828: manufactured by Ciel Chemical Co., Ltd.) was used as the epoxy resin. Comparative Example 1 A paint was prepared and painted in the same manner as in Example 5, except that talc was used instead of flaky mica powder. Comparative Example 2 A paint was prepared and coated in the same manner as in Example 1, except that scaly mica (long axis 50 to 100 μm) was used instead of scaly mica (long axis 5 to 20 μm). Comparative Example 3 Example 1 except that mica powder (average particle size 0.7μ) was used instead of flaky mica (major axis 5 to 20μ).
A paint was prepared and applied in the same manner. Leafing properties (visual judgment), yellowing (visual judgment after 3 months of outdoor exposure), and water resistance (after immersion in tap water for 1 month) of the coating films obtained from Examples 1 to 5 and Comparative Examples 1 to 3 The results are shown in Table 1. As is clear from Table 1, the paints of the present invention (Examples 1 to 5) had excellent paint film appearance and water resistance, but the paints using talc instead of flaky mica (Comparative Example 1) ) and paints using flaky mica with particle sizes that were too large or too small (Comparative Examples 2 and 3), the leafing properties of the aluminum pigment were poor and yellowing was also observed. 【table】

Claims (1)

[Scope of Claims] 1. A leafing type aluminum pigment-containing epoxy resin coating composition having a major axis of about 1 to
An aluminum pigment-containing epoxy resin coating composition characterized by containing 20μ of flaky mica. 2. The aluminum pigment-containing epoxy resin coating composition according to claim 1, wherein the epoxy resin is a bisphenol F type epoxy resin and the curing agent is an aromatic polyamine. 3. The aluminum pigment-containing epoxy resin coating composition according to claim 1 or 2, which contains 1 to 40% by weight of scaly mica.