JPS6191270A - Formation of coating film - Google Patents

Abstract

PURPOSE:To form a coating film having excellent flexibility, heat resistance, hardness, etc., by applying a composition which contains a polybutadiene resin having (meth)acryloyl groups, a phosphate compound, etc., and curing it by irradiation with radiation. CONSTITUTION:A polybutadiene resin having terminal functional groups comprising (meth)acryloyl groups, a reactive diluent comprising a low-viscosity compound having functional groups such as (meth)acryloyl groups in the molecule (e.g., tetrahydrofurfuryl acrylate), and a phosphate compound having (meth) acryloyl groups (e.g., acryloyloxyethyl phosphate) are mixed to prepare a coating composition. This coating composition is applied on the surface of a base material to be coated, such as a metal sheet and is cured by irradiation with radiation, such as electron beams, to form an objective coating film.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for forming a coating film having excellent flexibility, heat resistance, and surface hardness.

[Prior art]; In coating films for thin metal plates, surfaces of flexible printing/wiring boards, surface insulation coatings, etc., coating film properties such as - excellent flexibility, heat resistance, and surface hardness are used. is necessary.

The method of forming these coatings is to apply a thermosetting paint made of liquid resin such as epoxy or urethane and heat cure it.According to this method, It has good adhesion to the coating substrate.
Although it is possible to form coating films with excellent coating properties such as flexibility, heat resistance, and surface hardness, it is difficult to rationalize the manufacturing process because it takes time to cure the coating film. Disadvantages: 0' Recently, in forming these coating films, coatings made of radiation-curable resins have been applied and coating films have been continuously formed by radiation curing. Which method allows the coating film to be cured quickly, which can help streamline the manufacturing process. ,
[Problems to be solved by the invention]) In the conventional technology, when a coating film is not formed with a radiation-curable resin, it is extremely difficult to provide a coating film with the following characteristics: flexibility, heat resistance, and surface hardness. It was difficult for 1J. □In other words, if you increase the heat resistance or surface hardness, you will only get a hard and brittle coating that will break as soon as you bend it.If you increase the heat resistance or surface hardness, you will get a hard and brittle coating that will break easily when you bend it. Only a coating film with poor surface hardness was obtained.

In the process of conducting various studies on radiation-curable coatings tζ, the present inventors have learned that it is extremely difficult to satisfy flexibility, heat resistance, and surface hardness all at the same time.

[Means for solving problems]

In order to solve the above-mentioned problems, the present inventors have continued to work diligently to develop a method for forming a coating film that has excellent flexibility and also satisfies heat resistance and surface hardness. I proceeded with my research.

As a result, among the many radiation-reactive compounds,
In particular, if a coating composition containing as all components a polybutadiene resin having a functional group of an acryloyl group or a methacryloyl group, a reactive diluent, and a phosphoric acid ester compound having an acryloyl group or a methacryloyl group is used, excellent flexibility can be achieved. This phenomenon is notable for the fact that it is possible to form a coating film that has both excellent heat resistance and surface hardness. In particular, it is said that the hardness of the coating film is significantly improved by adding a phosphoric acid compound having an acryloyl or methacryloyl group to a paint paste consisting of a polybutadiene resin having a functional group of an acryloyl or methacryloyl group and a reactive diluent. Thoughts 1. ＞It was found that all the cases exhibited severe V1 behavior.

The present invention has been made based on the above findings, and its gist is that the surface of the substrate to be coated contains an acryloyl group or a methacryloyl group. A coating composition containing as all components a polybutadiene resin having F, tsk, a reactive diluent, and a phosphoric acid ester compound having all acryloyl groups or methacryloyl groups is applied, and then the coating film is cured by full irradiation with radiation. There is a method for forming a coating film.

The polybutadiene resin which is completely blind to functional groups such as acryloyl or methacryloyl groups as used in the present invention is a polybutadiene prebolimer having an average molecular weight of 2,000 to 4,000 and which is completely blind to functional groups such as acryloyl or methacryloyl groups at the end of the molecule. The acryloyl group or methacryloyl group is bonded to the end of polybutadiene by an esterification reaction between the 10H group at the end of the polybutadiene main chain and an acid having an acryloyl group or methacryloyl group.

In addition, the reactive diluent referred to in the present invention refers to t-1 or 2 functional groups such as 5 acryloyl groups and methacryloyl groups in the molecule.
It is a low viscosity compound with a

The composition ratio of the polybutadiene resin and the reactive diluent is preferably within the range of 90:10 to 50:50 from the viewpoint of the flexibility and heat resistance of the coating film.

The phosphoric acid ester compound having an acryloyl group or a methacryloyl group referred to in the present invention is an ester compound of a compound having an acryloyl group or a methacryloyl group and phosphoric acid, such as 2-methacryloyloxyethyl phosphate or 2-acryloyloxy There are compounds such as ethyl phosphate.

The amount of the phosphoric acid ester compound having an acryloyl group or methacryloinosyl group added is 0.3 part by weight or more based on 100 parts by weight of the total amount of the polybutadiene resin and the reactive diluent. If the amount added is less than 0.3 parts by weight, the surface hardness of the coating film will be poor. Furthermore, if the amount added is too large, heat resistance tends to decrease. , particularly preferably 0.
It is in the range of 5 to 3 parts by weight.

The coating composition according to the present invention may optionally contain a polymerization initiator, a colorant such as a pigment or dye, a surface treatment agent such as an alkyl titanate or a silane coupling agent, a viscosity modifier such as ultrafine silica, a silicone compound, etc. leveling agent,
All auxiliary materials such as organic and inorganic fillers may be added. The coating composition according to the invention is prepared by kneading with a conventional stirrer or roll.

Methods for applying this paint onto the surface of the substrate to be coated include brush coating, roller coating, flow coating, and a method called a silk screen method.

In the present invention, after the coating composition is applied to the surface of the substrate to be coated, it is fully irradiated with radiation to be cured. As the radiation, electron beams or ultraviolet rays can be used. The irradiation dose of the electron beam may be 0.5 to 30 Megaland. In ultraviolet irradiation, compounds such as phenylketone compounds, xanthones, suberones, amino compounds, and azo compounds are used as polymerization initiators. Among these compounds,
The coating film properties using suberones, xanthones, and phenylketone compounds were better. Irradiation with ultraviolet light is preferably carried out for about 5 to 60 seconds using one to several ultraviolet lamps of 1 to 10 Wi.

Incidentally, after the coating film is irradiated with radiation and cured, the coating film can be heat-treated to further improve the coating film characteristics.

〔Example〕

Example 1 Polybutadiene: x Polybd A-8025 (acrylic modified polybutadiene resin, trade name manufactured by ARCO Chemical Co., Ltd.)...80 parts by weight Tetrahydrofurfuryl acrylate (reactive diluent)...20 parts by weight 2-acryloyl Roxyethyl phosphate...
lfi part benzyl dimethyl ketal (polymerization initiator)
...5 parts by weight Phthalocyanine Green (coloring agent) ...1 part by weight Erological (ultrafine silica) ...5 parts by weight Silicone leveling agent
... A coating composition was prepared by kneading 1 part by weight using three rolls.

This coating composition was applied to the surface of a copper foil to a thickness of 20 μm by a total silk screen method. This was cured by irradiating one line of ultraviolet light with 577"t" of UV light for 30 seconds.

As a result of bending the thus obtained coated copper foil sheet by 180 degrees with the coated surface completely outside or inside, the coated film was not damaged and had sufficient flexibility and adhesion. Furthermore, in order to investigate the heat resistance of this product, a solder resistance test was conducted by immersing it in a 260° C. solder bath for 10 seconds. As a result, no abnormality occurred in the coating film even when immersed in solder, and it was confirmed that the coating film had excellent heat resistance. Furthermore, when the surface hardness of this coating film was examined using a pencil hardness, it was confirmed that it had a hardness of 6H or more.

Example 2 In Example 1, benzyl dimethyl ketal was removed from the paint composition, and the paint was prepared and applied in the same manner as in Example 1, and was cured by irradiating with 10 megarads of electron beam instead of ultraviolet rays. Ta. As a result of examining the properties, it was confirmed that the properties were comparable to those of Example 1.

Comparative Example 1 In Example 1, a coated copper foil sheet was prepared under the same conditions as in Example 1, except that 2-acryloyloxyethyl phosphate was not added.

However, the pencil hardness is low at H.

Example 3 In Example 1, a coating film-forming copper foil sheet was prepared under the same conditions as in Example 1, except that the blending ratios of the polybutadiene resin, the reactive diluent, and the phosphoric acid compound were changed. Characteristic? The results were as shown in Table 1.

Table 1 Comparative Example 2 A coating film-forming copper foil sheet was created under the same conditions as in Example 1 except that the blending amounts of the polybutadiene resin, reactive diluent, and phosphoric acid compound were changed. . The characteristics were as shown in Table 2.

Table 2 [Effects of the Invention] According to the present invention, a coating film with extremely excellent flexibility, heat resistance, and surface hardness can be easily formed using a radiation-cured coating material.

Claims (1)

[Claims] (1) A coating composition containing as components a polybutadiene resin having a functional group of an acryloyl group or a methacryloyl group, a reactive diluent, and a phosphoric acid ester compound having an acryloyl group or a methacryloyl group is applied to the surface of the substrate to be coated. A method for forming a coating film, which comprises: then curing the coating film by irradiating with radiation.