JPS61193842A - Two-coat two-baking precoated board having excellent heat-resistant property - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a two-coat, two-bake precoated board with excellent heat resistance.

[Conventional technology and its problems]

Continuous painting line for Al plate or AA plated steel plate! ! 1
The so-called pre-coated board is known for its excellent corrosion resistance and weather resistance, and it also comes in a wide variety of colors, so it is currently widely used for exterior building materials (roofs, etc.) and home appliances. When this pre-coated board is used for the above purposes, it undergoes processing such as press working, so there has been a tendency to place emphasis on its workability, and for this reason, the paint used for it has overwhelmingly been epoxy resin for the base coat, and for the top coat. Acrylic, polyester, vinyl chloride plastisol, vinyl 27ts, silicone polyester resin, etc. are used for this.

By the way, the heat resistance of these coating films is expressed by the Tg (glass transition temperature) of the primarily cured coating film, and at temperatures above Tg, the mechanical properties of the coating film decrease significantly, and
Gas against paint film.

Water permeability increases significantly. The Tg point of the coating film for painted steel sheets currently used is as follows.

However, in reality, painted boards are often used in environments where the Tg point is temporarily exceeded.For example, the Tg point of acrylic and polyester coatings used on roofs is 50 at maximum.
The temperature is ~60℃, but on a roof in midsummer it can reach 8℃ due to direct sunlight.
In some cases, the temperature may exceed 0°C. Exposure of a paint film during use to a relatively high temperature environment, even for a short period of time, is considered to be one of the major factors that accelerates the deterioration of the paint film. It has been observed that when coatings such as vinyl chloride plastisol are exposed to high temperatures of 80° C. or higher for a long period of time, hydrochloric acid is generated and the coating deteriorates, and the underlying metal is corroded and the coating peels off. The most heat-resistant paint film currently used on painted plates is one made of a mixture of vinyl 27thide resin and acrylic resin, but its continuous heat resistance temperature is only 120 to 130°C.

Heat-resistant resins such as polyimide are known as resins with excellent heat resistance, but coating films made of these resins have poor workability due to their lack of flexibility, and are difficult to apply to pre-coated boards that are intended for processing such as press working. Not commonly used.

[Means to solve the problem]

In view of such conventional problems, the present invention aims to provide a two-coat, two-bake plate that has a heat resistance of 200° C. or more and has excellent corrosion resistance and workability. Yes.

Therefore, in the present invention, a primer coating film is formed on the surface of an Al plate or an Al-plated steel plate, the main heat-resistant resin being polyphenylene sulfide resin, polyether sulfon resin, or a mixture of polyphenylene sulfide resin and polyether sulfon resin. The basic principle is that a coating film containing polyphenylene sulfide resin, polyether sulfone resin, tetra7tethylene resin, St-modified polyester resin, or a mixture of two or more of these resins is formed thereon. Characteristics.

The present invention will be explained in detail below.

The present invention relates to a 2-coat, 2-bake precoated plate, and the raw metal plate thereof is an Al plate or a U-plated steel plate. These material plates have high heat resistance and excellent corrosion resistance.

On the surface of the material board as described above, a coating film is formed using polyphenylene sulfide resin (PPS), polyether sulfone resin (PES), or a mixture of both resins (PPS + PE5) as the main thermoplastic resin as a primer. Ru. This primer coating has a high temperature (over 200℃)
It has heat resistance for regular use.

Further, it is preferable that the primer coating film contains a rust preventive pigment in order to place emphasis on corrosion resistance. As this anti-corrosion pigment, conventionally used inorganic pigments such as strontium-based pigments, Al-10 inorganic pigments, etc. are used.

The following types of paints can be cited as examples of primers used in the present invention.

(a) Solvent: 60-70% (NMP + Tsurpets)
Heat-resistant resin = 20-30% (PES) Rust-preventing pigment nystrontium chromate - x% of pus and fat content) (b
) Solvent 2 65% (NMP+Nurubetsu) Heat resistant resin = 2
0 to 30 (PKS) Rust-preventing pigment, Al, and inorganic pigment (or borate pigment) Such a primer is subjected to a baking treatment after the coating film is formed. This baking temperature is lower than the baking temperature after topcoating.
Generally, it is carried out at a temperature range of 200 to 400°C.

A top coat (finish) coat is formed on the primer coat.

This coating film uses polyphenylene sulfide resin (pps) and polyether sulfon resin (PE) as heat-resistant resins.
S), tetrafluoroethylene resin (PTFE), or S
The main component is a modified polyester resin or a mixture of two or more of these resins. Among the above coating films, a coating film containing PTFE, that is, a coating film mainly composed of PTFE alone or a combination of PTFE and other heat-resistant resins. Mixtures (e.g. PTFE + PES, PTFE +
The coating film whose main component is PPS etc.

In addition to being heat resistant for general use at high temperatures (200°C or higher), it also has processing lubricity and excellent press formability as a characteristic of tetrafluoroethylene resin, making it suitable as a finishing coating for press processing. ing. Furthermore, coating films containing tetrafluoroethylene resin have excellent non-adhesive properties (mold releasability).

In addition, the finishing coating film may be one whose main component is PES, PPS, or PES + PPS, similar to the primer coating described above, or one whose main component is Sl-modified polyester resin or a mixture of this and other heat-resistant resins. There are some that do. The above Si-modified polyester has Si: 40
It has heat resistance of about 250°C.

In addition, if a rust preventive pigment is included in the finished coating film, it tends to impair the processing lubricity and non-adhesiveness of the coating film, so if these properties are important, avoid including the rust preventive pigment. is preferred. However, a pigment for luster (for example, AA) may be included.

After the coating film is formed, the steel plate is subjected to a second baking process in a heating furnace. This baking temperature is about 350 to 400°C.

〔Example〕

Pre-coated plates of the present invention material and comparative material were produced by forming a two-coat, two-coat coating film as shown in Table 1 on an Al plate,
We compared their paint adhesion, heat resistance, and processing lubricity. These results are also shown in Table 1.

The test conditions for each characteristic test are as follows.

0 processing lubricity test die: 40.9j21-3R, Ponche 40 Goo 4
R.

Wrinkle holding plate: In a deep drawing test using 40.5ρ, the wrinkle holding pressure was increased and the limit wrinkle holding pressure was measured.
By end + tape peeling ◎: No peeling O: Point peeling Δ: Peeling about 10 inches ×: Peeling about 20% 0 Adhesion test after painting OT By bend + tape peeling [Effect of the invention] According to the softwood invention described above, high temperature It has the usual heat resistance below, as well as excellent press formability, as well as corrosion resistance and paint adhesion, making it extremely useful as a copper plate for corrosion-resistant and heat-resistant coated products manufactured by press processing. be able to.

Claims (1)

[Scope of Claims] A primer whose main heat-resistant resin is polyphenylene sulfide resin, polyether sulfon resin, or a mixture of polyphenylene sulfide resin and polyether sulfon resin, applied to the surface of an Al plate or Al-plated steel plate. A coating film is formed, and a coating film containing polyphenylene sulfide resin, polyether sulfone resin, tetrafluoroethylene resin, Si-modified polyester resin, or a mixture of two or more of these resins as a main component is further applied thereon. A 2-coat, 2-bake pre-coated board with excellent heat resistance.