JPH05293439A - Method for applying polyphenylene sulfide resin powder paint containing fluoroplastic - Google Patents

Abstract

(57) [Summary] [Object] To provide a coating method using a polyphenylene sulfide resin-based powder coating material containing a fluororesin to obtain a uniform and continuous coating film free from wetting defects. [Structure] On the surface of a base material, a polyphenylene sulfide resin-based powder coating material is used as a primer for undercoating, and then a polyphenylene sulfide resin-based powder coating material containing a fluororesin is overcoated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for coating a polyphenylene sulfide resin-based powder coating material containing a fluororesin, which can form a uniform and continuous coating film.

[0002]

2. Description of the Related Art Polyphenylene sulfide has heat resistance,
It has excellent properties such as water resistance, chemical resistance, abrasion resistance, and electrical insulation. For this reason, paints using this as a base resin are used in fields such as metal rust prevention, corrosion prevention, and electrical insulation treatment.

Fluorine resin has heat resistance, non-adhesiveness,
Excellent properties such as slidability, water resistance, chemical resistance, electrical insulation, and weather resistance. For this reason, paints using this as a base resin are used for the purpose of imparting non-adhesiveness, slidability, corrosion resistance, chemical resistance, weather resistance and the like to metals.

However, the polyphenylene sulfide resin has the drawbacks that it does not have the characteristics such as non-adhesiveness and slidability unlike the fluororesin, and the weather resistance is not very good. On the other hand, the fluororesin has drawbacks that it is inferior in abrasion resistance and expensive.

Therefore, at present, the polyphenylene sulfide resin-based coating material and the fluororesin-based coating material are used properly according to the use and purpose.

[0006]

It is expected that if a coating material containing both a polyphenylene sulfide resin and a fluororesin is used for coating, a coating film can be obtained which makes the best use of both of them and complements each other's shortcomings. It In fact, such a composition is disclosed in, for example, JP-A-50-48038.

However, when a polyphenylene sulfide resin-based powder coating material containing a fluororesin is applied to a substrate such as a metal, a portion where the coating material is not locally adhered to the coating film after baking (hereinafter referred to as "wetting defect"). There is a large tendency to occur. This is because the affinity between the fluororesin contained in the coating composition and the base material such as metal is poor.

An object of the present invention is to provide a coating method using a polyphenylene sulfide resin-based powder coating material containing a fluororesin to obtain a uniform and continuous coating film free from wetting defects.

[0009]

[Means and Actions for Solving the Problems] A method for coating a polyphenylene sulfide resin-based powder coating material containing a fluororesin of the present invention comprises the steps of: ,
It is characterized in that a polyphenylene sulfide resin-based powder coating material containing a fluororesin is overcoated.

First, in the method of the present invention, the polyphenylene sulfide resin used in the powder coating for undercoating and topcoating is

[Chemical 1] Is a polymer having a repeating unit of, and most of the terminal ends of the molecular structure are -SNa. Such a polyphenylene sulfide resin is disclosed, for example, in Japanese Examined Patent Publication No. 45-336.
It is manufactured by the method described in Japanese Patent Publication No. 8 or Japanese Patent Publication No. 52-12240.

Further, a polyphenylene sulfide resin in which the terminal SNa group is converted to an SH group, or another polyphenylene sulfide resin can also be preferably used.

The powder of the polyphenylene sulfide resin used in the present invention has a maximum particle size of 200 μm so that it is suitable for powder coating such as electrostatic powder coating, fluidized-bed coating, and thermal spraying.
Hereafter, it is more preferably 150 μm or less, and the average particle size is preferably 30 to 80 μm.

In the method of the present invention, the fluororesin powder used in the powder coating for topcoating is not particularly limited. For example, PTFE (tetrafluoroethylene polymer), PFA
Used for powder coating such as (tetrafluoroethylene / perfluorovinyl ether copolymer), FEP (tetrafluoroethylene / hexafluoropropylene copolymer), ETFE (tetrafluoroethylene / ethylene copolymer) Any of the known fluororesin powders can be preferably used.

The fluororesin powder used in the present invention is
Maximum particle size of 200μm or less, suitable for powder coating
More preferably, it is 150 μm or less, and the average particle size is 1 to
It is preferably 80 μm.

The amount of the fluororesin powder added is 3 to 100 parts by weight of the polyphenylene sulfide resin powder.
It is preferably 30 parts by weight. When the addition amount is less than 3 parts by weight, the effect of adding the fluororesin can hardly be expected. If the addition amount is more than 30 parts by weight, the smoothness of the coating film is significantly impaired, which is not preferable. A more preferable addition amount is 5 to 20 parts by weight with respect to 100 parts by weight of the powder of the polyphenylene sulfide resin.

The powder coating for undercoating and topcoating used in the method of the present invention has a surface hydrophobized with a silylating agent for the purpose of preventing cissing phenomenon occurring on the surface of the coating film.
It is preferable to add 0.05 to 0.6% by weight of ultrafine hydrophobic silica having an average primary particle diameter of 0.1 μm or less.

When a coating film having particularly excellent smoothness is required, in addition to the hydrophobic silica, the average particle diameter of the primary particles of the powder coating material for the undercoat and topcoat used in the method of the present invention is 0.1. 1 μm or less, more preferably 0.005
It is preferable to add 0.05 μm of ultrafine aluminum oxide.

The amount of ultrafine aluminum oxide added together with the hydrophobic silica is preferably in the range of (weight of aluminum oxide) / (weight of hydrophobic silica) ≦ 2.0.

In the powder coating for undercoating and topcoating used in the method of the present invention, if necessary, other additives such as coloring pigments such as titanium dioxide, rouge (iron oxide) and carbon black; An appropriate amount of an inorganic filler such as glass beads, glass powder, glass short fibers, glass flakes, talc, calcium carbonate, barium sulfate; a UV stabilizer; an anticorrosive agent may be added. Further, other polymers such as polyamide, polycarbonate, polysulfone, polyether sulfone, polyphenylene oxide, polyimide, polyamideimide, and epoxy resin may be added.

The composition of the present invention comprises the above components.
For example, it can be easily manufactured by uniformly mixing with a stirring device such as a Henschel mixer.

[0021]

EXAMPLES The present invention will be described in more detail based on the following examples.

Each component was blended in the composition shown in Table 1 (Table 1
Was sufficiently mixed with a Henschel mixer to prepare a polyphenylene sulfide resin-based powder coating composition A and a polyphenylene sulfide resin-based powder coating composition B containing a fluororesin.

[0023]

[Table 1] The details of each component in the table are as follows.

Polyphenylene sulfide powder: manufactured by Topren Co., Ltd., trade name Topren T-1.

Fluororesin powder: manufactured by Kitamura Co., Ltd., trade name KTL-610 (PTFE), average particle size 10 μm.

Hydrophobic silica fine powder: manufactured by Nippon Aerosil Co., Ltd., trade name Aerosil R-974, average particle diameter of primary particles is 12 mμ.

Aluminum oxide fine powder: aluminum oxide C, trade name, manufactured by Degussa, having an average primary particle size of 13 mμ.

Short glass fiber: manufactured by Nippon Sheet Glass Co., Ltd., trade name Microglass Surfaceland REV9, fiber diameter 13 ± 1.5 μm, fiber length 35 ± 15 μm, average aspect ratio 2.7.

Example 1 A rectangular copper wire having a thickness of 2 mm, a width of 6 mm and a length of 80 cm was pickled and further washed with water. 40μ of polyphenylene sulfide resin powder coating composition A as a primer on the surface
m was coated with electrostatic powder, baked at a temperature of 350 ° C. for 20 minutes, and then left to cool. On this primer coating film, a polyphenylene sulfide resin-based powder coating composition B containing a fluororesin was electrostatically powder-coated to a film thickness of 50 μm.
After baking for 40 minutes at a temperature of 0 ° C., it was allowed to cool. The resulting coating film was uniform, smooth and continuous without wetting and cissing.

Example 2 A polyphenylene sulfide resin powder coating composition containing a polyphenylene sulfide resin powder coating composition A as a primer and electrostatic powder coating having a film thickness of 40 μm, and immediately containing a fluororesin without baking. A coating film was formed in the same manner as in Example 1 except that B was electrostatically powder coated to a film thickness of 50 μm. The obtained coating film was uniform and smooth without causing wetting defects and repelling as in the case of Example 1.

COMPARATIVE EXAMPLE A polyphenylene sulfide resin powder coating composition B containing a fluororesin was electrostatically powder coated to a film thickness of 90 μm on the surface of a rectangular copper wire which had been pickled and washed in the same manner as in Example. Three
After baking at a temperature of 50 ° C. for 40 minutes, it was allowed to cool. The resulting coating film was discontinuous with several wetting defects.

[0032]

As is apparent from the above description, the coating method of the present invention can form a coating film of a polyphenylene sulfide resin containing a uniform and continuous fluororesin without wetting defects. This coating film has the excellent characteristics that both the polyphenylene sulfide resin and the fluororesin have. Therefore, especially pre-coated boards, electric / electronic parts, electric wires, automobile parts, chemical plants, hot water pipes, hot spring pipes, ships / seawater plants, oilfield pipes,
It can be effectively applied to heat exchangers, electrical appliances, machine parts, food trays, etc.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location C09D 181/02 PML 7167-4J

Claims (1)

[Claims] 1. A polyphenylene containing a fluororesin, which comprises undercoating a polyphenylene sulfide resin-based powder coating as a primer on the surface of a base material and then overcoating a polyphenylene sulfide resin-based powder coating containing a fluororesin. Coating method of sulfide resin powder paint.