JPS5822267B2 - Aluminum Oshidashi Zaino Funtaite Souhou - Google Patents

Description

[Detailed description of the invention] The present invention relates to powder coating methods.

More specifically, the present invention relates to a powder coating method for aluminum extrusions, such as extrusions made of non-heat-treated aluminum alloys used for interior decoration materials, pipes, and the like.

Traditionally, aluminum extrusions have been painted to be used, for example, as decorative materials, by anodizing them and then applying electrodeposition coating or powder coating, but the process is extremely complicated. Ta.

In addition, in order to shorten the process, a powder coating method has been proposed that consists of a step of extruding the extruded material, followed by a step of cooling the extruded material to 150 to 350°C, and a painting step of spraying powder coating onto the cooled extruded material. Although this method has been proposed (see Japanese Patent Application Laid-open No. 49-55729), it is not sufficient because it is complicated and requires cooling to be divided into two stages.

The present inventor has developed a coating method for extruded materials using non-heat-treated aluminum alloys, which utilizes the temperature during extrusion to the maximum extent possible, and
We have discovered a coating method that allows powder coating to be applied immediately without cooling, and have arrived at the method of the present invention.

That is, the present invention involves powder coating an extruded material that is continuously extruded following an extrusion process of extrusion molding an aluminum non-heat treatable alloy at 350 to 420°C using a resin powder consisting essentially of polyethylene terephthalate. This is a powder coating method for aluminum extrusions, which is characterized by cooling the aluminum extrusions.

The resin powder substantially consisting of polyethylene terephthalate used in the present invention refers to one whose resin property is substantially polyethylene terephthalate, and also includes copolymers or blends containing a small amount of a copolymer component, for example, about 30 molar proportions. include.

In particular, resins containing neopentyl glycol as a copolymerization component are preferred.

The resin powder is usually 150μ or less, preferably 40 to 150μ
It is preferable to use particles having a degree of polymerization such that the resulting coating film has good appearance and properties, i.e., an intrinsic viscosity of 0.45 or more when measured at 35°C using 0-chlorophenol as a solvent. use something

This powder is processed by known methods such as cryo-pulverization and crystallization.
...It can be obtained by pulverizing with a complete crusher or by crushing with an impact crusher.

These powders contain commonly used additives such as dyes and pigments,
There is no problem even if additives such as stabilizers, UV absorbers, thixotropic agents, matting agents, fillers, metal powders, and antistatic agents are included or mixed into the powder.

The aluminum non-heat treatment alloy used in the present invention is JIS
It is an alloy with numbers of 1000, 3000, 4000° and 5000.

When coating these extruded materials, the extruded materials extruded at, for example, 400°C are introduced as they are into, for example, an electrostatic powder coating zone or a fluidized dip coating zone, the powder is adhered and melted, and then immediately guided to a cooling zone. Forms a coating film on the surface.

When using the resin of the present invention, the temperature of the extruded material is 350°C
~420°C is required.

If the temperature of the extruded material is 350° C. or lower, the powder will not completely melt, resulting in a coating film with poor surface condition.

In this case, the surface condition is not improved although it is melted by post-heating.

Moreover, if the temperature exceeds 420°C, air bubbles will be drawn into the coating film, which is not preferable.

After the powder adhering to the surface of the extruded material is melted, it is necessary to cool the extruded material with a fluid such as water.

If natural cooling is performed without forced cooling, properties such as surface hardness of the coating film will improve, but adhesion will decrease, so this is not preferred. When the method of the present invention is used, the temperature of extrusion molding can be fully utilized, and The substrate is cooled by the heat from the melting of the powder, making it an optimal process for effective use of heat.

Furthermore, the resin of the present invention has very good adhesion to aluminum and does not require primer treatment.

The present invention will be described in detail below with reference to Examples.

Example J I 8 No. 1100 aluminum alloy is extruded at 400°C.

The extruded material that is continuously extruded is immediately processed into a resin powder ([η]-0
, 50,100 mesh passing through 100%, 150 mesh passing through 30 sections) was introduced into the fluidized immersion bed and brought into contact for 1 second to perform powder coating.

After the extruded material leaves the fluidized immersion bed and the adhering powder is melted (for about 2 seconds), it is led to a cooling zone and cooled.

The extruded material thus obtained had a coating film with a thickness of 100 μm uniformly adhered thereto, and the pencil hardness was H without peeling in the goban tape test.

A 90° bending test was performed, but no abnormality was found. Note that when this extruded material was heat treated at 140° C. for 5 minutes, the surface hardness was 3H.

Claims (1)

[Claims] 1. The extruded material that is continuously extruded following the extrusion process of extrusion molding an aluminum non-heat treatment alloy is powder coated at 350 to 420°C using a resin powder consisting essentially of polyethylene terephthalate, and then cooled. A powder coating method for aluminum extrusions characterized by: