JPS5910888B2 - Manufacturing method for matte processing molds for synthetic resin molded products - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mold that can satisfactorily matt the surface of a synthetic resin molded product.

There are various methods of matting a thermoplastic resin molded article, but generally it is carried out using a mold that has been subjected to matting.

Methods for matting metal include (1)-15 etching using chemical chemicals (acids and alkalis); (2
) A method of physically roughening the surface by sandblasting.
(3) A method of performing matte plating. Alternatively, there is a method of using these together. The purpose of matting a thermoplastic resin molded product is generally to give the molded product a soft feel by diffusely reflecting light rays. However, since the matting effect of the above method is small when used alone, it is necessary to use them in combination, which has the disadvantage of complicating the process of producing a matting mold. Furthermore, with these methods, it is extremely difficult to obtain a mold with a desired roughness. Therefore, the inventors of the present invention have conducted intensive studies on matting means for molds for thermoplastic resin molded products, and have found that adding even smaller irregularities to the irregularities of a certain roughness itself is effective in matting the molded product. This discovery led to the present invention.

The present invention can be achieved by thermal spraying the mold surface.

Thermal spraying coats materials such as metals and ceramics with oxygen-acetylene (
Or hydrogen) is melted and sprayed from a nozzle using a flame to coat the target substrate (usually metal). If a matte processing mold is made by thermal spraying, it is not only easy to obtain a very rough surface, but also it is possible to create a complex shape in which microscopically existing unevenness itself has even smaller unevenness. Porous surfaces can be created. When this thermal sprayed mold was used, it became possible to obtain a thermoplastic resin molded product with an extremely matte effect. Using a mold whose surface has become complex and porous due to thermal spray processing has a great matting effect, as it not only allows the rough unevenness to be faithfully formed on the surface of the molded product, but also the microscopic unevenness. This is thought to be because it can be attached.

That is, the molten thermoplastic resin is introduced into a mold and is shaped by the rough irregularities on the mold surface, but when it shrinks by cooling, it is shaped by the microscopic irregularities of the mold. Therefore, it is thought that the semi-molten molded product is subjected to shearing and the surface of the molded product is subjected to an action similar to being scratched, which increases the matting effect. Therefore, if the mold is simply provided with rough irregularities, the matting effect will be very small, and it is important to have a porous surface with a complex shape like this thermal spray mold. 95
We then experimentally confirmed what level of roughness the surface of the matte mold should have in terms of the matte effect.

In this experiment, commercially available sandpaper was layered on a thermoplastic resin sheet, which was then sandwiched between two mirrored plates, hot pressed, and after cooling, the sandpaper was peeled off to create a matte finish on the sheet surface. be. From this experiment,
It has been found that the stripping effect varies considerably depending on the roughness of the sandpaper, and that sandpaper equivalent to #600 is good. #6
As the sandpaper becomes rougher than #00, the matting effect becomes smaller, and below #60, the resin adheres to the sandpaper and it is impossible to peel it off. Similarly, the matte effect became smaller as the particles became finer than #600. In the present invention, a rough matte processing mold with a large matte effect is produced by spraying, and its effect is significantly greater than that of other matte molds. Another advantage of the matting means by spraying a mold according to the present invention is that it is easier to obtain a desired roughness than other matting means. The mold according to the present invention is used for injection molding, compression molding, blow molding, vacuum or pressure molding, and the like. EXAMPLES In order to further clarify the effects of the present invention, Examples will be described. Example
1. A molybdenum/nickel/aluminum mixed powder material (#447 manufactured by Daiichi Metco Co., Ltd.) is melted in an oxygen-acetylene gas flame and sprayed from a nozzle onto the surface of an injection mold to obtain a flat plate-shaped molded product to give it a matte finish. I did this.

The surface roughness was equivalent to #600 commercially available sandpaper. This matted mold was set in an injection molding machine, and polypropylene (MFR melt flow ratio: 1.0) was injected at a resin temperature of 250° C. and an injection pressure of 80 kg/CrA. Table 1 shows the matte state of this injection molded product.
Reference Example 1 A molded product manufactured using the same materials and under the same conditions as Example 1, except that a mold with the same shape as Example 1 was subjected to #150 sandblasting, etched, and then matt plating was used. Table 1 shows the matte state.

The roughness of the mold after this etching was equivalent to #600. Example 2 The same material as in Example 1 was sprayed onto the surface of a vacuum molding die for obtaining a cube-shaped molded product to give it a matte finish.

1.5m7! Holding the L-thick ABS sheet in a vacuum forming clamp, the furnace temperature was 240°C and the heating time was 80 seconds.
Immediately after melting with EC, vacuum molding was performed in the above-mentioned mold at room temperature.

Table 1 shows the matte state of this cup-shaped molded product. Example 3 Alumina-titania powder material (#131 manufactured by Dai-ichi Metco Co., Ltd.) was sprayed on the surface of a compression molding die for obtaining a flat plate-shaped molded product to give it a matte finish.

Fill this mold with polyethylene pellets and set the mold temperature to 2.
Compression molding was carried out at 00°C and a mold clamping pressure of 1001<g/CrA. After cooling, the molded product was taken out and its faded state is shown in Table 1. The roughness of the mold was equivalent to #150.
The matte metal molds made by blasting have the following advantages over molds made by conventional etching, sandblasting, matte plating, etc.

(1) The surface of the mold has not only rough unevenness but also microscopically a complex shape in which even smaller unevenness is added to the unevenness itself, so that the matting effect of the molded product is large. (2) Mold production is done in one step, which is quick and inexpensive.

Claims (1)

[Claims] 1. A method for producing a matte processing mold for a synthetic resin molded product, which is characterized by forming a finely uneven metal coating on the surface of the mold by spraying.