JPS59101320A - Mold - Google Patents

Abstract

PURPOSE:To obtain a mold wherein tailings are prevented from adhering to it when molding is effected, and the releasability is improved, by which a molded item good in quality can be provided, by providing the die surfaces with coated films of ceramic or a solid lubricant by high-frequency sputtering. CONSTITUTION:A high-frequency sputtering apparatus includes a pair of electrodes 2, 2' each having cooling water circulating pipes 1, 1' in such a way that they are opposed to each other in a reaction tank 4 having an exhaust cylinder 3. A mold 5 to subjected to sputtering treatment is placed on the lower electrode 2. A target 6 that comprises ceramic or a solid lubricant that is formed into a disk by press molding is attached to the upper electrode 2' and argon gas or the like is introduced via a line 8. A high frequency voltage is applied by a high frequency power source 10 to change a switch 13, and a shutter 14 is opened to effect sputtering, so that the die surfaces 21-24 of the mold are coated with thin films 31-34 to obtain the intended mold.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mold for molding. More specifically, it prevents scum from forming during rubber and plastic molding, and improves mold releasability.
This invention relates to a mold for molding.

Generally, molds used for molding rubber and plastics are plated with hard chrome. Molding molds, including this type of mold, have traditionally had problems with scum buildup and mold releasability. That is, depending on the type of rubber or plastic to be molded, the molded product or a part thereof may stick to the mold and cannot be released cleanly from the mold. Therefore, in order to improve mold releasability, it is common practice to spray a mold release agent onto the molding surface of the mold, but even if this is done repeatedly, the adhesion of debris increases little by little, so the plating surface It will start to get cloudy and gradually become difficult to release from the mold. For this reason, the mold is cleaned every time the mold is molded several times. When the deposits cannot be removed sufficiently by cleaning alone, the plating must be regenerated, and the number of times the plating is regenerated increases depending on the number of times of cleaning.

Additionally, when bonding rubber to metal or plastic, this is often done at the same time as vulcanization, but if the adhesive contains components that generate corrosive gases, pinholes in the plating may occur. Corrosion occurs from the scratched area, so re-plating is often necessary.

Furthermore, when a mold release agent is used, although mold releasability is improved, the temperature of the molding surface drops, so electric heat must be supplied each time to maintain the temperature constant. No. Furthermore, the mold release agent may affect the quality and defective rate of the molded product.

The shortcomings of the conventional technique of applying a mold release agent to the molding surface of the mold can be resolved by providing a coating thin film of ceramic or solid lubricant with excellent heat resistance, corrosion resistance, moldability, etc. on the molding surface by high-frequency sputtering. The inventors have found that the following problems can be solved.

FIG. 1 of the drawings shows an outline of an apparatus used in the high frequency sputtering method applied in the present invention. That is, a pair of electrodes 2, 2', each provided with a cooling water circulation pipe 1.1', are placed in opposing positions in a reaction tank 4 having an exhaust gas n3. And the lower electrode (2)
A mold 5 for sputtering is mounted on the top, and a target 6 press-molded with ceramics or solid lubricant into a disk shape, for example, 60W in diameter and 5cm in thickness, is mounted on the upper electrode (2). Installed. Here, as the ceramic, for example, silicon carbide, titanium carbide, boron nitride, etc. are used, and as the solid lubricant, for example, molybdenum disulfide, boron nitride, etc. are used.

In the sputtering process, the air in the reaction tank is first evacuated from the exhaust pipe using a vacuum pump (not shown) such as an oil diffusion pump to reduce the pressure to 10" Torr or less, and then the barrier pull valve 7 is adjusted. While doing so, introduce argon gas etc. from line 8 to reduce the pressure inside the reaction tank to 10-'
The order is Torr.

The main valve (not shown) of the exhaust stack is now adjusted to provide a pressure on the order of 104 to 10° Torr, preferably 6 x 10-5 to I x 10' Torr. If the pressure of argon gas is lower than this, the discharge will not be continuous, and if the pressure is higher than kneading, not only will the sputtering speed drop significantly, but the discharge will also become unstable, making it impossible to form a homogeneous coating thin film. I can't. In addition, the code|symbol 9 is a vacuum gauge.

The operation involves connecting a switch 12 to a high frequency power source (13,56 MB2) 10 and a matching box (power meter) 11 to apply a high frequency voltage to clean and activate the mold surface, reduce pinholes, and form a thin film. After improving the adhesion of the target, stop the discharge, switch to the switch 13, discharge again, this time remove the dust and oxide layer on the target surface, open the shutter 14 without stopping the discharge, and move the target. Sputtering is performed to form a thin film of ceramics or solid lubricant on the mold surface, and when the desired film thickness is obtained, the discharge is stopped, the introduction of argon gas, etc. is stopped, and the main valve is closed. , by removing the treated mold from the reaction vessel.

Thin coatings of ceramics or solid lubricants formed by radio frequency sputtering are generally about 5 to 0.1
μm1 It preferably has a thickness of about 1 μm, and is characterized by not only excellent mold releasability but also good adhesion to the mold molding surface substrate and fewer pinholes. As a result, the following effects can be obtained.

(1) Due to its excellent mold release properties, there is less scum during molding of rubber or plastic, and there is no need to apply a mold release agent to the molding surface, which was conventional. This not only eliminates the negative effects of using a mold release agent that worsen the quality and defective rate of molded products, but also shortens and simplifies the molding process, and reduces the temperature on the molding surface. It does not have the effect of reducing power consumption.

(2) Since the degree of scum buildup on the molded product is suppressed, the life interval for mold cleaning can be significantly extended.

(3) A corrosion-resistant coating thin film with few pinholes is provided on the molding surface of the mold, and this thin film also covers pinholes in the plating layer, so corrosion of the mold is prevented.
The power life interval for plating regeneration becomes even longer.

(4) When regenerating the formed coating thin film of ceramics or solid lubricant, it is difficult to remove it with acid or alkali due to the corrosion resistance of this film, but the thickness is approximately 1 μm.
Since it is thin and physically adhered to the substrate with a thickness of about m, it can be easily recycled by scraping it off with emery paper or the like.

Next, the present invention will be explained with reference to examples.

Example 1 Each molding surface of each part 21 to 24 of an oil seal molding die shown as a vertical cross-sectional view in FIG. 2 of the drawings was coated with about 1.
Coating thin films 31 , 32 of silicon carbide or molybdenum disulfide with a thickness of μm.

33 and 34, respectively, and a rubber compound made of acrylic rubber, carbon black, silicon oxide, and graphite is sealed in the space 15 formed therein.
Vulcanization was carried out under the conditions of 00℃, 150 yen for 2.4 minutes,
The operation of forming the oil seal was repeated.

When a mold having a thin silicon carbide coating film on the molding surface was used, no abnormalities were observed in either the mold or the vulcanized product after 640 continuous vulcanization moldings.

In addition, when using a mold with a thin molybdenum disulfide coating on the molding surface, scum was observed on the edges of the mold at the 431st time, and a small plating layer was also observed on the molding surface. Peeling was observed.

When this mold was used for vulcanization molding without high-frequency sputtering treatment and while applying Ichitfliiltf molding agent, scum formed (7
) occurred, and the mold needed to be cleaned at that point.

Example 2 Using another mold (same shape as in Example 1, differing only in size), its molding surface was subjected to high-frequency sputtering treatment with silicon carbide or molybdenum disulfide in the same manner as in Example 1, and epichlorohydrin rubber, NBRN n9 Vulcanization molding from a rubber acetate compound consisting of lead oxide, gelaphite and silicon oxide was performed at 180°C and 150~. When the vulcanization was carried out for 6 minutes, no abnormality was observed in either the mold or the vulcanized product after 50 or more continuous vulcanization moldings.

When vulcanization molding was performed using this mold while applying the mold release agent described in Example 1 without high-frequency sputtering treatment, scum formed after about 201 cycles. The mold needed cleaning.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an apparatus used in the high frequency sputtering method applied in the present invention. (8) FIG. 2 is a longitudinal cross-sectional view of a mold for forming an oil seal subjected to high-frequency sputtering according to the present invention. (Explanation of symbols) 2.2'... Electrode 4... Reaction nucleus 5... Molding mold 6.・・・・・・
...Target 15 for ceramics or solid lubricant ...Mold space 21 ~
24...Mold part 31-3 for oil seal molding
4...Yoshi Yoshi, Patent Attorney for Coating H Membrane 1) Toshio Diagram 1

Claims (1)

[Claims] 1. A molding die in which a coating thin film of ceramics or solid lubricant is provided on the molding surface of the mold by high-frequency sputtering.