JPS6127212A - Mold for synthetic resin - Google Patents

Abstract

PURPOSE:To enable manufacture of a synthetic resin formed piece free from cloudiness, etc. and excellent in mirror finish by a method wherein a silicone- containing mold release film, a fluorine-containing mold release film or a polyolefin mold release film is provided by the plasma copolymerization method on the mold surface in contact with synthetic resin. CONSTITUTION:Organic compound is used for the film material provided on the forming surface of a mold for synthetic resin. In this case, hexamethylene disiloxane, tetramethyl disiloxane, ethylene tetrafluoride, monochloro-ethylene-trifluoride propylene hexafluoride, ethylene, butylene, isobutylene, pentene, 2-methyl pentene, etc. are excellent in releasability from synthetic resin and adhesion to molds composed of metal, glass, ceramics, etc. The plasma copolymeric film of these monomers is provided with crosslinking structure to resist temperature 100 deg.C or higher and a strong point of satisfying necessary properties as the mold releasing agent on a mold for three-dimensional hardening synthetic resin. The thickness of the film varies according to the material or usage of a formed piece but 500-3,000Angstrom is generally suitable.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mold for synthetic resin molding that has excellent mold release properties from resin molded products and can produce resin molded products with good specularity.

In molding synthetic resins, when removing a molded article from a mold, materials with strong adhesive properties such as epoxy resins, unsaturated polyester resins, and phenol resins have poor releasability from the mold.

In such cases, a method of applying a mold release agent to the mold is common, but the molded product often becomes cloudy due to the mold release agent, and a sufficient mirror surface cannot be obtained.

Particularly when molding optical parts made of synthetic resin, it is conceivable to use a mold having excellent specularity, such as glass, and to transfer the specularity of this mold to the molded product.

However, in the case of an epoxy resin molded article and a glass mold, for example, the adhesion between the two is strong, so that the molded article is not easily released from the glass mold after the epoxy resin is cured.

Furthermore, cracks often occur in the glass mold due to stress caused by molding shrinkage of the epoxy resin.

In order to improve the mold release between such synthetic resin molded products and the molding mold, there is a method of applying a mold release agent to the mold as described above, but in this method, the mold release agent is transferred to the molded product, thereby preventing molding. Since the product becomes cloudy, it is not possible to obtain an optical component that satisfies the bottom of the product.

The present invention was developed after intensive study to improve these drawbacks, and includes a mold release film that facilitates the release of the synthetic resin molded product from the mold and that can transfer the specularity of the mold to the molded product. The purpose of this method is to obtain a synthetic resin molded product having excellent specularity without clouding or the like.

In the present invention, ethylene, butylene, imbutylene, pentene, 2-
Related to a synthetic resin mold in which a thin film is formed using organic compound monomers such as methylpentene, ethylene tetrafluoride, ethylene monochlorotrifluoride, vinylidene fluoride, propylene hexafluoride, hexamethyldisiloxane, and tetramethyldisiloxane. The obtained thin film adhered firmly to the mold.

When synthetic resin is injected into the mold of the present invention and molded, the adhesion between the synthetic resin and the thin film formed on the mold is much smaller than the adhesion between the mold and the thin film, so this thin film separates during molding. It has the advantage of acting as a mold film.

Among optical parts, this method is particularly effective in the case of synthetic resin molded products that strongly require specularity, such as substrates for optical storage media, because the specularity of the mold is transferred to the molded product without being impaired at all.

In the present invention, an organic compound is used as a material for the N film formed on the molding surface of a synthetic resin molding die, and examples include hexamethylenesiloxane, tetramethyldisiloxane, ethylene tetrafluoride, and monochlorotrifluoride. Ethylene, propylene hexafluoride, ethylene, butylene, isobutylene, pentene,
2-methylpentene and the like have excellent mold releasability from synthetic resins and adhesion to molds made of metal, glass, ceramic, etc.

Since the plasma polymerized film of these monomers has a crosslinked structure, it has heat resistance of 100° C. or more, and has the advantage of satisfying the necessary characteristics as a mold release agent for a three-dimensionally curable synthetic resin molding mold.

The thickness of such a thin film varies depending on the material and purpose of the molded product, but generally 500 to 3000 Å is appropriate.

If the thickness is less than 500A, the number of times it can be used will be reduced, and if it is more than 300OA, the thickness distribution accuracy will deteriorate, making it unsuitable.

In the present invention, the synthetic resin may be molded by any method such as compression molding, transfer molding, injection molding, cast molding, etc.

Synthetic resins are not particularly limited, but the present invention is effective when using epoxy resins, phenol resins, unsaturated polyester resins, diallyl phthalate resins, etc. that have high adhesion to the material used for the mold. This method is particularly effective when molding optical components using ultraviolet curable resins such as unsaturated polyester resins.

Next, examples of the present invention will be shown.

Example 1 A hexamethylnosiloxane polymeric thin film was formed on a glass plate having a mirror surface by plasma polymerization.

The polymerization conditions are as follows. Apparatus: Plasma polymerization apparatus model LCVD-12 manufactured by Shimadzu Corporation. Pretreatment: After washing with detergent and drying, oxygen plasma etching was performed.

Moamar gas used; hexamethyldisiloxane (Ald
RIC-11 reagent), vacuum degree: 0.005 T initially
After evacuation to 0.2 Torr, power: 1
00W, open during polymerization; 3 minutes.

The thickness of the obtained thin film was 800A. Next, the contact angle was measured using pure water using a contact angle measuring device manufactured by Elma Optical Co., Ltd. The results are shown in Table 1.

It was proven that the silicone polymer film formed made the glass plate hydrophobic.

Table 1: Measured values are average values for n:6 Example 2 An ethylene polymer film is formed on a glass plate having a mirror surface by plasma polymerization.

The polymerization conditions are as follows. Equipment: Plasma polymerization equipment manufactured by Shimadzu Corporation, Pretreatment: Oxygen plasma etching after cleaning with detergent and drying, Monomer gas used: Ethylene, Degree of vacuum: First evacuated to 0.005 Torr, then 0.5T
orr power: 50 W, polymerization time: 3 minutes.

The thickness of the obtained thin film was 1500A. Next, the contact angle was measured using pure water using a contact angle measuring device manufactured by Elma Optical Co., Ltd. The results are shown in Table 2.

It was proven that the formed ethylene polymer film made the glass plate hydrophobic.

Table 2

Claims (1)

[Claims] A mold for synthetic resin molding, characterized in that a silicon-containing mold release film, a fluorine-containing mold release film, or a polyolefin-based mold release film is formed on the mold surface in contact with the synthetic resin by a plasma polymerization method.