JPH01166911A - Synthetic resin molding die - Google Patents

Abstract

PURPOSE:To facilitate the releasing of a synthetic resin molded item from a molding die and obtain the synthetic resin molded item, which is excellent in mirror-smoothness without clouding or the like by a method wherein a fluorine-containing metallic film is formed on the molding surface of the molding die by sputtering in fluorine-containing gas atmosphere. CONSTITUTION:A fluorine-containing metallic film is formed on the molding surface of a molding die by sputtering in the atmosphere of fluorine-containing gas such as fluorine gas, carbon tetrafluoride, tetrafluoroethylene and the like. In case of the surface of glass, which is normally used as mold material, since etching or cleaning by the order of several Angstrom - several ten Angstrom is developed by means of ionized fluorine, the improvement of the adhesion of the film to the mold material results. Further, the deficiency of fluorine, which occurs during the formation of the film is replenished. Or, since fluorine-containing polymerized film is present in the film, low stress composite is produced, resulting in allowing to form fluorine-containing metal excellent in releasability.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a mold for synthetic resin molding that has excellent mold release properties from resin molded products and is capable of producing resin molded products with good specularity. be.

[Prior art]

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, or a sufficient mirror surface cannot be obtained.

Therefore, especially when molding optical parts made of synthetic resin, a mold with excellent specularity such as glass is used, and since the specularity of this mold is transferred to the molded product with strong adhesion, epoxy After the resin hardens, the molded product does not easily release from the glass mold. 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 the synthetic resin molded product 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. Since cloudiness occurs in the molded product, it is not possible to obtain a coating that is completely satisfactory as an optical component.

In order to improve the mold releasability of the mold surface of the mold, magnesium fluoride (Mi F2 >, calcium fluoride (Ca
F2), it is effective to form a thin film of fluorine-containing metal such as barium fluoride (BaF2) on the mold surface.
Recently, it has become well known. However, in terms of durability, the above-mentioned thin film formed using in-shell Ar gas as a carrier gas had a limit of 70 to 220 cycles. The causes of this are thought to be a lack of fluorine, which greatly contributes to the adhesion to molds such as glass and mold releasability, as well as cracks caused by stress in the film. This was developed after careful consideration to prevent fogging, etc. by forming a release film on the mold that makes it easy to release the synthetic resin molded product from the mold and transfers the specularity of the mold to the molded product. The first objective is to obtain a synthetic resin molded product with excellent specularity without any scratches, and further,
The second purpose is to improve the method of forming a mold release film and improve the durability of the mold release film.

[Structure of the invention]

The present invention is a synthetic resin molding die characterized in that a thin film of a fluorine-containing metal is formed on the mold surface of the molding die by sputtering in an atmosphere containing a fluorine-containing gas. 2゜In the fluorine-containing gas heater of the present invention, fluorine gas (
F2>, carbon tetrafluoride (CF4), tetrafluoroethylene (02F4), hexafluoroF2), calcium fluoride, (CaF2), barium fluoride (Ba F2), etc. can be used, but are not limited to these. It's not something you can do.

In the present invention, when forming a thin film of a fluorine-containing metal by sputtering, not only Ar but also a fluorine-containing gas is mixed as a carrier gas. Etching and cleaning can be done by several to several dozen people using fluorine, which greatly improves adhesion.
In addition, it supplements the slight fluorine deficiency during film formation,
Alternatively, since the film contains a fluorine-containing polymer film, a low-stress composite is generated, and a fluorine-containing metal with excellent mold release properties can be formed. - The fluorine-containing gas to be mixed here is Ar. The amount is preferably 1 to 20%.The reason for this is that if it is less than 1%, the etching and cleaning effect on the mold surface and the effect of compensating for the lack of fluorine are small.
In the above case, the film formation rate becomes slow, which causes a big problem in production. ``The thickness of this thin film varies depending on the material and purpose of the molded product, but it is appropriate that there be 500 to 3,000 people, preferably 1,000 to 1,500 people in the shell.5
This is because if the thickness is less than 00 Å, the number of times it can be used is small, and if it is more than 3000 Å, cracks are likely to occur due to the internal stress of the thin film.

In the present invention, the synthetic resin may be molded by any method such as compression molding, transfer molding, injection molding, or cast molding. The synthetic resin used for molding is not particularly limited, but epoxy resins that have high adhesion to the material used for the mold,
The present invention is effective when using phenol resins, unsaturated polyester resins, diallyl phthalate resins, ultraviolet curable resins, etc., and is particularly effective when molding optical parts from epoxy resins, unsaturated polyester resins, etc.

Further, the present invention is particularly suitable as a mold release film for a mold for obtaining a molded product having a large ratio of diameter to thickness (for example, 100 times or more) and having a problem with mold release properties.

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

Example 1 A glass plate with a mirror surface was coated with a thickness of 2 by sputtering.
000 CaF2 films were formed. The sputtering conditions are: substrate temperature: 120°C, fluorine gas pressure: 3 x 10
The temperature was -5 Torr, and Ar was further introduced at a rate of 3 x 10 -3 Torr.The film formation rate was 250 people/min.

Next, a composition consisting of an epoxy resin and a curing agent having the following formulation was prepared.

Blended composition A Bisphenol A type epoxy resin 100 Parts by weight Methylhexahydrophthalic anhydride 90 〃 2,6-ditertiary-butyl-1-hydroxytoluene 1, O 〃 2-ethyl-4-methylimidazole 0.151 / Compounded composition B Alicyclic epoxy resin 100 Parts by weight Methyl hexahydrophthalic anhydride 125 〃 2.6-ditertiary-butyl-1-hydroxytoluene 1.0 〃 2-ethyl-4-methylimidazole 2.5 〃 The above blended composition is mixed so that the ratio of A and 8 is 1:1 to obtain a casting resin composition.

A cast molding mold was prepared using a glass template on which a CaF2 thin film was formed, and the above acid anhydride-curable transparent epoxy resin was poured into the mold and cured by heating. The cast product was easily released from the mold without damaging the glass, the mirror surface of the glass was accurately transferred to the surface in contact with CaF2, and there were no defects such as clouding.

In addition, the CaF2 mold release film sputtered in an atmosphere containing fluorine gas had strong adhesion to glass, and had good mold release properties even after repeated use of 300 times or more. Example 2 A glass plate with a mirror surface was coated with a thickness of 1 by sputtering.
500 people formed CaF2. The sputtering conditions were such that the substrate temperature was 100° C., the gas pressure of tetrafluoroethylene was 6×10′ Torr, and Ar was further introduced to increase the pressure to 3×10 −3 Torr. Film formation speed is 300
The rate was 0 people/minute.

Next, as in Example 1, an acid anhydride curing agent-based transparent epoxy resin was cast into a mold, and as a result, it had good mold releasability even after repeating 350 times or more.

Comparative Example 1 3×10-3 Ar only without mixing fluorine-containing gas
A thickness of 20 mm was formed by sputtering in an atmosphere of Torr.
A casting mold with a CaF2 thin film formed thereon was prepared, and an acid anhydride curing agent-based transparent epoxy resin was cast in the same manner as in Example 1. As a result, the mold could be released up to approximately 80 times. However, if the molding was continued beyond this point, the mold release effect would be lost and mold release would be difficult.

Comparative Example 2 A casting mold was prepared using a glass template coated with stearic acid, and an acid anhydride curing agent-based transparent epoxy resin was cast in the same manner as in Example 1. As a result, cloudy transfer was observed. In the second casting, the mold release effect disappeared and mold release was difficult.

Comparative Example 3 A casting mold was made from the glass plate shown in Example 1 on which the Ca F2 thin film was not formed, and the same transparent epoxy resin as in Example was poured into the mold and cured.

The amount of cast material was difficult to release from the mold, and an attempt was made to forcefully release it, resulting in damage to the glass.

〔Effect of the invention〕

As described above, in the present invention, if synthetic resin is cast and molded using a mold on which a thin film of fluorine-containing metal is formed by sputtering in a fluorine-containing gas atmosphere, the synthetic resin molded product can be easily removed from the mold. A product that can be released from the mold and has an excellent mirror surface can be obtained. In addition, the durability of the mold release film is excellent, especially for optical parts such as synthetic resin substrates for optical storage media where a mirror surface on the surface of the molded product is important.
The effects of using the synthetic resin mold of the present invention are extremely large.

Claims (1)

[Claims] 1. A synthetic resin molding mold, characterized in that a thin film of a fluorine-containing metal is formed on the mold surface by sputtering in an atmosphere containing a fluorine-containing gas.