JPS6025710A - Transfer-molded item and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain a transfer-molded item having a worked fine surface that is suitable as a Fresnel lens or the like, by placing a substrate on a negative form of a silicone rubber on which a photo-setting resin is applied, and irradiating the substrate with an activating ray so that a positive form may be transferred to the substrate. CONSTITUTION:A negative form whose surface is fine is produced from a curable silicone rubber such as a two-component type silicone rubber, and then a photo-setting resin such as tetrahydrofurfryl (meth)acrylate or the like is applied on the negative form. Thereafter, a light transmitting substrate such as a glass plate is placed thereon, and an activating ray is projected using an ultraviolet projecting apparatus onto the silicone rubber or the substrate. Thus, a positive form is transferred from the negative form onto the substrate thereby producing the intended transfer-molded item. EFFECT:Precise transfer can be carried on even a large intended item.

Description

DETAILED DESCRIPTION OF THE INVENTION When manufacturing a plastic material having a finely machined surface, for example a 7 renel lens, injection molding or press molding is performed using a negative mold.

Injection molding is particularly difficult for large molded products due to precision and uniformity, and press molding takes a long time to manufacture due to air removal and precision, and the mold is easily damaged, reducing precision, resulting in high wear and tear. It has its drawbacks. It is also possible to use a negative mold to transfer a positive mold using a photocurable resin, but using a hard mold and applying a hard +1 layer to the hard mold will result in poor mold releasability and fineness. , III structure is not satisfactory, especially in the case of large-sized transcription.

The present invention has been achieved through research to solve the above problems.

That is, the present invention is a molded product in which a positive mold with a finely processed surface is transferred from a negative mold of silicone rubber onto a light-transmitting base material using a photocurable resin. This is a method for manufacturing this molded body.

This manufacturing method creates a negative mold with a fine surface using curable silicone rubber, and by irradiating the photocurable resin with actinic rays, the positive mold is transferred from the negative mold onto a light-transmitting substrate. It is characterized by

The molded product of the present invention has a finely processed surface, and examples thereof include a Fresnel lens and an optical disk''!f.

The silicone rubber used in the present invention has high tensile strength and commercially available silicone rubbers can be used, but two-component silicone rubber is preferred because it cures quickly. Silicone rubber is suitable because it can be irradiated with light from the silicone rubber side when photocuring later. Furthermore, since silicone rubber has low adhesion to the photocurable resin and is flexible, the negative mold can be easily peeled off by bending the silicone rubber from the cured resin surface. Negative molds of silicone rubber are made by pouring, for example, two-component silicone rubber onto a positive mold (mold, resin mold, etc.), defoaming if necessary, and curing it at room temperature or by heating.The cured silicone rubber is flexible. It also has excellent mold releasability, so it can be easily peeled off and a negative mold can be obtained.

In the present invention, a positive type is transferred from a negative type of silicone rubber onto a substrate, and a photocuring reaction of a photocurable resin is used as a transfer method. For example, a liquid photocurable resin is applied onto a silicone rubber negative mold, a light-transmitting substrate is placed thereon, and active light is irradiated from the silicone rubber side or the substrate side. When irradiated with the active light a+, the photocurable resin becomes a positive cured product having concave or convex surfaces corresponding to the convex or concave surfaces of the negative type, respectively. This cured product is then bonded to the substrate and becomes an integral part. When applying and curing the photocurable resin, vacuum is applied if necessary. By creating a reduced pressure state, when a finely machined surface is transferred, it is possible to prevent a decrease in accuracy due to bubbles.

There are various types of photocurable resins, including acrylic and polyene/
Polythiol-based products are easy to use, such as ruv-gn.
Known resins described in various literature such as "Curing Technology" [published by Sogo Gijutsu Center Co., Ltd.] or patent publications are used, but resins with good transparency are preferred.

In general, photocurable resins have good releasability from silicone rubber, and therefore, in the present invention, the transferred molded product can be easily peeled off from the negative mold.

On the other hand, it is preferable that the photocurable resin has high adhesion to the substrate to which it is transferred. The substrate is a light-transmitting material such as glass or transparent plastic, and in the case of glass, a cured product with high adhesion can be obtained by using a known silane coupling agent, and in the case of acrylic plate, a cured product with high adhesion can be obtained. By using tetrahydrofuryl (meth)acrylate as the photocurable resin, a cured product with high adhesiveness can be obtained.

It is preferable that the photocurable resin used has a low viscosity because it can sufficiently spread over the finely processed surface of the silicone rubber negative mold. In particular, a viscosity of 50 to 2,000 cps is preferred.

The photocurable resin is cured by irradiation with ultraviolet light.

Irradiation was carried out using a commonly used ultraviolet irradiation device F4. (Blacken/
It varies depending on whether it is a polythiol type, the type of mononu used, the type and negativity of the photosensitizer5,
The curing can be completed by irradiation of 000 mJ to 10,000 mJ.

As the photosensitizer, commonly used photosensitizers such as benzyl dimethyl ketal and benzoin ethyl ether can be used.

Next, the present invention will be explained by examples.

Example 1 A negative mold was made from a 30 crn square acrylic Fournel lens using transparent silicone rubber.

The curable silicone rubber used was manufactured by Toshiba Silicone Co., Ltd.
W-14-253, a base resin and a curing agent were mixed in a ratio of 10:1, degassed and cast, and after curing at 80° C.I., it was peeled off from an acrylic Fresnel lens and was easily and precisely removed. Next, using this silicone rubber mold, the photocurable resin (adhesive) shown in Table 1 was transferred to a glass plate and an acrylic plate to improve the mold releasability.
As a result of examining the accuracy, all were found to be good.

Furthermore, Table 2 shows the results of measuring the tensile strength and adhesive strength between acrylic plates using the photocurable resins shown in Table 1. When furfuryl methacrylate is used as tetrahide, stars showing particularly good durability can be seen.

Comparative Example 1 When the photocurable resin shown in Table 1 was transferred to an acrylic plate using a nichrome-plated mold, which was used as a substitute for the silicone rubber negative mold of Example 1, the mold release properties were poor, such as the convexities of all lenses being chipped. there were.

In the above Examples and Comparative Examples, light irradiation was performed using a Stanley black lamp at 10 mW/c, n
It was irradiated for 10 minutes at an illumination intensity of 1.

Photocurable resin (1) Epoxy ester 3002A (Kyoeisha Yushi Kagaku Kogyo) 15 I 2-hi)"D xy 3-7: f-SJL #v-77bhi λζr crery) 10 # Silane coupling agent A
-172 (Nihon Unicar Co., Ltd.) 0.5 #Benzoin ethyl ether 0.51 Epoxy ester 3002A 30 #Silane coupling agent A-1720,51 Benzoin ethyl ether 0.5# *+60°C after being left at -20°C for 2 hours The strength after 20 cycles is shown, with 2 hours of standing being one cycle.

Patent applicant Denki Kagaku Kogyo Co., Ltd.

Claims (1)

[Claims] 1. A molded product in which a positive mold with a finely processed surface is transferred from a negative mold of silicone rubber onto a light-transmitting base material using a photocurable resin. It is characterized by creating a fine surface negative mold using 2-curing silicone rubber, and by irradiating the photocurable resin with actinic rays, the positive mold is transferred from the negative mold onto a light-transmitting substrate. A method for manufacturing a molded body having a finely processed surface.