JPS60166422A - Molding method of plastic lens - Google Patents

Abstract

PURPOSE:To prevent the generation of defectives due to a peeling between a mold and a plastic raw material, and to improve productivity by using the mold in which the periphery of a lens forming concave surface section in a concave mold is roughened. CONSTITUTION:The periphery of a lens forming concave surface section is roughened in a concave mold 1', and the concave mold is held to a convex mold 2 by a tape 4 for a gasket. The inside of a cavity shaped between the concave mold 1' and the convex mold 2 is filled with a liquefied plastic raw material. A peripheral roughening section 5 in the lens forming concave surface section of the concave mold 1' may have approximately the degree of surface roughness through grinding by sand rubbing. Accordingly, adhesion between the plastic raw material and the concave mold is reinforced by roughening the periphery, and the plastic raw material can resist contractile force generated by a polymerization process, thus preventing the generation of a peeling.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of molding a plastic lens, and more particularly to a method of molding a plastic lens by curing a plastic raw material in a cavity formed by an improved concave mold. It is.

Plastic lenses are sometimes manufactured by injection molding or compression molding of thermoplastic resins such as polycarbonate and poly(meth)acrylates, but in order to manufacture plastic lenses with excellent performance and physical properties, Cast molding is performed.

As a liquid hardening compound that is a raw material for plastics, α
, monomers and other prepolymers having one or more β-unsaturated groups, monomers and other prepolymers having α- and β-unsaturated groups and condensation-polymerizable groups such as epoxy groups, and their prepolymers, which can be cured by low polymerization. There are various compounds. Specifically, for example, diethylene glycol bisallyl carbonate, (
These include meth)acrylic acid ester, diallyl ester, 1-lylylisocyanate-1-, and the like.

Among plastic lenses, eyeglass lenses in particular require a high degree of accuracy, and are also impact resistant.

High physical properties such as scratch resistance and transparency are required.

Currently, diethylene glycol bisallyl carbonate-1 is widely used as a raw material for eyeglass lenses. This diethylene glycol bisallyl carbonate
Copolymers based on lJt homopolymerization of 1- or so-copolymer have excellent physical properties such as transparency, impact resistance, and scratch resistance, and are the most excellent for use in eyeglass lenses. It is known that

Cast molding of plastic lenses involves filling the cavity 4 between the two molds held in the casken 1 with a plastic raw stone such as a monomer, and then 11. Tubing is a process of hardening the lens by heating, etc., then removing the mold and taking out the lens. In step 1 of ``Assembling a cavity with two molds holding gaskets'', the gasket I- is made of a flexible material such as rubber, extomer, or relatively soft synthetic resin.

The two molds are usually made of glass and have a cylindrical to disc shape. One of the molds is a concave mold having a mirror-polished concave surface necessary for forming the lens surface, and the other mold is a concave mold with a mirror-polished curved surface. Similarly, the mold has a convex mold in which the convex surface necessary for forming the lens surface has a mirror-polished curved surface. The cavity formed by the bending mold is filled with liquid plastic raw material, and the cavity is sealed with a gasket 1- to prevent leakage. Next, the mold filled with the raw material is placed in a heating furnace or the like to harden the plastic raw material. In order to minimize distortion of the lens and ensure uniform polymerization, curing often requires at least several hours, usually over a day and a night. However, even if plano lenses are manufactured by the darning method, polymerization shrinkage occurs during the polymerization process in which the plastic raw material is converted into a polymer, and the assembled mold is removed from the heating furnace.
When the lens inside is taken out, delamination often occurs between the plastic material 4'11 and the mold. This is especially noticeable with negative power lenses. Peel it like this 1
1 JIA Plastic lenses that have been damaged do not exhibit the curved surface necessary for lenses, that is, accurate power, and their optical characteristics change, making them unsuitable for use as lenses. This is a major cause of the decline.

Therefore, the present inventor conducted various research and studies in order to solve the problem of polymerization peeling that occurs between the plastic raw material (and the mold) in the conventional cast molding method for negative power lenses by improving the mold. As a result, we discovered that the periphery of the lens-forming concave part of the concave mold has a surface area of 141 A, and that the occurrence of peeling is reduced by using the mold.This led to the completion of the present invention. .

That is, the present invention softens a 2 fl, Among the two molds, the concave mold has a roughened surface around the concave surface for lens molding. This is a method for molding a plastic lens, characterized by molding within a cavity formed by a mold made of a plastic lens.

The present invention will be explained in more detail with reference to the drawings.

Figure 1 is a cross-sectional view of a mold body in which a plastic raw material is filled into a cavity formed in a cast mold for a negative power lens assembled by a conventional concave mold and a convex mold. be. The convex mold 1 and the convex mold 2 are held together by a gasket tape 4. A cavity 3 is formed between the convex mold 1 and the convex mold 2, and the cavity is filled with plastic raw stone. The liquid plastic raw material initially filled in the cavity undergoes contraction during the process of being heated and polymerized and hardened, that is, one polymerization contraction, and a contraction force is generated in the direction of the arrow in Figure 1. The size of the contraction force is small at the center of the mold and largest at the periphery, as indicated by the arrows. As a result, the adhesive force between the mold and the plastic raw material resists the shrinkage force, and it is peeled off within 1L.
It will end. Peeling of the plastic raw material from the mold is particularly likely to occur in plastic lenses with a strong negative power, and this is because the periphery of a lens with a strong negative power is thicker than the center, and therefore the shrinkage force is greater. This is due to a number of reasons.

A method of molding a plastic lens according to the present invention is illustrated in FIG. That is, FIG. 2 shows that, using the molding force method of the plastic lens of the present invention, a mold in which the periphery of the four surfaces of the concave mold is roughened and a normal concave mold are used. Kumisa 7 Tera J
FIG. 2 is a cross-sectional view of a mold assembly for cast molding of a negative power lens. The convex mold 2 has a roughened surface around the lens forming concave part, and the convex mold 2 is composed of a gasket 1 and a gasket 4.

A cavity 3 is formed between the convex mold 1' and the convex mold 2, and the cavity is filled with a liquid plastic raw material. The periphery of the lens-forming concave portion of the concave mold 1' is roughened over the entire periphery of the hemostatic portion 5 along the circumference by 7 eaves, preferably from 1 to 5111 m, from the mold end.

The roughness is not particularly limited, but it is sufficient to have a surface of about m degree by sand-sand polishing, and if the lens has a strong degree, it should be coarse, and if it is weak, it should be fine. It is preferable to do so. By roughening the periphery in this way, the adhesive force between the plastic raw material and the concave mold is strengthened, and the plastic raw material is able to resist the shrinkage force generated by the polymerization process, thereby preventing the occurrence of peeling. becomes possible.

The method of roughening the peripheral roughened portion 5 of the lens forming concave portion of the concave mold 1' is not particularly limited. For example, in the mirror polishing process of the lens forming concave part, the entire surface is sanded and then only the surface of the pond is mirror polished, excluding the peripheral roughened part. Alternatively, after the entire surface is mirror polished, the peripheral roughened part is polished to a mirror finish. Any method is fine, such as sanding the chisel.
The former method is preferred; however, the Sandplus 1 method can also be used to roughen the surface.

The mold in which the periphery of the lens-forming concave portion of the 5 convex mold I- in the present invention is roughened can be used in combination with a normal convex mold to form a plastic lens. A plastic lens can also be molded by combining a mold with a convex portion and a flat portion, for example, provided around the periphery.

In the present invention, the liquid plastic raw material filled into the cavity formed by the mold is one containing a curable compound as a main component, and one example is diethylene glycol-λ lebis allyl carbonate 1-9 (meth )
Acrylic acid ester, diallyl ester, 1-lylylisocyanurate I-, etc. are mentioned, and diethylene glycol bisallyl carbonate-1- is particularly preferred. The polymerization curing method for liquid plastic raw materials involves placing a mold filled with liquid plastic raw materials in a heating furnace, etc.
Curing can be carried out by a conventional method of curing by heating polymerization.

The plastic lens molding method of the present invention is effective for lenses with negative power, especially lenses with strong negative power. According to the method of the present invention, molds and plastics due to polymerization shrinkage during the polymerization process of liquid plastic raw materials can be molded. This has the excellent advantage that it is possible to prevent the production of defective products due to thorns with raw materials, and therefore productivity is significantly improved.

EXAMPLES The present invention will be specifically explained below with reference to Examples, but the present invention is not limited by these Examples.

Example: After sanding the entire surface of the concave lens forming mold of a -8 degree concave mold made of glass, a mirror finish was applied to the entire circumference of the mold, leaving the area up to 5 nNn from the mold edge. conduct,
It was made in a concave mold in which the periphery of the lens-forming concave part was roughened. The roughness of the roughened area is the surface roughness,! 1
(Koita Research Institute RJ)
ta) was 5μ. In this way, I assembled the convex mold made with the convex mold for micro-nano and 8-degree lens molding, and assembled it with n-Jj'! ! (
A cavity was formed between the moldings 1 by holding the periphery of the gasket 1 with a tape made of plastic having a diameter of 1.

In the formed cavity, diisopropyl baroxycarbonate-1-(Vylor J'PI'
; Nippon Oil & Fats fn3 product) After filling with liquid plastic raw material to which 4% by weight was added.

Seal it with the above gasket 1- tape to prevent leakage.
Ta. Next, the mold filled with the plastic raw material is placed in a heating furnace, heated gradually from room temperature to 90°C over 10 hours, held at 90°C for another hour, cooled, and removed from the mold. I took out the molded lens. The molded lens did not peel off from the mold and showed the correct value of minus 8 degrees in the lens power test.

10 lenses of minus 8 degrees were produced using the same method as described in Section 2, but there were no defective products due to polymerization peeling, etc., and all of the lenses showed acceptable values when tested for lens power.

Comparative Example Same as the example; a conventional concave mold and a convex mold for molding a minus 8 degree lens molded by crow were combined and held together with gasket tape to form a cavity between the molds.

The formed cavity was filled with a liquid plastic raw material prepared in the same manner as in the example, and heated in a heating furnace under the same conditions as in the example to mold a lens. The molded lens had peeled off from the mold and did not show a value of minus 8 degrees in the lens power test.

Five lenses of minus 8 degrees were manufactured in the same manner as described above, but four of them peeled off from the mold and did not show correct values when tested for lens power.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a molded silk solid body in which a plastic material T is filled in the cavity of a casting mold for a negative-power lens assembled by a conventional mold, and FIG. It is a cross-sectional view of a molded silk solid for cast molding of a negative power lens assembled by a mold in which the periphery of the lens forming concave part of the concape mold is roughened. Surface conversion mold 2: Compex mold, 3: Cavity. 4: Gasket tape, 5: Hemostasis part No. 2 / Sprouting bud 2.

Claims (1)

[Claims] Two molds with curved surfaces for molding plastic lenses are made, and in the cavity formed between the two molds, a Plus Deck JLj1) containing a liquid curable compound as a main component is placed. In the method of molding a plastic lens by hardening, among the two molds, the concave mold is molded in a cavity formed by a mold in which the periphery of the concave surface portion for lens formation is stopped by bleeding. A method for molding a plastic lens characterized by