JPS63312132A - Manufacture of lens made of synthetic resin - Google Patents

Abstract

PURPOSE:To contrive to heighten the yield of production, while the inconvenience such as mold release caused in polymerization is prevented by a method in which when a liquid monomer or a liquid prepolymer loses fluidity due to gelation, a tape is removed from materials, and further polymerization is advanced and finished. CONSTITUTION:Two matrixes are positioned oppositely to each other and, a tape is wound around these matrixes, thereby fixing the matrixes. A liquid monomers or a liquid prepolymer is poured into between these materials, and then is polymerized and cured. The tape is removed from the matrixes, when the liquid monomer or the liquid prepolymer reaches gellike semicure, and its polymerization degree is in the range of 12-60%, preferably in the range of 14-50%. Then, the crack of the molded lens, the crack of the mold and its mold release, etc., do not occur. After the tape has been removed from the matrixes, curing is carried out in the heating medium containing oxygen generally. By such curing, the outer periphery of 1-2mm remains in uncured state, but when the periphery is polished, a molded object suitable for necessary condition as a synthetic resin lens, is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention provides a method for manufacturing synthetic resin lenses by a casting method, in which the liquid monomer or liquid prepolymer used gels. By removing the tape from the matrix when it loses its dynamic properties and allowing the polymerization to proceed and complete, it is possible to produce particularly spherical concave lenses with large edge thickness, concave lenses with at least one surface of the lens being aspherical, and large refractive power. The present invention relates to a method for manufacturing concave lenses with high yield.

(Prior art and its problems) In recent years, synthetic resin lenses have attracted attention for their excellent properties such as lightness and ease of processing.
It is widely used as a lens for 12.

Especially for eyeglass lenses, they have excellent optical properties and resistance to Ili.
Diethylene glycol bisallyl carbonate polymer is widely used as a material that has both striking and dyeing properties.

Spectacle lenses using this type of lens are generally manufactured by the following method. In other words, a polymerization catalyst and an ultraviolet absorber are placed in a gap formed by combining two glass molds with good surface precision and different radii of curvature, separated by an annular synthetic resin gasket that increases flexibility. A liquid monomer mainly composed of diethylene glycol bisallyl carbonate or a liquid prepolymer thereof is injected and completely cured in a heating furnace, the annular gasket is removed, and the glass mold is heated by thermal shock or This is done by removing the mold by driving a wedge between the molds or the like.

By the way, the problem with manufacturing synthetic resin lenses by casting liquid monomers or liquid prepolymers is that the polymerization shrinkage rate of the monomers or prepolymers is about 1.
Since JIE is always large at 3 to 14%, internal stress occurs during polymerization, causing the molded lens to release from the mold, leaving mold release marks on the lens surface, and the surface area of the lens is significantly impaired, resulting in a reduction in product yield. This results in a significant decrease in productivity.

Release from the mold during molding is noticeable when manufacturing concave lenses with large refractive power, and is particularly noticeable in spherical lenses and cylindrical refractive lenses whose refractive power is S-2,250 (D: Dioptor) or more. ) is −
0.25D or more and spherical refractive power (S: 5l) h(ir
It is very difficult to efficiently produce a synthetic resin concave lens with a sum (S+C) of -2.25D or more with good yield. Also, the refractive power of the lens to be molded (S
+C) is +3. If the lens is OOD or higher, in addition to mold release during polymerization, cracks in the mold or cracks in the lens during molding may occur, making it difficult to produce convex lenses with large refractive power in the same way as concave lenses with large refractive power. It is also very difficult to produce well and efficiently.

In order to solve such inconveniences, for example, polymerization is started at a relatively low temperature around 40°C so that the mold can follow the polymerization shrinkage of the polymer or prepolymer during molding. It is done slowly and over time. In general, various proposals have been made to improve the yield during molding. For example, using a relatively soft material such as ethylene-vinyl acetate copolymer as the annular gasket material, or devising the shape of the gasket as proposed in JP-A-56-27327, the gasket itself shrinks. Methods have been proposed to make it easier. In addition, it has been considered to use a highly flexible and easily shrinkable tape instead of the synthetic resin annular gasket, but even using tape does not completely solve the above problems. This is not a definitive method for manufacturing synthetic resin lenses with high refractive power with good yield.

[Background of the invention]

Cracks in molded lenses, cracks in molds, and release from molds that occur during the production of synthetic resin lenses occur when the reaction rate of liquid monomer or liquid prepolymer reaches 50% or more. . In order to reduce the yield of molded lenses, it is very effective to remove the tape that separates the two molds before problems such as the lens being molded separates from the mold. Furthermore, they discovered that by forming lenses using this method, the polymerization time was significantly shortened compared to conventional lens manufacturing methods, and completed the present invention.

[Means for solving problems]

Therefore, in the present invention, problems such as mold release are solved by removing the tape from the matrix when the liquid monomer or liquid prepolymer reaches a gel-like semi-cured state and allowing the polymerization to proceed further. , and aimed at shortening the polymerization time.

The present invention will be explained in detail below.

In the present invention, when the tape is removed from the matrix, the polymerization rate of the liquid monomer or liquid prepolymer is 12 to 60.
It is best to carry out between 14% and 5%
It is 0%. If the polymerization rate of the liquid monomer or liquid prepolymer is less than 12%, the injected liquid monomer or liquid prepolymer is still in a liquid state or in a very soft gel state, and it is impossible to remove the tape from the matrix.
Further, when the polymerization rate exceeds 60%, mz occurs during molding in a lens having a large refractive power in which at least one surface of the molded lens is an aspherical surface.

When a liquid monomer or liquid prepolymer is injected into a matrix separated by tape and heated in a heating medium such as a hot air oven, the polymerization rate is determined by quantifying the amount of residual catalyst or unsaturated groups in the monomer or prepolymer. Although it can be measured by analysis, it is possible to measure the polymerization rate at that time by measuring the heating conditions and heating time.

Typical tapes are cellophane tape, vinyl tape,
Cloth tape, paper tape, and other tapes can be used as they are, but if the tape is an adhesive tape, be careful when selecting it, as depending on the type of adhesive, it may have an adverse effect on the polymerization of the liquid monomer or liquid prepolymer. It takes. The thickness of the tape is 5 to 200 tIR1, preferably 20 to 100 m.

The mother molds are assembled by arranging two mother molds facing each other at a predetermined distance and then wrapping tape along the circumferential surfaces of the two mother molds in this state. It is preferable that the winding start end and the winding end end of the tape are butted against each other rather than overlapping both ends to prevent the formation of minute gaps and to prevent air from entering.

To remove the tape, simply peel off the tape wrapped around it from the matrix. Alternatively, it may be cut out using a knife or the like.

Curing after removal of the tape from the matrix is preferably carried out in a heated medium, usually in the presence of oxygen. When such a curing method is carried out, the outer circumferential parts 1 to 2 Jll of the molded synthetic resin lens remain uncured, but if the periphery is polished, the optical properties will be improved.

It is possible to obtain a molded body that meets the necessary conditions for a synthetic resin lens, such as strength. In addition, if the tape is not removed or curing is completed in an inert gas without oxygen, a synthetic resin lens with a hard outer periphery that does not require polishing can be obtained, but mold release may occur during molding. Easy and undesirable.

The synthetic resin lens according to the present invention can be molded in a shorter polymerization time than conventional methods. In other words, it is possible to set the curing rate of 1fff to around 45°C until the tape is removed, which is higher than the conventional method, and it is also possible to set the curing rate to 111, which is higher than the conventional method. It is also possible to raise the temperature of the medium in a short period of 20 hours or less.

The liquid monomer or liquid prepolymer that is the raw material for the synthetic resin lens according to the present invention is not particularly limited. Diethylene glycol bisallyl carbonate, generally referred to as CR-39 as mentioned above, is not limited to just that, but also diallyl carbonate, ethylene glycol bisallyl carbonate carbonates, diallyl phthalate, and tri-7lyl. Unsaturated alcohol esters such as isocyanurate and diallylbenzoate; unsaturated esters such as methyl methacrylate, glycol dimethacrylate, diethylene glycol dimethacrylate, and glycidyl methacrylate;
It may be combined with styrene, unsaturated polyester resin, other monomers having α,β unsaturated groups that are liquid at room temperature, or their prepolymers. However, hetamine and its prepolymers containing at least 40% by weight CR-39, preferably 60% by weight, are superior raw materials for synthetic allff lenses. Among the monomers and prepolymers mentioned above, monomers and prepolymers that can be used alone to form synthetic resin lenses include the allyl carbonates, unsaturated alcohol esters, unsaturated acid esters, etc.
There are unsaturated polyester resins, epoxy resins, and other monomers having α and β unsaturated groups and their prepolymers.

Seven polymers or prepolymers contain the above-mentioned liquid compound as a main component, but usually also contain a small amount of a radical polymerization catalyst. The radical polymerization catalyst may be any catalyst as long as it can initiate radical polymerization of 7J-mers or oligomers, but peroxides are preferred, such as benzoyl peroxide, 7J-bonate, , etc. In addition, colorants such as dyes, ultraviolet absorbers, fillers, and other various additives may be included.

The synthetic resin lens obtained by the present invention is dyed. Anti-reflection,
Prevents scratches. Prevention! It is possible to apply known techniques such as I.

(Example〕 The present invention will be explained in more detail with reference to Examples below.

Example 1 Diethylene glycol bisaryl carbonate (CR
-39: Product name manufactured by BBG Industries) 2
5Ny, di-isopropyl peroxyperoxydicarbonate (Verloyl IPP: trade name manufactured by NOF Corporation)
IN9, Contains 8g of Harisorb (T: external radiation absorber), W
The reaction was carried out at 40°C to 50°C until the solution viscosity reached 35 cps (calculated at 25°C) to obtain a liquid prepolymer with a polymerization rate of 4%. This liquid prepolymer was injected into a glass mold separated by cellophane tape (thickness: 35 μm) and placed in a hot air oven set to the conditions shown in Figure 1, and then placed in the oven for 2 hours and 30 minutes. At a certain point (indicated by point A in FIG. 1), the tape was removed and further completely cured in a hot air oven. The polymerization rate of the liquid prepolymer when the tape was removed was 16% (including a 4% polymerization rate of the liquid prepolymer).

Table 1 shows the results of various synthetic resin eyeglass lenses manufactured using this manufacturing method. In addition, the quality inspection was performed on the outer periphery of approximately 11
This was done after m polishing.

Table 1 (a) Expression power: Deck LM-88 lens meter
0) to measure the frequency of expression up to 0.0 ID (D=diopter) and measure the range of variation.

(B) Dyeing property: Dyeing for 3 minutes in a water bath at 87 to 88°C using a commercially available dye for plastic eyeglass lenses (Brown, manufactured by Suwa Seikosha Co., Ltd.), and measuring the transmittance of the dyed lens to 550n11. The stainability (%) was measured.

Comparative Example 1 Using the prepolymer of Example 1, various plastic eyeglass lenses were manufactured by polymerizing in a wind oven under the conditions shown in Figure 2 without removing the tape until the polymerization was completed.Table 2 shows the results. show.

Lenses with refractive power (S+C) of -2,00 [) or less are 80
Although we were able to obtain a good product rate of more than %, the refractive power (S + C
) of −2.25D or more and +3°00D or more, mold release occurred during molding, resulting in a decrease in yield.

Table 2 (a) Partial release: Refers to development in which release occurs from the mold during polymerization of the prepolymer, leaving mold release marks on the lens surface.

Example 2 A manufacturing experiment was conducted under the conditions of Example 1 by changing the timing of tape removal. The results are shown in Table 3.

Margins below [Effects of the Invention] As explained above, the method for manufacturing a synthetic resin lens of the present invention involves positioning two matrix molds facing each other, wrapping tape around these matrix molds to fix them, and By injecting a liquid monomer or liquid prepolymer into the gap between the molds, removing the tape when the monomer or prepolymer reaches a gel-like semi-cured state, and allowing the polymerization to proceed further,
Inconveniences such as mold release do not occur during polymerization, and production yield can be greatly improved.

Furthermore, since shrinkage of the reactants can be tolerated, the S polymerization temperature can be increased and the polymerization time can be shortened.

[Brief explanation of drawings]

1 and 2 are graphs showing the polymerization conditions in Examples of the present invention, with FIG. 1 showing the polymerization conditions of Example 1, and FIG. 2 showing the polymerization conditions of Comparative Example 1, respectively.

Claims (1)

[Claims] Two matrix molds are positioned facing each other, a tape is wound around these matrix molds to fix them, and a liquid monomer or a liquid prepolymer is injected into the gap between the matrix molds and polymerized and cured.
A method for producing a synthetic resin lens, characterized in that the tape is removed from the matrix when the monomer or prepolymer reaches a gel-like semi-cured state, and polymerization is further advanced and completed.