JP2000108219A - Plastic lens manufacturing method - Google Patents

Abstract

(57) [Summary] [Problem] A method for eliminating a bubble and cloudiness inside a plastic lens and a bubble at an outer periphery to obtain a plastic lens excellent in appearance, optical performance, mechanical strength, dyeability, workability, and the like. . A liquid curable compound is injected into a mold formed by sealing the periphery of two glass molds positioned at a predetermined interval with a sealing member, and polymerized and cured to obtain a plastic lens. Before or after injecting the liquid curable compound, the mold is covered with a film-like material, and polymerization curing is performed in that state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a plastic lens by a casting method.

[0002]

2. Description of the Related Art As a method of manufacturing a plastic lens, a casting method, a cutting and polishing method, an injection molding method and the like can be mentioned.
In general, a casting method that can more easily form a plastic lens is used. In the casting molding method, the molding surfaces of two glass molds are opposed to each other at a predetermined interval, and in this state, the raw material monomer is injected into the inner space of the mold produced by sealing the peripheral surface with a sealing member. The mainstream method is to polymerize and cure to form a plastic lens. As the sealing member, a gasket or an adhesive tape obtained by applying an adhesive to a sheet-like substrate is used.

On the other hand, in recent years, the refractive index of plastic lens materials has been increasing, and plastic lenses made of allyl carbonate-based resin, acrylate-based resin, methacrylate-based resin, and thiourethane-based resin are becoming more workable and heat-resistant. Widely used because of its excellent impact resistance. Among them, particularly, thiourethane-based resin composition,
After polymerization and curing, a resin having a refractive index of 1.60 or more can be obtained, and thus many products have been commercialized. However, in this thiourethane resin composition, the polymerization proceeds slowly by mixing the polyisocyanate compound and the polythiol compound, which are the raw materials, so that the isocyanate component reacts with water to generate carbon dioxide gas during the polymerization and foams. easy. This phenomenon is particularly remarkable in the casting method. As a result, bubbles and white turbidity inside the plastic lens and bubbles on the outer peripheral portion are caused, which causes deterioration in appearance, optical performance, mechanical strength, dyeability, processing workability, and the like.

[0004] As a method for solving the above-mentioned problem, the oxygen permeability of the sheet substrate of the pressure-sensitive adhesive tape for fixing the glass mold is set to 1%.
A method of limiting the water vapor permeability to 5 cc / m ² · 24 hr · 0.1 mm or less and the water vapor transmission rate to 10 g / m ² · 24 hr · 0.1 mm or less has been disclosed (Japanese Patent Publication No. 5-64564). Furthermore, a method is disclosed in which a mold into which a raw material is injected is polymerized in an atmosphere having a water content of 3.5 ppm or less (Japanese Patent Laid-Open No. 10-58551).

[0005]

However, although the former method can prevent optical distortion, it has no effect on the generation of bubbles. Furthermore, since the sheet base material of the pressure-sensitive adhesive tape has poor rigidity and lacks the ability to hold a mold, it is not suitable for the casting method and has a problem of high cost. . Further, even when such a sheet base material having a low water vapor transmission rate is used, if the sealing property at the overlapping portion of the film is insufficient, water vapor may enter therefrom. The latter method is not preferable because it requires costly remodeling of mechanical equipment.

Accordingly, the present invention provides a plastic lens excellent in product quality that can use conventional glass molds, adhesive tapes and mechanical equipment as it is in a casting method, and has no bubbles, turbidity, or bubbles on the outer periphery. To provide a manufacturing method for the same.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies in view of the above problems, and as a result, have reached the present invention. That is, in the method for manufacturing a plastic lens of the present invention, a liquid curable compound is injected into a mold formed by sealing the periphery of two glass molds positioned at a predetermined interval with a sealing member. A method of producing a plastic lens by polymerizing and curing, wherein the mold is covered with a film before or after injecting the liquid curable compound, and polymerized and cured in that state.

Further, the present invention is characterized in that the film-like material has a water vapor transmission rate of 10 g / m ² · 24 h · 0.1 mm or less.

[0009] The liquid curable compound mainly comprises a mixture of a polyisocyanate compound and a polythiol compound.

The effect of the present invention can be expected in the range in which the mold is covered with the film-like material in the present invention, as long as the entire mold or at least the adhesive tape surface can be covered.

Specific examples of the film substrate include:
Polyvinylidene chloride, polyvinylidene fluoride, PET,
Examples include PP, PPS, PEN, and polyimide aluminum, which can be selected according to the material of the sealing member. However, in order to prevent the generation of bubbles during the polymerization of the thiourethane-based resin composition, it is preferable to use a film having a water vapor transmission rate of 10 g / m ² · 24 h · 0.1 mm or less regardless of the material of the sealing member. preferable. If it is more than this, bubbles are easily generated.

The thickness of the film is suitably from 5 to 100 μm. If it is 4 μm or less, the workability is poor because it is too thin, and if it is 101 μm or more, it does not conform to the shape of the mold.

As the liquid curable compound in the method for producing a plastic lens of the present invention, it is preferable to use a composition mainly composed of at least one polyisocyanate compound and a polythiol compound.

The polyisocyanate compounds include tolylene diisocyanate, diphenylmethane diisocyanate, polymeric diphenylmethane diisocyanate, tolidine diisocyanate, naphthalene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated diphenylmethane diisocyanate, Methyl xylylene diisocyanate, tolylene diisothiocyanate, diphenylmethane diisothiocyanate, tolidine diisothiocyanate, naphthalene diisothiocyanate, hexamethylene diisothiocyanate, isophorone diisothiocyanate, xylylene diisothiocyanate, 2,5-bis (isocyanate Chill) bicyclo [2,2,1] heptane, 2,6-bis (isocyanatomethyl) bicyclo [2,2,1] heptane, 3,8-bis (isocyanatomethyl) tricyclo [5,2,1,0 ^{2 , 6} ] -decane, 3,9-bis (isocyanatomethyl) tricyclo [5,2,1,0 ^2,6 ] -decane, 4,8-bis (isocyanatomethyl) tricyclo [5,2,1,0 ^{2 , 6} ]
- decane, 4,9-bis (isocyanatomethyl) tricyclo [5,2,1,0 ^2,6] - decane, polyiso and dimer acid diisocyanate (thio) cyanate compound and allophanate-modified products of these compounds, biuret modified And modified isocyanurate, and can be used alone or as a mixture of two or more kinds as necessary.

Further, specific examples of the polythiol compound include the following compounds.

[0016]

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[0017]

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[0018]

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[0019]

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[0020]

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In addition, di (2-mercaptoethyl) ether, 1,2-ethanedithiol, 1,4-butanedithiol, ethylene glycol dithioglycolate, trimethylolpropane tris (thioglycolate), pentaerythritol tetrakis (2- Mercaptoacetate), pentaerythritol tetrakis (3-mercaptopropionate), 1,2-dimercaptobenzene, xylylenedithiol, 4-mercaptomethyl-
3,6-dithio-1,8-octanedithiol is also included.

By reacting these polythiol compounds with a polyisocyanate compound, a sulfur-containing urethane-based plastic lens having a high refractive index and a well-balanced durability such as falling ball strength, heat resistance, dyeability, and weather resistance. Can be obtained. Furthermore, a polythiol compound and a polyol compound can be used in combination.

When casting a plastic lens, the ratio of the polyisocyanate compound to the polythiol compound used is such that the molar ratio of NCO / SH (functional group) is usually 0.5 to 0.5.
It is necessary to carry out in the range of 3.0, preferably 0.5 to 1.5. In addition, internal release agents, chain extenders, crosslinking agents, light stabilizers, ultraviolet absorbers, antioxidants, coloring agents such as disperse dyes, oil-soluble dyes and pigments, bluing agents, reaction catalysts, etc. And a polythiol compound.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited thereto.

(Example 1) Two glass molds whose molding surfaces face each other at a predetermined interval, and in this state, the peripheral surface is adhered to an adhesive tape (a sheet of a biaxially oriented polyester base material having a thickness of 38 μm). 20μm thick silicone adhesive
And coated and fixed to form a mold for manufacturing a plastic lens. 4-mercaptomethyl-
87 g of 3,6-dithio-1,8-octanedithiol,
94 g of m-xylylene diisocyanate, 0.02 g of dibutyltin dilaurate, 0.15 g of an internal release agent, 2-
0.09 g of (5-methyl-2-hydroxyphenyl) benzotriazole was mixed, and a sufficiently stirred monomer was degassed under a vacuum of 5 mmHg or less for 60 minutes.

This monomer was injected into the mold for producing a plastic lens, and the entire mold was covered with a polyvinylidene chloride film (thickness: 20 μm) (a sectional view is shown in FIG. 1). Thereafter, the temperature was maintained at 40 ° C. for 7 hours in a thermostat, and then the temperature was raised from 40 ° C. to 120 ° C. over 10 hours to perform polymerization. After the completion of the polymerization, the system was cooled down to room temperature, and the polyvinylidene chloride film, the adhesive tape and the glass mold were removed to obtain a plastic lens.

Example 2 In a plastic lens manufacturing mold similar to that used in Example 1,
The same monomer as described above was injected, and the entire mold was covered with a polyvinylidene fluoride film (20 μm) (FIG. 1).
Is held in a thermostat at 40 ° C. for 7 hours, and then the temperature is raised from 40 ° C. to 120 ° C. over 10 hours to carry out polymerization.

After the polymerization was completed, the mixture was cooled to room temperature, and the polyvinylidene fluoride film, the adhesive tape and the glass mold were removed to obtain a plastic lens.

Example 3 Two glass molds whose molding surfaces face each other at a predetermined interval are sealed with a gasket (base material: ethylene-vinyl acetate copolymer) in this state. It was stopped and fixed with a clip to make a plastic lens manufacturing mold.

The same monomer as in Example 1 was injected into the mold for producing a plastic lens, and the gasket surface of the mold was coated with a PET adhesive film (a film-like PET base material having a thickness of 38 μm was coated with a silicone-based adhesive to a thickness of 38 μm). 20μ
m) is kept at 40 ° C. for 7 hours in a thermostat, and then
The polymerization was carried out by raising the temperature from 120 ° C. to 120 ° C. over 10 hours. After the polymerization was completed, the mixture was cooled to room temperature, and the PET adhesive film, gasket, and glass mold were removed to obtain a plastic lens.

Comparative Example 1 The same monomer as in Example 1 was injected into the same plastic lens manufacturing mold as in Example 1, and was kept at 40 ° C. for 7 hours in a thermostat.
Polymerization was performed by raising the temperature from 0 ° C. to 120 ° C. over 10 hours. After the completion of the polymerization, the system was cooled to room temperature, the adhesive tape and the glass mold were removed, and a plastic lens was obtained.

Comparative Example 2 The same monomer as in Example 3 was poured into the same plastic lens manufacturing mold as in Example 3, and was kept at 40 ° C. for 7 hours in a thermostatic oven. The temperature was raised to 10 ° C. over 10 hours to carry out polymerization. After the completion of the polymerization, the system was cooled down to room temperature, the gasket and the glass mold were removed, and a plastic lens was obtained.

With respect to the above Examples 1 to 3 and Comparative Examples 1 and 2, 100 superimposed lenses were evaluated according to the following non-defective product standards.

<Non-defective product standard> Bubble: A bubble generated in the center of the lens was visually evaluated, and a non-existent one within 3.0 mm from the lens outer periphery in the center direction was regarded as a non-defective product. Cloudiness: The cloudiness of the lens was evaluated visually and with a projector, and those that were not visible at all were evaluated as good. Chips: Air bubbles generated on the outer periphery of the lens were visually evaluated. Those that did not exist within 3.0 mm from the outer periphery toward the center were regarded as non-defective products.

[0035]

[Table 1]

[0036]

According to the method for producing a plastic lens of the present invention, bubbles and white turbidity inside the plastic lens and bubbles on the outer peripheral portion due to foaming during polymerization can be prevented. As a result, a plastic lens excellent in appearance, optical performance, mechanical strength, dyeability, workability, and the like can be manufactured with high yield. Further, according to the method for manufacturing a plastic lens of the present invention, even when a low-cost tape or gasket having a high water vapor transmission rate is used, a good product can be stably obtained, so that the production cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a plastic lens manufacturing mold whose entire surface is covered with a film-like material according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a plastic lens manufacturing mold in which a sealing member surface is covered with a film-like material in an embodiment of the present invention.

[Explanation of symbols]

 1. Glass mold 2. Sheet base material 3. Adhesive SaD gasket TaD film

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G02B 3/00 G02B 3/00 Z F term (Reference) 4F202 AA31 AA34 AA42 AD08 AH74 AJ06 CA01 CB01 CD16 4F213 AA31 AA34 AA42 AD08 AH74 AJ06 WA02 WA53 WA56 WA87 WB01 WC01 WF01 WF27 4J034 BA02 CA32 CB03 CB04 CB05 CB07 CC08 CC10 CC12 CC61 CC62 CC65 CD04 CD06 CD08 HA01 HA07 HB02 HC03 HC12 HC13 HC17 HC22 HC45 HC46 HC52 HC53 HC61 HC

Claims (3)

[Claims] 1. A liquid curable compound is injected into a mold formed by sealing the periphery of two glass molds positioned at a predetermined interval with a sealing member, and polymerized and cured to form a plastic. A method for producing a plastic lens, comprising: before or after injecting the liquid curable compound, coating the mold with a film-like material and polymerizing and curing the mold in that state. 2. The film-like material has a water vapor transmission rate of 10 g.
^{2. The} method for producing a plastic lens according to claim 1, wherein the thickness is not more than / m ² · 24h · 0.1 mm. 3. The method for producing a plastic lens according to claim 1, wherein the liquid curable compound mainly comprises a mixture of a polyisocyanate compound and a polythiol compound.