JP2002248636A - Method for manufacturing plastic lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a plastic lens capable of suppressing the generation of tape wrinkles in a tape molding method for sealing the gap between molds by a pressure-sensitive adhesive tape. SOLUTION: Two molds 11 and 12 are moved along the inner surface of the pressure-sensitive adhesive tape from the position, which is fixed in a mold assembling process, in a curing process so as to narrow the interval between the molds to lower the holding force or tackiness of the pressure-sensitive adhesive tape 13, for example, at the time of polymerization.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a plastic lens, and more particularly, to a method for producing a plastic lens for molding a plastic lens by a cast polymerization method.

[0002]

2. Description of the Related Art When producing a plastic lens having excellent optical performance, a casting polymerization method is usually used. As a casting polymerization method, a tape molding method in which a gap between molding dies is sealed with an adhesive tape is known (JP-A-11-99527).
JP, JP-A-6-346034, JP-B-5-6
No. 4,564, JP-B-3-8246, etc.). This tape molding method will be described with reference to FIG.

[0003] As shown in FIG. 3A, a lens casting polymerization mold 300 is assembled in a molding die assembly process. An adhesive tape 303 is wound around the side surfaces of the two glass molds 301 and 302 arranged at a predetermined interval slightly more than one round, and the gap between the molds 301 and 302 is sealed with the adhesive tape 303. As a result, the positions of the molds 301 and 302 are fixed to each other with the adhesive tape 303, and a lens casting having a cavity 304 for molding a lens surrounded by the two molds 301 and 302 and the adhesive tape 303. A polymerization mold 300 is prepared.

[0004] Next, as shown in FIG. 3 (b), in an injection step, the adhesive tape 303 is peeled off until there is a gap for injecting it into the cavity, and the raw material composition 310 is injected into the cavity 303 from this gap. The gap is sealed again with the adhesive tape 303.

Next, as shown in FIG. 3C, the raw material composition 310 in the cavity 304 is polymerized and cured by ultraviolet light or heat to obtain a plastic lens 311.

Thereafter, the adhesive tape 303 is peeled off, the molds 301 and 302 are separated from the plastic lens 311 and a predetermined plastic lens can be taken out.

However, during polymerization and curing, the raw material composition 3
10 shrinks in volume. In particular, a recent raw material composition for a high refractive index has a large polymerization shrinkage. Therefore, the mold 30
Adhesive tape 3
3, the adhesive tape 303 is crushed in the thickness direction of the cavity 304, and a tape wrinkle 306 as shown in FIG. The generation of the tape wrinkles 306 becomes more conspicuous as the edge of the side of the plastic lens 311 is thicker. And this tape wrinkle 3
Reference numeral 06 denotes a plastic lens 31 formed by polymerization and curing.
The image is directly transferred to the edge of the outer periphery. Since the tape wrinkles 306 generated on the edge of the plastic lens outer periphery impair the appearance and accuracy of the outer diameter, the outer peripheral portion is removed by cutting or grinding, and an outer peripheral shaping step for improving the appearance is provided.

[0008]

For this reason, the outer diameters of the molds 301 and 302 used in the present casting polymerization method are about 5 mm larger than the finished outer diameter of the plastic lens. As a result, the raw material shaved by the outer peripheral shaping is wasted, leading to an increase in manufacturing cost,
There is a problem of generating plastic waste.

In addition, a step called an outer peripheral shaping step is required, and there is a problem that the yield is reduced due to an increase in the number of steps and occurrence of defects such as scratches in the outer peripheral shaping step.

[0010] These problems are caused by the occurrence of tape wrinkles in the tape molding method, and will be solved if the occurrence of tape wrinkles can be suppressed.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method of manufacturing a plastic lens capable of suppressing the occurrence of tape wrinkles in a tape molding method.

[0012]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventor has found that the adhesive force of the adhesive tape is reduced in the polymerization step of the tape molding method from that in the mold assembling step. As a result, it was found that the stress of volume shrinkage due to the polymerization of the raw material composition exceeded the adhesive strength of the adhesive tape, and the mold was drawn toward the cavity and moved on the inner surface of the adhesive tape. As a result, the amount of polymerization shrinkage becomes substantially equal to the amount of movement of the molding die, and the amount of polymerization shrinkage can be absorbed by the movement of the molding die. Therefore, deformation of the adhesive tape can be suppressed, and occurrence of tape wrinkles can be suppressed.

In order to reduce the adhesive strength of the adhesive tape, the adhesive strength can be reduced by, for example, irradiation with ultraviolet light or heating.

If the holding power of the pressure-sensitive adhesive tape according to JIS Z0237 is 120 minutes or less at the temperature at which the amount of polymerization shrinkage of the raw material composition per unit time is the maximum, when the polymerization shrinkage is most intense, The shrinkage stress overcomes the adhesive strength between the mold and the adhesive tape, so that the mold can be displaced from the inner surface of the adhesive tape.

Therefore, according to the first aspect of the present invention, an adhesive tape is wrapped around the side surfaces of two molding dies which are arranged opposite to each other at a predetermined interval, and these molding dies are fixed with the adhesive tape.
A molding die assembly step of forming a cavity for molding a lens surrounded by the individual molds and the adhesive tape, an injection step of injecting a raw material composition into the cavity, and curing the raw material composition to form a plastic lens In the method for producing a plastic lens having a curing step to obtain, in the curing step, one or both of the two molds move the inner surface of the adhesive tape from a position fixed in the mold assembly step. To provide a method for manufacturing a plastic lens, characterized in that the distance between the plastic lenses is reduced.

According to a second aspect of the present invention, in the method of manufacturing a plastic lens according to the first aspect, the moving amount of the mold is substantially equal to the amount of polymerization shrinkage of the raw material composition. A manufacturing method is provided.

According to a third aspect of the present invention, there is provided a method of manufacturing a plastic lens according to the first aspect, wherein the adhesive force of the adhesive tape is reduced during the curing step. I do.

According to a fourth aspect of the present invention, there is provided a method of manufacturing a plastic lens according to any one of the first to third aspects,
A method for producing a plastic lens, characterized in that a holding force according to JIS Z0237 of the pressure-sensitive adhesive tape is 120 minutes or less at a temperature at which a polymerization shrinkage amount per unit time of the raw material composition is a maximum.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the method for manufacturing a plastic lens according to the present invention will be described below, but the present invention is not limited to the following embodiments.

As described above, the plastic lens manufacturing method of the present invention is a method of manufacturing a plastic lens in which tape wrinkles are suppressed by making the mold move on the inner surface of the adhesive tape in the polymerization step in the tape molding method. can do.

The mold can be moved on the inner surface of the pressure-sensitive adhesive tape by, for example, lowering the holding force of the pressure-sensitive adhesive tape in a polymerization step.

That is, as a pressure-sensitive adhesive tape, when assembling a lens casting polymerization mold, it has a holding force capable of firmly fixing the molding die, and the temperature at which the amount of polymerization shrinkage of the raw material composition per unit time in the polymerization step is the maximum. In this case, it is preferable that the holding force is reduced to such an extent that the mold is separated from the adhesive tape by the shrinkage stress of the raw material composition.

Specifically, as the adhesive tape used in the method for producing a plastic lens of the present invention, for example, a heat-peelable tape can be used. The heat-peelable adhesive tape is, for example, 2
The holding power specified in JIS Z0237 of the adhesive tape at 3 ± 2 ° C is 10 minutes or more, particularly 30 minutes or more, and optimally 1 minute or more.
Preferably, it is longer than 440 minutes. If the holding power at room temperature is lower than this, the shape of the cavity formed around the mold and the adhesive tape changes before the raw material composition is injected, and the thickness and the thickness of the plastic lens formed by polymerization and curing are reduced. The position of the optical center may deviate from the target.

At a temperature at which the amount of polymerization shrinkage per unit time of the raw material composition is maximum, the JIS
Holding force according to Z0237 is 120 minutes or less, especially 100
Minutes or less, optimally 60 minutes or less. 0
Minutes are fine. If the holding power is large, it is difficult for the mold to move on the inner surface of the pressure-sensitive adhesive tape when the raw material composition is being polymerized and shrunk. In some cases, it cannot be suppressed.

In general, the holding power of the pressure-sensitive adhesive tape decreases with increasing temperature. However, the holding power of a normally used adhesive tape emphasizes the adhesive strength and has a holding power of more than 1440 minutes even at 130 ° C. With such an adhesive tape, the displacement of the contact surface of the mold does not occur due to polymerization shrinkage in the polymerization process, so that the force for narrowing the gap between the molds is transmitted to the adhesive tape, and the adhesive tape has a thickness of the cavity. 3C, the tape wrinkles 306 as shown in FIG. 3C are generated.

Incidentally, the test method for the holding power of the adhesive tape according to JIS Z0237 is 23 ± 2 ° C., and the relative humidity is 65 ± 5.
% Test locations are specified. Take three test pieces of 25 mm width and about 150 mm length from the adhesive tape sample, affix them so that the area of 25 x 25 mm is in contact with one end of the cleaned test plate, and fasten one end of the test plate with a clasp. The test piece shall be hung vertically, a weight of the specified weight shall be attached to the test piece, and a load shall be applied for a specified time.
Measure the distance shifted in mm or measure the time for the tape to fall from the test plate. Therefore, the unit of the holding force is mm or time. In this specification, the weight of the weight attached to the test piece is 1 kg.

The measurement of the holding force at the temperature when the amount of shrinkage per unit time is the maximum is specified in accordance with JIS Z0237 standard, from pretreatment of the sample, collection of the test piece, sticking of the test piece, and crimping of the test piece. The test is performed at 23 ± 2 ° C. as described above, and the test is performed at an arbitrary temperature from the time when the test piece is left at the test temperature until the end of the test. The measurement of the drop time in the test of the holding force is performed up to 1440 minutes, and when the sample does not fall, the measurement is terminated and the holding force is expressed as more than 1440 minutes.

The temperature at which the amount of polymerization shrinkage per unit time of the raw material composition is maximum varies greatly depending on the components of the plastic raw material, the composition ratio thereof, the type and amount of the catalyst, the heating temperature pattern, or the wavelength and intensity of ultraviolet irradiation. .

In the graph shown in FIG. 2, the solid line is an example of the heating temperature pattern, and the broken line indicates the relative change in the amount of polymerization shrinkage. The heating temperature pattern is, for example,
10 to 10 hours, from temperature to 100 to 130 ° C 3 to 7
Time, maintain the temperature for 1 to 3 hours,
Generally, the pattern is cooled to room temperature over a period of time, and a total polymerization time of 15 to 20 hours is required.

The pattern of change in the amount of polymerization shrinkage varies greatly depending on the raw material composition. For example,
At around 0 ° C., the polymerization shrinkage becomes maximum, and
The polymerization shrinkage becomes maximum around 0 ° C.
Around 0 ° C., the polymerization shrinkage becomes maximum. Therefore, it is preferable to previously measure the temperature at which the amount of shrinkage of the raw material composition per unit time is maximum.

In the pressure-sensitive adhesive tape, a pressure-sensitive adhesive layer is formed on a tape base material. Examples of the tape base material include polyolefins such as polyethylene and polypropylene, polyvinyl chlorides such as polyvinyl chloride and polyvinylidene chloride, polyesters such as polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate, polyamides, polyimides and polycarbonates. And the like. Acrylic, rubber, silicone, etc. are used as the adhesive.

The thickness of the tape base material is required to be 10 μm or more, preferably 20 μm or more, because it is necessary to secure the molding die sufficiently in the molding die assembling process and to support the sliding of the molding die in the polymerization process. Is preferably 30 μm or more, and the maximum thickness is about 2000 μm.

In the present invention, it is also possible to use a pressure-sensitive adhesive tape having a re-peelable pressure-sensitive adhesive layer, which usually has a sufficient adhesive strength, and is cured by irradiation with ultraviolet rays or the like to reduce the adhesive strength. For example, the initial adhesive strength is 18 of JIS Z0237.
0 ° peel strength, 1000 g / 25 mm or more, especially 1
500g / 25mm or more, adhesive strength after UV irradiation is 10
It is preferably 0 g / 25 mm or less, particularly preferably 50 g / 25 mm or less.

Such adhesive properties can be obtained, for example, by using an adhesive containing an ultraviolet polymerizable compound composed of a urethane acrylate oligomer.

By using such a re-peelable adhesive tape, when assembling the lens casting polymerization mold, it has an adhesive force capable of firmly fixing the mold, and the adhesive force of the adhesive tape is irradiated by ultraviolet rays in the polymerization process. And the mold can be peeled off from the adhesive tape. This makes it possible to move the inner surface of the pressure-sensitive adhesive tape during polymerization of the mold, thereby suppressing tape wrinkles.

A method of manufacturing a plastic lens by a tape molding method using such an adhesive tape will be described.

The obtained plastic lens includes:
Both sides are transferred by the mold, both sides are transferred to the final optical surface by transfer of the mold, and one side is transferred to the final optical surface by the mold, and the opposite surface is shaped by subsequent polishing etc. There is a slightly thick semi-finished lens made.

First, as shown in FIG. 1A, a lens casting polymerization mold 10 is manufactured in a molding die assembly step. For example, a first molding die 11 for forming a convex surface made of glass and a second molding die 11 for forming a concave surface.
The mold 12 is prepared. The outer diameter of these molds 11 and 12 may be the same as the finished outer diameter of the plastic lens. In a state where these molds 11 and 12 are opposed to each other with a predetermined gap, an adhesive tape 13 is wound around the side surfaces of these molds 11 and 12 slightly more than one turn, and these molds are fixed with the adhesive tape. , Molds 11, 12
By closing the gap therebetween, a cavity 14 for molding a lens surrounded by the two molds 11 and 12 and the adhesive tape 13 is formed. The adhesive tape 13 used at this time is the above-mentioned heat-peelable type or re-peelable type. When a heat-peelable pressure-sensitive adhesive tape is used, a material having the above-described holding power at a temperature at which the amount of polymerization shrinkage per unit time of the raw material composition to be injected into the cavity 14 is maximum is selected.

Next, as shown in FIG. 1 (b), in the pouring step, the adhesive tape 13 is peeled off until a gap is opened in which the cavity 14 can be poured, and the raw material composition 20 is poured into the cavity 14 from this gap. Then, the gap is sealed again with the adhesive tape 13.

The raw material composition is not particularly limited. For example, diethylene glycol bisallyl carbonate (C
R-39). In particular, the recent one for high refractive index has a large polymerization shrinkage and is expensive, so that the method for producing a plastic lens of the present invention has a great effect of saving the raw material composition. Examples of the raw material composition for a high refractive index include those mainly composed of a polymerizable monomer composed mainly of a polyisocyanate having two or more isocyanate groups and a compound having two or more active hydrogens. can do.

Examples of the polyisocyanate having two or more isocyanate groups constituting the polymerizable monomer include m-xylylene diisocyanate, p-xylylene diisocyanate, tetrachloro-m-xylylene diisocyanate, Hydrogenated xylylene diisocyanate, hydrogenated diphenylmethane diisocyanate, tetramethyl xylylene diisocyanate, 2,5-bis (isocyanatomethyl) 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, polyisocyanate compounds such as dimer acid diisocyanate and allophanate-modified products of these compounds, 1,3 Screw (α, α-
Dimethyl isocyanatomethyl) benzene, 1,4-bis (α, α-dimethylisocyanatomethyl) benzene, hexamethylene diisocyanate, isophorone diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, polymeric diphenylmethane diisocyanate Nato, tolidine diisocyanate, naphthalene diisocyanate, 4,4'-diphenylmethane diisocyanate, a biuretation reaction product of hexamethylene diisocyanate, an adduct product of hexamethylene diisocyanate and trimethylolpropane, 4,4 '-Dicyclohexylmethane diisocyanate, modified isocyanurate, and the like, and these compounds can be used alone or in combination of two or more. Among these polyisocyanates, xylylene diisocyanate is preferred.

The compound having two or more active hydrogens constituting the polymerizable monomer is, for example, a polyol having two or more hydroxyl groups, a polythiol having two or more thiol groups, or a hydroxyl group in one molecule. Compounds each having one or more thiol groups can be mentioned.

Examples of the polyol include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, butylene glycol, neopentyl glycol, glycerin, trimethylolethane, trimethylolpropane, butanetriol,
1,2-methylglucoside, pentaerythritol,
Dipentaerythritol, tripentaerythritol,
Sorbitol, erythritol, threitol, ribitol, arabinitol, xylitol, allitol, mannitol, dorsitol, iditol, glycol,
Inositol, hexanetriol, triglycerol, diglyperol, triethylene glycol, polyethylene glycol, tris (2-hydroxyethyl) isocyanurate, cyclobutanediol, cyclopentanediol, cyclohexanediol, cycloheptanediol, cyclooctanediol, cyclohexanedimethanol, hydroxy Propylcyclohexanol,
Tricyclo [5,2,1,0,2,6] decane-dimethanol, bicyclo [4,3,0] -nonanediol, dicyclohexanediol, tricyclo [5,3,1,
1] dodecanediol, bicyclo [4,3,0] nonanedimethanol, tricyclo [5,3,1,1] dodecane-diethanol, hydroxypropyltricyclo [5
3,1,1] dodecanol, spiro [3,4] octanediol, butylcyclohexanediol, 1,1′-
Aliphatic polyols such as bicyclohexylidenediol, cyclohexanetriol, maltitol, lactitol, dihydroxynaphthalene, trihydroxynaphthalene, tetrahydroxynaphthalene, dihydroxybenzene, benzenetriol, biphenyltetraol, pyrogallol, (hydroxynaphthyl) pyrogallol, trihydroxy Aromatic polyols such as phenanthrene, bisphenol A, bisphenol F, xylylene glycol, tetrabromobisphenol A, di- (2-hydroxyethyl) sulfide, 1,2-bis- (2-hydroxyethylmercapto) ethane, bis (2 -Hydroxyethyl) disulfide, 1,4-dithiane-2,5-
Diol, bis (2,3-dihydroxypropyl) sulfide, tetrakis (4-hydroxy-2-thiabutyl) methane, bis (4-hydroxyphenyl) sulfone (trade name: bisphenol S), tetrabromobisphenol S, tetramethylbisphenol S, Examples of the polyol include a sulfur atom-containing polyol such as 4,4'-thiobis (6-tert-butyl-3-methylphenol) and 1,3-bis (2-hydroxyethylthioethyl) -cyclohexane.

The polythiol is not particularly limited. For example, 4-mercaptomethyl-3,6-dithio-1,8-octanedithiol represented by the following formula (1) and pentane represented by the following formula (2) Erythritol tetrakis (3-mercaptopropionate) and tetrathiol represented by the following general formula (3) can be exemplified.

[0045]

Embedded image Specific examples of the tetrathiol represented by this general formula (3) include, for example, compounds (A) to (A) having the following structural formulas:
(G) can be mentioned.

[0046]

Embedded image Other polythiols include, for example, di (2-mercaptoethyl) ether, 1,2-ethanedithiol,
1,4-butanedithiol, ethylene glycol dithioglycolate, trimethylolpropane tris (thioglycolate), pentaerythritol tetrakis (2-
Mercaptoacetate), dipentaerythritol hexakis (3-mercaptopropionate), dipentaerythritol hexakis (2-mercaptoacetate), 1,2-dimercaptobenzene, 4-methyl-
1,2-dimercaptobenzene, 3,6-dichloro-
1,2-dimercaptobenzene, 3,4,5,6-tetrachloro-1,2-dimercaptobenzene, O-xylylenedithiol, m-xylylenedithiol, p-xylylenedithiol, and 1,3 5-tris (3-mercaptopropyl) isocyanurate and the like.

Examples of the compound having one or more hydroxyl groups and one or more thiol groups in one molecule include 2-mercaptoethanol, 3-mercapto-1,2-propanediol, glycerin di (mercaptoacetate),
Hydroxy-4-mercaptocyclohexane, 2,4-
Dimercaptophenol, 2-mercaptohydroquinone, 4-mercaptophenol, 1,3-dimercapto-2-propanol, 2,3-dimercapto-1-propanol, 1,2-dimercapto-1,3-butanediol, pentaerythritol tris (3-mercaptopropionate), pentaerythritol mono (3-mercaptopropionate), pentaerythritol bis (3-mercaptopropionate), pentaerythritol tris (thioglycolate), pentaerythritol pentakis (3-mercapto) Propionate), hydroxymethyl-tris (mercaptoethylthiomethyl)
Methane, 1-hydroxyethylthio-3-mercaptoethylthiobenzene, 4-hydroxy-4′-mercaptodiphenylsulfone, 2- (2-mercaptoethylthio) ethanol, dihydroxyethylsulfide mono (3-mercaptopropionate), Dimercaptoethane mono (sulfylate), hydroxyethylthiomethyl tris (mercaptoethylthio) methane, and the like.

The mixing ratio of the polyisocyanate compound and the active hydrogen is such that the ratio of the isocyanate group (NCO) to the active hydrogen (H) is NCO / H (molar ratio) = 0.5-3.
0, particularly preferably in the range of 0.5 to 1.5.

The polymerization catalyst is not particularly limited, but is preferably a tertiary amine, a tertiary phosphine, or a Lewis acid. Particularly, a combined catalyst of a tertiary amine and a Lewis acid or a combined catalyst of a tertiary phosphine and a Lewis acid is preferable. preferable. These combined catalysts form a complex and have a long pot life.

The amount of the polymerization catalyst used is generally in the range of 0.0005 to 5% by weight based on the polymerizable monomer.

Next, as shown in FIG. 1C, a curing step of curing the raw material composition 20 in the cavity 14 is performed. The thermosetting raw material composition 20 is heated in a heating temperature pattern as shown in FIG. 2, for example. The raw material composition 20 is polymerized by heating to cause polymerization shrinkage. When the polymerization shrinkage is most severe, the holding force of the heat-peelable pressure-sensitive adhesive tape 13 is reduced. In addition, the adhesive force of the re-peelable adhesive tape 13 is reduced by irradiating ultraviolet rays during polymerization.

As a result of the decrease in the holding force and the adhesive force of the adhesive tape 13, the stress caused by the polymerization shrinkage of the raw material composition 20 in the cavity 14 and the weight of the upper mold mainly due to its own weight are fixed in the mold assembly process. From the position shown by the broken line in FIG. 1C, the inner surface of the adhesive tape 13 is slid and descends to approach the lower mold. The amount of movement of the mold at this time is substantially equal to the amount of polymerization shrinkage of the raw material composition 20.

Thus, the volume shrinkage of the raw material composition 20 is absorbed by the movement of the molds 11 and 12, and the pressure-sensitive adhesive tape 1
3 can be prevented from being deformed. The shape of the undeformed adhesive tape 13 is transferred to the side surface of the obtained plastic lens 30, resulting in a shape with good appearance.
Therefore, the outer diameter of the molds 11 and 12 may be the same as the finished outer diameter of the plastic lens. This eliminates the waste of the 5 mm outer peripheral portion conventionally cut in the outer peripheral shaping step. In the case of a lens having a thick outer periphery, the raw material composition can be saved by more than 10%. There is also an advantage that the outer peripheral shaping step is not required.

Active energy ray-curable raw material composition 20
In the curing, the polymer is rapidly polymerized and cured by irradiating ultraviolet rays. At that time, the adhesive force of the adhesive tape 13 is reduced by using the re-peelable adhesive tape 13. Effects such as cost saving and omission of the outer peripheral shaping step can be obtained.

[0055]

<Example 1> The adhesive tape used had a tape base material of polyethylene terephthalate having a width of 25 mm and a thickness of 38 μm, and the thickness of the adhesive layer was 37 μm. The holding power using a 1 kg weight is more than 1440 minutes at a test temperature of 23 ° C., and the test temperature is 70 ° C.
Was 30 minutes.

As a glass mold, a glass mold in which the first mold 11 and the second mold 12 are individually designed to prepare a (-) 10.00 diopter lens having an outer diameter of 75 mm is prepared. did.

As a raw material composition, 103 g of m-xylylene diisocyanate was used as a polyisocyanate compound.
0.01 g of a polymerization catalyst, dimethyltin dichloride, 0.15 g of an internal mold release agent, 0.2 g of an ultraviolet absorber 2- (2-hydroxy-5-methylphenyl) -2H-benzotriazole, and a polymerization catalyst of N, N-dimethylcyclohexyl The amine was mixed in the order of 0.01 g and stirred sufficiently for about 30 minutes. Thereafter, the three types of tetrafunctional mercapto compounds represented by the above structural formulas (A), (B), and (C) (the mixing ratio of the components A, B, and C is A / B / C in molar ratio). = 85/5
/ 10) 100 g was mixed and sufficiently stirred for about 30 minutes, and then degassed under a vacuum of 5 mmHg for 60 minutes to prepare a raw material composition.

It has been confirmed that the temperature of the raw material composition when the amount of polymerization shrinkage per unit time is the maximum is 70 ° C.

The two prepared glass molds were held at necessary intervals, and the prepared adhesive tape 13 was wound around the side of the mold a little more than one round. Thereafter, the adhesive tape 13 was peeled off until there was a gap where the adhesive tape 13 could be injected, and the raw material composition prepared was injected into the cavity 14 from this gap.

The raw material composition is polymerized in a heating furnace in which the temperature is raised from 30 ° C. to 40 ° C. for 4 hours and from 40 ° C. to 120 ° C. for 7 hours, and after cooling, the molding die and the adhesive tape are removed. I got a lens.

Molding 100 plastic lenses,
The appearance of wrinkles on the outer edge was evaluated. The criteria for the evaluation are: lenses without wrinkles ······ lenses with partial wrinkles ··· lenses with wrinkles all around ··· × × Stratified.

Table 1 shows the results.

Comparative Example 1 The adhesive tape used had a tape base material of polyethylene terephthalate having a width of 25 mm and a thickness of 38 μm, and the adhesive layer had a thickness of 27 μm. The holding power using a 1 kg weight is more than 1440 minutes at a test temperature of 23 ° C., and the test temperature is 70 ° C.
Was 139 minutes.

A plastic lens was obtained using the same mold and raw material composition as in Example 1, except that the adhesive tape was different, under the same polymerization conditions.

In the same manner as in Example 1, 100 plastic lenses were molded, and the occurrence of wrinkles on the outer edge was evaluated. The results are also shown in Table 1.

Comparative Example 2 The pressure-sensitive adhesive tape used had a tape base material of polyethylene terephthalate having a width of 25 mm and a thickness of 38 μm, and the pressure-sensitive adhesive layer had a thickness of 39 μm. The holding power using a 1 kg weight is more than 1440 minutes at a test temperature of 23 ° C., and the test temperature is 70 ° C.
Was 1440 minutes.

A plastic lens was obtained under the same polymerization conditions using the same mold and raw material composition as in Example 1 except that the adhesive tape was different.

In the same manner as in Example 1, 100 plastic lenses were molded, and the occurrence of wrinkles on the outer edge was evaluated. The results are also shown in Table 1.

Example 2 The pressure-sensitive adhesive tape used had a tape base material of polyethylene terephthalate having a width of 25 mm and a thickness of 38 μm, and the pressure-sensitive adhesive layer had a thickness of 28 μm. The holding power using a 1 kg weight is more than 1440 minutes at a test temperature of 23 ° C.
At 24 ° C., it was 24 minutes.

As the raw material composition, 4-mercaptomethyl-3,6-dithio-1,8 was used as a polythiol compound.
-40 g of octanedithiol, 0.06 g of dimethyltin dichloride as a polymerization catalyst, 0.15 g of an internal mold release agent,
2- (2-hydroxy-5-ter) as an ultraviolet absorber
0.1 g of (t-octylphenyl) -2H-benzotriazole and 0.04 g of a polymerization catalyst N, N-dimethylcyclohexylamine were mixed in this order, and sufficiently stirred for about 30 minutes. Thereafter, 60 g of hydrogenated diphenylmethane diisocyanate was mixed as a polyisocyanate compound,
After sufficiently stirring for about 1 minute, degassing was performed under a vacuum of 5 mmHg for 60 minutes to prepare a raw material composition.

It has been confirmed that the temperature at which the polymerization shrinkage per unit time of the raw material composition is maximum is 120 ° C.

A glass mold was prepared in the same manner as in Example 1, and the raw material composition was poured in the same procedure as in Example 1, and the raw material composition was cooled from 30 ° C. to 40 ° C. for 5 hours at 40 ° C. The polymerization was carried out in a heating furnace in which the temperature was raised from 400 ° C. to 120 ° C. over 4 hours. After cooling, the mold and the adhesive tape were removed to obtain a plastic lens.

In the same manner as in Example 1, 100 plastic lenses were molded, and the occurrence of wrinkles on the outer edge was evaluated. The results are also shown in Table 1.

Comparative Example 3 The adhesive tape used had a tape base material of polyethylene terephthalate having a width of 25 mm and a thickness of 38 μm, and the adhesive layer had a thickness of 28 μm. The holding power using a 1 kg weight is more than 1440 minutes at a test temperature of 23 ° C.
At ℃, it was 158 minutes.

A plastic lens was obtained under the same polymerization conditions using the same mold and raw material composition as in Example 2 except that the adhesive tape was different.

In the same manner as in Example 1, 100 plastic lenses were molded, and the occurrence of wrinkles on the outer edge was evaluated. The results are also shown in Table 1.

Comparative Example 4 The pressure-sensitive adhesive tape used had a tape base material of polyethylene terephthalate having a width of 25 mm and a thickness of 38 μm, and the thickness of the pressure-sensitive adhesive layer was 30 μm. The holding power using a 1 kg weight is more than 1440 minutes at a test temperature of 23 ° C.
It was more than 1440 minutes even at ° C.

A plastic lens was obtained using the same mold and raw material composition as in Example 2 except that the adhesive tape was different, under the same polymerization conditions.

In the same manner as in Example 1, 100 plastic lenses were molded, and the occurrence of wrinkles on the outer edge was evaluated. The results are also shown in Table 1.

[0080]

[Table 1]

From the results shown in Table 1, it is recognized that tape wrinkling can be suppressed by using an adhesive tape having a holding force at a temperature at which the polymerization shrinkage during the polymerization of the raw material composition is maximum is 120 minutes or less. .

[0082]

According to the method of manufacturing a plastic lens of the present invention, it is possible to suppress the occurrence of tape wrinkles on the side of the plastic lens obtained by the tape molding method, thereby saving the raw material composition and the number of steps. .

[Brief description of the drawings]

FIG. 1 is a flowchart showing steps of a method for manufacturing a plastic lens of the present invention.

FIG. 2 is a graph showing a heating temperature pattern and an amount of polymerization shrinkage.

FIG. 3 is a flowchart showing steps of a conventional plastic lens manufacturing method.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 lens casting polymerization die 11 first molding die 12 second molding die 13 adhesive tape 14 cavity 20 raw material composition 30 plastic lens

Continued on the front page (72) Inventor Yoshio Sano 3-3-5 Yamato, Suwa-shi, Nagano F-term in Seiko Epson Corporation (reference) 4F202 AH74 AJ03 AM32 AR20 CA01 CB01 CC10 CD30 CK41 CK90 4F204 AH74 EA03 EA04 EF01 EF27 EK17 EK22 EK24

Claims (4)

[Claims] An adhesive tape is wrapped around the side surfaces of two molding dies which are arranged opposite to each other at a predetermined interval, and these molding dies are fixed with the adhesive tape, and are surrounded by the two molding dies and the adhesive tape. A method for producing a plastic lens, comprising: a mold assembling step of forming a cavity for molding a molded lens; an injection step of injecting a raw material composition into the cavity; and a curing step of curing the raw material composition to obtain a plastic lens. In the curing step, one or both of the two molding dies move the inner surface of the adhesive tape from a position fixed in the molding die assembling step to reduce the distance between each other. Manufacturing method of plastic lens. 2. The method for manufacturing a plastic lens according to claim 1, wherein the amount of movement of the mold is substantially equal to the amount of polymerization shrinkage of the raw material composition. 3. The method of manufacturing a plastic lens according to claim 1, wherein during the curing step, the adhesive force of the adhesive tape is reduced. 4. The method for producing a plastic lens according to claim 1, wherein the adhesive tape has a holding force according to JIS Z0237, and the amount of polymerization shrinkage per unit time of the raw material composition is maximum. At a temperature of 120 minutes or less.