JP2000191846A - Resin composition for manufacturing gasket for producing plastic lens, gasket for producing plastic lens using same and plastic lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide resin compositions for manufacturing gaskets for producing plastic lenses which have good workability and good optical properties, gaskets for producing plastic lenses using the same, and plastic lenses. SOLUTION: Resin compositions for manufacturing gaskets for producing plastic lenses comprise 100 pts.wt. ethylene/α-olefin copolymer obtained by using a metallocene catalyst and having a density of 0.89-0.92 g/ml, a melt index of 3-15 g/10 min, and a ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of 2.0-3.5, and 50-300 pts.wt. ethylene/ethyl acrylate copolymer having a melt index of 3-30 g/10 min and an ethyl acrylate content of 13-25 wt.%. Gaskets for producing plastic lenses are manufactured with these compositions. A method for producing plastic lenses comprises casting a liquid monomer or its prepolymer in between two molds separated and matched through a gasket to cure it. Plastic lenses are made by this method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a resin composition for producing a gasket for producing a plastic lens, a gasket for producing a plastic lens using the composition, a method for producing a plastic lens using the gasket, and a plastic lens. About.

[0002]

2. Description of the Related Art Conventionally, in a plastic lens, a liquid monomer as a raw material is injected between two molds separated by a gasket, the temperature is raised to a curing temperature, and the resin is cured, and then the gasket is peeled off. It has been manufactured by a method of removing a molded plastic lens from a mold. At that time, the material of the gasket includes low-density polyethylene by high-pressure radical polymerization, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, soft vinyl chloride resin, ethylene-propylene copolymer, multi-site catalyst Linear ethylene-α-olefin copolymers, metallocene-catalyzed linear ethylene-α-olefin copolymers, and the like.

However, gaskets for manufacturing plastic lenses generally require the following performance. (B) Flexibility Absorbs stress following polymerization shrinkage of the monomer. When the rigidity is high, the lens and the mold do not follow the polymerization shrinkage, peel off during the polymerization, and the lens surface becomes not smooth. (B) Heat resistance When heat-polymerizing a monomer, heat resistance is required.
For example, in the case of diethylene glycol bis-allyl carbonate called CR-39, generally 85 to 95
C., in the case of a urethane monomer, generally 90 to 10
A heat resistance of 0 ° C. is required. If the heat resistance is low, the gasket is deformed during the polymerization, and as a result, a desired lens shape cannot be formed. In addition, the gasket welds the lens, making removal difficult. (C) Solvent resistance No compatibility with monomers and lenses. If the solvent resistance is low, the lens becomes cloudy or the lens and the gasket are in close contact with each other, making it difficult to remove the gasket. (2) Formability If the melt index is extremely low, the work of forming the gasket becomes difficult, and molding is likely to be defective. (E) Cleanability The gasket needs to be clean because it forms the outer periphery of the lens. In that case, as a typical cleaning method,
There are the following methods a) to d). a) Antistatic air method This is the simplest method in which antistatic air is blown onto the gasket surface to remove deposits on the gasket surface. b) Cleaning method using chlorine-based solvent (including CFC-based) The cleaning method is good and the work is easy, but it is difficult to continue this method due to environmental problems. c) Cleaning method using a hydrocarbon-based solvent The cleaning property is slightly inferior to that of a chlorine-based solvent, but it is possible with a long time. Heating is required for drying, and there is a disadvantage that the gasket is deformed. d) Cleaning method with aqueous cleaning agent There is the same drawback as the cleaning method using a hydrocarbon-based solvent in c) above.

In view of the above-mentioned performance requirements for the gasket or the requirements for the gasket manufacturing process, all the plastics which have been conventionally used as gasket materials are examined below. Plastic had some problems. That is, the low-density polyethylene produced by the high-pressure radical polymerization method has a somewhat insufficient flexibility, and the above (a) and (b)
Is not sufficient without satisfying the conditions. Although the ethylene-vinyl acetate copolymer has flexibility, it has a melting point of 90 ° C. or less, and has a strong polar group in the molecule, and therefore does not satisfy the conditions (b) and (c) and is insufficient. In the ethylene-ethyl acrylate copolymer, the content of ethyl acrylate must be increased to nearly 20% in order to have flexibility, but the melting point is lowered (about 92 to 93 ° C.), the heat resistance is deteriorated, and the solvent resistance is lowered. Because of its poor performance, only a monomer having a relatively low polymerization temperature and a low dissolving power (for example, CR-39) can be applied, and it is difficult to use a monomer having a high polymerization temperature and a monomer having a dissolving power. Soft PVC resin is
Since it contains a plasticizer, there is a disadvantage that uneven dyeing of the lens is likely to occur. The ethylene-propylene copolymer has a melting point of 90 ° C. or less, has insufficient heat resistance, and is extremely difficult to use alone. The linear ethylene-α-olefin copolymer with a multi-site catalyst has a melting point of 115 to 1
The temperature is as high as 20 ° C., and the heat resistance is sufficient, but the flexibility is slightly insufficient. In order to provide flexibility, the α-olefin copolymerization ratio must be increased, and the low molecular weight component increases, and as a result, the low molecular weight component bleeds to the surface and becomes sticky. Dust and the like easily adhere and are difficult to remove. Therefore, cleaning with a solvent is indispensable for preventing the lens from being defective, which is not preferable in terms of the environment and work (drying is required and takes time). The metallocene-catalyzed linear ethylene-α-olefin copolymer has a small amount of low molecular weight compounds, but has insufficient flexibility and is insufficient.

Various attempts have been made to improve these disadvantages, for example, a mixture of polyisobutylene and polyethylene (JP-B-43-25830), an ethylene-vinyl acetate copolymer, a polyolefin and an ethylene-vinyl acetate copolymer.
Mixture of propylene copolymers (JP-A-54-387)
3), a mixture with an ethylene-propylene copolymer (US
P3,821,333), an ionomer resin or a resin containing the same as a main component (JP-A-58-194519), and a polyethylene having a specific polymerization degree (JP-A-61-1258).
14), a silicone-containing elastomer (JP-A No. 2-12)
8810), a mixture of an ethylene-α-olefin copolymer rubber and a specific plurality of ethylene-α-olefin copolymers (JP-A-2-185586), a thermoplastic resin containing a polyolefin resin and an olefin copolymer rubber A mixture of an elastomer and an olefin polymer having a specific melting point (JP-A-2-196439), an ethylene copolymer having a specific flexural modulus and a Vicat softening point (JP-A-5-82)
30), an ethylene-α-olefin copolymer having specific physical properties (JP-A-8-176206), an ethylene-α-olefin copolymer polymerized using a metallocene catalyst, and polymerized using a catalyst other than a metallocene catalyst Ethylene-α-
Mixture of olefin copolymers (JP-A-8-30233)
6) have been proposed, but none of them have been satisfactory. As described above, a gasket that satisfies the above-described conditions required as a gasket for producing a plastic lens has not yet been proposed, and therefore, its appearance as soon as possible has been demanded.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method in which two molds are separated by a gasket.
When a liquid monomer or its prepolymer is injected and cured to produce a plastic lens or plate, it has the property of expanding or contracting properly due to the volume expansion of the liquid monomer and the stress accompanying polymerization shrinkage, and the gasket is made of glass. It has the appropriate flexibility to attach or detach from a mold, has high heat resistance because it can be placed in a relatively high temperature heating furnace for long-time curing, and has no compatibility with liquid monomers and plastic lenses A gasket for producing a plastic lens, which has a property of being easy to peel off from a plastic lens without adversely affecting the polymerization reaction, not causing cloudiness in the plastic lens, and having excellent moldability and cleaning properties. The present invention further provides a gasket for manufacturing a plastic lens using the composition. Process for producing a plastic lens using the gasket, and to provide a plastic lens.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have combined various plastics and manufactured gaskets for each of them.
When a plastic lens was manufactured using this, it was found that a gasket made of a combination of two specific types of plastics gave good results. The present invention has been completed based on these findings.

That is, according to the present invention, the density obtained by the metallocene catalyst is 0.89 to 0.93 g / m 2.
1, the melt index is 3 to 15 g / 10 min, and the ratio (Mw) between the weight average molecular weight (Mw) and the number average molecular weight (Mn)
/ Mn) is 100 to 100 parts by weight of an ethylene-α-olefin copolymer having a melt index of 3 to 3;
0 g / 10 min, ethyl acrylate content 13-25
50% by weight of ethylene-ethyl acrylate copolymer
A resin composition for producing a plastic lens production gasket comprising 300 parts by weight, and a plastic lens production gasket produced from the resin composition are provided.

Further, according to the present invention, a method of manufacturing a plastic lens, which comprises injecting a liquid monomer or a prepolymer thereof between two molds separated by the above gasket and curing the same, and A plastic lens made by the method is provided.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The metallocene-catalyzed ethylene-α-olefin copolymer used in the present invention is a copolymer of ethylene and an α-olefin, for example, an α-olefin having 3 to 12 carbon atoms, using a metallocene catalyst.
Specific examples of the α-olefin include propylene, butene-1, hexene-1, 4-methylpentene-1, octene-1, decene-1, dodecene-1, and the like. In the present invention, the metallocene catalyst used in the production of the ethylene-α-olefin copolymer has the same active site (single site) and has high polymerization activity with respect to ethylene. Therefore, the ethylene-α-olefin copolymer produced with a metallocene catalyst has a narrower composition distribution and molecular weight distribution than those produced with a conventional Ziegler-based catalyst or a Phillips-based catalyst, and therefore, has poor mechanical properties. Are better. The metallocene catalyst is also called a single-site catalyst or a Kaminski catalyst from the inventor's name as another name.

As the catalyst component, the following formulas (1) to (1)
The compound represented by (3) can be exemplified. Equation _{(1): (Cp) m} MR n R 'p (1) ( wherein, Cp is unsubstituted or substituted cyclopentadienyl group, M is a transition metal of 4-10 periodic table, R
And R ′ are each independently a halogen atom, a carbon atom of 1
M is 1 to 3, n is 0 to 3, p is 0 to 3, and m + n + p is equal to the oxidation state (valence) of M. The transition metal compound represented by). Equation (2) or _{(2 '): (C 5} R' m) p R "s (C 5 R 'm) MQ 3-p-x) (2) R" s (C 5 R' m) 2 MQ '(2') (wherein C ₅ R ' _m is an unsubstituted or substituted cyclopentadienyl group, wherein R's independently of one another are a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, An alkenyl group, an aryl group, an alkylaryl group, an arylalkyl group or two carbon atoms linked together to form part of a C ₄ -C ₆ ring, wherein R ″ is one or more carbon, germanium , silicon, phosphorus or nitrogen atom, or combinations thereof, these two C _{5 R 'm} ring above by replacing the group bridging them or one C _{5 R'
m} contains a group that is substituted on the _m- ring to bridge M, and when p is 0, x is 1; otherwise, x is always 0; 1 or 2 atoms
0 is an alkyl group, alkenyl group, aryl group, alkylaryl group, arylalkyl group or halogen atom, Q ′ is an alkylidene group having 1 to 20 carbon atoms, s is 0 or 1, and s is 0. And m is 5 and p is 0, 1 or 2, and when s is 1, m is 4 and p is 1. The transition metal compound represented by). The transition metal compounds represented by the above formulas (1), (2) and (2 ′) are described in JP-A-8-134121, JP-T-8-509773, and JP-T-8-510290. The disclosures of these patent publications are incorporated in the present specification by referring to the publications described in the publications. Equation (3):

Embedded image (Wherein M is a metal atom of Groups 3 to 10 of the periodic table or a lanthanoid, Cp is an unsubstituted or substituted cyclopentadienyl group bonded to M in an η5 bond mode, Z is boron or Table 14 elements and, if appropriate, atomic groups containing sulfur or oxygen atoms, said atomic groups having up to 20 atoms other than hydrogen or
p and Z together form a fused ring system, X is independently of each other an anionic ligand or a neutral Lewis base ligand having up to 30 atoms other than hydrogen, and n is 0, 1, 2, 3 or 4 and two less than the valency of M, and Y is an anionic or non-anionic ligand which binds to Z and M, a nitrogen atom, a phosphorus atom, an oxygen atom Or containing a sulfur atom and having up to 20 non-hydrogen atoms or optionally Y and Z together forming a fused ring system. The transition metal compound represented by). The transition metal compound represented by the above formula (3) is described in JP-A-6-306121, JP-A-7-500622, and the like. Is incorporated herein by reference. The metallocene catalyst described above may further contain an activating cocatalyst. As the cocatalyst, aluminoxane having a high or low degree of polymerization, particularly methylaluminoxane, is suitable. Also, so-called modified aluminoxane is suitable as the cocatalyst.

The polymerization of the ethylene-α-olefin copolymer is preferably carried out by a method such as a solution polymerization method, a suspension polymerization method and a gas phase polymerization method. At this time, as general polymerization reaction conditions, the temperature is 0 to 250 ° C., and the pressure is high pressure (50 MPa or more), medium pressure (10 to 50 MPa), or low pressure (normal pressure to 10 MPa). The density of the ethylene-α-olefin copolymer made with the metallocene catalyst used in the present invention needs to be 0.89 to 0.93 g / ml. If the density is less than 0.89 g / ml, the heat resistance is insufficient, and the gasket must be cleaned using a solvent, which is not desirable. On the other hand, if the density exceeds 0.93 g / ml, flexibility is lost, and it is impossible to follow the expansion and contraction of the plastic lens, which is not desirable. Further, the melt index of the ethylene-α-olefin copolymer produced by the metallocene catalyst used in the present invention needs to be 3 to 15 g / 10 minutes. If the melt index is less than 3 g / 10 min, the moldability is poor when the gasket is made by injection molding, while if it exceeds 15 g / 10 min, the heat resistance and the removability are poor, which is not desirable. Further, ethylene-α formed with the metallocene catalyst used in the present invention
-The ratio (Mw / Mn) between the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the olefin copolymer is 2.0 to
It needs to be 3.5. If the Mw / Mn is less than 2.0, the moldability is poor when the gasket is made by injection molding. On the other hand, if the Mw / Mn is more than 3.5, the gasket must be cleaned using a solvent. Absent.

The ethylene-ethyl acrylate copolymer used in the present invention is obtained by polymerizing ethylene and ethyl acrylate by a high-pressure radical polymerization method, and has a melt index of 3 to 30 g / 10 minutes and an ethyl acrylate content of 3 to 30 g / 10 minutes. 13 to 25% by weight. If the melt index is less than 3 g / 10 minutes, when the gasket is made by injection molding, the moldability is poor, a gasket with a smooth surface cannot be obtained, and the flexibility is poor, and it follows the expansion and contraction of the plastic lens. Cannot be desirable.
On the other hand, if it exceeds 30 g / 10 minutes, heat resistance and removability are inferior and undesirable. On the other hand, if the ethyl acrylate content is less than 13% by weight, flexibility, adhesion to glass and plastic lenses, handleability, etc. are deteriorated, while if it exceeds 25% by weight, heat resistance, dimensional stability, Poor sealing performance is not desirable.

The gasket for producing a plastic lens according to the present invention is a gasket made of ethylene-α prepared using the metallocene catalyst.
An ethylene-ethyl acrylate copolymer having the above specific melt index and ethyl acrylate content of 50 to 100 parts by weight of the olefin copolymer;
It is made from the resin composition obtained by blending 300 parts by weight. If the blending amount of the ethylene-ethyl acrylate copolymer is less than 50 parts by weight, the flexibility is insufficient, and the ability to follow the expansion and contraction of the plastic lens is poor. On the other hand, if the blending amount of the ethylene-ethyl acrylate copolymer exceeds 300 parts by weight, heat resistance and solvent resistance deteriorate, which is not desirable.

In the present invention, the molding method of the gasket to be used is not particularly important, and any known molding method can be applied. However, the injection molding method is desirable in terms of productivity, gasket accuracy, and the like. . The form and usage of the gasket are not special and may be any commonly used ones.
This is shown in the perspective view of the figure. The usage will be described with reference to the drawings. As shown in the sectional view of FIG.
Inject the liquid monomer 4 between the molds and 2 and 3,
What is necessary is just to hold | maintain a mold with the clamp 5, and to perform hardening. However, the illustrated gasket is merely an example, and the gasket is not limited thereto. In the present invention, glass is most suitable as the material of the mold to be used. However, the material is not limited thereto, and plastic, metal, ceramic, and the like can be used.
The form of the mold is usually a disk shape, and the surface in contact with the liquid monomer in the cavity has a curved surface required for the lens. The lens produced by the method of the present invention is used in glasses, cameras, microscopes, projectors, OHPs, and the like. The material of the gasket of the present invention may contain an antioxidant, a UV inhibitor, a release agent, a bulking agent, an antistatic agent, a dye, and the like, which are usually added to plastics. In the present invention, other plastics used as gasket plastics in addition to the ethylene copolymer, for example, thermoplastic elastomers, silicone rubber,
Polyisobutylene or the like may be added.

As the liquid monomer used in the present invention, diethylene glycol bis-allyl carbonate, methyl methacrylate, 2,2-bis (4-methacryloxyethoxy-3,5-dibromophenyl) propane, styrene, chlorostyrene, α- Methyl styrene,
Phenyl methacrylate, bromophenyl methacrylate, methoxyphenyl methacrylate, benzyl methacrylate, tribromobenzyl methacrylate, 1-vinylnaphthalene, α-naphthyl methacrylate, allyl cinnamate, bisphenol A-dimethacrylate, 2,
Examples thereof include 3,5,6-tetrachlorobisphenol A-dimethacrylate, O-diallyl phthalate, diallyl isophthalate, diethylene glycol methacrylate, and glycidyl methacrylate. In addition, these liquid monomers can be partially polymerized and used as a liquid prepolymer.

A polymerization initiator such as a peroxide is usually added to these liquid monomers. However, as another method, it is also possible to cure with light or radiation without adding a polymerization initiator. Examples of the polymerization initiator include dis-secondary-butylperoxydicarbonate, diisopropylperoxydicarbonate, bis (4-tert-butylcyclohexyl) peroxydicarbonate, di-3-methoxybutylperoxydicarbonate, and di-2-ethylhexyl. Peroxycarbonate,
Examples include benzoyl peroxide, lauroyl peroxide, azobisisobutylnitrile, acetylcyclohexylsulfonyl peroxide, cumylperoxy neodecanoate, and t-butylperoxypiparate. In the case of producing a urethane-based plastic lens, as a raw material, an isocyanate compound, a polyisocyanate compound, an isothiocyanate compound, a polythiocyanate compound or the like and a hydroxy compound, a mercapto compound, a compound selected from a hydroxy compound having a mercapto group, and the like are used. use. As the catalyst, a Lewis acid, a tertiary amine or the like is usually used.

[0018]

The present invention will be described below in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples.

Example 1 Density 0.90 g / ml, melt index 3.7 g / ml
10 minutes, 100 parts by weight of an ethylene-octene-1 copolymer made with a metallocene catalyst of Mw / Mn = 3.2, ethylene-ethyl acrylate having a melt index of 5.6 g / 10 minutes and an ethyl acrylate content of 18% by weight Using a resin composition containing 230 parts by weight of the copolymer as a raw material, an annular T-shaped gasket having an inner diameter of 65 mm was produced by injection molding. Blowing of antistatic air at a pressure of 3 kg for the purpose of removing extraneous matter such as dust on the surface of this gasket
This was performed at f / cm ² for 5 seconds. Next, the spherical power -4.0
In order to obtain a prescription having 0 deopters and a center thickness of 2.0 mm, two glass molds were prepared and preliminarily washed to remove deposits on the surface. The above-mentioned glass mold and gasket assembling clamp were attached to prepare a mold. On the other hand, a plastic lens material (urethane-based monomer) was prepared as follows. That is, 100 parts by weight of m-xylylene diisocyanate, pentaerythritol tetrakis-3-mercaptopropionate 14
2 parts by weight, 6 parts by weight of di-n-butyl phosphate, 0.25 parts by weight of dibutyltin dilaurate, and 0.5 parts by weight of 2- (2′-hydroxy-5′-t-octylphenyl) benzotriazole as an ultraviolet absorber Were sufficiently stirred and degassed under vacuum. Next, in order to remove foreign substances in the mixture, the mixture was passed through a polypropylene filter having a filtration accuracy of 1.0 μm, and the filtrate was poured into the mold. Thereafter, the temperature was raised from 25 ° C. to 100 ° C. over 20 hours, the gasket and the clamp were once removed, and the temperature was held again at 120 ° C. for 2 hours to carry out polymerization. A wedge was driven between the mold and the lens to separate them, and the obtained lens was annealed at 120 ° C. for 1 hour.
The properties of the obtained polyurethane-based plastic lens and the properties of the gasket were evaluated in the following manner, and all were satisfactory. The results are shown in Tables 1 and 2.

[0020]

[Table 1]

[0021]

[Table 2]

1. External view of the lens Using an illuminating device that illuminates a fluorescent lamp, visually check the following 1)
It was observed whether or not items 3) were satisfied. (JIS T
7313 4.3) 1) Transparency (transparency), 2) Irregularity is not easily recognized on the surface, 3) Foreign matter is not easily recognized inside the lens, 2. Optical performance of lens Satisfy item 3.1 Optical performance of focus spectacle lens for vision correction according to JIS T7313. 3. Releasability of gasket Whether the lens and gasket can be easily peeled when separated from each other. Gasket moldability Whether automatic molding can be easily performed by injection molding method,

Example 2 Density 0.925 g / ml, melt index 12.3
g / 10 minutes, 100 parts by weight of an ethylene-hexene-1 copolymer prepared with a metallocene catalyst having an Mw / Mn of 3.4, an ethylene-ethyl acrylate having a melt index of 25 g / 10 minutes and an ethyl acrylate content of 24% by weight. An experiment was conducted in the same manner as in Example 1 except that a resin composition containing 60 parts by weight of a copolymer was used as a raw material, but good results were obtained as shown in Table 1.

Example 3 The same resin composition as in Example 1 was used as a raw material and had an inner diameter of 65 m.
m annular T-shaped gasket was manufactured by injection molding. The surface of the gasket is sprayed with antistatic air at a pressure of 3 kgf / cm ² for the purpose of removing extraneous matter such as dust at a pressure of 3 kgf / cm ² .
Seconds. Next, two glass molds were prepared in order to obtain a prescription having a spherical power of −4.00 deopters and a center thickness of 2.0 mm, and were washed in advance to remove the deposits on the surface. The above-mentioned glass mold and gasket were assembled and a clamp was attached to prepare a mold. Next, a liquid obtained by adding 100 parts by weight of diethylene glycol bisallyl carbonate as a plastic raw material and 3 parts by weight of diisopropyl pyroxycarbonate as a polymerization initiator and mixing the mixture was passed through a polypropylene filter having a filtration accuracy of 1.0 μm. Thereafter, the filtrate was injected into the mold.
Thereafter, the temperature was raised from 40 ° C. to 90 ° C. over 24 hours to carry out polymerization. After removing the gasket and the clamp, a wedge was driven between the mold and the lens to separate them, and the obtained lens was annealed at 120 ° C. for 1 hour. As shown in Table 1, good results were obtained for the characteristics of the obtained plastic lens and the characteristics of the gasket.

Comparative Example 1 An experiment was performed in the same manner as in Example 1 except that the density of the ethylene-octene-1 copolymer produced with the metallocene catalyst was changed to 0.89 g / ml.

Comparative Example 2 An experiment was performed in the same manner as in Example 1 except that the density of the ethylene-octene-1 copolymer produced with the metallocene catalyst was changed to 0.932 g / ml.

Comparative Example 3 In Example 1, the ethylene-octene-1 copolymer prepared with a metallocene catalyst had a melt index of 2.5.
The same experiment as in Example 1 was performed except that g / 10 minutes was used instead.

Comparative Example 4 In Example 1, the melt index of the ethylene-octene-1 copolymer prepared with a metallocene catalyst was 18 g.
The same experiment as in Example 1 was performed except that the time was changed to / 10 minutes.

Comparative Example 5 An experiment was performed in the same manner as in Example 1 except that the Mw / Mn value of the ethylene-octene-1 copolymer prepared with the metallocene catalyst was changed to 1.9.

Comparative Example 6 An experiment was performed in the same manner as in Example 1 except that the Mw / Mn value of the ethylene-octene-1 copolymer prepared with the metallocene catalyst was changed to 3.7.

Comparative Example 7 The same experiment as in Example 1 was performed, except that the melt index of the ethylene-ethyl acrylate copolymer was changed to 2.7 g / 10 minutes.

Comparative Example 8 The same experiment as in Example 1 was performed, except that the melt index of the ethylene-ethyl acrylate copolymer was changed to 30 g / 10 minutes.

Comparative Example 9 The same experiment as in Example 1 was performed, except that the ethyl acrylate content of the ethylene-ethyl acrylate copolymer was changed to 10% by weight.

Comparative Example 10 The same experiment as in Example 1 was performed except that the ethyl acrylate content of the ethylene-ethyl acrylate copolymer was changed to 28% by weight.

Comparative Example 11 An experiment was conducted in the same manner as in Example 1 except that the amount of the ethylene-ethyl acrylate copolymer to be added to the resin composition was changed to 40 parts by weight.

Comparative Example 12 An experiment was conducted in the same manner as in Example 1 except that the amount of the ethylene-ethyl acrylate copolymer compounded in the resin composition was changed to 330 parts by weight.

[0037]

According to the present invention, a plastic composition is prepared by mixing a specific ethylene-α-olefin copolymer prepared with a metallocene catalyst and a specific ethylene-ethyl acrylate copolymer at a specific compounding ratio. Because we manufacture gaskets for lenses, this gasket
It follows the expansion and contraction of the plastic lens during polymerization well, has the appropriate flexibility when attaching and removing the gasket to and from the glass mold, and can be easily worked. It has heat resistance enough to withstand, can form a desired lens shape, and is easily removed without welding the gasket to the lens. In addition, since the gasket is not compatible with the monomer and the lens, there is no clouding of the lens, and there is no adhesion between the lens and the gasket, and the gasket is easily removed. It can be easily done by the prevention air method. Gasket molding is also easy, molding time is reduced,
The surface of the molded product is also beautifully finished, which has the effect of obtaining a plastic lens with a clean surface.

[Brief description of the drawings]

FIG. 1 is a perspective view of a gasket.

FIG. 2 is a cross-sectional view of a state where a mold is held by a clamp.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gasket 2, 3 Mold 4 Liquid monomer 5 Clamp

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yuji Hoshi 2-7-5 Nakaochiai, Shinjuku-ku, Tokyo Inside HOYA Corporation (72) Inventor Yuichiro Sakuma 3-11 Wakabadai, Nagareyama-shi, Chiba (72) Invention Person Akio Goto 4-21-17 Highland, Yokosuka City, Kanagawa Prefecture (72) Inventor Toshio Kogure 18-9 Sodegahama, Hiratsuka City, Kanagawa Prefecture F-term (reference) 4F202 AA04E AA08 AA21 AA21E AH74 AJ03 AM32 CA01 4J002 BB05W BB07X BB15W GP01

Claims (4)

[Claims] The density obtained by the metallocene catalyst is 0.89 to 0.93 g / ml and the melt index is 3
100 parts by weight of an ethylene-α-olefin copolymer having a weight-average molecular weight (Mw) and a number-average molecular weight (Mn) ratio (Mw / Mn) of 2.0 to 3.5; A resin composition for making a gasket for producing a plastic lens, comprising 50 to 300 parts by weight of an ethylene-ethyl acrylate copolymer having an index of 3 to 30 g / 10 min and an ethyl acrylate content of 13 to 25% by weight. 2. A gasket for producing a plastic lens made of the resin composition according to claim 1. 3. A method for manufacturing a plastic lens, comprising: injecting a liquid monomer or a prepolymer thereof between two molds separated by a gasket according to claim 2 and curing the same. 4. A plastic lens produced by the method according to claim 3.