JP3479512B2 - Resin composition for producing plastic lens molding mold gasket, plastic lens molding mold gasket, and method for producing plastic lens using the same - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a resin composition for producing a plastic lens molding die gasket, a plastic lens molding die gasket, and a method for producing a plastic lens using the same.

[0002]

2. Description of the Related Art Generally, a plastic lens is a lens molding die (also called a molding mold or simply a mold) made of glass or metal, and a gasket (also called a spacer) made of a soft resin by an injection molding method. Will be)
It is manufactured by injecting and polymerizing a lens polymerization raw material into a plastic lens molding mold (which may be simply referred to as a mold in the present specification) consisting of and (polymerization by casting). Conventionally, diethylene glycol bisallyl carbonate has been widely used as a polymerization raw material for plastic lenses, but in recent years, the demand for a plastic lens having a higher refractive index or a lower specific gravity has increased, and a polymerization raw material for lenses has such characteristics. Are being replaced by aromatic, acrylate, methacrylate or thiourethane based monomers capable of providing plastic lenses having

By the way, from the technical and economical viewpoint, the gasket in which the polymerization raw material for plastic lenses is polymerized has flexibility, heat resistance, air and / or
Or water washability (hereinafter also referred to as air / water washability),
And properties such as injection moldability are required. If it has flexibility, the gasket can absorb the stress by the shrinkage of the polymerization raw material / polymer of the lens that occurs during casting polymerization, and if the heat resistance is sufficient, casting of the polymerization raw material for lens Even if the polymerization is carried out at a high temperature, the plastic lens having the desired shape cannot be obtained due to the deformation of the gasket, the gasket does not fuse to the plastic lens, and if the air / water cleaning property is good. This is because it is possible to avoid the problem of discarding the cleaning liquid such as the solvent. Further, the melt mass flow rate is 3 to 30 g / 10.
Min, the Vicat softening temperature is 45 to 70 ° C., the Shore hardness A is 85 or more, the Shore hardness B is 25 or more, and the stiffness is 35 to 45 MPa, the gasket is preferably manufactured by the injection molding method. You can

Gaskets having such characteristics are currently manufactured by injection molding a soft vinyl chloride resin, ethylene-vinyl acetate (EVA) resin, ethylene-alkyl acrylate (EAA) copolymer or the like. , When aromatic, acrylate, methacrylate or thiourethane type monomer is used as the raw material for plastic lens polymerization, low molecular weight fractions and additives in the gasket resin elute during the polymerization. As a result, clouding (white turbidity) or striae (optical distortion of the lens) may occur in the molded plastic lens.

In order to reduce the fogging and striae of this plastic lens, for example, Japanese Patent Laid-Open No. 6-339938 proposes to use a thermoplastic polyurethane elastomer when manufacturing a gasket. But,
When a thermoplastic polyurethane elastomer is used, the heat shrinkability of the produced gasket is poor, so the stress absorption during cast polymerization is insufficient, and because the heat resistance is poor, the gasket is deformed and melts with the plastic lens. In addition to the problem of adhesion, the non-heat-resistant component in the polyurethane elastomer may move to the lens, so that the fog problem may still occur.

[0006]

The object of the present invention is to mold a plastic while maintaining the properties of conventional plastic lens molding mold gaskets such as flexibility, heat resistance, air / water cleaning property, and injection moldability. It is an object of the present invention to provide a resin composition for producing a plastic lens mold casting gasket that does not cause fogging or striae on the lens. Another object of the invention is to provide a plastic lens mold gasket made from such a resin composition. Still another object of the present invention is to provide a method for manufacturing a plastic lens using the plastic lens molding die gasket.

[0007]

The present inventors have made a resin composition for producing a gasket, which comprises an ethylene-α-olefin copolymer having a low low molecular weight fraction and a narrow molecular weight distribution, and a styrene thermoplastic elastomer. When a gasket is manufactured using a material, it has good flexibility, heat resistance, air / water washability, and injection moldability, and as a polymerization raw material for plastic lenses, aromatic, acrylate, methacrylate or It was found that even if a thiourethane-based monomer is used, the obtained plastic lens does not have cloudiness or striae.

That is, the present invention relates to a resin composition for producing a plastic lens mold casting gasket: (A) The density is 0.89 to 0.93 g / cm ³ , and the melt mass flow rate is ³ to 30 g / 10. Ethylene having a ratio (Mw / Mn) of weight average molecular weight (Mw) to number average molecular weight (Mn) of 2.0 to 3.5.
α-olefin copolymer; (B) styrene-based thermoplastic elastomer; and (C) melt mass flow rate of 3 to 30 g / 10 minutes, and alkyl acrylate content of 10 to 25.
The ethylene-alkyl acrylate copolymer, which is the weight%, is (A) :( B) :( C) = 100: 5 to 50: 0 to 7.
There is provided a resin composition comprising 0 weight ratio. In a preferred embodiment, the resin composition further comprises (D) zeolite (A) :( B) :( C) :( D) = 100:
It is included in a weight ratio of 5 to 5: 0 to 70: 0.05 to 5.

The present invention also provides a plastic lens mold casting gasket made from such a resin composition. The present invention further provides a method for producing a plastic lens, which comprises injecting a liquid containing a polymerization raw material for a plastic lens into a plastic lens molding mold comprising the plastic lens molding mold gasket described above; There is provided a process comprising polymerizing a raw material under conditions sufficient for its polymerization. In a preferred embodiment, the method comprises subjecting the plastic lens mold casting gasket to an air wash and / or a water wash prior to injecting the liquid comprising the plastic lens polymerisation raw material into the plastic lens mold. Become.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The first aspect of the present invention comprises at least (A) an ethylene-α-olefin copolymer and (B) a styrene-based thermoplastic elastomer,
Further, it is a resin composition for producing a plastic lens mold casting gasket, which can further contain (C) ethylene-alkyl acrylate copolymer, (D) zeolite and other components.

(A) Ethylene-α-olefin Copolymer The ethylene-α-olefin copolymer used in the present invention is a copolymer of ethylene and α-olefin.
It may be an alternating copolymer, a random copolymer, or a block copolymer. Specific examples of the α-olefin include alkenes having 3 to 12 carbon atoms, and specific examples include propylene, butene-1, and hexene-.
1,4-methylpentene-1, octene-1, decene-
1, dodecene-1 and the like.

This ethylene-α-olefin copolymer has the following properties when measured according to JIS K 6922:
0.89 to 0.93 g / cm ³ , preferably 0.89 to
It has a density of 0.92 g / cm ³ . Density 0.89g
If it is less than / cm ³ , the copolymer will be sticky because it contains many low molecular weight fractions, and the copolymers will agglomerate during injection molding. The uniformity deteriorates and the heat resistance of the gasket itself decreases, and when a plastic lens is manufactured using such a gasket, the plastic lens obtained by polymerization adheres to the gasket or the gasket melts. This makes it difficult to remove the finished lens.
On the other hand, when the density exceeds 0.93 g / cm ³ , the flexibility of the gasket becomes insufficient, and striae start to appear in the molded plastic lens.

This ethylene-α-olefin copolymer has a content of 3 to 30 g / 10 minutes, preferably 4 to 15 g, when measured at 190 ° C. according to JIS K 6922.
It also has a melt mass flow rate of / 10 minutes. When the melt mass flow rate is less than 3 g / 10 minutes, when a gasket is produced from the resin composition by an injection molding method, the resin composition does not flow uniformly into the mold, resulting in deterioration of injection moldability. On the other hand, when it exceeds 30 g / 10 minutes, the resin composition becomes too soft and the heat resistance and the removability of the gasket are deteriorated.

Further, the ethylene-α-olefin copolymer has a Mw / Mn of 2.0 to 3.5, preferably 2.0 to 3.0. These Mw and Mn are measured by a size exclusion chromatography method, respectively. M
When w / Mn is less than 2.0, injection moldability at the time of manufacturing a gasket begins to deteriorate, while when it exceeds 3.5, clouding may occur in a plastic lens molded by the manufactured gasket. is there. Further, if it exceeds 3.5, the low molecular weight fraction in the ethylene-α-olefin copolymer increases, which gives the gasket adhesiveness during gasket molding. Therefore, it is necessary to wash the gasket with a solvent after gasket molding. Is generated, which is not preferable. Mw /
When Mn is the above value, the ethylene-α-olefin copolymer has a narrow molecular weight distribution and a uniform composition.

Such an ethylene-α-olefin copolymer can be prepared by a method such as a solution polymerization method, a suspension polymerization method, a slurry polymerization method or a gas phase polymerization method in the presence of a metallocene catalyst. ~ 250 ℃ temperature and high pressure (50 MPa
Ultra), medium pressure (10 to 50 MPa) or low pressure (normal pressure to 1)
It can be manufactured at any pressure (less than 0 MPa). Here, the metallocene-based catalyst is a single-site catalyst because the active sites are of the same type (single site).
As another name, it is also called a Kaminsky catalyst from the inventor's name, and includes, for example, one composed of a transition metal compound having a substituted cyclopentadienyl ring. Specific metallocene catalysts are disclosed in JP-A-8-134121, JP-A-8-509773, JP-A-8-510290, JP-A-6-306121 or JP-A-7-121.
It is described in Japanese Patent Publication No. 500622. The metallocene-based catalyst may further include an activating cocatalyst. As the co-catalyst, an aluminoxane having a high degree of polymerization or a low degree of polymerization, particularly methylaluminoxane is preferable. So-called modified aluminoxane is also suitable as a cocatalyst. Further, a commercially available ethylene-α-olefin copolymer can also be used. For example, from Dow Chemical to PT
-Ethylene-octene under the trade names of 1145 and 8200
1 copolymer is available.

The shape of the ethylene-α-olefin copolymer thus obtained is powdery with an average particle size of less than 0.02 mm, granular with an average particle size of 0.02 to 2.0 mm,
Although it may be in the form of pellets having an average particle size of 2.0 to 7.0 mm, the average particle size of 2.0 to 7.
A pellet having a diameter of 0 mm is preferable. Ethylene-α-
The olefin copolymer may be present alone or in admixture of two or more in the resin composition for producing a plastic lens molding template gasket of the present invention.

(B) Styrenic Thermoplastic Elastomer The styrenic thermoplastic elastomer used in the present invention is a copolymer of styrene and mainly diene. Specifically, it has a polystyrene (s) phase at both end phases, and polybutadiene (b), polyisoprene (i) as a rubber intermediate phase, ethylene butylene (eb) which is a hydrogenation type polyolefin, or ethylene propylene (ep). ) And the like, and more specifically,
s-bs, si-s, s-eb-s, s-ep-s
The block copolymer of can be mentioned. In addition to these, a random copolymer hydrogenated styrene-butadiene rubber (hydrogenated s-br) can also be mentioned.

In a preferred embodiment, a hydrogenated styrene-butadiene rubber (hydrogenated s-br) random copolymer and styrene-isoprene-styrene (s-i-) are used.
s) Block copolymers are used. This styrene-based thermoplastic elastomer has
It is preferably 10 g / 10 minutes or more when measured at 230 ° C. according to JIS K6922. But,
Since the styrene-based thermoplastic elastomer is blended to give flexibility to the ethylene-α-olefin copolymer which is the base resin of the present invention, even if its melt mass fluorate is less than 10 g / 10 minutes. It can be compensated by using a high melt mass flow rate ethylene-α-olefin copolymer.

Such styrene thermoplastic elastomers include 8600HSRB available from Nippon Synthetic Rubber as Dynaron series, Kraton D-1112 available from Shell Japan as Kraton D and Kraton G series, and Tuftec H from Asahi Kasei. Series and Tuftec M series available as Tuftec H1031.

In the resin composition for producing a plastic lens mold casting gasket of the present invention, one or more styrene type thermoplastic elastomers may be blended. The blending amount of the elastomer is 5 to 50 parts by weight, preferably 1 part by weight based on 100 parts by weight of the ethylene-α-olefin copolymer.
It is 5 to 35 parts by weight, more preferably 20 to 30 parts by weight. If the blending amount of the styrene-based thermoplastic elastomer is less than 5 parts by weight, the flexibility of the gasket produced from the resin composition of the present invention becomes insufficient, and striae occur in the plastic lens molded with the gasket. It is not preferable because it will start. On the other hand, if it exceeds 50 parts by weight,
The resin composition becomes too soft, the heat resistance and the removability of the produced gasket are lowered, and the styrene-based thermoplastic elastomer is expensive, so that the overall cost is increased.

(C) Ethylene-alkyl acrylate
Ethylene is used in the polymer present invention - the alkyl acrylate copolymer is a copolymer of ethylene and alkyl acrylate. It may be an alternating copolymer, a random copolymer, or a block copolymer. Specific examples of the alkyl acrylate include alkyl acrylates having 1 to 4 carbon atoms such as methyl acrylate, ethyl acrylate, propyl acrylate, and butyl acrylate.

This ethylene-alkyl acrylate copolymer is 3 to 30 g / 10 minutes, preferably 3 to 1 when measured at 190 ° C. according to JIS K 6922.
It has a melt mass flow rate of 5 g / 10 min. When the melt mass flow rate is less than 3 g / 10 minutes, the resin composition is not uniformly injected into the mold when the gasket is manufactured from the resin composition by the injection molding method, and the injection moldability is deteriorated. On the other hand, when it exceeds 30 g / 10 minutes, the resin composition becomes too soft, and the heat resistance and the removability of the produced gasket deteriorate.

The content of alkyl acrylate in this ethylene-alkyl acrylate copolymer is 10 to 25.
It is necessary that the content is wt%, preferably 15 to 20 wt%. When the content of the alkyl acrylate is less than 10% by weight, the flexibility of the produced gasket decreases,
Further, when the gasket is manufactured by the injection molding method, the resin composition is not uniformly injected into the mold, and the injection moldability is deteriorated. On the other hand, when it exceeds 25% by weight, the resin composition becomes too soft and the heat resistance and the removability of the gasket deteriorate. Further, since the alkyl acrylate contains a relatively large amount of a low molecular weight fraction, when the amount is large in the ethylene-alkyl acrylate copolymer, it may cause clouding or striae. A preferred ethylene-alkyl acrylate copolymer is an ethylene-ethyl acrylate (EEA) copolymer.

The ethylene-alkyl acrylate copolymer having such characteristics is usually produced by a high pressure radical polymerization method. Also, a commercially available ethylene-alkyl acrylate copolymer can be used. For example, ethylene-available from Nippon Unicar under the trade name NUC-6170SD
Examples include ethyl acrylate copolymer.

The shape of the ethylene-alkyl acrylate copolymer thus obtained is powdery with an average particle size of less than 0.02 mm, granular with an average particle size of 0.02 to 2.0 mm, or an average particle size of 2.0 to 2.0. Although it may be in the form of pellets having a size of 7.0 mm, pellets having an average particle size of 2.0 to 7.0 mm are preferable from the viewpoint of easy handling.

The ethylene-alkyl acrylate copolymer may be present in the resin composition of the present invention alone or in admixture of two or more. The blending amount is 0 to 100 parts by weight of the ethylene-α-olefin copolymer.
70 parts by weight, preferably 30 to 65 parts by weight, more preferably 40 to 60 parts by weight.

Even if the ethylene-alkyl acrylate copolymer is not contained in the resin composition for producing a plastic lens mold casting gasket of the present invention, the produced gasket has good flexibility, heat resistance and air resistance. It has water washability and injection moldability, and it does not cause clouding or striae on the plastic lens molded using the gasket, but by blending with an ethylene-alkyl acrylate copolymer, it can be used for plastic lenses. There is an advantage that it is easy to take out the plastic lens after casting polymerization of the polymerization raw material. In addition, cheap ethylene-
Economical effects can be obtained by replacing a part of the expensive styrene-based thermoplastic elastomer with an alkyl acrylate copolymer. On the other hand, if the blending amount of the ethylene-ethyl acrylate copolymer exceeds 70 parts by weight with respect to 100 parts by weight of the ethylene-α-olefin copolymer, clouding and striae will start to occur in the plastic lens, which is not preferable.

(D) Zeolite The zeolite used in the present invention is a crystalline aluminosilicate containing alkali and alkaline earth metals, and may be natural or synthetic. In the present invention, zeolite chemically synthesized from sodium silicate, aluminum hydroxide or caustic soda can be used. Specifically, it is a synthetic zeolite available from Tosoh under the trade name of Toyo Builder Powder, and Eihin Kasei C
An example is a synthetic zeolite available under the trade name of S-100. It is preferable that the average particle size is 0.5 to 5.0 μm and the bulk density is 0.1 to 0.7 g / cm ³ .

Zeolite is used for producing a plastic lens mold casting gasket by, for example, preventing pelletized resin composition from agglomerating at the time of injection molding the gasket and by its molecular adsorption ability, that is, molecular trapping ability by the zeolite crystal structure. It has an effect of adsorbing a low molecular weight fraction contained in the resin composition for use and further preventing the plastic lens molded by the gasket from being clouded or striae. Further, since the odor caused by the low molecular weight fraction generated from the gasket is captured, the working environment is remarkably improved. The amount of zeolite compounded is 0.05 to 5 parts by weight, preferably 0.5 to 2 parts by weight, based on 100 parts by weight of the ethylene-α-olefin copolymer. When the amount of zeolite added exceeds 5 parts by weight, the flow characteristics of the resin composition deteriorate, and the injection moldability during the production of a gasket deteriorates. Moreover, when the plastic lens molded by the gasket is taken out, it may be scratched.

Other Components In the resin composition for producing a plastic lens molding mold gasket of the present invention, an antioxidant, an ultraviolet absorber, a light stabilizer, a release agent, and a weight-increasing agent, which are usually added to plastics as required. Agents, antistatic agents, dyes, pigments, fillers and the like can be added. These may be blended as they are, or may be blended as a so-called masterbatch prepared from these additives and an ethylene resin. This ethylene-based resin is not limited to the ethylene-α-olefin copolymer and ethylene-alkyl acrylate copolymer used in the present invention, but is also a high pressure low density ethylene homopolymer, medium density polyethylene, high density polyethylene, linear chain. Low density polyethylene or the like may be used. Therefore, in the present invention, a small amount of another ethylene-based resin can be blended within a range that does not impair the effects of the present invention. For example, 0.3-
It is also possible to prepare a masterbatch using an ethylene-based resin containing 1.5% by weight of an additive, and add this to the resin composition for producing a gasket up to about 10% by weight.

Examples of antioxidants that can be added to the resin composition of the present invention include phenol-based, sulfur-based, and phosphorus-based antioxidants, which may be used alone or in combination of two or more. The antioxidant content is 100
0.00 parts by weight based on the resin composition for manufacturing gaskets
It is about 5 to 1 part by weight.

In a preferred embodiment, the resin composition for producing a plastic lens mold casting gasket of the present invention comprises (A)
A density of 0.89 to 0.92 g / cm ³ , a melt mass flow rate of 4 to 15 g / 10 min, and M
An ethylene-α-olefin copolymer having a w / Mn of 2.0 to 3.0, (B) hydrogenated styrene-butadiene rubber (hydrogenated s-br) random copolymer or styrene-isoprene-styrene ( s-i-s) block copolymer, and (C) melt mass flow rate of 3 to 15
g / 10 min, the alkyl acrylate content is 15
˜20% by weight of ethylene-alkyl acrylate copolymer, (A) :( B) :( C) = 100: 15-3
It is included in a weight ratio of 5:30 to 65.

In a more preferred embodiment, the resin composition for producing a gasket of the present invention has a (A) density of 0.89 to 0.9.
2 g / cm ³ , melt mass flow rate 4 to 15 g /
10 minutes and an ethylene-octene-1 copolymer having Mw / Mn of 2.0 to 3.0, (B) a hydrogenated styrene butadiene rubber having a melt mass fluorate of 10 g / 10 minutes or more (hydrogenation s -Br) a random copolymer or a styrene-isoprene-styrene (si-s) block copolymer, and (C) a melt mass flow rate of 3 to 15 g / 10 minutes, and an ethyl acrylate content of 15 ˜20 wt% ethylene-ethyl acrylate copolymer, (A) :( B) :( C) = 100: 2
It is a resin composition which contains in a weight ratio of 0-30: 40-60, and also contains (D) zeolite in a weight ratio of 0.05-5.

The resin composition for producing a plastic lens mold casting gasket of the present invention is prepared by mixing a predetermined amount of each component with a V-blender, a ribbon blender, a Henschel mixer or a tumbler mixer, and then an extruder, a kneader or a Banbury mixer. Etc., for example, 100 to 130
It is produced by melt-kneading at ℃. Then, it is granulated to an average particle size of about 2 to 7 mm using a strand cutter or the like. The respective components may be blended at once or may be divided.

The second aspect of the present invention is a plastic lens mold casting gasket manufactured from the above resin composition. The gasket of the present invention is manufactured by a known injection molding method after melting the granulated product of the above resin composition. Generally, the melting temperature of injection molding is 130 to 180 ° C. The shape of the gasket is not particularly limited, but is usually annular or cylindrical. FIG. 1 shows an annular gasket.
After the molding, the cooled gasket is taken out from the gasket molding mold, and the opening is closed with a pair of molding dies from above and below to form a plastic lens molding mold. It should be noted that this does not mean that the plastic lens molding mold used in the present invention is composed of only the gasket and the molding die, and other parts, for example, the injection port for the polymerization raw material may be provided. Good. FIG. 2 shows a plastic lens molding mold formed by combining a gasket and a molding die.

A third aspect of the present invention is a method for producing a plastic lens, wherein a liquid containing a polymerization raw material for a plastic lens is placed in a plastic lens molding die containing the plastic lens molding die gasket. Injecting; and polymerizing the polymerization raw material under conditions sufficient for the polymerization. In a preferred embodiment, the method comprises subjecting the plastic lens mold casting gasket to an air wash and / or a water wash prior to injecting the liquid comprising the plastic lens polymerisation raw material into the plastic lens mold. Become.

Polymerization raw materials for producing plastic lenses used in this method include diethylene glycol bis-
Allyl-based monomers such as allyl carbonate, o-diallyl phthalate, diallyl isophthalate and allyl cinnamate; methyl methacrylate, 2,2-bis (4-
Methacryloxyethoxy-3,5-dibromophenyl)
Propane, phenyl methacrylate, bromophenyl methacrylate, methoxyphenyl methacrylate, benzyl methacrylate, tribromobenzyl methacrylate, α-naphthyl methacrylate, bisphenol A-
(Meth) acrylate monomers such as dimethacrylate, 2,3,5,6-tetrachlorobisphenol A-dimethacrylate, diethylene glycol dimethacrylate and glycidyl methacrylate; styrene, chlorostyrene, α-methylstyrene and 1-vinyl. An aromatic monomer such as naphthalene can be used. These polymerization raw materials for producing a monomer-based lens may be partially polymerized and used as a prepolymer.

A polymerization initiator such as a peroxide is usually added to these monomer-based polymerization raw materials for producing a lens, but it is also possible to polymerize with light or radiation without adding a polymerization initiator. As the polymerization initiator, di-sec-butylperoxydicarbonate, diisopropylperoxydicarbonate, bis (4-tert.-butylcyclohexyl) peroxydicarbonate, di-3-methoxybutylperoxydicarbonate, di- Peroxide polymerization initiators such as 2-ethylhexyl peroxycarbonate, benzoyl peroxide, lauroyl peroxide, acetylcyclohexyl sulfonyl peroxide, cumyl peroxy neodecanoate, tert-butyl peroxy piperarate; and Examples thereof include azo-based polymerization initiators such as azobisisobutylnitrile.

Further, as a polymerization raw material for a plastic lens, any one of an isocyanate compound, a polyisocyanate compound, an isothiocyanate compound, a polythioisocyanate compound and the like, and a hydroxy compound, a mercapto compound, or a compound having a hydroxy group and a mercapto group. By using a compound system selected from any of the above, a urethane plastic lens can be produced. In this case, the catalyst usually includes Lewis acid and tertiary amine. If necessary, known additives such as an ultraviolet absorber and a light stabilizer can be appropriately added to the polymerization raw material for plastic lenses.

The above liquid polymerization raw materials for plastic lenses, or a mixture of two or more thereof, is poured into a plastic lens molding mold comprising the cleaned gasket of the present invention and a glass or metal molding die. To do. After the injection, polymerization is carried out by heating or irradiation with ultraviolet rays. The polymerization conditions for the plastic lens of the present invention are appropriately determined depending on the monomers to be polymerized, the polymerization initiator added, and the like. For example, there is a method of gradually raising the temperature from around room temperature to 120 ° C. for polymerization, a method of gelating at a constant temperature to some extent and then raising the temperature to perform polymerization. After the polymerization, cool to room temperature, take out the plastic lens together with the gasket, and then separate the plastic lens from the gasket.

For cleaning the above plastic lens molding mold, the gasket has been used so far with methylene chloride or HC.
In some cases, it was necessary to wash with a solvent such as FC-141b, but in the present invention, 3 kgf / cm ²
Only by blowing antistatic air of a certain pressure for a few seconds to a few minutes, or by ultrasonic cleaning in water or warm water that has been filtered with a filter having a filtration accuracy of 20 μm or less, finally it becomes cloudy or striae. And a plastic lens free of foreign matter is obtained. Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

[0042]

[Examples] Measurement of physical properties Density: Measured according to JIS K 6922. Melt mass flow rate: Measured according to JIS K 6922. The measurement temperature is 190 ° C. unless otherwise specified. Vicat softening temperature: Measured according to JIS K 6924. Hardness Shore A: Measured according to JIS K 6760. Hardness Shore D: Measured according to JIS K 6760. Stiffness: Performed in accordance with JIS K 6760.

Evaluation Method Evaluation of Resin Composition for Gasket Manufacture Granularity of Resin Composition: Those capable of being granulated by melt-kneading with a twin-screw extruder and then strand-cutting were regarded as acceptable. If the resin composition cannot be granulated, the flexibility of the resin composition is too high and the rigidity as a gasket is insufficient. Injection moldability: The ones that could be easily molded into a gasket by injection molding were passed, and those that were not were rejected.

Evaluation of Molded Plastic Lens Removability of plastic lens: Those which could easily separate the plastic lens from the gasket after cast polymerization were passed, and those which were not easy to separate from the gasket were rejected. Appearance of plastic lens: JIS T7313 4.
In accordance with 3, the following items were visually evaluated using an illuminating device using a fluorescent lamp as a light source. A) Whether it is cloudy and transparent b) Whether irregularities are not easily recognized on the surface and there is no striae

Raw materials used in Examples and Comparative Examples and their abbreviations are as follows. Raw material (A) ethylene-α-olefin copolymer (A-1): ethylene-octene-1 copolymer for gasket manufacturing resin composition ; density 0.902 g / cm ³ ; melt mass flow rate 7 g /
10 minutes; Mw / Mn = 2.3; Trade name: PT-114
5, Dow Chemical Co. (polymerized by metallocene catalyst) (A-2): ethylene-octene-1 copolymer; density 0.87 g / cm ³ ; melt mass flow rate 5 g / 1
0 minutes; Mw / Mn = 2.6; trade name: 8200, manufactured by Dow Chemical Co. (polymerized with a metallocene catalyst) (A-3): ethylene-butene-1 copolymer; density of 0.
905 g / cm ³ ; melt mass flow rate 0.85 g
/ 10 minutes; Mw / Mn = 3.7; Trade name: DFDA-1
137, Union Carbide Co. (polymerized with Ziegler catalyst)

(B) Styrenic thermoplastic elastomer (B-1): Styrene-isoprene-styrene copolymerization
Body; density 0.92 g / cm³; Melt mass flow rate
23 g / 10 minutes (measured at 230 ° C.); Trade name: Krate
D-1112, made by Shell Japan (B-2): hydrogenated styrene-butadiene rubber; density 0.
89 g / cm³Melt mass flow rate 30g / 10
Min (measured at 230 ° C); trade name: 8600HSRB, day
Made by this synthetic rubber company (B-3): Saturated styrene thermoplastic elastomer;
Density 0.91g / cm ³; Melt mass flow rate 25
g / 10 minutes (measured at 230 ° C); Trade name: Tuftec H
-1031, manufactured by Asahi Kasei

(C) Ethylene-alkyl acrylate copolymer (C-1): Ethylene-ethyl acrylate copolymer;
Melt mass flow rate 6 g / 10 min; ethyl acrylate content 18% by weight; trade name: NUC-6170S
D, made by Nippon Unicar

(D) Zeolite (D-1): CS-100, manufactured by Eishin Kasei Co., Ltd. Other components (E-1): Antioxidant: tetrakis [methylene-3-]
(3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane; trade name: Irganox 1010, manufactured by Ciba Specialty Chemicals

Polymerization raw material for plastic lens (monomer 1): 100 parts by weight of diethylene glycol bisallyl carbonate and 3 parts by weight of diisopropyl peroxycarbonate as a polymerization initiator (monomer 2): 80 parts by weight Methyl methacrylate, 2
0 parts by weight of ethylene glycol dimethacrylate, 0.5 parts by weight of 2- (5-methyl-2-) as an ultraviolet absorber.
Hydroxyphenyl) benzotriazole and 0.3 parts by weight of 2,2'-azobisisobutyronitrile as a polymerization initiator (monomer 3): 48 parts by weight of 1,3-bisisocyanatomethyl Cyclohexane, 26 parts by weight of pentaerythritol tetrakismercaptoacetate, 26 parts by weight of 2,5-dimercaptomethyldithiane, 0.2 part by weight of 2- (2'-hydroxy-5'-t as an ultraviolet absorber.
-Octylphenyl) benzotriazole, 0.2 parts by weight of butoxyethyl acid phosphate as a release agent, and 0.5 parts by weight of dimethyltin dichloride as a catalyst.

Example 1 100 parts by weight of (A-1), 30 parts by weight of (B-1),
And 0.06 part by weight of (E-1) were placed in a Banbury mixer and mixed for 10 minutes to obtain a dry blend. This dry blend was put into a twin-screw extruder, melt-kneaded at 120 ° C., and then extruded to obtain a resin composition for producing a gasket. Next, this composition was cooled with water and granulated with a strand cutter, and then an annular T-shaped gasket having an inner diameter of 65 mm was produced by injection molding. At this time, granulation property and injection moldability were evaluated. The surface of this gasket was washed by blowing antistatic air (pressure 3 kgf / cm ² ) for 5 seconds. Two lens molding dies designed to have a spherical power of −4.00 deopters and a center wall thickness of 2.0 mm, and the surface of which has been cleaned in advance, and a clamp to tighten the plastic lens molding. I made a mold. Next, (Monomer 1) was degassed under sufficient stirring and vacuum, and then filtered through a polypropylene filter having a filtration accuracy of 1.0 μm. Inject the filtrate into the prepared mold and
Polymerization was performed by gradually raising the temperature from 0 ° C. to 85 ° C. over 21 hours. The releasability was evaluated when the plastic lens was taken out from the mold. One more plastic lens taken out
After heat treatment at 20 ° C. for 1 hour, the optical performance was evaluated. A general plastic lens manufacturing process flow chart including the above series of processes is shown in FIG.

Example 2 Example 1 was repeated except that 60 parts by weight of (C-1) was additionally added to the resin composition for producing a gasket.

Examples 3a and 3b Example 1 was repeated except that 60 parts by weight of (C-1) and 1 part by weight of (D-1) were additionally compounded into the gasket manufacturing resin composition (Example 3a. ). Furthermore, (monomer 1)
This experiment was repeated substituting for (monomer 2) (Example 3b).

Example 4 (B-1) was replaced with (B-2), and 60 parts by weight of (C-1) and 1 part by weight of zeolite (D-1) were further added to the resin composition for producing a gasket. Example 1 was repeated except that it was compounded. Example 5 Example 1 was repeated except that antistatic air blowing on the surface of the gasket was replaced with water washing under the following conditions. Filtering 5 μm polypropylene filter Ultrasonic wave 600 W 28 KHz Tank configuration 25 ° C. City water 2 tank drying 30 ° C. 40 RH% Dry for 6 hours except Example 6 (monomer 1) was replaced with (monomer 3) Example 1 was repeated.

Comparative Example 1 Example 1 was repeated except that (A-1) was replaced with (A-3). Comparative Example 2 (A-1) was replaced with (A-2), and 30 parts by weight of (B-
1) was replaced with 20 parts by weight of (B-3), and further 0.6
A resin composition for producing a gasket was prepared in the same manner as in Example 1 except that an additional amount of (D-1) was added. However, agglomeration was observed in the feed hopper of the twin-screw extruder, and the obtained resin was obtained. The composition was too flexible to be cut with a strand cutter and formed into pellets.

Comparative Example 3 (A-1) was replaced with (A-2), and (B-1) was replaced with (B-
Instead of 3), 60 parts by weight of (C-1) and 1 part by weight of (D
Example 1 was repeated except that -1) was additionally compounded with the resin composition for producing a gasket.

Comparative Examples 4a and 4b 30 parts by weight of (B-1) was replaced by 2 parts by weight, and 40 parts by weight was further added.
Example 1 was repeated except that 1 part by weight of (D-1) and 1 part by weight of (C-1) were additionally compounded (Comparative Example 4a). Furthermore, this experiment was repeated by replacing (Monomer 1) with (Monomer 2) (Comparative Example 4b).

Comparative Example 5 30 parts by weight of (B-1) was replaced with 60 parts by weight, and further 4 parts were obtained.
A gasket manufacturing resin composition was prepared in the same manner as in Example 1 except that 0 part by weight of (C-1) and 1 part by weight of (D-1) were additionally added to the gasket manufacturing resin composition.
Agglomeration was observed in the feed hopper of the twin-screw extruder, and the obtained resin composition was too flexible to be cut by a strand cutter and could not be formed into pellets.

The compositions of the resin compositions prepared in the above Examples and Comparative Examples are shown in Table 1, and the evaluation results of the physical properties, granulation properties and injection moldability are shown in Table 2.

[0059]

[Table 1]

[0060]

[Table 2]

As is clear from Table 2, Examples 1 to 6,
The resin compositions of Comparative Examples 1 and 4 passed the granulation property and injection moldability. On the other hand, in Comparative Examples 2 and 5, the resin composition was too flexible to be cut by the strand cutter and could not be formed into pellets. Although the resin composition of Comparative Example 3 passed the granulation property, the melt mass flow rate as a flow characteristic was smaller than that of the resin composition of Example,
The Vicat softening temperature was low, the hardness was insufficient, and the rigidity (stiffness) was about half. This resin composition was sticky and failed injection molding. On the contrary, the resin composition of Comparative Example 4, which passed the granulation property and the injection moldability, had a high hardness and a high stiffness as compared with the Examples.

Next, Table 3 shows the evaluation results of the plastic lenses molded using the gaskets obtained from the resin compositions of Examples 1 to 6 and Comparative Examples 1, 3 and 4 which passed the granulation property. .

[0063]

[Table 3]

As is clear from Table 3, the gaskets produced from the resin compositions of Examples 1 to 6 passed the retrievability of the plastic lens, and the plastic lens molded therefrom had neither clouding nor striae. However, it had good transparency and was suitable for optical applications. In particular, the odor when the plastic lens was molded with the gasket manufactured from the resin composition of Example 3 was obviously smaller than that of Example 2.

On the other hand, the gasket manufactured from the resin composition of Comparative Example 1 had a poor removability of the plastic lens, and the molded plastic lens had cloudiness and striae. Further, foreign matter was observed, and sufficient cleaning could not be performed by the antistatic air blowing cleaning. In the gasket manufactured from the resin composition of Comparative Example 3, tackiness was also added, and the removability of the plastic lens was further deteriorated, and some leakage was observed. Fogging and striae were observed on the molded plastic lens, and foreign matter was observed.
In the resin composition of Comparative Example 4, the gasket was too hard to take out the plastic lens. The plastic lens produced in Comparative Example 4a had no haze, but in Comparative Example 4b, a slight haze was observed. Striae were found in all the plastic lenses.

[0066]

Industrial Applicability According to the present invention, a resin composition for producing a plastic lens mold casting gasket having good injection moldability is provided, and a gasket produced from the resin composition has good flexibility, heat resistance and air resistance due to antistatic property.・ Has water washability and plastic lens removal properties. Since the plastic lens manufactured with this gasket does not cause clouding or striae, it can be suitably used for optical applications.

[Brief description of drawings]

FIG. 1 is a schematic view of a gasket.

FIG. 2 is a schematic view of a plastic lens molding mold formed by combining a gasket and a lens molding die.

FIG. 3 is a flowchart of a general plastic lens manufacturing process.

[Explanation of symbols]

1 gasket 2 Mold for lens molding 3 Lens mold 4 Polymerization raw materials for plastic lenses 5 clamps

─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Toshihisa Kawakami 1041-11 Ninomiya, Akiruno-shi, Tokyo (72) Inventor Yuji Hoshi 4-2520-16 Wakasa, Tokorozawa, Saitama Prefecture (56) Reference JP 2000-191846 ( (58) Fields surveyed (Int.Cl. ⁷ , DB name) C08L 1/00-101/16 C08K 3/00-13/08 G02B 3/00

Claims (5)

(57) [Claims] 1. A resin composition for producing a plastic lens mold casting gasket, comprising: (A) a density of 0.89 to 0.93 g / cm ³ and a melt mass flow rate of 3 to 30 g / 10 minutes, Ethylene having a ratio (Mw / Mn) of weight average molecular weight (Mw) to number average molecular weight (Mn) of 2.0 to 3.5.
α-olefin copolymer; (B) styrene-based thermoplastic elastomer; and (C) melt mass flow rate of 3 to 30 g / 10 minutes, and alkyl acrylate content of 10 to 25.
The ethylene-alkyl acrylate copolymer, which is the weight%, is (A) :( B) :( C) = 100: 5 to 50: 0 to 7.
A resin composition comprising a weight ratio of 0. 2. The (D) zeolite is further replaced by the (A):
(B) :( C) :( D) = 100: 5-50: 0-7
The resin composition according to claim 1, comprising a weight ratio of 0: 0.05 to 5. 3. A plastic lens molding mold gasket manufactured from the resin composition according to claim 1. 4. A method of manufacturing a plastic lens, comprising: injecting a liquid containing a polymerization raw material for a plastic lens into a plastic lens molding mold comprising the plastic lens molding mold gasket according to claim 3.
And a method comprising polymerizing the polymerization raw material under conditions sufficient for the polymerization. 5. The method further comprises air-cleaning and / or water-cleaning the plastic lens molding die gasket before injecting a liquid containing a polymerization raw material for plastic lenses into the plastic lens molding die.
The method of claim 4.