JP3339364B2 - Resin composition and plastic lens molding gasket - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to relates to a resin composition and a positive <br/> tic lens molding gasket used in gaskets for molding plastic lens. More specifically, the present invention is characterized in that it has moderate flexibility, has improved heat resistance, and does not cause fogging of the lens when producing a high-temperature polymerization type special lens by casting polymerization. it relates molding plastic lens gasket comprising the resin composition used in the plastic lens molded gasket and the resin composition having.

[0002]

2. Description of the Related Art Plastic lenses are mainly used as spectacle lenses because of their light weight and excellent impact resistance and dyeability. A plastic lens is usually manufactured by injecting a liquid monomer such as diethylene glycol bisallyl carbonate between glass molds, polymerizing and curing in a heating furnace, and then removing the mold. Here, a gasket made of resin is usually used to hold the glass mold at appropriate intervals and to prevent leakage of the liquid monomer.

[0003] The gasket follows the change in the volume of the monomer during the solidification of the liquid monomer during the casting polymerization, and requires a certain degree of flexibility to facilitate the assembly and removal of the mold. Good heat resistance is required because it is kept at a high temperature for a long time. Conventionally, as a gasket material satisfying such required performance, an ethylene-vinyl acetate copolymer, an ethylene-methyl methacrylate copolymer, or the like has been used. However, these resins, which have been conventionally used as gasket materials, have been found to be 80-9%, such as diethylene glycol bisallyl carbonate.
Although applicable to a monomer polymerized at a relatively low temperature of 0 ° C., a recently developed monomer for a high-performance plastic lens which is polymerized at a higher temperature of 100 to 130 ° C., for example, JP-A-60-51706 Cannot be used for the urethane-containing acrylic monomer and the like disclosed in Japanese Patent Application Laid-Open No. H11-157572 due to the problem that the gasket melts and loses shape during polymerization.
To address this problem, polypropylene resins, hydrogenated styrene / conjugated diene-block copolymers and mineral oil-based softeners exemplified in JP-A-50-14742, JP-A-52-65551, etc. And a composition comprising an ethylene-α-olefin copolymer rubber partially cross-linked with a polypropylene resin and a mineral oil-based softener. However, these have no problem in terms of heat resistance, but have a problem that the polymerized lens becomes cloudy.

[0004]

Under such circumstances, the problem to be solved by the present invention is to provide a special lens having a moderate flexibility, improved heat resistance, and a high temperature polymerization type by casting polymerization. resides in providing a plastic lens molded gasket comprising the resin composition used in the plastic lens molded gasket and the resin composition having the characteristic of not causing fogging on the lens during the manufacturing.

[0005]

That is, the first aspect of the present invention relates to a gasket for molding a plastic lens.
It is a resin composition used, and the following (A) component 10
The present invention relates to a resin composition containing 50% by weight, 3 to 30% by weight of the component (B), and 85 to 20% by weight of the component (C). (A): a polyolefin having a melting point of 130 ° C. or more (B): a block composed of at least one polymer block mainly composed of a vinyl aromatic compound and at least one polymer block mainly composed of a conjugated diene compound Hydrogenated block copolymer obtained by hydrogenating a polymer and having a number average molecular weight of 100,000 or more and less than 1,000,000 (C): at least one vinyl aromatic compound-based polymer block and at least A hydrogenated block copolymer obtained by hydrogenating a block copolymer comprising a polymer block mainly composed of one kind of conjugated diene compound and having a number average molecular weight of 10,000 or more and less than 100,000

A second aspect of the present invention relates to a plastic lens molding gasket comprising the above resin composition.

[0007]

[0008]

DETAILED DESCRIPTION OF THE INVENTION The component (A) of the present invention has a melting point of 13%.
It is a polyolefin of 0 ° C. or higher. Specific examples of the polyolefin include a polypropylene resin and a copolymer resin of propylene and another α-olefin.

The component (A) has a melting point of 130 ° C. or higher,
Preferably it is 135-250 degreeC. If the melting point is too low, the gasket will lose its shape during the production of the lens, while if the melting point is too high, the production of the gasket may be difficult.

The component (B) of the present invention comprises a block copolymer comprising at least one polymer block mainly composed of a vinyl aromatic compound and at least one polymer block mainly composed of a conjugated diene compound. A hydrogenated block copolymer obtained by hydrogenation and having a number average molecular weight of 100,000 or more and less than 1,000,000.

[0011] As the vinyl aromatic compound, styrene,
α-methylstyrene, o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, 1,3-dimethylstyrene, vinylnaphthalene, vinylanthracene, and the like.

As the conjugated diene compound, butadiene,
Examples include isoprene, 1,3-pentadiene, and 1,3-hexadiene.

The degree of hydrogenation is usually at least 70%.

The component (B) has a number average molecular weight of 100,000 or more,
It is less than 1,000,000, preferably 130,000 to 300,000. If the number average molecular weight is too small, the elastic properties are inferior,
On the other hand, when the number average molecular weight is too large, the moldability becomes poor. The number average molecular weight is determined by a GPC method.

As the component (B) of the present invention, corresponding commercially available products can be used. For example, “Clayton G” of Shell Chemical Co., “Septon” of Kuraray Co., Ltd., and “Toughtec” of Asahi Kasei Co. Name) can be used.

The component (C) of the present invention comprises a block copolymer comprising at least one polymer block mainly composed of a vinyl aromatic compound and at least one polymer block mainly composed of a conjugated diene compound. It is a hydrogenated block copolymer obtained by hydrogenation and having a number average molecular weight of 10,000 or more and less than 100,000.

Examples of the vinyl aromatic compound and the conjugated diene compound include the same compounds as those described in the section of the component (B). In addition, the degree of hydrogenation can be exemplified by the same degree as that of the component (B). However, the compound and the degree of hydrogenation do not need to be the same between the component (A) and the component (B).

Component (C) has a number average molecular weight of 10,000 or more,
It is less than 0,000, preferably 30,000-70,000. If the number average molecular weight is too small, the adhesiveness of the gasket surface increases, while if the number average molecular weight is too large, the fluidity becomes insufficient,
Molding processability becomes poor.

As the component (C) of the present invention, a corresponding commercially available product can be used.

The resin composition of the present invention comprises the component (A)
It contains 50% by weight, 3 to 30% by weight of component (B) and 85 to 25% by weight of component (C), preferably 15 to 30% by weight of component (A) and 5 to 20% by weight of component (B). % (C) and 40 to 70% by weight of the component (C). When the amount of the component (A) is too small, the heat resistance becomes poor. On the other hand, when the amount of the component (A) is too large, the composition lacks flexibility and cannot be easily assembled or removed, resulting in poor workability. (B)
If the amount of the component is too small, the elasticity becomes insufficient and the material tends to be deformed. On the other hand, if the amount of the component (B) is too large, the fluidity decreases and the moldability deteriorates. When the amount of the component (C) is too small, the molding processability is poor and the flexibility is insufficient. On the other hand, when the amount of the component (C) is too large, the adhesiveness increases and the workability becomes poor.

The resin composition of the present invention may contain, in addition to the essential components (A) to (C), optional components to such an extent that the effects of the present invention are not impaired. For example, for the purpose of facilitating desorption from a mold, a higher fatty acid amide and / or an antistatic agent is added in a total amount of 0.03 to 2 parts by weight based on 100 parts by weight of the components (A) to (C). May be used. Further, an olefin copolymer rubber such as an ethylene-α-olefin rubber may be used as long as the performance is not impaired.

The resin composition of the present invention can exhibit a flexibility of Shore A hardness of less than 90 without using a mineral oil-based softening agent, thereby preventing the disadvantages associated with the mineral oil-based softening agent. This feature has the advantage that it has moderate flexibility, has excellent heat resistance, and does not cause fogging of the lens when producing a special lens of high temperature polymerization type by casting polymerization, and is used for plastic lens molding. It can be optimally used for gaskets.

[0023]

The present invention will be described below with reference to examples. The raw materials used and the evaluation method are as shown below. In addition, the test method used for the physical property measurement in these Examples is as follows. (1) Hardness: based on ASTM D-2240. (A
(Type, instantaneous value) (2) 100% modulus: Stress per cross-sectional area at 100% elongation was measured according to JIS K-6301. (JIS-3 dumbbell, pulling speed 200mm / m
in) (3) Stress at break: Based on JIS K-6301.
(JIS-3 dumbbell, pulling speed 200mm / mi
n) (4) Elongation at break: Same as above (5) Compression set: Based on JIS K-6301. (23 ° C. or 70 ° C., 22 hours, compression ratio 25%) (6) MFR: Based on JIS K-7210.
(230 ° C., load 2.16 kg) (7) Number average molecular weight: gel permeation chromatography (GPC) method: tetrahydrofuran (T
HF), polystyrene was used as a standard substance, and the number average molecular weight was calculated as a polystyrene equivalent value.

Example 1 A propylene-ethylene copolymer [P] having an MFR of 20, a melting point of 145 and an ethylene content of 3.2% by weight was used as the component (A).
P] is 20% by weight, and as the component (B), Clayton G1651 (number average molecular weight = 160,000, styrene-butadiene styrene block copolymer (SBS) manufactured by Shell Chemical Co., Ltd.)
15% by weight of a hydrogenated styrene-ethylenebutylene-styrene block copolymer [SEBS]),
(C) Septon 2063 manufactured by Kuraray Co., Ltd. as a component
(Number average molecular weight = 45,000, styrene which is a hydrogenated product of styrene-isoprene-styrene block copolymer and styrene-isoprene block copolymer (SIS)
Ethylene propylene-styrene block copolymer and styrene-ethylene propylene block copolymer [SEP
S]), and 0.1 parts by weight of erucamide (lubricant) and 0.2 parts by weight of monoglyceride stearate (antistatic agent) per 100 parts by weight of these in a Banbury mixer at 160-200 ° C, 8 parts by weight. After melt-kneading for minutes, it was pelletized using an extruder. Injection molding was performed using this composition, and physical properties were evaluated using the injection molded product. Table 1 shows the results. By using the composition, it is possible to obtain a gasket for forming a molded product that is flexible and has high moldability, particularly a lens having a high refractive index without fogging, without using a mineral oil-based softening material.

Example 2 [SEBS] was added in an amount of 10% by weight and [SEP] in Example 1.
S] was set to 70% by weight, and the same procedure as in Example 1 was carried out except that (antistatic agent) was not added. Table 1 shows the results. By using the composition, it is possible to obtain a gasket for forming a molded product that is flexible and has high moldability, particularly a lens having a high refractive index without fogging, without using a mineral oil-based softening material.

Example 3 In Example 1, 27% by weight of [PP] and [SEBS]
Is 5% by weight, [SEPS] is 20% by weight, and as other components, an ethylene-butene copolymer [EBR] having an MFR of 13 and a butene content of 22 is used in an amount of 48% by weight. 0.2 parts by weight, except that no (antistatic agent) was added. Table 1 shows the results. By using the composition, it is possible to obtain a gasket for forming a molded product that is flexible and has high moldability, particularly a lens having a high refractive index without fogging, without using a mineral oil-based softening material.

[0027]

[Table 1] * 1 Amount of additives: parts by weight per 100 parts by weight of polymer component

[0028]

As described above, according to the present invention, the softness is improved, the heat resistance is improved, and fogging occurs in the production of a special lens of high temperature polymerization type by casting polymerization. it resin composition used in the plastic lens molded gasket has a feature that no 及
And a plastic lens molding gasket comprising the resin composition.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ identification code FI // B29L 11:00 B29L 11:00 (58) Investigated field (Int.Cl. ⁷ , DB name) C08L 23/00-23 / 36 C08L 53/00-53/02 B29C 33/00-33/76 B29C 39/00-39/44 G02B 1/04

Claims (7)

(57) [Claims] 1. A resin composition used for a plastic lens molding gasket, comprising the following component (A) 10:
A resin composition containing 50% by weight, 3 to 30% by weight of the component (B), and 85 to 20% by weight of the component (C). (A): a polyolefin having a melting point of 130 ° C. or more (B): a block composed of at least one polymer block mainly composed of a vinyl aromatic compound and at least one polymer block mainly composed of a conjugated diene compound Hydrogenated block copolymer obtained by hydrogenating a polymer and having a number average molecular weight of 100,000 or more and less than 1,000,000 (C): at least one vinyl aromatic compound-based polymer block and at least A hydrogenated block copolymer obtained by hydrogenating a block copolymer comprising a polymer block mainly composed of one kind of conjugated diene compound and having a number average molecular weight of 10,000 or more and less than 100,000 2. The resin composition according to claim 1, wherein the component (A) is a polypropylene resin or a copolymer resin of propylene and another α-olefin. 3. The resin composition according to claim 1, wherein the vinyl aromatic compound of component (B) and component (C) is styrene. 4. The resin composition according to claim 1, wherein the conjugated diene compound of the component (B) and the component (C) is butadiene or isoprene. 5. The resin composition according to claim 1, which has a Shore A hardness of less than 90 and does not contain a mineral oil-based softener. 6. A higher fatty acid amide and / or an antistatic agent in an amount of 0.1 part by weight per 100 parts by weight of the resin composition according to claim 1.
The resin composition according to claim 1, which is added in an amount of from 03 to 2 parts by weight. 7. A plastic lens molding gasket comprising the resin composition according to any one of claims 1 to 6.