JPH0333083B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to a mold for producing a hydrophilic plastic lens, and more specifically, a mold for producing a hydrophilic plastic lens by cast polymerization of a mixture containing a monomer having a hydrophilic group. Regarding the mold used when

[Conventional technology]

When producing plastic lenses by cast polymerization, a combination mold consisting of a glass mold made of silicate or borate glass and a resin gasket is usually used. Although such a template is suitable for cast polymerization of hydrophobic plastic lenses such as polydiethylene glycol bisallyl carbonate and polymethyl methacrylate, it cannot be used for cast polymerization of plastic lenses having hydrophilic groups. The reason for this is that plastic lenses having hydrophilic groups have excellent adhesion to ordinary glass, making it extremely difficult to remove the plastic lenses from the glass mold at the end of polymerization. Therefore, when performing cast polymerization of plastic lenses containing such hydrophilic groups, an example has been proposed in which a mold made of a specific material is used.

Namely, Japanese Patent Publication No. 55-2605 and Japanese Patent Application Laid-open No. 57-
Publication No. 189114 discloses a mold made of polyethylene, polypropylene, etc.
Publication No. 46734 describes the use of polyallyl diglycol carbonate as a template.

[Problem that the invention seeks to solve]

However, when a plastic lens with hydrophilic groups is cast-polymerized using a mold made of polyethylene, polypropylene, etc., these molds have excellent mold releasability from the hydrophilic plastic lens, but do not impart an optical surface to the lens. It has the disadvantage of not being possible. Therefore, at present, hydrophilic plastic lenses manufactured using these molds are polished on both sides to obtain optical surfaces.

On the other hand, in the case of a mold made of polyallyl diglycol carbonate, the optical surface of the hydrophilic plastic lens produced and the releasability between the hydrophilic plastic lens and the mold are excellent, but the durability of the mold
Due to the lack of rigidity, molds must be replaced frequently on actual production lines.

[Means for solving problems]

The present invention provides good mold releasability from the hydrophilic plastic lens when producing the plastic lens having a hydrophilic group by cast polymerization, can provide the plastic lens with an excellent optical surface, and is durable. The aim is to provide molds with excellent properties, surface precision, and rigidity.

The present invention focuses on the fact that the mold itself made of fluorine-based glass has excellent durability, surface precision, and rigidity, and the molecules of fluorine-based glass form a primary bond with the raw material monomer of hydrophilic plastic through a chemical reaction. In addition, the adhesive force between the two due to the attraction due to intermolecular forces is small, and the adhesive force based on the electrostatic attraction between the fluorine glass mold and the raw material monomer of the hydrophilic plastic is small, and the wettability of the two is low. As a result of focusing on characteristics such as small Features.

In the present invention, as raw material monomers for plastic lenses having hydrophilic groups,
Hydroxy lower alkyl acrylate, hydroxy lower alkyl methacrylate, hydroxy lower alkoxy lower alkyl acrylate, hydroxy lower alkoxy lower alkyl methacrylate, polyethylene glycol monoacrylate, polyethylene, etc., described in Publications No. 47427, No. 55-6062, No. 57-46734, etc. Glycol monomethacrylate, polyethylene glycol diacrylate,
Typical examples include polyethylene glycol dimethacrylate, phosphoric acid acrylate, phosphoric acid methacrylate, acrylic acid, methacrylic acid, acrylamide, methacrylamide, etc., but are not limited thereto. Typical examples of the hydroxy lower alkyl acrylate include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and 2,3-dihydroxypropyl acrylate, and examples of the hydroxy lower alkyl methacrylate include 2-hydroxyethyl methacrylate. ,2
-Hydroxypropyl methacrylate, 2,3-
Representative examples include dihydroxypropyl methacrylate.

In the present invention, cast polymerization includes not only the commonly used method using a polymerization initiator, but also polymerization using ultraviolet rays or radiation irradiation.

The mold used in such cast polymerization is made of fluorine glass. Examples of the fluorine-based glass include fluoride phosphate glass, fluoride silicate glass, and fluoride borosilicate glass. The content of fluorine in these fluorine-based glasses is preferably 1% by weight or more. If the fluorine content in the glass is less than 1% by weight, primary bonding occurs due to chemical reaction between the raw material monomer of the hydrophilic plastic lens and the molecules in the fluorine-based glass, and attraction between the two occurs due to intermolecular attraction. The wettability tends to decrease. Fluorides added to glass include BeF ₂ , CaF ₂ , MgF ₂ , SrF ₂ ,
Examples include BaF ₂ , AlF ₃ , CeF ₂ , LaF ₃ , PbF ₂ , ThF ₂ and the like.

Preferred composition examples of the fluorine-based glass used as the mold of the present invention are shown below.

(a) Composition example of fluoride phosphate glass 1/2 P ₂ O ₅ 5-25% by weight AlF ₃ 20-35 〃 YF ₃ 0-5 〃 BaF ₂ +SrF ₂ +CaF ₂ +MgF ₂ 22-55 〃 NaF+KF+LiF 0- 25 〃 1/2Nd ₂ O ₃ 0.01-3 〃 1/2B ₂ O ₃ 0-25 〃 (B) Composition of fluoride silicate glass SiO ₂ 30-50% by weight K ₂ TiF ₆ 5-52 〃 TiO ₂ 0 to 32 〃 K ₂ O 0 to 32 〃 As ₂ O ₃ 0.1 to 3 〃 FC-1, FC-3, manufactured by Hoya Glass Co., Ltd. are commercially available products of fluorine-based glass used as the mold of the present invention.
FC-5, FCD-1, FCD-3, FCD-5, FCD
-10 etc.

Cast polymerization molds are subjected to extremely large forces during shrinkage and mold release during polymerization, so the molds must have durability, surface precision, and rigidity, and the glass mold surface must have minimal scratches. Even if this happens, the resulting lenses will have serious defects, and these scratches will grow further due to the pressure and pushing force applied during mold release, and the resulting lenses will require polishing, cleaning, and drying. . Fluorine-based glasses can satisfy these requirements, but in particular 1/2P ₂ O ₅ is required to increase stability against devitrification, improve processability, and improve mechanical properties such as rigidity. −1/2B ₂ O ₃
-Me(F) (here, Me(F) refers to the above-mentioned fluoride) optical glass is preferably used.

The above-mentioned fluorine-based glass material is sanded and polished, and the surface is processed into a shape having a desired constant curvature to obtain the mold of the present invention. Note that this mold is preferably air-cooled and strengthened.

〔Effect of the invention〕

The mold of the present invention has good mold releasability from hydrophilic plastics, is rich in durability, surface precision, and rigidity, and is also excellent in workability. According to the method for manufacturing a plastic lens, a hydrophilic plastic lens having an excellent optical surface can be stably and easily manufactured by reducing the frequency of mold replacement.

〔Example〕

Example 1 2,3-dihydroxypropyl methacrylate
60 parts, 30 parts of tetraethylene glycol dimethacrylate, 10 parts of ethylene glycol dimethacrylate
A mold made of fluorine-based glass FCD-1 (manufactured by Hoya Glass) made of a monomer mixture consisting of 0.3 parts and 0.3 parts of azobisisobutyronitrile polished to a mirror finish, and a polyvinyl chloride gasket. Pour into the frame and heat the mold from 45℃ to 80℃ for 24 hours.
After increasing the temperature over a period of time, the mold and the lens were separated. The FCD-1 mold and the lens were separated by blowing air between them using an air gun to apply cooling and pressure to the contact surface between the two. As a result, the FCD-1 mold was easily peeled off from the lens. Next, when we performed an external and internal inspection of the surface of the lens using a condensing irradiator, we found that mold material remained on the lens due to partial contact between the mold and the lens. The molded product had no surface defects such as burrs or bubbles, and had an excellent optical surface, and there were no abnormalities inside the lens, confirming that it is suitable as a mold for producing hydrophilic plastics. Furthermore, the mold was stable even when molding a large number of lenses continuously.

Example 2 A monomer mixture consisting of 90 parts of 2-hydroxyethyl methacrylate, 5 parts of methacrylic acid, 5 parts of tetraethylene glycol dimethacrylate, and 0.5 parts of di-3-methoxybutyl peroxydicarbonate was polished to a mirror surface. It was poured into a mold made of a finished fluorine glass FCD-5 (manufactured by Hoya Glass) and a polyethylene gasket, and kept at 40°C for 20 hours, 60°C for 2 hours, and 80°C for 2 hours. , the mold and the lens were separated.
The separation between the FCD-1 mold and the lens and the surface and interior of the obtained lens were as good as in Example 1.

Comparative example 1 2,3-dihydroxypropyl methacrylate
60 parts, 30 parts of tetraethylene glycol dimethacrylate, 10 parts of ethylene glycol dimethacrylate
The mold consisted of a mold made of borosilicate glass BSC-7 (manufactured by Hoya Glass Co., Ltd.) and a gasket made of polyvinyl chloride, which was made by polishing a monomer mixture consisting of 0.3 parts of azobisisobutyronitrile and 0.3 parts of azobisisobutyronitrile. Pour into the mold and heat the mold from 45℃ to 80℃
The temperature was increased over 24 hours. Thereafter, the gasket was removed and an attempt was made to separate the BSC-7 mold and lens in the same manner as in Example 1, but this was not possible. I also tried to drive a V-shaped wedge into the contact surface between the BSC-7 mold and the lens and try to separate them again, but the two did not separate, and I applied pressure to the wedge and drove it in.
The BSC-7 mold was damaged and at the same time scratches appeared on the lens surface.

Claims (1)

[Scope of Claims] 1. A mold for producing a hydrophilic plastic lens, characterized in that the mold is made of fluorine-based glass, in a mold for cast polymerization of a mixture containing a monomer having a hydrophilic group. 2. The mold for producing a hydrophilic plastic lens according to claim 1, wherein the fluorine-based glass is a glass having a fluorine content of 1% by weight or more. 3. The mold for producing a hydrophilic plastic lens according to claim 1, wherein the fluorine-based glass is tempered glass.