JPH0580718U - Gasket for plastic lens polymerization - Google Patents

Abstract

(57) [Summary] (Revised) [Purpose] To obtain an annular gasket that is less likely to leak plastic monomer and has excellent followability to shrinkage due to polymerization. [Structure] A pair of molds (11, 12); an annular gasket 13 each having a pair of receiving surfaces (14, 15) with which the peripheral parts of the pair of molds come into contact, and which determines the distance between the pair of molds. In a plastic lens polymerization mold 10 including and, at least one receiving surface of the annular gasket 13 (14 or 15) is in contact with the molds (11, 12) in a closed linear shape, and has a chevron cross section. A plastic lens molding gasket 13 provided with at least one linear contact portion (14a, 15a).

Description

[Detailed description of the device]

[0001]

【Technical field】

 The present invention relates to a mold used for polymerizing a plastic lens, and particularly to a gasket thereof.

[0002]

[Prior art and its problems]

 A mold in which a pair of molds made of glass or ceramics are held at a predetermined interval by an annular gasket is used for polymerization molding of plastic lenses. By filling a plastic monomer in this mold and polymerizing by heating, a plastic lens having a required shape can be obtained.

At the time of this polymerization, in order to prevent the leakage of the plastic monomer, a pair of molds is pressed against the mold receiving surface of the annular gasket with a clip having a spring property. However, in the conventional mold, it is difficult to completely prevent the leakage of the plastic monomer, and the occurrence of defects due to the monomer leakage cannot be avoided.

Further, during the polymerization, the plastic monomer shrinks by about 10 vol%. Therefore, it is desirable for the gasket to follow this contraction as much as possible, but this contraction naturally occurs in both the radial direction and the thickness direction of the lens, so simply pressing a pair of molds against the annular gasket will In particular, the gasket cannot follow the radial contraction, which causes defective molding.

[0005]

[The purpose of the device]

 The present invention aims to obtain an annular gasket that is less likely to cause liquid leakage of plastic monomers and has better followability to shrinkage due to polymerization, based on the above-mentioned awareness of problems regarding conventional molding molds. To do.

[0006]

SUMMARY OF THE INVENTION According to the present invention, at least one linear contact portion having a chevron-shaped cross section, which is in contact with a casting mold in a closed linear shape, is provided on at least one receiving surface of an annular gasket with which the mold contacts. The feature is that it is provided. When a linear contact part is provided on the receiving surface and makes linear contact with the mold in this way, the surface pressure of the linear contact part will be higher than that of a conventional product that receives a wide surface, and leakage will occur. Hateful. Also, even when the polymerization shrinkage occurs in the radial direction, the chevron contact portion has a high degree of freedom of deformation in the same direction, so that molding defects are less likely to occur.

[0007] For example, one chevron-shaped linear contact portion is provided at the inner peripheral end of the receiving surface, and the receiving surface outside the linear contact portion is not in contact with the mold and is a space between the mold and the receiving surface. Can be formed. Alternatively, a plurality of the chevron-shaped linear contact portions may be continuously provided to have a sawtooth cross section as a whole. The pair of receiving surfaces are formed on the upper and lower end surfaces of the tubular portion located between the pair of molds, and at least one of the casting molds can be provided with a fitting portion with the tubular portion.

[0008]

[Example of device]

 The present invention will be described below with reference to illustrated embodiments. FIG. 1 is a sectional view of a mold 10 having an annular gasket according to the present invention. The mold 10 is composed of a pair of flat glass molds 11 and 12 and an annular gasket 13 that holds the glass molds 11 and 12 at predetermined intervals.

The gasket 13 has a large-diameter cylindrical portion 13a into which the glass mold 11 in the upper part of the figure is fitted, and a small-diameter cylindrical portion 13b having a smaller diameter than the large-diameter cylindrical portion 13a, which is a disconnection member. It is structured like a plane staircase. The upper end surface of the small-diameter cylindrical portion 13b in the figure constitutes the receiving surface 14 of the glass mold 11, and the lower end surface thereof constitutes the receiving surface 15 of the glass mold 12 in the lower part of the figure. The feature of the present invention resides in that the receiving surfaces 14 and 15 are not flat surfaces, and chevron-shaped linear contact portions 14a and 15a are provided at the inner peripheral side end portions thereof.

A contact surface 11 a with the receiving surface 14 (the linear contact portion 14 a) is formed on the lower edge of the glass mold 11 in the figure, and the receiving surface 15 a is formed on the upper edge of the glass mold 12 in the figure. A contact surface 12a with the (linear contact portion 15a) is formed. The contact surfaces 11a and 12a are both formed in a flat surface, and therefore the contact surface 11a and the linear contact portion 14a, and the contact surface 12a and the linear contact portion 15a make a line contact in a closed circular shape. A space 16 is formed outside the line contact portion. The glass mold 12 includes a fitting portion 12b that fits into the small-diameter cylindrical portion 13b, and the fitting causes the glass mold 12 to be positioned in the radial direction. The positioning of the glass mold 11 in the radial direction is performed by the large-diameter cylindrical portion 13a.

In the main mold 10 having the above-described structure, the mold space 17 formed by the glass molds 11 and 12 and the gasket 13 is filled with a pre-measured plastic monomer, and then the glass molds 11 and 12 are clipped by a clip (not shown). A mold closing force P is applied to. Then, the linear contact portion 14a in contact with the glass mold 11 and the linear contact portion 15a in contact with the glass mold 12 are elastically deformed and the contact surface 11a and the contact surface are subjected to high surface pressure. Contact 12a to prevent monomer leakage. Of course, the elastic deformation allowance (shrinkage allowance) is calculated in advance.

Then, as the heat polymerization progresses, the plastic lens to be polymerized and molded contracts, and the linear contact portions 14a and 15a elastically deform and follow this contraction as well. This elastic deformation can be expected to some extent not only in the thickness direction of the molded lens but also in the radial direction. This effect is apparent when compared to a conventional mold in which the receiving surfaces 14 and 15 are flat and which are in full contact with the contact surfaces 11a and 12a.

FIG. 2 shows another embodiment of the gasket 13A of the present invention. In this embodiment, a plurality of chevron-shaped linear contact portions 18 are continuously formed on the receiving surface 14A of the gasket 13A that contacts the contact surface 11a of the glass mold 11, and a contact portion 19 having a serrated cross section is formed as a whole. It is a constructed example. The receiving surface 15A of the gasket 13A which comes into contact with the contact surface 12a of the glass mold 12 forms a trapezoidal contact portion 20 having a narrow flat surface portion.

According to this embodiment, the linear contact portion 18 (serrated contact portion 19) can achieve the same effect as that of the first embodiment, and further, the plurality of concentric closed circular shapes can be obtained. The contact portion can prevent the monomer from leaking more reliably.

In the above embodiment, the glass mold 12 is provided with the contact surface 12a that fits into the small-diameter cylindrical portion 13b. However, as shown by the chain line in FIGS. The present invention can be realized even if the large-diameter cylindrical portion 13c fitted to the outer diameter of is provided.

[0016]

[Effect of the device]

 As described above, according to the plastic lens polymerization annular gasket of the present invention, the linear contact portion having the chevron cross section provided on the receiving surface of the gasket increases the contact pressure with the mold to prevent the liquid leakage of the monomer. be able to. Further, the linear contact portion having the chevron cross section is considered to be well deformed following the polymerization shrinkage of the lens to be polymerized and molded due to its elasticity, so that reduction of molding defects can be expected.

[Brief description of drawings]

1 is a cross-sectional view of a plastic lens polymerization mold having an annular gasket according to the present invention.

FIG. 2 is a cross-sectional view of a plastic lens polymerization mold having an annular gasket of another shape according to the present invention.

[Explanation of symbols]

 10 Mold 11 12 Glass Mold 13 13A Gasket 13a Large Diameter Cylindrical Part 13b Small Diameter Cylindrical Part 14 14A 15 15A Receiving Surface 14a 15a 18 Linear Contact Part 19 Serrated Contact Part

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Morio Takamizawa 2-36-9 Maeno-cho, Itabashi-ku, Tokyo Inside Asahi Kogaku Kogyo Co., Ltd.

Claims (4)

[Scope of utility model registration request] 1. A plastic lens for polymerizing, comprising: a pair of molds; and an annular gasket which has a pair of receiving surfaces with which the peripheral portions of the pair of molds come into contact, and determines an interval between the pair of molds. In the mold, at least one of the pair of receiving surfaces of the annular gasket is provided with at least one linear contact portion having a chevron cross section, which is in contact with the mold in a closed linear shape. Lens polymerization gasket. 2. The gasket according to claim 1, wherein a plurality of chevron-shaped linear contact portions are provided and the cross-section has a serrated shape as a whole. 3. The mold according to claim 1, wherein one chevron-shaped linear contact portion is provided at an inner peripheral end portion of the receiving surface, and the receiving surface outside the linear contact portion is in non-contact with the mold. A gasket that forms a space between and. 4. The pair of receiving surfaces according to claim 1, wherein the pair of receiving surfaces are formed on upper and lower end surfaces of a tubular portion located between the pair of molds, and at least one of the molds is A gasket that has a fitting part with the tubular part.