JP2009069553A - Manufacturing method of plastic lens - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a plastic lens by which a lens layer is not deformed even when the predetermined lens layer is made thin in advance to constitute an intermediate layer in the lens with three layer structure where the intermediate layer is constituted by curing a photosensitive epoxy monomer. <P>SOLUTION: A front side lens piece 3 is formed by a first mold and a second mold, then only the first mold 1 is removed and a gel sheet 7 is stuck to the exposed front side lens piece 3. The first mold 1 is put on the gel sheet 7 and then the second mold is removed. A rear side lens piece 8 is arranged to face the re-exposed front side lens piece 3 via a spacer 9. Further the monomer is charged in a cavity C2 to be formed, is cured and then the first mold and the gel sheet 7 are removed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a plastic lens having a three-layer structure in which an intermediate layer made of a photosensitive resin is arranged between two front and rear lens precursors.

  In a lens optical system, one of the major issues is how much to reduce the aberration that occurs when light passes through the lens. For this reason, various techniques have been developed to reduce lens aberration. As one of such lens aberration reduction techniques, a technique disclosed in Patent Document 1 is cited. Patent Document 1 discloses a structure composed of two transparent plates and a refractive layer disposed between them, and is a technique that can improve aberrations when applied to a lens. For example, in the embodiment shown in FIG. 8 of Patent Document 1, an epoxy resin layer 234 is disposed as a refractive layer between the transparent covers 232 and 236. As shown in FIGS. 6 and 7, the epoxy resin layer 234 is treated (cured) so as to be in a predetermined refractive index distribution state by a light beam having high energy such as ultraviolet rays, so that the aberration is improved as a whole. It is described that an optical element is formed.

By applying the technique of Patent Document 1, a plastic lens for spectacles with actually improved aberration is manufactured. The plastic lens 1 for spectacles to which the technology is applied is generally manufactured as follows.
As shown in FIG. 15A, a spacer 103 is interposed between the first lens precursor 101 made of plastic also serving as the lower mold and the second lens precursor 102 made of plastic that also serves as the upper mold. Arrange. The first lens precursor 101 constitutes the front surface (front surface) side of the completed lens, and the second lens precursor 102 constitutes the back surface (rear surface) side. A lens having a three-layer structure in which a photosensitive epoxy monomer is filled in a cavity formed by the lens precursors 101 and 102 and the spacer 103 and solidified to form an intermediate layer 104 as shown in FIG. 105 is obtained. Thereafter, as shown in FIG. 15 (c), the lens 105 is subjected to cutting or grinding so as to have a predetermined outer shape, and the intermediate layer 104 is irradiated with ultraviolet rays so that the intermediate layer 104 has a predetermined refraction. Processing (curing) is performed so as to obtain a rate distribution state. Plastic lenses for spectacles are processed so as to have a generally circular outer shape (so-called round lens) for convenience of handling, and thinness is required for practical use. When the frequency is set on the back side as the base curve, the first lens precursor 101 side is processed as thinly as possible as shown in FIG.
US Pat. No. 6,813,082

By the way, when performing the processing as shown in FIG. 15C, it is preferable that the number of processing steps is as small as possible. Although it is difficult to omit processing around the lens to form a round lens, in FIG. 15C, if the second lens precursor 102 is not processed, it is discarded as an unnecessary part due to time loss required for processing and processing. This will eliminate the material loss of the resin. That is, if the first lens precursor 101 is made thin from the beginning, those losses should be eliminated.
However, when the first lens precursor 101 is actually thin (for example, about 0.5 mm), the following problems occur.
1) When the photosensitive epoxy monomer is filled into the cavity through the spacer 103 in the same manner as described above, the first lens precursor 101 expands due to the pressure of filling the monomer, so that it deforms.
2) Further, when heat treatment or the like is performed to cure the photosensitive epoxy monomer after filling, the first lens precursor 101 is deformed even at the stage of the heat treatment.
3) In the first place, it is very difficult to dispose the first lens precursor 101 having a small thickness on the spacer 103 without distortion.
From these, the lens layer (lens precursor) on the side opposite to the power setting side is thin in advance in the lens having a three-layer structure in which the intermediate layer is configured by curing the photosensitive epoxy monomer. Therefore, a technique for eliminating the processing step for that purpose has been demanded.
The present invention has been made paying attention to such problems existing in the prior art. The purpose is to form an intermediate layer by thinning a predetermined lens layer (lens precursor) in advance in a lens having a three-layer structure in which an intermediate layer is formed by curing a photosensitive epoxy monomer. It is an object of the present invention to provide a plastic lens manufacturing method that does not cause deformation of the lens layer.

In order to achieve the above object, in the first means, a first lens mold having a molding surface for molding one of the front surface and the back surface of the lens and molding for molding one of the other. A second lens mold having a processed surface, wherein a lens monomer adjusted in a first cavity configured by combining both lens molds in a state in which the respective processed surfaces are arranged to face each other, Filling, curing the monomer to mold the first lens precursor, and then removing either the first or second lens mold faced to the cured first lens precursor; The same lens car as the first or second lens mold, which is attached to the exposed surface of the first lens precursor with a detachable adhesive and flexible sheet and is removed on the sheet. The third lens mold having the configuration was attached, and then the first or second lens mold on the side facing the first lens precursor was removed and molded in advance. A second cavity is formed between the first and second lens precursors by disposing the first lens precursor facing the second lens precursor with a ring-shaped spacer interposed therebetween. The second photosensitive cavity is filled with the adjusted photosensitive monomer, and then the photosensitive monomer is cured to form a three-layer lens, and then the sheet body and the third lens mold are removed. This is the gist.
In addition, in addition to the configuration of the first means, the second means uses a mold equivalent to the first or second lens mold removed in advance as the third lens mold. To do.
In the third means, a first lens mold having a molding surface for molding one of the front surface and the back surface of the lens and a molding surface for molding either one of the lenses. The first lens mold is configured by winding the outer circumferences of both molds with an adhesive tape in a state where the molding surfaces of the two lens molds face each other and are spaced apart from each other. The prepared lens monomer is filled in the cavity, the monomer is cured to form the first lens precursor, and then the cured first lens precursor and the first or second lens mold The adhesive tape is cut along the boundary line with either one to remove either one of the first or second lens mold, and the exposed first lens precursor is molded in advance. A second cavity is formed between the first and second lens precursors by disposing the first lens precursor facing the second lens precursor with a ring-shaped spacer interposed therebetween. Then, after the adjusted photosensitive monomer is filled in the second cavity, the photosensitive monomer is cured to form a lens having a three-layer structure, and then the other one of the first or second that has not been removed. The gist is that the lens mold is removed.
In addition, in the invention of the fourth means, in addition to any one of the first to third means, the gist is that the spacer is made of an adhesive and flexible sheet.

In the configuration of the first means, first, a lens monomer is filled into a first cavity of a mold constituted by the first and second lens molds, and this is cured to obtain a first lens precursor. . Next, only one of the first and second lens molds is removed (demolded) from the first lens precursor. That is, the first lens precursor is continuously held by either one of the first and second lens molds. As a means for curing the lens monomer, thermal curing (including dielectric heating by microwaves), photocuring or the like is assumed.
Next, the same lens as the first or second lens mold is attached by attaching a detachable adhesive and flexible sheet to the exposed first lens precursor surface. A third lens mold having a curved configuration is attached. As a result, the first lens precursor is held again from the front and back. As the third lens mold, the removed first or second lens mold may be used as it is. It is also possible to use another first or second lens mold having the same lens curve configuration, but different from the removed first or second lens mold. The same lens curve configuration means that the curvature is the same or approximate.
Here, the sticky and flexible sheet body includes, for example, a sheet body having a thickness of several μm to several mm made of polymer gel, and the material is urethane, silicone, acrylic, etc. Is mentioned.

Next, the first or second lens mold on the side facing the first lens precursor is removed (demolded). That is, not the “one of the lens molds” that has been removed first, but the “one of the other lens molds” on the opposite side is removed. Then, the first lens precursor is arranged so as to face the second lens precursor that has been molded in advance by interposing a ring-shaped spacer. This constitutes a second cavity surrounded by the first and second lens precursors and the spacer. Next, the adjusted photosensitive monomer is filled in the second cavity, and the photosensitive monomer is cured to form a lens having a three-layer structure having an intermediate layer between the first and second lens precursors. The lens can be obtained by removing the sheet body and the third lens mold from the lens having such a configuration.
Here, the spacer may not form a complete ring. Moreover, you may be comprised with several parts. The point is that the photosensitive monomer filled in the second cavity need not be spilled, so even if a cut is partially formed, it can be dealt with by closing the lid or turning the cut side upward. The material of the spacer is not particularly limited. For example, even if it is a hard material, a wall surface having good adhesion to the first and second lens precursors can be constructed by using a gel agent or an adhesive together. However, as the spacer, a sticky and flexible sheet body as described above is preferable in terms of work. Since the thickness of the spacer matches the thickness of the intermediate layer to be formed, it is an element to be changed depending on what kind of intermediate layer is required. For eyeglass lenses, it is generally about several μm to several mm.
As a means for curing the photosensitive monomer, thermal curing (including dielectric heating by microwaves), photocuring, etc. are assumed.

In the above configuration, the thickness of the first lens precursor is preferably the same throughout. That is, it is preferable that the curve configurations of both molding surfaces of the first and second lens molds are the same. This configuration contributes to the stability of each layer when a sheet body is attached to the surface of the first lens precursor and a third lens mold is further attached.
Moreover, it is preferable that the thickness of an intermediate | middle layer is the same thickness in the whole region. That is, it is preferable that the curve configuration of the surface in contact with the intermediate layer of the first lens precursor and the curve configuration of the surface in contact with the intermediate layer of the second lens precursor are the same. This contributes to setting processing of a predetermined refractive index distribution by ultraviolet irradiation to the intermediate layer thereafter.
In addition, it is possible to set the surface of the first lens precursor that is exposed when one of the first and second lens molds is removed so that the upper surface faces the upper surface. Above preferred.

  Further, in the third means, as in the first means, first, a lens monomer is filled into the first cavity of the mold constituted by the first and second lens molds, and this is cured to be the first. 1 lens precursor is obtained. Next, the adhesive tape is cut along a boundary line between the cured first lens precursor and either the first or second lens mold, and either the first or second lens mold is used. Remove one. (Demold) That is, the first lens precursor is continuously held by either one of the first and second lens molds. As a means for curing the lens monomer, thermal curing (including dielectric heating by microwaves), photocuring or the like is assumed.

Next, the first lens precursor exposed by interposing a ring-shaped spacer with respect to the second lens precursor molded in advance is arranged so as to face. This constitutes a second cavity surrounded by the first and second lens precursors and the spacer. Next, the adjusted photosensitive monomer is filled in the second cavity, and the photosensitive monomer is cured to form a lens having a three-layer structure having an intermediate layer between the first and second lens precursors. A lens can be obtained by removing the other one of the first and second lens molds that has not been removed from the lens having such a configuration.
The definition of the spacer is the same as that of the above means 1.

  In the invention of each of the above claims, in the lens having a three-layer structure in which the intermediate layer is formed by curing the photosensitive epoxy monomer, the lens layer on the side opposite to the power setting side is always the first or first lens layer. Therefore, even if an external force is applied, the lens layer is not easily deformed, and it is not necessary to process the lens layer after molding the lens.

Example 1
Hereinafter, specific Example 1 of the present invention will be described.
1. Lens precursor molding step First, a first lens mold 1 and a second lens mold 2 are prepared. The first and second lens molds 1 and 2 are meniscus glass circular plates made of spherical surfaces having the same curvature on both the front and back surfaces. The back surface 1a of the first lens mold 1 is a curved surface for molding the front surface (object side) of the front lens piece 3 as a first lens precursor to be molded, and the surface of the second lens mold 2 Reference numeral 2a denotes a curved surface for molding the back surface (eyeball side) of the front lens piece 3 to be molded. In the first embodiment, the back surface 1a and the front surface 2a have the same curvature, and the distance between the back surface 1a and the front surface 2a is 0.5 mm.
As shown in FIG. 1, the outer surfaces of both molds 1 and 2 are surrounded by a tape 4 in which the back surface 1a and the front surface 2a of both molds 1 and 2 are arranged to face each other with a predetermined interval and an adhesive surface is formed on one side A first cavity C1 is formed inside. Then, the lens monomer 5 adjusted in the cavity C1 in accordance with a plastic lens molding method is injected using a syringe (not shown) (state of FIG. 2). Then, heat treatment is performed for a predetermined time in accordance with a conventional method, and the lens monomer 5 is cured to produce the front lens piece 3. The produced front lens piece 3 becomes a meniscus transparent plastic lens having a uniform thickness (0.5 mm).
As shown in FIG. 3, in the first embodiment, after the front lens piece 3 is cured, the tape 4 is peeled off, and only the upper first lens mold 1 is removed. The front lens piece 3 is set so that the exposed surface 3a side faces upward.

2. Sheet body sticking process As shown in FIG. 4, the gel sheet 7 is stuck to the exposed surface 3a of the front lens piece 3 so as to cover the entire surface. In Example 1, the gel sheet 7 is made of urethane elastomer and has a thickness of 0.2 mm. Then, as shown in FIG. 5, the first lens mold 1 once removed on the gel sheet 7 is attached so as to cover the gel sheet 7.
3. Second Cavity Configuration Step As shown in FIG. 6, the second lens mold 2 arranged on the lower side in the above is removed from the front lens piece 3 to expose the surface opposite to the exposed surface 3a. Let This is defined as a first molding surface 3b. On the other hand, as shown in FIG. 7, a rear lens piece 8 is prepared as a second lens precursor. The rear lens piece 8 is a meniscus transparent plastic lens, and has a thickness of 10 mm in the first embodiment. The front surface of the rear lens piece 8 is a second molding surface 8a.
An annular spacer 9 is attached near the edge of the second molding surface 8 a of the rear lens piece 8. In the first embodiment, a spacer 9 made of urethane elastomer having a thickness of 0.5 mm is used. Then, as shown in FIG. 8, the front lens piece 3 is placed on the spacer 9 so that the first molding surface 3b of the front lens piece 3 and the second molding surface 8a of the rear lens piece 8 face each other. . In this state, the second cavity C2 surrounded by the first and second molding surfaces 3b and 8a and the spacer 9 is formed. In Example 1, since the first lens mold 1 and the rear lens piece 8 are compressed in the thickness direction by a clip (not shown) from the outside, the first lens mold 1 and the front lens piece 3 are compressed. And the rear lens piece 8 and the like are not separated from the overlapping state.

4). Lens Molding Step As shown in FIG. 9, the epoxy monomer 11 as the photocurable monomer adjusted in the second cavity C <b> 2 is accommodated in the syringe 10, and the needle 10 a of the syringe 10 is inserted from the outer surface of the spacer 9. The monomer 11 is injected through. The needle 10a is pulled out after the monomer 11 is filled in the second cavity C2, but the piercing hole is automatically closed because the spacer 9 has a restoring force. Then, heat treatment is performed for a predetermined time in accordance with a curing method for the photocurable monomer to cure the epoxy monomer 11 to form the intermediate layer 12 as shown in FIG. As a result, the lens 13 having a three-layer structure having the intermediate layer 12 sandwiched between the front lens piece 3 and the rear lens piece 8 is molded. As shown in FIG. 11, the lens 13 is obtained by removing the first lens mold 1 together with the gel sheet 7. The first lens mold 1 can be reused.
5). Post-processing Step The lens 13 is cut into a predetermined size along the cut line shown in FIG. 11 to obtain a round lens. Then, the intermediate layer 12 is irradiated with ultraviolet rays to give a predetermined refractive index distribution.

By configuring in this way, the method of the first embodiment has the following effects.
(1) Conventionally, when a lens having a three-layer structure having such an intermediate layer made of a photosensitive resin is manufactured, in order to reduce the thickness, the lens layer (lens precursor) must be thinned by cutting or grinding. There wasn't. However, if the intermediate layer 12 is formed while always holding the front lens piece 3 so as not to be deformed in this way, the lens 13 is manufactured using a thin lens layer (lens precursor) from the beginning. Therefore, there is no time loss or material loss for processing.
(2) Since the back surface 1a of the first lens mold 1 and the front surface 2a of the second lens mold 2 have the same curve configuration, the layer structure in FIG. 5 is stable, and the first lens mold 1 is displaced. The front lens piece 3 is not deformed.

(Example 2)
Hereinafter, specific Example 2 of the present invention will be described. A description of the same configuration as that of the first embodiment is omitted.
1. Lens precursor molding step First, a first lens mold 1 and a second lens mold 2 are prepared. The configuration of the first and second lens molds 1 and 2 is the same as that of the first embodiment, and the outer periphery is surrounded by the tape 4 as in the first embodiment (FIG. 1). Then, the front lens piece 3 is manufactured in the same process as in the first embodiment (FIG. 2).
Next, the tape 4 is cut along the boundary line between the outer periphery of the front lens piece 3 and the second lens mold 2 and divided into two parts in the vertical direction as shown in FIG. That is, the front lens piece 3 formed by removing only the second lens mold 2 is supported by the tape and is attached to the first lens mold 1.

2. Second Cavity Configuration Step As shown in FIG. 7, a rear lens piece 8 is prepared as a second lens precursor, and an annular shape is provided near the edge of the second molding surface 8 a of the rear lens piece 8. A spacer 9 is attached. The configurations of the rear lens piece 8 and the spacer 9 are the same as those in the first embodiment. Then, as shown in FIG. 13, the front lens piece 3 is placed on the spacer 9 so that the first molding surface 3 b of the front lens piece 3 and the second molding surface 8 a of the rear lens piece 8 face each other. . In this state, the second cavity C2 surrounded by the first and second molding surfaces 3b and 8a and the spacer 9 is formed. In the second embodiment, the first lens mold 1 and the front lens piece 3 are compressed in the thickness direction by a clip (not shown) from the outside of the first lens mold 1 and the rear lens piece 8. And the rear lens piece 8 and the like are not separated from the overlapping state. The tape 4 is peeled off after being sandwiched between clips.

3. Lens molding step As in the first embodiment, the epoxy monomer 11 as the photocurable monomer adjusted in the second cavity C2 is injected through the needle 10a of the syringe 10 from the outer surface of the spacer 9. And the epoxy monomer 11 is hardened like Example 1, and the intermediate | middle layer 12 is shape | molded like FIG. As a result, the lens 13 having a three-layer structure having the intermediate layer 12 sandwiched between the front lens piece 3 and the rear lens piece 8 is molded. Next, the lens 13 is obtained by removing the first lens mold 1 as shown in FIG. The first lens mold 1 can be reused.
5). Post-processing step The same as in Example 1 (FIG. 11).
By configuring in this way, the second embodiment also has the same effects as the first embodiment.

It should be noted that the present invention can be modified and embodied as follows.
In the first embodiment, after the front lens piece 3 is cured, the first lens mold 1 side is demolded. On the contrary, the second lens mold 2 side is demolded. Of course.
In Example 2, after the front lens piece 3 is cured, the second lens mold 2 side is removed, but on the contrary, the first lens mold 1 side is removed. Of course.
In the above embodiment, a clip (not shown) is used as a means for fixing the first lens mold 1, the front lens piece 3, the rear lens piece 8, etc. in an overlapping arrangement, but the tape 4 is used instead of the clip. May be wound.
An adhesive may be interposed between the gel sheet 7 and the gel sheet 7 in order to improve the adhesion between the gel sheet 7 and the first lens mold 1 or the front lens piece 3.
-The shape of the spacer 9 is not limited to the said Example. Since the lens 13 is cut into a predetermined size by a post-processing step, it is sufficient that the spacer 9 can maintain a predetermined thickness and can form the second cavity C2 together with the first and second molding surfaces 3b and 8a.
-Besides, it is free to implement in a mode that does not depart from the gist of the present invention.

Sectional drawing which simplified and showed the state which assembled the 1st and 2nd lens mold in order to produce the front lens piece in the Example of this invention, and formed the inside. Sectional drawing which simplified and showed the state which filled the monomer for lenses in the 1st and 2nd lens mold in the same Example. Sectional drawing which simplified and showed the state which demolded the 1st lens mold from the state by which the monomer for lenses was hardened in FIG. 2, and the front lens piece was shape | molded. Sectional drawing which simplified and showed the state which stuck the gel sheet on the surface of the front side lens piece of the state of FIG. Sectional drawing which simplified and showed the state which stuck the 1st mold for lenses on the gel sheet in the state of FIG. Sectional drawing which simplified and showed the state which removed the 2nd mold for lenses in the state of FIG. Sectional drawing which simplified and showed the state which stuck the spacer on the 2nd shaping | molding surface of the rear lens piece in the same Example. Sectional drawing which simplified and showed the state which mounted the structure which consists of the front side lens of FIG. 6, a sheet | seat, and the 1st lens mold on the 2nd molding surface of FIG. Sectional drawing which simplified and showed the state which is going to inject | pour a monomer in the cavity formed in FIG. Sectional drawing which simplified and showed the state by which the monomer with which it filled in the cavity formed in FIG. 9 hardened | cured, and the intermediate | middle layer was formed. Sectional drawing which simplified and showed the state which removed the 1st lens mold and the gel sheet in FIG. Sectional drawing which simplified and showed the state which cut the tape and divided | segmented up and down in the boundary line of the 2nd lens mold and front lens piece in FIG. Sectional drawing which simplified and showed the state which mounted the upper division body of FIG. 12 on the 2nd shaping | molding surface of FIG. Sectional drawing which simplified and showed the state by which the monomer with which it filled in the cavity formed in FIG. 13 hardened | cured, and the intermediate | middle layer was formed. It is explanatory drawing which briefly demonstrated the manufacturing process of the conventional plastic lens for spectacles, (a) is the state which assembled the 1st and 2nd lens precursor, (b) is the state which shape | molded the intermediate | middle layer, ( c) A state in which the periphery is cut and the upper surface of the second lens precursor is ground.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... 1st and 3rd lens mold, 2 ... 2nd lens mold, 3 ... Front side lens piece as 1st lens precursor, 5 ... Lens monomer, 7 ... Gel sheet as sheet | seat body, 8 ... rear lens piece as first lens precursor, 9 ... spacer, 11 ... photosensitive monomer, 20 ... sensor protective tube as protection member, 29 ... microwave generator, C1 ... first cavity, C2 ... Second cavity.

Claims (4)

A first lens mold having a molding surface for molding one of the front surface and the back surface of the lens, and a second lens mold having a molding surface for molding one of the other. The first lens precursor is filled with the adjusted lens monomer in the first cavity configured by combining the lens molds with the molding surfaces facing each other, and the monomer is cured. The body is molded, and then either the first lens mold or the second lens mold attached to the cured first lens precursor is removed, and the body can be attached to and detached from the exposed first lens precursor surface. A third lens mold having the same lens curve configuration as that of the first or second lens mold removed from the adhesive sheet and a flexible sheet body is attached to the sheet body. The first or second lens mold on the side facing the first lens precursor is removed, and a ring-shaped spacer is formed with respect to the second lens precursor previously molded. The second lens is formed between the first and second lens precursors by arranging the first lens precursor face-to-face with the photosensitive monomer interposed therebetween, and the photosensitive monomer adjusted in the second cavity A method for producing a plastic lens, wherein the photosensitive monomer is cured to form a three-layer lens, and then the sheet body and the third lens mold are removed. The plastic lens manufacturing method according to claim 1, wherein a mold equivalent to the first or second lens mold removed in advance is used as the third lens mold. A first lens mold having a molding surface for molding one of the front surface and the back surface of the lens, and a second lens mold having a molding surface for molding one of the other. The lens monomer adjusted in the first cavity constituted by winding the outer periphery of both molds with an adhesive tape in a state where the molding surfaces of the both lens molds face each other and are spaced apart from each other. And the monomer is cured to mold the first lens precursor, and then the boundary line between the cured first lens precursor and either the first or second lens mold The adhesive tape is incised along the surface to remove either the first lens mold or the second lens mold, and the second lens precursor previously molded into the exposed first lens precursor. A second cavity is formed between the first and second lens precursors by disposing the first lens precursor facing each other with a ring-shaped spacer interposed therebetween, and the second cavity After filling the inside with the adjusted photosensitive monomer, the photosensitive monomer is cured to form a three-layer lens, and then the other first or second lens mold that has not been removed is removed. A method for producing a plastic lens, characterized by comprising: The method for manufacturing a plastic lens according to any one of claims 1 to 3, wherein the spacer is made of an adhesive and flexible sheet.

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