JP2013028080A - Method of manufacturing plastic lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high quality plastic lens that can be used to make glasses show an excellent sense of wearing.SOLUTION: A method for manufacturing the plastic lens contains: injecting plastic lens raw material liquid to the forming die cavity; performing curing reaction of plastic lens raw material liquid in the cavity and obtaining the plastic lens base material having a transferred surface where a mold forming surface shape is transcribed; releasing the plastic lens base material from a forming die; and annealing the plastic lens base material after the release. In the release, the adhered state of the mold forming surface and the transferred surface of the plastic lens base material is maintained by removing one side of two molds that compose the forming die and not removing the other side. The annealing is performed by arranging the plastic lens base material on a mounting table through the mold that is not removed in the release and the forming surface is adhered to the transferred surface of the plastic lens base material.

Description

  The present invention relates to a method for manufacturing a plastic lens, and more particularly to a method for manufacturing a plastic lens capable of providing a high-quality plastic lens in which the generation of astigmatism (astigma) caused by an annealing process is suppressed. It is.

  Examples of a method for obtaining a plastic lens by molding plastic into a lens shape include a casting polymerization method in which a plastic lens raw material liquid is polymerized in a mold. In the casting polymerization method, the lens optical surface is formed by transferring the molding surface shape.

  As the casting polymerization method, two circular molds (upper mold and lower mold) are inserted into an annular gasket, and a plastic lens raw material solution is injected into a cavity (space) formed by the gasket and the upper and lower molds for polymerization. (Refer patent document 1) The method (refer patent document 2) which superpose | polymerizes by inject | pouring a plastic lens raw material liquid into the cavity formed by winding a tape around the surrounding surface of two circular molds is known.

JP 2008-30431 A JP 2007-216665 A

As described above, the shape of the plastic lens polymerized in the cavity formed by surrounding the two circular molds becomes circular. In the present specification and the present invention, unless otherwise specified, the shape is a plan view shape.
However, most of the lenses framed in the spectacle frame when actually manufacturing spectacles have a short meridian direction and a long horizontal direction. Therefore, the actual situation is that the upper and lower ends of the circular plastic lens (lens blanks) obtained by the casting polymerization are cut and discarded. Since the plastic lens raw material liquid used in this discarded part is unnecessary for an actual spectacle lens, in order to reduce the amount of the raw material liquid used and to reduce the manufacturing cost, the part removed at the time of frame insertion Should be as small as possible. From the viewpoint of environmental load, it is desirable to reduce the amount of waste at the time of framing.

  As a means for reducing the amount of waste and the amount of plastic lens raw material used, it is conceivable that the shape of the lens formed by cast polymerization is non-circular. Therefore, it is conceivable to use a non-circular mold to mold the non-circular lens, but it is difficult to accurately align the two non-circular molds.

  In contrast, the applicant of the present application has found that a non-circular lens can be manufactured using a circular mold by, for example, a method of inserting a cylindrical member capable of forming a non-circular cavity between molds. (Japanese Patent Application Nos. 2010-124271, 2010-142275, and 2010-142276).

  According to the above method, it is possible to form a non-circular lens while using a circular mold that is easy to align. However, as a result of studies by the present inventors, it has become clear that, for example, astigmatism (astigma) that is unnecessary for spectacle correction may occur in a non-circular lens manufactured by the above method. Glasses produced using a lens in which astigmatism is significantly generated are inferior in wearing feeling, and thus glasses having good wearing feeling while reducing the amount of waste and the amount of plastic lens raw material used are reduced. In order to provide, it is required to reduce astigmatism in a non-circular lens. Further, even in a circular lens, suppressing the generation of astigmatism is an effective means for providing glasses having a good wearing feeling.

  Under such circumstances, the present invention has been made for the purpose of providing a high-quality plastic lens capable of producing eyeglasses exhibiting a good wearing feeling.

In order to achieve the above object, the present inventors have repeatedly studied the reason why astigmatism occurs in a non-circular lens, and as a result, the annealing process applied to the released lens after cast polymerization is the cause. It came to think that it is. This point will be described in more detail. In a plastic lens manufacturing process by cast polymerization, annealing (heating treatment) is performed on the lens after mold release in order to remove internal distortion generated during polymerization. However, if the lens is not stably held during annealing, the lens may be deformed during annealing heating to promote optical distortion, and the molded lens optical surface may be deformed by transferring the shape of the molded surface. is there. On the other hand, the applicant of the present application disclosed in Japanese Patent Application Laid-Open No. 7-108622 and Japanese Utility Model Laid-Open No. 7-18832 in which a lens is placed on a lens mounting table having a circular opening and the stability of the lens is maintained. It was previously proposed to anneal the lens. However, if the non-circular lens is held by the lens mounting table having the circular opening proposed by the applicant of the present application, it is difficult to ensure the stability of the lens during annealing because the shape does not match. The inventors considered that the instability here is a cause of astigmatism in a non-circular lens. Therefore, as a countermeasure, annealing may be performed using a mounting table having a holding unit corresponding to the shape of the non-circular lens, but this prepares a mounting table having a shape corresponding to each different shape of the non-circular lens. This must increase the cost significantly. On the other hand, Japanese Patent Laid-Open No. 2001-232691 proposes a method of partially supporting the lens surface as a lens holding method during annealing that can also be applied to a non-circular lens, but directly supporting the lens surface. In the method, if the lens softens due to heating during annealing and the shape changes, there is a concern that the support portion is recessed in a concave shape and the surface shape collapses. In addition, the spectacle lens has a wide variety of surface shapes, and there are many lenses having complicated surface shapes such as lenses including aspherical progressive elements. For such a lens surface having a complicated surface shape, it is often difficult to find a portion that can be stably supported. This also applies to the circular lens.
On the other hand, as a result of further earnest studies, the present inventors have not removed one of the two molds constituting the mold at the time of mold release after the casting polymerization, and have removed the lens through the mold that was not removed. It has been found that a high-quality plastic lens in which the occurrence of astigmatism (astigma) is suppressed can be obtained by placing it on the mounting table. Since the shape of the molded surface most closely matches the surface shape of the lens after casting polymerization, if annealing is performed with the transferred surface of the lens and the molded surface forming the transfer surface in close contact, Even if the lens is softened by heating during annealing, the shape transferred to the lens surface is the shape of the molded surface that should be transferred, and the surface accuracy is not reduced. In addition, the lens-supporting surface is a molded surface that has a male and female relationship with the lens surface (transfer surface) and has a shape that is almost the same, so even a lens with a complicated surface shape as described above can be held stably. can do.
The present invention has been completed based on the above findings.

That is, the above object was achieved by the following means.
[1] Injecting a plastic lens raw material liquid into the cavity of a mold having two molds whose molding surfaces face each other at a predetermined interval and a cavity formed by closing the interval,
Obtaining a plastic lens substrate having a transferred surface on which the molding surface shape is transferred by performing a curing reaction of the plastic lens raw material liquid in the cavity,
Releasing the plastic lens substrate from the mold, and
Annealing the plastic lens substrate after release,
A method for producing a plastic lens comprising:
In the mold release, one of the two molds is removed and the other is not removed, and the close contact state between the molding surface and the transferred surface of the plastic lens substrate is maintained, and
The annealing is performed by placing the plastic lens base material on a mounting table via a mold in which the plastic lens base material is not removed in the mold release and the molding surface is in close contact with the transfer surface of the plastic lens base material. The manufacturing method.
[2] At least one of the two molds constituting the mold is a circular mold, and the cavity has a non-circular cross-sectional shape in plan view, whereby a plastic lens base obtained by a curing reaction in the cavity is obtained. The transferred surface of the material is non-circular,
The manufacturing method according to [1], wherein the mold that is not removed in the mold release and is placed on the placement in the annealing is the circular mold.
[3] The manufacturing method according to [2], wherein the mounting table has an opening that opens upward, and the circular mold is held by a holding portion or an opening end surface provided on the inner peripheral surface of the opening.
[4] The manufacturing method according to [3], wherein the opening of the mounting table is a circular opening.

  ADVANTAGE OF THE INVENTION According to this invention, the plastic lens which can produce the spectacles which show favorable wearing feeling by which generation | occurrence | production of the astigmatism (astigma) unnecessary for spectacles correction was suppressed can be provided. Furthermore, according to the present invention, as the plastic lens, a non-circular plastic lens having a shape close to the shape of a lens to be framed as compared with a circular lens can be manufactured.

It is a perspective explanatory drawing of the mounting base for annealing which can be used in one mode of the present invention, and the circular mold and non-circular lens mounted on this. It is sectional drawing (YY sectional drawing in FIG. 1) which shows the state which mounted the non-circular lens via the circular mold on the mounting base for annealing shown in FIG. It is the schematic which shows an example of the cylindrical member inserted | pinched between two circular molds in the shaping | molding die which can be used in this invention. It is sectional drawing which shows an example of the mold and gasket which comprise a part of shaping | molding die which can be used in this invention. It is sectional drawing of the state which has arrange | positioned the cylindrical member shown in FIG. 3 in the cavity shown in FIG. It is the schematic which shows an example of the bottomed mold which comprises the shaping | molding die which can be used in this invention. It is sectional drawing of a bottomed mold shown in FIG. It is the schematic which shows an example of the shaping | molding die which can be used in this invention. It is sectional drawing which shows an example of the bottomed mold which comprises the shaping | molding die which can be used in this invention. It is an example of the top view of the area | region A of a bottomed mold shown in FIG. It is sectional drawing of the shaping | molding die comprised by inserting circular mold in opening of the bottomed mold shown in FIG.

According to the present invention, a plastic lens raw material liquid is injected into the cavity of a mold having two molds whose molding surfaces face each other at a predetermined interval and a cavity formed by closing the interval. To obtain a plastic lens substrate having a transferred surface on which the molding surface shape is transferred by performing a curing reaction of the plastic lens raw material liquid, releasing the plastic lens substrate from the mold, and releasing The present invention relates to a method for manufacturing a plastic lens, including annealing a subsequent plastic lens substrate. In the plastic lens manufacturing method of the present invention, in the mold release, one of the two molds is removed and the other is not removed, and the close contact state between the molding surface and the transferred surface of the plastic lens substrate is maintained, and The annealing is performed by placing the plastic lens base material on the mounting table through a mold in which the molding surface is in close contact with the transfer surface of the plastic lens base material without removing the plastic lens base material in the mold release. According to the method for producing a plastic lens of the present invention, as described above, it is possible to provide a plastic lens in which the generation of astigmatism (astigma) unnecessary for correcting glasses is suppressed. In addition, by manufacturing a non-circular lens as a plastic lens, it is possible to greatly reduce the amount of waste and the amount of plastic lens raw material used when placing the frame.
Hereinafter, the plastic lens manufacturing method of the present invention (hereinafter also referred to as “the manufacturing method of the present invention”) will be described in more detail.

  In the manufacturing method of the present invention, a plastic lens substrate (hereinafter simply referred to as “plastic”) is used by using a mold having two molds whose molding surfaces face each other with a predetermined gap and a cavity formed by closing the gap. Cast polymerization of “lens” or “lens”). Here, a mold for normal casting polymerization, that is, two circular molds are arranged to face each other, and a cavity having a circular cross-sectional shape in plan view (hereinafter referred to as “circular cavity”) is formed between the molds. A circular lens can be obtained by using a mold. On the other hand, in the conventional casting polymerization mold, a non-circular lens cannot be obtained, but it is difficult to accurately align the molds when both of the two molds facing each other are non-circular molds. Therefore, in the present invention, at the time of manufacturing a non-circular lens, at least one of two molds constituting the mold is a circular mold, and a cavity having a non-circular sectional shape in plan view (hereinafter referred to as “non-circular cavity”) is used. It is preferable to use a mold having the same. As such a mold, the mold according to the above patent application can be suitably used, and details thereof will be described later. In the present invention, the sectional shape of the cavity in plan view means not a longitudinal section shown in FIG. 4 and the like described later, but a sectional shape of a transverse section orthogonal to the longitudinal section.

  In the casting polymerization, a plastic lens base material having a transferred surface onto which the shape of the molding surface is transferred can be obtained by performing a curing reaction of the plastic lens raw material liquid in the mold cavity. A circular lens can be obtained with a mold having a circular cavity, and a non-circular cavity can be obtained with a mold having a non-circular cavity. Examples of the shape of the non-circular lens include various shapes other than a circle such as a rounded quadrangle, an ellipse, and a polygon. Since the shape of a general spectacle frame is short in the meridian direction and long in the horizontal direction, a noncircular lens that approximates this shape is preferable from the viewpoint of further reducing the amount of waste, and from this point, a rounded rectangle or ellipse is preferable. The shape is preferable, and a rounded square is more preferable. The length of the minor axis (meridian direction) of the non-circular lens is about 45 to 65 mm, and the length of the major axis (horizontal direction) is about 60 to 75 mm. Therefore, it is preferable. On the other hand, the diameter of the circular lens is usually about 50 to 100 mm. The thickness of the lens to be molded is defined by the depth of the cavity, and is usually about 1 to 30 mm.

  The lens molded using the mold is subjected to annealing after being taken out (released) from the mold. Although this annealing can remove internal distortion generated during the polymerization, as described above, there is a problem that astigmatism (astigma) occurs due to instability of the lens support during annealing. On the other hand, as described above, according to the present invention, one of the two molds constituting the mold is removed at the time of mold release, and the other is not removed, and the molding surface and the transferred surface of the plastic lens substrate are removed. While maintaining the close contact state, annealing is performed by placing the lens to be annealed on the mounting table via a mold whose molding surface is not removed by mold release and in close contact with the transfer surface of the plastic lens substrate. Thus, the above problem can be solved. Hereinafter, the annealing will be described in more detail with reference to the drawings.

  FIG. 1 is a perspective explanatory view of a mounting table 11 for annealing usable in one embodiment of the present invention, and a circular mold 13 and a non-circular lens 14 mounted thereon. FIG. 2 is a cross-sectional view (a YY cross-sectional view in FIG. 1) showing a state in which the non-circular lens 14 is placed on the annealing mounting base 11 shown in FIG. The mounting table 11 in the figure has a circular opening that opens upward, and a holding portion 12 having a tapered holding surface (tapered surface) is provided on the inner peripheral surface of the circular opening. ing. Note that the angle of the tapered surface of the holding portion 12 is set in consideration of the radius of curvature of the surface to be held (convex surface in the drawing) of the circular mold. Moreover, it is preferable that the angle of the said taper surface has performed the thread chamfering from a viewpoint of the contact which arises at the time of handling, safety, etc. Moreover, the annealing stage 11 can have an extraction recess 15. That is, one end of the peripheral wall portion of the annealing table 11 is opened to the circular opening of the mounting table 11, and the other end is positioned at the same height as or below the holding unit 12, so that the inside and outside of the mounting table 11 communicate with each other. A plurality of extraction recesses 15 are provided. There may not be such a recess for extraction, and there may be one or more. Moreover, it is preferable that two take-out recesses are formed at opposite positions on the side wall of the mounting table 11. The shape dimension of the recess for extraction is set to a size that allows human fingers to enter, and allows the circular mold and the non-circular lens to be extracted by the finger. The circular mold 13 is placed on the tapered holding portion 12. The circular mold 13 is placed so that the peripheral surface lower surface 16 is supported by the holding unit 12. This state is shown in the cross-sectional explanatory view (YY) of FIG. In FIG. 2, for the sake of convenience, the extraction recess 15 is not shown.

  The surface opposite to the surface to be held of the circular mold 13 (the concave surface in the figure) is a molding surface, and the shape of one surface of the non-circular lens (surface to be transferred) is determined by casting polymerization. It is formed by transferring the surface shape of the molding surface. In the present invention, since one mold is not removed from the lens at the time of releasing, the non-circular lens 14 is formed on the molding surface of the circular mold 13 as shown in FIGS. Are arranged in close contact with each other. If the non-circular lens is arranged on the mounting table via the circular mold in this way, it is not necessary to prepare a mounting table for each shape of the non-circular lens, and the molding surface and the transferred surface are in a relationship of male and female. Since the shapes are the same, it becomes possible to stably hold a non-circular lens, which was difficult with only a conventional annular mounting table. Furthermore, both the circular lens and the non-circular lens have a complicated surface shape. The lens can be held stably. In addition, as described above, even if the lens is softened by heating during annealing, the shape transferred by this softening is the shape of the molded surface that should be transferred, so that the surface accuracy is reduced. Absent. Thus, according to the present invention, a high-quality plastic lens in which the generation of astigmatism due to annealing is suppressed can be obtained. Further, since the lens to be annealed is disposed on the mounting table via the mold, contamination of the lens surface can be prevented as compared with the case where the lens is directly mounted on the mounting table. Annealing can be performed by placing a known heating furnace annealing target lens heated to a predetermined ambient temperature together with the mounting table and the mold in the above-described mounting state. The mold placed in close contact with the lens to be annealed and placed on the mounting table is preferably made of a material having heat resistance that does not easily soften and deform during annealing. Since a mold used for normal casting polymerization such as a glass mold has heat resistance that can withstand the heat during polymerization, there is usually no risk of deformation during annealing.

  In the embodiment described above with reference to the drawings, the circular mold is supported by the tapered holding portion provided on the entire inner peripheral surface of the circular opening of the annealing stage, but the present invention is limited to this embodiment. It is not something. For example, it is possible to provide holding portions as a plurality of protrusions on the inner peripheral surface of the mounting table circular opening. Or it is also possible to hold | maintain the non-molding surface peripheral edge part of a circular mold by the opening end surface of a circular opening part by making the opening diameter of the circular opening part of a mounting base smaller than the external shape of a circular mold. In the figure, a non-circular lens is shown as a lens to be annealed. However, as described above, it is difficult to stably hold a non-circular lens during annealing. In this respect, the stability of the lens during annealing is reduced. The production method of the present invention that can be ensured is particularly effective in an embodiment in which the lens to be annealed is a non-circular lens. However, in the present invention, the lens to be annealed may be a circular lens, and a circular lens with reduced astigmatism (astigma) can be obtained by applying the present invention. The annealing stage used in the present invention is not necessarily limited to the one having a circular opening, but the lens stage that has been conventionally used can be used as it is or after being appropriately modified. The use of a mounting table with a circular opening is advantageous.

  The annealing conditions are determined by the material of the plastic lens to be annealed, the polymerization conditions, the film forming conditions, and the like. As an example, for polyurethane lenses, for example, annealing is usually performed at 20 to 130 ° C. for 30 minutes to A heat treatment for about 12 hours is performed.

  The annealing target lens may be a finish lens (lens blank optically finished on both sides) or a semi-finished lens (lens blank optically finished on only one surface). The semi-finished lens has an optically finished surface, and the back surface is polished so as to have a desired lens power according to the lens prescription value. The plastic lens having both surfaces optically finished is trimmed into a frame shape of a spectacle frame at a spectacle store or by a manufacturer who has received an order from the spectacle store, and then beveled. A functional film for imparting desired performances such as an antireflection film and a water repellent film before and after that can be formed on the lens by a known method, if necessary. Glasses are completed by fitting a lens, which is rimmed and has a functional film as necessary, into a spectacle frame. Here, if the plastic lens manufactured according to the present invention is a non-circular lens, the amount of the part removed and discarded as an unnecessary part in the edging process can be greatly reduced as compared with the circular lens.

  Next, a mold that can mold a non-circular lens by cast polymerization will be described.

  One aspect of the mold includes two circular molds opposed to each other with a predetermined interval, a cylindrical member sandwiched between the intervals, and surrounding the peripheral surfaces of the two molds and the cylindrical member, so that the mold and the cylinder are surrounded. And a sealing member for fixing the sandwiched state with the member (hereinafter referred to as “molding die A”). In the mold A, the cylindrical member has a through-hole having a non-circular cross-sectional shape inside, and the through-hole is sealed with the two molds to form a plastic lens raw material liquid injection cavity. . Since the mold A has a cavity formed by sealing a non-circular through hole, a non-circular plastic lens can be obtained by performing a curing reaction of the plastic lens raw material liquid in the cavity. .

3 is a schematic diagram showing an example of a cylindrical member sandwiched between two circular molds in the mold A (the left diagram in FIG. 3 is a plan view, and the right diagram in FIG. 3 is a perspective view). FIG. 3 shows the cylindrical member 1 having the through-hole 2 having a rounded quadrangular cross-sectional shape, but the cross-sectional shape of the through-hole is not limited to the rounded quadrangular shape, but is illustrated as a non-circular lens shape. It can be in various shapes. The thickness of the lens to be molded is defined by the height of the through hole. Therefore, the height of the through hole may be determined according to the desired lens thickness. Moreover, what is necessary is just to determine the shape of the cylindrical part 4 surrounding the said through-hole according to the shape of the mold to be used, and a sealing member so that it can surround with a sealing member with two molds. For example, when an annular gasket is used as the sealing member, the outer diameter of the cylindrical portion may be determined so as to substantially match the inner diameter of the opening portion of the gasket into which the cylindrical member is inserted.
Moreover, the cylindrical member 1 shown in FIG. 3 has the notch 3 in a side surface peripheral part. This notch forms a part of the flow path of the plastic lens raw material liquid. This point will be described later.

  The cylindrical member can be usually obtained by molding a thermoplastic resin used for manufacturing a gasket by a known molding method such as injection molding. The notch can be formed by cutting the peripheral edge of the side surface with a cutter or the like. As will be described later, an opening may be provided on the side surface instead of the notch, and the opening can be formed by making a hole in the side surface by a known opening means of a cutter or a punch.

As the molding die A, a molding die used in normal casting polymerization can be used without any limitation except that the cylindrical member is sandwiched between two molds. That is, the mold A can be configured by disposing the cylindrical member in the cavity of the mold used in normal casting polymerization. Thus, the ability to use a conventionally used mold is advantageous because a non-circular lens can be manufactured without significant changes in the manufacturing process.
For example, as shown in FIG. 4, the mold used in normal casting polymerization is a circular first mold 21 which is a concave mold having a molding surface on the concave side to form the front surface (convex surface) of the lens. In order to form the rear surface (concave surface) of the lens, a circular second mold 22 having a molding surface on the convex surface side is provided, and an annular gasket 23 surrounds the peripheral surfaces of both molds to form a circular cavity 24 therein. Yes. The first mold and the second mold have a non-transfer surface (non-use surface 27) that can be handled by a manufacturing jig and a transfer surface (use surface 26) for transferring the optical surface of the lens. The use surface 26 is a surface for transferring the optical surface shape and surface state of the lens. In this mold, the plastic lens raw material liquid injected from the injection port 25 is introduced into the cavity 24 from the injection port 28 provided on the side surface of the gasket 23, and a curing reaction is performed in the cavity 24. Therefore, the obtained molded body is circular like the cavity 24. When manufacturing a circular lens in this invention, the shaping | molding die of the said structure can be used. Alternatively, as described in Patent Document 2 (Japanese Patent Application Laid-Open No. 2007-216665), a plastic lens raw material liquid is injected into a circular cavity formed by winding a tape around the peripheral surfaces of two circular molds to form a circular lens. It is also possible to obtain

  On the other hand, in the mold A, a cylindrical member is placed in the cavity 24, whereby the plastic lens raw material liquid injection cavity 2 is formed. Since the plastic lens raw material liquid injection cavity has a non-circular shape, a molded body obtained by performing a curing reaction therein also has a non-circular shape.

  FIG. 5 is a cross-sectional view showing a state where the cylindrical member shown in FIG. 3 is arranged in the cavity shown in FIG. 5 is a cross-sectional view taken along the line YY of FIG. 3 left, and the right view of FIG. 5 is a cross-sectional view taken along the line XX of FIG. 3 left.

  As shown in the right figure of FIG. 5, the plastic lens raw material liquid is connected to the plastic lens raw material liquid injection cavity 2 by communicating the inlet 28 provided on the side surface of the gasket and the notch 23 provided on the peripheral edge of the side surface of the cylindrical member. Is formed. It is possible to form a flow path by forming an opening on the side surface of the cylindrical member instead of the notch and communicating the opening and the injection port 28, but from the viewpoint of easy alignment, It is preferable to form a flow path by providing a cutout in the cylindrical member. In addition, forming the flow path by communicating the cutout or opening of the cylindrical member and the inlet of the gasket as described above is advantageous in facilitating the positioning of the gasket and the cylindrical member.

  In the embodiment described above, an annular gasket is used as a sealing member for fixing the sandwiched state between the mold and the cylindrical member by surrounding the periphery of the two molds and the cylindrical member. Instead, an adhesive tape can be used as a sealing member.

  Other forms of the mold include a bottomed mold having a circular outer shape and having a recess that is open on one side and closed on the other, a circular mold that closes the open end of the bottomed mold, and the two And a sealing member that fixes the lid closed state by surrounding the periphery of the mold (hereinafter referred to as “molding die B”). In the mold B, the concave portion of the bottomed mold is closed with a circular mold, whereby a plastic lens raw material liquid injection cavity is formed in the bottomed mold. In conventional casting polymerization, plastic lenses are polymerized in a cavity formed by surrounding two circular molds, so that the lenses that are necessarily formed are limited to circular lenses. On the other hand, in the mold B, since the cavity for injecting the plastic lens raw material liquid is formed by closing the concave portion of the bottomed mold with a circular mold, the shape of the lens to be molded is determined by the shape of the concave portion. . Therefore, a non-circular lens can be molded by designing the concave portion to have a non-circular cross-sectional shape. Even if the shape of the concave portion is non-circular, the bottomed mold is easy to align with the other circular mold because the outer shape is circular.

  FIG. 6 is a schematic view showing an example of a bottomed mold constituting the mold B (the left diagram in FIG. 6 is a plan view, and the right diagram in FIG. 6 is a perspective view). FIG. 6 shows the bottomed mold 31 having the concave portion 32 having a rounded square cross section, but the cross sectional shape of the concave portion is not limited to the rounded square, and various examples exemplified as the shape of the non-circular lens. The shape can be

The thickness of the lens to be molded is defined by the height of the inner side surface of the recess. Therefore, the height of the recess may be determined according to the desired lens thickness. Further, the shape of the cylindrical portion 34 surrounding the concave portion may be determined according to the shape of the other mold and the sealing member so that it can be surrounded by the sealing member together with the other circular mold. For example, when an annular gasket is used as the sealing member, the outer diameter of the cylindrical portion may be determined so as to substantially match the inner diameter of the opening portion of the gasket into which the cylindrical member is inserted.
Also, the bottomed mold 31 shown in FIG. This notch forms a part of the flow path of the plastic lens raw material liquid. This point will be described later.

  FIG. 7 is a cross-sectional view of the bottomed mold shown in FIG. 7 is a cross-sectional view taken along line YY in FIG. 6 and the lower view in FIG. 7 is a cross-sectional view taken along line XX in FIG. The opening end surface 35 of the bottomed mold shown in FIG. 7 is a contact surface with the circular mold. The opening end surface may have a curved surface or an inclined shape according to the surface shape of the abutting circular mold. Thereby, the lid closed state with the circular mold can be stabilized. Moreover, in order to improve the stability of the lid closed state with the circular mold, a flange portion can be formed on the opening end surface of the bottomed mold.

  The bottomed mold may be made of metal or resin. From the viewpoint of easy removal of the molded lens, the bottomed mold is preferably made of resin. The resin-made bottomed mold can be usually obtained by molding a thermoplastic resin used for manufacturing a gasket by a known molding method such as injection molding. Here, a bottomed mold having a molding surface on which an optical surface can be formed by molding a bottomed mold using a mold whose surface is transferred to the inner bottom surface 32 'of the bottomed mold. Can be obtained. By using such a bottomed mold, the surface onto which the inner bottom surface of the bottomed mold is transferred can be used as the optical surface of the lens as it is without polishing or the like. The notch can be formed by cutting the peripheral edge of the bottomed mold side surface with a cutter or the like. As will be described later, an opening may be provided on the side surface instead of the notch, and the opening can be formed by making a hole in the side surface by a known opening means of a cutter or a punch.

  The mold B can be constructed by replacing the upper mold or the lower mold of the mold used in normal casting polymerization with the above-mentioned bottomed mold. Thus, the ability to configure the mold without greatly changing the configuration of the mold conventionally used is advantageous in that it does not require a significant change in the manufacturing process. The conventionally used mold is as described above with reference to FIG. The mold B can be configured by replacing the first mold or the second mold shown in FIG. 4 with a bottomed mold. As an example, FIG. 8 shows a cross-sectional view of a mold configured by replacing the second mold of the mold shown in FIG. 4 with a bottomed mold shown in FIG. 8 is a cross-sectional view taken along line YY in FIG. 6 and FIG. 8 is a cross-sectional view taken along line XX in FIG. In the mold shown in FIG. 8, the concave portion 32 closed by the first mold 21 closing the opening end of the bottomed mold 31 is a plastic lens raw material liquid injection cavity. Therefore, since the molded product obtained by performing the curing reaction in this is non-circular like the concave portion, a non-circular lens can be obtained. In the present invention, “lid closing” means closing the space by covering the open space.

  As shown in the lower diagram of FIG. 8, the plastic lens raw material liquid is introduced into the plastic lens raw material liquid injection cavity 32 by communicating the injection port 28 provided on the side surface of the gasket with the notch 33 provided on the peripheral edge of the side surface of the bottomed mold. Is formed. It is possible to form a flow path by forming an opening on the side surface of the bottomed mold instead of the notch and communicating the opening and the injection port 28, but from the viewpoint of easy alignment It is preferable to form a flow path by providing a notch in the bottomed mold. In addition, forming the flow path by communicating the notched or opening of the bottomed mold with the inlet of the gasket as described above is advantageous for facilitating the positioning of the gasket and the bottomed mold. In addition, the holding part 39 can be provided in a gasket inner peripheral surface as shown in FIG. This holding part 39 is for abutting the peripheral part of the bottomed mold and positioning and holding the bottomed mold. Can do.

  In the embodiment described above, an annular gasket is used as a sealing member for fixing the closed state of the mold by surrounding the periphery of the two molds. Can also be used as a sealing member.

  Still another embodiment of the mold includes a bottomed first mold (hereinafter also referred to as a “bottomed mold”) having a recess that is open on one side and closed on the other, and is inserted into the opening of the bottomed mold. A mold having a circular second mold (hereinafter referred to as “mold C”). In the mold C, the second mold is inserted into an opening of the first mold, whereby the first mold The plastic mold raw material liquid injection cavity is formed by closing the recess of the first mold, and the first mold has an injection port for introducing the plastic lens raw material liquid into the cavity on the side surface. By injecting the plastic lens raw material liquid into the cavity through the inlet, the plastic lens can be polymerized in the cavity. The concave portion of the first mold has a non-circular cross-sectional shape, so that the plastic lens raw material liquid injection cavity also has a non-circular cross-sectional shape. A non-circular plastic lens can be obtained.

  FIG. 9 is a cross-sectional view showing an example of a bottomed mold constituting the mold C. As shown in FIG. The bottomed mold 41 shown in FIG. 9 has a bottomed shape having a recess 42 that is open on one side and closed on the other side. It is preferable to provide a holding part (step part) 44 for positioning and holding the second mold that is inserted into the opening of the bottomed mold, inside the concave part 42. The upper end surface 44 ′ of the holding portion 44 serves as a contact surface with the second mold. By making the outer shape of the upper end surface 44 ′ substantially coincide with the outer shape of the second mold, the second mold can be stably positioned and held. The outer shape of the upper end surface 44 'is circular in order to position and hold the circular mold.

  FIG. 10 is an example of a plan view of a region A of the bottomed mold shown in FIG. As described above, the outer shape of the upper end surface 44 'of the holding portion 44 is circular as shown in FIG. On the other hand, the cross-sectional shape of the portion that is closed by the second mold in the recess 42 to form the cavity is circular as shown in the right figure of FIG. 10, but a circular lens is obtained, but as shown in the left figure of FIG. A non-circular lens can be obtained by making it non-circular. In the embodiment shown in the left diagram of FIG. 10, the cross-sectional shape of the portion that is closed by the second mold in the concave portion 42 to form the cavity is a rounded square, but is not limited to this, and is exemplified as the shape of a non-circular lens. Various shapes. The thickness of the lens to be molded is defined by the height of the portion of the recess that is closed by the second mold. Therefore, the height of the portion of the recess that is closed by the second mold may be determined according to the desired lens thickness.

  A bottomed mold 41 shown in FIG. 10 has an injection port 43 on a side surface. The plastic lens raw material liquid is introduced into the cavity through the injection port 43.

  FIG. 11 is a cross-sectional view of a mold 51 configured by inserting a circular second mold 45 into the opening of the bottomed mold 41 shown in FIG. 9. As the second mold 45, a circular mold used for normal casting polymerization such as a glass mold can be used. The second mold 45 is positioned and held by contacting the upper end surface 44 ′ of the holding portion 44 of the tangible mold 41. Thereby, a plastic lens raw material liquid injection cavity 42 ′ is formed as a closed space closed by the second mold.

  The bottomed mold may be made of metal or resin. From the viewpoint of holding the second mold fitted in the opening and taking out the molded lens, the bottomed mold is preferably made of resin. The resin-made bottomed mold can be usually obtained by molding a thermoplastic resin used for manufacturing a gasket by a known molding method such as injection molding. Here, a bottomed mold having a molding surface capable of forming an optical surface is obtained by molding the bottomed mold using a mold having a mirror polished surface on the surface transferred to the inner bottom surface of the bottomed mold. be able to. By using such a bottomed mold, the surface onto which the inner bottom surface of the bottomed mold is transferred can be used as the optical surface of the lens as it is without polishing or the like. The side injection port may be formed at the time of molding such as injection molding, or may be formed by forming a hole in the side surface by a known opening means of a cutter or a drilling machine after molding. In order to facilitate the introduction of the plastic lens raw material liquid, it is preferable to provide the bottomed mold with a funnel-shaped injection port portion 46 communicating with the injection port 43 as shown in FIG. The inlet 46 may be formed at the time of molding such as injection molding, or may be molded as a separate member and attached with an adhesive or the like.

In the present invention, a non-circular lens can be obtained by using a mold having a non-circular cavity such as the molds A to C described above. In addition, as described above, a circular lens can be obtained by using a mold having a circular cavity for normal casting polymerization.
The plastic lens raw material liquid (hereinafter also referred to as “lens raw material liquid”) to be injected into the cavity contains a curable component and is a raw material monomer or oligomer of various polymers that usually constitute a plastic lens substrate for spectacle lenses. And / or a prepolymer, and a mixture of two or more monomers to form a copolymer. The curable component may be a thermosetting component or a photocurable component, but in the casting polymerization, a thermosetting component is usually used. If necessary, a catalyst selected according to the kind of monomer can be added to the lens raw material liquid. The lens raw material liquid may also contain various commonly used additives.

  Specific examples of the lens raw material liquid include, for example, a copolymer of methyl methacrylate and one or more other monomers, diethylene glycol bisallyl carbonate resin (CR-39), diethylene glycol bisallyl carbonate, and one or more other monomers. Copolymer, polyurethane and polyurea copolymer, polycarbonate, polystyrene, polyvinyl chloride, unsaturated polyester, polyethylene terephthalate, polyurethane, polythiourethane, sulfide resin using ene-thiol reaction, vinyl polymer containing sulfur The raw material liquid which can superpose | polymerize etc. is mentioned.

  The mold release after cast polymerization can be performed in the same manner as or in accordance with the mold release process in normal cast polymerization except that one of the two molds is not removed. However, if annealing is performed in the mold without releasing after polymerization, the internal distortion in the lens cannot be removed by annealing due to deformation (for example, shrinkage) of the mold due to temperature change. Rather, distortion may be promoted, so it is essential to remove one of the molds. Mold components other than one mold, for example, the sealing member such as the gasket described above and the cylindrical member may or may not be removed at the time of mold release, but are preferably removed. This is because the smaller the number of members in close contact with the lens, the more effectively the internal distortion of the lens can be removed by annealing. From this point, for example, when the mold shown in FIG. 4 is used, it is preferable to remove only the first mold 21 or the second mold 22 and remove the other mold and the gasket 23. For the mold A, the circular mold 21 or 22 in FIG. 5 is preferably used. For the mold B, the circular mold 21 in FIG. The mold that has not been removed at the time of mold release is peeled off from the lens surface after the annealing is completed.

  EXAMPLES The present invention will be further described below with reference to examples, but the present invention is not limited to the embodiments shown in the examples.

[Example 1]
1. Production of mold C (1) Molding of bottomed mold Using polyethylene elastomer (Excellen FX, manufactured by Sumitomo Chemical Co., Ltd.) which is an olefinic thermoplastic resin, the cross-sectional shape of the part from the inner bottom surface to the upper edge of the stepped portion is A bottomed mold having a rounded quadrangle (short diameter 62 mm, long diameter 73 mm, height 14 mm from the inner bottom surface to the upper edge) and a round shape with a stepped portion having a diameter of about 80 mm is formed by injection molding. Obtained. As the mold for forming the bottomed mold, a mold in which the surface transferred to the inner bottom surface of the bottomed mold concave portion is a concave surface subjected to mirror polishing. By using this mold, a bottomed mold was formed in which the inner bottom surface of the recess was a convex molding surface capable of forming an optical surface.
After forming the injection port with a cutter on the side of the molded bottomed mold, the bottomed mold is connected so that the injection port formed separately by injection molding communicates with the injection port on the side of the bottomed mold. Attached to the side with an adhesive.
Through the above steps, a bottomed mold having the shape shown in FIG. 11 was obtained.

(2) Mold assembly As shown in FIG. 11, a circular glass mold having a concave molding surface is inserted into the opening of the bottomed mold obtained in (1) above to form a convex surface. The mold shown was assembled.

2. Molding of plastic lens After placing the molding die obtained in (2) so that the injection port portion of the bottomed mold faces vertically upward, the raw material liquid of diethylene glycol bisallyl carbonate resin (CR-39) is injected from the injection port portion. Were introduced into a plastic lens raw material liquid injection cavity formed by closing the recess with a circular mold, and after the cavity was filled, a curing reaction was performed according to a predetermined polymerization program. After completion of the curing reaction, other mold components were removed (released) from the lens, leaving only the circular mold. The shape of the lens after mold release was the same shape as the cavity, that is, a rounded rectangle with a minor axis 62 mm and a major axis 73 mm. That is, a non-circular lens could be obtained. The thickness of the obtained lens was the same as the height from the inner bottom surface of the recess to the upper edge.

3. Annealing 2. As shown in FIG. 2, the lens after the mold release is placed on the mounting table as shown in FIG. 2, while the transfer surface of the lens is in close contact with the molding surface of the circular mold that was not removed during the mold release. Arranged through. In this state, the lens was introduced into a heating furnace and annealed at 20 to 115 ° C. After annealing, the circular mold was peeled off from the convex surface of the lens and removed to obtain an annealed plastic lens.

[Comparative Example 1]
In the mold release, all the components of the mold were removed from the lens, and a plastic lens was obtained in the same manner as in Example 1 except that the non-circular lens was directly placed on the mounting table without using a circular mold during annealing. . The non-circular lens was in contact with the holding portion of the mounting table at both end surfaces on the long diameter side, but was not in contact with the holding portion at both end surfaces on the short diameter side.

  The plastic lens obtained in Example 1 was applied to the lens rest of a lens meter, and the astigma at the distance refractive power measurement reference point was measured, which was -0.040D. Although the lens meter used in the present embodiment is a transmission type, astigma can also be calculated by analyzing the surface refractive power from the measurement result of the reflective surface refractive power device or the shape measuring device. On the other hand, when the stigma of the plastic lens obtained in Comparative Example 1 was measured by the same method, it was -0.30D.

For product lenses, the standard for determining stigma is usually within ± 0.045D.
While the stigma of the lens obtained in Comparative Example 1 was out of the standard, Example 1 was able to obtain a lens within the standard. The reason why the stigma was noticeably generated in Comparative Example 1 is considered to be that the non-circular lens was annealed in an unstable holding state. On the other hand, in Example 1, as described above, it was possible to suppress the generation of stigma unnecessary for correcting the spectacle lens. This is considered to be because annealing was performed in a state where the non-circular lens was stably held on the circular mold. By using such a lens, it is possible to provide eyeglasses with excellent wearing feeling. The non-circular lens obtained in Example 1 is the same as Example 1 except that the cross-sectional shape of the portion from the inner bottom surface of the bottomed mold to the upper edge of the stepped portion is changed to a circle (diameter 75 mm). The volume is about 35% less than a circular lens obtained by making a mold and molding a plastic lens. Therefore, the amount of plastic lens raw material used to obtain a single lens can be reduced by the small volume, and the amount removed and discarded in the edging process for frame insertion is reduced accordingly. can do.

[Example 2]
1. Fabrication of mold A (1) Molding of cylindrical member Using polyethylene elastomer (Excellen FX, manufactured by Sumitomo Chemical Co., Ltd.) which is an olefinic thermoplastic resin, the cross-sectional shape is a rounded square (minor axis 52 mm, major axis 72 mm) A cylindrical member (outer diameter 81.5 mm, height 17.5 mm) having holes was obtained by injection molding.
A notch was formed by a cutter at the peripheral edge of the side surface of the formed cylindrical member.
The cylindrical member having the shape shown in FIG. 3 was obtained through the above steps.

(2) Assembly of molding die The cylindrical member obtained in the above (1) was inserted into an annular gasket made of the same polyethylene elastomer as described above. At this time, the gasket was positioned so that the inlet on the side of the gasket and the notch coincided. Thereafter, two circular glass molds were fitted into the opening of the gasket, thereby assembling a mold having a sectional view shown in FIG.

2. Molding of plastic lens After the molding die obtained in (2) is placed so that the inlet of the gasket faces vertically upward, the raw material liquid of diethylene glycol bisallyl carbonate resin (CR-39) is passed through the cylindrical member through-hole from the inlet. It was introduced into a plastic lens raw material liquid injection cavity formed by sealing with two molds, and after the cavity was filled, a curing reaction was performed according to a predetermined polymerization program. After completion of the curing reaction, the other mold components were removed (released) from the lens, leaving only the first mold 21 shown in FIG. The shape of the lens after mold release was the same shape as the through hole of the cylindrical member, that is, a rounded rectangle with a minor axis of 52 mm and a major axis of 72 mm. That is, a non-circular lens could be obtained. The thickness of the obtained lens was the same as the height of the cylindrical member. By removing unnecessary portions from the non-circular lens according to the frame shape of the spectacle frame and placing it in the spectacle frame, the spectacles can be completed.
For example, a circular lens formed by a molding die in which two circular molds are fitted and assembled in the gasket has a diameter of about 80 mm when the gasket is taken out. Compared to this circular lens, the volume of the non-circular lens is about 35% less. Therefore, the amount of plastic lens raw material used to obtain a single lens can be reduced by the small volume, and the amount removed and discarded in the edging process for frame insertion is reduced accordingly. can do.

3. Annealing 2. As shown in FIG. 2, the lens after the mold release is placed on the mounting table as shown in FIG. 2, while the transfer surface of the lens is in close contact with the molding surface of the circular mold that was not removed during the mold release. Arranged through. In this state, the lens was introduced into a heating furnace and annealed at 20 to 115 ° C.

[Example 3]
1. Production of mold B (1) Molding of bottomed mold Using polyethylene elastomer (Exelen FX, manufactured by Sumitomo Chemical Co., Ltd.), which is an olefinic thermoplastic resin, a recess (minor axis 62 mm, major axis 73 mm) having a rounded square cross section. A bottomed mold (outer diameter: 81.5 mm, height: 23 mm) having a circular outer shape having an inner side surface height of 18 mm was obtained by injection molding. As the mold for forming the bottomed mold, a mold in which the surface transferred to the inner bottom surface of the bottomed mold concave portion is a concave surface subjected to mirror polishing. By using this mold, a bottomed mold was formed in which the inner bottom surface of the recess was a convex molding surface capable of forming an optical surface.
A notch was formed by a cutter at the peripheral edge of the side surface of the molded bottomed mold.
Through the above steps, a bottomed mold having the shape shown in FIG. 6 was obtained.

(2) Assembly of mold The bottomed mold obtained in (1) above was inserted into an annular gasket made of the same polyethylene elastomer as described above. At this time, the gasket was positioned so that the inlet on the side of the gasket and the notch of the bottomed mold coincided. Thereafter, a circular glass mold having a concave molding surface was fitted into the opening of the gasket so as to form a convex surface, thereby assembling a molding die having a sectional view shown in FIG.

2. Molding of plastic lens After the molding die obtained in (2) is arranged so that the inlet part of the gasket faces vertically upward, the raw material liquid of diethylene glycol bisallyl carbonate resin (CR-39) is poured from the inlet part into the concave part of the bottomed mold. Was introduced into a plastic lens raw material liquid injection cavity formed by closing the lid with a circular mold. After the cavity was filled, a curing reaction was performed according to a predetermined polymerization program. After completion of the curing reaction, the other mold components were removed (released) from the lens, leaving only the first mold 21 shown in FIG. The shape of the lens after mold release was the same shape as the concave portion of the bottomed mold, that is, a rounded square with a minor axis of 62 mm and a major axis of 73 mm. That is, a non-circular lens could be obtained. The thickness of the obtained lens was the same as the height of the inner side surface of the recess.

  The non-circular lens obtained in Example 3 was prepared by forming a mold and molding a plastic lens in the same manner as in Example 3 except that the cross-sectional shape of the concave portion of the bottomed mold was changed to a circle (diameter 75 mm). The volume is about 35% less than the obtained circular lens. Therefore, the amount of plastic lens raw material used to obtain a single lens can be reduced by the small volume, and the amount removed and discarded in the edging process for frame insertion is reduced accordingly. can do.

3. Annealing 2. As shown in FIG. 2, the lens after the mold release is placed on the mounting table as shown in FIG. 2, while the transfer surface of the lens is in close contact with the molding surface of the circular mold that was not removed during the mold release. Arranged through. In this state, the lens was introduced into a heating furnace and annealed at 20 to 115 ° C.

  The plastic lenses obtained in Examples 2 and 3 were applied to the lens abutment of a lens meter, and astigma was measured at a distance refractive power measurement reference point. Both were standards for determining the stigma of a normal product lens. It was within ± 0.045D, and it was confirmed that it was possible to suppress the occurrence of stigma unnecessary for correction of spectacle lenses in non-circular lenses.

  The present invention is useful in the field of manufacturing eyeglass lenses.

Claims (4)

Injecting a plastic lens raw material liquid into the cavity of a mold having two molds whose molding surfaces face each other at a predetermined interval and a cavity formed by closing the interval;
Obtaining a plastic lens substrate having a transferred surface on which the molding surface shape is transferred by performing a curing reaction of the plastic lens raw material liquid in the cavity,
Releasing the plastic lens substrate from the mold, and
Annealing the plastic lens substrate after release,
A method for producing a plastic lens comprising:
In the mold release, one of the two molds is removed and the other is not removed, and the close contact state between the molding surface and the transferred surface of the plastic lens substrate is maintained, and
The annealing is performed by placing the plastic lens base material on a mounting table via a mold in which the plastic lens base material is not removed in the mold release and the molding surface is in close contact with the transfer surface of the plastic lens base material. The manufacturing method. At least one of the two molds constituting the mold is a circular mold, and the cavity has a non-circular shape in plan view in cross section, and thereby the plastic lens base material obtained by a curing reaction in the cavity. The transfer surface is non-circular,
The manufacturing method according to claim 1, wherein the mold which is not removed in the mold release and is placed on the placement in the annealing is the circular mold. The manufacturing method according to claim 2, wherein the mounting table has an opening that opens upward, and the circular mold is held by a holding portion or an opening end surface provided on the inner peripheral surface of the opening. The manufacturing method according to claim 3, wherein the opening of the mounting table is a circular opening.