JP2016191785A - Polarizing plastic lens and method for producing the lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-quality polarizing plastic lens by insert molding of filling a polarizing sheet into a molding tool.SOLUTION: A polarizing sheet S is filled into a molding tool 50 so that the direction of filling resin is not perpendicular to a polarizing axis A of the polarizing sheet S, and insert molding is conducted so that the lens body can be formed integrally with the filled polarizing sheet S.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a polarizing plastic lens that can be manufactured with high quality and a manufacturing method thereof.

  Conventionally, some plastic lenses for spectacles are manufactured by an injection molding method using a thermoplastic resin such as polycarbonate resin or methacrylic resin. According to the injection molding method, a plastic lens having a complicated optical surface shape such as a progressive power lens can be molded with high accuracy by transferring the cavity shape of the molding die.

  Further, in manufacturing a functional lens such as a polarizing lens by an injection molding method, it is known to insert-mold a functional sheet such as a polarizing sheet loaded in a molding die in accordance with a desired function ( For example, see Patent Document 1).

JP 2006-47586 A

  By the way, in patent document 1, it is going to manufacture a polarizing plastic lens with an aspherical surface by bending a polarizing sheet according to the curved surface shape of the surface of the polarizing plastic lens with a grade which should be manufactured.

  However, it is not easy to bend the polarizing sheet to finish it into an aspheric surface that matches the lens shape while suppressing distortion of the curved surface. For this reason, in Patent Document 1, a first bending process is performed on the polarizing sheet to form a curved intermediate processed product having a smaller degree of bending than the final product, and the second processed product is formed on the intermediate processed product. Bending is performed to finish the final product having a predetermined aspherical curved surface, and an unreasonable force is not applied to the polarizing sheet by the stepwise bending.

  On the other hand, the polarizing sheet is bent so that it has a curved surface that approximates the molding surface, and the polarizing sheet is deformed to follow the molding surface by the heat and filling pressure of the resin during injection molding, and integrated with this Even if the lens body is molded, a polarizing plastic lens having a desired optical surface shape can be manufactured.

  However, according to the study by the present inventors, when the polarizing plastic lens is manufactured in this way, it is manufactured when the curve of the bent polarizing sheet is a deep curve smaller than the curvature of the molding surface. It has been found that “wrinkles” that are poor in appearance are likely to occur on the surface of the lens, and such “wrinkles” are particularly likely to occur at a position close to the anti-gate side from the center side.

  The present invention has been made in view of such knowledge, and in manufacturing a polarizing plastic lens by inserting a polarizing sheet into a mold and insert molding, a polarizing plastic lens in which the generation of wrinkles on the lens surface is suppressed. And an object of the present invention is to provide a manufacturing method thereof.

  The above-mentioned problems occur because the polarizing sheet is deformed so as to follow the molding surface while being slightly stretched along the flow direction of the injected molten resin. If it is too deep, the polarizing sheet is in the state where the center side is in contact with the molding surface when loaded in the mold, and the elongation is hindered in the process of the polarizing sheet closely contacting the molding surface from the center side toward the outer peripheral side. It is thought that it is because it ends. Then, “wrinkles” occur in the part that cannot be extended, and the force to stretch the polarizing sheet at this time also acts in the direction perpendicular to the resin filling direction, but in the direction along the filling direction. Since it is larger, it is considered that “wrinkles” are likely to occur at a position close to the opposite gate side from the center side.

As a result of intensive studies, the present inventors have found that there is a difference in bending accuracy between the direction along the polarization axis and the direction perpendicular to the polarization axis when bending the polarizing sheet. It came to obtain the knowledge that.
That is, in order to bend the polarizing sheet, as disclosed in Patent Document 1, a mold having a desired curved surface is prepared, and the polarizing sheet is pressed and bent while applying heat to the mold. However, in this case, the direction along the polarization axis tends to be bent to the desired curve, whereas in the direction orthogonal to the polarization axis, the curve on the center side is shallow and the curve on the outer periphery side is deeper. It turns out that there is a tendency to turn.

  In general, a spectacle lens is formed in a circular shape so as to be compatible with spectacle frames having various shapes, and is appropriately cut out in accordance with the shape of the spectacle frame to be incorporated. For this reason, in many cases, the portion that protrudes from the top and bottom of the spectacle frame is cut off. Therefore, when molding a plastic lens for spectacles by an injection molding method, it is above or below when cutting out according to the shape of the spectacle frame. The mold is designed so that the gate is arranged at the position. Then, since the polarizing lens is incorporated into the spectacle frame so that the polarization axis is horizontal, in order to insert the polarizing plastic lens into the mold designed in this way and insert-mold the polarizing plastic lens, The mold is loaded so that the polarization axis is perpendicular to the filling direction of the resin. As a result, the bending accuracy is low, the curve on the center side is shallow, and the direction perpendicular to the polarization axis that tends to bend to the deep curve on the outer periphery side coincides with the resin filling direction. The present inventors have found that this is the cause of the occurrence, and have completed the present invention.

  That is, the manufacturing method of the polarizing plastic lens according to the present invention includes the resin filling direction in the manufacturing of the polarizing plastic lens by insert molding so that the lens main body is molded integrally with the polarizing sheet loaded in the mold. The polarizing sheet is loaded into the mold so that the polarizing axes of the polarizing sheet and the polarizing sheet are not orthogonal to each other.

  A polarizing plastic lens according to the present invention is a polarizing plastic lens that is insert-molded so that a lens body is molded integrally with a polarizing sheet loaded in a mold, and passes through the center of the lens to the center of a gate mark. The direction of travel and the polarization axis of the polarizing sheet are not orthogonal to each other.

  According to the present invention, when a polarizing plastic lens is manufactured by inserting a polarizing sheet into a mold and insert molding, it is possible to manufacture a polarizing plastic lens in which generation of wrinkles on the lens surface is suppressed.

It is explanatory drawing which shows an example of an injection molding apparatus. It is sectional drawing which shows the outline of the shaping | molding die with which the injection molding apparatus shown in FIG. It is AA sectional drawing of FIG. It is BB sectional drawing of FIG. It is explanatory drawing which shows an example which loads a polarizing sheet on the stationary mold side of a shaping | molding die. It is a flowchart which shows each step in the manufacturing method of the polarizing plastic lens which concerns on embodiment of this invention. FIG. 2 is an explanatory view showing a state in which a polarized plastic lens molded using the injection molding apparatus of FIG. 1 is taken out from a mold.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[Injection molding equipment]
FIG. 1 is an explanatory view showing an example of an injection molding apparatus, and the method for manufacturing a polarizing plastic lens according to this embodiment can be implemented by suitably using such an injection molding apparatus.

The injection molding apparatus shown in FIG. 1 includes a mold 50 having a movable mold 1 and a fixed mold 2 as a pair of split molds divided by a parting line PL, and opening / closing and mold of the mold 50 by a toggle link mechanism 65. A mold clamping device 60 that performs clamping and an injection device 80 that melts, kneads, and measures the raw material resin charged from the hopper 81 and injects it from the nozzle 85 are provided.
2 is a cross-sectional view showing an outline of a mold 50 provided in the injection molding apparatus shown in FIG.

[Injection device]
An injection apparatus 80 provided in the injection molding apparatus shown in FIG. 1 has a heating cylinder 82 having a nozzle 85 formed at the tip. Inside the heating cylinder 82, a screw whose rotation and forward / backward movement are controlled by the drive unit 84 is disposed.

  Further, a hopper 81 for feeding pellet-shaped raw material resin into the heating cylinder 82 is connected to the proximal end side of the heating cylinder 82. The raw material resin charged into the heating cylinder 82 from the hopper 81 is melted and kneaded by shearing heat and heating from the heater provided in the heating cylinder 82 while being sheared and pulverized by a screw rotating in the heating cylinder 82. Is sent to a cylinder front chamber formed between the front end of the nozzle and the nozzle 85 and weighed. Thereafter, a predetermined amount of raw material resin that is adjusted to a viscosity suitable for injection molding and in a molten state is injected from the nozzle 85. .

[Clamping device]
In the injection molding apparatus shown in FIG. 1, the mold clamping device 60 is constructed by laying a plurality of tie bars 63 between a fixed die plate 61 and a rear plate 62 erected on a gantry 66 at a predetermined interval, and a movable die plate 64. However, the tie bar 63 is guided so as to be movable. A molding die 50 is attached between the fixed die plate 61 and the movable die plate 64, and a toggle link mechanism 65 is attached between the rear plate 62 and the movable die plate 64.
As a result, when the toggle link mechanism 65 is driven, the movable die plate 64 is guided by the tie bar 63 to advance and retreat, and accordingly, the mold 50 is opened and closed and the mold is clamped.

  Here, the toggle link mechanism 65 is configured so that the screwed crosshead 73 moves along the ball screw 72 as the ball screw 72 connected to a motor (not shown) rotates. When the cross head 73 moves to the movable die plate 64 side, the toggle link 71 extends linearly by the connecting link 74, and the movable die plate 64 moves (advances) so as to approach the fixed die plate 61. On the contrary, when the cross head 73 moves to the rear plate 62 side, the toggle link 71 is bent inward by the connecting link 74, and the movable die plate 64 moves away from the fixed die plate 61 (retracts). To do.

[Molding mold]
FIG. 2 is a cross-sectional view schematically showing the mold 50 used in the present embodiment, and corresponds to a cross-sectional view showing a cross section of the mold 50 shown in FIG. 1 cut along a plane perpendicular to the paper surface passing through the central axis. And the initial state of mold closing is shown. 3 is a cross-sectional view taken along the line AA in FIG. 2, and FIG. 4 is a cross-sectional view taken along the line BB in FIG.

  In the examples shown in these drawings, the mold main body 4 of the movable mold 1 is fixed to the movable die plate 64 via the mold mounting member 16, and the mold main body 8 of the fixed mold 2 is fixed via the mold mounting member 15. It is fixed to a fixed die plate 61. As a result, the mold 50 is attached between the fixed die plate 61 and the movable die plate 64 of the mold clamping device 60.

The mold body 4 of the movable mold 1 has two insert guide members 5 and mold plates 6 and 7 for holding them. Inside the insert guide member 5, an insert 11 having a molding surface corresponding to one surface of the plastic lens to be molded (in the example shown, the concave surface) is formed with respect to the parting line PL. It is stored so that it can slide in a right angle direction.
The mold body 8 of the fixed mold 2 includes two insert guide members 9 and a template 10, and the insert guide member 9 is held by the template 10 and the mold attachment member 15. Inside the insert guide member 9, an insert 12 having a molding surface corresponding to the other surface of the plastic lens to be molded (in the example shown, the surface on the convex surface side) is formed with respect to the parting line PL. It is stored so that it can slide in a right angle direction.

A molding die 50 having such a movable die 1 and a fixed die 2 is formed between the movable die 1 and the fixed die 2 in each of the insert 11 on the movable die 1 side and the insert 12 on the fixed die 2 side. A cavity 3 including a molding surface is formed.
Between the movable mold 1 and the fixed mold 2, a runner 49 as a resin flow path connected to each cavity 3 through a gate G, together with two cavities 3 for molding a plastic lens of a predetermined shape. Is to be formed. A sprue bush 47 that forms a sprue 48 connected to the runner 49 at a right angle is attached to the template 10 of the fixed mold 2.

  The die mounting member 16 on the movable die 1 side is provided with a hydraulic cylinder 19 corresponding to each of the inserts 11, and a piston rod 21 connected to the piston 20 is fixed to one end side of the hydraulic cylinder 19. The back insert 22 is penetrated. And the T-shaped clamp member 23 provided at the front-end | tip of each piston rod 21 is engaged / disengaged in the T-shaped groove 24 formed in the back surface (surface on the opposite side to the surface in which the molding surface was formed) of the insert 11. It is freely engaged.

  Thus, with the mold 50 opened, the piston rods 21 of the respective hydraulic cylinders 19 are advanced, and the T-shaped clamp members 23 provided at the tips of the piston rods 21 are protruded from the insert guide members 5. Thus, the insert 11 can be exchanged according to the plastic lens to be molded. When the piston rod 21 of each hydraulic cylinder 19 is retracted, the insert 11 attached to the T-shaped clamp member 23 is housed inside the insert guide member 5.

  Similarly, a hydraulic cylinder 26 is provided in the mold mounting member 15 on the fixed mold 2 side so as to correspond to each of the inserts 12, and a piston rod 28 connected to the piston 27 penetrates the mold mounting member 15. doing. A T-shaped clamp member 29 provided at the tip of each piston rod 28 is engaged with or disengaged from a T-shaped groove 30 formed on the back surface of the insert 12 (the surface opposite to the surface on which the molding surface is formed). It is freely engaged.

  Thus, with the mold 50 opened, the piston rod 28 of each hydraulic cylinder 26 is advanced, and the T-shaped clamp member 29 provided at the tip of each piston rod 28 is projected from the insert guide member 9. Thus, the insert 12 can be exchanged according to the plastic lens to be molded. When the piston rod 28 of each hydraulic cylinder 26 is retracted, the insert 12 attached to the T-shaped clamp member 29 is accommodated in the insert guide member 9.

  When the mold body 4 of the movable mold 1 is fixed to the movable die plate 64, the mold body 4 is bolted to the mold mounting member 16 composed of the first member 16A and the second member 16B, as shown in FIG. 17 is attached. At this time, a plurality of disc springs 17 </ b> A inserted on the outer periphery of the bolt 17 are interposed between the mold body 4 of the movable mold 1 and the mold mounting member 16, and the mold body 4 and the mold of the movable mold 1 are interposed. A gap S is formed between the mounting member 16 and the mounting member 16.

The gap S is generated when the movable die plate 64 further advances after the molding die 50 is closed, and the die mounting member 16 guided by the guide pins 18 is pressed against the elastic force of the disc spring 17A. It is designed to be closed. Accordingly, in the illustrated example, each hydraulic cylinder 19 provided on the mold attachment member 16 presses the insert 11 via the back insert 22. Thereby, the volume of the cavity 3 when mold clamping is made variable, and the molten resin injected and filled in the cavity 3 can be compressed by the insert 11.
The guide pin 18 protrudes toward the fixed mold 2 so as to guide the opening / closing operation of the mold 50 and is inserted through an insertion hole formed in the fixed mold 2.

A pressure receiving member 32 is attached to the other end side of the hydraulic cylinder 19 provided on the die attaching member 16 on the movable die 1 side. When the eject rod 34 inserted from the hole 33 formed in the mold attachment member 16 presses the pressure receiving member 32, the hydraulic cylinder 19, the back insert 22 and the insert 11 are also pressed, and the lens molded in the cavity 3 is Extruded.
At the same time, an eject pin 35 is disposed at the center of the mold attachment member 16 so as to be movable back and forth in parallel with the opening / closing direction of the mold 50. When the pressure receiving member 36 attached to the eject pin 35 is pressed by the eject rod 38 inserted from the hole 37 formed in the mold attaching member 16, the eject pin 35 is pushed out.
Therefore, when the mold is opened, the ejected rods 34 and 38 are advanced to take out the molded product.

  As shown in FIG. 4, the spring force of the spring 42 wound around the outer periphery of the eject return pin 41 acts on the pressure receiving member 36 in the left direction in the figure. Although not particularly shown, the pressure receiving member 32 has the same structure so that a leftward spring force acts in the drawing. Thus, when the eject rods 34 and 38 are retracted, the pressure receiving members 32 and 36 are also retracted and returned to the standby position.

  Moreover, the shaping | molding die 50 has the nozzle shut mechanism 90 which obstruct | occludes the nozzle 85 of the injection apparatus 80, as shown in FIG. The nozzle shut mechanism 90 has a nozzle shut pin 91 as a blocking member protruding into the sprue 48 formed by the sprue bush 47. The nozzle shut pin 91 is connected to a piston rod 94 of a hydraulic cylinder 93 via a connecting piece 92, and the hydraulic cylinder 93 is fixed to the mold mounting member 15 by a cylinder mounting plate 95. As a result, when the hydraulic cylinder 93 is driven in a state where the nozzle 85 is in pressure contact with the sprue bush 47, the nozzle shut pin 91 projects into the sprue 48 and closes the nozzle 85, thereby preventing back flow of the resin. Yes.

[Polarized plastic lens manufacturing method]
In the present embodiment, a polarizing plastic lens is manufactured by insert molding so that the lens body is molded integrally with the polarizing sheet S loaded in the molding die 50 using the injection molding apparatus as described above. To do.

  The polarizing plastic lens is usually manufactured so that the polarizing sheet S is integrated with the lens surface. For this reason, in the present embodiment, a polarizing sheet S that is cut out in accordance with the outer shape of the molding surface formed in the insert 12 on the fixed mold 2 side and bent according to the molding surface is prepared. The polarizing sheet S is loaded on the fixed mold 2 side of the mold 50, but is not limited thereto.

In bending the polarizing sheet S, there is a difference in bending accuracy between the direction along the polarization axis A and the direction perpendicular to the polarization axis A, and the direction along the polarization axis A is almost aimed. In contrast to the tendency to bend into a street curve, in the direction perpendicular to the polarization axis A, the center-side curve tends to be shallow and the outer circumference side tends to bend to a deeper curve as described above.
In the present embodiment, in consideration of such bending characteristics of the polarizing sheet S, the polarizing sheet S is loaded into the mold 50 so that the resin filling direction and the polarizing axis A of the polarizing sheet S are not orthogonal. For example, the inclination of the polarization axis A with respect to the resin filling direction is preferably 45 ° or less, more preferably 30 ° or less, further preferably 20 ° or less, particularly preferably 10 ° or less, and most preferably 5 ° or less. The polarizing sheet S is loaded into the mold 50. By doing in this way, the resin is filled along the direction along the polarization axis A with high bending accuracy, and it is good that “wrinkles” that are poor appearance appear on the surface of the manufactured lens. Therefore, a high-quality polarized plastic lens can be manufactured.

Here, the filling direction of the resin means a direction in which the injected molten resin is filled into the cavity 3 through the gate G. More specifically, the center line of the runner 49 in the immediate vicinity of the gate G is defined as the gate. The direction extending from the G side to the opposite gate side is referred to, and this direction is indicated by a one-dot chain line in FIG.
FIG. 5 is a schematic view of the main part of the parting surface of the fixed mold 2 viewed from the movable mold 1 side, and shows an example in which the polarizing sheet S is loaded on the fixed mold 2 side. The axis A is schematically indicated by a thick line.

  In order to position the polarizing sheet S when the polarizing sheet S is loaded in the molding die 50 in this way, for example, a positioning tab is formed on the periphery of the polarizing sheet S and engaged therewith. The polarizing sheet S can be positioned as previously proposed in Japanese Patent Application No. 2014-067673 by forming a notch to be formed on the mold 50 side.

Moreover, the polarizing plastic lens manufactured in the present embodiment is not particularly limited, and may be a lens with a degree or a lens without a degree. The lens shape may be either spherical or aspherical, and may be any of a single focal lens, a progressive power lens, and a multifocal lens. However, for example, in the case of manufacturing a lens having directionality in the optical surface shape such as a progressive power lens or a multifocal lens, the manufactured polarizing plastic lens is a pair of spectacles so that the polarization axis A is horizontal. It is necessary to consider being incorporated into the frame. In such a case, the molding surfaces formed on each of the insert 11 on the movable mold 1 side and the insert 12 on the fixed mold 2 side of the mold 50 are stored in the mold 50 and fixed. The lens is formed so that the direction of the optical surface shape of the lens to be molded is a direction suitable for the direction of the polarization axis A of the polarizing sheet S loaded in the mold 50.
As the polarizing plastic lens manufactured in the present embodiment, a single focus lens is preferable because it is more effective in suppressing wrinkles.

Further, in this embodiment, the curve in the direction along the polarization axis A with high bending accuracy matches the curve of the molding surface along the direction corresponding to this (however, the case where the curve generally matches within the error range). By using the polarizing sheet S that has been subjected to bending so as to include (including), it is possible to better suppress the occurrence of “wrinkles” that are defective in appearance on the surface of the manufactured lens, but it is not limited thereto. .
If the curve of the polarizing sheet is deeper than the molding surface, the polarizing sheet is in contact with the molding surface when loaded in the mold, and the polarizing sheet is in close contact with the molding surface from the center side toward the outer periphery. As described above, it is considered that the wrinkle is generated in the portion where the elongation is hindered in the course of the process and the elongation cannot be achieved. On the other hand, when the curve of the polarizing sheet is a shallow curve larger than the curvature of the molding surface, the polarizing sheet is in a state where the center side floats from the molding surface when loaded in the mold, and the polarizing sheet It is considered that can be deformed so as to follow the molding surface without hindering the elongation. Therefore, the polarizing sheet is bent so that the curve in the direction along the polarization axis A is shallower than the curve of the forming surface along the corresponding direction to such an extent that the polarizing sheet can be deformed to follow the forming surface. Even when the processed polarizing sheet S is used, it is possible to suppress the occurrence of “wrinkles”. When manufacturing a polarizing plastic lens having a similar optical surface shape, such a polarizing sheet S can be used. It may be used in common.

  More specifically, the method for manufacturing a polarizing plastic lens according to the present embodiment can be performed by sequentially performing the steps (ST1 to ST10) shown in the flowchart of FIG.

  In ST1, a resin pressurizing condition is set. This is because, in order to apply an appropriate pressure to the resin in the cavity 3 in advance, the mold clamping force is adjusted according to the characteristics (lens shape, lens power, etc.) of the polarized plastic lens to be molded. Is.

In ST2, weighing is performed. In the injection device 80, the pellet-shaped raw resin charged from the hopper 81 is melted and kneaded by shearing heat and heating from the heater provided in the heating cylinder 82 while being sheared and pulverized by a screw rotating in the heating cylinder 82. While being sent, it is sent to the cylinder front chamber formed between the tip of the screw and the nozzle 85 and weighed. Here, an amount of molten resin necessary for filling the cavity 3, the runner 49, and the sprue 48 is measured.
As the raw material resin, a thermoplastic resin such as a polycarbonate resin or an acrylic resin generally used for molding this type of plastic lens can be used.

  In ST3, the mold 50 loaded with the polarizing sheet S as described above is closed at the parting line PL. Specifically, when the toggle link mechanism 65 is driven to advance the cross head 73, the toggle links 71A and 71B extend, and the movable die plate 64 advances toward the fixed die plate 61. 50 molds are closed. At this time, a gap S is maintained in a state where the disc spring 17A interposed between the mold body 4 of the movable mold 1 and the mold mounting member 16 is not compressed, and the fixed mold 2 and the movable mold 1 are separated by the parting line PL. Close the mold. In this state, the gap S is set to the maximum opening amount.

  In ST4, the cavity volume is set. In ST3, the crosshead 73 is further advanced to a preset position (cavity volume setting position) from the state in which the movable mold 1 and the fixed mold 2 are brought into close contact with each other by the parting line PL. As a result, the toggle links 71A and 71B are extended, and the movable die plate 64 is moved toward the fixed die plate 61 and moved to the cavity expansion position. The cavity enlargement amount is determined by setting the crosshead position. As a result, the gap S of the mold 50 is reduced leaving the cavity enlargement. At this time, the volume (thickness) of the cavity 3 is larger than the lens volume (thickness) to be molded, that is, the thickness of the extracted molded product. Further, since the disc spring 17A is compressed, some clamping force is generated as the reaction force.

  In ST5, injection is performed. The molten resin weighed in ST2 is injected into the mold 50 through the passage of the injection nozzle 85. That is, the molten resin introduced into the heating cylinder 82 of the injection device 80 and weighed is injected. Then, molten resin is injected from a nozzle 85 formed at the tip of the heating cylinder 82 and filled into the cavity 3 through the sprue 48, the runner 49, and the gate G. When the molten resin is filled into the cavity 3, the injection speed is controlled to be constant.

  In ST6, the resin is sealed in the mold. After injecting a predetermined amount of resin at T5, the cross head 73 is further advanced immediately before the injection filling of the molten resin is completed. Then, after the injection filling is completed, the nozzle shut pin 91 is protruded into the sprue 48 by the nozzle shut mechanism 90 and the nozzle 85 is closed. Thereby, the filled molten resin is enclosed in the mold 50 in a compressed and pressurized state.

  In ST7, resin pressurization is performed. In ST6, the crosshead 73 starts to advance, and when the crosshead 73 advances to the origin (zero position) and stops, the toggle links 71A and 71B extend, so that the molten resin contained in the mold 51 is compressed. Pressed.

  In ST8, cooling is performed. For this purpose, the temperature of each part (insert, insert guide member, etc.) of the mold 50 is adjusted by the mold temperature adjusting device 51 so that the temperature is set to the Tg point or less according to the lens characteristics to be molded. Perform fluid temperature control. When the molten resin contained in the mold 50 is cooled while being compressed and pressurized, the raw material resin injected and filled in the cavity 3 is solidified as the cooling progresses in the compressed state. By contracting, a plastic lens having a predetermined volume is molded.

  In ST9, a release operation is performed. In the mold release operation, the crosshead 73 of the toggle link mechanism 65 is moved backward toward the rear plate 62 to open the mold 50.

  In ST10, a molded product ejecting operation is performed. When the cross head 73 is retracted to the end, the distance between the movable die plate 64 and the fixed die plate 61 is maximized, and the mold 50 is divided by the parting line PL to open the mold. At the time of opening the mold, the eject rods 34 and 38 are advanced to take out the molded polarizing plastic lens.

As shown in FIG. 7, the polarizing plastic lens thus molded includes a lens portion 102 formed by the cavity 3, a connecting portion 103 formed by the runner 49, and a rod-like portion 104 formed by the sprue 48. And are taken out from the molding die 50 in a connected state. And after taking out from the shaping | molding die 50, the lens part 102 is cut off, the post-processing required for this is performed, and after it is finished to a final product, it is offered to the market as a polarizing plastic lens.
In FIG. 7, the polarization axis A of the polarizing sheet S is schematically shown.

  The trace separated from the connecting portion 103 remaining in the lens portion 102 is generally referred to as a gate trace. Such a gate mark is usually not visually discernible by performing a polishing process or the like. However, in a lens molded by an injection molding method, the distortion around the gate mark differs from other parts. Has occurred. It is possible to specify the position of the gate trace by examining such distortion, and it is assumed that the gate trace including the part where such distortion is generated.

  The polarizing plastic lens manufactured in the present embodiment is characterized in that the direction toward the center of the gate mark through the center of the lens and the polarization axis A of the polarizing sheet S are not orthogonal. For example, a polarizing plastic lens insert-molded integrally with the polarizing sheet S is incorporated in the spectacle frame so that the polarization axis A of the polarizing sheet S is horizontal, so that the gate is formed on the left and right sides when incorporated in the spectacle frame. The inclination of the polarization axis A with respect to the direction passing through the center of the lens toward the center of the gate mark is preferably 45 ° or less, more preferably 30 ° or less, and even more preferably 20 ° or less, in particular. A polarizing plastic lens that is preferably 10 ° or less, and most preferably 5 ° or less, can be said to be a high-quality polarizing plastic lens in which the occurrence of “wrinkles” that are poor in appearance on the lens surface is suppressed.

  Although the present invention has been described with reference to the preferred embodiments, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the present invention. Nor.

  For example, in the above-described embodiment, an example in which the polarizing plastic lens is manufactured using the molding die 50 for taking two pieces is shown, but a single piece or a multiple piece of three pieces or more may be used.

  INDUSTRIAL APPLICATION This invention can be utilized as a technique which can insert-mold a polarizing plastic lens with high quality.

50 Mold G Gate S Polarizing sheet A Polarization axis

Claims (6)

In manufacturing a polarizing plastic lens by insert molding so that the lens body is molded integrally with the polarizing sheet loaded in the mold,
A method for producing a polarizing plastic lens, wherein the polarizing sheet is loaded into the mold so that a resin filling direction and a polarizing axis of the polarizing sheet are not orthogonal to each other.   The method for producing a polarizing plastic lens according to claim 1, wherein the polarizing sheet is loaded into the mold so that the polarization axis of the polarizing sheet with respect to the resin filling direction is 45 ° or less.   3. The method for producing a polarizing plastic lens according to claim 1, wherein the polarizing sheet is bent so that the curve in the direction along the polarization axis matches the curve of the molding surface along the direction corresponding thereto. .   The polarizing plastic lens according to claim 1 or 2, wherein the polarizing sheet is bent so that a curve in a direction along the polarization axis is shallower than a curve of a molding surface along a direction corresponding thereto. Method. A polarizing plastic lens that is insert-molded so that the lens body is molded integrally with a polarizing sheet loaded in a mold,
A polarizing plastic lens, characterized in that the direction passing through the center of the lens toward the center of the gate mark and the polarization axis of the polarizing sheet are not orthogonal.   The polarizing plastic lens according to claim 5, wherein an inclination of a polarization axis of the polarizing sheet with respect to a direction passing through the center of the lens toward a center of the gate mark is 45 ° or less.

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