JP6702652B2 - Polarized plastic lens and manufacturing method thereof - Google Patents

Description

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

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

Further, in manufacturing a functional lens such as a polarizing lens by an injection molding method, it is known that a functional sheet such as a polarizing sheet is loaded into a mold according to a desired function and insert molding is performed ( For example, see Patent Document 1).

JP, 2006-47586, A

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

However, it is not easy to bend the polarizing sheet to finish it into an aspherical surface that matches the lens shape while suppressing distortion of the curved surface. Therefore, in Patent Document 1, the polarizing sheet is subjected to a primary bending process to form an intermediate processed product having a curved surface with a smaller degree of bending than the final product, and the intermediate processed product is subjected to the secondary processing. Bending is applied to finish the final product with a predetermined aspherical curved surface, and gradual bending prevents the polarizing sheet from being subjected to excessive force.

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

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

The present invention has been made in view of such findings, and in manufacturing a polarizing plastic lens by inserting a polarizing sheet into a molding die and performing insert molding, the polarizing plastic lens in which the occurrence of wrinkles on the lens surface is suppressed And a method for manufacturing the same.

The above problems occur because the polarizing sheet deforms so as to follow the molding surface while being slightly stretched along the flow direction of the injected molten resin, but the curve of the polarizing sheet is more than the molding surface. If the depth is too deep, the center of the polarizing sheet is in contact with the molding surface when it is loaded into the mold, and the expansion is hindered when the polarizing sheet is in close contact with the molding surface from the center side toward the outer peripheral side. It is thought that it is because it ends up. Then, "wrinkles" occur in the part that cannot be stretched, and the force to stretch the polarizing sheet at this time also acts in the direction orthogonal to the filling direction of the resin, but in the direction along the filling direction. Since it is larger, "wrinkles" are likely to occur at a position closer to the gate side from the center side.

The inventors of the present invention have made extensive studies and found that when bending a polarizing sheet, there is a difference in bending accuracy between the direction along the polarization axis and the direction orthogonal to the polarization axis. It came to the knowledge that.
That is, in order to bend the polarizing sheet, a mold having a desired curved surface is prepared, and the polarizing sheet is pressed and bent while applying heat to the mold, as disclosed in Patent Document 1. However, at this time, in the direction along the polarization axis, there is a tendency to be able to bend to a curve that is almost the target, whereas in the direction orthogonal to the polarization axis, the curve on the center side is shallow and the curve on the outer side is deeper. It turns out that there is a tendency to turn.

Generally, the spectacle lens is formed into a circular shape so that it can be adapted to spectacle frames of various shapes, and is appropriately cut according to the shape of the spectacle frame to be incorporated. For this reason, in many cases, the parts protruding above and below the spectacle frame are cut off. The mold is designed so that the gate is placed at the position. Then, the polarizing lens will be installed in the spectacle frame so that the polarization axis will be horizontal, so to load the polarizing sheet into the mold designed in this way and insert-mold the polarizing plastic lens, The mold is loaded so that the polarization axis is orthogonal 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 curve on the outer peripheral side tends to bend to a deeper curve. The present inventors have found that it is a cause of occurrence, and have completed the present invention.

That is, the method for manufacturing a polarized plastic lens according to the present invention is a resin filling direction in manufacturing a polarized plastic lens by insert molding so that the lens body is integrally molded with the polarizing sheet loaded in the molding die. And the polarizing sheet is loaded into the mold so that the polarization axes of the polarizing sheet are not orthogonal to each other.

The polarizing plastic lens according to the present invention is a polarizing plastic lens that is insert-molded so that the lens body is molded integrally with the polarizing sheet loaded in the molding die. The polarization direction of the polarizing sheet is not orthogonal to the facing direction.

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

It is an explanatory view showing an example of an injection molding device. It is sectional drawing which shows the outline of the shaping|molding die with which the injection molding apparatus shown in FIG. 1 is equipped. FIG. 3 is a sectional view taken along line AA of FIG. It is a BB sectional view of FIG. It is explanatory drawing which shows an example which loads a polarizing sheet on the fixed mold side of a shaping|molding die. It is a flowchart which shows each step in the manufacturing method of the polarized plastic lens which concerns on embodiment of this invention. FIG. 2 is an explanatory view showing a state where a polarized plastic lens molded by using the injection molding device of FIG. 1 is taken out from a molding die.

Embodiments of the present invention will be described below 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 polarized plastic lens according to the present embodiment can be implemented by suitably utilizing 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 a toggle link mechanism 65 to open and close the mold 50 and molds. It is provided with a mold clamping device 60 for clamping, and an injection device 80 for injecting a raw material resin fed from a hopper 81 from a nozzle 85 after melting, kneading, and weighing with a heating cylinder 82.
2 is a cross-sectional view showing the outline of the molding die 50 included in the injection molding apparatus shown in FIG.

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

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

[Clamping device]
In the injection molding apparatus shown in FIG. 1, the mold clamping device 60 has a plurality of tie bars 63 installed between a fixed die plate 61 and a rear plate 62, which are erected on a stand 66 at predetermined intervals, and a movable die plate 64. However, it is configured so that it can be moved by being guided by the tie bar 63. The forming die 50 is attached between the fixed die plate 61 and the movable die plate 64, and the 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 bars 63 and moves back and forth, and accordingly, the molding die 50 is opened and closed and the die is clamped.

Here, in the toggle link mechanism 65, the cross head 73 screwed together moves along with 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 (forwards) 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 bends inward by the connecting link 74, and the movable die plate 64 moves (retracts) away from the fixed die plate 61. To do.

[Molding die]
FIG. 2 is a cross-sectional view showing an outline of the molding die 50 used in the present embodiment, and corresponds to a cross-sectional view showing a cross-section of the molding die 50 shown in FIG. And shows the initial state when the mold is closed. 3 is a sectional view taken along the line AA of FIG. 2, and FIG. 4 is a sectional view taken along the line BB of FIG.

In the examples shown in these figures, the mold body 4 of the movable mold 1 is fixed to the movable die plate 64 via the mold attachment member 16, and the mold body 8 of the fixed mold 2 is interposed via the mold attachment member 15. It is fixed to the fixed die plate 61. As a result, the molding die 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 (a concave surface in the illustrated example) of the plastic lens to be molded is formed with respect to the parting line PL. It is stored so that it can slide in the right angle direction.
The mold body 8 of the fixed mold 2 has two insert guide members 9 and a mold plate 10, and the insert guide member 9 is held by the mold plate 10 and the mold mounting member 15. Inside the insert guide member 9, an insert 12 having a molding surface corresponding to the other surface (the convex surface in the illustrated example) of the plastic lens to be molded is formed with respect to the parting line PL. It is stored so that it can slide in the 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.
In addition, between the movable mold 1 and the fixed mold 2, two cavities 3 for molding a plastic lens having a predetermined shape and a runner 49 as a resin flow path connected to each cavity 3 via a gate G are provided. Are formed. A sprue bush 47 forming a sprue 48 connected to the runner 49 at a right angle is attached to the template 10 of the fixed mold 2.

A hydraulic cylinder 19 is provided on the mold mounting member 16 on the movable mold 1 side so as to correspond to each of the inserts 11, and a piston rod 21 connected to a piston 20 is fixed to one end side of the hydraulic cylinder 19. It penetrates through the inside of the formed back insert 22. The T-shaped clamp member 23 provided at the tip of each piston rod 21 is engaged with and disengaged from the T-shaped groove 24 formed on the back surface of the insert 11 (the surface opposite to the surface on which the molding surface is formed). It is freely engaged.

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

Similarly, the die mounting member 15 on the fixed die 2 side is also provided with a hydraulic cylinder 26 corresponding to each of the inserts 12, and a piston rod 28 connected to a piston 27 penetrates through the die mounting member 15. is doing. The T-shaped clamp member 29 provided at the tip of each piston rod 28 is engaged with and disengaged from the 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.

As a result, with the molding die 50 opened, the piston rods 28 of the respective hydraulic cylinders 26 are advanced so that the T-shaped clamp members 29 provided at the tips of the respective piston rods 28 project from the insert guide member 9. Thus, the insert 12 can be replaced according to the plastic lens to be molded. When the piston rod 28 of each hydraulic cylinder 26 retracts, the insert 12 attached to the T-shaped clamp member 29 is housed inside the insert guide member 9.

Further, when fixing the die body 4 of the movable die 1 to the movable die plate 64, the die body 4 is bolted to the die mounting member 16 including the first member 16A and the second member 16B as shown in FIG. It is attached at 17. At this time, a plurality of disc springs 17A inserted into 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 of the movable mold 1 and the mold body 4 are separated from each other. A gap S is formed between the mounting member 16 and the mounting member 16.

The gap S is formed by moving the movable die plate 64 further after the molding die 50 is closed and pressing the die mounting member 16 guided by the guide pin 18 against the elastic force of the disc spring 17A. It is designed to be closed. Along with this, in the illustrated example, the hydraulic cylinders 19 provided on the mold mounting member 16 press the insert 11 via the back insert 22. Thereby, the volume of the cavity 3 when the mold is clamped is made variable, and the molten resin injected and filled in the cavity 3 can be pressurized and compressed by the insert 11.
The guide pin 18 projects toward the fixed mold 2 and is inserted into an insertion hole formed in the fixed mold 2 so as to guide the opening/closing operation of the molding die 50.

A pressure receiving member 32 is attached to the other end side of the hydraulic cylinder 19 provided in 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 mounting 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 It is supposed to be pushed out.
At the same time, an ejector pin 35 is arranged at the center of the die mounting member 16 so as to be movable back and forth in parallel with the opening/closing direction of the molding die 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 moved forward to take out the molded product.

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

Further, as shown in FIG. 4, the molding die 50 has a nozzle shut mechanism 90 that closes the nozzle 85 of the injection device 80. The nozzle shut mechanism 90 has a nozzle shut pin 91 as a blocking member that projects 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 die 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 to close the nozzle 85 and prevent reverse flow of resin. There is.

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

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

When the polarizing sheet S is bent, there is a difference in the bending accuracy between the direction along the polarization axis A and the direction orthogonal to the polarization axis A, and in the direction along the polarization axis A, it is almost aimed. As described above, there is a tendency that the curve can be bent into a straight curve, while the curve on the center side is shallow and the curve on the outer peripheral side is bent in the direction orthogonal to the polarization axis A.
In the present embodiment, in consideration of such bending properties of the polarizing sheet S, the polarizing sheet S is loaded into the molding die 50 so that the filling direction of the resin and the polarization axis A of the polarizing sheet S are not orthogonal to each other. For example, the inclination of the polarization axis A with respect to the filling direction of the resin is preferably 45° or less, more preferably 30° or less, even more preferably 20° or less, particularly preferably 10° or less, and most preferably 5° or less. Then, the polarizing sheet S is loaded into the molding die 50. By doing so, the resin is filled along the direction along the polarization axis A, which is highly accurate in bending, and it is preferable that the appearance of "wrinkles", which is a poor appearance, occurs on the manufactured lens surface. Therefore, a high-quality polarized plastic lens can be manufactured.

Here, the resin filling direction is a direction in which the injected molten resin is filled into the cavity 3 through the gate G, and more specifically, the center line of the runner 49 in the immediate vicinity of the gate G is the gate. The direction extending from the G side to the anti-gate side is referred to, and this direction is shown by a dashed line in FIG.
Note that FIG. 5 is a schematic view of a main part of the stationary die 2 from the movable die 1 side, showing an example in which the polarizing sheet S is loaded on the stationary die 2 side. The axis A is schematically shown by a thick line.

In order to position the polarizing sheet S when the polarizing sheet S is loaded into the molding die 50 in this way, although not shown in the drawing, for example, a positioning tab is formed on the periphery of the polarizing sheet S and is engaged with the positioning tab. The polarizing sheet S can be positioned as previously proposed by the applicant in Japanese Patent Application No. 2014-067743 by forming a notch on the side of the molding die 50.

The polarizing plastic lens manufactured in this embodiment is not particularly limited, and may be a lens with a degree or a lens without a degree. The lens shape may be spherical or aspherical, and may be a single-focus lens, a progressive-power lens, or a multifocal lens. However, for example, in the case of manufacturing a lens having a directional optical surface shape such as a progressive addition lens or a multifocal lens, the manufactured polarizing plastic lens is a pair of glasses such that the polarization axis A is horizontal. It needs to be considered to be incorporated into the frame. In such a case, the molding surface 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 molding die 50, when these are housed in the molding die 50 and fixed, The lens is formed so that the direction of the optical surface shape of the lens is a direction suitable for the direction of the polarization axis A of the polarizing sheet S loaded in the molding die 50.
As the polarized plastic lens manufactured in the present embodiment, a single focus lens is preferable because it is more excellent in the effect of suppressing wrinkles.

Further, in the present embodiment, the curve in the direction along the polarization axis A with high accuracy of bending matches the curve of the molding surface along the corresponding direction (however, in the case where the curves substantially match within the error range). By using the polarizing sheet S that has been subjected to the bending process so as to include, it is possible to better suppress the occurrence of "wrinkles" that are appearance defects on the manufactured lens surface, but the present invention is not limited to this. .
If the curve of the polarizing sheet is deeper than the molding surface, the center of the polarizing sheet is in contact with the molding surface when it is loaded in the mold, and the polarizing sheet sticks to the molding surface from the center side to the outer peripheral side. As described above, it is considered that the growth is hindered in the course of the process and "wrinkles" are generated in the part where the growth cannot be completed. On the other hand, when the curve of the polarizing sheet is a shallower curve than the curvature of the molding surface, the center of the polarizing sheet is floating from the molding surface when loaded in the molding die. It is considered that the can be deformed so as to follow the molding surface without hindering the elongation. Therefore, the bending in the direction along the polarization axis A is shallower than the curve of the forming surface along the direction corresponding to this so that the polarizing sheet can be deformed to follow the forming surface. Even if the processed polarizing sheet S is used, it is possible to suppress the generation of “wrinkles”, and when the polarizing sheet S is manufactured, a polarizing plastic lens having a similar optical surface shape is manufactured. You may use it in common.

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

In ST1, resin pressurization conditions are set. This is for adjusting the mold clamping force according to the characteristics (lens shape and lens diopter, etc.) of the polarizing plastic lens to be molded in order to apply an appropriate pressure to the resin in the cavity 3 in advance. It is a thing.

In ST2, measurement is performed. In the injection device 80, the raw material resin in the form of pellets charged from the hopper 81 is sheared and crushed by the screw rotating in the heating cylinder 82, and is melted and kneaded by the shear heat and the heating from the heater provided in the heating cylinder 82. While being conveyed, it is sent to the cylinder front chamber formed between the tip of the screw and the nozzle 85 to be measured. Here, the amount of molten resin required to fill the cavity 3, the runner 49, and the sprue 48 is measured.
As the raw material resin, it is possible to use a thermoplastic resin such as a polycarbonate resin or an acrylic resin which is generally used for molding this type of plastic lens.

In ST3, the molding die 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 move the crosshead 73 forward, the toggle links 71A and 71B extend and the movable die plate 64 advances toward the fixed die plate 61, thereby forming a mold. 50 mold closing is performed. At this time, the disc spring 17A interposed between the die body 4 of the movable die 1 and the die mounting member 16 is kept in a state in which the disc spring 17A is not compressed, and the fixed die 2 and the movable die 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 movable die 1 and the fixed die 2 are brought into close contact with each other at the parting line PL, and then the crosshead 73 is further advanced to a preset position (cavity volume setting position). As a result, the toggle links 71A and 71B are extended, the movable die plate 64 is moved toward the fixed die plate 61, and is moved to the cavity expansion position. The amount of cavity expansion is determined by setting the crosshead position. As a result, the gap S of the molding die 50 is reduced, leaving a cavity expansion. At this time, the volume (wall thickness) of the cavity 3 is larger than the lens volume (wall thickness) to be molded, that is, the wall thickness of the ejection molded product. Further, since the disc spring 17A is compressed, some mold clamping force is generated as its reaction force.

In ST5, injection is performed. The molten resin measured in ST2 is injected into the molding die 50 through the passage of the injection nozzle 85. That is, the molten resin which is introduced into the heating cylinder 82 of the injection device 80 and measured is injected. Then, the molten resin is injected from the nozzle 85 formed at the tip of the heating cylinder 82, and is filled into the cavity 3 through the sprue 48, the runner 49, and the gate G. When the cavity 3 is filled with the molten resin, the injection speed is constantly controlled.

In ST6, the resin is sealed in the mold. After injecting a predetermined amount of resin at T5, the crosshead 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 mechanism 90 immediately causes the nozzle shut pin 91 to project into the sprue 48 to close the nozzle 85. As a result, the filled molten resin is enclosed in the mold 50 while being compressed and pressurized.

In ST7, resin pressure is applied. When the crosshead 73 starts to move forward in ST6 and the crosshead 73 moves forward to the origin (zero position) and stops, the toggle links 71A and 71B are fully extended, so that the molten resin enclosed in the molding die 51 is compressed. Is pressed.

In ST8, cooling is performed. To this end, the mold temperature controller 51 controls the temperature of each part (insert, insert guide member, etc.) of the mold 50 so that the temperature is set to a temperature below the Tg point according to the characteristics of the lens to be molded. Performs fluid temperature control. When the molten resin contained in the molding die 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 while being compressed and compressed, As it shrinks, a plastic lens of a predetermined volume is molded.

In ST9, the releasing operation is performed. In the mold releasing operation, the cross head 73 of the toggle link mechanism 65 is retracted toward the rear plate 62 to open the molding die 50.

In ST10, a molded product eject 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 becomes maximum, and the molding die 50 is divided from the parting line PL to open the die. At the time of this mold opening, the eject rods 34 and 38 are advanced to take out the molded polarizing plastic lens.

As shown in FIG. 7, the polarized plastic lens molded in this manner has a lens portion 102 molded by the cavity 3, a connecting portion 103 molded by the runner 49, and a rod-shaped portion 104 molded by the sprue 48. It is taken out from the molding die 50 in a state where the and are connected. Then, after being taken out from the molding die 50, the lens portion 102 is cut off, and necessary post-treatment is applied to this to make a final product, which is then put on the market as a polarized plastic lens.
In addition, in FIG. 7, the polarization axis A of the polarizing sheet S is schematically shown.

The trace separated from the connecting portion 103 remaining on the lens portion 102 is generally called a gate trace. Such a gate mark is usually made invisible to the eye by, for example, performing a polishing process. However, a lens molded by an injection molding method has a distortion around the gate mark that is different from other parts. Is occurring. The position of the gate trace can be specified by examining such strain, and the region including such strain is called the gate trace.

The polarized plastic lens manufactured in the present embodiment is characterized in that the polarization axis A of the polarizing sheet S is not orthogonal to the direction passing through the center of the lens toward the center of the gate mark. For example, since a polarizing plastic lens that is 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, the gate is installed in the left-right direction when incorporating the spectacle frame. The mark is located, and 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, further preferably 20° or less, and particularly It can be said that the polarized plastic lens of which the angle is preferably 10° or less, most preferably 5° or less is a high-quality polarized plastic lens in which the generation of “wrinkles” which is a poor appearance on the lens surface is suppressed.

Although the present invention has been described above with reference to the preferred embodiments, it is needless to say that 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 by using the molding die 50 for two-piece pickup is shown, but one piece or three or more pieces may be formed.

INDUSTRIAL APPLICABILITY The present invention can be used as a technique capable of insert molding a polarized plastic lens with high quality.

50 Mold G Gate S Polarizing Sheet A Polarizing Axis

Claims (3)

In manufacturing a polarized plastic lens by insert molding so that the lens body is molded integrally with the polarizing sheet loaded in the molding die,
So that the filling direction of the resin and the polarization axis of the polarizing sheet are not orthogonal,
The polarizing sheet is loaded into the mold so that the inclination of the polarization axis of the polarizing sheet with respect to the resin filling direction is 45° or less.
A method for manufacturing a polarized plastic lens, which is characterized by the above. Using a polarizing sheet that has been bent so that the curve along the polarization axis matches the curve of the molding surface along the corresponding direction,
The method for manufacturing the polarized plastic lens according to claim 1 . Use a polarizing sheet that is bent so that the curve along the polarization axis is shallower than the curve of the molding surface along the corresponding direction.
The method for manufacturing the polarized plastic lens according to claim 1 .

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