JPH0794154B2 - Method for manufacturing polarized polycarbonate lens - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a method for producing a polarized polycarbonate lens having little optical distortion and excellent impact resistance,
The polarizing lens produced by the manufacturing method of the present invention has little optical distortion, has a remarkable anti-glare effect, and is excellent in impact resistance, and thus is suitable as a lens for sunglasses, goggles and the like.

[Conventional technology]

The use of sunglasses and goggles with a polarization function is rapidly increasing in the fields of leisure and sports such as fishing, skiing and sunking. Further, sunglasses and goggles using a polycarbonate lens having a function of cutting near infrared rays and ultraviolet rays are widely used.

However, sunglasses, goggles and the like using a polarizing lens made of polycarbonate have not been put to practical use yet.

[Problems that the invention is trying to solve]

Generally, the following methods (1) and (2) are considered as a method of manufacturing a polarizing lens made of polycarbonate.

(1). Laminated on both sides of the polarizing thin layer with a curved molded polycarbonate lens obtained by a conventional manufacturing method such as injection molding.

(2). A curved surface is formed on a laminated body in which polycarbonate films or sheets are laminated on both sides of a polarizing thin layer.

However, in the method (1), the optical distortion of the molded polycarbonate is large, and interference fringes are observed when the polycarbonate is adhered. Further, in the step of adhering the polarizing thin layer to the curved surface, the polarizing thin layer is formed. It has the drawback of being easy to tear and difficult to work. Further, in the method (2), since heating is required in the curved surface processing step, discoloration of the polarizing thin layer is likely to occur, and in the case where there is no discoloration, the shaped curved surface is difficult to be permanently fixed, Furthermore, cracks are likely to occur in the polarizing thin layer due to differences in heat shrinkage between the polycarbonate and the polarizing thin layer.

[Means for solving problems]

The present inventors have conducted intensive studies on a method for solving the drawbacks of the conventional methods as described above, and by setting the type of the polarizing thin layer, the thickness of the laminate, and the heating processing conditions within a specific range, They have found that a good polarizing polycarbonate lens can be obtained, and have completed the present invention.

That is, according to the present invention, a polycarbonate film or sheet is laminated on both sides of a polarizing thin layer in which a dichroic dye is oriented on a polymer film to produce a laminate having a thickness of 0.5 to 2.5 mm. At a temperature of 135 ° C or higher and 30 ° C or higher than the glass transition temperature of the polycarbonate of the laminate, the laminate gradually deforms at a pressure of 1.2 kg / cm ² or less before reaching the glass transition temperature of the polycarbonate. And a curved polycarbonate having a radius of curvature of 80 mm or more.

The polycarbonate film or sheet used for producing the laminate of the present invention may be a normal polycarbonate resin, a transparent polycarbonate resin-based copolymer, or a composition with other resin. In addition, the surface can be thermoformed hard coat, anti-fog coating, infrared reflection or absorption, ultraviolet reflection or absorption,
Those that have been subjected to other functionalization processing are also appropriately selected. Incidentally, these functionalization treatments may of course be performed after the polarizing polycarbonate lens of the present invention is manufactured.

The thickness of the laminate is required to be in the range of 0.5 to 2.5 mm from the viewpoint of workability. If it is less than 0.5 mm, defects such as wrinkles are likely to occur during processing, and if it exceeds 2.5 mm, the laminate should be manufactured. As such, it becomes difficult, and it becomes difficult to process a curved surface with little optical distortion that does not damage the polarizing thin layer.

The polarizing thin layer of the present invention is a polymer film using a dichroic dye, in particular a dichroic dye orientated on polyvinyl alcohol (PVA). The conventional general iodine / PVA type polarizing film is an extremely excellent polarizing thin layer, but it is a laminate with polycarbonate, and when it is heated and shaped, fading occurs and the polarizing property is lost. Therefore, it cannot be used in the present invention.

As the curved surface shaping method for the laminate, vacuum molding, press molding, or the like is applied.

The temperature for shaping is 135 ° C. or higher, and is usually 30% higher than the glass transition temperature of the polycarbonate film of the laminate.
℃ higher temperature, preferably 25 ℃ higher temperature, especially 13
A range of 5 ° C to 160 ° C is preferred.

The upper limit of the temperature is related to the curved surface shaping method, 160 ° C. or less is particularly preferable in the case of vacuum forming, and usually 25 ° C. or more than the glass transition temperature in the case of using a mold on both sides such as press forming. It can be processed at temperatures as high as ~ 30 ° C.

During shaping, the force is applied before the laminate reaches the glass transition temperature of the polycarbonate used for the laminate, in other words, at the same time as the start of heating or before the laminate undergoes significant deformation. The actual amount of force applied to the laminate during deformation of the laminate is 1.2 kg / cm ² or less, preferably 0.01 to 1.1 kg / c
It is in the range of m ² , and after the deformation is completed, the polycarbonate film has a size that does not flow-deform and does not adhere,
It depends on the temperature, and when the temperature is high, the lower pressure side is used, but normally a pressure of 20 kg / cm ² or less can be used.

Here, the magnitude of the force during the deformation of the laminate is 1.2 kg / cm ²
If it exceeds, it becomes preferable because defects such as cracks are likely to occur in the polarizing thin layer due to the stress generated between the polycarbonate film of the laminate and the polarizing thin layer sandwiched therein, and if the pressure is too small, The difference in heat shrinkage between the polycarbonate film and the polarizing thin layer and other factors cause wrinkles and unevenness on the surface of the laminate in addition to shaping along the mold, which is not preferable.

Further, during shaping, if a strong curvature with a radius of curvature of less than 80 mm is performed, cracking of the polarizing thin layer in the laminate, molding defects such as peeling of the adhesive layer are likely to occur, and the radius of curvature is 80 mm or more. There is a need to.

The method for producing a polarized polycarbonate lens of the present invention as described above is particularly suitable as a method for producing a lens for goggles, sunglasses, etc., but naturally, it is used for other purposes, such as a windshield for a motorcycle with a polarization function, and a shield. It can be applied to screens, etc.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples. In the examples, the transmittance is measured using a spectrophotometer (trade name: HITACHI330, manufactured by Hitachi Ltd.).

Single-plate transmittance, parallel transmittance (H ₀ : transmittance when two polycarbonate lenses are superposed so that the molecular orientations of their polarizing thin layers are parallel to each other), orthogonal transmittance (H ₉₀ The transmittance when two polycarbonate lenses are superposed so that the molecular orientations of the polarizing thin layers are perpendicular to each other) is an average value after the visibility correction in the visible region of 400 to 700 nm.

Further, the optical distortion was observed by sandwiching the object between the two polarizing plates or by the appearance of interference fringes generated by superposition with the polarizing plates.

Example 1 A polyvinyl alcohol film (trade name; Kuraray Vinylon # 7500, manufactured by Kuraray Co., Ltd.) was used as chlorantine fast red 0.40 g /, brilliant blue 6B 0.30 g /, direct copper blue 2B 0.30 g /, and primula blue 6G.
Staining was carried out at 35 ° C. for 8 minutes in an aqueous solution containing L 0.30 g / and chrysophenin 0.30 g /.

The dyed film was dipped in an aqueous solution containing 0.30 g of nickel acetate tetrahydrate and 12.2 g / of boric acid for 10 minutes and then stretched uniaxially 5 times in the same solution.

The film was taken out of the liquid, washed with water while maintaining a tension state, dried, and then heat-treated at 110 ° C. for 10 minutes to obtain a polarizing film.

Both sides of this polarizing film were laminated with a polycarbonate sheet with a thickness of 700 μm, and the single plate transmittance was 38.6%.
A laminate having a polarization degree of 97.5% was obtained.

In the atmosphere of 148 ° C., heating of this laminated body was started at the same time as suction was started up to 50 mmHg in 1 minute, vacuum forming was carried out for 6 minutes, and a lens having a radius of curvature R = 90 mm was processed.

The obtained lens has no visible spots, cracks, wrinkles, etc., no optical distortion, and a single plate transmittance of 38.3.
%, The degree of polarization was 97.8%, which was substantially the same as before processing.

Example 2 A good polarizing lens was obtained in the same manner as in Example 1 except that a laminate made of a polycarbonate film having a thickness of 700 μm and subjected to an acrylic hard coat treatment on one side was used as the laminate.

Example 3 A polarizing film was obtained in the same manner as in Example 1 except that the dyeing temperature was 40 ° C. and the dyeing time was 6 minutes, and the same hard coat as in Example 2 was applied to both sides of the polarizing film.
mm polycarbonate sheets were laminated to obtain a laminate having a single plate transmittance of 37.0% and a polarization degree of 98.5%.

This laminate was placed in a spherical mold at 140 ° C and held for 5 minutes, then clamped at a speed of 5 mm / min to a pressure of 10 kg / cm ² to complete molding, and a polycarbonate with a radius of curvature R = 100 mm. Got the lens.

The obtained lens has no visible spots, cracks, wrinkles, etc., no optical distortion, and has a single plate transmittance of 37.1.
%, The degree of polarization was 98.3%, which was substantially the same as before processing.

Comparative Example 1 An iodine-based polarizing thin layer was manufactured by a conventional method, and a laminate having a single plate transmittance of 41.0% and a polarization degree of 99.2% was obtained in the same manner as in Example 2.

When this laminate was used and processed in the same manner as in Example 1, decolorization occurred and an almost transparent lens was obtained.

Comparative Example 2 When a film having a thickness of 0.2 mm laminated on both sides of a polarizing film was used as a laminate and the same lens processing as in Example 3 was carried out, a wrinkled lens was obtained.

[Operation and effect of the invention]

As is clear from the above detailed description of the invention and Examples, Comparative Examples, etc., the polarizing polycarbonate lens of the present invention has little optical distortion and has the original performance of polycarbonate, so that it is suitable for sunglasses, goggles, etc. It is preferably used.

Claims (1)

[Claims] 1. A polycarbonate film or sheet is laminated on both sides of a polarizing thin layer in which a dichroic dye is oriented on a polymer film to produce a laminate having a thickness of 0.5 to 2.5 mm. Before reaching the glass transition temperature of the polycarbonate at a temperature not higher than 30 ° C. higher than the glass transition temperature of the polycarbonate of the laminate above 0 ° C.,
Gradually deformed at a pressure of 1.2 kg / cm ² or less, the radius of curvature is 80 m
A method for manufacturing a polarized polycarbonate lens with little optical distortion, which is characterized by shaping a curved surface of m or more.