WO2023112533A1

WO2023112533A1 - Polarizing sheet

Info

Publication number: WO2023112533A1
Application number: PCT/JP2022/040832
Authority: WO
Inventors: 佑哉松野; 雅幸赤木; 祐香柿沼; 英明木村
Original assignee: 三菱瓦斯化学株式会社; Мｇｃフィルシート株式会社
Priority date: 2021-12-17
Filing date: 2022-10-31
Publication date: 2023-06-22
Also published as: TW202400407A

Abstract

[Problem] To provide a polarizing film obtained by swelling a poly(vinyl alcohol) resin film and uniaxially stretching the swollen film, the polarizing film combining wet heat resistance with heat resistance. [Solution] A polarizing laminate comprising a polarizing film, which is a uniaxially stretched poly(vinyl alcohol) resin film, and transparent plastic sheets disposed on both surfaces of the polarizing film with an adhesive layer interposed therebetween. In the polarizing laminate, ΔEcmc values under the conditions of 55°C, 90%, and 24h and under the conditions of 120°C and 24h are 3.0 or less each, the values being calculated with CIEDE2000 color-difference formula according to ISO/CIE 11664-6:2014.

Description

polarizing sheet

TECHNICAL FIELD The present invention relates to a polarizing film and a polarizing sheet constituting a polarizing lens used for sunglasses, goggles, etc., and a method for producing these. In particular, the present invention relates to a polarizing film excellent in resistance to moist heat and heat, a polarizing sheet using the film, and methods for producing these.

In a polarizing film obtained by adsorbing a dichroic dye to a resin substrate such as polyvinyl alcohol and substantially unidirectionally oriented, as described in the following patent document, a high dichroic ratio is achieved depending on the transmittance and the degree of polarization. A combination of dyes and very low dichroic ratio dyes, or intermediate dichroic ratio dyes, are used to produce polarizing sheets. In these documents, the problem of color tone and transmittance change during bending and injection molding is solved by using a coloring composition with a low dichroic ratio. However, even in optical products using such polarizing films, when exposed to high temperature and high humidity for a long time, deterioration of optical performance, peeling, generation of air bubbles, etc. occur, and defects such as easy warping are still present. There is room for improvement.

WO2014/030611 WO2014/115705

The polarizing property of the polarizing film is realized by a polarizer (a dichroic dye) oriented in the resin film that is the base material by means of stretching or the like during the production of the film. Specifically, a resin film such as polyvinyl alcohol as a base material is swollen with water, then immersed in a water tank containing a dye composition, and then stretched at the same time or later. In the wet production as described above, the polarizing film is subjected to further processes after production, or dried for the purpose of obtaining storage stability to adjust its moisture content. However, a polarizing film using a polyvinyl alcohol resin as a base material has a problem that heat-resistant color change increases, although it is possible to suppress heat-and-moisture color change by adjusting the moisture content at the time of film formation. In addition, when the moisture content is lowered in order to suppress heat-resistant color change, the color change increases in a high-humidity and heat environment, making it difficult to achieve both of these two types of thermal stability.

As described above, it was possible to suppress either one of the color changes of the polarizing sheet due to heat and humidity and the color change due to heat, but it was impossible to suppress both color changes at the same time. rice field. However, as a result of intensive studies aimed at solving the above problems, the present invention uses a high dichroic ratio dye and an extremely low dichroic ratio dye, and controls the moisture content and nickel adsorption amount of the polarizing film. The inventors have found that both the heat-resistant color change can be suppressed at the same time, leading to the present invention.

That is, the present invention provides a polarizing laminate in which transparent plastic sheets are arranged on both sides of a polarizing film made of a uniaxially stretched polyvinyl alcohol resin film via an adhesive layer, wherein the polarizing film contains an organic dye and a metal compound. and boric acid, wherein the metal compound is a metal such as acetate, nitrate, sulfate of a fourth transition metal such as chromium, manganese, cobalt, nickel, copper, zinc, etc. salt, and ΔEcmc calculated by the CIEDE 2000 color difference formula of ISO/CIE 11664-6:2014 at 55 ° C., 90%, 24 h and 120 ° C., 24 h is both 3.0 or less. It is a laminate.

Another embodiment of the present invention is the polarizing laminate in the above embodiment, wherein the metal compound is contained in an amount of 200 ppm to 2500 ppm per 1 g of the polarizing film.

Another embodiment of the present invention is the polarizing laminate according to any one of the above embodiments, wherein the water content of the polarizing film is less than 5% by weight of the polarizing film.

In another embodiment of the present invention, according to any of the above embodiments, the organic dye comprises one or more high dichroic organic dyes having a dichroic ratio of 13 or more and very low dichroic organic dyes having a dichroic ratio of 4 or less. A polarizing laminate composed of a combination with one or more low dichroic organic dyes having a dichroic ratio or substantially no dichroic ratio.

Another embodiment of the present invention is a polarizing lens for sunglasses manufactured from the polarizing laminate according to any one of the above embodiments.

Another embodiment of the present invention is a polarizing film obtained by dyeing a polyvinyl alcohol resin with an organic dye while swelling with water and uniaxially stretching, immersing it in a treatment solution containing a metal compound and boric acid, and drying it. In the manufacturing method of 1, the polarizing film is dried so that the moisture content of the polarizing film is less than 5% by weight.

In another embodiment of the present invention, in the above embodiment, the treatment solution contains the metal compound at a concentration of 1.0 to 0.3 g/L, and the boric acid is contained at a concentration of 5.0 to 3.0 g/L. It is a method that is included in the concentration of L.

Another embodiment of the present invention is a method for producing a polarizing sheet according to any of the above embodiments, comprising bonding a transparent plastic sheet to at least one side of the produced polarizing film via an adhesive layer.

With the present invention, it has become possible to achieve both resistance to moisture and heat and suppression of heat-resistant color change, and it has become possible to manufacture polarizing sheets with little color change even in harsh environments in terms of both temperature and humidity.

The configuration of the present invention will be described below.
The polarizing film is obtained by swelling a resin film as a base material in water, and then impregnating it with a dyeing solution containing the dichroic organic dye of the present invention while stretching in one direction. By dispersing it in an oriented state in a material resin to obtain a film imparted with polarizing properties and a desired color tone.

Polyvinyl alcohols are used as the base resin for the polarizing film used at this time, and the polyvinyl alcohols include polyvinyl alcohol (hereinafter referred to as PVA), PVA with a trace of the acetate structure, and PVA derivatives or Analogues such as polyvinyl formal, polyvinyl acetal, and saponified ethylene-vinyl acetate copolymer are preferred, and PVA is particularly preferred.

The molecular weight of the PVA film is preferably a weight average molecular weight of 50,000 to 350,000, more preferably a molecular weight of 100,000 to 300,000, particularly a molecular weight of 150,000, from the viewpoint of stretchability and film strength. The above is preferable. The stretching ratio for stretching the PVA film is preferably 2 to 8 times, more preferably 3 to 6.5 times, particularly preferably 3.5 to 4.5 times, from the viewpoint of the dichroic ratio and film strength after stretching. Although the thickness of the stretched PVA film is not particularly limited, it is preferably about 20 μm or more and about 50 μm or less because it can be handled without being integrated with a protective film or the like.

A typical manufacturing process when using PVA as a base film is
(1) PVA is swollen in water and washed with water to remove impurities,
(2) while stretching as appropriate,
(3) Dyeing in a dyeing tank,
(4) cross-linking or chelating treatment in a treatment tank with boric acid or a metal compound;
(5) dry;
Manufactured in the process of The steps (2), (3) (and (4) in some cases) may be changed in order, or may be carried out at the same time.

First, in the step (1) of swelling and washing with water, the PVA film, which is easily broken in a dry state at room temperature, is uniformly softened and made stretchable by absorbing water. It is also a step of removing water-soluble plasticizers and the like used in the PVA film manufacturing process, or preliminarily adsorbing additives as appropriate. At this time, the PVA film does not gradually and uniformly swell, and variations always occur. Even in this state, it is important to apply a uniform force that is as small as possible so as to prevent local stretching or insufficient stretching and to suppress the occurrence of wrinkles. Moreover, in this step, it is most desirable to simply swell uniformly, and excessive stretching, etc., causes unevenness and should be avoided as much as possible.

In the step (2), stretching is usually carried out so as to be 2 to 8 times. It is also important that the polarizing film in the present invention has good subsequent workability, so the draw ratio is selected from 3 to 6.5 times, particularly 3.5 to 4.5 times, and the orientation is maintained even in this state. is preferred. In the stretched and oriented state, if the time in water and the time until drying are long, the relaxation of the orientation will progress, so from the viewpoint of maintaining higher performance, the stretching process is set to be shorter. However, after stretching, it is preferable to remove moisture as soon as possible, that is, immediately lead to a drying step and dry while avoiding an excessive heat load. In addition, the draw ratio in this application is a draw ratio based on the original fabric of the polyvinyl alcohol resin film.

Dyeing in step (3) is by adsorption or deposition of a dye onto the polymer chains of the oriented polyvinyl alcohol resin film. This step can be performed before, during, or after uniaxial stretching, and there is no significant difference. However, the interface, which is the highly regulated surface, is the easiest to orient, and it is preferable to select conditions that take advantage of this. The temperature is usually selected from a high temperature range of 40 to 80.degree. C. from the demand for high productivity.

Step (4) is performed to improve heat resistance, water resistance, and organic solvent resistance. The treatment with boric acid improves the heat resistance by cross-linking between PVA chains, but it can be performed before, during or after the uniaxial stretching of the polyvinyl alcohol resin film, and there is no significant change. In addition, the metal compound mainly forms a chelate compound with the dye molecule to stabilize it, which is usually performed after dyeing or at the same time as dyeing.

As the metal compound, there are transition metals belonging to any of the 4th, 5th, and 6th periods that are confirmed to have the heat resistance and solvent resistance effects described above. Metal salts such as acetates, nitrates and sulfates of 4th period transition metals such as chromium, manganese, cobalt, nickel, copper and zinc are preferred from the viewpoint of cost. Among these, compounds of nickel, manganese, cobalt, zinc and copper are more preferable because they are inexpensive and excellent in the above effects, and nickel is particularly preferable.

More specific examples include manganese (II) acetate tetrahydrate, manganese (III) acetate dihydrate, manganese (II) nitrate hexahydrate, manganese (II) sulfate pentahydrate, cobalt (II) acetate tetrahydrate, cobalt (II) nitrate hexahydrate, cobalt (II) sulfate heptahydrate, nickel (II) acetate tetrahydrate, nickel (II) nitrate hexahydrate, Nickel (II) Sulfate Hexahydrate, Zinc (II) Acetate, Zinc (II) Sulfate, Chromium (III) Nitrate Nonahydrate, Copper (II) Acetate Monohydrate, Copper (II) Nitrate Trihydrate and copper (II) sulfate pentahydrate. Any one of these metal compounds may be used alone, or two or more of them may be used in combination.

From the viewpoint of imparting heat resistance and solvent resistance to the polarizing film, the content of the metal compound and boric acid in the polarizing film is 0.2 to 20 mg of the metal compound per 1 g of the polarizing film. Preferably, 0.2 to 2 mg is more preferable. More specifically, the concentration of the metal compound impregnated in the polarizing film is 200 ppm to 2500 ppm, more preferably 200 ppm to 2000 ppm, and still more preferably 400 ppm when measured by the method described in detail in Examples. ~1800 ppm, more preferably 800 ppm to 2300 ppm, more preferably 600 ppm to 1600 ppm. When the concentration of the metal compound is less than 200 ppm, color unevenness tends to occur, and when it exceeds 2500 ppm, a problem arises in moist heat resistance.

As described above, when the polarizing film is impregnated with a metal compound in the treatment tank, a chelate is formed between the dye molecules and the polarizing film, and it is thought that the orientation change of the dye can be suppressed. If a large amount of metal compound is added, the excess metal compound that is not used for chelation reacts with the dye molecules, making it difficult to adjust the color tone. In order to compensate, it is necessary to add a high dichroic dye, so the polarizing film becomes highly oriented in a moist and hot environment, and the color change becomes large. Therefore, by adding an appropriate amount of metal compound necessary for chelate formation, it has become possible to produce a polarizing film that has not only heat stability but also wet heat stability.

In the present invention, the boric acid content is preferably 0.3 to 30 mg, more preferably 0.5 to 10 mg as boron. The composition of the treatment liquid used for the treatment is set so as to satisfy the above contents, and generally the concentration of the metal compound is 0.5 to 30 g/L and the concentration of boric acid is 2 to 20 g/L. preferable.

The content of metal and boron contained in the polarizing film can be analyzed by atomic absorption spectrometry.

As for the temperature, the same conditions as those for dyeing are usually employed, but it is usually selected from 20 to 70°C, preferably 25 to 45°C, more preferably 30 to 40°C, especially 30 to 35°C. Also, the time is usually selected from 0.5 to 15 minutes.

In step (5), the stretched, dyed and optionally dyed uniaxially stretched PVA film treated with boric acid or metal compound is dried. A PVA film exhibits heat resistance corresponding to the amount of water it contains. A decrease in the dichroic ratio occurs.

Drying of the film progresses from the surface, and it is preferable to dry from both surfaces, preferably while removing water vapor by blowing dry air. In addition, as is well known, from the point of avoiding excessive heating, the method of immediately removing the evaporated moisture to promote evaporation is preferable from the point that drying can be performed while suppressing the temperature rise. Air drying is carried out at a temperature of 70° C. or higher, preferably 90° C. to 120° C., for 1 to 120 minutes, preferably 3 to 40 minutes, from the temperature range below which the film does not substantially discolor.

The moisture content of the polarizing film at this stage is preferably 5% or less. In the drying process, it is difficult to make the water content less than 2%, and it is not preferable from the viewpoint of the strength of the polarizing film. A suitable moisture content is 2.5% to 5.0%.

A PVA polarizing film for sunglasses is usually manufactured by the above process.

Since the present invention dyes using a dichroic organic dye composition and a coloring organic dye composition, the upper limit is the transmittance of the PVA polarizing film dyed with the dichroic organic dye composition, and the coloring It is possible to select a wide range of transmittance, with the transmittance of a PVA polarizing film dyed with an organic dye composition being the lower limit.
Further, the color tone is adjusted mainly by the organic dye composition for coloring, and a wide range of color tone can be obtained corresponding to the change of the usage ratio without substantially considering the change of the degree of polarization.

Among the dyes whose dichroic ratio was examined by the method described later, the dichroic organic dyes having a dichroic ratio of 13 or more are specifically exemplified by the following azo dyes, but are particularly limited to these. not a thing Azo dyes are exemplified by trade names, and Color Index Generic Names are given in parentheses.
Summit Supra Yellow BC conc (C.I. Direct Yellow28)
Kayarus Light Yellow F8G (CI Direct Yellow87)
Kayacelon Yellow C-2RL (CI Direct Yellow 164)
Direct Fast Orange S (C.I. Direct Orange 26)
Summit Supra Orange 2GL 125% (CI Direct Orange 39)
Nippon Fast Scarlet GSX (C.I. Direct Red4)
Fast Scarlet 4BS (CI Direct Red23)
Summit Red 4B (C.I. Direct Red81)
Kayarus Supra Blue BWL 143 (C.I. Direct Blue 237)
Kayarus Supra Brown GL 125 (C.I. Direct Brown 195)
Kayarus Supra Brown B2R (CI Direct Brown 209)
Kayarus Supra Brown GTL (C.I. Direct Brown 210)

A direct dye consisting of an azo dye having a sulfonic acid group is preferred from the viewpoint of dyeability to PVA film and heat resistance. In order to obtain the desired color tone of the polarizing film, which is substantially colorless in the present invention, usually three or more kinds of dichroic organic dyes are combined, and each color is directly added to the dyeing solution at a concentration such that a predetermined transmittance is obtained. Dissolve or disperse dyes. In addition to the direct dye, an inorganic salt such as sodium sulfate is appropriately added to the dyeing solution as a dyeing aid.

Among the dyes whose dichroic ratio was examined by the method described later, as an example of an organic dye for coloring that has a dichroic ratio of 4 or less or has substantially no dichroic ratio, specifically, The following azo dyes, mordant dyes, reactive dyes, and acid dyes are exemplified, but are not particularly limited to these. Direct Brilliant Pink B (CI Direct Red9)
Kayarus Light Red F5G (CI Direct Red225)
Direct Light Rose FR (CI Direct Red227)
Summit Supra Turquoise Blue G (C.I. Direct Blue86)
Direct Supra Blue FFRL (C.I. Direct Blue 108)
Kayarus Cupro Green G (CI Direct Green 59)
Direct Fast Black B (C.I. Direct Black 22)
Sunchromine Yellow MR (CI Mordant Yellow 3)
Chrome Yellow AS (CI Mordant Yellow 5)
Chrome Yellow 3R (CI Mordant Yellow 8)
Chrome Yellow PG (CI Mordant Yellow 23)
Chrome Orange FL (CI Mordant Orange29)
Chrome Red B conc. (C.I. Mordant Red7)
Chrome Red 5G (CI Mordant Red19)
Sunchromine Brilliant Violet R conc. (C.I. Mordant Violet 1:1)
Chrome Fine Violet R (C.I. Mordant Violet 1)
Chrome Cyanine BXS (C.I. Mordant Blue 1)
Mordant Blue B 120% (CI Mordant Blue 13)
Chrome Cyanine BLA (C.I. Mordant Blue29)
Mordant Green L (CI Mordant Green 17)
Chrome Green 3B-N (CI Mordant Green28)
Mordant Brown KS (C.I. Mordant Brown 15)
Chrome Brown LE (CI Mordant Brown 19)
Chrome Brown RH (CI Mordant Brown 33)
Chrome Black P2B (C.I. Mordant Black7)
Chrome Black PLW (CI Mordant Black 9)
Chrome Black ET-1 (C.I. Mordant Black 11)
Chrome Navy CR 158% (CI Mordant Black 17)
Chrome Light Gray G (C.I. Mordant Black38)
Chrome Bordeaux FB
Alizarine Chrome Brilliant Blue BL
Chrome Blue 2G
Sumifix Yellow GR 150% (CI Reactive Yellow 15)
Lanasol Yellow 4G (CI Reactive Yellow 39)
Sumifix Golden Yellow GG (A) 150% (CI Reactive Yellow76)
Kayacion Yellow E-S4R (C.I Reactive Yellow84)
Novacron Yellow P-6GS gran (CI Reactive Yellow 95)
Kayacion Yellow E-SNA (CI Reactive Yellow 102)
Kayacion Yellow E-SN4G (CI Reactive Yellow 105)
Drimarene Yellow K-2R CDG (CI Reactive Yellow 125)
Sumifix Supra Yellow 3RF 150% gran (C.I Reactive Yellow 145)
Sumifix Supra Brilliant Yellow 3GF 150% gr (C.I Reactive Yellow 167)
Novacron Yellow CR (C.I Reactive Yellow 168)
Novcron Yellow C-5G (C.I Reactive Yellow 175)
Kayacion Yellow CF-3RJ 150
Kayacion Yellow E-CM
Procion Orange PX-RN (CI Reactive Orange 5)
Remazol Brilliant Orange 3R Special (CI Reactive Orange 16)
Levafix Yellow E-3RL gran (CI Reactive Orange 30)
Levafix Orange E-3GA gran (CI Reactive Orange 64)
Remazol Golden Yellow RNL gran 150% (CI Reactive Orange 107)
Drimaren Rubinol X3LR CDG (C.I. Reactive Red55)
Brilliant Red G SPL (C.I. Reactive Red 112)
Brilliant Red 7BF Liq 25% (C.I. Reactive Red 114)
Lanasol Red 2G (CI Reactive Red 116)
Levafix Scarlet E-2GA gran (C.I. Reactive Red124)
Levafix Brilliant Red E-4BA gran (CI Reactive Red158)
Levafix Brilliant Red E-6BA gran (CI Reactive Red159)
Remazol Brilliant Red F3B gran (C.I. Reactive Red180)
Supra Brilliant Red 3BF 150% gran (C.I. Reactive Red195)
Remazol Red RB 133% (CI Reactive Red 198)
Supra Scarlet 2GF 150G (C.I. Reactive Red222)
Novacron Red P-6B Gran. 150%
Novacron Red C-2G
Kayacion Violet A-3R (C.I. Reactive Violet 1)
Remazol Brill. Violet 5R (C.I. Reactive Violet 5)
Drimaren Violet K-2RL CDG (CI Reactive Violet 33)
Remazol Brill. Blue RN (CI Reactive Blue 19)
Sumifix Turquoise Blue G(N) conc. (C.I. Reactive Blue21)
Novacron Blue P-3R IN (C.I. Reactive Blue49)
Lanasol Blue 3R (CI Reactive Blue 50)
Drimarene Blue X-3LR CDG (C.I. Reactive Blue52)
Lanasol Blue 3G (CI Reactive Blue 69)
Novacron Turquoise P-GR 150% (CI Reactive Blue72)
Dimarene Navy X-RBL CDG (C.I. Reactive Blue79)
Lanasol Blue 8G-01 150% (CI Reactive Blue 185)
Drimarene Blue K-2RL CDG (C.I. Reactive Blue 209)
Sumifix Supra Blue BRF 150% gran. (C.I. Reactive Blue221)
Sumifix Supra Navy Blue BF gran. (C.I. Reactive Blue222)
Sumifix Supra Turquoise Blue BGF(N) (C.I. Reactive Blue231)
Novacron Blue CR (C.I. Reactive Blue235)
Kayacion Blue CF-GJ150
Kayacion Blue CF-BL
Kayacin Marine E-CM
Kayacion Navy E-CM
Sumifix Supra Navy Blue 3GF 150% gran
Levafix Brown E-2R gran (CI Reactive Brown 19)
Novacron Brown P-6R Gran. 150
Remazol Black BN 150% (C.I. Reactive Black5)
Remazol Black RL 133% (CI Reactive Black 31)
Remazol Deep Black N 150% (CI Reactive Black 31)
Acid Quinoline Yellow WS H/C (C.I. Acid Yellow 3)
Kayacyl Yellow GG 80 (C.I. Acid Yellow 17)
Tartrazine NS conc (CI Acid Yellow 23)
Suminol Fast Yellow R conc. (C.I. Acid Yellow 25)
Kayanol Milling Yellow O (C.I. Acid Yellow 38)
Suminol Milling Yellow MR (C.I. Acid Yellow 42)
Aminyl Yellow E-3GL (C.I. Acid Yellow 49)
Suminol Fast Yellow G (B) (C.I. Acid Yellow 61)
Erionyl Yellow B-4G (C.I. Acid Yellow79)
Kayanol Yellow N5G (C.I. Acid Yellow 110)
Lanyl Yellow G ex cc (C.I. Acid Yellow 116)
Kayakalan Yellow GL 143 (C.I. Acid Yellow 121)
Kayanol Milling Yellow 5GW (CI Acid Yellow 127)
Lanacron Yellow N-2GL KWL (C.I. Acid Yellow 129)
Erionyl Golden Yellow MR-02 (C.I. Acid Yellow 151)
Tectilon Yellow 2G 200% (CI Acid Yellow 169)
Lanacron Yellow S-2G-01 KWL (C.I. Acid Yellow 220)
Telon Yellow RLN micro (C.I. Acid Yellow 230)
Tectilon Yellow 3R 200% (CI Acid Yellow 246)
Chuganol Fast Yellow 5GL (CI Acid Yellow 40:1)
Solar Orange (CI Acid Orange 7)
Solar Light Orange GX (C.I. Acid Orange 10)
Chuganol Milling Brown 5R (C.I. Acid Orange 51)
Chuganol Milling Orange SG (CI Acid Orange 56)
Kayanol Yellow N3R (C.I. Acid Orange 67)
Aminyl Yellow E-3RL (C.I. Acid Orange 67)
Lanyl Orange R 200% (CI Acid Orange 88)
Chuganol Milling Orange GSN 150% (CI Acid Orange 95)
Suminol Milling Orange GN (N) (C.I. Acid Orange 95)
Isolan Orange K-RLS (C.I. Acid Orange 107)
Telon Orange AGT 01 (C.I. Acid Orange 116)
Lanyl Orange 2R e/c (C.I. Acid Orange 120)
Supralan Orange S-RL (C.I. Acid Orange 166)
Lanasyn Yellow M-2RL 180 (C.I. Acid Orange 180)
Nylosan Orange NRL 250 (C.I. Acid Orange 250)
Lanasyn Orange M-RL p
Silk Scarlet (CI Acid Red9)
Brilliant Scarlet 3R conc. (C.I. Acid Red 18)
Acid Rhodamine G Conc (C.I. Acid Red50)
Acid Rhodamine B Conc (C.I. Acid Red52)
Chugacid Red FCH (C.I. Acid Red73)
Chugacid Rubinol 3B 200% (C.I. Acid Red80)
Rocceline NS conc. 120% (CI Acid Red88)
Chuganol Anthracene Red G (CI Acid Red97)
Suminol Fast Red G (B) (C.I. Acid Red 118)
Suminol Milling Brilliant Red 3BN (N) conc. (C.I. Acid Red 131)
Lanyl Red GG (CI Acid Red 211)
Lanyl Red B (CI Acid Red 215)
Lanasyn Bordeaux M-RLA200 (C.I. Acid Red217)
Suminol Milling Brilliant Red B conc. N (CI Acid Red 249)
Aminyl Red E-3BL (CI Acid Red257)
Telon Red M-BL (CI Acid Red260)
Chugai Aminol Fast Pink R (C.I. Acid Red289)
Nylosan Red N-2RBL SGR (C.I. Acid Red336)
Telon Red FRL micro (C.I. Acid Red337)
Lanasyn Red MG (C.I. Acid Red399)
Kayakalan Red BL
Nylosan Red EBL SGR 180
Kayanol Milling Red BW
Kayanol Milling Violet FBW (C.I. Acid Violet48)
Erionyl Red B-10B-01 (C.I. Acid Violet54)
Chugai Aminol Fast Violet F6R (CI Acid Violet 102)
Acid Pure Blue VX (C.I. Acid Blue 1)
Acid Brilliant Blue AF-N (C.I. Acid Blue7)
Chugacid Light Blue A (C.I. Acid Blue 25)
Kayanol Blue N2G (C.I. Acid Blue 40)
Nylosan Blue E-GL p 250 (C.I. Acid Blue 72)
Chuganol Blue 6B 333% (C.I. Acid Blue 83)
Chuganol Blue G 333% (C.I. Acid Blue90)
Kayanol Navy Blue R (C.I. Acid Blue 92)
Suminol Milling Brilliant Sky Blue SE (N) (C.I. Acid Blue 112)
Suminol Milling Cyanine 5R (N) (C.I. Acid Blue 113)
Kayanol Milling Blue GW (C.I. Acid Blue 127)
Lanyl Brilliant Blue G ex cc (C.I. Acid Blue 127:1)
Kayanol Blue NR (C.I. Acid Blue 129)
Kayanol Milling Blue BW (C.I. Acid Blue 138)
Kayanol Milling Blue 2RW (C.I. Acid Blue 140)
Lanyl Blue 3G ex conc (C.I. Acid Blue 171)
Nylosan Blue N-GL 150 (C.I. Acid Blue 230)
Tectilon Blue 6G 200% (C.I. Acid Blue 258)
Telon Blue AFN (CI Acid Blue 264)
Tectilon Blue 4R-01 200% (C.I. Acid Blue 277:1)
Nylosan B Blue N-FL SGR180 (C.I. Acid Blue278)
Nylosan Blue N-5GL SGR 200 (C.I. Acid Blue 280)
Kayalax Navy R (C.I. Acid Blue 300)
Nylosan Blue N-BLN (C.I. Acid Blue 350)
Lanacron Blue N-3GL
Acid Green V (CI Acid Green 16)
Chuganol Cyanine Green G (CI Acid Green 25)
Suminol Milling Brown 5R (C.I. Acid Brown 51)

The above dyes are not commonly referred to as dichroic dyes. The pigments (dyes) exhibiting a high dichroic ratio are described in patent documents, etc., and the dichroic ratio can be known. However, the present inventors have not found a patent document or the like describing the dichroic ratio of the organic dye for coloring of the present application, probably because the dichroic ratio was never used, or because there was no meaning to use it. . Therefore, the coloring organic dyes of the present application described above are examples of those readily identified in the following method of dyeing PVA films using known dyes (not known to have high dichroic ratios).

The dichroic ratio is determined by the following method of dyeing a PVA film using these dyes. Here, for example, when the degree of polarization is targeted to be 99% or more, the dichroic ratio of the coloring organic dye contributes to the direction of increasing the degree of polarization, but changes within the above range are problematic. not. On the other hand, for example, in a polarizing lens having a degree of polarization of about 90%, when the dichroic ratio of the coloring organic dye increases, that is, when the dichroic ratio approaches 4 in the present application, the degree of polarization of the obtained polarizing film becomes higher than the desired value. In any case, those that show a smaller dichroic ratio when dyed are preferable because the change in the degree of polarization due to coloring is smaller and the change in color tone during thermoforming is also smaller.

In addition, the dichroic ratio of the dichroic organic dye or the organic coloring dye in the present invention means that the dichroic ratio value measured at 600 nm in the polarizing film manufactured by dyeing with iodine is 60 or more. It refers to the value measured at the maximum absorption wavelength in a polarizing film manufactured using a dichroic organic dye instead of iodine.

Next, on both sides of the present colored polarizing film, a protective layer made of a transparent plastic sheet is usually attached via an adhesive layer to obtain the polarizing sheet of the present invention. The transparent plastic sheet usually has a thickness of 0.1 to 1 mm, and may be a single-layered sheet or a multi-layered sheet formed by co-extrusion, such as a co-extruded sheet of aromatic polycarbonate/polyacrylate. Further, in the present invention, it is preferable that the surface which is the concave side in the bending process and the injection molding resin side is made of aromatic polycarbonate. In addition, the polarizing sheet of the present invention (hereinafter referred to as the present polarizing sheet) is usually punched into individual lens shapes with protective films attached to both surfaces, and then subjected to heat bending to protect the surface. The film is peeled off and mounted in an injection mold to form an injection molded polarizing lens integrated with the injection molded aromatic polycarbonate.

Examples of the resin for the transparent plastic sheet include transparent resins composed of aromatic polycarbonates, amorphous polyolefins, polyacrylates, polysulfones, acetylcellulose, polystyrene, polyesters, polyamides, and mixtures thereof. Among these, there is acetyl cellulose, which is essential in the production of the most versatile polarizing film. Aromatic polycarbonate resins are preferable for their properties such as mechanical strength and impact resistance. Examples thereof include acrylate and polyamide, and polyacrylate and polyamide are exemplified in terms of dyeability after lens molding.

Aromatic polycarbonate sheets are made of 2,2-bis(4-hydroxyphenyl)alkane and 2,2-(4-hydroxy-3,5-dihalogenophenyl) from the viewpoint of film strength, heat resistance, durability and bending workability. ) A polymer produced by a known method from a bisphenol compound represented by alkane is preferable, and the polymer skeleton may contain a structural unit derived from a fatty acid diol or a structural unit having an ester bond. Aromatic polycarbonates derived from ,2-bis(4-hydroxyphenyl)propane are preferred.

The aromatic polycarbonate preferably has a viscosity average molecular weight of 12,000 to 40,000, more preferably 20,000 to 35,000. In addition, aromatic polycarbonates have a large photoelastic constant and tend to generate colored interference fringes due to birefringence due to stress and orientation. Therefore, it is preferable to make the colored interference fringes invisible by providing a large retardation value in advance. It is preferable to The higher the retardation value, the less colored interference fringes can be seen. However, the value of the retardation value represents the degree of orientation and the magnitude of the residual stress, and the higher the retardation value, the lower the accuracy of the surface shape. These colored interference fringes can be seen with the human eye only after they pass through the polarizing film. Therefore, the effect of the high retardation sheet is due to its use on the light incident side of the polarizing film, that is, on the side opposite to human eyes.

Polyamide resins include those known as transparent polyamide resins for lenses, and have a heat distortion temperature in the range of 100 to 170 ° C., which is an index of heat resistance, aromatic polyamide resins, alicyclic polyamide resins, aliphatic polyamides. Resins, and copolymers thereof, and alicyclic polyamide resins are preferable from the balance of mechanical strength, chemical resistance, transparency, etc., but two or more polyamide resins may be combined. . Examples of such polyamide resins include GLILAMID TR FE5577, XE 3805 (manufactured by EMS), NOVAMID X21 (manufactured by Mitsubishi Engineering-Plastics), and Toyobo Nylon T-714E (manufactured by Toyobo).

The (meth)acrylic resin is a homopolymer of various (meth)acrylic acid esters represented by polymethyl methacrylate (PMMA) and methyl methacrylate (MMA), or PMMA or MMA and one or more other monomers. and may be a mixture of a plurality of these resins. Among these, a (meth)acrylate containing a cyclic alkyl structure, which is excellent in low birefringence, low hygroscopicity and heat resistance, is preferable. Examples of such (meth)acrylic resins include Acrypet (manufactured by Mitsubishi Rayon), Delpet (manufactured by Asahi Kasei Chemicals), and Parapet (manufactured by Kuraray).

Adhesives used to attach the transparent plastic sheets to both sides of the colored polarizing film include polyvinyl alcohol resin materials, acrylic resin materials, urethane resin materials, polyester resin materials, melamine resin materials, and epoxy resin materials. materials such as silicone-based materials can be used.

When an aromatic polycarbonate sheet is used, a two-liquid type consisting of a polyurethane prepolymer, which is a urethane resin-based material, and a curing agent is used, particularly in terms of the transparency of the adhesive layer itself or when it is adhered, and the adhesiveness to the aromatic polycarbonate sheet. thermosetting urethane resin is preferred. The aromatic polycarbonate polarizing sheet used in the colored polarizing lens suitable for sunglasses of the present invention is not limited to the layer structure described above, and the adhesive for bonding the polarizing film and the transparent protective layer contains a photochromic dye. A polarizing sheet having a dimming function, which is produced using a dissolved adhesive, may also be used.

The protective layer of the present invention is selected from suitable processing conditions that allow selection of processing conditions that do not substantially impair the function of the functional layer. For example, when a polyester-based super-multilayer selective reflection film is used in combination as a functional layer, a multi-layer sheet is produced in order to make the thickness of one layer of this super-multilayer selective reflection film 1/4λ. A so-called Kintaro-ame manufacturing method is used in which the film is stretched repeatedly as appropriate to obtain a predetermined optical thickness. As a result, it is essential to select processing conditions such as temperature and time that substantially do not cause relaxation from the stretched state during the processing time while maintaining the functionality.

Next, the polarizing sheet is punched into individual lens shapes, and then subjected to bending. Processing into individual lens-shaped products is usually performed by punching a plurality of lens-shaped products using a punching blade composed of a Thomson blade for reasons of productivity. The shape of the individual lens-shaped product is appropriately selected according to the shape of the final product (sunglasses, goggles, etc.). A standard lens-shaped product for binocular use is a disk with a diameter of 80 mm or a slit shape obtained by cutting both ends of the disk with the same width in the direction perpendicular to the polarization axis. In addition, as mentioned above in the selection of the type of transparent plastic sheet for the protective layer used in the present polarizing sheet, the bending process causes deterioration of the layer that exhibits the functionality of the present polarizing sheet including the colored polarizing film of the present invention. It is determined by the condition that it does not substantially occur.

When used as an injection polarizing lens, the aromatic polycarbonate polarizing sheet is bent along the mold surface used for injection molding. When using this polarizing sheet with a protective layer made of aromatic polycarbonate with a high retardation sheet, the polarizing film tends to crack along the stretching direction during bending, so-called film breakage, so it is necessary to select conditions that suppress the occurrence of these. There is The mold temperature in bending the aromatic polycarbonate polarizing sheet is preferably a temperature below the glass transition temperature of the aromatic polycarbonate used. It is preferably at least 50° C. lower than the glass transition point, and more preferably at least 40° C. lower than the glass transition point and less than 5° C. lower than the glass transition point.

Then, an aromatic polycarbonate resin is injected to form an injection polarizing lens. Processing conditions for injection molding must be such that lenses with excellent appearance can be produced. From this point of view, injection conditions such as injection pressure, holding pressure, metering, molding cycle, etc. are selected so that a lens molded product with a high filling rate can be obtained within a range that does not produce burrs. is the temperature of 260 to 320° C., which is selected as appropriate. In addition, the mold temperature is selected from a temperature not less than 100°C lower than the glass transition temperature of the aromatic polycarbonate resin and less than the glass transition point, preferably not less than 80°C lower than the glass transition temperature and less than 15°C lower than the glass transition point. In particular, it is preferably at least 70° C. lower than the glass transition temperature and less than 25° C. lower than the glass transition temperature.

Then, a hard coat treatment is applied. There are no particular restrictions on the material or processing conditions of the hard coat, but it has excellent appearance and adhesion to the underlying aromatic polycarbonate, or to the subsequently coated inorganic layers such as the mirror coat and antireflection coat. There is a need. Further, the firing temperature is preferably 50°C lower than the glass transition temperature of the aromatic polycarbonate used in the aromatic polycarbonate polarizing sheet and lower than the glass transition point, particularly 40°C lower than the glass transition point or higher than the glass transition point. The temperature is around 120° C., which is less than 15° C. lower, and the time required for firing the hard coat is generally between 30 minutes and 2 hours.

Hereinafter, the details of the present invention will be described based on examples.

(Example 1)
a) Preparation of polarizing film Polyvinyl alcohol (trade name: VF-PS#7500, manufactured by Kuraray Co., Ltd.) was swelled in water at 35°C for 270 seconds and stretched twice.
In this embodiment, the swelling treatment step was performed in two water tanks, but one water tank or three or more water tanks may be used depending on the manufacturing environment.

Subsequently, dyeing was carried out in an aqueous solution at 35° C. containing a dyeing composition having the following composition and 10 g/L of anhydrous sodium sulfate. Among the following dyes, C.I. I. Direct. Orange 39 and C.I. I. Direct. Red 81 is a high dichroic dye and C.I. I. Direct. Blue 78, Kayacion Blue CF-GJ 150, C.I. I. Mordant Yellow 8 and C.I. I. Acid Red 57 is what is called a low dichroic ratio dye. In this embodiment, the dyeing treatment step was performed in two water tanks, but one water tank or three or more water tanks may be used depending on the manufacturing environment.
・C. I. Direct. Orange 39 0.3g/L
・C. I. Direct. Red 81 0.1g/L
・C. I. Direct. Blue 78 0.3g/L
・Kayacion Blue CF-GJ 150 0.2g/L
・C. I. Mordant Yellow 8 0.2g/L
・C. I. Acid Red 57 0.1g/L

Subsequently, in this process of treating the dyed film, the film exiting the bath of the dyeing composition first enters the treatment bath 1 of the treatment process. After that, it goes out into the air once and then passes through the processing tank 2 . Treatment tanks 1 and 2 are filled with an aqueous solution maintained at 40-45° C. containing 0.5 g/L nickel acetate (Ni) and 4.4 g/L boric acid. The dyed film was immersed in this aqueous solution and stretched to a final magnification of 4.0-4.5 times.

The polarizing film pulled up from the treatment tank 2 was then heat-treated at 80 to 89° C. for 3 minutes under tension. The dried polarizing film was stored in a low humidity storage kept at 25° C. and about 10% until the next step.

b) Measurement of Ni in polarizing film Quantitative analysis of Ni was carried out using an atomic absorption spectrophotometer (AA-6300) manufactured by Shimadzu Corporation. 10 to 15 mg of the polarizing film prepared above was collected, dissolved in a 60% nitric acid aqueous solution at 120 ° C., and a calibration curve was obtained by diluting a 1000 ppm nickel standard solution (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) with a 60% nitric acid aqueous solution. was prepared, and the amount of Ni adsorbed to the polarizing film was measured.

c) Measurement of water content in polarizing film A halogen moisture meter (MOC63u) manufactured by Shimadzu Corporation was used to measure the water content in the polarizing film. 0.6 g of the polarizing film produced according to the description of Examples and Comparative Examples was sampled, and the moisture content was calculated from the dry weight after 10 minutes at 150° C. and the weight before measurement using the halogen moisture meter described above.

d) Preparation of polarizing sheet A thermosetting polyurethane adhesive was applied to the polarizing film obtained above, and a protective layer was laminated thereon. A protective layer was similarly laminated on the other side of the polarizing film to prepare a polarizing sheet. Bisphenol A type polycarbonate (Mitsubishi Engineering-Plastics Iupilon E-2000) was used for the protective layer.

e) Environmental Test Humidity and Heat Resistance Test The polarizing sheet prepared by the above procedure was placed in a constant temperature and humidity chamber at 55° C. and 90% for 24 hours, and the color tone before and after the test was measured with a spectrophotometer to calculate ΔEcmc. For the convenience of carrying out the test, the conditions for the heat and humidity resistance test in this example are set to be harsher and shorter than the actual storage conditions.
Heat resistance test The polarizing sheet prepared by the above procedure was placed in a constant temperature and humidity chamber at 120°C for 24 hours, and the color tone before and after the test was measured with a spectrophotometer to calculate ΔEcmc. The conditions for the heat and humidity resistance test in this example are intended to imitate the high heat conditions in which the product is actually manufactured for the convenience of conducting the test, but the test conditions were optimized for repetition. be.
ΔEcmc measurement method The color tone of the samples subjected to the above moisture and heat resistance test and heat resistance test was measured using a spectrophotometer (UV-3600) manufactured by Shimadzu Corporation, and calculated using the CIEDE2000 color difference formula of ISO/CIE 11664-6:2014. The color difference was calculated. In the present invention, products with a ΔEcmc of 3 or less were defined as acceptable products in consideration of actual products.
ΔEcmc=[(ΔL ^* /LS _L ) ² +(ΔC ^* ab/cS _c ) ² +(ΔH ^* ab/S _H ) ² ] ^1/2
The lightness L ^* value is the lightness of the L ^* a ^* b ^* color system. Chroma C ^* value is C ^* =[(a ^* ) ² +(b ^* ) ² ] ^1/2 Hue angle H ^* value is H ^* =tan ⁻¹ [(a ^* )/(b ^* ) ]

(Example 2)
A polarizing film was prepared and tested in the same manner as in Example 1, except that the nickel acetate concentration in the treatment tanks 1 and 2 was 0.3 g/L.

(Example 3)
A polarizing film was prepared and tested in the same manner as in Example 1, except that the nickel acetate concentration in the treatment tanks 1 and 2 was 0.7 g/L.

(Example 4)
A polarizing film was produced in the same manner as in Example 3, except that the heat treatment temperature was 80 to 95°C.

(Example 5)
A polarizing film was produced in the same manner as in Example 4, except that 0.5 g/L of nickel acetate was added only to treatment tank 1, and only boric acid was added to treatment tank 2 without nickel acetate.

(Example 6)
A polarizing film was produced in the same manner as in Example 5, except that the heat treatment temperature was 80 to 100°C.

(Example 7)
A polarizing film was produced in the same manner as in Example 6, except that the heat treatment temperature was set to 80 to 95° C., and after passing through treatment tanks 1 and 2, a washing step with pure water at 40° C. was added.

(Example 8)
A polarizing film was produced in the same manner as in Example 7, except that the boric acid concentration was 6.6 g/L.

(Comparative example 1)
A polarizing film was produced in the same manner as in Example 1, except that the temperatures of the treatment tanks 1 and 2 were 35° C. and nickel acetate was 2.3 g/L.

(Comparative example 2)
A polarizing film was produced in the same manner as in Comparative Example 1, except that the temperatures of the treatment tanks 1 and 2 were set to 40° C., nickel acetate was not added, and only 4.4 g/L of boric acid was used.

(Comparative Example 3)
・C. I. Direct. Orange 39 1.1g/L
・C. I. Direct. Red 81 0.8g/L
・C. I. Direct. Blue 78 1.0 g/L
The above three types of dyes were used in the dyeing process. In addition, the temperature of the treatment tanks 1 and 2 was 35 ° C., nickel acetate was 2.3 g / L, boric acid was 4.4 g / L, and the heat treatment temperature was 90 to 110 ° C. The same polarizing film as in Comparative Example 1 was used. was made.

(Comparative Example 4)
A polarizing film was produced in the same manner as in Comparative Example 3 except that the temperatures of the treatment tanks 1 and 2 were set to 55°C and the heat treatment temperature was set to 70 to 80°C.

(Comparative Example 5)
A polarizing film was produced in the same manner as in Comparative Example 3, except that the heat treatment temperature was changed from 60 to 70°C.

Table 1 below shows the evaluation results of the examples and comparative examples prepared as described above.

- indicates no data.

As shown in Table 1, the polarizing sheet of each example satisfies the condition that both the wet heat color change and the heat color change ΔEcmc are 3.0 or less, and it is possible to produce a polarizing sheet having a good appearance. did it. On the other hand, in the polarizing sheets of the respective comparative examples, ΔEcmc of either one of the heat and humidity color change and the heat color change may be 3.0 or less, but both cannot be satisfied at the same time. Also, defects occurred in the appearance, and a polarizing sheet with a good appearance could not be produced.

In a polarizing film dyed with a dyeing composition containing a high dichroic dye and a low dichroic dye, it has become possible to produce a polarizing film having good wet heat resistance and good heat resistance. The polarizing film according to the present invention is more resistant to discoloration than conventional polarizing films, both under environmental influences during storage and in an environment where the film is exposed to high heat for a short period of time during processing. In addition, it has become possible to provide a method for manufacturing a polarizing film that can significantly reduce the amount of metal compounds, particularly nickel, used in the manufacturing process of the polarizing film.

Claims

A polarizing laminate in which a transparent plastic sheet is arranged on both sides of a polarizing film made of a uniaxially stretched polyvinyl alcohol resin film via an adhesive layer,
The polarizing film is a polyvinyl alcohol resin film containing an organic dye, a metal compound and boric acid,
The metal compound is any one or more of metal salts such as acetates, nitrates and sulfates of fourth period transition metals such as chromium, manganese, cobalt, nickel, copper and zinc, A polarizing laminate whose ΔEcmc calculated by the CIEDE2000 color difference formula of ISO/CIE 11664-6:2014 at 24 hours and at 120° C. for 24 hours is both 3.0 or less.
The polarizing laminate according to claim 1, wherein the metal compound is contained at 200 ppm to 2500 ppm per 1 g of the polarizing film.
The polarizing laminate according to claim 1 or 2, wherein the water content of the polarizing film is less than 5% by weight of the polarizing film.
The organic dye comprises one or more highly dichroic organic dyes having a dichroic ratio of 13 or more and one or more very low dichroic organic dyes having a dichroic ratio of 4 or less or substantially no dichroic ratio. 4. The polarizing laminate according to any one of claims 1 to 3, which is combined with a low dichroic organic dye.
A polarized lens for sunglasses manufactured from the polarized laminate according to any one of claims 1 to 4.
A polyvinyl alcohol resin is dyed with an organic dye while being swollen with water and uniaxially stretched, immersed in a treatment solution containing a metal compound and boric acid, and dried in a method for producing a polarizing film, wherein the drying of the polarizing film. In the above, the method for producing a polarizing film, wherein the polarizing film is dried so that the moisture content is less than 5% by weight.
7. The method of claim 6, wherein the treatment solution contains the metal compound at a concentration of 1.0 to 0.3 g/L and the boric acid at a concentration of 5.0 to 3.0 g/L. .
A method for producing a polarizing sheet, comprising laminating a transparent plastic sheet via an adhesive layer on at least one side of the polarizing film produced by the method according to any one of claims 6 and 7.