JP6591962B2 - Manufacturing method of polarizing plate - Google Patents

Description

  The present invention relates to a method for producing a polarizing plate in which a protective film is bonded to one surface of a polarizing film.

  The polarizing plate is widely used as a polarized light supplying element and a polarized light detecting element in a display device such as a liquid crystal display device. As a polarizing plate, the thing of the structure which bonded the protective film to the polarizing film using the adhesive agent is common.

  With the market demand for polarizing plate thinning, various configurations of polarizing plates that can realize this have been proposed, and one of the representative examples is that a protective film is bonded to only one side of the polarizing film. It is a single-sided protective polarizing plate [for example, Unexamined-Japanese-Patent No. 2009-109860 (patent document 1)].

JP 2009-109860 A

  In manufacturing the single-sided protective polarizing plate, in order to temporarily protect the other surface of the polarizing film to which the protective film is not bonded, while the protective film is bonded to one surface of the polarizing film via an adhesive layer, In general, a peelable release film is laminated on the other surface. This release film is peeled and removed in a subsequent step such as a step of bonding the single-side protective polarizing plate to, for example, a liquid crystal cell.

  However, in the conventional method for producing a single-sided protective polarizing plate, when the temperature in the drying process after the protective film is bonded to the polarizing film is high, the release film is wrinkled and comes into contact with the roll. There was a problem that the stress was concentrated and the polarizing film was broken.

  Then, the objective of this invention is providing the method which can manufacture a single-sided protective polarizing plate, suppressing the fracture | rupture of a polarizing film.

The present invention provides the following method for producing a polarizing plate.
[1] A first film in which a protective film is bonded to one surface of a polarizing film via a water-based adhesive layer, and a release film is stacked on the other surface of the polarizing film via a layer made of a volatile liquid. Process,
A second step of drying the aqueous adhesive layer by heating and volatilizing the volatile liquid;
The manufacturing method of a polarizing plate containing.

[2] The method for producing a polarizing plate according to [1], wherein at least one of the protective film and the release film has a moisture permeability of 400 g / m ² · 24 hr or more.

  [3] The method for producing a polarizing plate according to [1] or [2], wherein the release film has a shrinkage rate of 0.15% or less when heated at 80 ° C. for 5 minutes.

  [4] The method for producing a polarizing plate according to any one of [1] to [3], wherein a contact angle of the surface on the polarizing film side of the release film with respect to the volatile liquid is 50 to 80 °.

  [5] The method for producing a polarizing plate according to any one of [1] to [4], wherein a contact angle of the release film side surface of the polarizing film with respect to the volatile liquid is 50 to 110 °.

  According to the production method of the present invention, a single-sided protective polarizing plate can be produced while suppressing breakage of the polarizing film.

It is a schematic sectional drawing which shows the basic layer structure of a single-sided protection polarizing plate. It is a schematic sectional drawing which shows another example of a single-sided protective polarizing plate. It is a schematic sectional drawing which shows another example of a single-sided protective polarizing plate. It is a schematic sectional drawing which shows the layer structure of the double-sided protective polarizing plate which can be obtained using a single-sided protective polarizing plate. It is a side view which shows typically an example of the manufacturing method of the single-sided protection polarizing plate which concerns on this invention, and a manufacturing apparatus used therewith.

  The present invention relates to a method for producing a single-side protective polarizing plate. In the present invention, the “single-sided protective polarizing plate” is a polarizing plate in which a protective film is bonded to only one side of the polarizing film, and this protective film is usually bonded to the polarizing film via an adhesive layer. The basic structure of a single-sided protective polarizing plate is shown in FIG. Like the single-sided protective polarizing plate 1 shown in FIG. 1, the single-sided protective polarizing plate according to the present invention is bonded to the polarizing film 5 and the first adhesive layer 25 on one surface thereof. The film 20 is included as a basic configuration.

  As will be described in detail later, the production method according to the present invention bonds a protective film (first protective film) to one surface of a polarizing film via a water-based adhesive layer and volatile to the other surface. The first and second steps include a first step of laminating a release film through a liquid layer and a second step of drying the aqueous adhesive layer by heating and volatilizing the volatile liquid. The single-sided protective polarizing plate obtained through the process further comprises a release film 10 laminated on the other surface of the polarizing film 5 like the single-sided protective polarizing plate 2 with a release film shown in FIG.

  The release film 10 is a film that can be peeled off from the polarizing film 5, and is peeled off when necessary (for example, when a single-side protective polarizing plate is bonded to a liquid crystal cell). A single-sided protective polarizing plate 1 is obtained. For example, in order to bond to a liquid crystal cell, the single-sided protective polarizing plate according to the present invention is an adhesive laminated on the other surface of the polarizing film 5 like the single-sided protective polarizing plate 3 with an adhesive layer shown in FIG. An agent layer 30 can be further provided.

  Moreover, the single-sided protective polarizing plate 1 and the single-sided protective polarizing plate 2 with a release film according to the present invention can be suitably used as a production intermediate for a double-sided protective polarizing plate in which protective films are bonded to both sides of the polarizing film. Yes, with reference to FIG. 4, the double-sided protective polarizing plate 4 is obtained by laminating the second protective film 21 via the second adhesive layer 26 on the surface of the polarizing film 5 opposite to the first protective film 20. Can be obtained.

Hereinafter, with reference to FIG. 5, a method for producing a single-side protective polarizing plate according to the present invention will be described in detail with reference to an embodiment. The method for producing a single-sided protective polarizing plate according to the present invention includes the following steps:
(1) The first protective film is bonded to one surface of the polarizing film via an aqueous adhesive layer, and the release film is laminated to the other surface of the polarizing film via a layer made of a volatile liquid. A first step, and (2) a second step of drying the aqueous adhesive layer and volatilizing the volatile liquid by heating,
including.

  FIG. 5: is a side view which shows typically an example of the manufacturing method of the single-sided protection polarizing plate concerning this invention, and a manufacturing apparatus used therewith. In general, as shown in FIG. 5, a polarizing plate such as a single-sided protective polarizing plate is continuously produced as a long product by performing a process in each step while continuously unwinding and transporting a long film. Can be manufactured. However, the production method of the present invention is not limited to continuous production using such a long film, and may be a method using a single wafer film.

(1) First Step Referring to FIG. 5, in this step, first, a roll (rolled product) of a long polarizing film 5, a roll of a long first protective film 20, and a long release film 10. Rolls are prepared, and the film is conveyed while continuously unwinding them using an unshown unwinding device. Each film is conveyed so that the longitudinal direction thereof is the conveyance direction. A guide roll 60 for supporting the traveling film is appropriately provided in the film conveyance path. The arrow in FIG. 5 shows the conveyance direction of a film, or the rotation direction of various rolls. Usually, the conveyance direction (film longitudinal direction) of the polarizing film 5, the conveyance direction (film longitudinal direction) of the 1st protective film 20, and the conveyance direction (film longitudinal direction) of the peeling film 10 are parallel.

  In this step, the first protective film 20 is bonded to one surface of the polarizing film 5 via a first adhesive layer 25 (not shown in FIG. 5) that is a water-based adhesive layer, and the polarizing film 5 The release film 10 is laminated on the other surface through a layer made of the volatile liquid 50. As shown in FIG. 5, the first protective film 20, the polarizing film 5, and the release film 10 are laminated in parallel with each other in the longitudinal direction (conveying direction). It can carry out by pressing the film laminated | stacked with the bonding rolls 40 and 40 from the upper and lower sides by overlapping so that it may pass and between a pair of bonding rolls 40 and 40. FIG.

  At this time, before passing through the bonding rolls 40, 40, the injection device 80, 81 is used to inject the aqueous adhesive 55 between the polarizing film 5 and the first protective film 20, and the polarizing film 5 By injecting the volatile liquid 50 between the release film 10 and the film, a layer made of the water-based adhesive 55 (first adhesive layer 25) and a layer made of the volatile liquid 50 are interposed between the films. Can do.

  The apparatus for interposing the layer made of the water-based adhesive 55 (first adhesive layer 25) and the layer made of the volatile liquid 50 is limited to the injection devices 80 and 81 as shown in FIG. Instead, for example, according to the viscosity of the aqueous adhesive 55 and the volatile liquid 50, such as doctor blade method, wire bar coating method, die coating method, comma coater method, gravure coating method, dip coating method, casting method, etc. The coating method may be selected as appropriate, and the water-based adhesive 55 and the volatile liquid 50 may be applied to the bonding surface of at least one film to be overlaid.

  In the conventional method for producing a single-sided protective polarizing plate, in the process of producing a single-sided protective polarizing plate, the polarizing film is directly laminated without interposing a special layer on the polarizing film surface. There was a problem that the film was easily broken. When a protective film is bonded to one side of a polarizing film via a water-based adhesive layer, in order to obtain a single-sided protective polarizing plate, a step of drying the water-based adhesive layer is required. In particular, the polarizing film was apt to break during this drying step.

  On the other hand, according to the manufacturing method of the present invention in which the release film 10 is laminated on the polarizing film 5 with a layer made of the volatile liquid 50 interposed between the polarizing film 5 and the release film 10, the aqueous adhesive 55 Even in the step (second step) of drying the layer made of (first adhesive layer 25), breakage of the polarizing film 5 can be effectively suppressed. Moreover, interposing the layer which consists of the volatile liquid 50 between the polarizing film 5 and the peeling film 10 also has the effect which suppresses that a wrinkle arises in a single-sided protective polarizing plate during the process of manufacturing a single-sided protective polarizing plate. is there.

  Since the intervening volatile liquid 50 can be volatilized during the step of drying the first adhesive layer 25 (second step), in the manufacturing method of the present invention, the volatile liquid 50 is volatilized and removed. A separate process is not required.

  In bonding the first protective film 20 to the polarizing film 5, the bonding surface of the polarizing film 5 and / or the first protective film 20 is subjected to plasma treatment, corona treatment, and ultraviolet irradiation treatment in order to improve adhesiveness. , Easy adhesion treatment such as flame (flame) treatment and saponification treatment can be performed. Among these, it is preferable to perform plasma treatment, corona treatment or saponification treatment. For example, when the first protective film 20 is made of a cyclic polyolefin-based resin, the bonding surface of the first protective film 20 can be subjected to plasma treatment or corona treatment. Moreover, when the 1st protective film 20 consists of cellulose-ester-type resin, a saponification process can be given to the bonding surface of the 1st protective film 20. FIG. Examples of the saponification treatment include a method of immersing in an alkaline aqueous solution such as sodium hydroxide or potassium hydroxide.

[Polarized film]
The polarizing film 5 can be obtained by adsorbing and orienting a dichroic dye on a uniaxially stretched polyvinyl alcohol-based resin film. As the polyvinyl alcohol resin constituting the polyvinyl alcohol resin film, a saponified polyvinyl acetate resin can be used. Examples of the polyvinyl acetate-based resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers copolymerizable therewith. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and (meth) acrylamides having an ammonium group.

  In the present specification, “(meth) acryl” means at least one selected from acryl and methacryl. The same applies to cases such as “(meth) acryloyl” and “(meth) acrylate”.

  The degree of saponification of the polyvinyl alcohol-based resin can be in the range of 80.0 to 100.0 mol%, preferably in the range of 90.0 to 99.5 mol%, more preferably 94.0. It is in the range of ˜99.0 mol%. When the saponification degree is less than 80.0 mol%, the water resistance and heat-and-moisture resistance of the obtained single-sided protective polarizing plate are lowered. When a polyvinyl alcohol-based resin having a saponification degree exceeding 99.5 mol% is used, the dyeing speed becomes slow, the productivity is lowered, and the polarizing film 5 having sufficient polarization performance may not be obtained.

The degree of saponification is the unit ratio (mol%) of the proportion of acetate groups (acetoxy groups: —OCOCH ₃ ) contained in polyvinyl acetate resin, which is a raw material for polyvinyl alcohol resins, changed to hydroxyl groups by the saponification step. The following formula:
Degree of saponification (mol%) = 100 × (number of hydroxyl groups) / (number of hydroxyl groups + number of acetate groups)
Defined by The saponification degree can be determined according to JIS K 6726 (1994). The higher the degree of saponification, the higher the proportion of hydroxyl groups, and thus the lower the proportion of acetate groups that inhibit crystallization.

  The average degree of polymerization of the polyvinyl alcohol-based resin is preferably 100 to 10,000, more preferably 1500 to 8000, and further preferably 2000 to 5000. The average degree of polymerization of the polyvinyl alcohol resin can also be determined according to JIS K 6726 (1994). If the average degree of polymerization is less than 100, it is difficult to obtain preferable polarizing performance, and if it exceeds 10,000, the solubility in a solvent is deteriorated, and the formation of a polyvinyl alcohol-based resin film becomes difficult.

  The dichroic dye contained (adsorption orientation) in the polarizing film 5 can be iodine or a dichroic organic dye. Specific examples of the dichroic organic dye include: Red BR, Red LR, Red R, Pink LB, Rubin BL, Bordeaux GS, Sky Blue LG, Lemon Yellow, Blue BR, Blue 2R, Navy RY, Green LG, Violet LB, Violet B, Black H, Black B, Black GSP, Yellow 3G, Yellow R, Orange LR, Orange 3R, Scarlet GL, Scarlet KGL, Congo Red, Brilliant Violet BK, Spura Blue G, Spura Blue GL, Spura Orange GL, Direct Includes Sky Blue, Direct First Orange S and First Black. A dichroic dye may be used individually by 1 type, and may use 2 or more types together.

  The polarizing film 5 is a step of uniaxially stretching a polyvinyl alcohol resin film; a step of adsorbing a dichroic dye by dyeing the polyvinyl alcohol resin film with a dichroic dye; a polyvinyl on which the dichroic dye is adsorbed It can be manufactured through a step of treating an alcohol-based resin film with a boric acid aqueous solution; and a step of washing with water after the treatment with the boric acid aqueous solution.

  The polyvinyl alcohol-based resin film is obtained by forming the above-described polyvinyl alcohol-based resin into a film. The film forming method is not particularly limited, and a known method such as a melt extrusion method or a solvent casting method can be employed. The thickness of the polyvinyl alcohol-based resin film is, for example, about 10 to 150 μm.

  Uniaxial stretching of the polyvinyl alcohol-based resin film can be performed before, simultaneously with, or after dyeing the dichroic dye. When uniaxial stretching is performed after dyeing, this uniaxial stretching may be performed before boric acid treatment or during boric acid treatment. Moreover, you may uniaxially stretch in these several steps.

  In uniaxial stretching, it may be uniaxially stretched between rolls having different peripheral speeds, or may be uniaxially stretched using a hot roll. Further, the uniaxial stretching may be dry stretching in which stretching is performed in the air, or may be wet stretching in which stretching is performed in a state where a solvent is used and the polyvinyl alcohol-based resin film is swollen. The draw ratio is usually about 3 to 8 times.

  As a method of dyeing the polyvinyl alcohol resin film with the dichroic dye, for example, a method of immersing the polyvinyl alcohol resin film in an aqueous solution (dye solution) containing the dichroic dye is employed. The polyvinyl alcohol-based resin film is preferably subjected to an immersion treatment (swelling treatment) in water before the dyeing treatment.

  When iodine is used as the dichroic dye, a method of dyeing a polyvinyl alcohol-based resin film in an aqueous solution containing iodine and potassium iodide is usually employed. The content of iodine in this dyeing aqueous solution is usually about 0.01 to 1 part by weight per 100 parts by weight of water. The content of potassium iodide is usually about 0.5 to 20 parts by weight per 100 parts by weight of water. The temperature of the dyeing aqueous solution is usually about 20 to 40 ° C. Moreover, the immersion time (dyeing time) in the dyeing aqueous solution is usually about 20 to 1800 seconds.

On the other hand, when a dichroic organic dye is used as the dichroic dye, a method of dyeing a polyvinyl alcohol resin film by immersing it in a dyeing aqueous solution containing a water-soluble dichroic organic dye is usually employed. The content of the dichroic organic dye in the dyeing aqueous solution is usually about 1 × 10 ⁻⁴ to 10 parts by weight per 100 parts by weight of water, and preferably about 1 × 10 ⁻³ to 1 part by weight. This dyeing aqueous solution may contain an inorganic salt such as sodium sulfate as a dyeing aid. The temperature of the dyeing aqueous solution is usually about 20 to 80 ° C. Moreover, the immersion time (dyeing time) in the dyeing aqueous solution is usually about 10 to 1800 seconds.

  The boric acid treatment after dyeing with a dichroic dye can be performed by immersing the dyed polyvinyl alcohol-based resin film in a boric acid-containing aqueous solution.

  The amount of boric acid in the boric acid-containing aqueous solution is usually about 2 to 15 parts by weight and preferably 5 to 12 parts by weight per 100 parts by weight of water. When iodine is used as the dichroic dye, the boric acid-containing aqueous solution preferably contains potassium iodide. The amount of potassium iodide in the boric acid-containing aqueous solution is usually about 0.1 to 15 parts by weight and preferably about 5 to 12 parts by weight per 100 parts by weight of water. The immersion time in the boric acid-containing aqueous solution is usually about 60 to 1200 seconds, preferably about 150 to 600 seconds, and more preferably about 200 to 400 seconds. The temperature of the boric acid-containing aqueous solution is usually 50 ° C or higher, preferably 50 to 85 ° C, and more preferably 60 to 80 ° C.

  The polyvinyl alcohol resin film after the boric acid treatment is usually washed with water. The water washing treatment can be performed, for example, by immersing a boric acid-treated polyvinyl alcohol resin film in water. The temperature of water in the water washing treatment is usually about 1 to 40 ° C. Further, the immersion time is usually about 1 to 120 seconds.

  After washing with water, a drying process is performed to obtain the polarizing film 5. There are various drying methods, such as a method of blowing hot air, a method of contacting with a hot roll, and a method of heating with an IR heater, all of which can be suitably used. The method of drying by contacting with a heat roll is preferable in that the drying time can be shortened because the drying efficiency is improved, and the film can be widened by suppressing shrinkage in the width direction of the film. is there. The drying temperature in the drying process means the atmospheric temperature in the drying furnace in the case of a drying facility provided with a drying furnace such as a method of blowing hot air or an IR heater, and is a contact type drying such as a hot roll. In the case of equipment, it means the surface temperature of the hot roll.

  The temperature of the drying treatment is usually about 30 to 100 ° C, preferably 50 to 80 ° C. The time for the drying treatment is usually about 60 to 600 seconds, and preferably 120 to 600 seconds. The thickness of the polarizing film 5 is usually about 2 to 40 μm.

  By the drying process, the moisture content of the polarizing film 5 is reduced to a practical level. The moisture content is usually adjusted to 5 to 45% by weight, more preferably 8 to 40% by weight. When it is lower than 5% by weight, the flexibility of the polarizing film 5 is lost, and the polarizing film 5 may be damaged or broken after drying. When it is higher than 45% by weight, the adhesion with the protective film Becomes difficult to express sufficiently, and problems such as poor appearance and film breakage in the line and contamination of the process are likely to occur.

[First protective film]
The first protective film 20 is a thermoplastic resin, for example, a polyolefin resin such as a chain polyolefin resin (polypropylene resin, etc.), a cyclic polyolefin resin (norbornene resin, etc.); cellulose triacetate, cellulose diacetate, etc. Cellulose ester resins; polyester resins such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate; polycarbonate resins; (meth) acrylic resins such as polymethyl methacrylate resins; or a mixture or copolymer thereof It can be a transparent resin film made of a material or the like.

  Examples of the chain polyolefin-based resin include a homopolymer of a chain olefin such as a polyethylene resin and a polypropylene resin, and a copolymer composed of two or more chain olefins. More specific examples include polypropylene resins (polypropylene resins that are homopolymers of propylene and copolymers mainly composed of propylene), polyethylene resins (polyethylene resins that are homopolymers of ethylene and ethylene mainly) A copolymer).

  The cyclic polyolefin resin is a general term for resins that are polymerized using a cyclic olefin as a polymerization unit, and is described in, for example, JP-A-1-240517, JP-A-3-14882, JP-A-3-122137, and the like. Resin. Specific examples of cyclic polyolefin resins include ring-opening (co) polymers of cyclic olefins, addition polymers of cyclic olefins, copolymers of cyclic olefins and chain olefins such as ethylene and propylene (typically Are random copolymers), graft polymers obtained by modifying them with unsaturated carboxylic acids or derivatives thereof, and hydrides thereof. Among these, norbornene resins using norbornene monomers such as norbornene and polycyclic norbornene monomers as cyclic olefins are preferably used.

  The cellulose ester resin is an ester of cellulose and a fatty acid. Specific examples of the cellulose ester resin include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. Moreover, these copolymers and those in which a part of the hydroxyl group is modified with other substituents can also be used. Among these, cellulose triacetate (triacetyl cellulose: TAC) is particularly preferable.

  The polyester-based resin is a resin having an ester bond, and is generally made of a polycondensate of a polyvalent carboxylic acid or a derivative thereof and a polyhydric alcohol. As the polyvalent carboxylic acid or a derivative thereof, a divalent dicarboxylic acid or a derivative thereof can be used, and examples thereof include terephthalic acid, isophthalic acid, dimethyl terephthalate, and dimethyl naphthalenedicarboxylate. As the polyhydric alcohol, a divalent diol can be used, and examples thereof include ethylene glycol, propanediol, butanediol, neopentyl glycol, and cyclohexanedimethanol. Examples of suitable polyester-based resins include polyethylene terephthalate.

  The polycarbonate-based resin is an engineering plastic made of a polymer in which monomer units are bonded via a carbonate group, and is a resin having high impact resistance, heat resistance, flame retardancy, and transparency. The polycarbonate-based resin may be a resin called a modified polycarbonate in which the polymer skeleton is modified in order to lower the photoelastic coefficient, a copolymerized polycarbonate with improved wavelength dependency, or the like.

The (meth) acrylic resin is a resin containing a compound having a (meth) acryloyl group as a main constituent monomer. Specific examples of (meth) acrylic resins include, for example, poly (meth) acrylic acid esters such as polymethyl methacrylate; methyl methacrylate- (meth) acrylic acid copolymer; methyl methacrylate- (meth) acrylic acid Ester copolymer; methyl methacrylate-acrylic ester- (meth) acrylic acid copolymer; (meth) methyl acrylate-styrene copolymer (MS resin etc.); methyl methacrylate and alicyclic hydrocarbon group And a copolymer (for example, methyl methacrylate-cyclohexyl methacrylate copolymer, methyl methacrylate- (meth) acrylate norbornyl copolymer). Preferably, a polymer based on a poly (meth) acrylic acid C _1-6 alkyl ester such as poly (meth) acrylic acid methyl is used, and more preferably methyl methacrylate is the main component (50-100). % Methyl methacrylate resin is used.

  The first protective film 20 can also be a protective film having an optical function such as a retardation film and a brightness enhancement film. For example, a retardation film provided with an arbitrary retardation value by stretching a transparent resin film made of the above material (uniaxial stretching or biaxial stretching) or forming a liquid crystal layer or the like on the film. It can be.

  A surface treatment layer (coating layer) such as a hard coat layer, an antiglare layer, an antireflection layer, an antistatic layer, and an antifouling layer is formed on the surface of the first protective film 20 opposite to the polarizing film 5. You can also. The method for forming the surface treatment layer on the surface of the protective film is not particularly limited, and a known method can be used.

  Although it is preferable that the thickness of the 1st protective film 20 is thin from a viewpoint of thinning of a polarizing plate, when too thin, intensity | strength will fall and it will be inferior to workability. Therefore, it is preferable that the thickness of the 1st protective film 20 is 5-90 micrometers or less, More preferably, it is 5-60 micrometers, More preferably, it is 5-50 micrometers.

The moisture permeability of the first protective film 20 is preferably 400 g / m ² · 24 hr or more, and more preferably 420 g / m ² · 24 hr or more. If the moisture permeability is within this range, the layer made of the water-based adhesive 55 can be efficiently dried in the subsequent second step, so that productivity can be increased.

(Water-based adhesive)
The water-based adhesive 55 that forms the first adhesive layer 25 is obtained by dissolving an adhesive component in water or dispersing it in water. The aqueous adhesive preferably used is, for example, an adhesive composition using a polyvinyl alcohol resin or a urethane resin as a main component. The thickness of the 1st adhesive bond layer 25 formed from a water-system adhesive agent is 1 micrometer or less normally.

  When a polyvinyl alcohol-based resin is used as the main component of the adhesive, the polyvinyl alcohol-based resin may be partially saponified polyvinyl alcohol or fully saponified polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, or methylol group. It may be a modified polyvinyl alcohol resin such as modified polyvinyl alcohol or amino group-modified polyvinyl alcohol. Polyvinyl alcohol resins include vinyl alcohol homopolymers obtained by saponifying polyvinyl acetate, which is a homopolymer of vinyl acetate, as well as copolymerization of vinyl acetate and other monomers copolymerizable therewith. It may be a polyvinyl alcohol copolymer obtained by saponifying the coalescence.

  A water-based adhesive having a polyvinyl alcohol resin as an adhesive component is usually an aqueous solution of a polyvinyl alcohol resin. The density | concentration of the polyvinyl alcohol-type resin in an adhesive agent is 1-10 weight part normally with respect to 100 weight part of water, Preferably it is 1-5 weight part.

  Adhesives composed of aqueous solutions of polyvinyl alcohol resins include curable components and crosslinking agents such as polyhydric aldehydes, melamine compounds, zirconia compounds, zinc compounds, glyoxal, and water-soluble epoxy resins in order to improve adhesion. Is preferably added. Examples of water-soluble epoxy resins include polyamide polyamine epoxy resins obtained by reacting polychloroalkylenes such as diethylenetriamine and triethylenetetramine with polycarboxylic acid polyamines such as adipic acid and epichlorohydrin. Can be suitably used. Commercially available products of such polyamide polyamine epoxy resins include “Smiles Resin 650” (Taoka Chemical Industry Co., Ltd.), “Smiles Resin 675” (Taoka Chemical Industry Co., Ltd.), “WS-525” (Japan). PMC Co., Ltd.). The addition amount of these curable components and crosslinking agents (when added together as the curable component and the crosslinking agent) is usually 1 to 100 parts by weight, preferably 100 parts by weight, preferably 100 parts by weight of the polyvinyl alcohol resin. 1 to 50 parts by weight. When the addition amount of the curable component or the crosslinking agent is less than 1 part by weight with respect to 100 parts by weight of the polyvinyl alcohol-based resin, the effect of improving adhesiveness tends to be reduced. When the addition amount of the crosslinking agent exceeds 100 parts by weight with respect to 100 parts by weight of the polyvinyl alcohol resin, the adhesive layer tends to become brittle.

  When a urethane resin is used as the main component of the adhesive, examples of a suitable adhesive composition include a mixture of a polyester ionomer type urethane resin and a compound having a glycidyloxy group. The polyester ionomer type urethane resin is a urethane resin having a polyester skeleton, into which a small amount of an ionic component (hydrophilic component) is introduced. Such an ionomer-type urethane resin is suitable as a water-based adhesive because it is emulsified directly in water without using an emulsifier to form an emulsion.

[Peeling film]
The release film 10 is a film that can be peeled off at a desired timing after being laminated on the polarizing film 5. “Peelable” means that the polarizing film 5 and the peeling film 10 can be separated without damaging or damaging the polarizing film 5 and the peeling film 10.

  The release film 10 is, for example, a chain polyolefin resin such as a polyethylene resin or a polypropylene resin; a cellulose ester resin such as a cellulose triacetate or a cellulose diacetate; It can be a transparent resin film made of a polyester resin such as terephthalate, polyethylene naphthalate or polybutylene terephthalate; a (meth) acrylic resin such as polymethyl methacrylate resin, or a mixture or copolymer thereof. . A film in which one or more of these are formed into a single layer or a multilayer can be used as the release film 10. Among these, a film made of polyethylene terephthalate, cellulose triacetate, or polymethyl methacrylate resin can be suitably used.

  The peeling force between the polarizing film 5 and the peeling film 10 is, for example, 0.01 to 0.5 N / 25 mm, preferably 0.01 to 0.2 N / 25 mm, more preferably 0.01 to 0.15 N. / 25 mm. When the peeling force is less than 0.01 N / 25 mm, the adhesive force between the polarizing film 5 and the peeling film 10 is small, so that the peeling film 10 is partially peeled off or the single-sided protective polarizing plate is rolled. During storage, the polarizing film 5 may tear along the stretching direction (in a direction parallel to the stretching direction). Moreover, since it will become difficult to peel the peeling film 10 from the polarizing film 5 when peeling force exceeds 0.5 N / 25mm, when peeling the peeling film 10, the polarizing film 5 is easy to tear along an extending | stretching direction. Sometimes.

  Here, the peeling force is obtained by cutting a single-side protective polarizing plate on which the release film 10 is laminated to a width of 25 mm to obtain a measurement sample, and precision universal testing machine “Autograph AGS-50NX” manufactured by Shimadzu Corporation. Is used to grasp the peeling film 10 of the measurement sample and the single-sided protective polarizing plate and measure the force when peeling in the 180 ° direction. The peeling force is measured in an environment where the peeling speed is 300 mm / min, the temperature is 23 ± 2 ° C., and the relative humidity is 50 ± 5%.

  The thickness of the release film 10 is, for example, about 5 to 100 μm, and preferably about 10 to 80 μm.

The moisture permeability of the release film 10 is preferably 400 g / m ² · 24 hr or more, and more preferably 420 g / m ² · 24 hr or more. When the moisture permeability is within this range, the layer made of the volatile liquid 50 can be efficiently volatilized and removed in the subsequent second step, so that productivity can be improved.

  The release film 10 preferably has a shrinkage rate (heat shrinkage rate) of 0.15% or less, more preferably 0.1% or less when heated at 80 ° C. for 5 minutes. When the heat shrinkage rate of the release film 10 is large, the release film 10 is likely to be wrinkled in the heat treatment in the second step, and accordingly, the single-sided protective polarizing plate is likely to be wrinkled. Examples of the resin material having a heat shrinkage within the above range include polyethylene terephthalate, cellulose triacetate, and polymethyl methacrylate resin.

  Note that “the heat shrinkage is 0.15% or less” means that both the MD shrinkage and the TD shrinkage are 0.15% or less.

  The contact angle with respect to the volatile liquid 50 on the surface of the polarizing film 5 in the release film 10 is 50 to 80 °, preferably 50 to 75 °, and the peeling force between the polarizing film 5 and the release film 10 is in the above range. It is advantageous in that the release film 10 can be peeled relatively easily. For the same reason, the contact angle with respect to the volatile liquid 50 on the surface of the release film 10 in the polarizing film 5 is preferably 50 to 110 °, and more preferably 50 to 100 °.

[Volatile liquid]
The volatile liquid 50 interposed between the polarizing film 5 and the release film 10 is a liquid that can be volatilized by the heat treatment in the second step, and is preferably a liquid that does not adversely affect the polarizing film 5. An antistatic agent may be added as long as it does not have an adverse effect. Examples of the volatile liquid 50 that can be used in the present invention include water and a mixture of water and a hydrophilic liquid. The hydrophilic liquid is preferably one that does not remain after the heat treatment in the second step. For example, methanol, ethanol, 1-butanol, tetrohydrofuran, acetone, acetonitrile, N, N-dimethylformamide, dimethyl sulfoxide, Examples include formic acid and acetic acid.

(2) 2nd process This process is a process of volatilizing and removing the volatile liquid 50 while drying the 1st adhesive bond layer 25 which is a water-system adhesive bond layer by heating. By this heat treatment, the release film 10 is directly laminated on the surface of the polarizing film 5 with an appropriate adhesion.

  With reference to FIG. 5, the said heat processing are performed by introduce | transducing into the drying apparatus 70 the laminated | multilayer film which consists of the 1st protective film 20, the polarizing film 5, and the peeling film 10 which passed between the bonding rolls 40 and 40. FIG. be able to. Thereby, the single-sided protective polarizing plate 2 with a peeling film is obtained. The drying device 70 is not particularly limited, and a hot air dryer or a far infrared heater can be used.

  The drying temperature is preferably 30 to 90 ° C. In the obtained single-sided protective polarizing plate 2 with a release film, when it is lower than 30 ° C., the first protective film 20 tends to be easily peeled off from the polarizing film 5. If the drying temperature exceeds 90 ° C., the polarizing performance of the polarizing film 5 may be deteriorated by heat. The drying time can be about 10 to 1000 seconds, and from the viewpoint of productivity, it is preferably 60 to 750 seconds, and more preferably 150 to 600 seconds.

  One of the advantages of the present invention is that the heating temperature in this step can be increased to, for example, more than 60 ° C. and 90 ° C. That is, even if the heating temperature is set high, in addition to being able to suppress the breakage of the polarizing film 5, it is possible to obtain a single-sided protective film with a small shrinkage rate of the polarizing film 5 and thus high dimensional stability by the high temperature heating. it can. By reducing the shrinkage rate of the single-side protective polarizing plate, the warpage of the liquid crystal panel can be reduced when a liquid crystal panel is produced using the polarizing plate. Conventionally, since the polarizing film is easily broken, the drying temperature of the aqueous adhesive layer cannot be set high, and it has been difficult to obtain a single-side protective polarizing plate having a low shrinkage rate.

(3) Other Steps After the second step, sufficient adhesive strength may be obtained by performing curing at a temperature of room temperature or higher for at least half a day, usually several days or longer. Such curing is typically performed in a state of being wound into a roll. The preferable curing temperature is in the range of 30 to 50 ° C, more preferably 35 to 45 ° C. When the curing temperature exceeds 50 ° C., so-called “roll tightening” is likely to occur in the roll winding state. The humidity during curing is not particularly limited, but is preferably selected so that the relative humidity is in the range of about 0 to 70% RH. The curing time is usually about 1 to 10 days, preferably about 2 to 7 days.

  After the second step, the third step of peeling and removing the release film 10 from the single-side protective polarizing plate 2 with the release film, and the step of laminating the pressure-sensitive adhesive layer 30 on the surface of the polarizing film 5 on which the release film 10 was laminated. Four steps can be provided to form the single-sided protective polarizing plate 3 with the pressure-sensitive adhesive layer shown in FIG. This pressure-sensitive adhesive layer 30 can be used for bonding a single-sided protective polarizing plate to a liquid crystal cell.

  As the pressure-sensitive adhesive used for the pressure-sensitive adhesive layer 30, a conventionally known appropriate pressure-sensitive adhesive can be used. For example, (meth) acrylic pressure-sensitive adhesive, urethane-based pressure-sensitive adhesive, silicone-based pressure-sensitive adhesive, polyester-based pressure-sensitive adhesive, polyamide Based adhesives, polyether based adhesives, fluorine based adhesives, rubber based adhesives, and the like. Of these, a (meth) acrylic pressure-sensitive adhesive is preferably used from the viewpoints of transparency, adhesive strength, reliability, reworkability, and the like. The pressure-sensitive adhesive layer 30 can be provided by a method in which a pressure-sensitive adhesive is used, for example, in the form of an organic solvent solution, which is coated on the polarizing film 5 with a die coater or a gravure coater and dried. Can be provided also by a method of transferring the sheet-like adhesive formed on the plastic film (referred to as a separate film) to the polarizing film 5. Whichever method is used, it is preferable that a separate film is adhered to the surface of the pressure-sensitive adhesive layer 30. The thickness of the pressure-sensitive adhesive layer 30 can be 2 to 40 μm, for example.

  Alternatively, instead of providing the fourth step, a double-sided protective polarizing plate is obtained by laminating the second protective film 21 via the second adhesive layer 26 on the surface of the polarizing film 5 on which the release film 10 is laminated. 4 can also be obtained. Similar to the first adhesive layer 25, the second adhesive layer 26 may be a water-based adhesive layer, or may be a layer made of another adhesive. Examples of other adhesives include active energy ray-curable adhesives that can be cured by irradiation with active energy rays such as ultraviolet rays, visible light, electron beams, and X-rays. In this case, the second adhesive layer 26 is a cured product layer of the adhesive.

  The second protective film 21 can also be a protective film having an optical function such as a retardation film and a brightness enhancement film. The double-sided protective polarizing plate 4 can be bonded to the liquid crystal cell using the adhesive layer 30 laminated on the outer surface of the first protective film 20 or the second protective film 21.

  Among them, as the adhesive for forming the second adhesive layer 26, an active energy ray-curable adhesive having an epoxy compound that is cured by cationic polymerization as a curable component can be more preferably used, and such an epoxy is more preferable. It is an ultraviolet curable adhesive having a curable compound as a curable component. The epoxy compound here means a compound having an average of 1 or more, preferably 2 or more epoxy groups in the molecule. Epoxy compounds may be used alone or in combination of two or more.

  An example of an epoxy compound that can be suitably used is a hydrogenated epoxy compound (aliphatic compound) obtained by reacting an alicyclic polyol obtained by hydrogenating an aromatic ring of an aromatic polyol with epichlorohydrin. A glycidyl ether of a polyol having a cyclic ring); an aliphatic epoxy compound such as an aliphatic polyhydric alcohol or a polyglycidyl ether of an alkylene oxide adduct thereof; one epoxy group bonded to the alicyclic ring in the molecule An alicyclic epoxy compound which is an epoxy compound having the above is included.

  The active energy ray-curable adhesive may further contain a (meth) acrylic compound that is radically polymerizable as a curable component. The (meth) acrylic compound is a (meth) acrylate monomer having at least one (meth) acryloyloxy group in the molecule; obtained by reacting two or more functional group-containing compounds, and at least two in the molecule. And (meth) acryloyloxy group-containing compounds such as (meth) acrylate oligomers having (meth) acryloyloxy groups.

  When the active energy ray-curable adhesive contains an epoxy compound that is cured by cationic polymerization as a curable component, it preferably contains a photocationic polymerization initiator. Examples of the photocationic polymerization initiator include aromatic diazonium salts; onium salts such as aromatic iodonium salts and aromatic sulfonium salts; iron-allene complexes. Moreover, when the active energy ray-curable adhesive contains a radical polymerizable curable component such as a (meth) acrylic compound, it is preferable to contain a photo radical polymerization initiator. Examples of the photo radical polymerization initiator include acetophenone initiator, benzophenone initiator, benzoin ether initiator, thioxanthone initiator, xanthone, fluorenone, camphorquinone, benzaldehyde, anthraquinone and the like.

  When using an active energy ray-curable adhesive, a curing step for curing the adhesive layer made of this is performed. Curing of the adhesive layer can be performed by irradiating active energy rays. The active energy ray is preferably ultraviolet rays.

  The light source of the active energy ray is not particularly limited, but an active energy ray having a light emission distribution at a wavelength of 400 nm or less is preferable. Specifically, the low-pressure mercury lamp, the medium-pressure mercury lamp, the high-pressure mercury lamp, the ultrahigh-pressure mercury lamp, the chemical lamp, and the black light lamp A microwave excited mercury lamp, a metal halide lamp, or the like is preferably used.

The active energy ray irradiation intensity to the adhesive layer composed of the active energy ray-curable adhesive is appropriately determined depending on the composition of the adhesive, but the irradiation intensity in the wavelength region effective for activating the polymerization initiator is 0.1. It is preferably set to be ˜6000 mW / cm ² . When the irradiation intensity is 0.1 mW / cm ² or more, the reaction time does not become too long, and when it is 6000 mW / cm ² or less, the heat of the adhesive layer due to the heat radiated from the light source and the heat generated when the adhesive is cured. There is little possibility of causing yellowing or deterioration of the polarizing film 5.

The irradiation time of the active energy ray is also appropriately determined depending on the composition of the adhesive, but is set so that the integrated light amount expressed as the product of the irradiation intensity and the irradiation time is 10 to 10,000 mJ / cm ^2. Is preferred. When the integrated light amount is 10 mJ / cm ² or more, a sufficient amount of active species derived from the polymerization initiator can be generated to advance the curing reaction more reliably, and when it is 10000 mJ / cm ² or less, the irradiation time is long. It does not become too much, and good productivity can be maintained.

  Regarding the material and configuration of the second protective film 21, the contents described for the first protective film 20 are cited. The first protective film 20 and the second protective film 21 may be the same type of film or different types of films.

  EXAMPLES Hereinafter, although an Example is shown and this invention is demonstrated further more concretely, this invention is not limited by these examples. The moisture permeability, shrinkage rate, contact angle, and peel force in the following examples were measured according to the following methods.

(1) Moisture permeability of protective film and release film The moisture permeability (g / m ² · 24 hr) at 40 ° C. was measured according to JIS Z 0208.

(2) Shrinkage rate of release film A square test piece having a side of 100 mm was cut out from the release film so that one side was parallel to the MD (film longitudinal direction) of the release film, and the initial dimension A (MD From the initial dimension) and the dimension B (MD dimension) after holding the test piece in a dry heat environment at 80 ° C. for 5 minutes:
MD dimensional change rate (%) = (A−B) / A × 100
Thus, the MD dimensional change rate of the release film was calculated, and this was taken as the MD shrinkage rate. Similarly, from the initial dimension A ′ (the initial dimension of TD) and the dimension B ′ (the dimension of TD) after holding the test piece in a dry heat environment at 80 ° C. for 5 minutes, the TD dimensional change rate is calculated. This was calculated and used as the TD shrinkage rate.

(3) The surface to be measured for the contact angle of the polarizing film and the release film surface (the release film side surface in the polarization film or the polarization film side surface in the release film) is the outside, and the polarizing film or release film is used on a glass substrate with an adhesive. To obtain a measurement sample. This measurement sample is set horizontally on a contact angle meter (image processing contact angle meter “FACE CA-X type” manufactured by Kyowa Interface Science Co., Ltd.) so that the surface to be measured is the upper surface, and 1 A microliter of volatile liquid was dropped, and the contact angle with respect to the volatile liquid was measured.

(4) Peeling force between polarizing film and release film Peeling force is obtained by cutting a single-side protective polarizing plate on which a release film is laminated to a width of 25 mm to obtain a measurement sample, and precision universal made by Shimadzu Corporation Using a tester “Autograph AGS-50NX”, the peeling film of the measurement sample and the single-sided protective polarizing plate were gripped and measured by measuring the force when peeling in a 180 ° direction. The peeling force was measured in an environment with a peeling speed of 300 mm / min, a temperature of 23 ± 2 ° C., and a relative humidity of 50 ± 5%.

<Example 1>
(A) Production of Polarizing Film A polyvinyl alcohol film having an average degree of polymerization of about 2400 and a saponification degree of 99.9 mol% or more and a thickness of 30 μm was uniaxially stretched about 4 times in a dry manner, and further kept in a tension state. After immersing in pure water of 1 ° C. for 1 minute, it was immersed in an aqueous solution having a weight ratio of iodine / potassium iodide / water of 0.1 / 5/100 at 28 ° C. for 60 seconds. Thereafter, it was immersed in an aqueous solution having a weight ratio of potassium iodide / boric acid / water of 10.5 / 7.5 / 100 at 68 ° C. for 300 seconds. Subsequently, it was washed with pure water at 5 ° C. for 5 seconds and then dried at 70 ° C. for 180 seconds to obtain a polarizing film in which iodine was adsorbed and oriented on a uniaxially stretched polyvinyl alcohol film. The thickness of the polarizing film was 11 μm.

(B) Preparation of water-based adhesive Polyvinyl alcohol powder [trade name “KL-318” manufactured by Kuraray Co., Ltd., average polymerization degree 1800] was dissolved in 95 ° C. hot water, and an aqueous polyvinyl alcohol solution having a concentration of 3% by weight was dissolved. Prepared. The resulting aqueous solution was mixed with a crosslinking agent [trade name “Smiles Resin 650” manufactured by Taoka Chemical Industry Co., Ltd.] at a ratio of 1 part by weight to 2 parts by weight of polyvinyl alcohol powder to obtain an aqueous adhesive. .

(C) Production of single-sided protective polarizing plate with release film A single-sided protective polarizing plate with a release film was produced by the following procedure using the same apparatus as the polarizing plate production apparatus shown in FIG. While continuously transporting the polarizing film obtained in (A) above, a protective film [trade name “KC2UAW”, which is a TAC film manufactured by Konica Minolta Opto Co., Ltd., thickness 25 μm, saponification treatment on the bonding surface The protective film is continuously unwound from the roll of the applied one, and from the roll of the release film [trade name “KC8UX2MW”, thickness 80 μm, no saponification treatment, manufactured by Konica Minolta Opto, Inc.] The release film was continuously unwound. Next, the aqueous adhesive obtained in (B) above is injected between the polarizing film and the protective film, and pure water is injected between the polarizing film and the release film, and between the bonding rolls 40 and 40. A laminated film consisting of a protective film / aqueous adhesive layer / polarizing film / pure water / release film was formed (first step). Subsequently, the laminated film is transported and passed through a drying device 70 and heated at 80 ° C. for 300 seconds, so that the water-based adhesive layer is dried and the pure water interposed between the polarizing film and the release film is volatilized and removed. And the single-sided protective polarizing plate with a peeling film was obtained (2nd process).

  During the production of the single-side protective polarizing plate with a release film, the polarizing film was not broken and the polarizing plate was not wrinkled. Table 1 shows the measurement results of the moisture permeability, shrinkage rate, and water contact angle of the polarizing film, protective film or release film used. In addition, Table 1 summarizes the breakage of the polarizing film and the occurrence of wrinkling of the polarizing plate during the production of the single-side protective polarizing plate with a release film.

  It was 0.10 N / 25mm when the peeling force between a polarizing film and a peeling film was measured about the obtained single-sided protective polarizing plate with a peeling film according to the above-mentioned measuring method.

<Examples 2-11, Comparative Examples 1-2>
A single-side protective polarizing plate with a release film was produced in the same manner as in Example 1 except that the type of the protective film and the type of the release film were as shown in Table 1. In Comparative Examples 1 and 2, the release film was directly laminated on the surface of the polarizing film without interposing pure water between the polarizing film and the release film in the first step.

  As in Example 1, measurement of moisture permeability, shrinkage rate, water contact angle of polarizing film, protective film or release film used, and breakage of polarizing film during production of single-side protective polarizing plate with release film, polarizing plate Table 1 also summarizes the occurrence of wrinkles. Details of the abbreviations in Table 1 are as follows.

[A] TAC1: a product name "KC2UAW" which is a TAC film manufactured by Konica Minolta Opto Co., Ltd., a thickness of 25 μm, and a saponification treatment is performed on the bonding surface;
[B] COP: trade name “FEKB015D3” which is a cyclic polyolefin resin film manufactured by JSR Corporation, thickness 15 μm,
[C] PET: Mitsubishi terephthalate polyethylene terephthalate film, thickness 25 μm,
[D] Acrylic 1: polymethyl methacrylate resin film of Sumitomo Chemical Co., Ltd., thickness 40 μm,
[E] TAC2: trade name “KC8UX2MW”, a TAC film manufactured by Konica Minolta Opto Co., Ltd., thickness 80 μm, no saponification treatment,
[F] PE: trade name “Tretec 7332K” which is a polyethylene film of Toray Film Processing Co., Ltd.
[G] Acrylic 2: polymethyl methacrylate resin film of Sumitomo Chemical Co., Ltd., thickness 80 μm,
[H] EtOH: ethanol.

  As shown in Table 1, in Examples 1 to 11, since a volatile liquid was interposed between the polarizing film and the release film, the polarizing film was not broken even when heat treatment was performed at 80 ° C. . On the other hand, in Comparative Examples 1 and 2 in which no volatile liquid was interposed, the polarizing film was broken by the heat treatment at 80 ° C. In Examples 9 and 10 in which a volatile liquid was interposed between the polarizing film and the release film and the release film having a large shrinkage was used, wrinkles were generated on the polarizing plate by the heat treatment at 80 ° C.

  1 single-sided protective polarizing plate, 2 single-sided protective polarizing plate with release film, 3 single-sided protective polarizing plate with adhesive layer, 4 double-sided protective polarizing plate, 5 polarizing film, 10 release film, 20 first protective film, 21 second protective film , 25 1st adhesive layer, 26 2nd adhesive layer, 30 adhesive layer, 40 pasting roll, 50 volatile liquid, 55 aqueous adhesive, 60 guide roll, 70 drying device, 80, 81 injection device.

Claims (5)

With laminating one surface to via the aqueous adhesive layer of the protective film of the polarizing film, the other surface of the polarizing film, a first step of laminating a release film through a volatile liquid body,
A second step of drying the aqueous adhesive layer by heating and volatilizing the volatile liquid;
The manufacturing method of a polarizing plate containing. The method for producing a polarizing plate according to claim 1, wherein at least one of the protective film and the release film has a moisture permeability of 400 g / m ² · 24 hr or more.   The said peeling film is a manufacturing method of the polarizing plate of Claim 1 or 2 whose shrinkage rate when heated at 80 degreeC for 5 minute (s) is 0.15% or less.   The manufacturing method of the polarizing plate of any one of Claims 1-3 whose contact angle with respect to the said volatile liquid of the polarizing film side surface in the said peeling film is 50-80 degrees.   The manufacturing method of the polarizing plate of any one of Claims 1-4 whose contact angle with respect to the said volatile liquid of the peeling film side surface in the said polarizing film is 50-110 degrees.

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