WO2017104463A1 - Method for manufacturing one-side-protected polarizing plate - Google Patents

Abstract

[Problem] To provide a high-yield method for manufacturing a one-side-protected polarizing plate whereby a polarizing film and a release film can easily be peeled. [Solution] A method for manufacturing a one-side-protected polarizing plate, the method including a first step for obtaining a layered body by affixing a protective film to one surface of a polarizing film via an adhesive layer and layering a release film on the other surface of the polarizing film via a layer comprising a volatile liquid, a second step for volatilizing the volatile liquid, and a third step for peeling the release film in a state in which the conveyance direction of the release film to the rear of the peeling point is substantially horizontal with respect to the conveyance direction of the layered body. [Selected drawing] FIG. 1

Description

Manufacturing method of single-sided protective polarizing plate

The present invention relates to a method for producing a single-side protective polarizing plate.

In recent years, with the increase in the size of LCD mobile terminals represented by smartphones, attempts to increase the efficiency of backlight use by methods such as using a brightness enhancement film have been made in order to achieve long-term driving with a limited battery capacity. is there. On the other hand, the demand for thinner LCD mobile terminals is increasing from the viewpoint of design and portability, and in order to make the battery occupying a limited housing as large as possible, the polarizing plates used there are further Thin and light weight is required.

In such a demand, a polarizing plate (for example, JP 2009-109860 A (Patent Document 1)) in which a protective film is laminated only on one side of a polarizing film has been proposed. The polarizing plate disclosed in Patent Document 1 is an effective means for reducing the thickness of the polarizing plate, but when the polarizing film and the protective film are bonded together while the thickness of the polarizing film and the protective film is reduced. Sufficient pressure could not be applied, and the resulting polarizing plate sometimes had poor appearance.

As a countermeasure against such an appearance defect, there is a technique of increasing the overall thickness by arranging a release film on the surface opposite to the protective film in the polarizing film when bonding the polarizing film and the protective film. (Patent Document 2).

This method has the advantage that a variety of release films can be selected. In particular, if the protective film is a cellulose resin film, a (meth) acrylic resin film is preferably used as the release film. If the protective film is a polyolefin resin film, a cellulose resin film is preferably used as the release film.

JP 2009-109860 A International Publication No. 2015/137250

However, volatile liquids such as pure water are preferably used in order to increase the adhesion between the polarizing film and the release film, but the adhesion between the polarizing film and the release film increases with time, and the distance between the polarizing film and the release film increases. It may be difficult to peel off. The objective of this invention is providing the manufacturing method of the single-sided protective polarizing plate which can peel easily a polarizing film and a peeling film, and has high productivity.

[1] A protective film is bonded to one surface of the polarizing film via an adhesive layer, and a release film is laminated to the other surface of the polarizing film via a layer made of a volatile liquid, to obtain a laminate. A first step of obtaining
A second step of volatilizing the volatile liquid;
The manufacturing method of the single-sided protective polarizing plate including the 3rd process of peeling the said peeling film so that the conveyance direction of the said peeling film after a peeling point may become substantially horizontal with respect to the conveyance direction of the said laminated body. .
[2] The method for producing a polarizing plate according to [1], wherein an angle formed by the transport direction of the release film and the transport direction of the laminate after the release point is within 15 °.
[3] Before the step of peeling the release film, the step of winding the laminate having the protective film, the polarizing film and the release film in this order to obtain a roll includes the step of [1] or [2]. Production method.
[4] The method for producing a polarizing plate according to any one of [1] to [3], wherein the volatile liquid contains water.

According to the production method of the present invention, the polarizing film and the release film can be easily peeled off, and a method for producing a single-side protective polarizing plate excellent in productivity can be provided.

It is the schematic which shows an example of the peeling method. It is the schematic which shows an example of the peeling method.

In the present invention, the “single-side protective polarizing plate” is a polarizing plate in which a protective film is bonded only to one side of the polarizing film, and this protective film is usually bonded to the polarizing film via an adhesive layer. The production method of the present invention will be described below.

<Method for producing single-sided protective polarizing plate>
[1] First Step In the first step, a protective film is bonded to one surface of the polarizing film via an adhesive layer, and a layer made of a volatile liquid is interposed on the other surface of the polarizing film. The release film is laminated to obtain a laminate. In general, a polarizing plate such as a single-sided protective polarizing plate can be continuously produced as a long product by performing a treatment in each step while continuously unwinding and transporting a long film. The lamination of the protective film and the polarizing film and the lamination of the release film and the polarizing film may be performed sequentially or simultaneously.

[Polarized film]
The polarizing film is usually a step of uniaxially stretching a polyvinyl alcohol-based resin film, a step of adsorbing a dichroic dye by dyeing the polyvinyl alcohol-based resin film with a dichroic dye, a polyvinyl on which the dichroic dye is adsorbed The alcohol-based resin film is manufactured through a step of crosslinking with a boric acid aqueous solution and a step of washing with water after the crosslinking treatment with the boric acid aqueous solution.

The polyvinyl alcohol resin can be produced by saponifying a polyvinyl acetate resin. The polyvinyl acetate resin may be a copolymer of vinyl acetate and another monomer copolymerizable therewith, in addition to polyvinyl acetate which is a homopolymer of vinyl acetate. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group.

The degree of saponification of the polyvinyl alcohol resin is usually about 85 to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol resin may be modified, for example, polyvinyl formal or polyvinyl acetal modified with aldehydes can be used. The degree of polymerization of the polyvinyl alcohol resin is usually about 1,000 to 10,000, and preferably about 1,500 to 5,000.

A film obtained by forming such a polyvinyl alcohol resin is used as an original film of a polarizing film. The method for forming a polyvinyl alcohol-based resin is not particularly limited, and can be formed by a known method. The film thickness of the polyvinyl alcohol resin raw film is, for example, about 10 to 100 μm, preferably about 10 to 50 μm.

Uniaxial stretching of the polyvinyl alcohol-based resin film can be performed before dyeing with the dichroic dye, simultaneously with dyeing, or after dyeing. When uniaxial stretching is performed after dyeing, the uniaxial stretching may be performed before boric acid treatment or during boric acid treatment. Of course, uniaxial stretching can also be performed in a plurality of stages shown here. For uniaxial stretching, a method of stretching uniaxially between rolls having different peripheral speeds, a method of stretching uniaxially using a hot roll, or the like can be adopted. Uniaxial stretching may be performed by dry stretching in which stretching is performed in the air, or may be performed by wet stretching in which a polyvinyl alcohol-based resin film is stretched using a solvent such as water. The draw ratio is usually about 3 to 8 times.

The dyeing of the polyvinyl alcohol resin film with the dichroic dye can be performed, for example, by a method of immersing the polyvinyl alcohol resin film in an aqueous solution containing the dichroic dye. Specifically, iodine or a dichroic organic dye is used as the dichroic dye. In addition, it is preferable to perform the process which a polyvinyl alcohol-type resin film swells by immersing in water before a dyeing process.

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 iodine content in this aqueous solution is usually about 0.01 to 1 part by weight per 100 parts by weight of water, and the potassium iodide content is usually about 0.5 to 20 parts by weight per 100 parts by weight of water. It is. The temperature of the aqueous solution used for dyeing is usually about 20 to 40 ° C. The immersion time (dyeing time) in this aqueous solution is usually about 20 to 1,800 seconds.

On the other hand, when a dichroic organic dye is used as the dichroic dye, a method of immersing and dyeing a polyvinyl alcohol-based resin film in an aqueous solution containing a water-soluble dichroic organic dye is usually employed. The content of the dichroic organic dye in this aqueous solution is usually about 1 × 10 ⁻⁴ to 10 parts by weight, preferably 1 × 10 ⁻³ to 1 part by weight per 100 parts by weight of water. This aqueous dye solution may contain an inorganic salt such as sodium sulfate as a dyeing assistant. The temperature of the aqueous dichroic organic dye solution used for dyeing is usually about 20 to 80 ° C. The immersion time (dyeing time) in this aqueous solution is usually about 10 to 1,800 seconds.

The boric acid treatment after dyeing with the dichroic dye can be performed by a method of immersing the dyed polyvinyl alcohol-based resin film in a boric acid-containing aqueous solution. The boric acid content in the boric acid-containing aqueous solution is usually about 2 to 15 parts by weight, 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 content of potassium iodide in the boric acid-containing aqueous solution is usually about 0.1 to 15 parts by weight, preferably 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 1,200 seconds, preferably 150 to 600 seconds, and more preferably 200 to 400 seconds. The temperature of the boric acid-containing aqueous solution is usually 50 ° C. or higher, preferably 50 to 85 ° C., 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 a method of immersing a boric acid-treated polyvinyl alcohol resin film in water. The temperature of water in the water washing treatment is usually about 5 to 40 ° C. The immersion time is usually about 1 to 120 seconds.

After washing with water, a drying process is performed to obtain a polarizing film. The drying process can be performed using a hot air dryer or a far infrared heater. The temperature for the drying treatment is usually about 30 to 100 ° C., preferably 50 to 80 ° C. The drying treatment time is usually about 60 to 600 seconds, preferably 120 to 600 seconds. By the drying treatment, the moisture content in the polarizing film is reduced to a practical level. The water content is usually about 5 to 20% by weight, preferably 8 to 15% by weight. When the moisture content is less than 5% by weight, the polarizing film loses its flexibility, and may be damaged or broken after drying. On the other hand, if the moisture content exceeds 20% by weight, the thermal stability tends to be insufficient.

As described above, a polarizing film having a dichroic dye adsorbed and oriented on a polyvinyl alcohol resin film can be produced.

In order to keep the contraction force of the polarizing film in a high temperature environment low, the thickness of the polarizing film is preferably 15 μm or less. The thickness of the polarizing film is usually 3 μm or more in that good optical properties can be imparted.

The polarizing film preferably has a shrinkage force of 2 N or less per 2 mm width in the absorption axis direction when held at a temperature of 80 ° C. for 240 minutes. If the shrinkage force is greater than 2N, the amount of dimensional change under a high temperature environment increases, and the shrinkage force of the polarizing film increases, so that the polarizing film tends to crack. The shrinkage force of the polarizing film tends to be 2N or less when the draw ratio is lowered and the thickness of the polarizing film is reduced.

[Protective film]
The protective film is preferably made of a material having excellent transparency, mechanical strength, thermal stability, moisture shielding properties, retardation value stability, and the like. Such a material for transparent protective film is not particularly limited, but examples thereof include (meth) acrylic resins, polyolefin resins, cyclic olefin resins, polyvinyl chloride resins, cellulose resins, and styrene resins. Resin, acrylonitrile / butadiene / styrene resin, acrylonitrile / styrene resin, polyvinyl acetate resin, polyvinylidene chloride resin, polyamide resin, polyacetal resin, polycarbonate resin, modified polyphenylene ether resin, polybutylene terephthalate And a film made of a polyethylene resin, a polyethylene terephthalate resin, a polysulfone resin, a polyethersulfone resin, a polyarylate resin, a polyamideimide resin, a polyimide resin, or the like. Among these, it is preferable to use a film made of a cellulose resin or a polyolefin resin.

The cellulose resin may be an organic acid ester or mixed organic acid ester of cellulose in which part or all of the hydrogen atoms in the hydroxyl group of cellulose are substituted with an acetyl group, a propionyl group, and / or a butyryl group. Examples include cellulose acetate, propionate, butyrate, and mixed esters thereof. Of these, triacetyl cellulose, diacetyl cellulose, cellulose acetate propionate, cellulose acetate butyrate and the like are preferable.

These resins may contain appropriate additives as long as the transparency is not impaired.
Additives such as antioxidants, ultraviolet absorbers, antistatic agents, lubricants, nucleating agents, antifogging agents, antiblocking agents, phase difference reducing agents, stabilizers, processing aids, plasticizers, impact aids , Matting agents, antibacterial agents, fungicides and the like. A plurality of these additives may be used in combination.

As a method for forming a film from the resin as described above, any optimum method may be appropriately selected. For example, a solvent cast method in which a resin dissolved in a solvent is cast on a metal band or drum, and the solvent is removed by drying to obtain a film. The resin is heated above its melting temperature, kneaded and extruded from a die. A melt extrusion method for obtaining a film by cooling can be used. In the melt extrusion method, a single layer film can be extruded or a multilayer film can be coextruded.

These resin films can be easily obtained as commercial products. Examples of commercially available films include cellulose resin films, each of which is sold under the trade name “Fujitac (registered trademark) TD”, sold by Konica Minolta, Inc. Konica Minolta “TAC” film “KC”.

The olefin resin is a chain aliphatic olefin such as ethylene and propylene, or a structural unit derived from an alicyclic olefin such as norbornene or a substituted product thereof (hereinafter collectively referred to as norbornene monomer). It becomes resin. The olefin resin may be a copolymer using two or more kinds of monomers.

Among these, as the olefin resin, a cyclic olefin resin which is a resin mainly containing a structural unit derived from an alicyclic olefin is preferably used. Typical examples of the alicyclic olefin constituting the cyclic olefin resin include a norbornene monomer. Norbornene is a compound in which one carbon-carbon bond of norbornane is a double bond, and according to IUPAC nomenclature, it is named bicyclo [2,2,1] hept-2-ene. is there. Examples of norbornene substituents include 3-substituted, 4-substituted, 4,5-disubstituted, etc., with norbornene having a double bond position in the 1,2-position. Dicyclopentadiene, dimethanooctahydronaphthalene and the like can also be mentioned.

The cyclic olefin-based resin may or may not have a norbornane ring in its structural unit. Examples of the norbornene-based monomer that forms a cyclic olefin-based resin having no norbornane ring as a structural unit include, for example, those that become a five-membered ring by ring opening, typically norbornene, dicyclopentadiene, 1- or 4- Examples thereof include methyl norbornene and 4-phenyl norbornene. When the cyclic olefin resin is a copolymer, the arrangement state of the molecules is not particularly limited, and may be a random copolymer, a block copolymer, or a graft copolymer. It may be a polymer.

More specific examples of cyclic olefin resins include, for example, ring-opening polymers of norbornene monomers, ring-opening copolymers of norbornene monomers and other monomers, addition of maleic acid and cyclopentadiene, etc. Examples of the polymer-modified products made and hydrogenated polymers or copolymers; addition polymers of norbornene monomers, addition copolymers of norbornene monomers and other monomers, and the like. Examples of other monomers in the case of a copolymer include α-olefins, cycloalkenes, and non-conjugated dienes. Moreover, the cyclic olefin resin may be a copolymer using one or more of norbornene monomers and other alicyclic olefins.

Among the specific examples, as the cyclic olefin-based resin, a ring-opening polymer using a norbornene-based monomer or a resin obtained by hydrogenating a ring-opening copolymer is preferably used.

Such an olefin resin is formed into a film by a casting method or a melt extrusion method from a solution, and is performed by a known longitudinal uniaxial stretching, tenter transverse uniaxial stretching, simultaneous biaxial stretching, sequential biaxial stretching, or the like. A stretched film can be obtained. Cyclic olefin-based resin films using such norbornene-based monomers can be obtained as commercial products. For example, all of them are trade names such as “ZEONOR (registered trademark)” of Nippon Zeon Co., Ltd. and “ Arton (registered trademark) ".

A surface treatment layer (coating layer) such as a hard coat layer, an antiglare layer, an antireflection layer, an antistatic layer, or an antifouling layer can be formed on the surface of the protective film opposite to the polarizing film. 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.

[adhesive]
Bonding of the polarizing film and the protective film can be performed with an adhesive. The adhesive layer for bonding the polarizing film and the protective film can have a thickness of about 0.01 to 30 μm, preferably 0.01 to 10 μm, more preferably 0.05 to 5 μm. If the thickness of the adhesive layer is within this range, the protective film and the polarizing film to be laminated do not float or peel off, and an adhesive force having no practical problem can be obtained.

In forming the adhesive layer, an appropriate adhesive can be used as appropriate according to the type and purpose of the adherend, and an anchor coating agent can be used as necessary. Examples of the adhesive include a solvent-type adhesive, an emulsion-type adhesive, a pressure-sensitive adhesive, a rewet-adhesive, a polycondensation-type adhesive, a solventless-type adhesive, a film-type adhesive, and a hot-melt-type adhesive. Can be mentioned.

As one of preferable adhesives, there can be mentioned an aqueous adhesive, that is, an adhesive component in which the adhesive component is dissolved or dispersed in water. Examples of adhesive components that can be dissolved in water include polyvinyl alcohol resins. An example of an adhesive component that can be dispersed in water is a urethane resin having a hydrophilic group. The water-based adhesive can be prepared by mixing such an adhesive component with water together with an additional additive added as necessary. Examples of commercially available polyvinyl alcohol resins that can be used as water-based adhesives include “KL-318”, which is a carboxyl group-modified polyvinyl alcohol sold by Kuraray Co., Ltd.

The water-based adhesive can contain a crosslinking agent as necessary. Examples of the crosslinking agent include amine compounds, aldehyde compounds, methylol compounds, water-soluble epoxy resins, isocyanate compounds, and polyvalent metal salts. When a polyvinyl alcohol resin is used as an adhesive component, an aldehyde compound such as glyoxal, a methylol compound such as methylol melamine, a water-soluble epoxy resin, or the like is preferably used as a crosslinking agent.
Here, the water-soluble epoxy resin is, for example, a polyamide obtained by reacting epichlorohydrin with a polyamide polyamine which is a reaction product of a polyalkylene polyamine such as diethylenetriamine or triethylenetetramine and a dicarboxylic acid such as adipic acid. It can be an epoxy resin. An example of a commercially available water-soluble epoxy resin is “Smilease Resin (registered trademark) 650 (30)” sold by Taoka Chemical Co., Ltd.

A polarizing plate can be obtained by applying a water-based adhesive to the adhesive surface of the polarizing film and / or the protective film to be bonded thereto, and bonding them together, followed by drying treatment. Prior to adhesion, it is also effective to subject the protective film to easy adhesion treatment such as saponification treatment, corona discharge treatment, plasma treatment, or primer treatment to enhance wettability. The drying temperature can be about 50 to 100 ° C., for example. After drying treatment, curing at a temperature slightly higher than room temperature, for example, at a temperature of about 30 to 50 ° C. for about 1 to 10 days is preferable in order to further increase the adhesive strength.

Another preferable adhesive is a curable adhesive composition containing an epoxy compound that is cured by irradiation with active energy rays or heating. Here, the curable epoxy compound has at least two epoxy groups in the molecule. In this case, the adhesive between the polarizing film and the protective film is performed by irradiating the applied layer of the adhesive composition with an active energy ray or applying heat to the adhesive composition, and a curable epoxy compound contained in the adhesive. It can carry out by the method of hardening. Curing of the epoxy compound is generally performed by cationic polymerization of the epoxy compound. Further, from the viewpoint of productivity, this curing is preferably performed by irradiation with active energy rays.

From the viewpoint of weather resistance, refractive index, cationic polymerizability, etc., the epoxy compound contained in the curable adhesive composition is preferably one that does not contain an aromatic ring in the molecule. Examples of epoxy compounds that do not contain an aromatic ring in the molecule include hydrogenated epoxy compounds, alicyclic epoxy compounds, and aliphatic epoxy compounds. An epoxy compound suitably used for such a curable adhesive composition is described in detail in, for example, Japanese Patent Application Laid-Open No. 2004-245925, but the outline is also described here.

The hydrogenated epoxy compound is a glycidyl compound obtained by subjecting an aromatic polyhydroxy compound, which is a raw material of an aromatic epoxy compound, to a nuclear hydrogenated polyhydroxy compound obtained by selectively performing a nuclear hydrogenation reaction in the presence of a catalyst and under pressure. It can be etherified. Examples of the aromatic polyhydroxy compound that is a raw material of the aromatic epoxy compound include bisphenols such as bisphenol A, bisphenol F, and bisphenol S; phenol novolac resin, cresol novolac resin, and hydroxybenzaldehyde phenol novolac resin And novolak type resins; polyhydroxy compounds such as tetrahydroxydiphenylmethane, tetrahydroxybenzophenone, and polyvinylphenol. A glycidyl ether can be obtained by performing a nuclear hydrogenation reaction on such an aromatic polyhydroxy compound and reacting the resulting hydrogenated polyhydroxy compound with epichlorohydrin. Suitable hydrogenated epoxy compounds include hydrogenated glycidyl ether of bisphenol A.

The alicyclic epoxy compound is a compound having at least one epoxy group bonded to the alicyclic ring in the molecule. The “epoxy group bonded to the alicyclic ring” means a bridged oxygen atom —O— in the structure represented by the following formula, wherein m is an integer of 2 to 5.

A compound in which one or more hydrogen atoms in (CH ₂ ) _m in this formula are removed and bonded to another chemical structure can be an alicyclic epoxy compound. Further, one or more hydrogen atoms in (CH ₂ ) _m forming the alicyclic ring may be appropriately substituted with a linear alkyl group such as a methyl group or an ethyl group. Among alicyclic epoxy compounds, an epoxy compound having an oxabicyclohexane ring (m = 3 in the above formula) or an oxabicycloheptane ring (m = 4 in the above formula) has excellent adhesion. It is preferably used from the indication. Specific examples of the alicyclic epoxy compound are listed below. Here, the compound names are given first, and then the chemical formulas corresponding to each are shown, and the same reference numerals are given to the compound names and the chemical formulas corresponding thereto.

A: 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate,
B: 3,4-epoxy-6-methylcyclohexylmethyl 3,4-epoxy-6-methylcyclohexanecarboxylate,
C: ethylene bis (3,4-epoxycyclohexanecarboxylate),
D: Bis (3,4-epoxycyclohexylmethyl) adipate,
E: bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate,
F: diethylene glycol bis (3,4-epoxycyclohexyl methyl ether), G: ethylene glycol bis (3,4-epoxycyclohexyl methyl ether),
H: 2,3,14,15-diepoxy-7,11,18,21-tetraoxatrispiro [5.2.2.5.2.2] henicosane,
I: 3- (3,4-epoxycyclohexyl) -8,9-epoxy-1,5-dioxaspiro [5.5] undecane,
J: 4-vinylcyclohexene dioxide
K: Limonene dioxide
L: bis (2,3-epoxycyclopentyl) ether,
M: Dicyclopentadiene dioxide and the like.

The aliphatic epoxy compound can be an aliphatic polyhydric alcohol or a polyglycidyl ether of an alkylene oxide adduct thereof. More specifically, diglycidyl ether of propylene glycol; diglycidyl ether of 1,4-butanediol; diglycidyl ether of 1,6-hexanediol; triglycidyl ether of glycerin; triglycidyl ether of trimethylolpropane; ethylene Polyglycidyl ether of polyether polyol (for example, diglycidyl ether of polyethylene glycol) obtained by adding alkylene oxide (ethylene oxide or propylene oxide) to aliphatic polyhydric alcohol such as glycol, propylene glycol, and glycerin Can be mentioned.

In the curable adhesive composition, the epoxy compound may be used alone or in combination of two or more. Among these, the epoxy compound preferably includes an alicyclic epoxy compound having at least one epoxy group bonded to the alicyclic ring in the molecule.

The epoxy compound used in the curable adhesive composition usually has an epoxy equivalent in the range of 30 to 3,000 g / equivalent, and this epoxy equivalent is preferably in the range of 50 to 1,500 g / equivalent. When an epoxy compound having an epoxy equivalent of less than 30 g / equivalent is used, there is a possibility that the flexibility of the polarizing plate after curing is lowered or the adhesive strength is lowered. On the other hand, in a compound having an epoxy equivalent exceeding 3,000 g / equivalent soot, compatibility with other components contained in the adhesive composition may be reduced.

From the viewpoint of reactivity, cationic polymerization is preferably used as the curing reaction of the epoxy compound. For that purpose, it is preferable to mix | blend a cationic polymerization initiator with the curable adhesive composition containing an epoxy compound. The cationic polymerization initiator generates a cationic species or a Lewis acid by irradiation or heating with active energy rays such as visible light, ultraviolet rays, X-rays, and electron beams, and initiates an epoxy group polymerization reaction. From the viewpoint of workability, it is preferable that the cationic polymerization initiator is provided with latency. Hereinafter, a cationic polymerization initiator that generates a cationic species or Lewis acid by irradiation of active energy rays and initiates a polymerization reaction of an epoxy group is referred to as a “photo cationic polymerization initiator”, and generates a cationic species or a Lewis acid by heat. The cationic polymerization initiator that initiates the polymerization reaction of the epoxy group is referred to as “thermal cationic polymerization initiator”.

The method of curing the adhesive composition by irradiation with active energy rays using a cationic photopolymerization initiator enables curing at normal temperature and humidity, reducing the need to consider the distortion due to heat resistance or expansion of the polarizing film. And it is advantageous in that the protective film and the polarizing film can be satisfactorily bonded. In addition, since the cationic photopolymerization initiator acts catalytically by light, it is excellent in storage stability and workability even when mixed with an epoxy compound.

Examples of the photocationic polymerization initiator include aromatic diazonium salts; onium salts such as aromatic iodonium salts and aromatic sulfonium salts, and iron-allene complexes. The compounding amount of the photocationic polymerization initiator is usually 0.5 to 20 parts by weight, preferably 1 part by weight or more and preferably 15 parts by weight or less based on 100 parts by weight of the epoxy compound.
If the amount of the cationic photopolymerization initiator is less than 0.5 parts by weight based on 100 parts by weight of the epoxy compound, the curing becomes insufficient, and the mechanical strength and adhesive strength of the cured product tend to be reduced.
On the other hand, when the blending amount of the cationic photopolymerization initiator exceeds 20 parts by weight with respect to 100 parts by weight of the epoxy compound, the ionic substance in the cured product increases, resulting in an increase in the hygroscopic property of the cured product and durability performance. May be reduced.

When using a photocationic polymerization initiator, the curable adhesive composition may further contain a photosensitizer as necessary. By using a photosensitizer, the reactivity of cationic polymerization can be improved, and the mechanical strength and adhesive strength of the cured product can be improved. Examples of the photosensitizer include carbonyl compounds, organic sulfur compounds, persulfides, redox compounds, azo compounds, diazo compounds, halogen compounds, and photoreducible dyes. When a photosensitizer is blended, the amount is preferably in the range of 0.1 to 20 parts by weight with respect to 100 parts by weight of the curable adhesive composition. Further, a sensitizing aid such as a naphthoquinone derivative may be used for improving the curing rate.

On the other hand, examples of the thermal cationic polymerization initiator include benzylsulfonium salt, thiophenium salt, thioranium salt, benzylammonium, pyridinium salt, hydrazinium salt, carboxylic acid ester, sulfonic acid ester, and amine imide.

The curable adhesive composition containing the epoxy compound is preferably cured by photocationic polymerization as described above, but can be cured by thermal cationic polymerization in the presence of the above-mentioned thermal cationic polymerization initiator. Cationic polymerization and thermal cationic polymerization can be used in combination. When photocationic polymerization and thermal cationic polymerization are used in combination, the curable adhesive composition preferably contains both a photocationic polymerization initiator and a thermal cationic polymerization initiator.

The curable adhesive composition may further contain a compound that promotes cationic polymerization, such as an oxetane compound or a polyol compound. An oxetane compound is a compound having a 4-membered ring ether in the molecule. When the oxetane compound is blended, the amount thereof is usually 5 to 95% by weight, preferably 5 to 50% by weight in the curable adhesive composition. The polyol compound may be alkylene glycol including ethylene glycol, hexamethylene glycol, polyethylene glycol or the like, or an oligomer thereof, polyester polyol, polycaprolactone polyol, polycarbonate polyol and the like. When a polyol compound is blended, the amount is usually 50% by weight or less, preferably 30% by weight or less in the curable adhesive composition.

The curable adhesive composition may contain a (meth) acrylic compound that is radically polymerizable. 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.

In this case, the curable adhesive composition preferably contains a radical photopolymerization 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.

In addition, the curable adhesive composition may have other additives such as ion trapping agents, antioxidants, chain transfer agents, sensitizers, tackifiers, thermoplastic resins, fillers, as long as the adhesiveness is not impaired. Agents, flow modifiers, plasticizers, antifoaming agents, and the like. Examples of the ion trapping agent include inorganic compounds including powdered bismuth-based, antimony-based, magnesium-based, aluminum-based, calcium-based, titanium-based, and mixed systems thereof. Examples of the antioxidant include And hindered phenolic antioxidants.

After applying the curable adhesive composition containing the epoxy compound to the adhesive surface of the polarizing film or the protective film, or to the adhesive surface of both of them, it is pasted on the adhesive-coated surface, and active energy rays. The polarizing film and the protective film can be bonded by curing the uncured adhesive layer by irradiating or heating. As an adhesive coating method, for example, various coating methods such as a doctor blade, a wire bar, a die coater, a comma coater, and a gravure coater can be adopted.

This curable adhesive composition can basically be used as a solvent-free adhesive that does not substantially contain a solvent, but each coating system has an optimum viscosity range, so that the viscosity is adjusted. For this purpose, a solvent may be contained. The solvent is preferably an organic solvent that dissolves each component including an epoxy compound well without degrading the optical performance of the polarizing film. For example, hydrocarbons typified by toluene, typified by ethyl acetate, etc. Esters can be used.

When the adhesive composition is cured by irradiation with active energy rays, the above-mentioned various types of active energy rays can be used, but since the handling is easy and the amount of irradiation light is easy to control, ultraviolet rays are not emitted. Preferably used. Active energy rays such as ultraviolet irradiation intensity and irradiation dose do not affect various optical performance including polarization degree of polarizing film, and various optical performance including transparency and retardation characteristics of protective film. Therefore, it is determined as appropriate so as to maintain an appropriate productivity.

When the adhesive composition is cured by heat, it can be heated by a generally known method. Usually, heating is performed at a temperature higher than the temperature at which the thermal cationic polymerization initiator compounded in the curable adhesive composition generates cationic species and Lewis acid, and the specific heating temperature is, for example, about 50 to 200 ° C. .

[Peeling film]
The release film is a film that can be peeled at a desired timing after being laminated on the polarizing film. “Peelable” means that the polarizing film and the release film can be separated. It is preferable that the polarizing film and the release film can be peeled without being damaged or damaged.
In view of handling properties, transparency, inexpensiveness, and the like, the release film is, for example, a chain polyolefin resin such as polyethylene resin or polypropylene resin; a cellulose ester resin such as cellulose triacetate or cellulose diacetate; or polyethylene terephthalate. And a transparent resin film made of a polyester resin such as 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 also be used as a release film.
Among these, a film made of polyethylene terephthalate, cellulose triacetate, or polymethyl methacrylate resin can be suitably used.

In the second step, in order to volatilize the volatile liquid used for laminating the polarizing film and the release film by heating, the moisture permeability of at least one of the protective film and the release film is 400 g / m ² · 24 hr or more. It is preferable that it is 420 g / m ² · 24 hr or more. If the moisture permeability is within this range, the volatile liquid can be efficiently volatilized and removed in the subsequent second step, so that productivity can be further improved.

For example, when a cellulose resin film is used as the protective film, a (meth) acrylic resin film is preferably used as the release film. When a polyolefin resin film is used as the protective film, the release film is a cellulose resin film. Is preferably used.

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

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

[Volatile liquid]
The volatile liquid used for lamination between the polarizing film and the release film is a liquid that can be volatilized by the heat treatment in the second step, and preferably a liquid that does not adversely affect the polarizing film. An additive such as an antistatic agent may be added as long as it does not have an adverse effect. Examples of the volatile liquid 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.

In this step, a long polarizing film roll (rolled product), a long protective film roll, and a long release film roll are prepared, and the film is conveyed while continuously unwinding them. Each film is conveyed so that the longitudinal direction thereof is the conveyance direction. A guide roll for supporting the traveling film is appropriately provided in the film conveyance path. Usually, the conveyance direction (film longitudinal direction) of a polarizing film, the conveyance direction (film longitudinal direction) of a protective film, and the conveyance direction (film longitudinal direction) of a peeling film are parallel.
In this step, a protective film is bonded to one surface of the polarizing film via an adhesive layer, and a release film is laminated to the other surface of the polarizing film via a volatile liquid. The lamination of the protective film and the lamination of the release film were performed by laminating the protective film, the polarizing film, and the release film so that their longitudinal directions (conveying directions) were parallel and passing between the pair of lamination rolls. This can be done by pressing the film from above and below.
At this time, an adhesive is applied between the polarizing film and the protective film, and a volatile liquid is applied between the polarizing film and the release film before passing between the pair of bonding rolls.

Here, an example in which the protective film, the polarizing film, and the release film are bonded (laminated) at the same time has been described. Of course, the bonding of the protective film and the polarizing film and the lamination of the release film and the polarizing film are sequentially performed. It may be done automatically.

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 in which a layer made of a volatile liquid is interposed between the polarizing film and the release film and the release film is laminated on the polarizing film, the process of drying and volatilizing the adhesive and the volatile liquid Also in (2nd process), the fracture | rupture of a polarizing film can be suppressed effectively. Moreover, interposing a volatile liquid between a polarizing film and a peeling film also has an 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.

In bonding a protective film to a polarizing film, the bonding surface of the polarizing film and / or the protective film has a plasma treatment, a corona treatment, an ultraviolet irradiation treatment, a frame (flame) treatment, a Ken to improve adhesion. An easy adhesion treatment such as a crystallization treatment can be performed. Among these, it is preferable to perform plasma treatment, corona treatment or saponification treatment. For example, when the protective film is made of a cyclic polyolefin-based resin, the bonding surface of the protective film can be subjected to plasma treatment or corona treatment. Moreover, when a protective film consists of cellulose-ester-type resin, a saponification process can be given to the bonding surface of a protective film. Examples of the saponification treatment include a method of immersing in an alkaline aqueous solution such as sodium hydroxide or potassium hydroxide. In addition, it is also useful to perform the same treatment as the protective film in order to improve the wettability of the volatile liquid to the release film.

In the present invention, when using a water-based adhesive or a curable adhesive containing an epoxy compound that is cured by heating, it is preferable to volatilize the volatile liquid and dry or cure the adhesive layer in the next second step. Moreover, when using the curable adhesive hardened | cured by irradiation of an active energy ray, it is preferable to irradiate and harden an active energy ray before a 2nd process.

[2] Second Step This step is a step for removing volatile liquids by volatilization. The volatile liquid is preferably removed by volatilization by heating. By this heat treatment, the release film is laminated directly on the surface of the polarizing film with an appropriate adhesion.
The drying temperature is preferably 30 to 90 ° C. If it is less than 30 ° C., it takes a long time to dry, and there is a possibility that an appearance defect may occur. If the drying temperature exceeds 90 ° C., the polarizing performance of the polarizing film 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.

By laminating the release film via a layer made of a volatile liquid on the polarizing film, the heating temperature in this step can be increased to, for example, about 60 ° C. or more and about 90 ° C. or less. That is, even if the heating temperature is set high, in addition to being able to suppress the breakage of the polarizing film, the high-temperature heating can provide a single-side protective polarizing plate with a small shrinkage rate of the polarizing film and thus high dimensional stability. . 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 cannot be set high, and it has been difficult to obtain a single-side protective polarizing plate having a low shrinkage rate.

After volatilizing and removing the volatile liquid, it is preferable to roll up a laminate having a protective film, a polarizing film, and a release film in this order to form a roll.

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 curing, an additional storage process may be provided. The storage period is usually 1 day or longer, 7 days or longer, or 1 month or longer. Usually, the storage period is one year or less. As will be described later, the present invention is remarkably effective when the storage period is one month or longer. The storage temperature is, for example, in the range of 10-30 ° C., and the relative humidity is, for example, 0-70% RH.

[3] Third Step This step is a step of peeling the release film from the laminate. In the second step, the release film is laminated with an appropriate adhesion, but when the storage period from the second step to the third step is 7 days or more, especially the storage period from the second step to the third step is When it becomes 1 month or more, the adhesive force of a polarizing film and a peeling film rises, and peeling may become difficult.

In this step, in order to solve this problem, the release film is peeled so that the transport direction of the peel film after the peel point is substantially horizontal to the transport direction of the laminate. It is preferable that the angle (change in transport angle) formed by the transport direction of the release film after the release point and the transport direction of the laminate is within 30 °. The change in the transport angle is more preferably performed within 15 °, and further preferably performed within 5 °. Referring to FIG. 1, the conveyance angle change referred to in the present invention is an angle 20 formed by the conveyance direction 13 of the laminate before the peeling point 31 and the conveyance direction 14 of the release film after the peeling point 31.

In addition, the angle formed by the transport direction of the polarizing film and the protective film after the peeling point and the transport direction of the laminate (change in the transport angle of the single-sided protective polarizing plate) is preferably 15 ° or more, and 30 ° or more. More preferably. By doing in this way, generation | occurrence | production of the peeling defect by flapping of the protective film at the time of film conveyance can be suppressed. Referring to FIG. 1, the conveyance angle change of the single-sided protective polarizing plate referred to in the present invention is an angle formed by the conveyance direction 13 of the laminate before the peeling point 31 and the conveyance direction 15 of the single-sided protective polarizing plate after the peeling point 31. 21

That is, as described above, it is preferable that the third step causes the single-sided protective polarizing plate to be peeled off from the laminate.

The details of the mechanism are unknown, but if the peel film transport angle exceeds 15 ° before and after the peel point, the peel force tends to exceed 0.5 N / 25 mm. The peeling force between the polarizing film and the release film in the third step 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 strength between the polarizing film and the peeling film is small, so that the peeling film partially peels off or is stored in a state where the single-sided protective polarizing plate is rolled. In some cases, the polarizing film may tear along the stretching direction (in a direction parallel to the stretching direction). Moreover, since it will become difficult to peel a peeling film from a polarizing film when peeling force exceeds 0.5 N / 25mm, when peeling a peeling film, a polarizing film may tear along a extending direction.

Here, the peel force is obtained by cutting a single-side protective polarizing plate on which a release film is laminated to a width of 25 mm, obtaining a measurement sample, and using a precision universal testing machine “Autograph AGS-50NX” manufactured by Shimadzu Corporation. Can be measured. When changing the transport angle of the single-sided protective polarizing plate, fix the release film surface to glass (the angle 20 formed by the transport direction 13 of the laminate and the transport direction 14 of the release film in FIG. 1 corresponds to 0 °), It is obtained by measuring the force when the single-sided protective polarizing plate is gripped and peeled off at the same angle as the conveyance angle change employed in the third step.

When changing the peel angle of the release film (corresponding to the angle 20 between the transport direction 13 of the laminate and the transport direction 14 of the release film in FIG. 2), the single-sided protective polarizing plate is fixed to the glass, the release film is gripped, It is calculated | required by measuring the force when peeling at the same angle as the conveyance angle change employ | adopted at 3 processes.

When the transport direction of the release film or the transport direction of the single-sided protective polarizing plate is not horizontal with respect to the transport direction of the laminate, by using a jig that fixes the angle of the laminate film and the angle of the release film, The peel force can be measured.

The measurement of peeling force is performed in an environment where the peeling speed is 100 mm / min, the temperature is 23 ± 2 ° C., and the relative humidity is 50 ± 5%.

[4] Other steps The single-sided protective polarizing plate of the present invention may be used in a form in which a pressure-sensitive adhesive layer is formed on the polarizing film surface and bonded to the liquid crystal cell as it is. Moreover, it can utilize suitably also as a manufacture intermediate body of the double-sided protective polarizing plate by which the protective film was bonded on both surfaces of the polarizing plate.

As the pressure-sensitive adhesive, a conventionally known appropriate pressure-sensitive adhesive can be used. For example, a (meth) acrylic pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, a polyester-based pressure-sensitive adhesive, a polyamide-based pressure-sensitive adhesive, or a polyether-based pressure-sensitive adhesive. Examples thereof include an adhesive, a fluorine-based adhesive, and a rubber-based adhesive.
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 can be provided by a method in which the 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, a gravure coater, or the like and dried. The sheet-like pressure-sensitive adhesive formed on the plastic film (referred to as a separate film) can also be provided by a method of transferring 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. The thickness of the pressure-sensitive adhesive can be 2 to 40 μm, for example.

Also when laminating another protective film on the polarizing film surface of the single-sided protective polarizing plate, the adhesive or pressure-sensitive adhesive described above can be used. The protective film used here may be the same as or different from the protective film used in the single-side protective polarizing plate. It is also a useful technique to make a functional film such as a retardation film or a brightness enhancement film.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited by these examples. In the examples,% and parts representing the content and the amount used are based on weight unless otherwise specified.

(1) Measurement of thickness:
Measurement was performed using a digital micrometer “MH-15M” manufactured by Nikon Corporation.

(2) Measurement of peeling force:
Measurement was performed using a precision universal testing machine “Autograph AG1-S” manufactured by Shimadzu Corporation. The peeling force was measured in an environment where the peeling speed was 100 mm / min, the temperature was 23 ± 2 ° C., and the relative humidity was 50 ± 5%.

(3) Measurement of moisture permeability:
The moisture permeability was measured based on JIS Z 0208. The temperature and humidity conditions were 40 degrees and 90% RH.

[Production Example 1] Production of polarizing film A polyvinyl alcohol film having a thickness of 20 µm (average polymerization degree of about 2400, saponification degree of 99.9 mol% or more) is uniaxially stretched by about 4 times by dry stretching, and further maintained in a tension state. The sample was immersed in pure water at 40 ° C. for 40 seconds, and then immersed in an aqueous solution having an iodine / potassium iodide / water weight ratio of 0.052 / 5.7 / 100 at 28 ° C. for 30 seconds to perform a dyeing treatment. It was. Thereafter, it was immersed in an aqueous solution having a weight ratio of potassium iodide / boric acid / water of 11.0 / 6.2 / 100 at 70 ° C. for 120 seconds. Subsequently, after washing with pure water at 8 ° C. for 15 seconds, the film is dried at 60 ° C. for 50 seconds and then at 75 ° C. for 20 seconds while being held at a tension of 300 N, and iodine is adsorbed and oriented on the polyvinyl alcohol film. A polarizing film having a thickness of 7 μm was obtained.

[Production Example 2] Preparation of aqueous adhesive 3 parts by weight of a carboxyl group-modified polyvinyl alcohol [trade name “KL-318” obtained from Kuraray Co., Ltd.] was dissolved in 100 parts by weight of water, and a water-soluble epoxy was dissolved in the aqueous solution. 1.5 parts by weight of a resin-based polyamide epoxy additive [trade name “Smileise Resin (registered trademark) 650 (30)” obtained from Taoka Chemical Co., Ltd., aqueous solution with a solid content of 30 wt%] was added. A water-based adhesive was prepared.

[Protective films A and B and release films C and D]
The following four types of protective films and release films were prepared.
Protective film A: Film obtained by saponifying a triacetylcellulose film manufactured by Konica Minolta, Inc .; KC2UAW (thickness 25 μm, moisture permeability = 1207 g / m ² · 24 hr)
Protective film B: Cyclic polyolefin resin film manufactured by Zeon Corporation; ZF14-013 (thickness 13 μm, moisture permeability = 30 g / m ² · 24 hr)
Peeling film C: Triacetyl cellulose film manufactured by FUJIFILM Corporation; TD80UL (thickness 80 μm, moisture permeability = 502 g / m ² · 24 hr)
Release film D: Polymethyl methacrylate resin film manufactured by Sumitomo Chemical Co., Ltd. (thickness 80 μm, moisture permeability = 50 g / m ² · 24 hr)

[Example 1] Production of single-sided protective polarizing plate 1 The polarizing film obtained in Production Example 1 was continuously conveyed and the protective film A was continuously unwound from the roll of the protective film A. The release film D was continuously unwound from the roll. Next, a water-based adhesive is injected between the polarizing film and the protective film A, and pure water is injected between the polarizing film and the release film D, passing through a bonding roll, and the protective film A / water-based adhesive layer. It was set as the laminated film consisting of / polarizing film / pure water / release film D (first step). Subsequently, the laminated film is transported and heated at 80 ° C. for 300 seconds in a drying furnace to volatilize and remove pure water intervening between the polarizing film and the release film D while drying the aqueous adhesive layer. And the single-sided protective polarizing plate 1 with a peeling film was obtained (2nd process). During the production of the single-side protective polarizing plate 1 with a release film, the polarizing film was not broken and the polarizing plate was not wrinkled. Thus, the roll of the produced single-sided protective polarizing plate 1 with a release film was stored in an environment of a temperature of 23 ° C. and a humidity of 55% for 3 months.

After storage, when the release film D was peeled from the single-sided protective polarizing plate 1 with a release film, the release film D was peeled with the change in the transport angle of the release film D before and after the release point as 0 °. The peeling force was 0.33 N / 25 mm, and there was no problem in peeling.

[Example 2]
A single-sided protective polarizing plate 1 was prepared in the same manner as in Example 1, wound up on a roll, and stored for 3 months in an environment having a temperature of 23 ° C. and a humidity of 55%. When the release film D was peeled from the single-sided protective polarizing plate 1 with a release film after storage, the release film D was peeled off with the change in the transport angle of the release film before and after the release point being 3 °. The peeling force was 0.35 N / 25 mm, and there was no problem in peeling.

[Example 3]
A single-sided protective polarizing plate 1 was prepared in the same manner as in Example 1, wound up on a roll, and stored for 3 months in an environment having a temperature of 23 ° C. and a humidity of 55%. When the release film D was peeled from the single-sided protective polarizing plate 1 with a release film after storage, the release film D was peeled off with the change in the transport angle of the release film before and after the release point as 10 °. The peeling force was 0.42 N / 25 mm, and although peeling occurred during the peeling, the peeling was possible.

[Comparative Example 1]
A single-sided protective polarizing plate 1 was prepared in the same manner as in Example 1, wound up on a roll, and stored for 3 months in an environment having a temperature of 23 ° C. and a humidity of 55%. After the storage, when the release film D was peeled from the single-sided protective polarizing plate 1 with the release film, the release film D was peeled at 90 ° as the change in the transport angle of the release film before and after the release point. The peeling force was 1.36 N / 25 mm, and peeling was difficult.

[Example 4] Production of single-sided protective polarizing plate 2 The polarizing film obtained in Production Example 1 was continuously conveyed and the protective film B was continuously unwound from the roll of the protective film B. The release film C was continuously unwound from the roll. Next, a water-based adhesive is injected between the polarizing film and the protective film B, and pure water is injected between the polarizing film and the release film C, and the protective film B / water-based adhesive layer is passed through a bonding roll. It was set as the laminated film consisting of / polarizing film / pure water / release film C (first step). Subsequently, the laminated film is transported and heated at 80 ° C. for 300 seconds in a drying furnace to volatilize and remove the pure water intervening between the polarizing film and the release film C along with drying of the aqueous adhesive layer. And the single-sided protective polarizing plate 2 with a peeling film was obtained (2nd process). During the production of the single-sided protective polarizing plate 2 with a release film, the polarizing film was not broken and the polarizing plate was not wrinkled. Thus, the roll of the produced single-sided protective polarizing plate 2 with a release film was stored in an environment of a temperature of 23 ° C. and a humidity of 55% for 3 months.

After storage, when the release film C was peeled from the single-side protective polarizing plate 2 with a release film, the release film C was peeled off with the change in the transport angle of the release film C before and after the release point being 0 °. The peeling force was 0.1 N / 25 mm, and there was no problem in peeling.

[Example 5]
A single-sided protective polarizing plate 2 was prepared in the same manner as in Example 4, wound on a roll, and stored for 3 months in an environment having a temperature of 23 ° C. and a humidity of 55%. When the release film C was peeled from the single-sided protective polarizing plate 2 with the release film after storage, the release film C was peeled off with the change in the transport angle of the release film before and after the release point being 3 °. The peeling force was 0.3 N / 25 mm, and there was no problem in peeling.

[Example 6]
A single-sided protective polarizing plate 2 was prepared in the same manner as in Example 4, wound on a roll, and stored for 3 months in an environment having a temperature of 23 ° C. and a humidity of 55%. When the release film C was peeled from the single-sided protective polarizing plate 2 with a release film after storage, the release film C was peeled off with a change in the transport angle of the release film before and after the release point as 10 °. The peeling force was 0.5 N / 25 mm, and peeling was possible although zipping occurred.

[Comparative Example 2]
A single-sided protective polarizing plate 2 was prepared in the same manner as in Example 4, wound on a roll, and stored for 3 months in an environment having a temperature of 23 ° C. and a humidity of 55%. After storage, when the release film C was peeled from the single-sided protective polarizing plate 2 with a release film, the release film C was peeled at 90 ° as the change in the transport angle of the release film before and after the release point. The peeling force was 1.2 N / 25 mm, and peeling was difficult.

The results are shown in Table 1. In addition, the result of the peeling test was evaluated based on the following criteria.
(Double-circle): There was no problem, such as a fracture | rupture of a film, and it was able to peel.
○: Although peeling occurred when the film was peeled off, the film could be peeled off.
X: Film breakage or the like occurred, and peeling was difficult.

DESCRIPTION OF SYMBOLS 10 Laminate 11 Single-sided protective polarizing plate 12 Release film 13 Transport direction of laminate 14 Transport direction of release film 15 Transport direction of single-sided protective polarizing plate 20 Change in transport angle 21 Change in transport angle of single-sided protective film 30 Roll 31 Release point

Claims (4)

1. A protective film is bonded to one surface of the polarizing film via an adhesive layer, and a release film is laminated to the other surface of the polarizing film via a layer made of a volatile liquid to obtain a laminate. 1 process,
   A second step of volatilizing the volatile liquid;
   The manufacturing method of the single-sided protective polarizing plate including the 3rd process of peeling the said peeling film so that the conveyance direction of the said peeling film after a peeling point may become substantially horizontal with respect to the conveyance direction of the said laminated body. .
2. 2. The method for producing a polarizing plate according to claim 1, wherein an angle formed by the transport direction of the release film after the release point and the transport direction of the laminate is within 15 °.
3. The manufacturing method of the polarizing plate of Claim 1 or 2 including the process of winding up the laminated body which has a protective film, a polarizing film, and a peeling film in this order before the process of peeling a peeling film, and obtaining a roll.
4. The method for producing a polarizing plate according to claim 1, wherein the volatile liquid contains water.

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