KR20160108096A

KR20160108096A - Stretched film, polarizing film and polarizing plate comprising same

Info

Publication number: KR20160108096A
Application number: KR1020150088907A
Authority: KR
Inventors: 유이치로 구나이; 나오코 다케노쿠마
Original assignee: 스미또모 가가꾸 가부시키가이샤
Priority date: 2015-03-05
Filing date: 2015-06-23
Publication date: 2016-09-19
Also published as: JP6045623B2; CN106199804B; JP2016161897A; TW201632350A; KR101769202B1; TWI592308B; CN106199804A

Abstract

(1) using the crystal melting peak temperature T (K) measured by differential scanning calorimetry measurement of a stretched film as a stretched film comprising a polyvinyl alcohol-based resin containing lamellar crystals, A stretched film for use in the production of a polarizing film, wherein a thickness L (nm) of the crystal is 13.0 nm or more and 45.0 nm or less.
L = 0.66 x {516 / (516-T)} (1)

Description

(STRETCHED FILM, POLARIZING FILM AND POLARIZING PLATE COMPRISING SAME)

The present invention relates to a stretched film, a polarizing film and a polarizing plate comprising the same.

BACKGROUND ART A polarizing plate is widely used in an image display apparatus typified by a liquid crystal display apparatus. As the polarizing plate, a polarizing film formed by adsorbing and orienting a dichroic dye such as iodine on a polyvinyl alcohol-based resin film is generally formed by bonding a protective film to one or both sides of the polarizing film. 2. Description of the Related Art In recent years, as polarizers and polarizing films have become thinner and thinner, they have become more and more required as they are developed in mobile devices and thin-type televisions in image displays.

Japanese Patent No. 4691205 (Patent Document 1) discloses a method in which a polyvinyl alcohol-based resin layer is formed on a base film, and the base film is integrally stretched and dyed to obtain a polarizing film, whereby a polyvinyl alcohol- It is described that a thin polarizing film can be produced more uniformly as compared with a method of producing a polarizing film by a single layer body.

Since the polyvinyl alcohol resin constituting the polarizing film is hydrophilic, there is a problem that it is liable to be dissolved in an aqueous solution (hereinafter also referred to as " solubility ") in a manufacturing process such as immersing a stretched film in a dyeing solution. When the polyvinyl alcohol-based resin is dissolved, appearance defects, a decrease in film strength, and a decrease in polarization performance are caused. In the method of forming a polyvinyl alcohol-based resin layer on a base film and stretching and dyeing it integrally with the base material to obtain a polarizing film, complete breakage of the polyvinyl alcohol-based resin layer can be prevented, The problem that the vinyl alcohol-based resin is dissolved can not be solved.

Patent Document 1 discloses that an insolubilization step of immersing a previously stretched laminate in an aqueous boric acid solution is performed before immersing the polyvinyl alcohol-based resin layer in the dyeing step.

However, when the insolubilization step is carried out, the manufacturing process becomes troublesome and the stretched film made of the polyvinyl alcohol-based resin subjected to the insolubilization step has a problem that the permeability of the dyeing solution in the dyeing step (hereinafter also referred to as " . If the dyeing time is prolonged in order to sufficiently penetrate the dyeing solution, the productivity is lowered and the film strength may be lowered.

An object of the present invention is to provide a stretched film having reduced solubility and having excellent dyeability, a polarizing film produced using the stretched film, and a polarizing plate.

The present invention provides a stretched film, a polarizing film and a polarizing plate described below.

[1] A stretched film made of a polyvinyl alcohol-based resin containing a lamellar crystal,

Wherein a thickness L (nm) of the lamellar crystal calculated by the following formula (1) is 13.0 nm or more and 45.0 nm or less, using a crystal melting peak temperature T (K) measured by differential scanning calorimetry measurement of the stretched film: A stretched film used for manufacturing a film.

L = 0.66 x {516 / (516-T)} (1)

[2] The stretched film according to [1], wherein the polyvinyl alcohol-based resin contains, as a constituent monomer, a monomer for adjusting the thickness L (nm) of the lamellar crystal.

[3] A stretched film according to [1] or [2], which is obtained by stretching a polyvinyl alcohol-based resin layer provided on a base film.

[4] A polarizing film obtained by dyeing a stretched film according to any one of [1] to [3] with a dichroic dye.

[5] The polarizing film according to [4], wherein the piercing strength per unit thickness is 6.0 g / 탆 or more.

[6] A polarizing plate described in [4] or [5]

And a protective film laminated on at least one side of the polarizing film.

According to the present invention, it is possible to provide a stretched film having excellent dyeability while suppressing solubility, a polarizing film produced using the stretched film, and a polarizing plate.

1 is a schematic diagram showing a part of a polymer chain constituting a lamellar crystal.
2 is a schematic cross-sectional view showing an example of the layer structure of the polarizing plate according to the present invention.
3 is a schematic cross-sectional view showing another example of the layer structure of the polarizing plate according to the present invention.
4 is a flow chart showing a preferred example of a method for producing a polarizing plate according to the present invention.
5 is a schematic sectional view showing an example of the layer structure of the laminated film obtained in the resin layer forming step.
6 is a schematic cross-sectional view showing an example of the layer structure of a stretched laminated film obtained in the stretching step.
Fig. 7 is a schematic sectional view showing an example of the layer structure of the polarizing laminated film obtained in the dyeing step. Fig.
8 is a schematic cross-sectional view showing an example of the layer structure of the bonding film obtained in the first bonding step.

The stretched film according to the present invention is used for producing a polarizing film. The stretched film is made of a polyvinyl alcohol-based resin containing lamellar crystals. The lamellar crystal contained in the polyvinyl alcohol-based resin has a thickness L (nm) determined by the following formula (1) using a crystal melting peak temperature T (K) measured by differential scanning calorimetry (DSC) nm or more and 45.0 nm or less. On the other hand, it is known that the thickness L (nm) of the lamellar type crystal can be calculated by the following formula (1).

L (nm) = 0.66 x {516 / (516-T)} (1)

The stretched film is formed by stretching a polyvinyl alcohol-based resin. The method of forming the polyvinyl alcohol-based resin is not particularly limited, and a film can be formed by a known method. However, from the viewpoint of easily obtaining a polarizing film having a small thickness and excellent handling property of a polarizing film of the thin film during the process, A method of applying a solution of a vinyl alcohol resin on a base film to form a film is preferable. The method of stretching after forming the polyvinyl alcohol-based resin is not limited, but is preferably uniaxial stretching.

The thickness of the stretched film is appropriately selected depending on whether it is further stretched in the process of producing the polarizing film. For example, the thickness of the stretched film may be 30 占 퐉 or less, more preferably 20 占 퐉 or less, but preferably 10 占 퐉 or less from the viewpoint of thinning of the polarizing plate, More preferably 8 占 퐉 or less. The thickness of the stretched film is usually 2 占 퐉 or more. On the other hand, when the polarizing film is further stretched to produce a polarizing film, it is suitably used even if it is thicker than the above-mentioned thickness.

(Polyvinyl alcohol-based resin)

The average degree of polymerization of the polyvinyl alcohol-based resin constituting the stretched film is preferably 100 to 10,000, more preferably 1,500 to 8,000, and still more preferably 2,000 to 5,000. The average degree of polymerization of the polyvinyl alcohol resin can also be determined in accordance with JIS K 6726 (1994).

(Lamellar type crystal)

It is known that a polyvinyl alcohol-based resin forms a folded structure crystal, which is generally called a lamellar crystal, in which a polymer chain is folded into multiple layers. 1 is a schematic diagram showing a part of a polymer chain constituting a lamellar crystal. The lamellar type crystal 50 is formed by folding the polymer chains 51 into multiple folds in the width direction to form a folded structure, and these folded structures are successively formed in multiple layers even in the inner direction. The thickness L of the lamellar crystal 50 is the distance in the longitudinal direction of the polymer chain 51 forming the folded structure. The width X of the lamellar-shaped crystal 50 is the distance in the folding direction of the polymer chain 51, which increases with the number of times of folding. (Y) of the lamellar crystal 2 is the distance in the inner direction of the folded structure by the polymer chain 51. [

In the lamellar type crystal 50, the thickness L affects the stability. The larger the thickness L is, the more stable the lamellar crystal 51 is. The present inventors have found that when the thickness (L) of a lamellar crystal contained in a polyvinyl alcohol-based resin constituting a stretched film is 13.0 nm or more and 45.0 nm or less, solubility is suppressed and dyeability is good. When the stretched film of the present invention is used, since the dissolution of the polyvinyl alcohol-based resin into a dyeing aqueous solution or the like can be suppressed, a polarizing film having good appearance, excellent film strength and excellent polarization performance can be obtained. In addition, since the dyeability is good, high productivity can be maintained in the production process of the polarizing film.

If the thickness (L) of the lamellar-type crystal is less than 13.0 nm, polyvinyl alcohol-based resin is liable to be dissolved in the dye solution, a high water resistance of polyvinyl alcohol-iodine (I ₃₎ complex is selectively located in or discoloration to blue, skin The orientation of the oriented polyvinyl alcohol-based resin may be relaxed, and the polarization performance of the polarizing film may be deteriorated. The thickness (L) of the lamellar crystal is preferably 14.0 nm or more, and more preferably 15.5 nm or more.

If the thickness (L) of the lamellar crystal exceeds 45.0 nm, the dyeability may be deteriorated in the course of the production of the polarizing film in the subsequent step, thereby impairing the productivity. The thickness (L) of the lamellar crystal is more preferably 35.0 nm or less.

The thickness L of the lamellar crystal can be determined by introducing a monomer controlling the thickness L of the lamellar crystal as a constituent monomer (hereinafter also referred to as a " lamellar growth control monomer unit "), Can be adjusted by the position and the frequency of the light. The lamellar growth control monomer unit is preferably a monomer unit having at least a certain volume and having at least one substituent which tends to be difficult to exist in the crystal lattice of the lamellar crystal during crystallization due to steric hindrance. The lamellar growth control monomer unit having such a substituent has a higher probability of being present in the folded portion of the polymer chain constituting the folded structure. Therefore, the position and frequency of the lamellar growth control monomer unit in the polymer chain affects the thickness L of the lamellar crystal. The higher the frequency of such a lamellar growth controlling monomer unit is, the smaller the thickness L of the lamellar crystal of the polymer chain is.

It is preferable that the length of the substituent having a bulk bulk of at least a certain level in the lamellar growth controlling monomer unit is 3.0 Å or more. Normally, the bond between atoms is 1.2 to 1.6 ANGSTROM, so that the substituent having a length of 3.0 ANGSTROM or more will cause a failure of the folded structure and increase the possibility of being pushed out of the folded structure. For example, when the substituent is an n-propyl group, since the C-C bonds are three consecutive, the length is 4.5 Å, which is calculated from 1.5 Å, which is the standard length of the C-C bond. Therefore, it can be seen that it is suitable as a substituent having a bulk volume of a certain level or more.

The lamellar growth controlling monomer unit is represented by the following formula (1), which has one substituent having a bulk volume.

In the formula (1), the substituent X has a bulk volume equal to or greater than a certain value, and preferably has a length of 3.0 Å or more as described above. Such a substituent X is preferably one having two or more atoms other than hydrogen (H). When the number of atoms other than hydrogen (H) is less than 2, the bulk volume of the substituent X is not sufficient and the possibility of being pushed out of the folding structure of the lamellar type crystal is low. For example, when the substituent X is CH ₃ or H, even if such a unit is present singly or continuously in the polyvinyl alcohol, the folding structure of the lamellar crystal is not obstructed and the folded portion of the lamellar crystal is controlled There is no number. Further, when the substituent X is too large, it sometimes hinders the crystallization itself. Therefore, the number of atoms other than the hydrogen (H) contained in the substituent X is preferably 10 or less. Examples of the atoms other than hydrogen (H) include carbon (C), oxygen (O), chlorine (Cl), and the like.

Examples of the substituent X include an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a phenyl group, a benzyl group, an ethoxy group, a propoxy group and a butoxy group. The substituent X may contain an unsaturated bond such as C = C or C = O in addition to the saturated bond, and may be an allyl group, a propynyl group, a butenyl group, a butynyl group, or a butoxycarbonyl group. The substituent X may include a bond such as an ether bond, an ester bond, a urethane bond or the like in the chain, and may contain a hydroxy group or the like.

The lamellar growth control monomer unit is not limited to the one represented by the above formula (1), but may be one represented by the following formula (2) having two substituents.

In the general formula (2), the substituent X has a bulk volume equal to or greater than a certain value and is as described for the substituent X in the general formula (1). The substituent Y may or may not have a bulk volume above a certain level. When the substituent Y has a bulk volume equal to or greater than a certain level, the substituent X in the formula (1) is as described above. In this case, the substituent X may be the same or different.

On the other hand, the lamellar growth control monomer unit in the polymer chain controls the folding portion of the polymer chain and the vinyl alcohol monomer unit (the monomer which does not steric hindrance of the crystal lattice) continuous from the folded portion of the polymer chain to the next folded portion Unit may be included, and the same applies hereinafter). That is, since the adjustment of the position and the frequency of the lamellar growth-controlling monomer unit is reflected in the number of continuous vinyl alcohol monomer units in the polymer chain, the average value of the number of continuous vinyl alcohol monomer units in the polymer chain Average continuous unit number "). The larger the average value of the number of the continuous vinyl alcohol monomer units, the greater the thickness L of the lamellar type crystal.

As a method of adjusting the thickness (L) of a lamellar crystal of a polyvinyl alcohol-based resin in a stretched film, a method of adjusting the position and frequency of the lamellar growth-controlling monomer unit contained in the polyvinyl alcohol- The thickness L of the lamellar crystal can be adjusted without changing important physical properties such as the degree of polarization and the contractive force in the lamellar crystal.

On the other hand, as a method of adjusting the thickness (L) of the lamellar crystal of the polyvinyl alcohol-based resin in the stretched film, a method of adjusting the stretching magnification and the thermal history may be used. The higher the draw ratio, the greater the thickness L of the lamellar crystal. It is preferable that the stretching magnification is suitably adjusted within a range in which the polarization performance and the contracting force are not problematic. The adjustment of the thermal history is performed by, for example, adjusting the amount of heat applied during film-forming drying of the polyvinyl alcohol-based resin, that is, adjusting the temperature and time or adjusting the stretching temperature. On the other hand, the range of the thickness (L) of the lamellar crystal which can be adjusted by the thermal history is small as compared with the above-described method of adjusting the position and frequency of the lamellar growth control monomer unit. Therefore, as a method of adjusting the thickness (L) of the lamellar crystal, it is preferable to carry out the above-mentioned method for adjusting the position and frequency of the lamellar growth controlling monomer unit alone or in combination with other methods.

The thickness (L) of the lamellar crystal referred to in the present specification is determined by the thickness (L) obtained by the above formula (1) using the crystal melting peak temperature T (K) measured by differential scanning calorimetry (DSC) )to be. The differential calorimetry is performed by sweeping the temperature from 50 ° C to 250 ° C at a rate of 10 ° C / min using a differential calorimeter. Crystallization of the polyvinyl alcohol-based resin starts at a temperature exceeding 200 占 폚, and then a crystal melting peak appears. The temperature at the peak position of the crystal melting peak between 200 deg. C and 250 deg. C derived from the crystal is referred to as the crystal melting peak temperature T (K). As the differential calorimeter, "DSC6220" manufactured by Seiko Instruments Inc. may be mentioned.

The width X and the depth Y of the lamellar crystal 50 do not affect the thermodynamic stability itself of the lamellar crystal 50 but affect the crystal size and crystallinity, It affects the time required for the vinyl alcohol-based resin to dissolve. This is because the crystal size and the degree of crystallization have a correlation with the dissolution rate.

The width X and the depth Y of the lamellar-shaped crystal 50 can be adjusted, for example, by the thermal history of the polyvinyl alcohol-based resin. The adjustment of the thermal history is performed, for example, by adjusting the amount of heat applied during film-drying of the polyvinyl alcohol-based resin, that is, adjusting the temperature or time, or adjusting the stretching temperature. The crystallinity of the polyvinyl alcohol-based resin is preferably 15% or more, more preferably 20% or more, and still more preferably 25% or more, from the viewpoint of suppressing the dissolution rate. Therefore, it is preferable to select the thermal history in the polyvinyl alcohol-based resin so that the crystallinity becomes such that the width X and the depth Y of the lamellar crystal 50 are properly adjusted.

The polarizing film of the present invention is produced by using the stretched film described above and is obtained by dying the stretched film with a dichroic dye. By using the above-mentioned stretched film, dissolution of the polyvinyl alcohol-based resin into the dyeing aqueous solution is suppressed, so that a polarizing film having good appearance, excellent film strength, and excellent polarizing performance can be obtained. In addition, since the stretched film described above has good dyeability, high productivity can be maintained in the production process of the polarizing film.

The polarization performance of the polarizing film will be described in more detail. The polarization performance is generally evaluated by two parameters called " Visibility-corrected single-unit transmittance Ty " and " Visibility- These parameters are the transmittance and the degree of polarization in the visible region (wavelength 380 to 780 nm) corrected to maximize the weight at about 550 nm, which is the highest sensitivity of the human eye. Since light with a wavelength of less than 380 nm can not be seen by the human eye, Ty and Py are not considered.

Visual Sensitivity Correction of Polarizing Film The single light transmittance Ty may be a value usually required in an image display apparatus such as a liquid crystal display or the like to which a polarizing film or a polarizing plate including the polarizing film is applied. Specifically, the transmittance Ty may be within a range of 40 to 47% . Ty is more preferably in the range of 41 to 45%, and in this case, the balance between Ty and Py becomes better. If Ty is too high, Py is lowered and the display quality of the image display device is lowered. If Ty is excessively low, the luminance of the image display apparatus is lowered and the display quality is lowered, or the input power must be increased in order to sufficiently increase the luminance. The visual sensitivity correction degree Py of the polarizing film is preferably 99.9% or more, and more preferably 99.95% or more.

The thickness of the polarizing film may be, for example, 30 占 퐉 or less, more preferably 20 占 퐉 or less, but is preferably 10 占 퐉 or less and more preferably 8 占 퐉 or less from the viewpoint of thinning of the polarizing plate. The thickness of the polarizing film is usually 2 占 퐉 or more.

The polarizing film preferably has a piercing strength per unit thickness of 6.0 g / m or more. If the piercing strength is 6.0 g / 탆 or more, the rate of occurrence of cracking of the polarizing film in the durability test such as the heat shock test can be remarkably suppressed.

(1) Layer structure of polarizer

2 is a schematic cross-sectional view showing an example of the layer structure of the polarizing plate according to the present invention. Like the polarizing plate 1 shown in Fig. 2, the polarizing plate of the present invention can be a polarizing plate with a single-sided protective film having a polarizing film 5 and a first protective film 10 laminated on one side thereof . The first protective film 10 may be laminated on the polarizing film 5 through the first adhesive layer 15. [

The polarizing plate according to the present invention may be obtained by further bonding a protective film to the other surface of the polarizing film 5. Specifically, as in the polarizing plate 2 shown in Fig. 3, , A first protective film (10) laminated on one side thereof, and a second protective film (20) laminated on the other side. The second protective film 20 can be laminated on the polarizing film 5 through the second adhesive layer 25. [

The polarizing plate according to the present invention may be a polarizing plate disposed on the visual (front) side of an image display device such as a liquid crystal cell when included in an image display device such as a liquid crystal display device, The backlight side of the polarizing plate).

(2) polarizing film

The polarizing plate according to the present invention includes, as the polarizing film 5, the polarizing film according to the present invention described above. Therefore, the details of the polarizing film 5 are cited above.

(3) The first protective film

The first protective film 10 is preferably made of a thermoplastic resin having translucency (preferably optically transparent) such as a chain polyolefin resin (polypropylene resin), a cyclic polyolefin resin (norbornene resin, etc.) Polyolefin resin; Cellulose ester-based resins such as cellulose triacetate and cellulose diacetate; Polyester-based resin; Polycarbonate resin; (Meth) acrylic resins; Polystyrene type resin; Or a mixture or copolymer thereof, or the like.

The first protective film 10 may be a protective film having optical functions such as a retardation film and a brightness enhancement film. For example, a retardation film having an arbitrary retardation value can be obtained by stretching (uniaxially stretching or biaxially stretching) the film made of the thermoplastic resin, or forming a liquid crystal layer or the like on the film.

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.

The cyclic polyolefin-based resin is a generic name of a resin that is polymerized using a cyclic olefin as a polymerization unit. Specific examples of the cyclic polyolefin-based resin include ring-opened (co) polymers of cyclic olefins, addition polymers of cyclic olefins, copolymers (typically, random copolymers) of cyclic olefins and chain olefins such as ethylene and propylene, Graft polymers modified with carboxylic acids and derivatives thereof, and hydrides thereof. Among them, a norbornene resin using a norbornene monomer such as norbornene or a polycyclic norbornene monomer as the cyclic olefin is preferably used.

The cellulose ester resin is an ester of cellulose and a fatty acid. Specific examples of the cellulose ester-based resin include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. Further, copolymers of these and those obtained by modifying a part of hydroxyl groups with other substituents may be used. Of these, cellulose triacetate (triacetylcellulose: TAC) is particularly preferable.

The polyester-based resin is a resin other than the above-mentioned cellulose ester-based resin having an ester bond, and is generally composed of a polycondensation product of a polyvalent carboxylic acid or a derivative thereof and a polyhydric alcohol. As the polycarboxylic acid or its derivative, a dicarboxylic acid or a derivative thereof can be used, and examples thereof include terephthalic acid, isophthalic acid, dimethylterephthalate, and dimethyl naphthalenedicarboxylate. Examples of polyhydric alcohols include diols such as ethylene glycol, propanediol, butanediol, neopentyl glycol, and cyclohexanedimethanol.

Specific examples of the polyester-based resin include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polytrimethylene terephthalate, polytrimethylene naphthalate, polycyclohexanedimethyl terephthalate, polycyclohexane Dimethyl naphthalate.

The polycarbonate resin is composed of a polymer to which a monomer unit is bonded through a carbonate group. The polycarbonate resin may be a resin such as a modified polycarbonate having modified polymer skeleton, a copolymerized polycarbonate, or the like.

The (meth) acrylic resin is a resin mainly composed of a compound having a (meth) acryloyl group. Specific examples of the (meth) acrylic resin include 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 acid ester- (meth) acrylic acid copolymer; (Meth) acrylate-styrene copolymer (MS resin and the like); A copolymer of methyl methacrylate and a compound having an alicyclic hydrocarbon group (e.g., methyl methacrylate-cyclohexyl methacrylate copolymer, methyl methacrylate- (meth) acrylate norbornyl copolymer, etc.) . Preferably, the poly (meth) poly (meth) acrylic acid C _1, such as methyl _{acrylate-polymer} to the _6-alkyl ester as a main component is used, more preferably, the methyl methacrylate and the main component (50 to 100% by weight, By weight, preferably 70 to 100% by weight) is used.

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 may be formed on the surface of the first protective film 10 opposite to the polarizing film 5. The first protective film 10 may contain one or more additives such as a lubricant, a plasticizer, a dispersant, a heat stabilizer, an ultraviolet absorber, an infrared absorber, an antistatic agent and an antioxidant.

The thickness of the first protective film 10 is preferably 90 占 퐉 or less, more preferably 50 占 퐉 or less, still more preferably 30 占 퐉 or less, from the viewpoint of thinning of the polarizing plate. The thickness of the first protective film 10 is usually 5 占 퐉 or more from the viewpoints of strength and handleability.

(4) First adhesive layer

The first adhesive layer 15 is a layer for adhering and fixing the first protective film 10 to one surface of the polarizing film 5. The adhesive forming the first adhesive layer 15 may be an active energy ray-curable adhesive containing a curable compound which is cured by irradiation with an active energy ray such as ultraviolet rays, visible light, electron beams or X-rays or an adhesive such as a polyvinyl alcohol- Based adhesive in which the component is dissolved or dispersed in water.

As the active energy ray-curable adhesive forming the first adhesive layer 15, since it exhibits good adhesiveness, an active energy ray-curable adhesive composition comprising a cationically polymerizable curable compound and / or a radically polymerizable curable compound is preferably used . The active energy ray curable adhesive may further comprise a cation polymerization initiator and / or a radical polymerization initiator for initiating the curing reaction of the curable compound.

Examples of the cationically polymerizable curable compound include epoxy compounds (compounds having one or two or more epoxy groups in the molecule), oxetane compounds (compounds having one or two or more oxetane rings in the molecule) Combinations. Examples of the radically polymerizable curable compound include (meth) acrylic compounds (compounds having one or more (meth) acryloyloxy groups in the molecule), other vinyl compounds having a radically polymerizable double bond, or And combinations thereof. A cationically polymerizable curable compound and a radical polymerizable curable compound may be used in combination.

The active energy ray-curable adhesive can be cured, if necessary, by a cationic polymerization accelerator, an ion trap agent, an antioxidant, a chain transfer agent, a tackifier, a thermoplastic resin, a filler, a flow regulator, a plasticizer, a defoamer, an antistatic agent, May contain additives.

The thickness of the first adhesive layer 15 is usually about 0.001 to 5 mu m, preferably 0.01 to 3 mu m.

(5) Second protective film

The second protective film 20 of the polarizing plate 2 with a double-sided protective film shown in Fig. 3 may be a film made of the thermoplastic resin exemplified above as in the case of the first protective film 10, Or a protective film having an optical function such as an enhancement film. With respect to the surface treatment layer and the thickness of the film that the second protective film 20 can have, the above description relating to the first protective film 10 is cited. The first protective film 10 and the second protective film 20 may be protective films made of the same kind of resin or protective films made of different kinds of resins.

(6) Second adhesive layer

The second adhesive layer 25 is a layer for adhering and fixing the second protective film 20 to the other surface of the polarizing film 5. With respect to the details of the second adhesive layer 25, reference is made to the description of the first adhesive layer 15 described above. The adhesive forming the second adhesive layer (25) may have the same composition as the adhesive forming the first adhesive layer (15) or may have another composition.

(7) Pressure-sensitive adhesive layer

The first protective film 10 or the second protective film 10 on the polarizing film 5 of the polarizing plate 1 with a one-sided protective film shown in Fig. 2 or the polarizing plate 2 with the two- A pressure-sensitive adhesive layer for bonding the polarizing plate to another member (for example, a liquid crystal cell in the case of application to a liquid crystal display) may be laminated on the protective film 20. The pressure-sensitive adhesive for forming the pressure-sensitive adhesive layer is usually composed of a pressure-sensitive adhesive composition comprising a base polymer and a crosslinking agent such as an isocyanate compound, an epoxy compound and an aziridine compound added thereto, typically a (meth) acrylic resin, a styrene resin or a silicone resin. Further, a pressure-sensitive adhesive layer containing fine particles and exhibiting light scattering properties may be used. The thickness of the pressure-sensitive adhesive layer is usually 1 to 40 占 퐉, preferably 3 to 25 占 퐉.

(8) Other optical layers

The polarizing plate according to the present invention may further include another optical layer laminated on the first and / or second protective films 10 and 20 or the polarizing film 5. As another optical layer, a reflective polarizing film that transmits polarized light of a certain kind and reflects polarized light exhibiting properties opposite to that of the polarized light; A film having an antireflection function on the surface; A film having surface antireflection function; A reflecting film having a reflecting function on the surface; A transflective film having a reflection function and a transmission function; And a viewing angle compensation film.

&Lt; Stretched film, polarizing film and method for producing polarizing plate >

The stretched film, polarizing film and polarizing plate of the present invention can be suitably produced by the method shown in Fig. The manufacturing method shown in Fig. 4 comprises the following steps:

(1) a resin layer forming step S10 for forming a polyvinyl alcohol-based resin layer by coating a coating solution containing a polyvinyl alcohol-based resin on at least one surface of a base film and then drying,

(2) a stretching step S20 for obtaining a stretched laminated film having a stretched film which is a polyvinyl alcohol-based resin layer stretched on a base film by stretching the laminated film,

(3) a dyeing step S30 for obtaining a polarizing laminated film by forming a polarizing film (polarizer layer) by dyeing the drawn film of the drawn laminated film with iodine,

(4) a first bonding step S40 of bonding a protective film to the polarizing film of the polarizing laminated film to obtain a bonded film,

(5) a peeling step S50 for peeling off the base film from the bonding film to obtain a polarizing plate with one side protective film

In this order.

In the case of producing the polarizing plate 2 with a double-sided protective film as shown in Fig. 3, after the peeling step S50,

(6) A second bonding step S60 for bonding a protective film to the polarizing film side of the polarizing plate with one side protective film

.

Hereinafter, each step will be described with reference to Figs. 5 to 8. Fig. On the other hand, in the resin layer forming step S10, the polyvinyl alcohol-based resin layer may be formed on both surfaces of the base film. Hereinafter, a case where the polyvinyl alcohol-based resin layer is mainly formed on one surface will be described.

(1) Resin layer formation step S10

5, the present step is a step of forming a polyvinyl alcohol-based resin layer 6 on at least one surface of a base film 30 to obtain a laminated film 100. This polyvinyl alcohol-based resin layer 6 is a layer which becomes a stretched film 6 'through a stretching step S20 and becomes a polarizing film 5 through a dyeing step S30. The polyvinyl alcohol-based resin layer 6 can be formed by coating a coating liquid containing a polyvinyl alcohol-based resin on one side or both sides of the base film 30 and drying the coating layer. The method of forming the polyvinyl alcohol-based resin layer by such coating is advantageous in that it is easy to obtain a polarizing film 5 of a thin film.

The base film 30 may be composed of a thermoplastic resin, and it is preferable that the base film 30 is made of a thermoplastic resin having excellent transparency, mechanical strength, thermal stability, stretchability and the like. Specific examples of such a thermoplastic resin include polyolefin resins such as a chain polyolefin resin and a cyclic polyolefin resin (norbornene resin and the like); Polyester-based resin; (Meth) acrylic resins; Cellulose ester-based resins such as cellulose triacetate and cellulose diacetate; Polycarbonate resin; Polyvinyl alcohol-based resin; Polyvinyl acetate resin; Polyarylate resins; Polystyrene type resin; Polyether sulfone type resin; Polysulfone resins; Polyamide based resin; Polyimide resin; And mixtures and copolymers thereof.

The base film 30 may have a single-layer structure composed of one resin layer made of one kind or two or more kinds of thermoplastic resins, or a multilayer structure in which a plurality of resin layers made of one kind or two or more kinds of thermoplastic resins are laminated. The base film 30 is preferably composed of a resin that can be stretched at a drawing temperature suitable for drawing the polyvinyl alcohol-based resin layer 6 when the laminated film 100 is stretched in a stretching step S20 described later Do.

The base film 30 may contain an additive. Specific examples of the additives include an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a release agent, a coloring inhibitor, a flame retardant, a nucleating agent, an antistatic agent, a pigment and a colorant.

The thickness of the base film 30 is usually 1 to 500 탆, preferably 1 to 300 탆, more preferably 5 to 200 탆, and still more preferably 5 to 150 탆, from the viewpoints of strength and handling properties.

The coating liquid applied to the base film 30 is preferably a polyvinyl alcohol-based resin solution obtained by dissolving a polyvinyl alcohol-based resin powder in a good solvent (for example, water). Details of the polyvinyl alcohol-based resin are as described above. The coating liquid may contain an additive such as a plasticizer and a surfactant if necessary.

The method of applying the coating solution to the base film (30) may be a wire bar coating method; Roll coating methods such as reverse coating and gravure coating; Die coating method; Comma coat method; Lip coating method; Spin coating method; Screen coating method; Fountain coating method; Dipping method; Spray method, and the like.

The drying temperature and drying time of the coating layer (polyvinyl alcohol-based resin layer before drying) are set according to the type of the solvent contained in the coating liquid. The drying temperature is, for example, 50 to 200 ° C, preferably 60 to 150 ° C. When the solvent includes water, the drying temperature is preferably 80 DEG C or higher.

The polyvinyl alcohol-based resin layer 6 may be formed on only one side of the base film 30 or on both sides thereof. It is possible to suppress the curling of the film which may occur in the production of the polarizing laminated film 300 (see Fig. 7), and to obtain two polarizing plates from one polarizing laminated film 300 It is advantageous in terms of production efficiency of the polarizing plate.

The thickness of the polyvinyl alcohol-based resin layer 6 in the laminated film 100 is preferably 3 to 30 占 퐉, more preferably 5 to 20 占 퐉. If the polyvinyl alcohol-based resin layer 6 having a thickness within this range is used, it can be passed through a stretching step S20 and a dyeing step S30, which will be described later, so that the dyeability of iodine is good, ) Polarizing film 5 can be obtained.

In order to improve adhesion between the base film 30 and the polyvinyl alcohol-based resin layer 6 prior to coating of the coating liquid, at least the base film 30 on which the polyvinyl alcohol-based resin layer 6 is formed, A corona treatment, a plasma treatment, a frame (flame) treatment, or the like may be performed on the surface of the substrate. For the same reason, the polyvinyl alcohol-based resin layer 6 may be formed on the base film 30 through a primer layer or the like.

The primer layer can be formed by coating a coating solution for forming a primer layer on the surface of the base film 30 and then drying it. This coating liquid contains a component exhibiting a strong adhesion to some extent to both the base film 30 and the polyvinyl alcohol-based resin layer 6, and usually includes a resin component and a solvent that impart such adhesion . As the resin component, a thermoplastic resin having excellent transparency, thermal stability and stretchability is preferably used, and examples thereof include (meth) acrylic resin, polyvinyl alcohol resin and the like. Among them, a polyvinyl alcohol-based resin which gives good adhesion is preferably used. More preferably, it is a polyvinyl alcohol resin. As a solvent, a general organic solvent or an aqueous solvent capable of dissolving the resin component is usually used, but it is preferable to form a primer layer from a coating solution containing water as a solvent.

In order to increase the strength of the primer layer, a crosslinking agent may be added to the coating solution for forming a primer layer. Specific examples of the crosslinking agent include epoxy-based, isocyanate-based, dialdehyde-based, metal-based (for example, metal salts, metal oxides, metal hydroxides, organometallic compounds) and high molecular weight crosslinking agents. When a polyvinyl alcohol-based resin is used as the resin component forming the primer layer, a polyamide epoxy resin, a methylol melamine resin, a dialdehyde-based cross-linking agent, a metal chelate-based cross-linking agent and the like are suitably used.

The thickness of the primer layer is preferably about 0.05 to 1 mu m, more preferably 0.1 to 0.4 mu m. If the thickness is smaller than 0.05 탆, the effect of improving adhesion between the base film 30 and the polyvinyl alcohol-based resin layer 6 is small, and if it is thicker than 1 탆, it is disadvantageous for making the polarizing plate thinner.

The method of coating the primer layer-forming coating solution on the base film 30 may be the same as the coating solution for forming the polyvinyl alcohol-based resin layer. The drying temperature of the coating layer composed of the coating solution for forming a primer layer is, for example, 50 to 200 ° C, preferably 60 to 150 ° C. When the solvent includes water, the drying temperature is preferably 80 DEG C or higher.

(2) Drawing process S20

6, the present step is a step of stretching a laminated film 100 made of a base film 30 and a polyvinyl alcohol-based resin layer 6 and forming a stretched poly Is a step of obtaining a stretched laminated film 200 having a stretched film 6 'which is a vinyl alcohol-based resin layer. The stretching treatment is usually uniaxial stretching.

The stretching magnification of the laminated film 100 can be appropriately selected in accordance with the desired polarization characteristics and the thickness L of the lamellar crystal. It is preferably 1.1 to 17 times, more preferably 1.5 to 8 times the original length of the laminated film 100. If the stretching magnification exceeds 17 times, the film tends to be broken at the time of stretching, and the thickness of the stretched laminated film 200 becomes thinner than necessary, which may lower the workability and handleability in subsequent steps.

The stretching treatment is not limited to stretching in one stage but may be performed in multiple stages. In this case, all of the multi-stage drawing process may be performed continuously before the dyeing process S30, and the drawing process after the second step may be performed simultaneously with the dyeing process and / or the crosslinking process in the dyeing process S30. In such a multi-stage drawing process, it is preferable to perform the drawing process so that the entire stages of the drawing process are combined so as to have a drawing magnification of more than four times.

The stretching treatment may be longitudinal stretching in which stretching is performed in the longitudinal direction of the film (film transport direction), transverse stretching or oblique stretching in stretching in the film width direction, or the like. Examples of the longitudinal stretching method include roll-to-roll stretching using a roll, compression stretching, and stretching using a chuck. The transverse stretching method includes a tenter method and the like. Any of the wet drawing method and the dry drawing method can be employed for the drawing treatment, but a dry drawing method is preferable because the drawing temperature can be selected in a wide range.

The stretching temperature is set to a temperature higher than the temperature at which the entirety of the polyvinyl alcohol resin layer 6 and the substrate film 30 can be stretched to exhibit fluidity and is preferably set at a temperature higher than the phase transition temperature (melting point or glass transition temperature ) To -30 deg. C, more preferably -30 deg. C to +5 deg. C, and still more preferably -25 deg. C to +0 deg. When the base film 30 is composed of a plurality of resin layers, the phase transition temperature means the highest phase transition temperature among the phase transition temperatures indicated by the plurality of resin layers.

If the stretching temperature is lower than -30 占 폚 of the phase transition temperature, high-magnification stretching exceeding 4 times is not easily attained, or the fluidity of the base film 30 is too low to make the stretching process difficult. If the stretching temperature exceeds + 30 ° C of the phase transition temperature, the fluidity of the base film 30 is too large, and the stretching tends to be difficult. The stretching temperature is within the above range, more preferably 120 deg. C or more, since it is easier to achieve a high draw ratio of more than 4 times.

Examples of the heating method of the laminated film 100 in the stretching treatment include a zone heating method (for example, heating in a stretching zone such as a heating furnace blowing hot air and adjusting the temperature to a predetermined temperature); A method of heating the roll itself in the case of stretching using a roll; A heater heating method (a method in which an infrared heater, a halogen heater, a panel heater, or the like is installed on the top and bottom of the laminated film 100 and heated by radiant heat). In the roll-to-roll stretching method, the zone heating method is preferable from the viewpoint of the uniformity of the stretching temperature.

On the other hand, in the case of the zone heating method, the stretching temperature means the atmospheric temperature inside the zone (for example, inside the heating furnace), and the heating temperature means the atmospheric temperature inside the furnace when heating is performed inside the furnace. In the case of the method of heating the roll itself, it means the surface temperature of the roll.

Prior to the stretching step S20, a preheating treatment step for preheating the laminated film 100 may be provided. As the preheating method, the same method as the heating method in the stretching treatment can be used. The preheating temperature is preferably in the range of -50 占 폚 to 占 0 占 폚 of the stretching temperature, and more preferably in the range of -40 占 폚 to -10 占 폚 of the stretching temperature.

After the stretching process in the stretching process S20, a heat fixing process may be performed. The heat setting process is a process of performing heat treatment at a crystallization temperature or higher, while keeping the end portion of the oriented laminated film 200 in a state of being held in a state of being held by a clip. By this heat setting treatment, the crystallization of the stretched film 6 'is promoted. The heat-setting treatment temperature is preferably in the range of -0 to -80 占 폚 of the stretching temperature, and more preferably in the range of -0 to -50 占 폚 of the stretching temperature.

(3) Dyeing process S30

Referring to Fig. 7, the present step is a step of dying the stretched film 6 'of the stretched laminated film 200 with iodine and adsorbing the stretched film 6' to obtain a polarizing film 5. The polarizing laminated film 300 in which the polarizing film 5 is laminated on one side or both sides of the base film 30 'through this step can be obtained.

The dyeing step can be carried out by immersing the entire stretched laminated film 200 in a solution (aqueous dyeing solution) containing iodine. As the dyeing aqueous solution, a solution in which iodine is dissolved in a solvent can be used. As the solvent, water is generally used, but an organic solvent having compatibility with water may be further added. The concentration of iodine in the dyeing aqueous solution is preferably 0.01 to 10% by weight, and more preferably 0.02 to 7% by weight.

It is preferable to add iodide to the dyeing aqueous solution. Examples of the iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide and titanium iodide. The concentration of iodide in the dyeing aqueous solution is preferably 0.01 to 20% by weight. It is preferable to add potassium iodide even in iodide. When potassium iodide is added, the weight ratio of iodine to potassium iodide is preferably 1: 5 to 1: 100, more preferably 1: 6 to 1:80. The temperature of the dyeing aqueous solution is preferably from 10 to 60 캜, more preferably from 20 to 40 캜.

The dyeing step S30 may include a crosslinking treatment step which is carried out subsequent to the dyeing treatment. The crosslinking treatment can be carried out by immersing the dyed film in a solution (crosslinking solution) in which the crosslinking agent is dissolved in a solvent. Examples of the crosslinking agent include boron compounds such as boric acid and borax, glyoxal, and glutaraldehyde. The crosslinking agent may be used alone or in combination of two or more. As the solvent for the crosslinking solution, water may be used, but an organic solvent which is compatible with water may be further contained. The concentration of the crosslinking agent in the crosslinking solution is preferably 0.2 to 20% by weight, and more preferably 0.5 to 10% by weight.

The crosslinking solution may further contain iodide. By adding iodide, the polarization performance in the plane of the polarizing film 5 can be made more uniform. Specific examples of the iodide are the same as described above. The concentration of iodide in the crosslinking solution is preferably 0.05 to 15% by weight, more preferably 0.5 to 8% by weight. The temperature of the crosslinking solution is preferably 1 to 90 占 폚.

On the other hand, the crosslinking treatment may be carried out simultaneously with the dyeing treatment by blending the crosslinking agent into the dyeing aqueous solution. The treatment of immersing in a crosslinking solution may be carried out two or more times using two or more crosslinking solutions having different compositions.

After the dyeing step S30, it is preferable to carry out a washing step and a drying step before the first joining step S40 to be described later. The cleaning process usually includes a water cleaning process. The water washing treatment can be performed by immersing the film after the dyeing treatment or after the crosslinking treatment in pure water such as ion-exchanged water or distilled water. The water washing temperature is usually from 3 to 50 캜, preferably from 4 to 20 캜. The cleaning step may be a combination of a water cleaning step and a cleaning step with an iodide solution. As the drying step performed after the cleaning step, any suitable method such as natural drying, air blow drying, and heat drying can be employed. For example, in the case of heat drying, the drying temperature is usually 20 to 95 ° C.

(4) First bonding step S40

8, this step is carried out in such a manner that an adhesive layer is formed on the polarizing film 5 of the polarizing laminated film 300, that is, the surface of the polarizing film 5 opposite to the base film 30 ' And then a protective film is bonded to obtain a bonding film 400. [ 8 shows an example of bonding the first protective film 10 through the first adhesive layer 15. In the case of producing the polarizing plate 2 with a double-sided protective film, the second adhesive layer 25 The second protective film 20 may be bonded to the second protective film 20 via the second protective film 20. The adhesive forming the first adhesive layer 15 or the second adhesive layer 25 is the same as described above.

On the other hand, when the polarizing laminated film 300 has the polarizing films 5 on both sides of the base film 30 ', the protective films are usually bonded onto the polarizing films 5 on both sides. In this case, these protective films may be the same kind of protective film or different kinds of protective films.

As an example of bonding the first protective film 10 using an active energy ray-curable adhesive, a method of bonding and bonding the protective film will be described below. After the first protective film 10 is laminated on the polarizing film 5, active energy rays such as ultraviolet rays, visible light, electron beams and X-rays are irradiated to cure the adhesive layer. Among them, ultraviolet rays are suitable. As the light source in this case, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultra high pressure mercury lamp, a chemical lamp, a black light lamp, a microwave excited mercury lamp, a metal halide lamp and the like can be used.

The bonding surface of the protective film and / or the polarizing film 5 may be subjected to a plasma treatment, a corona treatment, an ultraviolet ray irradiation (ultraviolet ray irradiation) or the like in order to improve the adhesiveness with the polarizing film 5, (Flame) treatment, a saponification treatment, and the like. Among them, plasma treatment, corona treatment or saponification treatment is preferably carried out.

(5) Peeling step S50

This step is a step of peeling off the base film 30 'from the bonding film 400. Through this process, a polarizing plate with a single-sided protective film as shown in Fig. 2 can be obtained. When the polarizing laminated film 300 has the polarizing film 5 on both sides of the base film 30 'and the protective film is bonded to both of the polarizing films 5, Two polarizing plates with a single-sided protective film can be obtained from the polarizing laminated film 300 of the sheet.

The method of peeling off the base film 30 'is not particularly limited, and can be peeled off in the same manner as the peeling process of a separator (peeling film) which is performed in a usual polarizing plate with a pressure-sensitive adhesive. The base film 30 'may be immediately peeled as it is after the first bonding step S40, or it may be peeled off while being rolled once in the form of a roll after the first bonding step S40.

(6) Second bonding step S60

In this step, a protective film is further bonded on the polarizing film 5 of the polarizing plate with one-side protective film, that is, on the side opposite to the protective film bonded in the first joining step S40, Is a step of obtaining a polarizing plate (2) with a protective film. In the case where the first protective film 10 is bonded in the first bonding step S40, when the second protective film 20 is bonded in this step and the second protective film 20 is bonded in the first bonding step S40 , The first protective film 10 is bonded in this step. The bonding of the second protective film 20 through the second adhesive layer 25 can be performed in the same manner as the bonding of the first protective film 10.

The method of forming the polarizing film from the polyvinyl alcohol-based resin layer coated on the base film and then producing the polarizing plate has been described in detail. However, the present invention is not limited to this, but a polarizing film (single film) 5 may be bonded to the first protective film 10 or the first and second protective films 10, 20 to produce a polarizing plate.

The stretched film 6 'and the polarizing film 5 made of a single (single) film can be produced by the steps of: preparing a polyvinyl alcohol based resin film by a known method such as melt extrusion or solvent casting; Uniaxially stretching the polyvinyl alcohol-based resin film to obtain a stretched film 6 '; Dyeing the stretched film with iodine, and adsorbing it; Treating the stretched film with iodine adsorption with an aqueous solution of boric acid; And water after treatment with an aqueous boric acid solution to obtain a polarizing film (5). Uniaxial stretching can be carried out before, after or simultaneously with dyeing of iodine. In the case of uniaxial stretching after dyeing, the uniaxial stretching may be carried out before the boric acid treatment or during the boric acid treatment. In addition, uniaxial stretching may be performed at a plurality of these steps.

In the case of producing a polarizing plate with a double-sided protective film by bonding both of the first and second protective films 10 and 20, these protective films may be sequentially bonded through an adhesive layer or may be bonded at the same time.

(7) Adjustment of the thickness (L) of the lamellar crystal of the polyvinyl alcohol-based resin in the stretched film

The method of setting the thickness (L) of the lamellar crystal of the polyvinyl alcohol-based resin in the stretched film within the above-mentioned predetermined range is not particularly limited. However, as described above, a method of adjusting the position and frequency of the lamellar growth- Based resin is preferably adopted. The degree of adjustment of the position and frequency of the lamellar growth control monomer unit in the polyvinyl alcohol-based resin can be confirmed by the average value of the number of continuous vinyl alcohol monomer units in the polyvinyl alcohol-based resin.

The thickness (L) of the lamellar crystal of the polyvinyl alcohol-based resin in the stretched film can be adjusted within the above-mentioned predetermined range by adjusting the stretching magnification, thermal history, etc. of the polyvinyl alcohol-based resin layer in combination with, can do.

Example

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples.

&Lt; Example 1 >

(1) Primer layer formation process

Polyvinyl alcohol powder ("Z-200" manufactured by Nippon Gosei Chemical Industry Co., Ltd., average polymerization degree: 1100, saponification degree: 99.5 mol%) was dissolved in hot water at 95 ° C to prepare a polyvinyl alcohol aqueous solution having a concentration of 3% It was prepared. The obtained aqueous solution was mixed with 5 parts by weight of a crosslinking agent ("Sumirez Resin 650" manufactured by Daoka Kagaku Kogyo Co., Ltd.) per 6 parts by weight of the polyvinyl alcohol powder to obtain a coating solution for forming a primer layer.

Subsequently, an unoriented polypropylene (PP) film (melting point: 163 DEG C) having a thickness of 90 mu m was prepared as the base film, corona treatment was performed on one side thereof, and the primer And a primer layer having a thickness of 0.2 占 퐉 was formed by drying the coating solution for layer formation at 80 占 폚 for 10 minutes.

(2) Production of laminated film (resin layer forming step)

A polyvinyl alcohol resin powder having an average number of continuous units of 30 was dissolved in hot water at 95 캜 to prepare a polyvinyl alcohol aqueous solution having a concentration of 7.5% by weight and used as a coating liquid for forming a polyvinyl alcohol-based resin layer.

The coating solution for forming a polyvinyl alcohol-based resin layer was coated on the surface of the primer layer of the base film having the primer layer prepared in the above (1) using a die coater, followed by drying while spraying hot air at 70 캜 , And a polyvinyl alcohol-based resin layer was formed on the primer layer to obtain a laminated film comprising a base film / primer layer / polyvinyl alcohol-based resin layer. The thickness of the polyvinyl alcohol-based resin layer after drying was 9.2 占 퐉.

(3) Production of stretched laminated film (stretching process)

The laminated film prepared in (2) above was subjected to free uniaxial stretching at a maximum temperature of 150 DEG C at a maximum temperature of 500 DEG C during air drawing using a transverse uniaxial stretching apparatus (pneumatic stretching) To obtain a stretched laminated film provided with a stretched film made of a polyvinyl alcohol-based resin. The thickness of the stretched film made of the polyvinyl alcohol-based resin after stretching was 5.1 占 퐉.

(4) Production of a polarizing laminated film (dyeing process)

The stretched laminated film prepared in (3) above was immersed in a dyeing aqueous solution containing iodine and potassium iodide at 30 DEG C (containing iodine 0.35 parts by weight (iodine concentration 13.8 mM) and potassium iodide 10.0 parts by weight per 100 parts by weight of water) , The immersion time was appropriately adjusted so that the visually-sensitivity-corrected single-beam transmittance (Ty) measured in the later evaluation was 41.5%, and the stretched film was subjected to dyeing treatment, and then the excess dyeing solution was washed away with pure water at 10 占 폚. Table 1 shows the dyeing time in the dyeing aqueous solution.

Subsequently, the first crosslinked aqueous solution (containing 10.4 parts by weight of boric acid per 100 parts by weight of water) containing boric acid was immersed for 120 seconds at 78 DEG C, and then a second crosslinked aqueous solution (at 70 DEG C) containing boric acid and potassium iodide 5.0 parts by weight of boric acid and 12.0 parts by weight of potassium iodide per 100 parts by weight of water) for 60 seconds and further immersed in pure water at 10 DEG C for about 10 seconds to carry out crosslinking treatment. Thereafter, the liquid attached to both surfaces was immediately removed using an air blower to obtain a polarizing laminated film including a polarizing film.

(5) Fabrication of Polarizer with One Side Protective Film (First Bonding Step, Peeling Step)

A protective film (triacetylcellulose (TAC)) was applied to the polarizing film of the polarizing laminated film prepared in (4) above through an adhesive layer made of an ultraviolet curable adhesive (KR-75T manufactured by ADEKA) ("KC-2 UAW" manufactured by Konica Minolta Opt Co., Ltd.)) was bonded. Subsequently, the adhesive layer was cured by irradiating ultraviolet rays using a high-pressure mercury lamp to obtain a bonded film comprising a layer structure of a protective film / adhesive layer / polarizing film / base film (first bonding step). Thereafter, the base film was peeled off from the obtained bonding film to obtain a polarizing plate with a one side protective film (peeling step).

&Lt; Examples 2 to 13 and Comparative Examples 1 to 5 >

In Examples 2 to 13, the polyvinyl alcohol resin powder having the average number of continuous units shown in Table 1 was used as the polyvinyl alcohol-based resin powder used in (2) in Example 1, (4) in Examples 10 to 13 and Comparative Examples 3 to 5, in which the temperature at the time of stretching is set to the temperature shown in Table 1, the stretching magnification in the above-mentioned (3) Except that free-end uniaxial stretching of 3.0 times or 1.1 times of free-end uniaxial stretching was carried out in the first crosslinked aqueous solution of Example 1. When the stretching magnification in the first crosslinking aqueous solution shown in Table 1 is "1.0 times", it means that stretching in the first crosslinking aqueous solution is not performed.

[Calculation of thickness (L) of lamellar type crystal]

The base film was peeled off from the stretched laminated film obtained in the above (3), and the stretched film was taken out. After adjusting the humidity for 1 day under the environment of 23 ° C and 55% RH, 5 mg was filled in the measuring aluminum pan, . As a reference, an empty aluminum pan was sealed. With respect to the sample for evaluation and the reference, the calorie absorbed was measured while sweeping the temperature from 50 ° C to 250 ° C at 10 ° C / min using a differential scanning calorimeter (product name: DSC6220, manufactured by Seiko Instruments Inc.) . The thickness (L) of the lamellar crystal was calculated from the formula (1) by setting the peak melting point peak temperature T (K) at a peak position of the crystal melting peak between 200 deg. C and 250 deg. The results are shown in Table 1.

[Evaluation of dyeability]

The case in which the dyeing time was within 300 seconds was referred to as "good" and the case in which the dyeing time exceeded 300 seconds in accordance with the immersion time (dyeing time) in the dyeing aqueous solution (iodine concentration of 13.8 mM) Defective ". The results are shown in Table 1.

The reason for setting the dyeability evaluation standard to 300 seconds is that the line speed at which a certain level of productivity can be obtained is 10 m / min or more. In this case, in order to secure a dyeing residence time exceeding 300 seconds, This is because productivity is deteriorated. When a crosslinking tank, a sub-coloring tank or the like is provided after dyeing, the line retention length becomes longer. When the dyeing time is, for example, 100 seconds, the line retention length can be set to 20 m or less, so that it can be sufficiently performed by a general dyeing facility.

On the other hand, it is possible to shorten the residence time by increasing the iodine concentration of the dyeing aqueous solution. However, since iodine at a high concentration causes erosion of the equipment, it is difficult to continuously produce the dyeing aqueous solution with an iodine concentration of 20.0 mM or more for a long period of time. In addition, if the iodine concentration of the dyeing aqueous solution is high, not only the corrosion by the dyeing aqueous solution but also the corrosion outside the dyeing bath by the iodine vapor sublimated from the dyeing aqueous solution may be caused. Therefore, the iodine concentration of the dyeing aqueous solution is preferably 15.0 mM or less Do.

[Evaluation of Appearance]

In the dyeing step (4), the elution and decolorization by dissolution of the polyvinyl alcohol-based resin in the dyeing bath were visually confirmed. The case where the dissolution and the discoloration were not confirmed together and the appearance was good was referred to as " good ", and the case where either dissolution or discoloration was observed was referred to as " defect ". The results are shown in Table 1.

[Measurement of Piercing Strength]

The base film was peeled off from the polarizing laminated film obtained in the above (4), and the polarizing film was taken out to obtain a sample for evaluation. First, the thickness of the polarizing film of the evaluation sample was measured with a contact type film thickness meter (trade name "DIGIMICRO MH-15M", manufactured by Nikon Corporation). Thereafter, using a handy compression tester "KES-G5 Needle Penetration Measurement Specification " manufactured by KATO TECH CO., LTD. Equipped with needles having tip diameters of 1 mmφ and 0.5 R, a piercing speed of 0.33 cm < 2 > / sec, and the force applied to the needle when it passed through the polarizing film was measured. This measurement was carried out on the twelve evaluation samples, and the average value was used as a measurement value of the sample. The piercing strength per unit thickness was calculated by dividing the measured value by the thickness of the polarizing film. The results are shown in Table 1.

[Measurement of Ty and Py]

("P-3132" manufactured by LINTEC CO., LTD.) Was bonded to the polarizing film side of the polarizing plate with a single-sided protective film obtained in the above (5) while corona treatment was performed on the polarizing film side. A polarizing plate having the obtained pressure-sensitive adhesive layer was bonded to the glass using the pressure-sensitive adhesive layer to obtain a sample for evaluation. With respect to the polarizing plate of the evaluation sample, the transmittance and the degree of polarization were measured using a spectrophotometer ("V7100" manufactured by Nihon Bunko Co., Ltd.) equipped with an integrating sphere by using a two-view field (C light source) of JIS Z 8701 The visual sensitivity-corrected single-beam transmittance Ty and the visual sensitivity correction polarization degree Py were measured. In the measurement, a sample for evaluation was set so that incident light was irradiated on the glass side. The results are shown in Table 1.

Claims

As a stretched film made of a polyvinyl alcohol-based resin containing a lamellar crystal,
Wherein a thickness L (nm) of the lamellar crystal calculated by the following formula (1) is 13.0 nm or more and 45.0 nm or less, using a crystal melting peak temperature T (K) measured by differential scanning calorimetry measurement of the stretched film: A stretched film used for manufacturing a film.
L = 0.66 x {516 / (516-T)} (1)

The stretched film according to claim 1, wherein the polyvinyl alcohol-based resin comprises, as a constituent monomer, a monomer controlling the thickness L (nm) of the lamellar crystal.

The stretched film according to claim 1 or 2, which is obtained by stretching a polyvinyl alcohol-based resin layer formed on a base film.

A polarizing film obtained by dying the stretched film according to claim 1 or 2 with a dichroic dye.

A polarizing film obtained by dying the stretched film according to claim 3 with a dichroic dye.

The polarizing film according to claim 4, wherein the piercing strength per unit thickness is 6.0 g / 탆 or more.

The polarizing film according to claim 5, wherein the piercing strength per unit thickness is 6.0 g / 탆 or more.

5. A polarizing plate comprising: the polarizing film according to claim 4;
And a protective film laminated on at least one side of the polarizing film.

A polarizing plate comprising the polarizing film according to claim 5,
And a protective film laminated on at least one side of the polarizing film.

A polarizing plate comprising the polarizing film according to claim 6,
And a protective film laminated on at least one side of the polarizing film.

A polarizing plate comprising the polarizing film according to claim 7,
And a protective film laminated on at least one side of the polarizing film.