JP2015169677A - Manufacturing method of polarizing laminated film and manufacturing method of polarizing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a polarizing laminated film having a high coating property of a hydrophilic polymer layer to a base film so that a fold can be prevented from occurring during manufacture.SOLUTION: A manufacturing method of a polarizing laminated film formed by lamination of at least a base film and a polarizer comprises the steps of: laminating a hydrophilic polymer layer containing a hydrophilic polymer to form a laminated film, by sequential coating or co-extrusion onto the base film that contains two or more kinds of resin including at least carboxylic acid vinyl ester resin and has two or more of glass transition points T1, T2; extending the laminated film; and dyeing the hydrophilic polymer layer with a dichroic substance.

Description

  The present invention relates to a method for producing a polarizing laminate film and a method for producing a polarizing plate. In particular, the present invention relates to a method for producing a polarizing laminated film and a method for producing a polarizing plate, in which the hydrophilic polymer layer has high applicability to a base film and can suppress the occurrence of folding during transportation.

  A polarizing plate is widely used as a polarization supplying element in a display device such as a liquid crystal display device. As such a polarizing plate, a polarizing plate made of polyvinyl alcohol resin and a polarizing plate protective film made of triacetyl cellulose or the like are conventionally used. However, in recent years, notebook personal computers and mobile phones for liquid crystal display devices have been used. With the development of mobile devices, etc., there is a need to reduce the thickness and weight.

  After providing a hydrophilic polymer layer made of a polyvinyl alcohol-based resin on the surface of the base film as a method for obtaining such a thin polarizer, the laminated film is stretched and dyed to form a thin film on the base film. A method for manufacturing a polarizing laminated film in which polarizers are laminated has been proposed (see, for example, Patent Documents 1 to 3).

  According to the above conventional method, a layer is formed by coating an aqueous solution of a polyvinyl alcohol resin directly on the surface of the base film, and by stretching, compared with the case of using the original film of the polyvinyl alcohol resin. There is an advantage that a remarkably thin hydrophilic polymer layer (polarizer) can be formed.

However, in the above conventional manufacturing method, the base film is formed using a polyethylene terephthalate resin, a polypropylene resin, or the like, and the coating property between the base film and the hydrophilic polymer layer (polarizer). May be insufficient. For this, a method of providing an easy-adhesion layer between them may be considered, but the thickness of the entire polarizing laminate film increases, and a new process for forming the easy-adhesion layer increases. Is not preferable.
In the above conventional production method, the crosslinking treatment of the polyvinyl alcohol-based resin is performed in a crosslinking solution containing boric acid. However, in the drying step after the crosslinking treatment, the boric acid crosslinking proceeds remarkably and becomes hydrophilic in the width direction. A phenomenon may occur in which the polymer layer contracts and both ends of the base film warp toward the hydrophilic polymer layer. If the laminated film is continuously flown in this state, the end of the base film may be folded at the drying furnace or at the outlet of the drying furnace. Further, there is a problem that a load is generated on the laminated film due to stretching, and cracks are easily generated in the stretching direction in the subsequent steps (for example, see Patent Document 4).
Since the base film used in the conventional manufacturing method has a low Tg and a softness so that it can be stretched at a high magnification, the rigidity of the base film is lost due to the shrinkage force caused by the crosslinking of the polyvinyl alcohol-based resin. For this reason, it is considered that the above phenomenon occurs. As a countermeasure against the folding of the base film, after forming a hydrophilic polymer layer on one side of the base film, the support film is pasted on the other side, and then the laminated film is stretched. Has been proposed, but the steps of laminating and peeling the support film are increased, the process becomes complicated, and the cost increases.

JP 2012-68677 A JP 2013-011837 A JP 2013-011838 A JP 2012-133295 A

  The present invention has been made in view of the above-described problems and circumstances, and the problem to be solved is a polarizing laminate capable of suppressing the occurrence of folding during transportation with high applicability of the hydrophilic polymer layer to the base film. It is providing the manufacturing method of a film, and the manufacturing method of a polarizing plate.

  As a result of investigating the cause of the above-mentioned problems in order to solve the above-mentioned problems according to the present invention, it is a method for producing a polarizing laminated film in which at least a base film and a polarizer are laminated, and at least a carboxylic acid vinyl ester A hydrophilic polymer layer containing a hydrophilic polymer is laminated by sequential coating or coextrusion on the base film containing two or more resins including a resin and having at least two glass transition points. A step of forming a laminated film, a step of stretching the laminated film, and a step of dyeing the hydrophilic polymer layer with a dichroic substance. It has been found that a method for producing a polarizing laminate film and a method for producing a polarizing plate can be provided that have high adhesion and can suppress the occurrence of folding during conveyance.

1. A method for producing a polarizing laminated film comprising at least a base film and a polarizer laminated,
A hydrophilic high polymer containing a hydrophilic polymer by sequential coating or coextrusion on the base film containing at least two kinds of resins including at least a carboxylic acid vinyl ester resin and having at least two glass transition points. A step of laminating molecular layers to form a laminated film;
Stretching the laminated film;
Dyeing the hydrophilic polymer layer with a dichroic substance;
A method for producing a polarizing laminated film, comprising:

  2. In the step of stretching the laminated film, the stretching temperature of the laminated film is a temperature between at least two glass transition points of the substrate film. Production method.

  3. 3. The method for producing a polarizing laminated film according to item 1 or 2, wherein the highest glass transition point among at least two glass transition points of the substrate film is 70 ° C. or higher.

  4). The temperature difference between the highest glass transition point and the lowest glass transition point among at least two or more glass transition points of the base film is 30 ° C. or more. The manufacturing method of the light-polarizing laminated film as described in any one of these.

  5. The polarizing film according to any one of Items 1 to 4, wherein the base film contains at least one kind of resin having a weight average molecular weight of 100,000 to 1,000,000. Production method.

  6). The mass composition ratio of the carboxylic acid vinyl ester resin (resin A) contained in the base film is (rA), and the resin other than the carboxylic acid vinyl ester resin among the two or more kinds of resins contained in the base film And when the mass composition ratio of the resin having the highest glass transition point (resin B) is (rB), it is in the range of (rA) :( rB) = 9: 1 to 1: 9. The manufacturing method of the light-polarizing laminated film as described in any one of 1st term | claim to 5th term.

  7). The thickness of the said base film after the process of extending | stretching the said laminated | multilayer film, and the process of dye | staining the said hydrophilic polymer layer exists in the range of 10-60 micrometers, The 1st to 6th features characterized by the above-mentioned. The manufacturing method of the light-polarizing laminated film as described in any one of the above.

  8). In the step of forming the laminated film, the base is obtained by casting a dope containing at least two kinds of resins including a carboxylic acid vinyl ester resin and a solvent on a metal support, separating the dope, and drying the dope. A polarizing film according to any one of items 1 to 7, wherein a material film is formed, and the hydrophilic polymer is laminated on the formed substrate film by a solution casting method. A method for producing a laminated film.

9. In the step of stretching the laminated film, the laminated film is uniaxially stretched at a stretch ratio of 4 times or more,
The process of forming the laminated film, the process of stretching the laminated film, and the process of dyeing the hydrophilic polymer layer are performed in this order, according to any one of items 1 to 8 The manufacturing method of the polarizing laminated film of description.

10. In the step of stretching the laminated film, the laminated film is wet-stretched in an aqueous boric acid solution,
The step of forming the laminated film, the step of dyeing the hydrophilic polymer layer, and the step of stretching the base film are performed in this order, any one of items 1 to 8 The manufacturing method of the polarizing laminated film of description.

  11. The method for producing a polarizing laminated film according to item 10, wherein a step of stretching the laminated film in the air is performed before the step of dyeing the hydrophilic polymer layer.

  12 Following the step of producing a polarizing laminate film by the method for producing a polarizing laminate film according to any one of Items 1 to 11, at least one surface of the polarizer of the polarizing laminate film The manufacturing method of the polarizing plate characterized by having the process of sticking a polarizing plate protective film on the surface.

  13. In the step of bonding the polarizing plate protective film, after peeling the base film from the polarizing laminated film, the polarizing plate protective film is bonded to the surface of the polarizer that is in contact with the base film. 13. A method for producing a polarizing plate according to item 12, wherein

ADVANTAGE OF THE INVENTION According to this invention, the applicability | paintability of the hydrophilic polymer layer with respect to a base film is high, and the manufacturing method of the polarizing laminated film which can suppress generation | occurrence | production of the folding at the time of conveyance, and the manufacturing method of a polarizing plate can be provided. .
The expression mechanism or action mechanism of the effect of the present invention is not clear, but is presumed as follows.
Since the base film contains at least two kinds of resins including a carboxylic acid vinyl ester resin and has at least two glass transition points, the carboxylic acid vinyl ester resin and the other resin are not in a compatible state but in a microscopic state. It is thought that it will be in the state of phase separation. Therefore, the physical properties of the base film can exhibit the respective properties of the carboxylic acid vinyl ester resin and other resins, and good handling properties during the stretching process due to the carboxylic acid vinyl ester resin and other resins It is speculated that it is possible to achieve both effects due to the above. As a result, the rigidity of the base film can be increased, and even if the hydrophilic polymer layer shrinks due to cross-linking of polyvinyl alcohol resin or loss of moisture, the base film does not curl the polarizing laminated film. Occurrence can be suppressed. For this reason, the folding at the time of manufacture can be suppressed.
The base film contains a carboxylic acid vinyl ester resin, and the carboxylic acid vinyl ester resin such as polyvinyl acetate is a raw material for a hydrophilic polymer material such as polyvinyl alcohol contained in the hydrophilic polymer layer. Therefore, it is presumed that the affinity between the base film and the hydrophilic polymer layer is high and the coating property of the hydrophilic polymer layer can be improved. In the present invention, the coating property is an evaluation of how uniformly the hydrophilic polymer layer can be formed on the base film, and the hydrophilic polymer layer is applied on the base film. It is used not only when forming by carrying out, but also when co-extrusing a base film and a hydrophilic polymer layer.

A diagram schematically showing the results of differential thermal analysis using a differential scanning calorimeter

The method for producing a polarizing laminated film of the present invention is a method for producing a polarizing laminated film in which at least a base film and a polarizer are laminated, and at least two kinds of resins containing a carboxylic acid vinyl ester resin are used. A step of laminating a hydrophilic polymer layer containing a hydrophilic polymer by sequential coating or coextrusion on the base film having at least two glass transition points, and forming a laminated film; It has the process of extending | stretching the said laminated | multilayer film, and the process of dye | staining the said hydrophilic polymer layer with a dichroic substance, It is characterized by the above-mentioned. This feature is a technical feature common to or corresponding to each of claims 1 to 13.
In the step of stretching the laminated film according to the present invention, it is preferable that the stretching temperature of the laminated film is a temperature between at least two glass transition points of the base film. Thereby, the conveyance property after an extending process can be made favorable.
In the present invention, the highest glass transition point among at least two glass transition points of the substrate film is preferably 70 ° C. or higher. Thereby, the rigidity of a base film is improved and the inhibitory effect of the folding at the time of conveyance can further be improved.
In the present invention, it is preferable that a temperature difference between the highest glass transition point and the lowest glass transition point among at least two glass transition points of the base film is 30 ° C. or more. Thereby, affinity with a base film and a hydrophilic polymer layer can be improved, and orientation nonuniformity can be reduced.
In the present invention, it is preferable that the base film contains at least one resin having a weight average molecular weight of 100,000 to 1,000,000. Thereby, the rigidity of a base film is improved and the inhibitory effect of the folding at the time of conveyance can further be improved.
In the present invention, the mass composition ratio of the carboxylic acid vinyl ester resin (resin A) contained in the base film is (rA), and the carboxylic acid among the two or more kinds of resins contained in the base film. When the mass composition ratio of the resin (resin B) other than the vinyl ester resin and having the highest glass transition point is (rB), the range is (rA) :( rB) = 9: 1 to 1: 9. It is preferable from the viewpoint of obtaining the effect of the present invention.
Moreover, it is preferable that the thickness of the said base film after the process of extending | stretching the said laminated | multilayer film and the process of dyeing | staining the said hydrophilic polymer layer is in the range of 10-60 micrometers. Thereby, while being able to manufacture a thinner polarizing laminated film, productivity can be improved.
Further, in the step of forming the laminated film, the present invention casts a dope containing at least two kinds of resins containing a carboxylic acid vinyl ester resin and a solvent on a metal support, and after peeling, Preferably, the base film is formed by drying, and the hydrophilic polymer is laminated on the formed base film by a solution casting method. Thereby, the rigidity of a base film is improved by this and the suppression effect of the folding at the time of conveyance can further be improved.
Further, in the step of stretching the laminated film, the present invention includes a step of uniaxially stretching the laminated film at a stretching ratio of 4 times or more to form the laminated film, a step of stretching the laminated film, and the hydrophilic high The steps of dyeing the molecular layer are preferably performed in this order. Thereby, it is hard to apply stress between a base film and a hydrophilic polymer layer, and orientation unevenness can be reduced.
Further, the present invention provides the step of stretching the laminated film, wet-stretching the laminated film in a boric acid aqueous solution to form the laminated film, dyeing the hydrophilic polymer layer, and the laminated film. It is preferable to perform the process of extending | stretching in this order. Thereby, the applicability | paintability of the hydrophilic polymer layer with respect to a base film can be improved.
Moreover, it is preferable that this invention performs the process of extending | stretching the said laminated | multilayer film in air before the process of dye | staining the said hydrophilic polymer layer. Thereby, the applicability | paintability of the hydrophilic polymer layer with respect to a base film can further be improved.
Moreover, the manufacturing method of the polarizing plate of this invention is a polarizing plate on the at least one surface of the said polarizer of the said polarizing laminated film following the process of manufacturing a polarizing laminated film with the manufacturing method of the said polarizing laminated film. It has the process of bonding a protective film, It is characterized by the above-mentioned. Since the applicability of the hydrophilic polymer layer to the base film is good, a polarizing plate with little alignment unevenness can be produced.
Further, in the present invention, the step of laminating the polarizing plate protective film includes the step of peeling the base film from the polarizing laminated film, and then the polarizing plate on the surface of the polarizer that is in contact with the base film. It is preferable to bond a protective film.

  Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In addition, in this application, "-" is used in the meaning which includes the numerical value described before and behind that as a lower limit and an upper limit.

<Configuration of polarizing laminated film>
A polarizing laminated film produced by the method for producing a polarizing laminated film of the present invention comprises at least two kinds of resins including at least a carboxylic acid vinyl ester resin, and a base film having at least two glass transition points. And a polarizer obtained by stretching a hydrophilic polymer layer containing a hydrophilic polymer and dyeing it with a dichroic substance.
Thus, the polarizing laminated film according to the present invention is constituted by laminating at least the base film and the polarizer.

  Hereinafter, each component will be described in detail.

<Base film>
The base film according to the present invention contains at least two kinds of resins including at least a carboxylic acid vinyl ester resin and has at least two glass transition points.

  The base film according to the present invention contains two or more kinds of resins including a carboxylic acid vinyl ester resin, and among them, at least one kind of resin having a weight average molecular weight in the range of 100,000 to 1,000,000. It is preferable to include. Thereby, the rigidity of a base film is improved and the inhibitory effect of the folding at the time of conveyance can further be improved.

  Hereinafter, the material used for the base film according to the present invention will be described.

(1) Carboxylic acid vinyl ester resin The carboxylic acid vinyl ester resin according to the present invention is preferably produced using a carboxylic acid represented by the following general formula (A).

General formula (A) R ₁ COOH
(In the formula, R ₁ represents a substituted or unsubstituted monovalent hydrocarbon group.)

In the method for producing a carboxylic acid vinyl ester resin according to the present invention, the raw material is an aliphatic carboxylic acid or an aromatic carboxylic acid represented by the general formula (A), and R _{1 in} the formula is a monovalent hydrocarbon group or A substituted monovalent hydrocarbon group in which part or all of the hydrogen atoms bonded to the carbon atoms of these groups are substituted with a halogen atom, a cyano group, an amino group or the like. Examples thereof include alkyl groups such as methyl, ethyl, propyl, butyl, undecyl, heptadecyl, octadecyl; alkenyl groups such as vinyl groups; aryl groups such as phenyl groups; one of hydrogen atoms bonded to carbon atoms of these groups It is a monovalent hydrocarbon group partially or entirely substituted with a halogen atom, a cyano group, an amino group or the like.

  That is, examples of the aliphatic carboxylic acid or aromatic carboxylic acid represented by the general formula (A) include saturated carboxylic acids such as formic acid, acetic acid, propionic acid, butyric acid, lauric acid, stearic acid; acrylic acid, (meth) acrylic Examples thereof include unsaturated carboxylic acids such as acid and crotonic acid; and aromatic carboxylic acids such as benzoic acid and cinnamic acid. For example, monochloroacetic acid etc. are illustrated as carboxylic acid which has a halogen substituted monovalent hydrocarbon group. In this invention, the other raw material used for manufacture of carboxylic acid vinyl ester resin is vinyl acetate.

  In the present invention, it is preferable to use (a) a palladium compound, (b) a lithium salt of carboxylic acid, and (c) a lithium halide as the catalyst. Examples of the palladium compound used as the catalyst include palladium carboxylates such as palladium acetate and palladium propionate; inorganic salts of palladium such as palladium chloride and palladium bromide; complex compounds of palladium, etc. Possible palladium compounds are not limited to these. In addition to the palladium compound catalyst, a lithium salt of carboxylic acid or lithium halide is used as a co-catalyst. Examples of lithium salts of carboxylic acids include lithium salts of lower aliphatic carboxylic acids mainly composed of lithium acetate, lithium propionate, etc., and examples of lithium halides include lithium chloride and lithium bromide, with lithium bromide being particularly preferred. However, the cocatalyst is not limited to these examples.

  The method for producing the carboxylic acid vinyl ester resin utilizes an ester exchange reaction. In performing this reaction, the molar ratio of the carboxylic acid and the vinyl acetate represented by the general formula (A) is determined by the transesterification reaction. It may be arbitrarily determined according to the equilibrium relationship. Also, once the unreacted vinyl acetate and by-produced acetic acid have been removed, the amount of vinyl acetate added when vinyl acetate is added again to continue the reaction can be arbitrarily determined according to the equilibrium relationship of the transesterification reaction. It ’s fine. Also, depending on the purpose, after removing unreacted vinyl acetate and by-product acetic acid from the re-reaction solution, the reaction rate of carboxylic acid can be increased by adding unreacted vinyl acetate again and reacting again. Can also be increased. The method for removing unreacted vinyl acetate and by-product acetic acid from the reaction solution is generally a distillation method, but the method for producing the vinyl carboxylate of the present invention is not limited thereto.

  In the carboxylic acid vinyl ester resin according to the present invention, a part or all of the cocatalyst may be added in advance to a mixed liquid of carboxylic acid and vinyl acetate. Further, since the solubility naturally varies depending on the type of carboxylic acid to be used, a solvent is selectively used depending on the solubility. As the solvent, tetrahydrofuran, acetonitrile and the like are suitable.

  Carboxylic acid vinyl ester resin according to the present invention is easy to expand due to heat, peelability from metal support during film production, drying of organic solvent, heat resistance and mechanical strength. The average molecular weight (Mw) is preferably in the range of 60,000 to 1,000,000, more preferably in the range of 100,000 to 1,000,000, and particularly preferably in the range of 200,000 to 800,000.

  If it is 60,000 or more, the mechanical strength is excellent, and if it is 1,000,000 or less, the solution casting method has excellent solubility, and the melt casting method does not require extrusion at high temperature. There is no resin degradation.

(2) Other resins Among the resins contained in the base film according to the present invention, as the resin other than the carboxylic acid vinyl ester resin, those having a glass transition point higher than that of the carboxylic acid vinyl ester resin are preferable. An acrylic resin, urethane resin, acrylonitrile resin, cellulose ester resin, polyvinyl alcohol resin, or the like can be used.

(2-1) Acrylic resin The base film according to the present invention may contain an acrylic resin together with a carboxylic acid vinyl ester resin. The acrylic resin contained in the base film is a polymer of acrylic acid ester or methacrylic acid ester, and includes a copolymer with other monomers.

  Therefore, the acrylic resin according to the present invention includes a methacrylic resin. The resin is not particularly limited, but the methyl methacrylate unit is in the range of 50 to 99% by mass, and the other monomer units copolymerizable therewith are in the range of 1 to 50% by mass. Is preferred.

  Other units constituting the acrylic resin formed by copolymerization include alkyl methacrylates having 2 to 18 carbon atoms, alkyl acrylates having 1 to 18 carbon atoms, isobornyl methacrylate, 2-hydroxy Hydroxyalkyl acrylates such as ethyl acrylate, α, β-unsaturated acids such as acrylic acid and methacrylic acid, acrylamides such as acryloylmorpholine, Nhydroxyphenyl methacrylamide, N-vinylpyrrolidone, maleic acid, fumaric acid, itaconic acid, etc. Unsaturated group-containing divalent carboxylic acid, aromatic vinyl compounds such as styrene and α-methylstyrene, α, β-unsaturated nitriles such as acrylonitrile and methacrylonitrile, maleic anhydride, maleimide, N-substituted maleimide, glutarimide , Glutaric anhydride, etc. Can be mentioned.

  Examples of the copolymerizable monomer that forms a unit excluding glutarimide and glutaric anhydride from the above units include monomers corresponding to the above units. That is, alkyl methacrylate having 2 to 18 carbon atoms, alkyl acrylate having 1 to 18 carbon atoms, hydroxyalkyl acrylate such as isobornyl methacrylate and 2-hydroxyethyl acrylate, acrylic acid, methacrylic acid, etc. α, β-unsaturated acids, acrylamides such as acryloylmorpholine, N-hydroxyphenylmethacrylamide, unsaturated divalent carboxylic acids such as N-vinylpyrrolidone, maleic acid, fumaric acid, itaconic acid, styrene, α-methylstyrene And monomers such as α, β-unsaturated nitriles such as acrylonitrile and methacrylonitrile, maleic anhydride, maleimide, and N-substituted maleimide.

  Moreover, a glutarimide unit can be formed by, for example, reacting a primary amine (imidizing agent) with an intermediate polymer having a (meth) acrylic acid ester unit to imidize (see JP 2011-26563 A). ).

  The glutaric anhydride unit can be formed, for example, by heating an intermediate polymer having a (meth) acrylic acid ester unit (see Japanese Patent No. 496164).

  Among the above structural units, the acrylic resin according to the present invention includes, from the viewpoint of mechanical strength, isobornyl methacrylate, acryloylmorpholine, N-hydroxyphenylmethacrylamide, N-vinylpyrrolidone, styrene, hydroxyethyl methacrylate, and anhydrous maleic acid. It is particularly preferred that an acid, maleimide, N-substituted maleimide, glutaric anhydride or glutarimide is included.

  The acrylic resin according to the present invention is an improvement in the viewpoint of controlling the dimensional change with respect to the change in environmental temperature and humidity atmosphere, the peelability from the metal support during film production, the drying property of the organic solvent, the heat resistance and the mechanical strength. In view of the above, the weight average molecular weight (Mw) is preferably in the range of 50,000 to 1,000,000, more preferably in the range of 100,000 to 1,000,000, and in the range of 200,000 to 800,000. It is particularly preferred.

  If it is 50,000 or more, the heat resistance and mechanical strength are excellent, and if it is 1,000,000 or less, the peelability from the metal support and the drying property of the organic solvent are excellent.

  The weight average molecular weight (Mw) of the acrylic resin according to the present invention can be measured by gel permeation chromatography. The measurement conditions are as follows.

Solvent: Methylene chloride Column: Shodex K806, K805, K803G (Used by connecting three Showa Denko Co., Ltd.)
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (manufactured by GL Sciences)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corporation) A calibration curve with 13 samples in the range of Mw = 500 to 2800000 was used. The 13 samples are preferably used at approximately equal intervals.

  There is no restriction | limiting in particular as a manufacturing method of the acrylic resin which concerns on this invention, Any of well-known methods, such as suspension polymerization, emulsion polymerization, block polymerization, or solution polymerization, may be used. Here, as a polymerization initiator, a normal peroxide type and an azo type can be used, and a redox type can also be used. Regarding the polymerization temperature, suspension or emulsion polymerization may be carried out within a range of 30 to 100 ° C., and bulk or solution polymerization may be carried out within a range of 80 to 160 ° C. In order to control the reduced viscosity of the obtained copolymer, polymerization can be carried out using alkyl mercaptan or the like as a chain transfer agent.

  The glass transition temperature Tg of the acrylic resin is preferably in the range of 80 to 120 ° C. from the viewpoint of maintaining the mechanical strength of the film.

  A commercially available thing can also be used as an acrylic resin which concerns on this invention. For example, Delpet 60N, 80N, 980N, SR8200 (manufactured by Asahi Kasei Chemicals Corporation), Dianal BR52, BR80, BR83, BR85, BR88, EMB-143, EMB-159, EMB-160, EMB-161, Examples include EMB-218, EMB-229, EMB-270, EMB-273 (manufactured by Mitsubishi Rayon Co., Ltd.), KT75, TX400S, IPX012 (manufactured by Denki Kagaku Kogyo Co., Ltd.). Two or more acrylic resins can be used in combination.

  The acrylic resin according to the present invention preferably contains an additive. As an example of the additive, acrylic particles (rubber elastic particles) described in International Publication No. 2010/001668 are used to improve the mechanical strength of the film. And may be included for adjusting the rate of dimensional change. Examples of commercially available products of such a multilayer structure acrylic granular composite include, for example, “Metablene W-341” manufactured by Mitsubishi Rayon Co., “Kane Ace” manufactured by Kaneka Co., “Paraloid” manufactured by Kureha Co., Ltd., Rohm and Examples include “Acryloid” manufactured by Haas, “Staffroid” manufactured by Aika, Chemisnow MR-2G, MS-300X (manufactured by Soken Chemical Co., Ltd.), and “Parapet SA” manufactured by Kuraray. May be used alone or in combination of two or more.

  The volume average particle diameter of the acrylic particles is 0.35 μm or less, preferably 0.01 to 0.35 μm, more preferably 0.05 to 0.30 μm. If the particle size is a certain value or more, the film can be easily stretched under heating, and if the particle size is a certain value or less, the transparency of the resulting film is hardly impaired.

  The base film of the present invention preferably has a flexural modulus (JIS K7171) of 1500 MPa or less from the viewpoint of flexibility. The flexural modulus is more preferably 1300 MPa or less, and still more preferably 1200 MPa or less. This flexural modulus varies depending on the type and amount of acrylic resin and rubber elastic particles in the base film. For example, as the content of rubber elastic particles increases, the flexural modulus generally decreases. In addition, the flexural modulus is generally smaller when an acrylic resin is a copolymer of alkyl methacrylate and alkyl acrylate than a homopolymer of alkyl methacrylate.

(2-2) Urethane-based resin The base film according to the present invention can contain a urethane resin together with a carboxylic acid vinyl ester resin. In this case, the adhesiveness with respect to the hydrophilic polymer layer (polarizer) with respect to a base film improves.

  The urethane resin is not particularly limited, and is typically a resin obtained by reacting a polyol and a polyisocyanate. As the polyol, any polyol having two or more hydroxy groups in the molecule can be adopted. The polyol is, for example, a polyacryl polyol, a polyester polyol, or a polyether polyol. Two or more polyols may be combined.

  The polyacryl polyol is typically a copolymer of a (meth) acrylic acid ester monomer and a monomer having a hydroxyl group.

  The (meth) acrylic acid ester monomer is, for example, methyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, or cyclohexyl (meth) acrylate.

  Examples of the monomer having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, (Meth) acrylic acid hydroxyalkyl esters such as (meth) acrylic acid 4-hydroxybutyl and (meth) acrylic acid 2-hydroxypentyl; (meth) acrylic acid monoesters of polyhydric alcohols such as glycerin and trimethylolpropane; N -Methylol (meth) acrylamide.

  The polyacryl polyol may be a copolymer with another monomer. Other monomers are not limited as long as they can be copolymerized with the (meth) acrylic acid ester monomer and the monomer having a hydroxyl group.

  The other monomers include, for example, unsaturated monocarboxylic acids such as (meth) acrylic acid; unsaturated dicarboxylic acids such as maleic acid and anhydrides and mono- or diesters thereof; unsaturated nitriles such as (meth) acrylonitrile Unsaturated amides such as (meth) acrylamide and N-methylol (meth) acrylamide; Vinyl esters such as vinyl acetate and vinyl propionate; Vinyl ethers such as methyl vinyl ether; α-olefins such as ethylene and propylene; Halogenated α, β-unsaturated aliphatic monomers such as vinyl chloride and vinylidene chloride; α, β-unsaturated aromatic monomers such as styrene and α-methylstyrene.

  The polyester polyol is typically obtained by reacting a polybasic acid component with a polyol component. Examples of the polybasic acid component include orthophthalic acid, isophthalic acid, terephthalic acid, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, biphenyldicarboxylic acid, and tetrahydrophthalic acid. Aromatic dicarboxylic acids; oxalic acid, succinic acid, malonic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, dodecanedicarboxylic acid, octadecanedicarboxylic acid, tartaric acid, alkylsuccinic acid, Aliphatic dicarboxylic acids such as linolenic acid, maleic acid, fumaric acid, mesaconic acid, citraconic acid, itaconic acid; hexahydrophthalic acid, tetrahydrophthalic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, etc. Alicyclic dicarboxylic acids; Or, these acid anhydrides, alkyl esters, reactive derivative such as an acid halide.

  Examples of the polyol component include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, and 1,6-hexanediol. 1,8-octanediol, 1,10-decanediol, 1-methyl-1,3-butylene glycol, 2-methyl-1,3-butylene glycol, 1-methyl-1,4-pentylene glycol, 2 -Methyl-1,4-pentylene glycol, 1,2-dimethyl-neopentyl glycol, 2,3-dimethyl-neopentyl glycol, 1-methyl-1,5-pentylene glycol, 2-methyl-1,5 -Pentylene glycol, 3-methyl-1,5-pentylene glycol, 1,2-dimethylbutylene Coal, 1,3-dimethylbutylene glycol, 2,3-dimethylbutylene glycol, 1,4-dimethylbutylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, polypropylene glycol, 1,4-cyclohexanedimethanol, Examples include 1,4-cyclohexanediol, bisphenol A, bisphenol F, hydrogenated bisphenol A, hydrogenated bisphenol F, and the like.

  The polyether polyol is typically obtained by adding an alkylene oxide to a polyhydric alcohol by ring-opening polymerization. The polyhydric alcohol is, for example, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, glycerin, or trimethylolpropane. Examples of the alkylene oxide include ethylene oxide, propylene oxide, butylene oxide, styrene oxide, and tetrahydrofuran.

  Examples of the polyisocyanate include tetramethylene diisocyanate, dodecamethylene diisocyanate, 1,4-butane diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, Aliphatic diisocyanates such as 2-methylpentane-1,5-diisocyanate and 3-methylpentane-1,5-diisocyanate; isophorone diisocyanate, hydrogenated xylylene diisocyanate, 4,4'-cyclohexylmethane diisocyanate, 1,4-cyclohexane Alicyclic diisocyanates such as diisocyanate, methylcyclohexylene diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane Tolylene diisocyanate, 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 4,4'-dibenzyl diisocyanate, Aromatic diisocyanates such as 1,5-naphthylene diisocyanate, xylylene diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate; dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, α, α, α, α-tetramethyl An aromatic aliphatic diisocyanate such as xylylene diisocyanate.

  The urethane resin preferably has a carboxy group. By having a carboxy group, easy adhesion is improved. This effect is particularly remarkable in a high temperature and high humidity environment.

  A urethane resin having a carboxy group can be obtained, for example, by reacting a chain extender having a free carboxy group in addition to a polyol and a polyisocyanate. Examples of the chain extender having a free carboxy group include dihydroxycarboxylic acid and dihydroxysuccinic acid. The dihydroxycarboxylic acid is a dialkyrol alkanoic acid such as dimethylol alkanoic acid (for example, dimethylol acetic acid, dimethylol butanoic acid, dimethylol propionic acid, dimethylol butyric acid, dimethylol pentanoic acid).

  The acid value of the urethane resin is preferably 10 or more, more preferably 10 to 50, and particularly preferably 20 to 45. In these cases, the adhesion with the polarizer is further improved.

  The urethane resin may be obtained by reaction with other polyols or other chain extenders in addition to the components described above.

  Other polyols include, for example, sorbitol, 1,2,3,6-hexanetetraol, 1,4-sorbitan, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerin, trimethylolethane , Trimethylolpropane, pentaerythritol, and other polyols having three or more hydroxyl groups.

  Other chain extenders include, for example, ethylene glycol, diethylene glycol, triethylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, 1,6- Glycols such as hexanediol and propylene glycol; Aliphatic diamines such as ethylenediamine, propylenediamine, hexamethylenediamine, 1,4-butanediamine, and aminoethylethanolamine; Fats such as isophorone diamine and 4,4'-dicyclohexylmethanediamine Cyclic diamines; aromatic diamines such as xylylenediamine and tolylenediamine.

  The urethane resin can be formed by applying a known method. This method is, for example, a one-shot method in which each component is reacted at once, or a multi-stage method in which the components are reacted stepwise. The urethane resin having a carboxy group is preferably formed by a multistage method because the introduction of the carboxy group is easy. The catalyst used for forming the urethane resin is not particularly limited.

  When a urethane resin is contained in the base film, the base film-forming resin composition used for forming the base film preferably includes a neutralizing agent. In this case, the stability of the urethane resin in the base film-forming resin composition is improved. Examples of the neutralizing agent include ammonia, N-methylmorpholine, triethylamine, dimethylethanolamine, methyldiethanolamine, triethanolamine, morpholine, tripropylamine, ethanolamine, triisopropanolamine, 2-amino-2-methyl-1- Examples include propanol.

  When the resin composition for forming a base film containing a urethane resin is aqueous, it is preferable to use an organic solvent that is inactive with respect to the polyisocyanate and is compatible with water when the urethane resin is formed. Examples of the organic solvent include ester solvents such as ethyl acetate, butyl acetate, and ethyl cellosolve acetate; ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; ether solvents such as dioxane, tetrahydrofuran, and propylene glycol monomethyl ether. is there.

The resin composition for forming a base film containing a urethane resin preferably contains a crosslinking agent, and in this case, easy adhesion is improved. The crosslinking agent is not particularly limited. When the urethane resin has a carboxy group, the crosslinking agent is preferably a polymer having a group capable of reacting with the carboxy group.
Examples of the group capable of reacting with a carboxy group include an organic amino group, an oxazoline group, an epoxy group, and a carbodiimide group, and an oxazoline group is preferable. The crosslinking agent having an oxazoline group has a long pot life at room temperature when mixed with a urethane resin, and has a good workability because the crosslinking reaction proceeds by heating. The polymer is, for example, a (meth) acrylic polymer or a styrene / acrylic polymer, and a (meth) acrylic polymer is preferable. When the crosslinking agent is a (meth) acrylic polymer, the performance of the easy adhesion layer is further improved. In addition to this, the (meth) acrylic polymer is stably compatible with the water-based easy-adhesive composition and crosslinks the urethane resin well.

  In the resin composition for forming a base film containing a urethane resin, the content of the urethane resin in the composition is preferably 1.5 to 15% by mass, and more preferably 2 to 10% by mass. When this resin composition further contains a crosslinking agent, the content of the crosslinking agent is preferably 1 to 30 parts by mass and more preferably 3 to 20 parts by mass with respect to 100 parts by mass of the urethane resin (solid content). The content of fine particles in the base film-forming resin composition containing a urethane resin is preferably 0.3 to 10 parts by mass, and 0.5 to 1 part by mass with respect to 100 parts by mass of the urethane resin (solid content). More preferred.

(2-3) Acrylonitrile resin The base film according to the present invention may contain an acrylonitrile resin together with a carboxylic acid vinyl ester resin.

  The acrylonitrile resin may be not only an acrylonitrile homopolymer but also a copolymerized with one or more compounds that can be copolymerized with acrylonitrile. Such a compound is not particularly limited. For example, rubber components such as nitrile rubber (NBR), alkyl acrylates such as methyl acrylate and ethyl acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, Alkyl (meth) acrylates such as propyl (meth) acrylate, butyl (meth) acrylate, 2-ethyl (meth) acrylate, 2-ethylhexyl methacrylate, (meth) acrylic acids such as acrylic acid and methacrylic acid, vinyl chloride, Haloolefins such as vinyl fluoride and vinylidene chloride, vinylamides such as acrylamide and vinylpyrrolidone, vinyl aromatic compounds such as styrene, vinyl carboxylic acids, vinyl sulfonic acids, maleic anhydride, etc. Acids, N- Examples thereof include maleimides such as phenylmaleimide, N-methylmaleimide and N-cyclohexylmaleimide, vinyl esters such as vinyl acetate, and glycidyl group-containing monomers such as glycidyl methacrylate. The proportion of the compound to be copolymerized is preferably 30 mol% or less, and more preferably 15 mol% or less.

Vinyl aromatic compounds have the function of increasing the water resistance of acrylonitrile resins. The vinyl aromatic compounds are preferably styrene compounds. Specific examples of the styrenic compound include styrene; alkyl-substituted styrenes such as α-methylstyrene, β-methylstyrene, and p-methylstyrene; halogen-substituted styrenes such as 4-chlorostyrene and 4-bromostyrene; p- Hydroxystyrenes such as hydroxystyrene, α-methyl-p-hydroxystyrene, 2-methyl-4-hydroxystyrene, 3,4-dihydroxystyrene; vinylbenzyl alcohols; p-methoxystyrene, p-tert-butoxystyrene, alkoxy-substituted styrenes such as m-tert-butoxystyrene; vinyl benzoic acids such as 3-vinylbenzoic acid and 4-vinylbenzoic acid; 4-vinylbenzyl acetate; 4-acetoxystyrene; 2-butylamidostyrene, 4-methyl Amidostyrene, p-sulfonami Amidostyrenes such as styrene; Aminostyrenes such as 3-aminostyrene, 4-aminostyrene, 2-isopropenylaniline and vinylbenzyldimethylamine; Nitrostyrenes such as 3-nitrostyrene and 4-nitrostyrene; 3- Examples include cyanostyrenes such as cyanostyrene and 4-cyanostyrene; vinylphenylacetonitrile; arylstyrenes such as phenylstyrene, and indenes.
Among them, styrene and α-methylstyrene are preferable, and styrene is particularly preferable because it can be compatible with other styrene resins and (meth) acrylic resins. These aromatic vinyl monomers may be used alone or in combination of two or more.

  As a method for obtaining acrylonitrile resin, for example, a monomer, an initiator, a solvent, etc. are continuously fed into a complete stirring and mixing tank, continuously extracted from the reaction tank, and volatile components are removed by a devolatilization system when heated. A method is mentioned. It is preferable to minimize polymer retention in the devolatilization system.

  For example, in the production of styrene-acrylonitrile copolymer, emulsion polymerization method, suspension polymerization method and bulk polymerization method are generally used. As a method for narrowing the composition distribution, complete mixing type in bulk polymerization is used. Examples include the production method used by the reactor.

  Here, as a polymerization initiator, a normal peroxide type and an azo type can be used, and a redox type can also be used. Regarding the polymerization temperature, the suspension or emulsion polymerization can be carried out in a temperature range of 30 to 100 ° C., and the bulk or solution polymerization can be carried out in a temperature range of 80 to 160 ° C. In order to control the reduced viscosity of the obtained copolymer, polymerization can be carried out using alkyl mercaptan or the like as a chain transfer agent.

  For example, the polymerization is preferably carried out using a fully mixed reactor and in a full liquid state without the presence of a gas phase part, and the unreacted monomer after polymerization is preferably removed quickly. The removal of the unreacted monomer can be performed with a single-stage or multi-stage decompression device.

(2-4) Cellulose Ester Resin The base film according to the present invention can contain a cellulose ester resin together with a carboxylic acid vinyl ester resin.
The cellulose ester resin may be substituted with either an aliphatic acyl group or an aromatic acyl group, but is preferably substituted with an acetyl group.

  When the cellulose ester resin is an ester with an aliphatic acyl group, the aliphatic acyl group has 2 to 20 carbon atoms, specifically, acetyl, propionyl, butyryl, isobutyryl, valeryl, pivaloyl, hexanoyl, octanoyl , Lauroyl, stearoyl and the like.

When the cellulose ester resin is an ester with an aromatic acyl group, the number of substituents substituted on the aromatic ring is 0 or 1 to 5, preferably 1 to 3, particularly preferably 1 or Two.
Furthermore, when the number of substituents substituted on the aromatic ring is 2 or more, they may be the same or different from each other, but they are connected to each other to form a condensed polycyclic compound (for example, naphthalene, indene, indane, phenanthrene). Quinoline, isoquinoline, chromene, chroman, phthalazine, acridine, indole, indoline, etc.).

  The cellulose ester resin is a single or mixed acid ester of cellulose containing a structure of at least one of a substituted or unsubstituted aliphatic acyl group and a substituted or unsubstituted aromatic acyl group.

  As for the substitution degree of the cellulose ester resin, the total substitution degree (T) of the acyl group is 2.00 to 3.00, and the acetyl group substitution degree (ac) is 0 to 2.50. More preferably, the acyl group substitution degree (r) other than the acetyl group is 1.50 to 2.90.

  The acyl group other than the acetyl group preferably has 3 to 7 carbon atoms.

  As the cellulose ester resin, those having an acyl group having 2 to 7 carbon atoms as a substituent, that is, cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate benzoate And at least one selected from cellulose benzoate.

  Among these, particularly preferable cellulose ester resins include cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate, and cellulose acetate butyrate.

  More preferably, the mixed fatty acid is a lower fatty acid ester of cellulose acetate propionate or cellulose acetate butyrate and having an acyl group having 2 to 4 carbon atoms as a substituent.

  The portion that is not substituted with an acyl group usually exists as a hydroxyl group. These can be synthesized by known methods.

  In addition, the substitution degree of an acetyl group and the substitution degree of other acyl groups are obtained by a method prescribed in ASTM-D817-96.

  The weight average molecular weight (Mw) of the cellulose ester resin is preferably 75000 or more, more preferably about 1000000, but in view of productivity, 75000 to 280000 are preferable, and 100000 to 24000 are more preferable.

(2-5) Polyvinyl alcohol resin As a polyvinyl alcohol resin used for the base film which concerns on this invention, the thing similar to the polyvinyl alcohol resin used for the polarizer mentioned later can be used.

(3) Mixing ratio of carboxylic acid vinyl ester resin (resin A) and other resin (resin B) The base film according to the present invention has a mass composition ratio of carboxylic acid vinyl ester resin (resin A) to (rA), When the mass composition ratio of the resin (resin B) which is a resin other than the carboxylic acid vinyl ester resin and has the highest glass transition point among the two or more kinds of resins contained in the base film is (rB), It is preferable that rA) :( rB) = 9: 1 to 1: 9 from the viewpoint of achieving both mechanical strength and handleability during stretching.

  Preferably, it is within the range of (rA) :( rB) = 8: 2 to 2: 8, more preferably within the range of (rA) :( rB) = 7: 3 to 3: 7, particularly preferably , (RA) :( rB) = 6: 4 to 4: 6.

(4) Additive (4-1) Plasticizer The base film according to the present invention may contain a plasticizer. By containing the plasticizer, the mechanical strength, optical properties, moisture resistance, and the like of the base film can be improved.

  Examples of the plasticizer preferably used in the present invention include polyhydric alcohol esters, polycarboxylic acid esters (including phthalic acid esters), glycolate compounds, fatty acid esters, and phosphoric acid esters. These may be used alone or in combination of two or more.

(4-2) Antioxidant The base film according to the present invention may contain an antioxidant. The antioxidant is also referred to as a deterioration preventing agent, and can suppress the deterioration of the base film in a high humidity and high temperature environment. The antioxidant has a role of delaying or preventing the base film from being decomposed by, for example, a residual solvent amount of halogen in the base film or phosphoric acid of a phosphoric acid plasticizer.

  As such an antioxidant, a hindered phenol compound is preferably used. For example, 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di- -T-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3 -(3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino)- 1,3,5-triazine, 2,2-thio-diethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octa Sil-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, N, N'-hexamethylenebis (3,5-di-t-butyl-4-hydroxy-hydrocinnamamide) 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tris- (3,5-di-t-butyl-4-hydroxy Benzyl) -isocyanurate and the like.

  In particular, 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3 -(3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] is preferred. Further, for example, hydrazine-based metal deactivators such as N, N′-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine and tris (2,4-di- A phosphorus processing stabilizer such as t-butylphenyl) phosphite may be used in combination.

  The amount of these compounds added is preferably in the range of 1 ppm to 1.0%, more preferably in the range of 10 to 1000 ppm by mass ratio with respect to the resin in the base film.

(4-3) Ultraviolet Absorber The base film according to the present invention may contain an ultraviolet absorber. Thereby, the ultraviolet absorption function can be imparted to the base film.

  Although it does not specifically limit as a ultraviolet absorber, For example, ultraviolet absorbers, such as a benzotriazole type, 2-hydroxybenzophenone type, or a salicylic acid phenyl ester type, are mentioned. For example, 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2- (3 Triazoles such as 5-di-t-butyl-2-hydroxyphenyl) benzotriazole, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone And benzophenones.

  Of the UV absorbers, UV absorbers having a molecular weight of 400 or more are not sublimated or are not easily volatilized at a high boiling point. It is preferable from the viewpoint that the ultraviolet absorptivity can be expressed.

  Examples of the ultraviolet absorber having a molecular weight of 400 or more include 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2-benzotriazole, 2,2-methylenebis [4- ( 1,1,3,3-tetrabutyl) -6- (2H-benzotriazol-2-yl) phenol] and the like, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, Hindered amines such as bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and further 2- (3,5-di-t-butyl-4-hydroxybenzyl) -2-n-butyl Bis (1,2,2,6,6-pentamethyl-4-piperidyl) malonate, 1- [2- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy ] Hindered phenol and hindered amine in the molecule such as ethyl] -4- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy] -2,2,6,6-tetramethylpiperidine The hybrid type | system | group which has these structures is mentioned, These can be used individually or in combination of 2 or more types. Among these, 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2-benzotriazole and 2,2-methylenebis [4- (1,1,3,3- Tetrabutyl) -6- (2H-benzotriazol-2-yl) phenol] is particularly preferred.

  As these ultraviolet absorbers, commercially available products may be used. For example, Tinuvin 109, Tinuvin 171, Tinuvin 234, Tinuvin 326, Tinuvin 327, Tinuvin 328, Tinuvin 928, etc. manufactured by BASF Japan, or 2, 2'-methylenebis [6- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol] (molecular weight 659; examples of commercially available products are manufactured by ADEKA Corporation LA31) can be preferably used.

  The said ultraviolet absorber can be used individually by 1 type or in combination of 2 or more types.

  The amount of the UV absorber used is not uniform depending on the type of UV absorber, usage conditions, etc., but generally 0.05 to 10% by mass, preferably 0.1%, based on the resin in the base film. It is added in the range of ˜5% by mass.

  The UV absorber can be added by dissolving the UV absorber in an alcohol such as methanol, ethanol or butanol, an organic solvent such as methylene chloride, methyl acetate, acetone or dioxolane, or a mixed solvent thereof, or directly. It may be added.

  For an inorganic powder that does not dissolve in an organic solvent, a dissolver or a sand mill is used in the organic solvent and the resin, and then dispersed before addition.

(4-4) Fine particles (matting agent)
The base film according to the present invention may contain fine particles (mat agent). Thereby, the slipperiness of the surface of a base film can be improved.

  The fine particles may be inorganic fine particles or organic fine particles. Examples of inorganic fine particles include silicon dioxide (silica), titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, Examples include magnesium silicate and calcium phosphate. Among these, silicon dioxide and zirconium oxide are preferable, and silicon dioxide is more preferable in order to reduce the increase in haze of the obtained film.

  Examples of silicon dioxide fine particles include Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600, NAX50 (manufactured by Nippon Aerosil Co., Ltd.), Seahoster KE-P10, KE-P30, KE-P50, KE-P100 (manufactured by Nippon Shokubai Co., Ltd.) and the like are included. Among them, Aerosil R972V, NAX50, Seahoster KE-P30 and the like are particularly preferable because the coefficient of friction is reduced while keeping the turbidity of the obtained film low.

  The primary particle diameter of the fine particles is preferably in the range of 5 to 50 nm, and more preferably in the range of 7 to 20 nm. A larger primary particle size has a greater effect of increasing the slipperiness of the resulting film, but transparency tends to decrease. Therefore, the fine particles may be contained as secondary aggregates having a particle diameter in the range of 0.05 to 0.3 μm. The size of the primary particles or the secondary aggregates of the fine particles was observed with a transmission electron microscope at a magnification of 500,000 to 2,000,000 times, and the primary particles or secondary aggregates were observed. It can be determined as an average value of the particle diameter.

  The content of the fine particles is preferably in the range of 0.05 to 1.0% by mass and more preferably in the range of 0.1 to 0.8% by mass with respect to the resin in the base film.

(5) Formation method of base film As a formation method of the base film according to the present invention, a normal inflation method, a T-die method, a calendar method, a cutting method, a casting method, an emulsion method, a hot press method, etc. The forming method can be used, but from the viewpoint of suppressing coloring, suppressing foreign matter defects, optical defects such as die lines, etc., the forming method can be selected from a solution casting film forming method and a melt casting film forming method. The film-forming method is preferable from the viewpoint of controlling the distribution state of the carboxylic acid vinyl ester resin and other resins to obtain a uniform and smooth surface.

(5-1) Solution Casting Method Hereinafter, a film forming method for forming a base film according to the present invention by a solution casting method will be described.

  The base film according to the present invention is formed by dissolving a carboxylic acid vinyl ester resin, other resins, plasticizers, additives, and the like in a solvent to prepare a dope and filtering the prepared dope. The process of casting on a metal support to form a web, the process of peeling the formed web from the metal support to form a film, the process of stretching and drying the film, and the roll after cooling the dried film It is performed by a winding process. The base film according to the present invention preferably contains a carboxylic acid vinyl ester resin and other resins in a solid content in the range of 60 to 95% by mass.

  Hereinafter, each process will be described.

(5-1-1) Dissolution Treatment In an organic solvent mainly composed of a good solvent for the resin, the resin, and in some cases, the plasticizer or other compound according to the present invention is dissolved while stirring to form a dope. Or a process of mixing the plasticizer or other compound solution with the resin solution to form a dope that is a main solution.

  When the base film according to the present invention is produced by a solution casting method, an organic solvent useful for forming a dope can be used without limitation as long as it dissolves a resin, a plasticizer, and other compounds at the same time. it can.

  For example, as the chlorinated organic solvent, methylene chloride, as the non-chlorinated organic solvent, methyl acetate, ethyl acetate, amyl acetate, acetone, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, cyclohexanone, ethyl formate, 2,2,2-trifluoroethanol, 2,2,3,3-hexafluoro-1-propanol, 1,3-difluoro-2-propanol, 1,1,1,3,3,3-hexafluoro- Examples include 2-methyl-2-propanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 2,2,3,3,3-pentafluoro-1-propanol, and nitroethane. For example, methylene chloride, methyl acetate, ethyl acetate, acetone can be preferably used as the main solvent, methylene chloride or Particularly preferably ethyl.

  In addition to the organic solvent, the dope preferably contains a linear or branched aliphatic alcohol having 1 to 4 carbon atoms in the range of 1 to 40% by mass. When the proportion of alcohol in the dope increases, the web gels, and peeling from the metal support becomes easy.When the proportion of alcohol is small, the resin and other compounds can be dissolved in a non-chlorine organic solvent system. There is also a role to promote. In the formation of the base film, a method of forming a film using a dope having an alcohol concentration in the range of 0.5 to 15.0% by mass is applied in order to improve the flatness of the obtained base film. Can do.

  In particular, a dope composition in which a resin and other compounds are dissolved in a total amount of 15 to 45% by mass in a solvent containing methylene chloride and a linear or branched aliphatic alcohol having 1 to 4 carbon atoms. It is preferable that

  Examples of the linear or branched aliphatic alcohol having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, and tert-butanol. Methanol and ethanol are preferred because of the stability and boiling point of these inner dopes and relatively good drying properties.

  For dissolving a resin, plasticizer or other compound, a method carried out at normal pressure, a method carried out below the boiling point of the main solvent, a method carried out under pressure above the boiling point of the main solvent, JP-A-9-95544, It is possible to use various dissolution methods such as a method using a cooling dissolution method as described in JP-A-9-95557 or JP-A-9-95538, a method using a high pressure described in JP-A-11-21379. In particular, a method in which the pressure is applied above the boiling point of the main solvent is preferable.

  The concentration of the resin in the dope is preferably in the range of 10 to 40% by mass. After the compound is added to the dope during or after dissolution and dissolved and dispersed, it is filtered through a filter medium, defoamed, and sent to the next step with a liquid feed pump.

  Regarding dope filtration, it is preferable to filter the dope with a filter medium having a 90% collection particle diameter, for example, 10 to 100 times the average particle diameter of fine particles, preferably with a main filter equipped with a leaf disk filter.

  In the present invention, the filter medium used for filtration preferably has a low absolute filtration accuracy. However, if the absolute filtration accuracy is too small, the filter medium is likely to be clogged, and the filter medium must be frequently replaced. There is a problem of lowering productivity.

  Therefore, in the present invention, the filter medium used for the dope preferably has an absolute filtration accuracy of 0.008 mm or less, more preferably in the range of 0.001 to 0.008 mm, and more preferably in the range of 0.003 to 0.006 mm. A filter medium is more preferable.

  There are no particular restrictions on the material of the filter medium, and normal filter media can be used. However, plastic fiber filter media such as polypropylene and Teflon (registered trademark), and metal filter media such as stainless steel fibers are used to remove fibers. This is preferable.

In the present invention, the dope flow rate during filtration is preferably 10 to 80 kg / (h · m ² ), more preferably 20 to 60 kg / (h · m ² ). Here, if the flow rate of the dope at the time of filtration is 10 kg / (h · m ² ) or more, it becomes efficient productivity, and the flow rate of the dope at the time of filtration is within 80 kg / (h · m ² ). If so, the pressure applied to the filter medium is appropriate, and the filter medium is not damaged, which is preferable.

  The filtration pressure is preferably 3500 kPa or less, more preferably 3000 kPa or less, and even more preferably 2500 kPa or less. The filtration pressure can be controlled by appropriately selecting the filtration flow rate and the filtration area.

  In many cases, the main dope may contain about 10 to 50% by mass of the recycled material.

  The return material is, for example, a finely pulverized acrylic film, which is generated when the acrylic film is formed, and is obtained by cutting off both side parts of the film, or an acrylic film original that exceeds the specified value of the film due to scratches, etc. Anti is used.

  Moreover, as a raw material of resin used for dope preparation, what pelletized resin and another compound previously can be used preferably.

(5-1-2) Casting An endless metal support, such as a stainless steel belt, which rotates the dope, sends it to a pressure die through a liquid feed pump (for example, a pressurized metering gear pump), and rotates. A dope is cast from a pressure die slit to a casting position on a metal support such as a metal drum.

  The metal support in casting (casting) preferably has a mirror-finished surface. As the metal support, a stainless steel belt or a drum whose surface is plated with a casting is preferably used. The width of the cast can be in the range of 1 to 4 m, preferably in the range of 1.5 to 3 m, more preferably in the range of 2 to 2.8 m. The surface temperature of the metal support for casting treatment is set in the range of −50 ° C. to a temperature at which the solvent boils and does not foam, more preferably in the range of −30 to 0 ° C. A higher temperature is preferable because the web can be dried faster, but if it is too high, the web may foam or the flatness may deteriorate. A preferable support temperature is appropriately determined at 0 to 100 ° C, and more preferably 5 to 30 ° C. Alternatively, it is also a preferable method that the web is gelled by cooling and peeled from the drum in a state containing a large amount of residual solvent. The method for controlling the temperature of the metal support is not particularly limited, and there are a method of blowing warm air or cold air, and a method of contacting hot water with the back side of the metal support. It is preferable to use warm water because heat transfer is performed efficiently, so that the time until the temperature of the metal support becomes constant is short. When using warm air, considering the temperature drop of the web due to the latent heat of vaporization of the solvent, while using warm air above the boiling point of the solvent, there may be cases where wind at a temperature higher than the target temperature is used while preventing foaming. . In particular, it is preferable to perform drying efficiently by changing the temperature of the support and the temperature of the drying air during the period from casting to peeling.

  A pressure die that can adjust the slit shape of the die base portion and can easily make the film thickness uniform is preferable. Examples of the pressure die include a coat hanger die and a T die, and any of them is preferably used. The surface of the metal support is a mirror surface. In order to increase the film forming speed, two or more pressure dies may be provided on the metal support, and the dope amount may be divided and laminated.

(5-1-3) Solvent evaporation The web (the dope is cast on the casting support and the formed dope film is referred to as a web) is heated on the casting support to evaporate the solvent.

  To evaporate the solvent, there are a method of blowing air from the web side, a method of transferring heat from the back side of the support, a method of transferring heat from the front and back by radiant heat, etc. Is preferable. A method of combining them is also preferably used. The web on the support after casting is preferably dried on the support in an atmosphere of 40 to 100 ° C. In order to maintain the atmosphere at 40 to 100 ° C., it is preferable to apply hot air at this temperature to the upper surface of the web or to heat by means such as infrared rays.

  From the viewpoint of surface quality, moisture permeability, and peelability, it is preferable to peel the web from the support within 30 to 120 seconds.

(5-1-4) Peeling This is a process of peeling the web where the solvent has evaporated on the metal support at the peeling position. The peeled web is sent to the next process as a film.

  The temperature at the peeling position on the metal support is preferably in the range of 10 to 40 ° C, more preferably in the range of 11 to 30 ° C.

  In addition, it is preferable that the residual solvent amount at the time of peeling of the web on the metal support at the time of peeling is peeled in the range of 50 to 120% by mass depending on the strength of drying conditions, the length of the metal support, and the like. When peeling at a higher residual solvent amount, if the web is too soft, the flatness at the time of peeling is impaired, and slippage and vertical stripes are likely to occur due to the peeling tension. The amount of solvent is determined.

  The residual solvent amount of the web is defined by the following formula (Z).

Formula (Z)
Residual solvent amount (%) = (mass before web heat treatment−mass after web heat treatment) / (mass after web heat treatment) × 100
Note that the heat treatment for measuring the residual solvent amount represents performing heat treatment at 115 ° C. for 1 hour.

  The peeling tension when peeling the metal support from the film is usually in the range of 196 to 245 N / m. However, if wrinkles easily occur at the time of peeling, peeling may be done with a tension of 190 N / m or less. preferable.

  In the present invention, the temperature at the peeling position on the metal support is preferably in the range of −50 to 40 ° C., more preferably in the range of 10 to 40 ° C., and in the range of 15 to 30 ° C. Is most preferred.

(5-1-5) Drying The drying process can be divided into a preliminary drying process and a main drying process.
The web obtained by peeling from the metal support is dried. The web may be dried while being conveyed by a large number of rollers arranged above and below, or may be dried while being conveyed while being fixed with clips at both ends of the web like a tenter dryer. .

  The means for drying the web is not particularly limited and can be generally performed with hot air, infrared rays, a heating roller, microwaves, or the like, but it is preferably performed with hot air in terms of simplicity.

  The drying temperature in the drying process of the web is preferably a glass transition point of the film of −5 ° C. or lower, and it is effective to perform a heat treatment within a range of 10 to 60 minutes at a temperature of 100 ° C. or higher. Drying is performed at a drying temperature in the range of 100 to 200 ° C, more preferably in the range of 110 to 160 ° C.

(5-2) Melt Casting Method Hereinafter, a film forming method for forming the base film according to the present invention by the melt casting method will be described.

(Molded pellet manufacturing process)
In the case of performing the melt casting method, it is preferable that a mixture of a polymer for forming a base film and an additive is kneaded in advance and pelletized.

  Pelletization may be performed by a known method, for example, a polymer, a plasticizer, and other additives for forming a base film are fed to an extruder with a feeder and kneaded using a single or twin screw extruder, It can be obtained by extruding from a die in a strand shape, water cooling or air cooling and cutting.

  It is important to dry the raw material before extruding to prevent decomposition of the raw material. In particular, since the cellulose ester easily absorbs moisture, it is preferable to dry it at 70 to 140 ° C. for 3 hours or more with a dehumidifying hot air dryer or a vacuum dryer, and to keep the moisture content at 200 ppm or less, and further 100 ppm or less.

  Additives may be fed into the extruder and fed into the extruder, or may be fed through individual feeders. A small amount of an additive such as an antioxidant is preferably mixed in advance in order to mix uniformly.

  Mixing of the antioxidant may be mixed with each other, and if necessary, the antioxidant may be dissolved in a solvent and impregnated with a polymer for forming a base film, and mixed. Or you may spray and mix.

A vacuum nauter mixer or the like is preferable because drying and mixing can be performed simultaneously. Moreover, when contacting with air, such as an exit from a feeder part or a die, it is preferable that the atmosphere be dehumidified air or dehumidified N ₂ gas.

  The extruder is preferably processed at as low a temperature as possible so that the shearing force is suppressed and the resin can be pelletized so as not to deteriorate (molecular weight reduction, coloring, gel formation, etc.). For example, in the case of a twin screw extruder, it is preferable to rotate in the same direction using a deep groove type screw. From the uniformity of kneading, the meshing type is preferable.

  A film is formed using the pellets obtained as described above. It is also possible to feed the raw material powder directly to the extruder with a feeder and form a film as it is without pelletization.

(Process to extrude the molten mixture from the die to the cooling roll)
A line for introducing the polymer for forming the base film from the molten mixture to the casting die is provided, and the molten mixture is laminated in the casting die.

  First, using a single-screw or twin-screw type extruder, the melt temperature Tm at the time of extrusion is about 200 to 300 ° C., filtered through a leaf disk type filter or the like to remove foreign matters, and then from the T-die Extruded into a film, solidified on a cooling roll, and cast while pressing with an elastic touch roll.

  When introducing into the extruder from the supply hopper, it is preferable to prevent oxidative decomposition and the like under vacuum, reduced pressure, or inert gas atmosphere. Tm is the temperature of the die exit portion of the extruder.

  When foreign matter such as scratches or plasticizer aggregates adheres to the die, streak-like defects may occur. Such defects are also referred to as die lines, but in order to reduce surface defects such as die lines, it is preferable to have a structure in which the resin retention portion is minimized in the piping from the extruder to the die. . It is preferable to use a die that has as few scratches as possible inside the lip.

  The inner surface that comes into contact with the molten resin, such as an extruder or die, may be subjected to surface treatment that makes it difficult for the molten resin to adhere, such as by reducing the surface roughness or using a material with low surface energy. preferable. Specifically, a hard chrome plated or ceramic sprayed material is polished so that the surface roughness is 0.2 S or less.

  The cooling roll of the present invention is not particularly limited, but is a roll having a structure in which a heat medium or a coolant that can be controlled in temperature is flowed by a highly rigid metal roll, and the size is not limited. The diameter of the cooling roll is usually about 100 mm to 1 m as long as it is sufficient to cool the film.

  Examples of the surface material of the cooling roll include carbon steel, stainless steel, aluminum, and titanium. Further, in order to increase the hardness of the surface or improve the releasability from the resin, it is preferable to perform a surface treatment such as hard chrome plating, nickel plating, amorphous chrome plating, or ceramic spraying.

  The surface roughness of the surface of the cooling roll is preferably 0.1 μm or less in terms of Ra, and more preferably 0.05 μm or less. The smoother the roll surface, the smoother the surface of the resulting film. Of course, it is preferable to further polish the surface that has been subjected to surface processing so as to have the above-described surface roughness.

  As the elastic touch roll of the present invention, JP-A-03-124425, JP-A-08-224772, JP-A-07-1000096, JP-A-10-272676, International Publication No. 97/028950, It is possible to use a thin-film metal sleeve-covered silicon rubber roll whose surface is described in Kaihei 11-235747, JP-A 2002-36332, JP-A 2005-172940, JP-A 2005-280217. it can.

  When peeling the film from the cooling roll, it is preferable to control the tension to prevent deformation of the film.

(5-3) Stretching The base film formed by the solution casting method or the melt casting method can control the orientation of molecules in the film by being stretched, and the target retardation value Ro. And Rt can be obtained.

  The base film according to the present invention is preferably stretched in the longitudinal direction (also referred to as MD direction) and / or in the lateral direction (also referred to as TD direction), and the stretching ratio is at least 1 in the longitudinal direction or lateral direction. It is preferable to stretch within a range of 0.01 to 10 times.

  The stretching operation may be performed in multiple stages. Moreover, when performing biaxial stretching, simultaneous biaxial stretching may be performed and you may implement in steps. In this case, stepwise means that, for example, stretching in different stretching directions can be sequentially performed, stretching in the same direction is divided into multiple stages, and stretching in different directions is added to any one of the stages. Is also possible.

Thus, for example, the following stretching steps are possible:
-Stretch in the casting direction-> Stretch in the width direction-> Stretch in the casting direction-> Stretch in the casting direction-Stretch in the width direction-> Stretch in the width direction-> Stretch in the casting direction-> Stretch in the casting direction Simultaneous biaxial stretching includes stretching in one direction and contracting the other while relaxing the tension.

  The amount of residual solvent at the start of stretching is preferably in the range of 2 to 10% by mass.

  If the amount of the residual solvent is 2% by mass or more, the film thickness deviation is small and is preferable from the viewpoint of flatness, and if it is within 10% by mass, the surface unevenness is reduced, and the flatness is improved.

  The base film according to the present invention may be stretched in the MD direction and / or TD direction, preferably in the TD direction so that the film thickness after stretching is in a desired range. It is preferable to stretch in the temperature range of (TgL + 15) to (TgH + 50) ° C., where TgL is the lowest Tg and TgH is the highest Tg of the glass transition point (Tg) of the base film. If the stretching is performed within the above temperature range, the retardation can be easily adjusted, and the stretching stress can be reduced, so that the haze is lowered. Moreover, generation | occurrence | production of a fracture | rupture is suppressed and the base film excellent in planarity and the coloring property of the film itself is obtained. The stretching temperature is preferably in the range of (TgL + 20) to (TgH + 40) ° C.

  The base film according to the present invention preferably stretches the web at least in the MD direction or TD direction within a range of 1.01 to 10 times. The range of stretching is preferably 1.1 to 10 times the original width, and more preferably 1.2 to 8 times. If it is in the said range, the movement of the molecule | numerator in a film will be large and not only a desired phase difference value will be acquired, but a film can be thinned and the planarity of a film can be improved.

  In order to stretch in the MD direction, it is preferable to peel at a peeling tension of 130 N / m or more, and particularly preferably 150 to 170 N / m. Since the web after peeling is in a high residual solvent state, stretching in the MD direction can be performed by maintaining the same tension as the peeling tension. As the web dries and the residual solvent amount decreases, the stretch ratio in the MD direction decreases.

  In addition, the extending | stretching of MD direction can use the roller extending | stretching machine using the peripheral speed difference of a roller, and a draw ratio can be calculated from the rotational speed of a belt support body, and the operating speed of a roller extending | stretching machine.

  In order to stretch in the TD direction, for example, the entire drying process or a part of the process as shown in Japanese Patent Application Laid-Open No. 62-46625 can be performed while holding the width ends of the web with clips or pins in the width direction. A drying method (referred to as a tenter method), among them, a tenter method using clips and a pin tenter method using pins are preferably used.

  In stretching in the TD direction, stretching in the width direction of the film at a stretching speed of 250 to 500% / min is preferable from the viewpoint of improving the flatness of the film.

  If the stretching speed is 250% / min or more, the planarity is improved and the film can be processed at a high speed, which is preferable from the viewpoint of production aptitude, and if it is within 500% / min, the film is broken. Can be processed without any problem.

  A preferable stretching speed is in the range of 300 to 400% / min. The stretching speed is defined by the following formula (2).

Formula (2) Stretching speed (% / min) = [(d ₁ / d ₂ ) −1] × 100 (%) / t
(In the formula (2), d ₁ is the width dimension in the stretching direction of the resin film after stretching, d ₂ is the width dimension in the stretching direction of the resin film before stretching, and t is the time required for stretching ( min).)
The in-plane retardation value Ro and the thickness direction retardation value Rt of the base film according to the present invention are measured using an automatic birefringence meter Axoscan (Axo Scan Mueller Matrix Polarimeter: manufactured by Axometrics) at 23 ° C. environment of · 55% RH, at a wavelength of 590 nm, subjected to three-dimensional refractive index measured, resulting refractive indices _{n x,} n y, can be calculated from _{n z.}

  The substrate film according to the present invention has a retardation value (Ro) defined by the following formula (i) in the range of 0 to 70 nm, and a retardation value (Rt) defined by the following formula (ii). A range of −40 to 40 nm is preferable from the viewpoint of improving visibility such as viewing angle and contrast when the IPS liquid crystal display device is provided. The base film can be adjusted within the range of the retardation value by stretching while adjusting the stretching ratio at least in the MD direction or the TD direction. More preferable retardation values are within the range of Ro of 0 to 30 nm, Rt of -30 to 30 nm, particularly preferably Ro of 0 to 10 nm, and Rt of -20 to 20 nm. is there.

Formula _{(i): Ro = (n} x -n y) × d (nm)
Formula (ii): Rt = {(n _x + n _y ) / 2−n _z } × d (nm)
In [Equation (i) and Formula (ii), n _x represents a refractive index in the direction x in which the refractive index is maximized in the plane direction of the film. n _y, in-plane direction of the film, the refractive index in the direction y perpendicular to the direction x. _nz represents the refractive index in the thickness direction z of the film. d represents the thickness (nm) of the film. ]

(Knurling)
After a predetermined heat treatment or cooling treatment, it is preferable to provide a slitter and cut off the end portion before winding to obtain a good winding shape. Furthermore, it is preferable to knurling both ends of the width.

  The knurling process can be formed by pressing a heated embossing roller. Fine embossing is formed on the embossing roller, and by pressing the embossing roller, unevenness can be formed on the film and the end can be made bulky.

  The height of the knurling at both ends of the width of the substrate film according to the present invention is preferably 4 to 20 μm and the width is 5 to 20 mm.

  In the present invention, the knurling process is preferably provided after the drying process and before the winding in the film forming process.

(5-4) Winding treatment This is a treatment for winding the film as a film after the residual solvent amount is 2% by mass or less. Can be obtained.

  As a winding method, a generally used method may be used, and there are a constant torque method, a constant tension method, a taper tension method, a program tension control method with a constant internal stress, and the like.

(6) Physical properties of base film (6-1) Glass transition point The base film according to the present invention contains a carboxylic acid vinyl ester resin and other resins as described above, and thereby the glass transition point. Have at least two.

  The glass transition point is determined by using a differential scanning calorimeter (DSC-7, manufactured by Perkin Elmer) at a heating rate of 20 ° C./min, and determined in accordance with JIS K7121 (1987). Tmg).

  Having at least two glass transition points means that two or more Tg peaks indicating glass transition points appear in the differential thermal analysis result obtained by the measurement by the differential scanning calorimeter.

  Since the base film is configured in this manner, the base film can exhibit the properties of the carboxylic acid vinyl ester resin and other resins, respectively, during the stretching process of the carboxylic acid vinyl ester resin. It is possible to achieve both handleability and other resin properties.

FIG. 1 is a diagram schematically showing the results of differential thermal analysis using a differential scanning calorimeter. In the differential thermal analysis result shown in FIG. 1, two Tg peaks T1 and T2 appear and have at least two glass transition points.
In this invention, it is preferable that the highest glass transition point is 90 degreeC or more among the at least 2 or more glass transition points of a base film. For example, in FIG. 1, it is preferable that the Tg peak T2 appears at 90 ° C. or higher. Thereby, the rigidity of a base film is improved and the folding at the time of conveyance can be suppressed further effectively.
Also. In this invention, it is preferable that the temperature difference of the highest glass transition point and the lowest glass transition point is 30 degreeC or more among the at least 2 or more glass transition points of a base film. For example, in FIG. 1, the difference d between the Tg peaks T1 and T2 is preferably 30 ° C. or more. Thereby, affinity with a base film and a hydrophilic polymer layer can be improved, and light distribution nonuniformity can be reduced.

(6-2) Haze The base film according to the present invention preferably has a haze of less than 1%, more preferably less than 0.5%. By making haze less than 1%, there exists an advantage that the transparency of a base film becomes higher.

(6-3) Equilibrium moisture content In the substrate film according to the present invention, the equilibrium moisture content at 25 ° C and a relative humidity of 60% is preferably 4% or less, and more preferably 3% or less. By setting the equilibrium moisture content to 4% or less, it is preferable to easily cope with a change in humidity and to hardly change the optical characteristics and dimensions.

(6-4) Film Length, Width, Film Thickness The base film according to the present invention is preferably long, specifically, preferably about 100 to 10,000 m in length, and in a roll shape. It is wound up. Moreover, it is preferable that the width | variety of the base film which concerns on this invention is 1 m or more, More preferably, it is 1.4 m or more, and it is preferable that it is especially 1.4-4 m.

The thickness of the base film after the stretching step described below is preferably in the range of 10 to 60 μm from the viewpoint of thinning and productivity of the polarizing laminated film. When the thickness is 10 μm or more, a certain level of film strength and retardation can be exhibited. If thickness is 60 micrometers or less, it will comprise a desired phase difference and can contribute to thickness reduction of a light-polarizing laminated film. Preferably, it exists in the range of 20-50 micrometers.
In addition, when performing the extending | stretching process mentioned later several times, it is preferable that the thickness after performing all the extending processes is the said range.

《Polarizer》
The polarizer is obtained by stretching a hydrophilic polymer layer containing a hydrophilic polymer and dyeing it with a dichroic substance. The stretching and dyeing performed on the hydrophilic polymer layer can form a polarizer regardless of which is performed first. As the hydrophilic polymer contained in the hydrophilic polymer layer, for example, a polyvinyl alcohol resin (hereinafter also referred to as “PVA resin”) is preferably used. As the PVA resin, a saponified polyvinyl acetate resin can be used. Examples of the polyvinyl acetate resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers with other monomers copolymerizable with 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 PVA resin is 99.0 mol% or less. In the present invention, the reason for using a PVA resin having a saponification degree of 99.0 mol% or less is that a constant dyeing speed can be maintained even when uniaxial stretching exceeding 5 times is performed. There is an advantage that a thin polarizing laminated film having high performance can be efficiently produced. On the other hand, when a PVA resin having a saponification degree exceeding 99.0 mol% is used, the dyeing speed is remarkably slow, and a polarizer having sufficient polarization performance may not be obtained. There may be a problem that takes several times longer.

  The degree of saponification of the PVA resin is preferably 90 mol% or more, and more preferably 94 mol% or more. If the saponification degree is less than 90 mol%, the strength such as water resistance may not be sufficient.

The saponification degree as used herein is a unit ratio (mol%) of the ratio of the acetate group contained in the polyvinyl acetate resin, which is the raw material of the PVA resin, to the hydroxyl group by the saponification step. A numeric value defined by an expression. It can be determined by the method defined in JIS K 6726 (1994).
Saponification degree (mol%) = (number of hydroxyl groups) ÷ (number of hydroxyl groups + number of acetate groups) × 100

  The higher the degree of saponification, the higher the proportion of hydroxyl groups, that is, the lower the proportion of acetate groups that inhibit crystallization. The PVA resin used in the present invention is not particularly limited as long as the saponification degree is 99.0 mol% or less, and may be modified polyvinyl alcohol partially modified. For example, the PVA resin may be modified with olefins such as ethylene and propylene, unsaturated carboxylic acids such as acrylic acid, methacrylic acid and crotonic acid, alkyl esters of unsaturated carboxylic acids, acrylamide, etc. The average degree of polymerization of the PVA resin is not particularly limited, but is preferably 100 to 10,000, and more preferably 1500 to 10,000.

  Examples of the PVA resin having such characteristics include PVA124 (saponification degree: 98.0 to 99.0 mol%) and PVA117 (degree of saponification: 98.0 to 99.0 mol%) manufactured by Kuraray Co., Ltd. ), PVA624 (degree of saponification: 95.0-96.0 mol%) and PVA617 (degree of saponification: 94.5-95.5 mol%); for example, AH-26 (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) Degree of saponification: 97.0 to 98.8 mol%), AH-22 (degree of saponification: 97.5 to 98.5 mol%), NH-18 (degree of saponification: 98.0 to 99.0 mol%) %) And N-300 (degree of saponification: 98.0 to 99.0 mol%); for example, JF-17 (saponification degree: 98.0 to 99.0 mol%) of Nippon Vinegar Pival Co., Ltd. , JF-17L (degree of saponification: 98.0-99.0 mol%) and JF-20 (degree of saponification: 8.0 to 99.0 mol%), and the like, can be suitably used in the present invention.

  The polarizer is preferably uniaxially stretched at a stretch ratio of more than 5 times, more preferably more than 5 times and not more than 17 times.

  In the polarizer, a dichroic substance is adsorbed and oriented on the PVA resin as described above. The thickness of the polarizer is 10 μm or less, preferably 7 μm or less. By setting the thickness of the polarizer to 10 μm or less, a thin polarizing laminated film can be configured.

<Other optical layers>
The polarizing laminated film of the present invention configured as described above can be used as a polarizing laminated film in which other optical layers are laminated in practical use. Moreover, the said base film may have a function of these optical layers. Examples of other optical layers include a reflective polarizing film that transmits certain types of polarized light and reflects polarized light that exhibits the opposite properties, a film with an antiglare function having an uneven shape on the surface, and a surface antireflection function. Examples thereof include an attached film, a reflective film having a reflective function on the surface, a transflective film having both a reflective function and a transmissive function, and a viewing angle compensation film.

  Commercially available products corresponding to reflective polarizing films that transmit certain types of polarized light and reflect polarized light that exhibits the opposite properties include DBEF (available from 3M, Sumitomo 3M Co., Ltd.), APF (Available from 3M, available from Sumitomo 3M Limited). Examples of the viewing angle compensation film include an optical compensation film coated with a liquid crystal compound on the surface of the substrate and oriented, a retardation film made of a polycarbonate resin, and a retardation film made of a cyclic polyolefin resin. Commercially available products corresponding to the optical compensation film in which a liquid crystal compound is coated on the substrate surface and oriented include WV film (manufactured by FUJIFILM Corporation), NH film (manufactured by Nippon Oil Corporation), NR Examples include films (manufactured by Nippon Oil Corporation). Commercial products corresponding to retardation films made of cyclic polyolefin resins include Arton (registered trademark) film (manufactured by JSR Corporation), Essina (registered trademark) (manufactured by Sekisui Chemical Co., Ltd.), Zeonor ( Registered trademark) film (manufactured by Nippon Zeon Co., Ltd.).

<< Method for producing polarizing laminated film >>
The method for producing a polarizing laminated film of the present invention comprises two or more kinds of resins including at least a carboxylic acid vinyl ester resin, and is successively applied or coextruded on a base film having at least two glass transition points. A step of forming a hydrophilic polymer layer containing a hydrophilic polymer (hydrophilic polymer layer forming step), a step of stretching a laminated film (stretching step), and a hydrophilic polymer layer as a dichroic substance And a step of dyeing by dyeing (dyeing step).

  In the production method of the present invention, the stretching step and the dyeing step may not be performed in this order. That is, a dyeing process may be performed after the hydrophilic polymer layer forming process, and a stretching process may be performed thereafter. Moreover, as described later, the production method of the present invention may further include steps other than the hydrophilic polymer layer forming step, the stretching step, and the dyeing step.

  The polarizing laminate film of the present invention has a base film on one surface of a hydrophilic polymer layer (polarizer). The base film can be used as it is as a polarizing plate protective film, and can be used as a polarizing plate by bonding the polarizing plate protective film to the surface of the polarizer that is not in contact with the base film. Moreover, a hydrophilic polymer layer may be peeled from a base film, and a polarizing plate protective film may be bonded on both surfaces of the hydrophilic polymer layer to be used as a polarizing plate.

[1] Hydrophilic polymer layer forming step First, a hydrophilic polymer layer forming step in which a hydrophilic polymer layer containing a hydrophilic polymer is formed on the substrate film by sequential coating or coextrusion. I do.

  The hydrophilic polymer layer can be obtained, for example, by applying a coating solution containing the PVA resin on a substrate film and drying (sequential application).

  The coating solution is typically a solution obtained by dissolving the PVA resin in a solvent. Examples of the solvent include water, dimethyl sulfoxide, dimethylformamide, dimethylacetamide N-methylpyrrolidone, various glycols, polyhydric alcohols such as trimethylolpropane, and amines such as ethylenediamine and diethylenetriamine. These may be used alone or in combination of two or more. Among these, water is preferable. The PVA resin concentration of the solution is preferably 3 to 20 parts by mass with respect to 100 parts by mass of the solvent. If it is such resin concentration, the uniform coating film closely_contact | adhered to the base film can be formed.

  You may mix | blend an additive with a coating liquid. Examples of the additive include a plasticizer and a surfactant. Examples of the plasticizer include polyhydric alcohols such as ethylene glycol and glycerin. Examples of the surfactant include nonionic surfactants. These can be used for the purpose of further improving the uniformity, dyeability and stretchability of the resulting PVA resin layer.

  Any appropriate method can be adopted as a coating method of the coating solution. Examples thereof include a roll coating method, a spin coating method, a wire bar coating method, a dip coating method, a die coating method, a curtain coating method, a spray coating method, a knife coating method (comma coating method, etc.).

  The drying temperature is preferably TgH ° C or lower, more preferably (TgH-10) ° C or lower, when Tg having the highest glass transition point (Tg) of the substrate film is TgH. By drying in such a temperature range, the base film is prevented from being deformed before the hydrophilic polymer layer is formed, and the orientation of the resulting hydrophilic polymer layer is prevented from deteriorating. be able to. Thus, the base film can be deformed well together with the hydrophilic polymer layer, and stretching described later can be performed satisfactorily. As a result, a good orientation can be imparted to the hydrophilic polymer layer, and a thin polarizing plate having excellent optical properties can be obtained. Here, “orientation” means the orientation of the molecular chain of the PVA resin layer.

  In addition, the laminated film according to the present invention can be formed, for example, by co-extrusion of a base film forming material and a hydrophilic polymer layer forming material. By such coextrusion, a laminated film in which the base film and the hydrophilic polymer layer are integrated is obtained. In co-extrusion, the material of the base film and the material of the hydrophilic polymer layer are charged into the co-extrusion machine as a forming material for each layer, and the thickness of the base film and the hydrophilic polymer layer to be co-extruded is It is preferable to control to be within the above range.

  The layer thickness of the hydrophilic polymer layer to be formed is preferably more than 3 μm and not more than 30 μm, and more preferably 5 to 20 μm. If it is 3 μm or less, it becomes too thin after stretching and the dyeability is remarkably deteriorated. If it exceeds 30 μm, the thickness of the finally obtained polarizer may exceed 10 μm, which is not preferable.

  In addition, before forming a hydrophilic polymer layer on a base film, in order to further improve the applicability of the base film and the hydrophilic polymer layer (polarizer), the hydrophilic polymer of the base film is used. For example, corona treatment, plasma treatment, flame treatment, or the like may be performed on the surface on which the layer is formed.

[2] Stretching step In the stretching step, the laminated film composed of the base film and the hydrophilic polymer layer is uniaxial so that the draw ratio is 1.01-17.0 times the original length of the laminated film. It is preferable to stretch to obtain a stretched film. Preferably, it is uniaxially stretched so that the draw ratio is more than 4.0 times and less than 17.0 times, more preferably more than 5.0 times and less than 8.0 times. When the draw ratio is 5 times or more, the hydrophilic polymer layer made of PVA resin is more fully oriented, and as a result, the degree of polarization of the polarizer can be made sufficiently higher. Moreover, when the draw ratio is set to 17 times or less, the laminated film is less likely to break during stretching, and at the same time, the stretched film is prevented from becoming unnecessarily thin, and the workability and handling properties in the subsequent process are reduced. Can be improved. The stretching process in the stretching process is not limited to stretching in one stage, and can be performed in multiple stages. When performing in multiple stages, the stretching process is performed so that the stretching ratio is the same for all stretching processes.

  In the stretching step, a longitudinal stretching process performed in the longitudinal direction of the laminated film is preferable, but when the polarization performance is not required so much, it may be fixed-end uniaxial stretching typified by transverse uniaxial stretching by the tenter method. Absent. Examples of the longitudinal stretching method include an inter-roll stretching method, a compression stretching method, and a stretching method using a tenter. The stretching process is not limited to the longitudinal stretching process, and may be an oblique stretching process or the like. Moreover, it is preferable that it is free end uniaxial stretching.

  In addition, as the stretching treatment, either a wet stretching method or a dry stretching method can be adopted, but the use of the dry stretching method is preferable in that the temperature for stretching the laminated film can be selected from a wide range.

  Usually, the stretching temperature is preferably in the range of Tg to Tg + 50 ° C. of the resin constituting the base film, and more preferably in the range of Tg to Tg + 40 ° C. In the present invention, The temperature is preferably between at least two glass transition points. That is, when the substrate film has two glass transition points, the temperature is between the two glass transition points. When the substrate film has three or more glass transition points, the most Between the high glass transition point and the lowest glass transition point. Thereby, the conveyance property after an extending process can be made favorable.

(Wet stretching)
In the present invention, in the stretching step, the laminated film may be stretched in water (hereinafter also referred to as “wet stretching”).

  Arbitrary appropriate methods can be employ | adopted as the extending | stretching method in wet extending | stretching. Specifically, it may be fixed end stretching or free end stretching (for example, a method of uniaxial stretching through a laminated film between rolls having different peripheral speeds). The stretching of the laminated film may be performed in one stage or in multiple stages. When performed in multiple stages, the draw ratio described below is the product of the draw ratios at each stage.

  The wet stretching may be performed, for example, by immersing the laminated film in pure water, distilled water, ion-exchanged water, tap water, or the like, but is preferably performed by immersing the laminated film in an aqueous boric acid solution (boron). Wet stretching in acid water). By using an aqueous boric acid solution as the stretching bath, the hydrophilic polymer layer containing the PVA resin can be provided with rigidity that can withstand the tension applied during stretching and water resistance that does not dissolve in water. Specifically, boric acid can form a tetrahydroxyborate anion in an aqueous solution and crosslink with the PVA resin by hydrogen bonding. As a result, rigidity and water resistance can be imparted to the PVA resin, the film can be stretched satisfactorily, and a polarizing laminated film having excellent optical properties (for example, the degree of polarization) can be produced.

  The boric acid aqueous solution is preferably obtained by dissolving boric acid and / or borate in water as a solvent. The boric acid concentration is preferably 1 to 10 parts by mass with respect to 100 parts by mass of water. By setting the boric acid concentration to 1 part by mass or more, dissolution of the PVA resin can be effectively suppressed, and a polarizing laminate film having higher characteristics can be produced. In addition to boric acid or borate, an aqueous solution obtained by dissolving a boron compound such as borax, glyoxal, glutaraldehyde, or the like in a solvent can also be used.

  When a dichroic substance (typically iodine) is adsorbed to the hydrophilic polymer layer in advance by a dyeing process described later, preferably, an iodide is blended in the stretching bath (boric acid aqueous solution). By blending iodide, elution of iodine adsorbed on the hydrophilic polymer layer can be suppressed. 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. Etc. Among these, potassium iodide is preferable. The concentration of iodide is preferably 0.05 to 15 parts by mass, more preferably 0.5 to 8 parts by mass with respect to 100 parts by mass of water.

The stretching temperature in the wet stretching (liquid temperature of the stretching bath) is preferably 40 to 85 ° C, more preferably 50 to 85 ° C. If it is such temperature, it can extend | stretch at high magnification, suppressing melt | dissolution of PVA resin contained in a hydrophilic polymer layer. On the other hand, the higher the temperature of the stretching bath, the higher the solubility of the PVA resin, and there is a possibility that excellent optical properties cannot be obtained. The immersion time of the laminated film in the stretching bath is preferably 15 seconds to 5 minutes.
The draw ratio in wet drawing is about 1.01 to 8.0 times, preferably about 5.0 to 8.0 times.

[3] Dyeing step In the dyeing step, the hydrophilic polymer layer of the laminated film is dyed with a dichroic substance. Examples of the dichroic substance include iodine and organic dyes. Examples of organic dyes include Red BR, Red LR, Red R, Pink LB, Rubin BL, Bordeaux GS, Sky Blue LG, Lemon Yellow, Blue BR, Blue 2R, Navy RY, Green LG, Violet LB, Violet B, Black H, Black B, Black GSP, Yellow 3G, Yellow R, Orange LR, Orange 3R, Scarlet GL, Scarlet KGL, Congo Red, Brilliant Violet BK, Spura Blue G, Spura Blue GL, Spura Orange GL, Direct Sky Blue, Direct First Orange S, First Black, etc. can be used. One kind of these dichroic substances may be used, or two or more kinds may be used in combination.

  A dyeing process is performed by immersing the whole laminated film in a solution (dyeing solution) containing the above-mentioned dichroic substance, for example. As the staining solution, a solution in which the above dichroic substance is dissolved in a solvent can be used. As a solvent for the dyeing solution, water is generally used, but an organic solvent compatible with water may be further added. The concentration of the dichroic substance is preferably 0.01 to 10% by mass, more preferably 0.02 to 7% by mass, and particularly preferably 0.025 to 5% by mass.

  When iodine is used as the dichroic substance, it is preferable to further add an iodide because the dyeing efficiency can be further improved. 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 iodide. Examples include titanium. The addition ratio of these iodides is preferably 0.01 to 10% by mass in the dyeing solution. Of the iodides, it is preferable to add potassium iodide. When adding potassium iodide, the ratio of iodine to potassium iodide is preferably in the range of 1: 5 to 1: 100, more preferably in the range of 1: 6 to 1:80, by mass ratio. , Particularly preferably in the range of 1: 7 to 1:70.

  The immersion time of the laminated film in the dyeing solution is not particularly limited, but usually it is preferably in the range of 15 seconds to 15 minutes, more preferably 1 to 3 minutes. Moreover, it is preferable that it is in the range of 10-60 degreeC, and, as for the temperature of a dyeing | staining solution, it is more preferable that it exists in the range of 20-40 degreeC.

[4] Other steps In the method for producing a polarizing laminate film of the present invention, other steps may be included in addition to the above-described lamination step, stretching step and dyeing step. Examples of other processes include an air stretching process different from the stretching process, an insolubilization process, a crosslinking process, a washing process, and a drying process. The other steps can be performed at any appropriate timing.

(Air stretch process)
When the stretching process is performed after the dyeing process and the wet stretching is performed in the boric acid aqueous solution in the stretching process, the method for producing the polarizing laminated film of the present invention is performed before the dyeing process. It is preferable to have an air stretching step of stretching the film in the air.

  In the aerial stretching step, when the laminated film formed in the laminating step has TgL as the lowest Tg among the two or more glass transition points (Tg) of the base film according to the present invention, (TgL + 15) Stretch in the air above ℃. Such an air stretching process can be positioned as a preliminary or auxiliary stretching for wet stretching in an aqueous boric acid solution.

  By performing an air stretching process, the laminated film may be stretched at a higher magnification. As a result, it is possible to produce a polarizing laminated film having more excellent optical properties (for example, the degree of polarization). By performing air stretching, the film can be stretched while suppressing the orientation of the base film. As the orientation of the substrate film is improved, the stretching tension increases, so that stable stretching becomes difficult or the substrate film is broken. Therefore, the laminated film can be stretched at a higher magnification by stretching while suppressing the orientation of the base film.

  Moreover, the orientation of PVA resin can be improved by combining in-air stretching, and thereby the orientation of PVA resin can be improved even after wet stretching in a boric acid solution. Specifically, by previously improving the orientation of the PVA resin by stretching in the air, the PVA resin is easily cross-linked with boric acid during wet stretching in a boric acid aqueous solution, and boric acid is a nodal point. It is presumed that the orientation of the PVA resin is increased even after wet stretching by being stretched in this state. As a result, a polarizing laminated film having excellent optical characteristics (for example, the degree of polarization) can be produced.

  The stretching method in the air stretching step may be the above stretching step, fixed end stretching, or free end stretching (for example, a method of uniaxial stretching through a laminate between rolls having different peripheral speeds). In addition, the stretching may be performed in one stage or in multiple stages. When performed in multiple stages, the draw ratio described below is the product of the draw ratios at each stage. The stretching direction in this step is preferably substantially the same as the stretching direction in the stretching step.

  The draw ratio in the air drawing is preferably 3.5 times or less.

(Crosslinking process)
The manufacturing method of the light-polarizing laminated film of this invention is good also as what has a bridge | crosslinking process. By performing the crosslinking treatment, water resistance can be imparted to the hydrophilic polymer layer. The crosslinking step is preferably performed before the stretching step, and when the stretching step is performed after the dyeing step, it is preferably performed after the dyeing step and before the stretching step.

The crosslinking treatment can be performed, for example, by immersing the laminated film in a solution containing a crosslinking agent (crosslinking solution).
Conventionally known substances can be used as the crosslinking agent. Examples thereof include boron compounds such as boric acid and borax, glyoxal, and glutaraldehyde. One kind of these may be used, or two or more kinds may be used in combination.

  As the crosslinking solution, a solution in which a crosslinking agent is dissolved in a solvent can be used. As the solvent, for example, water can be used, but an organic solvent compatible with water may be further included. Although the density | concentration of the crosslinking agent in a crosslinking solution is not limited to this, It is preferable to exist in the range of 1-20 mass%, and it is more preferable that it is 6-15 mass%.

  Iodide may be added to the crosslinking solution. By adding iodide, the in-plane polarization characteristics of the hydrophilic polymer layer can be made more uniform. Addition of iodide is particularly preferable when a crosslinking step is performed after the dyeing step. By adding iodide, elution of iodine adsorbed on the hydrophilic polymer layer can be suppressed. 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. Is mentioned. The iodide content is 0.05 to 15% by mass, more preferably 0.5 to 8% by mass.

  The immersion time of the laminated film in the crosslinking solution is usually preferably from 15 seconds to 20 minutes, and more preferably from 30 seconds to 15 minutes. Moreover, it is preferable that the temperature of a crosslinking solution exists in the range of 10-80 degreeC.

(Washing process)
In the manufacturing method of the light-polarizing laminated film of this invention, it is preferable to perform a washing | cleaning process after the said extending process and dyeing | staining process. As the cleaning step, water cleaning treatment can be performed. The water washing treatment can be usually performed by immersing the stretched and dyed laminated film in pure water such as ion exchange water or distilled water. The water washing temperature is usually in the range of 3 to 50 ° C, preferably 4 to 20 ° C. The immersion time is usually 2 to 300 seconds, preferably 3 to 240 seconds.

  The washing step may be a combination of a washing treatment with an iodide solution and a water washing treatment, and a solution appropriately mixed with a liquid alcohol such as methanol, ethanol, isopropyl alcohol, butanol, or propanol can also be used.

(Drying process)
In the manufacturing method of the polarizing laminated film of this invention, it is preferable to perform a drying process after a washing | cleaning process. Any appropriate method (for example, natural drying, air drying, heat drying) can be adopted as the drying step. For example, the drying temperature in the case of heat drying is preferably TgH ° C. or less, more preferably (TgH ° C. or less), where TgH is the highest Tg of two or more glass transition points (Tg) of the base film. TgH-10) ° C. or lower.

  In the drying step, the laminated film may be stretched while being dried. By stretching while drying, the laminate can be further contracted (necked in) in a direction substantially orthogonal to the stretching direction (for example, the width direction), and the orientation of the hydrophilic polymer layer can be further enhanced. As a result, the orientation of the iodine complex of the hydrophilic polymer layer can be improved, and a polarizing laminated film having extremely excellent optical properties (for example, the degree of polarization) can be produced.

  The stretching method in the drying step may be fixed end stretching or free end stretching (for example, a method of uniaxial stretching through a laminate between rolls having different peripheral speeds). In addition, the stretching may be performed in one stage or in multiple stages. When performed in multiple stages, the draw ratio described below is the product of the draw ratios at each stage. The stretching direction in this step is preferably substantially the same as the stretching direction in the stretching step.

  The free end stretching generally means a stretching method in which stretching is performed only in one direction. Here, when the film is stretched in one direction, the film may shrink in a direction substantially perpendicular to the stretching direction. A method of stretching without suppressing this shrinkage is called free end stretching. On the other hand, a method of stretching while suppressing shrinkage of the film in a direction substantially perpendicular to the stretching direction is usually referred to as fixed end stretching. Examples of the fixed end stretching method include a method of shortening the distance between rolls in a roll stretching using a transport roll and stretching in the transport direction, and a film end in a direction substantially perpendicular to the transport direction (width direction). The method of extending | stretching in a conveyance direction in the state fixed by the chuck | zipper etc. of the extending machine is mentioned. These methods can control the shrinkage rate in the width direction. Specifically, in roll stretching, the amount of shrinkage can be reduced as the distance between the rolls is shortened, and the amount of shrinkage is increased as the distance between the rolls is increased, and approaches the shrinkage amount of free end stretching. When the film end is fixed with a chuck and stretched, the shrinkage rate in the width direction can be controlled by appropriately narrowing the width of the chuck simultaneously with stretching.

  The drying temperature (stretching temperature) is preferably (TgL + 15) ° C. or higher, where TgL is the lowest Tg of the two or more glass transition points (Tg) of the base film according to the present invention.

  The draw ratio in the drying step is preferably 1.01 to 1.5 times, more preferably 1.01 to 1.25 times.

<< Polarizing plate manufacturing method >>
The manufacturing method of the polarizing plate of this invention is the process of bonding a polarizing plate protective film on the at least one surface of the polarizer of the said polarizing laminated film following the process of manufacturing a polarizing laminated film as mentioned above. Have

  As a manufacturing method of the light-polarizing laminated film of the present invention, a base film in contact with one surface of a polarizer is used as it is as a polarizing plate protective film, and a polarizing plate is formed on the surface not in contact with the base film of the polarizer. It can be used as a polarizing plate by bonding a protective film. Moreover, after peeling a base film from a light-polarizing laminated film, even if it uses a polarizing plate protective film on the surface which the base film of the polarizer was in contact with, preferably both surfaces of a polarizer, it may be used as a polarizing plate. good.

As the polarizing plate protective film used in the method for producing the polarizing plate of the present invention, a conventionally known polarizing plate protective film is used. For example, from the visibility of the polarizing plate and ease of handling, polymers such as cellulose ester are used. It is preferable to consist of a film.
The thickness of such a polarizing plate protective film is preferably 15 to 65 μm, more preferably 18 to 40 μm, and most preferably 20 to 35 μm from the viewpoint of thinning the polarizing plate and the strength of the polarizing plate.

  Hereinafter, the manufacturing method of a polarizing plate is demonstrated more concretely.

  A polarizing plate can be manufactured by laminating the above-described polarizing plate protective film on one surface of a polarizer using a photocurable adhesive. When adhesiveness differs on both surfaces of a polarizing plate protective film, it is preferable to bond the one with good adhesiveness.

  The polarizing plate has the following photo-curing adhesive on at least one of the pretreatment step for easily bonding the surface of the polarizing plate protective film to which the polarizer is bonded, and the bonding surface of the polarizer and the polarizing plate protective film. Adhesive application process to apply, polarizer and polarizing plate protective film are bonded and bonded through the adhesive layer, and the polarizer and polarizing plate protective film are bonded through the adhesive layer It can manufacture by the manufacturing method including the hardening process which hardens an adhesive bond layer in the state made.

  In the pretreatment step, an easy adhesion treatment is performed on the adhesion surface of the polarizing plate protective film with the polarizer. When the polarizing plate protective film and the retardation film are bonded to both surfaces of the polarizer, easy adhesion treatment is performed on the respective polarizing plate protective film and the retardation film. In the next adhesive application process, the surface subjected to the easy adhesion treatment is treated as a bonding surface with the polarizer, and therefore, the surface to be bonded to the photocurable resin layer is easily applied to both surfaces of the polarizing plate protective film. Apply adhesive treatment.

  In the adhesive application step, a photocurable adhesive is applied to at least one of the adhesive surfaces of the polarizer and the polarizing plate protective film. When applying a photocurable adhesive directly on the surface of a polarizer or a polarizing plate protective film, the coating method is not particularly limited. For example, various wet coating methods such as a doctor blade, a wire bar, a die coater, a comma coater, and a gravure coater can be used. Moreover, after casting a photocurable adhesive between a polarizer and a polarizing plate protective film, the method of pressurizing with a roll etc. and spreading it uniformly can also be utilized.

  After apply | coating a photocurable adhesive agent by said method, a bonding process is performed. In this bonding step, for example, when a photocurable adhesive is applied to the surface of the polarizer in the previous application step, a polarizing plate protective film is superimposed thereon. When a photocurable adhesive is applied to the surface of the polarizing plate protective film in the previous application step, a polarizer is superimposed thereon. Moreover, when a photocurable adhesive agent is cast between a polarizer and a polarizing plate protective film, a polarizer and a polarizing plate protective film are piled up in that state. In the case where a polarizing plate protective film and a retardation film are bonded to both surfaces of a polarizer, and both surfaces use a photocurable adhesive, the polarizing plates are respectively bonded to both surfaces of the polarizer via a photocurable adhesive. A protective film and a retardation film are overlaid. Usually, in this state, both sides (when a polarizing plate protective film is superimposed on one side of the polarizer, the polarizing plate protective film and the retardation film are provided on both sides of the polarizer and the polarizing plate protective film side. In the case of superimposing, pressure is applied between the polarizing plate protective film and the retardation film side of the both surfaces with a roll or the like. As the material of the roll, metal, rubber or the like can be used. The rolls arranged on both sides may be the same material or different materials.

  In the curing process, an uncured photocurable adhesive is irradiated with active energy rays, and a cationic polymerizable compound (for example, an epoxy compound or an oxetane compound) or a radical polymerizable compound (for example, an acrylate compound, an acrylamide compound, etc.) ) Is cured, and the polarizer and the polarizing plate protective film, or the polarizer and the retardation film, which are overlapped with each other through the photocurable adhesive, are bonded. When bonding a polarizing plate protective film to the single side | surface of a polarizer, you may irradiate an active energy ray from either a polarizer side or a polarizing plate protective film side. In addition, when laminating a polarizing plate protective film and a retardation film on both sides of the polarizer, in a state where the polarizing plate protective film and the retardation film are superimposed on each side of the polarizer via a photocurable adhesive, It is advantageous to irradiate active energy rays and simultaneously cure the photocurable adhesive on both sides.

  Visible light, ultraviolet rays, X-rays, electron beams, etc. can be used as the active energy rays applied for curing, but electron beams and ultraviolet rays are generally preferred because they are easy to handle and have a sufficient curing rate. Used.

  Any appropriate condition can be adopted as the electron beam irradiation condition as long as the adhesive can be cured. For example, in the electron beam irradiation, the acceleration voltage is preferably 5 to 300 kV, more preferably 10 to 250 kV. When the acceleration voltage is 5 kV or more, curing is not insufficient, and when the acceleration voltage is within 300 kV, the polarizer is not damaged. The irradiation dose is 5 to 100 kGy, more preferably 10 to 75 kGy.

Arbitrary appropriate conditions can be employ | adopted for the irradiation conditions of an ultraviolet-ray, if it is the conditions which can harden the said adhesive agent. The dose of ultraviolet rays is preferably from 50~1500mJ / cm ² in accumulated light quantity, and even more preferably 100 to 500 mJ / cm ^2.

  When performing the said manufacturing method by a continuous line, although it depends on the hardening time of an adhesive agent, Preferably it is 1-500 m / min, More preferably, it is 5-300 m / min, More preferably, it is 10-100 m / min. When the line speed is too low, productivity is poor, or damage to the polarizing plate protective film is too large, and a polarizing plate that can withstand a durability test or the like cannot be produced. When the line speed is too high, the adhesive is not sufficiently cured, and the target adhesiveness may not be obtained.

  In the polarizing plate obtained as described above, the thickness of the adhesive layer is not particularly limited, but is usually 0.01 to 10 μm, preferably 0.5 to 5 μm.

  In addition, as a manufacturing method of the polarizing plate of this invention, it is not restricted to using the above-mentioned photocurable adhesive agent, The following method may be employ | adopted.

  That is, the polarizer side of the polarizing plate protective film is alkali saponified and bonded to at least one surface of a polarizer produced by immersion and stretching in an iodine solution using a completely saponified polyvinyl alcohol aqueous solution. preferable. Another polarizing plate protective film can be bonded to the other surface.

In this case, as the polarizing plate protective film, for example, KC8UX, KC5UX, KC8UY, KC4UY, KC6UA, KC4UA, KC2UA (manufactured by Konica Minolta, Inc.) and the like are preferably used.
Moreover, when using the polarizing plate which concerns on this invention for a liquid crystal display device, a retardation film can be used as a polarizing plate protective film arrange | positioned at the liquid crystal cell side.
The retardation film according to the present invention can be obtained as a commercial product. For example, as a retardation film for VA, Konica Minoltak KC8UCR3, KC8UCR4, KC8UCR5, KC4FR, KC4KR, KC4DR, KC4SR (above, Konica Minolta ( Etc.). In addition, examples of the film that can be used other than the retardation film for VA include KC4UE, KC8UE, KC4CZ (manufactured by Konica Minolta Co., Ltd.) and the like.

  In addition to the antiglare layer or the clear hard coat layer, the polarizing plate protective film used on the surface side of the display device preferably includes an antireflection layer, an antistatic layer, an antifouling layer, and a backcoat layer.

  By using the polarizing plate according to the present invention for a liquid crystal display device, various liquid crystal display devices with excellent visibility can be produced.

<< Method for manufacturing liquid crystal display device >>
The polarizing plate produced by the production method of the present invention can be preferably used for production of various devices such as a liquid crystal display device.
Manufacture of a liquid crystal display device can be performed according to a conventionally well-known method. That is, a liquid crystal display device is generally manufactured by appropriately assembling components such as a liquid crystal cell, a polarizing plate or an optical film, and an illumination system as necessary, and incorporating a drive circuit. There is no limitation in particular except the point which uses the manufacturing method of the polarizing plate of this invention, It can apply to a conventionally well-known method. As the liquid crystal cell, any type such as a TN type, STN type, π type, VA type, IPS type, or the like can be used. In particular, an IPS liquid crystal display device is preferably used.

(IPS liquid crystal display device)
In the IPS liquid crystal display device, the liquid crystal layer of the liquid crystal panel is homogeneously aligned in parallel with the substrate surface in the initial state, and the director of the liquid crystal layer is parallel to the electrode wiring direction when no voltage is applied. When the voltage is applied, the direction of the director of the liquid crystal layer shifts to the direction perpendicular to the electrode wiring direction when the voltage is applied, and the direction of the director of the liquid crystal layer is the direction of the director when no voltage is applied. In comparison, when tilted in the direction of 45 ° electrode wiring, the liquid crystal layer when the voltage is applied rotates the azimuth of the polarization by 90 ° like a half-wave plate, The azimuth angle matches and the display is white.

In general, the layer thickness of the liquid crystal layer is constant, but because it is driven in the field of portable devices such as horizontal tablet display devices and smartphones, the response speed to switching increases when the liquid crystal layer is slightly uneven. However, even if the layer thickness of the liquid crystal layer is not constant, the effect can be maximized, and the influence on the change in the layer thickness of the liquid crystal layer is small. The liquid crystal display device according to this embodiment can be preferably used for portable devices such as a tablet display device and a smartphone, in addition to being used for a large-sized liquid crystal television. Since the polarizing plate according to the present invention can be a thin film polarizing plate, it is preferably used for a portable device such as a tablet display device or a smartphone.
The details of the IPS liquid crystal cell are not particularly limited, and the present invention may of course be implemented by referring to other conventionally known technical matters (for example, JP 2010-3060 A).

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "part by mass" or "mass%" is represented.

[Example 1]
<< Preparation of Polarizing Laminate Film 1 >>
(1) Lamination process (1-1) Formation of base film First, a base film was formed by a solution casting film forming method as follows.

(Preparation of carboxylic acid vinyl ester resin (resin A))
As the resin A, a carboxylic acid vinyl ester resin was prepared by a known method.
Specifically, 1600 g of vinyl acetate, 650 g of methyl propionate, and 50 g of methyl acetate were charged into a reactor equipped with a stirrer, and after the inside of the reactor was sufficiently purged with nitrogen, the temperature was raised to 60 ° C. and 2,2′-azobis 0.233 g of isobutyronitrile and 22.4 mg (0.1 mmol) of palladium acetate were added and reacted at 60 ° C. for 4 hours. After completion of the reaction, the reactor is cooled, the reaction solution is reprecipitated with hexane, and the resulting polymer is dried with hot air at 50 ° C. and vacuum dried at 100 ° C., so that the weight average molecular weight is 80,000 and the glass transition point. (Tg) Polyvinyl acetate at 30 ° C. was obtained. The yield of the polymer was 48%.

(Preparation of dope)
The following components were put into a sealed container and completely dissolved with heating and stirring. The obtained solution was filtered at a temperature of 50 ° C. with a filter equipped with a leaf disk filter to obtain a main dope. The filter medium having a nominal filtration accuracy of 20 μm was used.

<Dope composition>
Polyvinyl acetate as resin A 10 parts by mass Polylactic acid as resin B (weight average molecular weight: 90,000, glass transition point: 57 ° C.)
90 parts by mass 2,2′-methylenebis [6- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol] (manufactured by ADEKA Corporation) as an ultraviolet absorber LA31, molecular weight 659) 2 parts by mass Dichloromethane 430 parts by mass Methanol 11 parts by mass

  In addition, the weight average molecular weights of the resin A and the resin B can be measured by gel permeation chromatography (GPC). Moreover, the glass transition point (Tg) of Resin A and Resin B was measured at a temperature rising rate of 20 ° C./min using a differential scanning calorimeter (DSC-7 manufactured by Perkin Elmer), and JIS K7121 (1987). ).

(Film formation)
The obtained dope was uniformly cast on a stainless steel band support using a belt casting apparatus under the conditions that the liquid temperature of the dope was 35 ° C. and the width was 1.95 m and the final film thickness was 170 μm. . On the stainless steel band support, the organic solvent in the obtained dope film was evaporated until the residual solvent amount reached 100% by mass to form a web, and then the web was peeled from the stainless steel band support. The obtained web was further pre-dried at 110 ° C. for 5 minutes so that the residual solvent amount was 10% by mass, and then the web was used with a tenter and 1.2 times the original width in the TD direction at 160 ° C. Stretched. The stretching speed was 300% / min.

  After stretching with a tenter, relaxation was performed at 130 ° C. for 5 minutes, and then drying was completed while the drying zone was being conveyed by a number of rollers. The drying temperature was 130 ° C. and the transport tension was 100 N / m. The obtained film was slit to 2.0 m width, 10 mm wide and 5 μm knurled at both ends of the film, wound on a core with an initial tension of 220 N / m and a final tension of 110 N / m, and an inner diameter of 15.24 cm. A base film having a thickness of 4000 m and a thickness of 174.3 μm was obtained.

(1-2) Lamination of hydrophilic polymer layer Polyvinyl alcohol powder (manufactured by Kuraray Co., Ltd., average polymerization degree 2400, saponification degree 98.0-99.0 mol%, trade name: PVA124) was heated at 95 ° C. An aqueous polyvinyl alcohol solution having a concentration of 8% by mass was prepared by dissolving in water.
Next, the surface of the base film was subjected to corona discharge treatment. The corona discharge treatment was performed at a corona output intensity of 2.0 kW and a line speed of 18 m / min. Next, the prepared aqueous solution is applied onto the base film using a lip coater on the corona discharge treatment surface of the base film, and dried at 80 ° C. for 20 minutes to form a base film and a hydrophilic polymer layer. A laminated film of layers was formed.

(2) Stretching Step Using the tenter device, 5.8 times free end uniaxial stretching was performed on the laminated film at 160 ° C. The layer thickness of the water-soluble polymer layer after stretching was 6.1 μm.

(3) Dyeing step After that, the laminated film is immersed in a 60 ° C. warm bath for 60 seconds, and immersed in a dyeing solution having the following composition which is a mixed aqueous solution of iodine and potassium iodide at 30 ° C. for about 150 seconds, followed by dyeing. Excess iodine solution was washed away with pure water at ℃. Subsequently, it was immersed for 600 seconds in the bridge | crosslinking solution of the following composition which is a 76 degreeC mixed solution of boric acid and potassium iodide. Thereafter, it was washed with pure water at 10 ° C. for 4 seconds, and finally dried at 50 ° C. for 300 seconds. Thus, the light-polarizing laminated film 1 was produced.

<Dyeing solution>
Water: 100 parts by mass Iodine: 0.6 parts by mass Potassium iodide: 10 parts by mass <Crosslinking solution>
Water: 100 parts by mass Boric acid: 9.5 parts by mass Potassium iodide: 5 parts by mass

<< Preparation of Polarizing Laminated Films 2-22 >>
In the production of the polarizing laminated film 1, the resin A and the resin B described in Table 1 are used as the material of the base film, and the resin A: the resin B has a mass composition ratio described in Table 1. Polarizing laminated films 2 to 22 were produced in the same manner except that the stretching temperature was changed to the temperature shown in Table 1.
In Table 1, MMA-St indicates a resin having a copolymerization ratio of methyl methacrylate and styrene of 50:50, and MMA-ACMO indicates a copolymerization ratio of methyl methacrylate and acryloylmorpholine is 70:30. A resin is represented, PMMA represents polymethyl methacrylate, and AS resin represents a resin having a copolymerization ratio of styrene and acrylonitrile of 70:30.

<< Preparation of Polarizing Laminated Film 23 >>
In the production of the polarizing laminated film 1, a polarizing laminated film 23 was produced in the same manner except that the base film forming method was changed to the following melt casting film forming method.

First, the following components were mixed.
<Composition of resin composition>
Polyvinyl acetate 50 parts by weight as resin A Polymethyl methacrylate: PMMA 50 parts by weight as resin B Plasticizer: Acetyltributyl citrate (ATBC) 5 parts by weight 2,2′-methylenebis [6- (2H-benzoate) as an ultraviolet absorber Triazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol] (LA31 manufactured by ADEKA Corporation, molecular weight 659) 2 parts by mass

  The obtained mixture was melt-kneaded at 235 ° C. with a twin-screw extruder and extruded into a strand shape. The resin composition extruded in a strand form was cooled with water and then cut to obtain pellets.

  The pellets obtained were dried by circulating dehumidified air at a temperature of 70 ° C. for 5 hours or more, and then put into a single screw extruder while maintaining the temperature at 100 ° C. The moisture content of the pellets charged into the single screw extruder was 120 ppm.

A film was produced by melt casting using the obtained pellets.
Specifically, the obtained pellets were melt-kneaded at 235 ° C. with a single screw extruder, and then extruded from a T-die onto a cooling roller having a surface temperature of 90 ° C. And after pressing the resin extruded on the cooling roller with the elastic touch roller whose surface metal layer thickness is 2 mm, it cooled further with two cooling rollers, and obtained the web of thickness 60 micrometers.

  After the cooled and solidified web is peeled off by a peeling roller, it is a tenter stretching machine having a preheating zone, a stretching zone, a holding zone, and a cooling zone, and further having a neutral zone between the zones. The film was stretched 5 times. Thereafter, the film was cooled until the film temperature became 30 ° C., and the clip of the tenter stretching machine was removed. And the both ends of the width direction of a film were cut off and the base film with a film thickness of 172.6 micrometers was obtained.

<< Preparation of polarizing laminated films 24 and 25 >>
In the production of the polarizing laminated film 1, polarizing laminated films 24 and 25 were produced in the same manner except that only one kind of resin listed in Table 1 was used as the material for the base film.

<< Preparation of Polarizing Laminated Film 26 >>
In the production of the polarizing laminated film 1, the polarizing laminated film 26 was produced in the same manner except that the base film was produced as follows.
Polyester raw material A (TPA as carboxylic acid unit: 91 mol% + IPA: 9 mol%, EG as glycol unit: 84 mol% + CHDM: 16 mol%, IV = 0.73 dl / g) having an average particle size of 4.2 μm A mixture containing 0.1% by mass of amorphous silica was supplied to an extruder, melted at 280 ° C., extruded onto a casting drum, and rapidly solidified by applying an electrostatic application method to obtain an unstretched sheet. . The obtained sheet was stretched 3.6 times in the machine direction at 78 ° C. in the longitudinal direction, further stretched 3.8 times in the transverse direction at 85 ° C., heated stepwise and then heat treated at 181 ° C. for 3 seconds, Heat treatment relaxation (to narrow the tenter rail width) by 18% in the direction. Finally, a substrate film made of PET (Polyethylene Terephthalate) having a thickness of 75 μm was obtained.

<< Preparation of Polarizing Laminated Film 27 >>
In the production of the polarizing laminated film 1, the polarizing laminated film 27 was produced in the same manner except that the base film was produced as follows.
After feeding 100 parts by mass of a propylene / ethylene copolymer (ethylene content = 0.4% by mass, MFR = 9 g / 10 min), which is a polypropylene resin, to a 50 mmφ extruder heated to 275 ° C. from a hopper, this extruder Next, melted and kneaded in a 600mm wide T-die, extruded into a sheet form in a molten state, brought into contact with a cooling roll adjusted to 38 ° C, and cooled by blowing air from an air chamber to obtain a film having a thickness of 75 µm It was. This propylene-based resin film was wound up by 1800 m by the upper winding method so that the air blowing surface was inside. Then, after about 1 hour under the temperature condition of 23 ° C., it is installed in a slitter feeding machine, fed out by the lowering method, and the winding film roll is placed so that the air blowing surface is outside by the upper winding method. Formed and stored at room temperature for 2 days. In this way, a base film made of PP (Polypropylene) wound up so that the air blowing surface was on the outside was obtained.

<< Evaluation of Polarizing Laminated Films 1-27 >>
The following evaluation was performed about the polarizing laminated films 1-27 produced as mentioned above. The evaluation results are shown in Table 1. In addition, when the polarization degree of the polarizing laminated films 1-27 was measured using the ultraviolet visible spectrophotometer (The product name "V7100" by JASCO Corporation), all were 99.95% or more.

(1) Applicability After the lamination of the hydrophilic polymer layer, before the stretching step, the film thickness at a plurality of locations of the laminated film is determined according to J.J. A. Woollam Co. Inc. It measured with the VB-250 type | mold VASE ellipsometer made, and the measurement result was evaluated on the following reference | standard.
◎: A coating film is uniformly formed on the entire surface, and the film thickness error is within 10%. ○: The coating film is uniformly formed on the entire surface, and the film thickness error is also within 20%. There is a part where the thickness error is 20% or more.

(2) Folding at the time of conveyance The produced polarizing laminated films 1-27 were roll-conveyed, the change of each polarizing laminated film by continuous conveyance was confirmed visually, and the confirmation result was evaluated on the following reference | standard.
○: Continuous curling with almost no curling ○ △: Curling occurred while transporting, but continuous transporting △: Folding of 1cm edge occurred due to curling, but continuous transporting ×: Folding due to curling Could not be continuously conveyed.

<< Production of Polarizing Plates 1-1 to 1-25 >>
Subsequently, polarizing plates 1-1 to 1-25 were produced using the produced polarizing laminated films 1 to 23, 25, and 26. Specifically, the base film is peeled from the produced polarizing laminated films 1 to 23, 25, and 26, and polarizing plate protective films 1 and 2 obtained as described below are formed on both sides of the obtained polarizer. By laminating, polarizing plates 1-1 to 1-25 were produced.

(1) Production of polarizing plate protective film 1 (synthesis of polycondensed ester compound P1)
251 g of 1,2-propylene glycol, 244 g of phthalic anhydride, 103 g of adipic acid, 610 g of benzoic acid, 0.191 g of tetraisopropyl titanate as an esterification catalyst, 2 L four-neck equipped with thermometer, stirrer, and slow cooling tube The flask is charged and gradually heated with stirring until it reaches 230 ° C. in a nitrogen stream. The dehydration condensation reaction was carried out while observing the degree of polymerization. After completion of the reaction, unreacted 1,2-propylene glycol was distilled off under reduced pressure at 200 ° C. to obtain a polycondensed ester compound P1. The acid value was 0.10 and the number average molecular weight was 450.

(Synthesis of polycondensed ester compound P2)
251 g of 1,2-propylene glycol, 354 g of terephthalic acid, 680 g of p-troyl acid and 0.191 g of tetraisopropyl titanate as an esterification catalyst are charged into a 2 L four-necked flask equipped with a thermometer, a stirrer and a slow cooling tube. The temperature is gradually raised with stirring until it reaches 230 ° C. in a nitrogen stream. The dehydration condensation reaction was carried out while observing the degree of polymerization. After completion of the reaction, unreacted 1,2-propylene glycol was distilled off under reduced pressure at 200 ° C. to obtain a polycondensed ester compound P2. The acid value was 0.30 and the number average molecular weight was 400.

(Preparation of silicon dioxide dispersion dilution)
Aerosil R812 (Nippon Aerosil Co., Ltd.) 10 parts by mass Ethanol 90 parts by mass The above was stirred and mixed with a dissolver for 30 minutes, and then dispersed with Manton Gorin. 88 parts by mass of methylene chloride was added to the silicon dioxide dispersion with stirring, and the mixture was stirred and mixed with a dissolver for 30 minutes to prepare a silicon dioxide dispersion dilution. It filtered with the fine particle dispersion | distribution dilution liquid filter (Advantech Toyo Co., Ltd .: Polypropylene wind cartridge filter TCW-PPS-1N).

(Preparation of dope 1)
TAC: Triacetyl cellulose (acetyl group substitution degree 2.89, Mw = 19000, Ca content 25 ppm) 100 parts by mass Tinuvin 928 (manufactured by BASF Japan Ltd.) 2.5 parts by mass Polycondensed ester compound P1 1.6 parts by mass Part Polycondensed ester compound P2 7.0 parts by weight Methylene chloride 540 parts by weight Ethanol 35 parts by weight The above was put into a sealed container, heated, stirred and completely dissolved, and filtered. To this, 4 parts by mass of the silicon dioxide dispersion dilution was added with stirring, and the mixture was further stirred for 30 minutes.

(Film formation / stretching / drying)
Next, using a belt casting apparatus, the cellulose acylate dope 1 was uniformly cast on a stainless steel band support at a temperature of 35 ° C. and a width of 2 m. With the stainless steel band support, the solvent was evaporated until the residual solvent amount reached 100% by mass, and the stainless steel band support was peeled off. The web of the peeled optical film is conveyed while being dried at 50 ° C., slitted, and then stretched by a tenter at a stretching ratio of 10% in a temperature direction of 160 ° C. in a TD direction (a direction perpendicular to the film conveying direction). did. At this time, the residual solvent amount when starting stretching with a tenter was 5.0%. Then, after being dried for 15 minutes while being transported in a drying apparatus at 120 ° C. by a number of rolls, slitting is performed, a knurling process of 15 mm in width and 10 μm in height is applied to both ends of the film, and a winding polarizing plate protective film is wound around the core. 1 was obtained. The residual solvent amount of the film was less than 0.1%, the film thickness was 24 μm, the width was 1.5 m, and the winding length was 3000 m.
In addition, the draw ratio of MD direction computed from the rotational speed of a stainless steel band support body and the driving speed of a tenter was 1.05 times.

(2) Preparation of polarizing plate protective film 2 (Preparation of dope 2)
A dope 2 having the following composition was prepared. First, methylene chloride and ethanol were added to the pressure dissolution tank. Cellulose ester A was added to a pressurized dissolution tank containing a solvent while stirring, and this was heated and completely dissolved while stirring.
Cellulose acetate (substitution degree 2.85, weight average molecular weight 280000)
100 parts by mass Acetyl saccharose (substitution degree 7.8) 7 parts by mass Polycondensation ester compound P1 4 parts by mass Matting agent: 12% ethanol dispersion of R812 (manufactured by Nippon Aerosil Co., Ltd.)
1.4 parts by mass Methylene chloride 430 parts by mass Ethanol 40 parts by mass

  Further, the additive component was put into a closed container and dissolved while stirring, and this was dissolved into Azumi filter paper No. 1 manufactured by Azumi Filter Paper Co., Ltd. Filtered using 244 to prepare Dope 2.

(Film formation)
The prepared dope 2 was uniformly cast on a stainless steel band support at a temperature of 22 ° C. and a width of 1.8 m using a belt casting apparatus. With the stainless steel band support, the solvent was evaporated until the residual solvent amount became 20%, and the film was peeled off from the stainless steel band support with a peeling tension of 162 N / m.

Next, the solvent of the peeled dope 2 was evaporated at 35 ° C., slit to 1.6 m width, and then, using a tenter stretching machine, when the glass transition temperature of the polarizing plate protective film was Tg, The film was stretched 1.05 times the original width in the width direction (TD direction) at a temperature of Tg + 20) ° C. At this time, the residual solvent amount when starting stretching with a tenter was 4%.
Then, drying was completed while transporting the drying zone of 120 ° C. and 140 ° C. with a large number of rollers, slitting to 1.3 m width, and knurling with a width of 10 mm and a height of 2.5 μm on both ends of the film, The film was wound around a core to prepare a polarizing plate protective film 2. The film thickness was 25 μm and the winding length was 5000 m.

(3) Bonding of polarizing plate protective film First, the following components were mixed and then defoamed to prepare an ultraviolet curable adhesive liquid 1. Triarylsulfonium hexafluorophosphate was blended as a 50% propylene carbonate solution, and the solid content of triarylsulfonium hexafluorophosphate was shown below.
3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate 45 parts by mass Epolide GT-301 (alicyclic epoxy resin manufactured by Daicel Chemical Industries) 40 parts by mass 1,4-butanediol diglycidyl ether 15 parts by mass Triarylsulfonium hexafluorophosphate 2.3 parts by mass 9,10-dibutoxyanthracene 0.1 parts by mass 1,4-diethoxynaphthalene 2.0 parts by mass

  The polarizing plate protective film 1 was used, and the surface was subjected to corona discharge treatment. The corona discharge treatment was performed at a corona output intensity of 2.0 kW and a line speed of 18 m / min. Next, the prepared ultraviolet curable adhesive liquid 1 is applied to the corona discharge-treated surface of the polarizing plate protective film 1 with a bar coater so that the layer thickness after curing is about 3 μm, and the ultraviolet curable adhesive is applied. A layer was formed. The polarizer side of the produced polarizing laminated films 1 to 25 was bonded to the obtained ultraviolet curable adhesive layer, and then the base film was peeled off.

  Subsequently, the produced polarizing plate protective film 2 was subjected to corona discharge treatment. The conditions of the corona discharge treatment were a corona output intensity of 2.0 kW and a speed of 18 m / min.

  Next, the prepared ultraviolet curable adhesive liquid 1 is applied to the corona discharge-treated surface of the polarizing plate protective film 2 with a bar coater so that the layer thickness after curing is about 3 μm, and the ultraviolet curable adhesive is applied. A layer was formed.

  A polarizer bonded to one surface of the polarizing plate protective film 1 is bonded to the ultraviolet curable adhesive layer, and the polarizing plate protective film 1 / UV curable adhesive layer / polarizer according to the present invention / UV light. A laminate in which the curable adhesive layer / polarizing plate protective film 2 was laminated was obtained.

From both sides of this laminate, using a UV irradiation device with a belt conveyor (the lamp uses a D bulb manufactured by Fusion UV Systems), UV light was applied so that the integrated light amount was 750 mJ / cm ^2. The ultraviolet curable adhesive layer was cured to produce polarizing plates 1-1 to 1-25.

<< Evaluation of Polarizing Plates 1-1 to 1-25 >>
The following evaluation was performed about the polarizing laminated films 1-25 produced as mentioned above. The evaluation results are shown in Table 2.

(Orientation unevenness)
Light was irradiated from below with the commercially available polarizing plates superimposed on the upper and lower sides of the polarizing plates 1-1 to 1-25, and alignment unevenness was confirmed visually from above. At that time, the two polarizing plates were arranged so that their absorption axes were parallel to each other. Moreover, it was arrange | positioned so that the extending | stretching direction of a laminated | multilayer film might make an angle of 45 degrees with respect to the absorption axis of a polarizing plate. Visual confirmation results were evaluated according to the following criteria. In addition, the lower the affinity between the base film and the hydrophilic polymer layer, the worse the coating property at the time of forming the hydrophilic polymer layer, and the more likely the orientation unevenness occurs.
◎: No orientation unevenness ○: Sparse orientation unevenness at the end △: Orientation unevenness at the end of the full length ×: Orientation unevenness over the entire surface

(4) Summary As shown in Tables 1 and 2, the production method of the present invention can suppress the occurrence of folding of the laminated film even when the base film has sufficient rigidity and the polyvinyl alcohol resin is crosslinked. It is clear that Furthermore, since the base film has high affinity with the polyvinyl alcohol resin, it was found that the polyvinyl alcohol layer can be uniformly applied and the effect of suppressing the alignment unevenness can be obtained.
Further, PET and PP used as the base film in the polarizing laminated films 26 and 27 of the comparative example have poor applicability of the hydrophilic polymer layer unless easy adhesion processing is performed. It can be seen that the coating property is sufficiently excellent even when the easy adhesion processing is not performed.

[Example 2]
<< Preparation of Polarizing Laminated Films 28-30 >>
In the production of the light-polarizing laminated film 14 in Example 1, except that the thickness of the base material film and the polarizer of the light-polarizing laminated film produced were changed to the values described in Table 3, respectively, Polarizing laminated films 28 to 30 were produced.

<< Evaluation of Polarizing Laminated Films 28-30 >>
As in Example 1, the polarizing laminate films 28 to 30 produced as described above were evaluated for coatability and folding during conveyance. The evaluation results are shown in Table 3. In addition, when the polarization degree of the polarizing laminated films 26 to 28 was measured using an ultraviolet-visible spectrophotometer (manufactured by JASCO Corporation, product name “V7100”), all were 99.95% or more.
Table 3 also shows the polarizing laminated film 14 in Example 1. In Table 3, PMMA represents polymethyl methacrylate.

<< Production of Polarizing Plates 2-1 to 2-3 >>
Subsequently, using the produced polarizing laminated films 28 to 30, polarizing plates 2-1 to 2-3 were produced in the same manner as the polarizing plates 1-1 to 1-25 in Example 1 described above. .

<< Production of Polarizing Plate 2-4 >>
The polarizing plate protective film 1 produced by the same method as in Example 1 on the surface of the base film on which the polarizer is not laminated, without peeling the base film from the produced polarizing laminated film 29. Was pasted. In this way, Polarizing Plate 2-4 was produced.

<< Evaluation of Polarizing Plates 2-1 to 2-4 >>
In the same manner as in Example 1, the polarization unevenness was evaluated for the polarizing laminated films 2-1 to 2-4 produced as described above. The evaluation results are shown in Table 4.
In Table 4, the polarizing laminated film 1-14 in Example 1 is also shown. Moreover, in Table 4, as a manufacturing method of a polarizing plate, the method of peeling a base film from a polarizing laminated film and sticking a polarizing plate protective film on both surfaces of the obtained polarizer is referred to as “Method 1”. The method of pasting the polarizing plate protective film on one side of the polarizer without peeling off the base film from the polarizing laminated film is shown as “Method 2”.

As shown in Tables 3 and 4, the polarizing laminate films having a base film thickness of 60.0 μm and 10.0 μm at the time of preparing the polarizing laminate film are polarized films having a base film thickness of 7.9 μm. It was found that the folding during transportation was better than that of the conductive laminated film, and that the folding was worsened when the thickness of the base film was too thin.
Furthermore, the polarizing laminate film having a base film thickness of 60.0 μm and 10.0 μm at the time of preparing the polarizing laminate film has a more uneven orientation than the polarizing laminate film having a thickness of 71.6 μm. It was found to be good, and if it was too thick, stretching unevenness was likely to occur.

[Example 3]
In the production of the polarizing laminated film of Example 1, each step was performed in the order of the lamination step, the stretching step, and the dyeing step. In this example, after the lamination step, the dyeing step was performed, Further, a polarizing laminated film 3A was produced as a step for performing a stretching step thereafter.
Moreover, the extending | stretching process shall wet-stretch a laminated | multilayer film in boric-acid aqueous solution. Specifically, the laminated film formed in the laminating step is mixed with an aqueous boric acid solution having a liquid temperature of 75 ° C. (4 parts by mass of boric acid and 5 parts by mass of potassium iodide are added to 100 parts by mass of water). While being immersed in the obtained aqueous solution), free end uniaxial stretching was performed in the longitudinal direction (longitudinal direction) between rolls having different peripheral speeds. The draw ratio at this time was 4 times.
In this example, the lamination process and the dyeing process were performed in the same manner as the production of the polarizing laminated film 1 in Example 1 above.

  When the applicability of the polarizing laminate film 3A thus obtained was evaluated in the same manner as in Example 1, the applicability was superior to that of the polarizing laminate films 1-27 of Example 1. It was.

  Moreover, in preparation of polarizing laminated film 3A, the air extending | stretching process shall be performed further and polarizing laminated film 3B was produced. Specifically, after performing the laminating process and before performing the dyeing process and the stretching process, the laminated film is placed in the longitudinal direction (longitudinal direction) between rolls having different peripheral speeds in an oven at 130 ° C. The free end was uniaxially stretched 8 times. When the applicability of the polarizing laminate film 3B thus obtained was evaluated in the same manner as in Example 1, it showed a coating property further superior to that of the polarizing laminate film 3A.

  Further, polarizing plates 3-1 and 3-2 were produced using the produced polarizing laminated films 3 </ b> A and 3 </ b> B in the same manner as the production method of the polarizing plate 1-1 of Example 1 above. About the produced polarizing plate 3-1, 3-2, when the orientation nonuniformity was evaluated by the method similar to the said Example 1, the orientation nonuniformity further reduced rather than the polarizing plate 1-1 to 1-25 of Example 1. FIG. .

[Example 4]
As an IPS mode liquid crystal display device having a display area with a diagonal length of 4 inches, i-phone 5s made by Apple was prepared, and then two polarizing plates were peeled off. Next, two polarizing plates with the same number among the polarizing plates 1-1 to 1-25 according to the present invention prepared above were prepared and bonded to both surfaces of the liquid crystal cell to obtain a display device. The lamination was arranged so that the polarizing plate protective film 2 was in contact with the liquid crystal cell. It was made for the absorption axis of a polarizing plate and the absorption axis of the polarizing plate previously stuck to become the same direction.
The display device manufactured using the polarizing plate of the present invention had good visibility.

Claims (13)

A method for producing a polarizing laminated film comprising at least a base film and a polarizer laminated,
A hydrophilic high polymer containing a hydrophilic polymer by sequential coating or coextrusion on the base film containing at least two kinds of resins including at least a carboxylic acid vinyl ester resin and having at least two glass transition points. A step of laminating molecular layers to form a laminated film;
Stretching the laminated film;
Dyeing the hydrophilic polymer layer with a dichroic substance;
A method for producing a polarizing laminated film, comprising:   In the process of extending | stretching the said laminated | multilayer film, the extending | stretching temperature of the said laminated | multilayer film is a temperature between the at least 2 glass transition points of the said base film, The polarizing laminated film of Claim 1 characterized by the above-mentioned. Production method.   The manufacturing method of the polarizing laminated film according to claim 1 or 2, wherein the highest glass transition point among at least two glass transition points of the base film is 70 ° C or more.   The temperature difference between the highest glass transition point and the lowest glass transition point among at least two glass transition points of the base film is 30 ° C or more. The manufacturing method of the light-polarizing laminated film as described in any one of these.   The said base film contains at least 1 sort (s) of resin in the range of the weight average molecular weights 100,000-1 million, The polarizing laminated film as described in any one of Claim 1- Claim 4 characterized by the above-mentioned. Production method.   The mass composition ratio of the carboxylic acid vinyl ester resin (resin A) contained in the base film is (rA), and the resin other than the carboxylic acid vinyl ester resin among the two or more kinds of resins contained in the base film And when the mass composition ratio of the resin having the highest glass transition point (resin B) is (rB), it is in the range of (rA) :( rB) = 9: 1 to 1: 9. The manufacturing method of the light-polarizing laminated film as described in any one of Claim 1- Claim 5.   The thickness of the base film after the step of stretching the laminated film and the step of dyeing the hydrophilic polymer layer is in the range of 10 to 60 µm. The manufacturing method of the light-polarizing laminated film as described in any one of the above.   In the step of forming the laminated film, the base is obtained by casting a dope containing at least two kinds of resins including a carboxylic acid vinyl ester resin and a solvent on a metal support, separating the dope, and drying the dope. A polarizing film according to any one of claims 1 to 7, wherein a material film is formed, and the hydrophilic polymer is laminated on the formed base film by a solution casting method. A method for producing a laminated film. In the step of stretching the laminated film, the laminated film is uniaxially stretched at a stretch ratio of 4 times or more,
The process of forming the said laminated | multilayer film, the process of extending | stretching the said laminated | multilayer film, and the process of dye | staining the said hydrophilic polymer layer are performed in this order in any one of Claim 1-8 characterized by the above-mentioned. The manufacturing method of the polarizing laminated film of description. In the step of stretching the laminated film, the laminated film is wet-stretched in an aqueous boric acid solution,
The process of forming the said laminated | multilayer film, the process of dyeing | staining the said hydrophilic polymer layer, and the process of extending | stretching the said base film are performed in this order. The manufacturing method of the polarizing laminated film of description.   The method for producing a polarizing laminated film according to claim 10, wherein a step of stretching the laminated film in the air is performed before the step of dyeing the hydrophilic polymer layer.   At least one surface of the polarizer of the polarizing laminated film following the step of producing a polarizing laminated film by the method for producing a polarizing laminated film according to any one of claims 1 to 11. The manufacturing method of the polarizing plate characterized by having the process of sticking a polarizing plate protective film on the surface.   In the step of bonding the polarizing plate protective film, after peeling the base film from the polarizing laminated film, the polarizing plate protective film is bonded to the surface of the polarizer that is in contact with the base film. The manufacturing method of the polarizing plate of Claim 12 characterized by the above-mentioned.

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