JP4801419B2 - Polarizer - Google Patents

Description

  The present invention relates to a polarizing plate formed by bonding a protective film to a polarizer with an adhesive.

  Conventionally, liquid crystal display devices (hereinafter sometimes referred to as “LCDs”) have been widely used mainly for electronic devices used indoors, such as personal computers and televisions. Recently, however, such as car navigation systems and portable information terminals. It has also been increasingly used for electronic devices used outdoors. Therefore, LCDs are strongly required to have high display characteristics and reliability in a severe atmosphere such as high temperature and high humidity.

  In general, a polarizing plate is indispensable for LCDs as a component, and the polarizing plate is bonded to both or one side of a liquid crystal cell in which liquid crystal is sealed between two electrode substrates forming a transparent electrode. Used. The polarizing plate has a laminated structure in which a protective film is bonded to both surfaces of a polarizer having a polarizing function with an adhesive. As a material of the polarizer, polyvinyl alcohol (hereinafter sometimes referred to as “PVA”) is mainly used. For example, the PVA film is uniaxially stretched and then dyed with iodine or a dichroic dye, or dyed. Then, the polarizer is produced by stretching and then crosslinking with a boron compound.

  By the way, PVA film has weak mechanical strength with respect to the transmission axis direction, and may shrink due to heat or moisture, or the polarization function may be lowered. Therefore, protective films are usually bonded to both sides of PVA film. Has been. In general, protective films have no birefringence, high light transmittance, good heat resistance and moisture resistance, high mechanical strength, small shrinkage due to changes in temperature and humidity, smooth surface, resolution Therefore, various performances such as high compatibility with the adhesive and excellent appearance are required. At present, as a protective film satisfying such requirements, a solution cast film of triacetyl cellulose (hereinafter sometimes referred to as “TAC”) is mainly used because of its low birefringence and good appearance. Is used. Usually, a protective film made of TAC is bonded to both surfaces of a polarizer made of PVA with a water-soluble adhesive.

  However, the TAC film has insufficient moisture resistance, and in a high-temperature and high-humidity environment, for example, in an atmosphere of 80 ° C. and 90 RH%, the polarizer made of PVA deteriorates in about 100 hours, and the polarizing function is lowered. End up. Further, the TAC film has insufficient gas barrier properties, and there is a problem that iodine or dichroic dye is easily altered by permeated oxygen. Moreover, since a plasticizer is added to the TAC film in order to impart film forming properties, there is also a problem that the heat resistance is not sufficient. Furthermore, since a TAC film having a thickness of 40 μm or less has low strength and durability, for example, it is necessary to use a TAC film having a thickness of 80 μm, which is one factor that hinders the thinning of the polarizing plate.

  In order to solve the above problem, for example, Patent Document 1 proposes to use a resin film having a moisture permeability lower than that of the TAC film, for example, an amorphous polyolefin resin as a protective film. Specifically, a thermoplastic saturated norbornene resin film is bonded as a protective film to at least one surface of the PVA sheet. When pasting such a protective film with low moisture permeability with a conventional apparatus, an adhesive having water as a main solvent, for example, an aqueous polyvinyl alcohol solution was used, and the protective film was pasted on a PVA polarizer. Thereafter, in the so-called wet lamination in which the solvent is dried, there is a problem that sufficient adhesive strength cannot be obtained or the appearance becomes poor. This is because a film having a low moisture permeability is generally more hydrophobic than a TAC film, and because the moisture permeability is low, water as a solvent cannot be sufficiently dried.

  Patent Document 2 proposes that a PVA polarizer and a protective film made of a thermoplastic norbornene resin are bonded with a polyurethane adhesive. However, the adhesive strength was not always sufficient.

  Furthermore, (meth) acrylic resins such as polymethyl methacrylate (hereinafter sometimes referred to as “PMMA”) are known as resin materials having excellent optical transparency. For example, Patent Document 3 discloses a polarizing plate. The use as a protective film is reported. However, when (meth) acrylic resin is used as a protective film, in order to improve the adhesion with the polarizer, for example, an easy adhesion treatment such as corona discharge is performed on the surface of the protective film facing the polarizer. In the vicinity of the surface of the protective film after bonding facing the polarizer, cohesive failure may occur, and the adhesiveness with the polarizer may not be sufficiently exhibited.

On the other hand, as a thermoplastic resin having both heat resistance and optical transparency, a lactone ring-containing polymer obtained by lactone cyclization condensation of a polymer having a hydroxyl group and an ester group in a molecular chain is known. (For example, refer to Patent Documents 4, 5, and 6).
JP 2003-211589 A JP 2000-32432 A JP 2000-356714 A JP 2000-230016 A JP 2001-151814 A JP-A-2005-146084

  Under the circumstances described above, the problem to be solved by the present invention is that a polarizing plate formed by bonding a protective film to a polarizer with an adhesive has high adhesive strength between the polarizer and the protective film, and excellent bending resistance. Another object of the present invention is to provide a polarizing plate having reworkability, water resistance, moisture resistance and the like.

As a result of various studies, the present inventors have used a thermoplastic resin film containing a lactone ring-containing polymer as a main component as a protective film, and on the surface of the protective film facing the polarizer, polyurethane resin and / or amino If an easy-adhesion layer containing a group-containing polymer is formed, even if the protective film is bonded to the polarizer with a normal adhesive, adhesion between the polarizer and the protective film in addition to excellent optical properties The present invention was completed by finding that a polarizing plate having high strength and excellent bending resistance, reworkability, water resistance, moisture resistance and the like can be obtained.

  That is, the present invention is a polarizing plate in which a thermoplastic resin film mainly composed of a lactone ring-containing polymer is bonded to at least one surface of a polarizer with an adhesive, and the polarizing plate of the thermoplastic resin film Provided is a polarizing plate characterized in that an easy-adhesion layer containing a polyurethane resin and / or an amino group-containing polymer is formed on a surface facing a child.

  The lactone ring-containing polymer is preferably the following formula (1):

[Wherein R ¹ , R ² and R ³ independently represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms; the organic residue may contain an oxygen atom]
Having a lactone ring structure.

  The adhesive is preferably a polyurethane adhesive and / or an isocyanate adhesive.

  The polarizing plate of the present invention has high adhesive strength between the polarizer and the protective film in addition to excellent optical properties, and has excellent bending resistance, rework property, water resistance, moisture resistance, etc. Even if it is left in a harsh environment for a long time, the polarizer and the protective film are difficult to peel off. Therefore, the problem of the conventional polarizing plate using the TAC film as a protective film can be solved.

  Hereinafter, the polarizing plate of the present invention will be described in detail. However, the scope of the present invention is not limited by these descriptions, and other than the following examples, the scope of the present invention can be changed as appropriate without departing from the spirit of the present invention. Can be implemented.

≪Polarizing plate≫
The polarizing plate of the present invention is a polarizing plate in which a thermoplastic resin film mainly composed of a lactone ring-containing polymer is bonded to at least one surface of a polarizer with an adhesive, and the polarizing plate of the thermoplastic resin film An easy-adhesion layer containing a polyurethane resin and / or an amino group-containing polymer is formed on the surface facing the polarizer. That is, in the polarizing plate of the present invention, a predetermined thermoplastic resin film is bonded to one surface of the polarizer with an adhesive via a predetermined easy adhesion layer, but the other surface of the polarizer is Similarly, a predetermined thermoplastic resin film is bonded with an adhesive via a predetermined easy-adhesion layer, or a conventionally known protective film, for example, a TAC subjected to a known easy-adhesion process such as a saponification process The film is bonded with a known adhesive. The phrase “consisting of a lactone ring-containing polymer as a main component” means that at least 50% by mass or more of the resin constituting the thermoplastic resin film is a lactone ring-containing polymer.

≪Protective film≫
In the polarizing plate of the present invention, the polarizer is mainly composed of a lactone ring-containing polymer as a protective film via an easy adhesion layer containing a polyurethane resin and / or an amino group-containing polymer on at least one surface thereof. A thermoplastic resin film is bonded. The lactone ring-containing polymer that is the main component of the thermoplastic resin film is preferably the following formula (1):

[Wherein R ¹ , R ² and R ³ independently represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms; the organic residue may contain an oxygen atom]
Having a lactone ring structure.

  The content of the lactone ring structure represented by the above formula (1) in the structure of the lactone ring-containing polymer is preferably 5 to 90% by mass, more preferably 10 to 70% by mass, and still more preferably 10 to 60% by mass. Especially preferably, it is 10-50 mass%. When the content of the lactone ring structure is less than 5% by mass, the heat resistance, solvent resistance, and surface hardness of the obtained polymer may be lowered. On the contrary, when the content of the lactone ring structure exceeds 90% by mass, the moldability of the obtained polymer may be deteriorated.

  The lactone ring-containing polymer may have a structure other than the lactone ring structure represented by the above formula (1). The structure other than the lactone ring structure represented by the above formula (1) is not particularly limited. For example, a (meth) acrylic acid ester, which will be described later as a method for producing a lactone ring-containing polymer, Hydroxyl group-containing monomer, unsaturated carboxylic acid, and the following formula (2):

[Wherein, R ⁴ represents a hydrogen atom or a methyl group, and X represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group, an —OAc group, a —CN group, a —CO—R ⁵ group, or —CO —O—R ⁶ group, Ac represents an acetyl group, R ⁵ and R ⁶ represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms]
A polymer structural unit (repeating structural unit) formed by polymerizing at least one monomer selected from the group consisting of monomers represented by formula (1) is preferred.

  The content ratio of the structure other than the lactone ring structure represented by the above formula (1) in the structure of the lactone ring-containing polymer is a polymer structural unit (repeated structural unit) formed by polymerizing (meth) acrylic acid ester. In this case, it is preferably 10 to 95% by mass, more preferably 10 to 90% by mass, further preferably 40 to 90% by mass, and particularly preferably 50 to 90% by mass, and is formed by polymerizing a hydroxyl group-containing monomer. In the case of a polymer structural unit (repeating structural unit), preferably 0 to 30% by mass, more preferably 0 to 20% by mass, still more preferably 0 to 15% by mass, particularly preferably 0 to 10% by mass. . In the case of a polymer structural unit (repeating structural unit) formed by polymerizing an unsaturated carboxylic acid, it is preferably 0 to 30% by mass, more preferably 0 to 20% by mass, and still more preferably 0 to 15% by mass. Especially preferably, it is 0-10 mass%. Furthermore, in the case of a polymer structural unit (repeating structural unit) formed by polymerizing the monomer represented by the above formula (2), preferably 0 to 30% by mass, more preferably 0 to 20% by mass, Preferably it is 0-15 mass%, Most preferably, it is 0-10 mass%.

  The method for producing the lactone ring-containing polymer is not particularly limited. For example, the polymer obtained after obtaining the polymer (a) having a hydroxyl group and an ester group in the molecular chain by a polymerization step. It is obtained by carrying out a lactone cyclization condensation step for introducing a lactone ring structure into the polymer by heat-treating (a).

  In the polymerization step, for example, the following formula (3):

[Wherein, R ⁵ and R ⁶ each independently represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms]
The polymer which has a hydroxyl group and an ester group in a molecular chain is obtained by performing the polymerization reaction of the monomer component which mix | blended the monomer shown by.

  Examples of the monomer represented by the above formula (3) include methyl 2- (hydroxymethyl) acrylate, ethyl 2- (hydroxymethyl) acrylate, isopropyl 2- (hydroxymethyl) acrylate, and 2- (hydroxy Examples include methyl) n-butyl acrylate, t-butyl 2- (hydroxymethyl) acrylate, and the like. These monomers may be used alone or in combination of two or more. Among these monomers, 2- (hydroxymethyl) methyl acrylate and 2- (hydroxymethyl) ethyl acrylate are preferable, and since the effect of improving heat resistance is high, methyl 2- (hydroxymethyl) acrylate Is particularly preferred.

  The content ratio of the monomer represented by the formula (3) in the monomer component to be subjected to the polymerization step is preferably 5 to 90% by mass, more preferably 10 to 70% by mass, and still more preferably 10 to 60% by mass. %, Particularly preferably 10 to 50% by mass. When the content ratio of the monomer represented by the above formula (3) is less than 5% by mass, the heat resistance, solvent resistance and surface hardness of the obtained polymer may be lowered. On the contrary, when the content ratio of the monomer represented by the above formula (3) exceeds 90% by mass, gelation may occur in the polymerization step or the lactone cyclization condensation step, and the moldability of the obtained polymer may be increased. May decrease.

  You may mix | blend monomers other than the monomer shown by the said Formula (3) with the monomer component with which it uses for a superposition | polymerization process. Such a monomer is not particularly limited. For example, (meth) acrylic acid ester, hydroxyl group-containing monomer, unsaturated carboxylic acid, and the following formula (2):

[Wherein, R ⁴ represents a hydrogen atom or a methyl group, and X represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group, an —OAc group, a —CN group, a —CO—R ⁵ group, or —CO —O—R ⁶ group, Ac represents an acetyl group, R ⁵ and R ⁶ represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms]
And the like. These monomers may be used alone or in combination of two or more.

  The (meth) acrylic acid ester is not particularly limited as long as it is a (meth) acrylic acid ester other than the monomer represented by the above formula (3). For example, methyl acrylate, ethyl acrylate Acrylates such as n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, cyclohexyl acrylate, and benzyl acrylate; methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, methacrylic acid And methacrylic acid esters such as isobutyl, t-butyl methacrylate, cyclohexyl methacrylate, and benzyl methacrylate. These (meth) acrylic acid esters may be used alone or in combination of two or more. Among these (meth) acrylic acid esters, methyl methacrylate is particularly preferable because the obtained polymer has excellent heat resistance and transparency.

  When using a (meth) acrylic acid ester other than the monomer represented by the above formula (3), the content ratio in the monomer component to be subjected to the polymerization step is sufficient to exert the effect of the present invention. Preferably it is 10-95 mass%, More preferably, it is 10-90 mass%, More preferably, it is 40-90 mass%, Most preferably, it is 50-90 mass%.

  The hydroxyl group-containing monomer is not particularly limited as long as it is a hydroxyl group-containing monomer other than the monomer represented by the above formula (3). For example, α-hydroxymethylstyrene, α-hydroxy And 2- (hydroxyalkyl) acrylic acid esters such as ethyl styrene and methyl 2- (hydroxyethyl) acrylate; 2- (hydroxyalkyl) acrylic acids such as 2- (hydroxyethyl) acrylic acid; and the like. These hydroxyl group-containing monomers may be used alone or in combination of two or more.

  When a hydroxyl group-containing monomer other than the monomer represented by the above formula (3) is used, the content ratio in the monomer component to be subjected to the polymerization step is preferable in order to sufficiently exhibit the effects of the present invention. Is 0 to 30% by mass, more preferably 0 to 20% by mass, still more preferably 0 to 15% by mass, and particularly preferably 0 to 10% by mass.

  Examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, crotonic acid, α-substituted acrylic acid, α-substituted methacrylic acid and the like. These unsaturated carboxylic acids may be used alone or in combination of two or more. Among these unsaturated carboxylic acids, acrylic acid and methacrylic acid are particularly preferable because the effects of the present invention are sufficiently exhibited.

  When using an unsaturated carboxylic acid, the content ratio in the monomer component to be subjected to the polymerization step is preferably 0 to 30% by mass, more preferably 0 to 20% by mass, in order to sufficiently exhibit the effects of the present invention. %, More preferably 0 to 15% by mass, particularly preferably 0 to 10% by mass.

  Examples of the monomer represented by the formula (2) include styrene, α-methylstyrene, vinyl toluene, acrylonitrile, methyl vinyl ketone, ethylene, propylene, and vinyl acetate. These monomers may be used alone or in combination of two or more. Of these monomers, styrene and α-methylstyrene are particularly preferable because the effects of the present invention are sufficiently exhibited.

  When the monomer represented by the above formula (2) is used, the content ratio in the monomer component to be subjected to the polymerization step is preferably 0 to 30% by mass in order to sufficiently exhibit the effects of the present invention. More preferably, it is 0-20 mass%, More preferably, it is 0-15 mass%, Most preferably, it is 0-10 mass%.

  The form of the polymerization reaction for polymerizing the monomer components to obtain a polymer having a hydroxyl group and an ester group in the molecular chain is preferably a polymerization form using a solvent, and solution polymerization is particularly preferred.

  The polymerization temperature and the polymerization time vary depending on the type and ratio of the monomer used. For example, the polymerization temperature is preferably 0 to 150 ° C., the polymerization time is 0.5 to 20 hours, and more Preferably, the polymerization temperature is 80 to 140 ° C. and the polymerization time is 1 to 10 hours.

  In the case of a polymerization form using a solvent, the polymerization solvent is not particularly limited. For example, aromatic hydrocarbon solvents such as toluene, xylene, and ethylbenzene; ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone; tetrahydrofuran And ether solvents such as These solvents may be used alone or in combination of two or more. Moreover, since the residual volatile matter of the lactone ring containing polymer finally obtained will increase when the boiling point of a solvent is too high, the solvent whose boiling point is 50-200 degreeC is preferable.

  During the polymerization reaction, a polymerization initiator may be added as necessary. The polymerization initiator is not particularly limited. For example, cumene hydroperoxide, diisopropylbenzene hydroperoxide, di-t-butyl peroxide, lauroyl peroxide, benzoyl peroxide, t-butylperoxyisopropyl Organic peroxides such as carbonate and t-amylperoxy-2-ethylhexanoate; 2,2′-azobis (isobutyronitrile), 1,1′-azobis (cyclohexanecarbonitrile), 2,2 ′ -Azo compounds such as azobis (2,4-dimethylvaleronitrile); These polymerization initiators may be used alone or in combination of two or more. The amount of the polymerization initiator used is not particularly limited as long as it is appropriately set according to the combination of monomers and reaction conditions.

  When performing the polymerization, it is preferable to control the concentration of the polymer produced in the polymerization reaction mixture to be 50% by mass or less in order to suppress gelation of the reaction solution. Specifically, when the concentration of the polymer formed in the polymerization reaction mixture exceeds 50% by mass, it is preferable that the polymerization solvent is appropriately added to the polymerization reaction mixture and controlled to be 50% by mass or less. . The concentration of the polymer formed in the polymerization reaction mixture is more preferably 45% by mass or less, and further preferably 40% by mass or less. In addition, since productivity will fall when the density | concentration of the polymer produced | generated in the polymerization reaction mixture is too low, the density | concentration of the polymer produced | generated in the polymerization reaction mixture becomes like this. Preferably it is 10 mass% or more, More preferably, it is 20 mass%. That's it.

  The form in which the polymerization solvent is appropriately added to the polymerization reaction mixture is not particularly limited, and for example, the polymerization solvent may be added continuously or the polymerization solvent may be added intermittently. By controlling the concentration of the polymer formed in the polymerization reaction mixture in this way, the gelation of the reaction solution can be more sufficiently suppressed, and in particular, to increase the lactone ring content and improve the heat resistance. Even when the ratio between the hydroxyl group and the ester group in the molecular chain is increased, gelation can be sufficiently suppressed. The polymerization solvent to be added may be, for example, the same type of solvent used during the initial charging of the polymerization reaction or a different type of solvent, but the solvent used during the initial charging of the polymerization reaction. It is preferable to use the same type of solvent. Moreover, the polymerization solvent to be added may be only one kind of single solvent or two or more kinds of mixed solvents.

  The polymerization reaction mixture obtained when the above polymerization step is completed usually contains a solvent in addition to the obtained polymer, but it is necessary to completely remove the solvent and take out the polymer in a solid state. Rather, it is preferably introduced into the subsequent lactone cyclization condensation step in a state containing a solvent. If necessary, after taking out in a solid state, a solvent suitable for the subsequent lactone cyclization condensation step may be added again.

  The polymer obtained in the polymerization step is a polymer (a) having a hydroxyl group and an ester group in the molecular chain, and the weight average molecular weight of the polymer (a) is preferably 1,000 to 2,000,000. 000, more preferably 5,000 to 1,000,000, still more preferably 10,000 to 500,000, particularly preferably 50,000 to 500,000. In addition, a weight average molecular weight is the value calculated | required by polystyrene conversion using gel permeation chromatography. The polymer (a) obtained in the polymerization step is subjected to heat treatment in the subsequent lactone cyclization condensation step, whereby a lactone ring structure is introduced into the polymer to become a lactone ring-containing polymer.

  The reaction for introducing a lactone ring structure into the polymer (a) is a reaction in which a hydroxyl group and an ester group present in the molecular chain of the polymer (a) are cyclized and condensed to form a lactone ring structure by heating. Yes, by the cyclocondensation, alcohol is by-produced. By forming the lactone ring structure in the molecular chain of the polymer (in the main skeleton of the polymer), high heat resistance is imparted. If the reaction rate of the cyclization condensation reaction leading to the lactone ring structure is insufficient, the heat resistance will not be improved sufficiently, or a condensation reaction will occur during the molding due to the heat treatment during molding, and the resulting alcohol will be contained in the molded product. May exist as bubbles or silver streaks.

  The lactone ring-containing polymer obtained in the lactone cyclization condensation step is preferably the following formula (1):

[Wherein R ¹ , R ² and R ³ independently represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms; the organic residue may contain an oxygen atom]
Having a lactone ring structure.

  The method for heat-treating the polymer (a) is not particularly limited, and a conventionally known method may be used. For example, you may heat-process the polymerization reaction mixture containing the solvent obtained by the superposition | polymerization process as it is. Or you may heat-process using a ring-closure catalyst as needed in presence of a solvent. Or heat processing can also be performed using the heating furnace and reaction apparatus provided with the vacuum apparatus or devolatilization apparatus for removing a volatile component, the extruder provided with the devolatilization apparatus, etc.

  In carrying out the cyclization condensation reaction, in addition to the polymer (a), another thermoplastic resin may coexist. When performing the cyclization condensation reaction, if necessary, an esterification catalyst or a transesterification catalyst such as p-toluenesulfonic acid generally used as a catalyst for the cyclization condensation reaction may be used. Organic carboxylic acids such as propionic acid, benzoic acid, acrylic acid, and methacrylic acid may be used as a catalyst. Furthermore, as disclosed in, for example, Japanese Patent Application Laid-Open Nos. 61-254608 and 61-261303, basic compounds, organic carboxylates, carbonates, and the like may be used.

  Alternatively, an organophosphorus compound may be used as a catalyst for the cyclization condensation reaction. Examples of the organic phosphoric acid compounds that can be used include alkyl (aryl) phosphonous acids such as methyl phosphonous acid, ethyl phosphonous acid, and phenyl phosphonous acid (however, these are alkyl (aryl) which are tautomers. ) Which may be phosphinic acid) and their monoesters or diesters; dialkyl (aryl) phosphinic acids such as dimethylphosphinic acid, diethylphosphinic acid, diphenylphosphinic acid, phenylmethylphosphinic acid, phenylethylphosphinic acid and their Esters; alkyl (aryl) phosphonic acids such as methylphosphonic acid, ethylphosphonic acid, trifluoromethylphosphonic acid, phenylphosphonic acid and their monoesters or diesters; methylphosphinic acid, ethylphosphinic acid Alkyl (aryl) phosphinic acids such as phenylphosphinic acid and esters thereof; methyl phosphite, ethyl phosphite, phenyl phosphite, dimethyl phosphite, diethyl phosphite, diphenyl phosphite, phosphorus phosphite Phosphorous acid monoester, diester or triester such as trimethyl phosphate, triethyl phosphite, triphenyl phosphite; methyl phosphate, ethyl phosphate, 2-ethylhexyl phosphate, octyl phosphate, isodecyl phosphate, phosphoric acid Lauryl, stearyl phosphate, isostearyl phosphate, phenyl phosphate, dimethyl phosphate, diethyl phosphate, di-2-ethylhexyl phosphate, diisodecyl phosphate, dilauryl phosphate, distearyl phosphate, diisostearyl phosphate, Diphenyl phosphate, trimethyl phosphate, triethyl phosphate Phosphoric acid monoesters, diesters or triesters such as triisodecyl phosphate, trilauryl phosphate, tristearyl phosphate, triisostearyl phosphate, triphenyl phosphate; methylphosphine, ethylphosphine, phenylphosphine, dimethylphosphine, diethylphosphine , Diphenylphosphine, trimethylphosphine, triethylphosphine, triphenylphosphine, etc. mono-, di- or tri-alkyl (aryl) phosphine; methyldichlorophosphine, ethyldichlorophosphine, phenyldichlorophosphine, dimethylchlorophosphine, diethylchlorophosphine, diphenyl Alkyl (aryl) halogen phosphines such as chlorophosphine; methylphosphine oxide, ethylphosphine oxide, oxide Mono-, di- or tri-alkyl (aryl) phosphines such as phenyl phosphine, dimethyl phosphine oxide, diethyl phosphine oxide, diphenyl phosphine oxide, trimethyl phosphine oxide, triethyl phosphine oxide, triphenyl phosphine oxide; tetramethylphosphonium chloride, chloride And halogenated tetraalkyl (aryl) phosphoniums such as tetraethylphosphonium and tetraphenylphosphonium chloride. These organic phosphorus compounds may be used alone or in combination of two or more. Among these organophosphorus compounds, since the catalytic activity is high and the colorability is low, alkyl (aryl) phosphonous acid, phosphorous acid monoester or diester, phosphoric acid monoester or diester, and alkyl (aryl) phosphonic acid Preferably, alkyl (aryl) phosphonous acid, phosphorous acid monoester or diester, phosphoric acid monoester or diester is more preferable, and alkyl (aryl) phosphonous acid, phosphoric acid monoester or diester is particularly preferable.

  Although the usage-amount of the catalyst used in the case of a cyclization condensation reaction is not specifically limited, For example, Preferably it is 0.001-5 mass% with respect to a polymer (a), More preferably, it is 0.00. It is 01-2.5 mass%, More preferably, it is 0.01-1 mass%, Most preferably, it is 0.05-0.5 mass%. When the amount of the catalyst used is less than 0.001% by mass, the reaction rate of the cyclization condensation reaction may not be sufficiently improved. On the other hand, when the amount of the catalyst used exceeds 5% by mass, the obtained polymer may be colored or the polymer may be cross-linked to make melt molding difficult.

  The addition timing of the catalyst is not particularly limited. For example, the catalyst may be added at the beginning of the reaction, may be added during the reaction, or may be added in both of them.

  It is preferable to carry out the cyclization condensation reaction in the presence of a solvent and to use a devolatilization step in combination with the cyclization condensation reaction. In this case, a mode in which the devolatilization step is used throughout the cyclization condensation reaction and a mode in which the devolatilization step is not used over the entire cyclization condensation reaction but only in a part of the process. In the method using the devolatilization step in combination, the alcohol produced as a by-product in the condensation cyclization reaction is forcibly devolatilized and removed, so that the equilibrium of the reaction is advantageous for the production side.

  The devolatilization process means a process of removing volatile components such as solvents and residual monomers and alcohol by-produced by a cyclization condensation reaction leading to a lactone ring structure under reduced pressure heating conditions as necessary. To do. If this removal treatment is insufficient, residual volatile components in the obtained polymer increase, and coloring may occur due to deterioration during molding, and molding defects such as bubbles and silver streaks may occur.

  In the case of using a devolatilization step throughout the cyclization condensation reaction, the apparatus to be used is not particularly limited. For example, in order to more effectively perform the present invention, a devolatilization step and devolatilization are performed. It is preferable to use a devolatilizer comprising a tank and an extruder with a vent, or a devolatilizer and an extruder arranged in series, and a devolatilizer comprising a heat exchanger and a devolatilizer or an extrusion with a vent It is more preferable to use a machine.

  The reaction treatment temperature in the case of using a devolatilizer comprising a heat exchanger and a devolatilizer is preferably 150 to 350 ° C, more preferably 200 to 300 ° C. If the reaction treatment temperature is less than 150 ° C., the cyclization condensation reaction may be insufficient and the residual volatile matter may increase. Conversely, when the reaction treatment temperature exceeds 350 ° C., the obtained polymer may be colored or decomposed.

  The reaction treatment pressure when using a devolatilizer comprising a heat exchanger and a devolatilizer is preferably 931 to 1.33 hPa (700 to 1 mmHg), more preferably 798 to 66.5 hPa (600 to 50 mmHg). . When the reaction treatment pressure exceeds 931 hPa (700 mmHg), volatile components including alcohol may easily remain. Conversely, if the reaction treatment pressure is less than 1.33 hPa (1 mmHg), industrial implementation may be difficult.

  When using an extruder with a vent, one or a plurality of vents may be used, but it is preferable to have a plurality of vents.

  The reaction treatment temperature when using an extruder with a vent is preferably 150 to 350 ° C, more preferably 200 to 300 ° C. If the reaction treatment temperature is less than 150 ° C., the cyclization condensation reaction may be insufficient and the residual volatile matter may increase. Conversely, when the reaction treatment temperature exceeds 350 ° C., the obtained polymer may be colored or decomposed.

  The reaction processing pressure when using an extruder with a vent is preferably 931 to 1.33 hPa (700 to 1 mmHg), more preferably 798 to 13.3 hPa (600 to 10 mmHg). When the reaction treatment pressure exceeds 931 hPa (700 mmHg), volatile components including alcohol may easily remain. Conversely, if the reaction treatment pressure is less than 1.33 hPa (1 mmHg), industrial implementation may be difficult.

  In the case of a form in which a devolatilization step is used throughout the cyclization condensation reaction, the physical properties of the lactone ring-containing polymer obtained may deteriorate under severe heat treatment conditions, as will be described later. It is preferable to carry out by using an extruder with a vent etc. on the conditions as mild as possible.

  In the case where the devolatilization step is used in combination throughout the cyclization condensation reaction, the polymer (a) obtained in the polymerization step is preferably introduced into the cyclization condensation reaction device together with a solvent. Depending on the situation, it may be passed once again through a cyclocondensation reaction apparatus such as a vented extruder.

  You may perform the form used together only in a part of process, without using a devolatilization process over the whole process of cyclization condensation reaction. For example, the apparatus for producing the polymer (a) is further heated, and if necessary, a part of the devolatilization step is used together to advance the cyclization condensation reaction to some extent in advance, followed by the devolatilization step. Is a form in which a cyclization condensation reaction is simultaneously used to complete the reaction.

  In the form of using the devolatilization step throughout the cyclization condensation reaction described above, for example, when the polymer (a) is heat-treated at a high temperature of about 250 ° C. or higher using a twin-screw extruder. Depending on the thermal history, partial decomposition or the like may occur before the cyclization condensation reaction occurs, and the physical properties of the resulting lactone ring-containing polymer may deteriorate. Therefore, if the cyclization condensation reaction is allowed to proceed to some extent before the cyclization condensation reaction using the devolatilization process at the same time, the latter reaction conditions can be relaxed, and the physical properties of the resulting lactone ring-containing polymer deteriorated. Is preferable. As a particularly preferred form, for example, a form in which the devolatilization step is started after a lapse of time from the start of the cyclization condensation reaction, that is, a hydroxyl group and an ester present in the molecular chain of the polymer (a) obtained in the polymerization step A mode in which a group is preliminarily subjected to a cyclization condensation reaction to increase the cyclization condensation reaction rate to some extent and then a cyclization condensation reaction using a devolatilization step simultaneously is performed. Specifically, for example, a cyclization condensation reaction is allowed to proceed to a certain reaction rate in the presence of a solvent in advance using a kettle reactor, and then a reactor equipped with a devolatilizer, for example, heat exchange Preferred is a mode in which the cyclization condensation reaction is completed with a devolatilizer comprising a vessel and a devolatilization tank, an extruder with a vent, or the like. In particular, in the case of this form, it is more preferable that a catalyst for the cyclization condensation reaction is present.

  As described above, the hydroxyl group and ester group present in the molecular chain of the polymer (a) obtained in the polymerization step are preliminarily subjected to a cyclization condensation reaction to increase the cyclization condensation reaction rate to some extent. The method of carrying out the cyclization condensation reaction simultaneously using the volatilization process is a preferred form in obtaining the lactone ring-containing polymer in the present invention. With this form, a lactone ring-containing polymer having a higher glass transition temperature, a higher cyclization condensation reaction rate, and excellent heat resistance can be obtained. In this case, as a measure of the cyclization condensation reaction rate, for example, the mass reduction rate in the range of 150 to 300 ° C. in the dynamic TG measurement shown in the examples is preferably 2% or less, more preferably 1.5% or less. More preferably, it is 1% or less.

  The reactor that can be employed in the cyclization condensation reaction performed in advance before the cyclization condensation reaction using the devolatilization process at the same time is not particularly limited. For example, an autoclave, a kettle reactor, a heat exchanger And a devolatilizer comprising a devolatilization tank, and a vented extruder suitable for a cyclization condensation reaction using a devolatilization step at the same time can also be used. Of these reactors, an autoclave and a kettle reactor are particularly preferable. However, even when a reactor such as an extruder with a vent is used, the autoclave or kettle can be adjusted by adjusting the temperature conditions, barrel conditions, screw shape, screw operating conditions, etc. It is possible to carry out the cyclization condensation reaction in the same state as the reaction state in the type reactor.

  In the case of the cyclization condensation reaction carried out in advance before the cyclization condensation reaction using the devolatilization step at the same time, for example, a mixture containing the polymer (a) and the solvent obtained in the polymerization step is used as (i) a catalyst. And (ii) a method of performing a heat reaction without a catalyst, a method of performing the above (i) or (ii) under pressure, and the like.

  The “mixture containing the polymer (a) and the solvent” introduced into the cyclization condensation reaction in the lactone cyclization condensation step refers to the polymerization reaction mixture obtained in the polymerization step itself or once the solvent is removed. It means a mixture obtained by re-adding a solvent suitable for the cyclization condensation reaction later.

  The solvent that can be re-added in the cyclization condensation reaction that is carried out in advance before the cyclization condensation reaction using the devolatilization step at the same time is not particularly limited. For example, aromatic carbonization such as toluene, xylene, ethylbenzene, etc. Hydrogens; ketones such as methyl ethyl ketone and methyl isobutyl ketone; chloroform, dimethyl sulfoxide, tetrahydrofuran; and the like. These solvents may be used alone or in combination of two or more. It is preferable to use the same type of solvent as that used in the polymerization step.

  Examples of the catalyst to be added in the method (i) include commonly used esterification catalysts such as p-toluenesulfonic acid or transesterification catalysts, basic compounds, organic carboxylates, and carbonates. In the invention, it is preferable to use the aforementioned organophosphorus compound. The addition timing of the catalyst is not particularly limited. For example, the catalyst may be added at the beginning of the reaction, may be added during the reaction, or may be added in both of them. The addition amount of the catalyst is not particularly limited, but for example, is preferably 0.001 to 5% by mass, more preferably 0.01 to 2.5% by mass with respect to the mass of the polymer (a). More preferably, it is 0.01-1 mass%, Most preferably, it is 0.05-0.5 mass%. Although the heating temperature and heating time of method (i) are not particularly limited, for example, the heating temperature is preferably room temperature to 180 ° C., more preferably 50 to 150 ° C., and the heating time is preferably 1 to 20 hours, more preferably 2 to 10 hours. If the heating temperature is less than room temperature or the heating time is less than 1 hour, the cyclization condensation reaction rate may be lowered. Conversely, if the heating temperature exceeds 180 ° C. or the heating time exceeds 20 hours, the resin may be colored or decomposed.

  In the method (ii), for example, the polymerization reaction mixture obtained in the polymerization step may be heated as it is using a pressure-resistant kettle reactor or the like. Although the heating temperature and heating time of method (ii) are not particularly limited, for example, the heating temperature is preferably 100 to 180 ° C, more preferably 100 to 150 ° C, and the heating time is preferably 1 to 20 hours, more preferably 2 to 10 hours. When the heating temperature is less than 100 ° C. or the heating time is less than 1 hour, the cyclization condensation reaction rate may be lowered. Conversely, if the heating temperature exceeds 180 ° C. or the heating time exceeds 20 hours, the resin may be colored or decomposed.

  In any method, there is no problem even under pressure depending on conditions.

  In the case of the cyclization condensation reaction performed in advance before the cyclization condensation reaction using the devolatilization step at the same time, there is no problem even if part of the solvent volatilizes spontaneously during the reaction.

  The mass reduction rate within the range of 150 to 300 ° C. in the dynamic TG measurement at the end of the cyclization condensation reaction performed in advance before the cyclization condensation reaction simultaneously used in combination with the devolatilization step, that is, immediately before the start of the devolatilization step is Preferably it is 2% or less, More preferably, it is 1.5% or less, More preferably, it is 1% or less. When the mass reduction rate exceeds 2%, the cyclization condensation reaction rate does not rise to a sufficiently high level even if the cyclization condensation reaction is performed simultaneously with the devolatilization step, and the physical properties of the resulting lactone ring-containing polymer. May deteriorate. In addition, when performing said cyclization condensation reaction, in addition to a polymer (a), you may coexist other thermoplastic resins.

  The hydroxyl group and ester group present in the molecular chain of the polymer (a) obtained in the polymerization step are preliminarily subjected to a cyclization condensation reaction to increase the cyclization condensation reaction rate to some extent. In the case of the form in which the cyclized condensation reaction is performed, the polymer obtained by the cyclized condensation reaction performed in advance (the polymer in which at least a part of the hydroxyl group and the ester group present in the molecular chain is subjected to the cyclized condensation reaction) and the solvent May be introduced into the cyclization condensation reaction using the devolatilization step at the same time, and if necessary, the polymer (at least a part of the hydroxyl group and ester group present in the molecular chain is cyclized and condensed). You may introduce | transduce into the cyclocondensation reaction which used the devolatilization process together, after passing through other processes, such as adding a solvent again after isolating the polymer which reacted.

  The devolatilization step is not limited to being completed at the same time as the cyclization condensation reaction, and may be completed after a lapse of time from the completion of the cyclization condensation reaction.

  The weight average molecular weight of the lactone ring-containing polymer is preferably 1,000 to 2,000,000, more preferably 5,000 to 1,000,000, still more preferably 10,000 to 500,000, particularly preferably. 50,000 to 500,000. In addition, a weight average molecular weight is the value calculated | required by polystyrene conversion using gel permeation chromatography.

  The lactone ring-containing polymer preferably has a mass reduction rate in the range of 150 to 300 ° C. in dynamic TG measurement of 1% or less, more preferably 0.5% or less, and still more preferably 0.3% or less.

  Since the lactone ring-containing polymer has a high cyclization condensation reaction rate, it is possible to avoid the disadvantage that bubbles and silver streaks enter the molded product after molding. Furthermore, since the lactone ring structure is sufficiently introduced into the polymer due to the high cyclization condensation reaction rate, the obtained lactone ring-containing polymer has sufficiently high heat resistance.

  The lactone ring-containing polymer has a coloring degree (YI) of preferably 6 or less, more preferably 3 or less, still more preferably 2 or less, and particularly preferably 1 or less when a chloroform solution having a concentration of 15% by mass is used. . If the degree of coloring (YI) exceeds 6, transparency may be impaired by coloring, and it may not be used for the intended purpose.

  The lactone ring-containing polymer has a 5% mass reduction temperature in thermal mass spectrometry (TG) of preferably 330 ° C. or higher, more preferably 350 ° C. or higher, and still more preferably 360 ° C. or higher. The 5% mass reduction temperature in thermal mass spectrometry (TG) is an index of thermal stability, and if it is less than 330 ° C., sufficient thermal stability may not be exhibited.

  The lactone ring-containing polymer has a glass transition temperature (Tg) of preferably 115 ° C. or higher, more preferably 125 ° C. or higher, still more preferably 130 ° C. or higher, and particularly preferably 140 ° C. or higher.

  The total amount of residual volatile components contained in the lactone ring-containing polymer is preferably 1,500 ppm or less, more preferably 1,000 ppm or less. If the total amount of residual volatile components exceeds 1,500 ppm, it may be colored due to alteration during molding, foaming, or molding defects such as silver streak.

  The lactone ring-containing polymer has a total light transmittance of 85% or more, more preferably 88% or more, and still more preferably measured by a method based on ASTM-D-1003 for a molded product obtained by injection molding. 90% or more. The total light transmittance is an index of transparency, and if it is less than 85%, the transparency is lowered and it may not be used for the intended purpose.

  The content of the lactone ring-containing polymer in the thermoplastic resin film is preferably 50 to 100% by mass, more preferably 60 to 100% by mass, still more preferably 70 to 100% by mass, and particularly preferably 80 to 100% by mass. is there. When the content of the lactone ring-containing polymer in the thermoplastic resin film is less than 50% by mass, the effects of the present invention may not be sufficiently exhibited.

  The thermoplastic resin film containing a lactone ring-containing polymer as a main component contains a polymer other than the lactone ring-containing polymer (hereinafter sometimes referred to as “other polymer”) as another component. Also good. Examples of other polymers include olefin polymers such as polyethylene, polypropylene, ethylene-propylene copolymer, poly (4-methyl-1-pentene); halogens such as vinyl chloride, vinylidene chloride, and chlorinated vinyl resins. Acrylic polymers such as polymethyl methacrylate; Styrene polymers such as polystyrene, styrene-methyl methacrylate copolymer, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene block copolymer Polyesters such as polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate; polyamides such as nylon 6, nylon 66 and nylon 610; polyacetal; polycarbonate; polyphenylene oxide; Sulfides; polyetheretherketone; polysulfones; polyethersulfones; polyoxyethylene benzylidene alkylene; polyamideimide; polybutadiene rubber, rubber-like polymer such as ABS resin or ASA resin containing an acrylic rubber; and the like.

  The content of the other polymer in the thermoplastic resin film is preferably 0 to 50% by mass, more preferably 0 to 40% by mass, further preferably 0 to 30% by mass, and particularly preferably 0 to 20% by mass. .

  The thermoplastic resin film containing a lactone ring-containing polymer as a main component may contain various additives. Examples of additives include antioxidants such as hindered phenols, phosphorus, and sulfur; stabilizers such as light stabilizers, weather stabilizers, and heat stabilizers; reinforcing materials such as glass fibers and carbon fibers; phenyls UV absorbers such as salicylate, (2,2′-hydroxy-5-methylphenyl) benzotriazole, 2-hydroxybenzophenone; near infrared absorbers; tris (dibromopropyl) phosphate, triallyl phosphate, antimony oxide, etc. Flame retardants; Antistatic agents such as anionic, cationic and nonionic surfactants; Colorants such as inorganic pigments, organic pigments and dyes; Organic fillers and inorganic fillers; Resin modifiers; Organic fillers and inorganic fillers Agents, plasticizers, lubricants, antistatic agents, flame retardants, and the like.

  The content of the additive in the thermoplastic resin film containing a lactone ring-containing polymer as a main component is preferably 0 to 5% by mass, more preferably 0 to 2% by mass, and still more preferably 0 to 0.5% by mass. It is.

  A method for producing a thermoplastic resin film containing a lactone ring-containing polymer as a main component is not particularly limited. For example, a lactone ring-containing polymer and other polymers and additives are conventionally known. It is possible to form a film after sufficiently mixing with the mixing method in advance to obtain a thermoplastic resin composition in advance. Alternatively, the lactone ring-containing polymer and other polymers and additives may be made into separate solutions and mixed to form a uniform mixed solution, and then formed into a film.

  First, in order to produce a thermoplastic resin composition, for example, the above film raw material is pre-blended with a conventionally known mixer such as an omni mixer, and then the obtained mixture is extrusion kneaded. In this case, the mixer used for extrusion kneading is not particularly limited. For example, a conventionally known mixer such as an extruder such as a single screw extruder or a twin screw extruder or a pressure kneader may be used. it can.

  Examples of the film forming method include conventionally known film forming methods such as a solution casting method (solution casting method), a melt extrusion method, a calendar method, and a compression molding method. Among these film forming methods, the solution casting method (solution casting method) and the melt extrusion method are preferable.

  Examples of the solvent used in the solution casting method (solution casting method) include aromatic hydrocarbons such as benzene, toluene and xylene; aliphatic hydrocarbons such as cyclohexane and decalin; esters such as ethyl acetate and butyl acetate Ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone; alcohols such as methanol, ethanol, isopropanol, butanol, isobutanol, methyl cellosolve, ethyl cellosolve and butyl cellosolve; ethers such as tetrahydrofuran and dioxane; dichloromethane, Halogenated hydrocarbons such as chloroform and carbon tetrachloride; dimethylformamide; dimethyl sulfoxide; These solvents may be used alone or in combination of two or more.

  Examples of the apparatus for performing the solution casting method (solution casting method) include a drum casting machine, a band casting machine, and a spin coater.

  Examples of the melt extrusion method include a T-die method and an inflation method, and the molding temperature at that time is preferably 150 to 350 ° C., more preferably 200 to 300 ° C.

  When forming a film by the T-die method, a roll-shaped film can be obtained by attaching a T-die to the tip of a known single-screw extruder or twin-screw extruder and winding the film extruded into a film. it can. At this time, it is possible to perform uniaxial stretching by appropriately adjusting the temperature of the winding roll and adding stretching in the extrusion direction. Further, simultaneous biaxial stretching, sequential biaxial stretching, and the like can be performed by stretching the film in a direction perpendicular to the extrusion direction.

  The thermoplastic resin film containing a lactone ring-containing polymer as a main component may be either an unstretched film or a stretched film. In the case of a stretched film, either a uniaxially stretched film or a biaxially stretched film may be used. In the case of a biaxially stretched film, either a simultaneous biaxially stretched film or a sequential biaxially stretched film may be used. In the case of biaxial stretching, the mechanical strength is improved and the film performance is improved. The thermoplastic resin film containing a lactone ring-containing polymer as a main component can suppress an increase in retardation even when stretched by mixing other thermoplastic resins, and retains optical isotropy. be able to.

  The stretching temperature is preferably in the vicinity of the glass transition temperature of the thermoplastic resin composition that is the film raw material, and specifically, preferably (glass transition temperature-30 ° C) to (glass transition temperature + 100 ° C), more preferably. Is within the range of (glass transition temperature−20 ° C.) to (glass transition temperature + 80 ° C.). If the stretching temperature is less than (glass transition temperature-30 ° C.), a sufficient stretching ratio may not be obtained. Conversely, when the stretching temperature exceeds (glass transition temperature + 100 ° C.), the resin composition may flow, and stable stretching may not be performed.

  The draw ratio defined by the area ratio is preferably in the range of 1.1 to 25 times, more preferably 1.3 to 10 times. If the draw ratio is less than 1.1 times, the toughness accompanying the drawing may not be improved. On the other hand, when the draw ratio exceeds 25 times, the effect of increasing the draw ratio may not be recognized.

  The stretching speed is unidirectional, preferably 10 to 20,000% / min, more preferably 100 to 10,000% / min. When the stretching speed is less than 10% / min, it takes time to obtain a sufficient stretching ratio, and the production cost may increase. On the contrary, when the stretching speed exceeds 20,000% / min, the stretched film may be broken.

  In addition, the film which has a lactone ring containing polymer as a main component can perform heat processing (annealing) etc. after an extending | stretching process in order to stabilize the optical isotropy and mechanical characteristics. The conditions for the heat treatment may be appropriately selected similarly to the conditions for the heat treatment performed on a conventionally known stretched film, and are not particularly limited.

  The thickness of the thermoplastic resin film containing a lactone ring-containing polymer as a main component is preferably 5 to 200 μm, more preferably 10 to 100 μm. When the thickness is less than 5 μm, not only the strength of the film is lowered, but also when the durability test of the polarizing plate is conducted, the crimp may be increased. On the other hand, when the thickness exceeds 200 μm, not only the transparency of the film is lowered, but also the moisture permeability becomes small, and when a water-based adhesive is used, the drying speed of the solvent water may be slow. .

  The thermoplastic resin film containing the lactone ring-containing polymer as a main component has a surface wetting tension of preferably 40 mN / m or more, more preferably 50 mN / m or more, and even more preferably 55 mN / m or more. When the surface wetting tension is at least 40 mN / m or more, the adhesive strength between the thermoplastic resin film containing the lactone ring-containing polymer as a main component and the polarizer is further improved. In order to adjust the surface wetting tension, for example, corona discharge treatment, plasma treatment, ozone spraying, ultraviolet irradiation, flame treatment, chemical treatment, and other conventionally known surface treatments can be performed.

≪Polarizer≫
The polyvinyl alcohol resin constituting the polarizer can be obtained by saponifying a polyvinyl acetate resin. Examples of the polyvinyl acetate resin include, in addition to polyvinyl acetate, which is a homopolymer of vinyl acetate, for example, a copolymer of vinyl acetate and other monomers copolymerizable therewith. Examples of other monomers copolymerized with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, and unsaturated sulfonic acids. The degree of saponification of the polyvinyl alcohol resin is usually 85 to 100 mol%, preferably 98 to 100 mol%. This polyvinyl alcohol-based resin may be further modified, and for example, polyvinyl formal or polyvinyl acetal modified with aldehydes may be used. The degree of polymerization of the polyvinyl alcohol-based resin is usually 1,000 to 10,000, preferably 1,100 to 10,000.

  The polarizer is, for example, a step of uniaxially stretching a polyvinyl alcohol-based resin film, a step of dyeing the uniaxially stretched film with a dichroic dye, and adsorbing the dichroic dye to the film, The step of treating the adsorbed uniaxially stretched film with a boric acid aqueous solution, the step of washing with water after the treatment with the boric acid aqueous solution, and the uniaxially stretched film on which the dichroic dye is subjected to adsorption orientation by performing these steps It is manufactured through a process of pasting a protective film.

  Uniaxial stretching may be performed before dyeing with a dichroic dye, may be performed simultaneously with dyeing with a dichroic dye, or may be performed after dyeing with a dichroic dye. When uniaxial stretching is performed after dyeing with a dichroic dye, this uniaxial stretching may be performed before boric acid treatment or during boric acid treatment. Of course, it is also possible to perform uniaxial stretching in these plural stages. For uniaxial stretching, rolls having different peripheral speeds may be uniaxially stretched or uniaxially stretched using a hot roll. Moreover, the dry-type extending | stretching which extends | stretches in air | atmosphere may be sufficient, and the wet extending | stretching which extends | stretches in the state swollen in the bath containing the organic solvent compatible with water or water may be sufficient. The draw ratio is usually about 4 to 8 times.

  In order to dye the polyvinyl alcohol resin film with the dichroic dye, for example, the polyvinyl alcohol resin film may be immersed in an aqueous solution containing the dichroic dye. Specifically, iodine or a dichroic dye is used as the dichroic dye.

  When iodine is used as the dichroic dye, a method of dyeing a polyvinyl alcohol-based resin film in an aqueous solution containing iodine and potassium iodide is usually employed. The iodine content in this aqueous solution is usually about 0.01 to 0.5 parts by mass per 100 parts by mass of water, and the potassium iodide content is usually 0.5 to 10 parts by mass per 100 parts by mass of water. About a part. The temperature of this aqueous solution is usually about 20 to 40 ° C., and the immersion time in this aqueous solution is usually about 30 to 300 seconds.

On the other hand, when a dichroic dye is used as the dichroic dye, a method of immersing and dyeing a polyvinyl alcohol-based resin film in an aqueous solution containing a water-soluble dichroic dye is usually employed. The content of the dichroic dye in this aqueous solution is usually about 1 × 10 ⁻³ to 1 × 10 ⁻² parts by mass per 100 parts by mass of water. This aqueous solution may contain an inorganic salt such as sodium sulfate. The temperature of this aqueous solution is usually about 20 to 80 ° C., and the immersion time in this aqueous solution is usually about 30 to 300 seconds.

  The boric acid treatment after dyeing with a dichroic dye is performed by immersing the dyed polyvinyl alcohol resin film in an aqueous boric acid solution. The boric acid content in the boric acid aqueous solution is usually about 1 to 15 parts by mass, preferably about 2 to 12 parts by mass per 100 parts by mass of water. When iodine is used as the dichroic dye, the boric acid aqueous solution preferably contains potassium iodide. The content of potassium iodide in the boric acid aqueous solution is usually about 2 to 20 parts by mass, preferably about 5 to 15 parts by mass per 100 parts by mass of water. The immersion time in the boric acid aqueous solution is usually about 100 to 1,200 seconds, preferably about 150 to 600 seconds, and more preferably about 200 to 400 seconds. The temperature of the boric acid aqueous solution is usually 50 ° C. or higher, preferably about 50 to 85 ° C.

  The polyvinyl alcohol resin film after the boric acid treatment is usually washed with water. The water washing treatment is performed, for example, by immersing a boric acid-treated polyvinyl alcohol resin film in water. After washing with water, a drying process is performed to obtain a polarizer. The temperature of water in the water washing treatment is usually about 5 to 40 ° C., and the immersion time is usually about 2 to 120 seconds. The drying process performed after that is normally performed using a hot air dryer or a far-infrared heater. A drying temperature is about 20-100 degreeC normally. The drying time is usually about 120 to 600 seconds.

≪Easily adhesive layer≫
In the polarizing plate of the present invention, when the polarizer and the protective film are bonded with an adhesive, the protective film is provided with an easy-adhesion layer on the surface of the protective film facing the polarizer, and the polarizer and the protective film Adhesive strength is improved.

  The easy adhesion layer provided on the surface of the protective film facing the polarizer is a polyurethane resin composition (a composition containing a polyurethane resin and / or a precursor that gives a polyurethane resin after the reaction on the surface of the protective film facing the polarizer). ) And / or a resin composition containing an amino group-containing polymer (hereinafter sometimes referred to as “easily adhesive layer coating composition”), and then dried, cured, or dried.

  The thickness of the easy-adhesion layer is the thickness after drying / curing or drying, for example, preferably 0.01 to 10 μm, more preferably 0.05 to 3 μm, and still more preferably 0.1 to 1 μm. When the thickness of the easy adhesion layer is less than 0.01 μm, the adhesive strength between the polarizer and the protective film may be insufficient. On the other hand, when the thickness of the easy-adhesion layer exceeds 10 μm, color loss or discoloration of the polarizing plate may easily occur in the water resistance or moisture resistance test.

  The method of applying the easy-adhesion layer coating composition to the surface of the protective film facing the polarizer may be a normal coating technique using a bar coater, roll coater, gravure coater, etc., and is not particularly limited. Absent. Further, the method and conditions for drying the applied easy-adhesion layer coating composition are not particularly limited. For example, using a hot air dryer or an infrared dryer, preferably 50 to 130 ° C., more preferably What is necessary is just to dry at the temperature of 75-110 degreeC. Moreover, there is no problem even if a curing step is provided for the urethane bond formation reaction and / or curing of the easy-adhesion layer coating composition. When a curing process is required, the curing temperature is preferably 20 to 100 ° C., more preferably 20 to 50 ° C., but it proceeds to some extent with the heat used for drying the composition, and an adhesive is used. Since the process proceeds further in the bonding process between the polarizer and the protective film, sufficient physical properties can be obtained even at room temperature curing.

  In addition, in order to adjust the surface wetting tension, the surface of the easy-adhesion layer of the protective film provided with the easy-adhesion layer is subjected to, for example, corona discharge treatment, plasma treatment, ozone spraying, before the subsequent adhesion step, Ultraviolet irradiation, flame treatment, chemical treatment, and other conventionally known surface treatments can be performed.

<Polyurethane resin>
“Polyurethane resin” used in the easy-adhesion layer coating composition means a resin obtained by reacting a polyisocyanate component with an active hydrogen component such as polyol, polyamine, or water, and the reaction is completed before application. What is currently used may be used, and what reacts during and / or after application to become a polyurethane resin may be used. As the polyurethane resin, a conventionally known polyurethane resin used for paints, adhesives, coatings and the like can be used. For example, a two-part polyurethane resin containing a polyol and an isocyanate curing agent, a one-part type Examples of the polyurethane resin include one-component moisture-curable polyurethane resin. These polyurethane resins may be used alone or in combination of two or more.

  The polyurethane resin compositions exemplified above are preferably all solvent-based. Each polyurethane resin composition is finally made into an easy-adhesion layer coating composition by adjusting the non-volatile content to a predetermined concentration with a solvent. As a density | concentration of a non volatile matter, Preferably it is 1-30 mass% with respect to the whole composition, More preferably, it is 5-15 mass%. The solvent that can be used is not particularly limited as long as the components constituting each composition are dissolved. For example, toluene, xylene, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, butyl acetate, propylene glycol Examples thereof include monomethyl ether acetate. These solvents may be used alone or in combination of two or more.

  The polyurethane resin composition includes, for example, a coupling agent such as a silane coupling agent or a titanium coupling agent; a tackifier such as a terpene resin, a phenol resin, a terpene-phenol resin, a rosin resin, or a xylene resin; Conventional additives known in the art such as agents; ultraviolet absorbers, antioxidants, heat stabilizers, hydrolysis stabilizers, etc .; antifoaming agents; plasticizers; inorganic fillers;

<Two-component polyurethane resin composition>
The two-pack type polyuretan resin composition contains a polyol and an isocyanate curing agent as precursors in a solvent, and is applied to the surface of the protective film facing the polarizer, and then dried and cured to form polyurethane. An easy adhesion layer containing a resin is formed. Curing is performed by reacting the polyol and the isocyanate curing agent with heat to form a polyurethane resin. Here, examples of the polyol include polyacryl polyol, polyester polyol, polyether polyol, polyurethane polyol, castor oil, polybutadiene polyol, and epoxy resin. These polyols may be used alone or in combination of two or more.

  The polyacryl polyol can be produced by copolymerizing a copolymerizable monomer having a hydroxyl group with (meth) acrylic acid ester which is a main component. Examples of the copolymerizable monomer having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and (meth) acrylic. Hydroxyalkyl esters of (meth) acrylic acid, such as 2-hydroxybutyl acid, 4-hydroxybutyl (meth) acrylate, 2-hydroxypentyl (meth) acrylate; polyhydric alcohols such as glycerin and trimethylolpropane (meta ) Acrylic acid monoester; N-methylol (meth) acrylamide; and the like. These copolymerizable monomers having a hydroxyl group may be used alone or in combination of two or more.

  Examples of the (meth) acrylic acid ester include methyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, and the like. Moreover, the said monomer component may contain the other unsaturated monomer as needed. Other unsaturated monomers are not particularly limited as long as they can be copolymerized, and examples thereof include unsaturated monocarboxylic acids such as (meth) acrylic acid; unsaturated dicarboxylic acids such as maleic acid. Acids 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 such as vinyl acetate and vinyl propionate Esters; 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 such as styrene and α-methylstyrene , Β-unsaturated aromatic monomers; and the like. These unsaturated monomers may be used alone or in combination of two or more.

  The polyester polyol can be produced by reacting a polybasic acid component and a polyol component so that the hydroxyl group of the polyol component becomes excessive with respect to the carboxyl group of the polybasic acid component. Preferably, a linear polyester polyol composed of a dibasic acid component and a diol component is used. In addition, examples of the polyester polyol include poly β-methyl-δ-valerolactone, polycaprolactone, and polycarbonate diol.

  Dibasic acid components include aromatic dicarboxylic acids such as orthophthalic acid, isophthalic acid and terephthalic acid; alicyclic rings such as hexahydrophthalic acid, tetrahydrophthalic acid, 1,3-cyclohexanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid Formula dicarboxylic acids; aliphatic dicarboxylic acids such as oxalic acid, succinic acid, malonic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, dodecanedicarboxylic acid, octadecanedicarboxylic acid; And dicarboxylic acid anhydrides, lower alcohol esters, and the like.

  Examples of the diol component include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, polypropylene glycol, 1,4-cyclohexanedimethanol, 1,4-cyclohexanediol, bisphenol A, bisphenol F , Hydrogenated bisphenol A, hydrogenated bisphenol F, and the like.

  As a method for producing a polyester polyol from a dibasic acid component and a diol component, a general polyester production method except that the hydroxyl group of the diol component is excessive with respect to the carboxyl group of the dibasic acid component Can be adopted. As the catalyst, a general esterification catalyst can be used, and examples thereof include dibutyltin oxide, zinc acetate, titanium tetrabutoxide, and antimony trioxide.

  The polyether polyol can be produced by adding an alkylene oxide to a polyhydric alcohol by ring-opening polymerization. Examples of the polyhydric alcohol include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, glycerin, trimethylolpropane, and the like. These polyhydric alcohols may be used alone or in combination of two or more. Examples of the alkylene oxide include ethylene oxide, propylene oxide, butylene oxide, styrene oxide, and tetrahydrofuran. These alkylene oxides may be used alone or in combination of two or more.

  The polyurethane polyol is obtained by reacting a polyol and a polyisocyanate compound so that the hydroxyl group of the polyol is excessive with respect to the isocyanate group of the polyisocyanate compound, and has a hydroxyl group at the terminal. As the polyurethane polyol, polyacrylic polyurethane polyol, polyester polyurethane polyol, polyether obtained by using polyacryl polyol, polyester polyol, polyether polyol or the like (hereinafter sometimes referred to as “polymer polyol”) as the polyol. Based polyurethane polyols and the like.

  Examples of the polyisocyanate compound include 1,5-naphthalene diisocyanate, 4,4′-diphenylmethane diisocyanate, 4,4′-diphenyldimethylmethane diisocyanate, tetramethyldiphenylmethane diisocyanate, 1,3-phenylene diisocyanate, and 1,4-phenylene. Diisocyanate, 2-chloro-1,4-phenyl diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, butane-1,4-diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene Diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, cyclohexane-1,4-diisocyanate, xylylene diisocyanate, isophorone diiso Anate, dicyclohexylmethane-4,4′-diisocyanate, 1,3-bis (isocyanate methyl) cyclohexane, methylcyclohexane diisocyanate, 4,4′-diphenyl ether diisocyanate, 4,4′-diphenyl sulfoxide diisocyanate, 4,4′-diphenyl Examples include sulfone diisocyanate, 4,4′-biphenyl diisocyanate, and derivatives thereof.

  As a method for producing a polyurethane polyol from a polymer polyol and a polyisocyanate compound, a general polyurethane production method is performed except that the hydroxyl group of the polymer polyol is reacted in excess with respect to the isocyanate group of the polyisocyanate compound. Can be adopted.

  The polyurethane polyol can also contain a chain extender or a polymerization terminator as a constituent component. Examples of chain extenders include diamines such as ethylenediamine, propylenediamine, hexamethylenediamine, isophoronediamine, dicyclohexylmethane-4,4′-diamine; ethylene glycol, 1,2-propanediol, 1,3-butanediol. 1,4-butanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, 1,4-cyclohexanedimethanol, 2,2-dimethylol And diols such as propionic acid. Examples of the polymerization terminator include alkyl monoamines such as di-n-butylamine and mono-n-butylamine.

  In the two-component polyurethane resin composition, the number average molecular weight of the polymer polyol is preferably 300 to 100,000, more preferably 1,000 to 30,000. The number average molecular weight of the polyurethane polyol is preferably 1,000 to 100,000, more preferably 5,000 to 50,000. In addition, a number average molecular weight is the value calculated | required by polystyrene conversion using gel permeation chromatography.

  As an isocyanate type hardening | curing agent, said polyisocyanate compound can be used, for example. Furthermore, modified products derived from these polyisocyanate compounds, such as dimers, trimers (isocyanurates), polymeric MDI, adducts with trimethylolpropane, biurets, allophanates, urea modified products, and the like can be mentioned. It is done. The isocyanate-based curing agent may be one in which the terminal isocyanate group is protected with oxime or lactam. In this case, by heating, the protecting group is detached from the isocyanate group, and the isocyanate group reacts.

  In the two-component polyurethane resin composition, the amount of the isocyanate-based curing agent is, for example, preferably 3 to 300 parts by weight, more preferably 5 to 200 parts by weight, and more preferably 100 parts by weight as a solid. Preferably it is 10-100 mass parts.

  The two-component polyurethane resin composition can contain a chain extender as a constituent component. Examples of the chain extender include trifunctional or higher functional polyols such as trimethylolpropane and glycerin in addition to the diamines and diols listed above when explaining polyurethane polyols. Further, a two-component polyurethane resin composition comprising a polyol and / or a polyol of the chain extender and an isocyanate-terminated urethane prepolymer (hereinafter sometimes referred to as “NCO-terminated prepolymer”) can also be constituted.

  In order to improve the reactivity of the isocyanate curing agent, a reaction catalyst may be added to the two-component polyurethane resin composition. Although it does not specifically limit as a reaction catalyst, For example, tin-type catalysts, such as tin octenoate, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin thiocarboxylate, dibutyltin dimaleate, dioctyltin thiocarboxylate; N, N-dimethylcyclohexylamine, N, N, N ′, N′-tetramethylethylenediamine, triethylenediamine, N, N′-dimethylpiperazine, quinuclidine, N-methylmorpholine, dimorpholinodiethyl ether, dimethylaminoethanol, etc. Amine-based catalysts; and the like. These reaction catalysts may be used alone or in combination of two or more. The compounding amount of the reaction catalyst is, for example, preferably 0.01 to 10 parts by mass, more preferably 0.1 to 5 parts by mass with respect to 100 parts by mass of the isocyanate curing agent.

<One-component polyurethane resin composition>
The one-component polyurethane resin composition contains a polyurethane resin in a solvent, and is applied to the surface of the protective film facing the polarizer, and then dried to form an easy-adhesion layer containing the polyurethane resin. This one-component polyurethane resin composition is a so-called lacquer type that does not particularly require a reaction. Here, examples of the polyurethane resin include polyacrylic polyurethane resins, polyester polyurethane resins, and polyether polyurethane resins. These urethane resins may be used alone or in combination of two or more.

  These polyurethane resins can be produced by reacting polyacryl polyol, polyester polyol or polyether polyol with a polyisocyanate compound. These polyurethane resins are produced by reacting such that the hydroxyl group of the polyol containing polyacryl polyol, polyester polyol or polyether polyol and the isocyanate group of the polyisocyanate compound are approximately equivalent or the hydroxyl group is slightly excessive. be able to. However, in order to obtain a high molecular weight body, it is preferable to carry out the reaction as close to the equivalent as possible. Here, the polyacryl polyol, the polyester polyol, and the polyether polyol are obtained as described in the case of the two-component polyurethane resin composition, for example. Examples of the polyisocyanate compound include the polyisocyanate compounds and isocyanate curing agents as described above in the case of a two-component polyurethane resin composition. Moreover, also about a catalyst, a chain extender, etc., the above catalyst, chain extender, etc. which were enumerated in the case of a 2 liquid type polyurethane resin composition are mentioned, for example.

  In the one-component polyurethane resin composition, the number average molecular weight of the polyurethane resin is preferably 10,000 to 100,000, more preferably 20,000 to 50,000. In addition, a number average molecular weight is the value calculated | required by polystyrene conversion using gel permeation chromatography.

<One-component moisture-curable polyurethane resin composition>
The one-component moisture-curable polyurethane resin composition contains an NCO-terminated urethane prepolymer as a precursor in a solvent, and is applied to the surface of the protective film facing the polarizer, and then dried and cured. An easy adhesion layer containing a polyurethane resin is formed. Curing is carried out by reacting moisture in the atmosphere or moisture in the protective film with the NCO-terminated urethane prepolymer to form urea and / or biuret, thereby forming polyurethane urea and / or polyurethane biuret.

  The NCO-terminated urethane prepolymer can be produced by reacting a polyisocyanate compound with a polyol. This NCO-terminated urethane prepolymer is obtained by reacting the polyisocyanate compound so that the isocyanate group of the polyisocyanate compound is excessive with respect to the hydroxyl group of the polyol, and has an isocyanate group at the terminal.

  Examples of the polyol include low molecular polyols, polyether polyols, polyester polyols, polyacryl polyols, castor oil, polybutadiene polyols and the like used for the chain extender described in the case of the two-component polyurethane resin composition. In particular, a polyol having a number average molecular weight of preferably 500 to 10,000, more preferably 1,000 to 5,000 is preferably a main component, and specifically, polypropylene glycol, castor oil, and the like are preferable.

  Examples of the polyisocyanate compound include the polyisocyanate compounds and isocyanate curing agents described above for the two-component polyurethane composition. Of these polyisocyanate compounds and isocyanate curing agents, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate (MDI), polymeric MDI, and the like are particularly suitable. Examples of the catalyst for accelerating the reaction between the polyol and the isocyanate compound include the above-mentioned catalysts enumerated in the case of a two-component polyurethane composition.

  In the one-component moisture-curable polyurethane resin composition, the number average molecular weight of the NCO-terminated urethane prepolymer is preferably 500 to 10,000, more preferably 1,000 to 5,000. In addition, a number average molecular weight is the value calculated | required by polystyrene conversion using gel permeation chromatography.

  The easy-adhesion layer coating composition containing a polyurethane resin is less likely to cause color loss or discoloration of the polarizing plate in a water resistance or moisture resistance test; it has a hydroxyl group or an isocyanate group as a reactive group even after the easy adhesion layer is formed. Therefore, it is excellent in the point of showing strong adhesiveness; having high water resistance and chemical resistance.

<Amino group-containing polymer>
As the amino group-containing polymer used in the easy-adhesion layer coating composition, a polymer having an amino group in the molecule can be used without particular limitation. For example, a polyalkyleneimine (a polymer having a primary amino group at the terminal and a secondary amino group and / or a tertiary amino group in the main chain) itself or a polyalkyleneimine in the side chain, etc. Good. In particular, a polymer having a primary amino group and / or secondary amino group in the side chain is preferred, and the primary amino group and / or secondary amino group is represented by the following formula (4):

[Wherein R ⁷ , R ⁸ , R ⁹ , R ¹⁰ and R ¹¹ are each independently a hydrogen atom, halogen atom, alkyl group, aralkyl group or aryl group, or cyano, halo, amino, hydroxy, Represents an alkyl group, an aralkyl group or an aryl group substituted with alkoxy or carboalkoxy, a is 0 or 1, and n is an integer of 1 or more.
It is preferable that it is group shown by these.

  As a method for producing a polymer having a primary amino group and / or a secondary amino group in the side chain, for example, (1) all or part of the carboxyl groups of the polymer having a carboxyl group may be converted to a primary amino group and / or A method of producing by modifying to a secondary amino group; (2) A glycidyl group of a polymer obtained by polymerizing a monomer component containing an unsaturated monomer having a glycidyl group such as glycidyl (meth) acrylate is ammonia. Or a method of producing a primary amino group and / or a secondary amino group by modification with an amine compound; (3) an unsaturated monomer having a glycidyl group such as glycidyl (meth) acrylate with ammonia or an amine compound; Modified and primary amino groups and / or secondary amino groups such as allylamine and aminoethyl (meth) acrylate How prepared by polymerizing a monomer component containing a monomer having; and the like. Of these methods, the method (1) is particularly suitable.

  Specific examples of the method (1) include a method in which a polymer having a carboxyl group is modified with a polyamine such as an alkyleneimine or a polyoxyalkylene polyamine. Here, examples of the polymer having a carboxyl group include acrylic resins, polyester resins, polyurethane resins, and polyolefin resins. These amino group-containing polymers may be used alone or in combination of two or more. Of these amino group-containing polymers, acrylic resins modified with alkyleneimine are particularly suitable.

  The polymer having a carboxyl group can be produced by polymerizing a monomer component containing at least one unsaturated carboxylic acid. Examples of the unsaturated carboxylic acid include unsaturated monocarboxylic acids such as (meth) acrylic acid, cinnamic acid, and crotonic acid; unsaturated dicarboxylic acids such as maleic acid, itaconic acid, and fumaric acid, and monoesters thereof. These unsaturated carboxylic acids may be used alone or in combination of two or more. In addition, the usage-amount of unsaturated carboxylic acid in the said monomer component becomes like this. Preferably it is 2-30 mass% with respect to all the monomer components, More preferably, it is 5-15 mass%.

  The monomer component may contain other unsaturated monomers as required in addition to the unsaturated carboxylic acid. The other unsaturated monomer is not particularly limited as long as it is an unsaturated monomer copolymerizable with an unsaturated carboxylic acid and does not react with a carboxyl group. For example, (meth) acrylic (Meth) acrylic acid esters such as methyl acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate; unsaturated nitriles such as (meth) acrylonitrile; (meth) acrylamide, N-methylol (meth) Unsaturated amides such as acrylamide; Vinyl esters such as vinyl acetate and vinyl propionate; Vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; α-olefins such as ethylene and propylene; Vinyl chloride, vinylidene chloride, vinyl fluoride, etc. Halogenated α, β-unsaturated aliphatic monomers; styrene, α- α such as methylstyrene, beta-unsaturated aromatic monomers such; and the like. These unsaturated monomers may be used alone or in combination of two or more.

  A polymer having a carboxyl group is produced by polymerizing a monomer component. As the polymerization method, conventionally known polymerization methods such as solution polymerization, emulsion polymerization, suspension polymerization and the like can be applied. The polymerization conditions such as polymerization temperature and polymerization time in the polymerization may be appropriately set according to the polymerization method to be applied, and are not particularly limited. At this time, if necessary, the degree of polymerization may be controlled using a chain transfer agent such as a mercaptan compound.

  The weight average molecular weight of the polymer having a carboxyl group is preferably 10,000 to 200,000, more preferably 30,000 to 150,000.

  Examples of the method for modifying the carboxyl group of a polymer having a carboxyl group into a primary amino group and / or a secondary amino group include a method using an alkyleneimine and a method using a polyamine such as a polyoxyalkylene polyamine as described above. In the present invention, a method of modifying with an alkyleneimine is preferably applied.

  In the polymer having a carboxyl group, the alkylene imine used when the carboxyl group is modified to an amino group is, for example, the following formula (5):

[Wherein R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ and R ¹⁶ are each independently a hydrogen atom, a halogen atom, an alkyl group, an aralkyl group or an aryl group, or cyano, halo, amino, hydroxy, Represents an alkoxy, carboalkoxy-substituted alkyl, aralkyl or aryl group]
Specifically, for example, ethyleneimine, 1,2-propyleneimine, 1,2-dodecyleneimine, 1,1-dimethylethyleneimine, phenylethyleneimine, benzylethyleneimine, hydroxyethylethyleneimine Aminoethylethyleneimine, 2-methylpropyleneimine, 3-chloropropylethyleneimine, methoxyethylethyleneimine, dodecylaziridinyl formate, N-ethylethyleneimine, N- (2-aminoethyl) ethyleneimine, N- (Phenethyl) ethyleneimine, N- (2-hydroxyethyl) ethyleneimine, N- (cyanoethyl) ethyleneimine, N-phenylethyleneimine, N- (p-chlorophenyl) ethyleneimine and the like can be mentioned. These alkyleneimines may be used alone or in combination of two or more. Of these alkyleneimines, ethyleneimine and 1,2-propyleneimine are particularly suitable.

  When the carboxyl group is modified using the alkyleneimine, a group in which the primary amino group and / or the secondary amino group represented by the above formula (4) is bonded to the —COO— group, that is, the following formula (6):

[Wherein R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ and n are the same as those in the above formula (4), and a is 1]
A group represented by Theoretically, n is an integer of 1 or more. However, in the reaction between a carboxyl group and an alkyleneimine, one carboxyl group has an alkylene regardless of the ratio of the carboxyl group to the alkyleneimine during the reaction. A product having a distribution including one molecule of imine reacted and one molecule reacted with two or more molecules is obtained. Therefore, on average, n will exceed 1.

  In the polymer having a carboxyl group, the amount of the carboxyl group modified with alkyleneimine is, for example, preferably 1 to 100 of unsaturated carboxylic acids contained in the monomer component in a proportion of 2 to 30% by mass. It is 10 mass%, More preferably, it is 10-100 mass%.

  The method and conditions for modifying the polymer having a carboxyl group with alkyleneimine are not particularly limited, and any conventionally known methods and conditions may be appropriately selected and employed.

  Thus, the amino group-containing polymer thus obtained is finally adjusted to a predetermined concentration with a solvent and / or water so that the non-volatile content becomes a predetermined concentration to obtain an easy-adhesion layer coating composition. The usage form of the easy-adhesion layer coating composition may be either solvent-based or aqueous (water-dispersed, water-soluble), but is preferably solvent-based. As a density | concentration of a non volatile matter, Preferably it is 1-30 mass% with respect to the whole composition, More preferably, it is 5-15 mass%. The solvent that can be used is not particularly limited as long as the components constituting each composition are dissolved. For example, toluene, xylene, acetone, methyl ethyl ketone, methyl isobutyl kitten, ethyl acetate, butyl acetate, isopropyl alcohol Etc. These solvents may be used alone or in combination of two or more.

  The easy adhesion layer coating composition containing an amino group-containing polymer includes, for example, coupling agents such as silane coupling agents and titanium coupling agents; leveling agents; ultraviolet absorbers, antioxidants, heat stabilizers, A conventionally known additive such as a stabilizer such as a hydrolysis-resistant stabilizer; an antifoaming agent; a plasticizer; an inorganic filler;

  The easy-adhesion layer coating composition containing an amino group-containing polymer has a good adhesion to various substrates because the primary and / or secondary amino groups of the amino group-containing polymer have good adhesion to various substrates. Good adhesion to the agent.

≪Adhesive≫
In the polarizing plate of this invention, since the easily bonding layer containing a polyurethane resin and / or an amino group containing polymer is formed in the surface facing the polarizer of a protective film, a polarizing plate and a protective film are bonded together. In doing so, it is not necessary to use a special adhesive. Therefore, an adhesive used in a conventionally known polarizing plate may be used, and is not particularly limited. Specifically, for example, a PVA adhesive, a polyurethane adhesive, and an acrylic adhesive are used. And isocyanate adhesives. These adhesives may be used alone or in combination of two or more. Of these adhesives, polyurethane adhesives and isocyanate adhesives are particularly suitable. The form of the adhesive is not particularly limited, and various forms of adhesives such as solvent-based, water-based, and solvent-free systems can be used, for example.

<Polyurethane adhesive>
Polyurethane adhesives are generally classified into two-part adhesives and one-part adhesives. Examples of the two-component adhesive include an adhesive that reacts a polyol and an isocyanate curing agent to generate a urethane bond and cure. On the other hand, examples of the one-component adhesive include a lacquer type one-component polyurethane adhesive, a one-component moisture-curable polyurethane adhesive, and the like.

  Specific examples of these polyurethane adhesives include, for example, a polyurethane resin composition for forming an easy-adhesion layer (for example, a two-component polyurethane resin composition, a one-component polyurethane resin composition, and a one-component moisture curing). Examples of the polyurethane resin composition described above when explaining the type polyurethane resin composition). The polyurethane adhesive is a polyurethane resin composition for further forming an easy-adhesion layer on the polyurethane adhesive described above in order to improve physical properties such as water resistance, heat resistance, and heat and humidity resistance. It is also possible to add a curing agent such as the above-mentioned isocyanate-based curing agent or epoxy-based curing agent.

  Examples of the polyurethane adhesive using an epoxy curing agent include, for example, the above-described polyurethane polyol enumerated when the one-component polyurethane resin composition for forming an easy-adhesion layer is described, and an epoxy curing agent. And polyurethane adhesives composed of The epoxy curing agent is not particularly limited as long as it is a compound having at least two epoxy groups. For example, glycidyl ether and glycidyl ester having at least two glycidyloxy groups are preferable, and glycidyl Ether is particularly preferred. In addition, an epoxy resin can be used as an epoxy curing agent. The usage-amount of an epoxy-type hardener becomes like this. Preferably it is 3-100 mass parts with respect to 100 mass parts of polyurethane polyols as solid content, More preferably, it is 10-50 mass parts. In order to improve the reactivity of the epoxy group of the epoxy curing agent, a reaction catalyst may be used.

  The polyurethane adhesive is usually solvent-based or water-based. In the case of a solvent-based adhesive, for example, it is used in the form of a solution, and in the case of an aqueous system, it is used in the form of an aqueous solution, an emulsion, or a colloidal dispersion. In the case of a solvent system, usable organic solvents are not particularly limited as long as the components constituting the adhesive are uniformly dissolved. For example, toluene, xylene, acetone, methyl ethyl ketone, methyl isobutyl ketone, acetic acid Examples include ethyl, butyl acetate, and propylene glycol monomethyl ether acetate. These solvents may be used alone or in combination of two or more. In addition, even in the case of an aqueous system, in addition to water, for example, alcohols such as n-butyl alcohol and isopropyl alcohol; ketones such as acetone;

  In the case of producing a water-based polyurethane adhesive, a conventionally known method can be applied. As a method for making a polyurethane adhesive aqueous, for example, a method of emulsifying using a dispersing agent such as an anionic, cationic, nonionic or zwitterionic surfactant (the one obtained by this method is referred to as “ ), Polyurethane resins, polyols, isocyanate curing agents, and epoxy curing agents have low reactivity with isocyanate groups such as carboxylates, sulfonates, and quaternary ammonium salts. Examples thereof include a method of introducing a functional group or a hydrophilic group such as polyethylene glycol and self-emulsifying (the product obtained by this method is sometimes referred to as “self-emulsifying type”). Examples of the water-based polyurethane adhesive include, for example, a one-component type composed of an aqueous polyurethane resin, an aqueous polyurethane resin and an isocyanate curing agent and / or an epoxy curing agent, and an aqueous polyol and an isocyanate type. Examples include a two-component type in which a curing agent and the like are combined. In particular, a polyurethane resin stably dispersed or dissolved in water, that is, an aqueous polyurethane resin used for an aqueous polyurethane adhesive, is preferably a self-emulsifying type because the aqueous solution or aqueous dispersion has good stability. .

  The method for producing the self-emulsifying aqueous polyurethane resin may be any conventionally known method and is not particularly limited. For example, (1) when synthesizing a polyurethane polymer, a sulfonic acid group, amino By copolymerizing an ionic hydrophilic group-containing compound containing an ionic group such as a group or a carboxyl group and / or a nonionic hydrophilic group-containing compound, the hydrophilic group is added to the main chain and / or side chain of the polymer. After introduction, a method of dissolving or dispersing in water; (2) After synthesizing a urethane prepolymer terminated with an isocyanate group having a hydrophilic group introduced into the main chain and / or side chain, as in the method of (1) above. , A method of dispersing in water and causing a chain extension reaction with polyamine and / or water.

  Examples of the ionic hydrophilic group-containing compound used for the production of the self-emulsifying aqueous polyurethane resin include compounds containing an anionic group or a cationic group in the molecule. Of these compounds, anionic group-containing compounds are particularly preferred. Examples of the anion group-containing compound include 1,2-dimethylolethanesulfonic acid, sulfosuccinic acid, 2-aminoethylaminoethanesulfonic acid, 1,3-phenylenediamine-4,6-disulfonic acid, and 2,4-diamino. Sulfonic acid group-containing compounds such as toluene-5-sulfonic acid and salts and derivatives thereof; 2,2-dimethylolpropionic acid, 2,2-dimethylolbutyric acid, 2,2-dimethylolvaleric acid, dioxymaleic acid, 2 , 6-dioxybenzoic acid, 3,4-diaminobenzoic acid and other carboxylic acid group-containing compounds and salts and derivatives thereof. These anionic group-containing compounds may be used alone or in combination of two or more.

  Examples of the nonionic hydrophilic group-containing compound include polyethylene glycol, ethylene oxide-propylene oxide copolymer and monoalkyl ethers of these polyalkylene glycols, which contain at least one active hydrogen group in the polymer. These nonionic hydrophilic group-containing compounds may be used alone or in combination of two or more.

  The content of the hydrophilic group in the self-emulsifying aqueous polyurethane resin is at least 0.5 mass with respect to 100 mass of the solid content of the self-emulsifying aqueous polyurethane resin with respect to the ionic group of the anionic group or cationic group. Parts are required, preferably 1.5 to 20 parts by mass.

  The self-emulsifying aqueous polyurethane resin containing an ionic group (hereinafter sometimes referred to as “ionomer type urethane resin”) may be, for example, any of polyacrylic, polyester, and polyether types. Good. Further, the ionomer type polyurethane resin may be modified with, for example, polyepoxy, polyaziridine or the like.

  The isocyanate curing agent used for the water-based polyurethane adhesive is also preferably a self-emulsifying type. As a manufacturing method of the self-emulsifying type isocyanate curing agent, for example, the above-mentioned water-dispersible polyalkylene glycol is listed as the isocyanate curing agent when the polyurethane resin composition for forming the easy-adhesion layer is described. The method of making it react with such a polyisocyanate compound is mentioned. As the polyisocyanate compound, an aliphatic or cycloaliphatic polyisocyanate compound is preferably used in order to avoid stability of the isocyanate group after water dispersion and yellowing of the adhesive layer. It is preferable to use a polyisocyanate compound having a group. Examples of the water-dispersible polyalkylene glycol include polyethylene glycol, polypropylene glycol, ethylene oxide-propylene oxide copolymer, and the like. In these water-dispersible polyalkylene glycols, the hydroxyl group at one end is etherified or esterified with, for example, an alkyl group such as a methyl group or an acyl group such as an acetyl group, and becomes inert with respect to an isocyanate group. It is preferable to use what has become. These polyalkylene glycols are introduced in such an amount that the obtained isocyanate curing agent can be dispersed in water. Specifically, the amount of polyalkylene glycol introduced is preferably 2 to 50 parts by mass with respect to 100 parts by mass of the polyisocyanate compound as a solid content. The number average molecular weight of the polyalkylene glycol is preferably about 200 to 10,000.

  In addition, the self-emulsifying type isocyanate curing agent imparts water dispersibility to a polyisocyanate compound by introducing a functional group having low reactivity with an isocyanate group such as a carboxylate, a sulfonate, and a quaternary ammonium salt. Can also be manufactured.

  Furthermore, when the self-emulsifying type isocyanate curing agent is dispersed in water, the sum of the carbon number of the fatty acid and the alcohol is 8 or more in order to slow the reaction between the isocyanate group and water, and It may be introduced with a hydrophobic group such as a fatty acid ester having an active hydrogen group capable of reacting. Further, the self-emulsifying type isocyanate curing agent may be one in which the terminal isocyanate group is protected with oxime or lactam in order to prevent the isocyanate group from reacting with water. In this case, by heating, the protecting group is detached from the isocyanate group, and the isocyanate group reacts.

<Isocyanate adhesive>
The isocyanate adhesive means an adhesive mainly composed of a polyisocyanate compound. In addition, “having a polyisocyanate compound as a main component” means that at least 50% by mass or more, more preferably 80% by mass or more, and still more preferably 90% by mass or more of the non-volatile content constituting the adhesive. It means that. Examples of the polyisocyanate compound used in the isocyanate-based adhesive include 1,5-naphthalene diisocyanate, 4,4′-diphenylmethane diisocyanate, 4,4′-diphenyldimethylmethane diisocyanate, tetramethyldiphenylmethane diisocyanate, and 1,3-phenylene. Diisocyanate, 1,4-phenylene diisocyanate, 2-chloro-1,4-phenyl diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, butane-1,4-diisocyanate, hexamethylene diisocyanate, 2, 2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, cyclohexane-1,4-diisocyanate, xylylene diene Socyanate, isophorone diisocyanate, dicyclohexylmethane-4,4′-diisocyanate, 1,3-bis (isocyanate methyl) cyclohexane, methylcyclohexane diisocyanate, 4,4′-diphenyl ether diisocyanate, 4,4′-diphenyl sulfoxide diisocyanate, 4,4 '-Diphenylsulfone diisocyanate, 4,4'-biphenyl diisocyanate, and modified products derived from these polyisocyanate compounds such as dimer, trimer (isocyanurate), polymeric MDI, trimethylolpropane Examples include adducts, biurets, allophanates, and urea-modified products. As the polyisocyanate compound, an aliphatic or cycloaliphatic polyisocyanate compound may be used in order to avoid yellowing of the adhesive layer and, when dispersed in water, for the stability of the isocyanate group. It is preferable to use a polyisocyanate compound having three or more isocyanate groups. Further, the polyisocyanate compound may be a compound in which the terminal isocyanate group is protected with oxime or lactam.

  The isocyanate-based adhesive is usually used in a solvent system or an aqueous system. In the case of a solvent system, it can be used in the form of a solution, for example, using the same solvent as the polyurethane adhesive, and in the case of an aqueous system, for example, in the form of an aqueous solution, an emulsion, or a colloidal dispersion. The polyisocyanate compound used in the water-based isocyanate adhesive can be produced by applying the same method as that for making the isocyanate-based curing agent used in the water-based polyurethane adhesive. Among them, a self-emulsifying type polyisocyanate compound obtained by introducing a water-dispersible polyalkylene glycol is particularly suitable, and the sum of the number of carbon atoms of fatty acid and alcohol is 8 or more, and reacts with an isocyanate group. It is possible to introduce a hydrophobic group such as a fatty acid ester having an active hydrogen group or to protect the terminal isocyanate group with oxime or lactam.

<Reaction catalyst, additive and solid content>
In general, isocyanate groups are very reactive groups and readily react with compounds containing active hydrogen at room temperature. Therefore, it is possible to provide strong adhesion by chemical reaction with an easy adhesion layer containing a polyurethane resin and / or an amino group-containing polymer, a PVA polarizer, or, in some cases, a saponified TAC film. In the polyurethane adhesive and the isocyanate adhesive of the present invention, a reaction catalyst may be used in order to improve the reactivity of the isocyanate group. Although the reaction catalyst is not particularly limited, for example, a tin-based catalyst and an amine-based catalyst are suitable. Specifically, a polyurethane resin composition (two-component polyurethane resin for forming an easy-adhesion layer) is preferable. Examples thereof include tin-based catalysts and amine-based catalysts listed in the description of the composition). These reaction catalysts may be used alone or in combination of two or more. The amount of the reaction catalyst used is, for example, preferably 0.01 to 10 parts by mass, more preferably 0.1 to 5 parts by mass with respect to 100 parts by mass of the isocyanate curing agent.

  A conventionally well-known additive can also be mix | blended with an adhesive agent. Examples of other additives that can be added to the adhesive include coupling agents such as silane coupling agents and titanium coupling agents; adhesive properties such as terpene resins, phenol resins, terpene-phenol resins, rosin resins, and xylene resins. Giving agents; leveling agents; stabilizers such as UV absorbers, antioxidants, heat stabilizers, hydrolysis stabilizers; antifoaming agents; plasticizers; inorganic fillers;

  The solid content of the adhesive is preferably 1 to 50% by mass and more preferably 5 to 40% by mass with respect to the total mass of the adhesive. If the solid content is less than 1% by mass, the adhesion may be insufficient. On the other hand, when the solid content exceeds 50% by mass, the viscosity of the adhesive increases, so that uneven adhesion may occur.

≪Production of polarizing plate≫
In the polarizing plate of the present invention, a thermoplastic resin film containing a lactone ring-containing polymer as a main component is bonded to at least one surface of a polarizer via an easy adhesion layer containing a polyurethane resin and / or an amino group-containing polymer. Manufactured by pasting with an agent.

  In general, the same type of protective film is bonded to both sides of the polarizer, but the polarizing plate of the present invention may be the same type of film, or different types of films. It may be. In any case, a thermoplastic resin film mainly composed of a lactone ring-containing polymer is formed on one surface of the polarizer via an easy-adhesion layer containing a polyurethane resin and / or an amino group-containing polymer. The protective film bonded to the other surface is not particularly limited. Therefore, for example, on one surface of the polarizer, a thermoplastic resin film mainly composed of a lactone ring-containing polymer is bonded with an adhesive via an easy-adhesion layer containing a polyurethane resin and / or an amino group-containing polymer. What is necessary is just to be bonded, and the protective film which consists of TAC may be bonded to the other surface. When pasting a resin film having a relatively high moisture permeability such as a TAC film, an adhesive used in a conventionally known polarizing plate may be used. At this time, if a PVA resin is added to the adhesive, the adhesive strength between the polarizer and the TAC film is improved.

  First, an easy-adhesion layer coating composition containing a polyurethane resin and / or an amino group-containing polymer is applied to one surface of a protective film, and then dried, cured, or dried to form an easy-adhesion layer. Next, the protective film is bonded with an adhesive so that the easy adhesion layer of the protective film faces at least one surface of the polarizer. Hereinafter, a protective film having an easy-adhesion layer formed on the surface may be simply referred to as a “protective film”.

  As a method for bonding the protective film to the polarizer, for example, (1) An adhesive solution is applied to both or one of the polarizer and the protective film, and the polarizer and the protective film are bonded before the coating film is dried. Next, a method of adhering after removing the solvent (so-called wet lamination), and (2) applying an adhesive solution to both or one of the polarizer and the protective film, and then substantially removing the solvent to form a coating film There is a method (so-called dry lamination) in which the polarizer and the protective film are bonded together after being almost dried, and are adhered by pressurization and / or heating. Although the thickness of an adhesive bond layer is not specifically limited, For example, Preferably it is 0.01-5 micrometers, More preferably, it is 0.03-3 micrometers, More preferably, it is 0.05-1 micrometer. In addition, when using the adhesive agent containing a hardening | curing agent, since reaction with a main component and a hardening | curing agent advances by heating during adhesion | attachment and curing, it is not necessary to provide a hardening process separately.

  (1) In the case of wet lamination, for example, considering the thickness of the adhesive layer after bonding, coating properties, etc., the adhesive is used as a solvent so that the solid content concentration is, for example, 1 to 50% by mass. After dissolution, the adhesive solution is applied or dropped onto the polarizer and / or protective film with a Meyer bar, gravure coater, micro gravure coater, etc., and the polarizer with the protective film adhered is, for example, with two rolls The solvent is removed by heating or the like while laminating. Laminate while extruding excess adhesive with a roll, and dry it with hot air to bond.

  A drying temperature becomes like this. Preferably it is 120 degrees C or less, More preferably, it is 50-100 degreeC. The viscosity of the adhesive solution is preferably 10 to 20,000 mPa · s, more preferably 100 to 12,000 mPa · s. If the viscosity is less than 10 mPa · s, the adhesive solution may excessively flow out of the polarizing plate due to pressurization during lamination, and the thickness of the adhesive layer may be reduced. On the contrary, when the viscosity exceeds 20,000 mPa · s, the coatability may be lowered. In wet lamination, when water is used as a solvent, a conventional polarizing plate manufacturing facility that uses a TAC film as a protective film can be effectively used as it is as a protective film bonding facility.

  (2) In the case of dry lamination, for example, in consideration of the thickness of the adhesive layer after coating and coating properties, the adhesive is dissolved in a solvent so as to obtain an appropriate solid content concentration, and then a bar coater or roll coater. Then, it is applied to a polarizer and / or protective film with a gravure coater or the like, and the solvent is removed using means such as passing through a drying furnace. The heating temperature is preferably set within the range of room temperature to 130 ° C. Lamination of the polarizer and the protective film is performed, for example, by using two rolls or the like, and preferably pressing and applying pressure of 98 to 980 kPa. In that case, you may heat a polarizing plate in the range which does not reduce the optical performance of a polarizer, The temperature becomes like this. Preferably it is 120 degrees C or less, More preferably, it is 30-100 degreeC. The viscosity of the adhesive solution is in the same range as in the case of wet lamination. If the viscosity is less than 10 mPa · s, it may take time to remove the solvent, and productivity may decrease. On the contrary, when the viscosity exceeds 20,000 mPa · s, the coating property is lowered. In dry lamination, it is preferable to use an organic solvent as the solvent because the adhesive strength between the polarizer and the protective film is excellent.

  In any bonding method, any known means may be used for laminating the polarizer and the protective film. However, the method using a nip roll is simple and excellent in productivity. As the nip roll, a rubber roll and a metal roll can be combined, or a rubber roll and a rubber roll can be combined. The pressure at the time of lamination is a nip line pressure, preferably 1 to 100 kgf / cm, more preferably 3 to 30 kgf / cm.

  The polarizing plate obtained by the above method is cured, that is, is allowed to stand for a certain period of time and is cured without any problem, thereby improving the adhesive strength between the adhesive layer and each layer, the durability of each layer, and the like. be able to. The curing conditions are preferably normal temperature or warming (for example, about 30 to 60 ° C.) and left for about 5 to 72 hours. Moreover, after bonding a protective film and a polarizer through an adhesive bond layer, you may adjust the thickness of an adhesive bond layer by applying a pressure to this.

  An adhesive layer for adhering to another member such as a liquid crystal cell may be provided on the polarizing plate described above or an optical film in which at least one polarizing plate is laminated. The pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is not particularly limited. For example, an acrylic polymer, silicone polymer, polyester, polyurethane, polyamide, polyether, fluorine-based or rubber-based polymer is used as a base. The pressure-sensitive adhesive can be appropriately selected and used. Among these pressure-sensitive adhesives, acrylic pressure-sensitive adhesives are particularly preferred because they are excellent in optical transparency, exhibit good pressure-sensitive adhesive properties such as moderate wettability, cohesiveness, and adhesion, and are excellent in weather resistance, heat resistance, and the like. .

≪Use of polarizing plate≫
The polarizing plate of the present invention can be applied to any application as long as it uses the polarizing function of the polarizer, but in particular, the adhesive strength between the polarizer and the protective film is high, flex resistance, reworkability, Excellent water resistance, moisture resistance, etc., making it suitable for various electronic equipment components used in harsh environments such as high temperature and humidity, such as LCDs, organic EL elements, light shielding window glass, and polarized glasses. .

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, but may be appropriately modified within a range that can meet the purpose described above and below. It is also possible to implement, and they are all included in the technical scope of the present invention. Hereinafter, for convenience, “parts by mass” may be represented by “parts” and “mass%” may be represented by “wt%”.

  First, the evaluation method of a lactone ring containing polymer, a protective film, and a polarizing plate is demonstrated.

<Polymerization reaction rate, polymer composition analysis>
For the reaction rate during the polymerization reaction and the content of the specific monomer unit in the polymer, the amount of unreacted monomer in the obtained polymerization reaction mixture was measured using a gas chromatograph (GC17A, manufactured by Shimadzu Corporation). It was obtained by measuring using.

<Dynamic TG>
The polymer (or polymer solution or pellet) is once dissolved or diluted in tetrahydrofuran, poured into excess hexane or methanol for reprecipitation, and the taken out precipitate is vacuum dried (1 mmHg (1.33 hPa), 80 ° C. Volatile components and the like were removed by conducting the reaction for 3 hours or more, and the obtained white solid resin was analyzed by the following method (dynamic TG method).
Measuring apparatus: differential type differential thermal balance (Thermo Plus 2 TG-8120 Dynamic TG, manufactured by Rigaku Corporation)
Measurement conditions: Sample amount 5-10 mg
Temperature increase rate: 10 ° C / min
Atmosphere: Nitrogen flow 200 mL / min
Method: Step-like isothermal control method (controlled to a mass reduction rate value of 0.005% / s or less in the range from 60 ° C to 500 ° C)

<Containing ratio of lactone ring structure>
First, based on the amount of mass reduction that occurs when all hydroxyl groups are dealcoholated as methanol from the obtained polymer composition, 300 before the start of decomposition of the polymer from 150 ° C. before the mass reduction starts in dynamic TG measurement. The dealcoholization reaction rate was determined from the mass reduction due to the dealcoholization reaction up to ° C.

That is, in the dynamic TG measurement of the polymer having a lactone ring structure, the mass reduction rate between 150 ° C. and 300 ° C. is measured, and the obtained actual measurement value is defined as the actual mass reduction rate (X). On the other hand, from the composition of the polymer, the mass reduction rate when assuming that all the hydroxyl groups contained in the polymer composition become alcohol and dealcoholate because they are involved in the formation of the lactone ring (that is, 100 in the composition) % Mass reduction rate calculated assuming that the dealcoholization reaction occurred) is defined as the theoretical mass reduction rate (Y). The theoretical mass reduction rate (Y) is more specifically the molar ratio of raw material monomers having a structure (hydroxyl group) involved in the dealcoholization reaction in the polymer, that is, the raw material single amount in the polymer composition. It can be calculated from the body content. These values are calculated for the dealcoholization:
1- (actual mass reduction rate (X) / theoretical mass reduction rate (Y))
Substituting for, the value is obtained and expressed in percentage (%), the dealcoholization reaction rate is obtained. Then, the content (mass ratio) in the polymer composition of the raw material monomer having a structure (hydroxyl group) involved in lactone cyclization, assuming that the predetermined lactone cyclization has been performed by the dealcoholization reaction rate. The content ratio of the lactone ring structure in the polymer can be calculated by multiplying the reaction rate by the dealcoholization reaction rate.

  As an example, the content rate of the lactone ring structure in the pellet obtained by manufacture of the below-mentioned protective film is calculated. When the theoretical mass reduction rate (Y) of this polymer was determined, the molecular weight of methanol was 32, the molecular weight of methyl 2- (hydroxymethyl) acrylate was 116, and methyl 2- (hydroxymethyl) acrylate. Since the content (mass ratio) in the polymer is 20.0% by mass in terms of composition, (32/116) × 20.0≈5.52% by mass. On the other hand, the actual mass reduction rate (X) by dynamic TG measurement was 0.17% by mass. When these values are applied to the above-described dealcoholization calculation formula, 1− (0.17 / 5.52) ≈0.969, and the dealcoholization reaction rate is 96.9%. In the polymer, the content (20.0% by mass) of methyl 2- (hydroxymethyl) acrylate in the polymer is determined as having been subjected to predetermined lactone cyclization corresponding to the dealcoholization reaction rate. Multiplied by the dealcoholization rate (96.9% = 0.969), the content of the lactone ring structure in the polymer is 19.4 (20.0 × 0.969) mass%.

<Weight average molecular weight and number average molecular weight>
The weight average molecular weight and / or number average molecular weight of the polymer was determined by gel conversion using a gel permeation chromatograph (GPC system, manufactured by Tosoh Corporation). Tetrahydrofuran was used as the solvent.

<Melt flow rate>
The melt flow rate was measured at a test temperature of 240 ° C. and a load of 10 kg in accordance with JIS-K6874.

<Thermal analysis of polymer>
The thermal analysis of the polymer was performed using a differential scanning calorimeter (DSC-8230, manufactured by Rigaku Corporation) under the conditions of about 10 mg of sample, a heating rate of 10 ° C./min, and a nitrogen flow of 50 mL / min. In addition, the glass transition temperature (Tg) was calculated | required by the midpoint method based on ASTM-D-3418.

<Optical characteristics>
The in-plane retardation Δnd and thickness direction retardation Rth were calculated from the refractive indices nx, ny, and nz measured using an automatic birefringence measuring apparatus (KOBRA-21ADH, manufactured by Oji Scientific Instruments). The total light transmittance was measured using a turbidimeter (NDH-1001DP, manufactured by Nippon Denshoku Industries Co., Ltd.) in accordance with ASTM-D1003 for a molded product obtained by injection molding.

<Adhesiveness between polarizer and protective film (bending test)>
The obtained polarizing plate was bent up and down with a bending diameter of 3 mm, and the presence or absence of peeling at the interface between the polarizer and the protective film was confirmed. The determination was made according to the following criteria.
○: No peeling at the interface between the polarizer and the protective film ×: There is peeling at the interface between the polarizer and the protective film

<Adhesiveness between polarizer and protective film (rework test)>
One side of the obtained polarizing plate was subjected to adhesive processing and attached to a glass plate to obtain a test sample. The polarizing plate was peeled off from one corner in the diagonal direction at a speed of 1 mm / sec in the direction of 90 degrees, and the peeling position was confirmed. The determination was made according to the following criteria.
○: Peeled at the interface between the adhesive and the glass plate ×: Peeled at the interface between the polarizer and the protective film

<Water resistance>
The obtained polarizing plate was cut into a 25 × 50 mm rectangle and immersed in warm water at 60 ° C. for 4 hours, and then the presence or absence of peeling at the interface between the polarizer and the protective film was confirmed. The determination was made according to the following criteria.
○: No peeling at the interface between the polarizer and the protective film Δ: There is peeling at a part of the interface between the polarizer and the protective film ×: Peeling at the entire interface between the polarizer and the protective film

<Moisture resistance>
The obtained polarizing plate was cut into a rectangle of 25 × 50 mm, put into a constant temperature and humidity machine of 60 ° C./95% RH, taken out after 500 hours, and the state of discoloration and peeling was visually observed. The determination was made according to the following criteria.
◎: No peeling / discoloration ○: No peeling / slight discoloration ×: With peeling / discoloration

  Next, the manufacture example of a protective film, a polarizer, an easily bonding layer coating composition, and an adhesive agent is demonstrated.

<Protective film>
In a 30 L capacity reactor equipped with a stirrer, temperature sensor, cooling pipe, and nitrogen introduction pipe, 8,000 g of methyl methacrylate (MMA) and 2,000 g of methyl 2- (hydroxymethyl) methyl acrylate (MHMA) were added. ) 10,000 g of 4-methyl-2-pentanone (methyl isobutyl ketone, MIBK), 5 g of n-dodecyl mercaptan were charged, and the temperature was raised to 105 ° C. while passing nitrogen, and when the mixture was refluxed, the polymerization initiator At the same time as adding 5.0 g of t-butylperoxyisopropyl carbonate (Kaya-Carbon BIC-7, manufactured by Kayaku Akzo Co., Ltd.) and simultaneously adding a solution of 10.0 g of t-butylperoxyisopropyl carbonate and 230 g of MIBK. While dropping over 4 hours, solution polymerization was conducted at about 105 to 120 ° C. under reflux. Aging was carried out over a period of 4 hours.

  To the obtained polymer solution, 30 g of stearyl phosphate / distearyl phosphate mixture (Phoslex A-18, manufactured by Sakai Chemical Industry Co., Ltd.) was added and cyclized at about 90-120 ° C. for 5 hours under reflux. A condensation reaction was performed. Next, the obtained polymer solution was a vent type screw twin screw extruder having a barrel temperature of 260 ° C., a rotation speed of 100 rpm, a degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg), a rear vent number of 1, and a forevent number of 4. (Φ = 29.75 mm, L / D = 30) is introduced at a processing rate of 2.0 kg / h in terms of resin amount, and is further subjected to cyclization condensation reaction and devolatilization in this extruder and extruded. As a result, transparent pellets of the lactone ring-containing polymer were obtained.

  The obtained lactone ring-containing polymer was measured for dynamic TG, and a mass loss of 0.17% by mass was detected. The lactone ring-containing polymer had a weight average molecular weight of 133,000, a melt flow rate of 6.5 g / 10 min, and a glass transition temperature of 131 ° C.

  The obtained pellets and acrylonitrile-styrene (AS) resin (Toyo AS AS20, manufactured by Toyo Styrene Co., Ltd.) are kneaded and extruded at a mass ratio of 90/10 using a single screw extruder (screw 30 mmφ). Thus, a transparent pellet was obtained. The obtained pellet had a glass transition temperature of 127 ° C.

  This pellet was melt-extruded from a coat hanger type T die having a width of 400 mm using a 50 mmφ single-screw extruder to produce a film having a thickness of 100 μm. This was subjected to a temperature condition of 150 ° C. using a biaxial stretching apparatus. The film was stretched 1.5 times to obtain a stretched film having a thickness of 40 μm. When the optical properties of the stretched film were measured, the total light transmittance was 93%, the in-plane retardation Δnd was 0.8 nm, and the thickness direction retardation Rth was 1.5 nm. As the protective film, this stretched film (hereinafter sometimes referred to as “protective film A”) was used.

  On the other hand, a film obtained by saponifying a commercially available TAC film having a thickness of 80 μm (hereinafter sometimes referred to as “protective film B”) was prepared. When the optical characteristics of the protective film B were measured, the total light transmittance was 92%, the in-plane retardation Δnd was 8.7 nm, and the thickness direction retardation Rth was 45.5 nm.

<Polarizer>
A 75 μm-thick polyvinyl alcohol film was stretched 5 times in a dry manner, immersed in an aqueous 0.5 mass% iodine solution for 60 seconds, and then immersed in an aqueous boric acid solution at 75 ° C. for 250 seconds.
Thereafter, the film was washed with pure water at 25 ° C. for 20 seconds and dried at 60 ° C. to obtain a polarizer having iodine adsorbed and oriented on a polyvinyl alcohol film.

<Easily adhesive layer coating composition>
Easy-adhesion layer coating composition P-1
In a four-necked flask equipped with a thermometer, a stirrer, a cooler, a dropping funnel, and a nitrogen gas introduction tube, 200 parts of toluene and 100 parts of isopropyl alcohol as solvents, 80 parts of butyl methacrylate and 25 parts of butyl acrylate as monomers Part, 75 parts of methyl methacrylate and 20 parts of methacrylic acid were added and the temperature was raised to 85 ° C. with stirring while introducing nitrogen gas.

  As a polymerization initiator, a mixture of 0.005 part of 2,2′-sobisisobutyronitrile (trade name ABN-R, manufactured by Nippon Hydrazine Kogyo Co., Ltd.) and 10 parts of toluene is added in portions over 7 hours. did. Further, aging was performed at 85 ° C. for 3 hours, and then cooled to room temperature to obtain a polymer having a weight average molecular weight (Mw) of 90,000.

  Next, after raising the temperature of the flask to 40 ° C., 20 parts of ethyleneimine was added dropwise over 1 hour, and the temperature was further maintained for 1 hour, then the internal temperature was raised to 75 ° C. and aged for 4 hours. Went. A distillation apparatus was set in a four-necked flask and heated under reduced pressure to cause both isopropyl alcohol and unreacted ethyleneimine to flow out of the system to completely remove the remaining ethyleneimine. Finally, the non-volatile content was adjusted to 10 wt% with toluene to obtain an easy-adhesion layer coating composition P-1 containing an ethyleneimine-modified acrylic resin (polymer having an amino group in the side chain).

Easy-adhesion layer coating composition P-2
A four-necked flask equipped with a thermometer, a heating device, a stirrer, a reflux condenser, a nitrogen gas introducing device, and a dropping funnel was charged with 115 parts of xylene and 30 parts of butyl acetate, and heated and stirred while introducing nitrogen gas, When the internal temperature reached 100 ° C., 15 parts of 2-hydroxyethyl methacrylate, 50 parts of methyl methacrylate, 33 parts of butyl methacrylate, 2 parts of methacrylic acid, 1,1-bis (t-hexyl par A mixture of 0.26 part of (oxy) cyclohexane (manufactured by NOF Corporation) was added dropwise over 2 hours with a dropping funnel at a constant temperature of 100 ° C. After completion of the dropwise addition, the mixture was kept at 100 ° C. for 2 hours, and then a mixture of 0.05 part of 1,1-bis (t-hexylperoxy) cyclohexane and 5 parts of xylene was dropwise added and kept for another 2 hours. Thereafter, the internal temperature was raised to 110 ° C. and held for 2 hours to complete the reaction, and the polymerization solution was cooled to room temperature to obtain a polymerization solution having a nonvolatile content of 40%. The weight average molecular weight (Mw) of the polymer was 27,000, the number average molecular weight (Mn) was 17,000, and the hydroxyl value was 70 mgKOH / g · solid.

  10 parts of the resulting acrylic polyol polymerization liquid, 0.9 part of hexamethylene diisocyanate (HDI) -based modified polyisocyanate (active ingredient 100%, biuret body) as an isocyanate curing agent, weighed and diluted with 38 parts of toluene, An easy-adhesion layer coating composition P-2 having a nonvolatile content of 10% was obtained. This easy-adhesion layer coating composition P-2 is an example of a two-component polyurethane resin composition containing a polyacryl polyol and an isocyanate curing agent in a solvent.

Easy-adhesion layer coating composition P-3
194.2 parts of dimethyl terephthalate, 124 parts of ethylene glycol, 208.3 parts of neopentyl glycol, 0.14 part of antimony trioxide and 0.2 part of zinc acetate were charged into a reactor under a nitrogen stream at 160 to 220 ° C. A transesterification reaction was performed. After flowing out a predetermined amount of methanol, 202.3 parts of sebacic acid is added, esterification is performed at 220 to 230 ° C., the pressure is gradually reduced, and condensation is performed at 230 to 260 ° C. for 30 minutes, and then 0.1 to 0.2 mmHg. A polycondensation reaction was performed at 270 to 275 ° C. for 2 hours. A polyester glycol having a number average molecular weight of about 10,000 was obtained. The obtained polyester glycol was dissolved in a mixed solvent of toluene / methyl ethyl ketone (mass ratio 1/1) to obtain a solution (P-3-A) having a nonvolatile content of 50%.

  A mixed liquid of 174.2 parts of tolylene diisocyanate (2,4-isomer / 2,6-isomer = 80/20), 44.7 parts of trimethylolpropane, and 73.0 parts of ethyl acetate was mixed at 65 ° C. By reacting for a period of time, a polyurethane isocyanate solution (P-3-B) having a non-volatile content of 75%, an NCO group content of 14.4%, and a number average molecular weight of 657 was obtained.

  100 parts of the obtained acrylic polyol polymerization liquid (P-3-A) and 10 parts of polyurethane isocyanate solution (P-3-B) were diluted with 465 parts of toluene, and an easy-adhesion layer coating composition having a nonvolatile content of 10%. P-3 was obtained. This easy-adhesion layer coating composition P-3 is an example of a two-component polyurethane resin composition containing a polyester polyol and an isocyanate curing agent in a solvent.

Easy-adhesion layer coating composition P-4
A reactor equipped with a thermometer, a stirrer and a partial reflux condenser was charged with 932 parts of dimethyl isophthalate, 488 parts of ethylene glycol, 400 parts of neopentyl glycol and a catalyst, and subjected to transesterification at 140-210 ° C. for 4 hours. went. Subsequently, the reaction system was depressurized to 1,333 Pa (10 mmHg) over 90 minutes, and a polycondensation reaction was further performed at 230 ° C. and 133 Pa (1 mmHg) or less for 30 minutes. The number average molecular weight of the obtained polyester diol was 2,400. Moreover, as a result of analyzing the obtained polyester diol by NMR, the composition was 100 mol% of isophthalic acid, 50 mol% of ethylene glycol, and 50 mol% of neopentyl glycol.

  Next, a reactor equipped with a thermometer and a stirrer was charged with 445 parts of toluene, 445 parts of methyl ethyl ketone, 500 parts of the above polyester diol, and 30 parts of neopentyl glycol, dissolved at 60 ° C., and 4,4-diphenylmethane diisocyanate 121 there. And 0.3 part of dibutyltin laurate were charged as part and catalyst. The reaction was carried out for 10 hours while adjusting the temperature to 80 ° C. Thereafter, 330 parts of toluene and 330 parts of methyl ethyl ketone were charged and stirred for 1 hour to obtain a polyurethane resin. The number average molecular weight of the obtained polyurethane resin was 38,000. Furthermore, it diluted to 10 wt% of non volatile matters with the mixed solvent of toluene / methyl ethyl ketone (mass ratio 1/1), and the easily bonding layer coating composition P-4 was obtained. This easy-adhesion layer coating composition P-4 is an example of a one-component polyurethane resin composition containing a polyester-based polyurethane resin in a solvent.

Easy-adhesion layer coating composition P-5
In a reactor equipped with a thermometer, nitrogen gas inlet tube, and stirrer, 38 parts of tolylene diisocyanate (Desmodur T-80, Nippon Polyurethane Industry Co., Ltd .; NCO group content 48.1%) and castor oil (trade name) By reacting 62 parts of LAV, manufactured by Ito Oil Co., Ltd .; average molecular weight 1,050, hydroxyl value 160) in nitrogen gas at 75 ° C. for 4 hours, an NCO terminal having an NCO group content of 10.8% is obtained. A urethane prepolymer was obtained. Furthermore, it diluted to 10 wt% of non volatile matters with the mixed solvent of toluene / ethyl acetate (mass ratio 4/1), and the easily bonding layer coating composition P-5 was obtained. This easy-adhesion layer coating composition P-5 is an example of a one-component moisture-curable polyurethane resin composition.

<Adhesive>
Adhesive 1
First, 300 parts of hexamethylene diisocyanate and 2.4 parts of 1,3-butanediol were charged into a reactor equipped with a thermometer, a stirrer, a nitrogen seal tube, and a cooling tube, and the inside of the reactor was purged with nitrogen and stirred. Then, the reaction temperature was heated to 80 ° C., and the reaction was performed at the same temperature for 2 hours. Next, 0.06 part of potassium caprate as a catalyst and 0.3 part of phenol as a cocatalyst were added, and an isocyanuration reaction was performed at 60 ° C. for 4.5 hours. 0.042 parts of phosphoric acid was added to this reaction solution as a terminator, and after stirring at the reaction temperature for 1 hour, free hexamethylene diisocyanate was removed by thin-film distillation at 120 ° C. and 1.33 Pa (0.01 mmHg). The obtained polyisocyanate compound had an NCO group content of 21.1%, a viscosity of 2,200 cP / 25 ° C., and a free hexamethylene diisocyanate content of 0.4%.

  Using 100 parts of the obtained polyisocyanate compound, 12 parts of polyoxyethylene methyl ether (trade name methoxy PEG # 400, manufactured by Toho Chiba Kogyo Co., Ltd .; hydroxyl value 140), methyl ricinoleate (trade name CO-FA) 4 parts of methyl ester, manufactured by Ito Oil Co., Ltd .; hydroxyl value 160) were added, the temperature was raised, and the reaction was carried out for 3 hours while maintaining at 75 ° C. -Light yellow and transparent self-emulsification type polyisocyanate (1-1) of s / 25 degreeC was obtained. 20 parts of the obtained self-emulsifying polyisocyanate (1-1) and 0.2 part of dibutyltin laurate were mixed and dispersed in 80 parts of deionized water to obtain an adhesive 1 having a nonvolatile content of 20%. This adhesive 1 is an example of an isocyanate-based adhesive containing a self-emulsifying polyisocyanate.

Adhesive 2
While introducing nitrogen gas in a reactor equipped with a thermometer, a nitrogen gas inlet tube, and a stirrer, while heating and stirring 367.2 parts of 1,4-butanediol, 166 parts of isophthalic acid, and 0.05 part of dibutyltin oxide The mixture was melted and subjected to a condensation reaction at 200 ° C. for 8 hours until the acid value became 1.1. After cooling to 120 ° C., 584 parts of adipic acid and 268 parts of 2,2-dimethylolpropionic acid are added, the temperature is raised again to 170 ° C., and the reaction is carried out at this temperature for 23 hours. .5 polyester polyol was obtained. 55 parts of the obtained polyester was dehydrated at 100 ° C. under reduced pressure, then cooled to 60 ° C., 6.58 parts of 1,4-butanediol were added, and the mixture was sufficiently stirred and mixed. 17 parts were added, heated at 100 ° C., and reacted at this temperature for 4.5 hours to obtain an NCO-terminated urethane prepolymer. After completion of the reaction, the mixture was cooled to 40 ° C. and diluted by adding 96.75 parts of acetone to obtain a prepolymer solution. The prepolymer solution was gradually poured into an aqueous amine solution obtained by dissolving 7.04 parts of piperazine and 10.19 parts of triethylamine in advance in 245.19 parts of water, and chain extension and neutralization were simultaneously performed. After removing acetone from this reaction product at 50 ° C. under reduced pressure, water was added to obtain an aqueous dispersion of a polyester ionomer type urethane resin having a nonvolatile content of 30%, a viscosity of 60 mPa · s / 25 ° C., and a pH of 7.1. Obtained. 20 parts of an aqueous dispersion of the obtained polyester ionomer type urethane resin and 1.2 parts of self-emulsifying polyisocyanate (1-1) are dispersed in 14.8 parts of deionized water to obtain an adhesive having a nonvolatile content of 20%. 2 was obtained. The adhesive 2 is an example of a polyurethane adhesive containing a polyester ionomer type urethane resin.

Adhesive 3
Copolyester polyol (number average molecular weight 2,000) of terephthalic acid / isophthalic acid / adipic acid / ethylene glycol / neopentyl glycol (molar ratio 30/30/40/50/50) by the same method as adhesive 2 , Hydroxyl group value 93.0, acid value 0.2) 200 parts, 2,2-dimethylolpropionic acid 13.41 parts, hexanemethylene diisocyanate 33.64 parts were reacted in methyl ethyl ketone and urethanized, and then aqueous ammonia. To obtain a transparent colloidal aqueous dispersion having a nonvolatile content of 20%. Subsequently, 100 parts of the transparent colloidal aqueous dispersion was charged into a reactor equipped with a thermometer and a stirrer, and 1.81 parts of Epicron 850 (Dainippon Ink Chemical Co., Ltd.) was added while stirring. The reaction was carried out at 60 ° C. for 12 hours to obtain an aqueous dispersion of a polyester ionomer type urethane resin modified with polyepoxy. The resulting polyepoxy-modified polyester ionomer-type urethane resin and self-emulsifying polyisocyanate (1-1) were mixed and dispersed in deionized water so that the solid content ratio was 100/20, and the non-volatile content was 20 % Adhesive 3 was obtained. This adhesive 3 is an example of a polyurethane-based adhesive containing a (epoxy-modified) polyester-based ionomer-type urethane resin.

Adhesive 4
A 7.5 wt% aqueous solution of polyvinyl alcohol (Kuraray Poval PVA-110, manufactured by Kuraray Co., Ltd.) was used as the adhesive 4. This adhesive 4 is an example of a PVA adhesive.

  Next, a production example of a polarizing plate and its evaluation will be described.

Example 1
Formation of easy-adhesion layer The easy-adhesion layer coating composition P-1 is applied to one side of the protective film A that adheres to the polarizer with a bar coater # 2, and the solvent is removed by placing it in a 100 ° C hot air dryer. The composition was dried. The thickness of the easy-adhesion layer after drying was 300 nm.

Preparation of polarizing plate Wet the adhesive 1 on the easy-adhesive layer side of the protective film A and one side of the protective film B, wet the polarizer while extruding excess adhesive with a pressure roller so that the polarizer is sandwiched between these protective films. Bonded by lamination. The laminated film bonded in this manner was dried in a hot air drier at 60 ° C. for 10 minutes. Subsequently, it dried and hardened for 15 hours in 50 degreeC oven, and the polarizing plate was produced. The thickness of the adhesive layer after drying was 50 nm. The obtained polarizing plate was evaluated for adhesiveness (bending test, rework test), water resistance, and moisture resistance. The results are shown in Table 1.

<< Examples 2 to 14 and Comparative Examples 1 to 6 >>
Instead of easy-adhesion layer coating composition P-1 and adhesive 1, in some cases, the easy-adhesion layer coating composition and adhesive shown in Table 1 were used, and in some cases, an adhesive was applied. Before, the polarizing plate of Examples 2-14 and Comparative Examples 1-6 was manufactured like Example 1 except having performed the corona discharge process to the easily bonding layer surface side of the protective film A previously. In addition, about the protective film A which apply | coated the easily bonding layer coating composition P-5, the polarizing plate was manufactured using what was left to stand at 23 degreeC for 24 hours after drying. The obtained polarizing plate was evaluated for adhesiveness (bending test, rework test), water resistance, and moisture resistance. The results are shown in Table 1.

<< Examples 15 to 24 >>
In some cases, instead of the easy-adhesion layer coating composition P-1 and the adhesive 1, the easy-adhesion layer coating composition and the adhesive shown in Table 1 were used, and the easy-adhesion layer was formed on both sides of the polarizer. A polarizing plate was produced in the same manner as in Example 1 except that the protective film A formed with was bonded. In addition, about the protective film A which apply | coated the easily bonding layer coating composition P-5, the polarizing plate was manufactured using what was left to stand at 23 degreeC for 24 hours after drying. The obtained polarizing plate was evaluated for adhesiveness (bending test, rework test), water resistance, and moisture resistance. The results are shown in Table 1.

<< Comparative Example 7 >>
Other than using the easy-adhesion layer coating composition and the adhesive shown in Table 1 in place of the easy-adhesion layer coating composition P-1 and the adhesive 1, and bonding the protective film B to both sides of the polarizer Produced a polarizing plate in the same manner as in Example 1. The obtained polarizing plate was evaluated for adhesiveness (bending test, rework test), water resistance, and moisture resistance. The results are shown in Table 1.

  As can be seen from Table 1, the polarizing plates of Examples 1 to 14 have a thermoplastic resin film containing a lactone ring-containing polymer as a main component as a protective film on one surface of the polarizer. A film obtained by saponifying a TAC film is bonded to the other surface of the TAC film with an adhesive, but a polyurethane resin or an amino group-containing polymer is easily contained on the surface facing the polarizer of the protective film. Since the adhesive layer was formed, it exhibited excellent bending resistance, reworkability, water resistance, and moisture resistance. Moreover, although the polarizing plate of Examples 15-24 has bonded the thermoplastic resin film which has a lactone ring containing polymer as a main component on both surfaces of a polarizer as a protective film with an adhesive agent, the said protection is also carried out. Since an easy-adhesion layer containing a polyurethane resin or an amino group-containing polymer was formed on the surface facing the polarizer of the film, the film exhibited excellent bending resistance, reworkability, water resistance, and moisture resistance.

On the other hand, although the protective film is the same as that of Examples 1-14 in the polarizing plate of Comparative Examples 1-4, since the easily bonding layer is not formed in the surface facing the polarizer of the said protective film, it is a corona. Regardless of the presence or absence of the discharge treatment, the water resistance was slightly inferior, and the bending resistance, reworkability, and moisture resistance were very inferior. Moreover, although the protective film is the same as that of Examples 1-14 in the polarizing plate of Comparative Examples 5-6, since the easily bonding layer is not formed in the surface facing the polarizer of the said protective film, it is a corona discharge process. Regardless of the presence or absence, all of bending resistance, reworkability, water resistance and moisture resistance were very inferior. Furthermore, in the polarizing plate of Comparative Example 7, a film obtained by saponifying a TAC film as a protective film is bonded to both surfaces of a polarizer with an adhesive, but the used adhesive is a PVA adhesive. Therefore, although it showed excellent bending resistance and reworkability , the water resistance and moisture resistance were very inferior. In particular, in the polarizing plates of Comparative Examples 5 to 7, the polarizer was dissolved in the water resistance test.

  Thus, when manufacturing a polarizing plate by bonding a thermoplastic resin film mainly composed of a lactone ring-containing polymer as a protective film on at least one surface of the polarizer with an adhesive, the polarizer is opposed to the polarizer of the protective film. If an easy-adhesion layer containing a polyurethane resin and / or amino group-containing polymer is formed on the surface, the adhesive strength between the polarizer and the protective film is high, and excellent bending resistance, reworkability, water resistance, and moisture resistance It can be seen that a polarizing plate having the above can be obtained.

  The polarizing plate of the present invention has high adhesive strength between the polarizer and the protective film in addition to excellent optical properties, and has excellent bending resistance, reworkability, water resistance, moisture resistance, etc. It can be suitably used for LCDs that are components of electronic devices used in harsh environments such as high humidity. Therefore, for example, the durability of an electronic device used outdoors can be enhanced, which greatly contributes to the expansion of the field of using a polarizing plate.

Claims (5)

A polarizing plate in which a thermoplastic resin film containing a lactone ring-containing polymer as a main component is bonded to at least one surface of a polarizer with an adhesive, the surface of the thermoplastic resin film facing the polarizer , An easily adhesive layer containing a polyurethane resin and / or an amino group-containing polymer is formed,
Of the resins constituting the thermoplastic resin film, 70% by mass or more is a lactone ring-containing polymer, and 30% by mass or less is another polymer.
The lactone ring-containing polymer has the following formula (1):
[In the formula (1), R ¹ , R ² and R ³ each independently represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms; the organic residue contains an oxygen atom It is good]
The lactone ring structure represented in possess in content of 5 to 90 wt%,
The polarizing plate characterized in that the thermoplastic resin film is a stretched film .   The polarizing plate according to claim 1, wherein the other polymer is a styrene polymer. The polarizing plate according to claim 1 or 2, wherein in the formula (1), R ¹ is a hydrogen atom, and R ² and R ³ are methyl groups. The polarized light according to claim 1, wherein the thermoplastic resin film is bonded to one surface of a polarizer, and a protective film made of triacetylcellulose is bonded to the other surface with an adhesive. Board. The polarizing plate according to claim 1 , wherein the adhesive for bonding the thermoplastic resin film containing the lactone ring-containing polymer as a main component is a polyurethane adhesive and / or an isocyanate adhesive. .