JP2008179677A - Transparent electroconductive film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transparent electroconductive film having both of durability and low birefringence, and suitably usable for a touch panel. <P>SOLUTION: The transparent electroconductive film has a transparent electroconductive layer at least on one surface of a base material film consisting essentially of an acrylic resin having a ring structure in the main chain and ≥120°C glass transition temperature. The acrylic resin having ≥120°C glass transition temperature is preferably the one comprising a lactone ring-containing polymer as a main component. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a transparent conductive film.

  In recent years, a liquid crystal display element has attracted attention as an image display element, and an input device in which a transparent touch panel is mounted on the liquid crystal display element is used for an information terminal or the like. Here, as a substrate of the touch panel, a composite oxide of indium and tin (hereinafter sometimes simply referred to as “ITO”) is formed on a polyethylene terephthalate (hereinafter sometimes simply referred to as “PET”) film. A transparent conductive film provided with a transparent conductive film made of a metal oxide such as is used.

  With the recent improvement in display quality in the field of liquid crystal display elements, there is an increasing demand for the quality of touch panels combined with display elements. In particular, a decrease in contrast due to the touch panel mounting or a decrease in display quality due to reflection of external light is a serious problem because the display quality is greatly deteriorated. In particular, the PET film is a polymer film that is crystalline and has a large birefringence, so that there is a problem that the display quality of the liquid crystal is greatly impaired.

Therefore, instead of the PET film, a transparent conductive film is produced using a film having a controlled birefringence made of an amorphous polymer such as polycarbonate (hereinafter, sometimes simply referred to as “PC”). Attempts have been made (see, for example, Patent Document 1).
JP-A-8-290515

  However, since the transparent conductive film using PC has poor durability as compared with the conventional transparent conductive film using PET, linearity or contact resistance is obtained when a touch panel is manufactured and a sliding writing test is performed. There was a case where the quality deteriorated greatly. On the other hand, an acrylic resin typified by polymethyl methacrylate (PMMA) has characteristics such as transparency and low refractive index. However, since heat resistance is low, when forming a conductive film by sputtering, Or when providing other coating layers, there existed a problem that transparency and planarity deteriorated.

  This invention is made | formed in view of the said problem, The objective is to provide durability and low birefringence, and to provide the transparent conductive film which can be used suitably as a touch panel.

  As a result of intensive studies by the present inventors paying attention to the above problems, a base film is a resin film mainly composed of an acrylic resin having a ring structure in the main chain and a glass transition temperature of 120 ° C. or higher. The inventors have found that a transparent conductive film having a birefringence suppressed to a low level can be obtained by providing a transparent conductive layer on the surface thereof, thereby completing the present invention.

  That is, the transparent conductive film of the present invention has a transparent conductive layer on at least one side of a base film mainly composed of an acrylic resin having a ring structure in the main chain and a glass transition temperature of 120 ° C. or higher. It has a gist.

  Among the acrylic resins having a glass transition temperature of 120 ° C. or higher, a resin film mainly composed of a polymer having a lactone ring structure in the main chain has high optical isotropy and a very small retardation. By using this resin film as a base film, a transparent conductive film having more excellent optical properties can be obtained, which is preferable.

  In addition, a resin (base material) film containing a lactone ring structure-containing polymer as a main component has not only high optical isotropy (low retardation and low birefringence), but also excellent transparency and heat resistance. Is. Furthermore, since the lactone ring contained in the base film has high polarity, intermolecular force works between the transparent conductive layer provided on the base film surface and the base film, and exhibits excellent adhesion. . Therefore, the transparent conductive film of the present invention has both low birefringence and excellent durability.

The transparent conductive film of the present invention preferably has a visible light transmittance of 80% or more, a photoelastic coefficient of 10 ⁻¹⁰ m ² / N or less, and a retardation of 0 to 100 nm. The transparent conductive layer according to the present invention is preferably made of indium-tin oxide.

  In the transparent conductive film of the present invention, examples of the ring structure in the main chain include a lactone ring, an N-substituted maleimide ring, a maleic anhydride ring, and an N-substituted methacrylimide ring. It is preferable to have. The lactone ring-containing polymer preferably has a lactone ring structure represented by 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 is hydrogen, oxygen, nitrogen, sulfur, phosphorus And may contain halogen atoms]

  From the viewpoint of strength, the base film is preferably stretched.

  The touch panel provided with the transparent conductive film is a recommended embodiment of the present invention.

  The transparent conductive film of the present invention has not only excellent transparency and heat resistance, but also durability and low birefringence. Therefore, the transparent conductive film of the present invention is useful as a touch panel mounted on a display device such as a liquid crystal display or a plasma display that requires durability and high visual characteristics during use.

  Hereinafter, the present invention will be described in detail. However, the scope of the present invention is not limited to these descriptions, and modifications other than the following examples can be made as appropriate without departing from the spirit of the present invention.

  The transparent conductive film of the present invention is characterized in that it has a transparent conductive layer on at least one side of a base film mainly composed of an acrylic resin having a cyclic structure in the main chain and a glass transition temperature of 120 ° C. or higher. It is what has.

  Examples of the ring structure include a lactone ring, an N-substituted maleimide ring, a maleic anhydride ring, and an N-substituted methacrylimide ring. Among these, a ring having a lactone ring is particularly preferable. This is because those having a polymer having a lactone ring structure in the main chain as a main component have high optical isotropy (low retardation and low refraction) in addition to excellent transparency and heat resistance. Therefore, first, the lactone ring-containing polymer that is the main component of the base film according to the present invention will be described.

[Lactone ring-containing polymer]
The base film according to the transparent conductive film of the present invention is a thermoplastic resin film containing a lactone ring-containing polymer as a main component. The lactone ring-containing polymer that is the main component of the base 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 is hydrogen, oxygen, nitrogen, sulfur, phosphorus And may contain halogen atoms]
It preferably has a lactone ring structure represented by

  In the present specification, the “organic residue” is a group which may have a carbon atom and each atom of hydrogen, oxygen, nitrogen, sulfur, phosphorus and halogen via a covalent bond to the carbon atom. . In addition, as said C1-C20 organic residue, C1-C20, such as a methyl group, an ethyl group, a propyl group, an isopropyl group, n-butyl group, an isobutyl group, t-butyl group, a cyclohexyl group, etc. Examples include alkyl groups, aryl groups such as phenyl groups, and aralkyl groups such as benzyl groups.

  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. In addition, since the lactone ring structure gives a positive retardation to the polymer, when the content ratio of the lactone ring structure is large, the retardation of the obtained polymer tends to increase. Even if other structural units (which give a negative retardation) are copolymerized or blended, it may be difficult to adjust the retardation in the plane direction. The content ratio of the lactone ring structure is determined by the dealcoholization reaction rate calculated from the mass reduction by dynamic TG measurement (150 to 300 ° C.) of NMR and (co) polymer having a lactone ring structure, and the raw material used alone. It is calculated | required from the value with the molar ratio of the raw material monomer which has a hydroxyl group in a monomer.

  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, (meth) acrylic acid ester, hydroxy as described later as a method for producing a lactone ring-containing polymer. Group-containing monomer, unsaturated carboxylic acid, 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 —C (O) —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 (similar to the above formula (1)).

A polymer structural unit (repeating structural unit) formed by polymerizing at least one monomer selected from the group consisting of monomers represented by Although the lactone ring structure contributes to the improvement of the heat resistance of the resulting polymer, when it exists excessively, the positive phase difference derived from the lactone ring structure becomes large. Therefore, in order to adjust the content of the lactone ring structure, it is preferable to employ a monomer that can give the polymer a structure other than the lactone ring structure or a monomer that can give a negative phase difference.

  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 20 to 90% by mass, still more preferably 40 to 90% by mass, and particularly preferably 50 to 90% by mass, by polymerizing the hydroxy group-containing monomer. In the case of the polymer structural unit to be formed (repeating structural unit), it is preferably 0 to 30% by mass, more preferably 0 to 20% by mass, further preferably 0 to 15% by mass, and particularly preferably 0 to 10% by mass. is there. 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, after the polymer (a) having a hydroxy group and an ester group in the molecular chain is obtained by a polymerization step, the obtained heavy polymer is obtained. It can be obtained by carrying out a lactone cyclization condensation step for introducing a lactone ring structure into the polymer by heat-treating the compound (a).

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

[Wherein R ⁷ and R ⁸ each independently represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms (similar to the above formula (1))]
A polymer having a hydroxy group and an ester group in the molecular chain can be obtained by performing a polymerization reaction of a monomer component containing the monomer represented by

  Examples of the monomer represented by the above formula (3) include methyl 2- (hydroxymethyl) acrylate, ethyl 2- (hydroxymethyl) acrylate, isopropyl 2- (hydroxymethyl) acrylate, 2- ( Hydroxymethyl) n-butyl acrylate, 2- (hydroxymethyl) acrylate t-butyl and the like. The monomer represented by the general formula (3) 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 obtained polymer may have insufficient heat resistance, solvent resistance and surface hardness. On the contrary, when the content ratio of the monomer represented by the above formula (3) exceeds 90% by mass, gelation occurs in the polymerization step or the lactone cyclization condensation step, and the molding processability of the obtained polymer is low. 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, and examples thereof include (meth) acrylic acid esters, hydroxy group-containing monomers, unsaturated carboxylic acids, 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 —C (O) —O—R ⁶ group is represented, Ac represents an acetyl group, R ⁵ and R ⁶ represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms (similar to the above formula (1)). ]
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 hydroxy group-containing monomer is not particularly limited as long as it is a hydroxy group-containing monomer other than the monomer represented by the above formula (3). For example, α-hydroxymethylstyrene, α -2- (hydroxyalkyl) acrylic acid ester such as hydroxyethylstyrene and methyl 2- (hydroxyethyl) acrylate; 2- (hydroxyalkyl) acrylic acid such as 2- (hydroxyethyl) acrylic acid; and the like. These hydroxy group-containing monomers may be used alone or in combination of two or more.

  When using a hydroxy group-containing monomer 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 0-30 mass%, More preferably, it is 0-20 mass%, More preferably, it is 0-15 mass%, Most preferably, it is 0-10 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 the unsaturated carboxylic acid is used, the content of the unsaturated carboxylic acid in the monomer component to be subjected to the polymerization step is preferably 0 to 30% by mass, more preferably, in order to sufficiently exhibit the effects of the present invention. It is 0-20 mass%, More preferably, it is 0-15 mass%, Most preferably, it is 0-10 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. In particular, in the above formula (2), a monomer in which X is an aryl group is a structural unit that gives a negative phase difference to the polymer. Specifically, styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene, 2-methyl-4-chlorostyrene, 2,4,6 -Trimethylstyrene, α-methylstyrene, cis-β-methylstyrene, trans-β-methylstyrene, 4-methyl-α-methylstyrene, 4-fluoro-α-methylstyrene, 4-chloro-α-methylstyrene, 4-Bromo-α-methylstyrene, 4-t-butylstyrene, 2-fluorostyrene, 3-fluorostyrene, 4-fluorostyrene, 2,4-difluorostyrene, 2,3,4,5,6-pentafluoro Styrene, 2-chlorostyrene, 3-chlorostyrene, 4-chlorostyrene, 2,4-dichlorostyrene, 2,6-dichloro Examples include styrene, octachlorostyrene, 2-bromostyrene, 3-bromostyrene, 4-bromostyrene, 2,4-dibromostyrene, α-bromostyrene, β-bromostyrene, 2-hydroxystyrene, 4-hydroxystyrene, and the like. It is done. These monomers may be used alone or in combination of two or more. Among these monomers, styrene and α-methylstyrene are particularly preferable because copolymerization is easy.

  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%. When the monomer represented by the formula (2) gives a negative retardation to the polymer, if the content of the monomer is too small, the retardation in the plane direction derived from the lactone ring structure On the other hand, if the amount is too large, the negative phase difference becomes too large, and the lactone ring structure that gives a positive phase difference may not cancel the phase difference. However, even if the monomer represented by the above formula (2) is not used, the thermoplastic resin composition at the time of film formation described later comprises a monomer component selected from the above formula (2) (co). The phase difference can also be adjusted by blending the polymers.

  As a form of the polymerization reaction for polymerizing the monomer component to obtain a polymer having a hydroxy group and an ester group in the molecular chain, a polymerization form using a solvent is preferable, and solution polymerization is particularly preferable. .

  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 the like And ether solvents. These solvents may be used alone or in combination of two or more. In addition, 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, it is preferable to use a solvent with a boiling point of 50-200 degreeC.

  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 the monomers used and the 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, 20 mass % Or more.

  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 of the hydroxy 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 hydroxy 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. 5,000, more preferably 5,000 to 1,000,000, still more preferably 10,000 to 500,000, and particularly preferably 50,000 to 500,000. 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 hydroxy 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. The alcohol is by-produced by the cyclized condensation. High heat resistance is imparted by forming a lactone ring structure in the main chain of the polymer (in the main skeleton of the polymer). 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 (similar to the above formula (1)); , Oxygen, nitrogen, sulfur, phosphorus and halogen atoms may be contained]
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.

  In carrying out the cyclization condensation reaction, it is preferable to use an organic phosphorus compound as a catalyst. By using an organophosphorus compound as a catalyst, the cyclization condensation reaction rate can be improved, and coloring of the resulting lactone ring-containing polymer can be greatly reduced. Moreover, when an organophosphorus compound is used as a catalyst, since the molecular weight fall which can occur when using the below-mentioned devolatilization process is suppressed, the outstanding mechanical strength of a lactone ring containing polymer is securable.

  Examples of the organic phosphorus compound used as a catalyst in the cyclocondensation reaction include alkyl (aryl) phosphonous acids such as methylphosphonous acid, ethylphosphonous acid, and phenylphosphonous acid (however, these are tautomers) Which may be an alkyl (aryl) phosphinic acid which is an active substance) and monoesters or diesters thereof; dialkyl (such as dimethylphosphinic acid, diethylphosphinic acid, diphenylphosphinic acid, phenylmethylphosphinic acid, phenylethylphosphinic acid) Aryl) phosphinic acids and their esters; alkyl (aryl) phosphonic acids such as methylphosphonic acid, ethylphosphonic acid, trifluoromethylphosphonic acid, phenylphosphonic acid and their monoesters or diesters; methylphosphite Acids, alkyl (aryl) phosphinic acids such as ethylphosphinic acid, phenylphosphinic acid and their esters; methyl phosphite, ethyl phosphite, phenyl phosphite, dimethyl phosphite, diethyl phosphite, Phosphorous acid monoester, diester or triester such as diphenyl phosphite, trimethyl phosphite, triethyl phosphite, triphenyl phosphite; methyl phosphate, ethyl phosphate, 2-ethylhexyl phosphate, octyl phosphate , Isodecyl phosphate, lauryl phosphate, stearyl phosphate, isostearyl phosphate, phenyl phosphate, dimethyl phosphate, diethyl phosphate, di-2-ethylhexyl phosphate, octyl phosphate, diisodecyl phosphate, dilauryl phosphate, Distearyl phosphate, diisostearyl phosphate, diphosphate phosphate Phosphoric monoesters, diesters or triesters such as phenyl, trimethyl phosphate, triethyl phosphate, triisodecyl phosphate, trilauryl phosphate, tristearyl phosphate, triisostearyl phosphate, triphenyl phosphate; methylphosphine, ethylphosphine , Phenylphosphine, dimethylphosphine, diethylphosphine, diphenylphosphine, trimethylphosphine, triethylphosphine, triphenylphosphine and the like mono-, di- or trialkyl (aryl) phosphine; methyldichlorophosphine, ethyldichlorophosphine, phenyldichlorophosphine, Alkyl (aryl) halogen phosphines such as dimethylchlorophosphine, diethylchlorophosphine, diphenylchlorophosphine; Mono-, di- or tri-alkyl (aryl) oxides such as ruphosphine, ethylphosphine oxide, phenylphosphine oxide, dimethylphosphine oxide, diethylphosphine oxide, diphenylphosphine oxide, trimethylphosphine oxide, triethylphosphine oxide, triphenylphosphine oxide Phosphine; tetraalkyl (aryl) phosphonium halides such as tetramethylphosphonium chloride, tetraethylphosphonium chloride, tetraphenylphosphonium chloride; and the like. 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 0.01. -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, making 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 hydroxy group present in the molecular chain of the polymer (a) obtained in the polymerization step A form in which an ester 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 hydroxy group and the 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 using the devolatilization step at the same time is a preferred mode for obtaining a 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.

  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 hydroxy group and the 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 a form in which a combined cyclization condensation reaction is carried out, a polymer obtained by a cyclization condensation reaction carried out in advance (a polymer in which at least a part of a hydroxy group and an ester group present in a molecular chain is subjected to a cyclization 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 hydroxy group and ester group present in the molecular chain is present). It may be introduced into a cyclization condensation reaction in which a devolatilization step is used at the same time after other treatments such as re-addition of a solvent after the cyclization condensation reaction polymer is isolated.

  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.

  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 according to the present invention 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. In addition, it is preferable that it is 200 degrees C or less from a flexible point. More preferably, it is 170 degrees C or less. If the glass transition temperature is too high, film formation may be difficult.

  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.

<Base film with lactone ring-containing polymer as main component>
It is preferable that the base film used for the transparent conductive film according to the present invention contains the above-mentioned lactone ring-containing polymer as a main component.

  The content ratio of the lactone ring-containing polymer in the base 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. . When the content ratio of the lactone ring-containing polymer in the base film is less than 50% by mass, the effects of the present invention may not be sufficiently exhibited.

  The base film containing the lactone ring-containing polymer as a main component may contain a polymer other than the lactone ring-containing polymer (hereinafter sometimes referred to as “other polymer”) as the other component. 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 average particle size of the rubber polymer is preferably 100 nm or less, and more preferably 70 nm or less, from the viewpoint of improving the transparency when it is formed into a film. Further, the rubbery polymer preferably has a graft portion on the surface thereof having a composition compatible with the polymer having a lactone ring structure used in the present invention.

  Among the other polymers mentioned above, polymers that are thermodynamically compatible with a polymer having a lactone ring structure (or a copolymer having a lactone ring structure) reduce the transparency and mechanical strength of the resulting resin film. It is preferable because it is difficult to make it. Note that the polymer (or copolymer) having a lactone ring structure and other polymers are thermodynamically compatible with each other because the Tg of the resin composition obtained by mixing them is differential scanning calorimetry. This can be confirmed by the fact that the observed Tg is one point when measured with a measuring instrument.

  The content ratio of the other polymer in the base 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 base film mainly composed of a lactone ring-containing polymer 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 base film mainly composed of a lactone ring-containing polymer is preferably 0 to 5% by mass, more preferably 0 to 2% by mass, and still more preferably 0 to 0.5% by mass. is there.

  The method for producing a base film mainly composed of a lactone ring-containing polymer is not particularly limited. For example, a lactone ring-containing polymer and, if necessary, other polymers and additives, A method of forming a thermoplastic resin composition in advance by mixing it well by a conventionally known mixing method, and then forming this into a film; dissolving or dispersing a lactone ring-containing polymer and other polymers and additives in a solvent, respectively. Thereafter, these are mixed to obtain a uniform mixed solution, which is then formed into a film. Moreover, it is good also as a stretched film by extending | stretching the unstretched film obtained as mentioned above.

  In order to produce the thermoplastic resin composition, for example, the above-mentioned film raw material is pre-blended with a conventionally known mixer such as an omni mixer, and then the obtained mixture is extruded and 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 can be used. .

  Specific 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 base film mainly composed of the lactone ring-containing polymer 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. A base film mainly composed of a lactone ring-containing polymer can suppress an increase in retardation even when stretched by mixing other thermoplastic resins, and retain optical isotropy. Can do.

  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 containing a lactone ring-containing polymer as a main component may be subjected to a heat treatment (annealing) or the like after the stretching treatment in order to stabilize its optical isotropy and mechanical properties. 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 base film mainly composed of a lactone ring-containing polymer has a thickness of preferably 5 to 200 μm, more preferably 10 to 100 μm. If the thickness is less than 5 μm, the strength of the film decreases. On the other hand, if the thickness exceeds 200 μm, the transparency of the film may be reduced, the touch panel may be thick, and the cost may be a problem.

  In addition, the base film mainly composed of the lactone ring-containing polymer according to the present invention is, for example, corona discharge treatment, ozone spraying, ultraviolet irradiation, flame treatment, chemical treatment, and other conventionally known ones. Surface treatment can be applied.

  Although the base film according to the present invention has high transparency, it conforms to ASTM-D-1003 from the viewpoint of use as a touch panel used in combination with an image display device such as a liquid crystal display or a flat panel display. The visible light transmittance (average transmittance at 400 to 700 nm) measured by the method is preferably 80% or more, more preferably 90% or more, and particularly preferably 92% or more.

The base film according to the present invention preferably has a photoelastic coefficient of −1.0 × 10 ⁻¹⁰ m ² / N or more and 1.0 × 10 ⁻¹⁰ or less. More preferably, it is −1.0 × 10 ⁻¹¹ m ² / N or more and 1.0 × 10 ⁻¹¹ or less, and further preferably −1.0 × 10 ⁻¹² m ² / N or more, 1.0 × 10. ^-12 m ² / N or less. The photoelastic coefficient is a value specific to the material and is a measure of the likelihood of stress birefringence. Since the base film according to the present invention is also used for optical applications such as a touch panel used in combination with various display devices, it is desirable that stress birefringence is reduced as much as possible, and photoelasticity The smaller the coefficient, the better. When the photoelastic coefficient is larger than 10 ⁻¹⁰ m ² / N, the phase difference when a load is applied to the base film becomes large, which is sufficient when the base film is used in combination with a display device. Visual characteristics may be difficult to obtain.

The stress birefringence refers to birefringence that is manifested by stress loading, and is manifested when stress strain remains in the base film or when an external force is applied. The stress birefringence is a value represented by the following formula.
Δn = C · δ
(In the above formula, Δn represents stress birefringence, C represents a photoelastic coefficient (m ² / N), and δ represents stress (gf).)

  In general, the photoelastic coefficient can be obtained by the Esprit method. With the Esprit method, a test piece of an appropriate size is set on a tension jig, the change in retardation when a plurality of stresses are applied is measured with a phase difference measuring device, and the obtained value is expressed as the vertical axis: retardation, Horizontal axis: Plotted as stress and can be obtained as slope when approximated by a straight line.

  The glass transition temperature (Tg) of the substrate film according to the present invention is preferably 120 ° C. or higher, more preferably 125 ° C. or higher, more preferably 130 ° C. or higher, and preferably 200 ° C. or lower, More preferably, it is 170 degrees C or less. If the glass transition temperature of the base film is too high, the flexibility of the base film may be reduced.

  The base film according to the present invention preferably has a tensile strength measured based on ASTM-D-882-61T of 10 MPa or more and less than 300 MPa, more preferably 30 MPa or more and 250 MPa or less. If it is less than 10 MPa, it is not preferable because sufficient mechanical strength may not be exhibited. When it exceeds 300 MPa, workability is deteriorated, which is not preferable.

  Further, the base film according to the present invention preferably has a retardation per 100 μm thickness in the plane direction of −100 nm or more and 100 nm or less, more preferably −50 nm or more, 50 nm or less, and further preferably −10 nm or more. 10 nm or less. The retardation in the plane direction is an index of birefringence, and the base film according to the present invention has low birefringence. When the phase difference per 100 μm thickness in the plane direction is less than −100 nm or exceeds 100 nm, the anisotropy of the refractive index increases, which may be difficult to use for applications requiring low birefringence.

  The base film according to the present invention preferably has a retardation distribution in the same plane of 10 nm or less. More preferably, it is 5 nm or less.

  The content of the volatile component at 260 ° C. or less of the base film according to the present invention is preferably 3000 ppm or less. More preferably, it is 2000 ppm or less, More preferably, it is 1000 ppm or less. When the amount of volatile components contained in the base film is large, formation of a transparent conductive layer having uniform conductivity and transparency may be hindered when a transparent conductive layer described later is formed. Moreover, it may foam and the transparency of the base film may be lost or deformed, and the mechanical strength may be lowered. In addition, content of a volatile component is measured by the method as described in the Example mentioned later.

<Transparent conductive layer>
The transparent conductive film of the present invention has a transparent conductive layer on at least one side of the substrate film. As the material constituting the transparent conductive layer, any material conventionally used as a conductive material in the field can be used, and specifically, an organic conductive compound, an organic conductive polymer, indium oxide. , Tin oxide, zinc oxide, indium-tin oxide (ITO), antimony-tin oxide (ATO), zinc-aluminum oxide, indium-zinc oxide (IZO), etc .; gold, silver, copper , Metals such as palladium and aluminum. Among these, those containing zinc oxide or indium oxide as a main component are preferable, and those containing indium oxide as a main component are particularly preferable. Among these, indium-tin oxide is preferable because it has both high transparency and conductivity.

  The “main component” means that the transparent conductive layer contains 60% by mass or more of indium oxide, preferably the content of indium oxide is 80 to 99% by mass, more preferably 90 to 90% by mass. 95% by mass.

  The thickness of the transparent conductive layer is preferably 20 to 300 nm. More preferably, it is 25-200 nm, More preferably, it is 30-100 nm. If the thickness of the transparent conductive layer is too thin, the thickness and composition may be non-uniform. On the other hand, if it is too thick, the transparency may be lost.

  In the present invention, examples of a method for forming a transparent conductive layer on a substrate film include thin film forming means such as a coating method, a vacuum deposition method, a sputtering method, and an ion plating method. Among these, it is preferable to employ a sputtering method that can easily control the film thickness and composition of the transparent conductive layer, and is excellent in adhesion to the substrate film and productivity.

  When adopting the sputtering method, using a normal sputtering method using a metal oxide target having the same composition as the desired transparent conductive layer, or using a metal target, a mixture of sputtering gas, oxygen, nitrogen, etc., A transparent conductive layer having a desired composition may be formed by reacting on a target or a substrate. The sputtering method is not particularly limited, and plasma methods such as dipole sputtering, tripolar sputtering, quadrupole sputtering, magnetron sputtering, opposed target sputtering (FTS) method, unbalanced magnetron sputtering, ion beam sputtering, ECR (electron). (Cyclotron resonance) Beam method such as sputtering. Among these, the magnetron sputtering method and the opposed target sputtering (FTS) method are preferable. The power source to be used may be either a high frequency power source (RF) or a direct current power source (DC).

  A rare gas such as argon, helium, or neon is used as a sputtering gas for forming the transparent conductive layer by sputtering. Further, oxygen or nitrogen may be used as the reactive gas. In addition, it is preferable that the vacuum degree at the time of sputtering shall be 0.01-2.0 Pa. More preferably, it is 0.1-1.0 Pa. When the degree of vacuum is within the above range, discharge occurs stably, so that sputtering is stable and a transparent conductive film (layer) having a uniform film thickness and composition is easily obtained. Moreover, the adhesiveness of a transparent conductive layer and a base film tends to become favorable. In addition, when the base film according to the present invention contains a lactone ring, intermolecular force works between the lactone ring and the metal oxide, so that the adhesion between the base film and the transparent conductive film is better. It becomes.

  In the step of laminating the transparent conductive layer, the surface temperature of the base film is preferably within a range not exceeding the glass transition temperature of the base film + 30 ° C. More preferably, it is the range which does not exceed the glass transition temperature +20 degreeC of a base film, Most preferably, it is the range which does not exceed the glass transition temperature of a base film. If the glass transition temperature of the base film exceeds 30 ° C., the base film may be deformed or the surface smoothness of the base film may be lost.

<Transparent conductive film>
As described above, the transparent conductive film of the present invention comprises a base film mainly composed of an acrylic resin having a ring structure in the main chain and a glass transition temperature of 120 ° C. or higher, more preferably a lactone ring structure-containing polymer. It has a transparent conductive layer on at least one side of a base film as a main component. The transparent conductive film of the present invention has a visible light transmittance of preferably 80% or more, more preferably 85% or more, still more preferably 90% or more, as measured by a method based on ASTM-D-1003. is there. When the total light transmittance is less than 80%, the transparency is lowered, and it may be difficult to use in applications requiring high transparency.

  Furthermore, the transparent conductive film of the present invention preferably has a phase difference of -100 nm or more and 100 nm or less, more preferably -50 nm or more and 50 nm, per 100 μm thickness in the plane direction measured by a retardation measuring device. Hereinafter, it is more preferably −10 nm or more and 10 nm or less. The retardation in the plane direction is an index of birefringence, and the transparent conductive film according to the present invention has low birefringence. When the phase difference per 100 μm thickness in the plane direction is less than −100 nm or exceeds 100 nm, the anisotropy of the refractive index increases, which may be difficult to use for applications requiring low birefringence.

  The conductive film of the present invention preferably has a retardation distribution in the same plane of less than 10 nm. More preferably, it is 5 nm or less.

<Touch panel>
Since the transparent conductive film of the present invention has high transparency and has both durability and low birefringence, it is suitably used for a touch panel used in combination with various display devices. Moreover, since the adhesiveness of a base film and a transparent conductive layer is favorable, even if it inputs repeatedly with a pen etc., peeling of the transparent conductive layer by the friction between electrodes (transparent conductive layer) does not arise easily. In the touch panel using the transparent conductive film of the present invention, the upper and lower transparent conductive films face each other, the transparent conductive layers face each other, and a predetermined gap is maintained between the upper and lower transparent conductive layers. Thus, it has the structure laminated | stacked through the spacer. When the laminated structure is used as a touch panel, the transparent conductive layer non-formation surface of one (upper) transparent conductive film is pressed with a finger or a pen, and the upper and lower transparent conductive layers are brought into contact with the pressing. , Input information with a finger or a pen is recognized. That is, since the upper and lower transparent conductive layers are short-circuited at the contact portion, this is processed as an electric signal, and the input content by the finger or the pen is recognized. In addition, as described above, the touch panel according to the present invention may be composed of two transparent conductive films. Further, the surface of the film is glaring or reflected, scratch resistance, fingerprint resistance, repeated use. In order to improve durability at the time, a surface treatment (hard coat treatment, fingerprint adhesion treatment) may be applied to the surface where the transparent conductive layer is not formed, or a functional layer may be provided. Moreover, in order to ensure the ease of input at the time of use, glass and a polymer resin film can also be laminated | stacked on a transparent conductive layer non-formation surface.

  Since the touch panel of the present invention uses the transparent conductive film of the present invention which is excellent in transparency and optically isotropic (substantially has no birefringence), it is used as a liquid crystal display. Even when used over a display device such as a panel, a plasma display panel, or a CRT, the contrast is hardly lowered and the display has excellent visibility such as high visibility.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these. Hereinafter, for convenience, “parts by mass” may be referred to as “parts”, “mass%” as “wt%”, and “liter” as simply “L”.

<Refractive index anisotropy (phase difference)>
Refractive index anisotropy (retardation: Re) was measured using a phase difference measuring device (“KOBRA-WR” manufactured by Oji Scientific Instruments) as a wavelength of 590 nm and a sample measurement area of 3.3 mm ² by the balanced Nicol rotation method. Measurements were made.

<Measurement method of phase difference distribution>
Using a phase difference measurement device (“KOBRA-WR” manufactured by Oji Scientific Instruments), three points in a test piece having a sample size of 25 cm ² were measured at a wavelength of 590 nm and a measurement area of 3.3 mm ² by the balanced Nicol rotation method. The difference between the maximum value and the minimum value was measured as a phase difference distribution.

<Photoelastic coefficient>
Using an ellipsometer (manufactured by JEOL Ltd. "M-150"), a variety of tensile strength ^{(0N / mm 2, 2.5N /} mm 2, 5.0N / mm 2, 7.5N / mm 2, 10.0N / Mm ² ) was measured for a photoelastic modulus of 400 nm, plotted (vertical axis: retardation, horizontal axis: tensile strength), and a photoelastic coefficient was determined from the slope of the straight line.

<Transmission in the visible region>
The visible light transmittance was determined by measuring a transmission spectrum at a wavelength of 350 to 1100 nm using a spectrophotometer (“UV-3100” manufactured by Shimadzu Corporation), and obtaining an average transmittance at a wavelength of 400 to 700 nm.

<Glass glass transition temperature>
The glass transition temperature of the film was determined by using a differential scanning calorimeter (DSC) (“DSC-8230” manufactured by Rigaku Corporation) under the conditions of about 10 mg of sample, a heating rate of 20 ° C./min, and a nitrogen flow of 50 cc / min. Thus, the midpoint method was used.

<Amount of volatile components>
Using a measuring apparatus: Thermo Plus 2TG-812 Dynamic TG (manufactured by Rigaku Corporation, apparatus name: DSC-8230), the mass reduced until reaching 260 ° C. under the following conditions was defined as the amount of volatile components.
Measurement conditions Sample amount: 10mg
Temperature increase rate: 20 ° C / min
Atmosphere: Nitrogen flow 200ml / min

Production Example 1
20 parts of methyl 2- (hydroxymethyl) acrylate, 80 parts of methyl methacrylate, and 100 parts of toluene were charged into a 30 L reaction kettle equipped with a stirrer, temperature sensor, cooling pipe, and nitrogen gas introduction pipe. While introducing the nitrogen gas into this reaction vessel, the mixed solution was heated to 105 ° C. and refluxed. As a polymerization initiator, t-amyl peroxyisononanoate (“Lupazole 570”, “Lupazole” manufactured by Arkema Yoshitomi Co., Ltd.) was used. "Akema Incorporated (registered trademark)" 0.1 part was added, and at the same time, a solution comprising 1 part of toluene and 0.2 part of t-amylperoxyisononanoate was dropped into the reaction vessel over 2 hours. Then, solution polymerization was carried out at 105 to 110 ° C. under reflux, followed by further aging for 4 hours.

  To the obtained polymer solution, 0.1 part of a stearyl phosphate / distearyl phosphate mixture (“Phoslex A-18” manufactured by Sakai Chemical Industry Co., Ltd.) was added and refluxed at 100 to 110 ° C. for 5 hours. Cyclocondensation 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 = 30 mm, L / D = 42) Introduced at a processing rate of 2.0 kg / h in terms of resin amount, and after further cyclization condensation reaction and deaeration in this extruder, extrude. As a result, a transparent pellet (a) of the lactone ring-containing polymer was obtained.

  A mixture of 90 parts of the obtained pellet (a), AS resin (acrylonitrile-styrene resin, “Stylac 783” manufactured by Asahi Kasei Corporation, “Stylac” is a registered trademark of Asahi Kasei Chemicals Corporation), and 400 ppm of zinc acetate. Using a bent type screw twin screw extruder (φ = 30 mm, L / D = 42), melt kneading was performed at an extrusion temperature of 260 ° C. to obtain pellets (A).

<Manufacture of base film>
For the production of the base film, a Toyo Seiki Seisakusho's kneader "Lab Plast Mill 20C200 type" and a Toyo Seiki Seisakusho's "D20-25 type vent type extruder" are used as an extruder. It was.

  The pellet (A) was introduced into an extruder heated to a cylinder temperature of 270 ° C., and the gas generated in the extruder was discharged from the vent port, and the temperature was adjusted to 280 ° C. while the pressure in the extruder was reduced to 0.001 MPa. Film-extruded from a T-die (“T150C type” manufactured by Toyo Seiki Seisakusho), and formed into a film with a casting take-up device (“FT2B15 type” manufactured by Toyo Seiki Seisakusho) with the temperature of the casting roll adjusted to 95 ° C. A base film was obtained.

  Next, the obtained film was cut into 90 × 90 mm and longitudinally stretched at a temperature of 160 ° C. using a simultaneous biaxial stretching machine (manufactured by Toyo Seiki Seisakusho) having 10 (total 40) chuck clips on one side. And it extended | stretched 1.9 * 1.9 time in the horizontal direction, and the 50-micrometer-thick stretched film (A) was obtained.

  The stretched film (A) had a glass transition temperature (Tg) of 127 ° C., and the amount of volatile components at 260 ° C. or lower was 2300 ppm.

Production Example 2
In a reaction vessel similar to Production Example 1, 15 parts of methyl 2- (hydroxymethyl) acrylate, 80 parts of methyl methacrylate, and 100 parts of toluene were charged. While introducing the nitrogen gas into the reaction vessel, the mixed solution was heated to 105 ° C. and refluxed. As a polymerization initiator, t-amylperoxyisononanoate (“Lupazole (registered trademark) 570 manufactured by Arkema Yoshitomi Co., Ltd.) was used. )) While adding 0.1 part, a solution consisting of 0.2 part of t-amylperoxynonanoate, 1 part of toluene, and 5 parts of styrene was dropped into the reaction vessel over 2 hours while refluxing. Solution polymerization was performed at ˜110 ° C., and further aging was performed for 4 hours.

  To the obtained polymer solution, 0.1 part of a stearyl phosphate / distearyl phosphate mixture (“Phoslex A-18” manufactured by Sakai Chemical Industry Co., Ltd.) was added and refluxed at 100 to 110 ° C. for 5 hours. Cyclocondensation 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 = 30 mm, L / D = 42) in terms of resin amount, introduced at a processing rate of 2.0 kg / h, and after further cyclization condensation reaction and devolatilization in this extruder, it is extruded A transparent pellet (B) of the lactone ring-containing polymer was obtained.

<Manufacture of base film>
Using the obtained pellet (B), a stretched film (B) having a thickness of 50 μm was obtained in the same manner as in Production Example 1. The stretched film (B) obtained had a glass transition temperature (Tg) of 125 ° C., and the volatile component content at 260 ° C. or lower was 2000 ppm.

Example 1
An ITO layer was formed on the stretched film (A) obtained in Production Example 1 using a sputtering apparatus (opposite target type sputtering apparatus, manufactured by Osaka Vacuum Equipment Co., Ltd.). For the sputtering, an indium oxide-tin oxide target containing 10% by mass of tin oxide was used, and the vacuum was 0.5 Pa and an argon gas atmosphere containing 5% by volume of oxygen was added at a rate of 0.4 liter / sec. Sputtering was performed for 20 minutes to obtain a transparent conductive film (A) having an ITO transparent conductive layer (thickness 50 nm).

Example 2
An ITO layer (thickness 50 nm) was formed on the stretched film (B) by the same method and conditions as in Example 1 to obtain a transparent conductive film (B).

Comparative Example 1
Using a PET film with a film thickness of 50 μm (Toray Industries, Inc. “Lumirror”, “Lumirror” is a registered trademark of Toray Industries, Inc.), an ITO layer (thickness 50 nm) is formed on the PET film in the same manner as in Example 1. A transparent conductive film (C) was obtained.

  Table 1 shows the physical properties of the transparent conductive films (A) to (C) obtained in the above Examples and Comparative Examples.

  From Table 1, the transparent conductive films (A) and (B) of Examples 1 and 2 are 100 μm per 100 μm compared with the transparent conductive film (C) of Comparative Example 1 using a PET film as a base material. It has a small phase difference, a small photoelastic coefficient, high optical isotropy (low birefringence) and visible light transmittance. Therefore, it is considered that the transparent conductive film of the present invention is suitable for a touch panel used in combination with various display elements.

  The transparent conductive film of the present invention uses, as a base material, a resin film mainly composed of a lactone ring-containing polymer having excellent heat resistance and various optical properties (transparency, optical isotropy, low birefringence). Therefore, even after forming a transparent conductive layer made of a metal oxide such as an ITO layer, the substrate film hardly changes in dimensions and has excellent optical properties (transparency, optical isotropy, low birefringence). Therefore, it is suitable as a touch panel used in combination with a display element such as a liquid crystal display or a plasma display.

Claims (9)

  A transparent conductive film comprising a transparent conductive layer on at least one surface of a base film having a cyclic structure in the main chain and a glass transition temperature of 120 ° C. or higher as a main component.   The transparent conductive film according to claim 1, wherein the acrylic resin having a glass transition temperature of 120 ° C. or higher is mainly composed of a lactone ring structure-containing polymer.   The transparent conductive film according to claim 1, which has a visible light transmittance of 80% or more. The transparent conductive film according to claim 1, which has a photoelastic coefficient of −1.0 × 10 ⁻¹⁰ m ² / N or more and 1.0 × 10 ⁻¹⁰ m ² / N or less.   The phase difference is 0-100 nm, The transparent conductive film in any one of Claims 1-4.   The transparent conductive film according to claim 1, wherein the transparent conductive layer is made of indium-tin oxide. The transparent conductive film according to any one of claims 2 to 6, wherein the lactone ring-containing polymer has a lactone ring structure represented by 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 is hydrogen, oxygen, nitrogen, sulfur, phosphorus And may contain halogen atoms]   The transparent conductive film according to claim 1, wherein the base film is stretched.   A touch panel comprising the transparent conductive film according to claim 1.