JP2016155328A - Transparent conductive film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transparent conductive film having acrylic resin used as a base film, the transparent conductive film having excellent heat resistance and suppressing the occurrence of interference unevenness.SOLUTION: A transparent conductive film has a primer layer, a hard coat layer, and a transparent conductive layer put on at least one side of a base film in the stated order, where the base film comprises acrylic resin having a ring structure in a main chain, and having a glass transition temperature of 140°C or more.SELECTED DRAWING: None

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. In a touch panel, a transparent conductive film in which a transparent conductive layer is provided on a transparent base film is generally used, and the transparent conductive layer is a composite oxide of indium and tin (hereinafter referred to as “ITO”). A transparent conductive layer is formed on the base film by performing processing such as sputtering, ion plating, and vacuum deposition using a metal oxide.

  As the base film constituting the transparent base material, for example, a film such as a PET film or a polycarbonate film is used from the viewpoint of high transparency and price. In recent years, the base film is made transparent. In addition, an acrylic resin such as polymethyl methacrylate (PMMA) has attracted attention as a film material having a low refractive index. The acrylic resin is suitable as a base film for a transparent conductive film because it is excellent in optical properties such as light transmittance and has a good balance of mechanical strength, molding processability and surface hardness. On the other hand, since acrylic resins have low heat resistance, there is a problem that it is difficult to obtain a transparent conductive film by forming a conductive film (transparent conductive layer) by sputtering or the like. Therefore, as an acrylic resin having excellent heat resistance and capable of forming a conductive film by sputtering or the like, Patent Document 1 discloses an acrylic resin having a ring structure such as a lactone ring in the main chain and having a glass transition temperature of 120 ° C. or higher. A transparent resin in which a transparent conductive layer is provided on at least one surface of a base film formed from the acrylic resin is disclosed.

JP 2008-179677 A

  Although the transparent conductive film disclosed in Patent Document 1 has a certain degree of adhesion between the transparent conductive layer and the base film and has a certain durability, there is an increasing demand for the quality of the touch panel. Further, further heat resistance and durability are required for transparent conductive films. On the other hand, in the transparent conductive film, a transparent hard coat layer may be provided on the base film for the purpose of improving scratch resistance, durability, etc. In this case, on the hard coat layer, A transparent conductive layer will be provided. However, when a hard coat layer is provided on a base film formed from an acrylic resin and a transparent conductive layer made of ITO or the like is further provided thereon, interference unevenness (rainbow interference) is observed. It turns out that happens.

  The present invention has been made in view of the above circumstances, and the object thereof is a transparent conductive film using an acrylic resin as a base film, which has excellent heat resistance and suppresses occurrence of interference unevenness. The object is to provide a transparent conductive film.

  The present inventors have investigated the cause of interference unevenness (rainbow interference) when a hard coat layer and a transparent conductive layer are laminated on a base film formed from an acrylic resin. For example, when the ITO layer is crystallized on the hard coat layer, a slight interface shift occurs between the base film and the hard coat layer, and interference unevenness occurs due to light reflection at the interface. I found out that And it became clear that it is effective to provide a primer layer between the base film and the hard coat layer in order to suppress the occurrence of uneven interference.

  That is, the transparent conductive film of the present invention is a transparent conductive film in which a primer layer, a hard coat layer, and a transparent conductive layer are laminated in this order on at least one side of a base film, and the base film is a main film. It is characterized by containing an acrylic resin having a ring structure in the chain and a glass transition temperature of 140 ° C. or higher. In the transparent conductive film of the present invention, since a primer layer is provided between the hard coat layer on which the transparent conductive layer is formed and the base film, an interface shift occurs between the base film and the hard coat layer. However, it is possible to suppress the occurrence of a slight gap between the base film and the hard coat layer by the primer layer, and it is possible to prevent the occurrence of interference unevenness. Moreover, since acrylic resin which comprises a base film has high heat resistance, even if it forms a conductive film by sputtering etc., transparency and flatness of a base film are ensured. As a result, it is possible to obtain a transparent conductive film that is excellent in heat resistance and in which occurrence of interference unevenness is suppressed.

  The acrylic resin preferably has a repeating unit represented by the following formula (1) and a repeating unit represented by the following formula (2). If the acrylic resin has a repeating unit represented by the following formula (1) and a repeating unit represented by the following formula (2), the resulting base film can be added to transparency and heat resistance. Thus, it has a low birefringence. Therefore, the transparent conductive film has excellent optical characteristics.

[In Formula (1), R < ¹ > and R < ² > represent a hydrogen atom or a C1-C8 alkyl group each independently, and R < ³ > represents a ring structure. ]

[In the formula (2), R ⁴ and R ⁵ each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and R ⁶ represents an alkyl group having 1 to 18 carbon atoms or 3 to 3 carbon atoms. 12 represents a cycloalkyl group or an aryl group having 6 to 10 carbon atoms. ]

  The acrylic resin has a repeating unit represented by the formula (1) in a content of 5% by mass to 85% by mass and a repeating unit represented by the formula (2) in a content of 15% by mass to 95% by mass. It is preferable. If the repeating unit represented by the formula (1) and the repeating unit represented by the formula (2) are contained in such a content, the heat resistance and transparency of the base film are improved, and birefringence is improved. While being able to make small, the moldability to a film improves and the mechanical strength of a base film can be raised.

The acrylic resin preferably has an absolute value of stress optical coefficient (Cr) of 0.3 × 10 ⁻⁹ Pa ⁻¹ or less. If the value of the stress optical coefficient of the acrylic resin is in such a range, the anisotropy of the refractive index of the stretched film obtained by stretching the acrylic resin is suppressed, and birefringence can be reduced.

  The primer layer preferably contains a resin selected from the group consisting of polyester resins, acrylic resins, urethane resins, and composite resins thereof. If the primer layer is composed of such a resin, the adhesion of the primer layer to the base film or hard coat layer can be improved, and the occurrence of uneven interference in the transparent conductive film can be effectively suppressed. be able to. In addition, it is preferable that a primer layer contains water-soluble resin and / or microparticles | fine-particles further from the point which improves the adhesiveness of a primer layer.

  In the transparent conductive film of the present invention, since a primer layer is provided between the hard coat layer on which the transparent conductive layer is formed and the base film, an interface shift occurs between the base film and the hard coat layer. However, it is possible to suppress the occurrence of a slight gap between the base film and the hard coat layer by the primer layer, and it is possible to prevent the occurrence of interference unevenness. Moreover, since acrylic resin which comprises a base film has high heat resistance, even if it forms a conductive film by sputtering etc., transparency and flatness of a base film are ensured. As a result, it is possible to obtain a transparent conductive film that is excellent in heat resistance and in which occurrence of interference unevenness is suppressed.

  The transparent conductive film of the present invention is a transparent conductive film in which a primer layer, a hard coat layer, and a transparent conductive layer are laminated in this order on at least one surface of a base film, and the base film has a ring in the main chain. It has a structure and contains an acrylic resin having a glass transition temperature of 140 ° C. or higher. The transparent conductive film of the present invention contains an acrylic resin having excellent heat resistance as a base film, and a hard coat layer having a transparent conductive layer formed on the base film is laminated. Even if the conductive film is formed by the above method, the transparency and flatness of the base film are ensured, and a transparent conductive film excellent in heat resistance can be obtained. In addition, since the primer layer is provided between the hard coat layer on which the transparent conductive layer is formed and the base film, even if an interface shift occurs between the base film and the hard coat layer, the primer layer It is possible to suppress a slight gap between the material film and the hard coat layer, and to prevent occurrence of interference unevenness.

  For example, when the hard coat layer is formed directly on the base film, a slight gap that cannot be visually recognized is formed between the base film and the hard coat layer, and this slight gap causes the occurrence of interference unevenness. cause. However, by providing a primer layer between the base film and the hard coat layer, it is possible to suppress the occurrence of a slight gap between the base film and the hard coat layer, and to prevent occurrence of interference unevenness. Hereinafter, the transparent conductive film of this invention is demonstrated in detail for every component.

[1. (Base film)
As the base film, an acrylic resin having a ring structure in the main chain and having a glass transition temperature of 140 ° C. or higher is used. If the base film contains an acrylic resin having a ring structure in the main chain and a glass transition temperature of 140 ° C. or higher, a transparent conductive film excellent in heat resistance can be obtained.

  The acrylic resin that constitutes the base film may be any resin that is obtained by homo- or copolymerizing an α, β-unsaturated carbonyl compound. That is, the α, β-unsaturated carbonyl compound is preferably a (meth) acrylic acid compound such as (meth) acrylic acid and its ester, but may be a compound other than the (meth) acrylic acid compound. In compounds other than acrylic acid, a substituent other than a hydrogen atom may be bonded to the β-position carbon, and a substituent other than a hydrogen atom or a methyl group may be bonded to the α-position carbon. In addition, as a substituent other than the hydrogen atom which may be couple | bonded with (beta) -position carbon, a C1-C8 alkyl group is mentioned, for example. Examples of the substituent other than the hydrogen atom and the methyl group that may be bonded to the α-position carbon include an alkyl group having 2 to 8 carbon atoms. The carbonyl group of the α, β-unsaturated carbonyl compound may be present as, for example, a carboxylic acid or a salt thereof, an ester, an acid anhydride, or an acid chloride.

  In the acrylic resin, a part of the ring structure is preferably formed by the carbonyl carbon of the α, β-unsaturated carbonyl compound and the carbons at the α-position and the β-position. Examples of the ring structure of the main chain of the acrylic resin include an N-substituted maleimide structure, a maleic anhydride structure, a glutarimide structure, a glutaric anhydride structure, and a lactone ring structure. Examples of the N-substituted maleimide structure include a cyclohexylmaleimide structure, a methylmaleimide structure, a phenylmaleimide structure, and a benzylmaleimide structure. If the acrylic resin has a ring structure in the main chain, the heat resistance and hardness of the base film are improved. From the viewpoint of further improving the heat resistance of the base film, the ring structure of the main chain is preferably a glutarimide structure.

  The acrylic resin constituting the base film has a glass transition temperature of 140 ° C. or higher. If the glass transition temperature of the acrylic resin is 140 ° C. or higher, the heat resistance of the base film is improved, and even if a conductive film is formed on the base film by sputtering or the like, the transparency and flatness are excellent. It becomes easy to obtain a transparent conductive film. From the viewpoint of improving the heat resistance of the base film, the glass transition temperature of the acrylic resin is preferably 145 ° C. or higher, more preferably 150 ° C. or higher, and further preferably 155 ° C. or higher. In addition, the glass transition temperature of the acrylic resin is preferably 250 ° C. or less, more preferably 230 ° C. or less, further preferably 210 ° C. or less, and particularly preferably 200 ° C. or less, from the viewpoint of improving the moldability to a film. is there.

  The glass transition temperature of the acrylic resin is determined in accordance with JIS K 7121. Specifically, a differential scanning calorimeter (trade name: Thermo plus EVO DSC-8230, manufactured by Rigaku Corporation) is used, and α-alumina is used as a reference, and about 10 mg of acrylic resin from room temperature to 200 in a nitrogen gas atmosphere. The temperature is raised to 20 ° C. at a rate of temperature rise of 20 ° C./min, and the temperature obtained by the starting point method from the obtained DSC curve is defined as the glass transition temperature.

[1-1. Configuration of acrylic resin)
The acrylic resin has a ring structure in the main chain and can be used without particular limitation as long as the glass transition temperature is 140 ° C. or higher, but the repeating unit (glutarimide unit) represented by the following formula (1) And preferably having a repeating unit represented by the following formula (2). If acrylic resin has the repeating unit represented by Formula (1) and Formula (2), the obtained base film will have low birefringence in addition to transparency and heat resistance. That is, the acrylic resin having the repeating unit represented by the formula (1) and the formula (2) exhibits weak positive birefringence based on the repeating unit represented by the formula (1), and is represented by the formula (2). The birefringence of both of them is canceled out based on the repeating unit, and the birefringence of the two cancels each other, so that the whole has low birefringence.

[In Formula (1), R < ¹ > and R < ² > represent a hydrogen atom or a C1-C8 alkyl group each independently, and R < ³ > represents a ring structure. ]

[In the formula (2), R ⁴ and R ⁵ each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and R ⁶ represents an alkyl group having 1 to 18 carbon atoms or 3 to 3 carbon atoms. 12 represents a cycloalkyl group or an aryl group having 6 to 10 carbon atoms. ]

In the repeating unit represented by the formula (1), R ¹ and R ² each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. Examples of the alkyl group having 1 to 8 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, n-pentyl group, isopentyl group, n- Examples include a hexyl group, an isohexyl group, an n-heptyl group, an isoheptyl group, an n-octyl group, and a 2-ethylhexyl group. Especially, as R < ¹ > and R < ² >, a hydrogen atom or a C1-C4 alkyl group is preferable, and it becomes easy to obtain a base film which is excellent in heat resistance and has small birefringence.

In the repeating unit represented by the formula (1), R ³ represents a ring structure. Examples of the ring structure include a cycloalkyl group having 3 to 12 carbon atoms and an aryl group having 6 to 10 carbon atoms. Examples of the cycloalkyl group having 3 to 12 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group. Examples of the aryl group having 6 to 10 carbon atoms include phenyl, benzyl, o-tolyl, m-tolyl, p-tolyl, 2,3-xylyl, 2,4-xylyl, 2,5- Examples include xylyl group, 2,6-xylyl group, 3,4-xylyl group, 3,5-xylyl group, 1-naphthyl group, 2-naphthyl group, binaphthyl group, anthryl group and the like. R ³ is preferably a cycloalkyl group having 3 to 12 carbon atoms (more preferably a cycloalkyl group having 3 to 6 carbon atoms) or an aryl group having 6 to 10 carbon atoms, and further a cyclohexyl group, a phenyl group or a tolyl group. A cyclohexyl group or a phenyl group is particularly preferable. When R ³ is such a substituent, it becomes easy to obtain a base film having excellent heat resistance and low birefringence.

In the repeating unit represented by the formula (1), from the viewpoint of obtaining a base film having excellent heat resistance and low birefringence, R ¹ and R ² are each independently a hydrogen atom or a group having 1 to 4 carbon atoms. An alkyl group is preferred, a hydrogen atom or a methyl group is more preferred, R ³ is preferably a cyclohexyl group or a phenyl group, and a phenyl group is more preferred. In addition, acrylic resin may contain 2 or more types of repeating units represented by Formula (1).

In the repeating unit represented by the formula (2), R ⁴ and R ⁵ each independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. Examples of the alkyl group having 1 to 8 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, n-pentyl group, isopentyl group, n- Examples include a hexyl group, an isohexyl group, an n-heptyl group, an isoheptyl group, an n-octyl group, and a 2-ethylhexyl group. Among them, as R ⁴ and R ⁵ , a hydrogen atom or an alkyl group having 1 to 4 carbon atoms is preferable, thereby reducing the stress optical coefficient of the acrylic resin, excellent heat resistance, and low birefringence, It becomes easy to obtain a base film having a small photoelastic coefficient.

In the repeating unit represented by the formula (2), R ⁶ represents an alkyl group having 1 to 18 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, or an aryl group having 6 to 10 carbon atoms. Examples of the alkyl group having 1 to 18 carbon atoms include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl, hexyl, heptyl, and octyl. Group, decyl group, dodecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group and the like. Examples of the cycloalkyl group having 3 to 12 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group. Examples of the aryl group having 6 to 10 carbon atoms include phenyl, benzyl, o-tolyl, m-tolyl, p-tolyl, 2,3-xylyl, 2,4-xylyl, 2,5- Examples include xylyl group, 2,6-xylyl group, 3,4-xylyl group, 3,5-xylyl group, 1-naphthyl group, 2-naphthyl group, binaphthyl group, anthryl group and the like. Among these, as R < ⁶ >, a C1-C18 alkyl group is preferable, a C1-C8 alkyl group is more preferable, a C1-C4 alkyl group is more preferable, a methyl group, an ethyl group Alternatively, an n-butyl group is particularly preferable, which makes it easy to obtain a base film having a small stress optical coefficient of the acrylic resin, excellent heat resistance, small birefringence, and a small photoelastic coefficient.

In the repeating unit represented by the formula (2), R ⁴ and R are obtained from the viewpoint of obtaining a base film having a small stress optical coefficient of acrylic resin, excellent heat resistance, low birefringence, and low photoelastic coefficient. ⁵ are each independently preferably a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, still more preferably a hydrogen atom or a methyl group, R ⁶ is preferably an alkyl group having 1 to 18 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, or an aryl group having 6 to 10 carbon atoms, more preferably an alkyl group having 1 to 18 carbon atoms, An alkyl group having 1 to 8 carbon atoms is more preferable, an alkyl group having 1 to 4 carbon atoms is still more preferable, and a methyl group, an ethyl group, or an n-butyl group is particularly preferable. In addition, acrylic resin may contain 2 or more types of repeating units represented by Formula (2).

  In the acrylic resin, the content of the repeating unit represented by the formula (1) is preferably 5% by mass or more, more preferably 10% by mass or more, further preferably 15% by mass or more, and 85% by mass or less. Is preferable, 80 mass% or less is more preferable, and 75 mass% or less is further more preferable. If the content rate of the repeating unit represented by Formula (1) is 5 mass% or more, heat resistance and transparency will improve and it will become easy to make birefringence of a base film small. When the content of the repeating unit represented by the formula (1) is 85% by mass or less, the formability to the film is improved, the mechanical strength is easily increased, and the birefringence of the base film is reduced. Becomes easier.

  In the acrylic resin, the content of the repeating unit represented by the formula (2) is preferably 15% by mass or more, more preferably 20% by mass or more, further preferably 25% by mass or more, and 95% by mass or less. Is preferable, 90 mass% or less is more preferable, and 85 mass% or less is further more preferable. If the content of the repeating unit represented by the formula (2) is 15% by mass or more, the moldability to the film is improved, the mechanical strength is easily increased, and the birefringence of the base film is reduced. Becomes easier. If the content rate of the repeating unit represented by Formula (2) is 95 mass% or less, heat resistance and transparency will improve and it will become easy to make birefringence of a base film small.

  The acrylic resin may contain a repeating unit other than the repeating units represented by the formulas (1) and (2). In addition, it is preferable that acrylic resin contains the repeating unit represented by Formula (1) and Formula (2) as a main component, Therefore, in the acrylic resin, the repeating unit represented by Formula (1) and Formula ( The combined content of the repeating unit represented by 2) is preferably 50% by mass or more, more preferably 60% by mass or more, and further preferably 70% by mass or more. The acrylic resin may have, for example, a styrene unit as a repeating unit, but it is preferable that the styrene unit is not included so much. Accordingly, the content of styrene units in the acrylic resin is preferably 10% by mass or less, more preferably 5% by mass or less, further preferably 2% by mass or less, and particularly preferably 1% by mass or less.

  From the viewpoint of increasing the mechanical strength of the base film, the weight average molecular weight of the acrylic resin is preferably 10,000 or more, more preferably 30,000 or more, and from the viewpoint of improving the moldability to the film, 000 or less is preferable, and 300,000 or less is more preferable. The weight average molecular weight of acrylic resin is calculated | required based on the method as described in an Example.

  The acid value of the acrylic resin is preferably 1.4 mmol / g or less, more preferably 0.8 mmol / g or less, more preferably 0.5 mmol / g from the viewpoint of improving processability when the resin is film-formed. g or less is more preferable, and 0.3 mmol / g or less is particularly preferable. The acid value of the acrylic resin is determined based on the method described in the examples.

The absolute value of the stress optical coefficient (Cr) of the acrylic resin is 0.3 × 10 ⁻ from the viewpoint of suppressing the birefringence by suppressing the anisotropy of the refractive index of the stretched film obtained by stretching the resin. ⁹ Pa ⁻¹ or less is preferable, 0.2 × 10 ⁻⁹ Pa ⁻¹ or less is more preferable, and 0.1 × 10 ⁻⁹ Pa ⁻¹ or less is more preferable. The stress optical coefficient (Cr) of the acrylic resin is determined based on the method described in the examples.

[1-2. Manufacturing method of acrylic resin (glutarimide resin)]
The acrylic resin having the repeating unit represented by the formula (1) and the repeating unit represented by the formula (2) is obtained by, for example, converting an acrylic resin having the repeating unit represented by the formula (2) with an imidizing agent. It can be obtained by imidization. The acrylic resin having a repeating unit represented by the formula (2) can be obtained, for example, by polymerizing a monomer represented by the following formula (3). In this case, another monomer other than the monomer represented by the formula (3) may be contained. For example, when (meth) acrylic acid is used as the other monomer, the monomer represented by the formula (3) is used. In addition to the monomer to be produced, (meth) acrylic acid can be contained at a content of 45% by mass or less, preferably 40% by mass or less.

[Wherein, R ⁴ , R ⁵ and R ⁶ are the same as described above. ]

  The monomer represented by the formula (3) includes alkyl (meth) acrylates having 1 to 18 carbon atoms in the alkyl group, cycloalkyl (meth) acrylates having 3 to 12 carbon atoms in the cycloalkyl group, and carbons in the aryl group. Examples include aryl (meth) acrylates having 6 to 10 numbers.

  Examples of the alkyl (meth) acrylate having an alkyl group having 1 to 18 carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl ( (Meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, decyl (meth) acrylate, dodecyl ( Examples include meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, and octadecyl (meth) acrylate. Examples of the cycloalkyl (meth) acrylate having 3 to 12 carbon atoms in the cycloalkyl group include cyclopropyl (meth) acrylate, cyclobutyl (meth) acrylate, cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, and the like. . Examples of the aryl (meth) acrylate having 6 to 10 carbon atoms in the aryl group include phenyl (meth) acrylate, benzyl (meth) acrylate, o-tolyl (meth) acrylate, m-tolyl (meth) acrylate, p- Tolyl (meth) acrylate, 2,3-xylyl (meth) acrylate, 2,4-xylyl (meth) acrylate, 2,5-xylyl (meth) acrylate, 2,6-xylyl (meth) acrylate, 3,4- Examples include xylyl (meth) acrylate, 3,5-xylyl (meth) acrylate, 1-naphthyl (meth) acrylate, 2-naphthyl (meth) acrylate, binaphthyl (meth) acrylate, anthryl (meth) acrylate, and the like. These (meth) acrylates may be used alone or in combination of two or more.

  Examples of the method for polymerizing the monomer represented by the formula (3) include a bulk polymerization method, a solution polymerization method, an emulsion polymerization method, and a suspension polymerization method. By polymerizing the monomer represented by the formula (3), an acrylic resin having a repeating unit represented by the formula (2) can be obtained. By imidizing this with an imidizing agent, the formula (3) An acrylic resin having a repeating unit represented by 1) and a repeating unit represented by formula (2) is obtained.

  As the polymerization initiator used in the polymerization, known polymerization initiators can be used. For example, 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-amidinopropane) · 2 Water-soluble azo compounds such as hydrochloride, 4,4′-azobis (4-cyanopentanoic acid); persulfates such as potassium persulfate; hydrogen peroxide, peracetic acid, benzoyl peroxide, di-t-butyl peroxide A peroxide or the like may be used. These may use only 1 type and may use 2 or more types together. It is preferable that the usage-amount of a polymerization initiator shall be 0.01-1 mass part with respect to 100 mass parts of monomers, for example.

  Examples of the imidizing agent include cycloalkylamines having 3 to 12 carbon atoms such as cyclohexylamine; arylamines having 6 to 10 carbon atoms such as aniline, benzylamine, toluidine, and trichloroaniline. Etc. These imidizing agents may be used alone or in combination of two or more. As the imidizing agent, cyclohexylamine, aniline and toluidine are preferable, and aniline is more preferable from the viewpoint of obtaining a base film having excellent heat resistance and low birefringence.

  The amount of the imidizing agent varies depending on the content of the repeating unit represented by the formula (1) and the content of the repeating unit represented by the formula (2) in the acrylic resin to be obtained. I can't. Therefore, the amount of the imidizing agent is preferably adjusted so that the repeating unit represented by the formula (1) and the repeating unit represented by the formula (2) are contained in the acrylic resin at a predetermined content rate. . In other words, the content of the repeating unit represented by the formula (1) and the repeating unit represented by the formula (2) in the acrylic resin can be easily adjusted by adjusting the amount of the imidizing agent. Can do. The amount of the imidizing agent may be adjusted in the range of 5 to 100 parts by mass, for example, in the range of 10 to 70 parts by mass with respect to 100 parts by mass of the acrylic resin used for the imidization reaction. preferable.

  The imidization of the acrylic resin having a repeating unit represented by the formula (2) may be via a glutaric anhydride structure. For example, a glutarimide resin can be obtained by imidizing polymethyl methacrylate (PMMA) or the like with a primary amine, and it is known that this imidization passes through a glutaric anhydride structure. In order to produce an acrylic resin having a large content of glutarimide structure, it is important to efficiently produce a glutaric anhydride structure. An anhydrous acrylic resin having a repeating unit represented by formula (2) In order to promote the reaction of glutaroxidation (cyclization reaction to a glutaric anhydride structure), it is effective to carry out the reaction under high temperature and reduced pressure conditions. As a method for performing the reaction under such conditions, a method using an extruder or the like is effective.

  A catalyst may be used in the cyclization reaction to a glutaric anhydride structure. As the catalyst for promoting the reaction, at least one selected from the group consisting of acids, bases and salts thereof can be used. Kinds of acids, bases and salts thereof are not particularly limited.

  Examples of the acid include hydrochloric acid, sulfuric acid, p-toluenesulfonic acid, phosphoric acid, phosphorous acid, phenylphosphonic acid, methyl phosphate, and the like. Examples of the base include metal hydroxides, amines, imines, alkali metal derivatives, alkoxides, ammonium hydroxide salts and the like. Examples of the acid and base salts include metal acetates, metal stearates, metal carbonates, and the like. Among these catalysts, a compound having an alkali metal is preferable because an excellent reaction promoting effect is exhibited even in a small amount. Examples of the compound having an alkali metal include alkali metal hydroxides such as lithium hydroxide, sodium hydroxide and potassium hydroxide, sodium methoxide, sodium ethoxide, sodium phenoxide, potassium methoxide, potassium ethoxide and potassium phenoxide. And alkali metal alkoxide compounds such as lithium acetate, sodium acetate, potassium acetate, and organic carboxylic acid alkali metal salts such as sodium stearate. Among these compounds having an alkali metal, sodium hydroxide, sodium methoxide, lithium acetate and sodium acetate are preferable, and sodium methoxide and lithium acetate are more preferable.

  The amount of the catalyst is not particularly limited, but it is preferably used within the range where the acrylic resin is not adversely affected such as coloring and the transparency of the acrylic resin is not lowered. The amount of the catalyst is preferably about 0.01 to 1 part by mass with respect to 100 parts by mass of the acrylic resin to be subjected to anhydrous glutar oxidation, for example.

  In the case of imidizing an acrylic resin having a repeating unit represented by the formula (2) via a glutaric anhydride structure, the resulting glutaric anhydride resin (resin having a glutaric anhydride structure) is isolated, By imidizing the obtained glutaric anhydride resin, a glutarimide structure can be efficiently generated. This method is particularly effective when, for example, aniline having a low nucleophilicity compared to alkylamine such as methylamine is used as an imidizing agent.

  As a method of performing an imidation reaction of an acrylic resin having a repeating unit represented by the formula (2) (hereinafter sometimes referred to as “raw material acrylic resin”) with an imidizing agent, a known method may be used. For example, (1) The raw material acrylic resin is dissolved in a solvent inert to imidization, an imidizing agent is added to the obtained raw material acrylic resin solution, and the raw material acrylic resin and the imidizing agent are added. (2) Method of adding an imidizing agent to a raw material acrylic resin in a molten state using an extruder or the like, and reacting the raw material acrylic resin and the imidizing agent (melting) Kneading method).

  A batch type reaction vessel (pressure vessel) can be used for the batch type reaction method. The batch-type reaction vessel (pressure vessel) preferably has a structure in which a raw material acrylic resin dissolved in a solvent can be heated and stirred, and an imidizing agent can be added. Since the viscosity of the solution may increase as the process proceeds, it is more preferable that the stirring efficiency is excellent. Examples of the batch type reaction tank (pressure vessel) include a Max Blend (registered trademark) stirring tank manufactured by Sumitomo Heavy Industries, Ltd.

  In the batch reaction method, examples of the solvent inert to imidization include aliphatic alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, and isobutanol; benzene, toluene, xylene, chlorobenzene, Aromatic compounds such as chlorotoluene; ether compounds. These solvents may use only 1 type and may use 2 or more types together. Among these solvents, toluene and a mixed solvent of toluene and methanol are preferable.

  In the batch reaction method, the reaction temperature when reacting the raw acrylic resin and the imidizing agent is such that the raw acrylic resin is efficiently imidized with the imidizing agent, and the raw acrylic resin due to excessive heat history 160 degreeC or more is preferable from the point which suppresses decomposition | disassembly, coloring, etc., 180 degreeC or more is more preferable, 200 degreeC or more is more preferable, 400 degreeC or less is preferable, 350 degreeC or less is more preferable, 300 degreeC or less is more preferable. .

  In the melt-kneading method, an extruder can be used. Examples of the extruder include a single screw extruder, a twin screw extruder, and a multi-screw extruder. Among these extruders, a twin screw extruder is preferable because the raw acrylic resin and the imidizing agent can be mixed efficiently. Examples of the twin screw extruder include, for example, a non-meshing type co-rotating twin screw extruder, a meshing type co-rotating twin screw extruder, a non-meshing different direction rotating twin screw extruder, and a meshing type. A different direction rotation type twin screw extruder etc. are mentioned. These extruders may be used singly or two or more may be connected in series. Among the twin screw extruders, the meshing type co-rotating twin screw extruder is preferable because it can rotate at a high speed and can efficiently mix the raw acrylic resin and the imidizing agent. The extruder is preferably provided with a vent that can be depressurized to atmospheric pressure or lower in order to remove unreacted imidizing agent and by-products. The number of vents may be only one or plural.

  In the melt-kneading method, the raw material acrylic resin is imidized by, for example, charging the raw material acrylic resin from the raw material charging part of the extruder, melting the raw material acrylic resin, and filling the cylinder, and then imidizing agent. Can be injected into the extruder with an addition pump.

  In the melt-kneading method, the temperature of the reaction zone (resin temperature) in the extruder is 180 ° C. or higher from the viewpoint of efficiently progressing the imidization reaction of the raw acrylic resin and improving the chemical resistance and heat resistance. Preferably, 220 ° C. or higher is more preferable, and from the viewpoint of suppressing the decomposition of the raw acrylic resin and improving the bending resistance of the base film, 380 ° C. or lower is preferable, 350 ° C. or lower is more preferable, and 300 ° C. or lower is preferable. Further preferred. In addition, the reaction zone in an extruder means the area | region between the injection position of an imidizing agent and the resin discharge port (die part) in the cylinder of an extruder.

  In the melt-kneading method, imidization of the raw acrylic resin can be promoted by increasing the reaction time of the raw acrylic resin and the imidizing agent in the reaction zone in the extruder. The time required for imidization of the acrylic resin in the reaction zone in the extruder is preferably 10 seconds or longer, more preferably 30 seconds or longer from the viewpoint of sufficiently imidating the raw acrylic resin. From the viewpoint of improving the solubility of the imidizing agent, the pressure of the acrylic resin in the extruder is preferably atmospheric pressure or higher, more preferably 1 MPa or higher, and 50 MPa or lower in consideration of the pressure resistance of the extruder. It is preferable that it is 30 MPa or less. In the present specification, the pressure value is expressed in absolute pressure.

  When the acrylic resin is imidized by the melt-kneading method, instead of the extruder, for example, a horizontal biaxial reactor (manufactured by Sumitomo Heavy Industries, Ltd., trade name: Vivolac), vertical concentric biaxial stirring tank ( A reactor capable of dealing with a high viscosity such as a product name: Super Blend manufactured by Sumitomo Heavy Industries, Ltd. can also be used.

  When the raw acrylic resin is imidized with an imidizing agent, a carboxyl group or an acid anhydride group may be by-produced. Depending on the conditions for imidization, a large amount of carboxyl groups or acid anhydride groups may remain in the acrylic resin. When the carboxyl group or the acid anhydride group remains in the acrylic resin, the viscosity of the acrylic resin increases, and thus, for example, there is a possibility that the molding processability when filming or the like is lowered. Moreover, under wet heat conditions, hydrolysis of the acid anhydride group proceeds, and the durability of the resin and film may be reduced. Therefore, it is preferable to convert the carboxyl group and acid anhydride group contained in the imidized acrylic resin into an ester. Examples of the method for converting the carboxyl group and acid anhydride group contained in the imidized acrylic resin into an ester include a method for converting into an ester described in US Pat. No. 4,727,117.

  As a method of esterifying an acrylic resin with an esterifying agent, for example, (1) Imidation in a solvent inert to esterification is similar to the method of imidizing a raw acrylic resin with an imidizing agent. A method in which an acrylic resin is dissolved, an esterifying agent is added to the resulting acrylic resin solution, and the acrylic resin and the esterifying agent are reacted (batch type reaction method), (2) using an extruder, etc. A method of adding an esterifying agent to the molten acrylic resin and reacting the acrylic resin with the esterifying agent (melt kneading method) or the like can be employed.

  Examples of the esterifying agent include dimethyl carbonate, 2,2-dimethoxypropane, dimethyl sulfoxide, triethyl orthoformate, trimethyl orthoacetate, trimethyl orthoformate, diphenyl carbonate, dimethyl sulfate, methyl toluene sulfonate, methyl trifluoromethyl sulfonate. , Methyl acetate, methanol, ethanol, methyl isocyanate, p-chlorophenyl isocyanate, dimethylcarbodiimide, dimethyl-tert-butylsilyl chloride, isopropenyl acetate, dimethylurea, tetramethylammonium hydroxide, dimethyldiethoxysilane, tetra-N-butoxy Silane, dimethyl (trimethylsilane) phosphite, trimethyl phosphite, Trimethyl phosphate, tricresyl phosphate, diazomethane, ethylene oxide, propylene oxide, cyclohexene oxide, 2-ethylhexyl glycidyl ether, phenyl glycidyl ether, benzyl glycidyl ether. These esterifying agents may be used alone or in combination of two or more. Among these esterifying agents, dimethyl carbonate is preferable from the viewpoint of reducing cost and preventing adverse effects such as coloring on the acrylic resin. The amount of the esterifying agent is not particularly limited, but is usually preferably 0 to 32 parts by mass, and more preferably 0 to 16 parts by mass with respect to 100 parts by mass of the raw acrylic resin.

  The esterifying agent may be used in combination with a catalyst. Examples of the catalyst include aliphatic tertiary amines such as trimethylamine, triethylamine, and tributylamine, and base catalysts such as diazabicycloundecene and diazabicyclononene. These catalysts may use only 1 type and may use 2 or more types together. Among these catalysts, diazabicycloundecene is preferable from the viewpoint of reducing cost and preventing adverse effects such as coloring on the acrylic resin. The amount of the catalyst is not particularly limited, but is usually preferably 0 to 10 parts by mass, more preferably 0 to 5 parts by mass, and still more preferably 0 to 2 parts by mass with respect to 100 parts by mass of the raw acrylic resin. .

[1-3. Structure and forming method of base film]
In the present invention, the base film used for the transparent conductive film has a cyclic structure in the main chain and contains an acrylic resin having a glass transition temperature of 140 ° C. or higher. It is preferable to contain an acrylic resin as a main component. Therefore, the content of the acrylic resin in the base film is preferably 50% by mass or more, more preferably 70% by mass or more, still more preferably 85% by mass or more, and even more preferably 95% by mass or more. . The base film may be substantially composed only of an acrylic resin having a ring structure in the main chain and having a glass transition temperature of 140 ° C. or higher. Even when the acrylic resin has a repeating unit represented by the formula (1) and a repeating unit represented by the formula (2), it is preferably contained in the base film with such a content.

  The base film may contain a polymer other than an acrylic resin having a ring structure in the main chain. Examples of polymers other than acrylic resins having a ring structure in the main chain include olefin polymers such as polyethylene, polypropylene, ethylene-propylene copolymer, poly (4-methyl-1-pentene); polyvinyl chloride, Vinyl halide polymers such as polyvinylidene chloride and polyvinyl chloride; acrylic polymers such as polymethyl methacrylate; polystyrene, styrene-methyl methacrylate copolymer, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene block Styrenic polymers such as copolymers; Polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; Cellulose such as cellulose triacetate, cellulose acetate propionate, and cellulose acetate butyrate Acylate; polyamide such as nylon 6, nylon 66, nylon 610; polyacetal; polycarbonate; polyphenylene oxide; polyphenylene sulfide; polyetheretherketone; polysulfone; polyethersulfone; polyoxybenzylene; polyamidoimide; And rubber polymers such as ABS resin and ASA resin.

  The base film may contain various additives. Examples of additives include antioxidants such as hindered phenol antioxidants, phosphorus antioxidants, sulfur antioxidants; stabilization of light stabilizers, weather stabilizers, heat stabilizers, etc. Agents: Reinforcing materials such as glass fibers and carbon fibers; near infrared absorbers; flame retardants such as tris (dibromopropyl) phosphate, triallyl phosphate, antimony oxide; anionic surfactants, cationic surfactants, nonions Antistatic agents such as surfactants; colorants such as inorganic pigments, organic pigments and dyes; fillers such as organic fillers and inorganic fillers; resin modifiers; plasticizers; The content of these additives in the base film is preferably 0 to 5% by mass, more preferably 0 to 2% by mass, and still more preferably 0 to 0.5% by mass.

  The base film can be manufactured using an acrylic resin, for example, by a melt extrusion molding method such as a T-die method or an inflation method, a cast molding method, or a press molding method. When manufacturing a base film by a melt extrusion method, a single screw extruder, a twin screw extruder, etc. can be used, for example.

  The base film is preferably uniaxially stretched or biaxially stretched, and more preferably biaxially stretched from the viewpoint of increasing mechanical strength. Examples of the method of biaxially stretching the base film include a sequential biaxial stretching method and a simultaneous biaxial stretching method.

  The stretching temperature when stretching the base film is from the temperature lower by 20 ° C. than the glass transition temperature of the resin composition to be stretched from the viewpoint of stretching the base film without breaking and sufficiently molecular orientation. It is preferably a temperature range up to a temperature that is 50 ° C. higher than the glass transition temperature, more preferably from a temperature that is 10 ° C. lower than the glass transition temperature of the resin composition subjected to stretching to a temperature that is 30 ° C. higher than the glass transition temperature. Temperature range.

  The stretching ratio of the base film is preferably about 1.5 to 3 times from the viewpoint of increasing mechanical strength in both the longitudinal direction and the transverse direction perpendicular to the longitudinal direction. More preferably, it is about 5 to 2.5 times.

  The dimensional change rate of the stretched base film is preferably 1.0% or less from the viewpoint of improving the durability of the film subjected to the secondary processing to the transparent conductive film, and is 0.7% The following is more preferable, 0.5% or less is more preferable, and 0.2% or less is particularly preferable.

  The thickness of the base film is preferably 20 μm or more, more preferably 30 μm or more, further preferably 40 μm or more, more preferably 400 μm or less, more preferably 350 μm or less, and more preferably 300 μm or less in consideration of application to a transparent conductive film. Is more preferable. The thickness of the base film is measured, for example, using a digimatic micrometer (manufactured by Mitutoyo Corporation).

The in-plane retardation Re of the base film is preferably 20 nm or less, more preferably 10 nm or less, and even more preferably 5 nm or less, from the viewpoint of suppressing the anisotropy of the refractive index of the base film and reducing the birefringence. 3 nm or less is particularly preferable. In addition, the absolute value of the thickness direction retardation Rth of the substrate film is 20 nm or less from the viewpoint of suppressing the birefringence by suppressing the anisotropy of the refractive index of the substrate film, similarly to the in-plane retardation Re. Is preferably 10 nm or less, more preferably 5 nm or less, and particularly preferably 3 nm or less. For example, the absolute value of the thickness direction retardation Rth of the base film after biaxial stretching is controlled by controlling the absolute value of the stress optical coefficient (Cr) described above to 0.3 × 10 ⁻⁹ Pa ⁻¹ or less. The value can be 20 nm or less.

  The in-plane retardation Re and the thickness direction retardation Rth of the base film were measured using a retardation film / optical material inspection apparatus (manufactured by Otsuka Electronics Co., Ltd., product number: RETS-100), and with an incident angle of 40 nm. Obtained by measuring under the condition of °. The in-plane retardation Re of the base film is expressed by the formula: Re = (nx−ny) × d (where nx is the slow axis direction with respect to light having a wavelength of 590 nm (the maximum refractive index in the plane of the base film) Ny is calculated based on the fast axis direction (direction perpendicular to nx in the plane of the base film), and d is the thickness (nm) of the base film). . The thickness direction phase difference Rth is expressed by the formula: Rth = {(nx + ny) / 2−nz} × d (where nx is the refractive index in the slow axis direction with respect to light having a wavelength of 590 nm, and ny is in the fast axis direction) Nz is the refractive index in the thickness direction of the film, and d is the thickness (nm) of the film).

The absolute value of the photoelastic coefficient of the base film is preferably 10 × 10 ⁻¹² Pa ⁻¹ or less, preferably 6 × 10 ⁻¹² Pa ⁻ from the viewpoint of suppressing light leakage, particularly light leakage in a high temperature and high humidity environment. ¹ or less is more preferable. In addition, the photoelastic coefficient of a base film is calculated | required according to the following method. That is, the sample was cut into 20 mm × 50 mm with the stretching direction of the base film as the long side to prepare a sample, and this sample was attached to a photoelasticity measurement unit of an ellipsometer (manufactured by JASCO Corporation, product number: M-150) and stretched. Birefringence is measured at three points while applying a stress load of 5 to 25 N in parallel to the direction, and the inclination of the birefringence with respect to the stress is obtained as a photoelastic coefficient using light having a wavelength of 590 nm.

The linear expansion coefficient in the temperature range of 60 to 100 ° C. of the base film is preferably 80 × 10 ⁻⁶ K ⁻¹ or less, and 70 × 10 ⁻⁶ K ⁻¹ or less, from the viewpoint of suppressing dimensional changes in a high temperature environment. Is more preferable. The linear expansion coefficient of the base film at 60 to 100 ° C. was measured from 60 ° C. to 100 at a measurement load of 5 g and a heating rate of 5 ° C./min using a thermomechanical measuring device (manufactured by Shimadzu Corporation, product number: TMA-60). Calculated as the slope when the temperature is raised to ° C. The sample for measurement is prepared by cutting the base film into a size of 5 mm × 20 mm with the stretching direction as the long side, pretreating it at 60 ° C. for 15 hours, and then cooling to room temperature. .

  The water absorption rate of the base film is preferably 3.0% or less, more preferably 2.5% or less, and further preferably 2.0% or less, from the viewpoint of improving the molding processability to the transparent conductive film. preferable. The water absorption rate of the base film is determined by the following method. That is, using a manual heating press machine (IMC-180C, manufactured by Imoto Seisakusho Co., Ltd.), resin pellets were melt-pressed at a pressure of 20 MPa at a temperature of 250 ° C. for 2 minutes, and an unstretched film having a thickness of 200 μm was formed. The prepared and obtained unstretched film was dried at 80 ° C. for 24 hours, and then its mass X was measured. Next, the unstretched film obtained above is absorbed in water by storing it in a thermostatic bath at 85 ° C. and a relative humidity of 85%. After 250 hours, the unstretched film is taken out of the thermostat, and the mass Y of the unstretched film after water absorption is taking measurement. From the measured values of mass X and Y, the water absorption is determined based on the formula: {(Y−X) / X} × 100.

[2. (Primer layer)
The primer layer is provided on at least one side of the base film, and acts to enhance the adhesion between the base film and the hard coat layer. Accordingly, the primer layer is provided between the base film and the hard coat layer so as to be in contact with each of the base film and the hard coat layer. The primer layer is provided not on the surface of the base film in the thickness direction of the base film but on the surface determined by the side in the longitudinal direction and the side in the width direction of the base film, that is, the front surface and / or the back surface. It is done.

  The thickness of the primer layer is not particularly limited and varies depending on the thickness of the substrate film. For example, it is preferably 1 nm or more, more preferably 10 nm or more, further preferably 50 nm or more, and preferably 10 μm or less, more preferably 5 μm or less. Preferably, it is 1.5 μm or less. If the thickness of the primer layer is within such a range, it is easy to improve the adhesion between the base film and the hard coat layer, and it is possible to suppress the development of a phase difference due to the primer layer itself.

  The primer layer is preferably composed of a material having a refractive index close to that of the base film or the hard coat layer, and preferably contains a resin. As the resin contained in the primer layer, a known resin having easy adhesion or a composite resin thereof can be used. For example, a polyester resin, an acrylic resin, a urethane resin, a cellulose resin, a polyol resin, a polycarboxylic acid resin, or These composite resins are mentioned. These resins may be used alone or in combination of two or more. Preferably, the primer layer contains a resin selected from the group consisting of a polyester resin, an acrylic resin, a urethane resin, and a composite resin thereof, and at least one selected from a urethane resin, an acrylic resin, and a polyester-acrylic composite resin. More preferably it contains a seed.

  The formation method of the primer layer to a base film is not limited, What is necessary is just to follow a well-known method. The primer layer may be formed by applying an easy-adhesion composition containing an easily-adhesive resin to a base film, forming a coating film of the composition, and then drying the formed coating film. preferable.

[2-1. Polyester resin)
The polyester resin used as the resin having easy adhesion is preferably water dispersible. The polyester resin can be obtained by a known production method, for example, by subjecting a dicarboxylic acid component and a glycol component to a polycondensation reaction after esterification or transesterification, but the production method is not limited in any way. Absent. For example, a dicarboxylic acid component and a glycol component are esterified or transesterified at 130 to 200 ° C., and then subjected to a polycondensation reaction at 200 to 250 ° C. under reduced pressure conditions to obtain a polyester resin having easy adhesion. Can do. Examples of the catalyst used in this case include metal acetates such as zinc acetate and manganese acetate, metal oxides such as antimony oxide and germanium oxide, and titanium compounds.

  It is preferable that the dicarboxylic acid component which is a copolymerization component of the polyester resin essentially contains an ester-forming sulfonic acid alkali metal salt compound. Examples of the ester-forming alkali metal salt of sulfonic acid include alkali metal salts such as sulfoterephthalic acid, 5-sulfoisophthalic acid, 4-sulfoisophthalic acid, 4-sulfonaphthalenic acid-2,7-dicarboxylic acid (alkali sulfonic acid alkali). Metal salts), and ester-forming derivatives thereof, and the sodium salt of 5-sulfoisophthalic acid and ester-forming derivatives thereof are preferably used.

  The content of the ester-forming sulfonic acid alkali metal salt compound in the dicarboxylic acid component is preferably 6 mol% or more, more preferably 10 mol% or more, and preferably 20 mol% or less, preferably 18 mol% or less. More preferred. When the content of the ester-forming alkali metal sulfonate compound in the dicarboxylic acid component is less than 6 mol%, the dispersion time of the resin in water becomes long, and the solvent resistance of the primer layer may be insufficient. On the other hand, if the content exceeds 20 mol%, the water resistance of the primer layer tends to decrease.

  The dicarboxylic acid component may contain other dicarboxylic acid components that can be contained in addition to the ester-forming sulfonic acid alkali metal salt compound. Other dicarboxylic acid components include fragrances such as phthalic acid, terephthalic acid, dimethyl terephthalate, isophthalic acid, dimethyl isophthalate, 2,5-dimethylterephthalic acid, 2,6-naphthalenedicarboxylic acid, biphenyldicarboxylic acid, orthophthalic acid, etc. An aliphatic dicarboxylic acid such as succinic acid, adipic acid, azelaic acid, sebacic acid, and dodecane dicarboxylic acid; an alicyclic dicarboxylic acid such as cyclohexane dicarboxylic acid, and the like. Especially, as other dicarboxylic acid components, aromatic dicarboxylic acid is preferable, and terephthalic acid or isophthalic acid is more preferable. When aromatic dicarboxylic acid is used as the other dicarboxylic acid component, the affinity with the base film or the hard coat layer can be increased by the aromatic nucleus of the aromatic dicarboxylic acid, and the effect of improving adhesion can be expected.

  Examples of the glycol component that is a copolymer component of the polyester resin include aliphatic glycols having 2 to 8 carbon atoms, alicyclic glycols having 6 to 12 carbon atoms, and aromatic glycols. Examples of the aliphatic glycol having 2 to 8 carbon atoms include ethylene glycol, 1,3-propanediol, 1,2-propylene glycol, neopentyl glycol, 1,4-butanediol, , 6-hexanediol, diethylene glycol, triethylene glycol and the like. Examples of the alicyclic glycol having 6 to 12 carbon atoms include 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,2-cyclohexanedimethanol and the like. Examples of the aromatic glycol include p-xylylene glycol. These glycols may use only 1 type and may use 2 or more types together.

  It is preferable that the glycol component essentially contains diethylene glycol. In this case, the content of diethylene glycol in the glycol component is preferably in the range of 20 to 80 mol%. When diethylene glycol is contained in such a content, the solvent resistance against organic solvents (for example, alcohols, aromatic solvents such as toluene and xylene) can be improved.

  The polyester resin preferably has a number average molecular weight of 2,000 or more, more preferably 2,500 or more, preferably 30,000 or less, and more preferably 25,000 or less. When the number average molecular weight of the polyester resin is 2,000 or more, the solvent resistance is easily improved, and when the number average molecular weight is 30,000 or less, the water dispersibility of the resin is increased and the handleability is improved.

  When making a polyester resin water-dispersible, it is preferable to use it uniformly dispersed in water containing water or an aqueous solvent at 50 to 90 ° C. with heating and stirring. In addition, since the water dispersion obtained in this way cannot obtain a uniform dispersion when the solid content concentration becomes high, the polyester solid content concentration in the water dispersion is preferably 30% by mass or less. Examples of the aqueous solvent include lower alcohols such as methanol, ethanol, normal propanol, and isopropanol; polyhydric alcohols such as ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, and glycerin; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, Examples include propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol acetate, diethylene glycol monomethyl ether, and dipropylene glycol monomethyl ether.

  The polyester resin preferably has a carboxyl group. By having a carboxyl group, the adhesion to the base film and the hard coat layer is improved. This effect is particularly remarkable in a high temperature / high humidity environment. The polyester resin having a carboxyl group may be produced by a known production technique. The polyester resin having a carboxyl group may be, for example, a condensation reaction using a trivalent or higher polyvalent carboxylic acid or an ester-forming derivative thereof (hereinafter collectively referred to as “a trivalent or higher polyvalent carboxylic acid or the like”). By carrying out the polycondensation reaction, a carboxyl group resulting from a trivalent or higher polyvalent carboxylic acid or the like remains in the resin skeleton. Examples of the trivalent or higher polyvalent carboxylic acid include hemimellitic acid, trimellitic acid, trimedic acid, merophanic acid, pyromellitic acid, benzenepentacarboxylic acid, meritic acid, and cyclopropane-1,2,3-tricarboxylic acid. Examples include acids, polyvalent carboxylic acids such as cyclopentane-1,2,3,4-tetracarboxylic acid and ethanetetracarboxylic acid, and ester-forming derivatives thereof. Among these, especially when trimellitic anhydride, pyromellitic anhydride, and ester-forming derivatives thereof are used, the three-dimensional crosslinking of the polyester resin is sufficiently suppressed, and the carboxyl group can be effectively left in the polyester resin. it can.

[2-2. acrylic resin〕
The acrylic resin used as the resin having easy adhesion is preferably formed of an aqueous (meth) acrylic resin dispersion. The aqueous (meth) acrylic resin dispersion is typically obtained by emulsion polymerization of a monomer composition using an emulsifier.

  Examples of the monomer contained in the monomer composition include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4 A monomer having a hydroxyl group such as hydroxybutyl (meth) acrylate; cyclohexyl (meth) acrylate, methylcyclohexyl (meth) acrylate, tert-butylcyclohexyl (meth) acrylate, cyclooctyl (meth) acrylate, cyclododecyl (meth) acrylate, Isobornyl methacrylate, isobornyl acrylate, dicyclopentanyl methacrylate, dicyclopentanyl acrylate, 4-methylolcyclohexylmethyl acrylate, 4- Monomers having a cycloalkyl group such as tilcyclohexylmethyl (meth) acrylate and cyclohexylmethyl (meth) acrylate; glycidyl (meth) acrylate, α-methylglycidyl acrylate, glycidyl allyl ether, oxocyclohexylmethyl (meth) acrylate, 3, 4 -Monomers having an epoxy group such as epoxy cyclohexyl methyl acrylate, α-methyl glycidyl methacrylate, and 3,4-epoxy cyclohexyl methyl methacrylate. Examples of other monomers include (meth) acrylic acid esters such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, and (meth) acrylic acid-2-ethylhexyl; (Meth) acrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid, citraconic acid, maleic anhydride, monomethyl maleate, monobutyl maleate, monomethyl itaconate, monobutyl itaconate, vinylbenzoic acid, monohydroxyethyl oxalate Monomers having a carboxyl group such as (meth) acrylate, dimethyl maleate, diethyl maleate, dibutyl maleate, dimethyl fumarate, diethyl fumarate, dibutyl fumarate; (meth) acryloylaziridine, (meth) acrylic acid 2-azi Aziri such as lysinylethyl A monomer having an nyl group; a monomer having an oxazoline group such as 2-isopropenyl-2-oxazoline and 2-vinyl-2-oxazoline; (meth) acrylamide, N-monoethyl (meth) acrylamide, N-monomethyl (meth) acrylamide, Acrylamide derivatives such as N, N-dimethyl (meth) acrylamide, Nn-propyl (meth) acrylamide, N-isopropyl (meth) acrylamide, Nn-butyl (meth) acrylamide; styrene, vinyltoluene, α- Styrene derivatives such as methylstyrene and chloromethylstyrene; monomers having a cyano group such as (meth) acrylonitrile; dimethylaminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylamide, vinylpyridine, vinylimidazo And vinyl pyrrolidone, polyalkylene glycol (meth) acrylate, (meth) acryloylmorpholine, and hydroxyalkyl (meth) acrylamide.

  Any appropriate emulsifier may be used as the emulsifier. For example, an anionic surfactant, a nonionic surfactant, a cationic surfactant, an amphoteric surfactant, a polymer surfactant, and 1 in a molecule. Examples thereof include polymerizable surfactants having at least one polymerizable carbon-carbon unsaturated bond. These may use only 1 type and may use 2 or more types together.

  Examples of the anionic surfactant used as an emulsifier include alkali metal alkyl sulfates such as sodium dodecyl sulfate and potassium dodecyl sulfate; ammonium alkyl sulfates such as ammonium dodecyl sulfate; sodium dodecyl polyglycol ether sulfate and sodium sulfosinoate Alkali metal salts of sulfonated paraffins; alkyl sulfonates such as ammonium salts of sulfonated paraffins; fatty acid salts such as sodium laurate, triethanolamine oleate, triethanolamine abiate; sodium dodecylbenzene sulfonate, alkali phenol hydroxyethylene Alkyl aryl sulfonates such as alkali metal sulfates; Kill naphthalenesulfonates, naphthalenesulfonic acid-formalin condensates, dialkyl sulfosuccinates, polyoxyethylene alkyl sulfates salts, polyoxyethylene alkylaryl sulfate salts.

  Nonionic surfactants used as emulsifiers include, for example, polyoxyethylene alkyl ether, polyoxyethylene alkyl aryl ether, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, fatty acid monoglycerides such as glycerol monolaurate, poly Examples thereof include oxyethyleneoxypropylene copolymers, condensation products of ethylene oxide and fatty acid amines, amides or acids.

  Examples of the cationic surfactant used as an emulsifier include alkyl pyridinyl chloride and alkyl ammonium chloride.

  Examples of the amphoteric surfactant used as an emulsifier include lauryl petaine, stearyl petaine, lauryl dimethylamine oxide, and the like.

  Examples of the polymer surfactant used as an emulsifier include polyvinyl alcohol, sodium poly (meth) acrylate, potassium poly (meth) acrylate, ammonium poly (meth) acrylate, polyhydroxyethyl (meth) acrylate, poly Hydroxypropyl (meth) acrylate, copolymers of two or more polymerizable monomers that are constituent units of these polymers or copolymers with other monomers, phase transfer catalysts for crown ethers, etc. Can be mentioned.

  Examples of the polymerizable surfactant used as an emulsifier include sodium propenyl-2-ethylhexylbenzenesulfosuccinate, sulfate of polyoxyethylene (meth) acrylate, polyoxyethylene alkylpropenyl ether sulfate ammonium salt, and (meth) acrylic. Anionic polymerizable surfactants such as phosphoric acid esters of acid polyoxyethylene esters; nonionic polymerizable surfactants such as polyoxyethylene alkylbenzene ether (meth) acrylic acid esters and polyoxyethylene alkyl ether (meth) acrylic acid esters Agents and the like.

  As a method of emulsion polymerization for obtaining an aqueous (meth) acrylic resin dispersion, a known method may be employed. For example, a monomer composition, an emulsifier, a polymerization initiator, and an aqueous medium are added at a time for polymerization. A method, a so-called monomer dropping method, a pre-emulsion method, or the like can be used. Further, the emulsion particles may be made into a heterophasic structure by performing multi-stage polymerization such as seed polymerization, core-shell polymerization, and power feed polymerization.

  What is necessary is just to set the compounding quantity (total compounding quantity) of an emulsifier suitably, for example, it is preferable to set it as 0.5-10 mass parts with respect to 100 mass parts of monomer compositions. As the aqueous medium for emulsion polymerization, water is usually used, and a hydrophilic solvent such as a lower alcohol or a ketone can be used in combination as necessary.

  As a polymerization initiator used for emulsion polymerization, a known polymerization initiator can be used. For example, 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-amidinopropane) / dihydrochloric acid Salts, water-soluble azo compounds such as 4,4′-azobis (4-cyanopentanoic acid); persulfates such as potassium persulfate; hydrogen peroxide, peracetic acid, benzoyl peroxide, di-t-butyl peroxide, etc. And the like. These may use only 1 type and may use 2 or more types together. It is preferable that the compounding quantity of a polymerization initiator shall be 0.01-1 mass part with respect to 100 mass parts of monomer compositions, for example.

  In the case of emulsion polymerization, a chain transfer agent may be used in order to accelerate the polymerization rate or when polymerization is performed at a low temperature. As the chain transfer agent, for example, a reducing agent such as sodium bisulfite, ferrous chloride, ascorbate, or longalite can be used. In the above emulsion polymerization, a chain transfer agent such as t-dodecyl mercaptan, n-octyl mercaptan, n-dodecyl mercaptan, mercaptoacetic acid, mercaptopropionic acid, 2-mercaptoethanol and the like can be used.

  What is necessary is just to set suitably the reaction temperature and reaction time at the time of performing emulsion polymerization. The reaction temperature is preferably 0 to 100 ° C, more preferably 50 to 90 ° C. The reaction time is preferably 1 hour to 15 hours.

  The aqueous (meth) acrylic resin dispersion is preferably neutralized with a neutralizing agent in order to improve the stability of the dispersion. The pH of the aqueous (meth) acrylic resin dispersion is preferably 5 to 10, more preferably 6 to 9.5, and even more preferably 7 to 9.5. If the pH is less than 5, the dispersion and mechanical stability of the dispersion may be lowered. When pH exceeds 10, there exists a possibility that there may be a problem in practicality, such as a fall of water resistance and generation | occurrence | production of an odor.

  Any appropriate neutralizing agent may be used as the neutralizing agent, for example, alkali metal compounds such as sodium hydroxide and potassium hydroxide; alkaline earth metal compounds such as calcium hydroxide and calcium carbonate; Ammonia: Water-soluble organic amines such as dimethylaminoethanol, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monopropylamine, dimethylpropylamine, monoethanolamine, diethanolamine, triethanolamine, ethylenediamine, diethylenetriamine, etc. Is mentioned. These neutralizing agents may be used alone or in combination of two or more. Among these, tertiary amines such as ammonia, dimethylaminoethanol, triethanolamine, and trimethylamine are preferably used, and more preferably low-boiling amines such as ammonia, dimethylaminoethanol, and trimethylamine. By using such a neutralizing agent, a primer layer having excellent water resistance can be obtained.

  The acrylic resin that can be contained in the primer layer preferably has a carboxyl group and / or an epoxy group. That is, the acrylic resin preferably has one or both of a carboxyl group and an epoxy group. If the acrylic resin contained in the primer layer has a carboxyl group and / or an epoxy group, the adhesion of the primer layer to the base film or hard coat layer can be improved. This effect is particularly remarkable in a high temperature / high humidity environment.

  An acrylic resin containing a carboxyl group or an epoxy group may be produced by a known method. The carboxyl group-containing acrylic resin can be obtained, for example, by polymerizing a monomer composition having a carboxyl group such as (meth) acrylic acid or maleic acid. The epoxy group-containing acrylic resin can be obtained by polymerizing a monomer composition having an epoxy group such as glycidyl (meth) acrylate and α-methylglycidyl acrylate. The acrylic resin containing both a carboxyl group and an epoxy group can be obtained by polymerizing a monomer composition containing both a monomer having a carboxyl group and a monomer having an epoxy group.

[2-3. Urethane resin)
The urethane resin used as a resin having easy adhesion can typically be obtained by reacting a polyisocyanate and a polyol. The urethane resin is preferably water-dispersible.

  Examples of polyisocyanates include tetramethylene diisocyanate, dodecamethylene diisocyanate, 1,4-butane diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, and lysine diisocyanate. Aliphatic diisocyanates such as 2-methylpentane-1,5-diisocyanate, 3-methylpentane-1,5-diisocyanate; isophorone diisocyanate, hydrogenated xylylene diisocyanate, 4,4′-cyclohexylmethane diisocyanate, 1,4- Cycloaliphatic diisocyanate, methylcyclohexylene diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, etc. Cyanate; tolylene diisocyanate, 2,2′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, 4,4′-diphenylmethane diisocyanate, 4,4′-diphenyldimethylmethane diisocyanate, 4,4′-dibenzyl diisocyanate, 1 , 5-naphthylene diisocyanate, xylylene diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate and other aromatic diisocyanates; dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, α, α, α, α-tetramethylxylylene An araliphatic diisocyanate such as range isocyanate can be used.

  As the polyol, any polyol having two or more hydroxyl groups in the molecule can be used. Examples of the polyol include polyacryl polyol, polyester polyol, polyether polyol and the like. These polyols may use only 1 type and may use 2 or more types together.

  Typically, the polyacryl polyol includes a copolymer of a (meth) acrylic acid ester monomer and a monomer having a hydroxyl group. As the (meth) acrylic acid ester monomer, for example, methyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, or the like can be used. Examples of the monomer having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, (Meth) acrylic acid hydroxyalkyl esters such as (meth) acrylic acid 4-hydroxybutyl and (meth) acrylic acid 2-hydroxypentyl; (meth) acrylic acid monoesters of polyhydric alcohols such as glycerin and trimethylolpropane; N -Methylol (meth) acrylamide etc. can be used.

  The polyacryl polyol may be a copolymer with further other monomers. The other monomer is not particularly limited as long as it can be copolymerized with a (meth) acrylic acid ester monomer and a monomer having a hydroxyl group. Examples of other monomers include unsaturated monocarboxylic acids such as (meth) acrylic acid; unsaturated dicarboxylic acids such as maleic acid and anhydrides and mono- or diesters thereof; unsaturated nitriles such as (meth) acrylonitrile Unsaturated amides such as (meth) acrylamide and N-methylol (meth) acrylamide; Vinyl esters such as vinyl acetate and vinyl propionate; Vinyl ethers such as methyl vinyl ether; α-olefins such as ethylene and propylene; Examples include halogenated α, β-unsaturated aliphatic monomers such as vinyl chloride and vinylidene chloride; α, β-unsaturated aromatic monomers such as styrene and α-methylstyrene.

  The polyester polyol can be obtained, for example, by a reaction between a polybasic acid component and a polyol component.

  Examples of the polybasic acid component include orthophthalic acid, isophthalic acid, terephthalic acid, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, biphenyldicarboxylic acid, tetrahydrophthalic acid and the like. Aromatic dicarboxylic acids: oxalic acid, succinic acid, malonic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, dodecanedicarboxylic acid, octadecanedicarboxylic acid, tartaric acid, alkylsuccinic acid Aliphatic dicarboxylic acids such as linolenic acid, maleic acid, fumaric acid, mesaconic acid, citraconic acid, itaconic acid; hexahydrophthalic acid, tetrahydrophthalic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, etc. The alicyclic dicarboxylic acid ; Or, it is possible to use their anhydrides, alkyl esters, reactive derivatives such as acid halides and the like.

  Examples of the polyol component include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, and 1,6-hexane. Diol, 1,8-octanediol, 1,10-decanediol, 1-methyl-1,3-butylene glycol, 2-methyl-1,3-butylene glycol, 1-methyl-1,4-pentylene glycol, 2-methyl-1,4-pentylene glycol, 1,2-dimethyl-neopentyl glycol, 2,3-dimethyl-neopentyl glycol, 1-methyl-1,5-pentylene glycol, 2-methyl-1, 5-pentylene glycol, 3-methyl-1,5-pentylene glycol, 1,2-dimethylbuty Glycol, 1,3-dimethylbutylene glycol, 2,3-dimethylbutylene glycol, 1,4-dimethylbutylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, polypropylene glycol, 1,4-cyclohexanedimethanol 1,4-cyclohexanediol, bisphenol A, bisphenol F, hydrogenated bisphenol A, hydrogenated bisphenol F, and the like can be used.

  The polyether polyol can be typically obtained 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, and trimethylolpropane. As the alkylene oxide, for example, ethylene oxide, propylene oxide, butylene oxide, styrene oxide, tetrahydrofuran or the like can be used.

  The urethane resin that can be contained in the primer layer preferably has a carboxyl group. If the urethane resin contained in the primer layer has a carboxyl group, the adhesion of the primer layer to the base film or hard coat layer can be improved. This effect is particularly remarkable in a high temperature / high humidity environment.

  The urethane resin having a carboxyl group can be obtained, for example, by reacting a chain extender having a free carboxyl group in addition to polyisocyanate and polyol. As a chain extender having a free carboxyl group, for example, dihydroxycarboxylic acid, dihydroxysuccinic acid and the like can be used. Examples of the dihydroxycarboxylic acid include dialkylolalkanoic acids such as dimethylolalkanoic acid (for example, dimethylolacetic acid, dimethylolbutanoic acid, dimethylolpropionic acid, dimethylolbutyric acid, dimethylolpentanoic acid).

  The acid value of the urethane resin is preferably 10 mgKOH / g or more, more preferably 20 mgKOH / g or more, preferably 50 mgKOH / g or less, more preferably 45 mgKOH / g or less. By adjusting the acid value of the urethane resin in this way, the adhesion of the primer layer to the base film or hard coat layer can be further enhanced.

  The urethane resin may be obtained by reaction with other polyols or other chain extenders in addition to the components described above. Examples of other polyols include sorbitol, 1,2,3,6-hexanetetraol, 1,4-sorbitan, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerin, and trimethylol. Examples include ethane, trimethylolpropane, pentaerythritol and other polyols having three or more hydroxyl groups. Examples of other chain extenders include ethylene glycol, diethylene glycol, triethylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, 1,6 -Glycols such as hexanediol and propylene glycol; aliphatic diamines such as ethylenediamine, propylenediamine, hexamethylenediamine, 1,4-butanediamine, and aminoethylethanolamine; isophoronediamine, 4,4'-dicyclohexylmethanediamine, etc. Alicyclic diamines; and aromatic diamines such as xylylenediamine and tolylenediamine.

  The urethane resin can be produced by applying a known method. For example, a one-shot method in which each component is reacted at a time, a multistage method in which the components are reacted stepwise, and the like may be employed. The urethane resin having a carboxyl group is preferably produced by a multistage method because the introduction of the carboxyl group is easy. The catalyst used for the production of the urethane resin is not particularly limited.

[2-4. Polyester-acrylic composite resin)
When a polyester-acrylic composite resin is used as the resin having easy adhesion, the polyester-acrylic composite resin may be formed from a mixture of a polyester resin and an acrylic resin, or a (meth) acrylic monomer is added to the polyester resin. You may form from resin which copolymerized. From the viewpoint of environmental regulations, when forming the primer layer, since the aqueous system is more advantageous than the solvent system, the polyester-acrylic composite resin is preferably water-dispersible, and in particular, the polyester resin is water-dispersible. More preferably.

  As the polyester resin forming the polyester-acrylic composite resin, those described above as the polyester resin used as the resin having easy adhesion can be used. As the acrylic resin forming the polyester-acrylic composite resin, those described above as the acrylic resin used as the resin having easy adhesion can be used.

  The compounding ratio of the polyester resin component and the acrylic resin component of the polyester-acrylic composite resin is not particularly limited, but the solid content mass ratio of the polyester resin / acrylic resin is preferably 10/90 or more, more preferably 20/80 or more, Moreover, 80/20 or less is preferable and 70/30 or less is more preferable.

  The polyester-acrylic composite resin preferably has an epoxy group. Specifically, the acrylic resin compounded with the polyester resin preferably has an epoxy group. When the polyester-acrylic composite resin has an epoxy group, the solvent resistance of the primer layer is improved, and the adhesion to the base film or the hard coat layer is improved.

  The epoxy group-containing acrylic resin is obtained by homopolymerizing an epoxy group-containing radical polymerizable unsaturated monomer, or an epoxy group-containing radical polymerizable unsaturated monomer and another radical polymerizable unsaturated monomer that can be copolymerized therewith. It can be obtained by copolymerization. The epoxy group-containing radically polymerizable unsaturated monomer is considered to improve water resistance and solvent resistance by advancing internal crosslinking of the epoxy group-containing acrylic resin. In particular, the solvent resistance to ketone solvents such as acetone and methyl ethyl ketone and ester solvents such as ethyl acetate and butyl acetate can be enhanced.

  Examples of the epoxy group-containing radical polymerizable unsaturated monomer include glycidyl ethers such as glycidyl acrylate, glycidyl methacrylate, and allyl glycidyl ether.

  Examples of the radical polymerizable unsaturated monomer that can be copolymerized with the epoxy group-containing radical polymerizable unsaturated monomer include vinyl ester, unsaturated carboxylic acid ester, unsaturated carboxylic acid amide, unsaturated nitrile, unsaturated carboxylic acid, and allyl. Examples include compounds, nitrogen-containing vinyl monomers, hydrocarbon vinyl monomers, and vinyl silane compounds.

  Examples of the vinyl ester include vinyl propionate, vinyl stearate, higher tertiary vinyl ester, vinyl chloride, vinyl bromide and the like.

  Examples of unsaturated carboxylic acid esters include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, butyl maleate, octyl maleate, and fumaric acid. Butyl, octyl fumarate, hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate, dimethylaminoethyl methacrylate, dimethylaminoethyl acrylate, ethylene glycol dimethacrylate, ethylene glycol diacrylic acid Examples thereof include esters, polyethylene glycol dimethacrylic acid esters, and polyethylene glycol diacrylic acid esters.

  Examples of the unsaturated carboxylic acid amide include acrylamide, methacrylamide, methylol acrylamide, butoxymethylol acrylamide and the like.

  Examples of unsaturated nitriles include acrylonitrile.

  Examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, maleic acid acidic ester, fumaric acid acidic ester, itaconic acid acidic ester, and the like.

  Examples of the allyl compound include allyl acetate, allyl methacrylate, allyl acrylate, diallyl itaconate, and the like.

  Examples of the nitrogen-containing vinyl monomer include vinyl pyridine and vinyl imidazole, and examples of the hydrocarbon vinyl monomer include ethylene, propylene, hexene, octene, styrene, vinyl toluene, and butadiene.

  Examples of the vinylsilane compound include dimethylvinylmethoxysilane, dimethylvinylethoxysilane, methylvinyldimethoxysilane, methylvinyldiethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyldimethoxysilane, and the like.

  The epoxy group-containing radically polymerizable unsaturated monomer is preferably contained in an amount of 10 to 100% by mass, more preferably 20 to 100% by mass, based on all monomers forming the acrylic resin. In addition, when the content of the epoxy group-containing radical polymerizable unsaturated monomer is less than 10% by mass, solvent resistance to alcohol can be obtained, but ketone solvents such as acetone and methyl ethyl ketone, esters such as ethyl acetate and butyl acetate, and the like. There is a risk that the solvent resistance to the system solvent will be insufficient.

  The polyester-acrylic composite resin preferably further has a carboxyl group in addition to the epoxy group. Specifically, it is preferable that the acrylic resin compounded with the polyester resin has a carboxyl group in addition to the epoxy group. The acrylic resin having a carboxyl group can be obtained by using an unsaturated carboxylic acid such as acrylic acid or methacrylic acid as the radical polymerizable unsaturated monomer. When an unsaturated carboxylic acid such as acrylic acid or methacrylic acid is used as the radical polymerizable unsaturated monomer, the solvent resistance of the primer layer is improved due to crosslinking with the epoxy group, and adhesion to the base film or hard coat layer is improved. The sex can be further improved.

  It is preferable that 5-20 mass% of unsaturated carboxylic acid monomers are contained in all the monomers which form an acrylic resin. When the content of the unsaturated carboxylic acid monomer is 5% by mass or more, the combined effect with the epoxy group can be enhanced. On the other hand, when the content of the unsaturated carboxylic acid monomer exceeds 20% by mass, the viscosity during polymerization becomes too high, or the liquid gels with time, and the storage stability tends to be lowered.

  The epoxy group-containing acrylic resin can be produced by a known method. For example, ion-exchanged water, a polymerization initiator, and a surfactant are charged into a reaction tank, while ion-exchanged water and a surfactant are charged into a dropping tank, and monomers are added to prepare an emulsion. An epoxy group-containing acrylic resin can be obtained by performing a reaction by dropping the solution onto the epoxy resin. At this time, the reaction temperature is preferably 60 to 100 ° C., and the reaction is preferably performed for 4 to 10 hours. The epoxy group-containing acrylic resin is not limited to the production method.

  As the surfactant used for emulsion polymerization, an anionic or nonionic reactive or non-reactive surfactant is preferably used. Examples of the reactive surfactant include anionic surfactants such as alkylallylsulfosuccinate, polyoxyethylene alkylpropenyl phenyl ether sulfate, polyoxyalkylene alkenyl ether sulfate, and (meth) acrylate sulfate; Nonionic surfactants such as polyoxyethylene alkylpropenyl phenyl ether, polyoxyalkylene alkenyl ether, (meth) acrylate sulfate and the like can be mentioned. Non-reactive surfactants include, for example, anionic interfaces such as alkyl sulfates, alkylbenzene sulfonates, alkyl sulfosuccinates, alkyl diphenyl ether disulfonates, polyoxyethylene alkyl sulfates, polyoxyethylene alkyl phosphates, etc. Activators: Nonionic surfactants such as polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene diphenyl ether, polyoxyethylene fatty acid ester, and the like. These surfactants may be used alone or in combination of two or more.

  As a polymerization initiator used for emulsion polymerization, a general radical polymerizable initiator (for example, a water-soluble peroxide such as potassium persulfate, ammonium persulfate, hydrogen peroxide; benzoyl peroxide, t-butyl hydroperoxide). Oil-soluble peroxides such as azo compounds such as azobisisobutyronitrile).

[2-5. Urethane-acrylic composite resin)
When the urethane-acrylic composite resin is used as the resin having easy adhesion, the urethane-acrylic composite resin is obtained by, for example, changing the polyester to urethane in the method for producing the polyester-acrylic composite resin described above, or As described above, it can be produced by using a polyacryl polyol at the time of producing a urethane resin.

[2-6. Polyester-urethane composite resin)
When a polyester-urethane composite resin is used as the resin having easy adhesion, the polyester-urethane composite resin can be produced by using a polyester polyol in the urethane resin production method described above, for example.

[2-7. Water-soluble resin)
The primer layer may contain a water-soluble resin. If the primer layer contains a water-soluble resin, the adhesion of the primer layer to the base film or hard coat layer can be enhanced.

  The kind of water-soluble resin is not particularly limited, and a known water-soluble resin or a composite resin thereof can be used. Examples of the water-soluble resin include polyvinyl alcohol, polyvinyl pyrrolidone, polyethylene glycol, polyacrylic acid and salts thereof, hydroxyethyl cellulose, carboxymethyl cellulose, and the like. Among these, polyvinyl alcohol or polyvinyl pyrrolidone is preferably used.

  The primer layer can be formed by applying an easy-adhesive composition containing an easily adhesive resin to the base film, but the water-soluble resin is applied to the base film by an easy-adhesive composition. What is necessary is just to make it contain in the composition for easy-bonding. The composition for easy adhesion may contain a water-soluble resin in advance or may be a mixture with a composition containing a water-soluble resin.

  The easy-adhesion composition containing a water-soluble resin can be obtained by mixing an easily-adhesive resin and a water-soluble resin, and the easy-adhesion composition not containing a water-soluble resin It can also be obtained by mixing with a composition containing a water-soluble resin. These compositions are preferably water-based compositions, more preferably a resin having easy adhesion and / or a dispersion of a water-soluble resin, and typically a resin having easy adhesion. An emulsion and / or an emulsion of a water-soluble resin. The emulsion of the easily adhesive resin and the water-soluble resin becomes a resin layer containing the easily adhesive resin and the water-soluble resin by drying.

  In the easy-adhesion composition, the compounding ratio of the easily-adhesive resin and the water-soluble resin is not particularly limited, but the solid content mass ratio of the easily-adhesive resin / water-soluble resin is preferably 10/90 or more. 20/80 or more is more preferable, 30/70 or more is more preferable, 100/0 or less is preferable, 90/10 or less is more preferable, and 80/20 or less is more preferable. By adjusting the blending ratio of the resin having easy adhesion and the water-soluble resin to such a range, the adhesion and water resistance of the primer layer can be enhanced.

[2-8. Fine particle component)
The primer layer may contain fine particles. If the primer layer contains fine particles, the blocking resistance can be improved.

  Any appropriate fine particles can be used as the fine particles, and water-dispersible fine particles are preferable. As the fine particles, either inorganic fine particles or organic fine particles can be used, and organic-inorganic composite fine particles may be used.

  Examples of the inorganic fine particles include inorganic oxides such as silica, titania, alumina, zirconia, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, calcium phosphate, and the like. Can be mentioned. Examples of the organic fine particles include silicone resins, fluorine resins, (meth) acrylic resins, and the like. Among these, silica is preferable. Silica is excellent in blocking inhibition ability and transparency, does not cause haze, and is not colored, so it hardly affects the optical properties of the transparent conductive film. Silica has excellent dispersibility and dispersion stability in the easy-adhesion composition, so that it is excellent in workability at the time of forming the primer layer, and also excellent in adhesion to the base film and the hard coat layer. It will be a thing.

  When the composition forming the primer layer (composition for easy adhesion) is water-based, the fine particles are preferably blended as an aqueous dispersion. For example, when silica is employed as the fine particles, colloidal silica can be used. Examples of colloidal silica include Quartron (registered trademark) PL series manufactured by Fuso Chemical Industries, Snowtex (registered trademark) series manufactured by Nissan Chemical Industries, Aerodisp (registered trademark) series and Aerosil (registered trademark) manufactured by Nippon Aerosil Co., Ltd. Trademark) series or the like can be used.

  The content of fine particles in the primer layer is preferably less than 10% by mass, more preferably less than 5% by mass, and still more preferably less than 2% by mass. When the content of the fine particles exceeds 10% by mass, the coating film strength of the primer layer may be lowered or the transparency may be impaired. The lower limit of the content rate of the fine particles in the primer layer is preferably 0.1% by mass or more, more preferably 0.15% by mass or more, and more preferably 0.2% by mass or more from the viewpoint of expressing the effect of containing the fine particles in the primer layer. Is more preferable. The primer layer may not contain fine particles.

  In order to improve the adhesion between the base film and the hard coat layer, the particle diameter (average primary particle diameter) of the fine particles is preferably 1 nm or more, more preferably 10 nm or more, further preferably 20 nm or more, particularly preferably 30 nm or more. Moreover, 300 nm or less is preferable, 200 nm or less is more preferable, and 150 nm or less is more preferable. By using fine particles having such a particle size, the optical properties of the transparent conductive film are improved. In particular, as the average primary particle diameter is smaller than the visible light wavelength and smaller, the light scattering by the fine particles can be suppressed, so that the influence on the optical characteristics can be further suppressed. Further, by using fine particles having such a particle size, irregularities having an appropriate size are formed on the surface of the primer layer, whereby the surface friction force is reduced and the blocking resistance can be effectively enhanced.

  The fine particles are preferably as uniform in particle size as possible. In this respect, the particle size distribution index (d25 / d75) of the fine particles is preferably 1.0 or more, preferably 1.4 or less, and more preferably 1.2 or less.

  The average primary particle size and particle size distribution index of the fine particles can be determined by a laser diffraction / scattering type particle size distribution measuring apparatus (for example, Submicron Particle Sizer NICOM 380 manufactured by Particle Sizing Systems). Specifically, the equivalent spherical distribution of the fine particles dispersed in the medium is obtained by the measuring device. Next, in the obtained distribution, the particle diameter of particles with an integrated volume fraction of 50% accumulated from the large particle side is obtained, and this is used as the average primary particle diameter (d50) of the fine particles. Separately from this, the particle diameter (d25) of particles with an integrated volume fraction of 25% and the particle diameter (d75) of 75% of particles accumulated from the large particle side in the distribution are obtained, and the ratio (d25 / d75) Is the particle size distribution index of the fine particles. In addition, although a medium can be suitably selected according to the structure and capability of a particle size distribution apparatus, for example, water can be used, it is not restricted to a liquid.

[2-9. water〕
The easy adhesion composition is preferably an aqueous composition. Compared to organic solvent-based compositions, water-based compositions are less burdensome on the environment when forming the primer layer and are excellent in workability. The aqueous composition is, for example, a resin dispersion having easy adhesion. The dispersion is typically an emulsion of resin having easy adhesion. The emulsion of the resin having easy adhesion becomes a resin layer containing the resin having easy adhesion by drying. When the emulsion contains fine particles, the fine particles remain in the resin layer as they are.

  When the easy-adhesion composition is aqueous, it is preferable to use an organic solvent that is compatible with water when forming the resin constituting the primer layer. Examples of the organic solvent include ester solvents such as ethyl acetate, butyl acetate, and ethyl cellosolve acetate; ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; ether solvents such as dioxane, tetrahydrofuran, and propylene glycol monomethyl ether Is mentioned.

[2-10. Crosslinking agent]
It is preferable that the composition for easy adhesion contains a crosslinking agent. If the easy-adhesion composition contains a cross-linking agent, the adhesion of the primer layer is improved.

  The type of the crosslinking agent is not particularly limited. When the resin constituting the primer layer has a carboxyl group, the crosslinking agent is preferably a polymer having a group capable of reacting with the carboxyl group. Examples of the group capable of reacting with a carboxyl group are an organic amino group, an oxazoline group, an epoxy group, and a carbodiimide group, and an oxazoline group is preferable. The cross-linking agent having an oxazoline group has a long pot life at room temperature when mixed with the resin constituting the primer layer, and the cross-linking reaction proceeds by heating, so that workability is improved. The polymer is, for example, a (meth) acrylic polymer or a styrene / acrylic polymer, and a (meth) acrylic polymer is preferable. When the crosslinking agent is a (meth) acrylic polymer, the performance of the primer layer is further improved. In addition to this, the (meth) acrylic polymer is stably compatible with the water-based easy-adhesion composition and well crosslinks the resin constituting the primer layer.

  In the easy-adhesion composition, the content of the resin constituting the primer layer is preferably 1.5% by mass or more from the viewpoint of improving the coating property when the easy-adhesion composition is applied to the surface of the base film. 2 mass% or more is more preferable, 15 mass% or less is preferable, and 10 mass% is more preferable. When the composition for easy adhesion contains a crosslinking agent, the content of the crosslinking agent is preferably 1 part by mass or more and more preferably 3 parts by mass or more with respect to 100 parts by mass of the resin (solid content) constituting the primer layer. It is preferably 30 parts by mass or less, and more preferably 20 parts by mass or less. When the composition for easy adhesion contains fine particles, the content of the fine particles is preferably 0.3 parts by mass or more, and 0.5 parts by mass or more with respect to 100 parts by mass of the resin (solid content) constituting the primer layer. Is more preferable, 10 parts by mass or less is preferable, and 1 part by mass or less is more preferable.

[3. Hard coat layer)
The hard coat layer is provided on the base film via an adhesive layer for the purpose of improving the scratch resistance and durability of the transparent conductive film. By providing the hard coat layer, the base film can be prevented from being damaged during the formation of the transparent conductive layer, and the transparent conductive layer can be firmly provided on the hard coat layer.

  The hard coat layer preferably contains a resin. As the resin contained in the hard coat layer, those known in the art can be used. For example, polyfunctional acrylate is preferably used. The hard coat layer can be formed, for example, by applying a coating solution in which a polyfunctional acrylate and a photopolymerization initiator are dissolved or dispersed in an organic solvent on the primer layer, drying and photocuring. The polyfunctional acrylate is not particularly limited as long as it is a compound having 2 or more (preferably 3 or more) acryloyl groups in one molecule.

[4. Transparent conductive layer)
The transparent conductive layer is formed on the hard coat layer and is formed on the surface of the hard coat layer opposite to the primer layer. The transparent conductive layer may be provided in contact with the hard coat layer or may be provided via another layer. As the material constituting the transparent conductive layer, any material conventionally used as a conductive material in the field can be used. Specifically, an organic conductive compound; an organic conductive polymer; indium oxide; Metal oxides such as tin oxide, zinc oxide, indium-tin oxide (ITO), antimony-tin oxide (ATO), zinc-aluminum oxide, indium-zinc oxide (IZO); gold, silver, copper, Examples include metals such as palladium and aluminum. Among these, those containing zinc oxide or indium oxide are preferable, and those containing indium oxide are more preferable. Among these, indium-tin oxide is preferable because it has both high transparency and conductivity. That is, the transparent conductive layer is preferably an indium-tin oxide (ITO) layer.

  The thickness of the transparent conductive layer is preferably 0.001 μm or more, more preferably 0.005 μm or more, further preferably 0.01 μm or more from the viewpoint of ensuring conductivity, and 10 μm or less from the viewpoint of improving light transmittance. Is preferably 1 μm or less, and more preferably 0.5 μm or less.

  Examples of the method for forming the transparent conductive layer on the hard coat layer include thin film forming means such as sputtering, ion plating, and vacuum deposition. Among these, it is preferable to employ the sputtering method in terms of easy control of the film thickness and composition of the transparent conductive layer and excellent 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, facing target sputtering (FTS), unbalanced magnetron sputtering, ion beam sputtering, ECR (electron) (Cyclotron resonance) Sputtering and other beam methods. 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).

  As a sputtering gas for forming the transparent conductive layer by a sputtering method, a rare gas such as argon, helium, or neon can be used. Further, oxygen, nitrogen, or the like 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. If 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 can be easily obtained.

[5. Other layers]
In the transparent conductive film of the present invention, the primer layer, the hard coat layer, and the transparent conductive layer may be laminated in this order only on one side of the base film, and the primer layer and the hard coat layer are formed on both sides of the base film. The transparent conductive layer may be laminated in this order.

  When the primer layer, the hard coat layer, and the transparent conductive layer are laminated only on one side of the base film, another layer may be provided on the one side on the opposite side of the base film. Further, another layer may be provided on the transparent conductive layer. Other layers include, for example, an antistatic layer, an antiglare layer (non-glare) layer, an optical adjustment layer, a photocatalyst layer, an antifouling layer, an antireflection layer, a hard coat layer, an ultraviolet shielding layer, a heat ray shielding layer, an electromagnetic wave shielding layer, Gas barrier layer and the like.

  In the transparent conductive film, another layer may be provided between the hard coat layer and the transparent conductive layer. For example, an optical adjustment layer is preferably provided between the hard coat layer and the transparent conductive layer, whereby the transmittance or reflectance of incident light can be appropriately adjusted. As described in, for example, Japanese Patent Application Laid-Open No. 2006-201450, the optical adjustment layer is formed by alternately arranging a low refractive index layer having a relatively low refractive index and a high refractive index layer having a relatively high refractive index. It can be formed by laminating.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the scope of the present invention is not limited to these examples, and all modifications made without departing from the spirit of the present invention are described in the present invention. It is included in the technical scope of the invention.

(1) the fraction of imide units of the analytical method (1-1) imidization ratio acrylic resin, derived from the absorption derived from a carboxylic acid anhydride group in the vicinity of 1803cm ^-1, to the ester carbonyl group in the vicinity of 1720 cm ^-1 absorption And an intensity ratio with absorption derived from an imidecarbonyl group in the vicinity of 1680 cm ⁻¹ . Here, the imidization rate is a ratio of imide carbonyl groups in all carbonyl groups.

(1-2) Content of repeating unit represented by formula (2) In the acrylic resin, the content of the repeating unit represented by formula (2) is measured by an NMR measuring apparatus (manufactured by Varian, trade name: Unity). It is determined by measuring ¹ H-NMR spectrum using Plus400). Specifically, acrylic resin (mass: a) and 1,1,2,2-tetrachloroethane (molecular weight: 167.85, mass: b) as an internal standard are dissolved in heavy acetone, and the internal standard (5 .9 ppm, 2 protons) and the peak area ratio derived from the R ⁶ proton adjacent to the ester carbonyl group, that is, the peak area A derived from the R ⁶ proton adjacent to the ester carbonyl group and the internal standard proton From the ratio to the peak area B (peak area A / peak area B), the content of the repeating unit represented by the formula (2) is calculated.
For example, when R ^{4 of the} repeating unit represented by the formula (2) is a hydrogen atom, R ⁵ is a methyl group, and R ⁶ is a methyl group (the molecular weight of the repeating unit is 100.12), the formula ( The content (% by mass) of the repeating unit represented by 2) is expressed by the formula: [(peak area A / peak area B) × (2/3) × (b / 167.85) × (1 / 100.12). )] × (100 / a).

(1-3) Weight average molecular weight The weight average molecular weight of acrylic resin is calculated | required on condition of the following by gel permeation chromatography (GPC).
-System: manufactured by Tosoh Corporation, trade name: GPC system HLC-8220
-Developing solvent: Tetrahydrofuran (Wako Pure Chemical Industries, special grade)
-Solvent flow rate: 0.6 mL / min
-Standard sample: TSK standard polystyrene (trade name: PS-oligomer kit, manufactured by Tosoh Corporation)
-Measurement side column configuration: guard column (manufactured by Tosoh Corporation, trade name: TSK-GEL super HZM-M 6.0 × 150 in series, two manufactured by Tosoh Corporation, trade name: TSK-GEL super HZ-L 1 Use)
-Configuration of the reference side column: Reference column (product name: TSK-GEL SuperH-RC 6.0 × 150, two in series connection, manufactured by Tosoh Corporation)
-Column temperature: 40 ° C

(1-4) Stress optical coefficient (Cr)
The stress optical coefficient (Cr) of the acrylic resin is determined by the following method. First, an unstretched film is cut into a 60 mm × 20 mm rectangle, a weight is selected so as to have a stress of 1 N / mm ² or less, and the unstretched film is attached to the lower end of the unstretched film. This unstretched film is set in a constant temperature dryer (manufactured by ASONE, product number: DOV-450A) at a temperature 3 ° C. higher than the glass transition temperature of the acrylic resin at a chuck distance of 40 mm and held at that temperature for about 30 minutes. Then, after the stretching, the heating is stopped, and cooling is performed at a cooling rate of about 1 ° C./min until the temperature becomes 40 ° C. lower than the glass transition temperature of the acrylic resin. Then, the obtained stretched film is taken out from the constant temperature dryer, and the length and thickness of the stretched film and the weight of the weight are measured, and the in-plane retardation Re of the stretched film is measured. Further, the length and thickness of the stretched film and the weight of the weight were measured in the same manner as described above using four kinds of weights so that the stress was 1 N / mm ² or less. The in-plane phase difference Re is measured.

Based on the above results, based on the measurement method described in Polymer Science Society, “Frontier of Transparent Plastics (Polymer Frontier 21 Series)”, NTS, October 2006, pages 37-44. The stress optical coefficient (Cr) is calculated. Specifically, Δn (nx−ny) is plotted on the y-axis and σ is plotted on the x-axis, the slope of the straight line obtained by the least square method is obtained, and the value of the slope is defined as the stress optical coefficient (Cr). . In addition, nx represents the refractive index in the slow axis direction in the film plane (direction showing the maximum refractive index in the film plane), and ny represents the fast axis direction in the film plane (nx in the film plane). (Vertical direction) represents the refractive index, and σ represents the stress (N / m ² ) for stretching.

(1-5) Acid value The acid value of the acrylic resin is determined by the following method. Dissolve 0.15 g of sample (resin) in 24.94 g of methylene chloride, add 14.85 g of methanol, and stir for 3 hours. Thereafter, 2 drops of a 1% by weight phenolphthalein ethanol solution were added to this solution, while stirring, a 0.1N sodium hydroxide aqueous solution was added, and stirring was continued for 1 hour at room temperature. Let the usage-amount of sodium aqueous solution be A (mL). To this solution, 0.1N hydrochloric acid is added dropwise, and a drop amount B (mL) of 0.1N hydrochloric acid until the reddish purple color of the solution disappears is measured. Next, 2 drops of a 1% by weight phenolphthalein ethanol solution were added to a mixed solution of 24.94 g of methylene chloride and 14.85 g of methanol, and a 0.1N sodium hydroxide aqueous solution was added while stirring, followed by stirring at room temperature for 1 hour. The amount of 0.1N sodium hydroxide aqueous solution used at this time is C (mL). 0.1N hydrochloric acid is added dropwise to this solution, and a drop amount D (mL) of 0.1N hydrochloric acid until the reddish purple color of the solution disappears is measured. The ratio E (mmol / g) of the carboxyl group remaining in the resin is obtained by the following formula: E = 0.1 × {(A−B) − (C−D)} / 0.15.

(2) Production of constituent raw materials of transparent conductive film (2-1) Production example 1 (production of unstretched film A1)
In a reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introduction pipe, 79.4 parts by mass of methyl methacrylate, 20.6 parts by mass of methacrylic acid, 90.0 parts by mass of toluene as a polymerization solvent and 22. 5 parts by mass of a mixed solvent and 0.05 parts by mass of an antioxidant (trade name: ADK STAB 2112 manufactured by ADEKA) were charged, and the temperature was raised to 73 ° C. while passing nitrogen gas through the reaction vessel. At the point of time when reflux accompanying the temperature rise starts, dimethyl-2,2′-azobis (2-methylpropionate) (trade name: V-601, manufactured by Wako Pure Chemical Industries, Ltd.) as a polymerization initiator is 0.25 mass. And 0.35 parts by mass of the above dimethyl-2,2′-azobis (2-methylpropionate) in a mixed solvent of 7.3 parts by mass of toluene and 1.8 parts by mass of methanol. While the dissolved solution was dropped into the reaction vessel over 2 hours, solution polymerization was performed under reflux at about 71 to 76 ° C. After completion of the dropwise addition of dimethyl-2,2′-azobis (2-methylpropionate), the mixture was further aged for 4 hours. The content rate of the repeating unit derived from methacrylic acid in the acrylic resin contained in the obtained polymerization solution was 20.6% by mass. The weight average molecular weight of the acrylic resin was 110,000.

  Next, a solution obtained by dissolving 0.05 parts by mass of sodium methoxide, which is a catalyst for the cyclization condensation reaction (cyclization catalyst), in 5.0 parts by mass of methanol was added to the obtained polymerization solution over 20 minutes. The solution was dropped into a reaction vessel at about 65 to 70 ° C. to obtain a uniform polymerization solution. The polymerization solution thus obtained was subjected to a vent type screw twin screw extrusion with a barrel temperature of 300 ° C., a rotation speed of 238 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 2. Introduced into a machine (caliber: 15 mm, L / D: 45) at a processing rate of 576 g / h in terms of resin amount, devolatilized in this extruder, and extruded in a shaft residence time of about 2.8 minutes As a result, a transparent pellet P1 was obtained. The degree of vacuum is 0 hPa in a vacuum state. The weight average molecular weight of the acrylic resin in the pellet P1 was 100,000, and the glass transition temperature was 130 ° C.

Next, the pellet P1 is a vent type screw twin screw extruder having a barrel temperature of 330 ° C., a rotation speed of 300 rpm, a degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg), and a single vent (caliber: 15 mm, L / D: 45) is introduced from the hopper at a treatment rate of 432 g / h in terms of resin amount, and aniline is injected from the hopper after the hopper at a charging rate of 207 g / h, and the residence time in the shaft is 4.6 minutes. By extruding at a degree, transparent pellets P2 were obtained. The weight average molecular weight of the acrylic resin of the pellet P2 was 94,000. This acrylic resin has a repeating unit in which R ¹ is a methyl group, R ² is a hydrogen atom and R ³ is a phenyl group in formula (1), and R ⁴ is a hydrogen atom in formula (2). R ⁵ is a methyl group, R ⁶ is an acrylic resin having a repeating unit having a methyl group and a glass transition temperature of 180 ° C. The imidation ratio of the acrylic resin of the pellet P2 is 55.6%, the content of the repeating unit represented by the formula (2) is 27.4% by mass, and the stress optical coefficient (Cr) is 0.20 × 10 ^−9. Pa ⁻¹ , acid value was 1.32 mmol / g.

Next, the pellet P2 is a vent type screw twin screw extruder having a barrel temperature of 280 ° C., a rotation speed of 300 rpm, a reduced pressure of 13.3 to 400 hPa (10 to 300 mmHg), and a vent number of 1 (caliber: 15 mm, L / D: 45), introduced from the hopper at a processing rate of 900 g / h in terms of resin amount, and after the hopper, 16.0 parts by mass of dimethyl carbonate and 0.2 parts by mass of diazabicyclone with respect to the raw material resin. A mixed liquid of decene was injected with a liquid pump and extruded with an in-shaft residence time of about 1.9 minutes to obtain transparent pellets P3. The weight average molecular weight of the acrylic resin of the pellet P3 was 80,000. This acrylic resin has a repeating unit in which R ¹ is a methyl group, R ² is a hydrogen atom and R ³ is a phenyl group in formula (1), and R ⁴ is a hydrogen atom in formula (2). R ⁵ is a methyl group, R ⁶ is a methyl group, and the acrylic resin has a glass transition temperature of 159 ° C. The imidation ratio of the acrylic resin of the pellet P3 is 52.3%, the content of the repeating unit represented by the formula (2) is 48.8% by mass, and the stress optical coefficient (Cr) is −0.15 × 10 ^{−. 9} Pa ⁻¹ , and the acid value was 0.05 mmol / g.

  Next, the pellet P3 is put into a single screw extruder (caliber: 20 mm, L / D: 25), the T die temperature is adjusted to 285 ° C., and melt extrusion is performed from a coat hanger type T die (width 150 mm). It discharged on the cooling roll with a roll temperature of 155 degreeC, and produced 160 micrometer-thick unstretched film A1.

(2-2) Production Example 2 (Production of Easy Adhesive Composition B1)
Polyester-acrylic composite resin having epoxy group (Takamatsu Yushi Co., Ltd., Pesresin A-645GH, solid content 30% by mass) 25 parts by mass, polyester-acrylic composite resin having epoxy group and carboxyl group (Takamatsu Yushi Co., Ltd., Pesresin A -647GEX, solid content 20 mass%) 30 mass parts, polyvinyl alcohol (manufactured by Kuraray Co., Ltd., PVA205) 10 mass% aqueous solution 15 mass parts, emulsion containing amorphous silica fine particles (manufactured by Nippon Shokubai Co., Ltd., Seahoster KE-W10, average particle size) Mixing 1.0 parts by mass (primary particle size) 0.11 μm, particle size distribution index 1.1, solid content 15% by mass) and 80 parts by mass of pure water, an emulsion-like dispersion for easy adhesion Composition B1 was obtained.

(2-3) Production Example 3 (Production of Easy Adhesive Composition B2)
Epoxy group-containing acrylic resin (Takamatsu Yushi Co., Ltd., MYX1065, solid content 30% by mass) 20 parts by mass, polyvinyl alcohol (Kuraray Co., Ltd., PVA205) 10% by mass aqueous solution, emulsion containing amorphous silica fine particles (Japan) A catalyst company, Seahoster KE-W10, an average particle diameter (primary particle diameter) of 0.11 μm, a particle size distribution index of 1.1, a solid content of 15% by mass, 1.0 part by mass, and 40 parts by mass of pure water were mixed. Thus, an easy-adhesion composition B2 which is an emulsion-like dispersion was obtained.

(2-4) Production Example 4 (Production of Hard Coat Coating Composition H1)
15 parts by mass of tetrafunctional acrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., AD-TMP), 0.6 parts by mass of photopolymerization initiator (manufactured by Ciba Specialty Chemicals (currently BASF Japan), Irgacure (registered trademark) 184), and methyl ethyl ketone 14 .4 parts by mass was mixed to obtain a hard coat coating composition H1.

(3) Production of transparent conductive film (3-1) Example 1
After coating the easy-adhesion composition B1 prepared in Production Example 2 on one side of the unstretched film A1 produced in Production Example 1 so that the thickness of the coating film after drying is 400 nm, the film is 96 mm × Cut into 96 mm, using a sequential biaxial stretching machine (product number: X-6S, manufactured by Toyo Seiki Seisakusho Co., Ltd.) at a temperature of 179 ° C. at a stretching speed of 240 mm / min in the machine direction (MD direction) and the transverse direction (TD Biaxial stretching was sequentially performed so that the stretching ratio was 2 times in the order of (direction). After stretching, the obtained stretched film was quickly taken out from the stretching machine and cooled to obtain a film F1 having a base film thickness of 40 μm and a primer layer thickness of 100 nm. The stretched film F1 obtained had an in-plane retardation and a thickness direction retardation of 4.5 nm and −13.3 nm, respectively.

Next, the coating composition H1 produced in Production Example 4 was applied to the primer layer surface of the film F1 so that the thickness of the coating film after drying was 2 μm, and dried at 100 ° C. for 2 minutes. Subsequently, UV light having an integrated irradiation amount of 500 mJ / cm ² was irradiated to cure the coating composition H1 to obtain a film F2 having a hard coat layer on the surface.

  Next, an ITO layer was formed on the obtained film F2 using a sputtering apparatus (Osaka Vacuum Equipment Co., Ltd., opposed target type sputtering apparatus). For sputtering, an indium oxide-tin oxide target containing 10% by mass of tin oxide was used, and a vacuum degree of 0.5 Pa and an argon gas atmosphere added with 5% by volume of oxygen at a rate of 0.4 liter / sec for 20 minutes. Sputtering was performed to form an amorphous layer of ITO having a thickness of 30 nm. Subsequently, the film F2 on which the ITO amorphous layer is formed is taken out from the sputtering apparatus, heated in a heating oven at 150 ° C. for 90 minutes, and subjected to crystallization treatment, whereby the intended transparent conductive film I1 is obtained. Obtained. The surface resistance value of the obtained transparent conductive film I1 was 130Ω / □. Further, when the transparent conductive film I1 was visually confirmed, no rainbow-like interference was observed.

(3-2) Example 2
A substrate film having a thickness of 40 μm and a primer layer having a thickness of 100 nm was used in the same manner as in Example 1 except that the easy-adhesion composition B2 prepared in Production Example 3 was used instead of the easy-adhesion composition B1. Film F3 was obtained. The stretched film F3 obtained had an in-plane retardation and a thickness direction retardation of 4.2 nm and −12.7 nm, respectively.

  Next, in the same manner as in Example 1, the coating composition H1 was applied to the primer layer surface of the film F3 and cured to obtain a film F4 having a hard coat layer on the surface. On the obtained film F4, an ITO layer was formed and crystallized in the same manner as in Example 1 to obtain a transparent conductive film I2. The surface resistance value of the obtained transparent conductive film I2 was 128Ω / □. Further, when the transparent conductive film I2 was visually confirmed, no rainbow-like interference was observed.

(3-3) Comparative Example 1
The unstretched film (A1) produced in Production Example 1 was cut into 96 mm × 96 mm, and 240 mm / min at a temperature of 179 ° C. using a sequential biaxial stretching machine (manufactured by Toyo Seiki Seisakusho, product number: X-6S). Biaxial stretching was performed sequentially so that the stretching ratio was doubled in the order of the machine direction (MD direction) and the transverse direction (TD direction) at the stretching speed of. After stretching, the obtained stretched film was quickly taken out from the stretching machine and cooled to obtain a film F5 having a base film thickness of 40 μm. The stretched film F5 obtained had an in-plane retardation and a thickness direction retardation of 4.3 nm and -13.0 nm, respectively.

Next, the coating composition H1 produced in Production Example 4 was applied to one side of the film F5 so that the thickness of the coating film after drying was 2 μm, and dried at 100 ° C. for 2 minutes. Subsequently, UV light with an integrated irradiation amount of 500 mJ / cm ² was irradiated to cure the coating composition H1 to obtain a film F6 having a hard coat layer on the surface. On the obtained film F6, an ITO layer was formed and crystallized in the same manner as in Example 1 to obtain a transparent conductive film I3. The obtained transparent conductive film I3 had a surface resistance value of 126Ω / □. Moreover, when the transparent conductive film I3 was confirmed visually, interference like iridescent was confirmed.

  The transparent conductive film of the present invention can be suitably applied to a touch panel used in combination with a display element such as a liquid crystal display or a plasma display.

Claims (7)

A transparent conductive film in which a primer layer, a hard coat layer, and a transparent conductive layer are laminated in this order on at least one side of a base film,
The said base film contains acrylic resin which has a ring structure in a principal chain and whose glass transition temperature is 140 degreeC or more, The transparent conductive film characterized by the above-mentioned. The transparent conductive film according to claim 1, wherein the acrylic resin has a repeating unit represented by the following formula (1) and a repeating unit represented by the following formula (2).
[In Formula (1), R < ¹ > and R < ² > represent a hydrogen atom or a C1-C8 alkyl group each independently, and R < ³ > represents a ring structure. ]
[In the formula (2), R ⁴ and R ⁵ each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and R ⁶ represents an alkyl group having 1 to 18 carbon atoms or 3 to 3 carbon atoms. 12 represents a cycloalkyl group or an aryl group having 6 to 10 carbon atoms. ]   The acrylic resin has a repeating unit represented by the formula (1) in a content of 5% by mass to 85% by mass and a repeating unit represented by the formula (2) in a content of 15% by mass to 95% by mass. The transparent conductive film according to claim 2. The absolute value of the stress optical coefficient (Cr) of the acrylic resin is 0.3 × 10 ⁻⁹ Pa ⁻¹ or less. The transparent conductive film according to claim 1.   The transparent conductive film as described in any one of Claims 1-4 in which the said primer layer contains resin chosen from the group which consists of a polyester resin, an acrylic resin, a urethane resin, and these composite resins.   The transparent conductive film according to claim 5, wherein the primer layer further contains a water-soluble resin.   The transparent conductive film according to claim 5 or 6, wherein the primer layer further contains fine particles.