TWI807141B - Transparent conductive film laminate - Google Patents

Abstract

The object of the present invention is to provide a transparent conductive thin film laminate in which curling and outgassing are suppressed. The solution is to use a base film containing polycarbonate resin, the dimensional shrinkage rate is small in the first direction and the second direction perpendicular to the first direction, and the number of MIT is 500 times or more.

Description

Transparent conductive thin film laminate

The present invention relates to a transparent conductive thin film laminate.

Transparent conductive films used in touch panels, etc., are temporarily bonded to a carrier film to form a laminate during actual use, and the laminate is used for manufacturing, transportation, storage, etc. However, in the case of conventional transparent conductive thin film laminates, curling may occur in the heating step, resulting in insufficient production efficiency.

prior art literature patent documents Patent Document 1: Japanese Patent Laid-Open No. 2017-190406

The problem to be solved by the invention

The present invention was made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a transparent conductive thin film laminate in which curling and outgassing are suppressed. means for solving problems

The transparent conductive film laminate in the embodiment of the present invention includes: a conductive film including a resin film and a conductive film; and a carrier film having a base film made of polycarbonate resin and an adhesive layer arranged on one side of the base film, and is temporarily bonded to the conductive film in a peelable state through the adhesive layer; the carrier film is laminated on the opposite side of the conductive film; the glass transition temperature (Tg) of the base film is 150° C. 0.2% or less in the first direction and the second direction perpendicular to the first direction, respectively, and the number of MITs is 500 or more. In one embodiment, the above-mentioned polycarbonate resin is substantially formed by a structural unit represented by the following general formula (I) and a structural unit represented by the following general formula (II), and satisfies the following conditions (a) to (d), the structural unit represented by the following general formula (I) is derived from an aliphatic diol compound having an aliphatic hydrocarbon group bonded to a terminal hydroxyl group, [chemical formula 1] (通式(I)中，Q表示可包含不同種原子之碳數3以上烴基，R ₁ ~R ₄分別獨立表示選自於由氫原子、碳數1~30脂肪族烴基及碳數6~20芳香族烴基所構成群組中之基團，n及m分別獨立表示0~10的整數；惟，Q不含與末端羥基鍵結的脂肪族烴基時，n及m分別獨立表示1~10的整數；且，R ₁及R ₂中之至少一者、與R ₃及R ₄中之至少一者分別選自由氫原子及脂肪族烴基所構成之群組)； [化學式2] (In the general formula (II), R and R _{independently} represent a halogen atom, an alkyl group with ₁ to 20 carbons, an alkoxy group with 1 to 20 carbons, a cycloalkyl group with 6 to 20 carbons, an aryl group with 6 to 20 carbons, a cycloalkoxy group with 6 to 20 carbons, or an aryloxy group with 6 to 20 carbons, p and q represent integers from 0 to 4, and X represents a single bond or a group selected from the divalent organic groups shown in the following general formula (II')); [Chemical formula 3] (In the general formula (II'), R ₃ and R ₄ independently represent a hydrogen atom, an alkyl group with 1 to 10 carbons, or an aryl group with 6 to 10 carbons, and R ₃ and R ₄ can also be bonded to form an aliphatic ring); (a) has the structure shown in the following general formula (III): [Chemical formula 4] (In the general formula (III), k represents an integer greater than 4, i represents an integer greater than 1, l represents an integer greater than 1, and k' represents an integer of 0 or 1; R represents a straight-chain or branched hydrocarbon group, a phenyl group that may contain fluorine, or a hydrogen atom; however, in the total amount of the resin, more than 70% by weight is i=1); (Mw) is 30,000 to 100,000; (d) With respect to the total amount of structural units constituting the polycarbonate resin, the structural units represented by the following general formulas (1) and (2) contain 2000 ppm or less in terms of bisphenolic acid conversion values, general formula (1): [chemical formula 5] General formula (2): [Chemical formula 6] (X in the above-mentioned general formulas (1) and (2) is the same as X in the general formula (II)). In one embodiment, the above-mentioned carrier film has a thickness of 15 μm˜100 μm. Invention effect

According to an embodiment of the present invention, in a transparent conductive film laminate having a transparent conductive film and a carrier film, by using a base film containing a predetermined polycarbonate resin, having a small dimensional shrinkage in the first direction and a second direction perpendicular to the first direction, and having an MIT number of 500 or more, a transparent conductive film laminate in which curl and outgassing are suppressed can be obtained.

Hereinafter, preferred embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

A. Overall configuration of transparent conductive film laminate Fig. 1 is a schematic cross-sectional view of a transparent conductive thin film laminate according to an embodiment of the present invention. A transparent conductive film laminate 100 of the illustrated example has a transparent conductive film 10 and a carrier film 20 . The transparent conductive film 10 represents a resin film 14 and a conductive layer 11 thereon. The carrier film 20 represents a base film 22 and an adhesive layer 21 , and is temporarily bonded to the transparent conductive film 10 in a peelable state through the adhesive layer 21 . The carrier film can optionally also have an anti-adhesion hardcoat (ABHC) layer 23 .

In the embodiment of the present invention, the glass transition temperature (Tg) of the base film 22 is above 150°C, preferably above 155°C. In addition, the dimensional shrinkage of the base film 22 at 145° C. is 0.2% or less in each of the first direction and the second direction perpendicular to the first direction. The first direction corresponds to, for example, the MD direction in a manufacturing method described later, and the second direction corresponds to, for example, the TD direction. In addition, the number of MITs of the base film 22 is 500 or more. As long as the glass transition temperature (Tg), dimensional shrinkage at 145°, and MIT number of the base film 22 are within the above ranges, a transparent conductive film laminate in which curling and outgassing are suppressed can be obtained. In addition, the number of times of folding resistance of the base film 22 is preferably 100 or more.

The thickness of the carrier film 20 is preferably 15 μm-100 μm, more preferably 15 μm-80 μm, and more preferably 15 μm-60 μm. As long as the thickness of the carrier film is within the above range, the generation of curl and outgassing is suppressed, and a transparent conductive film laminate having excellent folding resistance can be obtained. In addition, the thickness of the carrier film refers to the total thickness when the base film, the adhesive layer and, if necessary, the anti-adhesion hard coat (ABHC) are laminated.

B. Transparent conductive film The transparent conductive film 10 according to the embodiment of the present invention includes a resin film 14 and a conductive layer 11 . The conductive layer is typically formed on the viewing side surface of the resin film. The transparent conductive film may also have a refractive index matching (IM) layer 12 , a hard coat (HC) layer 13 and/or an anti-adhesion hard coat (ABHC) layer 15 as needed.

(resin film) The resin film may be composed of any appropriate resin. Examples of the resin constituting the resin film include cycloolefin resin (COP) and polycarbonate resin. The details of the cycloolefin-based resin (COP) are described in, for example, JP-A-2016-107503. The description of this publication is incorporated by reference in this specification.

The thickness of the resin film is preferably 10 μm-80 μm, more preferably 10 μm-60 μm, and more preferably 10 μm-40 μm.

(conductive layer) The conductive layer represents a transparent conductive layer. The total light transmittance of the conductive layer is preferably above 80%, more preferably above 85%, and more preferably above 90%.

The density of the conductive layer is preferably 1.0g/cm ³ ~10.5g/cm ³ , more preferably 1.3g/cm ³ ~8.0g/cm ³ .

The surface resistance of the conductive layer is preferably 0.1Ω/□~1000Ω/□, more preferably 0.5Ω/□~500Ω/□, and more preferably 1Ω/□~250Ω/□.

A representative example of the conductive layer includes a conductive layer made of a metal oxide. Examples of metal oxides include indium oxide, tin oxide, zinc oxide, indium-tin composite oxide, tin-antimony composite oxide, zinc-aluminum composite oxide, and indium-zinc composite oxide. Among them, indium-tin composite oxide (ITO) is preferable.

The thickness of the conductive layer is preferably 0.01 μm to 0.06 μm, more preferably 0.01 μm to 0.045 μm. If it is the said range, the electroconductive layer excellent in electroconductivity and translucency can be obtained.

The conductive layer can typically be formed by sputtering on the surface of the resin film.

(Index matching (IM) layer) The IM layer may be formed on one side of the conductive layer. As for the IM layer, a well-known configuration in the industry can be employed, so detailed description is omitted.

(Hard Coat (HC) Layer) The HC layer may be formed between the above-mentioned IM layer and the resin film. As for the HC layer, a well-known configuration in the industry can be employed, and thus detailed description thereof will be omitted.

(Anti-Adhesion Hardcoat (ABHC) layer) The ABHC layer may be formed on the surface of the resin film opposite to the HC layer. The details of the ABHC layer are described in, for example, JP-A-2016-107503. The description of this publication is incorporated by reference in this specification.

C. Carrier film The carrier film 20 includes an adhesive layer 21 and a base film 22 . The carrier film 20 can optionally have an anti-adhesion hardcoat (ABHC) layer 23 .

(base film) The substrate for a transparent conductive film according to an embodiment of the present invention is composed of a film made of polycarbonate resin. The polycarbonate resin used in the present invention is substantially composed of the structural unit represented by the above general formula (I) and the structural unit represented by the general formula (II).

(1) Structural unit shown in general formula (I) The structural unit represented by the general formula (I) is derived from an aliphatic diol compound. Here, the aliphatic diol compound in the present invention is a compound having an aliphatic hydrocarbon group bonded to a terminal hydroxyl group. The terminal hydroxyl group refers to a hydroxyl group that contributes to the formation of a carbonate bond with the aromatic polycarbonate prepolymer by transesterification.

Examples of the aliphatic hydrocarbon group include alkylene groups and cycloalkylene groups, some of which may be substituted with aromatic groups, heterocyclic groups, and the like. [chemical formula 7]

In the above general formula (I), Q represents a hydrocarbon group having 3 or more carbon atoms which may contain different types of atoms. The lower limit of the carbon number of the hydrocarbon group is preferably 3, more preferably 6, and more preferably 10, and the upper limit is preferably 40, more preferably 30, and more preferably 25.

Examples of the different kinds of atoms include oxygen atoms (O), sulfur atoms (S), nitrogen atoms (N), fluorine atoms (F) and silicon atoms (Si). Among these, oxygen atom (O) and sulfur atom (S) are particularly desirable. The hydrocarbon group may be linear, branched or cyclic. In addition, Q may contain ring structures such as aromatic rings and heterocyclic rings.

In the above general formula (I), R ₁ , R ₂ , R ₃ and R ₄ each independently represent a group selected from the group consisting of a hydrogen atom, preferably an aliphatic hydrocarbon group having 1 to 30 carbons, more preferably an aliphatic hydrocarbon group having 1 to 10 carbons, and an aromatic hydrocarbon group preferably having 6 to 20 carbons, more preferably an aromatic hydrocarbon group having 6 to 10 carbons.

Specific examples of the aliphatic hydrocarbon group include linear or branched alkyl groups and cycloalkyl groups. Examples of the alkyl group include methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, n-hexyl, and isohexyl. A cyclohexyl group is mentioned as a cycloalkyl group. A phenyl group, a naphthyl group, etc. are mentioned as an aromatic hydrocarbon group.

However, at least one of R ₁ and R ₂ , and at least one of R ₃ and R ₄ are respectively selected from the group consisting of a hydrogen atom and an aliphatic hydrocarbon group. In particular, R ₁ to R ₄ preferably independently represent a group selected from the group consisting of a hydrogen atom and an aliphatic hydrocarbon group preferably having 1 to 30 carbon atoms, more preferably an aliphatic hydrocarbon group having 1 to 10 carbon atoms. Straight-chain or branched-chain alkyl groups are mentioned as particularly preferable aliphatic hydrocarbon groups. Examples of the alkyl group include methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, tertiary butyl, and isopentyl.

In addition, it is most desirable that R ₁ to R ₄ are all hydrogen atoms. That is, the aliphatic diol compound from which the above general formula (I) can be derived is preferably a primary diol compound, more preferably a primary diol compound other than straight-chain aliphatic diol.

n and m each independently represent an integer of preferably 0-10, more preferably 0-4. However, when Q does not contain an aliphatic hydrocarbon group bonded to a terminal hydroxyl group, n and m each independently represent an integer of preferably 1-10, more preferably 1-4.

The aliphatic diol compound from which the above structural unit (I) can be derived is a compound having a dihydric hydroxyl group represented by the following general formula (A). In the general formula (A), Q, R ₁ to R ₄ , n and m are the same as those in the above-mentioned general formula (I).

[chemical formula 8]

Specific examples of the terminal structures "HO-(CR ₁ R ₂ )n-" and "-(CR ₃ R ₄ )m-OH" include the following structures.

[chemical formula 9]

[chemical formula 10] Ra, Rb=hydrogen, straight chain or branched chain alkyl, phenyl, naphthyl, m=1 or more integer Ra, Rb=hydrogen, straight chain or branched chain alkyl, phenyl, naphthyl, m=1 or more integer

(2) Structural unit shown in general formula (II) The aromatic polycarbonate forming unit of the polycarbonate resin of the present invention is a structural unit represented by general formula (II).

[chemical formula 11]

In the general formula (II), R and _R independently represent a halogen atom, an alkyl group with ₁ to 20 carbons, an alkoxy group with 1 to 20 carbons, a cycloalkyl group with 6 to 20 carbons, an aryl group with 6 to 20 carbons, a cycloalkoxy group with 6 to 20 carbons, or an aryloxy group with 6 to 20 carbons. p and q represent an integer of 0 to 4. X represents a single bond or a group selected from divalent organic groups represented by the following general formula (II').

[chemical formula 12]

In the general formula (II'), R ₃ and R ₄ independently represent a hydrogen atom, an alkyl group with 1-10 carbons, or an aryl group with 6-10 carbons, and R ₃ and R ₄ can also be bonded to form an aliphatic ring.

Examples of the aromatic dihydroxy compound from which the structural unit represented by the general formula (II) can be derived include compounds represented by the following general formula (II").

[chemical formula 13]

In the above general formula (II"), R ₁ to R ₂ , p, q and X are respectively the same as those in the above general formula (II).

Specific examples of the aromatic dihydroxy compound include bis(4-hydroxyphenyl)methane, 1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxyphenyl)octane, bis(4-hydroxyphenyl)phenylmethane, 1,1-bis(4-hydroxyphenyl)-1-phenylethane, bis(4-hydroxyphenyl)diphenylmethane, 2, 2-bis(4-hydroxy-3-methylphenyl)propane, 1,1-bis(4-hydroxy-3-tertiary butylphenyl)propane, 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3-phenylphenyl)propane, 2,2-bis(3-cyclohexyl-4-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3-bromophenyl)propane, 2,2-bis(3,5 -Dibromo-4-hydroxyphenyl)propane, 1,1-bis(4-hydroxyphenyl)cyclopentane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 2,2-bis(4-hydroxy-3-methoxyphenyl)propane, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxy-3,3'-dimethylphenyl ether, 4,4'-dihydroxyphenylene sulfide, 4,4'-dihydroxy-3,3'-dimethyldiphenylsulfide, 4, 4'-dihydroxydiphenylene, 4,4'-dihydroxy-3,3'-dimethyldiphenylene, 4,4'-dihydroxydiphenylene, 4,4'-dihydroxydiphenylene, 4,4'-dihydroxy-3,3'-dimethyldiphenylene, etc.

Among these, 2,2-bis(4-hydroxyphenyl)propane is mentioned as a more preferable example from the viewpoint of stability as a monomer and the ease of obtaining a substance containing a small amount of impurities therein.

As the aromatic polycarbonate forming unit in the present invention, for the purpose of controlling glass transition temperature, improving fluidity, improving refractive index, reducing birefringence, etc. to control optical properties, etc., structural units derived from various monomers (aromatic dihydroxy compounds) can be combined as needed.

(3) Element (a) The polycarbonate resin of the present invention is characterized by having a structure represented by the following general formula (III). Here, in the general formula (III), (I) represents the structural unit represented by the general formula (I), and (II) represents the structural unit represented by the general formula (II).

[chemical formula 14]

In the above general formula (III), R represents a linear or branched hydrocarbon group, a phenyl group which may contain fluorine, or a hydrogen atom. Specifically, methyl, propyl, isopropyl, ethyl, butyl, isobutyl, pentyl, isopentyl, hexyl, tetrafluoropropyl, tertiary butyl-phenyl, pentafluorophenyl, etc. are mentioned.

In the above general formula (III), k represents the average chain length of a chain (aromatic polycarbonate chain) composed of aromatic polycarbonate-forming units. The aromatic polycarbonate forming unit is a structural unit constituting the main body of the polycarbonate resin of the present invention, and the aromatic polycarbonate chain formed therefrom can form the main polymer structure of the polycarbonate resin. k is preferably 4 or more, more preferably 4-100, and more preferably 5-70. If the chain length does not have a certain length or more, the structural portion represented by "-(I)i-" will increase relatively, and as a result, the random copolymerization of the polycarbonate resin of the present invention will increase, and the heat resistance, which is the original characteristic of the polycarbonate resin, will tend to be lost.

The structural unit "-(II)k-" (aromatic polycarbonate chain) is a structural unit derived from an aromatic polycarbonate prepolymer, and its weight average molecular weight (Mw) is preferably 5,000-60,000, more preferably 10,000-50,000, more preferably 10,000-40,000, particularly preferably 15,000-35,000.

When the molecular weight of the aromatic polycarbonate chain is too low, the polycarbonate resin of the present invention may be greatly influenced by the physical properties of the copolymerization component. Although the physical properties can be improved by this, the effect of maintaining the useful physical properties of the aromatic polycarbonate may not be sufficient.

When the molecular weight of the aromatic polycarbonate chain is too high, the polycarbonate resin of the present invention may not be a polycarbonate resin having high fluidity while maintaining the useful physical properties of the aromatic polycarbonate.

i represents the average chain length of the site "-(I)i-" composed of structural units derived from aliphatic diol compounds. i is preferably 1 or more, more preferably 1-5, more preferably 1-3, particularly preferably 1-2, most preferably 1, and the closer the average chain length is to 1, the better. If the average chain length of the aliphatic diol moiety "-(I)i-" is too long, heat resistance and mechanical strength will decrease, and the effects of the present invention will not be obtained.

l represents the average chain length of the structural unit "-[-(II)k-(I)i-]l-" composed of an aromatic polycarbonate chain and an aliphatic diol moiety. l is 1 or more, preferably 1-30, more preferably 1-20, particularly preferably 1-10. k' is preferably an integer of 0 or 1. That is, the aliphatic diol moiety "-(I)i-" may have an aromatic polycarbonate chain on both sides, or may have an aromatic polycarbonate chain on only one side, but most often have an aromatic polycarbonate chain on both sides.

In the aforementioned polycarbonate resin, the ratio (molar ratio) of the aromatic polycarbonate chain "-(II)k-" to the aliphatic diol part "-(I)i-" is not particularly limited, and is preferably "-(II)k-"/"-(I)i-"=0.1~3, more preferably 0.6~2.5, especially 2, based on the average value of the polycarbonate resin as a whole. In addition, k/l is not particularly limited, preferably 2-200, more preferably 4-100.

However, in the case of the aforementioned polycarbonate resin of the present invention, among the total amount of polymer molecules constituting it, preferably 70% by weight or more, more preferably 80% by weight or more, and more preferably 90% by weight or more, particularly preferably 95% by weight or more, of the polymer molecules is i=1. That is, a resin is generally an aggregate of polymer compounds (polymer molecules) having various structures and molecular weights, but the polycarbonate resin of the present invention is characterized in that it is an aggregate of polymer compounds having a structure in which 70% by weight or more of a long-chain aromatic polycarbonate chain (-(II)k-) is bonded to one structural unit (-(I)-) derived from an aliphatic diol compound. When the polymer compound with i=1 is less than 70% by weight, the ratio of the copolymerization component is high, and therefore the physical properties of the copolymerization component are easily affected, and the original physical properties of the aromatic polycarbonate cannot be maintained. The ratio of the polymer compound with i=1 in the polycarbonate resin of the present invention can be analyzed by 1H-NMR analysis of the polycarbonate resin.

(4) Element (b) In the polycarbonate resin of the present invention, the ratio of the structural unit represented by the aforementioned general formula (I) to the structural unit represented by the general formula (II) is preferably 1-30:99-70 (molar ratio)%, more preferably 1-25:99-75 (molar ratio), and more preferably 1-20:99-80 (molar ratio).

If the ratio of the structural unit represented by the general formula (I) is too small, the high molecular weight and high fluidity conditions characteristic of the polycarbonate resin will not be satisfied; if too much, the original excellent physical properties of the aromatic polycarbonate resin such as mechanical strength and heat resistance will be damaged.

The polycarbonate resin of the present invention may also contain structures derived from other copolymerization components within the scope of not departing from the gist of the present invention. Ideally, the polycarbonate resin of the present invention contains a structural unit represented by general formula (I) that is preferably 1 to 30 mol%, more preferably 1 to 25 mol%, and more preferably 1 to 20 mol% relative to the total amount of structural units.

(5) Element (c) The weight average molecular weight (Mw) of the polycarbonate resin of the present invention is preferably 30,000-100,000, more preferably 30,000-80,000, and more preferably 35,000-75,000, which is high molecular weight and has high fluidity.

If the weight average molecular weight of the polycarbonate resin is too low, when it is used for blow molding, extrusion molding, etc., the melt tension will become low, and it will tend to sag, making it impossible to obtain a satisfactory molded product. On the other hand, when used for injection molding or the like, satisfactory molded products cannot be obtained due to stringing or the like. In addition, physical properties such as mechanical properties and heat resistance of the obtained molded article will be lowered. Furthermore, the oligomer region increases, and physical properties such as resistance to organic solvents also decrease.

When the weight-average molecular weight of the polycarbonate resin is too high, injection molding of precision components and thin objects becomes difficult, and the molding cycle time becomes long, which adversely affects production costs. Therefore, measures such as increasing the molding temperature are required, but at high temperatures, there is a possibility that gelation, different structures, and N value increase may occur.

(6) Requirement (d) In the polycarbonate resin of the present invention, the structural units include at least one of the structural units represented by the following general formulas (1) and (2) (hereinafter referred to as "structural unit (1)" and "structural unit (2)") as different structures. X in the following general formulas (1) and (2) is the same as X in the above general formula (II).

Structural unit (1): [Chemical formula 15]

Structural unit (2): [Chemical formula 16]

In addition, the two structural formulas (i) and (ii) in the above structural formula (2) are isomers and cannot be distinguished analytically, so they are treated as the same structure in the present invention. Therefore, when referring to structural formula (2) in the present invention, it refers to any one or both of the above structural formulas (i) and (ii). In addition, the content of the structural unit (2) in this invention means the total amount of said 2 structural formulas (i) and (ii).

In the present invention, relative to the total amount of structural units constituting the aromatic polycarbonate resin, the content ratio of at least one structural unit among the above-mentioned structural units (1) and (2) is preferably 2000 ppm or less, more preferably 1500 ppm or less, preferably 1000 ppm or less, particularly preferably 500 ppm or less, most preferably 300 ppm or less in terms of bisphenol acid conversion value. If the contents of the structural units (1) and (2) are both greater than 2000 ppm, the degree of branching will increase and the thermal stability will tend to decrease. Moreover, since these structural units are naturally occurring branched chains, they have the following disadvantages: it is difficult to simply control the degree of branching by the amount of branching agent added, or the fluidity is reduced and the formability is deteriorated.

As mentioned above, in the present invention, the content ratio of at least one of the above structural units (1) and (2) needs to be 2000ppm or less in terms of bisphenolic acid conversion value, which means that any one of the structural units (1) and (2) is 2000ppm or less. Structural unit (1) below 00 ppm. In particular, the structural unit (1) has a large influence on the retention stability and color tone, and when the ratio of the structural unit (1) is small, thermal stability and color tone are remarkably improved.

Ideally, the structural units (1) and (2) should be 2000ppm or less, more preferably 1000ppm or less, preferably 1000ppm or less, particularly preferably 500ppm or less, most preferably 300ppm or less, in terms of bisphenolic acid conversion.

In addition, ideally, the ratio of the structural units represented by the above-mentioned structural units (1) and (2) is preferably less than 5000ppm in terms of bisphenolic acid conversion value, more preferably less than 3000ppm, more preferably less than 2000ppm, especially preferably less than 1000ppm, most preferably less than 600ppm.

Details of the structural units represented by the general formulas (I) and (II) used in the present invention are described in, for example, JP-A-2014-101417. The description of this publication is incorporated by reference in this specification.

As the polycarbonate resin, commercially available items can be used. As a commercial item, the product name "Iupizeta (registered trademark)" by Mitsubishi Gas Chemical Co., Ltd. is mentioned, for example.

The thickness of the base film is preferably 10 μm-80 μm, more preferably 10 μm-60 μm, and more preferably 10 μm-40 μm.

The elastic modulus of the base film should be 50MPa~350MPa at a stretching speed of 100mm/min. As long as the modulus of elasticity is within the above range, a base film excellent in conveyability and handleability can be obtained. According to the embodiment of the present invention, excellent elastic modulus (strength) and excellent flexibility or bending resistance (softness) as described above can be achieved at the same time. In addition, elastic modulus is measured based on JISK7127:1999.

The tensile elongation of the base film should be 70%~200%. As long as the tensile elongation is within the above-mentioned range, there is an advantage that it is difficult to break during transportation. In addition, tensile elongation is measured based on JISK6781.

(Manufacturing method of base film) The method for producing a base film according to an embodiment of the present invention includes: forming a film-forming material (resin composition) containing the polycarbonate resin described in item A above into a film; and stretching the formed film.

The film-forming material may contain other resins as described above in addition to the above-mentioned polycarbonate resin, may contain additives, and may contain a solvent. As the additive, any appropriate additive can be employed according to the purpose. Specific examples of additives include reactive diluents, plasticizers, surfactants, fillers, antioxidants, antiaging agents, ultraviolet absorbers, leveling agents, thixotropic agents, antistatic agents, conductive materials, and flame retardants. The number, type, combination, addition amount, etc. of the additives can be appropriately set according to the purpose.

As a method of forming a thin film from a thin film forming material, any appropriate forming method can be adopted. Specific examples include compression molding, transfer molding, injection molding, extrusion molding, blow molding, powder molding, FRP molding, casting coating (such as casting), calendering, and hot pressing. It is preferably extrusion molding or casting coating. This is because the smoothness of the obtained film can be improved and good optical uniformity can be obtained. The molding conditions can be appropriately set according to the composition and type of the resin used, desired properties of the base film, and the like.

The film stretching method is typically biaxial stretching, and more specifically, sequential biaxial stretching or simultaneous biaxial stretching. This is because a base film having a small in-plane retardation can be obtained. Sequential biaxial stretching or simultaneous biaxial stretching is typically performed using a tenter stretching machine. Therefore, the stretching direction of the film typically refers to the longitudinal direction and the width direction of the film.

The stretching temperature varies depending on the desired in-plane retardation and thickness of the base film, the type of resin to be used, the thickness of the film to be used, the stretching ratio, and the like. Specifically, the stretching temperature relative to the glass transition temperature (Tg) of the film is preferably Tg+5°C~Tg+50°C, more preferably Tg+10°C~Tg+40°C. By performing stretching at such a temperature, a base film having appropriate characteristics can be obtained in the embodiment of the present invention.

The stretching ratio varies depending on the desired in-plane retardation and thickness of the base film, the type of resin to be used, the thickness of the film to be used, the stretching temperature, and the like. When using biaxial stretching (for example, sequential biaxial stretching or simultaneous biaxial stretching), the difference between the stretching ratio in the first direction (such as the length direction) and the stretching ratio in the second direction (such as the width direction) should be as small as possible, and more preferably substantially equal. With such a configuration, a resin film having a small in-plane retardation can be obtained. When using biaxial stretching (for example, sequential biaxial stretching or simultaneous biaxial stretching), the stretching ratio can be, for example, 1.1 times to 3.0 times in the first direction (such as the longitudinal direction) and the second direction (such as the width direction), respectively.

In the embodiment of the present invention, the stretching speed is preferably below 10%/sec, more preferably below 7%/sec, more preferably below 5%/sec, especially preferably below 2.5%/sec. A base film having a small in-plane phase difference can be obtained by stretching a film containing the above-mentioned specific polycarbonate resin at the above-mentioned low stretching speed. The lower limit of the stretching speed may be, for example, 1.2%/sec. If the stretching speed is too low, the productivity may become impractical. In addition, when using biaxial stretching (for example, sequential biaxial stretching or simultaneous biaxial stretching), the difference between the stretching speed in the first direction (such as the length direction) and the stretching speed in the second direction (such as the width direction) should be as small as possible, and more preferably substantially equal. With such a configuration, the in-plane retardation Re(550) of the base film can be reduced.

(adhesive layer) As the pressure-sensitive adhesive layer, as long as it has transparency, it can be used without particular limitation. Specifically, for example, acrylic polymers, silicone polymers, polyesters, polyurethanes, polyamides, polyvinyl ethers, vinyl acetate/vinyl chloride copolymers, modified polyolefins, epoxy-based, fluorine-based, natural rubber, synthetic rubber and other rubber-based polymers can be appropriately selected and used. In particular, an acrylic adhesive is preferably used from the viewpoint of excellent optical transparency, moderate wettability, cohesiveness, adhesiveness, and other adhesive properties, as well as excellent weather resistance and heat resistance.

As the adhesive constituting the adhesive layer, a tackifier, a plasticizer, a filler, an antioxidant, an ultraviolet absorber, a silane coupling agent, and the like can be appropriately used as needed. The thickness of the adhesive layer is preferably 5 μm-100 μm, more preferably 10 μm-50 μm, and more preferably 15 μm-35 μm.

(Anti-Adhesion Hardcoat (ABHC) layer) Since it has the same structure as that of the ABHC layer in the transparent conductive film, detailed description thereof will be omitted. Example

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited by these examples. The measuring method of each characteristic in an Example is as follows. In addition, unless otherwise specified, "parts" and "%" in the examples are based on weight.

(1) MIT test The MIT test was performed in accordance with JIS P 8115. Specifically, the base films obtained in Examples and Comparative Examples were cut into lengths of 15 cm and widths of 1.5 cm, and used as measurement samples. Install the test sample (load 1.0kgf, fixture R: 0.38mm) on the MIT bending fatigue tester BE-202 (manufactured by TESTER SANGYO CO,.LTD.), repeat the bending at a test speed of 90cpm and a bending angle of 90° with 500 times as the upper limit, and take the number of times of bending when the test sample breaks as the test value. (2) Folding test The 180° bending test was repeated 100 times on the base films obtained in Examples and Comparative Examples, and the number of times of bending when the sample was broken was measured as the test value. (3) Size shrinkage The thermal shrinkage rates in the longitudinal direction (MD direction) and width direction (TD direction) of the base films obtained in Examples and Comparative Examples were measured as follows. Specifically, the base film was cut into widths of 100 mm and lengths of 100 mm (test pieces), four corners were given cross scratches, and the length (mm) before heating in the MD direction and TD direction of four points in the center of the cross scratches was measured using a CNC three-dimensional measuring machine (LEGEX774 manufactured by Mitutoyo Corporation). Then, it was thrown into an oven and heat-processed (145 degreeC, 60 minutes). After cooling at room temperature for 1 hour, measure the heated lengths (mm) in the MD direction and TD direction at 4 points of the four corners again using the CNC three-dimensional measuring machine, and substitute the measured values into the following formula to obtain the respective heat shrinkage rates in the MD direction and the TD direction. Thermal shrinkage rate (%)=[[length before heating (mm)-length after heating (mm)]/length before heating (mm)]×100 (4) Outgassing The base film obtained in the examples and comparative examples was cut into width 100mm, length 100mm (test piece), and an adhesive was applied on the side to be bonded with the transparent conductive film and the other side, and the adhesive side was attached to one side of the alkali glass to obtain a test piece. The obtained test piece was put into an autoclave under the conditions of 50° C. and 0.5 atmospheric pressure, and after 15 minutes, the sample was taken out, and those with no bubbles were marked as 0, and those with bubbles were marked as ×. (5) curly The transparent conductive layer film laminates obtained in Examples and Comparative Examples were cut into a size of 20 cm×20 cm. After heating at 145° C. for 60 minutes with the ITO side facing up, it was left to cool at room temperature (23° C.) for 1 hour. Then, the sample was placed on a horizontal surface with the ITO layer facing up, and the height (curl value A) of the central part from the horizontal surface was measured. The heights from the horizontal plane of the four corners were measured respectively, and the average value (curl value B) was calculated. The value (A-B) which subtracted the curl value B from the curl value A was calculated as the curl amount. When the curl value was in the range of 0 mm to 50 mm, it was marked as 0, and in other cases, it was marked as x.

>Example 1> 1-1. Production of transparent conductive film An anti-adhesion hard coat (ABHC) layer was formed on one surface of a polycycloolefin film made by Zeon Corporation in Japan under the product name "ZEONOR (registered trademark)" (thickness: 50 μm, Tg: 165° C.), and a hard coat (HC) layer was formed on the surface opposite to the ABHC layer. An index matching (IM) layer is formed on the surface of the HC layer on the side opposite to the resin film. ITO was sputtered on the surface of the IM layer opposite to the HC layer to form a conductive layer to obtain a transparent conductive film (thickness: 25 μm).

1-2. Production of polycarbonate resin film The product name "Iupizeta (registered trademark)" (Tg: 174°C) manufactured by Mitsubishi Gas Chemical Co., Ltd. as a polycarbonate resin was vacuum-dried at 120°C for 5 hours. Take the thin film film forming device of the machine, and produce a polycarbonate resin with a thickness of 100 μm.

1-3. Preparation of base film The polycarbonate resin film obtained above was simultaneously biaxially stretched twice in the longitudinal direction and the width direction, respectively, to obtain a base film. The obtained base film has an MIT number of more than 500 times, a folding endurance number of more than 100 times, and a dimensional change ratio (MD/TD) of 0.06/0.08.

1-4. Preparation of carrier film By general solution polymerization, an acrylic polymer having a weight average molecular weight of 600,000 was obtained with butyl acrylate/acrylic acid=100/6 (weight ratio). 6 parts by weight of an epoxy-based crosslinking agent (trade name "TETRAD C (registered trademark)" manufactured by Mitsubishi Gas Chemical Co., Ltd.) was added to 100 parts by weight of the acrylic polymer to prepare an acrylic adhesive. The acrylic adhesive obtained as described above was coated on the release-treated surface of the release-treated PET film, and heated at 120° C. for 60 seconds to form an adhesive layer with a thickness of 20 μm. Next, one side of the base film obtained above was bonded to a PET film via an adhesive layer. Then, the release-treated PET film was peeled off, and an anti-adhesion hard coat (ABHC) layer was formed on the surface opposite to the adhesive layer to produce a carrier film (thickness: 40 μm).

1-5. Production of transparent conductive thin film laminate The carrier film is temporarily bonded to the surface of the transparent conductive film on the side where the conductive film is not formed through the adhesive layer in a peelable state to form a transparent conductive film laminate. The obtained transparent conductive film laminate was subjected to the evaluations of (4) and (5) above. The results are shown in Table 1.

>Example 2> Except having set the thickness of a transparent conductive film to 15 micrometers, it carried out similarly to Example 1, and obtained the transparent conductive film. A carrier film was obtained in the same manner as in Example 1 except that the thickness was set to 25 μm. The MIT cycle of the base film used in the production of the carrier film is 500 or more, the folding cycle is 100 or more, and the dimensional change ratio (MD/TD) is 0.04/0.07. Using the above transparent conductive film and carrier film, a transparent conductive film laminate was obtained in the same manner as in Example 1. The obtained transparent conductive film laminate was subjected to the evaluations of (4) and (5) above. The results are shown in Table 1.

>Example 3> Except having set the thickness of a transparent conductive film to 40 micrometers, it carried out similarly to Example 1, and obtained the transparent conductive film. A carrier film was obtained in the same manner as in Example 1 except that the thickness of the carrier film was set to 100 μm. The base film used in the production of the carrier film has an MIT count of 500 or more, a folding endurance of 100 or more, and a dimensional change ratio (MD/TD) of 0.11/0.11. Using the above transparent conductive film and carrier film, a transparent conductive film laminate was obtained in the same manner as in Example 1. The obtained transparent conductive film laminate was subjected to the evaluations of (4) and (5) above. The results are shown in Table 1.

>Example 4> A transparent conductive film was obtained in the same manner as in Example 1 except that the product name "Iupizeta (registered trademark)" manufactured by Mitsubishi Gas Chemical Co., Ltd. was used as a polycarbonate resin. And in the same manner as in Example 1, a carrier film was obtained. The MIT cycle of the base film used in the production of the carrier film is 500 or more, the folding cycle is 100 or more, and the dimensional change ratio (MD/TD) is 0.04/0.07. Using the above transparent conductive film and carrier film, a transparent conductive film laminate was obtained in the same manner as in Example 1. The obtained transparent conductive film laminate was subjected to the evaluations of (4) and (5) above. The results are shown in Table 1.

>Comparative example 1> In the same manner as in Example 1, a transparent conductive film was obtained. Furthermore, except having used the polycarbonate (PC) resin film (Tg: 147 degreeC) as a carrier film, it carried out similarly to Example 1, and obtained the carrier film. The base film used in the production of the carrier film has an MIT count of 500 or more, a folding endurance of 100 or more, and a dimensional change ratio (MD/TD) of 0.13/0.1. Using the above transparent conductive film and carrier film, a transparent conductive film laminate was obtained in the same manner as in Example 1. The obtained transparent conductive film laminate was subjected to the evaluations of (4) and (5) above. The results are shown in Table 1.

>Comparative example 2> Except having made thickness into 40 micrometers, it carried out similarly to Example 1, and obtained the transparent conductive film. A carrier film was obtained in the same manner as in Example 1 except that the thickness was set to 110 μm. The base film used in the production of the carrier film has an MIT count of 500 or more, a folding endurance of 100 or more, and a dimensional change ratio (MD/TD) of 0.21/0.21. Using the above transparent conductive film and carrier film, a transparent conductive film laminate was obtained in the same manner as in Example 1. The obtained transparent conductive film laminate was subjected to the evaluations of (4) and (5) above. The results are shown in Table 1.

>Comparative example 3> In the same manner as in Example 1, a transparent conductive film was obtained. In addition, a carrier film was obtained in the same manner as in Example 1 except that a polycycloolefin film made by Zeon Corporation under the product name "ZEONOR (registered trademark)" (Tg: 160° C.) was used. The base film used in the production of the carrier film had an MIT count of 150, a folding endurance count of 63, and a dimensional change ratio (MD/TD) of 0.05/0.06. Using the above transparent conductive film and carrier film, a transparent conductive film laminate was obtained in the same manner as in Example 1. The obtained transparent conductive film laminate was subjected to the evaluations of (4) and (5) above. The results are shown in Table 1.

[Table 1]

>Evaluation> As is clear from Table 1, the transparent conductive thin film laminates of Examples of the present invention suppressed outgassing and curling. It is presumed that this can be achieved by making the carrier film contain a specific polycarbonate resin whose dimensional change rate is not more than a predetermined value when heated at 145° C. for 1 hour, and whose number of MITs is 500 or more. Industrial availability

The transparent conductive film laminate of the present invention is suitable for use in touch panels.

10: Transparent conductive film 11: Conductive layer 12: Index matching (IM) layer 13: Hard coating (HC) layer 14: Resin film 15: Anti-bonding hard coating (ABHC) layer 20: Carrier film 21: Adhesive layer 22: Base film 23: Anti-bonding hard coating (ABHC) layer 100: transparent conductive film laminate

Fig. 1 is a schematic cross-sectional view of a transparent conductive thin film laminate according to an embodiment of the present invention.

10: Transparent conductive film

11: Conductive layer

12: Index matching (IM) layer

13: Hard coating (HC) layer

14: Resin film

15: Anti-bonding hard coating (ABHC) layer

20: Carrier film

21: Adhesive layer

22: Base film

23: Anti-bonding hard coating (ABHC) layer

100: transparent conductive film laminate

Claims (3)

A transparent conductive film laminate, comprising: a conductive film, which includes a resin film and a conductive film; and a carrier film, which has a base film containing polycarbonate resin and an adhesive layer disposed on one side of the base film, and is temporarily bonded to the conductive film in a peelable state through the adhesive layer; the carrier film is laminated on the opposite side of the conductive film; the glass transition temperature (Tg) of the base film is 150° C. The dimensional shrinkage after minutes is 0.2% or less in the first direction and the second direction respectively, the first direction corresponds to the longitudinal direction during manufacture, and the second direction corresponds to the width direction during manufacture, and the number of times the base film is broken in the MIT test according to JIS P 8115 is more than 500 times. A transparent conductive thin film laminate as claimed in Claim 1, wherein the aforementioned polycarbonate resin is substantially formed of a structural unit represented by the following general formula (I) and a structural unit represented by the following general formula (II), and satisfies the following conditions (a) to (d), the structural unit represented by the following general formula (I) is derived from an aliphatic diol compound having an aliphatic hydrocarbon group bonded to a terminal hydroxyl group,

(In the general formula (I), Q represents a hydrocarbon group with a carbon number of 3 or more that may contain different kinds of atoms, and R ₁ to R ₄ independently represent groups selected from the group consisting of a hydrogen atom, an aliphatic hydrocarbon group with a carbon number of ₁ to 30, and an aromatic hydrocarbon group with a carbon number of 6 to ₂₀ , and n and m each independently represent an integer of 0 to 10; however, when Q does not contain an aliphatic hydrocarbon group bonded to a terminal hydroxyl group, n and m independently represent an integer of 1 to 10; and, R ₁ and R ₂ At least one, and at least one of R and R are respectively selected from the group consisting of hydrogen atoms and aliphatic hydrocarbon groups);

(In the general formula (II), R and _R independently represent a halogen atom, an alkyl group with ₁ to 20 carbons, an alkoxy group with 1 to 20 carbons, a cycloalkyl group with 6 to 20 carbons, an aryl group with 6 to 20 carbons, a cycloalkoxy group with 6 to 20 carbons, or an aryloxy group with 6 to 20 carbons, p and q represent integers from 0 to 4, and X represents a single bond or a group selected from the group of divalent organic groups shown in the following general formula (II'));

(In the general formula (II'), R ₃ and R ₄ independently represent a hydrogen atom, an alkyl group with 1 to 10 carbons or an aryl group with 6 to 10 carbons, and R ₃ and R ₄ can also be bonded to form an aliphatic ring); (a) has the structure shown in the following general formula (III):

(In the general formula (III), k represents an integer of 4 or more, i represents an integer of 1 or more, l represents an integer of 1 or more, k' represents an integer of 0 or 1, and R represents a straight-chain or branched hydrocarbon group, a phenyl group or a hydrogen atom that may contain fluorine; however, in the aforementioned total amount of resin, more than 70% by weight is i=1); (b) the ratio of the structural unit shown in the aforementioned general formula (I) to the structural unit shown in the general formula (II) is 1 to 30: 99 to 70 (molar ratio) %; (c) weight average The molecular weight (Mw) is 30,000~100,000; (d) relative to the total amount of structural units constituting the aforementioned polycarbonate resin, the structural units represented by the following general formulas (1) and (2) contain 2000 ppm or less in terms of bisphenolic acid conversion value, general formula (1):

General formula (2):

(X in the above-mentioned general formulas (1) and (2) is the same as X in the general formula (II)). The transparent conductive film laminate according to claim 1 or 2, wherein the thickness of the aforementioned carrier film is 15 μm to 100 μm.

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