JP2009187687A - Method of manufacturing transparent conductive film, touch panel which has film obtained by the method, and display device which has the touch panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a transparent conductive film in which a crystallized transparent conductive layer can be formed on a base material film, which has high strength, and is superior in mechanical durability, to provide a touch panel having the film obtained by this method, and to provide a display device having this touch panel. <P>SOLUTION: This is the method of manufacturing the transparent conductive film in which in a state that the base material film having a cyclic olefin based polymer of a glass transition temperature of 130°C or more is heated to 100°C or more and the temperature obtained by subtracting 20°C from the glass transition temperature or less, the transparent conductive layer is formed by a sputtering method. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing a transparent conductive film having basic characteristics such as low birefringence, low moisture absorption, high transparency, and high heat resistance, a touch panel having a film obtained by this method, and a display having the touch panel Relates to the device.

When touched with a finger or drawn with a special pen, the resistive touch panel, in which the part comes in contact with the facing electrode and is energized to input signals, is advantageous for miniaturization, light weight, and thinning. Widely used as an input device for home appliances and portable terminals.
As shown in FIG. 2, the resistive touch panel has an upper portion formed by forming a transparent conductive layer 14 on a polymer film 11 on a lower electrode 1 formed by forming a transparent conductive layer 13 on a glass plate 10. The electrode 2 is laminated through the spacer 15 so that the transparent conductive layers 13 and 14 face each other. When the display surface of the upper electrode 2 is pushed with a finger or a pen, the upper electrode 2 and the lower electrode 1 are brought into contact with each other. And energized to input a signal. A hard coat layer 12 is provided on the surface of the upper electrode 2 to protect the polymer film 11.

Conventionally, the transparent conductive layer of a touch panel is generally formed by DC sputtering. In such a touch panel, the transparent conductive layer of the upper electrode and the transparent conductive layer of the lower electrode repeat contact and non-contact with input with a finger or a pen. Since transparent conductive materials such as ITO (indium tin oxide) have low scratch resistance, cracks are likely to occur in the transparent conductive layer of the upper electrode that undergoes repeated deformation, particularly during touch panel input. In addition, there is a problem that the transparent conductive layer is easily peeled off from the polymer film as the base material when the transparent conductive layers of the same material are in contact or non-contact with each other.
If the transparent conductive layer of the upper electrode is damaged or peeled off, the electrical resistance value of the transparent conductive layer will change, and its uniformity will be lost, and the electrical characteristics will be impaired. This could impair the reliability of the touch panel, causing damage, defects, and a decrease in durability.

  For the purpose of improving the durability of a transparent conductive film for touch panel use, Japanese Patent Application Laid-Open No. 2-194943 discloses that after forming an ITO film, heat treatment (annealing) is performed to crystallize the ITO. Are listed. That is, when an ITO film is formed on a resin substrate such as a polymer film by sputtering, the substrate cannot be heated during the film formation, so the formed ITO transparent conductive layer is in an amorphous state. Amorphous films have low strength and cannot be used for applications that require mechanical durability. For this reason, it has been proposed to increase the film strength by annealing and crystallizing the formed ITO film, but it is relatively low when the substrate of the transparent conductive film is a polymer film. There was a problem in terms of productivity and cost because annealing for a long time at temperature was required.

Japanese Patent Laid-Open No. 2-194943

  The present invention has been made to solve the above-described problems in the prior art, and is a method capable of producing a transparent conductive film having high strength and excellent mechanical durability, obtained by this method. It aims at providing the touchscreen manufactured using a film, and the display apparatus which has this touchscreen.

In the method for producing a transparent conductive film of the present invention, a substrate film having a cyclic olefin polymer having a glass transition temperature of 130 ° C. or higher is heated to a temperature of 100 ° C. or higher and the glass transition temperature of −20 ° C. or lower. The transparent conductive layer is formed by sputtering.
In the production method of the present invention, the base film is preferably a laminated film having a cyclic olefin polymer film and a hard coat layer.
The touch panel according to the present invention is characterized in that the transparent conductive film obtained by the above method is manufactured as at least one transparent electrode.
A display device according to the present invention has the touch panel described above on the display surface side.

ADVANTAGE OF THE INVENTION According to this invention, the transparent conductive film which ensured basic characteristics, such as low birefringence, low moisture absorption, high transparency, high heat resistance, and mechanical durability, can be provided.
According to the present invention, by laminating a transparent conductive layer on the hard coat layer, all of the above characteristics are satisfied, and particularly when used as a transparent electrode for a touch panel, a clear image is obtained and durable. A conductive transparent film having excellent properties can be provided.
Furthermore, according to the present invention, low birefringence, low moisture absorption, high transparency, high heat resistance, mechanical durability, etc. are excellent, and transparency is ensured. To provide a touch panel and a display device that can effectively display Newton's ring while preventing display unevenness, and exhibit a satisfactory image clarity that prevents the phenomenon of image flickering and glare to obtain a clear image. Can do.

Hereinafter, the manufacturing method of the transparent conductive film which concerns on this invention is demonstrated concretely.
In the method for producing a transparent conductive film according to the present invention, a base film having a cyclic olefin polymer having a glass transition temperature of 130 ° C. or higher is heated to a temperature of 100 ° C. or higher and the glass transition temperature of −20 ° C. or lower. In this state, a transparent conductive layer is formed by sputtering.
Examples of the base film used in the present invention include a cyclic olefin polymer film or a laminated film of a cyclic olefin polymer film and a hard coat layer. Among them, a cyclic olefin polymer film and a hard coat are particularly preferable. Laminated films with layers are preferred.

[Cyclic olefin polymer]
The cyclic olefin polymer forming the base film used in the present invention is obtained by ring-opening polymerization or addition polymerization of a monomer having a norbornene structure and another polymerizable monomer added as necessary. A polymer that is obtained and is preferably a polymer containing at least one repeating unit derived from a cyclic olefin compound represented by the following formula (1) (hereinafter also referred to as “specific monomer”). Since a cyclic olefin polymer having excellent heat resistance is used for the base film, sputtering can be performed at a high temperature, and a transparent conductive layer having high crystallinity can be formed.

(In the formula (1), R ^{1 to} R ⁴ each independently represent a hydrogen atom; a halogen atom; or a monovalent organic group that may contain oxygen, nitrogen, sulfur or silicon.
R ¹ and R ² , or R ³ and R ⁴ may be bonded to each other to form an alkylidene group, or R ¹ and R ² , R ³ and R ⁴ , or R ² and R ³ May combine with each other to form a monocyclic or polycyclic carbocyclic or heterocyclic ring. x represents 0 or 1, and y represents an integer of 0 to 3. )

Examples of the cyclic olefin polymer suitably used in the present invention include the following (co) polymers.
(A) A ring-opening (co) polymer of a specific monomer and, if necessary, another cycloolefin such as cycloalkene.
(B) A hydrogenated (co) polymer of the ring-opening (co) polymer of (a) above.
(C) Addition (co) polymers of the specific monomer and, if necessary, other cycloolefins, α-olefins and the like, and hydrogenated (co) polymers thereof.
Of these, (b) a hydrogenated (co) polymer of a ring-opening (co) polymer is particularly preferred from the viewpoint of optical properties and processability.

Specific examples of the specific monomer include the following compounds, but the present invention is not limited to these specific examples.
Bicyclo [2.2.1] hept-2-ene,
Tricyclo [4.3.0.1 ^2,5 ] -8-decene,
Tricyclo [4.4.0.1 ^2,5 ] -3-undecene,
Tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
Pentacyclo [6.5.1.1 ^3,6 . 0 ^2,7 . 0 ^9,13 ] -4-pentadecene,
5-methylbicyclo [2.2.1] hept-2-ene,
5-ethylbicyclo [2.2.1] hept-2-ene,
5-methoxycarbonylbicyclo [2.2.1] hept-2-ene,
5-methyl-5-methoxycarbonylbicyclo [2.2.1] hept-2-ene,
5-cyanobicyclo [2.2.1] hept-2-ene,
8-methoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-ethoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-n-propoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-isopropoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-n-butoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-methyl-8-methoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-methyl-8-ethoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-methyl-8-n-propoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-methyl-8-isopropoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-methyl-8-n-butoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
5-ethylidenebicyclo [2.2.1] hept-2-ene,
8-ethylidenetetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
5-phenylbicyclo [2.2.1] hept-2-ene,
8-phenyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
5-fluorobicyclo [2.2.1] hept-2-ene,
5-fluoromethylbicyclo [2.2.1] hept-2-ene,
5-trifluoromethylbicyclo [2.2.1] hept-2-ene,
5-pentafluoroethylbicyclo [2.2.1] hept-2-ene,
5,5-difluorobicyclo [2.2.1] hept-2-ene,
5,6-difluorobicyclo [2.2.1] hept-2-ene,
5,5-bis (trifluoromethyl) bicyclo [2.2.1] hept-2-ene,
5,6-bis (trifluoromethyl) bicyclo [2.2.1] hept-2-ene,
5-methyl-5-trifluoromethylbicyclo [2.2.1] hept-2-ene,
5,5,6-trifluorobicyclo [2.2.1] hept-2-ene,
5,5,6-tris (fluoromethyl) bicyclo [2.2.1] hept-2-ene,
5,5,6,6-tetrafluorobicyclo [2.2.1] hept-2-ene,
5,5,6,6-tetrakis (trifluoromethyl) bicyclo [2.2.1] hept-2-ene,
5,5-difluoro-6,6-bis (trifluoromethyl) bicyclo [2.2.1] hept-2-ene,
5,6-difluoro-5,6-bis (trifluoromethyl) bicyclo [2.2.1] hept-2-ene,
5,5,6-trifluoro-5-trifluoromethylbicyclo [2.2.1] hept-2-ene,
5-fluoro-5-pentafluoroethyl-6,6-bis (trifluoromethyl) bicyclo [2.2.1] hept-2-ene,
5,6-difluoro-5-heptafluoro-iso-propyl-6-trifluoromethylbicyclo [2.2.1] hept-2-ene,
5-chloro-5,6,6-trifluorobicyclo [2.2.1] hept-2-ene,
5,6-dichloro-5,6-bis (trifluoromethyl) bicyclo [2.2.1] hept-2-ene,
5,5,6-trifluoro-6-trifluoromethoxybicyclo [2.2.1] hept-2-ene,
5,5,6-trifluoro-6-heptafluoropropoxybicyclo [2.2.1] hept-2-ene,
8-fluorotetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-fluoromethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-difluoromethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-trifluoromethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-pentafluoroethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,8-difluorotetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,9-difluorotetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,8-bis (trifluoromethyl) tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,9-bis (trifluoromethyl) tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-methyl-8-trifluoromethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,8,9-trifluorotetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,8,9-tris (trifluoromethyl) tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,8,9,9-tetrafluorotetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,8,9,9-tetrakis (trifluoromethyl) tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,8-difluoro-9,9-bis (trifluoromethyl) tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,9-difluoro-8,9-bis (trifluoromethyl) tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,8,9-trifluoro-9-trifluoromethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,8,9-trifluoro-9-trifluoromethoxytetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,8,9-trifluoro-9-pentafluoropropoxytetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-fluoro-8-pentafluoroethyl-9,9-bis (trifluoromethyl) tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,9-difluoro-8-heptafluoroiso-propyl-9-trifluoromethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-chloro-8,9,9-trifluorotetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,9-dichloro-8,9-bis (trifluoromethyl) tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8- (2,2,2-trifluoroethoxycarbonyl) tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-methyl-8- (2,2,2-trifluoroethoxycarbonyl) tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene. These can be used alone or in combination of two or more.

Among the specific monomers, in the above formula (1), R ¹ and R ³ are each a hydrogen atom or a hydrocarbon group having 1 to 10, more preferably 1 to 4, particularly preferably 1 to 2 carbon atoms. R ² and R ⁴ are a hydrogen atom or a monovalent organic group, at least one of R ² and R ⁴ represents a polar group having a polarity other than a hydrogen atom and a hydrocarbon group, and x is 0 or 1 and y are integers of 0 to 3, more preferably x + y = 0 to 4, more preferably 0 to 2, particularly preferably x = 0 and y = 1. The specific monomer where x = 0 and y = 1 is preferable in that the cyclic olefin polymer obtained has a high glass transition temperature and excellent mechanical strength.

  Examples of the polar group of the specific monomer include a carboxyl group, a hydroxyl group, an alkoxycarbonyl group, an allyloxycarbonyl group, an amino group, an amide group, and a cyano group. These polar groups are connected via a linking group such as a methylene group. May be combined. In addition, a hydrocarbon group in which a divalent organic group having a polarity such as a carbonyl group, an ether group, a silyl ether group, a thioether group, or an imino group is bonded as a linking group can also be exemplified. Among these, a carboxyl group, a hydroxyl group, an alkoxycarbonyl group or an allyloxycarbonyl group is preferable, and an alkoxycarbonyl group or an allyloxycarbonyl group is particularly preferable.

Furthermore, a monomer in which at least one of R ² and R ⁴ is a polar group represented by the formula — (CH ₂ ) _n COOR is a high cyclic transition olefin polymer obtained, a high glass transition temperature, a low hygroscopicity, It is preferable at the point which has the outstanding adhesiveness with material. In the formula relating to the specific polar group, R is a hydrocarbon group having 1 to 12 carbon atoms, more preferably 1 to 4, particularly preferably 1 to 2, and preferably an alkyl group. In addition, n is usually 0 to 5, but the smaller the value of n, the higher the glass transition temperature of the obtained cyclic olefin polymer, which is preferable, and the specific monomer in which n is 0 is It is preferable in that the synthesis is easy.

In the above formula (1), R ¹ or R ³ is preferably an alkyl group, preferably an alkyl group having 1 to 4 carbon atoms, more preferably an alkyl group having 1 to 2 carbon atoms, particularly preferably a methyl group. In particular, it is obtained that the alkyl group is bonded to the same carbon atom as the carbon atom to which the specific polar group represented by the formula — (CH ₂ ) _n COOR is bonded. This is preferable in that the hygroscopicity can be lowered.

The preferred molecular weight of the cyclic olefin polymer used in the present invention, 0.2~5dl / g in intrinsic viscosity [η] _inh, more preferably 0.3~3dl / g, particularly preferably 0.4 to 1. The polystyrene-reduced number average molecular weight (Mn) measured by gel permeation chromatography (GPC) is 8,000 to 100,000, more preferably 10,000 to 80,000, and particularly preferably 12. Having a weight average molecular weight (Mw) of 20,000 to 300,000, more preferably 30,000 to 250,000, particularly preferably 40,000 to 200,000. Is preferred. Inherent viscosity [η] _inh , number average molecular weight and weight average molecular weight are in the above ranges, the heat resistance, water resistance, chemical resistance, mechanical properties of the cyclic olefin polymer, and the antiglare film of the present invention The balance with the stability of optical characteristics when used is good.

  The glass transition temperature (Tg) of the cyclic olefin polymer used in the present invention is 130 ° C. or higher, preferably 130 to 250 ° C., particularly preferably 140 to 200 ° C. A high glass transition temperature is required in order to stabilize the change in optical properties of the obtained cyclic olefin polymer film and prevent thermal deterioration of the resin when heated and processed in the vicinity of Tg such as stretching. Moreover, there exists an advantage that the moldability of a film is excellent in glass transition temperature being 250 degrees C or less.

  The saturated water absorption rate at 23 ° C. of the cyclic olefin polymer used in the present invention is preferably 2% by weight or less, more preferably 0.01 to 2% by weight, and particularly preferably 0.1 to 1% by weight. is there. If the saturated water absorption is within this range, the optical characteristics are uniform, the adhesion between the obtained cyclic olefin polymer film and other optical members and adhesives is excellent, and peeling or the like may occur during use. In addition, it is excellent in compatibility with an antioxidant and the like, and can be added in a large amount. The saturated water absorption is a value obtained by immersing in 23 ° C. water for 1 week and measuring the increased weight according to ASTM D570.

The cyclic olefin polymer used in the present invention has a photoelastic coefficient (C _P ) of 0 to 100 (× 10 ⁻¹² Pa ⁻¹ ) and a stress optical coefficient (C _R ) of 1,500 to Those satisfying 4,000 (× 10 ⁻¹² Pa ⁻¹ ) are preferably used. Here, for the photoelastic coefficient (C _P ) and the stress optical coefficient (C _R ), various documents (Polymer Journal, Vol. 27, No, 9pp 943-950 (1995), Journal of the Japan Rheological Society, Vol. 19 No. 2, p93-97 (1991), photoelasticity experiment method, Nikkan Kogyo Shimbun, Ltd., 7th edition of 1975. The former shows the degree of phase difference caused by stress in the glassy state of the polymer. On the other hand, the latter represents the degree of occurrence of the phase difference due to the stress in the flow state.
The large photoelastic coefficient (C _P ) is generated from an external factor or a strain generated from its own frozen strain when the cyclic olefin polymer film is used in combination with another optical member or an adhesive. Indicates that the optical characteristics change sensitively due to stress, etc. For example, when a protective layer is laminated as in the present invention, and when it is used fixed to other optical members, residual strain at the time of bonding It means that an unnecessary phase difference is likely to be generated due to a minute stress generated by shrinkage of a material accompanying a temperature change or a humidity change. Therefore, it is better that the photoelastic coefficient (C _P ) is as small as possible.
On the other hand, a large stress optical coefficient (C _R ) means that, for example, a desired retardation can be obtained with a small draw ratio when imparting the retardation to a cyclic olefin polymer film, or a large amount. There is a great merit that it is easy to obtain a film capable of imparting a phase difference, and when the same phase difference is desired, the film can be thinned as compared with a film having a small stress optical coefficient (C _R ).
From the above viewpoint, the photoelastic coefficient (C _P ) is preferably 0 to 100 (× 10 ⁻¹² Pa ⁻¹ ), more preferably 0 to 80 (× 10 ⁻¹² Pa ⁻¹ ), and particularly preferably 0. To 50 (× 10 ⁻¹² Pa ⁻¹ ), more preferably 0 to 30 (× 10 ⁻¹² Pa ⁻¹ ), and most preferably 0 to 20 (× 10 ⁻¹² Pa ⁻¹ ). Minimize unnecessary phase difference due to stress generated when the protective layer is laminated, stress generated when the antiglare film is fixed to other optical members, phase change caused by environmental changes during use, etc. It is to stop.

The cyclic olefin polymer used in the present invention may be added with known antioxidants, ultraviolet absorbers and the like. Moreover, additives such as a lubricant may be added for the purpose of improving processability.

The cyclic olefin polymer film used in the present invention is obtained by molding the above cyclic olefin polymer into a film or a sheet by a known method such as a melt molding method or a solution casting method (solvent casting method). Can be used.
The thickness of the cyclic olefin polymer film used in the present invention is usually 1 to 500 μm, preferably 1 to 300 μm, more preferably 10 to 250 μm, and particularly preferably 50 to 200 μm. This is to ensure good handling and facilitate winding into a roll.
The thickness distribution of the transparent film (cyclic olefin polymer film) used in the present invention is usually within ± 20% of the average value, preferably within ± 10%, more preferably within ± 5%, particularly preferably. Within ± 3%. The thickness variation per 1 cm is usually 10% or less, preferably 5% or less, more preferably 1% or less, and particularly preferably 0.5% or less. By performing such thickness control, unevenness in the film plane can be prevented.

As the transparent film used for the conductive transparent film of the present invention, a film stretched as necessary is suitably used. Specifically, it can be produced by a known uniaxial stretching method or biaxial stretching method. That is, a horizontal uniaxial stretching method by a tenter method, a compression stretching method between rolls, a longitudinal uniaxial stretching method using rolls having different circumferences, a biaxial stretching method in which horizontal uniaxial and longitudinal uniaxial are combined, a stretching method by an inflation method, etc. Can be used.
In the case of the uniaxial stretching method, the stretching speed is usually 1 to 5,000% / min, preferably 50 to 1,000% / min, more preferably 100 to 1,000% / min, Particularly preferred is 100 to 500% / min.
In the case of the biaxial stretching method, stretching may be performed in two directions at the same time, or the stretching may be performed in a direction different from the first stretching direction after uniaxial stretching. In these cases, the intersecting angle of the two stretching axes is usually in the range of 120 to 60 degrees. The stretching speed may be the same or different in each stretching direction, and is usually 1 to 5,000% / min, preferably 50 to 1,000% / min, and more preferably Is from 100 to 1,000% / min, particularly preferably from 100 to 500% / min.

The stretching temperature is not particularly limited, but is usually Tg ± 30 ° C., preferably Tg ± 10 ° C., more preferably Tg-5, based on the glass transition temperature (Tg) of the cyclic olefin polymer. It is the range of -Tg + 10 degreeC. Within the above range, it is possible to suppress the occurrence of phase difference unevenness, and control of the refractive index ellipsoid is facilitated, which is preferable.
The draw ratio is not particularly limited because it is determined by desired properties, but is usually 1.01 to 10 times, preferably 1.1 to 5 times, and more preferably 1.1 to 3.5 times. When the draw ratio exceeds 10 times, it may be difficult to control the phase difference.
The stretched film may be cooled as it is, but it should be allowed to stand in a temperature atmosphere of Tg-20 ° C. to Tg for at least 10 seconds, preferably 30 seconds to 60 minutes, more preferably 1 minute to 60 minutes. Is preferred. Thereby, the retardation film which consists of a cyclic olefin polymer film with little change with the passage of time of the retardation characteristics is obtained.

[Hard coat layer]
The base film used in the present invention may have a hard coat layer in advance on the surface on which the transparent conductive layer is laminated. The hard coat layer avoids deterioration of the visibility as a transparent conductive layer laminate due to scratches on the surface of the cyclic olefin polymer film during the formation of the transparent conductive layer, subsequent processing or assembly of the device. For that purpose, it is preferable to disperse and contain fine particles.

  The hard coat treatment can be performed on both sides or one side of the film before or after the formation of the transparent conductive layer. In the present invention, the hard coat treatment can be formed on both sides of the optical film before the formation of the transparent conductive layer. preferable. As the hard coat layer, a hard coat treatment agent having an antiglare action in which fine particles are dispersed in an active energy ray curable resin such as a melamine resin, a urethane resin, an alkyd resin, an acrylic resin, or a silicon resin. A cured coating is preferably used. Among the active energy ray-curable resins, acrylic resins are most preferably used because they also have an effect of improving the adhesion of the transparent conductive layer.

  The fine particles to be mixed with the hard coat treatment agent are not particularly limited, but those having an average particle diameter (primary average particle diameter) of, for example, about 1 nm to 100 nm, about 1 nm to 50 nm, and further about 1 nm to 25 nm. It is appropriate to use as a main component. In addition to this, a composition for forming a protective layer by using particles of a group having a different particle size from the particles added as the main component, such as those having an average particle size of about 50 nm to 800 nm or about 100 nm to 10 μm It is also preferable to prepare the product. By having such an average particle size, partial display unevenness such as white blurring and / or black floating or unclear display of background image, non-uniform display such as glare and / or glare, light of Newton ring It is possible to eliminate the three main types of interference effects in a well-balanced manner.

The fine particles used here are preferably silica particles or polymer particles. Examples of silica include colloidal silica and fumed silica. Fumed silica as used herein refers to high purity (99) having the smallest particle size produced on an industrial scale (average primary particle size is 7 to 40 nm, specific surface area is 50 to 380 m ² / g). 0.9% or higher) anhydrous silica, which is usually produced by a hydrolysis process in an oxygen / hydrogen burner of silicon tetrachloride at a high temperature of 1000 ° C. or higher.
As the silica, those obtained by subjecting the surface silanol groups to hydrophobic treatment can be used, and those obtained by hydrophobic treatment are preferable.
The mixing ratio of the silica particles is preferably such that the silica particles are 0.1 to 10 parts by weight with respect to 100 parts by weight of the resin. When the amount of silica particles is small, the antiglare effect is inferior.

  In forming the cured coating, a composition obtained by adding various additives such as an antistatic agent and a polymerization initiator to the above-mentioned active energy ray-curable resin and fine particles as necessary is usually diluted with a solvent. A solid content of 20 to 80% by weight is prepared, and this is applied to one surface of an optical film, such as a gravure coater, reverse coater, spray coater, slot orifice coater or screen printing, which is a general solution coating means. Thus, after coating so that the thickness after drying and curing is about 1 to 15 μm, it can be cured by ultraviolet irradiation or electron beam irradiation after heat drying. Prior to the formation of the hard coat treatment layer, the adhesion surface between the transparent film and the hard coat treatment layer is subjected to easy adhesion treatment such as corona discharge, ultraviolet irradiation, plasma treatment, sputter etching treatment, primer treatment, etc. Can be further enhanced.

[Method for forming transparent conductive layer]
The transparent conductive layer according to the present invention is a layer having transparency in the visible light region and having conductivity. As the method for forming the transparent conductive layer, any of the conventionally known techniques such as vacuum deposition, sputtering, and ion plating can be used, but from the viewpoint of film uniformity and adhesion of the thin film to the transparent substrate. The thin film formation by sputtering is preferred. The thin film material to be used is not particularly limited. For example, in addition to metal oxides such as indium oxide containing tin oxide, indium oxide containing titanium oxide, tin oxide containing antimony, gold, silver, Platinum, palladium, copper, aluminum, nickel, chromium, titanium, cobalt, tin, zinc, or alloys thereof are preferably used. Among them, indium oxide (ITO) containing tin oxide is preferable.

In the present invention, a base film (a cyclic olefin polymer film or a laminated film of a cyclic olefin polymer film and a hard coat layer) is heated to a temperature of 100 ° C. or more and Tg-20 ° C. or less of the cyclic olefin polymer. And a transparent conductive layer is formed by performing the process of sputtering. By forming the transparent conductive layer under such conditions, a crystallized transparent conductive layer can be obtained. A particularly preferable heating temperature is 140 to 150 ° C. When the heating temperature of the base film is lower than 100 ° C., a sufficiently crystallized transparent conductive layer cannot be obtained. Moreover, when it exceeds Tg-20 degreeC, there exists a possibility that a base film may be softened and deform | transformed or a phase difference may increase.
As a method of heating the base film, a method of heating the base film with infrared rays, and, in the roll-to-roll method, a method of heating the base film by heating the roll in contact with the base film Etc. are mentioned as a preferable method.

  The transparent conductive layer is formed, for example, in a pressure-resistant container that can maintain the inside in a vacuum state, and the film (base film) fed from the film roll is sent to the substrate support section via the delivery-side guide roller to support the substrate. It is preferable to carry out using the apparatus comprised so that the outer peripheral surface of a part may be wound and wound up by a winding roller via a winding side guide roller.

  When forming a transparent conductive layer, a conventionally well-known ITO target is used as a target. As a target material used for forming the ITO film, it is desirable to use a sintered body target having a weight ratio of indium oxide to tin oxide of 99: 1 to 90:10, more preferably 99: 1 to 95: 5. When a target having a tin oxide weight ratio of more than 10% by weight is used, an amorphous ITO film tends to be formed, and resistance to acid is weakened. An indium oxide target containing titanium oxide is also used.

Moreover, when a small amount of oxygen, preferably 0.1 to 3% by volume of O ₂ with respect to the total of Ar and O ₂ is introduced into Ar as an atmospheric gas during film formation, the transparency and conductivity of the ITO thin film are improved. This is preferable because it can be performed.
In the case of an atmosphere gas containing only Ar, or when O ₂ is more than the above range, the crystallization temperature of the produced ITO transparent conductive layer becomes high, which is not preferable. In addition, if O ₂ exceeds the above range, the resistance value of the deposited ITO thin film is remarkably increased, and the required conductivity cannot be obtained.

  The film thickness of this transparent conductive layer is generally about 10 to 100 nm, preferably 20 to 30 nm. If the film thickness of the transparent conductive layer is too thin, sufficient conductivity cannot be obtained, and even if it is excessively thick, there is no difference in conductivity, the film formation cost is high, and the transparent conductive film is thick. It is not preferable.

As shown in FIG. 1, the preferred structure of the touch panel of the present invention is a lower electrode 1 formed by forming a transparent conductive layer 13 on a glass plate 10 and hard coat layers 12 and 12 formed on both sides of a polymer film 11. Further, the upper electrode 2 formed by forming the transparent conductive layer 14 on one hard coat layer 12 is laminated through the spacer 15 so that the transparent conductive layers 13 and 14 face each other. A touch panel provided with such a transparent conductive film as an upper electrode has excellent durability and reliability because the mechanical durability of the transparent conductive layer is good.
In addition, although the transparent conductive film of this invention is suitable for the use as an upper electrode of a touch panel, it can be effectively used for a transparent switching device and other various optical system transparent conductive film uses.

EXAMPLES Hereinafter, although this invention is demonstrated further more concretely based on an Example, this invention is not limited to these Examples.
<Production Example 1>
(Preparation of hard coat treatment agent)
100 parts of urethane acrylate obtained from pentaerythritol acrylate and hydrogenated xylene diisocyanate, 20 parts of isocyanuric acid-tris [2- (acryloyloxy) ethyl], and silica particles having an average particle diameter of 1 to 3 μm in total solids 40% by weight, 3% by weight of the photopolymerization initiator 1-hydroxycyclohexyl phenyl ketone based on the total solid content, and a solid content concentration of a mixed solvent of butyl acetate / methyl ethyl ketone (1/2: weight ratio). A hard coat treatment agent was prepared by diluting to 45% by weight.

[Example 1]
Arton (registered trademark) film (manufactured by JSR Corporation, Tg: 165 ° C., film thickness), which is a transparent film made of a cyclic olefin polymer, by the gravure reverse method, using the hard coat treatment agent obtained in Production Example 1 188 μm, film width: 300 mm, film length: 30 m), dried at 70 ° C. for 40 seconds, and irradiated with 300 mJ / cm ² ultraviolet rays to obtain a film having a protective layer with a thickness of 1.7 μm. It was.
A protective layer was similarly formed on the surface opposite to the surface of the protective layer of the film having the protective layer, and a film having a protective layer with a thickness of 1.7 μm on both surfaces was formed. Thereafter, the surface of the film was subjected to plasma treatment at an Ar flow rate of 300 sccm and an output of 700 V / 0.05 A.
The film was placed in a sputtering apparatus, the roller was heated to 140 ° C. while evacuating, the pressure was maintained at 2 × 10 ⁻¹ Pa, and a target of In ₂ O ₃ / A transparent conductive layer made of ITO is laminated to a thickness of 200 Å on the surface of the film subjected to plasma treatment by sputtering using an oxide mixture of SnO ₂ = 90/10 (weight ratio). 1 was obtained.

When the sheet resistance value of the obtained transparent conductive film 1 was measured by a four-probe method, it was 400Ω / □, and 85 ° C. × 85% R.D. H. When the sheet resistance value was measured again after being stored for 250 hours in the presence of No. 1, the sheet resistance value was 500Ω, and the change in sheet resistance was small. Moreover, when the keystroke test was performed on the obtained transparent conductive film 1 using a 0.8R polyacetal pen under the conditions of a weight of 250 g and an applied voltage of 3 V, conductivity was obtained even after 3 million times. Showed sex.
Furthermore, when the crystallinity of ITO was confirmed about the obtained transparent conductive film 1 by the X-ray-diffraction measurement, the crystallinity peak was recognized by 2 (theta) = 30 degree, 35 degree, and 51 degree vicinity.

[Comparative Example 1]
As in Example 1, after forming protective layers on both sides of the transparent film and performing plasma treatment, the roller was not heated, and the pressure was 2 × 10 ⁻¹ Pa, 25 ° C. under conditions of argon gas and oxygen. By sputtering using an oxide mixture of In ₂ O ₃ / SnO ₂ = 90/10 (weight ratio) as a target under gas inflow, a transparent conductive layer made of ITO is thickened on the surface of the film subjected to plasma treatment. The transparent conductive film 2 was obtained by laminating at a thickness of 200 angstroms.
When the obtained transparent conductive film 2 was subjected to various evaluations in the same manner as in Example 1, the sheet resistance value was 450Ω / □, and 85 ° C. × 85% R.D. H. When the sheet resistance value was measured again after being stored for 250 hours in the presence of, the sheet resistance value increased to 1200 Ω / □. Moreover, when the keystroke test was done like Example 1 with respect to the obtained transparent conductive film 2, electroconductivity was no longer obtained by 800,000 times.
Furthermore, when the crystalline peak of ITO was confirmed by X-ray diffraction measurement of the obtained transparent conductive film 2, it was confirmed that the crystalline peak was not observed and was amorphous.

It is a schematic sectional drawing which shows the structure of a preferable touch panel in this invention. It is a schematic sectional drawing which shows the structure of a common touch panel.

Explanation of symbols

1 Lower electrode 2 Upper electrode
10 Glass plate
11 Polymer film
12 Hard coat layer
13 Transparent electrode layer
14 Transparent electrode layer
15 Spacer

Claims (4)

Forming a transparent conductive layer by sputtering in a state where a substrate film having a cyclic olefin polymer having a glass transition temperature of 130 ° C. or higher is heated to a temperature of 100 ° C. or higher and the glass transition temperature −20 ° C. or lower; A method for producing a transparent conductive film, which is characterized. The manufacturing method of the transparent conductive film of Claim 1 whose base film is a laminated | multilayer film which has a cyclic olefin type polymer film and a particle | grain containing hard coat layer. A touch panel manufactured using the transparent conductive film obtained by the method according to claim 1 as at least one transparent electrode. A display device comprising the touch panel according to claim 3 on a display surface side.

Images