JP5609926B2 - Transparent conductive film and low reflective touch panel using the same - Google Patents

Description

  The present invention relates to a transparent conductive film mainly used for a low reflection touch panel.

  Conventionally, a touch panel is arranged on the front surface of a liquid crystal display widely used in products such as a word processor, a notebook personal computer, and a PDA (personal digital assistant). The touch panel has a structure in which two transparent plates on which a transparent conductive film is formed are arranged so that the transparent conductive films face each other with a spacer between them. By pressing a part of the contact, it is brought into contact to be electrically conducted so that input can be performed. However, the touch panel has a problem that when the input operation is performed in a room with a fluorescent lamp or the like or outdoors, there is reflection of light from the outside on the transparent conductive film surface, so that the contrast of the display screen is remarkably lowered and it is very difficult to see. was there.

  Therefore, in order to solve such a problem, the first quarter-wave plate, the two transparent conductive films, the second quarter-wave plate, and the polarizing plate that are opposed to each other through a spacer in order from the liquid crystal display side. At least a touch panel is proposed. A circularly polarized antireflection filter is formed by the second quarter-wave plate and the polarizing plate, and the reflection of light incident from the outside on the transparent conductive film is efficiently cut (for example, see Patent Document 1). . The transparent conductive film that is not on the liquid crystal display side of the low-reflection touch panel with such a configuration is usually made by forming a transparent conductive film such as ITO on the optically isotropic film as a base material, The film is formed directly on the second quarter-wave plate.

  As the optically isotropic film, COP (cycloolefin polymer; hereinafter referred to as COP) and PC (polycarbonate; hereinafter referred to as PC) are often used (for example, see Patent Document 2). Moreover, as for the transparent conductive film by the side of a liquid crystal display, transparent conductive films, such as ITO, are normally formed on the glass plate. In addition, as the quarter wave plate, an optical isotropic film made of COP, PC, or the like is used as a retardation film by causing optical anisotropy by a method such as stretching.

However, the conventional production methods for the conventional COP or PC film “Arton” manufactured by JSR and “Essina” manufactured by Sekisui Chemical Co., Ltd. only employ film formation by the casting method, which is expensive to manufacture. The reason is that it is difficult to achieve low retardation, which is essential for optical isotropy, in the melt extrusion method with low production cost. In addition, there is a film by the COP melt extrusion method, such as “ZEONOR” manufactured by Nippon Zeon Co., Ltd., but there is a problem that retardation occurs due to orientation or stress of polymer bond chains during molding (for example, patents) Reference 3). Since the stability of the optimum manufacturing conditions is low, it takes time until a raw film satisfying the required performance is stably produced. As a result, there is a problem that the yield is low and the cost is high.
In order to disseminate the touch panel in the industry in this way, supply a low-cost, high-productivity film with a transparent conductive film that controls retardation and has a cost problem among its constituent members. Is desired.
Japanese Patent Laid-Open No. 10-48625 Japanese Patent Laid-Open No. 2004-5102 JP 2004-109355 A

  An object of the present invention is to provide a transparent conductive film that can control retardation and can be manufactured at low cost, and a low-reflection touch panel using the film.

  As a result of intensive research, the present inventors have found that a polyester resin comprising a dicarboxylic acid unit and a diol unit, and a polyester resin in which 1 to 80 mol% of the diol unit is a diol unit having a cyclic acetal skeleton by a melt extrusion method. It has been found that there is a relatively wide range of stable production conditions for the film, and in particular, it has been found that the retardation is controlled to be low by changing the temperature of the first cooling roll. Furthermore, it has also been found that an arbitrary retardation can be expressed by using the polyester film as a raw film (unstretched film) and stretching it.

  That is, the present invention relates to a polyester raw material obtained by forming a polyester resin, which is a diol unit having a cyclic acetal skeleton at 1 to 80 mol% in a polyester resin composed of a dicarboxylic acid unit and a diol unit, by a melt extrusion method. A transparent conductive film in which a transparent conductive film is formed on the substrate film, and the transparent conductive film, using the film or a film obtained by stretching the original film and expressing retardation as a substrate, were used. The present invention relates to a low reflection touch panel.

The raw film used as the base film of the transparent conductive film of the present invention has an extremely high production speed, remarkably excellent optical characteristics represented by the retardation, and a high retardation can be obtained by stretching at a low magnification. As a result, the Boeing phenomenon is less likely to occur, and the usable area can be increased, and an effect of providing a low-cost film with a high yield can be achieved. Therefore, by forming a transparent conductive film on the raw film or stretched film, it becomes possible to produce an inexpensive transparent conductive film with controlled retardation, and further manufacture an inexpensive low-reflection touch panel. can do.
In addition, since one sheet of optical isotropic film can be omitted by using a film obtained by forming a transparent conductive film on a quarter-wave plate produced by stretching to express a desired retardation, further A low-reflection touch panel can be manufactured at a low cost.

The present invention relates to a polyester raw film in which a polyester resin comprising a dicarboxylic acid unit and a diol unit, and a polyester resin in which 1 to 80 mol% of the diol unit is a diol unit having a cyclic acetal skeleton is formed by a melt extrusion method. Alternatively, a transparent conductive film in which a transparent conductive film is formed on the base film using a film obtained by stretching the original film and expressing retardation, and a touch panel using the transparent conductive film It is about.

  The ratio of the diol unit which has a cyclic acetal skeleton in the diol unit of the polyester resin used for this invention is 1-80 mol%. By including 1 mol% or more of diol units having a cyclic acetal skeleton, a decrease in crystallinity of the polyester resin and an increase in the glass transition temperature are achieved simultaneously, and the polyester film obtained from the resin has improved transparency and heat resistance. . In addition, the polyester film has improved processability such as the generation of whiskers during processing such as cutting and punching, and further reduced the retardation value, reduced unevenness of the retardation value, and unevenness in thickness during melt extrusion. The optical performance is improved such as reduction. On the other hand, when the ratio of the diol unit having a cyclic acetal skeleton in the polyester resin exceeds 80 mol%, the crystallinity of the polyester resin increases and the transparency of the resulting polyester film may decrease. On the other hand, if it is less than 1 mol%, the effect of lowering the crystallinity of the polyester resin and raising the glass transition temperature cannot be obtained sufficiently, which is not preferable. Therefore, the ratio of the diol unit having a cyclic acetal skeleton is preferably 1 to 80 mol%, more preferably 1 to 60 mol% from the viewpoint of heat resistance, transparency, processability, and optical performance of the polyester film. More preferably, it is 5-60 mol%, and especially 15-60 mol% is preferable.

The diol unit having a cyclic acetal skeleton in the diol structural unit of the polyester resin used in the present invention is represented by the general formula (1):
Or general formula (2):

The unit derived from the compound represented by these is preferable. In the general formulas (1) and (2), R ¹ and R ² are each independently an aliphatic hydrocarbon group having 1 to 10 carbon atoms, an alicyclic hydrocarbon group having 3 to 10 carbon atoms, and This represents a hydrocarbon group selected from the group consisting of aromatic hydrocarbon groups having 6 to 10 carbon atoms. R ¹ and R ² are preferably a methylene group, an ethylene group, a propylene group, a butylene group, or a structural isomer thereof. Examples of these structural isomers include an isopropylene group and an isobutylene group. R ³ is a carbon selected from the group consisting of an aliphatic hydrocarbon group having 1 to 10 carbon atoms, an alicyclic hydrocarbon group having 3 to 10 carbon atoms, and an aromatic hydrocarbon group having 6 to 10 carbon atoms. Represents a hydrogen group. R ³ is preferably a methyl group, an ethyl group, a propyl group, a butyl group, or a structural isomer thereof. Examples of these structural isomers include isopropyl group and isobutyl group. Examples of the compounds of the general formulas (1) and (2) include 3,9-bis (1,1-dimethyl-2-hydroxyethyl) -2,4,8,10-tetraoxaspiro [5.5] undecane ( Hereinafter, it may be denoted as SPG), 5-methylol-5-ethyl-2- (1,1-dimethyl-2-hydroxyethyl) -1,3-dioxane and the like are particularly preferable.

In addition, the diol constituent unit other than the diol unit having a cyclic acetal skeleton is not particularly limited, but ethylene glycol, trimethylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol. , Aliphatic diols such as diethylene glycol, propylene glycol and neopentyl glycol; 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 1,2-decahydronaphthalenediethanol, 1,3-decahydronaphthalene Methanol, 1,4-decahydronaphthalene diethanol, 1,5-decahydronaphthalene diethanol, 1,6-decahydronaphthalene diethanol, 2,7-decahydronaphthalene diethanol, tetralin dimethanol, norbornane Alicyclic diols such as methanol, tricyclodecane dimethanol and pentacyclododecane dimethanol; polyether compounds such as polyethylene glycol, polypropylene glycol and polybutylene glycol; 4,4 ′-(1-methylethylidene) bisphenol; Bisphenols such as methylene bisphenol (bisphenol F), 4,4′-cyclohexylidene bisphenol (bisphenol Z), 4,4′-sulfonylbisphenol (bisphenol S); alkylene oxide adducts of the bisphenols; hydroquinone, resorcin, Aromatic dihydroxy compounds such as 4,4′-dihydroxybiphenyl, 4,4′-dihydroxydiphenyl ether, 4,4′-dihydroxydiphenylbenzophenone; Alkylene oxide adducts of the diol units families dihydroxy compounds can be exemplified. Considering the mechanical strength, heat resistance, and availability of the diol of the polyester resin, diol units such as ethylene glycol, diethylene glycol, trimethylene glycol, 1,4-butanediol, and 1,4-cyclohexanedimethanol are preferable. Glycol units are particularly preferred.

The dicarboxylic acid structural unit of the polyester resin used in the present invention is not particularly limited, but succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, dodecanedicarboxylic acid, cyclohexane Dicarboxylic acid, decalin dicarboxylic acid, norbornane dicarboxylic acid, tricyclodecane dicarboxylic acid, pentacyclododecanedicarboxylic acid, 3,9-bis (1,1-dimethyl-2-carboxyethyl) -2,4,8,10-tetra Aliphatic dicarboxylic acid units such as oxaspiro [5.5] undecane, 5-carboxy-5-ethyl-2- (1,1-dimethyl-2-carboxyethyl) -1,3-dioxane, dimer acid; terephthalic acid , Isophthalic acid, phthalic acid, 2-methylterephthalic acid, 1,3 For aromatic dicarboxylic acids such as naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, biphenyldicarboxylic acid, tetralindicarboxylic acid, etc. Examples are derived units. Considering the mechanical strength and heat resistance of the polyester resin, a unit derived from an aromatic dicarboxylic acid is preferable, and considering the availability of the dicarboxylic acid, a unit derived from terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid Is particularly preferred. In addition, the dicarboxylic acid structural unit of a polyester resin may be comprised from 1 type, or may be comprised from 2 or more types.

The polyester resin used in the present invention includes units derived from monoalcohols such as butyl alcohol, hexyl alcohol, octyl alcohol and trimethylolpropane within the range that does not impair the purpose of the present invention in order to adjust melt viscoelasticity, molecular weight, etc. , Units derived from trihydric or higher polyhydric alcohols such as glycerin, 1,3,5-pentanetriol, pentaerythritol, units derived from monocarboxylic acids such as benzoic acid, propionic acid, butyric acid, trimellitic acid, pyro Units derived from polyvalent carboxylic acids such as merit acid, units derived from oxyacids such as glycolic acid, lactic acid, hydroxybutyric acid, 2-hydroxyisobutyric acid and hydroxybenzoic acid may also be included.

In view of moldability, heat resistance, mechanical performance, etc., particularly in the polyester resin used in the present invention, the diol unit having a cyclic acetal skeleton is 3,9-bis (1,1-dimethyl-2-hydroxyethyl) -2,4. , 8,10-tetraoxaspiro [5.5] undecane unit, the diol constituent unit other than the diol unit having a cyclic acetal skeleton is an ethylene glycol unit, the dicarboxylic acid constituent unit is a terephthalic acid unit, an isophthalic acid unit, And at least one dicarboxylic acid unit selected from 2,6-naphthalenedicarboxylic acid units. When the dicarboxylic acid structural unit is a 2,6-naphthalenedicarboxylic acid unit, the heat resistance and mechanical performance of the polyester resin are particularly easily improved.

The intrinsic viscosity of the polyester resin used in the present invention can be appropriately selected according to the molding method and application. In the polyester resin used in the present invention, a range of 0.5 to 1.5 dl / g as measured at 25 ° C. using a mixed solvent of phenol and 1,1,2,2-tetrachloroethane in a mass ratio of 6: 4. More preferably, it is 0.5-1.2 dl / g, More preferably, it is 0.6-1.0 dl / g. When the intrinsic viscosity is within this range, the polyester resin used in the present invention has an excellent balance between moldability and mechanical performance.

Although the glass transition temperature of the polyester resin used for this invention can be suitably selected according to a use, it is preferable that it is 85 degreeC or more, More preferably, it is 90 degreeC or more, Especially preferably, it is 94 degreeC or more. When the glass transition temperature is in the above range, the polyester film used in the present invention is excellent in heat resistance.

There is no restriction | limiting in particular in the method of manufacturing the polyester resin used for this invention, The manufacturing method of a conventionally well-known polyester resin can be applied. Examples thereof include a melt polymerization method such as a transesterification method and a direct esterification method, or a solution polymerization method. In the direct esterification method, after dicarboxylic acid is esterified with a diol having no cyclic acetal skeleton, it may be necessary to react with a diol having a cyclic acetal skeleton after reducing the acid value. Various catalysts such as transesterification catalysts, esterification catalysts, polycondensation catalysts, etc., etherification inhibitors, heat stabilizers, light stabilizers, and other stabilizers, polymerization regulators, and the like that are conventionally used may be used. These can be appropriately selected according to the reaction rate, the color tone of the polyester resin, safety, thermal stability, weather resistance, self-elution properties, and the like.

The polyester resins used in the present invention include antioxidants, light stabilizers, ultraviolet absorbers, plasticizers, extenders, matting agents, drying regulators, antistatic agents, antisettling agents, surfactants, flow improvers. Various additives such as drying oil, waxes, fillers, colorants, reinforcing agents, surface smoothing agents, leveling agents, curing reaction accelerators, thickeners, and molding aids can be added. Resin such as polyolefin resin, polyamide resin, acrylonitrile resin, vinyl chloride resin, vinyl acetate resin, acrylic resin, methacrylic resin, polystyrene, ABS resin, AS resin, polyimide resin, AS resin, polyester resin having no cyclic acetal skeleton Or these oligomers can also be added. These additives, resins, and oligomers may be added at the production stage of a polyester resin having a cyclic acetal skeleton or a polyester resin or polycarbonate resin not having a cyclic acetal skeleton to be blended, or may be added after the production. . Moreover, you may add at the time of shaping | molding.

Next, the polyester raw film used in the present invention will be described. Examples of the method for forming a film of the polyester resin include a melt extrusion method and a solution casting method. In the present invention, the melt extrusion method is used from the balance between economic efficiency and film performance.

The melt extrusion method will be further described in detail. The polyester raw film used in the present invention can be formed using a conventionally known method. Examples of the melt extrusion method include a T-die extrusion method and an inflation method. The T-die extrusion method is desirable from the viewpoint of obtaining an optically isotropic film. As an apparatus for melting the polyester resin, a generally used extruder may be used, and a single-screw extruder or a multi-screw extruder may be used. The extruder may have one or more vents, and may remove moisture, low-molecular substances, etc. from the molten resin by reducing the vents. Moreover, you may provide a metal-mesh filter, a sintered filter, and a gear pump as needed at the front-end | tip or downstream side of an extruder. As the die, a T die, a coat hanger die, a fish tail die, a stack plate die, or the like can be used.

The extrusion temperature is preferably 200 to 300 ° C, more preferably 210 to 280 ° C, and particularly preferably 220 to 270 ° C. When the extrusion temperature is within the above range, the resulting polyester raw film is excellent in the balance of optical isotropy, smoothness, transparency, color tone, mechanical properties and the like.

A conventionally known method can be used as a method for cooling the molten resin extruded from the die. In general, it can be cooled by a cooling drum. Since the polyester resin used in the present invention is a substantially amorphous resin, the temperature of the cooling drum can be set widely. In order to obtain an optically isotropic optical film, the temperature of the cooling drum is preferably 30 ° C. above and below the glass transition temperature of the polyester resin, more preferably 20 ° C. above and below the glass transition temperature of the polyester resin, particularly preferably. It is 10 ° C. above and below the glass transition temperature of the polyester resin. In order to obtain an optically isotropic optical film, it is preferable to control the discharge speed, the take-up speed, and the temperature of the cooling drum according to the apparatus so that the film is not substantially stretched.

The in-plane retardation at a wavelength of 550 nm of the polyester raw film used in the present invention is preferably 20 nm or less, more preferably 15 nm or less, still more preferably 10 nm or less, and particularly preferably 5 nm or less. When it exists in the said range, the polyester raw fabric film used for this invention can be used suitably for the base material of the transparent conductive film used for a low reflection touch panel. Moreover, the stretched film which stretched the polyester raw film used for this invention and controlled the in-plane retardation can be used suitably for the base material of the transparent conductive film to which the phase difference used for a low reflective touch panel was provided.

The thickness of the polyester raw film can be arbitrarily set according to the required specifications. The thinner the retardation film is, the better from the viewpoint of reducing the weight of the liquid crystal display device. However, the thickness of the polyester raw film is desirably 20 to 200 μm because of restrictions on the melt extruder.

The total light transmittance of the polyester raw film used in the present invention is preferably 85% or more, more preferably 90% or more. Moreover, it is preferable that a haze is 3% or less, More preferably, it is 2% or less. When these values are in the above range, the performance becomes sufficient as a raw film of a transparent conductive film used for a low reflection touch panel.

Next, the stretching method for the polyester raw film will be described in detail. The original film can be stretched by uniaxial stretching, sequential biaxial stretching, or simultaneous biaxial stretching. To produce a quarter-wave plate or a half-wave plate for a low-reflection touch panel, Uniaxial stretching is used. FIG. 5 shows experimental results of stretching temperature and in-plane retardation in uniaxial stretching of a polyester raw film having an SPG copolymerization rate of 45%. However, this data is specific to a stretching apparatus represented by orientation relaxation due to heat and time until the film is taken out after stretching, and the data obtained in another stretching apparatus may be slightly different. Based on such data, it is possible to obtain a retardation film having a desired in-plane retardation. The stretching temperature is in the range from the resin glass transition temperature to the melting point. The higher the stretching temperature, the lower the in-plane retardation at the same stretching ratio can be controlled.
In the case of biaxial stretching, longitudinal and lateral stretching are performed simultaneously or sequentially. However, when producing a quarter wavelength plate or a half wavelength plate, the degree of orientation by stretching either axis should be increased. It is realized by. Since in-plane retardation is a phase difference between the vertical and horizontal directions, it is determined by the difference in absolute value of the in-plane main refractive index. However, in this case, even if the in-plane retardation is the same, the relationship with the main refractive index perpendicular to the surface is different. Thus, the three-dimensional refractive index relative relationship determines the incident angle dependence characteristic of the retardation of the wave plate, and there are various design guidelines in view of the viewing angle characteristic of the wave plate. In this example, uniaxial stretching will be described, but the present invention is not limited to this.

The quarter-wave plate used for the low-reflection touch panel needs to have an in-plane retardation of λ / 4 (nm) in the visible light wavelength band, and a half-wave plate and a quarter wavelength at a wavelength of 550 nm. A broadband circularly polarizing plate can be obtained by laminating the slow axes of the plates so as to intersect each other (see JP-A-10-068816).

The transparent conductive film of the present invention can be produced by forming a transparent conductive film on at least one side of a polyester raw film. Further, by stretching the polyester raw film uniaxially at a predetermined temperature and magnification, the in-plane retardation is in a range of 100 to 175 nm at a wavelength of 550 nm which is a central wavelength of 350 to 750 nm which is a visible light wavelength region (preferably It is also possible to form a transparent conductive film on at least one surface of a controlled polyester stretched film (in the range of 132.5 to 142.5 nm) (a quarter wavelength plate). Further, in order to make the phase difference λ / 4 (nm) over the visible light wavelength region, the in-plane retardation is controlled in the range of 200 to 350 nm (preferably in the range of 270 to 280 nm) by uniaxial stretching. The stretched laminated film (1/2 wavelength plate) is laminated on the 1/4 wavelength plate side of the stretched laminated film obtained by laminating the polyester stretched film (1/4 wavelength plate) with each slow axis intersected by about 60 °. It is also possible to form a transparent conductive film on the surface. As described above, a transparent conductive film having optical isotropy and a transparent conductive film having the function of a quarter wavelength plate can be produced at low cost.

Specifically, the transparent conductive film can be formed by a well-known sputtering method using ITO (Indium Tin Oxide) or IZO (Indium Zinc Oxide). In particular, for film formation on a resin film having a low glass transition temperature, it is preferable to use an IZO target that can be formed at a low temperature. Alternatively, a conductive polymer may be applied to form a film. Examples of the conductive polymer include polythiophene-based and polyaniline-based polymers.
Thus, the produced transparent conductive film can be made into the structural member of a low-reflection touch panel.

The essence of the touch panel is a mechanism in which two transparent conductive films facing each other while maintaining a gap are used as electrodes and are brought into contact with each other by pressing, and are arranged on the front surface of the liquid crystal display. When a polarizing plate and a quarter-wave plate are arranged on the outer surface side of the transparent conductive film, external light entering through the transparent film is reflected by the transparent conductive film and passes through the quarter-wave plate in reverse. Since it is blocked by the plate, it becomes a low-reflection touch panel. In order to pass light emitted from the liquid crystal display surface, a quarter wavelength plate is disposed between the liquid crystal display surface and the transparent conductive film.
A low-reflection touch panel essentially consists of these elements, but in order to actually realize the operation of the touch panel, a member that supports a transparent conductive film, a coating material, a spacer that forms a gap, and the like are used. The member supporting the transparent conductive film requires controlled optical characteristics, and the polyester resin used in the present invention is suitable.

FIG. 1 shows a configuration of a low reflection touch panel using a transparent conductive film having optical isotropy. The low-reflection touch panel is opposed to the first transparent conductive film 5 and the first transparent conductive film 5 formed on the first quarter-wave plate 3, the glass plate 4, and the glass plate 4 from the liquid crystal panel side. The second transparent conductive film 8 and the optically isotropic film 9 on which the second transparent conductive film 8 is formed, the second quarter-wave plate 10 and the polarizing plate 11 are provided. The optical isotropic film 9 on which the transparent conductive film 8 is formed is a transparent conductive film having the optical isotropy of the present invention.

Next, another low-reflection touch panel is shown in FIG. The present low reflection touch panel includes a first transparent conductive film 5 and a first transparent conductive film 5 formed on the first quarter-wave plate 3, the glass plate 4, and the glass plate 4 from the liquid crystal panel side. The second transparent conductive film 8 and the second quarter-wave plate 10 on which the second transparent conductive film 8 is formed and the polarizing plate 11 are formed. The formed second quarter-wave plate 10 is a transparent conductive film having the function of the quarter-wave plate of the present invention.

The relationship between the slow axis of the first and second quarter wave plates and the transmission axis of the polarizing plate 11 in FIGS. 1 and 2 is shown in FIG. In addition, the half-wave plate and the quarter-wave plate produced by uniaxial stretching are laminated so that the first and second quarter-wave plates have a phase difference of λ / 4 over the visible light wavelength region. The relationship between each slow axis and the transmission axis of the polarizing plate 11 is shown in FIG. By arranging in this way, the light that has entered from above the polarizing plate 11 and returned by reflection at the plurality of interfaces between the first and second quarter-wave plates is absorbed by the polarizing plate 11. Therefore, it becomes low reflection. Further, by making the linearly polarized light from the liquid crystal display the same as the direction of the linearly polarized light described on the liquid crystal display side of FIG. 3A or FIG. Can be transmitted.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the scope of the present invention is not limited by these examples.

<Evaluation method of polyester resin>
(1) Ratio of diol units having a cyclic acetal skeleton The ratio of diol units having a cyclic acetal skeleton in the polyester resin was calculated by ¹ H-NMR measurement. The measuring apparatus used JNM-AL400 by JEOL Co., Ltd., and measured it at 400 MHz. Deuterated chloroform was used as the solvent. Specifically, it was calculated based on the ratio of the peak of the methyl group (derived from the diol component having a cyclic acetal skeleton) to the peak of the benzene ring (derived from the acid component) in the obtained NMR spectrum.
(2) Glass transition temperature As for the glass transition temperature of the polyester resin, DSC / TA-50WS manufactured by Shimadzu Corporation is used, about 10 mg of the polyester resin is put in an aluminum non-sealed container, and the temperature is increased in a nitrogen gas (30 ml / min) stream. A sample heated and melted to 280 ° C. at a rate of 20 ° C./min was rapidly cooled to obtain a measurement sample. The sample was measured under the same conditions, and the temperature at which the difference between the baselines before and after the transition of the DSC curve changed by 1/2 was taken as the glass transition temperature.
(3) Intrinsic Viscosity In the sample for measuring intrinsic viscosity (abbreviated as IV), 0.5 g of polyester resin is dissolved by heating in 120 g of a mixed solvent of phenol and 1,1,2,2-tetrachloroethane (mass ratio = 6: 4). The solution was cooled to 25 ° C. after filtration. The measurement was performed at a temperature of 25 ° C. using a capillary viscometer automatic measuring device SS-300-L1 manufactured by Shibayama Scientific Machinery Co., Ltd.

<Method for evaluating film (film layer)>
(4) Water vapor transmission rate The water vapor transmission rate of each sample was measured under temperature and humidity conditions of 40 ° C. and 90% RH according to the method described in JIS-K-7129 using “L80-4005L” manufactured by LYSSYAG ZLLIKON.
(5) Thickness Measured using a digital micrometer M-30 manufactured by Sony Magnescale Co., Ltd.
(6) Retardation Incidence angle dependency of retardation was measured using a spectroscopic ellipsometer manufactured by JASCO Corporation, trade name: M-220. The measurement wavelength was 550 nm.
(7) Measured according to total light transmittance, haze JIS-K-7105, ASTM D1003. The film was conditioned for 48 hours and then measured in an atmosphere of 23 ° C. and 50% relative humidity. The measuring apparatus used is a fog value measuring apparatus (model: COH-300A) manufactured by Nippon Denshoku Industries Co., Ltd.
(8) Calculation of Nz coefficient and thickness direction retardation Rth
For the Nz coefficient and thickness direction retardation Rth (= [(nx + ny) / 2-nz] × d, where d is the film thickness), the incidence of the retardation around the slow axis in the film plane is measured by a spectroscopic ellipsometer. The angle dependency was measured, and the length of the main axis of the refractive index ellipsoid of the stretched film, that is, the main refractive index nx, ny, and nz, was calculated using the thickness of the stretched film and the resin average refractive index. (April) Fractions were calculated by fitting the characteristic curve and the measured value based on the analytical solution of the incident angle dependence of the retardation in the refractive index ellipsoid model in the optical film described in “GRP wide viewing angle LCD technology”. Using the calculated main refractive indexes nx, ny, and nz and the film thickness d, the Nz coefficient and the thickness direction retardation Rth were determined by the above formula. FIG. 4 shows the measured value (dotted line) of the dependence of the retardation incident angle around the slow axis of the polyester original film on the spectroscopic ellipsometer and the theoretical curve (solid line) based on the above model.
(9) Dimensional change rate Measured according to JIS-K7133. Write a square of 100 x 100 mm on each of the three original films cut into about 120 x 120 mm, put them in a hot air dryer at a predetermined temperature for 30 minutes, and set the dimensional change rate in the extrusion direction and in the direction perpendicular to the extrusion direction. The average value of the three test pieces was calculated as the following formula, and the dimensional change rate in each direction. In the table, the extrusion direction is referred to as MD direction, and the direction perpendicular to the extrusion direction is referred to as TD direction.
Dimensional change rate (%) = {(La−Lb) / La} × 100
La: Distance between lines before putting in hot air dryer (100 mm)
Lb: Spacing between lines after putting in hot air dryer

<Evaluation method of transparent conductive film>
(10) Film thickness The film thickness of the transparent conductive film formed on one side of the polyester film was measured using a spectroscopic ellipsometer manufactured by JASCO Corporation, a product name: M-220.
(11) Specific resistance value The specific resistance value was measured by a four-terminal four-probe method using a surface resistance meter LORESTA (MCP-T600) manufactured by Mitsubishi Chemical Corporation.
(12) Transmittance Using a green laser Compass115M-5 manufactured by Coherent Co., Ltd., a laser beam having a wavelength of 532 nm is incident on the transparent conductive film perpendicularly, the intensity of the transmitted light is measured, and the ratio to the incident intensity is calculated. The transmittance was 532 nm.

<Evaluation method of low reflection touch panel>
(12) Reflectance (wavelength 532 nm)
Using a Coherent green laser Compass115M-5, a laser beam with a wavelength of 532 nm is incident vertically on a low-reflection touch panel, the intensity of the reflected light is measured, the ratio to the incident intensity is taken, and the reflectance at a wavelength of 532 nm is calculated. did.
(13) Reflectance (wavelength 488 nm)
Using a Coherent blue laser Sapphire 488-10, a laser beam with a wavelength of 488 nm is vertically incident on a low-reflection touch panel, the intensity of the reflected light is measured, the ratio to the incident intensity is taken, and the reflectance at a wavelength of 488 nm It was.

Production Examples 1-8
[Production of polyester resin]
The raw material monomers listed in Tables 1 and 2 are charged into a 0.15 cubic meter polyester production apparatus equipped with a packed tower rectification tower, a partial condenser, a full condenser, a cold trap, a stirrer, a heating device, and a nitrogen introduction pipe. In the presence of 0.03 mol% of manganese acetate tetrahydrate with respect to the dicarboxylic acid component, the temperature was raised to 215 ° C. in a nitrogen atmosphere to conduct a transesterification reaction. After the reaction conversion rate of the dicarboxylic acid component is set to 90% or more, 0.02 mol% of antimony (III) oxide and 0.06 mol% of trimethyl phosphate are added to the dicarboxylic acid component, and the temperature and pressure are gradually increased. And finally polycondensation was performed at 270 ° C. and 0.1 kPa or less. The reaction was terminated when an appropriate melt viscosity was reached, and a polyester resin was produced. The evaluation results are shown in Tables 1 and 2.
In addition, the meaning of the abbreviation in a table | surface is as follows.
DMT: dimethyl terephthalate NDCM: 2,6-dimethyl naphthalate DMI: dimethyl isophthalate EG: ethylene glycol SPG: 3,9-bis (1,1-dimethyl-2-hydroxyethyl) -2,4,8,10- Tetraoxaspiro [5.5] undecane

[Manufacture of polyester film]
Using a single-screw extruder with a screw diameter of 50 mmφ with a polyester vent of Production Examples 1 to 8 and a vacuum vent and a 550 mm wide coat hanger die, the cylinder temperature is 220 to 240 ° C., the die temperature is 240 ° C., and the discharge speed is 30 kg / h. Melt extrusion was performed. The extruded molten resin was cooled with a first roll set at Tg-10 ° C. and a second roll set at 60 ° C., and was drawn at 12 m / min to produce a transparent substrate having a thickness of 100 μm and a width length of 480 mm. The evaluation results are shown in Tables 1 and 2 and FIG. FIG. 4 shows the result of the raw film of Production Example 1, but the results were the same for the other Production Examples 2 to 8. Hereinafter, as an example, examples of touch panels using the resin film of Production Example 1 will be described.

Production Example 9
[Manufacture of 1/4 wavelength plate (stretched film)]
The polyester raw film produced in Production Example 1 was uniaxially stretched with a stretching machine. The draw ratio was fixed at 1.5 times and the draw speed was fixed at 30 mm / min. The draw temperature was higher than the glass transition temperature of the polyester resin of Production Example 1, and the increment was + 28.0 ° C. / 4 wavelength plate was manufactured. Table 3 shows each stretching condition, stretched film thickness d, Nz coefficient, and normal incidence retardation Re. The Nz coefficient and normal incidence retardation Re were calculated in the same manner as the polyester raw film.

Production Example 10
[Production of half-wave plate (stretched film)]
A half-wave plate was produced in the same manner as in Example 1 except that the stretching temperature was set to + 22.5 ° C. higher than the glass transition temperature of the polyester resin of Production Example 1. The evaluation results are shown in Table 3.

Production Example 11
[Manufacture of laminated film]
In order to laminate the quarter-wave plate produced in Production Example 9 and the half-wave plate produced in Production Example 10, via an acrylic adhesive [Sumitomo 3M Co., Ltd., DP-8005 Clear], respectively. The slow axes were crossed 60 ° and laminated using a roller.

Example 1
[Deposition of transparent conductive film 1]
Using a sputtering apparatus, a transparent conductive film was formed on one side of the polyester raw film produced in Production Example 1 using IZO as the target material. Table 4 shows the evaluation results of the formed transparent conductive film.

Example 2
[Deposition of transparent conductive film 2]
Using a sputtering apparatus, a transparent conductive film was formed on one side of the quarter-wave plate produced in Production Example 9 using IZO as the target material. Table 5 shows the evaluation results of the formed transparent conductive film.

Example 3
[Transparent conductive film deposition 3]
Using a sputtering apparatus, a transparent conductive film was formed on the quarter-wave plate side surface of the laminated film produced in Production Example 11 using IZO as the target material. Table 6 shows the evaluation results of the formed transparent conductive film.
As described above, the target material using IZO has been described. However, the target material is not limited to this, and well-known ITO can also be used.

Example 4
[Manufacture of low reflection touch panel 1]
The transparent conductive film obtained in Example 1 was used as the portions of the optically isotropic film 9 and the second transparent conductive film 8 in FIG. 1, and the low reflection touch panel shown in FIG. 1 was configured. As the first and second quarter-wave plates, the quarter-wave plates produced in Production Example 9 were used. The relationship between the transmission axis of the polarizing plate and the slow axis of each wave plate is as shown in FIG. When the reflectance at the time of perpendicular incidence with a wavelength of 532 nm of the produced low reflection touch panel was measured, it was 7.5% or less and was satisfactory.

Example 5
[Manufacture of low reflection touch panel 2]
The transparent conductive film obtained in Example 3 was used as the second quarter-wave plate 10 and the second transparent conductive film 8 in FIG. 2 to constitute the low-reflection touch panel shown in FIG. As the first quarter-wave plate, the laminated film produced in Production Example 11 was used. The relationship between the transmission axis of the polarizing plate and the slow axis of each wave plate is as shown in FIG. When the reflectance at the time of perpendicular incidence with the wavelength of 532 nm and the wavelength of 488 nm of the produced low-reflection touch panel was measured, both were good, being 7.3% or less.

Configuration example of low reflection touch panel of the present invention Configuration example of low reflection touch panel of the present invention (A) Arrangement relationship between the transmission axis of the polarizing plate and the slow axis of each wave plate constituting the low reflection touch panel of the present invention (b) The transmission axis of the polarizing plate and each wave plate of the low reflection touch panel of the present invention Slow axis arrangement Spectral ellipsometer measured value (dotted line) and theoretical curve based on refractive index ellipsoid model (solid line) Retardation control by uniaxial stretching of polyester film used in the present invention

Claims (6)

  A surface at a wavelength of 550 nm by stretching a polyester film formed by melt extrusion of a polyester resin containing a dicarboxylic acid unit and a diol unit, wherein 1 to 80 mol% of the diol unit is a diol unit having a cyclic acetal skeleton. At least one surface of a laminated film in which the slow axes of the first polyester stretched film whose inner letter length is controlled in the range of 100 to 175 nm and the second polyester stretched film controlled in the range of 200 to 350 nm are crossed and laminated A transparent conductive film having a transparent conductive film formed thereon. The diol unit having a cyclic acetal skeleton has the general formula (1):
(In the formula, R ¹ and R ² may be the same or different and are each independently an aliphatic hydrocarbon group having 1 to 10 carbon atoms, an alicyclic hydrocarbon group having 3 to 10 carbon atoms, And a hydrocarbon group selected from the group consisting of aromatic hydrocarbon groups having 6 to 10 carbon atoms.)
Or general formula (2):
(In the formula, R ¹ is the same as above, and R ³ is an aliphatic hydrocarbon group having 1 to 10 carbon atoms, an alicyclic hydrocarbon group having 3 to 10 carbon atoms, and 6 to 10 carbon atoms. Represents a hydrocarbon group selected from the group consisting of aromatic hydrocarbon groups of
The transparent conductive film according to claim 1, characterized in that from in the diol represented. The diol unit having a cyclic acetal skeleton is 3,9-bis (1,1-dimethyl-2-hydroxyethyl) -2,4,8,10-tetraoxaspiro [5.5] undecane or 5-methylol- The transparent conductive film according to claim 2 , wherein the transparent conductive film is derived from 5-ethyl-2- (1,1-dimethyl-2-hydroxyethyl) -1,3-dioxane. The diol unit other than the diol unit having a cyclic acetal skeleton is derived from one or more diols selected from ethylene glycol, diethylene glycol, trimethylene glycol, 1,4-butanediol and 1,4-cyclohexanedimethanol. The transparent conductive film in any one of 1-3 . The dicarboxylic acid units, terephthalic acid, a transparent conductive film according to any one of claims 1 to 4, derived from one or more dicarboxylic acid selected from isophthalic acid, and 2,6-naphthalene dicarboxylic acid. A second quarter-wave plate on which at least a first quarter-wave plate, a first transparent conductive film, and a second transparent conductive film facing the first transparent conductive film via a spacer are formed. A transparent conductive film according to claim 1, wherein the second quarter-wave plate is a circularly polarizing type low-reflection touch panel in which a polarizing plate and a polarizing plate are laminated in this order, wherein the second transparent conductive film is formed. A low-reflection touch panel.