JP2014094467A - Polyester film for transparent conductive film substrate and transparent conductive film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyester film for a transparent conductive film substrate, which prevents problems such as patterning failure even when the film is used for a transparent conductive laminate designed to have a narrower pattern width upon patterning an ITO film by a photoresist process or the like, and which can be suitably used as a transparent conductive film substrate.SOLUTION: A laminate polyester film having a thickness of 10 μm or more and 50 μm or less is provided, in which at least one surface side of the film has a maximum surface roughness (Rt) of 10 nm or more and 300 nm or less. A transparent conductive film is provided, including a patterned transparent conductive film laminated on a surface of the polyester film. The width in a thinnest part in the pattern is 15 μm or less.

Description

  The present invention relates to a polyester film used as a base material for a patterned transparent conductive layer used as a constituent base material for a touch panel, and enables high-precision etching when etching a transparent conductive layer laminated thereon. It is related with the polyester film for transparent conductive film base materials in which a defect does not generate | occur | produce in a transparent conductive layer even after the crystallization process of this transparent conductive layer.

  Conventionally, in touch panel applications, various methods such as a resistive film method and a capacitance method are employed depending on the position detection method. Among them, there is a tendency to increase the spread of a capacitance method characterized by multipoint detection, high light transmittance, high resolution, and high response speed. There are two types of capacitive touch panels: surface type and projection type. The surface type consists of three layers: a cover, a transparent conductive layer, and a glass substrate. The projection type consists of a glass or plastic film, a transparent electrode layer, and a substrate layer equipped with an IC that performs arithmetic processing. The

  In the manufacturing process of the transparent conductive laminate, it is generally heat-processed after undergoing a patterning process. First, in order to form a transparent conductive film, an ITO film is formed by a sputtering method. Thereafter, the ITO film is patterned by a photoresist method or the like, and heat-treated at a temperature of about 150 ° C. to crystallize the ITO film, thereby obtaining a patterned transparent conductive laminate.

  The patterned portions of the transparent conductive laminate appear streaky due to the difference in optical properties between the ITO film and the polyester base layer, which is the underlying layer, when the final touch panel member is finished. Sometimes. The pattern width of the ITO film has become narrower in recent years because the streaks of the pattern area are particularly noticeable when reflected over reflected light such as a fluorescent lamp, and the appearance quality of the final touch panel display product is reduced. Tend to be designed.

  In general, particles are blended in the polyester film substrate mainly for the purpose of imparting slipperiness and preventing scratches in each step. If more particles are added and the surface roughness of the polyester film substrate is designed to be high, the handleability during processing of the substrate will increase, but if there is an aggregate of particles in the ITO pattern part, the photoresist This may have an adverse effect on the uniform patterning of the ITO layer by the method. In particular, in the transparent conductive laminate of the type designed to have a narrower pattern width in recent years, there has been a tendency for defects in patterning to occur frequently. On the other hand, if the polyester base material is not blended with particles, scratches that occur when the film passes through the roll path in each step occur on the entire surface of the film, and it is extremely difficult to process a transparent conductive laminate having a good appearance. It is.

JP 2007-200823 A

  The present invention has been made in view of the above circumstances, and the problem to be solved is that it is used for a transparent conductive laminate of a type designed to have a narrower pattern width when patterning an ITO film by a photoresist method or the like. The present invention relates to a polyester film for a transparent conductive film substrate in which defects such as poor patterning do not occur, and to provide a polyester film that can be suitably used as a transparent conductive film substrate.

  As a result of intensive studies in view of the above circumstances, the present inventors have found that the above-described problems can be easily solved by a polyester film having a specific configuration, and have completed the present invention.

  That is, the gist of the present invention is a laminated polyester film having a thickness of 10 μm or more and 50 μm or less, and at least one surface roughness maximum roughness (Rt) of 10 nm or more and 300 nm or less. A transparent conductive film in which a patterned conductive film and a transparent conductive film patterned on the surface of the polyester film are laminated, and the width of the finest pattern of the pattern is 15 μm or less. Exist.

  According to the polyester film for a transparent conductive film substrate of the present invention, when patterning an ITO film by a photoresist method or the like, even when used for a transparent conductive laminate of a type designed to have a narrower pattern width, The present invention relates to a polyester film for a transparent conductive film substrate that does not cause defects such as poor formation, and can provide a polyester film that can be suitably used as a transparent conductive film substrate, and its industrial value is high.

  The optical laminated polyester film of the present invention is preferably a multilayer film having at least 3 layers. The laminated polyester film for optics referred to in the present invention is a polyester film extruded by a so-called extrusion method that is melt-extruded from an extrusion die, and is oriented in the biaxial direction of the vertical direction and the horizontal direction as necessary. Film.

  In the present invention, the polyester is obtained by polycondensation of an aromatic dicarboxylic acid and an aliphatic glycol. Examples of the aromatic dicarboxylic acid include terephthalic acid and 2,6-naphthalenedicarboxylic acid, and examples of the aliphatic glycol include ethylene glycol, diethylene glycol, and 1,4-cyclohexanedimethanol. Typical polyesters include polyethylene terephthalate (PET), polyethylene-2,6-naphthalenedicarboxylate (PEN) and the like.

  The polyester used in the present invention may be a homopolyester or a copolyester. In the case of a copolyester, it is a copolymer containing 30 mol% or less of the third component. Examples of the dicarboxylic acid component of the copolyester include isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, sebacic acid, and oxycarboxylic acids (for example, P-oxybenzoic acid). Or 2 or more types are mentioned, As a glycol component, 1 type, or 2 or more types, such as ethylene glycol, diethylene glycol, propylene glycol, butanediol, 1, 4- cyclohexane dimethanone neopentyl glycol, is mentioned.

  Both outermost layers of the film of the invention are composed of 60% or more, more preferably 70% or more, more preferably 80% or more of polyester having an oligomer (cyclic trimer) content of 0.5% by weight or less. It is preferable. When a polyester having an oligomer content of more than 0.5% by weight is used, or when the composition ratio of the polyester is less than 60%, the laminated polyester has a long heat treatment under 150 ° C. condition and high tension. When used in processing steps under severe conditions such as sputtering processes under such conditions and durability tests in high-temperature and high-humidity atmospheres, the film haze increases greatly, and after processing as a product, optical characteristics There is a high possibility that it is not suitable for optical members in terms of visibility.

  The film of the present invention preferably has a thickness of both outermost layers of 4 μm or more, more preferably 5 μm or more, and further preferably 6 μm or more. When the thicknesses of both outermost layers are less than 4 μm, the oligomer precipitation sealing effect of the outermost layer having a low oligomer (cyclic trimer) content is diminished.

  The total film thickness of the film of the present invention is in the range of 10 μm to 50 μm. When the total film thickness is less than 10μm, when forming the ITO film by sputtering method to form a transparent conductive film, the film strength is lost to the processing tension, wrinkles occur and the transparent conductive film is formed properly There is a fear that it cannot be done. In addition, when the thickness exceeds 50 μm, the film becomes too strong and the touch effect of the touch panel is reduced due to the cushioning effect of the adhesive layered on the film of the present invention when finished to the final touch panel product. A phenomenon such as a decrease occurs.

It is essential that the maximum roughness (Rt) on at least one side of the film of the present invention is 10 nm or more and 300 nm or less, and more preferably the maximum roughness (Rt) is 10 nm or more and 120 nm or less. When the maximum roughness (Rt) is less than 10 nm, the surface is too smooth, and there is a high possibility that scratches will occur when the polyester film is formed. On the other hand, when it exceeds 300 nm, on the transparent conductive film after patterning Therefore, there is a high possibility that the disconnection of the wiring will occur in the crystallization process of the transparent conductive layer, particularly in the thinly patterned portion.

In the polyester layer of the film of the present invention, particles may be blended mainly for the purpose of imparting slipperiness and preventing scratches in each step. The kind of the particle to be blended is not particularly limited as long as it is a particle capable of imparting slipperiness. Specific examples thereof include silica, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, and phosphoric acid. Examples of the particles include magnesium, kaolin, aluminum oxide, and titanium oxide. Further, the heat-resistant organic particles described in JP-B-59-5216, JP-A-59-217755 and the like may be used. Examples of other heat-resistant organic particles include thermosetting urea resins, thermosetting phenol resins, thermosetting epoxy resins, benzoguanamine resins, and the like.
Furthermore, precipitated particles obtained by precipitating and finely dispersing a part of a metal compound such as a catalyst during the polyester production process can also be used.

  On the other hand, the shape of the particles to be used is not particularly limited, and any of a spherical shape, a block shape, a rod shape, a flat shape, and the like may be used. Moreover, there is no restriction | limiting in particular also about the hardness, specific gravity, a color, etc. These series of particles may be used in combination of two or more as required.

  The average particle size of the particles blended in the polyester film is not particularly limited, but is usually 0.001 μm to 1 μm, preferably 0.001 μm to 0.8 μm, and more preferably 0.001 μm to 0.5 μm. Range. When particles having an average particle size of less than 0.001 μm are used, sufficient slipperiness cannot be imparted, so that the winding characteristics in the film production process tend to be inferior. Further, when the average particle diameter exceeds 1 μm, the degree of roughening of the film surface becomes too high, and there is a high possibility that the maximum roughness claimed in this patent cannot be satisfied.

  Furthermore, the content of particles in the polyester layer is usually in the range of 0.0005 to 0.5% by weight, preferably 0.001 to 0.5% by weight. When the particle content is less than 0.0005% by weight, the slipperiness of the film may be insufficient, resulting in poor appearance such as scratches during film processing. On the other hand, when adding over 0.5 weight%, the transparency of a film may be inadequate.

  In the present invention, the method of blending the particles with the polyester is not particularly limited, and a known method can be adopted. For example, it can be added at any stage of producing the polyester, but it is preferably added as a slurry dispersed in ethylene glycol or the like at the stage of esterification or before the start of the polycondensation reaction after completion of the transesterification reaction, The polycondensation reaction may proceed. Also, a method of blending a slurry of particles dispersed in ethylene glycol or water with a vented kneading extruder and a polyester raw material, or a blending of dried particles and a polyester raw material using a kneading extruder. It is done by methods.

  The polyester film of the present invention may be formed with a coating layer on one or both sides of the film in order to impart functions such as adhesiveness, antistatic property, slipperiness and releasability to the film during and / or after the stretching process. Surface treatment such as corona treatment may be performed.

  In the laminated polyester film for optics of the present invention, a coating layer may be provided for the purpose of improving the adhesion with the layer processed on it, improving the slipperiness during processing, and the like. Regarding the coating layer, it may be provided by in-line coating which treats the film surface during the process of forming a polyester film, or offline coating which is applied outside the system on a once produced film may be adopted. Since the coating can be performed simultaneously with the film formation, the production can be handled at a low cost, and therefore inline coating is preferably used.

  The in-line coating is not limited to the following, but for example, in the sequential biaxial stretching, the coating treatment can be performed particularly before the lateral stretching after the longitudinal stretching is finished. When the coating layer is provided on the polyester film by in-line coating, it is possible to apply at the same time as the film formation, and the coating layer can be processed at a high temperature in the heat treatment process of the polyester film after stretching. Performances such as adhesion to various surface functional layers that can be formed on the layer and heat-and-moisture resistance can be improved. Moreover, when coating before extending | stretching, the thickness of an application layer can also be changed with a draw ratio, and compared with off-line coating, uniform coating can be performed with a thin film. That is, a film suitable as a polyester film can be produced by in-line coating, particularly coating before stretching.

  Moreover, the coating layer of the film of the present invention comprises a surfactant, an antifoaming agent, a coating property improving agent, a thickener, an organic lubricant, organic particles, inorganic particles, an antioxidant, an ultraviolet absorber, a foaming agent, It may contain additives such as dyes and pigments. These additives may be used alone or in combination of two or more as necessary.

As long as water is the main medium, the coating agent may contain a small amount of an organic solvent for the purpose of improving dispersion in water or improving the film-forming performance. It is necessary to use the organic solvent as long as it is soluble in water. Examples of the organic solvent include aliphatic or alicyclic alcohols such as n-butyl alcohol, n-propyl alcohol, isopropyl alcohol, ethyl alcohol, and methyl alcohol, glycols such as propylene glycol, ethylene glycol, and diethylene glycol, n-butyl cellosolve, Glycol derivatives such as ethyl cellosolve, methyl cellosolve, propylene glycol monomethyl ether, ethers such as dioxane and tetrahydrofuran, esters such as ethyl acetate and amyl acetate, ketones such as methyl ethyl ketone and acetone, amides such as N-methylpyrrolidone Can be mentioned.
These organic solvents may be used in combination of two or more as required.

  Moreover, you may use together heat treatment and active energy ray irradiation, such as ultraviolet irradiation, as needed irrespective of offline coating or in-line coating as needed. The polyester film constituting the laminated polyester film in the present invention may be subjected to surface treatment such as corona treatment or plasma treatment in advance. Such a coat may be either single-sided or double-sided. The coating material may be either water-based and / or solvent-based for off-line coating, but is preferably water-based or water-dispersed for in-line coating.

  The coating liquid used in the present invention is preferably an aqueous solution or an aqueous dispersion in terms of handling and working environment, but contains water as the main medium and contains an organic solvent as long as it does not exceed the gist of the present invention. You may do it.

  Although there is no restriction | limiting in particular in the solid content density | concentration of a coating liquid, Usually, 0.3 to 65 weight%, Preferably it is 0.5 to 30 weight%, More preferably, it is 1 to 20 weight%. When the concentration is too high or too low than these ranges, it may be difficult to provide a coating layer having a thickness necessary for fully expressing the function.

  The thickness of a coating layer is dry thickness, and is 0.003-1.5 micrometers normally, Preferably it is 0.01-0.5 micrometer, More preferably, it is 0.01-0.3 micrometer. If the thickness of the coating layer is less than 0.003 μm, sufficient performance may not be obtained, and if it exceeds 1.5 μm, blocking between films tends to occur.

  As a coating method of the coating agent, for example, a reverse roll coater, a gravure coater, a rod coater, an air doctor coater, or a coating apparatus other than these as shown in Yuji Harasaki, Tsuji Shoten, published in 1979, “Coating Method” Can be used.

  In the present invention, it is preferable to contain inorganic particles or organic particles in the coating layer in order to further improve the slipperiness, adhesion and the like. The amount of the particles in the coating agent is usually 0.5 to 10% by weight, preferably 1 to 5% by weight. When the blending amount is less than 0.5% by weight, the blocking resistance may be insufficient. When the blending amount exceeds 10% by weight, the transparency of the film is hindered and the sharpness of the image tends to be lowered.

  Examples of the inorganic particles include silicon dioxide, alumina, zirconium oxide, kaolin, talc, calcium carbonate, titanium oxide, barium oxide, carbon black, molybdenum sulfide, and antimony oxide. Among these, silicon dioxide is easy to use because it is inexpensive and has various particle sizes.

  Examples of the organic particles include polystyrene or polyacrylate polymethacrylate in which a crosslinked structure is achieved by a compound (for example, divinylbenzene) containing two or more carbon-carbon double bonds in one molecule.

  The above inorganic particles and organic particles may be surface-treated. Examples of the surface treatment agent include a surfactant, a polymer as a dispersant, a silane coupling agent, a titanium coupling agent, and the like. The content of the particles in the coating layer is preferably 10% by weight or less, more preferably 5% by weight or less as an appropriate addition amount that does not impair the transparency.

  The coating layer may contain an antifoaming agent, a coating property improving agent, a thickener, an antioxidant, an ultraviolet absorber, a foaming agent, a dye, a pigment, and the like.

  For the laminated polyester film in the present invention, for example, for a touch panel or the like, high transparency may be required even after being exposed to a high temperature atmosphere for a long time. From this viewpoint, in order to correspond as a member for a touch panel, the film haze change rate (ΔH) before and after heat treatment (150 ° C., 90 minutes) is preferably 0.5% or less, more preferably 0.3%. Hereinafter, 0.1% or less is most preferable. When ΔH exceeds 0.5%, the visibility decreases as the film haze increases, and may be inappropriate for applications that require high visibility, such as for touch panels.

  The polyester film of the present invention can be mixed with other thermoplastic resins such as polyethylene naphthalate and polytrimethylene terephthalate as long as the effects of the present invention are not impaired. Moreover, you may mix | blend coloring agents, such as a ultraviolet absorber, antioxidant, surfactant, a fluorescent whitening agent, a lubricant agent, a light-shielding agent, a matting agent, and a dye, a pigment. In addition, for the purpose of improving the slipperiness and abrasion resistance of the film, inert inorganic or organic fine particles can be blended with the polyester as necessary.

The amount (OL) of oligomer (cyclic trimer) extracted from the film surface before and after heat treatment (150 ° C., 90 minutes) of the laminated polyester film in the present invention is 0.5 mg / m ² or less. Is more preferable, and 0.4 mg / m ² or less is more preferable. When OL exceeds 0.5 mg / m ² , in post-processing, for example, 150 ° C., 90 minutes, etc., in a high temperature atmosphere, the oligomer deposition amount increases and the transparency of the film decreases. There is a case.

It is preferable to laminate a transparent conductive film on the surface having the maximum roughness (Rt) of 10 nm or more and 300 nm or less of the laminated polyester film in the present invention. As a constituent material of the transparent conductive film, a metal oxide is preferably used from the viewpoints of transparency, durability, and weather resistance. In particular, indium tin oxide (ITO), antimony-containing indium tin oxide (ATO), Tin oxide, zinc oxide (ZnO), indium zinc oxide (In ₂ O ₃ —ZnO) and the like are particularly preferably used.

  About the formation method of a transparent conductive film, it does not specifically limit, A conventionally well-known method is employable. Specific examples include vacuum deposition, sputtering, and ion plating.

  An anchor coating can be applied between the transparent conductive film and the polyester film substrate for the purpose of improving the adhesion and improving the appearance, if necessary. The constituent material of the anchor coat layer is not particularly limited. For example, silicon oxide, aluminum oxide, magnesium fluoride, etc. are preferably used among inorganic substances. Among organic substances, acrylic resin, urethane resin, melamine resin, polyester resin, melamine resin, polycarbonate resin, polyolefin resin, polyvinyl resin, polyvinyl alcohol resin, organosilane polymer, and the like are preferably used.

  The formed transparent conductive film is patterned by etching. The shape of the pattern depends on the design of the touch panel that is the final product, but the finest details of the patterned portion are 15 μm or less, preferably 1 μm or more and 13 μm or less, more preferably 5 μm or more and 10 μm or less. If the finest part of the patterned part is less than 1 μm, the conductive part is too thin and may be broken by a slight impact. On the other hand, if the finest part of the patterned part exceeds 15 μm, the streaks of the pattern part are remarkable. The appearance quality when finished to the final touch panel display product is reduced.

  The transparent conductive film patterned by the etching process is heated and crystallized. It is preferable that the temperature of heat processing is the range of 100 to 180 degreeC normally. When the temperature is lower than 100 ° C., there is a high possibility that the crystallization of the transparent conductive film does not proceed sufficiently. On the other hand, when the temperature exceeds 180 ° C., the oligomer component precipitates from the polyester substrate and the transparency of the entire transparent conductive film There is a possibility that side effects such as falling will occur.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example, unless the summary is exceeded. In the examples and comparative examples, “parts” means “parts by weight”. The measuring method used in the present invention is as follows.

(1) Measurement of intrinsic viscosity of polyester 1 g of polyester from which other polymer components and pigments incompatible with polyester have been removed are precisely weighed, and 100 ml of a mixed solvent of phenol / tetrachloroethane = 50/50 (weight ratio) is added. It was dissolved and measured at 30 ° C.

(2) Average particle diameter (d50)
The particle size was measured by a sedimentation method based on Stokes' resistance law using a centrifugal sedimentation type particle size distribution analyzer SA-CP3 manufactured by Shimadzu Corporation.

(3) Measuring method of amount of oligomer contained in polyester raw material About 200 mg of the polyester raw material is weighed and dissolved in 2 ml of a mixed solvent of chloroform / HFIP (hexafluoro-2-isopropanol) ratio 3: 2. After dissolution, add 20 ml of chloroform, and then add 10 ml of methanol little by little. The precipitate is removed by filtration, and the precipitate is further washed with a mixed solvent having a chloroform / methanol ratio of 2: 1. The filtrate / washing solution is collected, concentrated by an evaporator, and then dried. After the dried product was dissolved in 25 ml of DMF (dimethylformamide), this solution was supplied to liquid chromatography (manufactured by Shimadzu Corporation: LC-7A) to determine the amount of oligomer in DMF, and this value was obtained as a chloroform / HFIP mixed solvent. Divide by the amount of the polyester raw material dissolved in the amount to make the amount of oligomers contained (% by weight). The amount of oligomer in DMF was determined from the peak area ratio between the standard sample peak area and the measured sample peak area (absolute calibration curve method).

  The standard sample was prepared by accurately weighing an oligomer (cyclic trimer) collected in advance and dissolving it in accurately measured DMF. The concentration of the standard sample is preferably in the range of 0.001 to 0.01 mg / ml.

The conditions for the liquid chromatograph were as follows.
Mobile phase A: Acetonitrile Mobile phase B: 2% acetic acid aqueous solution Column: “MCI GEL ODS 1HU” manufactured by Mitsubishi Chemical Corporation
Column temperature: 40 ° C
Flow rate: 1 ml / min Detection wavelength: 254 nm

(4) Thickness of Laminated Polyester Layer After fixing a small piece of film with an epoxy resin, it was cut with a microtome, and the cross section of the film was observed with a transmission electron micrograph. Two of the cross-sections are observed in parallel with the film surface, and the interface is observed by light and dark. The distance between the two interfaces and the film surface was measured from 10 photographs, and the average value was defined as the laminated thickness.

(5) Method for measuring the amount of oligomer (cyclic trimer) extracted from the surface of the laminated polyester film In advance, the untreated laminated polyester film is heated in air at 150 ° C. for 90 minutes. Thereafter, the heat-treated film is brought into close contact with the inner surface of a box having an upper portion of 10 cm in length and width of 3 cm and a height of 3 cm to form a box shape. When the coating layer is provided, the coating layer surface is set to the inside. Next, 4 ml of DMF is placed in the box prepared by the above method and left for 3 minutes, and then DMF is recovered. The recovered DMF was supplied to liquid chromatography (manufactured by Shimadzu Corporation: LC-7A) to determine the amount of oligomer in DMF, and this value was divided by the film area in contact with DMF to obtain the amount of film surface oligomer (mg / M ² ).
In addition, the amount of oligomers in DMF was calculated according to the absolute calibration curve method described in (3) Method for measuring amount of oligomer contained in polyester raw material.

(6) Wiring disconnection evaluation after patterning of transparent conductive film In the polyester film, on the surface opposite to the coating layer, indium oxide 95 in an atmosphere of 0.4 Pa composed of argon gas 95% and oxygen gas 5%. An ITO film (transparent conductive thin film) having a thickness of 25 nm was formed by a reactive sputtering method using a sintered body material of 5% by weight and 5% by weight of tin oxide. After applying a patterned photoresist on the ITO film (most detail: 8 μm, 12 μm, 20 μm) and drying and curing, the obtained ITO film was made into 4% hydrogen chloride aqueous solution (manufactured by Wako Pure Chemical Industries). It was immersed in and etched. The obtained patterned ITO film was crystallized by heat treatment at 150 ° C. for 1 hour.
100 locations of the ITO film after patterning obtained are inspected with an optical microscope (Keyence Corp., digital microscope model number: VHX-200) at a magnification of 40 times, and the presence or absence of breakage of ITO is inspected. The wire disconnection after the transparent conductive film patterning was evaluated according to the following criteria.
○: No disconnection of the ITO wiring is confirmed Δ: No disconnection of the ITO wiring is confirmed, but a phenomenon such as cracking of the wiring is confirmed ×: A disconnection of the ITO wiring is confirmed at one or more places

(7) Film processing suitability During the sputtering process by the above method, the flatness of the film of the processed part was visually evaluated.
○: The processed portion of the film is well processed without waviness and wrinkles in the entire width direction. ×: Waviness and wrinkles are generated in the processed portion of the film, and it cannot be processed uniformly in the width direction.

(8) Cushion effect of adhesive (practical property substitution evaluation)
The new peel-side non-carrier film “KF4 # 50” was peeled off from the light release side separator and bonded to the coated layer surface of the laminated polyester film. Next, the heavy-separation side separator was peeled off, and a laminated polyester film / adhesive layer / glass structure was prepared by bonding to a sheet glass ("float sheet glass (5 mm thickness)") manufactured by Nippon Sheet Glass Co., Ltd. The pen tip of the ballpoint pen was brought into contact from the side, and the cushioning effect of the adhesive was determined according to the following criteria.
<Criteria>
○: While the pen is in contact, the adhesive layer follows the contacted area. When contact is stopped, the follow-up deformation of the adhesive layer is restored (you can feel the cushion effect)
×: Even if the pen is brought into contact, the adhesive layer is not deformed and the cushion effect cannot be felt.

(9) Surface roughness Maximum roughness (Rt)
Parallel to the average line of the portion (hereinafter referred to as the extracted portion) extracted by the reference length (2.5 mm) from the cross-sectional curve obtained by the surface roughness measuring device “SE-3F” manufactured by Kosaka Laboratory Ltd. 2 When the extracted part is sandwiched by a straight line, the maximum peak and the deepest valley in the interval between these two straight lines are sandwiched by two straight lines parallel to the average line, and the value obtained by dividing the interval by the vertical magnification is in units of micrometers (nm) Was taken as the maximum height (Rt) of the extracted portion. The radius of the stylus used at this time was 2.0 μm, the load was 30 mg, and the cutoff value was 0.08 mm.

<Manufacture of polyester>
[Method for producing ester (A)]
Using 100 parts by weight of dimethyl terephthalate and 60 parts by weight of ethylene glycol as starting materials, 0.09 parts by weight of magnesium acetate tetrahydrate as a catalyst is placed in the reactor, the reaction start temperature is set to 150 ° C., and the methanol is distilled off gradually. The reaction temperature was raised to 230 ° C. after 3 hours. After 4 hours, the transesterification reaction was substantially terminated. After adding 0.04 part of ethyl acid phosphate to this reaction mixture, 0.04 part of antimony trioxide was added, and a polycondensation reaction was carried out for 4 hours. That is, the temperature was gradually raised from 230 ° C. to 280 ° C. On the other hand, the pressure was gradually reduced from normal pressure, and finally 0.3 mmHg. After the start of the reaction, the reaction was stopped at a time corresponding to an intrinsic viscosity of 0.63 due to a change in stirring power of the reaction tank, and the polymer was discharged under nitrogen pressure. The obtained polyester (A) had an intrinsic viscosity of 0.65 and an oligomer (cyclic trimer) content of 0.97% by weight.

[Production method of polyester (B)]
Polyester (A) is pre-crystallized at 160 ° C. in advance, and then solid-phase polymerized in a nitrogen atmosphere at a temperature of 220 ° C., limiting viscosity 0.75, oligomer (cyclic trimer) content 0.46% by weight. Polyester (B) was obtained.

[Production method of polyester (C)]
In the method for producing polyester (A), after adding 0.04 part of ethyl acid phosphate, 0.2 part of silica particles dispersed in ethylene glycol having an average particle diameter of 1.6 μm and 0.04 part of antimony trioxide are added. In addition, polyester (C) was obtained using the same method as the production method of polyester (A) except that the polycondensation reaction was stopped at the time corresponding to the intrinsic viscosity of 0.65. The obtained polyester (C) had an intrinsic viscosity of 0.65 and an oligomer (cyclic trimer) content of 0.82% by weight.

[Production method of polyester (D)]
In the polyester (A) production method, after adding 0.04 part of ethyl acid phosphate, the content of aluminum oxide particles dispersed in ethylene glycol having an average particle diameter of 60 nm is 1.5% by weight with respect to the polyester. And a polycondensation reaction was carried out for 4 hours to obtain polyester (D). The obtained polyester (D) had an intrinsic viscosity of 0.61 and an oligomer (cyclic trimer) content of 0.77% by weight.

[Production method of polyester (E)]
In the method for producing polyester (A), the method for producing polyester (D) is the same except that the particle type to be added is divinylbenzene-crosslinked polystyrene particles having an average particle size of 0.4 μm and the content to the polyester is 0.5% by weight. Polyester (E) was obtained by the same method. The obtained polyester (E) had an intrinsic viscosity of 0.61 and an oligomer (cyclic trimer) content of 0.78% by weight.

[Production method of polyester (F)]
In the production method of polyester (A), polyester (D) is used except that the particle type to be added is calcium carbonate particles dispersed in ethylene glycol having an average particle diameter of 0.7 μm, and the content with respect to the polyester is 2.0% by weight. ) To obtain a polyester (F) by the same method. The obtained polyester (F) had an intrinsic viscosity of 0.61 and an oligomer (cyclic trimer) content of 0.82% by weight.

Example 1:
A mixture of the above polyesters (B) and (D) at a ratio of 80% and 20% is used as the raw material for the A layer, and 100% of the polyester (A) is used as the raw material for the B layer. Each was supplied to the machine and melted at 285 ° C., then the A layer was the outermost layer (surface layer), the B layer was the intermediate layer, and on the casting drum cooled to 40 ° C., two types and three layers (ABA), A non-oriented sheet was obtained by coextrusion and cooling and solidification so that the thickness composition ratio was A: B: A = 5: 13: 5. Next, the film was stretched 3.4 times in the machine direction at a film temperature of 85 ° C. using the roll peripheral speed difference, and then this longitudinally stretched film was guided to a tenter and stretched 4.3 times at 120 ° C. in the transverse direction. After heat-treating, the film was rolled up on a roll and coated on one side with the coating solution prepared by the preparation method described below so that the film thickness was 0.1 μm after drying, and a laminated polyester film having a thickness of 23 μm was formed. Obtained. The properties of the obtained film are shown in Table 1 below.

[Preparation of coating solution]
The following compounds A, B, C, D, and E were mixed so as to be 30, 10, 40, 10, and 10 parts by weight, respectively.
-Quaternary ammonium base-containing polymer (A):
2-hydroxy-3-methacryloxypropyltrimethylammonium salt polymer Counter ion: methyl sulfonate Number average molecular weight: 30000
-Polyethylene glycol-containing acrylate polymer (B):
Polyethylene glycol-containing monoacrylate polymer Number average molecular weight: 20000
・ Crosslinking agent (C): Melamine crosslinking agent (DIC: Becamine)
Particle (D): Alumina surface modified colloidal silica (average particle size: 50 nm)
Binder (E): polyvinyl alcohol (saponification degree 88 mol%, polymerization degree 500)

Example 2:
In Example 1, a polyester film was obtained in the same manner as in Example 1 except that polyesters (B) and (D) were mixed as the raw material of the layer A at a ratio of 70% and 30%, respectively. The characteristics of the obtained laminated polyester film are shown in Table 1 below.

Example 3:
In Example 1, polyesters (B), (D), and (E) as raw materials for the A layer were mixed in proportions of 67%, 30%, and 3%, respectively, and the thickness composition ratio was A: B: A = 5. A polyester film was obtained in the same manner as in Example 1 except that the thickness of the obtained laminated polyester film of 28: 5 was 38 μm. The characteristics of the obtained laminated polyester film are shown in Table 1 below.

Example 4:
In Example 1, polyesters (B), (D), and (E) as raw materials for the A layer were mixed in proportions of 64%, 30%, and 6%, respectively, and the thickness composition ratio was A: B: A = 5. A polyester film was obtained in the same manner as in Example 1 in which the thickness of the obtained laminated polyester film of 35: 5 was 45 μm. The characteristics of the obtained laminated polyester film are shown in Table 1 below.

Example 5:
In Example 1, polyesters (A), (D), and (E) were mixed as raw materials for the A layer in proportions of 64%, 30%, and 6%, respectively, and the thickness composition ratio was A: B: A = 5. : A polyester film was obtained in the same manner as in Example 1 except that the thickness of the obtained laminated polyester film of 40: 5 was 50 μm. The characteristics of the obtained laminated polyester film are shown in Table 1 below.

Example 6:
In Example 1, a polyester film was obtained in the same manner as in Example 1 except that the thickness ratio was A: B: A = 5: 2: 5 and the thickness of the resulting laminated polyester was 12 μm. It was. The characteristics of the obtained laminated polyester film are shown in Table 1 below.

Comparative Example 1:
In Example 1, a polyester film was obtained in the same manner as in Example 1 except that polyesters (A) and (C) were mixed in the proportions of 84% and 16%, respectively, as the raw material for the A layer. The characteristics of the obtained laminated polyester film are shown in Table 1 below.

Comparative Example 2:
In Example 1, polyesters (B) and (C) as raw materials for the layer A were mixed at a ratio of 84% and 16%, respectively, and the thickness composition ratio was set to A: B: A = 5: 28: 5. A polyester film was obtained in the same manner as in Example 1 except that the thickness of the laminated polyester was 38 μm. The characteristics of the obtained laminated polyester film are shown in Table 1 below.

Comparative Example 3:
In Example 1, polyesters (B) and (F) as raw materials for the A layer were mixed in proportions of 83% and 17%, respectively, and the thickness composition ratio was set to A: B: A = 5: 28: 5. A polyester film was obtained in the same manner as in Example 1 except that the thickness of the laminated polyester was 38 μm. The characteristics of the obtained laminated polyester film are shown in Table 1 below.

Comparative Example 4:
In Example 1, a polyester film was obtained in the same manner as in Example 1 except that the thickness ratio was A: B: A = 4: 1: 4 and the thickness of the resulting laminated polyester was 9 μm. . The characteristics of the obtained laminated polyester film are shown in Table 1 below.

Comparative Example 5:
In Example 1, a polyester film was obtained in the same manner as in Example 1 except that the thickness ratio was A: B: A = 5: 65: 5 and the thickness of the resulting laminated polyester was 75 μm. It was. The characteristics of the obtained laminated polyester film are shown in Table 1 below.

  The film of the present invention can be suitably used as, for example, a polyester film for a transparent conductive film substrate.

Claims (2)

A polyester film for a transparent conductive film substrate, wherein the polyester film is a laminated polyester film having a thickness of 10 μm or more and 50 μm or less, and at least one surface roughness maximum roughness (Rt) of 10 nm or more and 300 nm or less. A transparent conductive film in which a patterned transparent conductive film is laminated on the surface of the polyester film according to claim 1, wherein the width of the finest pattern is 15 μm or less.