JP6515445B2 - Polyester film roll for surface protection film and conductive film laminate - Google Patents

Description

  The present invention relates to a polyester film for a surface protection film to be used by bonding to a transparent conductive film and a laminate thereof, and more specifically, a polyester film for a surface protection film having excellent handling properties and processability, and It relates to the laminate.

  Conventionally, synthetic resin plates, glass plates, metal plates, for optical members (glass substrates, light diffusion films, liquid crystal displays (polarizers, retardation plates, light guide plates, prism plates, etc.), touch panels, organic EL displays, plasma displays, etc. ) For the purpose of surface protection of various adherends, in order to prevent surface dirt, scratches, dust, etc., such as automobile parts, electric / electronic parts, construction materials, stationery and office supplies, etc. A surface protection film provided with an adhesive layer on one side is used. However, with such a surface protection film attached to an adherend, it is exposed to a high temperature atmosphere during heat treatment in a high temperature atmosphere or during transportation or storage (patent documents 1 and 2) When it is used in the above, deformation due to melting or shrinkage of the substrate film is large, making it difficult to use.

  On the other hand, biaxially oriented polyester films are excellent in transparency, dimensional stability, mechanical properties, heat resistance, electrical properties, gas barrier properties, chemical resistance, etc., and packaging materials, plate making materials, display materials, transfer materials, They are used in construction materials, window paste materials, etc., membrane switches, antireflection films used in flat displays, etc., diffusion sheets, optical films such as prism sheets, transparent touch panels, etc. Since a material called polyester is obtained relatively inexpensively, it is also suitably used as a substrate of a protective film used in the process of various functional films described above (Patent Document 3).

  In recent years, an electronic display having a touch panel function has rapidly penetrated into daily life because of its convenience, but the screen size of the electronic display itself has been increased to further expand the range of use. At the beginning of the market when the electronic display appeared on the market, the mainstream was the size that was placed on the palm, but then the notebook size (A4), 15 to 19 inch size (personal computer screen), TV size, etc. one after another New products equipped with large screens have come to the market. With the increase in screen size, handling property and processability at the time of processing a transparent conductive film, which is an essential member for realizing a touch panel function, have come to be regarded as important.

  A heat treatment is applied in the step of crystallization of the conductive film layer among the production steps for producing the transparent conductive film, and this heat treatment is carried out in a state where the surface protective film is attached via the adhesive layer. To be implemented. Usually, in the base material of the transparent conductive film and the base material of the surface protective film, since the base material of the surface protective film is thicker, the shape change of the laminate at the time of heat treatment is dominated by the characteristics of the surface protective film Become. In the production of the transparent conductive film for electronic display of the conventional size, even if the shape change such as the curl of the above-mentioned laminate occurs, the area is small, so the absolute amount of the change is limited. Although no problem was caused, when the transparent conductive film for an electronic display having a large screen was manufactured, the amount of change in shape of the curl was large due to the large area, and the contact between the member and the equipment in the heating furnace There is a problem that appearance defects such as generation of scratches are scattered.

  Even when producing a transparent conductive film for an electronic display having a large screen, a base material of a surface protection film having thermal characteristics that can cause a crystallization process of the conductive layer with little occurrence of curling and the like without problems is provided. It is required to do.

Unexamined-Japanese-Patent No. 2006-299162 JP, 2008-68564, A Unexamined-Japanese-Patent No. 2012-232488 gazette

  The present invention has been made in view of the above-described circumstances, and the problem to be solved is that when the transparent conductive film is manufactured and used as a surface protective film, the laminate has excellent handling properties and processing. It is an object of the present invention to provide a polyester film for surface protection film having a thermal property that develops a property and a laminate thereof.

  The inventors of the present invention have found that the above-mentioned problems can be solved by controlling the shrinkage characteristics of the polyester film used as a base material of the surface protection film within a certain range as a result of intensive studies on the above-mentioned problems. The present invention has been completed.

That is, the gist of the present invention is a polyester film having a thickness of 100 μm or more and a surface roughness (Ra) of 23 nm or less , and after heating at 150 ° C. for 30 minutes at every 100 mm in the TD direction of the film. Polyester for surface protection film characterized in that the shrinkage ratio between the film MD direction and the TD direction satisfies the following formula (1) or (2), and the length of the film in the direction orthogonal to the MD direction is 1000 mm or more A film roll and a laminate characterized in that the film is bonded to a conductive film through an adhesive layer.
| Maximum contraction rate in the MD direction-minimum contraction rate in the TD direction | ≦ 0.6% (1)
| Maximum value of shrinkage factor in TD direction-Minimum value of shrinkage factor in MD direction | ≦ 0.6% (2)

  According to the present invention, it is possible to provide a polyester film for a surface protection film which has thermal properties that exhibit excellent handling properties and processability, and the industrial value of the present invention is high.

  The optical laminated polyester film of the present invention is preferably a multilayer film of at least three or more layers. The laminated polyester film for optics referred to in the present invention is a polyester film extruded by a so-called extrusion method which is melt-extruded from an extrusion die, and if necessary, oriented in biaxial directions of longitudinal direction and lateral direction Film.

The base film of the present invention is made of polyester. Such polyesters include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, sebacic acid, 4,4'-diphenyldicarboxylic acid, dicarboxylic acids such as 1,4-cyclohexyldicarboxylic acid, or esters thereof A polyester produced by melt polycondensation of ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, and glycol such as 1,4-cyclohexanedimethanol. The polyester comprising the acid component and the glycol component can be produced by optionally using a commonly used method.
For example, a bis-glycol of a substantially aromatic dicarboxylic acid by transesterification between a lower alkyl ester of an aromatic dicarboxylic acid and a glycol or directly esterifying an aromatic dicarboxylic acid and a glycol A method is employed in which an ester, or a low polymer thereof, is formed, and then this is heated to polycondense under reduced pressure. Depending on the purpose, aliphatic dicarboxylic acids may be copolymerized.

  Typical examples of the polyester of the present invention include polyethylene terephthalate, polyethylene-2,6-naphthalate, poly-1,4-cyclohexanedimethylene terephthalate and the like, and in addition, the above acid component and glycol component may be used together. It may be a polymerized polyester, and may contain other components and additives as required.

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

  On the other hand, the shape of the particles to be used is not particularly limited either, and any of spherical, massive, rod-like, flat and the like may be used. Also, there is no particular limitation on the hardness, specific gravity, color and the like.

  The particle size and content of the particles used are selected according to the application and purpose of the film, but the average particle size is usually in the range of 0.01 to 5.0 μm. If the average particle size exceeds 5.0 μm, the surface roughness of the film may be too rough, or the particles may be easily detached from the film surface. If the average particle size is less than 0.01 μm, the surface roughness may be too small to obtain sufficient slipperiness, and the polyester film may not be adjusted to the desired haze range.

  The type of particle type to be used is not particularly limited and may be selected according to the application and purpose of the film. From the viewpoint of imparting slipperiness, the particles to be added are preferably added to the outermost layer of the polyester film.

  Furthermore, the particle content in the polyester layer is usually in the range of 0.0005 to 0.5% by weight, preferably 0.001 to 0.3% by weight. When the particle content is less than 0.0005% by weight, the slipperiness of the film may be insufficient and appearance defects such as scratches may occur during film processing. On the other hand, when it is added in an amount of more than 0.5% by weight, aggregation of particles may occur, and there is a high possibility that defects in quality such as fish eyes may occur in the polyester film.

  The polyester of the film of the present invention preferably has a haze of 20% or less, more preferably 15% or less, and still more preferably 10% or less. When the haze is greater than 20%, the testability tends to be poor due to the haze of the laminate and the like in the inspection after preparing the surface protective film / transparent conductive film laminate using the film of the present invention .

  30 nm or less of the surface roughness (Ra) of the film of the film of this invention is preferable, More preferably, it is 20 nm or less. When the surface roughness (Ra) exceeds 30 nm, when the surface protective film is peeled off after the surface protective film / transparent conductive film laminate is formed, the surface of the adhesive layer is roughened, and the unevenness results in the final product In the image of the electronic display incorporating the transparent conductive film, defects such as distortion and blurring may occur.

  In the present invention, various stabilizers, lubricants, antistatic agents, ultraviolet light absorbers and the like can be added to the film as appropriate.

  The thickness of the polyester film of the present invention is essentially 100 μm or more, and more preferably 125 μm or more. When the film thickness is less than 100 μm, the thickness of the laminate after bonding to the transparent conductive film is not sufficient, so that wrinkles may occur during processing, or a defect may occur when the laminate is cut into sheets. It may occur, or the stability of the laminate cut into pieces may be insufficient. When the thickness is 350 μm or more, the strength of the film becomes too strong, and the laminate after being bonded to the transparent conductive film is unrolled from the roll form and has problems such as curling and curling when actually used It may occur and cause problems in practical use.

In the polyester film of the present invention, the relationship between the shrinkage factor of the film in the MD direction and that in the TD direction after heating at 150 ° C. for 30 minutes at 100 mm intervals in the TD direction satisfies the following formula (1) or (2) To be a necessary condition.
| Maximum contraction rate in the MD direction-minimum contraction rate in the TD direction | ≦ 0.6% (1)
| Maximum value of shrinkage factor in TD direction-Minimum value of shrinkage factor in MD direction | ≦ 0.6% (2)

  More preferably, the absolute value of the maximum value of shrinkage in the MD direction divided by the minimum value of shrinkage in the TD direction or the maximum value of the shrinkage in the TD direction divided by the minimum value of the shrinkage in the MD direction The absolute value of the value is 0.4% or less.

  The absolute value of the maximum value of contraction rate in the MD direction divided by the minimum value of contraction rate in the TD direction, or the absolute value of the maximum value of contraction rate in the TD direction divided by the minimum value of contraction rate in the MD direction When the film of the present invention is used as a substrate of a surface protective film to form a laminate bonded to a transparent conductive film, when heat treatment is performed as a crystallization step of the conductive layer, Curling occurs in the laminate, the amount of change in shape is large, and there is a high possibility that appearance defects such as generation of flaws due to contact between members and equipment in the heating furnace may occur.

As a film forming method of the film of the present invention, a generally known film forming method can be adopted, and there is no particular limitation. For example, first, a sheet obtained by melt extrusion is stretched by 2 to 6 times at 70 to 145 ° C. by roll stretching to obtain a uniaxially stretched polyester film, and then, in a tenter, it is perpendicular to the above stretching direction. A film is obtained by extending | stretching 2 to 6 times at 80-160 degreeC in a direction, and heat-processing further at 150-250 degreeC for 1 to 600 seconds. Furthermore, in this case, a method of relaxing by 0.1 to 20% in the longitudinal direction and / or the transverse direction in the heat treatment zone and / or the cooling zone at the heat treatment outlet is preferable.

  In the laminated polyester film for optics of the present invention, a coated layer may be provided for the purpose of improving the adhesion with the layer to be processed thereon, improving the slipperiness during processing, and the like. With regard to the coated layer, an in-line coating may be provided to treat the film surface during the film forming process of the polyester film, or an off-line coating may be employed which is applied outside the film on the film once produced. In-line coating is preferably used because it can be applied at the same time as film formation, so that manufacturing can be performed inexpensively.

  About in-line coating, although not limited to the following, for example, in the sequential biaxial stretching, a coating process can be applied before transverse stretching in which longitudinal stretching is completed. When the coating layer is provided on the polyester film by in-line coating, the coating can be performed simultaneously with the film formation, and the coating layer can be treated at a high temperature in the heat treatment step of the polyester film after stretching. It is possible to improve the performances such as adhesion to various surface functional layers that may be formed on the layer and moisture and heat resistance. Moreover, when coating is performed before extending | stretching, the thickness of a coating layer can also be changed with a draw ratio, and compared with off-line coating, uniform coating can be performed by a thin film. That is, the film suitable as a polyester film can be manufactured by in-line coating, especially the coating before extending | stretching.

  In addition, the coating layer of the film of the present invention may be a surfactant, an antifoamer, a coatability improver, a thickener, an organic lubricant, an organic particle, an inorganic particle, an antioxidant, an ultraviolet absorber, a foaming agent, You may contain additives, such as a dye and a pigment. These additives may be used alone or in combination of two or more as needed.

The coating agent may contain a small amount of an organic solvent for the purpose of improving the dispersion in water or improving the film forming performance as long as water is the main medium. It is necessary to use the organic solvent in the range which melt | dissolves 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 and 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, and amides such as N-methyl pyrrolidone It can be mentioned.
These organic solvents may be used in combination of two or more as needed.

  Further, if necessary, heat treatment and active energy ray irradiation such as ultraviolet irradiation may be used in combination regardless of off-line coating or in-line coating. 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 single-sided or double-sided. The material of the coating may be either water-based and / or solvent-based for off-line coating, but water-based or aqueous dispersion is preferred for in-line coating.

  In addition, when the polyester film of the present invention is used for optics, a coloring agent, a conductive material, etc. may be added, and further, reflection of external light, electric shock due to static electricity, dust adhesion prevention, and further electromagnetic wave shielding A targeted functional multilayer thin film may be formed.

  The coating solution used in the present invention is preferably an aqueous solution or an aqueous dispersion in terms of handling and working environment, but water is the main medium and if it does not exceed the scope of the present invention, it contains an organic solvent. It may be done.

  The solid content concentration of the coating solution is not particularly limited, but is usually 0.3 to 65% by weight, preferably 0.5 to 30% by weight, and more preferably 1 to 20% by weight. If the concentration is too high or too low in these ranges, it may be difficult to provide a coating of the required thickness to fully develop the function.

  The thickness of the coating layer is a dry thickness, usually 0.003 to 1.5 μm, preferably 0.01 to 0.5 μm, and more preferably 0.01 to 0.3 μm. 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 the films is likely to occur.

  As a coating method of the coating agent, for example, a reverse roll coater, a gravure coater, a rod coater, a rod coater, an air doctor coater or any other coating device as shown in "Coating method" by Harazaki Yuji, Aoi Shoten, published in 1979, "Coating method" Can be used.

  In the present invention, in order to further improve slipperiness, adhesion and the like, it is preferable to incorporate inorganic particles and organic particles in the coating layer. The compounding amount of the particles in the coating agent is usually 0.5 to 10% by weight, preferably 1 to 5% by weight. If the compounding amount is less than 0.5% by weight, the blocking resistance may be insufficient, and if it exceeds 10% by weight, the transparency of the film tends to be impaired 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, antimony oxide and the like. 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 containing two or more carbon-carbon double bonds in one molecule (for example, divinylbenzene).

The above-mentioned inorganic particles and organic particles may be surface-treated. As a surface treatment agent, surfactant, polymer | macromolecule as a dispersing agent, a silane coupling agent, a titanium coupling agent etc. are mentioned, for example. The content of the particles in the coating layer is preferably 10% by weight or less, more preferably 5% by weight or less, as a suitable addition amount that does not inhibit the transparency.
In addition, the coating layer may contain an antifoamer, a coatability improver, a thickener, an antioxidant, an ultraviolet absorber, a foaming agent, a dye, a pigment, and the like.

  The polyester film of the present invention has an adhesive layer coated on one side and used as a surface protective film. In addition, a release layer is usually provided below the adhesive layer. The material constituting the release layer is not particularly limited as long as it has releasability, and may be of a type containing a curable silicone resin as a main component, or an organic compound such as a urethane resin, an epoxy resin or an alkyd resin. You may use the modified silicone type etc. by the graft polymerization etc. with resin. Among them, when a curable silicone resin is used as a main component, it is good in terms of good releasability. As the type of curing type silicone resin, any curing reaction type such as solvent addition type, solvent condensation type, solvent ultraviolet curing type, non-solvent addition type, non solvent condensation type, non solvent ultraviolet curing type, non solvent electron beam curing type It can be used.

  The material constituting the adhesive layer is not particularly limited as long as it has adhesiveness, and preferred examples thereof include acrylic resins, olefin resins, urethane resins, and polyether resins. Although vinyl acetate resins, ethylene-vinyl acetate resins, epoxy resins, vinyl chloride resins, polyamide resins and the like can be mentioned, acrylic resins which can be easily adjusted in adhesion are particularly preferably used. The thickness of the adhesive layer is not particularly limited, but is usually in the range of 1 to 100 μm, preferably 2 to 50 μm, and more preferably 2 to 30 μm. If the thickness is less than 1 μm, sufficient adhesion may not be obtained. If the thickness is more than 100 μm, the ratio of the adhesive layer to the entire surface protective film / transparent conductive film laminate is too high, and the stability as a laminate May be lacking.

  The surface protection film using the polyester film of the present invention as a substrate is bonded to a transparent conductive film via an adhesive layer and used as a surface protection film / transparent conductive film laminate, but the transparent conductive film is generally used. Has a configuration in which a conductive film is laminated on a transparent substrate. The transparent substrate is not particularly limited as long as sufficient transparency, dimensional stability, mechanical properties, heat resistance and the like are secured, but as its material, polyester, polyacrylic, polycarbonate, tri-ester is generally used. Acetyl cellulose, aliphatic cyclic polyolefin and the like are preferably used. The thickness of the substrate of the transparent conductive film is not particularly limited, but is usually in the range of 5 to 100 μm, preferably 7 to 50 μm, and more preferably 10 to 30 μm. If the thickness is less than 5 μm, wrinkles and the like may be easily formed during processing of the transparent conductive layer coating, and processability may be lacking. If the thickness is more than 100 μm, productivity at the time of transparent film coating is poor.

As a constituent material of the transparent conductive film, metal oxides are suitably used from the viewpoints of transparency, durability, and weather resistance, and particularly indium tin oxide (ITO), antimony-containing indium tin compound (ATO), oxidation Tin, zinc oxide (ZnO), indium zinc oxide (In ₂ O ₃ -ZnO) and the like are particularly preferably used. The method of forming the transparent conductive film is not particularly limited, and a conventionally known method can be employed. Specifically, a vacuum evaporation method, a sputtering method, an ion plating method and the like can be mentioned.

  EXAMPLES The present invention will be described in more detail by way of examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. In addition, the evaluation method in an Example and a comparative example is as follows.

(1) Measurement of Intrinsic Viscosity of Polyester Weigh precisely 1 g of polyester from which other polymer components and pigments incompatible with polyester have been removed, and add 100 ml of mixed solvent of phenol / tetrachloroethane = 50/50 (weight ratio) It was dissolved and measured at 30 ° C.

(2) Average particle diameter of particles added to polyester film (d 50)
The particle size was measured by a sedimentation method based on Stokes's resistance law, using a centrifugal sedimentation type particle size distribution measuring apparatus SA-CP3 manufactured by Shimadzu Corporation.

(3) Thickness of Polyester Film The thickness of the polyester film was measured using a Digimatic standard outer micrometer (MDC-SB) manufactured by Mitutoyo Corporation.

(4) Shrinkage of polyester film Sample films were collected from polyester film roll at intervals of 100 mm in the width direction, heat-treated for 30 minutes in an oven kept at a predetermined temperature (150 ° C) without tension, and before and after The length of the sample was measured and calculated by the following equation. In addition, it measured about each of MD direction MD of a film, and TD direction, and calculated | required the maximum value and minimum value from the measured value of all the sample samples of MD direction and the direction of TD direction, respectively.
Shrinkage rate = {(sample length before heat treatment) − (sample length after heat treatment)} / (sample length before heat treatment) × 100

(5) Measurement of Film Haze According to JIS-K-7136, the film haze of the sample film was measured using a haze meter "HM-150" manufactured by Murakami Color Research Laboratory.

(6) Surface roughness (Ra) of polyester film
Parallel to the average line of the part (hereinafter referred to as the extracted part) extracted by a reference length (2.5 mm) from the cross-sectional curve obtained by Kosaka Research Institute Co., Ltd. surface roughness measuring machine “SE-3F” When the drawn portion is sandwiched by straight lines, the distance between the two straight lines is measured in the direction of the longitudinal magnification of the cross-sectional curve, and the value expressed in micrometers (μm) is taken as the maximum height of the drawn portion. The maximum height was obtained by determining 10 cross-sectional curves from the sample film surface and expressing the average value of the maximum heights of the removed portions determined from these cross-sectional curves. 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.

(7) Coating of release layer and adhesive layer on polyester film
An anchor layer composed of the following anchor layer composition was coated on a polyester film so that the coating amount (after drying) was 0.05 g / m 2, and then dried at 120 ° C. for 30 seconds. Next, on the anchor layer, 100 parts of a curable silicone resin ("KS-779H" manufactured by Shin-Etsu Chemical Co., Ltd.), 1 part of a curing agent ("CAT-PL-8" manufactured by Shin-Etsu Chemical), methyl ethyl ketone (MEK) / toluene mixed solvent system A release agent consisting of 2200 parts was applied to a coating amount of 0.1 g / m ² and dried at 170 ° C. for 10 seconds to obtain a release film.

<< Anchor layer composition >>
Aluminum tris (acetylacetonate): 19.5% by weight
· Γ-Glycidoxypropyltrimethoxysilane: 80% by weight
-Dibutyltin diacetate: 0.5% by weight

Thereafter, a pressure-sensitive adhesive layer comprising the following pressure-sensitive adhesive layer composition is applied to the surface of the polyester film which has been subjected to release treatment so that the thickness (after drying) becomes 25 μm and dried at 100 ° C. for 5 minutes. Obtained.
(Adhesive layer composition)
A solution of an acrylic copolymer having a weight average molecular weight of 600,000 (in terms of polystyrene) copolymerized (solid content: 30%) by copolymerizing butyl acrylate (100 parts by weight, 6 parts by weight of acrylic acid) in ethyl acetate by a conventional method. %) Got. To 100 parts by weight (solid content) of an acrylic copolymer, 0.2 parts by weight of N, N-dimethylaminoethyl acrylate and 6 parts by weight of tetrad C (manufactured by Mitsubishi Gas Chemical Co., Ltd.) which is an epoxy-based crosslinking agent are added. An adhesive layer composition was obtained.

(8) Processability of surface protective film / transparent conductive film laminate A 38 μm thick polyester film (Diafoil “T600E38”, manufactured by Mitsubishi Plastics Co., Ltd.) is used and 95% argon gas and 5% oxygen gas. In a 0.4 Pa atmosphere, a 25 nm thick ITO film (transparent conductive thin film) is formed by reactive sputtering using a sintered material of 95 wt% indium oxide and 5 wt% tin oxide. A conductive film was made. The surface of the transparent conductive film is disposed on the side opposite to the side on which the ITO film is formed so as to be in contact with the adhesive surface of the above-mentioned adhesive processed surface protective film, and is bonded. did. The obtained surface protective film / transparent conductive film laminate was cut into a size of 21 cm × 30 cm, made into a sheet, and heat treated at 180 ° C. for 1 hour to carry out crystallization treatment of the ITO film. The processability of the laminate was evaluated according to the following criteria. :: can be cut without cutting the film end to the cutter etc. when cutting the laminate sheet by sheet ×: sprinkling of the film end sticking to the cutter etc when cutting the laminate sheet by sheet, processability is improved bad

(9) Curling property of surface protective film / transparent conductive film laminate The surface protective film / transparent conductive film laminate of 21 cm × 30 cm size prepared as described above is set for 60 minutes in a hot air circulating furnace set at 180 ° C. Heat treat. Next, the sample was placed on a horizontal table, and the highest height of the heights of the four corners lifted from the horizontal surface was measured, and this value was taken as the maximum curl value.
(Judgment criteria)
○: Maximum curl value is 5 mm or less Δ: Maximum curl value exceeds 5 mm, 10 mm or less ×: Maximum curl value exceeds 10 mm

(10) Testability of surface protective film / transparent conductive film laminate The surface protective film / transparent conductive film laminate product after crystallization treatment prepared as described above is both transmitted in the dark room under irradiation of a three-wavelength fluorescent lamp in a dark room. Under the conditions, visual inspection was performed from the protective film side, and the inspection criteria were evaluated according to the following criteria.
○: No fogging is observed at the time of visual inspection, and sufficient inspection performance is ensured ×: The laminate is cloudy at the time of inspection at the time of visual inspection, and visual inspection is disturbed

(11) Evaluation of adhesive layer surface after peeling surface protective film The surface protective film of the surface protective film / transparent conductive film laminate prepared as described above is peeled, and the surface is irradiated with a three-wavelength fluorescent lamp in a dark room It observed under reflected light below and was evaluated by the following criteria.
:: The surface of the adhesive layer is not rough and sufficient flatness is ensured.
X: Since the surface of the adhesive layer is rough, irregular reflection of fluorescent lamp reflected light can be visually confirmed.

(Production method of polyester chip A)
100 parts of dimethyl terephthalate, 70 parts of ethylene glycol and 0.07 parts of calcium acetate monohydrate are put into a reactor, and heated and heated while distilling off methanol to carry out transesterification, and about 4 and a half hours are required after the reaction starts Then, the temperature was raised to 230 ° C. to substantially complete the transesterification reaction. Next, 0.04 parts of phosphoric acid and 0.035 parts of antimony trioxide were added, and polymerization was performed according to a conventional method. That is, the reaction temperature was gradually raised to 280 ° C., while the pressure was gradually reduced to 0.05 mmHg. After 4 hours, the reaction was terminated and chipped according to a conventional method to obtain polyester A.

(Production method of polyester chip B)
When producing the said polyester A, 6000 ppm of silica particles with an average particle diameter of 3.0 micrometers were added, and polyester B was obtained.

(Production method of polyester chip C)
When manufacturing the said polyester A, 5000 ppm of calcium carbonate with an average particle diameter of 0.8 micrometer was added, and the polyester C was obtained.

Example 1:
A mixture of 85% and 15% polyester A and polyester B is used as a raw material for layer A, and a mixture of 100% polyester A is used as a raw material for layer B and two extruders. And each melted at 285 ° C, two layers and three layers (ABA) on the casting drum cooled to 40 ° C with the A layer as the outermost layer (surface layer) and the B layer as the intermediate layer. The coextrusion was cooled and solidified so that the component ratio A: B: A = 5: 115: 5 to obtain a non-oriented sheet. Next, the film is stretched 3.4 times in the longitudinal direction at a film temperature of 85 ° C. using the roll peripheral speed difference, and then this longitudinally stretched film is guided to a tenter and stretched 4.0 times in the lateral direction at 120 ° C., 230 ° C. The resultant was heat-treated to obtain a polyester film master roll having a thickness of 125 μm and a total width of about 4 m. The polyester film of this invention was obtained by setting and slitting a slit blade in the position of 600 mm and 1800 mm at the width direction end side from the center part of the obtained polyester film master roll. The properties of the obtained polyester film are shown in Table 1 below.

Example 2:
A polyester film is prepared in the same manner as in Example 1 except that the slit blade of the obtained polyester film master roll is set at 600 mm on both ends with respect to the center of the polyester film master roll in Example 1. I got The properties of the obtained polyester film are shown in Table 1 below.

Example 3:
In Example 1, a polyester film was obtained in the same manner as in Example 1 except that the longitudinal stretching ratio was 3.6 times. The properties of the obtained polyester film are shown in Table 1 below.

Example 4:
A polyester film was obtained in the same manner as in Example 1 except that polyester A and polyester C were mixed at a ratio of 93% and 7% as a raw material of layer B in Example 1. The properties of the obtained polyester film are shown in Table 1 below.

Example 5:
In Example 1, coextrusion so that the film thickness composition ratio is A: B: A = 7.5 / 173 / 7.5, and the final thickness of the polyester film is 188 μm. A polyester film was obtained in the same manner as in Example 1 except that a film was formed.

Example 6:
In Example 1, polyester A and polyester B were mixed at a ratio of 80% and 20% as a raw material of layer A, and polyester A and polyester C were mixed at a ratio of 90% and 10% as a raw material for layer B A polyester film was obtained in the same manner as in Example 1. The properties of the obtained polyester film are shown in Table 1 below.

Reference Example 7 :
In Example 1, polyester A and polyester B were mixed at a ratio of 70% and 30% as a raw material for layer A, and polyester A and polyester C were mixed at a ratio of 95% and 5% as a raw material for layer B A polyester film was obtained in the same manner as in Example 1. The properties of the obtained polyester film are shown in Table 1 below.

Comparative Example 1:
In Example 1, a polyester film is prepared in the same manner as Example 1, except that the longitudinal stretching ratio is 3.8 times, the transverse stretching ratio is 3.9 times, and the heat treatment temperature after the transverse stretching step is 225 ° C. Obtained.

Comparative example 2:
In Example 1, the coextrusion was performed so that the thickness ratio of the film was A: B: A = 3: 69: 3, and the film was formed such that the thickness of the final polyester film was 75 μm. A polyester film was obtained in the same manner as Example 1 except for the above. The properties of the obtained polyester film are shown in Table 1 below.

  The film roll of the present invention can be suitably used as a polyester film for surface protection film, which is used by being bonded to a transparent conductive film.

Claims (2)

It is a polyester film with a thickness of 100 μm or more and a surface roughness (Ra) of 23 nm or less, and the film in the MD direction and TD direction after heating at 150 ° C. for 30 minutes at each 100 mm location in the film TD direction. A polyester film roll for surface protection film, wherein the shrinkage ratio satisfies the following formula (1) or (2), and the length of the film in the direction orthogonal to the MD direction is 1,000 mm or more.
| Maximum contraction rate in the MD direction-minimum contraction rate in the TD direction | ≦ 0.6% (1)
| Maximum value of shrinkage factor in TD direction-Minimum value of shrinkage factor in MD direction | ≦ 0.6% (2)   The polyester film which comprises the polyester film roll for surface protection films of Claim 1 is bonded with a conductive film via the adhesion layer, The laminated body characterized by the above-mentioned.