JP2014047271A - Polyester film, laminate polyester film, hard coat film, and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminate film capable of inhibiting both the yellowing and whitening of a polyester film and having a high adhesiveness between layers mediated by an adhesion-facilitating layer.SOLUTION: The provided polyester film is a polyester film on which a surface modification layer having a non-crystalline degree (non-crystallinity/crystallinity) of 5% or above has been formed; the surface modification layer is formed as the surface layer of the polyester film; the thickness of the surface modification layer coincides with a depth confined to a range of 40-330 nm from the surface of the polyester film; the b value of the polyester film is b=0.006t+0.55 or below.

Description

  The present invention relates to a polyester film, a laminated polyester film obtained by laminating an easy-adhesion layer on a polyester film, and a hard coat film having a laminated polyester film and a hard coat layer. Furthermore, this invention relates to the manufacturing method of these polyester films, laminated polyester films, and hard coat films.

  A laminated film formed by laminating a plurality of layers is often used as an optical film. Since the polyester film has excellent transparency and stability, it is preferably used as a support for optical films. The polyester film as the support is provided with a functional layer such as a hard coat layer in accordance with various uses, and becomes an optical film such as a hard coat film. In recent years, hard coat films are often used for touch panel applications.

  Generally, since a polyester film and a functional layer are comprised from a different component, it is difficult to adhere | attach both directly. For this reason, providing an easily bonding layer on a polyester film, and laminating | stacking functional layers, such as a hard-coat layer, on it has been proposed. For example, in Patent Document 1, an easy adhesion layer is laminated on a polyester film, and a hard coat layer is laminated on the easy adhesion layer to obtain a hard coat film.

  Conventionally, it is known that the surface of a polyester film is modified by subjecting the surface of the polyester film to surface treatment such as glow discharge treatment (for example, Patent Document 2). By performing the glow discharge treatment, the surface of the polyester film can be modified and the flatness can be improved. Further, the glow discharge treatment has an advantage that the adhesion of the laminated film can be improved. Patent Document 2 also describes that the glow discharge treatment must be performed at a temperature lower than the glass transition temperature (Tg) so that no curl or creaking occurs when winding into a roll.

JP 2007-203635 A Japanese Patent Laid-Open No. 9-230538

  However, as in Patent Document 1, when an easy-adhesion layer is provided on a polyester film and a functional layer such as a hard coat layer is laminated thereon, an oligomer contained in the polyester film is precipitated, and the polyester film is There is a problem of whitening. In a laminated film that requires transparency, whitening of the polyester film becomes a serious problem.

  Whitening of the polyester film is improved to some extent by performing glow discharge treatment on the surface of the polyester film. However, the glow discharge treatment described in Patent Document 2 has a problem that the effect of improving whitening is not sufficient.

Further, as in Patent Document 2, when glow discharge treatment is performed at less than Tg, the amount of glow discharge treatment must be increased to ensure adhesion, and the polyester film turns yellow (yellowing). There was a problem.
When the glow discharge treatment amount is increased in order to ensure adhesion, the polyester film turns yellow, and the adhesion cannot be ensured unless the glow discharge treatment amount is increased. That is, there is a trade-off relationship between suppressing yellowing of the polyester film and ensuring adhesion, and there is a problem that both problems cannot be solved simultaneously.

  Therefore, the present inventors provide a laminated film that can suppress both yellowing and whitening of the polyester film and has high adhesion between the respective layers of the laminated film in order to solve such problems of the prior art. The study was advanced as a purpose.

As a result of diligent studies to solve the above problems, the present inventors have found that both the yellowing and whitening of the polyester film can be suppressed by performing glow discharge treatment on the surface of the polyester film at Tg or higher. It was. That is, the inventors set the b value per unit thickness of the polyester film (L ^* a ^* b ^* b value of the color space of CIE 1976) to be within a certain range, and the amorphousness of the surface of the polyester film is more than a certain value. As a result, the present invention was completed by successfully obtaining a laminated film in which the adhesion between the easy-adhesion layer and the polyester film was high and both the yellowing and whitening of the polyester film were suppressed. Specifically, the present invention has the following configuration.

[1] A polyester film in which a surface-modified layer having an amorphous degree (non-crystallinity / crystallinity) of 5% or more is formed, wherein the surface-modified layer is formed as a surface layer of the polyester film, The surface modification layer has a thickness from the surface of the polyester film to any depth within a range of 40 to 330 nm, and the b value of the polyester film is b = 0.006t + 0.55 or less. Polyester film. (The t represents the thickness of the polyester film.)
[2] The polyester film [3] according to [1], wherein the surface modified layer has a thickness from the surface of the polyester film to any depth within a range of 50 to 220 nm. The polyester film according to [1] or [2], wherein the surface modification layer has an amorphous degree (non-crystalline degree / crystalline degree) of 5 to 8.3%.
[4] A laminated polyester film, wherein an easy-adhesion layer is laminated facing the surface modified layer of the polyester film according to any one of [1] to [3].
[5] A hard coat film, wherein a hard coat layer is laminated facing the easy-adhesion layer of the laminated polyester film according to [4].
[6] The hard coat film as described in [5], wherein the hard coat layer has a refractive index of 1.70 to 1.85.
[7] A touch panel comprising the hard coat film according to [5] or [6] and a transparent electrode layer.
[8] A method for producing a polyester film, comprising a step of performing glow discharge treatment on the surface of the polyester film heated to Tg or more (Tg means a glass transition temperature of the polyester film).
[9] The method for producing a polyester film according to [8], wherein the surface of the polyester film is heated to Tg to 200 ° C.
[10] The process according to [8] or [9], wherein in the step of performing the glow discharge treatment, a change amount (Δb) of the b value of the polyester film before and after the glow discharge treatment is set to 0.3 or less. Of manufacturing polyester film.
[11] A step of laminating an easy-adhesion layer on the surface of the polyester film produced by the method for producing a polyester film according to any one of [8] to [10] and having been subjected to a glow treatment. A method for producing a laminated polyester film characterized by the above.
[12] A hard coat layer is provided on the surface of the easy-adhesion layer of the laminated polyester film produced by the method for producing a laminated polyester film according to [11], which is opposite to the surface on which the polyester film is laminated. A method for producing a hard coat film, comprising a step of laminating.
[13] A polyester film produced by the production method according to any one of [8] to [10].
[14] A laminated polyester film produced by the production method according to [11].
[15] A hard coat film produced by the production method according to [12].
Film.

  According to the present invention, a polyester film in which both yellowing and whitening are suppressed can be obtained. Thereby, a highly transparent laminated polyester film and hard coat film can be obtained. The polyester film, laminated polyester film and hard coat film of the present invention are preferably used particularly for touch panel applications because both yellowing and whitening are suppressed and transparency is high.

  Moreover, according to this invention, the adhesiveness between each layer of a laminated | multilayer film can be improved. For example, in a hard coat film, the adhesiveness between each layer of a polyester film, an easily bonding layer, and a hard coat layer can be improved.

FIG. 1 is a TEM observation image of the surface of a polyester film. FIG. 2 is a schematic diagram illustrating a layer configuration of a laminated film for a touch panel. FIG. 3 is a graph showing the relationship between the film thickness of the polyester film and the b value.

Hereinafter, the present invention will be described in detail. The description of the constituent elements described below may be made based on representative embodiments and specific examples, but the present invention is not limited to such embodiments. In the present specification, a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.
Moreover, (meth) acrylate is used in the meaning containing both acrylate and methacrylate.

(Polyester film)
The polyester film in the present invention refers to a film whose main component is polyester, and usually refers to a film in which 98% by mass or more of the resin component is polyester, and preferably 90% by mass of the component constituting the polyester film is polyester. Is a film. The kind in particular of polyester is not restrict | limited, A well-known thing can be used as polyester. Specific examples include polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and polybutylene naphthalate. Among them, it is particularly preferable to use polyethylene terephthalate (PET) from the viewpoint of cost and mechanical strength.

  The polyester film in the present invention is preferably biaxially stretched. Biaxial stretching refers to stretching in both directions by regarding the width direction and the longitudinal direction of the film as uniaxial. Thus, the biaxially stretched polyester film has very good mechanical strength because the molecular orientation in the biaxial direction is sufficiently controlled. The draw ratio is not particularly limited, but the draw ratio in one direction is preferably 1.5 to 7 times, more preferably 2 to 5 times. In particular, a polyester film that has been biaxially stretched at a stretching ratio of 2 to 5 times per uniaxial direction has a very excellent mechanical strength because the molecular orientation is controlled more efficiently and effectively. Suitable as a film. By setting the draw ratio of the polyester film to 1.5 times or more, sufficient mechanical strength can be obtained as compared with the case of less than 1.5 times. Further, by setting the draw ratio to 7 times or less, a uniform thickness can be obtained as compared with the case where the draw ratio exceeds 7 times.

  The thickness of the polyester film is preferably 30 to 400 μm, and more preferably 100 to 250 μm. The polyester film in the present invention may consist of only one layer, or may be a laminate of two or more layers of polyester film (for example, co-flow film, co-extruded film, etc.). When the polyester film in this invention consists of two or more layers, the total thickness becomes the said range.

  The polyester film according to the present invention has a surface modified layer. A surface modified layer is a layer formed in the surface layer of a polyester film, Comprising: The non-crystallinity (non-crystallinity / crystallinity) mentioned later means a layer 5% or more. The surface modification layer has a thickness from the surface of the polyester film to any depth within the range of 40 to 330 nm. The surface modification layer preferably has a thickness up to any depth within the range of 330 nm, more preferably within the range of 50 to 220 nm, and within the range of 50 to 200 nm. Further preferred.

The surface of the polyester film is preferably subjected to glow discharge treatment. By performing glow discharge treatment by heating to a temperature equal to or higher than Tg, a surface modified layer can be easily formed on the surface layer of the polyester film.
The glow discharge treatment is a method called vacuum plasma treatment or glow discharge treatment, in which plasma is generated by discharge in a gas (plasma gas) in a low-pressure atmosphere to treat the substrate surface. The low-pressure plasma used in the process of the present invention is a non-equilibrium plasma generated under conditions where the plasma gas pressure is low. The treatment of the present invention is performed by placing a film to be treated in this low-pressure plasma atmosphere.
In the glow discharge treatment of the present invention, as a method for generating plasma, methods such as direct current glow discharge, high frequency discharge, and microwave discharge can be used. The power source used for discharging may be direct current or alternating current. When alternating current is used, a range of about 30 Hz to 20 MHz is preferable. When alternating current is used, a commercial frequency of 50 or 60 Hz may be used, or a high frequency of about 10 to 50 kHz may be used. A method using a high frequency of 13.56 MHz is also preferable.

  As the plasma gas used in the glow discharge treatment of the present invention, an inorganic gas such as oxygen gas, nitrogen gas, water vapor gas, argon gas, helium gas can be used, and in particular, oxygen gas or oxygen gas and argon gas The mixed gas is preferable. Specifically, it is desirable to use a mixed gas of oxygen gas and argon gas. When oxygen gas and argon gas are used, the ratio between the two is preferably about oxygen gas: argon gas = 100: 0 to 30:70, more preferably 90:10 to 70:30, as a partial pressure ratio. In addition, a method is also preferable in which a gas such as the atmosphere entering the processing container due to leakage or water vapor coming out of the object to be processed is used as the plasma gas without introducing the gas into the processing container.

As the pressure of the plasma gas, a low pressure at which non-equilibrium plasma conditions are achieved is necessary. The specific plasma gas pressure is preferably in the range of about 0.005 to 10 Torr, more preferably about 0.008 to 3 Torr. When the pressure of the plasma gas is less than 0.005 Torr, the effect of improving adhesiveness may be insufficient. Conversely, when the pressure exceeds 10 Torr, the current may increase and the discharge may become unstable.
The plasma output cannot be generally specified depending on the shape and size of the processing vessel, the shape of the electrode, and the like, but is preferably about 100 to 10000 W, more preferably about 2000 to 10000 W.

  The treatment time of the glow discharge treatment of the present invention is preferably 0.05 to 100 seconds, more preferably about 0.5 to 30 seconds. If the treatment time is less than 0.05, the adhesion improving effect may be insufficient. Conversely, if the treatment time exceeds 100 seconds, problems such as deformation and coloring of the film to be treated may occur.

Discharge treatment intensity of the glow discharge treatment of the present invention will depend on the plasma power and treatment time, preferably in the range of 0.01~10kV · A · min / m ^2, 0.1~7kV · A · min / m ² Gayori preferable.
Discharge treatment intensity that is sufficient adhesion improving effect of the 0.01 kV · A · min / m ² or more is obtained, and such deformation and coloration of the processed film by a 10 kV · A · min / m ² or less You can avoid problems.

  In the glow discharge treatment of the present invention, it is preferable to heat a polyester film that is a film to be treated in advance. The surface of the polyester film is preferably subjected to glow discharge treatment at a temperature equal to or higher than Tg and then subjected to glow discharge treatment. That is, during the glow discharge treatment, the surface of the polyester film is preferably heated to Tg (69 ° C.) or higher. The surface of the polyester film is more preferably heated within a temperature range of Tg to 200 ° C, and more preferably heated within a temperature range of Tg to 150 ° C. By performing the glow discharge treatment after heating within the above temperature range, it is possible to prevent the oligomer from being deposited on the polyester film and to prevent the polyester film from being whitened. Furthermore, it can suppress that a polyester film yellows by performing a glow discharge process after heating in the said temperature range.

  Specific methods for raising the temperature of the film to be treated in vacuum include heating with an infrared heater, heating method by contacting with a hot roll, and the like.

The surface modified layer of the polyester film has an amorphous degree (non-crystalline degree / crystalline degree) of 5% or more. The non-crystallinity indicates the ratio of the non-crystalline part to the total of the non-crystalline part and the crystal part (content ratio of the non-crystalline part). The non-crystal part contains many Gauche crystal molecules, and the crystal part contains many trans-type crystal molecules. For this reason, the content rate of the non-crystal part and the crystal part can be calculated by the content rate of the crystal molecules. Specifically, the content ratio of the amorphous part and the crystalline part can be calculated by obtaining the spectrum of the surface modified layer by the ATR-IR method. A value obtained by dividing the amorphous degree (1175 cm ⁻¹ ) by the spectrum of the crystallinity spectrum (1341 cm ⁻¹ ) was defined as the amorphous degree (non-crystalline degree / crystalline degree).

  The non-crystallinity (non-crystallinity / crystallinity) of the surface modified layer of the polyester film is preferably 5% or more, more preferably 5 to 8.3%, and more preferably 5 to 8%. Further preferred. By setting the non-crystallinity of the surface modified layer within the above range, the oligomer block property and adhesion can be improved while preventing yellowing.

  In the polyester film according to the present invention, the b value of the polyester film is b = 0.006t + 0.55 or less. The b value is preferably b = 0.006t + 0.38 or less, more preferably b = 0.006t + 0.25 or less. In the above formula, t represents the thickness of the polyester film. By making b value below into the said formula, yellowing of a polyester film can be prevented and the transparency of a polyester film can be improved.

  For example, in a polyester film having a thickness of 200 μm, the b value of the polyester film is preferably 1.75 or less, more preferably 1.58 or less, and even more preferably 1.45 or less. Although the film thickness of the polyester film used by this invention is not specifically limited, When the film thickness of a polyester film is 100 micrometers, it is preferable that b value is 1.15 or less, and it is 1.0 or less. Is more preferable and 0.85 or less is still more preferable.

  Furthermore, a small b value after the glow discharge treatment indicates that no yellowing has occurred after the glow discharge treatment. In this invention, the polyester film in which yellowing was suppressed can be obtained by making b value in a glow discharge process into the said formula or less.

In FIG. 1, the TEM observation image showing the surface state of the polyester film which concerns on invention is shown. Fig.1 (a) has shown the TEM observation image of the surface of the polyester film which has not performed the glow discharge process. FIG.1 (b) has shown the TEM observation image of the surface of the polyester film which performed the glow discharge process. A portion indicated by an arrow in FIGS. 1A and 1B is the surface of the polyester film. In FIG. 1B, it can be seen that the range indicated by A is discolored black. This represents the surface modified layer. As can be seen from FIG. 1A, the polyester film not subjected to the glow discharge treatment does not have a surface modified layer. The thickness of the surface modified layer is the distance indicated by A in FIG. 1B, and the average value of the distance indicated by the arrow and A is referred to as the thickness of the surface modified layer.
The thickness of the surface modification layer can be determined by osmium staining the PET surface and observing a cross-section TEM. It is said that the portion where the chromaticity is L = 30 or less is dyed black, and this is a modified portion. In the untreated case (FIG. 1 (a)), nothing can be seen, but it can be seen that the surface is stained black when the glow treatment is performed (FIG. 1 (b)).

  The polyester film for optical use preferably has a refractive index of 1.63 to 1.71 and more preferably 1.62 to 1.68 because of transparency.

  The polyester film may contain other additives as long as they do not depart from the spirit of the present invention, and examples thereof include antioxidants and ultraviolet inhibitors.

(Easily adhesive layer)
The easy adhesion layer is laminated so as to be in contact with the polyester film, and the surface of the polyester film is laminated so as to face the surface modified layer subjected to the glow discharge treatment. That is, it is laminated so as to be in contact with the surface modified layer. The laminated polyester film of the present invention refers to a laminated film in which an easy adhesion layer is laminated so as to be in contact with the polyester film. In this invention, since the glow discharge process is given to the surface of the polyester film, the adhesiveness of a polyester film and an easily bonding layer is favorable.

  The easy-adhesion layer contains polyolefin, polyacryl, polyurethane, polyester, rubber-based resin, or the like as a binder in order to improve the adhesion to the polyester film. The binder of the easy-adhesion layer is preferably 30% by mass or more of polyolefin, preferably 50% by mass or more is polyolefin, and more preferably 90% by mass or more is polyolefin. The elastic modulus of the easy adhesion layer is preferably 50 MPa to 5 GPa, more preferably 100 MPa to 1 GPa.

  A polyolefin having a polar group such as a carboxyl group is preferred as an ionomer of a polyolefin having a polar group. It may be used by dissolving in an organic solvent, or an aqueous dispersion may be used. However, since the environmental load is small, it is preferable to attach with an aqueous system using an aqueous dispersion. A commercially available product may be used as the aqueous dispersion and is not particularly limited. Examples of those that can be preferably used in the present invention include Chemipearl S75N (manufactured by Mitsui Chemicals), Arrow Base SE1200. Arrowbase SB1200 (manufactured by Unitika Ltd.), Hitech S3111, S3121 (manufactured by Toho Chemical Co., Ltd.), and the like. Only one type of polyolefin may be included, or two or more types may be included.

As polyacryl, it is obtained by copolymerizing the monomer illustrated below. That is, alkyl acrylate, alkyl methacrylate (alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, 2-ethylhexyl, cyclohexyl, etc.); Hydroxy-containing monomers such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate and 2-hydroxypropyl methacrylate; Epoxy group-containing monomers such as glycidyl acrylate, glycidyl methacrylate and allyl glycidyl ether; acrylic acid and methacrylic acid Carboxylic acids such as itaconic acid, maleic acid, fumaric acid, crotonic acid, styrene sulfonic acid and its salts (sodium salt, potassium salt, ammonium salt, tertiary amine salt, etc.) A monomer having a group or a salt thereof; acrylamide, methacrylamide, N-alkyl acrylamide, N-alkyl methacrylamide, N, N-dialkyl acrylamide, N, N-dialkyl methacrylate (the alkyl group includes a methyl group, an ethyl group, n -Propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, 2-ethylhexyl group, cyclohexyl group, etc.), N-alkoxyacrylamide, N-alkoxymethacrylamide, N, N-dialkoxyacrylamide, N , N-dialkoxymethacrylamide (alkoxy groups include methoxy, ethoxy, butoxy, isobutoxy, etc.), acryloylmorpholine, N-methylolacrylamide, N-methylolmethacrylamide, N-phenol Monomers having an amide group such as ruacrylamide and N-phenylmethacrylamide; monomers of acid anhydrides such as maleic anhydride and itaconic anhydride; 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline Oxazolines such as 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, 2-isopropenyl-5-methyl-2-oxazoline Group-containing monomers: methoxydiethylene glycol methacrylate, methoxypolyethylene glycol methacrylate, vinyl isocyanate, allyl isocyanate, styrene, α-methylstyrene, vinyl methyl ether, vinyl ethyl ether, vinyl trialkoxysilane, alkyl maleic acid Monoester, alkyl fumaric acid monoesters, alkyl itaconic acid monoester, acrylonitrile, methacrylonitrile, vinylidene chloride, ethylene, propylene, vinyl chloride, vinyl acetate, butadiene.
Polyacrylic has a glass transition temperature of preferably −50 to 120 ° C., more preferably −30 to 100 ° C. The weight average molecular weight of polyacryl is preferably 3000 to 1000000.

  The polyurethane includes a polyol, a polyisocyanate, a chain extender, a crosslinking agent, and the like. Examples of polyols include polyoxyethylene glycol, polyoxypropylene glycol, polyethers such as polyoxytetramethylene glycol, polyethylene adipate, polyethylene-butylene adipate, polycaprolactone, and the like by a dehydration reaction of dicarboxylic acid. There are polyesters to be produced, polycarbonates having carbonate bonds, acrylic polyols, castor oil and the like. Examples of polyisocyanates include tolylene diisocyanate, phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, isophorone diisocyanate, and the like. Examples of chain extenders or crosslinking agents include ethylene glycol, propylene glycol, diethylene glycol, trimethylolpropane, hydrazine, ethylenediamine, diethylenetriamine, triethylenetetramine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodicyclohexylmethane, Water etc. are mentioned.

  As polyester, the polyester obtained from the following polybasic acid component and diol component can be used. That is, as the polyvalent base component, for example, terephthalic acid, isophthalic acid, phthalic acid, phthalic anhydride, 2,6-naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, adipic acid, sebacic acid, trimellitic acid, Examples include pyromellitic acid, dimer acid, and 5-sodium sulfoisophthalic acid. As the polyester constituting the polymer binder, it is preferable to use a copolymerized polyester using two or more kinds of dicarboxylic acid components. The polyester may contain an unsaturated polybasic acid component such as maleic acid or itaconic acid, or a hydroxycarboxylic acid component such as p-hydroxybenzoic acid, if it is in a slight amount.

  Polyester diol components include ethylene glycol, 1,4-butanediol, diethylene glycol, dipropylene glycol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, xylene glycol, dimethylolpropane, and the like, poly (ethylene oxide) ) Glycol and poly (tetramethylene oxide) glycol.

  The thickness of the easy-adhesion layer is preferably 30 to 150 nm, and more preferably 65 to 110 nm in order to further develop the adhesiveness to the polyester film. By setting the film thickness of the easy adhesion layer to 30 nm or more, the adhesion between the polyester film and the easy adhesion layer tends to be further improved. By setting the thickness of the easy adhesion layer to 150 nm or less, the surface state of the easy adhesion layer tends to be further improved. Moreover, when using the laminated | multilayer film of this invention as a hard coat film, the viewpoint of the effective suppression of a rainbow nonuniformity has the further more preferable thickness of 70-100 nm.

The easy adhesion layer includes fine particles. By including the fine particles, the refractive index of the easy-adhesion layer can be adjusted. The laminated film and hard coat film of the present invention are preferably used for touch panel applications, but in the touch panel applications, the adjustment of the refractive index is extremely important.
The refractive index n ₁ of the easy-adhesion layer preferably satisfies n _PE ≧ n ₁ when the refractive index of the polyester film is n _PE . The refractive index of the easy adhesion layer is preferably from 1.50 to 1.68, more preferably from 1.57 to 1.62.

The fine particles blended in the easy-adhesion layer preferably contain fine particles mainly composed of at least one of tin oxide, zirconium oxide, and titanium oxide. Here, the main component means a component having the largest blending amount contained in the fine particles, and usually means 80% by mass or more.
For example, the tin oxide is preferably tin (IV) oxide having a SnO ₂ composition. The use of tin oxide doped with antimony or the like is preferable because it has conductivity, and therefore the effect of reducing the surface resistivity of the laminated film and preventing impurities such as dust from adhering can be obtained. Specific examples of such antimony-doped tin oxide include commercially available FS-10D, SN-38F, SN-88F, SN-100F, TDL-S, and TDL-1 (all of which are Ishihara Sangyo ( Etc.), and the like can also be suitably used in the present invention.

The zirconium oxide has a composition of ZrO ₂ , and examples thereof include NZS-20A, NZS-30A (both manufactured by Nissan Chemical Co., Ltd.) and SZR-CW (manufactured by Sakai Chemical Industry Co., Ltd.), These can also be suitably used in the present invention.
As the titanium oxide, titanium (IV) oxide having a TiO ₂ composition is preferably used. Titanium oxide has a rutile type (tetragonal high-temperature type), anatase type (tetragonal low-temperature type), etc. depending on the difference in crystal structure, but is not particularly limited. Further, titanium oxide subjected to surface treatment may be used. Examples of titanium oxide that can be suitably used in the present invention include IT-S, IT-O, IT-W (all manufactured by Idemitsu Kosan Co., Ltd.), TTO-W-5 (Ishihara Sangyo Co., Ltd.). Manufactured) and the like.

The average particle size of the fine particles as described above is preferably 5 to 200 nm. When the average particle size of the fine particles is 200 nm or less, the influence of light being scattered by the fine particles is reduced, and it is difficult to become an obstacle, and when the average particle size is 5 nm or more, the fine particles are less likely to aggregate and become large. The average particle size of the fine particles in the present invention refers to particles obtained for any 50 fine particles when the particle size is the diameter of a circle having the same area as the fine particles when the fine particles are taken with a scanning electron microscope. The average size.
The compounding amount of the fine particles in the easy-adhesion layer is determined according to the refractive index, and can be, for example, 20 to 400 parts by mass with respect to 100 parts by mass of the binder component. From the standpoint of maintaining the brittleness of the film. Only one type of fine particles may be blended in the easy adhesion layer, or two or more types may be used. The easy-adhesion layer in the present invention preferably occupies 80% by mass or more of the constituent components of the easy-adhesion layer with the binder and fine particles.

  The easy-adhesion layer may contain a crosslinking agent, a matting agent, a surfactant, an antistatic agent, a slipping agent, etc., if necessary, in addition to the binder and fine particles.

<Crosslinking agent>
Examples of the crosslinking agent include epoxy-based, isocyanate-based, melamine-based, carbodiimide-based, and oxazoline-based crosslinking agents. Among these, a carbodiimide type crosslinking agent and an oxazoline type crosslinking agent are preferable.

  As the carbodiimide-based crosslinking agent, a compound having a plurality of carbodiimide structures in the molecule is preferable. By including such a compound, the adhesion between the hard coat layer and the easy-adhesion layer tends to be improved when the hard coat layer is provided. A compound having a plurality of carbodiimide groups in the molecule can be used without particular limitation. Polycarbodiimide is usually synthesized by condensation reaction of organic diisocyanate, but the organic group of the organic diisocyanate used in this synthesis is not particularly limited, either aromatic or aliphatic, or a mixture thereof It can be used. However, aliphatic systems are particularly preferred from the viewpoint of reactivity. As the synthetic raw material, organic isocyanate, organic diisocyanate, organic triisocyanate and the like are used.

  As examples of organic isocyanates, aromatic isocyanates, aliphatic isocyanates, and mixtures thereof can be used. Specifically, 4,4'-diphenylmethane diisocyanate, 4,4-diphenyldimethylmethane diisocyanate, 1,4-phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, hexamethylene diisocyanate, cyclohexane Diisocyanate, xylylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 1,3-phenylene diisocyanate, etc. are used, and organic monoisocyanates include isophorone isocyanate, phenyl isocyanate. Cyclohexyl isocyanate, butyl isocyanate, naphthyl isocyanate and the like are used. Moreover, the carbodiimide type compound which can be used for this invention is also available as commercial items, such as carbodilite V-02-L2 (brand name: Nisshinbo Co., Ltd. product).

  Specific examples of the oxazoline-based crosslinking agent include 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, 2-isopropenyl-5-ethyl-2-oxazoline, 2,2′-bis- (2-oxazoline), 2,2′-methylene-bis- (2 -Oxazoline), 2,2'-ethylene-bis- (2-oxazoline), 2,2'-trimethylene-bis- (2-oxazoline), 2,2'-tetramethylene-bis- (2-oxazoline), 2,2′-hexamethylene-bis- (2-oxazoline), 2,2′-octamethylene-bis- (2-oxazoline), 2,2′-ethylene-bis- (4 4'-dimethyl-2-oxazoline), 2,2'-p-phenylene-bis- (2-oxazoline), 2,2'-m-phenylene-bis- (2-oxazoline), 2,2'-m -Phenylene-bis- (4,4'-dimethyl-2-oxazoline), bis- (2-oxazolinylcyclohexane) sulfide, bis- (2-oxazolinyl norbornane) sulfide and the like. Furthermore, (co) polymers of these compounds can also be preferably used. Further, as a compound having an oxazoline group, Epocros K2010E, K2020E, K2030E, WS500, WS700 (all manufactured by Nippon Shokubai Chemical Co., Ltd.) and the like can be used.

  When the crosslinking agent in the present invention contains a crosslinking agent, it is preferably added in the range of 1 to 200% by mass, more preferably in the range of 5 to 100% by mass with respect to the total amount of the binder. . By making the addition amount 1% by mass or more, prevention of fine particle peeling becomes effective. On the other hand, when the addition amount is 200 mass or less, the surface shape tends to be further improved. Two or more types of crosslinking agents may be included, and when two or more types are included, the total amount is preferably within the above range.

<Matting agent>
As the matting agent, either organic or inorganic fine particles can be used. For example, polymer fine particles such as polystyrene, polymethyl methacrylate, silicone resin, and benzoguanamine resin, and inorganic fine particles such as silica, calcium carbonate, magnesium oxide, and magnesium carbonate can be used. Among these, polystyrene, polymethyl methacrylate, and silica are preferable from the viewpoint of the effect of improving the slipperiness and cost.

The average particle size of the matting agent is preferably 0.03 to 1 μm, more preferably 0.05 to 0.5 μm. By making the average particle size of the matting agent 0.03 μm or more, the effect of improving the slip property is effectively exhibited, and by making the average particle size 1 μm or less, it tends to be able to suppress the deterioration of display quality of the display device. is there. When the matting agent is contained, the addition amount of the matting agent varies depending on the average particle size, but is preferably 0.1 to 30 mg / m ² , more preferably 0.5 to 20 mg / m ² . . When the addition amount of the fine particles is 0.1 mg / m ² or more, the effect of improving the slip property is more effectively exhibited, and when the addition amount is 30 mg / m ² or less, the transparency is lowered and the display device is displayed. It is possible to more effectively suppress the deterioration of display quality. Two or more types of matting agents may be included, and when two or more types are included, the total amount is preferably within the above range.
The average particle size of the matting agent in the present invention is a value measured by the same method as the average particle size of the fine particles described above. Regarding the detailed description, since the fine particles are replaced with the matting agent in the above description, the detailed description is omitted here.

<Surfactant>
Examples of the surfactant include known anionic, nonionic, and cationic surfactants. The surfactant is described in, for example, “Surfactant Handbook” (Nishi Ichiro, Imai Junichiro, Sho Kasai edited by Sangyo Kasho Co., Ltd., 1960). Moreover, when it contains surfactant, it is preferable that it is 0.1-30 mg / m < ² > as addition amount of this surfactant, More preferably, it is 0.2-10 mg / m < ² >. When two or more types of surfactant are included, the total amount is preferably within the above range. It is possible to effectively suppress repellency by setting the addition amount of the surfactant to 0.1 mg / m ² or more. By setting the addition amount to 30 mg / m ² or less, the surface condition tends to be improved.

<Antistatic agent>
The type of the antistatic agent is not particularly limited. For example, an electron conductive polymer such as polyaniline and polypyrrole, an ion conductive polymer having a carboxyl group or a sulfonic acid group in the molecular chain, conductive fine particles, etc. Is mentioned. Among these, the conductive tin oxide fine particles described in JP-A-61-20033 can be preferably used from the viewpoints of conductivity and transparency. The addition amount of the antistatic agent is preferably added so that the surface resistivity of the easy adhesion layer measured in an atmosphere of 25 ° C. and 30% RH is 1 × 10 ⁵ Ω or more and 1 × 10 ¹³ Ω or less. The surface resistivity can be suppressed 1 × 10 and a ⁵ Omega or lower the amount of the antistatic agent tends to transparency improvement of the laminated film, by the following 1 × 10 ¹³ Omega, dust It tends to be more difficult to adhere.

<Slip agent>
It is preferable to contain an aliphatic wax in the first layer because the film surface can be lubricated. The blending amount in the case of blending the aliphatic aliphatic wax is preferably 0.5 to 30% by mass, more preferably 1% to 10% by mass. By making this content 0.5 mass% or more, the slipperiness of the laminated film tends to be improved. By setting it as 30 mass% or less, it exists in the tendency which the adhesiveness with respect to a polyester film, a hard-coat layer, an adhesive, etc. improves more.
Specific examples of the aliphatic wax include plant-based waxes such as carnauba wax, candelilla wax, rice wax, wood wax, jojoba oil, palm wax, rosin modified wax, cucumber wax, sugar cane wax, esparto wax, and bark wax. Animal waxes such as beeswax, lanolin, whale wax, ibota wax, shellac wax, mineral waxes such as montan wax, ozokerite, ceresin wax, petroleum waxes such as paraffin wax, microcrystalline wax, petrolactam, and fishertro push wax And synthetic hydrocarbon waxes such as polyethylene wax, oxidized polyethylene wax, polypropylene wax, and oxidized polypropylene wax. Among these, carnauba wax, paraffin wax, and polyethylene wax are particularly preferable because they are easy to adhere to hard coats and pressure-sensitive adhesives and have good lubricity. These are preferably used as water dispersions because they can reduce the environmental burden and are easy to handle.

  The easy adhesion layer may have a single-layer structure or a layer structure of two or more layers. For example, when the easy adhesion layer has a two-layer structure, the second layer is provided on the first layer. The second layer may be provided on the surface of the first layer, or may be provided on the surface of the first layer via another layer. In this case, the second layer may contain the same binder as the first layer, or may contain a different kind of binder. Depending on the layer structure to be laminated, it is preferable to include a different type of binder from the first layer. Thereby, the adhesiveness of functional layers, such as a polyester film and a hard coat, can be improved.

  Although there is no restriction | limiting in particular in the thickness of a 2nd layer, In order to implement | achieve easy adhesiveness more, it is preferable that it is 10-500 nm, and it is more preferable that it is 20-200 nm. By setting the thickness of the second layer to 10 nm or more, the adhesion with the upper layer (usually a hard coat layer) can be further improved, and by setting the thickness to 500 nm or less, the surface shape is improved. There is a tendency. Further, from the viewpoint of effective suppression of rainbow unevenness when a hard coat layer is provided as an upper layer, the thickness is more preferably 60 to 100 nm.

  Similar to the first layer, the second layer may contain fine particles and, if necessary, a crosslinking agent, a matting agent, a surfactant, an antistatic agent, a slipping agent, and the like.

  What laminated | stacked one or more layers of the polyester film and the easily bonding layer is used as a laminated polyester film. A release layer may be further formed on the surface of the easy adhesion layer of the laminated polyester film of the present invention. Since the easy-adhesion layer contains a pressure-sensitive adhesive, if it is exposed, it may stick to an unintended article or the easy-adhesion layer itself may deteriorate. For this reason, in order to physically and chemically protect the easy-adhesion layer, a release layer is provided on the surface of the easy-adhesion layer, and the easy-adhesion layer is exposed by peeling the release layer during use. And can be bonded to other members.

  Examples of the release layer include those in which a release agent layer such as silicone is applied to various plastic films to form a release agent layer, and a polypropylene film alone, which is used as a release sheet for ordinary pressure-sensitive adhesive sheets Can be used.

(Hard coat layer)
The laminated film of the present invention can be preferably used as a hard coat film in which a hard coat layer is provided on the surface of an easy adhesion layer. As shown in FIG. 2, the hard coat layer 5 is laminated so as to face the easy adhesion layer. That is, the hard coat layer 5 is laminated so as to be in contact with the easy-adhesion layer 3 to form the hard coat film 10.

  The hard coat layer is preferably composed mainly of a curable resin having high chemical resistance and scratch resistance. Examples of such a curable resin include an ionizing radiation curable resin, a thermosetting resin, and a thermoplastic resin. Preferably, the film forming operation is easy with respect to the laminated film and the pencil hardness is set to a desired value. It is an ionizing radiation curable resin that can be easily increased.

  As the ionizing radiation curable resin used for forming the hard coat layer, those having an acrylate functional group are preferable, and polyester acrylate or urethane acrylate is particularly preferable. The polyester acrylate is composed of an oligomer (meth) acrylate of a polyester-based polyol. The urethane acrylate is composed of an acrylated oligomer composed of a polyol compound and a diisocyanate compound. In addition, as a monomer constituting the acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2 ethylhexyl (meth) acrylate, methoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate And phenyl (meth) acrylate.

  In order to further increase the hardness of the hard coat layer, a polyfunctional monomer can be used in combination. Specific polyfunctional monomers include, for example, trimethylolpropane tri (meth) acrylate, hexanediol (meth) acrylate, tripropylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, pentaerythritol tri (meth) acrylate , Dipentaerythritol hexa (meth) acrylate, 1,6 hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, and the like.

  Polyester oligomers used to form the hard coat layer include adipic acid and glycol (ethylene glycol, polyethylene glycol, propylene glycol, butylene glycol, polybutylene glycol, etc.) and triol (glycerin, trimethylolpropane, etc.) sebacic acid and glycol Examples thereof include polyadipate triol which is a condensation product with triol and polysebacate polyol. Note that a part or all of the aliphatic dicarboxylic acid may be substituted with another organic acid. In this case, as the other organic acid, isophthalic acid, terephthalic acid, phthalic anhydride, or the like is preferable because high hardness is expressed in the hard coat layer.

  The polyurethane oligomer used for forming the hard coat layer can be obtained from the condensation product of polyisocyanate and polyol. Specific polyisocyanates include adducts of methylene bis (p-phenylene diisocyanate), hexamethylene diisocyanate / hexane triol, hexamethylene diisocyanate, tolylene diisocyanate, tolylene diisocyanate trimethylolpropane, 1,5 Examples include naphthylene diisocyanate, thiopropyl diisocyanate, ethylbenzene-2,4-diisocyanate, 2,4-tolylene diisocyanate dimer, hydrogenated xylylene diisocyanate, tris (4-phenyl isocyanate) thiophosphate, Specific polyols include polyether polyols such as polyoxytate and methylene glycol, polyadipate polyols, and polycarbonate polyols. What polyester polyols, such as copolymers of acrylic acid esters and hydroxyethyl methacrylate can be exemplified.

  Furthermore, when using an ultraviolet curable resin as the ionizing radiation curable resin, photopolymerization of acetophenones, benzophenones, mifilabenzoyl benzoate, α-amyloxime ester, or thioxanthone is started in these resins. It is preferable to use n-butylamine, triethylamine, tri-n-butylphosphine and the like as photosensitizers as a photosensitizer.

  Urethane acrylate is rich in elasticity and flexibility and excellent in workability (bendability), but has insufficient surface hardness and is difficult to obtain with a pencil hardness of 2H or more. On the other hand, the polyester acrylate can form a hard coat layer with extremely high hardness by selecting the constituent components of the polyester. Then, since it is easy to make high hardness and flexibility compatible, the hard-coat layer which mix | blended polyester acrylate 40-10 mass parts with respect to urethane acrylate 60-90 mass parts is preferable.

The hard coat layer may contain an ultraviolet absorber. As a result, UV degradation of the laminated film and the colorant (particularly dye-based) can be prevented, and visibility and explosion-proof properties can be maintained for a long time. The kind of ultraviolet absorber is not specified. The addition amount is preferably 0.1 to 10% by mass with respect to the resin forming the hard coat layer. By setting the content to 0.1% by mass or more, the effect of preventing ultraviolet light deterioration is sufficiently exhibited, and by setting the content to 10% by mass or less, it is possible to more effectively suppress a decrease in wear resistance and scratch resistance.
The addition method is preferably used by dispersing in a solvent.

Although the thickness of a hard-coat layer is not specifically limited, The range of 1-15 micrometers is preferable.
The refractive index of the hard coat layer in the invention is preferably from 1.50 to 2.10, more preferably from 1.60 to 2.00, and even more preferably from 1.70 to 1.95. The refractive index n _HC of the hard coat layer preferably satisfies n ₂ ≧ n _HC when the refractive index of the second layer is n ₂ .

A hard coat film can be made into a touch panel by laminating a transparent electrode layer. In general, ITO (indium tin oxide) is used for the transparent electrode layer, and the electrode pattern is formed by patterning an ITO conductive film. The hard coat layer and the transparent electrode layer may be laminated so as to be in contact with each other, or an adjustment layer such as an optical adjustment layer may be laminated between the hard coat layer and the transparent electrode. The optical adjustment layer is provided to adjust the difference in refractive index between the layers.
The refractive index of ITO is about 2.1, which is larger than the refractive index of 1.6 of the polyester film that is the support substrate. Therefore, since the reflection intensity due to external light is different between the place where ITO is present and the place where ITO is not present, the ITO pattern can be seen and display quality is remarkably deteriorated. This phenomenon is called ITO bone appearance.
However, when the refractive index of the hard coat layer is within the above range, the transparent electrode layer can be prevented from appearing when a transparent electrode layer or the like is laminated on the hard coat film to form a touch panel. Thereby, the number of adjustment layers, such as an optical adjustment layer which comprises the laminated | multilayer film for touchscreens, can be reduced.

  The hard coat film may be a laminated film having other constituent layers. Specific examples include an optical adjustment layer, a gas barrier layer, a transparent electrode layer such as an ITO electrode, a prism layer, an antireflection layer, and the like.

The hard coat film of the present invention can be preferably used for a liquid crystal display, a plasma display, an organic EL display, a CRT display, electronic paper, a touch panel, a PDP electromagnetic shielding film and the like. Moreover, it can use preferably also as a protective sheet for solar cells, or a film for window pasting. Especially, it is preferable that the hard coat film of this invention is used for the laminated film for touch panels. Regarding the touch panel, descriptions in JP-A-2002-48913 can be referred to.
Since the hard coat film of the present invention has high transparency, it is particularly preferably used for touch panel applications, and the hard coat film of the present invention may be a hard coat film for touch panels.

(Production method of polyester film, laminated polyester film and hard coat film)
Next, a method for producing the polyester film, laminated polyester film and hard coat film of the present invention will be described.

The method for producing a polyester film of the present invention includes a step of performing glow discharge treatment by setting the surface temperature of the polyester film to be equal to or higher than the Tg of the polyester film.
The method for producing a laminated polyester film of the present invention comprises a step of performing a glow discharge treatment with the surface temperature of the polyester film being equal to or higher than the Tg of the polyester film, and a step of laminating an easy adhesion layer on the surface of the polyester film subjected to the glow discharge treatment. Including.
The method for producing a hard coat film of the present invention includes a step of performing a glow discharge treatment with the surface temperature of the polyester film being equal to or higher than the Tg of the polyester film, and a step of laminating an easy adhesion layer on the surface of the polyester film subjected to the glow discharge treatment. And a step of laminating a hard coat layer on the surface of the easy-adhesion layer opposite to the surface on which the polyester film is laminated.

  Each process of the manufacturing method mentioned above may be performed after extending | stretching a polyester film to a uniaxial direction, may be performed after extending | stretching biaxially, and may be applied in the state which is not stretched at all.

  The surface temperature of the polyester film during the glow discharge treatment is more preferably Tg to 200 ° C of the polyester film, and more preferably Tg to 180 ° C.

  For details of heating of the polyester film, reference can be made to the corresponding description regarding the glow discharge treatment of the polyester film. Specific methods for raising the temperature of the film to be treated in vacuum include heating with an infrared heater, heating by contacting with a hot roll, and the like. Tables 2 and 3 show the heating temperature of the heating roll before the glow treatment.

  The step of performing glow discharge treatment on the surface of the polyester film heated to Tg or higher is a step of generating glow discharge on the surface of the polyester film heated to Tg or higher. By performing glow discharge treatment on the surface of the polyester film heated to Tg or more, it is possible to prevent oligomers from being deposited on the polyester film and to prevent the polyester film from being whitened. Furthermore, yellowing of the polyester film can be suppressed.

  The glow discharge treatment is preferably performed immediately after heating the polyester film. In the present invention, the glow discharge treatment is preferably performed when the surface temperature of the polyester film is Tg or higher. By performing the glow discharge treatment with the surface of the polyester film equal to or higher than Tg, the amount of change in the b value before and after the glow discharge treatment can be reduced. Moreover, it can also prevent that an oligomer precipitates from a polyester film. Therefore, the hard coat film obtained in the present invention has high transparency and is suitable for use as a touch panel.

  The step of laminating the easy adhesion layer is a step of laminating the easy adhesion layer on the surface of the polyester film that has been subjected to the glow discharge treatment. The easy-adhesion layer is usually formed on the surface of the polyester film by coating. There is no restriction | limiting in particular as an application | coating method, Well-known methods, such as bar coater application | coating and slide coater application | coating, can be used.

  When applying the easy-adhesion layer, a solvent (coating solvent) can be used. As the coating solvent, water, toluene, methyl alcohol, isopropyl alcohol, methyl ethyl ketone and the like, and aqueous and organic solvent based coating solvents such as a mixed system thereof can be used. Among these, the method using water as a coating solvent is preferable in view of cost and ease of production.

  An easy-adhesion layer is hardened by drying after applying in a layer form on a polyester film. In the case where the easy-adhesion layer has a two-layer structure, it is preferable that the second layer is coated and then dried to be effective.

The step of laminating the hard coat layer is a step of laminating the hard coat layer on the surface of the easy adhesion layer opposite to the surface on which the polyester film is laminated. The hard coat layer and the polyester film are laminated via an easy adhesion layer.
The hard coat layer can be formed, for example, by applying the hard coat layer composition to the surface of the easy adhesion layer. The hard coat layer composition is exemplified by a composition containing a curable resin. In this case, the solid content concentration of the hard coat layer composition is preferably 30 to 70% by mass, and more preferably 40 to 60% by mass.
As a method for applying the hard coat layer composition to the surface of the easy-adhesion layer, a conventionally known method can be appropriately selected according to the properties and application amount of the hard coat layer composition. Specific examples include a roll coating method, a gravure coating method, a bar coating method, and an extrusion coating method.
The hard coat layer is usually cured after the hard coat layer composition is applied in layers. As a curing method, a curing method according to the material of the hard coat layer composition can be employed. For example, in the case of an ionizing radiation curable resin, curing is performed by ionizing radiation irradiation.

On the hard coat layer, another constituent layer may be further laminated to form a touch panel. For example, an optical adjustment layer can be laminated on the hard component layer. A plurality of optical adjustment layers may be laminated. In this case, the optical adjustment layer preferably has a different refractive index.
A transparent electrode layer can be further laminated on the optical adjustment layer. The transparent electrode layer can be used as a touch panel electrode.
Each of the optical adjustment layer and the transparent electrode layer can be appropriately selected from conventional known methods.

  The features of the present invention will be described more specifically with reference to examples and comparative examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

  The evaluation criteria in the present invention are as follows.

(Evaluation of b value)
b was measured by a transmission method using a spectral color difference meter (SE-2000, Nippon Denshoku Industries Co., Ltd.).

(Non-crystallinity / crystallinity)
The peak ratio was measured and calculated by the ATR-IR method.

(Surface modification depth)
The modified depth from the surface was evaluated by a cross-sectional TEM.

(Evaluation of transparency)
Transparency was evaluated by measuring the total light transmittance and the amount of change in haze before and after heat treatment, and evaluating this result. The total light transmittance and haze were measured according to JIS-K-7105 using a haze meter (NDH-2000, Nippon Denshoku Industries Co., Ltd.).
For the amount of change in haze before and after heat treatment (unit:%), measure the haze before and after the heat treatment under the specified conditions (that is, without heat treatment) and after the heat treatment. When the haze after H1 and heat treatment was set to H2, it calculated | required by the type | formula of | H2-H1 | / H1 * 100.
The heat treatment in the haze measurement was performed by placing a sample sampled from the conductive film 10 in an oven set at an internal temperature of 150 ° C. and holding for 10 minutes. In addition, the haze measurement after heat processing was implemented after cooling the sample taken out from oven.

(Evaluation of oligomer precipitation)
Presence or absence of oligomer precipitation was evaluated as follows. The sample was heat-treated under the same conditions as the heat treatment in haze measurement, and after the sample taken out was cooled, it was observed whether or not the appearance was changed as compared with the sample before the heat treatment. Each evaluation standard is as follows.
A: When there is no change B: When it becomes slightly cloudy C: When cloudiness or white spots are confirmed

(Evaluation of wound after winding)
About 30 m was sampled from the roll after winding, and the state of the scratch was visually confirmed.
○: Almost no scratches that can be visually confirmed Δ: Occurrence of scratches that can be visually confirmed is confirmed, less than 10 per m ² ×: Scratches that can be visually confirmed are confirmed, 10 per 1 m ² More than

(Evaluation of adhesion of hard coat film and rainbow unevenness)
Using a single-edged razor, the surface of the sample to which the hard coat layer was applied was scratched by 6 scratches in the vertical and horizontal directions to form 25 squares. Next, a cellophane tape (trademark: No. 405 manufactured by Nichiban Co., Ltd., 24 mm width) is attached onto this, and then completely adhered by rubbing with poppy rubber from above, and then the tape is 90 degrees with respect to the hard coat layer. It peeled by pulling in the direction, and the following ranking was performed by obtaining the number of peeled squares to evaluate the adhesion between the hard coat layer and the easy adhesion layer. Evaluation ranks 3 to 5 are practically acceptable ranges.
5: No peeling occurs 4: The peeled squares are zero, but the scratch part is slightly peeled off.
3: The square which peeled was less than 1 square.
2: The square which peeled was 1 square or more and less than 5 squares.
1: The square which peeled was 5 squares or more.

(Evaluation of adhesion after wet heat aging)
Each polymer sheet was held for 500 hours under the environmental conditions of 80 ° C. and 10% RH and 65 ° C. and 95% RH, and then conditioned for 1 hour under the environment of 25 ° C. and 60% RH. The adhesion was evaluated by the method.

(Evaluation of rainbow unevenness (interference unevenness))
A sample coated with a hard coat layer was irradiated on a coated layer with diffused light from a fluorescent lamp through a milky white acrylic plate from a desk on which a black doskin cloth was laminated, and the reflected light generated was visually observed. And the rainbow-shaped interference nonuniformity observed at this time was judged by the following reference | standard, and this was evaluated as a coating surface shape. Moreover, in visual judgment, the blackening process was performed with respect to the sample as forced condition evaluation, and it adjusted so that the transmittance | permeability of 500 nm light might be set to 1% or less. As blackening treatment, magic ink (artline oil-based marker supplement ink KR-20 black, manufactured by shachihata Co., Ltd.) was applied to the surface of the sample opposite to the surface to be observed, and then dried. .
Rank A: Iridescent interference unevenness is not visually confirmed in both the sample after blackening and the untreated sample.
Rank B: Irregular interference unevenness is visually confirmed in the sample after the blackening treatment, but is not confirmed in the untreated sample.
Rank C: Rainbow-like interference unevenness is visually confirmed in both the blackened sample and the untreated sample.

(Evaluation of the number of adjustment layers)
In general, ITO (indium tin oxide) is used for the transparent electrode used in the liquid crystal display element, and the electrode pattern is formed by patterning the ITO conductive film. The refractive index of ITO is about 2.1, which is larger than that of PET, which is a supporting substrate, of about 1.6. Therefore, since the reflection intensity due to external light is different between the place where ITO is present and the place where ITO is not present, the ITO pattern can be seen and display quality is remarkably deteriorated. This phenomenon is called ITO bone appearance.
As one of the means for avoiding this ITO bone appearance, it is known to optimally adjust the refractive index and film thickness of ITO, the refractive index and film thickness of the insulating film and alignment film formed on the ITO, The optimum condition can be derived by theoretical calculation. Since the ITO bone appearance phenomenon can theoretically be treated as reflection of a multilayer film with different refractive indexes, the characteristics can be understood by calculating the reflection of a general multilayer film. Are almost identical.
In order to solve the bone appearance, it is an effective means to make the HC film according to the design of ITO, and an adjustment layer with ITO is required on the HC.
In order to bring the HC layer closer to ITO, the easy adhesion layer underneath is also required to have a high refractive index.
By inserting an intermediate refractive index layer having a refractive index intermediate between the refractive index of the ITO film (2.0 to 2.1) and the refractive index of HC and a film thickness of 50 nm to 100 nm, Optical interference conditions that reduce the color difference between the ITO electrode portion A and the portion B without the ITO electrode can be satisfied, and as a result, the bone appearance phenomenon of the ITO electrode can be reduced. Therefore, if the refractive index of HC is increased, the intermediate refractive index adjusting layer can be reduced.
If there are many adjustment layers, errors in the adjustment layer accumulate, and optical interference remains, making it difficult to eliminate the bone appearance phenomenon. In order to increase the refractive index of HC, it is necessary to increase the refractive index of easy adhesion.
Optical adjustment layer:
○: 1 to 2 layers Δ: 3 to 4 layers ×: 5 layers

(Evaluation of ITO bone appearance)
A transparent conductive film was placed on a black plate so that the surface on which the intermediate layer and ITO layer were laminated, and whether or not the pattern portion and non-pattern portion could be visually determined was evaluated according to the following criteria. .
A: Difficult to distinguish between a pattern part and a non-pattern part.
○: A pattern portion and a non-pattern portion can be slightly distinguished.
X: A pattern part and a non-pattern part can be distinguished clearly.

Example 1
<Creation of polyester film>
Polyethylene terephthalate (hereinafter referred to as PET) resin having an intrinsic viscosity of 0.66 (dl / g) obtained by polycondensation using Ge as a catalyst and a Tg temperature of 69 ° C. is dried to a moisture content of 50 ppm or less, and the heater temperature is set to 280 to It was set to 300 ° C. and melted in an extruder. The melted PET resin was discharged from a die part onto a chill roll electrostatically applied to obtain an amorphous base. The obtained amorphous base was stretched 3.3 times in the base traveling direction and then stretched 3.8 times in the width direction to obtain a PET film having a thickness of 188 μm. The refractive index was 1.65.

  While the PET film formed as described above was conveyed at a conveyance speed of 80 m / min, glow discharge treatment was performed on both surfaces under vacuum conditions. The surface temperature of the PET film before the glow discharge treatment was 110 ° C.

<Creation of easy adhesion layer>
The following formulation was used for the easy-adhesion layer coating solution.

In addition, the said prescription is adjusted so that the refractive index of the easily bonding layer after application | coating drying may be 1.66. An easy-adhesion layer coating solution was applied to the surface of the PET film subjected to the glow discharge treatment by a bar coating method so that the coating amount was 5.05 cm ³ / m ² . And this was dried at 170 degreeC for 2 minutes. A laminated film having an easy-adhesion layer applied on both sides of the PET film was obtained. In addition, the film thickness of the easy-adhesion layer was measured by observing the laminated film at a magnification of 200,000 using a transmission electron microscope (JEM2010 (manufactured by JEOL Ltd.)). The film thickness was 150 nm.

<Creation of hard coat film>
A hard coat film was prepared by providing a hard coat layer on the laminated films of the above Examples and Comparative Examples.
On both surfaces of the laminated film, an ultraviolet curable resin (made by DIC Corporation, Unidic 17-806, refractive index 1.66) was applied so that the film thickness was about 6 μm, and an application layer was provided. The coating layer was dried at 70 ° C. for 1 minute. Next, the dried coating layer was irradiated with ultraviolet rays using a high pressure mercury lamp to cure the resin, thereby forming a hard coat layer having a thickness of 3 μm. In addition, the irradiation amount of the ultraviolet-ray with respect to a coating layer was 1000 mJ / cm < ² >. The refractive index of the hard coat layer was 1.66.

  The hard coat film obtained in Example 1 had a b value of 1.22. In addition, oligomer precipitation was slight, and the transparency of the easy-adhesion layer was high. Further, the adhesion between the hard coat layer and the easy-adhesion layer was also good.

(Examples 2 to 7)
A hard coat film was prepared in the same manner as in Example 1 except that the surface temperature of the PET film before the glow discharge treatment was 150 ° C. and the glow discharge treatment conditions were changed to 4.0 to 50 KJ / m ² . . In addition, the refractive index of the easily bonding layer was 1.66.
The hard coat films obtained in Examples 2 to 8 had a b value in the range of 1.24 to 1.42. Moreover, there was no precipitation of an oligomer and the transparency of the easily bonding layer was high. Further, the adhesion between the hard coat layer and the easy-adhesion layer was also good. Moreover, in Examples 2-5, the rainbow nonuniformity was hardly confirmed. By setting the modification depth to 220 nm or less, a more preferred hard coat film can be obtained.

(Example 8)
A hard coat film was prepared in the same manner as in Examples 2 to 7 except that zirconium oxide was used as the fine particles of the easy adhesion layer. In addition, the refractive index of the easily bonding layer was 1.66.
The hard coat film obtained in Example 8 had a b value of 1.25. Moreover, there was no precipitation of an oligomer and the transparency of the easily bonding layer was high. Further, the adhesion between the hard coat layer and the easy-adhesion layer was also good.

Example 9
A hard coat film was prepared in the same manner as in Example 8 except that the binder of the easy adhesion layer was changed to a mixture of polyolefin and polyester. In addition, the refractive index of the easily bonding layer was 1.66.
The hard coat film obtained in Example 9 had a b value of 1.25. Moreover, there was no precipitation of an oligomer and the transparency of the easily bonding layer was high. Further, the adhesion between the hard coat layer and the easy-adhesion layer was also good.

(Example 10)
A hard coat film was prepared in the same manner as in Example 8 except that the binder of the easy adhesion layer was changed to polyolefin. In addition, the refractive index of the easily bonding layer was 1.66.
The hard coat film obtained in Example 10 had a b value of 1.25. Moreover, there was no precipitation of an oligomer and the transparency of the easily bonding layer was high. Further, the adhesion between the hard coat layer and the easy-adhesion layer was also good.

(Example 11)
A hard coat film was prepared in the same manner as in Example 8 except that the binder of the easy adhesion layer was changed to SBR. In addition, the refractive index of the easily bonding layer was 1.66.
The hard coat film obtained in Example 11 had a b value of 1.25. Moreover, there was no precipitation of an oligomer and the transparency of the easily bonding layer was high. Further, the adhesion between the hard coat layer and the easy-adhesion layer was also good.

(Example 12)
A hard coat film was prepared in the same manner as in Example 8 except that the thickness of the easy adhesion layer was 80 nm. In addition, the refractive index of the easily bonding layer was 1.75.
The hard coat film obtained in Example 12 had a b value of 1.25. Moreover, there was no precipitation of an oligomer and the transparency of the easily bonding layer was high. Further, the adhesion between the hard coat layer and the easy-adhesion layer was also good. In Example 12, since the refractive index of the hard coat layer could be increased to 1.84, the number of refractive index adjustment layers could be reduced. Furthermore, even when used for touch panel applications, there was no bone appearance of the ITO electrode. Example 12 can be particularly suitably used for touch panel applications.

(Example 13)
A hard coat film was prepared in the same manner as in Example 12 except that tin oxide was used as the fine particles of the easy adhesion layer. In addition, the refractive index of the easily bonding layer was 1.75.
The hard coat film obtained in Example 13 had a b value of 1.25. Moreover, there was no precipitation of an oligomer and the transparency of the easily bonding layer was high. Further, the adhesion between the hard coat layer and the easy-adhesion layer was also good. In Example 13, since the refractive index of the hard coat layer could be increased to 1.84, the number of refractive index adjustment layers could be reduced. Furthermore, even when used for touch panel applications, there was no bone appearance of the ITO electrode. Example 13 can be used particularly suitably for touch panel applications.

(Example 14)
In Example 14, two easy-adhesion layers were provided. The first layer of the easy adhesion layer was prepared in the same manner as in Example 13 except that the film thickness was 85 nm. The second layer of the easy adhesion layer was prepared in the same manner as in Example 1 except that the binder was polyolefin and the film thickness was 90 nm. The refractive index of the easy-adhesion layer was 1.59 for the first layer and 1.52 for the second layer.
The hard coat film obtained in Example 14 had a b value of 1.25. Moreover, there was no precipitation of an oligomer and the transparency of the easily bonding layer was high. Further, the adhesion between the hard coat layer and the easy-adhesion layer was also good.

(Example 15)
In Example 15, a hard coat film was prepared in the same manner as in Example 3 except that the film thickness of the polyester film was changed to 125 μm. In addition, the refractive index of the easily bonding layer was 1.66.
The hard coat film obtained in Example 15 had a b value of 0.85. Moreover, there was no precipitation of an oligomer and the transparency of the easily bonding layer was high. Further, the adhesion between the hard coat layer and the easy-adhesion layer was also good. In Example 15, rainbow unevenness was not confirmed.

(Example 16)
In Example 16, a hard coat film was prepared in the same manner as in Example 3 except that the film thickness of the polyester film was changed to 100 μm. In addition, the refractive index of the easily bonding layer was 1.66.
The hard coat film obtained in Example 16 had a b value of 0.75. Moreover, there was no precipitation of an oligomer and the transparency of the easily bonding layer was high. Further, the adhesion between the hard coat layer and the easy-adhesion layer was also good. In Example 16, rainbow unevenness was not confirmed.

(Comparative Example 1)
The configuration of the easy adhesion layer was the same as in Example 1, and the film thickness was 85 nm. In Comparative Example 1, the glow discharge treatment was not performed on the PET film. The refractive index of the easily bonding layer was 1.59.
In Comparative Example 1, since the glow discharge treatment was not performed at Tg or more, precipitation of the oligomer was confirmed, and the transparency of the easy adhesion layer was deteriorated. Moreover, the adhesiveness of a hard-coat layer and an easily bonding layer was bad, and the wound after winding also generate | occur | produced.

(Comparative Example 2)
An easy-adhesion layer was prepared in the same manner as in Comparative Example 1. In Comparative Example 2, the glow discharge treatment was not performed on the PET film. The refractive index of the easily bonding layer was 1.66.
In Comparative Example 2, since glow discharge treatment was not performed at Tg or higher, oligomer precipitation was confirmed, and the transparency of the easy-adhesion layer was deteriorated. Further, the adhesion between the hard coat layer and the easy-adhesion layer was very poor, and scratches after winding were also generated.

(Comparative Example 3)
An easy-adhesion layer was prepared in the same manner as in Comparative Example 1. The film thickness was 150 nm. In Comparative Example 3, the PET film was subjected to corona treatment. The surface temperature of the PET film before the corona treatment was 150 ° C. The refractive index of the easily bonding layer was 1.66.
In Comparative Example 3, since the corona treatment was performed instead of the glow discharge treatment, oligomer precipitation was slightly confirmed, and the transparency of the easy adhesion layer was deteriorated. Moreover, the adhesiveness of a hard-coat layer and an easily bonding layer was bad, and the wound after winding also generate | occur | produced.

(Comparative Examples 4 and 5)
An easy-adhesion layer was prepared in the same manner as in Comparative Example 3. In Comparative Examples 4 and 5, the PET film was subjected to glow discharge treatment, but the surface temperature of the PET film before glow discharge treatment was 0 ° C. In Comparative Examples 4 and 5 were the conditions of the glow discharge treatment, respectively ^{4.0KJ / m 2, 150KJ / m} 2. The refractive index of the easily bonding layer was 1.66.
In Comparative Examples 4 and 5, the glow discharge treatment was performed, but the treatment was performed at a temperature considerably lower than Tg. For this reason, precipitation of the oligomer was confirmed, and the transparency of the easy adhesion layer deteriorated. Moreover, the adhesiveness of a hard-coat layer and an easily bonding layer was bad, and the wound after winding also generate | occur | produced.

(Comparative Example 6)
An easy-adhesion layer was prepared in the same manner as in Comparative Example 3. In Comparative Example 6, the PET film was subjected to glow discharge treatment, but the surface temperature of the PET film before glow discharge treatment was 60 ° C. The refractive index of the easily bonding layer was 1.66.
In Comparative Example 6, the glow discharge treatment was performed, but the treatment was performed at a temperature lower than Tg. Oligomer precipitation was slightly confirmed, and the transparency of the easy-adhesion layer deteriorated. Moreover, the adhesiveness of a hard-coat layer and an easily bonding layer was bad, and the wound after winding also generate | occur | produced.

(Comparative Example 7)
An easy-adhesion layer was prepared in the same manner as in Comparative Example 3. In Comparative Example 7, the PET film was flame treated. The surface temperature of the PET film before the flame treatment was 150 ° C. The refractive index of the easily bonding layer was 1.66.
In Comparative Example 3, the flame treatment was performed at Tg or higher. Oligomer precipitation was suppressed, and adhesion between the hard coat layer and the easy-adhesion layer was improved. However, b value became large and yellowing was confirmed.

(Comparative Example 8)
Comparative Example 8 is Toyobo PET film TA010. The refractive index of the easily bonding layer was 1.59.
In Comparative Example 8, oligomers are precipitated and bone appearance occurs. Moreover, since the number of refractive index adjustment layers is increasing, it is not suitable for touch panel applications.

(Comparative Example 9)
Comparative Example 9 is Toyobo PET film A4300 and the like. The refractive index of the easily bonding layer was 1.66.
In Comparative Example 9, oligomers are precipitated and the transparency of the easy adhesion layer is also deteriorated. In addition, bone appearance is occurring. Moreover, since the number of refractive index adjustment layers is increasing, it is not suitable for touch panel applications.

  The evaluation results of each item described in Examples 1 to 15 are summarized in Table 2, and the evaluation results of each item described in Comparative Examples 1 to 9 are summarized in Table 3.

Furthermore, in typical examples among the examples and comparative examples described in Table 2 and Table 3, the b value when the film thickness of the polyester film was changed was measured. FIG. 3 summarizes the measurement results, and shows the relationship between the film thickness of the polyester film and the b value.
As shown by the triangular plot in FIG. 3, the b value of the polyester film according to the present invention is b = 0.006t + 0.55 or less. Further, the b value of the polyester film according to the present invention is preferably b = 0.006t + 0.38 or less, and more preferably b = 0.006t + 0.25 or less.

  According to the present invention, a laminated film in which both yellowing and whitening of a polyester film are suppressed can be obtained. Furthermore, according to the present invention, even when a hard coat layer or the like is laminated on the polyester film via an easy adhesion layer, the adhesion between the polyester film, the easy adhesion layer and the hard coat layer is improved. Can do. The hard coat film of the present invention is particularly suitably used for a touch panel and has high industrial applicability.

DESCRIPTION OF SYMBOLS 1 Polyester film 2 Surface modification layer 3 Easy adhesion layer 4 Laminated polyester film 5 Hard coat layer 10 Hard coat film

Claims (15)

A polyester film in which a surface modification layer having an amorphous degree (non-crystalline degree / crystalline degree) of 5% or more is formed,
The surface modified layer is formed as a surface layer of the polyester film, and the surface modified layer has a thickness from the surface of the polyester film to any depth within a range of 40 to 330 nm,
A polyester film having a b value of b = 0.006 t + 0.55 or less (where t represents the thickness of the polyester film).   The polyester film according to claim 1, wherein the surface modification layer has a thickness from the surface of the polyester film to any depth within a range of 50 to 220 nm.   3. The polyester film according to claim 1, wherein the surface modification layer has a non-crystallinity (non-crystallinity / crystallinity) of 5 to 8.3%.   The laminated polyester film characterized by facing the surface modification layer of the polyester film of any one of Claims 1-3, and the easily bonding layer is laminated | stacked.   A hard coat film, wherein a hard coat layer is laminated facing the easy-adhesion layer of the laminated polyester film according to claim 4.   The hard coat film according to claim 5, wherein a refractive index of the hard coat layer is 1.70 to 1.85.   A touch panel comprising the hard coat film according to claim 5 and a transparent electrode layer.   A method for producing a polyester film, comprising a step of performing glow discharge treatment on the surface of a polyester film heated to Tg or more (Tg means a glass transition temperature of the polyester film).   The method for producing a polyester film according to claim 8, wherein the surface of the polyester film is heated to Tg to 200 ° C.   10. The production of a polyester film according to claim 8, wherein in the step of performing the glow discharge treatment, a change amount (Δb) of the b value of the polyester film before and after the glow discharge treatment is set to 0.3 or less. Method.   It is a surface of the polyester film manufactured with the manufacturing method of the polyester film of any one of Claims 8-10, Comprising: It has the process of laminating | stacking an easily bonding layer on the surface which carried out the glow process, A method for producing a laminated polyester film.   A step of laminating a hard coat layer on the surface of the easy-adhesion layer of the laminated polyester film produced by the method for producing a laminated polyester film according to claim 11, opposite to the surface on which the polyester film is laminated. The manufacturing method of the hard coat film characterized by having.   The polyester film manufactured by the manufacturing method of any one of Claims 8-10.   A laminated polyester film produced by the production method according to claim 11.   A hard coat film produced by the production method according to claim 12.