JP5691322B2 - Method for producing biaxially oriented polyethylene terephthalate film for hard coat - Google Patents

Description

  The present invention relates to a hard-coated biaxially oriented polyethylene terephthalate (hereinafter abbreviated as PET) film suitable for touch panels, antireflection films, surface decorative films, protective films, and the like, and more particularly, plasma. The present invention relates to a biaxially oriented polyethylene terephthalate film used for an optical filter of a display panel, and further to a function integrated film in which a hard coat, a near infrared ray shielding, and an antireflection layer are laminated.

  The optical filter provided on the front of the plasma display panel (hereinafter referred to as PDP) prevents damage to the panel, shields electromagnetic waves that affect the human body and other electrical equipment leaking from the PDP, and shields near infrared rays that affect the remote control. Color tone correction by absorption of visible light near wavelength 590nm that reduces red purity due to emission of neon gas, reflection on the surface of external light such as sunlight and fluorescent lamps, and surface reflection prevention to prevent reflection, Functions such as scratch resistance and antifouling properties are required. A typical optical filter for PDP is to bond an electromagnetic wave shielding film and a near-infrared shielding / color tone correction film to a semi-tempered glass plate as a substrate with an adhesive, and an antireflection film to an opposite surface with an adhesive. The combination is mentioned. As an antireflection film, a hard coat layer is provided on a film substrate such as polyethylene terephthalate, and a thin film of a high refractive index layer and a low refractive index layer is further formed thereon as an antireflection layer to prevent reflection by light interference. A method has been carried out (see Patent Documents 1 and 2, etc.). In addition, as a near-infrared shielding film, a method of shielding a near-infrared ray by coating a film substrate such as polyethylene terephthalate with a composition in which a pigment that absorbs near-infrared rays is dispersed in a transparent polymer resin binder has been performed ( (See Patent Documents 3 and 4). Furthermore, color tone correction is also performed by mixing a dye that absorbs visible light near 590 nm, which lowers the red purity, with a near-infrared absorbing dye (see Patent Documents 5 and 6, etc.).

  Recently, as a means for reducing the cost of optical filters for PDPs, the number of parts has been reduced, and as one method, a near-infrared shielding layer is provided on the surface opposite to the antireflection layer of the antireflection film. Therefore, the anti-reflection (AR) and near-infrared (NIR) shielding on one film and the color tone correction function are integrated (see Patent Document 7 etc.) (hereinafter, the above film is integrated with the AR / NIR function) (Abbreviated as film). Furthermore, after laminating a hard coat layer and an antireflection layer, there is also a method of providing an adhesive layer on the other surface and pasting a near-infrared shielding film. Techniques for coating layers have also been established.

  In the case of this method, it is necessary to first provide a hard coat layer on the surface of the antireflection layer on the surface of the base film. Therefore, when the hard coat layer is dried and cured, curling occurs due to the difference in the thermal shrinkage of the base film. There is a problem that it is easy to do. When curling occurs in the hard coat film, problems such as poor workability, poor transportability, and uneven application of the near-infrared shielding layer occur. Therefore, a method for solving this problem is known by providing the heat shrinkage rate of the base film in a certain range. However, this technique is insufficient as an AR / NIR function integrated film. In the case of an AR / NIR function integrated film, it is necessary to laminate a near-infrared shielding layer on the opposite side of the hard coat layer, and a higher temperature drying treatment is performed there. This is because a problem that is likely to occur occurs. This problem is caused by the recent increase in screen size and resolution of PDPs, and the AR / NIR function integrated film also has a larger screen and higher definition, and it is necessary to improve the curl problem.

JP 2000-108238 A Japanese Patent Laid-Open No. 11-60637 Japanese Patent Laid-Open No. 11-326631 International Publication No. 97/38855 Pamphlet JP 58-153904 A JP 2000-275432 A JP 2002-138203 A JP 2008-36867 A JP 2008-246780 A JP 2009-149066 A

  The present invention solves such problems and has excellent processing suitability and flatness capable of suppressing curling when used as a base material for a hard coat film, and particularly suitable as an optical filter for a PDP, and particularly suitable for a hard coat biaxially oriented PET. Provide film.

That is, the present invention provides a hard coat layer having a drying step of 100 to 150 ° C. when providing a hard coat layer comprising at least an actinic radiation curable resin on one side of the film, and a near infrared ray absorbing ability on the other film side. The heat-shrinkage ratio Lt (%) in the film width direction when heat-treated at 140 ° C. for 30 minutes and 190 ° C. A method for producing a biaxially oriented polyethylene terephthalate film for hard coat, wherein the heat shrinkage ratio Ht (%) in the film width direction when heat-treated for 20 minutes satisfies the following formulas (1) to (3): the melt extrusion, after obtaining an unstretched polyethylene terephthalate film cooled and solidified, in the longitudinal direction and the width direction, Stretched 2.5 to 5.0 times in the longitudinal direction at 0 to 100 ° C., was stretched 3-5 times in the width direction at 70 to 150 ° C., heat to the film in the heat setting zone of 200 to 250 ° C. Fixing is performed, and 3 to 5 % of relaxation treatment is applied in the width direction in the range of 220 to 160 ° C. while cooling the film, and 0.5 to 1 in the width direction in the range of 180 to 100 ° C. while cooling the film. A method for producing a biaxially oriented polyethylene terephthalate film for hard coat, characterized by fine stretching at 0.0% and cooling the film to a glass transition temperature or lower.
(1) 0.0 ≦ Lt ≦ 0.6
(2) −0.2 ≦ Ht ≦ 0.8
(3) 0.0 ≦ (Lt−Ht) ≦ 0.5
Moreover, the manufacturing method of the biaxially-oriented polyethylene terephthalate film for hard-coats extended | stretched 2.5 to 5.0 time in the longitudinal direction at 70-100 degreeC, and extended 3-5 times in the width direction at 70-150 degreeC.
A method for producing a biaxially oriented polyethylene terephthalate film for hard coat having a light transmittance of 5% or less at a wavelength of 380 nm.

  In the present invention, curling caused by a difference in heat shrinkage when laminating a hard coat layer is small, and even when a near-infrared shielding layer is laminated on the surface opposite to the hard coat layer, curling can be suppressed. An axially oriented PET film and an AR / NIR function integrated film are provided.

Hereinafter, the biaxially oriented polyethylene terephthalate film for hard coat of the present invention and the function integrated film in which the hard coat and near infrared shielding are laminated will be described in more detail.

[Heat shrinkage of biaxially oriented PET film]
In the biaxially oriented PET film for hard coat of the present invention, the heat shrinkage ratio Lt (%) in the film width direction when heat-treated at 140 ° C. for 30 minutes satisfies the following formula (1): It must be 0 or more and 0.8 or less, more preferably 0.3 or more and 0.6 or less.
(1) 0.0 ≦ Lt ≦ 0.8.

  The biaxially oriented PET film of the present invention is used in such a manner that a hard coat layer is laminated on its surface, and when the hard coat layer is dried, it passes through a drying step of 100 to 150 ° C., and at that time, the hard coat layer The base film laminated with heat shrinks. Therefore, by setting the thermal shrinkage ratio Lt (%) of the biaxially oriented PET film (hereinafter sometimes referred to as “base film”) to be the base film within the above numerical range, It is possible to bring the rate close to the thermal contraction rate with the hard coat layer, and even when the hard coat layer is laminated, the occurrence of curling can be remarkably suppressed. On the other hand, when a hard coat layer is laminated on a biaxially oriented PET film whose Lt (%) is less than 0.0, the biaxially oriented PET film as a base film expands and the hard coat side is wound in the film width direction. It curls. Also, when a hard coat layer is laminated on a biaxially oriented PET film with Lt (%) exceeding 0.8, the base film shrinks more than the hard coat layer and curls so that the base film side is wound in the film width direction. Both are unfavorable because workability and transportability deteriorate, and further, quality problems such as deterioration of unevenness of interference with the hard coat and a functional layer for subsequent processing are not uniformly applied.

  Furthermore, the biaxially oriented PET film of the present invention may be laminated with a functional layer such as a vapor deposition layer, a printing layer, or a near infrared shielding layer on the opposite side of the surface on which the hard coat layer is laminated, For example, in the case of a near-infrared shielding layer, a color change occurs when a small amount of solvent remains, and therefore, it passes through a high-temperature drying process at 180 to 200 ° C. (particularly 190 ° C. in many cases). Therefore, the heat shrinkage ratio Ht (%) in the film width direction of the biaxially oriented PET film when heat-treated at 190 ° C. for 20 minutes needs to be equal to or less than Lt (%). When Ht (%) exceeds Lt (%), the base film is thermally shrunk in the high-temperature drying step, so that the hard coat side is curled so as to warp outward, resulting in quality problems such as wrinkles and poor flatness. Further, even if Ht (%) is less than or equal to Lt (%), if the difference between Ht (%) and Lt (%) exceeds 0.5, in the high temperature drying step, the film will thermally expand, It curls so that the near-infrared shielding layer side warps outward, which causes quality problems such as wrinkles and poor flatness. That is, in the present invention, it is preferable to satisfy the following expression (3).

• 0.0 ≦ (Lt−Ht) ≦ 0.5.
More preferably, the value of (Lt−Ht) is 0.1 or more and 0.3 or less.

Next, from the above formulas (1) and (3), the numerical range that Ht (%) can take is −0.5 or more and 0.8 or less, but when Ht (%) is less than −0.2. The flatness of the substrate film is deteriorated, which is not preferable. Although there is a method of annealing, it is not preferable from the viewpoint of cost. Therefore, in the present invention, it is necessary to satisfy the following expression (2). That is, Ht (%) needs to be −0.2 or more and 0.8 or less, and more preferably 0.0 or more and 0.5 or less.
(2) −0.2 ≦ Ht ≦ 0.8.

  Subsequently, the thermal shrinkage rate in the film longitudinal direction of the biaxially oriented PET film will be described. In the longitudinal direction of the biaxially oriented PET film, tension is always applied from unwinding to winding in both the laminating of the hard coat layer and the laminating of the functional layer, and there are problems such as curling and wrinkling. Is hard to happen. However, in order to reduce curl and wrinkles to the utmost limit, the heat shrinkage (Lm) in the longitudinal direction when heat-treated at 140 ° C. for 30 minutes is 0.0% to 2.0%, and further 0.5 to 1. Preferably, the heat shrinkage rate (Hm) in the longitudinal direction when heat-treated at 190 ° C. for 20 minutes is 0.0% to 4.0%, more preferably 2.0 to 3.0%. It is preferable.

In a normal biaxially oriented PET film, by cooling from a high temperature state, as the thermal expansion in the high temperature state is cooled, it shrinks reversibly, so that strain is accumulated and a glass transition temperature (hereinafter referred to as a glass transition temperature). Is abbreviated as Tg.) To 255 ° C., heat shrinkability is added. Therefore, the 190 ° C. heat shrinkage rate is larger than the 140 ° C. heat shrinkage rate, and the higher the heating temperature in the high-order processing, the more the heat shrinkage rate tends to increase, and the above equation (2) is satisfied. Have difficulty. In the present invention, in order to control the heat shrinkability, for example, after heat fixing in the tenter, a relaxation treatment is performed so as to absorb the reversible shrinkage accompanying the cooling, and then a method of fine stretching in the cooling step is used. Thus, the above expressions (1) to (3) can be satisfied. An example of the method will be described below, but is not limited thereto. The biaxially stretched PET film has a heat setting temperature of 200 to 250 ° C., preferably 210 to 245 ° C., more preferably 220 to 240 ° C. Heat fix for 5-15 seconds. Subsequently, while the film is cooled from the heat setting temperature, a relaxation treatment is performed in the width direction with a relaxation rate of 1 to 12%, more preferably 2% to 10%, and still more preferably 3% to 8%. Moreover, the temperature for performing relaxation is preferably in the range of 220 ° C to 160 ° C. Here, the relaxation process refers to a process of narrowing the film width, for example, by narrowing the width of the clip. The relaxation rate is the rate at which the film shrinks in the width direction, where Li is the film width immediately before starting the relaxation process in the width direction, and Lf is the film width immediately after finishing the relaxation process in the width direction. Is represented by the following formula.
Width direction relaxation rate (%) = (Li−Lf) / Li × 100.

It is preferable to finely stretch the film in the width direction in the temperature range described below while continuing to cool the film. The ratio of fine stretching in the width direction (fine stretching ratio) is preferably 0.05% to 3.0%, more preferably 0.1% to 2.0%, still more preferably 0.3% to 1.5%. Moreover, the temperature which implements a micro extending | stretching process has the preferable inside of the range of 180 to 100 degreeC, More preferably, it is 160 to 120 degreeC. By carrying out this fine stretching step, it is possible to set the widthwise thermal shrinkage rates Ht and Lt at desired temperatures within a desired range. Here, the fine stretching ratio is expressed by the following equation when Bi is the film width before starting the fine stretching in the width direction, and Bf is the film width immediately after the fine stretching in the width direction is finished. It is what
Fine stretching ratio in width direction (%) = (Bf−Bi) / Bi × 100.

Thereafter, the film is cooled to the glass transition temperature or lower and then taken out from the tenter to obtain the biaxially oriented PET film of the present invention.
[Polyester constituting biaxially oriented PET film]
The resin of the base film (S layer) constituting the biaxially oriented PET film of the present invention requires that 80 mol% or more of the repeating structural units is ethylene terephthalate. In the present invention, the resin is preferably used from the balance of transparency, heat resistance, and cost. Other polyester copolymer components include diol components such as diethylene glycol, propylene glycol, neopentyl glycol, polyethylene glycol, p-xylene glycol, 1,4-cyclohexanedimethanol, or adipic acid, sebacic acid, phthalic acid, isophthalic acid And dicarboxylic acid components such as 5-sodium sulfoisophthalic acid and 2,6-naphthalenedicarboxylic acid, polyfunctional dicarboxylic acids such as trimellitic acid and pyromellitic acid, and p-hydroxyethoxybenzoic acid. In addition, one or more of an alkali metal salt derivative of a sulfonic acid that is not reactive with the polyester or a polyalkylene glycol or an aliphatic polyester that is insoluble in the polyester may be added to the polyester so as not to exceed 5%. You may superpose | polymerize thru | or blend.

  Fine particles may be added to the biaxially oriented PET film of the present invention, but the addition of the fine particles often reduces the properties relating to transparency such as light transmittance and haze. For this reason, when added, those having a particle diameter as small as possible, preferably having a particle diameter of about ¼ or less of the visible light wavelength at which scattering is difficult to occur, and the addition amount is also preferably a trace amount.

  Further, the biaxially oriented PET film may be a laminated structure obtained by coextrusion of two or more layers. As the laminated structure, for example, a composite film having an inner layer portion and a surface layer portion, which is substantially free of particles in the inner layer portion, and provided with a layer containing particles in the surface layer portion. The inner layer portion and the surface layer portion may be chemically different polymers or the same type of polymers. In the display application which is the main purpose of the present invention, it is preferable in terms of optical properties such as transparency that the substrate film does not contain particles.

  The PET film of the present invention preferably has a light transmittance of 5% or less at a wavelength of 380 nm, preferably 3% or less. By using the PET film of the present invention having such properties as a display member (for example, LCD, electronic paper, EL display, projection television member), particularly a plasma display member, other materials and other compounds constituting the display can be obtained. Can be protected from ultraviolet rays.

  In order to set the light transmittance of the PET film at a wavelength of 380 nm to 5% or less, it is preferable to contain an ultraviolet absorber in the PET film. Preferred examples of the ultraviolet absorber include salicylic acid compounds, benzophenone compounds, benzotriazole compounds, cyanoacrylate compounds, benzoxazinone compounds, cyclic imino ester compounds, and the like. Of these, benzoxazinone compounds are most preferred from the viewpoints of UV-cutting property and color tone. These compounds can be used alone or in combination of two or more. In addition, stabilizers such as H A L S and antioxidant can be used in combination, and it is particularly preferable to use a phosphorus-based antioxidant in combination.

  Examples of the benzotriazole-based compound include 2- (2H-benzotriazol-2-yl) -4,6-bis (1-methyl-1-phenylethyl) phenol and 2- (2H-benzotriazole-2). -Yl) -4- (1,1,3,3-tetramethylbutyl) phenol, 2- (2H-benzotriazol-2-yl) -4-methylphenol, 2- (2H-benzotriazole-2-) Yl) -4,6-di-t-butylphenol, 2- (2H-benzotriazol-2-yl) -4,6-di-t-amylphenol, 2- (2H-benzotriazol-2-yl) -4-t-butylphenol, 2- (2'-hydroxy-3'-t-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy- ', It can be exemplified 5'-di -t- butyl-phenyl) -5-chloro-benzotriazole, or the like.

  Examples of the benzophenone compounds include 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2′-dihydroxy-4,4′-dimethoxybenzophenone, 2,2 ′, 4,4 ′. -Tetrahydroxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid and the like can be mentioned.

  Examples of the benzoxazinone compounds include 2-p-nitrophenyl-3,1-benzoxazin-4-one, 2- (p-benzoylphenyl) -3,1-benzoxazin-4-one, 2- ( 2-naphthyl) -3,1-benzoxazin-4-one, 2,2'-p-phenylenebis (3,1-benzoxazin-4-one), 2,2 '-(2,6-naphthylene) Bis (3,1-benzoxazin-4-one) and the like can be exemplified.

  The film thickness of the biaxially oriented PET film of the present invention is not particularly limited and is appropriately selected depending on the application, but is usually 10 to 500 μm, preferably 20 to 300 μm.

In the present invention, it is preferable to provide a coating layer on the surface of the base film (S layer) in order to provide additional functions such as adhesion between the PET film and a layer applied in higher-order processing and low interference unevenness. The coating layer may be provided on one side or both sides. In particular, when a hard coat layer is provided on one side and a functional layer is provided on the opposite side as in the present invention, it is preferable to provide different layers on both sides.
The easy-adhesion layer is not limited to the following. For example, as a component constituting the easy-adhesion layer, when a polyester resin is used, the easy-adhesion layer has an ester bond in the main chain or side chain. It is obtained by polycondensation from acid and glycol. Here, as the dicarboxylic acid component, aromatic, aliphatic, and alicyclic dicarboxylic acids and trivalent or higher polyvalent carboxylic acids can be used. As aromatic dicarboxylic acids, terephthalic acid, isophthalic acid, orthophthalic acid, phthalic acid, 2,5-dimethylterephthalic acid, 1,4-naphthalenedicarboxylic acid, biphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,2 -Bisphenoxyethane-p, p'-dicarboxylic acid, phenylindanedicarboxylic acid, etc. can be used. These aromatic dicarboxylic acids are preferably used in an amount of 30 mol% or more, more preferably 35 mol% or more, and most preferably 40 mol% or more of the total dicarboxylic acid component in terms of the strength and heat resistance of the easy-adhesion layer. Good. Aliphatic and alicyclic dicarboxylic acids include succinic acid, adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, dimer acid, 1,3-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1, 4-Cyclohexanedicarboxylic acid and the like, and ester-forming derivatives thereof can be used. Examples of the glycol component constituting the polyester resin include ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1, 5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 2,4-dimethyl-2-ethylhexane -1,3-diol, neopentyl glycol, 2-ethyl-2-butyl-1,3-propanediol, 2-ethyl-2-isobutyl-1,3-propanediol, 3-methyl-1,5-pentane Diol, 2,2,4-trimethyl-1,6-hexanedio 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, 4,4'-thio Diphenol, bisphenol A, 4,4′-methylenediphenol, 4,4 ′-(2-norbornylidene) diphenol, 4,4′-dihydroxybiphenol, o-, m-, and p-dihydroxybenzene, 4, 4′-isopropylidenephenol, 4,4′-isopropylidenebindiol, cyclopentane-1,2-diol, cyclohexane-1,2-diol, cyclohexane-1,4-diol, and the like can be used. In the case of using a coating liquid containing a polyester resin as a water-based resin as a raw material for the easy-adhesion layer, a compound containing a sulfonate group or a carboxylate base is used to facilitate water-solubilization or water-dispersion of the polyester resin. It is preferable to copolymerize the compound containing to polyester. Here, examples of the compound containing a sulfonate group include sulfoterephthalic acid, 5-sulfoisophthalic acid, 4-sulfoisophthalic acid, 4-sulfonaphthalene-2,7-dicarboxylic acid, sulfo-p-xylylene glycol, 2-sulfo-1,4-bis (hydroxyethoxy) benzene and the like, or alkali metal salts, alkaline earth metal salts, and ammonium salts thereof can be used, but are not limited thereto. Examples of the compound containing a carboxylate group include trimellitic acid, trimellitic anhydride, pyromellitic acid, pyromellitic anhydride, 4-methylcyclohexene-1,2,3-tricarboxylic acid, trimesic acid, 1, 2,3,4-butanetetracarboxylic acid, 1,2,3,4-pentanetetracarboxylic acid, 3,3 ′, 4,4′-benzophenonetetracarboxylic acid, 5- (2,5-dioxotetrahydrofuran Furyl) -3-methyl-3-cyclohexene-1,2-dicarboxylic acid, 5- (2,5-dioxotetrahydrofurfuryl) -3-cyclohexene-1,2-dicarboxylic acid, cyclopentanetetracarboxylic acid, 2 , 3,6,7-Naphthalenetetracarboxylic acid, 1,2,5,6-naphthalenetetracarboxylic acid, ethylene glycol bistrimellite 2,2 ′, 3,3′-diphenyltetracarboxylic acid, thiophene-2,3,4,5-tetracarboxylic acid, ethylenetetracarboxylic acid, etc., or alkali metal salts, alkaline earth metal salts thereof, Although an ammonium salt can be used, it is not limited to these.

  As the polyester resin that can be used for the easy-adhesion layer, a modified polyester copolymer such as a block copolymer modified with acrylic, urethane, epoxy, or the like, a graft copolymer, or the like can also be used. As a more preferable polyester resin that can be used for the easy adhesion layer, one or more of terephthalic acid, isophthalic acid, sebacic acid, and 5-sodium sulfoisophthalic acid are used as the dicarboxylic acid component, and ethylene glycol as the glycol component. A copolymer using one or more selected from diethylene glycol, 1,4-butanediol, and neopentyl glycol. Here, when water resistance is required, a (co) polymer containing terephthalic acid as the dicarboxylic acid component and ethylene glycol as the glycol component is preferably used.

When an acrylic resin is used as a constituent component of the easy adhesion layer, examples of the monomer component constituting the acrylic resin include alkyl acrylate, alkyl methacrylate (the alkyl group is a methyl group, an ethyl group, an n-propyl group, an isopropyl group). N-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group, lauryl group, stearyl group, cyclohexyl group, phenyl group, benzyl group, phenylethyl group), 2-hydroxyethyl acrylate, 2-hydroxyethyl Hydroxyl group-containing monomers such as methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, acrylamide, methacrylamide, N-methyl acrylamide, N-methyl methacrylamide, N-methylol acrylamide Amide group-containing monomers such as N-methylol methacrylamide, N, N-dimethylol acrylamide, N-methoxymethyl acrylamide, N-methoxymethyl methacrylamide, N-phenyl acrylamide, N, N-diethylaminoethyl acrylate, N, N -Amino group-containing monomers such as diethylaminoethyl methacrylate, epoxy group-containing monomers such as glycidyl acrylate and glycidyl methacrylate, carboxyl groups such as acrylic acid, methacrylic acid and salts thereof (lithium salt, sodium salt, potassium salt, etc.) or salts thereof The monomer etc. which contain can be used, These are (co) polymerized using 1 type (s) or 2 or more types. Furthermore, other types of monomers other than those described above can be used in combination. Although it does not specifically limit as another kind of monomer which can be used here, For example, epoxy group containing monomers, such as allyl glycidyl ether, styrene sulfonic acid, vinyl sulfonic acid, and their salts (lithium salt, sodium salt, potassium salt, ammonium salt) Monomers containing sulfonic acid groups or salts thereof, such as crotonic acid, itaconic acid, maleic acid, fumaric acid and their salts (lithium salts, sodium salts, potassium salts, ammonium salts, etc.) or the like Monomers containing salts, monomers containing acid anhydrides such as maleic anhydride and itaconic anhydride, vinyl isocyanate, allyl isocyanate, styrene, vinyl methyl ether, vinyl ethyl ether, vinyl trisalkoxysilane, alkyl malein Monoesters, alkyl fumaric acid monoester, acrylonitrile, methacrylonitrile, alkyl itaconic acid monoester, vinylidene chloride, vinyl acetate, etc. can be used vinyl chloride. Moreover, as an acrylic resin which can be used for an easily bonding layer, a modified acrylic copolymer, for example, a block copolymer modified with polyester, urethane, epoxy, etc., a graft copolymer, etc. can also be included. Although the glass transition point (Tg) of the acrylic resin used for this easily bonding layer is not specifically limited, Preferably it is 0-90 degreeC, More preferably, it is 10-80 degreeC. When an acrylic resin having a low Tg is used, the heat-resistant adhesion tends to be inferior, and conversely, when it is too high, the film-forming property may be inferior. The molecular weight of the acrylic resin is preferably 100,000 or more, more preferably 300,000 or more from the viewpoint of adhesiveness.

  The more preferable acrylic resin used for the easy adhesion layer is selected from methyl methacrylate, ethyl acrylate, n-butyl acrylate, 2-hydroxyethyl acrylate, acrylamide, N-methylol acrylamide, glycidyl methacrylate, and acrylic acid (co-). A polymer etc. can be mentioned. A water-based acrylic resin in which an acrylic resin is dissolved, emulsified or suspended in water is preferably used as a raw material for the easy-adhesion layer from the viewpoint of environmental pollution prevention and explosion-proof properties during coating. Such an aqueous acrylic resin uses a copolymer having a monomer having a hydrophilic group (such as acrylic acid, methacrylic acid, acrylamide, vinyl sulfonic acid, and a salt thereof) and the above monomers, and a reactive emulsifier or a surfactant. It can be prepared by methods such as emulsion polymerization, suspension polymerization, soap-free polymerization.

  When a urethane resin is used as a constituent component of the easy-adhesion layer, the urethane-based composition 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 is mentioned.

  By appropriately selecting an easy-adhesion layer in accordance with the characteristics of high-order processing, it is possible to impart functions such as adhesion and interference unevenness. In particular, in terms of interference unevenness, the easy-adhesion layer between the layer applied in the high-order processing and the base film has an intermediate between the refractive index of the layer applied in the high-order processing and the refractive index of the base film. It is preferable to select a polyester resin or a combination of an acrylic resin and a polyester resin.

  Further, by using one or more cross-linking agents selected from the group consisting of melamine-based cross-linking agents, oxazoline-based cross-linking agents, and carbodiimide-based cross-linking agents as the cross-linking agent in the easy-adhesion layer, the adhesive property can be improved. Since the improvement of wet heat resistance due to the progress of the self-crosslinking reaction is preferable. Moreover, content of crosslinking agents, such as a melamine type | system | group, an oxazoline type | system | group, and a carbodiimide type, is not specifically limited, You may use 2 or more types of crosslinking agents.

  The melamine-based crosslinking agent is not particularly limited, but melamine, a methylolated melamine derivative obtained by condensing melamine and formaldehyde, a compound partially or completely etherified by reacting methylolated melamine with a lower alcohol, and these A mixture or the like can be used. The melamine-based crosslinking agent may be a monomer, a condensate composed of a dimer or higher polymer, or a mixture thereof. As the lower alcohol used for etherification, methyl alcohol, ethyl alcohol, isopropyl alcohol, n-butanol, isobutanol and the like can be used. The functional group has an imino group, a methylol group, or an alkoxymethyl group such as a methoxymethyl group or a butoxymethyl group in one molecule, and an imino group type methylated melamine resin, a methylol group type melamine resin, or a methylol group type. Examples include methylated melamine resins and fully alkyl type methylated melamine resins. Of these, methylolated melamine resins are most preferred. Further, an acidic catalyst such as p-toluenesulfonic acid may be used in order to accelerate the thermal curing of the melamine-based crosslinking agent.

  In the oxazoline-based cross-linking agent, the at least one other monomer used for the monomer containing the oxazoline group is not particularly limited as long as it is a monomer copolymerizable with the monomer containing the oxazoline group. Acrylates or methacrylates such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, acrylate-2-ethylhexyl, methacrylate-2-ethylhexyl, etc. Unsaturated carboxylic acids such as acid, methacrylic acid, itaconic acid and maleic acid, unsaturated nitriles such as acrylonitrile and methacrylonitrile, acrylamide, methacrylamide, N-methylolacrylamide, N-methylol methacrylate Contains unsaturated amides such as amides, vinyl esters such as vinyl acetate and vinyl propionate, vinyl ethers such as methyl vinyl ether and ethyl vinyl ether, olefins such as ethylene and propylene, vinyl chloride, vinylidene chloride and vinyl fluoride. Halogen- [alpha], [beta] -unsaturated monomers, [alpha], [beta] -unsaturated aromatic monomers such as styrene and [alpha] -methylstyrene can be used, and these should be used alone or in a mixture of two or more. You can also.

Further, the present carbodiimide-based crosslinking agent is particularly limited as long as the compound has one or two or more cyanamide groups in the molecule as a functional group, or a carbodiimide group as a functional group. is not. Specific examples of such carbodiimide compounds include dicyclohexylmethane carbodiimide, dicyclohexyl carbodiimide, tetramethylxylylene carbodiimide, urea-modified carbodiimide, and the like, and these may be used alone or as a mixture of two or more. .
Furthermore, it is more preferable to incorporate fine particles in the easy-adhesion layer, since the slipperiness and blocking resistance are improved. The fine particles to be included are not particularly limited, but inorganic particles such as colloidal silica, titanium oxide, aluminum oxide, zirconium oxide, calcium carbonate, carbon black, zeolite particles, acrylic particles, silicone particles, polyimide particles, “Teflon” (registered) (Trademark) particles, crosslinked polyester particles, crosslinked polystyrene particles, crosslinked polymer particles, core-shell particles, and the like, and any of these particles may be used or a plurality of types may be used in combination.

  The number average primary particle size of these particles is preferably in the range of 0.01 to 0.4 μm. Here, the average primary particle size is an average of the particle sizes of primary particles defined as particles generated by growth of a single crystal nucleus in JIS-H7008 (2002). The particle diameter of the primary particles (hereinafter referred to as the primary particle diameter) is the average value of the major axis and the minor axis. For the measurement of such average primary particle size, according to JIS-H7804 (2005), the sample was observed at a magnification of 50,000 times using a scanning electron microscope (SEM), and the major axis of each primary particle was used using a photograph. The average primary particle diameter can be determined from the number average value obtained by measuring the primary diameter by measuring the average diameter and determining the primary particle diameter by average. If the average primary particle size of the particles is less than 0.01 μm, the particles may aggregate and deteriorate the haze of the easy-adhesion layer. In addition, it is difficult to obtain an effect of blocking resistance and particles may fall off depending on the thickness of the easy adhesion layer. The average primary particle size of the particles is more preferably in the range of 20 to 300 nm, still more preferably in the range of 20 to 200 nm. The particles may be monodispersed particles or aggregated particles in which a plurality of particles are aggregated. In some cases, a plurality of types of particles having different average primary particle sizes may be used in combination. The addition amount of the particles should be appropriately adjusted and designed according to the thickness of the easy-adhesion layer, the resin composition, the average primary particle size, the required slipperiness and usage, etc. In the range of 0.05 to 8 parts by weight, more preferably in the range of 0.1 to 5 parts by weight.

  Furthermore, the easy-adhesion layer of the biaxially oriented PET film of the present invention has various additives such as antioxidants, heat stabilizers, weather stabilizers, ultraviolet absorbers, organic absorbers within the range that does not impair the effects of the present invention. Lubricants, pigments, dyes, organic or inorganic fine particles, fillers, antistatic agents, nucleating agents, and the like may be incorporated, but are not limited thereto.

  Moreover, as a method of laminating the easy-adhesion layer on the base film (S layer), a method of coating (coating) a coating agent constituting the easy-adhesion layer on each surface of the S layer and laminating is preferable. As such a coating method, coating is performed in a process separate from the manufacturing process of the S layer, that is, a so-called off-line coating method, and laminated PET in which coating is performed during the manufacturing process of the S layer and an easy adhesion layer is stacked on the S layer. There is a so-called in-line coating method for obtaining a film at once. Further, for example, a method of laminating one side by an in-line coating method and then laminating the other side by an off-line coating method may be used. In the present invention, it is preferable to adopt an in-line coating method from the viewpoint of cost and uniformity of coating thickness, and the solvent of the coating liquid used in that case is most preferably an aqueous system from the viewpoint of environmental pollution and explosion-proof properties. preferable.

  In addition, the application method of the water-based coating agent may be, for example, a reverse coating method, a spray coating method, a bar coating method, a gravure coating method, a rod coating method, or a die coating method, but is not limited thereto.

  Furthermore, before applying the water-based coating agent, the surface of the S layer as the base film may be subjected to a corona discharge treatment or the like, and the wetting tension of the surface is preferably 47 mN / m or more, more preferably 50 mN / m. The above is preferable. This is because the adhesion between the S layer and the easy-adhesion layer is improved and the coating property is also improved.

[Method for producing biaxially oriented PET film]
Although shown below as a manufacturing method of the biaxially oriented PET film of this invention, the manufacturing method of the film of this invention is not limited to this.

After the PET pellets are vacuum dried, they are supplied to an extruder, melted at 260 to 300 ° C., extruded into a sheet form from a T-shaped die, and applied to a mirror surface casting drum having a surface temperature of 10 to 60 ° C. using an electrostatic application casting method. It is wound and cooled and solidified to produce an unstretched (unoriented) PET film. This unstretched film is stretched 2.5 to 5.0 times in the longitudinal direction between rolls heated to 70 to 100 ° C. to obtain a uniaxially stretched (uniaxially oriented) film. In addition, even if one side or both sides of the uniaxially stretched (uniaxially oriented) film is subjected to corona discharge treatment in the air, the wetting tension of the film surface is set to 47 mN / m or more, and the above-mentioned easy adhesion layer is provided on the treated surface. good. Subsequently, the uniaxially stretched (uniaxially oriented) film is held with a clip and guided to a tenter. In the tenter, first, the film is preheated in a preheating zone having a preheating temperature of 70 to 150 ° C. Subsequently, the film is continuously stretched 3 to 5 times in the width direction in a stretching zone having a stretching temperature of 70 to 150 ° C. Subsequently, the film is heat-set in a heat setting zone having a heat setting temperature of 200 to 250 ° C. After heat setting, the film is cooled and subjected to a relaxation treatment with a relaxation rate of 2 to 12% in the width direction in the temperature range of 220 to 160 ° C. Subsequently, while the film is cooled, the film is stretched slightly in the width direction in the temperature range of 180 ° C. to 100 ° C. with a magnification (fine stretching ratio) of 0.05% to 3.0%. Thereafter, the film is cooled to below the glass transition temperature and taken out of the tenter to obtain the biaxially oriented PET film of the present invention.
[Laminated film for optics]
Next, an optical laminated film in which a hard coat layer is provided on the biaxially oriented PET film of the present invention will be described.

  In the present invention, the material constituting the hard coat layer is not particularly limited as long as it transmits visible light, but preferably has a high light transmittance. Examples of materials used include acrylic resins, polycarbonate resins, vinyl chloride resins, polyester resins, urethane resins, and actinic radiation curable resins. In particular, acrylic resins, urethane resins, and actinic radiation curable resins can be suitably used in terms of scratch resistance, productivity, and the like.

  The actinic radiation curable resin used as a constituent component of the hard coat layer according to the present invention includes, for example, pentaerythritol tri (meth) acrylate and pentaerythritol tetra (meth) as monomer components constituting the actinic radiation curable resin. Acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, trimethylolpropane tri (meth) acrylate, bis (meth) Cloylthiophenyl) sulfide, 2,4-dibromophenyl (meth) acrylate, 2,3,5-tribromophenyl (meth) acrylate, 2,2-bis (4- (meth) acryloyloxyphenyl) Propane, 2,2-bis (4- (meth) acryloyloxyethoxyphenyl) propane, 2,2-bis (4- (meth) acryloyloxydiethoxyphenyl) propane, 2,2-bis (4- (meth) Acryloylpentaethoxyphenyl) propane, 2,2-bis (4- (meth) acryloyloxyethoxy-3,5-dibromophenyl) propane, 2,2-bis (4- (meth) acryloyloxydiethoxy-3,5 -Dibromophenyl) propane, 2,2-bis (4- (meth) acryloyloxypentaethoxy-3,5-dibromophenyl) propane, 2,2-bis (4- (meth) acryloyloxyethoxy-3,5- Dimethylphenyl) propane, 2,2-bis (4- (meth) acryloyloxyethoxy-3-phenyl) Nyl) propane, bis (4- (meth) acryloyloxyphenyl) sulfone, bis (4- (meth) acryloyloxyethoxyphenyl) sulfone, bis (4- (meth) acryloyloxypentaethoxyphenyl) sulfone, bis (4- (Meth) acryloyloxyethoxy-3-phenylphenyl) sulfone, bis (4- (meth) acryloyloxyethoxy-3,5-dimethylphenyl) sulfone, bis (4- (meth) acryloyloxyphenyl) sulfide, bis (4 -(Meth) acryloyloxyethoxyphenyl) sulfide, bis (4- (meth) acryloyloxypentaethoxyphenyl) sulfide, bis (4- (meth) acryloyloxyethoxy-3-phenylphenyl) sulfide, bis (4- (meta Acu Use of polyfunctional (meth) acrylic compounds such as loyloxyethoxy-3,5-dimethylphenyl) sulfide, di ((meth) acryloyloxyethoxy) phosphate, tri ((meth) acryloyloxyethoxy) phosphate These can be used alone or in combination of two or more.

  In addition to these polyfunctional (meth) acrylic compounds, styrene, chlorostyrene, dichlorostyrene, bromostyrene, dibromostyrene, divinylbenzene are used to control the hardness, transparency, strength, refractive index, etc. of actinic radiation curable resins. , Vinyl toluene, 1-vinyl naphthalene, 2-vinyl naphthalene, N-vinyl pyrrolidone, phenyl (meth) acrylate, benzyl (meth) acrylate, biphenyl (meth) acrylate, diallyl phthalate, dimethallyl phthalate, diallyl biphenylate, or barium A reaction product of a metal such as lead, antimony, titanium, tin, or zinc and (meth) acrylic acid can be used. These may be used alone or in combination of two or more.

  In the present invention, the description “(meth) acrylic compound” is an abbreviation of “methacrylic compound and acrylic compound”, and the same applies to other compounds.

  As a method of curing the actinic radiation curable resin in the present invention, for example, a method of irradiating ultraviolet rays can be used. In this case, about 0.01 to 10 parts by weight of photopolymerization is started with respect to the compound. It is desirable to add an agent.

  The actinic radiation curable resin used in the present invention is not limited to isopropyl alcohol, ethyl acetate, methyl ethyl ketone, etc. within the range that does not impair the effects of the present invention for the purpose of improving workability during coating and controlling the coating film thickness. An organic solvent can be blended.

  In the present invention, active rays mean electromagnetic waves that polymerize acrylic vinyl groups such as ultraviolet rays, electron beams, and radiation (α rays, β rays, γ rays, etc.), and practically, ultraviolet rays are simple and preferable. . As the ultraviolet ray source, an ultraviolet fluorescent lamp, a low-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high pressure mercury lamp, a xenon lamp, a carbon arc lamp, or the like can be used. The electron beam method is advantageous in that the apparatus is expensive and requires operation under an inert gas, but it does not need to contain a photopolymerization initiator or a photosensitizer.

  In the present invention, the thickness of the hard coat layer should be appropriately adjusted and designed according to the refractive index of the easy-adhesion layer and the hard coat layer, the intended use, and the like, and is not particularly limited. -10 μm, preferably 2-5 μm. When the thickness of the hard coat layer is within such a preferable range, the hard coat properties are sufficiently expressed, and on the other hand, the film is not curled due to shrinkage at the time of curing of the hard coat layer.

  In the present invention, it is preferable to provide an antireflection layer for suppressing flickering on the surface of the hard coat layer, or to perform an antifouling treatment for preventing contamination.

For example, a low refractive index layer as an antireflection layer may be laminated on the surface of the high refractive index hard coat layer of the optical laminated film, and this may be used as the antireflection film.
The antireflection layer is not particularly limited, but can be formed by laminating a low refractive index compound or sputtering or vapor deposition of an inorganic compound such as magnesium fluoride or silicon oxide. As for the antifouling treatment, an antifouling treatment with a silicone resin, a fluorine resin or the like can be performed.

The refractive index of the high refractive index hard coat layer is 1.60 to 1.75, preferably 1.63 to 1.75, and the refractive index of the low refractive index layer is 1.40 or less, preferably 1.35 to 1.35. 1.37 is particularly preferable from the viewpoint of improving the antireflection performance.
[Function-integrated film]
In the present invention, a hard coat layer comprising at least an actinic radiation curable resin is laminated on one surface of a biaxially oriented PET film, and the other film surface contains a pigment having a near-infrared absorbing ability. It is preferable to laminate an infrared shielding layer to form a function integrated film.

In the present invention, the near-infrared shielding layer is a laminated film composed of a composition in which a pigment having near-infrared absorption ability is dispersed in a transparent polymer resin binder,
(1) The light transmittance at a wavelength of 820 nm is 20% or less,
(2) The light transmittance at a wavelength of 850 nm is 15% or less,
(3) The light transmittance at a wavelength of 950 nm to 1150 nm is 10% or less,
It is necessary to satisfy all three conditions. The light transmittance at a wavelength of 820 nm is preferably 17% or less, the light transmittance at a wavelength of 850 nm is preferably 11% or less, and the light transmittance at a wavelength from 950 nm to 1150 nm is preferably 7% or less.

  Using a spectrophotometer “UV-2450PC” manufactured by Shimadzu Corporation (using an integrating sphere for the light receiving portion), the light transmittance at an incident angle of 0 degrees was measured, and the light transmittance at each wavelength was measured.

  As the near-infrared absorbing dye, a diimonium compound as disclosed in Japanese Patent Publication No. 43-25335 is preferable, and among them, a salt having a hexafluoroantimonate ion as a counter ion is preferably used. Specific examples include “IRG-022”, “IRG-023”, “IRG-050” and the like, which are named “KAYASORB” manufactured by Nippon Kayaku Co., Ltd.

The diimonium-based compound has a wide effective absorption wavelength region in the near-infrared region with a wavelength of 850 to 1250 nm, and a unit of the near-infrared shielding layer (g) in order to make the light transmittance at a wavelength of 950 nm to 1150 nm 10% or less. it is preferred to the content of the compound per area as 0.1 to 0.5 g / ^{m 2,} more and more preferably, 0.2 to 0.3 g / ^{m 2.} If the content is below this range, the near-infrared shielding ability will be inferior, and if the content exceeds this range, the visible light transmittance will be insufficient and the image will be dark, which is not preferable.

  As the near-infrared absorbing dye in the present invention, only the above-mentioned diimonium compound may be used, but the light transmittance at a wavelength of 820 nm alone is set to 20% or less, and the light transmittance at a wavelength of 850 nm is set to 15% or less. It is necessary to increase the content, and the visible light transmittance may be insufficient. Therefore, in the present invention, it is preferable to use one or more kinds of near-infrared absorbing dyes having an absorption maximum wavelength in the wavelength range of 800 nm to 900 nm together with the diimonium compound. Specifically, a phthalocyanine compound or a naphthalocyanine compound, a cyanine compound, a dithiol nickel complex compound having one or more substituents of a halogen group such as a primary and / or secondary amino group, an alkoxy group, and fluorine. Etc. Of these, fluorine-containing phthalocyanine compounds are preferably used from the viewpoint of light resistance and heat and humidity resistance. Specific examples include “IR-1”, “IR-10”, “IR-12”, “IR-14”, etc., which are named “EEX Color” manufactured by Nippon Shokubai Co., Ltd.

  Further, although cyanine compounds have difficulty in light resistance, as an improved dye, a dye obtained by coupling a cyanine compound and a quencher in advance to be integrated is preferably used in the present invention. Here, the quencher agent refers to an antioxidant for a near-infrared absorbing dye. By integrating, the light resistance of the cyanine compound can be improved and a high extinction coefficient characteristic of the cyanine dye can be obtained, so that the amount of the dye used can be reduced. Here, bis (1,2-dithiophenolate) copper tetra-n-butylammonium salt is preferred as the quencher because it does not impair the light resistance of the diimonium compound. Specific examples of the integrated dye of the cyanine compound and the quencher include “SD50-E04N”, “SD50-E05N” manufactured by Sumitomo Seika Co., Ltd., “TZ-111” manufactured by Asahi Denka Kogyo Co., Ltd., "TZ-114", "TZ-118" etc. are mentioned.

The content per unit area of the near-infrared absorbing dye compound having a maximum absorption wavelength in the wavelength range of 800 nm to 900 nm per unit area is determined according to the extinction coefficient of the dye used and the content of the diimonium compound. However, in order to reduce the light transmittance at a wavelength of 820 nm to 20% or less and the light transmittance at a wavelength of 850 nm to 15% or less, the content is preferably 0.01 to 0.3 g / m ² , In particular, when using an integrated pigment of a cyanine compound and a quencher agent, it is preferably 0.01 to 0.1 g / m ² . If the content is below this range, the near-infrared shielding ability is inferior, and if the content exceeds this range, the light transmittance of visible light is insufficient and the image becomes dark.

  The transparent polymer resin binder used in the present invention is substantially colorless and transparent without absorption of visible rays, and includes polyester resins, (meth) acrylic resins, (meth) acrylic urethane resins, polycarbonate resins, and the like. Of these, (meth) acrylic resins are preferred.

  The (meth) acrylic resin used in the present invention is methyl (meth) acrylate, ethyl (meth) acrylate, n- or isopropyl (meth) acrylate, n- or sec- or tert-butyl. (Meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, methylcyclohexyl (meth) acrylate, cyclododecyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate , Nonyl (meth) acrylate, decyl (meth) acrylate, hydroxyethyl (meth) acrylate, (meth) acrylic acid, itaconic acid, maleic anhydride, glycidyl (meth) acrylate, fluorine-containing ( Data) acrylate, those obtained by copolymerizing several unsaturated monomer selected from styrene are preferred. Furthermore, in order to improve the light resistance of the near-infrared absorbing dye, an unsaturated monomer having a hindered amine that is a UV-stable group (for example, ADK STAB LA-82 and LA-87 manufactured by Asahi Denka Kogyo Co., Ltd.), benzo A copolymer obtained by copolymerizing an unsaturated monomer having an ultraviolet absorbing group such as triazole, benzophenone, or triazine, or a hindered amine additive (for example, Sanol LS-765, LS- manufactured by Sankyo Lifetech Co., Ltd.) is used. 2626) or an ultraviolet absorber is preferably added to the polymerized resin.

  The (meth) acrylic resin used in the present invention preferably has a glass transition point of 80 ° C. or higher from the viewpoint of heat resistance, but is not limited thereto. In order to reduce the influence of moisture on the near-infrared absorbing pigment, the hygroscopicity of the resin is preferably 2% or less.

  Furthermore, the (meth) acrylic resin used in the present invention may be crosslinked to improve solvent resistance. In this case, a crosslinking agent such as aliphatic diisocyanate, alicyclic diisocyanate, aromatic diisocyanate or melamine is suitable. Used for. Further, a silane coupling agent may be added in order to improve the adhesion with the easy adhesion layer. Examples of the silane coupling agent include an alkoxysilane compound having an unsaturated group or an epoxy group.

  The (meth) acrylic resin used in the present invention is preferably soluble in an organic solvent, particularly soluble in methyl ethyl ketone, methyl butyl ketone, cyclohexanone, acetone, acetonitrile, ethyl acetate, butyl acetate, toluene, xylene and the like. Those are preferable, and these are used alone or as a mixed solvent of two or more. The viscosity of the (meth) acrylic resin is preferably 50 to 5000 mPa · s in consideration of workability in preparing a paint by preparing a near-infrared absorbing pigment compound, and the solid of the (meth) acrylic resin The partial concentration is preferably 10 to 50% by mass.

  Specific examples of the (meth) acrylic resin binder described above include “Dianal BR-80” manufactured by Mitsubishi Rayon Co., Ltd. and “Hals Hybrid IR-G205” manufactured by Nippon Shokubai Co., Ltd.

As the dye used for color tone correction, for example, a porphyrazine-based compound (also known as a tetraazaporphyrin compound) as disclosed in JP-A No. 2002-129052 is used in terms of light resistance, solubility in organic solvents, and extinction coefficient. Preferably used. Specific examples include “TAP-2” manufactured by Yamada Chemical Co., Ltd. The content of porphyrazine compound per unit area of the near infrared ray shielding layer is preferably from 0.03~0.07 g / ^{m 2,} more and more that a 0.04~0.06g / ^{m 2} preferable. If the content is less than this range, the color tone correcting ability is inferior, and if the content exceeds this range, the light transmittance of visible light is insufficient and the image becomes dark.

  The above-mentioned near-infrared absorbing pigment and color tone correcting pigment can be either a dye or a pigment, but it is preferable to use a dye in consideration of transparency and light transmittance of visible light. In the case of using a dye, one that dissolves in an organic solvent in which the polymer resin binder is soluble is preferable. Examples of the organic solvent include methyl ethyl ketone, methyl butyl ketone, cyclohexanone, acetone, acetonitrile, ethyl acetate, butyl acetate, toluene, xylene and the like.

  The near-infrared absorbing dye and the color tone correcting dye are used after being dissolved in the organic solvent and then mixed with a polymer resin binder solution or an organic solvent to form a paint. Furthermore, it is also preferable to mix | blend a ultraviolet absorber, a ultraviolet stabilizer, antioxidant, a leveling agent, an antifoamer, etc. with a coating material. The paint is applied onto the easy-adhesion layer of the base film by a coating method such as three reverse coaters, normal rotation or reverse gravure coater, comma coater, die coater, etc., and dried in an oven at 190 ° C. to form a film. And a near-infrared shielding layer is formed.

  Although the thickness of the near-infrared shielding layer of the present invention is not particularly limited, it is preferably 3 to 30 μm, more preferably 4 to 15 μm from the viewpoint of the coating property of the (meth) acrylic resin binder on the film. Is preferred.

That is, in the present invention, a hard coat layer comprising at least an actinic radiation curable resin is laminated on the surface of the PET film of the present invention, and a pigment having a near-infrared absorbing ability is formed on the other surface with a transparent polymer. A function-integrated film obtained by laminating a near-infrared shielding layer dispersed in a resin is preferable.
[Characteristic measurement method and effect evaluation method]
The characteristic measuring method and the effect evaluating method in the present invention are as follows.

(1) Thermal shrinkage of biaxially oriented PET film According to ASTM D1204-08 (2008), using a template from a biaxially oriented PET film before providing a hard coat layer, a near infrared shielding layer, etc., from both ends of the film sheet A film sheet of 250 mm × 250 mm is cut from the center. A mark is provided at the midpoint of each side of the cut test sample to be used as a reference point when the final target measurement is performed, and a mark is also provided at a position of 100 mm from each vertex to each side. The distances between the marks at the three points in the longitudinal direction and at the three points in the width direction are measured. Then, after adjusting the test sample at 23 ± 2 ° C. and humidity 50 ± 10% for 40 hours or more, heat treatment is performed for a predetermined time in an oven at a predetermined temperature horizontally and without applying a load. The distance of the mark was measured, and the thermal shrinkage rate at three points in the film longitudinal method was calculated by the following formula. The average value is obtained in the same manner for the three points in the width direction.
Thermal shrinkage (%) = (Point distance before heat treatment−Point distance after heat treatment) / Point distance before heat treatment × 100
Further, in the same manner, the heat shrinkage rate at two ends of the biaxially oriented PET film is measured, the average is obtained, and the average value at the center and both ends is obtained.

(2) Haze and total light transmittance of biaxially oriented PET film Measured according to JIS K 7105 (1981) using an automatic direct reading haze computer “HGM-2DP” manufactured by Suga Test Instruments Co., Ltd. In addition, this measurement is implemented with respect to biaxially oriented PET film before providing a hard-coat layer, a near-infrared shielding layer, etc.

(3) Light transmittance of a biaxially oriented PET film at a wavelength of 380 nm The light transmittance at an incident angle of 0 degree is measured using a spectrophotometer “UV-2450PC” (integrated sphere is used for the light receiving part) manufactured by Shimadzu Corporation. The light transmittance at a wavelength of 380 nm was measured. In addition, this measurement is implemented with respect to biaxially oriented PET film before providing a hard-coat layer, a near-infrared shielding layer, etc.

(4) Curling characteristics of optical laminated film An actinic radiation curable resin (Pernox Co., Ltd. XJC-0357-1: Refractive index 1.67) constituting a hard coat layer is coated with a bar coater on a biaxially oriented PET film. It is applied uniformly so that the film thickness after curing is 1.5 μm. Next, after drying for 20 seconds at 140 ° C. with hot air of 20 m / sec, a condensing high-pressure mercury lamp having an irradiation intensity of 120 W / cm set at a height of 9 cm from the surface (H03-L31 manufactured by Eye Graphics Co., Ltd.) ) Is irradiated with ultraviolet rays so that the integrated irradiation intensity becomes 300 mJ / cm ² and cured to obtain an optical laminated film in which a hard coat layer is laminated on a biaxially oriented PET film. An industrial UV checker (UVR-N1 manufactured by Nippon Battery Co., Ltd.) is used for measuring the cumulative irradiation intensity of ultraviolet rays. The obtained optical laminated film is cut into a size of 150 mm × 150 mm, and is left on a horizontal glass plate with the film convex portion down, and the vertical distance between the glass plate and the lower end of the four corners of the rising film is the minimum scale. Measurement is performed in units of 0.5 mm using a ruler, and the average value of these four measured values is taken as the curl value. Three samples are prepared, measured repeatedly, and the average value is taken as the curl value and evaluated according to the following criteria. In addition, (circle) is a pass range.
◎: 0.0 mm or more and less than 0.2 mm ○: 0.2 mm or more and less than 0.4 mm Δ: 0.4 mm or more and less than 0.6 mm x: 0.6 mm or more (5) In the curl characteristics of the function integrated film (4) A near-infrared shielding paint prepared as described below is applied to the surface opposite to the surface provided with the hard coat layer of the obtained optical laminated film using a die coater. Next, it was dried with hot air of 5 m / sec at 40 ° C. for 20 seconds, hot air of 20 m / sec at 190 ° C. for 20 seconds, and further dried with hot air of 20 m / sec at 90 ° C. for 10 seconds to form a near-infrared shielding layer having a thickness of 10 μm. Laminate to obtain a function integrated film. About the obtained function integrated film, the curl height was measured by the same method as (4). In addition, (circle) is a pass range.
◎: 0.0 mm or more and less than 0.2 mm ○: 0.2 mm or more and less than 0.4 mm Δ: 0.4 mm or more and less than 0.6 mm x: 0.6 mm or more <Preparation of Near Infrared Shielding Paint>
As a near-infrared absorbing dye, 29 parts by mass of “KAYASORB IRG-050” manufactured by Nippon Kayaku Co., Ltd., and 16 parts by mass of “EEX Color IR-10A” manufactured by Nippon Shokubai Co., Ltd. were mixed with 2000 parts by mass of methyl ethyl ketone. And dissolved. This solution was used as a transparent polymer resin binder solution, and was stirred and mixed with 2000 parts by mass of “HALS HYBRID IR-G205” (solid content concentration 29% solution) manufactured by Nippon Shokubai Co., Ltd. to prepare a near-infrared shielding paint.

  Next, although this invention is demonstrated based on an Example and a comparative example, this invention is not limited to these.

In the following examples, Examples 1, 2, 3, 6, 8, and 12-16 are read as Reference Examples 1, 2, 3, 6, 8, and 12-16.
<Example 1>
Using terephthalic acid as the acid component and ethylene glycol as the glycol component, adding to the polyester pellets that can obtain antimony trioxide (polymerization catalyst) to 300 ppm in terms of antimony atoms, performing a polycondensation reaction, limiting viscosity Polyethylene terephthalate pellets of 0.63 dl / g and carboxyl end group amount of 40 equivalents / ton were obtained (Polyester A1). Polyester A1 and UV absorber A (2,2 ′-(1,4-phenylene) bis [4H-3,1-benzoxazin-4-one] (CYTECORB UV-3638, molecular weight 369, benzoxazinone based on CYTEC) ) Was compounded with a vented twin-screw extruder so that the ultraviolet absorber was 12% by weight to obtain polyester A2 containing the ultraviolet absorber.

  Polyester A1 and polyester A2 were charged so that the UV absorber was 0.5% by weight based on the total polyester, first vacuum dried at 150 ° C. for 2 hours, and then vacuum dried at 180 ° C. for 2 hours. And melted at 285 ° C., filtered through a 3 μm cut filter, extruded into a sheet from a T-shaped die, wound around a mirror casting drum having a surface temperature of 25 ° C. using an electrostatic application casting method, and solidified by cooling. This unstretched film was heated to 90 ° C. and stretched 3.4 times in the longitudinal direction to obtain a uniaxially oriented (uniaxially stretched) film. This film was subjected to corona discharge treatment on both sides in air. Next, the easy-adhesion coating liquid a1 was applied to the surface, and the easy-adhesion coating liquid b1 was applied to the opposite surface by a metabar method using a # 4 metalling wire bar.

(Aqueous coating composition of easy-adhesion coating liquid a1)
Easy-adhesion coating liquid a1: aqueous solution having a polyester resin concentration of 1.5%: 2,6-naphthalenedicarboxylic acid / 1,2,4,5-benzenetetracarboxylic acid / 9,9-bis [ 4- (2-hydroxyethoxy) phenyl] fluorene / ethylene glycol = polyester resin comprising a copolymer composition of 37/13/45/5 mol%: 100 parts by weight, melamine cross-linking agent: 5 parts by weight, average particle size 40 nm Silica particle lubricant: 5 parts by weight (water-based coating composition of easy-adhesion coating solution b1)
Easy adhesion coating solution b1: The total concentration of the polyester resin and acrylic resin having the following components is 6.0% aqueous solution. Methyl methacrylate / ethyl acrylate / acrylic acid / N-methylol acrylamide = 63/35/1/1% by weight Acrylic resin comprising a copolymer composition of: 30 parts by weight-terephthalic acid / isophthalic acid / trimellitic acid / sebacic acid / ethylene glycol / neopentyl glycol / 1,4-butanediol = 28/9/10/3/15 / Polyester resin comprising a copolymer composition of 18/17 mol%: 70 parts by weight, melamine cross-linking agent 25 parts by weight, silica particle lubricant having an average particle size of 140 nm: 1.0 part by weight Uniaxial stretching with an easy-adhesive coating solution applied The film was held with a clip and led to a tenter.
In the tenter, first, the coating liquid was dried and the film was preheated at an atmospheric temperature (preheating temperature) of 120 ° C., and then continuously stretched 3.5 times in the width direction in a stretching zone having a stretching temperature of 120 ° C.
Subsequently, heat setting was performed in a heat setting zone having a heat setting temperature of 235 ° C. The heat setting time was 10 seconds. Subsequently, the film was cooled to 220 ° C. to 160 ° C., and a relaxation treatment was performed at a relaxation rate of 7% in the width direction (TD). Thereafter, the film was further cooled to 160 ° C. to 120 ° C., and a 0.2% fine stretching process was performed in the width direction. The film after the fine stretching treatment was cooled to 70 ° C., and then the film was taken out from the tenter to obtain a biaxially oriented PET film having a thickness of 100 μm and having completed crystal orientation. The characteristics and the like of this biaxially oriented PET film are shown in the table.

  Then, the hard-coat layer was laminated | stacked on the surface which apply | coated the easy-adhesion coating liquid A by the method as described in the said evaluation method (4) to the obtained biaxially oriented PET film, and the laminated film for optics was obtained. Thereafter, the method near-infrared shielding layer described in the evaluation method (5) was laminated on the reverse surface (the surface coated with the easy-adhesion coating liquid B) to obtain a function integrated film. Table 2 shows the properties of the obtained optical laminated film and function-integrated film.

<Examples 2 to 5>
A biaxially oriented PET film was obtained in the same manner as in Example 1 except that the production conditions of the biaxially oriented PET film were as shown in Table 1. Subsequently, using the obtained biaxially oriented PET film, an optical laminated film and a function integrated film were obtained in the same manner as in Example 1. Table 2 shows properties of the obtained biaxially oriented PET film, optical laminated film, and function-integrated film.

<Example 6>
Except that polyester A1 and polyester A2 were charged so that the UV absorber was 0.8% by weight with respect to the total polyester, and the production conditions of the biaxially oriented PET film were as shown in Table 1, Examples In the same manner as in Example 1, a biaxially oriented PET film was obtained. Subsequently, using the obtained biaxially oriented PET film, an optical laminated film and a function integrated film were obtained in the same manner as in Example 1. Table 2 shows properties of the obtained biaxially oriented PET film, optical laminated film, and function-integrated film.

<Example 7>
A biaxially oriented PET film was obtained in the same manner as in Example 6 except that the production conditions of the biaxially oriented PET film were as shown in Table 1. Subsequently, using the obtained biaxially oriented PET film, an optical laminated film and a function integrated film were obtained in the same manner as in Example 1. Table 2 shows properties of the obtained biaxially oriented PET film, optical laminated film, and function-integrated film.

<Example 8>
A biaxially oriented PET film was obtained in the same manner as in Example 1, except that polyester A1 was not used and only polyester A1 was charged and the production method of the biaxially oriented PET film was as described in the table. Subsequently, using the obtained biaxially oriented PET film, an optical laminated film and a function integrated film were obtained in the same manner as in Example 1. Table 2 shows properties of the obtained biaxially oriented PET film, optical laminated film, and function-integrated film.

<Examples 9 to 16>
A biaxially oriented PET film was obtained in the same manner as in Example 8 except that the production conditions of the biaxially oriented PET film were as shown in Table 1. Subsequently, using the obtained biaxially oriented PET film, an optical laminated film and a function integrated film were obtained in the same manner as in Example 1. Table 2 shows properties of the obtained biaxially oriented PET film, optical laminated film, and function-integrated film.

<Example 17>
The same as in Example 6 except that the easy-adhesion coating liquid a2 was applied to the surface, the easy-adhesion coating liquid b1 was applied to the opposite surface, and the production conditions of the biaxially oriented PET film were as described in Table 1. A biaxially oriented PET film was obtained. Subsequently, using the obtained biaxially oriented PET film, an optical laminated film and a function integrated film were obtained in the same manner as in Example 1. Table 2 shows properties of the obtained biaxially oriented PET film, optical laminated film, and function-integrated film.

(Aqueous coating composition of easy-adhesion coating liquid a2)
Easy adhesion coating solution a2: aqueous solution having a concentration of a polyester resin having the following components of 5.0%: terephthalic acid / 2,6-naphthalenedicarboxylic acid / 5-Nasulfoisophthalic acid / ethylene glycol / diethylene glycol = 34/10 / Polyester resin having a copolymer composition of 6/49/1 mol%: 100 parts by weight, oxazoline crosslinking agent: 6 parts by weight, melamine crosslinking agent: 40 parts by weight, silica particle lubricant having an average particle size of 140 nm: 1.2 parts by weight Part <Comparative Examples 1-18>
A biaxially oriented PET film was obtained in the same manner as in Example 8 except that the production conditions of the biaxially oriented PET film were as described in the table. Subsequently, using the obtained biaxially oriented PET film, an optical laminated film and a function integrated film were obtained in the same manner as in Example 1. Table 2 shows properties of the obtained biaxially oriented PET film, optical laminated film, and function-integrated film.
(result)
When the biaxially oriented PET film has a heat shrinkage ratio Lt (%) in the width direction at 140 ° C. for 30 minutes of more than 0.8 or less than 0, the curl property after hard coating is inferior, between 0 and 0.8. It was good. Moreover, curl properties of the hard coat film were particularly good when Lt was in the range of 0.3 to 0.6.

  On the other hand, when the heat shrinkage ratio Ht (%) in the width direction at 190 ° C. for 20 minutes of the biaxially oriented PET film exceeds 0.8, the curl property of the function integrated film deteriorated. Further, when the value of (Lt−Ht) exceeds 0.5 or less than 0, the curl property of the function integrated film is deteriorated. Moreover, when the value of Lt is 0.3 to 0.6, the value of Ht is 0 to 0.5, and (Lt−Ht) is in the range of 0.1 to 0.3, the hard coat film and the function Both integrated films gave particularly good curl properties. (Examples 4, 5, 7, 9, 10, 11, 17)

  INDUSTRIAL APPLICABILITY The present invention can be particularly suitably used for a biaxially oriented polyethylene terephthalate film used for an optical filter of a plasma display panel, and further for a function integrated film in which a hard coat, a near infrared ray shielding, and an antireflection layer are laminated. . In addition, the present invention is not limited to a functional film having a hard coat layer and a near-infrared shielding layer. It can be developed and can be suitably used for hard coat films for touch panels, surface decorative films, and protective film applications.

Claims (2)

A hard coat layer having a drying step of 100 to 150 ° C. when providing a hard coat layer using at least an actinic radiation curable resin on one side of the film, and a drying when providing near-infrared absorption on the other film side Used in a function integrated film having a near-infrared shielding layer whose process is 180 to 200 ° C., heat-shrinkage ratio Lt (%) in the film width direction when heat-treated at 140 ° C. for 30 minutes, and heat-treated at 190 ° C. for 20 minutes Is a method for producing a biaxially oriented polyethylene terephthalate film for hard coat, in which the heat shrinkage ratio Ht (%) in the film width direction satisfies the following formulas (1) to (3), and melts and extrudes polyethylene terephthalate pellets, and cools after obtaining an unstretched polyethylene terephthalate film to solidify, in the longitudinal direction and the width direction, the length at 70 to 100 ° C. Direction stretched 2.5 to 5.0 times, after stretched 3-5 times in the width direction at 70 to 150 ° C., a heat-applied to the film by heat setting zone of 200 to 250 ° C., the film While being cooled, 3 to 5 % of relaxation treatment is applied in the width direction in the range of 220 to 160 ° C., and the film is slightly stretched in the width direction of 0.5 to 1.0% in the range of 180 to 100 ° C. while cooling. And a method of producing a biaxially oriented polyethylene terephthalate film for hard coat, wherein the film is cooled to a glass transition temperature or lower.
(1) 0.0 ≦ Lt ≦ 0.6
(2) −0.2 ≦ Ht ≦ 0.8
(3) 0.0 ≦ (Lt−Ht) ≦ 0.5 2. The method for producing a biaxially oriented polyethylene terephthalate film for hard coat according to claim 1 , wherein the light transmittance at a wavelength of 380 nm is 5% or less.