JP2007152591A - Laminated thermoplastic resin film and film roll - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated thermoplastic resin film having excellent adhesion and blocking resistance, reduced in the number of extremely thin continuous elastic coating stripe flaws and the number of the optical flaws caused by lumpy foreign matter with a long diameter of 0.3 mm or above. <P>SOLUTION: In the laminated thermoplastic resin film constituted by providing a coating layer containing a resin component, which contains a copolyester resin and a polyurethane resin, and particles on one side or both sides of a thermoplastic layer, the coating layer has a structure wherein a polyester phase A based on the copolyester resin and a polyurethane phase B based on the polyurethane resin are subjected to microphase or nanophase separation with a specific PEs surface ratio and the number of the continuous elastic coating stripe flaws present in the laminated film is 30/m<SP>2</SP>or below. Further, the content of the foreign matter with a long diameter of 0.3 mm or above based on the resin component and particles of the coating layer is 30/100 m<SP>2</SP>or below. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  Various functional layers (hard coat layer, light diffusion layer, prism, etc.) such as an antireflection film, a light diffusion sheet, a prism sheet, an infrared absorption film, a transparent conductive film, and an antiglare film, which are mainly used for display-related applications. Layer, infrared absorption layer, transparent conductive layer, antiglare layer, etc.), optical functional film or optical functionality that has few optical defects due to foreign matter, and excellent blocking resistance and transparency. The present invention relates to a laminated thermoplastic resin film serving as a base material of a sheet, and a laminated thermoplastic resin film roll obtained by winding the laminated thermoplastic resin film into a roll.

  In general, as a base material of an optical functional film used for a display member such as a liquid crystal display (LCD) or a plasma display panel (PDP), polyethylene terephthalate (PET), acrylic polymer, polycarbonate (PC), triacetyl cellulose is used. A transparent film made of (TAC), polyolefin or the like is used. When these base films are used for various optical functional films, functional layers corresponding to various uses are laminated on the base film. For example, in a liquid crystal display (LCD), a protective film (hard coat layer) that prevents scratches on the surface, an antireflection layer (AR layer) that prevents reflection of external light, and a prism layer that is used to collect and diffuse light And a functional layer such as a light diffusion layer for improving luminance. Among these substrates, in particular, biaxially oriented polyester films are widely used as substrates for various optical functional films from the viewpoints of excellent transparency, dimensional stability, and chemical resistance.

  In general, in the case of a biaxially oriented thermoplastic film such as a biaxially oriented polyester film or a biaxially oriented polyamide film, the film surface is highly crystallized so that it can adhere to various paints, adhesives, inks, etc. There is a disadvantage of being scarce. For this reason, methods for imparting easy adhesion to the biaxially oriented thermoplastic resin film surface by various methods have been proposed.

  Films that do not have polar groups, such as polyolefin films, have very poor adhesion to various paints, adhesives, inks, etc., so physical and chemical treatments such as corona discharge treatment and flame treatment are performed beforehand. After being performed, methods for imparting easy adhesion to the film surface by various methods have been proposed.

  As a method for imparting easy adhesion, for example, various resins such as polyester, acrylic polymer, polyurethane, and acrylic graft polyester are used as the main constituent components of the coating layer on the surface of the thermoplastic resin film of the base material, and the coating method is used. A method of providing the coating layer on a material film is generally known. Among them, the copolymer polyester resin is generally used as a material for a coating layer because it has excellent adhesiveness with a biaxially oriented polyester film that is frequently used as a base plate film of a display diffusion plate or prism lens. In addition, as a coating method, a thermoplastic resin film before completion of crystal orientation is subjected to corona discharge treatment directly or as necessary, and then a dispersion in which the resin solution or resin is dispersed with a dispersion medium is used. A method of applying the aqueous coating liquid containing to a base film, drying, stretching at least uniaxially, then applying heat treatment to complete crystal orientation of the thermoplastic resin film (so-called in-line coating method), A method (so-called off-line coating method) in which a water-based or solvent-based coating solution is applied to the film after the production of the thermoplastic resin film and then dried (so-called off-line coating method) has been widely practiced industrially.

  LCDs, PDPs, and other displays have been increasing in size and cost year by year, and production speeds have been increased in the manufacturing process of optical functional films or optical functional sheets used as members thereof. As the manufacturing process is speeded up, stress due to curing shrinkage is more likely to occur at the interface between the functional layer such as the hard coat layer, the diffusion layer, and the prism layer and the base film. Therefore, when cutting an optical functional film or an optical functional sheet to a specific size for manufacturing a display, the problem is that the end portion is particularly easily peeled off when the adhesion at the interface is insufficient. Happened. The tendency of this tendency is that the larger the film wound up in rolls and the higher the production speed in the manufacturing process, the more the influence of the peeling of the interface due to the impact during cutting becomes more pronounced. Is becoming insufficient.

  Furthermore, the processing agent used for forming the functional layers such as the prism layer and the diffusion layer is applied directly to the base film without being diluted with an organic solvent from the viewpoint of reducing the environmental load. There are many cases. Therefore, since the wettability improvement effect of the coating layer by an organic solvent may not be obtained sufficiently, higher adhesion is required. On the other hand, in applications such as hard coat where importance is placed on smoothness, the processing agent is often diluted with an organic solvent in order to lower the viscosity of the processing agent and obtain a good leveling effect. In this case, the coating layer of the laminated thermoplastic resin film is required to have appropriate solvent resistance.

  In order to improve the adhesion between the functional layer and the substrate film, a method of using a resin having a low glass transition temperature as the resin constituting the coating layer is common. However, when a resin having a low glass transition temperature is used, the blocking resistance tends to decrease when the film is continuously wound into a roll and the film is unwound from the roll.

  In recent years, in order to reduce the cost, the size of a processing machine for laminating functional layers such as a hard coat layer and a diffusion layer on a base film has been increased, and a roll of an easily adhesive film used as a base film. The diameter is also increasing. Along with this, when winding with high tension in order to prevent roll misalignment, blocking is more likely to occur because the core of the roll is pressure-bonded with high pressure.

  In order to improve the blocking resistance, a method of providing irregularities on the film surface and reducing the contact area is generally employed. In order to give unevenness to the film surface, a method of increasing the content of inorganic particles or organic particles contained in the coating layer or the base film, or a method of using particles having a large particle size is common. However, the refractive index of commercially available particles is generally different from the refractive index of the resin used for the coating layer, and voids are formed around the particles as the film is stretched. , Film light transmittance decreases, haze increases, and the like. In particular, the transparency required for the optical functional film or the base film of the optical functional sheet is lowered. In other words, with conventional methods, it is extremely difficult to improve adhesion and blocking resistance with a functional layer while maintaining transparency due to new problems associated with higher process speeds and larger roll diameters of films. Met.

  Furthermore, displays such as LCDs and PDPs are not only increased in size and cost, but also have been increasing in brightness in order to display images vividly year by year. Under such circumstances, in the optical film, even a very thin optical defect that has not been conspicuous in the past has come to the surface. Further, if this defective part is a defective product, the display is enlarged. As a result, the product yield of optical films is greatly reduced, so that reduction of optical defects is required. In addition, even if it is a thin defect that has not been a problem in the prior art, the continuous application stripe defect tends to be conspicuous, and improvement has been strongly demanded.

  The coating layer contains particles for the purpose of imparting easy slipperiness, and in order to display an image vividly, the particles often use fine particles with small light scattering of visible light. For this reason, films that are highly transparent and have a low haze, that is, excellent optical properties, tend to be noticeable even with extremely thin continuous streaks.

  In general, a method of irradiating a coating surface with bromolite (illumination equipment used for taking a photograph or video) on the film surface and visually observing the reflected light is used to detect the coating stripe defect. Since the light emits strong light, it may be overlooked in the case of very thin application streaks. In addition, the present inventors can experience high detection accuracy by empirically irradiating bromolite on the side opposite to the coating surface and observing from the coating surface side to detect the continuous coating streaks defined by the present invention. I know that.

  Furthermore, the light source used particularly for the liquid crystal panel is mainly a three-wavelength fluorescent tube, and even if a laminated film in which continuous coating streaks are not detected by the bromolite inspection is used, a hard coat layer is laminated, an AR film, In some cases, the continuous application streaks become obvious after processing into a lens film, and when they are incorporated into a display, they may be visually recognized as thin continuous application streaks.

  In the present invention, the continuous coating streaks defects are extremely thin, and are detected using a three-wavelength fluorescent tube in a dark room under specific conditions described later, and detected using bromolite in the same environment. This means a coating streak in which nuclei are connected as shown in Fig. 7-1, which is detected by combining both methods. The resin component spreads in the shape of a mountain around one nucleus. There are many things. FIG. 7-2 is an enlarged view of the nucleus of FIG. 7-1, and FIG. 8 is a diagram showing irregularities including one nucleus and the surrounding crest portion. In addition, the continuous coating streaks defined by the present invention includes those having a core portion divided into a plurality of parts. In addition, the continuous coating streaks defined in the present invention are coarse particles in which particle aggregates present in the coating solution that can be detected relatively easily using only bromolite are densely scattered on the film and further scattered in streaks. The application stripe defect is different in size and shape, and also has a different generation mechanism. The reason for the presence of the continuous application streak that is easier to detect when using bromolite and the repetitive application streak that is easier to detect using the three-wavelength fluorescent tube is obvious. However, it is assumed that the height of the nucleus and the size of the ridge that exists around the nucleus are involved.

  Such a continuous coating streak defect is an extremely thin defect that cannot be detected by an in-line defect inspection machine, and it has been extremely difficult to improve it while maintaining excellent optical characteristics.

The following is a specific look at the prior art. Generally, the biaxially oriented polyester film has poor adhesion to a coating agent mainly composed of an acrylic resin used for prism lenses, hard coats, etc. It has been known. For this reason, various things which formed the coating layer which consists of a polyurethane resin etc. on the surface of the polyester film are proposed (for example, refer patent document 1).
However, particles are added to the coating layer in order to impart slipperiness. In order to maintain the haze and transparency of the laminated film, these particles have a relatively small average primary particle size of about 0.01 to 0.1 μm. However, the smaller the particle size, the easier it is to agglomerate, which is one factor of optical defects due to coarse aggregates. In addition, when a coating layer made of polyurethane resin is formed, the adhesion with a functional layer such as a hard coat layer is improved, but the adhesion with a polyester film as a substrate is not sufficient, resulting in coating. There was a problem that the adhesion was insufficient at the interface between the layer and the functional layer. Furthermore, foreign substances such as dust and particle aggregates for the purpose of imparting slipperiness may be mixed in or adhered to the inside of the coating layer or the surface of the coating layer, often resulting in optical defects.

  The present applicants perform high-precision filtration treatment on the coating resin for laminating the molten resin and the resin composition when forming the base film, and on the base film made of biaxially oriented polyethylene terephthalate, the polyester resin Adhesion at the required level from the market while maintaining transparency, which is a very important characteristic for optical substrate films, with a resin composition layer that contains polyurethane resin and inorganic particles of moderate particle size The laminated polyester film which can fully satisfy the property and has few optical defects has been proposed (see, for example, Patent Documents 2 and 3). Specifically, a polyester film obtained by using a polyethylene terephthalate resin filtered with a stainless steel sintered filter medium having a filtration particle size (initial filtration efficiency of 95%) 15 μm is copolymerized with a polyester film stretched uniaxially in the longitudinal direction. A water-dispersible coating liquid containing a polyester resin, a polyurethane resin (= 20/80; mass%), two kinds of particles having a primary average particle diameter of 40 nm and an anionic surfactant is filtered with a filter particle size (initial filtration efficiency 95). %) An easy-adhesive biaxially oriented polyester film obtained by filtering with a felt type polypropylene filter medium of 25 μm, coating, guiding to a tenter, drying, transverse stretching, and heat setting at 240 ° C. was disclosed.

  The easy-adhesive biaxially stretched polyester film obtained by the invention described in the patent document has excellent adhesion, blocking resistance and transparency, and has optical defects such as foreign matter and scratches, and in the coating solution. Optical defects due to the contained coarse particle aggregate having a size of 100 μm or more can be greatly reduced. However, as mentioned above, the substrate film and the hard coat which are required as the optical functional film or the substrate film for the optical functional sheet in accordance with the recent cost reduction, the increase in the brightness of the display and the enlargement of the large screen. The required level for adhesion to functional layers such as layers, diffusion layers, and prism layers, and blocking resistance tends to be stricter year by year, and it is no longer sufficient to satisfy the required quality of the current market. Furthermore, the quality required for reducing extremely thin continuous defects and the required quality in the current market where optical defects that are relatively small (0.3 mm or more) are unacceptable cannot be sufficiently met. It was coming.

As described above, the conventional technology cannot sufficiently satisfy the adhesiveness that can withstand high-speed cutting required in recent years and the blocking resistance that can cope with the enlargement of the film roll diameter while maintaining high transparency. It was coming. In addition, the thin repetitive coating streaks defined by the present invention are more conspicuous as the haze is smaller and the transparency is higher, and it is extremely difficult to achieve both excellent optical properties and reduction of thin repetitive defects. Met. Further, the cause of the occurrence of the above optical defects is unknown, and no matter how high-precision filtration is performed on the coating liquid, the optical defects cannot be reduced only by the filtration treatment.
JP-A-6-340049 JP 11-323271 A JP 2000-246855 A

  Accordingly, in view of the above-mentioned problems, the object of the present invention is a lamination heat having excellent adhesion and blocking resistance, and having extremely thin continuous coating streaks defects and optical defects due to massive foreign matters having a major axis of 0.3 mm or more. The object is to provide a plastic resin film.

The object of the present invention is achieved by the following achievement means.
[1] A laminated thermoplastic resin film having a coating layer containing a resin component and particles containing a copolyester resin and a polyurethane resin on one side or both sides of a thermoplastic resin film,
The coating layer has a structure in which a polyester phase A mainly composed of a copolymerized polyester resin and a polyurethane phase B mainly composed of a polyurethane resin are microphase-separated or nanophase-separated, and a scanning probe When the microscope is observed in the phase measurement mode, the area ratio (PEs surface fraction) of the polyester phase A (indicating a dark hue in the phase image) defined by the following formula (1) is 5 μm × A defect having a core defined by the following formulas (2) and (3), which is 35% or more and less than 90% in a measurement area of 5 μm and is present in the laminated film, is represented by the following formulas (4) and (5). The number of continuous coated streak defects that are continuous in a defined state is 30 / m ² or less, and the content of massive foreign matters having a major axis of 0.3 mm or more whose major component is a coating layer resin component and particles. , 30 / 100m ² Laminated thermoplastic resin film which is a lower.
PEs surface fraction (%) = (Area of polyester phase A / Measurement area) × 100 (1)
10 ≦ Dd ≦ 35 (2)
30 ≦ Dt ≦ 5000 (3)
n ≧ 2 (4)
t ≧ 10mm (5)
Dd: Core major axis (μm)
Dt: Maximum height of the nucleus (nm)
n: number of nuclei defined by the formula (2) and the formula (3) per mm of the continuous coated muscle defect t: length of the continuous coated muscle defect [2] copolymer polyester resin and polyurethane resin The laminated thermoplastic resin film according to the above [1], wherein the mass ratio of the copolymerized polyester resin and the polyurethane resin of the resin component containing 70/30 to 30/70.
[3] The laminated thermoplastic resin film according to [1] or [2], wherein the copolyester resin is a copolyester resin having a low content of low molecular weight components.
[4] A copolymer polyester resin is obtained by filtering a solution of a copolymer polyester resin through a filter having a filtration particle size of 0.5 μm or more and 10 μm or less under a liquid temperature of 15 ° C. or more and less than 35 ° C., and 50 ° C. As described above, after heating to less than 70 ° C. and further filtering through a filter having a filtration particle size of 0.5 μm or more and 10 μm or less under conditions of 15 ° C. or more and less than 35 ° C., the above [ [3] The laminated thermoplastic resin film according to [3].
[5] The surface of the coating layer is observed in a phase measurement mode of a scanning probe microscope, and in a phase image in which the outline of the interface between the light hue and the dark hue is emphasized, the light hue and the dark hue are detected using a box counting method. The laminated thermoplastic resin film according to any one of the above [1] to [4], wherein the fractal dimension obtained from the boundary line (interface contour) is 1.60 to 1.95 in a measurement area of 5 μm × 5 μm.
[6] The laminated thermoplastic resin film according to any one of [1] to [5], wherein the particles contained in the coating layer are particles made of silicon oxide.
[7] The laminated thermoplastic resin film according to any one of [1] to [6], wherein the thermoplastic resin film base material contains substantially no particles.
[8] The laminated thermoplastic resin film according to any one of [1] to [7], wherein the particles in the coating layer are unevenly distributed in the polyester phase A or the polyurethane phase B.
[9] The laminated thermoplastic resin film according to any one of [1] to [8], wherein the thermoplastic resin film is a biaxially oriented polyester film or a biaxially oriented polyamide film.
[10] The laminated thermoplastic resin film according to any one of [1] to [9], wherein the hardness index of the coating layer defined below is 3.0 to 15.0 nm.
The coating layer hardness index is a needle with a sapphire with a radius of 75 μm at the tip, and the surface of the coating layer is scratched by applying a weight of 5 gf. Means the average value of 50 measured values of the height difference between adjacent convex portions and concave portions.
[11] The laminated thermoplastic resin film according to any one of [1] to [10], wherein the haze is 1.5% or less.
[12] The laminated thermoplastic resin film according to any one of [1] to [11], which is used as an optical functional film or a base film for an optical functional sheet.
[13] The above-mentioned [12], wherein the optical functional film or optical functional sheet is a hard coat film, an antireflection film, a light diffusion sheet, a prism sheet, a transparent conductive film, a near-infrared absorbing film, or an electromagnetic wave absorbing film. Laminated thermoplastic resin film.
[14] The laminated thermoplastic resin film according to any one of [1] to [13], wherein a functional layer containing an acrylic resin as a main constituent component is laminated on at least one surface of the coating layer.
[15] A laminated thermoplastic resin film roll obtained by winding up the laminated thermoplastic resin film according to any one of [1] to [14].
[16] The laminated thermoplastic resin film roll according to [15], wherein the winding length is 1500 m or more and the width is 0.5 m or more.

  The laminated thermoplastic resin film of the present invention comprises two types of resins constituting the coating layer, that is, a copolymerized polyester-based resin and a polyurethane-based resin comprising a polyester phase A and a polyurethane-based resin whose main component is a copolymerized polyester-based resin. The polyurethane phase B as the main component has a specific microphase separation structure or nanophase separation structure, and the area ratio (PEs surface fraction) of the polyester phase A on the surface of the coating layer is in a specific range. It is excellent in adhesion and blocking resistance with functional layers such as a hard coat layer, a diffusion layer, and a prism layer.

  Further, transparency can be improved by containing a specific amount of particles having a specific particle size only in the coating layer or by making the particles unevenly distributed in either the polyester phase A or the polyurethane phase B on the surface of the coating layer. While maintaining a high level, it is possible to improve blocking resistance, handling property, and scratch resistance. In particular, when silica particles are contained in the coating layer, silica particles can be unevenly distributed in the polyurethane phase, so that it is possible to compensate for the disadvantages of polyurethane having poor blocking resistance.

  Furthermore, the laminated thermoplastic resin film of the present invention has the characteristics that there are few optical defects due to continuous coating streaks defects and massive foreign matters having a major axis of 0.3 mm or more, and is excellent in optical characteristics.

  Therefore, the laminated thermoplastic resin film of the present invention is an optical functional film such as a hard coat film, an antireflection (AR) film, a light diffusion sheet, a prism lens sheet, a transparent conductive film, an infrared absorption film, an electromagnetic wave absorption film, and the like. Or it is suitable as a base film of an optical functional sheet. Moreover, it can be used also as a film for printing printed using UV ink which uses an acrylic resin as a resin component.

Embodiments of the present invention will be described below.
The present invention is a laminated thermoplastic resin film having a coating layer containing a resin component and particles containing a copolymerized polyester resin and a polyurethane resin on one side or both sides of a thermoplastic resin film, the coating layer Has a structure in which a polyester phase A mainly composed of a copolyester resin and a polyurethane phase B mainly composed of a polyurethane resin are microphase-separated or nanophase-separated, and a scanning probe microscope is used as a phase. Measurement in which the area ratio (PEs surface fraction) of the polyester phase A (indicating a dark hue in the phase image) defined by the following formula (1) when observed in the measurement mode is 5 μm × 5 μm A defect having a core defined by the following formulas (2) and (3), which is 35% or more and less than 90% in area and present in the laminated film, has the following formulas (4) and (4): ) The number of duet shaped coating muscle drawbacks continuous state as defined in the, it is 30 present / m ² or less, further containing the major axis 0.3mm or more bulk foreign matter mainly containing coating layer resin component and particles It is a laminated thermoplastic resin film characterized in that the amount is 30 pieces / 100 m ² or less.
PEs surface fraction (%) = (Area of polyester phase A / Measurement area) × 100 (1)
10 ≦ Dd ≦ 35 (2)
30 ≦ Dt ≦ 5000 (3)
n ≧ 2 (4)
t ≧ 10mm (5)
Dd: Core major axis (μm)
Dt: Maximum height of the nucleus (nm)
n: Number of nuclei defined by the formula (2) and the formula (3) per 1 mm of the continuous applied muscle defect t: Length of the continuous applied muscle defect

(Thermoplastic resin film; base film)
In the present invention, the thermoplastic resin film as a base material is a non-oriented sheet obtained by melt extrusion or solution extrusion of a thermoplastic resin, if necessary, stretched in a longitudinal direction or a uniaxial direction in the width direction, or A film that has been biaxially stretched in the biaxial direction or simultaneously biaxially stretched and heat-set.

  The thermoplastic resin film may be subjected to surface activation treatment such as corona discharge treatment, glow discharge treatment, flame treatment, ultraviolet ray irradiation treatment, electron beam irradiation treatment, ozone treatment, etc., as long as the object of the present invention is not impaired. Good.

  The thickness of the thermoplastic resin film used as the substrate can be arbitrarily determined in the range of 30 to 300 μm according to the standard of the application to be used. The upper limit of the thickness of the thermoplastic resin film is preferably 250 μm, particularly preferably 200 μm. On the other hand, the lower limit of the film thickness is preferably 50 μm, particularly preferably 75 μm. When the film thickness is less than 30 μm, rigidity and mechanical strength tend to be insufficient. On the other hand, when the film thickness exceeds 300 μm, the absolute amount of foreign matter present in the film increases, and thus the frequency of optical defects increases. Moreover, the slit property at the time of cut | disconnecting a film to a predetermined width also deteriorates, and manufacturing cost becomes high. Furthermore, since rigidity becomes strong, it becomes difficult to wind a long film in a roll shape.

  Thermoplastic resins include polyolefins such as polyethylene (PE), polypropylene (PP), and polymethylpentene (TPX), polyethylene terephthalate (PET), polyethylene-2,6-naphthalate (PEN), polypropylene terephthalate (PTT), poly Polyester resins such as butylene terephthalate (PBT), polyamide (PA) resins such as nylon 6, nylon 4, nylon 66, nylon 12, polyimide (PI), polyamideimide (PAI), polyethersulfone (PES), poly Ether ether ketone (PEEK), polycarbonate (PC), polyarylate (PAR), cellulose propionate, polyvinyl chloride (PVC), polyvinylidene chloride, polyvinyl alcohol (PVA), poly Teruimido (PEI), polyphenylene sulfide (PPS), polyphenylene oxide, polystyrene (PS), syndiotactic polystyrene, and norbornene-based polymer. These thermoplastic resins may be copolymers containing a small amount of a copolymer component. In addition to using these thermoplastic resins alone, one or more other thermoplastic resins may be blended and used.

  Among these thermoplastic resins, polyethylene terephthalate, polybutylene terephthalate, polypropylene terephthalate, polyethylene-2,6-naphthalate, syndiotactic polystyrene, norbornene polymer, polycarbonate, polyarylate and the like are preferable. In addition, a resin having a polar functional group such as polyester or polyamide is preferable from the viewpoint of adhesion to the coating layer. In particular, polyethylene terephthalate, polyethylene-2,6-naphthalate, polybutylene terephthalate, polypropylene terephthalate or a copolymer mainly composed of these resin components is preferably used as the base material, but is formed from polyethylene terephthalate. A biaxially oriented film is most preferred.

  When a polyester copolymer is used as a resin for forming a thermoplastic resin film, for example, as its carboxylic acid component, aliphatic dicarboxylic acids such as adipic acid and sebacic acid, terephthalic acid, isophthalic acid, phthalic acid, and 2,6 -Aromatic dicarboxylic acids such as naphthalenedicarboxylic acid, polyfunctional carboxylic acids such as trimellitic acid and pyromellitic acid are used. The glycol component includes fatty acid glycols such as ethylene glycol, diethylene glycol, 1,4-butanediol, propylene glycol and neopentyl glycol; aromatic glycols such as p-xylene glycol; alicyclic rings such as 1,4-cyclohexanedimethanol Group glycol; polyethylene glycol having an average molecular weight of 150 to 20,000 is used. As an example of the copolymer composition ratio, the monomer component constituting polyethylene terephthalate is less than 20 mol% of other comonomer components (in the case where the comonomer component is a carboxylic acid component, in the total carboxylic acid component. The same applies to the case of a glycol component). If it is 20 mol% or more, the film strength, transparency, and heat resistance may be inferior. A predetermined amount of the above carboxylic acid component and glycol component is prepared, and the catalyst is, for example, an alkaline earth metal compound, a manganese compound, a cobalt compound, an aluminum compound, an antimony compound, a titanium compound, a titanium / silicon composite oxide, germanium. A polyester copolymer is produced using a compound or the like.

  Moreover, when manufacturing a base material, a catalyst and various additives other than that can be mix | blended with the said thermoplastic resin in the range which does not prevent the effect of this invention. Examples of additives include inorganic particles, heat-resistant polymer particles, alkali metal compounds, alkaline earth metal compounds, phosphorus compounds, antistatic agents, UV absorbers, light proofing agents, flame retardants, thermal stabilizers, and antioxidants. , Antigelling agents, surfactants and the like.

  The inorganic particles and the heat-resistant polymer particles are used in the production of a thermoplastic resin film or handling properties (sliding property, running property, blocking property, associated air at the time of winding) when winding in a roll. It is used for imparting appropriate surface irregularities to the film surface from the viewpoint of air release properties.

  Inorganic particles include calcium carbonate, calcium phosphate, amorphous silica, crystalline glass filler, kaolin, talc, titanium dioxide, alumina, silica-alumina composite oxide particles, barium sulfate, calcium fluoride, lithium fluoride, zeolite , Molybdenum sulfide, mica and the like. Examples of the heat resistant polymer particles include crosslinked polystyrene particles, crosslinked acrylic resin particles, crosslinked methyl methacrylate particles, benzoguanamine / formaldehyde condensate particles, melamine / formaldehyde condensate particles, and polytetrafluoroethylene particles. .

  When using a polyester film as a base film, among the above particles, silica particles are relatively close to the polyester-based resin and easily obtain a high transparency, and thus are most suitable for applications where transparency is strongly required. is there. Moreover, the particle | grains contained in a thermoplastic resin film may use 1 type, or may use multiple types together.

  The type, average particle size, and addition amount of the particles may be determined according to the application from the viewpoint of balance between transparency and handling properties. In particular, the average particle size is 0.01 to 2 μm, and the particles contained in the film What is necessary is just to determine the quantity in the range of 0.01-5.0 mass%. In addition, when the laminated thermoplastic resin film of the present invention is used for applications where transparency is highly required, the thermoplastic resin film of the base material substantially contains particles that cause a decrease in transparency. It is preferable to make it the structure which does not contain (namely, does not mix | blend particle | grains with a base material) and makes a coating layer contain particle | grains. “Substantially no particles are contained in the thermoplastic resin film of the substrate” means, for example, in the case of inorganic particles, 50 ppm or less, preferably 10 ppm when inorganic elements are quantified by fluorescent X-ray analysis. Hereinafter, it means the content that is most preferably below the detection limit. This is because contaminants derived from foreign substances may be mixed without positively adding particles to the base film.

  Moreover, the layer structure of the thermoplastic resin film used as a substrate in the present invention may be a single layer, or may be a laminated structure in order to provide a function that cannot be obtained by a single layer. In the case of a laminated structure, a coextrusion method is preferable.

  As a manufacturing method of the thermoplastic resin film of a base material, the following method is mentioned, for example. The thermoplastic resin pellets containing or substantially not containing particles are sufficiently dried in vacuum, then supplied to an extruder, melt-extruded into a sheet at a temperature higher than the melting temperature, cooled and solidified, and unoriented thermoplastic A resin sheet is formed. At this time, high-precision filtration is performed at any place where the molten resin is removed in order to remove foreign substances contained in the resin. The obtained unoriented sheet is stretched 2.5 to 5.0 times in the longitudinal direction with a roll heated to the glass transition point or higher to obtain a uniaxially oriented thermoplastic resin film.

  Furthermore, the manufacturing method for obtaining a base film is demonstrated in detail below by making into a typical example the case where polyester is used as a raw material of a thermoplastic resin film.

  The intrinsic viscosity of the polyester pellets used as the base film raw material is preferably in the range of 0.45 to 0.7 dl / g. More preferably, from the viewpoint of mechanical strength and film formation stability, the intrinsic viscosity is 0.50 dl / g to 0.7 dl / g, more preferably 0.55 to 0.7 dl / g, and most preferably 0.60. -0.7 dl / g. When the intrinsic viscosity is less than 0.45 dl / g, the film tends to be broken during the production of the film and the productivity is lowered, and the heat shrinkage property tends to be lowered. On the other hand, if the intrinsic viscosity exceeds 0.7 dl / g, the increase in filtration pressure is large and high-precision filtration becomes difficult, and productivity is lowered.

  Moreover, when using for an optical functional film or sheet | seat, it is preferable to remove the foreign material contained in the raw material polyester which causes an optical defect. In order to remove foreign substances in the polyester, high-precision filtration is performed at an arbitrary place where the molten resin is maintained at about 280 ° C. during melt extrusion. The filter medium used for high-precision filtration of the molten resin is not particularly limited, but agglomerates mainly composed of Si, Ti, Sb, Ge, and Cu and high-melting-point organic substances in the case of a stainless steel sintered filter medium are removed. Excellent performance and suitable.

  The filter particle size (initial filtration efficiency: 95%) of the filter medium used for high-precision filtration of the molten resin is preferably 15 μm or less. When the filter particle size of the filter medium exceeds 15 μm, removal of foreign matters of 20 μm or more tends to be insufficient. Productivity may be reduced by performing high-precision filtration of molten resin using a filter medium having a filtration particle size (initial filtration efficiency: 95%) of 15 μm or less, but it is extremely difficult to obtain a film with few optical defects. is important.

  In the molten resin extrusion process, even fine foreign matter that passes through the filter medium is crystallized around the foreign matter in the cooling process of the sheet-like melt. A difference in thickness is generated to cause a lens state. Here, the light is refracted or scattered as if it were a lens, and when viewed with the naked eye, it appears larger than the actual foreign object. This minute difference in thickness can be observed as the difference between the height of the convex part and the depth of the concave part. The height of the convex part is 1 μm or more and the depth of the concave part adjacent to the convex part is 0.5 μm or more. In this case, due to the lens effect, an object having a size of 20 μm may be visually recognized as a size of 50 μm or more, and may be recognized as an optical defect of a size of 100 μm or more.

  In order to obtain a highly transparent film (especially a film having a haze of 1.5% or less), it is preferable not to contain particles in the base film, but the smaller the particle content and the higher the transparency, the smaller the unevenness. Optical defects tend to be clearer.

  In addition, since the surface of a thick film is less likely to be cooled rapidly than a thin film and crystallization tends to proceed, it is necessary to rapidly cool the entire film when manufacturing an unoriented sheet. As a method for cooling the non-oriented sheet, there is a method in which the molten resin is extruded into a sheet form from the slit portion of the fountain die onto the rotating cooling drum, and the sheet-like melt is brought into close contact with the rotating cooling drum and rapidly cooled into a sheet. Is preferred. As a method of cooling the air surface (the surface opposite to the surface in contact with the cooling drum) of the unoriented sheet, a method of cooling by blowing a high-speed air stream is effective.

  The obtained unoriented sheet is stretched 2.5 to 5.0 times in the longitudinal direction with a roll heated to a glass transition point or higher to obtain a uniaxially oriented thermoplastic resin film (in this example, a polyester film).

(Copolymerized polyester resin)
The copolymerized polyester resin used in the coating layer of the present invention preferably comprises an aromatic dicarboxylic acid component and ethylene glycol and branched glycol as the glycol component. Examples of the branched glycol component include 2,2-dimethyl-1,3-propanediol, 2-methyl-2-ethyl-1,3-propanediol, and 2-methyl-2-butyl-1,3. -Propanediol, 2-methyl-2-propyl-1,3-propanediol, 2-methyl-2-isopropyl-1,3-propanediol, 2-methyl-2-n-hexyl-1,3-propanediol 2,2-diethyl-1,3-propanediol, 2-ethyl-2-n-butyl-1,3-propanediol, 2-ethyl-2-n-hexyl-1,3-propanediol, 2, Such as 2-di-n-butyl-1,3-propanediol, 2-n-butyl-2-propyl-1,3-propanediol, and 2,2-di-n-hexyl-1,3-propanediol. And the like.

  The molar ratio of the branched glycol component is preferably 10 mol%, particularly preferably 20 mol%, based on the total glycol component. On the other hand, the upper limit is preferably 80 mol%, more preferably 70 mol%, and particularly preferably 60 mol%. If necessary, diethylene glycol, propylene glycol, butanediol, hexanediol, 1,4-cyclohexanedimethanol or the like may be used in combination.

  As the aromatic dicarboxylic acid component, terephthalic acid and isophthalic acid are most preferred. Other aromatic dicarboxylic acids, particularly aromatic dicarboxylic acids such as diphenylcarboxylic acid and 2,6-naphthalenedicarboxylic acid may be added and copolymerized within a range of 10 mol% or less with respect to the total dicarboxylic acid component. .

  In producing the copolyester, a polymerization catalyst such as an antimony compound, an aluminum compound, a titanium compound, or a germanium compound can be used.

  As the copolymer polyester resin used as the resin component of the coating layer in the present invention, it is preferable to use a water-soluble or water-dispersible resin. Therefore, in addition to the dicarboxylic acid component, in order to impart water dispersibility to the polyester, 5-sulfoisophthalic acid or an alkali metal salt thereof is used in the range of 1 to 10 mol% with respect to the total dicarboxylic acid component. Examples thereof include sulfoterephthalic acid, 5-sulfoisophthalic acid, 4-sulfonaphthalene-2,7-dicarboxylic acid and 5- (4-sulfophenoxy) isophthalic acid or alkali metal salts thereof. Can do.

  Generally, copolymer polyester resins include aromatic dicarboxylic acid components (for example, terephthalic acid) and ethylene glycol trimers, pentamers, hexamers, and aromatic dicarboxylic acid components (for example, terephthalic acid). In addition, a low molecular weight component such as a tetramer of a branched glycol (for example, neopentyl glycol) is contained in a large amount. As will be described later, this low molecular weight component and particle aggregate, and in some cases, from a polymerization catalyst of a copolyester. The generated metal oxide, metal hydroxide, etc. are dried and solidified on the applicator roll or metalling roll as a mixture and deposited on the surface of the doctor blade, which falls off the doctor blade and passes through the coater roll or directly. It is presumed that the above-mentioned serious optical defect occurs due to adhesion to the base film. Therefore, the present invention stipulates that the content of the low molecular weight component (component of hexamer or less) of the copolyester resin in the coating solution is reduced, thereby reducing the precipitation of solid matter on the doctor blade. This is important in obtaining a thermoplastic resin film roll with few optical defects.

  Therefore, in the present invention, a copolymer polyester resin having a reduced content of low molecular weight components is used. The method for reducing the content of the low molecular weight component of the copolymer polyester resin is not particularly limited, but the copolymer polyester resin is dissolved in a solvent to form a solution, and the solution temperature is 15 ° C. or more and less than 35 ° C. After filtering with a filter having a filter particle size of 0.5 μm or more and 10 μm or less under the conditions of A method of filtering with a filter of 5 μm or more and 10 μm or less is preferable.

  The solvent for dissolving the copolyester resin in a solvent to form a solution is not particularly limited as long as the copolyester resin is dissolved. For example, for a water-soluble or water-dispersible polyester resin, Alcohols such as ethanol, isopropyl alcohol, and benzyl alcohol can be preferably used, and water and isopropyl alcohol are most preferable.

  For example, a solvent is added to the copolymerized polyester resin and stirred to obtain a solution of the copolymerized polyester resin having a solid content concentration of 20 to 40% by mass, preferably 25 to 35% by mass. This solution is allowed to stand as it is to precipitate coarse oligomer aggregates. The standing time is preferably 5 to 20 days, and the temperature during standing is preferably less than 35 ° C. If it is 35 ° C. or higher, the low molecular weight resin component may not be sufficiently precipitated. About 9/10 of the supernatant is preferably taken out of the supernatant and used for filtration. Prior to filtration, the supernatant is diluted with water or a mixed solvent of water and an organic solvent (eg, alcohol such as ethanol, isopropyl alcohol, and benzyl alcohol) until a solution viscosity of 5 cps or more and less than 15 cps is obtained. If it is 15 cps or more, the load on the filter and pump in the filtration step described later is increased, and the processing efficiency is inferior. On the other hand, if it is less than 5 cps, the dilution rate becomes large, and the amount of filtration treatment becomes unnecessarily large. The solution viscosity referred to here is a B type viscometer (BL type) No. manufactured by Tokyo Keiki Co., Ltd. It is a value at 25 ° C. when one adapter is used.

  The diluted solution is subjected to microfiltration. The microfiltration process removes oligomer aggregates generated during the standing period and metal components (metal oxides, metal hydroxide crystals, etc.) that are the polymerization catalyst of the copolyester when added. Is done. The filter medium used for the microfiltration has a filtration particle size (initial filtration efficiency: 95%) of 10 μm or less and 0.5 μm or more, preferably 5 μm or less and 1 μm or more as filtration performance. It is more preferable to use a combination of two or more filters having different filtration performance within the range. When the filtration particle size exceeds 10 μm, removal of coarse oligomer aggregates tends to be insufficient. When the filtration performance is less than 0.5 μm, even necessary particle aggregates are removed, and the originally required slipperiness and blocking resistance may be deteriorated. In the case of using a combination of filters having different filtration performances, it is effective to make a filter in order from a filter with a larger filtration particle size. There is no particular limitation on the type of filter medium for finely filtering the coating solution as long as it has the above performance, and examples thereof include a filament type, a felt type, and a mesh type. The material of the filter medium for finely filtering the coating solution is not particularly limited as long as it has the above performance and does not adversely affect the coating solution, and examples thereof include stainless steel, polyethylene, polypropylene, nylon and the like. The liquid temperature of the copolyester solution at the time of filtration is 15 ° C. or more and less than 35 ° C., preferably 20 ° C. or more and less than 35 ° C. Above 35 ° C, the oligomer dissolves and its removal is insufficient, and when it is lower than 15 ° C, the liquid viscosity increases and the filtration efficiency decreases, which is not preferable. The number of times of filtration through the filter is 2 times or more, preferably 5 times or more, and more preferably 20 times or more. There is no upper limit on the number of times of filtration, but considering efficiency, it may be about 50 times at the maximum.

  Then, the filtrate of this copolyester solution is heated to 50 ° C. or higher and lower than 70 ° C., preferably 55 ° C. or higher and lower than 65 ° C., to dissolve small low molecular weight resin components and catalytic metal compounds that are difficult to remove by filtration. . If it is less than 50 degreeC, a low molecular weight thing and a catalyst metal compound cannot fully be dissolved. When the temperature is 70 ° C. or higher, the copolymerized polyester component is likely to be altered. At this time, in order to keep the temperature of the solution uniform, it is preferable to stir as necessary. The heating time is preferably 1 hour or more and less than 3 hours. If it is less than 1 hour, a sufficient effect cannot be obtained. Moreover, since it may change a copolyester resin in 3 hours or more, it is unpreferable.

  Thereafter, the temperature is lowered, and the mixture is allowed to stand to precipitate fine low molecular weight components, and microfiltration is performed again. By this refiltration treatment, the aggregates of low molecular weight components and the catalyst metal compound crystals that have been regenerated are removed. The standing time is preferably 2 to 10 hours, and the temperature during standing is preferably less than 30 ° C. The upper limit of the filter particle size (initial filtration efficiency: 95%) of the filter used for the refiltration treatment is 10 μm, preferably 3 μm, and the lower limit is 0.5 μm, preferably 1 μm. The filtration temperature is a temperature close to the preferred liquid temperature at the time of application, specifically 15 ° C. or more and less than 35 ° C., preferably 20 ° C. or more and less than 35 ° C. Further, the number of times of filtration passing through the filter is 2 times or more, preferably 5 times or more, and more preferably 20 times or more. There is no upper limit on the number of times of filtration, but considering efficiency, it may be about 50 times at the maximum.

  Confirmation that the content of the low molecular weight component of the copolyester resin is reduced can be performed by measuring the haze of the copolyester resin solution subjected to the heat filtration treatment. Specifically, the haze of the copolymerized polyester resin solution is measured with a haze meter (Nippon Denshoku model TNDH2000) using a cell of 10 mm (quartz cell optical path length), and the haze is 5% or less. Therefore, it can be judged that the content of the low molecular weight component is reduced.

  Other means for reducing the low molecular weight component of the copolyester resin include fractionation by liquid chromatography.

  By using a copolyester resin with a low content of low molecular weight components obtained by the purification treatment as exemplified above in the coating step, thermoplasticity with less optical defects defined by the present invention is effectively obtained. A resin film and a film roll are obtained.

(Polyurethane resin)
The polyurethane resin used for the coating layer of the laminated thermoplastic resin film of the present invention is not particularly limited, but it is preferable to use a water-soluble or water-dispersible resin, for example, containing a blocked isocyanate group. Examples of the resin include a heat-reactive water-soluble urethane in which a terminal isocyanate group is blocked with a hydrophilic group (hereinafter also referred to as a block). Examples of the blocking agent for blocking the isocyanate group with a hydrophilic group include phenols, alcohols, lactams, oximes and active methylene compounds containing bisulfites and sulfonic acid groups. The blocked isocyanate group makes the urethane prepolymer hydrophilic or water-soluble. When thermal energy is applied to the polyurethane resin during the drying or heat setting process during film production, the blocking agent deviates from the isocyanate group, so the polyurethane resin is a water-dispersible copolyester mixed with a self-crosslinked stitch. While immobilizing the resin, it also reacts with the terminal groups of the copolymerized polyester resin. The resin under preparation of the coating solution is poor in water resistance because it is hydrophilic, but when the thermal reaction is completed by coating, drying, and heat setting, the hydrophilic group of the urethane resin, that is, the blocking agent is released, so that the water resistance is low. A good coating film is obtained. Among the above blocking agents, bisulfites are most preferable from the viewpoint that the blocking agent is removed from the isocyanate group at the heat treatment temperature and heat treatment time in the film production process, and from the viewpoint of being industrially available.

  The chemical composition of the urethane prepolymer used in the resin includes (1) an organic polyisocyanate having two or more active hydrogen atoms in the molecule, or a molecular weight having at least two active hydrogen atoms in the molecule. 200 to 20,000 compounds, (2) an organic polyisocyanate having two or more isocyanate groups in the molecule, or (3) a chain extender having at least two active hydrogen atoms in the molecule. The resulting compound has a terminal isocyanate group.

  The compound (1) generally known is a compound containing two or more hydroxyl groups, carboxyl groups, amino groups or mercapto groups in the terminal or molecule, and particularly preferred compounds include polyether polyols. , Polyester polyol, polyether ester polyol and the like. Examples of the polyether polyol include compounds obtained by polymerizing alkylene oxides such as ethylene oxide and propylene oxide, styrene oxide, epichlorohydrin, and the like, compounds obtained by random copolymerization or block copolymerization of two or more thereof, or polyhydric alcohols thereof. There are compounds obtained by performing addition polymerization.

  Examples of the polyester polyol and the polyether ester polyol mainly include linear or branched compounds. Polyvalent saturated or unsaturated carboxylic acids such as succinic acid, adipic acid, phthalic acid, maleic anhydride, or anhydrides of these carboxylic acids, ethylene glycol, diethylene glycol, 1,4-butanediol, neopentyl glycol, Condensation with polyvalent saturated or unsaturated alcohols such as 1,6-hexanediol and trimethylolpropane, polyalkylene ether glycols such as relatively low molecular weight polyethylene glycol and polypropylene glycol, or mixtures of these alcohols Can be obtained.

  Furthermore, polyesters obtained from lactones and hydroxy acids are used as polyester polyols, and polyether esters obtained by adding ethylene oxide or propylene oxide or the like to previously produced polyesters are used as polyether ester polyols. You can also

  Examples of the organic polyisocyanate (2) include isomers of toluylene diisocyanate, aromatic diisocyanates such as 4,4-diphenylmethane diisocyanate, aromatic aliphatic diisocyanates such as xylylene diisocyanate, isophorone diisocyanate and 4,4. -Alicyclic diisocyanates such as dicyclohexylmethane diisocyanate, aliphatic diisocyanates such as hexamethylene diisocyanate and 2,2,4-trimethylhexamethylene diisocyanate, or a single or plural addition of these compounds with trimethylolpropane or the like in advance And polyisocyanates that have been prepared.

  Examples of the chain extender having at least two active hydrogens in (3) above include glycols such as ethylene glycol, diethylene glycol, 1,4-butanediol and 1,6-hexanediol; glycerin, trimethylolpropane and pentaerythritol. Polyhydric alcohols such as ethylenediamine, hexamethylenediamine and piperazine; aminoalcohols such as monoethanolamine and diethanolamine; thiodiglycols such as thiodiethylene glycol; or water.

  In order to synthesize a urethane prepolymer, the reaction is usually carried out at a temperature of 150 ° C. or lower, preferably 70 to 120 ° C. for 5 minutes to several hours by a single-stage or multi-stage isocyanate polyaddition method using the chain extender. The molar ratio of isocyanate groups to active hydrogen atoms can be freely selected as long as it is 1 or more, but it is necessary that free isocyanate groups remain in the obtained urethane prepolymer. Furthermore, the content of free isocyanate groups may be 10% by mass or less, but considering the stability of the urethane polymer aqueous solution after being blocked, it is preferably 7% by mass or less.

  The obtained urethane prepolymer is blocked using the blocking agent (preferably bisulfite). The mixture is mixed with an aqueous blocking agent solution, and the reaction is allowed to proceed with good stirring for about 5 minutes to 1 hour. The reaction temperature is preferably 60 ° C. or lower. Thereafter, it is diluted with water to an appropriate concentration to obtain a heat-reactive water-soluble urethane composition. When the composition is used, it is prepared to have an appropriate concentration and viscosity. Usually, when heated to about 80 to 200 ° C., the blocking agent is dissociated and the active isocyanate group is regenerated, so Alternatively, a polyurethane polymer is produced by a polyaddition reaction that occurs between molecules, and it has the property of causing addition to other functional groups.

  As an example of the heat-reactive water-soluble urethane described above, “Elastolon (registered trademark)” manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd. is typically exemplified. Elastolone is an isocyanate group blocked with sodium bisulfite, and is water-soluble because a carbamoylsulfonate group having strong hydrophilicity is present at the molecular end.

  The resin component used for the coating layer of the laminated thermoplastic resin film of the present invention is a copolyester resin from the viewpoint of adhesion to an acrylic resin and various inks used for forming a diffusion layer, a prism lens, and a hard coat layer. And polyurethane resin. What is necessary is just to select the compounding ratio suitably. For example, when a coating liquid is prepared by mixing a copolymer polyester resin and a polyurethane resin used in the present invention, a copolymer polyester resin (referred to as (A)) and a polyurethane resin (referred to as (B)). The solid content mass ratio is preferably (A) :( B) = 70: 30 to 30:70, more preferably 60:40 to 40:60.

  When the solid content mass ratio of the copolyester resin is larger than the above range, the coating layer becomes brittle, and in the processing step after the formation of the acrylate hard coat layer or diffusion layer, adhesion that can withstand high-speed cutting cannot be obtained. There is. If the solid content mass ratio of the copolyester resin is smaller than the above range, the continuous application streak defined by the present invention is likely to occur, and the applicability and adhesion to the thermoplastic resin film as the base material , Blocking resistance is lowered, which is not preferable. In addition, preferable embodiment of a coating liquid is demonstrated in the place of a manufacturing method.

(particle)
By including particles in the coating layer and forming appropriate irregularities on the surface of the coating layer, slipping property, winding property, and scratch resistance are imparted. For this reason, it is not necessary to contain particles in the substrate, and high transparency can be maintained.

  As the particles, particles having a high affinity with the copolymerized polyester resin or the polyurethane resin are preferable, and it is preferable that the affinity for both has a difference that is unevenly distributed in either phase. By making the particles unevenly distributed in one of the phase-separated resins, the particles are gathered appropriately, and excellent blocking resistance can be obtained with the addition of relatively few particles, that is, without significantly increasing haze. .

  The particles to be included in the coating layer include calcium carbonate, calcium phosphate, amorphous silica, crystalline glass filler, kaolin, talc, titanium dioxide, alumina, silica-alumina composite oxide particles, barium sulfate, calcium fluoride, fluorine. Inorganic particles such as lithium fluoride, zeolite, molybdenum sulfide, mica; crosslinked polystyrene particles, crosslinked acrylic resin particles, crosslinked methyl methacrylate particles, benzoguanamine / formaldehyde condensate particles, melamine / formaldehyde condensate particles, polytetrafluoroethylene particles And heat resistant polymer particles.

  Among these particles, particles made of silicon oxide (particularly silica particles) are preferable from the following points. The first advantage is that a highly transparent film is easily obtained because the refractive index is relatively close to the resin component of the coating layer. The second advantage is that the particles tend to be unevenly distributed in the phase-separated polyurethane resin phase, and the polyurethane resin phase has an inherent property that is inferior in blocking resistance of the polyurethane resin phase present on the surface of the coating layer. It is a point that can be complemented. This is presumably because the surface energy of the particles and the polyurethane resin is close to that of the copolymer polyester resin, and the affinity is high.

  The shape of the particles is not particularly limited, but particles that are close to spherical are preferable from the viewpoint of imparting easy slipperiness.

  The content of the particles in the coating layer is preferably 20% by mass or less, more preferably 15% by mass or less, and particularly preferably 10% by mass or less with respect to the coating layer. When the content of the particles in the coating layer exceeds 20% by mass, the transparency is deteriorated and the film adhesion tends to be insufficient. On the other hand, the lower limit of the content of the particles is preferably 0.1% by mass, more preferably 1% by mass, and particularly preferably 3% by mass with respect to the coating layer.

  Moreover, you may contain 2 or more types of particle | grains from which an average particle diameter differs in a coating layer. Moreover, you may contain the same kind of particle | grains from which an average particle diameter differs. In any case, the average particle diameter and the total content of the particles may be within the above ranges.

  Further, the average particle size of the particles is usually preferably 20 to 150 nm, more preferably 40 to 60 nm. When the average particle size is less than 20 nm, it is difficult to obtain sufficient blocking resistance, and scratch resistance tends to deteriorate. On the other hand, if the average particle diameter of the particles exceeds 150 nm, the haze increases and the particles easily fall off.

  However, in the present invention, sufficient blocking resistance and scratch resistance may not be obtained with only the particles P1 having an average particle diameter of 20 to 150 nm. Therefore, in order to further improve the blocking resistance and scratch resistance, it is preferable to use a small amount of particles P2 having a larger average particle diameter. The average particle size of the particles P2 having a large average particle size is preferably 160 to 1000 nm, particularly preferably 200 to 800 nm. When the average particle size of the particles P2 is less than 160 nm, scratch resistance, slipperiness, and winding properties may be deteriorated. On the other hand, when the average particle size of the particles P2 exceeds 1000 nm, the haze tends to increase. The particles P2 are preferably aggregate particles in which primary particles are aggregated. In this case, the average particle size is considered as the average particle size of the aggregate particles. In this case, the ratio of the average particle size of the aggregate particles to the average particle size of the primary particles is preferably 4 or more from the viewpoint of scratch resistance.

  When using two kinds of particles, for example, the content ratio (P1 / P2) of the particles P1 (average particle size: 20 to 150 nm) and the particles P2 (average particle size: 160 to 1000 nm) in the coating layer is set to 5 to 30. And content of particle | grains P2 shall be 0.1-1 mass% with respect to solid content of a coating layer. Controlling the content of the two kinds of particles having specific particle sizes within the above range optimizes the three-dimensional center plane average surface roughness of the coating layer surface, and achieves both transparency, handling properties and blocking resistance. It is suitable. When the content of the particles P2 exceeds 1% by mass with respect to the coating layer, the haze tends to increase remarkably.

The average particle diameter of the particles is measured by the following method.
Take a photograph of the particles with an electron microscope, measure the maximum diameter of 300-500 particles at a magnification such that the size of one smallest particle is 2-5 mm, and use the average value as the average particle size. . Moreover, when calculating | requiring the average particle diameter of the particle | grains in the coating layer of a laminated film, the cross section of a laminated film is image | photographed by 120,000 times using a transmission electron microscope (TEM), and it exists in the cross section of a coating layer. The maximum diameter of the particles can be determined. When the particle P2 is an aggregate particle, the average particle size is obtained by photographing 300 to 500 cross sections of the coating layer of the laminated film using an optical microscope at a magnification of 200 times, and determining the maximum diameter of the aggregate particles. taking measurement.

(Coating layer)
The coating layer of the laminated thermoplastic resin film of the present invention contains a copolymerized polyester resin and a polyurethane resin as main resin components. The copolyester resin alone has sufficient adhesion to the polyester substrate film, but is inferior to adhesion to the acrylic resin used for prism lenses and hard coats. Further, since it is a relatively brittle resin, it tends to cause cohesive failure with respect to impact during cutting. On the other hand, the polyurethane resin alone is relatively excellent in adhesion to the hard coat layer, the diffusion layer, and the acrylic resin, but is inferior in adhesion to the polyester base film and inferior in blocking resistance. Therefore, it is necessary to contain a large amount or a large particle size or to increase the content of the particle. As a result, since the haze of the film increases, it is not preferable as a substrate film for an optical functional film or an optical functional sheet that has a particularly strong demand for transparency.

And a coating layer has polyester phase A (henceforth abbreviated as PEs phase) which has copolymer polyester-type resin as a main component, and polyurethane phase B (henceforth, PU phase) which has polyurethane-type resin as a main component. (It may be abbreviated as “.”) Having a structure of microphase separation or nanophase separation. When the scanning probe microscope is observed in the phase measurement mode, the area ratio (PEs surface area) of the polyester phase A (indicating a dark hue in the phase image) on the surface of the coating layer defined by the following equation (1): The ratio is 35% or more and less than 90% in a measurement area of 5 μm × 5 μm.
PEs surface fraction (%) = (Area of polyester phase A / Measurement area) × 100 (1)

The PEs surface fraction on the surface of the coating layer has the following technical significance.
When the PEs surface fraction is less than 35%, the surface fraction of the phase mainly composed of polyurethane-based resin on the surface of the coating layer becomes relatively large, and the frequency with which blocking resistance decreases is increased. On the other hand, when the PEs surface fraction is 90% or more, the frequency of decrease in adhesion increases, and in particular, the decrease in adhesion to a solventless hard coat agent becomes significant.

  The lower limit of the PEs surface fraction on the surface of the coating layer is preferably 40%, more preferably 45%, and particularly preferably 50% from the viewpoint of blocking resistance. On the other hand, the upper limit of the PEs surface fraction is preferably 85%, more preferably 80%, and particularly preferably 75% from the viewpoint of adhesion to the functional layer made of an acrylic resin.

  In the present invention, the phase separation structure on the surface of the coating layer was evaluated using a phase measurement mode (phase mode) using a scanning probe microscope (SPM). The phase mode is a phase lag measurement mode that is performed simultaneously with surface morphology observation in a normal dynamic force mode (DFM mode; when SII NanoTechnology SPM is used).

The measurement principle regarding the evaluation of the phase separation structure of the coating layer by the phase measurement mode (phase mode) of the scanning probe microscope (SPM) will be briefly described.
In the phase mode, the phase delay of the cantilever vibration when the DFM operation is performed is detected. In the DFM operation, the shape is measured by controlling the distance between the probe and the sample so that the vibration amplitude of the resonated cantilever is constant. Here, when the signal that vibrates the bimorph (piezoelectric element) for vibrating the cantilever is called an “input signal”, in the phase measurement mode, the phase delay of the effective cantilever vibration signal with respect to this “input signal” Is detected simultaneously with the vibration amplitude. The phase delay responds sensitively to the influence of surface properties, and the softer the sample surface, the greater the delay. By imaging the magnitude of this phase lag, it becomes possible to observe the distribution of surface physical properties (referred to as phase image or phase image). Therefore, when a plurality of resin phases having different physical properties exist on the surface, the phase separation structure can be evaluated by this measurement method.

  However, the evaluation of the phase separation structure of the coating layer may be performed in other modes such as the friction force measurement mode and the viscoelasticity measurement mode in addition to the phase measurement mode as long as it is a surface property distribution evaluation mode by a scanning probe microscope. It is important to select an observation mode that can evaluate the phase separation structure with high sensitivity. In the phase measurement mode, not only the phase lag due to the difference in viscoelasticity of the coating layer but also the phase lag due to the difference in surface physical properties such as the magnitude of the adsorption force can be detected.

  The phase separation structure of the coating layer in the present invention corresponds to a microphase separation structure or a nanophase separation structure in terms of size. When the PEs phase is regarded as a continuous structure having a major axis and a minor axis, the PEs phase is mainly a continuous structure having a width in the minor axis direction of at most 1 μm and a length in the major axis direction exceeding 1 μm. That is, the area of the portion having the continuous structure is 80% or more, preferably 85% or more, more preferably 90% or more with respect to the entire area of the PEs phase. Moreover, even if the PEs phase is dispersed in an island shape that does not correspond to the continuous structure described in the above definition, the end of the coating layer having a continuous structure appears on the surface. is there.

  The size of the continuous structure of the PEs phase is preferably 1 μm at the maximum in the minor axis direction, more preferably 0.8 μm, still more preferably 0.6 μm, and particularly preferably 0.4 μm. It is. The width in the minor axis direction is not particularly limited as to the lower limit, but in order to maintain a continuous structure, the narrowest portion is preferably 0.01 μm, and particularly preferably 0.05 μm. On the other hand, the size of the continuous structure of the PEs phase is preferably such that the length in the major axis direction exceeds 1 μm, more preferably 1.5 μm or more, further preferably 2.0 μm or more, and particularly preferably 2.5 μm or more. It is.

  As can be seen from the representative example shown in FIG. 1, the phase separation structure of the coating layer in the present invention shows a complicated structure that is not found in nature, and it is difficult to uniquely define the phase separation form. The phase separation structure can also be expressed in many ways as follows.

  For example, when the form of the phase-separated structure is expressed as a pattern, it is described in the literature as “dendritic structure” (“Chemical Dictionary”, page 226, June 15, 1979, Sankyo Publishing) Issued by Co., Ltd.), “Rippled structure” (“Pattern”, pages 168-169, issued by Nobara Inc., 2002.0.1), and “Camouflage tone”.

  Further, the phase separation structure on the surface of the coating layer in the present invention is similar to what is expressed as a co-continuous structure in the field of morphology in the polymer blend system. Furthermore, it can also be expressed as a mutual network intrusion structure formed by entanglement of the copolyester resin and the self-crosslinking polyurethane resin.

  In terms of form, the self-similarity of the PEs phase can also be quantitatively expressed using the fractal dimension. For example, as shown in FIG. 3, the surface of the coating layer is observed in a phase measurement mode of a scanning probe microscope, and a phase image in which the outline of the interface between a light hue (polyester phase A) and a dark hue (polyurethane phase B) is emphasized. Can be expressed quantitatively using the fractal dimension obtained from the interface contour using the box counting method as an index indicating the complexity of the boundary line (interface contour) between light and dark hues. it can.

  When the fractal dimension in the unit area is 1, it means a straight line (one dimension), and 2 means a solid surface (two dimensions). That is, the closer the fractal dimension is to 2, the denser the structure. On the other hand, a fractal dimension closer to 1 means a sparse structure.

  Specifically, in the phase image in which the outline of the interface between the light hue (polyester phase A) and the dark hue (polyurethane phase B) is emphasized, the fractal dimension of the boundary line (interface outline) between the light hue and the dark hue is It is preferable that it is 1.60-1.95 in the measurement area of 5 micrometers x 5 micrometers. The upper limit of the fractal dimension is more preferably 1.93, and particularly preferably 1.90. On the other hand, the lower limit of the fractal dimension is more preferably 1.65, and particularly preferably 1.70.

  For example, the fractal dimension of the boundary line (interface contour) between the light hue (polyester phase A) and the dark hue (polyurethane phase B) on the surface of the coating layer shown in FIG. 4 is 1.89. 4 emphasizes the outline of the interface between the light hue and the dark hue in the phase image of FIG. 1 showing a typical phase separation structure on the surface of the coating layer in the present invention, and the boundary line between the light hue and the dark hue. FIG.

  In the present invention, it is important that the coating layer has a microphase separation structure or a nanophase separation structure in order to maximize the functions of the copolyester resin and polyurethane resin used as the raw material of the coating layer. It is. This is because when the two resins are completely compatible, the properties of the two resins cancel each other, and the excellent properties of the copolyester resin or polyurethane resin cannot be expected as a whole. In the coating layer of the present invention, other phase separation structures that can be taken by the PEs phase and the PU phase include those in which the PU phase is dispersed in the PEs phase, and so-called composite forms in which the PEs phase is dispersed in the PU phase. It is also possible to adopt a typical sea-island structure. Of course, this sea-island structure is in an incompatible state of the resin, and if one resin phase is increased, the other is inevitably reduced to form a so-called island. Also in the present invention, if the production conditions are controlled, it is possible to form a coating layer composed of a separated phase having such a sea-island structure. When the effect of the present invention is expected by this sea-island structure, it is necessary to examine the structure further.

  However, considering the non-uniform size of the resin phase that forms the island structure and the non-uniform distribution state, the influence of the shape, number, and distribution state of the island phase cannot be ignored. There is also a concern that the properties of the resin constituting the material may be greatly affected. In this case, it is considered advantageous to maintain the uniformity of the material by adopting a phase separation structure in which the PEs phase and the PU phase of the present invention are intertwined with each other. A phase separation structure that adopts a sea-island structure of PEs phase and PU phase can be mentioned as one of the typical embodiments of the present invention.

  In addition, a core / shell structure can be adopted as still another phase separation structure of the coating layer in the present invention. For example, the PEs phase is surrounded by a PU phase, which is further surrounded by a PEs phase. However, in order to form such a core / shell structure, a very high degree of control is required. Also, because of its core / shell structure, it does not seem to be expected to show excellent material behavior. Furthermore, as a mode of the phase separation structure, a laminated structure in which PEs phases and PU phases are regularly arranged alternately can be adopted. However, it is ideal that the phases are arranged in parallel at substantially equal intervals. However, if the phase width is increased, it becomes difficult to uniformly distribute the PEs phase and the PU phase at the interface of the coating layer. This may affect the quality of the laminated thermoplastic resin film. Due to the subtle disposition of the manufacturing conditions, they may be a mixed type while taking the form of a sea-island structure, a core-shell structure, and a laminated structure. However, it is important for maintaining the quality that the PEs phase and the PU phase have a certain size in the coating layer and that they are uniformly and uniformly mixed.

  A polyester phase A mainly composed of a copolyester resin and a polyurethane phase B mainly composed of a polyurethane resin have irregular shapes. And those resin phases form a complicated arrangement | sequence structure arrange | positioned on the base material which consists of a thermoplastic resin film irregularly and densely and uniformly. Moreover, the structure which the other resin phase digged into the surface of one resin phase in the state of incompatibility may be sufficient. In FIG. 3, the black portion indicates the polyester phase A and the white portion indicates the polyurethane phase B.

  In the case where two types of resin phases are uniformly arranged with respect to a unit area (for example, 5 × 5 μm), if the size of one resin phase is increased, the size of the other resin phase is restricted. Therefore, a large bias occurs in the presence of the resin phase. As a result, it becomes difficult to maintain a state in which both resin phases are separated and uniformly dispersed and unevenness occurs in the material of the coating layer, which is not preferable for quality control.

  In order to cause both resin phases to phase-separate and to be present in the coating layer in a uniformly mixed state, the PEs phase has a maximum width of 1 μm in the minor axis direction and a length in the major axis direction of 1 μm or more. It is preferable. Of course, when there is no high demand for quality, a structure having a relatively large width of about 6 μm at the maximum in the minor axis direction is also possible. The phase separation structure of this continuous phase (PEs phase) includes the resin composition of the coating liquid used for forming the coating layer, the type and concentration of the surfactant, the coating amount, the drying conditions of the coating layer, and the heat setting conditions. By selectively adopting and controlling them, it can be expressed as a microphase separation structure or a nanophase separation structure specific to the coating layer. In any case, the aspect of the phase separation structure of the polyester phase A and the polyurethane phase B on the surface of the coating layer shown in FIG. 1 is a typical model for expressing the effect of the laminated thermoplastic resin film of the present invention. .

Further, the importance of the phase separation structure will be described in detail.
The coating layer in the laminated thermoplastic resin film of the present invention is composed of a copolymer polyester component and a polyurethane component as resin components, and a PE phase having a copolymer polyester resin as a main component and a PU phase having a polyurethane resin as a main component. It is important that the phases are separated and at least the PEs phase has a continuous structure. By phase-separating the above two types of resins without mixing them together, it has excellent adhesion to a base film made of a thermoplastic resin film and has a relatively good solvent resistance. Polymerized polyester resin and polyurethane resin with excellent adhesion to many resins such as hard coat layer, diffusion layer, acrylate resin, etc., which are inferior in solvent resistance. This is because the features of the resin can be fully utilized.

  The polyester phase A constituting the coating layer is preferably composed of a copolyester resin alone, but may contain 0.01 to 40% by mass of a polyurethane resin. Further, the polyester phase A may contain particles in an amount of 0.001 to 20% by mass. Further, in the polyester phase A, a surfactant may be attached to or contained in the resin. Similarly, the polyurethane phase B is preferably composed of a polyurethane resin alone, and can contain particles, a surfactant and the like in an amount as described in the copolymer polyester resin. In particular, in the case of particles having a high affinity with the polyurethane-based resin, it is possible to selectively disperse the polyurethane phase B more selectively than the polyester phase A in the process of forming the coating layer.

  In general, in a composition composed of a mixture of a copolyester resin and a polyurethane resin, the chemical supplementary function is usually such that both are chemically uniform materials and complement each other's properties or functions. Often manifests. On the other hand, the coating layer comprising the polyester phase and the polyurethane phase of the present invention, as described above, the polyester phase and the polyurethane phase are physically separated from each other, resulting in a large bias in the presence of the resin phase. The structure in which both resin phases are separated and uniformly dispersed is maintained. The properties of each resin can be achieved through the surface of each resin phase, for example, in a state in which each resin is phase-separated, such as copolyester resin is anti-blocking and polyurethane resin is adhesive. Sharing. In other words, it is the manifestation of a physical supplementary function, and this very function or principle is a new technical matter that is not recognized at all in the prior art.

  The detailed generation mechanism of the phase separation structure of the coating layer in the present invention is not clear. However, the composition ratio of the copolyester resin and polyurethane resin, the ratio of the water and alcohol dispersion medium, the type of surfactant, the impurities in the surfactant, the pH of the aqueous coating solution, the coating amount of the coating solution, etc. Depending on the balance of delicate conditions such as drying and heat setting time, temperature, and wind speed in the material composition and characteristics, the specific microphase separation structure or nanophase separation structure appears in the coating layer. It can be easily understood from the comparison between the example and the comparative example.

  Furthermore, it seems that the reaction start temperature of the isocyanate group of the polyurethane resin also has a subtle effect. The phase separation structure here does not mean that both the so-called PEs phase and PU phase are separated from each other by a physical boundary, but the boundary is in contact without taking a distance. A lot of copolyester is gathered and biased in the phase, and a lot of polyurethane resin is gathered and biased exclusively in the PU phase, and the boundary between the two layers seems to be separated as if it was clearly distinguishable. Should be seen. In the case of the present invention, there is a possibility that the isocyanate group of the polyurethane-based resin reacts at the boundary, indicating a complicated separation structure.

  The laminated thermoplastic resin film of the present invention has a coating layer composed of a PEs phase and a PU phase, for example, a base material composed of a thermoplastic resin film, and a functional layer such as a hard coat layer and a diffusion layer. It plays the role of the interfacial function which acts on both the so-called base material surface and the functional layer surface equally. Then, both the PEs phase and the PU phase have a structure in which both are separated, and the PEs phase has the excellent properties of the copolyester resin originally possessed by both sides of the coating layer (the interface between the base material and the coating layer, the coating layer). And the interface between the functional layer and the functional layer). That is, the PU phase is in a state in which the excellent properties of the inherent polyurethane-based resin are exerted to the maximum on both sides.

  This is because, in the laminated thermoplastic resin film having a coating layer, the surface of the coating layer has a microphase separation structure or a nanophase separation structure composed of a PEs phase and a PU phase. When the resin is exposed, the properties or functions of the copolyester resin are maximized. Similarly, the polyurethane resin of the PU phase is exposed to maximize the properties or functions inherent in the polyurethane resin. It is because it plays. Therefore, if each of the PEs phase and the PU phase on the surface of the coating layer is distributed in a specific range, the properties or functions of both resins can be exhibited to the maximum. This is because of the unique structure of the laminate, it acts rationally at the interface between the substrate and the coating layer and at the interface between the coating layer and the functional layer.

  Furthermore, in the present invention, when particles are contained in the resin composition constituting the PEs phase and the PU phase, for example, silica particles can be unevenly distributed in the PU phase. This is presumed that the surface energy is closer to the silica particles in the PU phase than in the PEs phase. By making the silica particles unevenly distributed in the PU phase, it is possible to improve the blocking resistance, which is a disadvantage of the polyurethane resin, and to reduce the particle content of the entire coating layer, so that transparency is maintained. It is a structure that is useful for performing functions.

  Similarly, it is suggested that if particles having a surface energy closer to that of the copolyester are selected, the particles can be selectively unevenly distributed in the PEs phase. In a method unpredictable from the prior art, in which particles are unevenly distributed in either a phase separation structure composed of a PEs phase or a PU phase, the slipperiness and blocking properties can be highly improved while maintaining transparency. Therefore, the present invention is also meaningful in that the application range of the material design of the micro phase separation structure or the nano phase separation structure can be expanded.

  When used as an optical functional film such as a lens film or a diffusion plate or a base film of an optical functional sheet, the film length is usually at least even if the film thickness is a relatively thick film of 100 μm or more. It is used for the processing process which laminates | stacks a prism layer and a diffusion layer in the form wound up by the roll shape of 1000 m or more, and sometimes 2000 m or more.

  Therefore, when the laminated thermoplastic resin film of the present invention is used as a roll, the area ratio (PEs surface fraction) of the polyester phase A (indicating a dark hue in the phase image) on the surface of the coating layer is determined in the longitudinal direction of the film ( MD), when measured at 100 m intervals, the variation rate of the PEs surface fraction on the surface of the coating layer is preferably 20% or less, more preferably 15% or less. By setting the variation rate of the PEs surface fraction on the surface of the coating layer in the longitudinal direction to 20% or less, a laminated thermoplastic resin film roll having stable adhesion and blocking resistance can be obtained.

In measuring the PEs surface fraction on the surface of the coating layer, the laminated thermoplastic resin film roll is unwound, and one end of a steady region where the film physical properties are stable in the longitudinal direction of the film is When the first end and the other end are the second end, the first measurement is performed within 2 m inside the first end, and the final measurement is performed within 2 m inside the second end. The measurement of the PEs surface fraction on the surface of the coating layer is performed at each measurement point every 100 m from the measurement point, and then the variation rate (MD) of the PEs surface fraction on the surface of the coating layer defined by the following formula calculate.
Fluctuation rate (MD) = ((maximum value of PEs surface fraction−minimum value of PEs surface fraction) / average value of PEs surface fraction) × 100

Also, the laminated thermoplastic resin film roll was unwound, the film was divided into four equal parts in the width direction (TD), and the PEs surface fraction on the surface of the coating layer at the center of each of the four divided films was measured. The variation rate (TD) of the PEs surface fraction on the surface of the coating layer, defined by the following formula, is preferably 20% or less, more preferably 15% or less.
Fluctuation rate (TD) = ((maximum value of PEs surface fraction−minimum value of PEs surface fraction) / average value of PEs surface fraction) × 100
You may perform this measurement with the jumbo roll before slitting the width direction of a film to a small width size.

(Nuclear)
The conditions for the occurrence of repetitive coating streak defects in the present invention have been unknown until now, but the present inventors have changed the height of the film surface having a specific major axis and height as sharply as the peak shape. It has been found that when a plurality of such portions (protruded portions) are arranged within a specific interval, a continuous coating streak defect occurs.

The film surface is ideally a perfect plane, but in reality, when the average height of the film surface is taken, there is a part (convex part) whose height is higher than the average height. To do. Specifically, in many cases, as shown in FIG. 7 and FIG. 8, the convex part is composed of a sharp peak shape and a small and high part spreading like a mountain skirt around the peak shape. The small and high portions that mainly spread like particle aggregates and mountain ridges are mainly composed of resin components. In the present invention, the nucleus refers to a peak shape portion of a convex portion existing on the film surface and having a size satisfying the following formulas 2 and 3.
Formula 2 10 μm ≦ Dd ≦ 35 μm
Formula 3 30 nm ≦ Dt ≦ 5000 nm

  The major axis of the nucleus represented by Dd is the peak width of this sharp peak shape (that is, when the height of one convex portion is viewed from both ends of the convex portion on the basis of the average height of the film surface. , A distance between two points (two inflection points) where the height increases rapidly, and the length is defined as the maximum at the peak shape part of the one convex part. (See FIG. 8). The maximum nucleus height represented by Dt is a value defined by the difference between the maximum nucleus height and the average height of the film surface (see FIG. 8).

  Specifically, the measurement method of Dd and Dt is measured for a laminated thermoplastic resin film using a non-contact three-dimensional shape measuring device (eg, a non-contact three-dimensional shape measuring device TYPE 550 manufactured by Micromap). When this apparatus is used, for example, the surface shape of the field of 1664 × 1248 μm is measured in the wave mode, and the contour line mode data representing the height in pseudo color is displayed (see FIG. 7). At this time, surface correction (quartic function correction) is performed in order to remove surface waviness. The average height in the measurement range is 0 nm (the average height in the measurement range of the visual field is regarded as the average height of the entire film. Considering the smoothness of the entire film, the average in the measurement range of the visual field is sufficient. This is regarded as the average height of the entire film, and the profile curve of the convex portion is displayed by properly aligning the cursor with the convex portion, and the peak width of the nucleus (sharp peak shape portion) in the field of view and 0 nm Measure the peak top distance from the measured average height (At this time, make sure that the peak width and the peak top distance from the average height of 0 nm are the maximum value at the convex part. Hover over) This peak width is Dd, and the distance of the peak top from the average height of 0 nm is Dt (see FIG. 8).

(Bullet-shaped coated muscle defects)
In the present invention, the portion having the above nucleus is referred to as a defect, and in particular, a case in which the defect is connected in a state defined by the following formulas 4 and 5 is referred to as a continuous coating streak defect.
Formula 4 n ≧ 2
Formula 5 t ≧ 10mm
n: Number of nuclei defined by Equation 2 and Equation 3 per mm of continuous-coated-coated-strip defects t: Length of continuous-coated-coated-strain defects

  That is, in a portion having a length of 10 mm or more, a line-like coated streak defect is formed by arranging two or more of the above defects per 1 mm. Here, when counting the number of nuclei in the continuous application stripe defect, the nuclei arranged within a width of 0.5 mm or less in the width direction of the continuous application stripe defect are counted as the same application stripe defect nucleus. This defined continuous streak defect is actually very thin, but it is detected in a dark room using a three-wavelength fluorescent tube under the specific conditions described later and using bromolite in the same environment. A combination of both methods is detected as a muscle. In addition, the continuous coating streaks defined by the present invention includes those having a core portion divided into a plurality of parts. In addition, the continuous coating streak defect defined in the present invention can be detected relatively easily using only bromolite, and particle aggregates present in the coating solution are concentrated on the film and further scattered in a streak shape. The coarse coating streaks are different in size and shape, and the generation mechanism is also different. It is not clear why there are repetitive coated streaks that are easier to detect when using bromlite and repetitive streaks that are easier to detect when using a three-wavelength fluorescent tube. However, it is assumed that the height of the nucleus and the size of the part of the mountain that exists around the nucleus are involved.

In the laminated thermoplastic resin film of the present invention, the number of continuous coated streak defects is 30 / m ² or less. A laminated thermoplastic resin film having such a number of continuous coating streak defects has not been confirmed before the filing of the present application. The smaller the number of continuous coating streaks, the better the optical properties. Therefore, the number is preferably 20 / m ² or less, more preferably 10 / m ² or less, and even more preferably 5 / m ² or less. Most preferably, there are no streak defects (ie 0 / m ² ). Note that the continuous application stripe defects at the same position in the film width direction are counted as one, but when they are separated by 100 mm or more, they are counted as separate continuous application stripe defects.

When used as an optical base film or optical functional sheet such as a lens film or a diffusion plate, the film length is usually at least 1000 m, sometimes 2000 m even for a relatively thick film having a film thickness of 100 μm or more. It is used for the lamination process of a prism layer or a diffusion layer in the above roll form. On the other hand, this continuous application stripe defect does not occur uniformly on the entire surface of the laminated thermoplastic resin film. Therefore, when the laminated thermoplastic resin film of the present invention is used as a roll, with respect to “the number of continuous coating streaks is 30 / m ² or less”, the continuous coating streaks are 100 m in the film roll longitudinal direction. When 10 points are measured at intervals, all of the 10 measurement points may be 30 lines / m ² or less. That is, the maximum number of continuous application streaks in 10 measurement points measured at intervals of 100 m may be 30 / m ² or less, preferably 20 / m ² or less, more preferably 10 / m ² or less, more preferably 5 / m ² or less, and most preferably 0 / m ² .

(Lumped foreign matter)
In conventional laminated thermoplastic resin films, there is an optical defect caused by massive foreign matters with a major axis of 0.3 mm or more, which is small in frequency but cannot be removed only by filtration treatment of the coating liquid for producing the film. The cause of this was unknown. And the component of the massive foreign material was also unknown.

  In general, as a coating method for laminating a coating layer on one or both sides of a base film, a reverse roll coating method, a gravure coating method, a kiss coating method, a roll brush method, a spray coating method, an air knife coating method, a wire bar Examples include a coating method, a doctor blade method, an impregnation / coating method, and a curtain coating method. Among them, a smooth coating surface is easily obtained with a uniform coating layer thickness, and a reverse roll coating method suitable for functional coating, The gravure coating method, the kiss coating method, and the doctor method are frequently used particularly for applications that require high grades such as optical base films. In these coating methods, a doctor blade 17 is installed, for example, as shown in FIG. 9 in order to scrape off the excess coating solution on the roll or substrate film. In such an apparatus, the inventors of the present invention have a large diameter of 0.3 mm or more as described above, and the cause of the occurrence of optical defects with a low occurrence frequency is the doctor of the coating apparatus for manufacturing the film. The blade mainly contains resin components (particularly low molecular weight components of copolymer polyester resins) and particles contained in the coating liquid, and in some cases, solids containing metal components accumulate, and these solids are constant. When the amount of deposits reached the above, it came off from the doctor blade and thought that this adhered to the substrate film via the coater roll or directly, and at the same time, the mass of foreign particles was also conceived. And this invention reduces the precipitation to the doctor blade of the resin component which was unavoidable conventionally only by filtration processing by performing advanced refining processing about a copolyester resin, and, as a result, occurrence frequency is small. Has achieved a reduction in optical defects that can be significant optical defects.

  Therefore, no matter how high-precision filtration treatment is performed on the coating liquid within a practical range, only the filtration treatment can cause the doctor blade 17 of the coater to form a solid material mainly composed of resin components and particles of the coating liquid. Precipitation could not be reduced. It has also been found that the frequency of occurrence increases particularly when the resin component contained in the coating solution contains a large amount of low molecular weight components.

  Therefore, it is essential that the bulky foreign material referred to in the present invention is mainly composed of a coating layer resin component and particles. Thereby, it is distinguished from impurities removed by filtration processing such as dust, and massive foreign substances mainly composed of aggregates of particles.

  The coating layer resin component, which is the main component of the bulk foreign matter, refers to the copolymer polyester resin and polyurethane resin used in the above coating layer, and in particular, refers to the low molecular weight component of the copolymer polyester resin. Say. A particle means the particle | grains used for said coating layer. In addition, the bulk foreign matter referred to in the present invention is composed of a coating layer resin component and particles, but in some cases, as other components, a metal component such as a metal oxide or metal hydroxide generated from a copolymerization polyester polymerization catalyst. Etc.

  The major axis of the massive foreign material is 0.3 mm or more. Here, the major axis is the maximum when taking the cross-section of the massive foreign matter and measuring the distance between any two points on the outer periphery of the sectional surface of the massive foreign matter. The distance between two points.

The laminated thermoplastic resin film of the present invention contains 30/100 m ² or less of massive foreign substances having a major axis of 0.3 mm or more and mainly composed of a coating layer resin component and particles, and preferably 20 of the massive foreign substances. The number / 100 m ² or less, more preferably 10/100 m ² or less. Most preferably, the massive foreign matter is not present at all in the film.

When the laminated thermoplastic resin film of the present invention is used for an optical base film such as a lens film or a diffusion plate, it is usually at least 1000 m, sometimes 2000 m even in a relatively thick film having a film thickness of 100 μm or more. The roll of the above film length is used for the lamination | stacking process of a prism layer or a diffusion layer. Therefore, in the present invention, considering that the film roll is long, when the roll length of the film roll exceeds 1500 m, “the foreign substance mainly composed of the coating layer resin component and the particles is 30/100 m. For “contains ² or less”, the film of 100 m in the longitudinal direction of the film roll is removed from the portion where the coating layer is finally formed (the portion where the coating solution for forming the coating layer is finally applied), and thereafter 100 m ^In the case where 7 points are measured every ² points, the maximum number of foreign matters having a major axis of 0.3 mm or more whose main component is a coating layer resin component and particles among the 7 points may be 30/100 m ² or less. In the coating process for forming the coating layer, solids mainly containing resin components and particles contained in the coating liquid accumulate on the doctor blade as time passes. This is because it is likely to occur.

(Haze)
In the present invention, the haze means an average value of values obtained by measuring at three different places on the film using a haze meter.
When the haze of the laminated thermoplastic resin film of the present invention is 1.5% or less, it is important when it is used as a base film for an optical functional film or a sheet highly required for transparency. The haze is more preferably 1% or less. When the haze exceeds 1.5%, when the film is used for a lens film for LCD, a base film for backlight, or the like, the sharpness of the screen is lowered, which is not preferable.

  In order to make the haze of the laminated thermoplastic resin film of the present invention 1.5% or less, it is preferable not to contain particles in the base film. When particles are not included in the base film, scratch resistance, handling property when winding in roll form, and handling property when unwinding (sliding property, running property, blocking property, air escape of accompanying air during winding) In order to improve properties, etc., it is preferable that a specific amount of particles having an appropriate size is contained in the coating layer to form appropriate irregularities on the surface of the coating layer.

  In the present invention, the coating layer is provided with a catalyst (inorganic substance, salt, organic substance, alkaline substance, acidic substance, metal-containing organic compound, etc.), antistatic agent, ultraviolet absorber, plasticizer, as long as the effects of the present invention are not hindered. Various additives such as agents, pigments, organic fillers and moist particles may be contained.

  When the laminated thermoplastic resin film of the present invention is used for a substrate for an optical functional film or an optical functional sheet, the three-dimensional center plane average surface roughness (SRa) of the surface of the coating layer of the film is 0.00. It is preferably as smooth as 002 to 0.01 μm. The upper limit of SRa is more preferably 0.008 μm and particularly preferably 0.006 μm from the viewpoint of transparency. On the other hand, the lower limit of SRa is more preferably 0.0025 μm, particularly preferably 0.0030 μm, from the viewpoints of handling properties such as slipping and winding properties, and scratch resistance. A smooth surface having an SRa of less than 0.002 μm is not preferable because blocking resistance, handling properties such as slipping and winding properties, and scratch resistance are reduced. On the other hand, if the SRa of the coating layer exceeds 0.01 μm, haze increases and transparency deteriorates, which is not preferable as an optical functional film or a base film for a sheet.

  Although the film thickness of the laminated thermoplastic resin film of this invention is suitably determined by a use, 30.2-300.2 micrometers is preferable, More preferably, it is 50.2-250.2 micrometers. If the film thickness is less than 30.2 μm, the rigidity becomes insufficient, which is not preferable. On the other hand, when the film thickness exceeds 300.2 μm, there is a high possibility that foreign matter that is an optical defect present in the film increases, and the cost increases.

The thickness of the coating layer is preferably 0.005 to 0.2 μm, more preferably 0.008 to 0.15 μm. The thickness of the coating layer can be measured by cutting the cross section of the coating layer with a microtome and observing with an electron microscope. However, when the coating layer is soft, it may be deformed during cutting. For simplicity, if the coating amount is known, the thickness can be converted from the density of the coating layer. For example, when the density of the coating layer is 1 g / cm ³ , the thickness corresponds to 1 μm if the coating amount is 1 g / m ² . For the density of the coating layer, the thickness of the coating layer is estimated by calculating the density of each material from the type of resin and particles constituting the coating layer, multiplying the density of each material by the mass ratio of the material, and obtaining the sum. be able to.

  When the laminated thermoplastic resin film of the present invention is used as a roll, the winding length and width are appropriately determined depending on the use of the film roll. The winding length of the film roll is preferably 1500 m or more, more preferably 1800 m or more. The upper limit of the winding length is preferably 5000 m. Moreover, it is preferable that the width | variety of a film roll is 0.5 m or more, More preferably, it is 0.8 m. The upper limit of the film roll width is preferably 2.0 m.

  In the case of a roll, the laminated thermoplastic resin film is usually wound around a winding core, but there is no particular limitation on the diameter and material of the winding core, and usually 3 inches, 6 inches, and 8 are generally used. Paper cores such as inches and cores made of plastic or metal can be used.

  The laminated thermoplastic resin film of the present invention has excellent adhesion and blocking resistance, and is characterized by very few continuous bullet-like streak defects. According to a known method, a hard coat film It can be used as an optical functional film such as an antireflection (AR) film, a light diffusion sheet, a prism lens sheet, a transparent conductive film, an infrared absorption film, an electromagnetic wave absorption film, or a base film of an optical functional sheet. . In particular, a film obtained by laminating a functional layer mainly composed of an acrylic resin according to a known method on one side of the laminated thermoplastic resin film of the present invention is useful.

  The laminated thermoplastic resin film of the present invention can also be used as a printing film that is printed using UV ink containing an acrylic resin as a resin component. In this case, as the thermoplastic resin film used as the substrate, an opaque film can be used in addition to the transparent film.

In the present invention, the adhesion means that a solvent-diluted photocurable acrylic hard coat layer is formed on the surface of the laminated thermoplastic resin film, and each of them is a cross-cut peel test (100 cells) using an adhesive tape. ) Is repeated 10 times, which means the adhesion at the interface between the acrylic hard coat layer and the coating layer of the laminated thermoplastic resin film. In the present invention, the adhesiveness defined by the following formula is 80% or more. Preferably it is 85% or more, particularly preferably 90% or more.
Adhesiveness (%) = (1-number of cells peeled off / 100) × 100

Further, the blocking resistance means that the coating layer surfaces of two film samples are overlapped, and a pressure of 1 kgf / cm ² is adhered thereto in an atmosphere of 50 ° C. and 60% RH for 24 hours, and then peeled. If the peeled state is “there is no transfer of the coating layer and it can be peeled lightly”, the result is acceptable.

(Production method)
The method for producing the laminated thermoplastic resin film of the present invention is not particularly limited. For example, one side of a thermoplastic resin film that travels a coating liquid containing a copolymerized polyester resin, a polyurethane resin, particles, and a surfactant is used. Or a coating step for coating on both sides, a drying step for drying the coating layer, a stretching step for stretching in at least a uniaxial direction, and a heat-fixing processing step for heat-fixing the stretched coating film, and the following (1) It is manufactured by a method for manufacturing a laminated thermoplastic resin film that satisfies the conditions (7) to (7).
(1) A nonionic surfactant or a cationic surfactant is blended in an amount of 0.01 to 0.18% by mass with respect to the coating solution.
(2) The mixing ratio of the copolymerized polyester resin and the polyurethane resin is 30 by mass ratio.
70-70: 30.
(3) The applicator roll and the kiss length of the film during coating are 1 mm or more and less than 5 mm.
(4) The final coating amount of the coating layer is 0.005 to 0.2 g / m ² .
(5) The passage time of the film from immediately after application of the coating solution to the entrance of the drying step is less than 2 seconds.
(6) In the drying step, the drying temperature is 120 to 150 ° C., the drying time is 0.1 to 5 seconds, and the wind speed of the drying air is 30 m / second or more.
(7) A first heat setting zone in which the heat setting treatment step is continuously divided into a plurality of heat setting zones, and each zone is partitioned so that the temperature can be controlled independently, and the film passes through. The temperature of the heat setting zone set to the highest temperature is 210 to 240 ° C., and the outlet of the heat setting zone set to the highest temperature from the outlet of the first heat setting zone ( When there are a plurality of films, the passage time of the film to the exit of the heat setting zone closest to the entrance side) is within 10 seconds.
(8) The copolyester resin is a solution of the copolyester resin filtered through a filter having a filtration particle size of 0.5 μm or more and 10 μm or less under a liquid temperature of 15 ° C. or more and less than 35 ° C., and 50 ° C. As described above, after heating to less than 70 ° C., it is further obtained by filtration through a filter having a filtration particle size of 0.5 μm or more and 10 μm or less under conditions of 15 ° C. or more and less than 35 ° C.

In the present invention, the coating layer has the following three morphological and structural characteristics.
(A) Microphase separation or nanophase separation into a polyester phase and a polyurethane phase, and the polyester phase has a specific area ratio (PEs surface fraction).
(B) The composition ratio of the resin component of the coating layer can be changed between the surface and the inside.
(C) The particles may be unevenly distributed in the polyester phase or the polyurethane phase.

  In order to form such a coating layer, the above conditions (1) to (2) and the conditions (4) to (7) are important in the above production method.

  The formation process of the phase separation structure of the water-dispersed copolyester component and the hydrophilic polyurethane component in the present invention is estimated as follows. Both resin components mixed with a common solvent are in a state of being uniformly dispersed or dissolved in the coating solution. After the coating on the PET film, the coated surface after the drying process is in a uniform state without a clear phase separation structure. Thereafter, the phase separation structure is developed by heat treatment in the stretching step and the heat setting treatment step. That is, it is separated into a phase mainly composed of copolymer polyester and a phase mainly composed of polyurethane. Further, as the phase separation progresses, the surface presence ratio of the copolyester component having a lower surface energy is considered to increase.

  In particular, in the present invention, the polyester phase mainly comprising the copolyester resin in the coating layer preferably has a continuous structure having a maximum width of 1 μm and a length exceeding 1 μm, more preferably a copolyester phase. And the polyurethane phase have a co-continuous structure. Within the range of the PEs surface fraction defined in the present invention, the polyester phase mainly composed of a copolyester resin has a fine continuous structure with a maximum width of 1 μm and a length exceeding 1 μm. Visually uniform adhesion can be obtained.

  In a polyester phase composed mainly of a copolyester resin, the phase separation structure where the width exceeds 1 μm at the maximum is locally applied to a functional layer such as a hard coat layer, a diffusion layer, or a prism layer. , A place with poor adhesion occurs. If a portion having poor adhesion exists on the surface of the coating layer, it may lead to macroscopic peeling starting from that portion. In order to achieve a fine continuous structure with a maximum width of 1 μm in the polyester phase, it is important to appropriately select the time and heat setting conditions required to reach the maximum temperature in the heat setting zone from the transverse stretching zone. is there. In particular, when the time required from the transverse stretching zone to the zone where the maximum temperature is reached in the heat setting zone is too long, the phase separation of the coating layer proceeds excessively, resulting in a polyester phase mainly composed of a copolyester resin. In other words, the locations where the width is less than 1 μm are scattered at the narrowest portion. Specific heat setting conditions for producing the laminated thermoplastic resin film of the present invention will be described later.

  In order to control the final phase separation structure on the surface of the coating layer, the solvent evaporation rate in the drying step described later and the subsequent heat treatment are extremely important. By controlling the solvent evaporation rate in the drying process, the composition ratio of the polyester component and the polyurethane component on the surface of the coating layer can be changed.

  For example, when a mixed solvent of water / isopropyl alcohol is used, the ratio of water increases in the solvent remaining on the surface in the late drying process under weak drying conditions. Therefore, the ratio in which the polyurethane-based resin having relatively high hydrophilicity is present on the surface of the coating layer is higher than when the coating layer is dried under strong conditions. Also, changing the coating amount has the same effect as controlling the solvent evaporation rate. That is, when the coating amount is increased, drying takes time, and the remaining solvent existing on the coating surface immediately before drying increases the ratio of water. That is, the ratio of the polyurethane component on the surface can be made higher than when the coating amount is small.

  In the stretching step and the heat setting treatment step, the phase separation of the polyester component and the polyurethane component proceeds, but when either one of the thermal crosslinking starts, the mobility of each phase is greatly reduced, and the progress of the phase separation is suppressed. . That is, the phase separation structure can be controlled by controlling the heating conditions in the stretching process and the heat setting process.

  As described above, the surface phase separation structure and the existence ratio of each phase are strictly controlled by controlling the surface ratio of polyester / polyurethane in the drying process and controlling the progress of phase separation in the stretching process and heat setting process. Is possible. Further, by controlling the surface energy of the particles to be contained in the coating layer, the particles are selectively dispersed in either the polyester phase mainly comprising a copolyester resin or the polyurethane phase mainly comprising a polyurethane resin. be able to.

  In addition, as a result of earnest research on the cause of the occurrence of the continuous coating streak defect defined in the present invention, the continuous coating streak defect has an aggregate of 10 to 35 μm mainly composed of particles as shown in FIG. As shown in FIG. 7, there is a continuous defect in the longitudinal direction of the film, as shown in FIG. The frequency of the occurrence of continuous coating streaks is the composition of the coating solution, the coating conditions such as the kiss length of the coating kiss part, the coating amount, and the elapsed time from coating to the entrance of the drying furnace. It was found that drying conditions such as the wind speed during drying and the like (that is, the above conditions (1) to (6)) are greatly involved. Therefore, it is thought that the aggregate which becomes a factor of a continuous application | coating streak defect is produced | generated in the liquid pool (20 of FIG. 10) which arises in the applicator roll and the coating kiss part of a base film at the time of application | coating. First, the aggregates form nuclei by agglomerating the particles in the above-described liquid pool, and the resin component having a high affinity with the particles covers the periphery of the nuclei, which further forms an aggregate having a diameter of about 20 to 1000 μm. However, it is considered that this aggregate has a certain size or more, and while it is shaved, it adheres to the traveling film and causes a continuous coating streak defect. For this reason, even if the coating solution uses a fine filter and is subjected to precise filtration, the continuous optical defects defined by the present invention cannot be reduced. On the other hand, if the coating solution is filtered with an extremely fine filter of 0.5 μm or less, even the necessary particle aggregates are removed, and the originally required slipperiness and blocking resistance may be reduced.

  Therefore, in order to reduce the repetitive coating streak defect referred to in the present invention, it is not possible to reduce the coarse aggregates of particles that can be optical defects in the coating solution only by microfiltration or the like (rather In order to maintain good slipperiness and blocking resistance, an appropriate particle aggregate is necessary.) It is important to suppress the formation of the aggregate in the liquid reservoir.

  In general, it is known from experience that coating streaks can be reduced to some extent by reducing the shear force of the coating liquid on the roll by reducing the amount of pressing of the roll against the film in the roll coater method, Although it is also effective to some extent in the continuous coating streaks referred to in the present invention, it has not been possible to sufficiently satisfy the level required in recent years only by reducing the pressing amount between the roll and the film. That is, the continuous application streak defect referred to in the present invention cannot be satisfactorily reduced only by the microfiltration treatment of the coating solution and the reduction of the shearing force applied to the coating solution.

  However, according to the manufacturing method, the present invention is achieved by combining the coating solution composition, the coating conditions, and the drying conditions in a highly combined manner with the extremely thin continuous coating streaks that cannot be improved only by the filtration treatment of the coating liquid. It is possible to achieve a significant reduction in the extremely thin repetitive coating streaks that are defined, and the laminated thermoplastic resin film obtained has excellent optical properties.

  Then, the production of a laminated thermoplastic resin film having excellent adhesion and less optical defects defined by the present invention is usually performed by simply filtering the coating solution prepared for forming the coating layer, It cannot be achieved only by reducing aggregates and foreign matters in the liquid, but it is achieved for the first time by preliminarily purifying the copolyester resin, which is a raw material, when preparing a coating liquid.

Hereafter, the said manufacturing method is demonstrated concretely.
(Coating process)
The coating process is preferably carried out by an in-line coating method applied during the production process of the film. For example, the above-mentioned copolymer polyester or the above-mentioned copolymer polyester system is applied to one side or both sides of a traveling substrate thermoplastic resin film. A resin component containing a resin and the polyurethane-based resin, and a coating solution containing the particles are continuously applied. It is more preferable to apply to the base film before the crystal orientation is completed. Examples of the coating method include a reverse roll coating method, a gravure coating method, a kiss coating method, and an offset coating method, and these methods can be performed alone or in combination. These coating methods have a mechanism for scraping off excess coating liquid on the roll with a doctor blade, and are suitable for obtaining a uniform coated surface with few coating spots. In the present invention, it is preferable to use a reverse kiss roll coating method from the viewpoint of surface quality.
In the present invention, the coating solution for forming the coating layer can be prepared according to a known method, but an aqueous coating solution is preferable from the viewpoint of environment and safety. Therefore, the copolyester resin and polyurethane resin used in the present invention are preferably water-soluble or water-dispersible.

  The coating solution is prepared by dispersing or dissolving the resin in a solvent while stirring, then adding particles, surfactants and various additives as necessary, and diluting to a desired solid content concentration. .

  When preparing the coating liquid containing the copolymerized polyester resin (A) and the polyurethane resin (B), the mass ratio of the resin (A) and the resin (B) based on the solid content is (A) / (B) = 70/30 to 30/70 are preferable, and the range of 60/40 to 40/60 is particularly preferable. (Condition (2)) In the present invention, as the resin constituting the coating layer, a third resin other than the copolyester resin and the polyurethane resin can be used in combination. Moreover, you may use a crosslinking agent together.

  In the present invention, the PEs surface fraction on the surface of the coating layer and the PEs mass ratio in the resin component of the coating layer do not correspond as shown in FIG. FIG. 6 clearly shows that even if the PEs mass ratio in the resin component of the coating layer is 50%, the PEs surface fraction on the surface of the coating layer varies from 30 to 91%. This suggests that the composition ratio of the copolyester resin and the polyurethane resin is different between the surface and the inside of the coating layer. That is, in the present invention, it means that the constituent ratio of the copolyester resin and the polyurethane resin can be arbitrarily controlled in the thickness direction of the coating layer.

  In addition, the hardness index of the coating layer surface is set to 3.0 to 15.0 nm by setting the ratio of the copolyester resin (A) and the polyurethane resin (B) in the coating layer within the above range. Can do. When the hardness index of the coating layer surface is less than 3.0 nm, the coating layer becomes brittle. Therefore, after forming a functional layer such as a hard coat layer, a diffusion layer, a prism layer, etc. containing acrylic resin as a constituent component, it is sufficient for the shearing force during high-speed cutting in the processing step of high-speed cutting to a predetermined size. Adhesion is difficult to obtain. Also. When the hardness index of the coating layer surface exceeds 15.0 nm, the blocking resistance tends to be lowered. Furthermore, there exists a tendency for the applicability | paintability to a base film, adhesiveness, and solvent resistance to become inadequate.

  In the present invention, the solvent used in the coating solution includes not only a solution for dissolving the resin but also a dispersion medium used for dispersing the resin in the form of particles, and various solvents such as an organic solvent and an aqueous solvent. From the above viewpoint, an aqueous solvent is preferable.

  The solvent used for the coating solution is preferably a solvent obtained by mixing water and alcohols such as ethanol, isopropyl alcohol, and benzyl alcohol in a range of 30 to 50% by mass in the total coating solution. Moreover, when the mixing amount of alcohol is less than 10 mass%, you may mix in the range which can dissolve organic solvents other than alcohol. However, the total amount of alcohols and other organic solvents in the coating solution is less than 50% by mass. If the mixing amount of alcohols (when other organic solvents are used, the total amount of the alcohols and the organic solvent) is less than 50% by mass, the drying property is improved during coating and drying, and the case of water alone There exists an advantage that the external appearance of a coating layer improves compared with. When the addition amount of the organic solvent is 50% by mass or more with respect to the total solvent, the solid matter tends to be deposited on the doctor blade. Further, the evaporation rate of the solvent is increased, and the concentration change of the coating solution is likely to occur during coating. As a result, the viscosity of the coating liquid is increased and the coating property is lowered, which may cause a poor appearance of the coating film. Furthermore, due to the volatilization of the organic solvent, there is a high risk of fire and the like. In addition, when the amount of the organic solvent added is less than 30% by mass with respect to the total solvent, the ratio of water is relatively increased, and the highly hydrophilic polyurethane component is segregated on the surface of the coating layer, and finally the lamination heat obtained. In the plastic resin film, it is difficult to make the PEs surface fraction on the surface of the coating layer within the range specified in the present invention, and air bubbles tend to be mixed into the coating liquid, resulting in streaks on the coating surface. This is not preferable because defects tend to occur and, moreover, continuous coating streak defects defined by the present invention tend to occur. In the present invention, it is preferable that the balance of the mixed solvent concentration is not greatly changed in the coating step.

  In preparing the coating solution, the copolymer polyester resin uses a low content of low molecular weight component, but in order to reduce the content of the low molecular weight component of the copolymer polyester resin, the above method, That is, a copolymerized polyester resin is dissolved in a solvent to form a solution, and the solution is filtered through a filter having a filtration particle size of 0.5 μm or more and 10 μm or less under a liquid temperature of 15 ° C. or higher and lower than 35 ° C., and then 50 After heating at a temperature of not lower than 70 ° C. and lower than 70 ° C., a method of further processing by filtering with a filter having a filtration particle size of 0.5 μm or more and 10 μm or less under conditions of 15 ° C. or more and less than 35 ° C. (Condition (8)) ), And the filtrate obtained may be used as it is for coating solution preparation.

  In order to adjust the pH of the coating solution, an alkaline substance or an acidic substance may be added as a pH adjuster. The pH adjuster is not particularly limited as long as it does not adversely affect the adhesion, blocking resistance, and coating properties, or can be neglected. For example, sodium bicarbonate and sodium carbonate are used to increase the pH. In the case of lowering, acetic acid and the like are mentioned. The preferred pH of the coating solution of the present invention is 5 or more and less than 8. If the pH is less than 5, the copolyester component tends to segregate on the surface of the coating layer, and the PEs surface fraction tends to be larger than the range defined by the present invention, the hard coat layer in the hard coat film and the diffusion layer in the diffusion plate, In some cases, sufficient adhesion to the prism layer in the prism sheet cannot be obtained. If the pH is 8 or more, aggregation is likely to occur depending on the type of particles, and continuous coating streak defects are likely to occur, and haze increases.

  When adding the particles to the liquid being prepared, it is preferable to add the particles to water or an organic solvent in advance as a dispersion having a concentration of 2% by mass or more and less than 25% by mass. When particles are added directly to the liquid being formulated, uniform dispersion becomes difficult. As a result, particle agglomerates become the core, solid matter is deposited on the doctor blade, and the particles have an affinity for the applicator roll. As a result, an aggregate with a high resin component tends to grow, and as a result, an optical defect and a continuous coating streak defect due to massive foreign matter are likely to occur. When preparing a dispersion liquid of particles, it is preferable to sufficiently disperse using a stirrer. Examples of the stirrer include a powder dissolver (TK homojetter M type), and the dispersion conditions are 5000 rpm or more, preferably 10,000 rpm or more, and a stirring time of 30 minutes or more, preferably 60 minutes with respect to 10 kg of the dispersion. That's it. Further, during stirring, it is preferable to stir while cooling so that the liquid temperature does not rise above 30 ° C.

  In order to improve the wettability of the coating solution to the film and to apply the coating solution uniformly, a nonionic surfactant or a cationic surfactant is used (condition (1)). The use of a surfactant is one of the means for controlling the specific PEs surface fraction at the coating layer surface. These types of surfactants are not particularly limited as long as good coatability can be obtained and the surface fraction of PEs specified in the present invention can be obtained. Among the surfactants, a fluorosurfactant is suitable for obtaining good coatability with a small amount of addition. The addition amount of the nonionic surfactant or the cationic surfactant is 0.01 to 0.18% by mass, preferably 0.02 to 0.1% by mass with respect to the coating solution. By setting the addition amount within the range, the PEs surface fraction defined in the present invention can be obtained. Further, if the addition amount is less than 0.01% by mass, good coating properties cannot be obtained, and if it exceeds 0.18% by mass, the particles contained in the coating solution tend to aggregate. The frequency of occurrence of muscle defects and massive foreign bodies increases excessively. Moreover, it leads to the haze rise of the obtained laminated | multilayer film (especially it is a problem as an optical base film). Further, the surfactant component may bleed out and adversely affect the adhesion.

  In addition, when an anionic surfactant is used, compatibility with the above-described copolymerized polyester and polyurethane may be increased, and the phase separation structure defined in the present invention is difficult to obtain. The addition amount of the surfactant can be appropriately selected as long as it does not inhibit the adhesion with a functional layer such as a hard coat layer or a diffusion layer and can provide good coating properties. For example, in the case of a fluorinated surfactant, it is preferably 30 times or less from the critical micelle concentration with respect to pure water. If it exceeds 30 times the critical micelle concentration, the particles contained in the coating solution tend to aggregate, so that the haze of the obtained laminated film increases, and is particularly preferable as a substrate film for an optical functional film or an optical functional sheet. Absent. In addition, the surfactant component may bleed out on the surface of the coating layer and adversely affect the adhesion. On the other hand, good coatability cannot be obtained at a critical micelle concentration or less. Moreover, it becomes difficult to control within the range of the PEs surface fraction defined in the present invention.

  Further, it is preferable to use a purified surfactant for use in the present invention. In general, surfactants on the market often contain a small amount of impurities. In particular, polyethylene glycol as an impurity may inhibit obtaining a good phase separation structure depending on its content. In order to prevent this, it is preferable to use a purified surfactant that has been subjected to a pretreatment to remove impurities from the surfactant.

The pretreatment process for removing impurities is not particularly limited as long as the impurities can be removed without altering the surfactant. For example, the following method is mentioned.
A method in which at least a surfactant and polyethylene glycol are dissolved in an organic solvent that can be dissolved, allowed to stand at a low temperature, the surfactant as a main component is saturated and precipitated, and then filtered to take out the surfactant with improved purity. Is mentioned. In the case of a perfluoroalkylethylene oxide adduct surfactant, the purity of the surfactant is improved by dissolving it in isopropyl alcohol on a hot bath at 30 ° C. and allowing it to stand at 0 ° C. for about 24 hours, and then filtering out the precipitate. An active agent can be obtained.

In order to promote the thermal crosslinking reaction, a catalyst may be added to the coating solution. For example, various chemical substances such as inorganic substances, salts, organic substances, alkaline substances, acidic substances and metal-containing organic compounds are used as the catalyst. Used.
Furthermore, you may mix various additives, such as an antistatic agent, a ultraviolet absorber, a plasticizer, an antibacterial agent, a photo-oxidation catalyst, a pigment, an organic filler, and a moist particle, in a coating liquid as needed.

  The solid concentration in the coating solution is preferably 30% by mass or less, and particularly preferably 10% by mass or less. The lower limit of the solid content concentration is preferably 1% by mass, more preferably 3% by mass, and particularly preferably 5% by mass.

  The coating liquid is preferably subjected to microfiltration in order to uniformly disperse the resin components and particles of the coating liquid and to remove foreign matters such as coarse particle aggregates and dust in the process. The filter medium for finely filtering the coating liquid preferably has a filtration particle size (initial filtration efficiency: 95%) of 25 μm or less, more preferably a filtration performance of 5 μm or less, more preferably a filtration performance of 1 μm or less, and more preferably This method uses a combination of these filters. When the filtration particle size exceeds 25 μm, removal of coarse aggregates tends to be insufficient. Therefore, the coarse aggregate that could not be removed by filtration spreads due to stretching stress in the uniaxial stretching or biaxial stretching process after coating and drying, and is recognized as an aggregate of 100 μm or more, causing an optical defect. However, if the filtration performance is 0.5 μm or less, even the necessary particle agglomerates are removed, and the originally required slipperiness and blocking resistance may be lowered, which is not preferable. Practically, the lower limit of the filter filtration particle size of the coating solution is 0.8 μm, but the frequency of filter clogging is low, easy to maintain slipperiness and blocking resistance, and it is not suitable for the coating solution. It is also suitable not to apply a shearing force as necessary. There is no particular limitation on the type of filter medium for finely filtering the coating solution as long as it has the above performance, and examples thereof include a filament type, a felt type, and a mesh type. The material of the filter medium for finely filtering the coating solution is not particularly limited as long as it has the above performance and does not adversely affect the coating solution, and examples thereof include stainless steel, polyethylene, polypropylene, and nylon.

  The coating layer coating method in the present invention is not particularly limited as long as it is the above-mentioned method, but the applicator roll is formed by a meniscus formed by a coating liquid formed by bringing a base film into contact with the applicator roll in various arrangements such as horizontal or vertical. A method of transferring the above coating liquid to the base film is preferred. Especially in the production of laminated films for optical applications, as shown in FIG. 9, in order to quickly remove the air bubbles contained in the liquid pool, which are generated on the downstream side of the tangent line between the traveling base film and the applicator roll. A method of running the vehicle vertically is preferable. Furthermore, the method of running the base film in the vertical direction is preferable because it is easy to apply both surfaces simultaneously.

In order to explain the manufacturing method in detail, the reverse coating method will be described as an example.
As shown in FIG. 9, the reverse coating method uses an applicator roll 13 and a metering roll 14 that rotate in the reverse direction of the film traveling direction, the applicator roll 13 is brought into contact with the traveling film 12 and the coating liquid is transferred to the film. It is a method of applying.

  In the reverse coating method, the diameter of the roll is preferably 10 to 50 cm for both the applicator roll and the metering roll, and the applicator roll / metering roll diameter ratio is preferably in the range of 0.5 to 2.

  In order to prevent transfer failure due to insufficient supply of the coating liquid to the base film at the time of application and to apply uniformly, a small amount of liquid as shown in FIG. 10 is provided downstream of the tangent line between the traveling film 12 and the applicator roll 13. It is necessary to set application conditions for generating the pool 20. However, in this liquid reservoir 20, when the balance of the mixed solvent concentration, in the specific example of the present invention, the concentration balance of water and isopropyl alcohol is changed, the particles in the coating liquid and the resin component having a high affinity with these particles are aggregated. It becomes easy to form, and as a result, the continuous coating streak defect prescribed by the present invention is likely to occur. Therefore, in the present invention, it is important to reduce the liquid pool as much as possible and to reduce the fluctuation of the mixed solvent concentration balance of the coating liquid.

Furthermore, means for controlling the fluctuation rate (both MD and TD) of the PEs surface fraction of the laminated thermoplastic resin film roll to 20% or less are the composition of the coating liquid, the coating conditions, the drying conditions, and the heat setting conditions. It is important to keep the film forming conditions such as constant when producing the laminated thermoplastic resin film roll of the present invention. However, in particular, the ratio of the mixed solvent used in the coating solution is likely to fluctuate, and it is important to keep the ratio of the mixed solvent constant in order to reduce the fluctuation of the PEs surface fraction in the longitudinal direction of the film roll.
The means for keeping the ratio of the mixed solvent constant is not limited to the following method.

  First, as shown in FIG. 11, the coating solution tank for supplying the coating solution to the coater is divided into a preparation tank 23 and a circulation tank 22 having a smaller capacity than the preparation tank 23, and the circulation tank 22 and the coater are arranged. It is preferable to circulate the coating liquid only between the two. If a circulation tank is not provided, when the amount of liquid in the tank decreases due to consumption of the coating liquid, the number of times the coating liquid circulates between coaters increases, and the solvent balance tends to fluctuate. It is not preferable because coarse aggregates are likely to be generated. On the other hand, increasing the capacity of the circulation tank 22 relative to the capacity of the tray 18 is effective in stabilizing the mixed solvent concentration balance. Specifically, the capacity of the coating liquid tray 18 is set to 1. Sometimes, the ratio of the capacity of the circulation tank 22 is 1:10 or more, preferably 1:50 or more. If the capacity of the circulation tank 22 is smaller than 1:10, the fluctuation of the mixed solvent concentration balance tends to increase, which is not preferable. More preferably, the ratio of the capacity of the circulation tank 22 to the capacity of the blending tank 23 is 1:10 or more, preferably 1:20 or more. At this time, it is preferable to supply the coating liquid from the preparation tank 23 to the circulation tank 22 so that the capacity of the circulation tank 22 is always constant during operation. An important point in the supply of the coating liquid is that a supply amount that allows a gap between the applicator roll 13 and the metering roll 14 to be filled with a sufficient coating liquid is necessary.

  Defoaming is preferably performed in order to prevent the generation of long coating streaks due to bubbles in the coating solution. Defoaming is performed, for example, by means for preventing air from being entrained in the coating liquid as much as possible and means for removing air in the coating liquid present in a minute amount.

  The means for preventing air from being entrained in the coating liquid as much as possible is that the coating liquid scraped off by the doctor blade 17 from the fountain die 15 and the metering roll 14 falls directly onto the tray 18 and air is mixed in by this impact. In order to prevent this, as shown in FIG. 9, a guide plate 16 is installed under the fountain die 15 and the doctor blade 17 so that the coating liquid flows smoothly into the tray 18 along the guide plate 16. Means. Further, the means for removing the air in the coating liquid present in a minute amount is a cooling device (as shown in FIG. 11) that extends upward in the middle of the pipe that supplies the coating liquid from the circulation tank 22 to the fountain die 15. A branch pipe 21 having a not-shown) is provided, and air contained in the coating liquid is removed from the pipe 21. By setting the temperature of the outlet of the branch pipe 21 to 20 ° C. or less, preferably 10 ° C. or less with a cooling device, volatilization of a highly volatile solvent can be suppressed, and the change in the balance of the mixed solvent of the coating solution can be reduced. . The height of the outlet of the branch pipe 21 is preferably at least 10 cm or more from the liquid level of the coating liquid circulation tank 22 in order to prevent the coating liquid from flowing out and to obtain a sufficient cooling effect. Is 20 cm or more. As a liquid degassing method, air may be removed by degassing under reduced pressure, but the present invention is not preferable because the balance of the mixed solvent tends to be lost.

  It is preferable that the temperature of the coating liquid supplied to the fountain die 15 and the surface temperatures of the applicator roll 13 and the metalling roll 14 be 10 ° C. or higher and lower than 30 ° C. When the temperature of the coating solution is 30 ° C. or higher, the coating solution is easily deteriorated, which is not preferable. If it is less than 10 degreeC, the viscosity of a coating liquid will become high and it will occur easily. Moreover, it is preferable for obtaining uniform quality that the difference of each temperature does not become larger than 10 degreeC. In addition, when the surface temperature of the applicator roll 13 and the metering roll 14, particularly the surface temperature of the metalling roll 14 is 30 ° C. or higher, the roll surface is easily dried, and as a result, solid matter is deposited on the doctor blade 17. End up.

  When the film 12 comes into contact with the applicator roll 13, a coating liquid reservoir 20 is formed on the contact film surface (the boundary between the coating liquid reservoir and the resin applied to the substrate is clearly observed visually). Although the coating liquid reservoir 20 is called a coating kiss portion, in the present invention, the kiss length means the length of the coating kiss portion in a direction parallel to the running direction of the film. In order to obtain the kiss length, the boundary between the coating liquid reservoir and the resin applied to the substrate is observed as two parallel lines, and the distance between the two boundaries may be measured.

  In general, the kiss length of the base film and the applicator roll at the time of coating is usually set in a range of 5 to 20 mm, and particularly in the case of manufacturing a laminated film for optical use, when it is set to 8 mm or more. There are many. This is because, when the kiss length is less than 5 mm, the contact pressure between the base film and the applicator roll is weak, and the air contained in the coating liquid is likely to foam at the meniscus portion, thereby causing long coating streaks. The reason why the thickness is generally less than 20 mm is that a large number of minute scratches may enter the substrate film due to the contact between the applicator roll and the substrate film, which can be a fatal defect. However, in this invention, the kiss length of the applicator roll 13 and the base film 12 at the time of coating shall be 1 mm or more and less than 5 mm (condition (3)). The reason why the kiss length between the applicator roll 13 and the base film 12 is less than 5 mm is to suppress the generation of scratches due to the contact between the applicator roll 13 and the base film 12 to the maximum. If the kiss length between the applicator roll 13 and the base film 12 is less than 5 mm, coating spots due to air bubbles are likely to occur as described above, but in the present invention, the running direction of the base film 12 during application is vertical. Furthermore, this problem was solved by means described later, and the kiss length could be made less than 5 mm.

  The kiss length is controlled by changing the ratio between the film running speed (F) and the peripheral speed (A) of the applicator roll 13 that rotates in the reverse direction with respect to the film running direction (hereinafter referred to as A / F ratio). In order to keep the kiss length within the above range, the A / F ratio is preferably set to a range of 1.02 or more and less than 1.15, more preferably 1.05 or more, 1 Less than 1. When A / F is less than 1.02, the liquid pool becomes extremely small, and the lubricating action by the coating liquid is reduced, so that scratches due to contact between the base film and the applicator roll are likely to occur. When the ratio is 1.15 or more, the liquid pool becomes large as described above, and as a result, the number of continuous application streaks defined by the present invention increases. Usually, when the A / F ratio is less than 1.15, the liquid pool between the film and the applicator roll becomes small and scratches are likely to occur. Therefore, in the manufacturing method, in order to suppress the generation of the scratches, It is preferable to use a mirror-finished roll that has been subjected to chrome plating and has a surface roughness of 0.1 S or less.

  The film running speed is not particularly limited, but is preferably 10 m / min to 100 m / min, and more preferably 20 m / min to 80 m / min. If it is less than 10 m / min, the productivity is low and the cost is high, and the time from coating to the drying furnace entrance described later tends to be long, and as a result, the continuous coating streak defect defined by the present invention is likely to occur. If it exceeds 100 m / min, bubbles are likely to be mixed into the coating liquid and coating spots are likely to occur, which is not preferable.

  Also, the kiss length can be controlled by adjusting the pressing amount of the roll against the film, and the kiss length becomes 1 mm or more and less than 5 mm after setting the A / F ratio within the above range. A method of setting the pressing amount is preferable.

  At the time of application, since the solid is deposited on the doctor blade 17 when the roll is dried as described above, it is important to prevent the roll from drying, but in order to further suppress the generation of doctor blade residue, The roll to be used is preferably a mirror-finished roll having a hard chrome plating treatment and a surface roughness of 0.3 S or less. This surface roughness is more preferably 0.2S or less, and more preferably 0.1S or less. If it exceeds 0.3S, doctor blade residue is likely to occur.

The lower limit of the contact pressure of the doctor blade 17 to the metering roll 14 is usually 20 gf / cm (0.20 N / cm), preferably 30 gf / cm (0.29 N / cm), and the upper limit is usually 100 gf / cm. (0.98 N / cm), preferably 80 gf / cm (0.78 N / cm). If it is less than 20 gf / cm (0.20 N / cm), the effect of scraping off the coating solution on the metalling roll 14 is insufficient, and as a result, coating spots are likely to occur. Moreover, since it will become easy to precipitate a solid substance on the doctor blade 17 when it exceeds 100 gf / cm (0.98 N / cm), it is unpreferable.
The material of the doctor blade 17 may be a resin such as polyethylene, polyester or polyacetal, or may be made of a metal such as stainless steel or Swedish steel, or a ceramic, but is preferably subjected to a polishing process after slitting and has high straightness.

  Further, by improving the accuracy (roundness and cylindricity) of the roll of the coating apparatus, the contact pressure between the doctor blade 17 and the metering roll 14 in contact with the doctor blade 17 can be stabilized, and the solid matter on the doctor blade 17 can be stabilized. It is effective in reducing precipitation. Moreover, it is effective in reducing the fluctuation of the PEs surface fraction in the longitudinal direction of the film roll.

  The roundness of the applicator roll is expressed by the difference between the radii of two concentric circles by the minimum area method determined by using a recorded roundness measuring instrument as shown in JIS B 0621. It is an indicator. The unit of roundness of the roll is mm. In addition, the cylindricality of the applicator roll can be measured in various measurement planes over the entire length by moving the stand with a measuring instrument on the surface plate in the axial direction and placing the probe on the upper surface of the cylinder. This is an index represented by ½ of the maximum difference in reading at the time of measurement. The unit of cylindricity is mm.

  In the present invention, variation in the thickness of the coating layer in the length direction can be reduced by improving the roll accuracy (roundness and cylindricity). Specifically, the roll accuracy (roundness and cylindricity) is preferably less than 5/1000 mm.

  Further, when applying the coating liquid, the surface finish of each roll of the reverse coater is 0.3 S or less, and the accuracy (roundness and cylindricity) of the applicator roll 13 and the metering roll 14 is less than 5/1000 mm, By setting it to 2/1000 mm or more, fluctuations in the wet coating amount can be suppressed, and variations in the coating film can also be suppressed. Preferably, a coating roll whose accuracy (roundness and cylindricity) of the applicator roll 13 and the metering roll 14 is 3/1000 mm is used.

The final coating amount of the coating layer (the solid mass per unit film area after drying and before stretching) is 0.005 to 0.2 g / m ² (condition (4)), preferably 0.008 to 0. .15 g / m ² . In the prior art, when the coating amount is less than 0.05 g / m ^2, it is difficult to obtain sufficient adhesion. However, since the coating layer has a specific phase separation structure, a laminated film having excellent adhesion to the functional layer and the substrate can be obtained even when the coating amount is less than 0.05 g / m ^2. . However, if the coating amount is less than 0.005 g / m ² , sufficient adhesion cannot be obtained. When the coating amount is less than 0.05 g / m ^2, it is preferable to use particles having an average particle size of 60 nm or less. When the average particle diameter of the particles exceeds 60 nm, the particles easily fall off from the coating layer. When the particles are unevenly distributed in the polyurethane phase, the particles are difficult to fall off if the coating amount is 0.005 g / m ² or more. On the other hand, if it exceeds 0.2 g / m ² , the continuous coating streak defect defined by the present invention is likely to occur, and the polyurethane resin component segregated on the surface of the coating layer increases, resulting in a decrease in blocking resistance. Further, the coating amount when not dried (hereinafter abbreviated as wet coating amount) is preferably ² g / m ² or more and less than 10 g / m ² . In order to obtain the final coating amount of the coating layer required at less than 2 g / m ² (the solid content mass per unit area of the film before drying and before stretching), it is necessary to increase the solid content concentration of the coating solution. At this time, since the viscosity of the coating solution becomes high, streaky coating spots are likely to occur. If it is 10 g / m ² or more, it is easily affected by the drying air in the drying furnace, and coating spots are likely to occur. The film coated with the coating amount of the coating amount is guided to a tenter for orientation and heat setting, and is heated there to form a stable film by a thermal crosslinking reaction, thereby forming a laminated thermoplastic resin film.

  When applying the coating solution, it is preferable to set the cleanness to class 5000 or less in order to prevent defects due to dust adhesion.

  Moreover, it is good to make the film tension at the time of coating into 4000-10000N / original fabric width (original fabric width is 1-2m), and when the film tension is in the said range, the flatness of the film on an industrial scale. (The tension depends on the film thickness, and the relatively thin film is kept flat by applying a lower tension) to prevent local contact between the applicator roll and the substrate film. The effect that the transfer amount becomes uniform in the length direction of the film is obtained. Exceeding 10000 N / raw width is not preferable because the original film is deformed, a portion having high local contact pressure is formed on the applicator roll and the base film, scratches are likely to be generated, and breakage may occur. Even when the width is less than 4000 N / raw film, the flatness of the film at the time of coating becomes insufficient, scratches due to local contact between the applicator roll and the base film are likely to occur, and the meandering of the film may also occur. Furthermore, the transfer amount of the coating liquid becomes non-uniform in the film length direction. Further, since the wet coating amount of the film largely fluctuates, the variation in the coating thickness becomes larger, which is not preferable.

  Moreover, in order to make the fluctuation rate (TD) of the PEs surface fraction in the film roll width direction 20% or less, it is important to reduce the variation in the thickness of the coating layer with respect to the width direction of the film roll. For this purpose, it is effective to improve the planarity in the width direction during coating. Specifically, as a means for improving the flatness of the film at the time of coating, a method of sandwiching both surfaces with a pair of pinch rolls 24 at both ends in the width direction of the film between the coater and the drying furnace is also effective. . By causing the pinch roll to grip both ends of the film, the flatness in the width direction of the film is improved on an industrial scale, and the wet coating amount in the width direction of the film is stabilized. Thereby, the dispersion | variation in the application layer of the width direction of a film roll can be reduced. When the both ends of the film are not gripped with a pinch roll, the wet coating amount in the width direction and the length direction of the film varies greatly, and the variation in the thickness of the coating layer also increases.

  In the present invention, the liquid reservoir 20 generated on the downstream side of the tangent line between the traveling film 12 and the applicator roll 13 is minimized as described above, and the generation of aggregates composed of particles and resin components having high affinity with the particles is suppressed. This makes it possible to significantly reduce the continuous application streak defined by the present invention. However, when water and isopropyl alcohol are used as the mixed solvent, the rate of evaporation of isopropyl alcohol is higher than that of water. The resin component is segregated on the polyester base material interface, the resin component having a high affinity with water and the particles having a high affinity with the resin component are segregated on the surface layer of the coating layer, and as a result, the above-mentioned repetitive defects are easily noticeable. Therefore, in the present invention, in order to further reduce the ultra-thin, repetitive coating streaks that occur slightly, the following measures for stabilizing the mixed solvent concentration balance in the coating solution are taken, and specific drying conditions and heat setting conditions are taken. It is preferable that

  To specifically illustrate the mixed solvent concentration balance measure during coating, the apparatus including the applicator roll 13, the metering roll 14, and the coating liquid tray 18 is provided with a solvent volatilization prevention cover 19 as shown in FIG. It is effective to devise a method for bringing the inside of the prevention cover 19 close to the saturated vapor pressure of isopropyl alcohol. When the film roll length exceeds 1000 m, optical defects due to massive foreign matters tend to increase. However, by providing the solvent volatilization prevention cover 19, even if the roll length exceeds 1000 m, optical defects due to massive foreign matters increase. The tendency can also be suppressed. Although it is difficult to seal completely due to the structure, the stability of the solvent concentration balance of the coating liquid on the applicator roll 13 is greatly improved by reducing the opening. The mixed solvent concentration balance measure is not limited to the above.

(Drying process)
When the coating solution is applied and dried, it is often dried using the preheat zone of the tenter, but in this case, depending on the size of the film forming equipment and the traveling speed, generally from application to the start of drying. This time (the film transit time from immediately after application of the coating solution to the entrance of the drying step) takes at least about 5 seconds when a relatively thick film having a film thickness of 30 μm or more is produced. The balance between water and alcohol as a solvent is lost, and this makes it easy for the highly hydrophilic polyurethane resin component and particles having high affinity for the polyurethane resin component to segregate on the surface of the coating layer. Therefore, in the finally obtained laminated thermoplastic resin film, it becomes difficult to control the PEs surface fraction on the surface of the coating layer to a specific range, and it is easy to generate continuous coating streaks. Therefore, in the present invention, it is important to dry immediately after coating, and it is essential that the passage time of the film from immediately after coating of the coating solution to the entrance of the drying process is less than 2 seconds (condition (5)). . The transit time is preferably less than 1.5 seconds. In order to keep the time from this coating to entering the drying oven to less than 2 seconds, it is necessary to select the film running speed as appropriate, but a drying oven (pre-dryer) dedicated to drying the coating is applied. It is preferable to dispose as close as possible to the exit of the apparatus in the film traveling direction.

  In the drying furnace, it is essential that the temperature of the drying air on the coated surface is 120 ° C. or more and less than 150 ° C., and the wind speed is 30 m / second or more (condition (6)). A preferable drying temperature is 130 ° C. or higher and lower than 150 ° C., and a preferable wind speed is 30 to 40 m / sec. When the drying temperature is less than 120 ° C. or the wind speed is less than 30 m / sec, the drying speed becomes slow, the balance between water and alcohol as the solvent of the coating solution is lost, and the ratio of water is relatively likely to increase. Therefore, a highly hydrophilic polyurethane component is segregated on the surface of the coating layer, and it becomes difficult to obtain the PEs surface fraction defined in the present invention in the finally obtained laminated thermoplastic resin film. Further, when a highly hydrophilic polyurethane component is segregated on the surface of the coating layer, particles having a high affinity with the polyurethane component are also easily segregated on the surface, so that the continuous coating streaks are easily noticeable. When the temperature is 150 ° C. or higher, the base film is crystallized and breaks easily during transverse stretching. It is essential that the drying time be 0.5 to 5 seconds (condition (6)), and preferably 1 to 3 seconds. If it is less than 0.5 seconds, drying of the coating layer becomes insufficient, and when passing through a roll arranged between the drying process and the transverse stretching process, the roll may be contaminated with an insufficiently dried coating surface. . On the other hand, if it exceeds 5 seconds, the base film is crystallized, and breakage tends to occur during transverse stretching.

  After drying at a temperature of 120 ° C. to less than 150 ° C., the film is preferably immediately cooled to near room temperature. When the temperature leaves the drying oven at a high temperature of 100 ° C. or higher and comes into contact with a roll near room temperature, scratches are likely to occur due to shrinkage of the film.

  When the wind speed in the drying furnace is usually 30 m / second or more, drying unevenness is likely to occur due to strong drying air on the undried coated surface in the drying furnace. By exhausting the air volume outside the drying furnace, a wind speed of 30 m / second or more can be achieved. It is also important that the exhaust air flow to the opposite side of the coater to prevent unevenness on the coating surface due to the exhaust air at the coater. In order to prevent dust from entering, it is preferable to use air that has been cleaned using a HEPA filter. The HEPA filter used at this time is preferably a filter having a performance of cutting 95% or more of dust having a nominal filtration accuracy of 0.5 μm or more.

  The drying step is preferably composed of a drying zone divided into so-called 2 to 8 zones in which drying temperature and drying time conditions are sequentially changed. Particularly preferably, a multistage drying apparatus divided into 3 to 6 zones is employed. For example, when the coating solution is applied to one or both sides of a uniaxially oriented thermoplastic resin film and dried in a multistage drying furnace disposed directly above the coater, the following method is suitable.

  For example, when drying is performed in four stages, drying is performed in a drying furnace divided into four drying zones. In the first drying zone, the temperature is 125 to 140 ° C. for 0.1 to 4 seconds, in the second drying zone, the temperature is 55 to 100 ° C. for 0.1 to 4 seconds, and in the third drying zone, the temperature is 35 to 55 ° C. In the fourth drying zone for 0.1 to 4 seconds, a method of drying at a temperature of 25 to 35 ° C. for 0.1 to 4 seconds can be mentioned.

  The numerical range of the drying conditions varies somewhat depending on the solid content concentration of the coating solution, and is not limited to the above typical conditions. Furthermore, when performing hot air drying, it is important that the air volume also changes at each stage.

For example, the following method is suitable.
In the first drying zone, the wind speed of the drying air to 30 to 40 m / sec, the supply air volume of the drying air 100-150 ³ / sec, setting the exhaust air volume to 150 to 200 m ³ / sec. From the second drying zone to the fourth drying zone, the supply air volume is set to 60 to 140 m ³ / sec, and the exhaust air volume is set to 100 to 180 m ³ / sec. In any drying zone, it is set so that the drying air does not flow to the coater side.

  Further, while maintaining the temperature at 120 to 150 ° C., the drying temperature and the total drying time may be appropriately adjusted for 0.1 to 5 seconds, preferably 0.5 to less than 3 seconds. Each step (zone) in the drying process is determined appropriately at the manufacturing site in consideration of various conditions such as the concentration of the dispersion, the coating amount, the traveling speed of the coated traveling film, the temperature of the hot air, the wind speed, and the amount of air. The appropriate value can be determined.

(Stretching process)
After drying, the end of the film is gripped with a clip, and is usually heated to 80 to 180 ° C. (preferably 100 to 140 ° C.) and led to a hot air zone having a wind speed of 10 to 20 m / sec. Stretched to -6 times (preferably 2.5 to 5.0 times). Further, stretching may be performed in another direction.

(Heat setting process)
In the manufacturing method, the transverse stretching step, the heat setting treatment step, and the cooling step are continuously divided into 10 to 30 zones, and each zone is partitioned so that the temperature can be controlled independently, and between the zones. Designed to prevent sudden temperature changes. In particular, a rapid temperature change between adjacent zones can be suppressed by raising the temperature stepwise from the latter half of the transverse stretching zone to the heat setting maximum temperature setting zone. In the present invention, when producing a laminated thermoplastic resin film having a specific phase separation structure on the surface of the coating layer, temperature control is very important particularly in the drying step and the heat setting treatment step. Hereinafter, the embodiment will be described in detail.

  As described above, in the heat setting treatment step of the present invention, the heat treatment condition determines the phase separation state of the coating layer. That is, the maximum temperature in the heat setting process, the time required to reach the maximum temperature, and the time required to reach the maximum temperature in the heat setting process from the temperature at which the phase separation of the coating layer starts to proceed significantly. It is important to set appropriately.

  The temperature in each heat setting zone in the heat setting treatment step is slightly different depending on the type of constituent resin of the thermoplastic resin film of the base material, but a phase separation structure is appropriately formed within a temperature range of 100 to 260 ° C. It should be set as follows. Hereinafter, a case where polyethylene terephthalate, which is a typical thermoplastic resin, is used as a base film will be described as an example.

  The temperature of the first heat setting zone through which the film passes in the heat setting treatment step is 190 to 200 ° C. The maximum temperature in the heat setting treatment step is controlled to 210 to 240 ° C, and preferably the lower limit is 225 ° C and the upper limit is 235 ° C (condition (7)). In general, heat fixing is performed at a relatively high temperature of 210 to 240 ° C. in the initial stage of the heat setting treatment, and the temperature is often gradually decreased to 100 to 200 ° C. in the subsequent stage.

  When the maximum temperature in the heat setting treatment step is less than 210 ° C., it is difficult to form a microphase separation structure or a nanophase separation structure in the coating layer. Therefore, it becomes difficult to obtain sufficient adhesion between the base material and the functional layer, which can withstand the peeling of the interface due to the impact during high-speed cutting, which is required in recent years. Furthermore, the thermal contraction rate of the obtained laminated film becomes large, which is not preferable.

  In addition, when the maximum temperature in the heat setting process exceeds 240 ° C., the PEs surface fraction of the coating layer surface increases, and the hard coat layer, the diffusion layer, the prism layer, and the printed layer printed with the ultraviolet curable ink Etc., the adhesion to the functional layer tends to decrease. Furthermore, since the time required to reach the maximum temperature of the heat setting treatment from the temperature at which the phase separation of the coating layer starts to proceed remarkably increases, the width of the narrowest part of the polyester phase mainly composed of the copolyester resin Will be dotted with locations exceeding 1 μm. As a result, a part having poor adhesion is generated on a functional layer such as a hard coat layer, a diffusion layer, a prism layer, or a printing layer printed with ultraviolet curable ink locally, and macroscopic peeling starts from that part. May lead to.

  In the present invention, the passage time of the film from the outlet of the first heat setting zone to the outlet of the heat setting zone set to the maximum temperature (in the case of plural, the outlet of the heat setting zone closest to the inlet side) Within 10 seconds. The passage time of the film is preferably 3 seconds or more and 9 seconds or less (condition (7)). When the passage time exceeds 10 seconds, the phase separation proceeds excessively, and the thinnest portion of the phase mainly composed of the copolyester resin tends to be dotted with portions having a width exceeding 1 μm. As a result, a portion having poor adhesion to a functional layer such as a hard coat layer, a diffusion layer, a prism layer, or a printing layer printed with UV ink is locally generated, which may lead to macroscopic peeling starting from that portion. is there.

  In the present invention, the temperature at which the phase separation of the coating layer starts to proceed remarkably is estimated to be about 200 ° C. within the range of the coating liquid composition shown in the examples of the present invention. However, the temperature is naturally not limited to this temperature because it varies depending on the resin component of the coating layer.

The heat setting process will be described more specifically.
In general, the transverse stretching process, heat setting process, and cooling process are divided into 10 to 30 zones in the tenter in order to suppress a rapid temperature change in each adjacent zone, and temperature control is independently performed in each zone. Has been made. In particular, in the zone set to the maximum temperature of the heat setting treatment process from the latter half of the transverse stretching zone, the temperature of each zone is increased stepwise with respect to the film advancing direction, and the temperature between each heat setting zone is rapidly increased. It is preferable that no significant temperature change occurs.

  In the present invention, it is important to quickly and uniformly raise the passage time of the film from the temperature setting zone where the phase separation starts to proceed remarkably to the maximum temperature setting zone entrance of the heat setting treatment step. . In order to quickly raise the temperature, a method of increasing the heat transfer efficiency in each heat setting zone, for example, a method of increasing the speed of hot air blown to the film is effective. However, in this method, generally, temperature spots are likely to occur, so if spots occur in the phase separation state of the coating layer, or foreign matters such as oligomers slightly adhering to the inside of the apparatus in the heat setting zone soar, In some cases, the soared foreign matter adheres to the film and leads to optical defects.

  On the other hand, if the wind speed is too low, a sufficient heating rate cannot be obtained. Therefore, in the present invention, the wind speed is preferably set to 10 m / second or more and less than 20 m / second. In order to quickly and uniformly raise the temperature of the laminated film, it is effective to arrange the nozzles for blowing hot air at relatively short intervals of 500 mm or less. In the case where the nozzle spacing for blowing hot air is set to 500 mm or less, for example, when the nozzle spacing is set to 300 mm, 350 mm, or 400 mm, it is disadvantageous for equipment maintenance, but it is important for completing the present invention. . The number of nozzles per zone corresponding to one stage is about 6 to 12, and the number is determined in consideration of the state of the nozzle interval, the amount of ventilation, and the ventilation time. In addition, the wind speed described by this invention means the wind speed in the film surface which faced the hot air blowing nozzle exit, and was measured using the thermal-type anemometer (Nippon Kanomax make, Anemomaster model 6161).

1 shows a preferred embodiment of the heat setting treatment step of the present invention.
The heat setting treatment step is continuously divided into a plurality of heat setting zones, and each zone is partitioned so that the temperature can be controlled independently. The heat setting zone is divided into a process in which 2 to 10 steps of heat setting zones are continuously arranged, preferably 4 to 8 steps, and the temperature control management of the laminated film is performed in the heat setting zone divided into multiple stages. It is preferable to

  For example, in the case of a polyester film having a coating layer, the film is sequentially passed through a heat setting zone divided into six stages as described below, and a heat setting process is performed with a subtle temperature difference at each stage. There is a method of trimming the uncoated portions at both ends. The heat setting treatment temperature is 200 ° C. in the first heat setting zone, 225 ° C. in the second heat setting zone, 230 ° C. in the third heat setting zone, 230 ° C. in the fourth heat setting zone, and in the fifth heat setting zone. 210 ° C., 170 ° C. in the sixth heat setting zone, and 120 ° C. in the seventh heat setting zone. In addition, 3% relaxation treatment is performed in the width direction in the sixth heat fixing zone.

  Said stage corresponds to one heat setting zone. Thus, it is preferable to give a subtle temperature difference to the temperature of the heat setting zone of each stage, that is, to give a temperature difference of about 5 to 40 ° C. The setting of this temperature difference is arbitrarily determined in consideration of various factors such as the running speed of the thermoplastic resin film having the coating layer, the air volume, and the thickness of the coating layer.

  Moreover, the laminated thermoplastic resin film roll of the present invention is produced by rolling the laminated film by a conventional method using a winder or the like. The film roll may be cut into an appropriate width by a slitter or the like.

  Next, although the manufacturing method of the laminated thermoplastic resin film of this invention is demonstrated taking the example of a polyethylene terephthalate (it abbreviates as PET below) base material, it is not limited to this naturally. Moreover, the evaluation of the characteristics in this specification was based on the following method.

(1) PEs surface fraction
(1-1) Evaluation of phase separation structure The phase separation structure of the coating layer is evaluated by using a scanning probe microscope (SII Nanotechnology, SPI3800N system / SPA300) in phase measurement mode (phase mode). went. In the phase image, the larger the phase lag, the brighter the color image, and the smaller the phase lag, the darker the image. A small phase lag means that it is harder or has a relatively smaller adsorption force than the other phases. In the coating layer of the laminated thermoplastic resin film of the present invention, the dark color phase is the polyester phase A and the light color phase is the polyurethane phase B.

  The measurement principle of the phase measurement mode in the scanning probe microscope is described in “1-2. Application (mode) on the website of STS Nanotechnology, Inc. (http://www.siint.com/technology/probe_applications.html). In the PDF file of “1. Phase measurement by SPM” in the Phase column.

  The cantilever used for the measurement was mainly DF3 (spring constant: about 1.6 N / m), and a new one was always used in order to prevent deterioration of sensitivity and resolution due to probe contamination. The scanner used was FS-20A. Further, the observation was performed with a resolution of 512 × 512 pixels or more, and the observation field of view was 5 μm × 5 μm. Measurement parameters such as the amplitude attenuation rate of the cantilever, the scanning speed, and the scanning frequency at the time of measurement were set to conditions under which line scanning was performed and observation was possible with the highest sensitivity and resolution.

  The phase mode image obtained in the above (bitmap format 512 × 512 pixels) is read by image processing software (manufactured by Adobe, Photoshop ver. 7.0) and displayed on the display so that the image size is 205 mm × 205 mm. (See FIG. 1). Next, a black line was drawn at the boundary between the light hue and the dark hue with the pencil tool (line thickness: 3 pixels) of the same software to clarify the boundary between the two phases (see FIG. 2). Furthermore, using the paint tool of the same software, the dark hue was painted in black and the light hue was painted in white (see FIG. 3). At this time, a dark color portion having a size on the screen and having a diameter of 2 mm or less in the light hue was determined to be particles unevenly distributed in the light hue, and was painted white. For example, when silica particles are used, it is confirmed that they are unevenly distributed in a light hue.

(1-2) Measurement of PEs surface fraction
(1-2-1) Image analysis method This binarized image is displayed on the same software with a histogram with luminance (black, white) on the horizontal axis and frequency on the vertical axis. The PEs surface fraction was determined.

(1-2-2) Paper Weight Method The PEs surface fraction can be measured using the paper weight method in addition to the image analysis method. The measurement procedure is as follows.
The phase mode image obtained as described above was stored as a digital image in bitmap format. Next, this image was printed out on A4 quality paper using a printer (Xerox, DocuPrint C830). For the output image (200 mm × 200 mm), the boundary between the light hue and the dark hue in the image was clarified with a 4B pencil in a bright room under 500 lux illumination by visual confirmation. At this time, since the dark hue having a diameter of 0.1 μm or less existing in the bright hue is confirmed to be particles contained in the coating layer unevenly distributed in the bright hue, no boundary line is drawn. , Included in light hue. After that, the boundary line where the light hue and the dark hue are clarified is divided by cutting with a cutter knife, and the mass of the light hue (polyurethane phase B) and dark hue (polyester phase A) paper is measured. The ratio of the mass of the dark hue (polyester phase A) to the total mass of the phase paper was determined in units of% and was used as the PEs surface fraction.

(1-2-3) Fluctuation rate of PEs surface fraction (a) Longitudinal direction of film roll A film roll having a film width of 1 m and a film length of 1000 m obtained in Examples and Comparative Examples of the present invention was unwound, and the film In the longitudinal direction (MD), the area ratio (PEs surface fraction) of the polyester phase A (indicating a dark hue in the phase image) on the surface of the coating layer was measured at the following locations, and PEs on the surface of the coating layer in the longitudinal direction: The variation rate of the surface fraction was determined by the following formula.
Fluctuation rate (MD) = ((maximum value of PEs surface fraction−minimum value of PEs surface fraction) / average value of PEs surface fraction) × 100
The measurement of the PEs surface fraction on the surface of the coating layer is 1 at 2 m or less on the inner side of the first end when one end of the steady region where the film properties are stable is the first end and the other end is the second end. The second measurement is performed at a distance of 2 m or less on the inner side of the second end portion, and at every 100 m from the first measurement point.

(B) Width direction of film roll A film roll having a film width of 1 m and a film length of 1000 m obtained in Examples and Comparative Examples of the present invention was unwound, and the film was 4 in the width direction in the width direction (TD) of the film. Divide equally and measure the area ratio (PEs surface fraction) of the polyester phase A (indicating a dark hue in the phase image) on the surface of the coating layer at each center, and measure the PEs surface fraction of the coating layer surface in the width direction. The fluctuation rate of was calculated by the following formula.
Fluctuation rate (TD) = ((maximum value of PEs surface fraction−minimum value of PEs surface fraction) / average value of PEs surface fraction) × 100

(2) Presence / absence of a portion where the width of the polyester phase A exceeds 1 μm at the minimum In the printed phase mode images at 10 different measurement locations obtained as described above, the polyester phase A containing the copolyester resin as a main component The presence or absence of a portion having a width in the short axis direction that is the narrowest and exceeding 1 μm was examined.

(3) Fractal dimension Phase mode image (bitmap format 512 × 512 pixels) obtained by the phase measurement mode (phase mode) using the above-described scanning probe microscope (manufactured by SII Nano Technology, SPI3800N system / SPA300) ) Is read by image processing software (manufactured by Adobe, Photoshop ver. 7.0) and displayed on the display so that the size of the image becomes 205 mm × 205 mm (see FIG. 1). Next, a black line was drawn at the boundary between the light hue and the dark hue with the pencil tool (line thickness: 3 pixels) of the same software to clarify the boundary between the two phases (see FIG. 2). At this time, a dark color portion having a size of 2 mm or less in the bright hue with a size on the screen was determined to be a particle unevenly distributed in the bright hue, and the operation for drawing the boundary line was not performed on this portion. For example, when silica particles are used, it is confirmed that they are unevenly distributed in a light hue.

  An image with a clear boundary line was saved as a bitmap format image, and a fractal dimension analysis was performed by the box counting method. The obtained fractal dimension value was used as an index indicating the complexity of the phase separation boundary line. For the analysis by the box counting method, software AT-Image ver3.2 was used. Specifically, the saved bitmap image was opened on image analysis software AT-Image ver3.2, and binarization processing by luminance histogram was performed from image extraction on the menu (see FIG. 4). The threshold value for binarization was 8. For the binarized image, the fractal dimension was selected from the image measurement on the menu, and the fractal dimension was obtained. At this time, for the calculation of the fractal dimension by the method of least squares, the counting result of a box having a side length of 6 pixels to 63 pixels was used.

  Fractal dimension analysis by the box counting method is a well-known method, and using other image analysis software or programs for dimension analysis is sufficient as long as the reproducibility of the analysis results is sufficiently obtained, and other similar functions are used. You may use the software which has. Examples of other software include image analysis such as “Fractal Analysis System Version 3.33 made by National Institute of Agricultural Sciences, Livestock Pasture Research Institute”, “PopImaging Ver. 3.40 made by Digital Being Kids”, etc. Software.

(4) Measurement of haze The film sample was measured about three different places using the haze meter (Nippon Denshoku make, NDH2000), and the average value was made into haze.

(5) Adhesiveness with photo-curing acrylic coat layer
(5-1) Adhesion with solvent-diluted photo-curing acrylic coating layer On the coating layer surface of the film sample, 50 parts by mass of hard coating agent (manufactured by Dainichi Seika, Seika Beam EXF01 (B)), 25 parts by mass of toluene, After mixing 25 parts by mass of methyl ethyl ketone and applying a well-stirred coating agent with a wire bar, drying at 70 ° C. for 1 minute to remove the solvent, 200 mJ / cm ² with a high-pressure mercury lamp, irradiation distance 15 cm, traveling speed 5 m / min. Under the conditions, ultraviolet rays were irradiated to obtain a hard coat film having a hard coat layer having a thickness of 3 μm.

A surface opposite to the hard coat layer of the obtained hard coat film was attached to a glass plate having a thickness of 5 mm to which a double-sided tape was attached. Next, 100 grid-like cuts that penetrated the hard coat layer and the coating layer to reach the base film were made using a cutter guide with a gap interval of 2 mm. Next, an adhesive tape (manufactured by Nichiban Co., Ltd., No. 405; 24 mm width) was attached to the cut-like cut surface. The air remaining on the interface at the time of pasting was pushed with an eraser to bring it into close contact, and then the adhesive tape was peeled off vigorously and vertically. Further, a new adhesive tape was applied in the same manner, and it was peeled off in a vertical direction. This adhesive tape peeling operation was repeated a total of 10 times, and the adhesion was visually determined from the following formula. In addition, what is partially peeled within one square is also included in the number of peeled.
Adhesiveness (%) = (1-number of cells peeled off / 100) × 100

(5-2) Adhesion with solvent-free photo-curing acrylic coating layer About 5g of hard coating agent (Seika Beam EXF01 (B), manufactured by Dainichi Seika Co., Ltd.) is placed on a clean 5mm thick glass plate. The film layer was laminated so that the coating layer surface of the film sample was in contact with the hard coat agent, and was pressed from above the film sample so as to stretch the hard coat agent with a manual load rubber roller having a width of 10 cm and a diameter of 4 cm. Next, from the film surface side, the hard coat layer was cured by irradiating ultraviolet rays with a high-pressure mercury lamp under conditions of 500 mJ / cm ² , an irradiation distance of 15 cm, and a running speed of 5 m / min.

Subsequently, the film sample which has a hard-coat layer was peeled off from the glass plate, and the hard-coat film was obtained. The surface opposite to the hard coat layer of the hard coat film was attached to a glass plate having a thickness of 5 mm to which a double-sided tape was attached. Next, 100 grid-like cuts that penetrated the hard coat layer and the coating layer to reach the base film were made using a cutter guide with a gap interval of 2 mm. Next, an adhesive tape (manufactured by Nichiban Co., Ltd., No. 405; 24 mm width) was attached to the cut-like cut surface. The air remaining on the interface at the time of pasting was pushed with an eraser to bring it into close contact, and then the adhesive tape was peeled off vigorously and vertically. Further, a new adhesive tape was applied in the same manner, and it was peeled off in a vertical direction. This adhesive tape peeling operation was repeated a total of 10 times, and the adhesion was visually determined from the following formula. In addition, what was peeled partially even with one square was made into the number which peeled.
Adhesiveness (%) = (1-number of cells peeled off / 100) × 100

(6) Blocking resistance The coating layer surfaces of two film samples were overlapped, and the pressure of 1 kgf / cm ² was adhered to this under an atmosphere of 50 ° C. and 60% RH for 24 hours, and then peeled off. The state was judged according to the following criteria.
○: The coating layer is not transferred and can be peeled lightly. Δ: The peeling sound is generated and the coating layer is partially transferred to the other surface. ×: The two films are fixed and cannot be peeled or peeled. Even if the base polyester film is cleaved

(7) Hardness index of coating layer The coating layer of the film sample was scratched using a surface property measuring instrument (manufactured by Shintoa Chemical Co., HEIDON 14). At this time, a genuine needle having a sapphire with a radius of 75 μm at the tip was used as a scratching needle. The traveling speed of the needle was 150 mm / min, and the load was 5 gf.

  The surface shape of the scratch attached to the coating layer was measured under the following conditions using a three-dimensional non-contact surface shape measuring device (Micromap, Micromap 550), and profile mode data was displayed. A representative example is shown in FIG. From the obtained scratch shape data, an average value of 30 height differences between adjacent convex and concave portions was obtained and used as the hardness index of the coating layer. At this time, protrusions having a height of 30 nm or more were judged to be protrusions caused by particles contained in the coating layer or the thermoplastic resin film, and were excluded. Further, protrusions having a height of 1 nm or less were excluded because of the influence of noise.

(Measurement condition)
-Profile mode: Wave mode-Objective lens: 10x-Resolution: 160 x 160 pixels-Measurement length: 207.1 nm

(8) Method for detecting defect of continuous coated streaks Stripped 10 m from the surface of the product film roll having a width of 1 m of the laminated film obtained in the examples and comparative examples, and subsequently extracted a film having a length of 1 m or more and vertically in a dark room. Hanging in the direction. Next, a non-glossy black cloth is placed on the entire back surface of the film, and from the front surface (coating layer surface) using a three-wavelength daylight white fluorescent lamp (FL20SS EX-N / 18P: manufactured by National Corporation) from about 10 ° to the film surface. Observation was performed from the front of the film while changing the angle of the fluorescent lamp within a range of 45 °, and a coating streak defect with a length of 10 mm or more was detected and marked for an evaluation area of 1 m ² . (Even if the width of the product film roll is less than 1 m, the evaluation area may be 1 m ^2. ) The length of the coating streaks was measured so as not to directly contact the film using a ruler. Further, using bromolite (VIDEO LIGHT VLG301 100V 300W LPL) on the side opposite to the coating layer surface to be evaluated, irradiation was performed in the range of about 10 ° to 45 ° in the same manner as described above, and the bromolite irradiation surface side (anti-coating layer surface side) ) Was observed, and the defects of the applied muscle were extracted and marked. At this time, a dull black cloth was placed on the side opposite to the observer. In addition, although the streak in the same position with respect to the film width direction was counted as one, when it was 100 mm or more away, it was counted as a separate streak.

For the marked application streak defect present portion, the repetitive application streak defect referred to in the present invention and the coarse application streak defect in which the particle aggregates present in the coating solution are densely scattered on the film and the like. In order to distinguish, the surface shape of a 1664 * 1248 micrometer visual field was measured on the following measurement conditions using the non-contact three-dimensional shape measuring apparatus TYPE550 by Micromap.
Measurement conditions: wave mode
Using objective lens 10x 0.5x zoom lens

  Next, in the contour line display mode, an image in which the measurement surface was color-coded according to the height was displayed. At this time, surface correction (quaternary function correction) was performed to remove the waviness of the surface shape. In the contour display mode, the average height in the measurement range is set to 0 nm, the maximum height is set to 100 nm, the minimum height is set to -100 nm, and the protrusions with a height of 100 nm or more are displayed in red. I let you. Subsequently, the cross-sectional profile display mode of the same measurement visual field was displayed. On the cross-sectional movement screen, the cursor was pinched at both ends so as to be along the long direction of the protrusion, and the cursor was moved so as to pass through the maximum height position of the protrusion. On the plot screen, the height scale was adjusted so that the entire protrusion was displayed. On the plot screen, two cursors were placed on both ends of the protrusion, and the size (major axis) of the protrusion was read. Next, one cursor was placed at the highest point of the protrusion and the other cursor was placed at a height of 0 nm (the average height within the measurement range was 0 nm) to obtain the protrusion height. Further, the measurement position is shifted in the extension line direction of the measured muscle (here, the nuclei arranged within a width of 0.5 mm with respect to the width direction of the continuous coating muscle are counted as the nuclei of the same muscle) The measurement was repeated until the measurement length was 10 mm.

As a result of the above measurement, the coating streak defect in which the defects having the nuclei defined by the following formulas 2 and 3 are connected in the state defined by the following formulas 4 and 5 is determined as the continuous coating streak defect, and the film The number per 1 m ² was counted and used as the number of continuous coating streak defects of the film.
Formula 2 10 μm ≦ Dd ≦ 35 μm
Formula 3 100 nm ≦ Dt ≦ 5000 nm
Formula 4 n ≧ 2
Formula 5 t ≧ 10
Dd: major axis length of one nucleus of the continuous defect portion Dt: maximum height of one nucleus of the continuous defect portion n: number of nuclei satisfying Equations 2 and 3 per 1 mm of the continuous coating muscle defect t: Length of striped streaks

Moreover, when evaluating the continuous streaky defects per 1 m ^{2 at} intervals of 100 m along the longitudinal direction of the film, about the laminated polyester film roll obtained in the examples, a portion of 10 m after unwinding, a portion of 100 m, Streaky defects were extracted at 10 locations at intervals of 200 m and 100 m, and the number of continuous coated streaks was counted.
The maximum value among the measured number of continuous application streak defects at 10 locations was the maximum number of continuous application streak defects of the film roll.

(9) Kiss length The length of the coating liquid reservoir (coating kiss part) formed on the contact film surface when the coating film is in contact with the applicator roll, in the direction parallel to the film running direction (longitudinal direction) Measured (unit: mm).

(10) Thickness of the biaxially stretched film The thickness of the biaxially stretched film was measured with a micrometer (ST-022 GAUGESTAND, manufactured by ONO SOKKI) in the length direction of the film roll in accordance with JIS C 2151.
(11) Bulk foreign matter optical defect detection method A sample film roll having a width of 1 m and a length of 100 m taken out from the product film roll obtained in the examples and comparative examples was hung in the vertical direction in a dark room. At this time, the surface layer 100 m of the product film roll was removed, and the subsequent 100 m was used as a sample. Next, a non-glossy black cloth is arranged on the entire back surface of the film, and bromlite (made by VIDEO LIGHT VLG301 100V 300W LPL) is used from the front surface (covering layer surface) to roll out the laminated film to about 10 ° with respect to the film surface. From the front of the film while changing the angle of the bromolite in a range of 45 ° to 45 °, an optical defect having a major axis of 0.3 mm or more for an evaluation area of 100 m ² , a magnifier with a scale of 10 times (SCALE LUPE manufactured by PEAK × 10) and marking was performed (the evaluation area may be 100 m ² even if the width of the product film roll is less than 1 m). Further, using a brush (TZ-4021N manufactured by KOKUYO), the defective part was lightly wiped, and after confirming that it was not attached to dust, the defective part was rubbed using Kimwipe impregnated with methyl ethyl ketone (WIPRS S200: manufactured by Crecia). The number of defects that disappeared was determined and used as the number of defects per 100 m ² (the solvent in this case is not particularly limited as long as it can dissolve the coating layer). Moreover, when measuring 7 points at a length of 100 m in the length direction of the film, after unwinding from a film roll having a winding length of 1500 m or more, the 100 m portion was removed, and a 100 m sample was taken and continuously taken in the same manner. Seven film samples having a length of 100 m were collected, the number of optical defects having a major axis of 0.3 mm or more was counted for each sample, and the maximum number of defects was defined as the maximum number of defects per 100 m ² in a film roll having a winding length of 1500 m. . (Even if the width of the product film roll is less than 1 m, the evaluation area of each sample may be 100 m ² )

Example 1
(1) Preparation of coating solution The coating solution used in the present invention was prepared according to the following method.
A reaction vessel was charged with 95 parts by weight of dimethyl terephthalate, 95 parts by weight of dimethyl isophthalate, 35 parts by weight of ethylene glycol, 145 parts by weight of neopentyl glycol, 0.1 part by weight of zinc acetate and 0.1 part by weight of antimony trioxide. The transesterification was carried out over 3 hours. Next, 6.0 parts by mass of 5-sodium sulfoisophthalic acid was added, and esterification was performed at 240 ° C. over 1 hour, and then at 250 ° C. under reduced pressure (10 to 0.2 mmHg) over 2 hours. A polycondensation reaction was performed to obtain a copolyester resin (A) having a molecular weight of 19,500 and a softening point of 60 ° C. The obtained 30% by mass aqueous dispersion of the copolyester resin (A) was allowed to stand for 10 days, and about 9/10 of the supernatant was taken out and used for coating solution preparation. The aqueous dispersion of this copolyester resin (A) is filtered with a felt type filter having a filtration particle size of 5 μm under the condition of a liquid temperature of 25 ° C. until it is circulated five times (denoted as filtration step 1-1). Further, the mixture was filtered (referred to as filtration step 1-2) with a felt type filter having a filtration particle size of 1 μm until the number of circulation was 30 times. Next, the mixture was heated to 60 ° C. and held for 2 hours, and further filtered under a condition of 25 ° C. with a felt type filter having a filtration particle size of 1 μm until the number of circulation was 5 times (referred to as filtration step 2).

  Self-crosslinking polyurethane resin (B) containing an isocyanate group blocked with 7.5 parts by mass of a 30% by mass aqueous dispersion of the copolyester resin (A) obtained by the above treatment and sodium bisulfite 11.3 parts by mass of a 20% by weight aqueous solution (Daiichi Kogyo Seiyaku Co., Ltd .: trade name ELASTRON (registered trademark) H-3) and 0.3 parts by mass of an elastron catalyst (Daiichi Kogyo Seiyaku Co., Ltd .: trade name Cat64). 39.8 parts by mass of water and 37.4 parts by mass of isopropyl alcohol were mixed, and 10% by mass of a fluorine-based nonionic surfactant (Megafac (registered trademark) F142D: manufactured by Dainippon Ink & Chemicals, Inc.). 0.6 mass part of aqueous solution, 2.3 quality of 20 mass% aqueous dispersion of colloidal silica (manufactured by Nissan Chemical Industries, Snowtex OL; average particle size 40 nm) as particles P1 0.5 parts by mass of an aqueous dispersion of 3.5% by mass of dry process silica (manufactured by Nippon Aerosil Co., Ltd., Aerosil OX50; average particle size 200 nm, average primary particle size 40 nm) was added as an amount of particles P2. When preparing a 3.5% by mass aqueous dispersion of the particles P2, 10 kg of the dispersion was stirred using a powder dissolver (TK homojetter M type) at a rotational speed of 10,000 rpm and a stirring time of 60 minutes. did. Subsequently, the pH of the coating solution was adjusted to 6.2 with a 5% by mass aqueous sodium bicarbonate solution to obtain coating solution A. In addition, the said surfactant used what was pre-processed by the following method.

  Isopropyl alcohol (IPA) was added to the above-mentioned surfactant, and heated and dissolved in a 30 ° C. hot bath to prepare a 15 mass% surfactant IPA solution. This solution was filtered with a quantitative filter paper (Advantech Toyo, No. 5C) to remove insolubles and dust in the solution. After filtering the said solution, this solution was put into the airtight glass container, and it left still for 24 hours in a 0 degreeC freezer. After 24 hours, the solution containing the precipitated solid was subjected to suction filtration using the quantitative filter paper. The solid on the filter paper was vacuum-dried to obtain a solid, diluted with water to a 10% by mass aqueous solution, and used as a pretreated surfactant.

  The surfactant obtained by the pretreatment was analyzed with a TLC-coated plastic sheet (manufactured by Merck, silica gel 60) using methanol as a developing solution. As a result of coloring the sample spot with iodine vapor, it was confirmed that a spot corresponding to polyethylene glycol was not detected.

(2) Manufacture of laminated polyester film After drying polyethylene terephthalate resin pellets having an intrinsic viscosity of 0.62 dl / g containing no particles as a raw material polymer for a base film at 135 ° C. for 6 hours under reduced pressure (133.3 Pa) Then, it was supplied to an extruder, melted and extruded into a sheet at about 285 ° C., and rapidly cooled and solidified on a metal roll maintained at a surface temperature of 20 ° C. to obtain a cast film. At this time, a stainless sintered filter medium having a filtration particle size (initial filtration efficiency: 95%) of 15 μm was used as a filter medium for removing foreign substances from the molten resin. Next, this cast film is heated to 95 ° C. with a heated roll group and an infrared heater, and then stretched 3.5 times in the longitudinal direction with a roll group having a difference in peripheral speed to form a uniaxially oriented PET film (base material). Obtained. Subsequently, the coating liquid A was subjected to microfiltration with a felt type polypropylene filter medium having a filtration particle size (initial filtration efficiency: 95%) (filtration step 3), and then the surface temperature was reduced to 30 ° C. or less by a reverse kiss roll method. It is applied to one side of a uniaxially oriented PET film, and zone No1 temperature is 135 ° C for 1.0 second, zone No2 temperature is 65 ° C for 2.2 seconds, zoned in a four-zone drying furnace placed just above the coater. Drying was performed at a temperature of No. 3 of 40 ° C. for 1.8 seconds and a temperature of No. 4 of 30 ° C. for 1.8 seconds. The coating amount was set to 0.08 g / m ² as the solid content. The time from the application to the entrance of the drying oven at this time was 0.8 seconds. Further, at this time, the wind speed of the drying air in the zone No. 1 is 30 m / sec, the supply air volume of the drying wind is 130 m ³ / sec, the exhaust air volume is 170 m / sec, and the supply air volume of the zone No 2 to the zone No 4 is 100 m ³ / sec. The exhaust air volume was set to 150 m / sec so that the dry air did not flow to the coater side. The film tension was set to 7000 N / raw width (m), and both ends of the film were held with pinch rolls from the coating to the entrance of the drying furnace.

The coating conditions at this time were as follows.
(A) A / F ratio 1.06; the pressing amount is adjusted so as to have the following kiss length (b) applicator roll and film kiss length during coating: 2 mm
(C) Applicator roll and metering roll are both 22 ° C
(D) Temperature of the coating solution supplied to the fountain die: 23 ° C.
(E) Doctor blade contact pressure to the metering roll: 30 gf / cm (0.29 N / cm)
Further, in this coating, a coating apparatus having the following characteristics was used (see FIG. 11).
(A) A coating apparatus in which a solvent volatilization prevention cover 19 is provided on a coating apparatus including the applicator roll 13, the metering roll 14, and the coating liquid tray 18 is used.
(B) Applicator roll 13 diameter φ250 mm, metering roll 14 diameter φ220 mm
(C) Surface roughness of applicator roll 13 and metering roll 14: 0.1S
(D) Roundness of applicator roll and metering roll: 3/1000 mm
(E) Doctor blade: Material SUS402 Thickness 0.075mm, Width 50mm (Miller Graphics, product name Echo Blade)
(F) The ratio of the volume of the coating liquid tray 18 to the volume of the circulation tank 22 = 1:50
(G) Capacity ratio of the tank 22 for circulation and the capacity of the tank 23 for blending = 1: 40
The amount of liquid in the circulation tank 22 was always kept constant.

  Subsequently, the end portion of the film was gripped with a clip, led to a hot air zone having a temperature of 120 ° C. and a wind speed of 15 m / sec, and stretched 4.3 times in the width direction. Next, while maintaining the stretched width, heat setting zone No. 1 (temperature 200 ° C. wind speed), heat setting zone No. 1 2 (temperature 225 ° C.), heat setting zone No. 2 3 and heat setting zone no. 4 (temperature 230 ° C.), heat setting zone No. 4 5 (temperature 210 ° C.), heat fixing zone No. 5 6 (temperature 170 ° C., relaxation of 3% in the width direction), heat setting zone No. 6 7 (Temperature 120 ° C.) was successively passed through, and then the uncoated parts on both ends of the film were trimmed, wound up with a winder, and further divided into 4 parts in the width direction and slit. A laminated polyester film roll having a width of 1 m, a film length of 1500 m, and a film thickness of 125 μm was obtained. The hot air velocity in the heat fixing zone was 15 m / second, the passage time was 4.5 seconds in each zone, the nozzle interval for blowing hot air was 350 mm, and the number of nozzles per zone was 8.

(Example 2)
A laminated polyester film roll having a width of 1 m, a film length of 1500 m, and a thickness of 125 μm was obtained in the same manner as in Example 1 except that the pressing amount was changed and the kiss length of the applicator roll and the film was 4 mm. It was.

(Example 3)
A laminated polyester film having a width of 1 m, a film length of 1500 m, and a thickness of 125 μm in the same manner as in Example 1 except that the A / F ratio was 1.09 and the pressing amount was changed so that the kiss length was 2 mm. Got a roll.

Example 4
The time from coating to the entrance of the drying oven was 0.7 seconds, the drying time was 0.8 seconds, and the passage time of each zone was 3.5 seconds and the film thickness was 100 μm in the heat setting step. A laminated polyester film roll having a width of 1 m and a film length of 1500 m was obtained in the same manner.

(Example 5)
Example 1 except that the time from coating to the entrance of the drying furnace was 1.0 second, the drying time was 1.9 seconds, the passage time of each zone was 6.6 seconds, and the film thickness was 188 μm in the heat setting step. In the same manner as above, a laminated polyester film roll having a width of 1 m and a film length of 1500 m was obtained.

(Example 6)
In Example 1, except that the mass ratio of the copolymerized polyester resin and the polyurethane resin in the coating liquid was changed to the following coating liquid B, which was changed to 60/40, the same method as in Example 1, A laminated polyester film roll having a width of 1 m, a film length of 1500 m, and a thickness of 125 μm was obtained.
(Preparation of coating solution B)
9.0 parts by mass of a 30% by mass aqueous dispersion of the copolyester resin (A) used in Example 1, and 9.0% by mass of a 20% by mass aqueous solution of the polyurethane resin (B) used in Example 1. Part, 0.3 parts by mass of elastolone catalyst (Daiichi Kogyo Seiyaku, Cat64), 40.6 parts by mass of water, and 37.3 parts by mass of isopropyl alcohol were mixed. Furthermore, 0.6 mass parts of the surfactant aqueous solution used in Example 1 and 2.3 mass of a 20 mass% aqueous dispersion of colloidal silica (manufactured by Nissan Chemical Industries, Snowtex OL; average particle size 40 nm) as particles P1. 0.5 parts by mass of a 3.5 mass% aqueous dispersion of dry silica (Aerosil OX50, manufactured by Nippon Aerosil Co., Ltd .; average particle diameter 200 nm, average primary particle diameter 40 nm) is added as mass parts and particles P2, and 5 mass% sodium bicarbonate. The pH was adjusted with an aqueous solution to obtain a coating solution B.

(Example 7)
In Example 1, except that the mass ratio of the copolymerized polyester resin and the polyurethane resin in the coating solution was changed to the following coating solution C changed to 40/60, the same method as in Example 1, A laminated polyester film roll having a width of 1 m, a film length of 1500 m, and a thickness of 125 μm was obtained.
(Preparation of coating liquid C)
6.0 parts by mass of a 30% by mass aqueous dispersion of the copolyester resin (A) used in Example 1 and 13.5% by mass of a 20% by mass aqueous solution of the polyurethane resin (B) used in Example 1 Part, 0.3 parts by mass of elastolone catalyst (Daiichi Kogyo Seiyaku, Cat64), 38.9 parts by mass of water, and 37.5 parts by mass of isopropyl alcohol were mixed. Further, 0.6% by mass of a 10% by mass aqueous solution of the surfactant used in Example 1, and 20% by mass aqueous dispersion of colloidal silica (Nissan Chemical Industries, Snowtex OL; average particle size 40 nm) as particles P1. Of 0.5 mass parts of a 3.5 mass% aqueous dispersion of dry-process silica (manufactured by Nippon Aerosil Co., Ltd., Aerosil OX50; average particle diameter 200 nm, average primary particle diameter 40 nm) as 2.3 parts by mass of particles P2, The pH was adjusted to 6.2 with a 5% by mass aqueous sodium bicarbonate solution to obtain coating solution C.

(Example 8)
A laminated polyester film roll having a width of 1 m, a film length of 1500 m, and a thickness of 125 μm was obtained in the same manner as in Example 1 except that the coating amount was 0.12 g / m ² as the solid content.

Example 9
In the preparation of Example 1, the standing period of the 30% by mass aqueous dispersion of the copolyester resin (A) was changed from 10 days to 5 days to obtain a coating liquid D. A laminated polyester film roll having a width of 1 m, a film length of 1500 m, and a thickness of 125 μm was obtained in the same manner as in Example 1 except that the coating liquid D was used.

(Example 10)
In the preparation of Example 1, the coating solution E was used without performing the filtration treatment (filtration step 1-2) before the heating treatment of the 30% by mass aqueous dispersion of the copolyester resin (A). A laminated polyester film roll having a width of 1 m, a film length of 1500 m, and a thickness of 125 μm was obtained in the same manner as in Example 1 except that the coating liquid E was used.

(Example 11)
In the preparation of Example 1, the filtration accuracy of the filtration treatment (filtration step 2) after the heating treatment of the 30% by mass aqueous dispersion of the copolyester resin (A) was changed from 1 μm to 5 μm, and the coating solution F and did. A laminated polyester film roll having a width of 1 m, a film length of 1500 m, and a thickness of 125 μm was obtained in the same manner as in Example 1 except that the coating solution F was used.

(Example 12)
In the preparation of Example 1, the heating temperature of the 30% by mass aqueous dispersion of the copolyester resin (A) was changed from 60 ° C. to 55 ° C. to obtain a coating solution G. A laminated polyester film roll having a width of 1 m, a film length of 1500 m, and a thickness of 125 μm was obtained in the same manner as in Example 1 except that the coating solution G was used.

(Example 13)
In Example 1, a laminated polyester film was obtained in the same manner as in Example 1 except that a different coating apparatus was used in the following points.
Coating device (A ') Applicator roll, metering roll and coating device including coating liquid pan are not used. Solvent volatilization prevention cover is not used. (D') Capacitance ratio of coating liquid tray and tank for circulation = 1: 50
(In addition to the circulation tank, the preparation tank was not used, and the coating solution was prepared in the circulation tank and re-prepared when the coating solution ran out.)

(Example 14)
A laminated polyester film roll having a width of 1 m, a film length of 1500 m, and a thickness of 125 μm is obtained in the same manner as in Example 1 except that a coating apparatus having a surface roughness of the applicator roll and the metering roll of 0.3 S is used. It was.

(Example 15)
A laminated polyester film roll having a width of 1 m, a film length of 1500 m, and a thickness of 125 μm is obtained in the same manner as in Example 1 except that the applicator roll and the metering roll have a roundness of 6/1000 mm. It was.

(Example 16)
A laminated polyester film roll having a width of 1 m, a film length of 1500 m, and a thickness of 125 μm was obtained in the same manner as in Example 1 except that the contact pressure of the doctor blade to the metering roll was 60 gf / cm (0.59 N / cm). Obtained.

(Example 17)
A laminated polyester film was obtained in the same manner as in Example 1 except that the coating liquid Q in which the polyurethane resin (B) was changed to the following polyurethane resin was used. The polyurethane resin was obtained by the following method.
(Preparation of polyurethane resin)
93 polyester diols (OHV: 111.8 eq / ton, AV: 1.1 eq / ton) having a composition of adipic acid // 1,6-hexanediol / neopentyl glycol (molar ratio: 4 // 3/2) 22 parts by mass of xylylene diisocyanate were mixed and reacted at 95-100 ° C. for 1 hour under a nitrogen stream to obtain a urethane prepolymer (NCO / OH ratio: 1.50, free isocyanate group: theoretical value 3.29). %, Measured value 3.16%).
The resulting urethane prepolymer was then cooled to 60 ° C., added with 4.5 parts by weight of methyl ethyl ketoxime and reacted at 60 ° C. for 50 minutes to contain free isocyanate 1.3% and partially blocked. A urethane prepolymer was obtained. Then, the said urethane prepolymer was cooled to 55 degreeC, the mixed solvent which consists of 9 mass parts of isopropyl alcohol and 140 mass parts of methanol was added, and it mixed uniformly. Next, 9.3 parts by mass of a 50% by mass aqueous sodium bisulfite solution and 5.4 parts by mass of a 30% by mass aqueous solution of N-methyltaurine were added and vigorously stirred. Water solubility began to appear after about 30 minutes, and free sodium bisulfite became almost zero after 2 hours, and the reaction was completed. Water was added thereto to obtain a 20% by mass aqueous solution that was cloudy and viscous.

(Example 18)
In Example 1, a 10% by mass aqueous solution of a fluorine-based cationic surfactant (manufactured by Neos Co., Ltd., Aftergent 310) pretreated by the same method as in Example 1 was used as the surfactant used in the coating solution. A laminated polyester film roll having a width of 1 m, a film length of 1500 m, and a thickness of 125 μm was obtained in the same manner as in Example 1 except that the coating liquid H was changed.

Example 19
In Example 1, a laminated polyester film roll having a width of 1 m, a film length of 1500 m, and a thickness of 125 μm was obtained in the same manner as in Example 1 except that the coating liquid I that was not subjected to the pretreatment of the surfactant was used. Obtained. The phase separation structure between the copolymerized polyester resin and the polyurethane resin by the scanning probe microscope (SPM) on the surface of the coating layer of the obtained laminated polyester film was discernable but could be somewhat unclear.

(Comparative Example 1)
In the preparation of the coating liquid of Example 1, the standing time of the 30% by mass aqueous dispersion of the copolyester resin (A) was 1 day, and the filtration steps 1 and 2 and the heating step were not performed. A coating solution was prepared in the same manner as in Example 1 to obtain a coating solution J.
The dried polyethylene terephthalate resin pellets as in Example 1 were supplied to an extruder, melt-extruded into a sheet at about 285 ° C., and rapidly cooled and solidified on a metal roll maintained at a surface temperature of 30 ° C. to obtain a cast film. It was. At this time, a stainless sintered filter medium having a filtration particle size (initial filtration efficiency: 95%) of 15 μm was used as a filter medium for removing foreign substances from the molten resin. Next, as in Example 1, this cast film was heated to 105 ° C. with a heated roll group and an infrared heater, and then stretched 3.6 times in the longitudinal direction with a roll group having a difference in peripheral speed, and uniaxially oriented PET. A film was obtained.

Subsequently, the coating liquid J is microfiltered with a felt type polypropylene filter medium having a filtration particle size (initial filtration efficiency: 95%) of 10 μm, applied to one side of a uniaxially oriented PET film by a gravure reverse roll method, and then introduced into a drying furnace at a temperature of 120. Dry at 3.2 ° C. for 3.2 seconds. In the application, the following application apparatus and application conditions were used. The coating amount was set to 0.08 g / m ² as the solid content. At this time, the time from coating to the entrance of the drying furnace was 3.2 seconds, the wind speed in the first zone of the drying furnace was 15 m / sec, and the wind speed in the second zone to the fourth zone was the same as in Example 1, and the drying wind The supply air volume of the first zone was 70 m ³ / sec in both the first zone and the fourth zone, and the exhaust air was naturally exhausted before and after the drying furnace.

Coating condition (a ′) A / F ratio 1.20; Adjust the pressing amount to the following kiss length (b ′) Gravure roll and film kiss length during coating: 10 mm
(C ') Gravure roll temperature 22 ° C
(D) Temperature of the coating solution supplied to the fountain die: 23 ° C.
(E) Doctor blade linear pressure: 30 gf / cm (0.29 N / cm)
Coating device (A ") gravure roll and coating device including coating liquid pan are not used. Solvent volatilization prevention cover is not used. (B ') Gravure roll diameter φ250mm
(H) Surface shape of gravure roll: number of lines 300 / inch Line angle 45 degrees (D ') Roundness of gravure roll: 6/1000
(E) Doctor blade: Material SUS402 Thickness 0.075mm, Width 50mm (Miller Graphics, product name Echo Blade)
(F) The ratio of the capacity of the liquid tray to the capacity of the circulation tank = 1: 50
(I) A tank for blending was not used separately from the tank for circulation, and the coating liquid was blended in the circulation tank and re-blended when the coating liquid was exhausted. )

  Then, the edge part of the film was hold | gripped with the clip, and it guide | induced to the hot air zone heated at 120 degreeC, and extended | stretched 3.8 times in the width direction after drying. At this time, the wind speed in the tenter was 15 m / second, and the drying time was 20 seconds. The time from application to the tenter entrance was 10.0 seconds. Next, heat setting and relaxation treatment were performed in the same manner as in Example 1 to obtain a laminated polyester film roll having a width of 1 m, a film length of 1500 m, and a thickness of 125 μm.

(Comparative Example 2)
(1) Preparation of coating liquid K 3.0 parts by mass of 30% by mass aqueous dispersion of copolymerized polyester resin (A) used in Example 1, 20 of polyurethane resin (B) used in Example 1 18.0 parts by mass of a mass% aqueous solution, 0.3 parts by mass of a catalyst for elastron (Daiichi Kogyo Seiyaku, Cat 64), 70.7 parts by mass of water, and 4.7 parts by mass of isopropyl alcohol were mixed. . Furthermore, as a surfactant, 0.6 part by mass of a 10% by mass aqueous solution of dodecylbenzenesulfonic acid, and as a particle A, a 20% by mass aqueous dispersion of colloidal silica (manufactured by Nissan Chemical Industries, Snowtex OL; average particle size 40 nm). 0.5 parts by mass of a 3.5 mass% aqueous dispersion of 2.3 parts by mass of dry silica (Nippon Aerosil, Aerosil OX50; average particle size 200 nm, average primary particle size 40 nm) as particles B, The coating liquid K was used. The pH of the coating liquid K was 4.8 because pH adjustment was not performed. In addition, the standing days of the 30% mass% aqueous dispersion of the copolyester resin (A) were set to 1 day, and the filtration steps 1 and 2 and the heating step were not performed.

(2) Production of laminated polyester film After the polyethylene terephthalate resin pellets containing no particles used in Example 1 and having an intrinsic viscosity of 0.62 dl / g as a raw material polymer at 135 ° C. for 6 hours under reduced pressure (1 Torr), It was supplied to an extruder, melted and extruded into a sheet at about 285 ° C., and rapidly cooled and solidified on a metal roll maintained at a surface temperature of 20 ° C. to obtain a cast film. At this time, a stainless sintered filter medium having a filtration particle size (initial filtration efficiency: 95%) of 15 μm was used as a filter medium for removing foreign substances from the molten resin.

  The obtained cast film was heated to 95 ° C. with a heated roll group and an infrared heater, and then stretched 3.5 times in the longitudinal direction with a roll group having a peripheral speed difference to obtain a uniaxially oriented PET film. Next, the coating solution K was microfiltered with a felt type polypropylene filter medium having a filtration particle size (initial filtration efficiency: 95%) of 10 μm, and applied to one side of a uniaxially oriented PET film by the reverse roll method under the following conditions.

Coating condition (a ″) A / F ratio 1.15; Adjust the pressing amount to the following kiss length (b ′) Applicator roll and film kiss length during coating: 10 mm
(C ") 23 ° C for both applicator roll and metering roll
(D ′) Temperature of coating solution supplied to fountain die: 25 ° C.
Furthermore, in this coating, a coating apparatus different from that in Example 1 was used in the following points.
(A ') Solvent volatilization prevention cover is not used in the applicator including the applicator roll, the metering roll and the coating liquid tray (C') Surface roughness of the applicator roll and the metering roll: 0.3S
(D ″) Roundness of applicator roll and metering roll: 6/1000 mm

Subsequently, while holding the edge of the film with a clip, the film was guided to a hot air zone heated to 80 ° C., and the coated surface was dried and then stretched 4.0 times in the width direction. At this time, the wind speed in the tenter was 15 m / second, and the drying time was 20 seconds. The time from application to the tenter inlet was 10.0 seconds. The coating amount was set to 0.10 g / m ² as the final solid content. Further, the temperature in each heat setting treatment step is 200 ° C. in the first heat setting zone, 210 ° C. in the second heat setting zone, 220 ° C. in the third heat setting zone, 225 ° C. in the fourth heat setting zone, and the fifth heat. The film thickness is the same as in Example 1 except that the fixing zone is 230 ° C., the sixth heat fixing zone is 235 ° C., the seventh heat fixing zone is 240 ° C., and the widthwise relaxation treatment is not performed. A laminated polyester film having a thickness of 125 μm was obtained.
The phase separation structure of the copolymerized polyester resin and the polyurethane resin by a scanning probe microscope (SPM) on the surface of the coating layer of the obtained laminated polyester film could not be observed.

(Comparative Example 3)
A laminated polyester film having a film thickness of 125 μm was obtained in the same manner as in Example 1 except that the time from application to the entrance of the drying furnace was 3.2 seconds.

(Comparative Example 4)
3.0 parts by mass of a 30% by mass aqueous dispersion of the polyester resin (A) obtained in Example 1, 18.0 parts by mass of a 20% by mass aqueous solution of the same polyurethane resin (B) as in Example 1, Catalyst for Elastron (Daiichi Kogyo Seiyaku Co., Ltd .: trade name Cat64) 0.3 parts by mass, 37.3 parts by mass of water and 37.8 parts by mass of isopropyl alcohol were mixed, and the same interface as in Example 1 0.6 parts by mass of an activator aqueous solution, 2.3 parts by mass of a 20% by mass aqueous dispersion of particles P1 (manufactured by Nissan Chemical Industries, Ltd .: Snowtex OL, average particle size 40 nm), and particles P2 (manufactured by Nippon Aerosil Co., Ltd .; Aerosil OX50, an average particle diameter of 500 nm, an average primary particle diameter of 40 nm) of 3.5% by mass aqueous dispersion was added in an amount of 0.5 parts by mass, and the pH was adjusted with a 5% by mass aqueous sodium bicarbonate solution to obtain a coating solution L. Same as Example 1 Thus, a laminated polyester film having a film thickness of 125 μm was obtained.

(Comparative Example 5)
A laminated polyester film having a film thickness of 125 μm was obtained in the same manner as in Example 1 except that the pressing amount was changed and the applicator roll at the time of coating and the kiss length of the film were 20 mm.

(Comparative Example 6)
A laminated polyester film having a film thickness of 125 μm was obtained in the same manner as in Example 1 except that the wind speed in the drying furnace was 15 m / sec.

(Comparative Example 7)
A laminated polyester film having a film thickness of 125 μm was obtained in the same manner as in Example 1 except that the coating amount was 0.22 g / m ² as the solid content.

(Comparative Example 8)
In Example 1, the standing period of the 30% by mass aqueous dispersion of the copolymerized polyester resin (A) was set to 1 day, and the filtration steps 1 and 2 and the heating step were not performed, and the following different points were applied. A laminated polyester film roll having a width of 1 m, a film length of 1500 m, and a thickness of 125 μm was obtained in the same manner as in Example 1 except that the apparatus and method were used.
Coating device (A ') Applicator roll, metering roll, and coating device including coating solution pan are not used for the solvent volatilization prevention cover. (I) The preparation tank is not used separately from the circulation tank. The mixture was prepared in a circulation tank and re-prepared when the coating solution was exhausted.
(J) In the filtration step 3, a felt type filter having a filtration particle size of 3 μm was used.

(Comparative Example 9)
In Comparative Example 8, a laminated polyester film roll having a width of 1 m, a film length of 1500 m, and a thickness of 125 μm was obtained in the same manner as in Example 1 except that the filtration particle size of the felt type filter in the filtration step 3 was changed to 1 μm. It was.

(Comparative Example 10)
In Example 1, the same method as in Example 1 except that the 30% by weight aqueous dispersion of the copolyester resin (A) was not subjected to the heating treatment to obtain the coating solution M, and the width was 1 m and the film length. A laminated polyester film roll having a thickness of 1500 m and a thickness of 125 μm was obtained.

(Comparative Example 11)
In Example 1, a laminated polyester film having a film thickness of 125 μm was obtained in the same manner as in Example 1 except that the coating liquid N prepared without adding a surfactant to the coating liquid was used.

(Comparative Example 12)
In Example 1, the film thickness is the same as in Example 1 except that the coating liquid O prepared so that only the amount of the surfactant in the coating liquid is 0.60% by mass in solid content is used. A laminated polyester film of 125 μm was obtained.

(Comparative Example 13)
In Example 1, the temperature in each heat setting treatment step was 190 ° C. in the first heat setting zone, 195 ° C. in the second heat setting zone, and 200 ° C. in the third heat setting zone to the fifth heat setting zone. Obtained a laminated polyester film having a film thickness of 125 μm in the same manner as in Example 1. The phase separation structure of the copolymerized polyester resin and the polyurethane resin by a scanning probe microscope (SPM) on the surface of the coating layer of the obtained laminated polyester film could not be observed.

  In Examples 1 to 19 and Comparative Examples 1 to 13, the composition and properties of the coating solution are shown in Table 1, the coating and drying conditions are shown in Tables 2 and 3, the heat setting conditions are shown in Table 4, and the film properties and properties are shown in Table 5. Shown in

  The laminated thermoplastic resin film of the present invention is excellent in adhesion to functional layers such as a hard coat layer, a diffusion layer, and an antireflection layer, and is excellent in blocking resistance and transparency, and further has a continuous coating streaks defect and Since there are few optical defects due to massive foreign matters, optical functional films such as hard coat films, antireflection (AR) films, light diffusion sheets, prism lens sheets, transparent conductive films, infrared absorption films, electromagnetic wave absorption films, etc. It is suitable as a base film for an optical functional sheet. Moreover, it can be used also as a film for printing printed using UV ink which uses an acrylic resin as a resin component.

It is explanatory drawing of the phase image which observed the surface of the coating layer in the lamination | stacking thermoplastic resin film of this invention in the phase measurement mode of the scanning probe microscope. In the phase image of FIG. 1, it is explanatory drawing of the phase image which emphasized the outline of the interface of a light hue and a dark hue with image processing software. FIG. 3 is an explanatory diagram of a phase image in which the outline of the interface between the light hue and the dark hue in FIG. 2 is emphasized and the dark hue is filled with image processing software. FIG. 3 is an explanatory diagram illustrating a boundary line between a light hue and a dark hue in the phase image in which the outline of the interface between the light hue and the dark hue in FIG. 2 is emphasized. It is explanatory drawing which shows the height difference of the crack at the time of measuring the surface shape of the crack | wound attached to the surface of the coating layer in the wave mode using a three-dimensional non-contact surface shape measuring apparatus. In an Example and a comparative example, it is explanatory drawing which shows that PEs surface fraction of a coating layer surface and PEs mass ratio in the resin component of a coating layer do not respond | correspond. It is an image obtained by non-contact three-dimensional shape measurement on the surface of the laminated thermoplastic resin film, and is displayed so that unevenness on the film surface can be seen three-dimensionally. The part surrounded by a circle is the nucleus. It is the image which expanded the part with a nucleus in FIG. It is a cross-sectional profile of a part with a nucleus. It is the schematic of the part which performs the application | coating process for manufacturing the laminated thermoplastic resin film of this invention. It is the schematic of the part to which the film and applicator roll which run are the closest. It is the schematic of the production line for manufacturing the laminated thermoplastic resin film of this invention.

Explanation of symbols

1 Dark hue (Polyester phase A mainly composed of copolymer polyester resin)
2 Light hue (Polyurethane phase B mainly composed of polyurethane resin)
3 Particle 4 Line 5 highlighting the outline of the interface between light hue and dark hue 5 Dark hue 1 binarized with luminance histogram 6 Bright hue 2 binarized with luminance histogram 7 Unevenness on the surface of the coating layer Profile curve 8 Scratch valley 9 Scratch top 10 Example 11 Comparative example 12 Base film 13 Applicator roll 14 Metalling roll 15 Fountain die 16 Coating liquid guide plate 17 Doctor blade 18 Coating liquid tray 19 Solvent volatilization prevention cover 20 Reservoir 21 Branching pipe 22 for defoaming Circulation tank 23 Preparation tank 24 Pinch roll 25 Filter

Claims (16)

A laminated thermoplastic resin film having a coating layer containing a resin component and particles containing a copolymerized polyester resin and a polyurethane resin on one or both surfaces of a thermoplastic resin film,
The coating layer has a structure in which a polyester phase A mainly composed of a copolymerized polyester resin and a polyurethane phase B mainly composed of a polyurethane resin are microphase-separated or nanophase-separated, and a scanning probe When the microscope is observed in the phase measurement mode, the area ratio (PEs surface fraction) of the polyester phase A (indicating a dark hue in the phase image) defined by the following formula (1) is 5 μm × A defect having a core defined by the following formulas (2) and (3), which is 35% or more and less than 90% in a measurement area of 5 μm and is present in the laminated film, is represented by the following formulas (4) and (5). The number of continuous coated streak defects that are continuous in a defined state is 30 / m ² or less, and the content of massive foreign matters having a major axis of 0.3 mm or more whose major component is a coating layer resin component and particles. , 30 / 100m ² Laminated thermoplastic resin film which is a lower.
PEs surface fraction (%) = (Area of polyester phase A / Measurement area) × 100 (1)
10 ≦ Dd ≦ 35 (2)
30 ≦ Dt ≦ 5000 (3)
n ≧ 2 (4)
t ≧ 10mm (5)
Dd: Core major axis (μm)
Dt: Maximum height of the nucleus (nm)
n: Number of nuclei defined by the formula (2) and the formula (3) per 1 mm of the continuous applied muscle defect t: Length of the continuous applied muscle defect   The laminated thermoplastic resin film according to claim 1, wherein the resin component containing the copolymerized polyester resin and the polyurethane resin has a mass ratio of the copolymerized polyester resin and the polyurethane resin of 70/30 to 30/70.   The laminated thermoplastic resin film according to claim 1 or 2, wherein the copolyester resin is a copolyester resin having a low content of low molecular weight components.   The copolymerized polyester resin is obtained by filtering a solution of the copolymerized polyester resin with a filter having a filtration particle size of 0.5 μm or more and 10 μm or less under a liquid temperature of 15 ° C. or more and less than 35 ° C. The product according to claim 3, wherein the product is obtained by further filtering after filtering at a temperature of 15 ° C or higher and lower than 35 ° C and filtering with a filter having a filtration particle size of 0.5 µm or more and 10 µm or less. Laminated thermoplastic film.   The surface of the coating layer is observed in the phase measurement mode of a scanning probe microscope, and in the phase image in which the outline of the interface between the light hue and the dark hue is emphasized, the boundary line between the light hue and the dark hue (using the box counting method) The laminated thermoplastic resin film according to any one of claims 1 to 4, wherein a fractal dimension obtained from an outline of the interface is 1.60 to 1.95 in a measurement area of 5 µm × 5 µm.   The laminated thermoplastic resin film according to any one of claims 1 to 5, wherein the particles contained in the coating layer are particles made of silicon oxide.   The laminated thermoplastic resin film according to any one of claims 1 to 6, wherein the thermoplastic resin film base material contains substantially no particles.   The laminated thermoplastic resin film according to any one of claims 1 to 7, wherein particles in the coating layer are unevenly distributed in the polyester phase A or the polyurethane phase B.   The laminated thermoplastic resin film according to claim 1, wherein the thermoplastic resin film is a biaxially oriented polyester film or a biaxially oriented polyamide film. The laminated thermoplastic resin film according to any one of claims 1 to 9, wherein a hardness index of the coating layer defined below is 3.0 to 15.0 nm.
The coating layer hardness index is a needle with a sapphire with a radius of 75 μm at the tip, and the surface of the coating layer is scratched by applying a weight of 5 gf. Means the average value of 50 measured values of the height difference between adjacent convex portions and concave portions.   The laminated thermoplastic resin film according to any one of claims 1 to 10, wherein the haze is 1.5% or less.   The laminated thermoplastic resin film according to any one of claims 1 to 11, which is used as an optical functional film or a base film for an optical functional sheet.   The laminated thermoplastic film according to claim 12, wherein the optical functional film or the optical functional sheet is a hard coat film, an antireflection film, a light diffusion sheet, a prism sheet, a transparent conductive film, a near-infrared absorbing film, or an electromagnetic wave absorbing film. Resin film.   The laminated thermoplastic resin film according to any one of claims 1 to 13, wherein a functional layer containing an acrylic resin as a main constituent component is laminated on at least one surface of the coating layer.   The laminated thermoplastic resin film roll obtained by winding up the laminated thermoplastic resin film in any one of Claims 1-14.   The laminated thermoplastic resin film roll according to claim 15, wherein the winding length is 1500 m or more and the width is 0.5 m or more.