JP5286987B2 - Laminated thermoplastic resin film - Google Patents

Description

  The present invention relates to a laminated thermoplastic resin film mainly used for display. Specifically, the present invention relates to various functional layers (hard coat layer, light diffusion layer, prism layer, infrared absorption layer) such as an antireflection film, a light diffusion sheet, a prism sheet, an infrared absorption film, a transparent conductive film, and an antiglare film. , A transparent conductive layer, an antiglare layer, and the like).

  In general, base materials for optical functional films used for display members such as liquid crystal displays (LCD) and plasma display panels (PDP) include polyethylene terephthalate (PET), acrylic, polycarbonate (PC), and triacetyl cellulose (TAC). ), A transparent film made of 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 addition, displays such as LCDs and PDPs have been increasing in size and cost each year, and production speeds have been increased in the manufacturing process of optical functional films or optical functional sheets used as members thereof.

  In general, in the case of a biaxially oriented thermoplastic film such as a biaxially oriented polyester film, the film surface has a high crystal orientation, and thus has a drawback of poor adhesion to various paints, adhesives, inks and the like. 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.

  For example, a base film is formed by providing an adhesive modification layer mainly composed of various resins such as polyester, acrylic, polyurethane, and acrylic graft polyester on the surface of a thermoplastic resin film as a base by a coating method. A method of imparting easy adhesion to a resin is generally known. Among these coating methods, 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 contained. A water-based coating solution to be applied, dried, stretched at least in a uniaxial direction, and then subjected to a heat treatment to complete the crystal orientation of the thermoplastic resin film (so-called in-line coating method), or a thermoplastic resin film After manufacturing, a method of applying a water-based or solvent-based coating solution to the film and then drying it (so-called off-line coating method) is widely used industrially.

  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 adhesive property modification layer is generally used. 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 order to improve the blocking resistance, a method of providing irregularities on the film surface and reducing the contact area is generally employed. As a method for imparting unevenness to the film surface, generally a method for increasing the amount of inorganic particles or organic particles to be included as an additive in the adhesive modification layer or base film, or a method 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 adhesive modification layer, and voids are formed around the particles as the film is stretched. In this method, the light transmittance of the film is lowered and the haze is raised. 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.

  Regarding the adhesion, it is known that the biaxially oriented polyester film in particular has poor adhesion to a coating agent mainly composed of an acrylic resin used for a prism lens, a hard coat layer, or the like. For this reason, various proposals have been made in which an adhesive modified layer made of a polyester resin, an acrylic resin, a polyurethane resin, or a mixture thereof is formed on the surface of the polyester film. For example, in order to improve the uniformity of adhesion, the present applicant has proposed an invention relating to an easy-adhesive film roll in which the variation in the coating amount of the adhesive modified layer is reduced (see, for example, Patent Document 1). . In an example of Patent Document 1, a polyester film uniaxially stretched in the longitudinal direction, a polyester resin / polyurethane resin (= 50/50; mass%), silica particles having an average particle diameter of 1.4 μm, and a fluorine-based resin An easy-adhesive biaxially oriented polyester film obtained by applying a water-dispersible coating solution containing a surfactant, drying at 120 ° C. in a drying furnace, transversely stretching, and then heat-setting at 220 ° C. is described. Has been.

Furthermore, the present applicant has disclosed in Patent Document 2 a resin containing a copolymerized polyester / polyurethane having a specific phase separation structure and inorganic particles having an appropriate particle size on a base film made of biaxially oriented polyethylene terephthalate. A layer made of the composition is provided, and while maintaining transparency, which is a very important characteristic as an optical base film, the adhesiveness with the optical functional layer is highly excellent, and the anti-blocking property that has been increasingly demanded in recent years In addition, an excellent laminated polyester film was proposed.
JP 2004-10671 A International Publication No. 2006/57382 Pamphlet

  On the other hand, in recent years, for cost reduction, processing machines for laminating functional layers such as a lens layer on a base film have been increased in size, and the roll diameter of an easily adhesive film used as the base film is also large. It is becoming. Along with this, in order to prevent roll misalignment, the easy-adhesive film tends to be wound with high tension. In particular, the roll core portion of the roll is pressure-bonded with high pressure. For this reason, blocking is more likely to occur. Furthermore, the low molecular weight component in the adhesive modified layer may be easily transferred to the back surface when the easy-adhesive film is wound into a roll with a high pressure. As a result, for example, a laminated thermoplastic resin film having an adhesive modified layer on one side is temporarily wound and stored, and then rewound and post-processed such as an adhesive layer on the surface where the adhesive modified layer is not laminated. When trying to stack layers, the post-processed layer may cause poor adhesion or poor appearance. In addition, a hard coat layer is laminated on one side of a laminated thermoplastic resin film having an adhesive modified layer on both sides, and after winding and storing, the film is wound again and then anti-reflection layer, antifouling layer, etc. on the hard coat layer When another functional layer is to be laminated, the low molecular weight component in the adhesive modified layer is transferred onto the opposite hard coat layer during the storage, and other functions such as an antireflection layer and an antifouling layer are transferred. In some cases, this may cause poor adhesion of the layers and poor appearance.

  The present invention has an excellent adhesion and blocking resistance to the functional layer, and further to the other side of a low molecular weight component such as a fluorine compound contained in the adhesion modified layer that causes poor adhesion and poor appearance. It is an object of the present invention to provide a laminated thermoplastic resin film with less transition.

  As a result of intensive studies by the present inventors, it is an important feature that an adhesive modified layer mainly comprising a copolyester resin and a polyurethane resin contains a specific amount of a high-boiling solvent and a predetermined fluorine compound. It has been found that the above-described problems can be solved by the following means.

(1) A laminated thermoplastic resin film comprising a thermoplastic resin film and an adhesive modification layer provided on one or both sides thereof,
The adhesive modifying layer is a layer provided by coating an aqueous solution, copolymer polyester resins, polyurethane resins, containing a fluorine-based compound and high boiling solvents, halogen (provided that fluorine except) does not have a,
The high boiling point solvent has a boiling point of 150 ° C. or more and 200 ° C. or less, and its content is 0.005% by mass or more and less than 0.05% by mass with respect to the total mass of the adhesive property modified layer ,
The fluorine-based compound has an average of 6 to 16 ethylene oxide groups and a linear or branched perfluoroalkyl group having 6 to 9 carbon atoms in its molecular structure. The ratio (n / m) to the carbon number (m) of the fluoroalkyl group is 0.8 or more and 2.0 or less,
Laminated thermoplastic film.
( 2 ) The laminated thermoplastic resin film according to (1) , wherein the fluorine-based compound is at least one compound of the following (I) or (II):
(I) an addition reaction product of a perfluoropropylene polymer and polyoxyethylene having an average of 8 to 12 ethylene oxide groups in the molecular structure;
(II) Polyoxyethylene-2-perfluorohexyl ethyl ether or polyoxyethylene-2-perfluorooctyl ethyl ether having an average of 6 to 16 ethylene oxide groups in the molecular structure.
(3) The high boiling point solvent is represented by the general formula: R ¹ —O—CH ₂ —Z—CR ³ R ⁴ —O—R ^2.
(Wherein R ^{1 to} R ⁴ are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, provided that at least one of R ¹ and R ² is other than a hydrogen atom. The laminated thermoplastic resin film of (1), which is a compound represented by a single bond, a methylene group or an oxy group (—O—) .
(4) The high boiling point solvent is ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol dimethyl ether, ethylene glycol t-butyl ether, 3-methyl 3-methoxybutanol, 3-methoxybutanol, propylene glycol propyl ether, diethylene glycol Laminated thermoplastic resin of (1), which is one or more solvents selected from the group consisting of propylene glycol monomethyl ether, dipropylene glycol monoethyl ether, ethylene glycol monoethyl ether acetate and diethylene glycol monoethyl ether acetate the film.
(5) The laminated thermoplastic resin film according to any one of (1) to (3), wherein the thermoplastic resin film and / or the adhesive modification layer contains particles.
(6) The laminated thermoplastic resin film according to any one of (1) to (4), wherein the thermoplastic resin film contains substantially no particles, and at least one of the adhesive modification layers contains particles.
(7) The laminated thermoplastic resin film according to any one of (5) and (6), wherein the particles are silica particles.
(8) The laminated thermoplastic resin film according to any one of (1) to (7), wherein the haze of the laminated thermoplastic resin film is 1.5% or less.
(9) The laminated thermoplastic resin film according to any one of (1) to (8), which is used as a base film for an optical functional film or an optical functional sheet.
(10) The laminated thermoplastic resin film according to (9), wherein the optical functional film or the optical functional sheet is a prism sheet.
(11) The laminated thermoplastic resin film according to any one of (1) to (10), wherein at least one adhesive modification layer is irradiated with ultraviolet rays of 100 mJ / cm ² or more and less than 300 mJ / cm ² .

  The laminated thermoplastic resin film of the present invention is excellent in adhesion to a functional layer and blocking resistance, and even when wound into a roll at a higher pressure, an optical functional layer such as a hard coat layer or an infrared absorption layer Since the low molecular weight component (fluorine compound) in the adhesive modified layer is difficult to transfer on top, other functions such as an antireflection layer and an adhesive layer are further provided on the optical function layer such as a hard coat layer and an infrared absorption layer. Even when the layers are laminated, it has excellent coatability, adhesion, and appearance.

In this invention, adhesiveness with a functional layer is evaluated as follows.
An optical functional layer made of a curable resin is formed by irradiating a predetermined ultraviolet curable resin layer formed on the adhesive modified layer surface of the laminated thermoplastic resin film with an ultraviolet ray having a wavelength of 365 nm having a predetermined intensity. The functional layer is evaluated by the number of squares remaining without peeling after repeating the grid peel test (100 squares) with an adhesive tape twice. Specific test methods will be described in detail in the Examples section.

  The laminated thermoplastic resin film of the present invention includes a thermoplastic resin film and an adhesive modification layer. The adhesive property modification layer is provided on one side or both sides of the thermoplastic resin film.

(1) Thermoplastic resin film A thermoplastic resin film is a film made of a thermoplastic resin, and, as a typical example, an unoriented sheet obtained by melt extrusion or solution extrusion of a thermoplastic resin, if necessary, in the longitudinal direction Or the film obtained by extending | stretching to the uniaxial direction of the width direction, or carrying out the heat setting process by carrying out the sequential biaxial stretching or simultaneous biaxial stretching to a biaxial direction, and the biaxial direction is mentioned.

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

  Among these thermoplastic resins, polyethylene terephthalate, polyethylene-2,6-naphthalate, polybutylene terephthalate, polypropylene terephthalate, 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 adhesive property modified layer.

  Among them, polyethylene terephthalate, polyethylene-2,6-naphthalate, polybutylene terephthalate, polypropylene terephthalate, or a copolymer mainly composed of these resin components is more preferable, and in particular, biaxial orientation formed from polyethylene terephthalate. Films are particularly suitable.

  The thermoplastic resin may contain various additives in addition to the catalyst used for resin synthesis within a range that does not hinder the effects of the present invention. As additives, for example, particles such as inorganic particles, heat-resistant polymer particles, alkali metal compounds, alkaline earth metal compounds, phosphorus compounds, antistatic agents, ultraviolet absorbers, light-resistant agents, flame retardants, thermal stabilizers, oxidation Examples thereof include an inhibitor, an antigelling agent, and a surfactant.

  The above particles have a handling property (sliding property, running property, blocking property, air release property of the accompanying air at the time of winding, etc.) at the time of winding up or unwinding in the form of a thermoplastic resin film. For the purpose of improvement, it is used for imparting appropriate surface irregularities to the film surface.

  Inorganic particles include calcium carbonate, calcium phosphate, silica (especially amorphous silica), crystalline glass filler, kaolin, talc, titanium dioxide, alumina, silica-alumina composite oxide, barium sulfate, calcium fluoride, fluorine. And particles of 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 a polyester resin film is used as the thermoplastic resin film, among the above particles, silica particles are relatively close to the polyester resin and have a high refractive index, so that it is easy to obtain high transparency. It is. On the other hand, white pigments such as titanium dioxide are suitable for applications that require concealment. Moreover, the particle | grains contained in a thermoplastic resin film may be used alone or in combination.

  The type, average particle size, and addition amount of the particles may be appropriately selected in consideration of the balance between transparency and handling properties. For example, the average particle size is in the range of 0.01 to 2 μm, and the addition amount is What is necessary is just to determine suitably according to the use of a laminated thermoplastic resin film in the range of 0.01-5.0 mass% with respect to the total mass of a thermoplastic resin film.

  In addition, when the laminated thermoplastic resin film of the present invention is used for an application in which transparency is highly required, the thermoplastic resin film as a base material substantially contains particles that cause a decrease in transparency. It is preferable that the adhesive modified layer contain particles without containing them.

  The above-mentioned “substantially no particles are contained in the thermoplastic resin film as a substrate” means, for example, in the case of inorganic particles, 50 ppm or less when inorganic elements are quantified by fluorescent X-ray analysis, The content is preferably 10 ppm or less, and most preferably the detection limit or less. This means that even if particles are not actively added to the base film, contaminants derived from foreign substances and raw material resin or dirt attached to the line or equipment in the film manufacturing process will be peeled off and mixed into the film. It is because there is a case to do.

  Moreover, the layer structure of the thermoplastic resin film used as the substrate in the present invention may be a single layer, or a laminated structure imparted with a function that cannot be obtained with a single layer. A coextrusion method is suitable as a manufacturing method in the case of a laminated structure.

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

  The thickness of the thermoplastic resin film is preferably in the range of 30 to 300 μm, and can be arbitrarily determined according to the specifications of the application to be used. The upper limit of the thickness of the thermoplastic resin film is more preferably 250 μm, and particularly preferably 200 μm. On the other hand, the lower limit of the film thickness is more preferably 50 μm, and 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.

  A method for producing a laminated thermoplastic resin film will be described in detail below using a polyester resin as a raw material for the thermoplastic resin film as a representative example, but is not limited to this representative example.

  First, an unoriented sheet is obtained by melt-extruding polyester resin pellets which are film raw materials. The intrinsic viscosity of the pellet is preferably in the range of 0.45 to 0.70 dl / g. When the intrinsic viscosity is less than 0.45 dl / g, breakage tends to occur frequently during film production. On the other hand, if the intrinsic viscosity exceeds 0.70 dl / g, the filtration pressure rises greatly, high-precision filtration becomes difficult, and the productivity tends to decrease. In the present invention, the intrinsic viscosity is in accordance with JIS K 7367-5, and a mixed solvent of phenol (60% by mass) and 1,1,2,2-tetrachloroethane (40% by mass) is used as the solvent. Measure at ℃.

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

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

  As a method for cooling the non-oriented sheet, a method in which the molten resin is extruded in a sheet form from a slit portion of a die onto a rotating cooling drum and the sheet-like melt is brought into close contact with the rotating cooling drum, and is rapidly cooled to form a sheet It is.

  The obtained unoriented sheet is stretched 2.5 to 5.0 times in the longitudinal direction with a roll heated to 80 to 120 ° C. to obtain a uniaxially oriented polyester resin film.

  Next, an adhesion modified layer is formed. For example, in the case of forming an adhesive modified layer in-line, an aqueous coating solution described in detail in (2) Adhesive modified layer below is applied to one or both sides of the uniaxially oriented polyester resin film. It is preferable to do. Examples of the method for applying the aqueous coating solution include, for example, reverse roll coating method, gravure coating method, kiss coating method, roll brush method, spray coating method, air knife coating method, wire bar coating method, pipe doctor method, Examples of the method include impregnation / coating and curtain coating, and these methods can be used alone or in combination. Next, both ends of the film are gripped with clips, guided to a hot air zone heated to 80 to 180 ° C., stretched 2.0 to 6.0 times in the width direction after drying, and then subjected to heat setting treatment. In this heat setting treatment step, a relaxation treatment of 1 to 12% may be performed in the width direction or the longitudinal direction as necessary.

(2) Adhesive modified layer The adhesive modified layer contains a copolyester resin, a polyurethane resin, a predetermined amount of a high boiling point solvent, and a predetermined fluorine compound. The adhesion modified layer is preferably an application step or an application layer (adhesion modification) in which an aqueous coating solution containing each of the above components and water or alcohol is continuously applied to one side or both sides of a traveling thermoplastic resin film. The layer is continuously formed through a drying step for drying the quality layer), a stretching step for stretching in at least a uniaxial direction, and a heat setting treatment step for heat setting the stretched coating film.

  The adhesion modified layer of the laminated thermoplastic resin film of the present invention contains a copolymerized polyester resin and a polyurethane resin as resin components. The content of the resin component in the adhesive modified layer is preferably 45 to 95% by mass, and more preferably 50 to 90% by mass with respect to the total mass of the adhesive modified layer. When the content is less than 45% by mass, the adhesion may be reduced, and when the content exceeds 95% by mass, the blocking resistance may be reduced. The ratio (A / B) of the mass of the copolyester resin (A) and the mass of the polyurethane resin (B) in the adhesive modified layer is preferably 30/70 to 70/30. More preferably, it is 60 / 40-40 / 60. As the resin constituting the adhesive modified layer, a third resin other than the above-mentioned copolymerized polyester resin and polyurethane resin can be used in combination as long as the effects of the present invention are not impaired. Examples of the third resin include an acrylic resin. The content of the third resin is preferably 0 to 10% by mass with respect to the total mass of the resin component (including copolymer polyester resin, polyurethane resin, and third resin). Moreover, you may use a crosslinking agent together.

  The adhesion modified layer of the laminated thermoplastic resin film of the present invention contains a copolymerized polyester resin and a polyurethane resin as resin components. When the copolyester resin is used alone, the resulting adhesion modified layer has sufficient adhesion to the polyester base film, but it adheres to the acrylic resin used for the prism lens and hard coat layer. Inferior to sex. In addition, since the copolyester resin is a relatively brittle resin, the resulting adhesive modified layer is likely to cause cohesive failure due to impact during cutting. On the other hand, when a polyurethane resin is used alone, the resulting adhesion modified layer is relatively excellent in adhesion to a hard coat layer, a diffusion layer, and an acrylate resin, but adhesion to a polyester substrate film. Inferior in blocking resistance. Therefore, it is necessary to contain particles having a large particle size or increase the content of the particles. 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 having a particularly strong demand for transparency.

(2-1) Coating liquid preparation process The adhesive property modification layer is preferably formed using a coating method. The material used for the coating solution is a resin component (copolyester resin, polyurethane resin, and, if necessary, a third resin), a predetermined amount of a high-boiling solvent, a predetermined fluorine compound, and a solvent (including a dispersion medium). ). In the present invention, the coating solution used for forming the adhesive property modification layer is preferably aqueous. Moreover, additives, such as particle | grains, an antistatic agent, a ultraviolet absorber, an organic lubricant, an antibacterial agent, and a photo-oxidation catalyst, can be used as needed. In addition, a catalyst may be added to the coating solution in order to promote the thermal crosslinking reaction of the resin. For example, various chemicals such as inorganic substances, salts, organic substances, alkaline substances, acidic substances and metal-containing organic compounds can be used. Substances can be used. In order to adjust the pH of the coating solution, an alkaline substance or an acidic substance may be added. In the coating solution, the resin component is dispersed or dissolved in a dispersion medium or a solvent with stirring. Next, in addition to a predetermined amount of a high-boiling solvent and a predetermined fluorine-based compound, various additives are used in combination as required. Prepare by diluting to the desired solids concentration.

  Here, in order to uniformly disperse or dissolve the resin component in the coating solution and to remove foreign matters such as coarse particle aggregates and dust in the process, it is preferable to finely filter the coating solution.

  There is no particular limitation on the type of filter medium for finely filtering the coating solution as long as it has the above-mentioned 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 filter medium for microfiltration of the coating solution is preferably a filter medium having a filter particle size (initial filtration efficiency: 95%) of 25 μm or less, more preferably a filter medium having a filter particle size of 10 μm or less, particularly preferably a filter particle size of 5 μm or less. Filter media. Most preferred is a method using a combination of filter media having different filter particle sizes. When a filter medium having a filtration particle size exceeding 25 μm is used, removal of coarse aggregates tends to be insufficient. Therefore, the coarse aggregate that could not be removed by filtration spreads due to the orientation stress in the uniaxial or biaxial orientation process after coating and drying, and is recognized as an aggregate of 100 μm or more, which is likely to cause optical defects.

  The materials used for the coating solution will be described in detail below.

(A) Resin component (copolyester resin)
The copolyester resin used in the adhesion modified layer in the present invention preferably comprises an aromatic dicarboxylic acid component and ethylene glycol and a branched glycol as glycol components. 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, 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-naltalenedicarboxylic acid are added and copolymerized within a range of 10 mol% or less with respect to the total aromatic dicarboxylic acid component. May be.

  The copolyester resin used as the resin component of the adhesive modified layer in the present invention is preferably water-soluble or water-dispersible. Therefore, in addition to the aromatic dicarboxylic acid component, sulfophthalic acid or an alkali metal salt thereof is used in the range of 1 to 10 mol% based on the total aromatic dicarboxylic acid component in order to impart water dispersibility to the polyester. As the sulfophthalic acid, for example, sulfoterephthalic acid, 5-sulfoisophthalic acid, 4-sulfonaphthaleneisophthalic acid-2,7-dicarboxylic acid and 5- (4-sulfophenoxy) isophthalic acid or an alkali metal salt thereof Can be mentioned.

(Polyurethane resin)
The polyurethane that can be included in the composite as the polyurethane-based resin is preferably a heat-reactive polyurethane resin, and examples thereof include water-soluble or water-dispersible polyurethane in which a terminal isocyanate group is blocked with an active hydrogen group (hereinafter referred to as a block). .

  Examples of the blocking agent for the isocyanate group include bisulfites, phenols, alcohols, lactams, oximes and esters such as dimethyl malonate, diketones such as methyl acetoacetate, mercaptans, ureas, and imidazoles. And acid imides such as succinimide, amines such as diphenylamine, imines, and carbamates such as 2-oxazolidine. The water-soluble or water-dispersible polyurethane preferably has a hydrophilic group in the molecule. Therefore, it is preferable to use a compound having a hydrophilic group in the compound having at least one active hydrogen atom in the molecule to be used or a compound having hydrophilicity in the above-mentioned blocking agent. Examples of having a hydrophilic group in a compound having at least one active hydrogen atom in the molecule to be used include taurine, dimethylolpropionic acid, polyester polyol having carboxylic acid group or sulfonic acid group, polyoxyalkylene polyol, etc. Is mentioned. Examples of the hydrophilic compound in the blocking agent include bisulfites and phenols containing a sulfonic acid group. When heat energy is applied to the resin during drying or heat setting during film production, the blocking agent is released from the isocyanate group, so the resin fixes a water-dispersible copolyester resin mixed in a self-crosslinked stitch. And reacts with the terminal groups of the resin. In particular, as the water-soluble or water-dispersible polyurethane, those using a hydrophilic compound as a blocking agent are preferable. These polyurethanes are poor in water resistance because the resin in the coating liquid preparation 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, A coating film with good water resistance is obtained.

  The chemical composition of the urethane prepolymer used in the polyurethane resin is (1) a compound having at least two active hydrogen atoms in the molecule and a molecular weight of 200 to 20,000, and (2) two or more in the molecule. (3) A compound having a terminal isocyanate group obtained by reacting an organic polyisocyanate having an isocyanate group and, if necessary, (3) a chain extender having at least two active hydrogen atoms in the molecule.

  Generally known as a compound having a molecular weight of 200 to 20,000 having at least two active hydrogen atoms in the molecule of (1), two or more hydroxyl groups, carboxyl groups, Particularly preferred compounds include an amino group or a mercapto group, and examples thereof include polyether polyol and polyester polyol.

  Polyester polyols include polysaturated or unsaturated carboxylic acids such as succinic acid, adipic acid, phthalic acid and maleic anhydride, or the carboxylic acid anhydride, and ethylene glycol, diethylene glycol, 1,4-butanediol. Polyvalent saturated and unsaturated alcohols such as neopentyl glycol, 1,6-hexanediol and trimethylolpropane, polyalkylene ether glycols such as relatively low molecular weight polyethylene glycol and polypropylene glycol, or alcohols thereof Can be obtained by condensation.

  Furthermore, as the polyester polyol, polyesters obtained from lactone and hydroxy acid, and polyester polyols obtained by adding ethylene oxide, propylene oxide or the like to previously produced polyesters can also be used.

  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. -Addition of alicyclic diisocyanates such as dicyclohexylmethane diisocyanate, aliphatic diisocyanates such as hexamethylene diisocyanate and 2,2,4-trimethylhexamethylene diisocyanate, or one or more of these compounds to trimethylolpropane, etc. Examples include polyisocyanates obtained.

  Examples of the chain extender having at least two active hydrogen atoms in the molecule (3) include glycols such as ethylene glycol, diethylene glycol, 1,4-butanediol, and 1,6-hexanediol, glycerin, triglyceride, and the like. Polyols such as methylolpropane and pentaerythritol, diamines such as ethylenediamine, hexamethylenediamine, and piperazine, amino alcohols such as monoethanolamine and diethanolamine, thiodiglycols such as thiodiethylene glycol, or water Is mentioned.

  In order to synthesize a urethane prepolymer, it is usually 150 ° C. or lower by a single-stage or multi-stage isocyanate polyaddition method using the above (1) and (2), and further, if necessary, the above (3). The reaction is preferably performed at a temperature of 70 to 120 ° C. for 5 minutes to several hours. The ratio of the isocyanate group of (2) to the active hydrogen atom of (1) and (3) can be freely selected as long as it is 1 or more, but free isocyanate groups remain in the obtained urethane prepolymer. is necessary. Furthermore, the content of free isocyanate groups may be 10% by mass or less with respect to the total mass of the urethane prepolymer to be obtained. However, in consideration of the stability of the aqueous solution of the urethane polymer after blocking, 7 It is preferable that it is below mass%.

  The urethane prepolymer obtained is preferably blocked with terminal isocyanate groups using bisulfite. The urethane prepolymer is mixed with an aqueous bisulfite 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, the reaction mixture is diluted with water to an appropriate concentration to obtain a heat-reactive water-soluble urethane resin composition. When the composition is used, it is adjusted to an appropriate concentration and viscosity. However, when heated to about 80 to 200 ° C., the bisulfite as a blocking agent is dissociated to regenerate active terminal isocyanate groups. A polyurethane polymer is produced by a polyaddition reaction that occurs within or between molecules of the prepolymer, or has the property of causing addition to other functional groups.

(B) High-boiling solvent It is important that the coating solution contains a specific amount of a high-boiling solvent highly compatible with a predetermined fluorine-based compound. The content of the high boiling point solvent in the coating solution is preferably 3% by mass or less with respect to the total mass of the coating solution. When the content of the high boiling point solvent in the coating solution exceeds 3% by mass, the blocking resistance may be lowered. By including the specific amount of the high-boiling solvent in the coating solution, the high-boiling solvent can be left in the adhesive modified layer within the range of 0.005% by mass or more and less than 0.05% by mass. In addition, in the heat setting treatment process during film formation, the fluorinated compound can be stably present in the adhesion-modified layer, and bleed-out can be suppressed to the minimum. Until now, it has been thought that when a high-boiling solvent remains in the coating layer (adhesive modified layer), blocking or other harmful effects occur. In the present invention, a specific amount of high-boiling solvent is added to the adhesive modified layer. It has been found that the surprising effect as described above can be obtained by making it remain.

  As a method of adding a high boiling point solvent, in order to improve the water solubility or water dispersibility of the copolymer polyester resin in an aqueous coating solution, the copolymer polyester system is mixed with water as a dispersion medium or a solvent. It is preferable to add to the resin and stir for 2 hours or longer under conditions of 150 ° C. or higher and 180 ° C. or lower. By this heating and stirring treatment, the high boiling point solvent can be stably present in the adhesion-modified layer with a relatively small addition amount.

The high boiling point solvent used in the present invention is a solvent having a boiling point of 150 ° C. or higher, and preferably a compound represented by the general formula: R ¹ —O—CH ₂ —Z—CR ³ R ⁴ —O—R ^2. is there. Here, R ^{1 to} R ⁴ are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, preferably a hydrogen atom or an alkyl group having 1 to 2 carbon atoms. However, at least one of R ¹ and R ² is other than a hydrogen atom. -Z- is a single bond, a methylene group or an oxy group (-O-). Examples of such high boiling point solvents include ethylene glycol monobutyl ether (butyl cellosolve) [boiling point: 171 ° C.], diethylene glycol monobutyl ether [boiling point: 230 ° C.], diethylene glycol monomethyl ether [boiling point: 193 ° C.], diethylene glycol dimethyl ether [boiling point: 162 ° C], ethylene glycol t-butyl ether [boiling point: 152 ° C], 3-methyl 3-methoxybutanol [boiling point: 174 ° C], 3-methoxybutanol [boiling point: 160 ° C], propylene glycol propyl ether [boiling point: 150 ° C]. ], Dipropylene glycol monomethyl ether [boiling point: 190 ° C], dipropylene glycol monoethyl ether [boiling point: 198 ° C]. In addition to these, ethylene glycol monoethyl ether acetate [boiling point: 160 ° C.], diethylene glycol monoethyl ether acetate [boiling point: 217 ° C.] and the like can also be mentioned. These high boiling point solvents may be used alone or in combination of two or more.

  Moreover, in order to prevent blocking between films when unwinding the laminated thermoplastic resin film wound up in a roll shape, it is preferable to select a solvent having a boiling point of 200 ° C. or less as a high boiling point solvent.

  Of these, butyl cellosolve and 3-methyl 3-methoxybutanol are particularly preferred from the viewpoints of water dispersibility of the resin component and applicability of the coating solution.

  In addition, the organic solvent used industrially is generally assigned a CAS number, and safety data including physical property values such as boiling point is published on the Internet. In the case where the boiling point is not described in the published data, for example, by using a boiling point measuring device devised by Sakurai and Ikeda (“Chemical Dictionary 3” Kyoritsu Shuppan (1960), p. 831), The boiling point can be measured.

  When the coating liquid is an aqueous solution or aqueous dispersion of a copolyester resin, the mixing ratio (weight) of the copolyester resin (A), the high-boiling solvent (C), and water (D) as the solvent or dispersion medium The ratio is preferably adjusted to 2 to 5 for (A) / (C) and 0.1 to 1 for (C) / (D).

  Specifically, from the viewpoint of the dispersibility of the copolyester resin, the mixing ratio of the high boiling point solvent (C) to the copolyester resin (A) is preferably 5 or less.

On the other hand, from the following points, it is preferable that (A) / (C) is 2 or more, or (C) / (D) is 1 or less.
(A) Since the surface quality of the adhesive modified layer such as coating spots can be prevented from being deteriorated, when used as an optical base film, it can be adapted to high definition required in recent years.
(B) It is possible to prevent a decrease in blocking resistance due to an increase in the residual amount of the high boiling point solvent in the adhesion modified layer.
(C) Since it is not necessary to increase the content of the high boiling point solvent in the dispersion, it is advantageous in terms of cost.
(D) There is little risk of explosion and environmental pollution due to excessive high boiling point solvent.
(E) When applying and drying the coating solution, it is not necessary to lengthen the drying time.

  In addition, by setting (C) / (D) to 0.1 or more, bleeding out of the fluorine-based compound to the surface can be suppressed in the heat setting treatment step during film production. Therefore, the amount transferred to the other surface of the fluorine-based compound can also be reduced.

  The content of the high boiling point solvent in the adhesive modified layer in the present invention is 0.005% by mass or more and less than 0.05% by mass with respect to the total mass of the adhesive modified layer. The upper limit of the content of the high boiling point solvent is preferably less than 0.04% by mass, and more preferably less than 0.03% by mass. When the content of the high-boiling solvent is less than 0.005% by mass, the fluorine-based compound cannot be stably present in the adhesive property-modified layer, and the fluorine is likely to be set off. Furthermore, the leveling of the coating layer (adhesion modified layer) decreases, and the appearance shape tends to deteriorate, such as the occurrence of coating lines. When the content of the high boiling point solvent is 0.05% by mass or more, the blocking resistance is lowered, and the drying time of the coating solution is prolonged, which is not preferable.

  Further, in the method for producing a laminated thermoplastic resin film of the present invention, in order to leave the high boiling point solvent in the adhesive modified layer in a content within the above range, the temperature control in the heat setting treatment step is very high. is important. Hereinafter, the embodiment will be described in detail.

  As will be described later, in the heat setting treatment step of the present invention, the residual amount of the high boiling point solvent in the adhesive modified layer greatly depends on the heat treatment conditions. That is, it is important to appropriately set the maximum temperature and the time required to reach the maximum temperature in the heat setting process.

  The maximum temperature in the heat setting treatment step is preferably set in the range of not less than the boiling point of the high-boiling solvent and less than + 80 ° C. of the boiling point of the high-boiling solvent. If the maximum temperature is less than the boiling point of the high-boiling solvent, it is difficult to control the remaining amount of the high-boiling solvent in the adhesive modified layer within the above range. The remaining amount of the fluorine is less than the above range, and the bleedout of the fluorine compound increases.

(C) Fluorine Compound In the present invention, a fluorine compound is added to the coating solution in order to uniformly apply the coating solution. The fluorine-based compound in the present invention has an average of 6 to 16 ethylene oxide groups in the molecular structure. Furthermore, the fluorine-based compound desirably has a perfluoroalkyl group (Rf) having a function of reducing the surface tension. Such a fluorine compound acts as a surfactant, improves the wettability of the film, and can uniformly apply the coating solution. The carbon number (m) of the perfluoroalkyl group (Rf) is preferably 6 to 9. When the carbon number of Rf is 6 to 9, the dispersibility of the resin component in the aqueous coating solution is good due to the surface active effect, and the leveling property of the coating layer (adhesiveness modified layer) is good. Such a perfluoro group (Rf) can be preferably used even if it is linear or branched.

  The inventor of the present application examined the transition to the other side by bleeding out of a low molecular weight component containing fluorine. When a compound having a halogen other than fluorine is contained in the adhesive modified layer, the fluorine-based compound is I found that it tends to bleed out. This is presumed to be due to the following reasons. (1) A compound having a halogen other than fluorine cleaves an ethylene oxide group, which is a hydrophilic group of the fluorine-based compound, causing a decrease in the molecular weight of the fluorine-based compound. (2) A compound having a halogen other than fluorine is a fluorine-based compound. The hydrophilic group of the fluorine compound is divided, and the hydrophilicity of the fluorine compound decreases. (3) By-products generated by cleavage of the hydrophilic group (ethylene oxide group) of the fluorine compound bleed out. For this reason, the present invention is characterized in that the adhesion modified layer does not contain halogen (however, excluding fluorine). Examples of the halogen (excluding fluorine) in the present invention include chlorine (Cl), bromine (Br), and iodine (I). In particular, chlorine (Cl) has a high electron affinity and a high reactivity, and therefore needs to be removed from the adhesive modified layer.

  The presence / absence of halogen (excluding fluorine) in the adhesive modified layer should be known using various chromatographic methods such as liquid chromatography, mass spectrometry, ion chromatography, etc. (details will be described later). Can do. Here, “has no halogen (excluding fluorine)” means that the concentration of halogen (excluding fluorine) on the surface of the adhesive modified layer measured by the above measurement method is 1 ppm or less. Say. In addition, it is desirable that halogen (excluding fluorine) is 0 ppm, but 1 ppm is considered to be the lower limit in consideration of measurement error.

For the above reason, it is important that the coating solution for forming the adhesion modified layer used in the present invention does not contain halogen (excluding fluorine). Therefore, it is necessary to use a fluorine-based compound that does not include a compound having halogen (excluding fluorine). In the production of certain fluorine-based compounds, a compound having a halogen other than fluorine, such as chlorine, may remain in the final product as a by-product or an unreacted product. For example, a fluorine-based compound composed of a compound having a structure in which an Rf group is bonded to a hydrophilic group via a polar group such as —SO ₂ — or —CO— is used when a hydrophilic group is introduced with a halogen such as chlorine. A substitution reaction may be performed on a hydrophilic group having a terminal. In this case, a compound having a halogen other than fluorine remains in the final product as an unreacted product, but such a compound is usually difficult to remove by fractional distillation or distillation. Therefore, as the fluorine-based compound used in the present invention, it is desirable that the compound having a halogen other than fluorine does not remain, and a fluorine-based compound in which a compound having a halogen other than fluorine is not generated as an unreacted product or by-product is selected. It is further desirable to do so.

Since the fluorine-based compound of the present invention has an affinity for an aqueous coating solution, it has an ethylene oxide group (— (CH ₂ —CH ₂ —O) _n —) as a hydrophilic group in the molecular structure. To do. Carboxylic acid groups and sulfonic acid groups are not preferred as hydrophilic groups because they do not have an affinity for aqueous coating solutions. The number of ethylene oxide groups is important for achieving both prevention of bleed out and applicability. Therefore, the fluorine compound used in the present invention is characterized in that the number (n) of ethylene oxide groups is 6 to 16 on average. If the number of ethylene oxide groups is 6 or more, the fluorine-based compound has a high molecular weight, and therefore tends to be more hydrophilic and less likely to bleed out, and also has a high boiling point, so it is less likely to evaporate even during heat treatment after coating. It is. If the number of ethylene oxide groups exceeds 16, the hydrophilicity of the fluorine-based compound becomes strong, so that the coating property of the resulting coating solution tends to decrease, and a film using such a coating solution is used as an optical substrate. In such a case, it is impossible to obtain a sufficiently uniform coating property that satisfies the high definition required in recent years. Further, the ratio (n / m) of the number (n) of ethylene oxide groups to the carbon number (m) of the perfluoroalkyl group (Rf), that is, the balance between the hydrophilic group and the hydrophobic group is from 0.8. 2.0 is preferred. When n / m exceeds 2.0, the coating property of the coating solution is lowered, and when n / m is smaller than 0.8, the coating solution tends to repel, which is not preferable. In addition, the average number of ethylene oxide groups in the molecular structure of the fluorine-based compound (average number of added moles of ethylene oxide) can be determined by measuring a specific signal derived from the ethylene oxide group by liquid chromatography, mass spectrometry, and NMR. it can.

As a fluorine compound, an ethylene oxide adduct compound compound of a perfluoroalkylene polymer or a fluorine compound in which a linear perfluoroalkyl group is bonded to polyoxyethylene through an ether bond is excellent in a small amount. This is suitable in that it has the ability to reduce the tension. Among these, the following compounds (I) or (II) are more preferable.
(I) an addition reaction product of a perfluoropropylene polymer and polyoxyethylene having an average of 8 to 12 ethylene oxide groups in the molecular structure;
(II) Polyoxyethylene-2-perfluorohexyl ethyl ether or polyoxyethylene-2-perfluorooctyl ethyl ether having an average of 6 to 16 ethylene oxide groups in the molecular structure.
Here, the perfluoropropylene polymer (I) is preferably a dimer having 6 carbon atoms or a trimer having 9 carbon atoms. In addition, the fluorine-based compounds (I) and (II) can achieve both sufficiently uniform coatability and suppression of bleed-out, and also have good affinity for high-boiling solvents and prevent bleed-out. It is suitable for. Since polyoxyethylene-2-perfluorooctyl ethyl ether has more perfluoro groups (Rf) than polyoxyethylene-2-perfluorohexyl ethyl ether, the ratio (n / m) is within the above range. Thus, the number of ethylene oxide groups is more preferably 7 or more.

  Fluorine-based compounds that can be used in the present invention are described in reference numbers 7-1720, 7-1326, etc. of “Existing Chemical Substances List” published by the Ministry of International Trade and Industry. At least 10 kinds of such fluorine-based compounds are put on the market. Has been. The fluorine compound used in the present invention preferably has no sulfonic acid structure from the viewpoint of environmental protection. As the fluorine-based compound used in the present invention, a commercially available product may be used as it is, and it is preferably used after purification by solvent washing, distillation, recrystallization, chromatography, adsorption or the like. Further, in the present invention, the above-mentioned fluorine-based compound may be used alone, and as long as the effect of the present invention is not impaired, the combination of two or more fluorine-based compounds is prevented as necessary. is not.

  The amount of the fluorine compound added to the coating solution should be within a range that does not impair adhesion to the acrylic resin for hard coats and lenses, provides good coating properties, and does not cause setback due to bleed out. Can be selected as appropriate. For example, the addition amount of the fluorine-based compound to the coating solution is preferably 30 times or less from the critical micelle concentration with respect to pure water. When the addition amount of the fluorine-based compound exceeds 30 times the critical micelle concentration, the particles contained in the coating solution are likely to aggregate, resulting in an increase in the haze of the obtained laminated film, and in particular, an optical functional film or optical functional property. It is not preferable as a base film of a sheet. In addition, the fluorine-based compound may bleed out on the surface of the adhesive modified layer, which may adversely affect the adhesion. On the other hand, when the addition amount of the fluorine-based compound is less than the critical micelle concentration, good coatability cannot be obtained. In this invention, it is preferable that the addition amount of a fluorine-type compound is 0.01-0.18 mass% with respect to the total mass of a coating liquid, Moreover, with respect to the total solid content which comprises an adhesive property modification layer. And preferably less than 1.5 mass%. When the added amount of the fluorine compound is 1.5% by mass or more with respect to the total solid content of the adhesive modified layer, the fluorine compound bleeds out to the surface of the adhesive modified layer, resulting in increased setback. Furthermore, there are cases where the adhesiveness is adversely affected.

(D) Solvent In the present invention, the solvent broadly includes not only a liquid for dissolving the resin component but also a dispersion medium used for dispersing the resin component in the form of particles. In order to carry out the present invention, various solvents such as an organic solvent and an aqueous solvent can be used.

  The solvent used in the coating solution is preferably a mixed solvent of water and alcohols such as ethanol, isopropyl alcohol, and benzyl alcohol, and the amount used is preferably 30 to 50% by mass with respect to the total mass of the coating solution. is there. Moreover, you may mix organic solvents other than alcohol in less than 10 mass% with respect to the total amount of solvents in the range which can melt | dissolve or disperse | distribute a resin component.

  In the above mixed solvent, the amount of the organic solvent (alcohols and other organic solvents) added is less than 50% by mass with respect to the total amount of the solvent. When the amount of the organic solvent added is less than 50% by mass, the drying property is improved during coating and drying, and the appearance of the coating layer (adhesive modified layer) is improved as compared with the case of water alone. . When the addition amount of the organic solvent is 50% by mass or more, the evaporation rate of the solvent is increased, and the concentration of the coating solution is likely to change 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 layer (adhesion modified layer). Furthermore, due to the volatilization of the organic solvent, there is a high risk of fire and the like.

(E) pH adjustment of coating solution The coating solution preferably has a pH in the range of 5 or more and less than 8. When the pH of the coating solution is less than 5, the adhesion between the resulting laminated film and the functional layer tends to be inferior. On the other hand, when the pH of the coating solution is 8 or more, when particles are used as an additive, depending on the type, remarkable aggregation occurs, and the haze of the resulting laminated film is increased to deteriorate transparency, which is not preferable. In order to bring the pH of the coating solution within the above range, a pH adjuster may be used. As such a pH adjuster, adhesion, blocking resistance, applicability are not adversely affected, or can be ignored. If there is no particular limitation. For example, sodium bicarbonate or sodium carbonate can be used to increase the pH, and acetic acid or the like can be used to decrease the pH.

(F) Particles For example, a laminate obtained by containing particles having an appropriate particle size in an adhesive modified layer laminated by an in-line coating method and forming appropriate irregularities on the surface of the adhesive modified layer The slipping property, winding property and scratch resistance of the thermoplastic resin film can be improved.

  The haze of the laminated thermoplastic resin film of the present invention is preferably 1.5% or less when used as an optical functional film or a base film of an optical functional sheet that is highly required for transparency. The haze is more preferably 1.0% 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 (thermoplastic resin film). When particles are not included in the base film, scratch resistance of the laminated thermoplastic resin film and handling property when winding or unwinding (sliding property, running property, blocking property, air at the time of winding) In order to improve the air release property of the adhesive modified layer, it is preferable to include a specific amount of particles having an appropriate size in the adhesive modified layer to form appropriate irregularities on the surface of the modified adhesive layer.

  Particles to be included in the adhesive modification layer include calcium carbonate, calcium phosphate, amorphous silica, crystalline glass filler, kaolin, talc, titanium dioxide, alumina, silica-alumina composite oxide, barium sulfate, calcium fluoride. Inorganic particles such as lithium fluoride, zeolite, molybdenum sulfide, mica, crosslinked polystyrene particles, crosslinked acrylic resin particles, crosslinked methyl methacrylate resin particles, benzoguanamine / formaldehyde condensate particles, melamine / formaldehyde condensate particles, polytetra Examples thereof include heat-resistant polymer particles such as fluoroethylene particles.

  Among these particles, silica particles are preferable because the refractive index is relatively close to the resin component of the adhesive modification layer, and thus a film having high transparency can be easily obtained.

  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 adhesive modified 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 total mass of the adhesive modified layer. To do. When the content of the particles in the adhesion modified layer exceeds 20% by mass, the transparency of the obtained laminated film is deteriorated, and the adhesion with the functional layer 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 total mass of the adhesive modified layer.

  The average particle diameter of the particles is 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 of the laminated film, and scratch resistance tends to deteriorate. On the other hand, when the average particle diameter of the particles exceeds 150 nm, the haze of the obtained laminated film increases, and the particles easily fall off, which is not preferable.

  Further, in the adhesion modified layer, two or more kinds of particles having different average particle diameters may be contained, or the same kind of particles having different average particle diameters may be contained. It suffices if the particle size and the total content are within the above ranges. When applying the coating solution, as described in the above item (2-1), it is preferable to precisely filter the coating solution immediately before coating in order to remove coarse aggregates of particles in the coating solution. .

  In the present invention, sufficient blocking resistance and scratch resistance may not be obtained only with 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) 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, slipping property, and winding property may be deteriorated. On the other hand, when the average particle diameter of the particles (P2) exceeds 1000 nm, the haze tends to increase. Further, the particles (P2) are preferably aggregate particles in which primary particles are aggregated, and it is preferable to use particles having a ratio of the average particle size in the aggregated state to the average particle size of the primary particles of 4 times or more. It is preferable from the point of scratch property.

  When two types of particles (P1) and (P2) are used, for example, particles (P1) (average particle size: 20 to 150 nm) and particles (P2) (average particle size: 160 to 1000 nm) in the adhesion-modified layer. ) Content ratio (P1 / P2) is 5 to 30, and the content of particles (P2) is 0.1 to 1% by mass with respect to the total mass of the adhesive modified layer. Controlling the content of two kinds of particles having specific particle sizes within the above range optimizes the three-dimensional center plane average surface roughness of the surface of the adhesion-modified layer, and the transparency and handling properties of the resulting laminated film ( It is suitable for achieving both blocking resistance and the like. When the content of the particles (P2) exceeds 1% by mass with respect to the total mass of the adhesive property modified layer, the haze tends to increase remarkably.

The average particle size and average primary particle size of the particles are measured by the following method.
Using an electron microscope, the particles are photographed at a magnification such that the size of one smallest particle is 2 to 5 mm, the maximum diameter of 300 to 500 particles is measured, the average value thereof is obtained, the average The particle size or average primary particle size is used. In addition, when obtaining the average particle size of the particles in the adhesion modified layer of the laminated film, a cross section of the laminated film is photographed at a magnification of 120,000 using a transmission electron microscope (TEM) to improve the adhesion. The maximum diameter of the particles present in the cross section of the layer is measured, the average value thereof is obtained, and the average particle diameter is obtained. The average particle size of the particles (P2) made of aggregates is 300 to 500 aggregate particles present in the cross section obtained by photographing a cross section of the adhesive modified layer of the laminated film at a magnification of 200 times using an optical microscope. It is obtained by measuring the maximum diameter of and determining the average value thereof.

(2-2) Coating step The step of coating the aqueous coating solution is preferably performed by a so-called in-line coating method, which is performed during the manufacturing process of the thermoplastic resin film (base film). More preferably, the aqueous coating solution is applied to the base film before crystal orientation is completed. The solid content concentration in the aqueous 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 base film coated with the aqueous coating solution is guided to a tenter for crystal orientation and heat setting, and heated there to form a stable coating (adhesive modified layer) by thermal crosslinking reaction, and then laminated. Become a film.

(Amount of application)
It is preferable to manage the final coating amount of the adhesive modification layer (solid content mass per unit area of the film) at 0.005 to 0.20 g / m ² . If the coating amount is less than 0.005 g / m ² , the adhesion between the obtained laminated film and the functional layer may be insufficient. On the other hand, when the coating amount exceeds 0.20 g / m ² , the blocking resistance decreases. Further, 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 adhesion modified layer. In the prior art, if the coating amount is less than 0.05 g / m ^2, it is difficult to obtain sufficient adhesion. When the adhesive modified layer is provided on both sides of the base film, the coating amount of the adhesive modified layer on both sides may be the same or different, and each is independent depending on the use of the laminated film. Can be set within the above range.

The thickness of the adhesive modified layer can be measured by cutting the cross section of the adhesive modified layer with a microtome and observing with an electron microscope. However, if the adhesive modified layer is soft, it may be deformed during cutting. is there. For simplicity, if the coating amount is known, the thickness can be converted from the density of the adhesive modified layer. For example, when the density of the adhesive modified layer is 1 g / cm ³ , the thickness corresponds to 1 μm if the coating amount is 1 g / m ² . The density of the adhesive modified layer is determined by calculating the density of each material from the resin component constituting the adhesive modified layer and the type of particles added as necessary, and multiplying the density of each material by the mass ratio of the material. By obtaining the sum, the thickness of the adhesive modified layer can be estimated.

  In the drying furnace used in the drying step of the present invention, the maximum temperature (maximum drying temperature) of the drying air on the coated surface is preferably 120 ° C. or higher and 150 ° C. or lower, and more preferably 130 ° C. or higher and 150 ° C. or lower. When the maximum drying temperature is less than 120 ° C., the drying rate is decreased, and the bleedout amount of the fluorine-based compound is increased. On the other hand, when the maximum drying temperature is 150 ° C. or higher, the base film is easily crystallized, and the frequency of occurrence of breakage during transverse stretching increases.

The heat setting treatment is usually carried out by blowing hot air on the surface of the coating layer (adhesive property modification layer) of the laminated film. The temperature in the heat setting treatment step (temperature of hot air) may be appropriately set within a temperature range of 100 to 260 ° C., although there is a slight difference depending on the type of constituent resin of the thermoplastic resin film as the base material. The maximum temperature in the heat setting treatment step is preferably controlled at 210 to 240 ° C, more preferably the lower limit is 225 ° C and the upper limit is 235 ° C. Hereinafter, a case where polyethylene terephthalate, which is a typical thermoplastic resin, is used as a base film will be described as an example.
(UV irradiation process)
Preferably, the adhesive property modified layer obtained as described above is irradiated with ultraviolet rays of 100 mJ / cm ² or more and less than 300 mJ / cm ² . By performing such irradiation, the adhesive modified layer is hardly deteriorated, so that there is almost no concern that the adhesiveness of the laminated film to the functional layer is significantly reduced, and fluorine on the surface of the adhesive modified layer is eliminated. The amount of can be reduced. When the adhesive property modification layer is provided on both surfaces of the thermoplastic resin film, the adhesive property modification layer on both surfaces or only one surface may be subjected to ultraviolet irradiation.

  The laminated thermoplastic resin film of the present invention can be suitably used for a PDP panel, a liquid crystal display, a solar cell, an organic EL, and the like as an optical functional film or a base film of an optical functional sheet. In particular, it is suitable as a prism sheet used in a display panel or the like. A prism sheet is an optical film in which a prism pattern made of acrylic resin having a relatively high refractive index of 1.55 to 1.60 is uniformly formed on the surface of a transparent resin film, and is incorporated into the front surface of the backlight. Therefore, of the light emitted from the light source, the light that is not used outside the viewing angle is recycled by reflection and refraction, and is condensed in the direction of the user at the optimum angle, thereby improving the front brightness. It is an important member.

  Next, although the structure of the laminated thermoplastic resin film of this invention, an effect, and a manufacturing method are demonstrated using an Example and a comparative example, this invention is naturally not limited to these Examples. Moreover, evaluation of each film of an Example was performed in accordance with the following method.

(1) Adhesiveness About 5 g of hard coat agent (manufactured by Dainichi Seika, Seika Beam EXF01 (B)) is placed on a glass plate having a thickness of 5 mm kept clean, and the adhesion modified layer surface of the film sample and the hard coat agent Were stacked so that the hard coating agent was stretched by a manually loaded rubber roller having a width of 10 cm and a diameter of 4 cm from above the film sample. 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. A 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 through the hard coat layer and the adhesion modified layer and reached 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. The number of cells that were peeled off, including those that were partially peeled, was visually counted, and the adhesion (%) was determined from the following formula.
Adhesiveness (%) = (1-number of cells peeled off / 100) × 100
Adhesion (%) is 80% or more ○
Adhesion (%) is 79% or less x
It was.

(2) Content of high boiling point solvent The amount of residual solvent was measured as follows using a packed column type gas chromatograph. About 20 mg of the film sample is accurately weighed, and the glass insert containing the film sample is set in the gas chromatograph inlet, heated at 150 ° C. for 5 minutes at the gas chromatograph inlet, and a high boiling point solvent is added to the column tip at room temperature. After trapping, the high boiling point solvent was measured and quantified under the following conditions (A: ppm). Further, after weighing (B: g) a film sample cut into a 10 cm square, the adhesive modified layer was wiped with a solvent, and the weight difference (C: g) between the film sample before and after wiping was determined. The residual solvent amount was calculated using the following formula.
High boiling point solvent amount (%) in coating layer (adhesion modified layer) = A × B × 10 ⁻⁴ / C
(In addition, when the adhesive modification layer is formed with the same coating amount on both surfaces of the base material, it is set to 1/2 of the above calculation result, and when the coating amount is different, it is prorated according to the thickness ratio of the coating layer. )
Device: GC-14 type (manufactured by Shimadzu Corporation)
Column: ID 3mm, length 1.6m
Filler: Themon-1000 (5%) / KOH impregnated stationary phase: chromosorb W-AWCS
Carrier gas: Nitrogen (flow rate 40ml / min)
Oven temperature: 60-190 ° C (temperature increase rate 10 ° C / min)
Detector: Hydrogen flame ionization detector (FID)
Detection temperature: 240 ° C
In quantitative analysis, a calibration curve was prepared and used for quantification.
For example, when the high boiling point solvent is butyl cellosolve, 2 μl of a 1000 μg / ml methanol solution was injected into the injection port, trapped at 150 ° C. for 5 minutes, measured under the above conditions, and a calibration curve was created from the peak area.

(3) Fluorine set-off property The surface of the adhesion modified layer of the film sample and the surface of the polyester resin film which does not substantially contain particles are superposed, and a pressure of 1 kgf / cm ² is applied to this, and 50 ° C., 60% RH. Then, the film was peeled off for 24 hours, and the surface fluorine content of the polyester resin film substantially free of particles was determined by the following method.

  The atomic concentration ratio (F / C) of fluorine and carbon on the measurement surface was determined by X-ray photoelectron spectroscopy using ESCA-3400 manufactured by KRATOS according to the following procedure. The sample film was cut to an appropriate size using clean stainless steel scissors and fixed on a stainless steel sample support using double-sided tape or the like. At this time, the area of the double-sided tape was made equal to or smaller than the area of the sample to eliminate the influence from the double-sided tape.

MgKα1,2 was used as the X-ray source, and the output was set to 10 kV and 20 mA. The detector has a pass energy of 75 eV and a photoelectron escape angle of 90 degrees. Measurement was performed at a pitch of 0.1 eV, measurement time was 200 ms per pitch, and integration was performed 10 times or more. During the measurement, the degree of vacuum in the sample chamber was kept between 1 × 10 ⁻⁵ Pa and 1 × 10 ⁻⁶ Pa. As correction of the peak accompanying charging during measurement, the binding energy value of the main peak of C1s was adjusted to 284.8 eV.

The peak area of C1s was obtained by drawing a straight base line in the range of binding energy of 280 to 292 eV, and the peak area of F1s was found by drawing a straight base line in the range of 684 to 694 eV. As the intensity of the two end points when drawing a straight line, a value obtained by numerically averaging the intensity of 10 points in the vicinity of each end point was used. The atomic concentration ratio (F / C) of fluorine and carbon on the surface is as follows according to the atomic ratio calculated by dividing the ratio of the F1s peak area to the C1s peak area by the sensitivity correction value unique to the apparatus. evaluated. In this example, Kratos ESCA-3400 was used as the X-ray photoelectron spectrometer, and the sensitivity correction value unique to this apparatus was 0.1099.
F / C 0 or more, less than 0.005 ○
0.005 or more, less than 0.008 △
0.008 or more, ×

(4) Blocking resistance The coating layer (adhesion modified layer) surfaces of two film samples were overlapped with each other, a pressure of 1 kgf / cm ² was applied thereto, and the atmosphere was 50 ° C. and 60% RH for 24 hours. After making it adhere, it peeled and the peeling state was determined on the following reference | standard.
○: The adhesive-modified layer is not transferred and can be peeled lightly. △: A peeling sound is generated, and the adhesive-modified layer is partially transferred to the other surface. ×: Two films are fixed. That cannot be peeled off or that can be peeled off, but the polyester film that is the substrate is cleaved

(5) Presence / absence of halogen The presence / absence of halogen other than fluorine in the adhesion-modified layer was examined by the following method. 3.0 g of film samples obtained in Examples and Comparative Examples were cut finely and extracted with 20 ml of methanol (in a sealed container, room temperature, immersion for 2 hours). After 10 ml of the extract is gently heated and concentrated to 1 ml, 0.1 ml of the concentrate is completely burned by the oxygen flask combustion method, the generated acid gas is absorbed by the alkali absorbent, and the halogen is removed using ion chromatography. The presence or absence was examined. The ion chromatography was performed under the following conditions.
[Ion chromatography conditions]
Device: DX-120 (manufactured by Nippon Dionex)
Column: AS12A (inner diameter 4 mm)
Mobile phase: sodium carbonate (2.7 mmol / L), sodium bicarbonate (0.3 mmol / L)
Flow rate: 1.5 ml / min Column temperature: 25 ° C
In quantitative analysis, a calibration curve was prepared and used for quantification. When the concentration of halogen other than fluorine was less than 1 ppm, no halogen was present and 1 ppm or more was regarded as having halogen.

(6) Haze Measured using a NDH-300A turbidimeter manufactured by Nippon Denshoku Industries Co., Ltd. according to JIS K 7105 “Testing method for optical properties of plastics”.

Example 1
(1) Preparation of coating solution A coating solution 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 copolymerized polyester resin (A) having a number average molecular weight of 19,500 and a softening point of 60 ° C.
300 parts by mass of the obtained copolyester resin (A) and 140 parts by mass of butyl cellosolve were stirred at 160 ° C. for 3 hours to obtain a viscous melt, and 560 parts by mass of water was gradually added to the melt. After 1 hour, a uniform light white solid dispersion having a solid content concentration of 30% was obtained.

(Synthesis of polyurethane resin (A))
100 parts by mass of a polyester diol (OHV: 2000 eq / ton) having a composition of adipic acid // 1.6-hexanediol / neopentyl glycol (molar ratio: 4/2/2/3), and 41.4 xylylene diisocyanate After mixing by mass and reacting at 80 to 90 ° C. for 1 hour under a nitrogen stream, the mixture was cooled to 60 ° C. and dissolved by adding 70 parts by mass of tetrahydrofuran to obtain a urethane prepolymer solution (NCO / OH ratio: 2.2). , Free isocyanate group: 3.30% by mass). Subsequently, the urethane prepolymer solution was brought to 40 ° C., then, 45.5 parts by mass of a 20% by mass aqueous sodium bisulfite solution was added, and the mixture was reacted at 40-50 ° C. for 30 minutes while vigorously stirring. After confirming the disappearance of the free isocyanate group content (in terms of solid content), the aqueous solution of the self-crosslinking polyurethane resin containing an isocyanate group diluted with emulsified water and blocked with sodium bisulfite having a solid content of 20% by mass (A) Got.

  A 30% by mass aqueous dispersion (7.5 parts by mass) of the obtained copolyester resin (A), a self-crosslinking polyurethane resin aqueous solution (A) (11.3 parts by mass), an organotin catalyst ( 0.3 parts by mass), water (39.8 parts by mass) and isopropyl alcohol (37.4 parts by mass) were mixed. Furthermore, as a surfactant <1>, a 10% by mass aqueous solution (0.6 part by mass) of a fluorine compound (polyoxyethylene-2-perfluorohexylethyl ether) having a skeleton having six ethylene oxide groups, particles ( Colloidal silica (average particle size 40 nm) as a 20 mass% aqueous dispersion (2.3 parts by mass) as P1) and dry process silica (average particle size 200 nm, average primary particle size 40 nm) as particles (P2) 3.5 A mass% aqueous dispersion (0.5 parts by mass) was added. Next, the pH of the above mixture is adjusted to 6.2 with a 5% by mass aqueous sodium bicarbonate solution, and the above mixture is microfiltered with a felt type polypropylene filter having a filtration particle size (initial filtration efficiency: 95%) of 10 μm. Was prepared.

(2) Production of Laminated Thermoplastic Resin Film Polyethylene terephthalate (PET) resin pellets containing no particles and having an intrinsic viscosity of 0.62 dl / g as a raw material polymer were dried under reduced pressure (1 Torr) at 135 ° C. for 6 hours. Next, the dried PET resin pellets are supplied to an extruder, and at about 285 ° C., using a stainless sintered filter medium having a filtration particle size (initial filtration efficiency: 95%) of 15 μm, a molten PET resin is obtained. The foreign matter was removed by microfiltration, 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.

The obtained cast film was heated to 95 ° C. with a heated roll group, 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 liquid E 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 a roll coating method. The coating amount was 0.08 g / m ² as the final solid content.

Next, this uniaxially stretched polyester film was guided to a clip-type transverse stretching machine, preheated at 100 ° C., stretched 4.0 times in the transverse direction at 130 ° C., then heat-set at 230 ° C., and then at 200 ° C. The film was relaxed 3% in the transverse direction, and then wound with a film winder to obtain a biaxially stretched polyester film having a thickness of 100 μm.

(Example 2)
A laminated thermoplastic resin film was obtained in the same manner as in Example 1 except that the addition amount of the 10% by mass aqueous solution of the surfactant <1> was changed to 0.3 parts by mass.

(Example 3)
A laminated thermoplastic resin film was obtained in the same manner as in Example 1 except that the addition amount of the 10% by mass aqueous solution of the surfactant <1> was changed to 1.0 part by mass.

Example 4
Surfactant <2> (Co., Ltd.) comprising an addition reaction product of perfluoropropylene polymer (2 and trimer) and polyoxyethylene (number of ethylene oxide units = 8) instead of surfactant <1> A laminated thermoplastic resin film was obtained in the same manner as in Example 2 except that Neogene's (Factent 251) was used.

(Example 5)
Surfactant <3> (Co., Ltd.) comprising an addition reaction product of perfluoropropylene polymer (2 and trimer) and polyoxyethylene (number of ethylene oxide units = 12) instead of surfactant <1> A laminated thermoplastic resin film was obtained in the same manner as in Example 2 except that Neothos' product, “Factent 212MH” was used.

(Example 6)
A laminated thermoplastic resin film was obtained in the same manner as in Example 2 except that the surfactant <1> was further subjected to the purification treatment shown below.
(Surfactant purification)
Isopropyl alcohol (IPA) was added to the surfactant <1> and dissolved by heating in a hot bath at 30 ° C. to prepare an IPA solution of 15% by mass of the surfactant <1>. This solution was filtered with a quantitative filter paper (Advantech Toyo, No. 5C) to remove insolubles and dust in the solution. The obtained filtrate was put in a sealed glass container and allowed to stand in a freezer at 0 ° C. for 24 hours. 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 weight aqueous solution, and used as the pretreated surfactant <1>.

  The surfactant <1> 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.

(Example 7)
As a 30% aqueous dispersion of the copolyester resin (A), 300 parts by mass of the copolyester resin (A) and 250 parts by mass of butyl cellosolve were stirred at 160 ° C. for 3 hours to obtain a viscous melt. In the same manner as in Example 2 except that 450 parts by weight of water was gradually added to the melt and a uniform light white solid content dispersion of 30% obtained after 1 hour was used. A plastic resin film was obtained.

(Example 8)
As a 30% aqueous dispersion of the copolyester resin (A), 300 parts by mass of the copolyester resin (A) and 60 parts by mass of butyl cellosolve are stirred at 160 ° C. for 3 hours to obtain a viscous melt. In the same manner as in Example 2, except that 600 parts by mass of water was gradually added to this melt and a uniform light white solid dispersion having a solid content of 30% obtained after 1 hour was used. A plastic resin film was obtained.

Example 9
A laminated thermoplastic resin film was obtained in the same manner as in Example 2 except that a high-pressure mercury lamp was installed at the outlet of the seventh heat setting zone and the adhesive modified layer was irradiated with ultraviolet rays under the condition of 200 mJ / cm ² . .

(Example 10)
Implemented except using fluorine compound (polyoxyethylene-2-perfluorooctylethyl ether) (surfactant <4>) having 15 ethylene oxide groups in the skeleton instead of surfactant <1> In the same manner as in Example 2, a laminated thermoplastic resin film was obtained.

(Comparative Example 1)
As a 30% aqueous dispersion of the copolyester resin (A), 300 parts by mass of the copolyester resin (A) and 20 parts by mass of butyl cellosolve are stirred at 160 ° C. for 10 hours to obtain a viscous melt. A laminated thermoplastic resin film was prepared in the same manner as in Example 2 except that water was gradually added to this melt and a uniform light white solid content dispersion of 30% obtained after 5 hours was used. Got.

(Comparative Example 2)
A laminated thermoplastic resin film was obtained in the same manner as in Example 1 except that the surfactant was not added.

(Comparative Example 3)
As a 30% aqueous dispersion of the copolyester resin (A), 300 parts by mass of the copolyester resin (A) and 550 parts by mass of butyl cellosolve are stirred at 25 ° C. for 1 hour to obtain a viscous melt. A laminated thermoplastic resin film was obtained in the same manner as in Example 2 except that an aqueous dispersion having a solid content concentration of 30% obtained by adding water to the melt was used.

(Comparative Example 4)
Instead of using surfactant <1>, a fluorine compound (polyoxyethylene-2-perfluorooctylsulfoamidoethyl ether) (surfactant <5>) having 9 ethylene oxide groups in the skeleton was used. Obtained a laminated thermoplastic resin film in the same manner as in Example 1. The surfactant <5> contained a compound having chlorine as a reaction intermediate product. As a result, there was no problem in the adhesion between the laminated film and the functional layer, but a fluorine offset was observed.

  Table 1 shows the evaluation results of the laminated films obtained in each Example and each Comparative Example. In any laminated film, the haze value was 1.5% or less.

  The laminated thermoplastic resin film of the present invention is excellent in adhesion to the functional layer and blocking resistance, and further, there is little transfer to the other surface of the low molecular weight component (fluorine compound) contained in the adhesion modified layer. . Therefore, the laminated thermoplastic resin film of the present invention is suitably applied as a base film of an optical film such as a hard coat film or an infrared absorption film, which is mainly used for display.

Claims (11)

A laminated thermoplastic resin film comprising a thermoplastic resin film and an adhesive modification layer provided on one or both sides thereof,
The adhesive modifying layer is a layer provided by coating an aqueous solution, copolymer polyester resins, polyurethane resins, containing a fluorine-based compound and high boiling solvents, halogen (provided that fluorine except) does not have a,
The high boiling point solvent has a boiling point of 150 ° C. or more and 200 ° C. or less, and its content is 0.005% by mass or more and less than 0.05% by mass with respect to the total mass of the adhesive property modified layer ,
The fluorine-based compound has an average of 6 to 16 ethylene oxide groups and a linear or branched perfluoroalkyl group having 6 to 9 carbon atoms in its molecular structure. The ratio (n / m) to the carbon number (m) of the fluoroalkyl group is 0.8 or more and 2.0 or less,
Laminated thermoplastic film. The laminated thermoplastic resin film according to claim 1, wherein the fluorine-based compound is at least one compound of the following (I) or (II):
(I) an addition reaction product of a perfluoropropylene polymer and polyoxyethylene having an average of 8 to 12 ethylene oxide groups in the molecular structure;
(II) Polyoxyethylene-2-perfluorohexyl ethyl ether or polyoxyethylene-2-perfluorooctyl ethyl ether having an average of 6 to 16 ethylene oxide groups in the molecular structure. The high boiling point solvent is represented by the general formula: R ¹ —O—CH ₂ —Z—CR ³ R ⁴ —O—R ^2.
(Wherein R ^{1 to} R ⁴ are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, provided that at least one of R ¹ and R ² is other than a hydrogen atom. The laminated thermoplastic resin film according to claim 1, which is a compound represented by a single bond, a methylene group or an oxy group (-O-).   The high boiling point solvent is ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol dimethyl ether, ethylene glycol t-butyl ether, 3-methyl 3-methoxybutanol, 3-methoxybutanol, propylene glycol propyl ether, dipropylene glycol monomethyl. The laminated thermoplastic resin film according to claim 1, which is one or more solvents selected from the group consisting of ether, dipropylene glycol monoethyl ether, ethylene glycol monoethyl ether acetate and diethylene glycol monoethyl ether acetate. .   The laminated thermoplastic resin film according to any one of claims 1 to 4, wherein the thermoplastic resin film and / or the adhesion modified layer contains particles.   The laminated thermoplastic resin film according to any one of claims 1 to 4, wherein the thermoplastic resin film contains substantially no particles, and at least one of the adhesive modification layers contains particles.   The laminated thermoplastic resin film according to claim 5, wherein the particles are silica particles.   The laminated thermoplastic resin film according to any one of claims 1 to 7, wherein the haze of the laminated thermoplastic resin film is 1.5% or less.   The laminated thermoplastic resin film according to any one of claims 1 to 8, which is used as a base film for an optical functional film or an optical functional sheet.   The laminated thermoplastic resin film according to claim 9, wherein the optical functional film or the optical functional sheet is a prism sheet. The laminated thermoplastic resin film according to any one of claims 1 to 10, wherein at least one of the adhesive modified layers has been subjected to ultraviolet irradiation of 100 mJ / cm ² or more and less than 300 mJ / cm ² .