JP2008096499A - Functional thermoplastic resin sheet having uneven surface, its manufacturing method and transfer film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a functional thermoplastic resin sheet having an uneven surface which is manufactured by forming a functional thin film on the uneven surface of the thermoplastic resin sheet having the uneven surface by following the uneven surface with high adhesion and further to provide its manufacturing method and a transfer film. <P>SOLUTION: The functional thermoplastic resin sheet includes the thin film of at least one layer formed on the uneven surface of the thermoplastic resin sheet having the uneven surface by a transfer method. The manufacturing method includes transferring, using a transfer film with the thin film of at lest one layer formed on a surface of a substrate film, the thin film to the uneven surface of a thermoplastic resin sheet having the uneven surface. When glass transition temperature of the thermoplastic resin sheet is denoted as Tg, a surface temperature of the thermoplastic resin sheet is in a range of not lower than (Tg-10°C) and not higher than (Tg+70°C) and the substrate film having a softening point lower than the surface temperature of the thermoplastic resin sheet is used. The transfer film uses a specific film as the substrate film. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a functional thermoplastic resin sheet having an uneven surface, a method for producing the same, and a transfer film.

  As a method for imparting functionality to the thermoplastic resin sheet, when the thermoplastic resin sheet was extruded, it was extruded using a transfer film in which a thin film having various functionalities was formed on the surface of the base film. Forming the thin film on the surface of the sheet by a transfer method is a well-known technique. For example, Patent Document 1 discloses a method for producing a synthetic resin decorative material in which a thin film having antistatic properties is formed on the surface of a thermoplastic resin sheet by a transfer method. Patent Documents 2, 3 and 4 disclose a method for producing an extruded composite sheet in which a thin film having surface protective property, surface antireflection property or antistatic property is formed on a surface of a thermoplastic resin sheet by a transfer method. Yes. In these manufacturing methods, since the surface of the extruded sheet is smooth, it is easy to form a functional thin film on the surface by a transfer method.

  However, if the surface of the extruded sheet is embossed or matte, or has an optical design such as a lenticular lens or prism, that is, if the extruded sheet has an uneven surface, the surface In addition, when a thin film having various functions is formed by a transfer method, the transfer film cannot follow the uneven surface of the sheet, so that the transfer film comes into point contact with the convex part of the sheet, and air enters the concave part. There was a problem that the adhesion of the thin film was lowered, and as a result, sufficient functionality could not be imparted to the sheet.

Patent Document 1 discloses a technique for forming a concavo-convex pattern on a transferred synthetic resin coating layer by pressing an embossing roll or an embossing plate when a transfer film is pressure-bonded. A method for transferring a thin film to a thermoplastic resin sheet having the above has not been known so far.
JP-A-5-162230 JP 2004-90281 A JP 2005-193471 A JP 2005-193514 A

  Under the circumstances described above, the problem to be solved by the present invention is that a thin film having functionality is formed on the uneven surface of a thermoplastic resin sheet having an uneven surface with high adhesion following the uneven surface. Another object of the present invention is to provide a functional thermoplastic resin sheet having an uneven surface, a method for producing the same, and a transfer film.

  As a result of various studies, the inventors have used a transfer film in which a thin film having functionality is formed on the surface of a base film, and transfers the thin film to the uneven surface of a thermoplastic resin sheet having an uneven surface. In addition, if a base film having a predetermined softening point is used by adjusting the surface temperature of the thermoplastic resin sheet within a predetermined temperature range, the thin film can be formed with high adhesion while following the uneven surface. And the present invention was completed.

  That is, the present invention provides a functional thermoplastic resin sheet having an uneven surface, wherein the thermoplastic resin sheet having an uneven surface has at least one layer of thin film formed on the uneven surface by a transfer method. . The thermoplastic resin constituting the sheet is preferably selected from the group consisting of amorphous resins such as polycarbonate resins, (meth) acrylic resins, styrene resins, (meth) acryl-styrene copolymers, and cyclic olefin resins. Selected. The resin constituting at least one layer of the thin film can have, for example, ultraviolet absorptivity. At least one layer of the thin film can contain, for example, an antistatic agent, a fluorescent brightening agent, fine particles, and the like.

  The present invention also provides a light diffusion plate for a liquid crystal display device, wherein the functional thermoplastic resin sheet is used in a backlight unit of the liquid crystal display device.

  Furthermore, the present invention provides a method for producing the functional thermoplastic resin sheet. This manufacturing method uses the transfer film in which at least one layer of thin film is formed on the surface of a base film, and transfers the thin film to the uneven surface of a thermoplastic resin sheet having an uneven surface. When the glass transition temperature of the sheet is Tg, the surface temperature of the thermoplastic resin sheet is in the range of (Tg−10 ° C.) to (Tg + 70 ° C.) and lower than the surface temperature of the thermoplastic resin sheet. A base film having a softening point is used.

  Furthermore, this invention provides the transfer film excellent in the transferability to the uneven | corrugated surface used for the said manufacturing method. This transfer film is a transfer film in which a thin film is formed on the surface of a base film, and as the base film, a low density polyethylene film, a high density polyethylene film, a linear low density polyethylene film, a biaxially stretched polypropylene film It is characterized by using at least one film selected from (OPP film) and unstretched polypropylene film (CPP film).

  According to the present invention, a thin film having functionality can be formed on the uneven surface of a thermoplastic resin sheet having an uneven surface with high adhesion while following the uneven surface. Therefore, for example, even if the surface of the thermoplastic resin sheet is embossed or matte, or has an optical system design such as a lenticular lens or prism, various functions can be applied to such a thermoplastic resin sheet. (For example, antistatic properties, light resistance, super water repellency, super hydrophilicity, antifogging properties, low reflectivity, antireflection properties, etc.) can be imparted.

≪Functional thermoplastic resin sheet with uneven surface≫
The functional thermoplastic resin sheet having an uneven surface according to the present invention (hereinafter sometimes referred to as “functional thermoplastic resin sheet of the present invention”) is transferred onto the uneven surface of the thermoplastic resin sheet having an uneven surface by a transfer method. It has at least one thin film formed. Here, “uneven surface” means that either one or both of the front surface and the back surface of the thermoplastic resin sheet are not smooth but have a three-dimensional shape formed intentionally. The uneven surface is not particularly limited, and examples thereof include an embossed tone, a mat (template glass) tone, and an optical system design such as a lenticular lens and a prism. Moreover, the thin film of at least one layer means that the case where the thin film is a single layer and the case where the thin film is a plurality of layers are included.

  When the uneven surface is embossed or matt (template glass), the degree of the uneven surface is represented by the centerline average roughness defined in Annex 2 of JIS B0601: 2001. However, the cut-off value when determining the center line average roughness is 0.8 mm, and the evaluation length is 4 mm. The center line average roughness can be determined by, for example, a surface roughness meter. In this case, the center line average roughness of the irregular surface is preferably in the range of 0.5 to 15 μm, more preferably 1 to 10 μm. When the center line average roughness of the uneven surface is less than 0.5 μm, the design may be lacking. Conversely, if the center line average roughness of the uneven surface exceeds 15 μm, it may be difficult to transfer the thin film to the deepest portion of the concave portion.

  When the uneven surface is an optical system design such as a lenticular lens or a prism, the degree of the uneven surface is expressed by the pitch and depth of the same shape in the optical system design. For example, when the uneven surface is in the shape of a lenticular lens or a prism, the pitch is preferably 30 to 500 μm, more preferably 50 to 300 μm, and the depth is preferably 10 to 300 μm, more preferably It is in the range of 20 to 200 μm. Note that the pitch and depth of the same shape can be obtained by, for example, a non-contact level difference measuring machine, a laser confocal microscope, or the like. In particular, when a light diffusion plate is produced by transferring a functional thin film to a thermoplastic resin sheet having an optical system design, if the pitch is out of the above range, necessary optical performance may not be obtained. Further, if the depth is less than 10 μm, necessary optical performance may not be obtained. On the contrary, when the depth exceeds 300 μm, it may be difficult to transfer the thin film to the deepest portion corresponding to the concave portion. Note that the shape of the lenticular lens may be either convex or concave, or a combination thereof.

  The functional thermoplastic resin sheet of the present invention has, for example, antistatic properties, light resistance, super water repellency, super hydrophilicity, antifogging properties, low reflectivity, antireflection properties and the like. Basically, the property is derived from the thin film transferred to the uneven surface. That is, an additive exhibiting these functions may be contained in the thin film transferred to the uneven surface, or the thin film may be composed of a thermoplastic resin having these functions.

<Thermoplastic resin sheet>
The material of the thermoplastic resin sheet is not particularly limited, but any thermoplastic resin that can be processed into a plate shape with unevenness can be applied. Among them, polycarbonate resins such as polycarbonate (PC); (meth) acrylic resins such as polymethyl methacrylate (PMMA); styrene resins such as polystyrene (PS); (meth) acrylic such as polymethacrylstyrene (MS) An amorphous resin such as a styrene copolymer; a cyclic olefin-based resin such as a cyclic olefin polymer (COP) or a cyclic olefin copolymer (COC); The thermoplastic resin sheet may be formed of a single material or two or more kinds of materials, and may be formed of a single layer or a plurality of layers. Good.

  The “amorphous resin” means a thermoplastic resin that does not have a clear melting point of the resin when DSC is measured by a method based on the DSC measurement method (heat flow rate DSC) defined in JIS K7121.

  For example, an additive such as a stabilizer, an antioxidant, a plasticizer, a dispersant, and a fluorescent brightening agent may be blended in the thermoplastic resin sheet. What is necessary is just to adjust suitably the compounding quantity of these additives according to the kind etc., and it is not specifically limited.

  The thickness of the thermoplastic resin sheet is preferably 0.5 mm or more and 5 mm or less, more preferably 0.8 mm or more and 3 mm or less. If the thickness of the thermoplastic resin sheet is less than 0.5 mm, the mechanical strength may decrease. On the other hand, when the thickness of the thermoplastic resin sheet exceeds 5 mm, for example, when used as a light diffusion plate for a liquid crystal display device, the amount of light passing through the sheet may decrease and the luminance may decrease.

  For example, when the thermoplastic resin sheet is used as a light diffusion plate for a liquid crystal display device, it can contain fine particles in order to diffuse light from the light source uniformly and satisfactorily. It is preferable that the fine particles contained in the thermoplastic resin sheet are substantially uniformly dispersed. Moreover, when the thermoplastic resin sheet is comprised from several layers, the microparticles | fine-particles contained in a thermoplastic resin sheet may be contained in which layer.

  Examples of the material of the fine particles include (meth) acrylic resins, styrene resins, polyurethane resins, polyester resins, silicone resins, fluorine resins, synthetic resins such as copolymers thereof, glass, smectite, and kaori. And clay compounds such as knight; inorganic oxides such as silica and alumina; and the like. Of these materials, (meth) acrylic resins, styrene resins, silicone resins, and silica are particularly suitable.

  The average particle diameter of the fine particles is preferably 0.1 μm or more and 30 μm or less, more preferably 0.5 μm or more and 25 μm or less, and further preferably 1 μm or more and 20 μm or less. If the average particle size is less than 0.1 μm, the light incident on the thin film may not be sufficiently diffused. On the other hand, when the average particle diameter exceeds 30 μm, the amount of light passing through the thin film is reduced, and the luminance may be lowered. The average particle diameter of each fine particle is a value obtained by simply averaging the particle diameter of 100 arbitrary fine particles observed with a microscope. When each fine particle is irregularly shaped, the average of the maximum diameter and the minimum diameter is defined as the particle diameter.

  Since the shape of the fine particles is the same as that of the fine particles to be contained in the thin film described below, the description thereof is omitted here. However, the amount of fine particles used is preferably 0.1 parts by mass or more and 20 parts by mass or less, more preferably 0.2 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the thermoplastic resin constituting the sheet. It is. If the amount used is less than 0.1 parts by mass, the light incident on the sheet may not be sufficiently diffused. On the other hand, when the amount used exceeds 20 parts by mass, it may be difficult to extrude the sheet, or the amount of light passing through the sheet may decrease and the luminance may decrease.

<Thin film>
In the functional thermoplastic resin sheet of the present invention, the thin film is formed on one side or both sides of the thermoplastic resin sheet. The thin film may be formed of a single material or may be formed of two or more materials, and may be formed of a single layer or a plurality of layers. The thickness of the thin film (the thickness of each layer when the thin film is plural) is preferably 0.01 μm or more and 30 μm or less, more preferably 0.05 μm or more and 20 μm or less, and further preferably 0.1 μm or more and 10 μm or less. It is. If the thickness of the thin film is less than 0.01 μm, the effect of exhibiting various functions may be small, and it may be difficult to form the thin film uniformly. On the other hand, when the thickness of the thin film exceeds 30 μm, when a material different from the thermoplastic resin sheet is used, warpage due to a difference in thermal shrinkage or a difference in water absorption may occur. In addition, the thickness of a thin film is the value measured by the method described in the Example.

  The material constituting the thin film is not particularly limited, and examples thereof include (meth) acrylic resins, saturated polyester resins, epoxy resins, and silicone resins. These resins may be used alone or in combination of two or more. Of these resins, a (meth) acrylic resin is preferable from the viewpoint of easily imparting various functions.

  A functional group and a sensitizer can be added to the resin constituting the thin film and its blend, and cured by various means after transfer. Although it does not specifically limit as a functional group or a sensitizer, Specifically, for example, a hydroxyl group and polyfunctional isocyanate (including blocked isocyanate), a vinyl group and a sensitizer or peroxide, and a hydroxyl group Examples thereof include polyfunctional acid anhydrides, carboxylic acids and polyfunctional epoxy groups, hydroxyl groups and epoxy groups, and carboxylic acids and oxazoline compounds. These combinations may be selected according to the target function.

  Examples of the monomer constituting the (meth) acrylic resin include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, cyclohexyl (meth) acrylate, phenyl (meth) acrylate, and benzyl (meth ) Acrylate, 2-ethylhexyl (meth) acrylate, and (meth) acrylic acid esters such as 2-hydroxyethyl (meth) acrylate. These monomers may be used alone or in combination of two or more.

  In addition to the above-described monomers, for example, unsaturated acids such as (meth) acrylic acid; styrene, butadiene, isoprene, α-methylstyrene, (meth) acrylonitrile, Maleic anhydride, phenylmaleimide, cyclohexylmaleimide and the like may be copolymerized. These monomers may be used alone or in combination of two or more.

  The (meth) acrylic resin may have a crosslinked structure. Examples of the crosslinking agent include isocyanate compounds (including blocked isocyanates); epoxy compounds; aziridin compounds; oxazoline compounds; polyfunctional acid anhydrides; These crosslinking agents may be used alone or in combination of two or more. Of these crosslinking agents, isocyanate compounds are particularly suitable.

  In polymerization of the (meth) acrylic resin, for example, a monomer having antistatic properties or a monomer having ultraviolet absorbing properties can be copolymerized. In addition, as a monomer which has ultraviolet absorptivity, for example, an ultraviolet absorptive monomer as described in Japanese Patent No. 29744943, Japanese Patent Application Laid-Open No. 2003-268048, Japanese Patent Application Laid-Open No. 2006-89535, and the like is used. It is preferable to use it. In addition, various additives such as a polymerization retarder, a chain transfer agent, a polymerization accelerator, an antifoaming agent, a leveling agent, a release agent, and a surfactant may be mixed in the polymerization system as necessary. .

  A method for polymerizing the above monomers may be a conventionally known polymerization method, and is not particularly limited. Examples thereof include bulk polymerization, solution polymerization, emulsion polymerization, suspension polymerization, and dispersion polymerization. It is done. Of these polymerization methods, solution polymerization using a solvent having good solubility in additives such as antistatic agents and ultraviolet absorbers is particularly suitable.

  In the functional thermoplastic resin sheet of the present invention, the thin film has additives such as an antistatic agent, an ultraviolet absorber, a fluorescent whitening agent, so that the sheet exhibits various functionalities. It contains fine particles or is made of a thermoplastic resin that exhibits these functionalities. For example, if at least one layer of a thin film is formed using an ultraviolet-absorbing acrylic resin (for example, Halus Hybrid UV-G series manufactured by Nippon Shokubai Co., Ltd.), light resistance is imparted to the thermoplastic resin sheet. be able to.

  Moreover, you may mix | blend additives, such as a stabilizer, antioxidant, a plasticizer, a dispersing agent, with a thin film, for example. What is necessary is just to adjust suitably the compounding quantity of these additives according to the kind etc., and it is not specifically limited.

<Antistatic agent>
In the functional thermoplastic resin sheet of the present invention, at least one layer of the thin film can contain an antistatic agent. Here, when the thin film is a single layer, at least one layer of the thin films means that thin film, and when the thin film is a plurality of layers, it means at least one thin film among the plurality of thin films. When an antistatic agent is contained in at least one layer of the thin film, the functional thermoplastic resin sheet has a function of preventing adhesion of dust existing in the air or preventing malfunction of the device due to static electricity. .

  As the antistatic agent, any known antistatic agent may be used, and is not particularly limited. For example, when a functional thermoplastic resin sheet is used as a light diffusion plate for a liquid crystal display device, Inorganic compound-based antistatic agents are not preferred because they are difficult to transmit light and may cause light loss. Therefore, it is preferable to use a surfactant or a conductive resin as an organic antistatic agent that does not cause light loss.

  Surfactants that can be used as antistatic agents include, for example, alkyl sulfonic acids, alkyl benzene sulfonic acids, olefinic sulfates such as Li, Na, Ca, Mg, and Zn salts thereof or metal salts thereof, higher alcohols, and the like. Anionic surfactants such as phosphate esters; Cationic surfactants such as tertiary amines, quaternary ammonium salts, cationic acrylic ester derivatives and cationic vinyl ether derivatives; amphoteric salts of alkylamine betaines; Amphoteric surfactants such as amphoteric salts of carboxylic acid or alanine sulfonate, amphoteric salts of alkylimidazolines; fatty acid polyhydric alcohol esters, non-ionic surfactants such as polyoxyethylene adducts of alkyl (amine), etc. Can be mentioned. Examples of the conductive resin that can be used as the antistatic agent include polyvinyl benzyl type cationic resins and polyacrylic acid type cationic resins. These antistatic agents may be used alone or in combination of two or more. Of these antistatic agents, cationic surfactants such as tertiary amines and quaternary ammonium salts are preferred.

  The amount of the antistatic agent used is preferably 0.1 parts by mass or more and 100 parts by mass or less, more preferably 0.2 parts by mass or more, with respect to 100 parts by mass of the thermoplastic resin constituting the thin film containing the antistatic agent. It is 70 mass parts or less, More preferably, it is 0.3 mass part or more and 50 mass parts or less. If the amount used is less than 0.1 parts by mass, the effect of preventing the adhesion of dust and the effect of preventing malfunction of the apparatus may be small. On the other hand, when the amount used exceeds 100 parts by mass, the effect of preventing the adhesion of dust and the effect of preventing the malfunction of the apparatus may be saturated.

As described above, the functional thermoplastic resin sheet of the present invention can prevent the adhesion of dust existing in the air or the static electricity of the device when at least one layer of the thin film contains an antistatic agent. Shows functionality to prevent malfunctions. Specifically, the surface resistance value on the thin film side containing the antistatic agent is preferably 10 ¹² Ω or less, more preferably 10 ¹¹ Ω or less, and further preferably 10 ¹⁰ Ω or less. When the surface specific resistance value exceeds 10 ¹² Ω, it may not be possible to prevent dust adhesion and malfunction of the apparatus. Here, the surface resistance value is a value measured according to JIS K6911.

<Ultraviolet absorber>
In the functional thermoplastic resin sheet of the present invention, at least one of the thin films can contain an ultraviolet absorber. Here, when the thin film is a single layer, at least one layer of the thin films means that thin film, and when the thin film is a plurality of layers, it means at least one thin film among the plurality of thin films. In addition, the thin film containing an ultraviolet absorber is preferably formed on the surface on the side where the functional thermoplastic resin sheet receives light. This is because the purpose is to prevent the influence of light. When an ultraviolet absorber is contained in at least one of the thin films, it has high light resistance. For example, when a functional thermoplastic resin sheet is used as a light diffusion plate for a liquid crystal display device, The image can be stabilized over a long period of time and the display quality can be improved.

  As the ultraviolet absorber, any conventionally known ultraviolet absorber may be used, and is not particularly limited. For example, salicylic acid phenyl ester ultraviolet absorber, benzophenone ultraviolet absorber, triazine ultraviolet absorber, Low molecular weight UV absorbers such as benzotriazole type UV absorbers, cyclic imino ester type UV absorbers, hybrid UV absorbers that have both hindered phenol and hindered amine structures in the molecule, and these low molecular UV absorbers Examples thereof include a polymer type ultraviolet absorber in which the agent is suspended from the polymer. These ultraviolet absorbers may be used alone or in combination of two or more. It is also preferable to use a hindered amine UV stabilizer.

  Specific examples of salicylic acid phenyl ester ultraviolet absorbers include phenyl salicylate, p-tert-butylphenyl salicylate, and p-octylphenyl salicylate.

  Specific examples of the benzophenone ultraviolet absorber include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, and 2-hydroxy-4-benzyloxybenzophenone. 2-hydroxy-4-methoxy-5-sulfoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfoxytrihydridolate benzophenone, 2,2′-dihydroxy-4-methoxybenzophenone, 2,2 ′, 4 , 4′-tetrahydroxybenzophenone, 2,2′-dihydroxy-4,4′-dimethoxybenzophenone, 2,2′-dihydroxy-4,4′-dimethoxy-5-sodiumsulfoxybenzophenone, bis (5-benzoyl) -4-hydroxy-2-me Kishifeniru) methane, 2-hydroxy -4-n-dodecyloxy benzophenone, 2-hydroxy-4-methoxy-2'-carboxy benzophenone.

  Specific examples of the triazine ultraviolet absorber include 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5-hexyloxyphenol.

  Specific examples of the benzotriazole ultraviolet absorber include 2- (2-hydroxy-5-methylphenyl) benzotriazole, 2- (2-hydroxy-5-t-octylphenyl) benzotriazole, 2- (2-hydroxy-3,5-dicumylphenyl) phenylbenzotriazole, 2- (2-hydroxy-3-t-butyl-5-methylphenyl) -5-chlorobenzotriazole, 2,2′-methylenebis [4 -(1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol], 2- (2-hydroxy-3,5-di-t-butylphenyl) benzotriazole 2- (2-hydroxy-3,5-di-t-butylphenyl) -5-chlorobenzotriazole, 2- (2-hydroxy-3 5-di-t-amylphenyl) benzotriazole, 2- (2-hydroxy-5-t-octylphenyl) benzotriazole, 2- (2-hydroxy-5-t-butylphenyl) benzotriazole, 2- (2 -Hydroxy-4-octoxyphenyl) benzotriazole, 2,2′-methylenebis (4-cumyl-6-benzotriazolephenyl), 2,2′-p-phenylenebis (1,3-benzoxazin-4-one ), 2- [2-hydroxy-3- (3,4,5,6-tetrahydrophthalimidomethyl) -5-methylphenyl] benzotriazole and the like.

  Specific examples of the cyclic imino ester type ultraviolet absorber include 2,2′-p-phenylenebis (3,1-benzoxazin-4-one), 2,2 ′-(4,4′-). And diphenylene) bis (3,1-benzoxazin-4-one) and 2,2 ′-(2,6-naphthalene) bis (3,1-benzoxazin-4-one).

  Specific examples of the hybrid ultraviolet absorber having both a hindered phenol structure and a hindered amine structure in the molecule include 2- (3,5-di-t-butyl-4-hydroxybenzyl) -2. -Bis (1,2,2,6,6-pentamethyl-4-piperidyl) -n-butylmalonate, 1- [2- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl Oxy] ethyl] -4- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy] -2,2,6,6-tetramethylpiperidine and the like.

  Examples of the polymer type ultraviolet absorber in which the low molecular weight ultraviolet absorbing functional group is suspended from the polymer include, for example, Japanese Patent No. 2979443, Japanese Patent Application Laid-Open No. 2003-268048, Japanese Patent Application Laid-Open No. 2006-89535, and the like. Examples thereof include polymer ultraviolet absorbers as described, and specific examples include Halus Hybrid UV-G series manufactured by Nippon Shokubai Co., Ltd.

  Among these ultraviolet absorbers, 2-hydroxy-4-n-octoxybenzophenone, 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5-hexyloxyphenol, 2- (2-hydroxy-5-t-octylphenyl) benzotriazole, 2- (2-hydroxy-3,5-dicumylphenyl) phenylbenzotriazole, 2- (2-hydroxy-3-tert-butyl-5-methyl) Phenyl) -5-chlorobenzotriazole, 2,2′-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol], 2,2 '-P-phenylenebis (3,1-benzoxazin-4-one), Hals hybrid UV-G series manufactured by Nippon Shokubai Co., Ltd. is particularly suitable.

  Specific examples of hindered amine ultraviolet stabilizers include bis (2,2,6,6-) tetramethyl-4-piperidyl) sebacate and bis (1,2,2,6,6-pentamethyl-4). -Piperidyl) sebacate and the like.

  The amount of the ultraviolet absorber used is preferably 0.5 parts by mass or more and 50 parts by mass or less, more preferably 0.8 parts by mass or more, with respect to 100 parts by mass of the thermoplastic resin constituting the thin film containing it. It is 40 parts by mass or less, more preferably 1 part by mass or more and 30 parts by mass or less. If the amount used is less than 0.5 parts by mass, the effect of preventing the influence of light may be small. Conversely, when the amount used exceeds 50 parts by mass, the effect of preventing the influence of light may be saturated.

As described above, the functional thermoplastic resin sheet of the present invention exhibits the functionality of preventing the influence of light when at least one of the thin films contains an ultraviolet absorber. Specifically, when the ultraviolet ray having an intensity of 100 mW / cm ² is irradiated on the thin film side containing the ultraviolet absorber for 50 hours, the formula: ΔYI = yellowness after ultraviolet irradiation (YI) −yellowness before ultraviolet irradiation (YI ) Is preferably 5 or less, more preferably 4.5 or less, and even more preferably 4 or less. The yellowness (YI) is a value measured according to JIS Z8722.

<Fluorescent brightener>
In the functional thermoplastic resin sheet of the present invention, at least one of the thin films can contain a fluorescent brightening agent. Here, when the thin film is a single layer, at least one layer of the thin films means that thin film, and when the thin film is a plurality of layers, it means at least one thin film among the plurality of thin films. The fluorescent whitening agent has an action of absorbing ultraviolet energy contained in light and converting this energy into visible light. Therefore, when a thin film containing a fluorescent brightening agent is provided, loss of light due to light refraction and absorption can be compensated, and light uniformity and brightness are improved. These functionalities are particularly useful when, for example, a functional thermoplastic resin sheet is used as a light diffusion plate for a liquid crystal display device.

  As the fluorescent brightening agent, any conventionally known fluorescent brightening agent may be used, and is not particularly limited. For example, oxazole fluorescent brightening agent, coumarin fluorescent brightening agent, stilbene fluorescent brightening agent may be used. Examples thereof include a whitening agent, an imidazole fluorescent whitening agent, a triazole fluorescent whitening agent, a naphthalimide fluorescent whitening agent, and a rhodamine fluorescent whitening agent. These fluorescent brighteners may be used alone or in combination of two or more. Of these fluorescent brighteners, oxazole fluorescent brighteners and coumarin fluorescent brighteners are particularly suitable.

  The amount of the fluorescent whitening agent used is preferably 0.0005 parts by mass or more and 50 parts by mass or less, more preferably 0.001 parts by mass or more and 30 parts by mass with respect to 100 parts by mass of the resin constituting the thin film containing it. Or less. If the amount used is less than 0.0005 parts by mass, the effect of improving the uniformity and brightness of light may be small. On the other hand, if the amount used exceeds 50 parts by mass, the light uniformity may be impaired, and the mechanical strength of the thin film may be impaired. In addition, a fluorescent whitening agent that is more expensive than necessary is used. As a result, the manufacturing cost may increase.

<Fine particles>
In the functional thermoplastic resin sheet of the present invention, at least one of the thin films can contain fine particles. Here, when the thin film is a single layer, at least one layer of the thin films means that thin film, and when the thin film is a plurality of layers, it means at least one thin film among the plurality of thin films. The fine particles contained in the thin film are preferably dispersed substantially uniformly. Since the fine particles diffuse light uniformly and satisfactorily, the light uniformity and brightness are improved. These functionalities are particularly useful when, for example, a functional thermoplastic resin sheet is used as a light diffusion plate for a liquid crystal display device.

  Examples of the material of the fine particles include (meth) acrylic resins, styrene resins, polyurethane resins, polyester resins, silicone resins, fluorine resins, synthetic resins such as copolymers thereof, glass, smectite, and kaori. And clay compounds such as knight; inorganic oxides such as silica and alumina; and the like. Of these materials, (meth) acrylic resins, styrene resins, (meth) acryl-styrene copolymers, silicone resins, and silica are particularly suitable.

  The fine particles may be formed of a single material or two or more kinds of materials, and may be formed of two or more kinds of fine particles having different materials even if they are formed of the same kind of fine particles. It may be configured.

  Examples of the shape of the fine particles include a spherical shape, a flat shape, an ellipsoidal shape, a polygonal shape, and a plate shape. The fine particles having these shapes may be used alone or in combination of two or more. Among the fine particles having these shapes, spherical particles are suitable, but they have a light diffusibility stronger than spherical particles, and high luminance can be obtained with a small amount of addition, so that they are flat, elliptical, In some cases, irregularly shaped particles such as polygonal shapes and plate shapes are suitable.

  The average particle diameter of the fine particles is preferably 0.1 μm or more and 30 μm or less, more preferably 0.5 μm or more and 25 μm or less, and further preferably 1 μm or more and 20 μm or less. If the average particle size is less than 0.1 μm, the light incident on the thin film may not be sufficiently diffused. On the other hand, when the average particle diameter exceeds 30 μm, the amount of light passing through the thin film is reduced, and the luminance may be lowered. The average particle diameter of each fine particle is a value obtained by simply averaging the particle diameter of 100 arbitrary fine particles observed with a microscope. When each fine particle is irregularly shaped, the average of the maximum diameter and the minimum diameter is defined as the particle diameter.

  The amount of the fine particles used is preferably 1 part by mass or more and 200 parts by mass or less, more preferably 5 parts by mass or more and 150 parts by mass or less, and further preferably 10 parts by mass or more with respect to 100 parts by mass of the resin containing the fine particles. , 100 parts by mass or less. If the amount used is less than 1 part by mass, the light incident on the thin film may not be sufficiently diffused. On the other hand, if the amount used exceeds 200 parts by mass, it may be difficult to form a thin film, or the amount of light passing through the thin film may decrease, resulting in a decrease in luminance.

<Use of functional thermoplastic resin sheet>
The functional thermoplastic resin sheet of the present invention is excellent in light when a thin film is composed of, for example, an ultraviolet-absorbing thermoplastic resin, and the thin film contains an antistatic agent, a fluorescent brightening agent, fine particles, and the like. Since it exhibits diffusibility, it can be used as a light diffusion plate for liquid crystal display devices.

  The light diffusing plate for a liquid crystal display device according to the present invention is characterized in that the functional thermoplastic resin sheet as described above is used for a backlight unit of a liquid crystal display device. The light diffusion plate for a liquid crystal display device of the present invention can be used as a light diffusion plate of a conventionally known direct type backlight unit or sidelight type backlight unit in a liquid crystal display device. Since it can be stabilized over a long period of time and its display quality can be improved, a direct type backlight unit is particularly suitable for large liquid crystal display devices used for liquid crystal displays exceeding 15 inches and liquid crystal displays of desktop personal computers. It is preferable to use it as a light diffusion plate.

≪Transfer film≫
The transfer film of the present invention is a transfer film in which a thin film is formed on the surface of a base film, and the base film includes a low density polyethylene film, a high density polyethylene film, a linear low density polyethylene film, and biaxial stretching. It is characterized by using at least one film selected from a polypropylene film (OPP film) and an unstretched polypropylene film (CPP film).

  Since the transfer film of the present invention is excellent in transferability to an uneven surface, it is suitable for the method for producing a functional thermoplastic resin sheet described below.

<Preparation of transfer film>
In order to transfer a thin film to a thermoplastic resin sheet having an uneven surface, first, a resin constituting the thin film and a desired additive such as an antistatic agent or an ultraviolet absorber are dissolved or dispersed in an organic solvent, A resin mixed solution is prepared, and then the resin mixed solution is applied to the surface of the base film and dried to prepare a transfer film in which a thin film is formed on the surface of the base film. In addition, what is necessary is just to repeat the process of apply | coating the resin liquid mixture corresponding to each thin film to the surface of a base film, and drying, when a thin film is a multiple layer.

  Examples of the base film include a low density polyethylene film, a high density polyethylene film, a linear low density polyethylene film, a biaxially stretched polypropylene film (OPP film), and an unstretched polypropylene film (CPP film). Among these films, a high density polyethylene film and a biaxially stretched polypropylene film are suitable.

  The base film may be mixed with, for example, a coating-type release agent or a kneading-type release agent as long as the gist of the present invention is not impaired.

  As described above, when a thin film is transferred to a thermoplastic resin sheet having an uneven surface, when the glass transition temperature of the thermoplastic resin sheet is Tg, the surface temperature of the thermoplastic resin sheet is (Tg-10). ° C) to (Tg + 70 ° C), and it is necessary to use a base film having a softening point lower than the surface temperature of the thermoplastic resin sheet. Therefore, the base film used for the transfer film may be appropriately selected according to the type of thermoplastic resin constituting the sheet.

  The thickness of the base film is preferably 5 μm or more and 100 μm or less, more preferably 10 μm or more and 80 μm or less, and further preferably 15 μm or more and 60 μm or less. If the thickness of the base film is less than 5 μm, the base film may have insufficient tensile strength and may be broken during press bonding. On the other hand, when the thickness of the base film exceeds 100 μm, not only the cost is disadvantageous, but also the pressure bonding of the roll is not uniform, and the transferred thin film may be uneven.

  The organic solvent used in preparing the resin mixed solution may be appropriately selected according to the type of resin or additive, and is not particularly limited. For example, an aromatic solvent such as benzene, toluene, xylene, chlorobenzene, etc. Group solvents; ether solvents such as 1,4-dioxane and tetrahydrofuran; ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone; ester solvents such as ethyl acetate and butyl acetate; alcohols such as methanol, ethanol, isopropanol and butanol Solvent; water; and the like. These solvents may be used alone or in combination of two or more.

  In order to apply the resin mixed solution to the base film, a conventionally known thin film forming method may be adopted, and it is not particularly limited. For example, application by brush, spray coating method, roll coating, bar coating method , T-die coating method, roll reverse coating method, applicator coating method, spin coating method, dip coating method, flow coating method, gravure coating method, MOCVD method, CVD method, sputtering method and the like.

  A method of drying after applying the resin mixed solution to the base film is not particularly limited as long as a conventionally known drying method is adopted. For example, a natural drying method, an air drying method, a hot air, Examples include a drying method and infrared irradiation. The drying temperature is usually in the range of room temperature to about 80 ° C. The drying time is usually about 1 minute to 24 hours.

≪Method for producing functional thermoplastic resin sheet≫
The method for producing a functional thermoplastic resin sheet according to the present invention (hereinafter sometimes referred to as “the production method of the present invention”) uses a transfer film in which at least one layer of thin film is formed on the surface of a substrate film. When the thin film is transferred to the concavo-convex surface of a thermoplastic resin sheet having a surface, when the glass transition temperature of the thermoplastic resin sheet is Tg, the surface temperature of the thermoplastic resin sheet is (Tg-10 ° C.) As described above, a base film having a softening point within the range of (Tg + 70 ° C.) or lower and lower than the surface temperature of the thermoplastic resin sheet is used. Here, the glass transition temperature (Tg) of the thermoplastic resin sheet is a value obtained by DSC measurement by a method based on the DSC measurement method (thermal flow rate DSC) defined in JIS K7121. In addition, the softening point of the base film is the higher of the glass transition temperature (Tg) and the melting point (Tm) measured by DSC measurement according to the DSC measurement method (heat flow rate DSC) defined in JIS K7121. It means temperature. Furthermore, the surface temperature of the thermoplastic resin sheet can be measured with a radiation thermometer.

<Manufacture of functional thermoplastic resin sheet>
The functional thermoplastic resin sheet can be produced by pressing the transfer film on the uneven surface of the thermoplastic resin sheet and transferring the thin film from the transfer sheet to the thermoplastic resin sheet. For the transfer of the thin film, for example, a thermoplastic resin sheet that has been extruded in advance may be heated and the transfer film may be pressure-bonded at a predetermined temperature. However, in consideration of production efficiency, the thermoplastic resin sheet is extruded. At this time, it is preferable to pressure-bond the transfer film in-line.

  A conventionally known sheet extruder may be used for extrusion molding of the thermoplastic resin sheet, and a conventionally known pressure laminating apparatus may be employed for pressure bonding of the transfer sheet. However, it is preferable to use a relatively soft roll such as a rubber-covered roll instead of a hard roll as the pressure-bonding roll. In addition, since the pressure laminating apparatus needs to extrude the thermoplastic resin sheet and press the transfer film at a predetermined temperature, it may be attached at a position where the surface temperature of the extruded sheet becomes a predetermined temperature. However, the surface temperature of the extruded sheet may be adjusted to a predetermined temperature at the position where the pressure laminating apparatus is attached.

  In the production method of the present invention, the softening point of the base film used for the transfer film is made lower than the surface temperature of the thermoplastic resin sheet at the time of transfer, and the surface temperature of the thermoplastic resin sheet at the time of transfer is set to (Tg− 10 ° C.) or more and (Tg + 70 ° C.) or less, the base film becomes soft at the time of transfer, and the transfer film has high flexibility. When pressure is applied with a relatively soft pressure-bonding roll, the transfer film enters the concave portion of the sheet surface, and the thin film can be transferred while following the uneven surface.

  The surface temperature of the thermoplastic resin sheet at the time of transfer is preferably in the range of (Tg) to (Tg + 50 ° C.), more preferably in the range of (Tg + 10 ° C.) to (Tg + 30 ° C.). When the surface temperature of the thermoplastic resin sheet at the time of transfer is less than (Tg-10 ° C), the adhesion of the thin film may be lowered. Conversely, if the surface temperature of the thermoplastic resin sheet at the time of transfer exceeds (Tg + 70 ° C.), the uneven shape on the sheet surface may not be maintained.

  In addition, since the softened base film is solidified again by cooling after transfer, it can be easily peeled from the thermoplastic resin sheet. Moreover, since the base film becomes softened at the time of transfer, it is necessary to appropriately select the thermoplastic resin constituting the thin film so as not to be compatible with the thermoplastic resin constituting the base film.

  The conditions for extrusion molding in the production method of the present invention, such as the discharge amount from the die, the distance between the die discharge port and the cooling roll, the rotational speed of the cooling roll, the rotational speed of the take-up roll, etc. What is necessary is just to set the substantially same conditions as the case of manufacturing, and it does not specifically limit. However, by adjusting the discharge amount from the die and the like, the surface temperature of the thermoplastic resin sheet at the position of the pressure roll is, when the glass transition temperature of the thermoplastic resin sheet is Tg, (Tg-10 ° C.) or more, It is necessary to be within the range of (Tg + 70 ° C.) or less. In general, the position where the surface temperature of the extruded sheet is near the glass transition temperature of the sheet moves to the downstream side in the flow direction of the extrusion and increases when the discharge amount from the die is increased. In addition, when the discharge amount from the die is reduced, the die moves to the upstream side in the flow direction of extrusion molding. In addition, you may install heating apparatuses, such as a heater, before a crimping | compression-bonding roll as needed.

  The structure of a typical sheet extruder used in the production method of the present invention is schematically shown in FIG. This sheet extruder 10 is a normal sheet extruder comprising an extrusion device (not shown), a die 11, a first cooling roll 12, a second cooling roll 13, a third cooling roll 14, a guide roll 15, and a take-up roll 16. In addition, a pressure laminating apparatus is attached between the third cooling roll 14 and the guide roll 15. Note that the pressure laminating apparatus is configured to supply the transfer film 17 in a state where tension is applied by the supply roll 18 and to press the transfer film 17 to the uneven surface 19 of the extruded sheet with the two pressure rolls 20. Yes.

  A process for producing a functional thermoplastic resin sheet using the sheet extruder 10 shown in FIG. 1 will be described below. First, the thermoplastic resin constituting the sheet and, if necessary, various additives are supplied to an extrusion device (not shown), sufficiently kneaded, and then extruded from the die 11 into a molten sheet. . The extruded sheet is introduced between the first cooling roll 12 and the second cooling roll 13 to advance on the peripheral surface of the second cooling roll 13, and then the second cooling roll 13 and the third cooling roll. 14 is introduced between the second cooling roller 14 and the third cooling roller 14 so that the transfer film 17 is overlapped with the supply roller 18 while being separated from the third cooling roller 14 at the position of the peeling line. In addition, after being crimped by the crimping roll 20, it is taken by the take-up roll 16 through the guide roll 15. At this time, in order to give an uneven shape to the surface 19 of the extruded sheet, for example, a decorating roll such as an embossing roll may be used as the second cooling roll 13. In addition, the 1st cooling roll 12 and the 3rd cooling roll 14 use a mirror surface roll with the smooth surface. Thus, the functional thermoplastic resin sheet 21 having at least one thin film transferred to the uneven surface is obtained.

  When the transfer film is pressure-bonded, the tension of the transfer film (the tension per unit length in the width direction of the roll supplying the transfer film) is 0.01 kg / cm or more and 0.1 kg / cm or less. Under pressure with a pressure roll that is heated to 30 ° C. or higher and 200 ° C. or lower, with a linear pressure of 1 kg / cm or higher and roll pressure (roll pressure per unit length in the width direction of the roll) of 1 kg / cm or lower. As a result, there is little distortion at the transfer joint surface, and transfer can be performed uniformly. If the tension of the transfer film is less than 0.01 kg / cm, the transfer film may be wrinkled. Conversely, when the tension of the transfer film exceeds 0.1 kg / cm, the thin film may crack due to the elongation of the transfer film. Further, if the temperature of the pressure-bonding roll is less than 30 ° C., the adhesion between the thermoplastic resin sheet and the transferred thin film may be low, or wrinkles may occur during pressure bonding. Conversely, when the temperature of the pressure-bonding roll exceeds 200 ° C., the surface of the thermoplastic resin sheet may be roughened, the undulation may be increased, or the base film may be torn off. Further, if the roll pressure of the thermocompression bonding roll is less than 1 kg / cm, air may be easily involved. Conversely, when the roll pressure of the pressure-bonding roll exceeds 10 kg / cm, optical distortion may occur in the obtained functional thermoplastic resin sheet.

  Note that it is preferable to use an expander roll type or spiral roll type roll as the transfer film supply roll because wrinkles can be prevented from occurring when the transfer film is pressure-bonded.

  The functional thermoplastic resin sheet thus obtained has a thin film transferred to the uneven surface, but the base film remains attached to the thin film. This base film may be peeled off during the manufacturing process, or when the functional thermoplastic resin sheet is used. The peel strength of the base film after transferring the thin film is preferably 0.02 N / cm or more and 1.0 N / cm or less. If the peel strength of the base film is within this range, the base film can be used as a thin film protective film. Here, the peel strength of the base film is a value measured at 180 ° direction and a tensile speed of 300 mm / min using a tensile tester.

  According to the manufacturing method of the present invention, the functional thermoplastic resin sheet having at least one thin film formed on the uneven surface can be efficiently manufactured by adopting the transfer method. It is advantageous.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, but may be appropriately modified within a range that can meet the purpose described above and below. It is also possible to implement, and they are all included in the technical scope of the present invention.

  First, evaluation and test methods used in Examples and Comparative Examples will be described.

<Thin film thickness>
With respect to the cross section of the transfer film in which a thin film is formed on the surface of the base film, arbitrary 10 points are sliced with a microtome to a thickness of 15 μm, and the cross section is observed with a microscope to measure the thickness of the thin film. The point average was taken as the thickness of the thin film.

<Thin film adhesion>
The adhesion of the thin film to the thermoplastic resin sheet is performed according to the former JIS K5400 (cross-cut tape test method). That is, 100 mm of 1 mm × 1 mm grids were engraved on the thin film transferred to the thermoplastic resin sheet using a cutter, and commercially available adhesive tapes (Cello Tape (registered trademark), Nichiban Co., Ltd.) After attaching, the adhesive tape is strongly peeled off by hand, and peeling of the thin film is determined according to the following criteria.
○: The peeled-off mesh is less than 10;
X: The peeled-off cell is 10 or more.

<Antistatic property>
The antistatic property is determined on the basis of the following criteria by measuring the surface resistance value in accordance with JIS K6911 after transferring the thin film to the uneven surface of the thermoplastic resin sheet.
○: The surface resistance value is less than 1 × 10 ¹² Ω;
X: The surface resistance value is 1 × 10 ¹² Ω or more.

<Light resistance>
For light resistance, after a thin film is transferred to the uneven surface of a thermoplastic resin sheet, ultraviolet rays with an intensity of 100 mW / cm ² are irradiated for 50 hours using an iSuper UV tester (SUV-W13 type, manufactured by Iwasaki Electric Co., Ltd.). From the yellowness before and after ultraviolet irradiation (YI) measured according to JIS Z8722, ΔYI is calculated by the formula: ΔYI = yellowness after ultraviolet irradiation (YI) −yellowness before ultraviolet irradiation (YI) Judgment is based on the following criteria.
○: ΔYI ≦ 5;
X: ΔYI> 5.

<Retentivity of uneven surface>
The retention of the uneven surface is visually determined by comparing the appearance of the sheet with the thin film transferred using the pressure-bonding roll with the appearance of the sheet without the thin film transferred by opening the pressure-bonding roll.
○: No significant change in appearance;
X: There is a great change in appearance.

<Comprehensive judgment>
Comprehensive judgment is “O” when all of “Adhesion”, “Antistatic”, “Light resistance” and “Uneven surface retention” are “O”, and “X” when at least one is “X”. To do.

  Next, preparation of a transfer film, extrusion molding of a thermoplastic resin sheet, and transfer of a thin film will be described.

<Preparation of transfer film>
Transfer film (1)
A high-density polyethylene film (HS-30, manufactured by Tamapoly Co., Ltd .; melting point 110 ° C., thickness 50 μm, width 300 mm) is used as a base film, and an acrylic resin (Hals Hybrid UV-G13; Nippon Shokubai Co., Ltd .; ethyl acetate solution) and quaternary ammonium salt type antistatic agent (Register PU-101, Daiichi Kogyo Seiyaku Co., Ltd.) are mixed at a solid content ratio of 1: 0.2. The applied solution was applied with a reverse roll coater and then dried at 80 ° C. for 5 minutes to form a thin film (thickness 3.5 μm) made of an ultraviolet-absorbing acrylic resin containing an antistatic agent on the base film. A formed transfer film (1) was obtained.

Transfer film (2)
A biaxially stretched polypropylene film (Treffan 2500S, manufactured by Toray Industries, Inc .; melting point 165 ° C., thickness 50 μm, width 300 mm) is used as a base film, and an acrylic resin (Hals Hybrid UV-G13) having ultraviolet absorptivity on one side. , Manufactured by Nippon Shokubai Co., Ltd .; ethyl acetate solution) and a quaternary ammonium salt type antistatic agent (Register PU-101, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) at a solid content ratio of 1: 0.2 The mixed solution was applied with a reverse roll coater and then dried at 80 ° C. for 5 minutes, so that a thin film (thickness 3.5 μm) made of an ultraviolet-absorbing acrylic resin containing an antistatic agent was formed on the base film. A layer-formed transfer film (2) was obtained.

Transfer film (3)
A biaxially stretched polyethylene terephthalate film (Lumirror S10, manufactured by Toray Industries, Inc .; melting point: 245 ° C., thickness: 38 μm, width: 300 mm) is used as a base film, and an acrylic resin (Hals Hybrid UV-G13) having ultraviolet absorption on one side , Manufactured by Nippon Shokubai Co., Ltd .; ethyl acetate solution) and a quaternary ammonium salt type antistatic agent (Register PU-101, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) at a solid content ratio of 1: 0.2 The mixed solution was applied with a reverse roll coater and then dried at 80 ° C. for 5 minutes, so that a thin film (thickness 3.5 μm) made of an ultraviolet-absorbing acrylic resin containing an antistatic agent was formed on the base film. A layer-formed transfer film (3) was obtained.

  The transfer films (1), (2), and (3) are in the form of a film roll by a processing apparatus that supplies the base film from the unwinding roll to the winding roll through the processing unit such as the coating unit and the drying unit. Got ready.

<Extrusion of thermoplastic resin sheet>
Acrylic resin (Delpet 70H, manufactured by Asahi Kasei Corporation; Tg: 103 ° C.), MS resin (Estyrene MS600, manufactured by Nippon Steel Chemical Co., Ltd .; Tg: 87 ° C.), PC resin (Iupilon E2000FN, Mitsubishi Engineering Plastics) Manufactured by Tg: 143 ° C.), COC resin (TOPAS 6013, manufactured by Ticona GmbH; Tg: 140 ° C.), PS resin (PSJ polystyrene SGP10, manufactured by PS Japan Co., Ltd .; Tg: 80 ° C.) as a thermoplastic resin, extruder (Screw diameter 50mmφ, L / D = 32, single axis), gear pump, die, cooling and mirror surface-decorative surface (embossed uneven surface)-unit consisting of three mirror surface cooling rolls, guide roll, take-up roll And a thermoplastic resin sheet having a width of 300 mm was produced by extrusion. An uneven shape was formed on one surface of the obtained thermoplastic resin sheet by the decorative surface of the second cooling roll.

  The resin temperature during extrusion molding is 260 ° C. for acrylic resin (Tg: 103 ° C.), 230 ° C. for MS resin (Tg: 87 ° C.), and 280 for PC resin (Tg: 143 ° C.). In the case of COC resin (Tg: 140 ° C), it was adjusted to 250 ° C, and in the case of PS resin (Tg: 80 ° C), it was adjusted to 170 ° C. Further, the distance between the die discharge port and the cooling roll and the rotation speed of the cooling roll and the take-up roll were adjusted so that the thickness of the sheet was 2 mm, and the sheet extrusion speed was 0.7 m / min.

Since the sheets obtained from the above-mentioned thermoplastic resins do not have a thin film, the surface resistance value exceeds 1 × 10 ¹⁶ Ω in all cases, and the light resistance is ΔYI of 10 except for the acrylic resin. That was all.

<Transfer of thin film>
Between the cooling roll and the guide roll, a static elimination air supply (SJ-R036, manufactured by Keyence Corporation) for the purpose of removing dust, and a far infrared panel heater for heating the extruded sheet Install and roll the transfer film in the form of a roll through the supply roll and pressure roll so that the thin film of the transfer film faces the uneven surface side of the extruded sheet while keeping the sheet surface temperature at a predetermined temperature. And continuously pressed and pressed onto the uneven surface of the extruded sheet. The sheet surface temperature was measured using a radiation thermometer (IR-TAF, manufactured by Chino Corporation).

  The pressure roll used was a metal roll with a shore hardness Hs60 silicone rubber lined with a thickness of 3 mm. The transfer film is pressure-bonded under such a tension that the tension of the transfer film (the tension per unit length in the width direction of the roll supplying the transfer film) is 0.03 kg / cm. , Roll pressure (roll pressure per unit length in the width direction of the roll) was performed while applying a pressure of 6 kg / cm.

Example 1
As explained above, after the acrylic resin is extruded into a sheet shape and the transfer surface (1) is pressure-bonded at a position adjusted so that the sheet surface temperature is 130 ° C., the base film is peeled off, A functional thermoplastic resin sheet was obtained. In addition, as for the degree of the uneven surface in the extruded acrylic resin sheet, the center line average roughness was 6.5 μm. Table 1 shows the evaluation results of the functional thermoplastic resin sheet.

<< Example 2 >>
As explained above, the MS resin is extruded into a sheet shape, and after the transfer film (1) is pressure-bonded at a position adjusted so that the sheet surface temperature is 120 ° C., the base film is peeled off, A functional thermoplastic resin sheet was obtained. In addition, as for the degree of the uneven surface in the extruded MS resin sheet, the center line average roughness was 4.8 μm. Table 1 shows the evaluation results of the functional thermoplastic resin sheet.

Example 3
As explained above, after extruding the PC resin into a sheet and adjusting the sheet surface temperature to 170 ° C., the transfer film (1) was pressure-bonded, and then the base film was peeled off. A functional thermoplastic resin sheet was obtained. The degree of the uneven surface of the extruded PC resin sheet was such that the center line average roughness was 5.2 μm. Table 1 shows the evaluation results of the functional thermoplastic resin sheet.

Example 4
As explained above, after extruding the COC resin into a sheet and adjusting the sheet surface temperature to be 170 ° C., the transfer film (1) is pressure-bonded, and then the base film is peeled off. A functional thermoplastic resin sheet was obtained. In addition, the degree of the uneven surface in the extruded COC resin sheet was such that the center line average roughness was 6.6 μm. Table 1 shows the evaluation results of the functional thermoplastic resin sheet.

Example 5
As explained above, the PS resin is extruded into a sheet shape, and after the transfer film (1) is pressure-bonded at a position adjusted so that the sheet surface temperature is 120 ° C., the base film is peeled off, A functional thermoplastic resin sheet was obtained. The degree of the uneven surface of the extruded PS resin sheet was such that the center line average roughness was 6.4 μm. Table 1 shows the evaluation results of the functional thermoplastic resin sheet.

Example 6
As explained above, after extruding the PC resin into a sheet shape and pressing the transfer film (2) at a position adjusted so that the sheet surface temperature is 200 ° C., the substrate film is peeled off, A functional thermoplastic resin sheet was obtained. In addition, as for the degree of the uneven surface in the extruded PC resin sheet, the center line average roughness was 3.8 μm. Table 1 shows the evaluation results of the functional thermoplastic resin sheet.

Example 7
As explained above, after extruding the COC resin into a sheet and adjusting the sheet surface temperature to be 170 ° C., after pressure-bonding the transfer film (2), the substrate film is peeled off, A functional thermoplastic resin sheet was obtained. In addition, as for the degree of the uneven surface in the extruded COC resin sheet, the center line average roughness was 5.5 μm. Table 1 shows the evaluation results of the functional thermoplastic resin sheet.

Example 8
As described above, silica spherical fine particles (Seahosta KE-P150, manufactured by Nippon Shokubai Co., Ltd .; average particle size 1.33-1.83 μm; these silica spherical fine particles function as a light diffusing agent) 0.5 mass After extruding a PC resin blended in a sheet shape and pressing the transfer film (1) at a position adjusted so that the sheet surface temperature is 200 ° C., the substrate film is peeled off, and the functional heat A plastic resin sheet (a light diffusion sheet imparted with surface functionality) was obtained. In addition, the degree of the uneven surface in the extruded PC resin sheet was such that the center line average roughness was 7.2 μm. Table 1 shows the evaluation results of the functional thermoplastic resin sheet.

Example 9
As described above, silica spherical fine particles (Seahosta KE-P150, manufactured by Nippon Shokubai Co., Ltd .; average particle size 1.33-1.83 μm; these silica spherical fine particles function as a light diffusing agent) 0.5 mass After extruding a PS resin blended in a sheet shape and pressing the transfer film (1) at a position adjusted so that the sheet surface temperature is 130 ° C., the substrate film is peeled off and the functional heat is removed. A plastic resin sheet (a light diffusion sheet imparted with surface functionality) was obtained. In addition, as for the degree of the uneven surface in the extruded PS resin sheet, the center line average roughness was 6.0 μm. Table 1 shows the evaluation results of the functional thermoplastic resin sheet.

≪Comparative example 1≫
As explained above, after the acrylic resin is extruded into a sheet shape and the transfer surface (2) is pressure-bonded at a position adjusted so that the sheet surface temperature is 130 ° C., the base film is peeled off, A functional thermoplastic resin sheet was obtained. As for the degree of the uneven surface in the extruded acrylic resin sheet, the center line average roughness was 5.4 μm. Table 1 shows the evaluation results of the functional thermoplastic resin sheet.

≪Comparative example 2≫
As described above, the MS resin is extruded into a sheet shape, and after the transfer film (2) is pressure-bonded at a position adjusted so that the sheet surface temperature is 120 ° C., the base film is peeled off, A functional thermoplastic resin sheet was obtained. In addition, as for the degree of the uneven surface in the extruded MS resin sheet, the center line average roughness was 6.5 μm. Table 1 shows the evaluation results of the functional thermoplastic resin sheet.

«Comparative Example 3»
As explained above, the MS resin is extruded into a sheet shape, and after the transfer film (2) is pressure-bonded at a position adjusted so that the sheet surface temperature is 180 ° C., the base film is peeled off, A functional thermoplastic resin sheet was obtained. In addition, as for the degree of the uneven surface in the extruded MS resin sheet, the center line average roughness was 7.1 μm. Table 1 shows the evaluation results of the functional thermoplastic resin sheet.

<< Comparative Example 4 >>
As explained above, after extruding the PC resin into a sheet and adjusting the sheet surface temperature to 180 ° C., the transfer film (3) was pressure-bonded, and then the base film was peeled off. A functional thermoplastic resin sheet was obtained. In addition, the degree of the uneven surface in the extruded PC resin sheet was such that the center line average roughness was 6.0 μm. Table 1 shows the evaluation results of the functional thermoplastic resin sheet.

<< Comparative Example 5 >>
As explained above, after the acrylic resin is extruded into a sheet shape and the transfer surface (1) is pressure-bonded at a position adjusted so that the sheet surface temperature is 80 ° C., the base film is peeled off, A functional thermoplastic resin sheet was obtained. The degree of the uneven surface in the extruded acrylic resin sheet was such that the center line average roughness was 3.8 μm. Table 1 shows the evaluation results of the functional thermoplastic resin sheet.

<< Comparative Example 6 >>
As explained above, after extruding the PC resin into a sheet and adjusting the sheet surface temperature to be 100 ° C., the transfer film (1) is pressure-bonded, and then the base film is peeled off. A functional thermoplastic resin sheet was obtained. The degree of the uneven surface of the extruded PC resin sheet was such that the center line average roughness was 5.5 μm. Table 1 shows the evaluation results of the functional thermoplastic resin sheet.

<< Comparative Example 7 >>
As explained above, PS resin is extruded into a sheet shape, and after the transfer film (3) is pressure-bonded at a position adjusted so that the sheet surface temperature is 180 ° C., the base film is peeled off, A functional thermoplastic resin sheet was obtained. The degree of the uneven surface in the extruded PS resin sheet was such that the center line average roughness was 6.3 μm. Table 1 shows the evaluation results of the functional thermoplastic resin sheet.

«Comparative Example 8»
As described above, the PC resin is extruded into a sheet shape, and after the transfer film (2) is pressure-bonded at a position adjusted so that the sheet surface temperature is 150 ° C., the base film is peeled off, A functional thermoplastic resin sheet was obtained. The degree of the uneven surface in the extruded PC resin sheet was such that the center line average roughness was 6.6 μm. Table 1 shows the evaluation results of the functional thermoplastic resin sheet.

  As is clear from Table 1, in Examples 1 to 9, the sheet surface temperature during transfer was within the range of (Tg-10 ° C.) or more and (Tg + 70 ° C.) or less when the glass transition temperature of the sheet was Tg. In addition, it satisfies the condition that the softening point (melting point) of the base film is lower than the sheet surface temperature at the time of transfer, so it has excellent thin film adhesion, antistatic properties, light resistance, and uneven surface retention. The overall judgment was “◯”.

  On the other hand, Comparative Examples 1 to 8 do not satisfy the above conditions, so at least one of antistatic properties, light resistance, and uneven surface retention was inferior, and the overall judgment was “x”. .

  Thus, if the thin film is transferred so as to satisfy the above-described conditions, even if the thermoplastic resin sheet has a concavo-convex surface, the adhesion of the thin film can be increased regardless of the type of thermoplastic resin constituting the sheet. It turns out that the functional thermoplastic resin sheet excellent in the retainability of the uneven | corrugated surface is obtained.

  Even if the thermoplastic resin sheet has an uneven surface, the present invention forms a thin film having functionality with high adhesion while following the uneven surface, and various functions ( For example, antistatic properties, light resistance, super water repellency, super hydrophilicity, anti-fogging properties, low reflectivity, anti-reflective properties, etc.) can be imparted, making a great contribution in a wide range of fields using thermoplastic resin sheets. It is what makes.

It is a schematic diagram which shows the structure of the typical sheet extruder used for the manufacturing method of this invention.

Explanation of symbols

10 Sheet Extruder 11 Die 12 First Cooling Roll (Mirror Surface Roll)
13 Second cooling roll (decorative roll)
14 Third cooling roll (mirror roll)
DESCRIPTION OF SYMBOLS 15 Guide roll 16 Take-off film 17 Transfer film 18 Supply roll 19 Uneven surface 20 Crimp roll 21 Functional thermoplastic resin sheet

Claims (9)

  A functional thermoplastic resin sheet having an uneven surface, wherein the thermoplastic resin sheet having an uneven surface has at least one layer of thin film formed on the uneven surface by a transfer method.   The functional thermoplastic resin sheet according to claim 1, wherein the thermoplastic resin constituting the sheet is made of an amorphous resin.   The functional thermoplastic resin sheet according to claim 1 or 2, wherein a resin constituting at least one layer of the thin film has ultraviolet absorptivity.   The functional thermoplastic resin sheet according to claim 1, wherein at least one layer of the thin film contains an antistatic agent.   The functional thermoplastic resin sheet according to claim 1, wherein at least one layer of the thin film contains a fluorescent brightening agent.   The functional thermoplastic resin sheet according to claim 1, wherein at least one layer of the thin film contains fine particles.   7. A light diffusing plate for a liquid crystal display device, wherein the functional thermoplastic resin sheet according to claim 1 is used for a backlight unit of a liquid crystal display device.   A method for producing the functional thermoplastic resin sheet according to claim 1, wherein the unevenness of the thermoplastic resin sheet having an uneven surface using a transfer film in which a thin film of at least one layer is formed on the surface of the base film. When the thin film is transferred to the surface, when the glass transition temperature of the thermoplastic resin sheet is Tg, the surface temperature of the thermoplastic resin sheet is within the range of (Tg−10 ° C.) or more and (Tg + 70 ° C.) or less. And a base film having a softening point lower than the surface temperature of the thermoplastic resin sheet.   A transfer film in which a thin film is formed on the surface of a base film, and as the base film, a low density polyethylene film, a high density polyethylene film, a linear low density polyethylene film, a biaxially stretched polypropylene film (OPP film) and A transfer film excellent in transferability to an uneven surface, wherein at least one film selected from unstretched polypropylene films (CPP films) is used.

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