JP2009084521A - Acrylic resin film and light diffusion plate - Google Patents

Abstract

Provided are an acrylic resin film having a long-lasting antistatic performance and excellent light resistance and a good appearance, and a light diffusing plate in which the acrylic resin film is laminated on at least one surface of the light diffusing plate. To do.
An acrylic resin (A), a polymer antistatic agent (B), and an ultraviolet absorber (C) are contained, and the content of the ultraviolet absorber (C) is 100 parts by mass of the acrylic resin (A). A light diffusion plate in which the acrylic resin film is laminated on the surface of an acrylic resin film and a light diffusion plate that are 0.01 to 1.3 parts by mass.
[Selection figure] None

Description

  The present invention relates to an acrylic resin film and a light diffusion plate having an acrylic resin film laminated on the surface.

  Acrylic resins are used for vehicular lamps, display devices, equipment nameplates, and the like because of their excellent optical properties. For example, it has been proposed to use an acrylic resin as a protective layer of a polycarbonate resin light diffusion plate used in a direct type backlight unit (Patent Documents 1 and 2). However, since the acrylic resin is an electrical insulator, the acrylic resin is charged due to various factors when manufacturing the light diffusing plate or assembling the backlight unit. As a result, there is a problem that dust adheres to the surface of the light diffusing plate, thereby causing defects in display characteristics such as a decrease in luminance of the display surface and image quality spots.

  Under such circumstances, there is an increasing demand for a material having a sustained antistatic performance while maintaining the excellent transparency of the acrylic resin.

  In response to this demand, there has been proposed a technique using a polymer type antistatic agent having a feature that the antistatic performance does not depend on humidity and the antistatic performance is maintained for a long time. For example, Patent Document 3 proposes a molded body obtained by injection molding or extrusion molding a thermoplastic resin composition containing a polyether ester amide compound as a polymer antistatic agent. Further, Patent Document 4 proposes a polyether olefin copolymer which is a block polymer having a polyolefin block and a hydrophilic polymer block as a polymer antistatic agent, and a resin composition containing the copolymer. A molded product obtained by injection molding is disclosed.

However, when these polymer type antistatic agents are blended to impart long-term antistatic performance to the acrylic resin film, and further, an ultraviolet absorber is blended to improve light resistance, the surface of the resulting acrylic resin film In addition, the ultraviolet absorber bleeds out and the appearance deteriorates.
JP 2005-148186 A JP 2005-234521 A JP-A-11-199667 JP 2001-278985 A

  The present invention provides an acrylic resin film having a long-lasting antistatic performance and excellent light resistance, and a good appearance, and a light diffusion plate in which the acrylic resin film is laminated on the surface of the light diffusion plate. With the goal.

  The present invention contains an acrylic resin (A), a polymer antistatic agent (B) and an ultraviolet absorber (C), and the content of the ultraviolet absorber (C) is 100 parts by mass of the acrylic resin (A). An acrylic resin film having a content of 0.01 to 1.3 parts by mass is defined as the first invention.

  Moreover, this invention makes the light-diffusion board by which said acrylic resin film was laminated | stacked on at least one surface of the light-diffusion board as 2nd invention.

  According to the present invention, it is possible to obtain an acrylic resin film that has a long-lasting antistatic performance and excellent light resistance and suppresses bleeding out of an ultraviolet absorber. Also, by laminating this acrylic resin film on the surface of the light diffusing plate, it prevents dust and the like from adhering to the light diffusing plate for a long time, and also suppresses yellowing of the light diffusing plate due to light irradiation, and A light diffusing plate having a good appearance can be obtained. As a result, it is possible to provide a light diffusing plate with good luminance.

<Acrylic resin (A)>
As the acrylic resin (A) used for the acrylic resin film of the present invention, in the presence of a rubber polymer containing an alkyl acrylate ester as a structural unit, a monomer having a methacrylic acid alkyl ester as a main component or Examples include a polymer (I) obtained by polymerizing a monomer mixture, or a resin composition in which the polymer (I) is further blended with a polymer (II) whose main constituent unit is an alkyl methacrylate. . For example, a polymer or a resin composition described in JP-B-59-36646, JP-B-62-19309, JP-A-63-77963, and JP-A-2006-146029 is used. Can do.

  In the polymer (I), the rubber polymer mainly composed of alkyl acrylate is 50 to 99.9% by mass of alkyl acrylate, and other monomers having a copolymerizable double bond 0 to 49. It is obtained from 9% by mass, 0-10% by mass of the polyfunctional monomer and 0.1-10% by mass of the grafting agent.

  The alkyl acrylate ester may have a linear or branched alkyl group. Specific examples thereof include methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, and n-octyl acrylate. These can be used individually or in mixture of 2 or more types. Of these, n-butyl acrylate is preferred.

  Other monomers having a copolymerizable double bond include methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate alkyl esters such as lower alkoxy acrylate, cyanoethyl acrylate, acrylamide, Acrylic monomers such as acrylic acid and methacrylic acid, styrene, alkyl-substituted styrene, acrylonitrile, methacrylonitrile, unsaturated dicarboxylic anhydrides such as maleic anhydride and itaconic anhydride, N-phenylmaleimide, N-cyclohexylmaleimide Etc. These can be used individually or in mixture of 2 or more types. Of these, methyl methacrylate is preferred.

  A polyfunctional monomer is a monomer having two or more copolymerizable double bonds in one molecule. As specific compounds, alkylene glycol dimethacrylates such as ethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, 1,4-butylene glycol dimethacrylate, and propylene glycol dimethacrylate are preferable. Polyvinylbenzene such as divinylbenzene and trivinylbenzene can also be used. In addition, triallyl cyanurate, triallyl isocyanurate and the like are also effective. These can be used individually or in mixture of 2 or more types. Of these, 1,3-butylene glycol dimethacrylate is preferred.

  A graft crossing agent is a monomer having two or more different copolymerizable double bonds in one molecule. Specific examples thereof include allyl, methallyl or crotyl ester of copolymerizable α, β-unsaturated carboxylic acid or dicarboxylic acid. Particularly preferred are allyl esters of acrylic acid, methacrylic acid, maleic acid or fumaric acid. Of these, allyl methacrylate is preferable because of its excellent effect. In addition, triallyl cyanurate, triallyl isocyanurate and the like are also effective. These can be used individually or in mixture of 2 or more types. Graft-crossing agents are chemically bonded, primarily with the conjugated unsaturated bonds of their esters reacting much faster than allyl, methallyl or crotyl groups.

  A rubber polymer having an alkyl acrylate as a main component is obtained by polymerizing a monomer or monomer mixture containing a monomer containing an alkyl methacrylate and then a monomer having an alkyl acrylate as a main component. Alternatively, a monomer mixture may be polymerized.

Other chain transfer agents can be used. The chain transfer agent can be selected from those used for normal radical polymerization. Specific examples include alkyl mercaptans having 2 to 20 carbon atoms, mercapto acids, thiophenol, carbon tetrachloride, and the like. Acrylic acid alkyl esters and heavy monomers obtained from other monomers having a copolymerizable double bond. It is preferable that the glass transition temperature calculated | required by the formula of united FOX is less than 25 degreeC.

  In the presence of the rubber polymer, it contains 80 to 100% by weight of methacrylic acid alkyl ester, 0 to 20% by weight of acrylic acid alkyl ester and 0 to 20% by weight of other monomer having a copolymerizable double bond. A polymer (I) is obtained by polymerizing a monomer or a monomer mixture mainly composed of alkyl methacrylate. Other chain transfer agents can be used. Examples of the methacrylic acid alkyl ester, acrylic acid alkyl ester, and other monomers having a copolymerizable double bond include those described above. As the methacrylic acid alkyl ester, methyl methacrylate is particularly preferred.

  Monomers or monomer mixtures based on alkyl methacrylates are alkyl methacrylates, alkyl methacrylates and other monomers having a copolymerizable double bond in the presence of a rubber polymer. It may be polymerized after at least one monomer or monomer mixture selected from is polymerized.

  Examples of the method for producing the polymer (I) include a sequential multistage polymerization method. In addition, an emulsion polymerization method is generally used as a polymerization method in each stage. For example, an emulsion suspension polymerization method in which the emulsion polymerization is converted to a suspension polymerization system at the next polymerization after the emulsion polymerization is also possible.

  An anionic surfactant, a cationic surfactant, and a nonionic surfactant can be used as the surfactant used in preparing an emulsion during emulsion polymerization, and an anionic surfactant is preferable.

  Anionic surfactants include, for example, rosin soap; carboxylates such as potassium oleate, sodium stearate, sodium myristate, sodium N-lauroyl sarcosinate, dipotassium alkenyl succinate; sulfate esters such as sodium lauryl sulfate Salts: Sodium dioctylsulfosuccinate, sodium dodecylbenzenesulfonate, sodium alkyldiphenyl ether disulfonate, etc .; phosphate salts such as sodium polyoxyethylene alkylphenyl ether phosphate; sodium polyoxyethylene alkyl ether phosphate And phosphoric acid ester salts.

  Preferred examples of the surfactant include NC-718 (trade name) manufactured by Sanyo Chemical Industries, Ltd., Phosphanol LS-529, Phosphanol RS-610NA, manufactured by Toho Chemical Industry Co., Ltd. Phanol RS-620NA, Phosphanol RS-630NA, Phosphanol RS-640NA, Phosphanol RS-650NA and Phosphanol RS-660NA (each trade name), Latemul P-0404 manufactured by Kao Corporation LATEMUL P-0405, LATEMUL P-0406 and LATEMUL P-0407 (each trade name) are listed.

  A well-known thing can be used as a polymerization initiator. Examples of the polymerization initiator include peroxides, azo initiators, and redox initiators obtained by combining these with an oxidizing agent / reducing agent. Among these, redox initiators are preferable, and sulfoxylate initiators in which ferrous sulfate, ethylenediaminetetraacetic acid disodium salt, longalite, and hydroperoxide are combined are particularly preferable.

  As a method for adding a polymerization initiator, it can be added to either one or both of an aqueous phase and a monomer phase.

  Although superposition | polymerization temperature can be arbitrarily set with the kind and quantity of the polymerization initiator to be used, 40-120 degreeC is preferable and 60-95 degreeC is more preferable.

  In the present invention, various polymerization aids may be used when the polymer (I) is obtained by emulsion polymerization.

  As described above, the polymer (I) obtained by emulsion polymerization is recovered from the latex state.

  Examples of a method for recovering the polymer from the polymer latex include a salting out or acid precipitation coagulation method or a spray drying or freeze drying method, and the powder is recovered in a powder form.

  The polymer (II) contains a methacrylic acid alkyl ester as a main structural unit. Other monomers having copolymerizable double bonds other than methacrylic acid alkyl esters can be used. Other chain transfer agents can be used. Examples of these monomers include those described above. The polymer (II) can be produced by a known polymerization method such as suspension polymerization, emulsion polymerization, solution polymerization or bulk polymerization.

  The usage-amount of polymer (I) and polymer (II) is 20-100 mass% and 80-0 mass%, respectively.

<Polymer type antistatic agent (B)>
In the present invention, the polymer type antistatic agent (B) is used as the antistatic agent in that the antistatic effect of the acrylic resin film is excellent.

  Examples of the polymer antistatic agent (B) include polyethylene oxide, block polymers of polyolefin and hydrophilic polymer, polymers containing polyether moieties such as polyether ester amide and polyether amide imide, and quaternary ammonium. Examples thereof include polymers containing a quaternary ammonium base such as a base-containing acrylate copolymer.

  Among these, in order to obtain an optically transparent acrylic resin film, a block polymer or polyether ester of a polyolefin and a hydrophilic polymer having a small refractive index difference from the acrylic resin as the polymer antistatic agent (B) It is preferable to use an amide.

  Examples of the block polymer of polyolefin and hydrophilic polymer include, for example, a reaction product of a polyolefin having a functional group and a hydrophilic polymer having a functional group capable of reacting with the functional group. And a block having a structure in which the block is repeatedly bonded alternately through an ester bond, an amide bond, an ether bond, a urethane bond, an imide bond, or the like.

  Examples of the polyolefin include polyolefins having functional groups such as a carboxyl group, a hydroxyl group, and an amino group at both ends of the polymer.

  In addition, the above hydrophilic polymers include polyether diols such as polyoxyalkylene having a hydroxyl group as a functional group, polyether ester amide obtained from a polyamide having a carboxyl group at both ends and polyether diol, polyamide imide and poly Examples thereof include polyetheramide imide obtained from ether diol, polyether ester obtained from polyester and polyether diol, and polyether amide obtained from polyamide and polyether diamine.

  The ratio of the hydrophilic polymer in the block polymer of polyolefin and hydrophilic polymer is preferably 20 to 90% by mass.

  Specific examples of the block polymer of polyolefin and hydrophilic polymer include Pelestat 230 (trade name, refractive index 1.50) and Pelestat 300 (trade name, refractive index 1.49) manufactured by Sanyo Chemical Industries, Ltd. .

  Examples of the polyether ester amide include polyether ester amide obtained by polycondensation of polyamide and polyether diol.

  As the above polyamide, an aminocarboxylic acid or lactam having 6 or more carbon atoms, at least one polyamide-forming monomer selected from nylon salts having 6 or more carbon atoms obtained from diamine and dicarboxylic acid, and a cyclic structure in the molecule. It is derived from a dicarboxylic acid having 4 to 20 carbon atoms.

  Examples of the polyether diol include at least one ethylene oxide adduct selected from polyoxyalkylene glycols and bisphenol compounds.

  Specific examples of the polyether ester amide include TPAE-H151 (trade name, refractive index 1.49) manufactured by Fuji Chemical Industry Co., Ltd.

  The refractive index difference between the block polymer of polyolefin and hydrophilic polymer or the polyether ester amide and the acrylic resin (A) is preferably 0.01 or less, and preferably 0.005 or less in order to improve the transparency of the acrylic resin film. More preferred.

  When a block polymer or polyether ester amide of polyolefin and hydrophilic polymer is used as the polymer antistatic agent (B), the content of the block polymer or polyether ester amide of polyolefin and hydrophilic polymer is acrylic resin ( A) 30 mass parts or less are preferable with respect to 100 mass parts. When the content is 30 parts by mass or less, a balance between antistatic performance and colorability after film formation, water absorption, transparency, impact strength, appearance, and moldability tends to be obtained. The content of block polymer or polyether ester amide of polyolefin and hydrophilic polymer is more preferably 20 parts by mass or less, and further preferably 15 parts by mass or less.

  In the present invention, a surfactant-type antistatic agent can be used in combination with the polymer-type antistatic agent (B) as necessary.

  Examples of the surfactant type antistatic agent include alkyl sulfonates and glycerin fatty acid esters.

<Ultraviolet absorber (C)>
Examples of the ultraviolet absorber (C) include triazine compounds, benzotriazole compounds, benzophenone compounds, cyanoacrylate compounds, salicylate compounds, and benzoate compounds. Among these, triazine compounds that are excellent in ultraviolet cut-off properties are preferable.

Examples of the triazine compound include 2,4,6-triaryltriazine represented by the following general formula (1).

In the formula, R ¹ , R ² , R ³ and R ⁴ are the same or different and are at least one selected from hydrogen, hydroxy group, alkyl group, alkoxy group, sulfoxyl group, carboxy group, halogen, haloalkyl group and allylamino group. is there. R ⁵ is hydrogen, an alkyl group having 1 to 18 carbon atoms, or an aliphatic or cycloaliphatic containing oxygen. Examples of the aliphatic or cycloaliphatic containing oxygen are preferably groups represented by the following general formulas (2), (3), (4), (5), (6), and (7).

  The molecular weight of the ultraviolet absorber (C) is preferably 300 or more, more preferably 400 or more.

  Specific examples of the ultraviolet absorber (C) include Tinuvin 1577 (trade name) manufactured by Ciba Specialty Chemicals Co., Ltd. and Adeka Stub LA46 (trade name) manufactured by Adeka Corporation.

  Content of a ultraviolet absorber (C) is 0.01-1.3 mass part with respect to 100 mass parts of acrylic resins (A). When the ultraviolet absorber (C) is used in combination with an antistatic agent, light resistance is obtained when the content of the ultraviolet absorber (C) is 0.01 parts by mass or more, and bleeding problems occur when the content is 1.3 parts by mass or less. Does not occur. As for content of a ultraviolet absorber (C), 0.5-1.0 mass part is preferable.

<Acrylic resin film>
As thickness of the acrylic resin film of this invention, 10-500 micrometers is preferable at the point of film physical property and workability. When the thickness of the acrylic resin film is 10 to 500 μm, there is a tendency to have an appropriate rigidity, the laminating property, the secondary workability and the like are easy, and the film forming property is stable and the film production tends to be easy. As for the thickness of an acrylic resin film, 15-200 micrometers is more preferable, and 30-200 micrometers is still more preferable.

  The haze of the acrylic resin film of the present invention is preferably 10% or less when measured according to JIS K7136. When the acrylic resin film has a haze of 10% or less, the light from the light source is efficiently transmitted when the acrylic resin film is laminated on the light diffusing plate. Therefore, the liquid crystal display device using this has good light emission quality. become.

  The acrylic resin film of the present invention contains an acrylic resin (A), a polymer type antistatic agent (B), and an ultraviolet absorber (C), and if necessary, a stabilizer, a lubricant, a processing aid, and a plasticizer. Common compounding agents such as impact resistance aids, fillers, mold release agents and the like can be blended. Moreover, when laminating the acrylic resin film of the present invention on a light diffusion plate, it is preferable to add a hindered amine light stabilizer (HALS) in order to further improve the light resistance.

  As a method for adding the above-mentioned additive, when forming the resin composition into a film, a method of supplying the molding machine together with the acrylic resin (A) and a mixture to which the additive is added are kneaded and mixed in various kneaders. There is a method of forming a resin composition. Examples of the kneader used in the latter method include ordinary single screw extruders, twin screw extruders, Banbury mixers, roll kneaders, and the like.

  Examples of the method for forming the resin composition into a film include melt extrusion methods such as a known melt casting method, T-die method, and inflation method. Among these, the T-die method is preferable from the viewpoint of economy.

<Light diffusion plate>
The acrylic resin film of the present invention can be used by being laminated on at least one surface selected from the surface on the light source side and the surface on the liquid crystal side of the light diffusion plate for backlight.

  Examples of the material of the light diffusion plate used in the present invention include methacrylic resin, polycarbonate resin, methyl methacrylate-styrene resin (MS resin), polystyrene resin, polyvinyl chloride resin, polyester resin, and cyclic polyolefin resin. Of these, methacrylic resins and polycarbonate resins having high light transmittance are preferred.

  As the light diffusing plate, a material obtained by dispersing a light diffusing agent in the above resin can be used. As the light diffusing agent, those which are transparent, have light resistance, heat resistance and moisture resistance and have high light diffusibility are preferable.

  Examples of the light diffusing agent include acrylic resins, styrene resins, polyester resins, melamine resins, silicone resins, epoxy resins, urethane resins, polyethylene, nylon resins, norbornene resins, cyclohexane resins, and vinyl chloride resins. Organic substances; and inorganic substances such as crystalline silica, glass, lithium fluoride, calcium carbonate, and barium sulfate.

  The light diffusing plate is preferably transparent, has a high light transmittance, a low birefringence, and can be easily laminated with an acrylic resin film, and more preferably a light diffusing plate for a direct backlight.

  When the light diffusion plate laminated with the acrylic resin film of the present invention is used as a light diffusion plate of a direct type backlight, the acrylic resin film of the present invention is laminated and used on both the light source side and the liquid crystal side of the light diffusion plate. Can do. The light diffusing plate on which the acrylic resin film is laminated can suppress yellowing of the light diffusing plate by a light source and can suppress a decrease in luminance due to adhesion of dust or the like. Therefore, a liquid crystal display device using this direct type backlight Can maintain the color tone and light emission quality in a color liquid crystal display for a long time.

  Examples of the method of laminating the acrylic resin film of the present invention on the light diffusion plate include coextrusion methods such as a coextrusion T-die method and a coextrusion lamination method. The acrylic resin film can be laminated on the light diffusion plate by a known method such as a method of laminating by a film lamination method such as a dry lamination method or a heat lamination method, or a laminating method by a coating method of a solution of a resin composition. Among these, a coextrusion method and a film lamination method are preferable, and a film lamination method is more preferable, which can easily obtain a light diffusing plate having a simple and continuous and stable quality.

  Hereinafter, the present invention will be described by way of examples. In the examples and comparative examples, “part” represents “part by mass”. Abbreviations indicate the following compounds, respectively.

MMA: methyl methacrylate MA: methyl acrylate BA: butyl acrylate St: styrene AMA: allyl methacrylate 1,3BD: 1,3-butylene glycol dimethacrylate tBH: t-butyl hydroperoxide CHP: cumene hydroperoxide SFS: sodium formaldehyde Sulfoxylate EDTA: Ethylenediaminetetraacetic acid disodium salt nOM: n-octyl mercaptan RS-610NA: sodium mono-n-dodecyloxytetraoxyethylene phosphate (trade name; Phosphanol RS-610NA, manufactured by Toho Chemical Co., Ltd.) )
In Examples and Comparative Examples, evaluation of the prepared polymer, acrylic resin film, and light diffusion plate laminated with acrylic resin film were evaluated by the following methods, respectively.

(1) Mass average particle diameter of polymer The polymer latex obtained by emulsion polymerization was measured by a dynamic light scattering method using a light scattering photometer DLS-700 (trade name) manufactured by Otsuka Electronics Co., Ltd.

(2) Gel content of polymer About 0.5 g (mass before extraction) of the weighed polymer was extracted for 4 hours under reflux in an acetone solvent, and the extracted solution was separated by centrifugation. Subsequently, the mass after drying (mass after extraction) of the obtained solid content was measured, and the gel content was determined by the following formula.

Gel content rate (%) = {(mass before extraction−mass after extraction) / mass before extraction} × 100
(3) Haze of acrylic resin film Evaluated according to JIS K7136.

(4) Presence / absence of bleed-out on acrylic resin film surface The acrylic resin film was left in an environment of 23 ° C. and 50% RH for 180 days, and then the acrylic resin film surface was visually observed to confirm the presence / absence of bleed-out.

○: No bleed-out ×: With bleed-out (5) Antistatic performance of acrylic resin film In accordance with JIS K6911, the acrylic resin film is left in a state of 23 ° C. and 50% RH for 24 hours and then applied in the same atmosphere. The surface resistivity was measured using a super insulation meter (SM-10E type (trade name) manufactured by Toa Denpa Kogyo Co., Ltd.) under the condition of a voltage of 500 V, and the antistatic performance was evaluated.

(6) Dust adhesion of light diffusion plate A light diffusion plate laminated with an acrylic resin film was hung indoors at 25 ° C. and 50% RH for two months, and the degree of dust adhesion was visually evaluated according to the following criteria.

○: Dust adhesion is hardly seen.

X: Dust adheres and the light diffusion plate appears cloudy.

(7) Antistatic performance of light diffusing plate The light diffusing plate on which the acrylic resin film was laminated was allowed to stand for 500 hours in an environment of 60 ° C. and 95% RH and in an environment of 80 ° C. and 0% RH. The surface resistivity of the surface was measured, and the antistatic performance was evaluated according to the following criteria.

A: 1 × 10 ¹³ Ω / cm ² or less.

○: More than 1 × 10 ¹³ Ω / cm ² and 1 × 10 ¹⁵ / cm ² or less.

×: Over 1 × 10 ¹⁵ Ω / cm ²

(8) Light resistance of light diffusing plate The degree of discoloration of the light diffusing plate and the degree of deterioration of antistatic performance after the surface of the light diffusing plate laminated with the acrylic resin film is exposed under the conditions shown below. Evaluation based on the criteria.

(Cold cathode tube actual exposure conditions)
Cold cathode tube: φ2.6 lamp, lamp current: 8 mA, 3 parallel, ambient temperature and humidity: 23 ° C, 50% RH
Distance between lamp and sample surface: 1.4mm (design value)
Sample surface temperature: approx. 50 ° C
Exposure period: 6 months (degree of discoloration)
○: No discoloration ×: Discoloration (Decrease in antistatic performance)
○: The surface resistivity of the surface of the acrylic resin film is hardly lowered.

    X: The surface resistivity of the surface of the acrylic resin film was significantly reduced.

[Example 1]
<Production of polymer (H-1)>
After charging 8.5 parts of ion-exchanged water into a container equipped with a stirrer, the monomer mixture (a) shown below was added and stirred and mixed. Next, 1.1 parts of RS-610NA was charged into the container while stirring the mixture, and then stirring was continued for 20 minutes to obtain an emulsion (N-1). The average particle size of the dispersed phase in the emulsion (N-1) was 10 μm.

  Next, 186.5 parts of ion-exchanged water was added to the emulsion (N-1), and the temperature was raised to 70 ° C. in a nitrogen atmosphere. Thereafter, a polymerization assistant mixture prepared by adding the following polymerization assistant (b) to 5 parts of ion-exchanged water was added all at once.

  Furthermore, the emulsion (N-1) was added dropwise to the polymerization vessel over 8 minutes while stirring in a nitrogen atmosphere, and then the reaction was continued for 15 minutes to complete the polymerization of the polymer (A-1).

  Subsequently, the monomer mixture (c) shown below was dropped into the polymerization vessel over 90 minutes under a nitrogen atmosphere, and then the reaction was continued for 60 minutes to obtain a polymer (B-1).

  Subsequently, the monomer mixture (d) shown below was dropped into the polymerization vessel over 45 minutes under a nitrogen atmosphere, and then the reaction was continued for 60 minutes to form a polymer (D-1).

  Subsequently, the monomer mixture (e) shown below was dropped into the polymerization vessel over 140 minutes under a nitrogen atmosphere, and then the reaction was continued for 60 minutes to form a polymer (C-1) to form a four-stage polymerization. A polymer latex of polymer (H-1) was obtained. The mass average particle diameter of the polymer in the polymer latex was 0.12 μm.

Monomer mixture (a)
MMA 0.3 part BA 4.5 part 1,3BD 0.2 part AMA 0.05 part CHP 0.025 part
Polymerization aid (b)
SFS 0.2 part Ferrous sulfate 0.0001 part EDTA 0.0003 part
Monomer mixture (c)
MMA 1.5 parts BA 22.5 parts 1,3BD 1.0 part AMA 0.25 parts CHP 0.016 parts
Monomer mixture (d)
MMA 6 parts BA 4 parts AMA 0.075 parts CHP 0.0125 parts
Monomer mixture (e)
MMA 55.2 parts BA 4.8 parts nOM 0.204 parts tBH 0.08 parts The polymer latex of the obtained polymer (H-1) was attached to a filter medium with a mesh made of SUS (average opening 62 μm). Filtration was performed using a vibration type filtration apparatus. Thereafter, the filtrate was put into a 3% calcium acetate aqueous solution for salting out, and the salted-out product was washed with water and dried to obtain a powdery polymer (H-1).

  The gel content of the polymer (H-1) was 60%. Further, when the polymer (H-1) was dispersed in acetone, the number of particles having a diameter of 55 μm or more present in the dispersion was 18 per 100 g of the polymer.

  Next, 100 parts of polymer (H-1), 10 parts of TPAE-H151 (trade name) manufactured by Fuji Kasei Kogyo Co., Ltd. as an antistatic agent, and Tinuvin 1577 manufactured by Ciba Specialty Chemicals Co., Ltd. as an ultraviolet absorber. 0.7 parts of (trade name) and 0.1 part of Irganox 1076 (trade name) manufactured by Ciba Specialty Chemicals Co., Ltd. as an antioxidant were blended and then mixed using a Henschel mixer. Next, the obtained mixture was supplied to a degassing extruder (TEM-35B (trade name) manufactured by Toshiba Machine Co., Ltd.) heated to 230 ° C. and kneaded to obtain pellets.

  The pellets were dried overnight at 80 ° C., and the resulting dried pellets were supplied to a 40 mmφ non-vent screw extruder (L / D = 26) equipped with a 300 mm wide T-die to obtain an acrylic resin film having a thickness of 50 μm. Produced. The conditions at this time were a cylinder temperature of 200 ° C. to 240 ° C., a T die temperature of 250 ° C., and a cooling roll temperature of 70 ° C.

  In addition, acrylic polymer fine particles (Paraloid EXL-5136 (trade name) manufactured by Rohm and Haas Company, mass average particle diameter: 7 μm) 3 in a polycarbonate resin having a viscosity average molecular weight of 24,300 obtained from bisphenol A and phosgene. .5 parts added and mixed using a vented T-die extruder and melt extruded under conditions of an extruder temperature of 250 to 300 ° C., a die temperature of 260 to 300 ° C., and a vacuum degree of the vent part of 26.6 kPa, and a thickness of 2 mm In addition, a light diffusion plate made of polycarbonate resin having a width of 1,000 mm was obtained.

  The acrylic resin film was heat-laminated to the light diffusion plate at 140 ° C. to obtain a light diffusion plate on which the acrylic resin film was laminated.

The total light transmittance of the acrylic resin film, haze, presence / absence of bleed-out and antistatic performance, and dust adhesion, antistatic performance and light resistance of the light diffusion plate were evaluated. The evaluation results are shown in Table 1.

[Example 2]
Ten parts of Pelestat 230 (trade name) manufactured by Sanyo Chemical Industries, Ltd. were used as an antistatic agent. Other than that was carried out similarly to Example 1, and obtained the 50-micrometer-thick acrylic resin film and the light diffusing plate which laminated | stacked this acrylic resin film. Table 1 shows the results of the same evaluation as in Example 1.

[Example 3]
Ten parts of Pelestat 300 (trade name) manufactured by Sanyo Chemical Industries, Ltd. were used as an antistatic agent. Other than that was carried out similarly to Example 1, and obtained the 50-micrometer-thick acrylic resin film and the light diffusing plate which laminated | stacked this acrylic resin film. Table 1 shows the results of the same evaluation as in Example 1.

[Comparative Example 1]
An acrylic resin film having a thickness of 50 μm and a light diffusing plate laminated with this acrylic resin film were obtained in the same manner as in Example 1 except that the ultraviolet absorber was not used. Table 1 shows the results of the same evaluation as in Example 1.

[Comparative Example 2]
An acrylic resin film having a thickness of 50 μm and a light diffusing plate laminated with this acrylic resin film were obtained in the same manner as in Example 1 except that the antistatic agent was not used. Table 1 shows the results of the same evaluation as in Example 1.

[Comparative Example 3]
10 parts of Pelestat 300 (trade name) manufactured by Sanyo Chemical Industries, Ltd. were used as the antistatic agent, and 1.4 parts of Tinuvin 1577 (trade name) manufactured by Ciba Specialty Chemicals Co., Ltd. were used as the ultraviolet absorber. Other than that was carried out similarly to Example 1, and obtained the light-diffusion plate which laminated | stacked the acrylic resin film of 50 micrometers in thickness, and an acrylic resin film. Table 1 shows the results of the same evaluation as in Example 1.

  From the examples and comparative examples, the following became clear.

  In Examples 1 to 3, the obtained acrylic resin films had good transparency and antistatic performance, and the ultraviolet ray absorbent did not bleed out on the film surface and the appearance was good. Moreover, the light diffusing plate laminated with this acrylic resin film had good antistatic performance and light resistance.

  On the other hand, in Comparative Example 1, since the ultraviolet absorber was not contained, the light diffusion plate on which the acrylic resin film was laminated exhibited a decrease in light resistance. Moreover, in Comparative Example 2, since the antistatic agent was not contained, the light diffusion plate on which the acrylic resin film was laminated had high dust adhesion and low light emission quality. Furthermore, since the ultraviolet absorber was excessively contained in Comparative Example 3, the ultraviolet absorber was bleeding out on the surface of the acrylic resin film.

Claims (3)

  It contains an acrylic resin (A), a polymer antistatic agent (B) and an ultraviolet absorber (C), and the content of the ultraviolet absorber (C) is 0.01 with respect to 100 parts by mass of the acrylic resin (A). The acrylic resin film which is -1.3 mass part.   The acrylic resin film according to claim 1, wherein the acrylic resin film has a haze of 10% or less.   A light diffusion plate in which the acrylic resin film according to claim 1 or 2 is laminated on at least one surface of the light diffusion plate.