JP2009126996A - Resin composition for light diffusion plate and light diffusion plate - Google Patents
Resin composition for light diffusion plate and light diffusion plate Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L25/00—Compositions of, homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring; Compositions of derivatives of such polymers
- C08L25/02—Homopolymers or copolymers of hydrocarbons
- C08L25/04—Homopolymers or copolymers of styrene
- C08L25/08—Copolymers of styrene
- C08L25/14—Copolymers of styrene with unsaturated esters
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
- C08K3/24—Acids; Salts thereof
- C08K3/26—Carbonates; Bicarbonates
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L33/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
- C08L33/04—Homopolymers or copolymers of esters
- C08L33/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, which oxygen atoms are present only as part of the carboxyl radical
- C08L33/10—Homopolymers or copolymers of methacrylic acid esters
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L33/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
- C08L33/04—Homopolymers or copolymers of esters
- C08L33/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, which oxygen atoms are present only as part of the carboxyl radical
- C08L33/10—Homopolymers or copolymers of methacrylic acid esters
- C08L33/12—Homopolymers or copolymers of methyl methacrylate
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L83/00—Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon only; Compositions of derivatives of such polymers
- C08L83/04—Polysiloxanes
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/02—Diffusing elements; Afocal elements
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
- G02F1/1336—Illuminating devices
- G02F1/133602—Direct backlight
- G02F1/133606—Direct backlight including a specially adapted diffusing, scattering or light controlling members
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
- C08K3/24—Acids; Salts thereof
- C08K3/26—Carbonates; Bicarbonates
- C08K2003/265—Calcium, strontium or barium carbonate
Abstract
Description
本発明は、高耐光、高耐熱、低吸水、高輝度、高光拡散である光拡散板及びそれに使用される樹脂組成物に関する。 The present invention relates to a light diffusing plate having high light resistance, high heat resistance, low water absorption, high luminance, and high light diffusion, and a resin composition used therefor.
樹脂を主材料とする光拡散透過性を有する光拡散板は、均一な輝度面が得られる。このため、光拡散板は、照明カバー、内部照明式看板、透過型ディスプレイなどの用途に、広く用いられている。近年では、液晶ディスプレイあるいは液晶テレビの直下型バックライト用の面光源体としての光拡散板の需要が伸びている。 A light diffusing plate having a light diffusibility and a resin as a main material can obtain a uniform luminance surface. For this reason, the light diffusing plate is widely used for applications such as a lighting cover, an internal lighting signboard, and a transmissive display. In recent years, the demand for a light diffusing plate as a surface light source body for a direct backlight of a liquid crystal display or a liquid crystal television is increasing.
光拡散板は、上記の機能を最適に発揮するために、光線をできる限り直進させることなく散乱させるとともに、できる限り散乱による光透過損失を抑えることが求められる。 The light diffusing plate is required to scatter the light ray without making it travel as straight as possible and to suppress the light transmission loss due to the scattering as much as possible in order to exhibit the above functions optimally.
このような要求特性を発現させる光拡散板を得るために、透明樹脂に炭酸カルシウム、硫酸バリウム、酸化チタン、酸化ケイ素、タルク、マイカ、水酸化アルミニウム、酸化マグネシウムなどの無機系粒子を添加する方法、スチレン系重合体粒子、アクリル系重合体粒子、シロキサン系重合体粒子などの部分的に架橋したポリマー微粒子を添加する方法、あるいはこれらを併用する方法により、添加物によって光を散乱させる手法が採用されてきた（例えば、特許文献１〜３参照）。 A method of adding inorganic particles such as calcium carbonate, barium sulfate, titanium oxide, silicon oxide, talc, mica, aluminum hydroxide, magnesium oxide to a transparent resin in order to obtain a light diffusing plate that exhibits such required characteristics Adopting a method that scatters light with additives by adding partially cross-linked polymer particles such as styrene polymer particles, acrylic polymer particles, siloxane polymer particles, or a combination of these. (For example, see Patent Documents 1 to 3).
光拡散板に用いられる透明樹脂として、アクリル樹脂、ポリカーボネート、そしてメタクリル酸メチル‐スチレン共重合体が挙げられるが、これらは、耐熱性、硬度、吸水性の面で満足する物性を有していない。また、特許文献４、５では、スチレン系単量体とメタクリル酸の共重合体に拡散剤を配合する手法が開示されており、耐熱性の向上に関しては改善されてきているが、スチレン系単量体が主成分であるため、耐光性に劣り、別途紫外線吸収層を設けるなどの手法が併用されている。また、特許文献６にはメタクリル酸メチル−スチレン系共重合体とメタクリル酸−スチレン系共重合体を含む高耐熱性樹脂組成物の開示がある。 Transparent resin used for the light diffusion plate includes acrylic resin, polycarbonate, and methyl methacrylate-styrene copolymer, but these do not have satisfactory physical properties in terms of heat resistance, hardness, and water absorption. . Patent Documents 4 and 5 disclose a method of blending a styrene monomer and methacrylic acid copolymer with a diffusing agent, and the improvement in heat resistance has been improved. Since the monomer is the main component, it is inferior in light resistance, and a technique such as providing a separate ultraviolet absorbing layer is also used. Patent Document 6 discloses a high heat resistant resin composition containing a methyl methacrylate-styrene copolymer and a methacrylic acid-styrene copolymer.
最近、液晶ディスプレイあるいは液晶テレビの部材特性の向上が図られている中、アクリル樹脂を用いた光拡散板は高吸水性を有するため、バックライト点灯時の反りが問題となっている。 Recently, improvement of member characteristics of a liquid crystal display or a liquid crystal television has been attempted. Since a light diffusing plate using acrylic resin has high water absorption, warpage at the time of lighting a backlight is a problem.
また、ディスプレイ使用中、バックライトが発熱するため、その直上にある光拡散板には耐熱性も求められる。しかし、従来のアクリル樹脂は、その特性を満足するものではない。 Further, since the backlight generates heat during use of the display, the light diffusion plate directly above it is also required to have heat resistance. However, conventional acrylic resins do not satisfy the characteristics.
さらには、耐熱スチレン樹脂は吸水性と耐熱性を改善するが、耐光性が劣り、長期のバックライトの照射で着色や機械物性の低下が発生し、ディスプレイとした時の色むらやワレが発生する。 In addition, heat-resistant styrene resin improves water absorption and heat resistance, but it is inferior in light resistance, and coloration and mechanical properties are deteriorated by long-term backlight irradiation, resulting in uneven color and cracking when used as a display. To do.
上記のように従来の光拡散板は、高耐光、高輝度、高光拡散、低吸水を必要とする光拡散板としての機能を十分に満足するものではない。 As described above, the conventional light diffusion plate does not sufficiently satisfy the function as a light diffusion plate requiring high light resistance, high luminance, high light diffusion, and low water absorption.
本発明は、上記の課題に鑑みてなされたものであり、高耐光、高耐熱、高低吸水、高輝度、高光拡散である光拡散板を提供することを目的とする。 The present invention has been made in view of the above problems, and an object of the present invention is to provide a light diffusing plate having high light resistance, high heat resistance, high and low water absorption, high luminance, and high light diffusion.
本発明者は、鋭意検討した結果、特定の組成を有するメタクリル酸メチル−スチレン系共重合体、メタクリル酸−スチレン系共重合体及び拡散剤からなる光拡散板用樹脂組成物を用いることにより成形された光拡散板が上記目的を達成できることを見出し、本発明を完成するに至った。 As a result of intensive studies, the present inventor has molded a light diffusion plate resin composition comprising a methyl methacrylate-styrene copolymer having a specific composition, a methacrylic acid-styrene copolymer, and a diffusing agent. The present inventors have found that the above-described light diffusing plate can achieve the above object, and have completed the present invention.
本発明に係る光拡散板用樹脂組成物は、メタクリル酸メチル−スチレン系共重合体２０〜８０重量部、メタクリル酸−スチレン系共重合体８０〜２０重量部を配合してなる樹脂組成物１００重量部に対して、光拡散剤０．１〜１０．０重量部配合してなることを特徴とする。 The resin composition for a light diffusing plate according to the present invention is a resin composition 100 comprising 20 to 80 parts by weight of a methyl methacrylate-styrene copolymer and 80 to 20 parts by weight of a methacrylic acid-styrene copolymer. The light diffusing agent is blended in an amount of 0.1 to 10.0 parts by weight with respect to parts by weight.
上記メタクリル酸メチル−スチレン系共重合体は、スチレン系単位の含有率が３０〜８０重量％であり、メタクリル酸−スチレン系共重合体のスチレン系単位の含有率が８０〜９８重量％であることがよく、上記光拡散剤は、部分的に架橋したシロキサン系重合体粒子、アクリル系重合体粒子又は炭酸カルシウムであり、粒径が１〜１０μｍであることがよい。 The methyl methacrylate-styrene copolymer has a styrene unit content of 30 to 80% by weight, and the methacrylic acid-styrene copolymer has a styrene unit content of 80 to 98% by weight. The light diffusing agent is preferably partially crosslinked siloxane polymer particles, acrylic polymer particles, or calcium carbonate, and preferably has a particle size of 1 to 10 μm.
また、本発明は上記光拡散板用樹脂組成物を溶融押出成形又は射出成形により、厚さ０．５〜３ｍｍの板状に成形された光拡散板に関する。 The present invention also relates to a light diffusing plate obtained by molding the above resin composition for a light diffusing plate into a plate having a thickness of 0.5 to 3 mm by melt extrusion molding or injection molding.
本発明の光拡散板用樹脂組成物に使用するメタクリル酸メチル−スチレン系共重合体及びメタクリル酸−スチレン系共重合体（以下、両者を総称して共重合体という）の製造法は、完全混合型反応器を用いた連続塊状重合法又は連続溶液重合法を利用することが組成や分子量の均一性と良好な外観を保持する上から望ましいが、バッチ式の塊状又は溶液重合でも可能である。重合時には開始剤を存在させることが好ましく、開始剤としては、通常のラジカル重合に使用する過酸化物及び／又はアゾ化合物が使用可能である。また、分子量を調節するためにアルキルメルカプタンのような連鎖移動剤を適量添加しても差し支えない。重合終了後は、常法により脱揮、ペレット化等の処理を行って本発明の光拡散板用樹脂組成物に使用する共重合体を得ることができる。 The method for producing methyl methacrylate-styrene copolymer and methacrylic acid-styrene copolymer (hereinafter collectively referred to as copolymer) used in the resin composition for light diffusion plate of the present invention is completely It is desirable to use a continuous bulk polymerization method or a continuous solution polymerization method using a mixed reactor from the viewpoint of maintaining uniformity in composition and molecular weight and good appearance, but batch type bulk polymerization or solution polymerization is also possible. . An initiator is preferably present at the time of polymerization, and as the initiator, a peroxide and / or an azo compound used for normal radical polymerization can be used. Further, an appropriate amount of a chain transfer agent such as an alkyl mercaptan may be added to adjust the molecular weight. After completion of the polymerization, a copolymer used for the resin composition for a light diffusing plate of the present invention can be obtained by performing treatments such as devolatilization and pelletization by a conventional method.
メタクリル酸メチル−スチレン系共重合体のスチレン系単位の含有率は３０〜８０重量％、好ましくは４５〜７５重量％であることがよい。メタクリル酸メチル−スチレン系共重合体のスチレン系単位単位の割合が３０重量％未満であると最終的な組成物が高吸湿性を有するため、反りが起こる材料となりやすく、８０重量％を超えると耐光性能が劣る傾向となりやすい。 The content of styrene units in the methyl methacrylate-styrene copolymer is 30 to 80% by weight, preferably 45 to 75% by weight. When the proportion of the styrene unit in the methyl methacrylate-styrene copolymer is less than 30% by weight, the final composition has a high hygroscopic property, so that the material tends to warp. It tends to be inferior in light resistance.
また、メタクリル酸−スチレン系共重合体のスチレン系単位の含有率は８０〜９８重量％、好ましくは８５〜９３重量％であることがよい。メタクリル酸−スチレン系共重合体のメタアクリル酸単位の割合が２重量％未満であると耐熱性が低すぎる傾向にあり、２０重量％を超えると重合時に架橋によるゲル発生量が過剰で表面にハシリのあるシートとなりやすい。 The content of styrene units in the methacrylic acid-styrene copolymer is 80 to 98% by weight, preferably 85 to 93% by weight. When the ratio of the methacrylic acid unit of the methacrylic acid-styrene copolymer is less than 2% by weight, the heat resistance tends to be too low, and when it exceeds 20% by weight, the amount of gel generated by crosslinking during polymerization is excessive and on the surface. It is easy to become a sheet with a file.
ここで、スチレン系単位は、上記共重合体を構成するスチレン系単位であり、共重合体を製造するために使用されるスチレン系モノマーに由来する単位をいう。
そして、これらの共重合体を配合して生じる光拡散板用樹脂組成物を構成する樹脂組成物（樹脂成分）に含まれるスチレン系単位の含有率が５０〜７７重量％、メタクリル酸メチル単位の含有率が１０〜４０重量％、メタクリル酸単位が３〜１０重量％を含むものが好ましい。光拡散板用樹脂組成物とそれを構成する樹脂組成物（樹脂成分）を区別する場合、前者を光拡散板用樹脂組成物といい、後者を樹脂組成物という。
Here, the styrenic unit is a styrenic unit constituting the copolymer, and refers to a unit derived from a styrenic monomer used for producing the copolymer.
And the content rate of the styrene-type unit contained in the resin composition (resin component) which comprises the resin composition for light diffusing plates produced by mix | blending these copolymers is 50 to 77 weight%, methyl methacrylate unit What contains 10 to 40 weight% and a methacrylic acid unit contains 3 to 10 weight% is preferable. When distinguishing the resin composition for light diffusing plates and the resin composition (resin component) which comprises it, the former is called the resin composition for light diffusing plates, and the latter is called a resin composition.
このメタクリル酸メチル−スチレン系共重合体及びメタクリル酸−スチレン系共重合体中のスチレン系単位としては、スチレン単位の他、置換スチレン単位類があり、これらの単位を１種以上有することもできる。有利には、スチレン単位である。 As the styrene unit in the methyl methacrylate-styrene copolymer and the methacrylic acid-styrene copolymer, there are substituted styrene units in addition to the styrene unit, and one or more of these units may be included. . Advantageously, styrene units.
このようなスチレン系単位を与えるモノマーとしては、スチレンの他、クロロスチレン、ブロモスチレンのようなハロゲン化スチレン類、ビニルトルエン、α−メチルスチレンのようなアルキルスチレン類などの置換スチレン類がある。 Monomers that give such styrenic units include styrene, halogenated styrenes such as chlorostyrene and bromostyrene, and substituted styrenes such as alkyltoluenes such as vinyltoluene and α-methylstyrene.
更に、メタクリル酸メチル−スチレン系共重合体においては、メタクリル酸メチル単位以外の１種以上の（メタ）アクリル酸エステル類単位を少量有することもできる。（メタ）アクリル酸エステル類単位を与えるモノマーとしては、メタクリル酸エチル、メタクリル酸ブチル、メタクリル酸シクロヘキシル、メタクリル酸オクタデシル、メタクリル酸フェニル、メタクリル酸ベンジル、メタクリル酸オクタデシル、メタクリル酸２−エチルヘキシルなどのようなメタクリル酸エステル類、アクリル酸メチル、アクリル酸エチル、アクリル酸ブチル、アクリル酸シクロヘキシル、アクリル酸フェニル、アクリル酸ベンジル、アクリル酸２−エチルヘキシルなどのようなアクリル酸エステル類などが挙げられる。 Further, the methyl methacrylate-styrene copolymer may have a small amount of one or more (meth) acrylic acid ester units other than the methyl methacrylate unit. Monomers that give (meth) acrylic acid ester units include ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, octadecyl methacrylate, phenyl methacrylate, benzyl methacrylate, octadecyl methacrylate, 2-ethylhexyl methacrylate, and the like. Methacrylic acid esters, methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, and the like.
本発明において使用されるメタクリル酸メチル−スチレン系共重合体及びメタクリル酸−スチレン系共重合体共重合体は、公知の方法により重合して製造することができる。このメタクリル酸メチル−スチレン系共重合体及びメタクリル酸−スチレン系共重合体共重合体の重量平均分子量は、ともに１００００〜４０００００であることが好ましい。１０００００未満であると流動性が高くなり、シートの厚みコントロールが困難となる。また、４０００００以上となると流動性が低く、成形温度を上げなければならず、着色することがある。 The methyl methacrylate-styrene copolymer and the methacrylic acid-styrene copolymer copolymer used in the present invention can be produced by polymerization by a known method. The weight average molecular weights of the methyl methacrylate-styrene copolymer and the methacrylic acid-styrene copolymer are both preferably 10,000 to 400,000. If it is less than 100,000, the fluidity becomes high and it becomes difficult to control the thickness of the sheet. Moreover, when it becomes 400000 or more, fluidity | liquidity is low, and the molding temperature must be raised and it may color.
また、上記２種類の共重合体のメルトフローレートは、それぞれ０．５〜３．０g/10minの範囲とすることがよい。好ましくは０．５〜２．５g/10minである。メルトフローレート３．０g/10minより高くなると厚みムラのあるシートとなりやすく、メルトフローレート０．５g/10min未満になると流動性が低すぎるため、成形困難となる。 The melt flow rate of the two types of copolymers is preferably in the range of 0.5 to 3.0 g / 10 min. Preferably it is 0.5-2.5g / 10min. When the melt flow rate is higher than 3.0 g / 10 min, a sheet with uneven thickness tends to be formed, and when the melt flow rate is less than 0.5 g / 10 min, the fluidity is too low, so that molding becomes difficult.
また、この光拡散板用樹脂組成物のビカット軟化温度（ＶＳＴ）は、１０３℃以上、好ましくは１０５〜１３０℃であることがよい。ビカット軟化温度１０３℃未満であるとバックライトの発熱に対する耐熱性が低いため、基材の変形等が発生しやすくなる。 Moreover, the Vicat softening temperature (VST) of this resin composition for light diffusing plates is 103 degreeC or more, Preferably it is 105-130 degreeC. If the Vicat softening temperature is less than 103 ° C., the heat resistance of the backlight against heat generation is low, so that the substrate is likely to be deformed.
また、上記光拡散板用樹脂組成物は、吸水率０．３０％以下、好ましくは０．２５％以下であることがよい。吸水率０．３０％を超えると吸水による反りの問題が発生しやすくなる。 The light diffusion plate resin composition has a water absorption of 0.30% or less, preferably 0.25% or less. If the water absorption exceeds 0.30%, the problem of warpage due to water absorption tends to occur.
本発明に係る光拡散板用樹脂組成物は、メタクリル酸メチル−スチレン系共重合体２０〜８０重量部、メタクリル酸−スチレン系共重合体８０〜２０重量部を配合してなる樹脂組成物１００部（重量部）に対して光拡散剤を０．１〜１０．０部、好ましくは０．２〜５．０部存在させるように配合して得られる。配合量が０．１部未満であると光源の隠蔽性に欠けるため、バックライト光源のイメージに起因する輝度ムラの目立つ光拡散板となる。１０．０部を超えると透過光量が不十分なため、明るさの不足した光拡散板となる。 The resin composition for a light diffusing plate according to the present invention is a resin composition 100 comprising 20 to 80 parts by weight of a methyl methacrylate-styrene copolymer and 80 to 20 parts by weight of a methacrylic acid-styrene copolymer. It is obtained by blending the light diffusing agent in an amount of 0.1 to 10.0 parts, preferably 0.2 to 5.0 parts relative to parts (parts by weight). If the blending amount is less than 0.1 part, the light source is not concealed, so that a light diffusion plate with noticeable luminance unevenness due to the image of the backlight light source is obtained. If the amount exceeds 10.0 parts, the amount of transmitted light is insufficient, resulting in a light diffusing plate with insufficient brightness.
光拡散剤としては、公知の微粒子を使用することができるが、好ましくは粒径１〜１０μｍの部分的に架橋したシロキサン系重合体粒子、アクリル系重合体粒子又は炭酸カルシウムである。これらの拡散剤は１種のみを使用しても、数種を使用してもよい。また、その他の拡散剤として、硫酸バリウム、酸化チタン、酸化ケイ素、タルク、マイカ、水酸化アルミニウム、酸化マグネシウムなどの無機系粒子やスチレン系重合体粒子を併用することもできるが、拡散剤の５０重量％未満にとどめることがよい。 As the light diffusing agent, known fine particles can be used, and preferably, partially crosslinked siloxane polymer particles, acrylic polymer particles or calcium carbonate having a particle diameter of 1 to 10 μm. These diffusing agents may be used alone or in combination. In addition, as other diffusing agents, inorganic particles such as barium sulfate, titanium oxide, silicon oxide, talc, mica, aluminum hydroxide, magnesium oxide, and styrene polymer particles can be used in combination. It is better to keep it below the weight percent.
共重合体と拡散剤の混合は公知の方法で均一混合物となるように行うことができる。このようにして得られる光拡散板用樹脂組成物は、押出成形又は射出成形して厚さ０．５〜３mmの板状に成形することが有利である。厚さが０．５mm未満であると、バックライト用拡散板としての強度が確保できない。また、厚さが３mmを越えると、拡散板重量が大きくなるため、大型化、薄型化に対応できない。これを、そのまま又は所定サイズに切断又は表面処理等をして、本発明に係る光拡散板とする。しかし、その製造方法は、本発明の目的を満足できれば、特に限定されるものではない。 The copolymer and the diffusing agent can be mixed by a known method so as to form a uniform mixture. The resin composition for a light diffusing plate thus obtained is advantageously formed into a plate having a thickness of 0.5 to 3 mm by extrusion molding or injection molding. If the thickness is less than 0.5 mm, the strength as a backlight diffusion plate cannot be secured. On the other hand, if the thickness exceeds 3 mm, the weight of the diffusion plate increases, so that it cannot cope with an increase in size and thickness. This is cut or surface-treated as it is or with a predetermined size to obtain a light diffusing plate according to the present invention. However, the production method is not particularly limited as long as the object of the present invention can be satisfied.
本発明の光拡散板は、上記光拡散板用樹脂組成物から構成されていれば、単一の層で構成されてもよいし、二層以上の多層で構成されてもよい。 As long as the light diffusing plate of the present invention is composed of the above resin composition for light diffusing plate, it may be composed of a single layer or may be composed of two or more layers.
本発明の光拡散板は、メタクリル酸メチル−スチレン系樹脂とメタクリル酸−スチレン系樹脂と拡散剤を使用することで、高耐光、高耐熱、高低吸水、高輝度、高光拡散等の物性を実現するものであるが、この目的を著しく阻害しない範囲であれば、必要に応じて、帯電防止剤、酸化防止剤、難燃剤、光安定剤、紫外線吸収剤、蛍光増白剤などの種々の添加剤を使用することもできる。 The light diffusion plate of the present invention realizes physical properties such as high light resistance, high heat resistance, high and low water absorption, high luminance, and high light diffusion by using methyl methacrylate-styrene resin, methacrylic acid-styrene resin and a diffusing agent. If necessary, various additions such as an antistatic agent, an antioxidant, a flame retardant, a light stabilizer, an ultraviolet absorber, and a fluorescent brightening agent Agents can also be used.
本発明の光拡散板は、光拡散性と光透過性のバランスが要求される用途、主として液晶ディスプレイあるいは液晶テレビの直下型バックライト用拡散板として用いられ、特に、大型、薄型化に伴い、高耐光、耐熱性、高硬度を要求される用途に好適である。そして、本発明に係る光拡散板用樹脂組成物から得られる光拡散板は、高耐熱、低吸水であり、耐光性に優れる。 The light diffusing plate of the present invention is used as a diffusing plate for a direct backlight of a liquid crystal display or a liquid crystal television, mainly used in applications where a balance between light diffusibility and light transmittance is required. Suitable for applications requiring high light resistance, heat resistance, and high hardness. And the light diffusing plate obtained from the resin composition for light diffusing plates which concerns on this invention is high heat resistance, low water absorption, and is excellent in light resistance.
以下、実施例により本発明を具体的に説明するが、本発明はこれら実施例に限定されるものではない。 EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to these Examples.
光拡散板用樹脂組成物に使用される共重合体の物性の測定は、以下の方法により行なった。
（１）分子量
ゲルパーミエーションクロマトグラフィーを使用しポリスチレン換算の重量平均分子量を測定した。
（２）共重合体中の各単位組成
メタクリル酸メチル−スチレン系共重合体の各単位組成は熱分解型ガスクロマトグラフィーのモノマーの面積比より各モノマー単位組成を算出し、メタクリル酸−スチレン系共重合体の各単位組成は共重合体のメタクリル酸単位を電位差自動滴定装置で滴定し算出した。
（３）メルトフローレート（ＭＦＲ）
ＪＩＳ Ｋ‐７２１０に準拠して２００℃、5ｋｇ荷重で行なった。
（４）ビカット軟化温度（ＶＳＴ）
ＪＩＳ Ｋ‐７２０６に準拠して行なった。
（５）吸水率
ＪＩＳ Ｋ−７２０９に準拠して測定した。
The physical properties of the copolymer used in the resin composition for a light diffusing plate were measured by the following method.
(1) Molecular weight Gel permeation chromatography was used to measure the weight average molecular weight in terms of polystyrene.
(2) Each unit composition in the copolymer The unit composition of the methyl methacrylate-styrene copolymer is calculated from the monomer area ratio of the pyrolysis gas chromatography monomer, and the methacrylic acid-styrene system. Each unit composition of the copolymer was calculated by titrating the methacrylic acid unit of the copolymer with an automatic potentiometric titrator.
(3) Melt flow rate (MFR)
According to JIS K-7210, it was performed at 200 ° C. and 5 kg load.
(4) Vicat softening temperature (VST)
This was performed in accordance with JIS K-7206.
(5) Water absorption Measured according to JIS K-7209.
光拡散板の物性評価は、以下の方法により行なった。
（１）全光線透過率
ＪＩＳ Ｋ７１０５のＢ法に準拠して行なった。
（２）光拡散性
２ｃｍ間隔に冷陰極管４本を並べ、１０ｍｍ上に光拡散板サンプルを平行に固定し、目視により、光源である冷陰極管が透けていないものを○、透けているものを×で示した。
（３）輝度ムラ
２ｃｍ間隔に冷陰極管４本を並べ、１０ｍｍ上に光拡散板サンプルを平行に固定し、目視により、画面上で輝度が均一であるものは○、輝度ムラがあるものは×で、若干のムラがあるが使用に問題ないレベルのものを△で示した。
（４）耐光性
メタルハライドランプを光源とした促進耐光性試験機を使用しフィルター：KF-1(透過波長領域；295〜780nm) 、運転モード：連続照射、UV照度：75mW/cm2、BP温度：80℃
、槽内湿度：50％RH 、スプレー：無い 、試験時間：24時間、サンプル厚みは2ｍｍシートを使用した。耐光試験後のサンプルを分光型測色計を使用し透過光のΔEで評価した。
The physical properties of the light diffusing plate were evaluated by the following methods.
(1) Total light transmittance It carried out based on B method of JISK7105.
(2) Light diffusivity Four cold cathode tubes are arranged at intervals of 2 cm, a light diffusing plate sample is fixed in parallel on 10 mm, and the cold cathode tube which is a light source is visually transparent when it is transparent. The thing was shown by x.
(3) Luminance unevenness 4 cold-cathode tubes are arranged at intervals of 2 cm, a light diffusion plate sample is fixed in parallel on 10 mm, and visually, the brightness is uniform on the screen, ○, the brightness unevenness is X indicates a slight unevenness but no problem in use.
(4) Light resistance Using an accelerated light resistance tester with a metal halide lamp as the light source, filter: KF-1 (transmission wavelength range; 295 to 780 nm), operation mode: continuous irradiation, UV illuminance: 75 mW / cm 2 , BP temperature : 80 ℃
, Humidity in the tank: 50% RH, Spray: None, Test time: 24 hours, Sample thickness was 2 mm. The sample after the light resistance test was evaluated by ΔE of transmitted light using a spectroscopic colorimeter.
また、実施例及び比較例中で使用する略号は次の意味を有する。
ＭＭＡ：メタクリル酸メチル
ＭＡＡ：メタクリル酸
Ｓｔ：スチレン
開始剤：パーカドックス１２‐ＥＢ２０
Moreover, the symbol used in an Example and a comparative example has the following meaning.
MMA: Methyl methacrylate MAA: Methacrylic acid St: Styrene Initiator: Parkardox 12-EB20
参考例１〜9
原料モノマー及び重合開始剤を表１のポリマー組成になるように仕込み、反応温度１２０℃、５時間滞留条件下で、一槽型完全混合反応器と脱揮槽を連結した設備を用いて連続塊状重合、脱揮、ペレット化し、目的とする透明な共重合体を得た。該樹脂を７５ｔ成形機（三菱重工製）により、樹脂温度２４０℃にて射出成形を行い、縦５０×横７５ｍｍ×厚さ４ｍｍの吸水率測定用プレート、縦１０×横１０ｍｍ×厚さ４ｍｍのＶＳＴ測定用試験片を得た。得られた共重合体の組成を表１に記載する。表１において、共重合体組成は、ＭＡＡ単位／ＭＭＡ単位／Ｓｔ単位である。分子量及び各種の物性について測定した結果も表１に示す。
Reference Examples 1-9
The raw material monomer and the polymerization initiator were charged so as to have the polymer composition shown in Table 1, and the reaction temperature was 120 ° C. and the residence condition was 5 hours. Polymerization, devolatilization, and pelletization were performed to obtain a desired transparent copolymer. The resin was injection-molded at a resin temperature of 240 ° C. with a 75 t molding machine (Mitsubishi Heavy Industries), and a water absorption measurement plate having a length of 50 × width of 75 mm × thickness of 4 mm, length of 10 × width of 10 mm × thickness of 4 mm A test piece for VST measurement was obtained. The composition of the obtained copolymer is shown in Table 1. In Table 1, the copolymer composition is MAA unit / MMA unit / St unit. Table 1 also shows the results measured for the molecular weight and various physical properties.
実施例１〜４及び比較例１〜２
参考例にて作製した共重合体、及び表２に示す拡散剤を二軸押出機にて混練、ペレット化した光拡散板用樹脂組成物とした。この光拡散板用樹脂組成物を、樹脂温度２２０℃にて押出成形して厚さ２ｍｍの光拡散板を作製した。得られた光拡散板の全光線透過率、光拡散性、輝度ムラについて表２に記載する。ここで使用したシロキサン系重合体粒子は平均粒径２μｍ、アクリル系重合体粒子は平均粒径１０μｍ、炭酸カルシウムは平均粒径１．８μｍであり、表２においてはシロキサン系重合体粒子をシロキサン系と、アクリル系重合体粒子をアクリル系と、炭酸カルシウムを炭カルと略記する。
Examples 1-4 and Comparative Examples 1-2
A resin composition for a light diffusing plate was prepared by kneading and pelletizing the copolymer prepared in Reference Example and the diffusing agent shown in Table 2 with a twin screw extruder. This resin composition for a light diffusing plate was extruded at a resin temperature of 220 ° C. to produce a light diffusing plate having a thickness of 2 mm. Table 2 shows the total light transmittance, light diffusibility, and luminance unevenness of the obtained light diffusing plate. The siloxane polymer particles used here have an average particle diameter of 2 μm, the acrylic polymer particles have an average particle diameter of 10 μm, and calcium carbonate has an average particle diameter of 1.8 μm. In Table 2, the siloxane polymer particles are siloxane-based. Acrylic polymer particles are abbreviated as acrylic, and calcium carbonate is abbreviated as carbon cal.
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| JP2007305692A JP2009126996A (en) | 2007-11-27 | 2007-11-27 | Resin composition for light diffusion plate and light diffusion plate |
| TW097144618A TW200936677A (en) | 2007-11-27 | 2008-11-19 | Light dispersion plate and resin combination thereof |
| KR1020080117847A KR20090054912A (en) | 2007-11-27 | 2008-11-26 | Resin composition for light diffusing plate and light diffusing plate |
| CNA2008101786641A CN101446651A (en) | 2007-11-27 | 2008-11-27 | Light dispersion plate and resin combination thereof |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009126997A (en) * | 2007-11-27 | 2009-06-11 | Nippon Steel Chem Co Ltd | Resin composition for light diffusion plate and light diffusion plate |
| JP2013082800A (en) * | 2011-10-07 | 2013-05-09 | Denki Kagaku Kogyo Kk | Styrenic resin composition for light guide, and light guide |
| CN104987643A (en) * | 2015-07-13 | 2015-10-21 | 上海金泛斯标识有限公司 | Light diffusion plate for illuminated advertising board and preparation method of light diffusion plate |
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| JP7286269B2 (en) * | 2018-03-23 | 2023-06-05 | 恵和株式会社 | backlight unit |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002020564A (en) * | 2000-07-03 | 2002-01-23 | Asahi Kasei Corp | Oriented sheet of styrenic resin composition |
| JP2006022255A (en) * | 2004-07-09 | 2006-01-26 | Denki Kagaku Kogyo Kk | Styrenic resin composition and its molded product |
| WO2006057355A1 (en) * | 2004-11-26 | 2006-06-01 | Denki Kagaku Kogyo Kabushiki Kaisha | Multilayer sheet and light diffusion sheet |
| JP2007153959A (en) * | 2005-12-01 | 2007-06-21 | Nippon Steel Chem Co Ltd | Resin composition for light-diffusing plate and light-diffusing plate |
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- 2007-11-27 JP JP2007305692A patent/JP2009126996A/en active Pending
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2008
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002020564A (en) * | 2000-07-03 | 2002-01-23 | Asahi Kasei Corp | Oriented sheet of styrenic resin composition |
| JP2006022255A (en) * | 2004-07-09 | 2006-01-26 | Denki Kagaku Kogyo Kk | Styrenic resin composition and its molded product |
| WO2006057355A1 (en) * | 2004-11-26 | 2006-06-01 | Denki Kagaku Kogyo Kabushiki Kaisha | Multilayer sheet and light diffusion sheet |
| JP2007153959A (en) * | 2005-12-01 | 2007-06-21 | Nippon Steel Chem Co Ltd | Resin composition for light-diffusing plate and light-diffusing plate |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009126997A (en) * | 2007-11-27 | 2009-06-11 | Nippon Steel Chem Co Ltd | Resin composition for light diffusion plate and light diffusion plate |
| JP2013082800A (en) * | 2011-10-07 | 2013-05-09 | Denki Kagaku Kogyo Kk | Styrenic resin composition for light guide, and light guide |
| CN104987643A (en) * | 2015-07-13 | 2015-10-21 | 上海金泛斯标识有限公司 | Light diffusion plate for illuminated advertising board and preparation method of light diffusion plate |
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| CN101446651A (en) | 2009-06-03 |
| TW200936677A (en) | 2009-09-01 |
| KR20090054912A (en) | 2009-06-01 |
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