JP2007192861A - Light diffusing plate - Google Patents

Light diffusing plate Download PDF

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JP2007192861A
JP2007192861A JP2006008396A JP2006008396A JP2007192861A JP 2007192861 A JP2007192861 A JP 2007192861A JP 2006008396 A JP2006008396 A JP 2006008396A JP 2006008396 A JP2006008396 A JP 2006008396A JP 2007192861 A JP2007192861 A JP 2007192861A
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light
resin
aromatic vinyl
weight
resin composition
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Tomonori Kinoshita
智典 木下
Masayuki Nozawa
正行 野沢
Yasuji Shichijo
保治 七條
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Nippon Steel Chemical and Materials Co Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a light diffusing plate which has high brightness and high light diffusion and which is light in weight. <P>SOLUTION: The light diffusion plate is obtained by molding a resin composition produced by blending one kind of aromatic vinyl resin (A), which is obtained by homopolymerization of an aromatic vinyl monomer and which has weight average molecular weight of 250,000 to 400,000, with one or more kinds of aromatic vinyl compound-unsaturated carboxylic acid ester compound copolymerized thermoplastic resins (B) which has weight average molecular weight of 250,000 to 400,000. The resin composition has phase separation structure, content of the unsaturated carboxylic acid ester compound (B) is 5 to 80 wt.%, whole light transmittance of the light diffusing plate is 40 to 70%, parallel light transmittance is 6.5% or less and thickness of the plate is 0.5 to 3mm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

本発明は、照明カバーやディスプレイなどの用途に広く用いられる光拡散板に関する。   The present invention relates to a light diffusing plate that is widely used in applications such as lighting covers and displays.

樹脂を主材料として製造され、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。特に近年では、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 manufactured using resin as a main material and having light diffusibility can obtain a uniform luminance surface. For this reason, the light diffusing plate is widely used for applications such as an illumination cover, an internal illumination signboard, and a transmissive display. In particular, 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、上記の機能を好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 suitably exhibit the above function.

このような要求特性を発現させるために、光拡散板は、従来、透明性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)。   In order to express such required characteristics, the light diffusing plate has conventionally used inorganic particles such as calcium carbonate, barium sulfate, titanium oxide, silicon oxide, talc, mica, aluminum hydroxide, and magnesium oxide in a transparent resin. Light is scattered by the additive by the method of adding, the method of adding partially crosslinked polymer fine particles such as styrene polymer particles, acrylic polymer particles, siloxane polymer particles or the like, or the method of using these in combination. A technique has been adopted (see, for example, Patent Documents 1 to 3).

また、均一な輝度になるような拡散性、優れた透明性を持ち、明るい拡散光の得られる光拡散シートを作製するために、メタアクリル酸エステル系樹脂、非晶質環状オレフィン系樹脂を用い、海島構造をとらせた検討もされてきた(例えば、特許文献4、5参照)。   In addition, methacrylic ester resins and amorphous cyclic olefin resins are used to produce light diffusing sheets with uniform diffusibility, excellent transparency, and bright diffused light. In addition, studies have been made with a sea-island structure (see, for example, Patent Documents 4 and 5).

一方、不飽和カルボン酸エステル化合物共重合熱可塑性樹脂の混合に関しては、相分離構造を応用した真珠光沢樹脂の検討がなされている(特許文献6参照)。   On the other hand, regarding the mixing of unsaturated carboxylic acid ester compound copolymerized thermoplastic resins, studies have been made on nacreous resins applying a phase separation structure (see Patent Document 6).

特許3195543公報Japanese Patent No. 3195543 特許3195544公報Japanese Patent No. 3195544 特許2512544公報Japanese Patent No. 2512544 特開2005‐181825公報JP 2005-181825 A 特開平10‐111402公報JP-A-10-111402 特開昭58‐118841公報Japanese Patent Laid-Open No. 58-118841

ところが、液晶ディスプレイあるいは液晶テレビの大画面化が進み、これに伴ってバックライト用拡散板も大型化しているため、比重の大きな無機系粒子を使用する場合には重量の問題が、高価な架橋ポリマー微粒子を使用する場合にはコストの問題がある。   However, since the screen of liquid crystal displays or liquid crystal televisions has been enlarged and the diffusion plate for the backlight has been enlarged accordingly, when using inorganic particles having a large specific gravity, the problem of weight is an expensive crosslinking. When polymer fine particles are used, there is a problem of cost.

また、これまで検討されてきた海島構造では、界面のサイズが大きすぎて、光拡散し難く、バックライトの遮蔽性が低く、拡散性も高くないものであった。   Further, in the sea-island structure that has been studied so far, the size of the interface is too large, light diffusion is difficult, the backlight shielding property is low, and the diffusion property is not high.

更に、従来の拡散シート等は軽くて強度に優れ、高輝度、高光拡散である大型光拡散板としての機能を満足するものではなかった。   Further, the conventional diffusion sheet and the like are light and excellent in strength, and do not satisfy the function as a large light diffusion plate having high luminance and high light diffusion.

本発明は、上記の課題に鑑みてなされたものであり、高輝度、高光拡散、軽量、高強度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 luminance, high light diffusion, light weight, and high strength.

本発明者は、鋭意検討した結果、特定の要件を満たした屈折率の異なる樹脂間の界面を光拡散源として用いることにより、上記目的に適う光拡散板が得られることを見出し、本発明を完成するに至った。   As a result of intensive studies, the present inventor has found that a light diffusing plate suitable for the above purpose can be obtained by using an interface between resins having different refractive indexes satisfying specific requirements as a light diffusing source. It came to be completed.

すなわち本発明は、単独重合して得られる芳香族ビニル系樹脂(A)1種類と、芳香族ビニル化合物と不飽和カルボン酸エステル化合物を共重合して得られる共重合熱可塑性樹脂(B)1種類以上を混合してなる樹脂組成物を成形して得られる光拡散板であって、熱可塑性共重合樹脂(B)の不飽和カルボン酸エステル化合物単位の含有量が5〜80重量%であり、樹脂組成物が相分離構造を有し、光拡散板の全光線透過率が40〜70%、平行光線透過率が6.5%以下、板の厚さが0.5〜3mmであることを特徴とする光拡散板である。   That is, the present invention relates to one type of aromatic vinyl resin (A) obtained by homopolymerization and a copolymer thermoplastic resin (B) 1 obtained by copolymerizing an aromatic vinyl compound and an unsaturated carboxylic acid ester compound. A light diffusing plate obtained by molding a resin composition comprising a mixture of at least one type, wherein the content of the unsaturated carboxylic acid ester compound unit of the thermoplastic copolymer resin (B) is 5 to 80% by weight. The resin composition has a phase separation structure, the total light transmittance of the light diffusion plate is 40 to 70%, the parallel light transmittance is 6.5% or less, and the thickness of the plate is 0.5 to 3 mm. Is a light diffusion plate characterized by

本発明に用いられる芳香族ビニル系樹脂(A)は、芳香族ビニル化合物を単独重合して得られる。共重合熱可塑性樹脂(B)は、不飽和カルボン酸エステルと芳香族ビニル化合物を共重合して得られる。芳香族ビニル系樹脂(A)及び共重合熱可塑性樹脂(B)に用いられるモノマーとしての芳香族ビニル化合物は同一であっても、異なってもよい。   The aromatic vinyl resin (A) used in the present invention is obtained by homopolymerizing an aromatic vinyl compound. The copolymer thermoplastic resin (B) is obtained by copolymerizing an unsaturated carboxylic acid ester and an aromatic vinyl compound. The aromatic vinyl compound as a monomer used in the aromatic vinyl resin (A) and the copolymer thermoplastic resin (B) may be the same or different.

芳香族ビニル化合物としては、スチレン、α‐メチルスチレン、p-メチルスチレン、m-メチルスチレン、o-メチルスチレン、p-メトキシスチレン、o-メトキシスチレン、p-クロロスチレン、o-クロロスチレン、4-ビニルピリジン、2-ビニルピリジンなどが挙げられる。中でも、スチレン、α‐メチルスチレンが好ましく用いられる。共重合熱可塑性樹脂(B)にあっては、これら芳香族ビニル化合物を1種又は2種以上を用いることができる。   Aromatic vinyl compounds include styrene, α-methylstyrene, p-methylstyrene, m-methylstyrene, o-methylstyrene, p-methoxystyrene, o-methoxystyrene, p-chlorostyrene, o-chlorostyrene, 4 -Vinylpyridine, 2-vinylpyridine and the like can be mentioned. Of these, styrene and α-methylstyrene are preferably used. In the copolymer thermoplastic resin (B), one or more of these aromatic vinyl compounds can be used.

共重合熱可塑性樹脂(B)に用いるモノマーとしての不飽和カルボン酸エステル化合物としては、メタクリル酸メチル、メタクリル酸エチル、メタクリル酸イソプロピル、メタクリル酸ブチル、メタクリル酸イソブチル、メタクリル酸t-ブチル、アクリル酸メチル、アクリル酸エチル、アクリル酸イソプロピル、アクリル酸ブチル、アクリル酸イソブチル、アクリル酸t-ブチル、アクリル酸2-エチルヘキシルなどが挙げられる。このうち、好ましくはメタクリル酸メチル、メタクリル酸エチル、メタクリル酸ブチル、メタクリル酸t-ブチルであり、特に好ましくはメタクリル酸メチルである。これら不飽和カルボン酸エステル化合物は1種又は2種以上を用いることができる。また、共重合熱可塑性樹脂中の不飽和カルボン酸エステル化合物に由来する単位の含有量は5〜80重量%の範囲である。   Examples of unsaturated carboxylic acid ester compounds as monomers used in the copolymerized thermoplastic resin (B) include methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, and acrylic acid. Examples include methyl, ethyl acrylate, isopropyl acrylate, butyl acrylate, isobutyl acrylate, t-butyl acrylate, and 2-ethylhexyl acrylate. Of these, methyl methacrylate, ethyl methacrylate, butyl methacrylate, and t-butyl methacrylate are preferable, and methyl methacrylate is particularly preferable. These unsaturated carboxylic acid ester compounds can be used alone or in combination of two or more. Moreover, content of the unit derived from the unsaturated carboxylic ester compound in a copolymerization thermoplastic resin is the range of 5 to 80 weight%.

共重合熱可塑性樹脂(B)としては、上記芳香族ビニル化合物と不飽和カルボン酸エステル化合物を共重合して得られる樹脂があるが、好ましくはスチレン-メタクリル酸メチル共重合樹脂である。   The copolymer thermoplastic resin (B) includes a resin obtained by copolymerizing the above aromatic vinyl compound and an unsaturated carboxylic ester compound, and is preferably a styrene-methyl methacrylate copolymer resin.

本発明において使用される芳香族ビニル系樹脂(A)及び共重合熱可塑性樹脂(B)は、公知の方法により重合して製造することができる。この芳香族ビニル系樹脂(A)及び共重合熱可塑性樹脂(B)の重量平均分子量は、ともに250000〜400000であることが好ましい。250000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。   The aromatic vinyl resin (A) and copolymer thermoplastic resin (B) used in the present invention can be produced by polymerization by a known method. Both the weight average molecular weights of the aromatic vinyl resin (A) and the copolymer thermoplastic resin (B) are preferably 250,000 to 400,000. If it is less than 250,000, 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 colors.

本発明において使用される樹脂組成物は、芳香族ビニル系樹脂(A)を1種及び共重合熱可塑性樹脂(B)を1種以上混合して得られる。本発明で混合する樹脂のうち、少なくとも2種類の樹脂において、不飽和カルボン酸エステル化合物単位の含有量の差が20〜40重量%であることが好ましい。20重量%未満であると相溶性が高く、屈折率差もΔn≦0.02となるため拡散性が悪くなる。また、40重量%を超えると相溶性が低く、透明性が悪くなる。不飽和カルボン酸エステル化合物単位の含有量の差は、共重合熱可塑性樹脂(B)の内、最も不飽和カルボン酸エステル化合物単位の含有量が多い樹脂の不飽和カルボン酸エステル化合物単位の含有量が通常、そのまま含有量の差となる。   The resin composition used in the present invention is obtained by mixing one type of aromatic vinyl resin (A) and one or more types of copolymer thermoplastic resin (B). Among the resins mixed in the present invention, in at least two kinds of resins, the difference in the content of unsaturated carboxylic acid ester compound units is preferably 20 to 40% by weight. If it is less than 20% by weight, the compatibility is high and the refractive index difference is Δn ≦ 0.02, so that the diffusibility is deteriorated. On the other hand, if it exceeds 40% by weight, the compatibility is low and the transparency is deteriorated. The difference in the content of the unsaturated carboxylic acid ester compound unit is the content of the unsaturated carboxylic acid ester compound unit of the resin having the largest content of the unsaturated carboxylic acid ester compound unit in the copolymer thermoplastic resin (B). Usually, it becomes the difference in content as it is.

本発明において使用される樹脂組成物は、光学特性並びに機械強度の物性を満足するためには、芳香族ビニル系樹脂(A)と共重合熱可塑性樹脂(B)が微分散状態で混合する必要がある。すなわち、海島構造を有する相分離構造を有する。ここで、それぞれの相の分散状態は公知の方法、すなわち酸化ルテニウムを用いた染色法により選択的に染色された試料を透過型電子顕微鏡で観察することにより容易に知ることができる(例えば、J.S.Trent,J.I.Scheinbeim and P.R.Couchman,Macromolecules, 16,589(1983)等を参照)。   In the resin composition used in the present invention, the aromatic vinyl resin (A) and the copolymer thermoplastic resin (B) need to be mixed in a finely dispersed state in order to satisfy the physical properties of optical properties and mechanical strength. There is. That is, it has a phase separation structure having a sea-island structure. Here, the dispersion state of each phase can be easily known by observing a sample selectively stained by a known method, that is, a staining method using ruthenium oxide, with a transmission electron microscope (for example, JS Trent, JIScheinbeim and PRCouchman, Macromolecules, 16,589 (1983) etc.).

該樹脂組成物の10000倍に拡大された透過型電子顕微鏡写真像における芳香族ビニル系樹脂(A)と共重合熱可塑性樹脂(B)の界面の長さが1平方μmあたり1.5μm以上であることがよく、好ましくは2.0μm以上である。その上限は9μm以下であることがよく、好ましくは8μm以下である。1.5μm以下では樹脂同士の相溶性が十分でないため、各物性を満足できない。また、9μm以上では相分離構造が微細になり過ぎ、光拡散性が不十分となる。通常、樹脂組成物の相分離構造は、海島構造を有し、島の大きさは直径として0.2〜5μm程度、好ましくは0.5〜1μm程度である。この界面の長さは、ある断面における島と海との界面の長さを断面の面積で除することにより計算される。   The length of the interface between the aromatic vinyl resin (A) and the copolymer thermoplastic resin (B) in the transmission electron micrograph image magnified 10,000 times of the resin composition is 1.5 μm or more per square μm. The thickness is often 2.0 μm or more. The upper limit is preferably 9 μm or less, and preferably 8 μm or less. If the thickness is 1.5 μm or less, the compatibility between the resins is not sufficient, so that each physical property cannot be satisfied. On the other hand, if it is 9 μm or more, the phase separation structure becomes too fine and the light diffusibility becomes insufficient. Usually, the phase separation structure of the resin composition has a sea-island structure, and the size of the island is about 0.2 to 5 μm, preferably about 0.5 to 1 μm in diameter. The length of this interface is calculated by dividing the length of the interface between the island and the sea in a cross section by the area of the cross section.

芳香族ビニル系樹脂(A)と共重合熱可塑性樹脂(B)の混合割合は上記相分離構造を有するように決められる。好ましくは、芳香族ビニル系樹脂(A)30〜70重量%、共重合熱可塑性樹脂(B)70〜30重量%の範囲である。   The mixing ratio of the aromatic vinyl resin (A) and the copolymerized thermoplastic resin (B) is determined so as to have the phase separation structure. Preferably, it is in the range of 30 to 70% by weight of the aromatic vinyl resin (A) and 70 to 30% by weight of the copolymer thermoplastic resin (B).

樹脂組成物には、必要に応じて、本発明の目的を損なわない範囲で、紫外線吸収剤、酸化防止剤、熱安定剤、着色剤、可塑剤、離型剤、帯電防止剤、耐候助剤、内部潤滑剤、外部潤滑剤等の添加剤を1種又は2種以上配合してもよい。   In the resin composition, if necessary, an ultraviolet absorber, an antioxidant, a heat stabilizer, a colorant, a plasticizer, a release agent, an antistatic agent, and a weathering aid, as long as the object of the present invention is not impaired. In addition, one or more additives such as an internal lubricant and an external lubricant may be blended.

本発明の光拡散板の製造方法は、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。例えば、上記樹脂組成物を射出成形、押出し成形等により所定形状に成形することにより得ることができる。   The manufacturing method of the light diffusing plate of the present invention is not particularly limited as long as the object of the present invention can be satisfied. For example, it can be obtained by molding the resin composition into a predetermined shape by injection molding, extrusion molding or the like.

本発明の光拡散板は、厚さが0.5〜3mmのものである。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ず、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。   The light diffusing plate of the present invention has a thickness of 0.5 to 3 mm. If the thickness is less than 0.5 mm, the strength as a diffusion plate for backlight cannot be ensured, and if it exceeds 3 mm, the weight of the diffusion plate increases, so that it cannot cope with an increase in size and thickness.

本発明の光拡散板は、樹脂組成物の層が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。   In the light diffusing plate of the present invention, the resin composition layer 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、全光線透過率が40〜70%、好ましくは50〜70%のものである。全光線透過率が40%未満であると、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。また、全光線透過率が70%を越えると、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。また、平行光線透過率が6.5%以下、好ましくは6%以下のものである。6.5%を超えると光源の隠蔽性に欠けるため、輝度ムラの目立つ光拡散板となる。   The light diffusion plate of the present invention has a total light transmittance of 40 to 70%, preferably 50 to 70%. When the total light transmittance is less than 40%, the amount of transmitted light is insufficient, so that a light diffusion plate with insufficient brightness is obtained. On the other hand, if the total light transmittance exceeds 70%, the light source is not concealed, resulting in a light diffusion plate with noticeable luminance unevenness caused by the image of the backlight light source. The parallel light transmittance is 6.5% or less, preferably 6% or less. If it exceeds 6.5%, the light source is not concealed, resulting in a light diffusion plate with noticeable luminance unevenness.

有利には、2mm厚み換算値としての全光線透過率が40〜70%、好ましくは50〜70%のものである。更に有利には、3mm厚み換算値としての全光線透過率が40〜70%、好ましくは50〜70%のものである。なお、2mm厚み換算値又は3mm厚み換算値は樹脂組成物を2mm厚み又は3mm厚みの板状に成形して測定することもできるし、事前に換算係数を求めるなどして計算で算出することもできる。   Advantageously, the total light transmittance as a converted value of 2 mm thickness is 40 to 70%, preferably 50 to 70%. More advantageously, the total light transmittance as a converted value of 3 mm thickness is 40 to 70%, preferably 50 to 70%. The 2 mm thickness converted value or the 3 mm thickness converted value can be measured by molding the resin composition into a 2 mm or 3 mm thick plate shape, or can be calculated by calculating a conversion coefficient in advance. it can.

本発明の光拡散板は、拡散源を樹脂間の界面とすることで、高輝度、高光拡散であり、軽量化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 diffusing plate of the present invention realizes high brightness and high light diffusion and light weight by using a diffusion source as an interface between resins. Depending on the above, various additives such as antistatic agents, antioxidants, flame retardants, light stabilizers, ultraviolet absorbers and fluorescent brighteners 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、大型化に伴い、軽量化を要求される用途に好適である。   The light diffusing plate of the present invention is used as a diffusing plate for a direct type backlight of a liquid crystal display or a liquid crystal television, for applications where a balance between light diffusing property and light transmitting property is required. It is suitable for applications that require

本発明に係る光拡散板は、屈折率の異なる樹脂を特定の割合で配合させることにより得ることができるため、高輝度、高光拡散性を有し、軽い材料となる。   Since the light diffusing plate according to the present invention can be obtained by blending resins having different refractive indexes at a specific ratio, the light diffusing plate is a light material having high luminance and high light diffusibility.

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、平行光線透過率
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)界面長さ
超薄切片化した後、酸化ルテニウムで染色した。選択的に染色された試料を透過型電子顕微鏡にて写真撮影し、10000倍に拡大された写真を用いて、染色された芳香族ビニル系樹脂部分と染色されない芳香族ビニル化合物と不飽和カルボン酸エステル化合物との共重合熱可塑性樹脂部分との海島構造の界面の長さをそれぞれの島ごとに測定し、これらを合計することで1平方μmあたりの樹脂界面長さの合計を算出した。
The physical properties of the light diffusing plate were evaluated by the following methods.
(1) Total light transmittance, parallel light transmittance It carried out based on the 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) Interface length After ultra-thin sectioning, it was stained with ruthenium oxide. Photographing selectively dyed sample with a transmission electron microscope, and using a photograph magnified 10,000 times, stained aromatic vinyl resin part, unstained aromatic vinyl compound and unsaturated carboxylic acid The length of the interface of the sea-island structure with the copolymerized thermoplastic resin portion with the ester compound was measured for each island, and these were added together to calculate the total resin interface length per square μm.

(1)樹脂組成物の調製
ポリスチレン(G‐15L:東洋スチレン社製、屈折率1.592)、メタクリル酸メチル含20%であるスチレン‐メタクリル酸メチル共重合樹脂(MS‐200:新日鐵化学社製、屈折率1.573)、メタクリル酸メチル含30%であるスチレン‐メタクリル酸メチル共重合樹脂(MS‐300:新日鐵化学社製、屈折率1.564)、メタクリル酸メチル含60%であるスチレン‐メタクリル酸メチル共重合樹脂(MS‐600:新日鐵化学社製、屈折率1.536)のうち2種類以上を、二軸押出機を用いて混練、ペレット化し、目的とする熱可塑性樹脂組成物を得た。
(2)溶融押出成形による拡散板の作製
熱可塑性樹脂組成物を溶融押出成形により、厚さ2mmの拡散板を作製した。
(1) Preparation of resin composition Polystyrene (G-15L: manufactured by Toyo Styrene Co., Ltd., refractive index 1.592), methyl methacrylate-containing 20% styrene-methyl methacrylate copolymer resin (MS-200: Nippon Steel Corporation) Chemical Co., refractive index 1.573), methyl methacrylate containing 30% styrene-methyl methacrylate copolymer resin (MS-300: manufactured by Nippon Steel Chemical Co., Ltd., refractive index 1.564), containing methyl methacrylate Two or more types of 60% styrene-methyl methacrylate copolymer resin (MS-600: manufactured by Nippon Steel Chemical Co., Ltd., refractive index: 1.536) were kneaded and pelletized using a twin screw extruder. A thermoplastic resin composition was obtained.
(2) Preparation of diffusion plate by melt extrusion molding A diffusion plate having a thickness of 2 mm was prepared by melt extrusion molding of the thermoplastic resin composition.

G‐15L、MS‐200、MS‐600を、50:40:10(重量比)の割合で混合し、まずこれを二軸混練機(バレル温度200〜240℃)にて混練押出しペレット化した。次に、Tダイを先端に持つ単軸押出機にペレットを供給して、シート状で2mm厚の拡散板を得た。各種物性測定結果を表1に示す。   G-15L, MS-200, and MS-600 were mixed at a ratio of 50:40:10 (weight ratio), and first, this was kneaded and extruded into a pellet by a biaxial kneader (barrel temperature 200 to 240 ° C.). . Next, pellets were supplied to a single screw extruder having a T-die at the tip to obtain a sheet-like diffusion plate having a thickness of 2 mm. Table 1 shows the measurement results of various physical properties.

G‐15L、MS‐300を40:60(重量比)の割合で混合した以外は、実施例1と同一条件にてシート成形した。各種物性測定結果を表1に示す。   A sheet was molded under the same conditions as in Example 1 except that G-15L and MS-300 were mixed at a ratio of 40:60 (weight ratio). Table 1 shows the measurement results of various physical properties.

G‐15L、MS‐300、MS‐600を50:45:5(重量比)の割合で混合した以外は、実施例1と同一条件にてシート成形した。各種物性測定結果を表1に示す。   A sheet was molded under the same conditions as in Example 1 except that G-15L, MS-300, and MS-600 were mixed at a ratio of 50: 45: 5 (weight ratio). Table 1 shows the measurement results of various physical properties.

比較例1
MS‐200、MS‐300を80:20(重量比)の割合で混合した以外は、実施例1と同一条件にてシート成形した。得られた光拡散板の評価結果を表1に示す。
Comparative Example 1
A sheet was molded under the same conditions as in Example 1 except that MS-200 and MS-300 were mixed at a ratio of 80:20 (weight ratio). The evaluation results of the obtained light diffusion plate are shown in Table 1.

比較例2
G‐15L、MS‐200、MS‐600を40:20:40(重量比)の割合で混合した以外は、実施例1と同一条件にてシート成形した。得られた光拡散板の評価結果を表1に示す。
Comparative Example 2
A sheet was molded under the same conditions as in Example 1 except that G-15L, MS-200, and MS-600 were mixed at a ratio of 40:20:40 (weight ratio). The evaluation results of the obtained light diffusion plate are shown in Table 1.

比較例3
MS−200にシリコーンビーズ1.0重量%を混合後、溶融混練し、押出成形により厚さ2mmのシートとした。得られた光拡散板の評価結果を表1に示す。
Comparative Example 3
MS-200 was mixed with 1.0% by weight of silicone beads, melt-kneaded, and extruded to form a sheet having a thickness of 2 mm. The evaluation results of the obtained light diffusion plate are shown in Table 1.

Figure 2007192861
Figure 2007192861

Claims (5)

単独重合して得られる芳香族ビニル系樹脂(A)1種類と、芳香族ビニル化合物と不飽和カルボン酸エステル化合物を共重合して得られる共重合熱可塑性樹脂(B)1種類以上を混合してなる樹脂組成物を成形して得られる光拡散板であって、熱可塑性共重合樹脂(B)の不飽和カルボン酸エステル化合物単位の含有量が5〜80重量%であり、樹脂組成物が相分離構造を有し、光拡散板の全光線透過率が40〜70%、平行光線透過率が6.5%以下、板の厚さが0.5〜3mmであることを特徴とする光拡散板。   Mix one type of aromatic vinyl resin (A) obtained by homopolymerization and one or more types of copolymer thermoplastic resin (B) obtained by copolymerizing an aromatic vinyl compound and an unsaturated carboxylic acid ester compound. A light diffusing plate obtained by molding the resin composition, wherein the content of the unsaturated carboxylic acid ester compound unit of the thermoplastic copolymer resin (B) is 5 to 80% by weight, and the resin composition is Light having a phase separation structure, light diffusion plate having total light transmittance of 40 to 70%, parallel light transmittance of 6.5% or less, and plate thickness of 0.5 to 3 mm Diffusion plate. 樹脂組成物内の相分離構造における樹脂間の界面の長さの合計が1μm2あたり1.5μm以上であることを特徴とする請求項1記載の光拡散板。 The light diffusion plate according to claim 1, wherein the total length of the interface between the resins in the phase separation structure in the resin composition is 1.5 µm or more per 1 µm 2 . 芳香族ビニル系樹脂(A)の重量平均分子量が250000〜400000、共重合熱可塑性樹脂(B)の重量平均分子量が250000〜400000である請求項1又は2記載の光拡散板。   The light diffusing plate according to claim 1 or 2, wherein the aromatic vinyl resin (A) has a weight average molecular weight of 250,000 to 400,000 and the copolymerized thermoplastic resin (B) has a weight average molecular weight of 250,000 to 400,000. 樹脂組成物を形成する樹脂のうち、少なくとも2種類の樹脂において、不飽和カルボン酸エステル化合物単位の含有量の差が20〜40重量%である請求項1〜3のいずれかに記載の光拡散板。   The light diffusion according to any one of claims 1 to 3, wherein a difference in the content of unsaturated carboxylic acid ester compound units is 20 to 40% by weight in at least two kinds of resins forming the resin composition. Board. 芳香族ビニル系樹脂(A)がポリスチレンであり、共重合熱可塑性樹脂(B)がスチレン−メタクリル酸メチル共重合樹脂である請求項1〜4のいずれかに記載の光拡散板。   The light diffusion plate according to any one of claims 1 to 4, wherein the aromatic vinyl resin (A) is polystyrene, and the copolymer thermoplastic resin (B) is a styrene-methyl methacrylate copolymer resin.
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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010152229A (en) * 2008-12-26 2010-07-08 Toyobo Co Ltd Polyolefin light-diffusing film and polyolefin light-diffusing laminate
JP5252071B2 (en) * 2009-03-02 2013-07-31 東洋紡株式会社 Light diffusing film, laminated sheet thereof and method for producing the same
WO2022196599A1 (en) * 2021-03-19 2022-09-22 富士フイルム株式会社 Film and photosensor

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010152229A (en) * 2008-12-26 2010-07-08 Toyobo Co Ltd Polyolefin light-diffusing film and polyolefin light-diffusing laminate
JP5252071B2 (en) * 2009-03-02 2013-07-31 東洋紡株式会社 Light diffusing film, laminated sheet thereof and method for producing the same
WO2022196599A1 (en) * 2021-03-19 2022-09-22 富士フイルム株式会社 Film and photosensor
EP4310556A4 (en) * 2021-03-19 2024-10-02 Fujifilm Corp Film and photosensor

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