JP4051757B2 - Light diffusing resin composition and sheet-like material using the same - Google Patents
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Description
【０００１】
【発明の属する技術分野】
本発明は光拡散性樹脂組成物に関する。 さらには、通常の電球や蛍光灯と組み合わせて光を物体に照射する際のコントラスト向上に優れ、さらに光拡散性、隠蔽性、光透過性等の光学特性に優れた光拡散性樹脂組成物及びそれを用いてなる光拡散性樹脂シート状物に関する。
【０００２】
【従来の技術】
従来より、照明カバーや透過型ディスプレイ用の光拡散板、照明看板などの部材として、透明性樹脂にその樹脂と屈折率の異なる透明性の無機系や有機系の微粒子を混在させた光拡散性樹脂材料が広く用いられている。
【０００３】
また一方では、透明性樹脂に特定の金属材料を分散させて、特定波長光の選択吸収性を持たせた機能性材料も検討が進んでいる。 数多い金属の中でもネオジムの吸光特性は人間の視感度が最も大きい５８０ｎｍ付近の波長の光を選択的に吸収することが知られている。
近年の照明用光源としては高輝度光源の利用が増加しており、高輝度ランプの演色性と幻惑の防止が望まれている。 防眩方法や演色性向上の手段として５８０ｎｍ近傍の光を吸収することが効果的であることが知られている。
【０００４】
近年、照明器具に使用される光源は、三波長型蛍光灯の高輝度化が進む一方で、飲食店に使用される光源として電球が見直されつつある。 しかしながら電球を光源として使用した場合、落ち着いた雰囲気が得られるものの演色性が低下するとの傾向が見られる。 このため光透過性、光拡散性、隠蔽性等の光学特性を保持したまま特定波長光の選択吸収性を付与する技術が必要となってきた。このような光学特性と選択吸収性を必要とした用途に適した材料の出現が渇望されている状況にある。
特開平４−７２３６１号公報には、透明ポリマー中にネオジム化合物が含有されてなる光選択機能性ビーズを透明樹脂組成物中に分散した光選択機能性樹脂組成物が提案されている。
【０００５】
【発明が解決しようとする課題】
上記公報記載の組成物は、ネオジム化合物を重合時に透明ポリマー中に含有させるもので、光拡散材料として使用するには、光拡散剤を別途加える必要がある。固くて壊れやすい粒子を光拡散剤として用い、押出成形や射出成形のような溶融成形を行うと粒子が押出機内で崩壊して、光拡散板として非常に重要な隠蔽性や光拡散性等の光学特性を大きく損ねてしまう場合がある。
かかる事情下に鑑み、本発明者等は特定波長光の選択吸収性を有し、且つ光学特性に優れた光拡散性樹脂組成物およびこれを用いてなるシート状物を提供することを目的として鋭意検討した結果、ネオジウム化合物を特定量被覆した光拡散剤を樹脂中に分散・含有せしめる場合には上記目的を全て満足し得る樹脂組成物が得られることを見出し、本発明を完成するに至った。
【０００６】
【課題を解決するための手段】
すなわち本発明は、透明性樹脂１００重量部に有機酸ネオジム塩を被覆した平均粒子径が０．５〜５０μｍである光拡散粒子1 〜20重量部が分散してなる光拡散性樹脂組成物を提供するにある。
さらに本発明の他の一つは、透明性樹脂１００重量部に有機酸ネオジム塩を被覆した平均粒子径が０．５〜５０μｍである光拡散粒子1 〜20重量部が分散してなる光拡散性樹脂組成物からなり、厚みが０．８〜５ｍｍで有機酸ネオジム塩を被覆した光拡散粒子を１０〜２００ｇ／ｍ2 分散していることを特徴とする光拡散性樹脂シート状物を提供するにある。
【０００７】
【発明の実施の形態】
以下、本発明を詳細に説明する。
本発明における透明性樹脂とは、スチレン系樹脂、ポリカーボネート、塩化ビニル系樹脂、ポリエステル系樹脂、アクリル系樹脂等が挙げられる。中でも、スチレン系樹脂、ポリカーボネート、アクリル系樹脂が好ましく、アクリル系樹脂がさらに好ましい。
【０００８】
上記におけるアクリル系樹脂とは、メタクリル酸メチル系樹脂のことをいい、その構成単位としてメタクリル酸メチル単位を５０重量％以上含有するものであり、メタクリル酸メチル単位を５０重量％以上含有する限りその一部がメタクリル酸メチルと共重合可能な単官能の不飽和単量体単位で置き換えられたものであってもよい。
【０００９】
メタクリル酸メチルと共重合可能な単官能不飽和単量体としては、例えば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、メタクリル酸フェニル、メタクリル酸ベンジル、メタクリル酸２−エチルヘキシル、メタクリル酸２−ヒドロキシエチル等の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、アクリル酸２−ヒドロキシエチル、等のアクリル酸エステル類、メタクリル酸、アクリル酸などの不飽和酸類、スチレン、α−メチルスチレン、アクリロニトリル、メタクリロニトリル、無水マレイン酸、フェニルマレイミド、シクロヘキシルマレイミド等である。またこの共重合体には、無水グルタル酸単位、グルタルイミド単位をさらに含んでいても良い。
【００１０】
本発明に於いて、光拡散粒子を被覆する有機酸ネオジム塩は、脂肪酸、樹脂酸、スルホン酸、鱗酸等のネオジム塩であり、具体的には、脂肪酸塩として例えば酢酸塩、プロピオン酸塩、酪酸塩、吉草酸塩、カプロン酸塩、カプリル酸塩、オクチル酸塩、ラウリン酸塩、ミリスチン酸塩、パルミチン酸塩、ステアリン酸塩、アラキン酸塩、ベヘン酸塩、リグノセリン酸塩、樹脂酸塩としてアビエチン酸塩、ネオアビエチン酸塩、ｄ−ピマル酸塩、、イソ−ｄ−ピマル酸塩、ポドカルプ酸塩、アガテンジカルボン酸塩、安息香酸塩、ケイ皮酸塩、ｐ−オキシケイ皮酸塩、スルホン酸塩として、アルキルスルホン酸塩、アルキルベンゼンスルホン酸塩、燐酸塩として、燐酸塩、ホスホン酸塩、亜燐酸塩等が挙げられる。これらの中でも〔化１〕に示すような直鎖状の脂肪酸塩が好ましく、さらには〔化１〕におけるｎが２〜１８の範囲のものが好ましく用いられる。
【００１１】
【化１】
〔ＣＨ3 （ＣＨ2 ）n ＣＯＯ〕3 Ｎｄ
【００１２】
本発明に於いて使用する光拡散粒子は、粒子表面で有機酸ネオジム塩と反応が起こるような材料を選択する。このような無機粒子としては炭酸カルシウム、硫酸バリウム、水酸化アルミニウム等が、また有機系粒子としては、表面に水酸基の付いたスチレン系やアクリル系やシロキサン系の架橋または高分子量の樹脂粒子等が挙げられる。これらの材料の中でも、無機粒子は一段の有機酸ネオジム塩の表面処理により選択吸収性が付与できると共に、有機酸ネオジム塩で予め被覆処理することにより溶融成形時に無機粒子の崩壊が生じ難いためか、光拡散効果が大きく向上する。
【００１３】
光拡散粒子の重量平均粒子径は約０．５〜約５０μｍ、好ましくは約１〜約１５μｍである。０．５μｍ未満であると隠蔽性が低下し、５０μｍを超えると光拡散性が不足する他に材料強度を低下させる傾向がある。
【００１４】
光拡散粒子の透明性樹脂への分散量は約１〜約２０重量部、好ましくは約１〜約１０重量部である。１重量部より少ないと選択吸収性が十分でなく、２０重量部を超えると光透過性が不足する他に材料の耐衝撃性が低下する。
【００１５】
またシート状物とした場合はシート厚みを約０．８〜約５ｍｍとした方が一般的である。光拡散粒子の含有量は、該量が同一でもシート厚みによって光拡散性が異なるので、単位面積当たりの量で表わすのが望ましく、約１０〜約２００ｇ／ｍ2 とするのが好ましい。この量が少なすぎると光線透過率は高いものの隠蔽性と光拡散性が共に低く、多すぎると隠蔽性と光拡散性は高いが、光線透過率が低すぎるものとなる。分散のさせ方については、基材樹脂の厚み方向に均一に分散させても、積層板のように表層や中央に局部的に偏在させても良い。
【００１６】
シート状物とした時の選択吸収性評価は５８０ｎｍの吸光度が用いられる。この吸光度は、自記分光光度計により特定波長域を連続的に測定した結果より算出される。６２０ｎｍと５５０ｎｍの光線透過率の平均値をＩとして、５８０ｎｍの透過率をｉとしたときのｌｎ（Ｉ／ｉ）を計算して５８０ｎｍの吸光度としている。この吸光度の値が０．０１〜０．８が望ましい範囲である。
【００１７】
本発明においては、光拡散粒子に有機酸ネオジム塩を被覆し適用することを必須とする。粒子表面に有機酸や有機酸塩を被覆する技術は広く一般的に行われており、代表的な例として、炭酸カルシウムや水酸化アルミニウム等の無機粒子の表面処理技術が挙げられる。表面処理は、粒子表面を特定の有機物で覆って粒子間の凝集を抑える働きの他に、樹脂との親和性を上げる働きもある。
【００１８】
本発明における光拡散性樹脂組成物は、押出機を介して賦形されるものに非常に適している。炭酸カルシウムや水酸化アルミニウムのような無機粒子は、溶融混練前は粒径が揃っていても、押出機を通過させて組成物やシートとした際に粒子同士の接触により崩壊し隠蔽性や光拡散性を損ねるが場合があるが、本発明における光拡散性樹脂組成物は押出機等を通過させた後も隠蔽性や光拡散性の低下はほとんど認められない。また光拡散性粒子の表面にネオジム化合物を集中的に分布させることにより、透明性樹脂へのネオジム化合物の分散が少なくなり、基材樹脂の物性低下を最小限に抑えることができる。
【００１９】
有機酸ネオジム塩の光拡散粒子への被覆量は、該光拡散粒子１００重量部に対して約１〜約３００重量部である。１重量部より少ないと選択吸収性が不十分で、３００重量部を超えると基材の透明樹脂中に有機酸ネオジム塩が多く分散してしまうため好ましくない。被覆量は無機粒子の場合ではモル量で算出した方が好ましく、光拡散粒子１モルに対して有機酸ネオジム塩を約０．０１〜約１モルが適当である。
【００２０】
光拡散粒子表面に有機酸ネオジム塩を被覆させる手段としては、公知の方法、すなわち乾式法、湿式法があり特に制限されないが、例えば、乾式法はヘンシェルミキサー等で光拡散粒子を攪拌して加温状況下で有機酸ネオジム塩を投入し粒子表面に被覆する方法であり、湿式法は光拡散粒子のスラリー中に有機酸ネオジム塩を投入して、光拡散粒子の表面に吸着・被覆させる方法が適用される。
【００２１】
透明樹脂に有機ネオジムを被覆した光拡散粒子を分散させて組成物とするには、周知の熱可塑性樹脂組成物の製法が適用できる。例えば溶融混練方法が挙げられる。溶融混練は一般的に使用されている一軸または二軸の押出機、各種のニーダー等の混練装置を用いる方法がある。さらに透明性樹脂がアクリル系樹脂やスチレン系樹脂の場合は、これら透明性樹脂を構成する単量体及びその部分重合体を含むシロップに混合して、キャスト重合、連続キャスト重合させて一段でシート状物とする方法もある。
【００２２】
本発明における光拡散性樹脂シート状物とは、いわゆるシート、板と称されるものである。また、樹脂板の形状は、厚みの均一なものでも、厚みに分布があるものでも、湾曲していても構わない。
該光拡散性樹脂組成物をシート状物とするには、一軸、二軸の押出機等で溶融混練した後、Ｔダイ、ロールユニットを介してシート状に加工したり、射出成形やプレス成形によりシート状にする周知の方法が適用し得る。
【００２３】
また、本発明の光拡散性樹脂組成物に、染料、艶消し剤、光安定剤、紫外線吸収剤、酸化防止剤、離型剤、難燃剤、帯電防止剤等周知の添加剤を添加しても特に問題は無い。
【００２４】
【発明の効果】
本発明の光拡散性樹脂組成物は、剪断力のかかる加熱溶融成形加工、例えば押出成形や射出成形を行った後も、５８０ｎｍ近傍の光を吸収する演色性効果を有すると共に、光線透過率や光拡散性、隠蔽性等の光学特性に優れた成形品を提供することを可能ならしめたもので、自動車等のメーターパネル、照明カバー、看板、透過型ディスプレイの光拡散板、発光式スイッチボタンなどの各種成形品等の多岐の用途に適用し得ることより、その産業上の利用価値は頗る大である。
【００２５】
【実施例】
以下実施例によって本発明を更に詳しく説明するが、本発明はこれら実施例によってなんら制限されるものではない。尚、本発明における評価方法は次の通りである。
（１）平均粒子径：光回折散乱粒径測定機〔日機装（株）製、マイクロトラック粒度分析計 Ｍｏｄｅｌ ９２２０ ＦＲＡ〕で測定し、Ｄ５０の値を平均粒子径とした。
（２）全光線透過率（Ｔｔ）：ＪＩＳ Ｋ−７３６１に準拠して、ヘイズ・透過・反射率計（村上色彩技術研究所製ＨＲ−１００）により測定した。
（３）隠蔽性及び光拡散性：垂直入射光による透過角０度の透過光強度（Ｉ０）、垂直入射光による透過角５度の透過光強度（Ｉ５）、垂直入射光による透過角７０度の透過光強度（Ｉ７０）を（株) 村上色彩技術研究所製ＧＰ−１Ｒを用いて測定し、Ｉ５／Ｉ０を隠蔽性とし、Ｉ７０／Ｉ０を光拡散性とした。
（４）加熱延伸成形：３０ｃｍ×２０ｃｍの押出板を、両面より遠赤パネルヒーターで表面温度を１７０℃に加熱し、突上げ成形機（大阪板機製作所製ＴＦ−３００型、突上げ面積１０ｃｍ×５ｃｍ、突上げ高さ１０ｃｍ）を用いて成形品を得た。
（５）成形品光学性能：１７０℃において成形を行った突上げ成形品の側面の箇所を切り出して、全光線透過率、隠蔽性、光拡散性の測定を行った。
（６）光線透過率分布および５８０ｎｍにおける吸光度：日立製３４１０型自記分光光度計に積分球を取付け、３５０〜７８０ｎｍ領域の光線透過率分布を測定した。 また、５８０ｎｍにおける吸光度は６２０ｎｍと５５０ｎｍの光線透過率の平均値をＩとし、５８０ｎｍの透過率をｉとしたときのｌｎ（Ｉ／ｉ）を計算し吸光度とした。
【００２６】
なお実施例で使用した押出装置は以下の通りである。
・押出機：スクリュー径40mm、一軸、田辺プラスチック（株）製・Ｔダイ：幅２０ｍｍ、リップ間隔５ｍｍ・ロール：ポリシングロール３本、縦型
【００２７】
参考例１〜６
有機酸ネオジム塩被覆光拡散粒子として、炭酸カルシウム（ＣＵＢＥ３０Ａ、丸尾カルシウム（株) 製、平均粒子径４．３μｍ）、水酸化アルミニウム（ＣＷ３２５ＬＶ、住友化学工業（株) 製、平均粒子径２５μｍ）を用い、該無機粒子各１００重量部と、有機酸ネオジム塩として、カプリル酸ネオジムとラウリル酸ネオジム（いずれも浅田化学（株）製）を表１に示す量をヘンシェルミキサーで混合し、無機粒子表面に有機酸ネオジムを被覆した。
【００２８】
【表１】
実施例１〜５、比較例１
メタクリル酸メチル系樹脂として、メタクリル酸メチル（９４重量％）とアクリル酸メチル（６重量％）の単量体混合物を懸濁重合して得た共重合体のビーズ１００重量部に、表２に示す量の参考例１〜６で調整した有機酸ネオジム塩を被覆した光拡散粒子をヘンシェルミキサーで混合した後、一軸押出機（スクリュー径４０ｍｍ、田辺プラスチック（株）製）に投入し、樹脂温度２６５℃でペレット化した。得られたペレットを押出機に投入し、樹脂温度２６５℃で、２ｍｍ厚、巾２０ｃｍのシートを作成後、加熱延伸成形を行った。評価結果を表２に示す。
【００３０】
比較例２
実施例１と同じメタクリル酸メチル系樹脂１００重量部とカプリル酸ネオジム３重量部をヘンシェルミキサーで混合した後、一軸押出機（スクリュー径４０ｍｍ、田辺プラスチック（株）製）に投入し、樹脂温度２６５℃でペレット化した。得られたペレット３３重量％と実施例１と同じメタクリル酸メチル系樹脂６７重量％を合わせて１００重量部とした樹脂組成物に対し、参考例１で使用した炭酸カルシウムを１重量部を加え、ヘンシェルミキサーで混合し、前述の一軸押出機に投入し、樹脂温度２６５℃でペレット化した。
得られたペレットを押出機に投入し、樹脂温度２６５℃で、２ｍｍ厚、巾２０ｃｍのシートを作成後、加熱延伸成形を行った。 評価結果を表２に示す。
【００３１】
【表２】
BACKGROUND OF THE INVENTION
The present invention relates to a light diffusing resin composition. Furthermore, it is excellent in contrast improvement when irradiating an object with light in combination with a normal light bulb or fluorescent lamp, and further has a light diffusing resin composition excellent in optical properties such as light diffusing property, concealing property and light transmitting property, and The present invention relates to a light diffusing resin sheet-like material using the same.
[0002]
[Prior art]
Conventionally, as a member for lighting covers, light diffusing plates for transmissive displays, lighting signs, etc., light diffusibility in which transparent inorganic and organic fine particles having a refractive index different from that of resin are mixed in transparent resin Resin materials are widely used.
[0003]
On the other hand, a functional material in which a specific metal material is dispersed in a transparent resin to give selective absorption of light having a specific wavelength is also being studied. Among many metals, it is known that neodymium has a light absorption characteristic that selectively absorbs light having a wavelength near 580 nm, which has the highest human visibility.
As a light source for illumination in recent years, use of a high-intensity light source is increasing, and it is desired to prevent color rendering and dazzling of a high-intensity lamp. It is known that it is effective to absorb light in the vicinity of 580 nm as an antiglare method and a means for improving color rendering.
[0004]
In recent years, light sources used in lighting fixtures have been increasing in brightness of three-wavelength fluorescent lamps, while light bulbs are being reviewed as light sources used in restaurants. However, when a light bulb is used as a light source, a calm atmosphere is obtained, but there is a tendency that the color rendering is lowered. For this reason, there has been a need for a technique for providing selective absorption of specific wavelength light while maintaining optical characteristics such as light transmission, light diffusibility, and concealment. There is a demand for the appearance of materials suitable for applications that require such optical characteristics and selective absorption.
Japanese Laid-Open Patent Publication No. 4-72361 proposes a photoselective functional resin composition in which photoselective functional beads containing a neodymium compound in a transparent polymer are dispersed in a transparent resin composition.
[0005]
[Problems to be solved by the invention]
The composition described in the above publication contains a neodymium compound in a transparent polymer at the time of polymerization. To use it as a light diffusing material, it is necessary to add a light diffusing agent separately. Hard and fragile particles are used as a light diffusing agent, and when melt molding such as extrusion molding or injection molding, the particles collapse in the extruder, which is very important as a light diffusion plate, such as concealment and light diffusibility. The optical characteristics may be greatly impaired.
In view of such circumstances, the present inventors have an object of providing a light diffusing resin composition having selective absorption of light of a specific wavelength and excellent in optical properties and a sheet-like material using the same. As a result of intensive studies, it was found that when a light diffusing agent coated with a specific amount of a neodymium compound is dispersed and contained in a resin, a resin composition that can satisfy all of the above objects can be obtained, and the present invention has been completed. It was.
[0006]
[Means for Solving the Problems]
That is, the present invention provides a light diffusing resin composition obtained by dispersing 1 to 20 parts by weight of light diffusing particles having an average particle diameter of 0.5 to 50 μm obtained by coating 100 parts by weight of a transparent resin with an organic acid neodymium salt. In offer.
Still another aspect of the present invention is that light diffusion is obtained by dispersing 1 to 20 parts by weight of light diffusing particles having an average particle diameter of 0.5 to 50 μm obtained by coating 100 parts by weight of a transparent resin with an organic acid neodymium salt. A light diffusing resin sheet comprising 10 to 200 g / m 2 of light diffusing particles made of a curable resin composition and having a thickness of 0.8 to 5 mm and coated with an organic acid neodymium salt There is.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
Examples of the transparent resin in the present invention include styrene resins, polycarbonates, vinyl chloride resins, polyester resins, acrylic resins, and the like. Of these, styrene resins, polycarbonates, and acrylic resins are preferable, and acrylic resins are more preferable.
[0008]
The acrylic resin in the above refers to a methyl methacrylate-based resin, which contains 50% by weight or more of methyl methacrylate units as a constituent unit thereof, as long as it contains 50% by weight or more of methyl methacrylate units. A part thereof may be replaced with a monofunctional unsaturated monomer unit copolymerizable with methyl methacrylate.
[0009]
Monofunctional unsaturated monomers copolymerizable with methyl methacrylate include, for example, ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-ethylhexyl methacrylate, 2-hydroxy methacrylate Methacrylic acid esters such as ethyl, acrylic acid esters such as methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, etc. , Unsaturated acids such as methacrylic acid and acrylic acid, styrene, α-methylstyrene, acrylonitrile, methacrylonitrile, maleic anhydride, phenylmaleimide, cyclohexylmaleimide and the like. The copolymer may further contain a glutaric anhydride unit and a glutarimide unit.
[0010]
In the present invention, the organic acid neodymium salt that coats the light diffusing particles is a neodymium salt such as fatty acid, resin acid, sulfonic acid, and scale acid. Specifically, examples of the fatty acid salt include acetate and propionate. , Butyrate, valerate, caprate, caprylate, octylate, laurate, myristate, palmitate, stearate, arachinate, behenate, lignocerate, resin acid Abietic acid salt, neo abietic acid salt, d-pimaric acid salt, iso-d-pimalic acid salt, podocarpic acid salt, agatendicarboxylate, benzoic acid salt, cinnamic acid salt, p-oxycinnamic acid Examples of the salt and sulfonate include alkyl sulfonate, alkyl benzene sulfonate, and phosphate include phosphate, phosphonate, phosphite, and the like. Among these, linear fatty acid salts as shown in [Chemical Formula 1] are preferred, and those having n in the range of [Chemical Formula 1] in the range of 2 to 18 are preferably used.
[0011]
[Chemical 1]
[CH 3 (CH 2 ) n COO] 3 Nd
[0012]
For the light diffusing particles used in the present invention, a material that reacts with the organic acid neodymium salt on the particle surface is selected. Examples of such inorganic particles include calcium carbonate, barium sulfate, and aluminum hydroxide. Examples of organic particles include styrene-based, acrylic-based, and siloxane-based crosslinked or high-molecular weight resin particles having a hydroxyl group on the surface. Can be mentioned. Among these materials, the inorganic particles can be imparted with selective absorbency by the surface treatment of one-step organic acid neodymium salt, and it is difficult to cause the inorganic particles to collapse during melt molding by pre-coating with the organic acid neodymium salt. The light diffusion effect is greatly improved.
[0013]
The weight average particle size of the light diffusing particles is about 0.5 to about 50 μm, preferably about 1 to about 15 μm. When the thickness is less than 0.5 μm, the concealing property is lowered, and when it exceeds 50 μm, the light diffusibility is insufficient and the material strength tends to be lowered.
[0014]
The amount of the light diffusion particles dispersed in the transparent resin is about 1 to about 20 parts by weight, preferably about 1 to about 10 parts by weight. If the amount is less than 1 part by weight, the selective absorption is not sufficient, and if it exceeds 20 parts by weight, the light resistance is insufficient and the impact resistance of the material is lowered.
[0015]
When a sheet-like material is used, the sheet thickness is generally about 0.8 to about 5 mm. The content of the light diffusing particles is desirably expressed as an amount per unit area since the light diffusibility varies depending on the sheet thickness even if the amount is the same, and is preferably about 10 to about 200 g / m 2 . If the amount is too small, the light transmittance is high, but the concealability and light diffusibility are both low. If the amount is too large, the concealability and light diffusibility are high, but the light transmittance is too low. Regarding the method of dispersion, it may be uniformly dispersed in the thickness direction of the base resin, or may be locally unevenly distributed on the surface layer or in the center like a laminated plate.
[0016]
The absorbance at 580 nm is used for selective absorptivity evaluation when a sheet is used. This absorbance is calculated from the result of continuously measuring a specific wavelength range with a self-recording spectrophotometer. The average value of the light transmittance at 620 nm and 550 nm is I, and ln (I / i) where i is the transmittance at 580 nm is calculated as the absorbance at 580 nm. The absorbance value is preferably in the range of 0.01 to 0.8.
[0017]
In the present invention, it is essential that the light diffusing particles are coated with an organic acid neodymium salt. A technique for coating the particle surface with an organic acid or an organic acid salt is widely used, and representative examples include a surface treatment technique for inorganic particles such as calcium carbonate and aluminum hydroxide. The surface treatment has a function of increasing the affinity with the resin in addition to the function of covering the particle surface with a specific organic substance to suppress aggregation between the particles.
[0018]
The light diffusing resin composition in the present invention is very suitable for those shaped through an extruder. Even if the inorganic particles such as calcium carbonate and aluminum hydroxide have the same particle size before melt-kneading, they are collapsed by contact between the particles when passed through an extruder to form a composition or sheet, so that the concealability and light Although the diffusibility may be impaired, the light diffusing resin composition in the present invention hardly shows a decrease in concealability or light diffusibility even after passing through an extruder or the like. In addition, by intensively distributing the neodymium compound on the surface of the light diffusing particles, the dispersion of the neodymium compound in the transparent resin is reduced, and the physical property deterioration of the base resin can be minimized.
[0019]
The coating amount of the organic acid neodymium salt on the light diffusing particles is about 1 to about 300 parts by weight with respect to 100 parts by weight of the light diffusing particles. If the amount is less than 1 part by weight, the selective absorbability is insufficient, and if it exceeds 300 parts by weight, a large amount of organic acid neodymium salt is dispersed in the transparent resin of the substrate, which is not preferable. In the case of inorganic particles, the coating amount is preferably calculated as a molar amount, and about 0.01 to about 1 mol of the organic acid neodymium salt is appropriate for 1 mol of the light diffusing particles.
[0020]
The means for coating the surface of the light diffusing particles with the organic acid neodymium salt is not particularly limited, and there are known methods, that is, dry methods and wet methods. For example, the dry method is performed by stirring the light diffusing particles with a Henschel mixer or the like. The organic acid neodymium salt is charged and coated on the particle surface under temperature conditions. The wet method is a method in which the organic acid neodymium salt is charged into the light diffusing particle slurry and adsorbed and coated on the surface of the light diffusing particle. Applies.
[0021]
In order to disperse light diffusing particles coated with organic neodymium in a transparent resin to obtain a composition, a known method for producing a thermoplastic resin composition can be applied. An example is a melt kneading method. The melt kneading includes a method using a kneading apparatus such as a commonly used single-screw or twin-screw extruder and various kneaders. Furthermore, when the transparent resin is an acrylic resin or a styrene resin, it is mixed with a syrup containing the monomers constituting the transparent resin and a partial polymer thereof, cast polymerized, and continuously cast polymerized to form a sheet in one step. There is also a method of making a product.
[0022]
The light diffusing resin sheet-like material in the present invention is a so-called sheet or plate. Further, the shape of the resin plate may be uniform in thickness, distributed in thickness, or curved.
In order to make the light diffusing resin composition into a sheet, it is melt-kneaded with a uniaxial or biaxial extruder, etc., and then processed into a sheet via a T-die or a roll unit, or injection molding or press molding. A known method for forming a sheet can be applied.
[0023]
In addition, well-known additives such as dyes, matting agents, light stabilizers, ultraviolet absorbers, antioxidants, mold release agents, flame retardants, antistatic agents are added to the light diffusing resin composition of the present invention. There is no particular problem.
[0024]
【The invention's effect】
The light diffusing resin composition of the present invention has a color rendering effect of absorbing light in the vicinity of 580 nm even after performing heat-melt molding processing, such as extrusion molding or injection molding, which requires shearing force, It is possible to provide molded products with excellent optical properties such as light diffusibility and concealment, such as meter panels for automobiles, lighting covers, signboards, light diffusers for transmissive displays, and light-emitting switch buttons. Since it can be applied to a wide variety of uses such as various molded articles, the industrial utility value is enormous.
[0025]
【Example】
Hereinafter, the present invention will be described in more detail by way of examples. However, the present invention is not limited to these examples. The evaluation method in the present invention is as follows.
(1) Average particle diameter: Measured with a light diffraction / scattering particle size measuring instrument [manufactured by Nikkiso Co., Ltd., Microtrac particle size analyzer Model 9220 FRA], and the value of D50 was defined as the average particle diameter.
(2) Total light transmittance (Tt): Measured with a haze / transmittance / reflectometer (HR-100, manufactured by Murakami Color Research Laboratory) in accordance with JIS K-7361.
(3) Concealment and light diffusivity: transmitted light intensity (I0) at a transmission angle of 0 ° by normal incident light, transmitted light intensity (I5) at a transmission angle of 5 ° by normal incident light, and transmission angle at 70 ° by normal incident light Was measured using GP-1R manufactured by Murakami Color Research Laboratory Co., Ltd., and I5 / I0 was concealed and I70 / I0 was light diffusive.
(4) Heat-stretch molding: A 30 cm × 20 cm extruded plate is heated to a surface temperature of 170 ° C. with a far-infrared panel heater from both sides, and a push-up molding machine (TF-300 type manufactured by Osaka plate machine factory, push-up area 10 cm) A molded product was obtained using × 5 cm and a lifting height of 10 cm).
(5) Optical performance of the molded product: A part of the side surface of the push-up molded product molded at 170 ° C. was cut out, and the total light transmittance, concealability and light diffusivity were measured.
(6) Light transmittance distribution and absorbance at 580 nm: An integrating sphere was attached to a Hitachi 3410 self-recording spectrophotometer, and the light transmittance distribution in the 350 to 780 nm region was measured. Absorbance at 580 nm was calculated as ln (I / i) where the average value of the light transmittance at 620 nm and 550 nm was I, and the transmittance at 580 nm was i.
[0026]
In addition, the extrusion apparatus used in the Example is as follows.
・ Extruder: Screw diameter 40mm, uniaxial, manufactured by Tanabe Plastics Co., Ltd. ・ T die: width 20mm, lip interval 5mm ・ Roll: 3 polishing rolls, vertical type
Reference Examples 1-6
As organic acid neodymium salt-coated light diffusing particles, calcium carbonate (CUBE30A, manufactured by Maruo Calcium Co., Ltd., average particle size 4.3 μm), aluminum hydroxide (CW325LV, manufactured by Sumitomo Chemical Co., Ltd., average particle size 25 μm) are used. Using 100 parts by weight of each of the inorganic particles, and mixing neodymium caprylate and neodymium laurate (both manufactured by Asada Chemical Co., Ltd.) as Table 1 with a Henschel mixer, the inorganic particle surface Was coated with neodymium organic acid.
[0028]
[Table 1]
Examples 1-5, Comparative Example 1
As a methyl methacrylate resin, 100 parts by weight of copolymer beads obtained by suspension polymerization of a monomer mixture of methyl methacrylate (94% by weight) and methyl acrylate (6% by weight) are shown in Table 2. After mixing the light diffusion particles coated with the organic acid neodymium salt prepared in Reference Examples 1 to 6 in the amount shown by a Henschel mixer, the mixture was put into a single screw extruder (screw diameter: 40 mm, manufactured by Tanabe Plastics Co., Ltd.), and the resin temperature Pelletized at 265 ° C. The obtained pellets were put into an extruder, and a sheet having a thickness of 2 mm and a width of 20 cm was prepared at a resin temperature of 265 ° C., and then heat stretch molding was performed. The evaluation results are shown in Table 2.
[0030]
Comparative Example 2
After mixing 100 parts by weight of the same methyl methacrylate resin as in Example 1 and 3 parts by weight of neodymium caprylate with a Henschel mixer, the mixture was put into a single screw extruder (screw diameter: 40 mm, manufactured by Tanabe Plastics Co., Ltd.), and the resin temperature was 265. Pelletized at 0 ° C. 1 part by weight of calcium carbonate used in Reference Example 1 was added to the resin composition in which 33% by weight of the pellets and 67% by weight of the same methyl methacrylate resin as in Example 1 were combined to make 100 parts by weight. The mixture was mixed with a Henschel mixer, charged into the single screw extruder described above, and pelletized at a resin temperature of 265 ° C.
The obtained pellets were put into an extruder, a sheet having a thickness of 2 mm and a width of 20 cm was prepared at a resin temperature of 265 ° C., and then heat stretch molding was performed. The evaluation results are shown in Table 2.
[0031]
[Table 2]
Claims (4)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11960798A JP4051757B2 (en) | 1998-04-28 | 1998-04-28 | Light diffusing resin composition and sheet-like material using the same |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11960798A JP4051757B2 (en) | 1998-04-28 | 1998-04-28 | Light diffusing resin composition and sheet-like material using the same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH11310717A JPH11310717A (en) | 1999-11-09 |
| JP4051757B2 true JP4051757B2 (en) | 2008-02-27 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP11960798A Expired - Fee Related JP4051757B2 (en) | 1998-04-28 | 1998-04-28 | Light diffusing resin composition and sheet-like material using the same |
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| Country | Link |
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| JP (1) | JP4051757B2 (en) |
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| JPH11310717A (en) | 1999-11-09 |
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