JP2004269653A - Light diffusing agent for synthetic resin film and light diffusing resin film using the light diffusing agent - Google Patents
Light diffusing agent for synthetic resin film and light diffusing resin film using the light diffusing agent Download PDFInfo
- Publication number
- JP2004269653A JP2004269653A JP2003061294A JP2003061294A JP2004269653A JP 2004269653 A JP2004269653 A JP 2004269653A JP 2003061294 A JP2003061294 A JP 2003061294A JP 2003061294 A JP2003061294 A JP 2003061294A JP 2004269653 A JP2004269653 A JP 2004269653A
- Authority
- JP
- Japan
- Prior art keywords
- light diffusing
- weight
- resin film
- calcium
- diffusing agent
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Abstract
Description
【０００１】
【発明の属する技術分野】
本発明は、合成樹脂フィルム用光拡散剤及びこれを用いた光拡散性樹脂フィルムに関し、更に詳しくは、特に、液晶ディスプレイのバックライト、照明装置等に用いられる光拡散性樹脂フィルムに好適な光拡散剤及び該光拡散剤を用いた光拡散性樹脂フィルムに関するものである。
【０００２】
【従来の技術】
従来から、パソコンやテレビ等の液晶ディスプレイに使用される表示装置は、液晶パネル裏側からバックライトを使用して液晶表示している。該バックライトの方式としては、光源が液晶パネルの真下に配置される直下型と、光源が液晶パネルの端に配置されるサイドライト型の二つに大別できる。前者の直下型は、テレビモニターのような高輝度を必要とする用途に使用され、後者のサイドライト型は、薄型ノートパソコンや低消費電力を必要とする用途に使用されている。特に後者のサイドライト型は、薄型化や低消費電力化が可能であることと、液晶ディスプレイの大型化が進むとともに、直下型に近い高輝度化の検討が各方面でなされており、特に高輝度化における重要部材の一つである光拡散フィルム（図１、２参照）の改良は必要不可欠な要素である。
【０００３】
光拡散フィルムの機能としては、光線透過率や光拡散性を向上させ、正面輝度や視野角を向上させる粒子を含有した透明樹脂フィルムが求められている。該光拡散フィルムの製法としては、古くは透明樹脂フィルムに、硫酸バリウムや酸化チタン、炭酸カルシウムなどの無機化合物を使用していたが硫酸バリウムや酸化チタンは光線透過率よりも拡散性が必要以上に高く、また炭酸カルシウムは天然の重質炭酸カルシウムを粉砕・分級したものであるため、粒子の均一性や分散性が低く、液晶の高画質化に十分に対応することができない（例えば特許文献１、２参照）。そこで、現在は真球状のポリマービーズを用い、該ビーズの持つレンズ効果機能を利用しているケースが主流である。
【０００４】
【特許文献１】
特開昭３−７８７０１号公報
【特許文献２】
特開平６−１５５６７４号公報
【０００５】
しかしながら、ポリマービーズは無機粒子に比べ、耐熱性、耐薬品性等が劣るために、形状安定性の面等で混練機を用いて樹脂中に練り込む方法は難しく、樹脂フィルムに後加工でコーティングする（ビーズコーティング）方式をとらざるを得ない。しかるに、コーティング方式の場合、後加工であるため工程が２度手間になることと、歩留まりも極めて悪くランニングコストが極めて高くなるという問題をはらんでいる。また、物性面でも膜圧のムラが出来やすいために、光学特性が不均一なりなりやすく、例えば樹脂フィルムの薄膜化に対応でき難いなど問題を抱えている。
【０００６】
【発明が解決しようとする課題】
本発明は、こうような実情に鑑みなされたもので、ポリマービーズ並の光拡散性と高い光線透過率を有するとともに、コーティング装置を新設することなく従来の混練り装置を使用して樹脂とのコンパウンド化が可能な、低コストで製造できる無機粒子からなる合成樹脂フィルム用光拡散剤を提供することを目的とする。
【０００７】
【課題を解決するための手段】
本発明者等は、上記目的を達成するため鋭意研究した結果、特定の粒度を持つカルシウム系無機粒子を用いることにより、前記した課題を解決することを見出し本発明を完成するに至った。
【０００８】
即ち、本発明の請求項１に係る発明は、下記の式（ａ）及び（ｂ）を満足したカルシウム系無機化合物からなることを特徴とする合成樹脂フィルム用光拡散剤を内容とするものである。
（ａ） ０．１≦ｄ５０≦５ （μｍ）
（ｂ） ０≦α＜２
但し、
ｄ５０：レーザー回折式（マイクロトラックＦＲＡ）における粒度分布において、大きな粒子側から起算した重量累計５０重量％平均粒子直径（μｍ ）
α ：カルシウム系無機粒子の均一性を示し、α＝（ｄ９０−ｄ１０）／ｄ５０で表される。
ｄ９０：レーザー回折式（マイクロトラックＦＲＡ）における粒度分布において、大きな粒子側から起算した重量累計９０重量％平均粒子直径（μｍ ）
ｄ１０：レーザー回折式（マイクロトラックＦＲＡ）における粒度分布において、大きな粒子側から起算した重量累計１０重量％平均粒子直径（μｍ ）
【０００９】
本発明の請求項２に係る発明は、更に、下記の式（ｃ）を満足することを特徴とする請求項１記載の合成樹脂フィルム用光拡散剤である。
（ｃ） １≦β＜２
但し、
β ：カルシウム系無機粒子の分散性を示し、β＝ｄ５０／Ｄｓｅｍ５０で表される。
Ｄｓｅｍ５０：電子顕微鏡（ＳＥＭ）で観察した、カルシウム系無機粒子の平均直径
【００１０】
本発明の請求項３に係る発明は、カルシウム系無機粒子が、リン酸カルシウム、炭酸カルシウム又はこれらの混合物からなることを特徴とする請求項１又は２記載の合成樹脂フィルム用光拡散剤である。
【００１１】
本発明の請求項４に係る発明は、カルシウム系無機粒子がカルボン酸系重合物、縮合リン酸系無機物、有機リン酸エステル系化合物、飽和・不飽和脂肪酸系化合物より選ばれた少なくとも１種の表面処理剤で被覆されていることを特徴とする請求項１、２又は３記載の合成樹脂フィルム用光拡散剤である。
【００１２】
本願発明の請求項５に係る発明は、請求項１〜４のいずれか１項に記載の光拡散剤を透明熱可塑性樹脂１００重量部に対し、５〜３０重量部配合してなることを特徴とする光拡散性樹脂フィルムである。
【００１３】
【本発明の実施の形態】
以下、本発明を詳細に説明する。
本発明の合成樹脂フィルム用光拡散剤を構成するカルシウム系無機粒子は、難溶性のカルシウム系無機粒子であれば特に制限されず、例えば、炭酸カルシウム、リン酸カルシウム、硫酸カルシウム、珪酸カルシウム、水酸化カルシウム、カルシウム系ハイドロタルサイト等が例示できる。中でも炭酸カルシウム（カルサイト）やリン酸カルシウム（ハイドロキシアパタイト）は、結晶安定性が高く、また光の屈折率が樹脂と近似しているため、透明性において樹脂フィルムとの相性が良好の上、光線透過率や光拡散性の点で優れている。一方、酸化チタン、酸化亜鉛、アルミナ、硫酸バリウム等の無機粒子は、光の吸収性や拡散性が強過ぎるために、本発明で求められる光学物性を得ることは困難である。
【００１４】
また、前記したカルシウム系無機粒子は、下記の（ａ）式と（ｂ）式を満足することが必要である。
（ａ） ０．１≦ｄ５０≦５ （μｍ）
（ｂ） ０≦α＜２
但し、
ｄ５０：レーザー回折式（マイクロトラックＦＲＡ）における粒度分布において、大きな粒子側から起算した重量累計５０重量％平均粒子直径（μｍ ）
α ：カルシウム系無機粒子の均一性を示し、α＝（ｄ９０−ｄ１０）／ｄ５０で表される。
ｄ９０：レーザー回折式（マイクロトラックＦＲＡ）における粒度分布において、大きな粒子側から起算した重量累計９０重量％平均粒子直径（μｍ ）
ｄ１０：レーザー回折式（マイクロトラックＦＲＡ）における粒度分布において、大きな粒子側から起算した重量累計１０重量％平均粒子直径（μｍ ）
【００１５】
（ａ）式は、本発明のカルシウム系無機粒子を粒度分布測定機器で計測した平均粒子径（ｄ５０）が、０．１〜５μｍであることが必要である。０．１μｍ未満の場合、分子間力等の影響で粒子の分散性が極端に低下するため、安定した光拡散性を得ることができない。５μｍを越えると、所望の光学物性を得るには添加量を増やす必要性があるが、添加量を増やすと樹脂フィルム表面の凹凸が目立ち光散乱のムラを生じてしまう。従って、好ましくは０．３〜３μｍ、より好ましくは０．５〜２μｍである。
【００１６】
（ｂ）式は、本発明のカルシウム無機粒子の均一性を示す値であり、０〜２未満である必要がある。該粒子のα（均一性）が、上限値を越える程の不均一性であると、均一な光学物性を得ることができず、本発明の目的である高輝度化を達成することができない。従って、好ましくは０〜１．５、より好ましくは０〜１である。
【００１７】
尚、（ａ）式や（ｂ）式で算出する粒度分布測定条件は下記に示す。
下記の如く炭酸カルシウム試料と水を１４０ｍｌマヨネーズ瓶に秤量したものをレーザー回折式粒度分布計（ＦＲＡ：マイクトロラック社製）により測定を行う。
尚、予備分散として用いる超音波分散は、一定条件で行う方が好ましく、本発明で用いる超音波分散機は、ＵＳ−３００Ｔ（日本精機製作所社製）を用い、電流値３００μＡの下、６０秒間の一定条件で予備分散させる。
（粒度測定用懸濁液の配合）
（Ｉ）カルシウム系無機粒子 ５ｇ
（ＩＩ）メタノール ５０ｇ
【００１８】
本発明の光拡散剤は、前記した（ａ）式と（ｂ）式の他に、更に下記の（ｃ）式を満足することが好ましい。
（ｃ） １≦β＜２
但し、
β ：カルシウム系無機粒子の分散性を示し、β＝ｄ５０／Ｄｓｅｍ５０で表される。
Ｄｓｅｍ５０：電子顕微鏡（ＳＥＭ）で観察した、カルシウム系無機粒子の平均粒子直径。
【００１９】
（ｃ）式は、本発明の光拡散剤粒子の分散性を示す値であり、１〜２未満であることが好ましい。該粒子のβ（分散性）が、２以上程の凝集した粒子であると、光拡散性が低下するため、液晶パネル全体に輝度が行き渡り難い。従って、より好ましくは１〜１．８、更に好ましくは１〜１．５である。尚、電子顕微鏡（ＳＥＭ）観察写真からの平均直径の算出方法としては、座標読み取り装置（デジタイザーを用い、粒子の長径部分に当たる端から端までを線引きし、数値化作業を行う。核粒子の数値化作業は、サンプル数１０〜３０個で行い、平均直径を算出する。
【００２０】
本発明で使用できいるカルシウム系無機粒子としては、分散性や均一性に優れた粒子が得られる点で化学的に合成したものが好ましい。中でも、安定な光学物性を得るためには、例えば特開平７−１９６３１６号公報に記載の立方体状合成炭酸カルシウム粒子や特開２００２−３６３４４３号公報に記載の沈降製炭酸カルシウム、特開２０００−２０３８１５号公報に記載の合成リン酸カルシウム（ハイドロキシアパタイト）系粒子は、分散性や均一性、結晶安定性の面から特に好ましく用いることができる。
【００２１】
本発明に使用されるカルシウム系無機粒子は、粒子の分散性や安定性等を高めるため、表面処理剤を使用して表面を被覆処理することが可能である。
使用される表面処理剤としては、特に限定するものでないが、通常、水溶性界面活性剤や水溶性安定化剤、表面改質剤を用いることができる。
【００２２】
水溶性界面活性剤としては、例えば、ポリアクリル酸の塩（ナトリウム、カリウム、アンモニウム等）、アクリル酸−マレイン酸共重合体の塩（ナトリウム、カリウム、アンモニウム等）等のカルボン酸系重合物、トリポリリン酸ナトリウム、ヘキサメタリン酸ナトリウム等の縮合リン酸塩系無機物、その他、上記以外の一般的なアニオン系界面活性剤、カチオン系界面活性剤、非イオン性活性剤等使用できる。
【００２３】
水溶性安定剤としては、カルボキシメチルセルロース（ＣＭＣ）、ヒドロキシエチルセルロース（ＨＥＣ）、メチルセルロース（ＭＣ）、ヒドロキシプロピルセルロース（ＨＰＣ）、ゼラチン、プルラン、アルギン酸、ペクチン等の天然系・半合成水溶性高分子系、ポリビニルアルコール、アクリル酸系ポリマー、エチレンイミン系ポリマー、ポリエチレンオキシド、ポリアクリルアミド、ポリスチレンスルホン酸塩、ポリアミジン、イソプレン系スルホン酸ポリマー等の合成系水溶性高分子等が例示できる。
【００２４】
表面改質剤としては、シランカップリング剤やチタネートカップリング剤等のカップリング剤、トリメチルフォスフェート（ＴＭＰ）、トリエチルフォスフェート（ＴＥＰ）に代表される有機リン酸エステル及びアクリル酸、メタクリル酸、シュウ酸、クエン酸等の他の有機酸。カプリル酸、ラウリン酸、ミリスチン酸、パルミチン酸、ステアリン酸に代表される飽和脂肪酸及びその塩（ナトリウム、カリウム）、オレイン酸、エライジン酸、リノール酸、リシノール酸に代表される不飽和脂肪酸及びその塩（ナトリウム、カリウム）、繊維素化合物、シロキサン化合物等が例示できる。
【００２５】
上記表面処理剤は、それぞれ単独又は必要に応じ、２種以上組み合わせて使用される。これらの表面処理剤のうちで、特にポリアクリル酸塩（ナトリウム、カリウム等のアルカリ金属塩）、ヘキサメタリン酸ナトリウム、有機リン酸エステルは、透明樹脂フィルムとの相溶性や安定性の面で相性が良好である。
【００２６】
表面処理量に関しては、粒子のＢＥＴ比表面積によって左右されるため、特に限定されるのもではないが、通常０．１〜３０重量％である。表面処理量が０．１重量％未満の場合、粒子が小さいと乾燥・粉末化の際、未処理面同士で２次凝集を形成するため分散不良の原因となりやすい。また３０重量％を超えると、表面処理剤過多による表面処理剤の遊離が起きやすい。
【００２７】
以上のように、本発明の光拡散剤は、分散性や安定性が高く、光拡散用透明樹脂フィルムに優れた光学物性を付与することができる。もちろん、必要に応じて各種機能性粒子あるいは各種添加剤を併用したり、加工を施すことは何ら差し支えない。機能性粒子としては例えば、ガラス、シリカ、硫酸バリウム、酸化チタン、硫酸マグネシウム、炭酸マグネシウム、炭酸カルシウム、リン酸カルシウム等の無機粒子、またはアクリル樹脂、有機シリコーン樹脂、ポリスチレン樹脂、尿素樹脂、ホルムアルデヒド縮合物、フッ素樹脂等の有機架橋樹脂などが挙げられる。添加剤としては例えば、顔料、染料、蛍光増白剤、酸化防止剤、耐熱剤、耐光剤、耐候剤、耐電防止剤、離剥剤、相溶化剤などを挙げることができる。また加工とは、例えばエンボス加工を施して微細な凹凸を形成することなどが挙げられる。
【００２８】
本発明の光拡散性樹脂フィルムに適用できる樹脂の種類としては、透明熱可塑性樹脂であれば特に限定されるものでなく、例えば、ポリエチレンテレフタレート、ポリエチレン−２，６−ナフタレート、ポリプロピレンテレフタレート、ポリブチレンテレフタレート等のポリエステル系樹脂、ポリカーボネート、ポリスチレン、ポリエチレン、ポリプロピレン、ポリメチルペンテン等のポリオレフィン系樹脂、ポリアミド、ポリエーテル、ポリエステルアミド、ポリエーテルエステル、ポリ塩化ビニル、ポリ（メタ）アクリル酸エステル及びこれらを主たる成分とする共重合体、またはこれら樹脂の混合物等が挙げられる。耐熱性や耐水性の観点から、ポリエステル系樹脂が好ましい。
【００２９】
前記した光拡散性樹脂フィルムに配合される本発明の光拡散剤の添加量は、樹脂フィルム１００重量部に対し５〜３０重量部が適当で、特に８〜２０重量部が好ましい。５重量部未満では、添加量が少なく光拡散性が不十分であると共に、合成樹脂に配合して均一に分散させる精度が低下する。他方、３０重量部を越えると、フィルム強度や透明性を低下させ、液晶表示の高輝度化に悪影響を及ぼしやすく好ましくない。
また、透明樹脂のフィルム化は常法である２軸延伸法にて製膜することが適当である。延伸倍率においては、特に制限されないが、通常、縦方向に２〜４倍程度、横方向に２〜５倍程度に延伸するのが適当である。
【００３０】
本発明の光拡散剤を透明樹脂フィルム中に含有させる方法については、混練機を用いて樹脂中に練り込む方法が好ましいが、例えばポリエステル系樹脂の場合、本発明の光拡散剤をポリエステルの原料となるエチレングリコール中に懸濁化させ、重縮合反応時に添加する方法や、本発明の光拡散剤を水溶媒もしくはトルエン／メチルエチルケトン等の非水溶媒に懸濁化し、透明樹脂フィルムにコーティングする方法も特に問題なく適用することができる。
【００３１】
【実施例】
以下、本発明を実施例及び比較例に基づいて更に詳細に説明するが、本発明はこれらにより何ら制限されるものではない。
【００３２】
実施例１
特開平７−１９６３１６号公報の実施例３の方法で、立方体状の合成炭酸カルシウムを作製した。
即ち、１．４０モル／１リッターの濃度の炭酸ナトリウム溶液（炭酸イオン溶液）、１．４０モル／１リッターの濃度の塩化カルシウム溶液（カルシウムイオン溶液）、及び０．０４５モル／１リッターの水酸化ナトリウム溶液（反応緩衝剤）を各々１００リッター調製した。
該水酸化ナトリウム溶液と炭酸ナトリウム溶液を混合し混合液を調製し、該混合液と塩化ナトリウム溶液の液温を共に１７．０℃に調製した。
次に塩化ナトリウム溶液１００リッターを水酸化ナトリウム溶液と炭酸ナトリウム溶液の混合液２００リッターに滴下し、撹拌条件下炭酸化反応を行い、滴下開始２７０秒後に滴下供給を終了した。滴下終了１８０秒後、反応系内に存在する炭酸カルシウム理論生成量の０．８重量％相当量のヘキサメタ燐酸ナトリウムを添加し、さらに５分間撹拌した。
以上のようにして調製された炭酸カルシウムの水懸濁液を遠心脱水機を用いて濃縮し、濃縮液に水を加え希釈し撹拌後、再度希釈液を遠心脱水機を用いて濃縮した。得られた炭酸カルシウムの３重量％の水懸濁液のアンモニウムイオン及びアルカリ金属イオンの総和を測定したところ８ｐｐｍであり、その電気電導度を測定したところ３０μＳ／ｃｍであった。
得られた炭酸カルシウムを電子顕微鏡で観察した結果、その形状は頂点及びエッジ部分に丸みを有する立方体状の炭酸カルシウムであった。
また、Ｘ線回折により観察した結果、得られた炭酸カルシウムの結晶型は、ほぼカルサイトであることが確認された。
得られた平均粒子径０．５μｍの合成炭酸カルシウム粉体１００重量部とトリメチルフォスフェート（ＴＭＰ）２重量部をヘンシェルミキサーにて１２０℃に達するまで混合し、光拡散剤を作製した。得られた各物性を表１に示す。
【００３３】
実施例２
特開平７−１９６３１６号公報の実施例１の方法で、立方体状の合成炭酸カルシウムを作製した。
即ち、上記した合成方法において、炭酸カルシウム溶液の濃度を１．００モル／１リッター、塩化カルシウム溶液の濃度を１．００モル／１リッター、水酸化ナトリウム溶液の濃度を０．０３モル／１リッター、ヘキサメタ燐酸ナトリウムの添加量を０．４重量％相当量に変更した他は同様に操作した。
即ち、平均粒子径１．３μｍの合成炭酸カルシウム粉体１００重量部とステアリン酸１．５重量部をヘンシェルミキサーにて１２０℃に達するまで混合し、光拡散剤を作製した。得られた各物性を表１に示す。
【００３４】
実施例３
特開２００２−３６３４４３の実施例１の方法で、沈降製炭酸カルシウムの水懸濁液を作製した。
即ち、ＢＥＴ比表面積１４ｍ２／ｇの沈降製炭酸カルシウムを１０重量％含有する水懸濁液を用意し、このスラリーの温度を８０℃に調整しながら１０分間攪拌して、沈降製炭酸カルシウムの水懸濁液を作成した。得られた平均粒子径０．５μｍの沈降製炭酸カルシウムを１０重量％含有する水懸濁液を、該懸濁液の温度を８０℃に調整しながら１０分間撹拌後、下記に示した界面活性剤Ａとヘキサメタリン酸ソーダ（試薬１級）を炭酸カルシウム固形分に対してそれぞれ、２．９重量％と０．６重量％添加し、３０分間撹拌した後、脱水・乾燥・解砕して、１００重量部を光拡散材として用いた。各物性を表１に示す。
【００３５】
＜界面活性剤Ａの組成＞
ステアリン酸カリウム ６０重量％
オレイン酸ナトリウム ８重量％
パルチミン酸ナトリウム ２０重量％
ミリスチン酸ナトリウム ２重量％
ラウリン酸ナトリウム １０重量％
【００３６】
実施例４
特開２０００−２０３８１５の実施例１の方法で、ハイドロキシアパタイトを作製した。
即ち、下記の担体（Ｍ）の調製条件に従い、邪魔板付きで、直径０．６ｍのタービン羽根１枚の撹拌機付きの０．４ｍ３ ステンレスタンクに濃度を調整し温調した炭酸カルシウムの水懸濁液分散体を投入し、撹拌下に燐酸の希釈水溶液を滴下混合し、熟成条件に従い攪拌を行いながら熟成し、多孔質リン酸カルシウム系物質からなる担体（Ｍ）を調製した。
次に、熟成終了後、下記の複合体（ＭＲ）の調製条件に従い、撹拌しながら炭酸カルシウム水懸濁液及び水溶性リン酸塩水溶液を別々に滴下混合し、熟成条件に従い撹拌を行いながら熟成し、担体（Ｍ）にリン酸カルシウム系化合物（Ｒ）を担持させた複合体（ＭＲ）を調製した。
【００３７】
「担体（Ｍ）の調製条件」
炭酸カルシウムの平均径（μｍ） ０．１
調製後の炭酸カルシウムの水懸濁液分散体の固形分濃度（重量部＊） １０
リン酸の希釈水溶液の固形分濃度（重量部＊） １０
（混合）
Ｃａ／ｐ １．９５
滴下時間（分） ３００
反応温度（℃） ５０
水懸濁液ｐＨ ６−７
攪拌羽根周速（ｍ／秒） ５
（熟成）
時間（分） １０００
水懸濁液ｐＨ ７−８
【００３８】
「複合体（ＭＲ）の調製条件」
担体（Ｍ）の水懸濁液（ｋｇ） １００
固形分濃度（重量部 ＊） ５
炭酸カルシウムの平均径（μｍ） ０．１
水懸濁液固形分濃度（重量部 ＊） １０
使用するリン酸源 リン酸一ナトリウム
希釈水溶液の固形分濃度（重量部 ＊） ２０
（混合）
Ｃａ／Ｐの原子比 １．６７
反応温度（℃） ７０
リン酸カルシウム系化合物（Ｒ）の担持量（重量部 ＊＊） ３００
滴下時間（分：１００ 重量部当たり） ６０
攪拌羽根周速（ｍ／秒） ５
水懸濁液ｐＨ ８−１０
（熟成）
時間（分） １０００
水懸濁液温度（℃） ７０
水懸濁液ｐＨ ９−１０
攪拌羽根周速（ｍ／秒） ５
＊ 水１００重量部当りの重量部
＊＊ 担体（Ｍ）１００重量部当りの重量部
得られた平均粒子径０．８μｍのハイドロキシアパタイト粉体１００重量部とＴＭＰ２重量部をヘンシェルミキサーにて１２０℃に達するまで混合し、光拡散剤を作製した。得られた各物性を表１に示す。
【００３９】
比較例１
天然炭酸カルシウムを粉砕・分級して得た平均径１．０μｍの重質炭酸カルシウム粉体１００重量部とステアリン酸１．５重量部をヘンシェルミキサーにて１２０℃に達するまで混合し、光拡散剤を作製した。得られた各物性を表１に示す。
【００４０】
比較例２
平均粒子径１．６μｍの硫酸バリウム粉体（ＡＤ硫酸バリウム、日本化学工業社製）１００重量部とＴＭＰ１．５重量部をヘンシェルミキサーにて１２０℃に達するまで混合し、光拡散剤を作製した。得られた各物性を表１に示す。
【００４１】
【表１】
実施例５〜８、比較例３、４
粘度０．６４ｄｌ／ｇのＰＥＴ粉体を１７０℃で十分に真空乾燥した後、下記の配合比でプラネタリーミキサーで１分間混合した。混合物を２８０℃の押出機に供給し、Ｔ型ダイより溶融押出して、表面温度４０℃の金属ドラムに巻き付け冷却固化せしめ、未延伸フィルムを作製した。さらに、フィルムを延伸温度９０℃にて縦横３．５倍に２軸延伸し、厚さ１００μｍの光拡散性樹脂フィルムを得た。
（配合）
ＰＥＴ １００重量部
実施例１〜４・比較例１〜２の各光拡散剤 １０重量部
蛍光増白剤 ０．０３重量部
【００４３】
参考例
前記、実施例及び比較例の粒子を除いて下記配合比とした他は、同様の方法で厚さ１００μｍの基剤フィルムを得た。
（配合）
ＰＥＴ １００重量部
蛍光増白剤 ０．０３重量部
光拡散剤として、アクリル樹脂（テクポリマーＭＢＸ−２０、積水化成工業社製）を下記の配合比で懸濁化後、基剤フィルムの片面に該懸濁液をコンマダイレクト法によりコーティングし、１２０℃で１分間熱風乾燥させ、光拡散層４０μｍを形成した光拡散性樹脂フィルムを得た。
【００４４】
実施例５〜８、比較例３〜４及び参考例で得られた光拡散性樹脂フィルムの全光線透過率や光拡散性（ヘイズ）は、積分球式光線透過率測定装置（ＨＧＭ−２ＤＰ、スガ試験器社製）により測定した。
また輝度は、図１に示すように、１３．３インチの直管一灯サイドライト型バックライトの導光板上に、得られた光拡散性樹脂フィルムを置き、正面輝度（ＬＳ−１１０、ミノルタカメラ社製）を測定した。
尚、動光板のみの正面輝度は、１５００（カンデラ／ｍ２）であった。評価結果を表２に示す。
【００４５】
【表２】
表１、２より、実施例に代表される合成カルシウム系無機粒子からなる光拡散剤は粒子の分散性や均一性が良好で、全光線透過率や光拡散率共に高く、粒子が小さい程、参考例に比べて同等の正面輝度が向上することが確認できた。一方、粒子の分散性や均一性が悪い天然の炭酸カルシウム（比較例３）や光学特性に偏りがある硫酸バリウム（比較例４）は、正面輝度が不足し、練り込み法で対応することができないことが確認された。
【００４７】
【発明の効果】
叙上のとおり、本発明の合成樹脂フィルム用拡散剤は、練り込み法により、コーティング法と同等の光学特性を備えた光拡散性樹脂フィルムを提供することができる。
【図面の簡単な説明】
【図１】実施例及び比較例で用いたサイドライト型面光源装置を示す概略図である。
【符号の説明】
１ リフレクター
２ 導光体
３ 光反射フィルム
４ 光拡散性樹脂フィルム
５ 光源[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a light-diffusing agent for a synthetic resin film and a light-diffusing resin film using the same, and more particularly, to a light suitable for a light-diffusing resin film used for a backlight of a liquid crystal display, a lighting device and the like. The present invention relates to a diffusing agent and a light diffusing resin film using the light diffusing agent.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a display device used for a liquid crystal display such as a personal computer or a television displays a liquid crystal using a backlight from behind a liquid crystal panel. The backlight system can be roughly classified into two types: a direct type in which a light source is disposed directly below a liquid crystal panel, and a sidelight type in which a light source is disposed at an end of the liquid crystal panel. The former direct type is used for applications requiring high luminance such as a television monitor, and the sidelight type is used for a thin notebook personal computer or an application requiring low power consumption. In particular, with regard to the latter sidelight type, thinning and low power consumption are possible, and the size of liquid crystal displays is increasing, and high brightness near the direct type is being studied in various fields. Improvement of the light diffusion film (see FIGS. 1 and 2), which is one of the important members in increasing the brightness, is an essential element.
[0003]
As a function of the light diffusion film, a transparent resin film containing particles for improving light transmittance and light diffusion and improving front luminance and viewing angle is required. As a method for producing the light diffusion film, an inorganic compound such as barium sulfate, titanium oxide, or calcium carbonate was used for a transparent resin film in the old days, but barium sulfate or titanium oxide is more diffusible than light transmittance. In addition, calcium carbonate is obtained by crushing and classifying natural heavy calcium carbonate, so that the uniformity and dispersibility of the particles are low, and it is not possible to sufficiently cope with high image quality of liquid crystals (for example, see Patent Document 1). 1, 2). Therefore, at present, the case where a spherical polymer bead is used and the lens effect function of the bead is used is mainly used.
[0004]
[Patent Document 1]
JP-A-3-78701 [Patent Document 2]
JP-A-6-155677
However, polymer beads are inferior to inorganic particles in heat resistance, chemical resistance, etc., so it is difficult to knead them into the resin using a kneader in terms of shape stability, etc. (Bead coating) method. However, in the case of the coating method, there are problems that the process is twice as much as it is post-processing, and that the yield is extremely poor and the running cost is extremely high. In addition, since the film thickness tends to be uneven even in the physical properties, the optical characteristics tend to be non-uniform, and for example, there is a problem that it is difficult to cope with a thinner resin film.
[0006]
[Problems to be solved by the invention]
The present invention has been made in view of such circumstances, and has a light diffusion property and high light transmittance comparable to that of polymer beads, and can be used with a resin by using a conventional kneading apparatus without newly installing a coating apparatus. An object of the present invention is to provide a light diffusing agent for a synthetic resin film, which can be compounded and is made of inorganic particles which can be produced at low cost.
[0007]
[Means for Solving the Problems]
The present inventors have conducted intensive studies to achieve the above object, and as a result, have found that the above-mentioned problems are solved by using calcium-based inorganic particles having a specific particle size, and have completed the present invention.
[0008]
That is, the invention according to claim 1 of the present invention includes a light diffusing agent for a synthetic resin film, comprising a calcium-based inorganic compound satisfying the following formulas (a) and (b). is there.
(A) 0.1 ≦ d50 ≦ 5 (μm)
(B) 0 ≦ α <2
However,
d50: 50% by weight of cumulative weight average particle diameter (μm 2) calculated from the larger particle side in the particle size distribution by laser diffraction (Microtrack FRA)
α: Uniformity of calcium-based inorganic particles, represented by α = (d90−d10) / d50.
d90: 90% by weight cumulative average particle diameter (μm 2) calculated from the larger particle side in the particle size distribution by laser diffraction (Microtrack FRA)
d10: In the particle size distribution in the laser diffraction method (Microtrack FRA), the total weight of 10% by weight calculated from the larger particle side, the average particle diameter (μm).
[0009]
The invention according to claim 2 of the present invention is the light diffusing agent for a synthetic resin film according to claim 1, further satisfying the following formula (c).
(C) 1 ≦ β <2
However,
β: Shows the dispersibility of calcium-based inorganic particles, and is represented by β = d50 / Dsem50.
Dsem50: average diameter of calcium-based inorganic particles observed with an electron microscope (SEM)
The invention according to
[0011]
The invention according to claim 4 of the present invention is characterized in that the calcium-based inorganic particles are at least one kind selected from a carboxylic acid-based polymer, a condensed phosphoric-acid-based inorganic substance, an organic phosphate-based compound, and a saturated / unsaturated fatty acid-based compound. The light diffusing agent for a synthetic resin film according to claim 1, wherein the light diffusing agent is coated with a surface treatment agent.
[0012]
The invention according to
[0013]
[Embodiment of the present invention]
Hereinafter, the present invention will be described in detail.
The calcium-based inorganic particles constituting the light diffusing agent for a synthetic resin film of the present invention are not particularly limited as long as they are hardly soluble calcium-based inorganic particles. For example, calcium carbonate, calcium phosphate, calcium sulfate, calcium silicate, calcium hydroxide And calcium-based hydrotalcite. Among them, calcium carbonate (calcite) and calcium phosphate (hydroxyapatite) have high crystal stability, and the refractive index of light is close to that of resin, so that they have good compatibility with the resin film in transparency and light transmission. Excellent in efficiency and light diffusion. On the other hand, inorganic particles such as titanium oxide, zinc oxide, alumina, and barium sulfate have too high absorptivity and light diffusivity, so that it is difficult to obtain the optical properties required in the present invention.
[0014]
Further, the calcium-based inorganic particles need to satisfy the following expressions (a) and (b).
(A) 0.1 ≦ d50 ≦ 5 (μm)
(B) 0 ≦ α <2
However,
d50: 50% by weight of cumulative weight average particle diameter (μm 2) calculated from the larger particle side in the particle size distribution by laser diffraction (Microtrack FRA)
α: Uniformity of calcium-based inorganic particles, represented by α = (d90−d10) / d50.
d90: 90% by weight cumulative average particle diameter (μm 2) calculated from the larger particle side in the particle size distribution by laser diffraction (Microtrack FRA)
d10: In the particle size distribution in the laser diffraction method (Microtrack FRA), the total weight of 10% by weight calculated from the larger particle side, the average particle diameter (μm).
[0015]
Formula (a) requires that the calcium-based inorganic particles of the present invention have an average particle diameter (d50) measured by a particle size distribution analyzer of 0.1 to 5 μm. If it is less than 0.1 μm, the dispersibility of the particles is extremely reduced due to the influence of intermolecular force and the like, so that stable light diffusion cannot be obtained. If it exceeds 5 μm, it is necessary to increase the amount of addition in order to obtain desired optical properties. However, if the amount is increased, unevenness on the surface of the resin film becomes conspicuous and causes uneven light scattering. Therefore, it is preferably 0.3 to 3 μm, more preferably 0.5 to 2 μm.
[0016]
The expression (b) is a value indicating the uniformity of the calcium inorganic particles of the present invention, and needs to be 0 to less than 2. If the α (uniformity) of the particles is non-uniform so as to exceed the upper limit, uniform optical properties cannot be obtained, and the high brightness, which is the object of the present invention, cannot be achieved. Therefore, it is preferably 0 to 1.5, and more preferably 0 to 1.
[0017]
The particle size distribution measurement conditions calculated by the formulas (a) and (b) are shown below.
A calcium carbonate sample and water weighed in a 140 ml mayonnaise bottle as described below are measured by a laser diffraction particle size distribution analyzer (FRA: manufactured by Microtrolak).
The ultrasonic dispersion used as the preliminary dispersion is preferably performed under a certain condition. The ultrasonic disperser used in the present invention uses US-300T (manufactured by Nippon Seiki Seisakusho) under the current value of 300 μA for 60 seconds. Is preliminarily dispersed under the given conditions.
(Blending of suspension for particle size measurement)
(I) 5 g of calcium-based inorganic particles
(II) 50 g of methanol
[0018]
The light diffusing agent of the present invention preferably satisfies the following formula (c) in addition to the above formulas (a) and (b).
(C) 1 ≦ β <2
However,
β: Shows the dispersibility of calcium-based inorganic particles, and is represented by β = d50 / Dsem50.
Dsem50: Average particle diameter of calcium-based inorganic particles observed with an electron microscope (SEM).
[0019]
Formula (c) is a value indicating the dispersibility of the light diffusing agent particles of the present invention, and is preferably less than 1-2. When β (dispersibility) of the particles is about 2 or more, the light diffusibility is reduced, and thus it is difficult to spread the luminance over the entire liquid crystal panel. Therefore, it is more preferably 1 to 1.8, and still more preferably 1 to 1.5. In addition, as a method of calculating the average diameter from a photograph observed with an electron microscope (SEM), a coordinate reading device (digitizer is used to draw a line from end to end corresponding to the long diameter portion of the particle, and a numerical operation is performed. The conversion operation is performed with 10 to 30 samples, and the average diameter is calculated.
[0020]
The calcium-based inorganic particles that can be used in the present invention are preferably chemically synthesized in that particles having excellent dispersibility and uniformity can be obtained. Among them, in order to obtain stable optical properties, for example, cubic synthetic calcium carbonate particles described in JP-A-7-196316, precipitated calcium carbonate described in JP-A-2002-363443, JP-A-2000-203815 The synthetic calcium phosphate (hydroxyapatite) -based particles described in Japanese Patent Application Laid-Open Publication No. H11-146,078 can be particularly preferably used in terms of dispersibility, uniformity, and crystal stability.
[0021]
The surface of the calcium-based inorganic particles used in the present invention can be coated with a surface treating agent to enhance the dispersibility and stability of the particles.
The surface treatment agent to be used is not particularly limited, but usually, a water-soluble surfactant, a water-soluble stabilizer, and a surface modifier can be used.
[0022]
Examples of the water-soluble surfactant include carboxylic acid-based polymers such as salts of polyacrylic acid (sodium, potassium, ammonium, etc.), salts of acrylic acid-maleic acid copolymer (sodium, potassium, ammonium, etc.), Condensed phosphate-based inorganic substances such as sodium tripolyphosphate and sodium hexametaphosphate, and other common anionic surfactants, cationic surfactants, and nonionic surfactants other than those described above can be used.
[0023]
Examples of water-soluble stabilizers include carboxymethylcellulose (CMC), hydroxyethylcellulose (HEC), methylcellulose (MC), hydroxypropylcellulose (HPC), gelatin, pullulan, alginic acid, pectin, etc. And synthetic water-soluble polymers such as polyvinyl alcohol, acrylic acid polymer, ethyleneimine polymer, polyethylene oxide, polyacrylamide, polystyrene sulfonate, polyamidine, and isoprene sulfonic acid polymer.
[0024]
Examples of the surface modifier include coupling agents such as a silane coupling agent and a titanate coupling agent, organic phosphates represented by trimethyl phosphate (TMP) and triethyl phosphate (TEP), acrylic acid, methacrylic acid, Other organic acids such as oxalic acid and citric acid. Saturated fatty acids and their salts (sodium and potassium) represented by caprylic acid, lauric acid, myristic acid, palmitic acid and stearic acid, and unsaturated fatty acids and salts thereof represented by oleic acid, elaidic acid, linoleic acid and ricinoleic acid (Sodium, potassium), cellulose compounds, siloxane compounds and the like.
[0025]
The above surface treatment agents are used alone or in combination of two or more as needed. Among these surface treatment agents, polyacrylates (alkali metal salts such as sodium and potassium), sodium hexametaphosphate, and organic phosphates are particularly compatible with the transparent resin film in terms of compatibility and stability. Good.
[0026]
The surface treatment amount is not particularly limited because it depends on the BET specific surface area of the particles, but is usually 0.1 to 30% by weight. When the surface treatment amount is less than 0.1% by weight, if the particles are small, secondary aggregation is formed between the untreated surfaces during drying and pulverization, which tends to cause poor dispersion. If it exceeds 30% by weight, release of the surface treatment agent due to excessive surface treatment agent is likely to occur.
[0027]
As described above, the light diffusing agent of the present invention has high dispersibility and stability, and can impart excellent optical properties to the transparent resin film for light diffusion. Of course, if necessary, various functional particles or various additives may be used in combination or processed. As the functional particles, for example, glass, silica, barium sulfate, titanium oxide, magnesium sulfate, magnesium carbonate, calcium carbonate, inorganic particles such as calcium phosphate, or acrylic resin, organic silicone resin, polystyrene resin, urea resin, formaldehyde condensate, Organic cross-linking resins such as fluororesins may be used. Examples of the additives include pigments, dyes, optical brighteners, antioxidants, heat-resistant agents, light-proofing agents, weathering agents, antistatic agents, exfoliating agents, compatibilizers, and the like. Processing includes, for example, embossing to form fine irregularities.
[0028]
The type of resin applicable to the light diffusing resin film of the present invention is not particularly limited as long as it is a transparent thermoplastic resin. For example, polyethylene terephthalate, polyethylene-2,6-naphthalate, polypropylene terephthalate, polybutylene Polyester resins such as terephthalate; polyolefin resins such as polycarbonate, polystyrene, polyethylene, polypropylene and polymethylpentene; polyamides, polyethers, polyesteramides, polyetheresters, polyvinyl chloride, poly (meth) acrylates and the like. Examples thereof include a copolymer as a main component, a mixture of these resins, and the like. From the viewpoint of heat resistance and water resistance, polyester resins are preferred.
[0029]
The amount of the light diffusing agent of the present invention to be added to the light diffusing resin film is suitably 5 to 30 parts by weight, particularly preferably 8 to 20 parts by weight, per 100 parts by weight of the resin film. If the amount is less than 5 parts by weight, the amount of addition is small and the light diffusibility is insufficient, and the accuracy of blending with the synthetic resin to uniformly disperse it is reduced. On the other hand, when the amount exceeds 30 parts by weight, the film strength and the transparency are lowered, and it is not preferable because the brightness of the liquid crystal display is adversely affected.
It is appropriate that the transparent resin is formed into a film by a conventional biaxial stretching method. Although there is no particular limitation on the stretching ratio, it is usually appropriate to stretch the film about 2 to 4 times in the vertical direction and about 2 to 5 times in the horizontal direction.
[0030]
The method of incorporating the light diffusing agent of the present invention into a transparent resin film is preferably a method of kneading the resin with a kneading machine.For example, in the case of a polyester resin, the light diffusing agent of the present invention is a raw material of polyester. A method in which the light diffusing agent of the present invention is suspended in an aqueous solvent or a non-aqueous solvent such as toluene / methyl ethyl ketone and coated on a transparent resin film. Can be applied without any particular problem.
[0031]
【Example】
Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.
[0032]
Example 1
Cubic synthetic calcium carbonate was prepared by the method of Example 3 of JP-A-7-196316.
That is, a sodium carbonate solution (carbonate solution) having a concentration of 1.40 mol / 1 liter, a calcium chloride solution (calcium ion solution) having a concentration of 1.40 mol / 1 liter, and water having a concentration of 0.045 mol / 1 liter 100 liters of sodium oxide solution (reaction buffer) was prepared for each.
The sodium hydroxide solution and the sodium carbonate solution were mixed to prepare a mixed solution, and the temperature of the mixed solution and the sodium chloride solution were both adjusted to 17.0 ° C.
Next, 100 liters of a sodium chloride solution was dropped into 200 liters of a mixed solution of a sodium hydroxide solution and a sodium carbonate solution, a carbonation reaction was performed under stirring, and the dropping supply was terminated 270 seconds after the start of the dropping. After 180 seconds from the completion of the dropwise addition, sodium hexametaphosphate equivalent to 0.8% by weight of the theoretical amount of calcium carbonate present in the reaction system was added, and the mixture was further stirred for 5 minutes.
The aqueous suspension of calcium carbonate prepared as described above was concentrated using a centrifugal dehydrator, water was added to the concentrate to dilute and stir, and the diluent was again concentrated using a centrifugal dehydrator. The total amount of ammonium ions and alkali metal ions in a 3% by weight aqueous suspension of calcium carbonate obtained was 8 ppm, and its electric conductivity was 30 μS / cm.
Observation of the obtained calcium carbonate with an electron microscope revealed that the shape was cubic calcium carbonate having rounded vertices and edges.
Further, as a result of observation by X-ray diffraction, it was confirmed that the crystal form of the obtained calcium carbonate was almost calcite.
100 parts by weight of the obtained synthetic calcium carbonate powder having an average particle diameter of 0.5 μm and 2 parts by weight of trimethyl phosphate (TMP) were mixed with a Henschel mixer until the temperature reached 120 ° C. to prepare a light diffusing agent. Table 1 shows the obtained physical properties.
[0033]
Example 2
Cubic synthetic calcium carbonate was produced by the method of Example 1 in JP-A-7-196316.
That is, in the above synthesis method, the concentration of the calcium carbonate solution was 1.00 mol / 1 liter, the concentration of the calcium chloride solution was 1.00 mol / 1 liter, and the concentration of the sodium hydroxide solution was 0.03 mol / 1 liter. The same operation was performed except that the amount of sodium hexametaphosphate was changed to an amount equivalent to 0.4% by weight.
That is, 100 parts by weight of a synthetic calcium carbonate powder having an average particle diameter of 1.3 μm and 1.5 parts by weight of stearic acid were mixed with a Henschel mixer until the temperature reached 120 ° C. to prepare a light diffusing agent. Table 1 shows the obtained physical properties.
[0034]
Example 3
An aqueous suspension of precipitated calcium carbonate was prepared by the method of Example 1 of JP-A-2002-363443.
That is, an aqueous suspension containing 10% by weight of precipitated calcium carbonate having a BET specific surface area of 14 m 2 / g was prepared, and the slurry was stirred for 10 minutes while adjusting the temperature of the slurry to 80 ° C. A water suspension was made. The obtained aqueous suspension containing 10% by weight of precipitated calcium carbonate having an average particle diameter of 0.5 μm was stirred for 10 minutes while adjusting the temperature of the suspension to 80 ° C., and then the surface activity shown below was obtained. Agent A and sodium hexametaphosphate (reagent first grade) were added to 2.9% by weight and 0.6% by weight, respectively, based on the solid content of calcium carbonate, followed by stirring for 30 minutes, followed by dehydration, drying and crushing. 100 parts by weight were used as a light diffusing material. Table 1 shows the physical properties.
[0035]
<Composition of Surfactant A>
Potassium stearate 60% by weight
Sodium oleate 8% by weight
Sodium palmitate 20% by weight
Sodium myristate 2% by weight
Sodium laurate 10% by weight
[0036]
Example 4
Hydroxyapatite was produced by the method of Example 1 of JP-A-2000-203815.
That is, in accordance with the preparation conditions of the support below (M), with a baffle plate, water calcium carbonate temperature control was adjusted to a concentration of 0.4 m 3 stainless steel tank equipped with a turbine blade one agitator having a diameter of 0.6m The suspension dispersion was added, and a diluted aqueous solution of phosphoric acid was dropped and mixed with stirring, and the mixture was aged while stirring under aging conditions to prepare a carrier (M) composed of a porous calcium phosphate material.
Next, after the ripening is completed, the aqueous calcium carbonate suspension and the water-soluble phosphate aqueous solution are separately dropped and mixed under stirring according to the preparation conditions of the following complex (MR), and ripened while stirring under the aging conditions. Then, a composite (MR) in which the calcium phosphate compound (R) was supported on the carrier (M) was prepared.
[0037]
"Preparation conditions for carrier (M)"
Average diameter of calcium carbonate (μm) 0.1
Solid content concentration (weight part *) of the aqueous suspension dispersion of calcium carbonate after preparation 10
Solids concentration of diluted aqueous solution of phosphoric acid (parts by weight *) 10
(mixture)
Ca / p 1.95
Dropping time (min) 300
Reaction temperature (℃) 50
Water suspension pH 6-7
Stirrer blade peripheral speed (m / sec) 5
(Aging)
Time (minutes) 1000
Water suspension pH 7-8
[0038]
"Preparation conditions for composite (MR)"
Aqueous suspension of carrier (M) (kg) 100
Solids concentration (parts by weight *) 5
Average diameter of calcium carbonate (μm) 0.1
Water suspension solids concentration (parts by weight *) 10
Phosphoric acid source to be used Solid concentration of dilute aqueous sodium phosphate solution (parts by weight *) 20
(mixture)
Atomic ratio of Ca / P 1.67
Reaction temperature (° C) 70
Loading amount of calcium phosphate compound (R) (parts by weight **) 300
Dropping time (min: per 100 parts by weight) 60
Stirrer blade peripheral speed (m / sec) 5
Water suspension pH 8-10
(Aging)
Time (minutes) 1000
Water suspension temperature (℃) 70
Water suspension pH 9-10
Stirrer blade peripheral speed (m / sec) 5
* Parts by weight per 100 parts by weight of water ** parts by weight per 100 parts by weight of carrier (M) 100 parts by weight of obtained hydroxyapatite powder having an average particle diameter of 0.8 μm and 2 parts by weight of TMP at 120 ° C. using a Henschel mixer. To obtain a light diffusing agent. Table 1 shows the obtained physical properties.
[0039]
Comparative Example 1
100 parts by weight of heavy calcium carbonate powder having an average diameter of 1.0 μm obtained by pulverizing and classifying natural calcium carbonate and 1.5 parts by weight of stearic acid were mixed in a Henschel mixer until the temperature reached 120 ° C., and a light diffusing agent was used. Was prepared. Table 1 shows the obtained physical properties.
[0040]
Comparative Example 2
100 parts by weight of barium sulfate powder (barium sulfate AD, manufactured by Nippon Chemical Industry Co., Ltd.) having an average particle diameter of 1.6 μm and 1.5 parts by weight of TMP were mixed with a Henschel mixer until the temperature reached 120 ° C. to prepare a light diffusing agent. . Table 1 shows the obtained physical properties.
[0041]
[Table 1]
Examples 5 to 8, Comparative Examples 3 and 4
The PET powder having a viscosity of 0.64 dl / g was sufficiently vacuum-dried at 170 ° C., and then mixed for 1 minute with a planetary mixer at the following mixing ratio. The mixture was supplied to an extruder at 280 ° C., melt-extruded from a T-die, wound around a metal drum having a surface temperature of 40 ° C., cooled and solidified to prepare an unstretched film. Further, the film was biaxially stretched 3.5 times vertically and horizontally at a stretching temperature of 90 ° C. to obtain a light-diffusing resin film having a thickness of 100 μm.
(Combination)
100 parts by weight of PET 10 parts by weight of each light diffusing agent of Examples 1 to 4 and Comparative Examples 1 and 2 0.03 part by weight of optical brightener
Reference Example A base film having a thickness of 100 μm was obtained in the same manner except that the following compounding ratios were used except for the particles of the above Examples and Comparative Examples.
(Combination)
PET 100 parts by weight Fluorescent whitening agent 0.03 parts by weight An acrylic resin (Techpolymer MBX-20, manufactured by Sekisui Chemical Co., Ltd.) was suspended as a light diffusing agent at the following mixing ratio, and then applied to one surface of the base film. The suspension was coated by a comma direct method and dried with hot air at 120 ° C. for 1 minute to obtain a light diffusing resin film having a light diffusing layer of 40 μm.
[0044]
The total light transmittance and light diffusivity (haze) of the light-diffusing resin films obtained in Examples 5 to 8, Comparative Examples 3 and 4, and Reference Examples were measured using an integrating sphere-type light transmittance measuring device (HGM-2DP, Suga Test Instruments Co., Ltd.).
As shown in FIG. 1, the obtained light-diffusing resin film was placed on a light guide plate of a 13.3 inch straight-tube single-light sidelight-type backlight, and the front luminance (LS-110, Minolta Camera Co.) was measured.
The front luminance of only the moving plate was 1500 (candela / m 2 ). Table 2 shows the evaluation results.
[0045]
[Table 2]
From Tables 1 and 2, the light diffusing agent composed of the synthetic calcium-based inorganic particles represented by the examples has good dispersibility and uniformity of the particles, high both the total light transmittance and the light diffusivity, and the smaller the particles, It was confirmed that the front luminance was equivalent to that of the reference example. On the other hand, natural calcium carbonate (Comparative Example 3) having poor dispersibility and uniformity of particles and barium sulfate (Comparative Example 4) having a bias in optical characteristics have insufficient frontal luminance and can be handled by the kneading method. It was confirmed that it was not possible.
[0047]
【The invention's effect】
As described above, the diffusing agent for a synthetic resin film of the present invention can provide a light diffusing resin film having optical characteristics equivalent to those of a coating method by a kneading method.
[Brief description of the drawings]
FIG. 1 is a schematic view showing a sidelight type surface light source device used in Examples and Comparative Examples.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Reflector 2
Claims (5)
（ａ） ０．１≦ｄ５０≦５ （μｍ）
（ｂ） ０≦α＜２
但し、
ｄ５０：レーザー回折式（マイクロトラックＦＲＡ）における粒度分布において、大きな粒子側から起算した重量累計５０重量％平均粒子直径（μｍ ）
α ：カルシウム系無機粒子の均一性を示し、α＝（ｄ９０−ｄ１０）／ｄ５０で表される。
ｄ９０：レーザー回折式（マイクロトラックＦＲＡ）における粒度分布において、大きな粒子側から起算した重量累計９０重量％平均粒子直径（μｍ ）
ｄ１０：レーザー回折式（マイクロトラックＦＲＡ）における粒度分布において、大きな粒子側から起算した重量累計１０重量％平均粒子直径（μｍ ）A light diffusing agent for a synthetic resin film, comprising calcium-based inorganic particles satisfying the following formulas (a) and (b).
(A) 0.1 ≦ d50 ≦ 5 (μm)
(B) 0 ≦ α <2
However,
d50: 50% by weight of cumulative weight average particle diameter (μm 2) calculated from the larger particle side in the particle size distribution by laser diffraction (Microtrack FRA)
α: Uniformity of calcium-based inorganic particles, represented by α = (d90−d10) / d50.
d90: 90% by weight of cumulative weight average particle diameter (μm) calculated from the larger particle side in the particle size distribution in the laser diffraction method (Microtrack FRA)
d10: In a particle size distribution by a laser diffraction method (Microtrack FRA), a weight cumulative average 10% by weight average particle diameter (μm 2) calculated from a large particle side.
（ｃ） １≦β＜２
但し、
β ：カルシウム系無機粒子の分散性を示し、β＝ｄ５０／Ｄｓｅｍ５０で表される。
Ｄｓｅｍ５０：電子顕微鏡（ＳＥＭ）で観察した、カルシウム系無機粒子の平均粒子直径The light diffusing agent for a synthetic resin film according to claim 1, further satisfying the following formula (c).
(C) 1 ≦ β <2
However,
β: Shows the dispersibility of calcium-based inorganic particles, and is represented by β = d50 / Dsem50.
Dsem50: average particle diameter of calcium-based inorganic particles observed with an electron microscope (SEM)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2003061294A JP3981335B2 (en) | 2003-03-07 | 2003-03-07 | Light diffusing agent used for light diffusing synthetic resin film for backlight and light diffusing synthetic resin film for backlight using the light diffusing agent |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2003061294A JP3981335B2 (en) | 2003-03-07 | 2003-03-07 | Light diffusing agent used for light diffusing synthetic resin film for backlight and light diffusing synthetic resin film for backlight using the light diffusing agent |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2004269653A true JP2004269653A (en) | 2004-09-30 |
| JP3981335B2 JP3981335B2 (en) | 2007-09-26 |
Family
ID=33123551
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2003061294A Expired - Fee Related JP3981335B2 (en) | 2003-03-07 | 2003-03-07 | Light diffusing agent used for light diffusing synthetic resin film for backlight and light diffusing synthetic resin film for backlight using the light diffusing agent |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3981335B2 (en) |
Cited By (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006265472A (en) * | 2005-03-25 | 2006-10-05 | Maruo Calcium Co Ltd | Filler for light reflection porous film and light reflection porous film incorporated with the filler |
| JP2007119767A (en) * | 2005-09-30 | 2007-05-17 | Maruo Calcium Co Ltd | Additive for synthetic resin consisting heavy calcium carbonate and synthetic resin containing the same |
| CN100356247C (en) * | 2005-11-29 | 2007-12-19 | 长兴化学工业股份有限公司 | Optical thin sheet |
| JP2010241785A (en) * | 2009-03-19 | 2010-10-28 | Sekisui Plastics Co Ltd | Resin particle, method of manufacturing composite particle and cosmetic |
| KR101208339B1 (en) * | 2004-12-17 | 2012-12-05 | 마루오 칼슘 가부시키가이샤 | Filler for porous film and porous film wherein such filler is blended |
| WO2014058057A2 (en) * | 2012-10-12 | 2014-04-17 | 丸尾カルシウム株式会社 | Calcium carbonate filler for resin, and resin composition containing said filler |
| JP2015087420A (en) * | 2013-10-28 | 2015-05-07 | 帝人デュポンフィルム株式会社 | White polyester film |
| CN105572774A (en) * | 2014-10-13 | 2016-05-11 | 鸿富锦精密工业（深圳）有限公司 | Diffusion film, preparation method thereof, backlight module, display device and electronic device |
| CN105980310A (en) * | 2014-02-28 | 2016-09-28 | 丸尾钙株式会社 | Calcium carbonate filler for resin and resin composition including said filler |
| JP2018500413A (en) * | 2014-12-02 | 2018-01-11 | オムヤ インターナショナル アーゲー | Surface treatment dense material |
| CN108603651A (en) * | 2016-02-09 | 2018-09-28 | 纳诺科普有限公司 | Light guide with multiple light paths |
| CN109111701A (en) * | 2018-07-20 | 2019-01-01 | 台州市优天然生物材料股份有限公司 | A kind of composition preparing light guide plate |
| JP7442700B1 (en) | 2023-01-17 | 2024-03-04 | 株式会社ユポ・コーポレーション | Resin composition and resin sheet |
-
2003
- 2003-03-07 JP JP2003061294A patent/JP3981335B2/en not_active Expired - Fee Related
Cited By (19)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR101208339B1 (en) * | 2004-12-17 | 2012-12-05 | 마루오 칼슘 가부시키가이샤 | Filler for porous film and porous film wherein such filler is blended |
| JP2006265472A (en) * | 2005-03-25 | 2006-10-05 | Maruo Calcium Co Ltd | Filler for light reflection porous film and light reflection porous film incorporated with the filler |
| JP2007119767A (en) * | 2005-09-30 | 2007-05-17 | Maruo Calcium Co Ltd | Additive for synthetic resin consisting heavy calcium carbonate and synthetic resin containing the same |
| JP4494381B2 (en) * | 2005-09-30 | 2010-06-30 | 丸尾カルシウム株式会社 | Synthetic resin additive comprising heavy calcium carbonate and synthetic resin composition containing the same |
| CN100356247C (en) * | 2005-11-29 | 2007-12-19 | 长兴化学工业股份有限公司 | Optical thin sheet |
| JP2010241785A (en) * | 2009-03-19 | 2010-10-28 | Sekisui Plastics Co Ltd | Resin particle, method of manufacturing composite particle and cosmetic |
| CN104704036B (en) * | 2012-10-12 | 2017-05-31 | 丸尾钙株式会社 | Resin pearl filler and the resin combination containing the filler |
| WO2014058057A3 (en) * | 2012-10-12 | 2014-06-19 | 丸尾カルシウム株式会社 | Calcium carbonate filler for resin, and resin composition containing said filler |
| JPWO2014058057A1 (en) * | 2012-10-12 | 2016-09-05 | 丸尾カルシウム株式会社 | Calcium carbonate filler for resin and resin composition containing the filler |
| WO2014058057A2 (en) * | 2012-10-12 | 2014-04-17 | 丸尾カルシウム株式会社 | Calcium carbonate filler for resin, and resin composition containing said filler |
| US9815953B2 (en) | 2012-10-12 | 2017-11-14 | Maruo Calcium Co., Ltd. | Calcium carbonate filler for resin, and resin composition containing said filler |
| JP2015087420A (en) * | 2013-10-28 | 2015-05-07 | 帝人デュポンフィルム株式会社 | White polyester film |
| CN105980310A (en) * | 2014-02-28 | 2016-09-28 | 丸尾钙株式会社 | Calcium carbonate filler for resin and resin composition including said filler |
| CN105980310B (en) * | 2014-02-28 | 2018-11-06 | 丸尾钙株式会社 | Resin pearl filler and resin combination containing the filler |
| CN105572774A (en) * | 2014-10-13 | 2016-05-11 | 鸿富锦精密工业（深圳）有限公司 | Diffusion film, preparation method thereof, backlight module, display device and electronic device |
| JP2018500413A (en) * | 2014-12-02 | 2018-01-11 | オムヤ インターナショナル アーゲー | Surface treatment dense material |
| CN108603651A (en) * | 2016-02-09 | 2018-09-28 | 纳诺科普有限公司 | Light guide with multiple light paths |
| CN109111701A (en) * | 2018-07-20 | 2019-01-01 | 台州市优天然生物材料股份有限公司 | A kind of composition preparing light guide plate |
| JP7442700B1 (en) | 2023-01-17 | 2024-03-04 | 株式会社ユポ・コーポレーション | Resin composition and resin sheet |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3981335B2 (en) | 2007-09-26 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP3981335B2 (en) | Light diffusing agent used for light diffusing synthetic resin film for backlight and light diffusing synthetic resin film for backlight using the light diffusing agent | |
| KR101208339B1 (en) | Filler for porous film and porous film wherein such filler is blended | |
| CN101080453B (en) | Filler for porous film and porous film containing it | |
| JP4494381B2 (en) | Synthetic resin additive comprising heavy calcium carbonate and synthetic resin composition containing the same | |
| WO2017130946A1 (en) | Coated fine particles of alkaline-earth metal compound, dispersion in organic solvent, resin composition, and image display device | |
| CN108773141B (en) | Polyester reflecting film and preparation method and application thereof | |
| JP2009024068A (en) | Method for producing resin particles containing zirconium oxide nanoparticles and resin particles | |
| KR20010050120A (en) | Light scattering resin layer, color filter and liquid crystal display using the same | |
| WO2017029995A1 (en) | Optical film and image display device | |
| JP2006327187A (en) | Production process of reflection preventive laminate | |
| CN1474201A (en) | Optical element containing nano composite particles | |
| JP2006265472A (en) | Filler for light reflection porous film and light reflection porous film incorporated with the filler | |
| JP2005290054A (en) | Additive for synthetic resin consisting of heavy calcium carbonate and synthetic resin composition containing the same | |
| JP6631526B2 (en) | Highly dispersible alkaline earth metal compound fine powder, optical film, image display device, method for producing highly dispersible alkaline earth metal compound fine powder, fine powder dispersibility evaluation method, and fine powder dispersibility evaluation device | |
| JP2019043809A (en) | Aragonite-type precipitated calcium carbonate and its production method | |
| JP2001133607A (en) | Light scattering layer, light scattering plate, color filter and liquid crystal display device utilizing them | |
| JP4912609B2 (en) | Light diffusion plate resin composition and light diffusion plate | |
| JP3146139B2 (en) | Plastic additive for light diffusion and plastic composition for light diffusion | |
| JP2002258011A (en) | Light diffusion sheet and method of producing the same | |
| JPH07173331A (en) | Thermoplastic resin composition and its production | |
| CN101915948A (en) | Light-diffusing structure | |
| JP6533879B2 (en) | Light scattering sheet | |
| CN111433639B (en) | Particle mixture, method for improving light scattering properties using same, and light scattering member and optical device comprising same | |
| CN1877369A (en) | Method for producing an antireflective layered material | |
| JP2005055861A (en) | Optical member, light diffusing sheet, and reflector, light guide plate and prism sheet using optical member, and backlight unit using light diffusing sheet |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20060113 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20060815 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20060919 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20061116 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20070220 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20070423 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20070605 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20070629 |
|
| R150 | Certificate of patent or registration of utility model |
Ref document number: 3981335 Country of ref document: JP Free format text: JAPANESE INTERMEDIATE CODE: R150 Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20100706 Year of fee payment: 3 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20110706 Year of fee payment: 4 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20110706 Year of fee payment: 4 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120706 Year of fee payment: 5 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130706 Year of fee payment: 6 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| RD02 | Notification of acceptance of power of attorney |
Free format text: JAPANESE INTERMEDIATE CODE: R3D02 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| LAPS | Cancellation because of no payment of annual fees |