JPWO2003055950A1 - Coating composition and antistatic hard coat film - Google Patents

Abstract

Coating composition capable of continuously and uniformly forming a hard coat layer excellent in antistatic property, transparency, scratch resistance and chemical resistance, and antistatic hard having a hard coat layer formed by applying the composition A coated film is provided. Ultraviolet or radiation curable resin having at least three (meth) acryloyl groups that are cured by irradiation with ultraviolet rays or radiation, a conductive polymer, and one or two (meth) acryloyl groups and at least one hydroxyl group A coating composition that does not need to contain the compatibilizer when the ultraviolet or radiation curable resin has a hydroxyl group in its molecule, and a hard coating formed by applying this composition An antistatic hard coat film having a coating layer.

Description

（ｂ）ジトリメチロールプロパンテトラ（メタ）アクリレート（下式）、

（ｃ）ペンタエリスリトールテトラ（メタ）アクリレート（下式）、

（ｄ）ジペンタエリスリトールヘキサ（メタ）アクリレート（下式）

（ｅ）エチレンオキサイド変性リン酸トリ（メタ）アクリレート（下式）、

（ｆ）ペンタエリスリトールトリ（メタ）アクリレート（下式）

（ｇ）ジペンタエリスリトールモノヒドロキシペンタ（メタ）アクリレート（下式）

（ｈ）エピクロルヒドリン変性グリセロールトリ（メタ）アクリレート（下式）

（ｉ）エピクロルヒドリン変性トリメチロールプロパントリ（メタ）アクリレート（下式）

イソシアヌレート系として：
（ｊ）トリス（アクリロキシエチル）イソシアヌレート（下式）、

多価アルコールと多価カルボン酸及び／又はその無水物と（メタ）アクリル酸とをエステル化することによって得ることが出来るポリエステル（メタ）アクリレート、多価アルコール、多価イソシアネート及び水酸基含有（メタ）アクリレートを反応させることによって得られるポリウレタン（メタ）アクリレートが挙げられる。
上記（メタ）アクリロイル基を３個以上有する硬化型樹脂のうち、水酸基を持たない化合物を使用するときには、下記に示すような水酸基及び（メタ）アクリロイル基を有する化合物を必ず併用する必要がある。硬化型樹脂が３個以上の（メタ）アクリロイル基とともに、さらに水酸基も持つ場合は、これら化合物と導電性ポリマーのみで塗料とすることができる。その場合であっても、相溶化剤を併用することは相溶性という点で、塗料の安定化に好ましく、導電性ポリマーの凝集を防ぐことができる。
これらの化合物はいずれも紫外線又は放射線の照射により反応して３次元構造を作るので、ハードコート被膜の構造成分となる。したがって、その使用量は、塗料組成物の硬化時の固形分に対して５０〜８０重量％とすることが好ましい。紫外線で硬化反応を行うときには、光重合開始剤（以下「開始剤」という。）が必要であって、ベンゾフェノン系開始剤、ジケトン系開始剤、アセトフェノン系開始剤、ベンゾイン系開始剤、チオキサントン系開始剤、キノン系開始剤などのいかなる公知の開始剤を用いてもよい。通常開始剤は硬化型樹脂に対し、１〜１０重量％で用いられる。
一方、放射線で硬化反応を行うときは、開始剤は不要である。
本発明で用いる導電性ポリマーは、ハードコート層に帯電防止性能を付与する目的で用いられ、例えば、以下のような化合物が上げられる。
ポリエーテルとして、ポリアルキレンオキシド、ポリエーテルエステルアミド、アルキレンオキシド−エピハロヒドリン共重合体、メトキシポリアルキレングルコール（メタ）アクリレート共重合体などがを用いることができ、アルキレンとしては、エチレン、プロピレン、又はこれらの双方を含むものが好ましい。
４級アンモニウム塩基含有ポリマーとしては、４級アンモニウム塩基、好ましくは４級アンモニウム塩を含むポリマーであればいかなるものでもよい。４級アンモニウム塩とは、４級アンモニウムと酸やハロゲン等との塩であって、酸としては、主としてスルホン酸、塩酸などのハロゲン酸が好ましい。
４級アンモニウム塩基含有ポリマーについて代表的構造式（式中、ｌ、ｍ、ｎはそれぞれ適当な整数を表す。）と共に、以下に例示する。
（１）４級アンモニウム塩基含有（メタ）アクリレート共重合体（スチレン、アクリロニトリル、ブタジエン、塩化ビニルやこれらの混合物からなるポリマーの一部に４級アンモニウム塩基を持つ（メタ）アクリレートを共重合した化合物）

（２）４級アンモニウム塩基含有マレイミド共重合体（スチレン、アクリロニトリル、ブタジエンやこれらの混合物からなるポリマーの一部に４級アンモニウム塩基を持つマレイミドを共重合した化合物）

（３）４級アンモニウム塩基含有メタクリルイミド共重合体（アクリレート、メタクリレートとメタクリルイミドとの共重合体の一部に４級アンモニウム塩基を持つ化合物）

（４）４級アンモニウム塩基含有カルボベタイングラフト共重合体（ポリエチレンやポリプロピレンに４級アンモニウム塩が結合したカルボベタインがグラフト結合した化合物

スルホン酸含有ポリマーとしては、スルホン酸をスルホン酸塩の形で含有するポリマーが好ましく、例えば、ポリスチレンスルホン酸ソーダや、これとアクリロニトリル、ブタジエンやこれらの混合物との共重合体等が挙げられる。
これら導電性ポリマーの中で、ポリエーテル、４級アンモニウム塩基含有ポリマー、スルホン酸含有ポリマーが好ましく、４級アンモニウム塩基含有ポリマーがより好ましく、なかでも４級アンモニウム塩基含有（メタ）アクリレート共重合ポリマーは、導電性が高く、多種市販されており、ベースポリマーの種類も多種あり、硬化型樹脂と親和性の高いものを選択することが容易であるため特に好ましい。
導電性ポリマーの平均重量分子量は、ゲルパーミエーションクロマログラフィー（ＧＰＣ）を用いたポリスチレン標準により求められた、２×１０^４〜５０×１０^４が好ましく、より好ましくは２×１０^４〜３０×１０^４である。分子量が小さすぎる場合には、造膜性が低くてブロッキングを起こしやすく、分子量が大きすぎる場合には、硬化型樹脂との相溶性が悪く、不均一な塗料となると共に溶剤の揮散過程で凝集物が多発する。
導電性ポリマーの含有量は、ハードコート層用塗料の硬化時の固形分に対して１０〜４０重量％が好ましい。導電性ポリマーの含有量が少なすぎると、表面への水分子の吸着が十分に起こらず、帯電防止性能が発現しない。一方この含有量が多すぎると相対的に硬化型樹脂の割合が低下するためハードコート性（耐擦傷性）の低下が著しい。またこの範囲の量を使用することによりハードコート層に適度の柔軟性と耐衝撃性を付与し密着性を向上させることができる。
硬化型樹脂と導電性ポリマーは、極性の大きな違いから先に述べたように相溶性が悪く、これらを溶剤と共に塗料とし、フィルム上に塗布乾燥する過程で、導電性ポリマーが凝集して凝集物を作る。導電性ポリマー同士の凝集を防ぐため硬化型樹脂と相互に親和性を持たせる作用を持つものとして、水酸基と（メタ）アクリロイル基を持つ相溶化剤又はその相当物を併用する。
このような作用を持つ相溶化剤を以下に例示する。
構造式は全てアクリレートで示すが、（メタ）アクリレートも同様に使用できる。
（ａ）水酸基が１個、（メタ）アクリロイル基が１個の化合物：
２−ヒドロキシエチル（メタ）アクリレート（ＣＨ_２＝ＣＨＣＯＯＣＨ_２ＣＨ_２ＯＨ）、２−ヒドロキシプロピル（メタ）アクリレート（ＣＨ_２＝ＣＨＣＯＯＣＨ_２ＣＨＯＨＣＨ_３）、４−ヒドロキシブチル（メタ）アクリレート（ＣＨ_２＝ＣＨＣＯＯＣＨ_２ＣＨ_２ＣＨ_２ＣＨ_２ＯＨ）、２−ヒドロキシ−３−フェノキシプロピル（メタ）アクリレート（下式）

、エチレンオキサイド変性フタル酸（メタ）アクリレート（下式）

、ポリプロピレングリコール（メタ）アクリレート（ＣＨ_２＝ＣＨＣＯ（ＯＣＨ_２ＣＨＣＨ_３）_１２ＯＨ）、
（ｂ）水酸基が１個で、（メタ）アクリロイル基が２個の化合物：
グリセロールジ（メタ）アクリレート（ＣＨ_２＝ＣＨＣＯＯＣＨ_２ＣＨＯＨＣＨ_２ＯＣＯＣＨ＝ＣＨ_２）、エチレンオキサイド変性リン酸ジ（メタ）アクリレート（下式）

（ｃ）水酸基が２個で、（メタ）アクリロイル基が１個の化合物：
エチレンオキサイド変性リン酸（メタ）アクリレート（下式）

、グリセロール（メタ）アクリレート（ＣＨ_２＝ＣＨＣＯＯＣＨ_２ＣＨＯＨＣＨ_２ＯＨ）
（ｄ）水酸基が２個で、（メタ）アクリロイル基が２個の化合物：
エピクロルヒドリン変性１，６−ヘキサンジオールジ（メタ）アクリレート（ＣＨ_２＝ＣＨＣＯＯＣＨ_２ＣＨＯＨＣＨ_２Ｏ（ＣＨ_２）_６ＯＣＨ_２ＣＨＯＨＣＨ_２ＯＣＯＣＨ＝ＣＨ_２）、エピクロルヒドリン変性ジエチレングリコールジ（メタ）アクリレート（ＣＨ_２＝ＣＨＣＯＯＣＨ_２ＣＨＯＨＣＨ_２Ｏ（ＣＨ_２ＣＨ_２Ｏ）_２ＣＨ_２ＣＨＯＨＣＨ_２ＯＣＯＣＨ＝ＣＨ_２）、エピクロルヒドリン変性フタル酸ジ（メタ）アクリレート（下式）

、エピクロルヒドリン変性プロピレングリコールジ（メタ）アクリレート（ＣＨ_２＝ＣＨＣＯＯＣＨ_２ＣＨＯＨＣＨ_２ＯＣＨＣＨ_３ＣＨ_２ＯＣＨ_２ＣＨＯＨＣＨ_２ＯＣＯＣＨ＝ＣＨ_２）、ネオペンチルグリコールジグリシジルエーテルジ（メタ）アクリレート（ＣＨ_２＝ＣＨＣＯＯＣＨ_２ＣＨＯＨＣＨ_２ＯＣＨ_２Ｃ（ＣＨ_３）_２ＣＨ_２ＯＣＨ_２ＣＨＯＨＣＨ_２ＯＣＯＣＨ＝ＣＨ_２）
これらの化合物は、その（メタ）アクリロイル基により、硬化型樹脂の（メタ）アクリロイル基と親和し、その水酸基により、導電性ポリマーのエーテル結合又はイオン性基と親和して双方が単独で凝集するのを防止すると考えられる。このような観点から、分子形状が直鎖状で、分子の末端側に水酸基を持つ化合物が好ましく、分子中に多くの水酸基を持つものが特に好ましい。余り大きな分子は動きが悪く硬化型樹脂と導電性ポリマーの双方の形状変化に追随しにくく、相溶化剤としての効果が小さい。そのためＧＰＣを用いたポリスチレン標準により求められた平均重量分子量で１×１０^３以下が好ましい。また、塗料中の溶剤が揮散するときに最後まで溶解していることが重要である。また、入手しやすく、コスト的にも安いことも実用上重要な要素である。これらの諸観点からすると、２−ヒドロキシエチル（メタ）アクリレート、４−ヒドロキシブチル（メタ）アクリレートが特に好ましい。
なお、（メタ）アクリロイル基を３個以上持つ硬化型樹脂を、相溶化剤と用いずに単独で使用することもできるし（相溶化剤の相当物）、これを他の硬化型樹脂と併用することもできる。しかし、硬化型樹脂と導電性ポリマーとの相溶化剤としての機能は、その構造の複雑さ故余り大きくない。従って、これらを硬化型樹脂を使用する場合でも、直鎖状の（メタ）アクリロイル基を１個又は２個有する相溶化剤と併用する方が好ましい。
上記相溶化剤又はその相当物は、塗料組成物の硬化時の固形分に対し少なくとも５重量％使用することが好ましい。多量に使用するほど相溶性は高まり凝集物は少なくなるものの、硬化後の被膜の硬度が低下するので、上限はおよそ３０重量％である。勿論この量は、硬化型樹脂、導電性ポリマー及び相溶化剤の種類と、望まれる性能により実験で容易に決めることができる。
本発明の塗料組成物は、さらに、性能改良のため、本発明の効果を変えない範囲で、消泡剤、レベリング剤、酸化防止剤、紫外線吸収剤、光安定剤、重合禁止剤等を含有することができる。また、塗工層に防眩性を付与するため、本発明の効果を変えない範囲で、シリカ粒子やアクリル樹脂、シリコン樹脂、ウレタン樹脂等の樹脂ビーズ等、有機又は無機の微粒子を添加することもできる。
本発明の塗料組成物は、上記の成分を混合し、溶剤に溶解して作製する。塗布後に溶剤が残存していると硬化反応が遅くなり架橋密度が減少し、十分な硬化被膜が得にくい。従って、溶剤の粘度が高く、沸点の高いものは不適である。これらの観点から、溶剤として通常低分子のアルコールが好ましく、具体的にはエチルアルコール、プロピルアルコール、ブチルアルコールが好ましい。塗料組成物中の固形分の割合は通常１０〜７０重量％である。
本発明の帯電防止ハードコートフィルムは上述した塗料組成物を熱可塑性樹脂フィルム上に塗布して得られる。本発明の帯電防止ハードコートフィルムに使用する熱可塑性樹脂フィルムは、透明なシート又はフィルム状のものが好ましく、例えばポリエステルフィルム、ポリエチレンフィルム、ポリプロピレンフィルム、セロファンフィルム、ジアセチルセルロースフィルム、トリアセチルセルロースフィルム、アセチルセルロースブチレートフィルム、ポリ塩化ビニルフィルム、ポリ塩化ビニリデンフィルム、ポリビニルアルコールフィルム、ポリエチレンビニルアルコールフィルム、ポリスチレンフィルム、ポリカーボネートフィルム、ポリメチルペンチルフィルム、ポリスルフォンフィルム、ポリエーテルケトンフィルム、ポリエーテルスルフォンフィルム、ポリエーテルイミドフィルム、ポリイミドフィルム、フッ素樹脂フィルム、ナイロンフィルム、アクリルフィルム、ポリシクロペンタジエンフィルム等のポリシクロオレフィンフィルムなどを挙げることが出来るが、本発明においては、特に光学異方性が無いという特徴から液晶表示体に偏光板の部材として広く実用されている、トリアセチルセルロースフィルム（ＴＡＣフィルム）を使用することが好ましい。ＴＡＣフィルムは、通常、溶液キャスト法で製膜されるため平面性が悪く、かつ透明性が高いため、凝集等に起因した欠点がなく均一な塗工層を形成することが非常に困難である。本発明においては、このように透明性の高い透明な熱可塑性樹脂フィルム上に均一なハードコート層を形成する際に、特に効果が発現する。
本発明のハードコート層は、上記塗料組成物を適当な塗工装置を用いて熱可塑性樹脂フィルム上に塗工した後、紫外線又は放射線を照射して硬化することにより形成される。架橋密度の高い被膜を得るには、溶剤をできるだけ除去してから紫外線又は放射線を照射することが好ましい。塗工装置としては、マイクログラビアコーター、グラビアコーター、マイヤーバーコーター、ダイコーター等の公知の塗工装置を使用できる。塗工時の塗料組成物の粘度、濃度は使用する塗工装置により、適切な値に調整できる。硬化後のハードコート層の膜厚は通常１〜２０μｍ、好ましくは２〜１０μｍである。膜厚が厚いと帯電防止効果は大きいが、透明性が低下し、又はードコートフィルムにカールが発生しやすくなる。
本発明のハードコートフィルムは、特に透明性の高いディスプレイに使用するため、ハードコートフィルムのヘイズ値（ＪＩＳ Ｋ７１０５に準じて測定）は２．０％未満であることが好ましく、特に好ましくは１．０％である。また、高透明性と帯電防止性能を両立するという観点から、ハードコート層の表面抵抗率（ＪＩＳ Ｋ６９１１）は１．０×１０^１２Ω未満が好ましく、特に好ましくは１．０×１０^１１Ω未満である。
以下、実施例により本発明を例証するが、これらは本発明を制限することを意図したものではない。なお、同一の化合物については特記しないかぎり同一の製品を用いた。また、実施例中の「部」及び「％」は特に明示しない限り、それぞれ「重量部」及び「重量％」を表わす。
実施例１
実施例１〜６は、硬化型樹脂がペンタエリスリトールテトラアクリレート、導電性ポリマーが４級アンモニウム塩基含有メタクリレート共重合ポリマーとしたとき、これらを相溶させる相溶化剤として２−ヒドロキシエチルアクリレートの量が、本発明の課題にどのように影響するかを調べた。
７５μｍのポリエステルフィルム（Ａ−４３００；東洋紡績社製）の一方の面に、下記の塗料組成物１をバーコーターにて塗工し、６０℃のドライヤーで希釈溶剤を蒸発させた後、ＵＶ光を照射し、帯電防止ハードコートフィルムを得た。このときの塗工層の厚みは５μｍであった。
塗料組成物１
硬化型樹脂：ペンタエリスリトールテトラアクリレート（新中村化学工業社製、
ＮＫエステルＡ−ＴＭＭＴ） ４６．５部
導電性ポリマー：エレコンドＰＱ−５０Ｂ（綜研化学社製、４級アンモニウム塩
基含有（メタ）アクリレート共重合ポリマー、分子量：３×１０^４、メタノール
溶液、固形分５０％） ６０．０部
相溶化剤：２−ヒドロキシエチルアクリレート（共栄社油脂社製、ライトエステ
ルＨＯＡ、分子量：１１６） ２０．０部
開始剤：イルガキュア１８４（チバガイギー社製） ３．５部
溶剤 ：エタノール ７０．０部
添加剤：シロキサン系界面活性剤：ＢＹＫ−３００（ビックケミー社製）
対液０．０５部
塗料組成物は、溶媒エタノール中に、攪拌しながら他の化合物を順次添加し均一になるまで常温で溶解して作製した。
実施例２
塗料組成物１において、ペンタエリスリトールテトラアクリレートを５６．５部、２−ヒドロキシエチルアクリレートを１０部用いた他は実施例１と同様にして帯電防止ハードコートフィルムを得た。
実施例３
塗料組成物１において、ペンタエリスリトールテトラアクリレートを６０．５部、２−ヒドロキシエチルアクリレートを６部用いた他は実施例１と同様にして帯電防止ハードコートフィルムを得た。
実施例４
塗料組成物１において、ペンタエリスリトールテトラアクリレートを６１．５部、２−ヒドロキシエチルアクリレートを５部用いた他は実施例１と同様にして帯電防止ハードコートフィルムを得た。
実施例５
この実施例は、別の相溶化剤を使用した。
相溶化剤として２−ヒドロキシエチルアクリレートの代わりにヒドロキシブチルアクリレート２０部を使用した他は、実施例１と同様にして塗料組成物２を作製し、実施例１と同様にして帯電防止ハードコートフィルムを作製した。
実施例６
この実施例は、導電性ポリマーとして高分子量のものを用いた例である。
塗料組成物１の代わりに下記塗料組成物３を用いた以外は実施例１と同様に塗料調製後、帯電防止ハードコートフィルムを作製した。
塗料組成物３
硬化型樹脂：ペンタエリスリトールテトラアクリレート ４６．５部
導電性ポリマー：サフトマーＳＴ３６００（三菱化学社製、４級アンモニウム塩
基含有（メタ）アクリレート共重合ポリマー、分子量：１０×１０^４、メチルセ
ロソルブーメタノール溶液、固形分３５％） ６０．０部
相溶化剤：２−ヒドロキシエチルアクリレート ２０．０部
開始剤：イルガキュア１８４ ３．５部
溶剤：エタノール ６０．０部
添加剤：シロキサン系界面活性剤：ＢＹＫ−３００ 対液０．０５部
実施例７
実施例７と８は、実施例４とともに導電性ポリマーの配合量を変化させたときの例である。
塗料組成物１の代わりに下記塗料組成物４を用いた以外は実施例１と同様に塗料調製後、帯電防止ハードコートフィルムを作製した。導電性ポリマーと硬化型樹脂の合計固形分量が７６．５部となるようにして比較した。
塗料組成物４
硬化型樹脂：ペンタエリスリトールテトラアクリレート ６６．５部
導電性ポリマー：エレコンドＰＱ−５０Ｂ ２０．０部
相溶化剤：２−ヒドロキシエチルアクリレート ５．０部
開始剤：イルガキュア１８４ ３．５部
溶剤：エタノール ７０．０部
添加剤：シロキサン系界面活性剤：ＢＹＫ−３００ 対液０．０５部
実施例８
塗料組成物４において、ペンタエリスリトールテトラアクリレートを３６．５部、エレコンドＰＱ−５０Ｂを８０．０部用いた他は実施例７と同様にして帯電防止ハードコートフィルムを得た。
実施例９
この例は、相溶化剤として、多官能アクリレートを使用した例である。
実施例１で使用した塗料組成物１において、相溶化剤を２−ヒドロキシエチルアクリレート２０部の代わりに、ジペンタエリスリトールモノヒドロキシペンタアクリレート２０部を用いたものを塗料組成物５とし、実施例１と同様に塗料調製後、帯電防止ハードコートフィルムを作製した。
ジペンタエリスリトールモノヒドロキシペンタアクリレートは、分子量が５２４であり、サートマー社のＳＲ−３９９を用いた。
実施例１０
この例は、硬化型樹脂として水酸基を有する化合物を単独使用し、相溶化剤と兼用した例である。従って相溶化剤は別に配合していない。
下記塗料組成物６を用いた以外は実施例１と同様に塗料調製後、帯電防止ハードコートフィルムを作製した。
塗料組成物６
硬化型樹脂兼相溶化剤：ペンタエリスリトールトリアクリレート（新中村化学工
業社製、ＮＫエステルＡ−ＴＭＭ−３、分子量：２９８） ６６．５部
導電性ポリマー：エレコンドＰＱ−５０Ｂ ６０．０部
開始剤：イルガキュア１８４ ３．５部
溶剤：エタノール ７０．０部
添加剤：シロキサン系界面活性剤：ＢＹＫ−３００ 対液０．０５部
実施例１１
透明プラスティックフィルムとしてトリアセチルセルロースフィルムを用いた以外は実施例１と同様に塗料調整後、帯電防止ハードコートフィルムを作製した。
比較例１
これは、相溶化剤を全く使用しない場合の例である。
下記塗料組成物７を用いた以外は実施例１と同様に塗料調製後、帯電防止ハードコートフィルムを作製した。
塗料組成物７
硬化型樹脂：ペンタエリスリトールテトラアクリレート ６６．５部
導電性ポリマー：エレコンドＰＱ−５０Ｂ ６０．０部
開始剤：イルガキュア１８４ ３．５部
溶剤：エタノール ７０．０部
添加剤：シロキサン系界面活性剤：ＢＹＫ−３００ 対液０．０５部
比較例２
本比較例は、導電性ポリマーの代わりに、低分子量のカチオン性界面活性剤型導電剤（エレガンＴＯＦ ５０１−ＣＮ（日本油脂社製））を用いた例である。
下記塗料組成物８を用いた以外は実施例１と同様に塗料調製後、帯電防止ハードコートフィルムを作製した。
塗料組成物８
硬化型樹脂：ペンタエリスリトールテトラアクリレート ４６．５部
導電剤：エレガンＴＯＦ ５０１−ＣＮ（日本油脂社製） ２０．０部
相溶化剤：２−ヒドロキシエチルアクリレート ２０．０部
開始剤：イルガキュア１８４ ３．５部
溶剤：エタノール ７０．０部
添加剤：シロキサン系界面活性剤：ＢＹＫ−３００ 対液０．０５部
比較例３
本比較例は、導電性ポリマーの代わりに、超微粒のアンチモンをドープした酸化錫を導電剤として用いた例である。
下記塗料組成物９を用いた以外は実施例１と同様に塗料調製後、帯電防止ハードコートフィルムを作製した。
塗料組成物９
硬化型樹脂：ペンタエリスリトールテトラアクリレート ４６．５部
導電剤：アンチモンドープＳｎＯ_２（体積平均粒子径０．０９５μｍ）
２０．０部
相溶化剤：２−ヒドロキシエチルアクリレート ２０．０部
開始剤：イルガキュア１８４ ３．５部
溶剤：エタノール ７０．０部
添加剤：シロキサン系界面活性剤：ＢＹＫ−３００ 対液０．０５部
実施例１〜１１及び比較例１〜３で得られた塗料組成物及び帯電防止ハードコートフィルムについて、下記の評価を行なった。
（１）塗料組成物中の導電性ポリマー又は硬化型樹脂の凝集性
塗料調製後、目開き２０μｍのナイロンメッシュにて、ろ過した。メッシュ上に樹脂凝集が確認された場合は「あり」で示し、「不良」と判断される。
（２）塗工品の透明性
透明性は、可視光透過性より、くもり（ヘイズ）の程度が、高精細高輝度画面の鮮明性によく相関する。そのためフィルムについて、東洋精機社製ヘイズメーターを使用して、ＪＩＳ Ｋ７１０５に準じてヘイズ度及び透過度を測定した。透明性はヘイズ度を基に評価を行った。ヘイズ度が１．０％未満は「特に良好」、１．０以上２．０％未満は「良好」、２．０％以上は「不良」と判断される。
（３）塗工品の外観均一性
フィルムを通してバックライト光を観察し、塗工層に存在する凝集物の有無を観察し、視認により異物感を感じるのは１５０μｍ以上であることから、５００ｃｍ^２における大きさが１５０μｍ以上の凝集物の個数をカウントした。凝集物の個数が、５００ｃｍ^２あたり５個未満は「特に良好」、５個以上２０個未満は「良好」、２０個以上は「不良」と判断される。
（４）帯電防止性
三菱化学社製高抵抗率計（Ｈｉｒｅｓｔａ−ＵＰ）を使用し、フィルムの表面抵抗率（Ω）を測定した。表面抵抗率を基に帯電防止性の評価を行った。表面抵抗率が１．０×１０^１１Ω未満は「特に良好」、１．０×１０^１１以上１．０×１０^１２Ω未満は「良好」、１．０×１０^１２以上は「不良」と判断される。
（５）鉛筆硬度（ハードコート性）
東洋精機（株）製鉛筆硬度試験器を使用し、ＪＩＳ Ｋ５４００に準拠してフィルムの鉛筆硬度を測定した。鉛筆硬度がＨは「良好」、ＨＢは「不良」と判断される。
（６）帯電防止効果の持続性
ハードコートフィルムを、９０℃の乾燥機内に２５０時間放置後、ハードコート表面に油状のものがあらわれ、導電剤のブリードアウトが確認された場合は「有り」、確認されなかった場合は「無し」とした。「有り」の場合は「不良」と判断される。
評価結果を下記表１に示す。

表１において、相溶化剤を全く含有しない比較例１と比べ、相溶化剤を含む実施例１〜５は、塗料中の凝集物、塗工品の外観均一性、透明性（ヘイズ）が極めて優れていることが分かる。また、導電剤として低分子の界面活性剤を使用した比較例２と実施例１〜５を比較すれば、本発明の導電性ポリマーを使用することにより、極めて高温長時間でも帯電防止効果が持続するという顕著な効果が見られる。硬化型樹脂がペンタエリスリトールテトラアクリレートで、導電性ポリマーが４級アンモニウム塩基含有アクリレート共重合体であって、相溶化剤がヒドロキシエチルアクリレートの場合は、被膜固形分の５％以上相溶化剤を含有する場合、顕著に凝集性が改善されることが分かる。また、導電性ポリマーの硬化型樹脂に対する使用量がある適当な範囲があることが分かる。この例の場合は、１０〜４０％の配合が適当であった。この範囲であれば、塗料組成物を塗布してハードコート層を形成させると、高い透明性、帯電防止性、均一性、耐擦傷性、耐薬品性に優れたハードコートフィルムを得ることができることが分かる。 Technical field
The present invention relates to a coating composition for forming a conductive hard coat layer, and an antistatic hard coat film obtained by applying and curing the composition on a thermoplastic resin film. The present invention relates to an antistatic hard coat film suitable for protecting the surface of an electronic information display body such as the above-mentioned screen display.
Conventional technology
Various display bodies such as liquid crystal displays, CRTs, plasma displays, outdoor display panels, and electric bulletin boards or glass use a thermoplastic resin film subjected to a hard coat treatment in order to protect the surface. Since the thermoplastic resin film has a high volume resistivity, it easily takes static electricity on the contact surface due to friction, and does not leak. For this reason, productivity during the display assembly process is lowered by static electricity itself or dust adsorption due to static electricity. Or when actually used as a display body, there is a problem that the visibility is remarkably lowered due to the adsorption of dust on the surface.
In order to improve these problems, the surfactant is kneaded into the thermoplastic resin as a conductive agent, or added to the paint and applied to the surface of the thermoplastic resin film or molded article to increase the conductivity and prevent static charge. Has been done.
When a surfactant is kneaded with a thermoplastic resin, the thermoplastic resin generally has a low polarity, a poor compatibility with a surfactant with a high polarity, and a low molecular weight of the surfactant. As the process progresses, the surfactant bleeds out to the surface of the thermoplastic resin, surface tackiness occurs, and at the same time, the transparency is lowered and the antistatic property is lowered. is there.
In addition, when a surfactant is applied to the film surface as a paint together with a hard coat agent, the low molecular surfactant will cause tackiness on the surface, and the antistatic effect will decrease over time due to the action of temperature and humidity, light, etc. However, there is a problem that the antistatic effect is inferior in weather resistance or durability.
In order to prevent performance degradation due to bleed out or surface mobility, high molecular weight type conductive polymers have been put into practical use. The conductive polymer has a conductive unit in the molecule. The conductive unit is a highly polar hydrophilic group such as an ionic group or a low molecular weight ether that is bonded to a polymer to impart conductivity.
However, when a highly polar conductive polymer is kneaded with a thermoplastic resin, the compatibility with the low polarity thermoplastic resin is poor, the appearance is uneven due to the conductive polymer not being uniformly dispersed, and the transparency is reduced ( Haze is generated), and both the conductive polymer and the thermoplastic resin are not sufficiently hard, and particularly when used for protecting the display surface of electronic information, it becomes a serious problem.
In addition, when conductive polymer and hard coat agent are applied to the film surface as a paint, there is no problem with bleed-out, but conductive polymer often agglomerates, resulting in non-uniform appearance and reduced transparency due to this aggregate. (Haze generation) occurs. In particular, a film that protects the surface of an electronic information display has important requirements for non-coloring and non-fogging transparency as a whole, in addition to conductivity, durability of its effect, and hard coat properties. The transparent hard coat film uses an ultraviolet or radiation curable resin having a high crosslinking density, and this curable resin is a coating mainly composed of a monomer or oligomer that is polymerized and cured by irradiation with ultraviolet or radiation. It is produced by irradiating with ultraviolet rays or radiation. When the chargeable polymer is mixed and dissolved in the paint and applied to the film surface, the conductive polymer often agglomerates as the solvent evaporates, and the film becomes cloudy (haze) due to the aggregate of the conductive polymer. As a result, there was a problem that transparency, appearance uniformity, or visibility deteriorated.
As described above, the use of the conductive polymer still has a problem requiring improvement.
In addition, the following techniques are known as techniques other than the conductive polymer that improve the problem of using a surfactant as a conductive agent.
For example, in JP-A-6-263903, metal oxide ultrafine particles doped with antimony are used for the purpose of reducing the humidity dependence of the conductivity of the resin panel and improving the durability of the transparency of the coating. A technique for applying and curing a paint on the surface of a resin panel is disclosed.
Japanese Patent Application Laid-Open No. 6-87965 discloses quaternary ammonium sulfonate for the purpose of forming a transparent and conductive film having excellent weather resistance on the surface of a synthetic resin molded product such as an optical disk or a video tape. A technique for photopolymerizing and curing a monofunctional (meth) acryloyl compound having a base together with a crosslinkable oligomer is disclosed. In addition, JP 2000-282014 A discloses a hydrolyzate of a quaternary ammonium structure-containing silane compound for forming a photo-curing type antistatic hard coat film on a plastic surface such as an automobile part, an organic sheet glass, or a signboard. , A technique of photopolymerizing and curing a mixture of hydrolyzate of (meth) acryloyl functional silane together with polyfunctional (meth) acrylate is disclosed.
Problems to be solved by the invention
However, it has been found that each of the above known techniques has the following problems.
In the technique described in Japanese Patent Laid-Open No. 6-26039, the coating formed from this paint has coloring due to absorption in the visible light region of the metal oxide ultrafine particles, and the decrease in transparency at a specific wavelength is large. It is not suitable for use on the surface of an electronic information display such as a CRT.
Although the technique described in Japanese Patent Laid-Open No. 6-87965 can ensure conductivity with a relatively small amount of use, the hard coat property is insufficient. If the hard coat property is ensured, the conductivity becomes insufficient.
The technology of JP-A-2000-282014 uses a special silane compound and has a considerable amount of time to obtain a hydrolyzate thereof, industrially complicated processes and poor productivity. The compound has a problem that it has no resistance to alkaline chemicals.
Thus, it has been difficult to obtain an antistatic hard coat film that can withstand use even in an electronic information display.
Therefore, the present invention is not only excellent in antistatic property, transparency (no fogging), scratch resistance (hard coat property) and its durability and chemical resistance, but also has a non-colored and no cloudy hard coat layer. It is an object of the present invention to provide a coating composition that can be formed continuously and uniformly, and an antistatic hard coat film having a hard coat layer formed by applying the composition and curing it with ultraviolet rays or radiation.
Means for solving the problem
The inventors have made research on reducing the cohesiveness of the conductive polymer, which is the cause of the above problem, by taking advantage of the convenience of using the conductive polymer. As a result, a compound having at least one (meth) acryloyl group and at least one hydroxyl group as a component of a monomer or oligomer that is polymerized and cured by ultraviolet rays or radiation to form a hard coat resin film (ie, a compatibilizing agent) It was found that the above-mentioned problems can be solved by using as an essential component, and the present invention was completed.
That is, the present invention relates to an ultraviolet or radiation curable resin having at least three (meth) acryloyl groups, a conductive polymer, and a compatibilization having one or two (meth) acryloyl groups and at least one hydroxyl group. When the ultraviolet or radiation curable resin has a hydroxyl group in its molecule, it is a coating composition that does not need to contain the compatibilizer. Here, the (meth) acryloyl group is an expression including both an acryloyl group and a methacryloyl group. Further, the ultraviolet or radiation curable resin refers to a monomer / oligomer for forming a hard coat layer by irradiation with ultraviolet or radiation, and may contain a hydroxyl group. This coating composition does not contain a compatibilizing agent when the ultraviolet or radiation curable resin has a hydroxyl group in the molecule, because the ultraviolet or radiation curable resin has a function of a compatibilizing agent. May be. That is, the ultraviolet or radiation curable resin is an equivalent of a compatibilizing agent. The coating composition may contain a compatibilizing agent even when the ultraviolet or radiation curable resin has a hydroxyl group in its molecule.
The feature of the present invention is that a compound having a hydroxyl group and a (meth) acryloyl group is an essential component. This compound is considered to function as a compatibilizer between the ultraviolet or radiation curable resin and the conductive polymer. As a result, the cohesiveness of the conductive polymer can be improved, and an antistatic hard coat film having no haze or coloration and uniform and excellent visibility can be obtained. However, when the ultraviolet ray or radiation curable resin itself has a hydroxyl group, the object can be achieved by itself, and in order to further improve the aggregation of the conductive polymer, the ultraviolet ray or radiation curable resin and this compound are used. (That is, a compatibilizer) may be used in combination.
In this coating composition, the conductive polymer is substantially any one of a polyether, a quaternary ammonium base-containing polymer, a sulfonic acid-containing polymer, or a polymer charge transfer type binder polymer. This conductive polymer is preferably a quaternary ammonium base-containing polymer, more preferably a quaternary ammonium base-containing (meth) acrylate copolymer. Quaternary ammonium base-containing polymers are readily available and have good conductivity efficiency.
In this coating composition, the molecular weight of the conductive polymer is 2 × 10.⁴~ 50x10⁴It is preferable that If the molecular weight is smaller than this range, there is a high risk of bleed out particularly at high temperatures. If it is larger than this range, a large amount is required to obtain the necessary conductivity, and the hardness of the coating is relatively lowered. .
The ratio of the conductive polymer to the solid content at the time of curing of the coating composition is preferably 10 to 40% by weight.
Oligomers are generally used as ultraviolet or radiation curable resins. When the ultraviolet ray or radiation curable resin is an oligomer, the reaction is accelerated, and a certain flexibility is imparted to the formed film to prevent adhesion to the support and cracking of the film. However, in the present invention, the use of an oligomer is not essential, and instead a conductive polymer is considered to play its role.
The compatibilizer is a monomer that is polymerized or cured by ultraviolet rays or radiation, or a molecular weight of 1 × 10³The following oligomers are preferred. This monomer or oligomer may be the same as or different from the ultraviolet or radiation curable resin used in the coating composition.
Moreover, it is preferable that the ratio of the compatibilizer or its equivalent with respect to solid content at the time of hardening of the said coating composition is 5 weight% or more. This equivalent means an ultraviolet or radiation curable resin having a hydroxyl group in the molecule when the compatibilizer is omitted from the coating composition. The required amount of the compatibilizing agent or its equivalent is not necessarily constant depending on the type of ultraviolet or radiation curable resin or conductive polymer used, but from many experiments, if the coating solids content is 5% by weight or more, aggregation occurs. When the amount is extremely small and less than that, aggregation often becomes remarkable. In order to improve the cohesiveness of the conductive polymer and form a uniform and highly visible film, it is usually appropriate to make it 20% by weight or less of the solid content of the film.
The present invention also provides an antistatic hard coat having a conductive hard coat layer formed by applying any of the coating compositions described above on at least one surface of a plastic resin film and curing it by irradiation with ultraviolet rays or radiation. It is a film. Ultraviolet rays refer to electromagnetic waves having a wavelength in the range of about 1 to 390 nm, and radiation refers to three types of alpha rays, beta rays and gamma rays, and particle rays and cosmic rays having energy comparable to these. This antistatic hard coat film is colorless and transparent with no cloudiness, and is suitable for protecting the surface of electronic information display bodies such as CRTs and liquid crystal displays, and also withstands harsh environments. It can also be used as a protective film for information display bodies in harsh environmental conditions such as in places where automobiles are handled and in outdoor summer cars.
This plastic resin film is preferably triacetylcellulose. Among the thermoplastic resin films, the triacetyl cellulose film exhibits the effect of the present invention most remarkably.
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the ultraviolet or radiation curable resin is referred to as “curable resin”.
The curable resin used in the present invention is not particularly limited as long as it is a resin that has at least three (meth) acryloyl groups and is cured by irradiation with radiation or ultraviolet rays. Resin), urethane acrylate, polyester acrylate, epoxy acrylate, and the like. The curable resin used in the present invention may be one kind or a mixture of two or more kinds, and in the case of two or more kinds, a mixture of those having a hydroxyl group and those having no hydroxyl group may be used.
The following can be illustrated as typical examples. However, in addition to these, it is described in published books (for example, UV / EB Handbook (raw materials) 1985 Kobunshi Publishing Co., Ltd., Photosensitive Material List Book 1996, Bunshin Publishing). Can be used. In the following compounds, (meth) acrylate includes both acrylate and methacrylate, and all structural formulas are represented by acrylate.
As a polyol poly (meth) acrylate system:
(A) trimethylolpropane tri (meth) acrylate (the following formula),

(B) ditrimethylolpropane tetra (meth) acrylate (the following formula),

(C) pentaerythritol tetra (meth) acrylate (following formula),

(D) Dipentaerythritol hexa (meth) acrylate (the following formula)

(E) ethylene oxide-modified tri (meth) acrylate phosphate (the following formula),

(F) Pentaerythritol tri (meth) acrylate (the following formula)

(G) Dipentaerythritol monohydroxypenta (meth) acrylate (following formula)

(H) Epichlorohydrin-modified glycerol tri (meth) acrylate (the following formula)

(I) Epichlorohydrin-modified trimethylolpropane tri (meth) acrylate (following formula)

As an isocyanurate system:
(J) Tris (acryloxyethyl) isocyanurate (following formula),

Polyester (meth) acrylate, polyhydric alcohol, polyvalent isocyanate and hydroxyl group-containing (meth) which can be obtained by esterifying polyhydric alcohol and polyhydric carboxylic acid and / or anhydride and (meth) acrylic acid The polyurethane (meth) acrylate obtained by making an acrylate react is mentioned.
Of the curable resins having three or more (meth) acryloyl groups, when a compound having no hydroxyl group is used, a compound having a hydroxyl group and a (meth) acryloyl group as shown below must be used in combination. When the curable resin has 3 or more (meth) acryloyl groups and also a hydroxyl group, it can be used as a paint only with these compounds and a conductive polymer. Even in such a case, it is preferable to use a compatibilizing agent in combination from the viewpoint of compatibility, and it is preferable for stabilizing the coating, and aggregation of the conductive polymer can be prevented.
All of these compounds react with the irradiation of ultraviolet rays or radiation to form a three-dimensional structure, and thus become a structural component of the hard coat film. Therefore, the amount used is preferably 50 to 80% by weight based on the solid content at the time of curing of the coating composition. When performing a curing reaction with ultraviolet rays, a photopolymerization initiator (hereinafter referred to as “initiator”) is required, and a benzophenone initiator, a diketone initiator, an acetophenone initiator, a benzoin initiator, a thioxanthone initiator. Any known initiator such as an agent and a quinone initiator may be used. Usually, the initiator is used in an amount of 1 to 10% by weight based on the curable resin.
On the other hand, when the curing reaction is performed with radiation, an initiator is not necessary.
The conductive polymer used in the present invention is used for the purpose of imparting antistatic performance to the hard coat layer, and examples thereof include the following compounds.
As the polyether, polyalkylene oxide, polyether ester amide, alkylene oxide-epihalohydrin copolymer, methoxypolyalkylene glycol (meth) acrylate copolymer and the like can be used, and as alkylene, ethylene, propylene, or Those containing both of these are preferred.
The quaternary ammonium base-containing polymer may be any polymer that contains a quaternary ammonium base, preferably a quaternary ammonium salt. The quaternary ammonium salt is a salt of quaternary ammonium with an acid, halogen, or the like, and the acid is preferably a halogen acid such as sulfonic acid or hydrochloric acid.
Examples of the quaternary ammonium base-containing polymer are shown below together with typical structural formulas (wherein l, m, and n each represents an appropriate integer).
(1) Quaternary ammonium base-containing (meth) acrylate copolymer (compound obtained by copolymerizing (meth) acrylate having a quaternary ammonium base in a part of a polymer composed of styrene, acrylonitrile, butadiene, vinyl chloride or a mixture thereof. )

(2) A quaternary ammonium base-containing maleimide copolymer (compound obtained by copolymerizing a maleimide having a quaternary ammonium base in a part of a polymer comprising styrene, acrylonitrile, butadiene or a mixture thereof)

(3) Quaternary ammonium base-containing methacrylimide copolymer (compound having a quaternary ammonium base in a part of a copolymer of acrylate, methacrylate and methacrylamide)

(4) Quaternary ammonium base-containing carbobetaine graft copolymer (compound in which carbobetaine having a quaternary ammonium salt bonded to polyethylene or polypropylene is grafted)

As the sulfonic acid-containing polymer, a polymer containing sulfonic acid in the form of a sulfonate is preferable, and examples thereof include polystyrene sulfonate soda, a copolymer thereof with acrylonitrile, butadiene, and a mixture thereof.
Among these conductive polymers, polyether, quaternary ammonium base-containing polymer and sulfonic acid-containing polymer are preferable, quaternary ammonium base-containing polymer is more preferable, and quaternary ammonium base-containing (meth) acrylate copolymer is particularly preferable. It is particularly preferable because it has high conductivity, is commercially available in many types, has a variety of types of base polymers, and can easily select one having a high affinity with a curable resin.
The average weight molecular weight of the conductive polymer was determined by a polystyrene standard using gel permeation chromatography (GPC), 2 × 10⁴~ 50x10⁴Is preferred, more preferably 2 × 10⁴~ 30x10⁴It is. If the molecular weight is too small, the film-forming property is low and is likely to cause blocking, and if the molecular weight is too large, the compatibility with the curable resin is poor, resulting in a non-uniform paint and aggregation in the solvent volatilization process. Things occur frequently.
The content of the conductive polymer is preferably 10 to 40% by weight with respect to the solid content when the hard coat layer coating is cured. If the content of the conductive polymer is too small, water molecules will not be sufficiently adsorbed on the surface and antistatic performance will not be exhibited. On the other hand, when the content is too large, the ratio of the curable resin is relatively reduced, so that the hard coat property (scratch resistance) is significantly reduced. Further, by using an amount in this range, it is possible to impart moderate flexibility and impact resistance to the hard coat layer and improve adhesion.
The curable resin and the conductive polymer have poor compatibility because of the large difference in polarity as described above, and these are used as a paint together with a solvent, and the conductive polymer aggregates in the process of coating and drying on the film. make. A compatibilizing agent having a hydroxyl group and a (meth) acryloyl group or an equivalent thereof is used in combination with the curable resin so as to prevent aggregation between the conductive polymers.
Examples of the compatibilizer having such an action are given below.
All structural formulas are shown as acrylates, but (meth) acrylates can be used as well.
(A) Compound having one hydroxyl group and one (meth) acryloyl group:
2-hydroxyethyl (meth) acrylate (CH₂= CHCOOCH₂CH₂OH), 2-hydroxypropyl (meth) acrylate (CH₂= CHCOOCH₂CHOHCH₃), 4-hydroxybutyl (meth) acrylate (CH₂= CHCOOCH₂CH₂CH₂CH₂OH), 2-hydroxy-3-phenoxypropyl (meth) acrylate (following formula)

, Ethylene oxide modified phthalic acid (meth) acrylate (following formula)

, Polypropylene glycol (meth) acrylate (CH₂= CHCO (OCH₂CHCH₃)₁₂OH),
(B) Compound having one hydroxyl group and two (meth) acryloyl groups:
Glycerol di (meth) acrylate (CH₂= CHCOOCH₂CHOHCH₂OCOCH = CH₂), Ethylene oxide-modified di (meth) acrylate phosphate (the following formula)

(C) Compound having two hydroxyl groups and one (meth) acryloyl group:
Ethylene oxide modified phosphoric acid (meth) acrylate (following formula)

Glycerol (meth) acrylate (CH₂= CHCOOCH₂CHOHCH₂OH)
(D) Compound having two hydroxyl groups and two (meth) acryloyl groups:
Epichlorohydrin-modified 1,6-hexanediol di (meth) acrylate (CH₂= CHCOOCH₂CHOHCH₂O (CH₂)₆OCH₂CHOHCH₂OCOCH = CH₂), Epichlorohydrin modified diethylene glycol di (meth) acrylate (CH₂= CHCOOCH₂CHOHCH₂O (CH₂CH₂O)₂CH₂CHOHCH₂OCOCH = CH₂), Epichlorohydrin-modified phthalic acid di (meth) acrylate (following formula)

, Epichlorohydrin modified propylene glycol di (meth) acrylate (CH₂= CHCOOCH₂CHOHCH₂OCHCH₃CH₂OCH₂CHOHCH₂OCOCH = CH₂), Neopentyl glycol diglycidyl ether di (meth) acrylate (CH₂= CHCOOCH₂CHOHCH₂OCH₂C (CH₃)₂CH₂OCH₂CHOHCH₂OCOCH = CH₂)
These compounds have an affinity with the (meth) acryloyl group of the curable resin by the (meth) acryloyl group, and by the hydroxyl group, they have an affinity for an ether bond or an ionic group of the conductive polymer, and both of them are aggregated alone. It is thought to prevent this. From such a viewpoint, a compound having a linear molecular shape and having a hydroxyl group on the terminal side of the molecule is preferable, and a compound having many hydroxyl groups in the molecule is particularly preferable. Too large molecules do not move well and are difficult to follow changes in the shape of both the curable resin and the conductive polymer, and the effect as a compatibilizer is small. Therefore, the average weight molecular weight determined by the polystyrene standard using GPC is 1 × 10³The following is preferred. It is also important that the solvent in the paint dissolves to the end when it volatilizes. In addition, it is easy to obtain and low in cost. From these viewpoints, 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate are particularly preferable.
In addition, a curable resin having 3 or more (meth) acryloyl groups can be used alone without using a compatibilizer (equivalent to the compatibilizer) or used in combination with other curable resins. You can also However, the function as a compatibilizing agent between the curable resin and the conductive polymer is not so large due to the complexity of the structure. Therefore, it is preferable to use these in combination with a compatibilizing agent having one or two linear (meth) acryloyl groups even when a curable resin is used.
The compatibilizing agent or its equivalent is preferably used in an amount of at least 5% by weight based on the solid content at the time of curing of the coating composition. The higher the amount used, the higher the compatibility and the fewer the aggregates, but the lower the hardness of the film after curing, the upper limit is about 30% by weight. Of course, this amount can be easily determined experimentally depending on the type of curable resin, conductive polymer and compatibilizer and the desired performance.
The coating composition of the present invention further contains an antifoaming agent, a leveling agent, an antioxidant, an ultraviolet absorber, a light stabilizer, a polymerization inhibitor, etc. within a range that does not change the effect of the present invention for performance improvement. can do. In addition, in order to impart antiglare properties to the coating layer, organic or inorganic fine particles such as silica particles, resin beads such as acrylic resin, silicon resin, and urethane resin are added within a range that does not change the effect of the present invention. You can also.
The coating composition of the present invention is prepared by mixing the above components and dissolving in a solvent. If the solvent remains after coating, the curing reaction slows down, the crosslinking density decreases, and it is difficult to obtain a sufficient cured film. Accordingly, a solvent having a high viscosity and a high boiling point is not suitable. From these viewpoints, a low molecular alcohol is usually preferable as a solvent, and specifically, ethyl alcohol, propyl alcohol, and butyl alcohol are preferable. The ratio of the solid content in the coating composition is usually 10 to 70% by weight.
The antistatic hard coat film of the present invention is obtained by applying the above-described coating composition on a thermoplastic resin film. The thermoplastic resin film used for the antistatic hard coat film of the present invention is preferably a transparent sheet or film, such as a polyester film, a polyethylene film, a polypropylene film, a cellophane film, a diacetylcellulose film, a triacetylcellulose film, Acetyl cellulose butyrate film, polyvinyl chloride film, polyvinylidene chloride film, polyvinyl alcohol film, polyethylene vinyl alcohol film, polystyrene film, polycarbonate film, polymethylpentyl film, polysulfone film, polyether ketone film, polyether sulfone film, Polyetherimide film, polyimide film, fluororesin film, nylon film Polycycloolefin films such as rum, acrylic film, polycyclopentadiene film, etc. can be mentioned, but in the present invention, it is widely used as a polarizing plate member for liquid crystal displays due to the characteristic that there is no optical anisotropy. It is preferable to use a triacetyl cellulose film (TAC film). A TAC film is usually formed by a solution casting method and thus has poor flatness and high transparency, so that it is very difficult to form a uniform coating layer without defects due to aggregation or the like. . In the present invention, when the uniform hard coat layer is formed on the transparent thermoplastic resin film having high transparency as described above, the effect is particularly manifested.
The hard coat layer of the present invention is formed by coating the above-mentioned coating composition on a thermoplastic resin film using an appropriate coating apparatus and then curing it by irradiation with ultraviolet rays or radiation. In order to obtain a film having a high crosslinking density, it is preferable to irradiate with ultraviolet rays or radiation after removing the solvent as much as possible. As the coating apparatus, known coating apparatuses such as a micro gravure coater, a gravure coater, a Meyer bar coater, and a die coater can be used. The viscosity and concentration of the coating composition at the time of coating can be adjusted to appropriate values depending on the coating apparatus used. The film thickness of the hard coat layer after curing is usually 1 to 20 μm, preferably 2 to 10 μm. When the film thickness is thick, the antistatic effect is large, but the transparency is lowered, or curd is likely to occur in the coated film.
Since the hard coat film of the present invention is used for a display with particularly high transparency, the hard coat film preferably has a haze value (measured according to JIS K7105) of less than 2.0%, particularly preferably 1. 0%. Further, from the viewpoint of achieving both high transparency and antistatic performance, the surface resistivity (JIS K6911) of the hard coat layer is 1.0 × 10 6.¹²Less than Ω is preferable, and 1.0 × 10 is particularly preferable.¹¹Less than Ω.
The invention will now be illustrated by the following examples, which are not intended to limit the invention. The same product was used for the same compound unless otherwise specified. Further, “parts” and “%” in the examples represent “parts by weight” and “% by weight”, respectively, unless otherwise specified.
Example 1
In Examples 1 to 6, when the curable resin is pentaerythritol tetraacrylate and the conductive polymer is a quaternary ammonium base-containing methacrylate copolymer, the amount of 2-hydroxyethyl acrylate is a compatibilizing agent for compatibilizing them. The influence of the problems of the present invention was investigated.
The following coating composition 1 was applied to one surface of a 75 μm polyester film (A-4300; manufactured by Toyobo Co., Ltd.) with a bar coater, and the diluted solvent was evaporated with a dryer at 60 ° C. To obtain an antistatic hard coat film. The thickness of the coating layer at this time was 5 μm.
Coating composition 1
Curable resin: Pentaerythritol tetraacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.,
NK Ester A-TMMT) 46.5 parts
Conductive polymer: Elecondo PQ-50B (manufactured by Soken Chemical Co., Ltd., quaternary ammonium salt
Group-containing (meth) acrylate copolymer, molecular weight: 3 × 10⁴,methanol
Solution, solid content 50%) 60.0 parts
Compatibilizer: 2-hydroxyethyl acrylate (Kyoeisha Yushi Co., Ltd., Light Este
HOA, molecular weight: 116) 20.0 parts
Initiator: Irgacure 184 (Ciba Geigy) 3.5 parts
Solvent: Ethanol 70.0 parts
Additive: Siloxane-based surfactant: BYK-300 (manufactured by Big Chemie)
0.05 part against liquid
The coating composition was prepared by sequentially adding other compounds in the solvent ethanol while stirring and dissolving at room temperature until uniform.
Example 2
An antistatic hard coat film was obtained in the same manner as in Example 1 except that 56.5 parts of pentaerythritol tetraacrylate and 10 parts of 2-hydroxyethyl acrylate were used in the coating composition 1.
Example 3
An antistatic hard coat film was obtained in the same manner as in Example 1 except that 60.5 parts of pentaerythritol tetraacrylate and 6 parts of 2-hydroxyethyl acrylate were used in the coating composition 1.
Example 4
An antistatic hard coat film was obtained in the same manner as in Example 1 except that 61.5 parts of pentaerythritol tetraacrylate and 5 parts of 2-hydroxyethyl acrylate were used in the coating composition 1.
Example 5
This example used another compatibilizer.
A coating composition 2 was prepared in the same manner as in Example 1 except that 20 parts of hydroxybutyl acrylate was used instead of 2-hydroxyethyl acrylate as a compatibilizing agent, and an antistatic hard coat film was prepared in the same manner as in Example 1. Was made.
Example 6
In this example, a conductive polymer having a high molecular weight is used.
An antistatic hard coat film was prepared after preparing a paint in the same manner as in Example 1 except that the following paint composition 3 was used instead of the paint composition 1.
Coating composition 3
Curable resin: 46.5 parts of pentaerythritol tetraacrylate
Conductive polymer: Saftomer ST3600 (manufactured by Mitsubishi Chemical Corporation, quaternary ammonium salt
Group-containing (meth) acrylate copolymer, molecular weight: 10 × 10⁴, Methyl
Rosolve methanol solution, solid content 35%) 60.0 parts
Compatibilizer: 2-hydroxyethyl acrylate 20.0 parts
Initiator: Irgacure 184 3.5 parts
Solvent: ethanol 60.0 parts
Additive: Siloxane-based surfactant: BYK-300 0.05 part of liquid
Example 7
Examples 7 and 8 are examples when the blending amount of the conductive polymer is changed together with Example 4.
An antistatic hard coat film was prepared after preparing a paint in the same manner as in Example 1 except that the following paint composition 4 was used instead of the paint composition 1. Comparison was made such that the total solid content of the conductive polymer and the curable resin was 76.5 parts.
Coating composition 4
Curable resin: 66.5 parts of pentaerythritol tetraacrylate
Conductive polymer: 20.0 parts of Elecondo PQ-50B
Compatibilizing agent: 5.0 parts of 2-hydroxyethyl acrylate
Initiator: Irgacure 184 3.5 parts
Solvent: 70.0 parts of ethanol
Additive: Siloxane-based surfactant: BYK-300 0.05 part of liquid
Example 8
An antistatic hard coat film was obtained in the same manner as in Example 7 except that 36.5 parts of pentaerythritol tetraacrylate and 80.0 parts of Elecondo PQ-50B were used in the coating composition 4.
Example 9
In this example, a polyfunctional acrylate is used as a compatibilizing agent.
In the coating composition 1 used in Example 1, 20 parts of dipentaerythritol monohydroxypentaacrylate was used as the coating composition 5 instead of 20 parts of 2-hydroxyethyl acrylate as the compatibilizing agent. In the same manner as described above, an antistatic hard coat film was prepared after preparing the paint.
Dipentaerythritol monohydroxypentaacrylate has a molecular weight of 524, and SR-399 manufactured by Sartomer was used.
Example 10
In this example, a compound having a hydroxyl group is used alone as a curable resin and is also used as a compatibilizing agent. Therefore, no compatibilizer is blended separately.
An antistatic hard coat film was prepared after preparing a paint in the same manner as in Example 1 except that the following paint composition 6 was used.
Coating composition 6
Curable resin and compatibilizer: Pentaerythritol triacrylate (Shin Nakamura Chemical
NK Ester A-TMM-3, molecular weight: 298) 66.5 parts
Conductive polymer: Elicon PQ-50B 60.0 parts
Initiator: Irgacure 184 3.5 parts
Solvent: 70.0 parts of ethanol
Additive: Siloxane-based surfactant: BYK-300 0.05 part of liquid
Example 11
An antistatic hard coat film was prepared after adjusting the paint in the same manner as in Example 1 except that a triacetylcellulose film was used as the transparent plastic film.
Comparative Example 1
This is an example where no compatibilizer is used.
An antistatic hard coat film was prepared after preparing a paint in the same manner as in Example 1 except that the following paint composition 7 was used.
Coating composition 7
Curable resin: 66.5 parts of pentaerythritol tetraacrylate
Conductive polymer: Elicon PQ-50B 60.0 parts
Initiator: Irgacure 184 3.5 parts
Solvent: 70.0 parts of ethanol
Additive: Siloxane-based surfactant: BYK-300 0.05 part of liquid
Comparative Example 2
In this comparative example, a low molecular weight cationic surfactant type conductive agent (Elegan TOF 501-CN (manufactured by NOF Corporation)) is used instead of the conductive polymer.
An antistatic hard coat film was prepared after preparing a paint in the same manner as in Example 1 except that the following paint composition 8 was used.
Coating composition 8
Curable resin: 46.5 parts of pentaerythritol tetraacrylate
Conductive agent: Elegan TOF 501-CN (manufactured by NOF Corporation) 20.0 parts
Compatibilizer: 2-hydroxyethyl acrylate 20.0 parts
Initiator: Irgacure 184 3.5 parts
Solvent: 70.0 parts of ethanol
Additive: Siloxane-based surfactant: BYK-300 0.05 part of liquid
Comparative Example 3
In this comparative example, tin oxide doped with ultrafine antimony is used as the conductive agent instead of the conductive polymer.
An antistatic hard coat film was prepared after preparing a paint in the same manner as in Example 1 except that the following paint composition 9 was used.
Coating composition 9
Curable resin: 46.5 parts of pentaerythritol tetraacrylate
Conductive agent: antimony-doped SnO₂(Volume average particle diameter 0.095 μm)
20.0 parts
Compatibilizer: 2-hydroxyethyl acrylate 20.0 parts
Initiator: Irgacure 184 3.5 parts
Solvent: 70.0 parts of ethanol
Additive: Siloxane-based surfactant: BYK-300 0.05 part of liquid
The following evaluation was performed about the coating composition and antistatic hard coat film obtained in Examples 1-11 and Comparative Examples 1-3.
(1) Cohesiveness of conductive polymer or curable resin in coating composition
After preparing the paint, it was filtered with a nylon mesh having an opening of 20 μm. When resin aggregation is confirmed on the mesh, it is indicated as “present” and judged as “defective”.
(2) Transparency of coated products
As for transparency, the degree of cloudiness (haze) correlates well with the sharpness of a high-definition, high-luminance screen rather than visible light transmittance. Therefore, the haze degree and the transmittance | permeability were measured about the film according to JISK7105 using the Toyo Seiki company haze meter. Transparency was evaluated based on the degree of haze. A haze degree of less than 1.0% is judged as “particularly good”, 1.0 to less than 2.0% as “good”, and 2.0% or more as “bad”.
(3) Appearance uniformity of coated products
Observe the backlight through the film, observe the presence or absence of agglomerates present in the coating layer, and feel the foreign body feeling by visual recognition is more than 150μm, 500cm²The number of aggregates having a size of 150 μm or more was counted. The number of aggregates is 500cm²Less than 5 per piece is judged as “particularly good”, 5 or more and less than 20 is judged as “good”, and 20 or more is judged as “bad”.
(4) Antistatic property
A high resistivity meter (Hiresta-UP) manufactured by Mitsubishi Chemical Corporation was used to measure the surface resistivity (Ω) of the film. The antistatic property was evaluated based on the surface resistivity. Surface resistivity is 1.0 × 10¹¹Less than Ω is “particularly good”, 1.0 × 10¹¹1.0 × 10 or more¹²Less than Ω is “good”, 1.0 × 10¹²The above is judged as “bad”.
(5) Pencil hardness (hard coat property)
Using a pencil hardness tester manufactured by Toyo Seiki Co., Ltd., the pencil hardness of the film was measured according to JIS K5400. It is determined that the pencil hardness H is “good” and HB is “bad”.
(6) Persistence of antistatic effect
After leaving the hard coat film in a dryer at 90 ° C. for 250 hours, an oily material appears on the hard coat surface, and if the bleed-out of the conductive agent is confirmed, “Yes”, if not, “No” It was. In the case of “present”, it is determined as “bad”.
The evaluation results are shown in Table 1 below.

In Table 1, Examples 1 to 5 containing a compatibilizer compared with Comparative Example 1 containing no compatibilizer at all have extremely high agglomerates in the paint, appearance uniformity of the coated product, and transparency (haze). It turns out that it is excellent. In addition, when Comparative Example 2 using a low molecular surfactant as a conductive agent and Examples 1 to 5 are compared, the use of the conductive polymer of the present invention maintains the antistatic effect even at extremely high temperatures and for a long time. A remarkable effect is seen. When the curable resin is pentaerythritol tetraacrylate, the conductive polymer is an acrylate copolymer containing a quaternary ammonium base, and the compatibilizer is hydroxyethyl acrylate, the compatibilizer contains 5% or more of the solid content of the coating. In this case, it can be seen that the cohesion is remarkably improved. Moreover, it turns out that there exists a suitable range with the usage-amount with respect to curable resin of a conductive polymer. In the case of this example, the blending of 10 to 40% was appropriate. Within this range, when a hard coat layer is formed by applying a coating composition, a hard coat film excellent in high transparency, antistatic properties, uniformity, scratch resistance, and chemical resistance can be obtained. I understand.

Claims (7)

An ultraviolet ray or radiation curable resin having at least three (meth) acryloyl groups, a conductive polymer, and a compatibilizing agent having one or two (meth) acryloyl groups and at least one hydroxyl group. Or the coating composition which does not need to contain this compatibilizing agent, when a radiation curable resin has a hydroxyl group in the molecule | numerator. The conductive polymer has a molecular weight of 2 × 10 ⁴ to 50 × 10 ⁴ , and is any one of a polyether, a quaternary ammonium base-containing polymer, a sulfonic acid-containing polymer, or a polymer charge transfer-type binder polymer. The solubilizer is an ultraviolet ray or radiation-reactive monomer or an oligomer having a molecular weight of 1 × 10 ³ or less, and the ratio of the compatibilizer or its equivalent to the solid content at the time of curing of the coating composition is 5% by weight or more. The coating composition according to claim 1. The coating composition according to claim 2, wherein the conductive polymer is a quaternary ammonium base-containing polymer. The coating composition according to claim 3, wherein the quaternary ammonium base-containing polymer is a quaternary ammonium base-containing (meth) acrylate copolymer. The coating composition according to any one of claims 1 to 4, wherein a ratio of the conductive polymer to a solid content at the time of curing of the coating composition is 10 to 40% by weight. Charge which has the electroconductive hard-coat layer formed by apply | coating the coating composition as described in any one of Claims 1-5 to at least one surface of a thermoplastic resin film, and irradiating with an ultraviolet-ray or a radiation and hardening. Prevent hard coat film. The antistatic hard coat film according to claim 6, wherein the thermoplastic resin film is triacetyl cellulose.