JP4519421B2 - Resin composition and vehicle lamp lens using the same - Google Patents
Resin composition and vehicle lamp lens using the same Download PDFInfo
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Description
【０００１】
【発明の属する技術分野】
本発明は、車輌用ランプレンズとして用いるテールランプ、ストップランプに関する。
【０００２】
【従来の技術】
透明性、耐候性に優れるアクリル樹脂は、車輌用ランプレンズに使用されているが、ウインドウオッシャー液、ワックスリムーバー等に含まれる有機溶剤により溶剤クラックが生じやすい問題がある。この耐溶剤性を向上させる為、レンズ材料の改良が検討されてきており、高分子量メタクリレート樹脂を使用する方法（特許文献１）、アクリル系グラフトゴムを使用する方法（特許文献２）等提案されている。しかし高分子量にすることでは成形流動性が低下するため成形加工性に劣り、グラフトゴムを用いる場合には透明性が低下しアクリル樹脂本来の特性を損なうという問題があり、この成形加工性、透明性は本発明者が出願中の特定の共重合体を使用する方法（特許文献３）で改善できるが２種以上の有機溶剤に対する耐溶剤クラック性はまだ不十分である。
【０００３】
【特許文献１】
特公平５−８２００１号公報
【特許文献２】
特開平７−２８２６０２号公報
【特許文献３】
特願２００２−１０３０４７号公報
【０００４】
【発明が解決しようとする課題】
本発明の課題は、アクリル樹脂本来の特性である透明性、耐候性を損なうことなく２種類以上の有機溶剤に対する耐溶剤クラック性にすぐれしかも流動性が高く成形加工性にすぐれた車輌用ランプレンズを提供する事にある。
【０００５】
【課題を解決するための手段】
前記課題を解決するため本発明者らは鋭意検討の結果、メタクリル酸メチルを主成分とした特定の共重合体からなる樹脂組成物をもちいれば達成できる事を見出し本発明の完成に至った。
すなわち本発明は、
（１） 下記（Ａ）に示されるモノマー組成を共重合してなる共重合体（Ａ）１０〜３０重量部と、下記（Ｂ）に示されるモノマー組成を共重合してなる共重合体（Ｂ）７０〜９０重量部からなる樹脂組成物であって、全体の重量平均分子量が１５〜２７万であり、共重合体（Ａ）の重量平均分子量が２〜８万であることを特徴とする樹脂組成物。
共重合体（Ａ）のモノマー組成；
メタクリル酸メチル ５０〜８９ｗｔ％
アルキル基の炭素数が１〜４であるアルキルアクリレート １０〜４０ｗｔ％
スチレン １〜１０ｗｔ％
共重合体（Ｂ）のモノマー組成；
メタクリル酸メチル ９３〜９９ｗｔ％
アルキル基の炭素数が１〜４であるアルキルアクリレート ０．５〜３ｗｔ％
スチレン ０．５〜４ｗｔ％
【０００６】
（２） 該樹脂組成物が、成形流動性指標（ＳＦ）２７０以上である（１）記載の樹脂組成物。
但し、成形流動性指標（ＳＦ）＝断面形状１０×２（ｍｍ）のスパイラルフロー金型で、温度２５０℃圧力７５メガパスカルで射出成形した成形体先端までの流れ距離（ｍｍ）。
（３） 該樹脂組成物が、耐溶剤性指標（Ｋ１）と（Ｋ２）がいずれも４００を超える（１）〜（２）のいずれか一項に記載の樹脂組成物。
但し、耐溶剤性指標（Ｋ１）＝負荷曲げ応力４０メガパスカルでのエタノール塗布時の破断時間（秒）、（Ｋ２）＝負荷曲げ応力６０メガパスカルでのワックスリムーバー塗布時の破断時間（秒）
【０００７】
（４） 該樹脂組成物が、耐候性指標（Ｗ）が２．０未満である（１）〜（３）のいずれか一項に記載の樹脂組成物。
但し、耐候性指標（Ｗ）＝サンシヤインウエザーメーター１０００時間照射後の黄変度と未照射品黄変度との差。
（５） （１）〜（４）のいずれか一項に記載の樹脂組成物を射出成形して得られる車輌用ランプレンズ。
に関する。
以下に本発明を詳細に説明する。
【０００８】
本発明で用いられる共重合体（Ａ）とは、メタクリル酸メチルとアルキル基炭素数が１〜４のアルキルアクリレートとスチレンとで構成されるモノマー混合液をラジカル重合したゲルパーミュレーションクロマトグラフイー（以下ＧＰＣと略記）で測定した重量平均分子量（ＧＰＣ法でのＰＭＭＡ換算見掛け重量平均分子量）２〜８万のアクリル系３元共重合体である。
モノマー混合液中でのメタクリル酸メチルの使用量は５０〜８９ｗｔ％の範囲であることが必要であり、５０ｗｔ％未満の場合は透明性、耐候性のいずれかが損なわれやすく好ましくない、８９ｗｔ％を超える場合には流動性の改善効果が小さく好ましくない、モノマー混合液中でのアルキル基炭素数１〜４のアルキルアクリレートの使用量は１０〜４０ｗｔ％であることが必要である、１０ｗｔ％未満の場合は成形流動性の改良効果が小さく好ましくない、４０ｗｔ％を超える場合には耐熱変形性が損なわれる。
【０００９】
上記アルキル基炭素数が１〜４のアルキルアクリレートとはアクリル酸メチル、アクリル酸エチル、アクリル酸ｎ−ブチルでありこれらは必要に応じて単独または２種以上を用いても良い、モノマー混合液中でのスチレンの使用量は１〜１０ｗｔ％であることが必要である、１ｗｔ％未満の場合は透明性が損なわれ好ましくない、１０ｗｔ％を超える場合には耐候性が損なわれる、また通常法でラジカル重合した該共重合体の重量平均分子量は２〜８万の範囲である必要がある、２万未満の場合は耐溶剤性に劣り改善されない、８万を超える場合には成形流動性が実質改良されない、より好ましい範囲は３〜７万である。
【００１０】
本発明で用いられる共重合体（Ｂ）とはメタクリル酸メチルとアルキル基炭素数が１〜４であるアルキルアクリレートとスチレンとで構成されるモノマー混合液でラジカル重合した共重合体であり、モノマー混合液でのメタクリル酸メチルの使用量は９３〜９９ｗｔ％であることが必要であり、９３ｗｔ％未満の場合は透明性、耐候性、耐熱変形性の少なく共ひとつが損なわれやすく好ましくない、９９ｗｔ％を超える場合には熱分解しやすく射出成形体に外観不良が発生しやすくなり好ましくない。
【００１１】
モノマー混合液でのアルキル基炭素数１〜４のアルキルアクリレートの使用量は０．５〜３ｗｔ％であることが必要であり、０．５ｗｔ％未満の場合は耐熱分解性を損ね好ましくない、３ｗｔ％超える場合には耐熱変形性に劣り好ましくない、モノマー混合液でのスチレンの使用量は０．５〜４ｗｔ％であることが必要であり、０．５％未満では透明性に劣り、４ｗｔ％を超える場合には耐候性、透明性に劣り好ましくない。
【００１２】
本発明の樹脂組成物とは上記の共重合体（Ａ）と共重合体（Ｂ）との混合物であって全体の重量平均分子量が１５〜２７万である、樹脂組成物中での使用量は共重合体（Ａ）１０〜３０重量部と共重合体（Ｂ）７０〜９０重量部である（Ａ＋Ｂの合計は１００重量部）、共重合体（Ａ）の使用量を１０〜３０重量部とする理由は、成形流動性を付与する為である、使用量が１０重量部未満の場合は成形流動性向上効果が小さい、３０重量部を超える場合には耐熱変形性に劣る。
【００１３】
一方共重合体（Ｂ）の使用量を７０〜９０重量部とする理由は、耐溶剤性・機械強度特性を付与する為である、使用量が７０重量部未満の場合は耐溶剤性改善効果が期待できず、さらに機械強度特性にも劣る、９０重量部を超える場合には成形流動性は実質改善されない、又該樹脂組成物全体の重量平均分子量は１５〜２７万の範囲内にあることが必要である、１５万未満の場合は脆弱化して機械強度特性に劣り且つ耐溶剤性は改善されない、２７万を超える場合には成形流動性に劣り射出成形困難となる、範囲外ではいずれも本発明課題は達成できない、より好ましい範囲は１７〜２５万である。
【００１４】
本発明樹脂組成物の耐熱変形性は熱変形温度（ＨＤＴ）９０℃以上であり、ランプレンズ用材料として９０〜１００℃のアクリル樹脂が広く使用されており要求特性を維持している。９０℃未満では高温・多湿となる環境では成形体が変形しランプレンズとして使用できない場合もある。この特性を損ねること無く維持する為には、樹脂組成物中でのアルキルアクリレート単位比率はアクリル酸メチルの場合には１０ｗｔ％未満、アクリル酸エチルの場合には８ｗｔ％未満、アクリル酸ｎブチルの場合には６ｗｔ％未満である事が好ましい。
【００１５】
本発明車輌用ランプレンズでの耐候性は耐候性指標Ｗ（サンシャインウェザーメーター１０００時間照射前後での黄変度差）が２．０未満であり、アクリル樹脂本来の重要特性を維持している。２．０を超える場合には耐候性に劣る為車体視認装置として当然問題となる。この重要特性を損ねること無く実質維持する為には樹脂組成物中でのメチルメタクリレート単位比率は８１ｗｔ以上である事が好ましい。
【００１６】
本発明の車輌用ランプレンズは上記の樹脂組成物を造粒混合した樹脂ペレットを射出成形する事により得られる、造粒混合法、射出成形法については特に限定されず公知のものが使用でき、射出成形温度は２２０〜２７０℃の範囲である。本発明の共重合体（Ａ）、（Ｂ）の製造法は公知の懸濁重合、溶液重合、塊状重合等の重合方法を応用して製造でき特に限定されない、必要に応じて共重合体（Ａ）と（Ｂ）は連続して２段重合してもよいし、別個に重合してもよい、また共重合体（Ａ）を（Ｂ）のモノマー組成液に溶解して重合してもよい。本発明の車両用ランプレンズには必要に応じて公知の色剤、紫外線吸収剤・酸化防止剤等の安定剤、各種添加剤を使用してもよい。
【００１７】
【発明の実施の形態】
以下に実施例、比較例、を用いて本発明をさらに具体的に説明する。
実施例に使用される部はすべて重量部であり、％はすべて重量％である。以下の実施例において物性測定は以下の方法で行った。
１．耐溶剤性
射出成形板から１２．７×１２７×３ｍｍの試験片を切り出しし、８０℃で３０分アニールしデシケーター中で放置冷却した、片持ち梁法を適用し、試験片の一端を固定し、そこから５ｃｍはなれた位置を支点とし、さらに支点から５ｃｍはなれた他端へ荷重を加え、該支点上の試験片上面中央に縦５ｍｍ横５ｍｍの濾紙をのせ、濾紙上へエタノールをマイクロシリンジで滴下塗布し、温度２５℃、相対湿度５０％で、負荷曲げ応力４０ＭＰＡでの破断時間（秒）を測定し耐溶剤性の指標（Ｋ１）とした、同様操作でワツクスリムーバー（ユシロ化学社製ＣＰＣ）を滴下塗布し、負荷曲げ表面応力６０ＭＰＡでの破断時間（秒）を耐溶剤性の指標（Ｋ２）とした。
【００１８】
２．成形流動性
螺旋渦巻き状の射出成形品先端までの流動距離を下記条件で求めた。
成形機 東芝機械製ＩＳ−１００ＥＮ、金型 成形品断面（２×１０ｍｍ短板）の螺旋渦巻き型、成形温度２５０℃、金型温度５５℃、成形圧力７５メガパスカル、射出速度最大で連続成形し９１〜１００ショツト成形品の流動先端までの流れ距離（ｍｍ）を測定し算術平均値を成形流動指標（ＳＦ）とした。
【００１９】
３．重合体・レンズ用樹脂の重量平均分子量
ゲルパーミエーシヨンクロマトグラフイー法（ＧＰＣ）で下記条件で求めた装置東ソー（株）製ＨＬＣ−８１２０＋ＳＣ−８０２０、カラム東ソーＴＳＫスーパーＨＨ−Ｍ（２本）スーパーＨ２５００（１本）直列、検出器ＲＩ、溶媒ＴＨＦ、流量０．３ｍｌ／分、試料１０ｍｇ／２０ｍｌＴＨＦ液を１０μｌ装置注入、
単分散ＰＭＭＡ（ジーエルサイエンス製）を標準試料とした検量線で重量平均分子量を求めた。
【００２０】
４．引張り強度
ＡＳＴＭ規格Ｄ６３８に準拠、試験片厚さ１／８インチ
５．ヘーズ
ＪＩＳ規格Ｋ７１３６に準拠、試験片厚さ１／８インチ
６.黄変度
ＪＩＳ規格Ｋ７１０５に準拠、測色条件（Ｂ）、試験片厚さ３ｍｍ
【００２１】
７．耐候性
サンシヤインウェザーメーター法で下記条件で求めた。
試験装置 スガ試験機（株）製ＷＥ−ＳＵＮ−ＤＣ、ＢＰ温度６３℃、水１２分／乾燥６０分サイクルで１０００時間連続照射（アークカーボンは５０時間で交換）後の黄変度を測定し、２３℃の恒温室内暗所デシケーター保存した未照射品の黄変度を測定し、両者の黄変度差の絶対値を耐候性指標（Ｗ）とした。
８．熱変形温度（以下ＨＤＴと略記する）
ＡＳＴＭ規格D６４８に準拠、試験片厚さ１／４インチ
【００２２】
【実施例１】
６０リットルの重合器に、メタクリル酸メチル１１．３４部、アクリル酸ｎブチル２．１部、スチレン０．５６部、ラウロイルパーオキサイド０．１５部、ｎ−オクチルメルカプタン０．１４部、脱イオン水２００部、三リン酸カルシウム０．５部、炭酸カルシウム０．３部、ラウリル硫酸ナトリウム０．００３部を投入し攪拌混合した、反応温度８０℃で１９０分懸濁重合し、重合転化率９８％、重量平均分子量４万の共重合体（Ａ）を得た、１０分後にＭＭＡ８２．９０４部、アクリル酸ｎブチル０．５１６部、スチレン２．５８部、ラウロイルパーオキサイド０．２２部、ｎ−オクチルメルカプタン０．１１部からなる共重合体（Ｂ）のモノマー配合液を追加投入し、攪拌機の回転数を増して１５分間攪拌混合した。
【００２３】
反応温度８０℃でさらに１３０分懸濁重合し、続いて１００℃で６０分熟成し重合反応を実質終了、次に５０℃まで冷却して鉱酸を投入し、洗浄脱水乾燥処理しビーズ状ポリマー（共重合体ＢとＡの混合物）を得た、上記のビーズ状ポリマーをベント付押出機に供給し、温度２４５〜２５５℃ベント真空圧力７００〜７５０ｍｍＨｇで押出して重量平均分子量１９万の樹脂ペレットを得た、このペレットを名機製作所製Ｍ−７０で射出成形し、成形温度２５０℃で２００×２００×３ｍｍの平板成形品を得た。物性は耐溶剤性指標（Ｋ１）１６００秒（Ｋ２）２０００秒、成形流動性指標（ＳＦ）３２０ｍｍ、ＨＤＴ９８℃、引張り強度７５０Ｋｇ／ｃｍ2、へーズ０．３％、耐候性指標（Ｗ）０．５であった。
以下の実施例比較例での共重合体Ａ、Ｂの重量平均分子量はすべてn−オクチルメルカプタンの使用量を変更して調整した。
【００２４】
【実施例２】
共重合体（Ｂ）の重量平均分子量を変更した以外は実施例１と同様の条件操作で成形品を得た、樹脂ペレットは重量平均分子量２３万であり、物性は耐溶剤性指標（Ｋ１）２１００秒（Ｋ２）２５００秒、成形流動性指標（ＳＦ）２８０ｍｍ、ＨＤＴ９８℃、引張り強度７６０Ｋｇ／ｃｍ2、へーズ０．３％耐候性指標（Ｗ）０．６であった。
【００２５】
【実施例３】
共重合体（Ｂ）の重量平均分子量を変更した以外は実施例１と同様の条件操作で成形品を得た、樹脂ペレットは重量平均分子量１７万であり、物性は耐溶剤性指標（Ｋ１）１２００秒（Ｋ２）１４００秒、成形流動性指標（ＳＦ）３３０ｍｍ、ＨＤＴ９８℃、引張り強度７２０Ｋｇ／ｃｍ2、へーズ０．３％、耐候性指標（Ｗ）０．６であった。
【００２６】
【実施例４】
共重合体Ａの重量平均分子量を変更した以外は実施例１と同様の条件操作で成形品を得た、共重合体（Ａ）は重量平均分子量３万であり、樹脂ペレットは重量平均分子量１８万であった、物性は耐溶剤性指標（Ｋ１）１４００秒（Ｋ２）１５００秒、成形流動性指標（ＳＦ）３３０ｍｍ、ＨＤＴ９８℃、引張り強度７３０Ｋｇ／ｃｍ2、へーズ０．３％、耐候性指標（Ｗ）０．６であった。
【００２７】
【実施例５】
共重合体Ａの重量平均分子量を変更した以外は実施例１と同様の条件操作で成形品を得た。共重合体（Ａ）は重量平均分子量６万であり、樹脂ペレットは重量平均分子量１９万であった、物性は耐溶剤性指標（Ｋ１）１９００秒（Ｋ２）２０００秒、成形流動性指標（ＳＦ）３１０ｍｍ、ＨＤＴ９８℃、引張り強度７３０Ｋｇ／ｃｍ2、へーズ０．３％、耐候性指標（Ｗ）０．６であった。
【００２８】
【実施例６】
単量体混合液の反応機投入部数を初期２５部追加７５部に変更した以外は実施例１と同様の条件操作で成形品を得た、共重合体（Ａ）は重合転化率９８％、重量平均分子量４万であり、樹脂ペレットは重量平均分子量１６万であった、物性は耐溶剤性指標（Ｋ１）７００秒（Ｋ２）８５０秒、成形流動性指標（ＳＦ）３７０ｍｍ、ＨＤＴ９３℃、引張り強度６８０Ｋｇ／ｃｍ2、へーズ０．４％耐候性指標（Ｗ）０．６であった。
【００２９】
【実施例７】
メタクリル酸メチル１５．２部、アクリル酸メチル２部、アクリル酸ｎブチル２部、スチレン０．８部を最初に投入し、２１０分後にメタクリル酸メチル７７．１２部、アクリル酸ｎブチル０．４８部、スチレン２．４部を追加投入に変更した以外は実施例１と同様の条件操作で成形品を得た、共重合体（Ａ）は重合転化率９８％、重量平均分子量４万であり、樹脂ペレットは重量平均分子量２０万であった、物性は耐溶剤性指標（Ｋ１）１２００秒（Ｋ２）１８００秒、成形流動性指標（ＳＦ）３６０ｍｍ、ＨＤＴ９５℃、引張り強度７２０Ｋｇ／ｃｍ2、へーズ０．３％、耐候性指標（Ｗ）０．６であった。
【００３０】
【実施例８】
メタクリル酸メチル１２部、アクリル酸メチル７部、スチレン１部を最初に投入し、２１０分後にメタクリル酸メチル７５．２部、アクリル酸メチル１．６部、スチレン３．２部を追加投入に変更した以外は実施例１と同様の条件操作で成形品を得た、共重合体（Ａ）は重合転化率９８％、重量平均分子量４万であり、樹脂ペレットは重量平均分子量２２万であった、物性は耐溶剤性指標（Ｋ１）１４００秒（Ｋ２）１６００秒、成形流動性指標（ＳＦ）３８０ｍｍ、ＨＤＴ９３℃、引張り強度７２０Ｋｇ／ｃｍ2、へーズ０．３％、耐候性指標（Ｗ）０．９であった。
【００３１】
【実施例９】
メタクリル酸メチル１３．６部、アクリル酸nブチル５部、スチレン部１．４部を最初に投入し、２４０分後にメタクリル酸メチル７５．５２部、アクリル酸メチル０．４８部、スチレン４部を追加投入に変更した以外は実施例１と同様の条件操作で成形品を得た。共重合体（Ａ）は重量平均分子量４万であり、樹脂ペレットは重量平均分子量２３万であった、物性は耐溶剤性指標（Ｋ１）１５００秒（Ｋ２）１４００秒、成形流動性指標（ＳＦ）３９０ｍｍ、ＨＤＴ９１℃、引張り強度７００Ｋｇ／ｃｍ2、へーズ０．３％、耐候性指標（Ｗ）１、１であった。
【００３２】
【比較例１】
単量体混合液の反応機投入部数を初期３５部追加６５部に変更した以外は実施例１と同様の条件操作で成形品を得た、樹脂ペレットは重量平均分子量１８万であった、物性は耐溶剤性指標（Ｋ１）２００秒（Ｋ２）１４０秒、成形流動性指標（ＳＦ）３４０ｍｍ、ＨＤＴ９２℃、引張り強度６００Ｋｇ／ｃｍ2、へーズ０．７％、耐候性指標（Ｗ）０．７であった。
【００３３】
【比較例２】
単量体混合液の反応機投入部数を初期５部追加９５部に変更した以外は実施例１と同様の条件操作で成形品を得た、樹脂ペレットは重量平均分子量１８万であった、物性は耐溶剤性指標（Ｋ１）１７００秒（Ｋ２）２２００秒、成形流動性指標（ＳＦ）２６０ｍｍ、ＨＤＴ９９℃、引張り強度７５０Ｋｇ／ｃｍ2、へーズ０．３％、耐候性指標（Ｗ）０．５であった。
【００３４】
【比較例３】
共重合体（Ａ）の重量平均分子量を変更した以外は実施例１と同様の条件操作で成形品を得た、共重合体（Ａ）は重量平均分子量１万であり、樹脂ペレットは重量平均分子量１８万であった、物性は耐溶剤性指標（Ｋ１）１５０秒（Ｋ２）２００秒、成形流動性指標（ＳＦ）３４０ｍｍ、ＨＤＴ９８℃、引張り強度６２０Ｋｇ／ｃｍ2、へーズ０．３％、耐候性指標（Ｗ）０．５であった。
【００３５】
【比較例４】
共重合体（Ａ）の重量平均分子量を変更した以外は実施例１と同様の条件操作で成形品を得た、共重合体（Ａ）は重量平均分子量９万であり、樹脂ペレットは重量平均分子量１９万であった、物性は耐溶剤性指標（Ｋ１）１８００秒（Ｋ２）２１００秒、成形流動性指標（ＳＦ）２４０ｍｍ、ＨＤＴ９８℃、引張り強度７６０Ｋｇ／ｃｍ2、へーズ０．３％、耐候性指標（Ｗ）０．５であった。
【００３６】
【比較例５】
共重合体（Ｂ）の重量平均分子量を変更した以外は実施例１と同様の条件操作で成形品を得た、樹脂ペレットは重量平均分子量１３万であった、物性は耐溶剤性指標（Ｋ１）９０秒（Ｋ２）１５０秒、成形流動性指標（ＳＦ）３６０ｍｍ、ＨＤＴ９８℃、引張り強度５５０Ｋｇ／ｃｍ2、へーズ０．３％、耐候性指標（Ｗ）０．６であった。
【００３７】
【比較例６】
共重合体（Ｂ）の重量平均分子量を変更した以外は実施例１と同様の条件操作で成形品を得た、樹脂ペレットは重量平均分子量２８万であった、物性は耐溶剤性指標（Ｋ１）３５００秒（Ｋ２）４２００秒、成形流動性指標（ＳＦ）１４０ｍｍ、ＨＤＴ９８℃、引張り強度７５０Ｋｇ／ｃｍ2、へーズ０．３％、耐候性指標（Ｗ）０．６であった。
【００３８】
【比較例７】
メタクリル酸メチル１３．０２部、アクリル酸ｎブチル０．７部、スチレン０．２８部を最初に投入と変更した以外は実施例１と同様の条件操作で成形品を得た、共重合体（Ａ）は重合転化率９８％、重量平均分子量４万であり、樹脂ペレットは重量平均分子量１９万であった、物性は耐溶剤性指標（Ｋ１）３５０秒（Ｋ２）８５０秒、成形流動性指標（ＳＦ）２５０ｍｍ、ＨＤＴ９９℃、引張り強度７３０Ｋｇ／ｃｍ2、へーズ０．５％、耐候性指標（Ｗ）０．５であった。
【００３９】
【比較例８】
メタクリル酸メチル２４．５部、アクリル酸メチル８．７５部、スチレン１、７５部を最初に投入し、１４０分後にメタクリル酸メチル６１．１部、アクリル酸メチル１．３部、スチレン２．６部を追加投入に変更した以外は実施例１と同様の条件操作で成形品を得た、共重合体（Ａ）は重合転化率９８％、重量平均分子量４万であり、樹脂ペレットは重量平均分子量２２万であった、物性は耐溶剤性指標（Ｋ１）１５０秒（Ｋ２）１００秒、成形流動性指標（ＳＦ）４００ｍｍ、ＨＤＴ８９℃、引張り強度７１０Ｋｇ／ｃｍ2、へーズ０．４％、耐候性指標（Ｗ）０．９であった。
【００４０】
【比較例９】
メタクリル酸メチル７部、アクリル酸メチル７部を最初に投入し、１３０分後にメタクリル酸メチル８２．５６部、アクリル酸メチル３．４４部を追加投入に変更した以外は実施例１と同様の条件操作で成形品を得た、共重合体（Ａ）は重合転化率９８％、重量平均分子量４万であり、樹脂ペレットは重量平均分子量１９万であった、物性は耐溶剤性指標（Ｋ１）５０秒（Ｋ２）３００秒、成形流動性指標（ＳＦ）３４０ｍｍ、ＨＤＴ８９℃、引張り強度７００Ｋｇ／ｃｍ2、へーズ１．８％、耐候性指標（Ｗ）０．４であった。
【００４１】
【比較例１０】
メタクリル酸メチル６．０２部、アクリル酸ｎブチル６．３部、スチレン１．６８部を最初に投入し、２３０分後にメタクリル酸メチル７６．８８４部、アクリル酸メチル０．５１６部、スチレン８．６部を追加投入に変更した以外は実施例１と同様の条件操作で成形品を得た、共重合体（Ａ）は重合転化率９８％、重量平均分子量４万であり、樹脂ペレットは重量平均分子量１９万であった、物性は耐溶剤性指標（Ｋ１）１５０秒（Ｋ２）２００秒、成形流動性指標（ＳＦ）３５０ｍｍ、ＨＤＴ８９℃、引張り強度６３０Ｋｇ／ｃｍ2、へーズ０．８％、耐候性指標（Ｗ）２．６であった。
【００４２】
【比較例１１】
メタクリル酸メチル９４．６６部、アクリル酸メチル０．５２部、アクリル酸ｎブチル１．６８部、スチレン３．１４部を全量一括投入した以外は実施例１と同様の操作で成形品を得た、樹脂ペレットは重量平均分子量１９万であった、物性は耐溶剤性指標（Ｋ１）１５００秒（Ｋ２）１９００秒、成形流動性指標（ＳＦ）２１０ｍｍ、ＨＤＴ９８℃、引張り強度７５０Ｋｇ／ｃｍ2、へーズ０．３％、耐候性指標（Ｗ）０．６であった。
【００４３】
【比較例１２】
メタクリル酸メチル８９．２部、アクリル酸メチル６．６部、スチレン４．２部を全量一括投入した以外は実施例１と同様の操作で成形品を得た、樹脂ペレットは重量平均分子量２２万であった、物性は耐溶剤性指標（Ｋ１）１３００秒（Ｋ２）１４００秒、成形流動性指標（ＳＦ）１９０ｍｍ、ＨＤＴ９３℃、引張り強度７２０Ｋｇ／ｃｍ2、へーズ０．３％、耐候性指標（Ｗ）０．９であった。
【００４４】
【比較例１３】
旭化成製デルペット８０ＮＢ（重量平均分子量１８万）を用いて同様の成形品を得た、物性は耐溶剤性指標（Ｋ１）４５０秒（Ｋ２）１５００秒、成形流動性指標（ＳＦ）２００ｍｍ、ＨＤＴ９５℃、引張り強度７５０Ｋｇ／ｃｍ2、へーズ０．３％、耐候性指標（Ｗ）０．４であった。
【００４５】
【比較例１４】
旭化成製デルペット８０Ｎ（重量平均分子量１０万）を用いて同様の成形品を得た、物性は耐溶剤性指標（Ｋ１）１０秒（Ｋ２）５０秒、成形流動性指標（ＳＦ）３３０ｍｍ、ＨＤＴ１００℃、引張り強度７２０Ｋｇ／ｃｍ2、へーズ０．３％、耐候性指標（Ｗ）０．４であった。
【００４６】
【表１】
実施例１〜９で用いた共重合体（Ａ）のモノマー組成及び重合機投入量、重合転化率、重量平均分子量をまとめて記載した。
【００４８】
【表２】
実施例１〜９で用いた共重合体（Ｂ）のモノマー組成及び重合機投入量をまとめて記載した。
【００５０】
【表３】
比較例１〜１２で用いた共重合体（Ａ）のモノマー組成及び重合機投入量、重合転化率、重量平均分子量をまとめて記載した。
【００５２】
【表４】
比較例１〜１２で用いた共重合体（Ｂ）のモノマー組成及び重合機投入量をまとめて記載した。
【００５４】
【表５】
実施例１〜９の樹脂物性をまとめて記載した。
【００５６】
【表６】
比較例１〜１４の樹脂物性をまとめて記載した。
【００５８】
【発明の効果】
本発明は、アクリル樹脂本来の特性である透明性、耐候性を損なうことなく２種類以上の有機溶剤に対する耐溶剤クラック性にすぐれしかも流動性が高く成形加工性にすぐれた車輌用ランプレンズを提供する事ができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a tail lamp and a stop lamp used as a vehicle lamp lens.
[0002]
[Prior art]
Acrylic resins having excellent transparency and weather resistance are used in vehicle lamp lenses, but there is a problem that solvent cracks are likely to occur due to organic solvents contained in window washer liquid, wax remover and the like. In order to improve this solvent resistance, improvement of the lens material has been studied, and a method using a high molecular weight methacrylate resin (Patent Document 1), a method using an acrylic graft rubber (Patent Document 2), etc. have been proposed. ing. However, when the molecular weight is increased, the molding fluidity is lowered, so that the molding processability is inferior. When the graft rubber is used, there is a problem that the transparency is lowered and the original properties of the acrylic resin are impaired. The property can be improved by the method using the specific copolymer pending by the present inventor (Patent Document 3), but the solvent crack resistance against two or more organic solvents is still insufficient.
[0003]
[Patent Document 1]
Japanese Patent Publication No. 5-82001 [Patent Document 2]
JP-A-7-282602 [Patent Document 3]
Japanese Patent Application No. 2002-103047
[Problems to be solved by the invention]
An object of the present invention is to provide a vehicle lamp lens with excellent solvent cracking resistance to two or more organic solvents, high fluidity and excellent moldability without impairing transparency and weather resistance, which are inherent characteristics of acrylic resin. Is to provide.
[0005]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present inventors have intensively studied and found that this can be achieved by using a resin composition comprising a specific copolymer mainly composed of methyl methacrylate, and the present invention has been completed. .
That is, the present invention
(1) 10-30 parts by weight of a copolymer (A) obtained by copolymerizing the monomer composition shown in the following (A) and a copolymer obtained by copolymerizing the monomer composition shown in the following (B) ( B) A resin composition comprising 70 to 90 parts by weight, wherein the total weight average molecular weight is 15 to 270,000, and the weight average molecular weight of the copolymer (A) is 2 to 80,000. Resin composition.
Monomer composition of copolymer (A);
Methyl methacrylate 50-89wt%
Alkyl acrylate having 1 to 4 carbon atoms of alkyl group 10 to 40 wt%
Styrene 1-10wt%
Monomer composition of copolymer (B);
Methyl methacrylate 93-99wt%
Alkyl acrylate having 1 to 4 carbon atoms of alkyl group 0.5 to 3 wt%
Styrene 0.5-4wt%
[0006]
(2) the resin composition is molded fluidity index (SF) 270 or more (1) Symbol placement of the resin composition.
However, molding fluidity index (SF) = flow distance (mm) to the tip of a molded body injection-molded at a temperature of 250 ° C. and a pressure of 75 megapascals with a spiral flow mold having a cross-sectional shape of 10 × 2 (mm).
( 3 ) The resin composition according to any one of (1) to ( 2), wherein the solvent resistance index (K1) and (K2) both exceed 400.
However, solvent resistance index (K1) = rupture time (seconds) when applying ethanol at a load bending stress of 40 megapascals (K2) = rupture time (seconds) when applying a wax remover at a load bending stress of 60 megapascals
[0007]
( 4 ) The resin composition according to any one of (1) to (3), wherein the resin composition has a weather resistance index (W) of less than 2.0.
However, the weather resistance index (W) = the difference between the yellowing degree after 1000 hours irradiation of the sunshade weather meter and the yellowing degree of the unirradiated product.
( 5 ) A vehicle lamp lens obtained by injection molding the resin composition according to any one of (1) to (4) .
About.
The present invention is described in detail below.
[0008]
The copolymer (A) used in the present invention is a gel permeation chromatography obtained by radical polymerization of a monomer mixture composed of methyl methacrylate, alkyl acrylate having 1 to 4 alkyl groups and styrene. It is an acrylic terpolymer having a weight average molecular weight (hereinafter, abbreviated as GPC) (PMMA equivalent apparent weight average molecular weight by GPC method) of 20,000 to 80,000.
The amount of methyl methacrylate used in the monomer mixture needs to be in the range of 50 to 89 wt%, and if it is less than 50 wt%, either transparency or weather resistance is easily impaired, which is not preferable, 89 wt% When the amount exceeds 1, the fluidity improving effect is small and is not preferable. The amount of the alkyl acrylate having 1 to 4 alkyl groups in the monomer mixture is required to be 10 to 40 wt%, less than 10 wt% In this case, the effect of improving the molding fluidity is small and undesirable, and when it exceeds 40 wt%, the heat distortion resistance is impaired.
[0009]
The alkyl acrylate having 1 to 4 carbon atoms in the alkyl group is methyl acrylate, ethyl acrylate, or n-butyl acrylate, and these may be used alone or in combination of two or more as required. It is necessary that the amount of styrene used is 1 to 10% by weight. If it is less than 1% by weight, the transparency is impaired, and if it exceeds 10% by weight, the weather resistance is impaired. The weight average molecular weight of the radical-polymerized copolymer needs to be in the range of 20,000 to 80,000. If it is less than 20,000, the solvent resistance is inferior and is not improved. The more preferable range which is not improved is 3 to 70,000.
[0010]
The copolymer (B) used in the present invention is a copolymer obtained by radical polymerization with a monomer mixed solution composed of methyl methacrylate, alkyl acrylate having 1 to 4 alkyl groups and C 1, and monomer. The amount of methyl methacrylate used in the mixed solution needs to be 93 to 99 wt%, and in the case of less than 93 wt%, transparency, weather resistance, and heat deformation are few, and it is not preferable that one is easily damaged. If it exceeds 50%, thermal decomposition tends to occur, and an appearance defect tends to occur in the injection molded product, which is not preferable.
[0011]
The amount of the alkyl acrylate having 1 to 4 alkyl groups in the monomer mixture is required to be 0.5 to 3 wt%. If it is less than 0.5 wt%, the thermal decomposition resistance is impaired, which is not preferable. When the amount exceeds 50%, the heat distortion resistance is inferior, which is not preferable. The amount of styrene used in the monomer mixture is required to be 0.5 to 4 wt%, and when it is less than 0.5%, the transparency is inferior and 4 wt%. If it exceeds 1, the weather resistance and transparency are inferior.
[0012]
The resin composition of the present invention is a mixture of the above copolymer (A) and copolymer (B), and the total weight average molecular weight is 15 to 270,000, and the amount used in the resin composition Is 10 to 30 parts by weight of copolymer (A) and 70 to 90 parts by weight of copolymer (B) (the total of A + B is 100 parts by weight), and the amount of copolymer (A) used is 10 to 30 parts by weight. The reason for making it part is to impart molding fluidity. When the amount used is less than 10 parts by weight, the effect of improving the molding fluidity is small, and when it exceeds 30 parts by weight, the heat distortion resistance is poor.
[0013]
On the other hand, the reason why the amount of the copolymer (B) used is 70 to 90 parts by weight is to impart solvent resistance and mechanical strength characteristics. When the amount used is less than 70 parts by weight, the solvent resistance improving effect is achieved. The molding fluidity is not substantially improved when it exceeds 90 parts by weight, and the weight average molecular weight of the entire resin composition is in the range of 15 to 270,000. If it is less than 150,000, it becomes brittle and inferior in mechanical strength and solvent resistance is not improved. If it exceeds 270,000, it becomes inferior in molding fluidity and difficult to injection mold. The more preferable range which cannot achieve the subject of the present invention is 17 to 250,000.
[0014]
The resin composition of the present invention has a heat distortion temperature (HDT) of 90 ° C. or higher, and an acrylic resin of 90 to 100 ° C. is widely used as a lamp lens material and maintains the required characteristics. If it is less than 90 ° C., the molded body may be deformed in an environment where the temperature and humidity are high, and the lamp lens may not be used. In order to maintain this characteristic without impairing, the alkyl acrylate unit ratio in the resin composition is less than 10 wt% in the case of methyl acrylate, less than 8 wt% in the case of ethyl acrylate, and n butyl acrylate. In some cases, it is preferably less than 6 wt%.
[0015]
The weather resistance of the vehicle lamp lens according to the present invention is such that the weather resistance index W (difference in yellowing before and after irradiation for 1000 hours by the sunshine weather meter) is less than 2.0, and the original important characteristics of the acrylic resin are maintained. If it exceeds 2.0, the weather resistance is inferior. In order to substantially maintain this important characteristic without impairing it, the methyl methacrylate unit ratio in the resin composition is preferably 81 wt.
[0016]
The vehicle lamp lens of the present invention is obtained by injection molding resin pellets obtained by granulating and mixing the above resin composition, granulation mixing method, injection molding method is not particularly limited, and known ones can be used, The injection molding temperature is in the range of 220-270 ° C. The method for producing the copolymers (A) and (B) of the present invention can be produced by applying a known polymerization method such as suspension polymerization, solution polymerization, bulk polymerization and the like, and is not particularly limited. A) and (B) may be continuously polymerized in two stages, or may be polymerized separately, or the copolymer (A) may be polymerized by dissolving it in the monomer composition solution of (B). Good. In the vehicle lamp lens of the present invention, known colorants, stabilizers such as ultraviolet absorbers and antioxidants, and various additives may be used as necessary.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.
All parts used in the examples are parts by weight and all percentages are percentages by weight. In the following examples, physical properties were measured by the following methods.
1. A test piece of 12.7 × 127 × 3 mm was cut out from the solvent-resistant injection-molded plate, annealed at 80 ° C. for 30 minutes, and allowed to cool in a desiccator. The cantilever method was applied, and one end of the test piece was fixed. A load is applied to the other end 5 cm away from the fulcrum at a position 5 cm away from the fulcrum, and a 5 mm vertical 5 mm filter paper is placed on the center of the upper surface of the test piece on the fulcrum. The same procedure was used to apply a drop remover (manufactured by Yushiro Chemical Co., Ltd.) by measuring the rupture time (seconds) under a load bending stress of 40 MPa at a temperature of 25 ° C. and a relative humidity of 50%. CPC) was applied dropwise, and the rupture time (seconds) at a load bending surface stress of 60 MPa was used as an index of solvent resistance (K2).
[0018]
2. Molding fluidity The flow distance to the tip of the spiral spiral injection molded product was determined under the following conditions.
Molding machine Toshiba Machine IS-100EN, molds Helical spiral mold with a cross section of molded product (2 x 10mm short plate), molding temperature 250 ° C, mold temperature 55 ° C, molding pressure 75 megapascal, continuous injection molding at maximum injection speed The flow distance (mm) to the flow front of the 91-100 shot molded product was measured, and the arithmetic average value was used as the molding flow index (SF).
[0019]
3. HLC-8120 + SC-8020 manufactured by Tosoh Co., Ltd., column Tosoh TSK Super HH-M (2 pieces) obtained under the following conditions by weight average molecular weight gel permeation chromatography (GPC) of polymer / lens resin Super H2500 (1) in series, detector RI, solvent THF, flow rate 0.3 ml / min, sample 10 mg / 20 ml THF solution injected into 10 μl device,
The weight average molecular weight was determined by a calibration curve using monodispersed PMMA (manufactured by GL Science) as a standard sample.
[0020]
4). 5. Tensile strength in accordance with ASTM standard D638, specimen thickness 1/8 inch. Haze JIS standard K7136 compliant, specimen thickness 1/8 inch 6. Yellowing degree JIS standard K7105 compliant, colorimetric conditions (B), specimen thickness 3 mm
[0021]
7). It calculated | required on condition of the following by the weather-resistant sansiya weather meter method.
Test device WE-SUN-DC manufactured by Suga Test Instruments Co., Ltd. BP temperature 63 ° C, water 12 minutes / drying 60 minutes cycle, 1000 hours continuous irradiation (arc carbon is exchanged in 50 hours), the degree of yellowing is measured The yellowing degree of an unirradiated product stored in a dark room desiccator at 23 ° C. was measured, and the absolute value of the difference in yellowing degree was used as a weather resistance index (W).
8). Heat distortion temperature (hereinafter abbreviated as HDT)
Conforms to ASTM standard D648, specimen thickness is 1/4 inch. [0022]
[Example 1]
In a 60 liter polymerization vessel, 11.34 parts methyl methacrylate, 2.1 parts nbutyl acrylate, 0.56 parts styrene, 0.15 parts lauroyl peroxide, 0.14 parts n-octyl mercaptan, deionized water 200 parts, 0.5 part of calcium triphosphate, 0.3 part of calcium carbonate and 0.003 part of sodium lauryl sulfate were added and mixed with stirring. Suspension polymerization was carried out at a reaction temperature of 80 ° C. for 190 minutes, polymerization conversion 98%, weight 10 minutes after obtaining copolymer (A) having an average molecular weight of 40,000 82.904 parts of MMA, 0.516 parts of n-butyl acrylate, 2.58 parts of styrene, 0.22 parts of lauroyl peroxide, n-octyl mercaptan An additional 0.11 part of the monomer blend solution of copolymer (B) was added, and the number of revolutions of the stirrer was increased, followed by stirring and mixing for 15 minutes.
[0023]
Suspension polymerization at a reaction temperature of 80 ° C for an additional 130 minutes, followed by aging at 100 ° C for 60 minutes to complete the polymerization reaction, then cooling to 50 ° C, adding mineral acid, washing, dehydrating and drying, and then bead polymer The above-mentioned bead polymer obtained (mixture of copolymers B and A) was supplied to an extruder equipped with a vent and extruded at a temperature of 245 to 255 ° C. under a vacuum pressure of 700 to 750 mmHg, and a resin pellet having a weight average molecular weight of 190,000 This pellet was injection molded with M-70 manufactured by Meiki Seisakusho to obtain a flat plate molded product of 200 × 200 × 3 mm at a molding temperature of 250 ° C. The physical properties are solvent resistance index (K1) 1600 seconds (K2) 2000 seconds, molding fluidity index (SF) 320 mm, HDT 98 ° C., tensile strength 750 kg / cm 2 , haze 0.3%, weather resistance index (W) 0 .5.
The weight average molecular weights of the copolymers A and B in the following comparative examples were all adjusted by changing the amount of n-octyl mercaptan used.
[0024]
[Example 2]
Except for changing the weight average molecular weight of the copolymer (B), a molded product was obtained by the same operation as in Example 1. The resin pellet has a weight average molecular weight of 230,000, and the physical properties are solvent resistance index (K1). They were 2100 seconds (K2) 2500 seconds, molding fluidity index (SF) 280 mm, HDT 98 ° C., tensile strength 760 Kg / cm 2 , and haze 0.3% weather resistance index (W) 0.6.
[0025]
[Example 3]
Except for changing the weight average molecular weight of the copolymer (B), a molded product was obtained by the same operation as in Example 1. The resin pellet had a weight average molecular weight of 170,000, and the physical properties were solvent resistance index (K1). It was 1200 seconds (K2), 1400 seconds, molding fluidity index (SF) 330 mm, HDT 98 ° C., tensile strength 720 Kg / cm 2 , haze 0.3%, and weather resistance index (W) 0.6.
[0026]
[Example 4]
Except for changing the weight average molecular weight of the copolymer A, a molded product was obtained by the same operation as in Example 1. The copolymer (A) has a weight average molecular weight of 30,000, and the resin pellet has a weight average molecular weight of 18 The physical properties were solvent resistance index (K1) 1400 seconds (K2) 1500 seconds, molding fluidity index (SF) 330 mm, HDT 98 ° C., tensile strength 730 Kg / cm 2 , haze 0.3%, weather resistance The index (W) was 0.6.
[0027]
[Example 5]
Except for changing the weight average molecular weight of the copolymer A, a molded product was obtained by the same operation as in Example 1. The copolymer (A) had a weight average molecular weight of 60,000, the resin pellets had a weight average molecular weight of 190,000, physical properties were solvent resistance index (K1) 1900 seconds (K2) 2000 seconds, molding fluidity index (SF ) 310 mm, HDT 98 ° C., tensile strength 730 kg / cm 2 , haze 0.3%, weatherability index (W) 0.6.
[0028]
[Example 6]
A molded product was obtained by the same condition operation as in Example 1 except that the number of reactors added to the monomer mixture was changed to 25 parts initial and 75 parts added, and the copolymer (A) had a polymerization conversion rate of 98%, The weight average molecular weight was 40,000, the resin pellets had a weight average molecular weight of 160,000, the physical properties were solvent resistance index (K1) 700 seconds (K2) 850 seconds, molding fluidity index (SF) 370 mm, HDT 93 ° C., tensile The strength was 680 kg / cm 2 , and the haze was 0.4% and the weather resistance index (W) was 0.6.
[0029]
[Example 7]
First, 15.2 parts of methyl methacrylate, 2 parts of methyl acrylate, 2 parts of n-butyl acrylate, and 0.8 parts of styrene are charged, and after 210 minutes, 77.12 parts of methyl methacrylate and n-butyl acrylate 0.48 The copolymer (A) had a polymerization conversion rate of 98% and a weight average molecular weight of 40,000, except that the parts and styrene 2.4 parts were changed to the additional charge. The resin pellets had a weight average molecular weight of 200,000, the physical properties were solvent resistance index (K1) 1200 seconds (K2) 1800 seconds, molding fluidity index (SF) 360 mm, HDT 95 ° C., tensile strength 720 Kg / cm 2 , Of 0.3% and weather resistance index (W) of 0.6.
[0030]
[Example 8]
First, 12 parts of methyl methacrylate, 7 parts of methyl acrylate, and 1 part of styrene are added, and after 210 minutes, 75.2 parts of methyl methacrylate, 1.6 parts of methyl acrylate, and 3.2 parts of styrene are added. The copolymer (A) had a polymerization conversion rate of 98% and a weight average molecular weight of 40,000, and the resin pellets had a weight average molecular weight of 220,000. The physical properties are solvent resistance index (K1) 1400 seconds (K2) 1600 seconds, molding fluidity index (SF) 380 mm, HDT 93 ° C., tensile strength 720 Kg / cm 2 , haze 0.3%, weather resistance index (W) 0.9.
[0031]
[Example 9]
First, 13.6 parts of methyl methacrylate, 5 parts of n-butyl acrylate, and 1.4 parts of styrene are added. After 240 minutes, 75.52 parts of methyl methacrylate, 0.48 parts of methyl acrylate, and 4 parts of styrene are added. A molded product was obtained by the same condition operation as in Example 1 except that it was changed to additional charging. The copolymer (A) had a weight average molecular weight of 40,000, the resin pellet had a weight average molecular weight of 230,000, the physical properties were solvent resistance index (K1) 1500 seconds (K2) 1400 seconds, molding fluidity index (SF 390 mm, HDT 91 ° C., tensile strength 700 Kg / cm 2 , haze 0.3%, weather resistance index (W) 1, 1
[0032]
[Comparative Example 1]
A molded product was obtained by the same condition operation as in Example 1 except that the number of reactors charged in the monomer mixture was changed to the initial 35 parts and 65 parts, and the resin pellets had a weight average molecular weight of 180,000. Solvent resistance index (K1) 200 seconds (K2) 140 seconds, molding fluidity index (SF) 340 mm, HDT 92 ° C., tensile strength 600 Kg / cm 2 , haze 0.7%, weather resistance index (W) 0. 7.
[0033]
[Comparative Example 2]
A molded product was obtained by the same condition operation as in Example 1 except that the number of parts added to the reactor of the monomer mixture was changed to the initial 5 parts and 95 parts, and the resin pellet had a weight average molecular weight of 180,000. Is solvent resistance index (K1) 1700 seconds (K2) 2200 seconds, molding fluidity index (SF) 260 mm, HDT 99 ° C., tensile strength 750 kg / cm 2 , haze 0.3%, weather resistance index (W) 0. It was 5.
[0034]
[Comparative Example 3]
Except for changing the weight average molecular weight of the copolymer (A), a molded product was obtained by the same operation as in Example 1. The copolymer (A) has a weight average molecular weight of 10,000, and the resin pellets have a weight average. The molecular weight was 180,000, the physical properties were solvent resistance index (K1) 150 seconds (K2) 200 seconds, molding fluidity index (SF) 340 mm, HDT 98 ° C., tensile strength 620 Kg / cm 2 , haze 0.3%, The weather resistance index (W) was 0.5.
[0035]
[Comparative Example 4]
Except for changing the weight average molecular weight of the copolymer (A), a molded product was obtained by the same operation as in Example 1. The copolymer (A) has a weight average molecular weight of 90,000, and the resin pellets have a weight average. The molecular weight was 190,000, the physical properties were solvent resistance index (K1) 1800 seconds (K2) 2100 seconds, molding fluidity index (SF) 240 mm, HDT 98 ° C., tensile strength 760 Kg / cm 2 , haze 0.3%, The weather resistance index (W) was 0.5.
[0036]
[Comparative Example 5]
Except that the weight average molecular weight of the copolymer (B) was changed, a molded product was obtained by the same operation as in Example 1. The resin pellet had a weight average molecular weight of 130,000, the physical properties were solvent resistance index (K1 ) 90 seconds (K2) 150 seconds, molding fluidity index (SF) 360 mm, HDT 98 ° C., tensile strength 550 Kg / cm 2 , haze 0.3%, weather resistance index (W) 0.6.
[0037]
[Comparative Example 6]
Except for changing the weight average molecular weight of the copolymer (B), a molded product was obtained by the same operation as in Example 1. The resin pellets had a weight average molecular weight of 280,000. The physical properties were solvent resistance index (K1 ) 3500 seconds (K2) 4200 seconds, molding fluidity index (SF) 140 mm, HDT 98 ° C., tensile strength 750 Kg / cm 2 , haze 0.3%, weather resistance index (W) 0.6.
[0038]
[Comparative Example 7]
A copolymer obtained by molding under the same conditions as in Example 1 except that 13.02 parts of methyl methacrylate, 0.7 part of n-butyl acrylate, and 0.28 part of styrene were initially charged and changed. A) has a polymerization conversion of 98%, a weight average molecular weight of 40,000, a resin pellet has a weight average molecular weight of 190,000, physical properties are solvent resistance index (K1) 350 seconds (K2) 850 seconds, molding fluidity index (SF) 250 mm, HDT 99 ° C., tensile strength 730 kg / cm 2 , haze 0.5%, weather resistance index (W) 0.5.
[0039]
[Comparative Example 8]
First, 24.5 parts of methyl methacrylate, 8.75 parts of methyl acrylate, and 1 and 75 parts of styrene were charged, and after 140 minutes, 61.1 parts of methyl methacrylate, 1.3 parts of methyl acrylate, and 2.6 of styrene A molded product was obtained by the same operation as in Example 1 except that the part was changed to additional charging. The copolymer (A) had a polymerization conversion of 98%, a weight average molecular weight of 40,000, and the resin pellets had a weight average. The molecular weight was 220,000, the physical properties were solvent resistance index (K1) 150 seconds (K2) 100 seconds, molding fluidity index (SF) 400 mm, HDT 89 ° C., tensile strength 710 Kg / cm 2 , haze 0.4%, The weather resistance index (W) was 0.9.
[0040]
[Comparative Example 9]
The same conditions as in Example 1 except that 7 parts of methyl methacrylate and 7 parts of methyl acrylate were added first, and after 82 minutes 82.56 parts of methyl methacrylate and 3.44 parts of methyl acrylate were changed to additional addition. The molded product was obtained by the operation. The copolymer (A) had a polymerization conversion of 98%, a weight average molecular weight of 40,000, the resin pellet had a weight average molecular weight of 190,000, and the physical properties were solvent resistance index (K1). The molding fluidity index (SF) was 340 mm, HDT 89 ° C., tensile strength 700 Kg / cm 2 , haze 1.8%, weather resistance index (W) 0.4.
[0041]
[Comparative Example 10]
First, 6.02 parts of methyl methacrylate, 6.3 parts of n-butyl acrylate, and 1.68 parts of styrene were charged, and after 230 minutes, methyl methacrylate, 7.6.884 parts, methyl acrylate, 0.516 parts, styrene, 8. A molded product was obtained by the same operation as in Example 1 except that 6 parts were changed to additional charging. The copolymer (A) had a polymerization conversion of 98%, a weight average molecular weight of 40,000, and the resin pellets were The average molecular weight was 190,000, the physical properties were solvent resistance index (K1) 150 seconds (K2) 200 seconds, molding fluidity index (SF) 350 mm, HDT 89 ° C., tensile strength 630 Kg / cm 2 , haze 0.8% The weather resistance index (W) was 2.6.
[0042]
[Comparative Example 11]
A molded product was obtained in the same manner as in Example 1 except that 94.66 parts of methyl methacrylate, 0.52 parts of methyl acrylate, 1.68 parts of n-butyl acrylate, and 3.14 parts of styrene were all added at once. The resin pellets had a weight average molecular weight of 190,000, the physical properties were solvent resistance index (K1) 1500 seconds (K2) 1900 seconds, molding fluidity index (SF) 210 mm, HDT 98 ° C., tensile strength 750 Kg / cm 2 , Of 0.3% and weather resistance index (W) of 0.6.
[0043]
[Comparative Example 12]
A molded product was obtained in the same manner as in Example 1 except that 89.2 parts of methyl methacrylate, 6.6 parts of methyl acrylate, and 4.2 parts of styrene were all added at once. The resin pellet had a weight average molecular weight of 220,000. The physical properties were solvent resistance index (K1) 1300 seconds (K2) 1400 seconds, molding fluidity index (SF) 190 mm, HDT 93 ° C., tensile strength 720 Kg / cm 2 , haze 0.3%, weather resistance index (W) It was 0.9.
[0044]
[Comparative Example 13]
A similar molded product was obtained using Asahi Kasei Delpet 80NB (weight average molecular weight 180,000). The physical properties were solvent resistance index (K1) 450 seconds (K2) 1500 seconds, molding fluidity index (SF) 200 mm, HDT95. The tensile strength was 750 kg / cm 2 , the haze was 0.3%, and the weather resistance index (W) was 0.4.
[0045]
[Comparative Example 14]
A similar molded product was obtained using Asahi Kasei Delpet 80N (weight average molecular weight 100,000). Physical properties were solvent resistance index (K1) 10 seconds (K2) 50 seconds, molding fluidity index (SF) 330 mm, HDT100 The tensile strength was 720 kg / cm 2 , the haze was 0.3%, and the weather resistance index (W) was 0.4.
[0046]
[Table 1]
The monomer composition of the copolymer (A) used in Examples 1 to 9, the input amount of the polymerization machine, the polymerization conversion rate, and the weight average molecular weight are collectively described.
[0048]
[Table 2]
The monomer composition of the copolymer (B) used in Examples 1 to 9 and the input amount of the polymerization machine are collectively described.
[0050]
[Table 3]
The monomer composition of the copolymer (A) used in Comparative Examples 1 to 12, the input amount of the polymerization machine, the polymerization conversion rate, and the weight average molecular weight are collectively described.
[0052]
[Table 4]
The monomer composition of the copolymer (B) used in Comparative Examples 1 to 12 and the input amount of the polymerization machine are collectively described.
[0054]
[Table 5]
The resin physical properties of Examples 1 to 9 are collectively described.
[0056]
[Table 6]
The resin physical properties of Comparative Examples 1 to 14 were collectively described.
[0058]
【The invention's effect】
The present invention provides a vehicle lamp lens with excellent solvent cracking resistance to two or more organic solvents, high fluidity and excellent moldability without impairing transparency and weather resistance, which are the inherent characteristics of acrylic resin. I can do it.
Claims (5)
共重合体（Ａ）のモノマー組成；
メタクリル酸メチル ５０〜８９ｗｔ％
アルキル基の炭素数が１〜４であるアルキルアクリレート １０〜４０ｗｔ％
スチレン １〜１０ｗｔ％
共重合体（Ｂ）のモノマー組成；
メタクリル酸メチル ９３〜９９ｗｔ％
アルキル基の炭素数が１〜４であるアルキルアクリレート ０．５〜３ｗｔ％
スチレン ０．５〜４ｗｔ％10 to 30 parts by weight of a copolymer (A) obtained by copolymerizing the monomer composition shown in the following (A), and a copolymer (B) 70 obtained by copolymerizing the monomer composition shown in the following (B) A resin composition comprising ˜90 parts by weight, wherein the total weight average molecular weight is from 150 to 270,000, and the weight average molecular weight of the copolymer (A) is from 2 to 80,000. object.
Monomer composition of copolymer (A);
Methyl methacrylate 50-89wt%
Alkyl acrylate having 1 to 4 carbon atoms of alkyl group 10 to 40 wt%
Styrene 1-10wt%
Monomer composition of copolymer (B);
Methyl methacrylate 93-99wt%
Alkyl acrylate having 1 to 4 carbon atoms of alkyl group 0.5 to 3 wt%
Styrene 0.5-4wt%
但し、成形流動性指標（ＳＦ）＝断面形状１０×２（ｍｍ）のスパイラルフロー金型で、温度２５０℃圧力７５メガパスカルで射出成形した成形体先端までの流れ距離（ｍｍ）。The resin composition, mold flow index (SF) 270 over the which claim 1 Symbol placement of the resin composition.
However, molding fluidity index (SF) = flow distance (mm) to the tip of a molded body injection-molded at a temperature of 250 ° C. and a pressure of 75 megapascals with a spiral flow mold having a cross-sectional shape of 10 × 2 (mm).
但し、耐溶剤性指標（Ｋ１）＝ 負荷曲げ応力４０メガパスカルでのエタノール塗布時の破断時間（秒）、（Ｋ２）＝負荷曲げ応力６０メガパスカルでのワックスリムーバー塗布時の破断時間（秒）The resin composition according to any one of claims 1 and 2, wherein the resin composition has a solvent resistance index (K1) and (K2) both exceeding 400.
However, solvent resistance index (K1) = break time (sec) when applying ethanol with a load bending stress of 40 megapascals (K2) = break time (sec) when applying a wax remover with a load bending stress of 60 megapascals
但し、耐候性指標（Ｗ）＝サンシヤインウエザーメーター１０００時間照射後の黄変度と未照射品黄変度との差。The resin composition according to any one of claims 1 to 3, wherein the resin composition has a weather resistance index (W) of less than 2.0.
However, the weather resistance index (W) = the difference between the yellowing degree after 1000 hours irradiation of the sunshade weather meter and the yellowing degree of the unirradiated product.
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| JP5026671B2 (en) * | 2005-01-14 | 2012-09-12 | 三菱レイヨン株式会社 | Acrylic resin composition and vehicle member containing the composition |
| EP1953177B2 (en) | 2005-11-24 | 2019-06-19 | Asahi Kasei Kabushiki Kaisha | Methacrylic resin and method for producing same |
| JP2008038068A (en) * | 2006-08-09 | 2008-02-21 | Soken Chem & Eng Co Ltd | Binder resin for near-infrared-absorbing film |
| JP5131956B2 (en) * | 2007-01-16 | 2013-01-30 | 旭化成ケミカルズ株式会社 | Thickener and method for producing the same |
| JP5247314B2 (en) * | 2008-09-03 | 2013-07-24 | 三菱レイヨン株式会社 | Methacrylic resin composition |
| JP5674325B2 (en) * | 2010-02-18 | 2015-02-25 | 旭化成ケミカルズ株式会社 | Molded product obtained using methacrylic resin composition |
| JP5621836B2 (en) * | 2012-12-13 | 2014-11-12 | 三菱レイヨン株式会社 | Methacrylic resin composition |
| JP5672321B2 (en) * | 2013-03-07 | 2015-02-18 | 三菱レイヨン株式会社 | Methacrylic resin composition |
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| JPS58101140A (en) * | 1981-12-10 | 1983-06-16 | Mitsubishi Rayon Co Ltd | Acrylic resin composition having improved flow properties |
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