JP2004067789A

JP2004067789A - Method for manufacturing cast molded article of impact-resistant methacrylate resin

Info

Publication number: JP2004067789A
Application number: JP2002227032A
Authority: JP
Inventors: Masashi Mori; 森　正士
Original assignee: Sumitomo Chemical Co Ltd
Current assignee: Sumitomo Chemical Co Ltd
Priority date: 2002-08-05
Filing date: 2002-08-05
Publication date: 2004-03-04
Also published as: CN1326937C; TWI285661B; CN1488670A; KR20040014252A; TW200406459A

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method which makes it possible to manufacture a cast molded article of an impact-resistant methacrylate resin, having sufficient impact resistance, a low residual monomer content, and higher transparency. <P>SOLUTION: A composition is used which contains a monomer comprising mainly methyl methacrylate, a methacrylate resin comprising mainly methyl methacrylate units, (multilayer) elastic material particles, a first organic peroxide comprising a monofunctional organic peroxide having a 10-hr half-life temperature of 60°C or lower, a second organic peroxide comprising a monofunctional organic peroxide having a 10-hr half-life temperature of above 60°C to 80°C, and a third organic peroxide comprising a monofunctional organic peroxide having a 10-hr half-life temperature of above 80°C. The composition is polymerized by keeping it in a polymerization cell at a temperature, for example, lower than the 10-hr half-life temperature of the first organic peroxide by at least 10°C, and then raising the temperature to a temperature higher than the 10-hr half-life temperature of the third organic peroxide by at least 10°C. The obtained molded article is excellent in transparency and the like. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、耐衝撃性メタクリル樹脂キャスト成形体の製造方法に関する。
【０００２】
【従来の技術】
耐衝撃性メタクリル樹脂キャスト成形体は、弾性体粒子を含有しキャスト重合法によって得られるメタクリル樹脂成形体であって、例えば屋内の間仕切り板、道路の遮音板などとして有用である。かかる耐衝撃性メタクリル樹脂キャスト成形体の製造方法として特開平８−１５１４９８号公報には、メタクリル酸メチルを主成分とする単量体、メタクリル酸メチル単位を主成分とするメタクリル樹脂、弾性体粒子および重合開始剤を含む組成物を重合セル内で重合させる方法が開示されており、重合開始剤として有機過酸化物、アゾ化合物などを用いることができる旨も開示されている。かかる耐衝撃性メタクリル樹脂キャスト成形体には、十分な耐衝撃性を有し、用いた単量体が残存せず、透明であることが求められている。
【０００３】
しかし、かかる従来の製造方法で得られた耐衝撃性メタクリル樹脂キャスト成形体は、残存する単量体が比較的多く、また十分に透明であるとは言えなかった。
【０００４】
【発明が解決しようとする課題】
そこで、本発明者は、透明性のより高い耐衝撃性メタクリル樹脂キャスト成形体を製造し得る方法を開発すべく鋭意検討した結果、重合開始剤として１０時間半減温度が異なる複数の単官能有機過酸化物を用いることで、残存する単量体が少なく、十分な耐衝撃性を有していて、透明性がより高い耐衝撃性メタクリル樹脂キャスト成形体を製造し得ることを見出し、本発明に至った。
【０００５】
【課題を解決するための手段】
すなわち本発明は、メタクリル酸メチルを主成分とする単量体、メタクリル酸メチル単位を主成分とするメタクリル樹脂、弾性体粒子、以下の第一有機過酸化物、以下の第二有機過酸化物および以下の第三有機過酸化物を含む組成物を重合セル内で重合させることを特徴とする耐衝撃性メタクリル樹脂キャスト成形体の製造方法を提供するものである。
【０００６】
第一有機過酸化物：１０時間半減温度が６０℃以下である単官能有機過酸化物
第二有機過酸化物：１０時間半減温度が６０℃を超え８０℃以下である単官能有機過酸化物
第三有機過酸化物：１０時間半減温度が８０℃を越える単官能有機過酸化物
【０００７】
【発明の実施の形態】
本発明の製造方法で用いられる単量体は、メタクリル酸メチルを主成分とするものであり、メタクリル酸メチルを単独であってもよいし、メタクリル酸メチルと共重合し得る単量体を含む混合物であってもよい。メタクリル酸メチルと共重合し得る単量体としては、例えばアクリル酸メチル、アクリル酸エチル、アクリル酸２−エチルヘキシルなどのアクリル酸エステル類、メタクリル酸エチル、メタクリル酸ｎ−ブチル、メタクリル酸イソブチル、メタクリル酸２−エチルヘキシルなどのメタクリル酸エステル類、メタクリル酸、無水マレイン酸、スチレン、シクロヘキシルマレイミド、アクリロニトリルなどが挙げられる。なお、ここでメタクリル酸エステル類には、メタクリル酸メチルは含まれない。これらの共重合し得る単量体は、それぞれ１種であってもよいし、２種以上であってもよい。共重合し得る単量体を含む混合物である場合、かかる混合物におけるメタクリル酸メチルの含有量は質量分率で５０％以上である。メタクリル酸メチルを主成分とする単量体を構成するメタクリル酸メチルや、メタクリル酸メチルと共重合し得る単量体は、２量体、３量体などのオリゴマーとなっていてもよい。
【０００８】
メタクリル樹脂は、メタクリル酸メチル単位を主成分とする重合体である。メタクリル樹脂は、メタクリル酸メチル単位単独からなるメタクリル酸メチルのホモポリマーであってもよいし、メタクリル酸メチルと共重合可能な単量体との共重合体であってもよい。メタクリル酸メチルと共重合可能な単量体としては、メタクリル酸メチルを主成分とする単量体において上記したと同様の単量体が挙げられる。メタクリル樹脂が共重合体である場合に、メタクリル酸メチル単位の含有量は質量分率で５０％以上である。メタクリル樹脂は、粘度平均分子量が通常１００００以上３０００００以下程度である。
【０００９】
弾性体粒子は、弾性体単独からなる単層の弾性体粒子であってもよい。また、弾性体からなる核と、その周囲に形成されたメタクリル樹脂層とからなる２層構造の弾性体粒子、メタクリル樹脂かなる核と、その周囲に形成された弾性体からなる中間層と、中間層の周囲に形成されたメタクリル樹脂からなる外層とからなる３層構造の弾性体粒子などの多層構造弾性体粒子であってもよい。かかる弾性体粒子の粒子径は通常０．１μｍ以上１μｍ以下、好ましくは０．２μｍ以上０．８μｍ以下程度である。粒子径が０．１μｍ未満であると耐衝撃性に劣る傾向にあり、また１μｍを超えると透明性が低下する傾向にあり、好ましくない。透明性により優れた耐衝撃性メタクリル樹脂キャスト成形体が得られる点で、多層構造弾性体粒子、特には３層構造弾性体粒子が好ましく用いられる。
【００１０】
なお、かかる弾性体粒子は、メタクリル樹脂に分散された状態で、例えば「スミペックスＨＴ０１Ｘ」（住友化学工業（株）より販売）、「オログラスＤＲ」（住化ハース（有）より販売）などの耐衝撃性メタクリル樹脂として市販されている。
【００１１】
メタクリル樹脂および弾性体粒子の使用量比は、質量比で通常３：７〜７：３程度である。また、メタクリル樹脂および弾性体粒子の合計使用量は、単量体、メタクリル樹脂および弾性体粒子の合計使用量を１００質量部として、通常１０質量部以上４０質量部以下程度である。１０質量部未満であると耐衝撃性が不十分となり、４０質量部を超えると、組成物の粘度が高くなって、重合セルへの充填が困難となる傾向にある。
【００１２】
本発明の製造方法では、重合開始剤として上記第一有機過酸化物、第二有機過酸化物および第三有機過酸化物を用いる。有機過酸化物は、分子内に式（１）
【化１】

で示される残基を有する有機化合物である。有機過酸化物は、この残基（１）が分解してラジカルを生ずる。１０時間半減温度（Ｔ）とは、有機過酸化物を単独で加熱したときに、１０時間後に有機過酸化物の半数が分解する温度であり、具体的にはベンゼンなどの不活性溶媒に溶解した溶液を一定温度に加熱して、分解生成物の生成量の時間変化から求めた一次反応のアーレニウス式に基づき算出される温度である。
【００１３】
本発明の製造方法で用いられる有機過酸化物は、単官能有機過酸化物である。ここで単官能有機過酸化物とは、分子内に式（１）で示される残基を１個有する有機過酸化物である。例えばジ−ｔ−ブチルパーオキシトリメチルアジペートなどのように、２個以上の残基（１）を分子内に有する多官能有機過酸化物では、得られる成形体に残存する単量体が多くなる傾向にある。
【００１４】
かかる第一有機過酸化物としては、例えばｔ−ヘキシルパーオキシネオデカネート（Ｔ＝４５℃）、ジメトキシブチルパーオキシジカーボネート（Ｔ＝４６℃）、ｔ−ブチルパーオキシネオデカノエート（Ｔ＝４６℃）、ｔ−ヘキシルパーオキシピバレート（Ｔ＝５３℃）、ｔ−ブチルパーオキシピバレート（Ｔ＝５５℃）、３，５，５−トリメチルヘキサノイルパーオキサイド（Ｔ＝５９℃）などが挙げられ、取扱いが容易な点で、１０時間半減温度が４０℃以上、さらには５０℃以上の有機過酸化物が好ましく用いられる。
【００１５】
第二有機過酸化物としては、例えばオクタノイルパーオキサイド（Ｔ＝６２℃）、ラウロイルパーオキサイド（Ｔ＝６２℃）、ステアロイルパーオキサイド（Ｔ＝６２℃）、１，１，３，３−テトラメチルブチルパーオキシ２−エチルヘキサノエート（６６℃）、サクシニックパーオキサイド（Ｔ＝６６℃）、１−シクロヘキシル−１−メチルエチルパーオキシ２−エチルヘキサノエート（Ｔ＝６８℃）、ｔ−ヘキシルパーオキシ２−エチルヘキサノエート（Ｔ＝７０℃）、ｔ−ブチルパーオキシ２−エチルヘキサノエート（Ｔ＝７２℃）、ｔ−ブチルパーオキシイソブチレート（Ｔ＝７８℃）などが挙げられる。
【００１６】
第三有機過酸化物としては、例えばｔ−ヘキシルパーオキシイソプロピルモノカーボネート（Ｔ＝９５℃）、ｔ−ブチルパーオキシマレイン酸（Ｔ＝９６℃）、ｔ−ブチルパーオキシ−３，５，５−トリメチルヘキサノエート（Ｔ＝９７℃）、ｔ−ブチルパーオキシラウレート（Ｔ＝９８℃）、ｔ−ブチルパーオキシイソプロピルカーボネート（Ｔ＝９９℃）、ｔ−ブチルパーオキシ２−エチルヘキシルモノカーボネート（Ｔ＝９９℃）、ｔ−ヘキシルパーオキシベンゾエート（Ｔ＝９９℃）、ｔ−ブチルパーオキシアセテート（Ｔ＝１０２℃）、ｔ−ブチルパーオキシベンゾエート（ｔ＝１０４℃）、ジクミルパーオキサイド（Ｔ＝１１９℃）、ｔ−ブチルクミルパーオキサイド（Ｔ＝１２０℃）などが挙げられ、重合時の最高温度を比較的低くできる点で、１０時間半減温度が１１０℃以下の有機過酸化物が好ましく用いられる。
【００１７】
第一有機過酸化物の１０時間半減温度（Ｔ_１）と第二有機過酸化物の１０時間半減温度（Ｔ_２）との差（ΔＴ_１２）は、より透明性に優れた耐衝撃性メタクリル樹脂キャスト成形体が得られる点で、１０℃以上、さらには１３℃以上であることが好ましく、通常は３０℃以下である。また、第二有機過酸化物の１０時間半減温度（Ｔ_２）と、第三有機過酸化物の１０時間半減温度（Ｔ_３）との差（ΔＴ_２３）は、より透明性に優れた耐衝撃性メタクリル樹脂キャスト成形体が得られる点で、１０℃以上、さらには１８℃以上であることが好ましく、通常は３５℃以下である。
【００１８】
第一有機過酸化物の使用量と第二有機過酸化物の使用量との比は、物質量比で３：７〜７：３程度、好ましくは４：６〜６：４程度であり、第一有機過酸化物および第二有機過酸化物の合計使用量と第三有機過酸化物の使用量との比は、物質量比で３：７〜７：３程度、好ましくは４：６〜６：４程度であり、第一有機過酸化物、第二有機過酸化物および第三有機過酸化物の合計使用量はメタクリル酸メチルを主成分とする単量体の使用量１００質量部当たり０．０５質量部以上０．５質量部以下程度である。
【００１９】
第一有機過酸化物、第二有機過酸化物および第三有機過酸化物は通常不活性溶媒で希釈された状態で使用される。ここで、不活性溶媒はこれら有機過酸化物の種類に応じて適宜選択されるが、例えばナフサ、重合ガソリンなどの飽和脂肪族炭化水素溶媒、ベンゼン、トルエンなどの炭化水素溶媒、アセトン、クメン、ジフェニルエタン、酢酸エチルなどが挙げられる。
【００２０】
かかる単量体、メタクリル樹脂、弾性体粒子、第一有機過酸化物、第二有機過酸化物および第三有機過酸化物を含む組成物は、目的とする耐衝撃性メタクリル樹脂キャスト成形体の用途に応じて、酸化防止剤、紫外線吸収剤、離型剤、染料などの添加剤を含有していてもよい。
【００２１】
本発明の製造方法では、かかる組成物を重合セル内で重合させる。本発明の製造方法では、かかる組成物を重合セル内で重合させるので、十分な耐衝撃性を有し、単量体の含有量が少なく、透明性に優れた耐衝撃性メタクリル樹脂キャスト成形体を得ることができる。
【００２２】
重合セルとしては通常のキャスト重合法に用いられる重合セルを用いることができ、例えば目的の耐衝撃性メタクリル樹脂キャスト成形体が板状である場合には、互いに平行に配置された２枚の基板から構成されるバッチ式セル、互いに平行に配置された２枚の連続ベルトからなる連続式セルなどが挙げられる。
【００２３】
バッチ式セルを用いる場合、基板としては、例えばガラス基板、金属基板を用いることができる。これら２枚の基板は、軟質シール材を介して配置され、２枚の基板とこの軟質シール材とで囲まれた領域で組成物が重合する。基板間の距離は、目的の板状の成形体の厚みに応じて適宜選択され、例えば５ｍｍ以上３０ｍｍ以下程度である。軟質シール材の厚みを変えることで、基板間の距離を調整することができる。また、軟質シール材を押し潰すようにして２枚の基板を押圧することで、調製することもできる。
【００２４】
かかる重合セル内で組成物を重合させるには、通常のキャスト重合法と同様に、例えば組成物を重合セルの中に注入し、加熱すればよく、例えば第一有機過酸化物の１０時間半減温度（Ｔ_１）よりも５℃以上程度低い温度、通常は３０℃以上を１０時間以上維持した後、第三有機過酸化物の１０時間半減温度（Ｔ_３）よりも５℃以上程度高い温度、通常は１４０℃以下の温度まで昇温すればよい。昇温は段階的に行なってもよいし、連続的に行なってもよいが、段階的に行なうことが好ましい。段階的に昇温する場合、例えば第一有機過酸化物の１０時間半減温度（Ｔ_１）よりも５℃以上程度低い温度を１０時間以上維持した後、第一有機過酸化物の１０時間半減温度（Ｔ_１）よりも５℃程度未満低い温度〜１０℃程度以上高い温度の範囲を１時間以上維持し、次いで第二有機過酸化物の１０時間半減温度（Ｔ_２）よりも１０℃未満程度低い温度〜１０℃程度以上高い温度の範囲を１時間以上維持してから、第三有機過酸化物の１０時間半減温度（Ｔ_３）よりも５℃以上程度高い温度まで昇温する。昇温には、温水、温風、スチームなどを用いることができる。
【００２５】
かくして加熱することで、第一有機過酸化物、第二有機過酸化物および第三有機過酸化物が分解してラジカルが生成し、このラジカルによって組成物が重合して、目的の成形体が形成される。
【００２６】
重合させた後、通常のキャスト重合法と同様に、重合セルを解体して、目的の耐衝撃性メタクリル樹脂キャスト成形体を取出すことができる。かくして得られる耐衝撃性メタクリル樹脂キャスト成形体は、十分な耐衝撃性を有し、透明性に優れているので、例えば屋内の間仕切り、道路の遮音板、防弾板を構成する板材などとして有用である。
【００２７】
【発明の効果】
本発明の製造方法によれば、残存する単量体が少なく、十分な耐衝撃性を有していて、透明性がより高い耐衝撃性メタクリル樹脂キャスト成形体を製造することができる。
【００２８】
【実施例】
以下、実施例によって本発明をより詳細に説明するが、本発明は、かかる実施例によって限定されるものではない。
なお、各実施例において得られた成形体に含まれる残存単量体の含有量は、成形体から採取した０．１ｇの試料をジクロロメタン２０ｃｍ^３に溶解し、メチルイソブチルケトン（内部標準）１５ｍｍ^３を添加して試料溶液とし、この試料溶液に含まれる単量体成分をガスクロマトグラフィーにて定量して求めた。得られた成形体のヘーズは、ＪＩＳ　Ｋ７１３６に従って２３℃の恒温槽で１時間保持した後の成形体について測定した。得られた成形体のシャルピー衝撃強さは、ＪＩＳ　Ｋ７１１１に従って、試験片タイプ１で測定した。
【００２９】
実施例１
〔組成物の調製〕
メタクリル酸メチル７７．５質量部、メタクリル樹脂〔メタクリル酸メチル単位含有量が質量分率で９５％でありアクリル酸メチル単位含有量が質量分率で５％である共重合体、粘度平均分子量は約１１万〕１３．５質量部および３層構造弾性体粒子〔粒子径０．３μｍ〕９質量部を混合し、６０℃で２時間攪拌し、次いで冷却し、ｔ−ブチルパーオキシピバレート（Ｔ＝５５℃）を飽和脂肪族炭化水素溶媒に溶解させた溶液〔濃度は質量分率で７０％〕０．０２質量部（純分は０．０１４質量部）、ｔ−ブチルパーオキシ２−エチルヘキサノエート（Ｔ＝７２℃）〔純度は質量分率で９７％以上〕０．０２質量部（純分は約０．０２質量部）、ｔ−ブチルパーオキシイソプロピルカーボネート（Ｔ＝９９℃）を炭化水素溶媒に溶解させた溶液〔濃度は質量分率で７５％〕０．０４質量部（純分は０．０３質量部）、紫外線吸収剤〔「スミソーブ２００」、住友化学工業（株）より販売〕０．０１質量部および離型剤〔「サンセパラー１００」、三洋化成工業（株）より販売〕０．０５質量部を加え、更に１時間攪拌したのち、８７ｋＰａ（絶対圧力）で３０分間脱気して組成物を得た。
【００３０】
〔重合〕
軟質塩化ビニル製シール材を介して配置された２枚のガラス板〔３０ｃｍ×３０ｃｍ、厚み１０ｍｍ〕から構成される重合セルに、上記で得た組成物を注入し、加熱して、４６℃にて１６時間保温し、０．２５℃／分で５１℃に昇温して同温度で４時間保温し、０．４５℃／分で同温度から６０℃に昇温して同温度で３時間保温し、０．５℃／分で同温度から７０℃に昇温して同温度で次いで３時間保温し、０．５℃／分で同温度から８５℃に昇温して同温度で３時間保温し、０．５℃／分で同温度から１２０℃に昇温して同温度で２時間保温し、さらに１２０℃〜１２５℃の温度範囲で３時間保温した。加熱は、温風循環式加熱炉を用いた。
加熱したのち冷却し、重合セルを解体したところ、組成物が重合して、耐衝撃性メタクリル樹脂キャスト成形体（板状、３０ｃｍ×３０ｃｍ、厚みは１０ｍｍ）が形成されていた。
【００３１】
〔評価〕
この成形体から試験片を切り出し、残存単量体含有量、ヘーズおよびシャルピー衝撃強さを測定したところ、残存単量体含有量は０．９質量％、ヘーズは０．７％、シャルピー衝撃強さは３６ｋＪ／ｍ^２であった。評価結果を表１に示す。
【００３２】
実施例２
メタクリル酸メチル、メタクリル樹脂および３層構造弾性体粒子を混合したのち、６０℃で１３時間攪拌した以外は実施例１と同様に操作して、板状の耐衝撃性メタクリル樹脂キャスト成形体（板状）を得た。評価結果を表１に示す。
【００３３】
比較例１
ｔ−ブチルパーオキシピバレートの溶液、ｔ−ブチルパーオキシ２−エチルヘキサノエートの溶液およびｔ−ブチルパーオキシイソプロピルカーボネートの溶液に代えて、２，２−アゾビスイソブチロニトリル〔アゾ化合物、Ｔ＝６５℃〕０．０８質量部を単独で用いた以外は実施例１と同様に操作して、耐衝撃性メタクリル樹脂キャスト成形体（板状）を得た。評価結果を表１に示す。
【００３４】
比較例２
ｔ−ブチルパーオキシピバレートの溶液、ｔ−ブチルパーオキシ２−エチルヘキサノエートの溶液およびｔ−ブチルパーオキシイソプロピルカーボネートの溶液に代えて、ｔ−ブチルパーオキシ２−エチルヘキサノエート〔純度は質量分率で９７％以上〕０．０８質量部（純分は約０．０８質量部）を単独で用いた以外は実施例１と同様に操作して、耐衝撃性メタクリル樹脂キャスト成形体（板状）を得た。評価結果を表１に示す。
【００３５】
比較例３
ｔ−ブチルパーオキシピバレートの溶液に代えて、２，２’−アゾビス（２，４−ジメチルバレロニトリル）〔アゾ化合物、Ｔ＝５１℃〕０．０２質量部を用いた以外は実施例１と同様に操作して、耐衝撃性メタクリル樹脂キャスト成形体（板状）を得た。評価結果を表１に示す。
【００３６】
比較例４
ｔ−ブチルパーオキシピバレートの溶液、ｔ−ブチルパーオキシ２−エチルヘキサノエートの溶液およびｔ−ブチルパーオキシイソプロピルカーボネートの溶液に代えて、ジ−ｔ−ブチルパーオキシトリメチルアジペート（多官能有機過酸化物）をイソパラフィンに溶解させた溶液〔濃度は質量分率で５０％〕０．２３質量部（純分は０．１１５質量部）を単独で用いた以外は実施例１と同様に操作して、耐衝撃性メタクリル樹脂キャスト成形体（板状）を得た。評価結果を表１に示す。
【００３７】
【表１】

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for producing an impact-resistant methacrylic resin cast molded article.
[0002]
[Prior art]
The impact-resistant methacrylic resin cast molded article is a methacrylic resin molded article containing elastic particles and obtained by a cast polymerization method, and is useful as, for example, an indoor partition plate or a road sound insulation plate. Japanese Patent Application Laid-Open No. 8-151498 discloses a method for producing such an impact-resistant methacrylic resin cast molding, which includes a monomer having methyl methacrylate as a main component, a methacryl resin having a methyl methacrylate unit as a main component, and elastic particles. And a method of polymerizing a composition containing a polymerization initiator in a polymerization cell, and that an organic peroxide, an azo compound, or the like can be used as the polymerization initiator. It is required that such impact-resistant methacrylic resin casts have sufficient impact resistance, do not leave the used monomers, and are transparent.
[0003]
However, the impact-resistant methacrylic resin cast obtained by such a conventional production method has a relatively large amount of residual monomers and cannot be said to be sufficiently transparent.
[0004]
[Problems to be solved by the invention]
Accordingly, the present inventor has conducted intensive studies to develop a method capable of producing an impact-resistant methacrylic resin cast molded product having higher transparency, and as a result, as a polymerization initiator, a plurality of monofunctional organic polymers having different half-life temperatures for 10 hours. By using an oxide, the remaining monomer is small, has sufficient impact resistance, and found that a higher impact resistance methacrylic resin cast molded article having higher transparency can be produced. Reached.
[0005]
[Means for Solving the Problems]
That is, the present invention is a monomer having methyl methacrylate as a main component, a methacryl resin having a methyl methacrylate unit as a main component, elastic particles, the following first organic peroxide, the following second organic peroxide And a method for producing an impact-resistant methacrylic resin cast molded article, characterized in that a composition containing the following third organic peroxide is polymerized in a polymerization cell.
[0006]
First organic peroxide: monofunctional organic peroxide having a 10-hour half-life temperature of 60 ° C. or less Second organic peroxide: monofunctional organic peroxide having a 10-hour half-life temperature of more than 60 ° C. and 80 ° C. or less Third organic peroxide: a monofunctional organic peroxide having a half-life temperature of more than 80 ° C. for 10 hours.
BEST MODE FOR CARRYING OUT THE INVENTION
The monomers used in the production method of the present invention are those containing methyl methacrylate as a main component, and may contain methyl methacrylate alone or include a monomer copolymerizable with methyl methacrylate. It may be a mixture. Examples of monomers that can be copolymerized with methyl methacrylate include acrylates such as methyl acrylate, ethyl acrylate, and 2-ethylhexyl acrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, and methacrylic acid. Examples include methacrylic esters such as 2-ethylhexyl acid, methacrylic acid, maleic anhydride, styrene, cyclohexylmaleimide, and acrylonitrile. Here, the methacrylates do not include methyl methacrylate. Each of these copolymerizable monomers may be one type, or two or more types. In the case of a mixture containing a copolymerizable monomer, the content of methyl methacrylate in the mixture is 50% or more by mass fraction. Methyl methacrylate constituting a monomer containing methyl methacrylate as a main component or a monomer copolymerizable with methyl methacrylate may be an oligomer such as a dimer or a trimer.
[0008]
The methacrylic resin is a polymer having a methyl methacrylate unit as a main component. The methacrylic resin may be a homopolymer of methyl methacrylate composed of a single unit of methyl methacrylate, or a copolymer of methyl methacrylate and a monomer copolymerizable with methyl methacrylate. Examples of the monomer copolymerizable with methyl methacrylate include the same monomers as described above in the monomer containing methyl methacrylate as a main component. When the methacrylic resin is a copolymer, the content of methyl methacrylate units is 50% or more by mass fraction. The methacrylic resin usually has a viscosity average molecular weight of about 10,000 to 300,000.
[0009]
The elastic particles may be single-layer elastic particles composed of the elastic body alone. Further, a two-layered elastic particle composed of a core made of an elastic body and a methacrylic resin layer formed therearound, a core made of a methacrylic resin, and an intermediate layer made of an elastic body formed therearound, Multilayer elastic particles such as elastic particles having a three-layer structure including an outer layer made of methacrylic resin formed around the intermediate layer may be used. The particle size of such elastic particles is generally 0.1 μm or more and 1 μm or less, preferably about 0.2 μm or more and 0.8 μm or less. If the particle diameter is less than 0.1 μm, the impact resistance tends to be poor, and if it exceeds 1 μm, the transparency tends to decrease, which is not preferable. From the viewpoint that an impact-resistant methacrylic resin cast molded article having more excellent transparency can be obtained, multilayered elastic particles, particularly three-layered elastic particles are preferably used.
[0010]
The elastic particles are dispersed in a methacrylic resin and are resistant to, for example, “Sumipex HT01X” (sold by Sumitomo Chemical Co., Ltd.) and “Orograss DR” (sold by Sumika Haas Co.). It is commercially available as an impact methacrylic resin.
[0011]
The usage ratio of the methacrylic resin and the elastic particles is usually about 3: 7 to 7: 3 by mass. The total amount of the methacrylic resin and the elastic particles is usually about 10 to 40 parts by mass, where the total amount of the monomer, the methacrylic resin and the elastic particles is 100 parts by mass. If the amount is less than 10 parts by mass, the impact resistance becomes insufficient. If the amount exceeds 40 parts by mass, the viscosity of the composition tends to be high, and it tends to be difficult to fill the polymerization cell.
[0012]
In the production method of the present invention, the first organic peroxide, the second organic peroxide, and the third organic peroxide are used as the polymerization initiator. Organic peroxide has the formula (1)
Embedded image

Is an organic compound having a residue represented by In the organic peroxide, the residue (1) is decomposed to generate a radical. The 10-hour half-life temperature (T) is a temperature at which half of the organic peroxide is decomposed after 10 hours when the organic peroxide is heated alone, and specifically, dissolved in an inert solvent such as benzene. This is a temperature calculated based on the Arrhenius equation of the primary reaction, which is obtained by heating the solution obtained to a constant temperature and determining the amount of decomposition product produced over time.
[0013]
The organic peroxide used in the production method of the present invention is a monofunctional organic peroxide. Here, the monofunctional organic peroxide is an organic peroxide having one residue represented by the formula (1) in the molecule. For example, in the case of a polyfunctional organic peroxide having two or more residues (1) in a molecule such as di-t-butylperoxytrimethyl adipate, the amount of monomers remaining in the obtained molded article increases. There is a tendency.
[0014]
Examples of such a first organic peroxide include t-hexyl peroxy neodecanoate (T = 45 ° C.), dimethoxybutyl peroxy dicarbonate (T = 46 ° C.), t-butyl peroxy neodecanoate (T = 46 ° C), t-hexylperoxypivalate (T = 53 ° C), t-butylperoxypivalate (T = 55 ° C), 3,5,5-trimethylhexanoyl peroxide (T = 59 ° C) Organic peroxides having a 10-hour half-life temperature of 40 ° C. or higher, more preferably 50 ° C. or higher, are preferably used in terms of easy handling.
[0015]
Examples of the second organic peroxide include octanoyl peroxide (T = 62 ° C.), lauroyl peroxide (T = 62 ° C.), stearoyl peroxide (T = 62 ° C.), 1,1,3,3-tetra Methyl butyl peroxy 2-ethylhexanoate (66 ° C.), succinic peroxide (T = 66 ° C.), 1-cyclohexyl-1-methylethyl peroxy 2-ethylhexanoate (T = 68 ° C.), t -Hexylperoxy 2-ethylhexanoate (T = 70 ° C), t-butylperoxy-2-ethylhexanoate (T = 72 ° C), t-butylperoxyisobutyrate (T = 78 ° C), etc. Is mentioned.
[0016]
Examples of the third organic peroxide include t-hexylperoxyisopropyl monocarbonate (T = 95 ° C.), t-butylperoxymaleic acid (T = 96 ° C.), and t-butylperoxy-3,5,5. Trimethylhexanoate (T = 97 ° C.), t-butyl peroxy laurate (T = 98 ° C.), t-butyl peroxyisopropyl carbonate (T = 99 ° C.), t-butyl peroxy 2-ethylhexyl monocarbonate (T = 99 ° C), t-hexylperoxybenzoate (T = 99 ° C), t-butylperoxyacetate (T = 102 ° C), t-butylperoxybenzoate (t = 104 ° C), dicumyl peroxide (T = 119 ° C.) and t-butylcumyl peroxide (T = 120 ° C.). In that it can lower, 10 hours half-life temperature or less of the organic peroxide 110 ° C. are preferably used.
[0017]
The difference between the 10-hour half-life temperature of the first organic peroxide 10 hours half-life temperature of (T ₁₎ and a second organic peroxide (T _₂₎ (ΔT _₁₂₎ is impact-resistant methacrylic having more excellent transparency The temperature is preferably 10 ° C. or more, more preferably 13 ° C. or more, and usually 30 ° C. or less, from the viewpoint of obtaining a resin cast molded article. In addition, the difference (ΔT ₂₃ ) between the 10-hour half-life temperature (T ₂ ) of the second organic peroxide and the 10-hour half-life temperature (T ₃ ) of the third organic peroxide is more excellent in resistance to transparency. The temperature is preferably 10 ° C. or higher, more preferably 18 ° C. or higher, and usually 35 ° C. or lower, from the viewpoint of obtaining an impact-resistant methacrylic resin cast molded article.
[0018]
The ratio between the amount of the first organic peroxide used and the amount of the second organic peroxide used is about 3: 7 to 7: 3, preferably about 4: 6 to 6: 4 in terms of the amount of the substance, The ratio of the total used amount of the first organic peroxide and the second organic peroxide to the used amount of the third organic peroxide is about 3: 7 to 7: 3, preferably 4: 6 in terms of a substance amount ratio. About 6: 4, and the total amount of the first organic peroxide, the second organic peroxide and the third organic peroxide is 100 parts by mass of the monomer having methyl methacrylate as a main component. It is about 0.05 to 0.5 parts by weight per part.
[0019]
The first organic peroxide, the second organic peroxide and the third organic peroxide are usually used in a state diluted with an inert solvent. Here, the inert solvent is appropriately selected according to the type of these organic peroxides, for example, naphtha, a saturated aliphatic hydrocarbon solvent such as polymerized gasoline, benzene, a hydrocarbon solvent such as toluene, acetone, cumene, Examples include diphenylethane and ethyl acetate.
[0020]
Such a monomer, methacrylic resin, elastic particles, the first organic peroxide, the composition containing the second organic peroxide and the third organic peroxide, the intended impact-resistant methacrylic resin cast moldings Depending on the use, additives such as an antioxidant, an ultraviolet absorber, a release agent, and a dye may be contained.
[0021]
In the production method of the present invention, such a composition is polymerized in a polymerization cell. In the production method of the present invention, such a composition is polymerized in a polymerization cell, so that it has sufficient impact resistance, has a low monomer content, and has excellent transparency and is an impact-resistant methacrylic resin cast molded article. Can be obtained.
[0022]
As the polymerization cell, a polymerization cell used in a normal cast polymerization method can be used. For example, when the target impact-resistant methacrylic resin cast molded body is a plate, two substrates arranged in parallel with each other are used. And a continuous cell composed of two continuous belts arranged in parallel with each other.
[0023]
When a batch-type cell is used, for example, a glass substrate or a metal substrate can be used as the substrate. These two substrates are arranged via a soft sealing material, and the composition is polymerized in a region surrounded by the two substrates and the soft sealing material. The distance between the substrates is appropriately selected according to the thickness of the target plate-like molded body, and is, for example, about 5 mm or more and 30 mm or less. By changing the thickness of the soft sealing material, the distance between the substrates can be adjusted. Alternatively, it can be prepared by pressing two substrates so as to crush the soft sealing material.
[0024]
In order to polymerize the composition in such a polymerization cell, for example, the composition may be injected into the polymerization cell and heated in the same manner as in a normal cast polymerization method, for example, the first organic peroxide may be reduced by half for 10 hours. After maintaining the temperature about 5 ° C. or more lower than the temperature (T ₁ ), usually 30 ° C. or more for 10 hours or more, a temperature about 5 ° C. or more higher than the 10-hour half-life temperature (T ₃ ) of the third organic peroxide. Usually, the temperature may be raised to a temperature of 140 ° C. or lower. The temperature may be raised stepwise or continuously, but preferably stepwise. When the temperature is increased stepwise, for example, after maintaining a temperature that is about 5 ° C. or more lower than the 10-hour half-life temperature (T ₁ ) of the first organic peroxide for 10 hours or more, the first organic peroxide is reduced by 10-hour half-life. Maintain a temperature range lower than about 5 ° C. lower than the temperature (T ₁ ) by about 10 ° C. or higher for 1 hour or more, and then lower than 10 ° C. lower than the 10-hour half-life temperature (T ₂ ) of the second organic peroxide by 10 hours. After maintaining the temperature range of about a low temperature to about 10 ° C. or higher, for 1 hour or more, the temperature is raised to a temperature about 5 ° C. or more higher than the 10 hour half-life temperature (T ₃ ) of the third organic peroxide. For raising the temperature, hot water, hot air, steam, or the like can be used.
[0025]
By heating in this manner, the first organic peroxide, the second organic peroxide, and the third organic peroxide are decomposed to generate radicals, and the radicals cause the composition to polymerize, thereby forming a target molded body. It is formed.
[0026]
After the polymerization, the polymerization cell can be disassembled in the same manner as in a usual cast polymerization method to take out a target impact-resistant methacrylic resin cast molded article. The impact-resistant methacrylic resin cast molded product thus obtained has sufficient impact resistance and excellent transparency, so that it is useful as, for example, an indoor partition, a sound insulation plate for roads, and a plate material constituting a bulletproof plate. is there.
[0027]
【The invention's effect】
According to the production method of the present invention, an impact-resistant methacrylic resin cast molded article having a small amount of residual monomer, sufficient impact resistance, and higher transparency can be produced.
[0028]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.
In addition, the content of the residual monomer contained in the molded article obtained in each of the examples was determined by dissolving 0.1 g of a sample collected from the molded article in 20 cm ³ of dichloromethane and 15 mm ^{3 of} methyl isobutyl ketone (internal standard). Was added to obtain a sample solution, and the monomer components contained in the sample solution were quantified and determined by gas chromatography. The haze of the obtained molded body was measured in accordance with JIS K7136, after maintaining the molded body in a thermostat at 23 ° C. for 1 hour. The Charpy impact strength of the obtained molded body was measured with a test piece type 1 according to JIS K7111.
[0029]
Example 1
(Preparation of composition)
77.5 parts by mass of methyl methacrylate, a methacrylic resin [a copolymer having a methyl methacrylate unit content of 95% by mass fraction and a methyl acrylate unit content of 5% by mass fraction, a viscosity average molecular weight of About 110,000] 13.5 parts by mass and 9 parts by mass of the three-layer structured elastic particles [particle size 0.3 μm] were stirred at 60 ° C for 2 hours, then cooled, and t-butyl peroxypivalate ( T = 55 ° C.) in a saturated aliphatic hydrocarbon solvent [concentration is 70% by mass fraction] 0.02 parts by mass (the pure portion is 0.014 parts by mass), t-butylperoxy 2- Ethyl hexanoate (T = 72 ° C.) [Purity is 97% or more by mass fraction] 0.02 parts by mass (pure matter is about 0.02 parts by mass), t-butyl peroxyisopropyl carbonate (T = 99 ° C.) ) In a hydrocarbon solvent [Concentration: 75% by mass fraction] 0.04 parts by mass (pure content: 0.03 parts by mass), ultraviolet absorber ["Sumisorb 200", sold by Sumitomo Chemical Co., Ltd.] 0.01 parts by mass and 0.05 parts by mass of a release agent [“Sanseparar 100”, sold by Sanyo Chemical Industry Co., Ltd.] was added, and the mixture was further stirred for 1 hour and then degassed at 87 kPa (absolute pressure) for 30 minutes to obtain a composition. .
[0030]
〔polymerization〕
The composition obtained above was poured into a polymerization cell composed of two glass plates (30 cm × 30 cm, thickness 10 mm) arranged via a soft vinyl chloride sealing material, and heated to 46 ° C. For 16 hours, raise the temperature to 51 ° C at a rate of 0.25 ° C / min, keep it for 4 hours at the same temperature, and raise the temperature from the same temperature to 60 ° C at a rate of 0.45 ° C / min for 3 hours at the same temperature Incubate at 0.5 ° C / min from the same temperature to 70 ° C, then at the same temperature for 3 hours, and then at 0.5 ° C / min from the same temperature to 85 ° C and The temperature was maintained at 0.5 ° C./min from the same temperature to 120 ° C., kept at the same temperature for 2 hours, and further kept at a temperature range of 120 ° C. to 125 ° C. for 3 hours. For heating, a hot air circulation type heating furnace was used.
When heated and cooled and the polymerization cell was disassembled, the composition was polymerized to form an impact-resistant methacrylic resin cast molded product (plate-like, 30 cm × 30 cm, thickness 10 mm).
[0031]
[Evaluation]
A test piece was cut out from the molded body, and the residual monomer content, haze and Charpy impact strength were measured. The residual monomer content was 0.9% by mass, haze was 0.7%, and Charpy impact strength was measured. The height was 36 kJ / m ² . Table 1 shows the evaluation results.
[0032]
Example 2
After mixing methyl methacrylate, methacrylic resin, and three-layer structured elastic particles, the same operation as in Example 1 was carried out except that the mixture was stirred at 60 ° C. for 13 hours to obtain a plate-like impact-resistant methacrylic resin cast (plate). ) Was obtained. Table 1 shows the evaluation results.
[0033]
Comparative Example 1
Instead of a solution of t-butyl peroxypivalate, a solution of t-butyl peroxy 2-ethylhexanoate and a solution of t-butyl peroxyisopropyl carbonate, 2,2-azobisisobutyronitrile [azo compound , T = 65 ° C.] An impact-resistant methacrylic resin cast (plate) was obtained in the same manner as in Example 1 except that 0.08 parts by mass was used alone. Table 1 shows the evaluation results.
[0034]
Comparative Example 2
Instead of a solution of t-butyl peroxypivalate, a solution of t-butyl peroxy 2-ethylhexanoate and a solution of t-butyl peroxyisopropyl carbonate, t-butyl peroxy 2-ethylhexanoate [purity Is 97% or more by mass fraction] The same procedure as in Example 1 was carried out, except that 0.08 parts by mass (the pure component was about 0.08 parts by mass) was used alone, to thereby produce a cast article of an impact-resistant methacrylic resin. (Plate shape) was obtained. Table 1 shows the evaluation results.
[0035]
Comparative Example 3
Example 1 Example 2 was repeated except that 0.02 parts by mass of 2,2′-azobis (2,4-dimethylvaleronitrile) [azo compound, T = 51 ° C.] was used instead of the solution of t-butyl peroxypivalate. In the same manner as in the above, an impact-resistant methacrylic resin cast molding (plate-like) was obtained. Table 1 shows the evaluation results.
[0036]
Comparative Example 4
Instead of a solution of t-butyl peroxypivalate, a solution of t-butyl peroxy 2-ethylhexanoate and a solution of t-butyl peroxyisopropyl carbonate, di-t-butyl peroxytrimethyl adipate (polyfunctional organic Peroxide) dissolved in isoparaffin [concentration is 50% by mass fraction] The same operation as in Example 1 was performed except that 0.23 parts by mass (0.115 parts by mass of pure portion) was used alone. Thus, an impact-resistant methacrylic resin cast molding (plate shape) was obtained. Table 1 shows the evaluation results.
[0037]
[Table 1]

Claims

Monomer containing methyl methacrylate as a main component, methacryl resin containing methyl methacrylate unit as a main component, elastic particles, the following first organic peroxide, the following second organic peroxide and the following third A method for producing an impact-resistant methacrylic resin cast molded article, comprising polymerizing a composition containing an organic peroxide in a polymerization cell.
First organic peroxide: monofunctional organic peroxide having a 10-hour half-life temperature of 60 ° C. or less Second organic peroxide: monofunctional organic peroxide having a 10-hour half-life temperature of more than 60 ° C. and 80 ° C. or less Tertiary organic peroxide: monofunctional organic peroxide with a 10-hour half-life temperature exceeding 80 ° C.

2. The method according to claim 1, wherein the elastic particles are multilayer elastic particles.

The difference between the 10-hour half-life temperature of the first organic peroxide and the 10-hour half-life temperature of the second organic peroxide is 10 ° C. or more, and the 10-hour half-life temperature of the second organic peroxide and the third organic peroxide 2. The method according to claim 1, wherein the difference from the 10-hour half-life temperature of the product is 10 ° C. or more.

The usage ratio of methacrylic resin and elastic particles is 3: 7 to 7: 3 by mass ratio, and the total usage of methacrylic resin and elastic particles is the total usage of monomer, methacrylic resin and elastic particles. The production method according to claim 1, wherein the amount is 10 parts by mass or more and 40 parts by mass or less based on 100 parts by mass.

The ratio of the usage amount of the first organic peroxide to the usage amount of the second organic peroxide is 3: 7 to 7: 3 in terms of the mass ratio, and the first organic peroxide and the second organic peroxide are used. And the ratio of the amount of the third organic peroxide to the amount of the third organic peroxide is 3: 7 to 7: 3 in terms of the amount of the substance, and the first organic peroxide, the second organic peroxide and the third organic peroxide are used. The production method according to claim 4, wherein the total amount of the oxide is 0.05 to 0.5 part by mass per 100 parts by mass of the monomer containing methyl methacrylate as a main component.

After maintaining the temperature at least 5 ° C. lower than the 10-hour half-life temperature of the first organic peroxide for 10 hours or more, the temperature is raised to a temperature at least 5 ° C. higher than the 10-hour half-life temperature of the third organic peroxide to perform polymerization. The method according to claim 1, wherein:

After maintaining a temperature of at least 5 ° C. lower than the 10-hour half-life temperature of the first organic peroxide for 10 hours or more, a temperature lower than 5 ° C. lower than the 10-hour half-life temperature of the first organic peroxide and higher than 10 ° C. or more Is maintained for 1 hour or more, and then a temperature that is lower than 10 ° C. and lower than 10 ° C. than the 10-hour half-life temperature of the second organic peroxide is maintained for 1 hour or more, and then the third organic peroxide is maintained for 10 hours. The production method according to claim 6, wherein the temperature is raised to a temperature higher by at least 5 ° C than the half-life temperature.

Monomer containing methyl methacrylate as a main component, methacryl resin containing methyl methacrylate unit as a main component, elastic particles, the following first organic peroxide, the following second organic peroxide and the following third A composition comprising an organic peroxide.
First organic peroxide: monofunctional organic peroxide having a 10-hour half-life temperature of 60 ° C. or less Second organic peroxide: monofunctional organic peroxide having a 10-hour half-life temperature of more than 60 ° C. and 80 ° C. or less Tertiary organic peroxide: monofunctional organic peroxide with a 10-hour half-life temperature exceeding 80 ° C.

An impact-resistant methacrylic resin cast molded article obtained by polymerizing the composition according to claim 8 in a polymerization cell.