JP4558123B2 - Rubber-modified styrenic resin composition and injection-molded product thereof - Google Patents

Description

【数４】

【０００８】
好ましくは、上記ゴム変性スチレン系樹脂組成物において、スチレン−（メタ）アクリル酸エステル系共重合体の連続相とグラフト共重合体の分散相との屈折率の差が０．００５以下であるゴム変性スチレン系樹脂組成物およびその射出成形品である。
【０００９】
さらに好ましくは、上記ゴム変性スチレン系樹脂組成物において、グラフト共重合体の分散相が、体積平均粒子径０．３〜０．６μｍで、その標準偏差０．０８〜０．２μｍであるゴム変性スチレン系樹脂組成物およびその射出成形品である。
【００１０】
以下、本発明を詳細に説明する。本発明のゴム変性スチレン系樹脂組成物の連続相を構成するスチレン−（メタ）アクリル酸エステル系共重合体とは、スチレン系単量体、（メタ）アクリル酸エステル系単量体、および必要に応じて用いられるこれらの単量体と共重合可能なビニル系単量体からなる共重合体である。
【００１１】
また、本発明のゴム変性スチレン系樹脂組成物の分散相を構成するグラフト共重合体とは、ゴム状弾性体に、スチレン系単量体、（メタ）アクリル酸エステル系単量体、および必要に応じて用いられるこれらの単量体と共重合可能なビニル系単量体からなるスチレン−（メタ）アクリル酸エステル系共重合体がグラフトしてなる共重合体である。
【００１２】
本発明の連続相および分散相において使用されるスチレン系単量体は、スチレン、α−メチルスチレン、ｐ−メチルスチレン、ｏ−メチルスチレン、ｍ−メチルスチレン、エチルスチレン、ｐ−ｔ−ブチルスチレン等を挙げることができるが、好ましくはスチレンである。これらのスチレン系単量体は、単独でもよいが二種以上を併用してもよい。
【００１３】
本発明で使用される（メタ）アクリル酸エステル系単量体としては、メチルメタクリレート、エチルメタクリレート、ブチルメタクリレート、２−エチルヘキシルメタクリレート等のメタクリル酸エステル、メチルアクリレート、エチルアクリレート、ｎ−ブチルアクリレート、２−メチルヘキシルアクリレート、２−エチルヘキシルアクリレート、デシルアクリレート等のアクリル酸エステルが挙げられるが、好ましくはメチルメタクリレート、またはｎ−ブチルアクリレートであり、特に好ましくはメチルメタクリレートである。これらの（メタ）アクリル酸エステル系単量体は単独で用いてもよいが二種以上を併用してもよい。
【００１４】
さらに、必要に応じて用いられるこれらの単量体と共重合可能なビニル系単量体としては、アクリル酸、メタクリル酸、アクリロニトリル、メタアクリロニトリル、Ｎ−フェニルマレイミド、Ｎ−シクロヘキシルマレイミド等が挙げられる。
【００１５】
本発明で使用されるゴム状弾性体としては、ポリブタジエン、スチレン−ブタジエンブロック共重合体、およびスチレン−ブタジエンランダム共重合体等が挙げられる。
スチレン−ブタジエンブロック共重合体、あるいはスチレン−ブタジエンランダム共重合体中におけるスチレン量は、６０質量％以下であることがゴム変性スチレン系樹脂組成物の良好な耐衝撃性と透明性を得るために好ましい。
【００１６】
本発明のゴム変性スチレン系樹脂組成物は、スチレン−（メタ）アクリル酸エステル系共重合体の連続相６０〜９０質量％とグラフト共重合体の分散相４０〜１０質量％からなる。グラフト共重合体１０質量％未満では耐衝撃性が不十分であり、４０質量％を超えると剛性および表面硬度が劣るために好ましくない。
【００１７】
なお、連続相と分散相の質量比測定は、ゴム変性スチレン系樹脂組成物（質量をＡとする）をメチルエチルケトン（ＭＥＫ）中で温度２３℃で２４時間攪拌し、その後遠心分離機でＭＥＫに対する不溶分を分離、真空乾燥したものを質量測定して（質量をＢとする）、次の数５式、数６式により求めるものである。
【数５】

【数６】

【００１８】
さらに、前記グラフト共重合体の分散相は、体積平均粒子径が０．３〜０．６μｍおよびトルエン膨潤倍率が３〜８倍である。体積平均粒子径が０．３μｍ未満では耐衝撃性が不十分であり、０．６μｍを越えると透明性が劣るために好ましくない。また、トルエン膨潤倍率が３倍未満では耐衝撃性が不十分であり、８倍を越えると透明性および表面硬度が劣るために好ましくない。
【００１９】
なお、分散相のトルエン膨潤倍率は、ゴム変性スチレン系樹脂組成物から分離した分散相（質量をＣとする）をトルエンに温度２３℃で２４時間膨潤させた後、１５０メッシュ金網で濾別し、直ちに質量測定して（質量をＤとする）、次の数７式により求めるものである。
【数７】

【００２０】
さらに、特に透明性が要求される場合および／または特に面衝撃に代表される実用強度が要求される場合には、体積平均粒子径が０．３〜０．６μｍで、その標準偏差が０．０８〜０．２μｍであることが好ましい。
【００２１】
また、前記スチレン−（メタ）アクリル酸エステル系共重合体の連続相は、重量平均分子量（Ｍｗ）とその構成単量体単位から求められる数８式のＸが数９式の範囲にあることが必要である。ただし、ここで述べる連続相の重量平均分子量とは、前記したゴム変性スチレン系樹脂組成物のＭＥＫ可溶分をゲルパーミエーションクロマトグラフィー（ＧＰＣ）法で測定したポリスチレン換算の重量平均分子量である。
【００２２】
【数８】

【数９】

Ｘが１０００００未満では耐衝撃性が不十分であり、１８００００を越えると成形加工性が劣るため好ましくない。
【００２３】
また、本発明のゴム変性スチレン系樹脂組成物は、スチレン−（メタ）アクリル酸エステル系共重合体からなる連続相とグラフト共重合体の分散相との屈折率の差が０．００５以下であることが良好な透明性を得るために好ましい。
【００２４】
但し、グラフト共重合体の屈折率を実測することは難しいため、一般的には組成分析によりポリマーを構成する単量体の組成比を算出することで、グラフト共重合体の屈折率ｎは次の数１０式を用いて計算により屈折率を求めることが出来る。
【数１０】

すなわち、グラフト共重合体の組成が、Ａｍ単量体、Ｂｍ単量体およびＣｍ単量体からなり、かつそれぞれの質量比がＸ_A、Ｘ_BおよびＸ_Cからなる場合（但し、質量比でＸ_A＋Ｘ_B＋Ｘ_C＝１）、ｎ_AはＡｍ単量体からなるポリマーの屈折率、ｎ_BはＢｍ単量体からなるポリマーの屈折率、ｎ_CはＣｍ単量体からなるポリマーの屈折率を示すものとし、上式数１０に代入して計算より求めるものである。
【００２５】
なお、連続相のスチレン−（メタ）アクリル酸エステル系共重合体を構成する各単量体の量は、前記した条件を満たせば特に限定されるものではないが、好ましくはスチレン系単量体単位２０〜７０質量％、（メタ）アクリル酸エステル系単量体単位３０〜８０質量％、および必要に応じて用いられるこれらの単量体と共重合可能なビニル系単量体単位０〜１０質量％である。
【００２６】
また、分散相のグラフト共重合体を構成するゴム状弾性体及び各単量体の量は、前記した条件を満たせば特に限定されるものではないが、ゴム状弾性体３０〜８０質量部に、スチレン系単量体単位２０〜７０質量％、（メタ）アクリル酸エステル系単量体単位３０〜８０質量％、および必要に応じて用いられるこれらの単量体と共重合可能なビニル系単量体単位０〜１０質量％からなるスチレン−（メタ）アクリル酸エステル系共重合体２０〜７０質量部がグラフトしたグラフト共重合体が好ましく用いられる。
【００２７】
本発明のゴム変性スチレン系樹脂組成物は、塊状重合法、溶液重合法、懸濁重合法、塊状−懸濁重合法、乳化重合法等の公知技術により製造することができる。また、回分式重合法、連続式重合法のいずれの方法も用いることができる。
【００２８】
本発明のゴム変性スチレン系樹脂組成物には、公知の酸化防止剤、耐候剤、滑剤、可塑剤、着色剤、帯電防止剤、鉱油等の添加剤を、本発明のゴム変性スチレン系樹脂組成物の性能を損なわない範囲で配合してもよい。
【００２９】
本発明のゴム変性スチレン系樹脂組成物は、配合・溶融押出しについて特に制限はなく、公知の方法を採用することができる。例えば、各原料をあらかじめタンブラーやヘンシェルミキサー等で均一に混合して、単軸押出機または二軸押出機等に供給して溶融混練した後、ペレットとして調整する方法がある。
このようにして得られた本発明のゴム変性スチレン系樹脂組成物は、例えば、射出成形、圧縮成形および押出成形等の方法により各種成形体に加工され実用に供することができるが、本発明のゴム変性スチレン系樹脂組成物は、優れた透明性、耐衝撃性、剛性、表面硬度、および成形加工性を有しているため、このゴム変性スチレン系樹脂組成物を射出成形してなる射出成形品は、実用的に極めて優れたものである。
【００３０】
【実施例】
次に実施例をもって本発明をさらに説明するが、本発明はこれらの例に限定されるものではない。
【００３１】
まず、原料樹脂の製造から示す。
（イ）スチレン−（メタ）アクリル酸エステル系共重合体の製造
参考例１：スチレン−（メタ）アクリル酸エステル系共重合体Ａ−１
容量２５０リットルのオートクレーブに、純水１００ｋｇにドデシルベンゼンスルホン酸ナトリウムを０．５ｇ、第三リン酸カルシウム２５０ｇ、スチレン４１ｋｇ、メチルメタクリレート５６ｋｇ、アクリロニトリル３ｋｇを入れ、重合開始剤としてｔ−ブチルパーオキシイソブチレートを１００ｇ、ｔ−ドデシルメルカプタン３００ｇを添加し、回転数１５０ｒｐｍの撹拌下に混合液を分散させた。そしてこの混合液を温度９０℃で８時間、１３０℃で２．５時間加熱重合させた。反応終了後、洗浄、脱水後乾燥し、ビーズ状のスチレン−（メタ）アクリル酸エステル系共重合体Ａ−１を得た。
【００３２】
参考例２：スチレン−（メタ）アクリル酸エステル系共重合体Ａ−２
参考例１において、ｔ−ドデシルメルカプタンを７００ｇに変更した以外はスチレン−（メタ）アクリル酸エステル系共重合体Ａ−１と同様に製造し、ビーズ状のスチレン−（メタ）アクリル酸エステル系共重合体Ａ−２を得た。
【００３３】
参考例３：スチレン−（メタ）アクリル酸エステル系共重合体Ａ−３
容量２５０リットルのオートクレーブに、純水１００ｋｇにドデシルベンゼンスルホン酸ナトリウムを０．５ｇ、第三リン酸カルシウム２５０ｇ、スチレン２３ｋｇ、メチルメタクリレート７３ｋｇ、アクリロニトリル４ｋｇを入れ、重合開始剤としてｔ−ブチルパーオキシイソブチレートを１００ｇ、ｔ−ドデシルメルカプタン７００ｇを添加し、回転数１５０ｒｐｍの撹拌下に混合液を分散させた。そしてこの混合液を温度９０℃で８時間、１３０℃で２．５時間加熱重合させた。反応終了後、洗浄、脱水後乾燥し、ビーズ状のスチレン−（メタ）アクリル酸エステル系共重合体Ａ−３を得た。
【００３４】
参考例４：スチレン−（メタ）アクリル酸エステル系共重合体Ａ−４
参考例３において、ｔ−ドデシルメルカプタンを３００ｇに変更した以外はスチレン−（メタ）アクリル酸エステル系共重合体Ａ−３と同様に製造し、ビーズ状のスチレン−（メタ）アクリル酸エステル系共重合体Ａ−４を得た。
【００３５】
（ロ）ゴム状弾性体ラテックスの製造
参考例５：ゴム状弾性体ラテックスＧ−１
容積２００リットルのオートクレーブに純水１１５ｋｇ、オレイン酸カリウム５００ｇ、ピロリン酸ナトリウム７５ｇ、硫酸第一鉄１．５ｇ、エチレンジアミンテトラ酢酸ナトリウム２．２ｇ、ロンガリット２２ｇを加えて撹拌下で均一に溶解した。次いでスチレン１２．５ｋｇ、ブタジエン３７．５ｋｇ、ｔ−ドデシルメルカプタン１４８ｇ、ジビニルベンゼン３０ｇ、ジイソプロピルベンゼンハイドロパーオキサイド９６ｇを加え、撹拌しながら温度５０℃で１６時間反応を行って重合を完結し、ゴム状弾性体ラテックスを得た。得られたゴム状弾性体ラテックスにナトリウムスルホサクシネート４５ｇを添加して充分安定化した後、０．２質量％塩酸水溶液と２質量％苛性ソーダ水溶液を別々のノズルから、ラテックスのＰＨが８〜９を保つように添加し、ラテックスを凝集肥大化させ、体積平均粒子径０．４２μｍのゴム状弾性体ラテックスＧ−１を得た。
【００３６】
参考例６：ゴム状弾性体ラテックスＧ−２
参考例５において、凝集肥大化の条件を変えて体積平均粒子径を０．６３μｍにした以外はゴム状弾性体ラテックスＧ−１と同様に製造し、ゴム状弾性体ラテックスＧ−２を得た。
【００３７】
参考例７：ゴム状弾性体ラテックスＧ−３
容積２００リットルのオートクレーブに純水８５ｋｇ、オレイン酸カリウム１２００ｇ、水酸化カリウム２００ｇ、過硫酸カリウム５０ｇを加えて撹拌下で均一に溶解した。次いでブタジエン５０ｋｇ、ｔ−ドデシルメルカプタン１００ｇ、ジビニルベンゼン５０ｇを加え、撹拌しながら温度５０℃で１６時間反応を行って重合を完結し、ゴム状弾性体ラテックスを得た。得られたゴム状弾性体ラテックスをマントンゴーリン式加圧凝集肥大機を利用して、ラテックスを凝集肥大化させ、体積平均粒子径０．３５μｍのゴム状弾性体ラテックスＧ−３を得た。
【００３８】
参考例８：ゴム状弾性体ラテックスＧ−４
容積２００リットルのオートクレーブに純水５６ｋｇ、オレイン酸カリウム４００ｇ、ロジン酸カリウム１２００ｇ、炭酸ナトリウム１．２ｋｇ、過硫酸カリウム４００ｇを加えて撹拌下で均一に溶解した。次いでブタジエン８０ｋｇ、ｔ−ドデシルメルカプタン４００ｇを加え、撹拌しながら温度６０℃で３０時間重合し、さらに７０℃に昇温して３０時間放置して重合を完結し、体積平均粒子径０．３４μｍのゴム状弾性体ラテックスＧ−４を得た。
【００３９】
参考例９：ゴム状弾性体ラテックスＧ−５
容積２００リットルのオートクレーブに純水６４ｋｇ、オレイン酸カリウム１６８０ｇ、ロジン酸カリウム１６０ｇ、炭酸ナトリウム１．２ｋｇ、炭酸水素ナトリウム２０ｇ、過硫酸カリウム４００ｇを加えて撹拌下で均一に溶解した。次いでスチレン２０ｋｇ、ブタジエン６０ｋｇ、ｔ−ドデシルメルカプタン３２０ｇを加え、撹拌しながら５５℃で１６時間重合し、さらに温度７０℃に昇温して８時間放置して重合を完結し、体積平均粒子径０．１９μｍのゴム状弾性体ラテックスＧ−５を得た。
【００４０】
（ハ）グラフト共重合体含有重合体の製造
参考例１０：グラフト共重合体含有重合体Ｂ−１
参考例５のゴム状弾性体ラテックスＧ−１を固形分換算で３０ｋｇ計量して容積２００Ｌのオートクレーブに移し、純水８０ｋｇを加え、攪拌しながら窒素気流下で温度５０℃に昇温した。ここに硫酸第一鉄１．２５ｇ、エチレンジアミンテトラ酢酸ナトリウム２．５ｇ、ロンガリット１００ｇを溶解した純水２ｋｇを加え、スチレン１２．９ｋｇ、メチルメタクリレート１７．１ｋｇ、ｔ−ドデシルメルカプタン６０ｇからなる混合物と、ジイソプロピルベンゼンハイドロパーオキサイド１２０ｇをオレイン酸カリウム４５０ｇを含む純水８ｋｇに分散した溶液とを、別々に６時間かけて連続添加した。添加終了後、温度を７０℃に昇温して、さらにジイソプロピルベンゼンハイドロパーオキサイド３０ｇ添加した後２時間放置して重合を終了した。
得られた乳化液に酸化防止剤を加え、純水で固形分を１５質量％に希釈した後に温度６０℃に昇温し、激しく撹拌しながら希硫酸を加えて塩析を行い、その後温度を９０℃に昇温して凝固させ、次に脱水、水洗、乾燥して粉末状のグラフト共重合体含有重合体Ｂ−１を得た。
【００４１】
参考例１１：グラフト共重合体含有重合体Ｂ−２
参考例１０において、ゴム状弾性体ラテックスがゴム状弾性体ラテックスＧ−２に変更された以外は、グラフト共重合体含有重合体Ｂ−１と同様に製造し、粉末状のグラフト共重合体含有重合体Ｂ−２を得た。
【００４２】
参考例１２：グラフト共重合体含有重合体Ｂ−３
参考例１０において、ゴム状弾性体ラテックスとしてゴム状弾性体ラテックスＧ−２が固形換算で１５ｋｇとゴム状弾性体ラテックスＧ−５が固形分換算で１５ｋｇとの併用に変更された以外は、グラフト共重合体含有重合体Ｂ−１と同様に製造し、粉末状のグラフト共重合体含有重合体Ｂ−３を得た。
【００４３】
参考例１３：グラフト共重合体含有重合体Ｂ−４
参考例１０において、ゴム状弾性体ラテックスがゴム状弾性体ラテックスＧ−５に変更された以外は、グラフト共重合体含有重合体Ｂ−１と同様に製造し、粉末状のグラフト共重合体含有重合体Ｂ−４を得た。
【００４４】
参考例１４：グラフト共重合体含有重合体Ｂ−５
参考例７のゴム状弾性体ラテックスＧ−３を固形分換算で３０ｋｇ計量して容積２００Ｌのオートクレーブに移し、純水８０ｋｇを加え、攪拌しながら窒素気流下で温度５０℃に昇温した。ここに硫酸第一鉄１．２５ｇ、エチレンジアミンテトラ酢酸ナトリウム２．５ｇ、ロンガリット１００ｇを溶解した純水２ｋｇを加え、スチレン６．９ｋｇ、メチルメタクリレート２３．１ｋｇ、ｔ−ドデシルメルカプタン６０ｇからなる混合物と、ジイソプロピルベンゼンハイドロパーオキサイド１２０ｇをオレイン酸カリウム４５０ｇを含む純水８ｋｇに分散した溶液とを、別々に６時間かけて連続添加した。添加終了後、温度を７０℃に昇温して、さらにジイソプロピルベンゼンハイドロパーオキサイド３０ｇ添加した後２時間放置して重合を終了した。
得られた乳化液に酸化防止剤を加え、純水で固形分を１５質量％に希釈した後に温度６０℃に昇温し、激しく撹拌しながら希硫酸を加えて塩析を行い、その後温度を９０℃に昇温して凝固させ、次に脱水、水洗、乾燥して粉末状のグラフト共重合体含有重合体Ｂ−５を得た。
【００４５】
参考例１５：グラフト共重合体含有重合体Ｂ−６
参考例１４において、ゴム状弾性体ラテックスがゴム状弾性体ラテックスＧ−４に変更された以外は、グラフト共重合体含有重合体Ｂ−５と同様に製造し、粉末状のグラフト共重合体含有重合体Ｂ−６を得た。
【００４６】
参考例１６：グラフト共重合体含有重合体Ｂ−７
参考例１４において、ゴム状弾性体ラテックスとしてゴム状弾性体ラテックスＧ−３が固形換算で１５ｋｇとゴム状弾性体ラテックスＧ−４が固形分換算で１５ｋｇとの併用に変更された以外は、グラフト共重合体含有重合体Ｂ−５と同様に製造し、粉末状のグラフト共重合体含有重合体Ｂ−７を得た。
【００４７】
参考例１７：グラフト共重合体含有重合体Ｂ−８
容積１００リットルのオートクレーブ中でスチレン３２．３ｋｇ、メチルメタクリレート４３．７ｋｇの単量体混合物にスチレン−ブタジエン共重合体（スチレン含量２５％、旭化成社製タフデン２０００（商品名））４ｋｇを溶解し、重合開始剤としてベンゾイルパーオキサイド３２ｇ、連鎖移動剤としてｔ−ドデシルメルカプタン１６０ｇを添加し、撹拌翼の回転数を２６０ｒｐｍに設定し、温度９０℃に加熱した。重合転化率が３０質量％に達した時に冷却して塊状重合を停止した。
次いで該反応混合液７０ｋｇを容積２００リットルのオートクレーブに移し、これに新たに重合開始剤としてジクミルパーオキサイドを１４０ｇ添加した。純水１００ｋｇにドデシルベンゼンスルホン酸ナトリウムを０．５ｇ、第三リン酸カルシウム３５０ｇを懸濁安定剤として添加し、撹拌下に混合液を分散させた。
反応系を温度１００℃で２時間、１１５℃で３．５時間、１３０℃で２．５時間加熱重合させた。反応終了後、洗浄、脱水後乾燥し、ビーズ状のグラフト共重合体含有重合体Ｂ−８を得た。
【００４８】
実施例および比較例
参考例１〜４で製造したスチレン−（メタ）アクリル酸エステル系共重合体および参考例１０〜１７で製造したグラフト共重合体含有重合体を表１、２で示した割合（質量％）で配合してヘンシェルミキサーで混合した後、二軸押出機（東芝機械（株）社製 ＴＥＭ−３５Ｂ）でシリンダー温度２２０℃で溶融混練してペレット化した。得られた試料ペレットを連続相と分散相に分離し、その質量比を表１、２に示した。さらに、分離した連続相の各分析値を表３、４に、分散相の各分析値を表５、６に示した。
【００４９】
【表１】

【００５０】
【表２】

【００５１】
【表３】

【００５２】
【表４】

【００５３】
【表５】

【００５４】
【表６】

【００５５】
なお、表１〜６の測定は以下の方法で行った。
（１）連続相と分散相の質量比の測定
あらかじめ質量測定しておいた試料ペレット（質量をＡとする）をメチルエチルケトン（ＭＥＫ）中で温度２３℃で２４時間攪拌し、その後遠心分離機でＭＥＫに対する不溶分の分離を実施し、遠心分離操作後３０分静置した。遠心分離機の操作条件は次の通りである。
温度：−９℃
回転数：２００００ｒｐｍ
時間：６０分
遠心分離させた溶液の上澄み液と沈殿物とを分離し、沈殿物を真空乾燥機で乾燥した後、質量測定して（質量をＢとする）次の数１１式、数１２式により連続相と分散相の質量比を求めた。
【００５６】
【数１１】

【数１２】

【００５７】
（２）連続相の重量平均分子量測定
前記の遠心分離させた溶液の上澄み液を分取しメタノールを加え、スチレン−（メタ）アクリル酸エステル系共重合体（連続相）を沈殿させた。この沈殿物を採取し、下記記載のＧＰＣ測定条件で測定した。
装置名：ＳＹＳＴＥＭ−２１ Ｓｈｏｄｅｘ（昭和電工社製）
カラム：ＰＬ ｇｅｌ ＭＩＸＥＤ−Ｂを３本直列
温度：４０℃
検出：示差屈折率
溶媒：テトラハイドロフラン
濃度：２質量％
検量線：標準ポリスチレン（ＰＳ）（ＰＬ社製）を用いて作製し、重量平均分子量はＰＳ換算値で表した。
【００５８】
（３）連続相の屈折率測定
先の重量平均分子量測定の前処理と同様の方法でスチレン−（メタ）アクリル酸エステル系共重合体からなる連続相を採取し、充分乾燥した後、プレス成形機により試験片（０．５ｍｍ厚み）を作製して、デジタル屈折計ＲＸ−２０００（ＡＴＡＧＯ社製）を用いて、温度２５℃で測定した。なお、接触液はヨウ化水銀カリウム飽和水溶液を使用した。
【００５９】
（４）連続相および分散相の構成単量体単位の測定
先の測定の前処理で得られたスチレン−（メタ）アクリル酸エステル系共重合体からなる連続相（ＭＥＫ可溶分）とグラフト共重合体からなる分散相（ＭＥＫ不溶分）とをそれぞれ重クロロホルムに溶解または膨潤させてＦＴ−ＮＭＲ（日本電子社製ＦＸ−９０Ｑ型）を用いて、構成単量体単位を求めた。
【００６０】
（５）分散相の屈折率
あらかじめ構成単量体の単独成分からなるポリマーの屈折率をデジタル屈折計ＲＸ−２０００（ＡＴＡＧＯ社製）を用いて温度２５℃で測定し数１３式の係数を求め、前記の方法により求めた組成比から次式により求めた。
【数１３】

（ｎは分散相の屈折率、［Ｂｄ］、［Ｓｔ］、［ＭＭＡ］はそれぞれ順にブタジエン、スチレン、メチルメタクリレートの単量体の組成比である。但し［Ｂｄ］＋［ＭＭＡ］＋［Ｓｔ］＝１である）
【００６１】
（６）分散相の体積平均粒子径および標準偏差
試料ペレット約１ｇをＮ，Ｎ−ジメチルホルムアミド（ＤＭＦ）１００ｇ中で２４時間撹拌し、さらにＤＭＦを加えて適当な濃度になるように希釈し、レーザー回折散乱法粒子径分布測定器（ＣＯＵＬＴＥＲ社ＬＳ２３０型）を使用して測定した。
【００６２】
また、得られた試料ペレットを用いて、下記の物性測定方法に従い各種物性測定を行った。測定値を表７、８に示した。
【００６３】
【表７】

【００６４】
【表８】

【００６５】
（１）アイゾット（Ｉｚｏｄ）衝撃強度
試料ペレットを東芝機械（株）社製射出成形機（ＩＳ−８０ＣＮＶ）を用いて、シリンダー温度２２０℃で成形し、１２７×６４×６．４ｍｍ厚の試験片を作成して、深さ２．５４ｍｍのノッチを入れ、ＡＳＴＭ Ｄ２５６に準拠して測定した（単位：Ｊ／ｍ）。
【００６６】
（２）メルトフローレート（ＭＦＲ）
試料ペレットを用いてＪＩＳ Ｋ−６８７４に準拠して、温度２２０℃、荷重９８．０７Ｎ／ｃｍ²の条件で測定した（単位：ｇ／１０分）。
【００６７】
（３）曲げ弾性率
試料ペレットを東芝機械（株）社製射出成形機（ＩＳ−８０ＣＮＶ）を用いて、シリンダー温度２２０℃で成形し、１２７×６４×６．４ｍｍ厚の試験片を作成して、ＡＳＴＭ Ｄ７９０に準拠して測定した（単位：ＭＰａ）。
【００６８】
（４）ロックウェル硬度
試料ペレットを東芝機械（株）社製射出成形機（ＩＳ−８０ＣＮＶ）を用いて、シリンダー温度２２０℃で成形し、１２７×６４×６．４ｍｍ厚の試験片を作成して、ＡＳＴＭ Ｄ７８５に準拠して測定した（Ｍスケール）。
【００６９】
（５）曇度
東芝機械（株）社製射出成形機（ＩＳ−５０ＥＰ）を用いて、試料ペレットをシリンダー温度２２０℃で成形し、５５×９０×３ｍｍ寸法の角板試験片を作成した。この試験片について、ＡＳＴＭ Ｄ１００３に準拠して測定した（単位：％）。
【００７０】
（６）落錘衝撃強度
東芝機械（株）社製射出成形機（ＩＳ−８０ＣＶＮ）を用いて、試料ペレットをシリンダー温度２２０℃で成形し、１２０×１２０×２ｍｍ寸法の角板試験片を作成した。この試験片について、ＪＩＳ Ｋ−７２１１に準拠して測定し、結果は５０％破壊エネルギーで示した（単位：Ｊ）。
【００７１】
（７）射出成形品の透明性
試料ペレットを東芝機械（株）社製射出成形機（ＩＳ−８０ＣＮＶ）を用いて、シリンダー温度２２０℃、金型温度５０℃、成形サイクル１９秒（冷却時間１０秒）の条件にて枡形の成形品を作成し、目視にて透明性を評価した。
◎・・光沢感があり、透明性良好。
○・・光沢感が若干劣るが、透明性は良好。
△・・部分的にうすく曇った感じがある。
×・・全体的にうすく曇った感じがある。
◎、○を合格と判定した。
【００７２】
本発明のゴム変性スチレン系樹脂組成物に係わる実施例は、いずれも透明性、耐衝撃性、剛性、表面硬度および成形加工性に優れていたが、本発明の条件に合わないゴム変性スチレン系樹脂組成物に係わる比較例では、透明性、耐衝撃性、剛性、表面硬度および成形加工性のうちいずれかの物性において劣るものであった。
【００７３】
【発明の効果】
本発明によれば、透明性、耐衝撃性、剛性、表面硬度および成形加工性に優れたゴム変性スチレン系樹脂組成物、並びに該樹脂組成物を用いて射出成形してなる射出成形品を提供することが出来る。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rubber-modified styrenic resin composition excellent in transparency, impact resistance, rigidity, surface hardness, and molding processability, and an injection-molded product formed by injection molding using the resin composition. is there.
[0002]
[Prior art]
Conventionally, two or more kinds of monomers selected from styrene, methyl methacrylate and acrylonitrile are emulsion-polymerized into a rubber-like polymer latex obtained by emulsion polymerization of a mixture of butadiene and styrene or acrylonitrile and a butadiene monomer. It is known that a thermoplastic resin composition excellent in impact resistance and transparency can be obtained by mixing the obtained MBS polymer with a rubber-modified styrene polymer (Japanese Patent Publication No. 46-32748). . However, although these thermoplastic resin compositions are certainly excellent in impact resistance, they have the disadvantage that they are easily damaged due to low surface hardness and that good transparency cannot be obtained depending on the injection molding conditions. It was.
[0003]
Furthermore, in recent years, the thickness of molded products has been reduced, and the demands for rigidity and molding processability have increased, and the thermoplastic resin compositions obtained by conventional techniques have not yet obtained satisfactory physical properties for these demands. Currently.
[0004]
[Problems to be solved by the invention]
In view of such a current situation, the present invention is a rubber-modified styrenic resin composition excellent in transparency, impact resistance, rigidity, surface hardness, and molding processability, and injection molded using the resin composition. An injection molded product is submitted.
[0005]
[Means for Solving the Problems]
As a result of intensive studies to solve such problems, the present inventors have obtained a continuous phase of a specific styrene- (meth) acrylate ester copolymer, a dispersed phase of a specific graft copolymer, In the rubber-modified styrenic resin composition composed of the present invention, it has been found that the above-mentioned problems can be solved, and the present invention has been completed.
[0006]
That is, the present invention relates to styrene comprising (I) a styrene monomer, a (meth) acrylic acid ester monomer, and a vinyl monomer copolymerizable with these monomers used as necessary. -60-90 mass% of continuous phase of (meth) acrylic acid ester copolymer, (II) rubber-like elastic body, styrene monomer, (meth) acrylic acid ester monomer, and if necessary In a rubber-modified styrenic resin composition comprising 40 to 10% by mass of a dispersed phase of a graft copolymer composed of a vinyl monomer copolymerizable with these monomers,
The volume average particle size of the dispersed phase is 0.3 to 0.6 μm, the toluene swelling ratio is 3 to 8 times, and the number 3 obtained from the weight average molecular weight (Mw) of the continuous phase and its constituent monomer units A rubber-modified styrenic resin composition in which X in the formula is in the range of Formula 4 and an injection-molded product thereof.
[0007]
[Equation 3]

[Expression 4]

[0008]
Preferably, in the rubber-modified styrene resin composition, a rubber having a difference in refractive index between the continuous phase of the styrene- (meth) acrylate ester copolymer and the dispersed phase of the graft copolymer of 0.005 or less. A modified styrenic resin composition and an injection-molded product thereof.
[0009]
More preferably, in the rubber-modified styrene resin composition, the rubber-modified styrene resin composition has a dispersed phase of the graft copolymer having a volume average particle diameter of 0.3 to 0.6 μm and a standard deviation of 0.08 to 0.2 μm. A styrene resin composition and an injection molded product thereof.
[0010]
Hereinafter, the present invention will be described in detail. The styrene- (meth) acrylate copolymer constituting the continuous phase of the rubber-modified styrene resin composition of the present invention is a styrene monomer, a (meth) acrylate monomer, and necessary It is a copolymer composed of vinyl monomers copolymerizable with these monomers.
[0011]
The graft copolymer constituting the dispersed phase of the rubber-modified styrene resin composition of the present invention is a rubber-like elastic body, a styrene monomer, a (meth) acrylic acid ester monomer, and necessary It is a copolymer obtained by grafting a styrene- (meth) acrylic acid ester copolymer composed of a vinyl monomer copolymerizable with these monomers.
[0012]
The styrenic monomers used in the continuous phase and dispersed phase of the present invention are styrene, α-methyl styrene, p-methyl styrene, o-methyl styrene, m-methyl styrene, ethyl styrene, pt-butyl styrene. Styrene is preferred. These styrenic monomers may be used alone or in combination of two or more.
[0013]
Examples of the (meth) acrylic acid ester monomer used in the present invention include methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, methyl acrylate, ethyl acrylate, n-butyl acrylate, 2 -Acrylic esters such as methyl hexyl acrylate, 2-ethyl hexyl acrylate, decyl acrylate and the like can be mentioned, and methyl methacrylate or n-butyl acrylate is preferable, and methyl methacrylate is particularly preferable. These (meth) acrylic acid ester monomers may be used alone or in combination of two or more.
[0014]
Furthermore, examples of vinyl monomers copolymerizable with these monomers used as needed include acrylic acid, methacrylic acid, acrylonitrile, methacrylonitrile, N-phenylmaleimide, N-cyclohexylmaleimide, and the like. .
[0015]
Examples of the rubber-like elastic body used in the present invention include polybutadiene, styrene-butadiene block copolymer, and styrene-butadiene random copolymer.
In order to obtain good impact resistance and transparency of the rubber-modified styrenic resin composition, the amount of styrene in the styrene-butadiene block copolymer or styrene-butadiene random copolymer is 60% by mass or less. preferable.
[0016]
The rubber-modified styrene resin composition of the present invention comprises 60 to 90% by mass of a styrene- (meth) acrylic acid ester copolymer continuous phase and 40 to 10% by mass of a graft copolymer dispersed phase. If the graft copolymer is less than 10% by mass, the impact resistance is insufficient, and if it exceeds 40% by mass, the rigidity and the surface hardness are inferior.
[0017]
The mass ratio of the continuous phase and the dispersed phase was measured by stirring the rubber-modified styrene resin composition (mass is A) in methyl ethyl ketone (MEK) at a temperature of 23 ° C. for 24 hours, and then centrifuge with respect to MEK. The insoluble matter is separated and vacuum-dried, and the mass is measured (mass is defined as B), and the following equations (5) and (6) are used.
[Equation 5]

[Formula 6]

[0018]
Further, the dispersed phase of the graft copolymer has a volume average particle size of 0.3 to 0.6 μm and a toluene swelling ratio of 3 to 8 times. If the volume average particle diameter is less than 0.3 μm, the impact resistance is insufficient, and if it exceeds 0.6 μm, the transparency is inferior. If the toluene swelling ratio is less than 3 times, the impact resistance is insufficient, and if it exceeds 8 times, the transparency and surface hardness are inferior, which is not preferable.
[0019]
The toluene swelling ratio of the dispersed phase was determined by swelling the dispersed phase separated from the rubber-modified styrenic resin composition (mass is C) in toluene at a temperature of 23 ° C. for 24 hours, and then filtering with a 150 mesh wire mesh. Then, the mass is immediately measured (mass is set to D), and obtained by the following equation (7).
[Expression 7]

[0020]
Furthermore, when transparency is particularly required and / or when practical strength typified by surface impact is particularly required, the volume average particle diameter is 0.3 to 0.6 μm, and the standard deviation is 0.00. It is preferable that it is 08-0.2 micrometer.
[0021]
Further, in the continuous phase of the styrene- (meth) acrylic acid ester copolymer, the X in the formula 8 obtained from the weight average molecular weight (Mw) and its constituent monomer units is in the range of the formula 9 is required. However, the weight average molecular weight of the continuous phase described here is a polystyrene-reduced weight average molecular weight obtained by measuring the MEK soluble content of the rubber-modified styrene resin composition by a gel permeation chromatography (GPC) method.
[0022]
[Equation 8]

[Equation 9]

When X is less than 100,000, the impact resistance is insufficient, and when it exceeds 180000, the molding processability is inferior.
[0023]
The rubber-modified styrenic resin composition of the present invention has a refractive index difference of 0.005 or less between a continuous phase composed of a styrene- (meth) acrylic ester copolymer and a dispersed phase of a graft copolymer. It is preferable to obtain good transparency.
[0024]
However, since it is difficult to actually measure the refractive index of the graft copolymer, the refractive index n of the graft copolymer is generally calculated by calculating the composition ratio of monomers constituting the polymer by composition analysis. The refractive index can be obtained by calculation using the equation (10).
[Expression 10]

That is, the composition of the graft copolymer is composed of an Am monomer, a Bm monomer, and a Cm monomer, and each mass ratio is X _A , X _B And X _C (However, when the mass ratio is X _A + X _B + X _C = 1), n _A Is the refractive index of the polymer composed of Am monomer, n _B Is the refractive index of the polymer consisting of Bm monomer, n _C Indicates the refractive index of a polymer composed of a Cm monomer, and is obtained by calculation by substituting it into the above equation (10).
[0025]
The amount of each monomer constituting the continuous phase styrene- (meth) acrylic acid ester copolymer is not particularly limited as long as the above-described conditions are satisfied. 20 to 70% by mass of units, 30 to 80% by mass of (meth) acrylic acid ester monomer units, and 0 to 10 vinyl monomer units copolymerizable with these monomers used as necessary. % By mass.
[0026]
Further, the amount of the rubber-like elastic body and each monomer constituting the graft copolymer of the dispersed phase is not particularly limited as long as the above-described conditions are satisfied, but the amount of the rubber-like elastic body is 30 to 80 parts by mass. Styrene monomer units 20 to 70% by mass, (meth) acrylic acid ester monomer units 30 to 80% by mass, and vinyl monomers copolymerizable with these monomers used as necessary A graft copolymer grafted with 20 to 70 parts by mass of a styrene- (meth) acrylic acid ester copolymer composed of 0 to 10% by mass of a monomer unit is preferably used.
[0027]
The rubber-modified styrenic resin composition of the present invention can be produced by known techniques such as bulk polymerization, solution polymerization, suspension polymerization, bulk-suspension polymerization, and emulsion polymerization. In addition, any of a batch polymerization method and a continuous polymerization method can be used.
[0028]
The rubber-modified styrenic resin composition of the present invention is added with known additives such as antioxidants, weathering agents, lubricants, plasticizers, colorants, antistatic agents, mineral oil and the like. You may mix | blend in the range which does not impair the performance of a thing.
[0029]
The rubber-modified styrenic resin composition of the present invention is not particularly limited with respect to compounding and melt extrusion, and a known method can be employed. For example, there is a method in which each raw material is uniformly mixed in advance with a tumbler, a Henschel mixer or the like, supplied to a single screw extruder or a twin screw extruder, melt kneaded, and then adjusted as pellets.
The rubber-modified styrenic resin composition of the present invention thus obtained can be processed into various molded products by methods such as injection molding, compression molding and extrusion molding, and can be put to practical use. The rubber-modified styrenic resin composition has excellent transparency, impact resistance, rigidity, surface hardness, and molding processability. Therefore, injection molding is performed by injection-molding the rubber-modified styrenic resin composition. The product is very practically superior.
[0030]
【Example】
EXAMPLES Next, although an Example demonstrates this invention further, this invention is not limited to these examples.
[0031]
First, it shows from manufacture of raw material resin.
(A) Production of styrene- (meth) acrylic ester copolymer
Reference Example 1: Styrene- (meth) acrylic ester copolymer A-1
In a 250 liter autoclave, 0.5 g of sodium dodecylbenzenesulfonate, 250 g of tricalcium phosphate, 41 kg of styrene, 56 kg of methyl methacrylate and 3 kg of acrylonitrile are added to 100 kg of pure water, and t-butylperoxyisobutyrate is used as a polymerization initiator. 100 g and t-dodecyl mercaptan 300 g were added, and the mixed solution was dispersed with stirring at a rotational speed of 150 rpm. The mixture was subjected to heat polymerization at a temperature of 90 ° C. for 8 hours and at 130 ° C. for 2.5 hours. After completion of the reaction, washing, dehydration and drying were performed to obtain a bead-shaped styrene- (meth) acrylic acid ester copolymer A-1.
[0032]
Reference Example 2: Styrene- (meth) acrylic ester copolymer A-2
In Reference Example 1, except that t-dodecyl mercaptan was changed to 700 g, it was produced in the same manner as styrene- (meth) acrylate copolymer A-1, and the bead-shaped styrene- (meth) acrylate copolymer was Polymer A-2 was obtained.
[0033]
Reference Example 3: Styrene- (meth) acrylic ester copolymer A-3
In a 250 liter autoclave, 0.5 g of sodium dodecylbenzenesulfonate, 250 g of tricalcium phosphate, 23 kg of styrene, 73 kg of methyl methacrylate and 4 kg of acrylonitrile are added to 100 kg of pure water, and t-butylperoxyisobutyrate is used as a polymerization initiator. 100 g and 700 g of t-dodecyl mercaptan were added, and the mixed solution was dispersed under stirring at a rotational speed of 150 rpm. The mixture was subjected to heat polymerization at a temperature of 90 ° C. for 8 hours and at 130 ° C. for 2.5 hours. After completion of the reaction, washing, dehydration and drying were performed to obtain a bead-shaped styrene- (meth) acrylic acid ester copolymer A-3.
[0034]
Reference Example 4: Styrene- (meth) acrylic ester copolymer A-4
In Reference Example 3, except that t-dodecyl mercaptan was changed to 300 g, it was produced in the same manner as styrene- (meth) acrylate copolymer A-3, and the bead-shaped styrene- (meth) acrylate copolymer was Polymer A-4 was obtained.
[0035]
(B) Manufacture of rubber-like elastic latex
Reference Example 5: Rubber-like elastic latex G-1
To an autoclave with a volume of 200 liters, 115 kg of pure water, 500 g of potassium oleate, 75 g of sodium pyrophosphate, 1.5 g of ferrous sulfate, 2.2 g of sodium ethylenediaminetetraacetate and 22 g of Rongalite were added and dissolved uniformly with stirring. Next, 12.5 kg of styrene, 37.5 kg of butadiene, 148 g of t-dodecyl mercaptan, 30 g of divinylbenzene and 96 g of diisopropylbenzene hydroperoxide were added, and the reaction was carried out at 50 ° C. for 16 hours with stirring to complete the polymerization. An elastic latex was obtained. After adding 45 g of sodium sulfosuccinate to the obtained rubber-like elastic latex and sufficiently stabilizing it, 0.2 wt% hydrochloric acid aqueous solution and 2 wt% caustic soda aqueous solution were passed through separate nozzles, and the pH of the latex was 8-9. The latex was coagulated and enlarged to obtain a rubber-like elastic latex G-1 having a volume average particle size of 0.42 μm.
[0036]
Reference Example 6: Rubber-like elastic latex G-2
In Reference Example 5, the rubber-like elastic latex G-2 was obtained in the same manner as the rubber-like elastic latex G-1 except that the volume-average particle size was changed to 0.63 μm by changing the conditions for agglomeration and enlargement. .
[0037]
Reference Example 7: Rubber-like elastic latex G-3
85 kg of pure water, 1200 g of potassium oleate, 200 g of potassium hydroxide and 50 g of potassium persulfate were added to an autoclave having a volume of 200 liters and dissolved uniformly with stirring. Next, 50 kg of butadiene, 100 g of t-dodecyl mercaptan, and 50 g of divinylbenzene were added, and the reaction was performed at 50 ° C. for 16 hours with stirring to complete the polymerization, thereby obtaining a rubber-like elastic latex. The obtained rubber-like elastic latex was coagulated and enlarged using a Menton Gorin type pressure coagulation enlargement machine to obtain a rubber-like elastic latex G-3 having a volume average particle size of 0.35 μm.
[0038]
Reference Example 8: Rubber-like elastic latex G-4
To an autoclave having a capacity of 200 liters, 56 kg of pure water, 400 g of potassium oleate, 1200 g of potassium rosinate, 1.2 kg of sodium carbonate and 400 g of potassium persulfate were added and dissolved uniformly with stirring. Next, 80 kg of butadiene and 400 g of t-dodecyl mercaptan were added, polymerization was carried out at 60 ° C. for 30 hours with stirring, the temperature was further raised to 70 ° C. and allowed to stand for 30 hours to complete the polymerization, and the volume average particle size was 0.34 μm. A rubbery elastic latex G-4 was obtained.
[0039]
Reference Example 9: Rubber-like elastic latex G-5
To an autoclave having a volume of 200 liters, 64 kg of pure water, 1680 g of potassium oleate, 160 g of potassium rosinate, 1.2 kg of sodium carbonate, 20 g of sodium bicarbonate and 400 g of potassium persulfate were added and dissolved uniformly with stirring. Next, 20 kg of styrene, 60 kg of butadiene, and 320 g of t-dodecyl mercaptan were added, polymerization was carried out at 55 ° C. for 16 hours with stirring, the temperature was further raised to 70 ° C. and left for 8 hours to complete the polymerization, and the volume average particle size was 0. A 19-μm rubbery elastic latex G-5 was obtained.
[0040]
(C) Production of graft copolymer-containing polymer
Reference Example 10: Graft copolymer-containing polymer B-1
30 kg of the rubber-like elastic latex G-1 of Reference Example 5 was weighed in terms of solid content, transferred to an autoclave with a volume of 200 L, 80 kg of pure water was added, and the temperature was raised to 50 ° C. in a nitrogen stream while stirring. To this was added 2 kg of pure water in which 1.25 g of ferrous sulfate, 2.5 g of sodium ethylenediaminetetraacetate and 100 g of Rongalite were dissolved, and a mixture consisting of 12.9 kg of styrene, 17.1 kg of methyl methacrylate, and 60 g of t-dodecyl mercaptan; A solution obtained by dispersing 120 g of diisopropylbenzene hydroperoxide in 8 kg of pure water containing 450 g of potassium oleate was separately added continuously over 6 hours. After completion of the addition, the temperature was raised to 70 ° C., 30 g of diisopropylbenzene hydroperoxide was further added, and the mixture was left for 2 hours to complete the polymerization.
An antioxidant is added to the obtained emulsion, the solid content is diluted to 15% by mass with pure water, the temperature is raised to 60 ° C., dilute sulfuric acid is added with vigorous stirring, and salting out is performed. The temperature was raised to 90 ° C. to solidify, followed by dehydration, washing with water and drying to obtain a powdered graft copolymer-containing polymer B-1.
[0041]
Reference Example 11: Graft copolymer-containing polymer B-2
In Reference Example 10, except that the rubber-like elastic latex was changed to the rubber-like elastic latex G-2, it was produced in the same manner as the graft copolymer-containing polymer B-1, and the powdered graft copolymer was contained. Polymer B-2 was obtained.
[0042]
Reference Example 12: Graft copolymer-containing polymer B-3
In Reference Example 10, the rubber-like elastic latex G-2 was changed to a combination of 15 kg of the rubber-like elastic latex G-2 in terms of solids and 15 kg of the rubber-like elastic latex G-5 in terms of solids. Produced in the same manner as the copolymer-containing polymer B-1, a powdery graft copolymer-containing polymer B-3 was obtained.
[0043]
Reference Example 13: Graft copolymer-containing polymer B-4
In Reference Example 10, except that the rubber-like elastic latex was changed to the rubber-like elastic latex G-5, it was produced in the same manner as the graft copolymer-containing polymer B-1, and the powdered graft copolymer was contained. Polymer B-4 was obtained.
[0044]
Reference Example 14: Graft copolymer-containing polymer B-5
30 kg of the rubber-like elastic latex G-3 of Reference Example 7 was weighed in terms of solid content, transferred to an autoclave with a volume of 200 L, 80 kg of pure water was added, and the temperature was raised to 50 ° C. in a nitrogen stream while stirring. To this was added 2 kg of pure water in which 1.25 g of ferrous sulfate, 2.5 g of sodium ethylenediaminetetraacetate and 100 g of Rongalite were dissolved, and a mixture consisting of 6.9 kg of styrene, 23.1 kg of methyl methacrylate, and 60 g of t-dodecyl mercaptan; A solution obtained by dispersing 120 g of diisopropylbenzene hydroperoxide in 8 kg of pure water containing 450 g of potassium oleate was separately added continuously over 6 hours. After completion of the addition, the temperature was raised to 70 ° C., 30 g of diisopropylbenzene hydroperoxide was further added, and the mixture was left for 2 hours to complete the polymerization.
An antioxidant is added to the obtained emulsion, the solid content is diluted to 15% by mass with pure water, the temperature is raised to 60 ° C., dilute sulfuric acid is added with vigorous stirring, and salting out is performed. The temperature was raised to 90 ° C. to solidify, followed by dehydration, washing with water, and drying to obtain a powdered graft copolymer-containing polymer B-5.
[0045]
Reference Example 15: Graft copolymer-containing polymer B-6
In Reference Example 14, it was produced in the same manner as the graft copolymer-containing polymer B-5 except that the rubber-like elastic latex was changed to the rubber-like elastic latex G-4, and the powdered graft copolymer contained Polymer B-6 was obtained.
[0046]
Reference Example 16: Graft copolymer-containing polymer B-7
In Reference Example 14, except that the rubber-like elastic latex G-3 was changed to a combination of 15 kg of the rubber-like elastic latex G-3 in terms of solids and 15 kg of the rubber-like elastic latex G-4 in terms of solids, as a rubbery elastic latex. Produced in the same manner as the copolymer-containing polymer B-5, a powdered graft copolymer-containing polymer B-7 was obtained.
[0047]
Reference Example 17: Graft copolymer-containing polymer B-8
In a 100 liter autoclave, 4 kg of a styrene-butadiene copolymer (25% styrene content, Toughden 2000 (trade name) manufactured by Asahi Kasei Co., Ltd.) was dissolved in a monomer mixture of 32.3 kg of styrene and 43.7 kg of methyl methacrylate. 32 g of benzoyl peroxide as a polymerization initiator and 160 g of t-dodecyl mercaptan as a chain transfer agent were added, the rotation speed of a stirring blade was set to 260 rpm, and the mixture was heated to 90 ° C. When the polymerization conversion rate reached 30% by mass, the bulk polymerization was stopped by cooling.
Next, 70 kg of the reaction mixture was transferred to an autoclave having a volume of 200 liters, and 140 g of dicumyl peroxide was newly added thereto as a polymerization initiator. To 100 kg of pure water, 0.5 g of sodium dodecylbenzenesulfonate and 350 g of tricalcium phosphate were added as suspension stabilizers, and the mixture was dispersed with stirring.
The reaction system was subjected to heat polymerization at a temperature of 100 ° C. for 2 hours, 115 ° C. for 3.5 hours, and 130 ° C. for 2.5 hours. After completion of the reaction, washing, dehydration and drying were carried out to obtain a bead-shaped graft copolymer-containing polymer B-8.
[0048]
Examples and comparative examples
The ratio (mass%) shown in Tables 1 and 2 of the styrene- (meth) acrylic acid ester copolymer produced in Reference Examples 1 to 4 and the graft copolymer-containing polymer produced in Reference Examples 10 to 17 After blending and mixing with a Henschel mixer, the mixture was melt-kneaded at a cylinder temperature of 220 ° C. with a twin-screw extruder (TEM-35B manufactured by Toshiba Machine Co., Ltd.) to be pelletized. The obtained sample pellets were separated into a continuous phase and a dispersed phase, and the mass ratios are shown in Tables 1 and 2. Furthermore, each analysis value of the separated continuous phase is shown in Tables 3 and 4, and each analysis value of the dispersed phase is shown in Tables 5 and 6.
[0049]
[Table 1]

[0050]
[Table 2]

[0051]
[Table 3]

[0052]
[Table 4]

[0053]
[Table 5]

[0054]
[Table 6]

[0055]
In addition, the measurement of Tables 1-6 was performed with the following method.
(1) Measurement of mass ratio of continuous phase and dispersed phase
A sample pellet (mass is A) that has been mass-measured in advance is stirred in methyl ethyl ketone (MEK) at a temperature of 23 ° C. for 24 hours, and then a centrifuge is used to separate insolubles from MEK, followed by centrifugation. It was left still for 30 minutes. The operating conditions of the centrifuge are as follows.
Temperature: -9 ° C
Rotational speed: 20000 rpm
Time: 60 minutes
The supernatant solution and the precipitate separated from the centrifuged solution are separated, and the precipitate is dried with a vacuum dryer, and then the mass is measured (mass is defined as B). And the mass ratio of the dispersed phase.
[0056]
[Expression 11]

[Expression 12]

[0057]
(2) Measurement of weight average molecular weight of continuous phase
The supernatant of the centrifuged solution was collected, methanol was added, and a styrene- (meth) acrylic acid ester copolymer (continuous phase) was precipitated. The precipitate was collected and measured under the GPC measurement conditions described below.
Device name: SYSTEM-21 Shodex (manufactured by Showa Denko)
Column: 3 series PL gel MIXED-B
Temperature: 40 ° C
Detection: Differential refractive index
Solvent: Tetrahydrofuran
Concentration: 2% by mass
Calibration curve: prepared using standard polystyrene (PS) (manufactured by PL), and the weight average molecular weight was expressed in terms of PS.
[0058]
(3) Refractive index measurement of continuous phase
A continuous phase composed of a styrene- (meth) acrylic acid ester copolymer is collected in the same manner as in the previous pretreatment for weight average molecular weight measurement, sufficiently dried, and then subjected to a test piece (0.5 mm thickness) by a press molding machine. ) And measured at a temperature of 25 ° C. using a digital refractometer RX-2000 (manufactured by ATAGO). The contact liquid was a saturated aqueous solution of potassium potassium iodide.
[0059]
(4) Measurement of constituent monomer units of continuous phase and dispersed phase
The continuous phase (MEK soluble component) made of the styrene- (meth) acrylic acid ester copolymer obtained by the pretreatment of the previous measurement and the dispersed phase (MEK insoluble component) made of the graft copolymer were respectively overlapped. The constituent monomer units were obtained by dissolving or swelling in chloroform and using FT-NMR (FX-90Q type, manufactured by JEOL Ltd.).
[0060]
(5) Refractive index of dispersed phase
The refractive index of a polymer composed of a single component of a constituent monomer is measured in advance at a temperature of 25 ° C. using a digital refractometer RX-2000 (manufactured by ATAGO) to obtain the coefficient of equation (13). It calculated | required by following Formula from ratio.
[Formula 13]

(N is the refractive index of the dispersed phase, and [Bd], [St], and [MMA] are the composition ratios of the monomers of butadiene, styrene, and methyl methacrylate, respectively. However, [Bd] + [MMA] + [St ] = 1
[0061]
(6) Volume average particle size and standard deviation of dispersed phase
About 1 g of the sample pellet is stirred in 100 g of N, N-dimethylformamide (DMF) for 24 hours, and further diluted with DMF to an appropriate concentration. A laser diffraction scattering particle size distribution analyzer (LS230, manufactured by COULTER) Type).
[0062]
Moreover, various physical property measurements were performed using the obtained sample pellets according to the following physical property measurement methods. The measured values are shown in Tables 7 and 8.
[0063]
[Table 7]

[0064]
[Table 8]

[0065]
(1) Izod impact strength
Sample pellets were molded at a cylinder temperature of 220 ° C. using an injection molding machine (IS-80CNV) manufactured by Toshiba Machine Co., Ltd., and a test piece 127 × 64 × 6.4 mm thick was prepared. A 54 mm notch was inserted and measured according to ASTM D256 (unit: J / m).
[0066]
(2) Melt flow rate (MFR)
Using sample pellets, temperature 220 ° C., load 98.07 N / cm according to JIS K-6874 ² (Unit: g / 10 minutes).
[0067]
(3) Flexural modulus
Sample pellets are molded at a cylinder temperature of 220 ° C. using an injection molding machine (IS-80CNV) manufactured by Toshiba Machine Co., Ltd., and a test piece of 127 × 64 × 6.4 mm thickness is prepared and conforms to ASTM D790 (Unit: MPa).
[0068]
(4) Rockwell hardness
Sample pellets were molded at a cylinder temperature of 220 ° C. using an injection molding machine (IS-80CNV) manufactured by Toshiba Machine Co., Ltd., and a test piece 127 × 64 × 6.4 mm thick was prepared and conformed to ASTM D785. (M scale).
[0069]
(5) Haze
Using an injection molding machine (IS-50EP) manufactured by Toshiba Machine Co., Ltd., a sample pellet was molded at a cylinder temperature of 220 ° C. to prepare a 55 × 90 × 3 mm size square plate test piece. About this test piece, it measured based on ASTM D1003 (unit:%).
[0070]
(6) Drop weight impact strength
Using an injection molding machine (IS-80CVN) manufactured by Toshiba Machine Co., Ltd., a sample pellet was molded at a cylinder temperature of 220 ° C. to prepare a square plate test piece having a size of 120 × 120 × 2 mm. About this test piece, it measured based on JISK-7111, and the result was shown by 50% fracture energy (unit: J).
[0071]
(7) Transparency of injection molded products
Sample pellets are molded into a bowl shape using an injection molding machine (IS-80CNV) manufactured by Toshiba Machine Co., Ltd. under conditions of a cylinder temperature of 220 ° C., a mold temperature of 50 ° C., and a molding cycle of 19 seconds (cooling time of 10 seconds). Articles were prepared and the transparency was visually evaluated.
◎ ・ ・ Glossy and good transparency.
○ ・ ・ Slightly inferior in glossiness but good in transparency.
△ ・ ・ Partial and slightly cloudy.
× · · There is a slightly cloudy feeling overall.
◎ and ○ were determined to be acceptable.
[0072]
Examples relating to the rubber-modified styrenic resin composition of the present invention were all excellent in transparency, impact resistance, rigidity, surface hardness and moldability, but did not meet the conditions of the present invention. In the comparative example concerning a resin composition, it was inferior in any physical property among transparency, impact resistance, rigidity, surface hardness, and moldability.
[0073]
【The invention's effect】
According to the present invention, there are provided a rubber-modified styrenic resin composition excellent in transparency, impact resistance, rigidity, surface hardness and molding processability, and an injection molded product formed by injection molding using the resin composition. I can do it.

Claims (3)

(I) Styrene- (meth) acryl comprising 20 to 70% by mass of styrene monomer units, 30 to 80% by mass of (meth) acrylic acid ester monomer units, and 0 to 10% by mass of acrylonitrile monomer units. 60 to 90% by mass of the continuous phase of the acid ester copolymer, and 30 to 80 parts by mass of the rubber-like elastic body of (II) polybutadiene or styrene-butadiene copolymer, and 20 to 70% by mass of the styrene monomer unit. The dispersion phase of the graft copolymer grafted with 20 to 70 parts by mass of a styrene- (meth) acrylic acid ester copolymer composed of 30 to 80% by mass of a (meth) acrylic acid ester monomer unit In a rubber-modified styrenic resin composition comprising:
1 g of a rubber-modified styrenic resin composition is stirred in 100 g of N, N-dimethylformamide (DMF) for 24 hours, further diluted by adding DMF, and a laser diffraction scattering method particle size distribution measuring instrument (COULTER LS230 type). The rubber-modified styrenic resin composition was stirred in methyl ethyl ketone (MEK) at a temperature of 23 ° C. for 24 hours with a volume average particle size of the dispersed phase measured by use of 0.3 to 0.6 μm and then centrifuged. After separating the insoluble matter with respect to MEK and vacuum drying, the disperse phase (mass is C) was swollen in toluene at a temperature of 23 ° C. for 24 hours, then filtered through a 150 mesh wire net and immediately mass-measured ( mass and D), toluene swelling capacity was determined (D / C) is the 3 to 5.9-fold, and obtains a weight-average molecular weight of the continuous phase (Mw) to from its constituent monomer units Rubber-modified styrenic resin composition which equation (1) of X is characterized in that the range of equation (2) to be.

   The rubber-modified styrenic resin composition according to claim 1, wherein the dispersed phase of the graft copolymer has a volume average particle size of 0.3 to 0.6 µm and a standard deviation of 0.08 to 0.2 µm. object. An injection-molded article obtained by injection-molding the rubber-modified styrenic resin composition according to claim 1 or 2 .