JP3595869B2 - Styrene copolymer, method for producing the same, and molded article - Google Patents
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Description
【０００１】
【発明の属する技術分野】
本発明は、スチレン系化合物および複数のビニル基を有する化合物のスチレン系共重合体、その製造方法及び成形体に関するものである。
【０００２】
【従来の技術】
スチレン系樹脂は、剛性があり、寸法安定性に優れ、かつ廉価であることから、成形用途に広く使用されている。近年、射出成形、押出成形、発泡成形の各種用途においては高強度化の要求が益々強くなっている。かかる要求に応える試みとして、樹脂の分子量を高くし、強度を高める方法が提案されている。しかしながら、この方法には樹脂の流動性が低下し成形が困難となるもといった問題があった。また、樹脂の分子量を低下させずに流動性を高める方法として、樹脂にミネラルオイルなどの可塑剤を添加して用いる方法がある。しかしながら、この方法には、可塑剤により樹脂の耐熱性及び機械的強度が低下するという問題があった。
このように流動性を維持したまま、樹脂の耐熱性および機械的強度を高くする方法として、ジビニルべンゼンのような複数のビニル基を有する化合物と共重合する方法が、特開昭８−４５５９０号公報、特開平２−１７０８６６号公報、特開平７−１６６０１３号公報に開示されている。
しかしながら、これらの方法では、分子量が高くなるとともに分子量分布も広くなり、また分岐構造は高分子量成分のみに含有される。また、得られた共重合体には超高分子量成分や低分子量成分が含まれる。超高分子量成分が含まれるため成形品の透明性が劣り、低分子量成分が含まれるためにクリープ特性が劣るという問題があった。また、スチレン系化合物と複数のビニル基を有する化合物を共に反応系に連続的に添加する方法、いわゆる連続塊状重合法において、未反応の複数のビニル基を有する化合物が多量に残存し、重合槽あるいはプロセス配管内にゲル付着物が発生する問題があった。またリサイクルソルベント中にも未反応の複数のビニル基を有する化合物が多量に残存するため、長期間の放置によりゲルが発生する恐れがあり、長期連続運転が困難となる問題があった。
【０００３】
【発明が解決しようとする課題】
かかる状況において、本発明が解決しようとする課題は、スチレン系化合物および複数のビニル基を有する化合物の共重合体であって、分子量分布が狭く、したがって、超高分子量成分や低分子量成分が含まれず、また分岐構造は高分子量成分のみに片寄って含有されない、スチレン系共重合体、その製造方法および成形体を提供する点に存する。
【０００４】
【課題を解決するための手段】
本発明者らは上記の課題を解決すべく鋭意検討した結果、本発明に到達したものである。
すなわち、本発明のひとつはスチレン系化合物および複数のビニル基を有する化合物の共重合体であって、重量平均分子量（Ｍｗ）が１０万〜５０万であり、数平均分子量（Ｍｎ）が５万〜４０万であり、分子量分布（Ｍｗ／Ｍｎ）が１．５以上２．５未満であり、数平均分子量（Ｍｎ）、重量平均分子量（Ｍｗ）およびｚ平均分子量（Ｍｚ）における、スチレンモノマー１０００ユニット当たりの分岐数である分岐度（λ）が等しく０．１以上１０未満であることを特徴とし、
ラジカル捕捉剤の存在下、スチレン系化合物および複数のビニル基を有する化合物を共重合させるに際し、
（１）重合される化合物に対する複数のビニル基を有する化合物濃度（Ｄ；ｍｏｌ％）およびラジカル捕捉剤濃度（Ｃ；ｍｏｌ％）が
【数１】
３．０×１０-3≦Ｃ≦１．０×１０-1
【数２】
０．２≦Ｃ／Ｄ≦４．０
となる範囲で、
（２）重合温度が１００〜１６０℃で、
（３）重合転化率が４０〜８０％となるまで重合を行う、
ことによって製造されたスチレン系共重合体である。
本発明の他のひとつは、ラジカル捕捉剤の存在下、スチレン系化合物および複数のビニル基を有する化合物を共重合させるスチレン系重合体の製造方法であって、
（１）重合される化合物に対する複数のビニル基を有する化合物濃度（Ｄ；ｍｏｌ％）およびラジカル捕捉剤濃度（Ｃ；ｍｏｌ％）が
【数１】
３．０×１０-3≦Ｃ≦１．０×１０-1
【数２】
０．２≦Ｃ／Ｄ≦４．０
となる範囲で、
（２）重合温度が１００〜１６０℃で、
（３）重合転化率が４０〜８０％となるまで重合を行う、
ことを特徴とするスチレン系共重合体の製造方法である。
本発明の他のひとつは、上記のスチレン系共重合体を射出成形、押出成形または発泡成形することにより得られることを特徴とする成形体である。
以下、本発明を詳細に説明する。
【０００５】
【発明の実施の形態】
本発明で用いられるスチレン系化合物としては、スチレン、α−メチルスチレンなどのα−置換アルキルスチレン、ｐ−メチルスチレンなどの核置換アルキルスチレンなどが挙げられる。
また、本発明の製造方法においては、上記のスチレン系化合物と共に、スチレン系化合物と共重合可能な化合物、たとえばアクリロニトリル、メタクリロニトリル、メタクリル酸、アクリル酸、メタクリル酸メチル、アクリル酸メチルなどのエステル誘導体、などのビニルモノマー、更には無水マレイン酸、マレイミド、核置換マレイミドなどを、重合される化合物に対して５０重量％未満の範囲で併用してもよい。
【０００６】
本発明で用いられる複数のビニル基を有する化合物として、ジビニルベンゼン、エチレングリコールジメタクリレートなどを挙げることができる。
【０００７】
本発明で用いるラジカル捕捉剤とは、ポリマーの成長ラジカルと容易に結合、解離でき、平衡状態をとり得るような化合物であり、種々の安定フリーラジカル剤を使用することができる。
【０００８】
本発明で用いるラジカル捕捉剤としては、例えば、２，２，６，６−テトラメチル−１−ピペリジニルオキシ（以下、ＴＥＭＰＯと略する。）、４−アミノ−ＴＥＭＰＯ、４−ヒドロキシ−ＴＥＭＰＯ、４−オキソ−ＴＥＭＰＯなどのＴＥＭＰＯ誘導体、４，４−ジメチル−３−オキサゾリニルオキシやその誘導体、２，２，５，５−テトラメチル−１−ピロリジニルオキシやその誘導体、フェニル−ｔ−ブチルニトロキシド、２，２−ジ（４−ｔ−オクチルフェニル）−１−ピクリルヒドラジル（ＤＰＰＨ）等の安定フリーラジカル等がある。
これらの中でも２，２，６，６−テトラメチル−１−ピペリジニルオキシ（ＴＥＭＰＯ）が好ましい。
重合される化合物に対する複数のビニル基を有する化合物濃度（Ｄ；ｍｏｌ％）およびラジカル捕捉剤濃度（Ｃ；ｍｏｌ％）が
【数１】
３．０×１０-3≦Ｃ≦１．０×１０-1
【数２】
０．２≦Ｃ／Ｄ≦４．０
となる範囲で、ラジカル捕捉剤を添加する必要がある。Ｃが過小である場合は、得られた共重合体の分子量分布は広く、超高分子量成分をもち、分岐構造は高分子量成分のみにしか導入されない。また、連続塊状重合プロセスにおいてゲル発生の恐れがある。Ｃが過大である場合は、重合が進まず、分子量が低いものしか得られず、樹脂として使用できない。Ｃ／Ｄが過小である場合は、得られた共重合体の分子量分布は広く、超高分子量成分をもち、分岐構造は高分子量成分のみにしか導入されない。また、連続塊状重合プロセスにおいてゲル発生の恐れがある。Ｃ／Ｄが過大である場合は、分岐構造を含有した共重合体が得られない。
重合温度は１００〜１６０℃、好ましくは１００〜１５０℃、更に好ましくは１１０℃〜１４０℃の範囲で重合を行う必要がある。重合温度が低いと重合が進まず、共重合体の分子量が低いものしか得られず、樹脂として使用できない。重合温度が高い場合、得られた共重合体の分子量分布は広く、均一に分岐構造を含有した共重合体が得られない。
重合転化率は４０〜８０％、好ましくは５０〜７０％となるまで重合を行う必要がある。重合転化率が小さい場合、共重合体の分子量は低いものしか得られず、樹脂として使用できない。重合転化率が大きくなるまで重合を続ける場合、時間当たりの共重合体生成量が小さく、生産性に劣る。
【０００９】
本発明で用いるラジカル捕捉剤は、本発明の範囲でスチレン系化合物と予め混合して用いてもよいし、重合槽に添加することもできる。
【００１０】
本発明のスチレン系重合体の重合方法としては懸濁重合、乳化重合、塊状重合法を用いることができる。重合槽としては、完全混合型撹拌重合槽、プラグフロータイプの満液型（縦型又は横型）、静的混合管型重合槽又はこれらの重合槽を組み合わせて用いることができる。
【００１１】
重合方法として熱重合法あるいは開始剤を用いる重合法であることが好ましい。使用可能な開始剤としては、各種の単官能及び多官能過酸化物、アゾ系開始剤などを用いることが望ましい。
【００１２】
本発明のスチレン系共重合体は、その重量平均分子量（Ｍｗ）が１０万〜５０万であり、数平均分子量が５万〜４０万であり、分子量分布（Ｍｗ／Ｍｎ）が１．５以上２．５未満であり、分子鎖末端の一部にラジカル補捉剤を含有し、数平均分子量（Ｍｎ）、重量平均分子量（Ｍｗ）およびｚ平均分子量（Ｍｚ）における、スチレンモノマー１０００ユニット当たりの分岐数である分岐度（λ）が等しく０．１以上１０未満であることを特徴とするスチレン系共重合体である。
ここで、スチレンモノマー１０００ユニット当たりの分岐数である分岐度（λ）は、検出器として示差屈折率計とオンライン粘度計とを備えたゲルパーミエーションクロマトグラフィー（ＧＰＣ）を用いた、いわゆるＧＰＣ−粘度法で測定することができる。スチレンモノマー１０００ユニット当たりの分岐数である分岐度（λ）は次式で求められる。
［ＩＶ（Ｍ）／ＩＶＬ（Ｍ）］2/3 ＝［（１＋Ｂｎ（Ｍ）／７）1/2＋４／９・Ｂｎ（Ｍ）］-1/2
λ（Ｍ）＝Ｂｎ（Ｍ）×Ｍｓｔ×１０００／Ｍ
ここで、Ｍは共重合体のひとつの分子鎖の分子量、ＩＶ（Ｍ）は分子量Ｍである本発明の共重合体分子鎖の極限粘度、ＩＶＬ（Ｍ）は本発明共重合体と同じ分子量Ｍをもつ直鎖状ポリスチレン標準ポリマーの極限粘度である。Ｍｓｔはスチレンモノマーの分子量であり、１０４である。また、Ｂｎ（Ｍ）は分子量Ｍである本発明の共重合体分子鎖に含まれる分岐点の数である。ＧＰＣ−粘度法では本発明の共重合体の各分子量ＭにおけるＩＶ（Ｍ）およびＩＶＬ（Ｍ）を測定し、上記式から、Ｂｎ（Ｍ）を求め、λ（Ｍ）を求めることができる。λ（Ｍｎ）、λ（Ｍｗ）、λ（Ｍｚ）とはそれぞれ、平均分子量Ｍｎ、Ｍｗ、Ｍｚと同じ分子量を持った分子鎖におけるλ値である。
本発明のスチレン系共重合体は、分子鎖末端の一部にラジカル捕捉剤に基づく基を含有する。これはその重合過程において、生成したポリマーラジカルの一部はラジカル補足剤と結合し、重合が停止するためである。ポリマー鎖にラジカル補足剤による基が含有しているかを判別する方法としては、例えば、高分解能ＮＭＲ法や熱分解ＧＣ−ＭＳ法などが挙げられる。
【００１３】
本発明のスチレン系共重合体は、該スチレン系共重合体を２０〜９９．９９５重量％含み、該スチレン系共重合体以外の成分として、他のスチレン系重合体を８０〜０．００５重量％含む樹脂組成物とすることができる。他のスチレン系重合体として、一般ポリスチレン（ＧＰＰＳ）、ゴム変性ポリスチレン（ＨＩＰＳ）、スチレン−ブタジエンブロック共重合体（ＳＢ、ＳＢＳ）及びその水添物（ＳＥＢＳ）などの耐衝撃性改良剤などがあげられる。
本発明のスチレン系共重合体には、ミネラルオイルなどの可塑剤、離型剤、滑剤、帯電防止剤、酸化防止剤、熱安定剤、紫外線吸収剤、難燃剤、抗菌剤、顔料、染料など通常の添加剤を配合することができる。
本発明のスチレン系共重合体に、該共重合体以外の成分を添加する方法は、本発明のスチレン系共重合体を製造する際に、重合系にそれらを添加して製造することができる。また、該共重合体と共重合体以外の成分を溶融混練することで製造することができる。
【００１４】
本発明のスチレン系共重合体は、射出成形用途、押出成形用途、または発泡成形用途などに使用できる。例えば、テレビなどの家電製品、ＯＡ機器のハウジング、ヨーグルトカップなどの射出成形体、食品用ボトルや事務機器用パネルなどのブロー成形品、冷蔵庫内装材などのシート成形品、ＰＳＰラミネート用インフレーションフィルムや食品包装用二軸延伸フィルムなどの押出成形体、発泡ポリスチレンシート、発泡ボード、ビーズ発泡などの発泡成形体に使用できる。
【００１５】
【実施例】
以下、実施例により本発明を説明するが、本発明はこれら実施例に限定されるものではない。
実施例及び比較例で用いた測定方法は、次のとおりである。
（１）重合転化率
重合で得られた重合溶液試料０． ５ｇを精秤し、メチルエチルケトンに溶解させた溶液を、過剰のメタノール溶液中に滴下して、沈殿させて、ろ過して得られたものを７０℃で２時間真空乾燥させ乾燥後重量を０．５ｇで割った値を百分率で表したものを重合転化率とした。
（２）ゲルの有無、重量平均分子量（Ｍｗ）および分子量分布（Ｍｗ／Ｍｎ）
（１）で乾燥したポリマーサンプルの濃度が約０． ５ｍｇ／ｍｌになるように、テトラヒドロフラン溶剤に溶解させ、ゲルの有無を目視観察した。ゲル発生した場合は、溶液が白濁する。 溶解液をろ過後、ゲルパーミエーションクロマトグラフィー（ＧＰＣ）を用いて測定した。ここでこのＧＰＣは検出器として示差屈折率計を備えたものであり、重量平均分子量（Ｍｗ）および分子量分布（Ｍｗ／Ｍｎ）は、単分散ポリスチレンを用いて求めた検量線によって算出した。
【００１６】
実施例１〜３
スチレンと、複数のビニル基を有する化合物としてジビニルベンゼン（ｍ−、ｐ−混合体）、ラジカル捕捉剤として２， ２， ６， ６−テトラメチル−１−ピペリジニルオキシ（ＴＥＭＰＯ）を用いて表１に示すような組成に調合した溶液を表１に示す重合温度で重合を行った。測定結果を表１に示す。
【００１７】
比較例１〜７
スチレンと、複数のビニル基を有する化合物としてジビニルベンゼン（ｍ−、ｐ−混合体）、ラジカル捕捉剤として２， ２， ６， ６−テトラメチル−１−ピペリジニルオキシ（ＴＥＭＰＯ）を用いて表２，３に示すような組成に調合した溶液を表２，３に示す重合温度で重合を行った。測定結果を表２，３に示す。
【００１８】
【表１】
【表２】
【００２０】
【表３】
【００２１】
【発明の効果】
本発明のスチレン系共重合体は、スチレン系化合物および複数のビニル基を有する化合物の共重合体であって、分子量分布が狭く、したがって、超高分子量成分や低分子量成分が含まれず、また分岐構造は高分子量成分のみに片寄って含有されない。
また、本発明の、スチレン系化合物および複数のビニル基を有する化合物を共重合させるスチレン系共重合体の製造方法によれば、製造プラントにおけるゲル発生を抑制し、連続塊状重合法による製造を安定的に実施することができる。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a styrene-based copolymer of a styrene-based compound and a compound having a plurality of vinyl groups, a method for producing the same, and a molded article.
[0002]
[Prior art]
Styrene-based resins are widely used for molding because of their rigidity, excellent dimensional stability, and low cost. In recent years, there has been an increasing demand for higher strength in various uses such as injection molding, extrusion molding and foam molding. As an attempt to meet such a demand, a method has been proposed in which the molecular weight of the resin is increased to increase the strength. However, this method has a problem that the fluidity of the resin is reduced and molding becomes difficult. Further, as a method of increasing the fluidity without lowering the molecular weight of the resin, there is a method of adding a plasticizer such as mineral oil to the resin and using the resin. However, this method has a problem that heat resistance and mechanical strength of the resin are reduced by the plasticizer.
As a method for increasing the heat resistance and mechanical strength of a resin while maintaining the fluidity, a method of copolymerizing with a compound having a plurality of vinyl groups such as divinylbenzene is disclosed in JP-A-8-45590. And Japanese Patent Application Laid-Open Nos. 2-170866 and 7-166013.
However, in these methods, the molecular weight distribution increases as the molecular weight increases, and the branched structure is contained only in the high molecular weight component. Further, the obtained copolymer contains an ultrahigh molecular weight component and a low molecular weight component. There was a problem that the molded article had poor transparency due to the inclusion of the ultrahigh molecular weight component, and the creep properties were poor due to the inclusion of the low molecular weight component. In addition, in a method of continuously adding a styrene compound and a compound having a plurality of vinyl groups together to a reaction system, a so-called continuous bulk polymerization method, a large amount of an unreacted compound having a plurality of vinyl groups remains in a polymerization tank. Alternatively, there is a problem that gel deposits are generated in the process pipe. In addition, since a large amount of the unreacted compound having a plurality of vinyl groups remains even in the recycled solvent, a gel may be generated when left for a long period of time, and there is a problem that long-term continuous operation becomes difficult.
[0003]
[Problems to be solved by the invention]
In such a situation, the problem to be solved by the present invention is a copolymer of a styrene compound and a compound having a plurality of vinyl groups, which has a narrow molecular weight distribution, and therefore contains an ultrahigh molecular weight component and a low molecular weight component. Another object of the present invention is to provide a styrene-based copolymer, a method for producing the same, and a molded article, wherein the styrene-based copolymer does not have a branched structure and is not contained only in a high molecular weight component.
[0004]
[Means for Solving the Problems]
The present inventors have intensively studied to solve the above-mentioned problems, and as a result, have reached the present invention.
That is, one of the present invention is a copolymer of a styrene compound and a compound having a plurality of vinyl groups, the weight average molecular weight (Mw) is 100,000 to 500,000, and the number average molecular weight (Mn) is 50,000. Styrene monomer having a molecular weight distribution (Mw / Mn) of 1.5 or more and less than 2.5, and a number average molecular weight (Mn), a weight average molecular weight (Mw) and a z average molecular weight (Mz) of 1000 The number of branches (λ), which is the number of branches per unit, is equal to or greater than 0.1 and less than 10 ,
When copolymerizing a styrene compound and a compound having a plurality of vinyl groups in the presence of a radical scavenger,
(1) The concentration of the compound having a plurality of vinyl groups (D; mol%) and the concentration of the radical scavenger (C; mol%) with respect to the compound to be polymerized are as follows:
3.0 × 10 −3 ≦ C ≦ 1.0 × 10 −1
(Equation 2)
0.2 ≦ C / D ≦ 4.0
Within the range
(2) When the polymerization temperature is 100 to 160 ° C,
(3) Polymerization until the polymerization conversion rate becomes 40 to 80%.
This is a styrene-based copolymer produced by the above method.
Another one of the present invention is a method for producing a styrene polymer in which a styrene compound and a compound having a plurality of vinyl groups are copolymerized in the presence of a radical scavenger,
(1) The concentration of the compound having a plurality of vinyl groups (D; mol%) and the concentration of the radical scavenger (C; mol%) with respect to the compound to be polymerized are as follows:
3.0 × 10 −3 ≦ C ≦ 1.0 × 10 −1
(Equation 2)
0.2 ≦ C / D ≦ 4.0
Within the range
(2) When the polymerization temperature is 100 to 160 ° C,
(3) Polymerization until the polymerization conversion rate becomes 40 to 80%.
A method for producing a styrenic copolymer characterized by the above-mentioned.
Another aspect of the present invention is a molded article obtained by injection molding, extrusion molding, or foam molding of the styrene-based copolymer.
Hereinafter, the present invention will be described in detail.
[0005]
BEST MODE FOR CARRYING OUT THE INVENTION
Examples of the styrene compound used in the present invention include styrene, α-substituted alkylstyrene such as α-methylstyrene, and nucleus-substituted alkylstyrene such as p-methylstyrene.
Further, in the production method of the present invention, together with the styrene-based compound, a compound copolymerizable with the styrene-based compound, for example, acrylonitrile, methacrylonitrile, methacrylic acid, acrylic acid, methyl methacrylate, ester such as methyl acrylate A vinyl monomer such as a derivative, and furthermore, maleic anhydride, maleimide, nucleus-substituted maleimide and the like may be used together in an amount of less than 50% by weight based on the compound to be polymerized.
[0006]
Examples of the compound having a plurality of vinyl groups used in the present invention include divinylbenzene, ethylene glycol dimethacrylate, and the like.
[0007]
The radical scavenger used in the present invention is a compound that can easily bond to and dissociate from the growing radical of the polymer and can take an equilibrium state, and various stable free radical agents can be used.
[0008]
Examples of the radical scavenger used in the present invention include 2,2,6,6-tetramethyl-1-piperidinyloxy (hereinafter abbreviated as TEMPO), 4-amino-TEMPO, and 4-hydroxy-TEMPO. , TEMPO derivatives such as 4-oxo-TEMPO, 4,4-dimethyl-3-oxazolinyloxy and its derivatives, 2,2,5,5-tetramethyl-1-pyrrolidinyloxy and its derivatives, phenyl- There are stable free radicals such as t-butyl nitroxide and 2,2-di (4-t-octylphenyl) -1-picrylhydrazyl (DPPH).
Among these, 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) is preferred.
The concentration of the compound having a plurality of vinyl groups with respect to the compound to be polymerized (D; mol%) and the concentration of the radical scavenger (C; mol%)
(Equation 1)
3.0 × 10 −3 ≦ C ≦ 1.0 × 10 −1
(Equation 2)
0.2 ≦ C / D ≦ 4.0
It is necessary to add a radical scavenger in the range as follows. When C is too small, the molecular weight distribution of the obtained copolymer is wide, has an ultrahigh molecular weight component, and the branched structure is introduced only into the high molecular weight component. Also, there is a risk of gel formation in the continuous bulk polymerization process. When C is excessively large, polymerization does not proceed, and only those having a low molecular weight are obtained, and cannot be used as a resin. When C / D is too small, the molecular weight distribution of the obtained copolymer is wide, has an ultrahigh molecular weight component, and the branched structure is introduced only into the high molecular weight component. Also, there is a risk of gel formation in the continuous bulk polymerization process. When C / D is too large, a copolymer containing a branched structure cannot be obtained.
The polymerization temperature must be in the range of 100 to 160 ° C, preferably 100 to 150 ° C, and more preferably 110 to 140 ° C. If the polymerization temperature is low, the polymerization does not proceed, and only a copolymer having a low molecular weight is obtained, and cannot be used as a resin. When the polymerization temperature is high, the molecular weight distribution of the obtained copolymer is wide, and a copolymer having a uniform branched structure cannot be obtained.
It is necessary to carry out the polymerization until the polymerization conversion reaches 40 to 80%, preferably 50 to 70%. When the polymerization conversion is low, only a low molecular weight copolymer can be obtained and cannot be used as a resin. When the polymerization is continued until the polymerization conversion rate increases, the amount of the copolymer produced per hour is small, and the productivity is poor.
[0009]
The radical scavenger used in the present invention may be used as a mixture with a styrene compound in advance within the scope of the present invention, or may be added to a polymerization tank.
[0010]
As the polymerization method for the styrene polymer of the present invention, suspension polymerization, emulsion polymerization, or bulk polymerization can be used. As the polymerization tank, a complete mixing type stirring polymerization tank, a plug flow type full type (vertical or horizontal type), a static mixing tube type polymerization tank, or a combination of these polymerization tanks can be used.
[0011]
The polymerization method is preferably a thermal polymerization method or a polymerization method using an initiator . As the initiator that can be used, it is desirable to use various monofunctional and polyfunctional peroxides, azo-based initiators, and the like.
[0012]
The styrene copolymer of the present invention has a weight average molecular weight (Mw) of 100,000 to 500,000, a number average molecular weight of 50,000 to 400,000, and a molecular weight distribution (Mw / Mn) of 1.5 or more. It is less than 2.5, contains a radical scavenger at a part of the molecular chain terminal, and has a number average molecular weight (Mn), a weight average molecular weight (Mw) and a z average molecular weight (Mz) per 1000 units of styrene monomer. A styrene-based copolymer, wherein the degree of branching (λ), which is the number of branches, is equal to or greater than 0.1 and less than 10 .
Here, the degree of branching (λ), which is the number of branches per 1000 units of styrene monomer, is a so-called GPC- using a gel permeation chromatography (GPC) equipped with a differential refractometer and an online viscometer as a detector. It can be measured by a viscosity method. The degree of branching (λ), which is the number of branches per 1000 units of styrene monomer, is determined by the following equation.
[IV (M) / IVL (M)] 2/3 = [(1 + Bn (M) / 7) 1/2 + 4/9 · Bn (M)] −1/2
λ (M) = Bn (M) × Mst × 1000 / M
Here, M is the molecular weight of one molecular chain of the copolymer, IV (M) is the intrinsic viscosity of the molecular chain of the copolymer of the present invention having a molecular weight of M, and IVL (M) is the same molecular weight as the copolymer of the present invention. It is the intrinsic viscosity of a linear polystyrene standard polymer having M. Mst is the molecular weight of the styrene monomer and is 104. Bn (M) is the number of branch points contained in the molecular chain of the copolymer having a molecular weight M of the present invention. In the GPC-viscosity method, IV (M) and IVL (M) at each molecular weight M of the copolymer of the present invention are measured, Bn (M) is determined from the above equation, and λ (M) can be determined. λ (Mn), λ (Mw), and λ (Mz) are λ values in a molecular chain having the same molecular weight as the average molecular weights Mn, Mw, and Mz, respectively.
The styrenic copolymer of the present invention contains a group based on a radical scavenger at a part of the molecular chain terminal. This is because, during the polymerization process, a part of the generated polymer radicals binds to the radical scavenger, and the polymerization stops. Examples of a method for determining whether a group due to a radical scavenger is contained in the polymer chain include a high-resolution NMR method and a pyrolysis GC-MS method.
[0013]
The styrene-based copolymer of the present invention contains 20 to 99.995% by weight of the styrene-based copolymer, and contains 80 to 0.005% by weight of another styrene-based polymer as a component other than the styrene-based copolymer. % Of the resin composition. Other styrene-based polymers include impact modifiers such as general polystyrene (GPPS), rubber-modified polystyrene (HIPS), styrene-butadiene block copolymers (SB, SBS) and their hydrogenated products (SEBS). can give.
The styrenic copolymer of the present invention includes plasticizers such as mineral oil, release agents, lubricants, antistatic agents, antioxidants, heat stabilizers, ultraviolet absorbers, flame retardants, antibacterial agents, pigments, dyes, etc. Conventional additives can be blended.
The method of adding components other than the copolymer to the styrene copolymer of the present invention can be produced by adding them to the polymerization system when producing the styrene copolymer of the present invention. . Further, it can be produced by melt-kneading the copolymer and components other than the copolymer.
[0014]
The styrene copolymer of the present invention can be used for injection molding, extrusion molding, foam molding, and the like. For example, home appliances such as televisions, housings for OA equipment, injection molded articles such as yogurt cups, blow molded articles such as food bottles and office equipment panels, sheet molded articles such as refrigerator interior materials, blown film for PSP lamination, It can be used for extruded articles such as biaxially stretched films for food packaging, foamed articles such as expanded polystyrene sheets, foamed boards, and bead foams.
[0015]
【Example】
Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these examples.
The measuring methods used in the examples and comparative examples are as follows.
(1) Polymerization conversion ratio Polymer solution sample obtained by polymerization 5 g was precisely weighed, a solution dissolved in methyl ethyl ketone was added dropwise to an excess methanol solution to cause precipitation, and the resultant obtained by filtration was vacuum-dried at 70 ° C. for 2 hours. The value obtained by dividing the value obtained by dividing by 5 g as a percentage was defined as the polymerization conversion rate.
(2) Presence of gel, weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn)
The concentration of the polymer sample dried in (1) is about 0.5. It was dissolved in a tetrahydrofuran solvent so as to have a concentration of 5 mg / ml, and the presence or absence of a gel was visually observed. If a gel occurs, the solution becomes cloudy. After the solution was filtered, the solution was measured using gel permeation chromatography (GPC). Here, this GPC was equipped with a differential refractometer as a detector, and the weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) were calculated by a calibration curve obtained using monodisperse polystyrene.
[0016]
Examples 1-3
Using styrene, divinylbenzene (m-, p-mixture) as a compound having a plurality of vinyl groups, and 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) as a radical scavenger A solution prepared to have a composition as shown in Table 1 was polymerized at a polymerization temperature shown in Table 1. Table 1 shows the measurement results.
[0017]
Comparative Examples 1 to 7
Using styrene, divinylbenzene (m-, p-mixture) as a compound having a plurality of vinyl groups, and 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) as a radical scavenger The solutions prepared to have the compositions shown in Tables 2 and 3 were polymerized at the polymerization temperatures shown in Tables 2 and 3. Tables 2 and 3 show the measurement results.
[0018]
[Table 1]
[Table 2]
[0020]
[Table 3]
【The invention's effect】
The styrenic copolymer of the present invention is a copolymer of a styrenic compound and a compound having a plurality of vinyl groups, and has a narrow molecular weight distribution, and therefore does not contain an ultrahigh molecular weight component or a low molecular weight component, and is branched. The structure is not biased solely by the high molecular weight components.
According to the method of the present invention for producing a styrene-based copolymer by copolymerizing a styrene-based compound and a compound having a plurality of vinyl groups, gel formation in a production plant is suppressed, and production by a continuous bulk polymerization method is stabilized. It can be implemented in practice.
Claims (6)
ラジカル捕捉剤の存在下、スチレン系化合物および複数のビニル基を有する化合物を共重合させるに際し、
（１）重合される化合物に対する複数のビニル基を有する化合物濃度（Ｄ；ｍｏｌ％）およびラジカル捕捉剤濃度（Ｃ；ｍｏｌ％）が
（２）重合温度が１００〜１６０℃で、
（３）重合転化率が４０〜８０％となるまで重合を行う、
ことによって製造されたスチレン系共重合体。A copolymer of a styrene compound and a compound having a plurality of vinyl groups, having a weight average molecular weight (Mw) of 100,000 to 500,000, a number average molecular weight (Mn) of 50,000 to 400,000, and a molecular weight The distribution (Mw / Mn) is 1.5 or more and less than 2.5, and is the number of branches per 1000 units of styrene monomer in the number average molecular weight (Mn), weight average molecular weight (Mw), and z average molecular weight (Mz). Characterized in that the degree of branching (λ) is equal to or greater than 0.1 and less than 10 ,
When copolymerizing a styrene compound and a compound having a plurality of vinyl groups in the presence of a radical scavenger,
(1) The concentration of a compound having a plurality of vinyl groups with respect to the compound to be polymerized (D; mol%) and the concentration of a radical scavenger (C; mol%)
(2) When the polymerization temperature is 100 to 160 ° C,
(3) Polymerization until the polymerization conversion rate becomes 40 to 80%.
A styrene-based copolymer produced by the above method.
（１）重合される化合物に対する複数のビニル基を有する化合物濃度（Ｄ；ｍｏｌ％）およびラジカル捕捉剤濃度（Ｃ；ｍｏｌ％）が
（２）重合温度が１００〜１６０℃で、
（３）重合転化率が４０〜８０％となるまで重合を行う、
ことを特徴とするスチレン系共重合体の製造方法。In the presence of a radical scavenger, a method for producing a styrene-based polymer by copolymerizing a styrene-based compound and a compound having a plurality of vinyl groups,
(1) The concentration of a compound having a plurality of vinyl groups with respect to the compound to be polymerized (D; mol%) and the concentration of a radical scavenger (C; mol%)
(2) When the polymerization temperature is 100 to 160 ° C,
(3) Polymerization until the polymerization conversion rate becomes 40 to 80%.
A method for producing a styrene copolymer.
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| JP3414097A JP3595869B2 (en) | 1997-02-18 | 1997-02-18 | Styrene copolymer, method for producing the same, and molded article |
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| JP5314859B2 (en) * | 2007-07-27 | 2013-10-16 | 株式会社エフピコ | Laminate printing film, thermoforming sheet and packaging container |
| JP2009215354A (en) * | 2008-03-07 | 2009-09-24 | Dic Corp | Styrenic resin composition |
| JP2014189766A (en) * | 2013-03-28 | 2014-10-06 | Sekisui Plastics Co Ltd | Polystyrenic resin composition for foaming, polystyrenic resin foam sheet, and foam molding |
| EP2918388A1 (en) | 2014-03-10 | 2015-09-16 | Sulzer Chemtech AG | A process to recycle expandable plastic materials and an expandable or expanded plastic material obtainable thereby |
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