JP4576650B2 - Method for producing copolymer resin foam - Google Patents
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Description
【０００１】
【発明の属する技術分野】
本発明は、共重合樹脂発泡体の製造方法に関する。
【０００２】
【従来の技術】
一般に発泡材料の製造方法として、例えば、▲１▼分解型発泡剤と組成物を押出機で溶融混練し発泡させる方法、▲２▼樹脂を押出機で溶融させ、蒸発型発泡剤をシリンダー途中から直接圧注入し、混練、発泡させる方法、▲３▼樹脂ペレット、ビーズを押出機または水系懸濁液中で蒸発型発泡剤を含浸させ、その含浸ペレットまたはビーズを水蒸気等で加熱して発泡させる方法等が知られている。
また、超臨界状態にある二酸化炭素を熱可塑性樹脂中に含浸させる工程、常圧まで減圧する工程を有する発泡材料の製造方法が知られている(特表平６−５０６７２４号公報)。この方法で得られる発泡材料は、セル直径が0.1〜10μm、数密度が109〜1015cells/cm3の超微細発泡体であり、これまでの発泡材料製造方法では得られないという特徴を有する。また、この時に含浸させる二酸化炭素が超臨界状態や液体状態である方がさらに微細な発泡体となることが知られている(特開平１０−３６５４７号公報)。
また、一種類のモノマーからなる単独重合体は基本的に一物質につき一特性しか持たないが、二種類以上のモノマーを共重合させることで得られる共重合体は選ぶモノマーの組み合わせ、構造を工夫することで様々な特性を持つことも知られている。
【０００３】
【発明が解決しようとする課題】
超臨界状態あるいは液体状態にある高圧ガスを含浸させる発泡材料を製造する方法では、含浸させるガスが高圧であるほど微細な発泡体が得られることが知られている。しかしながら、より高圧の設備は多額のコストを要し、安全上も危険性が高いので、微細な発泡体を得るのに必要なガスの圧力を低くする工夫が工業化する上で必要である。
また、これまでに超臨界状態あるいは液体状態にある高圧ガスを含浸させる方法で得られる発泡材料を製造する上で、好適な共重合体の条件については何ら見出されていない。
本発明者は、特表平６−５０６７２４号公報、特開平１０−３６５４７号公報で示される樹脂中に高圧ガスを含浸させる工程、常圧まで減圧する工程を有する発泡材料の製造方法により、微細発泡体を製造する上で好適である共重合体の条件を見出し、本発明に至った。
【０００４】
【課題を解決するための手段】
即ち本発明は、２種類以上のモノマーの共重合体よりなるミクロ相分離構造を有する樹脂材料に、高圧ガスを接触させた後、発泡させることを特徴とする共重合樹脂発泡体の製造方法を提供するにある。
【０００５】
【発明実施の形態】
以下、本発明について詳細に説明する。
本発明は、樹脂中に高圧ガスを接触する方法により微細発泡体を製造する上で、２種以上のモノマーの共重合体のミクロ相分離構造を利用するものである。
【０００６】
本発明に於いて使用するミクロ相分離構造を有する樹脂材料を得るには、単独重合体であれば互いに非相溶なポリマーとなる２種以上のモノマーの組み合わせを選択する。共重合体中においては、ある部分の組成が１種類のモノマーの割合が他種のモノマーの割合より多くならなければミクロ相分離しない。
２種類以上のモノマーの共重合の形態として、交互共重合体、ランダム共重合体、ブロック共重合体、グラフト共重合体がある。本発明に好適なミクロ相分離構造を形成しうる共重合の形態はブロック共重合体、グラフト共重合体、およびブロック性の高いランダム共重合体である。
一般に２種のモノマーＭ1、Ｍ2からなる共重合体の交互性、ランダム性、ブロック性はモノマー反応性比r1，r2の積の大きさにより評価され、完全なランダム共重合系であるr1×r2＝１を基準として、r1×r2が１より小さいほど交互性が大きく、１よりも大きいほどブロック性が大きいことが知られている。イオン共重合に多く見られるr1×r2＞１となる組み合わせを選択すれば良好なミクロ相分離構造を持つ共重合体が得られやすい。ラジカル共重合ではr1×r2＜１となる組み合わせが多く、交互性が強いので、２種以上の単独重合体のポリマー鎖が末端部で結合したブロックコポリマーもしくは主鎖と異種の枝分かれ高分子鎖を持つグラフト共重合体になる様に工夫する必要がある。しかし、r1×r2＜１となる組み合わせにおいても一方の反応性比が１より大きい場合、例えばr1＞１である場合は、Ｍ1がＭ2に比べ優先的に消費されるので反応の後期にはＭ2の割合の多い並びが生じ、ミクロ相分離構造を持つ共重合体が得られやすい。
【０００７】
本発明で用いられる共重合体としては、ミクロ相分離構造を有していれば特に限定されることはなく、例えば、エチレン、スチレン、プロピレン、塩化ビニルの中から選ばれる２種以上のモノマーの共重合体の他、スチレンとイソプレン、ブタジエン、イソブテンとの共重合体、アクリロニトリル−ブタジエン−スチレン共重合体、エチレンとメチルメタクリレート、エチルアクリレート、ブチルメタクリレート、ブチルアクリレート、フッ化ビニルとの共重合体、プロピレンとメチルメタクリレート、エチルアクリレート、ブチルメタクリレート、ブチルアクリレートとの共重合体、メチルメタクリレートとブチルメタクリレート、ブチルアクリレート、スチレンとの共重合体、ジメチルシロキサン−イソブテン共重合体、ポリプロピレンオキシド−ポリブタジエン共重合体、ポリスルホン−ポリジメチルシロキサン共重合体などを用いることができる。
【０００８】
本発明において、共重合体を得る重合方法としては、懸濁重合法、乳化重合法、塊状重合法等が適用できる。r1×r2＜１となる組み合わせにおいても一方の反応性比が１より大きい場合、所望量のモノマーを反応槽に入れ重合率が１００％近くなるまで反応させることで、ブロック性の高い共重合体が比較的簡単に得られる。これは、共重合が進むにつれ残留モノマーの組成が変化し、重合初期に生成したポリマーと比べ、後期に生成したポリマーでは組成の偏りが大きいからである。この場合、特開平７−１２６３０８号公報に示すような連続的な塊状重合法のように重合率４５〜６０重量％で重合を終了する方法では、モノマー組成の偏りが十分でなくブロック性の高い共重合体は得にくい。
【０００９】
ミクロ相分離構造には「球構造」、「シリンダー構造」、「ラメラ構造」等があるが、本発明においては、分離界面が樹脂中に均一に分布しておればいずれの構造であってもよい。
【００１０】
該樹脂組成物の形態としては、溶融状、フィルム状、板状、所望の成型品形状など任意の形でよく、特に限定されない。
【００１１】
該樹脂組成物に接触させる高圧ガスとしては、従来公知のガスであればよく、例えば二酸化炭素、窒素、アルゴン、水素、酸素、ブタン、プロパン、空気等が挙げられる。こられは、単独、或いは２種類以上混合して用いても良い。中でも、該樹脂組成物に対して不活性であり、該樹脂組成物への溶解性が高く、かつ取扱いが容易である点より、約５０容量％以上の二酸化炭素を含有する高圧ガスの適用が好ましい。
【００１２】
該樹脂組成物に接触させる高圧ガスの圧力は、特に限定されるものではなく所望とする発泡体の物性により決定されるが、通常、０．２ＭＰａ以上であり、好ましくは１ＭＰａ以上である。圧力が低い場合は、発泡体のセル直径が大きくなり、他方圧力が高くなれば発泡体のセル直径が小さくなる傾向にある。上限は特に制限はなく、経済性等により主として決定されるが、通常４０ＭＰａ程度までである。
【００１３】
該樹脂組成物に接触させる高圧ガスの温度も、特に限定されるものではなく所望する発泡体の物性により決定されるが、通常約０〜３００℃であり、好ましくは０〜２００℃である。温度が高いと、該樹脂組成物が分解する恐れがあり好ましくない。温度が低いほど発泡体のセル直径が小さくなる傾向にあり、下限は特に制限はなく、経済性等により主として決定されるが、通常０℃までである。
【００１４】
該樹脂組成物に接触させる高圧ガスの状態は、特に制限されるものではないが、超臨界状態か液体状態であることが好ましい。高圧ガスが超臨界状態にあるとは、高圧ガスの温度、圧力が臨界点以上にあることを意味し、この状態では圧力を変えることで密度、粘度、拡散係数等を気体に近い状態から液体に近い状態まで幅広く変えることができる。周知の如く高圧ガスの臨界点は、高圧ガスの種類により異なる。例えば、二酸化炭素では、温度３０４．２Ｋ、圧力が７．４ＭＰａであり、窒素では温度１２６．２Ｋ、圧力３．４ＭＰａである。２種類以上のガスを混合した場合にも、混合ガスの種類、混合比に応じて臨界点が存在する。
【００１５】
該樹脂組成物に該高圧ガスを接触させる時間も特に限定されるものではなく処理対象となる該樹脂組成物の形状により決定されが、通常約０．１秒〜約７日、好ましくは、３０秒〜１２時間である。時間が上記範囲より短い場合は、該樹脂組成物の中心部まで該高圧ガスが拡散せず、常圧まで減圧した場合に、該樹脂組成物内部に発泡層が形成されない。処理時間の上限は、特に制限されるものではないが、該樹脂組成物中に該高圧ガスが拡散し飽和溶解量に達した後は、あまり長時間接触させても得られる発泡体の物性に影響せず、時間に見合う効果がなくなるので、通常操業効率より上記範囲内で処理される。
【００１６】
該樹脂組成物を該高圧ガスに接触させる方法は、該混合物が該高圧ガス雰囲気下で該高圧ガスと接触し得る状況下にあればよく、特にその手段は限定されるものではないが、例えば、フィルム状、板状、所望の成型品形状等の任意形状の該樹脂組成物を耐圧容器内に入れて容器全体にガスを注入する方法、溶融状態の該樹脂組成物を耐圧容器内や押出成形機内あるいは射出成形機内等に入れて該高圧ガスを注入する方法が挙げられる。
【００１７】
該高圧ガスと接触処理後の該樹脂組成物は、次いで常圧になるまで減圧し取り出せばよく、減圧する速度は特に制限されない。減圧速度があまり遅いと該樹脂組成物中に溶解した該高圧ガスが減圧中に溶出してきて発泡体が得られない場合がある。
【００１８】
得られた該高圧ガスと接触処理後の該樹脂組成物は、所望のセル直径にするために、さらに加熱処理しても良い。発泡させるために加熱する温度は、特に制限がないが、好ましくは３０〜２００℃である。発泡させるために加熱する温度が低すぎると加熱の効果が得られず、高すぎると得られる発泡体のセル直径が大きくなる傾向がある。加熱させる方法は、従来公知の方法でよい。例えば、オイルバス、ウォーターバスに浸漬させる方法、熱プレスを用いる方法が挙げられる。
【００１９】
該加熱処理後、所望のセル直径にするために冷却することが好ましい。冷却の方法として例えば、２０℃の水中に浸漬する方法があるが、その方法に特に制限されるものではない。
【００２０】
【発明の効果】
本発明で使用するミクロ相分離構造を有する共重合体は、従来の単独重合体や相分離構造を持たない共重合体と比較して、接触させるガスの圧力が比較的低くても容易に発泡させることができる。本発明によって得られる共重合樹脂発泡体は、発泡体のセル直径が小さく、かつ単位体積当たりのセル数も大きい発泡体が得られる。また、従来の共重合樹脂を用いた発泡体と同様に単独重合樹脂を用いた発泡体にない様々な特性を有するのみならず、発泡倍率が同じ場合の強度がつよく、照明、看板、ディスプレイ、建築材料に使用することができる。
【００２１】
【実施例】
以下、本発明を実施例に従って説明するが、本発明はこれに限定されるものではない。
なお、実施例中において行った物性測定、試験方法は以下に示す通りである。
（１）ＴＥＭ観察：発泡前のサンプルを処理し、ＴＥＭ観察を行った。メタクリル酸メチル／アクリル酸ブチル共重合体の場合は、ＲｕＯ４で７０℃、５時間染色、水洗、風乾後、切片を作成し、カーボンを蒸着した。
（２）セル直径、数密度：発泡体断面のＳＥＭ写真を画像処理ソフト（東洋紡績株式会社製、Image Analyzer V10LAB for Windows95）で統計処理した発泡体断面のセル直径の平均値をＤとした。また、次式よりセル数密度を求めた。
Ｎ= (ｎ/Ａ)3/2/(1-4/3π(Ｄ/2)3・(ｎ/Ａ)3/2)
（式中、Ｎはセル数密度、Ａは統計処理領域の面積、ｎはＡ中のセル個数、Ｄは平均セル直径を表す）
実施例で用いた各種単量体の略称は、以下の通り。
ＭＭＡ：メタクリル酸メチル
ＢＡ：アクリル酸ブチル
Ｓｔ：スチレン
【００２２】
実施例１
ＭＭＡ（Ｍ１）とＢＡ（Ｍ２）のラジカル重合反応性比はｒ1×ｒ2＜１であるがｒ1＞１である。２００ＬのＳＵＳ製オートクレーブに、ＭＭＡ７０重量部、ＢＡ３０重量部、ラウロイルパーオキサイドを０．４５重量部、ドデシルメルカプタン０．１重量部、イオン交換水を１２０重量部、１．２％ポリメタクリル酸ナトリウム水溶液３重量部とリン酸水素２ナトリウム・７水塩０．２５重量部、リン酸水素１ナトリウム０．２９重量部を入れて混合し、加熱昇温して、７５℃で重合開始し、１１０分経過後、さらに１００℃で３０分加熱することでほぼ完全に重合させた。重合後、洗浄、脱水、乾燥を行い、ビーズ状共重合体を得た。
得られたビーズ状共重合体の組成を熱分解ガスクロマトグラフで求めたところ平均組成比はＭＭＡ／ＢＡ＝７１／２９だった。
得られたビーズ状重合体を２００℃でプレスして厚さ０．５ｍｍのシートを得た。ＴＥＭ観察を行ったところ、ＢＡ成分の多い部分が、大きさ１００〜１５０ｎｍ程度の球状に分布しているミクロ相分離構造が観察された。写真１に観察結果を示す。
このシートを耐圧容器に入れ、１２〜３５ＭＰａ、４０℃の二酸化炭素で耐圧容器内を満たした。５時間後、１０秒で耐圧容器内を常圧まで減圧したのち発泡体を取り出した。
得られた発泡体の断面のＳＥＭ写真から画像処理によりセルサイズＤ、セル密度Ｎを求めた。結果を表１に示す。
【００２３】
比較例１
触媒溶解槽にＭＭＡをアゾビスイソブチロニトリルが０．２４重量％となるように仕込み、攪拌混合し、アゾビスイソブチロニトリルを完全に溶解させ触媒液とした。なお、触媒溶解槽内の温度は５℃になるようにジャケットに冷媒を通した。このように調合した触媒液をポンプにより、槽内温度が一定となる様調節しながら重合反応器へ供給した。
単量体調合槽にＭＭＡ、ＢＡ及びｎ−オクチルメルカプタンの濃度がそれぞれ６０重量部、４０重量部、０．２２重量部となるような新たなＭＭＡ、ＢＡ、回収未反応単量体及びｎ−オクチルメルカプタンを供給し調整し、温度を２０℃とした。このようにして調整した単量体混合液をポンプにより供給した。
重合反応器に上記触媒溶液及び単量体混合液を供給し、平均滞留時間８０分、槽内温度１７５±２℃、槽内圧１６ｋｇ／ｃｍ2で重合を継続した。得られる液状の重合体組成物を重合反応器最上部から取り出した。
次いで、重合体組成物を脱気し、未反応単量体を取り除いた。重合体は溶融状態でストランド状に押し出し、水冷後細断してペレットを得た。この時の重合率は約４５％であった。
得られたペレット状共重合体の組成をガスクロマトグラフィーで求めたところ平均組成比はＭＭＡ／ＢＡ＝７１／２９だった。
ペレットを１４５℃でプレスして厚さ０．５ｍｍのシートを得た。ＴＥＭ観察を行ったところ、ＢＡ成分は一様に分布しておりミクロ相分離構造は観察されなかった。写真２に観察結果を示す。
このシートを用いて、実施例１と同様の操作で発泡体を得た。得られた発泡体の断面のＳＥＭ写真から画像処理によりセルサイズＤ、セル密度Ｎを求めた。結果を表１に示す。
【００２４】
比較例２
ＭＭＡ（Ｍ１）とＳｔ（Ｍ２）のラジカル重合反応性比はｒ1＜１、ｒ2＜１である。２００ＬのＳＵＳ製オートクレーブに、ＭＭＡ７７重量部、Ｓｔ２３重量部、２，２アゾビス（２−４ジメチルバレロニトリル）を０．１重量部、２，４，４−トリメチルペンチル−２−パーオキシ２−エチルヘキサノエート０．５重量部、シクロヘキサン１メチル４（１）エチリデン０．０３重量部、イオン交換水を１２０重量部、１．２％ポリメタクリル酸ナトリウム水溶液３重量部とリン酸水素２ナトリウム・７水塩０．２５重量部、リン酸水素１ナトリウム０．２９重量部を入れて混合し、加熱昇温して、８３℃で重合開始し、８０分経過後、さらに１０５℃で３０分加熱することでほぼ完全に重合させた。重合後、洗浄、脱水、乾燥を行い、ビーズ状共重合体を得た。
得られたビーズ状共重合体の組成を熱分解ガスクロマトグラフで求めたところ平均組成比はＭＭＡ／Ｓｔ＝７４．５／２５．５だった。
得られたビーズ状重合体を２２０℃でプレスして厚さ０．９ｍｍのシートを得た。シートは透明で、相分離していなかった。このシートを耐圧容器に入れ、１２〜３５ＭＰａ、４０℃の二酸化炭素で耐圧容器内を満たした。５時間後、１０秒で耐圧容器内を常圧まで減圧したのち発泡体を取り出した。
得られた発泡体の断面のＳＥＭ写真から画像処理によりセルサイズＤ、セル密度Ｎを求めた。結果を表１に示す。
【００２５】
【表１】
【図面の簡単な説明】
【図１】 実施例1の方法により得られた発泡処理前のシートのＴＥＭ写真を示す。
【図２】 比較例１の方法により得られた発泡処理前のシートのＴＥＭ写真を示す。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a copolymer resin foam.
[0002]
[Prior art]
In general, as a method for producing a foam material, for example, (1) a method in which a decomposable foaming agent and a composition are melted and kneaded with an extruder and foamed, and (2) a resin is melted in an extruder and an evaporative foaming agent is introduced from the middle of the cylinder. (3) Resin pellets and beads are impregnated with an evaporating foaming agent in an extruder or aqueous suspension, and the impregnated pellets or beads are heated with steam or the like to be foamed. Methods are known.
Also known is a method for producing a foam material having a step of impregnating a thermoplastic resin with carbon dioxide in a supercritical state and a step of reducing the pressure to normal pressure (Japanese Patent Publication No. 6-506724). The foamed material obtained by this method is an ultrafine foam having a cell diameter of 0.1 to 10 μm and a number density of 10 9 to 10 15 cells / cm 3 , and is characterized by the fact that it cannot be obtained by conventional foaming material manufacturing methods. Have. Further, it is known that a finer foam is obtained when the carbon dioxide impregnated at this time is in a supercritical state or a liquid state (Japanese Patent Laid-Open No. 10-36547).
In addition, a homopolymer consisting of one type of monomer basically has only one characteristic per substance, but a copolymer obtained by copolymerizing two or more types of monomers is a combination of the selected monomers and a devising structure. It is also known to have various characteristics.
[0003]
[Problems to be solved by the invention]
In a method for producing a foam material impregnated with a high-pressure gas in a supercritical state or a liquid state, it is known that a finer foam can be obtained as the pressure of the impregnated gas is higher. However, higher-pressure equipment requires a large amount of cost and is highly dangerous for safety. Therefore, a device for lowering the gas pressure necessary to obtain a fine foam is necessary for industrialization.
In addition, no suitable copolymer conditions have been found so far for producing a foam material obtained by a method of impregnating a high-pressure gas in a supercritical state or a liquid state.
The present inventor has developed a method for producing a foam material having a step of impregnating a high-pressure gas into a resin and a step of reducing the pressure to normal pressure shown in JP-A-6-506724 and JP-A-10-36547. The present inventors have found the conditions for a copolymer that is suitable for producing a foam, and have reached the present invention.
[0004]
[Means for Solving the Problems]
That is, the present invention provides a method for producing a copolymer resin foam, comprising: bringing a high-pressure gas into contact with a resin material having a microphase-separated structure composed of a copolymer of two or more types of monomers, followed by foaming. In offer.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
The present invention utilizes a microphase-separated structure of a copolymer of two or more monomers when producing a fine foam by a method of contacting a high-pressure gas in a resin.
[0006]
In order to obtain a resin material having a microphase-separated structure used in the present invention, a combination of two or more monomers that are incompatible polymers with each other is selected if it is a homopolymer. In the copolymer, microphase separation does not occur unless the proportion of one type of monomer is greater than the proportion of other types of monomers.
As a form of copolymerization of two or more kinds of monomers, there are an alternating copolymer, a random copolymer, a block copolymer, and a graft copolymer. The form of copolymer that can form a microphase-separated structure suitable for the present invention is a block copolymer, a graft copolymer, and a random copolymer having a high block property.
In general, the alternation, randomness and blockiness of a copolymer consisting of two types of monomers M 1 and M 2 are evaluated by the product size of the monomer reactivity ratios r 1 and r 2. On the basis of a certain r 1 × r 2 = 1, it is known that as r 1 × r 2 is smaller than 1, the alternation is larger and as r 1 is larger than 1, the block property is larger. If a combination of r 1 × r 2 > 1 often found in ionic copolymerization is selected, a copolymer having a good microphase separation structure can be easily obtained. In radical copolymerization, there are many combinations where r 1 × r 2 <1, and the alternation is strong. Therefore, a block copolymer in which polymer chains of two or more homopolymers are bonded at the terminal portion or a branched polymer different from the main chain. It is necessary to devise a graft copolymer having a chain. However, even in the combination of r 1 × r 2 <1, if one reactivity ratio is greater than 1, for example, r 1 > 1, M 1 is consumed preferentially compared to M 2 , so that In the latter stage, an arrangement with a large proportion of M 2 occurs, and it is easy to obtain a copolymer having a microphase separation structure.
[0007]
The copolymer used in the present invention is not particularly limited as long as it has a microphase-separated structure. For example, two or more monomers selected from ethylene, styrene, propylene, and vinyl chloride are used. Copolymers, copolymers of styrene and isoprene, butadiene, isobutene, acrylonitrile-butadiene-styrene copolymers, copolymers of ethylene and methyl methacrylate, ethyl acrylate, butyl methacrylate, butyl acrylate, vinyl fluoride , Copolymer of propylene and methyl methacrylate, ethyl acrylate, butyl methacrylate, butyl acrylate, copolymer of methyl methacrylate and butyl methacrylate, butyl acrylate, styrene, dimethylsiloxane-isobutene copolymer, polypropylene Kishido - polybutadiene copolymer, polysulfone - poly dimethylsiloxane copolymer, etc. may be used.
[0008]
In the present invention, a suspension polymerization method, an emulsion polymerization method, a bulk polymerization method, or the like can be applied as a polymerization method for obtaining a copolymer. Even in the combination of r 1 × r 2 <1, if one reactivity ratio is larger than 1, a desired amount of monomer is placed in a reaction vessel and reacted until the polymerization rate is close to 100%. A polymer is obtained relatively easily. This is because as the copolymerization proceeds, the composition of the residual monomer changes, and the polymer produced in the later stage has a greater compositional bias than the polymer produced in the early stage of polymerization. In this case, in the method of terminating the polymerization at a polymerization rate of 45 to 60% by weight as in the continuous bulk polymerization method as shown in JP-A-7-126308, the monomer composition is not sufficiently biased and the block property is high. Copolymers are difficult to obtain.
[0009]
Microphase separation structures include “spherical structure”, “cylinder structure”, “lamella structure”, etc. In the present invention, any structure can be used as long as the separation interface is uniformly distributed in the resin. Good.
[0010]
The form of the resin composition is not particularly limited, and may be any form such as a molten form, a film form, a plate form, or a desired molded product form.
[0011]
The high-pressure gas brought into contact with the resin composition may be any conventionally known gas, and examples thereof include carbon dioxide, nitrogen, argon, hydrogen, oxygen, butane, propane, and air. These may be used alone or in admixture of two or more. Among them, the application of a high-pressure gas containing about 50% by volume or more of carbon dioxide is preferable because it is inert to the resin composition, has high solubility in the resin composition, and is easy to handle. preferable.
[0012]
The pressure of the high-pressure gas brought into contact with the resin composition is not particularly limited and is determined by the desired physical properties of the foam, but is usually 0.2 MPa or more, preferably 1 MPa or more. When the pressure is low, the cell diameter of the foam increases, and when the pressure increases, the cell diameter of the foam tends to decrease. The upper limit is not particularly limited and is mainly determined by economics and the like, but is usually up to about 40 MPa.
[0013]
The temperature of the high-pressure gas brought into contact with the resin composition is not particularly limited, and is determined by the desired physical properties of the foam, but is usually about 0 to 300 ° C, preferably 0 to 200 ° C. A high temperature is not preferable because the resin composition may be decomposed. The cell diameter of the foam tends to be smaller as the temperature is lower, and the lower limit is not particularly limited and is mainly determined by economics and the like, but is usually up to 0 ° C.
[0014]
The state of the high-pressure gas brought into contact with the resin composition is not particularly limited, but is preferably a supercritical state or a liquid state. The high-pressure gas being in a supercritical state means that the temperature and pressure of the high-pressure gas are above the critical point. In this state, the density, viscosity, diffusion coefficient, etc. can be changed from a state close to gas by changing the pressure. It can be widely changed to a state close to. As is well known, the critical point of high-pressure gas varies depending on the type of high-pressure gas. For example, carbon dioxide has a temperature of 304.2 K and a pressure of 7.4 MPa, and nitrogen has a temperature of 126.2 K and a pressure of 3.4 MPa. Even when two or more kinds of gases are mixed, there is a critical point depending on the kind and mixing ratio of the mixed gas.
[0015]
The time for which the high-pressure gas is brought into contact with the resin composition is not particularly limited, and is determined by the shape of the resin composition to be treated, and is usually about 0.1 seconds to about 7 days, preferably 30. Second to 12 hours. When the time is shorter than the above range, the high-pressure gas does not diffuse to the center of the resin composition, and no foam layer is formed inside the resin composition when the pressure is reduced to normal pressure. The upper limit of the treatment time is not particularly limited, but after the high-pressure gas diffuses into the resin composition and reaches the saturated dissolution amount, the physical properties of the foam obtained even if the contact is made for a long time. Since there is no effect and the effect corresponding to the time is lost, it is processed within the above range from the normal operation efficiency.
[0016]
The method of bringing the resin composition into contact with the high-pressure gas is not particularly limited as long as the mixture can be in contact with the high-pressure gas under the high-pressure gas atmosphere. , A method of injecting a gas into the entire pressure vessel by placing the resin composition in an arbitrary shape such as a film shape, a plate shape, or a desired molded product shape into the pressure vessel, or extruding the resin composition in a molten state in the pressure vessel Examples thereof include a method of injecting the high-pressure gas into a molding machine or an injection molding machine.
[0017]
The resin composition after contact treatment with the high-pressure gas may then be decompressed and taken out until it reaches normal pressure, and the speed of depressurization is not particularly limited. If the pressure reduction rate is too slow, the high-pressure gas dissolved in the resin composition may elute during pressure reduction and a foam may not be obtained.
[0018]
The obtained resin composition after contact treatment with the high-pressure gas may be further subjected to heat treatment in order to obtain a desired cell diameter. The temperature for heating to foam is not particularly limited, but is preferably 30 to 200 ° C. If the heating temperature for foaming is too low, the effect of heating cannot be obtained, and if it is too high, the cell diameter of the resulting foam tends to increase. The heating method may be a conventionally known method. For example, the method of immersing in an oil bath and a water bath, and the method of using a heat press are mentioned.
[0019]
After the heat treatment, cooling is preferably performed to obtain a desired cell diameter. As a cooling method, for example, there is a method of immersing in 20 ° C. water, but the method is not particularly limited.
[0020]
【The invention's effect】
The copolymer having a microphase separation structure used in the present invention is easily foamed even when the pressure of the gas to be contacted is relatively low compared to conventional homopolymers and copolymers having no phase separation structure. Can be made. The copolymer resin foam obtained by the present invention provides a foam having a small cell diameter of the foam and a large number of cells per unit volume. In addition, it has various characteristics not found in a foam using a homopolymer resin as well as a foam using a conventional copolymer resin, and the strength when the expansion ratio is the same is strong. Can be used for building materials.
[0021]
【Example】
Hereinafter, although the present invention is explained according to an example, the present invention is not limited to this.
In addition, the physical-property measurement performed in the Example and the test method are as showing below.
(1) TEM observation: The sample before foaming was processed and TEM observation was performed. In the case of a methyl methacrylate / butyl acrylate copolymer, sections were prepared after staining with
(2) Cell diameter and number density: D is the average cell diameter of the foam cross-section obtained by statistically processing the SEM photograph of the foam cross-section with image processing software (Image Analyzer V10LAB for Windows95, manufactured by Toyobo Co., Ltd.). Moreover, the cell number density was calculated | required from following Formula.
N = (n / A) 3/2 / (1-4 / 3π (D / 2) 3 · (n / A) 3/2 )
(Where N is the cell density, A is the area of the statistical processing region, n is the number of cells in A, and D is the average cell diameter)
Abbreviations of various monomers used in the examples are as follows.
MMA: Methyl methacrylate BA: Butyl acrylate St: Styrene
Example 1
The radical polymerization reactivity ratio between MMA (M1) and BA (M2) is r 1 × r 2 <1, but r 1 > 1. In a 200 L SUS autoclave, 70 parts by weight of MMA, 30 parts by weight of BA, 0.45 parts by weight of lauroyl peroxide, 0.1 part by weight of dodecyl mercaptan, 120 parts by weight of ion-exchanged water, 1.2% sodium polymethacrylate aqueous solution 3 parts by weight, 0.25 parts by weight of disodium hydrogen phosphate / 7 water salt and 0.29 parts by weight of sodium hydrogen phosphate were mixed, heated, heated, and polymerization started at 75 ° C. for 110 minutes. After the lapse of time, it was further polymerized almost completely by heating at 100 ° C. for 30 minutes. After polymerization, washing, dehydration, and drying were performed to obtain a bead copolymer.
When the composition of the obtained bead copolymer was obtained by pyrolysis gas chromatography, the average composition ratio was MMA / BA = 71/29.
The obtained bead polymer was pressed at 200 ° C. to obtain a sheet having a thickness of 0.5 mm. As a result of TEM observation, a microphase-separated structure in which a portion having a large BA component was distributed in a spherical shape having a size of about 100 to 150 nm was observed. Photo 1 shows the observation results.
This sheet was put into a pressure vessel, and the inside of the pressure vessel was filled with carbon dioxide at 12 to 35 MPa and 40 ° C. After 5 hours, the pressure inside the pressure vessel was reduced to normal pressure in 10 seconds, and then the foam was taken out.
Cell size D and cell density N were determined from the SEM photograph of the cross section of the obtained foam by image processing. The results are shown in Table 1.
[0023]
Comparative Example 1
MMA was charged into the catalyst dissolution tank so that azobisisobutyronitrile was 0.24% by weight, and stirred and mixed to completely dissolve azobisisobutyronitrile to obtain a catalyst solution. Note that the refrigerant was passed through the jacket so that the temperature in the catalyst dissolution tank was 5 ° C. The catalyst solution thus prepared was supplied to the polymerization reactor by a pump while adjusting the temperature in the tank to be constant.
New MMA, BA, recovered unreacted monomer and n- such that the concentrations of MMA, BA and n-octyl mercaptan are 60 parts by weight, 40 parts by weight and 0.22 parts by weight in the monomer preparation tank, respectively. Octyl mercaptan was supplied and adjusted to a temperature of 20 ° C. The monomer mixture prepared as described above was supplied by a pump.
The catalyst solution and the monomer mixture were supplied to the polymerization reactor, and polymerization was continued at an average residence time of 80 minutes, a tank temperature of 175 ± 2 ° C., and a tank pressure of 16 kg / cm 2 . The resulting liquid polymer composition was removed from the top of the polymerization reactor.
Subsequently, the polymer composition was deaerated to remove unreacted monomers. The polymer was extruded in the form of a strand in the molten state, and after cooling with water, it was chopped to obtain pellets. The polymerization rate at this time was about 45%.
When the composition of the obtained pellet-shaped copolymer was determined by gas chromatography, the average composition ratio was MMA / BA = 71/29.
The pellet was pressed at 145 ° C. to obtain a sheet having a thickness of 0.5 mm. When TEM observation was performed, the BA component was uniformly distributed, and the microphase separation structure was not observed.
Using this sheet, a foam was obtained in the same manner as in Example 1. Cell size D and cell density N were determined from the SEM photograph of the cross section of the obtained foam by image processing. The results are shown in Table 1.
[0024]
Comparative Example 2
The radical polymerization reactivity ratio between MMA (M1) and St (M2) is r 1 <1 and r 2 <1. In a 200 L SUS autoclave, 77 parts by weight of MMA, 23 parts by weight of St, 0.1 part by weight of 2,2azobis (2-4dimethylvaleronitrile), 2,4,4-trimethylpentyl-2-peroxy-2-ethylhexa 0.5 parts by weight of noate, 0.03 parts by weight of cyclohexane 1-methyl 4 (1) ethylidene, 120 parts by weight of ion-exchanged water, 3 parts by weight of 1.2% sodium polymethacrylate aqueous solution and disodium hydrogen phosphate · 7 Add 0.25 parts by weight of water salt and 0.29 parts by weight of monosodium hydrogen phosphate, mix, heat to increase temperature, start polymerization at 83 ° C, and after 80 minutes, heat at 105 ° C for 30 minutes. Almost completely polymerized. After polymerization, washing, dehydration, and drying were performed to obtain a bead copolymer.
The composition of the obtained bead copolymer was determined by pyrolysis gas chromatography, and the average composition ratio was MMA / St = 74.5 / 25.5.
The obtained bead polymer was pressed at 220 ° C. to obtain a sheet having a thickness of 0.9 mm. The sheet was transparent and not phase separated. This sheet was put into a pressure vessel, and the inside of the pressure vessel was filled with carbon dioxide at 12 to 35 MPa and 40 ° C. After 5 hours, the inside of the pressure vessel was reduced to normal pressure in 10 seconds, and then the foam was taken out.
Cell size D and cell density N were determined from the SEM photograph of the cross section of the obtained foam by image processing. The results are shown in Table 1.
[0025]
[Table 1]
[Brief description of the drawings]
1 shows a TEM photograph of a sheet before foaming treatment obtained by the method of Example 1. FIG.
2 shows a TEM photograph of a sheet before foaming treatment obtained by the method of Comparative Example 1. FIG.
Claims (6)
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| JP33987099A JP4576650B2 (en) | 1999-11-30 | 1999-11-30 | Method for producing copolymer resin foam |
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| JP33987099A JP4576650B2 (en) | 1999-11-30 | 1999-11-30 | Method for producing copolymer resin foam |
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| JP4576650B2 true JP4576650B2 (en) | 2010-11-10 |
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| JP2003049018A (en) * | 2001-08-08 | 2003-02-21 | Idemitsu Petrochem Co Ltd | Foam, method for producing the same and reflection plate |
| JP2008303236A (en) * | 2007-06-05 | 2008-12-18 | Mitsubishi Plastics Inc | Manufacturing method for cellular material, and cellular material |
| RU2012143158A (en) * | 2010-03-10 | 2014-04-20 | ДАУ ГЛОБАЛ ТЕКНОЛОДЖИЗ ЭлЭлСи | NANOPOROUS FOAM POLYMER, CHARACTERIZED BY HIGH CELL ACHYLITY IN THE ABSENCE OF NANO-FILLER |
| JP2012140630A (en) * | 2012-03-08 | 2012-07-26 | Mitsubishi Plastics Inc | Method for manufacturing foam, and foam |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH04505775A (en) * | 1989-12-14 | 1992-10-08 | フアルミタリア・カルロ・エルバ・エツセ・エルレ・エルレ | Use of supercritical fluids to obtain porous sponges of biodegradable polymers |
| WO1996016111A1 (en) * | 1994-11-18 | 1996-05-30 | Dow Kakoh Kabushiki Kaisha | Polystyrene resin foam and process for producing the foam |
| JPH09500151A (en) * | 1993-05-05 | 1997-01-07 | ベーリンガー、インゲルハイム、カーゲー | Method for shaping thermoplastic materials, especially absorbent thermoplastic materials |
| JPH10130419A (en) * | 1996-05-22 | 1998-05-19 | E I Du Pont De Nemours & Co | Foamed fluoropolymer |
| JP2000169615A (en) * | 1998-12-02 | 2000-06-20 | Nitto Denko Corp | Production of fine porous foam |
| JP2001013971A (en) * | 1999-06-30 | 2001-01-19 | Nitto Denko Corp | Microporous soundproof material |
-
1999
- 1999-11-30 JP JP33987099A patent/JP4576650B2/en not_active Expired - Fee Related
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH04505775A (en) * | 1989-12-14 | 1992-10-08 | フアルミタリア・カルロ・エルバ・エツセ・エルレ・エルレ | Use of supercritical fluids to obtain porous sponges of biodegradable polymers |
| JPH09500151A (en) * | 1993-05-05 | 1997-01-07 | ベーリンガー、インゲルハイム、カーゲー | Method for shaping thermoplastic materials, especially absorbent thermoplastic materials |
| WO1996016111A1 (en) * | 1994-11-18 | 1996-05-30 | Dow Kakoh Kabushiki Kaisha | Polystyrene resin foam and process for producing the foam |
| JPH10130419A (en) * | 1996-05-22 | 1998-05-19 | E I Du Pont De Nemours & Co | Foamed fluoropolymer |
| JP2000169615A (en) * | 1998-12-02 | 2000-06-20 | Nitto Denko Corp | Production of fine porous foam |
| JP2001013971A (en) * | 1999-06-30 | 2001-01-19 | Nitto Denko Corp | Microporous soundproof material |
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