JP4027020B2 - Conductive graft polymer containing phosphoric acid group, method for producing the same, and coating agent - Google Patents

Description

［ただし一般式(I)において、R₁はH又はCH₃を表し、R₂はH、CH₃またはCH₂X（Xはハロゲン）を表す。nは１〜６の整数を表す。リン酸基は解離していてもよいし、錯塩を形成していても良い。］により表されるリン酸基含有不飽和単量体と、 (B) 下記式 (II) ：
【化８】

（ただし式 (II) において、 l と m は重合比を表し、 10 ≦ l ≦ 50 、 50 ≦ m ≦ 90 であって、 l と m との和は 100 である。）により表されるＮ - メトキシメチル化ナイロン - ６とからなる混合物、又は(2) 前記リン酸基含有不飽和単量体と、前記Ｎ - メトキシメチル化ナイロン - ６と、メタクリル酸とからなる混合物をラジカル重合することにより、優れた溶媒溶解性を有するとともに、帯電防止効果が湿度によらず安定しており、耐水性及び耐アルコール性に優れた被膜を与える導電性グラフト重合体が得られることを見出し、本発明に想到した。
【００１０】
本発明の導電性グラフト重合体は、Ｎ - メトキシメチル化ナイロン - ６及びリン酸基を有する不飽和単量体を必須成分として、溶液状態でラジカル重合開始剤の存在下で加熱重合せしめて、不飽和単量体の少なくとも一部をＮ - メトキシメチル化ナイロン - ６にグラフト重合させたものである。すなわち、本発明は、一般式(I)のリン酸基含有不飽和単量体と式 (II) のＮ - メトキシメチル化ナイロン - ６との混合物をラジカル重合して得られる反応物を有効成分とするものであり、導電性グラフト重合体中において、一般式(I)の少なくとも一部はＮ - メトキシメチル化ナイロン - ６にグラフト重合して、グラフト化したＮ - メトキシメチル化ナイロン - ６として存在すると推定される。
【００１１】
本発明の導電性グラフト重合体から得られるコーティング膜は耐水性及び耐アルコール性に優れているが、これはリン酸基間の会合によるものと考えられる。すなわち、ポリアミド樹脂にリン酸基含有不飽和単量体をグラフト重合すると、共有結合的架橋がなくとも、リン酸基間の会合により見かけの架橋が生成する故に、架橋触媒、架橋剤を添加しなくとも、水不溶性（膨潤性）のゲルになるという研究事実（例えば中前ら；第35回高分子年次大会（1989））から、耐水性の改良に寄与すると考えられる。
【００１２】
【発明の実施の形態】
[1] 導電性グラフト重合体
(A) ポリアミド樹脂
本発明に用いるポリアミド樹脂は、溶剤に対する溶解性を有し、且つリン酸基含有不飽和単量体によりグラフト重合されうるものであれば、特に限定されない。本発明に用いるポリアミド樹脂は、分子量1,000〜1,000,000が好ましく、より好ましくは2,000〜500,000であり、さらに好ましくは5,000〜150,000である。またポリアミド樹脂は、分子内にグラフトが可能な部位を 50以上有することが好ましく、100以上有することがより好ましい。
【００１３】
本発明に好ましく用いることのできるポリアミド樹脂としては、下記一般式(V)により表されるポリアミド樹脂が挙げられる。
【化９】

【００１４】
一般式(V)において、Ｒ₃びＲ₄はそれぞれ独立に炭素数３〜20の置換又は無置換のアルキレン基を表す。置換基としては、炭素数１〜６のアルキル基、ハロゲン等が挙げられる。好ましいＲ₃及びＲ₄は、炭素数５〜11の無置換のアルキレン基、より好ましくはn-ペンチレンである。
【００１５】
Ｒ₅は、炭素数１〜６の置換又は無置換のアルキレン基を表す。置換基としては、Ｒ₃及びＲ₄と同様のものでよい。好ましいＲ₅は、メチレンである。
【００１６】
Ｒ₆はそれぞれ独立に炭素数１〜６の置換又は無置換のアルキル基を表す。置換基としては、Ｒ₃及びＲ₄と同様のものでよい。好ましいＲ₆は、メチルである。
【００１７】
ｌとｍは重合比を表し、ｌとｍとの和は100である。10≦ｌ≦50、50≦ｍ≦90であることが好ましく、20≦ｌ≦30、70≦ｍ≦80であることがより好ましい。ｌが10未満だと、溶媒溶解性が低下するので好ましくない。またｌ＞50を狙っても、置換基の立体障害のため50超にすることは困難である。
【００１８】
ポリアミド樹脂としては、下記式 (II) ：
【化１０】

（ただし式 (II) において、 l と m は重合比を表し、 10 ≦ l ≦ 50 、 50 ≦ m ≦ 90 であって、 l と m との和は 100 である。）により表されるＮ - メトキシメチル化ナイロン - ６がより好ましい。一般式(II)のポリアミド樹脂の具体例として、帝国化学産業株式会社から製販されているトレジンF30K、トレジンMF-30、トレジンEF-30T等が挙げられる。
【００１９】
(Ｂ)リン酸基含有不飽和単量体
本発明で使用されるリン酸基含有不飽和単量体は、下記一般式(I)により表される。
【化６】

【００２０】
一般式(I)において、Ｒ₁は、Ｈ又はＣＨ₃を表し、Ｒ₂は、Ｈ、ＣＨ₃またはＣＨ₂Ｘ(Ｘはハロゲン)を表す。
【００２１】
リン酸基は解離していてもよいし、錯塩を形成していても良い。この場合、電荷を中和させるため、例えば、第１級、第２級、第３級及び第４級のアルキル基、アリル基、アラルキル基を含有するアンモニウムイオンやモノ、ジ、トリアルカノールアミン残基と錯塩を形成することが好ましく、特にＮ⁺Ｒ⁷ _4-p（ＯＨ）_p（ここで、は炭素数１〜18のアルキル基、炭素数６〜12の芳香族基、炭素数６〜12の脂環族基の中から選ばれた基を表し、ｐは１〜３の正の整数を表す。）が好ましい。
【００２２】
ｎは１〜６の整数を表し、好ましくは４〜６である。
【００２３】
一般式(I)の具体例としては、ユニケミカル株式会社から製販されているPhosmer^TM類が挙げられる。
【００２４】
【化７】

【００２５】
このうち、特に好ましいものはPhosmer PP、Phosmer PEである。
【００２６】
なお、一般式(I)のリン酸基含有不飽和単量体とともに、これと共重合しうる他の不飽和単量体を併用してもよい。他の不飽和単量体を併用する場合、 [リン酸基含有不飽和単量体]／[他の不飽和単量体] を重量比で0.1以上とし、好ましくは0.5以上、より好ましくは１以上とする。
【００２７】
他の不飽和単量体としては、分子内にカルボン酸基、酸無水物基、水酸基、エポキシ基、エーテル基、エステル基、アミド基、ニトリル基及びスルホン酸基等の親水性基を含む不飽和単量体の群（A）と、これらの親水性基を含まない群（B）とがある。群（A）の具体例としては、(メタ)アクリル酸、無水マレイン酸、ヒドロキシ(メタ)アクリレート、ポリエチレングリコール(メタ)アクリレート、ポリプロピレングリコール(メタ)アクリレート、メチル(メタ)アクリレート、酢酸ビニル、ジメチル(メタ)アクリルアミド、ジエチル(メタ)アクリルアミド、(メタ)アクリロニトリル等が挙げられる。群(B) の具体例としては、エチレン性のモノ不飽和炭化水素、塩化ビニル、各種スチレン類、ブタジエンなどの共役ジオレフィンが挙げられる。群(A)に属する単量体と群(B)に属する単量体の使用割合(A)／(B)を重量比で１以上とすることが好ましい。
【００２８】
(Ｃ)グラフト重合
グラフト重合は公知の方法に従って行えばよい。例えば、ナイロン-６等のポリアミド樹脂を溶解した反応系において、各種不飽和単量体をラジカル重合開始剤を用いて重合し、グラフト重合体を得る方法が知られている（例えば、小佐井ら、日本化学会誌；1975（3） 523−526）。
【００２９】
骨格となるポリアミド樹脂に対してグラフト重合させる不飽和単量体（リン酸基含有不飽和単量体と他の不飽和単量体の総和）の比率[(不飽和単量体)／(ポリアミド樹脂)]は、固形分重量ベースで0.05〜５の範囲が好ましく、0.1〜１がより好ましい。当該比率が５を超えると、グラフト重合が有効に行われずに単量体のみの重合物が比較的多く生成する結果になる。一方、0.05未満だと、グラフト重合による変性の程度が小さくなり、目的を達成することができない。
【００３０】
不飽和単量体は重合初期に一括添加しても良いし、重合経過に添って分割添加しても良い。分割添加する場合はリン酸基含有不飽和単量体と他の不飽和単量体とを混合して分割添加する方がグラフト重合体の組成を均質化する点から好ましい。
【００３１】
グラフト重合を行う系は均一溶液系であることが好ましい。そのために、少なくともポリアミド樹脂を溶解する溶剤を選びグラフト重合に供する前にあらかじめその溶剤に溶解しておくことが必要である。例えば、ポリアミド樹脂としてＮ-メトキシメチル化ナイロン-６（トレジンF30K、帝国化学産業(株)製）を用いる場合、溶媒として、メタノール、エタノール、イソプロパノール、エチレングリコール、ポリエチレングリコール、グリセリン、エチルセルソルブ、ブチルセルソルブ等のアルコール系の溶剤が好適に用いられる。溶剤中のポリアミド樹脂の濃度は５〜50wt％の範囲が好ましい。特に10〜25wt％の範囲が溶液粘度からして好適である。
【００３２】
ラジカル重合開始剤としては、2,2-アゾビスイソブチロニトリル、2,2-アゾビス（2,4-ジメチルバレロニトリル）、ジメチル2,2-アゾビス（2-メチルプロピオネート）、ジメチル2,2-アゾビスイソブチレートなどのアゾ系開始剤や、ベンゾイルパーオキシド、ラウロイルパーオキシド、ターシャリーブチルパーオキシ・ピバレートなどの過酸化物系の開始剤が、所望する重合反応温度に応じて選択して使用される。使用量はグラフト重合させる不飽和単量体の総和に対して0.1〜5wt％の範囲である。これを重合初期に一括添加しても良いし、また一部を反応過程で分割添加しても良い。
【００３３】
グラフト重合は通常の方法により行う。一例を挙げれば、攪拌器付き、還流冷却器付き反応器に予め溶解したポリアミド樹脂の溶液、反応溶媒、グラフト重合させる不飽和単量体混合液のうちの初期添加分、および重合開始剤のうちの初期添加分を加えて、40℃〜90℃、好ましくは50℃〜80℃に昇温して行う。不飽和単量体混合物の残部および重合開始剤の残部は反応過程で所定時間経過後に一括または分割して添加する。反応温度は最初から最後まで一定である必要はなく、重合末期に温度を上げて未反応単量体を極力少なくする方法を取ることが多い。
【００３４】
[2] コーティング剤
本発明のコーティング剤は、本発明の導電性グラフト重合体を用いたものである。導電性グラフト重合体は粗製のままでも良いし、精製しても良い。精製する場合、反応生成物を一旦、貧溶媒中に投入し、グラフト重合物を析出させ、次いで析出物を再度良溶媒に溶解する操作を繰り返せばよい。貧溶媒としては水が好ましいが、水中に析出しない場合はアセトン等を用いて反応生成物を析出させる。貧溶媒は反応生成物の有姿の３倍〜10倍と大過剰量使用する。ポリアミド樹脂にグラフト重合していない不飽和単量体のみの重合物が生成していれば、（アルコール＋水）溶媒、（アルコール＋アセトン）溶媒に可溶なので液層側に溶解して分離されることになる。
【００３５】
良溶媒を用いてコーティング剤をコーティングに適した濃度に希釈することが好ましい。必要に応じて、粘度調整剤等の添加剤を加えても良い。希釈溶媒としては、常圧下における沸点が100℃以下のものが好ましく、特にメタノール等のアルコール類が好ましく、固形分基準で10〜20％に希釈することが好ましい。
【００３６】
本発明のコーティング剤を被塗物に対して、固形分基準で１〜10g／ｍ²となるよう塗布することにより帯電防止性または導電性を付与できる。本発明のコーティング剤は金属板、プラスチック成型物、シートまたはフィルム、繊維、織布または不織布などのいずれにも適用でき、その表面に密着する。
【００３７】
[3] 導電性樹脂成型物
本発明の導電性樹脂成型物は、本発明の導電性グラフト重合体を成型することにより得られる。成型方法は特に限定されず、例えば導電性グラフト重合体をキャストすることによりフィルム状に成形してもよいし、熱と圧力をかけて成形する等、公知の方法により作成することができる。基盤等との密着性の観点からキャスト製膜する方法がもっとも好ましい。
【００３８】
キャストフィルムは、導電性グラフト重合体のメタノール溶液を調製し、これを水平に設置したガラス板上に流延し、キャストすることにより製造できる。必要に応じて、吸水性高分子、ゴム等をブレンドしてもよい。キャストフィルムの厚みは通常30〜500μm、好ましくは50〜200μm程度である。かくして得られる本発明の導電性樹脂成型物は、導電性の湿度依存性が小さく、乾燥下でも導電性が低下しにくいという特徴を有する。
【００３９】
なお、従来の導電性樹脂フィルムは、フィルムの機械的強度、耐水性、耐メタノール性において実用的な物性を得るため、クエン酸、酒石酸、次亜リン酸、パラトルエンスルホン酸などの架橋触媒や、メラミン樹脂、水溶性エポキシ樹脂などの架橋剤を用いて架橋したり、ベーキング処理を施す必要があったが、本発明の導電性樹脂成型物は上記のような架橋触媒や架橋剤を使用せずとも、また、ベーキングを省略したり、ベーキング温度を低くしても、あたかも架橋しているような耐熱水性、耐メタノール性を有するキャストフィルムを与えるものである。これは、リン酸基間の会合により見かけの架橋が生成することに起因すると考えられる。
【００４０】
【実施例】
以下に実施例を記載して本発明の内容をより具体的に説明するが、本発明はこれらに限定されるものではない。
【００４１】
内容積500ｍｌのステンレス製、強力マグネットスターラー付き反応器(ユニケミカル(株)製；特開平11-192422号）に、下記表１に記載の仕込み組成に従い、Ｎ-メトキシメチル化ナイロン-６（商品名「トレジンＦ30Ｋ」(メトキシメチル化度30％)、帝国化学産業（株）製）のメタノール溶液、リン酸基含有不飽和単量体、他の不飽和単量体、2,2'-アゾビスイソブチロニトリル（AIBN）を仕込み、還流冷却器、温度計、窒素吹込みノズルを備えた蓋をした。攪拌下で反応容器の外部からの電気ヒーターによる加熱により所定の重合温度63℃まで昇温させ、所定の反応時間３時間重合した。2,2'-アゾビスイソブチロニトリル（AIBN）を追加添加し、さらに1時間重合反応を行った。反応生成物が40℃以下まで降温するのを待って取出した。比較例１を除き、粘調な均一溶液状の生成物が得られた。
【００４２】
実験例１〜５では重合反応は問題無く推移し、透明で析出物のない粘性のある反応生成物溶液を得たが、比較例１では重合反応後、反応器の底に凝固物が沈殿した。反応生成物の回収量は反応器壁や攪拌器への付着物を完全に回収できなかったので、その分割り引いて考えなければならないが、反応生成物の固形分濃度の実測値を理論値（仕込みトレジンF30Kの重量と仕込み不飽和単量体の100％が重合した場合の重量の和）と比較して収率を計算したところ、比較例より実施例１〜５のほうが収率が高かった。
【００４３】
【表１】

【００４４】
ついで、得られた反応生成物を精製した。実施例１〜５と比較例１について、下記表２に記載の良溶媒、貧溶媒を用いてそれぞれ再沈精製を２回繰り返した後、貧溶媒で洗浄乾燥した。精製による物質収支を求め、精製前後の重合体の酸価（カルボン酸価＋リン酸価の和）を測定した。結果を表２に示す。
【００４５】
【表２】

【００４６】
表２に示した通り、貧溶媒として水を用いた場合はいずれも精製収率が70％以上と高いが、貧溶媒としてアセトンを用いた場合は精製収率が50％未満と低くなっている。精製前と精製後の酸価を比較すると、精製後のその値は明らかに低下している。この事実から、グラフト重合していない不飽和単量体の重合体が水またはアセトン中に流出したと推測できる。
【００４７】
しかしPhosmer類を単独でグラフトさせた実施例１、実施例２の場合も、メタクリル酸単独でグラフトさせた比較例１と比較して精製前後の酸価はそれほど遜色なく、また、実施例３〜５のようにPhosmer類とメタクリル酸の混合物をグラフト重合した場合は、前二者よりも精製前後の酸価が高くなることが判った。この事実から、Phosmer類がグラフトしているらしいことはより明瞭となり、更に、Phosmer類とメタクリル酸を混合してグラフト重合に供した方がグラフト効率が良くなることが判った。
【００４８】
次いで、実施例１と比較例１の精製グラフト重合体組成物を用いて、コーティング剤を調製した。コーティング剤の溶剤としては主としてメタノールを使用したが、コーティング剤Ｂ及びＣは粘度調整の意味で、メタノールの一部をポリエチレングリコール又はグリセリンで置き換えた。いずれの場合も沈殿を生じるようなことはなく、均一溶状を呈した。ここで得たコーティング剤を鋼板にコーティングし、40℃×２日間乾燥後、基材に対する密着性を定性的に評価した。結果を表３に示す。
【００４９】
【表３】

【００５０】
次いで、実施例１〜５及び比較例１の精製グラフト重合体組成物をそれぞれメタノールに固形分濃度20％に溶解し、架橋触媒、架橋剤を添加することなく、ガラス板上に流延して室温で２日間乾燥した後、ベーキング温度120℃で3分間熱処理し、厚さ約100μmのキャストフィルムを作成し、その外観、耐熱水性、耐メタノール性および表面固有抵抗を測定した。結果を表４に示す。
【００５１】
【表４】

【００５２】
表４の記載から明らかなように、Ｎ-メトキシメチル化ナイロン-６に対してメタクリル酸単独をグラフト重合した比較例１では原料のＮ-メトキシメチル化ナイロン-６（比較例２）よりも表面固有抵抗が高くなり、耐熱水性、耐メタノール性にも改良が見られないが、Phosmer類を単独で、もしくはメタクリル酸と混合してグラフト重合した実施例1〜５は、Ｎ-メトキシメチル化ナイロン-６そのもの（比較例２）並びにＮ-メトキシメチル化ナイロン-６にメタクリル酸単独をグラフト重合したもの（比較例１）に比べて、明らかに耐熱水性、耐メタノール性が改良されている。
【００５３】
ここで実施例１〜５のリン酸基含有不飽和単量体を含むグラフト重合体の場合だけが、キャストフィルムの作成過程でのベーキング温度が低くても、極端な例ではベーキングをしない場合にも、熱水およびメタノールに溶解し難い性質を示す。このことから、耐水性が向上した理由は、Ｎ-メトキシメチル化ナイロン-６の自己架橋が起こったことによるのではなく、リン酸基同士の分子間会合が効いていると考えられる。
【００５４】
また、実施例のリン酸基含有不飽和単量体を含むグラフト重合体の場合は、メタクリル酸のみのグラフト重合体（比較例１）および原料Ｎ-メトキシメチル化ナイロン-６そのもの（比較例２）に比べて、表面固有抵抗が少なくとも１桁低く、且つ、その環境湿度依存性の少ないことが判る。
【００５５】
【発明の効果】
以上詳述した通り、本発明によれば、リン酸基含有不飽和単量体を必須成分としてＮ - メトキシメチル化ナイロン - ６にグラフト重合することにより、架橋触媒、架橋剤の添加なしでも、耐熱水性、耐メタノール性に優れ、導電性の高い導電性グラフト重合体が得られる。
【００５６】
本発明の導電性グラフト重合体を用いたコーティング剤は各種基材に対する密着性に優れるとともに、耐熱水性、耐メタノール性に優れているので、電気・電子、繊維衣料用途向けの制電剤例えば導電性のロールへの被覆剤として、あるいはインク、塗料のビヒクルとして有効に用いられる。また、本発明の導電性グラフト重合体から得られる成型物は、フィルム強度が高く且つ導電性に優れるので、燃料電池等の高分子固体電解質として使用できる可能性を有する。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a conductive graft polymer obtained by radical polymerization using an unsaturated monomer containing a phosphate group as an essential component in the presence of a polyamide resin, a method for producing the same, and a water resistance, The present invention relates to a conductive graft polymer having excellent alcohol properties and antistatic properties, a method for producing the same, and a coating agent.
[0002]
[Prior art]
Conventionally, nylon-6, nylon-6,6, nylon-12, copolymer nylon, and the like are known as polyamide resins, and are widely used as clothing materials and molding materials. These have high volume resistivity and surface resistivity, and are electrical insulators (for example, the volume resistivity of nylon-12 is on the order of 10 ¹⁵ Ω · cm (30 ° C)), printer rollers, electrical / electronic components, ICs When used in fields such as heat-resistant trays and clothing, it is necessary to impart antistatic properties to the polyamide resin in order to prevent static electricity.
[0003]
For the purpose of lowering the electrical resistance of the polyamide resin and imparting antistatic properties, a method of mixing and dispersing a conductive filler such as carbon black fine particles in the polyamide resin is known (Japanese Patent Laid-Open Nos. 7-133711 and 5). -70685 etc.). However, it has been found that mixing carbon black or the like with a polyamide resin reduces the mechanical strength of the polyamide resin and leaves a problem with durability.
[0004]
A method of applying an antistatic coating agent made of a modified polyamide resin imparted with conductivity to a polyamide resin has been proposed. However, in general, polyamide resins have low solubility in solvents, and some products have been claimed to be soluble in a class of solvents called copolymer nylons with specific compositions, but there is a problem with the stability of the solution. Since there is no suitable solvent, it is not suitable for production of cast films and wet coating on the surface of the object to be coated.
[0005]
On the other hand, Japanese Patent Publication No. 7-25854 uses N-alkoxymethylated nylon that is soluble in alcohol by reacting nylon resin with formalin and alcohol to replace the hydrogen of the amide bond with an alkoxyalkyl group. Disclosure. In particular, N-methoxymethylated nylon-6 marketed by Teikoku Chemical Industry Co., Ltd. under the trade name resin has been reported to reduce the surface resistivity to the order of 10 ¹² Ω · cm to 10 ¹³ Ω · cm. .
[0006]
N-methoxymethylated nylon-6 has been evaluated for its good solubility and antistatic properties. For example, a plastic antistatic agent for electric and electronic applications (for example, JP-A-8-137186, JP-A-8-207428, JP-A-8-217619, JP-A-9-78012, JP-A-9-255992, JP-A-10-171212, JP-A-11-316470, JP-A-11-79966, etc.), vehicle of ink composition ( Japanese Patent Publication No. 9-175526, Japanese Patent Publication No. 11-140164, etc.) Exterior wall coating compositions (Japanese Patent Laid-Open Nos. 10-110136 and 10-140029), Run prevention agents for nylon stockings (Japanese Patent Laid-Open No. -67965) etc. have been proposed.
[0007]
However, although N-alkoxymethylated nylon is excellent in terms of antistatic effect and solubility, the water resistance and alcohol resistance of the coating film are weak, and the conductivity is easily affected by the humidity of the environment in a dry state. There was a problem that the antistatic effect was significantly reduced. In particular, when used in electrical and electronic applications such as printer rollers, problems have been pointed out that if the conductivity is affected by humidity, the surface of the roll is soiled by toner and the copy image is damaged.
[0008]
[Problems to be solved by the present invention]
Accordingly, an object of the present invention is to provide a conductive graft polymer that has excellent solvent solubility, has an antistatic effect that is stable regardless of humidity, and provides a film with excellent water resistance and alcohol resistance, and a method for producing the same And providing a coating agent.
[0009]
[Means for Solving the Problems]
As a result of intense research in view of the above problems, the present inventors have, (1) (A) under following general formula (I):
[Chemical 7]

[In the general formula (I), R ₁ represents H or CH ₃ , and R ₂ represents H, CH ₃ or CH ₂ X (X is halogen). n represents an integer of 1 to 6. The phosphoric acid group may be dissociated or may form a complex salt. A phosphoric acid group-containing unsaturated monomer represented by], (B) by the following formula (II):
[Chemical 8]

(. However, in the formula (II), l and m represent the polymerization ratio, 10 ≦ l ≦ 50, 50 ≦ m ≦ a 90, sum of l and m is 100) by represented by N - methoxymethylated nylon - mixture of 6 Prefecture, or (2) the phosphoric acid group-containing unsaturated monomer, the N - methoxymethylated nylon - 6, by radical polymerization of a mixture consisting of methacrylic acid The present invention has found that a conductive graft polymer that has excellent solvent solubility, has an antistatic effect that is stable regardless of humidity, and provides a film with excellent water resistance and alcohol resistance can be obtained. I came up with it.
[0010]
The conductive graft polymer of the present invention comprises N - methoxymethylated nylon - 6 and an unsaturated monomer having a phosphate group as essential components, and is heated and polymerized in the presence of a radical polymerization initiator in a solution state, In this case, at least a part of the unsaturated monomer is graft-polymerized with N - methoxymethylated nylon - 6 . That is, the present invention provides a reaction product obtained by radical polymerization of a mixture of a phosphate group-containing unsaturated monomer of the general formula (I) and N - methoxymethylated nylon - 6 of the formula (II) as an active ingredient. In the conductive graft polymer , at least a part of the general formula (I) is graft-polymerized to N - methoxymethylated nylon - 6 to obtain grafted N - methoxymethylated nylon - 6. Presumed to exist.
[0011]
The coating film obtained from the conductive graft polymer of the present invention is excellent in water resistance and alcohol resistance, which is considered to be due to association between phosphate groups. That is, when a phosphate group-containing unsaturated monomer is graft-polymerized to a polyamide resin, an apparent crosslink is generated due to the association between phosphate groups even if there is no covalent crosslink. Therefore, a crosslinking catalyst and a crosslinking agent are added. It is thought that it contributes to the improvement of water resistance from the research fact that it becomes a water-insoluble (swellable) gel (for example, Nakamae et al .; 35th Annual Meeting of Polymers (1989)).
[0012]
DETAILED DESCRIPTION OF THE INVENTION
[1] conductive graft polymer
(A) Polyamide resin The polyamide resin used in the present invention is not particularly limited as long as it has solubility in a solvent and can be graft-polymerized with a phosphate group-containing unsaturated monomer. The polyamide resin used in the present invention preferably has a molecular weight of 1,000 to 1,000,000, more preferably 2,000 to 500,000, and still more preferably 5,000 to 150,000. The polyamide resin preferably has 50 or more, more preferably 100 or more, sites capable of grafting in the molecule.
[0013]
Examples of the polyamide resin that can be preferably used in the present invention include polyamide resins represented by the following general formula (V) .
[Chemical 9]

[0014]
In the general formula (V) , R _{3 and} R ₄ each independently represents a substituted or unsubstituted alkylene group having 3 to 20 carbon atoms. Examples of the substituent include an alkyl group having 1 to 6 carbon atoms and halogen. R ₃ and R ₄ are preferably an unsubstituted alkylene group having 5 to 11 carbon atoms, more preferably n-pentylene.
[0015]
R ₅ represents a substituted or unsubstituted alkylene group having 1 to 6 carbon atoms. The substituent may be the same as R ₃ and R ₄ . Preferred R ₅ is methylene.
[0016]
R ₆ independently represents a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms. The substituent may be the same as R ₃ and R ₄ . Preferred R ₆ is methyl.
[0017]
l and m represent the polymerization ratio, and the sum of l and m is 100. 10 ≦ l ≦ 50 and 50 ≦ m ≦ 90 are preferable, and 20 ≦ l ≦ 30 and 70 ≦ m ≦ 80 are more preferable. If l is less than 10, the solvent solubility is lowered, which is not preferable. Even if l> 50 is aimed, it is difficult to exceed 50 due to the steric hindrance of the substituent.
[0018]
As the polyamide resin, the following formula (II) :
Embedded image

(. However, in the formula (II), l and m represent the polymerization ratio, 10 ≦ l ≦ 50, 50 ≦ m ≦ a 90, sum of l and m is 100) by represented by N - More preferred is methoxymethylated nylon - 6. Specific examples of the polyamide resin of the general formula (II) include Toresin F30K, Toresin MF-30 and Toresin EF-30T manufactured and sold by Teikoku Chemical Industry Co., Ltd.
[0019]
(B) Phosphoric acid group-containing unsaturated monomer The phosphoric acid group-containing unsaturated monomer used in the present invention is represented by the following general formula (I).
[Chemical 6]

[0020]
In the general formula (I), R ₁ represents H or CH ₃ , and R ₂ represents H, CH ₃ or CH ₂ X (X is halogen).
[0021]
The phosphoric acid group may be dissociated or may form a complex salt. In this case, in order to neutralize the charge, for example, ammonium ions containing primary, secondary, tertiary and quaternary alkyl groups, allyl groups, aralkyl groups, mono-, di- and trialkanolamine residues It is preferable to form a complex salt with a group, particularly N ⁺ R ⁷ _4-p (OH) _p (wherein is an alkyl group having 1 to 18 carbon atoms, an aromatic group having 6 to 12 carbon atoms, and 6 to 6 carbon atoms). Represents a group selected from 12 alicyclic groups, and p represents a positive integer of 1 to 3).
[0022]
n represents an integer of 1 to 6, preferably 4 to 6.
[0023]
Specific examples of the general formula (I) include Phosmer ^™ manufactured and sold by Unichemical Co., Ltd.
[0024]
[Chemical 7]

[0025]
Of these, Phosmer PP and Phosmer PE are particularly preferable.
[0026]
In addition to the phosphate group-containing unsaturated monomer of the general formula (I), another unsaturated monomer copolymerizable therewith may be used in combination. When other unsaturated monomers are used in combination, the [phosphoric acid group-containing unsaturated monomer] / [other unsaturated monomer] is 0.1 or more by weight, preferably 0.5 or more, more preferably 1 That's it.
[0027]
Other unsaturated monomers include those containing hydrophilic groups such as carboxylic acid groups, acid anhydride groups, hydroxyl groups, epoxy groups, ether groups, ester groups, amide groups, nitrile groups, and sulfonic acid groups in the molecule. There are a group (A) of saturated monomers and a group (B) that does not contain these hydrophilic groups. Specific examples of group (A) include (meth) acrylic acid, maleic anhydride, hydroxy (meth) acrylate, polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, methyl (meth) acrylate, vinyl acetate, dimethyl (Meth) acrylamide, diethyl (meth) acrylamide, (meth) acrylonitrile and the like can be mentioned. Specific examples of the group (B) include conjugated diolefins such as ethylenic monounsaturated hydrocarbons, vinyl chloride, various styrenes, and butadiene. It is preferable that the use ratio (A) / (B) of the monomer belonging to the group (A) and the monomer belonging to the group (B) is 1 or more by weight.
[0028]
(C) Graft polymerization Graft polymerization may be carried out according to a known method. For example, in a reaction system in which polyamide resin such as nylon-6 is dissolved, various unsaturated monomers are polymerized using a radical polymerization initiator to obtain a graft polymer (for example, Kosai et al. , Journal of the Chemical Society of Japan; 1975 (3) 523-526).
[0029]
Ratio of unsaturated monomer (sum of phosphate group-containing unsaturated monomer and other unsaturated monomer) to be graft polymerized to the polyamide resin as the skeleton [(unsaturated monomer) / (polyamide The resin)] is preferably in the range of 0.05 to 5 and more preferably 0.1 to 1 on a solids weight basis. When the ratio exceeds 5, graft polymerization is not effectively performed, and a relatively large amount of monomer-only polymer is generated. On the other hand, if it is less than 0.05, the degree of modification by graft polymerization becomes small and the purpose cannot be achieved.
[0030]
The unsaturated monomer may be added all at once in the initial stage of polymerization, or may be added in portions along the course of polymerization. When adding in a divided manner, it is preferable to mix and add a phosphoric acid group-containing unsaturated monomer and another unsaturated monomer from the viewpoint of homogenizing the composition of the graft polymer.
[0031]
The system for carrying out the graft polymerization is preferably a homogeneous solution system. Therefore, it is necessary to select a solvent that dissolves at least the polyamide resin and dissolve it in the solvent before it is used for graft polymerization. For example, when N-methoxymethylated nylon-6 (Toresin F30K, Teikoku Chemical Industry Co., Ltd.) is used as a polyamide resin, methanol, ethanol, isopropanol, ethylene glycol, polyethylene glycol, glycerin, ethyl cellosolve, Alcohol solvents such as butyl cellosolve are preferably used. The concentration of the polyamide resin in the solvent is preferably in the range of 5 to 50 wt%. The range of 10 to 25 wt% is particularly suitable from the viewpoint of solution viscosity.
[0032]
As radical polymerization initiators, 2,2-azobisisobutyronitrile, 2,2-azobis (2,4-dimethylvaleronitrile), dimethyl 2,2-azobis (2-methylpropionate), dimethyl-2 Depending on the desired polymerization reaction temperature, azo initiators such as 1,2-azobisisobutyrate and peroxide initiators such as benzoyl peroxide, lauroyl peroxide, and tertiary butyl peroxy pivalate Select and use. The amount used is in the range of 0.1 to 5 wt% with respect to the total of unsaturated monomers to be graft polymerized. This may be added all at once in the initial stage of polymerization, or a part thereof may be added in portions during the reaction process.
[0033]
Graft polymerization is performed by a usual method. For example, among a polyamide resin solution pre-dissolved in a reactor equipped with a stirrer and a reflux condenser, a reaction solvent, an initial addition of an unsaturated monomer mixture to be graft polymerized, and a polymerization initiator The initial addition is added and the temperature is raised to 40 ° C to 90 ° C, preferably 50 ° C to 80 ° C. The remainder of the unsaturated monomer mixture and the remainder of the polymerization initiator are added all at once or after a predetermined time in the reaction process. The reaction temperature does not need to be constant from the beginning to the end, and a method of increasing the temperature at the end of the polymerization and reducing the unreacted monomer as much as possible is often used.
[0034]
[2] Coating Agent The coating agent of the present invention uses the conductive graft polymer of the present invention. The conductive graft polymer may remain crude or may be purified. In the case of purification, the operation of once putting the reaction product into a poor solvent, precipitating the graft polymer, and then dissolving the precipitate in the good solvent again may be repeated. As the poor solvent, water is preferable, but when it does not precipitate in water, acetone or the like is used to precipitate the reaction product. The poor solvent is used in a large excess of 3 to 10 times the solid form of the reaction product. If a polymer of only unsaturated monomers that are not graft-polymerized to the polyamide resin is produced, it is soluble in (alcohol + water) solvent and (alcohol + acetone) solvent, so it is dissolved and separated on the liquid layer side. Will be.
[0035]
It is preferable to dilute the coating agent to a concentration suitable for coating using a good solvent. You may add additives, such as a viscosity modifier, as needed. As the dilution solvent, those having a boiling point of 100 ° C. or less under normal pressure are preferable, alcohols such as methanol are particularly preferable, and it is preferable to dilute to 10 to 20% based on the solid content.
[0036]
Antistatic property or electroconductivity can be provided by apply | coating the coating agent of this invention with respect to a to-be-coated article so that it may become 1-10 g / m < ² > on solid content basis. The coating agent of the present invention can be applied to any of a metal plate, a plastic molding, a sheet or film, a fiber, a woven fabric or a non-woven fabric, and is in close contact with the surface thereof.
[0037]
[3] Conductive resin molded article The conductive resin molded article of the present invention can be obtained by molding the conductive graft polymer of the present invention. The molding method is not particularly limited, and for example, it may be formed into a film by casting a conductive graft polymer, or may be prepared by a known method such as molding by applying heat and pressure. A cast film formation method is most preferable from the viewpoint of adhesion to a substrate or the like.
[0038]
The cast film can be produced by preparing a methanol solution of a conductive graft polymer , casting the solution on a horizontally placed glass plate, and casting. If necessary, a water-absorbing polymer, rubber or the like may be blended. The thickness of the cast film is usually about 30 to 500 μm, preferably about 50 to 200 μm. The conductive resin molded product of the present invention thus obtained has a characteristic that the conductivity is less dependent on humidity and the conductivity is not easily lowered even when dried.
[0039]
In addition, in order to obtain practical physical properties in the mechanical strength, water resistance, and methanol resistance of a conventional conductive resin film, a crosslinking catalyst such as citric acid, tartaric acid, hypophosphorous acid, paratoluenesulfonic acid, However, it was necessary to crosslink using a crosslinking agent such as a melamine resin or a water-soluble epoxy resin, or to perform a baking treatment. At least, even if the baking is omitted or the baking temperature is lowered, a cast film having hot water resistance and methanol resistance as if they are crosslinked is provided. This is thought to be due to the appearance of apparent cross-linking due to the association between phosphate groups.
[0040]
【Example】
Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto.
[0041]
N-methoxymethylated nylon-6 (commercial product) in a stainless steel reactor with an internal volume of 500 ml (manufactured by Unichemical Co., Ltd .; Japanese Patent Laid-Open No. 11-192422) according to the charging composition shown in Table 1 below Name "Toresin F30K" (Methoxymethylation degree 30%), Teikoku Chemical Industry Co., Ltd. methanol solution, phosphate group-containing unsaturated monomer, other unsaturated monomer, 2,2'-azo Bisisobutyronitrile (AIBN) was charged, and a lid equipped with a reflux condenser, a thermometer, and a nitrogen blowing nozzle was used. Under stirring, the temperature was raised to a predetermined polymerization temperature of 63 ° C. by heating with an electric heater from the outside of the reaction vessel, and polymerization was performed for a predetermined reaction time of 3 hours. 2,2′-Azobisisobutyronitrile (AIBN) was additionally added, and the polymerization reaction was further carried out for 1 hour. The reaction product was taken out after cooling to 40 ° C. or lower. Except for Comparative Example 1, a viscous uniform solution-like product was obtained.
[0042]
In Experimental Examples 1 to 5, the polymerization reaction progressed without any problem, and a viscous reaction product solution without deposits was obtained. In Comparative Example 1, after the polymerization reaction, a solidified product precipitated at the bottom of the reactor. . The amount of reaction product recovered could not be completely collected on the reactor wall and the stirrer, so it must be subdivided, but the measured solid value of the reaction product is the theoretical value ( When the yield was calculated in comparison with the weight of the charged resin F30K and the weight when 100% of the charged unsaturated monomer was polymerized, the yields of Examples 1 to 5 were higher than those of the comparative examples. .
[0043]
[Table 1]

[0044]
Subsequently, the obtained reaction product was purified. For Examples 1 to 5 and Comparative Example 1, reprecipitation purification was repeated twice using the good solvent and the poor solvent described in Table 2 below, and then washed and dried with the poor solvent. The mass balance by purification was determined, and the acid value (the sum of carboxylic acid value + phosphoric acid value) of the polymer before and after purification was measured. The results are shown in Table 2.
[0045]
[Table 2]

[0046]
As shown in Table 2, the purification yield is as high as 70% or more when water is used as the poor solvent, but the purification yield is as low as less than 50% when acetone is used as the poor solvent. . When the acid value before and after purification is compared, the value after purification is clearly reduced. From this fact, it can be inferred that the polymer of the unsaturated monomer which has not been graft-polymerized flows into water or acetone.
[0047]
However, in the case of Example 1 and Example 2 grafted with Phosmers alone, the acid value before and after purification was not so different from that in Comparative Example 1 grafted with methacrylic acid alone. In the case of graft polymerization of a mixture of Phosmer and methacrylic acid as in 5, it was found that the acid value before and after purification was higher than the former two. From this fact, it became clear that the Phosmers seem to be grafted, and it was further found that the graft efficiency was improved when the Phosmers and methacrylic acid were mixed and subjected to graft polymerization.
[0048]
Next, a coating agent was prepared using the purified graft polymer compositions of Example 1 and Comparative Example 1. Although methanol was mainly used as the solvent for the coating agent, coating agents B and C were partially substituted with polyethylene glycol or glycerin for the purpose of viscosity adjustment. In either case, no precipitation occurred and a homogeneous solution was exhibited. The coating agent obtained here was coated on a steel plate, dried at 40 ° C. for 2 days, and then qualitatively evaluated for adhesion to the substrate. The results are shown in Table 3.
[0049]
[Table 3]

[0050]
Next, the purified graft polymer compositions of Examples 1 to 5 and Comparative Example 1 were each dissolved in methanol at a solid content concentration of 20%, and cast on a glass plate without adding a crosslinking catalyst and a crosslinking agent. After drying at room temperature for 2 days, heat treatment was performed at a baking temperature of 120 ° C. for 3 minutes to prepare a cast film having a thickness of about 100 μm, and its appearance, hot water resistance, methanol resistance and surface resistivity were measured. The results are shown in Table 4.
[0051]
[Table 4]

[0052]
As is apparent from the description in Table 4, the surface of Comparative Example 1 in which methacrylic acid alone was graft-polymerized with N-methoxymethylated nylon-6 was more surface than the raw material N-methoxymethylated nylon-6 (Comparative Example 2). Although specific resistance becomes high and improvement in hot water resistance and methanol resistance is not observed, Examples 1 to 5 obtained by graft polymerization using Phosmers alone or mixed with methacrylic acid are N-methoxymethylated nylon. Compared to -6 itself (Comparative Example 2) and N-methoxymethylated nylon-6 obtained by graft polymerization of methacrylic acid alone (Comparative Example 1), the hot water resistance and methanol resistance are clearly improved.
[0053]
Here, only in the case of the graft polymer containing the phosphate group-containing unsaturated monomer of Examples 1 to 5, even when the baking temperature in the process of forming the cast film is low, in an extreme example, when baking is not performed Also, it exhibits a property that it is difficult to dissolve in hot water and methanol. From this, it is considered that the reason why the water resistance is improved is not due to the occurrence of self-crosslinking of N-methoxymethylated nylon-6, but the intermolecular association between phosphate groups is effective.
[0054]
Further, in the case of the graft polymer containing the phosphate group-containing unsaturated monomer of the examples, the graft polymer of only methacrylic acid (Comparative Example 1) and the raw material N-methoxymethylated nylon-6 itself (Comparative Example 2) It can be seen that the surface resistivity is at least an order of magnitude lower and less dependent on environmental humidity.
[0055]
【The invention's effect】
As described in detail above, according to the present invention, by graft-polymerizing a phosphate group-containing unsaturated monomer as an essential component to N - methoxymethylated nylon - 6 , without the addition of a crosslinking catalyst or crosslinking agent, A conductive graft polymer having excellent hot water resistance and methanol resistance and high conductivity can be obtained.
[0056]
The coating agent using the conductive graft polymer of the present invention has excellent adhesion to various substrates, and has excellent hot water resistance and methanol resistance. It is effectively used as a coating agent for a conductive roll or as a vehicle for ink or paint. Moreover, since the molding obtained from the electroconductive graft polymer of this invention has high film strength and is excellent in electroconductivity, it has a possibility that it can be used as polymer solid electrolytes, such as a fuel cell.

Claims (6)

(1) (A) under following general formula (I):

[In the general formula (I), R ₁ represents H or CH ₃ , and R ₂ represents H, CH ₃ or CH ₂ X (X is halogen). n represents an integer of 1 to 6. The phosphoric acid group may be dissociated or may form a complex salt. A phosphoric acid group-containing unsaturated monomer represented by], (B) by the following formula (II):

(. However, in the formula (II), l and m represent the polymerization ratio, 10 ≦ l ≦ 50, 50 ≦ m ≦ a 90, sum of l and m is 100) by represented by N - methoxymethylated nylon - mixture of 6 Prefecture, or (2) with the phosphoric acid group-containing unsaturated monomer, the N - methoxymethylated nylon - 6, by radical polymerization of a mixture of methacrylic acid obtained A conductive graft polymer . The conductive graft polymer according to claim 1, wherein the phosphate group-containing unsaturated monomer is represented by the following formula: (III) :

(However, n Represents 4 or 5), or the following formula (IV) :

(However, n Represents an integer of 4 to 6), and a conductive graft polymer. A coating agent comprising the conductive graft polymer according to claim 1.   A method for forming a coating film on a steel material, glass, plastic, or fiber using the coating agent according to claim 3. A film formed by casting the conductive graft polymer according to claim 1 or 2. (1) The following formula (II) :

(. However, in the formula (II), l and m represent the polymerization ratio, 10 ≦ l ≦ 50, 50 ≦ m ≦ a 90, sum of l and m is 100) by represented by N - In a solution of methoxymethylated nylon - 6 dissolved in a solvent, the following general formula (I):

[In the general formula (I), R ₁ represents H or CH ₃ , and R ₂ represents H, CH ₃ or CH ₂ X (X is halogen). n represents an integer of 1 to 6. The phosphoric acid group may be dissociated or may form a complex salt. Or a radical polymerization initiator and a radical polymerization reaction, or (2) the phosphate group-containing solution is added to the N - methoxymethylated nylon - 6 solution. A method for producing a conductive graft polymer , comprising adding an unsaturated monomer , methacrylic acid, and a radical polymerization initiator to cause radical polymerization reaction.