JP2004026928A

JP2004026928A - Synthetic rubber latex

Info

Publication number: JP2004026928A
Application number: JP2002182787A
Authority: JP
Inventors: Keigo Yoshikawa; 吉川　圭吾; Yoichi Higashide; 東出　陽一; Shinzo Ihata; 井幡　伸三
Original assignee: Dainippon Ink and Chemicals Co Ltd
Current assignee: DIC Corp
Priority date: 2002-06-24
Filing date: 2002-06-24
Publication date: 2004-01-29

Abstract

<P>PROBLEM TO BE SOLVED: To provide a synthetic rubber latex for a binder for synthetic fibers, pulp fibers, etc., excellent in wet strength without using a large amount of a formalin-releasing substance. <P>SOLUTION: The latex is prepared by polymerizing an unsaturated monomer mixture comprising (a) a methylol derivative of an ethylenically unsaturated carboxylic acid amide, (b) an ethylenically unsaturated carboxylic acid amide, and (c) an aliphatic diene monomer, provided that 3 ≥ weight ratio (a)/(b) ≥ 0.15 and that the sum of amounts of (a) and (b) is 1-10 wt% based on the total amount of the unsaturated monomer mixture. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、繊維用バインダーに用いられる合成ゴムラテックスに関するもので、さらに詳細には、パルプ繊維、合成繊維等の湿潤引っ張り強度を著しく向上させ、且つ遊離ホルマリン量を低減した繊維用バインダー、パルプ不織布用途に使用される合成ゴムラテックスに関するものである。
【０００２】
【従来の技術】
従来、合成繊維、パルプ繊維等のバインダー用途には、合成ゴムラテックスが使用されているが、湿潤時の強度（湿潤強度）が不足する問題点があった。その改善策として、特開２００１−１１７６６号公報には、エチレン系不飽和カルボン酸アミドのメチロール誘導体を合成ゴムラテックスへ導入することよる湿潤強度の向上策が提案されていた。しかし、前記の湿潤強度の向上策では、エチレン系不飽和カルボン酸アミドのメチロール誘導体から、遊離した多量のホルマリンが発生し、衛生上の問題がある。例えば、乳幼児における衣類からホルマリン遊離量は吸光度で０．０５以下（ＪＩＳ　Ｌ１０６１記載の方法において）にしなければならないといった規制があり、繊維業界においても一般的基準となっている。そのため、前記の方法で、ホルマリン遊離量を低減するには、エチレン系不飽和カルボン酸アミドのメチロール誘導体の導入量を低減するか、或いは、後述するホルマリンキャッチャーを多量に添加することが必要となり、何れの場合も、湿潤強度が低下する。従って、湿潤時の強度（湿潤強度）低下の改善策とホルマリン遊離量の低減策の両方を満足する合成ゴムラテックスは、見出されていなかった。
【０００３】
【発明の解決しようとする課題】
本発明の課題は、ホルマリン遊離量を大幅に低減して、ホルマリンキャッチャー添加量が少なくても、上記エチレン系不飽和カルボン酸アミドのメチロール誘導体を導入して湿潤強度を向上させたものと同等の湿潤強度を有する合成ゴムラテックスを提供することである。
【０００４】
【課題を解決するための手段】
本発明者らは、上記課題を解決するために、鋭意検討した結果、エチレン系不飽和カルボン酸アミドを必須成分とした特定の単量体組成を乳化重合してなる合成ゴムラテックスが、前記課題解決となることを見出し、本発明に至った。
【０００５】
即ち、本発明は、エチレン系不飽和カルボン酸アミドのメチロール誘導体（ａ）とエチレン系不飽和カルボン酸アミド（ｂ）と脂肪族ジエン単量体（ｃ）とを含有する不飽和単量体混合物を重合して得られる合成ゴムラテックスであって、エチレン系不飽和カルボン酸アミドのメチロール誘導体（ａ）とエチレン系不飽和カルボン酸アミド（ｂ）との配合比が３≧（ａ）／（ｂ）≧０．１５（重量比）、且つ、（ａ）と（ｂ）の合計重量が不飽和単量体混合物の総重量の１〜１０重量％であることを特徴とする合成ゴムラテックスを提供する。
【０００６】
【発明の実施の形態】
本発明の合成ゴムラテックスは、前記エチレン系不飽和カルボン酸アミドのメチロール誘導体（ａ）とエチレン系不飽和カルボン酸アミド（ｂ）と脂肪族ジエン単量体（ｃ）からなる不飽和単量体類、必要に応じてエチレン系不飽和カルボン酸単量体（ｄ）または、前記（ａ）〜（ｄ）以外の共重合可能なビニル化合物（ｅ）等を加えた不飽和単量体類を後述する方法で、乳化重合して得た樹脂の水分散体である。
【０００７】
本発明の合成ゴムラテックスに使用されるエチレン系不飽和カルボン酸アミドのメチロール誘導体（ａ）としては、例えば、Ｎ−メチロールアクリルアミド、Ｎ−メチロールメタアクリルアミドなどが挙げられるが、好ましくはＮ−メチロールアクリルアミドである。
【０００８】
本発明の合成ゴムラテックスに使用されるエチレン系不飽和カルボン酸アミド（ｂ）としては、アクリルアミド、メタアクリルアミド及びＮ−ブトキシメチルアクリルアミド等が挙げられるが、好ましくはアクリルアミドである。
【０００９】
前記エチレン系不飽和カルボン酸アミドのメチロール誘導体（ａ）とエチレン系不飽和カルボン酸アミド（ｂ）との配合比が、３≧（ａ）／（ｂ）≧０．１５（重量比）であることが必要である。前記の範囲の中でも２≧（ａ）／（ｂ）≧０．２５（重量比）であることが特に好ましい。ここで、（ａ）／（ｂ）の値が０．１５未満（重量比）の場合は、合成ゴムラテックスの湿潤強度が低下し好ましくない。また、（ａ）／（ｂ）の値が３（重量比）を超える場合は、ホルマリン遊離量が、前述のＪＩＳ　Ｌ１０６１記載の方法で測定した吸光度が０．０５を超える程度まで増大するため好ましくない。
【００１０】
前記エチレン系不飽和カルボン酸アミドのメチロール誘導体（ａ）及びエチレン系不飽和カルボン酸アミド（ｂ）の合成ゴムラテックス全重量当たりの配合量は、（ａ）と（ｂ）の合計重量が不飽和単量体混合物の総重量の１〜１０重量％となることが必要である。ここで、（ａ）と（ｂ）の合計重量が１重量％未満の場合は、合成ゴムラテックスの湿潤強度が低下し好ましくない。また、１０重量％を超えると乳化重合中の凝集物（たとえば、ゲル物など）発生量が著しく多くなり、好ましくない。前記の範囲の中でも、不飽和単量体混合物の総重量の１〜６重量％となることが特に好ましい。
【００１１】
前記共役ジエン系単量体（ｃ）としては、例えば、１，３−ブタジエン、イソプレン、２−クロル−１，３−ブタジエンなどが挙げられるが、これらの内、１，３−ブタジエンが好ましく、その使用量は、単量体総重量の１０〜５０重量％の範囲が好ましい。
【００１２】
また、本発明の合成ゴムラテックスを製造する際には、必要に応じて、エチレン系不飽和カルボン酸単量体（ｄ）が使用できるが、該エチレン系不飽和カルボン酸単量体（ｄ）としては、例えば、イタコン酸、フマル酸、マレイン酸、メタアクリル酸、アクリル酸及びジカルボン酸のハーフエステル類等が挙げられるが、好ましくは、アクリル酸、メタアクリル酸、イタコン酸である。またこれらエチレン系不飽和カルボン酸単量体の１種類または複数使用しても構わず、その使用量は、ラテックスの機械的強度が充分発現することから前記単量体類総重量の０．５重量％以上が好ましく、合成ゴムラテックスが増粘しにくいことから１０重量％以下が好ましい。
【００１３】
また、本発明の合成ゴムラテックスを製造する際には、必要に応じて、前記（ａ）〜（ｄ）以外の共重合可能なビニル化合物（ｅ）が使用できる。前記ビニル化合物（ｅ）としては、例えば、スチレン、α−メチルスチレン、クロルスチレン、ビニルトルエン、メタアクリロニトリル、アクリロニトリル、メタアクリル酸メチル、メタアクリル酸プロピル、ヒドロキシエチルメタアクリレート、メタアクリル酸−２−エチルヘキシル、メタアクリル酸ラウリル、アクリル酸メチル、アクリル酸エチル、アミノエチルメタアクリレート、ジメチルアミノエチルメタアクリレート、ジエチルアミノエチルメタアクリレート、アクリル酸ブチル、アクリル酸２−エチルヘキシル、アクリル酸２−エチルヘキシルヒドロキシエチルアクリレート、アミノエチルアクリレート、ジメチルアミノエチルアクリレート、ジエチルアミノエチルアクリレート等が挙げられ、最も好ましくはスチレンであり、その使用量は、単量体類の総重量の３０〜８０重量％が好ましく、特に４０〜７０重量％が好ましい。
【００１４】
本発明の合成ゴムラテックスを乳化重合して得る際に使用する重合開始剤としては、特に限定されないが、例えば、過硫酸カリウム、過硫酸ナトリウム、過硫酸アンモニウム等の過硫酸塩系開始剤、クメンハイドロパーオキサイド、ジイソプロピルベンゼンハイドロパーオキサイド、ベンゾイルパーオキサイド等の有機過酸化物、過酸化水素等を挙げられる。
【００１５】
また、乳化重合を促進させるために、亜硫酸ナトリウム、亜硫酸水素ナトリウム、硫酸第一鉄、グルコース、ホルムアルデヒド、Ｌ−アスコルビン酸、ナトリウムスルホキシレート等の還元剤、グリシン、アラニン、エチレンジアミン四酢酸アンモニウム塩等のキレート剤を併用しても良い。
【００１６】
乳化重合に使用する乳化剤としては、反応性界面活性剤を含めた通常のアニオン性界面活性剤、ノニオン性界面活性剤等であり、何ら限定するものではない。
【００１７】
本発明の合成ゴムラテックスは、前記の単量体組成をベースとするが、任意の分子量にするために、重合時に連鎖移動剤及び重合停止剤等の分子量調整剤または重合率調整剤を適宜使用することができる。更に冷却による反応中断により分子量のコントロールを行っても良い。また粒子径をコントロールすべく、適当なラテックスを用いてシード重合を行っても構わない。
【００１８】
また、連鎖移動剤としては、例えば、通常の重合で使用されるものを使用することができる、たとえばｔ−ドデシルメルカプタン、ｎ−トデシルメルカプタン、オクチルメルカプタン、ｎ−テトラデシルメルカプタン、ｎ−ヘキシルメルカプタン等のメルカプタン類、ターピノーレン、ｔ−テルピネン、α−メチルスチレンダイマー、エチルキサントゲンジスルフィド、ジイソプロピルキサントゲンスルフィド、アミノフェニルスルフィド、テトラエチルチウラムジスルフィド等が挙げられ、これらの１種又は２種以上を使用することができる。
【００１９】
また、重合停止剤としては、例えばハイドロキノン（フェノール）系、アミン系、硫黄系、硫酸ヒドロキシルアミン、アンモニア、苛性ソーダ、苛性カリ等が挙げられ、またその他重合停止効果のあるものが使用でき、更にこれらを複数併用しても良い。その使用量は重合禁止剤の種類及び単量体との反応性比により異なる。
【００２０】
本発明の合成ゴムラテックスの重合方法としては、たとえば、前記単量体（ａ）、（ｂ）、（ｃ）、（ｄ）、及び（ｅ）を一括添加して、１段の乳化重合反応を行って樹脂を得る方法（以下、１段重合と記す。）、或いは前記単量体（ａ）、（ｃ）、（ｄ）、及び（ｅ）を乳化重合して得られる重合体（Ｉ）の存在下で、（ｂ）を必須成分として、必要に応じて（ｃ）、及び（ｅ）の混合物を重合して樹脂（ＩＩ）を得る方法（以下、２段重合と記す。）等が挙げられる。
【００２１】
前記２種類の方法のうちでは、アミド基がラテックス粒子表面に局在化し、湿潤強度への寄与が多くなることから、１段重合よりも２段重合の方が、好ましい。
【００２２】
前記乳化重合方法では、前記の単量体混合物を、乳化剤、重合開始剤、重合促進剤、連鎖移動剤、塩基性化合物の存在下で、４５℃〜９０℃で重合を行う。この際、前記の１段の乳化重合反応、２段重合についても、条件については同様である。
【００２３】
また、乳化重合は、上記重合乳化剤、連鎖移動剤、重合開始剤、重合禁止剤等の他、必要に応じて各種電解質、ｐＨ調製剤等を併用して種々の方法で行えば良い。
【００２４】
本発明の合成ゴムラテックスは、不揮発分３０〜７０重量％であることが、取り扱いの点から好ましいが、必要に応じ、水、水溶性の溶媒等で希釈して使用することができる。
【００２５】
また本発明の合成ゴムラテックスには、尿素、エチレン尿素、ジシアンジアミド、塩酸ヒドロキシルアミン等のホルマリンキャッチャーを重合時添加または重合終了後に適量加えることができる。その他、その使用目的に応じて以下の配合資材を加えても構わない。
【００２６】
本発明の合成ゴムラテックスに加えても良い添加剤としては、例えば、吸水剤、無機顔料、有機顔料等の着色剤、キレート剤、分散剤、酸化防止剤、紫外線吸収剤、界面活性剤、圧縮回復剤、消泡剤、殺菌剤、防腐剤、湿潤剤、メラミン系を除く架橋剤、酸化亜鉛・硫黄・加硫促進剤等の加硫剤、タック防止剤、起泡剤、整泡剤、浸透剤、撥水・撥油剤・ブロッキング防止剤、難燃剤、充填剤、増粘剤等を挙げることができ。前記ホルマリンキャッチャー或いは前記添加剤の選択、添加量、添加順序等は、ＳＢＲラテックス１００重量部に対して０．０００１重量部〜１０重量部の範囲添加することが好ましいが、ラテックスの製造条件、作業性、安定性、更に加工適性、塗布量等を考慮して、適宜に決定されれば良い。
【００２７】。
【実施例】
以下に実施例を挙げて本発明を説明するが、実施例及び表中における部及び％は特に断らない限り、重量基準である。
実施例１〜６
蒸留水１３０部、重合乳化剤１．５部、ｔ−ドデシルメルカプタン０．２部及びブタジエン、スチレン、Ｎ−メチロールアクリルアミド、アクリルアミド及びアクリル酸の単量体を表１に示す様、オートクレーブ内に仕込み、６０℃に昇温後、過硫酸アンモニウム０．３部を仕込み１０時間反応を行った。反応終了後、アンモニアでｐＨを８．０以上に調整、ストリッピングを行い、尿素２部添加し、アンモニアでｐＨ７．５〜８．０に調整し、合成ゴムラテックス１〜６を得た。このラテックスを５％に希釈し、Ｎｏ．２濾紙（東洋濾紙製）に樹脂付着量が１７％になる様、含浸後、マングルロールで付着量を調整した。得られた含浸濾紙を１４０℃で１０分間乾燥し、幅１．５ｃｍ×長さ１５ｃｍの試片に切り取り、常態及び湿潤時の引っ張り強度測定用試片とした。湿潤引っ張り強度は、２５℃の水中に１時間浸漬後測定した。また、残りの試片を２．５ｇ精秤し、ＪＩＳＬ　１０４１（Ａ法：アセチルアセトン法）に従い、遊離ホルマリン量（吸光度）の測定を行った。但し吸光度０．０５以下は検出限界とする。
【００２８】
実施例７〜１２
蒸留水１３０部、重合乳化剤１．５部、ｔ−ドデシルメルカプタン０．２部及びブタジエン、スチレン、Ｎ−メチロールアクリルアミド、アクリルアミド、アクリル酸及びイタコン酸の単量体を表２に示す様、オートクレーブ内に仕込み、６０℃に昇温後、過硫酸アンモニウム０．３部を仕込み８〜１０時間反応を行い、反応終了後、アンモニアでｐＨを８．０以上に調整、ストリッピングを行い、尿素２部添加し、アンモニアでｐＨ７．５〜８．０に調整し、合成ゴムラテックス７〜１２を得た。このラテックスを５％に希釈し、Ｎｏ．２濾紙（東洋濾紙製）に樹脂付着量が１７％になる様、含浸後、マングルロールで付着量を調整した。得られた含浸濾紙を１４０℃で１０分間乾燥し、幅１．５ｃｍ×長さ１５ｃｍの試片に切り取り、常態及び湿潤時の引っ張り強度測定用試片とした。湿潤引っ張り強度は、２５℃の水中に１時間浸漬後測定した。また残りの試片を２．５ｇ精秤し、ＪＩＳ　Ｌ　１０４１（Ａ法：アセチルアセトン法）に従い、遊離ホルマリン量（吸光度）の測定を行った。但し、吸光度０．０５以下は検出限界とする。
【００２９】
実施例１３〜１８
蒸留水１３０部、重合乳化剤１．５部、ｔ−ドデシルメルカプタン０．２部及びブタジエン、スチレン、Ｎ−メチロールアクリルアミド及びアクリル酸の単量体を表３に示す様、オートクレーブ内に仕込み、６０℃に昇温後、過硫酸アンモニウム０．３部を仕込み８〜１０時間反応を行う。得られたラテックスに、表３に示す様、アクリルアミド、スチレン、ブタジエン及び過硫酸アンモニウム０．２部を加え、更に６５℃で６〜８時間反応を行った。反応終了後、アンモニアでｐＨを８．０以上に調整、ストリッピングを行い、尿素２部添加し、アンモニアでｐＨ７．５〜８．０に調整し、合成ゴムラテックス１３〜１８を得た。このラテックスを５％に希釈し、Ｎｏ．２濾紙（東洋濾紙製）に樹脂付着量が１７％になる様、含浸後、マングルロールで付着量を調整した。得られた含浸濾紙を１４０℃で１０分間乾燥し、幅１．５ｃｍ×長さ１５ｃｍの試片に切り取り、常態及び湿潤時の引っ張り強度測定用試片とした。湿潤引っ張り強度は、２５℃の水中に１時間浸漬後測定した。また残りの試片を２．５ｇ精秤し、ＪＩＳ　Ｌ　１０４１（Ａ法：アセチルアセトン法）に従い、遊離ホルマリン量（吸光度）の測定を行った。但し、吸光度０．０５以下は検出限界とする。
【００３０】
比較例１〜５
蒸留水１３０部、重合乳化剤１．５部、ｔ−ドデシルメルカプタン０．２部及びブタジエン、スチレン、Ｎ−メチロールアクリルアミド、アクリルアミド及びアクリル酸の単量体を表４に示す様、オートクレーブ内に仕込み、６０℃に昇温後、過硫酸アンモニウム０．３部を仕込み１０時間反応を行った。反応終了後、アンモニアでｐＨを８．０以上に調整、ストリッピングを行い、尿素２部添加し、アンモニアでｐＨ７．５〜８．０に調整し、合成ゴムラテックス１９〜２４を得た。このラテックスを５％に希釈し、Ｎｏ．２濾紙（東洋濾紙製）に樹脂付着量が１７％になる様、含浸後、マングルロールで付着量を調整した。得られた含浸濾紙を１４０℃で１０分間乾燥し、幅１．５ｃｍ×長さ１５ｃｍの試片に切り取り、常態及び湿潤時の引っ張り強度測定用試片とした。湿潤引っ張り強度は、２５℃の水中に１時間浸漬後測定した。また、残りの試片を２．５ｇ精秤し、ＪＩＳ　Ｌ　１０４１（Ａ法：アセチルアセトン法）に従い、遊離ホルマリン量（吸光　度）の測定を行った。但し吸光度０．０５以下は検出限界とする。
【００３１】
比較例６〜１１
蒸留水１３０部、重合乳化剤１．５部、ｔ−ドデシルメルカプタン０．２部及びブタジエン、スチレン、Ｎ−メチロールアクリルアミド及びアクリル酸の単量体を表５に示す様、オートクレーブ内に仕込み、６０℃に昇温後、過硫酸アンモニウム０．３部を仕込み８〜１０時間反応を行う。得られたラテックスに、表５に示す様、アクリルアミド、スチレン、ブタジエン及び過硫酸アンモニウム０．２部を加え、更に６５℃で６〜８時間反応を行った。反応終了後、アンモニアでｐＨを８．０以上に調整、ストリッピングを行い、尿素２部添加し、アンモニアでｐＨ７．５〜８．０に調整し、合成ゴムラテックス２５〜３０を得た。このラテックスを５％に希釈し、Ｎｏ．２濾紙（東洋濾紙製）に樹脂付着量が１７％になる様、含浸後、マングルロールで付着量を調整した。得られた含浸濾紙を１４０℃で１０分間乾燥し、幅１．５ｃｍ×長さ１５ｃｍの試片に切り取り、常態及び湿潤時の引っ張り強度測定用試片とした。湿潤引っ張り強度は、２５℃の水中に１時間浸漬後測定した。また残りの試片を２．５ｇ精秤し、ＪＩＳ　Ｌ　１０４１（Ａ法：アセチルアセトン法）に従い、遊離ホルマリン量（吸光度）の測定を行った。但し、吸光度０．０５未満は検出限界とする。
【００３２】
なお、表中の含浸紙の判定は、含浸紙の常態強度が１７Ｍｐａ以上、かつ湿潤強度が８Ｍｐａ以上を合格（○）とし、これらの中でも、湿潤強度が８Ｍｐａ以上のものを◎で示し、含浸紙の常態強度が１７Ｍｐａ未満、または湿潤強度が８Ｍｐａ未満のものを不合格（×）とした。また、ホルマリン遊離量の判定は、遊離ホルマリン量（吸光度）０．０５以下の場合に合格（○）、０．０５超を不合格（×）とした。
【００３３】
【表１】

【００３４】
【表２】

【００３５】
【表３】

【００３６】
【表４】

【００３７】
【表５】

【００３８】
【発明の効果】
本発明によれば、パルプ繊維、合成繊維等の湿潤引っ張り強度を著しく向上させ、且つ遊離ホルマリン量を低減した繊維用バインダー、パルプ不織布用途に使用される合成ゴムラテックスを提供できる。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a synthetic rubber latex used for a fiber binder, and more particularly, a pulp non-woven fabric, a pulp non-woven fabric, a pulp non-woven fabric, a pulp fiber, a synthetic fiber having a significantly improved wet tensile strength and a reduced amount of free formalin. It relates to a synthetic rubber latex used for applications.
[0002]
[Prior art]
Conventionally, synthetic rubber latex has been used for binder applications such as synthetic fibers and pulp fibers, but there has been a problem that the strength when wet (wet strength) is insufficient. As an improvement measure, Japanese Patent Application Laid-Open No. 2001-11766 has proposed a measure for improving the wet strength by introducing a methylol derivative of an ethylenically unsaturated carboxylic acid amide into a synthetic rubber latex. However, in the above-mentioned measures for improving the wet strength, a large amount of free formalin is generated from the methylol derivative of the ethylenically unsaturated carboxylic acid amide, and there is a problem in hygiene. For example, there is a regulation that the amount of formalin released from clothing in infants and children must be 0.05 or less in absorbance (in the method described in JIS L1061), which is a general standard in the textile industry. Therefore, in the method described above, in order to reduce the amount of formalin released, it is necessary to reduce the amount of introduction of the methylol derivative of the ethylenically unsaturated carboxylic acid amide, or to add a large amount of formalin catcher described below, In either case, the wet strength is reduced. Therefore, a synthetic rubber latex that satisfies both a measure for reducing the strength when wet (wet strength) and a measure for reducing the amount of released formalin has not been found.
[0003]
[Problems to be solved by the invention]
The object of the present invention is to substantially reduce the amount of formalin released and, even with a small amount of formalin catcher, to improve the wet strength by introducing the methylol derivative of the ethylenically unsaturated carboxylic acid amide to improve the wet strength. It is to provide a synthetic rubber latex having wet strength.
[0004]
[Means for Solving the Problems]
The present inventors have conducted intensive studies to solve the above problems, and as a result, a synthetic rubber latex obtained by emulsion polymerization of a specific monomer composition containing an ethylenically unsaturated carboxylic acid amide as an essential component, The inventors have found that this is a solution, and have reached the present invention.
[0005]
That is, the present invention provides an unsaturated monomer mixture containing an ethylenically unsaturated carboxylic acid amide methylol derivative (a), an ethylenically unsaturated carboxylic acid amide (b) and an aliphatic diene monomer (c). Is a synthetic rubber latex obtained by polymerizing the compound, wherein the compounding ratio of the ethylenically unsaturated carboxylic acid amide methylol derivative (a) and the ethylenically unsaturated carboxylic acid amide (b) is 3 ≧ (a) / (b) ) ≧ 0.15 (weight ratio) and the total weight of (a) and (b) is 1 to 10% by weight of the total weight of the unsaturated monomer mixture. I do.
[0006]
BEST MODE FOR CARRYING OUT THE INVENTION
The synthetic rubber latex of the present invention comprises an unsaturated monomer comprising the methylol derivative of the ethylenically unsaturated carboxylic acid amide (a), the ethylenically unsaturated carboxylic acid amide (b) and the aliphatic diene monomer (c). And, if necessary, an unsaturated monomer to which an ethylenically unsaturated carboxylic acid monomer (d) or a copolymerizable vinyl compound (e) other than the above (a) to (d) is added. It is an aqueous dispersion of a resin obtained by emulsion polymerization by a method described below.
[0007]
Examples of the ethylenically unsaturated carboxylic acid amide methylol derivative (a) used in the synthetic rubber latex of the present invention include N-methylol acrylamide, N-methylol methacrylamide and the like, and preferably N-methylol acrylamide. It is.
[0008]
Examples of the ethylenically unsaturated carboxylic acid amide (b) used in the synthetic rubber latex of the present invention include acrylamide, methacrylamide, N-butoxymethylacrylamide and the like, and preferably acrylamide.
[0009]
The mixing ratio of the methylol derivative (a) of the ethylenically unsaturated carboxylic acid amide and the ethylenically unsaturated carboxylic acid amide (b) is 3 ≧ (a) / (b) ≧ 0.15 (weight ratio). It is necessary. It is particularly preferable that 2 ≧ (a) / (b) ≧ 0.25 (weight ratio) in the above range. Here, when the value of (a) / (b) is less than 0.15 (weight ratio), the wet strength of the synthetic rubber latex decreases, which is not preferable. In addition, when the value of (a) / (b) exceeds 3 (weight ratio), the amount of formalin released increases to a level where the absorbance measured by the method described in JIS L1061 exceeds 0.05, and thus it is preferable. Absent.
[0010]
The mixing amount of the methylol derivative (a) of the ethylenically unsaturated carboxylic acid amide and the ethylenically unsaturated carboxylic acid amide (b) per total weight of the synthetic rubber latex is such that the total weight of (a) and (b) is unsaturated. It is necessary to make up 1 to 10% by weight of the total weight of the monomer mixture. Here, when the total weight of (a) and (b) is less than 1% by weight, the wet strength of the synthetic rubber latex decreases, which is not preferable. On the other hand, if it exceeds 10% by weight, the amount of aggregates (eg, gels) generated during the emulsion polymerization becomes extremely large, which is not preferable. Within the above range, it is particularly preferable that the content be 1 to 6% by weight based on the total weight of the unsaturated monomer mixture.
[0011]
Examples of the conjugated diene-based monomer (c) include 1,3-butadiene, isoprene, and 2-chloro-1,3-butadiene. Of these, 1,3-butadiene is preferable. The amount used is preferably in the range of 10 to 50% by weight based on the total weight of the monomers.
[0012]
When producing the synthetic rubber latex of the present invention, the ethylenically unsaturated carboxylic acid monomer (d) can be used if necessary. Examples thereof include itaconic acid, fumaric acid, maleic acid, methacrylic acid, half esters of acrylic acid and dicarboxylic acid, and the like, with preference given to acrylic acid, methacrylic acid and itaconic acid. One or more of these ethylenically unsaturated carboxylic acid monomers may be used, and the amount used is 0.5% of the total weight of the monomers because the mechanical strength of the latex sufficiently develops. % By weight or more, and preferably 10% by weight or less because the synthetic rubber latex is hardly thickened.
[0013]
When producing the synthetic rubber latex of the present invention, a copolymerizable vinyl compound (e) other than the above (a) to (d) can be used, if necessary. Examples of the vinyl compound (e) include styrene, α-methylstyrene, chlorostyrene, vinyltoluene, methacrylonitrile, acrylonitrile, methyl methacrylate, propyl methacrylate, hydroxyethyl methacrylate, and methacrylic acid-2- Ethylhexyl, lauryl methacrylate, methyl acrylate, ethyl acrylate, aminoethyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, butyl acrylate, 2-ethylhexyl acrylate, 2-ethylhexyl acrylate hydroxyethyl acrylate, Aminoethyl acrylate, dimethylaminoethyl acrylate, diethylaminoethyl acrylate and the like, most preferably styrene, The amount of preferably 30 to 80 wt% of the total weight of the monomers, in particular 40 to 70% by weight.
[0014]
The polymerization initiator used when the synthetic rubber latex of the present invention is obtained by emulsion polymerization is not particularly limited.For example, potassium persulfate, sodium persulfate, persulfate initiators such as ammonium persulfate, cumene hydro Organic peroxides such as peroxide, diisopropylbenzene hydroperoxide, and benzoyl peroxide; and hydrogen peroxide.
[0015]
In order to promote emulsion polymerization, sodium sulfite, sodium bisulfite, ferrous sulfate, glucose, formaldehyde, L-ascorbic acid, reducing agents such as sodium sulfoxylate, glycine, alanine, ammonium ethylenediaminetetraacetate and the like May be used in combination.
[0016]
The emulsifier used for the emulsion polymerization is a general anionic surfactant including a reactive surfactant, a nonionic surfactant and the like, and is not limited at all.
[0017]
The synthetic rubber latex of the present invention is based on the monomer composition described above, but in order to obtain an arbitrary molecular weight, a molecular weight modifier such as a chain transfer agent and a polymerization terminator or a polymerization rate modifier is appropriately used at the time of polymerization. can do. Further, the molecular weight may be controlled by interrupting the reaction by cooling. In addition, seed polymerization may be performed using an appropriate latex in order to control the particle diameter.
[0018]
As the chain transfer agent, for example, those used in ordinary polymerization can be used. For example, t-dodecyl mercaptan, n-todecyl mercaptan, octyl mercaptan, n-tetradecyl mercaptan, n-hexyl mercaptan Mercaptans, terpinolene, t-terpinene, α-methylstyrene dimer, ethyl xanthogen disulfide, diisopropylxanthogen sulfide, aminophenyl sulfide, tetraethylthiuram disulfide, etc., and one or more of these may be used. it can.
[0019]
Examples of the polymerization terminator include hydroquinone (phenol) -based, amine-based, sulfur-based, hydroxylamine sulfate, ammonia, caustic soda, caustic potash, and the like. Further, those having a polymerization terminating effect can be used. You may use two or more together. The amount used depends on the type of polymerization inhibitor and the reactivity ratio with the monomer.
[0020]
As a method for polymerizing the synthetic rubber latex of the present invention, for example, the monomers (a), (b), (c), (d), and (e) are added all at once and a one-stage emulsion polymerization reaction is carried out. (Hereinafter referred to as one-stage polymerization) or a polymer (I) obtained by emulsion polymerization of the monomers (a), (c), (d) and (e). ), A method of polymerizing a mixture of (c) and (e), if necessary, using (b) as an essential component to obtain a resin (II) (hereinafter referred to as two-stage polymerization), and the like. Is mentioned.
[0021]
Of the two methods, the two-stage polymerization is more preferable than the one-stage polymerization because the amide group is localized on the surface of the latex particles and the contribution to wet strength is increased.
[0022]
In the emulsion polymerization method, the monomer mixture is polymerized at 45 ° C to 90 ° C in the presence of an emulsifier, a polymerization initiator, a polymerization accelerator, a chain transfer agent, and a basic compound. At this time, the conditions are the same for the one-stage emulsion polymerization reaction and the two-stage polymerization.
[0023]
Emulsion polymerization may be carried out by various methods using the above-mentioned polymerization emulsifier, chain transfer agent, polymerization initiator, polymerization inhibitor and the like, as well as various electrolytes, pH adjusters and the like, if necessary.
[0024]
The synthetic rubber latex of the present invention preferably has a non-volatile content of 30 to 70% by weight from the viewpoint of handling, but can be used by diluting it with water, a water-soluble solvent or the like, if necessary.
[0025]
Further, to the synthetic rubber latex of the present invention, formalin catcher such as urea, ethylene urea, dicyandiamide, hydroxylamine hydrochloride can be added at the time of polymerization or after the polymerization, or in an appropriate amount. In addition, the following compounding materials may be added according to the purpose of use.
[0026]
Additives that may be added to the synthetic rubber latex of the present invention include, for example, water absorbing agents, coloring agents such as inorganic pigments and organic pigments, chelating agents, dispersants, antioxidants, ultraviolet absorbers, surfactants, and compression agents. Recovery agents, defoamers, bactericides, preservatives, wetting agents, crosslinking agents other than melamines, vulcanizing agents such as zinc oxide, sulfur, vulcanization accelerators, tack inhibitors, foaming agents, foam stabilizers, Examples include penetrants, water / oil repellents / anti-blocking agents, flame retardants, fillers, thickeners, and the like. The selection, amount and order of addition of the formalin catcher or the additive are preferably in the range of 0.0001 parts by weight to 10 parts by weight with respect to 100 parts by weight of the SBR latex. It may be appropriately determined in consideration of properties, stability, processing suitability, application amount, and the like.
[0027]
【Example】
Hereinafter, the present invention will be described with reference to Examples, but parts and percentages in Examples and Tables are by weight unless otherwise specified.
Examples 1 to 6
130 parts of distilled water, 1.5 parts of a polymerization emulsifier, 0.2 parts of t-dodecyl mercaptan, and butadiene, styrene, N-methylolacrylamide, acrylamide and a monomer of acrylic acid were charged into an autoclave as shown in Table 1, After the temperature was raised to 60 ° C., 0.3 part of ammonium persulfate was charged and reacted for 10 hours. After completion of the reaction, the pH was adjusted to 8.0 or more with ammonia, stripping was performed, 2 parts of urea was added, and the pH was adjusted to 7.5 to 8.0 with ammonia to obtain synthetic rubber latex 1 to 6. This latex was diluted to 5% and no. 2 After impregnating the filter paper (manufactured by Toyo Roshi Kaisha) with a resin adhesion amount of 17%, the adhesion amount was adjusted with a mangle roll. The obtained impregnated filter paper was dried at 140 ° C. for 10 minutes and cut into a test piece having a width of 1.5 cm and a length of 15 cm, which was used as a test piece for measuring tensile strength in normal and wet conditions. The wet tensile strength was measured after immersion in water at 25 ° C. for 1 hour. Further, 2.5 g of the remaining specimen was precisely weighed, and the amount of free formalin (absorbance) was measured according to JISL 1041 (Method A: acetylacetone method). However, the absorbance of 0.05 or less is the detection limit.
[0028]
Examples 7 to 12
130 parts of distilled water, 1.5 parts of polymerization emulsifier, 0.2 parts of t-dodecyl mercaptan and monomers of butadiene, styrene, N-methylolacrylamide, acrylamide, acrylic acid and itaconic acid were placed in an autoclave as shown in Table 2. After heating to 60 ° C., 0.3 part of ammonium persulfate was charged and reacted for 8 to 10 hours. After the reaction was completed, the pH was adjusted to 8.0 or more with ammonia, stripping was performed, and 2 parts of urea were added. Then, the pH was adjusted to 7.5 to 8.0 with ammonia to obtain synthetic rubber latexes 7 to 12. This latex was diluted to 5% and no. 2 After impregnating the filter paper (manufactured by Toyo Roshi Kaisha) with a resin adhesion amount of 17%, the adhesion amount was adjusted with a mangle roll. The obtained impregnated filter paper was dried at 140 ° C. for 10 minutes and cut into a test piece having a width of 1.5 cm and a length of 15 cm, which was used as a test piece for measuring tensile strength in normal and wet conditions. The wet tensile strength was measured after immersion in water at 25 ° C. for 1 hour. Further, 2.5 g of the remaining test piece was precisely weighed, and the amount of free formalin (absorbance) was measured according to JIS L 1041 (Method A: acetylacetone method). However, the absorbance of 0.05 or less is the detection limit.
[0029]
Examples 13 to 18
130 parts of distilled water, 1.5 parts of a polymerization emulsifier, 0.2 parts of t-dodecyl mercaptan, and butadiene, styrene, N-methylolacrylamide and acrylic acid monomers were charged into an autoclave as shown in Table 3, and then heated at 60 ° C. After the temperature was raised, 0.3 part of ammonium persulfate was charged and the reaction was carried out for 8 to 10 hours. As shown in Table 3, acrylamide, styrene, butadiene and 0.2 part of ammonium persulfate were added to the obtained latex, and the mixture was further reacted at 65 ° C. for 6 to 8 hours. After completion of the reaction, the pH was adjusted to 8.0 or more with ammonia, stripping was performed, 2 parts of urea was added, and the pH was adjusted to 7.5 to 8.0 with ammonia to obtain synthetic rubber latexes 13 to 18. This latex was diluted to 5% and no. 2 After impregnating the filter paper (manufactured by Toyo Roshi Kaisha) with a resin adhesion amount of 17%, the adhesion amount was adjusted with a mangle roll. The obtained impregnated filter paper was dried at 140 ° C. for 10 minutes and cut into a test piece having a width of 1.5 cm and a length of 15 cm, which was used as a test piece for measuring tensile strength in normal and wet conditions. The wet tensile strength was measured after immersion in water at 25 ° C. for 1 hour. Further, 2.5 g of the remaining test piece was precisely weighed, and the amount of free formalin (absorbance) was measured according to JIS L 1041 (Method A: acetylacetone method). However, the absorbance of 0.05 or less is the detection limit.
[0030]
Comparative Examples 1 to 5
130 parts of distilled water, 1.5 parts of a polymerization emulsifier, 0.2 parts of t-dodecyl mercaptan and butadiene, styrene, N-methylolacrylamide, acrylamide and a monomer of acrylic acid were charged into an autoclave as shown in Table 4, After the temperature was raised to 60 ° C., 0.3 part of ammonium persulfate was charged and reacted for 10 hours. After completion of the reaction, the pH was adjusted to 8.0 or more with ammonia, stripping was performed, 2 parts of urea was added, and the pH was adjusted to 7.5 to 8.0 with ammonia to obtain synthetic rubber latexes 19 to 24. This latex was diluted to 5% and no. 2 After impregnating the filter paper (manufactured by Toyo Roshi Kaisha) with a resin adhesion amount of 17%, the adhesion amount was adjusted with a mangle roll. The obtained impregnated filter paper was dried at 140 ° C. for 10 minutes and cut into a test piece having a width of 1.5 cm and a length of 15 cm, which was used as a test piece for measuring tensile strength in normal and wet conditions. The wet tensile strength was measured after immersion in water at 25 ° C. for 1 hour. Further, 2.5 g of the remaining test piece was precisely weighed, and the amount of free formalin (absorbance) was measured according to JIS L 1041 (Method A: acetylacetone method). However, the absorbance of 0.05 or less is the detection limit.
[0031]
Comparative Examples 6 to 11
130 parts of distilled water, 1.5 parts of a polymerization emulsifier, 0.2 parts of t-dodecyl mercaptan, and butadiene, styrene, N-methylolacrylamide and acrylic acid monomers were charged into an autoclave as shown in Table 5, and heated at 60 ° C. After the temperature was raised, 0.3 part of ammonium persulfate was charged and the reaction was carried out for 8 to 10 hours. As shown in Table 5, acrylamide, styrene, butadiene and 0.2 part of ammonium persulfate were added to the obtained latex, and the mixture was further reacted at 65 ° C. for 6 to 8 hours. After completion of the reaction, the pH was adjusted to 8.0 or more with ammonia, stripping was performed, 2 parts of urea was added, and the pH was adjusted to 7.5 to 8.0 with ammonia to obtain synthetic rubber latex 25 to 30. This latex was diluted to 5% and no. 2 After impregnating the filter paper (manufactured by Toyo Roshi Kaisha) with a resin adhesion amount of 17%, the adhesion amount was adjusted with a mangle roll. The obtained impregnated filter paper was dried at 140 ° C. for 10 minutes and cut into a test piece having a width of 1.5 cm and a length of 15 cm, which was used as a test piece for measuring tensile strength in normal and wet conditions. The wet tensile strength was measured after immersion in water at 25 ° C. for 1 hour. Further, 2.5 g of the remaining test piece was precisely weighed, and the amount of free formalin (absorbance) was measured according to JIS L 1041 (Method A: acetylacetone method). However, the absorbance less than 0.05 is the detection limit.
[0032]
The impregnated paper in the table was judged as acceptable when the normal strength of the impregnated paper was 17 Mpa or more and the wet strength was 8 Mpa or more (○). A paper having a normal strength of less than 17 Mpa or a wet strength of less than 8 Mpa was rejected (x). In addition, the determination of the formalin release amount was judged as acceptable (○) when the amount of free formalin (absorbance) was 0.05 or less, and as unacceptable (×) when it exceeded 0.05.
[0033]
[Table 1]

[0034]
[Table 2]

[0035]
[Table 3]

[0036]
[Table 4]

[0037]
[Table 5]

[0038]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the synthetic rubber latex used for the fiber binder and pulp nonwoven fabric use which the wet tensile strength of pulp fiber, synthetic fiber, etc. is remarkably improved and the free formalin content was reduced can be provided.

Claims

It is obtained by polymerizing an unsaturated monomer mixture containing a methylol derivative of an ethylenically unsaturated carboxylic acid amide (a), an ethylenically unsaturated carboxylic acid amide (b) and an aliphatic diene monomer (c). A synthetic rubber latex, wherein the compounding ratio of the ethylenically unsaturated carboxylic acid amide methylol derivative (a) to the ethylenically unsaturated carboxylic acid amide (b) is 3 ≧ (a) / (b) ≧ 0.15 ( (Weight ratio) and the total weight of (a) and (b) is 1 to 10% by weight of the total weight of the unsaturated monomer mixture.

The synthetic rubber latex according to claim 1, wherein the content of the aliphatic diene monomer (c) is 10 to 50% by weight based on the total weight of the unsaturated monomer mixture.

The unsaturated monomer is obtained by adding 0.5 to 10% by weight of the ethylenically unsaturated carboxylic acid monomer (d) to the total weight of the unsaturated monomer mixture and polymerizing the monomer. 3. The synthetic rubber latex according to 1 or 2.

Further, as the unsaturated monomer, a vinyl compound (e) other than the above (a) to (d) is obtained by adding 30 to 80% by weight of the total weight of the unsaturated monomer mixture and polymerizing. 3. The synthetic rubber latex according to 3.

After the synthetic rubber latex emulsion-polymerizes the unsaturated monomer other than the above (b) to obtain a polymer (I), a monomer containing (b) is added in the presence of the polymer (I). The synthetic rubber latex according to any one of claims 1 to 4, wherein the synthetic rubber latex is a polymer (II) obtained by emulsion polymerization of a body mixture.