JP2004203913A - Preparation process and use of aqueous resin dispersion - Google Patents

Preparation process and use of aqueous resin dispersion Download PDF

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Publication number
JP2004203913A
JP2004203913A JP2002371259A JP2002371259A JP2004203913A JP 2004203913 A JP2004203913 A JP 2004203913A JP 2002371259 A JP2002371259 A JP 2002371259A JP 2002371259 A JP2002371259 A JP 2002371259A JP 2004203913 A JP2004203913 A JP 2004203913A
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Japan
Prior art keywords
resin
viscosity
dispersion
weight
water
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JP2002371259A
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Japanese (ja)
Inventor
Yasunori Yamashita
泰則 山下
Yuki Kaneko
由紀 金子
Tomoatsu Kitamura
友厚 北村
Ritsuhin O
立彬 王
Morikazu Kuwabara
盛一 桑原
Yutaka Ono
豊 大野
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Toyo Ink Mfg Co Ltd
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Toyo Ink Mfg Co Ltd
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Priority to JP2002371259A priority Critical patent/JP2004203913A/en
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating material which is excellent in storage stability and applicability in roll coating and gives a coating film excellent in physical properties. <P>SOLUTION: A partially reacted resin solution (E) is prepared by partially reacting 100 pts.wt. acrylic resin (A) containing 30-70 wt.% monobasic acid monomer and having a weight average mol.wt. of 3,000-30,000, 100-1,000 pts.wt. aromatic epoxy resin (B) having a number average mol.wt. of 1,400 or higher, and 10-100 pts.wt. amine (C) in the presence of an organic solvent (D) in an amount of 60 wt.% or lower based on the sum of the acrylic resin (A) and the aromatic epoxy resin (B). The objective aqueous resin dispersion is prepared through the following steps: step 1 wherein the partially reacted resin solution (E) is agitated at a shear rate of 200/sec or lower while water is being added thereto, giving a predispersion (F) of an O/W type, and step 2 wherein the predispersion (F) is agitated at a shear rate of 400/sec or higher to finely disperse the resin particles predispersed therein to reduce the average particle size to 1 μm or lower. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【0001】
【発明の属する技術分野】
本発明は水性樹脂分散体の製造方法である。また、この製造方法で得られる水性分散体と、優れた貯蔵安定性、ロールコート性、塗膜物性を有する塗料に関する。
【0002】
【従来の技術】
水性樹脂分散体は粒子径を小さくすることによって貯蔵安定性が増すため、さまざまな微細化の試みがなされている。微細な水性樹脂分散体を得るためには、転相点近傍で高剪断力が必要なこと、剪断負荷が一定時間以上必要であることは公知である。そして、転相点を離れると分散は不可能になると考えられてきた。
【0003】
代表的理論としては、たとえば図1に示すように、(分散粒子内部の粘度)と(分散粒子の外側の粘度)の粘度比Pが5以下でなければ分散不可能と考えられてきた(例えば、非特許文献1参照。)。以下、(分散粒子内部の粘度)/(分散粒子の外側の粘度)を粘度比Pと略称する。
【0004】
図1において、
(臨界Weber数)=(分裂を起こす最小の剪断速度)×(静止時の液滴径)×(分散粒子の外側の粘度)/(液滴の界面張力)
で表される。
【0005】
本発明における粘度は、粘性についての詳細な記述が必要な場合以外は便宜上B型粘度計#4ローター0.6rpmの測定値を示した。粘度が非常に高い又は低いために0.6rpmの値が求まらない場合は別の回転数で求めて補外した。
【0006】
(分散粒子の外側の粘度)を単に水の粘度1mPa・sとすれば、5mPa・s以上の樹脂溶液は微細化できないことになる。したがって、粘度比5以下とは極めて大きなハードルであると考えられ、転相点を過ぎた水性樹脂分散体については再分散による微細化は不可能であると考えられてきた。
【0007】
そのため、従来においては転相点一点に強力な剪断力をかける事にこだわったため、処理液が高粘度になると動力が莫大に必要になるだけでなく発熱が制御できなくなるという問題点を有していた。特に、高温に弱い水性樹脂分散体においては深刻な問題であった。
【0008】
また、環境保護の観点から有機溶剤の使用量を少なくする場合、高粘度系において微細化する必要が生じる。しかし、これは莫大な動力を必要とするとともに激しい発熱のため非常に困難であった。
【0009】
従来においては、カルボキシル基含有アクリル樹脂成分、エポキシ樹脂成分及びエポキシ樹脂用硬化剤樹脂成分を単独又は組み合わせで含む有機溶剤溶液と、アンモニア又はアミン類の水溶液とともにインラインミキサーを用いて先ずW/O型分散体を得、続いて第二段のインラインミキサーで水をさらに混合しO/W型水性樹脂分散体を得る方法がある(例えば、特許文献1参照。)。
【0010】
この方法では多量の有機溶剤を使用し、生成した水性樹脂分散体を脱溶剤する工程を必要とする。第二段のインラインミキサーによる工程はW/OからO/Wへの転相を含み、この分散過程において最も大きな粘度になる。微細な粒子を得るためには大きな剪断力を必要とするが、有機溶剤を少なくすると系の粘度が上昇してインラインミキサーで分散できず、微細な粒子を得ることは出来なかった。
【0011】
また、同一容器内に混合混錬部と高速剪断機構部を有する分散機に、樹脂溶液と水とを一定の割合で一気に導入する方法もある(例えば、特許文献2参照。)。この方法では分散機内で一気に転相点を越えることになり、分散処理中に最大粘度を通過し、大きな負荷が掛かるためにあまり高粘度には適用できなかった。
【0012】
予備乳化混合液を100〜10000kg/cmの圧力で平面部に衝突させることによって微細化する方法も開示されている(例えば、特許文献3参照。)。対象物を細管通過後衝突させるタイプの微細化分散機はこの他にも提案されているが、細管を通過する過程で圧力損失が生じることと極めて短時間の仕事であるために、高粘度品では温度を制御できず激しい発熱があり、熱に弱い水分散体には使用できない。また短時間の作用であるために樹脂溶液の種類によっては微細化する前に復元してしまい効果が出ない場合がある。
【0013】
また、微小液滴形成装置等の分散機もある(例えば、特許文献4参照。)が、高粘度品には対応できなかった。
【0014】
一方、転相点近傍又は最大粘度において高剪断をかける場合は、極めて強力な分散機を必要とするだけでなく激しい発熱が避けられない(例えば、特許文献5参照。)。
【0015】
【非特許文献1】
化学工学論文集第2巻第3号(1976)、244頁、図3
【特許文献1】
特開平1−292068号公報
【特許文献2】
特開平4−220433号公報
【特許文献3】
特開平5−98192号公報
【特許文献4】
特開平8−196887号公報
【特許文献5】
特開平2−261824号公報
【0016】
【発明が解決しようとする課題】
以上のとおり、本発明は高粘度樹脂溶液の微細化分散を目的とする。
【0017】
【課題を解決するための手段】
本発明者らは鋭意検討を重ねた結果、いくつかの解決策と発明を得た。
発明者らは上記の理論と実験を検証した結果、上記の議論は水と流動パラフィンのように、粒子の境界面のはっきりした液滴について適合する理論であって、水性樹脂分散体の場合は異なることを見出した。
まず、分散粒子に外部から働きかける力の要素になる“分散粒子の外側の粘度”としては分散液の粘度(VF)を採るのが適切と考えた。
【0018】
更に、“分散粒子内部の粘度”そのものは▲1▼粒子内の溶剤組成が粒子外と出入りし平衡状態になること、▲2▼平衡定数が液温その他さまざまな条件で変化しうること、▲3▼平衡状態にならず、遷移中の非定常状態の場合もあること、▲4▼粒子が小さいために直接測定が困難であること、▲5▼測定時に遠心分離等の手段で平衡状態を壊してしまうこと、等により測定が困難である。しかし、およそ水添加前の樹脂溶液粘度の近傍であると考えられることから、本発明では“分散粒子内部の粘度”として水添加前の部分反応樹脂溶液粘度(VE)で代用することとした。従って、本発明では“粘度比”Pを(VE)/(VF)とした。
【0019】
発明者らは、水性樹脂分散体の境界面は連続的に変化する層と考え、必ずしも粒子の内部粘度と外部粘度の比=粘度比Pが5以下でなくても微細化分散が可能ではないかと考え実験を重ねたところ、粘度比が500以下であれば微細化が可能であることを見出し、本発明を完成することができた。
【0020】
すなわち、本発明の第1の発明は、一塩基酸モノマー30〜70重量%を含む重量平均分子量3000〜30000のアクリル樹脂(A)100重量部と、数平均分子量1400以上の芳香族系エポキシ樹脂(B)100〜1000重量部と、アミン類(C)10〜100重量部とを、アクリル樹脂(A)と芳香族系エポキシ樹脂(B)の合計に対して60重量%以下の有機溶剤(D)の存在下で部分反応させた部分反応樹脂溶液(E)を得た後、以下の工程により得られる水性樹脂分散体の製造方法である。
工程1:部分反応樹脂溶液(E)水を添加しながら剪断速度200/秒以下で攪拌し転相させてO/W型の予備分散体(F)を得た後に、
工程2:予備分散体(F)を剪断速度400/秒以上で攪拌し、樹脂分散粒子を平均粒子径1μm以下に微細化分散する。
【0021】
第2の発明は、転相前の最大粘度(Vmax)が20Pa・s以上、かつ予備分散体(F)の粘度(VF)が100Pa・s以下であり、かつ、同一温度における部分反応樹脂溶液(E)の粘度(VE)と予備分散体(F)の粘度(VF)との粘度比P=(VE)/(VF)が、10〜500である第1の発明に記載の水性樹脂分散体の製造方法である。
【0022】
第3の発明は、有機溶剤(D)の70重量%以上が水と自由に相互溶解する有機溶剤である第1又は第2の発明に記載の水性樹脂分散体の製造方法である。
第4の発明は、第1〜第3の発明いずれかに記載の水性樹脂分散体の製造方法で得られる水性樹脂分散体である。
第5の発明は、第4の発明に記載の水性樹脂分散体を用いて得られる塗料である。
【0023】
本発明で用いられるアクリル樹脂(A)とは、一塩基酸モノマーと共重合性モノマーとを、アゾビスイソブチロニトリルや過酸化ベンゾイル等のラジカル発生剤を触媒として重合したものである。
【0024】
一塩基酸モノマーとは、アクリル酸やメタクリル酸等のカルボン酸を含むモノマーである。アクリル樹脂(A)における一塩基酸モノマーの含有量が30重量%未満では、部分反応樹脂溶液(E)を水性化することが困難になる。また、70重量%を超えるとではアクリル樹脂(A)がアミン類(C)と塩を形成し、水等の極性の強い溶媒にしか溶解しなくなるが、水はアクリル樹脂(A)とエポキシ樹脂(B)との反応を抑制し、使用に制限が生じるために好ましくない。
【0025】
共重合性アクリルモノマーとしては、アクリル酸メチル、アクリル酸エチル、アクリル酸ブチル、アクリル酸2−エチルヘキシル等のアクリル酸エステル、メタクリル酸メチル等のメタクリル酸エステル、スチレン、アルファメチルスチレン等のフェニル核を持つモノマー、アクリル酸2−ヒドロキシエチル、メタクリル酸2−ヒドロキシエチル、N−メチロール(メタ)アクリルアミド等の水酸基含有のモノマー、N−メトキシメチル(メタ)アクリルアミド等のN−置換アルコキシル基含有のモノマー、その他アクリロニトリルやグリシジル基含有モノマー等が挙げられる。これら1種、又は2種以上を選択して用いることができる。
【0026】
本発明における樹脂の分子量とは、基本的にGPCで測定したスチレン換算の重量平均分子量に基づいたものである。本発明で扱う高分子の領域では数平均分子量は低分子領域の僅かなベースラインの凹凸で数値に誤差を生じやすいためである。数平均分子量は場合により参考値を示す。
【0027】
スチレン換算を用いるのは化合物の極性の違いによる誤差等の懸念はあるものの、業界ですでに広く用いられ、共通の認識が得られていると考えられるためである。分子量標準のスチレンも市販されているので、特にGPC測定条件を述べる必要がない状況になっていると判断できる。
【0028】
上記の一塩基酸モノマーと共重合性モノマーを用いて重合する際、重合開始剤の量と反応温度を選択して、適切な重量平均分子量を有するアクリル樹脂を得ることができる。本発明で用いられる重量平均分子量3000〜30000のアクリル樹脂(A)は、70〜150℃の温度で共重合させることにより得られる。
【0029】
重量平均分子量が3000未満では加工性等の重要かつ高度な水準の塗膜物性を保持できない。30000を超えるとでは水性塗料にした場合、非ニュートン流動性が強くなり、ロールコート適性が悪くなるので用いることができない。
【0030】
本発明で用いられる、数平均分子量1400以上の芳香族系エポキシ樹脂(B)は、ビスフェノールAやビスフェノールF等の二官能フェノールとエピクロルヒドリンをアルカリ触媒下で反応させ、高分子量化することによって得ることができる。数平均分子量1400未満では加工性等の高度な塗膜物性を保持できないので用いることができない。また、分子量40000を超えるものはあまり用いられない。特に塗料用途においては、分子量3000〜30000の範囲のものが好ましい。
【0031】
末端にグリシジル基を持つ樹脂はエポキシ樹脂と呼ばれ、一般に市販されている。末端のグリシジル基にフェノール性水酸基やアルコールや脂肪酸等で変性してグリシジル基の量を調節できる。フェノール類を反応させ、両末端が実質的に完全にフェノール性水酸基になったものはフェノキシ樹脂と呼ばれるが、フェノキシ樹脂の名称の製品群の中にも意識的にグリシジル基を一部残しているものもあり、エポキシ樹脂との境界は必ずしも明解ではない。したがって、本発明ではそれらを全部含めて芳香族系エポキシ樹脂(B)とする。いずれも市販されている。
【0032】
代表的な例をいくつか示すと、ジャパンエポキシレジン(株)の製品としてはビスフェノールAを原料としたエピコート1009、エピコート1010や、ビスフェノールFを原料としたエピコート4010P等がある、また、フェノキシ樹脂ではエピコート4250やエピコート1256等がある。
【0033】
東都化成(株)の製品としてはビスフェノールAを原料としたエポトートYD−019、エポトートYD−7019、エポトートYD−7020等がある。また、フェノキシ樹脂ではフェノトートYP−50やフェノトートYP−70等がある。
【0034】
本発明で用いられるアミン類(C)としては、アンモニア、トリエチルアミン等のアルキルアミン類、2−ジメチルアミノエタノール等のアルコールアミン類やエチレンジアミン等の多価アミンやモルホリン、ピリジン等が挙げられる。
【0035】
本発明で用いられる有機溶剤(D)としては、ロールコートのように、ニュートニアンな流動性を好む場合は、樹脂、水共に良好に溶解するものを主成分に選択する。好ましくは有機溶剤(D)の70重量%以上を、水と自由に相互溶解する有機溶剤から選択する。
【0036】
本発明の水性分散体を塗料として用いる場合は、塗料の乾燥・焼付け条件によって溶剤の沸点が選択できる。その他水性塗料の泡立ち・泡消え性や濡れ性についても表面張力等溶剤の諸性質により選択できる。
【0037】
具体的には以下のような溶剤の中から数種類を選択する。
水と自由に相互溶解する有機溶剤を挙げるとエタノール、n−プロパノール、イソプロパノール等のアルキルアルコール類、エチレングリコールモノエチルエーテル、エチレングリコールモノプロピルエーテル、エチレングリコールモノブチルエーテル、ジエチレングリコールモノメチルエーテル、ジエチレングリコールモノプロピルエーテル、ジエチレングリコールモノブチルエーテル、プロピレングリコールモノメチルエーテル、プロピレングリコールモノn−プロピルエーテル等のエーテルアルコール類、ダイアセトンアルコール等のケトンアルコール類等がある。
【0038】
その他の溶剤として、n−ブタノール、イソブタノール、ヘキシルアルコール、ノニルアルコール等のアルキルアルコール類、エチレングリコールモノヘキシルエーテルのようなアルキル基の大きなエーテルアルコール類、エチレングリコールモノメチルエーテルアセテート等のエーテルエステル類、酢酸エチル等のエステル類、シクロヘキサノン等のケトン類等が挙げられる。
【0039】
アクリル樹脂(A)とエポキシ樹脂(B)とを、有機溶剤(D)中でアミン類(C)を触媒として反応させて部分反応樹脂溶液(E)が得られる。
有機溶剤(D)はアクリル樹脂(A)の合成にも必要である。本発明を限定するものではないが典型的な合成方法の例として、まず、有機溶剤(D)中でアクリル樹脂(A)を合成し、その中にエポキシ樹脂(B)を添加して溶解し、その後に適切な反応条件を設定して、アミン類(C)を添加し、反応を開始すれば良い。この反応は進むにつれて酸価が低下し、エポキシ当量が上昇し、粘度が上昇するので、その程度を判定して終点を決めることができる。
【0040】
反応が進みすぎると粘度が高くなりすぎ、さらに反応が進みすぎると一般にゲル化するおそれがあるので好ましくない。粘性や塗膜物性も反応程度によって変化するので、適切な範囲で反応の終点としなければならない。酸価を有する未反応のアクリル樹脂成分は水相に溶解するので、水性樹脂分散体を遠心分離し、水相の不揮発分を定量し、樹脂全体との比率を計算することによって、未反応アクリル樹脂/全アクリル樹脂の比率を定量できるので、反応程度を確認できる。
【0041】
本発明の水性樹脂分散体の製造方法における各成分の量は、アクリル樹脂(A)100重量部に対し、エポキシ樹脂(B)100〜1000重量部、アミン類(C)10〜100重量部である。また、有機溶剤(D)は、(A)と(B)の合計に対して60重量%以下である。特に10〜60重量%が好ましい。
【0042】
上記において、アクリル樹脂(A)とエポキシ樹脂(B)の比率は塗料の粘性と塗膜物性のバランスを考慮の上選択されている。アクリル樹脂(A)100重量部に対するエポキシ樹脂(B)の配合量は、加工性の観点から100重量部以上、非ニュートニアン流動性が弱くロールコート適性が良好の観点から1000重量部以下である。特にアクリル樹脂(A)100重量部に対してエポキシ樹脂(B)100〜500重量部が好ましい。
【0043】
アクリル樹脂(A)とエポキシ樹脂類(B)の反応の終点が確認でき部分反応樹脂溶液(E)が得られた後、以下に示す工程1、工程2の手順を行い本発明の水性樹脂分散体が得られる。
工程1は、部分反応樹脂溶液(E)に剪断速度20/秒以上で攪拌しながら水を添加・分散し、最大粘度を経過して転相点を迎え、O/W型の予備分散体(F)を得る工程である。特に剪断速度20〜200/秒の範囲が好ましい。転相点は粘度低下やトルク低下、または電気伝導度や目視で分かる。剪断速度20/秒未満の条件では、実質的に攪拌混合できなくなるおそれがあり熱伝導が不良となるので用いられない。
【0044】
剪断速度は一般に速度勾配とも呼ばれ、(速度差)/(距離)で定義されている。しかしながら、この値が注目している系全体において一様とは言えないために、どのような値を代表値として採用するかは必ずしも明確ではなく、複雑な計算方法も多い。本発明においては簡単に計算できる方法を用い、回転の際の攪拌翼やローターのピンの周速値を容器壁面とのクリアランスで除した値を用いる。
【0045】
すなわち、本発明において(剪断速度〔/秒〕)=(回転体の周速〔m/秒〕)/(回転体と容器壁面とのクリアランス〔m〕)とする。
転相点は電気伝導度が急激に大きくなる等系の性質が大きく変化することで知ることができる。
【0046】
工程1における転相処理の際、水を段階的に添加していくと、樹脂の種類・官能基の種類と量・温度によって異なるが、粘度は一般に最大値を経て転相点に到る。水を添加するにつれて▲1▼系の温度が低下するために粘度が上昇するためと、▲2▼樹脂溶液相と水相がお互いの連続相に邪魔され自由に活動できなくなるためであると考えられる。
【0047】
工程1における分散体の最大粘度Vmaxが20Pa・s未満の場合は特に本発明の方法を用いる必要はなく、従来から一般に使用されている分散機を用いて、一段階で転相させ微細化分散することができる。
【0048】
一方、分散体の最大粘度Vmaxが20Pa・s以上(温度限定なし)になると、従来の一段階で転相して微細な分散体を得る方法は困難になる。高粘度型の力の強い攪拌機を用いて低剪断速度で分散する場合、1μm以下の粒子径の微細粒子を得ることはできない。一方、高剪断速度で分散する場合は、例えばホモジナイザーやクレアミックスのような、狭い領域に液を吸い込み回転子と壁の剪断により微細化する型の分散機は吸い込みが困難になり使用できなくなる。また、デゾルバーやディスパーと呼ばれている円盤状高速攪拌型分散機は、攪拌円盤および攪拌軸に液が巻きつく現象が現れ、やはり分散が困難になる。
【0049】
本発明を用いれば、分散体の最大粘度Vmaxが20Pa・s以上(温度限定なし)であっても、まず予備分散し最大粘度を越えて転相させること(工程1)ができる。その後、再度高剪断下で微細化分散を行い、1μm以下の粒子径の微細粒子を得ることができる(工程2)。
【0050】
しかしながら、分散体の最大粘度Vmaxがさらに大きくなり、工程2の微細化分散においても予備分散体(F)の粘度(VF)が100Pa・sを越える場合には、もはや本発明の方法を用いても、通常の分散機では微細化分散が不可能となる。
すなわち、工程1において、転相前の最大粘度(Vmax)が20Pa・s以上、かつ予備分散体(F)の粘度(VF)が100Pa・s以下であり、かつ、同一温度における部分反応樹脂溶液(E)の粘度(VE)と予備分散体(F)の粘度(VF)との粘度比P=(VE)/(VF)が、10〜500であることが特に好ましい。
【0051】
また、特に有機溶剤(D)の70重量%以上が水と自由に相互溶解する有機溶剤からなる場合、部分反応樹脂溶液(E)に水を添加中、部分反応樹脂溶液(E)相から有機溶剤が水相に抜け出す現象が起こり樹脂溶液相の粘度が上昇する。そのため、従来では水性樹脂分散体をつくることが全く困難であったが、本発明の方法によりはじめて可能となった。
【0052】
工程2は、予備分散体(F)に剪断速度400/秒以上の攪拌で高剪断力をかけ、平均粒子径1μm以下になるまで微細化分散し、冷却、水希釈してエマルジョンの粒径を整える工程である。特に剪断速度400〜10000/秒の範囲が好ましい。この工程により、本発明の水性樹脂分散体が得られる。
【0053】
上記に示したように、本発明は二段の分散工程を含む多段分散法であり、工程2が特に重要である。
【0054】
工程2において、予備分散体(F)に高剪断力をかけるために用いられる微細化分散装置Xとして、剪断速度400/秒以上にできる構造と動力を持ち、かつ、滞留時間を30秒以上取っても処理中の液の温度を30℃以上100℃未満に保つことができる加熱・冷却能力を有する分散装置を用いることが望ましい。圧力条件にも左右されるが、泡が生じると剪断力がかかりにくくなるため水が沸騰しない温度で行うことが好ましい。
【0055】
微細化分散装置Xとしては、デゾルバーやディスパーと呼ばれている円盤型分散機が挙げられる。また、円盤型分散機と低速攪拌機とを併用して一つの反応釜で全工程を行うことができる特開平7−173294号公報に記載の複合乳化装置や特開平8−117578号公報に記載の分散機等が挙げられる。
【0056】
具体的には、(株)ユーロテック製CAVITRONホモジナイザーを挙げられる。例えば工程1でこの機械を用いると、分散機の能力を超えるため分散不良になる。そこで工程1では、分散力は強いが周速が遅く剪断速度は小さい高粘度用の攪拌機を用いて剪断速度200/秒以下で粗分散し、最高粘度域を経て転相点を通過させて予備分散体(F)を得る。
【0057】
その後の工程2における分散体溶液の粘度は、工程1における最高粘度に比べて1/2〜1/10程度まで低下している。従って、工程2の微細化分散工程でこの機械を使用すれば、剪断速度400/秒以上の攪拌が可能であり、分散体溶液全体に均一に剪断を与えることができ微細化分散することができる。
【0058】
微細化分散を行う時には、目的に応じて適切な水の量と分散温度を選択する。添加する水の量が少なすぎると、樹脂分散体の粘度が高いために、特殊で強力な分散機が必要になる。また、発熱が大きくなる等の不都合が生じる。一方、添加する水の量が多すぎると粘度比Pは500以上になり、微細化が不可能になる。したがって、部分反応樹脂溶液(E)の粘度(VE)と予備分散体(F)の粘度(VF)との粘度比P=(VE)/(VF)が4〜500、好ましくは10〜100となるように水の量を調節する。
このとき、予備分散体(F)の粘度は添加する水の量と温度と剪断速度で変化するので、同一温度・同一剪断速度で測定する。
【0059】
本発明の水性樹脂分散体の製造方法においては、さらに目的に応じて、工程のどこでも適切な条件で有機溶剤、中和剤、界面活性剤、消泡剤、滑り剤、硬化剤、防錆剤、顔料、充填剤等を添加・配合することができる。
【0060】
本発明の製造方法で得られた水性樹脂分散体の用途としては、塗料が挙げられる。この場合、得られた水性樹脂分散体に水を添加し必要に応じて消泡剤・湿潤剤・滑り剤・硬化剤等の添加剤や粘度調節・固形分量調節を行う。得られた塗料はブリキ板、クロムメッキ鋼板、ティンフリースチール、アルミ板等の金属板に塗装することが出来る。特に缶内面用塗料として有効である。
塗装方法としてはロールコーター、スプレー、電着塗装等が可能であるが、ロールコーターでの塗装性能に優れている。
【0061】
【実施例】
以下、本発明を実施例により説明する。なお、例中「部」、「%」はそれぞれ「重量部」、「重量%」を示す。粘度は基本的にB型粘度計#4ローター、0.6rpmの安定した値を求めた。0.6rpmで値が求められない場合は0.3rpm又は1.5〜30rpmの値から補外して求めた。分子量はGPCで測定し、スチレン換算の重量平均分子量を基本にした。分子量分布が必要な場合は適宜、数平均分子量や組成を示した。
【0062】
〔アクリル樹脂溶液(a)の製造〕

Figure 2004203913
【0063】
攪拌機、窒素導入管、水冷式冷却管、温度センサー、滴下タンクを設置した200L反応釜に1)〜6)を仕込み、攪拌しながら130℃まで加熱した。滴下タンクに混合溶解した7)〜12)を入れ、反応釜内温130℃を保持しながら、2時間で滴下した。
滴下終了後、1時間ごとに13)と14)、15)と16)、17)と18)の各混合物を添加した。
17)と18)の混合物を添加した後、1時間経過してから不揮発分測定を行い反応完了を確認した。その後、19)〜20)を添加、冷却し、不揮発分32.7%、数平均分子量4800、重量平均17000、酸価277のアクリル樹脂溶液(a)を得た。
【0064】
〔エポキシ樹脂(B)〕
エポキシ樹脂類(B)は、ビスフェノールAを原料として用いた市販品b1〜b3を使用した。平均分子量、重量平均分子量、エポキシ当量を表1に示す。
【0065】
【表1】
Figure 2004203913
【0066】
〔フェノール樹脂溶液(h1)の製造〕
1)ビスフェノールA 400部
2)p−クレゾール 100部
3)37%ホルマリン 360部
4)25%アンモニア水 28部
【0067】
1)〜3)を窒素置換した反応釜に仕込み、加熱して70℃30分間攪拌して溶解した。55℃まで冷却し、4)を10〜15分かけて滴下した。発熱に注意しながら、70℃に温度制御した。70℃1時間反応後、n−ブタノール75%、キシレン25%の混合溶剤400部に抽出した。分離した水層を捨て、さらに溶剤層と同量の水を添加し、激しく攪拌後静置し水層を捨てた。溶剤層にジエチレングリコールモノブチルエーテル800部を加え、減圧で脱水・溶剤置換を行った。不揮発分26%、重量平均分子量2500のフェノール樹脂溶液(h1)を得た。
【0068】
〔フェノール樹脂溶液(h2)の製造〕
1)イオン交換水 80部
2)21.5%水酸化ナトリウム水溶液 72部
3)ビスフェノールA 140部
4)37%ホルマリン 400部
5)20%塩酸 70部
6)n−ブタノール 180部
7)ジエチレングリコールモノブチルエーテル 300部
【0069】
1)〜4)を順番に、窒素置換した反応釜に熱に注意しながら仕込み、50℃2時間と70℃1時間反応後40℃まで冷却し、5)と6)を仕込み攪拌して抽出した。分離した水層を捨て、さらに溶剤層と同量の水を添加し、激しく攪拌後静置し、水層を捨てた。溶剤層に7)を加え、減圧で脱水・溶剤置換を行った。不揮発分30%、重量平均分子量680のフェノール樹脂溶液(h2)を得た。
【0070】
[実施例1]
〔予備分散体(f1)の製造〕
Figure 2004203913
【0071】
1)〜4)を反応釜に仕込み、120℃2時間攪拌し溶解確認後、内温を105℃まで下げ、5)を添加し、アクリル樹脂とエポキシ樹脂の反応を開始した。105℃2時間で終点とし、部分反応樹脂溶液(E)を得た。粘度は32Pa・s/100℃(632Pa・s/70℃)であった。
6)を少しずつ断続的に添加、攪拌して、水と樹脂が十分に相溶していることを確認した。6)が4.9部添加された時点の粘度は160Pa・s/90℃であった。6)添加終了時点の粘度は215Pa・s/90℃であった。80℃に冷却した時点が最大粘度であり、824Pa・sであった。
【0072】
次いで、これに7)を添加した。7)の添加中に系の粘度が急激に低下し、電気伝導度が0〜10μSから500μSに急上昇し、転相が確認できた。7)添加終了時点で粘度は18Pa・s/70℃であった。従って70℃における粘度比は632/18=35となる。
この間の攪拌は10〜30rpm、剪断速度20〜60/秒で行った。
【0073】
更に8)と9)を添加混合して、予備分散体(f1)を得た。この時点の不揮発分は45.8%、粘度は40Pa・s/50℃、粒子径は6.1μmであった。
【0074】
予備分散体(f1)600gを、1L・直径8.5cmの円筒フラスコに移し、直径4cmのディスパー羽根6000回転(剪断速度560/秒)で攪拌微細化分散した。10分後の粒子径は3μm、60分後の粒子径は0.49μmであった。この分散体にイオン交換水と添加剤(消泡・湿潤剤)サーフィノール104を0.7g追加し、不揮発分33%、有機溶剤量15%、#4フォードカップの粘度が25℃で46秒の水性塗料(実1)を得た。
【0075】
[比較例1]
予備分散体(f1)600gを、1L・直径8.5cmの円筒フラスコに移し、最大径7.4cmの錨羽根100回転(剪断速度70/秒)で攪拌した。60分後の粒子径は変化なく、6.1μmであった。この分散体にイオン交換水と添加剤(消泡・湿潤剤)サーフィノール104を0.7g追加し、不揮発分33%、有機溶剤量15%、#4フォードカップの粘度が25℃で46秒の水性塗料(比1)を得たが、室温一週間以内に沈降分離してしまった。
【0076】
[比較例2]
〔予備分散体(f2)の製造〕
Figure 2004203913
【0077】
1〜6)まで、予備分散体(f1)の製造方法と同じ方法を用いた。
6)添加終了時点で、粘度を下げる目的で加温し90℃以上を保持しながら8)〜10)を少しずつ添加した。10)を添加終了後、11)を添加した。粘度は下がらず転相しなかった。得られた予備分散体(f2)の不揮発分は33.5%であった。強制的に多量の水を添加して分散させ粒子径を測定したところ、13μm以上であった。粒子径が大き過ぎるため、塗料の製造は行わなかった。
【0078】
[比較例3]
比較例2で用いた予備分散体(f2)と同じ組成を用いた。(f1)と同様にして1)〜4)を1L・直径8.5cmの円筒フラスコにしこみ、120℃2時間攪拌し溶解確認後、内温を105℃まで下げ、5)を添加し、アクリル樹脂とエポキシ樹脂の反応を105℃2時間行った。
次に、実施例1で予備分散体(f1)を微細化分散したときに用いた羽根と同じ直径4cmのディスパー羽根に交換した。十分に水と樹脂が相溶していることを確認し、できるだけ強く攪拌しながら6)を少しずつ断続的に添加したが、樹脂溶液が羽根に巻き上がるため十分に攪拌できなかった。また、温度管理もできないので中止した。
実施例と比較例について分散条件をまとめると、表2のようになる。
【0079】
【表2】
Figure 2004203913
【0080】
〔塗料性状・塗膜物性の評価〕
実施例1、比較例1で得られた水性塗料の塗料性状および塗膜物性を以下の方法で評価し、結果を表3に示した。
試験パネル作成条件:クロム処理鋼板100cm2あたりの乾燥塗膜厚が50〜60mgになるようにナチュラルロールコーターを用いて塗装し、200℃10分間焼付け乾燥した。
【0081】
(1)貯蔵安定性:塗料を50℃恒温器に保存し、定期的に外観、性状を目視にて評価した。
○:一ヶ月経過しても沈殿が生じない。
×:一週間経過後に沈殿が生じた。
(2)ピール剥離強度(下地密着性):ナイロン系接着剤を塗膜面ではさみ、200℃で熱圧着した5mm幅の試験片を用い、Tピール剥離強度を測定した。また、試験片を熱水中30分浸漬後冷却乾燥した後、Tピール剥離強度(処理後ピール剥離強度)を測定した。単位はkg/5mmで示した。
【0082】
(3)耐水性:パネルを耐圧釜にて125℃40分水中に浸漬後冷水で急冷し、塗膜の表面状態を観察した。
○:変化なし
△:部分的に白化
×:全面が白化
(4)加工性:塗装板の塗膜を外側にして二つ折にし、折り曲げ加工した。加工部位に食塩水を電解液として通電し電流値を測定し、以下の基準で評価した。
○:5mA未満
△:5〜50mA
×:50mAを超えたもの×として評価した。
【0083】
(5)耐フレーバー阻害性:塗装板試験片と活性炭処理水を満たした耐熱ガラス製ボトルにフタをし、蒸気殺菌処理した後の、内溶液のフレーバーの変化を調べ、以下の基準で評価した。
○:全く変化なし
△:少し変化あり
×:著しい変化あり
【0084】
【表3】
Figure 2004203913
表3に見られるように、本発明の水性樹脂分散体を用いると、貯蔵安定性、耐水性にすぐれ、かつ、塗料に必要とされるピール剥離強度(下地密着性)、加工性、耐フレーバー性も良好な塗料を提供できる。
【0085】
【発明の効果】
本発明は、一塩基酸モノマー30〜70重量%を含む重量平均分子量3000〜30000のアクリル樹脂(A)100重量部と、数平均分子量1400以上の芳香族系エポキシ樹脂(B)100〜1000重量部と、アミン類(C)10〜100重量部とを、アクリル樹脂(A)と芳香族系エポキシ樹脂(B)の合計に対して60重量%以下の有機溶剤(D)の存在下で部分反応させた部分反応樹脂溶液(E)を得た後、転相前においては剪断力をあまりかけずに攪拌して粗分散(工程1)し、転相後においては高剪断力をかけて攪拌して微細分散(工程2)しているので、高粘度の樹脂分散体においても平均粒子径1μm以下の水性樹脂分散体が得られる。
【0086】
また、工程1において、転相前の最大粘度(Vmax)が20Pa・s以上、かつ予備分散体(F)の粘度(VF)が100Pa・s以下であり、かつ、同一温度における部分反応樹脂溶液(E)の粘度(VE)と予備分散体(F)の粘度(VF)との粘度比P=(VE)/(VF)が、10〜500であるので、良好な水性樹脂分散体が得られる。
【0087】
特に、有機溶剤(D)の70重量%以上が水と自由に相互溶解する有機溶剤である場合においても、良好な水性樹脂分散体が得られる。更に水性樹脂分散体の粘性の非ニュートン流動性が軽減されるため、塗料とした場合に非常に優れたロールコート塗装適性を得ることができる。
【0088】
すなわち、本発明においては、比較的大きな分子量である樹脂を用い、使用する有機溶剤量が少ないにもかかわらず、比較的小さな動力で微細な粒子径の水性樹脂分散体が得られる。そして、この水性樹脂分散体を用いて優れた塗膜物性と貯蔵安定性のある水性塗料が得られる。
【図面の簡単な説明】
【図1】水滴崩壊に必要な臨界的剪断力の代表的理論を示すグラフである。
横軸:粘度比
縦軸:臨界Weber数(分裂限界時における無次元剪断速度)
(A):分裂しない領域
(B):分裂を起こす領域[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention is a method for producing an aqueous resin dispersion. Further, the present invention relates to an aqueous dispersion obtained by this production method and a paint having excellent storage stability, roll coatability, and coating film properties.
[0002]
[Prior art]
Since the storage stability of the aqueous resin dispersion is increased by reducing the particle diameter, various attempts have been made to make the aqueous resin dispersion finer. It is known that in order to obtain a fine aqueous resin dispersion, a high shearing force is required near the phase inversion point and that a shearing load is required for a certain time or more. And it has been thought that dispersion becomes impossible once the phase inversion point is left.
[0003]
As a typical theory, for example, as shown in FIG. 1, it has been considered that dispersion is impossible if the viscosity ratio P between (viscosity inside the dispersed particles) and (viscosity outside the dispersed particles) is 5 or less (for example, , Non-Patent Document 1.). Hereinafter, (viscosity inside dispersed particles) / (viscosity outside dispersed particles) is abbreviated as viscosity ratio P.
[0004]
In FIG.
(Critical Weber number) = (Minimum shear rate at which fragmentation occurs) × (Drop size at rest) × (Viscosity outside dispersed particles) / (Interfacial tension of droplet)
Is represented by
[0005]
The viscosity in the present invention is a value measured with a B-type viscometer # 4 rotor at 0.6 rpm for convenience unless a detailed description of the viscosity is required. If the value of 0.6 rpm could not be determined due to the very high or low viscosity, it was extrapolated by obtaining another rotation speed.
[0006]
If the (viscosity on the outside of the dispersed particles) is simply a viscosity of water of 1 mPa · s, a resin solution of 5 mPa · s or more cannot be miniaturized. Therefore, a viscosity ratio of 5 or less is considered to be an extremely large hurdle, and it has been considered that an aqueous resin dispersion having passed the phase inversion point cannot be refined by redispersion.
[0007]
For this reason, in the past, since a strong shear force was applied to one phase inversion point, there was a problem that when the treatment liquid became high in viscosity, not only enormous power was required but also heat generation could not be controlled. Was. In particular, this was a serious problem in the case of an aqueous resin dispersion that was vulnerable to high temperatures.
[0008]
When the amount of the organic solvent used is reduced from the viewpoint of environmental protection, it is necessary to reduce the size of the high-viscosity system. However, this required enormous power and was very difficult due to the intense heat generation.
[0009]
Conventionally, an organic solvent solution containing a carboxyl group-containing acrylic resin component, an epoxy resin component, and a curing agent resin component for an epoxy resin alone or in combination, and an aqueous solution of ammonia or amines are first used in an in-line mixer to form a W / O type. There is a method in which a dispersion is obtained, followed by further mixing water with a second-stage in-line mixer to obtain an O / W type aqueous resin dispersion (for example, see Patent Document 1).
[0010]
In this method, a large amount of an organic solvent is used, and a step of removing the solvent from the produced aqueous resin dispersion is required. The second stage in-line mixer process involves a phase change from W / O to O / W, which results in the highest viscosity during this dispersion process. To obtain fine particles, a large shearing force is required. However, when the amount of the organic solvent is reduced, the viscosity of the system is increased and the system cannot be dispersed by an in-line mixer, so that fine particles cannot be obtained.
[0011]
There is also a method in which a resin solution and water are introduced at a fixed rate at a time into a dispersing machine having a mixing and kneading section and a high-speed shearing mechanism section in the same container (for example, see Patent Document 2). In this method, the phase inversion point is exceeded at a stroke in the dispersing machine, the maximum viscosity is passed during the dispersion treatment, and a large load is applied.
[0012]
100 to 10,000 kg / cm 2 There is also disclosed a method of miniaturization by colliding with a flat portion at a pressure (for example, see Patent Document 3). Other miniaturized dispersing machines that collide an object after passing through a thin tube have been proposed.However, since pressure loss occurs during the process of passing through the thin tube and the work is extremely short, a high-viscosity product is required. In this case, the temperature cannot be controlled, and there is severe heat generation. In addition, since the action is a short time, depending on the type of the resin solution, the resin solution may be restored before miniaturization, and the effect may not be obtained.
[0013]
In addition, there are dispersers such as microdroplet forming devices (for example, see Patent Document 4), but they cannot cope with high-viscosity products.
[0014]
On the other hand, when high shear is applied near the phase inversion point or at the maximum viscosity, not only is an extremely powerful disperser required, but also intense heat generation is inevitable (see, for example, Patent Document 5).
[0015]
[Non-patent document 1]
Journal of Chemical Engineering, Vol. 2, No. 3 (1976), p. 244, FIG.
[Patent Document 1]
JP-A-1-292068
[Patent Document 2]
JP-A-4-220433
[Patent Document 3]
JP-A-5-98192
[Patent Document 4]
JP-A-8-196888
[Patent Document 5]
JP-A-2-261824
[0016]
[Problems to be solved by the invention]
As described above, an object of the present invention is to miniaturize and disperse a high-viscosity resin solution.
[0017]
[Means for Solving the Problems]
As a result of intensive studies, the present inventors have obtained several solutions and inventions.
The present inventors have verified the above theory and experiment, and as a result, the above discussion is a theory that is applicable to droplets with a clear particle interface, such as water and liquid paraffin, and in the case of an aqueous resin dispersion, I found something different.
First, it was considered appropriate to use the viscosity (VF) of the dispersion as the "viscosity outside the dispersion particles" which is a factor of the force acting on the dispersion particles from the outside.
[0018]
Further, the "viscosity inside the dispersed particles" itself is as follows: (1) that the solvent composition in the particles goes in and out of the particles to be in an equilibrium state; (2) that the equilibrium constant can be changed by the liquid temperature and other various conditions; 3) It may not be in an equilibrium state but may be in an unsteady state during transition. 4) It is difficult to measure directly due to small particles. 5) The equilibrium state is measured by means such as centrifugation. It is difficult to measure due to breakage and the like. However, since it is considered that the viscosity is close to the viscosity of the resin solution before the addition of water, in the present invention, the viscosity of the partially reacted resin solution (VE) before the addition of water is used as the "viscosity inside the dispersed particles". Therefore, in the present invention, the “viscosity ratio” P is set to (VE) / (VF).
[0019]
The inventors consider that the boundary surface of the aqueous resin dispersion is a continuously changing layer, and even if the ratio of the internal viscosity to the external viscosity of the particles = viscosity ratio P is not 5 or less, fine dispersion cannot be performed. As a result of repeated experiments, it was found that if the viscosity ratio was 500 or less, miniaturization was possible, and the present invention could be completed.
[0020]
That is, the first invention of the present invention is an acrylic epoxy resin (A) having a weight average molecular weight of 3,000 to 30,000 containing 30 to 70% by weight of a monobasic acid monomer, and an aromatic epoxy resin having a number average molecular weight of 1,400 or more. (B) 100 to 1000 parts by weight of an amine (C) and 10 to 100 parts by weight of an organic solvent (60% by weight or less based on the total of the acrylic resin (A) and the aromatic epoxy resin (B)) This is a method for producing an aqueous resin dispersion obtained by the following steps after obtaining a partially reacted resin solution (E) that has been partially reacted in the presence of D).
Step 1: Partial reaction resin solution (E) After adding water, stirring at a shear rate of 200 / sec or less and phase inversion to obtain an O / W type preliminary dispersion (F).
Step 2: The preliminary dispersion (F) is stirred at a shear rate of 400 / sec or more, and the resin-dispersed particles are finely dispersed to an average particle diameter of 1 μm or less.
[0021]
A second invention is a partial reaction resin solution having a maximum viscosity (Vmax) of 20 Pa · s or more before phase inversion, a viscosity (VF) of the preliminary dispersion (F) of 100 Pa · s or less, and the same temperature. The aqueous resin dispersion according to the first invention, wherein a viscosity ratio P = (VE) / (VF) between the viscosity (VE) of (E) and the viscosity (VF) of the preliminary dispersion (F) is 10 to 500. It is a method of manufacturing the body.
[0022]
The third invention is the method for producing an aqueous resin dispersion according to the first or second invention, wherein 70% by weight or more of the organic solvent (D) is an organic solvent that freely dissolves in water.
A fourth invention is an aqueous resin dispersion obtained by the method for producing an aqueous resin dispersion according to any one of the first to third inventions.
A fifth invention is a paint obtained by using the aqueous resin dispersion according to the fourth invention.
[0023]
The acrylic resin (A) used in the present invention is obtained by polymerizing a monobasic acid monomer and a copolymerizable monomer with a radical generator such as azobisisobutyronitrile or benzoyl peroxide as a catalyst.
[0024]
The monobasic acid monomer is a monomer containing a carboxylic acid such as acrylic acid or methacrylic acid. When the content of the monobasic acid monomer in the acrylic resin (A) is less than 30% by weight, it is difficult to make the partially reacted resin solution (E) aqueous. If the content exceeds 70% by weight, the acrylic resin (A) forms a salt with the amines (C) and is dissolved only in a highly polar solvent such as water. It is not preferable because the reaction with (B) is suppressed and the use is restricted.
[0025]
Examples of the copolymerizable acrylic monomer include acrylates such as methyl acrylate, ethyl acrylate, butyl acrylate and 2-ethylhexyl acrylate, methacrylates such as methyl methacrylate, and phenyl nuclei such as styrene and alpha methyl styrene. A monomer having a hydroxyl group such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, N-methylol (meth) acrylamide, a monomer having an N-substituted alkoxyl group such as N-methoxymethyl (meth) acrylamide, Other examples include acrylonitrile and glycidyl group-containing monomers. One or two or more of these can be selected and used.
[0026]
The molecular weight of the resin in the present invention is basically based on a weight average molecular weight in terms of styrene measured by GPC. This is because the number average molecular weight in the high molecular weight region handled in the present invention tends to cause an error in the numerical value due to slight unevenness of the baseline in the low molecular weight region. The number average molecular weight shows a reference value as the case may be.
[0027]
Styrene conversion is used because, although there is concern about errors due to differences in the polarity of the compounds, it is considered that the styrene conversion has already been widely used in the industry and common recognition has been obtained. Since styrene having a molecular weight standard is also commercially available, it can be determined that there is no need to particularly describe GPC measurement conditions.
[0028]
When polymerizing using the above monobasic acid monomer and copolymerizable monomer, an acrylic resin having an appropriate weight average molecular weight can be obtained by selecting the amount of the polymerization initiator and the reaction temperature. The acrylic resin (A) having a weight average molecular weight of 3,000 to 30,000 used in the present invention can be obtained by copolymerizing at a temperature of 70 to 150 ° C.
[0029]
If the weight average molecular weight is less than 3000, it is not possible to maintain an important and high level of coating film properties such as processability. If it exceeds 30,000, the aqueous coating cannot be used because the non-Newtonian fluidity becomes strong and the roll coatability deteriorates.
[0030]
The aromatic epoxy resin (B) having a number average molecular weight of 1400 or more used in the present invention is obtained by reacting a bifunctional phenol such as bisphenol A or bisphenol F with epichlorohydrin in the presence of an alkali catalyst to increase the molecular weight. Can be. If the number average molecular weight is less than 1400, it cannot be used because a high coating film property such as workability cannot be maintained. Those having a molecular weight exceeding 40,000 are rarely used. In particular, for coating applications, those having a molecular weight in the range of 3,000 to 30,000 are preferred.
[0031]
A resin having a glycidyl group at a terminal is called an epoxy resin and is generally commercially available. The amount of the glycidyl group can be adjusted by modifying the terminal glycidyl group with a phenolic hydroxyl group, alcohol, fatty acid or the like. Phenols are reacted to make phenolic hydroxyl groups at both ends substantially completely called phenoxy resin, but some glycidyl groups are intentionally left in the product group named phenoxy resin. There are some, and the boundary with the epoxy resin is not always clear. Therefore, in the present invention, all of them are included in the aromatic epoxy resin (B). All are commercially available.
[0032]
As typical examples, products of Japan Epoxy Resin Co., Ltd. include Epicoat 1009 and Epicoat 1010 using bisphenol A as a raw material, Epicoat 4010P using bisphenol F as a raw material, and phenoxy resin. There are Epicoat 4250 and Epicoat 1256.
[0033]
Examples of products of Toto Kasei Co., Ltd. include Epototo YD-019, Epototo YD-7019, and Epototo YD-7020 using bisphenol A as a raw material. Phenoxy resins include phenotote YP-50 and phenotote YP-70.
[0034]
Examples of the amines (C) used in the present invention include alkylamines such as ammonia and triethylamine, alcoholamines such as 2-dimethylaminoethanol, polyvalent amines such as ethylenediamine, morpholine, and pyridine.
[0035]
As the organic solvent (D) used in the present invention, when a newtonian fluidity is preferred, such as a roll coat, a solvent which can dissolve both resin and water well is selected as a main component. Preferably, 70% by weight or more of the organic solvent (D) is selected from organic solvents that freely dissolve in water.
[0036]
When the aqueous dispersion of the present invention is used as a paint, the boiling point of the solvent can be selected depending on the drying and baking conditions of the paint. In addition, the foaming / foaming property and wettability of the water-based paint can be selected according to various properties of the solvent such as surface tension.
[0037]
Specifically, several types are selected from the following solvents.
Examples of organic solvents that freely dissolve in water include ethanol, n-propanol, alkyl alcohols such as isopropanol, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, and diethylene glycol monopropyl ether. And ether alcohols such as diethylene glycol monobutyl ether, propylene glycol monomethyl ether and propylene glycol mono n-propyl ether, and ketone alcohols such as diacetone alcohol.
[0038]
As other solvents, n-butanol, isobutanol, hexyl alcohol, alkyl alcohols such as nonyl alcohol, ether alcohols having a large alkyl group such as ethylene glycol monohexyl ether, ether esters such as ethylene glycol monomethyl ether acetate, Esters such as ethyl acetate; ketones such as cyclohexanone;
[0039]
An acrylic resin (A) and an epoxy resin (B) are reacted in an organic solvent (D) using an amine (C) as a catalyst to obtain a partially reacted resin solution (E).
The organic solvent (D) is also required for the synthesis of the acrylic resin (A). As an example of a typical synthesis method which is not limited to the present invention, first, an acrylic resin (A) is synthesized in an organic solvent (D), and an epoxy resin (B) is added and dissolved therein. Thereafter, appropriate reaction conditions may be set, the amines (C) may be added, and the reaction may be started. As the reaction progresses, the acid value decreases, the epoxy equivalent increases, and the viscosity increases. Thus, the extent can be determined to determine the end point.
[0040]
If the reaction proceeds too much, the viscosity becomes too high, and if the reaction further proceeds too much, gelation generally occurs, which is not preferable. Since the viscosity and the physical properties of the coating film also vary depending on the degree of reaction, the end point of the reaction must be within an appropriate range. Since the unreacted acrylic resin component having an acid value dissolves in the aqueous phase, the aqueous resin dispersion is centrifuged, the non-volatile content of the aqueous phase is determined, and the ratio of the unreacted acrylic resin to the total resin is calculated. Since the ratio of resin / total acrylic resin can be quantified, the degree of reaction can be confirmed.
[0041]
The amount of each component in the method for producing an aqueous resin dispersion of the present invention is 100 to 1000 parts by weight of an epoxy resin (B) and 10 to 100 parts by weight of an amine (C) based on 100 parts by weight of an acrylic resin (A). is there. The amount of the organic solvent (D) is 60% by weight or less based on the total of (A) and (B). Particularly, 10 to 60% by weight is preferable.
[0042]
In the above, the ratio between the acrylic resin (A) and the epoxy resin (B) is selected in consideration of the balance between the viscosity of the paint and the physical properties of the coating film. The blending amount of the epoxy resin (B) with respect to 100 parts by weight of the acrylic resin (A) is 100 parts by weight or more from the viewpoint of processability and 1000 parts by weight or less from the viewpoint of poor non-Newtonian fluidity and good roll coat aptitude. . In particular, 100 to 500 parts by weight of the epoxy resin (B) is preferable for 100 parts by weight of the acrylic resin (A).
[0043]
After the end point of the reaction between the acrylic resin (A) and the epoxy resin (B) has been confirmed and the partially reacted resin solution (E) has been obtained, the following steps 1 and 2 are carried out to carry out the aqueous resin dispersion of the present invention. The body is obtained.
In step 1, water is added to and dispersed in the partial reaction resin solution (E) while stirring at a shear rate of 20 / sec or more, the phase reaches the phase inversion point after the maximum viscosity has passed, and the O / W type predispersion ( This is the step of obtaining F). In particular, the shear rate is preferably in the range of 20 to 200 / sec. The phase inversion point can be determined by a decrease in viscosity or a decrease in torque, or by electrical conductivity or visual observation. If the shear rate is less than 20 / sec, the stirring and mixing may not be performed substantially, and the heat conduction becomes poor.
[0044]
The shear rate is also commonly referred to as a velocity gradient and is defined as (velocity difference) / (distance). However, since this value is not uniform in the entire system of interest, it is not always clear what value is to be used as the representative value, and there are many complicated calculation methods. In the present invention, a method that can be easily calculated is used, and a value obtained by dividing a peripheral speed value of a pin of a stirring blade or a rotor at the time of rotation by a clearance with a container wall surface is used.
[0045]
That is, in the present invention, (shear speed [/ sec]) = (peripheral speed of the rotating body [m / sec]) / (clearance [m] between the rotating body and the container wall surface).
The phase inversion point can be known from a large change in the properties of the system, such as a sudden increase in electrical conductivity.
[0046]
In the phase inversion treatment in step 1, when water is added stepwise, the viscosity generally reaches a phase inversion point through a maximum value, though it varies depending on the type of resin, the type and amount of functional group, and the temperature. It is considered that the reason is that as the water is added, (1) the viscosity of the system rises due to a decrease in the temperature of the system, and (2) the resin solution phase and the water phase cannot be freely activated because they are hindered by the continuous phases of each other. Can be
[0047]
When the maximum viscosity Vmax of the dispersion in the step 1 is less than 20 Pa · s, it is not necessary to use the method of the present invention, and the phase inversion is performed in one stage by using a commonly used dispersing machine. can do.
[0048]
On the other hand, when the maximum viscosity Vmax of the dispersion is 20 Pa · s or more (no temperature limitation), it is difficult to obtain a fine dispersion by phase inversion in a conventional single step. When dispersing at a low shear rate using a high-viscosity type strong stirrer, fine particles having a particle size of 1 μm or less cannot be obtained. On the other hand, in the case of dispersing at a high shear rate, a dispersing machine such as a homogenizer or CLEARMIX, which sucks a liquid into a small area and makes it fine by a rotor and wall shearing, becomes difficult to suction and cannot be used. Further, in a disk-shaped high-speed stirring type disperser called a dissolver or a disper, a phenomenon in which a liquid wraps around a stirring disk and a stirring shaft appears, which also makes dispersion difficult.
[0049]
If the present invention is used, even if the maximum viscosity Vmax of the dispersion is 20 Pa · s or more (no temperature limitation), it is possible to perform preliminary phase dispersion and phase inversion beyond the maximum viscosity (step 1). Thereafter, fine dispersion is performed again under high shear to obtain fine particles having a particle diameter of 1 μm or less (Step 2).
[0050]
However, when the maximum viscosity Vmax of the dispersion further increases and the viscosity (VF) of the preliminary dispersion (F) exceeds 100 Pa · s even in the fine dispersion in the step 2, the method of the present invention is no longer used. However, fine dispersing becomes impossible with an ordinary dispersing machine.
That is, in Step 1, the maximum viscosity (Vmax) before phase inversion is 20 Pa · s or more, the viscosity (VF) of the preliminary dispersion (F) is 100 Pa · s or less, and the partially reacted resin solution at the same temperature. The viscosity ratio P = (VE) / (VF) between the viscosity (VE) of (E) and the viscosity (VF) of the preliminary dispersion (F) is particularly preferably from 10 to 500.
[0051]
In particular, when 70% by weight or more of the organic solvent (D) is composed of an organic solvent that freely dissolves in water, the water is added to the partially reacted resin solution (E) during the addition of water to the partially reacted resin solution (E). A phenomenon in which the solvent escapes into the aqueous phase occurs, and the viscosity of the resin solution phase increases. For this reason, conventionally, it was quite difficult to prepare an aqueous resin dispersion, but it became possible only by the method of the present invention.
[0052]
In the step 2, a high shearing force is applied to the preliminary dispersion (F) by stirring at a shear rate of 400 / sec or more, finely dispersed until the average particle diameter becomes 1 μm or less, cooled, and diluted with water to reduce the particle size of the emulsion. This is the process of trimming. In particular, the shear rate is preferably in the range of 400 to 10,000 / sec. By this step, the aqueous resin dispersion of the present invention is obtained.
[0053]
As indicated above, the present invention is a multi-stage dispersion method including a two-stage dispersion step, and step 2 is particularly important.
[0054]
In the step 2, the fine dispersion device X used for applying a high shearing force to the preliminary dispersion (F) has a structure and power capable of achieving a shear rate of 400 / sec or more, and has a residence time of 30 seconds or more. However, it is desirable to use a dispersing apparatus having a heating / cooling ability capable of keeping the temperature of the liquid during the treatment at 30 ° C. or more and less than 100 ° C. Although it depends on the pressure conditions, it is difficult to apply a shearing force when bubbles are generated.
[0055]
Examples of the fine dispersion apparatus X include a disk-type dispersion apparatus called a dissolver or a disper. Further, a combined emulsification apparatus described in JP-A-7-173294 or JP-A-8-117578, in which all steps can be performed in one reaction vessel by using a disc-type disperser and a low-speed stirrer in combination. Dispersing machines and the like can be mentioned.
[0056]
Specifically, a CABITRON homogenizer manufactured by Eurotech Co., Ltd. may be mentioned. For example, if this machine is used in Step 1, the dispersion will be poor because the capacity of the disperser will be exceeded. Therefore, in step 1, using a high-viscosity stirrer having a strong dispersing force but a low peripheral speed and a low shearing speed, coarse dispersion is performed at a shearing speed of 200 / sec or less, and a preliminary viscosity is passed through the phase inversion point through the highest viscosity region. A dispersion (F) is obtained.
[0057]
The viscosity of the dispersion solution in the subsequent step 2 is reduced to about 1/2 to 1/10 of the maximum viscosity in the step 1. Therefore, if this machine is used in the fine dispersion step of Step 2, stirring at a shear rate of 400 / sec or more is possible, and uniform shear can be applied to the entire dispersion solution, and fine dispersion can be performed. .
[0058]
When performing fine dispersion, an appropriate amount of water and an appropriate dispersion temperature are selected according to the purpose. If the amount of water to be added is too small, a special and powerful dispersing machine is required because the viscosity of the resin dispersion is high. Further, inconveniences such as increased heat generation occur. On the other hand, if the amount of water to be added is too large, the viscosity ratio P becomes 500 or more, and it becomes impossible to make finer. Therefore, the viscosity ratio P = (VE) / (VF) between the viscosity (VE) of the partially reacted resin solution (E) and the viscosity (VF) of the preliminary dispersion (F) is 4 to 500, preferably 10 to 100. Adjust the amount of water to be as follows.
At this time, since the viscosity of the preliminary dispersion (F) changes depending on the amount of water to be added, the temperature and the shear rate, the viscosity is measured at the same temperature and the same shear rate.
[0059]
In the method for producing an aqueous resin dispersion of the present invention, depending on the purpose, an organic solvent, a neutralizing agent, a surfactant, a defoaming agent, a slipping agent, a curing agent, and a rust inhibitor under appropriate conditions anywhere in the process. , Pigments, fillers and the like can be added and blended.
[0060]
Uses of the aqueous resin dispersion obtained by the production method of the present invention include paints. In this case, water is added to the obtained aqueous resin dispersion, and additives such as an antifoaming agent, a wetting agent, a slipping agent, and a curing agent, and the viscosity and the solid content are adjusted as necessary. The obtained paint can be applied to a metal plate such as a tin plate, a chrome-plated steel plate, tin-free steel, and an aluminum plate. It is particularly effective as a paint for the inner surface of a can.
As a coating method, a roll coater, spraying, electrodeposition coating and the like are possible, but the coating performance with the roll coater is excellent.
[0061]
【Example】
Hereinafter, the present invention will be described with reference to examples. In the examples, “parts” and “%” indicate “parts by weight” and “% by weight”, respectively. The viscosity was basically a stable value of 0.6 rpm with a B-type viscometer # 4 rotor. When a value could not be obtained at 0.6 rpm, the value was extrapolated from 0.3 rpm or a value of 1.5 to 30 rpm. The molecular weight was measured by GPC, and based on the weight average molecular weight in terms of styrene. Where a molecular weight distribution was required, the number average molecular weight and composition were shown as appropriate.
[0062]
[Production of acrylic resin solution (a)]
Figure 2004203913
[0063]
A 200 L reactor equipped with a stirrer, a nitrogen inlet tube, a water-cooled cooling tube, a temperature sensor, and a dropping tank was charged with 1) to 6) and heated to 130 ° C. with stirring. The mixed and dissolved 7) to 12) were put into a dropping tank, and the mixture was dropped over 2 hours while maintaining the temperature in the reactor at 130 ° C.
After the completion of the dropping, each mixture of 13) and 14), 15) and 16), 17) and 18) was added every hour.
One hour after the addition of the mixture of 17) and 18), measurement of the nonvolatile content was performed to confirm the completion of the reaction. Thereafter, 19) to 20) were added and the mixture was cooled to obtain an acrylic resin solution (a) having a nonvolatile content of 32.7%, a number average molecular weight of 4,800, a weight average of 17,000, and an acid value of 277.
[0064]
[Epoxy resin (B)]
As the epoxy resins (B), commercially available products b1 to b3 using bisphenol A as a raw material were used. Table 1 shows the average molecular weight, weight average molecular weight, and epoxy equivalent.
[0065]
[Table 1]
Figure 2004203913
[0066]
[Production of phenol resin solution (h1)]
1) Bisphenol A 400 parts
2) 100 parts of p-cresol
3) 360% 37% formalin
4) 25% ammonia water 28 parts
[0067]
1) to 3) were charged into a reaction vessel purged with nitrogen, heated and stirred at 70 ° C. for 30 minutes to dissolve. After cooling to 55 ° C, 4) was added dropwise over 10 to 15 minutes. The temperature was controlled at 70 ° C. while paying attention to heat generation. After reacting at 70 ° C. for 1 hour, extraction was performed with 400 parts of a mixed solvent of 75% n-butanol and 25% xylene. The separated aqueous layer was discarded, and the same amount of water as the solvent layer was further added. After vigorous stirring, the mixture was allowed to stand, and the aqueous layer was discarded. 800 parts of diethylene glycol monobutyl ether was added to the solvent layer, and dehydration and solvent replacement were performed under reduced pressure. A phenol resin solution (h1) having a nonvolatile content of 26% and a weight average molecular weight of 2500 was obtained.
[0068]
[Production of phenol resin solution (h2)]
1) 80 parts of ion exchange water
2) 21.5% aqueous sodium hydroxide solution 72 parts
3) Bisphenol A 140 parts
4) 400 parts of 37% formalin
5) 70% hydrochloric acid 70 parts
6) 180 parts of n-butanol
7) 300 parts of diethylene glycol monobutyl ether
[0069]
1) to 4) are sequentially charged into a nitrogen-purged reaction vessel while paying attention to heat, and after reaction at 50 ° C for 2 hours and 70 ° C for 1 hour, the reaction is cooled to 40 ° C, and 5) and 6) are charged and stirred for extraction. did. The separated aqueous layer was discarded, and the same amount of water as the solvent layer was further added. The mixture was vigorously stirred and allowed to stand, and the aqueous layer was discarded. 7) was added to the solvent layer, and dehydration and solvent replacement were performed under reduced pressure. A phenol resin solution (h2) having a nonvolatile content of 30% and a weight average molecular weight of 680 was obtained.
[0070]
[Example 1]
[Production of Preliminary Dispersion (f1)]
Figure 2004203913
[0071]
1) to 4) were charged into a reaction vessel, and stirred at 120 ° C. for 2 hours. After confirming dissolution, the internal temperature was lowered to 105 ° C., and 5) was added to start the reaction between the acrylic resin and the epoxy resin. The reaction was terminated at 105 ° C. for 2 hours to obtain a partially reacted resin solution (E). The viscosity was 32 Pa · s / 100 ° C (632 Pa · s / 70 ° C).
6) was added little by little intermittently and stirred, and it was confirmed that the water and the resin were sufficiently compatible. The viscosity at the time when 4.9 parts of 6) was added was 160 Pa · s / 90 ° C. 6) The viscosity at the end of the addition was 215 Pa · s / 90 ° C. The point at which it was cooled to 80 ° C. was the maximum viscosity, which was 824 Pa · s.
[0072]
Then, 7) was added to this. During the addition of 7), the viscosity of the system sharply decreased, and the electric conductivity sharply increased from 0 to 10 µS to 500 µS, and phase inversion was confirmed. 7) At the end of the addition, the viscosity was 18 Pa · s / 70 ° C. Therefore, the viscosity ratio at 70 ° C. is 632/18 = 35.
The stirring during this time was performed at 10 to 30 rpm at a shear rate of 20 to 60 / sec.
[0073]
Further, 8) and 9) were added and mixed to obtain a preliminary dispersion (f1). At this time, the nonvolatile content was 45.8%, the viscosity was 40 Pa · s / 50 ° C., and the particle size was 6.1 μm.
[0074]
600 g of the pre-dispersion (f1) was transferred to a 1 L / 8.5 cm diameter cylindrical flask, and dispersed by stirring and finely at 6000 revolutions (shear rate 560 / sec) of a 4 cm diameter disper blade. The particle diameter after 10 minutes was 3 μm, and the particle diameter after 60 minutes was 0.49 μm. To this dispersion, ion-exchanged water and 0.7 g of an additive (defoaming / wetting agent) Surfynol 104 were added, and the non-volatile content was 33%, the amount of organic solvent was 15%, and the viscosity of a # 4 Ford cup was 46 seconds at 25 ° C. Was obtained.
[0075]
[Comparative Example 1]
600 g of the preliminary dispersion (f1) was transferred to a cylindrical flask having a diameter of 1 L and a diameter of 8.5 cm, and stirred at 100 rotations of an anchor blade having a maximum diameter of 7.4 cm (shear speed: 70 / sec). The particle size after 60 minutes was unchanged and was 6.1 μm. To this dispersion, ion-exchanged water and 0.7 g of an additive (defoaming / wetting agent) Surfynol 104 were added, and the non-volatile content was 33%, the amount of organic solvent was 15%, and the viscosity of a # 4 Ford cup was 46 seconds at 25 ° C. Was obtained, but settled and separated within one week at room temperature.
[0076]
[Comparative Example 2]
[Production of Preliminary Dispersion (f2)]
Figure 2004203913
[0077]
1 to 6), the same method as the method for producing the preliminary dispersion (f1) was used.
6) At the end of the addition, 8) to 10) were added little by little while maintaining the temperature at 90 ° C. or higher for the purpose of decreasing the viscosity. After the addition of 10), 11) was added. The viscosity did not decrease and no phase inversion occurred. The nonvolatile content of the obtained preliminary dispersion (f2) was 33.5%. When a large amount of water was forcibly added and dispersed to measure the particle diameter, it was 13 μm or more. No coating was produced because the particle size was too large.
[0078]
[Comparative Example 3]
The same composition as the preliminary dispersion (f2) used in Comparative Example 2 was used. In the same manner as in (f1), 1) to 4) were placed in a 1 L / 8.5 cm diameter cylindrical flask, and stirred at 120 ° C. for 2 hours. After confirming dissolution, the internal temperature was lowered to 105 ° C., 5) was added, and acrylic was added. The reaction between the resin and the epoxy resin was performed at 105 ° C. for 2 hours.
Next, the preliminary dispersion (f1) in Example 1 was replaced with a disper blade having the same diameter of 4 cm as the blade used when finely dispersing. After confirming that the water and the resin were sufficiently compatible, 6) was added intermittently little by little while stirring as strongly as possible. However, the resin solution was wound around the blades, so that sufficient stirring could not be performed. In addition, we stopped because we could not control the temperature.
Table 2 summarizes the dispersion conditions for the example and the comparative example.
[0079]
[Table 2]
Figure 2004203913
[0080]
(Evaluation of paint properties and coating film properties)
The paint properties and coating film properties of the water-based paints obtained in Example 1 and Comparative Example 1 were evaluated by the following methods, and the results are shown in Table 3.
Test panel preparation conditions: chrome-treated steel sheet 100 cm Two The coating was applied using a natural roll coater so that the dry film thickness per unit became 50 to 60 mg, and baked and dried at 200 ° C. for 10 minutes.
[0081]
(1) Storage stability: The paint was stored in a thermostat at 50 ° C., and the appearance and properties were periodically evaluated by visual observation.
:: No precipitation occurs even after one month.
×: Precipitation occurred after one week.
(2) Peel peel strength (substrate adhesion): T-peel peel strength was measured using a 5 mm-wide test piece that was sandwiched between a coating film and a thermosetting adhesive at 200 ° C. After the test piece was immersed in hot water for 30 minutes and cooled and dried, the T-peel peel strength (peel peel strength after treatment) was measured. The unit was kg / 5 mm.
[0082]
(3) Water resistance: The panel was immersed in water at 125 ° C. for 40 minutes in a pressure cooker, quenched with cold water, and the surface state of the coating film was observed.
○: No change
Δ: Partial whitening
×: The entire surface is whitened
(4) Workability: The coated plate was folded in two with the coating on the outside, and bent. Electric current was applied to the processed part using a saline solution as an electrolyte, and the current value was measured, and evaluated based on the following criteria.
:: less than 5 mA
Δ: 5 to 50 mA
X: Evaluation was made as x, which exceeded 50 mA.
[0083]
(5) Flavor resistance: A coated plate test piece and a heat-resistant glass bottle filled with activated carbon-treated water were covered with a lid, and after steam sterilization, the change in flavor of the inner solution was examined and evaluated according to the following criteria. .
○: No change
△: slight change
×: marked change
[0084]
[Table 3]
Figure 2004203913
As shown in Table 3, when the aqueous resin dispersion of the present invention was used, the storage stability and water resistance were excellent, and the peeling strength (substrate adhesion), workability, and flavor resistance required for the paint were required. A paint having good properties can be provided.
[0085]
【The invention's effect】
The present invention relates to 100 parts by weight of an acrylic resin (A) having a weight average molecular weight of 3,000 to 30,000 containing 30 to 70% by weight of a monobasic acid monomer, and 100 to 1,000 parts by weight of an aromatic epoxy resin (B) having a number average molecular weight of 1,400 or more. Part and 10 to 100 parts by weight of amines (C) in the presence of 60% by weight or less of organic solvent (D) based on the total of acrylic resin (A) and aromatic epoxy resin (B). After obtaining the reacted partial reaction resin solution (E), before phase inversion, it is coarsely dispersed (step 1) by stirring without applying much shear force, and after phase inversion, it is stirred by applying high shear force. And fine dispersion (Step 2), an aqueous resin dispersion having an average particle diameter of 1 μm or less can be obtained even in a high-viscosity resin dispersion.
[0086]
In Step 1, the maximum viscosity (Vmax) before phase inversion is 20 Pa · s or more, the viscosity (VF) of the preliminary dispersion (F) is 100 Pa · s or less, and the partially reacted resin solution at the same temperature. Since the viscosity ratio P = (VE) / (VF) between the viscosity (VE) of (E) and the viscosity (VF) of the preliminary dispersion (F) is 10 to 500, a good aqueous resin dispersion is obtained. Can be
[0087]
In particular, even when 70% by weight or more of the organic solvent (D) is an organic solvent that freely dissolves in water, a good aqueous resin dispersion can be obtained. Furthermore, since the viscosity non-Newtonian fluidity of the aqueous resin dispersion is reduced, it is possible to obtain extremely excellent roll coat coating suitability when used as a paint.
[0088]
That is, in the present invention, a resin having a relatively large molecular weight is used, and an aqueous resin dispersion having a fine particle diameter can be obtained with relatively small power, despite the small amount of the organic solvent used. Then, an aqueous paint having excellent coating film properties and storage stability can be obtained using the aqueous resin dispersion.
[Brief description of the drawings]
FIG. 1 is a graph showing a typical theory of critical shear force required for water droplet collapse.
Horizontal axis: viscosity ratio
Vertical axis: Critical Weber number (Dimensionless shear rate at the limit of fission)
(A): Undivided area
(B): Area where division occurs

Claims (5)

一塩基酸モノマー30〜70重量%を含む重量平均分子量3000〜30000のアクリル樹脂(A)100重量部と、数平均分子量1400以上の芳香族系エポキシ樹脂(B)100〜1000重量部と、アミン類(C)10〜100重量部とを、アクリル樹脂(A)と芳香族系エポキシ樹脂(B)の合計に対して60重量%以下の有機溶剤(D)の存在下で部分反応させた部分反応樹脂溶液(E)を得た後、以下の工程により得られる水性樹脂分散体の製造方法。
工程1:部分反応樹脂溶液(E)水を添加しながら剪断速度200/秒以下で攪拌し転相させてO/W型の予備分散体(F)を得た後に、
工程2:予備分散体(F)を剪断速度400/秒以上で攪拌し、樹脂分散粒子を平均粒子径1μm以下に微細化分散する。
100 parts by weight of an acrylic resin (A) having a weight average molecular weight of 3000 to 30000 containing 30 to 70% by weight of a monobasic acid monomer, 100 to 1000 parts by weight of an aromatic epoxy resin (B) having a number average molecular weight of 1400 or more, and amine A part obtained by partially reacting 10 to 100 parts by weight of the class (C) with an organic solvent (D) in an amount of 60% by weight or less based on the total amount of the acrylic resin (A) and the aromatic epoxy resin (B). A method for producing an aqueous resin dispersion obtained by the following steps after obtaining a reactive resin solution (E).
Step 1: Partial reaction resin solution (E) After adding water, stirring at a shear rate of 200 / sec or less and phase inversion to obtain an O / W type preliminary dispersion (F).
Step 2: The preliminary dispersion (F) is stirred at a shear rate of 400 / sec or more, and the resin-dispersed particles are finely dispersed to an average particle diameter of 1 μm or less.
工程1において、転相前の最大粘度(Vmax)が20Pa・s以上、かつ予備分散体(F)の粘度(VF)が100Pa・s以下であり、かつ、同一温度における部分反応樹脂溶液(E)の粘度(VE)と予備分散体(F)の粘度(VF)との粘度比P=(VE)/(VF)が、10〜500である請求項1記載の水性樹脂分散体の製造方法。In Step 1, the maximum viscosity (Vmax) before phase inversion is 20 Pa · s or more, the viscosity (VF) of the preliminary dispersion (F) is 100 Pa · s or less, and the partially reacted resin solution (E) at the same temperature. 3) The viscosity ratio P = (VE) / (VF) of the viscosity (VE) of the preliminary dispersion (F) to the viscosity (VF) of the preliminary dispersion (F) is from 10 to 500. . 有機溶剤(D)の70重量%以上が水と自由に相互溶解する有機溶剤である請求項1又は2に記載の水性樹脂分散体の製造方法。The method for producing an aqueous resin dispersion according to claim 1 or 2, wherein 70% by weight or more of the organic solvent (D) is an organic solvent that freely dissolves in water. 請求項1〜3いずれかに記載の水性樹脂分散体の製造方法で得られる水性樹脂分散体。An aqueous resin dispersion obtained by the method for producing an aqueous resin dispersion according to claim 1. 請求項4に記載の水性樹脂分散体を用いて得られる塗料。A paint obtained by using the aqueous resin dispersion according to claim 4.
JP2002371259A 2002-12-24 2002-12-24 Preparation process and use of aqueous resin dispersion Pending JP2004203913A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105062169A (en) * 2015-08-18 2015-11-18 苏州赛斯德工程设备有限公司 Preparation method for paint for wind turbine blade

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105062169A (en) * 2015-08-18 2015-11-18 苏州赛斯德工程设备有限公司 Preparation method for paint for wind turbine blade

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