JP2004025769A - Water-resisting agent for inkjet recording material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water-resisting agent which can increase light fastness without reducing a recording density, coloring property and water-resistance of an inkjet recording material, and the inkjet recording material including the water-resisting agent. <P>SOLUTION: This water-resisting agent for an inkjet recording material contains a cationic polymer. In this case, the cationic polymer has (a) a monomer unit having a plurality of cationic groups, and (b) a monomer unit having an ultraviolet absorbing structure and/or a monomer unit having a light stability structure as the constituent units. <P>COPYRIGHT: (C)2004,JPO

Description

【００１７】
Ｒ^１１：水素原子又はメチル基
Ｒ^１２：炭素原子数１〜１０のアルキレン基又は炭素原子数１〜１０のオキシアルキレン基
Ｒ^１３：水素原子、炭素原子数１〜６のアルキル基又は炭素原子数１〜６のアルコキシ基
Ｙ：エステル結合、アミド結合、エーテル結合又はウレタン結合
ｍ：０〜１
式［ＩＩ］で表される化合物の具体例としては、２−ヒドロキシ−４−（メタ）アクリロイルオキシベンゾフェノン、２−ヒドロキシ４−（２−（メタ）アクリロイルオキシ）エトキシベンゾフェノン等があげられ、特に２−ヒドロキシ−４−（２−メタクリロイルオキシ）エトキシベンゾフェノンが好ましい。
【００１８】
上記式［ＩＩ］において、Ｒ^１２の炭素原子数が１０を超えて大きい場合やＲ^１３の炭素原子数が６を超えて大きい場合は、カチオン性ポリマーの疎水性が高くなって、水への溶解性が低下するので、いずれもあまり好ましくない。また、ｍの値が２を超えた場合も、同様に、水への溶解性が悪化する傾向となる。
なお、本明細書で「（メタ）アクリル」等の表記は、「アクリル又はメタクリル」等を表すものである。
【００１９】
【化４】

【００２０】
Ｒ^１１、Ｒ^１２、Ｒ^１３、Ｙ、ｍは式［ＩＩ］におけるものと同じ意味を表す。
Ｒ^１４：水素原子、炭素原子数１〜６のアルキル基又はハロゲン基
ｐ：０〜１
式［ＩＩＩ］で表される化合物の具体例としては、例えば、２−［２‘−ヒドロキシ−５’−（（メタ）アクリロイルオキシ）フェニル］ベンゾトリアゾール、２−［２‘−ヒドロキシ−３’−ｔｅｒｔ−ブチル−（メタクリロイルオキシ）フェニル］ベンゾトリアゾール、２−（２‘−ヒドロキシ−５−メチル）−３−ビニルフェニル］ベンゾトリアゾール等が挙げられ、特に２−［２‘−ヒドロキシ−５’−（メタクリロイルオキシ）フェニル］ベンゾトリアゾール、２−（２‘−ヒドロキシ−５−メチル）−３−ビニルフェニル］ベンゾトリアゾールが好ましい。
【００２１】
上記式［ＩＩＩ］において、Ｒ^１４の炭素原子数が６を超えて大きい場合は、やはりカチオン性ポリマーの水溶性が低下する傾向となる。Ｒ^１４として好ましいものは、水素原子、メチル基、エチル基等である。
（ａ２２）光安定性構造を有するモノマー単位（光安定性モノマー単位）
光安定性モノマー単位とは、一分子中に光安定性構造と重合性基とを有する化合物である。光安定性モノマー単位としては、ヒンダードアミン残基を有する重合性モノマーが好ましく、具体例としては式［ＩＶ］で表される化合物が挙げられる。これらの化合物は単独で用いても、二種類以上を組み合わせて用いてもよい。
【００２２】
【化５】

【００２３】
Ｒ^２１：炭素原子数１〜１０のアルキル基又は炭素原子数６〜１０のシクロアルキル基
Ｒ^２２：水素原子またはメチル基
Ｒ^２１のアルキル基としては、メチル基、エチル基、プロピル基、イソプロピル基、ブチル基、イソブチル基、ｔｅｒｔ−ブチル基、ペンチル基、ヘキシル基、ヘプチル基、オクチル基、ノニル基、デシル基、シクロペンチル基、シクロヘキシル基、シクロペンチルメチル基、シクロヘキシルメチル基などを例示することができる。中でも、Ｒ^２１としては、水素原子又はメチル基が好ましい。
（ａ３）分子内にカチオン変性可能な置換基とラジカル重合性不飽和基を有するモノマー
分子内にカチオン変性可能な置換基とラジカル重合性不飽和基を有するモノマー（ａ３）としては、アリルアミン、Ｎ−アルキルアリルアミン，ジアリルアミン、Ｎ，Ｎ−ジアルキルビニルベンズアミド、Ｎ，Ｎ−ジアルキル（メタ）アクリルアミド、Ｎ，Ｎ−ジアルキルアミノアルキル（メタ）アクリレート等が挙げらる。
【００２４】
このような分子内にカチオン変性可能な置換基とラジカル重合性不飽和基を有するモノマーを用いて共重合を行った場合は、共重合後にカチオン変性（四級化処理）を行う。カチオン変性は通常用いられている方法により、塩化メチル等の四級化剤を用いて行うことができる。
本発明の要件である複数のカチオン基を有するモノマー単位を得るためには、モノマーとして複数のカチオン変性可能な置換基を有する重合性モノマーを使用する方法の他に、カチオン化剤としてカチオン基を有する四級化剤を用いることによっても可能である。このような四級化剤としては、例えば３−クロロ−２−ヒドロキシプロピルトリメチルアンモニウムクロライド、３−クロロ−２−ヒドロキシプロピルドデシルジメチルアンモニウムクロライド等が挙げられる。
【００２５】
上記以外のモノマー単位も、本発明の目的・効果を損なわない限り、ラジカル重合性不飽和基を有するモノマーを特に制限なく用いることができる。例えば、スチレン、α−メチルスチレン、ビニルナフタレンなどの芳香族ビニル化合物、メチル（メタ）アクリレート、エチル（メタ）アクリレート、ブチル（メタ）アクリレート、シクロヘキシル（メタ）アクリレート、２−エチルヘキシル（メタ）アクリレート、ラウリル（メタ）アクリレート、ステアリル（メタ）アクリレートなどの炭素原子数が１〜１８の脂環式アルキルを含むアルキル（メタ）アクリレート、（メタ）アクリル酸等のα、β−不飽和カルボン酸、イタコン酸、マレイン酸、２−メチレングルタル酸等のα、β−不飽和ジカルボン酸、２−ヒドロキシエチル（メタ）アクリレート、２−ヒドロキシブチル（メタ）アクリレートなどの末端にヒドロキシル基を有する（メタ）アクリレート、酢酸ビニル、プロピオン酸ビニルなどのビニルエステル、オルガノポリシロキサン基を有するシリコーンマクロモノマー、（メタ）アクリルアミド、Ｎ−アルキロール（メタ）アクリルアミドなどの（メタ）アクリルアミド、（メタ）アクリロニトリル、ハロゲン化ビニルなどを使用することができる。
【００２６】
カチオン性ポリマー中のカチオン性モノマー単位（ａ１）の含有量は３０〜９０重量％が好ましく、更に好ましくは４０〜８０重量％である。カチオン性モノマー単位（ａ１）の含有量が３０重量％未満であるとインクの耐水性が悪くなる傾向となり、９９重量％を超えて多いとポリマー中の紫外線吸収性モノマー単位及び／又は光安定性モノマーの含有量が相対的に少なくなってしまい、十分な耐光性が得られないことがある。
【００２７】
紫外線吸収性モノマー単位（ａ２１）及び／又は光安定性モノマー単位（ａ２２）の含有量は５〜７０重量％が好ましく、更に好ましくは１０〜６０重量％である。
この含有量が５重量％未満では、耐光性が不十分となることがあり、一方７０重量％を超えて多い場合はカチオン性ポリマーの疎水性が高くなって水への溶解性が悪化することがある。
【００２８】
このカチオン性ポリマーの重量平均分子量は３０００〜５０００００の範囲であるのが好ましく、５０００〜２０００００であるのが更に好ましい。分子量が３０００未満のように低すぎるとポリマーが水に溶け出しやすくなりインクの耐水性が悪くなる。一方、分子量が５０００００を超えて高くなると、ポリマーの粘度が上昇して、取り扱いにくくなり、また他の成分との相溶性も悪くなる。なお、重量平均分子量は常法に従ってゲルパーミエイション・クロマトグラフィにより測定できる。
【００２９】
カチオン性ポリマーの製造方法は特に限定されず、通常用いられる重合方法を用いて製造することができる。好ましい製造方法は、ラジカル重合性開始剤を用いた溶液重合である。重合溶媒としては、メタノール、エタノール、イソプロパノール等のアルコール類、アセトン、メチルエチルケトン、メチルイソブチルケトン等のケトン類、酢酸エチル、酢酸ブチルなどのエステル類、テトラヒドロフラン、ジオキサン、ブチルセロソルブなどのエーテル類が挙げられる。開始剤にはα，α’−アゾビスイソブチロニトリル、２，２’−アゾビス（２−アミジノプロパン）ジハイドロクロライド等のアゾ系のラジカル重合開始剤、過硫酸カリウム、過硫酸アンモニウム等の過硫酸塩、ジ−α−クミルパーオキサイド、ベンゾイルパーオキサイド等のパーオキサイド等を用いることができる。重合は、上記溶媒中にて、温度５０〜１５０℃で２〜１２時間、好ましくは７０〜１２０℃で５〜１０時間行う。重合温度が低すぎると重合に長時間を要して経済的ではなく、高すぎると得られるポリマーの分子量が低くなる。また、反応時間が短かすぎると残存するモノマー量が多くなり、長すぎると生産性が低下する。
【００３０】
共重合後にカチオン変性を行う場合は、反応物の着色を抑えるため、窒素雰囲気下において、前述の水、アルコール類、ケトン類、エステル類、エーテル類等の適切な溶媒中で、共重合体に四級化剤を添加した後、６０〜１５０℃で２〜８０時間反応すればよい。
本発明の耐水化剤は、上述のポリマーに、必要に応じて通常使用される合成シリカ、アルミナなどの顔料、ポリビニルアルコール、ポリビニルピロリドン、ゼラチン、ポリアルキレンオキサイド、ヒドロキシアルキルセルロース、デンプンなどの水溶性高分子バインダーなどを混合併用して得ることができる。この耐水化剤を、サイズプレス、ロールコーター、バーコーター、エアナイフコーター、ブレードコーターなど、通常に使用されている塗工手段により、被記録材上に塗工して本発明のインクジェット用被記録材を製造することができる。
【００３１】
被記録材中の、上記特定のカチオン性ポリマーの塗工量は、画像の耐水性、耐光性の実用的な範囲を考慮すれば、０．０１〜１０ｇ／ｍ^２、好ましくは０．１〜５ｇ／ｍ^２　である。
なお、本発明の耐水化剤には、上記特定のポリマーの他に、顔料、バインダーや必要に応じて消泡剤、酸化防止剤、他の耐水化剤などを適宜配合することができる。
【００３２】
また、塗工後平面の平滑性、光沢性を向上させるため、スーパーカレンダー、グロスカレンダー等で処理することも可能である。
【００３３】
【実施例】
以下、実施例を用いて本発明を更に詳細に説明するが、本発明はその要旨を超えない限りこれらの実施例により限定されるものではない。
＜製造例１＞
攪拌機、冷却管を備えた５００ｍｌフラスコにジメチルアミノエチルメタクリレート４２ｇ、ベンゾトリアゾール系紫外線吸収性モノマー（ＲＵＶＡ−９３：構造は下式（Ｖ）の通り。大塚化学株式会社製）９ｇ、ヒンダードアミン系光安定性モノマー（ＬＡ−８２：構造は下式（ＶＩ）の通り。旭電化工業株式会社製）９ｇ、溶媒として酢酸エチル１４０ｇ、開始剤として２，２’−アゾビスイソブチロニトリル（ＡＩＢＮ）０．６ｇを仕込み、反応系内を窒素雰囲気に置換した後８０℃まで昇温し、重合を開始した。２時間後、ＡＩＢＮを０．０６ｇ追加し、さらに４時間重合を継続してカチオン性ポリマー用共重合体を得た。
【００３４】
上記の共重合体溶液にカチオン基を有する四級化剤として３−クロロ−２−ヒドロキシプロピルトリメチルアンモニウムクロライド６０重量％水溶液を８２ｇ添加し、次いで８０℃で２０時間四級化反応を行った後、蒸留水を投入し、酢酸エチルを留去して最終的に固形分１５重量％の水溶液を得た。
得られたカチオン性ポリマーは下式（ＶＩＩ）のような複数のカチオン基を有するモノマー単位を含む構造となっており、その重量平均分子量は２８０００であった。
【００３５】
【化６】

【００３６】
＜製造例２＞
ジメチルアミノエチルメタクリレートの量を３０ｇ、ベンゾトリアゾール系紫外線吸収性モノマー（ＲＵＶＡ−９３）の量を１５ｇ、ヒンダードアミン系光安定性モノマー（ＬＡ−８２）の量を１５ｇとしたこと以外は前記製造例１と同様にしてカチオン性ポリマー用共重合体を得た。
【００３７】
得られた共重合体の四級化処理を３−クロロ−２−ヒドロキシプロピルトリメチルアンモニウムクロライド６０重量％水溶液の量を５８．６ｇとしたこと以外は上記製造例１と同様にして実施し、固形分１５ｗｔ％の水溶液を得た。
得られたカチオン性ポリマーは、上記製造例１と同様の構造であり、重量平均分子量は２６０００であった。
＜製造例３＞
製造例１，２と同様の５００ｍｌフラスコにジメチルアミノエチルメタクリレート６０ｇ、溶媒としてイソプロパノール（ＩＰＡ）１４０ｇ、開始剤として２，２’−アゾビスイソブチロニトリル（ＡＩＢＮ）０．６ｇを仕込み、反応系内を窒素雰囲気に置換した後８０℃まで昇温し、重合を開始した。２時間後、ＡＩＢＮを０．０６ｇを追加し、さらに４時間重合を継続しカチオン性ポリマー製造用重合体を得た。
【００３８】
上記ポリマー溶液に３−クロロ−２−ヒドロキシプロピルトリメチルアンモニウムクロライド６０重量％水溶液を１１７．２ｇ添加し、次いで８０℃で２０時間四級化反応をおこなった後、蒸留水を投入し、ＩＰＡを留去して最終的に固形分１５ｗｔ％の水溶液を得た。
得られたカチオン性ポリマーは紫外線吸収構造も光安定性構造も有していないこと以外は上記製造例１と同様の構造であり、重量平均分子量は２６０００であった。
＜製造例４＞
ジメチルアミノエチルアクリレートの量を５９ｇ、ヒンダードアミン系光安定性モノマーとしてＬＡ−８２を２３ｇ、ＬＡ−８７（構造は下式（ＶＩＩＩ）の通り。旭電化工業株式会社製）を１５ｇそれぞれ使用し、溶媒としてメチルエチルケトン（ＭＥＫ）を２９１ｇ用い、開始剤の２，２’−アゾビスイソブチロニトリル（ＡＩＢＮ）の量を２．９ｇとしたこと以外は上記製造例１と同様にして重合を開始した。反応開始２時間後、ＡＩＢＮを０．５ｇを追加し、さらに４時間重合を継続してジメチルアミノ基含有ポリマーを得た。（このポリマーには四級化処理を行わなかったので、カチオン基は有していない。）
【００３９】
【化７】

【００４０】
＜実施例、比較例＞
（１）塗工紙の作成
１００ｍｌサンプル瓶にシリカゲル（徳山曹達：ファインシールＸ−３７）５ｇ、ポリビニルアルコール１０％水溶液（クラレ：ポバールＰＶＡ１１７）２０ｇ、各製造例のポリマー溶液を固形分として０．５ｇ、蒸留水３３．７５ｇを入れ、ペイントシェーカーで１０分間攪拌し分散した後、バーコーター（Ｎｏ．２０）で乾式ＰＰＣ用紙（中性紙）に３ｇ／ｍ^２の厚さとなるように塗工し、乾燥機にて８０℃で７分間乾燥した。その後、２３℃／湿度６０％ＲＨの恒温室中で１夜放置した。
（２）テストサンプル印字
インクジェットプリンター（Ｃａｎｏｎ：ＢＪＦ８７０）を用いて、上で作成した塗工紙にブラック、シアン、マゼンタ、イエローの各色を２ｃｍ×２ｃｍのベタ印字を行った後、２３℃／湿度６０％ＲＨの恒温室中で１夜放置した。
（３）評価方法
・耐光性
印字された試験片の各色の光学濃度（Ｏ．Ｄ）を光学濃度計（マクベス：ＲＤ９２０）にて測定し、キセノンウェザーメーターを用いてブラックパネル温度８０℃で２５０時間照射後の各色の光学濃度を比較した。
【００４１】
耐光性（％）＝１００×照射後のＯ．Ｄ／試験前のＯ．Ｄ
・耐水性
印字された試験片を常温で蒸留水に１分間浸漬した後、乾燥して、印字部分のインクの残存度を目視にて評価した。
目視評価の判断基準を以下の通り。
【００４２】
◎：インクのにじみ、流れがみられない
○：わずかにインクのにじみ、流れがみられるが実用上問題ないレベルである
△：インクがにじむ、または一部が流れる
×：インクが完全に流れ落ちる
評価結果を表１に示す。
【００４３】
【表１】

【００４４】
＜結果の評価＞
（１）実施例１、２で用いた本発明の耐水化剤に基づく被膜を有するインクジェット被記録材は、表１に示す通り、耐水性、耐光性のいずれも良好な結果となっている。
（２）比較例１では、（ｂ）成分の紫外線吸収性構造を有するモノマー単位及び／又は光安定性構造を有するモノマー単位を含まないカチオン性ポリマーを使用しており、耐水性は良好であるが、耐光性は不十分であった。
（３）比較例２では、ポリマーが水に不溶で、塗膜が不均一であった。また耐光性は良好であるが、耐水性が劣っている。
【００４５】
【発明の効果】
上述の通り、本発明により優れた耐水性、耐光性を有するインクジェット用耐水化剤およびインクジェット被記録材を提供することができる。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a waterproofing agent applied to a recording material for ink jet recording and an ink jet recording material containing the same. By using the water-proofing agent of the present invention, it is possible to provide an ink-jet recording material having a receptor layer having particularly excellent water resistance and light resistance of the ink.
[0002]
[Prior art]
The inkjet recording method is widely applied to various printers as a non-impact recording method capable of full-color printing and image recording. Ink for ink jet recording is mainly composed of a dye, and conventionally, high quality paper or the like has been used as a recording material. However, recently, with the demand for high-speed, multi-color, and high-quality printing / images of ink-jet recording machines, recording materials also have problems such as ink absorbency and optical density of printing. In addition to good printing performance, performance such as water resistance of printed images and image retention during storage (prevention of fading) has been required. In particular, there is a strong demand for yellowing resistance of the ink receiving layer due to long-term light irradiation and prevention of deterioration of recorded images.
[0003]
Some proposals have been made to solve these problems. For the purpose of improving light fastness, for example, a method of adding a dithiocarbamate, a thiuram salt, a thiocyanate, a thiocyanate, a hindered amine or the like is proposed in JP-A-7-314882 and JP-A-10-330664. Further, a method for incorporating an ultraviolet absorber having a specific structure into a receptor layer is disclosed in JP-A-9-254522, JP-A-10-217600, JP-A-11-78218, and JP-A-11-99740. Although proposed in gazettes and the like, the additive used here is a low molecular compound and has a problem of lacking durability.
[0004]
In order to solve this durability problem, using a polymer having a monomer having a cationic group such as a quaternary ammonium base and a monomer having an ultraviolet absorbing ability as a structural unit as a polymer type ultraviolet absorber, Some attempts to simultaneously solve the water resistance and the light resistance have been proposed (JP-A-8-183242, JP-A-10-29369, JP-A-10-233592, and JP-A-11-20302). Gazette). However, many UV absorbers are hardly soluble in water, and copolymers with cationic group-containing monomers as described above are poorly soluble and dispersible in water, which is the solvent of the coating solution, and are thus obtained. Often becomes non-uniform and the image quality deteriorates. Further, even if a water-dispersible cationic copolymer is used, at present, all of the image quality, water resistance, and light resistance are not sufficiently satisfied.
[0005]
[Problems to be solved by the invention]
An object of the present invention is to provide a water-proofing agent capable of improving the light fastness without lowering the recording density, color developability, and water resistance of the ink-jet recording material, and an ink-jet recording material containing the water-proofing agent. That is.
[0006]
[Means for Solving the Problems]
The present inventors have conducted intensive studies to solve the above problems, and found that good results can be obtained by using a waterproofing agent containing a cationic polymer as described below. Waterproofing agents and inkjet recording materials were completed.
[0007]
That is, the gist of the present invention is that (a) a monomer unit having a plurality of cationic groups (hereinafter referred to as “cationic monomer unit”) and (b) a monomer unit having an ultraviolet absorbing structure (hereinafter referred to as “ultraviolet absorbing monomer”). A water-resistant agent for an ink-jet recording material, comprising a cationic polymer having, as a structural unit, a monomer unit having a light-stable structure (hereinafter referred to as a “unit”) and / or a monomer unit having a light-stable structure. It exists in
[0008]
Another gist of the present invention resides in the above-mentioned waterproofing agent for an ink jet recording material, wherein the cationic monomer unit (a) is represented by the following formula [I].
[0009]
Embedded image
_{^{CH 2 = CR 1 -COAR 2 -N}} + R 3 R 4 - (R 5 -N + R 6 R 7) n -R 8 · (n + 1) (X -)
[I]
However, the symbols in the formula indicate the following contents.
[0010]
A: oxygen atom or imino group R ¹ : hydrogen atom or methyl group R ² , R ⁵ : alkylene group having 1 to 12 carbon atoms R ³ , R ⁴ , R ⁶ , R ⁷ which may be substituted by a hydroxyl group , R ⁹ : an alkyl group having 1 to 4 carbon atoms, each independently R ⁸ : an alkyl group having 1 to 12 carbon atoms, an aralkyl group, or —CH ₂ COOR ⁹
X ⁻ : counter ion n: an integer of 1 to 3 Another gist of the present invention is that the ultraviolet-absorbing monomer unit (b) is a 2-hydroxybenzophenone residue or a 2′-hydroxyphenylbenzotriazole residue. The water-proofing agent for an ink jet recording material described above, and the water-resistant agent for an ink jet recording material described above, wherein the light-stable monomer unit (b) is a hindered amine residue.
[0011]
Another gist of the present invention resides in an ink jet recording material containing the above-mentioned waterproofing agent for an ink jet recording material on or in a support.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail.
The present invention has a great feature in that a polymer containing the specific cationic group, the ultraviolet absorbing structure and / or the photostable structure as a copolymerized unit is used.
(A) Cationic polymer The cationic polymer used in the present invention includes a monomer (a1) having a cationic group and a radical polymerizable unsaturated group in a molecule as described below, and an ultraviolet-absorbing monomer (a21) and / or A monomer (a3) having a substituent capable of cation modification in the molecule and a radically polymerizable unsaturated group and a UV-absorbing monomer (a21) and / or a light-stable monomer are copolymerized with the light-stable monomer (a22). It can be formed by copolymerizing with the reactive monomer (a22) and then performing cation modification.
(A1) Cationic monomer unit As the monomer unit having a plurality of cationic groups (cationic monomer unit) used in the water-proofing agent of the present invention, a single type or a combination of two or more types may be used. It does not matter.
[0013]
As the cationic monomer unit, those represented by the above formula [I] are preferable. Specifically, as an alkylene group having 1 to 12 carbon atoms which may be substituted with a hydroxyl group represented by R ² and R ⁵ , an ethylene group, a propylene group, an isopropylene group, a butylene group, a hydroxyethylene group, 1,2-dihydroxypropylene group, 1-hydroxypropylene group, 2-hydroxyisopropylene group, 1,2-dihydroxyisopropylene group, 2,3-dihydroxyisopropylene group, 1,2-tri Examples thereof include a hydroxybutylene group. Among them, R ² is preferably an alkylene group having 2 to 12 carbon atoms, and R ⁵ is preferably a 2-hydroxypropylene group. When the number of carbon atoms of R ² and R ⁵ exceeds 12, the hydrophobicity of the cationic polymer increases, and the water solubility tends to deteriorate.
[0014]
Examples of the alkyl group having 1 to 4 carbon atoms represented by R ³ , R ⁴ , R ⁶ , R ⁷ and R ⁹ include a methyl group, a propyl group, an isopropyl group and a butyl group. When the number of carbon atoms of these alkyl groups exceeds 4 and becomes large, the hydrophobicity of the cationic polymer increases, and the water solubility tends to deteriorate.
Examples of the alkyl group having 1 to 12 carbon atoms represented by R ⁸ include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, a pentyl group, a hexyl group, a heptyl group, An octyl group, a nonyl group, a decyl group, a cyclopentyl group, a cyclohexyl group, a cyclopentylmethyl group, a cyclohexylmethyl group, and the like can be given.Examples of the aralkyl group include a benzyl group, a methylbenzyl group, a phenethyl group, and a naphthylmethyl group. No.
[0015]
X ⁻ is preferably a chlorine ion, a bromine ion, an iodine ion, an alkyl sulfate ion or the like.
(A2) Monomer unit having an ultraviolet absorbing structure, monomer unit having a light stable structure (a21) Monomer unit having an ultraviolet absorbing structure (ultraviolet absorbing monomer unit)
The monomer unit having an ultraviolet absorbing structure is a compound having an ultraviolet absorbing structure and a polymerizable group in one molecule. Examples of the ultraviolet absorbing structure include a 2-hydroxybenzophenone residue, a 2'-hydroxyphenylbenzotriazole residue, and a cinnamic acid residue. Among these, polymerizable monomers having a 2-hydroxybenzophenone residue or a 2′-hydroxyphenylbenzotriazole residue are preferable from the viewpoint of the ability to absorb ultraviolet light, and specific examples thereof are represented by formulas [II] and [III]. Compounds to be used. These compounds may be used alone or in combination of two or more.
[0016]
Embedded image

[0017]
R ¹¹ : hydrogen atom or methyl group R ¹² : alkylene group having 1 to 10 carbon atoms or oxyalkylene group having 1 to 10 carbon atoms R ¹³ : hydrogen atom, alkyl group having 1 to 6 carbon atoms or carbon atom 1 to 6 alkoxy groups Y: ester bond, amide bond, ether bond or urethane bond m: 0 to 1
Specific examples of the compound represented by the formula [II] include 2-hydroxy-4- (meth) acryloyloxybenzophenone, 2-hydroxy-4- (2- (meth) acryloyloxy) ethoxybenzophenone, and the like. 2-hydroxy-4- (2-methacryloyloxy) ethoxybenzophenone is preferred.
[0018]
In the above formula [II], when the number of carbon atoms of R ¹² is larger than 10 or the number of carbon atoms of R ¹³ is larger than 6, the hydrophobicity of the cationic polymer increases, and Either is not preferred because the solubility is reduced. Also, when the value of m exceeds 2, the solubility in water also tends to deteriorate.
In the present specification, the notation such as “(meth) acryl” indicates “acryl or methacryl” or the like.
[0019]
Embedded image

[0020]
R ¹¹ , R ¹² , R ¹³ , Y and m have the same meaning as in formula [II].
R ¹⁴ : a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or a halogen group p: 0 to 1
Specific examples of the compound represented by the formula [III] include, for example, 2- [2′-hydroxy-5 ′-((meth) acryloyloxy) phenyl] benzotriazole, 2- [2′-hydroxy-3 ′ -Tert-butyl- (methacryloyloxy) phenyl] benzotriazole, 2- (2'-hydroxy-5-methyl) -3-vinylphenyl] benzotriazole and the like, particularly 2- [2'-hydroxy-5 ' -(Methacryloyloxy) phenyl] benzotriazole and 2- (2'-hydroxy-5-methyl) -3-vinylphenyl] benzotriazole are preferred.
[0021]
In the above formula [III], when the number of carbon atoms of R ¹⁴ is larger than 6, the water solubility of the cationic polymer also tends to decrease. Preferred as R ¹⁴ are a hydrogen atom, a methyl group, an ethyl group and the like.
(A22) Monomer unit having a light stable structure (light stable monomer unit)
The light-stable monomer unit is a compound having a light-stable structure and a polymerizable group in one molecule. The light-stable monomer unit is preferably a polymerizable monomer having a hindered amine residue, and specific examples include a compound represented by the formula [IV]. These compounds may be used alone or in combination of two or more.
[0022]
Embedded image

[0023]
R ²¹ : an alkyl group having 1 to 10 carbon atoms or a cycloalkyl group having 6 to 10 carbon atoms R ²² : a hydrogen atom or a methyl group As the alkyl group of R ²¹ , a methyl group, an ethyl group, a propyl group, an isopropyl group Butyl, isobutyl, tert-butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclohexylmethyl, etc. . Among them, R ²¹ is preferably a hydrogen atom or a methyl group.
(A3) Monomer having a cation-modifiable substituent and a radically polymerizable unsaturated group in the molecule Monomer having a cation-modifiable substituent and a radically polymerizable unsaturated group in the molecule (a3) includes allylamine, N -Alkylallylamine, diallylamine, N, N-dialkylvinylbenzamide, N, N-dialkyl (meth) acrylamide, N, N-dialkylaminoalkyl (meth) acrylate and the like.
[0024]
When copolymerization is performed using such a monomer having a cation-modifiable substituent and a radical polymerizable unsaturated group in the molecule, cation modification (quaternization treatment) is performed after the copolymerization. The cation modification can be performed by a commonly used method using a quaternizing agent such as methyl chloride.
In order to obtain a monomer unit having a plurality of cationic groups, which is a requirement of the present invention, in addition to a method of using a polymerizable monomer having a plurality of cation-modifiable substituents as a monomer, a cationic group is used as a cationizing agent. It is also possible by using a quaternizing agent. Examples of such a quaternizing agent include 3-chloro-2-hydroxypropyltrimethylammonium chloride, 3-chloro-2-hydroxypropyldodecyldimethylammonium chloride, and the like.
[0025]
As the monomer unit other than the above, a monomer having a radically polymerizable unsaturated group can be used without any particular limitation as long as the object and effects of the present invention are not impaired. For example, styrene, α-methylstyrene, aromatic vinyl compounds such as vinylnaphthalene, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, Α, β-unsaturated carboxylic acids, such as lauryl (meth) acrylate, stearyl (meth) acrylate, and other alkyl (meth) acrylates having 1 to 18 carbon atoms, including alicyclic alkyls; (meth) acrylic acid; (Meth) acrylate having a hydroxyl group at a terminal such as α, β-unsaturated dicarboxylic acid such as acid, maleic acid and 2-methylene glutaric acid, 2-hydroxyethyl (meth) acrylate, and 2-hydroxybutyl (meth) acrylate , Vinyl acetate, vinyl propionate (Meth) acrylamide such as (meth) acrylamide, N-alkylol (meth) acrylamide, (meth) acrylonitrile, vinyl halide and the like. it can.
[0026]
The content of the cationic monomer unit (a1) in the cationic polymer is preferably from 30 to 90% by weight, and more preferably from 40 to 80% by weight. If the content of the cationic monomer unit (a1) is less than 30% by weight, the water resistance of the ink tends to deteriorate, and if it exceeds 99% by weight, the ultraviolet absorbing monomer unit and / or the light stability in the polymer will be high. In some cases, the content of the monomer becomes relatively small, and sufficient light resistance may not be obtained.
[0027]
The content of the ultraviolet absorbing monomer unit (a21) and / or the photostable monomer unit (a22) is preferably from 5 to 70% by weight, more preferably from 10 to 60% by weight.
If the content is less than 5% by weight, the light resistance may be insufficient. If the content is more than 70% by weight, the hydrophobicity of the cationic polymer may be increased and the solubility in water may be deteriorated. There is.
[0028]
The weight average molecular weight of the cationic polymer is preferably in the range of 3,000 to 500,000, more preferably 5,000 to 200,000. If the molecular weight is too low, such as less than 3000, the polymer tends to dissolve in water and the water resistance of the ink deteriorates. On the other hand, when the molecular weight is higher than 500,000, the viscosity of the polymer increases, making it difficult to handle, and the compatibility with other components becomes poor. The weight average molecular weight can be measured by gel permeation chromatography according to a conventional method.
[0029]
The method for producing the cationic polymer is not particularly limited, and the cationic polymer can be produced using a commonly used polymerization method. A preferred production method is solution polymerization using a radically polymerizable initiator. Examples of the polymerization solvent include alcohols such as methanol, ethanol, and isopropanol; ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone; esters such as ethyl acetate and butyl acetate; and ethers such as tetrahydrofuran, dioxane, and butyl cellosolve. Examples of the initiator include azo radical polymerization initiators such as α, α′-azobisisobutyronitrile and 2,2′-azobis (2-amidinopropane) dihydrochloride, and peroxides such as potassium persulfate and ammonium persulfate. Sulfates, peroxides such as di-α-cumyl peroxide and benzoyl peroxide can be used. The polymerization is performed in the above solvent at a temperature of 50 to 150 ° C for 2 to 12 hours, preferably at 70 to 120 ° C for 5 to 10 hours. If the polymerization temperature is too low, it takes a long time for the polymerization, which is not economical, and if it is too high, the molecular weight of the obtained polymer becomes low. On the other hand, if the reaction time is too short, the amount of the remaining monomer increases, and if the reaction time is too long, the productivity decreases.
[0030]
When cation modification is performed after copolymerization, in order to suppress coloring of the reaction product, in a suitable solvent such as water, alcohols, ketones, esters, and ethers described above, under a nitrogen atmosphere, the copolymer After adding the quaternizing agent, the reaction may be performed at 60 to 150 ° C. for 2 to 80 hours.
The water-proofing agent of the present invention may be used in the above-mentioned polymers, if necessary, in general, synthetic silica, pigments such as alumina, polyvinyl alcohol, polyvinylpyrrolidone, gelatin, polyalkylene oxide, hydroxyalkyl cellulose, and water-soluble polymers such as starch. It can be obtained by mixing and using a polymer binder and the like. The water-proofing agent is coated on a recording material by a commonly used coating means such as a size press, a roll coater, a bar coater, an air knife coater, a blade coater, and the like, and the inkjet recording material of the present invention is applied. Can be manufactured.
[0031]
The coating amount of the specific cationic polymer in the recording material is 0.01 to 10 g / m ² , preferably 0.1 to 10 in consideration of a practical range of water resistance and light resistance of an image. 5 g / m ² .
The water-proofing agent of the present invention may contain, in addition to the above-mentioned specific polymer, a pigment, a binder, and if necessary, an antifoaming agent, an antioxidant, and other water-proofing agents.
[0032]
Further, in order to improve the smoothness and glossiness of the flat surface after coating, it is also possible to use a super calender, a gloss calender or the like.
[0033]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples unless it exceeds the gist.
<Production Example 1>
In a 500 ml flask equipped with a stirrer and a condenser, 42 g of dimethylaminoethyl methacrylate, 9 g of a benzotriazole-based UV-absorbing monomer (RUVA-93: structure is as shown in the following formula (V), manufactured by Otsuka Chemical Co., Ltd.), and hindered amine-based photostable 9g of a reactive monomer (LA-82: the structure is as shown in the following formula (VI); manufactured by Asahi Denka Kogyo KK), 140 g of ethyl acetate as a solvent, and 2,2'-azobisisobutyronitrile (AIBN) 0 as an initiator Then, the reaction system was replaced with a nitrogen atmosphere and heated to 80 ° C. to start polymerization. Two hours later, 0.06 g of AIBN was added, and the polymerization was further continued for 4 hours to obtain a copolymer for a cationic polymer.
[0034]
After adding 82 g of a 60% by weight aqueous solution of 3-chloro-2-hydroxypropyltrimethylammonium chloride as a quaternizing agent having a cationic group to the above copolymer solution, and then performing a quaternization reaction at 80 ° C. for 20 hours, Then, distilled water was added thereto, and ethyl acetate was distilled off to finally obtain an aqueous solution having a solid content of 15% by weight.
The resulting cationic polymer had a structure containing a monomer unit having a plurality of cationic groups as represented by the following formula (VII), and had a weight average molecular weight of 28,000.
[0035]
Embedded image

[0036]
<Production Example 2>
Production Example 1 except that the amount of dimethylaminoethyl methacrylate was 30 g, the amount of the benzotriazole-based UV-absorbing monomer (RUVA-93) was 15 g, and the amount of the hindered amine-based light-stable monomer (LA-82) was 15 g. In the same manner as in the above, a copolymer for a cationic polymer was obtained.
[0037]
The quaternization treatment of the obtained copolymer was carried out in the same manner as in Production Example 1 except that the amount of a 60% by weight aqueous solution of 3-chloro-2-hydroxypropyltrimethylammonium chloride was changed to 58.6 g. An aqueous solution of 15% by weight was obtained.
The resulting cationic polymer had the same structure as in Production Example 1 above, and had a weight average molecular weight of 26,000.
<Production Example 3>
The same 500 ml flasks as in Production Examples 1 and 2 were charged with 60 g of dimethylaminoethyl methacrylate, 140 g of isopropanol (IPA) as a solvent, and 0.6 g of 2,2′-azobisisobutyronitrile (AIBN) as an initiator. After replacing the inside with a nitrogen atmosphere, the temperature was raised to 80 ° C. to initiate polymerization. Two hours later, 0.06 g of AIBN was added, and the polymerization was further continued for 4 hours to obtain a polymer for producing a cationic polymer.
[0038]
To the polymer solution, 117.2 g of a 60% by weight aqueous solution of 3-chloro-2-hydroxypropyltrimethylammonium chloride was added, and then a quaternization reaction was performed at 80 ° C. for 20 hours. Finally, an aqueous solution having a solid content of 15 wt% was obtained.
The obtained cationic polymer had the same structure as that of Production Example 1 except that it had neither an ultraviolet absorbing structure nor a light-stable structure, and had a weight average molecular weight of 26,000.
<Production Example 4>
Using 59 g of dimethylaminoethyl acrylate, 23 g of LA-82 as a hindered amine light-stable monomer, and 15 g of LA-87 (the structure is as shown in the following formula (VIII); manufactured by Asahi Denka Kogyo Co., Ltd.), and the solvent was used. The polymerization was started in the same manner as in Production Example 1 except that 291 g of methyl ethyl ketone (MEK) was used, and the amount of 2,2′-azobisisobutyronitrile (AIBN) as the initiator was 2.9 g. Two hours after the start of the reaction, 0.5 g of AIBN was added, and the polymerization was further continued for 4 hours to obtain a dimethylamino group-containing polymer. (Since this polymer was not subjected to a quaternization treatment, it did not have a cationic group.)
[0039]
Embedded image

[0040]
<Examples and Comparative Examples>
(1) Preparation of coated paper In a 100 ml sample bottle, 5 g of silica gel (Tokuyama Soda: Fine Seal X-37), 20 g of a 10% aqueous solution of polyvinyl alcohol (Kuraray: Poval PVA117), and the solid content of the polymer solution of each production example was 0.1 g. 5 g and 33.75 g of distilled water were added, and the mixture was stirred and dispersed with a paint shaker for 10 minutes, and then coated with a bar coater (No. 20) on dry PPC paper (neutral paper) to a thickness of 3 g / m ^2. Then, it was dried at 80 ° C. for 7 minutes in a drier. Then, it was left overnight in a constant temperature room of 23 ° C./60% RH.
(2) Test sample printing Using an inkjet printer (Canon: BJF870), black, cyan, magenta, and yellow were printed in a solid color of 2 cm × 2 cm on the coated paper prepared above, followed by 23 ° C./humidity. It was left overnight in a constant temperature room of 60% RH.
(3) Evaluation method-Light resistance The optical density (OD) of each color of the printed test piece was measured with an optical densitometer (Macbeth: RD920), and the color density was measured at 250 ° C using a xenon weather meter at a black panel temperature of 80 ° C. The optical density of each color after the time irradiation was compared.
[0041]
Lightfastness (%) = 100 × O. D / O. D
-The test piece on which the water-resistant print was performed was immersed in distilled water at room temperature for 1 minute, dried, and the remaining amount of the ink in the print portion was visually evaluated.
The criteria for visual evaluation are as follows.
[0042]
◎: Ink bleeding, no flow observed ○: Slightly ink bleeding, flow observed, but at a level that is not problematic for practical use △: Ink bleeds or partially flows ×: Evaluation of ink completely flowing down Table 1 shows the results.
[0043]
[Table 1]

[0044]
<Evaluation of results>
(1) As shown in Table 1, the ink jet recording material having the coating based on the water-proofing agent of the present invention used in Examples 1 and 2 has good results in both water resistance and light resistance.
(2) In Comparative Example 1, a cationic polymer containing no monomer unit having a component (b) having an ultraviolet absorbing structure and / or a monomer unit having a photostable structure was used, and the water resistance was good. However, the light resistance was insufficient.
(3) In Comparative Example 2, the polymer was insoluble in water and the coating film was uneven. Further, the light resistance is good, but the water resistance is poor.
[0045]
【The invention's effect】
As described above, the present invention can provide an ink jet waterproofing agent and an ink jet recording material having excellent water resistance and light resistance.

Claims (5)

(A) a monomer unit having a plurality of cationic groups (hereinafter referred to as “cationic monomer unit”), and (b) a monomer unit having an ultraviolet absorbing structure (hereinafter referred to as “ultraviolet absorbing monomer unit”) and / or A water-resistant agent for an ink jet recording material comprising a cationic polymer having a monomer unit having a light-stable structure (hereinafter, referred to as a “light-stable monomer unit”) as a constituent unit. The water resistant agent for an ink jet recording material according to claim 1, wherein the cationic monomer unit (a) is represented by the following formula [I].

However, the symbols in the formula indicate the following contents.
A: an oxygen atom or an imino group ^{R 1:} a hydrogen atom or a methyl group ^R 2, ^{R 5:} an alkylene group having 1 to 12 carbon atoms which may be substituted by a hydroxyl group ^{R 3, R 4, R 6} , R 7 , R ⁹ : independently an alkyl group having 1 to 4 carbon atoms R ⁸ : an alkyl group having 1 to 12 carbon atoms, an aralkyl group, or —CH ₂ COOR ⁹
X ⁻ : counter ion n: integer of 1 to 3 The water-resistant agent for an ink jet recording material according to claim 1 or 2, wherein the ultraviolet absorbing monomer unit (b) is a 2-hydroxybenzophenone residue or a 2'-hydroxyphenylbenzotriazole residue. The water-resistant agent for an ink-jet recording material according to claim 1 or 2, wherein the light-stable monomer unit (b) is a hindered amine residue. An inkjet recording material comprising the waterproofing agent for an inkjet recording material according to any one of claims 1 to 4 on or in a support.