JP4451018B2 - Recording material - Google Patents

Description

（ここで、Ｒ^１は水素原子または置換基を有していてもよい炭素数８以下の炭化水素基を表し、Ｒ^２は酸素を含有する置換基を有していてもよい炭素数１〜４０のアルコキシ基またはアシロキシ基を表わし、ｎは０〜２の整数、ｍは０〜３の整数をそれぞれ表し、ただしｎとｍの合計は３以下であり、Ｘは１価の金属原子を表わす）
【００１６】
Ｒ^１は前述のとおり、水素原子または置換基を有していてもよい炭素数８以下の炭化水素基を表わす。ここで、炭素数８以下の炭化水素基としては、メチル基、エチル基、プロピル基、ブチル基、へキシル基、オクチル基などのアルキル基が好ましく例示され、中でもメチル基およびエチル基が多用される。置換基は酸素、窒素、硫黄などのヘテロ原子を含有していてもよく、この置換基を有する場合の炭化水素基として、メトキシエチル基などが例示される。
Ｒ^２は前述のとおり、酸素を含有する置換基を有していてもよい炭素数１〜４０のアルコキシ基またはアシロキシ基を表わす。その具体例としては、炭素数１〜４０のアルコキシ基またはアシロキシ基としては、メトキシ基、エトキシ基、プロポキシ基、ブトキシ基、ヘキシロキシ基、オクチロキシ基、ラウリロキシ基、オレイロキシ基、アセトキシ基などが例示され、中でもメトキシ基、エトキシ基およびアセトキシ基が多用される。
Ｘは１価の金属原子を表わし、その具体例として、ナトリウム、カリウムなどのアルカリ金属が好ましく例示される。
【００１７】
シリル変性ＰＶＡに含まれるシリル基の含有量は、重合体中の全単量体単位のモル数を基準として０．０１〜２モル％であり、好ましくは０．０３〜１．８モル％であり、より好ましくは０．０５〜１．５モル％である。シリル基の含有量が０．０１モル％よりも小さい場合には、シリル基を導入することによる性能の向上効果が小さいかまたはほとんど向上効果が見られず、２モル％よりも大きい場合には、基材に塗布する際の塗工液の粘度が高くなり過ぎるか、または塗工液の安定性が低下することがある。
【００１８】
上記のシリル変性ＰＶＡにおいて、シリル基はＰＶＡの側鎖または末端に存在する。該シリル基はＰＶＡの側鎖または末端に直接結合していても、またはビニルエステル系重合体のけん化時に切断されない炭化水素基やオキシアルキレン基などの連結基を介して結合していてもよい。
【００１９】
上記のシリル変性ＰＶＡは公知の種々の方法によって製造することができるが、通常は、上記式で示されるシリル基を有するオレフィン系不飽和単量体、または重合およびけん化反応後に上記式で示されるシリル基を生成し得る置換基を有するオレフィン性不飽和単量体の共存下にビニルエステル系単量体を重合して得られるビニルエステル系共重合体を、上記と同様の方法でけん化することにより得られる。上記式で示されるシリル基において、ナトリウム、カリウムなどのアルカリ金属に代表される金属原子Ｘは、主として、上記したビニルエステル系共重合体をナトリウムアルコキシドや水酸化ナトリウム、水酸化カリウムなどの塩基触媒を用いてけん化する際に導入される。
【００２０】
上記式で示されるシリル基を有するオレフィン系不飽和単量体、または重合およびけん化反応後に上記式で示されるシリル基を生成し得る置換基を有するオレフィン性不飽和単量体の具体例としては、ビニルトリメトキシシラン、ビニルトリ（β−メトキシエトキシ）シラン、アリルトリメトキシシラン、ビニルトリアセトキシシラン、アリルトリアセトキシシラン、ビニルメチルジメトキシシラン、ビニルジメチルメトキシシラン、ビニルメチルジエトキシシラン、ビニルジメチルエトキシシラン、ビニルメチルジアセトキシシラン、ビニルジメチルアセトキシシラン、ビニルイソブチルジメトキシシラン、ビニルトリイソプロポキシシラン、ビニルトリブトキシシラン、ビニルトリヘキシロキシシラン、ビニルメトキシジヘキシロキシシラン、ビニルジメトキシオクチロキシシラン、ビニルメトキシジオクチロキシシラン、ビニルトリオクチロキシシラン、ビニルメトキシジラウリロキシシラン、ビニルジメトキシラウリロキシシラン、ビニルメトキシジオレイロキシシラン、ビニルジメトキシオレイロキシシラン、３−（メタ）アクリルアミド−プロピルトリメトキシシラン、３−（メタ）アクリルアミド−プロピルトリエトキシシラン、３−（メタ）アクリルアミド−プロピルトリ（β−メトキシエトキシ）シラン、２−（メタ）アクリルアミド−２−メチルプロピルトリメトキシシラン、２−（メタ）アクリルアミド−２−メチルエチルトリメトキシシラン、Ｎ−（２−（メタ）アクリルアミド−エチル）−アミノプロピルトリメトキシシラン、３−（メタ）アクリルアミド−プロピルトリアセトキシシラン、２−（メタ）アクリルアミド−エチルトリメトキシシラン、１−（メタ）アクリルアミド−メチルトリメトキシシラン、３−（メタ）アクリルアミド−プロピルメチルジメトキシシラン、３−（メタ）アクリルアミド−プロピルジメチルメトキシシラン、３−（Ｎ−メチル−（メタ）アクリルアミド）−プロピルトリメトキシシラン、３−（（メタ）アクリルアミド−メトキシ）−３−ヒドロキシプロピルトリメトキシシラン、３−（（メタ）アクリルアミド−メトキシ）−プロピルトリメトキシシラン、ジメチル−３−（メタ）アクリルアミド−プロピル−３−（トリメトキシシリル）−プロピルアンモニウムクロライド、ジメチル−２−（メタ）アクリルアミド−２−メチルプロピル−３−（トリメトキシシリル）−プロピルアンモニウムクロライドなどが挙げられる。
【００２１】
シリル変性ＰＶＡはまた、ＰＶＡまたはカルボキシル基もしくは水酸基を含有する変性ポリ酢酸ビニルに、シリル化剤を用いて後変性によりシリル基を導入することによっても得ることができる。この方法は、例えば、シリル化剤と反応しないベンゼン、トルエン、キシレン、ヘキサン、ヘプタン、エーテルまたはアセトンなどといった有機溶媒にシリル化剤を溶解させて、該溶液中に粉末状のＰＶＡまたは上記変性ポリ酢酸ビニルを撹拌下に懸濁させ、常温からシリル化剤の沸点までの範囲の温度条件下でシリル化剤とＰＶＡまたは上記変性ポリ酢酸ビニルを反応させることにより、あるいは更にアルカリ触媒等によって酢酸ビニル単位をけん化することにより行なうことができる。この目的に用いることができるシリル化剤としては、トリメチルクロルシラン、ジメチルジクロルシラン、メチルトリクロルシラン、ビニルトリクロルシラン、ジフェニルジクロルシラン、トリエチルフルオルシラン等のオルガノハロゲンシラン、トリメチルアセトキシシラン、ジメチルジアセトキシシランなどのオルガノシリコンエステル、トリメチルメトキシシラン、ジメチルジメトキシシランなどのオルガノアルコキシシラン、トリメチルシラノール、ジエチルシランジオール等のオルガノシラノール、Ｎ−アミノエチルアミノプロピルトリメトキシシラン等のアミノアルキルシラン、トリメチルシリコンイソシアネート等のオルガノシリコンイソシアネート等が挙げられる。
【００２２】
シリル変性ＰＶＡを得るためのその他の方法としては、例えば、アリルグリシジルエーテルやブタジエンモノオキシドなどのエポキシ基を有する単量体の存在下でビニルエステル系単量体を重合し、得られたエポキシ基を有するビニルエステル系共重合体に、３−（トリメトキシシリル）−プロピルメルカプタンなどの同一分子内にメルカプト基とシリル基を有する化合物を反応させた後、けん化を行う方法が挙げられる。また、３−（トリメトキシシリル）−プロピルメルカプタンなどの同一分子内にメルカプト基とシリル基を有する化合物を連鎖移動剤として用いてビニルエステル系単量体の重合を行い、得られたビニルエステル系重合体をけん化することによってシリル変性ＰＶＡ（この場合に得られるシリル変性ＰＶＡは末端変性物）を得る方法も挙げられるが、これらの方法に限定されるものではない。
【００２３】
本発明の被記録材において、ＰＶＡにα−オレフィン単位および上記式で示されるシリル基の両方を含有させた場合には、被記録材の耐水性などの諸物性が大きく向上する。このような変性ＰＶＡにおいて、α−オレフィン単位の含有量は１〜２０モル％であり、好ましくは１．５〜１８モル％であり、より好ましくは２〜１５モル％であり、シリル基の含有量は０．０１〜２モル％であり、好ましくは０．０３〜１．８モル％であり、より好ましくは０．０５〜１．５モル％である。また、本発明の趣旨を損なわない範囲であれば、本発明の被記録材において用いられるＰＶＡは、ビニルエステル単位およびそのけん化物、α−オレフィン単位、上記式で示されるシリル基を有する単量体単位、ならびに重合およびけん化反応後に上記式で示されるシリル基を生成し得る置換基を有する単量体単位以外に、１種または２種以上のその他の単量体単位を有していても差し支えない。そのような単量体単位としては、炭素数が５以上のα−オレフィン類；アクリル酸、メタクリル酸、クロトン酸、フマル酸、マレイン酸、イタコン酸などの不飽和酸類およびこれらの塩または炭素数１〜１８のモノもしくはジアルキルエステル類；アクリルアミド、炭素数１〜１８のＮ−アルキルアクリルアミド、Ｎ，Ｎ−ジメチルアクリルアミド、ジアセトンアクリルアミド、２−アクリルアミドプロパンスルホン酸およびその塩、アクリルアミドプロピルジメチルアミンおよびその酸塩またはその４級塩などのアクリルアミド類；メタクリルアミド、炭素数１〜１８のＮ−アルキルメタクリルアミド、Ｎ，Ｎ−ジメチルメタクリルアミド、２−メタクリルアミドプロパンスルホン酸およびその塩、メタクリルアミドプロピルジメチルアミンおよびその酸塩またはその４級塩などのメタクリルアミド類；Ｎ−ビニルピロリドン、Ｎ−ビニルホルムアミド、Ｎ−ビニルアセトアミドなどのＮ−ビニルアミド類；アクリロニトリル、メタクリロニトリルなどのシアン化ビニル類；炭素数１〜１８のアルキルビニルエーテル、ヒドロキシアルキルビニルエーテル、アルコキシアルキルビニルエーテルなどのビニルエーテル類；ポリエチレングリコールアリルエーテル、メトキシポリエチレングリコールアリルエーテル、ポリプロピレングリコールアリルエーテル、ポリエチレングリコール−ポリプロピレングリコールアリルエーテル、などのポリ（オキシアルキレン）基を有するアリルエーテル；塩化ビニル、フッ化ビニル、臭化ビニルなどのハロゲン化ビニル類；塩化ビニリデン、フッ化ビニリデンなどのハロゲン化ビニリデン類；酢酸アリル、塩化アリル、アリルアルコール、ジメチルアリルアルコールなどが挙げられるが、これらに限定されるものではない。これらの単量体単位の含有量については、得られる重合体が水溶性である限りにおいては特に制限はないが、通常、重合体中の全単量体単位を基準として１０モル％以下であるのが好ましい。
【００２４】
また、本発明の被記録材に用いられるＰＶＡは、チオール酢酸、メルカプトプロピオン酸、炭素数１８以下のアルキルメルカプタンなどのチオール化合物の存在下でビニルエステル系単量体の重合を行い、得られた重合体をけん化して得られる末端変性物でもよい。
【００２５】
さらには、ＰＶＡにホルムアルデヒド、アセトアルデヒド、ブチルアルデヒドなどのカルボニル基含有化合物を酸触媒の存在下で反応させてアセタール化したものや、ＰＶＡとジケテンとの反応で得られるアセトアセチル基を含有するＰＶＡなど、後反応により変性したＰＶＡを用いても差し支えない。
【００２６】
本発明において前述のＰＶＡを使用するに際し、ＰＶＡを水に溶解するにあたっては、ＰＶＡを水に分散後、場合によっては水酸化ナトリウム等のアルカリ化合物を添加し、撹拌しながら加温することによって均一な水溶液とすることができる。
【００２７】
本発明の被記録材に用いられる無水マレイン酸系重合体（Ｂ）としては、炭素数８以下のα−オレフィンと無水マレイン酸の共重合体、炭素数８以下のアルキルビニルエーテルと無水マレイン酸の共重合体、スチレン／無水マレイン酸共重合体などが挙げられる。これらの無水マレイン酸系重合体の中でも水溶性のものが好ましく、具体的にはメチルビニルエーテル／無水マレイン酸共重合体、エチレン／無水マレイン共重合体、イソブテン／無水マレイン酸共重合体などが好適なものとして挙げられる。これらの無水マレイン酸系重合体は必ずしも単独で使用する必要はなく、必要に応じて２種以上混合して用いることができる。
【００２８】
本発明の被記録材において、ビニルアルコール系重合体（Ａ）および無水マレイン酸系重合体（Ｂ）は重量配合比率（Ｂ）／（Ａ）において０．１／９９．９〜４０／６０で用いられることが必須であり、好適には０．５／９９．５〜３０／７０であり、より好適には１／９９〜２５／７５である。
【００２９】
本発明の被記録材において、ＰＶＡ（Ａ）は通常単独で使用されるが、場合によっては他の水溶性または水分散性樹脂と併用することもできる。ＰＶＡ（Ａ）と併用することができる他の水溶性または水分散性樹脂としては、アルブミン、ゼラチン、カゼイン、でんぷん、カチオン化でんぷん、アラビヤゴム、メチルセルロース、ヒドロキシエチルセルロース等のセルロース誘導体、ポリアミド樹脂、メラミン樹脂、ポリ（メタ）アクリルアミド、ポリビニルピロリドン等のノニオン性水溶性樹脂、カルボキシメチルセルロース（ＣＭＣ）、ポリ（メタ）アクリル酸ナトリウム、アルギン酸ナトリウム、水溶性ポリエステル等のアニオン性水溶性樹脂、スチレン−ブタジエン系共重合体ラテックス（ＳＢＲ）、ニトリルゴムラテックス（ＮＢＲ）、酢酸ビニル系エマルジョン、エチレン／酢酸ビニル共重合体エマルジョン、（メタ）アクリルエステル系エマルジョン、塩化ビニル系エマルジョン等の水分散性樹脂等が挙げられるが、必ずしもこれらに限定されない。
【００３０】
また、本発明において、ＰＶＡは微粒子状の合成シリカ、クレー、タルク、ケイソウ土、ゼオライト、炭酸カルシウム、アルミナ、酸化亜鉛、サチンホワイト、有機顔料等の充填材と併用することもできるが、これらに限定されるものではない。
【００３１】
また、本発明の被記録材においては、インクの定着剤としてカチオン性樹脂を併用することもできる。カチオン性樹脂は、水に溶解したときに解離してカチオン性を呈する１級〜３級アミンもしくは４級アンモニウム塩のモノマー、オリゴマーまたはポリマーであり、好ましくはオリゴマーまたはポリマーである。具体的には、ジメチルアミン・エピクロルヒドリン重縮合物、アクリルアミド・ジアリルアミン共重合物、ポリビニルアミン共重合物、ジメチルジアリルアンモニウムクロライド重合物、ポリエチレンイミン等を例示することができるが、これらに限定されるものではない。
【００３２】
本発明の被記録材において用いられる支持基体としては、透明または不透明な従来公知の支持基体がいずれも使用できる。透明な支持基体としては、ポリエステル、ポリスチレン、ポリアミド、ポリ塩化ビニル、ポリメチルメタクリレート、酢酸セルロース、ポリカーボネート、ポリイミド、セロハン、セルロイド等のフイルム、シートまたは透明性の高い紙等が挙げられる。不透明な支持基体としては、一般の紙、顔料コート紙、布、木材、金属板、合成紙、不透明化処理した合成樹脂系フイルムまたはシート等が挙げられる。
【００３３】
支持基体中または表面に、ＰＶＡ（Ａ）および無水マレイン酸系重合体（Ｂ）を含有するインク吸収層を形成させる方法としては、ＰＶＡ（Ａ）および無水マレイン酸系重合体（Ｂ）の水溶液、またはＰＶＡ（Ａ）および無水マレイン酸系重合体（Ｂ）と他の水溶性樹脂または水分散性樹脂および／または充填材との混合物からなる水溶液または水分散液を、サイズプレス、エアーナイフコーター、ロールコーター、バーコーター、ブレードコーター、カーテンコーター、キャストコーター等を用いる通常のコーティング方法によって支持基体中に含浸させるか、支持基体の上表面または上表面と下表面との両表面上にコート層を形成させる等の方法を採用することができる。また、支持基体が紙である場合には、紙の抄紙時に上記水溶液あるいは水分散液を内添する方法を採用することもできる。なお、本発明の被記録材において、支持基体中または表面にインク吸収層を有するとは、支持基体中および支持基体表面のいずれかにインク吸収層を有する場合と、支持基体中および基体表面の両方にインク吸収層を有する場合の両方の態様を意味する。
【００３４】
本発明において、被記録材中のＰＶＡ（Ａ）と無水マレイン酸系重合体（Ｂ）の合計含有量について特に制限はないが、通常０．１〜２００ｇ／ｍ²の範囲で用いられるのが好適であり、中でも１〜１００ｇ／ｍ²の範囲内で用いられる場合が多い。
【００３５】
【実施例】
以下、実施例および比較例を挙げて本発明をさらに具体的に説明するが、本発明はこれらによって何ら限定されるものではない。ここで、実施例１〜５、１０、１１、１３、１５および１６は、分子内にシリル基を有さない変性ＰＶＡを用いて得られた被記録材に関するものであり、参考のために記載するものである。本発明の実施例は、実施例６〜９、１２、１４および１７〜１９である。以下の実施例および比較例において、「部」および「％」は特に断りのない限りそれぞれ「重量部」および「重量％」を意味する。以下の実施例および比較例では、インクジェット被記録材の製造に用いたＰＶＡを以下のようにして合成した。
【００３６】
（１）エチレン単位を含有するＰＶＡ（ＰＶＡ−３）の合成
合成例１
撹拌機、窒素導入口、エチレン導入口および開始剤添加口を備えた５０Ｌ加圧反応槽に酢酸ビニル単量体２２．０ｋｇ、メタノール８．０ｋｇを仕込み、６０℃に昇温した後３０分間窒素バブリングにより系中を窒素ガスで置換した。次いで、反応槽の圧力が０．５８ＭＰａとなるようにエチレンを導入仕込みした。上記の反応槽の内温を６０℃に調整した後、開始剤として２，２’−アゾビス（ジメチルバレロニトリル）０．９ｇを添加して重合を開始した。重合中はエチレンを導入して反応槽の圧力を０．５８ＭＰａに、重合温度を６０℃に維持し、４時間後に重合率が４０％に達したところで冷却して重合を停止した。反応槽を開放して脱エチレンを行った後、窒素ガスをバブリングして脱エチレンを完全に行った。続いて、３０℃、減圧下でメタノールを時々添加しながら未反応の酢酸ビニル単量体の除去を行い、エチレン−酢酸ビニル共重合体のメタノール溶液を得た。次に、濃度３５％に調整したエチレン−酢酸ビニル共重合体のメタノール溶液に、アルカリモル比（ＮａＯＨのモル数／重合体中の酢酸ビニル単位のモル数）が０．０８となるようにＮａＯＨメタノール溶液（濃度１０％）を添加してけん化を行い、エチレン変性ＰＶＡ（ＰＶＡ−３）を得た。ＰＶＡ−３のけん化度をＪＩＳ Ｋ６７２６に従って測定したところ、けん化度は９８．５モル％であった。重合後、未反応酢酸ビニル単量体を除去して得られたエチレン−酢酸ビニル共重合体のメタノール溶液をｎ−ヘキサンに沈殿、アセトンで溶解する再沈精製を３回行った後、６０℃で減圧乾燥して精製されたエチレン−酢酸ビニル共重合体を得た。このエチレン−酢酸ビニル共重合体精製物について、^１Ｈ ＮＭＲ測定から求めたエチレン変性量は７モル％であった。上記のエチレン−酢酸ビニル共重合体のメタノール溶液をアルカリモル比０．２でけん化した後、メタノールソックスレー抽出を３日間実施し、次いで乾燥して精製ＰＶＡを得た。該ＰＶＡの平均重合度をＪＩＳ Ｋ６７２６に準じて測定したところ１０００であった。
【００３７】
合成例２、合成例３および合成例８
酢酸ビニル単量体、メタノール量および重合時のエチレン圧力などの各条件を表１に示すように変更した以外は合成例１と同様にしてエチレン−酢酸ビニル共重合体を得た。次いで、けん化時の重合体濃度やアルカリ使用量（アルカリモル比）を表２に示すように変更した以外は合成例１と同様にして、エチレン変性ＰＶＡ（ＰＶＡ−４、ＰＶＡ−５およびＰＶＡ−１１）を得た。
【００３８】
（２）シリル基を有するＰＶＡ（ＰＶＡ−６）の合成
合成例４
撹拌機、還流冷却管、窒素導入管および温度計を取り付けた５０Ｌの反応器に、酢酸ビニル単量体２１．０ｋｇ、ビニルトリメトキシシラン９０ｇおよびメタノール９．０ｋｇを仕込み、窒素ガスを３０分バブリングして脱気した。反応器の昇温を開始し、内温が６０℃となったところで、２，２’−アゾビス（イソブチロニトリル）９．１ｇを添加して重合を開始し、４時間後に重合率が５０％に達したところで冷却して重合を停止した。続いて、３０℃、減圧下でメタノールを時々添加しながら未反応の酢酸ビニル単量体の除去を行い、酢酸ビニル共重合体のメタノール溶液を得た。次に、濃度２５％に調整した酢酸ビニル共重合体のメタノール溶液に、アルカリモル比０．０３のＮａＯＨメタノール溶液（濃度１０％）を添加してけん化を行い、シリル基を有するＰＶＡ（ＰＶＡ−６）を得た。ＰＶＡ−６のけん化度をＪＩＳ Ｋ６７２６に従って測定した結果、けん化度は９８．０モル％であった。重合後、未反応酢酸ビニル単量体を除去して得られた酢酸ビニル共重合体のメタノール溶液をｎ−ヘキサンに沈殿、アセトンで溶解する再沈精製を３回行った後、６０℃で減圧乾燥して精製された酢酸ビニル共重合体を得た。この酢酸ビニル共重合体精製物について、^１Ｈ ＮＭＲ測定から求めたビニルトリメトキシシラン変性量は０．２５モル％であった。上記の酢酸ビニル共重合体のメタノール溶液をアルカリモル比０．２でけん化した後、メタノールソックスレー抽出を３日間実施し、次いで乾燥して変性ＰＶＡ精製物を得た。該変性ＰＶＡの平均重合度をＪＩＳ Ｋ６７２６に準じて測定したところ１７５０であった。
【００３９】
合成例５、合成例６、合成例９および合成例１０
酢酸ビニル単量体、メタノール、ビニルトリメトキシシランおよび開始剤の量を表１に示すように変更した以外は合成例４と同様にして酢酸ビニル共重合体を得た。次いで、けん化時の重合体濃度やアルカリ使用量（アルカリモル比）を表２に示すように変更した以外は合成例４と同様にして、シリル基を有するＰＶＡ（ＰＶＡ−７、ＰＶＡ−８、ＰＶＡ−１２およびＰＶＡ−１３）を得た。
【００４０】
（３）エチレン単位およびシリル基を有するＰＶＡ（ＰＶＡ−９）の合成
合成例７
撹拌機、窒素導入口、エチレン導入口および開始剤添加口を備えた５０Ｌ加圧反応槽に酢酸ビニル単量体２４．８ｋｇ、ビニルトリメトキシシラン４０ｇおよびメタノール５．２ｋｇを仕込み、６０℃に昇温した後３０分間窒素バブリングにより系中を窒素ガスで置換した。次いで、反応槽の圧力が０．４６ＭＰａとなるようにエチレンを導入仕込みした。反応槽の内温を６０℃に調整した後、開始剤として２，２’−アゾビス（ジメチルバレロニトリル）０．８ｇを添加して重合を開始した。重合中はエチレンを導入して反応槽の圧力を０．４６ＭＰａに、重合温度を６０℃に維持し、４時間後に重合率が４０％に達したところで冷却して重合を停止した。反応槽を開放して脱エチレンを行った後、窒素ガスをバブリングして脱エチレンを完全に行った。続いて、３０℃、減圧下でメタノールを時々添加しながら未反応の酢酸ビニル単量体の除去を行い、エチレン−酢酸ビニル共重合体のメタノール溶液を得た。次に、濃度２５％に調整したエチレン−酢酸ビニル共重合体のメタノール溶液に、アルカリモル比０．０５のＮａＯＨメタノール溶液（濃度１０％）を添加してけん化を行い、エチレン単位およびシリル基を有するＰＶＡ（ＰＶＡ−９）を得た。ＰＶＡ−９のけん化度をＪＩＳ Ｋ６７２６に従って測定したところ、けん化度は９８．５モル％であった。重合後、未反応酢酸ビニル単量体を除去して得られたエチレン−酢酸ビニル共重合体のメタノール溶液をｎ−ヘキサンに沈殿、アセトンで溶解する再沈精製を３回行った後、６０℃で減圧乾燥して精製されたエチレン−酢酸ビニル共重合体を得た。このエチレン−酢酸ビニル共重合体精製物について、^１Ｈ ＮＭＲ測定から求めたエチレン変性量は５モル％、ビニルトリメトキシシラン変性量は０．２モル％であった。上記のエチレン−酢酸ビニル共重合体のメタノール溶液をアルカリモル比０．２でけん化した後、メタノールソックスレー抽出を３日間実施し、次いで乾燥して変性ＰＶＡ精製物を得た。該変性ＰＶＡの平均重合度をＪＩＳ Ｋ６７２６に準じて測定したところ１５５０であった。
【００４１】
【表１】

【００４２】
【表２】

【００４３】
また、以下の実施例および比較例において用いたＰＶＡについての詳細を表３に示す。
【００４４】
【表３】

【００４５】
実施例および比較例において、インクジェット被記録材の諸物性は以下のようにして評価した。
（１）インクジェット記録方法
吐出オリフィス径６０μｍの高オンディマインド型インクジェット記録ヘッドを有する記録装置を用い、下記４色のインクを用いてカラーインクジェット記録を行い、記録特性の評価を行った。
イエローインク（組成）
Ｃ.Ｉ.アシッドイエロー２．３ ２部
ジエチレングリコール ３０部
水 ７０部
マゼンタインク（組成）
Ｃ.Ｉ.アシッドレッド３２ ２部
ジエチレングリコール ３０部
水 ７０部
シアンインク（組成）
Ｃ.Ｉ.ダイレクトブルー８６ ２部
ジエチレングリコール ３０部
水 ７０部
ブラックインク（組成）
Ｃ.Ｉ.ダイレクトブラック１９ ２部
ジエチレングリコール ３０部
水 ７０部
【００４６】
（２）インク吸収性（インク吸収速度）
インクジェット記録後、一定時間ごとに被記録材上の印字を指でこすり、印字部分が変化しなくなるまで（印字部が乱れなくなったときまで）に要した時間を測定した。時間が短いほどインク吸収速度が大であることを示す。
（３）にじみ度
印字ドットの直径を実体顕微鏡で測定し、インク滴の何倍になったかを測定した。倍率が低いほど、にじみが少ないことを示し、また画像の鮮明度がより優れることを示す。
（４）透明度
インクジェット用被記録材の非印字部分の可視光線透過率（％）を、５００ｎｍの波長の可視光線を用いて分光光度計で測定した。この透過率を透明度とする。透過率が大である程、透明性が高いことを示す。
（５）耐水性
インクジェット用被記録材を２０℃の蒸留水中に１分間浸漬した後、シート表面を指でこすり、次の基準により評価した。
○：インク吸収層の脱落はほとんどない。 また指をシート表面から離したとき、指の糸引きが見られない（耐スティッキング性が良好）。
△：インク吸収層の脱落が少しある。また指への糸引きが２〜３本見られる（耐スティッキング性がやや悪い）。
×：インク吸収層の脱落がかなり激しい。また指全面にからみつき、多数の糸引きが見られる（耐スティッキング性が悪い）。
【００４７】
実施例１（マットタイプのインク吸収層の作製）
重合度１０００、けん化度９８．５モル％のＰＶＡ（Ａ）（（株）クラレ製「ＰＶＡ−１１０」）（ＰＶＡ−１）の１０％水溶液（ｂ）を作製した。シリカ粉末（水沢化学（株）製「ミズカシルＰ−７８Ｄ」）１００部に水４００部を加えて十分分散させながら、水溶液（ｂ）２００部をゆっくり室温で加えて、ＰＶＡのシリカ分散水溶液を作製した。メチルビニルエーテル／無水マレイン酸交互共重合体（ＩＳＰ社製「ＧＡＮＴＲＥＺ ＡＮ−１１９」）（Ｂ）の１０％水溶液１０．５部をＰＶＡのシリカ分散水溶液に室温で撹拌しながらゆっくり加え、さらに適当量の蒸留水を加えて固形濃度１６％塗工液を調製した｛重量配合比率：（Ｂ）／（Ａ）＝５／９５｝。この塗工液を３０℃で２週間放置したところ、塗工液の粘度はほとんど変化しておらず粘度安定性は良好であった。次に、厚さ５０μｍ、透明度９５％のポリエステルフィルム上に、上記の塗工液を、乾燥後の塗布量（全固形分）が１５ｇ／ｍ² ｛ＰＶＡ（Ａ）とメチルビニルエーテル／無水マレイン酸交互共重合体（Ｂ）の合計固形分で２．６ｇ／ｍ²｝となるよう手塗りで塗布して、インク吸収層を形成させ、熱風乾燥機にて１００℃、３分間乾燥してインクジェット用被記録材を得た。このシートについて評価した結果を表４に示す。
【００４８】
実施例２
実施例１において、ＰＶＡとして、重合度１７００、けん化度９８．５モル％のＰＶＡ（Ａ）（（株）クラレ製「ＰＶＡ−１１７」）（ＰＶＡ−２）を用いた以外は実施例１と同様にして塗工液を調製し、被記録材を製造した。得られた被記録材について評価した結果を表４に示す。
【００４９】
実施例３〜１２
実施例１において、ＰＶＡの種類および／またはメチルビニルエーテル／無水マレイン酸交互共重合体の１０％水溶液の添加量を表４に示した内容に変更した以外は実施例１と同様にして塗工液を調製し、被記録材を製造した。得られた被記録材について評価した結果を表４に示す。
【００５０】
実施例１３および実施例１４
実施例１において、メチルビニルエーテル／無水マレイン酸交互共重合体の代わりに市販のエチレン／無水マレイン酸交互共重合体（Ａｌｄｒｉｃｈ）を用い、ＰＶＡの種類を表４に示した内容のものに変更した以外は実施例１と同様にして塗工液を調製し、被記録材を製造した。得られた被記録材について評価した結果を表４に示す。
【００５１】
実施例１５（グロスタイプのインク吸収層の作製）
重合度２４００、けん化度８７．０モル％のＰＶＡ（Ａ）（（株）クラレ製「ＰＶＡ−２２４」）（ＰＶＡ−１０）の１０％水溶液を作成した。コロイダルシリカ（日産化学（株）製「スノーテックス３０」）１００部に上記のＰＶＡ水溶液３０部をゆっくり室温で加えて、ＰＶＡのコロイダルシリカ分散水溶液を作成した。メチルビニルエーテル／無水マレイン酸交互共重合体（ＩＳＰ社製「ＧＡＮＴＲＥＺ ＡＮ−１１９」）（Ｂ）の１０％溶液１．６部をＰＶＡのコロイダルシリカ分散水溶液に室温で撹拌しながらゆっくり加え、さらに適当量の蒸留水を加えて固形濃度２０％塗工液を調製した｛重量配合比率：（Ｂ）／（Ａ）＝５／９５｝。次に、厚さ５０μｍ、透明度９５％のポリエステルフィルム上に、上記の塗工液を、乾燥後の塗布量が１５ｇ／ｍ² となるよう手塗りし、熱風乾燥機にて１００℃、３分間乾燥してインクジェット用被記録材を得た。このシートについて評価した結果を表４に示す。
【００５２】
実施例１６〜１８
実施例１５において、ＰＶＡの種類および／またはメチルビニルエーテル／無水マレイン酸交互共重合体の１０％水溶液の添加量を表４に示した内容に変更した以外は実施例１３と同様にして塗工液を調製し、被記録材を製造した。得られた被記録材について評価した結果を表４に示す。
【００５３】
比較例１〜４
実施例１において、ＰＶＡの種類および／またはメチルビニルエーテル／無水マレイン酸交互共重合体の１０％水溶液の添加量を表４に示した内容に変更した以外は実施例１と同様にして塗工液を調製し、被記録材を製造した。得られた被記録材について評価した結果を表４に示す。
【００５４】
比較例５〜７
実施例１３において、ＰＶＡの種類およびエチレン／無水マレイン酸交互共重合体の１０％水溶液の添加量を表４に示した内容に変更した以外は実施例１３と同様にして塗工液を調製し、被記録材を製造した。得られた被記録材について評価した結果を表４に示す。
【００５５】
実施例１９
支持基体としてポリエチレンラミネート（１５μｍ）を施した基材を用いた以外は、実施例１と同様にして被記録材を製造した。得られた被記録材について評価した結果を表４に示す。
【００５６】
【表４】

【００５７】
【発明の効果】
本発明の被記録材は、耐水性および耐スティッキング性に優れ、また印字のにじみ度が小さく記録画像の鮮明性に優れ、さらにまたインク吸収性に優れている。[0001]
BACKGROUND OF THE INVENTION
The present invention is not only excellent in water resistance and anti-sticking property, but also has a low print bleeding, excellent recorded image sharpness, and excellent ink absorption. About.
[0002]
[Prior art]
Examples of writing instruments that use water-based inks such as water-soluble dye inks and pigment-dispersible inks as recording liquids include fountain pens, water-based ballpoint pens, water-based sign pens, ceramic pens, fluorescent pens, and pen plotters using these. Recently, an ink jet recording system in which a droplet of water-based ink is ejected onto a recording material and characters and images are attached is recorded.
[0003]
The inkjet recording system is being applied to facsimiles, various printers, and the like for reasons such as low noise, easy colorization, and high-speed recording.
Conventionally, ordinary paper has been used as the recording material used in the ink jet recording system. However, with recent improvements in the performance of ink jet recording machines such as higher speed recording and multicolor printing, However, more advanced characteristics have been demanded. The required characteristics are: first, the ink absorption speed is large, second, the ink dot diameter is not larger than necessary, third, the shape of the ink dot is close to a perfect circle, and fourth, handling And good storage properties. In order to satisfy these required characteristics, various studies have been made such as using a vinyl alcohol polymer, polyacrylamide, etc. as an ink absorptive material, but improving the ink absorptivity leads to a decrease in water resistance. At present, there are problems such as dropping of the ink absorbing layer when in contact with water, and bleeding of the print.
[0004]
2. Description of the Related Art In recent years, inkjet recording materials for wide format have attracted attention as an application that uses the inkjet recording method on-mind, and in particular, advertising applications used for outdoor postings have attracted attention. In such outdoor applications, an overcoat layer in which polyethylene is laminated is often provided on the surface of a recording material so that it can withstand exposure to wind and rain. However, providing an overcoat layer on the surface of the recording material leads to an increase in cost, and furthermore, when recovering the recording material as used paper, it is necessary to separate the paper and the overcoat layer, which is not suitable for recovery. Therefore, it has been desired to develop an ink jet recording material excellent in water resistance without providing an overcoat layer.
[0005]
[Problems to be solved by the invention]
The object of the present invention is not only excellent in water resistance and sticking resistance, but also in a recording material, particularly ink jet, which has low printing bleeding, excellent recorded image sharpness, and excellent ink absorption. It is to provide a recording material.
Furthermore, an object of the present invention is to provide an ink-jet recording material having a water-based ink absorbing layer on a base material and excellent in water resistance suitable for wide formats such as outdoor advertisements, and optical devices such as slides and OHPs. Accordingly, an object of the present invention is to provide a recording material for projecting a recorded image onto a screen or the like, or an ink jet recording material excellent in transparency for transmitted light observation such as a color display.
[0006]
[Means for Solving the Problems]
As a result of intensive studies, the present inventors have found that the above problem is Support substrate surface In addition, Modified polyvinyl alcohol having a silyl group in the molecule (A) and maleic anhydride polymer (B) Contains , Polyvinyl alcohol This is achieved by a recording material having an ink absorbing layer in which the weight blending ratio (B) / (A) of (A) and the maleic anhydride polymer (B) is 0.1 / 99.9 to 40/60. As a result, the present invention has been completed.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
The recording material of the present invention will be described in more detail below.
[0008]
The degree of polymerization of the vinyl alcohol polymer (hereinafter sometimes abbreviated as PVA) used for the recording material of the present invention is not particularly limited, but is usually 100 to 10,000, preferably 150 to 8,000, More preferably, it is 200-6000. Here, the degree of polymerization of PVA is measured according to JIS K6726, and is determined from the intrinsic viscosity measured in water at 30 ° C. using re-saponified and purified PVA. When the degree of polymerization of PVA is less than 100, the water resistance and sticking resistance of the recording material may be lowered. If the degree of polymerization is greater than 10,000, the viscosity of the coating solution may increase when applied to the substrate, or the stability of the coating solution may be impaired.
[0009]
Although there is no restriction | limiting in particular also about the saponification degree of PVA, Usually, it is 65-99.99 mol%, Preferably it is 75-99.95 mol%, More preferably, it is 80-99.9 mol%. Here, the saponification degree of PVA is measured according to JIS K6726. When the saponification degree of PVA is less than 65 mol%, the water resistance of the recording material may be lowered. Moreover, industrial production of PVA having a saponification degree of PVA larger than 99.99 mol% is difficult.
[0010]
PVA can generally be produced by saponifying a vinyl ester polymer obtained by polymerizing a vinyl ester monomer. Examples of vinyl ester monomers include vinyl formate, vinyl acetate, vinyl propionate, vinyl valelate, vinyl caproate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl pivalate, vinyl versatate, etc. Vinyl acetate is preferably used. As the polymerization method of the vinyl ester monomer, known polymerization methods such as solution polymerization method, bulk polymerization method, suspension polymerization method, emulsion polymerization method and the like can be used. Usually, alcohol such as methanol is used as a solvent. The solution polymerization method used is used. There is no restriction | limiting in particular about superposition | polymerization temperature, Usually, it can select arbitrarily from the range of 0 to 150 degreeC.
[0011]
As a method for saponifying a vinyl ester polymer, a known method using an acid or base catalyst can be used, but sodium alkoxide or sodium hydroxide is usually used in an alcohol solvent (which may contain a small amount of water). A saponification method using a base catalyst such as potassium hydroxide is used.
[0012]
In the recording material of the present invention, when the PVA contains an α-olefin unit having 4 or less carbon atoms, the water resistance of the recording material is remarkably improved. Therefore, the modified PVA containing such an α-olefin unit. Use of is recommended. The content of α-olefin units contained in the modified PVA is 1 to 20 mol%, preferably 1.5 to 18 mol%, based on the number of moles of all monomer units in the polymer, and more Preferably it is 2-15 mol%. When the content of α-olefin units is less than 1 mol%, the effect of modification is insufficient. When the content of the α-olefin unit exceeds 20 mol%, the stability of the coating liquid when the recording material is applied to the substrate may be lowered.
[0013]
Modified PVA containing an α-olefin unit can be produced by saponifying an α-olefin-vinyl ester copolymer obtained by polymerizing a vinyl ester monomer in the presence of an α-olefin. The types of vinyl ester monomers that can be used, the polymerization method of vinyl ester monomers and the saponification method of vinyl ester polymers are the same vinyl ester polymers, polymerization methods and saponification methods as described above. Is possible.
[0014]
In the recording material of the present invention, when the PVA contains a silyl group represented by the following formula, the water resistance and other physical properties of the recording material are greatly improved. Therefore, the PVA having such a silyl group is used. The use of (hereinafter sometimes abbreviated as silyl-modified PVA) is preferred.
[0015]
[Chemical 1]

(Where R ¹ Represents a hydrogen atom or a hydrocarbon group having 8 or less carbon atoms which may have a substituent, R ² Represents an alkoxy group having 1 to 40 carbon atoms or an acyloxy group which may have a substituent containing oxygen, n represents an integer of 0 to 2, and m represents an integer of 0 to 3, respectively. The total of m is 3 or less, and X represents a monovalent metal atom)
[0016]
R ¹ As described above, represents a hydrogen atom or a hydrocarbon group having 8 or less carbon atoms which may have a substituent. Here, examples of the hydrocarbon group having 8 or less carbon atoms include alkyl groups such as a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, and an octyl group. Among them, a methyl group and an ethyl group are frequently used. The The substituent may contain a heteroatom such as oxygen, nitrogen and sulfur, and examples of the hydrocarbon group having this substituent include a methoxyethyl group.
R ² As described above, represents an alkoxy group having 1 to 40 carbon atoms or an acyloxy group which may have a substituent containing oxygen. Specific examples of the alkoxy group or acyloxy group having 1 to 40 carbon atoms include methoxy group, ethoxy group, propoxy group, butoxy group, hexyloxy group, octyloxy group, lauryloxy group, oleyloxy group, and acetoxy group. Of these, methoxy, ethoxy and acetoxy groups are frequently used.
X represents a monovalent metal atom, and specific examples thereof are preferably alkali metals such as sodium and potassium.
[0017]
The content of the silyl group contained in the silyl-modified PVA is 0.01 to 2 mol%, preferably 0.03 to 1.8 mol%, based on the number of moles of all monomer units in the polymer. Yes, more preferably 0.05 to 1.5 mol%. When the silyl group content is less than 0.01 mol%, the performance improvement effect by introducing the silyl group is small or almost no improvement effect is seen, and when the content is greater than 2 mol% The viscosity of the coating liquid when applied to the substrate may become too high, or the stability of the coating liquid may be reduced.
[0018]
In the above silyl-modified PVA, the silyl group is present in the side chain or terminal of the PVA. The silyl group may be directly bonded to the side chain or terminal of PVA, or may be bonded via a linking group such as a hydrocarbon group or an oxyalkylene group that is not cleaved during saponification of the vinyl ester polymer.
[0019]
The above silyl-modified PVA can be produced by various known methods, but is usually represented by the above formula after the olefinic unsaturated monomer having a silyl group represented by the above formula, or after polymerization and saponification reaction. Saponifying a vinyl ester copolymer obtained by polymerizing a vinyl ester monomer in the presence of an olefinically unsaturated monomer having a substituent capable of generating a silyl group in the same manner as described above. Is obtained. In the silyl group represented by the above formula, the metal atom X typified by alkali metal such as sodium or potassium is mainly composed of the above vinyl ester copolymer as a base catalyst such as sodium alkoxide, sodium hydroxide or potassium hydroxide. It is introduced when saponifying using.
[0020]
Specific examples of the olefinically unsaturated monomer having a silyl group represented by the above formula or the olefinically unsaturated monomer having a substituent capable of generating a silyl group represented by the above formula after polymerization and saponification reaction , Vinyltrimethoxysilane, vinyltri (β-methoxyethoxy) silane, allyltrimethoxysilane, vinyltriacetoxysilane, allyltriacetoxysilane, vinylmethyldimethoxysilane, vinyldimethylmethoxysilane, vinylmethyldiethoxysilane, vinyldimethylethoxysilane , Vinylmethyldiacetoxysilane, vinyldimethylacetoxysilane, vinylisobutyldimethoxysilane, vinyltriisopropoxysilane, vinyltributoxysilane, vinyltrihexyloxysilane, vinylmethoxydihexyloxysilane , Vinyldimethoxyoctyloxysilane, vinylmethoxydioctyloxysilane, vinyltrioctyloxysilane, vinylmethoxydilauryloxysilane, vinyldimethoxylauryloxysilane, vinylmethoxydioleoyloxysilane, vinyldimethoxyoleyloxysilane, 3- ( Meth) acrylamide-propyltrimethoxysilane, 3- (meth) acrylamide-propyltriethoxysilane, 3- (meth) acrylamide-propyltri (β-methoxyethoxy) silane, 2- (meth) acrylamide-2-methylpropyltri Methoxysilane, 2- (meth) acrylamide-2-methylethyltrimethoxysilane, N- (2- (meth) acrylamide-ethyl) -aminopropyltrimethoxysilane, 3- (meth) acrylami -Propyltriacetoxysilane, 2- (meth) acrylamide-ethyltrimethoxysilane, 1- (meth) acrylamide-methyltrimethoxysilane, 3- (meth) acrylamide-propylmethyldimethoxysilane, 3- (meth) acrylamide-propyl Dimethylmethoxysilane, 3- (N-methyl- (meth) acrylamide) -propyltrimethoxysilane, 3-((meth) acrylamide-methoxy) -3-hydroxypropyltrimethoxysilane, 3-((meth) acrylamide-methoxy ) -Propyltrimethoxysilane, dimethyl-3- (meth) acrylamide-propyl-3- (trimethoxysilyl) -propylammonium chloride, dimethyl-2- (meth) acrylamide-2-methylpropyl-3- (trime Kishishiriru) - and propyl ammonium chloride.
[0021]
Silyl-modified PVA can also be obtained by introducing silyl groups into PVA or modified polyvinyl acetate containing carboxyl groups or hydroxyl groups by post-modification using a silylating agent. In this method, for example, a silylating agent is dissolved in an organic solvent such as benzene, toluene, xylene, hexane, heptane, ether, or acetone that does not react with the silylating agent, and the powdered PVA or the modified polysiloxane is dissolved in the solution. Vinyl acetate is suspended under stirring and reacted with silylating agent and PVA or the modified polyvinyl acetate under temperature conditions ranging from room temperature to the boiling point of the silylating agent, or further with an alkali catalyst or the like. This can be done by saponifying the unit. Silylating agents that can be used for this purpose include trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, vinyltrichlorosilane, diphenyldichlorosilane, triethylfluorosilane, and other organohalogen silanes, trimethylacetoxysilane, dimethyl Organosilicon esters such as diacetoxysilane, organoalkoxysilanes such as trimethylmethoxysilane and dimethyldimethoxysilane, organosilanols such as trimethylsilanol and diethylsilanediol, aminoalkylsilanes such as N-aminoethylaminopropyltrimethoxysilane, and trimethylsilicon And organosilicon isocyanates such as isocyanate.
[0022]
As another method for obtaining silyl-modified PVA, for example, a vinyl ester monomer is polymerized in the presence of a monomer having an epoxy group such as allyl glycidyl ether or butadiene monoxide, and the resulting epoxy group is obtained. Examples thereof include a method in which a vinyl ester copolymer having a saponification is reacted with a compound having a mercapto group and a silyl group in the same molecule, such as 3- (trimethoxysilyl) -propyl mercaptan. Further, a vinyl ester monomer obtained by polymerizing a vinyl ester monomer using a compound having a mercapto group and a silyl group in the same molecule such as 3- (trimethoxysilyl) -propyl mercaptan as a chain transfer agent was obtained. Although the method of obtaining silyl modification | denaturation PVA (The silyl modification | denaturation PVA obtained in this case is a terminal modification | denaturation thing) by saponifying a polymer is also mentioned, It is not limited to these methods.
[0023]
In the recording material of the present invention, when the PVA contains both the α-olefin unit and the silyl group represented by the above formula, various physical properties such as water resistance of the recording material are greatly improved. In such modified PVA, the content of α-olefin units is 1 to 20 mol%, preferably 1.5 to 18 mol%, more preferably 2 to 15 mol%, and the inclusion of silyl groups The amount is from 0.01 to 2 mol%, preferably from 0.03 to 1.8 mol%, more preferably from 0.05 to 1.5 mol%. In addition, as long as the gist of the present invention is not impaired, the PVA used in the recording material of the present invention is a monomer having a vinyl ester unit and a saponified product thereof, an α-olefin unit, and a silyl group represented by the above formula. In addition to the monomer unit and the monomer unit having a substituent capable of generating the silyl group represented by the above formula after polymerization and saponification reaction, it may have one or more other monomer units. There is no problem. Examples of such monomer units include α-olefins having 5 or more carbon atoms; unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, fumaric acid, maleic acid, itaconic acid, and salts or carbon numbers thereof. 1-18 mono- or dialkyl esters; acrylamide, C1-C18 N-alkyl acrylamide, N, N-dimethyl acrylamide, diacetone acrylamide, 2-acrylamidopropane sulfonic acid and salts thereof, acrylamidopropyldimethylamine and its Acrylates such as acid salts or quaternary salts thereof; methacrylamide, N-alkylmethacrylamide having 1 to 18 carbon atoms, N, N-dimethylmethacrylamide, 2-methacrylamideamidesulfonic acid and salts thereof, methacrylamidepropyldimethyl Ami And methacrylamides such as acid salts or quaternary salts thereof; N-vinylamides such as N-vinylpyrrolidone, N-vinylformamide, and N-vinylacetamide; vinyl cyanides such as acrylonitrile and methacrylonitrile; Vinyl ethers such as 1-18 alkyl vinyl ethers, hydroxyalkyl vinyl ethers, alkoxyalkyl vinyl ethers; poly (oxyalkylenes) such as polyethylene glycol allyl ether, methoxy polyethylene glycol allyl ether, polypropylene glycol allyl ether, polyethylene glycol-polypropylene glycol allyl ether Allyl ethers having a group; vinyl halides such as vinyl chloride, vinyl fluoride and vinyl bromide; vinylidene chloride, fluorine Examples thereof include, but are not limited to, vinylidene halides such as vinylidene halide; allyl acetate, allyl chloride, allyl alcohol, dimethylallyl alcohol, and the like. The content of these monomer units is not particularly limited as long as the resulting polymer is water-soluble, but is usually 10 mol% or less based on the total monomer units in the polymer. Is preferred.
[0024]
The PVA used for the recording material of the present invention was obtained by polymerizing a vinyl ester monomer in the presence of a thiol compound such as thiol acetic acid, mercaptopropionic acid, or alkyl mercaptan having 18 or less carbon atoms. It may be a terminally modified product obtained by saponifying a polymer.
[0025]
Furthermore, PVA is acetalized by reacting PVA with a carbonyl group-containing compound such as formaldehyde, acetaldehyde, butyraldehyde in the presence of an acid catalyst, PVA containing an acetoacetyl group obtained by reaction of PVA with diketene, etc. PVA modified by post reaction may be used.
[0026]
When using the above-mentioned PVA in the present invention, in dissolving PVA in water, after dispersing PVA in water, in some cases, an alkali compound such as sodium hydroxide is added, and the mixture is heated with stirring to be uniform. A simple aqueous solution.
[0027]
The maleic anhydride polymer (B) used for the recording material of the present invention is a copolymer of an α-olefin having 8 or less carbon atoms and maleic anhydride, an alkyl vinyl ether having 8 or less carbon atoms and maleic anhydride. Examples thereof include a copolymer and a styrene / maleic anhydride copolymer. Among these maleic anhydride polymers, water-soluble ones are preferable, and specifically, methyl vinyl ether / maleic anhydride copolymer, ethylene / maleic anhydride copolymer, isobutene / maleic anhydride copolymer and the like are preferable. It is mentioned as a thing. These maleic anhydride polymers do not necessarily need to be used alone, and can be used as a mixture of two or more as required.
[0028]
In the recording material of the present invention, the vinyl alcohol polymer (A) and the maleic anhydride polymer (B) are 0.1 / 99.9 to 40/60 in the weight ratio (B) / (A). It is essential to be used, preferably 0.5 / 99.5 to 30/70, and more preferably 1/99 to 25/75.
[0029]
In the recording material of the present invention, PVA (A) is usually used alone, but in some cases, it can be used in combination with other water-soluble or water-dispersible resins. Other water-soluble or water-dispersible resins that can be used in combination with PVA (A) include albumin, gelatin, casein, starch, cationized starch, arabic gum, cellulose derivatives such as methylcellulose, hydroxyethylcellulose, polyamide resins, and melamine resins. Nonionic water-soluble resins such as poly (meth) acrylamide and polyvinylpyrrolidone, anionic water-soluble resins such as carboxymethylcellulose (CMC), sodium poly (meth) acrylate, sodium alginate, and water-soluble polyester, styrene-butadiene copolymer Polymer latex (SBR), nitrile rubber latex (NBR), vinyl acetate emulsion, ethylene / vinyl acetate copolymer emulsion, (meth) acrylic ester emulsion, vinyl chloride emma Water dispersible resins such John and the like, but are not necessarily limited to.
[0030]
In the present invention, PVA can be used in combination with fillers such as fine-particle synthetic silica, clay, talc, diatomaceous earth, zeolite, calcium carbonate, alumina, zinc oxide, satin white, and organic pigment. It is not limited.
[0031]
In the recording material of the present invention, a cationic resin can be used in combination as an ink fixing agent. The cationic resin is a monomer, oligomer or polymer of a primary to tertiary amine or quaternary ammonium salt that dissociates and exhibits cationic properties when dissolved in water, and preferably an oligomer or polymer. Specific examples include dimethylamine / epichlorohydrin polycondensate, acrylamide / diallylamine copolymer, polyvinylamine copolymer, dimethyldiallylammonium chloride polymer, polyethyleneimine, and the like. is not.
[0032]
As the supporting substrate used in the recording material of the present invention, any conventionally known supporting substrate that is transparent or opaque can be used. Examples of the transparent support substrate include polyester, polystyrene, polyamide, polyvinyl chloride, polymethyl methacrylate, cellulose acetate, polycarbonate, polyimide, cellophane, celluloid and other films, sheets, and highly transparent paper. Examples of the opaque support substrate include general paper, pigment-coated paper, cloth, wood, metal plate, synthetic paper, and a synthetic resin film or sheet subjected to opacification treatment.
[0033]
As a method for forming an ink absorbing layer containing PVA (A) and a maleic anhydride polymer (B) in or on the support substrate, an aqueous solution of PVA (A) and a maleic anhydride polymer (B) may be used. Or an aqueous solution or water dispersion comprising a mixture of PVA (A) and maleic anhydride polymer (B) with other water-soluble resin or water-dispersible resin and / or filler, size press, air knife coater , Impregnated into the supporting substrate by a usual coating method using a roll coater, bar coater, blade coater, curtain coater, cast coater, etc., or a coating layer on the upper surface of the supporting substrate or both the upper surface and the lower surface A method such as forming can be employed. Further, when the supporting substrate is paper, a method of internally adding the above aqueous solution or aqueous dispersion can be employed at the time of paper making. In the recording material of the present invention, having an ink absorbing layer in or on the surface of the supporting substrate means that the ink absorbing layer is provided in either the supporting substrate or the surface of the supporting substrate, or in the supporting substrate or on the surface of the substrate. It means both modes when both have an ink absorbing layer.
[0034]
In the present invention, the total content of PVA (A) and maleic anhydride polymer (B) in the recording material is not particularly limited, but is usually 0.1 to 200 g / m. ² Is preferably used in the range of 1 to 100 g / m. ² Often used within the range of
[0035]
【Example】
EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated further more concretely, this invention is not limited at all by these. Here, Examples 1 to 5, 10, 11, 13, 15, and 16 relate to recording materials obtained using modified PVA having no silyl group in the molecule, and are described for reference. To do. Examples of the present invention are Examples 6-9, 12, 14, and 17-19. In the following examples and comparative examples, “parts” and “%” mean “parts by weight” and “% by weight”, respectively, unless otherwise specified. In the following examples and comparative examples, PVA used for the production of an inkjet recording material was synthesized as follows.
[0036]
(1) Synthesis of PVA (PVA-3) containing ethylene units
Synthesis example 1
A 50 L pressure reactor equipped with a stirrer, nitrogen inlet, ethylene inlet, and initiator addition port was charged with 22.0 kg of vinyl acetate monomer and 8.0 kg of methanol, heated to 60 ° C., and then heated for 30 minutes. The system was replaced with nitrogen gas by bubbling. Next, ethylene was introduced and charged so that the pressure in the reaction vessel was 0.58 MPa. After adjusting the internal temperature of the reaction vessel to 60 ° C., 0.9 g of 2,2′-azobis (dimethylvaleronitrile) was added as an initiator to initiate polymerization. During the polymerization, ethylene was introduced to maintain the pressure in the reaction vessel at 0.58 MPa, the polymerization temperature at 60 ° C., and after 4 hours, when the polymerization rate reached 40%, the polymerization was terminated by cooling. After the reactor was opened and deethylene removal was performed, nitrogen gas was bubbled to completely remove ethylene. Subsequently, unreacted vinyl acetate monomer was removed while sometimes adding methanol under reduced pressure at 30 ° C. to obtain a methanol solution of an ethylene-vinyl acetate copolymer. Next, in a methanol solution of ethylene-vinyl acetate copolymer adjusted to a concentration of 35%, NaOH is added so that the alkali molar ratio (number of moles of NaOH / number of moles of vinyl acetate units in the polymer) is 0.08. Saponification was performed by adding a methanol solution (concentration 10%) to obtain ethylene-modified PVA (PVA-3). When the saponification degree of PVA-3 was measured according to JIS K6726, the saponification degree was 98.5 mol%. After the polymerization, the methanol solution of the ethylene-vinyl acetate copolymer obtained by removing the unreacted vinyl acetate monomer was precipitated in n-hexane and reprecipitation purification was dissolved three times, followed by 60 ° C. The ethylene-vinyl acetate copolymer purified by drying under reduced pressure was obtained. About this ethylene-vinyl acetate copolymer purified product, ¹ The ethylene modification amount determined from 1 H NMR measurement was 7 mol%. After saponifying the methanol solution of the ethylene-vinyl acetate copolymer with an alkali molar ratio of 0.2, methanol Soxhlet extraction was carried out for 3 days, followed by drying to obtain purified PVA. When the average degree of polymerization of the PVA was measured according to JIS K6726, it was 1000.
[0037]
Synthesis Example 2, Synthesis Example 3 and Synthesis Example 8
An ethylene-vinyl acetate copolymer was obtained in the same manner as in Synthesis Example 1 except that the conditions such as the vinyl acetate monomer, the amount of methanol, and the ethylene pressure during polymerization were changed as shown in Table 1. Next, ethylene-modified PVA (PVA-4, PVA-5, and PVA-) was prepared in the same manner as in Synthesis Example 1 except that the polymer concentration and alkali usage (alkali molar ratio) during saponification were changed as shown in Table 2. 11) was obtained.
[0038]
(2) Synthesis of PVA (PVA-6) having a silyl group
Synthesis example 4
A 50 L reactor equipped with a stirrer, reflux condenser, nitrogen inlet tube and thermometer was charged with 21.0 kg of vinyl acetate monomer, 90 g of vinyltrimethoxysilane and 9.0 kg of methanol, and bubbled with nitrogen gas for 30 minutes. Then degassed. The temperature of the reactor was increased, and when the internal temperature reached 60 ° C., 9.1 g of 2,2′-azobis (isobutyronitrile) was added to start polymerization, and after 4 hours, the polymerization rate was 50 %, The polymerization was stopped by cooling. Subsequently, unreacted vinyl acetate monomer was removed while sometimes adding methanol under reduced pressure at 30 ° C. to obtain a methanol solution of vinyl acetate copolymer. Next, saponification was performed by adding NaOH methanol solution (concentration 10%) having an alkali molar ratio of 0.03 to a methanol solution of vinyl acetate copolymer adjusted to a concentration of 25%, and PVA having a silyl group (PVA- 6) was obtained. As a result of measuring the saponification degree of PVA-6 according to JIS K6726, the saponification degree was 98.0 mol%. After the polymerization, the methanol solution of the vinyl acetate copolymer obtained by removing the unreacted vinyl acetate monomer was precipitated in n-hexane and reprecipitation purification was dissolved three times, followed by reducing the pressure at 60 ° C. A vinyl acetate copolymer purified by drying was obtained. About this vinyl acetate copolymer purified product, ¹ The amount of vinyltrimethoxysilane modification determined from 1 H NMR measurement was 0.25 mol%. After saponifying the methanol solution of the above vinyl acetate copolymer at an alkali molar ratio of 0.2, methanol Soxhlet extraction was carried out for 3 days, followed by drying to obtain a modified PVA purified product. The average degree of polymerization of the modified PVA was 1750 as measured according to JIS K6726.
[0039]
Synthesis Example 5, Synthesis Example 6, Synthesis Example 9 and Synthesis Example 10
A vinyl acetate copolymer was obtained in the same manner as in Synthesis Example 4 except that the amounts of vinyl acetate monomer, methanol, vinyltrimethoxysilane and initiator were changed as shown in Table 1. Next, PVA having a silyl group (PVA-7, PVA-8, PVA-8, PVA-8, PVA-8, PVA-8, and PVA-8), except that the polymer concentration and alkali usage (alkali molar ratio) during saponification were changed as shown in Table 2. PVA-12 and PVA-13) were obtained.
[0040]
(3) Synthesis of PVA (PVA-9) having an ethylene unit and a silyl group
Synthesis example 7
A 50 L pressurized reaction vessel equipped with a stirrer, nitrogen inlet, ethylene inlet and initiator addition port was charged with 24.8 kg of vinyl acetate monomer, 40 g of vinyltrimethoxysilane and 5.2 kg of methanol and heated to 60 ° C. After heating, the system was replaced with nitrogen gas by nitrogen bubbling for 30 minutes. Next, ethylene was introduced and charged so that the pressure in the reaction vessel was 0.46 MPa. After adjusting the internal temperature of the reaction vessel to 60 ° C., 0.8 g of 2,2′-azobis (dimethylvaleronitrile) was added as an initiator to initiate polymerization. During the polymerization, ethylene was introduced to maintain the pressure in the reaction vessel at 0.46 MPa and the polymerization temperature at 60 ° C., and after 4 hours, when the polymerization rate reached 40%, the polymerization was terminated by cooling. After the reactor was opened and deethylene removal was performed, nitrogen gas was bubbled to completely remove ethylene. Subsequently, unreacted vinyl acetate monomer was removed while sometimes adding methanol under reduced pressure at 30 ° C. to obtain a methanol solution of an ethylene-vinyl acetate copolymer. Next, saponification was performed by adding NaOH methanol solution (concentration 10%) having an alkali molar ratio of 0.05 to a methanol solution of ethylene-vinyl acetate copolymer adjusted to a concentration of 25%, so that ethylene units and silyl groups were obtained. PVA having (PVA-9) was obtained. When the saponification degree of PVA-9 was measured according to JIS K6726, the saponification degree was 98.5 mol%. After the polymerization, the methanol solution of the ethylene-vinyl acetate copolymer obtained by removing the unreacted vinyl acetate monomer was precipitated in n-hexane, and reprecipitation purification was performed three times, followed by 60 ° C. The ethylene-vinyl acetate copolymer purified by drying under reduced pressure was obtained. About this ethylene-vinyl acetate copolymer purified product, ¹ The ethylene modification amount determined from 1 H NMR measurement was 5 mol%, and the vinyltrimethoxysilane modification amount was 0.2 mol%. After saponifying the methanol solution of the ethylene-vinyl acetate copolymer with an alkali molar ratio of 0.2, methanol Soxhlet extraction was performed for 3 days, and then dried to obtain a modified PVA purified product. It was 1550 when the average degree of polymerization of this modified PVA was measured according to JIS K6726.
[0041]
[Table 1]

[0042]
[Table 2]

[0043]
Details of PVA used in the following examples and comparative examples are shown in Table 3.
[0044]
[Table 3]

[0045]
In the examples and comparative examples, various physical properties of the inkjet recording material were evaluated as follows.
(1) Inkjet recording method
Using a recording apparatus having a high on-mind type inkjet recording head having a discharge orifice diameter of 60 μm, color inkjet recording was performed using the following four colors of ink, and the recording characteristics were evaluated.
Yellow ink (composition)
CI Acid Yellow 2.3 2 parts
30 parts diethylene glycol
70 parts of water
Magenta ink (composition)
CI Acid Red 32 2 parts
30 parts diethylene glycol
70 parts of water
Cyan ink (composition)
CI Direct Blue 86 2 parts
30 parts diethylene glycol
70 parts of water
Black ink (composition)
CI Direct Black 19 2 parts
30 parts diethylene glycol
70 parts of water
[0046]
(2) Ink absorbability (ink absorption speed)
After ink jet recording, the print on the recording material was rubbed with a finger at regular intervals, and the time required until the printed part was not changed (until the printed part was not disturbed) was measured. The shorter the time, the higher the ink absorption rate.
(3) Bleeding degree
The diameter of the printed dots was measured with a stereomicroscope to determine how many times the ink droplets were formed. The lower the magnification, the less the bleeding and the better the sharpness of the image.
(4) Transparency
The visible light transmittance (%) of the non-printed portion of the recording material for inkjet was measured with a spectrophotometer using visible light having a wavelength of 500 nm. This transmittance is defined as transparency. It shows that transparency is so high that the transmittance | permeability is large.
(5) Water resistance
The inkjet recording material was immersed in distilled water at 20 ° C. for 1 minute, and then the sheet surface was rubbed with a finger and evaluated according to the following criteria.
○: The ink absorbing layer is hardly removed. Also, when the finger is separated from the sheet surface, finger stringing is not seen (good sticking resistance).
Δ: There is a slight drop of the ink absorbing layer. In addition, 2 to 3 strings are seen on the finger (slightly sticking resistance).
X: The ink absorbing layer is considerably dropped off. In addition, it is entangled on the entire surface of the finger and numerous stringing is observed (poor sticking resistance).
[0047]
Example 1 (Preparation of mat type ink absorbing layer)
A 10% aqueous solution (b) of PVA (A) (“PVA-110” manufactured by Kuraray Co., Ltd.) (PVA-1) having a polymerization degree of 1000 and a saponification degree of 98.5 mol% was prepared. While adding 400 parts of water to 100 parts of silica powder (“Mizukasil P-78D” manufactured by Mizusawa Chemical Co., Ltd.) and sufficiently dispersing it, 200 parts of aqueous solution (b) is slowly added at room temperature to prepare a silica dispersed aqueous solution of PVA did. 10.5 parts of a 10% aqueous solution of methyl vinyl ether / maleic anhydride alternating copolymer (“GANTREZ AN-119” manufactured by ISP) (B) is slowly added to a silica dispersion aqueous solution of PVA at room temperature with stirring, and an appropriate amount. 16% of distilled water was added to prepare a coating solution having a solid concentration of 16% {weight blend ratio: (B) / (A) = 5/95}. When this coating solution was allowed to stand at 30 ° C. for 2 weeks, the viscosity of the coating solution was hardly changed and the viscosity stability was good. Next, on the polyester film having a thickness of 50 μm and a transparency of 95%, the coating amount after drying (total solid content) is 15 g / m. ² {2.6 g / m in total solid content of PVA (A) and methyl vinyl ether / maleic anhydride alternating copolymer (B) ² } Was applied by hand coating to form an ink absorbing layer, and dried in a hot air dryer at 100 ° C. for 3 minutes to obtain an ink jet recording material. The results of evaluation on this sheet are shown in Table 4.
[0048]
Example 2
In Example 1, as PVA, PVA (A) having a polymerization degree of 1700 and a saponification degree of 98.5 mol% ("PVA-117" manufactured by Kuraray Co., Ltd.) (PVA-2) was used. Similarly, a coating solution was prepared to produce a recording material. Table 4 shows the results of evaluating the obtained recording material.
[0049]
Examples 3-12
In Example 1, the coating solution was used in the same manner as in Example 1 except that the type of PVA and / or the addition amount of 10% aqueous solution of methyl vinyl ether / maleic anhydride alternating copolymer was changed to the contents shown in Table 4. To prepare a recording material. Table 4 shows the results of evaluating the obtained recording material.
[0050]
Example 13 and Example 14
In Example 1, a commercially available ethylene / maleic anhydride alternating copolymer (Aldrich) was used in place of the methyl vinyl ether / maleic anhydride alternating copolymer, and the type of PVA was changed to that shown in Table 4. Except for the above, a coating solution was prepared in the same manner as in Example 1 to produce a recording material. Table 4 shows the results of evaluating the obtained recording material.
[0051]
Example 15 (Preparation of Gloss Type Ink Absorbing Layer)
A 10% aqueous solution of PVA (A) (“PVA-224” manufactured by Kuraray Co., Ltd.) (PVA-10) having a polymerization degree of 2400 and a saponification degree of 87.0 mol% was prepared. 30 parts of the above PVA aqueous solution was slowly added at room temperature to 100 parts of colloidal silica (“Snowtex 30” manufactured by Nissan Chemical Co., Ltd.) to prepare an aqueous colloidal silica dispersion of PVA. 1.6 parts of a 10% solution of methyl vinyl ether / maleic anhydride alternating copolymer (“GANTREZ AN-119” manufactured by ISP) (B) is slowly added to an aqueous colloidal silica dispersion of PVA with stirring at room temperature. An amount of distilled water was added to prepare a coating solution having a solid concentration of 20% {weight blending ratio: (B) / (A) = 5/95}. Next, on the polyester film having a thickness of 50 μm and a transparency of 95%, the coating amount after drying is 15 g / m. ² And then dried with a hot air dryer at 100 ° C. for 3 minutes to obtain an inkjet recording material. The results of evaluation on this sheet are shown in Table 4.
[0052]
Examples 16-18
In Example 15, the coating solution was used in the same manner as in Example 13 except that the type of PVA and / or the addition amount of 10% aqueous solution of methyl vinyl ether / maleic anhydride alternating copolymer was changed to the contents shown in Table 4. To prepare a recording material. Table 4 shows the results of evaluating the obtained recording material.
[0053]
Comparative Examples 1-4
In Example 1, the coating solution was used in the same manner as in Example 1 except that the type of PVA and / or the addition amount of 10% aqueous solution of methyl vinyl ether / maleic anhydride alternating copolymer was changed to the contents shown in Table 4. To prepare a recording material. Table 4 shows the results of evaluating the obtained recording material.
[0054]
Comparative Examples 5-7
In Example 13, a coating solution was prepared in the same manner as in Example 13 except that the type of PVA and the addition amount of 10% aqueous solution of ethylene / maleic anhydride alternating copolymer were changed to the contents shown in Table 4. A recording material was manufactured. Table 4 shows the results of evaluating the obtained recording material.
[0055]
Example 19
A recording material was produced in the same manner as in Example 1 except that a base material subjected to polyethylene laminate (15 μm) was used as the supporting substrate. Table 4 shows the results of evaluating the obtained recording material.
[0056]
[Table 4]

[0057]
【The invention's effect】
The recording material of the present invention is excellent in water resistance and sticking resistance, has a low degree of print bleeding, and is excellent in the sharpness of a recorded image, and is also excellent in ink absorbability.

Claims (3)

Weight of a surface of the supporting base, containing modified polyvinyl alcohol (A) and maleic anhydride-based polymer having a silyl group in the molecule (B), polyvinyl alcohol (A) and maleic anhydride-based polymer (B) A recording material having an ink absorbing layer having a blending ratio (B) / (A) of 0.1 / 99.9 to 40/60. The recording material according to claim 1, wherein the polyvinyl alcohol (A) is a polyvinyl alcohol containing 1 to 20 mol% of ethylene units. The recording material, the recording material according to claim 1 or 2 which is a recording material for inkjet Tsu and.