JP2004291237A - Ink jet recording medium and ink jet recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink jet recording medium which shows high image density and superb ink grab, and an ink jet recording method. <P>SOLUTION: The ink jet recording medium shows a surface zeta potential of +5 to +30 mv at pH7 of the recording surface of an ink jet recording medium having at least one ink absorbing layer formed on a support, and the ink jet recording method using the medium is provided. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０１８６】
一般式（１）において、Ｘ^１は、金属イオンと少なくとも２座の配位結合を形成可能な構造を有する原子の集まりを表し、Ｙ^１は芳香族炭化水素環、５〜６員の複素環又は−Ｌ^４＝Ｙ^２を表し、Ｙ^２は含窒素の５〜６員の複素環を表す。Ｌ^１、Ｌ^４は置換又は非置換のメチン基並びに窒素原子を表し、Ｌ^２、Ｌ^３は置換又は非置換のメチン基を表す。Ｍは金属イオンを表し、Ｘ^１で形成される原子の集まりと少なくとも２座の配位結合を形成している。ｍは０、１、２又は３の整数を表し、ｎ１は１、２又は３の整数を表す。
【０１８７】
又、一般式（２）において、Ｘ^３、Ｙ^３、Ｍ^３及びｎ２は、それぞれ上記Ｘ^１、Ｙ^１、Ｍ及びｎ１と同義である。
【０１８８】
一般式（１）、一般式（２）で表される色素の具体例は、前記特開平１０−２０５５９号の段落「００４３」〜「００５６」にＤ−１〜Ｄ−７０として記載がある。
【０１８９】
本発明で言う色材含有ポリマー（樹脂）微粒子は、ポリマー量として着色樹脂微粒子が分散されたインク中に０．５〜５０質量％配合されることが好ましく、０．５〜３０質量％配合されることが更に好ましい。上記ポリマーの配合量が０．５質量％に満たないと色材の保護能が十分でなく、５０質量％を超えると、サスペンションのインクとしての保存安定性が低下したり、ノズル先端部でのインク蒸発に伴うインクの増粘やサスペンションの凝集が起こることによってプリンタヘッドの目詰りが起こる場合がある。
【０１９０】
一方、上記色材は、該インク中に１〜３０質量％配合されることが好ましく、１．５〜２５質量％配合されることが更に好ましい。上記色材の配合量が１質量％に満たないと印字濃度が不十分であり、３０質量％を超えるとサスペンションの経時安定性が低下し、凝集等による粒径増大の傾向がある。
【０１９１】
本発明で言う色材を含有するポリマーから成る着色樹脂微粒子を含有する記録液（インク）は、水を媒体とすることが好ましく、上記色材を封入したポリマーのサスペンションから成り、該サスペンションには従来公知の各種添加剤、例えば多価アルコール類のような湿潤剤、分散剤、シリコーン系等の消泡剤、クロロメチルフェノール系等の防黴剤及び／又はＥＤＴＡ（エチレンジアミン四酢酸）等のキレート剤、又、亜硫酸塩等の酸素吸収剤等が含有されてもよい。
【０１９２】
上記湿潤剤としては、例えばエチレングリコール、プロピレングリコール、ジエチレングリコール、トリエチレングリコール、テトラエチレングリコール、ポリエチレングリコール、グリセリン、ジエチレングリコールジエチルエーテル、ジエチレングリコールモノブチルエーテル、エチレングリコールモノメチルエーテル、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ブチルエーテル、メチルカルビトール、エチルカルビトール、ブチルカルビトール、エチルカルビトールアセテート、ジエチルカルビトール、トリエチレングリコールモノメチルエーテル、トリエチレングリコールモノエチルエーテル、プロピレングリコールモノメチルエーテル等の多価アルコール及びそのエーテル、アセテート類、Ｎ−メチル−２−ピロリドン、１，３−ジメチルイミダゾリジノン、トリエタノールアミン、ホルムアミド、ジメチルホルムアミド等の含窒素化合物類、ジメチルサルフォキサイドの１種又は２種以上を使用することができる。
【０１９３】
これらの湿潤剤の配合量に特に制限はないが、上記インク中に好ましくは０．１〜５０質量％配合することができ、更に好ましくは０．１〜３０質量％配合することができる。
【０１９４】
前記分散剤としては特に制限されるものではないが、そのＨＬＢ値が８〜１８であることが、分散剤としての効果が発現し、サスペンションの粒子径の増大抑制効果がある点から好ましい。分散剤として市販品も使用することができる。そのような市販品としては、例えば花王社製の分散剤デモールＳＮＢ，ＭＳ，Ｎ，ＳＳＬ，ＳＴ，Ｐが挙げられる。
【０１９５】
分散剤の配合量に特に制限はないが、着色樹脂微粒子が分散されたインク中に０．０１〜１０質量％配合されることが好ましい。配合量が０．０１質量％に満たないとサスペンションの小粒径化が困難な場合があり、１０質量％を超えるとサスペンションの粒径が増大したりサスペンション安定性が低下し、ゲル化するおそれがある。
【０１９６】
又、前記消泡剤としては、特に制限なく市販品を使用することができる。そのような市販品としては、例えば信越シリコーン社製のＫＦ９６、６６、６９、ＫＳ６８、６０４、６０７Ａ、６０２、６０３、ＫＭ７３、７３Ａ、７３Ｅ、７２、７２Ａ、７２Ｃ、７２Ｆ、８２Ｆ、７０、７１、７５、８０、８３Ａ、８５、８９、９０、６８−１Ｆ、６８−２Ｆ等が挙げられる。
【０１９７】
これら化合物の配合量に特に制限はないが、着色樹脂微粒子が分散されたインク中に０．００１〜２質量％配合されることが好ましい。配合量が０．００１質量％に満たないとインク調製時に泡が発生し易く、又、インク内での小泡の除去が難しく、２質量％を超えると泡の発生は抑えられるものの、印字の際、インク内でハジキが発生し印字品質の低下が起こる場合がある。
【０１９８】
次に、着色樹脂微粒子が分散された記録液（インク）の製造方法について説明する。本発明のインクは各種の乳化法で製造することができ、乳化法として各種の方法を用いることができる。それらの例は、例えば「機能性乳化剤・乳化技術の進歩と応用展開，シー・エム・シー社刊」の８６頁の記載にまとめられている。本発明においては、特に超音波、高速回転剪断、高圧による乳化分散装置を使用することが好ましい。
【０１９９】
超音波による乳化分散では、所謂バッチ式と連続式の二通りが使用可能である。バッチ式は比較的少量のサンプル作製に適し、連続式は大量のサンプル作製に適する。連続式では、例えばＵＨ−６００ＳＲ（エスエムテー社製）のような装置を用いることが可能である。このような連続式の場合、超音波の照射時間は、分散室容積／流速×循環回数で求めることができる。超音波照射装置が複数ある場合は、それぞれの照射時間の合計として求められる。超音波の照射時間は、実際上は１０，０００秒以下である。１０，０００秒を超える時間が必要だと工程の負荷が大きく、実際上は乳化剤の再選択などにより乳化分散時間３７を短くする必要がある。そのため１０，０００秒を超える時間は必要でない。より好ましくは１０〜２，０００秒である。
【０２００】
高速回転剪断による乳化分散装置としては、「機能性乳化剤・乳化技術の進歩と応用展開」（前出）の２５５〜２５６頁に記載されるような、ディスパーミキサーや、２５１頁に記載されるようなホモミキサー、２５６頁に記載されるようなウルトラミキサー等が使用できる。これらの型式は乳化分散時の液粘度によって使い分けることができる。高速回転剪断による乳化分散機では、攪拌翼の回転数が重要である。ステーターを有する装置の場合、攪拌翼とステーターとのクリアランスは通常０．５ｍｍ程度で極端に狭くはできないので、剪断力は主として攪拌翼の周速に依存する。周速が５〜１５０ｍ／ｓｅｃであれば、本発明の乳化・分散に使用できる。周速が遅い場合、乳化時間を延ばしても小粒径化が達成できない場合が多く、１５０ｍ／ｓｅｃにするにはモーターの性能を極端に上げる必要があるからである。更に好ましくは２０〜１００ｍ／ｓｅｃである。
【０２０１】
高圧による乳化分散では、ＬＡＢ２０００（エスエムテー社製）等が使用できるが、その乳化・分散能力は、試料に掛けられる圧力に依存する。圧力は１０^４〜５×１０^５ｋＰａの範囲が好ましい。又、必要に応じて数回、乳化・分散を行い、目的の粒径を得ることができる。圧力が低すぎる場合、何度乳化分散を行っても目的の粒径は達成できない場合が多く、又、圧力を５×１０^５ｋＰａにするためには、装置に大きな負荷がかかり実用的ではない。より好ましくは５×１０^４〜２×１０^５ｋＰａの範囲である。
【０２０２】
これらの乳化・分散装置は単独で用いてもよいが、必要に応じて組み合わせて使用することが可能である。
【０２０３】
又、本発明のインクは、上記の装置を用いる他、いわゆる転相乳化によっても製造できる。転相乳化とは、前記ポリマーを前記染料と共にエステル、ケトンなどの有機溶剤に溶解させ、必要に応じて中和剤を加えて該ポリマー中のカルボキシル基をイオン化し、次いで水相を加えた後、前記有機溶剤を溜去して水系に転相することから成る。転相が完了した後、系を減圧下に加熱することにより、前記エステル、ケトン系溶剤を除去すると共に、所定量の水を除去して所望の濃度を有する着色樹脂微粒子が分散された水系インクが得られる。
【０２０４】
次に、本発明のインクジェット記録方法について説明する。前記本発明のインクジェット記録媒体に、前記記録液を使用してインクジェット記録する方法は、特に限定されるものではなく、ピエゾ方式やサーマル方式のインクジェットプリンターを使用することにより印字又は画像を得ることができる。記録方法の詳細は、例えば、インクジェット記録技術の動向（中村孝一編、平成７年３月３１日、日本科学情報株式会社発行）に記載されている。本発明の記録方法で用いることのできるインクジェットヘッドとしては、オンデマンド方式でもコンティニュアス方式でも構わない。又、インク吐出方式としては、電気−機械変換方式（シングルキャビティー型、ダブルキャビティー型、ベンダー型、ピストン型、シェアーモード型、シェアードウォール型等）、電気−熱変換方式（サーマルインクジェット型、バブルジェット（Ｒ）型等）、静電吸引方式（電界制御型、スリットジェット型等）及び放電方式（スパークジェット型等）などを具体例として挙げることができるが、何れの吐出方式を用いても構わない。
【０２０５】
【実施例】
以下に実施例を挙げて本発明を具体的に説明するが、本発明の実施態様はこれらに限定されるものではない。
【０２０６】
〈支持体の作製〉
含水率６．５％、坪量１７０ｇ／ｍ^２の写真用原紙の裏面に、溶融押し出し塗布法により密度０．９２の低密度ポリエチレンを３０μｍの厚さで塗布した。次いで、表側にアナターゼ型酸化チタン５．５％を含有する密度０．９２の低密度ポリエチレンを３５μｍの厚さで溶融押し出し法で塗布して、両面をポリエチレンで被覆した支持体を作製した。
【０２０７】
表側にコロナ放電を行い、ゼラチン下引き層を厚さ０．３ｇ／ｍ^２、裏面にもコロナ放電を行った後、ラテックス層を厚さ０．２ｇ／ｍ^２になるように塗布した。
【０２０８】
〈酸化チタン分散液１の調製〉
平均粒径が約０．２５μｍの酸化チタン２０ｋｇ（石原産業製：Ｗ−１０）を、ｐＨ＝７．５のトリポリリン酸ナトリウム１５０ｇ、ポリビニルアルコール（クラレ株式会社製：ＰＶＡ２３５）５００ｇ、カチオン性ポリマー（Ｐ−１）１５０ｇ及びサンノブコ株式会社の消泡剤ＳＮ３８１を１０ｇ含有する水溶液９０Ｌに添加し、高圧ホモジナイザー（三和工業株式会社製）で分散した後、全量を１００Ｌに仕上げて均一な酸化チタン分散液１を得た。
【０２０９】
【化２】

【０２１０】
〈蛍光増白剤分散液１の調製〉
チバガイギー株式会社製の油溶性蛍光増白剤ＵＶＩＴＥＸ−ＯＢの４００ｇを、ジイソデシルフタレートの９０００ｇ及び酢酸エチルの１２Ｌに加熱溶解し、これを酸処理ゼラチン３５００ｇ、カチオン性ポリマー（Ｐ−１）０．８ｋｇ、サポニン５０％水溶液６Ｌとを含有する水溶液６５Ｌに添加混合し、三和工業株式会社製の高圧ホモジナイザーで乳化分散し、減圧下で酢酸エチルを除去した後、全量を１００Ｌに仕上げて、蛍光増白剤分散液１を調製した。
【０２１１】
〈シリカ分散液１の調製〉
水系媒体（以後Ａ液と称す）として、
水 ８０Ｌ
ほう酸 ０．２７ｋｇ
ほう砂 ０．２３ｋｇ
５％硝酸 ０．４Ｌ
エタノール １．８Ｌ
カチオン性ポリマー （Ｐ−１）（２５質量％水溶液） ５Ｌ
を混合、溶解した。シリカとして沈降法シリカ（トクヤマ社製：商品名：Ｔ−３２、平均２次粒径１．５μｍ：以後Ｔ−３２と称す）３２ｋｇを用意し、以下のように分散し分散液１を得た。Ａ液を１．５６ｋｇ／ｍｉｎ、Ｔ−３２を０．４４ｋｇ／ｍｉｎの割合で分散機１としてフロージェットミキサー３００型（ピンミキサータイプ、粉研パウテックス製、以下ＦＪＭと称す）に供給した。その後、分散機２としてファインフローミルＦＭ−２５（連続式高速撹拌型分散機、大平洋機工製、以下ＦＭと称す）に供給した。その後、分散機３としてＬＭＫ−４（連続式湿式メディア型粉砕機、アシザワ製、以後ＬＭＫと称す）を用い、分散機２からでてきた分散液を、モノーポンプを用いＬＭＫに２．０ｋｇ／ｍｉｎで供給した。ＦＪＭの条件は周速２５ｍ／ｓｅｃ、滞留時間２０ｓｅｃ、ＦＭの条件は周速２５ｍ／ｓｅｃ、滞留時間０．１５ｓｅｃ、ＬＭＫの条件は、ビーズ径０．５ｍｍジルコニア、滞留時間５ｍｉｎ、ロータ回転周速１１ｍ／ｓｅｃ。その後、ＬＭＫからでてきた分散液を、フィルター処理を行った。フィルターは日本ポール社製のプロファイルを用いた。このときのシリカの平均粒径は２１０ｎｍであった。平均粒径はマルバーン社製ゼータサイザー１０００ＨＳで測定した値である。
【０２１２】
〈シリカ分散液２の調製〉
カチオン性ポリマー（Ｐ−１）（２５質量％水溶液）を２０Ｌとした以外は、シリカ分散液１と同様に作製した。平均粒径は２２０ｎｍであった。
【０２１３】
〈シリカ分散液３の調製〉
カチオン性ポリマー（Ｐ−１）（２５質量％水溶液）を３０Ｌとした以外は、シリカ分散液１と同様に作製した。平均粒径は２４０ｎｍであった。
【０２１４】
〈シリカ分散液４の調製〉
シリカをゲル法シリカ（日本シリカ社製、商品名：ＡＺ−２０４、平均２次粒径１．３μｍ）に変えた以外は、シリカ分散液１と同様に分散を行った。平均粒径は２２０ｎｍであった。
【０２１５】
〈シリカ分散液５の調製〉
シリカを気相法シリカ（日本アエロジル社製、商品名：Ａ−３００）に変え、ＬＭＫのロータ回転周速を８ｍ／ｓｅｃにした以外は、シリカ分散液１と同様に分散を行った。平均粒径は１９０ｎｍであった。
【０２１６】
〈シリカ分散液６の調製〉
シリカを気相法シリカ（日本アエロジル社製、商品名：Ａ−３００）に変え、カチオン性ポリマー（Ｐ−１）（２５質量％水溶液）を３０Ｌとし、ＬＭＫのロータ回転周速を８ｍ／ｓｅｃにした以外は、シリカ分散液１と同様に分散を行った。平均粒径は２００ｎｍであった。
【０２１７】
［インクジェット記録媒体１の作製］
〈塗布液の調製〉
第１層、第２層、第３層の塗布液を以下の手順で調製した。
【０２１８】
第１層用塗布液
シリカ分散液１を分散液のシリカ質量濃度が１０％になるように調整した調製分散液５６０ｍｌに４０℃で攪拌しながら、以下の添加剤を順次混合した。
【０２１９】
ポリビニルアルコール
（クラレ工業株式会社製：ＰＶＡ２０３）の１０％水溶液 ０．６ｍｌ
ポリビニルアルコール
（クラレ工業株式会社製：ＰＶＡ２３５）の５％水溶液 １５０ｍｌ
ポリビニルアルコール
（クラレ工業株式会社製：ＰＶＡ２４５）の５％水溶液 １００ｍｌ
蛍光増白剤分散液１ ３２ｍｌ
酸化チタン分散液１ ３０ｍｌ
ラテックスエマルジョン（第一工業株式会社製：ＡＥ−８０３） ２１ｍｌ
純水で全量を１０００ｍｌに仕上げる。
【０２２０】
第２層用塗布液
シリカ分散液１を分散液のシリカ質量濃度が１０％になるように調整した調製分散液６３０ｍｌに４０℃で攪拌しながら、以下の添加剤を順次混合した。
【０２２１】
ポリビニルアルコール
（クラレ工業株式会社製：ＰＶＡ２０３）の１０％水溶液 ０．６ｍｌ
ポリビニルアルコール
（クラレ工業株式会社製：ＰＶＡ２３５）の５％水溶液 １５０ｍｌ
ポリビニルアルコール
（クラレ工業株式会社製：ＰＶＡ２４５）の５％水溶液 １００ｍｌ
蛍光増白剤分散液１ ５０ｍｌ
純水で全量を１０００ｍｌに仕上げる。
【０２２２】
第３層用塗布液
シリカ分散液１を分散液のシリカ質量濃度が１０％になるように調整した調製分散液６４０ｍｌに４０℃で攪拌しながら、以下の添加剤を順次混合した。
【０２２３】
ポリビニルアルコール
（クラレ工業株式会社製：ＰＶＡ２０３）の１０％水溶液 ０．６ｍｌ
ポリビニルアルコール
（クラレ工業株式会社製：ＰＶＡ２３５）の５％水溶液 １５０ｍｌ
ポリビニルアルコール
（クラレ工業株式会社製：ＰＶＡ２４５）の５％水溶液 １００ｍｌ
シリコン分散液
（東レ・ダウコーニング・シリコーン株式会社製：ＢＹ−２２−８３９）
３．５ｍｌ
サポニン５０％水溶液 ４ｍｌ
フッ素系ノニオン性界面活性剤５％水溶液 ２ｍｌ
純水で全量を１０００ｍｌに仕上げる。
【０２２４】
〈塗布〉
上記のようにして得られた塗布液を、ポリエチレンで両面を被覆した前記の支持体の表側に、第１層（４０μｍ）、第２層（１１０μｍ）、第３層（３０μｍ）の順になるように各層を同時塗布した。かっこ内はそれぞれの湿潤膜厚を示す。塗布は、それぞれの塗布液を４０℃で３層式カーテンコーターで同時塗布を行い、塗布直後に８℃に保持した冷却ゾーンで２０秒間冷却した後、２０〜３０℃の風で６０秒間、４５℃の風で６０秒間、５０℃の風で６０秒間順次乾燥した（恒率乾燥域における皮膜温度は８〜２５℃であり、減率乾燥域で皮膜温度は徐々に上昇した）後、２３度、相対湿度４０〜６０％で調湿した。
【０２２５】
次に、酢酸エチルに溶解したイソシアネート系化合物（日本ポリウレタン工業株式会社製コロネート３０４１と、住友バイエルウレタン株式会社製スミジュールＮ３３００の２：８（質量比）の混合物）を２．０ｇ／ｍ^２になるようにオーバーコートし、インクジェット記録媒体１を得た。
【０２２６】
［インクジェット記録媒体２〜８の作製］
シリカ分散液２〜６に変更した以外は上記インクジェット記録媒体１と同様にして、インクジェット記録媒体２〜６を作製した。更に、シリカ分散液３、６に変更し、イソシアネート系化合物をオーバーコートしなかった以外は上記インクジェット記録媒体１と同様にして、インクジェット記録媒体７、８を作製した。
【０２２７】
表１に得られたインクジェット記録媒体についてシリカ分散液、表面ゼータ電位、７５度鏡面光沢度を示す。記録媒体の表面ゼータ電位は、大塚電子製レーザーゼーター電位計ＥＬＳ−８０００及び平板試料用セルを用いて測定した。具体的には、ｐＨ７．０、濃度１０ｍＭのＮａＣｌ水溶液を電解質として用い、ポリスチレンラテックスをモニター粒子として電気浸透流を測定し、これを解析することにより求めた。光沢度は日本電色工業社製ＶＧＳ−１００１ＤＰ型光沢度計を用いて入射角７５°、受光角７５°でＪＩＳ Ｚ ８７４１による光沢度を測定した値である。
【０２２８】
【表１】

【０２２９】
［記録液１の調製（染料系）］
下記に示す各成分を混合し、十分攪拌して溶解後、０．８μｍのメンブレンフィルターによって濾過してゴミ及び粗大粒子を除去し、インクジェット用の記録液１を調製した。ゼータ電位は＋４８ｍＶであった。記録液のゼータ電位は大塚電子製レーザーゼーター電位計ＥＬＳ−８０００を用いて算出した。
【０２３０】
Ｃ．Ｉ．ダイレクトブルー１９９ ３質量％
エチレングリコール ７質量％
ジエチレングリコール １０質量％
コロイダルシリカ（スノーテックスＡＫ、日産化学工業社製） ３質量％
サーフィノール４６５（日信化学工業社製） ０．１質量％
水 ７６．９質量％
［記録液２の調製（染料系）］
上記記録液１のコロイダルシリカ（スノーテックスＡＫ、日産化学工業社製）をコロイダルシリカ（スノーテックス２０、日産化学工業社製）に変えた以外は同様にして、インクジェット用の記録液２を調製した。ゼータ電位は−５１ｍＶであった。
【０２３１】
［記録液３の調製（顔料系）］
下記に示す各成分によって顔料分散液を調製し、これを用いて記録液を調製した。
【０２３２】
〈顔料分散液の調製〉
Ｃ．Ｉ．ピグメントブルー１５ １０質量％
スチレン−アクリル酸−アクリル酸エチル共重合体
（質量平均分子量５０００） １．５質量％
モノエタノールアミン １質量％
ジエチレングリコール ５質量％
水 ８２．５質量％
上記成分を混合し、３０分間プレミキシングを行った後、サンドミルで分散処理を行った。更に、遠心分離処理を行い、粗大粒子を除去して分散液とした。
【０２３３】
上記の顔料分散液を使用し、下記に示す各成分を混合し、十分攪拌後、０．８μｍのメンブレンフィルターによって濾過してゴミ及び粗大粒子を除去し、インクジェット用の記録液３を調製した。ゼータ電位は−３２ｍＶであった。
【０２３４】
上記顔料分散液 ３０質量％
グリセリン １０質量％
エチレングリコール ５質量％
エチルアルコール ２質量％
水 ５３質量％
［記録液４の調製（顔料系）］
上記記録液３の水の５質量％をコロイダルシリカ（スノーテックスＡＫ、日産化学工業社製）に変えた以外は同様にして、インクジェット用の記録液４を調製した。ゼータ電位は＋２５ｍＶであった。
【０２３５】
［記録液５〜７の調製（着色樹脂微粒子系）］
〈着色樹脂微粒子分散液５の調製〉
ポリマーとして、ポリビニルブチラール（積水化学（株）製ＢＬ−Ｓ、平均重合度３５０）１５ｇ、ジョンクリル６７（ジョンソンポリマー（株）製）５ｇ、色材として、シアン染料（Ｃ．Ｉ．ソルベントブルー７０）１０ｇ、及び酢酸エチル１５０ｇをセパラブルフラスコに入れ、フラスコ内をＮ_２で置換した後、攪拌して上記各ポリマー及び染料を完全溶解させた。次いで、ジョンクリル６７を中和するのに必要な水酸化ナトリウム及びラウリル硫酸ナトリウム３ｇを含む水溶液１５０ｇを滴下、撹拌した後、超音波分散機（ＵＨ−１５０型、株式会社エスエムテー製）を用いて７０℃、３００秒間乳化した。その後、減圧下で酢酸エチルを除去して染料を含浸する着色樹脂微粒子分散液５を得た。この着色樹脂微粒子分散液５におけるシェルポリマーはジョンクリル６７で、総ポリマーに対する比率は２５質量％である。
【０２３６】
〈着色樹脂微粒子分散液６の調製〉
ポリマーとして、ポリビニルブチラール（積水化学（株）製ＢＬ−Ｓ、平均重合度３５０）１５ｇ、色材として、シアン染料（Ｃ．Ｉ．ソルベントブルー７０）１０ｇ、及び酢酸エチル１５０ｇをセパラブルフラスコに入れ、フラスコ内をＮ_２で置換した後、攪拌して上記ポリマー及び染料を完全溶解させた。次いで、ポリビニルアルコール樹脂（ＭＰ−２０３、クラレ（株）製）３ｇ及びラウリル硫酸ナトリウム３ｇを含む水溶液１５０ｇを滴下、撹拌した後、超音波分散機（ＵＨ−１５０型、株式会社エスエムテー製）を用いて７０℃、３００秒間乳化した。その後、減圧下で酢酸エチルを除去し、染料を含浸する着色樹脂微粒子分散液６を得た。この着色樹脂微粒子分散液６におけるシェルポリマーはＭＰ−２０３で、総ポリマーに対する比率は１６．７質量％である。
【０２３７】
〈着色樹脂微粒子分散液７の調製〉
上記着色樹脂微粒子分散液５の調製において、ジョンクリル６７及び水酸化ナトリウムを添加しなかった以外は同様にして、着色樹脂微粒子分散液７を調製した。
【０２３８】
上記の着色樹脂微粒子分散液５〜７を使用し、下記に示す各成分を混合し、十分攪拌後、０．８μｍのメンブレンフィルターによって濾過してゴミ及び粗大粒子を除去し、インクジェット用の記録液５〜７を調製した。
【０２３９】
着色樹脂微粒子分散液５〜７ ６９．９質量％
エチレングリコール １５質量％
グリセリン １５質量％
サーフィノール４６５（日信化学工業社製） ０．１質量％
〈記録液の各特性値の測定〉
上記調製した着色樹脂微粒子を含有する記録液について、下記の方法に従って、体積平均粒径、その変動係数、コアシェル化の確認及びコアとシェルの色材濃度比、ゼータ電位について算出し、得られた結果を表２に示す。
【０２４０】
体積平均粒径は、大塚電子製レーザー粒径解析システムを用いて測定した。
ＴＥＭ写真の投影面積の平均値から得られた円換算平均粒径を、球形換算して体積平均粒径とその標準偏差を求め体積平均粒径で割ることで変動係数を求めた。
【０２４１】
コアシェル化の確認は、サスペンションの超薄切片をカーボン支持膜付きメッシュに固定後、ＲｕＯ_４で染色し、各々比較例と比べ、染色度合から確認した。
【０２４２】
コア／シェルにおける色材の色材含有率（濃度）比の算出は、以下のようにして行った。
【０２４３】
Ｓｉ−ウェーファー上に調製した着色樹脂微粒子を塗布乾燥し、Ｐｈｙｓｉｃａｌ Ｅｌｅｃｔｒｉｎｉｃｓ社製のＴＲＩＦＴ−ＩＩを用いて、以下の条件で色材としての色素の質量数＋１のエリア強度を、０．５〜１０００ａ．ｍ．ｕ．の全検出イオン強度で割り、この値をコアのみの粒子とコア／シェル粒子とをそれぞれ比較することで、コアとシェルの色材含有率（濃度）比を算出した。
【０２４４】
装置名；ＴＲＩＦＴ−ＩＩ
メーカー；Ｐｈｙｓｉｃａｌ Ｅｌｅｃｔｒｉｎｉｃｓ社
一次イオン；Ｇａ^＋
加速電圧；１５ｋＶ
測定質量範囲；０．５〜１０００ａ．ｍ．ｕ．
測定エリア；６０μｍ×６０μｍ
検出イオン；正二次イオン検出
積算時間；５分間
測定温度；液体窒素で冷却
ステージ電圧；３０００Ｖ
ゼータ電位は大塚電子製レーザーゼーター電位計ＥＬＳ−８０００を用いて算出した。
【０２４５】
【表２】

【０２４６】
［インクジェット画像の記録］
上記調製した記録液１〜７を、インクジェットカートリッジに収納した後、カラーインクジェットプリンターＰＭ８００Ｃ（セイコーエプソン社製）により、前記作製した記録媒体１〜８に、表３に記載の組み合わせで画像記録した。出力画像としては、出力濃度を０％から１００％の間を１６段階に分割したウェッジ画像（各濃度について３ｃｍ×３ｃｍのパッチ状に出力）を記録した。
【０２４７】
［記録画像の評価］
以上のようにして記録した各画像について、出力濃度１００％部の最大反射濃度の評価を行った。又、下記の方法に従って定着性（耐擦過性）の評価を行った。結果を表３に示す。
【０２４８】
〈定着性：耐擦過性の評価〉
上記出力した各画像の出力濃度１００％のパッチ部について、画像が表面になるように平面性が保たれた定盤に張り付け、消毒用ガーゼを付けた板（３ｃｍ角）に１９．６Ｎの荷重を掛けた器具を画像表面に押し当て、１００往復画像表面を擦った。擦る前と擦った後での画像の光学反射濃度を３点で測定し平均値を求めた。擦る前の光学反射濃度をＡ、擦った後での光学反射濃度をＢとした時、下記に従って画像残存率（％）を求め、これを耐擦過性の尺度とした。
【０２４９】
画像残存率（％）＝Ｂ／Ａ×１００
【０２５０】
【表３】

【０２５１】
表３より明らかなように、本発明のインクジェット記録媒体及びゼータ電位が負又は正の記録液で記録するインクジェット記録方法は、画像濃度、インク定着性に優れていることが分かる。
【０２５２】
【発明の効果】
本発明により、画像濃度、インク定着性に優れたインクジェット記録媒体及びインクジェット記録方法を提供することができた。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an ink jet recording medium and an ink jet recording method, and more particularly, to an ink jet recording medium excellent in image density and fixability of an ink jet recorded image, and an ink jet recording method.
[0002]
[Prior art]
Ink-jet recording is the recording of images and characters by flying fine droplets of ink by various operating principles and attaching them to a recording sheet such as paper. Has an advantage that it is easy.
[0003]
With regard to clogging and maintenance of nozzles, which has been a problem in the conventional recording method, improvements have been made in both ink and equipment, and now they are rapidly spreading to various fields such as various printers, facsimile machines and computer terminals. are doing.
[0004]
The recording medium used in this ink jet recording method has a high density of print dots, a bright and vivid color tone, and the ink does not flow out or bleed even when the print dots overlap with each other due to rapid ink absorption. In addition, it is required that the diffusion of print dots in the horizontal direction is not unnecessarily large, and that the periphery is smooth and not blurred.
[0005]
In order to solve these demands, a great many techniques have been conventionally proposed. Recording paper in which a low-size base paper is wetted with a paint for surface processing (for example, see Patent Document 1); recording paper in which an ink-absorbing coating layer is provided on the surface of a support (for example, see Patent Document 2); Recording paper containing non-colloidal silica powder as the pigment in the coating layer (for example, see Patent Document 3), recording paper using both inorganic pigment and organic pigment (for example, see Patent Document 4), and two pore distributions Recording paper having a peak (for example, see Patent Literature 5), recording paper having two upper and lower porous layers (for example, see Patent Literature 6), and recording paper having irregular cracks (for example, Patent Literatures 7 to 7) 9), recording paper having a fine powder layer (for example, see Patent Documents 10 to 12), and recording paper containing a pigment having specific physical property values and fine particle silica (for example, see Patent Documents 13 to 17). , Colloidal silicon Recording paper containing fine-particle silica (for example, see Patent Documents 18 to 27), recording paper containing alumina hydrate fine particles (for example, see Patent Documents 28 to 34), and fine particles having a positive charge on the surface There are many known recording papers having an ink image receiving layer containing (for example, see Patent Documents 35 and 36).
[0006]
On the other hand, as a recording liquid (ink) applied to the ink jet recording method, a recording medium and an image recording method are used, which are suitable for the above-described recording medium, such as an aqueous ink, a pigment ink, a low-melting solid wax ink containing a dye, and an oil-soluble dye ink. Various things are known. An aqueous ink containing a water-soluble dye has an advantage that nozzle clogging is unlikely to occur, but there is a problem that a formed image is easily blurred and water resistance is poor. Ink containing a pigment is less likely to bleed and has good water resistance, but has a problem that image density and image quality are inferior, nozzle clogging is likely to occur, and sufficient fixability cannot be obtained. A wax ink containing a low-melting solid wax containing a dye is complicated by attaching it to a recording member and then fusing it to complete an image. Inks containing oil-soluble dyes include oil-based inks that use an oil-based medium such as an organic solvent and water-based inks that use an aqueous medium. The development of a water-based ink which is excellent in water resistance with less bleeding is desired. In particular, an aqueous ink in which an oil-soluble dye is impregnated in fine particles of a polymer (resin) is expected to be less likely to bleed and have excellent water resistance and to be less likely to cause nozzle clogging. As such an aqueous ink, an oil-soluble dye dissolved in an organic solvent is added to a latex obtained by emulsion polymerization of a vinyl monomer, and after stirring, the organic solvent is evaporated to use an aqueous ink using polymer fine particles impregnated with the oil-soluble dye. (For example, see Patent Document 37). Further, an aqueous ink using polymer fine particles obtained by adding an oil-soluble dye to a latex (polymer fine particles) obtained by emulsion-polymerizing a vinyl monomer with a low molecular surfactant and heating and stirring (for example, see Patent Documents 38 to 40) is disclosed. Have been. However, inks in which these oil-soluble dyes are impregnated in polymer fine particles have low image density, and are not easily bleeding and excellent in water resistance as well as hardly cause nozzle clogging, and the colored polymer (resin) fine particles have sufficient fixability. There is a problem that it cannot be obtained.
[0007]
As described above, these ink jet recording medium technologies and recording liquid (ink) composition technologies have not been able to satisfy the demands of the ink jet recording technology which has been highly developed in recent years, particularly, the image density and the fixing property of the coloring material. That is the fact.
[0008]
[Patent Document 1]
JP-A-52-53012
[0009]
[Patent Document 2]
JP-A-55-5830
[0010]
[Patent Document 3]
JP-A-56-157
[0011]
[Patent Document 4]
JP-A-57-107878
[0012]
[Patent Document 5]
JP-A-58-110287
[0013]
[Patent Document 6]
JP-A-62-111782
[0014]
[Patent Document 7]
JP-A-59-68292
[0015]
[Patent Document 8]
JP-A-59-123696
[0016]
[Patent Document 9]
JP-A-60-18383
[0017]
[Patent Document 10]
JP-A-61-135786
[0018]
[Patent Document 11]
JP-A-61-148092
[0019]
[Patent Document 12]
JP-A-62-149475
[0020]
[Patent Document 13]
JP-A-63-252779
[0021]
[Patent Document 14]
JP-A-1-108083
[0022]
[Patent Document 15]
JP-A-2-136279
[0023]
[Patent Document 16]
JP-A-3-65376
[0024]
[Patent Document 17]
JP-A-3-27976
[0025]
[Patent Document 18]
JP-A-57-14091
[0026]
[Patent Document 19]
JP-A-60-219083
[0027]
[Patent Document 20]
JP-A-60-210984
[0028]
[Patent Document 21]
JP-A-61-20797
[0029]
[Patent Document 22]
JP-A-61-188183
[0030]
[Patent Document 23]
JP-A-5-278324
[0031]
[Patent Document 24]
JP-A-6-92011
[0032]
[Patent Document 25]
JP-A-6-183134
[0033]
[Patent Document 26]
JP-A-7-137431
[0034]
[Patent Document 27]
JP-A-7-276789 (Claims)
[0035]
[Patent Document 28]
JP-A-2-276671
[0036]
[Patent Document 29]
JP-A-3-67684
[0037]
[Patent Document 30]
JP-A-3-215082
[0038]
[Patent Document 31]
JP-A-3-251488
[0039]
[Patent Document 32]
JP-A-4-67986
[0040]
[Patent Document 33]
JP-A-4-263983
[0041]
[Patent Document 34]
JP-A-5-16517
[0042]
[Patent Document 35]
Japanese Patent Application Laid-Open No. H11-147362 (Claims)
[0043]
[Patent Document 36]
Japanese Patent Application Laid-Open No. 2000-85241 (Claims)
[0044]
[Patent Document 37]
JP-A-54-58504
[0045]
[Patent Document 38]
JP-A-55-139471
[0046]
[Patent Document 39]
JP-A-62-172076
[0047]
[Patent Document 40]
JP-A-62-184072 (Claims)
[0048]
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an ink jet recording medium and an ink jet recording method which are excellent in image density and ink fixability after recording.
[0049]
[Means for Solving the Problems]
The above object of the present invention has been achieved by the following configurations.
[0050]
1. An ink jet recording medium characterized in that the surface zeta potential at pH 7 of the recording surface of the ink jet recording medium having at least one ink absorbing layer on a support is from +5 mV to +30 mV.
[0051]
2. 2. The ink jet recording medium according to the item 1, wherein the surface zeta potential is +10 mV or more and +25 mV or less.
[0052]
3. 3. An ink jet recording method, comprising: performing recording on the ink jet recording medium according to 1 or 2 using a recording liquid having a negative zeta potential.
[0053]
4. 4. The ink jet recording method according to the item 3, wherein the recording liquid contains a pigment as a coloring material.
[0054]
5. 4. The ink jet recording method according to the above item 3, wherein the recording liquid contains colored resin fine particles made of a polymer containing a coloring material.
[0055]
6. 6. The ink jet recording method according to the item 5, wherein the colored resin fine particles are colored resin fine particles comprising a polymer core and a polymer shell containing a coloring material.
[0056]
7. 7. The ink jet recording method according to any one of the items 3 to 6, wherein the zeta potential of the recording liquid is from -90 mV to -10 mV.
[0057]
8. 3. An ink jet recording method, comprising: performing recording on the ink jet recording medium according to 1 or 2 using a recording liquid having a positive zeta potential.
[0058]
9. 9. The ink jet recording method according to the above item 8, wherein the recording liquid contains a pigment as a coloring material.
[0059]
10. 9. The ink jet recording method according to the above item 8, wherein the recording liquid contains colored resin fine particles made of a polymer containing a coloring material.
[0060]
11. 11. The ink jet recording method according to the item 10, wherein the colored resin fine particles are colored resin fine particles comprising a polymer core and a polymer shell containing a coloring material.
[0061]
12. 12. The ink jet recording method according to any one of the items 8 to 11, wherein the zeta potential of the recording liquid is not less than +10 mV and not more than +90 mV.
[0062]
The present invention will be described in more detail.
The ink jet recording medium of the present invention (hereinafter also referred to as the recording medium of the present invention) has an ink absorbing layer on a support.
[0063]
The support used for the recording medium of the present invention may be any of a water-absorbing support and a non-water-absorbing support, but without wrinkles after printing, high quality without a difference in smoothness. A non-water-absorbing support is preferable because a print can be obtained and a glossy surface can be easily formed.
[0064]
As the water-absorbing support, a paper support mainly composed of natural pulp is typically used, but a mixture of synthetic pulp and natural pulp may be used. Examples of the non-water-absorbing support include a plastic resin film support and a support in which both surfaces of paper are covered with a plastic resin film. Examples of the plastic resin film support include a polyester film, a polyvinyl chloride film, a polypropylene film, a cellulose triacetate film, a polystyrene film, and a laminated film support thereof. These plastic resin films may be transparent or translucent. A particularly preferred support in the present invention is a support in which both sides of the paper are coated with a plastic resin, and the most preferred is a support in which both sides of the paper are coated with a polyolefin resin. Hereinafter, a particularly preferred support in which both surfaces of paper are coated with a polyolefin resin will be described.
[0065]
The paper used for the support is made of wood pulp as a main raw material, and if necessary, in addition to wood pulp, using synthetic pulp such as polypropylene or synthetic fiber such as nylon or polyester. As wood pulp, any of LBKP, LBSP, NBKP, NBSP, LDP, NDP, LUKP, NUKP (L is hardwood, N is conifer, BK is sulfate-exposed, BS is sulfite-exposed, and P is pulp) Although it can be used, it is preferable to use LBKP, NBSP, LBSP, NDP, and LDP, which contain a large amount of short fibers. However, the ratio of LBSP and / or LDP is preferably 10 to 70%.
[0066]
As the pulp, chemical pulp (sulfate pulp or sulfite pulp) having a small amount of impurities is preferably used, and pulp having improved whiteness by performing a bleaching treatment is also useful. In paper, sizing agents such as higher fatty acids and alkyl ketene dimers, white pigments such as calcium carbonate, talc and titanium oxide, paper strength agents such as starch, polyacrylamide and polyvinyl alcohol, fluorescent whitening agents, polyethylene glycols , Etc., a water retaining agent, a dispersant, a softening agent such as quaternary ammonium, etc. can be added as appropriate.
[0067]
The freeness of the pulp used for papermaking is preferably 200 to 500 ml according to the CSF specification, and the sum of the 24 mesh residue and the 42 mesh residue whose fiber length after beating is specified in JIS P 8207 is 30 to 500 ml. 70% is preferred. In addition, the 4 mesh residue is preferably 20% or less. The basis weight of the paper is preferably from 50 to 250 g, and particularly preferably from 70 to 200 g. The thickness of the paper is preferably 50 to 210 μm. The paper may be calendered at the papermaking stage or after the papermaking to provide high smoothness. Paper density is 0.7-1.2g / m²(JIS P 8118) is common. Further, the rigidity of the base paper is preferably from 20 to 200 g under the conditions specified in JIS P 8143.
[0068]
A surface sizing agent may be applied to the paper surface. As the surface sizing agent, the same sizing agents as can be added to the base paper can be used. The pH of the paper is preferably 5 to 9 when measured by a hot water extraction method specified in JIS P 8113.
[0069]
Next, the polyolefin resin covering both sides of the paper will be described. Examples of the polyolefin resin used for this purpose include polyethylene (PE), polypropylene (PP), and polyisobutylene. Polyolefins such as a copolymer mainly composed of propylene are preferable, and polyethylene is particularly preferable.
[0070]
Hereinafter, particularly preferred polyethylene will be described. The polyethylene covering the front and back surfaces of the paper is mainly low-density polyethylene (LDPE) and / or high-density polyethylene (HDPE), but other LLDPE (linear low-density polyethylene) and PP are also partially used. be able to. In particular, the polyolefin layer on the coating layer side preferably has improved opacity and whiteness by adding rutile or anatase type titanium oxide therein. The titanium oxide content is generally 1 to 20%, preferably 2 to 15%, based on the polyolefin. In the polyolefin layer, a pigment having high heat resistance and a fluorescent whitening agent for adjusting a white background can be added.
[0071]
Examples of the coloring pigment include ultramarine, navy blue, cobalt blue, phthalocyanine blue, manganese blue, cerulean blue, tungsten blue, molybdenum blue, anthraquinone blue, and the like. Examples of the fluorescent whitening agent include dialkylaminocoumarin, bisdimethylaminostilbene, bismethylaminostilbene, 4-alkoxy-1,8-naphthalenedicarboxylic acid-N-alkylimide, bisbenzoxazolylethylene, and dialkylstilbene. Can be
[0072]
The amount of polyethylene (PE) used on the front and back of the paper is selected so as to optimize the thickness of the ink absorbing layer and the curl in low and high humidity after the back layer is provided. Has a thickness of 15 to 40 μm on the ink absorbing layer side and 10 to 30 μm on the back layer side. The ratio of the front and back PEs is preferably set so as to adjust the curl that changes depending on the type and thickness of the ink absorbing layer, the thickness of the middle paper, and the like. / 1 to 1/3. Further, it is preferable that the PE-coated paper support has the following characteristics (1) to (7).
[0073]
(1) The tensile strength is preferably 2 to 30 kg in the vertical direction and 1 to 20 kg in the horizontal direction at a strength specified by JIS P 8113.
[0074]
(2) The tear strength is preferably 10 to 300 g in the vertical direction and 20 to 400 g in the horizontal direction, as defined by JIS P 8116.
[0075]
(3) The compression modulus is 9.8 × 10⁷Pa or more is preferable.
(4) The opacity is preferably 50% or more, particularly preferably 85 to 98%, as measured by the method specified in JIS P8138.
[0076]
(5) Whiteness is defined by L specified in JIS Z 8729.^*, A^*, B^*Is L^*= 80-95, a^*= -3 to +5, b^*= −6 to +2.
[0077]
(6) The Clark rigidity is such that the Clark rigidity in the transport direction of the recording medium is 20 to 400 cm.³/ 100 is preferred.
[0078]
(7) The moisture in the base paper is preferably 4 to 10% based on the middle paper.
The ink jet recording medium of the present invention preferably has an ink absorbing layer on the support.
[0079]
Next, the ink absorbing layer will be described. The recording medium of the present invention has at least one ink absorbing layer, and has a surface zeta potential at a pH of 7 on the recording surface of the recording medium of +5 mV or more and +30 mV or less. More preferably, it is +10 mV or more and +25 mV or less. As a result of extensive studies by the present inventors, by controlling the surface zeta potential within such a range and recording with a negative or positive zeta potential inkjet recording liquid (ink), excellent color density and fixability are exhibited. Was found. Although the reason is not clear, when an ink jet recording liquid (ink) having a negative charge or a positive charge is ejected onto the recording surface of the recording medium, the image density and the image density and the liquid density are increased due to an appropriate interaction between the recording liquid and the recording medium surface. It is considered that the ink fixability was improved. The surface zeta potential of the recording medium can be determined as follows using a commercially available device. The method of measurement is not particularly limited. For example, when a solution (pH 7) in which polymer particles are dispersed is brought into contact with the surface of a flat sample to be measured, and the polymer particles are electrophoresed, a change in the moving speed of the polymer particles causes a flat plate. The zeta potential on the sample surface can be determined. The production of a recording medium in which such a surface zeta potential is controlled can be achieved by overcoating the surface with various kinds of additives in the ink absorbing layer described below, the amount of the additive used, and after the ink absorbing layer is produced. .
[0080]
The ink absorbing layer may have two or more ink absorbing layers having different physical properties or constituent materials. For example, it is also possible to use an ink absorbing layer having a multilayer structure in which an ink absorbing layer having a controlled surface zeta potential is provided as an upper layer and an ink absorbing layer having a high ink absorbing function is provided as a lower layer. The ink absorbing layer may be provided on only one side of the support, or may be provided on both sides. At this time, the ink absorbing layers provided on both surfaces may be the same or different. The ink absorbing layer may be roughly divided into a swelling layer type ink absorbing layer and a void type ink absorbing layer. Further, a swelling type ink absorbing layer and a void type ink absorbing layer may be combined. For example, a layer configuration in which a swellable ink absorbing layer is provided on the side close to the support and a void type ink absorbing layer is provided on the side remote from the support, or a reverse layer configuration can be used. Further, in the case of a recording medium in which an ink absorbing layer is provided on both surfaces of the support, the same type of absorbing layer may be used on the front and back sides, or different types of ink absorbing layers may be used.
[0081]
Particularly preferred in the present invention is a void type ink absorbing layer. This is because a high quality print can be obtained because the ink absorption speed is high and the occurrence of unevenness is small.
[0082]
The swelling-type ink absorbing layer is mainly composed of a hydrophilic polymer having a swelling property with respect to an ink solvent. Examples of such a hydrophilic polymer include gelatin (alkali-treated gelatin, acid-treated gelatin, derivative gelatin in which an amino group is blocked with phenyl isocyanate or phthalic anhydride, etc.), polyvinyl alcohol (average degree of polymerization is 300 to 4000, saponification degree). Is preferably 80 to 99.5%), polyvinylpyrrolidone, polyethylene oxide, hydroxylethylcellulose, agar, pullulan, dextran, acrylic acid, carboxymethylcellulose, casein, alginic acid and the like, and two or more of them can be used in combination. Fine particles such as inorganic fine particles and organic fine particles may be contained in the swellable ink absorbing layer within a range that does not affect the swellability of the hydrophilic polymer, but the content is approximately 100% or less based on the hydrophilic binder. The amount of the hydrophilic polymer provided in the swelling layer is 1 m of the recording medium.²The weight is approximately 3 to 20 g, preferably 5 to 15 g.
[0083]
The porous ink absorbing layer is preferably a porous film having a porous layer formed of inorganic or organic fine particles and a small amount of a hydrophilic polymer. The fine particles are preferably inorganic fine particles. Examples of such inorganic fine particles include light calcium carbonate, heavy calcium carbonate, magnesium carbonate, kaolin, clay, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc hydroxide, zinc sulfide, zinc carbonate, White inorganic pigments such as hydrotalcite, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, synthetic amorphous silica, colloidal silica, alumina, colloidal alumina, pseudoboehmite, aluminum hydroxide, lithopone, zeolite, magnesium hydroxide, etc. Can be mentioned. The inorganic fine particles can be used as they are as primary particles, or can be used in a state where secondary aggregated particles are formed.
[0084]
Since particularly fine voids can be formed, silica synthesized by a usual wet method, colloidal silica, fine particle silica synthesized by a gas phase method or pseudo-boehmite is preferable, and especially synthetic silica having an average particle diameter of 300 nm or less, colloidal silica And pseudo-boehmite are preferred. The average particle diameter of the inorganic fine particles is determined, for example, by observing the cross section or surface of the particle itself or the void layer with an electron microscope, determining the particle diameter of 100 arbitrary particles, and calculating the simple average value (number average). . Here, each particle size is represented by a diameter assuming a circle equal to the projected area. The average particle size can also be determined from the coating liquid for forming the void layer by using the dynamic light scattering method. For example, it can be determined using a laser particle size analysis system manufactured by Otsuka Electronics Co., Ltd. or a Zetasizer manufactured by Malvern.
[0085]
As the hydrophilic polymer used for the void layer, the same as the hydrophilic polymer used for the swellable ink absorbing layer is used, and a preferred hydrophilic polymer is polyvinyl alcohol (PVA). The PVA used in the present invention includes, in addition to ordinary PVA obtained by hydrolyzing polyvinyl acetate, modified polyvinyl alcohol such as PVA having a cation-modified terminal or anion-modified PVA having an anionic group. PVA obtained by hydrolyzing vinyl acetate preferably has an average degree of polymerization of 300 or more, more preferably 1000 to 5000. The saponification degree is preferably from 70 to 100%, particularly preferably from 80 to 99.5%. When the ink absorbing layer is a void type, the mass ratio of the hydrophilic polymer to the inorganic or organic fine particles is usually from 1:10 to 1: 3, particularly preferably from 1: 8 to 1: 5.
[0086]
When the void layer contains a hydrophilic polymer, it is preferable to add a hardening agent in order to improve the film forming property of the film and increase the water resistance and strength of the film. As the hardener, generally, a compound having a group capable of reacting with the hydrophilic polymer or a compound which promotes a reaction between different groups of the hydrophilic polymer is preferable, and depending on the type of the hydrophilic polymer, It is appropriately selected and used. Specific examples of the hardener include, for example, epoxy hardeners (diglycidylethyl ether, ethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-diglycidylcyclohexane, N, N-diglycidyl) -4-glycidyloxyaniline, sorbitol polyglycidyl ether, glycerol polyglycidyl ether, etc.), aldehyde hardeners (formaldehyde, glyoxal, etc.), active halogen hardeners (2,4-dichloro-6-hydroxy-1, 3,5-triazine, etc.), active vinyl compounds (1,3,5-trisacryloyl-hexahydro-s-triazine, bisvinylsulfonylmethyl ether, etc.), isocyanate hardeners (toluylene diisocyanate, diphenylmethane diisocyanate) Over preparative etc.), boric acid, borates, borax, alum, and the like. When PVA is used as the hydrophilic polymer, it is preferable to use a hardening agent selected from boric acid, borate and epoxy hardening agents. The amount of the hardener used varies depending on the type of the hydrophilic polymer, the type of the hardener, the type of the silica fine particles, the ratio to the hydrophilic polymer, and the like, but is usually 5 to 500 mg, preferably 10 to 10 g per 1 g of the hydrophilic polymer. ３００300 mg. Also, a plurality of types of hardeners can be used in combination.
[0087]
Various additives other than those described above can be added to the ink absorbing layer of the recording medium. Above all, a cationic mordant is preferable for improving water resistance and moisture resistance after printing. In the present invention, the surface zeta potential of the recording medium can be controlled by appropriately selecting the type and amount of the cationic mordant.
[0088]
As the cationic mordant, a polymer mordant having a primary to tertiary amino group and a quaternary ammonium group is preferably used, but the discoloration and deterioration of light resistance with time are small, and the mordant ability of the dye is sufficiently high. Therefore, a polymer mordant having a quaternary ammonium base is preferred. Preferred polymer mordants are obtained as a homopolymer of the above-mentioned monomer having a quaternary ammonium salt group, as a copolymer with other monomers, or as a condensation polymer. Specific examples of the cationic mordant are described, for example, in "Inkjet Printer Technology and Materials", page 268 (published by CMC Corporation, 1998).
[0089]
Other than the above, for example, ultraviolet absorbers described in JP-A-57-74193, JP-A-57-87988 and JP-A-62-261476, JP-A-57-74192, JP-A-57-87989 and JP-A-60-72785. JP-A-61-146591, JP-A-1-95091 and JP-A-3-13376, various anionic, cationic or nonionic surfactants, JP-A-59-42993 and JP-A-59-42993. Nos. 52689, 62-280069, 61-242871, JP-A-4-219266, and the like, lubricants such as fluorescent whitening agents, defoamers, diethylene glycol, preservatives, thickeners, and antistatic agents. And various other known additives.
[0090]
In the recording medium of the present invention, the glossiness of the recording surface is preferably 40 to 80% as measured by a 75-degree specular glossiness according to JIS Z8741. The smaller the glossiness, the lower the sharpness of the recorded image is likely to be. Incidentally, the glossiness is preferably within the above range when measured at 75 degrees in the present invention, but generally becomes a lower value when measured at a lower angle, for example, 60 degrees or 45 degrees. is there.
[0091]
In the recording medium of the present invention, the pH of the recording surface is preferably from 3.5 to 8.0. When the film surface has a specific pH, the water resistance of the recorded image is improved. Here, the film surface pH is defined as J.I. TAPPI paper pulp test method No. 49 refers to the surface pH measured after 30 seconds using distilled water according to the method described in No. 49.
[0092]
The recording medium of the present invention can be produced by applying a coating liquid for forming an ink absorbing layer to the support. Here, it is preferable that the inorganic fine particles preferably used in the ink absorbing layer are sufficiently dispersed in a dispersion medium and then used as a coating liquid. The method for dispersing the inorganic fine particles preferably includes a preliminary dispersion step and a main dispersion step. Examples of the dispersion method that can be used include a high-speed stirring disperser, an ultrasonic disperser, a roller mill type, a kneader type, and a pin mixer type. And a high-pressure homogenizer, a wet media type pulverizer (sand mill, ball mill) and the like. The dispersion medium is not particularly limited, but is preferably an aqueous medium. The aqueous medium preferably contains the cationic mordant and the hardener in addition to water.
[0093]
Further, the hydrophilic polymer and various additives may be added in advance to the dispersion medium or the dispersion after dispersing the inorganic fine particles. For example, various nonionic or cationic surfactants, defoaming agents, nonionic Hydrophilic polymers (polyvinyl alcohol, polyvinyl pyrrolidone, polyethylene oxide, polyacrylamide, various sugars, gelatin, pullulan, etc.), nonionic or cationic latex dispersions, water-miscible organic solvents (ethyl acetate, methanol, ethanol , Isopropanol, n-propanol, acetone, etc.), inorganic salts, pH adjusters and the like can be used as needed. The recording medium of the present invention can be manufactured by applying a coating liquid comprising such a constituent material to the support.
[0094]
In applying the ink absorbing layer to the support, it is preferable to provide a corona discharge treatment or an undercoat layer on the support for the purpose of increasing the adhesive strength between the surface and the coating layer. The undercoat layer is provided with a hydrophilic polymer such as gelatin or polyvinyl alcohol, if necessary, in combination with a curing agent. The preferred thickness of the undercoat layer is in the range of 0.01 to 1 μm.
[0095]
When the ink jet recording medium of the present invention is used for recording only on one side, various methods are used to prevent curl on the side opposite to the side having the ink absorbing layer and further improve sticking and ink transfer when superimposed immediately after printing. Types of back layers can be provided. Although the configuration of the back layer varies depending on the type and thickness of the support and the configuration and thickness of the front side, generally, a hydrophilic binder or a hydrophobic binder is used.
[0096]
The thickness of the back layer is usually in the range of 0.1 to 10 μm. The surface of the back layer can be roughened to prevent "sticking" with other recording media, to improve writing properties, and to improve transportability in an ink jet recording apparatus. Organic or inorganic fine particles having a particle size of 0.5 to 20 μm are preferably used for this purpose. These back layers may be provided in advance, or may be provided after applying the ink absorbing layer on the opposite side.
[0097]
The coating method of the ink absorbing layer is preferably a roll coating method, a rod bar coating method, an air knife coating method, a spray coating method, a curtain coating method, or an extrusion coating method using a hopper described in US Pat. No. 2,681,294. Used. When a polyolefin resin-coated paper is used as the support, it is preferable that the drying be performed in a range of about 0 to 80 ° C. If the temperature is higher than 80 ° C., the polyolefin resin is softened to make it difficult to convey, or the gloss of the recording layer surface becomes uneven. Preferred drying temperatures are from 0 to 60C.
[0098]
After drying, the surfactant, the ultraviolet absorber, the anti-fading agent, the hardener, the cationic mordant, the antifoaming agent, the fluorescent brightener, the lubricant, the preservative, the thickener, etc. Alternatively, a known various additive-containing solution may be overcoated. In the present invention, the surface zeta potential can be controlled by the overcoat. Examples of the surfactant include an anionic surfactant, a cationic surfactant, an amphoteric surfactant, and a nonionic surfactant. Among them, the anionic surfactant or the cationic surfactant is used alone. Or a combination thereof. Inorganic particles and / or organic particles can also be added to the overcoat coating liquid. Light inorganic calcium carbonate, heavy calcium carbonate, magnesium carbonate, kaolin, clay, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc hydroxide, zinc sulfide, zinc carbonate, hydrotalcite, aluminum silicate White inorganic pigments such as diatomaceous earth, calcium silicate, magnesium silicate, synthetic amorphous silica, colloidal silica, alumina, colloidal alumina, pseudoboehmite, aluminum hydroxide, lithopone, zeolite, and magnesium hydroxide. Examples of the organic particles include an acrylic resin, a urea resin, a melamine resin, a phenol resin, and a styrene resin. The method of providing the overcoat layer on the ink absorbing layer is not particularly limited, and may be provided by a conventionally known coating machine or printing machine such as a bar coater, an air knife coater, a blade coater, and a curtain coater. it can. The coating amount of the overcoat layer does not need to be increased unnecessarily as long as the intended performance is satisfied.²Is preferably used.
[0099]
Next, the recording liquid in the present invention will be described. The recording liquid (ink) according to the invention is characterized in that the zeta potential is negative or positive. The zeta potential of the recording liquid can be controlled by the additives used and the like, resulting in excellent storage stability. The zeta potential of the recording solution can be measured by a known method using a commercially available device.
[0100]
In the inkjet recording method of the present invention, the zeta potential of the recording liquid is preferably from -90 mV to -10 mV, more preferably from -60 mV to -20 mV. As a result of intensive studies by the present inventors, it has been found that recording with a recording liquid in which the zeta potential is controlled in such a range exhibits particularly excellent color density and fixability. In particular, there was a tendency that the ink fixability was excellent. Although the reason is not clear, when a negatively charged inkjet recording liquid is discharged onto the recording surface of the recording medium, the image density and the ink fixing property are improved by a moderate interaction between the recording liquid and the recording medium surface. it is conceivable that.
[0101]
In the inkjet recording method of the present invention, the zeta potential of the recording liquid is preferably from +10 mV to +90 mV, more preferably from +20 mV to +60 mV. As a result of intensive studies by the present inventors, it has been found that recording with a recording liquid in which the zeta potential is controlled in such a range exhibits particularly excellent color density and fixability. In particular, there was a tendency that the image density was excellent. Although the reason is not clear, when the positively charged inkjet recording liquid is ejected onto the recording surface of the recording medium, the image density and the ink fixing property are improved by a moderate interaction between the recording liquid and the recording medium surface. it is conceivable that.
[0102]
The recording liquid is not particularly limited, but usually comprises a coloring material, a liquid medium, and other additives. As the coloring material used in the recording liquid, known water-soluble dyes such as oily dyes, disperse dyes, direct dyes, acid dyes, basic dyes, reactive dyes and food dyes used in ink jet recording can be used. Further, conventionally known organic and inorganic pigments can be used. For example, azo pigments such as azo lakes, insoluble azo pigments, condensed azo pigments, and chelated azo pigments; and phthalocyanine pigments, perylene and perylene pigments; Dye lakes such as cyclic pigments, basic dye lakes, and acid dye lakes; organic pigments such as nitro pigments, nitroso pigments, aniline black and daylight fluorescent pigments; and inorganic pigments such as carbon black. Further, colored resin fine particles made of a polymer containing a coloring material can be used.
[0103]
As a liquid medium for the recording liquid, an aqueous medium is preferable, and in order to prevent the coloring material from depositing when the recording liquid is dried and to prevent clogging at the nozzle tip and the ink supply path, the boiling point is usually about 120 ° C. Thus, a high-boiling organic solvent that is liquid at room temperature is added. The high-boiling organic solvent needs to have an action of preventing solid components such as coloring materials from being precipitated when water evaporates and generating coarse precipitates. It is required to have pressure. In addition, it is necessary to have high miscibility with water. Examples of high-boiling organic solvents used for such purposes include, for example, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, glycerin, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, glycerin monomethyl ether, 2,3-butanetriol, 1,2,4-butanetriol, 1,2,4-pentanetriol, 1,2,6-hexanetriol, thiodiglycol, triethanolamine, polyethylene glycol (average molecular weight is about 300 or less). In addition to the above, dimethylformamide, N-methylpyrrolidone and the like can also be used. Among these many high-boiling organic solvents, polyhydric alcohols such as diethylene glycol, triethanolamine, glycerin and triethanolamine, and lower alkyl ethers of polyhydric alcohols such as triethylene glycol monobutyl ether are preferred.
[0104]
Other additives contained in the recording liquid include, for example, a pH adjuster, a sequestering agent, a fungicide, a viscosity adjuster, a surface tension adjuster, a wetting agent, a surfactant, and a rust inhibitor. .
[0105]
The recording liquid is 2.5 × 10 5 at 25 ° C. for the purpose of improving the wettability to the recording medium and stabilizing the ejection from the ink jet nozzle.^-4~ 5.0 × 10^-4It preferably has a surface tension in the range of N / cm. The viscosity of the recording liquid is 2 × 10 5 at 25 ° C.^-3-10 × 10^-3Pa · s is preferred.
[0106]
Next, a recording liquid (ink) containing colored resin fine particles made of a polymer containing a coloring material will be described in detail.
[0107]
The colored resin fine particles referred to in the present invention are characterized in that they are colored resin fine particles composed of a polymer containing a coloring material, or colored resin fine particles composed of a polymer core and a polymer shell containing a coloring material. In particular, it is preferable to have a polymer core containing a coloring material and a polymer shell having a smaller coloring material content than the core.
[0108]
The polymer core mainly contains a coloring material and contributes to maintaining its fastness and color tone. On the other hand, the polymer shell contributes to increase the stability of the fine particles containing the coloring material as an ink suspension, further promotes fixing of the coloring material on a recording medium, prevents aggregation, and improves image quality. Contribute to improvement. In addition, it contributes to the robustness of the coloring material and the maintenance of the color tone.
[0109]
In the present invention, the content (concentration) of the coloring material in the shell is preferably 0.8 or less of the content of the coloring material in the core that is not cored / shelled. It is more preferably at most 0.5, particularly preferably at most 0.2.
[0110]
The coloring material content can be measured by a mass spectrometer such as TOF-SIMS. In TOF-SIMS, first, the total amount of ions having a mass number of 1 to 1000 is measured on the surface of each fine particle, and the coloring material content can be determined from the total amount of ions resulting from the dye therein. The color material content of each of the shell and the core / non-shelled core is compared. In TOF-SIMS, elemental analysis of several nm in the depth direction from the surface can be performed, so that core / shell fine particles as in the present invention can be analyzed.
[0111]
In the present invention, the colorant-containing resin fine particles used in the ink containing the colorant-containing polymer (resin) fine particles have a very large surface area per unit volume when the volume average particle diameter is 5 nm or less. The effect of enclosing inside is reduced. On the other hand, the particle diameter is preferably from 5 to 400 nm, and more preferably from 10 to 300 nm, from the viewpoint of easiness of clogging of the head, sedimentation in the ink, and stagnation stability.
[0112]
The volume average particle diameter can be determined by converting the circular average particle diameter obtained from the average value of the projected area (determined for at least 100 particles) of a transmission electron microscope (TEM) photograph into a spherical form. Furthermore, the coefficient of variation can be obtained by obtaining the volume average particle diameter and its standard deviation, and dividing the standard deviation by the volume average particle diameter. Further, the volume average particle diameter and the coefficient of variation can also be determined by using the dynamic light scattering method. For example, it can be determined using a laser particle size analysis system manufactured by Otsuka Electronics Co., Ltd. or a Zetasizer manufactured by Malvern.
[0113]
The larger the coefficient of variation of the particle diameter, the wider the distribution of the particle diameter. When the variation coefficient of the volume average particle diameter is 80% or more, “variation” is likely to occur in the surface physical properties between the particles. The “variation” of the surface physical properties is liable to cause agglomeration of particles and to cause clogging of the inkjet head. Further, the aggregation of the particles easily causes light scattering of the coloring material on the recording medium, and also tends to cause deterioration in image quality. The coefficient of variation is preferably 50% or less, and more preferably 30% or less.
[0114]
In the present invention, the amount of the polymer used in the shell is preferably 5 to 95% by mass of the total amount of the polymer. If the amount is less than 5% by mass, the thickness of the shell is insufficient, and a part of the core containing a large amount of the coloring material tends to appear on the particle surface. On the other hand, if the amount of the shell polymer is too large, the ability of the core to protect the coloring material is likely to be reduced. More preferably, the content is 10 to 90% by mass.
[0115]
The total amount of the coloring material is preferably 20 to 1000% by mass based on the total amount of the polymer. If the amount of the coloring material is too small as compared with the polymer, the image density after ejection will not increase, and if the amount of the coloring material is too large, sufficient protection of the polymer will not be obtained.
[0116]
As the core / shell in the present invention, a method of first preparing a polymer core containing a coloring material and then providing a polymer shell or a method of simultaneously providing a core shell can be considered.
[0117]
<Method of providing a shell after manufacturing the fine particle core>
The coloring material-containing polymer serving as the core can be prepared by various methods. For example, a method of dissolving an oil-soluble dye in a monomer, emulsifying in water, then encapsulating the dye in a polymer by polymerization, dissolving the polymer and coloring material in an organic solvent, removing the organic solvent after emulsification in water, There is a method of adding porous polymer fine particles to a dye solution, and adsorbing and impregnating the fine particles with the dye. The polymer shell can be provided by adding a water-soluble polymer dispersing agent to the aqueous suspension of the core polymer and adsorbing it, by gradually dropping the monomer and depositing it on the core surface simultaneously with polymerization, or by organic method. There is a method in which a polymer dissolved in a solvent is gradually dropped and adsorbed on the core surface simultaneously with the precipitation.
[0118]
Alternatively, the pigment can be kneaded with a polymer, then dispersed in an aqueous system to produce a polymer-coated pigment core, and then shelled by the above method.
[0119]
<Method of providing core and shell simultaneously when forming fine particles>
Either dissolving or dispersing the core polymer and colorant in the shell monomer after polymerization, suspending in water and then polymerizing, or emulsion polymerizing the solution while gradually dropping it into water containing activator micelles There are techniques to go. The monomer may be the core and the polymer may be the shell. Alternatively, there is a method of dissolving or dispersing a coloring material in a mixture of a monomer that can be a core and a monomer that can be a shell after polymerization, and performing suspension polymerization or emulsion polymerization.
[0120]
<Evaluation of core shell>
It is important to evaluate whether it is actually core-shelled. In the present invention, the analysis method is limited from the viewpoint of resolution because the individual particle diameter is very small, 500 nm or less. TEM, TOF-SIMS, or the like can be applied as an analysis method that meets such a purpose. When observing the core-shelled fine particles by TEM, the dispersion can be applied on a carbon support film, dried, and observed. The TEM observation image shows that the contrast difference is small only with the kind of polymer which is an organic substance, so that in order to evaluate whether or not it is core-shelled, fine particles were osmium tetroxide, ruthenium tetroxide, chlorosulfonic acid / uranyl acetate. , Silver sulfide or the like. The fine particles of only the core are stained and observed by TEM, and compared with those provided with a shell. Further, after mixing the fine particles provided with the shell and the fine particles not provided with the shell, dyeing is performed, and it is confirmed whether or not the ratio of the fine particles having different dyeing degrees matches the presence or absence of the shell.
[0121]
In a mass spectrometer such as TOF-SIMS, it is confirmed that by providing a shell on the particle surface, the amount of coloring material near the surface is smaller than when only the core is used. When there is an element not contained in the core shell polymer in the coloring material, it is possible to confirm whether a shell having a small coloring material content is provided by using the element as a probe.
[0122]
That is, the coloring material content is measured by TOF-SIMS on the surface of each fine particle, first measuring the total amount of ions having a mass number of 1 to 1000, and among the elements contained in the core-shell polymer contained in the dye, From the total amount of ions derived from By this method, the content of each dye can be measured by comparing the content of the coloring material with the content of the shell and the core that has not been subjected to core / shell formation. In TOF-SIMS, elemental analysis of several nm from the surface in the depth direction can be performed, so that core / shell fine particles as in the present invention can be analyzed.
[0123]
In the absence of such an element, the colorant content in the shell can be compared to that without the shell using a suitable dye.
[0124]
The core-shell formation can be more clearly observed by embedding the core-shell particles in an epoxy resin, preparing an ultrathin section with a microtome, and performing staining. As described above, when a polymer or a coloring material includes an element that can serve as a probe, the composition of the core-shell and the distribution amount of the coloring material to the core and the shell can also be estimated by TOF-SIMS or TEM.
[0125]
As described above, in the present invention, the content of the coloring material in the shell is preferably 0.8 or less of the content of the coloring material in the core that is not cored / shelled. It is more preferably 0.5 or less, particularly preferably 0.2 or less (of course, it may be 0 or a value as close as possible). As a result, the polymer core contains the main part of the coloring material, thereby contributing to maintaining its robustness and color tone, while the polymer shell maintains the stability of these fine particles containing the coloring material as an ink suspension. In addition to contributing to an increase in color, the fixation of the color material on the recording medium is prevented, aggregation is prevented, the image quality is improved, the color material is fastened, and the color tone is maintained.
[0126]
In order to obtain the required particle size, it is important to optimize the formulation and select an appropriate emulsification method. The formulation differs depending on the coloring material and polymer used, but a suspension in water is preferable. Therefore, it is generally necessary that the polymer constituting the shell has higher hydrophilicity than the polymer constituting the core. Further, the coloring material contained in the polymer constituting the shell is preferably smaller than that of the polymer constituting the core as described above, and the coloring material also needs to be lower in hydrophilicity than the polymer constituting the shell. . The hydrophilicity and the hydrophobicity can be estimated using, for example, a solubility parameter (SP). As for the solubility parameter, its value, measurement and calculation method can be referred to the description from page 675 of POLYMER HANDBOOK 4th edition (John Wiley & Sons, Inc.).
[0127]
The polymer used for the colorant-containing resin fine particles preferably has a number average molecular weight of 500 to 100,000, particularly 1,000 to 30,000, from the viewpoint of film formability after printing, its durability, and formability of the suspension.
[0128]
Various glass transition temperatures (Tg) of the polymer can be used, but it is preferable to use at least one polymer having a Tg of 10 ° C. or higher.
[0129]
In the present invention, all commonly known polymers can be used, but particularly preferred polymers are a polymer containing an acetal group as a main functional group, a polymer containing a carbonate group, and a polymer containing a hydroxyl group. And a polymer having an ester group. The above-mentioned polymer may have a substituent, and the substituent may have a linear, branched, or cyclic structure. Various polymers having the above functional group are commercially available, but can also be synthesized by a conventional method. These copolymers can also be obtained, for example, by introducing an epoxy group into one polymer molecule, and subsequently condensing with another polymer, or performing graft polymerization using light or radiation.
[0130]
Examples of the polymer containing an acetal as a main functional group include a polyvinyl butyral resin. For example, # 2000-L, # 3000-1, # 3000-2, # 3000-4, # 3000-K, # 4000-1, # 4000-2, # 5000-A, # 6000 manufactured by Denki Kagaku Kogyo Co., Ltd. -C, # 6000-EP, or BL-1, BL-1H, BL-2, BL-2H, BL-5, BL-10, BL-S, BL-SH, BX-10 manufactured by Sekisui Chemical Co., Ltd. , BX-L, BM-1, BM-2, BM-5, BM-S, BM-SH, BH-3, BH-6, BH-S, BX-1, BX-3, BX-5, KS -10, KS-1, KS-3 and KS-5.
[0131]
The resin is obtained as a derivative of PVA, and the degree of acetalization of hydroxyl groups of the original PVA is at most about 80 mol%, and usually about 50 to 80 mol%. In the case of polyvinyl butyral, a 1,1′-butylenedioxy group is formed as an acetal group. However, when the term “acetalization degree” is used, it does not refer to such a narrowly defined acetal. It means a general acetal group and refers to a compound having an acetal group formed from a compound having a hydroxyl group (in this case, PVA) and a compound having an aldehyde group (in this case, butanal). The hydroxyl group is not particularly limited, but is preferably contained at 10 to 40 mol%. The content of the acetyl group is not particularly limited, but is preferably 10 mol% or less. A polymer containing an acetal group as a main functional group means that at least 30 mol% or more of the oxygen atoms contained in the polymer form an acetal group.
[0132]
In addition, as a polymer containing an acetal group as a main functional group, an Iupital series manufactured by Mitsubishi Engineering-Plastics Corporation and the like can be used.
[0133]
Examples of the polymer containing a carbonate ester as a main functional group include a polycarbonate resin. For example, there are the Iupilon series and the Novalex series manufactured by Mitsubishi Engineering-Plastics Corporation. The Iupilone series is made from bisphenol A as a raw material, and its value varies depending on the measurement method, but those having various molecular weights can be used. In the NOVAREX series, those having a molecular weight of 20,000 to 30,000 and a Tg of around 150 ° C. can be used, but are not limited to these.
[0134]
A polymer containing a carbonate group as a main functional group means that at least 30 mol% or more of the oxygen atoms contained in the polymer contribute to the formation of the carbonate group.
[0135]
Examples of the polymer containing a hydroxyl group as a main functional group include PVA. Although the solubility of PVA in organic solvents is often low, PVA with a low saponification value increases the solubility in organic solvents. The highly water-soluble PVA can be used by adding it to the aqueous phase and adsorbing the polymer suspension after removing the organic solvent.
[0136]
As the PVA, commercially available ones can be used. For example, in addition to POVAL PVA-102, PVA-117, PVA-CSA, PVA-617, and PVA-505 manufactured by Kuraray Co., Ltd., PVA for sizing agents of special brands, hot melt KL-506, C-118, R-1130, M-205, MP-203, HL-12E, SK-5102 and the like can be used as PVA for molding and other functional polymers.
[0137]
The saponification degree is generally 50 mol% or more, but even if it is about 40 mol% like LM-10HD, it can be used. Other than such PVA, those having a hydroxyl group as a main functional group can be used, and those in which at least 20 mol% or more of the oxygen atoms contained in the polymer form a hydroxyl group can be used. .
[0138]
Examples of the polymer containing an ester group as a main functional group include methacrylic resin. Asahi Kasei Corporation's Delpet series 560F, 60N, 80N, LP-1, SR8500, SR6500 and the like can be used. The polymer containing an ester group as a main functional group means that at least 30 mol% or more of the oxygen atoms contained in the polymer form an ester group.
[0139]
These polymers may be used alone or in combination of two or more. If these polymers are contained in a mass ratio of 50% or more, other polymers or inorganic fillers may be contained.
[0140]
Although it is also preferable to use a copolymer of these polymers, for example, a polymer containing a hydroxyl group, as a technique of copolymerizing various polymers, a hydroxyl group is reacted with a monomer having an epoxy group such as glycidyl methacrylate, and then, It can be obtained by copolymerization with a methacrylate monomer by suspension polymerization.
[0141]
Next, the coloring material enclosed by the polymer will be described. Any coloring material that can be encapsulated by the polymer can be used without any particular limitation. Examples thereof include oily dyes, disperse dyes, direct dyes, acid dyes, and basic dyes. And a disperse dye.
[0142]
Particularly preferred specific examples of the disperse dye preferably used in the present invention are shown below, but are not limited thereto.
[0143]
C. I. Disperse Yellow 5, 42, 54, 64, 79, 82, 83, 93, 99, 100, 119, 122, 124, 126, 160, 184: 1, 186, 198, 199, 204, 224 and 237; . I. Disperse Orange 13, 29, 31: 1, 33, 49, 54, 55, 66, 73, 118, 119 and 163; I. Disperse Red 54, 60, 72, 73, 86, 88, 91, 92, 93, 111, 126, 127, 134, 135, 143, 145, 152, 153, 154, 159, 164, 167: 1, 177 , 181, 204, 206, 207, 221, 239, 240, 258, 277, 278, 283, 311, 323, 343, 348, 356 and 362; I. Disperse Bio Red 33; C.I. I. Disperse Blue 56, 60, 73, 87, 113, 128, 143, 148, 154, 158, 165, 165: 1, 165: 2, 176, 183, 185, 197, 198, 201, 214, 224, 225 C., 257, 266, 267, 287, 354, 358, 365 and 368; I. Disperse Green 6: 1 and 9 etc.
[0144]
On the other hand, the oil dye preferably used in the present invention is not limited to the following, but specific examples include, for example, C.I. I. Solvent Black 3, 7, 27, 29 and 34; C.I. I. Solvent Yellow 14, 16, 19, 29, 56 and 82; C.I. I. Solvent Red 1, 3, 8, 18, 24, 27, 43, 51, 72, 73, 132 and 218; I. Solvent Violet 3; I. Solvent Blue 2, 11, and 70; I. Solvent Green 3 and 7; and C.I. I. Solvent Orange 2 and the like.
[0145]
As the coloring material in the present invention, the following water-soluble dyes can also be used.
[0146]
Examples of the water-soluble dye that can be used include, for example, an azo dye, a methine dye, an azomethine dye, a xanthene dye, a quinone dye, a phthalocyanine dye, a triphenylmethane dye, a diphenylmethane dye, and the like. Show. However, it is not limited to these exemplified compounds.
[0147]
[C. I. Acid Yellow)
1, 3, 11, 17, 18, 19, 23, 25, 36, 38, 40, 42, 44, 49, 59, 61, 65, 67, 72, 73, 79, 99, 104, 110, 114, 116, 118, 121, 127, 129, 135, 137, 141, 143, 151, 155, 158, 159, 169, 176, 184, 193, 200, 204, 207, 215, 219, 220, 230, 232, 235, 241, 242, 246.
[0148]
[C. I. Acid orange)
3, 7, 8, 10, 19, 24, 51, 56, 67, 74, 80, 86, 87, 88, 89, 94, 95, 107, 108, 116, 122, 127, 140, 142, 144, 149, 152, 156, 162, 166, 168.
[0149]
[C. I. Acid Red)
1, 6, 8, 9, 13, 18, 27, 35, 37, 52, 54, 57, 73, 82, 88, 97, 106, 111, 114, 118, 119, 127, 131, 138, 143, 145, 151, 183, 195, 198, 211, 215, 217, 225, 226, 249, 251, 254, 256, 257, 260, 261, 265, 266, 274, 276, 277, 289, 296, 299, 315, 318, 336, 337, 357, 359, 361, 362, 364, 366, 399, 407, 415.
[0150]
[C. I. Acid Violet)
17, 19, 21, 42, 43, 47, 48, 49, 54, 66, 78, 90, 97, 102, 109, 126.
[0151]
[C. I. Acid Blue)
1, 7, 9, 15, 23, 25, 40, 62, 72, 74, 80, 83, 90, 92, 103, 104, 112, 113, 114, 120, 127, 128, 129, 138, 140, 142, 156, 158, 171, 182, 185, 193, 199, 201, 203, 204, 205, 207, 209, 220, 221 224, 225, 229, 230, 239, 249, 258, 260, 264, 278,279,280,284,290,296,298,300,317,324,333,335,338,342,350.
[0152]
[C. I. Acid Green)
9, 12, 16, 19, 20, 25, 27, 28, 40, 43, 56, 73, 81, 84, 104, 108, 109.
[0153]
[C. I. Acid Brown)
2, 4, 13, 14, 19, 28, 44, 123, 224, 226, 227, 248, 282, 283, 289, 294, 297, 298, 301, 355, 357, 413.
[0154]
[C. I. Acid Black)
1, 2, 3, 24, 26, 31, 50, 52, 58, 60, 63, 107, 109, 112, 119, 132, 140, 155, 172, 187, 188, 194, 207, 222.
[0155]
[C. I. Direct yellow)
8, 9, 10, 11, 12, 22, 27, 28, 39, 44, 50, 58, 86, 87, 98, 105, 106, 130, 132, 137, 142, 147, 153.
[0156]
[C. I. Direct orange)
6, 26, 27, 34, 39, 40, 46, 102, 105, 107, 118.
[0157]
[C. I. Direct red)
2, 4, 9, 23, 24, 31, 54, 62, 69, 79, 80, 81, 83, 84, 89, 95, 212, 224, 225, 226, 227, 239, 242, 243, 254.
[0158]
[C. I. (Direct violet)
9, 35, 51, 66, 94, 95.
[0159]
[C. I. Direct blue)
1, 15, 71, 76, 77, 78, 80, 86, 87, 90, 98, 106, 108, 160, 168, 189, 192, 193, 199, 200, 201, 202, 203, 218, 225, 229,237,244,248,251,270,273,274,290,291.
[0160]
[C. I. Direct green)
26, 28, 59, 80, 85.
[0161]
[C. I. Direct brown)
44, 106, 115, 195, 209, 210, 222, 223
[C. I. Direct black].
[0162]
17, 19, 22, 32, 51, 62, 108, 112, 113, 117, 118, 132, 146, 154, 159, 169.
[0163]
[C. I. Basic Yellow)
1, 2, 11, 13, 15, 19, 21, 28, 29, 32, 36, 40, 41, 45, 51, 63, 67, 70, 73, 91.
[0164]
[C. I. (Basic orange)
2, 21, 22.
[0165]
[C. I. (Basic Red)
1, 2, 12, 13, 14, 15, 18, 23, 24, 27, 29, 35, 36, 39, 46, 51, 52, 69, 70, 73, 82, 109.
[0166]
[C. I. (Basic violet)
1, 3, 7, 10, 11, 15, 16, 21, 27, 39.
[0167]
[C. I. (Basic blue)
1, 3, 7, 9, 21, 22, 26, 41, 45, 47, 52, 54, 65, 69, 75, 77, 92, 100, 105, 117, 124, 129, 147, 151.
[0168]
[C. I. Basic green)
1,4.
[0169]
[C. I. (Basic Brown)
One.
[0170]
[C. I. Reactive Yellow)
2, 3, 7, 15, 17, 18, 22, 23, 24, 25, 27, 37, 39, 42, 57, 69, 76, 81, 84, 85, 86, 87, 92, 95, 102, 105,111,125,135,136,137,142,143,145,151,160,161,165,167,168,175,176.
[0171]
[C. I. (Reactive orange)
1, 4, 5, 7, 11, 12, 13, 15, 16, 20, 30, 35, 56, 64, 67, 69, 70, 72, 74, 82, 84, 86, 87, 91, 92, 93, 95, 107.
[0172]
[C. I. Reactive Red)
2, 3, 5, 8, 11, 21, 22, 23, 24, 28, 29, 31, 33, 35, 43, 45, 49, 55, 56, 58, 65, 66, 78, 83, 84, 106, 111, 112, 113, 114, 116, 120, 123, 124, 128, 130, 136, 141, 147, 158, 159, 171, 174, 180, 183, 184, 187, 190, 193, 194, 195, 198, 218, 220, 222, 223, 228, 235.
[0173]
[C. I. (Reactive violet)
1, 2, 4, 5, 6, 22, 23, 33, 36, 38.
[0174]
[C. I. Reactive Blue)
2, 3, 4, 5, 7, 13, 14, 15, 19, 21, 25, 27, 28, 29, 38, 39, 41, 49, 50, 52, 63, 69, 71, 72, 77, 79, 89, 104, 109, 112, 113, 114, 116, 119, 120, 122, 137, 140, 143, 147, 160, 161, 162, 163, 168, 171, 176, 182, 184, 191, 194, 195, 198, 203, 204, 207, 209, 211, 214, 220, 221, 222, 231, 235, 236.
[0175]
[C. I. Reactive green)
8, 12, 15, 19, 21.
[0176]
[C. I. Reactive Brown)
2, 7, 9, 10, 11, 17, 18, 19, 21, 23, 31, 37, 43, 46.
[0177]
[C. I. Reactive Black)
5, 8, 13, 14, 31, 34, 39.
[0178]
These dyes described above are described in “Dyeing Notebook 21st Edition” (published by Shisensensha) and the like. Of these water-soluble dyes, phthalocyanine dyes are preferred.
[0179]
Examples of the phthalocyanine dye include unsubstituted dyes and dyes having a central element, and examples of the central element include metal and non-metallic dyes, preferably copper, and more preferably C.I. I. Direct Blue 199.
[0180]
It is also possible to use a pigment insoluble in water or various organic solvents.
As the pigment that can be used in the present invention, conventionally known organic and inorganic pigments can be used. For example, azo pigments such as azo lakes, insoluble azo pigments, condensed azo pigments, and chelated azo pigments; and phthalocyanine pigments, perylene and perylene pigments; Dye lakes such as cyclic pigments, basic dye lakes, and acid dye lakes; organic pigments such as nitro pigments, nitroso pigments, aniline black and daylight fluorescent pigments; and inorganic pigments such as carbon black.
[0181]
Specific organic pigments preferably used in the present invention are exemplified below.
Pigments for magenta or red include C.I. I. Pigment Red 2, C.I. I. Pigment Red 3, C.I. I. Pigment Red 5, C.I. I. Pigment Red 6, C.I. I. Pigment Red 7, C.I. I. Pigment Red 15, C.I. I. Pigment Red 16, C.I. I. Pigment Red 48: 1, C.I. I. Pigment Red 53: 1, C.I. I. Pigment Red 57: 1, C.I. I. Pigment Red 122, C.I. I. Pigment Red 123, C.I. I. Pigment Red 139, C.I. I. Pigment Red 144, C.I. I. Pigment Red 149, C.I. I. Pigment Red 166, C.I. I. Pigment Red 177, C.I. I. Pigment Red 178, C.I. I. Pigment Red 222 and the like.
[0182]
Examples of orange or yellow pigments include C.I. I. Pigment Orange 31, C.I. I. Pigment Orange 43, C.I. I. Pigment Yellow 12, C.I. I. Pigment Yellow 13, C.I. I. Pigment Yellow 14, C.I. I. Pigment Yellow 15, C.I. I. Pigment Yellow 17, C.I. I. Pigment Yellow 93, C.I. I. Pigment Yellow 94, C.I. I. Pigment Yellow 138 and the like.
[0183]
Examples of green or cyan pigments include C.I. I. Pigment Blue 15, C.I. I. Pigment Blue 15: 2, C.I. I. Pigment Blue 15: 3, C.I. I. Pigment Blue 16, C.I. I. Pigment Blue 60, C.I. I. Pigment Green 7 etc.
[0184]
As the coloring material, metal complex dyes as disclosed in JP-A-9-277693, JP-A-10-20559, and JP-A-10-30061 can also be used. For example, a dye represented by the following formula (1) or (2) described in JP-A-10-20559 can be used.
[0185]
Embedded image

[0186]
In the general formula (1), X¹Represents a group of atoms having a structure capable of forming at least a bidentate coordination bond with a metal ion;¹Is an aromatic hydrocarbon ring, a 5- to 6-membered heterocyclic ring or -L⁴= Y²And Y²Represents a nitrogen-containing 5- to 6-membered heterocyclic ring. L¹, L⁴Represents a substituted or unsubstituted methine group and a nitrogen atom;², L³Represents a substituted or unsubstituted methine group. M represents a metal ion, X¹And at least a bidentate coordination bond with the group of atoms formed by m represents an integer of 0, 1, 2 or 3, and n1 represents an integer of 1, 2 or 3.
[0187]
In the general formula (2), X³, Y³, M³And n2 are respectively the above X¹, Y¹, M and n1.
[0188]
Specific examples of the dyes represented by the general formulas (1) and (2) are described as D-1 to D-70 in paragraphs “0043” to “0056” of JP-A-10-20559.
[0189]
The colorant-containing polymer (resin) fine particles referred to in the present invention are preferably incorporated in the ink in which the colored resin fine particles are dispersed in an amount of 0.5 to 50% by mass, more preferably 0.5 to 30% by mass, as the polymer amount. More preferably, If the blending amount of the polymer is less than 0.5% by mass, the ability to protect the coloring material is not sufficient, and if it exceeds 50% by mass, the storage stability of the suspension as ink deteriorates, Clogging of the printer head may occur due to thickening of the ink and aggregation of the suspension caused by ink evaporation.
[0190]
On the other hand, the coloring material is preferably contained in the ink in an amount of 1 to 30% by mass, more preferably 1.5 to 25% by mass. If the amount of the coloring material is less than 1% by mass, the print density is insufficient, and if it exceeds 30% by mass, the stability over time of the suspension decreases, and the particle size tends to increase due to aggregation and the like.
[0191]
The recording liquid (ink) containing the colored resin fine particles made of the polymer containing the coloring material referred to in the present invention is preferably made of water as a medium, and is composed of a polymer suspension enclosing the coloring material. Various conventionally known additives, for example, wetting agents such as polyhydric alcohols, dispersants, antifoaming agents such as silicones, fungicides such as chloromethylphenols, and / or chelates such as EDTA (ethylenediaminetetraacetic acid). And an oxygen absorbent such as a sulfite.
[0192]
Examples of the wetting agent include ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, glycerin, diethylene glycol diethyl ether, diethylene glycol monobutyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and ethylene glycol monoethyl ether. Polyhydric alcohols such as butyl ether, methyl carbitol, ethyl carbitol, butyl carbitol, ethyl carbitol acetate, diethyl carbitol, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, propylene glycol monomethyl ether, and ethers and acetates thereof , N-methyl-2 Pyrrolidone, 1,3-dimethylimidazolidinone, triethanolamine, formamide, nitrogen-containing compounds such as dimethyl formamide, may be used one or more dimethyl monkey sulfoxide.
[0193]
The amount of these wetting agents is not particularly limited, but preferably 0.1 to 50% by mass, more preferably 0.1 to 30% by mass, in the ink.
[0194]
The dispersant is not particularly limited, but preferably has an HLB value of 8 to 18 from the viewpoint of exhibiting the effect as the dispersant and having the effect of suppressing an increase in the particle diameter of the suspension. Commercial products can also be used as dispersants. Examples of such commercially available products include Kao Corporation's dispersant Demol SNB, MS, N, SSL, ST, P.
[0195]
The amount of the dispersant is not particularly limited, but is preferably 0.01 to 10% by mass in the ink in which the colored resin fine particles are dispersed. If the amount is less than 0.01% by mass, it may be difficult to reduce the particle size of the suspension. If the amount is more than 10% by mass, the particle size of the suspension may increase or the stability of the suspension may decrease, resulting in gelation. There is.
[0196]
As the defoaming agent, a commercially available product can be used without any particular limitation. As such commercially available products, for example, KF96, 66, 69, KS68, 604, 607A, 602, 603, KM73, 73A, 73E, 72, 72A, 72C, 72F, 82F, 70, 71 manufactured by Shin-Etsu Silicone Co., Ltd. 75, 80, 83A, 85, 89, 90, 68-1F, 68-2F and the like.
[0197]
The amount of these compounds is not particularly limited, but is preferably 0.001 to 2% by mass in the ink in which the colored resin fine particles are dispersed. If the amount is less than 0.001% by mass, bubbles are easily generated at the time of preparing the ink, and it is difficult to remove small bubbles in the ink. If the amount exceeds 2% by mass, the generation of bubbles is suppressed. In this case, repelling may occur in the ink and the print quality may be degraded.
[0198]
Next, a method for producing a recording liquid (ink) in which colored resin fine particles are dispersed will be described. The ink of the present invention can be produced by various emulsification methods, and various methods can be used as the emulsification method. Examples of these are summarized in, for example, page 86 of “Advances and Applications of Functional Emulsifiers / Emulsification Techniques, published by CMC Corporation”. In the present invention, it is particularly preferable to use an emulsifying and dispersing apparatus using ultrasonic waves, high-speed rotational shearing, and high pressure.
[0199]
In emulsification and dispersion by ultrasonic waves, two types, a so-called batch type and a continuous type, can be used. The batch method is suitable for producing a relatively small amount of sample, and the continuous method is suitable for producing a large amount of sample. In the continuous system, for example, an apparatus such as UH-600SR (manufactured by SMT Corporation) can be used. In the case of such a continuous system, the irradiation time of the ultrasonic wave can be obtained by (dispersion chamber volume / flow rate × circulation number). When there are a plurality of ultrasonic irradiation devices, the ultrasonic irradiation devices are obtained as the sum of the respective irradiation times. The irradiation time of the ultrasonic wave is practically 10,000 seconds or less. If a time longer than 10,000 seconds is required, the load on the process is large, and in practice, it is necessary to shorten the emulsification dispersion time 37 by reselecting an emulsifier or the like. Therefore, no time exceeding 10,000 seconds is required. More preferably, it is 10 to 2,000 seconds.
[0200]
Examples of the emulsifying and dispersing apparatus using high-speed rotational shear include disperser mixers as described on pages 255 to 256 of "Advances and Applications of Functional Emulsifiers / Emulsification Techniques" (supra). For example, a homomixer such as an ultramixer described on page 256 can be used. These types can be properly used depending on the liquid viscosity at the time of emulsification and dispersion. In an emulsifying and dispersing machine using high-speed rotation shearing, the rotation speed of the stirring blade is important. In the case of an apparatus having a stator, the clearance between the stirring blade and the stator is usually about 0.5 mm and cannot be extremely narrow, so that the shearing force mainly depends on the peripheral speed of the stirring blade. If the peripheral speed is 5 to 150 m / sec, it can be used for emulsification and dispersion of the present invention. This is because, when the peripheral speed is low, it is often impossible to achieve a small particle size even if the emulsification time is extended, and it is necessary to extremely increase the performance of the motor to achieve 150 m / sec. More preferably, it is 20 to 100 m / sec.
[0201]
In emulsification and dispersion by high pressure, LAB2000 (manufactured by SMT Co.) can be used, but the emulsification / dispersion ability depends on the pressure applied to the sample. Pressure is 10⁴~ 5 × 10⁵The range of kPa is preferable. Further, emulsification / dispersion may be performed several times as necessary to obtain a target particle size. If the pressure is too low, the target particle size cannot be achieved in many cases even if emulsification and dispersion are performed many times.⁵In order to make the pressure kPa, a large load is applied to the apparatus, which is not practical. More preferably 5 × 10⁴~ 2 × 10⁵The range is kPa.
[0202]
These emulsifying / dispersing devices may be used alone, but may be used in combination as needed.
[0203]
Further, the ink of the present invention can be produced by so-called phase inversion emulsification in addition to using the above apparatus. Phase inversion emulsification means dissolving the polymer in an organic solvent such as an ester or ketone together with the dye, adding a neutralizing agent as needed to ionize the carboxyl groups in the polymer, and then adding an aqueous phase. And evaporating the organic solvent and inverting the phase to an aqueous system. After the phase inversion is completed, the system is heated under reduced pressure to remove the ester and ketone solvents and to remove a predetermined amount of water to disperse colored resin fine particles having a desired concentration. Is obtained.
[0204]
Next, the ink jet recording method of the present invention will be described. The method for inkjet recording using the recording liquid on the inkjet recording medium of the present invention is not particularly limited, and printing or an image can be obtained by using a piezo-type or thermal-type inkjet printer. it can. The details of the recording method are described, for example, in Trends of Inkjet Recording Technology (Edited by Koichi Nakamura, published on March 31, 1995, Japan Science Information Co., Ltd.). The inkjet head that can be used in the recording method of the present invention may be an on-demand type or a continuous type. The ink ejection method includes electro-mechanical conversion methods (single-cavity type, double-cavity type, bender type, piston type, shared mode type, shared wall type, etc.), and electro-thermal conversion methods (thermal inkjet type, Specific examples include a bubble jet (R) type, an electrostatic suction method (electric field control type, a slit jet type, etc.) and a discharge method (spark jet type, etc.). No problem.
[0205]
【Example】
Hereinafter, the present invention will be described specifically with reference to Examples, but embodiments of the present invention are not limited thereto.
[0206]
<Preparation of support>
Water content 6.5%, basis weight 170g / m²Was coated with a low-density polyethylene having a density of 0.92 to a thickness of 30 μm by a melt extrusion coating method. Next, a low-density polyethylene having a density of 0.92 containing 5.5% of anatase-type titanium oxide was applied by a melt extrusion method to a thickness of 35 μm on the front side to prepare a support having both surfaces coated with polyethylene.
[0207]
A corona discharge was applied to the front side to form a gelatin undercoat layer having a thickness of 0.3 g / m2.²After performing corona discharge on the back surface, the latex layer was formed to a thickness of 0.2 g / m2.²Was applied.
[0208]
<Preparation of titanium oxide dispersion liquid 1>
20 kg of titanium oxide having an average particle size of about 0.25 μm (W-10, manufactured by Ishihara Sangyo), 150 g of sodium tripolyphosphate having a pH of 7.5, 500 g of polyvinyl alcohol (PVA235, manufactured by Kuraray Co., Ltd.), and a cationic polymer ( P-1) 90 g of an aqueous solution containing 150 g of an antifoaming agent SN381 of 150 g and Sannobuko Co., Ltd. was added and dispersed with a high-pressure homogenizer (manufactured by Sanwa Kogyo Co., Ltd.). Liquid 1 was obtained.
[0209]
Embedded image

[0210]
<Preparation of optical brightener dispersion liquid 1>
400 g of an oil-soluble fluorescent whitening agent UVITEX-OB manufactured by Ciba-Geigy Co., Ltd. was heated and dissolved in 9000 g of diisodecyl phthalate and 12 L of ethyl acetate, and 3500 g of acid-treated gelatin and 0.8 kg of a cationic polymer (P-1) were dissolved. Was added to and mixed with 65 L of an aqueous solution containing 6 L of a 50% aqueous solution of saponin, emulsified and dispersed with a high-pressure homogenizer manufactured by Sanwa Kogyo Co., Ltd., and ethyl acetate was removed under reduced pressure. White agent dispersion liquid 1 was prepared.
[0211]
<Preparation of silica dispersion liquid 1>
As an aqueous medium (hereinafter referred to as liquid A),
80L of water
Boric acid 0.27kg
Borax 0.23kg
0.4L of 5% nitric acid
1.8L ethanol
Cationic polymer (P-1) (25% by mass aqueous solution) 5L
Were mixed and dissolved. 32 kg of precipitated silica (prepared by Tokuyama Corporation: trade name: T-32, average secondary particle size 1.5 μm: hereinafter referred to as T-32) was prepared and dispersed as follows to obtain dispersion liquid 1. . Solution A was supplied at a rate of 1.56 kg / min and T-32 at a rate of 0.44 kg / min as a disperser 1 to a flow jet mixer 300 (pin mixer type, manufactured by Koken Powtex, hereinafter referred to as FJM). Then, it was supplied to a fine flow mill FM-25 (a continuous high-speed stirring type disperser, manufactured by Taiyo Kiko Co., Ltd., hereinafter referred to as FM) as a disperser 2. Thereafter, LMK-4 (a continuous wet media type pulverizer, manufactured by Ashizawa, hereinafter referred to as LMK) was used as the disperser 3, and the dispersion liquid from the disperser 2 was 2.0 kg / min into the LMK using a mono pump. Supplied with FJM conditions: peripheral speed 25 m / sec, residence time 20 sec, FM conditions: peripheral speed 25 m / sec, residence time 0.15 sec, LMK conditions: bead diameter 0.5 mm zirconia, residence time 5 min, rotor rotation peripheral speed 11 m / sec. Thereafter, the dispersion obtained from LMK was filtered. The filter used was a profile manufactured by Pall Corporation. At this time, the average particle size of the silica was 210 nm. The average particle size is a value measured with a Zetasizer 1000HS manufactured by Malvern.
[0212]
<Preparation of silica dispersion 2>
The dispersion was prepared in the same manner as the silica dispersion 1, except that the cationic polymer (P-1) (25 mass% aqueous solution) was changed to 20 L. The average particle size was 220 nm.
[0213]
<Preparation of silica dispersion 3>
The dispersion was prepared in the same manner as the silica dispersion 1, except that the cationic polymer (P-1) (25 mass% aqueous solution) was changed to 30 L. The average particle size was 240 nm.
[0214]
<Preparation of silica dispersion 4>
Dispersion was carried out in the same manner as silica dispersion liquid 1 except that the silica was changed to gel method silica (trade name: AZ-204, manufactured by Nippon Silica Co., Ltd., average secondary particle size: 1.3 μm). The average particle size was 220 nm.
[0215]
<Preparation of silica dispersion 5>
Dispersion was carried out in the same manner as silica dispersion liquid 1 except that the silica was changed to fumed silica (trade name: A-300, manufactured by Nippon Aerosil Co., Ltd.) and the rotor rotation peripheral speed of LMK was set to 8 m / sec. The average particle size was 190 nm.
[0216]
<Preparation of silica dispersion 6>
The silica was changed to fumed silica (trade name: A-300, manufactured by Nippon Aerosil Co., Ltd.), the cationic polymer (P-1) (25 mass% aqueous solution) was set to 30 L, and the rotor rotation peripheral speed of LMK was set to 8 m / sec. The dispersion was performed in the same manner as in the silica dispersion 1 except that The average particle size was 200 nm.
[0217]
[Preparation of inkjet recording medium 1]
<Preparation of coating liquid>
The coating solutions for the first, second and third layers were prepared according to the following procedure.
[0218]
Coating solution for first layer
The following additives were sequentially mixed with 560 ml of a prepared dispersion prepared by adjusting the silica dispersion 1 such that the silica mass concentration of the dispersion became 10% at 40 ° C.
[0219]
Polyvinyl alcohol
0.6 ml of a 10% aqueous solution of (Kuraray Industries, Ltd .: PVA203)
Polyvinyl alcohol
150 ml of 5% aqueous solution of (Kuraray Industries Co., Ltd .: PVA235)
Polyvinyl alcohol
100 ml of 5% aqueous solution of (Kuraray Industries: PVA245)
Fluorescent brightener dispersion liquid 1 32ml
Titanium oxide dispersion 1 30ml
Latex emulsion (manufactured by Dai-ichi Kogyo Co., Ltd .: AE-803) 21 ml
Make up to 1000ml with pure water.
[0220]
Second layer coating solution
The following additives were sequentially mixed with 630 ml of a prepared dispersion prepared by adjusting the silica dispersion 1 such that the silica mass concentration of the dispersion became 10% at 40 ° C.
[0221]
Polyvinyl alcohol
0.6 ml of a 10% aqueous solution of (Kuraray Industries, Ltd .: PVA203)
Polyvinyl alcohol
150 ml of 5% aqueous solution of (Kuraray Industries Co., Ltd .: PVA235)
Polyvinyl alcohol
100 ml of 5% aqueous solution of (Kuraray Industries: PVA245)
Fluorescent brightener dispersion liquid 1 50ml
Make up to 1000ml with pure water.
[0222]
Coating solution for third layer
The following additives were sequentially mixed with 640 ml of a prepared dispersion prepared by preparing the silica dispersion 1 so that the silica mass concentration of the dispersion became 10% at 40 ° C.
[0223]
Polyvinyl alcohol
0.6 ml of a 10% aqueous solution of (Kuraray Industries, Ltd .: PVA203)
Polyvinyl alcohol
150 ml of 5% aqueous solution of (Kuraray Industries Co., Ltd .: PVA235)
Polyvinyl alcohol
100 ml of 5% aqueous solution of (Kuraray Industries: PVA245)
Silicon dispersion
(Toy Dow Corning Silicone Co., Ltd .: BY-22-839)
3.5ml
Saponin 50% aqueous solution 4ml
2 ml of 5% aqueous solution of fluorinated nonionic surfactant
Make up to 1000ml with pure water.
[0224]
<Application>
The coating solution obtained as described above is coated on the front side of the support coated on both sides with polyethylene such that a first layer (40 μm), a second layer (110 μm), and a third layer (30 μm) are formed in this order. Were simultaneously coated. The values in parentheses indicate the respective wet film thicknesses. Coating was performed simultaneously at 40 ° C. with a three-layer curtain coater at a temperature of 40 ° C., immediately after coating, cooled in a cooling zone maintained at 8 ° C. for 20 seconds, and then blown with a wind of 20 to 30 ° C. for 60 seconds, 45 seconds. 23 ° C. after drying for 60 seconds in a wind at 50 ° C. and 60 seconds in a wind at 50 ° C. (the film temperature in the constant rate drying area is 8 to 25 ° C., and the film temperature gradually increases in the decreasing rate drying area). The humidity was controlled at a relative humidity of 40 to 60%.
[0225]
Next, 2.0 g / m 2 of an isocyanate compound (a mixture of Coronate 3041 manufactured by Nippon Polyurethane Industry Co., Ltd. and Sumidur N3300 manufactured by Sumitomo Bayer Urethane Co., Ltd., 2: 8 (mass ratio)) dissolved in ethyl acetate was used.²To obtain an inkjet recording medium 1.
[0226]
[Production of inkjet recording media 2 to 8]
Inkjet recording media 2 to 6 were produced in the same manner as in the above inkjet recording medium 1 except that the dispersions were changed to silica dispersions 2 to 6. Further, inkjet recording media 7 and 8 were produced in the same manner as the inkjet recording medium 1 except that silica dispersions 3 and 6 were used and the isocyanate compound was not overcoated.
[0227]
Table 1 shows the silica dispersion, surface zeta potential, and 75 ° specular gloss of the obtained inkjet recording medium. The surface zeta potential of the recording medium was measured using a laser zeta electrometer ELS-8000 manufactured by Otsuka Electronics Co., Ltd. and a cell for a flat plate sample. Specifically, the electroosmotic flow was measured by using an aqueous solution of NaCl having a pH of 7.0 and a concentration of 10 mM as an electrolyte, and using polystyrene latex as monitor particles, and the electroosmotic flow was measured and analyzed. The gloss is a value obtained by measuring the gloss according to JIS Z 8741 at an incident angle of 75 ° and a light receiving angle of 75 ° using a VGS-1001DP type gloss meter manufactured by Nippon Denshoku Industries Co., Ltd.
[0228]
[Table 1]

[0229]
[Preparation of recording liquid 1 (dye-based)]
The components shown below were mixed, sufficiently stirred and dissolved, and then filtered through a 0.8 μm membrane filter to remove dust and coarse particles. Thus, a recording liquid 1 for inkjet was prepared. The zeta potential was +48 mV. The zeta potential of the recording solution was calculated using a laser zeta potentiometer ELS-8000 manufactured by Otsuka Electronics.
[0230]
C. I. Direct Blue 199 3% by mass
7% by mass of ethylene glycol
Diethylene glycol 10% by mass
Colloidal silica (Snowtex AK, manufactured by Nissan Chemical Industries, Ltd.) 3% by mass
Surfynol 465 (manufactured by Nissin Chemical Industry) 0.1% by mass
76.9% by mass of water
[Preparation of recording liquid 2 (dye-based)]
A recording liquid 2 for ink jet was prepared in the same manner except that the colloidal silica (Snowtex AK, manufactured by Nissan Chemical Industries, Ltd.) of the recording liquid 1 was changed to colloidal silica (Snowtex 20, manufactured by Nissan Chemical Industries, Ltd.). . The zeta potential was -51 mV.
[0231]
[Preparation of recording liquid 3 (pigment-based)]
A pigment dispersion was prepared using the following components, and a recording liquid was prepared using the dispersion.
[0232]
<Preparation of pigment dispersion>
C. I. Pigment Blue 15 10% by mass
Styrene-acrylic acid-ethyl acrylate copolymer
(Mass average molecular weight 5000) 1.5% by mass
Monoethanolamine 1% by mass
Diethylene glycol 5% by mass
82.5% by weight of water
After mixing the above components and performing premixing for 30 minutes, dispersion treatment was performed with a sand mill. Furthermore, centrifugation was performed to remove coarse particles to obtain a dispersion.
[0233]
Using the above pigment dispersion, the following components were mixed, sufficiently stirred, and filtered through a 0.8 μm membrane filter to remove dust and coarse particles, thereby preparing a recording liquid 3 for inkjet. The zeta potential was -32 mV.
[0234]
30% by mass of the above pigment dispersion
Glycerin 10% by mass
Ethylene glycol 5% by mass
Ethyl alcohol 2% by mass
Water 53% by mass
[Preparation of recording liquid 4 (pigment-based)]
A recording liquid 4 for inkjet was prepared in the same manner except that 5% by mass of water of the recording liquid 3 was changed to colloidal silica (Snowtex AK, manufactured by Nissan Chemical Industries, Ltd.). The zeta potential was +25 mV.
[0235]
[Preparation of recording liquids 5 to 7 (colored resin fine particle system)]
<Preparation of Colored Resin Fine Particle Dispersion 5>
As a polymer, 15 g of polyvinyl butyral (BL-S manufactured by Sekisui Chemical Co., Ltd., average degree of polymerization: 350), 5 g of John Krill 67 (manufactured by Johnson Polymer), and as a coloring material, a cyan dye (CI Solvent Blue 70) ) 10 g and 150 g of ethyl acetate were put into a separable flask, and N₂After stirring, the above polymers and dyes were completely dissolved by stirring. Next, 150 g of an aqueous solution containing 3 g of sodium hydroxide and 3 g of sodium lauryl sulfate necessary for neutralizing Joncryl 67 is dropped and stirred, and then, using an ultrasonic dispersing machine (UH-150 type, manufactured by SMT Co., Ltd.). The emulsion was emulsified at 70 ° C. for 300 seconds. Thereafter, ethyl acetate was removed under reduced pressure to obtain a colored resin fine particle dispersion 5 impregnated with the dye. The shell polymer in this colored resin fine particle dispersion liquid 5 is Joncryl 67, and its ratio to the total polymer is 25% by mass.
[0236]
<Preparation of Colored Resin Fine Particle Dispersion 6>
15 g of polyvinyl butyral (BL-S manufactured by Sekisui Chemical Co., Ltd., average degree of polymerization: 350) as a polymer, 10 g of a cyan dye (CI solvent blue 70) as a coloring material, and 150 g of ethyl acetate are put in a separable flask. , N inside the flask₂After stirring, the polymer and the dye were completely dissolved by stirring. Then, 150 g of an aqueous solution containing 3 g of polyvinyl alcohol resin (MP-203, manufactured by Kuraray Co., Ltd.) and 3 g of sodium lauryl sulfate was dropped and stirred, and then an ultrasonic disperser (UH-150, manufactured by SMT Corporation) was used. And emulsified at 70 ° C. for 300 seconds. Thereafter, the ethyl acetate was removed under reduced pressure to obtain a colored resin particle dispersion 6 impregnated with the dye. The shell polymer in this colored resin fine particle dispersion 6 is MP-203, and the ratio to the total polymer is 16.7% by mass.
[0237]
<Preparation of Colored Resin Fine Particle Dispersion 7>
A colored resin particle dispersion 7 was prepared in the same manner as in the preparation of the colored resin particle dispersion 5, except that John Krill 67 and sodium hydroxide were not added.
[0238]
Using the above colored resin fine particle dispersions 5 to 7, the following components were mixed, sufficiently stirred, and filtered through a 0.8 μm membrane filter to remove dust and coarse particles. 5-7 were prepared.
[0239]
Colored resin fine particle dispersion liquid 5 to 7 69.9% by mass
15% by mass of ethylene glycol
Glycerin 15% by mass
Surfynol 465 (manufactured by Nissin Chemical Industry) 0.1% by mass
<Measurement of each characteristic value of recording liquid>
For the recording liquid containing the colored resin fine particles prepared as described above, the volume average particle diameter, the coefficient of variation thereof, the confirmation of core-shell formation, the color material concentration ratio of the core and the shell, and the zeta potential were calculated and obtained according to the following methods. Table 2 shows the results.
[0240]
The volume average particle size was measured using a laser particle size analysis system manufactured by Otsuka Electronics.
The circular conversion average particle diameter obtained from the average value of the projected area of the TEM photograph was converted into a sphere, and the volume average particle diameter and its standard deviation were obtained.
[0241]
To confirm the core-shell structure, fix the ultrathin section of the suspension on a mesh with a carbon support film, and then₄, And each was compared with Comparative Example to confirm the degree of staining.
[0242]
The calculation of the coloring material content (density) ratio of the coloring material in the core / shell was performed as follows.
[0243]
The colored resin fine particles prepared on a Si-wafer are applied and dried, and using TRIFT-II manufactured by Physical Electronics Co., the mass intensity of the dye as a coloring material + the area intensity of 0.5 to 0.5 to 1000a. m. u. The color material content (concentration) ratio of the core and the shell was calculated by comparing this value with the core-only particles and the core / shell particles.
[0244]
Equipment name; TRIFT-II
Manufacturer: Physical Electronics
Primary ion; Ga⁺
Acceleration voltage: 15 kV
Measured mass range; 0.5-1000a. m. u.
Measurement area: 60 μm × 60 μm
Detected ion; positive secondary ion detection
Total time: 5 minutes
Measurement temperature; cooled with liquid nitrogen
Stage voltage: 3000V
The zeta potential was calculated using a laser zeta electrometer ELS-8000 manufactured by Otsuka Electronics.
[0245]
[Table 2]

[0246]
[Recording of inkjet image]
After the recording liquids 1 to 7 prepared as described above were stored in an ink jet cartridge, images were recorded on the recording media 1 to 8 produced in the combinations shown in Table 3 using a color ink jet printer PM800C (manufactured by Seiko Epson Corporation). As the output image, a wedge image in which the output density was divided into 16 levels from 0% to 100% (each density was output as a 3 cm × 3 cm patch) was recorded.
[0247]
[Evaluation of recorded image]
For each of the images recorded as described above, the maximum reflection density at an output density of 100% was evaluated. Further, the fixability (abrasion resistance) was evaluated according to the following method. Table 3 shows the results.
[0248]
<Fixability: Evaluation of scratch resistance>
A 19.6N load is applied to a plate (3 cm square) on which a patch portion having an output density of 100% of each of the output images is attached to a platen having flatness so that the image is on the surface and to which disinfecting gauze is attached. Was pressed against the image surface to rub the image surface for 100 round trips. The optical reflection densities of the images before and after rubbing were measured at three points, and the average value was determined. When the optical reflection density before rubbing was A and the optical reflection density after rubbing was B, the image remaining rate (%) was determined as follows, and this was used as a measure of scratch resistance.
[0249]
Image remaining rate (%) = B / A × 100
[0250]
[Table 3]

[0251]
As is clear from Table 3, the inkjet recording medium of the present invention and the inkjet recording method of recording with a recording liquid having a negative or positive zeta potential have excellent image density and ink fixability.
[0252]
【The invention's effect】
According to the present invention, an ink jet recording medium and an ink jet recording method excellent in image density and ink fixability can be provided.

Claims (12)

An ink jet recording medium characterized in that the surface zeta potential at pH 7 of the recording surface of the ink jet recording medium having at least one ink absorbing layer on a support is from +5 mV to +30 mV. 2. The ink jet recording medium according to claim 1, wherein the surface zeta potential is not less than +10 mV and not more than +25 mV. 3. An ink jet recording method, comprising: recording on the ink jet recording medium according to claim 1 using a recording liquid having a negative zeta potential. 4. The ink jet recording method according to claim 3, wherein the recording liquid contains a pigment as a coloring material. 4. The ink jet recording method according to claim 3, wherein the recording liquid contains colored resin fine particles made of a polymer containing a coloring material. 6. The ink jet recording method according to claim 5, wherein the colored resin fine particles are colored resin fine particles comprising a polymer core and a polymer shell containing a coloring material. The inkjet recording method according to any one of claims 3 to 6, wherein the zeta potential of the recording liquid is from -90 mV to -10 mV. 3. An ink jet recording method, comprising: recording on the ink jet recording medium according to claim 1 using a recording liquid having a positive zeta potential. The ink jet recording method according to claim 8, wherein the recording liquid contains a pigment as a coloring material. 9. The ink jet recording method according to claim 8, wherein the recording liquid contains colored resin fine particles made of a polymer containing a coloring material. The inkjet recording method according to claim 10, wherein the colored resin fine particles are colored resin fine particles comprising a polymer core and a polymer shell containing a coloring material. The inkjet recording method according to any one of claims 8 to 11, wherein the zeta potential of the recording liquid is not less than +10 mV and not more than +90 mV.