JP4501366B2 - Kneaded product for aqueous yellow pigment dispersion and method for producing aqueous yellow pigment dispersion and ink composition using the same - Google Patents

Description

【００６８】
また、同様に本実施例及び比較例に使用した樹脂S及びTは以下のものである。樹脂S：モノマー組成比において、スチレン／メタアクリル酸／アクリル酸＝77／13／10(質量比)であり、質量平均分子量12000、酸価152mgKOH/g、ガラス転移点107℃である樹脂。
樹脂T：モノマー組成比でスチレン／メタアクリル酸／アクリル酸＝77／13／10(質量比)とし、分子量が質量平均分子量で7500、酸価150mgKOH/g、ガラス転移点107℃である樹脂。
【００６９】
（実施例１）
下記組成の混合物を、容量50LのプラネタリーミキサーPLM-V-50V(株式会社井上製作所製)に仕込み、ジャケットを加温し、内容物温度が60℃になるまで低速(自転回転数：21rpm、公転回転数：14rpm)で混練を行い、内容物温度が60℃に達した後、高速(自転回転数：35rpm、公転回転数：24rpm)に切替、混練を継続した。
【００７０】
樹脂S 2500g
IRGAPHOR Yellow 8GCF (Pigment Yellow 128)
(チバスペシャリティーケミカルス株式会社製) 5000g
34質量%水酸化カリウム水溶液(KOH) 1118g
ジエチレングリコール 3000g
イオン交換水 1000g
【００７１】
高速への切替時のプラネタリーミキサー電流値は7Aであった。その後、混練を継続し、プラネタリーミキサーの最大電流値が12Aを示した。最大電流値を示してから30分後、プラネタリーミキサー電流値は8Aに低下し安定したこの状態で混練を3時間継続して混練物を得た。
続いて、撹拌槽内の混練物に、混練を継続しながらイオン交換水を13g／分で1000gのイオン交換水を加えた。その後、混練を継続しながら50g／分で4800gのイオン交換水を加えた。さらに、1500gのイオン交換水を加え、粘度調整物とし、取出した。
【００７２】
取り出した粘度調整物10.00kgに、ジエチレングリコール3514.4g、イオン交換水2184.8gを分散撹拌機で撹拌しながら少量づつ添加して、分散させた。さらに、ビーズミル(浅田鉄工製ナノミルNM-G2L)にて下記条件で分散を実施し、顔料分散液A1を得た。
【００７３】
分散条件
分散機 ナノミルNM-G2L(浅田鉄工製)
ビーズ φ0.3ｍｍジルコニアビーズ
ビーズ充填量 85%
冷却水温度 10℃
回転数 2660rpm (ディスク周速：12.5m/sec)
送液量 500g/min
なお、分散は上記条件で、1回分散機を通す(1パス)ことで行った。
顔料分散液A1は、固形分濃度25.4質量%、顔料濃度16.1質量%であった。
【００７４】
（比較例１）
実施例1において、34質量%水酸化カリウム水溶液の替わりにイオン交換水とすること以外は、実施例1と全く同様にしてプラネタリーミキサーを用いて、粘度調整物を得た。
このプラネタリーミキサーでの混練時の状態は、実施例1と異なり、明確な電流値の変化が無く、7〜8Aで推移した。
得られた粘度調整物10kgにジエチレングリコール3514.4g、34質量%水酸化カリウム水溶液561.2g、イオン交換水1749.2gを分散撹拌機で撹拌しながら少量づつ添加して、分散させた。さらに、実施例1と全く同様にしてビーズミルで分散を実施したが、分散機への送液圧力が上昇し、500ml/minでは送液できないため、30ml/minまで送液量を低下させ分散を実施し、顔料分散液B1を得た。
顔料分散液B1の固形分濃度は25.1質量%で、顔料濃度は15.9質量%であった。
【００７５】
（実施例２）
下記組成の混合物を、容量50LのプラネタリーミキサーPLM-V-50V(株式会社井上製作所製)に仕込み、ジャケットを加温し、内容物温度が60℃になるまで低速(自転回転数：21rpm、公転回転数：14rpm)で混練を行い、内容物温度が60℃に達した後、高速(自転回転数：35rpm、公転回転数：24rpm)に切替、混練を継続した。
【００７６】
樹脂S 2400g
Fast Yellow 7410 (Pigment Yellow 74)
(山陽色素株式会社製) 6000g
34質量%水酸化カリウム水溶液(KOH) 1118g
ジエチレングリコール 3000g
【００７７】
このとき、プラネタリーミキサー混練時の電流値は、初期7Aで、その後最大14Aまで達し、混練継続に伴い徐々に低下した。
続いて、撹拌槽内の混練物に、混練を継続しながらイオン交換水を20g／分で1000gのイオン交換水を加えた。その後、混練を継続しながら80g／分で8000gのイオン交換水を加えた。さらに、2000gのイオン交換水を加え、粘度調整物とし、取出した。
取り出した粘度調整物10.00kgに、ジエチレングリコール4779g、イオン交換水1051gを分散撹拌機で撹拌しながら少量づつ添加して、分散させた。さらに、ビーズミル(浅田鉄工製ナノミルNM-G2L)にて実施例1と同一条件で分散を実施し、顔料分散液A2を得た。
顔料分散液A2の固形分濃度は25.3%で、顔料濃度は17.3%であった。
【００７８】
（比較例２）
下記組成の混合物を、容量50LのプラネタリーミキサーPLM-V-50V(株式会社井上製作所製)に仕込み、ジャケットを加温し、内容物温度が60℃になるまで低速(自転回転数：21rpm、公転回転数：14rpm)で混練を行い、内容物温度が60℃に達した後、高速(自転回転数：35rpm、公転回転数：24rpm)に切替、混練を継続した。
【００７９】
樹脂S 2400g
Fast Yellow 7410 (Pigment Yellow 74)
（山陽色素株式会社製） 6000g
イオン交換水 1118g
ジエチレングリコール 3000g
【００８０】
プラネタリーミキサーの負荷電流値は高速開始時で6Aであった。高速での混練を30分間実施し、その後ジエチレングリコールを、50g／分で2000g加えた。その間の負荷電流値は、8Aを示し安定した。この状態で１時間混練を継続後、ジエチレングリコール／イオン交換水＝3000g／3500gの混合液を100g／分で加えた。混合液の添加終了後、30分間混練を継続し、粘度調整物を取出した。
この粘度調整物10kgに、ジエチレングリコール1903.1g、イオン交換水4200g、34質量%KOH水溶液510.6gを、分散撹拌機を用いて少量づつ添加し分散液化した。得られた分散液を実施例2と全く同様にしてビーズミルで分散を実施したが、分散機への送液圧力が上昇し、500ml/minでは送液できないため、50ml/minまで送液量を低下させ分散を実施し、顔料分散液B2を得た。
顔料分散液B2の固形分濃度は25.3質量%、顔料濃度は17.3質量%であった。
【００８１】
（実施例３）
下記組成の混合物を、容量50LのプラネタリーミキサーPLM-V-50V(株式会社井上製作所製)に仕込み、ジャケットを加温し、内容物温度が60℃になるまで低速(自転回転数：21rpm、公転回転数：14rpm)で混練を行い、内容物温度が60℃に達した後、高速(自転回転数：35rpm、公転回転数：24rpm)に切替、混練を継続した。
【００８２】
樹脂T 3000g
NOVOPERM YELLOW H2G (Pigment Yellow 120)
(クラリアントジャパン株式会社製) 5000g
34質量%水酸化カリウム水溶液(KOH) 1323.5g
ジエチレングリコール 3000g
【００８３】
このとき、プラネタリーミキサー混練時の電流値は、初期7Aで、その後最大12Aまで達し、混練継続に伴い徐々に低下した。
続いて、撹拌槽内の混練物に、混練を継続しながらイオン交換水を20g／分で1000gのイオン交換水を加えた。その後、混練を継続しながら80g／分で8000gのイオン交換水を加えた。さらに、2000gのイオン交換水を加え、粘度調整物とし、取出した。
取り出した粘度調整物10.00kgに、ジエチレングリコール3000g、イオン交換水1600gを分散撹拌機で撹拌しながら少量づつ添加して、分散させた。さらに、ビーズミル(浅田鉄工製ナノミルNM-G2L)にて実施例1と同一条件で分散を実施し、顔料分散液A3を得た。
顔料分散液A3の固形分濃度は24.9%で、顔料濃度は14.7%であった。
【００８４】
（比較例３）
実施例3の34質量%水酸化カリウム水溶液をイオン交換水とした下記組成の混合物を、容量50LのプラネタリーミキサーPLM-V-50V(株式会社井上製作所製)に仕込み、ジャケットを加温し、内容物温度が60℃になるまで低速(自転回転数：21rpm、公転回転数：14rpm)で混練を行い、内容物温度が60℃に達した後、高速(自転回転数：35rpm、公転回転数：24rpm)に切替、混練を継続した。
【００８５】
樹脂T 3000g
NOVOPERM YELLOW H2G (Pigment Yellow 120)
(クラリアントジャパン株式会社製) 5000g
イオン交換水 1323.5g
ジエチレングリコール 3000g
【００８６】
プラネタリーミキサーの負荷電流値は高速開始時で6Aであった。高速での混練を30分間実施し、その後ジエチレングリコールを、50g/分で2000g加えた。その間の負荷電流値は、8Aを示し安定した。この状態で１時間混練を継続後、ジエチレングリコール／イオン交換水＝3000g／3500gの混合液を100g／分で加えた。混合液の添加終了後、30分間混練を継続し、粘度調整物を取出した。
この粘度調整物10kgに、ジエチレングリコール960g、イオン交換水3833g、34質量%KOH水溶液635.6gを、分散撹拌機を用いて少量づつ添加し分散液化した。
得られた分散液を実施例3と全く同様にしてビーズミルで分散を実施したが、分散機への送液圧力が上昇し、500ml/minでは送液できないため、50ml/minまで送液量を低下させ分散を実施し、顔料分散液B3を得た。
顔料分散液B3の固形分濃度は26.5質量%で、顔料濃度は15.7質量%であった。
【００８７】
（実施例４）
下記組成の混合物を、容量50LのプラネタリーミキサーPLM-V-50V(株式会社井上製作所製)に仕込み、ジャケットを加温し、内容物温度が60℃になるまで低速(自転回転数：21rpm、公転回転数：14rpm)で混練を行い、内容物温度が60℃に達した後、高速(自転回転数：35rpm、公転回転数：24rpm)に切替、混練を継続した。
【００８８】
樹脂S 1500g
Fast Yellow 7413 (Pigment Yellow 74)
(山陽色素株式会社製) 5000g
34質量%水酸化カリウム水溶液(KOH) 670g
ジエチレングリコール 2400g
【００８９】
このとき、プラネタリーミキサー混練時の電流値は、初期7Aで、その後最大14Aまで達し、混練継続に伴い徐々に低下した。この状態で3時間混練を続けた。続いて、撹拌槽内の混練物に、混練を継続しながらイオン交換水を20g／分で1000gのイオン交換水を加えた。その後、混練を継続しながら80g／分で7000gのイオン交換水を加えた。さらに、2000gのイオン交換水を加え、粘度調整物とし、取出した。
取り出した粘度調整物10.00kgに、ジエチレングリコール1300g、イオン交換水2140gを分散撹拌機で撹拌しながら少量づつ添加して、分散させた。さらに、ビーズミル(浅田鉄工製ナノミルNM-G2L)にて実施例1と同一条件で分散を実施し、顔料分散液A4を得た。
顔料分散液A4の固形分濃度は25.6%で、顔料濃度は19.0%であった。
【００９０】
（比較例４）
下記組成の混合物を、容量50LのプラネタリーミキサーPLM-V-50V(株式会社井上製作所製)に仕込み、ジャケットを加温し、内容物温度が60℃になるまで低速(自転回転数：21rpm、公転回転数：14rpm)で混練を行い、内容物温度が60℃に達した後、高速(自転回転数：35rpm、公転回転数：24rpm)に切替、混練を継続した。
【００９１】
樹脂S 1500g
Fast Yellow 7413 (Pigment Yellow 74)
(山陽色素株式会社製) 5000g
イオン交換水 670g
ジエチレングリコール 2400g
【００９２】
プラネタリーミキサーの負荷電流値は高速開始時で6Aであった。高速での混練を3時間実施し、混練を継続しながらイオン交換水を20g／分で1000gのイオン交換水を加えた。その後、混練を継続しながら80g／分で7000gのイオン交換水を加えた。さらに、2000gのイオン交換水を加え、粘度調整物とし、取出した。
この粘度調整物10kgに、分散撹拌機を用いて34質量%KOH水溶液342gを加えて10分間撹拌し、更にジエチレングリコール1300g、イオン交換水1798gを加えて3時間撹拌を続け分散液化した。撹拌槽には未溶解の混練物が認められた。
得られた分散液を実施例1と全く同様にしてビーズミルで分散を実施したが、分散機への送液圧力が上昇し、500ml/minでは送液できないため、50ml/minまで送液量を低下させ分散を実施し、顔料分散液B4を得た。
顔料分散液B4の固形分濃度は22.4質量%、顔料濃度は16.6質量%であった。
【００９３】
（実施例５）
下記組成の混合物を、容量50LのプラネタリーミキサーPLM-V-50V(株式会社井上製作所製)に仕込み、ジャケットを加温し、内容物温度が60℃になるまで低速(自転回転数：21rpm、公転回転数：14rpm)で混練を行い、内容物温度が60℃に達した後、高速(自転回転数：35rpm、公転回転数：24rpm)に切替、混練を継続した。
【００９４】
樹脂S 1500g
Ink Jet Yellow 4G VP2532 (Pigment Yellow 155)
(クラリアントジャパン株式会社製) 5000g
34質量%水酸化カリウム水溶液(KOH) 670g
ジエチレングリコール 1500g
【００９５】
このとき、プラネタリーミキサー混練時の電流値は、初期7Aで、その後最大13Aまで達し、混練継続に伴い徐々に低下した。この状態で3時間混練を続けた。続いて、撹拌槽内の混練物に、混練を継続しながらイオン交換水を20g／分で1000gのイオン交換水を加えた。その後、混練を継続しながら80g／分で5000gのイオン交換水を加えた。さらに、2000gのイオン交換水を加え、粘度調整物とし、取出した。
取り出した粘度調整物10.00kgに、ジエチレングリコール1756g、イオン交換水4005gを分散撹拌機で撹拌しながら少量づつ添加して、分散させた。さらに、ビーズミル(浅田鉄工製ナノミルNM-G2L)にて実施例1と同一条件で分散を実施し、顔料分散液A5を得た。
顔料分散液A5の固形分濃度は23.2%で、顔料濃度は17.2%であった。
【００９６】
（比較例５）
下記組成の混合物を、容量50LのプラネタリーミキサーPLM-V-50V(株式会社井上製作所製)に仕込み、ジャケットを加温し、内容物温度が60℃になるまで低速(自転回転数：21rpm、公転回転数：14rpm)で混練を行い、内容物温度が60℃に達した後、高速(自転回転数：35rpm、公転回転数：24rpm)に切替、混練を継続した。
【００９７】
樹脂S 1500g
Ink Jet Yellow 4G VP2532 (Pigment Yellow 155)
(クラリアントジャパン株式会社製) 5000g
イオン交換水 670g
ジエチレングリコール 1500g
【００９８】
プラネタリーミキサーの負荷電流値は高速開始時で6Aであった。高速での混練を3時間実施し、混練を継続しながらイオン交換水を20g／分で1000gのイオン交換水を加えた。その後、混練を継続しながら80g／分で5000gのイオン交換水を加えた。さらに、2000gのイオン交換水を加え、粘度調整物とし、取出した。
この粘度調整物10kgに、分散撹拌機を用いて34質量%KOH水溶液342gを加えて10分間撹拌し、更にジエチレングリコール1756g、イオン交換水3663gを加えて3時間撹拌を続け分散液化した。撹拌槽には未溶解の混練物が認められた。
得られた分散液を実施例1と全く同様にしてビーズミルで分散を実施したが、分散機への送液圧力が上昇し、500ml/minでは送液できないため、50ml/minまで送液量を低下させ分散を実施し、顔料分散液B5を得た。
顔料分散液B5の固形分濃度は21.8質量%、顔料濃度は16.2質量%であった。
【００９９】
【表２】

【０１００】
（水性顔料分散液の評価）
上述の様にして得られた実施例、比較例の顔料分散液について、それぞれ顔料濃度が14.5質量%になるように、イオン交換水を加えて濃度調整を行った。
顔料濃度を調整した顔料分散液について、マイクロトラックUPA粒度分析計(Leeds & Northrup社製)で粒径測定を実施した。その際、粒径測定サンプルは粒径測定可能な濃度となるように、イオン交換水で適宜希釈した。
また、調整した顔料分散液をスライドグラス上に極少量採取し、スライドグラス上の分散液滴に空気を巻き込まないようにカバーグラスを乗せ、分散液膜厚を一定にした状態で、200倍の倍率で透過光による顕微鏡観察を行い、粗大粒子の観察を行った。
結果を表3に示した。
【０１０１】
【表３】

【０１０２】
分散液の粒径、顕微鏡観察結果より、本発明に係る実施例においては、従来の方法である、顔料と樹脂とを、塩基性化合物を添加しないで混練した後ビーズミルで分散する比較例の方法と比較して、塩基性化合物を添加して混練することにより、顕著に粒径も細かくすることができ、粗大粒子についてはその残存量を飛躍的に少なくすることができることが判った。
【０１０３】
（分散安定性（保存安定性）の評価）
実施例、比較例の顔料分散液について、分散液の評価と同様に、それぞれ顔料濃度が14.5%になるようにイオン交換水を加えて調整を行った。
顔料濃度の調整を行った分散液について、スクリュー管等のガラス容器に密栓し、60℃の恒温器で1週間の加熱試験を行い、加熱試験前後の粒径変化及び沈降物の有無等の分散液状態を目視で観察することにより、分散安定性の評価を実施した。 結果を表4に示した。
【０１０４】
【表４】

【０１０５】
分散液を一定温度で保存し、平均粒径変化及び沈降物の有無を観察した結果より、本発明に係る実施例においては、従来の方法である、顔料と樹脂とを、塩基性化合物を添加しないで混練した後ビーズミルで分散する比較例の方法と比較して、平均粒径の増加が少ないことは明白であり、また沈降物の発生が認められないことから、本発明の係る実施例ではより分散安定性が良好であることが判った。
【０１０６】
（インク組成物の調整）
得られた分散液A1、A2、A3、A4、A5、B1、B2、B3、B4及びB5を下記配合(表5)にて調整し、顔料濃度4.0質量%のインク組成物AI1、AI2、AI3、AI4、AI5、BI1、BI2、BI3、BI4及びBI5を得た。
【０１０７】
【表５】

＊：三洋化成製 (単位：部)
【０１０８】
（印字試験）
得られたインク組成物を、ENCAD社製NOVAJET PROに搭載し、印字試験を実施した。
具体的には、A4の印字用紙(ユポインクジェット専用紙)4枚に、ベタ印字と細線印字を行い、インクの吐出状態を確認した。
結果を表6に示した。
【０１０９】
【表６】

【０１１０】
◎：全ての印字サンプルで均一なベタ印字、細線部でも吐出不良、印字位置ズレ無し。
○：全ての印字サンプルで均一なベタ印字、細線部では吐出不良は無いが、印字位置ズレがわずかに見られる。
△：ベタ印字で吐出不良による濃度ムラが見られ、細線部でも吐出不良による印字抜けが部分的に見られる。
×：吐出不良による濃度ムラが顕著で、画像がかすれる。細線部でも吐出不良による印字抜けが顕著。
【０１１１】
この表6の結果より、本発明の実施例は比較例と比べると、インクの吐出状況では大きな差が発生しており、本発明実施例が格段に優れた吐出安定性があることが判る。
【０１１２】
【発明の効果】
イエロー顔料が安定に分散し(分散安定性が良好で)、それが長期保存においても維持される、長期保存安定性が良好な水性イエロー顔料分散液とインク組成物を得ることができた。
また、分散時間などの製造に要する時間が短く、製造効率が高い水性イエロー顔料分散液とインク組成物の製造方法、又収率の高い水性イエロー顔料分散液とインク組成物の製造方法を提供することができ、特に吐出特性に優れたインクジェット記録用のインク組成物を得ることができた。
【図面の簡単な説明】
【図１】 プラネタリーミキサーの構成の一例を示した斜視図。
【図２】 プラネタリーミキサーの一部拡大図。
【図３】 プラネタリーミキサーにおける撹拌羽根の軌跡を示した説明図。
【符号の説明】
１・・・・・・撹拌槽
２・・・・・・撹拌槽の上部
３・・・・・・撹拌槽の下部
４及び５・・・撹拌羽根
６・・・・・・ローター[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a kneaded product for an aqueous yellow pigment dispersion and a method for producing an aqueous yellow pigment dispersion and an ink composition using the same, and is particularly suitable for inkjet recording.
[0002]
[Prior art]
Conventionally, an aqueous pigment dispersion in which a pigment is dispersed in a liquid medium containing water as a main component has been proposed, and an ink composition is produced by diluting the aqueous pigment dispersion.
In producing an aqueous pigment dispersion, it is common to mix a pigment, water, an organic solvent, a resin, and an alkaline agent, and perform a pigment dispersion treatment using a disperser. As a result, an aqueous pigment dispersion is obtained in which a plurality of resin-coated particles in which a particulate pigment is coated with a resin are dispersed in a water-soluble solvent.
[0003]
On the other hand, when an ink composition for ink-jet recording is produced using an aqueous pigment dispersion, a product having significantly improved light resistance, water resistance and the like can be obtained as compared with those using a conventional dye.
Ink compositions for ink jet recording are strictly required for stability (ejection stability) when ejected from ink jet, long-term storage stability, and the like as compared with other applications. That is, it is necessary that fine pigment particles having as uniform a particle diameter as possible be stably dispersed in a liquid medium for a long period of time while being coated with a resin. In order to satisfy these requirements, it is necessary to have good dispersion stability and dispersion stability that can be stored for a long period of time at the stage of the aqueous pigment dispersion.
[0004]
Thus, recently, various studies have been conducted on aqueous pigment dispersions with regard to compositions suitable for inkjet recording, pigment dispersion methods, and the like.
For example, an aqueous solution in which a water-soluble resin and an alkali component are dissolved in water is prepared, the pigment is added to the solution, and the mixture is sufficiently stirred, and then dispersed using a high-speed sand mill having a high dispersion efficiency to obtain an aqueous pigment dispersion. A method has been proposed.
For example, after a yellow pigment and a polymer dispersant are obtained by a 2-roll milling apparatus, a dispersion method is obtained by dispersing the yellow pigment and a polymer dispersant in an aqueous carrier medium. An aqueous pigment dispersion is obtained by mixing the dispersion, potassium hydroxide as a neutralizing agent, and water. (For example, refer to Patent Document 1).
[0005]
[Patent Document 1]
Japanese Patent Laid-Open No. 6-157554 (Example 3)
[0006]
[Problems to be solved by the invention]
However, in the above production method, pre-kneading with a 2-roll milling device allows the pigment to be finer than the non-kneaded one and the dispersibility in the aqueous carrier medium can be improved. There has been a problem that pigment aggregates generated when the body is dispersed in an aqueous carrier medium cannot be completely prevented.
Further, this method has a problem that the dispersion time is long and the production efficiency is low. Also, the aqueous pigment dispersion thus obtained still has insufficient dispersion stability.
[0007]
The step of producing an aqueous pigment dispersion using a sand mill is usually performed using a low-viscosity dispersion liquid having a small solid content ratio such as a pigment. Therefore, it is difficult to apply a strong share to the pigment, and it takes a lot of time to grind the coarse particles of the pigment.
In addition, the aqueous pigment dispersion thus obtained contains a considerable amount of coarse particles having a particle diameter of 1 μm or more even after dispersion. In addition, since the ejection stability of the ink jet cannot be ensured as it is, a process for removing the coarse particles by centrifugation, filtration or the like is further required, and there is a problem that the production efficiency further decreases and the yield decreases.
[0008]
The present invention has been made in view of the above circumstances, and the yellow pigment is stably dispersed (dispersion stability is good), and it is maintained even during long-term storage. It is an object of the present invention to provide a technique capable of obtaining a liquid and an ink composition.
It is another object of the present invention to provide a method for producing an aqueous yellow pigment dispersion and an ink composition having a short production time such as dispersion time and high production efficiency.
Another object of the present invention is to provide an aqueous yellow pigment dispersion having a high yield and a method for producing an ink composition.
In particular, it is an object to provide a technique capable of obtaining an ink composition for ink jet recording excellent in ejection characteristics.
[0009]
[Means for Solving the Problems]
In order to solve the above problems and to produce an aqueous yellow pigment dispersion having good dispersion stability, the present inventors further blended a basic compound with a mixture containing a resin and a yellow pigment, and kneaded the mixture with high viscosity. After preparing a kneaded product, it was found that a method for producing an aqueous yellow pigment dispersion or an ink composition using the same by using the kneaded product was found to be suitable.
That is, in order to solve the above problems, the present inventors kneaded a mixture containing a resin having an anionic group, a yellow pigment, and a basic compound, and kneaded for a solid or semi-solid aqueous yellow pigment dispersion. A method for producing a kneaded product for an aqueous yellow pigment dispersion is provided.
[0010]
Further, the inventors of the present invention have prepared a process for producing a kneaded product for an aqueous yellow pigment dispersion by the above-described method for producing a kneaded product for an aqueous yellow pigment dispersion, and dispersing the kneaded product in a solution containing water as a main component. And a process for producing an aqueous yellow pigment dispersion. The method for producing an aqueous yellow pigment dispersion is provided.
In the present specification, in the production process of the kneaded product for the aqueous yellow pigment dispersion, the product before kneading is used as the mixture, and the product during or after kneading is used as the kneaded product.
Furthermore, the present inventors provide a method for producing an ink composition, comprising the steps of producing the aqueous yellow pigment dispersion and a step of diluting the aqueous yellow pigment dispersion with a water-soluble solvent to obtain an ink composition. To do.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The anionic group of the resin is neutralized by kneading the resin having an anionic group and the yellow pigment in the presence of the basic compound. Therefore, compared with the case where no basic compound is present, the dispersibility and solubility of the resin are improved, and the resin is partially dissolved or swollen and kneaded with the yellow pigment. Resin adsorption proceeds, and the kneaded product becomes a highly viscous clay kneaded product due to the presence of the basic compound.
Furthermore, the inventors of the present invention provide a method for producing a kneaded product for an aqueous yellow pigment dispersion, wherein the kneading is performed so that the mass of the mixture does not substantially change during kneading. I found it preferable to improve
[0012]
When the kneading step is performed using an open kneader such as a two roll or three roll, water in the kneaded product or a water-soluble organic solvent evaporates due to a temperature rise during kneading, The increase in the solid content ratio of the kneaded product is remarkable. Therefore, the effect of adding a basic compound at the initial stage of kneading to neutralize the anionic group of the resin and improve its dispersibility or solubility is diminished.
Furthermore, when kneading by an open system such as such a roll kneader, the yellow pigment certainly receives a share between rolls and is finely pulverized, but the solid content ratio at the end of kneading is as described above. Since it rises remarkably, the surface of the kneaded material is in a dry state. For this reason, when preparing an aqueous yellow pigment dispersion in the subsequent dispersion step, water or a water-soluble organic solvent should be further added to the kneaded product to pulverize and dissolve solid chips and disperse the yellow pigment. I must. Therefore, a burden is imposed on the dispersion process following the roll meat grinding, and the dispersion time may be prolonged, and even if dispersion is performed for a long time, coarse particles may remain.
In contrast, when the kneading is performed so that the mass of the mixture does not substantially change, the kneaded product for the aqueous yellow pigment dispersion liquid is produced without causing problems such as an increase in the viscosity of the kneaded product and an increase in the solid content ratio. Obtainable.
[0013]
Furthermore, in the method for producing a kneaded product for an aqueous yellow pigment dispersion, it is preferable to knead using a kneader having a stirring tank and stirring blades. In such a kneader, unlike the roll kneader as described above, it is possible to seal the stirring tank, prevent evaporation of water or water-soluble organic solvent during kneading, and the mass of the mixture during kneading Can be substantially unchanged.
For this reason, the solid content ratio of the kneaded product does not increase excessively, and can be easily mixed and dispersed in a diluting water-soluble solvent added to move to the dispersion step, thereby efficiently producing a dispersion. .
Further, the kneader is preferably a planetary mixer. The planetary mixer has a structure to stir and knead the kneaded material in the stirring tank using biaxial stirring blades that rotate and revolve with each other, and the dead space where the stirring blades do not reach in the stirring tank Less is. Moreover, although the shape of a blade | wing is thick and can apply high load, on the other hand, it can also be used like the normal stirrer which rotates a stirring blade in a stirring tank. For this reason, there is a wide range of materials to be kneaded from the high load region to the low load region, and one or both of water and a water-soluble organic solvent are added to the kneaded material after the kneading and diluted, stirred. All the dispersing operations can be performed in the same mixer without removing the kneaded material from the planetary mixer.
[0014]
When the aqueous yellow pigment dispersion kneaded product is dispersed in a water-soluble solvent to prepare an aqueous yellow pigment dispersion, it is preferably dispersed with a disperser using media. By using such a disperser, it is possible to simultaneously reduce the particle size by grinding the yellow pigment and adsorb the resin on the surface of the yellow pigment.
[0015]
In the aqueous yellow pigment dispersion, the dispersion state of the yellow pigment includes the particle size of the yellow pigment, the particle size of the resin-coated particles in which the yellow pigment is coated with the resin, the ratio of the yellow pigment to the resin, the resin and the water-soluble solvent. It is influenced by the composition. The fine resin-coated particles in which the surface of the fine yellow pigment particles are thinly and uniformly coated with the resin are stably dispersed in the water-soluble solvent, and the dispersed state is maintained even after long-term storage. However, it is preferable to obtain effects such as ejection stability in the ink composition for inkjet recording.
In the present invention, the water-soluble solvent or the aqueous medium means water or a solvent containing a water-soluble organic solvent that easily mixes with water.
Hereinafter, the method for producing a kneaded product for an aqueous yellow pigment dispersion, the method for producing an aqueous yellow pigment dispersion, and the method for producing an ink composition will be described in detail with examples in order.
[0016]
(1) Manufacturing method of kneaded material for aqueous yellow pigment dispersion
In the production of the kneaded product for the aqueous yellow pigment dispersion, at least
(1) a resin having an anionic group,
(2) Yellow pigment,
(3) Basic compound,
And knead | mixing the prepared mixture containing a solid or semi-solid aqueous yellow pigment dispersion liquid.
In the present invention, semi-solid means a highly viscous substance at room temperature.
Further, the solid content ratio of (1) resin and (2) yellow pigment is preferably 50 to 80% by mass in the obtained kneaded product for aqueous yellow pigment dispersion. When the solid content ratio is less than 50% by mass, the viscosity of the mixture is lowered, so that kneading is not sufficiently performed, and a share for pulverizing the yellow pigment is not sufficiently generated, which is not preferable. And by increasing the solid content ratio in this way, the viscosity of the kneaded product during kneading is kept moderately high, the share of the kneaded product from the kneading machine during kneading is increased, and the yellow pigment in the kneaded product is pulverized. The coating of the yellow pigment with the resin can proceed simultaneously. If the solid content ratio exceeds 80% by mass, kneading becomes difficult even if the resin is sufficiently softened by heating. In addition, it may be difficult to dissolve and disperse in a water-soluble solvent during the production of an aqueous yellow pigment dispersion, or it may be difficult to reduce the viscosity with a water-soluble solvent.
[0017]
Hereinafter, each configuration will be described in detail.
(1) Resin having an anionic group
The resin having an anionic group is obtained by polymerizing a monomer containing a monomer component having at least one kind of anionic group, and the monomer containing an anionic group functions as a hydrophilic group. In addition, it is preferable that the other monomer used for superposition | polymerization contains the hydrophobic monomer which has a hydrophobic group. As the resin having an anionic group, it is preferable to use a resin in which a monomer component having a hydrophilic group composed of an anionic group and a monomer component having a hydrophobic group coexist.
[0018]
Such resins include styrene resins, acrylic resins, maleic resins, polyvinyl acetate resins, polyvinyl sulfonate resins, polyester resins, polyurethane resins, polyamide resins, polyvinyl alcohol resins. Examples thereof include resins, polypyrrolidone resins, and cellulose resins.
As a hydrophobic monomer having a hydrophobic group used in the resin,
(Meth) acrylic acid alkyl esters such as methyl (meth) acrylate and ethyl (meth) acrylate;
(Meth) acrylic acid allyl esters such as phenyl (meth) acrylate, benzyl (meth) acrylate, phenylethyl (meth) acrylate;
Sulfonic acid group-containing (meth) acrylic acid esters such as sulfoethyl (meth) acrylate and sulfopropyl (meth) acrylate;
Hydroxyl-containing (meth) acrylic acid esters such as hydroxyethyl (meth) acrylate and hydroxypropyl (meth) acrylate;
Examples thereof include styrene-based monomers such as styrene, α-methylstyrene, and vinyl toluene; acrylonitrile, acrylamide, vinyl acetate, vinyl chloride, vinyl pyrrolidone, vinyl alcohol, and ethylene.
Of these, styrene monomers, and more preferably styrene monomers are preferred.
These can be used alone or in combination of two or more.
In addition, (meth) acrylate shows an acrylate and / or methacrylate, (meth) acrylic acid shows acrylic acid and / or methacrylic acid.
Examples of the monomer having an anionic group include carboxylic acid, sulfonic acid, and phosphoric acid. In particular, from the viewpoint of dispersion stability and long-term storage stability, a monomer containing a carboxyl group is preferable, and examples thereof include (meth) acrylic acid and maleic anhydride.
In the present invention, in view of dispersion stability and long-term storage stability, it is particularly preferable to use a (meth) acrylic acid-based monomer having a structure derived from (meth) acrylic acid.
[0019]
Further, from the viewpoints of dispersion stability and long-term storage stability, the resin having an anionic group is preferably a copolymer resin comprising a styrene monomer component which is a hydrophobic monomer component and a monomer component having an anionic group.
At this time, the monomer having an anionic group is preferably a hydrophilic monomer.
[0020]
In the copolymer resin comprising a styrene monomer component and a monomer component having an anionic group, the styrene monomer component is 50% by mass or more, preferably 70% by mass or more, preferably from the viewpoint of dispersion stability and long-term storage stability. It is preferably contained in an amount of 95% by mass or less.
By setting the content of the styrene monomer component in the copolymer resin to 50% by mass or more, the hydrophobicity of the copolymer resin increases, and in the aqueous system, the resin coating to the yellow pigment is performed more firmly. As a result, when the ink composition prepared through the aqueous yellow pigment dispersion is used for inkjet, even if the resin-coated particles are heated, the particle size is stable and the particle size stability is improved. In addition, the ejection stability is improved and a high print density is obtained. Further, it is effective for improving the durability of the coating film on the recording medium. If it exceeds 95% by mass, the content of the monomer component having an anionic group that contributes to dispersion is lowered, and there is a possibility that dispersion stability in water and long-term storage stability are lowered.
In the present invention, the term “monomer” refers to a monomer before polymerization, and the term “monomer component” refers to a structure derived from a monomer contained in a resin.
[0021]
From the viewpoint of long-term storage stability, the acid value of the resin is in the range of 60 to 300 mgKOH / g, preferably 100 to 180 mgKOH / g, more preferably 120 to 170 mgKOH / g. The acid value is the number of milligrams (mg) of potassium hydroxide (KOH) necessary to neutralize 1 g of resin, and is an amount expressed in mgKOH / g.
If the acid value is less than 60, the hydrophilicity becomes small and the dispersion stability of the yellow pigment may be lowered. On the other hand, if the acid value is greater than 300, the yellow pigment is likely to aggregate, and the water resistance of the printed product using the ink composition may be reduced.
[0022]
In addition, the mass average molecular weight of the resin having an anionic group is 3000 to 50000, more preferably 4000 to 40000, and still more preferably 5000 to 30000. The reason why it is 3000 or more is that the lower the molecular weight, the better the initial dispersibility, but the long-term storage stability tends to decrease. If it exceeds 50,000, not only will the viscosity of the aqueous yellow pigment dispersion increase, but also the dispersibility and solubility of the resin will tend to decrease.
By using a resin having a weight average molecular weight in the above preferred range, both the stability of the yellow pigment in the water-soluble solvent and the durability of the coating film formed on the recording medium can be achieved.
[0023]
The glass transition point of the resin is 90 ° C. or higher, preferably 100 ° C. or higher, substantially 150 ° C. or lower.
When the glass transition point is 90 ° C. or higher, the durability of the image formed by the ink composition is improved, and the thermal stability of the ink composition is improved. For this reason, even if the water-based ink composition for ink-jet recording prepared from the water-based pigment dispersion is used for thermal jet type ink-jet recording, it does not cause a characteristic change that causes ejection failure by heating, which is preferable. The glass transition point of the resin can be adjusted by changing the molecular weight.
[0024]
▲ 2 ▼ Yellow pigment
The yellow pigment in the present invention has a color index No. In the above, organic pigments are shown from among those classified as pigment yellow.
Specific examples include the following pigments.
Anthrapyrimidine pigments; CI pigment yellow 108, etc.
Flavanthrone pigments; CI pigment yellow 24 etc.
Anthraquinone pigments; CI pigment yellow 196, etc.
Perinone pigments; CI pigment yellow 196, etc.
Quinophthalone pigments; CI pigment yellow 138, etc.
Isoindoline pigments: CI pigment yellow 139, CI pigment yellow 185, etc.
Isoindolinone pigments: CI pigment yellow 109, CI pigment yellow 110, CI pigment yellow 173, CI pigment yellow 185, etc.
Azomethine pigments; CI pigment yellow 101, CI pigment yellow 129, etc.
Insoluble azo pigments include CI Pigment Yellow 120, CI Pigment Yellow 151, CI Pigment Yellow 154, CI Pigment Yellow 175, CI Pigment Yellow 180, CI Pigment Yellow 181, CI Pigment Yellow 1, CI Pigment Yellow 65, CI Pigment Yellow 73 CI Pigment Yellow 74, CI Pigment Yellow 116, CI Pigment Yellow 12, CI Pigment Yellow 13, CI Pigment Yellow 17, CI Pigment Yellow 81, CI Pigment Yellow 83, CI Pigment Yellow 155, CI Pigment Yellow 214, CI Pigment Yellow 128 Monoazo and disazo pigments.
[0025]
The pigment may be a dry pigment in the form of powder, granule or block, or a wet cake or slurry.
Particularly preferred are insoluble azo pigments from the viewpoint of color tone. Among these, pigments selected from CI Pigment Yellow 74, CI Pigment Yellow 120, CI Pigment Yellow 128, CI Pigment Yellow 155, and CI Pigment Yellow 180 are more preferable.
[0026]
The yellow pigment is preferably blended in an amount of 15 to 75% by mass in the mixture. In general, in order to obtain an ink composition having a constant pigment concentration by diluting the aqueous yellow pigment dispersion, it is possible to produce more ink compositions by increasing the concentration in the aqueous yellow pigment dispersion as much as possible. This is advantageous in terms of production efficiency. However, increasing the yellow pigment concentration deteriorates the storage stability of the aqueous yellow pigment dispersion. Therefore, the stability of the dispersion of the yellow pigment and the stability of the kneaded product for the aqueous yellow pigment dispersion are substantially secured. Therefore, the content is 70% by mass or less, preferably 45 to 65% by mass.
[0027]
Other pigment derivatives can be used in combination to stabilize the dispersion of the yellow pigment, as commonly used in pigment dispersion. Examples of these derivatives include sulfonic acid compounds, carboxylic acid compounds, and phosphoric acid compounds of pigments to be used.
[0028]
Further, regarding the mass ratio between the yellow pigment and the resin (Resin), it is sufficient that the resin is present in an amount necessary for stably coating the surface of the yellow pigment, and it is not preferable to contain a resin exceeding the amount. When an excessive amount of resin is present, the amount of free resin that does not adsorb to the yellow pigment increases when an aqueous yellow pigment dispersion or ink composition is prepared. Therefore, when the resin is used as an ink composition for inkjet recording, Adhering to the ink nozzles tends to cause ink discharge failure, and particularly in a thermal jet printer, there is a high risk of occurrence of this discharge failure problem.
[0029]
Therefore, in the production of the aqueous yellow pigment dispersion kneaded product of the present invention, the mass ratio of the resin / yellow pigment in the aqueous yellow pigment dispersion kneaded product is preferably 1/10 to 2/1. More preferably, it is / 10 to 6/10.
[0030]
The kneaded product for an aqueous yellow pigment dispersion needs to contain an amount of resin that can uniformly coat the surface of the yellow pigment. For this reason, if the blending ratio of the yellow pigment is too large, the yellow pigment is not sufficiently covered with the resin, and the dispersion stability and long-term storage stability may be lowered. However, if an excessive amount of resin exceeding this required amount is contained, the resin existing in a particle state or dissolved state in water or a water-soluble organic solvent increases without adhering to the surface of the yellow pigment. This causes an increase in viscosity and is not preferable.
[0031]
(3) Basic compounds
By mixing a resin having an anionic group and a basic compound, a kneaded product for an aqueous yellow pigment dispersion in which the anionic group is neutralized is obtained. As a result, the affinity between the aqueous yellow pigment dispersion kneaded product and water is improved, and when the aqueous yellow pigment dispersion is produced, the aqueous yellow pigment dispersion kneaded material is quickly dispersed in water, improving the production efficiency. To do. Further, the dispersion state of the resin-coated yellow pigment in the aqueous yellow pigment dispersion becomes more stable, and the dispersion stability and long-term storage stability are also improved.
[0032]
In addition, when a basic compound is blended, the yellow pigment can be kneaded in a state in which the resin is easily covered by the interaction between the basic compound and the resin having an anionic group. Therefore, the yellow pigment is finely pulverized during the kneading, and the coarse particles are likely to be reduced. The step of removing the coarse particles in a subsequent step can be omitted, and the yield can be improved.
[0033]
As the basic compound, any of an inorganic basic compound and an organic basic compound can be used. In terms of easy adjustment of alkali strength, inorganic basic compounds are more preferable.
[0034]
Examples of the organic basic compound include amines. For example, common amines such as methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine and triethylamine can be exemplified. In the case of amine, since it is generally liquid, it can be used as it is.
[0035]
Examples of inorganic basic compounds include hydroxides of alkali metals such as potassium and sodium, ammonium hydroxide; carbonates of alkali metals such as potassium and sodium; carbonates of alkaline earth metals such as calcium and barium; It can be illustrated.
[0036]
Among them, a strong alkali is preferable because it is effective for enhancing the dispersibility of the resin by neutralizing the resin containing an anionic group. Specifically, an alkali metal such as potassium hydroxide or sodium hydroxide is preferable. Hydroxides are preferred.
The basic compound is suitably added as an aqueous solution in order to efficiently obtain the above effects. For this reason, a water-soluble basic compound is used suitably.
The inorganic basic compound is usually used in the form of an aqueous solution having a concentration of about 20 to 50% by mass from the viewpoint of improving the mixing property.
[0037]
The basic compound is preferably used in such an amount that the neutralization rate of the resin having an anionic group is 20% or more, and substantially has dispersion stability during long-term storage. In order not to gel, it is preferably 200% or less, particularly preferably 80% to 120%. By setting to a preferable range, the improvement of the dispersion speed, dispersion stability, and long-term storage stability in the water-soluble solvent are further improved.
[0038]
Furthermore, before kneading, the basic compound is preferably mixed together with other blending components to be blended into the mixture to prepare a mixture.
For example, the mixture is divided into a plurality of stages by preparing a resin aqueous solution by mixing a resin containing an anionic group, water and a basic compound in advance and adding this to other compounding ingredients such as a yellow pigment. However, it is more efficient to adsorb the resin to the surface of the yellow pigment by mixing the basic compound and other ingredients together to prepare a mixture for kneading. Is preferable.
[0039]
Here, the neutralization rate is a value calculated by the following formula.
Neutralization rate (%) = ((mass of basic compound (g) × 56 × 1000) / (resin acid value × basic compound equivalent × resin amount (g))) × 100
A neutralization rate (%) of 100% or more means that an excess base that is theoretically necessary to neutralize the acid value of the resin is used.
[0040]
(4) Water-soluble organic solvent
In producing a kneaded product for an aqueous yellow pigment dispersion, it is preferable to knead in the presence of a certain amount of solvent. If the solvent is not present, sufficient kneading cannot be performed, and the surface of the yellow pigment does not get wet, so that the resin coating may be insufficient.
[0041]
Therefore, when a water-soluble organic solvent is blended in the kneaded product for the aqueous yellow pigment dispersion, the resin is dissolved, partially dissolved, or swollen with the water-soluble organic solvent, so that the resin is uniformly formed on the surface of the yellow pigment particles. Can be formed. As a result, the dispersion stability can be further improved in the aqueous yellow pigment dispersion and the ink composition.
In addition, when an aqueous solution of a basic compound is used, or when the basic compound is in a liquid state like an amine, these serve as the above-mentioned solvent, so there is no need to add a water-soluble organic solvent. is there.
[0042]
Examples of the water-soluble organic solvent include glycols such as ethylene glycol, diethylene glycol, triethylene glycol tetraethylene glycol, propylene glycol, polyethylene glycol, and polypropylene glycol;
Diols such as butanediol, pentanediol, hexanediol, and diols of the same family;
Glycol esters such as propylene glycol laurate;
Diethylene glycol ethers such as ethylene glycol monobutyl ether and carbitol;
Monoglycol ethers such as cellosolve including diethylene glycol monoethyl, diethylene glycol monobutyl, diethylene glycol monohexyl, propylene glycol ether, dipropylene glycol ether, and triethylene glycol ether;
Alcohols such as methanol, ethanol, isopropyl alcohol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, butyl alcohol, pentyl alcohol, and alcohols of the same family;
Or various other solvents known as water-soluble organic solvents such as sulfolane, esters, ketones, lactones such as γ-butyrolactone, lactams such as N- (2-hydroxyethyl) pyrrolidone, glycerin and its derivatives, etc. Can be mentioned.
These water-soluble organic solvents can be used alone or in combination.
[0043]
The selection of the water-soluble organic solvent is determined depending on the resin to be used, but a solvent having a certain degree of solubility is preferable, and the addition amount is adjusted depending on the solubility of the resin.
[0044]
The water-soluble organic solvent also serves as an anti-drying agent in the aqueous yellow pigment dispersion and the ink composition. Therefore, polyhydric alcohols having a high boiling point, a low volatility, and a high surface tension are preferable. Glycols such as ethylene glycol are preferred. In general, glycols are often contained in ink compositions, and there is no problem even if they remain in the final product.
[0045]
The water-soluble organic solvent varies depending on the resin to be used, but is usually 10 to 50% by mass, preferably 20 to 40% by mass in the charged mixture. The addition amount is about 1/2 to 5 times the resin amount, and preferably about 1 to 4 times the resin amount. If the amount of the water-soluble organic solvent is less than 1/2 of the resin amount, the resin cannot be dissolved, partially dissolved, or swollen, and the dispersion stability of the yellow pigment may be lowered. On the other hand, if it exceeds 5 times, the viscosity of the mixture for kneading is lowered and sufficient kneading cannot be performed, so that the dispersibility of the yellow pigment is lowered, and the ink composition may cause image quality deterioration such as ejection failure. In addition, as mentioned above, when what is derived from a basic compound etc. and plays the role of a solvent is mix | blended, it is preferable to determine the compounding quantity of a water-soluble organic solvent in consideration of this.
[0046]
Further, the water-soluble organic solvent is preferably blended in a mass ratio of 1/5 times or more, preferably 1/3 to 1 times that of the yellow pigment. As a result, the kneading process proceeds while the resin is always in a semi-dissolved or swollen state, and the yellow pigment surface is satisfactorily coated with the resin. If it is less than 1/5, the surface of the yellow pigment cannot be sufficiently wet at the initial stage of kneading, or the resin cannot be dissolved, partially dissolved, or swollen, and the effect may not be sufficiently obtained. is there.
[0047]
(5) Kneading method
In the present invention, the yellow pigment is not directly dispersed in the water-soluble solvent, but first, the yellow pigment is kneaded with the resin and then dispersed in the water-soluble solvent. Therefore, since the yellow pigment is finely pulverized during this kneading, coarse particles can be reduced.
At this time, since the basic compound is added as described above, the coarse particles are remarkably reduced by the interaction between the basic compound and the resin having an anionic group.
Therefore, the step of removing the coarse particles can be omitted, and the production efficiency can be improved and the yield can be improved.
[0048]
In the present invention, it is preferable to knead so that the mass of the mixture (kneaded material) does not substantially change so that water, water-soluble organic solvent, and the like do not evaporate during kneading. Therefore, there is always a certain amount of solvent in the mixture from the start to the end of kneading, and the solvent that wets the surface of the yellow pigment at the beginning of kneading is preferably dissolved, swollen or partially dissolved by the solvent. The replacement of the yellow pigment with the resin proceeds smoothly, and the yellow pigment is sufficiently coated. As a result, the dispersion stability and long-term storage stability of the aqueous yellow pigment dispersion and the ink composition are remarkably improved. Further, even after the completion of the kneading, almost the same amount of the solvent remains as at the start of the kneading, and the dissolution and dispersion of the mixture after the kneading can proceed in a very short time.
[0049]
For this purpose, a kneader for kneading in a closed system is preferred, and a kneader equipped with a stirring tank and a uniaxial or multiaxial stirring blade is preferably used. The number of stirring blades is not particularly limited, but two or more stirring blades are preferable in order to obtain a high kneading action.
When a kneader having such a configuration is used, a kneaded product for an aqueous yellow pigment dispersion is produced and then diluted and dispersed directly with a water-soluble solvent in the same stirring tank to produce an aqueous yellow pigment dispersion. be able to.
Note that substantially no change in mass means that the weight of the kneaded material during or after kneading is preferably maintained in the range of 90% by mass or more with respect to the amount of the mixture before kneading. And
[0050]
Examples of such an apparatus include a Henschel mixer, a pressure kneader, a Banbury mixer, a planetary mixer, and the like, and a planetary mixer is particularly preferable. In the present invention, kneading is preferably performed in a state where the yellow pigment concentration and the solid content concentration of the yellow pigment and the resin are high, so that the viscosity of the kneaded material varies in a wide range depending on the kneaded state of the kneaded material. This is because the planetary mixer can cope with a wide range from a low viscosity to a high viscosity.
[0051]
1 to 3 show an example of the configuration of a planetary mixer. In the figure, reference numeral 1 is a stirring tank, and this hollow cylindrical stirring tank 1 is substantially divided into two parts in the upper and lower sides, and inside the upper surface of the upper member 2 of the stirring tank 1, as shown in an enlarged view in FIG. Further, stirring blades 4 and 5 made of a frame blade are rotatably provided.
During stirring, the upper member 2 and the lower member 3 are integrated to form a closed system. Inside the upper member 2 of the agitation tank 1, as shown in an enlarged view in FIG. 2, agitation blades 4 and 5 made of frame-type blades are held by a single rotor 6. When the rotor 6 rotates (revolves), the stirring blades 4 and 5 rotate (rotate) in the same direction. Then, as shown in FIG. 3, the two agitating blades 4 and 5 rotate along with the revolution of the rotor, respectively, so that the kneading object loaded inside the agitation tank 1 while performing so-called planetary motion (planetary motion) Kneading is performed. FIG. 3 shows the locus of the tips of the two stirring blades 4 and 5 in one revolution of the stirring tank 1.
[0052]
In the planetary mixer, a powerful shearing force acts between the stirring blades 4 and 5 and between the stirring blades 4 and 5 and the inner surface of the stirring tank 1 by such planetary motion of the stirring blades 4 and 5. High stirring, kneading and dispersing action can be obtained.
[0053]
When kneading using a closed kneader such as a planetary mixer, the current consumption gradually increases with time, reaches a maximum value within 30 minutes, and then gradually decreases.
That is, when the mixture is heated while being heated to a predetermined temperature (depending on the type of resin, for example, 40 to 70 ° C.), the resin becomes viscous and mixed with the yellow pigment, A large load is applied to the rotation of the stirring blades 4 and 5. At this time, a large shearing force is applied to the material between the stirring blades 4 and 5 and between the stirring blades 4 and 5 and the stirring tank 1, and the yellow pigment is efficiently pulverized. Is sufficiently dispersed and mixed in the material and coated with resin. And especially when using a closed kneader like a planetary mixer, since effective kneading is performed, the resin, yellow pigment, water-soluble organic solvent are almost completely mixed within 30 minutes, the stirring blade 4, The load on 5 is reduced. As a result, current consumption gradually decreases.
[0054]
Thus, in the present invention, when mixing is performed using a closed system kneader such as a planetary mixer, one or more consumptions in the graph of the relationship between the kneading time and the power consumption of the kneading machine (planetary mixer). The characteristic that the maximum value of electric power is obtained is seen.
[0055]
When kneaded in such a closed system, the mass of the kneaded material does not substantially change during kneading with respect to the mass of the charged mixture, and a kneaded product for an aqueous yellow pigment dispersion having the same composition as the charged is obtained. Manufacturing stability is improved.
Further, since the kneading is performed in a state where the yellow pigment concentration and the solid content concentration are high from the beginning of the kneading, the yellow pigment is crushed by the shearing force applied by kneading, and undispersed coarse particles are reduced. As a result, it is not necessary to remove coarse particles in a later step, and the yield is improved.
In addition, when removing a water-soluble organic solvent, it can also be removed by heating and drying after kneading.
[0056]
(2) Method for producing aqueous yellow pigment dispersion
The kneaded product for an aqueous yellow pigment dispersion is usually a semisolid or solid kneaded product. Therefore, this aqueous yellow pigment dispersion is dispersed to produce an aqueous yellow pigment dispersion. Since the yellow pigment in the aqueous yellow pigment dispersion kneaded product has already been crushed at the time of producing the aqueous yellow pigment dispersion kneaded product, the dispersion time for obtaining the aqueous yellow pigment dispersion is short, and the production efficiency Will improve.
Further, the kneaded product for an aqueous yellow pigment dispersion of the present invention dissolves and disperses quickly because of its good solubility and dispersibility in water due to the interaction between the resin having an anionic group and the basic compound. Thus, it is a major characteristic of the kneaded product for aqueous yellow pigment dispersion liquid of the present invention that it is quickly dispersed and dissolved in water and stably maintained.
[0057]
In the present invention, the water-soluble solvent includes known water used for water-based inkjet inks or water-soluble organic solvents that are mutually soluble in water.
[0058]
As the disperser, a known one can be used. For example, in the case of using a medium, a baint shaker, a ball mill, an attritor, a basket mill, a sand mill, a sand grinder, a dyno mill, a disperse mat, an SC mill, a spike mill, Agitator mill, nanomill, picomill and the like can be mentioned.
As the medium, known fine particles such as glass, ceramics, metal, metal oxide, and plastic can be used.
Examples of those that do not use media include ultrasonic homogenizers, nanomizers, resolvers, dispersers, and high-speed impeller dispersers. Among these, dispersers that use media are preferable because of their high dispersibility. The concentration may be adjusted with a water-soluble solvent as necessary after dispersion.
Further, when preparing the aqueous yellow pigment dispersion, various known additives such as an alkali agent can be further blended as needed, and the addition of an alkali agent is preferable because the dispersion stability is improved.
[0059]
Depending on the type of disperser used, before performing dispersion (main dispersion) with a disperser, a water-soluble solvent is added to the kneaded product for an aqueous yellow pigment dispersion as necessary, mixed, diluted, It is preferable to adjust the viscosity to be suitable for processing with the disperser (hereinafter, the viscosity-adjusted product may be referred to as a viscosity-adjusted product).
For example, when a sand mill is used, it is preferable to perform dispersion by driving the sand mill after diluting to a solid content concentration of 10 to 40% by mass and adjusting the viscosity to 10 to several hundred mPa · s.
[0060]
In the present invention, for example, after kneading with a kneader equipped with the above-described stirring tank and stirring blade to obtain a kneaded product, by adding a water-soluble solvent to the kneaded product in this stirring tank, and mixing, Viscosity adjustment can be performed. Therefore, the production from the kneaded product to the viscosity adjustment can be continuously performed with one apparatus, and the production efficiency can be improved. For example, the viscosity-adjusted product is taken out from the stirring tank as necessary, and dispersed with the above-mentioned disperser to obtain an aqueous yellow pigment dispersion.
In addition, after adjusting to a predetermined viscosity in the stirring tank, it is further taken out from the stirring tank and mixed with a water-soluble solvent to adjust the viscosity to obtain a viscosity-adjusted product, which is further dispersed in the water-soluble solvent to form an aqueous solution. A yellow pigment dispersion can also be obtained.
[0061]
(3) Method for producing ink composition
The ink composition can be produced by further diluting the aqueous yellow pigment dispersion obtained as described above with a water-soluble solvent. The concentration of the yellow pigment contained in the ink composition is preferably about 2 to 10% by mass.
[0062]
It is preferable to add a water-soluble organic solvent to the water-soluble solvent for diluting the aqueous yellow pigment dispersion because it contributes to drying prevention, viscosity adjustment, and concentration adjustment in the ink composition. Examples of the water-soluble organic solvent are the same as those used for dispersing the kneaded product for an aqueous yellow pigment dispersion described above.
[0063]
In addition, it is preferable that a water-soluble organic solvent exhibiting permeability to the recording medium is blended to impart permeability to the ink composition. In the ink composition, the penetrability is a characteristic necessary for adjusting the penetrability of the ink composition (yellow pigment) into the recording medium and the dot diameter on the recording medium.
Examples of water-soluble organic solvents exhibiting permeability include lower alcohols such as ethanol and isopropyl alcohol; ethylene oxide adducts of alkyl alcohols such as ethylene glycol hexyl ether and diethylene glycol butyl ether; propylene oxide adducts of alkyl alcohols such as propylene glycol propyl ether Etc.
[0064]
In addition to the water-soluble solvent and the kneaded product for the aqueous yellow pigment dispersion, for example, a known additive can be blended in the ink composition.
As what can be mix | blended, an alkali agent, a pH adjuster, surfactant, antiseptic | preservative, a chelating agent, a plasticizer, antioxidant, a ultraviolet absorber, an ultraviolet curable resin etc. can be illustrated, for example.
In the present invention, for example, an ink composition can be produced by adding an aqueous yellow pigment dispersion, a water-soluble solvent, and various additives as necessary, and stirring uniformly.
[0065]
This ink composition can be suitably used as an ink for inkjet recording. The inkjet method to be applied is not particularly limited, but examples of known ones such as a continuous jet type (charge control type, spray type, etc.), on-demand type (piezo type, thermal type, electrostatic suction type, etc.) can do.
And when this ink composition is applied to these various ink jet systems, it becomes possible to discharge ink very stably.
[0066]
【Example】
Hereinafter, the present invention will be described in detail with reference to examples.
Unless otherwise specified, “part” means “part by mass” and “%” means “mass%”.
The yellow pigments used in the examples and comparative examples are as follows.
[0067]
[Table 1]

[0068]
Similarly, the resins S and T used in the examples and comparative examples are as follows. Resin S: Resin having a monomer composition ratio of styrene / methacrylic acid / acrylic acid = 77/13/10 (mass ratio), a mass average molecular weight of 12000, an acid value of 152 mgKOH / g, and a glass transition point of 107 ° C.
Resin T: Resin having a monomer composition ratio of styrene / methacrylic acid / acrylic acid = 77/13/10 (mass ratio), a molecular weight of 7500, an acid value of 150 mgKOH / g, and a glass transition point of 107 ° C.
[0069]
Example 1
A mixture of the following composition was charged into a planetary mixer PLM-V-50V (made by Inoue Seisakusho Co., Ltd.) with a capacity of 50 L, the jacket was heated, and the speed was low (rotation speed: 21 rpm) until the content temperature reached 60 ° C. Kneading was performed at a revolution speed of 14 rpm, and after the temperature of the contents reached 60 ° C., the speed was changed to a high speed (35 rpm, revolution speed: 24 rpm) and the kneading was continued.
[0070]
Resin S 2500g
IRGAPHOR Yellow 8GCF (Pigment Yellow 128)
(Ciba Specialty Chemicals Co., Ltd.) 5000g
34 mass% potassium hydroxide aqueous solution (KOH) 1118 g
Diethylene glycol 3000g
Ion exchange water 1000g
[0071]
The planetary mixer current when switching to high speed was 7A. Thereafter, the kneading was continued, and the maximum current value of the planetary mixer was 12 A. 30 minutes after showing the maximum current value, the planetary mixer current value dropped to 8 A, and kneading was continued for 3 hours in this stable state to obtain a kneaded product.
Subsequently, 1000 g of ion-exchanged water was added to the kneaded product in the stirring tank at 13 g / min while continuing kneading. Thereafter, 4800 g of ion-exchanged water was added at 50 g / min while continuing kneading. Furthermore, 1500 g of ion-exchanged water was added to obtain a viscosity-adjusted product, which was taken out.
[0072]
Diethylene glycol (3514.4 g) and ion-exchanged water (2184.8 g) were added to 10.00 kg of the taken out viscosity-adjusted product little by little while stirring with a dispersion stirrer, and dispersed. Further, dispersion was carried out with a bead mill (Nanomill NM-G2L manufactured by Asada Tekko Co., Ltd.) under the following conditions to obtain a pigment dispersion A1.
[0073]
Distributed condition
Disperser Nanomill NM-G2L (Asada Iron Works)
Beads φ0.3mm zirconia beads
Bead filling 85%
Cooling water temperature 10 ℃
Rotation speed 2660rpm (disk peripheral speed: 12.5m / sec)
Delivery rate 500g / min
Dispersion was performed by passing the disperser once (1 pass) under the above conditions.
The pigment dispersion A1 had a solid content concentration of 25.4% by mass and a pigment concentration of 16.1% by mass.
[0074]
(Comparative Example 1)
A viscosity-adjusted product was obtained using a planetary mixer in the same manner as in Example 1, except that ion-exchanged water was used instead of the 34 mass% potassium hydroxide aqueous solution in Example 1.
Unlike in Example 1, the state during kneading in this planetary mixer did not change clearly and changed from 7 to 8A.
To 10 kg of the obtained viscosity-adjusted product, 3514.4 g of diethylene glycol, 561.2 g of 34 mass% potassium hydroxide aqueous solution, and 1749.2 g of ion-exchanged water were added little by little while stirring with a dispersion stirrer, and dispersed. Furthermore, dispersion was carried out with a bead mill in exactly the same manner as in Example 1. However, since the liquid feeding pressure to the disperser increased and liquid feeding could not be performed at 500 ml / min, the liquid feeding amount was reduced to 30 ml / min to disperse. And pigment dispersion B1 was obtained.
The solid content concentration of the pigment dispersion B1 was 25.1% by mass, and the pigment concentration was 15.9% by mass.
[0075]
(Example 2)
A mixture of the following composition was charged into a planetary mixer PLM-V-50V (made by Inoue Seisakusho Co., Ltd.) with a capacity of 50 L, the jacket was heated, and the speed was low (rotation speed: 21 rpm) until the content temperature reached 60 ° C. Kneading was performed at a revolution speed of 14 rpm, and after the temperature of the contents reached 60 ° C., the speed was changed to a high speed (35 rpm, revolution speed: 24 rpm) and the kneading was continued.
[0076]
Resin S 2400g
Fast Yellow 7410 (Pigment Yellow 74)
(Sanyo Color Co., Ltd.) 6000g
34 mass% potassium hydroxide aqueous solution (KOH) 1118 g
Diethylene glycol 3000g
[0077]
At this time, the current value during the kneading of the planetary mixer was 7A at the initial stage, and then reached a maximum of 14A, and gradually decreased as the kneading continued.
Subsequently, 1000 g of ion-exchanged water was added to the kneaded product in the stirring tank at 20 g / min while continuing kneading. Thereafter, 8000 g of ion-exchanged water was added at 80 g / min while continuing kneading. Furthermore, 2000 g of ion-exchanged water was added to obtain a viscosity-adjusted product, which was taken out.
Diethylene glycol 4779 g and ion-exchanged water 1051 g were added to 10.00 kg of the taken out viscosity-adjusted product little by little while stirring with a dispersion stirrer, and dispersed. Further, the dispersion was carried out with a bead mill (Nanomill NM-G2L manufactured by Asada Tekko Co., Ltd.) under the same conditions as in Example 1 to obtain a pigment dispersion A2.
The pigment dispersion A2 had a solid content concentration of 25.3% and a pigment concentration of 17.3%.
[0078]
(Comparative Example 2)
A mixture of the following composition was charged into a planetary mixer PLM-V-50V (made by Inoue Seisakusho Co., Ltd.) with a capacity of 50 L, the jacket was heated, and the speed was low (rotation speed: 21 rpm) until the content temperature reached 60 ° C. Kneading was performed at a revolution speed of 14 rpm, and after the temperature of the contents reached 60 ° C., the speed was changed to a high speed (35 rpm, revolution speed: 24 rpm) and the kneading was continued.
[0079]
Resin S 2400g
Fast Yellow 7410 (Pigment Yellow 74)
(Sanyo Color Co., Ltd.) 6000g
Ion exchange water 1118g
Diethylene glycol 3000g
[0080]
The load current value of the planetary mixer was 6A at the start of high speed. Kneading at high speed was carried out for 30 minutes, and then 2000 g of diethylene glycol was added at 50 g / min. During that time, the load current value was 8 A and stabilized. After kneading for 1 hour in this state, a mixed solution of diethylene glycol / ion exchanged water = 3000 g / 3500 g was added at 100 g / min. After completion of the addition of the mixed solution, kneading was continued for 30 minutes, and the viscosity-adjusted product was taken out.
To 10 kg of this viscosity-adjusted product, 1903.1 g of diethylene glycol, 4200 g of ion exchange water, and 510.6 g of 34 mass% KOH aqueous solution were added little by little using a dispersion stirrer to form a dispersion. The obtained dispersion was dispersed in a bead mill in exactly the same manner as in Example 2. However, since the liquid feeding pressure to the disperser increased and the liquid could not be fed at 500 ml / min, the liquid feeding amount was reduced to 50 ml / min. The dispersion was carried out by lowering to obtain a pigment dispersion B2.
The solid content concentration of the pigment dispersion B2 was 25.3% by mass, and the pigment concentration was 17.3% by mass.
[0081]
(Example 3)
A mixture of the following composition was charged into a planetary mixer PLM-V-50V (made by Inoue Seisakusho Co., Ltd.) with a capacity of 50 L, the jacket was heated, and the speed was low (rotation speed: 21 rpm) until the content temperature reached 60 ° C. Kneading was performed at a revolution speed of 14 rpm, and after the temperature of the contents reached 60 ° C., the speed was changed to a high speed (35 rpm, revolution speed: 24 rpm) and the kneading was continued.
[0082]
Resin T 3000g
NOVOPERM YELLOW H2G (Pigment Yellow 120)
(Clariant Japan Co., Ltd.) 5000g
34 mass% potassium hydroxide aqueous solution (KOH) 1323.5 g
Diethylene glycol 3000g
[0083]
At this time, the current value during the kneading of the planetary mixer was 7A at the initial stage, and then reached a maximum of 12A, and gradually decreased as the kneading continued.
Subsequently, 1000 g of ion-exchanged water was added to the kneaded product in the stirring tank at 20 g / min while continuing kneading. Thereafter, 8000 g of ion-exchanged water was added at 80 g / min while continuing kneading. Furthermore, 2000 g of ion-exchanged water was added to obtain a viscosity-adjusted product, which was taken out.
To 10.00 kg of the taken out viscosity-adjusted product, 3000 g of diethylene glycol and 1600 g of ion-exchanged water were added little by little while stirring with a dispersion stirrer, and dispersed. Further, dispersion was carried out in a bead mill (Nanomill NM-G2L manufactured by Asada Tekko Co., Ltd.) under the same conditions as in Example 1 to obtain a pigment dispersion A3.
The solid content concentration of the pigment dispersion A3 was 24.9%, and the pigment concentration was 14.7%.
[0084]
(Comparative Example 3)
A mixture of the following composition using 34 mass% potassium hydroxide aqueous solution of Example 3 as ion-exchanged water was charged in a 50 L capacity planetary mixer PLM-V-50V (manufactured by Inoue Seisakusho Co., Ltd.), and the jacket was heated. Kneading is carried out at a low speed (rotation speed: 21 rpm, revolution speed: 14 rpm) until the content temperature reaches 60 ° C., and after the content temperature reaches 60 ° C., high speed (rotation speed: 35 rpm, revolution speed) : 24 rpm), and kneading was continued.
[0085]
Resin T 3000g
NOVOPERM YELLOW H2G (Pigment Yellow 120)
(Clariant Japan Co., Ltd.) 5000g
Ion exchange water 1323.5g
Diethylene glycol 3000g
[0086]
The load current value of the planetary mixer was 6A at the start of high speed. Kneading at high speed was performed for 30 minutes, and then 2000 g of diethylene glycol was added at 50 g / min. During that time, the load current value was 8 A and stabilized. After kneading for 1 hour in this state, a mixed solution of diethylene glycol / ion exchanged water = 3000 g / 3500 g was added at 100 g / min. After completion of the addition of the mixed solution, kneading was continued for 30 minutes, and the viscosity-adjusted product was taken out.
To 10 kg of this viscosity-adjusted product, 960 g of diethylene glycol, 3833 g of ion-exchanged water, and 635.6 g of 34 mass% KOH aqueous solution were added little by little using a dispersion stirrer to form a dispersion.
The obtained dispersion was dispersed in a bead mill in exactly the same manner as in Example 3. However, the liquid feed pressure to the disperser increased, and the liquid could not be fed at 500 ml / min. Dispersion was carried out by lowering to obtain a pigment dispersion B3.
The solid content concentration of the pigment dispersion B3 was 26.5% by mass, and the pigment concentration was 15.7% by mass.
[0087]
Example 4
A mixture of the following composition was charged into a planetary mixer PLM-V-50V (made by Inoue Seisakusho Co., Ltd.) with a capacity of 50 L, the jacket was heated, and the speed was low (rotation speed: 21 rpm) until the content temperature reached 60 ° C. Kneading was performed at a revolution speed of 14 rpm, and after the temperature of the contents reached 60 ° C., the speed was changed to a high speed (35 rpm, revolution speed: 24 rpm) and the kneading was continued.
[0088]
Resin S 1500g
Fast Yellow 7413 (Pigment Yellow 74)
(Sanyo Color Co., Ltd.) 5000g
34 mass% potassium hydroxide aqueous solution (KOH) 670 g
Diethylene glycol 2400g
[0089]
At this time, the current value during the kneading of the planetary mixer was 7A at the initial stage, and then reached a maximum of 14A, and gradually decreased as the kneading continued. Kneading was continued for 3 hours in this state. Subsequently, 1000 g of ion-exchanged water was added to the kneaded product in the stirring tank at 20 g / min while continuing kneading. Thereafter, 7000 g of ion-exchanged water was added at 80 g / min while kneading was continued. Furthermore, 2000 g of ion-exchanged water was added to obtain a viscosity-adjusted product, which was taken out.
To 10.00 kg of the taken out viscosity-adjusted product, 1300 g of diethylene glycol and 2140 g of ion-exchanged water were added little by little while stirring with a dispersion stirrer, and dispersed. Further, the dispersion was carried out with a bead mill (Nanomill NM-G2L manufactured by Asada Tekko Co., Ltd.) under the same conditions as in Example 1 to obtain a pigment dispersion A4.
The solid content concentration of the pigment dispersion A4 was 25.6%, and the pigment concentration was 19.0%.
[0090]
(Comparative Example 4)
A mixture of the following composition was charged into a planetary mixer PLM-V-50V (made by Inoue Seisakusho Co., Ltd.) with a capacity of 50 L, the jacket was heated, and the speed was low (rotation speed: 21 rpm) until the content temperature reached 60 ° C. Kneading was performed at a revolution speed of 14 rpm, and after the temperature of the contents reached 60 ° C., the speed was changed to a high speed (35 rpm, revolution speed: 24 rpm) and the kneading was continued.
[0091]
Resin S 1500g
Fast Yellow 7413 (Pigment Yellow 74)
(Sanyo Color Co., Ltd.) 5000g
Ion exchange water 670g
Diethylene glycol 2400g
[0092]
The load current value of the planetary mixer was 6A at the start of high speed. Kneading at high speed was performed for 3 hours, and 1000 g of ion-exchanged water was added at 20 g / min while continuing kneading. Thereafter, 7000 g of ion-exchanged water was added at 80 g / min while continuing kneading. Furthermore, 2000 g of ion-exchanged water was added to obtain a viscosity-adjusted product, which was taken out.
To 10 kg of this viscosity-adjusted product, 342 g of 34 mass% KOH aqueous solution was added using a dispersion stirrer and stirred for 10 minutes. Further, 1300 g of diethylene glycol and 1798 g of ion-exchanged water were added and stirring was continued for 3 hours to form a dispersion. Undissolved kneaded material was observed in the stirring tank.
The obtained dispersion was dispersed in a bead mill in exactly the same manner as in Example 1, but the liquid feed pressure to the disperser increased and the liquid could not be fed at 500 ml / min. The dispersion was carried out by lowering, and a pigment dispersion B4 was obtained.
The solid content concentration of the pigment dispersion B4 was 22.4% by mass, and the pigment concentration was 16.6% by mass.
[0093]
(Example 5)
A mixture of the following composition was charged into a planetary mixer PLM-V-50V (made by Inoue Seisakusho Co., Ltd.) with a capacity of 50 L, the jacket was heated, and the speed was low (rotation speed: 21 rpm) until the content temperature reached 60 ° C. Kneading was performed at a revolution speed of 14 rpm, and after the temperature of the contents reached 60 ° C., the speed was changed to a high speed (35 rpm, revolution speed: 24 rpm) and the kneading was continued.
[0094]
Resin S 1500g
Ink Jet Yellow 4G VP2532 (Pigment Yellow 155)
(Clariant Japan Co., Ltd.) 5000g
34 mass% potassium hydroxide aqueous solution (KOH) 670 g
Diethylene glycol 1500g
[0095]
At this time, the current value during the kneading of the planetary mixer was 7A at the initial stage, and then reached a maximum of 13A, and gradually decreased as the kneading continued. Kneading was continued for 3 hours in this state. Subsequently, 1000 g of ion-exchanged water was added to the kneaded product in the stirring tank at 20 g / min while continuing kneading. Thereafter, 5000 g of ion-exchanged water was added at 80 g / min while kneading was continued. Furthermore, 2000 g of ion-exchanged water was added to obtain a viscosity-adjusted product, which was taken out.
To 10.00 kg of the taken out viscosity-adjusted product, 1756 g of diethylene glycol and 4005 g of ion-exchanged water were added little by little while stirring with a dispersion stirrer, and dispersed. Further, dispersion was carried out with a bead mill (Nanomill NM-G2L manufactured by Asada Tekko Co., Ltd.) under the same conditions as in Example 1 to obtain pigment dispersion A5.
The solid content concentration of the pigment dispersion A5 was 23.2%, and the pigment concentration was 17.2%.
[0096]
(Comparative Example 5)
A mixture of the following composition was charged into a planetary mixer PLM-V-50V (made by Inoue Seisakusho Co., Ltd.) with a capacity of 50 L, the jacket was heated, and the speed was low (rotation speed: 21 rpm) until the content temperature reached 60 ° C. Kneading was performed at a revolution speed of 14 rpm, and after the temperature of the contents reached 60 ° C., the speed was changed to a high speed (35 rpm, revolution speed: 24 rpm) and the kneading was continued.
[0097]
Resin S 1500g
Ink Jet Yellow 4G VP2532 (Pigment Yellow 155)
(Clariant Japan Co., Ltd.) 5000g
Ion exchange water 670g
Diethylene glycol 1500g
[0098]
The load current value of the planetary mixer was 6A at the start of high speed. Kneading at high speed was performed for 3 hours, and 1000 g of ion-exchanged water was added at 20 g / min while continuing kneading. Thereafter, 5000 g of ion-exchanged water was added at 80 g / min while kneading was continued. Furthermore, 2000 g of ion-exchanged water was added to obtain a viscosity-adjusted product, which was taken out.
To 10 kg of this viscosity-adjusted product, 342 g of a 34 mass% KOH aqueous solution was added using a dispersion stirrer and stirred for 10 minutes. Further, 1756 g of diethylene glycol and 3663 g of ion-exchanged water were added and stirring was continued for 3 hours to form a dispersion. Undissolved kneaded material was observed in the stirring tank.
The obtained dispersion was dispersed in a bead mill in exactly the same manner as in Example 1, but the liquid feed pressure to the disperser increased and the liquid could not be fed at 500 ml / min. Dispersion was carried out by lowering to obtain a pigment dispersion B5.
The solid content concentration of the pigment dispersion B5 was 21.8% by mass, and the pigment concentration was 16.2% by mass.
[0099]
[Table 2]

[0100]
(Evaluation of aqueous pigment dispersion)
For the pigment dispersions of Examples and Comparative Examples obtained as described above, the concentration was adjusted by adding ion-exchanged water so that the pigment concentration was 14.5% by mass.
The particle size of the pigment dispersion with the pigment concentration adjusted was measured with a Microtrac UPA particle size analyzer (Leeds & Northrup). At that time, the particle size measurement sample was appropriately diluted with ion-exchanged water so that the particle size could be measured.
In addition, a very small amount of the prepared pigment dispersion is collected on a slide glass, and a cover glass is placed so as not to entrain air in the dispersion droplets on the slide glass. Microscopic observation with transmitted light was performed at a magnification, and coarse particles were observed.
The results are shown in Table 3.
[0101]
[Table 3]

[0102]
From the particle diameter of the dispersion and the results of microscopic observation, in the examples according to the present invention, the conventional method is a method of a comparative example in which a pigment and a resin are kneaded without adding a basic compound and then dispersed in a bead mill. It was found that by adding a basic compound and kneading, the particle size can be remarkably reduced, and the remaining amount of coarse particles can be drastically reduced.
[0103]
(Evaluation of dispersion stability (storage stability))
The pigment dispersions of Examples and Comparative Examples were adjusted by adding ion-exchanged water so that the pigment concentration was 14.5%, respectively, in the same manner as the evaluation of the dispersions.
The dispersion with the pigment concentration adjusted is tightly sealed in a glass container such as a screw tube, and a one-week heating test is performed in a 60 ° C thermostatic chamber. The particle size changes before and after the heating test and the presence or absence of sediment are dispersed. The dispersion stability was evaluated by visually observing the liquid state. The results are shown in Table 4.
[0104]
[Table 4]

[0105]
The dispersion was stored at a constant temperature, and the results of observing the change in average particle size and the presence or absence of precipitates showed that, in the examples according to the present invention, a basic compound was added to the conventional method of pigment and resin. Compared with the method of the comparative example in which the mixture is not kneaded and then dispersed in the bead mill, it is clear that the average particle size does not increase, and the occurrence of sediment is not observed. It was found that the dispersion stability was better.
[0106]
(Adjustment of ink composition)
The obtained dispersions A1, A2, A3, A4, A5, B1, B2, B3, B4, and B5 were adjusted with the following composition (Table 5), and ink compositions AI1, AI2, AI3 having a pigment concentration of 4.0% by mass AI4, AI5, BI1, BI2, BI3, BI4 and BI5 were obtained.
[0107]
[Table 5]

*: Sanyo Chemical (unit: part)
[0108]
(Print test)
The obtained ink composition was mounted on NOVAJET PRO manufactured by ENCAD, and a printing test was performed.
Specifically, solid printing and fine line printing were performed on 4 sheets of A4 printing paper (Yupo inkjet dedicated paper), and the ink ejection state was confirmed.
The results are shown in Table 6.
[0109]
[Table 6]

[0110]
A: Uniform solid printing for all printing samples, ejection failure even in thin line portions, no printing position deviation.
○: Uniform solid printing in all print samples, no discharge failure in the thin line portion, but slight print position deviation is seen.
(Triangle | delta): The density nonuniformity by discharge failure is seen by solid printing, and the printing omission by discharge failure is partially seen also by a thin line part.
X: Density unevenness due to ejection failure is remarkable, and the image is faint. Even in the thin line part, printing omission due to ejection failure is remarkable.
[0111]
From the results of Table 6, it can be seen that the embodiment of the present invention has a large difference in the ink discharge situation compared to the comparative example, and the embodiment of the present invention has a significantly superior discharge stability.
[0112]
【The invention's effect】
An aqueous yellow pigment dispersion and ink composition having good long-term storage stability, in which the yellow pigment was stably dispersed (good dispersion stability) and maintained even during long-term storage, were obtained.
Also provided are a method for producing an aqueous yellow pigment dispersion and ink composition having a short production time such as dispersion time and high production efficiency, and a method for producing an aqueous yellow pigment dispersion and ink composition having a high yield. In particular, it was possible to obtain an ink composition for ink jet recording excellent in ejection characteristics.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an example of the configuration of a planetary mixer.
FIG. 2 is a partially enlarged view of a planetary mixer.
FIG. 3 is an explanatory diagram showing the trajectory of a stirring blade in a planetary mixer.
[Explanation of symbols]
1 .... Agitation tank
2 ···· Upper part of stirring tank
3 .. Lower part of stirring tank
4 and 5 ... stirring blades
6 .... Rotor

Claims (16)

A mixture containing a resin having an anionic group, a yellow pigment, an alkali metal hydroxide, and 10 to 50% by mass of a water-soluble organic solvent in the total mixture is used for a solid or semi-solid aqueous yellow pigment dispersion. method of manufacturing a kneaded product was prepared, the water-soluble organic solvent is water-based yellow pigment dispersion for kneaded product, wherein polyhydric alcohols der Rukoto. The kneaded product for an aqueous yellow pigment dispersion according to claim 1, wherein the polyhydric alcohol used as the water-soluble organic solvent functions as an anti-drying agent when used in an aqueous yellow pigment dispersion. Manufacturing method. The method for producing a kneaded product for an aqueous yellow pigment dispersion according to claim 1, wherein the water-soluble organic solvent is a glycol. The method for producing a kneaded product for an aqueous yellow pigment dispersion according to any one of claims 1 to 3 , wherein the yellow pigment is an insoluble azo pigment. The method for producing a kneaded product for an aqueous yellow pigment dispersion according to any one of claims 1 to 4, wherein a solid content in the kneaded product for the aqueous yellow pigment dispersion is 50 to 80% by mass. Aqueous yellow pigment dispersion for kneaded product according to any one of the water-based yellow pigment dispersion for claims 1 to 5 weight ratio of the resin / yellow pigment kneaded material is 1 / 10-6 / 1 0 Manufacturing method. The method for producing an aqueous yellow pigment kneaded product according to any one of claims 1 to 6 , wherein the resin has a glass transition point of 90 ° C or higher. The pigment is C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 120, C.I. I. Pigment yellow 128, C.I. I. Pigment yellow 155, and C.I. I. The method for producing a kneaded product for an aqueous yellow pigment dispersion according to any one of claims 1 to 7 , which is at least one selected from the group consisting of CI Pigment Yellow 180. The method for producing a kneaded material for an aqueous yellow pigment dispersion according to any one of claims 1 to 8 , wherein the kneading is performed so that the mass of the mixture does not substantially change during kneading. For producing a kneaded product. The method for producing a kneaded product for an aqueous yellow pigment dispersion according to any one of claims 1 to 9 , wherein the kneaded product for an aqueous yellow pigment dispersion is kneaded using a kneader having a stirring tank and a stirring blade. Production method. The method for producing a kneaded product for an aqueous yellow pigment dispersion according to claim 10 , wherein the kneader is a planetary mixer. A step of obtaining a kneaded product for an aqueous yellow pigment dispersion by the method for producing a kneaded product for an aqueous yellow pigment dispersion according to any one of claims 1-11, and the kneaded product for an aqueous yellow pigment dispersion is dissolved in water. dispersed in sex solvent, have a obtaining a water-based yellow pigment dispersion, a water-soluble organic solvent for dispersing the water-based yellow pigment dispersion for kneaded product of an aqueous yellow pigment dispersion having a polyhydric alcohol Production method. The method of manufacturing a water-based yellow pigment dispersion according to claim 1 2, claim 10 or by the method for producing a water-based yellow pigment dispersion for kneaded product according to 11, an aqueous yellow pigment dispersion for kneaded product in a stirred tank And a step of adjusting the viscosity of the aqueous yellow pigment dispersion kneaded material in the stirring tank by adding a water-soluble solvent to the aqueous yellow pigment dispersion kneaded material in the stirring tank. Yes, and manufacturing method of the water-soluble organic solvent for dispersing the water-based yellow pigment dispersion for kneaded product of the polyhydric alcohols der Ru-based yellow pigment dispersion. The aqueous yellow pigment dispersion kneaded product according to claim 12 or 13, wherein the water-soluble organic solvent in which the aqueous pigment dispersion kneaded product is dispersed is glycols. The method of manufacturing a water-based yellow pigment dispersion according to any one of claims 12 to 14, the water-based yellow pigment dispersion for kneaded product, in a water-soluble solvent using a dispersing machine using media dispersion A method for producing a water-based yellow pigment dispersion, characterized by comprising: Of claim 1 2-1 5 or the ink composition to produce a aqueous yellow pigment dispersion obtained by the production method of the water-based yellow pigment dispersion was diluted with a water-soluble solvent ink composition according to one of Production method.

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