JP4753600B2 - Pigment dispersion, method for producing the same, ink jet ink using the same, and image forming method using the same - Google Patents

Description

  The present invention relates to a pigment dispersion, a method for producing the same, an ink jet ink using the same, an ink cartridge using the same, an image forming body, and an image forming method. In the production of inkjet recording ink dispersed and used, pigment-based inkjet pigment dispersion excellent in ejection stability and production method thereof, inkjet ink using the pigment dispersion, ink cartridge using the ink, The present invention relates to an image forming body and an image forming method.

  The inkjet recording method is easy to make full color because the process is simpler than other recording methods, and there is an advantage that a high-resolution image can be obtained even with an apparatus having a simple configuration. As ink-jet inks, dye-based inks in which various water-soluble dyes are dissolved in water or a mixture of water and an organic solvent are used. Dye-based inks have excellent color clarity but are not resistant to light. There was a disadvantage that was inferior in nature.

  On the other hand, pigment-based inks in which carbon black and various organic pigments are dispersed are actively studied because they are superior in light resistance compared to dye-based inks. The pigment ink is generally prepared by preparing a dispersion in which a coloring material and a dispersant are predispersed in an aqueous solvent body such as water or alcohol, and then using a media-type disperser such as a sand mill. It is adjusted by carrying out a dispersion step of dispersing to a predetermined concentration and then diluting to a predetermined concentration.

  On the other hand, in recent years, it has been desired to reduce the particle diameter of ink in order to improve the fineness of an image. For this purpose, pigments are required to have finer particles, transparency, and sharper particle size distribution, but there is a drawback that the dispersion stability is poor in terms of quality control.

  For example, in Japanese Examined Patent Publication No. 57-56944 (Patent Document 1), a method of pre-kneading with a sand mill or the like and then dispersing with a roll mill, and in Japanese Unexamined Patent Publication No. 7-198933 (Patent Document 2), a method using a two-roll mill. Has been proposed. However, the water-dispersed pigments obtained by these methods still have a problem that the pigment particles still contain many coarse particles, a sharp particle size distribution cannot be obtained, and the stability over time is insufficient.

In addition, the present applicant previously described in Japanese Patent Application Laid-Open Nos. 2004-2715 and 2004-169008 (Patent Documents 3 and 4) in a pigment dispersion suitable for ink-jet ink, β -Proposed using naphthyl ether.
However, there has been a problem that the pigment particles have a large sedimentation and viscosity change during ink storage, and ejection during printing is unstable.

Japanese Patent Publication No.57-56944 JP-A-7-198933 JP 2004-2715 A JP 2004-169008 A

  The present invention has been made in view of the above circumstances, and includes a pigment dispersion containing fine pigment particles having a sharp particle size distribution and excellent in temporal stability, a method for producing the same, and a pigment using the same It is an object of the present invention to provide a technique relating to an inkjet ink, an image forming body using the ink, an ink cartridge, and an image forming method using the ink.

  As a result of intensive studies, the present inventors have found that the above problems can be solved by adding and dispersing a specific compound at the time of pigment dispersion and thereby specifying the dispersion state of the pigment, thereby completing the present invention. It came to.

That is, the said subject is solved by following (1)-(31) of this invention.
(1) “A method for producing a pigment dispersion, wherein at least a pigment, water, polyoxyethylene, and a compound represented by the following general formula (1) are mixed and dispersed.

（式中、Ｒは炭素数１〜２０のアルキル基、アリール基、アラルキル基を表わし、ｌは０〜７の整数を表わし、ｎは２０〜２００の整数を表わす。）」；
（２）「前記一般式（１）で示されている化合物がＰＯＥ（ｎ＝４０）β−ナフチルエーテルであることを特徴とする前記（１）に記載の顔料分散液の製造方法」；
（３）「前記ポリオキシエチレンの重合度が３０〜１２０であることを特徴とする前記（１）又は（２）に記載の顔料分散液の製造方法」；
（４）「前記ポリオキシエチレンが、前記一般式（１）で示されている化合物に対し０．１〜１０重量％含有することを特徴とする前記（１）〜（３）のいずれかに記載の顔料分散液の製造方法」；
（５）「前記顔料分散液中の該顔料の濃度が５〜５０重量％であることを特徴とする前記（１）〜（４）のいずれかに記載の顔料分散液の製造方法」；
（６）「前記顔料分散液中の、該顔料粒子の平均粒子径（Ｄ５０）が１５０ｎｍ以下であり、該顔料粒子の粒度分布に於ける粒子径標準偏差が平均粒子径（Ｄ５０）より小さいことを特徴とする前記（１）〜（５）のいずれかに記載の顔料分散液の製造方法」；
（７）「前記顔料の内、ブラック顔料がカーボンブラックであることを特徴とする前記（１）〜（６）のいずれかに記載の顔料分散液の製造方法」；
（８）「前記顔料の内、イエロー顔料がＰｉｇ．Ｙｅｌｌｏｗ1、2、3、12、13、14、16、17、73、74、75、83、93、95、97、98、114、120、128、129、138、150、151、154、155、174、180のうちの少なくとも一種であることを特徴とする前記（１）〜（６）のいずれかに記載の顔料分散液の製造方法」；
（９）「前記顔料の内、マゼンタ顔料がＰｉｇ．Ｒｅｄ5、7、12、48（Ｃａ）、48（Ｍｎ）、57（Ｃａ）、57：1、112、122、123、146、168、176、184、185、202、Ｐｉｇ．Ｖｉｏｌｅｔ19のうちの少なくとも一種であることを特徴とする前記（１）〜（６）のいずれかに記載の顔料分散液の製造方法」；
（１０）「前記顔料の内、シアン顔料がＰｉｇ．Ｂｌｕｅ1、2、3、15、15：3、1：：4、16、22、60、63、66のうちの少なくとも一種であることを特徴とする前記（１）〜（６）のいずれかに記載の顔料分散液の製造方法」；
（１１）「少なくとも顔料、水、ポリオキシエチレン、及び下記一般式（１）で示される化合物を含有することを特徴とする顔料分散液。

(In the formula, R represents an alkyl group having 1 to 20 carbon atoms, an aryl group or an aralkyl group, l represents an integer of 0 to 7, and n represents an integer of 20 to 200).
(2) “The method for producing a pigment dispersion according to (1) above, wherein the compound represented by the general formula (1) is POE (n = 40) β-naphthyl ether”;
(3) "The method for producing a pigment dispersion according to (1) or (2) above, wherein the degree of polymerization of the polyoxyethylene is 30 to 120";
(4) In any one of the above (1) to (3), the polyoxyethylene is contained in an amount of 0.1 to 10% by weight based on the compound represented by the general formula (1). A process for producing the pigment dispersion according to the description "
(5) “The method for producing a pigment dispersion according to any one of (1) to (4) above, wherein the concentration of the pigment in the pigment dispersion is 5 to 50% by weight”;
(6) “In the pigment dispersion, the average particle size (D50) of the pigment particles is 150 nm or less, and the particle size standard deviation in the particle size distribution of the pigment particles is smaller than the average particle size (D50). The process for producing a pigment dispersion according to any one of (1) to (5) above,
(7) “The method for producing a pigment dispersion according to any one of (1) to (6) above, wherein the black pigment is carbon black among the pigments”;
(8) “Of the pigments, the yellow pigment is Pig. Yellow1, 2, 3, 12, 13, 14, 16, 17, 73, 74, 75, 83, 93, 95, 97, 98, 114, 120, 128, 129, 138, 150, 151, 154, 155, 174, 180 is a method for producing a pigment dispersion according to any one of (1) to (6) above, ;
(9) “Of the above pigments, the magenta pigment is Pig. Red 5, 7, 12, 48 (Ca), 48 (Mn), 57 (Ca), 57: 1, 112, 122, 123, 146, 168, 176 184, 185, 202, Pig.Violet19, the method for producing a pigment dispersion according to any one of (1) to (6) above,
(10) “Of the pigments, the cyan pigment is at least one of Pig. Blue 1, 2, 3, 15, 15: 3, 1 :: 4, 16, 22, 60, 63, 66. A method for producing a pigment dispersion according to any one of (1) to (6) above;
(11) “A pigment dispersion characterized by containing at least a pigment, water, polyoxyethylene, and a compound represented by the following general formula (1):

（式中、Ｒは炭素数１〜２０のアルキル基、アリール基、アラルキル基を表わし、ｌは０〜７の整数を表わし、ｎは２０〜２００の整数を表わす。）」；
（１２）「前記一般式（１）で示されている化合物がＰＯＥ（ｎ＝４０）β−ナフチルエーテルであることを特徴とする前記（１１）に記載の顔料分散液」；
（１３）「前記ポリオキシエチレンの重合度が３０〜１２０であることを特徴とする前記（１１）又は（１２）に記載の顔料分散液」；
（１４）「前記ポリオキシエチレンが、前記一般式（１）で示されている化合物に対し０．１〜１０重量％含有することを特徴とする前記（１１）〜（１３）のいずれかに記載の顔料分散液」；
（１５）「前記顔料分散液中の該顔料の濃度が５〜５０重量％であることを特徴とする前記（１１）〜（１４）のいずれかに記載の顔料分散液」；
（１６）「前記顔料分散液中の、該顔料粒子の平均粒子径（Ｄ５０）が１５０ｎｍ以下であり、該顔料粒子の粒度分布に於ける粒子径標準偏差が平均粒子径（Ｄ５０）より小さいことを特徴とする前記（１１）〜（１５）のいずれかに記載の顔料分散液」；
（１７）「前記顔料の内、ブラック顔料がカーボンブラックであることを特徴とする前記（１１）〜（１６）のいずれかに記載の顔料分散液」；
（１８）「前記顔料の内、イエロー顔料がＰｉｇ．Ｙｅｌｌｏｗ1、2、3、12、13、14、16、17、73、74、75、83、93、95、97、98、114、120、128、129、138、150、151、154、155、174、180のうちの少なくとも一種であることを特徴とする前記（１１）〜（１６）のいずれかに記載の顔料分散液」；
（１９）「前記顔料の内、マゼンタ顔料がＰｉｇ.Ｒｅｄ5、7、12、48（Ｃａ）、48（Ｍｎ）、57（Ｃａ）、57：1、112、122、123、146、168、176、184、185、202、Ｐｉｇ．Ｖｉｏｌｅｔ19のうちの少なくとも一種であることを特徴とする前記（１１）〜（１６）のいずれかに記載の顔料分散液」；
（２０）「前記顔料の内、シアン顔料がＰｉｇ．Ｂｌｕｅ1、2、3、15、15：3、15：4、16、22、60、63、66のうちの少なくとも一種であることを特徴とする前記（１１）〜（１６）のいずれかに記載の顔料分散液」；
（２１）「前記（１１）〜（２０）のいずれかに記載の顔料分散液に、水溶性有機溶剤、界面活性剤、防腐剤、防黴剤からなる群から選択される少なくとも一つの添加剤を更に含有することを特徴とするインクジェット用インク」；
（２２）「顔料の濃度が１〜１５重量％であることを特徴とする前記（２１）に記載のインクジェット用インク」；
（２３）「前記（２１）又は（２２）に記載のインクジェット用インクを収容したことを特徴とするインクカートリッジ」；
（２４）「画像形成装置に着脱可能であることを特徴とする前記（２３）に記載のインクカートリッジ」；
（２５）「前記（２１）又は（２２）に記載のインクジェット用インクを用いて受容体に画像が形成されていることを特徴とする画像形成体」；
（２６）「前記受容体が紙であることを特徴とする前記（２５）に記載の画像形成体」；
（２７）「前記（２１）又は（２２）に記載のインクジェット用インクを用いて受容体に画像を形成することを特徴とする画像形成方法」；
（２８）「前記（２１）又は（２２）に記載のインクジェット用インクを画像形成装置から前記受容体へ吐出させることを特徴とする前記（２７）に記載の画像形成方法」；
（２９）「前記画像形成装置が、インクジェットプリンターであることを特徴とする前記（２８）に記載の画像形成方法」；
（３０）「前記インクジェットプリンターが、ピエゾ方式のインクジェットプリンターであることを特徴とする前記（２９）に記載の画像形成方法」；
（３１）「前記インクジェットプリンターが、サーマル方式のインクジェットプリンターであることを特徴とする前記（２９）に記載の画像形成方法」。

(In the formula, R represents an alkyl group having 1 to 20 carbon atoms, an aryl group or an aralkyl group, l represents an integer of 0 to 7, and n represents an integer of 20 to 200).
(12) “The pigment dispersion according to (11) above, wherein the compound represented by the general formula (1) is POE (n = 40) β-naphthyl ether”;
(13) "The pigment dispersion according to (11) or (12) above, wherein the degree of polymerization of the polyoxyethylene is 30 to 120";
(14) In any one of the above (11) to (13), the polyoxyethylene is contained in an amount of 0.1 to 10% by weight based on the compound represented by the general formula (1). Described pigment dispersions ";
(15) "The pigment dispersion according to any one of (11) to (14) above, wherein a concentration of the pigment in the pigment dispersion is 5 to 50% by weight";
(16) “In the pigment dispersion, the average particle diameter (D50) of the pigment particles is 150 nm or less, and the particle diameter standard deviation in the particle size distribution of the pigment particles is smaller than the average particle diameter (D50). The pigment dispersion according to any one of (11) to (15) above,
(17) "The pigment dispersion according to any one of (11) to (16) above, wherein the black pigment is carbon black among the pigments";
(18) “Of the pigments, the yellow pigment is Pig. Yellow1, 2, 3, 12, 13, 14, 16, 17, 73, 74, 75, 83, 93, 95, 97, 98, 114, 120, 128, 129, 138, 150, 151, 154, 155, 174, 180, which is at least one of the pigment dispersions according to any one of (11) to (16) above;
(19) “Of the pigments, magenta pigments are Pig. Red 5, 7, 12, 48 (Ca), 48 (Mn), 57 (Ca), 57: 1, 112, 122, 123, 146, 168, 176 , 184, 185, 202, Pig. Violet 19, the pigment dispersion according to any one of (11) to (16) above,
(20) “Among the pigments, the cyan pigment is at least one of Pig. Blue 1, 2, 3, 15, 15: 3, 15: 4, 16, 22, 60, 63, 66. The pigment dispersion according to any one of (11) to (16) above;
(21) “At least one additive selected from the group consisting of a water-soluble organic solvent, a surfactant, a preservative, and an antifungal agent in the pigment dispersion according to any one of (11) to (20). An ink-jet ink further comprising:
(22) “Inkjet ink according to (21) above, wherein the pigment concentration is 1 to 15% by weight”;
(23) "Ink cartridge characterized by containing ink jet ink according to (21) or (22)";
(24) “The ink cartridge according to (23), which is detachable from the image forming apparatus”;
(25) "Image forming body, wherein an image is formed on a receiver using the ink jet ink according to (21) or (22)";
(26) "The image forming body according to (25) above, wherein the receptor is paper";
(27) "An image forming method comprising forming an image on a receptor using the ink jet ink according to (21) or (22)";
(28) "The image forming method according to (27) above, wherein the inkjet ink according to (21) or (22) is ejected from an image forming apparatus to the receptor";
(29) "The image forming method according to (28), wherein the image forming apparatus is an ink jet printer";
(30) "The image forming method according to (29), wherein the inkjet printer is a piezo inkjet printer";
(31) “The image forming method according to (29), wherein the inkjet printer is a thermal inkjet printer”.

According to the present invention, an aqueous pigment dispersion having excellent dispersion stability and stability over time is obtained by including fine pigment particles having a sharp particle size distribution and using a specific dispersant as a pigment dispersion. Ink jet ink using the dispersant can form a vivid image.
Further, according to the present invention, a cartridge containing the ink, an image forming body using the ink, and an image forming method can be provided.

  Hereinafter, the present invention will be described in more detail. As described above, the feature of the present invention relates to a pigment dispersion characterized in that the pigment dispersion contains at least a pigment, water, polyoxyethylene, and a compound represented by the following general formula (1).

（式中、Ｒは炭素数１〜２０のアルキル基、アリール基、アラルキル基を表わし、ｌは０〜７の整数を表わし、ｎは２０〜２００の整数を表わす。）

(In the formula, R represents an alkyl group having 1 to 20 carbon atoms, an aryl group, or an aralkyl group, l represents an integer of 0 to 7, and n represents an integer of 20 to 200.)

  The compound represented by the general formula (1) has good dispersion stability and can be preferably used. n is an integer of 20 to 200, more preferably an integer of 30 to 50. When n is less than 20, the dispersion stability tends to decrease. When n is greater than 200, the viscosity of the dispersion liquid and ink tends to increase. Among these, POE (n = 40) β-naphthyl ether in which n is 40 is more preferable. Here, POE (n = 40) represents that n of the polyoxyethylene moiety in the general formula (1) is 40.

In the compound represented by the general formula (1), it is preferable that the polyoxyethylene moiety is bonded to the β-position of the naphthalene ring.
The R group substituted on the naphthalene ring represents an alkyl group having 1 to 20 carbon atoms, an aryl group, or an aralkyl group.
Examples of the alkyl group having 1 to 20 carbon atoms include a methyl group and an ethyl group.
Examples of the aryl group include a naphthyl group, a phenyl group, and a nonylphenyl group.
Furthermore, examples of the aralkyl group include a benzyl group and a phenethyl group.
Furthermore, the substitution number 1 of R group is 0-7, and 1-4 are preferable. When l is 2 or more, a plurality of R may be the same or different. The position of the naphthalene ring to which the R group and the polyoxyethylene moiety are bonded may be the same ring or / and different rings.

  The amount used is preferably included in a ratio of 0.15 to 1 with respect to the pigment 1 on a weight basis. More preferably, the said ratio is 0.25-1 with respect to the pigment 1. FIG. By adopting such a use amount, the average particle size (D50) can be reduced and the standard deviation of the particle size can be reduced, and thereby pigment dispersion with further excellent saturation, ejection stability and liquid stability. A liquid can be provided. In addition, when the amount used is less than 0.15, the above effect is difficult to achieve, and the storage stability of the pigment dispersion and the ink is inferior, and as a result, nozzle clogging tends to occur easily. The viscosity of the pigment dispersion and the ink tends to be too high, and printing by the inkjet method tends to be difficult.

  The polyoxyethylene used in the pigment dispersion of the present invention can improve the dispersion stability and the vividness of the image, and can be preferably used. More preferably, the degree of polymerization of the oxyethylene monomer is 20 to 120, and more preferably 30 to 100. When n is less than 20, the dispersion stability and liquid stability tend to decrease, and when n is greater than 120, the viscosity of the dispersion and ink tends to increase.

  In the pigment dispersion of the present invention, the concentration of polyoxyethylene is preferably 0.1 to 10% by weight with respect to the compound represented by the general formula (1). If it is less than 0.1% by weight, there is no dispersion stabilizing effect. If it is more than 10% by weight, the viscosity of the pigment dispersion tends to be too high and dispersion tends to be difficult.

  Examples of the pigment used in the pigment dispersion of the present invention include, for example, carbon black produced by a furnace method or a channel method as a black pigment.

  Examples of the yellow pigment include Pigment Yellow 1, Pigment Yellow 2, Pigment Yellow 3, Pigment Yellow 12, Pigment Yellow 13, Pigment Yellow 14, Pigment Yellow 16, Pigment Yellow 17, Pigment Yellow 73, Pigment Yellow 74, Pigment Yellow 75, Pigment Yellow 83, Pigment Yellow 93, Pigment Yellow 95, Pigment Yellow 97, Pigment Yellow 98, Pigment Yellow 114, Pigment Yellow 120, Pigment Yellow 128, Pigment Yellow 129, Pigment Yellow 138, Pigment Yellow 150, Pigment Yellow 151, Pigment Yellow 154, Pigment Yellow 155, Pigment Yellow 180, etc. It is below.

  Examples of magenta pigments include Pigment Red 5, Pigment Red 7, Pigment Red 12, Pigment Red 48 (Ca), Pigment Red 48 (Mn), Pigment Red 57 (Ca), Pigment Red 57: 1, Pigment Red 112, Pigment. Red 122, pigment red 123, pigment red 168, pigment red 184, pigment red 202, pigment violet 19, and the like.

  Further, as cyan pigments, Pigment Blue 1, Pigment Blue 2, Pigment Blue 3, Pigment Blue 15, Pigment Blue 15: 3, Pigment Blue 15: 4, Pigment Blue 16, Pigment Blue 22, Pigment Blue 60, Bat Blue 4, Examples include Bat Blue 60.

  Among these, by using Pigment Yellow 74 as a yellow pigment, Pigment Red 122, Pigment Violet 19 as a magenta pigment, and Pigment Blue 15: 3 as a cyan pigment, an ink for ink jet ink having excellent color tone and light fastness and balanced can be obtained. Obtainable.

  In the pigment dispersion of the present invention, the pigment concentration is preferably 5 to 50% by weight. If it is less than 2% by weight, the productivity is inferior, and if it is more than 50% by weight, the viscosity of the pigment dispersion tends to be too high to make dispersion difficult.

  In the present invention, the average particle diameter (D50) of the pigment particles is preferably 150 nm or less, and the particle diameter standard deviation in the particle size distribution of the pigment particles is preferably smaller than the average particle diameter (D50). The average particle diameter (D50) of the pigment particles is preferably 100 nm or less, and more preferably 50 nm or less. When the average particle diameter (D50) exceeds 150 nm, the saturation is poor. In addition, although the average particle diameter (D50) in this invention can be measured by a conventional method, it can be measured, for example using the Nikkiso Co., Ltd. particle size analyzer UPA150. Further, the standard deviation of the particle diameter in the present invention can be measured by a conventional method, but this is also a measured value sd obtained by measuring using, for example, a particle size analyzer UPA150 manufactured by Nikkiso Co., Ltd. Can do.

  The average particle size (D50) and particle size standard deviation can be controlled by the peripheral speed of the rotating part of the disperser, the dispersion time, the dispersion flow rate, and the dispersion temperature when the pigment is dispersed using a disperser. In this case, when the average particle diameter (D50) of the pigment particles is 150 nm or less and the particle diameter standard deviation in the particle size distribution of the pigment particles is smaller than the average particle diameter (D50), the peripheral speed of the rotating part of the disperser is If it is too high, the pigment dispersion tends to agglomerate, and if it is too low, the dispersion efficiency is poor and the productivity is lowered, so that it is preferably 6 m / s to 13 m / s. Further, it is desirable that the dispersion is completed when the average particle size change in the dispersion time in the media mill for 5 minutes is less than 2%.

  Furthermore, the dispersion flow rate is preferably 300 ml / min or more, and if it is less than 300 ml / min, the dispersion temperature rises, which is not preferable for dispersion stability. Further, the circulation type dispersion is not preferable because the particle diameter standard deviation tends to be large in short-time dispersion. Further, the dispersion temperature is preferably less than 10 ° C during dispersion, and more preferably 4 to 8 ° C is good in dispersion stability. Moreover, when using a bead mill as a disperser demonstrated below, it is controllable by adjusting the magnitude | size of a dispersion medium (bead). In this case, in order to make the average particle diameter (D50) 100 nm or less, it is preferable to make the beads about 0.1 mm to 1.0 mm, and more preferably 0.1 mm to 0.5 mm. Moreover, the particle diameter standard deviation in this invention can be made smaller than an average particle diameter (D50) by this method.

  The pigment dispersion of the present invention includes the pigment, the compound represented by the general formula (1), polyoxyethylene, water, and various additives as necessary, such as a sand mill, a ball mill, a roll mill, a bead mill, a nanomizer, and a homogenizer. It is obtained by dispersing with a disperser. At this time, the amount of the compound represented by the general formula (1), which is a nonionic surfactant, is set to a ratio of 0.15 to 1 with respect to the pigment 1 based on the weight as described above, and the wet dispersion treatment is performed. It is preferable to adopt. In the present invention, the wet dispersion treatment refers to the pigment, the compound represented by the general formula (1), polyoxyethylene, water, and a mixture of various additives as necessary, the sand mill, ball mill, roll mill, bead mill, nanomizer. It is a process of pulverizing and dispersing by a so-called wet dispersion method using a homogenizer or the like.

  The inkjet ink according to the present invention may further include at least one additive selected from the group consisting of a water-soluble organic solvent, a surfactant, a preservative, and an antifungal agent. Ink-jet inks and pigments capable of dissolving necessary organic substances by further containing at least one additive selected from components consisting of water-soluble organic solvents, surfactants, preservatives, and antifungal agents Ink jet ink having further improved dispersibility of the dispersoid containing particles, and ink jet ink having properties resulting from an additive having antiseptic and antifungal effects can be provided.

  Specific examples of additives include alcohols such as methanol, ethanol, 1-propanol, and 2-propanol as water-soluble organic media, polyhydric alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, and glycerin, N -Pyrrolidone derivatives such as methylpyrrolidone and 2-pyrrolidone, ketones such as acetone and methylethylketone, alkanolamines such as monoethanolamine, diethanolamine and triethanolamine, nonionic, anionic, cationic and amphoteric surfactants, antiseptics Agents and the like.

The pigment dispersion of the present invention thus obtained can be suitably used particularly as a pigment-based inkjet ink. The pigment-based inkjet ink is prepared by a known method, for example, by stirring and mixing the pigment dispersion of the present invention, water, a water-soluble organic solvent, a surfactant, etc., and filtering coarse particles with a filter, a centrifugal separator, or the like. It is obtained by deaeration accordingly. The pigment concentration of the ink is preferably 1 to 15% by weight. If the amount is less than 1% by weight, the image density is low and the printed image lacks sharpness. If the amount is more than 15% by weight, not only the viscosity of the ink tends to increase but also nozzle clogging tends to occur.
Further, the ink can be blended with a material equivalent to the material described as an additive to the pigment dispersion as required. For example, the content of the water-soluble organic solvent is 0 to 50% by weight, preferably 5 to 40% by weight, and more preferably 10 to 35% by weight with respect to the total amount of the ink.

  The pigment-based inkjet ink of the present invention thus obtained contains, for example, an inkjet recording ink set that forms an image on an image support by superimposing a plurality of different hue inks in order to form a color image. The ink cartridge can be suitably used. The pigment-based inkjet ink of the present invention is a continuous printing method that can form an image with an inkjet printing apparatus that forms an image by discharging (recording) the image on an image support such as paper. An injection type or an on-demand type is mentioned. Examples of the on-demand type include a piezo method, a thermal ink jet method, and an electrostatic method.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited to a present Example. In addition, the number of parts in an Example represents a weight part.

Example 1
Pigment: Carbon black (Mitsubishi Kasei MCF-88) 30 parts POE (n = 100) β-naphthyl ether 15 parts Polyoxyethylene (degree of polymerization = 40) 1.5 parts Distilled water 153.5 parts Premix the above mixture After that, a pigment dispersion liquid (A) was obtained by dispersing for 180 minutes at a peripheral speed of 6 m / s and a liquid temperature of 8 ° C. using 0.3 mm zirconia beads in a disk type bead mill (Shinmaru Enterprises KDL type).

Example 2
Pigment: Pigment Yellow 74 (Yellow Seika Co., Ltd. Yellow No. 43) 30 parts POE (n = 40) β-naphthyl ether 15 parts Polyoxyethylene (degree of polymerization = 50) 0.5 part Distilled water 154.5 parts After premixing, the mixture was dispersed in a disk-type bead mill (Shinmaru Enterprises KDL type) using 0.3 mm zirconia beads for 90 minutes at a peripheral speed of 10 m / s and a liquid temperature of 10 ° C. to obtain a pigment dispersion (B) Got.

Example 3
Pigment: Pigment Red 122
(FASTOGEN SUPER MAGENTA RG, manufactured by Dainippon Ink Co., Ltd.) 30 parts POE (n = 80) β-naphthyl ether 15 parts polyoxyethylene (degree of polymerization = 100) 0.15 parts distilled water 154.85 parts After mixing, it was dispersed in a disk type bead mill (Shinmaru Enterprises KDL type) using 0.3 mm zirconia beads for 180 minutes at a peripheral speed of 13 m / s and a liquid temperature of 8 ° C. to obtain a pigment dispersion (C).

Example 4
Pigment: Pigment Blue 15: 3
(LIONOL BLUE FG-7351, manufactured by Toyo Ink Co., Ltd.) 30 parts POE (n = 40) β-naphthyl ether 23 parts polyoxyethylene (degree of polymerization = 40) 2 parts distilled water 145 parts Disc mixture after premixing the above mixture Was dispersed for 300 minutes at a peripheral speed of 10 m / s and a liquid temperature of 8 ° C. using 0.3 mm zirconia beads in a bead mill (Shinmaru Enterprises KDL type) to obtain a pigment dispersion (D).

Example 5
In Example 3, except that POE (n = 80) β-naphthyl ether was changed to POE (n = 38) α-naphthyl ether, the pigment dispersion (E) was prepared by the same formulation and production method as in Example 3. Obtained.

Comparative Example 1
Pigment: Carbon black (Mitsubishi Kasei MCF-88) 30 parts Polyoxyethylene oleyl ether ammonium sulfate
(Daiichi Kogyo Seiyaku Co., Ltd. Hightenol 18E) 23 parts Distilled water 147 parts After premixing the above mixture, a disk-type bead mill (Shinmaru Enterprises KDL type) used 1.2 mm zirconia beads to obtain a peripheral speed of 15 m / s for 180 minutes at a liquid temperature of 20 ° C. to obtain a pigment dispersion (F).

Comparative Example 2
Pigment: Pigment Yellow 74 (Yellow Seika Chemical Co., Ltd. Yellow No. 43) 30 parts Polyoxyethylene oleyl ether ammonium sulfate
(Daiichi Kogyo Seiyaku Co., Ltd. Hightenol 18E) 23 parts Distilled water 147 parts After premixing the above mixture, a disk-type bead mill (Shinmaru Enterprises KDL type) used 1.2 mm zirconia beads to obtain a peripheral speed of 15 m / s for 90 minutes at a liquid temperature of 20 ° C. to obtain a pigment dispersion (G).

Comparative Example 3
Pigment: Pigment Red 122
(Dainippon Ink, FASTOGEN SUPER MAGENTA RG) 30 parts polyoxyethylene oleyl ether ammonium sulfate
(Daiichi Kogyo Seiyaku Co., Ltd. Hightenol 18E) 23 parts Distilled water 147 parts After premixing the above mixture, a disk-type bead mill (Shinmaru Enterprises KDL type) used 1.2 mm zirconia beads to obtain a peripheral speed of 15 m / s for 180 minutes at a liquid temperature of 20 ° C. to obtain a pigment dispersion (H).

Comparative Example 4
Pigment: Pigment Blue 15: 3
(Toyo Ink Co., Ltd., LIONOL BLUE FG-7351) 30 parts polyoxyethylene oleyl ether ammonium sulfate
(Daiichi Kogyo Seiyaku Co., Ltd. Hytenol 18E) 23 parts Distilled water 147 parts After premixing the above mixture, a disk type bead mill (Shinmaru Enterprises KDL type) used 1.5 mm zirconia beads to obtain a peripheral speed of 20 m / s for 300 minutes at a liquid temperature of 12 ° C. to obtain a pigment dispersion (I).

Comparative Example 5
A pigment dispersion (J) was obtained by the same formulation and production method as in Example 1 except that polyoxyethylene (n = 40) was omitted in Example 1.

  Using the pigment dispersions (A) to (J) obtained by the above method, an ink solution was prepared according to the following ink formulation, stirred for 30 minutes, filtered through a membrane filter with a pore size of 0.8 μm, and vacuum degassed. Ink liquids of Examples (a) to (e) and Comparative Examples (f) to (j) were obtained.

Ink formulation Pigment dispersion (pigment concentration 15% by weight) 40.0 parts Glycerin 7.5 parts Diethylene glycol 22.5 parts 2-ethyl-1,3-hexanediol 3.0 parts 2-pyrrolidone 3.0 parts Polyoxyethylene (3) Alkyl (C13)
Sodium ether acetate 0.45 parts Distilled water 23.55 parts The pigment average particle diameter and standard deviation of the particle diameters of the ink-jet inks (a) to (j) above were measured using a particle size analyzer UPA150 manufactured by Nikkiso Co., Ltd. Measured. The results are shown in Table 1. Further, image vividness, ejection stability, viscosity stability test, and sedimentation degree test were examined according to the following methods. The results are shown in Table 1.

<Vividness of image>
The density or saturation of the printed image was measured using an X-rite densitometer on an inkjet printer EM-930C (piezo method) manufactured by EPSON, and determined as follows. At that time, Xerox 4024 paper (size 32 s, air permeability 21 s) manufactured by Xerox Corporation was used as a recording medium.
When the pigment is carbon black, the density is 1.1 or more, ◯, the density of 0.9 to less than 1.1 is Δ, and the density is less than 0.9.
Pigment Yellow 74 has a saturation of 75 or more as ◯, 70 or more and less than 75 as Δ, and less than 70 as x.
Pigment Red 122 has a saturation of 60 or more as ◯, 55 or more and less than 60 as Δ, and less than 55 as x.
-For Pigment Blue 15: 3, a saturation of 50 or more is indicated by ◯, 48 or more and less than 50 by Δ, and less than 48 by ×.

<Discharge stability>
After sealing in a polyethylene container and leaving at high temperature at 50 ° C. for 7 days, the printing ejection stability was evaluated with an inkjet printer EM-930C (piezo method) manufactured by EPSON and an inkjet printer DeskJet 880C (thermal method) manufactured by HP. The head clogging at the time of printing was evaluated. The head clogging was evaluated as “B”, and the head clogging as “C”.

<Viscosity stability test>
The aqueous pigment dispersion placed in a sealed glass container was placed in a thermostatic bath at 50 ° C. and left to stand for 3 months to check whether there was a change in viscosity. A viscosity change of less than 5% was rated as ◯, and a viscosity change of 5% or more was rated as x.

<Settling test>
The aqueous pigment dispersion obtained for examining the dispersion stability was allowed to stand in a thermostatic chamber at 20 ° C. for 6 months, and the presence or absence of sedimentation of the pigment was confirmed. A state in which separation, water floating or sedimentation occurred even if a little occurred was evaluated as abnormal.

Claims (29)

A method for producing a pigment dispersion, comprising mixing and dispersing at least a pigment, water, a polyoxyethylene having a polymerization degree of 30 to 120 , and a compound represented by the following general formula (1).

(In the formula, R represents an alkyl group having 1 to 20 carbon atoms, an aryl group, or an aralkyl group, l represents an integer of 0 to 7, and n represents an integer of 20 to 200.)   The method for producing a pigment dispersion according to claim 1, wherein the compound represented by the general formula (1) is POE (n = 40) β-naphthyl ether. The method for producing a pigment dispersion according to claim 1 or 2 , wherein the polyoxyethylene is contained in an amount of 0.1 to 10% by weight based on the compound represented by the general formula (1). The method for producing a pigment dispersion according to any one of claims 1 to 3 , wherein the concentration of the pigment in the pigment dispersion is 5 to 50% by weight. The average particle size (D50) of the pigment particles in the pigment dispersion is 150 nm or less, and the particle size standard deviation in the particle size distribution of the pigment particles is smaller than the average particle size (D50). The manufacturing method of the pigment dispersion liquid in any one of Claims 1-4 . The method for producing a pigment dispersion according to any one of claims 1 to 5 , wherein among the pigments, the black pigment is carbon black. Among the pigments, the yellow pigment is Pig. Yellow1, 2, 3, 12, 13, 14, 16, 17, 73, 74, 75, 83, 93, 95, 97, 98, 114, 120, 128, 129, 138, 150, 151, 154, 155, The method for producing a pigment dispersion according to any one of claims 1 to 5 , wherein the pigment dispersion is at least one of 174 and 180. Among the pigments, a magenta pigment is Pig. Red 5, 7, 12, 48 (Ca), 48 (Mn), 57 (Ca), 57: 1, 112, 122, 123, 146, 168, 176, 184, 185, 202, Pig. Method for producing a pigment dispersion liquid according to any one of claims 1 to 5, characterized in that at least one of Violet 19. Among the pigments, the cyan pigment is Pig. The pigment according to any one of claims 1 to 5 , wherein the pigment is at least one of Blue1, 2, 3, 15, 15: 3, 1 :: 4, 16, 22, 60, 63, 66 A method for producing a dispersion. A pigment dispersion characterized by containing at least a pigment, water, polyoxyethylene having a polymerization degree of 30 to 120 , and a compound represented by the following general formula (1).

(In the formula, R represents an alkyl group having 1 to 20 carbon atoms, an aryl group, or an aralkyl group, l represents an integer of 0 to 7, and n represents an integer of 20 to 200.) The pigment dispersion according to claim 10 , wherein the compound represented by the general formula (1) is POE (n = 40) β-naphthyl ether. The pigment dispersion according to claim 10 or 11 , wherein the polyoxyethylene is contained in an amount of 0.1 to 10% by weight based on the compound represented by the general formula (1). The pigment dispersion according to any one of claims 10 to 12 , wherein the concentration of the pigment in the pigment dispersion is 5 to 50% by weight. The average particle size (D50) of the pigment particles in the pigment dispersion is 150 nm or less, and the particle size standard deviation in the particle size distribution of the pigment particles is smaller than the average particle size (D50). The pigment dispersion according to any one of claims 10 to 13 . The pigment dispersion according to any one of claims 10 to 14 , wherein the black pigment is carbon black among the pigments. Among the pigments, the yellow pigment is Pig. Yellow1, 2, 3, 12, 13, 14, 16, 17, 73, 74, 75, 83, 93, 95, 97, 98, 114, 120, 128, 129, 138, 150, 151, 154, 155, The pigment dispersion according to any one of claims 10 to 14 , wherein the pigment dispersion is at least one of 174 and 180. Among the pigments, magenta pigments are Pig. Red 5, 7, 12, 48 (Ca), 48 (Mn), 57 (Ca), 57: 1, 112, 122, 123, 146, 168, 176, 184, 185. 202, Pig. The pigment dispersion according to any one of claims 10 to 14 , wherein the pigment dispersion is at least one of Violet19. Among the pigments, the cyan pigment is Pig. The pigment dispersion according to any one of claims 10 to 14 , wherein the pigment dispersion is at least one of Blue 1, 2, 3, 15, 15: 3, 15: 4, 16, 22, 60, 63, and 66. liquid. The pigment dispersion according to any one of claims 10 to 18 , further comprising at least one additive selected from the group consisting of a water-soluble organic solvent, a surfactant, an antiseptic, and an antifungal agent. Ink jet ink. The ink-jet ink according to claim 19 , wherein the pigment concentration is 1 to 15% by weight. 21. An ink cartridge containing the ink-jet ink according to claim 19 or 20 . The ink cartridge according to claim 21 , wherein the ink cartridge is detachable from the image forming apparatus. 21. An image forming body, wherein an image is formed on a receptor using the ink jet ink according to claim 19 or 20 . The image forming body according to claim 23 , wherein the receiver is paper. 21. An image forming method comprising forming an image on a receptor using the ink jet ink according to claim 19 or 20 . 21. An image forming method, wherein the inkjet ink according to claim 19 or 20 is ejected from an image forming apparatus to the receptor. 27. The image forming method according to claim 26 , wherein the image forming apparatus is an ink jet printer. 28. The image forming method according to claim 27 , wherein the ink jet printer is a piezo ink jet printer. 28. The image forming method according to claim 27 , wherein the ink jet printer is a thermal ink jet printer.