JP2007099877A - Ink for inkjet recording, inkjet recording method, ink cartridge, and inkjet recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink for inkjet recording, capable of stably recording an image having high fastness and excellent appearance quality for a long period even in any case. <P>SOLUTION: The ink for the inkjet recording, at least containing a pigment dispersing element dispersed by a polymer dispersant, an assistant component and water is characterized by the assistant component composed of a block copolymer having at least one kind of a hydrophobic block and at least one kind of a hydrophilic block, and each block is constituted by polymerizing vinyl ethers. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ink for ink jet recording (hereinafter sometimes simply referred to as “ink”), an ink jet recording method, an ink cartridge, and an ink jet recording apparatus. More specifically, the present invention relates to a pigment dispersion type aqueous ink suitable for ink jet recording with high ejection reliability and good image characteristics, an ink jet recording method, an ink cartridge, and an ink jet recording apparatus using the ink.

  In recent years, pigment dispersion type water-based inks have been used for inkjet recording from the viewpoint of image fastness also in inkjet recording applications. In inkjet recording, in order to improve the fixability of ink on paper and the water resistance of printed images, it is an attempt to give the pigment dispersion (dispersed pigment particles) in the ink an aggregating function and a water insolubilizing function. Has been taken. However, by imparting such a function to the pigment dispersion, the dispersion stability of the pigment particles in the ink is lowered, and the pigment dispersion aggregates during storage of the ink, resulting in uneven density and sedimentation. There is a problem that nozzles are likely to be clogged due to ink drying at the nozzle tip portion of the ink jet apparatus, and ink ejection stability tends to be lowered. Also in printed images, the pigment dispersion tends to agglomerate on the surface of the recording material, resulting in a reduction in image scratch resistance, and further due to light scattering by the agglomerated pigment particles, the saturation of the image is greatly reduced and color development occurs. There is also a problem that the property deteriorates.

In order to solve the above problem, in Patent Document 1, in an ink in which water-insoluble polymer particles contain carbon black, the acid value and neutralization degree of the water-insoluble polymer and the pH of the carbon black have a predetermined composition. Although combined inks have been proposed, even though the inks have an effect on the scratch resistance and color developability of the printed matter, the ink ejection properties are not necessarily sufficient. Patent Document 2 proposes a colored microcapsule in which a pigment is coated with a resin and an ink that contains a resin that is not coated with a pigment and that is free and dissolved. However, when the ink composition changes greatly, as in the case of ink concentration at the nozzle tip, which is always generated when used in an ink jet apparatus, the dispersion stability of the pigment tends to be reduced. The discharge stability is not at a satisfactory level.
JP 2003-231831 A JP-A-10-292143

  An object of the present invention is made in view of the above problems, and is to provide an ink capable of stably recording an image having high fastness and excellent quality over a long period of time in any case. Furthermore, another object of the present invention is to provide an ink jet recording method capable of recording an image having excellent robustness and quality, and an ink cartridge and an ink jet recording apparatus including such an ink.

As a result of intensive studies to solve the above problems, the present inventors have found that the following problems can be solved by the present invention. That is, the present invention relates to an ink containing at least a pigment dispersion dispersed with a polymer dispersant, an auxiliary component, and water.
(A) The polymer dispersant has at least one hydrophobic block and at least one hydrophilic block, and each block is composed of a block copolymer obtained by polymerizing vinyl ethers. The polymer dispersant has an acid value in the range of 30 mg to 250 mg-KOH / g, and 10 to 50 mol% of the acid groups are unneutralized; and (b) the auxiliary component is at least An ink having one hydrophobic block and at least one hydrophilic block, wherein each block is composed of a block copolymer obtained by polymerizing vinyl ethers is provided.

  In the ink of the present invention, the auxiliary component has an acid value in the range of 0.1 to 0.5 times the acid value of the polymer dispersant, and 10 mol% to 50 mol of the acid group. % Is an unneutralized block copolymer; the auxiliary component is contained in a mass ratio of 0.1 to 3.0 times with respect to the polymer dispersant; It is preferable to contain a calcium and / or magnesium compound; and the neutralizing agent of at least one block copolymer of the polymer dispersant and the auxiliary component is a compound containing an alkali metal salt.

  Further, in the ink of the present invention, a hydrophilic block of at least one block copolymer of the polymer dispersant and the auxiliary component is composed of a vinyl ether having a nonionic hydrophilic group, At least one block copolymer composed of vinyl ethers having an anionic hydrophilic group; and at least one block copolymer of the polymer dispersant and the auxiliary component is composed of hydrophobic vinyl ethers. The block is preferably composed of at least a block composed of a vinyl ether having a nonionic hydrophilic group and a block composed of a vinyl ether having an anionic hydrophilic group.

  Further, the present invention provides an ink jet recording method in which energy is applied to the ink, the ink is ejected and applied to a recording material, and the ink is the ink of the present invention. I will provide a. In the inkjet recording method, the energy is preferably thermal energy; and the recording material is preferably a recording material having a coating layer that receives ink on at least one surface.

  According to another aspect of the present invention, there is provided an ink cartridge including an ink storage portion storing ink, wherein the ink is the ink of the present invention; and an ink cartridge including an ink storage portion storing ink And an ink jet recording apparatus having a head part for discharging the ink, wherein the ink is the ink of the present invention.

  According to the present invention, it is possible to provide an ink capable of stably recording an image having high fastness and excellent quality in any case over a long period of time, and further excellent in fastness and quality. An ink jet recording method, an ink cartridge, and an ink jet recording apparatus capable of recording an image can be provided.

Hereinafter, the present invention will be described in detail.
In the ink containing at least a pigment dispersion dispersed with a polymer dispersant, an auxiliary component, and water,
(A) The polymer dispersant has at least one hydrophobic block and at least one hydrophilic block, and each block is composed of a block copolymer obtained by polymerizing vinyl ethers. The polymer dispersant has an acid value in the range of 30 mg to 250 mg-KOH / g, and 10 to 50 mol% of the acid groups are unneutralized; and (b) the auxiliary component is at least The above object of the present invention is achieved by an ink having one type of hydrophobic block and at least one type of hydrophilic block, each block comprising a block copolymer obtained by polymerizing vinyl ethers. I found out.

  In the ink of the present invention, a polymer compound comprising a block copolymer including at least one hydrophobic block and at least one hydrophilic block is used as a pigment dispersant, thereby dispersing the polymer. The hydrophobic block portion of the agent adheres to the surface of the pigment particle, and the polymer dispersant can coat the pigment particle, that is, the pigment particle can be encapsulated. Further, since the hydrophilic part of the polymer dispersant is blocked, the affinity between the dispersant and the ink medium is improved, and the conventional polymer dispersant is randomly polymerized containing a hydrophobic group. In comparison with the above, since the dispersion stability of the pigment is improved, the aggregation and precipitation of the pigment particles are less likely to occur, and the stability of the ink during long-term storage is also considered to be good.

  Furthermore, when a block copolymer having an acid value in the range of 30 mg to 250 mg-KOH / g and 10 to 50 mol% of the acid groups is unneutralized is used as the polymer dispersant. A part of the hydrophilic part exists as an unneutralized acidic group. As a result, when the ink is ejected onto the paper surface, the hydrophilic portion is insolubilized in a short time compared to the case of using a polymer dispersant in which the hydrophilic portion of the polymer dispersant is completely neutralized. Therefore, it is considered that the time until the pigment is fixed on the paper surface is shortened. As described above, the polymer dispersant encapsulating the pigment particles is quickly fixed on the paper surface, so that the amount of the pigment remaining on the paper surface is increased, so that a high print density is considered to be developed.

  Furthermore, since the auxiliary component added to the ink is a block copolymer in which hydrophobic groups and hydrophilic groups are blocked, the hydrophobic group blocks face the inside in the ink medium to form a stable core, and the hydrophilic component becomes hydrophilic. A “micelle” in which the base block faces outward can be stably formed. Therefore, the affinity between the hydrophilic group of the auxiliary component and the hydrophilic group of the polymer dispersant forming the pigment dispersion works well, and the hydrophilic group of the auxiliary component is also good as the hydrophilic group of the recording material. Since the ink has an affinity, it is considered that when ink is printed on the surface of the recording material, the auxiliary component exerts an action of connecting the pigment dispersion and the recording material, thereby improving the image fixing property. In addition, it is considered that since the auxiliary component is present between the pigment particles, aggregation between the pigment particles is also suppressed, so that a decrease in color developability is also prevented.

  In addition, in the case of the present invention, as described above, the pigment particles can maintain sufficient hydrophilicity by further containing a block copolymer as an auxiliary component in the ink, thereby preventing deterioration of ink ejection properties. It is possible.

  With these effects, there is no decrease in image fixability and color development due to aggregation of the pigment dispersion on the surface of the recording material, which is a disadvantage of the pigment dispersion type ink, and the stability during long-term storage of the ink is improved. Even when the ink composition changes greatly, such as ink concentration at the nozzle tip, which always occurs when used in an inkjet device, stable dispersion of the ink is possible without lowering the dispersion stability of the pigment. Become.

Hereinafter, the constituent materials of the ink of the present invention will be described in detail.
(Polymer dispersant)
The polymer dispersant used in the ink of the present invention is a block copolymer having both a hydrophobic block composed of vinyl ethers and a block having hydrophilic groups composed of vinyl ethers, and Any acid copolymer having an acid value in the range of 30 mg to 250 mg-KOH / g and 10 to 50 mol% of the acid groups is an unneutralized block copolymer can be used. In this case, the polymer dispersant may be a block copolymer having at least one hydrophilic block and at least one hydrophobic block, each block made of a vinyl ether. Those having the above hydrophilic block or two or more types of hydrophobic blocks can be used, and a single block copolymer or a mixture of two or more types of block copolymers can also be used.

  A block copolymer in which the hydrophilic block of the polymer dispersant has at least a block composed of vinyl ethers having a nonionic hydrophilic group and a block composed of vinyl ethers having an anionic hydrophilic group Preferably, a block composed of a hydrophobic vinyl ether, a block composed of a hydrophilic vinyl ether having a nonionic hydrophilic group, and a block composed of a hydrophilic vinyl ether having an anionic hydrophilic group It is preferable that it is comprised at least. Examples of the form of the copolymer include a linear type and a graft type, and a linear type block copolymer is preferable.

The block copolymer used in the present invention preferably has a repeating unit structure represented by the following general formula (1), for example.
^{_{- (CH 2 -CH (OR 1}} )) - (1)
As the block having a hydrophobic group, in the general formula (1), R ¹ is an aliphatic hydrocarbon such as an alkyl group, an alkenyl group, a cycloalkyl group, or a cycloalkenyl group, a phenyl group, a pyridyl group, a benzyl group. Represents an aromatic hydrocarbon group in which the carbon atom may be substituted with a nitrogen atom, such as a group, toluyl group, xylyl group, alkylphenyl group, phenylalkylene group, biphenyl group, and phenylpyridyl group. Moreover, the hydrogen atom on said aromatic ring may be substituted by the hydrocarbon group. R ¹ preferably has 1 to 18 carbon atoms.

Further, R ¹ may be represented by — (CH ₂ ) _m — (O) _n —R ⁴ . R ⁴ represents an aliphatic hydrocarbon such as an alkyl group, alkenyl group, cycloalkyl group, or cycloalkenyl group, phenyl group, pyridyl group, benzyl group, toluyl group, xylyl group, alkylphenyl group, phenylalkylene group. An aromatic hydrocarbon group in which the carbon atom may be substituted with a nitrogen atom, such as a biphenyl group or a phenylpyridyl group (the hydrogen atom on the aromatic ring may be substituted with a hydrocarbon group), _{-CHO, -CH 2 CHO, -CO-} CH = CH 2, -CO-C (CH 3) = CH 2, -CH 2 -CH = CH 2, -CH 2 -C (CH 3) = CH 2, —CH ₂ —COOR ⁵ or the like, and a hydrogen atom in these groups may be substituted with a halogen atom such as fluorine, chlorine, or bromine as long as it is chemically possible. The number of carbon atoms of R ⁴ is 1 to 18 is preferred. m is preferably from 3 to 36, and n is preferably 0 or 1. In the above, R ⁵ is the same as R ⁴ .

As a block composed of vinyl ethers having a nonionic hydrophilic group composed of an oxyethylene group, in the above formula (1), R ¹ is — (CH (R ² ) —CH (R ³ ) —O). it is represented by _p -R ^4. In this case, R ² and R ³ each independently represents a hydrogen atom or a methyl group, and R ⁴ is an aliphatic hydrocarbon such as an alkyl group, an alkenyl group, a cycloalkyl group, or a cycloalkenyl group, as described above. Aromatic carbonization in which carbon atoms may be substituted with nitrogen atoms, such as phenyl group, pyridyl group, benzyl group, toluyl group, xylyl group, alkylphenyl group, phenylalkylene group, biphenyl group, phenylpyridyl group A hydrogen group (the hydrogen atom on the aromatic ring may be substituted with a hydrocarbon group), —CHO, —CH ₂ CHO, —CO—CH═CH ₂ , —CO—C (CH ₃ ) ═CH _{2 , -CH 2 -CH = CH 2,} -CH 2 -C (CH 3) = CH 2, represent like -CH ₂ -COOR ^5, hydrogen atoms of these groups are chemically range , Fluorine, chlorine, may be substituted with a halogen atom such as bromine. The number of carbon atoms of R ⁴ is 1 to 18 is preferred. p is preferably 1-18. In the above, R ⁵ is the same as R ⁴ .

Examples of the alkyl group or alkenyl group in R ¹ and R ⁴ in the above formula include methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, t-butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl. , Dodecyl, tetradecyl, hexadecyl, octadecyl, oleyl, linoleyl, and the like. Examples of the cycloalkyl group or cycloalkenyl group include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cyclooctyl, and cyclohexenyl.

The block is composed of a vinyl ether having an anionic hydrophilic group, R ¹ in the formula (1) _{is, -CH 2 CH 2 CH 2 OCH} 2 COOH, -CH 2 CH 2 COOH, -CH 2 COOH, And — (CH (R ² ) —CH (R ³ ) —O) _p —R ⁵ —COOH and the like, and R ² and R ³ each independently represent a hydrogen atom or a methyl group, and R ⁵ Represents a methylene group, an ethylene group or a phenylene group. p is preferably 1-18.

  The structures of the vinyl ether monomers (Ia to Io) and the block copolymers (II-a to II-e) constituting the block copolymer used in the present invention are exemplified below. The polyvinyl ether structure of the block copolymer used is not limited to these.

Furthermore, it is preferable that the number of repeating units of the polyvinyl ether (in the above (II-a) to (II-e), m, n, l) is independently 1 to 10,000. Moreover, it is more preferable that the sum total is (m + n + 1 in the above (II-a) to (II-e)), 10 to 20,000. The number average molecular weight is preferably 500 to 20,000,000, more preferably 1,000 to 5,000,000, and most preferably 2,000 to 2,000,000.
The acid value of the polymer dispersant used in the present invention is in the range of 30 mg to 250 mg-KOH / g, but if it is in the range of 100 mg to 250 mg-KOH / g, the scratch resistance and color developability of the printed image are obtained. Most preferable in terms. Further, the unneutralized acid groups of these polymer dispersants are 10 to 50 mol%, and 10 to 30 mol% is most preferable in terms of ink ejection properties and print image fixing properties.

  The proportion of these polymer dispersants in the ink is preferably 0.1 to 20% by mass, more preferably 0.5 to 10% by mass, based on the total mass of the ink.

  A method for synthesizing a copolymer having a vinyl ether polymer block (block copolymer) is not particularly limited, but cation living polymerization by Aoshima et al. (JP-A Nos. 11-322942 and 11-322866) and the like can be used. Preferably used. By using the cationic living polymerization method, homopolymers with a uniform length (molecular weight), copolymers of two or more monomers, block copolymers, graft copolymers, gradation copolymers, etc. Various polymers can be synthesized. In addition, various functional groups can be introduced into the side chain of polyvinyl ether.

  The neutralizing agent for the anionic hydrophilic group of the polymer dispersant can neutralize the anionic hydrophilic group of the block copolymer as long as it is soluble in water. Can be used. Examples of such a neutralizing agent include compounds containing alkali metals such as lithium, sodium and potassium, amines such as monoethanolamine and triethanolamine, ammonia, etc., but compounds containing alkali metals It is more preferable because the color developability of the obtained image is further improved. Examples of the compound containing alkali metals include sodium, potassium, and lithium compounds, and compounds containing these alkali metals that are soluble in water are preferable. Specifically, alkali metal hydroxides such as sodium hydroxide, potassium hydroxide and lithium hydroxide, oxides such as sodium oxide, potassium oxide and lithium oxide, alkalis such as sodium carbonate, potassium carbonate and lithium carbonate Examples thereof include metal carbonates.

(Auxiliary ingredient)
The auxiliary component used in the ink of the present invention is a block copolymer comprising a hydrophobic block composed of at least one vinyl ether and a hydrophilic block composed of one or more vinyl ethers. Good. In particular, when the hydrophilic block of the block copolymer is composed of vinyl ethers having at least one anionic hydrophilic group, the affinity with the anionic hydrophilic group of the polymer dispersant constituting the pigment dispersion This is desirable because the property is improved. Among these, the auxiliary component hydrophilic block is composed of a vinyl ether having at least one nonionic hydrophilic group, and a block composed of a vinyl ether having at least one anionic hydrophilic group. Preferably, the auxiliary component includes a block composed of a hydrophobic vinyl ether, a block composed of a hydrophilic vinyl ether having a nonionic hydrophilic group, and a hydrophilic vinyl ether having an anionic hydrophilic group Is preferably at least in the order of the blocks constituted from the above because the affinity with the anionic hydrophilic group of the polymer dispersant is further improved and the affinity with the recording material is further improved. Specific examples of the block copolymer used as the auxiliary component used in the present invention include those having the same structure as that shown in the specific example of the block copolymer used as the polymer dispersant.

  In the present invention, the acid value of the auxiliary component is preferably in the range of 10 mg to 100 mg-KOH / g. Furthermore, the acid value of the block copolymer used as an auxiliary component is preferably 0.05 to 1.0 times, more preferably 0.1 to 0.5 times the acid value of the polymer dispersant. It is. When the acid value is less than 0.05 times the acid value of the polymer dispersant, the scratch resistance and color developability of the printed image may be slightly reduced. Dispersion stability and ejection stability may be reduced. Moreover, it is preferable that 10-50 mol% of the acid group of the auxiliary component is not neutralized. If the acid group non-neutralization degree is less than 10 mol% (that is, the acid group neutralization degree is 90 mol% or more), the scratch resistance and color developability of the printed image may be deteriorated. When the sum exceeds 50 mol% (that is, the neutralization degree of the acid group is 50 mol% or less), the dispersion stability and ejection stability of the ink may decrease. Furthermore, it is preferable that the addition amount of the auxiliary component is contained in a range of 0.03 times to 4.0 times by mass ratio with respect to the polymer dispersant, It is more preferable that it is contained in a range. When the ratio is smaller than 0.03 times, the affinity with the hydrophilic group of the block copolymer of the polymer dispersant forming the pigment dispersion is insufficient, and the fixability of the printed matter may be deteriorated. When the ratio is larger than 0 times, it takes a long time until the auxiliary component is fixed on the paper surface, so that the water resistance immediately after printing tends to be poor.

  Moreover, as an anionic hydrophilic group neutralizing agent of the block copolymer as an auxiliary component, any neutralizing agent capable of neutralizing the anionic hydrophilic group of the block copolymer can be used. As such a neutralizing agent, the same compound as the neutralizing agent used for the polymer dispersant can be used, but it is obtained when the compound contains an alkali metal such as potassium or sodium. This is preferable because the color developability of the image is further improved.

(Pigment dispersion)
The pigment dispersion used in the ink of the present invention is a pigment dispersion in which a pigment is dispersed by the polymer dispersant. As a method for producing a pigment dispersion in the present invention, for example, a pigment and a polymer dispersant are kneaded and added and dispersed in a predetermined liquid medium, and then water for dilution and various additives are added. The method of manufacturing by this is mentioned. A kneader or a roll mill can be used for kneading, and a dispersing machine such as ultrasonic wave application, bead mill, or ball mill can be used for dispersion. Neutralization of the anionic hydrophilic group in the polymer dispersant by addition of alkali may be performed before or after mixing the pigment and the polymer dispersant, but is preferably performed after mixing.

(Pigment)
Examples of the pigment constituting the pigment dispersion are shown below, but are not limited thereto.
Raven 760 Ultra, Raven 1060 Ultra, Raven 1080, Raven 1100 Ultra, Raven 1170, Raven 1200, Raven 1250, Raven 1255, Raven 1500, Raven 2000, Raven 2500 Ultra, Raven 3500, Raven 5250, Raven 5750, Raven 7000, Raven 5000 ULTRAII, Raven 1190 ULTRAII (above Colombian Carbon); Black Pearls L, MOGUL-L, Regal400R, Regal660R, Regal330R, Monarch 800, Monarch 880, Monarch 900, Monarch 1000, Monarch 1300, Monarch 1400 (above Color Black FW1, Color Black FW2, Color Black FW200, Color Black 18, Color Black S160, Color Black S170, Special Black 4, Special Black 4A, Special Black 6, Special Black 550, Printex 35, Printex 45, Printex 55, Printex 85, Printex 95, Printex U, Printex 140U, Printex V, Printex 140V (above, manufactured by Degussa);

No. 25, no. 33, no. 40, no. 45, no. 47, no. 52, no. 900, no. 970, no. 2200B, no. 2300, no. 2400B, MCF-88, MA600, MA77, MA8, MA100, MA230, MA220 (above, manufactured by Mitsubishi Chemical Corporation);

C. I. Pigment Yellow 3, 12, 13, 14, 17, 20, 24, 74, 83, 86, 93, 95, 97, 109, 110, 117, 120, 125, 128, 137, 138, 147, 148, 150, 151, 153, 154, 166, 168, 175, 180, 183, 184, 185; I. Pigment orange 16, 36, 43, 51, 55, 59, 61, 71; C.I. I. Pigment Red 9, 12, 48, 49, 52, 53, 57, 97, 122, 123, 149, 168, 175, 176, 177, 180, 184, 192, 202, 215, 216, 217, 220, 223, 224, 226, 227, 228, 238, 240, 254, 255, 272; I. Pigment violet 19, 23, 29, 30, 32, 37, 40, 50; C.I. I. Pigment Blue 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 16, 22, 60, 64; C.I. I. Pigment green 7, 36; I. Pigment brown 23, 25, 26; I. Pigment Black 1, 10, 31, 32, etc.

  The content of these pigments is preferably in the range of 0.1 to 20% by mass, more preferably 1.0 to 10% by mass with respect to the total mass of the ink. If the amount of the pigment is less than 0.1% by mass, it may be difficult to obtain a sufficient image density. If the amount exceeds 20% by mass, the ejection stability is likely to deteriorate due to clogging of the nozzle. Further, the content ratio of the pigment and the polymer dispersant in the ink is preferably from 100: 1 to 1: 2 in terms of solid content mass from the viewpoint of ink ejection stability and storage stability. These pigments can be used in combination of two or more, in addition to being used alone.

  The above are the essential components of the ink of the present invention. In addition to these components, it is preferable to add a nonionic surfactant. Nonionic surfactants preferably used in the ink of the present invention are compounds having a nonionic hydrophilic group and a hydrophobic group typified by an oxyethylene group and containing no anionic or cationic ionic group. , HLB is preferably in the range of 11.0 to 18.5. When the HLB is less than 11.0, the effect on the dispersion stability of the pigment dispersion in the ink is weak, and when the HLB is higher than 18.5, the water resistance of the image may be lowered. As such a thing, Preferably, at least 1 type chosen from polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene alkyl allyl ether is mentioned. Further specific examples include polyoxyethylene octyl ether, polyoxyethylene nonyl ether, polyoxyethylene dodecyl ether, polyoxyethylene lauryl ether, polyoxyethylene oleyl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene Nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl phenyl ether and the like can be mentioned. Further, polyoxyalkylene alkyl ether, polyoxyethylene polyoxypropylene alkyl ether, polyoxyethylene-oxypropylene block polymer and the like may be used.

  The content of the nonionic surfactant in the ink of the present invention is preferably 0.01 to 10% by mass and more preferably 0.1 to 5% by mass with respect to the total mass of the ink. If the amount of the nonionic surfactant is less than 0.01% by mass, the effect of adding the surfactant cannot be obtained. If the amount exceeds 5% by mass, the ink penetration effect on the recording medium is increased and the image density is lowered. However, the print quality may deteriorate. Further, it is desirable from the viewpoint of ink ejection stability and dispersion stability that the nonionic surfactant is contained in a mass ratio of 0.02 to 2.0 times that of the pigment dispersion. In addition, when the nonionic surfactant is contained in a mass ratio of 0.5 to 3.0 times the mass of the block copolymer (dispersant), ink ejection stability and ink dispersion stability are achieved. Desirable from the viewpoint of sex.

  In addition, it is preferable to include calcium ions and / or magnesium ions in the ink because the long-term storage stability of the ink and the ink ejection stability are improved. This is because the interaction between the hydrophilic blocks is improved by a bridging effect in which calcium ions or magnesium ions having a divalent positive charge act on the ether group having a negative charge of the hydrophilic block of the polymer dispersant, The outer shape of the pigment dispersion capsule formed by the hydrophilic block portion is stabilized. For this reason, even when the capsule shape tends to become unstable, such as when the ink is heated, the entire capsule is maintained in a uniform shape, so that the capsule surface charge state is hardly generated and the capsule surface is hardly disturbed. This is presumably because the agglomeration of capsules and aggregation due to electrostatic factors are greatly reduced.

  As the content of such calcium ions and magnesium ions in the ink, the total amount of calcium ions and magnesium ions is preferably in the range of 1: 100,000 to 1: 100 by mass ratio with respect to the polymer dispersant. The range of 1: 50,000 to 1: 200 is preferable because the storage stability is further improved. When the content of calcium ions and magnesium ions is less than 1: 100,000, the effect of improving the storage stability of the ink may be reduced, and when the content is more than 1: 100, clogging of the nozzles is likely to occur. . Specific examples of calcium compounds and magnesium compounds that are preferably added to the ink include calcium chloride, magnesium chloride, calcium nitrate, magnesium nitrate, calcium sulfate, magnesium sulfate, calcium hydroxide, magnesium hydroxide, calcium oxide, and magnesium oxide. Etc. In addition to the above components, various additives such as a water-soluble organic solvent, a surfactant, a pH adjuster, an antioxidant, and an antifungal agent may be added and used.

  As the water-soluble organic solvent used in the ink of the present invention, any water-soluble organic solvent can be used, and it can be used as a mixed solvent of two or more water-soluble organic solvents.

  Specific examples of preferred water-soluble organic solvents include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol and other lower alcohols; ethylene glycol, diethylene glycol, Triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, thiodiglycol, 1,4-cyclohexanediol Diols such as: Triols such as glycerin, 1,2,4-butanetriol, 1,2,6-hexanetriol, 1,2,5-pentanetriol; trimethylolpro Hindered alcohols such as ethylene, trimethylolethane, neopentyl glycol, pentaerythritol; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monoallyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether , Glycol ethers such as diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether; dimethyl sulfoxide, glycerin monoallyl ether, polyethylene glycol, N- Methyl-2- Loridone, 2-pyrrolidone, γ-butyrolactone, 1,3-dimethyl-2-imidazolidinone, sulfolane, β-dihydroxyethylurea, urea, acetonylacetone, dimethylformamide, dimethylacetamide, acetone, diacetone alcohol, tetrahydrofuran, And dioxane.

  Among these, it is preferable to use a water-soluble organic solvent having a boiling point of 120 ° C. or more because ink concentration at the nozzle tip is suppressed. The proportion of these water-soluble organic solvents in the ink is preferably 5 to 50% by mass and more preferably 10 to 30% by mass with respect to the total mass of the ink.

  A feature of the ink jet recording method of the present invention is that the ink of the present invention is used in an ink jet recording method performed by applying energy to the ink and causing the ink to fly. As the energy, thermal energy or mechanical energy can be used, but it is preferable to use thermal energy.

  In the ink jet recording method of the present invention, the recording material is not limited, but ink is received on at least one surface such as so-called ink jet exclusive paper, postcards and business card paper, label paper, cardboard paper, and ink jet film. A recording material having a coating layer is preferably used. As the recording material having a coating layer, a recording material having a coating layer for receiving ink on at least one surface containing at least a hydrophilic polymer and / or an inorganic porous material is desirable.

  Examples of the ink jet recording apparatus that performs recording using the ink of the present invention include a general household printer mainly used for A4 size paper, a printer for printing business cards and cards, and a large business printer. However, an example of a suitable inkjet recording apparatus will be described below.

(Inkjet recording device using thermal energy)
FIG. 1 is a diagram illustrating an example of an ink cartridge 100 that stores ink supplied to a head via an ink supply tube 104. Reference numeral 101 denotes an ink bag containing ink for supply, and a stopper 102 made of chlorinated butyl rubber is provided at the tip thereof. By inserting the needle 103 into the stopper 102, the ink in the ink bag 101 can be supplied to the recording heads (303 to 306). An ink absorber that receives waste ink may be provided in the ink cartridge. The ink jet recording apparatus used in the present invention is not limited to the one in which the recording head and the ink cartridge are separated as described above, and an apparatus in which they are integrated is also preferably used.

  FIG. 2 is a schematic diagram for explaining the structure of the ink jet recording head used in this embodiment. Each nozzle 202 is provided with a corresponding heating element 204 (heater), which is heated by applying a predetermined driving pulse from the recording head driving circuit to the heater 204 to generate air bubbles. Ink droplets are discharged from the discharge port 202. The heater 204 is formed on the silicon substrate 206 by the same method as in the semiconductor manufacturing process. Reference numeral 203 denotes a nozzle partition that constitutes each nozzle 202, 205 denotes a common liquid chamber for supplying ink to each nozzle 202, and 207 denotes a top plate.

  A partial perspective view of the recording apparatus according to the present embodiment is shown in FIG. The recording paper 302 of the recording apparatus 300 is supplied from, for example, a roll supply unit 301 and is continuously conveyed by a conveyance unit provided in the main body of the recording apparatus 300. The transport unit includes a transport motor 312 and a transport belt 313. For recording, when the image cutout position of the recording medium passes under the black recording head 303, the black ink starts to be ejected from the recording head. Similarly, the ink of each color is selected in the order of cyan 304, magenta 305, and yellow 306. The color image is formed.

  In addition, the recording apparatus 300 includes a cap mechanism 311 that caps each recording head during standby, ink cartridges 307 to 310 for supplying ink to the recording heads 303 to 306, and a pump for supplying and recovering ink. A unit (not shown), a control board (not shown) for controlling the entire recording apparatus, and the like are included.

  FIG. 4 is a schematic diagram of a recovery processing system in the ink jet recording apparatus used in this embodiment. When the recording heads 303 to 306 are lowered, a predetermined recovery operation can be performed when the ink discharge port forming surface comes close to the cap 400 formed of chlorinated butyl rubber in the cap mechanism 311.

  In the recovery processing system, the ink regeneration circuit unit stores between the ink cartridge 100 in which replenished ink is stored and accommodated in a polyethylene bag, a sub tank 401 connected via a suction pump 403, and the like, and between the cap 400 and the sub tank 401. A suction pump 403 that is disposed in an ink supply path 409 formed of vinyl chloride to be connected and collects ink from the cap mechanism 311 in the sub tank 401, a filter 405 that removes dust and the like in the ink collected from the cap, and an ink supply path 408 The main components are a pressurizing pump 402 that supplies ink to the common liquid chambers of the recording heads 303 to 306, an ink supply path 407 that supplies ink returned from the recording head to the sub tank 401, and valves 404a to 404d. It is configured.

  When the recording heads 303 to 306 are cleaned, the recovery valve 404b is closed and the pressurizing pump 402 is operated to pressurize and supply ink from the sub tank 401 to the recording head and forcibly discharge the ink from the nozzle 406. As a result, bubbles, ink, dust and the like in the nozzles of the recording head are discharged. The suction pump 403 collects the ink discharged from the recording head into the cap mechanism 311 in the sub tank 401.

(Inkjet recording device using mechanical energy)
Next, as a preferable example of an ink jet recording apparatus using mechanical energy, a nozzle forming substrate having a plurality of nozzles, a pressure generating element made of a piezoelectric material and a conductive material disposed opposite to the nozzles, and the pressure An on-demand ink jet recording head that includes ink that fills the periphery of the generating element, displaces the pressure generating element by an applied voltage, and discharges a small droplet of ink from a nozzle can be exemplified. FIG. 5 shows an example of the configuration of a recording head that is a main part of the recording apparatus.

  The head includes an ink flow path 80 communicating with an ink chamber (not shown), an orifice plate 81 for ejecting ink droplets of a desired volume, a vibration plate 82 that directly applies pressure to ink, and the vibration plate 82. And a substrate 84 for indicating and fixing the orifice plate 81, the vibration plate 82, and the like.

  In FIG. 5, an ink flow path 80 is formed of a photosensitive resin or the like, an orifice plate 81 is formed with a discharge port 85 by drilling a metal such as stainless steel or nickel by electroforming or pressing, and the diaphragm 82 is The piezoelectric element 83 is formed of a dielectric material such as barium titanate or PZT. The piezoelectric element 83 is formed of a metal film such as stainless steel, nickel, or titanium and a highly elastic resin film. The recording head configured as described above applies a pulsed voltage to the piezoelectric element 83 to generate strain stress, and the energy deforms the vibration plate 82 bonded to the piezoelectric element 83, so that the inside of the ink flow path 80. An operation is performed so as to perform recording by pressurizing the ink vertically and ejecting ink droplets (not shown) from the ejection port 85 of the orifice plate 81.

  Hereinafter, the present invention will be described in detail based on examples and comparative examples. The present invention is not limited to these examples. In the text, “parts” and “%” are based on mass unless otherwise specified.

(Preparation of block copolymer A)
<Synthesis of AB type block copolymer comprising hydrophobic block and hydrophilic block>:
After the inside of the glass container fitted with the three-way cock was replaced with nitrogen, the adsorbed water was removed by heating at 250 ° C. in a nitrogen gas atmosphere. After returning the system to room temperature, 6 mmol of 2-phenoxyethyl vinyl ether, 16 mmol of ethyl acetate, 0.1 mmol of 1-isobutoxyethyl acetate, and 11 cm ³ of toluene were added, and when the system temperature reached 0 ° C., ethyl was added. Polymerization was started by adding 0.2 mmol of aluminum sesquichloride, and the A component of the AB type block copolymer was synthesized.

The molecular weight is monitored in a time-sharing manner using molecular sieve column chromatography (GPC), and after the polymerization of component A is completed, the carboxylic acid part of 4- (2-vinyloxyethoxy) benzoic acid (component B) is ethylated. The synthesis was carried out by adding 50 mmol of vinyl monomer esterified with a group. The polymerization reaction was stopped by adding a 0.3% ammonia / methanol solution to the system, and the esterified carboxyl group was hydrolyzed with a sodium hydroxide / methanol solution to change to a carboxylic acid type. Diluted by adding dichloromethane to the mixed solution after the reaction, washed 3 times with 0.6N hydrochloric acid solution, then 3 times with distilled water, concentrated and dried with an evaporator, and vacuum-dried to block copolymer A was obtained. The compound was identified using NMR and GPC (Mn = 3.9 × 10 ⁴ , Mw / Mn = 1.2). The acid value of the obtained block copolymer was 240 mg-KOH / g.

(Preparation of block copolymer B)
<Synthesis of ABC type block copolymer composed of hydrophobic block and two hydrophilic blocks>:
After the inside of the glass container fitted with the three-way cock was replaced with nitrogen, the adsorbed water was removed by heating at 250 ° C. in a nitrogen gas atmosphere. After returning the system to room temperature, 30 mmol of n-octadecyl vinyl ether, 16 mmol of ethyl acetate, 0.1 mmol of 1-isobutoxyethyl acetate, and 11 cm ³ of toluene were added, and when the internal temperature reached 0 ° C., ethyl aluminum Polymerization was started by adding 0.2 mmol of sesquichloride, and the A component of the ABC type block copolymer was synthesized.

The molecular weight was monitored in a time-sharing manner using molecular sieve column chromatography (GPC), and after the polymerization of component A was completed, 2- (2- (2- (2-methoxyethoxy) ethoxy) ethoxy) ethoxyvinyl ether ( Polymerization was continued by adding 40 mmol of component B). Similarly, the molecular weight was monitored by GPC, and after the polymerization of the B component was completed, 4 mmol of vinyl monomer obtained by esterifying the carboxylic acid part of 6- (2-vinyloxyethoxy) hexanoic acid (C component) with an ethyl group The synthesis was performed by adding The polymerization reaction was stopped by adding a 0.3% ammonia / methanol solution to the system, and the esterified carboxyl group was hydrolyzed with a sodium hydroxide / methanol solution to change to a carboxylic acid type. Thereafter, the block copolymer B was obtained in the same manner as the block copolymer A. The compound was identified using NMR and GPC (Mn = 3.8 × 10 ⁴ , Mw / Mn = 1.3). The acid value of the obtained block copolymer was 11.8 mg-KOH / g.

(Preparation of block copolymer C)
To the block copolymer B, n-octadecyl vinyl ether (component A) is 15 mmol, 2- (2- (2- (2-methoxyethoxy) ethoxy) ethoxy) ethoxyvinyl ether (component B) is 20 mmol, 6 Blocking was carried out in the same manner as in the case of the block copolymer B except that the vinyl monomer obtained by esterifying the carboxylic acid part of the (2-vinyloxyethoxy) hexanoic acid (C component) with an ethyl group was changed to 15 mmol. Copolymer C was obtained. The compound was identified using NMR and GPC (Mn = 3.1 × 10 ⁴ , Mw / Mn = 1.3). The acid value of the obtained block copolymer was 69.1 mg-KOH / g.

(Preparation of block copolymer D)
The block copolymer B has n-octadecyl vinyl ether (component A) to 20 mmol, 2- (2- (2- (2-methoxyethoxy) ethoxy) ethoxy) ethoxyvinyl ether (component B) to 20 mmol, 6 Blocking was carried out in the same manner as in the case of the block copolymer B, except that the vinyl monomer obtained by esterifying the carboxylic acid portion of (2-vinyloxyethoxy) hexanoic acid (component C) with an ethyl group was changed to 10 mmol. Copolymer D was obtained. The compound was identified using NMR and GPC (Mn = 3.9 × 10 ⁴ , Mw / Mn = 1.3). The acid value of the obtained block copolymer was 44.4 mg-KOH / g.

(Preparation of block copolymer E)
<Synthesis of AB type block copolymer comprising hydrophobic block and hydrophilic block>:
After the inside of the glass container fitted with the three-way cock was replaced with nitrogen, the adsorbed water was removed by heating at 250 ° C. in a nitrogen gas atmosphere. After returning the system to room temperature, 8 mmol of biphenyl vinyl ether, 16 mmol of ethyl acetate, 0.1 mmol of 1-isobutoxyethyl acetate, and 11 cm ³ of toluene were added, and when the internal temperature reached 0 ° C., ethylaluminum sesquichloride was added. Polymerization was started by adding 0.2 mmol, and the A component of the AB type block copolymer was synthesized.

The molecular weight was monitored in a time-sharing manner using molecular sieve column chromatography (GPC), and after the polymerization of component A was completed, the carboxylic acid part of 6- (2-vinyloxyethoxy) benzoic acid (component B) was ethylated. The synthesis was carried out by adding 5 mmoles of vinyl monomers esterified with groups. The polymerization reaction was stopped by adding a 0.3% ammonia / methanol solution to the system, and the esterified carboxyl group was hydrolyzed with a sodium hydroxide / methanol solution to change to a carboxylic acid type. Diluted by adding dichloromethane to the mixed solution after the reaction, washed 3 times with 0.6N hydrochloric acid solution, then 3 times with distilled water, concentrated and dried with an evaporator, and vacuum-dried to block copolymer E was obtained. The compound was identified using NMR and GPC (Mn = 3.9 × 10 ⁴ , Mw / Mn = 1.2). The acid value of the obtained block copolymer was 105 mg-KOH / g.

(Preparation of block copolymer F)
Vinyl monomer in which 2-phenoxyethyl vinyl ether (component A) of block copolymer A is esterified to 20 mmol and the carboxylic acid part of 4- (2-vinyloxyethoxy) benzoic acid (component B) is esterified with an ethyl group The block copolymer F was obtained in the same manner as in the case of the block copolymer A, except that was changed to 9 mmol. The compound was identified using NMR and GPC (Mn = 3.1 × 10 ⁴ , Mw / Mn = 1.3). The acid value of the obtained block copolymer was 98 mg-KOH / g.

(Preparation of block copolymer G)
Vinyl monomer obtained by esterifying 2-phenoxyethyl vinyl ether (component A) of block copolymer A to 4 mmole and carboxylic acid part of 4- (2-vinyloxyethoxy) benzoic acid (component B) with ethyl group The block copolymer G was obtained in the same manner as in the case of the block copolymer A except that was changed to 85 mmol. The compound was identified using NMR and GPC (Mn = 5.0 × 10 ⁴ , Mw / Mn = 1.3). The acid value of the obtained block copolymer was 260 mg-KOH / g.

(Preparation of block copolymer H)
N-octadecyl vinyl ether (component A) of the block copolymer B is 20 mmol, 2- (2- (2- (2-methoxyethoxy) ethoxy) ethoxy) ethoxyvinyl ether (component B) is 30 mmol, Blocking was carried out in the same manner as in the case of the block copolymer B except that the vinyl monomer obtained by esterifying the carboxylic acid part of the (2-vinyloxyethoxy) hexanoic acid (component C) with an ethyl group was changed to 5 mmol. Copolymer H was obtained. The compound was identified using NMR and GPC (Mn = 5.0 × 10 ⁴ , Mw / Mn = 1.3). The acid value of the obtained block copolymer was 20 mg-KOH / g.

(Preparation of random copolymer I)
A glass four-necked flask equipped with a reflux tube, a dropping funnel, a thermometer, and a stirrer was charged with 300 parts of methyl ethyl ketone, and heated while stirring until reflux was constantly emitted from the reflux tube. The internal temperature at this time was 84 ° C. To this solution, a mixed solution of 130 parts of methacrylic acid, 300 parts of styrene and 24 parts of a polymerization initiator (ABN-E manufactured by Wako Pure Chemical Industries, Ltd.) was dropped at a constant rate over 180 minutes. After aging for another 30 minutes, a mixed solution of 100 parts of methyl ethyl ketone and 2 parts of ABN-E was added dropwise at a constant rate over 120 minutes. After completion of the dropping, the internal temperature was maintained for 60 minutes, followed by cooling, and 100 parts of methyl ethyl ketone was added to prepare a copolymer I. The obtained copolymer I had a weight average molecular weight of 15,000 and a structure in which each monomer was polymerized randomly.

When the acid values of the obtained copolymers A to I were measured, the results shown in Table 1 below were obtained. The acid value was measured by the method described in JIS-K0070.

[Example 1]
(Preparation of pigment dispersion I)
As a polymer dispersant, a methyl ethyl ketone solution of the block copolymer A and a commercially available pigment such as C.I. I. Pigment Blue 15: 3 was charged into a kneader having a twin screw and kneaded until uniform, and then the solvent was distilled off under reduced pressure while maintaining the internal temperature at 80 ° C. This kneaded product is made into a sheet using two rolls, a predetermined amount of ion-exchanged water and triethanolamine are used as a neutralizing agent, an amount corresponding to a neutralization degree of 50 mol% is added and stirred, a pigment concentration of 10%, high A pigment dispersion I having a molecular dispersant concentration of 3.0% was obtained.

(Preparation of ink 1)
-Pigment dispersion I 35.0 parts-6.0 parts of glycerin-6.0 parts of diethylene glycol-6.0 parts of trimethylolpropane-4.2 parts of neutralized triethanolamine of block copolymer B (degree of neutralization) 100 mol%)
-Ion-exchanged water 42.8 parts The above components were mixed and sufficiently stirred, and then filtered through a microfilter having a pore size of 3 µm to obtain the desired ink. The obtained ink was centrifuged and the separated supernatant was analyzed. As a result, 4.18% of the block copolymer B was contained in the ink.

[Example 2]
(Preparation of Pigment Dispersion II)
As a polymer dispersant, a methyl ethyl ketone solution of the block copolymer A and a commercially available pigment such as C.I. I. Pigment Red 122 was charged into a kneader having a twin screw and kneaded until uniform, and then the solvent was distilled off under reduced pressure while maintaining the internal temperature at 80 ° C. This kneaded product is made into a sheet using two rolls, a predetermined amount of ion-exchanged water and lithium hydroxide as a neutralizing agent are added, an amount corresponding to a neutralization degree of 60 mol% is added, and the mixture is stirred. A pigment dispersion II having a molecular dispersant concentration of 10% was obtained.

(Preparation of ink 2)
-Pigment Dispersion II 30.0 parts-Glycerol 6.0 parts-Diethylene glycol 6.0 parts-Trimethylolpropane 6.0 parts-Ammonia neutralized product of block copolymer A 0.15 parts (neutralization degree 85 mol%) )
-Ion-exchanged water 51.85 parts The above components were mixed and sufficiently stirred, and then filtered through a microfilter having a pore size of 3 µm to obtain the intended ink.

[Example 3]
(Preparation of Pigment Dispersion III)
As a polymer dispersant, a methyl ethyl ketone solution of the above block copolymer C and a commercially available pigment, carbon black (MA100, manufactured by Mitsubishi Chemical Corporation) were charged into a kneader having a biaxial screw, kneaded until uniform, and the internal temperature was reduced. While maintaining the temperature at 80 ° C., the solvent was distilled off under reduced pressure. This kneaded product is made into a sheet using two rolls, a predetermined amount of ion-exchanged water and ammonia as a neutralizing agent, an amount corresponding to a neutralization degree of 90 mol% is added and stirred, and the pigment concentration is 8%, the polymer A pigment dispersion III having a dispersant concentration of 6% was obtained.

(Preparation of ink 3)
Pigment dispersion III 50.0 parts Glycerol 6.0 parts Diethylene glycol 6.0 parts Trimethylolpropane 6.0 parts Block copolymer D neutralized potassium 0.1 part (neutralization degree 50 mol%) )
-0.058 calcium chloride aqueous solution 0.18 parts-ion-exchanged water 31.72 parts The above components were mixed and sufficiently stirred, and then filtered through a microfilter having a pore size of 3 µm to obtain the desired ink. When the mass ratio of calcium to the polymer dispersant in the obtained ink was measured, it was calcium: polymer dispersant = 1: 46,000. Moreover, when the obtained ink was centrifuged and the separated supernatant liquid was analyzed, it was found that the block copolymer D was contained in the ink in an amount of 0.1%.

[Example 4]
(Preparation of pigment dispersion IV)
As a polymer dispersant, a methyl ethyl ketone solution of the block copolymer E and a commercially available pigment such as C.I. I. Pigment Yellow 128 was charged into a kneader having a twin screw and kneaded until uniform, and then the solvent was distilled off under reduced pressure while maintaining the internal temperature at 80 ° C. This kneaded product is made into a sheet using two rolls, a predetermined amount of ion-exchanged water and potassium hydroxide as a neutralizing agent, an amount corresponding to a neutralization degree of 85 mol% is added and stirred, and the pigment concentration is 6%. A pigment dispersion IV having a polymer dispersant concentration of 2% was obtained.

(Preparation of ink 4)
-Pigment dispersion IV 50.0 parts-Glycerin 6.0 parts-Diethylene glycol 6.0 parts-Trimethylolpropane 6.0 parts-Sodium neutralized product of block copolymer B 0.25 parts (neutralization degree 50 mol%) )
-1.0% calcium chloride aqueous solution 1.2 parts-Ion-exchanged water 30.55 parts The above components were mixed and sufficiently stirred, and then filtered through a micro filter with a pore size of 3 µm to obtain the desired ink. When the mass ratio of calcium to the polymer dispersant in the obtained ink was measured, it was calcium: polymer dispersant = 1: 230. Further, when the obtained ink was subjected to centrifugal separation treatment and the separated supernatant was analyzed, the result was that 0.23% of the block copolymer B was contained in the ink.

[Example 5]
(Preparation of pigment dispersion V)
As a polymer dispersant, a methyl ethyl ketone solution of the block copolymer A and a commercially available pigment such as C.I. I. Pigment Red 122 was charged into a kneader having a twin screw and kneaded until uniform, and then the solvent was distilled off under reduced pressure while maintaining the internal temperature at 80 ° C. This kneaded product is made into a sheet using two rolls, a predetermined amount of ion-exchanged water and sodium hydroxide as a neutralizing agent are added, an amount corresponding to a neutralization degree of 75 mol% is added and stirred, and a pigment concentration of 7.5 % And a pigment dispersion V having a polymer dispersant concentration of 1.25% was obtained.

(Preparation of ink 5)
-Pigment dispersion V 66.7 parts-Glycerin 6.0 parts-Ethylene glycol 6.0 parts-Triethylene glycol 6.0 parts-Sodium neutralized product of block copolymer F 2.5 parts (neutralization degree 75 mol) %)
・ Polyoxyethylene octadecyl ether 0.5 part (HLB11.3)
-0.05% calcium oxide aqueous solution 1.33 parts-0.1% magnesium nitrate aqueous solution 1.67 parts-ion-exchanged water 9.3 parts After mixing the above ingredients and stirring well, they are filtered through a microfilter with a pore size of 3 µm Thus, the desired ink was obtained. When the mass ratio of the total of calcium and magnesium in the obtained ink and the polymer dispersant was measured, it was magnesium + calcium: polymer dispersant = 1: 2,400. The obtained ink was centrifuged and the separated supernatant was analyzed. As a result, 2.48% of the block copolymer F was contained in the ink.

[Example 6]
(Preparation of pigment dispersion VI)
As a polymer dispersant, a methyl ethyl ketone solution of the above block copolymer A and a commercially available pigment, carbon black (MA100, manufactured by Mitsubishi Chemical Corporation) were charged into a kneader having a twin screw, kneaded until uniform, and the internal temperature was reduced. While maintaining the temperature at 80 ° C., the solvent was distilled off under reduced pressure. This kneaded product is made into a sheet using two rolls, using a predetermined amount of ion-exchanged water and potassium hydroxide as a neutralizing agent, adding an amount corresponding to a neutralization degree of 80 mol%, stirring, and a pigment concentration of 5%, A pigment dispersion VI having a polymer dispersant concentration of 2.5% was obtained.

(Preparation of ink 6)
-Pigment dispersion VI 60.0 parts-Glycerol 6.0 parts-Ethylene glycol 6.0 parts-Triethylene glycol 6.0 parts-Potassium neutralized product of block copolymer C 1.5 parts (neutralization degree 80 mol) %)
・ Polyoxyethylene dodecyl ether 0.3 part (HLB16.5)
-0.1% magnesium chloride aqueous solution 1.5 parts-ion-exchanged water 18.7 parts The above components were mixed and sufficiently stirred, and then filtered through a micro filter with a pore size of 3 µm to obtain the desired ink. The mass ratio of magnesium and polymer dispersant in the ink obtained was magnesium: polymer dispersant = 1: 3,900. The obtained ink was centrifuged and the separated supernatant was analyzed. As a result, the block copolymer C contained 1.46% in the ink.

[Example 7]
(Preparation of ink 7)
-Pigment dispersion V 66.7 parts-6.0 parts of glycerol-6.0 parts of ethylene glycol-6.0 parts of triethylene glycol-0.13 parts of sodium neutralized product of block copolymer F (neutralization degree 75 mol) %)
-Ion-exchanged water 15.17 parts The above components were mixed and sufficiently stirred, and then filtered through a microfilter having a pore size of 3 µm to obtain the desired ink. The obtained ink was centrifuged and the separated supernatant was analyzed. As a result, the block copolymer F was contained in the ink in an amount of 0.12%.

[Example 8]
(Preparation of ink 8)
-Pigment dispersion V 33.35 parts-6.0 parts of glycerin-6.0 parts of ethylene glycol-6.0 parts of triethylene glycol-0.83 parts of sodium neutralized product of block copolymer F (degree of neutralization 75 mol) %)
-Ion-exchanged water 47.82 parts The above components were mixed and sufficiently stirred, and then filtered through a microfilter having a pore size of 3 µm to obtain the desired ink. The obtained ink was centrifuged and the separated supernatant was analyzed. As a result, 0.80% of the block copolymer F was contained in the ink.

[Comparative Example 1]
(Preparation of ink 9)
-Pigment dispersion I 35.0 parts-Glycerol 6.0 parts-Diethylene glycol 6.0 parts-Trimethylolpropane 6.0 parts-Ion-exchanged water 47.0 parts After mixing the above ingredients and stirring sufficiently, the pore size is 3 μm The ink was obtained by filtration through a microfilter.

[Comparative Example 2]
(Preparation of pigment dispersion VII)
As a polymer dispersant, a methyl ethyl ketone solution of the above block copolymer G and a commercially available pigment such as C.I. I. Pigment Red 122 was charged into a kneader having a twin screw and kneaded until uniform, and then the solvent was distilled off under reduced pressure while maintaining the internal temperature at 80 ° C. This kneaded product is made into a sheet using two rolls, a predetermined amount of ion-exchanged water and lithium hydroxide as a neutralizing agent are added, and a corresponding amount with a neutralization degree of 90 mol% is added and stirred, with a pigment concentration of 12%, A pigment dispersion VII having a polymer dispersant concentration of 10% was obtained.

(Preparation of ink 10)
-Pigment dispersion VII 30.0 parts-Glycerin 6.0 parts-Diethylene glycol 6.0 parts-Trimethylolpropane 6.0 parts-Ammonia neutralized product of block copolymer A 0.15 parts (neutralization degree 100 mol%) )
・ Polyoxyethylene nonylphenyl ether 5.0 parts (HLB14.1)
-Ion-exchanged water 46.85 parts The above components were mixed and sufficiently stirred, and then filtered through a microfilter having a pore size of 3 µm to obtain the desired ink. The obtained ink was centrifuged and the separated supernatant was analyzed. As a result, the block copolymer A was contained in the ink in an amount of 0.14%.

[Comparative Example 3]
(Preparation of pigment dispersion VIII)
As a polymer dispersant, a methyl ethyl ketone solution of the block copolymer H and a commercially available pigment, carbon black (MA100, manufactured by Mitsubishi Chemical Corporation) were charged into a kneader having a twin screw and kneaded until uniform, and then the internal temperature was reduced. While maintaining the temperature at 80 ° C., the solvent was distilled off under reduced pressure. This kneaded product is made into a sheet using two rolls, a predetermined amount of ion-exchanged water and sodium hydroxide as a neutralizing agent are added, a corresponding amount having a neutralization degree of 40 mol% is added and stirred, and the pigment concentration is 7.5. %, And Pigment Dispersion VIII having a polymer dispersant concentration of 1.25% was obtained.

(Preparation of ink 11)
-Pigment dispersion VIII 66.7 parts-Glycerol 6.0 parts-Ethylene glycol 6.0 parts-Triethylene glycol 6.0 parts-Sodium neutralized product of block copolymer H 2.5 parts (neutralization degree 75 mol) %)
・ Polyoxyethylene octadecyl ether 0.5 part (HLB11.3)
-0.05% calcium oxide aqueous solution 1.33 parts-0.1% magnesium nitrate aqueous solution 1.67 parts-Ion-exchanged water 9.30 parts After mixing the above ingredients and stirring well, they are filtered through a microfilter with a pore size of 3 μm. Thus, the desired ink was obtained. When the mass ratio of the total of calcium and magnesium in the obtained ink and the polymer dispersant was measured, it was magnesium + calcium: polymer dispersant = 1: 2,400. Further, when the obtained ink was subjected to centrifugal separation treatment and the separated supernatant was analyzed, the result was that 2.48% of the block copolymer H was contained in the ink.

[Comparative Example 4]
(Preparation of pigment dispersion IX)
As a polymer dispersant, a methyl ethyl ketone solution of the above random copolymer I and a commercially available pigment, carbon black (MA100, manufactured by Mitsubishi Chemical Corporation) were charged into a kneader having a biaxial screw, kneaded until uniform, and the internal temperature was reduced. While maintaining the temperature at 80 ° C., the solvent was distilled off under reduced pressure. This kneaded product is made into a sheet using two rolls, a predetermined amount of ion-exchanged water and sodium hydroxide as a neutralizing agent are added, and a corresponding amount with a neutralization degree of 40 mol% is added and stirred, with a pigment concentration of 5%, A pigment dispersion IX having a polymer dispersant concentration of 2.5% was obtained.

(Preparation of ink 12)
-Pigment dispersion IX 60.0 parts-Glycerol 6.0 parts-Ethylene glycol 6.0 parts-Triethylene glycol 6.0 parts-Potassium neutralized product of random copolymer I 1.5 parts (neutralization degree 80 mol) %)
・ Polyoxyethylene dodecyl ether 0.3 part (HLB16.5)
-0.1% calcium chloride aqueous solution 1.5 parts-ion-exchanged water 18.7 parts The above components were mixed and sufficiently stirred, and then filtered through a micro filter with a pore size of 3 µm to obtain the desired ink. When the mass ratio of calcium and polymer dispersant in the obtained ink was measured, calcium: polymer dispersant = 1: 3,900. Further, when the obtained ink was centrifuged and the separated supernatant was analyzed, it was found that 1.33% of the block copolymer I was contained in the ink.

* 1: Degree of unneutralization Calculated as follows from the amount (mol) of acid groups in the copolymer and the addition amount (mol) of the neutralizing agent.
De-neutralization degree (mol%) = 100− (addition amount of neutralizing agent / amount of acid group of copolymer) × 100
* 2: Acid value ratio The value calculated as follows for the ratio of the acid value of the block copolymer (before neutralization) and the polymer dispersant (before neutralization) used as an auxiliary component.
Acid value ratio = acid value of block copolymer (auxiliary component) / acid value of polymer dispersant * 3: content ratio The ratio of the content of the block copolymer and polymer dispersant used as an auxiliary component is as follows: The value calculated in the same way.
Content ratio = content of block copolymer (auxiliary component) / content of polymer dispersant

(Evaluation)
The inks of Examples 1 to 8 and Comparative Examples 1 to 4 were tested for dispersion stability, ejection characteristics, color development, scratch resistance, and water resistance. As for color development, scratch resistance, water resistance, and ejection characteristics, an inkjet recording apparatus P having an on-demand type multi-recording head that ejects ink by applying thermal energy corresponding to the recording signal to each ink. -660CII (manufactured by Canon Finetech Co., Ltd.) was respectively mounted, and printing was performed on glossy paper SP101 (manufactured by Canon Inc.) for evaluation. As a result, as shown in Table 3, the inks of any of the examples showed results showing better dispersion stability and ejection stability than the inks of the comparative examples. In addition, the inks of the examples all had good results in the color development, scratch resistance and water resistance of the printed image.

○：粒子径増加率（％）が５％未満である。
△：粒子径増加率（％）が５％以上１０％未満である。
×：粒子径増加率（％）が１０％以上である。 * 4: Dispersion stability Each ink is subjected to a thermal stability test at 100 ° C for 4 hours, the particle diameter before and after the test is measured, and the particle diameter increase / decrease rate (%) is calculated by the following formula. did. A dynamic light scattering method (trade name: Laser particle size analysis system PARIII; manufactured by Otsuka Electronics Co., Ltd.) was used for the measurement of the particle size. The evaluation criteria were as follows.

A: The particle diameter increase rate (%) is less than 5%.
Δ: Particle diameter increase rate (%) is 5% or more and less than 10%.
X: The particle diameter increase rate (%) is 10% or more.

* 5: Discharge characteristics After each ink is stored at 70 ° C for 1 month, in a 10% humidity environment at 15 ° C, a 100% solid image is printed, and after resting for 3 minutes, a 100% solid image is printed again. The obtained images were evaluated according to the following evaluation criteria.
A: There are no white stripes and printing is normal.
○: Slight white streaks are observed at the beginning of printing.
Δ: White streaks are observed in the entire image.
X: An image is hardly printed.

* 6: Color developability An image was printed with each ink stored at 70 ° C. for 1 month, and the image was evaluated according to the following evaluation criteria.
A: There is no bleeding and the saturation is high.
○: No bleeding but slightly low saturation.
Δ: Bleeding is observed.
X: There is much bleeding and saturation is low.

* 7: Scratch resistance 30 seconds after printing, tap water is sprayed on the printing surface, then a Kimwipe (trade name) is placed on it, and a 500 g / 12.56 cm ² weight is placed on it, 5 reciprocations In this case, the dirt on the blank paper portion, solid images, and the rubbing condition of the character printing portion were evaluated according to the following evaluation criteria.
A: There is no dirt on the blank paper portion, and there is no rubbing of the solid image and the character printing portion.
○: There is almost no dirt on the blank paper portion, and there is no rubbing of the solid image and the character print portion.
Δ: Slightly dirty in the blank paper area, and after rubbing the solid image and the character print area slightly.
×: The white paper portion is dirty and a solid image and a part of the character print portion are scraped off.

* 8: Water resistance 30 seconds after printing, the printed matter is left in tap water for 24 hours, and after measuring the reflection density of the image after drying the water, the reflection density before and after the water resistance test is measured. The residual rate was determined and used as a measure of water resistance. The evaluation criteria were as follows.
○: Image density residual rate is 90% or more.
Δ: Image density remaining rate is 80% or more and less than 90%.
X: Residual rate of image density is less than 80%.

  As described above, according to the present invention, it is possible to provide an ink capable of stably recording an image having high fastness and excellent quality over a long period of time in any case. An ink jet recording method, an ink cartridge, and an ink jet recording apparatus capable of recording an image with excellent quality can be provided.

It is a schematic diagram for demonstrating the structure of an ink cartridge. It is a schematic diagram for demonstrating the structure of an inkjet recording head. It is a perspective view of an inkjet recording device. It is the schematic of the recovery processing system in an inkjet recording device. It is a schematic sectional drawing which shows another structural example of an inkjet recording head.

Explanation of symbols

100: ink cartridge 101: ink bag 102: rubber stopper 103: needle 104: tube 201: base plate 202: ink nozzle (discharge port)
203: Partition 204 Nozzle heater 205: Common liquid chamber 206: Substrate 207: Top plate 300: Recording device 301: Roll supply unit 302: Recording medium (roll paper)
303: Recording head (black)
304: Recording head (cyan)
305: Recording head (magenta)
306: Recording head (yellow)
307: Ink cartridge (black)
308: Ink cartridge (cyan)
309: Ink cartridge (magenta)
310: Ink cartridge (yellow)
311: Cap mechanism 312: Conveying motor 313: Conveying belt 400: Cap 401: Sub tank 402: Pressurizing pump 403: Suction pump 404 a: Supply valve 404 b: Recovery valve 404 c: Atmospheric release valve 404 d: Recycling valve 405: Filter 406: Face (Nozzle) surface 80: ink flow path 81: orifice plate 82: diaphragm 83: piezoelectric element 84: substrate 85: discharge port

Claims (12)

In an inkjet recording ink containing at least a pigment dispersion dispersed with a polymer dispersant, an auxiliary component, and water,
(A) The polymer dispersant has at least one hydrophobic block and at least one hydrophilic block, and each block is composed of a block copolymer obtained by polymerizing vinyl ethers. The polymer dispersant has an acid value in the range of 30 mg to 250 mg-KOH / g, and 10 to 50 mol% of the acid groups are unneutralized; and (b) the auxiliary component is at least An ink for ink jet recording, comprising one hydrophobic block and at least one hydrophilic block, wherein each block is composed of a block copolymer obtained by polymerizing vinyl ethers.   The block in which the auxiliary component has an acid value in the range of 0.1 to 0.5 times the acid value of the polymer dispersant, and 10 mol% to 50 mol% of the acid groups are unneutralized The ink for inkjet recording according to claim 1, which is a copolymer.   The ink for inkjet recording according to claim 1, wherein the auxiliary component is contained in a mass ratio of 0.1 to 3.0 times with respect to the polymer dispersant.   Furthermore, the ink for inkjet recording of Claim 1 containing a calcium and / or magnesium compound.   2. The ink for ink jet recording according to claim 1, wherein the neutralizing agent of at least one block copolymer of the polymer dispersant and the auxiliary component is a compound containing an alkali metal salt.   The hydrophilic block of at least one block copolymer of the polymer dispersant and the auxiliary component is composed of a block composed of vinyl ethers having a nonionic hydrophilic group and a vinyl ether having an anionic hydrophilic group. The ink for ink-jet recording according to claim 1, comprising at least a block which is formed.   The block copolymer of at least one of the polymer dispersant and the auxiliary component is composed of a block composed of a hydrophobic vinyl ether, a block composed of a vinyl ether having a nonionic hydrophilic group, and an anionic hydrophilic group The ink for ink jet recording according to claim 1, wherein the ink is composed at least in the order of blocks composed of vinyl ethers having the following.   The ink for inkjet recording according to any one of claims 1 to 7, wherein the ink is applied to a recording material by applying energy to the ink and flying the ink to the recording material. An ink jet recording method.   The ink jet recording method according to claim 8, wherein the energy is thermal energy.   9. The ink jet recording method according to claim 8, wherein the recording material is a recording material having a coating layer for receiving ink on at least one surface.   An ink cartridge comprising an ink containing portion containing ink, wherein the ink is the ink for ink jet recording according to any one of claims 1 to 7.   An ink jet recording apparatus comprising: an ink cartridge having an ink containing portion containing ink; and a head portion for discharging the ink, wherein the ink is for ink jet recording according to any one of claims 1 to 7. An ink jet recording apparatus comprising ink.

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