JP2010144077A - Ink for inkjet recording, recording method and recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink for inkjet recording, giving a recorded article having excellent image fastness, free from curling trouble and coping with high-resolution image recording while keeping good and stable response even in the case of discharging in wide driving frequency and driving voltage ranges. <P>SOLUTION: The ink for inkjet recording contains an aqueous medium, a water-insoluble color material and a dispersant for dispersing the water-insoluble color material in the aqueous medium, wherein the ink for inkjet recording contains a polyglycerol, and the dispersant is a block polymer containing a hydrophobic segment, a nonionic hydrophilic segment and an ionic hydrophilic segment. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention is excellent in fastness of recorded matter, and even if it is applied in a large amount to a recording medium containing cellulose, the curling of the recording medium does not become a problem, and it is good and stable even when ejected with a wide range of driving frequencies and driving voltages The present invention relates to an ink for inkjet recording that can maintain the responsiveness. The present invention also relates to an ink jet recording method and an ink jet recording apparatus using the ink for ink jet recording.

  In the ink jet recording method, recording is performed by ejecting small droplets of ink for ink jet recording (hereinafter also abbreviated as “ink”) and attaching them to a recording medium such as paper. The thermal ink jet method that ejects droplets by applying thermal energy to ink and generating bubbles can easily realize high-density, multi-nozzle recording heads and record high-resolution, high-quality images at high speed. There is a proposal that can be made (see Patent Document 1).

  In recent years, the size of ink droplets to be ejected has been reduced in order to cope with extremely high-quality ink-jet recorded images at the silver salt photography level, and now the ink droplet amount is about 5 pl (picoliter). The following inkjet printers are commercially available. Further, with respect to the recording speed, further higher speed has been demanded, and accordingly, it is urgently required to cope with a higher driving frequency during ejection.

  Ink used for ink jet recording generally contains water as a main component and contains a water-soluble high-boiling solvent such as glycol for the purpose of preventing drying and improving the anti-sticking property of the recording head. When recording on a recording medium containing cellulose typified by plain paper or a small amount of coated paper using such ink, if a large amount of ink is applied in a short time to an area of a certain area or more, curling will occur. The problem that occurs occurs. This problem was not a problem when recording characters centered, which was the mainstream in the past, because the amount of ink shot was small, but recording a large amount of ink such as Internet homepages or photographic images on plain paper. At that time, it is a big problem to be solved.

  In order to solve these problems, water-based ink compositions containing various anti-curl solvents have been proposed (see Patent Document 2). When such a substance is used, a certain degree of effect is recognized with respect to curling resistance, but further improvement is desired for the compatibility between response at the time of high driving frequency ejection and curling resistance.

  Apart from this, for the recorded matter such as photographic images as described above, not only the curl resistance but also the image fastness such as the water resistance and weather resistance is desired to be further improved. Therefore, studies have been actively conducted on the use of pigments as coloring materials in ink. When a pigment is used as a coloring material for an aqueous inkjet ink, it is important to stably disperse the pigment in an aqueous medium. In general, in order to uniformly disperse the pigment in the aqueous medium, for example, a hydrophilic group for stably dispersing the pigment in the aqueous medium, and a hydrophobic portion for physically adsorbing to the hydrophobic pigment surface A method of using a resin dispersant having a viscosity is employed (for example, see Patent Document 3). In addition, a method of hydrophilizing the pigment surface by an oxidation reaction or the like (for example, see Patent Document 4) has been adopted. However, when an ink obtained by a method of hydrophilizing the pigment surface by an oxidation reaction or the like is printed on a recording medium, the resulting image may not have sufficient scratch resistance or marker resistance with a fluorescent marker pen.

  On the other hand, when printing the ink obtained by the method using the resin dispersant on the recording medium, the more the amount of the dispersant in the ink, the more the resin covers the surface of the pigment. It is possible to improve. However, since the viscosity of the ink increases as the amount of the dispersant increases, the ink ejection stability at a high driving frequency is lowered. In particular, this tendency is remarkable when the thermal ink jet method is used. Further, as a means for improving the dispersion stability and ejection stability, there is a method of increasing the ratio of the hydrophilic group of the dispersant. When such ink is printed on the recording medium, the resin on the recording medium Since hydrophilicity becomes high, water resistance and marker resistance are often not obtained.

  In response to these problems, an ink composition has been proposed in which both the discharge stability of the pigment ink and the image fastness of the recorded material are compatible (see Patent Document 5). However, it cannot be said that sufficient performance has been obtained in terms of compatibility with ejection stability at a high drive frequency, a wide range of drive voltages, and curling resistance.

  The outline of each issue is shown below.

1. Marker resistance When the ink is printed on a recording medium and the obtained recorded matter is traced with a marker such as a fluorescent pen, the recorded matter may be stained. This is not a problem with inks of a type in which the penetrating power is strong and the colorant in the ink is absorbed in a recording medium such as a dye, but the recording is such that the penetrating power is weak and the colorant is a pigment. This is often a problem with ink types that stay on the media. This phenomenon is particularly remarkable in the case of a self-dispersing pigment ink that does not use a dispersing resin or the like. Also, in the resin-dispersed pigment inks, those having a high proportion of hydrophilic groups in the dispersed resin as described above, the hydrophilic polymer on the pigment particle surface is redissolved by water or a water-soluble organic solvent in the marker. As a result, the printed matter and the marker may be soiled.

2. Curling resistance When a large amount of water-based ink is applied to a recording medium containing cellulose typified by plain paper, a so-called curling phenomenon occurs, and in some cases, the paper is rounded into a cylindrical shape.

  The mechanism of curling is thought to be due to the fact that in the process of drying the paper at the paper making stage, water evaporates with tension applied in a certain direction, and hydrogen bonds are formed between the celluloses. When water-based ink adheres to the paper in this state, the hydrogen bond between celluloses is broken by water and the bonding part is replaced by water, but when the water evaporates, hydrogen bonds between celluloses are formed again. At the time of re-formation, it is considered that the paper is contracted to the ink adhesion surface side because no tension is applied, and as a result, curling occurs.

This phenomenon, which was difficult to occur in recording with a small amount of ink at the center of characters, has become a major problem in recent years when the frequency of graphic printing has increased, and a marked improvement in curling resistance is required. The curl varies depending on the area where the ink is applied and the amount of ink applied. However, the curl becomes a problem particularly when the recording area is 15 cm ² or more and the recording amount is 0.03 to 30 mg / cm ² .

3. Discharge stability When using a pigment ink in an ink jet recording apparatus that performs recording by ejecting ink from the recording head by the action of energy, those that have poor dispersion stability cause a significant obstacle to the discharge stability, It was easy to generate printing defects. In particular, when performing recording by discharging droplets by applying thermal energy, this problem is likely to occur when a conventional aqueous pigment ink is used. Specifically, when a pulse is applied to the ink, deposits are formed on the thin film resistor due to the heat at a certain driving voltage, the ink is not sufficiently foamed, and droplet ejection cannot respond to the applied pulse. In some cases, discharge occurred.
Japanese Patent Publication No. 61-59911 JP-A-6-157955 Japanese Patent Laid-Open No. 9-241564 JP-A-8-3498 JP 2002-47438 A

  The inventors of the present invention have energetically studied ink for ink jet recording that ensures the dispersion stability and ejection stability of the pigment ink, and does not cause curling of the recording medium even with respect to the recording medium containing cellulose. went. Furthermore, energetically studied ink jet recording inks having excellent image fastness such as water resistance, marker resistance and scratch resistance of printed matter. As a result, it has been found that an ink having a composition containing a specific dispersion resin and an organic compound can achieve the above-described object at an extremely high level, and has led to the present invention.

  Therefore, the object of the present invention is excellent in image fastness of recorded matter, curl is not a problem, and maintains a good and stable response even when ejected with a wide range of driving frequencies and driving voltages, while maintaining high definition. Another object of the present invention is to provide an ink for ink jet recording that can cope with various image recording.

  Another object of the present invention is to provide an ink jet recording method capable of stably forming a high-quality image.

  A further object of the present invention is to provide an ink jet recording apparatus which can be applied to the above ink jet recording method.

  The above object is achieved by the present invention described below. That is, the present invention relates to an ink jet recording ink containing an aqueous medium, a water-insoluble colorant, and a dispersant for dispersing the water-insoluble colorant in the aqueous medium, wherein the ink jet recording ink contains polyglycerin. An ink for inkjet recording, wherein the dispersant is a block polymer containing a hydrophobic segment, a nonionic hydrophilic segment, and an ionic hydrophilic segment.

  The present invention also provides an ink jet recording method and an ink jet recording apparatus using the ink having the above-described structure.

  According to the present invention, the recorded image has excellent image fastness, curl is not a problem, and a high-definition image is maintained while maintaining good and stable responsiveness even when ejected at a wide range of driving frequencies and driving voltages. Ink for ink jet recording that can cope with recording can be obtained.

  Further, according to the present invention, it is possible to obtain an ink jet recording method capable of stably forming a high-quality image.

  Furthermore, according to the present invention, an ink jet recording apparatus applicable to the above ink jet recording method can be obtained.

  Hereinafter, the present invention will be described in more detail with reference to preferred embodiments. An ink for ink jet recording according to the present invention (hereinafter sometimes abbreviated as “ink”) includes at least a water-insoluble colorant, a dispersant having a specific structure for dispersing the water-insoluble colorant, an aqueous medium, and polyglycerin. It is characterized by including. First, these components will be described.

(Water-insoluble colorant)
The water-insoluble colorant contained in the ink of the present invention can be either a dye or a pigment as long as it is dispersed by a resin, but is preferably a pigment in consideration of weather resistance and the like. The amount added to the ink is not limited to this range, but is 0.1 to 15% by mass, preferably 0.2 to 12% by mass, and more preferably 0.3 to 10% by mass with respect to the total amount of the ink. %. Almost all of the water-insoluble disperse dyes and oil-soluble dyes described in the COLOR INDEX can be used as the dye used in the ink. Specific examples of the pigment suitable in the present invention include the following, but are not limited thereto.

Carbon black is preferably used as the pigment used in the black ink. For example, carbon black pigments such as furnace black, lamp black, acetylene black and channel black. Further, those having a primary particle diameter of 15 to 40 nm, a specific surface area by BET method of 50 to 300 m ² / g, a DBP oil absorption of 40 to 150 ml / 100 g, and a volatile content of 0.5 to 10% by mass are preferable. Used.

  As the pigment used in the color ink, an organic pigment is preferably used. Specific examples include insoluble azo pigments such as toluidine red, toluidine maroon, Hansa yellow, benzidine yellow, and pyrazolone red, and water-soluble azo pigments such as ritole red, helio bordeaux, pigment scarlet, and permanent red 2B. Moreover, derivatives from vat dyes such as alizarin, indanthrone and thioindigo maroon, phthalocyanine pigments such as phthalocyanine blue and phthalocyanine green, quinacridone pigments such as quinacridone red and quinacridone magenta, and the like can be mentioned. Also, perylene pigments such as perylene red and perylene scarlet, and isoindolinone pigments such as isoindolinone yellow and isoindolinone orange can be used. Further, imidazolone pigments such as benzimidazolone yellow, benzimidazolone orange, and benzimidazolone red, and pyranthrone pigments such as pyranthrone red and pyranthrone orange are listed. Further, thioindigo pigments, condensed azo pigments, thioindigo pigments, diketopyrrolopyrrole pigments and the like can be mentioned. Examples thereof include pigments such as flavanthron yellow, acylamide yellow, quinophthalone yellow, nickel azo yellow, copper azomethine yellow, perinone orange, anthrone orange, dianthraquinonyl red, and dioxazine violet.

  The organic pigment is indicated by a color index (CI) number. C. I. Pigment Yellow 12, 13, 14, 17, 20, 24, 55, 74, 83, 86, 93, 97, 98, 109, 110, 117, 120, 125, 128, 137, 138, 139, 147, 148, 150, 151, 153, 154, 155, 166, 168, 180, 185, etc. C. I. Pigment Orange 16, 36, 43, 51, 55, 59, 61, 71 etc. C. I. Pigment Red 9, 48, 49, 52, 53, 57, 97, 122, 123, 149, 168, 175, 176, 177, 180, 192, 202, 209, 215, 216, 217, 220, 223, 224, 226, 227, 228, 238, 240, 254, 255, 272, etc. C. I. Pigment violet 19, 23, 29, 30, 37, 40, 50, C.I. I. Pigment blue 15, 15: 1, 15: 3, 15: 4, 15: 6, 22, 60, 64, C.I. I. Pigment Green 7, 36 etc. C. I. Examples thereof include CI Pigment Brown 23, 25, 26, and the like. Other pigments than the above can also be used. Among the exemplified pigments, C.I. I. Pigment Yellow 13, 17, 55, 74, 93, 97, 98, 110, 128, 139, 147, 150, 151, 154, 155, 180, 185, C.I. I. Pigment red 122, 202, 209, C.I. I. Pigment Blue 15: 3 and 15: 4 are more preferable.

(Dispersant)
The dispersant for dispersing the pigment, which characterizes the present invention, includes at least a hydrophobic segment, a nonionic hydrophilic segment, and an ionic hydrophilic segment. In particular, a triblock polymer having a structure in which a hydrophobic segment, a nonionic hydrophilic segment, and an ionic hydrophilic segment are arranged in this order is preferable. When the example of a specific segment is given, an acryl, methacryl type block copolymer etc. will be mentioned as an ionic hydrophilic segment. Moreover, polystyrene etc. are mentioned as a hydrophobic segment. Moreover, polyoxyethylene etc. are mentioned as a nonionic hydrophilic segment. These conventionally known block segments can be used. In practicing the present invention, a dispersant in which each segment as a block contains a polyvinyl ether structure as a repeating unit structure is preferable. In particular, when the head polymer using thermal energy, that is, a thermal ink jet head is driven at a high driving frequency, for example, 10 KHz or more, the above-described block polymer is used in the present invention, and the effect of improving the discharge property is more remarkable. become.

  A preferred specific structure of the ionic hydrophilic segment of polyvinyl ether includes, but is not limited to, the repeating unit structure represented by the following general formula (1).

(Wherein R ⁰ represents -X- (COOH) r, -X- (COO-M) r. X represents a linear, branched or cyclic alkylene group having 1 to 20 carbon atoms, or- ^{(CH (R 5) -CH (} R 6) -O) p- (CH 2) m- or _{- (CH 2) m- (O} ) n- (CH 2) q- , or at least their methylene group 1 represents a structure substituted with a carbonyl group or an aromatic ring structure, r represents 1 to 2, p represents an integer of 1 to 18, m represents an integer of 0 to 35, n represents 1 or Represents 0, q represents an integer of 0 to 17, M represents a monovalent or polyvalent cation, R ⁵ and R ⁶ represent an alkyl group, and R ⁵ and R ⁶ may be the same or different; Good.)

  Furthermore, preferred specific examples of the repeating unit structure of the hydrophobic segment or nonionic hydrophilic segment include a repeating unit structure represented by the following general formula (2), but are not limited thereto.

(In the formula, R ¹ is a linear, branched or cyclic alkyl group having 1 to 18 carbon atoms, -Ph, -Pyr, -Ph-Ph, -Ph-Pyr,-(CH (R ⁵ )- CH (R ⁶ ) —O) p—R ⁷ and — (CH ₂ ) m— (O) n—R ^{7 are} selected, and the hydrogen atom in the aromatic ring is linear or branched having 1 to 4 carbon atoms. And the carbon atom in the aromatic ring may be substituted with a nitrogen atom, p is an integer of 1 to 18, m is an integer of 1 to 36, and n is 0 or 1. R ⁵ , R ⁶ each independently represents a hydrogen atom or —CH ₃ , R ⁷ represents a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 18 carbon atoms, —Ph, —Pyr, —Ph— _{Ph, -Ph-Pyr, -CHO,} -CH 2 CHO, -CO-CH = CH 2, -CO-C (C _{3) =} CH _2, is selected from -CH 2 COOR _8, when ^{R 7} is other than hydrogen atom, the hydrogen atom bonded to a carbon atom in ^{R 7} is a linear or branched having 1 to 4 carbon atoms And a carbon atom in the aromatic ring can be substituted with a nitrogen atom, and R ⁸ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. (Ph represents a phenyl group, and Pyr represents a pyridyl group.)
Specific examples of the repeating unit structure represented by the general formula (1) are shown below.

(M ₁ represents hydrogen, lithium, sodium, potassium, or ammonium, and Ph represents a phenylene group.)
Specific examples of the repeating unit structure of the hydrophobic segment represented by the general formula (2) are shown below.

(Ph represents a phenyl group or a phenylene group, and C ₁₀ H ₇ represents a naphthyl group.)
Specific examples of the repeating unit structure of the nonionic hydrophilic segment represented by the general formula (2) are shown below.

  The amount of the dispersant in the ink is in the range of 0.5 to 10% by mass, preferably 0.8 to 8% by mass, and more preferably 1 to 6% by mass with respect to the total amount of the ink. If the content of the dispersant is higher than this range, it becomes difficult to maintain a desired ink viscosity.

  Moreover, it is preferable that the monomer ratio which comprises a nonionic hydrophilic segment and an ionic hydrophilic segment is the range of 20: 1 to 1: 2, respectively, and it is more preferable that it is the range of 10: 1 to 1: 1. Furthermore, when the degree of polymerization of the monomers constituting the hydrophobic block segment, the nonionic hydrophilic segment, and the ionic hydrophilic segment is 10, the nonionic hydrophilic segment is 8 or less and the ionic hydrophilic segment is 5 or less. This is also a preferable condition. Within this range, the desired ejection stability and image fastness can be obtained by the combined use effect with polyglycerin.

(Aqueous medium)
The aqueous medium contained in the ink according to the present invention contains water and polyglycerin as essential components, but the content in the ink is preferably 30% by mass or more in the case of water with respect to the total mass of the ink. Moreover, it is preferable that it is 95 mass% or less. In the case of polyglycerol, it is preferably 3 to 40% by mass, and more preferably 5 to 35% by mass. In consideration of the curl suppressing effect, when polyglycerin alone or in combination with another curl suppressing solvent, the total amount is preferably 12% by mass or more, more preferably 15% by mass with respect to the total mass of the ink. More preferably. Furthermore, as polyglycerol to be used, diglycerol and triglycerol are preferable, and diglycerol is more preferable. The curl-suppressing solvent preferably used in combination is particularly preferably a polyalkylene glycol having a molecular weight of 200 to 1,000, 1,2,6-hexanetriol, sorbitol, trimethylolpropane and the like, but is not limited thereto. In addition to this, an organic solvent can be used as necessary. Examples thereof include alkyl alcohols having 1 to 5 carbon atoms such as methyl alcohol, propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, and n-pentanol. Moreover, amides such as dimethylformamide and dimethylacetamide; ketones or ketoalcohols such as acetone and diacetone alcohol; ethers such as tetrahydrofuran and dioxane, and the like. Diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol; ethylene glycol, propylene glycol, trimethylene glycol, 1,4-butanediol, 1,5-pentanediol and other alkylene groups are 2 to 2 Examples include alkylene glycols containing 6 carbon atoms. Further, lower alkyl ethers of glycols such as ethylene glycol monomethyl (or ethyl) ether, diethylene glycol monomethyl (or ethyl) ether, triethylene glycol monomethyl (or ethyl, butyl) ether, and the like can be given. In addition, lower dialkyl ethers of polyhydric alcohols such as triethylene glycol dimethyl (or ethyl) ether and tetraethylene glycol dimethyl (or ethyl) ether are listed. Moreover, alkanolamines, such as monoethanolamine, diethanolamine, and triethanolamine, etc. are mentioned. Moreover, sulfolane, N-methyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, urea, ethylene urea, glycerin, glucose, bishydroxyethyl sulfone and the like can be mentioned.

(Surfactant)
In the ink according to the present invention, it is preferable to contain a surfactant in the ink in order to obtain a more balanced ejection stability. Among these, it is preferable to use a nonionic surfactant in combination. Among the nonionic surfactants, polyoxyethylene alkyl ethers and ethylene oxide adducts of acetylene glycol are particularly preferable. These nonionic surfactants have an HLB (Hydrophile-Lipophile Balance) value of 10 or more. The content of the surfactant used in this manner is 0.01 to 5% by mass, preferably 0.05 to 4% by mass, and more preferably 0.1 to 3% by mass with respect to the total amount of the ink.

(Other additives)
In addition to the above-described components, the ink according to the present invention includes, as necessary, a viscosity modifier, an antifoaming agent, an antiseptic, and an antifungal agent in order to obtain an ink having a desired physical property value. An antioxidant or the like can be added. The additive is preferably selected so that the surface tension of the ink is 25 mN / m or more, preferably 28 mN / m or more.

(recoding media)
The recording medium used in the present invention contains cellulose. Typically, it is so-called plain paper. When a large amount of water-based ink is applied to such a recording medium, a so-called curling phenomenon occurs, and in some cases, the paper is rounded into a cylindrical shape. Therefore, the present invention can be very suitably used for an ink jet recording method using a recording medium containing cellulose.

(Inkjet recording device)
As described above, the curl varies depending on the area where the ink is applied and the amount of ink applied, and is particularly noticeable when recording in a range of 15 cm ² or more as the recording area and 0.03 to 30 mg / cm ² as the amount of ink applied. It becomes a problem. Therefore, the present invention can be particularly suitably used for an ink jet recording method under such conditions.

  FIG. 1 is a schematic perspective view showing a main part of an example of a liquid discharge head as a liquid discharge head of a discharge method that communicates bubbles with the atmosphere during discharge and an ink jet printer that is a liquid discharge apparatus using the head.

  In FIG. 1, the ink jet printer includes a conveyance device 1030 that intermittently conveys a sheet 1028 as a recording medium provided in a casing 1008 along a longitudinal direction in a direction indicated by an arrow P in the drawing. Yes. Furthermore, a recording unit 1010 that is reciprocated substantially in parallel with the guide shaft 1014 in an arrow S direction substantially orthogonal to the conveyance direction P of the paper 1028 by the conveying device 1030, and a drive unit that reciprocates the recording unit 1010. The moving drive unit 1006 is included.

  The conveying device 1030 includes a pair of roller units 1022a and 1022b that are arranged to face each other substantially in parallel, a pair of roller units 1024a and 1024b, and a drive unit 1020 for driving these roller units. Yes. With this configuration, when the driving unit 1020 of the transport device 1030 is activated, the paper 1028 is sandwiched between the roller units 1022a and 1022b and the roller units 1024a and 1024b, and is intermittently fed in the direction of the arrow P. It will be transported. The movement drive unit 1006 includes a pulley 1026a disposed on a rotation shaft that is disposed to be opposed at a predetermined interval, a belt 1016 wound around the pulley 1026b, and a roller unit 1022a. Further, the motor 1018 is configured to drive a belt 1016 arranged substantially parallel to the roller unit 1022b and connected to the carriage member 1010a of the recording unit 1010 in the forward direction and the reverse direction.

  When the motor 1018 is activated and the belt 1016 rotates in the arrow R direction, the carriage member 1010a of the recording unit 1010 is moved in the arrow S direction by a predetermined movement amount. When the motor 1018 is activated and the belt 1016 rotates in the direction opposite to the arrow R direction shown in the drawing, the carriage member 1010a of the recording unit 1010 moves in a predetermined direction in the direction opposite to the arrow S direction. It will be moved by the amount. Further, a recovery unit 1026 for performing an ejection recovery process of the recording unit 1010 is opposed to the ink ejection port array of the recording unit 1010 at one end of the movement driving unit 1006 at a position that becomes the home position of the carriage member 1010a. Is provided.

  The recording unit 1010 is provided with ink jet cartridges (hereinafter simply referred to as cartridges) 1012Y, 1012M, 1012C, and 1012B detachably with respect to the carriage member 1010a for each color.

  FIG. 2 shows an example of an ink jet cartridge that can be mounted on the above-described ink jet recording apparatus. The cartridge 1012 in the illustrated example is of a serial type, and the main part is composed of the ink jet head 100 and an ink tank 1001 that is an ink containing part for containing ink.

  The inkjet head 100 is formed with a number of ejection ports 832 for ejecting ink, and the ink is supplied from the ink tank 1001 through an ink supply passage (not shown) to a common liquid chamber (not shown) of the liquid ejection head 100. Has been led to. In the cartridge 1012 shown in FIG. 2, the ink jet head 100 and the ink tank 1001 are integrally formed so that liquid can be supplied into the ink tank 1001 as necessary. A structure in which the ink tank 1001 is connected to the inkjet head 100 in a replaceable manner may be employed. An ink jet cartridge provided with an ink jet head is a recording unit.

  Next, the present invention will be described more specifically with reference to examples and comparative examples. In the text, “%” is based on mass unless otherwise specified.

(Preparation of dispersion resin 1)
First, using the respective monomers of ABC in Table 1 as raw materials, the polymerization ratio A: B: C = 110: 45: 14, number average molecular weight Mn = by the cation living polymerization method described in JP-A No. 2003-261738, etc. An ABC type block polymer having a number average molecular weight and a weight average molecular weight of 22,000, Mn / Mw = 1.2, was prepared. Further, the obtained polymer was neutralized with an aqueous potassium hydroxide solution and diluted with ion-exchanged water to obtain a homogeneous aqueous polymer solution. Further, the triblock polymer in which the C component became free carboxylic acid was obtained by neutralizing with hydrochloric acid in the aqueous dispersion. In addition, NMR and GPC were used for the identification of the compound.

(Preparation of pigment dispersion (1))
15 g of the carboxylic acid type triblock polymer and 10 g of carbon black obtained from the preparation of the dispersion resin 1 were co-dissolved in 200 g of tetrahydrofuran (THF) and converted into an aqueous phase using 400 g of distilled water, and then THF was removed. The resulting pigment dispersion was adjusted for concentration by removing water to obtain a pigment dispersion (1) having a pigment concentration of 5% by mass.

(Preparation of pigment dispersion (2))
In the preparation of the pigment dispersion (1), carbon black was changed to C.I. I. A pigment dispersion (2) was obtained in the same procedure except that the pigment blue 15: 3 was used.

(Preparation of pigment dispersion (3))
In the preparation of the pigment dispersion (1), carbon black was changed to C.I. I. A pigment dispersion (3) was obtained in the same procedure except that the pigment red 122 was used.

(Preparation of pigment dispersion (4))
In the preparation of the pigment dispersion (1), carbon black was changed to C.I. I. A pigment dispersion (4) was obtained in the same procedure except that the pigment yellow 128 was used.

(Preparation of dispersion resin 2)
The polymerization ratio A: B: C = 95: 63: 11, Mn = 21,000, Mn by the cation living polymerization method described in JP-A No. 2003-261738 or the like using the respective ABC monomers in Table 2 as raw materials. An ABC type block polymer with /Mw=1.3 was produced. Further, the obtained polymer was neutralized with an aqueous potassium hydroxide solution and diluted with ion-exchanged water to obtain a homogeneous aqueous polymer solution. Further, the triblock polymer in which the C component became free carboxylic acid was obtained by neutralizing with hydrochloric acid in the aqueous dispersion. In addition, NMR and GPC were used for the identification of the compound.

(Preparation of pigment dispersion (5))
12 g of carboxylic acid type triblock polymer and 12 g of carbon black obtained from the preparation of the dispersion resin 2 were co-dissolved in 200 g of tetrahydrofuran (THF) and converted into an aqueous phase using 400 g of distilled water, and then THF was removed. The resulting pigment dispersion was adjusted for concentration by removing water to obtain a pigment dispersion (5) having a pigment concentration of 5% by mass.

(Preparation of pigment dispersion (6))
In the preparation of the pigment dispersion (5), carbon black was changed to C.I. I. A pigment dispersion (6) was obtained in the same procedure except that Pigment Blue 15: 3 was used.

(Preparation of pigment dispersion (7))
In the preparation of the pigment dispersion (5), carbon black was changed to C.I. I. A pigment dispersion (7) was obtained in the same procedure except that the pigment red 122 was used.

(Preparation of pigment dispersion (8))
In the preparation of the pigment dispersion (5), carbon black was changed to C.I. I. A pigment dispersion (8) was obtained in the same procedure except that the pigment yellow 128 was used.

(Preparation of dispersion resin 3)
Using the AB monomers in Table 1 as raw materials, the polymerization ratio A: B = 105: 42, Mn = 18,000, Mn / Mw = 1 by the cationic living polymerization method described in JP-A No. 2003-261738, etc. .2 AB type diblock polymer was prepared. In addition, NMR and GPC were used for the identification of the compound.

(Preparation of pigment dispersion (9))
15 g of AB type diblock polymer and 10 g of carbon black obtained from the preparation of the dispersion resin 3 were co-dissolved in 200 g of tetrahydrofuran (THF) and converted into an aqueous phase using 400 g of distilled water, and then THF was removed. The obtained pigment dispersion was adjusted in concentration by removing water to obtain a pigment dispersion (9) having a pigment concentration of 5% by mass.

(Preparation of dispersion resin 4)
A random polymer having a polymerization ratio of A: B: C = 95: 63: 11, Mn = 21,000, and Mn / Mw = 1.3 was prepared by a conventional random polymerization method using ABC monomers shown in Table 2 as raw materials. did. Further, the obtained polymer was neutralized with an aqueous potassium hydroxide solution and diluted with ion-exchanged water to obtain a homogeneous aqueous polymer solution. Furthermore, the polymer was neutralized with hydrochloric acid in an aqueous dispersion to obtain a random polymer in which the C component was a free carboxylic acid. In addition, NMR and GPC were used for the identification of the compound.

(Preparation of pigment dispersion (10))
12 g of a random polymer obtained from the preparation of the dispersion resin 4, C.I. I. 12 g of CI Pigment Blue 15: 3 was co-dissolved in 200 g of tetrahydrofuran (THF), converted to an aqueous phase using 400 g of distilled water, and then THF was removed. The resulting pigment dispersion was adjusted for concentration by removing water to obtain a pigment dispersion (10) having a pigment concentration of 5% by mass.

(Preparation of inks 1 to 16)
The inks 1 to 16 were prepared by using the above pigment dispersions (1) to (10), adding each component according to the formulation shown in Table 3 to a predetermined concentration, thoroughly mixing and stirring them, and pore size 2 The solution was filtered under pressure with a 5 μm microfilter (manufactured by Fuji Film).

<Evaluation>
Inks 1 to 22 obtained in Examples 1 to 10 and Comparative Examples 1 to 12 were evaluated as follows.

[Evaluation item]
(1) Dependence on drive voltage Using a recording head of a Canon inkjet printer (trade name: BJF900), the ejection speed when ejected at four points of drive frequency 5.0 kHz, voltages 14, 15, 16, and 17 V, respectively. Measurement was made to determine ejection stability. The evaluation results are shown in Table 4 below.
A: One point when 8 m / sec or more and B: 8 m / sec or less at all voltages C: Two or more points when 8 m / sec or less (2) Drive frequency responsiveness Drive using the above recording head The discharge was carried out at a frequency of 0.1 kHz, the frequency was gradually increased, and the frequency was measured and judged when the discharge shape became unstable discharge with no main droplet. The evaluation results are shown in Table 4 below.
A: Over 10 kHz B: 5-10 kHz
C: Less than 5 kHz (3) Curling resistance Using an inkjet printer manufactured by Canon Inc. (trade name: BJF900), leaving 1 cm on the top, bottom, left and right of the P4 paper NSK manufactured by Canon Inc. A solid print was performed. The obtained recorded matter was placed in a 25 ° C./55% environment, and the state after one day was observed and visually evaluated. The evaluation criteria are as follows. The evaluation results are shown in Table 4 below.
A: Maintaining a substantially flat state B: End portion is raised C: Tubular (4) Marker resistance A4 size Canon using Canon inkjet printer (trade name: BJF900) A character pattern was printed on PPC paper manufactured by Co., Ltd., and the printed part was traced with a line marker after 1 minute and 1 hour. The evaluation results are shown in Table 4 below.
A: No ink tailing is observed in the printed part after 1 minute and 1 hour B: Ink trailing is seen in the printed part after 1 minute, but not observed after 1 hour C: 1 minute After and after 1 hour, there is ink tailing in the print area

  From the results of the evaluations (1) to (4) in Table 4 above, all of the inks of the present invention in Examples 1 to 8 have good ink jet discharge suitability, curl resistance and marker resistance. Was confirmed.

It is a schematic perspective view which shows the principal part of an example of the inkjet printer which can mount a liquid discharge head. It is a schematic perspective view showing an example of an ink jet cartridge provided with a liquid discharge head.

Claims (11)

  In an inkjet recording ink containing an aqueous medium, a water-insoluble colorant, and a dispersant for dispersing the water-insoluble colorant in the aqueous medium, the inkjet recording ink contains polyglycerin, and the dispersant is hydrophobic An ink for inkjet recording, which is a block polymer comprising a segment, a nonionic hydrophilic segment, and an ionic hydrophilic segment.   The ink for inkjet recording according to claim 1, wherein the dispersant is a triblock polymer having a structure in which a hydrophobic segment, a nonionic hydrophilic segment, and an ionic hydrophilic segment are arranged in this order.   The ink for ink-jet recording according to claim 1 or 2, wherein a polymerization degree ratio of monomers constituting the nonionic hydrophilic segment and the ionic hydrophilic segment is in a range of 20: 1 to 1: 2.   When the polymerization degree ratio of the monomers constituting the hydrophobic segment, the nonionic hydrophilic segment, and the ionic hydrophilic segment is 10, the nonionic hydrophilic segment is 8 or less and the ionic hydrophilic segment is 5 or less. The ink for ink-jet recording according to any one of claims 1 to 3.   The ink for inkjet recording according to any one of claims 1 to 4, wherein the block polymer contains a polyvinyl ether structure as a repeating unit structure.   The ink for inkjet recording according to any one of claims 1 to 5, wherein the polyglycerol is diglycerol. The amount of driving of the ink according to claim 1 is 0.03 to 30 mg / cm ² with respect to a recording medium containing cellulose having a recording area of 15 cm ² or more using an inkjet head. An ink jet recording method comprising a step of recording as a range.   The ink jet recording method according to claim 7, wherein the recording medium containing cellulose is plain paper.   The ink jet recording method according to claim 7, wherein the ink jet head is a thermal ink jet head.   An ink jet recording apparatus comprising: an ink containing portion that contains the ink according to claim 1; and an ink jet head that discharges the ink.   The inkjet recording apparatus according to claim 10, wherein the inkjet head is a thermal inkjet head.

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