JPH101632A - Ink jet recording ink, ink jet recording method and apparatus using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet recording ink which has good print quality, concealing property, and water resistance with respect to plain paper and does not cause bleeding when a color image is formed, an ink jet recording method using the ink, and Provide equipment. SOLUTION: When the pH is changed from an acidic side to an alkaline side at least in an aqueous solution of a coloring material, the colorant has a viscosity peak showing a maximum viscosity, and when the pH is changed from an alkaline side to an acidic side, the viscosity increases. An ink jet recording ink containing a coloring material having a property of increasing viscosity without having a maximum value, a liquid medium dissolving the coloring material, an ink jet recording method and an apparatus using the same.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording ink, an ink jet recording method using such an ink, and an ink jet recording apparatus. More specifically, when forming inks and color images having excellent print quality such as no feathering on various types of plain paper and excellent water resistance, the boundary bleeding in the boundary region between inks of different colors is considered. Ink that does not cause, an inkjet recording method using such an ink,
And an apparatus for inkjet recording.

[0002]

2. Description of the Related Art Ink-jet recording inks of various compositions have hitherto been reported. In particular, in recent years, print quality and water resistance of printed matter when printed on plain paper are required, and in response to this, detailed research and development have been made from various aspects such as ink composition and physical properties.

For example, Japanese Patent Application Laid-Open No. 61-2771 and
JP-A-61-2773 and JP-A-61-2774.
Japanese Patent Application Publication No. JP-A-2003-115122 discloses an ink containing a monoazo dye containing an alkylamine residue or an alkoxyalkylamine residue having 6 to 18 carbon atoms and having good image clarity and storage stability. Japanese Patent Application Laid-Open No. 61-247770 discloses a monoazo dye having good water resistance and light resistance. Further, EP 0 468 647 A1 and EP 0 686 647 A1
468648A1 and EP0468649A1 disclose a dye having a dimer structure of a monoazo dye which may have an alkyl group or a substituted alkyl group, and a gold-containing dye having good water resistance. Also, JP-A-4-35
No. 9066 discloses a disazo dye having good water resistance. In addition, Japanese Patent Publication No. 5-80955 discloses an ink capable of improving the water resistance by adding a long-chain alkyl group as a hydrophobic group to an aqueous dye and adjusting the surface tension of the ink by the structure and the amount of the dye. I have.

Japanese Patent Application Laid-Open No. 2-182470 discloses a method of improving the drying property by using a special surfactant such as an acetylene glycol ethylene oxide adduct in an ink. Japanese Patent Application Laid-Open No. 5-1484 discloses a method in which a dye is precipitated by using an amphoteric surfactant and utilizing the pH of paper after printing to thereby prevent printing bleeding.
Japanese Patent Publication No. 38 discloses an ink or the like which has excellent drying characteristics and print quality, particularly excellent print density by containing an azo dye compound having a specific structure and a phenyl ether compound having a specific structure in the ink.

[0005] Japanese Patent Application Laid-Open No. 6-313138 discloses a method for improving the drying property by using a carboxylic acid ester and preventing the image from deteriorating.

[0006]

However, in the above-described inks, water resistance is not good, and bleeding cannot be suppressed when performing color image recording.
In addition, when used in combination with a penetrant, there is a problem that feathering and bleeding when touching water become severe.

Further, the ink for writing implements such as a ball-point pen disclosed in Japanese Patent Application Laid-Open No. 5-186730 has a direct contact between the pen tip and the recording material during recording, and further applies pressure. It penetrates into the inside of the recording material. In particular, when the recording material in this case is paper, especially plain paper, it can be said that the coloring material is easily dyed on cellulose of the paper. Therefore, print quality, water resistance and fixability can be obtained. The same can be said for thermal transfer printing.

However, in the case of ink jet recording, printing is performed by ejecting ink toward a recording material, so that a pen point or the like is not used at the time of recording, so that there is no direct contact with the recording material. Further, since no pressure is applied, the ink does not enter the inside of the recording material.

Therefore, in particular, in the case of plain paper, the water resistance and the fixing property are poor, and bleeding occurs when recording a color image. For this purpose, a method has been disclosed in which a penetrating agent is contained in the ink to lower the surface tension of the ink and increase the permeability to the recording material. Bleeding occurs due to the penetration of the coloring material, the effect of stopping printing bleeding differs depending on the recording material, such as the surface pH and the type of sizing agent, or a specific trisazo dye was used. Even if an effect such as quick drying is obtained only in the case, there are problems such as a problem in water resistance of the printed matter and a limited dye which can be used for securing storage stability in alkaline. . In addition, there is a problem that bleeding is conspicuous when touching water.

As described above, no ink has yet been found that satisfies the fast drying property, print quality, and water resistance of a printed matter. In particular, no ink has been found which improves the drying property and water resistance by using a penetrant in combination, and at the same time improves the print quality.

Accordingly, an object of the present invention is to provide an ink which has good print quality and water resistance on various plain papers and which does not cause bleeding when forming a color image, an ink jet recording method using such an ink, and an ink jet recording method. An object of the present invention is to provide a recording device.

[0012]

That is, the present invention has a viscosity peak showing a maximum viscosity at least when the pH is changed from an acidic side to an alkaline side at least in an aqueous solution of a coloring material (see FIG. 1). In addition, when the pH is changed from an alkaline side to an acidic side, a color material having a characteristic of increasing the viscosity without having a maximum value (see FIG. 2) and a liquid medium dissolving the color material are contained. An ink for inkjet recording characterized by the following.

The ink for ink jet recording of the present invention is:
When the 3% by weight aqueous solution containing a coloring material at 25 ° C. changes the pH from an acidic side to an alkaline side, an ink having a peak showing a maximum viscosity in a pH range of 6 or more (see FIG. 3) is preferable. Further, when the 3% by weight aqueous solution containing a coloring material at 25 ° C. changes the pH from an alkaline side to an acidic side, thickening starts in a region where the pH is 6 or more (see FIG. 4).
Inks are preferred.

The maximum value of the viscosity of the aqueous solution of the coloring material when the pH is changed from an acidic side to an alkaline side is as follows:
50% in a 3% by weight aqueous solution containing a coloring material at 25 ° C.
Inks having a cps or higher (see FIG. 5) are preferred. The liquid medium for dissolving the coloring material is preferably at least one liquid medium having a surface tension of 40 dyne / cm or less at 25 ° C., for example, an ink containing an organic solvent.

The ink for ink jet recording of the present invention is preferably an ink containing a nitrogen-containing compound. It is preferable that the nitrogen-containing compound is a compound that produces an alkaline compound by hydrolysis, such as urea, thiourea, or a derivative thereof. An ink in which the pH of the ink is more alkaline than the pH value indicating the maximum viscosity when the pH of the aqueous solution of the coloring material is changed from an acidic side to an alkaline side.

According to a second aspect of the present invention, there is provided an ink jet recording method for performing recording on a recording material by discharging ink droplets from an orifice in accordance with a recording signal.
The aqueous solution of the coloring material has a peak showing a maximum viscosity at least when the pH is changed from an acidic side to an alkaline side (see FIG. 1), and when the pH is changed from an alkaline side to an acidic side, the viscosity becomes lower. Thickens without a maximum (see Figure 2)
An ink jet recording method comprising an ink containing a coloring material having characteristics and a liquid medium dissolving the coloring material.

According to a third aspect of the present invention, there is provided a recording unit including an ink storing section for storing ink and a head section for discharging the ink as ink droplets, wherein the aqueous solution of the coloring material is at least pH When the pH was changed from an acidic side to an alkaline side, it had a peak showing the maximum viscosity (see FIG. 1), and when the pH was changed from an alkaline side to an acidic side, the viscosity increased without having a maximum value. A recording unit comprising an ink containing a coloring material having a sticking property (see FIG. 2) and a liquid medium dissolving the coloring material. A recording unit in which the ink container is formed of polyurethane, cellulose, or polyvinyl acetate is preferable.

According to a fourth aspect of the present invention, there is provided an ink cartridge provided with an ink storing section for storing ink, wherein an aqueous solution of a coloring material is used when the pH is changed from an acidic side to an alkaline side at least. A coloring material having a peak indicating viscosity (see FIG. 1) and having a property of increasing the viscosity without having a maximum value when the pH is changed from an alkaline side to an acidic side (see FIG. 2); An ink cartridge comprising an ink containing a liquid medium for dissolving the coloring material. An ink cartridge in which the ink container has a liquid contact surface formed of polyolefin is preferable.

According to a fifth aspect of the present invention, there is provided an ink jet recording apparatus comprising: a recording unit having an ink storing section for storing ink and a head for discharging the ink as ink droplets, wherein the ink comprises a color material. Has a peak showing the maximum viscosity at least when the pH is changed from an acidic side to an alkaline side (see FIG. 1), and when the pH is changed from an alkaline side to an acidic side, the viscosity has a maximum value. An ink jet recording apparatus comprising an ink containing a color material having a property of increasing the viscosity (see FIG. 2) without having a color medium and a liquid medium dissolving the color material. An ink jet recording apparatus in which the ink container is formed of polyurethane, cellulose, or polyvinyl acetate is preferable.

According to a sixth aspect of the present invention, there is provided a recording head for ejecting ink droplets, an ink cartridge having an ink containing section containing ink, and an ink supply section for supplying ink from the ink cartridge to the recording head. Wherein the aqueous solution of the coloring material of the ink has a peak showing the maximum viscosity at least when the pH is changed from an acidic side to an alkaline side (see FIG. 1), and the pH is adjusted to an alkaline side. When changed from acidic to acidic, the viscosity increases without having a maximum value (see FIG. 2).
An ink jet recording apparatus comprising an ink containing a coloring material having characteristics and a liquid medium dissolving the coloring material. An ink jet recording apparatus in which the ink container has a liquid contact surface made of polyolefin is preferable.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The ink jet recording ink of the present invention has a peak showing a maximum viscosity at least when the pH is changed from an acidic side to an alkaline side at least in an aqueous solution of a coloring material (see FIG. 1). It is characterized by containing a coloring material having a characteristic that the viscosity increases without changing the viscosity from an alkaline side to an acidic side without a maximum value (see FIG. 2), and a liquid medium for dissolving the coloring material.

According to the present invention, as a result of diligent studies on the ink composition having good print quality and water resistance of the print recorded matter using the ink for ink jet recording, the pH was changed from the acidic side to the alkaline side in the aqueous solution of the coloring material. When the pH is changed from an alkaline side to an acidic side, the viscosity increases without a maximum value (see FIG. 2). It has been found that, in the case of an ink jet recording ink using a coloring material, print quality and water resistance are improved.

The reason why the above object is achieved by the present invention is considered as follows. When a liquid medium having a surface tension of 40 dyne / cm or less at 25 ° C. is used, first, the behavior of the viscosity when the pH of the colorant-containing aqueous solution is changed from the acidic side to the alkaline side, and the pH is changed from the alkaline side to the acidic side. The behavior of the viscosity when changed should show the behavior of the pH and the viscosity of the ink containing the coloring material.

Then, the ink lands on the recording material, and the pH of the ink is lowered by the pH of the recording material. In the process, the viscosity of the ink greatly increases, and the components of the dye in the recording material and the recording material are reduced. Are considered to be combined, and the force of bleeding along the fiber can be suppressed, so that feathering does not occur, and the image is sharp and the fixability is considered to be good. Further, since the fluidity of the ink is reduced by the increase in the viscosity, the water resistance is also improved. Further, even when a color image is recorded, bleeding does not occur. Further, when two adjacent colors at the time of recording a color image are both inks of the present invention, bleeding does not occur at all. That is, p of the recording material
When an ink having a property of greatly increasing the viscosity in a region more alkaline than H is used, bleeding or the like is suppressed.

The surface tension at 25 ° C. is 40 dy.
When a liquid medium of ne / cm or less is used, it is considered that the pH of the ink is lowered by the pH of the recording material while the ink permeates the recording material, and the above-described action is performed.

Similarly, even if the ejected ink lands on the recording material and then comes into contact with water or other liquid having a pH higher than the pH of the ink, the pH changes from the acidic side to the alkaline side.
When the color is changed, the use of a coloring material having a property of increasing viscosity suppresses bleeding and improves water resistance.

Another is that the pH of the aqueous solution of the coloring material is adjusted to pH.
Has a peak showing the maximum viscosity when is changed from an acidic side to an alkaline side (see FIG. 1), and when the pH is changed from an alkaline side to an acidic side, the viscosity increases without having a maximum value. When the recording material is plain paper, the ink containing the coloring material having the characteristic (see FIG. 2) will penetrate into the paper together with the liquid medium having a surface tension of 40 dyne / cm or less at 25 ° C. However, since the coloring material has a strong power of dyeing with cellulose of paper, after dyeing with cellulose, it is pulled by the liquid medium which is going to further penetrate, and does not start to bleed along the fibers of the paper. Also, even if it comes into contact with water, it does not flow with water or other liquid media.

Therefore, it is considered that the bleeding is suppressed, the print quality is good, the water resistance is good, and the bleeding during color image recording is also good. Therefore, the effect of the coloring material having the above-described characteristics is remarkably exhibited in the water resistance before the liquid medium in which the coloring material is dissolved immediately after printing is not volatilized from the paper surface. Here, the liquid medium has a surface tension of 40 dyne / c at 25 ° C.
If the liquid medium of m or less is not contained, the effect of dyeing with cellulose as described above is weakened.

More specifically, a 3% by weight aqueous solution containing a coloring material at 25 ° C. has a peak showing a maximum viscosity in a pH range of 6 or more when the pH is changed from an acidic side to an alkaline side (see FIG. 3). In addition, when the pH is changed from an alkaline side to an acidic side, thickening starts in a region of pH 6 or higher, and the ink is thickened without having a maximum value (see FIG. 4). Is the case. More specifically, 25
In the case of an ink using a coloring material having a maximum viscosity of 50 cps or more (see FIG. 5) when the pH is changed from an acidic side to an alkaline side in a 3% by weight coloring material-containing aqueous solution at ° C. Examples of such coloring materials include monomers or dimers having an azo structure containing at least a carboxyl group, and those having a linear structure or a cyclic compound having 4 or more carbon atoms.

In the case of a coloring material having a linear structure or a cyclic compound having 4 or more carbon atoms as described above, the length of an alkyl group sufficient to generate a hydrogen bond within a coloring material molecule or between coloring material molecules. It is considered that the viscosity increases due to the hydrogen bond generated there.

However, in a 3% by weight aqueous solution containing a coloring material at 25 ° C., when the pH is changed from an acidic side to an alkaline side, the viscosity does not increase in the pH range of 6 or more (see FIG. 6). When the pH is changed from an alkaline side to an acidic side, in the case of an ink using a color material that does not start thickening in a region of pH 6 or more (see FIG. 7 or 8), the acidity is higher than the pH of the recording material. Since the thickening or no thickening in the side area, it is not possible to suppress the feathering and bleeding described above, the water resistance is also reduced, and when forming a color image, bleeding will occur Conceivable.

Further, when the pH was changed from an acidic side to an alkaline side in a 3% by weight aqueous solution containing a coloring material at 25 ° C., the viscosity did not increase in the pH range of 6 or more (see FIG. 6). When the color is changed from an alkaline side to an acidic side, the viscosity does not start in the region of pH 6 or more (see FIG. 7 or 8), and the color material having the viscosity characteristics shown in FIGS. It was also found that the use of a combination improves the concealability of the printed matter.

More preferably, 3% by weight at 25 ° C.
In the colorant-containing aqueous solution, when the pH is changed from an acidic side to an alkaline side, the viscosity does not increase (see FIG. 6), and when the pH is changed from the alkaline side to the acidic side, the pH is less than 6. Is a color material having the property of starting to thicken in the region of No. and increasing without having a maximum value (see FIG. 7).

The reason for this is that if the aqueous solution of the coloring material is only the coloring material that increases in the pH range higher than the pH of the recording material,
Since there is no bleeding or spread between dots, non-uniform printing may occur in the case of solid printing, but coloring materials that do not increase in viscosity at pH 6 or higher in aqueous coloring material solutions are also included. If so, the thickening starts at the time when the bleeding starts slightly, so that the unevenness of the solid portion is considered to be eliminated. Here, when the pH of the aqueous solution of the coloring material is not changed even when the pH is changed from the acidic side to the alkaline side or when the pH is changed from the alkaline side to the acidic side (see FIGS. 6 and 8), the coloring material is used. In some cases, bleeding and water resistance may be a problem. However, when the pH was changed from the acidic side to the alkaline side at 25 ° C. in the aqueous solution containing 3% by weight of the colorant without increasing the viscosity (see FIG. 6), the pH was changed to 6 from the alkaline side to the acidic side. When thickening starts in a region of less than and has a maximum value and does not have a maximum value (see FIG. 7), when mixed with a coloring material, a thickening effect of ink occurs after landing on a recording material, so that printing quality is reduced. It is considered that water resistance, bleeding at the time of recording a color image, and hiding properties are improved.

Furthermore, the inclusion of a nitrogen-containing compound further enhances the solubility of the dye, and furthermore has the effect of preventing clogging and sticking at the nozzle tip in ink-jet recording in order to maintain the solubility stability of the dye. I found it.

Next, the present invention will be described in more detail with reference to preferred embodiments. The coloring material used in the present invention has a viscosity peak showing the maximum viscosity at least when the pH is changed from an acidic side to an alkaline side in an aqueous solution of the coloring material (see FIG. 1). When the color is changed from the side to the acid side, a dye having a property that the viscosity increases without having a maximum value (see FIG. 2) is used. Preferably, when the pH is changed from an acidic side to an alkaline side in a 3% by weight aqueous solution containing a coloring material at 25 ° C., p
The maximum viscosity has a peak of 50 cps or more in the region of H6 or more (see FIG. 5). Then, when the pH is changed from the alkaline side to the acidic side, the thickening starts in the region of pH 6 or more and increases without having a maximum value. Colorants that are sticky (see FIG. 4) are preferred.

Further, it is preferable that the monomer or dimer having at least a carboxyl group and having an azo structure. Among these, a coloring material having a straight-chain structure or a cyclic compound having 4 or more carbon atoms is particularly preferable, and the following structural formulas (a) to (a) are attached to both ends of the coloring material structure or the bonding portion of the dimer. A coloring material containing a unit represented by d) and having at least one structural formula (c) or (d), but is not limited thereto.

[0038]

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(In the formula, A is a divalent or trivalent linking group, R is a linear or cyclic compound having 4 or more carbon atoms, and L is an integer of 1 to 3.)

Preferred specific examples of the coloring material containing the unit represented by the above structural formula used in the present invention are shown below.

[0041]

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[0042]

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[0043]

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[0044]

Embedded image Particularly preferred among the exemplified compounds are exemplified compounds 6 to
It is 11.

The content of the coloring material in the ink of the present invention is preferably in the range of 0.2 to 10% by weight, more preferably in the range of 0.5 to 5.0% by weight based on the total weight of the ink. desirable.

As the liquid medium for dissolving at least one coloring material having a surface tension of 40 dyne / cm or less at 25 ° C. and used in the present invention, a nonionic surfactant is preferable. Adducts are preferred. Among them, ethylene oxide adducts of higher alcohols, ethylene oxide adducts of alkylphenols, ethylene oxide-propylene oxide copolymers, and ethylene oxide adducts of acetylene glycol are preferred. Particularly preferred is an ethylene oxide adduct of acetylene glycol. Further, the number of moles of ethylene oxide added is preferably in the range of 4 to 20.

The surface tension is 40 dyn at 25 ° C.
Specific examples of preferred compounds of the liquid medium that dissolves at least one coloring material having an e / cm or less are shown below.

[0048]

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The surface tension is 40 dyn at 25 ° C.
e / cm or less, the content of the liquid medium for dissolving at least one colorant is 0.01 to 1 with respect to the total weight of the ink.
A range of 0.0% by weight is preferred. If it is less than 0.01% by weight, the desired permeability cannot be generally obtained depending on the kind,
If the amount exceeds 0.0% by weight, the initial viscosity of the ink becomes large, and the ejection tends to become unstable, which is not preferable.
More preferably, it is in the range of 0.1 to 5.0% by weight.

Of the liquid medium for dissolving the colorant used in the present invention, the surface tension is 40 dyne / cm at 25 ° C.
Other liquid media that dissolve the colorant, which may not be the following, include, for example, amides such as dimethylformamide and dimethylacetamide; ketones such as acetone; ethers such as tetrahydrafuran and dioxane; polyethylene glycol; Polyalkylene glycols such as polypropylene glycol; 2 to 6 alkylene groups such as ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene glycol and diethylene glycol; Alkylene glycols containing a carbon atom; glycerin; ethylene glycol monomethyl (or ethyl) ether, diethylene glycol monomethyl (or ethyl) ether, triethylene glycol monomethyl ( Lower alkyl ethers of polyhydric alcohols such as ethyl) ether; ethanol, monovalent alcohols such as isopropyl alcohol; N- methyl -
2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, sulfolane, dimethylsulfoxide, 2-
Cyclic amide compounds such as pyrrolidone and ε-caprolactam; and imide compounds such as succinimide.
However, it is not limited to these compounds.

The content of the other liquid medium for dissolving the coloring material is generally preferably from 10 to 40% by weight, more preferably from 10 to 30% by weight, based on the total weight of the ink.

The content of water in the ink is 40 to 8
It is used in the range of 9.8% by weight. If the amount is less than 40% by weight, the viscosity of the ink increases, which is not preferable. On the other hand, if it exceeds 89.8% by weight, the reliability cannot be satisfied.

Further, in the 3% by weight aqueous solution containing a coloring material at 25 ° C. used in the present invention together with the coloring material, p
When H is changed from an acidic side to an alkaline side, it does not thicken in a region of pH 6 or more (see FIG. 6), and when H is changed from an alkaline side to an acidic side, it thickens in a region of pH 6 or more. (See FIG. 7 or 8) is a color material in which the pH is changed from an acidic side to an alkaline side in a 3% by weight aqueous solution containing a color material at 25 ° C.
When the pH is changed from an alkaline side to an acidic side without increasing the viscosity in a region of 6 or more (FIG. 6), the viscosity starts increasing in a region of less than pH 6 and increases without having a maximum value. (See FIG. 7) is preferred. Further, it is preferably a monomer or a dimer having an azo structure containing at least a carboxyl group.

Of these, it is particularly preferable that the terminal of the coloring material structure or the bonding portion of the dimer be represented by the following structural formulas (e) to (e).
A coloring material containing a unit represented by (i) and at least one unit represented by structural formula (g), (h) or (i), but is not limited thereto. Absent.

[0055]

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(Wherein X is an alkyl group having 4 or more carbon atoms;
A represents a divalent or trivalent linking group, and L represents an integer of 1 to 3. )

Specific examples of preferred compounds containing the units represented by the above structural formulas (e) to (i) are shown below.

[0058]

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[0059]

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[0060]

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[0061]

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Among the above exemplified compounds, particularly preferred are exemplified compounds 18 to 23. The mixing ratio of the dyes represented by the exemplified compounds 1 to 11 and the dyes represented by the exemplified compounds 13 to 25 is 1: 0.1 to 1:10, preferably 1: 0.1 to 1: 1. : 5, more preferably 1: 0.1
１1: 1. 1: Exemplified compound 1 than 0.1
Exemplified compounds 13 to 23 when the dyes represented by
The effect of the dye represented by etc. does not appear, and the concealing property of the printed matter may be deteriorated, and the printed matter is easily oozed when the dye represented by the exemplified compounds 13 to 23 is more than 1:10 Problems such as poor water resistance.

Examples of the nitrogen-containing compound used in the present invention include, but are not limited to, urea, thiourea, ethylene urea, alkyl urea, alkyl thiourea, dialkyl urea, and dialkyl thiourea. It is particularly preferable to use urea or thiourea or a derivative thereof.

The content of the nitrogen-containing compound is preferably in the range of 1.0 to 10.0% by weight based on the total weight of the ink.

In addition to the above components, the ink of the present invention may further contain additives such as a preservative, an antioxidant, an evaporation promoter, a rust inhibitor, a fungicide, and a chelating agent. It does not matter.

The pH of the ink of the present invention may be more alkaline than the pH of the coloring material showing the maximum value when the pH of the aqueous solution of the coloring material is changed from the acidic side to the alkaline side. Is a value that is 1.0 alkaline side of the pH value indicating the maximum viscosity of the coloring material.

Suitable methods and apparatuses for performing recording using the ink of the present invention include an ink jet recording method in which ink droplets are ejected from an orifice according to a recording signal, and an ink jet recording apparatus. An ink jet recording method and an ink jet recording apparatus in which thermal energy corresponding to a recording signal is applied to ink in a room, and droplets are ejected by the thermal energy.

FIGS. 9, 10 and 11 show examples of the structure of a head which is a main part of the apparatus. The head 13 is formed by bonding a glass, ceramic or plastic plate having a groove 14 through which ink passes to a heating head 15 (a head is shown in the figure, but is not limited to this) used for thermal recording. Is obtained. The heating head 15 includes a protective film 16 made of silicon oxide or the like, and an aluminum electrode 17.
-1 and 17-2, heat generating resistor layer 18 made of nichrome or the like, heat storage layer 19, substrate 2 having good heat dissipation such as alumina
Consists of zero.

The ink 21 has a discharge orifice (fine hole) 2
The meniscus 23 is formed by a pressure (not shown). Now, when an electric signal is applied to the electrodes 17-1 and 17-2, the area of the heating head 15 indicated by n rapidly generates heat, and bubbles are generated in the ink 21 in contact with the area.
The meniscus 23 is protruded by the pressure, the ink 21 is ejected, becomes a recording droplet 24 from the orifice 22, and flies toward the recording material 25.

FIG. 11 is an external view of a multi-head in which many heads shown in FIG. 9 are arranged. The multi-head is manufactured by closely contacting a glass plate 27 having a multi-groove 26 and a heating head 28 similar to that described with reference to FIG. Note that FIG.
FIG. 10 is a cross-sectional view of the head 13 along the ink flow path, and FIG. 10 is a cross-sectional view taken along line AB in FIG.

FIG. 12 shows an example of an ink jet recording apparatus incorporating such a head. In FIG.
1 is a blade as a wiping member, one end of which is held by a blade holding member to become a fixed end,
It takes the form of a cantilever. The blade 61 is provided at a position adjacent to a recording area of the recording head.

In the case of this example, the recording head is held in a form protruding into the moving path of the recording head. 62 is a cap,
It is arranged at the home position adjacent to the blade 61,
The recording head is configured to move in a direction perpendicular to the direction of movement of the recording head, contact the ejection port surface, and perform capping. 6 more
Reference numeral 3 denotes an ink absorber disposed adjacent to the blade 61, and is held in a form protruding into the movement path of the recording head, similarly to the blade 61. The blade 61, the cap 62, and the ink absorber 63 constitute an ejection recovery unit 64, and the blade 61 and the ink absorber 63 remove moisture, dust, and the like from the ink ejection port surface.

Reference numeral 65 denotes a recording head which has discharge energy generating means and discharges ink onto a recording material opposed to the discharge port surface provided with discharge ports to perform recording. And a carriage for moving the recording head 65. The carriage 66 is slidably engaged with the guide shaft 67, and a part of the carriage 66 is connected to a belt 69 driven by a motor 68 (not shown).
As a result, the carriage 66 can move along the guide shaft 67, and the recording head 65 can move the recording area and the adjacent area.

Reference numeral 51 denotes a paper feed unit for inserting a recording material, and reference numeral 52 denotes a paper feed roller driven by a motor (not shown). With such a configuration, the recording material is fed to a position facing the ejection port surface of the recording head, and is discharged to a discharge section provided with a discharge roller 53 as recording proceeds.

In the above configuration, when the recording head 65 returns to the home position at the end of recording or the like, the head recovery unit 6
The cap 62 of 4 is retracted from the moving path of the recording head 65, but the blade 61 protrudes into the moving path. As a result, the ejection port surface of the recording head 65 is wiped. When capping is performed with the cap 62 in contact with the ejection surface of the recording head 65, the cap 62 moves so as to protrude into the movement path of the recording head.

When the recording head 65 moves from the home position to the recording start position, the cap 62 and the blade 61 are at the same position as the position at the time of wiping. As a result, even in this movement, the ejection port surface of the recording head 65 is wiped.

The movement of the print head to the home position is performed not only at the end of printing and at the time of ejection recovery, but also at a predetermined interval while the printing head moves through the printing area for printing. Position, and the wiping is performed along with the movement.

FIG. 13 is a view showing an example of an ink cartridge containing ink supplied to the head via an ink supply member, for example, a tube. Here, reference numeral 40 denotes an ink storage portion that stores the supply ink, for example, an ink bag, and a rubber stopper 42 is provided at the tip thereof. By inserting a needle (not shown) into this stopper 42,
The ink in the ink bag 40 can be supplied to the head. An ink absorber 44 receives the waste ink. It is preferable for the present invention that the ink container has a liquid contact surface made of polyolefin, particularly polyethylene.

The ink jet recording apparatus used in the present invention is not limited to the one in which the head and the ink cartridge are separated from each other as described above, but is also suitable for the one in which they are integrated as shown in FIG. Used.

In FIG. 14, reference numeral 70 denotes a recording unit, in which an ink container containing ink, for example, an ink absorber is stored, and the ink in the ink absorber has a plurality of orifices. Head part 71
Are ejected as ink droplets from the ink. As the material of the ink absorber, it is preferable for the present invention to use polyurethane, cellulose or polyvinyl acetate.

Reference numeral 72 denotes an atmosphere communication port for communicating the inside of the recording unit with the atmosphere. This recording unit 70
It is used in place of the recording head shown in FIG. 12, and is detachable from the carriage 66.

In FIG. 15, reference numeral 100 denotes a recording head element, which is an ink ejection section 102, an ink supply tank section 104, a wiring board 105 provided with a wiring for transmitting a signal for driving an ejection energy generating element, and a support for these. And the like. The ink ejection unit 102 includes an ejection port 1 formed on a surface facing the recording medium.
02A, a liquid passage extending inward thereof, a discharge energy generating element such as an electrothermal converter disposed in each liquid passage, and a common liquid chamber communicating with each liquid passage. The ink supply tank unit 104 functions as a sub-tank that receives ink supply from the ink tank 110 side and guides the ink to a common liquid chamber in the ejection unit 102.

The base plate 106 can be made of aluminum or the like, and also functions as a heat radiating plate for suppressing heat generation of the recording head element due to driving of the electrothermal transducer. Reference numeral 112 denotes an ink absorber provided in the ink tank 110 and impregnated with ink, and can be formed using a porous body or a fiber made of the above-described material. Reference numeral 114 denotes a lid member of the ink tank 110. Reference numeral 107 denotes a protrusion provided on the recording head element 100,
A taper is provided to facilitate the connection with 10. Reference numeral 117 denotes an element storage unit 1 of the ink tank 110.
The opening provided in the wall portion 117A of the projection 10A.
7, the recording head element 10
0 and the ink tank 110 are connected.

Reference numeral 118 denotes an abutment member provided in the element accommodating portion 110A for facilitating the work of mounting the recording head element 100 and ensuring the mounting state, and is engaged with the rear end face of the base plate 106.
Reference numeral 119 denotes a projection for positioning the print head element 100, and reference numeral 120 denotes a supply port for supplying ink from the ink tank 110 into the print head element 100.

In the recording apparatus used in the present invention,
In the above description, an ink jet recording apparatus that ejects ink droplets by applying thermal energy to ink has been described. However, the present invention can be similarly applied to other ink jet recording apparatuses such as a piezo method using a piezoelectric element.

[0086]

Next, the present invention will be described more specifically with reference to examples and comparative examples. In the following description, parts and%
Unless otherwise specified, the values are based on weight.

Further, in a 3% by weight aqueous dye solution at 25 ° C., even if the pH is changed from an alkaline side to an acidic side or from an acidic side to an alkaline side, the coloring material does not increase in viscosity at all. The following exemplary compounds are shown as (see FIGS. 6 and 8).

[0088]

Embedded image With respect to the coloring material having a form other than the acid type, acid precipitation was performed to obtain an acid type coloring material.

Examples 1 to 14 After the following components were mixed and dissolved, the pore size was adjusted to 0.1.
Pressure filtration was performed using a 22 μm membrane filter (trade name: Fluoropore Filter, manufactured by Sumitomo Electric Industries, Ltd.) to prepare the inks of the present examples.

Note that each ink is p
H is 1.0 alkaline side from the pH value indicating the maximum viscosity when the pH of each coloring material is changed from an acidic side to an alkaline side.
Adjusted to 9.5. In addition, the display of the figure in the parenthesis of an example compound shows the behavior by the pH change of the example compound.

Ink Composition Exemplified Compound 1 of Example 1 (see FIGS. 5 and 4) 3 parts 1,2,3-hexanetriol 10 parts Thiodiglycol 5 parts Water 82 parts

Ink composition of Example 2 Exemplified compound 3 (see FIGS. 5 and 4) 4 parts Glycerin 5 parts Polyethylene glycol 10 parts Exemplified compound 12 (m + n = 8) 0.2 parts Water 80.8 parts

Ink composition of Example 3 Exemplified compound 4 (see FIGS. 5 and 4) 3 parts Hexylene glycol 8 parts Diethylene glycol 7 parts Exemplified compound 12 (m + n = 12) 0.1 parts Urea 7 parts Water 74.9 parts

Ink Composition of Example 4 Exemplified Compound 1 of Example 1 was replaced with Exemplified Compound 6 (FIGS. 5 and 4).
Ink composition of Example 5 Example compound 3 of Example 2 was replaced with Example compound 8 (FIGS. 5 and 4)
Ink composition of Example 6 Example compound 4 of Example 3 was replaced with Example compound 11 (see FIGS. 5 and 4)

Ink composition of Example 7 Exemplified compound 2 (see FIGS. 5 and 4) 1 part Exemplified compound 24 (see FIGS. 6 and 8) 2 parts Triethylene glycol 8 parts Ethanol 5 parts Water 84 parts

Ink Composition Exemplified Compound 5 of Example 8 (see FIGS. 5 and 4) 1.5 parts I. Acid Red 133 (shows the behavior of FIGS. 6 and 8) 1.5 parts Butylene glycol 10 parts 2-Pyrrolidone 6 parts Exemplified compound 12 (m + n = 12) 0.2 parts Water 80.8 parts

Compound 9 of ink composition of Example 9 (see FIGS. 5 and 4) 1.5 parts I. Direct Yellow 86 (showing the behavior of FIGS. 6 and 8) 1.5 parts Glycerin 9 parts Thiodiglycol 7 parts Exemplary compound 12 (m + n = 10) 0.2 parts Urea 5 parts Water 75.5 parts

Ink Composition of Example 10 Example Compound 2 of Example 7 was replaced with Example Compound 7 (FIGS. 5 and 4).
Ink composition of Example 11 Ink composition of Example 11 Ingredient 5 is replaced with Exemplified compound 10 (see FIGS. 5 and 4) Ink composition of Example 12 Exemplified compound 3 of Example 9 9 (FIGS. 5 and 4)
Reference)

Example 13 Ink Composition of Example 13 Example Compound 14 was obtained by replacing Example Compound 24 of Example 7 with Example Compound 13 (see FIGS. 6 and 7). I. Acid Red 133 was replaced with Exemplified Compound 17 (see FIGS. 6 and 7). Ink Composition of Example 15 C.I. I. Direct Yellow 86 replaced with Exemplified Compound 15 (see FIGS. 6 and 7)

Ink composition of Example 16 Example compound 24 of Example 10 was replaced with Example compound 19 (see FIGS. 6 and 7). Ink composition of Example 17 Example compound 26 of Example 11 was replaced with Example compound 23 (see FIG. 6). 6 and 7) Ink composition of Example 18 C.I. I. Direct Yellow 86 replaced with Exemplified Compound 21 (see FIGS. 6 and 7)

Comparative Examples 1 to 6 In the compositions of Examples 1, 2, 3, 7, 8, and 15, each of the coloring materials was replaced with the following coloring materials, to thereby obtain Comparative Examples 1 to 6, respectively.

Ink Composition of Comparative Example 1 Exemplified Compound 1 of Example 1 was replaced with Exemplified Compound 24 (see FIGS. 6 and 8). Ink Composition of Comparative Example 2 Exemplified Compound 3 of Ex. 6 and 7)

Ink Composition of Comparative Example 3 Example Compound 4 of Example 3 was replaced with Example Compound 22 (see FIGS. 6 and 7) Ink Composition of Comparative Example 4 Example Compound 2 of Example 7 was replaced with Example Compound 14 (see FIG. 6). 6 and 7)

[0104] Comparative Example Exemplified Compound 5 Example Compound 16 of the fifth ink Example 8 Exemplified Compound 3 Example Compound of the ink composition in Example 15 of Comparative Example 6 are replaced (see FIGS. 6 and 7) 15 (FIG. 6 and 7)

Next, using the inks and ink sets of Examples 1 to 18 and Comparative Examples 1 to 6 obtained above, an on-demand type ink jet printer using a heating element as an ink ejection energy source as an ink jet recording apparatus And (2) evaluation of water resistance, (3) evaluation of opacity, and (4) bleeding in a boundary area between inks of different colors in a color image. Evaluation and (5) Evaluation of the re-ejectability of the ink after the printing was stopped were performed according to the following criteria.

Tables 1 and 2 show the obtained results. The following two plain papers were used for the evaluation.
Canon PB paper, Xerox 4024 paper

(Evaluation Method and Evaluation Criteria) (1) Evaluation of Print Quality A predetermined ink is filled in a printer, alphanumeric characters are printed on the two plain papers, and the presence or absence of feathering and the sharpness of characters are determined. Evaluation was performed under a microscope and the naked eye. A: There is no feathering and the characters are sharp. ：: Feathering occurs very slightly, but the characters are sharp. Δ: Feathering slightly occurred, but the characters were sharp. ×: Many feathering and no sharpness in characters.

(2) Evaluation of water resistance-1 A predetermined ink was filled in a printer, alphanumeric characters and a solid portion were printed on the two plain papers, and after stopping printing, leaving for one hour or more, the printing density was reduced. Macbeth RD915 (trade name:
Macbeth). Thereafter, the printed matter was immersed in a container filled with water for 5 minutes, then left to stand, dried, and the print density was measured again, the residual ratio of the printed matter density was obtained, and the water resistance was evaluated.

[0109]

(Equation 1) ：: Remaining rate of printed matter density is 80% or more △: Remaining rate of printed matter density is 66% or more and less than 80% ×: Remaining rate of printed matter density is less than 66%

Evaluation of Water Resistance-2 Immediately after the printer was filled with a predetermined ink and alphanumeric characters and solid portions were printed on the two plain papers, the printed matter was immersed in water for 3 seconds and then pulled out. The printed matter was allowed to stand, dried, and evaluated for the degree of background soiling and bleeding of printed matter. A: Neither dirt nor bleeding is observed. ：: No background dirt is observed, but bleeding is slightly observed. Δ: Soil is slightly seen and bleeding is observed. ×: Both dirt and bleeding are conspicuous.

(3) Evaluation of Concealment Property A predetermined ink was filled in a printer, a solid portion was printed on the two plain papers, and the concealment property of the solid image was evaluated. ：: Good hiding power and high density. Δ: A non-uniform part is slightly observed in the solid part. X: The solid part is uneven and the density is low.

(4) Evaluation of Bleeding in Boundary Regions of Inks of Different Colors in Color Image Ink jet printer BJC600 (trade name: manufactured by Canon Inc.) was used to replace the inks with the inks of Examples and Comparative Examples, respectively. The bleeding in the boundary region between the ink and the ink having a different color tone was evaluated. A: There is no bleeding in a boundary region of a different color tone. ：: Slight bleeding is observed in the boundary areas of different colors. Δ: Bleeding in boundary regions of different colors was observed. ×: Bleeding is noticeable in the boundary areas of different colors.

(5) Evaluation of re-ejectability of ink after printing is suspended Leave it in a thermo-hygrostat at 15 ° C./10% for one hour, then discharge ink droplets from a certain nozzle and use the nozzle for one minute. Next, the ejection stability when the ink droplet was ejected from the nozzle was evaluated. ：: Normal printing can be performed. Δ: Although printing is slightly disturbed, printing can be performed without any problem in actual use. X: Non-discharge or printing disorder.

[0114]

[Table 1]

[0115]

[Table 2]

[0116]

As described above, the ink of the present invention has
By using the ink set, the ink jet recording method, and the ink jet recording apparatus, the print quality such as feathering does not deteriorate for various plain papers, the water resistance is improved, and also when a color image is formed. Bleeding can be prevented.

[Brief description of the drawings]

FIG. 1 is a graph showing a relationship between a change in pH and a change in viscosity of a coloring material.

FIG. 2 is a graph showing a relationship between a pH change and a viscosity change of a coloring material.

FIG. 3 is a graph showing a relationship between a change in pH and a change in viscosity of a coloring material.

FIG. 4 is a graph showing a relationship between a pH change and a viscosity change of a coloring material.

FIG. 5 is a graph showing a relationship between a change in pH and a change in viscosity of a coloring material.

FIG. 6 is a graph showing a relationship between a change in pH and a change in viscosity of a coloring material.

FIG. 7 is a graph showing a relationship between a change in pH and a change in viscosity of a coloring material.

FIG. 8 is a graph showing a relationship between a change in pH and a change in viscosity of a coloring material.

FIG. 9 is a longitudinal sectional view of a head section of the ink jet recording apparatus.

FIG. 10 is a cross-sectional view of a head section of the ink jet recording apparatus.

11 is an external perspective view of a head obtained by multiplying the head shown in FIG. 9;

FIG. 12 is a perspective view illustrating an example of an ink jet recording apparatus.

FIG. 13 is a longitudinal sectional view of the ink cartridge.

FIG. 14 is a perspective view of a recording unit.

FIG. 15 is an exploded perspective view of the recording unit.

DESCRIPTION OF SYMBOLS 13 Head 14 Groove 15 Heating head 16 Protective film 17-1, 17-2 Aluminum electrode 18 Heating resistor layer 19 Heat storage layer 20 Substrate 21 Ink 22 Discharge orifice 23 Meniscus 24 Recording droplet 25 Recording material 26 Multi-groove 27 Glass plate 28 Heating head 40 Ink storage unit 42 Plug 44 Ink absorber 45 Ink cartridge 51 Paper supply unit 52 Paper feed roller 53 Discharge roller 61 Blade 62 Cap 63 Ink absorber 64 Discharge recovery unit 65 Recording head 66 Carriage 70 recording unit 71 head 72 air communication port

Claims (28)

[Claims] Claims: 1. An aqueous solution of a coloring material has a viscosity peak showing a maximum viscosity when the pH is changed from an acidic side to an alkaline side at least, and the viscosity is changed when the pH is changed from an alkaline side to an acidic side. An ink for ink-jet recording comprising: a coloring material having a property of increasing the viscosity without having a maximum value, and a liquid medium dissolving the coloring material. 2. The ink according to claim 1, wherein the coloring material has a peak showing a maximum viscosity in a pH range of 6 or more when the pH of the coloring material aqueous solution is changed from an acidic side to an alkaline side. 3. The method according to claim 1, wherein when the pH of the coloring material is changed from an alkaline side to an acidic side in a 3% by weight aqueous solution containing the coloring material at 25 ° C., the viscosity starts to increase in a pH range of 6 or more. Ink. 4. The maximum value of the viscosity of the coloring material when the pH is changed from an acidic side to an alkaline side is 50 cps or more in a 3% by weight aqueous solution containing the coloring material at 25 ° C. 3. The ink according to 2. 5. A liquid medium for dissolving the colorant, wherein at least one kind of liquid has a surface tension of 40 dyne / cm at 25 ° C.
The ink according to claim 1, comprising the following liquid medium. 6. The surface tension is 40 dy at 25 ° C.
The ink according to claim 5, wherein the liquid medium of ne / cm or less is an organic solvent. 7. The ink according to claim 1, further comprising a nitrogen-containing compound. 8. The ink according to claim 7, wherein the nitrogen-containing compound is a compound that generates an alkaline compound by hydrolysis. 9. The ink according to claim 7, wherein the nitrogen-containing compound is urea, thiourea, or a derivative thereof. 10. The pH of an ink is adjusted to the pH of an aqueous solution of a coloring material.
2. The ink according to claim 1, wherein the pH of the ink is more alkaline than the pH value indicating the maximum viscosity when the pH is changed from an acidic side to an alkaline side. 11. The ink according to claim 1, wherein at least one of the counter ions of the coloring material is ammonia or an alkylamine. 12. The ink according to claim 11, wherein the coloring material has a carboxyl group. 13. The ink according to claim 12, wherein the coloring material is a monomer or a dimer having an azo structure. 14. The ink according to claim 13, wherein the coloring material has a linear structure or a cyclic compound having 4 or more carbon atoms. 15. The coloring material contains units represented by the following structural formulas (a) to (d) at both ends of a coloring material structure or at a bonding portion of a dimer, and at least the structural formula (c) or 15. The ink according to claim 14, having one (d). Embedded image (In the formula, A represents a divalent to trivalent linking group, R represents a linear structure or a cyclic compound having 4 or more carbon atoms, and L represents an integer of 1 to 3.) 16. An ink jet recording method in which an ink droplet is ejected from an orifice according to a recording signal to perform recording on a recording material, wherein the ink is the ink according to any one of claims 1 to 15. An inkjet recording method characterized by the above-mentioned. 17. The ink-jet recording method according to claim 16, wherein the ink is ejected by applying thermal energy to the ink. 18. A recording unit comprising an ink containing section containing ink and a head section for discharging the ink as ink droplets, wherein the ink is used.
5. A recording unit, which is the ink according to any one of items 5. 19. A head for ejecting ink droplets by applying thermal energy to ink.
A recording unit according to item 1. 20. The recording unit according to claim 18, wherein the ink containing section is formed of polyurethane, cellulose, or polyvinyl acetate. 21. An ink cartridge provided with an ink storage section for storing ink, wherein the ink is provided.
16. An ink cartridge comprising the ink described in any one of items 15 to 15. 22. The ink cartridge according to claim 21, wherein the ink container has a liquid contact surface formed of polyolefin. 23. An ink jet printing apparatus comprising: a printing unit having an ink storage section for storing ink and a head section for discharging the ink as ink droplets, wherein the ink is any one of claims 1 to 15. 13. An ink jet recording apparatus, comprising: 24. A head for ejecting ink droplets by applying thermal energy to the ink.
3. The ink jet recording apparatus according to claim 1. 25. The ink jet recording apparatus according to claim 23, wherein the ink containing section is made of polyurethane, cellulose, or polyvinyl acetate. 26. An ink jet recording apparatus comprising: a recording head for discharging ink droplets; an ink cartridge having an ink container containing ink; and an ink supply unit for supplying ink from the ink cartridge to the recording head. 16. The ink according to claim 1, wherein the ink is
13. An ink jet recording apparatus comprising the ink according to any one of the above items. 27. The ink jet recording apparatus according to claim 26, wherein the recording head is a head that applies thermal energy to the ink to eject ink droplets. 28. The ink jet recording apparatus according to claim 27, wherein the ink container has a liquid contact surface formed of polyolefin.