JPH08311383A - Recording liquid and ink jet recording method and recording apparatus using the same liquid - Google Patents

Abstract

PURPOSE: To obtain a recording liquid having good printing quality and light emitting property and improved also in scratching property without depending to kinds of media to be recorded and provide ink jet recording method and recording apparatus using the same. CONSTITUTION: This recording liquid containing at least pigment, an alkali- soluble type resin and water has (a) <=0.3μm average particle diameter of the pigment, (b) 100-120% neutralization ratio of an alkali-soluble type resin, <=20000 weight-average molecular weight and a content in an amount of >=3 times based on the pigment. This ink jet recording method and this recording apparatus comprise using the recording liquid.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording liquid suitable for an ink jet printer, an ink jet recording method and a recording apparatus using the same, and more particularly, the recording liquid is ejected from the orifice of a recording head by the action of thermal energy to be recorded. The present invention relates to an inkjet recording method and a recording apparatus for recording on a material.

[0002]

2. Description of the Related Art The ink jet recording system has an advantage that noise is not generated during recording and a high resolution recording image can be obtained at a high speed by using a highly integrated head. In such an ink jet recording system, as the ink, a solution in which various water-soluble dyes are dissolved in water or a mixed liquid of water and an organic solvent is used. However, when a water-soluble dye is used, these water-soluble dyes are originally inferior in light resistance, so that the light resistance of a recorded image often becomes a problem.

Since the ink is water-soluble, the water resistance of the recorded image often becomes a problem. That is, when the recorded image comes into contact with rain, sweat, water for drinking or the like, the recorded image may bleed or disappear.

On the other hand, stationery using a dye for ink such as a ballpoint pen has the same problem, and various aqueous pigment inks for stationery have been proposed in order to solve the problems of light resistance and water resistance. As an example of studying dispersion stability, prevention of ink solidification at a pen tip, prevention of abrasion of balls of a ballpoint pen, etc. for practical use of an aqueous pigment ink, JP-A-58-80368 and JP-A-58-80368 are cited. 61-20
0182, JP 61-247774, JP 61-272278, JP 62-568, JP 62-101671 and JP 62-
No. 101672, JP-A-1-249869,
JP-A-1-301760 and the like can be mentioned.

Recently, ballpoint pens and markers using water-based pigment ink have come to the market as commercial products. As an inkjet ink using a water-based pigment ink, a pigment ink using a specific water-soluble solvent and a polymer dispersant is proposed in JP-A-56-147859 and JP-A-56-147860. Has been done. Further, JP-A-4-57859 and JP-A-4-5786.
No. 0, etc. proposes an ink that uses a pigment and a dye together.

Various methods have been proposed for this ink jet recording method, some of which have been improved and commercialized, and some of which are still being put into practical use.

In this ink jet recording method, in order to satisfy the printing quality, it is extremely important that the non-volatile components in the ejected ink rapidly aggregate on the recording medium. On the other hand, in the case of a pigment, the dispersion having a particle size is larger than the dye molecule and has a stronger cohesive force. As the pigment agglomerates promptly with respect to the composition change, good printing quality can be obtained.

However, although the pigment has good aggregating property as described above, the aggregating property of the pigment causes the following problems. That is, (1) if the printed portion on the recording medium is strongly rubbed or traced with a highlighter pen, the rubbing property such as contamination of the printed surface is deteriorated. (2) Poor color development such as blocking the light transmission of OHP sheets and special papers and films with gloss.

[0009]

SUMMARY OF THE INVENTION The present invention solves the problems of the prior art that occur when the above-mentioned pigment ink is used, and the purpose of the invention is regardless of the type of recording medium. The present invention provides a recording liquid having good print quality, good light emitting property, and improved scratch resistance, and an inkjet recording method and a recording device using the same. Further, the present invention provides a recording liquid having good water resistance and light resistance which the pigment ink originally has.

[0010]

That is, according to the present invention, in a recording liquid containing at least a pigment, an alkali-soluble resin and water, (a) the average particle diameter of the pigment is 0.3 μm or less,
And the content thereof is 1 to 10% by weight, (b) the neutralization rate of the alkali-soluble resin is 100 to 120%, the weight average molecular weight is 20,000 or less, and the content is relative to the pigment. The recording liquid is characterized by being 3 times or more in total.

Further, the present invention is an ink jet recording method in which ink droplets formed by an ink jet method are adhered to a recording material for recording, and the above recording liquid is applied as the ink. Is.

Further, the present invention is an ink cartridge having an ink containing portion containing ink, wherein the recording liquid is applied as the ink.

Further, according to the present invention, in a recording unit having both an ink containing portion containing ink and a head portion for ejecting the ink as an ink droplet, the above recording liquid is applied as the ink. Is a recording unit.

Further, according to the present invention, there is provided an ink jet recording apparatus for performing recording by adhering ink droplets formed by an ink jet method to a recording material, the ink jet recording apparatus having the above ink cartridge or recording unit. is there.

The present invention will be described in detail below. The recording liquid of the present invention contains at least a pigment, an alkali-soluble resin, and water. (1) The content of the pigment is 1 to 10% by weight. (2) The average particle size of the pigment is 0.3 μm. (3) The content of the alkali-soluble resin is 3 times or more by weight% of the pigment (4) The neutralization rate of the alkali-soluble resin is 100 to 12
0% (5) The alkali-soluble resin has a weight average molecular weight (hereinafter abbreviated as average molecular weight) of 20,000 or less.

Furthermore, the present invention is an ink jet recording method and a recording apparatus for recording the recording liquid by applying thermal energy to the recording liquid and ejecting the recording liquid as droplets from the fine holes.

A first point of the present invention is, in ink jet recording, how to control aggregation of a pigment in a recording liquid ejected on a recording medium and fix the pigment.
Moreover, it is necessary to secure the ink jet recording suitability, that is, the stable ejection performance.

Therefore, as a result of earnest studies, the present inventor found that
When the alkali-soluble resin is contained in a weight ratio of 3 times or more, more preferably 5 times or more, and the average particle diameter of the pigment is 0.3 μm or less, more preferably 0.2 μm or less, It has been found that the light transmittance to an OHP sheet, a special paper having gloss and a film is improved, and a good abrasion property is obtained also to various recording media including these.

This is because when the recording liquid contains a certain amount or more of alkali-soluble type resin with respect to the pigment, the pigment aggregates on the recording medium due to evaporation and permeation of the liquid component in the ink. It is controlled by the interposition of a large amount of resin, and at this time the pigment particle size is more effective than a certain size or less, and at the same time, the pigment itself is covered by the film effect of this alkali-soluble resin. It is considered that this is due to the action of being fixed on the recording medium.

The content of the pigment used in the present invention is 1
10 to 10% by weight, more preferably 2 to 7% by weight. If it is less than 1% by weight, a sufficient image density cannot be obtained, and if it exceeds 10% by weight, the amount of the alkali-soluble resin to be used is increased, so that the viscosity of the entire ink is considerably increased and, as a result, the ink is discharged from the nozzle tip Therefore, it becomes impossible to stably discharge the ink.

The average particle size of the pigment used in the present invention is 0.3 μm or less, preferably 0.05 μm to 0.3 μm.
m, more preferably 0.05 μm to 0.2 μm.

The alkali-soluble resin used in the present invention preferably has an average molecular weight of 20,000 or less.
If it exceeds, the amount used in the viscous region where ejection is possible is limited, and a sufficient effect cannot be obtained. Further, it is preferably 5,000 to 20,000, more preferably 5,000 to 10,000, and in this range, there is an advantage that particularly stable ejection property can be obtained.

The content of the alkali-soluble resin is 3 times or more in weight% with respect to the pigment, preferably 3 to.
The range is preferably 10 times, more preferably 5 to 10 times.

Next, the second point of the present invention is that the alkali-soluble resin used in the present invention is water-soluble,
This means that the water resistance of the recorded matter is not always satisfactory. That is, the pigment mixed with a large amount of the water-soluble alkali-soluble resin on the recording medium is also washed with water together with the resin. Alternatively, it takes a very long time to develop water resistance.

Therefore, as a result of intensive studies, the present inventors have found that the neutralization rate when the alkali-soluble resin used in the present invention is neutralized with a basic substance to be water-soluble is 100 to 120.
%, And more preferably 100 to 110%, it was found that good water resistance can be obtained in a short time after recording. That is, when the neutralization ratio exceeds 120%, when an alkali-soluble resin aqueous solution is used to add a predetermined resin concentration in the recording liquid, a large amount of free basic substance is also present in the recording liquid. It will be. On the recording medium, this becomes an obstacle for the alkali-soluble resin to separate out the basic component and become water-insoluble, and thus it becomes impossible to exhibit good water resistance in a short time after recording.

The neutralization ratio as used in the present invention means the amount of a basic substance capable of dissolving an alkali-soluble resin from the acid value of the resin (mg amount of KOH for neutralizing the resin), and the following formula (1) It is a numerical value in which the amount of basic substance actually added is expressed in% with respect to the theoretical value obtained by.

[0027]

[Equation 1]

As the pigment used in the present invention, any pigment can be used as long as it satisfies the above-mentioned performance, but the carbon black used in the black ink is a carbon black produced by the furnace method or the channel method. The primary particle size is 15 to 40 nm, and the specific surface area by the BET method is
50-300 m ² / g, DBP lubrication amount is 40-150
ml / 100g, volatile content 0.5-10%, pH value 2
.About.9, for example, No. 2300, No. 900,
MCF88, No. 33, No. 40, No. 45, N
o. 52, MA7, MA8, No. 2200B (Made by Mitsubishi Kasei)

RAVEN1255 (manufactured by Colombia),
REGAL400R, REGAL330R, REGAL
660R, MOGULL (made by Cabot), Colo
r Black FW1, Color Black F
W18, Color Black S170, Colo
r Black S150, Printex 35, P
A commercially available product such as rintex U (manufactured by Degussa) can be used.

Pigments used in the yellow ink include C.I. I. Pigment Yellow 1, C.I.
I. Pigment Yellow 2, C.I. I. Pi
gment Yellow 3, C.I. I. Pigmen
t Yellow 13, C.I. I. Pigment
Yellow 16, C.I. I. Pigment Yel
low 74, C.I. I. Pigment Yellow
83,

As the pigment used as the magenta ink, C.I. I. Pigment Red 5, C.I. I.
Pigment Red 7, C.I. I. Pigment
Red 12, C.I. I. Pigment Red 4
8 (Ca), C.I. I. Pigment Red 48
(Mn), C.I. I. Pigment Red 57 (C
a), C.I. I. Pigment Red 112, C.I.
I. Pigment Red 122,

Pigments used as cyan ink include C.I. I. Pigment Blue 1, C.I. I.
Pigment Blue 2, C.I. I. Pigmen
tBlue 3, C.I. I. Pigment Blue
15: 3, C.I. I. Pigment 16, C.I. I. P
igment Blue 22, C.I. I. VatBlu
e 4, C. I. Vat Blue 6 and the like can be mentioned, but those newly manufactured for the present invention can also be used. Also, in order to improve the wettability of these pigments,
You may perform the surface treatment etc.

Examples of the dispersant usable in the present invention include higher fatty acid salts, alkyl sulfates, alkyl ether sulfates, alkyl ester sulfates, alkyl aryl ether sulfates, alkyl sulfonates, sulfosuccinates, alkyl allyls and Anionic surfactants such as alkylnaphthalene sulfonate, alkyl phosphate, polyoxyethylene alkyl ether phosphate, alkylaryl ether phosphate, polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether,
Polyoxyethylene polyoxypropylene glycol,
Nonionic surfactants such as glycerin ester, sorbitan ester, sucrose ester, polyoxyethylene ether of glycerin ester, fatty acid alkanolamide, polyoxyethylene fatty acid amide, amine oxide, or water-soluble resin such as styrene, styrene derivative, vinyl Selected from naphthalene derivatives, aliphatic alcohol esters of α, β-ethylenically unsaturated carboxylic acids, acrylic acid, acrylic acid derivatives, maleic acid, maleic acid derivatives, itaconic acid, itaconic acid derivatives, fumaric acid, fumaric acid derivatives, etc. Block copolymers or random copolymers composed of at least two or more of the above monomers, or salts thereof. These resins are alkali-soluble type resins that are soluble in an aqueous solution in which a base is dissolved, and have the advantage that they can be used in inkjet inks to reduce the viscosity of the dispersion liquid and are easy to disperse. Therefore, it is particularly preferably used.

Further, a homopolymer composed of a hydrophilic monomer or a salt thereof may be used. It is also possible to use water-soluble resins such as polyvinylpyrrolidone, polyvinyl alcohol, carboxymethyl cellulose, naphthalene sulfonic acid formaldehyde condensate, and natural resins such as rosin and shellac. The average molecular weight of these water-soluble resins is preferably in the range of 500 to 30,000, more preferably 1,000 to 15,000.

The water-soluble surfactant and water-soluble resin of the dispersant are contained in an amount of 0.5 to 10% by weight, preferably 1 to 5% by weight, based on the total weight of the recording liquid.

The alkali-soluble resin used in the present invention is
The resin is not particularly limited as long as it is a resin that is soluble in an aqueous solution in which a basic substance is dissolved, but it is an alkali-soluble resin that can be used as a dispersant for the above pigment and has an average molecular weight of 20,0.
It is preferable to use a resin of 00 or less, preferably 15,000 or less, from the viewpoint of dispersion stability of the pigment. Specifically, styrene, styrene derivatives, vinylnaphthalene derivatives, aliphatic alcohol esters of α, β-ethylenically unsaturated carboxylic acids, acrylic acid, acrylic acid derivatives, maleic acid, maleic acid derivatives, itaconic acid, itaconic acid Examples thereof include block copolymers composed of at least two monomers selected from derivatives, fumaric acid, and fumaric acid derivatives, and random copolymers.

As the basic substance for solubilizing the above alkali-soluble resin in water, monoethanolamine,
Diethanolamine, triethanolamine, ethylmonoethanolamine, ethyldiethanolamine, monoisopropanolamine, diisopropanolamine,
Alkanolamines such as triisopropanolamine, organic amines such as ammonia, or potassium hydroxide,
Although inorganic bases such as sodium hydroxide can be used, from the viewpoint of ejection stability in inkjet recording,
Particular preference is given to using alkanolamines.

A suitable aqueous medium in the ink of the present invention is a mixed solvent of water and a water-soluble organic solvent. As water, not ordinary water containing various ions but ion-exchanged water (deionized water) is used. Preference is given to using. The content of water in the recording liquid is usually 10 to 70% by weight,
It is preferably in the range of 20 to 50% by weight.

As other optional solvent components that can be used in combination, water-soluble organic solvents used by mixing with water include, for example, methyl alcohol, ethyl alcohol, n.
-Propyl alcohol, isopropyl alcohol, n-
Butyl alcohol, sec-butyl alcohol, ter
C1-C4 alkyl alcohols such as t-butyl alcohol: amides such as dimethylformamide and dimethylacetamide:

Ketones or ketone alcohols such as acetone and diacetone alcohol: Ethers such as tetrahydrofuran and dioxane: Polyalkylene glycols such as polyethylene glycol and polypropylene glycol: ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1 , 2, 6
-Alkylene glycols in which the alkylene group contains 2 to 6 carbon atoms, such as hexanetriol, thiodiglycol, hexylene glycol, diethylene glycol:

Lower alkyl ethers of polyhydric alcohols such as glycerin, ethylene glycol monomethyl (or ethyl) ether, diethylene glycol methyl (or ethyl) ether and triethylene glycol monomethyl (or ethyl) ether: N-methyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone and the like can be mentioned.

Among many of these water-soluble organic solvents,
Preferred are polyhydric alcohols such as diethylene glycol and lower alkyl ethers of polyhydric alcohols such as triethylene glycol monomethyl (or ethyl) ether.

Since the pH of the recording liquid of the present invention is such that the neutralization ratio of the alkali-soluble resin is 100 to 120%, the pH of the aqueous resin solution solubilized by adding a basic substance is used. Care must be taken in adding other components so that the pH does not become higher than the pH. The pH is preferably in the range of 8-10.

In addition to the above components, the recording liquid of the present invention may further contain a surfactant, an antifoaming agent, an antiseptic agent, etc. other than the above in order to obtain a recording liquid having desired physical properties. can do. Further, urea, thiourea, ethylene urea or a derivative thereof may be contained as a nozzle drying inhibitor.

On the other hand, the disperser used in the present invention may be any disperser generally used, and examples thereof include a ball mill, a roll mill and a sand mill. Among them, a high speed sand mill is preferable, For example, a super mill, a sand grinder, a bead mill, an agitator mill, a grain mill, a dyno mill, a pearl mill, a cobol mill (all are trade names) and the like can be mentioned.

In the present invention, as a method for obtaining a dispersion of a pigment having a desired particle size distribution, the size of the grinding media of the disperser is reduced, the packing ratio of the grinding media is increased, and the treatment time is lengthened. Techniques such as slowing down the discharge speed and classifying with a filter or a centrifuge after crushing are used. Alternatively, a combination of these methods can be cited.

Next, the method for preparing the recording liquid of the present invention is as follows.
First, a pigment dispersion liquid in which a pigment is dispersed is prepared, and water, a water-soluble organic solvent, an alkali-soluble resin solubilized in water, and the like are added thereto to a predetermined concentration.

In the ink jet recording method using ink as a recording liquid of the present invention, a recording head having a plurality of ink ejection ports applies ink to a recording material having no ink permeability to form a recorded image. An ink jet recording method, which comprises: a first step of cleaning the surface of the recording medium; and ink droplets are ejected from a discharge port of the recording head in accordance with an image recording signal to cause the ink droplets to reach a predetermined position on the recording medium. And a third step of curing the ink applied on the recording material.

Further, in the ink jet recording method of the present invention, the second step is preferably performed by a bubble jet recording method. As a method and apparatus suitable for performing recording using ink as the recording liquid of the present invention, a method of applying a thermal energy corresponding to a recording signal to the ink in the chamber of the recording head and generating a droplet by the thermal energy And devices.

An example of the head structure, which is the main part of the apparatus, is shown in FIGS. 1, 2 and 3. The head 13 is a glass, ceramic, or plastic plate having a groove 14 through which ink passes, and a heating head 15 used for heat-sensitive recording (a head is shown in the drawing, but is not limited to this).
It can be obtained by closely attaching and. The heating head 15 includes a protective film 16 for forming silicon oxide and the like, and an aluminum electrode 17-1.
17-2, heating resistor layer 1 formed of nichrome or the like
8, a heat storage layer 19, and a substrate 20 having a good heat dissipation property such as alumina.

The ink 21 has a discharge orifice (fine hole) 2
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, a region indicated by n of the heating head 15 rapidly generates heat, and bubbles are generated in the ink 21 in contact therewith,
The meniscus 23 is projected by the pressure, the ink 21 is ejected, becomes a recording droplet 24 from the orifice 22, and is ejected toward the recording material 25.

FIG. 3 shows an external view of a multi-head in which a large number of the heads shown in FIG. 1 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 in FIG. FIG.
2 is a cross-sectional view of the head 13 taken along the ink flow path, and FIG. 2 is a cross section taken along the line AB of FIG.

FIG. 4 shows an example of an ink jet recording apparatus incorporating such a head. In FIG. 4, reference numeral 61 denotes a blade as a wiping member, one end of which is held by a blade holding member to become a fixed end, which is in the form of a cantilever. The blade 61 is arranged at a position adjacent to the recording area of the recording head.

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

Reference numeral 65 denotes a recording head having an ejection energy generating means for ejecting ink to a recording material facing the ejection port surface where the ejection port is arranged for recording, and 66 is equipped with this recording head 65. And a carriage for moving the recording head 65. The carriage 66 slidably engages with the guide shaft 67, and a part of the carriage 66 is connected (not shown) to a belt 69 driven by a motor 68.
As a result, the carriage 66 can move along the guide shaft 67, and the recording head 65 can move the recording area and its adjacent area.

Reference numeral 51 is a paper feed section for inserting a recording material, and 52 is a paper feed roller driven by a motor (not shown). With these configurations, the recording material is fed to a position facing the ejection port surface of the recording head, and is ejected to a paper ejection unit provided with a paper ejection roller 53 as the recording progresses.

In the above structure, when the recording head 65 returns to the home position after the recording is completed, the head recovery unit 6
The fourth cap 62 is retracted from the movement path of the recording head 65, but the blade 61 is projected in the movement path. As a result, the ejection port surface of the recording head 65 is wiped. When the cap 62 comes into contact with the ejection surface of the recording head 65 to perform capping, the cap 62 moves so as to project 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 in the same position as the above-mentioned position during wiping. As a result, even during this movement, the ejection port surface of the recording head 65 is wiped.

The above-mentioned movement of the recording head to the home position is performed not only at the end of recording and at the time of ejection recovery, but also at the home adjacent to the recording area at a predetermined interval while the recording head moves in the recording area for recording. The wiper is moved to the position, and the wiping is performed along with the move.

FIG. 5 is a diagram showing an example of an ink cartridge in which the ink is supplied to the head via an ink supply member, for example, a tube. Here, reference numeral 40 is an ink containing portion containing 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 liquid contact surface of the ink containing portion is 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 separately provided as described above, but is also suitable for the one in which they are integrated as shown in FIG. Used.

In FIG. 6, reference numeral 70 denotes a recording unit, in which an ink containing portion containing ink, for example, an ink absorber is contained, and the ink in the ink absorber has a plurality of orifices. Head portion 71
It is configured to be ejected as an ink droplet from. For the present invention, it is preferable to use polyurethane as the material of the ink absorber.

Reference numeral 72 denotes an atmosphere communication port for communicating the inside of the recording unit with the atmosphere. This recording unit 70 is
It is used in place of the recording head shown in FIG. 4, and is detachable from the carriage 66.

[0064]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples. The parts shown below are parts by weight unless otherwise specified.

Example 1 (Preparation of Pigment Dispersion) Styrene-acrylic acid copolymer 5.0 parts (average molecular weight 7000) Monoethanolamine 1.0 part Ion-exchanged water 68.0 parts Diethylene glycol 5.0 parts

The above ingredients are mixed and mixed in a water bath to 70
The mixture was heated to 0 ° C. to completely dissolve the resin component. Carbon black (MCF88 manufactured by Mitsubishi Kasei) was added to this solution 20 times.
Parts and 1.0 part of isopropyl alcohol were added, and premixing was performed for 30 minutes, and then dispersion treatment was performed under the following conditions.

Disperser: Sand grinder Grinding media: Zirconium beads 1 mm diameter Packing ratio of grinding media: 50% (volume) Grinding time: 3 hours Further centrifugal treatment (12000 rpm, 20 minutes) is performed to remove coarse particles. It was a dispersion liquid.

(Preparation of Ink ) The ink was prepared by adding the following components to the above dispersion liquid so that the ink has a predetermined concentration. Dispersion 15 parts Glycerin 10 parts Diethylene glycol 15 parts 30% Styrene-acrylic acid copolymer aqueous solution 50 parts (Average molecular weight 7,000, monoethanolamine neutralization, neutralization rate 110%) Ion-exchanged water 10 parts Pigment in ink The average particle size was 0.12 μm.

(Note) The weight average molecular weight is a value measured by the GPC method using a styrene polymer as a standard, and the average particle diameter is a value measured by the dynamic light scattering method.

Example 2 (Preparation of Pigment Dispersion) Polyoxyethylene alkyl ether phosphoric acid 4.0 parts Monoethanolamine 1.0 part Ion-exchanged water 69.0 parts Diethylene glycol 5.0 parts

The above ingredients were mixed and mixed in a water bath to 70
The mixture was heated to 0 ° C. to completely dissolve the surfactant. C. I. 20 copies of Pigment Red 122,
After adding 1.0 part of isopropyl alcohol and performing premixing for 30 minutes, dispersion treatment was performed under the same conditions as in Example 1.

(Preparation of Ink ) Ink was prepared by adding the following components to the above-mentioned dispersion liquid so as to have a predetermined concentration. Dispersion 12 parts Glycerin 10 parts Diethylene glycol 15 parts 25% Styrene-acrylic acid-methyl methacrylate copolymer aqueous solution (average molecular weight 10,000, neutralization of diethanolamine, neutralization rate 103%) 50 parts Ion-exchanged water 13 parts Ink The average particle diameter of the pigment therein was 0.15 μm.

Example 3 (Preparation of Pigment Dispersion) Polyoxyethylene alkyl ether phosphoric acid 4.0 parts Monoethanolamine 1.0 part Ion-exchanged water 69.0 parts Diethylene glycol 5.0 parts

The above ingredients are mixed and mixed in a water bath to 70
The mixture was heated to 0 ° C. to completely dissolve the surfactant. C. I. Pigment Blue 15: 3 to 20
Parts and 1.0 part of isopropyl alcohol were added, premixed for 30 minutes, and then dispersed under the same conditions as in Example 1.

(Preparation of Ink ) The ink was prepared by adding the following components to the above dispersion liquid so as to have a predetermined concentration. Dispersion 12 parts Glycerin 10 parts Diethylene glycol 15 parts 25% Styrene-acrylic acid-methyl methacrylate copolymer aqueous solution (average molecular weight 13,000, monoethanolamine neutralization, neutralization rate 107%) 50 parts Ion-exchanged water 13 The average particle size of the pigment in the ink was 0.102 μm.

Example 4 (Preparation of Pigment Dispersion) Styrene-acrylic acid copolymer 5.0 parts (average molecular weight 7000) Monoethanolamine 1.0 part Ion-exchanged water 68.0 parts Diethylene glycol 5.0 parts

The above ingredients were mixed and mixed in a water bath to 70
The mixture was heated to 0 ° C. to completely dissolve the resin component. C. I. Pigment Yellow 74 20
Parts and 1.0 part of isopropyl alcohol were added, premixed for 30 minutes, and then dispersed under the same conditions as in Example 1.

(Preparation of Ink ) Preparation of ink was prepared by adding the following components to the above-mentioned dispersion liquid so as to have a predetermined concentration. Dispersion 15 parts Glycerin 10 parts Diethylene glycol 15 parts 25% Styrene-acrylic acid-methyl methacrylate copolymer aqueous solution (average molecular weight 10,000, monoethanolamine neutralization, neutralization rate 110%) 50 parts Ion-exchanged water 10 The average particle size of the pigment in the ink was 0.11 μm.

Example 5 (Preparation of Pigment Dispersion) Styrene-maleic acid-methyl methacrylate copolymer 5.0 parts (average molecular weight 8200) Monoethanolamine 1.0 part Ion-exchanged water 68.0 parts Ethylene glycol 5 .0 copy

The above ingredients were mixed and mixed in a water bath to 70
The mixture was heated to 0 ° C. to completely dissolve the resin component. Carbon black (MCF88 manufactured by Mitsubishi Kasei) was added to this solution 20 times.
Parts and 1.0 part of isopropyl alcohol were added, premixed for 30 minutes, and then dispersed under the same conditions as in Example 1.

(Preparation of Ink ) The ink was prepared by adding the following components to the above dispersion liquid so as to have a predetermined concentration. Dispersion 25 parts Glycerin 10 parts Diethylene glycol 15 parts 34% Styrene-acrylic acid copolymer aqueous solution 50 parts (average molecular weight 7,000, monoethanolamine neutralization, neutralization rate 102%) The average particle size of the pigment in the ink is 0. It was 0.17 μm.

Comparative Example 1 In the preparation of the ink of Example 1, the neutralization rate of 140% was 3
50 parts of 0% styrene-acrylic acid copolymer aqueous solution was prepared. The average particle size of the pigment in the obtained ink is 0.
It was 102 μm.

Comparative Example 2 In the preparation of the ink of Example 2, a 25% styrene-methyl methacrylate copolymer aqueous solution was added in an amount of 10 parts. The average particle size of the pigment in the obtained ink is 0.1.
It was 4 μm.

Comparative Example 3 In the preparation of the ink of Example 1, the average molecular weight was 25,0.
00 solubilized styrene-acrylic acid copolymer 3
A 0% aqueous solution was prepared as 50 parts. The average particle size of the pigment in the obtained ink was 0.11 μm.

Examples 1 to 5 obtained as described above,
Table 1 shows the results of the following examinations by a recording apparatus BJ-200 (manufactured by Canon Inc.) having an on-demand type multi-head that ejects ink by applying thermal energy using the inks of Comparative Examples 1 to 3. Show.

(1) Ejection stability ◯: Ejection is clear from the first character, and there is almost no ejection failure, chipping, or print disturbance during continuous printing. Δ: Characters are ejected relatively cleanly, but non-ejection occurs at several spots in solid printing. X: Even in the character portion, when several characters are printed, non-ejection occurs, and the printing is disturbed to the extent that the characters cannot be read.

(2) Light transmission on recording medium Color development when printed OHP sheet CF-102 (manufactured by Canon Inc.) is applied to OHP, and gloss paper GP-101.
(Canon) or white PET (polyethylene terephthalate) coated with a 10% aqueous solution of polyvinyl alcohol was used to evaluate the color developability on the glossy film. ◯: Original color was developed, and O. D is also high. Δ: Slightly lacking in color developability, O. D is low. X: The color is darkened.

(3) Scratchability The image obtained by printing was allowed to stand for 1 day and then evaluated by rubbing with a hand or erasing with an eraser. ◯: Even if it was rubbed 5 times with an eraser, characters and solid images were hardly erased and hands were not soiled. Δ: A little inferior level. X: Substantially a problematic level.

(4) Water resistance A sample printed on Xerox 4024 paper was treated with tap water.
After soaking for a minute, the change in the optical density of the printed matter before and after the treatment was expressed by the residual rate. ◯: Residual rate is 98% or more Δ: Residual rate is 90 to 97% ×: Residual rate is 89% or less

[0090]

[Table 1]

[0091]

According to the present invention, regardless of the type of recording medium, especially on an OHP sheet or a special paper or film having gloss, the print quality and color developability are good, and the scratchability is high. It is possible to provide a recording liquid having excellent water resistance and inkjet recording having excellent ejection stability.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a head portion of an inkjet recording device.

FIG. 2 is a vertical cross-sectional view of a head portion of an inkjet recording device.

FIG. 3 is an external perspective view of a head in which the heads shown in FIGS. 1 and 2 are multi-headed.

FIG. 4 is a perspective view showing an example of an inkjet recording apparatus.

FIG. 5 is a vertical sectional view of an ink cartridge.

FIG. 6 is a perspective view of a recording unit.

[Explanation of symbols]

 1 Ink Tank 2 Inkjet Recording Head 3 Inkjet Recording Device 13 Head 14 Groove 15 Heating Head 16 Protective Film 17-1, 17-2 Aluminum Electrode 18 Heating Resistor Layer 19 Thermal Storage Layer 20 Substrate 21 Ink 22 Ejection Orifice 23 Meniscus 24 Small Recording Droplet 25 Recording material 26 Multi-groove 27 Glass plate 28 Heating head 40 Ink storage section 42 Plug 44 Ink absorber 45 Ink cartridge 51 Paper feeding section 52 Paper feeding roller 53 Paper ejection roller 61 Wiping member 62 Cap 63 Ink absorbing body 64 Discharge Recovery unit 65 Recording head 66 Carriage 70 Recording unit 71 Orifice tip 72 Atmosphere communication port 73 Substrate

Claims (9)

[Claims] 1. A recording liquid containing at least a pigment, an alkali-soluble resin and water, wherein (a) the average particle diameter of the pigment is 0.3 μm or less, and the content is 1 to 10% by weight.
And (b) the neutralization rate of the alkali-soluble resin is 10
0 to 120%, weight average molecular weight of 20,000 or less,
A recording liquid whose content is 3 times or more that of the pigment. 2. The recording liquid according to claim 1, which contains a basic substance capable of dissolving the alkali-soluble resin in water. 3. The recording liquid according to claim 2, wherein the basic substance is an alkanolamine. 4. In an inkjet recording method for recording by causing ink droplets formed by an inkjet method to adhere to a recording material, the recording liquid according to any one of claims 1 to 3 is applied as the ink. An inkjet recording method characterized by the above. 5. The ink jet recording method according to claim 4, wherein the ink jet method is a method in which thermal energy is applied to the ink. 6. An ink cartridge having an ink containing portion containing ink, wherein the recording liquid according to any one of claims 1 to 3 is applied as the ink. 7. A recording unit having both an ink containing portion containing ink and a head portion for ejecting the ink as ink droplets, wherein the ink is the ink according to any one of claims 1 to 3. A recording unit characterized by applying a recording liquid. 8. The recording unit according to claim 7, wherein thermal energy is applied to the ink to eject the ink in the head portion. 9. An inkjet recording apparatus for recording by recording ink droplets formed by an inkjet method on a recording material, comprising the ink cartridge or the recording unit according to any one of claims 6 to 8. An inkjet recording device characterized by the above.