JPH06228478A - Ink set and color image formation therewith - Google Patents

Abstract

PURPOSE:To provide a color image-forming method which gives the images of excellent color reproducibility without bleeding. CONSTITUTION:In a color image formation where a colorless liquid is applied before or after ink is applied to the recording paper, the mixture is thickened, or one component in the ink coagulates or precipitates, when the liquid contacts with the ink, further the colorless liquid and the ink are controlled so that their rates of penetration into paper differ from each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink set capable of obtaining a high-quality color image on plain paper and a method for forming a color image using the ink set.

[0002]

2. Description of the Related Art An ink jet recording method is one in which a recording liquid (ink) droplet is ejected and adhered to a recording material such as paper for recording. In particular, Japanese Examined Patent Publication Sho 61-5991
1, Japanese Patent Publication No. 61-59912, Japanese Patent Publication No. 61
According to the method disclosed in Japanese Patent Laid-Open No. 59914/1999, in which an electrothermal converter is used as a discharge energy supply unit and heat energy is applied to ink to generate bubbles, the droplets are discharged, thereby providing a high density multi recording head. The orifice can be easily realized, and high-resolution and high-quality images can be recorded at high speed.

However, conventional inks used for ink jet recording generally contain water as a main component and a water-soluble high-boiling point solvent such as glycol for the purpose of preventing drying and clogging. When recording on plain paper with such ink, the ink penetrates inside the recording paper and a sufficient image density cannot be obtained, or the filler and sizing agent on the recording paper surface are unevenly distributed. The unevenness of the image density, which is considered to be caused by the above, occurred. In particular, when a color image is to be obtained, the inks of a plurality of colors are successively overlapped before being fixed, so that the color is blurred or unevenly mixed at the boundary of the different color images. A satisfactory image (hereinafter referred to as bleeding) was not obtained.

As a means for improving the fixing property, Japanese Patent Laid-Open No. 55-
It is possible to use an ink containing a compound that enhances permeability such as a surfactant in the ink disclosed in JP-A-65269, and to use an ink mainly containing a volatile solvent in JP-A-55-66976. It is disclosed. However, in the former method, the permeability of the ink into the recording paper is improved, and although bleeding can be suppressed to some extent, the colorant of the ink penetrates deep into the recording paper,
There are inconveniences such as a decrease in image density and a decrease in image clarity. Further, since the wettability with respect to the surface of the recording paper is improved, the ink tends to spread, resulting in a decrease in resolution and bleeding, which is not preferable. On the other hand, in the case of the latter, in addition to the disadvantage of the former, clogging due to evaporation of the solvent in the nozzle portion of the recording head is likely to occur, which is not preferable.

Further, a method of depositing a liquid for improving an image on a recording paper prior to jetting the recording ink is disclosed. For example, JP-A-63-29971 discloses a method of recording an ink containing an anionic dye after depositing a liquid containing an organic compound having two or more cationic groups per molecule. JP-A-64-9
Japanese Patent Laid-Open No. 279/1982 discloses a method of recording an ink after depositing an acidic liquid containing succinic acid or the like.
Japanese Patent No. 63185 discloses a method of adhering a liquid insolubilizing a dye before recording. All of these methods improve the fixability and water resistance of a recorded image by precipitating the dye itself in the ink. But,
In any of the above cases, bleeding can be suppressed to some extent, but the deposited dye is deposited unevenly on the recording paper, so the coverage of the paper fibers of the recording paper is poor, and white voids become a noticeable image, and The rubbing property of the image was poor, and it was not preferable because it would fall off when rubbed with a finger and stain the recording paper.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and in plain paper recording, it has good fixing properties, good character quality, and sufficient image density. , An ink set having a high uniformity of image density, preventing bleeding particularly in a color image, having good color reproducibility, and obtaining a clear and uniform high-quality image, and also having good image scratchability The present invention provides a method for forming a color image using the.

[0007]

That is, the present invention is an ink set comprising a colorless liquid and an ink, wherein thickening occurs when the colorless liquid and the ink are mixed, or An ink set comprising a colorless liquid and an ink adjusted such that one component aggregates or precipitates, and the permeation rate into paper is different between the ink and the colorless liquid.

Further, the present invention is a method for forming a color image by applying a colorless liquid before or after applying the ink to the recording paper, and thickening occurs when the colorless liquid and the ink are mixed. Alternatively, a colorless liquid and an ink are prepared such that one component of the ink causes aggregation or precipitation and the permeation speed into paper is different between the ink and the colorless liquid. Is the way.

According to the present invention, a color ink jet recorded matter on plain paper, which has a good fixing property, does not deteriorate in character quality, has no bleeding, and has good color reproducibility, can be obtained.

Next, the function and effect of the present invention, that is, the permeation speed of the colorless liquid and the ink to the recording paper is made different to increase the permeation speed of the ink, and the viscosity is increased when the colorless liquid and the ink are mixed. Describe the effect of causing it. In the case of inkjet recording, there is generally a correlation between the permeation speed on plain paper and the dot shape.The higher the permeation speed, the more the dot shape becomes less circular and the more the dot bleeds, resulting in lower character quality. To do. According to the knowledge of the present inventor, when ink having a high penetration speed and ink having a low penetration speed with respect to a recording paper are printed at the same position by using an ink jet head, regardless of the recording order of the two types of ink, a mixed ink The permeation rate is close to that of ink with high permeation rate. Such a phenomenon is remarkable when the ink having a high penetration rate is extremely enhanced by the action of the penetrant such as a surfactant or a monohydric alcohol. Therefore, if there is no phenomenon of thickening when a colorless liquid and ink are mixed or a part of the components of the ink causing aggregation or precipitation, which is another constituent feature of the present invention, the penetration of the colorless liquid and ink When the speeds are made different, the fixing speed on plain paper is increased, but the shape of the dodd is destroyed, and as a result, the character quality is deteriorated.

However, when the phenomenon of thickening due to the mixing of the colorless liquid and the ink or the phenomenon that a part of the components of the ink aggregates or precipitates is used, the permeation rate of the colorless liquid into the recording paper is set to be higher than that of the ink. If it is set too low, the ink is ejected before the colorless liquid spreads on the recording paper, and the thickening that follows the mixing of the liquids occurs. , The spreading suppression force by precipitation is antagonized to reduce bleeding, and penetration in the depth direction is also suppressed. As a result,
Since the fixing property is good, the printing quality is not deteriorated, and the color material is fixed near the surface of the recording paper, a color inkjet recorded image having a high image density and a wide color reproduction range can be obtained.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Next, preferred embodiments of the present invention will be described to explain the present invention in detail.

First, as a method for making a difference in the permeation rate of a colorless liquid and ink into a recording paper, a conventionally known penetrant, more specifically, a surfactant, a monohydric alcohol,
Examples thereof include addition of polyhydric alcohols and polyethyl alcohol monoethyl ether and diethyl ether derivatives.

Next, a concrete example will be described below as a thickening method when a colorless liquid and ink are mixed or a method of causing a part of the components of the ink to aggregate or precipitate.

(1) pH change due to mixing of two liquids (a) Combination of alkali-soluble resin and acidic substance (b) Use of polymer substance causing sol-gel transition due to pH change (2) With certain polymer substance Thickening, aggregation, and precipitation due to the interaction of electrolytes (3) Thickening, aggregation, and precipitation by mixing a water-soluble polymer and a liquid containing a solvent that does not dissolve it (4) Water-soluble polymer and its association Forming and thickening,
Alternatively, a combination of specific solvents that cause aggregation or precipitation may be used, but the thickening method of the two liquids is not limited to the above method.

A more specific configuration example of each of the above methods will be described below, but the present invention is not limited to the following method.

(Combination of alkali-soluble resin and acidic substance) As the alkali-soluble resin, natural alkali-soluble polymers such as casein, zein and pectic acid, or
A copolymer resin of a hydrophilic monomer and a hydrophobic monomer is preferably used. As the hydrophilic monomer, an acrylic group,
Monomers that have side chains such as sulfo groups, carboxyl groups, hydroxyl groups, amide groups, amino groups, ether groups, and pyrrolidone groups as hydrophilic groups in the basic main chain such as methacrylic groups, vinyl groups, ether groups, maleic anhydride groups, etc. Is used. As the hydrophobic monomer, styrene, acrylic acid ester, isobutylene, etc. are preferably used. In particular,
Styrene-acrylic acid resin, styrene-acrylic acid-acrylic acid ester resin, styrene-maleic anhydride resin, styrene-maleic anhydride half ester resin, isobutylene-maleic anhydride resin, rosin-modified maleic anhydride resin, and others, water-soluble Alkyd, water-soluble polyester, water-soluble polyamide and the like are used.

There are no particular restrictions on the other physical properties of the alkali-soluble resin, but a weight average molecular weight of 1,000 to 100,000 is more preferable. 100
If it is less than 0, the desired effect is small, and if it exceeds 100,000, the initial viscosity of the ink is increased and the ejection characteristics are deteriorated, which is somewhat undesirable. Further, as the amount of the alkali-soluble resin added to the recording ink,
0.1 to 30% by weight is a preferable range. If it is less than 0.1% by weight, the desired effect is small, and if it exceeds 30% by weight, the initial viscosity of the recording ink increases, which is not preferable.

The alkali agent used for solubilizing the alkali-soluble resin is sodium hydroxide, sodium carbonate, ammonium carbonate, ammonia,
Sodium acetate, ammonium acetate, morpholine and monoethanolamine, diethanolamine, triethanolamine, ethylmonoethanolamine, n-butylmonoethanolamine, dimethylethanolamine,
Diethylethanolamine, ethyldiethanolamine, normal butyldiethanolamine, dinormalbutylethanolamine, monoisopropanolamine,
Alkanolamines such as diisopropanolamine and triisopropanolamine can be used. The amount of the alkali agent used varies depending on the amount of the alkali-soluble resin used, but is preferably 5 to 100% by weight based on the alkali-soluble resin.

Examples of the acidic substance that thickens by interacting with the alkali-soluble resin include inorganic acids and water-soluble resins having one or more carboxyl groups or anhydrides in the unit molecule. . As the water-soluble resin, specifically, a natural water-soluble polymer having one or more carboxyl groups or one of its anhydrides in a unit molecule, or a synthetic water-soluble resin is used. More specifically, natural water-soluble polymers such as alginic acid, carboxymethyl cellulose, pectinic acid, and carboxymethylated starch, and acrylic acid, methacrylic acid, itaconic acid, and polymers using maleic anhydride as a monomer, Or
A synthetic water-soluble resin such as a copolymer of the above-mentioned monomer and a hydrophilic monomer having a hydrophilic group such as a hydroxyl group, an amide group, an amino group, an ether group, a pyrrolidone group and an ethyleneimine group in the molecule is used. Examples of the resin include homopolymers of polyacrylic acid, polymethacrylic acid, polyitaconic acid, polymaleic acid and the like, copolymer resins of carboxyl group-containing monomers such as acrylic acid itaconic acid copolymer resin and acrylic acid methacrylic acid copolymer resin, Further, methyl vinyl ether maleic anhydride copolymer resin, methyl vinyl ether maleic anhydride alkyl monoester copolymer resin,
A copolymer resin of a hydrophilic group-containing monomer such as a copolymer resin of acrylic acid and N-vinyl-pyrrolidone is preferably used.

There are no particular restrictions on the other physical properties of the water-soluble resin, but a weight average molecular weight of 10 is more preferable.
The range of 00-500000 is preferable. If it is less than 1000, the desired thickening effect is small, and if it exceeds 500,000, the initial viscosity as a liquid is increased and the ejection characteristics are deteriorated, which is not preferable. The acid value of the resin is preferably 200 or more. If it is less than 200, the solubility in water is slightly insufficient, which is not preferable in some cases. The amount of the water-soluble resin added is preferably 0.1 to 30% by weight. If it is less than 0.1% by weight, the desired effect is small, and if it exceeds 30% by weight,
This is not preferable because the initial viscosity of the colorless liquid increases.

(Interaction between polymer substance and electrolyte) For example, gelation due to the interaction between carrageenan and a divalent cation such as calcium ion, or viscosity increase due to decrease in solubility due to the action of a salt of a water-soluble polymer, Or agglomeration,
Precipitation.

(Interaction between water-soluble polymer and solvent that does not dissolve it) For example, a combination of water-soluble cellulose and an organic solvent such as glycerin.

(Combination of Water-Soluble Polymer and Solvent that Increases Viscosity by Forming Aggregate with the Water-Soluble Polymer) In carrying out the present invention, elements other than those described above which form a colorless liquid and a recording ink will be described. .

The colorless liquid usually contains water and, if necessary, a water-soluble organic solvent, in addition to a component that causes a thickening when mixed with the ink. Examples of the water-soluble organic solvent include amides such as dimethylformamide and dimethylacetamide, ketones such as acetone, ethers such as tetrahydrofuran and dioxane, polyalkylene glycols such as polyethylene glycol and polypropylene glycol, ethylene glycol, propylene glycol and butylene. Glycol, triethylene glycol,
1,2,6-hexanetriol, thiodiglycol,
Alkylene glycols such as hexylene glycol and diethylene glycol, lower alkyl ethers of polyhydric alcohols such as ethylene glycol methyl ether, diethylene glycol monomethyl ether and triethylene glycol monomethyl ether, monohydric alcohols such as ethanol and isopropyl alcohol, and glycerin , N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, triethanolamine, sulfolane, dimethyl sulfoxide and the like are used. The content of the water-soluble organic solvent is not particularly limited,
A preferable range is 1 to 80% by weight.

In addition, if necessary, a viscosity adjusting agent, pH
You may mix | blend additives, such as a regulator, a preservative, a surface-active agent, an antioxidant, and an evaporation promoter.

Another physical property of the colorless liquid is p
H is preferably in the range of 1 to 7. If less than 1,
When jetting a colorless liquid, deterioration of the material of the recording head may occur, which is not preferable.
It is not preferable because the desired effect is small.

The colorless liquid is preferably colorless and transparent, but may be a light color as long as the color tone of the recording ink is not changed. However, the light color refers to a case where the resin or solvent to be blended is not colored positively, but is lightly colored.

Next, after the colorless liquid is adhered, the ink is adhered to form an image. The ink is a liquid when mixed with at least water, an organic solvent, a dye, and the colorless liquid. It is composed of ingredients that cause thickening.

As the dye used in the recording ink, most of the water-soluble acid dyes, direct dyes, basic dyes and reactive dyes described in the color index (COLOR INDEX) can be used. Also,
Even those not listed in the color index can be used as long as they are water-soluble dyes. The amount of the dye used is not particularly limited, but is preferably in the range of 0.1% by weight to 20% by weight based on the total weight of the ink.

As the ink, for example, disperse dye,
Dispersed inks containing pigments as colorants can also be used.
When such a disperse ink is used, when it is mixed with a colorless liquid, it is a colorless ink that causes thickening of the recording ink or aggregation of the coloring material due to destruction of the dispersed state due to pH change or electrolyte concentration change. It is possible to use the combination with the liquid.

As the organic solvent used for the ink, the organic solvent used for the colorless liquid can be similarly used. The content of the organic solvent is not particularly limited,
It is preferably 1% by weight to 80% by weight with respect to the total amount of ink.

In addition to the above, the ink may contain additives such as a viscosity adjusting agent, a pH adjusting agent, an antiseptic agent, a surfactant, an antioxidant and an evaporation accelerator, if necessary.

The recording paper used in the present invention is not particularly limited, and plain paper which has been conventionally used is preferably used.

In a preferred embodiment of the color image forming method of the present invention, the colorless liquid and the ink are used, and the colorless liquid is first adhered to the recording paper prior to the ink, and particularly the recording paper is heated or forced. The recording image is obtained by adhering the ink to the portion to which the colorless liquid is adhered, without drying.

As a method of adhering the colorless liquid to the recording paper, a method of adhering the colorless liquid to the entire surface of the recording paper with a spray, a roller or the like can be considered. It is preferable to carry out by an inkjet method capable of selectively adhering only to and uniformly adhering thereto. When a colorless liquid is attached by the inkjet method, it is necessary to attach the colorless liquid in advance to at least the portion where the ink is attached.

The time until the colorless liquid is adhered to the recording paper and then the ink is adhered is not particularly limited.

As a method for attaching the colorless liquid and the ink to the recording paper, various ink jet methods can be used, but a particularly preferable method is to eject droplets by using bubbles generated by thermal energy. Is.

Next, the recording apparatus used in the present invention will be described. In the present invention, it is preferable to apply a recording signal to the recording ink of the recording head and eject the droplets by the generated thermal energy. The structure of the recording head, which is the main part of the apparatus, is shown in FIGS.

The head 13 has a heating head 15 having a heating resistor used for heat-sensitive recording, such as glass, ceramics, or plastic in which ink is formed as a flow path (a head is shown in the figure, but the present invention is not limited to this. Not a thing)
It is obtained by bonding and. The heating head 15 includes a protective film 16 made of silicon oxide or the like, an aluminum electrode 17-
1, 17-2, heating resistor layer 1 formed of nichrome, etc.
8, a heat storage layer 19, and a substrate 20 having a good heat dissipation property such as alumina.

The recording ink 21 reaches the ejection orifice 22 and forms a meniscus 23 by the pressure P.

Here, when an electric signal is applied to the electrodes 17-1 and 17-2, the area indicated by n of the heating head 15 rapidly generates heat, and air bubbles are generated in the ink 21 in contact therewith, The meniscus is ejected by the pressure, becomes a recording droplet 24 from the orifice 22, and flies toward the recording material 25. FIG. 3 shows a schematic view of a recording head in which a large number of nozzles shown in FIG. 1 are arranged. The recording head is made by closely adhering a glass plate or the like 27 having a large number of flow paths to a heating head 28 similar to that described in FIG.

Incidentally, FIG. 1 shows the head 1 along the ink flow path.
3 is a sectional view of FIG. 3, and FIG. 2 is a sectional view taken along line AB of FIG. 1.

FIG. 4 shows an example of an ink jet recording apparatus incorporating the head.

In FIG. 4, reference numeral 61 is 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 wrench lever. The blade 61 is arranged at a position adjacent to the recording area of the recording head, and is configured to move in a direction perpendicular to the moving direction of the recording head to come into contact with the ejection port surface to perform capping. Further, 63 is an ink absorber provided 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 from the ink ejection port surface.

Reference numeral 65 denotes a recording head which has an ejection energy generating means and ejects ink to a recording material facing the ejection port surface where the ejection ports are arranged for recording, and 66 denotes a recording head in which the recording head 65 is mounted. A carriage for moving 65. The carriage 66 is movably engaged with the guide shaft 67, and a part of the carriage 66 is connected to a belt 69 (not shown) 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 denotes a paper feed section for inserting a recording material,
A paper feed roller 52 is driven by a motor (not shown). With these configurations, the recording material is fed to a position facing the ejection opening surface of the recording head, and as recording progresses, the recording material is ejected to a paper ejection unit provided with a paper ejection roller 53.

In the above structure, when the recording head 65 returns to the home position after recording is completed, the cap 62 of the head recovery section 64 is retracted from the movement path of the recording head 65, but the blade 61 is projected into the movement path. There is. As a result, the ejection port surface of the recording head 65 is wiped. When the cap 62 comes into contact with the ejection port 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 positions as the above wiping positions. As a result, the ejection opening surface of the recording head 65 is wiped even during this movement.

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 ink is supplied to the head through an ink supply member, for example, a tube. Here, 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. Four
Reference numeral 4 is an absorber that receives waste ink.

As the ink containing portion, it is preferable that the surface in contact with the ink is made of polyolefin, especially 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 as described above, and the one in which they are integrated as shown in FIG. 6 is also preferably used. .

In FIG. 6, reference numeral 70 denotes a recording unit in which an ink containing portion for containing ink, for example, an ink absorber is contained, and the ink in the ink absorber has a plurality of orifices. It is configured to be ejected as an ink droplet from the portion 71. As a material for the ink absorber, for example, polyurethane can be used. Reference numeral 72 is an atmosphere communication port for communicating the inside of the recording unit with the atmosphere. This recording unit 70 is shown in FIG.
It is used instead of the recording head shown in FIG. In the recording apparatus used in the present invention, an ink jet recording apparatus that applies thermal energy to ink to eject ink droplets has been described above as an example. However, in addition to this, a piezo type ink jet recording apparatus that uses a piezoelectric element may also be used. Available as well.

When carrying out the recording method of the present invention, for example, a recording apparatus in which five recording heads shown in FIG. 3 are arranged on a carriage is used. FIG. 7 shows an example thereof. Recording heads 81, 82, 83, and 84 respectively eject yellow, magenta, cyan, and black recording inks. Reference numeral 85 is a head for ejecting a colorless liquid. The head is arranged in the above-described recording device and ejects recording ink of each color according to a recording signal. Prior to that, the colorless liquid is attached in advance to at least a portion where the recording ink of each color is attached to the recording paper. Although FIG. 7 shows an example in which five recording heads are used, the present invention is not limited to this, and as shown in FIG. 8, one recording head can be used to eject yellow, magenta, cyan, black, and colorless liquids. It is also preferable that the flow paths be divided.

[0056]

EXAMPLES The present invention will be described more specifically below with reference to examples and comparative examples. In the following description, parts and% are based on weight unless otherwise specified.

Example 1 and Comparative Example 1 First, the following components were mixed and dissolved, and then pressure-filtered with a membrane filter (trade name: Fluoropore filter, manufactured by Sumitomo Electric Industries) having a pore size of 0.22 μm to give a colorless solution. Liquid A was obtained. (A) Methyl vinyl ether maleic anhydride copolymer (Mw = 20000) 1 part Thiodiglycol 20 parts Water 79 parts

Next, the following components were mixed and dissolved, and then pressure-filtered with a membrane filter (trade name: Fluoropore filter, manufactured by Sumitomo Electric Co., Ltd.) having a pore size of 0.22 μm to obtain yellow, magenta, cyan, and black recording inks. (1) -Y, (1) -M, (1) -C, (1) -Bk
Got (1) -Y Rosin-modified maleic acid resin (Mw = 100
00) 3 parts Sodium hydroxide 0.5 parts C.I. I. Direct Yellow 86 2 parts Thiodiglycol 30 parts Acetylenol EH (Surfactant from Kawaken Fine Chemicals) 1 part Water 63.5 parts (1) -M; I. Acid Red-289
The same composition as (1) -Y except that the amount of water was changed to 2.5 parts and 62 parts of water. (1) -C; I. Acid Blue-9 2.
Same composition as (1) -Y, except that 5 parts and 62 parts of water were used. (1) -Bk; dye is C.I. I. Food Black-2 3
The composition is the same as (1) -Y, except that 61.5 parts of water is used as the parts.

When the pH of each of the above recording inks was measured, all were in the range of pH = 8-12.

Next, recording was performed on commercially available copy paper and bond paper using the obtained colorless liquid and recording ink. As the ink jet recording apparatus used, the same recording apparatus as shown in FIG. 4 was used, and a color image was formed using the five recording heads shown in FIG. As the recording head used here, the same recording head as that used in BJC820 (trade name, Canon inkjet printer) was used. The drive condition of the recording heads, that is, the condition for energizing the heater is that the applied voltage is 2 for each head.
The driving frequency was 8 V, the pulse width was 3.2 μsec, and the driving frequency was 5 kHz.

Colorless liquid (A), recording ink (1)
Were combined and recorded.

The evaluation method of the recorded matter was as follows.

(Recording Density) A colorless liquid was applied to a commercially available copy paper, a black solid portion was recorded, and after leaving for 1 hour, the recording density was measured by Macbeth RD915 (trade name: manufactured by Macbeth). The following evaluation criteria were used. ◯: The density was 1.25 or higher. Δ: The density of each color was 1.15 to 1.25. X: The density of each color was 1.15 or less.

(Fixability) After a colorless liquid was applied to a commercially available copy paper, printing was carried out in which the two colors of yellow and magenta were overlaid, and the time at which no image flow occurred even after rubbing with a finger after printing was measured. .

When the fixing property is within 20 seconds, it is designated as ○.
Seconds to 30 seconds were marked with Δ, and 30 seconds or longer were marked with x.

(Character Quality) After a colorless liquid was applied to a commercially available copy paper, black alphanumeric characters were printed and the character quality was visually evaluated.

The case where the feathering was inconspicuous was designated as ◯.

(Bleeding) Commercially available copy paper and bond paper were provided with a colorless liquid, and then solid portions of respective colors of yellow, magenta, cyan, and black were recorded adjacently,
It was observed whether or not the colors were bleeding at the boundary between the colors or the colors were not mixed uniformly. The evaluation was based on the following criteria. ◯: No color bleeding or non-uniform mixture was observed. Δ: There were some areas where colors were bleeding or were mixed non-uniformly, but there is no practical problem. X: Colors are bleeding or mixed nonuniformly, which is a problem in practical use.

The evaluation results are shown in Table 2. As described in Table 2, in Example 1, a recorded image having good fixability, character quality, image density, and bleeding was obtained.

For comparison, the same ink jet recording as in Example 1 was carried out except that the colorless liquid used in Example 1 was not used. The results are shown in Table 2.
As is clear from Table 2, an image with poor character quality was obtained at low density.

Examples 2 to 4 Recording was carried out using the combinations of the colorless liquids (B), (C) and (D) shown below and the recording inks (2), (3) and (4) (Table 1). did. Liquid composition (B) Polyethylene glycol (Mw = 600) 50 parts Water 50 parts Liquid composition (C) Glycerin 30 parts Water 70 parts Liquid composition (D) Methyl vinyl ether maleic anhydride copolymer (Mw =
20000) 1 part Thiodiglycol 20 parts Water 79 parts Recording ink (2) (2) -Y Natural polysaccharide (Hayashibara Research Laboratories Trigluco-
A Mw = 200000) 0.5 part C.I. I. Direct Yellow 86 2 parts Thiodiglycol 30 parts Acetylenol EH (surfactant manufactured by Kawaken Fine Chemicals) 1 part Water 66.5 parts (2) -M, C, Bk; C, M, B of recording ink (1)
Use the same dye as k and add the same amount, and add 10
Adjusted to be 0 copy. Recording ink (3) (3) -Y Water-soluble cellulose ether (hydroxypropyl cellulose manufactured by Nippon Soda; HPC-SL molecular weight: 30,000 to 50,000) 3 parts C.I. I. Direct Yellow 86 2 parts Diethylene glycol 10 parts Acetylenol EH (Surfactant from Kawaken Fine Chemicals) 1 part Water 84 parts (3) -M, C, Bk; C, M, B of recording ink (1)
Use the same dye as k and add the same amount, and add 10
Adjusted to be 0 copy. Recording Ink (4) Black pigment ink (4) was prepared by the following method. (Preparation of pigment dispersion) Styrene-acrylic acid-butyl acrylate copolymer (acid value 116, weight average molecular weight 3700) 1.5 parts Monoethanolamine 1 part Diethylene glycol 5 parts Water 81.5 parts

The above ingredients are mixed and mixed in a water bath to 70
Heat to 0 ° C to completely dissolve the resin. Carbon black prepared separately in this solution (MCF88, Mitsubishi Kasei)
After adding 10 parts and 1 part of isopropyl alcohol and premixing for 30 minutes, a zirconium bead having a diameter of 1 mm was used for a dispersion treatment for 3 hours, and then a centrifugal separation treatment (12000 rpm, 20 minutes) was performed to remove coarse particles. It was removed to obtain a dispersion.

(Preparation of Ink) Dispersion 10 parts Glycerin 3 parts Diethylene glycol 12 parts N-Methylpyrrolidone 7 parts Isopropyl alcohol 3 parts Carpol MH-50 (made by Asahi Denka, surfactant, polyoxyethylene (10) poly Oxypropylene (7) butyl ether) 1 part Water 64 parts

Recording liquid (4) was prepared by mixing the above components and adjusting the pH to 8 to 10 with monoethanolamine.

[0075]

[Table 1]

The recorded matter was evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0077]

[Table 2]

* Fixability of Example 4 was evaluated in the same manner as in the other examples, in which 100% of colorless liquid (D) and 200% of black ink were used.

** The bleeding evaluation of Example 4 was as follows.
Using the colorless liquid (D) and the yellow inks of the ink (4) and the ink (3), the bleeding at the boundary between the black ink and the yellow ink was evaluated in the same manner as in the other examples.

[0080]

As described above, by using the recording method of the present invention, it is possible to obtain a high-quality color image with high image density and high uniformity of image density on plain paper and no bleeding. At the same time, an image having good fixability and printing quality can be obtained.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a head portion of an inkjet recording apparatus.

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

FIG. 3 is an external perspective view of a head portion of the inkjet recording apparatus.

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.

FIG. 7 is a perspective view showing a recording unit in which a plurality of recording heads used in an embodiment of the present invention are arranged.

FIG. 8 is a perspective view of another recording head used in the present invention.

[Explanation of symbols]

 13 head 15 heat generating head 21 ink 25 recording material 28 heat generating head 40 ink bag 44 ink absorber 45 ink cartridge 61 wiping member 65 recording head 66 carriage 70 recording unit 71 head portion 71 atmosphere communicating hole

Claims (12)

[Claims] 1. An ink set comprising a colorless liquid and ink, wherein thickening occurs when the colorless liquid and the ink are mixed, or one component of the ink causes aggregation or precipitation, and paper. An ink set characterized in that the colorless liquid and the ink are adjusted so that the permeation rate into the ink and the colorless liquid are different. 2. The ink set according to claim 1, wherein the permeation rate of the ink into the paper is higher than that of the colorless liquid. 3. The ink set according to claim 1, wherein the ink is at least one color ink selected from black, cyan, yellow, magenta, red, green and blue. 4. The ink set according to claim 1, wherein the ink is composed of four colors of black, cyan, yellow and magenta. 5. The ink set according to claim 1, wherein the ink comprises three colors of cyan, yellow and magenta. 6. A method of forming a color image by applying a colorless liquid before or after applying the ink to a recording paper, wherein thickening occurs when the colorless liquid and the ink are mixed, or A method for forming a color image, characterized in that a colorless liquid and the ink are adjusted so that one component of the ink causes aggregation or precipitation and the permeation speed into the paper is different between the ink and the colorless liquid. 7. The method for forming a color image according to claim 6, wherein the penetration speed of the ink into the paper is higher than that of the colorless liquid. 8. The method for forming a color image according to claim 6, wherein the ink is at least one color ink selected from black, cyan, yellow, magenta, red, green and blue. 9. The method for forming a color image according to claim 6, wherein the ink is composed of four colors of black, cyan, yellow and magenta. 10. The method for forming a color image according to claim 6, wherein the ink comprises three colors of cyan, yellow and magenta. 11. The method for forming a color image according to claim 6, wherein the color image is formed by using an inkjet recording method. 12. The method for forming a color image according to claim 11, wherein the ink jet recording method is a method in which thermal energy is applied to ink to eject ink droplets.