JPH07148917A - Inkjet recording method - Google Patents

Abstract

(57) [Summary] [Object] To obtain an ink image on a recording medium at a low transfer pressure in a transfer type inkjet printer. Further, to obtain an ink image having high fixing strength and excellent fastness on a recording medium. A step of ejecting an ink containing at least water, an alkali-soluble resin, and an alkaline agent as an ink droplet from an ink recording head 2 to write an ink image 50 on a transfer drum 1, and transferring the ink image 50 to the transfer A step of volatilizing water and an alkaline agent on the drum 1, and the ink image 5
It comprises a transfer step of transferring 0 onto the recording paper 6 and a heating step of heating the ink image transferred onto the recording paper 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to recording in a transfer type ink jet printer which ejects ink droplets from a recording head to form an ink image on a transfer medium and then transfers the ink image onto the recording medium to obtain an ink image on the recording medium. Regarding the method.

[0002]

2. Description of the Related Art A conventional ink jet recording system of a type in which a recording image is written by ejecting ink droplets onto a recording medium is
Although the mechanism is simple and excellent in that noise is not generated, it has printing quality problems such as different printing conditions due to different recording media, for example, different paper quality of the transferred paper. In addition, there is a problem that the recorded image in an undried state is disturbed.

The apparatus proposed by the applicant of the present invention in Japanese Patent Laid-Open No. 62-92849 has been improved on the basis of the transfer type printer disclosed in US Pat. No. 4,538,156, and ink droplets have been improved. Is once ejected onto a transfer medium, where most of the water in the ink droplets is evaporated and the concentrated ink is transferred onto a recording medium such as paper. Further, in U.S. Pat. No. 5,099,256, a similar printer with improved print quality was proposed, which not only solves the above-mentioned problems but also enables extremely sharp image formation.

[0004]

However, the conventional recording method has the following two problems.

One of the problems is that in order to realize good transfer without transfer residue regardless of the print pattern, the pressing force of transfer becomes large. This problem will be described in detail below.

In the conventional recording method, as the concentration of the ink image progresses, the tackiness of the ink image decreases, so that a large transfer pressure is required when transferring the ink image onto the recording paper. Even in an actual recording apparatus using this recording method, transfer residue is not generated, and evaporation of the solvent component in the ink is promoted until suitable drying for obtaining a good printed matter. However, if the print patterns are different, the concentration state of the ink image will be different for each pattern. Regardless of such a difference in the concentration state of the ink image, in order to obtain good transferability, it is necessary to set the pressure value according to the maximum concentration state of the ink image, which requires a problematic pressure. I went away.

Another problem with the conventional recording method is that
That is, the robustness of the printed matter such as abrasion resistance and water resistance is insufficient.

In the conventional recording method using water-based ink, the colorant, resin, etc., which are the constituent components of the ink, are water-soluble or hydrophilic, and the ink image is printed on the recording medium. After being fixed, the ink image was disturbed by coming into contact with water again. Further, the mechanical strength of the dried ink component itself is weak, and the adhesive strength of the recording medium is also weak, so that the fixing strength of the ink image on the recording medium is weak and sufficient abrasion resistance cannot be obtained.

The present invention solves the above two problems. A first object of the present invention is to provide an ink jet recording method capable of realizing good transfer at a low pressure without the ink pattern concentration state being affected by the print pattern. It is an offer. A second object of the present invention is to provide a new ink jet recording method capable of obtaining an ink image having a high fixing strength on a recording medium, abrasion resistance, water resistance and excellent fastness. That is.

[0010]

According to the ink jet recording method of the present invention, an ink containing at least water, a coloring material, an alkali-soluble resin and an alkali agent is ejected as an ink droplet from a recording head to form an ink on a transfer medium. An image writing step, a step of volatilizing water and an alkaline agent on the transfer medium, a transfer step of transferring the ink image on the transfer medium to a recording medium, and an ink image transferred on the recording medium. The heating step of heating the ink, the step of volatilizing the alkaline agent and water from the ink image on the transfer medium consists of controlling the temperature of the transfer medium and the heating time of the ink image. Is added in a range from the neutralization equivalent of the alkali-soluble resin to 1.5 times the neutralization equivalent, the temperature of the transfer medium is 60 ° C. to 170 ° C., and heat is applied to the ink image. Time Waru is characterized in that 0.1 to 40 seconds.

[0011]

In the ink jet recording method of the present invention using an ink containing at least water, a coloring material, an alkali-soluble resin and an alkali agent, in the step of volatilizing water and the alkali agent from the ink image on the transfer medium, When the water and the alkaline agent are volatilized, the alkali-soluble resin, which has been in the dissolved state until then, comes to be in a precipitated state. In this state, the ink image has an adhesive force to the recording medium. In order for the ink image to have good transferability without being affected by the print pattern, it is necessary for the ink image to have a uniform adhesive force until the transfer is completed. For this reason, the alkaline agent has a boiling point of 100 ° C. or higher, and the amount added to the ink is within a specific range, and / or the temperature of the transfer medium is 60 ° C. to 170 ° C. and the heating time of the ink image is 0. When the ink image is heated for 1 to 40 seconds, the evaporation amount of the alkaline agent for precipitating the resin becomes a preferable range, and the ink image maintains an adhesive force that enables good transfer from the transfer medium to the recording paper at low pressure. You can do it.

Further, since the binder component of the ink is poorly water-soluble or water-insoluble, it is possible to obtain a printed matter having excellent water resistance.

Further, the step of transferring the ink image from the transfer medium to the recording medium is performed by infiltrating the semi-dry alkali-soluble resin in the ink image into the recording medium. In the step of heating the ink image on the recording medium, completely drying the alkaline agent from the ink image makes it possible to obtain an ink image having good abrasion resistance.

When the boiling point of the alkaline agent is 100 ° C. or lower, the ink image is excessively dried on the transfer medium, and transfer at a low pressure cannot be performed. Further, the alkaline agent has an effect of suppressing excessive drying of the ink in the ink ejection head, like the water-soluble organic solvent, but a solvent which is lower than the boiling point of water and easily volatilizes easily becomes clogged.

If the amount of the alkali agent added is less than the neutralization equivalent, the alkali-soluble resin cannot be dissolved stably, clogging occurs in the ink discharge head, and the addition to the ink is moderate. Exceeding 1.5 times the equivalent weight, although the exact reason is not clear, since an alkaline agent remains in the ink image formed on the transfer medium, a proper dry state cannot be obtained and the transfer pressure of the ink image is not obtained. Grows larger.

Further, in order to bring the ink containing the alkali-soluble resin of the present invention and the alkali agent into a preferable dry state, the temperature is preferably 60 ° C. to 170 ° C. and 0.1 second to 40 seconds. The transfer medium at 60 ° C., which is the minimum value of thermal energy for drying the applied ink image, has a density of 0.
If the time is less than 1 second, the alkaline agent remains in the ink image formed on the transfer medium, so that a proper dry state cannot be obtained and the transfer pressure of the ink image onto the recording paper increases. Furthermore, when the temperature of the transfer medium exceeds 170 ° C. and exceeds the range of 40 seconds as the condition that the thermal energy becomes the maximum, the ink image is excessively dried on the transfer medium, and the ink image at a low pressure is reached. Can no longer be transferred to the recording paper.

[0017]

EXAMPLES First, examples of the ink jet recording method of the present invention will be described in detail.

FIG. 1 is a perspective view showing the structure of a transfer type ink jet printer to which the ink jet recording method of the present invention is applied.

Around the transfer drum 1 which is a transfer medium, an ink jet recording head 2, a backup roller 3 which is a transfer means, and a cleaner 8 for removing deposits on the transfer drum are sequentially installed from the upstream side in the rotational direction. It is arranged. A first heating unit 7 is arranged inside the transfer drum 1 between the recording head 2 and the backup roller 3 and further heats the ink image transferred onto the recording paper 6 which is a recording medium. The heating means 9 is arranged in the movement path of the recording paper 6.

The recording head 2 is an ink jet recording head of the type using a piezoelectric element, and has a plurality of nozzles in the axial direction of the transfer drum 1. An ink tank 21 is connected to the inkjet recording head 2 and ink is supplied as necessary.

The transfer drum 1 is formed by laminating an elastic layer 12 made of silicone rubber around a metal tube 11. A rubber material is suitable for the elastic layer 12, and among them,
It is desirable to use a material having a good mold release property that easily peels off the ink image, and having heat resistance and durability, and silicone rubber, fluororesin, fluorosilicone rubber or the like, or a modified product thereof is preferable.

Further, the elastic layer 12 may be formed by coating various surface materials (ink layer supporting surfaces) of the various rubber materials with various releasing agents. As the coating material, a silicone coating or a fluorine coating is preferable.

The backup roller 3 is a metal roller made of aluminum, and is structured so that it can be pressed and released from the transfer drum 1 by a transfer pressure applying device (not shown). During pressing, the recording paper 6 is rotated in the direction of arrow B in the figure at the same speed as the peripheral speed of the transfer drum 1. The transfer load is
It can be adjusted between 0.6 kg weight / cm and 1.5 kg weight / cm.

The cleaner 8 is made of felt,
The transfer drum 1 is contacted with a predetermined pressure by a contact mechanism (not shown).

FIG. 2 is a diagram showing the construction of a transfer type ink jet printer to which the ink jet recording method of the present invention shown in FIG. 1 is applied.

The first heating means 7 is, as shown in FIG.
The halogen lamp 1 includes a rod-shaped halogen lamp 15 and a reflector 16 having an elliptical surface as an inner surface.
The heat energy of No. 5 is arranged so as to be collected at one point by the reflector 16.

The second heating means 9 includes a heat roll 4 and a pressure roll 3 which incorporate heating means such as a ceramic heater.
0 and the recording paper 6 is the heat roll 4
It is guided by a guide plate (not shown) so as to pass through the nip portion formed by the pressure roll 30 and the pressure roll 30.

The ink used in the recording method of the present invention comprises at least water, a coloring material, an alkali-soluble resin, an alkali agent and water.

Specifically, Table 1 shows examples of the ink of the present invention.
In addition, the ink manufacturing method of the ink examples 2 to 5 is the same as the ink example 1
The same method was used.

[0030]

[Table 1]

A method for manufacturing Ink Example 1 will be illustrated.

Preparation of 15% carbon black aqueous dispersion.

MA-100 (manufactured by Mitsubishi Kasei Co., Ltd.) was added to carbon black as a dispersant containing sodium dioctyl sulfosuccinate dissolved in pure water at a pigment ratio of 0.2, and dispersed with a ball mill to an average particle size of 0.5 μm. did. To this dispersion, a solution of an alkali-soluble resin dissolved in water containing an alkaline agent is added, and then a water-soluble organic solvent is added,
Mix and stir for another 30 minutes to mix completely. It was filtered with a membrane filter having a pore size of 10 μm to remove dust and coarse particles, and a recording ink was obtained.

Next, the operation of the ink jet recording method according to the first embodiment of the present invention will be described.

First, the ink image writing process will be described.

The ink image writing process will be described with reference to FIG. FIG. 3 is a diagram showing how an ink image is written by the inkjet recording head 2 used in the embodiment of the present invention. The recording head 2 used in this embodiment is a line-shaped recording head having nozzles over the entire printing area L, and one rotation of the transfer drum 1 writes an ink image for one page. Ink droplets are selectively ejected from the nozzles of the recording head 2 according to a recording signal to form a desired ink image 50.

Next, the ink image 50 formed by the ink jet recording head 2 on the transfer drum 1 is heated by the first heating means 7. The first heating means 7 can be set to an arbitrary value of 40 ° C. to 180 ° C. by a temperature detector (not shown), and in the present Example 1, it was set to 60 ° C. The ink image on the transfer drum 1 is heated to increase the solid content concentration and form a sticky film.

In this state, the ink image itself is not affected by the degree of concentration and retains sufficient adhesiveness to the recording medium. For this reason, the heating amount of the first heating means 7 is set to a heating amount so that the ink image continues to have a sufficient adhesive force to the recording medium until the completion of the transfer of the ink image by evaporating the water content and the alkaline agent. did. In the evaluation of the examples and comparative examples of the present invention, the time for which thermal energy is applied to the transfer medium can be changed. For Example 1, the ink image was 0.
Heated for 1 second.

Next, the transfer drum 1 and the backup roller 3
The recording paper 6 is passed through the abutting portion of the recording paper 6 and the applied pressure to transfer the ink image 50 on the transfer drum 1 to the recording paper 6. At this time, since the ink image has a uniform adhesiveness, it is not necessary to set the transfer pressure in the maximum concentrated state. Therefore, a high-quality image can be obtained on the recording paper 6 with a low pressure.

Here, the low pressure means 1 kg weight / weight in order to downsize the apparatus, reduce the cost of components such as the transfer drum 1 and the backup roller 3, and further improve the durability of the elastic layer on the surface of the transfer drum. cm or less, more preferably 0.6 kg weight / cm or less.

The ink image pressure-transferred onto the recording paper 6 is
By evaporating the alkaline agent contained in the ink by the second heating means 9, an ink image insoluble in water (the alkali-soluble resin used in the present invention is dissolved in an alkaline solution but is dissolved in water). In contrast, it is insoluble or insoluble).

When an emulsion resin is added as a resin component as in Ink Example 5, the emulsion resin is heated to a softening temperature or a film forming temperature or higher.

In this embodiment, since the softening temperature of the emulsion resin contained in the ink is 80 ° C., the heating temperature of the second heating means 9 is set to 150 ° C.

As described above, since the ink image 50 is heated by the second heating means 9 and the water, the alkaline agent and the water-soluble organic solvent contained in the ink are completely volatilized, the ink image 50 has excellent fastness. An ink image can be obtained on the recording paper 6.

When the transfer drum 1 completes the transfer of the ink image to the recording paper 6, it moves to a portion in contact with the cleaner 8 as it rotates, and the residual ink on the transfer drum 1 is removed.

Next, specific composition examples of the ink applicable to the above-mentioned embodiment of the present invention will be shown.

As the solvent for ink, water is mainly used because of its low viscosity, excellent safety, easy handling, low cost, and no odor. As the ink material, pure water or ultrapure water that has undergone a purification process such as ion exchange or distillation is desirable.

A hydrophilic high-boiling point low-volatile solvent is added to the present ink in order to impart the effects of nozzle clogging resistance, moisture retention and dispersion stability. Examples of the hydrophilic high-boiling point low-volatile solvent used in the present ink include glycerin, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, hexylene glycol, polyethylene glycol,
A water-soluble organic solvent such as a high boiling point and low volatility polyhydric alcohol such as polypropylene glycol can be added within a range in which the flow of printing does not cause bleeding.

A pigment is used as the coloring agent, and any pigment having a good affinity with water as a main solvent or one capable of being uniformly dispersed by the combined use of a dispersant or the like can be used.

Examples of pigments that can be used in the present ink include organic pigments and inorganic pigments. For black, carbon black (C.I., such as furnace black, lamp black, acetylene black, channel black) can be used. ．Pigment black 7) type or copper,
Examples include metals such as iron (CI Pigment Black 11) and titanium oxide, and organic pigments such as aniline black (CI Pigment Black 1). For color, C.I. I. Pigment Yellow 1 (Fast Yellow
G), 12 (this as yellow AAA), 83 (this as yellow HR),
C. I. Pigment Red 22 (Brilliant First Scarlet), 48: 2 (Permanentlet 2B (Ba)), 57: 1 (Brilliant Carmine 6B), 81 (Rotamine 6G Rake), 122 (Quinacrydon Magenta), C.I. I. Pigment Blue 15 (Phthalocyanine Blue
R), 15: 3 (phthalocyanine blue G), 15: 6 (phthalocyanine blue)
E) etc. can be used. Further, processed pigments such as graft carbon whose surface is treated with a resin can be used. The amount added is preferably 0.5 to 30% by weight,
Further, 1.0 to 12% by weight is preferable. Grain diameter is 25μ
A pigment having a particle size of 1 μm or less is used, and a pigment having particles of 1 μm or less is preferably used.

In order to uniformly disperse these colorants,
If necessary, the dispersant can be added to the pigment in an amount of 0.5 to 200 wt%, and more preferably 1 to 50 wt%,
Particularly preferably, it can be added in an amount of 5 to 30 wt%, and it is desirable to carry out dispersion treatment with a ball mill or the like.

The alkali-soluble resin used in the present ink is preferably a resin obtained by polymerizing a hydrophobic addition-polymerizable monomer and α, β / ethylenically unsaturated carboxylic acid.

The hydrophobic addition-polymerizable monomer is a monomer selected from acrylic acid, styrene, ethylene, vinyl chloride, and derivatives thereof, and α, β-ethylenically unsaturated carboxylic acid is acrylic acid, itaconic acid, fumar. It is selected from acids, maleic anhydride and its derivatives.
The preferred molecular weight of this resin is up to 50,000, more preferably 30,000 or less. The acid value is preferably 50 to 250.

Resins exceeding this range are insoluble in the solvent and cannot secure the stability of the ink, or dissolve in the solvent without the addition of an alkaline agent, so that the water resistance of the recorded image is secured. I can't.

The alkali-soluble type resin may be one kind or two kinds.
A mixture of two or more species can be used. The amount added is
The resin: colorant ratio is preferably in the range of 1: 0.1 to 0.2: 1. However, as the addition amount is increased, the ink viscosity is also increased. Therefore, it is preferable to suppress the addition amount to about 30% by weight with respect to the entire ink.

In the present invention, a thermoplastic resin may be added depending on the case. Specific examples thereof include styrene-butadiene copolymer, crosslinked acrylic resin, crosslinked styrene resin, polyolefin resin, styrene-acrylic copolymer, styrene-methacrylic copolymer, polystyrene, styrene-acrylamide copolymer, n- Examples thereof include isobutyl acrylate, acrylamide, rosin-based resin, polyethylene, polyvinyl alcohol, cellulose-based resin, epoxy resin, ethylene-vinyl acetate copolymer, and vinyl acetate-acrylic copolymer, but are not limited thereto.

The above resins are preferably added in the form of emulsion particles which are stabilized and dispersed in water.
Further, although these resins dry under a normal temperature environment, it is desirable that they do not form a film and form a powder or a brittle solid.

Furthermore, it is desirable to form a strong and water-resistant film when heated above the softening temperature, melting temperature, or film-forming temperature.

Further, the ink is made to have a low surface tension, the wettability to a transfer medium made of a rubber material having a low surface tension is improved, the repulsion and the flow of the ink on the ink image transfer medium are prevented, and the ink image is fixed. Therefore, one or more kinds of water-soluble anionic and nonionic surfactants are added.

The amount added is 0.05 to 10 wt%, preferably 0.1 to 8 wt% to ensure sufficient wettability.
is necessary.

Examples of anionic surfactants include higher fatty acid salts, higher alkyl dicarboxylic acid salts, higher alcohol sulfuric acid ester salts, higher alkyl sulfonates, polyoxyethylene alkylphenyl ether sulfates, and the like, but are not limited thereto. Not something.

Fluorine-based nonionic surfactants,
Examples include, but are not limited to, silicone type, acrylic acid copolymer, polyoxyethylene alkyl ether, and polyoxyethylene alkylphenyl ether.

In addition, if necessary, a pH adjusting agent such as potassium dihydrogen phosphate, disodium hydrogen phosphate, fungicide,
Benzoic acid, dichlorophen, hexachlorophene, sorbic acid, p-hydroxybenzoic acid ester, ethylenediaminetetraacetic acid (EDTA), sodium dehydroacetate, 1,2-bezothiazolin-3-one, 3, for the purpose of antiseptic and rust prevention. 4-isothiazolin-3-one and the like can be included.

Further, urea, thiourea, ethylene urea and the like can be added for the purpose of preventing nozzle drying.

As for the physical properties of the ink, in order to ensure stable ejection from the head and stable ink supply to the head, 50
It is preferably mPa · sec or less, and more preferably 25 mPa · sec or less. Each of the ink composition examples described below was adjusted to have a viscosity within this range.

Table 2 shows the temperatures of the ink and the transfer medium of Examples 1 to 40 and the time for which heat is applied to the ink image according to the ink jet recording method of the present invention.

[0067]

[Table 2]

Inks 6 to 14 as comparative examples of the present invention are shown in Tables 3 and 4. Ink examples 6 to 9 and 11 to 14
The ink manufacturing method was the same as the ink example 1.

Ink Example 6 is an ink example in which an alkaline agent having a boiling point of 100 ° C. or less was added in an amount of 1.3 times the neutralization equivalent of the alkali-soluble resin.

Ink example 7 is an ink example in which an alkaline agent having a boiling point of 100 ° C. or higher was added in an amount of 1.6 times the neutralization equivalent of the alkali-soluble resin.

Ink Example 8 is an ink example in which an alkaline agent having a boiling point of 100 ° C. or higher was added in an amount of 1.8 times the neutralization equivalent of the alkali-soluble resin.

Ink Example 9 is an ink example in which an alkaline agent having a boiling point of 100 ° C. or higher is added in an amount of 2.0 times the neutralization equivalent of the alkali-soluble resin.

Ink example 11 is an ink in which the same emulsion as in ink example 1 is added to the ink and an alkaline agent at 100 ° C. or lower is added in an amount 1.3 times the neutralization equivalent.

Ink examples 12 to 13 are 1.6 times the addition amount of the alkaline agent having a boiling point of 100 ° C. or higher, respectively, and 1.8.
This is an example of an ink added at 2 times and 2.0 times.

[0075]

[Table 3]

[0076]

[Table 4]

Table 5 shows the temperatures of the ink and the transfer medium of Comparative Examples 1 to 22 and the time for which heat is applied to the ink image according to the ink jet recording method of the present invention.

[0078]

[Table 5]

Ink Example 10 is US Pat. No. 4,538.
It is a composition example produced based on the conventional example described in the specification of No. 156.

As Comparative Example 23 of the present invention, a conventional transfer type ink jet printer having the structure shown in FIG. 4 was used. In FIG. 4, an inkjet recording head 202 having a plurality of nozzles is provided on a cylindrical transfer medium 201 with a gap therebetween. The plurality of nozzles are arranged at predetermined intervals in the rotation axis direction of the transfer medium 201, and the recording head 202
Can move in this direction. The transfer medium 201 is heated by the heating unit 205, and the surface temperature of the transfer drum is controlled by a temperature detector (not shown) so as to be within a predetermined temperature range. To form an ink image on the transfer medium 201, the recording head 202 is moved in the rotation axis direction of the transfer medium 201 while continuously rotating the transfer medium 201 to eject ink, and an ink image is formed for each ring-shaped region. 1
After forming a page of ink image and the ink is concentrated,
The ink image is transferred onto the recording medium 203 by bringing the recording medium 203 into contact with the transfer medium 201 and pressing it with the pressure roller 204. The major difference between the example of the present invention and the comparative example is that there is no heating means for heating the ink image on the recording medium.

The following inks were used in the examples and comparative examples of the transfer type ink jet recording method of the present invention.
The results of a printing test on Xerox 4024 paper are shown below.

The evaluation items are 1. The relationship between the transfer pressure and the transfer efficiency when transferring an ink image, and the robustness of printed matter 2. Abrasion resistance, 3. Water resistance was evaluated for three items.

The respective evaluation conditions and criteria are as follows.

1. Relationship between transfer pressure and transfer efficiency Solid printing pattern 1 dot continuous line, transfer pressure 0.6kg weight / cm: Easy downsizing of equipment and cost reduction of parts 1.0kg weight / cm: Downsizing of equipment and cost reduction of parts 1 .5 kg weight / cm: Difficulty in downsizing of equipment and cost reduction of parts Transfer efficiency ○: Transfer efficiency is 100% and transfer is not caused, and image is not deformed Δ: Transfer efficiency is 95 to 100%, transfer is partially left, and image is deformed X: Transfer efficiency is less than 95%, clear density change, white spots,
Image deformation occurs 2. Scratch resistance (1 minute after printing) ◯: No ground stain even if rubbed strongly with finger Δ: Ground stain observable when visually rubbed strongly with finger ×: Visually touched even with light finger A stain that can be identified is generated. Water resistance ○: The printed matter does not bleed at all even if the printed matter is dripped. Δ: The edges are blurred when the printed matter is dripped. ×: The printed matter flows when the printed matter is dripped. Examples 1 to 4 based on the above evaluation conditions and judgment criteria
0 and Comparative Examples 1 to 23 show the results of the investigations shown in Tables 6 and 7.

[0085]

[Table 6]

[0086]

[Table 7]

As shown in the above table, the recording method of the present invention, which uses an ink containing at least water, a coloring material, an alkali-soluble resin and an alkali agent, has a transfer efficiency of 100 regardless of the print pattern at a low transfer pressure. %, And sufficient robustness of the printed matter was obtained.

On the other hand, in the case of using the recording method of the comparative example, at a low transfer pressure, there was a difference in transfer efficiency depending on the time from printing to transfer and the print pattern, and good transfer efficiency was not obtained. Moreover, in order to improve the transfer efficiency, an excessive transfer pressure is required. Furthermore, it was not possible to obtain sufficient performance in terms of the robustness of the printed matter.

From the above results, in the ink jet recording method of the present invention, by containing the adhesive component in the ink and evaporating the water content and the alkaline agent in the ink image on the transfer medium, the time until the completion of the transfer is reduced. Since a uniform adhesive ink image can be obtained, a novel effect that an ink image can be transferred to a recording medium at a low pressure regardless of a printing pattern can be obtained.

The step of transferring the ink image from the transfer medium to the recording medium is carried out by allowing the alkali-soluble resin in the semi-dry state in the ink image to penetrate into the recording medium, and is therefore the next step. In the heating process of the ink image on the recording medium, if the alkaline agent is completely dried from the ink image,
An ink image with high fixing strength could be obtained.

In addition, in the ink jet recording method of the present invention, since the ink image is transferred onto the recording medium and then the heating step is performed, in addition to the above effects, sharpening of edges, rough paper and other plain paper compatibility can be achieved. It is possible to improve the dryness and quick-drying property.

Further, according to the present invention, since a plurality of inks can be overlaid on the transfer medium, a two-color printer,
It can also be applied to multi-color printers and full-color printers.

[0093]

As described above, according to the ink jet recording method of the present invention, an ink containing an alkali-soluble resin is contained in the ink, and the water and the alkaline agent in the ink image are evaporated on the transfer medium to form an ink image. By obtaining an ink image having a uniform adhesiveness within the time until the transfer is completed, there is an effect that the ink image can be transferred to the recording medium at a low pressure regardless of the print pattern.

Further, the step of transferring the ink image from the transfer medium to the recording medium is carried out by allowing the alkali-soluble resin in the semi-dry state in the ink image to penetrate into the recording medium, which is the next step. In the heating process of the ink image on the recording medium, if the alkaline agent is completely dried from the ink image,
It has an effect that an ink image having high fixing strength can be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view showing a configuration of an inkjet printer according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a configuration of an inkjet printer according to an embodiment of the present invention.

FIG. 3 is a diagram showing how an ink image is written by an inkjet recording head used in an example of the present invention.

FIG. 4 is a schematic view of a conventional transfer type inkjet printer used for evaluation of Comparative Example 23 of the present invention.

[Explanation of symbols]

 1: Transfer drum (transfer medium) 2: Inkjet recording head 3: Backup roller 4: Heat roll 5: Ink image 6: Recording paper (recording medium) 7: First heating means 8: Cleaner 9: Second heating means 15: Rod-shaped halogen lamp 16: Reflector 21: Ink tank 30: Pressure roll 201: Cylindrical transfer medium 202: Recording head 203: Recording medium 204: Pressure roller 205: Heating means

Claims (1)

[Claims] 1. A step of discharging an ink containing at least water, a coloring material, an alkali-soluble resin and an alkali agent as an ink droplet from a recording head to write an ink image on a transfer medium, and the step of writing the ink image on the transfer medium. On the transfer medium, which comprises a step of volatilizing water and an alkaline agent above, a transfer step of transferring the ink image on the transfer medium to a recording medium, and a heating step of heating the ink image transferred on the recording medium. The step of volatilizing the alkaline agent and water from the ink image of consists of controlling the temperature of the transfer medium and the heating time of the ink image,
The content of the alkaline agent in the ink is added in the range from the neutralization equivalent of the alkali-soluble resin to 1.5 times the neutralization equivalent, and the temperature of the transfer medium is 60 ° C to 170 ° C.
An ink jet recording method is characterized in that heat is applied to the ink image for 0.1 to 40 seconds.