JP2003266663A - Image recording method and ink jet printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image recording method and an ink jet printer in which an image quality similar to that of photograph can be attained by enhancing fading properties of ink. <P>SOLUTION: In the image recording method, an image is recorded while jetting ink of each color from each line head 11 onto a recording medium F having an ink absorbing layer on a support and containing thermoplastic resin in the surface layer while fixing the order of overcoating a plurality of colors at all times. Subsequently, the recording medium is hot pressed at a fixing section 50 such that an image being formed on the recording medium has a mapping value of 60%-95% thus performing image recording. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image recording method and an ink jet printer capable of forming an image having image quality and storability comparable to those of a photograph.

[0002]

2. Description of the Related Art In recent years, image processing technology using ink jet printers has improved the sharpness and granularity of pixels by reducing the size of ink droplets to be printed, head scanning, and higher precision of conveyance of recording paper. Efforts are being made to approach image quality. For example, by recording an image with dye ink using resin-coated paper used for photographic printing paper and provided with an ink absorption layer, it has become possible to obtain image quality comparable to silver halide photography. .

Image quality is an important performance for photographs that have been traditionally used as a means of expressing images.
It cannot be expressed by evaluation scales such as sharpness, graininess, and glossiness, and even if these numerical values were simply improved, it was different in appearance from the silver salt photograph, and was visually different. Also, in the photo, the balance of the gray part such as wedding dress is important,
When gray was made with a mixed color of YMC, the balance was easily lost, and when gray was made with K, the graininess was sometimes deteriorated. Further, since the respective inks have different color fading properties, there is a possibility that the gray balance may be lost during printing and after the image is stored. Furthermore, K ink is often made by mixing YMC color materials, and the gray balance may be lost due to fading.

[0004]

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, the present invention provides an image recording method and an ink jet printer capable of improving the fading property of ink and obtaining an image quality comparable to that of a photograph. The purpose is to

[0005]

In order to achieve the above object, the first image recording method according to the present invention is directed to a recording medium having an ink absorbing layer on a support and a thermoplastic resin on the surface layer. An image is recorded by ejecting the inks of the respective colors so that the overlapping order of the plurality of colors is always the same, and then the image clarity value of the image formed on the recording medium is 60% or more and 95%.
Image recording is performed by heating and pressurizing the recording medium as described below.

According to the first image recording method, the order in which the respective colors are overlapped is always the same, so that the colors reproduced by the respective inks are constant without any variation, the color reproducibility is improved, and a plurality of colors are reproduced. When gray is created by superimposing color inks, it is difficult to lose the gray balance. In addition, since the thermoplastic resin of the surface layer is melted and covers the recording medium by heating and pressurizing the recording medium after the image recording, the image clarity value is improved and the color fading property is improved, and the gray level during image storage is improved. It is possible to prevent the balance from being lost. Furthermore, by heating and pressurizing the recording medium so that the image clarity value becomes 60% to 95%, the glossiness of the image quality is similar to that of a photograph, and a photograph-like texture can be obtained.

In the above-mentioned first image recording method, it is preferable that the inks of the respective colors are ejected in the order of the color having the lower lightness, and the color having the lower lightness is first and the color having the higher lightness is reproduced later. The range of sex becomes wide.

When each of the plurality of colors includes each color of YMC, it is preferable to eject the ink of each color in the order of M, C, Y or in the order of C, M, Y. If you make gray with YMC, graininess will improve, and if you follow the above order,
Gray balance is less likely to collapse.

In the second image recording method according to the present invention, each color containing two or more kinds of K ink having different densities with respect to a recording medium having an ink absorbing layer on a support and containing a thermoplastic resin on the surface layer. Image is recorded by ejecting the above ink and the image clarity value of the image formed on the recording medium thereafter is 60%.
Image recording is performed by heating and pressurizing the recording medium to 95% or less.

According to the second image recording method, by forming an image with each color ink containing two or more kinds of K inks having different densities, the graininess of gray is improved, and in particular, the gray color of light color is improved. Good graininess. In addition, since the thermoplastic resin of the surface layer is melted and covers the recording medium by heating and pressurizing the recording medium after the image recording, the image clarity value is improved and the color fading property is improved, and the gray level during image storage is improved. It is possible to prevent the balance from being lost. Furthermore, the image clarity value is 60%
By heating and pressurizing the recording medium so that the content becomes ˜95%, the glossiness of the image quality is similar to that of a photograph, and the texture like a photograph can be obtained.

In the above-mentioned first and second image recording methods,
At the time of heating and pressurizing the recording medium, the image clarity value can be set to 60% or more and 95% or less by controlling at least one of the heating temperature, the pressing force, and the heating / pressurizing time. The image clarity value can be controlled by the constitution of the recording medium, the type and content of the thermoplastic resin particles, the heating / pressing method, the smoothness of the surface in contact with the medium during heating / pressing, and the like.

It is preferable that the surface layer of the recording medium further contains an inorganic pigment. In addition, the above-mentioned first and second
In the image recording method, the ink may be either dye ink or pigment ink. Dye ink is particularly preferable because it has good color reproducibility, and fading can be improved by the method of the present invention. Further, in the case of a pigment ink, the image storability (not browning or bleeding) is particularly preferable, and the gloss and texture can be improved by the method of the present invention.

A first ink jet printer according to the present invention comprises an ink head for ejecting a plurality of inks onto a recording medium, and a heating / pressurizing means for heating and pressurizing the recording medium after ejecting the inks, An inkjet printer for recording an image on the recording medium, wherein the order of overlapping of a plurality of colors is always the same with respect to the recording medium having an ink absorbing layer on a support and containing a thermoplastic resin on the surface layer. Ink of each color is ejected from the ink head, and the image clarity value of the image formed on the recording medium thereafter is 60.
It is characterized in that the recording medium is heated and pressurized by the heating and pressurizing unit so that the recording medium becomes not less than 95% and not more than 95%.

According to the first ink jet printer,
Since the above-described first image recording method can be executed and the order in which the respective colors are overlapped is always the same, the colors reproduced by the respective inks are constant without any variation, the color reproducibility is improved, and the plural colors are reproduced. When creating gray by superimposing ink, it is difficult for the gray balance to collapse. In addition, since the thermoplastic resin of the surface layer is melted and covers the recording medium by heating and pressurizing the recording medium after the image recording, the image clarity value is improved and the color fading property is improved, and the gray level during image storage is improved. It is possible to prevent the balance from being lost. Furthermore, the image clarity value is 60
By heating and pressurizing the recording medium so as to be in the range of% -95%, the glossiness of the image quality is similar to that of a photograph, and a texture like a photograph can be obtained.

In this case, it is preferable that the inks of the respective colors are ejected in the order of low lightness, and when the plurality of colors include the respective colors of YMC, the order of M, C, Y or C, M, It is preferable to eject the inks of the respective colors in the order of Y.

A second ink jet printer according to the present invention comprises an ink head for ejecting a plurality of inks onto a recording medium, and a heating / pressurizing means for heating and pressurizing the recording medium after ejecting the inks, An ink jet printer for recording an image on the recording medium, comprising two or more kinds of K ink having different densities from the ink head with respect to the recording medium having an ink absorption layer on a support and a thermoplastic resin on the surface layer. An ink of each color including is recorded to record an image, and then the recording medium is heated by the heating and pressurizing unit so that the image clarity value of the image formed on the recording medium is 60% or more and 95% or less. And pressurizing.

According to this second ink jet printer, the above-mentioned second image recording method can be executed,
By forming an image with each color ink containing two or more types of K inks having different densities, the graininess of gray is improved, and particularly the graininess of light gray is improved. In addition, since the thermoplastic resin of the surface layer is melted and covers the recording medium by heating and pressurizing the recording medium after the image recording, the image clarity value is improved and the color fading property is improved, and the gray level during image storage is improved. It is possible to prevent the balance from being lost. Furthermore, by heating and pressurizing the recording medium so that the image clarity value becomes 60% to 95%, the glossiness of the image quality is similar to that of a photograph, and a photograph-like texture can be obtained.

Further, the heating / pressurizing means of the first and second ink jet printers controls at least one of heating temperature, pressure and heating / pressurizing time when the recording medium is heated and pressed. Can be configured. The image clarity value can be controlled by, for example, the configuration of the recording medium, the type and content of the thermoplastic resin particles, the heating / pressing method, the smoothness of the surface in contact with the medium at the time of heating / pressing.

The image clarity is an important factor for determining the aesthetic factor of an image as an index of how sharply an image is projected on a surface of a coating film and without distortion. It is a characteristic value. As a method for measuring the image clarity value, for example, there is a method defined in JIS H8686, in which an optical device is used, and the image clarity is obtained as the image clarity from the waveform of the light quantity obtained through the optical comb. There are various types of optical combs having a dark / light ratio of 1: 1 and widths of 0.125, 0.5, 1.0 and 2.0 mm. For the measurement, the optical comb is moved, the maximum waveform (M) and the minimum waveform (m) on the recording paper are read, and the image definition is obtained by the following formula.

C = (M−m) / (M + m) × 100 where C is the image definition (%), M is the highest waveform, and m is the lowest waveform.

The image sharpness C is an index indicating that the larger the value, the better the image clarity, and the smaller the value, the "blur" or "distortion". If the "blur" or "distortion" of this image is small, Even if the gloss values on the gloss meter are the same, the glossiness by appearance becomes strong.

The ink head of the above-mentioned ink jet printer may be of the on-demand type or the continuous type. Further, as a discharge (injection) method, an electro-mechanical conversion method (for example, a single cavity type, a double cavity type, a bender type, a piston type, a shear mode type, a shared wall type, etc.), an electric-heat conversion method ( Specific examples include a thermal inkjet type, a bubble jet (registered trademark) type, an electrostatic suction type (for example, an electric field control type, a slit jet type, etc.), and a discharge type (for example, a spark jet type). However, any ejection method may be used.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION The first and second embodiments of the present invention will be described below.
Embodiments will be described with reference to the drawings.

<First Embodiment>

FIG. 1 is a conceptual view of an ink jet printer according to the first embodiment, and FIG. 2 is a perspective view schematically showing the ink head of FIG.

As shown in FIG. 1, the ink jet printer according to the present embodiment has a roll body 9 in which a long sheet-shaped recording medium F is wound in a roll shape, and is pulled out from the roll body 9 in a transport direction S. A recording section 10 having a serial head 6 for ejecting ink of each color onto the recording medium F to write an image and a platen 12 arranged to face the serial head 6 via the recording medium F, and an image is written. Cutting unit 4 for cutting the encased recording medium F into a predetermined size
0, a fixing unit 50 that fixes the image by heating and pressurizing the cut recording medium F, and a discharge storage unit 60 that discharges and stores the recording medium F on which the image is fixed are in the transport direction S. It is located from the upstream side.

An accumulation unit 18 is provided between the recording unit 10 and the cutting unit 40 so as to adjust the cutting timing in the cutting unit 40, and the recording medium F is conveyed upstream and downstream of the accumulation unit 18. A pair of conveying rollers 15a and 15b for arranging the conveying rollers are arranged. The accumulation unit 18 has a sensor 1 for detecting the accumulation amount of the recording medium F.
9 is provided. Further, the pair of transport rollers 16 a and 16 b for transporting the cut recording medium F is provided in the fixing unit 50.
Are arranged on the upstream side and the downstream side.

The cutting unit 40 moves the recording medium F in a predetermined position in a direction B indicated by an arrow in order to detect the front end of the conveyed recording medium F and a detection sensor 41 arranged upstream thereof. And a cutting member 42 that cuts to the size. The cutting member 42 is driven in the direction B and the opposite direction by the cutting portion drive mechanism 25 (FIG. 4).

Next, the serial head 6 shown in FIG. 1 will be described. As shown in FIGS. 1 and 2, the serial head 6
Is a large number of nozzles 1a in the vertical direction of the drawing on the nozzle surface
Are arranged in a row to form nozzle rows 6a, 6b, 6c, and the nozzle surfaces 7 are spaced so as to face the recording medium F.
The serial head 6 is configured to move in the main scanning direction T that is substantially orthogonal to the extending direction of the nozzle rows 6a to 6c, and performs main scanning in the direction perpendicular to the paper surface of FIG. The serial head 6 has nozzle rows 6a to 6c arranged in the order of M, C, and Y, and moves each ink in the main scanning direction T by M,
By ejecting the ink onto the recording medium F in the order of C and Y, a color image can be formed on the recording medium F.

Each of the nozzles 1a of the nozzle rows 6a to 6c of the serial head 6 is composed of a piezo element that is sheared and deformed by the application of a drive signal, and the ink is sheared and deformed according to the voltage level of the input drive signal. An image can be written on the recording medium by ejecting.

The serial head 6 shown in FIG. 2 may be configured like the serial head 8 shown in FIG. The serial head 8 has three nozzle rows added to the nozzle surface 7 and has nozzle rows 8a to 8f, and the nozzle rows 8a to 8f are MCY.
The inks are arranged in the order of YCM, and each ink can be ejected in the order of M, C, and Y while moving in the main scanning direction T and the opposite direction.

Next, the fixing unit 50 of FIG. 1 will be described with reference to FIGS. 1 and 3. FIG. 3 is a front view showing the fixing unit of FIG. 1 in detail. The fixing unit 50 in FIGS. 1 and 3 includes a heating roller 51 that heats the recording medium F, a pressure roller 52 that can press the recording medium F between the heating roller 51, and a surface of the heating roller 51. And a temperature sensor 55 arranged in the vicinity.

The heating roller 51 has a heating element 53 such as a halogen lamp heater, which is a heat source, built-in along the axial direction in a hollow roller, and the controller 20 (based on the temperature detected by the temperature sensor 55). By controlling the amount of heat generated by the heating element 53 in FIG. 4), the temperature of the heating roller 51 can be adjusted to be maintained within a predetermined temperature range, and the heating temperature of the recording medium F can be adjusted appropriately.

Further, the heating roller 51 has a gear (not shown) provided at the end thereof in the fixing portion drive mechanism 26 (FIG. 4).
The driving force of the drive motor is transmitted by meshing with the gear of the drive motor included in, and is rotationally driven in the rotation direction R.
Further, the heating roller 51 is preferably formed of a material having high thermal conductivity, whereby the recording medium F can be efficiently heated by the heat from the heating element 53, and for example, a metal roller is preferable. It is preferable that the surface of the heating roller 51 has a fluororesin layer, which can prevent ink contamination when the recording medium F is heated and pressed.

The pressure roller 52 is composed of a metal roller such as stainless steel having a rubber coating layer 52c having elasticity on the outer circumference, and roller shafts 52b at both ends thereof are rotatably attached to the support member 58 via bearings 52a. Supported. The supporting member 58 is urged by the pressing members 52 and 57 such as coil springs so that the pressing roller 52 presses the recording medium F against the heating roller 51 with a predetermined pressing force to form the nip 59. It is biased upward with a substantially constant biasing force. The pressure sensor 27 is arranged so as to come into contact with the upper surface of the support member 58 in the figure, and the pressure sensor 27 measures the pressure applied to the recording medium F between the heating roller 51 and the pressure bonding roller 52.

The longitudinal elastic modulus (Young's modulus) of the rubber coating layer 52c of the pressure roller 52 is preferably in the range of 10 ⁶ to 10 ⁷ Pa, more preferably 1.0 × 10 ^{6 to} 4.0 × 10 ⁶ Pa. . Thereby, the heating roller 51 and the pressure roller 5
The pressure applied to the recording medium F between the recording medium F and the recording medium F is controlled within a predetermined range as described below, so that the width of the nip portion 59 causes the heating roller 51 and the pressure roller 52 to make a large contact with the recording medium F. The size can be set to an appropriate size that allows pressure contact in the area, and the pressing force and the pressing time can be obtained with a simple configuration.

The rubber coating layer 52c of the pressure roller 52
Instead, the outer circumference of the heating roller 51 may be covered with heat-resistant silicone rubber or the like so as to have a longitudinal elastic modulus within the above range.
Both of the two may have a longitudinal elastic modulus in the above range.

Further, the fixing member drive mechanism 2 is configured so that the support member 58 of the pressure roller 52 presses the heating roller 51 in the direction A shown in FIG. 3 and releases the pressure in the direction A'opposite thereto.
6 (FIG. 4). The pressing force of the pressure roller 52 in the direction of arrow A is applied to the urging member 5.
The pressure applied to the recording medium F between the heating roller 51 and the pressure bonding roller 52 is obtained by applying a substantially constant urging force of the pressure sensors 6 and 57. However, the control unit 20 calculates the pressure based on the measurement result of the pressure sensor 27. The pressure applied to the recording medium F can be adjusted by controlling the pressure applied to the pressure roller 52 in the directions of arrows A and A ′ via the fixing unit drive mechanism 26. In this case, the pressure applied to the recording medium F is 9.8 × 10 ^{4 to} 4.9 × 1.
The range of 0 ⁶ Pa is preferable. As a result, it is possible to obtain a pressing force necessary and sufficient to make the ink receiving layer of the recording medium F, which will be described later, excellently transparent.

The controller 20 controls the number of rotations of the heating roller 51 and the pair of conveyance rollers 16a and 16b.
By controlling the moving speed of the recording medium F in the transport direction S, the heating and pressurizing time of the recording medium F in the fixing unit 50 can be appropriately adjusted.

Next, the control system of the ink jet printer of FIG. 1 will be described with reference to FIG. FIG. 4 is a block diagram showing a control system of the inkjet printer of FIG.
As shown in FIG. 4, the inkjet printer of FIG.
As its control system, a control unit 2 for controlling the entire device
0, an image memory 21 that stores image data signals input from an external device such as a personal computer, an operation panel 22 that allows the user to input various control information, and a drive signal to the line head 11. And a cut portion drive mechanism 25 for driving the cut portion 40, and a fixing portion drive mechanism 26 for driving the fixing portion 50.

The controller 20 controls the nozzle row 6a of the serial head 6 based on the image data signal from the image memory 21.
The head drive circuit 23 is caused to generate a drive signal for driving the serial head 11 so that ink is ejected from each of the nozzles 6c to 6c, and the application timing of the drive signal from the head drive circuit 23 to each nozzle is controlled.

The control unit 20 also controls the cutting unit drive mechanism 2 based on the position information of the recording medium F from the detection sensor 41.
5, the movement of the cutting member 42 is controlled, and the temperature sensor 55
The temperature of the heating roller 51 is controlled by adjusting the amount of heat generated by the heating element 53 on the basis of the temperature information from the temperature information, and the rotation of the heating roller 51, etc. by the fixing unit drive mechanism 26 and the movement in the directions A and A '. By controlling, the heating temperature, the pressure, and the heating / pressurizing time to the recording medium F can be adjusted.

Next, the recording medium F will be described. Figure 5
FIG. 3 is a sectional view schematically showing a sectional configuration of a recording medium F.
As shown in FIG. 5, the recording medium F includes a support 71 and a surface layer 73 containing thermoplastic resin particles (latex particles).
And a surface layer 73 having a void layer in which the ink solvent component is absorbed after the coloring material and the ink solvent component are separated on the surface of the surface layer 73.
And an ink absorption layer 72 formed between the support 71 and
And used as an inkjet recording sheet.

In addition, the ink absorption capacity of the recording medium F
Is 22-60 ml / m^TwoAnd preferably 25 to 6
0 ml / m^TwoAnd more preferably 25-35 ml
/ M ^TwoIs.

Here, the above-mentioned ink absorption capacity can be obtained as follows. That is, a recording medium having a constant area is conditioned under an atmosphere of 25 ° C. and 50% RH for 24 hours or more, and then the recording medium is immersed in pure water for 10 seconds. At this time, as the water is absorbed, the air in the voids of the recording medium adheres to the surface as bubbles to prevent water absorption. Therefore, the recording medium is appropriately vibrated to remove the bubbles. After 10 seconds, the recording medium is pulled out of water, the water content on the surface is quickly removed with a water absorbing material such as filter paper, and then the ink absorption amount can be determined from the change in mass before and after the immersion.

Next, the ink absorbing layer 72 of the recording medium F will be described. Generally, the ink absorbing layer is roughly classified into a swelling type and a void type. As the swelling type, a water-soluble binder is used, and for example, gelatin, polyvinyl alcohol, polyvinylpyrrolidone, polyethylene oxide or the like is applied alone or in combination, and this is used as an ink absorbing layer.

As the void type, fine particles and a water-soluble binder are mixed and applied, and those having a gloss are particularly preferable. As fine particles, alumina or silica is preferable, and silica having a particle diameter of 0.1 μm or less is particularly preferable. As the water-soluble binder, gelatin, polyvinyl alcohol, polyvinylpyrrolidone, polyethylene oxide and the like are preferably used alone or in combination.

Of the two types described above, a faster ink absorption speed on the recording medium is more suitable for continuous high-speed printing. From this point, the void type is particularly preferably used in the present embodiment. You can

The void type ink absorbing layer will be described in more detail below. The void layer is mainly formed by soft aggregation of the hydrophilic binder and the inorganic fine particles. Conventionally, various methods for forming voids in a film are known,
For example, a method in which a uniform coating solution containing two or more kinds of polymers is applied on a support, and these polymers are phase-separated from each other in a drying process to form voids, solid fine particles and a hydrophilic or hydrophobic resin are used. After coating the coating liquid containing it on a support and drying it, the ink jet recording paper is immersed in water or a liquid containing an appropriate organic solvent to dissolve solid fine particles to form voids, and foaming is performed during film formation. After applying a coating solution containing a compound having properties, a method of foaming this compound in the drying process to form voids in the film, and a coating solution containing porous solid fine particles and a hydrophilic binder is applied on a support. Then, a method of forming voids in the porous fine particles or between the fine particles, and containing solid fine particles and / or fine particle oil droplets and a hydrophilic binder having a volume substantially equal to or more than that of the hydrophilic binder. Coating a coating solution on a support, and a method of forming an air gap between the solid particles are known. In the present embodiment, it is particularly preferable that the void layer is formed by containing various inorganic solid fine particles having an average particle diameter of 100 nm or less.

Examples of the inorganic fine particles used for the above purpose include light calcium carbonate, heavy calcium carbonate, magnesium carbonate, kaolin, clay, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc hydroxide. , Zinc sulfide, zinc carbonate, hydrotalcite, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, synthetic amorphous silica, colloidal silica, alumina, colloidal alumina, pseudo-boehmite, aluminum hydroxide, lithopone, zeolite, hydroxylation Examples thereof include white inorganic pigments such as magnesium.

The average particle size of the inorganic fine particles is a simple average value obtained by observing the particles themselves or particles appearing on the cross section or surface of the void layer with an electron microscope and measuring the particle size of 1,000 arbitrary particles. It is calculated as (number average). Here, the particle size of each particle is represented by the diameter assuming a circle equal to the projected area.

As the inorganic fine particles, solid fine particles selected from silica and alumina or alumina hydrate are preferably used.

As silica which can be used in the present embodiment, silica synthesized by an ordinary wet method, colloidal silica, silica synthesized by a vapor phase method, or the like is preferably used, and particularly in the present embodiment. As the fine particle silica used preferably, colloidal silica or fine particle silica synthesized by a vapor phase method is preferable, and among them, fine particle silica synthesized by a vapor phase method not only obtains a high porosity but also fixes a dye. Coarse aggregates are less likely to be formed when added to the cationic polymer used for the purpose, which is preferable. Further, the alumina or the alumina hydrate may be crystalline or amorphous,
In addition, irregular-shaped particles, spherical particles, needle-shaped particles, or any other shape can be used.

The inorganic fine particles are preferably in a state in which the fine particle dispersion liquid before mixing with the cationic polymer is dispersed up to the primary particles.

The particle size of the inorganic fine particles is preferably 100 nm or less. For example, in the case of the gas phase method fine particle silica, the average particle diameter of the primary particles of the inorganic fine particles dispersed in the state of primary particles (particle diameter in the dispersion state before coating) is
It is preferably 100 nm or less, more preferably 4 to
50 nm, most preferably 4 to 20 nm.

As the most preferably used silica synthesized by a vapor phase method having an average primary particle diameter of 4 to 20 nm, for example, Aerosil manufactured by Nippon Aerosil Co., Ltd. is commercially available. The fine particles of the vapor phase method silica can be relatively easily dispersed even in water by suction with a jet stream inductor mixer manufactured by Mitamura Riken Kogyo Co., Ltd.

The ink absorbing layer preferably contains a water-soluble binder. Examples of the water-soluble binder include polyvinyl alcohol, gelatin, polyethylene oxide, polyvinylpyrrolidone, polyacrylic acid, polyacrylamide, polyurethane, Dextran, dextrin, color genin (κ, ι, λ, etc.),
Examples include agar, pullulan, water-soluble polyvinyl butyral, hydroxyethyl cellulose, carboxymethyl cellulose and the like. It is also possible to use two or more of these water-soluble binders in combination.

The water-soluble binder preferably used in this embodiment is polyvinyl alcohol. The polyvinyl alcohol includes not only ordinary polyvinyl alcohol obtained by hydrolyzing polyvinyl acetate, but also modified polyvinyl alcohol such as cation-modified polyvinyl alcohol at the terminal and anion-modified polyvinyl alcohol having an anionic group.

As the polyvinyl alcohol obtained by hydrolyzing vinyl acetate, those having an average degree of polymerization of 1,000 or more are preferably used, and particularly, the average degree of polymerization is from 1,500 to 1,500.
Those of 5,000 are preferably used. Further, the saponification degree is preferably 70 to 100%, and 80 to 99.
5% is particularly preferable.

As the cation-modified polyvinyl alcohol, for example, a primary to tertiary amino group or a quaternary ammonium group as described in JP-A-61-10483 can be used as the main chain or side chain of the polyvinyl alcohol. The polyvinyl alcohol contained therein is obtained by saponifying a copolymer of an ethylenically unsaturated monomer having a cationic group and vinyl acetate.

Examples of the ethylenically unsaturated monomer having a cationic group include trimethyl- (2-acrylamido-2,2-dimethylethyl) ammonium chloride and trimethyl- (3-acrylamido-3,3-dimethylpropyl). ) Ammonium chloride, N-vinylimidazole, N-vinyl-2-methylimidazole, N
-(3-dimethylaminopropyl) methacrylamide,
Hydroxylethyltrimethylammonium chloride, trimethyl- (2-methacrylamidopropyl) ammonium chloride, N- (1,1-dimethyl-3-)
Examples include dimethylaminopropyl) acrylamide.

The ratio of the cation-modified group-containing monomer of the cation-modified polyvinyl alcohol is 0.1 to 10 mol%, preferably 0.2 to 5 mol% with respect to vinyl acetate.

The anion-modified polyvinyl alcohol is described in, for example, polyvinyl alcohol having an anionic group as described in JP-A-1-206088 and JP-A-61-237681 and 63-307979. Such a copolymer of vinyl alcohol and a vinyl compound having a water-soluble group, and JP-A-7-285.
The modified polyvinyl alcohol which has a water-soluble group as described in No. 265 is mentioned.

As the nonion-modified polyvinyl alcohol, for example, a polyvinyl alcohol derivative obtained by adding a polyalkylene oxide group to a part of vinyl alcohol as described in JP-A-7-9758, JP-A-8-25795. And a block copolymer of a vinyl compound having a hydrophobic group and vinyl alcohol as described in 1. Polyvinyl alcohol can be used in combination of two or more kinds such as different degree of polymerization and modification.

The amount of the inorganic fine particles used in the ink absorbing layer depends on the required ink absorbing capacity, the porosity of the void layer,
Generally depends on the type of inorganic pigment and the type of water-soluble binder, but generally 5 to 30 per 1 m ^{2 of} recording paper.
g, preferably 10 to 25 g.

The ratio of the inorganic fine particles used in the ink absorbing layer to the water-soluble binder is usually 2: 1 to 2 by mass.
It is preferably 0: 1, and particularly preferably 3: 1 to 10: 1.

Further, a cationic water-soluble polymer having a quaternary ammonium salt group in its molecule may be contained, and usually 0.1 to 10 per 1 m ^{2 of} ink jet recording paper.
g, preferably in the range of 0.2-5 g.

In the void layer, the total amount of voids (void volume)
Is preferably 20 ml or more per 1 m ² of recording paper. When the void volume is less than 20 ml / m ^{2 and} the ink amount during printing is small, the ink absorbability is good, but when the ink amount is large, the ink is not completely absorbed and the image quality is degraded. Problems such as delayed drying tend to occur.

In the void layer having an ink holding ability, the void volume with respect to the solid content volume is called the void ratio. In the present embodiment, it is preferable that the porosity is 50% or more because the voids can be efficiently formed without unnecessarily increasing the film thickness.

As another type of void type, a polyurethane resin emulsion, a water-soluble epoxy compound and /
Or in combination with acetoacetylated polyvinyl alcohol,
Further, the ink absorbing layer may be formed by using a coating liquid in which epichlorohydrin polyamide resin is used in combination. The polyurethane resin emulsion in this case is preferably a polyurethane resin emulsion having a polycarbonate chain, a polycarbonate chain and a polyester chain and having a particle diameter of 3.0 μm, and the polyurethane resin of the polyurethane resin emulsion is a polycarbonate polyol, a polyol having a polycarbonate polyol and a polyester polyol. Polyurethane resin obtained by reacting with an aliphatic isocyanate compound has a sulfonic acid group in the molecule, and further has an epichlorohydrin polyamide resin and a water-soluble epoxy compound and / or acetoacetylated vinyl alcohol. preferable. It is presumed that in the ink absorbing layer using the polyurethane resin, weak cations and anions are formed, and along with this, voids having an ink dissolving and absorbing ability are formed, so that an image can be formed.

In the present embodiment, it is preferable to use a curing agent. The curing agent can be added at any time during the production of the ink jet recording medium, and for example, it may be added to the coating liquid for forming the ink absorbing layer, but after the ink absorbing layer is formed, the above water-soluble binder is cured. It is preferable to supply the agent.

In the present embodiment, the method of supplying the curing agent for the water-soluble binder after the formation of the ink absorption layer may be used alone, but preferably the above-mentioned curing agent is applied for forming the ink absorption layer. It is to be used in combination with the method of adding to the liquid.

The curing agent that can be used in the present embodiment is not particularly limited as long as it causes a curing reaction with a water-soluble binder, but boric acid and salts thereof are preferred, but other known agents are also available. Can be used, generally is a compound having a group capable of reacting with the water-soluble binder or a compound that promotes the reaction between different groups of the water-soluble binder, and is appropriately selected according to the type of the water-soluble binder. Used. Specific examples of the curing agent include, for example,
Epoxy curing agent (diglycidyl ethyl ether, ethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-diglycidyl cyclohexane, N, N-diglycidyl-4-glycidyloxyaniline, sorbitol polyglycidyl ether , Glycerol polyglycidyl ether, etc.), aldehyde curing agents (formaldehyde, glyoxal, etc.), active halogen curing agents (2,4-dichloro-4-)
Hydroxy-1,3,5, -s-triazine etc.), active vinyl compounds (1,3,5-trisacryloyl-hexahydro-s-triazine, bisvinylsulfonylmethyl ether etc.), aluminum alum and the like.

Boric acid or a salt thereof means an oxyacid having a boron atom as a central atom and a salt thereof, and specifically, orthoboric acid, diboric acid, metaboric acid, tetraboric acid,
Pentaboric acid and octaboric acid and their salts are mentioned.

The boric acid having a boron atom and its salt as a curing agent may be used in the form of a single aqueous solution or in a mixture of two or more kinds. Particularly preferred is a mixed aqueous solution of boric acid and borax.

The aqueous solutions of boric acid and borax can be added only in relatively dilute aqueous solutions, but by mixing them, a concentrated aqueous solution can be obtained and the coating solution can be concentrated. . Further, there is an advantage that the pH of the aqueous solution to be added can be controlled relatively freely.

The total amount of the curing agent used is preferably 1 to 600 mg per 1 g of the water-soluble binder. In addition, the supply amount is 100 to 6 per 1 g of the water-soluble binder.
00 mg is preferred.

The surface layer 73 of the recording medium F according to the present embodiment contains a thermoplastic resin, and preferably contains an inorganic pigment together with the thermoplastic resin.

The surface layer in the present embodiment is not limited to the outermost surface layer and is not particularly limited as long as the effect of the present embodiment is exhibited. The recording medium of the present embodiment, after image recording, for example, by melting the thermoplastic resin contained in the surface layer by heating, to form a film,
Many of the effects of this embodiment are exhibited. For example, if a pigment ink is printed and image quality is improved with or without heat treatment after image recording, for example, glossiness is improved, abrasion resistance is improved, or the degree of bronzing is improved, a thermoplastic resin, or Even if the layer containing the inorganic pigment and the thermoplastic resin is not the outermost layer, the structure thereof corresponds to this embodiment.

Preferred constitutional examples for clearly indicating the surface layer in the present embodiment are listed below, but the layer constitution of the recording medium according to the present invention is not limited to these. 1: A structure in which a void-type ink absorbing layer 72 is provided on a support 71, and a layer 73 containing a thermoplastic resin or an inorganic pigment and a thermoplastic resin thereon is the outermost layer. 2: A layer-type ink absorbing layer 72 was formed on a support 71, and a thermoplastic resin, or an inorganic pigment and a thermoplastic resin was contained on the layer 73, for the purpose of improving surface properties. Structure with a thin layer. 3: A layer-type ink absorption layer 72 is provided on a support 71, and a thermoplastic resin, or an inorganic pigment and a thermoplastic resin is included on the layer 73, for the purpose of cutting harmful light. A structure provided with a thin layer having an ultraviolet absorbing function. 4: A layer containing a matting agent was provided on a layer 73 having a void-type ink absorbing layer 72 on a support 71, on which a thermoplastic resin or an inorganic pigment and a thermoplastic resin was contained. Constitution. 5: A structure in which a void-type ink absorbing layer 72 is provided on a support 71, and a peelable layer is provided on a layer 73 containing a thermoplastic resin or an inorganic pigment and a thermoplastic resin on the void type ink absorbing layer 72. .

The most preferable constitution among the constitution examples described above is the case where the layer containing the inorganic pigment and the thermoplastic resin is the outermost layer. The surface layer containing the thermoplastic resin or the inorganic pigment and the thermoplastic resin may contain the inorganic pigment, the thermoplastic resin and, if necessary, the binder component.

The above-mentioned inorganic pigment can be selected from the inorganic fine particles that can be used in the above-mentioned void layer. For example, light calcium carbonate, heavy calcium carbonate, magnesium carbonate, kaolin, clay, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc hydroxide, zinc sulfide, zinc carbonate, hydrotalcite, aluminum silicate, diatomaceous Examples thereof include earth, calcium silicate, magnesium silicate, synthetic amorphous silica, colloidal silica, alumina, colloidal alumina, pseudo-boehmite, aluminum hydroxide, lithopone, zeolite, and white inorganic pigments such as magnesium hydroxide.

As the preferred inorganic pigment, solid fine particles selected from silica and alumina or alumina hydrate are preferably used, and silica is more preferred.

As the silica, silica synthesized by a usual wet method, colloidal silica, silica synthesized by a vapor phase method or the like is preferably used, and particularly preferably used fine particle silica is colloidal silica or a vapor phase method. The fine particle silica synthesized in 1. is preferable. Among them, the fine particle silica synthesized by the gas phase method not only provides a high porosity, but also a coarse aggregate when added to the cationic polymer used for the purpose of immobilizing the dye. Are less likely to be formed, which is preferable. Further, the alumina or alumina hydrate may be crystalline or amorphous, and those having any shape such as amorphous particles, spherical particles and acicular particles can be used.

The inorganic pigment is preferably in a state in which the fine particle dispersion liquid before mixing with the cationic polymer is dispersed up to the primary particles. The particle size of the inorganic pigment is 100n.
It is preferably m or less. For example, in the case of gas phase method fine particle silica, the average particle diameter of the primary particles of the inorganic pigment dispersed in the state of primary particles (particle diameter in the dispersion liquid state before coating) is
It is preferably 100 nm or less, more preferably 4 to
50 nm, most preferably 4 to 20 nm.

Examples of the thermoplastic resin which can be used in the present embodiment include polycarbonate, polyacrylonitrile, polystyrene, polyacrylic acid, polymethacrylic acid, polyvinyl chloride, polyvinylidene chloride,
Examples thereof include polyvinyl acetate, polyester, polyamide, polyether, copolymers thereof and salts thereof.
Among them, styrene-acrylic acid ester copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-acrylic acid ester copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylic acid ester copolymer, SBR latex preferable. In addition, the thermoplastic resin may be used by mixing a plurality of polymers having different monomer compositions, particle sizes, and degrees of polymerization.

In selecting the thermoplastic resin, consideration should be given to the ink receiving property of the recording medium, the glossiness of the image after fixing by heating and pressing, the image fastness and the releasability.

Regarding the ink receptivity, when the particle diameter of the thermoplastic resin is less than 0.05 μm, the separation of the pigment particles and the ink solvent in the pigment ink becomes slow and the ink absorption speed is lowered. On the other hand, if it exceeds 10 μm, it is not preferable from the viewpoint of film strength and gloss deterioration of the inkjet recording medium after coating and drying. For this reason, the preferable thermoplastic resin diameter is preferably 0.05 to 10 μm,
More preferably, it is 0.1 to 5 μm. More preferably, it is 0.1 to 1 μm.

The glass transition point (Tg) is a criterion for selecting the thermoplastic resin. When Tg is lower than the coating drying temperature, for example, the coating drying temperature at the time of manufacturing the recording medium is already higher than Tg, the ink solvent permeates, and the voids due to the thermoplastic resin disappear. See also T
If g is higher than the temperature at which the support is denatured by heat, a fixing operation at a high temperature is required in order to melt and form a film after ink jet recording with a pigment ink. Thermal stability etc. becomes a problem. The preferable Tg of the thermoplastic resin is 50 to 150 ° C. Also,
The minimum film forming temperature (MFT) is preferably 50 to 150 ° C.

From the viewpoint of environmental suitability, the thermoplastic resin is preferably dispersed in an aqueous system, and particularly preferably an aqueous latex obtained by emulsion polymerization. At this time, the type of emulsion polymerization using a nonionic dispersant as an emulsifier is
This is a form that can be preferably used. From the viewpoint of odor and safety, the thermoplastic resin used preferably has a small amount of residual monomer components, and is preferably 3% by mass or less, more preferably 1% by mass or less, based on the solid content of the polymer. It is preferably 0.1% by mass or less.

In the case of the surface layer containing an inorganic pigment and a thermoplastic resin, the solid content mass ratio of thermoplastic resin / inorganic pigment can be selected from the range of 90/10 to 10/90, preferably 70/30 to 30 /. The range is 70, more preferably 60/40 to 40/60.

The solid content of the thermoplastic resin contained in the surface layer 73 is 2 g / m ² or more and 20 g / m ² or less, preferably ^{2 to} 15 g / m ^2, more preferably ² g / m 2. It is in the range of 0.5 to 10 g / m ² . If the solid content of the thermoplastic resin is too small, a sufficient film cannot be formed and the pigment cannot be sufficiently dispersed in the film. Therefore, the image quality and gloss are not sufficiently improved. Also,
When the solid content of the thermoplastic resin is too large, the thermoplastic resin cannot be completely formed into a film in a short heating step, and the fine particles remain as opaqueness, which deteriorates the image quality. In addition, the ink absorption speed is also reduced, causing bleeding at the boundary, which is a problem.

The surface layer coating liquid containing the inorganic pigment and the thermoplastic resin may be prepared by simultaneously dispersing the inorganic pigment and the thermoplastic resin, or may be prepared by dispersing them and mixing them at the time of preparing the coating liquid.

The support 71 of the recording medium F is a support conventionally used for ink jet recording media, for example, a paper support such as plain paper, art paper, coated paper and cast coated paper, a plastic support, A paper support having both surfaces coated with a polyolefin, a composite support obtained by laminating these together, and the like can be appropriately selected and used.

Further, in the recording medium F, for the purpose of increasing the adhesive strength between the support 71 and the ink absorbing layer 72, prior to coating the ink absorbing layer 72, the support is subjected to corona discharge treatment or undercoating treatment. Is preferably performed. Furthermore, the recording medium F does not necessarily have to be colorless and may be colored recording paper.

In the recording medium F, a paper support having both sides of a base paper support laminated with polyethylene or the like is used.
It is particularly preferable because the recorded image is close to photographic quality and a high quality image can be obtained at low cost. A paper support laminated with such polyethylene will be described below.

The base paper used for the paper support is mainly made of wood pulp, and if necessary, synthetic paper such as polypropylene or synthetic fiber such as nylon or polyester is used in addition to wood pulp. As wood pulp, LBKP, LBSP, NBKP, NBSP,
Any of LDP, NDP, LUKP, and NUKP can be used, but LBKP, NBSP, which has a large amount of short fibers,
It is preferable to use more LBSP, NDP, and LDP. However, the ratio of LBSP and / or LDP is 1
0 mass% or more and 70 mass% or less are preferable.

As the above pulp, a chemical pulp containing few impurities (sulfate pulp or sulfite pulp) is preferably used, and a pulp whose whiteness is improved by bleaching is also useful. The base paper contains sizing agents such as higher fatty acids and alkyl ketene dimers, white pigments such as calcium carbonate, talc and titanium oxide, paper strength enhancers such as starch, polyacrylamide and polyvinyl alcohol, optical brighteners and polyethylene glycols. A water retention agent such as, a dispersant, and a softening agent such as quaternary ammonium can be appropriately added.

The freeness of pulp used for papermaking is CSF.
Is preferably 200 to 500 ml, and the fiber length after beating is 30 to 70% of the sum of the mass% of the 24 mesh residue and the mass% of the 42 mesh residue defined in JIS-P-8207. preferable. The mass% of the 4-mesh residue is preferably 20 mass% or less. The basis weight of the base paper is preferably 30 to 250 g / m ² , and particularly 50 to ²
00 g / m ² is preferred. The thickness of the base paper is 40-250μ
m is preferred. The base paper can be given a high smoothness by calendering at the papermaking stage or after the papermaking. Base paper density is 0.7 to 1.2 g / m ² (JIS-P-8118)
Is common. Furthermore, the stiffness of base paper is JIS-P-814.
20 to 200 g is preferable under the conditions specified in 3. A surface sizing agent may be applied to the surface of the base paper, and as the surface sizing agent, the same sizing agent as that which can be added to the base paper can be used. The pH of the base paper is preferably 5 to 9 when measured by the hot water extraction method specified in JIS-P-8113.

The polyethylene for coating the front surface and the back surface of the base paper is mainly low-density polyethylene (LDPE) and / or high-density polyethylene (HDPE), but in addition, LLDPE (linear rhodity polyethylene), polypropylene and the like are partially used. Can be used. In particular, the polyethylene layer on the ink absorption layer side is preferably one in which rutile or anatase type titanium oxide is added to polyethylene to improve opacity and whiteness, as is widely used in photographic printing paper. The titanium oxide content is usually 3 to 20 mass% with respect to polyethylene,
It is preferably 4 to 13% by mass.

The polyethylene-coated paper can be used as a glossy paper, or when a polyethylene is melt-extruded on the surface of a base paper for coating, a so-called patterning treatment is carried out to obtain a matte surface which can be obtained by ordinary photographic printing paper. Those with a silky surface can also be used.

The amount of polyethylene used on the front and back sides of the base paper is selected so as to optimize curling under low and high humidity after providing the void layer and the back layer, but usually the polyethylene layer on the void layer side is used. Is 20 to 40 μm, and the back layer side is 10
It is in the range of 30 μm.

Further, the polyethylene-coated paper support preferably has the following characteristics. 1. Tensile strength: Strength specified by JIS-P-8113, 20 to 300 N in the vertical direction and 10 to 20 in the horizontal direction.
It is preferably 0N. 2. Tear strength: A method defined in JIS-P-8116, 0.1 to 20 N in the longitudinal direction and 2 to 20 N in the lateral direction.
Is preferred. 3. Compression modulus ≧ 98.1 MPa 4. Surface Beck smoothness: 20 seconds or more is preferable as a glossy surface under the conditions specified in JIS-P-8119,
It may be less than this for so-called molded products. 5. Surface roughness: The surface roughness defined by JIS-B-0601 has a maximum height of 10 μ per reference length of 2.5 mm.
It is preferably m or less. 6. Opacity: When measured by the method specified in JIS-P-8138, 80% or more, particularly 85 to 98% is preferable. 7. Whiteness: L *, a defined by JIS-Z-8729
* And b * are L * = 80 to 95, a * = − 3 to +5, b * =
It is preferably -6 to +2. 8. Surface gloss: 6 specified in JIS-Z-8741
The 0 degree specular gloss is preferably 10 to 95%. 9. Clark stiffness: Clark stiffness in the conveying direction S of the recording medium, the support is 50~300cm ^2/100 is preferred. 10. Water content of middle paper: usually 2 to 100% by mass, preferably 2 to 6% by mass based on the middle paper

Next, a method of manufacturing the recording medium F will be described. As a method for producing this recording medium, each of the constituent layers including the ink absorbing layer can be produced individually or simultaneously by appropriately selecting from known coating methods, coating on a support and drying. As the coating method, for example, roll coating method, rod bar coating method, air knife coating method, spray coating method, curtain coating method, or U.S. Pat.
A slide bead coating method using a hopper described in JP-A-2,761,791 and an extrusion coating method are preferably used.

When the slide bead coating method is used, the viscosity of each coating solution for simultaneous multi-layer coating is 5
The range is preferably from 100 to 100 mPa · s, more preferably from 10 to 50 mPa · s. When using the curtain coating method, the range of 5 to 1200 mPa · s is preferable, and the range of 25 to 500 mPa is more preferable.
・ S range.

Further, the viscosity of the coating liquid at 15 ° C. is preferably 100 mPa · s or more, 100 to 30,
000 mPa · s is more preferable, still more preferably 3,000 to 30,000 mPa · s, and most preferably 10,000 to 30,000 mPa · s.

As a coating and drying method, the coating liquid is 3 times.
It is preferable that after the simultaneous multilayer coating is performed by heating to 0 ° C. or higher, the temperature of the formed coating film is once cooled to 1 to 15 ° C. and dried at 10 ° C. or higher. During preparation of the coating solution, during coating and during drying, it is preferable to prepare, coat and dry the coating solution at a temperature not higher than Tg of the thermoplastic resin so that the thermoplastic resin contained in the surface layer does not form a film. More preferably,
As the drying conditions, a wet bulb temperature of 5 to 50 ° C. and a film surface temperature of 10
It is carried out under the condition of a temperature range of 50 ° C. In addition, as a cooling method immediately after coating, it is preferable to use a horizontal setting method from the viewpoint of uniformity of the formed coating film.

In addition, it is preferable that the manufacturing process of the recording medium has a step of supplying a curing agent for the water-soluble binder after the ink absorbing layer is formed. The method of supplying the curing agent is not particularly limited, and for example, a method of applying a solution containing the curing agent after forming the ink absorbing layer, a method of spraying the solution containing the curing agent onto the surface of the recording medium on which the ink absorbing layer has been formed. Etc. can be appropriately selected and used.

In the manufacturing process, the temperature is 35 ° C. or higher and 70 ° C.
It is preferable to have a step of storing for 24 hours or more and 60 days or less under the following conditions. This heating condition is 35 ° C or higher,
There is no particular limitation as long as it is stored at 70 ° C. or lower for 24 hours or longer and 60 days or shorter, but preferable examples include:
For example, 36 ° C. for 3 days to 4 weeks, 40 ° C. for 2 days to 2 weeks, or 55 ° C. for 1 to 7 days. By performing this heat treatment, it is possible to accelerate the curing reaction of the water-soluble binder or accelerate the crystallization of the water-soluble binder,
As a result, preferable ink absorbency can be achieved.

Any of dye inks, pigment inks, water-based inks, oil-based inks, and hot-melt inks can be used for the above-mentioned recording medium F. In particular, water-based dye inks,
Water-based pigment inks and oil-based pigment inks are suitable, and water-based dye inks and water-based pigment inks are more suitable. Thus, an aqueous ink composition (for example, an aqueous inkjet recording liquid containing 10% by mass or more of water based on the total mass of the ink) is preferable.

Next, the above-mentioned pigment ink will be described. The pigment ink is preferable from the viewpoint of image storability. As the pigment used in the pigment ink, an insoluble pigment, an organic pigment such as a lake pigment, and carbon black can be preferably used.

The insoluble pigment is not particularly limited, but for example, azo, azomethine, methine, diphenylmethane, triphenylmethane, quinacridone, anthraquinone, perylene, indigo, quinophthalone, isoindolinone, isoindoline, azine, oxazine. ,
Thiazine, dioxazine, thiazole, phthalocyanine, diketopyrrolopyrrole and the like are preferable.

Specific pigments that can be preferably used include the following pigments. Examples of magenta or red pigments include C.I. I. Pigment Red 2, C.I. I. Pigment Red 3, C.I. I. Pigment Red 5, C.I. I. Pigment Red 6, C.I.
I. Pigment Red 7, C.I. I. Pigment Red 1
5, C.I. I. Pigment Red 16, C.I. I. Pigment Red 48: 1, C.I. I. Pigment Red 53:
1, C.I. I. Pigment Red 57: 1, C.I. I. Pigment Red 122, C.I. I. Pigment Red 12
3, C.I. I. Pigment Red 139, C.I. I. Pigment Red 144, C.I. I. Pigment Red 149,
C. I. Pigment Red 166, C.I. I. Pigment Red 177, C.I. I. Pigment Red 178, C.I.
I. Pigment Red 222 and the like.

Examples of pigments for orange or yellow include C.I. I. Pigment Orange 31, C.I.
I. Pigment Orange 43, C.I. I. Pigment Yellow 12, C.I. I. Pigment Yellow 13, C.I. I.
Pigment Yellow 14, C.I. I. Pigment Yellow 15, C.I. I. Pigment Yellow 17, C.I. I. Pigment Yellow 93, C.I. I. Pigment Yellow 9
4, C.I. I. Pigment Yellow 138 and the like.

As the pigment for green or cyan,
For example, C.I. I. Pigment Blue 15, C.I. I. Pigment Blue 15: 2, C.I. I. Pigment Blue 1
5: 3, C.I. I. Pigment Blue 16, C.I. I. Pigment Blue 60, C.I. I. Pigment Green 7 and the like.

A pigment dispersant may be used for these pigments if necessary, and examples of the pigment dispersant which can be used include higher fatty acid salts, alkyl sulfates, alkyl ester sulfates, alkyl sulfonic acids. Salt, sulfosuccinate, naphthalene sulfonate, alkyl phosphate,
Activator such as polyoxyalkylene alkyl ether phosphate, polyoxyalkylene alkyl phenyl ether, polyoxyethylene polyoxypropylene glycol, glycerin ester, sorbitan ester, polyoxyethylene fatty acid amide, amine oxide, or styrene, styrene derivative, vinyl Block copolymers of two or more monomers selected from naphthalene derivatives, acrylic acid, acrylic acid derivatives, maleic acid, maleic acid derivatives, itaconic acid, itaconic acid derivatives, fumaric acid, fumaric acid derivatives, random copolymers Mention may be made of polymers and their salts.

As a method for dispersing the pigment, for example, various dispersing machines such as a ball mill, a sand mill, an attritor, a roll mill, an agitator, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, a pearl mill, a wet jet mill and a paint shaker can be used. it can. Also,
It is also preferable to use a centrifugal separator and a filter for the purpose of removing coarse particles of the pigment dispersion.

The average particle size of the pigment particles in the pigment ink is selected in consideration of stability in the ink, image density, gloss feeling, light resistance, etc. In addition, from the viewpoint of improving gloss and texture. Also, it is preferable to appropriately select the particle size. The reason why the glossiness or texture is improved is not clear at this stage, but in the formed image, the pigment is related to the state in which the pigment is preferably dispersed in the film in which the thermoplastic resin is melted. It is speculated that For high-speed processing, the thermoplastic resin must be melted in a short time to form a film, and the pigment must be sufficiently dispersed in the film. At this time, it is considered that the surface area of the pigment has a great influence, and therefore the average particle size has an optimum region.

The water-based ink composition, which is a preferred form of the pigment ink, is preferably used in combination with a water-soluble organic solvent. Examples of water-soluble organic solvents that can be used include alcohols (eg, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, secondary butanol, tertiary butanol, pentanol, hexanol, cyclohexanol, benzyl alcohol, etc.). , Polyhydric alcohols (for example, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol,
Polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, thiodiglycol), polyhydric alcohol ethers (eg ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether) , Diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, ethylene Recall monophenyl ether, propylene glycol monophenyl ether), amines (e.g., ethanolamine, diethanolamine,
Triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-
Ethylmorpholine, ethylenediamine, diethylenediamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine, pentamethyldiethylenetriamine, tetramethylpropylenediamine, etc., amides (eg, formamide, N, N-dimethylformamide, N, N-dimethyl) Acetamide, etc., heterocycles (for example, 2-pyrrolidone, N-methyl-2-pyrrolidone, cyclohexylpyrrolidone, 2-oxazolidone,
1,3-dimethyl-2-imidazolidinone etc.), sulfoxides (eg dimethyl sulfoxide etc.), sulfones (eg sulfolane etc.), urea, acetonitrile, acetone and the like. Examples of preferable water-soluble organic solvent include polyhydric alcohols. Furthermore, it is particularly preferable to use a polyhydric alcohol and a polyhydric alcohol ether together.

The water-soluble organic solvent may be used alone or in combination of two or more. The total amount of the water-soluble organic solvent added to the ink is 5 to 60% by mass, preferably 10 to
It is 35 mass%.

The ink composition may contain various known additives, if necessary, depending on the purpose of improving ejection stability, compatibility with print heads and ink cartridges, storage stability, image storability, and other properties. For example, a viscosity modifier, a surface tension modifier, a specific resistance modifier, a film-forming agent, a dispersant, a surfactant, a UV absorber, an antioxidant, an anti-fading agent, an anti-fouling agent, an anticorrosive agent, etc. are appropriately selected. For example, polystyrene, polyacrylic acid esters, polymethacrylic acid esters, polyacrylamides, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, or copolymers thereof, urea resins, or Organic latex fine particles such as melamine resin, liquid paraffin, dioctyl phthalate, tricresyl phosphate, silicone oil, etc. Droplet particles, various surfactants of cationic or nonionic, JP 57-74193,
UV absorbers described in JP-A-57-87988 and JP-A-62-261476, JP-A-57-74192 and 57.
-87989, 60-72785, 61-14.
6591, JP-A-1-95091 and 3-133.
No. 76, etc., anti-fading agent, JP-A-59-4
2993, 59-52689, 62-2800.
69, 61-242871, and JP-A-4-21.
Examples thereof include fluorescent whitening agents, pH adjusting agents such as sulfuric acid, phosphoric acid, citric acid, sodium hydroxide, potassium hydroxide, potassium carbonate and the like described in No. 9266.

The viscosity of the ink composition during flight is preferably 40 mPa · s or less, more preferably 2 to 20 mPa · s. The surface tension of the ink composition during flight is preferably 20 mN / m or more,
More preferably, it is 30 to 45 mN / m.

Next, the dye ink will be described. The dye ink in the present embodiment contains water, a dye, and a high boiling point organic solvent.

High boiling organic solvents that can be used in this dye ink include amides (eg, dimethylformamide, dimethylacetamide, etc.), ketones or keto alcohols (eg, diacetone alcohol, etc.), polyalkylene glycols ( For example, polyethylene glycol, polypropylene glycol, etc.), 2
Alkylene glycols having an alkylene group having 6 carbon atoms (for example, ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene glycol, diethylene glycol, etc.) , Glycerin, lower alkyl ethers of polyhydric alcohols (eg, ethylene glycol methyl ether, diethylene glycol methyl (or ethyl) ether, triethylene glycol monomethyl (or ethyl) ether, etc.) and the like.

Among the above-mentioned high boiling point organic solvents, polyhydric alcohols such as diethylene glycol and lower alkyl ethers of polyhydric alcohols such as triethylene glycol monomethyl (or ethyl) ether are preferable.
In the dye ink, the high boiling point organic solvent is preferably 10 to 70% by weight based on the total weight of the ink.

As the dye, a dye selected from a direct dye, an acid dye, a reactive dye, a basic dye and a disperse dye may be used. These dyes may be used alone or in combination of two or more kinds. Good. These dyes are dissolved or dispersed in a solvent which is appropriately selected and used as desired. Typical coloring materials are listed below, but the coloring materials are not limited to these.

<Direct dye>

CI Direct Yellow 1, 4, 8,
11, 12, 24, 26, 27, 28, 33, 39, 4
4, 50, 58, 85, 86, 100, 110, 14
2, 144, CI Direct Red 1, 2, 4,
9, 11, 13, 17, 20, 23, 24, 28, 3
1, 33, 37, 39, 44, 47, 48, 51, 6
2, 63, 75, 79, 80, 81, 83, 89, 9
0, 94, 95, 99, 220, 224, 227, 24
3, CI Direct Blue 1, 2, 6, 8, 15,
22, 25, 71, 76, 78, 80, 86, 87, 9
0, 98, 106, 108, 120, 123, 163,
165, 192, 193, 194, 195, 196, 1
99, 200, 201, 202, 203, 207, 23
6, 237, CI Direct Black 2, 3, 7,
17, 19, 22, 32, 38, 51, 56, 62, 7
1, 74, 75, 77, 105, 108, 112, 11
7,154

<Acid dye>

CI Acid Yellow 2, 3, 7, 1
7, 19, 23, 25, 29, 38, 42, 49, 5
9, 61, 72, 99, CI Acid Orange 5
6, 64, CI Acid Red 1, 8, 14, 1
8, 26, 32, 37, 42, 52, 57, 72, 7
4, 80, 87, 115, 119, 131, 133, 1
34, 143, 154, 186, 249, 254, 25
6, CI Acid Violet 11, 34, 75,
CI Acid Blue 1, 7, 9, 29, 87, 12
6, 138, 171, 175, 183, 234, 23
6,249, CI Acid Green 9,12,1
9, 27, 41, CI Acid Black 1, 2,
7, 24, 26, 48, 52, 58, 60, 94, 10
7, 109, 110, 119, 131, 155

<Reactive Dye>

CI Reactive Yellow 1, 2,
3, 13, 14, 15, 17, 37, 42, 76, 9
5, 168, 175, CI Reactive Red 2,
6, 11, 21, 22, 23, 24, 33, 45, 11
1, 112, 114, 180, 218, 226, 22
8, 235, CI reactive blue 7, 14, 1
5, 18, 19, 21, 25, 38, 49, 72, 7
7, 176, 203, 220, 230, 235, C.I.
Reactive Orange 5, 12, 13, 35, 95,
CI Reactive Brown 7, 11, 33, 37,
46, CI Reactive Green 8, 19, CI
Reactive Violet 2, 4, 6, 8, 21, 2
2, 25, CI Reactive Black 5, 8, 3
1, 39

<Basic dye>

CI Basic Yellow 11, 14,
21, 32, CI Basic Red 1, 2, 9, 1
2, 13, CI Basic Violet 3, 7, 1
4, CI Basic Blue 3, 9, 24, 25

Other dyes that can be used in the dye ink in the present embodiment include chelate dyes and azo dyes used in so-called silver dye bleaching light-sensitive materials (for example, Ciba-Geigy manufactured Cibachrome). it can. Regarding the chelate dye, the description in British Patent 1,077,484 is cited here.

Regarding the azo dyes for the silver dye bleaching photosensitive material, for example, British Patent Nos. 1,039,458, 1,004,957 and 1,077,6 can be used.
No. 28, U.S. Pat. No. 2,612,448 are cited. In the inkjet ink of the present invention, the dye is 1 to 10% by weight based on the total weight of the ink.
It is preferably used.

The disperse dye refers to a dye that is soluble in oil but insoluble or hardly soluble in water and is used for dyeing in a system dispersed in water. The disperse dye is used by dispersing it in a solvent appropriately selected as desired. Examples of typical disperse dyes are shown below, but the invention is not limited thereto.

C. I. Disperse Yellow
3, 4, 5, 7, 9, 13, 24, 30, 33, 34,
42, 44, 49, 50, 51, 54, 56, 58, 6
0, 63, 64, 66, 68, 71, 74, 76, 7
9, 82, 83, 85, 86, 88, 90, 91, 9
3, 98, 99, 100, 104, 114, 116, 1
18, 119, 122, 124, 126, 135, 14
0, 141, 149, 160, 162, 163, 16
4, 165, 179, 180, 182, 183, 18
6, 192, 198, 199, 202, 204, 21
0, 211, 215, 216, 218, 224

C. I. Disperse Orange
1, 3, 5, 7, 11, 13, 17, 20, 21, 2
5, 29, 30, 31, 32, 33, 37, 38, 4
2, 43, 44, 45, 47, 48, 49, 50, 5
3, 54, 55, 56, 57, 58, 59, 61, 6
6, 71, 73, 76, 78, 80, 89, 90, 9
1, 93, 96, 97, 119, 127, 130, 13
9,142

C. I. Disperse Red 1,
4, 5, 7, 11, 12, 13, 15, 17, 27, 4
3, 44, 50, 52, 53, 54, 55, 56, 5
8, 59, 60, 65, 72, 73, 74, 75, 7
6, 78, 81, 82, 86, 88, 90, 91, 9
2, 93, 96, 103, 105, 106, 107, 1
08, 110, 111, 113, 117, 118, 12
1, 122, 126, 127, 128, 131, 13
2, 134, 135, 137, 143, 145, 14
6, 151, 152, 153, 154, 157, 15
9, 164, 167, 169, 177, 179, 18
1, 183, 184, 185, 188, 189, 19
0, 191, 192, 200, 201, 202, 20
3, 205, 206, 207, 210, 221, 22
4, 225, 227, 229, 239, 240, 25
7, 258, 277, 278, 279, 281, 28
8, 298, 302, 303, 310, 311, 31
2,320,324,328

C. I. Disperse Violet
1, 4, 8, 23, 26, 27, 28, 31, 33, 3
5, 36, 38, 40, 43, 46, 48, 50, 5
1, 52, 56, 57, 59, 61, 63, 69, 77

C. I. Disperse Green
9, C.I. I. Disperse Brown 1, 2,
4, 9, 13, 19

C. I. Disperse Blue 3,
7, 9, 14, 16, 19, 20, 26, 27, 35,
43, 44, 54, 55, 56, 58, 60, 62, 6
4, 71, 72, 73, 75, 79, 81, 82, 8
3, 87, 91, 93, 94, 95, 96, 102, 1
06, 108, 112, 113, 115, 118, 12
0, 122, 125, 128, 130, 139, 14
1, 142, 143, 146, 148, 149, 15
3, 154, 158, 165, 167, 171, 17
3, 174, 176, 181, 183, 185, 18
6, 187, 189, 197, 198, 200, 20
1, 205, 207, 211, 214, 224, 22
5, 257, 259, 267, 268, 270, 28
4, 285, 287, 288, 291, 293, 29
5, 297, 301, 315, 330, 333, C.I.
I. Disperse Black 1, 3, 10, 24

The disperse dye is used by mixing it with a dispersant and other additives necessary for desired purposes, and dispersing the mixture with a disperser. As the disperser, a conventionally known ball mill, sand mill, line mill, high pressure homogenizer or the like can be used. A surfactant is used as the dispersant.
These surfactants include cationic, anionic,
Both amphoteric and nonionic can be used.

Examples of the cationic surfactants include aliphatic amine salts, aliphatic quaternary ammonium salts, benzalkonium salts, benzethonium chloride, pyridinium salts and imidazolinium salts.

As the anionic surfactant, fatty acid soap, N-acyl-N-methylglycine salt, N-acyl-
N-methyl-β-alanine salt, N-acylglutamate, acylated peptide, alkyl sulfonate, alkylbenzene sulfonate, alkylnaphthalene sulfonate, dialkylsulfosuccinate ester salt, alkylsulfoacetate salt, α-olefin sulfone Acid salt, N-acylmethyl taurine, sulfated oil, higher alcohol sulfate ester salt, secondary higher alcohol sulfate ester salt, alkyl ether sulfate salt, secondary higher alcohol ethoxy sulfate, polyoxyethylene alkylphenyl ether sulfate salt, Monoglycyl sulphate, fatty acid alkylolamide sulfuric acid ester salt, alkyl ether phosphate ester salt, alkyl phosphate ester salt, lignin sulfonate, formalin condensate of naphthalene sulfonate, alkyl naphthalene sulphate Examples thereof include a formalin condensate of phonate and a formalin condensate of a special aromatic sulfonate [for example, demol C (formalin condensate of creosote oil sulfonate)].

Examples of the amphoteric surfactant include carboxybetaine type, sulfobetaine type, aminocarboxylic acid salts, imidazolinium betaine and the like.

As the nonionic activator, polyoxyethylene secondary alcohol ether, polyoxyethylene alkylphenyl ether, polyoxyethylene sterol ether, polyoxyethylene lanolin derivative polyoxyethylene polyoxypropylene alkyl ether, polyoxyethylene glycerin fatty acid Ester, polyoxyethylene castor oil, hydrogenated castor oil, polyoxyethylene sorbitol fatty acid ester, polyethylene glycol fatty acid ester, fatty acid monoglyceride, polyglycerin fatty acid ester, sorbitan fatty acid ester, propylene glycol fatty acid ester, sucrose fatty acid ester, fatty acid alkanolamide, Polyoxyethylene fatty acid amide, polyoxyethylene alkylamine, alkylamine oxa De, acetylene glycol, acetylene alcohol, block copolymers of ethylene oxide and propylene oxide, and ethylene oxide adduct of alkylphenol.

Preferred surface active agents include lignin sulfonates which are anionic surfactants, formalin condensates of naphthalene sulfonates, formalin condensates of alkylnaphthalene sulfonates, and formalin condensates of special aromatic sulfonates. [For example, demol C (formalin condensate of creosote oil sulfonate)], a block copolymer of ethylene oxide and propylene oxide, which are nonionic activators, and an ethylene oxide adduct of alkylphenol.

Next, the operation of recording an image on the recording medium F with the ink jet printer of FIG. 1 will be described. First, the recording unit 10 ejects ink from the serial head 6 onto the recording medium F conveyed from the roll body 9 of FIG. 1 to perform image recording. At this time, the serial head 6 ejects the respective inks of M for the nozzle row 6a, C for the nozzle row 6b, and Y for the nozzle row 6c, so that the respective inks of M, C, and Y are ejected.
Are ejected onto the recording medium F in the order of M, C,
Since the inks of the respective colors land in the order of Y, the images are recorded on the recording medium F in the order of M, C, and Y in the overlapping order of the colors.

When ink of a low lightness is superposed on ink of a high lightness, the image appears to be dark, and therefore the order of ejecting the inks of M and C is changed to C, It may be M or Y.

It is also possible to add a nozzle array with the serial head of FIG. 2 and perform image recording with four colors of KYMC using K ink. In this case, the K of the color with the lowest lightness is used.
It is desirable to eject the ink first and eject the Y ink of the color having the highest lightness last. That is, K, M,
An image can be recorded by ejecting each ink in the order of C, Y or in the order of K, C, M, Y.

Next, the recording medium F has a pair of conveying rollers 15.
a, 15b are conveyed in the conveying direction S through the accumulation portion 18, cut by the cutting portion 40 to a predetermined size at an appropriate position, and then conveyed to the fixing portion 50 by the conveying roller pair 16a, and the fixing portion 50. It enters between the heating roller 51 and the pressure roller 52. Then, under the control of the control unit 20, the heating roller 51 is heated to a predetermined temperature and driven in the direction A so as to have a predetermined pressure, whereby the recording medium F on which the image is written is heated on the heating roller 51 and the pressure roller 5.
The nip portion 59 formed between the first and second portions is heated / pressurized at the predetermined temperature and the predetermined pressure as described above, and the time for passing through the nip portion 59 is controlled.

As described above, the recording medium F is transferred to the fixing unit 50.
By heating and pressurizing, the latex particles contained in the uppermost surface layer 73 of the recording medium F of FIG. 5 are melted and smoothed to be transparent, and the ink is absorbed in the ink absorbing layer 72 to thereby absorb the recording medium. The image is fixed on the recording medium F, and the image clarity value of the image formed on the recording medium F is 60% to 95% when at least one of the heating temperature, the pressing force, and the heating / pressurizing time of the recording medium F at this time is fixed. It is controlled to be within the range.

That is, the heating temperature T of the recording medium F is T = Tg
± ΔT = 50 to 150 ° C. ± 10 ° C.
The pressure applied to the recording medium F by the heating roller 51 is set to 9.
It is included in the surface layer 73 of the recording medium F of FIG. 5 by controlling the image clarity value of the image within 60% to 95% by controlling so as to be 8 × 10 ^{4 to} 4.9 × 10 ⁶ Pa. By melting the latex particles to smooth and smooth the surface layer 73 to make it transparent, it is possible to obtain a glossy appearance similar to that of a photograph and to form a high quality image, and at the same time, ink is taken into the ink absorbing layer 72 to cause color fading. It is possible to prevent deterioration of the gray balance during image storage, and it is possible to form an image having excellent storage stability.

Further, it is preferable to use a dye ink as the ink, because the color reproducibility is particularly good. Further, regarding the fading property, the ink solvent absorbing layer 62 is taken in and covered with the latex layer to improve the storage stability. it can. In addition, when the pigment ink is used, especially the image storability (not brown,
(No bleeding) is preferable, and gloss and texture can be improved as described above.

When the image clarity value is 60% or less, the gloss peculiar to the photograph is reduced and the image quality is deteriorated. When the image clarity value is 95% or more, the image is abnormally shiny and the image quality is deteriorated. Since it is easy to get it, the range of 60% to 95% is preferable.

As described above, by ejecting the inks from the nozzle rows 6a to 6c of the serial head 6 so that the overlapping order of the colors is always the same, the colors reproduced by the inks are constant and do not vary. And the color reproducibility is improved.
When gray is created by superimposing YMC colors, the order described above improves graininess and makes it difficult for the gray balance to be lost. Further, it is preferable that the order of superimposing each color is such that the color having the low lightness is first and the color having the high lightness is the latter so that the range of color reproducibility is widened.

<Second Embodiment>

The second embodiment is an ink jet printer having the same structure as that shown in FIG. 1, but uses two kinds of light and shade inks for K of four YMCK colors. Therefore, in the inkjet printer according to the present embodiment, the line head 1 shown in FIG.
1 is added to each color of YMC, and two types of K are provided for light and shade. The line head 11 of FIG. 7 is separated so that the nozzle surface 61 faces the recording medium F as shown in FIG. 1, and the nozzle surface 61 of FIG. 2 extends in a direction orthogonal to the transport direction S of the recording medium F of FIG. It is arranged to extend. On the nozzle surface 61 of FIG. 2, a large number of nozzles 1 a for respectively ejecting ink extend in a row to form a nozzle row 62. Recording unit 10
, Each line head 11 is independently driven,
From the total of 5 nozzle rows of each line head 11, Y, M,
By ejecting C, dark K, and light K inks onto the recording medium F, a color image can be formed on the recording medium F.

As described above, two or more kinds of K having different concentrations are used.
By forming an image with each color ink including ink, the graininess of gray is improved, and in particular, the graininess of a light gray color such as a wedding dress is improved. Also,
As in the first embodiment, the heating temperature T of the recording medium F is controlled so that T = Tg ± ΔT = 50 to 150 ° C. ± 10 ° C., and the pressure applied to the recording medium F by the heating roller 51 is set to 9 °. By controlling the image clarity value of the image to be within the range of 60% to 95% by controlling so as to be 0.8 × 10 ^{4 to} 4.9 × 10 ⁶ Pa, the surface layer 73 of the recording medium F in FIG. By melting the latex particles contained and smoothing the surface layer 73 to make it transparent, it is possible to obtain a glossy image similar to that of a photograph and form a high-quality image, and at the same time, the ink is taken into the ink absorbing layer 72 and The fading property is improved, it is possible to prevent the gray balance from being lost during image storage, and it is possible to form an image having excellent storage properties. Further, dye ink and pigment ink can be used as the ink, and the same effect as described above can be obtained.

Next, another example of the structure of the fixing unit 50 shown in FIG. 1 will be described with reference to FIG. FIG. 6 is a side view showing the endless belt type fixing unit in detail.

The fixing section in FIG. 6 is constructed so as to pressurize and heat the recording medium F while being conveyed by the endless belt, and as shown in the drawing, the heating roller 410 and the recording medium F.
And a pressure roller 44 for sandwiching the heat roller 410 with the heating roller 410.
0, a driven roller 420 disposed on the downstream side, an endless heating belt 430 stretched between the heating roller 410 and the driven roller 420, and a recording medium F heating belt 4.
A pressing unit 470 for pressing the heating belt 30 and a temperature sensor 480 for detecting the surface temperature of the heating belt 430.
A transport sensor 490 that detects the recording medium F on the upstream side of the heating roller 410 and the pressure roller 440, and a cleaning unit 600 that removes ink stains adhering to the surface of the heating belt 430.

The heating roller 410 is composed of a hollow roller and has a heating element 450 such as a halogen heater as a heat source built therein along its axial direction. The heating roller 450 heats the heating roller 410, and the heating roller 410 is suspended on it. Heating belt 4
By heating 30 as well, the recording medium F pressed by the heating belt 430 is heated, and the thermoplastic resin particles on the surface layer thereof are melted. The heating roller 410 is a heating element 45.
The recording medium F is preferably formed of a material having a high thermal conductivity so that the recording medium F can be efficiently heated by the heat generated from 0, and it is preferably formed of a metal roller.

The temperature sensor 480 is arranged close to the heating roller 410, detects the surface temperature of the heating belt 430, and the control unit 20 of FIG. 4 causes the heating element 450 inside the heating roller 410 to detect the surface temperature of the heating belt 430. Of the heating belt 430 is controlled to maintain the surface temperature of the heating belt 430 within a predetermined temperature range. The heating element 450 is the heating roller 41.
It may be provided near the outside of 0.

The heating belt 430 is suspended between the heating roller 410 and the driven roller 420, and after being heated to a predetermined temperature range by the heating element 450, the recording medium F on which an image is recorded is pressed to record. The thermoplastic resin particles contained in the surface layer of the medium F are melted, and the surface roughness of the recording medium F becomes approximately the same as the surface roughness of the heating belt 430.

Therefore, the outer surface (on the recording medium side) of the heating belt 430 is required to have a small surface roughness. Specifically, Ra = 0.5 μm or less and 0.01 μm or more (preferably, Ra). Ra = 0.1 μm or less) is required. Here, to describe the incidental effect of reducing the surface roughness of the belt, generally, for the same material, the smaller the surface roughness, the higher the abrasion resistance and the higher the durability. Are known. Further, it is known that the smaller the surface roughness is, the more excellent the antistatic property and the prevention of the offset are. Therefore, such an effect can be obtained in FIG. 6.

The heating belt 430 is basically a metal belt or resin belt whose surface is coated, and in consideration of the releasability from the recording medium F and the surface roughness when coated, The following materials are preferred.・ Nickel Belt + Silicon Rubber + PFA ・ Nickel Belt + PFA ・ Nickel Belt + Silicon Rubber ・ Nickel Belt + Fluorine Coat ・ Nickel Belt + Silicon Rubber + Hardened Silicon ・ Nickel Belt + Hardened Silicon ・ Stainless Steel Belt + Silicon Rubber + PFA ・ Stainless Steel Steel Belt + PFA-Stainless Steel Belt + Silicon Rubber-Stainless Steel Belt + Fluorine Coated-Stainless Steel Belt + Silicon Rubber + Hardened Silicon-Stainless Steel Belt + Hardened Silicon-Polyimide Belt + Silicon Rubber + PFA-Polyimide Belt + PFA-Polyimide Belt + Silicon Rubber / Polyimide Belt + Fluorine Coated / Polyimide Belt + Silicon Rubber + Curing Silicon / Polyimide Belt + Curing Silicon

The pressure roller 440 is composed of a metal roller of stainless steel or the like, or a metal roller of stainless steel or the like having an outer periphery coated with elasticity, and is provided on the heating roller 410 side by an urging means (not shown). Is constantly pressed. When the conveyance sensor 490 provided on the upstream side of the heating roller 410 and the pressure roller 440 detects the conveyance of the recording medium F, the urging means pushes the pressure roller 440 against the heating roller 410 in the control unit 20 of FIG. Control such as weakening the pressure is performed. This prevents the end surfaces of the recording medium F from damaging the surfaces of the heating belt 430 and the pressure roller 440.

The pressing means 470 is a plate-shaped member 471 in contact with the lower surface of the recording medium F in the drawing, and a biasing means 47 for biasing the plate-shaped member 471 and the recording medium F toward the heating belt 430.
2 and. The plate-shaped member 471 is preferably made of metal, and its surface roughness is required to be as small as that of the heating belt. Specifically, Ra = 0.5 μ.
m or less and 0.01 μm or more (preferably Ra =
0.1 μm or less) is required. Urging means 4
72 is composed of a spring or the like, and a plurality of them may be provided, and it is possible to adjust the pressing force (pressing force) against the recording medium F. It is preferable to dispose a pressure sensor as in FIG. 3 for detecting the applied pressure.

Further, the heating roller 410 and the driven roller 42
By arranging the auxiliary heating element 451 and the temperature sensor 452 therefor inside the heating belt 430 between 0 and 0, the heating temperature for the recording medium F can be controlled more accurately.

In FIG. 6, when the recording medium F on which an image is recorded with ink is conveyed in the conveying direction S,
The conveyance sensor 490 detects the recording medium F, and the pressure roller 4
After weakening the pressing force of the heating roller 410 of 40,
The recording medium F enters between the heating belt 430 and the pressure roller 440 and moves in the transport direction S.
0 and the plate-shaped member 471 are conveyed. During this conveyance, the recording medium F is heated by the heating belt 430, and the spring 47 of the biasing means 470 is passed through the plate member 471.
It receives pressure from 2. The image clarity value of the image formed on the recording medium F is 60% to 95% for at least one of the heating temperature and the pressing force by the control unit 20 of FIG.
It is controlled to be within the range. Further, the endless belt system of FIG. 6 is preferable in this respect because it can secure a longer heating time and pressurizing time than the rotary roller system of FIG.

[0173]

EXAMPLES The present invention will be further described with reference to Examples and Comparative Examples.

<< Preparation of Recording Medium >> Samples F1 and F2 of recording media as ink jet recording sheets were prepared by the following procedure.

[Preparation of Inorganic Fine Particle Dispersion]

(Preparation of Silica Dispersion Liquid 1) 125 kg of vapor-phase process silica (QS-20 manufactured by Tokuyama Corp.) having an average primary particle size of about 0.012 μm was used as a jet stream by Mitamura Riken Kogyo Co., Ltd. Inductor mixer TD
After S was dispersed by suction in 620 L of pure water whose pH was adjusted to 2.5 with nitric acid at room temperature, the total amount was 694 L with pure water.
After that, a silica dispersion liquid 1 was prepared.

(Preparation of silica dispersion 2) [Chemical formula 1]
69.4 L of the silica dispersion liquid 1 prepared above is added to 18 L of an aqueous solution (pH = 2.3) containing 1.14 kg of the cationic polymer (P-1), 2.2 L of ethanol, and 1.5 L of n-propanol. The mixture was added with stirring, then 7.0 L of an aqueous solution containing 260 g of boric acid and 230 g of borax was added, and 1 g of an antifoaming agent SN381 (manufactured by San Nopco Ltd.) was added. This mixed solution was dispersed with a high pressure homogenizer manufactured by Sanwa Kogyo Co., Ltd., and the total amount was adjusted to 97 L with pure water to prepare a silica dispersion 2.

[0178]

[Chemical 1]

[Preparation of Thermoplastic Resin Coating Liquid 1] A styrene-acrylic latex polymer (Tg 78 ° C., average particle size 0.3 μm, solid content concentration 40%) emulsion-polymerized using a nonionic surfactant as an emulsifier % Nitric acid aqueous solution to adjust the pH to 4.7, and this was used as a thermoplastic resin coating liquid 1.

[Preparation of coating liquid]

After preparing the coating liquid as described below, the coating liquid was applied to a commercially available filter (TC manufactured by Toyo Roshi Kaisha, Ltd.).
It filtered using P10 or TCP30).

(Preparation of Lower Layer Coating Liquid 1) While stirring at 40 ° C., 710 ml of the silica dispersion 2 prepared above was sequentially mixed with the following additives to prepare a lower layer coating liquid 1.

10% aqueous solution of polyvinyl alcohol (Kuraray Industry Co., Ltd .: PVA203) ... 3 ml Polyvinyl alcohol (Kuraray Industry Co., Ltd .: PVA)
235) 4.8% and polyvinyl alcohol (Kuraray Industry Co., Ltd .: PVA
An aqueous solution containing 1.84% of 245) ... 273 ml The total volume was adjusted to 1000 ml with pure water.

(Preparation of Upper Layer Coating Liquid 1) The thermoplastic resin coating liquid 1 and the lower layer coating liquid 1 prepared above were mixed so that the solid content ratio of the thermoplastic resin and the inorganic pigment was 40:60. Thereafter, water was added so that the viscosity at 43 ° C. was 45 mPa · s, and this was used as upper layer coating liquid 1.

(Preparation of Upper Layer Coating Liquid 2) Above upper layer coating liquid 1
In the preparation of, the upper layer coating liquid 2 was prepared in the same manner except that the solid content ratio of the thermoplastic resin and the inorganic pigment was changed to 50:50.

[Preparation of Recording Medium]

A paper support whose both sides are coated with polyethylene (also referred to as RC paper, has a thickness of 220 μm, and the polyethylene of the ink absorbing layer surface has a polyethylene content of 13 to polyethylene).
1% by weight of the anatase-type titanium oxide) from the support side to the lower layer coating solution 1 as a first layer.
72 μm, the upper layer coating liquid 1 (average particle diameter of the thermoplastic resin: 0.3 μm) as the second layer, under the condition that the wet film thickness is 60 μm and the solid content of the thermoplastic resin is 3.0 g / m ² ,
Two layers were simultaneously coated and dried using a slide hopper. Each coating solution was heated to 40 ° C. for coating, and immediately after coating, it was cooled for 20 seconds in a cooling zone kept at 0 ° C.
Sequentially dry for 60 seconds with 25 ° C wind (15% relative humidity), 45 seconds with 45 ° C wind (25% relative humidity), and 60 seconds with 50 ° C wind (25% relative humidity), and then 20-25 After conditioned for 2 minutes in an atmosphere of 40 ° C and 60 ° C relative humidity,
The sample was wound to prepare a sample F1. Then, the sample F1 was enclosed in a polyethylene bag and subjected to aging treatment at 55 ° C. for 3 days.

The wet film thickness of the first layer is 184 μm, the upper layer coating solution 2 is used in the second layer, and the wet film thickness is 40 μm.
m, a sample F2 was prepared in the same manner as the above-described sample F1 except that the solid content rate of the thermoplastic resin was changed to 2.5 g / m ^2, and then the same aging treatment was performed.

<< Preparation of Ink >>

A water-based pigment ink was prepared by the following procedure.

[Preparation of Water-based Pigment Ink]

(Preparation of Pigment Dispersion) <Preparation of Yellow Pigment Dispersion 1> C.I. I. Pigment Yellow 74 ... 20% by mass Styrene-acrylic acid copolymer (molecular weight 10,000,
Acid value 120) ... 12% by mass Diethylene glycol ... 15% by mass Ion-exchanged water ... 53% by mass A horizontal bead mill in which the above-mentioned additives are mixed and 0.3 mm zirconia beads are filled at a volume ratio of 60%. (System Zetamini manufactured by Ashizawa Co., Ltd.) was used to obtain yellow pigment dispersion 1. The average particle size of the obtained yellow pigment was 112 nm.

<Preparation of Magenta Pigment Dispersion 1> C.I. I. Pigment Red 122 ... 25% by mass John Kryl 61 (acrylic-styrene resin, manufactured by Johnson Co.) ... 18% by mass in solid content Diethylene glycol ... 15% by mass Ion-exchanged water ... 42% by mass The additives were mixed and dispersed using a horizontal bead mill (System Zetamini manufactured by Ashizawa Co., Ltd.) filled with 0.3 mm zirconia beads at a volume ratio of 60% to obtain Magenta pigment dispersion 1. The average particle size of the obtained magenta pigment was 105 nm.

<Preparation of Cyan Pigment Dispersion 1> C.I. I. Pigment Blue 15: 3 ... 25% by mass John Cryl 61 (acrylic-styrene resin, manufactured by Johnson) ... 15% by mass as solid content Glycerin ... 10% by mass Ion-exchanged water ... 50% by mass The above additives were mixed and dispersed using a horizontal bead mill (System Zetamini manufactured by Ashizawa Co., Ltd.) filled with 0.3 mm zirconia beads at a volume ratio of 60% to obtain a cyan pigment dispersion 1. The average particle size of the obtained cyan pigment is 87.
was nm.

<Preparation of Black Pigment Dispersion 1> Carbon black ... 20% by mass Styrene-acrylic acid copolymer (molecular weight 7,000, acid value 150) ... 10% by mass Glycerin ... 10% by mass Ion-exchanged water: 60% by mass Disperse the above additives with a horizontal bead mill (System Zetamini manufactured by Ashizawa Co., Ltd.) filled with 0.3 mm zirconia beads at a volume ratio of 60% to disperse a black pigment. I got body 1. The average particle size of the obtained black pigment was 75 nm.

(Preparation of Pigment Ink)

<Preparation of Yellow Ink> Yellow Pigment Dispersion 1 ... 15% by mass Ethylene glycol ... 20% by mass Diethylene glycol ... 10% by mass Surfactant (Surfynol 465, Nissin Chemical Industry Co., Ltd.)
... 0.1% by mass Ion-exchanged water ... 54.9% by mass The above compositions were mixed, stirred, and filtered through a 1 µm filter to prepare a yellow ink which is an aqueous pigment ink. The average particle size of the pigment in the ink was 120 nm, and the surface tension γ was 36 mN / m.

<Preparation of Magenta Ink> Magenta Pigment Dispersion 1 ... 15% by mass Ethylene glycol ... 20% by mass Diethylene glycol ... 10% by mass Surfactant (Surfynol 465 Nissin Chemical Industry Co., Ltd.)
... 0.1% by mass Ion-exchanged water ... 54.9% by mass The above compositions were mixed, stirred, and filtered through a 1 µm filter to prepare a magenta ink that is an aqueous pigment ink. The average particle size of the pigment in the ink was 113 nm, and the surface tension γ was 35 mN / m.

<Preparation of cyan ink> Cyan pigment dispersion 1 ... 10% by mass Ethylene glycol ... 20% by mass Diethylene glycol ... 10% by mass Surfactant (Surfynol 465, Nissin Chemical Industry Co., Ltd.)
... 0.1% by mass Ion-exchanged water ... 59.9% by mass The above compositions were mixed, stirred, and filtered through a 1 µm filter to prepare a cyan ink that is an aqueous pigment ink.
The average particle diameter of the pigment in the ink was 95 nm, and the surface tension γ was 36 mN / m.

<Preparation of Black Ink> Black Pigment Dispersion 1 ... 10% by mass Ethylene glycol ... 20% by mass Diethylene glycol ... 10% by mass Surfactant (Surfynol 465, Nissin Chemical Industry Co., Ltd.)
... 0.1% by mass Ion-exchanged water ... 59.9% by mass The above compositions were mixed, stirred, and filtered through a 1 µm filter to prepare a black ink that was an aqueous pigment ink. The average particle size of the pigment in the ink was 85 nm, and the surface tension γ was 35 mN / m.

Further, the following water-based dye ink was prepared.

[Preparation of Water-based Dye Ink]

[0203]   <Preparation of yellow ink> C. I. Direct ye11ow 86 5% Triethylene glycol 15% Triethylene glycol monobutyl ether 15% Remaining water

[0204]   <Preparation of magenta ink> C. I. Acid Red 249 5% Glycerin 5% Triethylene glycol monomethyl ether 15% Remaining water

[0205]   <Preparation of cyan ink> C. I. Direct Blue 199 3% PEG # 200 5% Olfine E1010 (Nissin Chemical) 15% Remaining water

[0206]   <Preparation of black ink> C. I. Direct Black 168 7% Glycerin 10% Triethylene glycol monobutyl ether 10% Remaining water

<First Embodiment>

Next, each of the samples F1 and F of the recording medium described above
1 and 2 as Examples 1 to 4 and Comparative Example 1 using the above-described water-based pigment ink and water-based dye ink.
(Or FIG. 8) Under the following conditions, a gray gradation (a pattern in which the color gradually changes from white to black) and a photograph of a person were printed and evaluated under the following conditions. The evaluation results are shown in Table 1.

Example 1: One-way printing was performed in the main scanning direction T of FIG. 2 by ejecting ink in the order of M, C and Y in FIG.

Example 2 In FIG. 2, ink was ejected in the order of C, M, and Y to perform one-way printing in the main scanning direction T of FIG.

Comparative Example 1 Ink was ejected in the order of M, C and Y in FIG. 2 to perform bidirectional (reciprocal) printing in the main scanning direction T and the reverse direction of FIG.

Example 3: In FIG. 8, nozzle rows were formed in the order of MCYYCM, and ink was ejected in the order of M, C, Y, Y, C, and M for all ejections for reciprocal printing.

Example 4 In FIG. 8, heads were arranged in the order of MCYYCM, and ink was ejected in the order of M, C, and Y by the first three ejections in the scanning direction to perform reciprocal printing.

[0214]

[Table 1]

From Table 1, in each of Examples 1 to 4, the reproducibility of the gray portion was good, and the reproducibility of vivid colors was good. Further, in Examples 1 and 2, the printing speed is not improved because the printing is performed in only one direction as compared with Comparative Example 1, but in Example 3, the number of nozzles is large and all of them are used for bidirectional printing. The print speed is higher than that of Comparative Example 1. In Example 4, the number of nozzles is large, but only half of the nozzles are used at the same time, and printing is performed bidirectionally with substantially the same number of nozzles as in Comparative Example 1, so the printing speed is the same as in Comparative Example 1. On the other hand, in Comparative Example 1 in which the ink is ejected in the order of M, C, and Y in the direction T of FIG. 2 and the ink is ejected in the order of Y, C, and M in the opposite direction, the gray portion is colored. The reproducibility of the gray part was not good.

<Second Embodiment>

Next, as a second example, black dark ink and black light ink were prepared as follows.

<Preparation of Black Dark Ink> Black Pigment Dispersion 1 10% by mass Ethylene glycol 20% by mass Diethylene glycol 10% by mass Surfactant (Surfynol 465 Nisshin Chemical Industry Co., Ltd.) 0.1% by mass ion-exchanged water 59. 9% by mass or more of each composition was mixed, stirred, and filtered with a 1 μm filter to prepare Black Dark Ink 1 which is the aqueous pigment ink of the present invention. The average particle diameter of the pigment in the ink is 85 nm
And the surface tension γ was 35 mN / m.

<Preparation of Black Light Ink> Black Pigment Dispersion 1 2% by mass Ethylene glycol 25% by mass Diethylene glycol 10% by mass Surfactant (Surfynol 465, Nissin Chemical Industry Co., Ltd.) 0.1% by mass ion-exchanged water 62. 9% by mass or more of each composition was mixed, stirred, and filtered through a 1 μm filter to prepare Black Light Ink 1 which is the aqueous pigment ink of the present invention. The average particle size of the pigment in the ink is 89 nm
And the surface tension γ was 36 mN / m.

For each of the samples F1 and F2 of the above-mentioned recording medium, the black dark ink, the black light ink, and the yellow ink, magenta ink, and cyan ink used in the first embodiment are used in the fifth embodiment and the fifth embodiment. Comparative Example 2,
3 was used to form an image under the following conditions using the inkjet printer of FIG.

The image processing parameters for replacing the YMC mixed color portion with K were adjusted so that the K ink was 25% of the total ink amount and the rest was YCM ink in the achromatic portion. Regarding the K ink, in Example 5, the light portion was K light ink, the dark portion was K dark ink, and both inks were used in the middle density. In Comparative Example 2, only K dark ink was used, and in Comparative Example 3, only K light ink was used. Under this condition, a gray gradation (a pattern in which the color gradually changes from white to black) and a photograph of a person were printed and evaluated.
The evaluation results are shown in Table 2.

[0222]

[Table 2]

As can be seen from Table 2, in Example 5, the reproducibility of the gray portion, the rough feeling of the gray portion and the high density black portion were all good, but in Comparative Example 2, the gray portion was rough. In Comparative Example 3, there was a lack of density in the high density black area, and for example, the hair was not clean.

Although the present invention has been described above with reference to the embodiments, the present invention is not limited to these.
Various modifications are possible within the scope of the technical idea of the present invention. For example, the head configuration is not limited to the serial head shown in FIGS. 2 and 8, and may be a line head as shown in FIG. That is, the line head 11 of FIG. 7 has a nozzle row 62 in which the nozzles 1a are arranged in one row on the nozzle surface 61, and a plurality of line heads 11 can be arranged so as to eject ink in the order of MCY, for example. In addition, K light ink, K
The line head 11 can be additionally arranged for dark ink.

[0225]

According to the present invention, when fading of ink is improved, color reproducibility is improved, and when gray is formed by superimposing inks of a plurality of colors, a gray balance is good and the gray level is similar to that of a photograph. An image recording method and an inkjet printer that can obtain image quality can be provided.

Further, by improving the color fading properties of the ink and forming an image with each color ink containing two or more kinds of K inks having different densities, the graininess of gray is improved, and a good gray balance is obtained. It is possible to provide an image recording method and an inkjet printer that can obtain the same image quality.

[Brief description of drawings]

FIG. 1 is a side view schematically showing an inkjet printer according to an embodiment.

FIG. 2 is a perspective view showing a schematic configuration of the serial head of FIG.

FIG. 3 is a side view showing the fixing unit of the inkjet printer of FIG. 1 in more detail.

FIG. 4 is a block diagram showing a control system of the inkjet printer of FIG.

FIG. 5 is a cross-sectional view showing a laminated structure of the recording medium according to the present embodiment.

FIG. 6 is a side view showing another configuration example of the fixing unit in FIG.

FIG. 7 is a perspective view of a line head that can be arranged as an ink head of the inkjet printer of FIG.

FIG. 8 is a perspective view schematically showing another configuration of the serial head of FIG.

[Explanation of symbols]

6,8 serial head 9 rolls 10 Recording section 11 line head 1a nozzle 20 Control unit 23 Head drive circuit 26 Fixing unit drive mechanism 40 cut section 50 fixing unit 51 heating roller 53 heating element 52 Crimping roller 55 Temperature sensor 71 Support for recording medium F 72 Ink absorption layer of recording medium F 73 surface of recording medium F F recording medium S movement direction Main scanning direction of T serial head

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Claims (11)

[Claims] 1. An image is recorded on a recording medium having an ink absorption layer on a support and a thermoplastic resin on the surface thereof while ejecting inks of respective colors so that the order of superposition of a plurality of colors is always the same. , And the image clarity value of the image formed on the recording medium thereafter is 6
An image recording method characterized in that an image is recorded by heating and pressurizing the recording medium so as to be 0% or more and 95% or less. 2. The image recording method according to claim 1, wherein the inks of the respective colors are ejected in order of the color having the lowest brightness. 3. The ink of each color is ejected in the order of M, C, Y or in the order of C, M, Y when each of the plurality of colors includes each color of YMC.
The image recording method described in. 4. An image is recorded by ejecting each color ink containing two or more kinds of K ink having different densities onto a recording medium having an ink absorption layer on a support and a thermoplastic resin on the surface. After that, the image clarity value of the image formed on the recording medium is 6
An image recording method characterized in that an image is recorded by heating and pressurizing the recording medium so as to be 0% or more and 95% or less. 5. The image clarity value is set to 60% or more and 95% or less by controlling at least one of a heating temperature, a pressing force, and a heating / pressurizing time when the recording medium is heated and pressed. 5. The method according to claim 1, wherein
The image recording method described in the item. 6. The image recording method according to claim 1, wherein the surface layer of the recording medium further contains an inorganic pigment. 7. An ink head for ejecting a plurality of inks onto a recording medium, and a heating / pressurizing means for heating and pressurizing the recording medium after ejecting the inks are provided, and an image is recorded on the recording medium. An inkjet printer, which ejects ink of each color from the ink head so that a plurality of colors are always superposed in the same order on the recording medium having an ink absorption layer on a support and a thermoplastic resin on a surface layer However, the image clarity value of the image formed on the recording medium thereafter is 6
An inkjet printer, wherein the recording medium is heated and pressed by the heating and pressurizing device so that the recording medium is 0% or more and 95% or less. 8. The ink jet printer according to claim 7, wherein the inks of the respective colors are ejected in the order of the color having the lowest brightness. 9. The ink of each color is ejected in the order of M, C, Y or in the order of C, M, Y when each of the plurality of colors includes each color of YMC.
The inkjet printer described in 1. 10. An ink head for ejecting a plurality of inks onto a recording medium, and a heating and pressurizing means for heating and pressurizing the recording medium after ejecting the inks, wherein an image is recorded on the recording medium. An ink jet printer, which ejects each color ink containing two or more kinds of K ink having different densities from the ink head onto the recording medium having an ink absorption layer on a support and a thermoplastic resin on the surface layer. Image is recorded on the recording medium, and then the image clarity value of the image formed on the recording medium is 6
An inkjet printer, wherein the recording medium is heated and pressed by the heating and pressurizing device so that the recording medium is 0% or more and 95% or less. 11. The heating / pressurizing means is configured to control at least one of a heating temperature, a pressing force, and a heating / pressurizing time at the time of heating and pressurizing the recording medium. Item 11. The inkjet printer according to any one of items 7 to 10.