JP2003182203A - Method and apparatus for inkjet recording and treating agent - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for inkjet recording by which a double-side copying is possible by decreasing concentration of a back surface even when a plain paper is used, to provide a method for recording with no unpleasant striking-through even when the double-side copying is not performed, and or to provide a method for contributing to make quality of a recording image higher and to provide a method for eliminating a granular feeling especially on a photographic image and a method for improving water resistance and light resistance. <P>SOLUTION: A method for inkjet recording by which an image is recorded by ejecting ink drops on a recording medium is characterized by providing a treating agent from a back surface side in the neighborhood of a recording part on the whole or a part of the recording part before or after or simultaneously printing is performed on a recording face. <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 ink jet recording method, an ink jet recording apparatus and a treating agent,
In particular, the present invention relates to an inkjet recording method, an inkjet recording apparatus, and a treatment agent capable of recording an image without strike-through on plain paper on which ink easily strikes. further,
In particular, the present invention relates to an inkjet recording method, an inkjet recording apparatus, and a treatment agent that prevent occurrence of graininess in a low-density image portion of a photographic image. Further, the present invention relates to an ink jet recording method, an ink jet recording apparatus, and a treatment agent that improve weather resistance such as water resistance or light resistance of an image. The strike-through means here that the front image can be recognized from the back side on plain paper or the like. Not only when the colorant comes out on the back side, but also when the front side image can be seen through from the back side. The image density measured on the back surface at that time is called back surface density. Here, the recording medium is
Papers on which the front side image is likely to appear on the back side, and generally called plain papers including copy papers and recycled papers are shown.

[0002]

2. Description of the Related Art As an ink jet recording method, various methods have been proposed so far, and development has been carried out in search of an optimum ink for each recording medium.
However, since the ink stability, which is the required characteristic of the ink, and the required characteristic from the recorded image often conflict with each other, the desired image characteristic cannot be usually obtained. Therefore, there has been proposed a method of pre-coating or pre-applying the treatment liquid on the recording medium for the purpose of treating the recording medium in advance (Japanese Patent Laid-Open Nos. 63-293064 and 63-29997).
No. 1 (Patent Registration No. 2667401), JP-A-63
-299992 gazette (patent registration 2675001
No. 1) -69381 (Patent Registration No. 271)
1098), etc.). However, it was difficult to satisfy the purpose even with a specific treatment liquid.

As a recent trend, the quality when printed on generally called plain paper including copy paper and recycled paper is emphasized. The quality required for plain paper printing is that the printed matter has high image quality (no feathering) and high color development on the one hand, and on the other hand, bleeding caused by the contact of multiple color recording inks. (Ie, color bleed) is absent. Further, water resistance, light resistance and gas resistance of the image are naturally required.

Of these, what is particularly required is a reduction in the back surface density when printing on plain paper, a reduction in graininess, or an improvement in the water resistance and light resistance of an image. However, the current situation is that a satisfactory image cannot be obtained, particularly with respect to the reduction of the back surface density.

On the other hand, conventional apparatuses for recording on both sides of a recording medium are described in Japanese Patent Application Laid-Open Nos. 10-329311 and 11-277723. However, this is for recording on both sides of a transparent medium such as OHP, and is completely different from the object of the present invention. In addition, JP-A-11-
Japanese Patent No. 315484 similarly discloses a method of inkjet printing from both sides in inkjet printing onto a cloth or the like. However, this improves the recognition of the recorded image from the back surface and is not intended to reduce the recognition of the recorded image from the back surface.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide an ink jet recording method capable of double-sided copying by improving the above-mentioned characteristics to reduce the back side density, especially on plain paper, and double-sided copying. Providing an unpleasant strike-through recording method even when not performing
Alternatively, it is to provide a method that contributes to high quality of a recorded image. Another object of the present invention is to provide a method for eliminating graininess, particularly for photographic images, and a method for improving water resistance, light resistance and the like.

[0007]

The present inventors have solved the above problems by applying a treatment agent to the printing portion of the recording surface from the back side of the recording surface before or after printing, or at the same time. did.

[0008] That is, the above-mentioned problem is (1) of the present invention.
"In an inkjet recording method of recording an image by ejecting ink droplets onto a recording medium, before or after printing on a recording surface, or at the same time, in all or a part of the recording portion from the back surface side in the vicinity of the recording portion. Inkjet recording method characterized by applying a treating agent ", (2)" Inkjet recording method described in the above item (1), characterized in that both sides of a recording medium are used as recording surfaces to print an image. " ,
(3) "The printing heads are provided on both sides of the recording medium conveyance path, and the printing heads are provided on the both sides.
Inkjet recording method according to item 4, item (4), wherein the treatment agent contains a material that reduces the degree to which a recorded image is recognized from the back side. Inkjet recording method according to any one of items (3), (5), wherein the processing agent has a function of reducing the graininess of a recorded image. Or (6) "corresponding to the image portion printed on the back surface when printing the image on both surfaces of the recording medium or when printing the front surface. Any one of the above items (1) to (5), characterized in that the treatment agent is applied in advance to the portion and the treatment agent is applied to the portion corresponding to the image portion of the front surface when the back side is printed. Inkjet recording method described in "," (7) "Surface image during surface printing (1) to (5), wherein the colored ink is applied after applying the treating agent to the ink, and the colored ink is applied after applying the same treating agent to the back side image portion at the time of printing on the back side. (8) The inkjet recording method according to any one of (1) to (8), wherein the treatment agent contains at least a polyvalent metal salt. The inkjet recording method according to any one of items 1 to 7, wherein the treatment agent contains at least a cationic compound. (10) "The ink jet recording method according to any one of the items (1) to (7), wherein the treating agent contains at least an inorganic oxide".
“The inkjet recording method according to any one of the above items (1) to (7), wherein the treatment agent contains at least a white or light yellow resin”.

Further, the above problem can be achieved by (12) "an ink jet printer device characterized by performing recording by the recording method according to any one of the items (1) to (7)". .

The effects of applying the treatment agent from the back surface are various, such as reducing the back surface density (preventing strike-through), reducing the graininess of the image, and improving the light resistance of the image. However, since the effect to be exerted differs depending on the type of treating agent, it is necessary to select an appropriate treating agent according to the purpose. In addition, since the treating agent is generally applied as a treating liquid here, the treating agent may be referred to as a treating liquid. In order to reduce the back surface density, the processing agent must be a material of the same color as the recording medium, and if the medium is white paper, it will become white after drying Polyvalent metal salt, metal oxide, white or pale yellow Resins of the above are preferable. Further, when the medium is thin such as plain paper and the colorant for the front surface image comes into contact with the backside treatment liquid, a material that easily reacts with the colorant in the image area has a high effect of reducing the backside density. Further, when the surface printing colorant and the back surface treatment liquid come into contact with each other in this way, it is more effective to reduce the back surface image by printing the front surface image after applying the back surface treatment agent as the printing order. On the other hand, image weather resistance,
In particular, in order to exert the effect of water resistance, it is necessary that the treating agent has the ability to make the coloring agent to be printed on the surface contact with the backside treating solution in the medium to react with each other to make the coloring agent insoluble in water. When using an anionic colorant, the treatment agent is a cationic compound,
Polyvalent metal salts and cationic metal oxides are effective.
In order to improve light resistance, it is advisable to add an antioxidant and an ultraviolet absorber to the back surface treatment liquid.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 are schematic configuration diagrams of an inkjet recording apparatus according to the present invention. In the ink jet recording apparatus shown in FIGS. 1 and 2, the guide rod (3) and the guide plate (4) horizontally arranged between the left and right side plates (1) and (2) cause the carriage (5) to move in the main scanning direction ( The carriage (5) is slidably held, and a recording head (6), which is an inkjet head, is mounted on the lower surface side of the carriage (5) with the ink droplet ejection direction facing downward. An ink tank (ink cartridge) (7) for supplying the ink of each color and the back surface treatment liquid is attached to the upper surface of the recording head (6).

The recording head (6), as shown in FIG.
Head (6u) for ejecting backside treatment liquid (U), head (6y) for ejecting yellow (Y) ink, head (6m) for ejecting magenta (M) ink, and cyan (C) ink The head (6c) for discharging and the head (6b) for ejecting black (K) ink are arranged in the main scanning direction. Each head (6u), (6y),
A large number of recording nozzles (8) are arranged in two rows in the sub-scanning direction at (6m), (6c), and (6b). The order of arranging the heads may be changed according to the purpose. In particular, the printing of the processing liquid on the back side is performed in order to print the processing liquid on the back surface near the printing portion of the recorded image by reversing the paper before or after printing the image on the recording surface, as opposed to when printing the recorded image. The head does not have to be arranged in succession with the colored ink head. In this case, the backside treatment liquid is printed by reversing the paper at a time different from that at the time of printing the image on the recording surface. Therefore, the backside treatment liquid should be printed so that it is a mirror image of the recorded image. become.

Here, the heads (6u), (6y),
(6m), (6c), and (6b) are as shown in FIG.
A nozzle forming member (1) in which a plurality of recording nozzles (8) are formed on the front surface of a liquid chamber forming member (11) forming the liquid chamber (10).
2) is provided, and the ink in the liquid chamber (10) is pressurized by the energy generating means such as a piezoelectric element and a heater for generating bubbles, which is not shown, so that the ink in the liquid chamber (10) is ejected from the nozzle forming member (12). ) Flying from the recording nozzle (8) as an ink droplet (13) and flying to the recording medium (hereinafter,
It will land as dots on the "paper". At this time, a desired image can be printed by selectively driving the energy generating means that applies pressure to each liquid chamber (10).

Returning to FIGS. 1 and 2, the carriage (5)
Is a main scanning motor (15) consisting of a stepping motor
Drive pulley (16) and driven pulley (17) rotated by
The carriage is connected to a timing belt (18) stretched between the carriage and the carriage, and the main scanning motor (15) is driven and controlled so that the carriage (5), that is, the recording head (6) is moved in the main scanning direction. ing.

On the other hand, in order to convey the paper (20) in the sub-scanning direction (the direction of arrow B in FIG. 2), a platen roller (hereinafter,
("Platen") (21) and Platen (2
A paper feed roller (22) arranged by being pressed against the peripheral surface of 1),
(23) and a pinch roller (2
4) and the recording head (6) face each other, a guide plate (25)
And a paper ejection roller (26) downstream of the recording head (6) in the paper conveyance direction and a paper pressing spur roller (27) that is pressed against and abuts against the paper ejection roller (26). Then, the rotation of the sub-scanning motor (28) composed of a stepping motor is controlled by the gears (29), (30), (31).
Also, the paper (20) stored in the paper feed unit (33) is transmitted to the platen (21) via the platen gear (32) and rotationally driven to drive the platen (21) and the paper feed roller (21). 22), (23) and the pinch roller (24), and then the recording head (6) and the guide plate (2).
5) and feed it to the paper (2) with the platen (21).
0) in the sub scanning direction while moving the platen gear (3
The paper (20) is sent out in the paper discharge direction (direction of arrow B in FIG. 2) by the paper discharge roller (26) and the paper pressing spur roller (27) which are rotated via the gear (34) meshing with 2).

In this recording apparatus having the above structure, the recording head (6) (carriage (5)) is moved and scanned in the main scanning direction while the paper (20) is conveyed in the sub scanning direction, and the recording head ( 6) Each head (6y), (6m),
A desired color image (including a black image) is recorded on the paper (20) by ejecting ink droplets of a desired color from the nozzles (8) of (6c) and (6b). Similarly, the back surface treatment liquid is discharged.

In this recording apparatus, the recording head (6) is provided on the right side of the main scanning area of the carriage (5).
The reliability maintaining / restoring mechanism (subsystem) (35) is provided, and when the print data is not transferred from the host side for a predetermined time, or at a predetermined time interval, the recording head (6) is provided. The reliability maintenance / recovery operation such as removing the dirt on the nozzle surface and the nozzle in (4) is performed.

Next, the outline of the control unit of this ink jet recording apparatus will be described with reference to FIG. This control unit includes a microcomputer (hereinafter referred to as “CPU”) (40) that controls the entire recording apparatus, and various fixed information such as color correction for image data and information necessary for image processing such as binarization. A ROM (41) storing information and / or various processing programs, a RAM (42) used as a working memory, a parallel input / output (PIO) port (43), an input buffer (44), and a character generator ( 45), a line feed counter (46), and a direct memory access controller (DMAC) (47)
A 1-line output buffer (48) and a parallel input / output (PIO) port (49) are provided.

Then, the control section is provided with a recording head (6).
Heads (6u), (6y), (6m), (6c),
A common (Com) driver (50) for applying a drive waveform to each energy generating means of (6b) and each head (6u), (6y), (6m), (6) of the recording head (6).
c), a driver (51) for giving a selection signal for selecting the energy generating means of (6b) according to the recording signal, and a motor driver (52) for driving and controlling the main scanning motor (15) and the sub scanning motor (28) respectively. ) And the like, and outputs a required signal to each unit, and an operation panel (operation panel) (53) is connected. A gate array (GA) may be used instead of the parallel input / output port (PIO) (49).

Here, various instructions and selection signals given from the operation panel (53) are input to the PIO (43), and various display signals and the like from the PIO (43) to the operation panel (53). Is output. Also, PIO
In (43), the image data from the host side, the sheet type data indicating the sheet type, and other data are input, and P
Various signals are output to the host side via the IO (43). Further, the PIO (43) has detection signals from a paper presence sensor that detects the start and end of the paper, signals from various sensors such as a home position sensor that detects the home position (reference position) of the carriage (5), and the like. Is entered.

The input buffer (44) is a PIO.
The print data from the host side received via (43) is temporarily stored. The character generator (45) converts print data into image data when the print data is received as code data. The line feed counter (46) counts the number of line feeds. The DMAC (47) is an input buffer (44)
A process such as reading the print data temporarily stored in the image data, converting it to image data by the character generator (45) and transferring print data for one line to the output buffer (48), if necessary, is performed. To do.

Further, the recording data accumulated in the output buffer (48) is read out at a required timing to be PIO.
It is sent as a print signal to (49), is given to the driver (51) from the PIO (49), and is sent to the recording head (6) as a drive signal (selection signal) from the driver (51). Further, a drive control signal is output to the motor driver (52) via the PIO (49) to move and scan the carriage (5) in the main scanning direction, and the platen (21).
Is rotated to convey the paper (20) by a predetermined amount.

Next, the operation of this ink jet recording apparatus will be described with reference to FIGS. 6 and 7. First, the inkjet recording method according to the present invention will be described with reference to FIG. 6. In the inkjet recording method according to the present invention, the back surface treatment liquid is printed in the vicinity of the back side of the recording image printing portion on the recording surface. There is. That is, the back surface treatment liquid is applied to the back side of the recording surface before, after, or at the same time as the image recording liquid is attached to the recording surface. Although the drawing shows the state in which the recording liquid and the back surface treatment liquid are in contact with each other, they do not necessarily have to come into contact with each other if the purpose is to reduce the back surface density (prevention of strike through). However, when the recording liquid and the backside treatment liquid are in contact with each other, a combination is preferable in which the coloring agent in the recording liquid and the treatment agent in the backside treatment liquid react to insolubilize the coloring agent. Further, it is preferable to print the front surface image after applying the back surface treatment liquid. Further, when the back surface processing liquid and the front surface recording liquid come into contact with each other, there is an effect that there is less slippage from the image on the front surface, the density is made uniform, and the graininess of the image is reduced. If this is utilized, it is possible to reduce the surface image density by applying the back surface treatment liquid without using the dark and light ink that is generally used in the printing of photographic images, and replace it with the light ink. In this case, the back surface treatment liquid is applied to the light image density portion of the image, and the back surface treatment liquid is not applied to the other portions. For this purpose only, it is not always necessary to add a polyvalent metal, a metal oxide, a cationic substance or the like to the back surface treatment liquid.

In the above-described apparatus, the recording surface and the back surface are not designed to be printed at the same time. Therefore, a paper reversing / feeding mechanism and a double-sided copying transport mechanism are provided to reverse the paper and use it as the recording liquid. The backside treatment liquid will be printed. In this case, the printing of the back side processing liquid is a printing of the pattern related to the recording liquid and the left and right mirror images. It should be noted that even if only one side of the recorded image is obtained, a copy without show-through can be obtained, but when it is desired to perform double-sided copying, the paper is inverted again, and the side on which the recorded image is not printed is used as the recording surface and the same processing is performed.

Since the above ink jet recording apparatus does not have a reversing mechanism, after the completion of printing on the surface, the printer driver displays a message prompting the operator to reverse and feed the sheet again, and the sheet is re-fed. The user waits until the paper is printed and enters the back side printing when the start of the back side printing is instructed. By providing the recording apparatus with a simple reverse sheet feeding mechanism, a double-sided copying conveyance mechanism used in a copying apparatus, etc., it is possible to automatically perform sheet re-feeding.

As described above, in this ink jet recording apparatus, since the back side processing liquid is printed by reversing or re-feeding after or before printing on the recording surface, the printing time becomes relatively long, and therefore, FIG. It is also possible to print two sets of recording heads on both sides of the sheet conveyance path, as shown in FIG. By doing so, it is possible to suppress an increase in printing time. In this case, in the case of single-sided copying, the head on the back side of the recording surface prints only the back surface treatment liquid.

On the other hand, in the case of double-sided copying, both sides serve as recording surfaces. If these are designated as recording surfaces A and B, the back surface treatment liquid on the recording surface A side is transferred to the position corresponding to the recording portion of recording surface B. The treatment liquid is applied, and the back surface treatment liquid on the recording surface B side is applied to the position corresponding to the recording portion of the recording surface A. According to this method, double-sided copying can be performed on both the back and front sides at the same time. When the positions of the recording portions of the recording surfaces A and B are aligned, the purpose of the treatment liquid is to prevent strike-through, that is, when the treatment liquid has a concealing effect for the strike-through, the treatment liquid prevents the surface image itself from being hidden. Therefore, the back surface treatment liquid is applied before the image recording liquid is applied. Alternatively, image processing is performed such that the back surface treatment liquid is not applied only to that portion.

In FIG. 7, the recording surfaces A and B are arranged to be printed at the same time. However, when the liquids are simultaneously adhered to both surfaces at the same position as described above, the drying is insufficient and bleeding or the like occurs. May be adversely affected. In order to prevent this, the heads may be arranged so as to be offset from each other so that they are not printed at the same time.

Usually, pretreatment for jetting from the recording surface side,
Alternatively, a post-treatment liquid head may be provided to apply the treatment liquid from both the back and front of the recording surface. The back surface treatment liquid may be applied by a so-called first coating method in which the back surface treatment liquid is not sprayed from a nozzle and is applied from a coating roller. If it is known to print on both sides, as shown in FIG.
First, when applying the colorant to the image area on the front surface, the treatment liquid is applied to the front surface side of the image area on the back surface, and then the paper is turned over so that the colorant is added to the image area on the back surface. Apply the treatment liquid to the back surface. According to this method, an image in which the treatment liquid is processed on both sides of the paper can be obtained by only reversing the paper once. When the treatment liquid has a function of preventing feathering, bleeding, etc., the treatment liquid may be applied to the colorant-applied portion from the same surface side. Also in these cases, the apparatus as shown in FIG. 7 may be used to print on both sides at once.

Next, various materials will be described. First, an ink containing a colorant that can be used in the present invention will be described. Regarding the colorant for the colored ink used in the present invention, general dyes and pigments can be used without particularly limiting the type, and acid dyes, direct dyes, reactive dyes, and basic dyes can be used. . Specific examples of dyes include
The following may be mentioned, but the present invention is not limited thereto.

Examples of the acid dyes and food dyes include the following. C. I. Acid Yellow 17,23,42,44,
79, 142, C.I. I. Acid Red 1,8,13,14,18,
26, 27, 35, 37, 42, 52, 82, 87, 8
9, 92, 97, 106, 111, 114, 115, 1
34, 186, 249, 254, 289, C.I. I. Acid Blue 9,29,45,92,24
9, C.I. I. Acid Black 1, 2, 7, 24, 26,
94, C.I. I. Food Yellow 3,4, C.I. I. Hood Red 7, 9, 14, C.I. I. Food black 1, 2,

The direct dyes include the following. C. I. Direct Yellow 1, 12, 24, 26,
33, 44, 50, 86, 120, 132, 142, 1
44, C.I. I. Direct Red 1, 4, 9, 13, 17,
20, 28, 31, 39, 80, 81, 83, 89, 2
25,227, C.I. I. Direct Orange 26, 29, 62, 10
2, C.I. I. Direct Blue 1, 2, 6, 15, 22,
25,71,76,79,86,87,90,98,1
63, 165, 199, 202, C.I. I. Direct Black 19,22,32,3
8, 51, 56, 71, 74, 75, 77, 154, 1
68, 171,

The basic dyes include the following. C. I. Basic Yellow 1,2,11,13,1
4,15,19,21,23,24,25,28,2
9, 32, 36, 40, 41, 45, 49, 51, 5
3, 63, 64, 65, 67, 70, 73, 77, 8
7, 91, C.I. I. Basic Red 2,12,13,14,1
5,18,22,23,24,27,29,35,3
6,38,39,46,49,51,52,54,5
9,68,69,70,73,78,82,102,1
04, 109, 112, C.I. I. Basic Blue 1,3,5,7,9,2
1, 22, 26, 35, 41, 45, 47, 54, 6
2,65,66,67,69,75,77,78,8
9, 92, 93, 105, 117, 120, 122, 1
24, 129, 137, 141, 147, 155, C.I. I. Basic Black 2,8,

Examples of the reactive dye include the following. C. I. Reactive Black 3,4,7,11,1
2, 17, C.I. I. Reactive Yellow 1, 5, 11, 13,
14, 20, 21, 22, 25, 40, 47, 51, 5
5,65,67, C.I. I. Reactive Red 1,14,17,25,
26, 32, 37, 44, 46, 55, 60, 66, 7
4, 79, 96, 97, 141, C.I. I. Reactive blue 1,2,7,14,1
5,23,32,35,38,41,63,80,9
5, Among them, acid dyes and direct dyes are particularly preferably used.

The pigment is not particularly limited, but a conventional ink jet pigment ink is used. A self-dispersible pigment having a hydrophilic group on the surface of the pigment, an ink in which the pigment is dispersed by a water-soluble resin or a surfactant, or a polymer emulsion type in which polymer fine particles contain a water-insoluble or sparingly soluble coloring material. An inkjet pigment ink or a microcapsule type pigment ink in which a pigment is coated with a resin having a hydrophilic group can be used.

A liquid wetting agent is added to the ink containing the colorant. The liquid humectant is a humectant which is liquid at room temperature, and in particular, a water-soluble organic solvent having a high boiling point and low volatility (for example, a water-soluble organic solvent having a boiling point of 200 ° C. or higher) can be used. Examples of the water-soluble organic solvent include polyhydric alcohols, particularly divalent to pentavalent alcohols having 2 to 10 carbon atoms; nitrogen-containing hydrocarbon solvents such as formamides, imidazolidinones, pyrrolidones, and the like. Alternatively, amines; sulfur-containing hydrocarbon solvents can be mentioned, and those solvents can be used alone or in combination.

The ink composition of the present invention uses water as a liquid medium. To make the ink have desired physical properties, to prevent the ink from drying, and to improve the dissolution stability, etc. For the purpose of, for example, the following water-soluble organic solvents are used. A plurality of these water-soluble organic solvents may be mixed and used.

Specific examples of preferable water-soluble high-boiling point low-volatile organic solvent include the following. Ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, tetraethylene glycol, hexylene glycol, polyethylene glycol, polypropylene glycol, 1,5-pentanediol, 1,6-hexanediol, glycerol, 1,
Polyhydric alcohols such as 2,6-hexanetriol, 1,2,4-butanetriol, 1,2,3-butanetriol and petriol; ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol Polyhydric alcohol alkyl ethers such as monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether and propylene glycol monoethyl ether; polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether; 2- Pyrrolidone, N-methyl-2-pyrrolidone, N
-Hydroxyethyl-2-pyrrolidone, 1,3-dimethylimidazolidinone, ε-caprolactam, γ-butyrolactone and other nitrogen-containing heterocyclic compounds; formamide, N
-Amids such as methylformamide and N, N-dimethylformamide; amines such as monoethanolamine, diethanolamine, triethanolamine, monoethylamine, diethylamine and triethylamine; sulfur-containing compounds such as dimethylsulfoxide, sulfolane and thiodiethanol; Examples include propylene carbonate and ethylene carbonate.

Among these organic solvents, especially diethylene glycol, thiodiethanol, polyethylene glycols 200 to 600, triethylene glycol, glycerol, 1,2,6-hexanetriol, 1,2,4.
-Butanetriol, petriol, 1,5-pentanediol, 2-pyrrolidone, N-methyl-2-pyrrolidone and 1,3-butanediol are preferred. These have excellent effects on solubility and prevention of defective ejection characteristics due to water evaporation.

The other wetting agent preferably contains sugar. Examples of sugars include monosaccharides, disaccharides,
Examples include oligosaccharides (including trisaccharides and tetrasaccharides) and polysaccharides, preferably glucose, mannose, fructose, ribose, xylose, arabinose, galactose, maltose, cellobiose, lactose, sucrose, trehalose, maltotriose and the like. To be Here, the polysaccharide means a sugar in a broad sense, and is meant to include substances widely existing in the natural world such as α-cyclodextrin and cellulose.

The derivatives of these sugars include reducing sugars of the above-mentioned sugars (for example, sugar alcohol (general formula H
It is represented by OCH ₂ (CHOH) nCH ₂ OH (where n represents an integer of 2 to 5). ), Oxidized sugars (eg, aldonic acid, uronic acid, etc.), amino acids, thioacids and the like. Particularly, sugar alcohols are preferable, and specific examples thereof include maltitol, sorbitol and the like. The content of these saccharides is appropriately 0.1 to 40% by weight, preferably 0.5 to 30% by weight of the ink composition.

Further, the colorant-containing ink may contain various activators for lowering the surface tension in order to improve the penetrability into paper. The anionic or nonionic surfactant is not particularly limited, but as the anionic surfactant, for example, polyoxyethylene alkyl ether acetate, dodecylbenzene sulfonate, lauryl acid salt,
Examples thereof include salts of polyoxyethylene alkyl ether sulfate.

Examples of the nonionic surfactant include, for example,
Examples thereof include polyoxyethylene alkyl ether, polyoxyethylene alkyl ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene alkylphenyl ether, polyoxyethylene alkylamine, and polyoxyethylene alkylamide.

As the acetylene glycol-based surfactant, 2,4,7,9-tetramethyl-5-decyne-4,
7-diol, 3,6-dimethyl-4-octyne-3,
6-diol, 3,5-dimethyl-1-hexyne-3-
Acetylene glycol type such as oar (for example, Surfynol 104, 82, 4 of Air Products (USA))
65, 485 or TG) can be used, but Surfynol 465, 104 and TG show particularly good print quality. The surfactants may be used alone or in combination of two or more.

The polyol or glycol ether having from 8 to 11 carbon atoms used in the present invention is a partially water-soluble polyol and / or a water-soluble polyol having a solubility of 0.1 to less than 4.5% by weight in water at 25 ° C. Alternatively, glycol ether is used in an amount of 0.1 to 1 with respect to the total weight of the recording ink.
It was found that the addition of 0.0% by weight improves the wettability of the ink to the thermal element, and discharge stability and frequency stability can be obtained even with a small amount of addition. (1) 2-Ethyl-1,3-hexanediol Solubility: 4.2% (20 ° C.), (2) 2,2,4-Trimethyl-1,3-pentanediol Solubility: 2.0% (2
5 ° C),

Penetrants having a solubility between 0.1 and less than 4.5% by weight in water at 25 ° C. have the advantage that they have a very high permeability instead of a low solubility. Therefore,
The combination of a penetrant having a solubility between 0.1 and less than 4.5% by weight in water at 25 ° C. with other solvents or with other surfactants produces a very highly penetrative ink. It becomes possible.

The ink composition for ink jet recording which can be used in the present invention contains each of the above-mentioned components. In addition, various conventionally known additives such as a water-soluble organic solvent other than the liquid wetting agent and various If necessary, a dispersant, a viscosity modifier, and / or a fluorescent brightening agent may be contained.
Examples of the viscosity modifier include water-soluble natural or synthetic polymer compounds such as celluloses, polyvinylpyrrolidone, polyvinyl alcohol, and water-soluble resins. Further, a buffer solution as a pH adjusting agent, an antifungal agent and the like may be contained.

For example, as antiseptic / antifungal agents, sodium dehydroacetate, sodium sorbate, 2-pyridinethiol-1-oxide sodium, sodium benzoate, pentachlorophenol sodium and the like can be used in the present invention.

As the pH adjuster, any substance can be used as long as it can adjust the pH to 7 or more without adversely affecting the ink to be prepared. Examples thereof include amines such as diethanolamine and triethanolamine, hydroxides of alkali metal elements such as lithium hydroxide, sodium hydroxide and potassium hydroxide, ammonium hydroxide, quaternary ammonium hydroxide and quaternary phosphonium. Examples thereof include hydroxides, carbonates of alkali metals such as lithium carbonate, sodium carbonate and potassium carbonate.

Examples of the chelating agent include sodium ethylenediaminetetraacetate, sodium nitrilotriacetate, sodium hydroxyethylethylenediaminetriacetate, sodium diethylenetriaminepentaacetate and sodium uramildiacetate.

Examples of the rust preventive agent include acidic sulfite,
There are sodium thiosulfate, ammonium thiodiglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, dicyclohexylammonium nitrite and the like. A water-soluble ultraviolet absorber, a water-soluble infrared absorber or the like can be added depending on the purpose.

Further, a specific resistance adjusting agent, for example, an inorganic salt,
For example, alkali metal halides or ammonium halides (eg lithium chloride, ammonium chloride,
A recording liquid used in an ink jet recording method of a type in which the recording liquid is charged can be prepared by containing (sodium chloride) or the like.

By adjusting the compounding ratio of the above components,
Applicable to the inkjet recording method of the type that discharges the recording liquid by the action of thermal energy by adjusting the thermal property values (evaporation heat, boiling point, melting point, specific heat, thermal expansion coefficient, and / or thermal conductivity, etc.) It is also possible to prepare an ink composition containing

The viscosity of the ink composition of the present invention is preferably 20 mPa · s or less, more preferably 15 mP · s.
It is possible to ensure stable ejection from the head and stable ink supply to the head by adjusting to a · s or less.

The ink composition for ink-jet recording of the present invention is prepared by appropriately mixing and mixing (or dispersing) the above-mentioned respective components in an arbitrary order, and then removing impurities and the like by filtration. be able to. Further, a colorant is appropriately selected, and if necessary, other compounding ingredients are appropriately selected in combination with the selected colorant, and the yellow ink composition, the magenta ink composition according to the present invention for color inkjet recording, A cyan ink composition, a black ink composition, a blue ink composition, a green ink composition, or a red ink composition can be prepared.

Next, the processing agent in the processing liquid applied from the back surface of the recording surface, which is the main element of the present invention, will be described. First, the inorganic oxide dispersion type treating agent will be described. The function of the inorganic oxide dispersion-based treatment agent mainly contributes to strike-through prevention and image clarity. In the case of a cationic type, it also contributes to improving the water resistance of the anionic colorant. Further, the one having a large particle size prevents the surface image from being seen through. The material is fine particles of cationic or anionic titanium oxide, silicon oxide, zirconium oxide, etc.
It is less than μm. Commercially available alumina and silica colloidal sols can also be used.

To these, a wetting agent similar to the above-described colored ink may be added to prevent evaporation and drying. Further, it can be used without any particular addition. As various other additives (penetrating agent, surfactant, antiseptic agent, etc.), those described in the colored ink can be used. These may be used as a mixture with various dispersants and water-soluble resins.

The weight of the metal oxide is preferably 0.5 to 30% by weight. If the amount is too small, there is no effect, and if the amount is too large, the injection stability is poor.

The pH is adjusted to 3-10. Cationic colloids are used relatively acidic, and anionic ones are used relatively basic.

Even when the recording liquid does not come into contact with the inorganic oxide-containing treatment liquid, there is some strike-through prevention effect (shielding effect), but when the back surface treatment liquid containing these inorganic oxides comes into contact with the recording liquid, It also contributes to image clarity and fixability.

Next, a treatment liquid containing a cationic group will be described as a back surface treatment liquid agent. The treating agent having a cationic group is mainly used as a fixing function for dyes and pigments.
This function is exerted only when the treatment liquid applied from the back side comes into contact with the colored ink on the recording side. In addition,
The compound having a cationic group may be in a state of forming a salt with a counter anion such as chloride ion in a solution, or may be in a so-called free state without a counter anion.

[0062]

[Chemical 1] Although these change with pH adjustment, the free state has high pH and the fixing property to the anionic dye is relatively weak, but it can be used.

Typical examples of the organic cationic compound include (A) primary, secondary, tertiary and quaternary nitrogen (amine or ammonium) and phosphorus (phosphonium).
There is a high molecular weight compound having a in the molecular chain or as a pendant chain, and (B) a low molecular weight cationic organic compound.
Specific examples of (A) include the following.

[0064]

[Chemical 2] (M is an integer of 0 to 3, R ¹ , R ² and R ³ represent hydrogen or a lower alkyl group or a lower alkanol group.) These may be salts formed with a counter anion such as chlorine or may be in a free state. Good. These high molecular weight cationic compounds can be used as a compound with any acid such as hydrochloride, acetate, nitrate and sulfate.

The trade names of the above polymeric cationic organic compounds are Sunfix 414, 414-C55
5,555US, 70, PRO-100 (above, Sanyo Kasei Co., Ltd.), Protex 200, Fix K, H, S
K, MCL, FM (above, Satoda Processing Co., Ltd.), Morin Fix Conc 3M (Morin Chemical Co., Ltd.), Amigen (Daiichi Yakuhin Kogyo Co., Ltd.), Epomin P100 (Nippon Shokubai Co., Ltd.), Fix Oil R737, E50 ( As mentioned above, manufactured by Meisei Chemical Co., Ltd., Eofix RS (manufactured by Nichika Chemical Co., Ltd.), polyamine sulfone, polyallylamine (manufactured by Nitto Boseki Co., Ltd.),
Polyfix 601 (manufactured by Showa High Polymer Co., Ltd.), Nikafix D100 (manufactured by Nippon Carbide Co.), Rebogen B (manufactured by Bayer Co., Ltd.), Kaimen 557 (manufactured by Dick Hercules Co., Ltd.) and the like can be mentioned. If the molecular weight of these high molecular weight cationic compounds is too large, the solubility will be poor and the viscosity of the solution will be too high. Therefore, in the present invention, those having a molecular weight of 100,000 or less are preferably used. Particularly preferred is a compound having a molecular weight of 20,000 or less containing 5 to 200 cationic groups in one molecule.

Specific examples of the above (B) include the following. Ethylenediamine, hexamethylenetetramine, piperazine, 1- (2'-aminoethyl) piperidine, 1- (2'-aminoethyl) aziridine, 1-
(2'-aminoethyl) pyrrolidine, 1- (2'-aminoethyl) hexamethyleneimine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, N, N'-bis- (3
-Aminopropyl) putrescine, N- (3-aminopropyl) putrescine, 1,4-diazacycloheptane, 1,5-diazacyclooctane, 1,4,11,1
4-tetraazacycloeicosane, 1,10-diazacyclooctadecane, 1,2-diaminopropan-3-ol, 1-amino-2,2-bis (aminomethyl) propan-1-ol, 1,3 -Diaminopropan-2-ol, N- (2-oxypropyl) ethylenediamine,
Heptaethyleneoctamine, nonaethylenedecamine,
1,3-bis (2'-aminoethylamino) propane,
Triethylene-bis (trimethylene) hexamine, 1,
2-bis [3 '-(2 "-aminoethylamino) propylamino] ethane, bis (3-aminoethyl) amine,
Aliphatic or alicyclic polyvalent amines such as 1,3-bis (3′-aminopropylamino) propane and sym-homospermidine, and among them, having 3 or more nitrogen atoms in one molecule The compound is particularly preferably used in the present invention. This is because a compound having only two or less nitrogen atoms does not easily react with the dye to form an insoluble bond. Further, phenylenediamine, triaminobenzene, tetraaminobenzene, pentaaminobenzene, hexaaminobenzene, 2,6- or 2,5-diamino-
Aromatic polyvalent amino acids such as p-benzoquinonediimine and 2,3,7,8-tetraaminophenazine may be used.

For the synthesis method of these compounds, see BARTO.
N, OLLIS “COMPREHENSIVE ORGANIC CHEMISTRY” Peryamon
Press (1979) and the like. The content of such an organic cationic compound in a colorless or pale-colored liquid is not particularly limited.

The solution containing the organic cationic compound is required to be dried quickly after it is applied to the recording medium, particularly when printing is performed at high speed. In addition, the printed ink is also required to penetrate quickly. In order to satisfy this requirement, it is desirable to add a compound for enhancing the permeability of the back surface treatment liquid (organic cationic compound-containing solution) itself and / or the ink to the recording medium to the organic cationic compound-containing solution.

On the other hand, one or more groups selected from the group consisting of an alkyl group having 4 or more carbon atoms, an alkenyl group and an aryl group as described in JP-A-1-69381 are incorporated into the molecule. Both the quaternary ammonium salt or amine salt and the compound having a cationic group can be used as the treatment liquid of the present invention. The penetrant used for the colored ink can be used. In addition, the wetting agent used in the colored ink and other various additives can be used.

Next, the treatment liquid containing a polyvalent metal salt will be described. As this, those described in JP-A-63-299970 can be used. The treatment liquid containing a polyvalent metal salt provides image clarity, strike-through prevention, and feathering prevention.
It also has a fixing function. Examples of cations in this polyvalent metal salt include aluminum Al (III) and calcium C
a (II), magnesium Mg (II), copper Cu (II), iron Fe (II) and Fe (III), zinc Zn (II), tin S
n (II) and Sn (IV), strontium Sr (II),
Nickel Ni (II), Cobalt Co (II), Barium B
a (II), lead Pb (II), zirconium Zr (IV), titanium Ti (IV), antimony Sb (III), bismuth B
i (III), tantalum Ta (V), arsenic As (III), cerium Ce (III), lanthanum La (III), yttrium Y (III), mercury Hg (II), beryllium Be (II).
Among others, considering color tone (nearly colorless), cost, safety, etc., Al (III), Ca (I
I), Mg (II), Zn (II), Fe (II), Fe (II
I), Sn (II) and Sn (IV) are particularly preferred. In addition to these polyvalent metal ions, alkali metals, ammonium,
It is also possible to use double salts containing monovalent cations such as hydrogen.

Examples of anions include fluorine F and chlorine C
1, anion of a halogen element such as bromine Br, iodine I;
Nitrate ion NO ₃ ⁻ , Sulfate ion SO ₄ ²⁻ ; Anion of organic carboxylic acid such as formic acid, acetic acid, lactic acid, malonic acid, oxalic acid, maleic acid, benzoic acid; benzenesulfonic acid, naphtholsulfonic acid, alkylbenzenesulfonic acid, etc. Anion of organic sulfonic acid; thiocyan ion SCN−, thiosulfate ion S ₂ O ₃ ²⁻ , phosphate ion PO ₄ ³⁻ , nitrite ion NO ₂ ^{− and the} like.

In order to deposit the polyvalent metal salt-containing solution on the recording medium by the ink jet method, the polyvalent metal salt may be added to water and / or an organic solvent (methanol, ethanol) in consideration of nozzle clogging, storability and the like. Alcohols such as; ketones such as acetone, methyl ethyl ketone, etc.), which are well dissolved, are advantageously used.

The solubility of each solution is greatly affected by the anion, and Br ⁻ , I ⁻ , NO ₃ ⁻ and organic acid ions are particularly preferable among the above anions because they are excellent in solubility.

The polyvalent metal-containing backside treatment liquid must be quickly absorbed in the medium, and therefore it is preferable to add a penetrant. In addition to the above, as a material that can be added to the polyvalent metal salt-containing solution, a material that has been conventionally added to an ink used in a general inkjet recording method can be similarly used. Examples thereof include viscosity modifiers, antiseptics (including antiseptic and antifungal agents), pH adjusters, and ultraviolet absorbers.

Next, a white or pale yellow resin is shown as an agent for the back surface treatment liquid. The treatment liquid added with this contributes to the reduction of graininess. In order to improve the shielding effect, it is preferable to use it in combination with a polyvalent metal salt or the like. Mainly, celluloses, carboxymethyl celluloses, polyacrylic acid salts, and styrene-acrylic acid copolymers are preferable. It should be noted that various additives usually used in colored inks can be used in combination.

[0076]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto. In addition,
The amount (%) of each component described in the examples is based on weight. A backside treatment liquid having the following formulation was prepared. <Back surface treatment liquid> Magnesium nitrate hexahydrate 15% Glycerin 5% 1,3-Butanediol 15% 2-Ethyl-1,3-hexanediol 2% Polyoxyalkylene derivative Dispanol TOC (Nippon Yushi-Se) 1% Proxel LV (preservative) 0.2% Ion-exchanged water Remaining amount The pH was adjusted to about 8 with lithium hydroxide.

On the other hand, a colored ink having the following formulation was prepared. Reference Example 1 (Preparation of Phthalocyanine Pigment-Containing Polymer Fine Particle Dispersion) An adjustment example 3 of JP 2001-139849 A was additionally tested to obtain a blue polymer fine particle dispersion. The average particle diameter (D50%) of the polymer particles measured by Microtrac UPA was 93 nm.

<Reference Example 2> (Preparation of dimethylquinacridone pigment-containing polymer fine particle dispersion) A red-purple polymer fine particle dispersion was prepared in the same manner as in Reference Example 1 except that the phthalocyanine pigment of Reference Example 1 was changed to Pigment Red 122. Obtained. Average particle size of polymer particles measured by Microtrac UPA (D50
%) Was 127 nm.

<Reference Example 3> (Preparation of polymer fine particle dispersion containing monoazo yellow pigment)
The phthalocyanine pigment of Reference Example 1 was used as Pigment Yellow 7
A yellow polymer particle dispersion was obtained in the same manner as in Reference Example 1 except that the number was changed to 4. The average particle size (D50%) of the polymer particles measured by Microtrac UPA is 76n.
It was m.

Reference Example 4 (Preparation of carbon black-containing polymer particle dispersion)
A black polymer fine particle dispersion was obtained in the same manner as in Reference Example 1, except that the phthalocyanine pigment of Reference Example 1 was changed to carbon black (FW100 manufactured by Degussa). Average particle size of polymer particles measured by Microtrac UPA (D
50%) was 104 nm.

Reference Example 5 (Diazo Compound Treated Carbon Black Dispersion 1) The surface area is 230 m ² / g and the DBP oil absorption is 70 ml / 10.
0 g of carbon black 100 g and p-amino-N-
34 g of benzoic acid was mixed and dispersed in 750 g of water, 16 g of nitric acid was added dropwise to this, and the mixture was stirred at 70 ° C. 5 minutes later, 50g
A solution of 11 g of sodium nitrite in water was added, and the mixture was further stirred for 1 hour. The obtained slurry was diluted 10 times, centrifuged to remove coarse particles, and the pH was adjusted to 8 to 9 with diethanolamine, and desalted and concentrated with an ultrafiltration membrane to obtain a carbon black dispersion having a pigment concentration of 15%. did. This was made into a carbon black dispersion liquid 1 using a polypropylene 0.5 μm filter. Average particle size (D50%) measured by Microtrac UPA is 99 nm
Met.

(Cyan pigment ink) An ink composition having the following formulation was prepared, and lithium hydroxide 1 was added to adjust the pH to 9.
It was adjusted with a 0% aqueous solution. After that, the average pore diameter is 0.8 μm
An ink composition was obtained by performing filtration with the membrane filter of No. 2. Phthalocyanine pigment-containing polymer fine particles of Reference Example 1 8.0 wt% (as solid content) Triethylene glycol 22.5 wt% Glycerol 7.5 wt% 2-Pyrrolidone 5.0 wt% Polyoxyalkylene derivative Dispanol TOC (manufactured by NOF Corporation) 1 0.0 wt% 2-Ethyl-1,3-hexanediol 2.0 wt% Proxel LV (preservative) 0.2 wt% Ion-exchanged water Remaining amount

(Magenta Pigment Ink) An ink composition was prepared in the same manner as the cyan ink except that the following composition was used, and the pH was adjusted to 9 with sodium hydroxide. Polymer particles containing dimethylquinacridone pigment in Reference Example 2 8.0 wt% (as solid content) Propylene glycol 30.0 wt% Glycerol 10.0 wt% N-methyl-2-pyrrolidone 2.0 wt% Polyoxyalkylene derivative Dispanol TOC (Japan Oil and fat) 1.0 wt% 2,2,4-trimethyl-1,3-pentanediol 2.0 wt% Proxel LV (preservative) 0.2 wt% Deionized water remaining amount

(Yellow Pigment Ink) An ink composition was prepared in the same manner as the cyan ink except that the following composition was used, and the pH was adjusted to 9 with lithium hydroxide. Monoazo yellow pigment-containing polymer fine particles of Reference Example 3 8.0 wt% (as solid content) 1,3-butanediol 22.5 wt% glycerol 7.5 wt% 2-pyrrolidone 5.0 wt% Polyoxyalkylene derivative dispanol TOC (Japan Oil and fat) 1.0 wt% 2,2,4-trimethyl-1,3-pentanediol 2.0 wt% Proxel LV (preservative) 0.2 wt% Deionized water remaining amount

(Black Pigment Ink (1)) An ink composition was prepared in the same manner as the cyan ink except that the following composition was used, and the pH was adjusted to 9 with sodium hydroxide. Carbon black-containing polymer fine particles of Reference Example 4 8.0 wt% (as solid content) Dipropylene glycol 20.0 wt% Glycerol 10.0 wt% N-hydroxyethyl-2-pyrrolidone 5.0 wt% Polyoxyalkylene derivative dispanol TOC ( Nippon Oil & Fats) 1.0 wt% 2-Ethyl-1,3-hexanediol 2.0 wt% Proxel LV (preservative) 0.2 wt% Ion-exchanged water Remaining amount

(Black Pigment Ink (2)) An ink composition was prepared in the same manner as in Black Pigment Ink (1) except that the following black ink was used, and the pH was adjusted to 9 with lithium hydroxide. Carbon black dispersion liquid treated with the diazo compound of Reference Example 1 8.0 wt% (as solid content) 1,4-butanediol 22.5 wt% Glycerol 7.5 wt% N-methyl-2-pyrrolidone 2.0 wt% Polyoxy Alkylene derivative Dispanol TOC (manufactured by NOF CORPORATION) 1.0 wt% 2,2,4-trimethyl-1,3-pentanediol 2.0 wt% Emulsion 3.0 wt% Proxel LV (preservative) 0.2 wt% Ion-exchanged water Remaining amount

[0087] (Magenta dye ink)     C. I. Acid Red 52 2%     Diethylene glycol 12%     Glycerin 4%     2-ethyl-1,3-hexanediol 2%     Proxel LV (preservative) 0.2 wt%     Water level

Ricoh inkjet printer IPS
Solids and characters were printed while adjusting the drive voltage of the head of iO Jet300.

Example 1 Backside treatment liquid ... Black pigment ink on the surface (2) Inkjet printer IPSiO Jet manufactured by Ricoh
The drive voltage of 300 heads was changed and solid and characters were printed. The paper is PB paper (Canon Sales Inc.). First, the treatment liquid was printed on the back surface. The applied piezo voltage is 240V. The print is a solid print of 600 dpi one-way print. After the treatment liquid was printed and discharged, the paper was inverted and fed again to the machine to print the black pigment ink (2) on the surface. For comparison, it was compared with the case where the treatment liquid was not printed on the back surface. As a result, the back surface image density was clearly lower when the treatment liquid was printed on the back surface than when the treatment liquid was not printed. The results of measurement with a reflective color spectrophotometric densitometer (manufactured by X-Rite) are shown below. Black density of back surface where treatment liquid was applied to back surface: 0.17 Black density of back surface where treatment liquid was not applied to back surface: 0.20 Black image density of front surface: Although the difference was small, it was clearly observed by visual observation that the back surface treatment liquid-treated portion had a lower back surface concentration. That is, in the case of double-sided copying, the degree of recognizing the image on the opposite side from the back side was reduced. The reduction effect of strike-through is shown in FIG. On the contrary, first, the black pigment ink (2) was printed on the front surface, then the paper was turned over and the treatment liquid was printed on the back surface. In this case as well, the strikethrough was smaller in the processing liquid printing section. However, the contribution of the reduction in the back surface density by visual observation was smaller than that in the case where the front surface black image was printed after first printing the treatment liquid on the back surface as described above.

Example 2 Backside treatment liquid ... Magenta pigment ink In the same manner as in Example 1, printing was performed in the order of backside treatment liquid treatment → paper reversal → front surface magenta pigment ink printing. As a result, the measurement results with the densitometer are subtle and almost no difference is observed. Magenta concentration at the place where the treatment liquid is applied to the back surface: 0.19 Magenta concentration at the place where the treatment liquid is not applied to the back surface: 0.1
9 Magenta image density on the front surface: 0.87 As described above, it is difficult to judge the difference in the back surface density measurement results, but it was clearly found by visual inspection and photographs that the strikethrough was reduced by the treatment liquid (see FIG. 10). This is probably because the density value in X-Rite is a macroscopic physical property value. Therefore, in terms of image quality, the strikethrough was small in the portion treated with the backside treatment liquid, and the backside image quality was good with less unpleasant strikethrough when copying on both sides. On the contrary, surface magenta printing →
In the order of paper reversal → rear surface treatment liquid treatment, the strike-through was less in the treatment liquid treatment portion, but the effect was smaller than that in the above-mentioned order.

Example 3 The same experiment as in Example 2 was conducted on the cyan pigment ink. As a result, it was confirmed that strike through was small when the back surface treatment liquid was treated.

Example 4 The same experiment as in Example 2 was conducted on the yellow pigment ink. As a result, it was confirmed that strike through was small when the back surface treatment liquid was treated.

Example 5 The same experiment as in Example 2 was conducted on the black pigment ink (1). As a result, it was confirmed that strike through was small when the back surface treatment liquid was treated.

Example 6 The same experiment as in Example 2 was conducted on the magenta dye ink. As a result, compared to the case where the backside treatment liquid treatment was not performed, the portion where the backside treatment liquid treatment was performed had some (smaller number) magenta bleeding, but it was visually confirmed that the backside concentration was low overall. I was able to confirm it. In terms of visual image quality, it is sufficiently effective in reducing strike-through. Further, comparing the images on the front surface, it was found that the back surface treatment liquid applying portion had less white spots than the other areas, and the graininess due to this was reduced (see FIG. 11).

A backside treatment liquid having the following formulation was prepared.     Inorganic oxide pigment: Fine particle silica sol       (Cationic colloidal silica, solid content 18%) 50 wt%     Water-soluble organic solvent: Glycerin 5 wt%                   : Propylene glycol 15 wt%     Penetrant: Polyoxyalkylene derivative Dispanol TOC 0.5 wt%     Water level

A backside treatment liquid having the following formulation was prepared. Polyallylamine hydrochloride 5 wt% Glycerin 5 wt% 1,3-Butanediol 15 wt% Water The residual pH was adjusted to 8 with an aqueous lithium hydroxide solution.

A backside treatment liquid having the following formulation was prepared. Polyacrylic acid resin 0.5% Glycerin 5% 1,3-Butanediol 15% Deionized water remaining

Example 7 The same experiment as in Example 2 was conducted using the treatment liquid and the black pigment ink (2). As a result, the processing liquid processing unit causes image graininess,
The water resistance was good.

Example 8 Treatment Liquid and Dye Magenta Ink and Pigment Black Ink (2)
Then, the same experiment as in Example 2 was performed. As a result, it was confirmed that the back surface treatment liquid processing section had less show-through. In addition, the front surface image became uniform with less graininess due to the back surface treatment liquid (see FIG. 12). Furthermore, since the treatment liquid is a cationic compound, it has the effect of coming into contact with the anionic colorant within the paper surface and improving its fixing property.

Example 9 The same experiment as in Example 2 was conducted using the treatment liquid and the dye magenta ink. As a result, the back surface treatment liquid treatment section was less likely to pass through, and the uniformity of the solid portion was improved.

[0101]

As is clear from the above detailed and specific description, lining the treatment liquid lowers the back surface concentration,
In some cases, it contributes to the improvement of fixability, and high-quality good fixability in which show-through is difficult to recognize enables double-sided copying. Further, there is an effect of reducing the graininess of the image.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration diagram of an inkjet recording apparatus of the present invention.

FIG. 2 is another diagram showing a schematic configuration diagram of the inkjet recording apparatus of the present invention.

FIG. 3 is a diagram showing a recording head portion.

FIG. 4 is an enlarged view of each recording head.

FIG. 5 is a diagram illustrating an outline of a control unit of the inkjet recording apparatus of the present invention.

FIG. 6 is a diagram illustrating an inkjet recording method of the present invention.

FIG. 7 is another diagram showing a recording head portion.

FIG. 8 is a diagram showing a method of printing on both sides of a back surface treatment liquid.

FIG. 9 is a diagram showing an example in which strike-through is reduced by a treatment liquid.

FIG. 10 is a diagram showing an example in which strike-through is reduced by a treatment liquid.

FIG. 11 is a diagram showing an example in which the graininess of a surface image is improved.

FIG. 12 is a diagram showing a strike-through reduction effect when the treatment liquid is an amine.

[Explanation of symbols]

1 side plate 2 side plate 3 guide rod 4 guide plate 5 carriage 6 recording head U back surface treatment liquid C cyan ink M magenta ink Y yellow ink K black ink 6u back surface treatment liquid ejection head 6c cyan ink ejection head 6m magenta ink ejection head 6y yellow ink Ejection head 6b Black ink ejection head 7 Ink tank (ink cartridge) 8 Recording nozzle 10 Liquid chamber 11 Liquid chamber forming member 12 Nozzle forming member 13 Ink drop 15 Main scanning motor 16 Drive pulley 17 Driven pulley 18 Timing belt 20 Paper 21 Platen roller 22 Paper Feed Roller 23 Paper Feed Roller 24 Pinch Roller 25 Guide Plate 26 Paper Ejection Roller 27 Paper Pressing Spur Roller 28 Sub-scanning Motor 29 Gear 30 Gear 31 Gear 32 Gear Platen Gear 33 Paper Feed Unit 34 Gear 35 Signal Dependability maintenance recovery mechanism (subsystem) 40 CPU 41 ROM 42 RAM 43 Parallel input / output (PIO) port 44 Input buffer 45 Character generator 46 Line feed counter 47 Direct memory access controller (DMA)
C) 48 1 line output buffer 49 Parallel input / output (PIO) port, gate array (GA) 50 Common (Com) driver 51 Driver 52 Motor driver 53 Operation panel (Operation panel)

Claims (12)

[Claims] 1. In an inkjet recording method for recording an image by ejecting ink droplets onto a recording medium, before or after printing on a recording surface, or at the same time, the whole or a part of the recording section is in the vicinity of the recording section. An ink jet recording method, wherein a treatment agent is applied from the back side of the. 2. The ink jet recording method according to claim 1, wherein an image is printed using both sides of the recording medium as recording surfaces. 3. The ink jet recording method according to claim 1, wherein the recording heads are provided on both sides of the recording medium conveyance path with the recording head interposed therebetween. 4. The ink jet recording method according to claim 1, wherein the treatment agent contains a material that reduces the degree to which the recorded image is recognized from the back surface side. 5. The processing agent has a function of reducing graininess of a recorded image.
4. The inkjet recording method according to any one of 3 to 3. 6. When printing an image on both sides of a recording medium, when a front side is printed, a processing agent is previously applied to a portion corresponding to an image portion printed on the back side, and the back side is printed. 6. The inkjet recording method according to claim 1, wherein a treatment agent is applied to a portion corresponding to an image area on the surface. 7. A method of applying a coloring agent after applying a treatment agent to a front surface image portion at the time of surface printing, and applying a same treatment agent to a back surface image portion after applying a same treatment agent at the time of back surface printing. The inkjet recording method according to any one of claims 1 to 5. 8. The ink jet recording method according to claim 1, wherein the treating agent contains at least a polyvalent metal salt. 9. The ink jet recording method according to claim 1, wherein the treating agent contains at least a cationic compound. 10. The ink jet recording method according to claim 1, wherein the treatment agent contains at least an inorganic oxide. 11. The ink jet recording method according to claim 1, wherein the treatment agent contains at least a white or light yellow resin. 12. An inkjet printer device, wherein recording is performed by the recording method according to any one of claims 1 to 7.