JP2008229965A - Inkjet device, printing method using the same, actuating program and ink - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording device which effectively avoids the occurrence of beading and white patches and forms high-resolution images at high speeds. <P>SOLUTION: The linear inkjet recording device or a serial inkjet recording device has a means to control resolution in a printing paper feeding direction in accordance with the ink absorbency of the printing paper, convert and print image data in accordance with the resolution in the printing paper feeding direction and the resolution in a main scanning direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an inkjet recording apparatus, a printing method using the same, a program for causing a computer to execute the printing method, and ink to be applied.

Conventionally, inkjet recording devices are capable of high-speed recording, can be printed on so-called plain paper without special fixing processing, and recording noise corresponding to printers and various office equipment is extremely low. It is known to be excellent as a means of use.
In such an ink jet apparatus, ink droplets are ejected according to desired image information using an ink jet head in which nozzles communicating with a predetermined ink liquid chamber are formed, and are adhered to a recording medium such as paper or film. To form an image.

As such an ink jet printer, a serial type and a line type are known.
The serial type ink jet recording apparatus forms an image while scanning the ink jet head in the width direction of the printing paper (main scanning), and after one or more scans are completed, the paper is conveyed to form the next recording line. It is something to do.
On the other hand, the line-type ink jet recording apparatus has a configuration in which nozzles are formed substantially in the entire width direction of printing paper, and performs recording while transporting the paper without scanning in the width direction.

The line-type ink jet recording apparatus forms one line in the width direction at a time, so there is an advantage that the recording speed is fast. However, since the entire head is large, the entire apparatus becomes large, and further, the resolution is high. In order to perform recording, the arrangement of the nozzles themselves must be made high in density, and this is actually difficult because of the obstacle that the manufacturing cost increases.
On the other hand, since the serial type ink jet recording apparatus forms an image with a relatively small head, there is an advantage that the apparatus cost is low, and many serial type ink jet printers are currently put into practical use.

In the serial type ink jet recording apparatus, the printing speed is determined by the resolution of the target image, the nozzle density, the driving frequency for forming dots, the sub-scanning speed, and the like.
Among these, the nozzle density is affected by the processing accuracy of the nozzle, liquid chamber, flow path, actuator, and the like, so there is a limit to increasing it.
In particular, in the case of inkjet using a piezo element, the only way to divide and form channels corresponding to nozzles is to perform mechanical processing such as dicing, or to form a thin film PZT by printing. As a result, the nozzle density becomes lower than the so-called bubble jet (registered trademark) method (or thermal ink jet method). Note that the upper limit of the nozzle density of an inkjet head using a piezo element is conventionally about 360 dpi.

By the way, in order to improve the printing speed, it is ideal to form the printing area by one main scanning.
This will be specifically described. For example, when a head with a nozzle density of 300 dpi is applied to form an image with a resolution of 300 dpi in the sub-scanning direction, one scan may be performed in the moving direction of the head (main scanning direction). When an image is created, the image creation speed becomes slow because it is necessary to fill the image by a so-called interlace method in which two main scans and one sub-scan (paper conveyance) are performed.

  Also in the main scanning direction, as a method of forming one line in the main scanning direction, a method of forming by one main scanning (one pass printing) and a method of forming by plural times of main scanning (so-called multi-scanning). However, the printing speed of the one-pass printing that can be formed by one main scanning is faster.

  However, in the case of an ink jet printer using a piezo element, as described above, the nozzle density is not sufficiently high from a practical point of view. Therefore, in order to improve the recording speed, a line type ink jet recording apparatus or a serial type ink jet recording is used. When an image is created by applying the 1-pass non-interlace method in the apparatus, there is a problem that the resolution is lowered and a high-quality image cannot be obtained.

In view of the technical problems described above, conventionally, a technique for improving character quality even at low resolution by performing jaggy correction processing on characters has been disclosed (for example, see Patent Document 1 below). .
However, the jaggy correction processing is a technique mainly for improving the quality of characters, and has a drawback that it cannot obtain a quality improvement effect for other, for example, graphics and photographs.

JP 2003-334938 A

  Therefore, in the present invention, in order to solve the above-described conventional technical problems, both the line-type inkjet method and the serial-type inkjet method can perform high-speed printing, enable high resolution, and obtain high image quality. And a printing method using the same are provided.

  According to the first aspect of the present invention, a head unit including a nozzle that ejects ink for printing onto the surface of the printing paper is mounted, and the head unit corresponding to the width of the printing paper is fixed. A line-type ink jet recording apparatus that performs printing with ink droplets ejected from a head unit on the entire printing paper by carrying it, and has a resolution in the printing paper feeding direction according to the ink absorbency of the printing paper. There is provided a line type ink jet recording apparatus characterized by comprising means for controlling and converting image data according to the resolution in the printing paper feeding direction.

  According to a second aspect of the present invention, the line type ink jet recording apparatus according to the first aspect, further comprising means for controlling the resolution in the print paper feed direction by changing the feed speed of the print paper. I will provide a.

  According to a third aspect of the present invention, the line-type ink jet according to the first aspect, further comprising means for changing the period of ejecting ink from the nozzles to control the resolution in the printing paper feed direction. A recording device is provided.

  According to a fourth aspect of the present invention, a nozzle having a plurality of ejection openings arranged in parallel for ejecting the same color ink is provided, and the position of the printing dot is adjusted by selecting the ejection opening for ejecting the ink. The line-type ink jet recording apparatus according to claim 1, further comprising means for controlling a resolution in the printing paper feeding direction.

  According to a fifth aspect of the present invention, there is provided means for controlling the resolution in the printing paper feed direction by hitting dots between dots hit earlier in multi-pass printing. A line-type ink jet recording apparatus according to 1 is provided.

According to a sixth aspect of the invention, there is provided means for setting the resolution in the print paper feeding direction to n times the head resolution (1.0 ≦ n ≦ X / a) in accordance with the absorbency of the print paper. A line type ink jet recording apparatus according to claim 1, wherein the line type ink jet recording apparatus is provided.
However, X is 2400 dpi and a is the head resolution.

In the invention of claim 7, the ink transfer amount at a contact time of 100 ms measured with a dynamic scanning absorption meter in an environment of 23 ° C. and 50% RH is ² to 40 ml / m ² , and at a contact time of 400 ms. Means for setting the resolution in the paper feed direction to m times the head resolution (1.0 ≦ m ≦ X / 2a) when printing on printing paper having an ink transfer amount of 3 to 50 ml / m ² ; A line type ink jet recording apparatus according to claim 1, wherein the line type ink jet recording apparatus is provided. However, X is 2400 dpi and a is the head resolution.

  The invention according to claim 8 is characterized by comprising means for changing the resolution in the paper feed direction and the resolution in the direction orthogonal to the paper feed direction by performing interlaced printing. A line type inkjet recording apparatus according to any one of items 1 to 7 is provided.

  According to a ninth aspect of the invention, there is provided means for controlling the amount of ejected ink droplets so that the amount of ink adhering per unit area is constant. A line-type ink jet recording apparatus according to one item is provided.

  According to a tenth aspect of the present invention, there is provided means for detecting the degree of ink dot spread on the printing paper and adjusting the ink adhesion amount per unit area. A line-type ink jet recording apparatus according to any one of the above is provided.

  According to an eleventh aspect of the present invention, a head unit including a nozzle that ejects ink to be printed onto a surface of a printing paper is mounted, the head unit is scanned perpendicularly to a feeding direction of the printing paper, and the head A serial type ink jet recording apparatus that performs recording with ink droplets ejected from a unit, and when performing image formation by only one head unit scan, according to the absorbency of the printing paper, There is provided a serial type ink jet recording apparatus characterized by comprising means for controlling the resolution, converting image data in accordance with the resolution in the main scanning direction, and printing the image data.

  12. The serial type ink jet recording apparatus according to claim 11, further comprising means for controlling the resolution in the main scanning direction by changing the moving speed of the head unit. I will provide a.

  The invention of claim 13 further comprises means for controlling the resolution in the main scanning direction by changing the period of ejecting ink from the nozzles. A recording device is provided.

  In the fourteenth aspect of the present invention, a nozzle having a plurality of ejection openings arranged in parallel for ejecting the same color ink is provided, and the position of the printing dot is adjusted by selecting the ejection opening for ejecting the ink. The serial ink jet recording apparatus according to claim 11, further comprising means for controlling the resolution in the main scanning direction.

  According to a fifteenth aspect of the present invention, there is provided means for controlling the resolution in the main scanning direction by hitting dots between dots previously hit by multi-pass printing. Item 12. A serial ink jet recording apparatus according to Item 11.

  According to a sixteenth aspect of the invention, there is provided means for setting the resolution in the main scanning direction to n times the head resolution (1.0 ≦ n ≦ X / a) in accordance with the absorbency of the printing paper. A serial type ink jet recording apparatus according to any one of claims 11 to 15 is provided. However, X is 2400 dpi and a is the head resolution.

In the invention of claim 17, the ink transfer amount at a contact time of 100 ms measured with a dynamic scanning absorption meter in an environment of 23 ° C. and 50% RH is ² to 40 ml / m ² , and at a contact time of 400 ms. When printing on a printing paper having an ink transfer amount of 3 to 50 ml / m ² , means for setting the resolution in the main scanning direction to m times the head resolution (1.0 ≦ m ≦ X / 2a). The serial type ink jet recording apparatus according to claim 11, wherein the serial type ink jet recording apparatus is provided. However, X is 2400 dpi and a is the head resolution.

  According to an eighteenth aspect of the invention, there is provided means for changing the resolution in the main scanning direction and the sub-scanning direction by performing interlaced printing, respectively. A serial type ink jet recording apparatus according to one item is provided.

  According to a nineteenth aspect of the invention, there is provided means for controlling the amount of ejected ink droplets so that the amount of ink adhering per unit area is constant. A serial type ink jet recording apparatus according to one item is provided.

  The invention according to claim 20 comprises means for detecting the degree of ink dot spread on the printing paper and adjusting the amount of ink adhering per unit area. A serial type ink jet recording apparatus according to any one of the above is provided.

  In a twenty-first aspect of the present invention, a head unit having a nozzle for ejecting ink for printing onto the surface of the printing paper is mounted, and the printing paper is transported in a state where the head unit corresponding to the width of the printing paper is fixed. A printing method using a line-type inkjet recording apparatus that performs printing with ink droplets ejected from a head unit over the entire printing paper, wherein the printing paper is fed in a feeding direction according to the absorbency of the printing paper. Provided is a printing method characterized by controlling the resolution, converting image data in accordance with the resolution in the printing paper feed direction, and printing the image data.

  In a twenty-second aspect of the present invention, a head unit including a nozzle that ejects ink to be printed onto a surface of a printing paper is mounted, the head unit is scanned perpendicularly to a feeding direction of the printing paper, and the head unit A printing method using a serial type ink jet recording apparatus that performs recording with ejected ink droplets, and when image formation is performed only by one scan of the head unit, depending on the absorbency of the printing paper, Provided is a printing method characterized by controlling the resolution in the scanning direction, converting the image data according to the resolution in the main scanning direction, and printing it.

  According to a twenty-third aspect of the invention, there is provided a control program that causes an inkjet recording apparatus to execute the printing method according to the twenty-first or twenty-second aspect.

  According to a twenty-fourth aspect of the present invention, the ink used in the ink jet recording apparatus according to any one of the first to twentieth aspects includes at least water, a colorant, and a wetting agent. An ink is provided.

  According to a twenty-fifth aspect of the invention, there is provided the ink according to the twenty-fourth aspect, wherein the surface tension at 25 ° C. is 15 to 40 mN / m.

  According to a twenty-sixth aspect of the present invention, there is provided the ink according to the twenty-fourth or twenty-fifth aspect, which contains a fluorine-based surfactant.

  According to the first to eighth aspects of the present invention, in the line type ink jet recording apparatus, the beading is performed by changing the resolution in the paper feeding direction and the resolution in the direction perpendicular to the paper feeding according to the absorbability of the printing paper. And white spots can be effectively avoided, and high-resolution images can be printed.

  According to the ninth aspect of the present invention, even when the paper feed resolution is increased, the amount of ink adhering per unit area is the same, so that occurrence of beading can be avoided.

  According to the invention of claim 10, since the ink adhesion amount is controlled in accordance with the dot spread rate of the printing paper, it is possible to prevent white spots of the image due to the ink droplets not bleeding and the dot diameter being reduced.

  According to the invention of claims 11 to 18, in the serial type ink jet recording apparatus, by controlling the resolution in the main scanning direction and the resolution in the sub scanning direction in accordance with the absorbability of the printing paper, It is possible to prevent the occurrence of white spots and to print high resolution images.

  According to the nineteenth aspect of the invention, even when the main scanning resolution is increased, the amount of ink adhering per unit area is the same, so that occurrence of beading can be effectively avoided.

  According to the twentieth aspect of the invention, since the ink adhesion amount is changed in accordance with the dot spread rate of the printing paper, the occurrence of white spots in the image due to the ink droplet bleeding and the dot diameter being reduced effectively. I was able to avoid it.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following examples.
Schematic diagrams of an example of the ink jet recording apparatus of the present invention are shown in FIG. 1, FIG. 2, and FIG.
1 is a schematic configuration diagram of a general inkjet recording apparatus, and FIG. 2 is a schematic configuration diagram of a so-called serial type inkjet recording apparatus that performs recording by scanning a head unit on a printing paper. 1 shows a schematic configuration diagram of a so-called line-type ink jet recording apparatus in which a print paper width head unit is fixed and recording is performed only by transporting paper.

  The ink jet recording apparatus of the present invention includes an image forming unit 2 and the like inside the apparatus main body 1, and a large number of recording media (hereinafter referred to as “printing paper”) 3 below the apparatus main body 1. A stackable paper feed tray 4 is provided, the print paper 3 fed from the paper feed tray 4 is taken in, and a required image is recorded by the image forming unit 2 while the print paper 3 is transported by the transport mechanism 5. Thereafter, the paper is discharged to a paper discharge tray 6 mounted on the side of the apparatus main body 1.

  Further, the ink jet recording apparatus of the present invention includes a duplex unit 7 that can be attached to and detached from the apparatus main body 1. When performing duplex printing, the sheet 3 is transported in the reverse direction by the transport mechanism 5 after the printing on one surface (front surface) is completed. Then, the sheet is taken into the duplex unit 7 and reversed so that the other side (back side) is sent to the transport mechanism 5 again as a printable side, and the sheet 3 is discharged to the discharge tray 6 after the other side (back side) printing is completed. Has been made.

2, the image forming unit 2 holds the carriage 13 slidably on the guide shafts 11 and 12, and the main scanning motor (not shown) holds the carriage 13 on the printing paper. The recording is performed by moving (main scanning) in a direction orthogonal to the conveyance direction 3.
In the line type ink jet recording apparatus of FIG. 3, the image forming unit 2 is fixed and recording is performed only by transporting (scanning) the paper.

The image forming unit 2 is equipped with a recording head 14 composed of a droplet discharge head in which nozzle holes, which are a plurality of discharge ports for discharging droplets, are arranged, and supplies liquid to the recording head 14. An ink cartridge 15 is mounted detachably.
In addition, a configuration may be adopted in which a sub tank is mounted instead of the ink cartridge 15 so that ink is replenished and supplied from the main tank to the sub tank.

Here, as the recording head 14, for example, in addition to the four basic colors of black (K), cyan (C), magenta (M), and yellow (Y), red (R), green (G), and blue (G An inkjet head for each color that ejects ink droplets of a special color such as B) or one inkjet head having a plurality of nozzle rows that eject ink droplets of these colors can be applied.
The number of colors and the arrangement order are not limited to these.

  As the ink jet head constituting the recording head 14, a piezoelectric actuator such as a piezoelectric element, a thermal actuator that utilizes a phase change caused by film boiling of a liquid using an electrothermal transducer such as a heating resistor, and a metal phase change caused by a temperature change. A shape memory alloy actuator to be used, an electrostatic actuator using an electrostatic force, or the like provided as energy generating means for discharging ink can be applied.

The printing paper 3 in the paper feeding tray 4 is separated one by one by a paper feeding roller (half-moon roller) 21 and a separation pad (not shown), fed into the apparatus main body 1 and fed into the transport mechanism 5.
The transport mechanism 5 guides the fed paper 3 along the guide surface 23 a and guides the paper 3 fed from the duplex unit 7 along the guide surface 23 b and the paper 3. A conveying roller 24 that conveys, a pressure roller 25 that presses the sheet 3 against the conveying roller 24, a guide member 26 that guides the sheet 3 toward the conveying roller 24, and a sheet 3 that is returned when duplex printing is performed on the duplex unit 7. And a pressing roller 28 that presses the paper 3 fed from the conveying roller 24.

Further, in order to convey the sheet 3 with the recording head 14 while maintaining the flatness of the sheet 3, the conveyance mechanism 5 charges the conveyance belt 33, which is stretched between the driving roller 31 and the driven roller 32, and the conveyance belt 33. Charging roller 34, a guide roller 35 facing the charging roller 34, a guide member (plastic template) for guiding the conveying belt 33 at a portion facing the image forming unit 2, and a recording attached to the conveying belt 33. It has a cleaning roller made of a porous body or the like, which is a cleaning means for removing liquid (ink).
The transport belt 33 is an endless belt, is stretched between a driving roller 31 and a driven roller (tension roller) 32, and circulates in an arrow direction (paper transport direction) in FIGS. It is configured as follows.

The transport belt 33 may have a single-layer structure, but as shown in FIG. 4, a two-layer structure including a first layer (outermost layer) 33a and a second layer (back layer) 33b, or a structure of three or more layers. can do.
For example, the transport belt 33 is a surface layer that is a sheet adsorbing surface formed of a pure resin material having a thickness of about 40 μm that is not subjected to resistance control, for example, ETFE pure material, and resistance control by carbon using the same material as the surface layer. It can be comprised with the performed back layer (medium resistance layer, earth layer).

The charging roller 34 is disposed so as to come into contact with the surface layer of the transport belt 33 and to rotate following the rotation of the transport belt 33.
A high voltage is applied to the charging roller 34 from a high voltage circuit (high voltage power source, not shown) in a predetermined pattern.
A paper discharge roller 38 for sending the printing paper 3 on which an image is recorded to the paper discharge tray 6 is disposed on the downstream side from the transport mechanism 5.

  In the ink jet recording apparatus having the above-described configuration, the conveyance belt 33 circulates in the direction indicated by the arrow in the figure, and is positively charged by coming into contact with the charging roller 34 to which a high potential applied voltage is applied. In this case, the charging roller 34 is charged at a predetermined charging pitch by switching the polarity at predetermined time intervals.

  Here, when the printing paper 3 is fed onto the conveying belt 33 charged to a high potential, the inside of the printing paper 3 is in a polarized state, and the electric charge having the opposite polarity to the electric charge on the conveying belt 33 is applied to the printing paper 3. The charge on the belt 33 and the charge on the printing paper 3 to be conveyed are electrostatically attracted to each other, and the printing paper 3 is electrostatically attracted to the conveyance belt 33. Will be absorbed. In this way, the printing paper 3 that is strongly adsorbed to the transport belt 33 is calibrated for warping and unevenness, and a highly flat surface is formed.

In the serial type ink jet recording apparatus, ink droplets that are droplets are applied to the stopped printing paper 3 by driving the recording head 14 according to the image signal while moving the printing paper 3 by circling the transport belt 33. Is ejected to record one line, and after the printing paper 3 is conveyed by a predetermined amount, the next line is recorded.
In the line type ink jet recording apparatus, recording is performed by ejecting ink droplets as droplets while moving the printing paper 3 by circling the transport belt 33.
The printing paper 3 on which an image is recorded as described above is discharged to the paper discharge tray 6 by the paper discharge roller 38.

Next, the operation when recording is performed by changing the resolution in the paper feeding direction and the main scanning resolution will be described by taking a line type ink jet recording apparatus as an example.
Note that the following operations are controlled by a program that drives a computer installed in the recording apparatus, and can be set as appropriate according to a desired image.

  As an example of a method of changing the resolution in the paper feed direction to 1200 dpi, which is twice as high as the head resolution of 600 dpi and the standard paper feed direction resolution of 600 dpi (FIG. 5), the ink ejection cycle is not changed and the paper feed speed is halved. (FIGS. 6A and 6B), the paper feed speed is not changed, and the ink jetting period is halved (FIGS. 7A and 7B), the paper feed speed. The ink ejection cycle is not changed, and the head unit is arranged in two rows and dots are printed alternately by each head unit (FIG. 8: printed by the head unit A as head units A and B). (Represented as a gray dot, and a dot printed with the head unit B as a black dot), draw the paper once recorded, and place dots between the printed dots Method of performing pass printing (Fig. 9:. The first pass black mark photographed dot in represent dots photographed mark in the second pass in gray) it is.

As an example of operation when the resolution in the sub-scanning direction is changed to 2 times, after recording once, the paper is pulled in again, the printing paper is shifted by a resolution of 1200 dpi that is twice the head resolution, the paper is conveyed again, and the printing is performed. There is a method (FIG. 10) of hitting dots between copied dots.
Here, when the resolution is doubled, the image data is also printed with the resolution doubled.
When printing is performed on plain paper with a head resolution of 600 dpi, a standard paper feed direction resolution of 600 dpi, and an ink droplet amount of 10 pl, where the paper has high absorbency and dots are likely to spread, dots as shown in FIG. 11 are printed.
If the paper feed resolution is 900 dpi, which is 1.5 times 600 dpi, dots as shown in FIG. 12 are shot and the resolution is improved.
When the paper feed resolution is 1200 dpi, dots as shown in FIG. 13 are shot, but the dot overlap becomes large and beading occurs. Therefore, by setting the ink droplet amount to 5 pl and making the ink amount per area constant, the dot diameter is reduced as shown in FIG. 14, and the occurrence of beading can be avoided.
Also, when printing on coated paper with a paper feed resolution of 600 dpi, where the paper absorbability is low and the dots are difficult to spread (about 1/2 of plain paper), the gap between dots is large and the solid image is not filled as shown in FIG. White spots occur.
Therefore, if the amount of ink droplets is increased in accordance with the difficulty of spreading the dots and the ink droplets are 20 pl, the result is as shown in FIG.
Here, beading is a phenomenon in which irregular dots and density increase occur because adjacent dots are connected on the recording paper, and the image quality is impaired.
Note that the above ink droplet amount is a value given as an example for explaining the present invention, and is different from an accurate value.
It was also confirmed that the resolution changing method by the line type ink jet recording apparatus can be easily reflected to the serial type ink jet recording apparatus.

<Recording media (printing (recording) paper)>
A recording medium for printing by applying to the ink jet recording apparatus of the present invention will be described.
The recording medium has a structure in which a support and a coating layer are provided on at least one surface of the support, and other layers are formed as necessary.

In a recording medium, the transfer amount of the ink of the present invention at a contact time of 100 ms measured with a dynamic scanning absorption meter is ² to 40 ml / m ² , and more preferably ³ to 30 ml / m ^2. .
The transfer amount of pure water to the recording medium is preferably ² to 45 ml / m ² , more preferably ³ to 30 ml / m ² .
If the transfer amount of the ink and pure water at the contact time of 100 ms is too small, beading is likely to occur. If it is too large, the ink dot diameter after recording becomes too smaller than the desired diameter. There is.
The amount of transfer of the ink of the present invention to the recording medium at a contact time of 400 ms measured with a dynamic scanning absorption meter is 3 to 50 ml / m ² , and further 4 to 40 ml / m ^2. Is preferred.
The transfer amount of pure water to the recording medium is preferably 3 to 50 ml / m ² , and preferably 4 to
40 ml / m ² is more preferred.
If the amount of transfer at the contact time of 400 ms is too small, the drying property is insufficient, and thus spur marks may be easily generated. If the amount is too large, bleeding is likely to occur, and the gloss of the image area after drying is likely to occur. May become low.

Here, the dynamic scanning absorptiometer (DSA, Papa-Pagi Technical Journal, Vol. 48, May 1994, pp. 88-92, Kuju Shigenori) absorbs liquid in a very short time. It is a device that can measure accurately.
The dynamic scanning absorption meter reads the liquid absorption speed directly from the movement of the meniscus in the capillary, makes the sample a disk, and then scans the liquid absorption head in a spiral shape, and the scanning speed according to a preset pattern. Is automatically changed by a method in which the number of necessary points is measured with one sample. A liquid supply head for a paper sample is connected to a capillary via a Teflon (registered trademark) tube, and the position of the meniscus in the capillary is automatically read by an optical sensor. Specifically, the transfer amount of pure water or ink was measured using a dynamic scanning absorption meter (K350 series D type, manufactured by Kyowa Seiko Co., Ltd.). The transfer amount at the contact time of 100 ms and the contact time of 400 ms can be obtained by interpolation from the measured value of the transfer amount at the contact time adjacent to each contact time. The measurement was performed at 23 ° C. and 50% RH.

-Support-
There is no restriction | limiting in particular as said support body which comprises a recording medium, According to the objective, it can select suitably. Examples thereof include sheet-like substances such as paper mainly composed of wood fibers, and nonwoven fabrics mainly composed of wood fibers and synthetic fibers.

There is no restriction | limiting in particular as said paper, According to the objective, it can select suitably according to the objective, For example, wood pulp, waste paper pulp, etc. are applicable. Examples of the wood pulp include hardwood bleached kraft pulp (LBKP), softwood bleached kraft pulp (NBKP),
NBSP, LBSP, GP, TMP, etc. are mentioned.

As the raw material of the used paper pulp, the white paper, ruled white, cream white, card, special white, medium white, imitation, fair white, Kent, white, as shown in the used paper standard quality standard table of the used paper recycling promotion center Art, special upper limit, separate upper limit, newspaper, magazine, etc. are listed.
Specifically, printer paper such as non-coating computer paper, thermal paper, and pressure-sensitive paper as information-related paper; OA waste paper such as PPC paper; coating of art paper, coated paper, finely coated paper, matte paper, etc. Paper: High quality paper, color quality, notebook, notepaper, wrapping paper, fancy paper, medium quality paper, newsprint, reprint paper, super paper, imitation paper, pure white roll paper, uncoated paper such as milk carton, etc. Examples of used paper and paperboard include chemical pulp paper and high-yield pulp-containing paper. These may be used alone or in combination of two or more.

The waste paper pulp is generally produced from a combination of the following four steps.
(1) For disaggregation, waste paper is treated with mechanical force and chemicals with a pulper to loosen it into a fibrous form, and the printing ink is peeled from the fiber.
(2) Dust removal is to remove foreign matter (plastic etc.) and dust contained in waste paper with a screen, cleaner or the like.
(3) In the deinking, the printing ink peeled off from the fiber using a surfactant is removed from the system by a flotation method or a cleaning method.
(4) Bleaching increases the whiteness of the fiber using an oxidizing action or a reducing action.
When mixing the used paper pulp, the mixing ratio of the used paper pulp in the total pulp is preferably 40% or less from the viewpoint of curling after recording.

  As the internal filler used for the support, for example, a conventionally known pigment can be applied as a white pigment. Examples of the white pigment include light calcium carbonate, heavy calcium carbonate, kaolin, clay, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, aluminum silicate, diatomaceous earth, White inorganic pigments such as calcium silicate, magnesium silicate, synthetic silica, aluminum hydroxide, alumina, lithopone, zeolite, magnesium carbonate, magnesium hydroxide; styrene plastic pigment, acrylic plastic pigment, polyethylene, microcapsule, urea resin And organic pigments such as melamine resin. These may be used individually by 1 type and may use 2 or more types together.

  Examples of the internally added sizing agent used for making the support include neutral rosin sizing agents used for neutral papermaking, alkenyl succinic anhydride (ASA), alkyl ketene dimer (AKD), and petroleum resins. System sizing agents and the like. Among these, a neutral rosin sizing agent or alkenyl succinic anhydride is particularly preferable. The alkyl ketene dimer may be added in a small amount because of its high size effect, but the friction coefficient on the surface of the recording paper (media) is low and slippery, which is not preferable from the viewpoint of transportability during ink jet recording. There is.

-Coating layer-
The coating layer contains a pigment and a binder (binder), and if necessary, contains a surfactant and other components.

As the pigment, an inorganic pigment or a combination of an inorganic pigment and an organic pigment can be used.
Examples of the inorganic pigment include kaolin, talc, heavy calcium carbonate, light calcium carbonate, calcium sulfite, amorphous silica, titanium white, magnesium carbonate, titanium dioxide, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, Examples thereof include zinc hydroxide and chlorite. Among these, kaolin is particularly preferable because it has excellent glossiness and can be made close to a paper for offset printing.
The kaolin includes delaminated kaolin, calcined kaolin, engineered kaolin by surface modification, etc. In consideration of gloss expression, the particle size distribution is such that the ratio of the particle size is 2 μm or less is 80% by mass or more. It is preferable to apply the one in which the kaolin has 50% by mass or more of the entire kaolin.
The amount of kaolin added is preferably 50 parts by mass or more with respect to 100 parts by mass of the total pigment in the coating layer. When the addition amount is less than 50 parts by mass, a sufficient effect on glossiness may not be obtained. The upper limit of the addition amount is not particularly limited, but is preferably 90 parts by mass or less from the viewpoint of coating suitability in consideration of the fluidity of kaolin, particularly the thickening under high shear force.

Examples of the organic pigment include water-soluble dispersions such as styrene-acrylic copolymer particles, styrene-butadiene copolymer particles, polystyrene particles, and polyethylene particles. Two or more of these organic pigments may be mixed.
The addition amount of the organic pigment is preferably 2 to 20 parts by mass with respect to 100 parts by mass of the total pigment in the coating layer. Since the organic pigment is excellent in gloss expression and its specific gravity is smaller than that of an inorganic pigment, it is possible to obtain a coating layer that is bulky, high gloss, and has good surface coverage.
When the addition amount is less than 2 parts by mass, the above effect cannot be obtained. When the addition amount exceeds 20 parts by mass, the fluidity of the coating liquid deteriorates, leading to a decrease in coating operability, and from the cost aspect. There is also a problem that it is not economical.
The organic pigment includes a solid type, a hollow type, a donut type, and the like in terms of its form, but the average particle size is 0.2 in view of the balance of gloss development, surface coverage, and fluidity of the coating liquid. A hollow mold having a porosity of 40% or more is more preferable.

As the binder, an aqueous resin is preferably used.
As the aqueous resin, at least one of a water-soluble resin and a water-dispersible resin is preferably used.
There is no restriction | limiting in particular as said water-soluble resin, According to the objective, it can select suitably, For example, modified products of polyvinyl alcohol, such as polyvinyl alcohol, anion modified polyvinyl alcohol, cation modified polyvinyl alcohol, acetal modified polyvinyl alcohol; Polyurethane; Pyrrolidone and polyvinylpyrrolidone and vinyl acetate copolymer, vinylpyrrolidone and dimethylaminoethyl / methacrylic acid copolymer, quaternized vinylpyrrolidone / dimethylaminoethyl / methacrylic acid copolymer, vinylpyrrolidone and methacrylamidopropyl Modified products of polyvinylpyrrolidone such as a copolymer of trimethylammonium chloride; cellulose such as carboxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose; Modified cellulose such as hydroxyethyl cellulose; polyester, polyacrylic acid (ester), melamine resin, or synthetic resins such as these modified products, polyester and polyurethane copolymer; poly (meth) acrylic acid, poly ( Examples thereof include (meth) acrylamide, oxidized starch, phosphate esterified starch, self-modified starch, cationized starch, or various modified starches, polyethylene oxide, sodium polyacrylate, and sodium alginate. These may be used alone or in combination of two or more.
Among these, from the viewpoint of ink absorbability, polyvinyl alcohol, cation-modified polyvinyl alcohol, acetal-modified polyvinyl alcohol, polyester, polyurethane, a copolymer of polyester and polyurethane, and the like are particularly preferable.

There is no restriction | limiting in particular as said water dispersible resin, According to the objective, it can select suitably. For example, polyvinyl acetate, ethylene-vinyl acetate copolymer, polystyrene, styrene- (meth) acrylic acid ester copolymer, (meth) acrylic acid ester polymer, vinyl acetate- (meth) acrylic acid (ester) copolymer Examples thereof include a polymer, a styrene-butadiene copolymer, an ethylene-propylene copolymer, a polyvinyl ether, and a silicone-acrylic copolymer.
Further, it may contain a crosslinking agent such as methylolated melamine, methylolated urea, methylolated hydroxypropylene urea, or isocyanate, or may be a copolymer containing units such as N-methylolacrylamide and having a self-crosslinking property. A plurality of these water-based resins can be used simultaneously.
2-100 mass parts is preferable with respect to 100 mass parts of said pigments, and, as for the addition amount of the said aqueous resin, 3-50 mass parts is more preferable. The amount of the aqueous resin added is determined so that the liquid absorption characteristics of the recording medium fall within a desired range.

When a water-dispersible colorant is used as the colorant, the cationic organic compound is not necessarily added, but is not particularly limited and can be appropriately selected and used depending on the purpose.
For example, a primary to tertiary amine, quaternary ammonium salt monomer or oligomer that reacts with a sulfonic acid group, a carboxyl group, an amino group, or the like in a direct dye or acidic dye in water-soluble ink to form an insoluble salt. Examples thereof include polymers. Among these, an oligomer or a polymer is preferable.

Examples of the cationic organic compound include dimethylamine / epichlorohydrin polycondensate, dimethylamine / ammonia / epichlorohydrin condensate, poly (trimethylaminoethyl methacrylate / methyl sulfate), diallylamine hydrochloride / acrylamide copolymer, (Diallylamine hydrochloride / sulfur dioxide), polyallylamine hydrochloride, poly (allylamine hydrochloride / diallylamine hydrochloride), acrylamide / diallylamine copolymer, polyvinylamine copolymer, dicyandiamide, dicyandiamide / ammonium chloride / urea / formaldehyde condensate , Polyalkylene polyamine dicyandiamide ammonium salt condensate, dimethyl diallyl ammonium chloride, polydiallyl methylamine hydrochloride, poly (diallyl dimethyl ester) Ruammonium chloride), poly (diallyldimethylammonium chloride / sulfur dioxide), poly (diallyldimethylammonium chloride / diallylamine hydrochloride derivative), acrylamide / diallyldimethylammonium chloride copolymer, acrylate / acrylamide / diallylamine hydrochloride copolymer Products, ethyleneimine derivatives such as polyethyleneimine and acrylicamine polymers, and polyethyleneimine alkylene oxide modified products. These may be used individually by 1 type and may use 2 or more types together.
Among these, low molecular weight cationic organic compounds such as dimethylamine / epichlorohydrin polycondensate and polyallylamine hydrochloride and other relatively high molecular weight cationic organic compounds such as poly (diallyldimethylammonium chloride) It is preferable to use in combination. By using in combination, the image density can be improved and feathering can be further reduced as compared with the case of single use.

The cation equivalent of the cationic organic compound by colloid titration method (using polyvinyl potassium sulfate and toluidine blue) is preferably 3 to 8 meq / g.
It was confirmed that by setting the cation equivalent within the above range, good results can be obtained within the dry adhesion range.
Here, in the measurement of the cation equivalent by the colloid titration method, the cationic organic compound is diluted with distilled water to a solid content of 0.1% by mass, and pH adjustment is not performed.

The dry adhesion amount of the cationic organic compound is preferably 0.3 to 2.0 g / m ² . When the dry adhesion amount of the cationic organic compound is less than 0.3 g / m ² , there is a possibility that sufficient image density improvement and feathering reduction effects cannot be obtained.

There is no restriction | limiting in particular as said surfactant, According to the objective, it can select suitably, Any of an anionic active agent, a cationic active agent, an amphoteric active agent, and a nonionic active agent can be used.
Of these, nonionic active agents are particularly preferred. By adding the surfactant, the water resistance of the image is improved, the image density is increased, and bleeding is improved.

Examples of the nonionic activator include higher alcohol ethylene oxide adducts, alkylphenol ethylene oxide adducts, fatty acid ethylene oxide adducts, polyhydric alcohol fatty acid ester ethylene oxide adducts, higher aliphatic amine ethylene oxide adducts, and fatty acid amides. Ethylene oxide adduct, fat ethylene oxide adduct, polypropylene glycol ethylene oxide adduct, fatty acid ester of glycerol, fatty acid ester of pentaerythritol, fatty acid ester of sorbitol and sorbitan, fatty acid ester of sucrose, alkyl ether of polyhydric alcohol, Examples include fatty acid amides of alkanolamines. These may be used alone or in combination of two or more.
There is no restriction | limiting in particular as said polyhydric alcohol, According to the objective, it can select suitably. For example, glycerol, trimethylolpropane, pentaerythritol, sorbitol, sucrose and the like can be mentioned. As the ethylene oxide adduct, a product obtained by substituting a part of ethylene oxide with an alkylene oxide such as propylene oxide or butylene oxide is also effective as long as water solubility can be maintained. The substitution rate is preferably 50% or less. 4-15 are preferable and, as for HLB (hydrophilic / lipophilic ratio) of the said nonionic activator, 7-13 are more preferable.

  The addition amount of the surfactant is preferably 0 to 10 parts by mass, and more preferably 0.1 to 1.0 part by mass with respect to 100 parts by mass of the cationic organic compound.

  Other material components may be further added to the coating layer as necessary, as long as the objects and effects of the present invention are not impaired. Examples thereof include additives such as alumina powder, pH adjuster, preservative, and antioxidant.

The method for forming the coating layer is not particularly limited and can be appropriately selected depending on the purpose, and can be formed by a method of impregnating or applying a predetermined coating layer solution on the support.
The method for impregnating or applying the coating layer solution is not particularly limited and can be appropriately selected depending on the purpose. For example, it can coat using various coating machines, such as a conventional size press, a gate roll size press, a film transfer size press, a blade coater, a rod coater, an air knife coater, a curtain coater. Among these, from the viewpoint of cost, a method of impregnating or adhering using a conventional size press, a gate roll size press, a film transfer size press or the like installed in a paper machine and finishing on-machine is preferable.
There is no restriction | limiting in particular in the adhesion amount of the said coating layer liquid, Although it can select suitably according to the objective, 0.5-20 g / m < ² > is preferable at solid content, and 1-15 g / m < ² > is more preferable. If it is less than 0.5 g / m ² , the ink cannot be sufficiently absorbed, causing a problem that the ink overflows and character bleeding occurs, and if it exceeds 20 g / m ² , the texture of the paper is impaired and it becomes difficult to bend. This is because there is a problem that it becomes difficult to write with a writing instrument.
After the impregnation or coating, a drying treatment may be performed as necessary. In this case, the drying temperature is not particularly limited and may be appropriately selected depending on the intended purpose. Is preferred.

  The recording medium (recording paper) may further include a back layer on the back surface of the support, between the support and the coating layer, or another layer between the support and the back layer. A protective layer may be provided. Each of these layers may be a single layer or a plurality of layers.

The recording medium (recording paper) described above may be any of commercially available offset printing coated paper, gravure printing coated paper, etc., as well as inkjet recording media, as long as the liquid absorption property is within the above-described numerical value range. There may be.
The basis weight of the recording medium (recording paper) is preferably 50 to 250 g / m ² . If it is less than 50 g / m ² , so-called stiffness is insufficient, and it is likely to cause a conveyance failure such as the recording medium being jammed in the middle of the conveyance path.
On the other hand, if it exceeds 250 g / m ² , the stiffness becomes too large, so that the recording medium cannot be bent at the curved portion in the middle of the conveyance path, and a conveyance failure such as the recording medium being clogged is likely to occur.

Next, the ink applied to the ink jet recording apparatus of the present invention will be described.
The ink used in the ink jet recording apparatus of the present invention contains at least water, a colorant, and a wetting agent, and further contains a penetrating agent, a surfactant, and other additives as necessary. And

The ink has a surface tension at 25 ° C. of 15 to 40 mN / m, and preferably 20 to 35 mN / m.
When the surface tension is less than 15 / m, the nozzle plate of the ink jet recording apparatus is too wet to form ink droplets in a good state (particle formation), or the state of bleeding on the recording medium (medium) is remarkable. In other words, stable ink ejection cannot be obtained.
On the other hand, when the surface tension exceeds 40 mN / m, the ink does not sufficiently penetrate into the recording medium (medium), leading to occurrence of beading and a longer drying time.
In addition, the said surface tension can be measured at 25 degreeC using a platinum plate, for example using a surface tension measuring apparatus (Kyowa Interface Science Co., Ltd. product, CBVP-Z).

(Coloring agent)
Examples of the colorant include pigments, dyes and colored fine particles.
Examples of the colored fine particles include an aqueous dispersion of polymer fine particles containing a coloring material of at least one of a pigment and a dye.
Here, “containing the color material” may be either a state in which the color material is enclosed in the polymer fine particles or a state in which the color material is adsorbed on the surface of the polymer fine particles.
In the pigment-based ink of the present invention, it is not necessary that all the coloring material is encapsulated or adsorbed in the polymer fine particles, and the coloring material may be dispersed in the emulsion as long as the effect is not impaired. Good.
The color material is not particularly limited as long as it is water-insoluble or poorly water-soluble and can be adsorbed by the polymer, and can be appropriately selected according to the purpose.
Here, “water-insoluble or hardly water-soluble” means that the coloring material does not dissolve 10 parts by mass or more with respect to 100 parts by mass of water at 20 ° C. Further, “dissolve” means that separation or sedimentation of the coloring material is not observed in the surface layer or the lower layer of the aqueous solution visually.

The volume average particle diameter of the polymer fine particles (colored fine particles) containing the colorant is preferably 0.01 to 0.16 μm in the ink. If it is less than 0.01 μm, the fine particles easily flow, so that character bleeding occurs or the light resistance deteriorates.
On the other hand, when it exceeds 0.16 μm, the nozzle is likely to be clogged or the color developability deteriorates.
Examples of the colorant include water-soluble dyes, oil-soluble dyes, disperse dyes, and the like, pigments, and the like. Oil-soluble dyes and disperse dyes are preferable from the viewpoint of good adsorptivity and encapsulation, but pigments are preferable from the light resistance of the obtained image.
In addition, from the viewpoint of efficiently impregnating the polymer fine particles, each of the dyes is preferably dissolved in an organic solvent, for example, a ketone solvent in an amount of 2 g / liter or more, and more preferably 20 to 600 g / liter.
The water-soluble dye is a dye classified into an acid dye, a direct dye, a basic dye, a reactive dye, and a food dye in the color index, and preferably has excellent water resistance and light resistance. .

Examples of the acid dyes and food dyes include C.I. I. Acid Yellow 17, 23, 42, 44, 79, 142; C.I. I. Acid Red 1,8,13,14,18,2
6, 27, 35, 37, 42, 52, 82, 87, 89, 92, 97, 106, 111, 114, 115, 134, 186, 249, 254, 289; I. Acid Blue 9, 29, 45, 92, 249; I. Acid Black 1, 2, 7, 24, 26, 94; I. Food Yellow 3, 4; I. Food red 7, 9, 14; I. Food black 1, 2 etc. are mentioned.

  Examples of the direct dye include C.I. I. Direct yellow 1,12,24,26,33,44,50,86,120,132,142,144; I. Direct red 1,4,9,13,17,20,28,31,39,80,81,83,89,225,227; I. Direct orange 26, 29, 62, 102; I. Direct Blue 1, 2, 6, 15, 22, 25, 71, 76, 79, 86, 87, 90, 98, 163, 165, 199, 202; I. Direct black 19, 22, 32, 38, 51, 56, 71, 74, 75, 77, 154, 168, 171 and the like.

  Examples of the basic dye include C.I. I. Basic yellow 1, 2, 11, 13, 14, 15, 19, 21, 23, 24, 25, 28, 29, 32, 36, 40, 41, 45, 49, 51, 53, 63, 64, 65, 67, 70, 73, 77, 87, 91; C.I. I. Basic Red 2,12,13,14,15,18,22,23,24,27,29,35,36,38,39,46,49,51,52,54,59,68,69,70, 73, 78, 82, 102, 104, 109, 112; I. Basic blue 1,3,5,7,9,21,22,26,35,41,45,47,54,62,65,66,67,69,75,77,78,89,92,93, 105, 117, 120, 122, 124, 129, 137, 141, 147, 155; I. Basic black 2, 8 etc. are mentioned.

  Examples of the reactive dye include C.I. I. Reactive Black 3, 4, 7, 11, 12, 17; C.I. I. Reactive Yellow 1,5,11,13,14,20,21,22,25,40,47,51,55,65,67; I. Reactive Red 1,14,17,25,26,32,37,44,46,55,60,66,74,79,96,97; I. Reactive blue 1, 2, 7, 14, 15, 23, 32, 35, 38, 41, 63, 80, 95 etc. are mentioned.

Next, the pigment will be described in detail.
There is no restriction | limiting in particular as said pigment, According to the objective, it can select suitably, For example, any of an inorganic pigment and an organic pigment may be sufficient.
Examples of the inorganic pigment include titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, chrome yellow, and carbon black. Among these, carbon black is preferable. In addition, as said carbon black, what was manufactured by well-known methods, such as a contact method, a furnace method, and a thermal method, is mentioned, for example.

  Examples of organic pigments include azo pigments, polycyclic pigments, dye chelates, nitro pigments, nitroso pigments, and aniline black. Among these, azo pigments and polycyclic pigments are more preferable. Examples of the azo pigments include azo lakes, insoluble azo pigments, condensed azo pigments, and chelate azo pigments. Examples of the polycyclic pigment include phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, and quinofullerone pigments. Examples of the dye chelates include basic dye chelates and acidic dye chelates.

  There is no restriction | limiting in particular as a color of the said pigment, According to the objective, it can select suitably, For example, the thing for black, the thing for color, etc. are mentioned. These may be used individually by 1 type and may use 2 or more types together.

  Examples of the black color include carbon black (CI pigment black 7) such as furnace black, lamp black, acetylene black, channel black, copper, iron (CI pigment black 11), oxidation, and the like. Examples thereof include metals such as titanium and organic pigments such as aniline black (CI Pigment Black 1).

As for the color, for yellow ink, for example, C.I. I. Pigment Yellow 1 (Fast Yellow G), 3, 12 (Disazo Yellow AAA), 13, 14, 17, 23, 24, 34, 35, 37, 42 (Yellow Iron Oxide), 53, 55, 74, 81, 83 (Disazo Yellow HR), 95, 97, 98, 100, 101, 104, 108, 109, 110, 117, 120, 128, 138, 150, 153 and the like.
For magenta, for example, C.I. I. Pigment Red 1, 2, 3, 5, 17, 22 (Brilliant First Scarlet), 23, 31, 38, 48: 2 (Permanent Red 2B (Ba)), 48: 2 (Permanent Red 2B (Ca)), 48 : 3 (Permanent Red 2B (Sr)), 48: 4 (Permanent Red 2B (Mn)), 49: 1, 52: 2, 53: 1, 57: 1 (Brilliant Carmine 6B), 60: 1, 63: 1, 63: 2, 64: 1, 81 (Rhodamine 6G Lake), 83, 88, 92, 101 (Bengara), 104, 105, 106, 108 (Cadmium Red), 112, 114, 122 (Dimethylquinacridone), 123, 146, 149, 166, 168, 170, 172, 177, 178, 179, 185, 190, 193, 209, 2 19 etc. are mentioned.
For cyan, for example, C.I. I. Pigment Blue 1, 2, 15 (copper phthalocyanine blue R), 15: 1, 15: 2, 15: 3 (phthalocyanine blue G), 15: 4, 15: 6 (phthalocyanine blue E), 16, 17: 1, 56, 60, 63 and the like.
In addition, as the intermediate colors for red, green and blue, C.I. I. Pigment red 177, 194, 224, C.I. I. Pigment orange 43, C.I. I. Pigment violet 3, 19, 23, 37, C.I. I. And CI Pigment Green 7, 36.

As the pigment, a pigment in which at least one hydrophilic group is bonded to the surface of the pigment directly or through another atomic group, that is, a self-dispersing pigment that can be stably dispersed without using a dispersant is suitable. Used for.
By using such a pigment, a dispersant for dispersing the pigment becomes unnecessary. As the self-dispersing pigment, those having ionicity are preferable, and those having an anionic charge or those having a cationic charge are suitable.
The volume average particle diameter of the self-dispersing pigment is preferably 0.01 to 0.16 μm in the ink.

Examples of the anionic hydrophilic group include —COOM, —SO ₃ M, —PO ₃ HM, —PO ₃ M ₂ , —SO ₂ NH ₂ , —SO ₂ NHCOR (wherein M is a hydrogen atom) , R represents an alkyl group having 1 to 12 carbon atoms, a phenyl group which may have a substituent, or a naphthyl group which may have a substituent). Can be mentioned. Among these, -COOM, -SO ₃ M are preferred as being coupled to a color pigment surface.

Specific examples when “M” in the hydrophilic group is an alkali metal include lithium, sodium, potassium and the like.
Examples of the organic ammonium include mono to trimethyl ammonium, mono to triethyl ammonium, and mono to trimethanol ammonium.

As a method of obtaining the anionically charged color pigment, as a method of introducing —COONa to the color pigment surface, for example, a method of oxidizing the color pigment with sodium hypochlorite, a method of sulfonation, a diazonium salt The method of making it react is mentioned.
As the cationic hydrophilic group, for example, a quaternary ammonium group is preferable, and quaternary ammonium groups of the following formulas (1) to (11) are preferable.

There is no restriction | limiting in particular as a method of manufacturing the cationic self-dispersion type carbon black to which the said hydrophilic group was couple | bonded, According to the objective, it can select suitably.
As a specific example, as a method for bonding an N-ethylpyridyl group represented by the following formula (12), a method of treating carbon black with 3-amino-N-ethylpyridinium bromide can be mentioned.

The hydrophilic group may be bonded to the surface of carbon black via another atomic group.
Examples of other atomic groups at this time include an alkyl group having 1 to 12 carbon atoms, a phenyl group which may have a substituent, or a naphthyl group which may have a substituent.
Specific examples of the case where the above-described hydrophilic group is bonded to the surface of carbon black through another atomic group include, for example, —C ₂ H ₄ COOM (where M represents an alkali metal, quaternary ammonium), -PhSO ₃ M (however, Ph is a phenyl group, M is an alkali metal, represents a quaternary _{ammonium), - C 5 H 10 NH} 3+ , and the like.

In the present invention, a pigment dispersion using a pigment dispersant can also be applied.
As the pigment dispersant, as the hydrophilic polymer compound, in the natural system, vegetable polymers such as gum arabic, tragan gum, guar gum, karaya gum, locust bean gum, arabinogalactone, pectin, quince seed starch, alginic acid, carrageenan And seaweed polymers such as agar, animal polymers such as gelatin, casein, albumin and collagen, and microorganism polymers such as xanthene gum and dextran. In semi-synthetic systems, fiber polymers such as methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, carboxymethylcellulose, starch polymers such as sodium starch glycolate and sodium starch phosphate, sodium alginate, propylene glycol alginate And seaweed polymers such as
Pure synthetic systems include polyvinyl polymers such as polyvinyl alcohol, polyvinyl pyrrolidone, and polyvinyl methyl ether, non-crosslinked polyacrylamide, polyacrylic acid or alkali metal salts thereof, acrylic resins such as water-soluble styrene acrylic resins, and water-soluble styrene malees. Acid resin, water-soluble vinyl naphthalene acrylic resin, water-soluble vinyl naphthalene maleic resin, polyvinyl pyrrolidone, polyvinyl alcohol, alkali metal salt of β-naphthalene sulfonic acid formalin condensate, cationic functional group such as quaternary ammonium and amino group Examples thereof include a polymer compound having a salt in the side chain and a natural polymer compound such as shellac.
Among these, in particular, a polymer having a carboxyl group introduced from a homopolymer of acrylic acid, methacrylic acid, styrene acrylic acid or a copolymer of a monomer having another hydrophilic group is preferable as the polymer dispersant.
The weight average molecular weight of the copolymer is 3000 to 50000, preferably 5000 to 30000, and more preferably 7000 to 15000.
The mixing mass ratio of the pigment and the dispersant (pigment: dispersant) is preferably 1: 0.06 to 1: 3, and more preferably 1: 0.125 to 1: 3.

The amount of the colorant added to the ink is preferably 6 to 15% by mass, and more preferably 8 to 12% by mass.
When the addition amount is less than 6% by mass, the image density may be lowered due to a decrease in coloring power, or feathering or bleeding may be deteriorated due to a decrease in viscosity.
On the other hand, when the content exceeds 15% by mass, when the ink jet recording apparatus is left unattended, the nozzle is easily dried, non-ejection phenomenon occurs, or the permeability becomes too low due to excessively high viscosity. Further, since the dots do not spread, there is a possibility that the image density is lowered or a blurred image is formed.

(Wetting agent)
Next, the wetting agent will be described.
The wetting agent is not particularly limited and can be appropriately selected according to the purpose.
For example, at least one selected from polyol compounds, lactam compounds, urea compounds and saccharides is suitable.

Examples of the polyol compound include polyhydric alcohols, polyhydric alcohol alkyl ethers, polyhydric alcohol aryl ethers, nitrogen-containing heterocyclic compounds, amides, amines, sulfur-containing compounds, propylene carbonate, and ethylene carbonate. Is mentioned.
These may be used alone or in combination of two or more.

Examples of the polyhydric alcohols include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, 1,3-purpandiol, 1,3-butanediol, 1,4 butanediol, and 3-methyl- 1,3-butanediol 1,3-propanediol, 1,5-pentanediol, 1,6 hexanediol, glycerol, 1,2,6-hexanetriol, 1,2,4-butanetriol, 1,2,3 -Butanetriol, petriol and the like.
Examples of the polyhydric alcohol alkyl ethers include ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, and propylene glycol monoethyl ether. It is done.
Examples of the polyhydric alcohol aryl ethers include ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether.
Examples of the nitrogen-containing heterocyclic compound include N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethylimidazolidinone, and ε-caprolactam.
Examples of the amides include formamide, N-methylformamide, formamide, N, N-dimethylformamide and the like.
Examples of the amines include monoethanolamine, diethanolamine, triethanolamine, monoethylamine, diethylamine, and triethylamine.
Examples of the sulfur-containing compounds include dimethyl sulfoxide, sulfolane, thiodiethanol, and the like.
Among the above examples, glycerin, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol from the viewpoint of obtaining excellent effects on solubility and prevention of poor jetting characteristics due to moisture evaporation 1,3-butanediol, 2,3-butanediol, 1,4-butanediol, 3-methyl-1,3-butanediol 1,3-propanediol, 1,5-pentanediol, tetraethylene glycol, 1,6-hexanediol, 2-methyl-2,4-pentanediol, polyethylene glycol, 1,2,4-butanetriol, 1,2,6-hexanetriol, thiodiglycol, 2-pyrrolidone, N-methyl -2-pyrrolidone, N-hydroxyethyl 2-pyrrolidone is preferred.

Examples of the lactam compound include at least one selected from 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, and ε-caprolactam.
Examples of the urea compound include at least one selected from urea, thiourea, ethylene urea, and 1,3-dimethyl-2-imidazolidinone.
In general, the amount of urea added to the ink is preferably 0.5 to 50% by mass, and more preferably 1 to 20% by mass.

Examples of the saccharide include monosaccharides, disaccharides, oligosaccharides (including trisaccharides and tetrasaccharides), polysaccharides, and derivatives thereof.
In particular, glucose, mannose, fructose, ribose, xylose, arabinose, galactose, maltose, cellobiose, lactose, sucrose, trehalose, and maltotriose are preferable, and maltose, sorbitol, gluconolactone, and maltose are preferable.
The polysaccharide means a saccharide in a broad sense and is used to include substances widely existing in nature such as α-cyclodextrin and cellulose.
Examples of the saccharide derivatives include reducing sugars of the saccharides (for example, sugar alcohol (wherein general formula: HOCH ₂ (CHOH) _n CH ₂ OH (where n represents an integer of 2 to 5)) , Oxidized sugars (for example, aldonic acid, uronic acid, etc.), amino acids, thioic acids, etc. Among these, sugar alcohols are particularly preferable, and examples of such alcohols include maltitol, sorbit, and the like.

The content of the wetting agent in the ink is preferably 10 to 50% by mass, and more preferably 20 to 35% by mass.
If the content of the wetting agent is too small, the nozzle is likely to be dried and a droplet ejection failure may occur. On the other hand, if the amount is too large, the ink viscosity becomes high, and the appropriate viscosity range may be exceeded.

(Penetration agent)
Next, the penetrant will be described.
As the penetrant, water-soluble organic solvents such as polyol compounds and glycol ether compounds can be used. In particular, at least one of a polyol compound having 8 or more carbon atoms and a glycol ether compound is suitable.
If the polyol compound has less than 8 carbon atoms, sufficient penetrability cannot be obtained, and when performing double-sided printing, the recording medium (medium) is soiled or the ink does not spread on the recording medium (media). This is sufficient and the filling of the pixels becomes worse, so that there is a possibility that the character quality and the image density are lowered.
Examples of the polyol compound having 8 or more carbon atoms include 2-ethyl-1,3-hexanediol (solubility: 4.2% (25 ° C.)), 2,2,4-trimethyl-1,3-pentanediol. (Solubility: 2.0% (25 ° C.)) is preferred.

  The glycol ether compound is not particularly limited and may be appropriately selected depending on the intended purpose. For example, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol Examples include polyhydric alcohol alkyl ethers such as monomethyl ether and propylene glycol monoethyl ether; polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether.

  There is no restriction | limiting in particular in the addition amount of the said penetrant, Although it can select suitably according to the objective, 0.1-20 mass% is preferable, and 0.5-10 mass% is more preferable.

(Surfactant)
Next, the surfactant will be described.
The surfactant is not particularly limited and can be appropriately selected depending on the purpose.
For example, anionic surfactants, nonionic surfactants, amphoteric surfactants, fluorosurfactants and the like can be mentioned.

  Examples of the anionic surfactant include polyoxyethylene alkyl ether acetate, dodecylbenzene sulfonate, laurate, polyoxyethylene alkyl ether sulfate salt, and the like.

Examples of the nonionic surfactant include acetylene glycol surfactants, polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene alkyl esters, polyoxyethylene sorbitan fatty acid esters, and the like.
Examples of the acetylene glycol surfactant include 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol, , 5-dimethyl-1-hexyn-3-ol and the like.
Examples of commercially available acetylene glycol surfactants include Surfynol 104, 82, 465, 485, and TG manufactured by Air Products (USA).

Examples of amphoteric surfactants include lauryl aminopropionate, lauryl dimethyl betaine, stearyl dimethyl betaine, and lauryl dihydroxyethyl betaine.
Specific examples include lauryl dimethylamine oxide, myristyl dimethylamine oxide, stearyl dimethylamine oxide, dihydroxyethyl lauryl amine oxide, polyoxyethylene coconut oil alkyl dimethyl amine oxide, dimethyl alkyl (coconut) betaine, dimethyl lauryl betaine, and the like. .

  Among these surfactants, surfactants represented by the following formulas (13) to (18) are preferable.

R ₁ —O— (CH ₂ CH ₂ O) _h CH ₂ COOM (13)
However, in said formula, R < ₁ > represents an alkyl group and represents the C6-C14 alkyl group which may be branched. h represents an integer of 3 to 12. M represents one selected from alkali metal ions, quaternary ammonium, quaternary phosphonium, and alkanolamine.

However, the formula (14), R ₂ represents an alkyl group, an alkyl group which may be branched 5-16 carbon atoms. M represents one selected from alkali metal ions, quaternary ammonium, quaternary phosphonium, and alkanolamine.

However, in the above formula (15), R ₃ represents a hydrocarbon group, for example, an alkyl group branched carbon atoms and optionally 6-14. k represents an integer of 5 to 20.

R ₄ — (OCH ₂ CH ₂ ) _j OH (16)
However, in the above formula (16), R ₄ represents a hydrocarbon group, for example, an alkyl group having 6 to 14 carbon atoms. j represents an integer of 5 to 20.

However, the formula (17), R ₆ represents a hydrocarbon group, for example, represents an alkyl group which may be branched having 6 to 14 carbon atoms. L and p represent an integer of 1 to 20.

  However, in said Formula (18), q and r represent the integer of 0-40.

Hereinafter, the surfactant of the formula (13) is specifically shown in free acid form.
_{CH 3 (CH 2) 12 O} (CH 2 CH 2 O) 3 CH 2 COOH
_{CH 3 (CH 2) 12 O} (CH 2 CH 2 O) 4 CH 2 COOH
_{CH 3 (CH 2) 12 O} (CH 2 CH 2 O) 5 CH 2 COOH
CH ₃ (CH ₂ ) ₁₂ O (CH ₂ CH ₂ O) ₆ CH ₂ COOH

  Hereinafter, the surfactant of the formula (14) is specifically shown as a free acid type.

As the fluorine-based surfactant, those represented by the following formula are suitable.
CF ₃ CF ₂ (CF ₂ CF ₂ ) _m —CH ₂ CH ₂ O (CH ₂ CH ₂ O) _n H
However, m represents the integer of 0-10 in the said formula. n represents an integer of 1 to 40.

Examples of the fluorosurfactant include a perfluoroalkyl sulfonic acid compound, a perfluoroalkyl carboxylic compound, a perfluoroalkyl phosphate compound, a perfluoroalkyl ethylene oxide adduct, and a perfluoroalkyl ether group in the side chain. The polyoxyalkylene ether polymer compound etc. which have are mentioned.
Among these, the polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in the side chain has a low foaming property, and the bioaccumulation property of a fluorine compound, which has been regarded as a problem in recent years, is low and highly safe. preferable.

Examples of the perfluoroalkyl sulfonic acid compound include perfluoroalkyl sulfonic acid, perfluoroalkyl sulfonate, and the like.
Examples of the perfluoroalkyl carboxylic compounds include perfluoroalkyl carboxylic acids and perfluoroalkyl carboxylates.
Examples of the perfluoroalkyl phosphate compound include perfluoroalkyl phosphate esters and perfluoroalkyl phosphate salts.
The polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in the side chain includes a polyoxyalkylene ether polymer having a perfluoroalkyl ether group in the side chain, and a polyoxyalkylene ether having a perfluoroalkyl ether group in the side chain. Examples thereof include a sulfate salt of a polymer and a salt of a polyoxyalkylene ether polymer having a perfluoroalkyl ether group in the side chain.
As counter ions of the salts in these fluorosurfactants, Li, Na, K, NH ₄ , NH ₃ CH ₂ CH ₂ OH, NH ₂ (CH ₂ CH ₂ OH) ₂ , NH (CH ₂ CH ₂ OH) ₃ etc. are mentioned.

As said fluorosurfactant, what was synthesize | combined suitably may be used and a commercial item may be used.
Examples of commercially available products include Surflon S-111, S-112, S-113, S-121, S-131, S-132, S-141, and S-145 (all manufactured by Asahi Glass Co., Ltd.), Fullrad FC- 93, FC-95, FC-98, FC-129, FC-135, FC-170C, FC-430, FC-431 (all manufactured by Sumitomo 3M), MegaFuck F-470, F1405, F-474 ( All manufactured by Dainippon Ink and Chemicals), Zonyl TBS, FSP, FSA, FSN-100, FSN, FSO-100, FSO, FS-300, UR (all manufactured by DuPont), FT-110, FT-250 FT-251, FT-400S, FT-150, FT-400SW (all manufactured by Neos Co., Ltd.), PF-151N (manufactured by Omninova), and the like. It is. Among these, Zonyl FS-300, FSN, FSN-100, and FSO (manufactured by DuPont) are particularly preferable from the viewpoints of reliability and color development improvement.

(Other ingredients)
The other components are not particularly limited and may be appropriately selected as necessary. For example, resin emulsion, pH adjuster, antiseptic / antifungal agent, rust preventive, antioxidant, ultraviolet absorber, oxygen An absorber, a light stabilizer, etc. are mentioned.

(Resin emulsion)
The resin emulsion is obtained by dispersing resin fine particles in water as a continuous phase, and may contain a dispersant such as a surfactant as necessary.
The content of resin fine particles as the dispersed phase component (content of resin fine particles in the resin emulsion) is generally preferably 10 to 70% by mass. Further, the particle diameter of the resin fine particles is preferably 10 to 1000 nm, more preferably 20 to 300 nm, particularly considering use in an ink jet recording apparatus.

There is no restriction | limiting in particular as the resin fine particle component of the said dispersed phase, According to the objective, it can select suitably. Examples include acrylic resins, vinyl acetate resins, styrene resins, butadiene resins, styrene-butadiene resins, vinyl chloride resins, acrylic styrene resins, acrylic silicone resins, and among these, acrylic silicones A resin is particularly preferred.
As said resin emulsion, what was synthesize | combined suitably may be used and a commercial item may be used.

  Commercially available resin emulsions include, for example, Microgel E-1002, E-5002 (styrene-acrylic resin emulsion, manufactured by Nippon Paint Co., Ltd.), Boncoat 4001 (acrylic resin emulsion, manufactured by Dainippon Ink & Chemicals, Inc.) Boncoat 5454 (styrene-acrylic resin emulsion, manufactured by Dainippon Ink & Chemicals, Inc.), SAE-1014 (styrene-acrylic resin emulsion, manufactured by Nippon Zeon Co., Ltd.), Cybinol SK-200 (acrylic resin emulsion, Seiden) Chemical Co., Ltd.), Primal AC-22, AC-61 (acrylic resin emulsion, manufactured by Rohm and Haas), Nanoacryl SBCX-2821, 3689 (acrylic silicone resin emulsion, Toyo Ink Manufacturing Co., Ltd.) Company Ltd.), # 3070 (methyl methacrylate polymer resin emulsion, include Mikuni Color Co., Ltd.).

  The addition amount of the resin fine particle component in the resin emulsion in the ink is preferably 0.1 to 50% by mass, more preferably 0.5 to 20% by mass, and still more preferably 1 to 10% by mass. If the addition amount is less than 0.1% by mass, the effect of improving clogging resistance and ejection stability may not be sufficient, and if it exceeds 50% by mass, the storage stability of the ink may be reduced. There is.

  Examples of the antiseptic / antifungal agent include 1,2-benzisothiazolin-3-one, sodium dehydroacetate, sodium sorbate, sodium 2-pyridinethiol-1-oxide, sodium benzoate, sodium pentachlorophenol and the like. It is done.

The pH adjusting agent is not particularly limited as long as the pH can be adjusted to 7 or more without adversely affecting the ink, and any substance can be used according to the purpose.
Examples of the pH adjusting agent 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, Examples include quaternary phosphonium hydroxide, alkali metal carbonates such as lithium carbonate, sodium carbonate, and potassium carbonate.

  Examples of the rust preventive include acidic sulfite, sodium thiosulfate, ammonium thiodiglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, dicyclohexylammonium nitrite and the like.

  Examples of the antioxidant include phenol-based antioxidants (including hindered phenol-based antioxidants), amine-based antioxidants, sulfur-based antioxidants, phosphorus-based antioxidants, and the like.

  Examples of the phenolic antioxidants (including hindered phenolic antioxidants) include butylated hydroxyanisole, 2,6-di-tert-butyl-4-ethylphenol, stearyl-β- (3,5 -Di-tert-butyl-4-hydroxyphenyl) propionate, 2,2'-methylenebis (4-methyl-6-tert-butylphenol), 2,2'-methylenebis (4-ethyl-6-tert-butylphenol), 4,4′-Butylidenebis (3-methyl-6-tert-butylphenol), 3,9-bis [1,1-dimethyl-2- [β- (3-tert-butyl-4-hydroxy-5-methylphenyl) ) Propionyloxy] ethyl] 2,4,8,10-tetrixaspiro [5,5] undecane, 1,1,3-tris (2-methyl-) 4-hydroxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, tetrakis [methylene- 3- (3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) propionate] methane and the like.

  Examples of the amine-based antioxidant include phenyl-β-naphthylamine, α-naphthylamine, N, N′-di-sec-butyl-p-phenylenediamine, phenothiazine, N, N′-diphenyl-p-phenylenediamine. 2,6-di-tert-butyl-p-cresol, 2,6-di-tert-butylphenol, 2,4-dimethyl-6-tert-butyl-phenol, butylhydroxyanisole, 2,2′-methylenebis ( 4-methyl-6-tert-butylphenol), 4,4′-butylidenebis (3-methyl-6-tert-butylphenol), 4,4′-thiobis (3-methyl-6-tert-butylphenol), tetrakis [methylene -3 (3,5-di-tert-butyl-4-dihydroxyphenyl) propionate] meta 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane and the like.

  Examples of the sulfur-based antioxidant include dilauryl 3,3′-thiodipropionate, distearyl thiodipropionate, lauryl stearyl thiodipropionate, dimyristyl 3,3′-thiodipropionate, distearyl β. , β′-thiodipropionate, 2-mercaptobenzimidazole, dilauryl sulfide and the like.

  Examples of the phosphorus antioxidant include triphenyl phosphite, octadecyl phosphite, triisodecyl phosphite, trilauryl trithiophosphite, and trinonylphenyl phosphite.

  Examples of the ultraviolet absorber include a benzophenone ultraviolet absorber, a benzotriazole ultraviolet absorber, a salicylate ultraviolet absorber, a cyanoacrylate ultraviolet absorber, and a nickel complex ultraviolet absorber.

  Examples of the benzophenone-based ultraviolet absorber include 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-n-dodecyloxybenzophenone, 2,4-dihydroxybenzophenone, and 2-hydroxy-4-methoxybenzophenone. 2,2 ′, 4,4′-tetrahydroxybenzophenone and the like.

  Examples of the benzotriazole ultraviolet absorber include 2- (2′-hydroxy-5′-tert-octylphenyl) benzotriazole, 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-4′-octoxyphenyl) benzotriazole, 2- (2′-hydroxy-3′-tert-butyl-5′-methylphenyl) -5-chlorobenzotriazole and the like.

  Examples of the salicylate-based ultraviolet absorber include phenyl salicylate, p-tert-butylphenyl salicylate, p-octylphenyl salicylate, and the like.

  Examples of the cyanoacrylate ultraviolet absorber include ethyl-2-cyano-3,3′-diphenyl acrylate, methyl-2-cyano-3-methyl-3- (p-methoxyphenyl) acrylate, and butyl-2- And cyano-3-methyl-3- (p-methoxyphenyl) acrylate.

  Examples of the nickel complex-based ultraviolet absorber include nickel bis (octylphenyl) sulfide, 2,2′-thiobis (4-tert-octylferrate) -n-butylamine nickel (II), and 2,2′-thiobis. (4-tert-octylferrate) -2-ethylhexylamine nickel (II), 2,2′-thiobis (4-tert-octylferrate) triethanolamine nickel (II) and the like.

  The ink used in the ink jet recording apparatus of the present invention described above includes at least water, a colorant, and a wetting agent, and if necessary, a penetrating agent, a surfactant, and, if necessary, other components dispersed in an aqueous medium. Or it melt | dissolves and can also manufacture by stirring and mixing as needed. The dispersion can be performed by, for example, a sand mill, a homogenizer, a ball mill, a paint shaker, an ultrasonic disperser, and the like. be able to.

The viscosity of the ink is preferably 1 cps or more and 30 cps or less at 25 ° C., more preferably 2 to 20 cps. If the viscosity exceeds 20 cps, it may be difficult to ensure ejection stability.
The pH of the ink is preferably 7-10.

  There is no restriction | limiting in particular as coloring of the said ink, According to the objective, it can select suitably, Yellow, magenta, cyan, black etc. are mentioned. When recording is performed using an ink set in which two or more of these colorings are used in combination, a multicolor image can be formed. When recording is performed using an ink set in which all colors are combined, a full color image is formed. be able to.

  Hereinafter, the present invention will be described with reference to specific examples, but the present invention is not limited to these examples.

(Preparation Example 1)
-Preparation of copper phthalocyanine pigment-containing polymer fine particle dispersion-
After sufficiently replacing the inside of the 1 L flask equipped with a mechanical stirrer, thermometer, nitrogen gas introduction tube, reflux tube, and dropping funnel with nitrogen gas, 11.2 g of styrene, 2.8 g of acrylic acid, 12.0 g of lauryl methacrylate Then, 4.0 g of polyethylene glycol methacrylate, 4.0 g of styrene macromer (manufactured by Toa Gosei Co., Ltd., trade name: AS-6) and 0.4 g of mercaptoethanol were charged and heated to 65 ° C. Next, 100.8 g of styrene, 25.2 g of acrylic acid, 108.0 g of lauryl methacrylate, 36.0 g of polyethylene glycol methacrylate, 60.0 g of hydroxyethyl methacrylate, styrene macromer (trade name: AS-6, manufactured by Toagosei Co., Ltd.) A mixed solution of 36.0 g, mercaptoethanol 3.6 g, azobisdimethylvaleronitrile 2.4 g, and methyl ethyl ketone 18 g was dropped into the flask over 2.5 hours.
After completion of dropping, a mixed solution of 0.8 g of azobisdimethylvaleronitrile and 18 g of methyl ethyl ketone was dropped into the flask over 0.5 hours. After aging at 65 ° C. for 1 hour, 0.8 g of azobisdimethylvaleronitrile was added and further aging was performed for 1 hour. After completion of the reaction, 364 g of methyl ethyl ketone was added to the flask to obtain 800 g of a polymer solution having a concentration of 50% by mass. Next, a part of the polymer solution was dried and measured by gel permeation chromatography (standard: polystyrene, solvent: tetrahydrofuran). The weight average molecular weight (Mw) was 15,000.

Next, 28 g of the obtained polymer solution, 26 g of copper phthalocyanine pigment, 13.6 g of 1 mol / L potassium hydroxide aqueous solution, 20 g of methyl ethyl ketone, and 30 g of ion-exchanged water were sufficiently stirred. Thereafter, the mixture was kneaded 20 times using a three-roll mill (manufactured by Noritake Company, trade name: NR-84A). The obtained paste was put into 200 g of ion-exchanged water, and after sufficiently stirring, methyl ethyl ketone and water were distilled off using an evaporator to obtain 160 g of a blue polymer fine particle dispersion having a solid content of 20.0% by mass. .
About the obtained polymer microparticles | fine-particles, the average particle diameter (D50%) measured with the particle size distribution analyzer (Microtrac UPA, Nikkiso Co., Ltd.) was 93 nm.

(Preparation Example 2)
-Preparation of dimethylquinacridone pigment-containing polymer fine particle dispersion-
In Preparation Example 1, the copper phthalocyanine pigment was changed to C.I. I. A red-purple polymer fine particle dispersion was prepared in the same manner as in Preparation Example 1, except that the pigment red 122 was used.
About the obtained polymer microparticles | fine-particles, the average particle diameter (D50%) measured with the particle size distribution analyzer (Microtrac UPA, Nikkiso Co., Ltd.) was 127 nm.

(Preparation Example 3)
-Preparation of monoazo yellow pigment-containing polymer fine particle dispersion-
In Preparation Example 1, the copper phthalocyanine pigment was changed to C.I. I. A yellow polymer fine particle dispersion was prepared in the same manner as in Preparation Example 1, except that the pigment yellow 74 was changed.
About the obtained polymer microparticles | fine-particles, the average particle diameter (D50%) measured with the particle size distribution analyzer (Microtrac UPA, Nikkiso Co., Ltd.) was 76 nm.

(Preparation Example 4)
-Preparation of carbon black dispersion treated with sulfonating agent-
150 g of commercially available carbon black pigment (manufactured by Degussa, “Printex # 85”) was mixed well into 400 ml of sulfolane, finely dispersed with a bead mill, 15 g of amidosulfuric acid was added, and the mixture was stirred at 140 to 150 ° C. for 10 hours. The obtained slurry was put into 1000 ml of ion-exchanged water, and a surface-treated carbon black wet cake was obtained with a centrifuge at 12,000 rpm. The obtained carbon black wet cake is redispersed in 2,000 ml of ion exchange water, adjusted to pH with lithium hydroxide, desalted and concentrated with an ultrafiltration membrane, and a carbon black dispersion having a pigment concentration of 10% by mass. And filtering with a nylon filter having an average pore diameter of 1 μm to obtain a carbon black dispersion.
About the obtained carbon black dispersion, the average particle diameter (D50%) measured with the particle size distribution analyzer (Microtrac UPA, Nikkiso Co., Ltd.) was 80 nm.

(Production Example 1)
-Production of cyan ink-
Copper phthalocyanine pigment-containing polymer fine particle dispersion 20.0% by mass of Preparation Example 1, 3-methyl-1,3-butanediol 23.0% by mass, glycerin 8.0% by mass, 2-ethyl-1,3-hexane 2.0% by mass of diol, 2.5% by mass of FS-300 (manufactured by DuPont) as a fluorosurfactant, 0.2% by mass of Proxel LV (manufactured by Avecia) as an antiseptic / antifungal agent, 2-amino Appropriate amounts of 2-ethyl-1,3-propanediol 0.5% by mass and ion-exchanged water were added to obtain 100% by mass, followed by filtration through a membrane filter having an average pore size of 0.8 μm. A cyan ink was prepared as described above.

(Production Example 2)
-Magenta ink production-
Dimethylquinacridone pigment-containing polymer fine particle dispersion 20.0% by mass of Preparation Example 2, 3-methyl-1,3-butanediol 22.5% by mass, glycerin 9.0% by mass, 2-ethyl-1,3-hexane Diol 2.0% by mass, FS-300 (manufactured by DuPont) as a fluorosurfactant 2.5% by mass, Proxel LV (manufactured by Avecia) 0.2% by mass as antiseptic / antifungal agent, 1-amino An appropriate amount of -2,3-propanediol 0.5% by weight and ion-exchanged water was added to make 100% by mass, followed by filtration through a membrane filter having an average pore size of 0.8 μm. A magenta ink was prepared as described above.

(Production Example 3)
-Preparation of yellow ink-
Monoazo yellow pigment-containing polymer fine particle dispersion of Preparation Example 2 20.0% by mass, 3-methyl-1,3-butanediol 24.5% by mass, glycerin 8.0% by mass, 2-ethyl-1,3-hexane 2.0% by mass of diol, 2.5% by mass of FS-300 (manufactured by DuPont) as a fluorosurfactant, 0.2% by mass of Proxel LV (manufactured by Avecia) as an antiseptic / antifungal agent, 2-amino Appropriate amounts of 2-methyl-1,3-propanediol 0.5% by mass and ion exchange water were added to make 100% by mass, followed by filtration through a membrane filter having an average pore size of 0.8 μm. Thus, a yellow ink was prepared.

(Production Example 4)
-Preparation of black ink-
Carbon black dispersion of Preparation Example 4 20.0% by mass, 2-methyl-1,3-butanediol 22.5% by mass, glycerin 7.5% by mass, 2-pyrrolidone 2.0% by mass, 2-ethyl- 2.0 mass% of 1,3-hexanediol, 2.5 mass% of FS-300 (manufactured by DuPont) as a fluorosurfactant, 0.2 mass of Proxel LV (manufactured by Avecia) as an antiseptic and fungicidal agent %, 0.2 mass% of choline, and appropriate amounts of ion-exchanged water were added to make 100 mass%, followed by filtration with a membrane filter having an average pore diameter of 0.8 μm. A black ink was prepared as described above.

(Production Example 5)
-Production of cyan ink-
Copper phthalocyanine pigment-containing polymer fine particle dispersion 20.0% by mass of Preparation Example 1, 3-methyl-1,3-butanediol 23.0% by mass, glycerin 8.0% by mass, 2-ethyl-1,3-hexane Diol 2.0% by mass, Proxel LV (manufactured by Avecia) 0.2% by mass, 2-amino-2-ethyl-1,3-propanediol 0.5% by mass, and ion-exchanged water Was added to make 100% by mass, and then filtered through a membrane filter having an average pore size of 0.8 μm. A cyan ink was prepared as described above.

(Production Example 6)
-Magenta ink production-
Dimethylquinacridone pigment-containing polymer fine particle dispersion 20.0% by mass of Preparation Example 2, 3-methyl-1,3-butanediol 22.5% by mass, glycerin 9.0% by mass, 2-ethyl-1,3-hexane Diol 2.0% by mass, Proxel LV (manufactured by Avecia) 0.2% by mass, 2-amino-2-ethyl-1,3-propanediol 0.5% by mass, and ion-exchanged water Was added to make 100% by mass, and then filtered through a membrane filter having an average pore size of 0.8 μm. A magenta ink was prepared as described above.

(Production Example 7)
-Preparation of yellow ink-
Monoazo yellow pigment-containing polymer fine particle dispersion of Preparation Example 2 20.0% by mass, 3-methyl-1,3-butanediol 24.5% by mass, glycerin 8.0% by mass, 2-ethyl-1,3-hexane Diol 2.0% by mass, Proxel LV (manufactured by Avecia) 0.2% by mass, 2-amino-2-ethyl-1,3-propanediol 0.5% by mass, and ion-exchanged water Was added to make 100% by mass, and then filtered through a membrane filter having an average pore size of 0.8 μm. Thus, a yellow ink was prepared.

(Production Example 8)
-Preparation of black ink-
Carbon black dispersion of Preparation Example 4 20.0% by mass, 2-methyl-1,3-butanediol 22.5% by mass, glycerin 7.5% by mass, 2-pyrrolidone 2.0% by mass, 2-ethyl- 2.0 mass% of 1,3-hexanediol, 0.2 mass% of proxel LV (manufactured by Avecia) as an antiseptic and fungicidal agent, and 0.5 mass of 2-amino-2-ethyl-1,3-propanediol % And ion exchange water were added in an appropriate amount to 100 mass%, and then filtered through a membrane filter having an average pore diameter of 0.8 μm. Thus, a black ink was prepared.

  Next, the surface tension and viscosity of each ink of Production Examples 1 to 8 produced as described above were measured as follows. The results are shown in Table 1.

<Measurement of viscosity>
The viscosity was measured at 25 ° C. using a R-500 viscometer (manufactured by Toki Sangyo Co., Ltd.) under conditions of cone 1 ° 34 ′ × R24, 60 rpm, 3 minutes later.

<Measurement of surface tension>
The surface tension is a static surface tension measured at 25 ° C. using a platinum plate using a surface tension measuring device (CBVP-Z, manufactured by Kyowa Interface Science Co., Ltd.).

Next, a recording medium (recording medium) for printing using the ink is prepared.
The recording medium is composed of a support and a coating layer.

-Production of support-
A 0.3 mass% slurry having the following composition was made with a long paper machine to prepare a support having a basis weight of 79 g / m ² . In addition, in the size press process of the papermaking process, the oxidized starch aqueous solution was applied so that the solid content was 1.0 g / m ² per side.
-Hardwood bleached kraft pulp (LBKP) ... 80 parts by mass-Softwood bleached kraft pulp (NBKP) ... 20 parts by weight-Light calcium carbonate (trade name: TP-121, manufactured by Okutama Kogyo Co., Ltd.) ... 10 Part by mass-Aluminum sulfate-1.0 part by mass-Amphoteric starch (trade name: Cato3210, manufactured by NSC Japan)-1.0 part by weight-Neutral rosin sizing agent (trade name: NeuSize M-10) , Manufactured by Harima Chemicals Co., Ltd.) ... 0.3 parts by mass Yield improver (trade name: NR-11LS, manufactured by Hymo Co., Ltd.) ... 0.02 parts by mass

  Next, the following recording medium (recording medium) is obtained by forming a coating layer on the support.

(Production Example 9)
-Production of recording medium 1-
70 parts by mass of clay having a particle diameter of 2 μm or less as a pigment of 97% by mass, 30 parts by mass of heavy calcium carbonate having an average particle diameter of 1.1 μm, and styrene having a glass transition temperature (Tg) of −5 ° C. as an adhesive -Add 8 parts by weight of butadiene copolymer emulsion, 1 part by weight of phosphate esterified starch, and 0.5 parts by weight of calcium stearate as an auxiliary agent, and then add water to obtain a coating solution having a solid content concentration of 60% by weight. Prepared.
The obtained coating solution was applied to both sides using a blade coater so that the solid content per side of the prepared support was 8 g / m ² , dried with hot air, and then subjected to a step super calender treatment. As a result, “Recording medium 1” was produced.

(Production Example 10)
-Production of recording medium 2-
70 parts by mass of clay having a particle diameter of 2 μm or less as a pigment of 97% by mass, 30 parts by mass of heavy calcium carbonate having an average particle diameter of 1.1 μm, and styrene having a glass transition temperature (Tg) of −5 ° C. as an adhesive -Addition of 7 parts by mass of butadiene copolymer emulsion, 0.7 parts by mass of phosphoric acid esterified starch, 0.5 parts by mass of calcium stearate as an auxiliary agent, and further water to add a coating solution having a solid content concentration of 60% by mass Was prepared.
The obtained coating solution is coated on both sides using a blade coater so that the solid content per side is 8 g / m ² on the prepared support, dried with hot air, and then subjected to a step super calender treatment. "Recording medium 2" was produced.

Example 1
-Ink set, recording media, and image recording-
“Ink set 1” consisting of black ink of Production Example 4, yellow ink of Production Example 3, magenta ink of Production Example 2 and cyan ink of Production Example 1 was prepared by a conventional method.
Using the obtained ink set 1 and the recording medium 1, an image forming apparatus according to the present invention having 300 dpi, nozzle resolution 384, and nozzles (changed description for replenishment) was used, and the image resolution was 600 dpi, Printing was performed with a maximum ink droplet of 18 pl. The amount of secondary color was regulated to 140% and the amount of adhesion was regulated, and solid images and characters were printed to obtain an image print.

(Comparative Example 1)
-Ink set, recording media, and image recording-
Example 1 was the same as Example 1 except that a commercially available offset coated paper (trade name: Aurora coat, basis weight = 104.7 g / m ² , manufactured by Nippon Paper Industries Co., Ltd.) was used as the recording medium. Then, printing was carried out and an image print was obtained.

(Comparative Example 2)
-Ink set, recording media, and image recording-
In Example 1, printing was carried out in the same manner as in Example 1 except that a commercially available ink-jet mat coated paper (trade name; Superfine exclusive paper, manufactured by Seiko Epson Corporation) was used as the recording medium. I got an image print.

(Example 2)
-Ink set, recording media, and image recording-
In Example 1, except that the recording medium 2 was used as a recording medium, printing was performed in the same manner as in Example 1 to obtain an image print.

(Example 3)
-Ink set, recording media, and image recording-
In Example 1, a gravure coated paper (trade name; space DX, basis weight = 56 g / m ² , manufactured by Nippon Paper Industries Co., Ltd.) (hereinafter referred to as “recording medium 3”) was used as the recording medium. Except for the above, printing was performed in the same manner as in Example 1 to obtain an image print.

(Comparative Example 3)
-Ink set, recording media, and image recording-
In Example 1, the recording medium described above was used as the recording medium, using the ink set 2 composed of the black ink of Production Example 8, the yellow ink of Production Example 7, the magenta ink of Production Example 6, and the cyan ink of Production Example 5. Except that 1 was used, printing was performed in the same manner as in Example 1 to obtain an image print.

(Comparative Example 4)
-Ink set, recording media, and image recording-
In Example 1, the ink set 2 was used in place of the ink set 1, and a commercially available offset coated paper (trade name: Aurora coat, basis weight = 104.7 g / m ² , manufactured by Nippon Paper Industries Co., Ltd.) was used as the recording medium. ) Was used, and printing was carried out in the same manner as in Example 1 to obtain an image print.

(Comparative Example 5)
-Ink set, recording media, and image recording-
In Example 1, the ink set 2 was used in place of the ink set 1, and a commercially available inkjet mat coated paper (trade name; Superfine exclusive paper, manufactured by Seiko Epson Corporation) was used as a recording medium. In the same manner as in Example 1, printing was performed to obtain an image print.

(Comparative Example 6)
-Ink set, recording media, and image recording-
In Example 1, printing was performed in the same manner as in Example 1 except that the ink set 2 was used instead of the ink set 1 and the recording medium 2 was used as a recording medium. Got.

Next, with respect to the recording medium 1, the recording medium 2, the recording medium 3, and the recording media used in Comparative Examples 4 to 5, pure water using a dynamic scanning absorptiometer and production are as follows. The transfer amount of the cyan ink of Example 1 was measured. The results are shown in Table 2 below.
In addition, for the recording medium 1, the recording medium 2, and the recording media used in Comparative Examples 4 to 5, the amount of cyan ink transferred in Production Example 5 was measured by a dynamic scanning absorption meter as follows. did. The results are shown in Table 3 below.
<Measurement of transfer amount of pure water and cyan ink by dynamic scanning absorption meter>
For each recording medium, the amount of pure water or cyan ink transferred was measured using a dynamic scanning absorption meter (K350 series D type, manufactured by Kyowa Seiko Co., Ltd.). The transfer amount at the contact time of 100 ms and the contact time of 400 ms was determined by interpolation from the measured value of the transfer amount at the contact time adjacent to each contact time.

  Next, for the image prints of Examples 1 to 3 and Comparative Examples 1 to 6 obtained as described above, beading, bleeding, spur marks, and glossiness were evaluated as follows. The results are shown in Table 4 below.

<Beading>
The degree of beading of the green solid image portion of each image print was visually observed and evaluated according to the following criteria.
〔Evaluation criteria〕
A: Uniform printing without beading.
○: Slight beading is observed.
(Triangle | delta): Generation | occurrence | production of beading is recognized clearly.
×: Significant beading is observed.

<Evaluation of bleed>
The degree of bleed of black letters in the yellow of each image print was visually observed and evaluated according to the following criteria.
〔Evaluation criteria〕
A: Clear printing without bleeding.
○: Slight bleeding is observed.
Δ: Bleed is clearly observed.
X: The blur has occurred so that the outline of the character is not clear.

<Evaluation of spur marks>
The degree of spurs on each image print was visually observed and evaluated according to the following criteria.
〔Evaluation criteria〕
A: Not recognized at all.
○: Slightly recognized.
Δ: Spur marks are observed.
X: Spur marks are clearly recognized.

<Evaluation of glossiness>
The degree of glossiness of the image portion of each image print was visually observed and evaluated according to the following criteria.
〔Evaluation criteria〕
A: High gloss.
○: Glossy.
X: A glossiness is not recognized.

As is clear from the results shown in Tables 1 to 4, ink containing at least water, a colorant, and a wetting agent, and having a surface tension at 25 ° C. of 20 to 35 mN / m, and dynamic scanning The amount of ink transferred to the recording medium at a contact time of 100 ms measured with a liquid absorption meter is 4 to 15 ml / m ² , and the amount of ink transferred to the recording medium at a contact time of 400 ms is 7 to 20 ml / m ^2. In the ink media sets of Examples 1 to 3 combined with the recording media, the beading, bleed, spur marks, and glossiness were all evaluated as compared with the ink media sets of Comparative Examples 1 to 6. Good results were obtained for.

1 is a schematic configuration diagram of an example of an ink jet recording apparatus of the present invention. 1 is a schematic configuration diagram of a serial type ink jet recording apparatus. 1 is a schematic configuration diagram of a line-type ink jet recording apparatus. The schematic sectional drawing of an example of a conveyance belt is shown. A printing process diagram when the head resolution is 600 dpi and the standard paper feed direction resolution is 600 dpi is shown. (A), (b) The printing process figure which changed the paper feed speed is shown. (A), (b) The printing process figure which changed the ejection period of the ink is shown. The printing process figure which adjusted the printing dot position using the some head is shown. The printing process figure which performs multipass printing is shown. The printing process figure which changed the resolution of the subscanning direction is shown. The printing process diagram using a highly absorbent paper is shown. The printing process figure which improved the resolution using the paper with high absorptivity is shown. A state diagram in which beading has occurred is shown. The printing process figure which reduced the amount of ink droplets and made the dot diameter small is shown. A state diagram in which white spots are generated using a sheet having low absorbency is shown. A state diagram in which ink droplets are adjusted to avoid white spots is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Apparatus main body 2 Image formation part 3 Recording medium (printing paper)
4 Feeding tray 5 Conveying mechanism 6 Discharging tray 7 Duplex unit 11, 12 Guide shaft 13 Carriage 14 Recording head 15 Ink cartridge 21 Feeding roller (half-moon roller)
23 guide portion 23a guide surface 23b guide surface 24 transport roller 25 pressure roller 26 guide member 27 guide member 28 pressing roller 31 drive roller 32 driven roller 33 transport belt 34 charging roller 35 guide roller 38 paper discharge roller

Claims (26)

A head unit equipped with a nozzle that ejects ink for printing onto the surface of the printing paper is mounted,
A line-type inkjet recording apparatus that performs printing with ink droplets ejected from the head unit over the entire printing paper by transporting the printing paper with the head unit corresponding to the width of the printing paper fixed. And
The printing paper feeding direction is controlled in accordance with the ink absorbency of the printing paper, and the image data is converted and printed in accordance with the resolution in the printing paper feeding direction. Line-type inkjet recording apparatus.   2. The line type ink jet recording apparatus according to claim 1, further comprising means for controlling a resolution in the printing paper feeding direction by changing a feeding speed of the printing paper.   2. The line type ink jet recording apparatus according to claim 1, further comprising means for controlling a resolution in the printing paper feeding direction by changing a period of ejecting ink from the nozzles. A plurality of nozzles for jetting ink of the same color are arranged in parallel;
2. The line-type ink jet recording according to claim 1, further comprising means for controlling the resolution in the printing paper feeding direction by selecting an ejection port for ejecting ink and adjusting the position of the printing dot. apparatus.   2. The line-type ink jet recording according to claim 1, further comprising means for controlling the resolution in the printing paper feeding direction by hitting dots between dots hit earlier in multi-pass printing. apparatus. 5. The apparatus according to claim 1, further comprising means for setting the resolution in the print paper feeding direction to n times the head resolution (1.0 ≦ n ≦ X / a) according to the absorbability of the print paper. The line type ink jet recording apparatus according to any one of 1 to 5.
However, X is 2400 dpi and a is the head resolution. The ink transfer amount at a contact time of 100 ms measured at 23 ° C. and 50% RH is ² to 40 ml / m ² , and the ink transfer amount at a contact time of 400 ms is 3 to 3. In the case of printing on a printing paper of 50 ml / m ² , there is provided means for setting the resolution in the paper feeding direction to m times the head resolution (1.0 ≦ m ≦ X / 2a). The line type ink jet recording apparatus according to any one of claims 1 to 6.
However, X is 2400 dpi and a is the head resolution.   The apparatus according to any one of claims 1 to 7, further comprising means for changing the resolution in the paper feeding direction and the resolution in a direction orthogonal to the paper feeding direction by performing interlaced printing. The line-type inkjet recording apparatus described.   The line-type ink jet according to any one of claims 1 to 8, further comprising means for controlling an ink droplet amount to be ejected so that an ink adhesion amount per unit area is constant. Recording device.   The line according to any one of claims 1 to 9, further comprising means for detecting a degree of ink dot spread on the printing paper and adjusting an ink adhesion amount per unit area. Type ink jet recording apparatus. A head unit equipped with a nozzle that ejects ink for printing onto the surface of the printing paper is mounted,
A serial type ink jet recording apparatus that scans the head unit perpendicularly to a feeding direction of the printing paper and performs recording with ink droplets ejected from the head unit,
When image formation is performed only by one scan of the head unit, the resolution in the main scanning direction is controlled according to the absorbency of the printing paper, and the image data is converted according to the resolution in the main scanning direction. A serial type ink jet recording apparatus comprising a means for printing.   12. The serial type ink jet recording apparatus according to claim 11, further comprising means for changing the moving speed of the head unit to control the resolution in the main scanning direction.   12. The serial type ink jet recording apparatus according to claim 11, further comprising means for controlling a resolution in the main scanning direction by changing a period of ejecting ink from the nozzles. A plurality of nozzles for jetting ink of the same color are arranged in parallel;
12. The serial type ink jet recording according to claim 11, further comprising means for controlling the resolution in the main scanning direction by selecting an ejection port for ejecting ink and adjusting the position of the printing dot. apparatus.   12. The serial type ink jet according to claim 11, further comprising means for controlling the resolution in the main scanning direction by striking dots between dots previously ejected in multi-pass printing. Recording device. 12. The apparatus according to claim 11, further comprising means for setting the resolution in the main scanning direction to n times the head resolution (1.0 ≦ n ≦ X / a) according to the absorbability of the printing paper. 16. The serial type inkjet recording apparatus according to any one of items 1 to 15.
However, X is 2400 dpi and a is the head resolution. The ink transfer amount at a contact time of 100 ms measured at 23 ° C. and 50% RH is ² to 40 ml / m ² , and the ink transfer amount at a contact time of 400 ms is 3 to 3. In the case of printing on a printing paper of 50 ml / m ² , there is provided means for setting the resolution in the main scanning direction to m times the head resolution (1.0 ≦ m ≦ X / 2a). The serial type inkjet recording apparatus according to any one of claims 11 to 16.
However, X is 2400 dpi and a is the head resolution.   18. The serial type ink jet according to claim 11, further comprising means for changing the resolution in the main scanning direction and the sub-scanning direction by performing interlaced printing. Recording device.   The serial type inkjet according to any one of claims 11 to 18, further comprising means for controlling an ink droplet amount to be ejected so that an ink adhesion amount per unit area is constant. Recording device.   20. The serial according to claim 11, further comprising means for detecting a degree of ink dot spread on the printing paper and adjusting an ink adhesion amount per unit area. Type ink jet recording apparatus. A head unit having nozzles for ejecting ink to be printed on the surface of the printing paper is mounted, and the printing paper is transported in a state where the head unit corresponding to the width of the printing paper is fixed, whereby the entire printing paper A printing method using a line-type inkjet recording apparatus that performs printing with ink droplets ejected from the head unit.
A printing method comprising: controlling resolution in a printing paper feed direction according to the absorbency of the printing paper; converting image data according to the resolution in the printing paper feed direction; A head unit having nozzles for ejecting ink for printing onto the surface of the printing paper is mounted, the head unit is scanned perpendicularly to the feeding direction of the printing paper, and recording is performed by ink droplets ejected from the head unit. A printing method using a serial type ink jet recording apparatus,
When image formation is performed only by one scan of the head unit, the resolution in the main scanning direction is controlled according to the absorbency of the printing paper, and the image data is converted according to the resolution in the main scanning direction. A printing method characterized by printing.   A control program causing an inkjet recording apparatus to execute the printing method according to claim 21 or 22. An ink used for the ink jet recording apparatus according to any one of claims 1 to 20,
An ink comprising at least water, a colorant, and a wetting agent.   The ink according to claim 24, wherein the surface tension at 25 ° C is 15 to 40 mN / m.   The ink according to claim 24 or 25, further comprising a fluorine-based surfactant.

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