JP2006256126A - Inkjet recorder, method of inkjet recording, and recording material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recorder that can retain equal amounts of deposited ink droplets per a unit area in different colors even when ink sets by which the weights of ink droplets each ejected by one shot are different from each other are used, and can maintain high printing quality. <P>SOLUTION: This inkjet recorder comprises an ink set having different n ("n" is an integer of two or greater number) kinds of inks. A ratio of the minimum weight of ink to be ejected to the maximum weight of ink to be ejected is not greater than 0.6. The inkjet recorder satisfies the expression: 0.8≤Iwi×Ri<SP>2</SP>/Iw1×R1<SP>2</SP>≤1.2 by each "i" ("i" is an integer number from 1 to n) with the proviso that each of the weights of ink to be ejected is represented by Iw1, Iw2,..., Iwi,..., and Iwn (Iw1 is the minimum weight of ink) and each of the nozzle resolutions of an ejection nozzle group assigned to each ink is represented by R1, R2,..., Ri,..., and Rn. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  In the ink jet recording apparatus having an ink set composed of a plurality of colors, the present invention can ensure the same amount of shot per unit area even when using ink sets having different weights of ink droplets ejected in one shot. The present invention relates to an ink jet recording apparatus that can maintain high print quality.

  2. Description of the Related Art Conventionally, various ink jet recording apparatuses with good print quality have been developed. For example, JP-A-8-336979 discloses a color ink jet recording apparatus that performs color recording by discharging a plurality of colors of ink, and uses a recording head of a slow fixing ink or a lower frequency depending on viscosity, droplet ejection volume, or the like. A color ink jet recording apparatus that suppresses bleeding and has good print quality by increasing the number of nozzles of an ink recording head that requires ink ejection from the number of nozzles of other recording heads that eject ink is disclosed. (Patent Document 1).

However, even if the number of nozzles is increased as in such an ink jet recording apparatus, the amount of driving per unit area does not increase. Further, this publication does not have a numerical description of the relationship between the ink physical properties and the nozzle resolution of the ink jet recording apparatus, and is less effective. In the conventional recording apparatus, there is a problem that the printing amount per unit area varies among the colors and the printing quality cannot be ensured because the weight of the ink droplets ejected in one shot in each ink of the ink set is different.
JP-A-8-336979

  Therefore, the present invention provides an ink jet recording apparatus that can secure the amount of shot per unit area equivalent to each color and maintain high print quality even when ink sets having different weights of ink droplets ejected in one shot are used. The purpose is to do.

As a result of earnest research, the present inventor has obtained the following findings.
When the ink weight per unit area is greatly different for each color, the uniformity of solid filling in the recording medium differs for each color, which may contribute to deterioration of image quality.
The ink weight per unit area, which is good for solid filling in the recording medium and reduces the set-off, is the super-penetrating ink (the permeation time to the coated surface when the coating amount is 1 mg / cm ² ). In the case of an ink) of less than 1 second, it is about 0.6 to 1.2 mg / cm ² . This corresponds to about 30-60 ng / (360 dpi) ² .
When the difference in ink weight per unit area of each color is large and the ink weight per unit area of a certain color is larger than about 1.2 mg / cm ² , color bleeding to other adjacent colors occurs. (Color bleed) and can contribute to image quality degradation.

And when this inventor further researched based on said each knowledge, following 1. The object was achieved by providing the invention.
1. In an ink jet recording apparatus comprising an ink set composed of n types of different inks (n is an integer of n ≧ 2),
The ejected ink weight (the weight of the ink droplet ejected in one shot) is different for each ink,
The ratio of the minimum discharge ink weight / the maximum discharge ink weight in the ink set is 0.6 or less,
Iw1, Iw2, ..., Iwi, ..., Iwn (Iw1 is the minimum discharge ink weight), respectively,
When the nozzle resolution of the ejection nozzle group assigned to each ink is R1, R2,..., Ri,.
For all i (i is an arbitrary integer from 1 to n)
0.8 ≦ Iwi × Ri ² / Iw1 × R1 ² ≦ 1.2
An ink jet recording apparatus, wherein:

The present invention also provides the following 2. ~ 7. Each invention is provided.
2. 2. The ink jet recording according to 1 above, wherein all the inks in the ink set are penetrable inks having a permeation time of less than 1 second when the amount of ink applied to the recording medium is 1 mg / cm ^2. apparatus.

  3. 3. The ink jet recording apparatus according to 1 or 2, wherein the concentration of the colorant contained in the ink that gives the minimum discharge ink weight is the highest among all the inks.

  4). 4. The ink jet recording apparatus according to any one of 1 to 3, wherein the ink that gives the minimum discharge ink weight is black ink.

  5. 5. The ink jet recording apparatus as described in 4 above, wherein the black ink is a pigment ink.

6). In an ink jet recording method for recording using an ink set composed of n types of inks (n is an integer of n ≧ 2),
The ejected ink weight (the weight of the ink droplet ejected in one shot) is different for each ink,
The ratio of the minimum discharge ink weight / the maximum discharge ink weight in the ink set is 0.6 or less,
Iw1, Iw2, ..., Iwi, ..., Iwn (Iw1 is the minimum discharge ink weight), respectively,
When the nozzle resolution of the discharge nozzle group assigned to each ink is R1, R2,..., Ri,.
For all i (i is an arbitrary integer from 1 to n)
0.8 ≦ Iwi × Ri ² / Iw1 × R1 ² ≦ 1.2
An ink jet recording method, wherein recording is performed so that

  7). A recorded matter in which an image is formed on a recording medium by the inkjet recording apparatus according to 1 or the inkjet recording method according to 6.

According to the present invention, there is provided an ink jet recording apparatus capable of ensuring a high printing quality while ensuring a driving amount per unit area equivalent to each color even when ink sets having different weights of ink droplets ejected in one shot are used. Is done.
Further, according to the present invention, an ink jet recording method capable of ensuring a high printing quality by ensuring a shot amount per unit area equivalent to each color even when ink sets having different weights of ink droplets ejected in one shot are used. In addition, a recorded matter with high print quality is provided.

  The ink jet recording apparatus according to the present invention will be described below based on preferred embodiments thereof.

As described above, the ink jet recording apparatus of the present invention is an ink jet recording apparatus including ink sets composed of n different types of inks (n is an integer of n ≧ 2). The weight of the ink droplets is different for each ink, and the ratio of the minimum discharge ink weight / the maximum discharge ink weight in the ink set is 0.6 or less. The discharge ink weight of each ink in the ink set is Iw1, Iw2, ..., Iwi, ..., Iwn (Iw1 is the minimum discharge ink weight), and the nozzle resolution of the discharge nozzle group assigned to each ink is R1, R2, ..., Ri, ..., respectively. When Rn is set, the following expression is established for all i (i is an arbitrary integer from 1 to n).
0.8 ≦ Iwi × Ri ² / Iw1 × R1 ² ≦ 1.2
Here, R1 represents the nozzle resolution of the discharge nozzle assigned to the ink with the minimum discharge ink weight Iw1. The nozzle resolutions R1, R2,..., Ri,..., And Rn are the discharge nozzles corresponding to the inks of the discharge ink weights Iw1, Iw2,. Represents the nozzle resolution.

  Since the ink jet recording apparatus of the present invention has the above-described configuration, even when ink sets having different weights of ink droplets ejected in one shot (hereinafter referred to as “ejection ink weight”) are used, the unit areas equivalent to the respective colors are used. The amount of per shot can be secured and high print quality can be maintained. That is, this recording apparatus is an O.D. D. The value, solid filling and set-off prevention properties are improved in a well-balanced manner.

  To briefly explain the concept of the present invention, consider the case where the relationship between the weight of ejected ink and the nozzle resolution is the following numerical example. In each case, the number of shots required to form one dot is 1. In the following, Bk means black ink and Col means color ink.

(Case 1) Bk nozzle resolution = 720 dpi, Col nozzle resolution = 360 pdi,
Bk ejected ink weight = 11 ng, Col ejected ink weight = 45 ng
(Case 2) Bk nozzle resolution = 600 dpi, Col nozzle resolution = 600 pdi,
Bk ejected ink weight = 11 ng, Col ejected ink weight = 45 ng
(Case 3) Bk nozzle resolution = 720 dpi, Col nozzle resolution = 360 pdi,
Bk ejected ink weight = 40 ng, Col ejected ink weight = 40 ng
(Case 4) Bk nozzle resolution = 600 dpi, Col nozzle resolution = 600 pdi,
Bk ejected ink weight = 40 ng, Col ejected ink weight = 40 ng

Here, the application range of the present invention is such that the minimum discharge ink weight / the maximum discharge ink weight is 0.6 or less, and P ≦ Iwi × Ri ² / Iw1 × R1 ² , 0.8 ≦ P ≦ 1.2 is there.
In the case of (Case 1), the weight ratio of ejected ink is 0.24 and P = 1.02, which is within the applicable range of the present invention.
In this case, the weight of ink ejected in the range of 1 cm ² is as follows.
Bk; 11 × 10 ⁻⁶ /(2.53/720) ² = 0.89 mg / cm ² ,
Col; 45 × 10 ⁻⁶ /(2.53/360) ² = 0.91 mg / cm ²
Bk and Col are well balanced, and solid filling is possible in the same way. In addition, the ink weight per unit area is also in an appropriate range of 1 mg / cm ^2, and deterioration due to settling, color bleeding, etc. does not occur.

In the case of (Case 2), the weight ratio of ejected ink is 0.24 and P = 4.09, which is outside the scope of the present invention.
In this case, the weight of ink ejected in the range of 1 cm ² is as follows.
Bk; 11 × 10 ⁻⁶ /(2.53/600) ² = 0.62 mg / cm ²
Col: 45 × 10 ⁻⁶ /(2.53/600) ² = 2.53 mg / cm ²
Since the balance between Bk and Col is poor and the value of Col is large, there is a case where the image quality is deteriorated due to the see-through of Col ink and the seepage of Col to Bk.

In the case of (Case 3), the weight ratio of ejected ink is 1.00 and P = 0.25, which is outside the scope of the present invention.
In this case, the weight of ink ejected in the range of 1 cm ² is as follows.
Bk; 40 × 10 ⁻⁶ /(2.53/720) ² = 3.23 mg / cm ²
Col: 40 × 10 ⁻⁶ /(2.53/360) ² = 0.81 mg / cm ²
Since the balance between Bk and Col is poor and the value of Bk is large, image quality deterioration may occur due to Bk ink set-off and bleeding of Bk into Col.

In (Case 4), the weight ratio of ejected ink is 1.00 and P = 1.00, which is outside the scope of the present invention.
In this case, the weight of ink ejected in the range of 1 cm ² is as follows.
Bk; 40 × 10 ⁻⁶ /(2.53/600) ² = 2.24 mg / cm ² ,
Col; 40 × 10 ⁻⁶ /(2.53/600) ² = 2.24 mg / cm ²
Bk and Col are well balanced, and solid filling is possible in the same way. However, the ink weight per unit area is large, and deterioration due to settling may occur.

  The ink that can be used in the ink jet recording apparatus of the present invention is ejected as droplets from a printer head of an ink jet printer in order to record and form images such as characters and figures on a recording medium such as paper by a so-called ink jet recording method. It is used as a recording liquid.

In the present invention, the ink to be used is not particularly limited as long as two or more different ink sets are used and the condition of the above formula is satisfied. There are two or more types of ink in the ink set, and 2 to 8 types are particularly preferable. The ink composition is the same as the ink composition used for normal ink for ink jet recording. In particular, all inks in the ink set have an ink application amount of 1 mg / cm ² on the recording medium. It is preferable that the ink has such a permeability that the permeation time is less than 1 second (hereinafter also referred to as a super permeation type ink).
Here, when the coating amount is 1 mg / cm ² , the ink whose permeation time is less than 1 second is specifically, for example, when 50 ng of ink is applied to an area of 360 dpi (dots / inch) × 360 dpi In addition, it refers to ink that takes less than 1 second until it becomes smudged with ink even when the printing surface is touched.

  This super-penetration type ink has improved penetration by adding a water-soluble organic solvent or a penetration enhancer such as a surfactant that reduces the surface tension of the aqueous solution to improve the wettability of the recording medium. It is.

  Examples of water-soluble organic solvents include lower alcohols such as ethanol and propanol, cellosolves such as ethylene glycol monomethyl ether and ethylene glycol monoethyl ether, carbitols such as diethylene glycol monomethyl ether and diethylene glycol monoethyl ether, and 1,2-hexane. Examples include 1,2-alkanediols such as diol and 1,2-octanediol. Among these, glycol butyl ether-based aqueous organic solvents such as diethylene glycol monobutyl ether and triethylene glycol monobutyl ether are particularly preferable in terms of providing excellent penetrability.

  In addition, surfactants include anionic surfactants such as fatty acid salts and alkyl sulfate esters, nonionic surfactants such as polyoxyethylene alkyl ether and polyoxyethylene phenyl ether, cationic surfactants, and zwitterionic surfactants. A surfactant or the like can be used. Among these, nonionic surfactants are particularly preferred because of their low foaming properties, and acetylene glycol-based nonionic surfactants are particularly preferred in terms of providing excellent penetrability.

  These penetration enhancers are preferably added by adjusting the surface tension of the ink at 20 ° C. to 45 mN / m or less, preferably 40 mN / m or less, either alone or in combination with a water-soluble organic solvent. .

  The ratio of the minimum discharge ink weight / the maximum discharge ink weight in the ink set is 0.6 or less, preferably 0.2 to 0.6.

  It is preferable that the concentration of the colorant contained in the ink that gives the minimum discharge ink weight in the ink set is the highest among all the inks because the balance between the high OD value and the print quality of the ink can be maintained. .

  Black ink is the ink that gives the minimum discharge ink weight in the ink set, but black ink is the majority of printing in offices and homes, so it occurs especially for black ink quality This is preferable in that the present invention can effectively meet a high demand for improvement. In this case, the black ink is a pigment ink using a pigment as a colorant, and in addition to being able to obtain higher print quality on general-purpose paper such as plain paper and recycled paper, it has high water resistance and weather resistance. This is more preferable in that a recorded matter can be obtained.

  The discharge ink weight is not particularly limited, but the discharge ink weight Iw1 of the ink that gives the minimum discharge ink weight is preferably 2 to 15 ng, and the discharge ink weights Iw2, Iw3,. Preferably it is 20-60 ng.

  The nozzle resolution of the discharge nozzle group assigned to the ink is not particularly limited, but the nozzle resolution R1 of the ink that gives the minimum discharge ink weight is preferably 600 to 1500 dpi, and the other nozzle resolutions R2, R3,. , Rn is preferably 90 to 500 dpi.

  The ink jet recording apparatus of the present invention can be suitably applied to a high speed printer such as a line head printer or an ink jet page printer.

The present invention also provides the following recording method. As for a suitable aspect of the recording method, the description of the recording apparatus described above is applied as appropriate.
In an ink jet recording method for recording using an ink set composed of n types of inks (n is an integer of n ≧ 2),
The ejected ink weight (the weight of the ink droplet ejected in one shot) is different for each ink,
The ratio of the minimum discharge ink weight / the maximum discharge ink weight in the ink set is 0.6 or less,
Iw1, Iw2, ..., Iwi, ..., Iwn (Iw1 is the minimum discharge ink weight), respectively,
When the nozzle resolution of the discharge nozzle group assigned to each ink is R1, R2,..., Ri,.
For all i (i is an arbitrary integer from 1 to n)
0.8 ≦ Iwi × Ri ² / Iw1 × R1 ² ≦ 1.2
An ink jet recording method, wherein recording is performed so that

  According to the present recording method, even when ink sets having different weights of ink droplets ejected in one shot are used, it is possible to secure a printing amount per unit area equivalent to each color and maintain high print quality. That is, this recording method is an O.D. D. The value, solid filling and set-off prevention properties are improved in a well-balanced manner.

  Further, the present invention can provide a recorded matter in which an image is formed on a recording medium by the above-described inkjet recording apparatus or the above-described inkjet recording method, and the recorded matter has high print quality. . That is, this recorded matter is O.D. D. Value, solid filling and set-off prevention properties are provided in a well-balanced manner.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not restrict | limited at all by this Example.

  Each color ink (inks 1 to 9) having the colorant type, the colorant concentration and the discharge ink weight shown in Table 1 was used in the examples. These inks contain 3 parts by weight of triethylene glycol mono-n-butyl ether and 0.5 parts by weight of surfactant Olphine E1010 (trade name, manufactured by Nissin Chemical Industry Co., Ltd.) with respect to the total amount of ink. This is a super-penetration type ink as defined in the present invention.

  Using these inks, one of the ink sets A to E shown in Table 2 and one of the heads A to D having the head configuration shown in Table 2 are displayed. 3 or the combination shown in Table 4 was prepared.

  About these inkjet recording devices, the printed matter was formed on the recording medium, and evaluations 1-3 were performed according to the following criteria. The results are shown in Table 5.

Evaluation 1: O.D. of ink giving minimum ejected ink weight. D. Value (average value of 5 papers)
Judgment A 1.40 or more Judgment B 1.25 or more and less than 1.40 Judgment C 1.10 or more and less than 1.25 Judgment D less than 1.10

Evaluation 2: Solid filling Judgment A In all five evaluation papers, there is no white streak in the solid printing part. Judgment B State in which white streaks are visually observed in the solid printing part in two or less paper types. In the above paper type, the white streaks are visually observed in the solid print portion. Determination D The white streaks are visually observed in the solid print portion in all five evaluation papers.

Evaluation 3: Set-off when the printed material is viewed from the back Judgment A A state in which there is almost no set-off in all five evaluation papers Judgment B State in which the set-off is visually observed in two or less paper types Judgment C 4 paper In the following paper types, the set-off is visually observed Judgment D The set-off is visually observed in all five evaluation papers

The evaluation was performed using the following five types of plain paper / recycled paper.
Xerox 4024, Xerox P, Hmmermill copyplus (neutral paper), EPP (acidic paper), Xerox R (recycled paper)

  The present invention provides an ink jet recording apparatus and an ink jet recording method capable of ensuring a high printing quality while ensuring a driving amount per unit area equivalent to each color even when ink sets having different weights of ink droplets ejected in one shot are used. In addition, it has industrial applicability as a recorded matter with high print quality.

Claims (7)

In an ink jet recording apparatus comprising an ink set composed of n types of different inks (n is an integer of n ≧ 2),
The ejected ink weight (the weight of the ink droplet ejected in one shot) is different for each ink,
The ratio of the minimum discharge ink weight / the maximum discharge ink weight in the ink set is 0.6 or less,
Iw1, Iw2, ..., Iwi, ..., Iwn (Iw1 is the minimum discharge ink weight), respectively,
When the nozzle resolution of the discharge nozzle group assigned to each ink is R1, R2,..., Ri,.
For all i (i is an arbitrary integer from 1 to n)
0.8 ≦ Iwi × Ri ² / Iw1 × R1 ² ≦ 1.2
An ink jet recording apparatus, wherein: 2. The inkjet according to claim 1, wherein all inks in the ink set are inks having permeability such that a penetration time is less than 1 second when the amount of ink applied to the recording medium is 1 mg / cm ^2. Recording device.   The ink jet recording apparatus according to claim 1, wherein the concentration of the colorant contained in the ink that gives the minimum discharge ink weight is the highest among all the inks.   The ink jet recording apparatus according to claim 1, wherein the ink that gives the minimum discharge ink weight is a black ink.   The ink jet recording apparatus according to claim 4, wherein the black ink is a pigment ink. In an ink jet recording method for recording using an ink set composed of n types of inks (n is an integer of n ≧ 2),
The ejected ink weight (the weight of the ink droplet ejected in one shot) is different for each ink,
The ratio of the minimum discharge ink weight / the maximum discharge ink weight in the ink set is 0.6 or less,
Iw1, Iw2, ..., Iwi, ..., Iwn (Iw1 is the minimum discharge ink weight), respectively,
When the nozzle resolution of the discharge nozzle group assigned to each ink is R1, R2,..., Ri,.
For all i (i is an arbitrary integer from 1 to n)
0.8 ≦ Iwi × Ri ² / Iw1 × R1 ² ≦ 1.2
An ink jet recording method, wherein recording is performed so that   A recorded matter in which an image is formed on a recording medium by the ink jet recording apparatus according to claim 1 or the ink jet recording method according to claim 6.