KR0138802B1 - Color ink-jet recording method - Google Patents

Abstract

In the present invention, a recording method of ejecting a drop of two or more inks so as to be adjacent to or superimposed on a recording medium according to a pulse signal, wherein the ink contains 1.0 to 20.0% by weight of a nonionic surfactant, There is provided a color ink jet recording method, wherein the ejection amount of the ink is 10 to 70 pl, and the feathering rate A represented by the following formula I is 2.5 to 3.5.

Formula I

A = B / C

(Wherein B is the diameter of the dots formed on the plain sheet (µm) and C is the diameter of the ejected droplets (µm))

Description

How to record color ink jet

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a diagram showing an example of a dot pattern of a dichroic ink.

Fig. 2 is a diagram showing another dot pattern example by dichroic ink.

3 is a horizontal sectional view of the head portion of the ink jet recording apparatus of the present invention.

4 is a horizontal sectional view of the head portion of the ink jet recording apparatus of the present invention.

5 is a perspective view of a head portion of the ink jet recording apparatus of the present invention.

6 is a perspective view of the ink jet recording apparatus of the present invention.

Figure 7 is a longitudinal sectional view of the ink cartridge of the present invention.

8 is a perspective view of the recording unit of the present invention.

Fig. 9 is a perspective view of a recording head in which a plurality of recording heads are used as an example of the present invention.

10 is a perspective view of another recording head used in the present invention.

* Description of the symbols for the main parts of the drawings *

13 head 15 heat head

16: protective layer 17-1, 17-2: aluminum electrode

18: heat generating layer 19: heat storage layer

20: substrate 21: ink

22: eruption orifice 23: meniscus

24: ink drop 25: recording medium

27 glass plate 28 heat generating head

40: ink container 42: rubber plug

44: ink absorbing member 45: ink cartridge

52: paper transport roller 53: paper release roller

61: blade 62: cap

63: absorbing member 64: ejection recovery section

65: recording head 66: carriage

67: guide rod 68: motor

69: belt 70: recording unit

71: head 72: atmospheric communication opening

[Purpose of invention]

[Technical Field to which the Invention belongs and Prior Art in the Field]

The present invention relates to an ink jet recording method for forming excellent color recording on plain paper such as fine paper, heavy paper, bond paper, and copy paper.

The ink jet recording method uses various ink (recording liquid) ejection methods, for example, electrostatic suction method, a method of imparting mechanical vibration or displacement to the ink using piezoelectric elements, a method of applying thermal energy to the ink, and the like. A small drop is generated and made to fly, and a part or all of them are attached to a recording material by paper or the like to record. There is no noise, and attention has been paid as a recording method capable of performing a high speed factor and a kali factor.

Particularly in recent monochromatic ink jet printers, by increasing the density of the printhead and improving the ink performance, it is generally used in ordinary paper such as commercially available high-quality paper, heavy paper, and general PPC (electrophotographic recording paper). Good printing also becomes possible, and there exists a tendency to become increasingly popular by the compactness of a printer main body, low cost, and the like.

By the way, in the color ink jet printer, it is a fact that high quality images cannot be obtained unless the coated paper developed for ink jet recording is used.

[Technical problem to be achieved]

The reason for this is that the following problems are not solved.

(1) In the color boundary on a plain paper, since dichroic inks mix, the image deteriorates.

(2) In particular, the deterioration of the image in the boundary region with the mixed color portion in which dichroic ink is superimposed is remarkable.

(3) Due to the poor fixability of the ink of the mixed part in which the ink input amount is large, contamination occurs due to contact with the recording apparatus or adheres to the hand.

These reasons are because, when the dichroic ink is thrown in adjacent or overlapping, the next ink is introduced before the first ink is sufficiently fixed.

As the ink of the penetration drying type which makes the fixing time extremely short, for example, as disclosed in Japanese Patent Application Laid-Open No. 55-27546, an amount of the surfactant added is added more than before, and the cellulose such as paper which the surfactant has has been added. There is a technical means of penetrating paper and making it appear seemingly dry in an instant. On the other hand, there is a printing method in consideration of the time for the ink attached on the paper to fully settle, for example, a feeding method for lengthening the time difference between adjacent ink drops as possible.

However, by simply adding a large amount of surfactant, even if the effect of improving the fixing property is recognized, the prevention of mixing of the dichroic inks in the color boundary is insufficient, and ink penetrating into the back direction of the paper is insufficient. Because of its large size, since the color concentration on the paper is lowered or the fiber layer on the paper surface is not dyed uniformly, there is a problem such that density spots occur in the front surface (ie, solid) printing region and image quality deteriorates.

In addition, the printing method taking into account the time for sufficiently fixing the ink has a drawback that the paper feed speed must be lowered in any case, even if there are various feeding methods, and of course, the time until the end of printing becomes longer. The high speed factor, which is an advantage of the jet recording method, cannot be realized.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and its object is to produce a high quality color image without mixing of dichroic inks in a color boundary at a general ordinary position, and with a good color density, and without density stains. The present invention provides a method for recording a color ink jet.

The above object is achieved by the following invention. That is, the present invention is a color ink jet recording method for ejecting two or more ink droplets adjacent or superimposed on a recording medium according to a pulse signal, wherein the ink contains 1.0 to 20.0 wt% of a nonionic surfactant, The ejection amount of ink per one pulse is 10 to 70 pl, and the feathering rate (A) represented by the following formula (I) is in the range of 2.5 to 3.5.

Formula I

A = B / C

(Where B is the diameter of the dot formed on the plain sheet (µm) and C is the diameter of the ejected ink droplet (µm))

The present inventors first paid attention to the following as conditions necessary for forming a high quality color image on a plain paper.

That is, in the dichroic ink input method as shown in Fig. 1, even if the input time difference between adjacent inks is short, mixing of the dichroic ink in the color boundary is preferable because it is relatively difficult to occur, but is surrounded by dots. When the center part becomes blank, which causes a decrease in color density, and when these ink drops deviate even a little from the normal position to which the ink droplets are to be adhered, the inconvenience that the area of the blank part increases increases.

Therefore, if the input method as shown in Fig. 2, that is, the following formula (II) is satisfied, the above problem is considerably alleviated, and a good image can be obtained.

Formula II

×10³ B≥1 / DX

× 10 ³

(Wherein B is the diameter of a dot formed on a normal sheet (µm) and D is the recording density (dot / min)).

However, when such a dosing method is performed, as indicated by the oblique line, the mixing portion of the dichroic ink is inevitably generated, and the dichroic ink is easily mixed in the color boundary.

Thus, the inventors of the present invention provide a method of satisfying the above formula (II), and a method of preventing mixing of dichroic ink in a color boundary while maintaining good character quality on the premise of injecting ink droplets. As a result of earnestly examining, it was found that the above-mentioned problem was solved by adjusting and printing the patterning rate A represented by the formula I to be in the range of 2.5 to 3.5 on the normal ground.

That is, when the patterning rate is 2.5 or less, the spread of ink droplets adhering on the paper surface is small and the thickness of the ink layer is not thin. Therefore, when it is added under the conditions shown in Fig. 2, the dichroism in the color boundary When mixing of the ink occurs and the patterning rate is 3.5 or more, the ink droplets are spread too much on the contrary, and the sharpness of the edges of the dots is lost.

As a means for adjusting a patterning rate in the range of 2.5-3.5, it is a thing to adjust a patterning rate by containing 1-20 weight% of nonionic surfactant in ink, Preferably 3-10 weight%. When the amount of the nonionic surfactant to be used is less than 1% by weight, the patterning rate is 2.5 or less, and mixing of dichroic ink in the color boundary occurs, and when the amount of the nonionic surfactant is 20% by weight or more, the patterning rate is 3.5 or more. It becomes the inconvenience that deterioration of character quality occurs.

In addition, another reason for using a nonionic surfactant here is based on the following 2nd knowledge. That is, by simply using a large amount of surfactant, it is possible to reduce the color density due to the excessive penetration of ink droplets into the paper, and to deteriorate the character quality and to uneven dyeing of the fiber layer on the paper surface. Although the problem of the generation of the density spots in the solid part region occurs, the type of surfactant used is a nonionic surfactant, and the ejection amount according to one pulse of the ink droplet containing 1 to 20% by weight of this is 1. When printing in the range of 10 to 70 pl per nozzle, preferably 20 to 50 pl, it was found that high quality good color recording as described above can be realized. Here, since the nonionic surfactant does not have a selective affinity for the fiber layer on the surface of the paper, it is possible to obtain a uniform dyeing effect, and does not generate concentration stains. The ink of the color recording method of this chestnut contains a large amount of a surfactant, and when the ejection amount corresponding to one pulse of the ink droplet is 70 pl or more per nozzle, the ink amount is absorbed into the three oil layers on the paper surface. As the ink capacity exceeds the allowable ink capacity, ink penetrates into the hole layer further below the fiber layer due to the penetrating force of the surfactant, which results in a decrease in color density or an irregular ink outflow. Since deterioration of quality occurs, the ink ejection amount must be 10 to 70 pl / pulse.

As the nonionic surfactant used in the present invention, polyoxyethylene alkyl ether, polyoxyethylene phenyl ether, polyoxyethylene-polyoxypropylene glycol, polyoxyethylene-polyoxypropylene alkyl ether, acetylene glycol-polyethylene oxide adduct And nonylphenyl ether-EO adducts, ethylene oxide-propylene oxide copolymers (EO-PO copolymers), and ethylene glycol-polyethylene oxide adducts are preferable, and these are represented by the following structural formulas. Particularly preferred are acetylene glycol polyethylene oxide adducts (acetylene glycol EO adducts).

(Wherein m + n = 10)

As the water-soluble organic solvent used in the present invention other than the nonionic surfactant, amides such as dimethylformamide and dimethylacetamide; Ketones such as acetone; Ethers such as tetrahydrofuran and dioxane; Polyalkylene glycols such as polyethylene glycol and polypropylene glycol; Alkylene glycols having 2 to 6 carbon atoms such as ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, thiodiglycol, and hexylene glycol; glycerin; 1,2,6-hexanetriol; Lower alkyl ethers of polyhydric alcohols such as ethylene glycol methyl (or ethyl) ether, diethylene glycol methyl (or ethyl) ether and triethylene glycol monomethyl (or ethyl) ether; N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, triethanolamine, sulfolane, dimethyl sulfoxide and the like. Antiblocking agents include urea and its derivatives, sulfonamides and the like.

Dyes used in the present invention include direct dyes, acid dyes, reactive dyes, disperse dyes, bat dyes, etc., the dye content is determined depending on the type of liquid medium components and the predetermined characteristics of the ink, but in general It is 0.5-15 weight% with respect to, and 1-7 weight% is more preferable.

Although the main component of the ink of this invention was mentioned above, the objective of this invention can also be achieved by mixing another additive. As an additive, Viscosity modifiers, such as a polyvinyl alcohol, a cellulose, a water-soluble resin; PH adjusters such as diethanolamine, triethanolamine, and buffer solutions; A bactericide etc. are mentioned, It is preferable to add resistivity modifiers, such as lithium chloride, ammonium chloride, and sodium chloride, to the chargeable ink used for inkjet recording which charges ink droplets.

The recording method of the present invention is particularly suitable for ink jet recording in which ink droplets are ejected by the action of thermal energy, but can also be used for other ink jet recording methods.

Hereinafter, a recording apparatus suitable for forming ink droplets by thermal energy and performing recording of the present invention will be described. The present invention is suitable for a recording system in which a recording signal is applied to the recording ink of the recording head, and ink droplets are ejected by the action of the generated thermal energy. The configuration of the recording head, which is the main part of the apparatus, is shown in Figs.

The head 13 is constituted by bonding a glass, ceramic or plastic plate having an ink flow path to the heat generating head 15 (the head is shown in the drawing, but the present invention is not limited thereto). It has a high heat irradiation property such as the heat generating resistance layer 18, the heat storage layer 19, aluminum, etc. which are formed of the protective layer 16 formed of silicon oxide, etc., the aluminum electrodes 17-1, 17-2, nichrome, etc. It consists of a substrate 20.

The ink 21 reaches the jet orifice 22 and forms the meniscus 23 under the action of the pressure P not shown.

When an electric signal is popular with the electrodes 17-1 and 17-2, the area indicated by n on the heat generating head 15 generates rapid heat in the ink portion in contact with these to form bubbles. The pressure generated by the bubbles pushes out the meniscus 23 to eject the ink 21 from the orifice 22 in the form of ink droplets 24, and the ink droplets are ejected to the recording medium 25. FIG. 5 shows a plurality of recording heads constructed by arranging a plurality of heads shown in FIG. 3 in parallel. The recording head is manufactured by coupling a glass plate 27 having a plurality of flow paths to the heat generating head 28 as shown in FIG. .

3 is a sectional view of the head 13 along the ink flow path, and FIG. 4 is a sectional view of the head at line A-B in FIG.

6 shows an example of a head-mounted ink jet recording apparatus.

In Fig. 6, as the wiping member, the blade 61 is held at one end by the blade holding member to form a fixed end in a cantilever shape. The blade 61 is positioned at a position adjacent to the recording area of the recording head, and moves in a direction perpendicular to the moving direction of the recording head to come into contact with the ejection nozzle face to cover the nozzle. Further, an ink absorbing member 63 is provided at a position adjacent to the blade 61, and is held so as to be pushed into the moving passage of the recording head in the same manner as the blade 61. The blade 61, the cap 62, and the absorbing member 63 constitute a jet recovery section 64, and the blade 61 and the absorbing member 63 remove water, dust, and the like from the ink jet nozzle surface. .

The recording head 65 has ejection energy generating means for ejecting, and records by ejecting ink to the recording medium opposite to the ejection nozzle surface. In addition, a carriage 66 is provided to support and move the recording head 65. The carriage 66 is slidably coupled by the guide rod 67. A portion of the carriage 66 is connected to the belt 69 driven by the motor 68 and is movable along the guide rod 67 to the recording area adjacent to the recording head 65.

The paper conveying unit 51 for transporting the recording medium and the paper conveying roller 52 driven by a motor (not shown) transport the recording medium to a position opposite to the ejection nozzle face of the recording head, and as the recording proceeds. The recording medium is ejected to the paper ejecting portion provided with the paper ejecting roller 53.

In the above configuration, when the recording head 65 has completed recording or returns to the home position at another timing, the cap 62 of the ejection recovery section 64 is positioned out of the movement of the recording head 65 so that the blade 61 Is pushed into the moving path, the ejection nozzle face of the recording head 65 is wiped. The cap 62 is moved so as to be pushed toward the movement path of the recording head when it comes into contact with the ejection nozzle face of the capping recording head.

When the recording head 65 moves from the home position to the recording start position, the cap 62 and the blade 61 are present at the same position as in the wiping time, so that the ejection nozzle face is moved to this movement. Wiped by

The recording head moves to the home position not only at the ejection recovery at the recording stage but also at a predetermined interval during the movement for recording in the recording area, and the wiping is performed by this movement.

Fig. 7 shows an example of an ink cartridge containing ink supplied through an ink supply member such as a tube, and the ink container portion 40, for example, an ink bag, contains ink to be supplied and a rubber plug at the tip. 42). By inserting a needle (not shown) into the plug 42, the ink of the ink bag 40 can be supplied, and the ink absorbing member 44 absorbs the ink.

The ink container portion preferably has a liquid contact surface made of polyolefin, in particular polyethylene.

The ink jet recording apparatus used in the present invention is not limited to the above having the head and the ink cartridge separately, so that an integrated type may be used as shown in FIG.

In Fig. 8, the recording unit 70 has an ink container portion such as an ink absorbing member, and ink in the ink absorbing member is ejected from the head 70 having a plurality of orifices. The ink absorbing member may be made of polyurethane or the like material. In addition, an atmospheric communication opening 72 is provided to communicate the inside of the cartridge with the outdoors, and a recording unit 71 is used instead of the recording head shown in Fig. 6, which is easily detachable with respect to the carriage 66.

Although an ink jet recording apparatus for ejecting ink droplets by applying thermal energy to the ink is exemplified, the present invention can also be used for other ink jet recording apparatuses such as piezoelectric forms using piezoelectric elements.

In order to perform recording according to the present invention, a recording apparatus, for example, one in which four recording heads shown in Fig. 5 are arranged in parallel on the carriage is used. Fig. 9 shows an example of the apparatus, in which the recording heads 81, 82, 83, and 84 are recording heads which eject yellow, magenta, cyan and black recording ink, respectively, which are provided in the recording apparatus. Each color ink is ejected in accordance with the recording signal. Although the apparatus of FIG. 9 uses four recording heads, the present invention is not limited to this, and one recording head may be configured to eject all of yellow, magenta, cyan and black as shown in FIG.

Hereinafter, the present invention will be described in detail through examples and comparative examples. In addition, unless otherwise indicated, parts and% are weight part and weight%, and ethylene oxide adduct is abbreviated as EO adduct.

In addition, 100 parts of ink are prepared, respectively using the amounts (parts) of dyes and liquid media shown below in Examples and Comparative Examples.

[Examples 1-8, Comparative Examples 1-4]

A color ink jet recording apparatus is used which has four heads of the same recording density for yellow, magenta, cyan and black colors, and generates ink droplets by recording the ink by applying thermal energy to the ink of the recording head. In addition, three types of multi-nozzle-on-demand heads having a recording density of 300 dpi (11.8 dots / mm), 360 dpi (14.2 dots / mm), and 400 dpi (15.7 dots / mm) are used.

Color inks (yellow, magenta, cyan and black) for each example are prepared by sufficiently stirring the composition shown below and pressure filtration through a fluorine filter (0.22 micrometer pore diameter, manufactured by Sumitomo Electric Industries, Ltd.).

(dyes)

Black: C.I. Food Black Part 22

The following dyes A1.2 parts

The following dyes B0.7 part

Yellow: C.I. Direct Yellow Part 862.5

Cyan: C.I. Direct Blue 1993.5

Magenta: C3.5 part

(Liquid medium)

Thiodiglycol7.5parts

Urea Part 7.5

Glycerin7.5part

Surfactants (shown in Table 1)

Pure balance

With a recording device having a head of the recording density shown in Table 1, the ejection amounts shown in Table 1 were placed on commercially available copy paper (Canon NP dry SK and Xerox 4024) and ordinary bond paper (Plover bond paper sheet PB). Record and evaluate the records as follows.

The printed dot diameter and the patterning rate derived from the dot diameter are shown in Table 1, and the evaluation results are shown in Table 2.

Records are made under an environment at a temperature of 25 ± 2 ° C. and a humidity of 50-70% RH, and after printing, the samples are left to stand for 1 day and then evaluated.

The dot diameter (B of Formula I) of this invention calculates | requires a dot area by performing the image processing of the dot printed by a CCD camera, and calculates this area in conversion to the diameter of an exact circle. The diameter of the ink droplets (C in formula I) is calculated from the following formula.

V = (4/3) π (C / 2) ³ × 10 ^-3

(V is the drop volume ejected per pulse (p1))

The evaluation items are as follows:

(1) bleeding:

Color samples are prepared by printing different colors adjacent to each other, and the occurrence of bleeding is evaluated based on the following criteria. The evaluation was performed in seven colors: black, yellow, cyan and magenta; This is done for red, green and blue obtained by dot dot superimposing two meals taken in yellow, cyan and magenta.

○: No bleeding is observed at all boundaries

(Triangle | delta): When a large amount of ink is apply | coated, bleeding is remarkable in red, green, and blue boundary.

×: bleeding is prominent at almost all boundaries

(2) color uniformity

Visually test the uniformity of the solid calendered section.

○: Solid calorie chain is completely uniform without irregularity

△: nonuniformity is remarkable in the part with high fiber density

X: Color nonuniformity is very remarkable

(3) Incidence rate of feathering

Three hundred dots are continuously printed on normal copy paper and bond paper so that the dots do not contact each other, and the dot ink is dried in air at room temperature for 24 hours. Irregular shapes and irregular feathering of dots are counted under a microscope, and evaluation is performed in% of the number of dots counted according to the following criteria.

◎: 10% or less,

○: 11-30%

△: 31-50%

×: 51% or more

(4) optical density

The optical density of the print is measured by MacBeth Refractodensitometer RD-915 (manufactured by MacBeth Co.). Average O.D. values for yellow, magenta, cyan and black are evaluated according to the following criteria.

○: 1.0 or more

△: 0.9 to 1.0

×: 0.9 or less

[Effects of the Invention]

As described above, according to the color ink jet recording method of the present invention, there is no mixing of the dichroic inks in the color boundary on ordinary plain papers, and also good character quality, color density, and density unevenness. High quality color images can be formed.

Claims (3)

A recording method for ejecting two or more drops of ink so as to adjoin or overlap on a recording medium according to a pulse signal, wherein the ink contains 1.0 to 20.0% by weight of a nonionic surfactant, and the ejection amount of ink per pulse 10 to 70 pl, and the feathering rate (A) represented by the following formula (I) is 2.5 to 3.5. Formula I A = B / C (Where B is the diameter of the dot formed on the plain sheet (µm) and C is the diameter of the ejected ink droplet (µm)) The nonionic surfactant according to claim 1, wherein the nonionic surfactant is polyoxyethylene alkyl ether, polyoxyethylene phenyl ether, polyoxyethylene-polyoxypropylene glycol, polyoxyethylene-polyoxypropylene alkyl ether, and acetylene glycol-polyethylene oxide addition. Color ink jet recording method characterized in that it contains at least one selected from the group consisting of water. 2. The color ink jet recording method according to claim 1, wherein the recording medium has fibers exposed on its surface.

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