JPH05320551A - Color ink for ink-jet printer - Google Patents

Abstract

PURPOSE:To obtain the subject ink, causing no difference in printing qualities with kinds of paper, no running at a dot boundary resulting from color blending of ink, no color unevenness, etc., comprising a specific pigment and resin component by dispersing the pigment into a nonaqueous solvent having dissolved the resin component. CONSTITUTION:In blending a resin component (e.g. acrylic acid ester copolymer resin or rosin-based resin) with yellowing pigment (e.g. monoazo pigment or disazo pigment), magenta coloring pigment (e.g. monoazo pigment or azo lake pigment), cyanic color showing pigment (e.g. disazo pigment or phthalocyanine pigment) and blackening pigment (e.g. aniline black pigment or carbon black), firstly dissolved in an nonaqueous solvent and preferably 1-30wt.% of the pigment resin component is dispersed into the solution to give the objective ink.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color ink for an ink jet printer which can be applied to a color ink jet recording apparatus for ejecting ink to form characters and images on a transfer medium such as recording paper.

[0002]

2. Description of the Related Art Conventionally, ink jet recording methods can be roughly classified into two types, a continuous type and an on-demand type. As a color ink used in such an ink jet system, an ink in which a dye is dissolved in water is predominant (hereinafter referred to as an aqueous ink). The water-based ink is currently used in which various water-soluble dyes are dissolved in water or a solvent composed of water and a water-soluble organic solvent, and various additives are added as necessary. The advantage of these ink jet recording is that the process is simple because it is direct recording. Since it is not an impact method, there is no noise, high-speed recording is possible, low running cost because plain paper can be used, high-resolution recording is possible because minute ink droplets are ejected. It has features and its future is drawing attention.

[0003]

However, the conventional ink jet recording type color printer has the following problems contrary to the above advantages. First, depending on the quality of the transferred paper, there are those that can obtain good printing quality to those that show extremely poor printing quality, and the printing quality greatly depends on the paper type. Secondly, ink bleeding occurs at the overlapping portions of dots of yellow (hereinafter referred to as Y), magenta (hereinafter referred to as M), cyan (hereinafter referred to as C), and black (hereinafter referred to as Bk). The resulting resolution is reduced. Thirdly, when dots are printed adjacent to each other, the inks are mixed to cause bleeding at dot boundaries, color unevenness, and color turbidity, resulting in deterioration of image quality. Fourthly, there is a problem that the printing speed cannot be increased because the drying speed on the recording paper is slow (the printing and recording portion is rubbed and smeared by a paper guide or the like immediately after printing).

For the purpose of solving this, Japanese Patent Laid-Open No. 03-142
In Japanese Laid-Open Patent Publication No. 252630/1990, a printing apparatus is divided into a line drawing mode and an image mode, the number of scannings on the same line of a carriage is set, and ink is dispersed according to the number of scannings. A digital color printer that does not overlap the Y, M, C dots and the Bk dots in one pixel is reported by image processing the color components per pixel of M, C, and Bk to reduce the amount of ink used. .. But,
In these recording methods, there is a cost increase due to the installation of a calculation system for image data processing, and the waiting time of the recording apparatus is long because the processing time is relatively long. Also, especially for one pixel B
When the amount of the color component of k becomes large, the problems 1 to 3 of the water-based ink described above occur, and a fundamental solution to the problem has not been achieved.

Therefore, the present invention has been made to solve the above problems, and the purpose of the present invention is, firstly, that there is no difference in print quality depending on the paper type, and secondly, Y, M, C, Ink bleeding does not occur in the area where the dots of each color of Bk overlap and the resolution does not decrease. Thirdly, when dots are printed adjacent to each other, the inks are mixed and the bleeding at the dot boundary, color unevenness, and color turbidity cause image quality deterioration. Fourthly, there is provided a color ink for an ink jet printer which does not cause a decrease and which has a fast drying speed on a recording paper and can increase a printing speed.

[0006]

A color ink for an ink jet printer of the present invention contains at least a pigment exhibiting yellow, magenta, cyan and black colors and a resin component, and the pigment is added to a non-aqueous solvent in which the resin component is dissolved. Is dispersed.

Acrylic ester copolymer resin, rosin resin, hydrogenated terpene resin, alkylphenol resin, aromatic oligomer resin, alicyclic saturated hydrocarbon, hydrogenated dicyclopentadiene, aliphatic hydrocarbon resin as the resin component. It is characterized by selecting from.

A pigment exhibiting a yellow color is a monoazo pigment,
Disazo pigment, azo lake pigment, condensed azo pigment, acidic dye lake pigment, basic dye lake pigment, anthraquinone pigment, isoindolinone pigment, quinophthalone pigment, isoindoline pigment, niloroso pigment, metal complex salt azomethine pigment, magenta color Pigments exhibiting a monoazo pigment, disazo pigment, azo lake pigment, condensed azo pigment,
Acid dye lake pigment, basic dye lake pigment, anthraquinone pigment, thioindigo pigment, perinone pigment, perylene pigment, quinacridone pigment, isoindolinone pigment,
Select from alizarin lake pigments, cyan pigments are selected from disazo pigments, phthalocyanine pigments, acid dye lake pigments, basic dye lake pigments, anthraquinone pigments, and alkali blue pigments, and black pigments are aniline black. It is characterized in that it is selected from pigments and carbon black.

[0009]

EXAMPLES Examples of the present invention will be described in detail below.

The following may be considered as the composition in the ink of the present invention.

Examples of a yellow color exhibiting a monoazo pigment are Fast Yellow G (Y-1), and Disazo pigments are Disazo Yellow AAA (Y-1).
2), azo lake pigments such as tartrazine yellow lake (Y-100), condensed azo pigments such as condensed azo yellow GR (Y-95), acidic dye lake pigments such as quinoline yellow lake (Y-115), basic dyes Lake pigments: Thioflavin lake (Y-1)
8), anthraquinone pigments are exemplified by flavantron yellow (Y-24), isoindolinone pigments are exemplified by isoindolinone yellow 3RLT (Y-110),
Quinophthalone pigments quinophthalone yellow (Y
-138), isoindoline pigments are exemplified by isoindoline yellow (Y-139), nitroso pigments are exemplified by nickel nitroso yellow (Y-153), metal complex salt azomethine pigments are exemplified by copper azomethine yellow (Y-1).
17) etc. are considered.

To give magenta color, monoazo pigments such as toluidine red (R-3), disazo pigments such as pyrazolone red B (R-38), and azo lake pigments such as lake red C (R-53:
1) and condensed azo pigments, for example, condensed azo red BR (R
-144), an acidic dye lake pigment, Phloxine B lake (R-174), a basic dye lake pigment, Rhodamine 6G 'lake (R-81), an anthraquinone pigment, dianthraquinonyl red (R-).
177), thioindigo pigments such as thioindigo bordeaux (R-88), perinone pigments such as perinone red (R-194), perylene pigments such as perylene scarlet (R-149), and quinacridone pigments such as quinacridone magenta (R-122). , Isoindolinone pigment, for example, Isoindolinone Red 2BL
T (R-180), alizarin lake pigment, and Madara lake (R-83) are considered as examples.

Examples of cyan pigments include disazo pigments such as dianisidine blue (B-25) and phthalocyanine pigments such as phthalocyanine blue (B-).
15), acid dye lake pigments such as peacock blue lake (B-24), basic dye lake pigments such as bicrothia pure blue BO lake (B-1), and anthraquinone pigments such as indanthrone blue (B).
-60) and alkali blue pigments, for example, alkali blue (V-5: 1) and the like are considered.

Examples of pigments exhibiting Bk color include aniline black pigments such as organic pigments such as Bk-1 (aniline black) and iron oxide pigments, and carbon blacks such as furnace black, lamp black, acetylene black and channel black. Can be considered.

The pigments that can be used in the present invention are illustrated, but the numbers in parentheses are C.I. I pigment number, for example, Y-1
Is C. I. Pigment Yellow 1 Similarly R
-81 is C.I. I. Pigment Red 81 and B-15 are C.I. I. Pigment Blue 1 and Bk-1 are C.I. Represents I Pigment Black 1.

Basically, it is preferable to use one kind of pigment for each color, but two kinds may be used in combination depending on the case. Further, the addition amount is 1 to 1 in the ink composition.
30 weight percent is preferred, and even more preferred is 3 to 12 weight percent. Furthermore, the average dispersed particle size of the pigment is 2
It is preferably 5 μm or less, more preferably 5 μm or less.

In the color ink for an ink jet printer of the present invention, a resin is dissolved for the purpose of imparting dispersion stability of a dispersed pigment, adjusting the viscosity of the ink, improving scratch resistance of a recorded matter after printing and recording. Specific examples of the resin component soluble in the non-polar insulating solvent include acrylic acid ester copolymer resin (exemplified by lauric acid methacrylate copolymer resin) and rosin resin (exemplified by tetrahydroxyabietic acid resin). , Hydrogenated terpene resins, alkylphenol resins, aromatic oligomer resins, alicyclic saturated hydrocarbons, hydrogenated dicyclopentadiene, aliphatic hydrocarbon resins and the like can be used.

The non-aqueous solvent that can be used in the present invention includes a non-polar insulating solvent such as an aliphatic hydrocarbon solvent, specifically, Isopar of Exxon Co., Soltor of Phillip Oil Co., Idemitsu Petrochemical Co. IP Solvent of Petroleum Naphtha is S.P. B. R. , Shelsol, Vegasol of Mobil Oil Co., and the like. The properties required for the nonpolar insulating solvent of the present invention are low toxicity, low flammability, and low odor.
These may be used in combination of two or more depending on the case.

Color inks for ink jet printers using the ink composition described above can be manufactured by a known method. As an example, after the resin is added and dissolved in a non-polar insulating solvent, the pigment is added and treated with a dispersing machine such as a ball mill, attritor, or sand mill to obtain a uniform dispersion system to obtain the ink for an inkjet printer of the present invention. Is the way. If necessary, after the ink is manufactured, a filter may be used to remove large particles and dust.

Table 1 shows ink compositions according to the examples of the present invention (Examples 1 to 32) and comparative examples (Examples 1 to 3).

[0021]

[Table 1]

The water-based ink compositions of Comparative Examples 1 to 4 shown in Table 1 are almost the same as those of commercially available water-based inks. Comparative Example 1 is yellow, Comparative Example 2 is magenta, Comparative Example 3 is cyan, and Comparative Example. Reference numeral 4 is an ink exhibiting a black color. After producing the ink, confirmation evaluation of print quality due to difference in paper type (hereinafter referred to as paper type correspondence rate evaluation), bleeding evaluation in a portion where dots are overlapped (hereinafter referred to as dot overlay printing evaluation),
Evaluation items shown below regarding color turbidity or color unevenness on the color boundary surface when dots are printed adjacent to each other (referred to as "adjacent dot printing evaluation") and drying speed on recording paper (hereinafter referred to as "quick-dry evaluation"). Was provided to evaluate the color ink for inkjet printer of the present invention and the ink of Comparative Example.

Inks that could be printed in a suitable or suitable state for the above four evaluations were judged to be preferable as a color ink for ink jet printers, and an ink showing an unsuitable state was rejected. The evaluation results of the inks of Examples and Comparative Examples are shown.

[0024]

[Table 2]

Evaluation of paper type compatibility: Examples 1 to 32 of the present invention
Inks of Comparative Examples 1 to 4 and the inks of Comparative Examples 1 to 40
24 copy paper, R paper (recycled paper) from Xerox Co., P paper from Xerox Co., and bond paper (can color paper) were printed and evaluated according to the following classification. The results are shown in Table 2.

There is no difference in the print quality (the cleanness of the apparent characters) depending on the paper type ..... Suitable (⊚) The difference in the graphic part can be confirmed depending on the paper type. ◯) Character portion varies depending on paper type ... Inappropriate (x) Dot overlay printing evaluation: FIG. 1 shows an explanatory diagram of dot overlay printing evaluation. As shown in FIG. 1A, one pixel is a 4 × 4 pixel.
Divided into 6 (numbered 1 to 16 in the figure) yellow is shown in FIG. 1 (b), magenta is shown in FIG. 1 (c), and cyan is shown in FIG.
(D) and black are printed with the printing pattern of FIG. 1 (e) in the printing order of yellow, magenta, cyan, and black with the inks of Examples 1 to 32 of the present invention and the inks of Comparative Examples 1 to 4. The combinations of the colors of yellow, magenta, cyan, and black evaluated this time are shown in Table 3 as the ink combinations of the dot overlap printing test of the examples and comparative examples of the present invention.

[0027]

[Table 3]

After completion of printing the print pattern, the divided portion 1,
About 5, 6, 7, and 8 (the part where each color ink overlaps) 5
The degree of ink bleeding (spreading) was observed with a microscope of 0 times, and evaluated according to the following classification. The results are shown in Table 2.

The dot diameters at the divided portions 1, 5, 7, 8 are 100 μm or less ... Suitable (⊚) The dot diameters at the divided portions 1, 5, 7, 8 are 100 to 12
0 μm ... Appropriate (∘) The diameter of the dots in the divided portions 1, 5, 7, 8 is 120 μm or more ... Inappropriate (×) Adjacent dot print evaluation: FIG. 2 shows an explanatory diagram of adjacent dot print evaluation. In the figure, as shown in FIG.
It was divided into 6 parts (numbered 1 to 16 in the figure). In addition, solid printing is performed in different colors for the shaded portion and the white portion in FIG. The ink for printing the shaded area was A color, and the ink for printing the white area was B color. If the ink color to be evaluated is yellow, it is assumed that A color is printed with the inks of Examples 1 to 11 and B color is uniformly printed with magenta, cyan, and black, respectively. In the evaluation, the printing evaluation pattern was obtained by unifying magenta with the ink of Example 24, cyan with the ink of Example 26, and black with the ink of Example 32. When the ink to be similarly evaluated is magenta, the color A is the ink of Examples 12 to 24,
For the B color, yellow is the ink of the second embodiment, and cyan is the second embodiment.
The ink of 6 and black were unified with the ink of Example 32 to obtain a print evaluation pattern. When evaluating cyan, A
Colors were the same as those of Examples 25 to 30, B was yellow, the ink of Example 2 was the same, magenta was the ink of Example 24, and black was the ink of Example 32. In the case of evaluating black, the color A is the inks of Examples 31 and 32, the color B is the ink of Example 2 for yellow, the ink of Example 24 is for magenta, and the ink of Example 26 is for cyan. Obtained. After completion of the print evaluation pattern, the portions 6, 7, 10 and 11 in FIG. 2 were classified and evaluated as shown below. The results are shown in Table 2.

The dot adjoining surface at the boundary is clear ... Suitable (⊚) Color-mixed portion is 20% or less with respect to the area of 4 dots ... Suitable (○) Color-mixed portion is 4 20% or more of the dot area is not suitable (×) Quick-drying property evaluation: The inks of Examples 1 to 32 of the present invention are solidly printed on the P paper of Xerox Co., and further recorded on the recording portion immediately after printing. Overlay another P-paper of Xerox Co., 300gf /
It was pressed by a roller with a force of cm ³ (assuming the finger pressure of a person holding a paper), and evaluated according to the following classification. The results are shown in Table 2.

Ink does not transfer to the stacked papers ... Suitable (⊚) Ink of the stacked papers transfers ... Not suitable (x) The evaluations of Comparative Examples 1 to 4 of the present invention correspond to the paper types described above. The rate evaluation, dot overlay printing evaluation, adjacent dot printing evaluation, and quick drying property evaluation were performed in the same manner as in the example evaluation method of the present invention.

Data printing for each of the evaluation items described above was performed using an ink jet printer head as shown in FIG.
FIG. 3 is a sectional view showing the ink jet head structure used in this embodiment. Specifically, on the wall surface of the cavity 33,
It has a structure in which a pressure generating member 32 composed of stacked piezoelectric elements is bonded. At the time of driving, the pressure generating member 32 is bent by the applied voltage to pressurize the ink in the cavity, so that the ink is ejected from the nozzle 1.
In FIG. 3, 34 in FIG. 3 is ink, and 35 is an ink droplet ejected from the nozzle 31. The inkjet printer head is provided with Y, M, C, and Bk printing nozzles, one for each, and the printing order is controlled so that ink is ejected in the order of Y, M, C, and Bk. The discharge nozzle diameter is 5
0 μm, piezoelectric element drive voltage 50 V, drive frequency 2 kHz
z, resolution 300 dots / inch.

According to the structure of the ink jet printer head as described above, since the ejection speed is high, the ink transfer area is wide, the number of dots can be reduced, the resolution can be increased, and the margin for the ink physical properties such as viscosity and surface tension can be increased. It has excellent characteristics as an ink jet printer, such as a wide range and is less likely to be clogged.

As can be seen from the evaluation results in Table 2, the inks of Examples 1 to 32 of the present invention are good in all of the evaluation items of this time, that is, evaluation of paper type compatibility, dot overlay printing evaluation, and adjacent dot printing evaluation. The results are shown, which was preferable as a color ink for inkjet printers.

On the other hand, with the inks of Comparative Examples 1 to 4, it is possible to obtain a fine graphic or image from the evaluation results for this evaluation item, to the extent that the color can be confirmed (recognized) as a color ink for an inkjet printer. It was confirmed that it was difficult, and that it was not compatible with the paper type and that the drying speed on the recording paper was slow.

Although the embodiments of the present invention have been described in detail above, the color ink for an ink jet printer of the present invention is not limited to these constitutions and manufacturing methods.

[0037]

As described above, according to the color ink for the ink jet printer of the present invention, the print quality greatly depends on the paper type, which is a concern of the water-based ink, which has been a problem in the past. Ink bleeding occurs at the portions where the C and Bk dots overlap, resulting in a decrease in resolution. When dots are printed adjacent to each other, the inks mix and the bleeding at the dot boundary, color unevenness, and turbidity cause deterioration in image quality. It is possible to solve the problem that the printing speed cannot be increased because the drying speed on the recording paper is slow.

Further, the conventional water-based ink has been problematic in the corrosiveness of the head member or the light resistance and water resistance of the recorded matter.
The color ink for inkjet printers of the present invention is also effective for this problem.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of dot overlay printing evaluation of a color ink for an inkjet printer of the present invention.

FIG. 2 is an explanatory diagram of evaluation of adjacent dots of color ink for inkjet printer of the present invention.

FIG. 3 is a cross-sectional view showing the structure of an inkjet printer head used for ejecting the inkjet printer ink of the present invention.

[Explanation of symbols]

 31 Nozzle 32 Pressure Generating Member (Multilayer Piezoelectric Element) 33 Cavity Member 34 Ink 35 Ink Drop

Claims (3)

[Claims] 1. A color ink for an ink jet printer, comprising at least a pigment exhibiting yellow, magenta, cyan and black colors and a resin component, and dispersing the pigment in a non-aqueous solvent in which the resin component is dissolved. 2. Acrylic ester copolymer resin, rosin resin, hydrogenated terpene resin, alkylphenol resin, aromatic oligomer resin, alicyclic saturated hydrocarbon, hydrogenated dicyclopentadiene, aliphatic carbonized resin component. The color ink for an inkjet printer according to claim 1, wherein the color ink is selected from hydrogen resins. 3. A yellow pigment is a monoazo pigment, a disazo pigment, an azo lake pigment, a condensed azo pigment, an acid dye lake pigment, a basic dye lake pigment, an anthraquinone pigment, an isoindolinone pigment, a quinophthalone pigment, an isoindoline pigment. , Niloroso pigments, metal complex salt azomethine pigments, pigments exhibiting magenta color are monoazo pigments, disazo pigments, azo lake pigments, condensed azo pigments, acidic dye lake pigments, basic dye lake pigments, anthraquinone pigments, thioindigo pigments, Perinone pigments, perylene pigments, quinacridone pigments, isoindolinone pigments, alizarin lake pigments, and cyan pigments are disazo pigments, phthalocyanine pigments, acid dye lake pigments, basic dye lake pigments, anthraquinone pigments, alkalis. Bull 2. The color ink for an ink jet printer according to claim 1, wherein the pigment exhibiting a black color is selected from aniline black pigments and carbon black.