JPH06145571A - Ink for ink jet printer - Google Patents

Abstract

PURPOSE:To fix an image on a transfer medium without fail and obtain a high-quality character or image with a high blackness on a recording medium by compounding an iron oxide pigment and a dye as the color components into an ink for a transfer-type ink jet printer. CONSTITUTION:The ink contg. an iron oxide pigment and a dye as the color components is used in a transfer-type ink jet printer with which the ink is jetted as ink drops onto a transfer medium followed by the transfer of the ink to a recording medium.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink for an ink jet printer used in a transfer type ink jet recording apparatus.

[0002]

2. Description of the Related Art As a conventional technique, an ink jet recording apparatus (hereinafter, referred to as an ink jet recording apparatus that ejects ink from an ink ejection head onto a transfer medium to form an ink image on the transfer medium, and further transfers the ink image from the transfer medium to the recording medium) A transfer type ink jet printer) is reported in JP-A-62-92849 and JP-A-1-226336. In this device, ink is once ejected from the ink ejection head onto a non-absorptive transfer medium, and in some cases the ink component is evaporated there, and then the ink image is transferred onto the target recording medium. However, it is intended to achieve high print quality on various recording media.

[0003]

In the transfer type ink jet printer, it is required that the formation of an ink image on the transfer medium (hereinafter referred to as image fixing) is performed well.

However, according to the research conducted by the present inventor,
When a conventional transfer-type inkjet printer is used, the adhesive force between the ink and the transfer medium is increased by various means such as the wettability of the ink to the transfer medium or the increase in viscosity when the image is fixed. If the material of the transfer medium is not selected, the ink image on the transfer medium causes image deletion (the image is not formed at the position on the transfer medium that should originally be fixed) and is transferred to the recording medium as it is. It has been confirmed that when graphic printing is performed, a straight line is distorted or partially bulged on the transfer medium, and uneven density occurs even in a solid portion.

Therefore, the present inventor has proposed a method of fixing an image on a transfer medium by using an ink containing iron oxide as a coloring material while giving a magnetic force to the transfer medium. However, depending on the ink used in this method, it has been possible to solve the conventional problems of graphic distortion and uneven density in solid areas, but since the coloring material is a small amount of iron oxide, it can be used during transfer recording. The color of the recorded matter becomes brownish and the outline of the image is visually blurred so that the effect of the transfer recording cannot be clearly shown and O.I. There was a problem that the D value was also reduced.

Therefore, the ink for an ink jet printer of the present invention has been made in view of the above-mentioned problems of the prior art. The purpose of the ink is to reliably fix an image on a transfer medium in a transfer type ink jet printer. An object of the present invention is to provide an ink for an ink jet printer capable of obtaining characters and images having a higher degree of blackness without causing distortion of characters and graphics on a recording medium or a contour of a recorded matter, and further without causing uneven density in a solid portion. .

[0007]

The ink for an ink jet printer of the present invention is for an ink jet printer to be used in an ink jet recording apparatus for ejecting the ink as ink droplets onto a transfer medium and then transferring the ink on the transfer medium to the recording medium. An ink, characterized in that it contains at least an iron oxide pigment and a dye as coloring components in the ink composition.

[0008]

When the ink containing the iron oxide pigment and the dye ejected from the ink ejection head reaches the transfer medium, the iron oxide pigment, which is a coloring component, becomes a magnetic line of force from the magnetism generating means provided in the transfer medium. By being magnetically oriented along the direction, the image is fixed without causing image deletion, and by adding a dye, an ink image having high blackness and high printing density is formed. By using a dye and iron oxide pigment in combination,
The outline of the image becomes clear. Then, the ink image is transferred to the recording medium as it is on the transfer medium.

[0009]

EXAMPLES The ink for an ink jet printer of the present invention will be specifically described.

The essential components of the present invention include iron oxide pigments,
It is a dye and a solvent. In addition to these, a resin or the like is added for the purpose of adjusting the viscosity of the ink, ensuring the dispersion stability of the iron oxide pigment, transferring from the transfer medium to the recording medium, and increasing the fixing strength of the ink on the recording medium. Each composition will be described step by step.

1. Iron Oxide Pigment In the present invention, the iron oxide pigment is obtained by a method in which ferrous oxide and ferric oxide are precipitated in water as iron oxide colloids.
The specific manufacturing method is shown in the manufacturing method of the explanation part of the embodiment, but is not limited to these.

2. Dye It is preferable that the dye is stably dissolved in the solvent,
Nitro and nitroso dyes, stilbene dyes, pyrazolone dyes, thiazole dyes, azo dyes, pyrazolone dyes,
Carbonium dyes, azine dyes, oxazine dyes, thiazine dyes, sulfur dyes, pyridine and quinoline dyes, quinone imine dyes, indigo dyes, indigoid dyes, anthraquinone dyes, phthalocyanine dyes, cyanine dyes, etc. For correction, black or blue dyes are desirable. Specific examples are given below.

For example, when the solvent is a hydrophilic solvent,
As a preferable example of this, as a specific example, C.I. I. Direct Blue 1, 7, 9, 22, 23, 25, 2
9, 40, 41, 43, 45, 78, 80, 82, 9
2, 127, 249, C.I. I. Acid Blue 1,
7, 9, 22, 23, 25, 29, 40, 41, 43,
45, 78, 80, 82, 92, 127, 24, C.I.
I. Basic Blue 1, 3, 5, 7, 9, 22, 2
4, 25, 26, 28, 29, C.I. I. Direct Black 2, 7, 19, 22, 24, 32, 38, 51,
56, 63, 71, 74, 75, 77, 78, 86, 1
08, 154, 199 C.I. I. Acid Black 1, 2, 7, 24, 26,
29, 31, 44, 48, 50, 52, 94, 172,
208 C. I. Basic Black 2, 8 and so on.

For example, when the solvent is a hydrophobic solvent, specific examples of the preferred examples include C.I. I. Solvent Blue 2, 6, 11, 12, 15, 20, 25,
30, 31, 32, 35, 36, 55, 58, 71, 7
2, 73, C.I. I. Solvent Black 3, 5, 7,
10, 11, 12, 13, 22, 23 C.I. I. Disperse Yellow 1, 3, 4, 7, 8,
31, C.I. I. Disperse Red 1, 4, 5, 7,
11, 12, C.I. I. Disperse Blue 1, 3,
5, 6, 7, 27, C.I. I. Disperse Black
1, 2, 10, 26, 27, 28 etc. can be mentioned.

3. Solvent As the solvent of the ink of the present invention, a hydrophilic solvent or a hydrophobic solvent can be used. The hydrophilic solvent that can be used in the present invention, water or ethanol, alcohols such as propanol, glycerin, ethylene glycol, high boiling point low volatility and high surface tension polyhydric alcohols such as diethylene glycol, further triethylene glycol, Polyhydric alcohols such as propylene glycol and polyethylene glycol, or their monoethers, diethers, and esters, such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether. , Diethylene glycol monobutyl ether, etc., other N-methyl-2pyrrolidone, 1.
There are water-soluble organic solvents such as nitrogen-containing organic solvents such as 3-dimethylimidazolidinone and ethylformamide.

As the hydrophobic solvent which can be used in the present invention,
Silicon oil having a siloxane bond, isobutylene, vinyl chloride, and the like, as well as non-polar solvents such as mineral spirit, pentane, hexane, octane, petroleum naphtha, cyclohexane, heptane, and the like can be used.

4. In addition to resins, resins may be added for the purpose of adjusting the viscosity of the ink, ensuring the dispersion stability of the iron oxide pigment, and improving the transferability from the transfer medium to the recording medium and the adhesive strength of the ink on the recording medium. I can. Specific examples are given below.

In the present invention, as a water-soluble resin suitable for an ink using a hydrophilic solvent, there is a natural polymer type, and examples thereof include gelatin, casein, gum arabic, starch, modified starch (starch acetate, hydroxystarch, amine). Starch, dialdehyde starch), cellulose derivatives (methyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose), sodium alginate, etc., and synthetic polymers such as polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylic acid soda, polyacrylic acid amide, polyethylene oxide, polyethylene. There are imines, etc.

In the present invention, the oily resin suitable for the ink using the hydrophobic solvent is ethyl cellulose resin,
Polyacrylic ester resin, linseed oil modified alkyd resin, polyvinyl chloride resin, polypropolene chloride, polyamide resin, coumarone indene resin, rosin resin, terpene phenol resin, alkylphenol modified xylene resin, maleic anhydride resin, isoprene resin, styrene Resins, ethylene / methacrylic acid copolymer resins, ethylene / ethyl acrylate copolymer resins, ethylene / vinyl acetate copolymer resins and the like are preferable.

From the viewpoint of ink storability, it is preferable that the water-soluble resin or oily resin is soluble in a solvent. Furthermore, from the viewpoint of blocking the recorded matter after printing. The melting point or softening point of the resin is preferably 50 ° C. or higher. Further, depending on the case, two or more kinds of resins may be used in combination.

In the present invention, when the iron oxide pigment is dispersed in a hydrophilic solvent or a hydrophobic solvent, a polymer compound generally called a surfactant or a dispersant may be basically used in combination. This may be an ionic (anionic or cationic), amphoteric or nonionic surfactant, or a fluorine-based, silicon-based or polymer-based surfactant or a polymer compound. The dispersants that can be used in the present invention are exemplified below.

For example, as the anionic surfactant, higher fatty acid salt, higher alkyl dicarboxylate, higher alcohol sulfuric acid ester salt, higher alkyl sulfonate, condensate of higher fatty acid and amino acid, sulfosuccinate ester salt, naphthenate salt Etc. As the cationic surfactant, an aliphatic amine salt, a quaternary ammonium salt, a sulfonium salt,
Specific examples of the phosphonium salt include octadecylamine acetate, alkyltrimethylammonium chloride, polyoxyethylene octadecylamine, polyoxyethylene alkylamine, and polymeric amine.

The amphoteric surfactant is a betaine type such as dimethylalkyl betaine. As the nonionic surfactant, a fatty acid ester type of polyoxyethylene compound, a polyethylene oxide condensation type or the like can be used.

As a preferable physical property of the ink for an ink jet printer of the present invention, the ink viscosity when the operating environment temperature during the operation of the printing device is set to 0 to 50 ° C. is the ink droplet formation under the high speed response of the head. From the viewpoint of stability and flight stability, 3 near the nozzle during ejection
It is necessary to be 0 mPa · s or less, and more preferably 1.0 to 15 mPa · s in order to realize even faster response.

Specific examples of the present invention using the above-described ink composition are shown below. (In addition, the percentages shown in the following compositions represent weight percentages unless otherwise noted) [Example 1] The final ink composition of Example 1 of the present invention is the following composition.

Iron oxide colloid (average particle size 100Å) 12.4% Sodium oleate 2% Ion-exchanged water 72.9% Ethanol 1.8% Glycerin 1.8% Polyvinyl alcohol 7.3% C.I. I. Basic Black 2 1.8% Next, a method for producing the above ink will be described.

The iron oxide colloid used in Example 1 was manufactured by the following operating method.

75 parts by weight of ferrous sulfate was added to 25 parts of ion-exchanged water.
It is dissolved in 0 part by weight, and separately from this, 200 parts by weight of ferric sulfate is added and dissolved in 450 parts by weight of ion-exchanged water, and both solutions are mixed. 6N sodium hydroxide was added to this,
Stir well to adjust to pH 11.5. Then this is 60 ℃
After stirring for 10 minutes, about 250 parts by weight of iron oxide colloid with an average particle size of 100Å is formed. Then, if necessary, a large-sized iron oxide colloid is removed by a centrifuge.

The iron oxide of Example 1 had an average particle size of 10
The shearing force during dispersion was adjusted so that the average particle diameter was 0 angstrom. Next, 270 g of a 15% aqueous solution of sodium oleate was added to the iron oxide colloid, and the mixture was heated to 80 ° C.
Adsorb for minutes.

Next, 561 parts by weight of deionized water, 36.7 parts by weight of ethanol, 146.8 parts by weight of polyvinyl alcohol (Denka Poval B03 manufactured by Denki Kagaku Kogyo Co., Ltd.), and 36.7 parts by weight of glycerin added C.I. I. 36.7 parts by weight of Basic Black is added to the solution and dissolved. This solution is added to the iron oxide colloidal dispersion prepared above and stirred to obtain the ink of Example 1 of the present invention.

Example 2 The final ink composition of Example 2 of the present invention is the following composition.

Iron oxide colloid (average particle size 200Å) 18% Sodium oleate 3% Ion-exchanged water 70% Ethanol 1% Glycerin 1% Polyvinylpyrrolidone 3% C.I. I. Direct Black 78 3% Dioctyl sulfosuccinate 1% Basically, the method for producing the ink for inkjet printer of Example 2 is the same as the method shown in Example 1. However, in the production of the iron oxide colloid, stirring was performed at 50 ° C. for 10 minutes, and the shearing force during dispersion was adjusted so that the average particle diameter of the iron oxide colloid was 200 angstroms.

Example 3 The final ink composition of Example 3 of the present invention has the following composition.

Iron oxide colloid (average particle size 200Å) 18% Sodium oleate 3% Ion-exchanged water 71% Ethanol 1% Glycerin 1% Polyvinyl alcohol 3% C.I. I. Direct Black 78 3% Basically, the method for producing the ink for an inkjet printer of Example 3 is the same as the method shown in Example 1. However, in the same manner as in Example 2, in the production of the iron oxide colloid, stirring was performed at 50 ° C. for 10 minutes, and the shearing force during dispersion was adjusted so that the average particle diameter of the iron oxide colloid was 200Å.

Example 4 The final ink composition of Example 4 of the present invention is the following composition.

Iron oxide colloid (average particle size 100Å) 20.3% Sodium oleate 5.2% Kerosene 66.5% Hydrogenated alicyclic hydrocarbon resin 4% C.I. I. Solvent Black 5 2% Polyoxyethylene trioleate 2% The ink of Example 4 was made using the flushing method.

Ferrous sulfate and ferric sulfate 1 mol aqueous solution 10
Add 00 ml to the mixing tank. 6N caustic soda is added dropwise to adjust the pH to 7.3 and stirred for 20 minutes to form an iron oxide colloidal solution. Next, 640 ml of 10% sodium oleate solution (amount enough to form a monomolecular adsorption layer) was added, and 3
When the mixture is stirred for 0 minutes, a magnetic particle-containing layer containing bubbles is formed in the upper layer. The lower layer is a layer containing water and sodium sulfate. When 400 ml of kerosene (ISOPER L manufactured by Exxon Chemical Co., Ltd.) was poured, bubbles were lost in the upper layer, and a blackish brown liquid layer oil was produced. Open the drain cock to let the clear liquid in the lower layer flow out. The blackish brown kerosene layer was transferred to a shaker, and 423.5 parts by weight of kerosene was added to the hydrogenated alicyclic hydrocarbon resin (Arcon P-90 manufactured by Arakawa Chemical Co., Ltd.).
50 parts by weight, C.I. I. A solution in which 25 parts by weight of Solvent Black 5 and 25 parts by weight of polyoxyethylene trioleate were dissolved and shaken for 30 minutes, and then a centrifugal separator was rotated at 4500 to 5000 rpm for 30 minutes to centrifuge large particles. The ink of Example 4 can be obtained. (Flushing Method) [Example 5] Example 5 of the present invention is manufactured by the same manufacturing method as Example 4, and the final ink composition is as follows.

Iron oxide colloid (average particle size 200Å) 25% Sodium oleate 3% Kerosene (Isopar L) 65% Hydrogenated alicyclic hydrocarbon resin (Alcon P-90) 5% C.I. I. Solvent Black 12 2% [Example 6] Example 6 of the present invention is manufactured by the same manufacturing method as that of Example 4, and the final ink composition is as follows.

Iron oxide colloid (average particle size 200Å) 20% Sodium oleate 3% Kerosene (Isopar L) 68% Hydrogenated alicyclic hydrocarbon resin (Alcon P-90) 5% C.I. I. Solvent Black 12 2% Polyoxyethylene trioleate 2% Next, a comparative example of the present invention will be described.

Comparative Example 1 The final ink composition of Comparative Example 1 of the present invention is as follows.

Iron oxide colloid (average particle size 100Å) 12.4% Sodium oleate 2% Ion-exchanged water 72.9% Ethanol 1.8% Glycerin 1.8% Polyvinyl alcohol 7.3% Dioctyl succinate 1. 8% (Sansepara 100 manufactured by Sanyo Kasei Co., Ltd.) The ink manufacturing method is almost the same as in Example 1.

Comparative Example 2 The final ink composition of Comparative Example 2 of the present invention has the following composition.

Ion-exchanged water 90% Ethanol 3% Glycerin 3% Polyvinyl alcohol 1% Basic black 2 3% In the production method of Comparative Example 2, polyvinyl alcohol (DENKA POVAL B0 manufactured by Denki Kagaku Kogyo Co., Ltd.) was used.
3) is dissolved, and then ethanol, glycerin, and basic black are added and dissolved in this order, to produce.

Comparative Example 3 The final ink composition of Comparative Example 3 of the present invention has the following composition.

Iron oxide colloid (average particle size 100Å) 20.3% Sodium oleate 5.2% Kerosene (Isopar L) 66.5% Hydrogenated alicyclic hydrocarbon resin (Arcon P-90) 4% Polyoxy Ethylene trioleate 4% The manufacturing method of Comparative Example 3 is almost the same as the manufacturing method of Example 4.

Comparative Example 4 The final ink composition of Comparative Example 4 of the present invention has the following composition.

Kerosene (Isopar L) 91% Hydrogenated alicyclic hydrocarbon resin (Alcon P-90) 5% Solvent Black 5 3% Polyoxyethylene trioleate 1% Comparative Example 4 was prepared by hydrogenating kerosene. In this method, an alicyclic hydrocarbon resin is dissolved, and then polyoxyethylene trioleate and Solvent Black 5 are added and dissolved in this order to produce.

Next, using a transfer type ink jet printer as shown in FIG. 1, for Examples 1 to 6 and Comparative Examples 1 to 4 of the present invention, distortion of characters and graphics on the recording medium, print density, The density unevenness of the solid part and the blackness of the recorded matter were evaluated.

The ink ejected as ink droplets from the ink ejection head 1 is magnetized by the magnetic force on the transfer medium 2,
The ink image 7 is fixed at the point where the ink reaches the transfer medium 2. After that, the transfer medium 2 is moved in the direction of arrow A shown in the figure.
Is rotated, and the ink image 7 on the transfer medium 2 is recorded on the recording medium 3 by the pressure of the pressure roller 4 installed via the recording medium 3.
Transfer to.

Here, the transfer medium 2 will be specifically described.

The transfer medium 2 is constructed by disposing a plastic bond magnet layer as a magnetism generating means on a drum made of a metal ring or the like, and further disposing a protective layer thereon. As the protective layer of the transfer medium 2 of the transfer type inkjet printer used for the evaluation of the present invention, a 2 μm thin film layer of PET was used. The plastic bond magnet layer is composed of repetitive magnetic domains having a pitch of about 8 μm between S and N poles. The leakage flux just above the plastic bond magnet layer was about 5000 gauss.

The ink ejection head 1 is a head using a piezoelectric element, and the ejection nozzle diameter is 50 μm, the piezoelectric element driving voltage is 50 V, the driving frequency is 2 kHz, and the resolution is 300 dots /
It was inches.

The linear pressure between the pressure roller 4 and the recording medium 3 (4024 paper manufactured by Xerox Co. was used for the evaluation of the present invention) was 0.7 kg / cm.

Evaluation items: The evaluation methods carried out for the examples and comparative examples of the present invention will be specifically described below.

1. Distortion of characters and graphics on recording medium A graphic pattern is printed on P-paper manufactured by Xerox Co., Ltd., and the presence or absence of distortion of the recorded matter is evaluated by visual observation or microscope observation (60 times) of the linear portion. No distortion can be confirmed.・ ・ ・ Suitable (⊚) ・ No distortion can be visually confirmed, but it can be confirmed by microscopic observation.・ ・ ・ Appropriate (○) ・ Distortion can be confirmed by both visual observation and microscopic observation. ... Classified and evaluated by unsuitability (x). (Note that the distortion was evaluated by including the bending of the line in the line portion and the bleeding of the recorded material). Density unevenness in solid area Solid printing was performed on P paper manufactured by Xerox Co., and the printing density (OD value) was measured by a microdensitometer manufactured by Konica, and the difference between the maximum value and the minimum value was evaluated according to the following classification.

・ 0.2 or less ・ ・ ・ Suitable (◎) ・ 0.2 to 0.4 ・ ・ ・ Appropriate (○) ・ 0.4 or more ・ ・ ・ Inadequate (×) 3. Printing Density Solid printing is performed on P-paper from Xerox Co., Ltd. The D value was measured and classified into the following.

1.25 or less ・ ・ ・ Inadequate (×) 1.25 to 1.35 ・ ・ Appropriate (○) 1.35 or more ・ ・ ・ Suitable (⊚) 4. Blackness: A solid image was printed on a transparent PET film, and the absorption wavelength was observed with a light-transmitting spectrophotometer (Microdensitometer reflection mode, Konica Corporation). The width of the intensity of the transmitted light over the visible light wavelength region centered on the average value was measured and evaluated according to the following classification.

・ Entering within the range of ± 20% ・ ・ ・ Suitable (◎) ・ Exceeding the range of ± 20% ・ ・ ・ ・ Inadequate (×) 5. Sharpness of the outline of the recorded matter A character pattern is printed on the P-paper of Xerox Co., and visually observed.-The outline of the character is clear -... Suitable (◎) -The outline of the character is unclear, at a glance It looks like bleeding ... It was classified and evaluated by unsuitability (x).

The above results are shown in Table 1.

[0060]

[Table 1]

As can be seen from the evaluation results in Table 1, when the ink for ink jet printer of the present invention was used, favorable evaluation results were obtained for all the evaluation items described above. However, Comparative Examples 1 and 3 were used for the blackness and print density of the recorded matter, Comparative Examples 2 and 4 were used for the distortion evaluation test of characters and graphic portions on the recording medium, and all Comparative Examples of the present invention were used. Is lacking in the sharpness of the outline of the recorded matter (in Comparative Examples 2 and 4, it seems that the outline of the recorded matter becomes unclear because the image is not fixed well on the transfer medium). The result of evaluation is unsuitable.

[0062]

By using the ink for an inkjet printer of the present invention, distortion of characters and graphics on the recording medium due to the image deletion of the ink image on the transfer medium, which has been a subject of the transfer type inkjet printer so far. Alternatively, there is an effect that uneven density in the solid portion does not occur. Further, by containing a dye and an iron oxide pigment in the ink composition, it has the effects of improving the print density of the recorded matter and making the outline of the recorded matter clear.

Further, when only the iron oxide pigment is contained in the ink as a coloring material, S is added when the image is fixed on the transfer medium.
When the repeating pitch of the magnetic domains of the pole and the N pole becomes large, orientation distribution of the iron oxide pigment occurs and printing density unevenness occurs, but when the ink for an inkjet printer of the present invention is used, it occurs as the repeating pitch of the magnetic domains becomes large. It also has an effect that the printing density unevenness due to the iron oxide pigment orientation does not occur, and at the same time, the cost of the plastic bonded magnet can be reduced.

[Brief description of drawings]

FIG. 1 is a perspective view of a transfer-type inkjet printer used for print evaluation in Examples and Comparative Examples of the present invention.

[Explanation of symbols]

 1 Ink ejection head 2 Transfer medium 3 Recording medium

Claims (1)

[Claims] 1. An ink for an inkjet printer, which is used in an inkjet recording apparatus that ejects an ink as an ink droplet onto a transfer medium, and then transfers the ink on the transfer medium to a recording medium, the ink being used as a coloring component in at least the ink composition. An ink for an inkjet printer, which contains an iron oxide pigment and a dye.