JPH0978014A - Ink composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an ink composition capable of effectively suppressing bubble generation and free from print falling off of printed line caused by bubbles in the ink, free from imparting undesirable effect to material such as cloth, etc., to be printed with this ink and excellent in preservative quality by mixing an mineral oil to a liquid medium dispersing pigment. SOLUTION: This ink composition comprises (A) a liquid medium containing dispersed pigment, (B) an mineral oil (for example liquid paraffin, spindle oil, light oil, lamp oil, motor oil, cylinder oil and machine oil) and if necessary (C) a surface active agent (for example an adduct of ethylene oxide to fatty acid, an adduct of ethylene oxide to alcohol, oils and fats) preferably containing more than 0.01wt.ppm more preferably >=1000ppm of B.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is capable of clearly drawing lines and characters not only on paper but also on objects to be drawn such as cloth, leather and paper, by using an ink discharge type image forming apparatus. The present invention relates to an ink composition.

[0002]

2. Description of the Related Art Conventionally, as an ink composition for an ink discharge type image forming apparatus, an aqueous ink composition in which a dye or pigment is dispersed in an aqueous medium such as water or a water-soluble organic solvent, or an organic solvent or wax is used. An oil-based ink composition in which dyes and pigments are dispersed in an oil-based medium is known.

In the ink ejection type image forming apparatus, ink is ejected from an ink jet head containing ink to form an image line. For this reason, it is necessary to inject the ink into the inkjet head, which may adversely affect the image quality, such as missing of printing on an image line due to the generation of bubbles during the injection.

As a method for suppressing bubbles in the ink composition for an ink-jet image forming apparatus, Japanese Patent Laid-Open No. 63-
Those containing a lower alkyl alcohol described in JP-A-139963 are known. However, when the material to be drawn is a cloth, the lower alkyl alcohol may have an adverse effect such as the surface treatment agent or dye of the cloth being dissolved and the color and texture of the cloth being impaired. Further, the lower alkyl alcohol has a strong effect of eliminating the bubbles already generated, but has a small ability to suppress the generation of bubbles continuously. In addition, it is liable to evaporate and the storage stability is poor. In addition, alcohol may diffuse into the environment and give off odor.

[0005]

As described above, when a lower alkyl alcohol is contained for the purpose of suppressing the generation of bubbles in the ink composition for an ink discharge type image forming apparatus, an object to be drawn is When used as a cloth, it may adversely affect the cloth, such as bleeding of the surface treatment agent or dye of the cloth. Further, it is difficult to continuously and strongly suppress the generation of bubbles. In addition, since it easily evaporates, the concentration in the ink composition is lowered, and the effect of suppressing bubbles is reduced, resulting in poor storage stability. Further, odor may be generated due to evaporation and diffusion of gas.

In view of the above, the present invention provides an ink for an ink-jet type image forming apparatus, in which the inclusions for suppressing air bubbles strongly suppress the generation of air bubbles continuously and do not adversely affect the cloth. It is intended to provide a composition.

[0007]

In order to achieve this object, the ink composition according to the first aspect of the present invention is a liquid medium in which a coloring material is dispersed and which contains mineral oil. Therefore, by containing the mineral oil, the generation of bubbles is continuously suppressed.

The ink composition according to claim 2 is
The liquid medium further contains a surfactant. Therefore, the surfactant uniformly disperses the mineral oil in the liquid medium and more strongly suppresses the generation of bubbles.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments in which the ink composition of the present invention is embodied will be described below.

The ink composition of the present embodiment contains mineral oil to suppress the generation of air bubbles, thereby preventing the printing of image lines from being omitted, and obtaining a good image. .

Mineral oil is a mixture of paraffinic, naphthenic and aromatic hydrocarbons which is refined from petroleum and has a boiling point range of 90 ° C to 550 ° C, particularly 200 ° C to One having a temperature of 500 ° C. is preferably used. Specific examples include liquid paraffin, spindle oil,
Examples include light oil, kerosene, motor oil, cylinder oil, machine oil and the like.

The mineral oil of this embodiment may be a mixture of the above-mentioned mineral oils alone. In addition, mineral oil may be mixed with fine powder of silicon oxide, fatty acid amide, polyethers, metal soap or the like to improve the defoaming ability.

Further, it is possible to improve the dispersibility in the liquid medium constituting the ink by mixing the surfactant with the mineral oil. As the surfactant, fatty acid ethylene oxide adducts, alcohol ethylene oxide adducts, fats and oils, ester compounds and the like are preferably used.

The mineral oil of the present embodiment continuously and strongly suppresses the generation of bubbles. In addition, it does not evaporate and does not generate odor. In addition, since the concentration does not decrease even after long-term storage, the storage stability is excellent. Further, since the reactivity is low, there is no problem that the dye and the surface treatment agent are dissolved and the color and texture are impaired even when the object to be drawn is a cloth.

Furthermore, it is not necessary to use expensive silicone oil as the defoaming component, and bubbles can be suppressed at low cost.

As the composition of the ink composition for an ink jet type image forming apparatus, the composition of conventionally used ink can be applied as it is. The object of the present invention can be achieved by adding to these ink compositions one of the mineral oils of the present embodiment, which is easily dissolved or dispersed in the solvent of the ink composition and which has a large defoaming effect. You can If necessary, an organic solvent can be added in the range of 50% by weight or less when water is used as the solvent. Also,
Water may be added in the range of 50% by weight or less when the organic solvent is used as the solvent. It is also possible to mix two or more kinds of organic solvents at an arbitrary ratio.

As the organic solvent, alkyl alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol, n-propyl alcohol, n-butyl alcohol, sec-butyl alcohol and t-butyl alcohol; amides such as dimethylformamide and dimethylacetamide. Ketones or ketone alcohols such as acetone and diacetone alcohol; tetrahydrofuran,
Ethers such as dioxane; polyethylene glycol;
Polyalkylene glycols such as polypropylene glycol; ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1, 2,
Alkylene glycols such as 6-hexanetriol, thiodiglycol, hexylene glycol and diethylene glycol; cellosolves such as methyl cellosolve and ethyl cellosolve; polyhydric alcohols such as glycerin, ethylene glycol and diethylene glycol, diethylene glycol dimethyl (or ethyl) ether, Examples thereof include lower alkyl ethers of polyhydric alcohols such as carbitol and triethylene glycol monomethyl ether; and carbitol acetate.

Further, as an ink discharge type image forming apparatus, a negative pressure is generated by a flow of air inserted into an ink jet head containing an ink described in Japanese Patent Laid-Open No. 4-91207 to discharge the ink. , A cloth, leather, paper, or the like, and a relative movement of an inkjet head and an inkjet head to draw a predetermined pattern.

An example of the ink composition for the air jet type marking device is, for example, JP-A-4-2390.
The water-soluble white powder described in Japanese Patent Publication No. 69, and the one obtained by finely dispersing it in a hydrophilic organic solvent having a small dissolving power to the powder and adding a white pigment for increasing the white hiding power can be mentioned. This ink composition is an ink capable of erasing the lines drawn by washing with water, but the mineral oil of the present embodiment has a great effect of suppressing bubbles, and only a very small amount is added to the ink composition. Since air bubbles are suppressed by
Only a small amount needs to be added. Therefore, the erasability by washing with water is not lost.

The content of the mineral oil of the present embodiment in the ink composition needs to be sufficient to suppress air bubbles, and if it is appropriately contained depending on the ability of the mineral oil used. Good, but generally 0.01 wtppm or more,
More preferably 1 wtppm or more, and even more preferably 1
It is necessary to contain more than 00 wtppm.

An embodiment based on the above contents will be described below.

(Example 1) Ingredients in the examples of inks for ink jet printers are: carbon black (# 960, manufactured by Mitsubishi Chemical Co.) 50 parts by weight Dispersant Disperbyk (manufactured by BYK-Chemie) 50 parts by weight Polyvinyl alcohol (electrochemical) Kogyo Co., Ltd. B03) 10 parts by weight Glycerin 100 parts by weight Defoamer (San Nopco's Nopco 8034-L) 3 parts by weight Pure water 790 parts by weight. The antifoaming agent is a mixture of mineral oil and a nonionic surfactant.

First, glycerin in water and the dispersant Dispe
dissolve rbyk, polyvinyl alcohol, antifoaming agent,
After that, carbon black was added and sufficiently stirred to form a homogeneous dispersion liquid. No bubbles were observed in this dispersion when it was injected into an inkjet head. Further, as compared with the case where the defoaming agent was not added, the influence of the change in viscosity was not observed. In addition, when this dispersion was used as an ink for a commercially available inkjet printer, characters and lines could be drawn well without any problems.

Example 2 An example of an ink composition used in an air jet type marking device is as follows: L-glutamic acid 230 parts by weight Titanium oxide (anatase type) 13 parts by weight Polyethylene glycol 280 parts by weight Ethylene glycol 300 parts by weight Defoaming 2 parts by weight of the agent (SN Deformer 5013 manufactured by San Nopco). The defoaming agent is a mixture of mineral oil, a nonionic surfactant, a fatty acid amide and the like.

First, a predetermined amount of butyl cellob, polyethylene glycol, L-glutamic acid and titanium oxide were sequentially added to ethylene glycol and sufficiently stirred to obtain a homogeneous dispersion liquid. When this dispersion was stored for a long period of time, titanium oxide precipitated, and it was necessary to shake to redisperse the titanium oxide, but no bubbles were observed even when shaken. When a character or figure was drawn on a dark-colored cloth with an air jet type marking device using this dispersion liquid, a white printing line with no missing print was obtained, and after about 10 minutes, the solvent penetrated into the drawing object. However, a part of it evaporated and became a clear image. When the steam iron was applied one hour after the drawing, the image lines did not disappear at all, and when washed with water, the image lines disappeared completely.

(Example 3) In this example, the ink composition used for the air jet type marking device is also described below. White polymerized resin particles (MBX-20 white manufactured by Sekisui Kasei) 150 parts by weight Polyethylene glycol 85 parts by weight Smectite (Corp Chemical) 15 parts by weight of hydrophilic smectite SWN manufactured by the company, 3 parts by weight of antifoaming agent (SN Deformer 5016 manufactured by San Nopco), and 755 parts by weight of pure water. The antifoaming agent is a mixture of mineral oil and a nonionic surfactant.

First, a predetermined amount of smectite is dispersed in water, and then a predetermined amount of polyethylene glycol and an antifoaming agent are added and dissolved therein. Further, white polymerized resin particles are added and sufficiently stirred to homogenize. Dispersion. When this dispersion was allowed to stand for 6 hours, the viscosity increased to a jelly-like state, and it was allowed to stand for 3 weeks, but no change was observed. Then, when it was shaken, it returned to a liquid state, and the addition of the antifoaming agent did not adversely affect the thixotropic property. Also,
No bubbles were generated, and the effect of suppressing bubbles was sufficiently maintained. When this dispersion was used to draw on a dark-colored fabric with the above-mentioned ink jet marking device in the same manner as in Example 2, a clear white line with no printing omission was drawn, and when a steam iron was applied 1 hour after drawing, the line was drawn. Never disappears. After washing with water, the stroke disappeared completely.

(Comparative Example 1) A comparative example of an ink for an ink jet printer is as follows: 50 parts by weight of carbon black (# 960, manufactured by Mitsubishi Chemical Corporation) Dispersant Disperbyk (manufactured by BYK-Chemie) 50 parts by weight Polyvinyl alcohol (Denki Kagaku Kogyo KK) B03) 10 parts by weight Glycerin 100 parts by weight Pure water 790 parts by weight

A dispersion was obtained in the same manner as in Example 1 except that the defoaming agent was not added. When this dispersion liquid was used as an ink for a commercially available inkjet printer, when this dispersion liquid was injected into an inkjet head, bubbles were generated, and the generated bubbles caused some print defects.

Comparative Example 2 A comparative example to Example 2 is: L-glutamic acid 230 parts by weight Titanium oxide (anatase type) 13 parts by weight Polyethylene glycol 280 parts by weight Ethylene glycol 300 parts by weight.

The same procedure as in Example 2 was repeated except that butyl cellosolve was not added to ethylene glycol.
A dispersion was prepared. When this dispersion was drawn on a dark-colored cloth with an air jet marking device, characters and figures were drawn.
A white image was obtained, and after about 10 minutes, the solvent penetrated into the object to be drawn, and part of it evaporated to form a clear image. It was

(Comparative Example 3) A comparative example with respect to Example 3 is as follows: White polymer resin particles (MBX-20 white manufactured by Sekisui Kasei Co., Ltd.) 150 parts by weight Polyethylene glycol 85 parts by weight Smectite (hydrophilic smectite SWN manufactured by Corp Chemical) 15 Parts by weight Defoamer (SN Deformer 381 manufactured by San Nopco) 3 parts by weight Pure water 755 parts by weight. The antifoaming agent is a mixture of a nonionic surfactant, a preservative and water.

Example 3 except that the defoamer was changed.
The same operation as above was performed to prepare a dispersion liquid. A slight amount of bubbles were observed in this dispersion liquid, and when drawing was performed using the air jet type marking device using this dispersion liquid, a slight print omission occurred in the image line.

By containing the defoaming agent containing the mineral oil as in the above-mentioned embodiment, the generation of bubbles in the ink composition is suppressed, and it is possible to prevent printing defects due to bubbles in the image lines. As a result, good drawing can be obtained. Further, even if the defoaming agent is added, there is no problem in the function as an ink, an inkjet printer,
Alternatively, it could be used in an air jet type marking device. Further, it rarely emits an offensive odor peculiar to ink.

According to the ink of this embodiment described above,
By containing mineral oil in the ink composition, the generation of bubbles is suppressed, and a good image can be obtained without causing printing defects of image lines due to the generation of bubbles. Also in this case, an unusual odor peculiar to the ink is rarely emitted. In addition, the mineral oil does not evaporate easily, so the storage stability is good. Further, when the object to be drawn is a cloth, the reactivity of the mineral oil is small, so that the dye and the surface treating agent are not dissolved and the color and texture are not impaired.

Further, the ink composition of the present embodiment is well adhered to a cloth, a leather, etc. by an air jet type marking device, that is, when a character, an image line, etc. is drawn on the cloth, the leather etc. , Without causing shrinkage on leather, etc.
It is possible to reliably draw a character, an image line, or the like, which does not cause printing omission, without causing bleeding of the dye on the cloth.

[0037]

As is clear from the above description,
Since the ink composition according to claim 1 of the present invention contains the mineral oil in the liquid medium in which the coloring material is dispersed, the generation of air bubbles is suppressed, and the generation of air bubbles does not result in missing printing of image lines. ,
A good image can be obtained.

Further, in the ink composition according to the second aspect, since the liquid medium further contains a surfactant, the mineral oil is uniformly dispersed in the liquid medium by the surfactant,
The effect of suppressing the generation of stronger bubbles can be obtained.

[0039]

Claims (2)

[Claims] 1. An ink composition for an ink ejection type image forming apparatus, characterized in that a liquid medium in which a coloring material is dispersed contains mineral oil. 2. The ink composition according to claim 1, wherein the liquid medium further contains a surfactant.