JPH03157464A - Ink composition for ink jet - Google Patents

Abstract

PURPOSE:To provide the title composition excellent in the dispersion stability for a pigment used and dryability and capable of giving printed images of high light and water resistance, etc., comprising a pigment, polymer dispersant, specific aqueous medium and acetylene series glycol-based penetrant. CONSTITUTION:The objective composition can be obtained by mixing and grinding, using e.g. a homomixer, a blend of (A) 3-10wt.%, based on the final composition, of an organic or inorganic pigment, (B) 3-100 pts.wt., based on the component A, of a polymer dispersant 1000-100000 in molecular weight (if needed, a water-soluble resin may be added), (C) an aqueous medium comprising 100 pts.wt. of water, 30-80 pts.wt. of a nonvolatile organic solvent such as ethylene glycol and 5-30 pts.wt. of a lower alcohol, and (D) 0.05-1.0 pt.wt., based on 100 pts.wt. of the final composition, of a penetrant, a compound of pref. formula I or II (m+n=3-30), and furthermore, if needed, (E) other ingredient(s).

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an ink composition for IJ (ink jet), and more specifically, when recorded on a liquid-absorbing recording object, the appearance is The present invention relates to an IJ ink composition that has an excellent drying speed and is capable of forming images with excellent fastness.

(Prior art and problems) Conventionally, the IJ recording method has been widely used, for example,
When using the IJ recording method for marking packaging materials, etc., image formation with high fastness such as light resistance and water resistance is required, and the recording object is cardboard paper, etc.
If the object is absorbent, such as paperboard or cloth, the ink droplets will adhere to the object and dry quickly, and even if it comes into contact with other objects, the recording will not collapse or contaminate other objects. This is required.

Problems with fastness such as light resistance and water resistance can be solved by using pigments as colorants, but since the IJ recording method is a method in which minute droplets are ejected from the tip of a minute nozzle, Ink drying and clogging are major problems.

The present inventor previously solved the above problem by using a specific polymer dispersant as a pigment dispersant and by incorporating a nonvolatile organic solvent such as ethylene glycol into the ink composition.

The above ink composition by the present inventor gives an image with excellent fastness, but when the ink composition is applied to a highly absorbent recording object, the ink contains a non-volatile organic solvent and a non-volatile organic solvent. Due to the presence of polymeric dispersants,
There is a problem in that the liquid absorption of the ink medium by the recording object is slow (apparently *2 the drying speed is insufficient).

As a method of improving the drying speed, a method of adding an acetylene glycol derivative in an amount of 1 to 10% by weight to the ink is known (see Japanese Patent Application Laid-Open No. 158083/1999). When applied to inks containing non-volatile organic solvents and polymeric dispersants, the penetrating agent has insufficient solubility in the ink medium and does not blend into the ink, causing the penetrating agent to separate as an oil layer, significantly impairing the dispersion stability of the pigment. In addition, there was a problem that a sufficient permeation effect could not be obtained, and therefore a sufficient drying rate could not be obtained.

Therefore, an object of the present invention is to provide an IJ ink composition that has an apparently high drying speed and can form images with excellent light fastness, water resistance, etc., without impairing the dispersion stability of pigments. It is to be.

(Means for solving problems) The above objects are achieved by the present invention as described below.

That is, the present invention comprises a pigment, a polymer dispersant, an aqueous medium, and an acetylene glycol penetrating agent, and the aqueous medium comprises water, a nonvolatile organic solvent, and a lower alcohol,
An IJ ink composition characterized in that the amount of the penetrant is in the range of 0.05 to 1% by weight of the ink.

(Function) A lower alcohol is added to a pigment ink containing a polymer dispersant and a non-volatile organic solvent, and zero is used as a penetrating agent.
．． By adding 0.5% to 1.0% by weight of an acetylene glycol penetrating agent, it appears to have excellent drying speed, light resistance, and light resistance without impairing the dispersion stability of the pigment.
Provided is an IJ ink composition that can form images with excellent water resistance and the like.

(Preferred Embodiments) Next, the present invention will be described in more detail by citing preferred embodiments.

The pigments used in the present invention are organic pigments and inorganic pigments that have been conventionally used in various coloring fields, and any conventionally known pigments can be used, such as azo-based, phthalocyanine-based, quinacridone-based, Anthraquinone series, dioxazine series, indigo/thioindigo series, perinone/
Perylene series, isoindorenone series, azomethine azo series,
Examples include carbon black, and fluorescent plastic pigments such as resin particles colored with fluorescent dyes can also be preferably used.

The proportion of the pigment used in the ink composition of the present invention may be any concentration as long as it provides sufficient coloring density to the recorded object. % is preferred.

Furthermore, the polymer dispersant used in the present invention has the functions of both a dispersant and a binder, and improves the dispersion stability of pigment particles dispersed in the ink, and improves the dispersion stability of pigment particles adhered to the recording object. It has the effect of adhering particles.

Such polymer dispersants can be broadly divided into condensation polymers and addition polymers based on their structure. Any existing ones can be used, and condensation polymers are preferable, for example, special polymers. There is a polyester dispersant described in JP-A-60-26070, and as an addition polymerization dispersant, α.

Examples include addition polymers of monomers having a β-ethylenically unsaturated group.

Particularly preferred are addition polymer based dispersants, which are obtained by copolymerization of a heptamer forming the lipophilic part and a monomer forming the hydrophilic part.

The above addition-polymerizable polymer dispersant can be prepared by mixing hydrophilic and lipophilic monomers in appropriate proportions and using any conventional mixed polymerization method, such as solution polymerization method, suspension polymerization method, emulsion polymerization method, etc. It can also be obtained by the polymerization method of Known additives such as polymerization regulators can also be used if necessary. As long as the polymerization medium used at this time is water or a hydrophilic solvent that can be used as an aqueous medium for ink, the polymerization liquid obtained as is can be used as an ink medium, or the polymer can be used as a solution for ink. After separating from
It can also be used after being redissolved in an appropriate medium.

The polymer dispersant obtained in this way is not particularly defined by its molecular weight, but those having a molecular weight in the range of 1.000 to 100,000 are determined by the polymer content in the solution, solution viscosity, It is preferable from the viewpoint of properties such as viscosity of an ink composition using it and quality such as fastness of recorded matter.

In the present invention, the above-mentioned polymer dispersant can be used as it is as a binder for the pigment in the ink, but the amount of the polymer dispersant alone is insufficient as a binder, and if the abrasion resistance etc. of writing materials are not sufficient, In addition to or in place of the above-mentioned dispersant, other water-soluble resins can also be added.

Examples of such water-soluble resins include acrylic resins,
Styrene-maleic anhydride resins, maleated oils, maleated polybutadiene, maleated alkyd resins, maleated petroleum resins, maleated rosin esters, alkali metals such as polyvinylpyrrolidone, ammonia, amine salts, etc. are preferred, and do not cause excessive viscosity of the ink. Use in an amount that does not increase the amount.

The amount of the above-mentioned dispersant or water-soluble resin used in an ink composition varies depending on the type of pigment and each brand, and cannot be absolutely defined, but it is approximately 3 to 100 parts by weight per 100 parts by weight of pigment. This is the percentage of

Further, the aqueous medium constituting the ink composition of the present invention is composed of water, a nonvolatile organic solvent, and a lower alcohol, and the nonvolatile organic solvent has the effect of preventing the ink from drying in the nozzle, for example, Examples include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, methyl cellosolve acetate, methyl carpitol, ethyl carpitol, butyl carpitol, glycerin, etc. These nonvolatile organic solvents are added to 100 parts by weight of water. It is preferable to use it in a ratio of 30 to 80 parts by weight.

A preferred example of the acetylene glycol penetrating agent used in the present invention is represented by the following structural formula.

(m+n is a numerical value of 3 to 30) The penetrating agent as described above needs to be used in a small amount of 0.05 to 1.0 parts by weight per 100 parts by weight of the ink composition, and the amount used is less than the above range. On the other hand, if it exceeds the above range, it will not be sufficiently compatible with the composition of the aqueous ink medium, and may separate as an oil layer or significantly reduce the dispersion stability of the pigment. There is a problem that this is not desirable.

Furthermore, in the present invention, in order to optimize the action of the above acetylene glycol derivative, lower alcohols such as methanol, ethanol, propatool, etc. are used in a ratio of 5 to 30 parts by weight per 100 parts by weight of water. is preferable. If the amount used is less than the above range, it will be difficult to fully demonstrate the effect of the penetrating agent, and if it is too large, it will have an adverse effect on pigment dispersion stability, ink viscosity, nozzle clogging prevention, etc. This is not desirable.

Furthermore, in the present invention, other conventionally known additives, such as rust preventives, antiseptic dispersants, lubricants, etc., may be added as necessary.

The IJ ink composition of the present invention comprises the above-mentioned components and formulations, and various methods can be employed for its production.

For example, the above-mentioned components may be blended and mixed and ground using a conventionally known fractionator such as a ball mill, homomixer, sand grinder, speed line mill, or roll mill.

(Effects) According to the present invention as described above, a lower alcohol is added to a pigment ink containing a polymer dispersant and a nonvolatile organic solvent, and 0.05% to 1.0% by weight is added as a penetrating agent.
By adding an acetylene glycol penetrating agent, the IJ ink can form images with apparently excellent drying speed and excellent light resistance, water resistance, etc., without impairing the dispersion stability of the pigment. A composition is provided.

(Example) Next, the present invention will be explained in more detail by giving examples and comparative examples. In the text, parts or percentages are based on weight unless otherwise specified.

Example 1 Carbon black (product name Carbon Black #1000
, manufactured by Mitsubishi Kasei) 100 part dispersant (product name J
-62, made by Johnson Polymer, resin content 34%)
100 parts water
350 parts of the above ingredients were mixed, dispersed for 2 hours with paint conditioner (manufactured by Red Devil), and then passed through an ultracentrifuge to remove poorly dispersed coarse particles.
A black aqueous dispersion (A) was obtained.

To this dispersion A, 260 parts of ethylene glycol, 115 parts of diethylene glycol, and 115 parts of water were added.
Add 400 parts and mix and stir to obtain a pigment concentration of 7.5% and a viscosity of 3.7 cp (25°C
) and a black ink (I
) was obtained.

An IJ ink composition (11) of the present invention was obtained by adding 10 parts of ethyl alcohol and 0.4 parts of an acetylene glycol derivative (formula I) to 100 parts of the above ink (I).

Comparative Example 1 An ink composition (nl) of a comparative example was prepared by adding 15 parts of ethyl alcohol to 100 parts of ink composition (I).

Comparative Example 2 An ink composition (IV) of a comparative example was prepared by adding 0.4 parts of an acetylene glycol derivative (formula 1 above) to 100 parts of the ink composition (1).

Comparative Example 3 An ink composition (V) of a comparative example was prepared by adding 5.0 parts of an acetylene glycol derivative (formula I) to 100 parts of the ink composition (I).

Usage example 1 Dots with a diameter of approximately 1.8 to 2.6 mm were recorded using the above inks I to V on paperboard for box making (K liner paper and waterproof liner paper) using an IJ printer with a hole diameter of 300 μm. The time it took for the fingers to become clean was measured, and the results shown in Table 1 below were obtained.

Example 2 Ethylene glycol 210 parts Glycerin 110 parts Water based on the aqueous pigment dispersion (A)
380 parts butyl calpitol 10 parts were added and mixed with stirring to obtain a black ink (Vl) having a pigment concentration of 8.0%, a viscosity of 4.2 cp (at 25° C.), and a surface tension of 34 dyne/cm.

100 parts of the above ink (Vl), 5 parts of Impropatool and an acetylene glycol derivative (the above formula ■, n=10)
0.5 parts of the IJ ink composition of the present invention (■) (
A viscosity of 4.5 cp and a surface tension of 31 dyne/cm were obtained.

When IJ recording was carried out with the above inks Vl and ■ on cotton cloth before scouring in the same manner as in Example 1, it was found that the time for ink Vl to permeate into the cloth was 5 minutes, while in the case of ink ■ it was 3 minutes.
It soaked through within seconds and the color did not transfer even when rubbed.

Claims (2)

[Claims] (1) Consisting of a pigment, a polymer dispersant, an aqueous medium, and an acetylene glycol penetrating agent, the aqueous medium consisting of water, a nonvolatile organic solvent, and a lower alcohol, and the amount of the penetrating agent being 0.05 to 1 of the ink. An ink composition for IJ, characterized in that the content is within a range of % by weight. (2) The ink composition for IJ according to claim 1, wherein the penetrant is an acetylene glycol penetrant represented by the following structural formula. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (m+n is a number from 3 to 30)