JPH10158563A - Aqueous pigment-dispersed ink composition for ink jet printing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an aqueous pigment-dispersed ink composition for ink jet printing excellent in dryirug properties, printed letter quality such as bleeding and ejecting stability from a nozzle. SOLUTION: This aqueous pigment-dispersed ink composition for ink jet printing consists essentially of a pigment, an aqueous resin, a basic compound and an aqueous medium. An acrylic copolymer resin containing fluorine obtained by polymerizing an monoethylenic a, β-unsaturated carboxylic acid monomer, 3-30wt.% acrylic monomer containing the fluorine based on the whole monomer components, and optionally other copolymerizable and radically polymerizable monomers is used as a part of the aqueous resin. The aqueous pigment-dispersed ink composition for ink jet printing includes 0.01-1.5wt.% acrylic copolymer resin containing the fluorine and 0.1-10wt.% other aqueous resins.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording head having excellent drying characteristics and excellent bleeding, sharpness of contour, sharpness and the like when recording is performed by discharging ink from a discharge orifice of a recording head and flying as droplets. The present invention relates to an aqueous pigment-dispersed ink composition for ink-jet recording having excellent printing quality and nozzle ejection stability.

[0002]

2. Description of the Related Art An image is formed by an ink jet method in which ink is ejected by using an electrostatic suction method, a pneumatic feeding method, a method utilizing pressure during heating and foaming, a method utilizing electric deformation of a piezoelectric element, or the like. Ink used at that time has conventionally been required to satisfy the following contradictory characteristics.

[0003] The characteristics thereof include, when an image is formed on a recording paper, irregular ink flow along the fibers of the recording paper and irregular ink permeation between fibers (hereinafter referred to as bleeding). That no drying occurs when an image is formed on recording paper, that the recording head does not clog in long-term storage, that is, that the ejection stability is good,
Good water resistance of the image.

[0004] In particular, in recent years, there has been a demand for an ink that has a fast drying property, has no bleeding, and has good ejection stability.

In a pigment-based ink for ink jet recording, a pigment dispersing resin is used to disperse the pigment.
For example, Japanese Unexamined Patent Publication No. 56-14763 discloses a styrene-acrylic acid-butyl acrylate copolymer.
In JP-A-6-147867, an aqueous resin such as a styrene-acrylic resin is used, and in JP-A-56-157468, an aqueous resin such as a styrene-maleic acid copolymer is used. It is difficult to simultaneously satisfy conflicting properties such as print quality, drying properties, and ejection stability, and inks that simultaneously satisfy these properties have not been realized by conventional techniques.

[0006]

SUMMARY OF THE INVENTION The present invention solves these problems, and provides an aqueous pigment-dispersed ink composition for ink jet recording which is excellent in drying property, printing quality such as bleeding, and nozzle ejection stability. The task is to do so.

[0007]

Means for Solving the Problems The present invention provides (1) a pigment,
In an aqueous pigment-dispersed ink composition for ink jet recording mainly composed of an aqueous resin, a basic compound, and an aqueous medium, α, β-monoethylenically unsaturated carboxylic acid monomer and fluorine are used as a part of the aqueous resin. Acrylic monomer containing, and if necessary, a fluorine-containing acrylic copolymer having an acid value of 10 to 300 obtained by polymerizing a monomer component composed of another copolymerizable radically polymerizable monomer The present invention relates to a water-based pigment-dispersed ink composition for inkjet recording, characterized by using a resin.

Further, the present invention provides (2) that the content of the fluorine-containing acrylic monomer in the fluorine-containing acrylic copolymer resin is 3 to 30% by weight based on all monomer components. The present invention relates to the aqueous pigment-dispersed ink composition for ink jet recording according to the above (1).

Further, according to the present invention, (3) the fluorine-containing acrylic copolymer resin and the other aqueous resin are each added to the aqueous pigment-dispersed ink composition for inkjet recording in an amount of 0.01 to 1.5% by weight. The aqueous pigment-dispersed ink composition for inkjet recording as described in the above item (1) or (2), wherein the content is 0.1 to 10% by weight.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION As a result of repeated studies to solve the above problems, the present inventors have found that a fluorine-containing acrylic copolymer resin is used as a part of the aqueous resin of the aqueous pigment-dispersed ink composition for ink jet recording. By using this, it was found that an aqueous pigment-dispersed ink composition for inkjet recording having excellent drying properties, and excellent print quality such as bleeding and nozzle ejection stability was obtained, and the present invention was completed. is there.

Hereinafter, the present invention will be described in more detail.

First, the aqueous resin used in the aqueous pigment-dispersed ink composition for inkjet recording of the present invention will be described.

The aqueous resin used in the aqueous pigment-dispersed ink composition for ink-jet recording of the present invention includes a fluorine-containing acrylic copolymer resin and an aqueous resin conventionally used in an aqueous pigment-dispersed ink composition for ink-jet recording. Can be used.

First, as the fluorine-containing acrylic copolymer resin, there are α, β-monoethylenically unsaturated carboxylic acid monomer, fluorine-containing acrylic monomer and, if necessary, other copolymers. An acid value of 10 to 30 obtained by copolymerizing a monomer component comprising a possible radically polymerizable monomer
A fluorine-containing acrylic copolymer resin of 0 can be used.

Here, α, β-monoethylenically unsaturated carboxylic acid monomers include (meth) acrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic anhydride, maleic acid, maleic acid monoester and the like. Can be exemplified. These can be used alone or in combination.

The fluorine-containing acrylic monomer includes one or more fluoroalkyl (meth) acrylates represented by the following general formula (1) or (2).

[0017]

Embedded image

(Wherein, R ¹ is a hydrogen atom or a methyl group, R ² is a perfluoroalkyl group having 1 to 12 carbon atoms,
m is an integer of 0 to 4, n is an integer of 1 to 12, m + n is 2
An integer of 15, p is an integer of 1 to 4, and the sum of p and the carbon number of the perfluoroalkyl group is an integer of 2 to 15).

Examples of the fluoroalkyl (meth) acrylate include 2,2,2-trifluoroethyl (meth)
Acrylate, 2,2,3,3-tetrafluoropropyl (meth) acrylate, 1,1,2,2,3,3-hexafluoropropyl (meth) acrylate, 3,3
4,4,4-pentafluorobutyl (meth) acrylate, 2,2,3,3,4,4,5,5-octafluoropentyl (meth) acrylate, perfluorooctylethyl (meth) acrylate, and the like. Can be.

The fluorine-containing acrylic monomer is desirably used in an amount of 3 to 30% by weight based on all monomer components. When the content of the fluorine-containing acrylic monomer is less than 3% by weight, no effect is exhibited on the drying property,
If it is more than 0% by weight, a problem arises in that the polymerization reactivity between the fluorine-containing acrylic monomer and other monomers is reduced.

Further, other copolymerizable radical polymerizable monomers include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, and the like.
Examples thereof include (meth) acrylates such as 2-ethylhexyl (meth) acrylate and octyl methacrylate, styrene, methylstyrene, vinyltoluene, and vinyl acetate.

The acid value of the fluorine-containing acrylic copolymer resin obtained by polymerizing the above monomer component is 10 to 300 (m
g / KOH, the same applies hereinafter), preferably 30 to 100.

When the acid value of the fluorine-containing acrylic copolymer resin is less than the above range, it is difficult to make the resin aqueous, and when the acid value exceeds the above range, the water resistance of the obtained image decreases.

The amount of the fluorine-containing acrylic copolymer resin to be used is preferably 0.01 to 1% based on the total amount of the aqueous pigment-dispersed ink composition for ink jet recording.
The amount is 5% by weight, more preferably 0.1 to 1.2% by weight. When the amount is less than this range, the drying property is slow, and when the amount is more than this range, printability such as bleeding is reduced. .

The other aqueous resin used in the aqueous pigment-dispersed ink composition for ink-jet recording of the present invention is described in the applicant's application having a weight average molecular weight in the range of 5,000 to 30,000. Related Japanese Patent Application Hei 7-25523
Aqueous resin described in No. 3, for example, alkyl acrylate- (meth) acrylic acid copolymer, styrene-acrylic acid copolymer, styrene-acrylic acid-alkyl acrylate copolymer, styrene-maleic Acid copolymers, styrene-maleic acid-alkyl acrylate copolymers, styrene-methacrylic acid copolymers, styrene-methacrylic acid-acrylic acid alkyl ester copolymers, styrene-maleic acid half ester copolymers, and the like. No.

The other aqueous resin is used in an amount of 0.1 to 1 based on the aqueous pigment-dispersed ink composition for ink jet recording.
It is desirably contained in an amount of 0% by weight, preferably 0.1 to 5% by weight.

As the basic compound used in the aqueous pigment-dispersed ink composition for ink jet recording of the present invention, a basic compound which dissolves a generally used aqueous resin in an aqueous medium can be used.

Specifically, alkylamines such as butylamine and triethylamine, alkanolamines such as monoethanolamine, diethanolamine and triethanolamine, morpholine, aqueous ammonia and sodium hydroxide can be used. Above all, from the viewpoint of reducing clogging of the discharge orifice, it is preferable to use a fast-volatile basic compound and a slow-volatile basic compound in combination.

As the pigment used in the aqueous pigment-dispersed ink composition for ink jet recording of the present invention, known inorganic and organic pigments that can be dispersed in an aqueous medium can be used. Are preferred.

The inorganic pigments usable herein include titanium oxide, red iron oxide, antimony red, cadmium red, cadmium yellow, cobalt blue, navy blue, ultramarine, carbon black, graphite and the like. Organic pigments include soluble azo pigments, insoluble Examples include azo pigments, azo lake pigments, condensed azo pigments, copper phthalocyanine pigments, condensed polycyclic pigments, and the like.

The amount of the pigment used is 1 to 1 with respect to the entire aqueous pigment-dispersed ink composition for ink jet recording.
The amount is about 30% by weight, preferably 2 to 10% by weight. When the amount is less than this range, the color density is reduced. On the other hand, when the amount is more than this range, use becomes difficult from the viewpoint of ink viscosity and fluidity.

As the aqueous medium used in the aqueous pigment-dispersed ink composition for ink jet recording of the present invention, water or a mixture of water and a water-miscible solvent, which has been generally used in the art, can be used. Can be used.

Here, examples of the water-miscible solvent include lower alcohols, polyhydric alcohols and derivatives thereof, and nitrogen-containing cyclic compounds.

Specifically, lower alcohols such as methanol, ethanol, normal propanol and isopropanol, ethylene glycol, propylene glycol,
Polyethylenes such as diethylene glycol, dipropylene glycol, glycerin, polyglycerin, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monoethyl ether, propylene glycol monomethyl ether,
Polyhydric alcohol derivatives such as propylene glycol acetate, diethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, nitrogen-containing cyclic compounds such as N-methylpyrrolidone and N-ethylpyrrolidone, and ethylene oxide adducts of polyglycerin can be used.

Of these, polyglycerin ethylene oxide adduct is preferred from the viewpoint of ejection stability. In particular, those obtained by adding 5 to 90 mol of ethylene oxide to 1 mol of polyglycerin are preferable.

As a water-miscible solvent, acetone, ethyl acetate and the like are not preferred because they may damage the printing apparatus.

The aqueous pigment-dispersed ink composition for ink-jet recording of the present invention may further contain various additives such as a surfactant, a pigment dispersant, a viscosity modifier and an antifoaming agent, if necessary. it can.

As a method for producing an aqueous pigment-dispersed ink composition for ink-jet recording using the above components, first, a pigment, an aqueous resin, a basic compound, an aqueous medium, and if necessary, a surfactant and a pigment Agent, viscosity modifier, antifoaming agent, etc., and then mixed with various meat machines, for example, a bead mill,
Ball mill, sand mill, attritor, roll mill,
An agitator, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, an ultra-high pressure homogenizer, a pearl mill, and the like, are ground and further mixed with the remaining material, and a fluorine-containing acrylic copolymer resin according to the present invention. Available. It should be noted that the fluorine-containing acrylic copolymer resin according to the present invention can also be mixed before kneading.

In the present invention, a method for obtaining a pigment dispersion having a desired particle size distribution includes reducing the size of the pulverized media of the disperser, increasing the filling rate of the pulverized media, increasing the processing time, and discharging speed. For example, a method of slowing down the particle size, classifying with a filter or a centrifuge after pulverization, or the like is used.

[0040]

EXAMPLES The present invention will now be described specifically with reference to examples, but the present invention is not limited to these examples.

<Preparation of Aqueous Pigment Dispersion for Inkjet Recording> 20 mol of ethylene oxide was added to ion-exchanged water, aqueous ammonia, carbon black (Prentex 35, manufactured by Columbia Carbon Co.), and polyglycerin (degree of polymerization: 4). Compound, diethylene glycol, acrylic copolymer resin (monomer composition: methacrylic acid /
15. Methyl methacrylate / stearyl acrylate = 15.
3 / 74.7 / 10 weight ratio, acid value 68, weight average molecular weight 11,000), a compound obtained by adding 14 mol of ethylene oxide to p-hydroxybiphenyl (pigment dispersant), and premixing for 1 hour After that, kneading was performed using a circulation type bead mill, and ion-exchanged water was further added to obtain an aqueous pigment dispersion for inkjet recording.

Table 1 shows the composition of the aqueous pigment dispersion for ink jet recording.

[0043]

[Table 1]

<Preparation of Aqueous Pigment-Dispersed Ink Composition for Inkjet Recording> Examples 1-3 and Comparative Example A fluorine-containing acrylic copolymer resin (EFKA-L, manufactured by EFKA) was added to the aqueous pigment dispersion for inkjet recording.
P7070, an acid value of 55, and a solid content of 60% by weight) were added in the proportions shown in Table 2 to prepare an aqueous pigment-dispersed ink composition for ink jet recording.
The clogging of the discharge orifice was evaluated by the following method.
The results are shown in Table 2 and below.

<Drying property> On-demand printing of the aqueous pigment-dispersed ink compositions for ink jet recording of Examples 1 to 3 and Comparative Example by applying thermal energy to the ink in the recording head to generate droplets and perform recording. PPC paper (Kokuyo Co., Ltd.)
And neutral paper, hereinafter referred to as PPC paper A), and PPC paper (manufactured by Matsushita Electric Industrial Co., Ltd., acid paper, hereinafter referred to as PPC paper B). The time was measured and evaluated.

<Bleeding> Printing was performed in the same manner as for the drying property, and the bleeding was visually determined. A: no bleeding was observed with the naked eye; B: very bleeding was observed with the naked eye; C: bleeding was observed but characters were recognized; and D was bleeding and characters were not recognized.

<Clogging of Discharge Orifice> The head of the recording apparatus used for the evaluation of dryness was filled with the aqueous pigment-dispersed ink compositions for ink jet recording of Examples 1 to 3 and Comparative Example, and the cap was kept at 20.degree. After being allowed to stand for 3 days under the ambient temperature of 3, the clogging of the discharge orifice was evaluated under conditions that enabled printing. In each case of the aqueous pigment-dispersed ink compositions for ink jet recording of Examples and Comparative Examples, printing was possible with the number of times of cleaning of the ejection orifice being 0 to 2 times, which was good.

[0048]

[Table 2]

[0049]

As described above, the aqueous pigment-dispersed ink composition for ink jet recording of the present invention uses a fluorine-containing acrylic copolymer resin as a part of the aqueous resin. Thereby, the drying property can be improved without lowering the printing quality such as the ejection stability and the bleeding.

Claims (3)

[Claims] Claims: 1. In an aqueous pigment-dispersed ink composition for inkjet recording mainly composed of a pigment, an aqueous resin, a basic compound, and an aqueous medium, α, β-monoethylenically unsaturated carboxylic acid is used as a part of the aqueous resin. An acid value of 10 to 300 obtained by polymerizing an acid monomer, a fluorine-containing acrylic monomer, and a monomer component composed of other copolymerizable radically polymerizable monomers as necessary. An aqueous pigment-dispersed ink composition for inkjet recording, characterized by using a fluorine-containing acrylic copolymer resin. 2. The fluorine-containing acrylic copolymer resin according to claim 2, wherein the content of the fluorine-containing acrylic monomer is 3 to 30% by weight based on all monomer components. 2. The aqueous pigment-dispersed ink composition for inkjet recording according to item 1. 3. The fluorine-containing acrylic copolymer resin and the other aqueous resin are added in an amount of 0.01 to 1.5% by weight and 0.1 to 10% by weight, respectively, in the aqueous pigment-dispersed ink composition for inkjet recording. The aqueous pigment-dispersed ink composition for ink-jet recording according to claim 1 or 2, which is contained by weight.