JP2000026775A - Water-based ink - Google Patents

Abstract

(57) [Problem] To provide an aqueous ink for inkjet recording which is excellent in liquid stability, high in print density and ink discharge rate, and excellent in anti-clogging properties. The aqueous ink for inkjet recording contains an aqueous dispersion of a polycondensation resin adsorbing a coloring material,
The polycondensation resin has the formula (I): (In the formula, R ¹ and R ² represent a hydrogen atom or a chain hydrocarbon group having 4 to 20 carbon atoms, except that both R ¹ and R ² are hydrogen atoms.) A water-based ink for ink-jet recording obtained by using an acid component containing at least one selected from a polyvalent carboxylic acid, an anhydride thereof and a lower alkyl ester thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an aqueous ink useful as an ink for ink-jet recording.

[0002]

2. Description of the Related Art The present inventors have disclosed Japanese Patent Application Laid-Open No. 9-183931.
And JP-A-9-183932 propose an aqueous ink containing a dispersion of a polycondensation resin containing a dye or pigment (hereinafter, referred to as a coloring material). When the concentration is increased, the liquid stability of the water-based ink is reduced, and the print density and the ink discharge rate are reduced, and the ink jet printer is clogged.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a water-based ink for ink-jet recording which is excellent in liquid stability, high in print density and ink discharge rate, and excellent in preventing clogging.

[0004]

That is, the gist of the present invention is as follows.
A water-based ink for ink-jet recording containing an aqueous dispersion of a polycondensation resin to which a coloring material is adsorbed, wherein the polycondensation resin is represented by the formula (I):

[0005]

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(Wherein, R ¹ and R ² represent a hydrogen atom or a chain hydrocarbon group having 4 to 20 carbon atoms, except that both R ¹ and R ² are hydrogen atoms). Dicarboxylic acid, its anhydride and its lower alkyl ester (hereinafter referred to as the carboxylic acid derivative, unless otherwise specified, means the dihydric carboxylic acid anhydride and its lower alkyl ester) And a water-based ink for inkjet recording obtained using an acid component containing at least one selected from the group consisting of:

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is characterized in that a polycondensation resin obtained using an acid component containing a dicarboxylic acid represented by the formula (I) or a derivative thereof is used. . Surprisingly, by using the divalent carboxylic acid represented by the formula (I) or a derivative thereof, the dispersibility and liquid stability of the coloring material are better than when using other polyvalent carboxylic acid derivatives. Thus, an excellent effect of obtaining a water-based ink for inkjet recording having high print density and high ink discharge rate and excellent clogging prevention properties is exhibited. In addition, the above-mentioned JP-A-9-183931 and JP-A-9-183932 generally disclose a divalent carboxylic acid represented by the formula (I) or a derivative thereof as one of the acid components. However, there is no disclosure or suggestion about the technical significance of using these acid components or the effects unique to the present invention.

In the formula (I), R ¹ and R ² are a hydrogen atom or a saturated or unsaturated chain hydrocarbon group having 4 to 20 carbon atoms (provided that both R ¹ and R ² are hydrogen atoms) In these, R ¹ is preferably a hydrogen atom, and R ² is preferably a saturated or unsaturated chain hydrocarbon group having 8 to 16 carbon atoms,
In particular, it is more preferably an ethylene group hydrocarbon group having 8 to 16 carbon atoms.

Specific examples of the divalent carboxylic acid represented by the formula (I) or a derivative thereof include n-dodecenylsuccinic acid,
Divalent carboxylic acids such as isododecenyl succinic acid, n-dodecyl succinic acid, isododecyl succinic acid, isooctyl succinic acid, n-octyl succinic acid, n-butyl succinic acid;
Examples of the anhydride include lower alkyl esters having 1 to 4 carbon atoms such as methyl ester and ethyl ester.

The content of the divalent carboxylic acid represented by the formula (I) or its derivative is preferably at least 3 mol%, more preferably at least 10 mol%, from the viewpoint of dispersibility of the coloring material in the acid component. From the viewpoint of emulsification, it is preferably 40 mol% or less, more preferably 30 mol% or less.
Mol% or less.

The other acid component used in the present invention is not particularly limited, and for example, the following polycarboxylic acid derivatives can be used.

The polyvalent carboxylic acid derivative is not particularly limited, but is preferably a divalent or trivalent carboxylic acid having 4 to 40 carbon atoms. For example, maleic acid, fumaric acid,
Itaconic acid, phthalic acid, isophthalic acid, terephthalic acid,
Divalent carboxylic acids such as succinic acid and dimer acid, and 1,
And trivalent carboxylic acids such as 2,4-benzenetricarboxylic acid. As used herein, “dimer acid” refers to a substance synthesized by a polymerization reaction of two molecules of unsaturated fatty acids, and is a mixture containing an acyclic dimer acid, a monocyclic dimer acid, a bicyclic dimer acid, and the like. It is commercially available as

As the lower alkyl esters of these polycarboxylic acids, alkyl esters having 1 to 4 carbon atoms are preferably used.

Polycondensation resins obtained using such an acid component include polyesters, polyamides, polyester polyamides and the like, and polyesters and polyester polyamides are preferred from the viewpoint of dispersibility of the coloring material. The polyester used in the present invention can be produced by polycondensing the acid component with, for example, a polyol component.

The polyol component is not particularly limited. Examples thereof include aliphatic polyols having 2 to 10 carbon atoms such as ethylene glycol, propylene glycol, glycerin, pentaerythritol, trimethylolpropane, sorbitol, and 1,6-hexanediol. Aromatic polyols such as bisphenol A and hydrogenated bisphenol A and their etherified polyhydroxy compounds are preferred, and preferably represented by the formula (II):

[0016]

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(Wherein R is an alkyl group having 1 to 4 carbon atoms;
A represents an alkylene group having 2 to 3 carbon atoms, x and y each represent a number of 1 or more, and the average value of x + y is 2 to 10. ) Is a polyol component containing at least 40 mol% of the diol represented by the formula (1).

Specific examples of the diol component represented by the formula (II) include polyoxypropylene (2.2) -2,2-
Bis (4-hydroxyphenyl) propane, polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane and the like can be mentioned.

The molecular weight of the obtained polyester can be appropriately adjusted by adjusting the reaction time or adding an appropriate amount of a monovalent carboxylic acid or a monohydric alcohol.

The polycondensation between the polyol component and the acid component may be carried out by a known method, for example, the polyol component and the acid component may be carried out in an inert gas atmosphere at a temperature of 180 to 250 ° C. What is necessary is just to determine by tracking a softening point (Tm), an acid value (AV), etc. which become a reference.

The molar ratio between the polyol component and the acid component may be appropriately determined depending on the value of the polyester such as AV, number average molecular weight and glass transition point (Tg). The ratio is preferably 1: 1.5 (polyol component: acid component).

At the time of this polycondensation, additives such as an esterification catalyst such as dibutyltin oxide and a polymerization inhibitor such as hydroquinone monomethyl ether can be appropriately used.

The polyamide or polyester polyamide used in the present invention can be prepared by a known method, for example, by adding an amine derivative to the acid component used for producing the polyester or the component containing the polyol and subjecting it to polycondensation. , Can be manufactured. The amine derivative is not particularly limited and includes, for example, polyamines such as ethylenediamine, hexamethylenediamine, diethylenetriamine and xylylenediamine; 6-aminocaproic acid, δ
Aminocarboxylic acids such as aminocaprylic acid and ε-caprolactam; and aminoalcohols such as propanolamine.

The molar ratio of the polyol component, the acid component and the amine derivative in the polyamide or polyester polyamide may be appropriately determined according to the value of AV, number average molecular weight, Tg, etc. of the polyamide or polyester polyamide as in the case of the polyester. You only have to decide.

In order to ensure the water resistance and liquid stability of the water-based ink, the AV of the polycondensation resin is preferably 3 mgKOH / g or more, more preferably 10 mgKOH / g.
It is preferably at most 100 mgKOH / g, more preferably at most 70 mgKOH / g. JIS K 0070 of the resin
Is preferably 1 to 30 mg.
KOH / g. The resin preferably has an amine value based on ASTM D2073 of 5 mgKOH / g or less. The resin has a Tg (measured by a differential scanning calorimeter) of 20 to 100 ° C.
Tm (measured by flow tester method) is 70 to 150 ° C
And the number average molecular weight (value converted into polystyrene by the GPC method) is preferably 1,000 to 50,000.

The polycondensation resin used in the present invention must be at least partially neutralized. For example, a neutralizing agent can be added to a solution of the resin to obtain a neutralized product. .

The neutralizing agent is not particularly limited as long as it can ionize the acid group or amino group of the polycondensation resin, and preferred examples thereof include alkali metals and alkaline earth metals for the acid group of the resin. Hydroxides such as metals and various amines; sulfuric acid,
Examples thereof include inorganic acids such as hydrochloric acid, and organic acids such as acetic acid and propionic acid. The used amount may be, for example, about 0.8 to 1.2 equivalent ratio to the acid group or amino group in the resin, respectively.

The content of the polycondensation resin in the aqueous ink is preferably 2% by weight or more, more preferably 5% by weight or more, from the viewpoints of the water resistance of the aqueous ink, its fixability and the dispersibility of the colorant. The amount is preferably 30% by weight or less, more preferably 15% by weight or less, from the viewpoint of the liquid stability of the aqueous ink and the prevention of clogging.

The polycondensation resin adsorbs a coloring material. In the present specification, "the color material is adsorbed"
The expression means either or both a state in which a coloring material is sealed in the resin fine particles and a state in which the coloring material is adsorbed on the surface of the fine particles. It is not necessary that all the coloring materials incorporated in the water-based ink of the present invention be encapsulated or adsorbed in the polycondensation resin fine particles, and the coloring materials are dispersed in the dispersion liquid as long as the effects of the present invention are not impaired. May be.

The coloring material is not particularly limited as long as it is almost insoluble or hardly soluble in water. Examples of the coloring material include dyes and pigments such as oil-soluble dyes and disperse dyes. Oil-soluble dyes and disperse dyes are preferred from the viewpoint of adsorption to polycondensation resins.

The oil-soluble dye is not limited to the following, but preferred specific examples are CI Solvent Black Series; CI Solvent Yellow Series; CI Solvent Red Series; CI Solvent Bio Red Series; CI Solvent Blue Series. CI Solvent Green Series; and CI Solvent Orange Series.

Examples of the disperse dye include, but are not limited to, CI Disperse Yellow Series; CI Disperse Orange Series; CI Disperse Red Series; CI Disperse Bio Red Series; CI Disperse Blue Series; And CI
The Disperse Green Series.

The dye is preferably dissolved in an organic solvent in an amount of 20 g / 1 or more in order to be efficiently adsorbed to the polycondensation resin at the time of phase inversion emulsification described below.
It is more preferable to dissolve g / 1. As the organic solvent used in the present invention, a ketone solvent having 3 to 8 carbon atoms such as acetone, methyl ethyl ketone and diethyl ketone, and an ether solvent having 4 to 8 carbon atoms such as tetrahydrofuran (THF) are preferable. , Methyl ethyl ketone and THF are more preferred.

The pigment is not particularly limited, and known pigments such as azo pigments, phthalocyanine pigments, anthraquinone pigments and carbon black pigments can be used.

The content of the coloring material in the aqueous ink is preferably 1% by weight or more in order to obtain a sufficient printing density.
The content is more preferably 1.5% by weight or more, and from the viewpoint of liquid stability of the aqueous ink, preferably 30% by weight or less, more preferably 25% by weight or less.

The water-based ink of the present invention contains a water-soluble substance, preferably N-methylglycine, trimethylglycine, urea, carbon number 2 in order to further improve the ink ejection property, the clogging prevention property and the liquid stability. It is desirable to add about 3 to 30% by weight of the polyhydric hydroxy compound of (1) to (4).

Next, a method for producing the water-based ink of the present invention will be described. The aqueous ink of the present invention is produced by so-called phase inversion emulsification. As a preferred production method, a polycondensation resin is added to an organic solvent together with a coloring material, a neutralizing agent and water are added to ionize a carboxyl group or an amino group in the polycondensation resin, and if necessary, the water-soluble substance is used. , The organic solvent is distilled off and the phase is changed to an aqueous phase. Phase inversion is
It may occur when water is added, but from the viewpoint of obtaining a stable dispersion, it is more preferable that it occurs during the distillation of the organic solvent.

Specifically, 5 to 50 parts by weight of a polycondensation resin and 0.1 to 50 parts by weight of a colorant are dissolved in 100 parts by weight of an organic solvent, and 100 to 300 parts by weight of a neutralizing agent and water are dissolved. If necessary, the water-soluble substance is further added. In this case, known surfactants such as various anions and nonionics, especially β-naphthalenesulfonic acid formalin condensate, are added to water, so that the average particle diameter of the fine particles of the polycondensation resin can be reduced. preferable.

Next, the organic solvent is distilled off at 30 to 70 ° C. under reduced pressure, and its content is adjusted to preferably 5% by weight or less, more preferably 3% by weight or less. Further, it is more preferable to adjust the pH of the obtained processing solution to be 5 to 12.

The particle size of the fine particles of the polycondensation resin is determined from the viewpoints of suppression of bleeding on the printing surface of the aqueous ink and liquid stability.
Preferably it is 0.1 nm to 500 nm, more preferably 5 nm to 300 nm. The particle size can be appropriately adjusted by changing, for example, the molecular weight, AV, degree of neutralization, and conditions of phase inversion emulsification of the resin.

In addition to the above-mentioned components, the water-based ink of the present invention contains various conventionally known additives such as acetylenol E
H (manufactured by Kawaken Fine Chemical Co., Ltd.), UV absorbers such as benzotriazole and benzophenone, fungicides such as chloromethylphenol, EDTA
And the like, and an oxygen absorbent such as a sulfite.

The water-based ink of the present invention obtained by such a method is particularly useful as a water-based ink for ink-jet recording, but can also be used as an ink for general writing implements such as fountain pens, ball-point pens, and felt-tip pens. is there.

[0043]

EXAMPLES Production Example 1 Polyoxypropylene (2.2) -2,2-bis (4-
Hydroxyphenyl) propane (1035 g), terephthalic acid (324 g), isododecenyl succinic anhydride (201 g), and dibutyltin oxide (2.6 g) were reacted with stirring at 230 ° C. for 12 hours under a nitrogen stream, and then 144 g of trimellitic anhydride was added. Was reached when the reaction reached 36 mg KOH / g. The obtained polyester was a pale yellow solid, OHV was 5.1 mgKOH / g, Tg was 68 ° C, Tm was 111 ° C, and number average molecular weight was 2780. The AV, OHV, amine value, Tg,
Tm and number average molecular weight were measured by the above-mentioned methods.

Example 1 150 g of the polyester obtained in Production Example 1 and an oil-soluble dye (OIL BLACK 860, manufactured by Orient Chemical; the same applies hereinafter)
After dissolving 00 g in 500 g of THF, 17.2 g of dimethylethanolamine and 1.3 g of sodium hydroxide were dissolved.
Was added. Further, 960 g of ion-exchanged water, 3 g of β-naphthalenesulfonic acid formalin condensate (manufactured by Kao Corporation, Demol N, the same applies hereinafter), a mixed aqueous solution of 50 g of N-methylglycine and 20 g of glycerin were added dropwise, and the mixture was stirred. At 40 ° C., THF was distilled off to obtain a polyester dispersion (average particle size: 31 nm, solid content: 20% by weight).
After filtering the obtained dispersion through a 1000 nm filter,
A water-based ink for inkjet recording having the following composition was used. 6. polyester dispersion 60.0 g, ethylene glycol
0 g, glycerin 10.0 g, ion-exchanged water 20.0
g, sodium dioctyl sulfosuccinate 0.5 g, acetylenol EH 0.5 g.

Production Example 2 Polyoxypropylene (2.2) -2,2-bis (4-
While stirring 1060 g of hydroxyphenyl) propane and 2.5 g of dibutyltin oxide at 230 ° C. under a nitrogen stream,
n-dodecenyl succinic anhydride 100 g, terephthalic acid 3
64 g, 52 g of dimer acid and 20 g of 6-amino-n-caproic acid were added in this order and reacted for 13 hours. Then, 145 g of trimellitic anhydride was added, and 55.5 mg of AV was added.
When KOH / g was reached, the reaction was terminated. The obtained polyester polyamide is a pale yellow solid and has an OHV of 7.
4 mg KOH / g, amine value 0.1 mg KOH / g, Tg 61.
At 3 ° C, Tm was 107.0 ° C, and the number average molecular weight was 2,330.

Example 2 Using the polyester polyamide obtained in Production Example 2, except that the amounts of dimethylethanolamine and sodium hydroxide used were 15.9 g and 1.8 g, respectively.
A dispersion of polyester polyamide (average particle size: 25 nm, solid content: 20% by weight) was obtained in the same manner as described above. The obtained dispersion was filtered through a 1000-nm filter to obtain a water-based ink for inkjet recording having the following composition. 60.0 g of polyester polyamide dispersion, 10.0 g of N-methylglycine, 2.5 g of glycerin, 2.0 g of sodium octyl sulfate, 25.0 g of ion-exchanged water, and 0.5 g of acetylenol EH.

Production Example 3 Polyoxypropylene (2.2) -2,2-bis (4-
1035 g of hydroxyphenyl) propane, fumaric acid 2
Except for using 78 g, 115 g of trimellitic anhydride, 0.7 g of hydroquinone and 2.1 g of dibutyltin oxide,
Polyester (AV: 30.0 mg) in the same manner as in Production Example 1.
KOH / g, appearance: pale yellow solid, OHV: 36.4 mg KOH /
g, Tg: 52.9 ° C., Tm: 88.8 ° C., number average molecular weight: 2900).

Comparative Example 1 A dispersion was prepared in the same manner as in Example 1 except that the polyester obtained in Production Example 3 was used. However, a precipitate was formed in the dispersion. Thus, a dispersion (average particle size: 92 nm, solid content: 9% by weight) was obtained. A water-based ink for inkjet recording was obtained in the same manner as in Example 1 except that this dispersion was used.

Production Example 4 Polyoxypropylene (2.2) -2,2-bis (4-
(Hydroxyphenyl) propane 1035 g, terephthalic acid 324 g, dimer acid 432 g, dibutyltin oxide
Polyester (AV: 43.2 mg KO) in the same manner as in Production Example 1 except that 9 g and 144 g of trimellitic anhydride were used.
H / g, appearance: pale yellow solid, OHV: 23.4 mgKOH / g
, Tg: 40.7 ° C, Tm: 88.9 ° C, number average molecular weight: 3100).

Comparative Example 2 A dispersion was prepared in the same manner as in Example 1 except that the polyester obtained in Production Example 4 was used, to obtain a water-based ink for inkjet recording.

Using the ink jet recording water-based inks obtained in Examples 1 and 2 and Comparative Examples 1 and 2, a commercially available Canon color bubble jet printer (model number BJC-430) was used.
J, the same applies hereinafter), and the following liquid stability, print density, ink discharge rate, and clogging prevention properties were evaluated. The results are summarized in Table 1.

[Liquid stability] <Change in particle size and change in absorbance>
Particle size distribution is measured using a COULTER ELECTRONIC
S Co .: Product name: COULTER MODEL N4), and the change in absorbance was evaluated at a wavelength of 600 nm by diluting the ink 1000 times. Regarding the change in particle size, in the table, は indicates that there is no change in the particle size distribution, 粒径 indicates that there is a change in the particle size distribution, but it is still a monodispersed system, and △ indicates that the particle size distribution changes significantly. And 2
It is a polydisperse system having a distribution equal to or higher than the peak, and x indicates that a coagulated precipitate has occurred at the liquid bottom. Regarding the change in absorbance, ◎ in the table indicates that the change in absorbance is less than 0.05, ○ indicates less than 0.10, Δ indicates less than 0.20, and x indicates 0.20 or more.

<Print Density> After the solid print was naturally dried in a room for 24 hours, the optical density was measured with a Macbeth densitometer RD918 (manufactured by Macbeth).

<Ink Discharge Rate> The ink discharge rate was calculated from the weight change of the ink cartridge before and after solid printing.
Note that the ink ejection amount when using the genuine ink attached to the printer is assumed to be 100.

<Clogging Prevention> After printing continuously for 10 minutes, the sample was left for 2 weeks in an environment of 35 ° C. and 25% relative humidity (RH) without capping after printing. Next, printing was performed, and the number of times of clogging recovery operation (cleaning) required until printing equivalent to that before standing was obtained was examined. In the table, ◎ indicates no return operation,
○ indicates 1 to 2 times, Δ indicates 3 to 5 times, and X indicates 6 or more times.

[0056]

[Table 1]

From the results shown in Table 1, Examples 1 and 2
The water-based ink for ink-jet recording obtained in Comparative Example 1 has almost no change in particle diameter and absorbance, is excellent in liquid stability, is excellent in print density and ink discharge rate, as compared with the water-based ink for ink-jet recording obtained in Comparative Examples 1 and 2. It can be seen that the material has high anti-clogging properties.

[0058]

According to the present invention, it is possible to obtain a water-based ink for ink jet recording which is excellent in liquid stability, high in print density and ink discharge rate, and excellent in clogging prevention.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H086 BA53 4J029 AA03 AB07 AC02 AD01 AD02 AD03 AD06 AD07 AE12 CA04 CA09 HB01 HB03A HB06 4J038 DD051 DD061 DD081 DD091 DD191 DH021 DH031 GA06 GA09 HA026 HA096 HA176 HA186 HAB18 KA09 MA10 NA23 NA25 4J039 AE06 AE08 AE13 BE01 BE07 BE08 BE30 CA03 CA06 EA41 EA44 EA46 GA24

Claims (4)

[Claims] 1. A water-based ink for ink-jet recording containing an aqueous dispersion of a polycondensation resin adsorbing a coloring material, wherein the polycondensation resin has the formula (I): (In the formula, R ¹ and R ² represent a hydrogen atom or a chain hydrocarbon group having 4 to 20 carbon atoms, except that both R ¹ and R ² are hydrogen atoms.) A water-based ink for ink-jet recording obtained by using an acid component containing at least one selected from a polyvalent carboxylic acid, an anhydride thereof and a lower alkyl ester thereof. 2. In the formula (I), R ¹ is a hydrogen atom,
^2. The aqueous ink according to claim 1, wherein ² is a chain hydrocarbon group having 8 to 16 carbon atoms. 3. The content of the dicarboxylic acid represented by the formula (I) or a derivative thereof is 3 to 40 mol% in the acid component.
The aqueous ink according to claim 1 or 2, wherein 4. The aqueous ink according to claim 1, wherein the polycondensation resin is a polyester or a polyester polyamide.