Ink jet ink

Details Ink jet ink Ink jet ink

1999-01-27

2001-11-06

Jagannathan, Vasu (Department: 1714)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Processes of preparing a desired or intentional composition...

C524S590000, C524S606000, C528S045000

Reexamination Certificate

active

06313196

ABSTRACT:

This invention relates to an ink for the production of ink jet images, which are sprayed in a fine imagewise modulated jet onto a suitable recording material. The recording material consists of a transparent, semi-transparent or opaque support and an image-receiving layer located thereon.
The ink jet process is known (cf for example the chapter, “Ink jet printing” by R. W. Kenyon in
Chemistry
&
Technology of Printing
&
Imaging Systems
, editor Peter Gregory, Blackie Academic & Professional, Chapman & Hall, 1996, pp. 113-138, and the literature cited therein).
One problem associated with ink jet images is stability and smudge resistance.
It is known from EP 672 538 to add reactive components to the substrate coating compositions in order to produce water-resistant and smudge resistant ink jet prints. On subsequent irradiation of the image, these additives crosslink the coating composition, so improving the smudge resistance of the dye which has previously been transferred into these binders.
A disadvantage of this process is that a further, costly processing stage such as irradiation with UV light is required after the printing operation. Moreover, it is necessary to add further additives, for example photoinitiators, which have a tendency to yellow on storage and make the image white unattractive. Furthermore, short periods of irradiation with UV light do not bring about the desired improvement in the washing out of the prints.
The object underlying the invention is to provide an ink for ink jet printing processes which yields on various substrates without any special preparation a printed image having elevated gloss and good resistance to smudging and water and elevated light and dark stability.
It is furthermore known, in order to improve water resistance or for applications exposed to the weather, to use hydrophobic dyes which are insoluble in water, as are described, for example in
Research Disclosure
(
RD
) 30 887 (1989). Disadvantageously, these dyes must be dispersed in order to produce aqueous inks and conventional aqueous dispersions have excessively large particles and after printing exhibit an excessively wide absorption line and consequently poor colour reproduction.
It is known from DE 28 45 375 to impregnate vinyl polymer lattices with dye and to use them for the ink jet process. The low colloid stability of the impregnated latex particles and the tendency to clog the nozzles are disadvantages of this process.
A further object is to avoid this clogging of the nozzles.
It has now been found that inks consisting of a dispersion of particles of an ionically modified polymer which are loaded with dye satisfy the stated requirements.
The ionically modified polymers are preferably ionomeric polyaddition or polycondensation products.
Each 100 g of the ionomeric polyaddition or polycondensation products used according to the invention contain 4 to 180 milliequivalents, preferably 4 to 100 milliequivalents of ionic groups or groups convertible into ionic groups and optionally 1 to 20 wt. % of alkylene oxide units of the formula —CH
2
—CH
2
—O— incorporated within a polyether chain, wherein the polyether chain may be in lateral position or contained in the main chain.
Included among the ionomeric polyaddition or polycondensation products (which will be referred to below as “ionomeric products”) usable according to the invention are polyurethanes, polyesters, polyamides, polyureas, polycarbonates, polyacetals or polyethers, as well as further ionomeric products simultaneously belonging to two or more polymer types, such as for example polyester polyurethanes, polyether polyurethanes, polyester polyureas.
Ionomeric products as may be used according to the invention are known per se and are described, for example, in
Angewandte Makromolekulare Chemie
26 (1972), pp. 45-106
; Angewandte Makromolekulare Chemie
82 (1979), pp. 53 et seq.;
J. Oil. Col. Chem. Assoc
. 53 (1970), p. 363. Further descriptions of suitable ionomeric products may be found in German published patent applications (DE-A-) 26 37 690, 26 42 973, 26 51 505, 26 51 506, 26 59 617, 27 29 245, 27 30 514, 27 32 131, 27 34 576 and 28 11 148.
Ionomeric products having ionic groups are preferred. Ionomeric products particularly suitable for the process of the invention are described in DE-B2-1 472 745. These ionomeric products are based on polyurethanes which are obtained from compounds having two or more reactive hydrogen atoms and a molecular weight of 300 to 10000, polyisocyanates and optionally chain extenders having reactive hydrogen atoms. During or after the production of these polyurethanes, isocyanates still present therein are reacted with a compound having at least one active hydrogen and at least one salt-like group or group capable of salt formation. Where compounds having groups capable of salt formation are used, the resultant anionic polyurethanes are subsequently at least partially converted into the salt form in a manner known per se.
The term “salt-like group” is preferably taken to mean the following groups: —SO
3
—
, —COO
—
.
Suitable starting components for the production of the anionic polyurethanes are, for example, the compounds described below:
I. Compounds Having Active Hydrogen Atoms
These compounds are substantially linear and have a molecular weight of approx. 300 to 10000, preferably of 500 to 4000. The per se known compounds have terminal hydroxyl and/or amino groups. Polyhydroxyl compounds are preferred, such as polyesters, polyacetals, polyethers, polyamides and polyesteramides. The hydroxyl value of these compounds is approx. 370 to 10, in particular 225 to 28.
Polyethers which may be mentioned are, for example, the polymerisation products of ethylene oxide, propylene oxide, tetrahydrofuran, butylene oxide and the co- or graft polymerisation products thereof, as well as the condensation products obtained by condensation of polyhydric alcohols or mixtures thereof and the products obtained by alkoxylation of polyhydric alcohols.
Polyacetals which may be considered are, for example, the compounds which may be produced from hexanediol and formaldehyde. Suitable polyesters, polyesteramides and polyamides are the predominantly linear condensation products obtained from polybasic, saturated carboxylic acids and polyhydric, saturated alcohols, aminoalcohols, diamines and mixtures thereof.
Polyhydroxyl compounds already containing urethane or urea groups, as well as optionally modified natural polyols such as castor oil or carbohydrates may also be used.
The lyophilicity or hydrophobicity and the mechanical properties of the products of the process may, of course, be varied by using mixtures of different polyhydroxyl compounds.
II. Polyisocyanates
Suitable polyisocyanates are any aromatic and aliphatic diisocyanates, such as for example 1,5-naphthylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 4,4′-diphenyldimethylmethane diisocyanate, di- and tetraalkyldiphenylmethane diisocyanate, 4,4′-dibenzyl diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, the isomers of tolylene diisocyanate, optionally blended, preferably the aliphatic diisocyanates, 1,4-butane diisocyanate, 1,6-hexane diisocyanate, dicyclohexylmethane diisocyanate, 1,4-cyclohexane diisocyanates and isophorone diisocyanate.
III. Chain Extenders
Chain extenders having reactive hydrogen atoms include:
1. conventional glycols, such as ethylene glycol or condensation products of ethylene glycol, butanediol, 1,2-propanediol, 1,3-propanediol, neopentyl glycol, hexanediol, bishydroxymethylcyclohexane;
2. aliphatic, cycloaliphatic and aromatic diamines such as ethylenediamine, hexamethylenediamine, 1,4-cyclohexyldiamine, benzidine, diaminodiphenylmethane, the isomers of phenylenediamine, hydrazine, ammonia;
3. aminoalcohols such as ethanolamine, propanolamine, butanolamine;
4. polyfunctional amines or hydroxyl compounds such as diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, hexaethyleneptamine, glycerol, pentaerythritol, 1,3-diaminoisopropanol, 1

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