Patent Application
20080182080
The present invention relates to an aqueous dispersion comprising a pigment (B) at least partially enveloped by at least one radiation-curable polyurethane (A), at least one radiation-curable polyurethane (A) being obtainable by reaction of
The present invention further relates to at least partially enveloped pigments produced by dispersing at least one pigment (B) and at least one radiation-curable polyurethane (A), said radiation-curable polyurethane (A) being obtainable by reaction of
The present invention further relates to the production of at least partially enveloped pigments according to the present invention and of aqueous dispersions according to the present invention and also to their use.
It is frequently necessary to disperse pigments in a liquid and, in particular, aqueous medium in order that they may be further processed to form, for example, recording fluids and, in particular, inks. Particularly strict requirements are placed in this connection on inks used in the ink jet process (such as thermal ink jet, piezo ink jet, continuous ink jet, valve jet, transfer printing processes). They have to have a viscosity and surface tension suitable for printing, they have to be stable in storage, i.e., they should not coagulate or flocculate, and they must not lead to cloggage of printer nozzles, which can be problematical particularly in the case of inks comprising dispersed, i.e., undissolved, colorant particles. Stability in storage further requires of these recording fluids and in particular inks that dispersed colorant particles do not sediment. Furthermore, in the case of continuous ink jet the inks shall be stable to the addition of conducting salts and be free of any tendency to floc out with an increase in the ion content. In addition, the prints obtained have to meet colorists' requirements, i.e., exhibit brilliance and depth of shade, and have good fastnesses, for example dry rub fastness, light fastness, water fastness and wet rub fastness, if appropriate after after treatment such as fixation for example, and good drying.
To ensure particularly good fastnesses such as for example dry rub fastness, wet rub fastness and wash fastness for printed substrates, prints can be fixed through so-called radiation curing. So-called radiation-curable inks may be employed for this purpose, see for example U.S. Pat. No. 5,623,001 and EP 0 993 495. Radiation-curable ink jet inks typically comprise a material which can be cured by subjecting it to actinic radiation. In addition, a photoinitiator may be included in radiation-curable ink jet inks.
There is a problem, however, in that in some cases the degree of radiation curing is not uniform across the printed substrate. Curing is observed to be very good in some places, whereas it is poor in other areas, known as soft spots. Nonuniform curing compromises rub fastnesses in some areas. In addition, the hand of printed substrates deteriorates, which is undesirable for printed textile substrates in particular. There is thus a need for ink jet process inks which provide particularly uniform curing.
Radiation-curable di- and polyurethanes are known, for example from EP-B 1 144 476 and EP 1 118 627. The radiation-curable polyurethanes described in the previously cited references can be used for coating furniture or automobiles for example. There are numerous applications, however, for which their performance characteristics need to be improved.
The present invention therefore has for its object to provide aqueous dispersions of pigments. The present invention further has for its object to provide inks for the ink jet process which are particularly readily curable through the action of actinic radiation. The present invention further has for its object to provide processes for producing inks for the ink jet process. The present invention finally has for its object to provide printed substrates and in particular printed textile substrates having a particularly good hand and good fastnesses.
We have found that this object is achieved by aqueous dispersions defined at the beginning.
As used herein, the expressions “inks for the ink jet process” and “ink jet inks” are equivalent.
Polyurethanes shall for the purposes of the present invention be understood as meaning not just such polymers as are exclusively linked by urethane groups but in a more general sense polymers obtainable by reaction of di- or polyisocyanates with compounds comprising active hydrogen atoms. Polyurethanes for the purposes of the present invention thus may comprise urea, allophanate, biuret, carbodiimide, amide, ester, ether, uretoneimine, uretidione, isocyanurate or oxazolidine groups as well as urethane groups. As a general reference there may be cited by way of example: Kunststoffhandbuch/Saechtling, 26th edition, Carl-Hanser-Verlag, Munich 1995, pages 491 et seq. More particularly, polyurethanes for the purposes of the present invention comprise allophanate groups.
In one embodiment of the present invention, the radiation-curable polyurethane (A) is not a hyperbranched polyurethane. Hyperbranched polyurethanes are known as such and are described for example in J.M.S.—Rev. Macromol. Chem. Phys. 1997, C37(3), 555.
Aqueous dispersions according to the present invention comprise at least one pigment (B) at least partially enveloped by at least one radiation-curable polyurethane (A). In what follows, “pigment at least partially enveloped by at least one radiation-curable polyurethane” is to be understood as meaning such a pigment in particulate form whose outer surface is wholly or partly covered by radiation-curable polyurethane. Mixtures of pigment in particulate form in each of which a certain percentage of the pigmentary particles is not enveloped by radiation-curable polyurethane and in each of which the outer surface of the other pigmentary particles is wholly or partly covered by radiation-curable polyurethane likewise come within the definition of “pigment at least partially enveloped by at least one radiation-curable polyurethane”.
In one embodiment of the present invention, pigment at least partially enveloped by at least one radiation-curable polyurethane has at least 10%, preferably at least 20% or more preferably at least 30% of its outer surface covered by radiation-curable polyurethane.
The degree of envelopment can be determined for example by measuring the zeta potential, through microscopic methods such as for example optical microscopy or methods of electron microscopy (TEM, cryo-TEM, SEM) and, quite specifically, with the aid of the freeze fracture preparation technique, NMR spectroscopy or photoelectron spectroscopy on dried at least partially enveloped pigment.
At least partially to be enveloped pigments (B) are obtained in the realm of the present invention by at least partial envelopment of virtually water-insoluble, finely divided, organic or inorganic colorants as per the definition in German standard specification DIN 55944. Aqueous dispersions according to the present invention are preferably produced from organic pigments, which comprises carbon black. Examples of particularly suitable pigments (B) will now be identified.
Iron oxide brown, mixed brown, spinell and corundum phases (C.I. Pigment Brown 24, 29 and 31), chromium orange;
Iron oxide yellow (C.I. Pigment Yellow 42); nickel titanium yellow (C.I. Pigment Yellow 53; C.I. Pigment Yellow 157 and 164); chromium titanium yellow; cadmium sulfide and cadmium zinc sulfide (C.I. Pigment Yellow 37 and 35); chromium yellow (C.I. Pigment Yellow 34), zinc yellow, alkaline earth metal chromates; Naples yellow; bismuth vanadate (C.I. Pigment Yellow 184);
Preferred pigments (B) in this context are monoazo pigments (especially laked BONS pigments, Naphthol AS pigments), disazo pigments (especially diaryl yellow pigments, bisacetoacetanilide pigments, disazopyrazolone pigments), quinacridone pigments, quinophthalone pigments, perinone pigments, phthalocyanine pigments, triaryicarbonium pigments (alkali blue pigments, laked rhodamines, dye salts with complex anions), isoindoline pigments and carbon blacks.
Examples of particularly preferred pigments (B) are specifically: carbon black, C.I. Pigment Yellow 138, C.I. Pigment Red 122 and 146, C.I. Pigment Violet 19, C.I. Pigment Blue 15:3 and 15:4, C.I. Pigment Black 7, C.I. Pigment Orange 5, 38 and 43 and C.I. Pigment Green 7.
Radiation-curable polyurethanes (A) for the purposes of the present invention are obtainable by reaction of
At least one di- or polyisocyanate (a) which comprises on average from 1 to 10 and preferably up to 5 allophanate groups and on average per molecule from 1 to 10 and preferably up to 5 C—C double bonds per molecule, average values each being based on the weight average and preferably on the number average, is a compound which is preferably prepared in the presence of a catalyst, from at least one diisocyanate (a1) with at least one compound of the general formula I
herein also referred to as compound (a2) for short, the variables being defined as follows:
Very particularly preferred compounds of the general formula I are 2-hydroxyethyl (meth)acrylate and 3-hydroxypropyl (meth)acrylate.
Radiation-curable polyurethane may be prepared in the absence or preferably in the presence of at least one catalyst.
Useful catalysts include for example all catalysts typically used in polyurethane chemistry.
Catalysts typically used in polyurethane chemistry are preferably organic amines, especially tertiary aliphatic, cycloaliphatic or aromatic amines, and Lewis-acidic organic metal compounds.
Useful Lewis-acidic organic metal compounds include for example tin compounds, for example tin(II) salts of organic carboxylic acids, examples being tin(II) acetate, tin(II) octoate, tin(II) ethylhexanoate and tin(II) laurate and the dialkyltin(IV) derivatives of organic carboxylic acids, examples being dimethyltin diacetate, dibutyltin diacetate, dibutyitin dibutyrate, dibutyltin bis(2-ethylhexanoate), dibutyltin dilaurate, dibutyltin maleate, dioctyltin dilaurate and dioctyltin diacetate. Metal complexes such as acetyl acetonates of iron, of titanium, of aluminum, of zirconium, of manganese, of nickel and of cobalt are possible as well. Further useful metal compounds are described by Blank et al. in Progress in Organic Coatings, 1999, 35, 19 ff.
Preferred Lewis-acidic organic metal compounds are dimethyltin diacetate, dibutyltin dibutyrate, dibutyltin bis(2-ethylhexanoate), dibutyltin dilaurate, dioctyltin dilaurate, zirconium acetylacetonate and zirconium 2,2,6,6-tetramethyl-3,5-heptanedionate.
Similarly, bismuth and cobalt catalysts and also cesium salts can be used as hydrophilic catalysts. Useful cesium salts include cesium compounds utilizing the following anions: F−, Cl−, ClO−, ClO3−, ClO4−, Br−, I−, IO3−, CN−, OCN−, NO2−, NO3−, HCO3−, CO32−, S2−, SH−, HSO3−, SO32 −, HSO4−, SO42−, S2O22−, S2O42−, S2O52−, S2O62 −, S2O72−, S2O82−,H 2PO2−, H2PO4−, HPO42−, PO43−, P2O74−, (OCnH2n+)−, (CnH2n−1O2)−, (CnH2n−3O2)− and (Cn+1O2)2−, where n represents integers from 1 to 20.
Preference is given to cesium carboxylates in which the anion conforms to the formulae (CnH2n−1O2)− and also (Cn+1H2n−2O4)2− where n is from 1 to 20. Particularly preferred cesium salts comprise monocarboxylates of the general formula (CnH2−1O2)-, where n represents integers from 1 to 20, as anions. Formate, acetate, propionate, hexanoate and 2-ethylhexanoate must be mentioned in particular here.
As customary organic amines there may be mentioned by way of example: triethylamine, 1,4-diazabicyclo[2,2,2]octane, tributylamine, dimethylbenzylamine, N,N,N′,N′-tetramethylethylenediamine, N,N,N′,N′-tetramethylbutane-1,4-diamine, N,N N′,N′-tetramethylhexane-1,6-diamine, dimethylcyclohexylamine, dimethyl-dodecylamine, pentamethyldipropylenetriamine, pentamethyldiethylenetriamine, 3-methyl-6-dimethylamino-3-azapentol, dimethylaminopropylamine, 1,3-bisdimethyl-aminobutane, bis(2-dimethylaminoethyl) ether, N-ethylmorpholine, N-methyl-morpholine, N-cyclohexylmorphoiine, 2-dimethylaminoethoxyethanol, dimethylethanol-amine, tetramethylhexamethylenediamine, dimethylamino-N-methylethanolamine, N-methyiimidazole, N-formyl-N,N′-dimethylbutylenediamine, N-dimethylaminoethyl-morpholine, 3,3′-bisdimethylamino-di-n-propylamine and/or 2,2′-dipiparazine diisopropyl ether, dimethylpiparazine, tris(N,N-dimethylaminopropyl)-s-hexahydro-triazine, imidazoles such as 1,2-dimethylimidazole, 4-chloro-2,5-dimethyl-1-(N-methyl-aminoethyl) imidazole, 2-aminopropyl-4,5-dimethoxy-1-methylimidazole, 1-aminopropyl-2,4,5-tributylimidazole, 1-aminoethyl-4-hexylimidazoie, 1-aminobutyl-2,5-dimethyl-imidazole, 1-(3-aminopropyl)-2-ethyl-4-methylimidazole, 1-(3-aminopropyl)imidazole and/or 1-(3-aminopropyl)-2-methylimidazole.
Preferred organic amines are trialkylamines having independently two C1- to C4-alkyl radicals and one alkyl or cycloalkyl radical having 4 to 20 carbon atoms, for example dimethyl-C4-C15-alkylamine such as dimethyidodecylamine or dimethyl-C3-C8-cycloalkylamine. Likewise preferred organic amines are bicyclic amines which may if appropriate comprise a further heteroatom such as oxygen or nitrogen such as for example 1,4-diazabicyclo[2,2,2]octane.
It is particularly preferable to use ammonium acetate or triethylamine and most preferable to use N,N,N-trimethyl-N-(2-hydroxypropyl)ammonium 2-ethylhexanoate.
It will be appreciated that mixtures of two or more of the aforementioned compounds may be used as catalysts as well.
Particular preference is given to using such catalysts selected from the aforementioned compounds as are soluble in organic solvents such as acetone, tetrahydrofuran (THF), N-methylpyrrolidone and/or N-ethylpyrrolidone.
Catalyst is preferably used in an amount from 0.0001% to 10% by weight and more preferably in an amount from 0.001% to 5% by weight, based on diisocyanate (a1).
The catalyst or catalysts may be added in solid or liquid form or in solution, depending on the constitution of the catalyst or catalysts. Useful solvents include water-immiscible solvents such as aromatic or aliphatic hydrocarbons such as for example toluene, ethyl acetate, hexane and cyclohexane and also carboxylic esters such as for example ethyl acetate, useful solvents further including acetone, THF and N-methylpyrrolidone and N-ethylpyrrolidone. The catalyst or catalysts is or are preferably added in solid or liquid form and most preferably in solution in organic solvents such as acetone, tetrahydrofuran (THF), N-methylpyrrolidone or N-ethylpyrrolidone.
Diisocyanate (a1) is selected for example from aliphatic, aromatic and cycloaliphatic diisocyanates. Examples of aromatic diisocyanates are 2,4-tolylene diisocyanate (2,4-TDI), 2,4′-diphenylmethane diisocyanate (2,4′-MDI) and so-called TDI mixtures (mixtures of 2,4-tolylene diisocyanate and 2,6-tolyiene diisocyanate).
Examples of aliphatic diisocyanates are 1,4-butylene diisocyanate, 1,12-dodeca-methylene diisocyanate, 1,10-decamethylene diisocyanate, 2-butyl-2-ethylpenta-methylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate or 2,2,4-trimethylhexamethylene diisocyanate and in particular hexamethylene diisocyanate (HDI).
Examples of cycloaliphatic diisocyanates are isophorone diisocyanate (IPDI), 2-isocyanatopropylcyclohexyl isocyanate, 2,4′-methylenebis(cyclohexyl) diisocyanate and 4-methylcyclohexane 1,3-diisocyanate (H-TDI).
Further examples of isocyanates having groups of differing reactivity are 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 1,5-naphthylene diisocyanate, diphenyl diisocyanate, tolidine diisocyanate and 2,6-tolylene diisocyanate.
Mixtures of the aforementioned diisocyanates can be used, of course.
Diisocyanate (a1) and compound (a2) can be employed in molar ratios of for example from 10:1 to 1:1 and preferably from 5:1 to 5:4.
In one embodiment of the present invention, diisocyanate (a1) and compound (a2) can be reacted with each other at temperatures in the range from 20° C. to 150° C. and preferably from 50 to 130° C.
In one embodiment of the present invention, diisocyanate (a1) and compound (a2) can be reacted in solvents, preferably in an organic solvent or a mixture of organic solvents such as for example toluene, acetone or tetrahydrofuran or mixtures thereof. In another embodiment of the present invention, the reaction of diisocyanate (a1) with compound (a2) is carried out without use of solvent.
In one embodiment of the present invention, the reaction conditions for the reaction of diisocyanate (a1) with compound (a2), for example the molar ratios of diisocyanate (a1) and compound (a2), are chosen such that diisocyanate (a) has 2 isocyanate groups and from 1 to 10 allophanate groups and from 1 to 10 C—C double bonds but no O—CO—NH groups. In another embodiment of the present invention, the reaction conditions for the reaction of diisocyanate (a1) with compound (a2), for example the molar ratios of diisocyanate (a1) and compound (a2), are chosen such that diisocyanate (a) has 2 isocyanate groups and from 1 to 9 allophanate groups and from 1 to 9 C—C double bonds and also one or more O—CO—NH groups.
After the reaction of diisocyanate (a1) with compound (a2) has ended, di- or polyisocyanate (a) can be isolated, for example by removing unconverted starting materials such as diisocyanate (a1) or compound (a2). A suitable method of removing unconverted starting materials such as diisocyanate (a1) and compound (a2) is to distill them out, preferably at reduced pressure. Thin film evaporators are very particularly suitable. Unconverted diisocyanate (a1) is preferably not removed by distillation.
In one embodiment of the present invention, di- or polyisocyanate (a) has a dynamic viscosity at 23° in the range from 500 to 2000 mPa·s, preferably in the range from 600 to 1800 mPa·s and most preferably in the range from 700 to 1500 mPa·s.
In one embodiment of the present invention, di- or polyisocyanate (a) has an NCO content in the range from 8% to 20% by weight and preferably in the range from 12% to 17% by weight, determinable by titration for example.
Radiation-curable polyurethane (A) is prepared by reacting di- or polyisocyanate (a) with at least one further diisocyanate (b). Diisocyanate (b) can be selected from the abovementioned aliphatic, aromatic and cycloaliphatic diisocyanates. Diisocyanate (b) is other than diisocyanate (a) and therefore is referred to as “further diisocyanate” in the realm of the present invention,
In one embodiment of the present invention, diisocyanate (b) is chosen so that it is other than diisocyanate (a1).
In one embodiment of the present invention, diisocyanate (b) is chosen so that it is like diisocyanate (a1). One specific embodiment of the present invention comprises selecting diisocyanate (b) to be like diisocyanate (a1) by not separating from unconsumed diisocyanate (a1) after the preparation of diisocyanate (a) has ended.
Radiation-curable polyurethane (A) is further prepared by reacting with at least one compound having at least two isocyanate-reactive groups (c) which is also referred to as compound (c) in the realm of the present invention. Particularly readily isocyanate-reactive groups include for example the SH group, the hydroxyl group, the NH2 group and the NHR3 group, in which R3 is as defined above.
Compound (c) may be hydrophilic or hydrophobic.
At least one compound (c) is preferably selected from 1,1,1-trimethylol-C1-C4-alkyl-carboxylic acids, for example 1,1,1-trimethylol acetic acid, 1,1,1-trimethylolpropanoic acid, 1,1,1-trimethylolbutyric acid, citric acid, 1,1-dimethylol-C1-C4-alkylcarboxylic acids, for example 1,1-dimethylolacetic acid, 1,1-dimethylolpropanoic acid, 1,1-dimethylolbutyric acid, 1,1 -dimethylol-C1-C4-alkylsulfonic acids, poly-C2-C3-alkylene glycols having on average from 3 to 300 alkylene oxide units per molecule, in particular polyethylene glycol having on average (number average) from 3 to 300 ethylene oxide units per molecule and polyaddition products of ethylene oxide and propylene oxide having on average (number average) from 3 to 300 ethylene oxide units per molecule and a molar fraction of ethylene oxide higher than the fraction of propylene oxide;
hydrophilic diamines having COOM or SO3M groups, for example
where M is selected from alkali metal ions, in particular Na+, and ammonium ions, polyesterdiols preparable by polycondensation of
at least one aliphatic or cycloaliphatic diol, preferably ethylene glycol, 1,4-butanediol, 1,6-hexanediol, cis-1,4-cyclohexanediol, trans-1,4-cyclohexanediol, cis- and trans-1,4-dihydroxymethylcyclohexane (cyclohexanedimethanol), with at least one aliphatic, aromatic or cycloaliphatic dicarboxylic acid, examples being succinic acid, glutaric acid, adipic acid, cyclohexane-1,4-dicarboxylic acid, terephthalic acid, isophthalic acid.
One embodiment of the present invention comprises selecting at least two dicarboxylic acids for preparing polyesterdiol of which one is aromatic and the other is aliphatic, examples being succinic acid and isophthalic acid, glutaric acid and isophthalic acid, adipic acid and isophthalic acid, succinic acid and terephthalic acid, glutaric acid and terephthalic acid, adipic acid and terephthalic acid.
To prepare polyesterdiol using two or more dicarboxylic acids, any desired molar ratios can be used. When an aromatic dicarboxylic acid and an aliphatic dicarboxylic acid are to be used, a molar ratio in the range from 10:1 to 1:10 is preferred, a molar ratio in the range from 1.5:1 to 1:1.5 is peculiar.
In one embodiment of the present invention, polyesterdiols used as compound (c) have a hydroxyl number in the range from 20 to 200 mg KOH/g, preferably in the range from 50 to 180 and most preferably in the range from 100 to 160 mg KOH/g, determined according to German standard specification DIN 53240.
In one embodiment of the present invention, polyesterdiols used as compound (c) have a molecular weight Mw in the range from 500 to 100 000 g/mol, preferably in the range from 700 to 50 000 g/mol and more preferably up to 30 000 g/mol.
Further suitable compounds (b) are ethanolamine, diethanolamine, neopentylglycol, 1,4-butanediol, 1,6-hexanediol, 1,1-dimethylolpropane.
One embodiment of the present invention comprises reacting with at least two compounds (c) of which one is selected from ethanolamine, diethanolamine, neopentylglycol, 1,4-butanediol, 1,6-hexanediol, 1,1-dimethylolpropane.
One embodiment of the present invention comprises synthesizing radiation-curable polyurethane (A) by
Compounds of the formula I are described above.
As compound (d) of the general formula I there may be used a compound of the general formula I other than for preparing di- or polyisocyanate (a) which on average comprises from 1 to 10 allophanate groups and on average from 1 to 10 C—C double bonds per molecule. Preferably, however, compound (d) and compound (a2) are identical.
The synthesis of radiation-curable polyurethane (a) can be carried out by conventional methods of polyurethane chemistry.
One embodiment of the present invention utilizes di- or polyisocyanate (a), further diisocyanate (b) and compound (c) and if appropriate further compound of the general formula I (d) in the following weight ratios, each based on entire radiation-curable polyurethane (A):
from 0.1% to 10% by weight and preferably from 1% to 6% by weight of di- or polyisocyanate (a),
from 20% to 60% by weight and preferably from 30% to 55% by weight of further diisocyanate (b),
from 3% to 20% by weight and preferably from 5% to 15% by weight of compound (c), from 0% to 20% by weight and preferably from 5% to 15% by weight of compound of the general formula I (d).
Each weight % age is based on entire radiation-curable polyurethane (A) to be synthesized.
One preferred version of the present invention comprises preparing radiation-curable polyisocyanate (A) by reacting not only di- or polyisocyanate (a), further diisocyanate (b) and compound (c) and if appropriate further compound of the general formula I (d) but additionally with at least one nucleophilic alcohol or amine, preferably monoalcohol or monoamine, which in either case may serve as a stopper and hereinafter is designated stopper (e). Examples of suitable stoppers (e) are mono- and di-C1-C4-alkylamines, in particular diethylamine. Up to 10% by weight of stopper (e) can be used, based on radiation-curable polyurethane (A) to be synthesized.
The preparation of radiation-curable polyurethane (A) from di- or polyisocyanate (a), further diisocyanate (b), compound (c) and if appropriate further compound of the general formula I (d) and if appropriate stopper (e) can be carried out in one or more stages. For example, di- or polyisocyanate (a), further diisocyanate (b) and compound (c) can be reacted in a first stage, preferably in the presence of a catalyst, the reaction stopped and thereafter again diisocyanate (b) and compound of the general formula I (d) and if appropriate stopper (e) added. It is also possible for example to react di- or polyisocyanate (a), further diisocyanate (b) and compound (c) with one another using an excess of further diisocyanate (b), and to stop the reaction by adding stopper (e).
In one embodiment of the present invention, di- or polyisocyanate (a), further diisocyanate (b), compound (c) and if appropriate further compound of the general formula I (d) and if appropriate stopper (e) in a solvent, preferably in an organic solvent or a mixture of organic solvents such as for example toluene, acetone or tetrahydrofuran or mixtures thereof. In another embodiment of the present invention the reaction of di- or polyisocyanate (a), further diisocyanate (b), compound (c) and if appropriate further compound of the general formula I (d) and if appropriate stopper (e) is carried out without use of solvent.
One embodiment of the present invention comprises reacting di- or polyisocyanate (a), further diisocyanate (b) and compound (c) and if appropriate further compound of the general formula I (d) and if appropriate stopper (e) at temperatures in the range from 20° C. to 150° C. and preferably in the range from 20 to 80° C.
To speed the reaction of di- or polyisocyanate (a), further diisocyanate (b), compound (c) and if appropriate further compound of the general formula I (d) and if appropriate stopper (e), one or more catalysts can be used which is or are advantageously chosen from the aforementioned catalysts.
After the reaction of di- or polyisocyanate (a), further diisocyanate (b), compound (c) and if appropriate further compound of the general formula I (d) and if appropriate stopper (e) has ended, radiation-curable polyurethane (A) can be isolated, for example by removing unconverted starting materials such as diisocyanate (b), compound (c) and if appropriate further compound of the general formula I (d) and if appropriate stopper (e). A suitable method of removing unconverted starting materials such as (b) and (c) and if appropriate (d) and (e) is to distill them out, preferably at reduced pressure. Thin film evaporators are very particularly suitable. Preferably, unconverted diisocyanate (b) is not distilled out.
The molecular weight Mw of the radiation-curable polyurethanes (A) to be used for the present invention can be for example in the range from 500 to not more than 50 000 g/mol, preferably in the range from 1000 to 30 000 g/mol, more preferably in the range from 2000 to 25 000 g/mol and most preferably at least 2000 g/mol, determined by gel permeation chromatography (GPC) for example.
In a preferred embodiment of the present invention, radiation-curable polyurethane (A) comprises no free NCO groups.
After the reaction of di- or polyisocyanate (a), further diisocyanate (b) and compound (c) and if appropriate (d) and if appropriate stopper (e) has taken place, water can be added, for example in a weight ratio of radiation-curable polyurethane (A) to water in the range from 1:1 to 1:10.
After the reaction of di- or polyisocyanate (a), further diisocyanate (b) and compound (c) and if appropriate (d) and stopper (e) has taken place, groups comprising sufficiently acidic hydrogen atoms can be treated with bases to convert them into the corresponding salts. Useful bases include for example hydroxides and bicarbonates of alkali metals or alkaline earth metals or the carbonates of alkali metals. Useful bases further include volatile amines, i.e., amines having a boiling point of up to 180° C. at atmospheric pressure, examples being ammonia, methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, ethanolamine or N-methyl-diethanolamine. Similarly, basic groups can be converted with acids such as for example α-hydroxy carboxylic acids or α-amino acids or else α-hydroxy sulfonic acids into the corresponding salts.
After the reaction of di- or polyisocyanate (a), further diisocyanate (b) and compound (c) if appropriate (d) and stopper (e) has taken place, any organic solvent used can be separated off, for example by distillation.
After radiation-curable polyurethane (A) has been prepared, one or more pigments (B) and if appropriate water are added, It is preferable to set a solids content in the range from to 3% to 40%, preferably to 35% and more preferably in the range from 5% to 30%.
The weight ratio of radiation-curable polyurethane (A) to pigment (B) can vary within wide limits. In one embodiment of the present invention, the weight ratio of radiation-curable polyurethane (A) to pigment (B) is in a range from 5:1 to 1:3, preferably from 3:1 to 1:2 and more preferably from 2:1 to 2:3.
Radiation-curable polyurethane (A) and pigment (B) are subsequently dispersed. The dispersing can be effected in any apparatus suitable for dispersing. Shaking apparatuses as for example from Skandex may be mentioned by way of example. Preferably, radiation-curable polyurethane (A) and pigment (B) are dispersed for example in ultrasonic apparatuses, high pressure homogenizers, 2-, 3-, 4- or 5-roll mills, minimills, Henschel mixers, shaking mills, Ang mills, gear mills, bead mills, wet mills, sand mills, attritors, colloid mills, ultrasonic homogenizers, with Ultra Turrax stirrer and in particular by grinding, for example in 2-, 3-, 4- or 5-roll mills, minimills, shaking mills, Ang mills, gear mills, bead mills, wet mills, sand mills, colloid mills, ball mills, specifically stirred ball mills.
The dispersing time is suitably in the range from 10 minutes to 48 hours for example, although a longer time is conceivable as well. Preference is given to a dispersing time in the range from 15 minutes to 24 hours.
Pressure and temperature conditions during the dispersing are generally not critical in that for example atmospheric pressure has been found to be suitable. As temperatures, for example temperatures in the range from 10° C. to 100° C. have been found to be suitable, preferably up to 80° C.
The dispersing provides aqueous dispersion according to the present invention. In one embodiment of the present invention, aqueous dispersions according to the present invention have a solids content in the range from 3% to 40%, preferably up to 35% and more preferably in the range from 5% to 30%.
Customary grinding aids can be added during the dispersing.
The average diameter of pigment (B) at least partially enveloped by radiation-curable polyurethane (A) is typically in the range from 20 nm to 1.5 μm, preferably in the range from 60 to 500 nm and more preferably in the range from 60 to 350 nm after the dispersing and in connection with the present invention generally signifies the volume average. Useful measuring appliances for determining the average particle diameter include for example Coulter Counters, for example Coulter LS 230.
When it is desired to use carbon black according to the present invention as pigment (B), the particle diameter is based on the average diameter of the primary particles.
Aqueous dispersions according to the present invention comprise no thermal initiator, i.e., no compound which has a half-life of at least one hour at 60° C. and splits into free radicals in the process, examples being peroxides, hydroperoxides, hydrogen peroxide, persulfates, azo compounds such as for example azobisisobutyronitrile (AIBN) or water-soluble AIBN derivatives, highly substituted, in particular hexasubstituted, ethane derivatives or redox catalysts.
In one embodiment of the present invention, aqueous dispersions according to the present invention comprise at least one polyurethane (C). Polyurethane (C) is obtainable for example by reaction of diisocyanate (b) with compound (c), preferably comprises no allophanate groups. Particularly preferably pigment (B) is at least partially enveloped not just by radiation-curable polyurethane (A) but also by polyurethane (C).
In one embodiment of the present invention, aqueous dispersions according to the present invention comprise radiation-curable polyurethane (A) and polyurethane (C) in the range from 10:1 to 1:2 and preferably in the range from 8:1 to 1:1 (weight ratio).
In one embodiment of the present invention, aqueous dispersions according to the present invention comprise at least one photoinitiator (D). Photoinitiator (D) can be added either before the dispersing or alternatively after the dispersing.
Suitable photoinitiators (D) include for example photoinitiators known to one skilled in the art, examples being those mentioned in “Advances in Polymer Science”, Volume 14, Springer Berlin 1974 or in K. K. Dietliker, Chemistry and Technology of UV- and EB-Formulation for Coatings, Inks and Paints, Volume 3; Photoinitiators for Free Radical and Cationic Polymerization, P. K. T. Oldring (Eds), SITA Technology Ltd, London.
Useful photoinitiators include for example mono- or bisacylphosphine oxides as described for example in EP-A 0 007 508, EP-A 0 057 474, DE-A 196 18 720, EP-A 0 495 751 and EP-A 0 615 980, examples being 2,4,6-trimethylbenzoyldiphenylphosphine oxide, ethyl 2,4,6-trimethylbenzoylphenylphosphinate, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, benzophenone, hydroxyacetophenone, phenylglyoxylic acid and derivatives thereof or mixtures of the aforementioned photoinitiators. As examples there may be mentioned benzophenone, acetophenone, acetonaphthoquinone, methyl ethyl ketone, valerophenone, hexanophenone, α-phenylbutyrophenone, p-morpholinopropio-phenone, dibenzosuberone, 4-morpholinobenzophenone, 4-morpholinodeoxybenzoin, p-diacetylbenzene, 4-aminobenzophenone, 4′-methoxyacetophenone, β-methylanthra-quinone, tert-butylanthraquinone, anthraquinonecarboxylic esters, benzaidehyde, α-tetraione, 9-acetylphenanthrene, 2-acetylphenanthrene, 10-thioxanthenone, 3-acetylphenanthrene, 3-acetylindole, 9-fluorenone, 1-indanone, 1,3,4-triacetyl-benzene, thioxanthen-9-one, xanthen-9-one, 2,4-dimethylthioxanthone, 2,4-diethylthio-xanthone, 2,4-di-iso-propylthioxanthone, 2,4dichlorothioxanthone, benzoin, benzoin isobutyl ether, chloroxanthenone, benzoin tetrahydropyranyl ether, benzoin methyl ether, benzoin ethyl ether, benzoin butyl ether, benzoin isopropyl ether, 7-H-benzoin methyl ether, benz[de]anthracen-7-one, 1-naphthaldehyde, 4,4′-bis(dimethylamino)-benzophenone, 4-phenylbenzophenone, 4-chlorobenzophenone, Michler's ketone, 1-acetonaphthone, 2-acetonaphthone, 1-benzoyicyclohexan-1-ol, 2-hydroxy-2,2-di-methylacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenyl-acetophenone, 1,1-dichloroacetophenone, 1-hydroxyacetophenone, acetophenone dimethyl ketal, o-methoxybenzophenone, triphenylphosphine, tri-o-tolylphosphine, benz[a]anthracene-7,12-dione, 2,2-diethoxyacetophenone, benzil ketals, such as benzil dimethyl ketal, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, anthraquinones such as 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone, 2-amylanthraquinone and 2,3-butanedione.
Also suitable are nonyellowing or minimally yellowing photoinitiators of the phenylglyoxalic ester type, as described in DE-A 198 26 712, DE-A 199 13 353 or WO 98/33761.
Preferred photoinitiators (D) include for example photoinitiators which split upon activation, so-called α-splitters such as for example photoinitiators of the benzil dialkyl ketal type such as for example benzil dimethyl ketal. Further examples of useful α-splitters are derivatives of benzoin, isobutyl benzoin ether, phosphine oxides, especially mono- and bisacylphosphine oxides, for example benzoyidiphenylphosphine oxide, 2,4,6-trinethylbenzoyidiphenylphosphine oxide, α-hydroxyalkylacetophenones such as for example 2-hydroxy-2-methylphenylpropanone (D.1),
2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone (D.2)
phosphine sulfides and ethyl 4-dimethylaminobenzoate and also (D.3)
Preferred photoinitiators (D) further include for example hydrogen-abstracting photoinitiators, for example of the type of the substituted or unsubstituted acetophenones, anthraquinones, thioxanthones, benzoic esters or of the substituted or unsubstituted benzophenones. Particularly preferred examples are isopropylthio-xanthone, benzophenone, phenyl benzyl ketone, 4-methylbenzophenone, halomethylated benzophenones, anthrone, Michler's ketone (4,4′-bis-N,N-dimethyl-aminobenzophenone), 4-chlorobenzophenone, 4,4′-dichlorobenzophenone, anthraquinone.
In one embodiment of the present invention, sufficient photoinitiator (D) is added to aqueous dispersions according to the present invention that the weight ratio of radiation-curable polyurethane (A) to photoinitiator (D) is in a range from 3:1 to 10 000:1, preferably fro m 5:1 to 5000:1 and most preferably in a weight ratio from 10:1 to 1000:1.
The efficacy of photoinitiators (D) in aqueous dispersions (A) according to the present invention can if desired be enhanced by the addition of at least one synergist, for example of at least one amine, especially of at least one tertiary amine. Useful amines include for example triethylamine, N,N-dimethylethanolamine, N-methylethanolamine, triethanolamine, amino acrylates such as for example amine-modified polyether acrylates. When amines such as for example tertiary amines have been used as a catalyst in the synthesis of radiation-curable polyurethane (a) and have not been removed after synthesis, it is also possible for tertiary amine used as a catalyst to act as a synergist. Similarly, tertiary amine used to neutralize acidic groups such as for example COOH groups or SO3H groups can act as a synergist. Up to twice the molar amount of synergist can be added, based on photoinitiator (A) used.
Aqueous dispersions according to the present invention may be additized with at least one polymerization inhibitor (E) such as UV absorbers or free-radical scavengers. UV absorbers convert UV radiation into thermal energy. Useful UV absorbers include for example oxanilides, triazines and benzotriazole (the latter are obtainable as Tinuvin® brands from Ciba-Spezialitatenchemie), benzophenones, hydroxybenzophenones, hydroquinone, hydroquinone monoalkyl ethers such as for example hydroquinone monomethyl ether. Free-radical scavengers bind free-radical intermediates. Useful free-radical scavengers include for example sterically hindered amines which are known as HALS (hindered amine light stabilizers). Examples thereof are 2,2,6,6-tetra-methylpiperidine, 2,6-di-tert-butylpiperidine or derivatives thereof, an example being bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate.
For example, up to 5% by weight, based on the sum total of (A) and (B), of polymerization inhibitor (E) may be added, more preferably up to 0.5% by weight.
Dispersions according to the present invention may be additized with one or more further compounds having C—C double bonds (F), hereinafter also referred to as unsaturated compounds (F). Particularly suitable unsaturated compounds (F) include for example compounds of the general formula 1. Further particularly suitable unsaturated compounds (F) are those of the general formula F. 1
where
Particularly preferred examples of compounds of the general formula F.I are trimethylolpropane tri(meth)acrylate, tri(meth)acrylate of triply ethoxylated trimethylolpropane, pentaerythritol tri(meth)acrylate and pentaerythritol tetra(meth)acrylate.
Further very useful representatives of unsaturated compounds (F) are ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, propylene glycol (meth)acrylate, dipropylene glycol di(meth)acrylate and tripropylene glycol di(meth)acrylate.
Further very useful representatives of unsaturated compounds (F) are partially or exhaustively (meth)acrylated polyols such as for example partially or exhaustively (meth)acrylated dimeric trimethylolpropane, partially or exhaustively (meth)acrylated dimeric trimethylolethane, partially or exhaustively (meth)acrylated dimeric pentaerythritol.
For example, a total of up to 100% by weight, based on the sum total of (A) and (B), of unsaturated compound (F) can be added, preferably up to 50% by weight and more preferably up to 25% by weight.
Aqueous dispersions according to the present invention are very useful as or for producing formulations for dyeing or printing substrates, for example for producing dyeing liquors for pigment dyeing or for producing print pastes for pigment printing. The present invention therefore further provides for the use of aqueous dispersions according to the present invention as or for producing formulations for dyeing or printing substrates. The present invention similarly provides a process for dyeing or printing substrates by using at least one aqueous dispersion according to the present invention.
cellulosic materials such as paper, board, card, wood and woodbase, which may each be lacquered or otherwise coated,
metallic materials such as foils, sheets or workpieces composed of aluminum, iron, copper, silver, gold, zinc or alloys thereof, which may each be lacquered or otherwise coated,
silicatic materials such as glass, porcelain and ceramic, which may each be coated, polymeric materials of any kind such as polystyrene, polyamides, polyesters, polyethylene, polypropylene, melamine resins, polyacrylates, polyacrylonitrile, polyurethanes, polycarbonates, polyvinyl chloride, polyvinyl alcohols, polyvinyl acetates, polyvinylpyrrolidones and corresponding copolymers including block copolymers, biodegradable polymers and natural polymers such as gelatin, leather—both natural and artificial—in the form of smooth leather, nappa leather or suede leather, comestibles and cosmetics, and in particular
textile substrates such as fibers, yarns, threads, knits, wovens, nonwovens and garments composed of polyester, modified polyester, polyester blend fabric, cellulosic materials such as cotton, cotton blend fabric, jute, flax, hemp and ramie, viscose, wool, silk, polyamide, polyamide blend fabric, polyacrylonitrile, triacetate, acetate, polycarbonate, polypropylene, polyvinyl chloride, blend fabric such as for example polyester-polyurethane blend fabric (e.g. Lycra(®), polyethylene-polypropylene blend fabric, polyester microfibers and glass fiber fabric.
Aqueous dispersions according to the present invention are particularly useful as or for producing inks for the ink jet process, in particular aqueous inks for the ink jet process. Aqueous dispersions according to the present invention are very particularly useful for producing pigment-containing aqueous inks for the ink jet process. The present invention thus further provides for the use of aqueous dispersions according to the present invention for producing inks for the ink jet process. The present invention further provides a process for producing inks for the ink jet process, which comprises utilizing at least one aqueous dispersion according to the present invention.
In the realm of the present invention, inks for the ink jet process will also be referred to as ink jet inks or in short as inks.
In one embodiment of the present invention, ink jet inks according to the present invention comprise from 1% to 40% by weight and preferably from 2% to 35% by weight of aqueous dispersion according to the present invention, the weight % ages each being based on the total weight of the relevant ink according to the present invention.
Aqueous dispersions according to the present invention can also be used directly as ink jet inks.
Ink jet inks according to the present invention may comprise at least one extra (G) in another embodiment.
In one embodiment of the present invention, ink jet inks according to the present invention are produced by thinning aqueous dispersion according to the present invention with water and if appropriate mixing it with one or more extras (G).
In one embodiment of the present invention, ink jet inks according to the present invention are set to a solids content in the range from 5% to 40%, preferably up to 35% and more preferably in the range from 10% to 30%.
Ink jet process inks according to the present invention may comprise one or more organic solvents as extra (G). Low molecular weight polytetrahydrofuran (poly-THF) is a preferred extra (G), it can be used alone or preferably in admixture with one or more high-boiling, water-soluble or water-miscible organic solvents.
The average molecular weight Mw of preferred low molecular weight polytetrahydro-furan is typically in the range from 150 to 500 g/mol, preferably in the range from 200 to 300 g/mol and more preferably about 250 g/mol (in keeping with a molecular weight distribution).
Polytetrahydrofuran is preparable in a known manner by cationic polymerization of tetrahydrofuran. The products are linear polytetramethylene glycols.
When polytetrahydrofuran is used as an extra (G) in admixture with further organic solvents, the further organic solvents employed will generally be high-boiling (i.e., boiling point >100° C. at atmospheric pressure, in general) and hence water-retaining organic solvents which are soluble in or miscible with water.
Useful solvents include polyhydric alcohols, preferably unbranched and branched polyhydric alcohols having from 2 to 8 and especially from 3 to 6 carbon atoms, such as ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, glycerol, erythritol, pentaerythritol, pentitols such as arabitol, adonitol and xylitol and hexitols such as sorbitol, mannitol and dulcitol.
Useful solvents further include polyethylene glycols and polypropylene glycols including their lower polymers (di-, tri- and tetramers) and their mono(especially C1-C6 and especially C1-C4)alkyl ethers. Preference is given to polyethylene and polypropylene glycols having average molecular weights Mn in the range from 100 to 6000 g/mol, especially to 1500 g/mol and in particular in the range from 150 to 500 g/mol. As examples there may be mentioned diethylene glycol, triethylene glycol and tetraethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monoisopropyl ether, diethylene glycol monopropyl ether, diethylene glycol mono-n-butyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol mono-n-propyl ether, triethylene glycol monoisopropyl ether, triethylene glycol mono-n-butyl ether, di-, tri- and tetra-1,2- and -1,3-propylene glycol and di-, tri- and tetra-1,2- and -1,3-propylene glycol monomethyl, monoethyl, mono-n-propyl, monoisopropyl and mono-n-butyl ethers.
Useful solvents further include pyrrolidone and N-alkylpyrrolidones whose alkyl chain preferably comprises from 1 to 4 and in particular 1 or 2 carbon atoms. Examples of useful alkylpyrrolidones are N-methylpyrrolidone, N-ethylpyrrolidone and N-(2-hydroxyethyl)pyrrolidone.
Examples of particularly preferred solvents are 1,2-propylene glycol, 1,3-propylene glycol, glycerol, sorbitol, diethylene glycol, polyethylene glycol (Mw b 300 to 500 g/mol), diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, pyrrolidone, N-methylpyrrolidone and N-(2-hydroxyethyl)pyrrolidone.
Polytetrahydrofuran can also be mixed with one or more (for example two, three or four) of the solvents recited above.
In one embodiment of the present invention, ink jet process inks according to the present invention may comprise from 0.1 % to 80% by weight, preferably from 2% to 60% by weight, more preferably from 5% to 50% by weight and most preferably from 10% to 40% by weight of nonaqueous solvents.
Nonaqueous solvents used as extras (G), including in particular the identified particularly preferred solvent combinations, may preferably be supplemented with urea (generally in the range from 0.5% to 3% by weight, based on the weight of the colorant preparation) to further enhance the water-retaining effect of the solvent mixture.
Ink jet process inks according to the present invention may comprise further extras (G) of the kind which are customary especially for aqueous ink jet inks and in the printing and coatings industries. Examples include preservatives such as for example 1,2-benzisothiazolin-3-one (commercially available as Proxel brands from Avecia Lim.) and its alkali metal salts, glutaraldehyde and/or tetramethylolacetylenediurea, Protectols®, antioxidants, degassers/defoamers such as for example acetylenediols and ethoxylated acetylenediols, which typically comprise from 20 to 40 mol of ethylene oxide per mole of acetylenediol and may also have a dispersing effect, viscosity regulators, flow agents, wetters (for example wetting surfactants based on ethoxylated or propoxylated fatty or oxo alcohols, propylene oxide-ethylene oxide block copolymers, ethoxylates of oleic acid or alkylphenols, alkylphenol ether sulfates, alkylpolyglycosides, alkyl phosphonates, alkylphenyl phosphonates, alkyl phosphates, alkylphenyl phosphates or preferably polyethersiloxane copolymers, especially alkoxylated 2-(3-hydroxypropyl)heptamethyltrisiloxanes, which generally comprise a block of 7 to 20 and preferably 7 to 12 ethylene oxide units and a block of 2 to 20 and preferably 2 to 10 propylene oxide units and may be comprised in the colorant preparations in amounts from 0.05% to 1% by weight), anti-settlers, luster improvers, glidants, adhesion improvers, anti-skinning agents, delusterants, emulsifiers, stabilizers, hydrophobicizers, light control additives, hand improvers, antistats, bases such as for example triethanolamine or acids, specifically carboxylic acids such as for example lactic acid or citric acid to regulate the pH. When these agents are a constituent part of ink jet process inks according to the present invention, their total amount will generally be 2% by weight and especially 1% by weight, based on the weight of the present invention's colorant preparations and especially of the present invention's inks for the ink jet process.
Useful extras (G) further include alkoxylated or nonalkoxylated acetylenediols, for example of the general formula II
where
In a preferred embodiment of the present invention, R5 or R7 are methyl.
In a preferred embodiment of the present invention, R5 and R7 are methyl and R4 and R6 are isobutyl.
Other preferred extras are alkoxylated or nonalkoxylated silicon compounds of the formula III
[(CH3)3Si—O]2—Si(CH3)—O(CH2CH2O)b—H III
where b is as defined above.
Ink jet process inks according to the present invention may further comprise a further photoinitiator other than the photoinitiator (D) which can be used in the preparation of aqueous dispersion according to the present invention, but is selected from the photoinitiators identified above.
Ink jet process inks according to the present invention in one embodiment of the present invention have a dynamic viscosity in the range from 2 to 80 mPa·s, preferably from 3 to 40 mPa·s, and more preferably up to 25 mPa·s, measured at 23° C. in accordance with German standard specification DIN 53018.
The surface tension of ink jet process inks according to the present invention in one embodiment of the present invention is in the range from 24 to 70 mN/m and especially in the range from 25 to 60 mN/m, measured at 25° C. in accordance with German standard specification DIN 53993.
The pH of ink jet process inks according to the present invention in one embodiment of the present invention is in the range from 5 to 10 and preferably in the range from 7 to 9.
Ink jet process inks according to the present invention have altogether advantageous performance characteristics, in particular good start-of-print performance and good sustained use performance (kogation) and also, especially when the particularly preferred solvent combination is used, good drying performance, and produce printed images of high quality, i.e., of high brilliance and depth of shade and also high dry rub, light, water and wet rub fastness. They are particularly useful for printing coated and plain paper and also textile substrates.
A further aspect of the present invention is a process for producing ink jet process inks according to the present invention. The present invention's process for producing inks for the ink jet process comprises mixing at least one aqueous dispersion according to the present invention, water and if appropriate at least one extra (G) with one another, for example in one or more steps.
Useful mixing techniques include for example stirring and intensive shaking and also dispersing, for example in ball mills or stirred ball mills.
The order of addition when mixing aqueous dispersion according to the present invention, water, if appropriate (C), if appropriate (D), if appropriate (E), if appropriate (F) and if appropriate (G) is as such not critical.
It is accordingly possible, in one version of the present invention, first for at least one radiation-curable polyurethane (A) to be synthesized, then dispersed with pigment (B) and thereafter mixed with one or more of the desired additives (C), (D), (E), (F) and/or (G) and, before or after the mixing, thinned with water.
In another version of the present invention, (a) at least one radiation-curable polyurethane (A) and at least one polyurethane (C) are synthesized, then dispersed with (B), thinned with water and mixed with one or more of the desired additives (D), (E), (F) and/or (G).
In another version of the present invention, at least one radiation-curable polyurethane (A) is synthesized and then dispersed with pigment (B) and at least one of the desired additives (C), (D), (E), (F) and (G).
In another version of the present invention, at least one radiation-curable polyurethane (A) and at least one polyurethane (C) are synthesized and then dispersed with pigment (B) and at least one of the desired additives (D), (E), (F) and (G).
A further aspect of the present invention is a process for printing sheetlike or three-dimensional substrates by the ink jet process using at least one ink jet process ink according to the present invention, hereinafter also referred to as inventive printing process. To practice the inventive printing process, at least one ink jet ink according to the present invention is printed onto a substrate. A preferred version of the inventive printing process comprises printing at least one ink jet ink of the present invention onto a substrate and then treating with actinic radiation.
In the ink jet process, the typically aqueous inks are sprayed as small droplets directly onto the substrate. There is a continuous form of the process, in which the ink is pressed at a uniform rate through a nozzle and the jet is directed onto the substrate by an electric field depending on the pattern to be printed, and there is an interrupted or drop-on-demand process, in which the ink is expelled only where a colored dot is to appear, the latter form of the process employing either a piezoelectric crystal or a heated hollow needle (Bubble or Thermal Jet process) to exert pressure on the ink system and so eject an ink droplet. These techniques are described in Text. Chem. Color, volume 19 (8), pages 23 to 29, 1987, and volume 21 (6), pages 27 to 32, 1989.
The inks of the present invention are particularly useful for the bubble jet process and for the process employing a piezoelectric crystal.
Ink jet inks according to the present invention are curable by actinic radiation. Actinic radiation having a wavelength range from 200 nm to 450 nm is useful for example. Actinic radiation having an energy in the range from 70 mJ/cm2 to 2000 mJ/cm2 is useful for example. Actinic radiation may advantageously be applied continuously or in the form of flashes for example.
In one embodiment of the present invention, the substrate materials after printing and before treatment with actinic radiation can be interdried, for example thermally or with IR radiation. Examples of suitable conditions are temperatures ranging from 30 to 120° C. for a period from 10 seconds to 24 hours, preferably up to 30 min, more preferably up to 5 min. Useful IR radiation includes for example IR radiation in a wave region above 800 nm. Useful interdrying apparatuses include for example drying cabinets including vacuum drying cabinets for thermal interdrying, and also IR lamps.
Similarly, the heat involved upon application of actinic radiation can have an interdrying effect.
The present invention further provides substrates, especially textile substrates, which have been printed by one of the inventive printing processes identified above and which are notable for particularly crisply printed images or drawings and also excellent hand. Moreover, printed substrates according to the present invention have few soft spots.
In a further embodiment of the present invention, two or more and preferably three or more different ink jet process inks according to the present invention can be combined into sets, in which case different inks according to the present invention each comprise different pigments each having a different color.
The present invention further provides at least partially enveloped pigments produced by dispersing at least one pigment (B) and at least one radiation-curable polyurethane (A), said radiation-curable polyurethane (A) being obtainable by reaction of
The present invention provides specifically at least partially enveloped above-described pigments wherein said di- or polyisocyanate (a) is prepared by reaction of at least one di- or polyisocyanate (a1) with at least one compound of the general formula I
where
The present invention provides specifically at least partially enveloped pigment wherein radiation-curable polyurethane (A) is prepared by reaction of
where
A process for producing at least partially enveloped pigments according to the present invention is described above and likewise forms part of the subject matter of the present invention.
At least partially enveloped pigments according to the present invention are winnable for example from aqueous dispersions according to the present invention by removing the water, for example by drying, freeze drying, filtration or a combination thereof.
At least partially enveloped pigments according to the present invention are particularly useful for producing inks for the ink jet process.
The present invention further provides radiation-curable polyurethanes prepared by reaction of
In one embodiment of the present invention, radiation-curable polyurethane (A) of the present invention has a double bond density in the range from 0.1 to 5 mol/kg of (A), preferably in the range from 0.2 to 3 mol/kg of (A) and most preferably in the range from 0.3 to 2 mol/kg of (A), determinable for example by determination of the hydrogenation iodine number and by 1H NMR spectroscopy.
A process for producing radiation-curable polyurethanes according to the present invention is described above and likewise forms part of the subject matter of the present invention.
Radiation-curable polyurethanes according to the present invention are particularly useful for producing ink jet inks according to the present invention and for producing aqueous dispersions according to the present invention.
The invention is illustrated by working examples.
The NCO content was in each case determined titrimetrically in accordance with German standard specification DIN 53185.
The degree of envelopment of pigments according to the present invention was determined by transmission electron microscopy using the freeze fracture technique. Tetrahydrofuran (THF) was dried over sodium/benzophenone by distillation before use. Solids content: % ages in the realm of the present invention are all % by weight. Solids contents in the realm of the present invention are all determined by drying at 150° C. for 30 minutes.
I.1.1 Preparation of Diisocyanate (a.1), which Comprises Allophanate Groups and C—C Double Bonds
Inventive aqueous dispersions were produced on a Skandex shaking apparatus using 60 g of glass balls 0.25-0.5 mm in diameter. The recipes are summarized in table 1. After the ingredients and the glass balls had been weighed into the Skandex, the resulting mixture was shaken for a time reported in table 1. Thereafter, a sample was taken and the average diameter of dispersed pigment determined (Coulter Counter LS230) and also the degree of envelopment measured. The pH was measured and—if necessary—adjusted to 7.5 with triethanolamine. Inventive aqueous dispersions WD.2.1 to WD.2.3 were obtained.
Amounts of ingredients always reported in g unless expressly stated otherwise.
Further inventive aqueous dispersions were obtained by proceeding as described above but in each case replacing (A.2) by (A.1) and (A.3) respectively. The following inventive aqueous dispersions were obtained:
WD.1.1 (magenta, using (A.1)),
WD.1.2 (black, using (A.1)),
WD.1.3 (yellow, using (1.2)),
WD.3.1 (magenta, using (A.3)),
WD.3.2 (black, using (A.3)),
WD.3.3 (yellow, using (A.3)),
The following were mixed with one another by stirring in a glass beaker:
The inventive ink T2.1.1 was obtained after filtering through a glass fiber filter (cutoff size 1 μm). The inventive ink T2.1.1 had a pH of 7.5 and a dynamic viscosity of 4.2 mPa·s.
The following were mixed with one another by stirring in a glass beaker:
The inventive ink T2.1.2 was obtained after filtering through a glass fiber filter (cutoff size 1 μm). The inventive ink T2.1.2 had a pH of 7.5 and a dynamic viscosity of 4.2 mPa·s.
III. Printing Trials with Inventive Inks for Ink Jet Process
The inventive inks T2.1.1 and T2.1.2 were each filled into a cartridge and printed onto paper using a Mimaki TX2 720 dpi. Five A4 pages were obtained without nozzle cloggage. The rub fastness tests produced good values.
Furthermore, the inventive inks T2.1.1 and T2.1.2 were each printed onto cotton using a Mimaki TX 2 720 dpi printer.
This was followed by fixing according to three variants: variant 1 was thermal drying with subsequent exposure to light, variant 2 was exposure to actinic radiation with subsequent thermal drying, and variant 3 was exposure to actinic radiation without thermal drying.
Thermal drying involved drying in a drying cabinet at 100° C. for 5 minutes.
Irradiation with actinic radiation was implemented using a UV irradiator from IST having two different UV lamps: Eta Plus M-400-U2H, Eta Plus M-400-U2HC. The exposure period was for 10 seconds with an input of 1000 mJ/cm2 of energy.
The inventive printed substrates S2.1.1 to S2.3.1 (ink T2.1.1) and S2.1.2 to S2.3.2 (ink T2.1.2) as per tables 2 and 3 were obtained and the rub fastness was determined according to ISO-105-D02:1993 and the wash fastness according to ISO 105-C06:1994.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2005 008 931.3 | Feb 2005 | DE | national |
| 10 2005 008 932.1 | Feb 2005 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2006/060229 | 2/23/2006 | WO | 00 | 8/16/2007 |
