POLYURETHANE BEING SUITABLE AS BINDER FOR A MODULAR PRINTING INK SYSTEM

Abstract

The present invention relates to a polyurethane, which is particularly suitable as binder for a printing ink, which is obtainable by reacting: a) a polyol component including: i) at least one polytetramethylene glycol, ii) at least one diol having a molecular weight of not more than 200 g/mol being different from polytetramethylene glycol, iii) at least one trivalent or higher-valent alcohol having a molecular weight of not more than 6000 g/mol, b) an isocyanate component including at least one organic diisocyanate compound and c) at least one di-functional amine compound and at least one mono-functional amine compound.

Claims

1. A polyurethane being suitable as binder for a printing ink, which is obtainable by reacting: a) a polyol component including: i) at least one polytetramethylene glycol, ii) at least one diol having a molecular weight of not more than 200 g/mol being different from polytetramethylene glycol, iii) at least one trivalent or higher-valent alcohol having a molecular weight of not more than 6,000 g/mol, b) an isocyanate component including at least one organic diisocyanate compound and c) at least one di-functional amine compound and at least one mono-functional amine compound wherein i) the polyurethane does not contain any polyester group or wherein ii) the polyurethane cures physically and not chemically.

2. The polyurethane in accordance with claim 1, wherein the polyurethane comprises 5 to 60 mol % glycol units.

3. The polyurethane in accordance with claim 1, wherein the at least one diol having a molecular weight of not more than 200 g/mol is selected from the group consisting of ethylene glycol, propylene glycol, butane diol, pentane diol, hexane diol, heptane diol, octane diol, nonane diol, decane diol, 1,3-methylpropane diol, cyclohexanedimethanol, neopentylglycol, 2-methyl-2,4pentanediol, 1,4-cyclohexanediol and mixtures of two or more of the aforementioned compounds, wherein the polyurethane comprises 2 to 50 mol-%, diol units.

4. The polyurethane in accordance with claim 1, wherein the at least one trivalent or higher-valent alcohol having a molecular weight of not more than 6,000 g/mol is selected from the group consisting of trimethylolpropane, di-trimethylolpropane, glycerol, pentaerythritol, di-pentaerythritol, alkoxylated pentaerythritol, alkoxylated di-pentaerythritol, xylitol, inositol (cyclohexanehexol) and mixtures of two or more of the aforementioned compounds, wherein the polyurethane comprises 0.2 to 5 mol % trivalent alcohol units.

5. The polyurethane in accordance with claim 1, wherein the molar ratio of trivalent or higher-valent alcohol units to polytetramethylene glycol units in the polyurethane is 1:5 to 1:20.

6. The polyurethane in accordance with claim 1, wherein the molar ratio of isocyanate units to polyol units in the polyurethane is 1:1 to 1:2.

7. The polyurethane in accordance with claim 1, wherein the di-functional amine compound is selected from the group consisting of isophorone diamine, diethyl toluenediamine, dimethyl toluenediamine, hexamethylenediamine, tetramethylenediamine, ethylenediamine, phenylenediamine, diaminocyclohexane, diaminodicyclohexane, diaminodiphenylmethane, polyether diamines, 1,3-diaminopropane, 1,5-diaminopentane, 1,2-diaminopropane, diphenyl ethylene diamin, 2,5-diaminotoluene, triethylenediamine, 1,8-diaminooctane, 1,10-diaminodecane, 2,4-diaminodiphenyl-methane, 1,3-propanediamine, 2,2-dimethyl-, 1,5-pentanediamine, 2-methyl-, 1,2-benzenediamine, 3(or 4)-methyl-, 4-aminoheptane, and mixtures of two or more of the aforementioned compounds, wherein the molar ratio of the di-functional amine compound to the isocyanate compound is 1:1 to 1:10.

8. The polyurethane in accordance with claim 1, wherein the mono-functional amine compound is selected from the group consisting of methylamine, ethylamine, propylamine, butylamine, pentylamin, hexylamin, heptylamin, octylamine, nonylamin, n-dodecylamine, cyclohexylamine, cyclopentylamine, anilin, phenethylamine, 2-methyl-2-benzylamine, 2-ethyl-hexylamine, 1,1,3,3-tetramethyl-butylamine and mixtures of two or more of the aforementioned compounds, wherein the molar ratio of the mono-functional amine compound to the isocyanate compounds is 1:0.5 to 1:10.

9. The polyurethane in accordance with claim 1, wherein the polyurethane has a weight-average molecular weight determined by gel permeation chromatography of 5,000 to 200,000 g/mol.

10. The polyurethane in accordance with claim 1, wherein the polyurethane is obtainable by first reacting: a) a polyol component including: i) 30 to 70 mol-% of at least one polytetramethylene glycol having a weight-average molecular weight of 500 to 5,000 g/mol, ii) 25 to 65 mol-% of at least one diol selected from the group consisting of ethylene glycol, propylene glycol, butane diol, pentane diol, hexane diol, heptane diol, octane diol, nonane diol, decane diol, 1,3-methylpropane diol, cyclohexanedimethanol, neopentylglycol, 2-methyl-2,4pentanediol, 1,4-cyclohexanediol and mixtures of two or more of the aforementioned compounds, iii) 2 to 10 mol-% of at least one trivalent or higher-valent alcohol selected from the group consisting of trimethylolpropane, di-trimethylolpropane, glycerol, pentaerythritol, di-pentaerythritol, alkoxylated pentaerythritol, alkoxylated di-pentaerythritol, xylitol, inositol (cyclohexanehexol) and mixtures of two or more of the aforementioned compounds and b) an isocyanate component including at least one organic diisocyanate compound selected from the group consisting of toluene-2,4-diisocyanate, methylendiphenylisocyanate, hexamethylene diisocyanate, 1,5-naphthalene diisocyanate, isophorone diisocyanate, tetramethylxylylene diisocyanate, cyclohexane diisocyanate (CHDI), polymeric diphenylmethandiisocyanate (PMDI), p-phenylene diisocyanate (PPDI)and mixtures of two or more of the aforementioned compounds, wherein the molar ratio of isocyanate compound(s) to the sum of polyol compounds is 1:1.4 to 1:1.8, and then reacting the so obtained prepolymer with a di-functional amine compound and a mono-functional amine compound, wherein the di-functional amine compound is selected from the group consisting of isophorone diamine, diethyl toluenediamine, dimethyl toluenediamine, hexamethylenediamine, tetramethylenediamine, ethylenediamine, phenylenediamine, diaminocyclohexane, diaminodicyclohexane, diaminodiphenylmethane, Polyether diamines, 1,3-diaminopropane, 1,5-diaminopentane, 1,2-diaminopropane, diphenyl ethylene diamin, 2,5-diaminotoluene, triethylenediamine, 1,8-diaminooctane, 1,10-diaminodecane, 2,4-diaminodiphenyl-methane, 1,3-propanediamine, 2,2-dimethyl-, 1,5-pentanediamine, 2-methyl-, 1,2-benzenediamine, 3(or 4)-methyl-, 4-aminoheptane, and mixtures of two or more of the aforementioned compounds, wherein the mono-functional amine compound is selected from the group consisting of methylamine, ethylamine, propylamine, butylamine, pentylamin, hexylamin, heptylamin, octylamine, nonylamin, n-dodecylamine, cyclohexylamine, cyclopentylamine, anilin, phenethylamine, 2-methyl-2-benzylamine, 2-ethyl-hexylamine, 1,1,3,3-tetramethyl-butylamine and mixtures of two or more of the aforementioned compounds, wherein the molar ratio of the di-functional amine compound to the isocyanate compound is 1:4 to 1:7, and, wherein the molar ratio of the mono-functional amine compound to the isocyanate compounds is 1:2 to 1:5.

11. A method for preparing a polyurethane in accordance with claim 1 comprising reacting: a) a polyol component including: i) at least one polytetramethylene glycol, ii) at least one diol being different from polytetramethylene glycol, iii) at least one trivalent or higher-valent alcohol, b) an isocyanate component including at least one organic diisocyanate compound and c) at least one di-functional amine compound and at least one mono-functional amine compound.

12. A pigment concentrate, which contains: 5 to 30% by weight of at least one polyurethane in accordance with claim 1, 10 to 30% by weight of at least one pigment, solvent and optionally at least one grinding auxiliary, wherein the sum of all components is 100% by weight.

13. A system additive for preparing a printing ink containing at least one polyurethane in accordance with claim 1 and at least one solvent, wherein the solvent is any of the below: a) a mixture of ethanol and ethyl acetate or b) a mixture of i) ethyl acetate and ii) ethoxypropanol and iii) propylacetate and/or ethanol or c) ethyl acetate.

14. A kit in particular for preparing a printing ink comprising: at least one pigment concentrate in accordance with claim 12, at least one system additive in accordance with claim 13 and additional solvent to achieve print viscosity.

15. A printing ink in particular for flexographic printing containing: a pigment concentrate in accordance with claim 12 and at least one system additive in accordance with claim 13, wherein the solvent in the system additive is a mixture of ethanol and ethyl acetate, and/or a pigment concentrate in accordance with claim 12 and at least one system additive in accordance with claim 13, wherein the solvent in the system additive is a mixture of i) ethyl acetate and ii) ethoxypropanol and iii) propylacetate and/or ethanol, and/or a pigment concentrate in accordance with claim 12 and at least one system additive in accordance with claim 13, wherein the solvent in the system additive is ethyl acetate.

Description

EXAMPLE 1

[0096] For the production of 100 kg of a polyurethane according to the present invention a vessel was charged with 18.2 kg PTMEG-2000, stirred and heated up to 110 C. to 115 C. Then, 0,23 kg Di-TMP were added, stirred for another 15 minutes and vacuum was applied for half an hour. The heating was switched off so that the mixture could cool down to 55 to 60 C. 7.45 kg IPDI were added and stirred, then 0.9 kg butandiol were added. After 10 minutes of stirring 0.007 kg of tetrabutyltitanate were added. The temperature raised automatically up to about 90 C. The temperature should not exceed 95 C. The mixture was kept at this temperature for at least 2.5 hours and stirred well until the NCO content was 2.8-3.2% as determined by titration. The mixture was allowed to cool down to 85 C., then 35 kg ethylacetate and 0.137 kg of water were added. After 10 minutes another 35.596 kg ethylacetate were added. A mixture of 1.28 kg IPDI, 0.04 kg monoethanolamin and 1 kg of ethylacetate was prepared and added stepwise to the reaction vessel when the temperature in the vessel was 50 to 65 C. After 30 minutes temperature were raised to 65 to 70 C. and 0.16 kg of monoethanolamine were added slowly during 15 minutes to the mixture. The amine value of the prepared product should be 1.4-1.7 mg KOH/g, and can be determined by titration. Perhaps longer reaction time at 70 to 75 C. may be required. After cooling the polyurethane was ready for usage.

[0097] Suitable amounts of the used compounds are listed in the following table:

TABLE-US-00001 Preferred Most Preferred RM Quantity min. max min. CODE Description Mw in g Qty. Qty. Qty. max Qty C-476 PTMEG- 2000 18.2 15.000 25.000 15.000 20.000 2000 C-036 1,4 Butandiol 90 0.9 0.500 1.500 0.500 1.000 C-284 Di TMP 250 0.23 0.100 0.400 0.200 0.300 C-219 IPDI 222 7.45 5.000 10.000 6.000 8.000 A-036 Tetra- 340 0.007 butyltitanate S-035 Ethyl Acetate 71.396 C-230 IPDA 170 1.28 0.500 1.500 0.700 1.300 A-017 MEA 61 0.4 0.100 1.500 0.300 1.0 Water Water 18 0.137 Total 100

EXAMPLE 2

[0098] Another polyurethane was prepared according to the process described for example 1 with compounds and amounts listed in the following table:

TABLE-US-00002 Preferred Most Preferred RM max. min max. CODE Discription Qty gms min Qty. Qty. Qty. Qty. C- PPG-1000 18.02 15 25 15 20 327/495 C-306 1,3 MPD 0.8 0.5 1.2 0.6 1 C-284 Di TMP 0.18 0.1 0.25 0.15 0.2 C-219 IPDI 8.68 8 9.5 8.5 9 A-036 BT 0.01 S-035 Ethyl Acetate 70.5 C-230 IPDA 1.05 0.5 1.5 0.8 1.2 A-017 MEA 0.62 0.3 1.2 0.5 1 Water Water 0.14 Total 100

EXAMPLE 3

[0099] Another polyurethane according to the invention was also prepared following the synthesis description of example 1. The used compounds and suitable ranges are listed in the following table:

TABLE-US-00003 Preferred Most Preferred RM max. min max. CODE Discription Qty gms min Qty. Qty. Qty. Qty. C-476 PTMEG- 19.43 15 25 15 20 2000 C-036 1,4 Butendiol 0.81 0.5 1.2 0.6 1 C-005 TMP 0.14 0.1 0.2 0.1 0.15 C-219 IPDI 6.91 6 8 6.5 7.5 A-036 BT 0.01 S-035 Ethyl Acetate 70.95 C-230 IPDA 0.91 0.5 1.5 0.8 1.2 A-017 MEA 0.7 0.3 1.2 0.5 1 Water Water 0.14 Total 100