PRINTING INK

Abstract

This invention provides an inkjet ink comprising: an ,-unsaturated ether monomer in which the only radiation-curable functional groups present in the monomer are ,-unsaturated ether groups; a low-viscosity difunctional (meth)acrylate monomer in which the only radiation-curable functional groups present in the monomer are acrylate groups, wherein the low-viscosity difunctional (meth)acrylate monomer has a viscosity of 0.5 to 6.5 mPas at 25 C.; and a colouring agent; wherein the ink contains less than 5% by weight of water and volatile organic solvents in total, and less than 10% by weight of mono- and difunctional monomers in total, other than the ,-unsaturated ether monomer and the low-viscosity difunctional (meth)acrylate monomer, where the amounts by weight are based on the total weight of the ink, and wherein the ink has a viscosity of less than 30 mPas at 25 C.

Claims

1. An inkjet ink comprising: an ,-unsaturated ether monomer in which the only radiation-curable functional groups present in the monomer are ,-unsaturated ether groups; a low-viscosity difunctional (meth)acrylate monomer in which the only radiation-curable functional groups present in the monomer are acrylate groups, wherein the low-viscosity difunctional (meth)acrylate monomer has a viscosity of 0.5 to 6.5 mPas at 25 C.; and a colouring agent; wherein the ink contains less than 5% by weight of water and volatile organic solvents in total, and less than 3.0% by weight of mono- and difunctional monomers in total, other than the ,-unsaturated ether monomer and the low-viscosity difunctional (meth)acrylate monomer, where the amounts by weight are based on the total weight of the ink, and wherein the ink has a viscosity of less than 30 mPas at 25 C.

2. An inkjet ink as claimed in claim 1, wherein the ,-unsaturated ether monomer has a functionality of 1 to 6.

3. An inkjet ink as claimed in claim 1, wherein the ,-unsaturated ether monomer has a functionality of 2 to 4.

4. An inkjet ink as claimed in claim 1, wherein the ,-unsaturated ether monomer has a viscosity of 0.5 to 6.5 mPas at 25 C.

5. An inkjet ink as claimed in claim 1, wherein the ,-unsaturated ether monomer has a boiling point of 200 to 300 C. at 1.013 hPa.

6. An inkjet ink as claimed in claim 1, wherein the ,-unsaturated ether monomer is present at 10-50% by weight.

7. An inkjet ink as claimed in claim 1, wherein the low-viscosity difunctional (meth)acrylate monomer has a boiling point of more than 150 C. at 1.013 hPa.

8. An inkjet ink as claimed in claim 1, wherein the low-viscosity difunctional (meth)acrylate monomer is present at 10-70% by weight.

9. (canceled)

10. A cartridge containing the inkjet ink as claimed in claim 1.

11. A printed substrate having the ink as claimed in claim 1 printed thereon.

12. A printed substrate as claimed in claim 11, wherein the substrate is a food packaging.

13. A method of inkjet printing comprising inkjet printing the inkjet ink as claimed in claim 1 onto a substrate and curing the ink.

14. A method as claimed in claim 13, wherein the substrate is a food packaging.

Description

EXAMPLES

Example 1

[0050] An ink, as detailed in Table 1, was prepared by mixing the components in the given amounts. Amounts are given as weight percentages based on the total weight of the ink.

TABLE-US-00001 TABLE 1 Component Function Weight % 3,6,9,12-Tetraoxatetradeca- ,-Unsaturated 24.0 1,13-diene ether monomer 3-Methyl-1,5-pentanediol Difunctional acry- 54.5 diacrylate late monomer Modified polyester UV curable 3.0 acrylate oligomer 10-24% Solution of 2,6-bis(1,1- Stabiliser 0.5 dimethylethyl)-4-(phenylene- methylene)cyclohexa-2,5-dien-1- one in poly[oxy(methyl-1,2- ethanediyl)],alpha,alpha,alpha- 1,2,3-propanetriyltris[omega- [1-oxo-2-propen-1-yl]oxy]- 2-Hydroxy-1-[4-(2- Free-radical 3.0 hydroxyethoxy)phenyl]-2-methyl- photoinitiator 1-propanone 2-Hydroxy-1-[4-(4-(2-hydroxy-2- Free-radical 5.0 methylpropionyl)phenoxy)phenyl]- photoinitiator 2-methylpropan-1-one Phenyl bis(2,4,6-trimethylbenzoyl)- Free-radical 5.0 phosphine oxide photoinitiator Copper phthalocyanine Blue 2.4 pigment pigment Polyether-modified Surfactant 1.0 polydimethylsiloxane DISPERBYK 168 Block copolymer 1.6 pigment dispersant Total 100.00

[0051] 3,6,9,12-Tetraoxatetradeca-1,13-diene has a viscosity of 3.66 mPas at 25 C. and MPDDA has a viscosity of 5.64 mPas at 25 C. 3,6,9,12-Tetraoxatetradeca-1,13-diene has a boiling point of 252.9 C. at 1.013 hPa and a low odour and MPDDA has a boiling point of more than 180 C. at 1.013 hPa and a low odour.

[0052] The viscosity of the ink was measured using a Brookfield viscometer fitted with a thermostatically controlled cup and spindle arrangement, here a DV1 low-viscosity viscometer. The viscosity of the ink was measured as 12.1 mPas at 25 C.

[0053] The ink has a low odour. The ink has a lower odour than conventional radiation-curable inkjet inks containing typical monomers such as NVC and PEA.

[0054] The ink is suitable for indirect food packaging, such as labels. The test for the suitability for food packaging in terms of low migration is as follows. The ink is printed and cured onto a plastic substrate and tested for specific migration according to EU 10/2011 using food simulants. The ink is suitable for such use.

Example 2

[0055] An ink, as detailed in Table 2, was prepared by mixing the components in the given amounts. Amounts are given as weight percentages based on the total weight of the ink.

TABLE-US-00002 TABLE 2 Component Function Weight % 3,6,9,12-Tetraoxatetradeca- ,-Unsaturated 15.6 1,13-diene ether monomer 3-Methyl-1,5-pentanediol Difunctional acry- 22.5 diacrylate late monomer Propylidynetrimethanol, ethoxylated, Trifunctional acry- 47.1 esters with acrylic acid late monomer 10-24% Solution of 2,6-bis(1,1- Stabiliser 0.5 dimethylethyl)-4-(phenylene- methylene)cyclohexa-2,5-dien-1- one in poly[oxy(methyl-1,2- ethanediyl)],alpha,alpha,alpha- 1,2,3-propanetriyltris[omega- [1-oxo-2-propen-1-yl]oxy]- 2-Hydroxy-1-[4-(2- Free-radical 3.0 hydroxyethoxy)phenyl]-2-methyl- photoinitiator 1-propanone 2-Hydroxy-1-[4-(4-(2-hydroxy-2- Free-radical 2.0 methylpropionyl)phenoxy)phenyl]- photoinitiator 2-methylpropan-1-one Phenyl bis(2,4,6-trimethylbenzoyl)- Free-radical 4.0 phosphine oxide photoinitiator Copper phthalocyanine pigment Blue pigment 2.6 Polyether-modified Surfactant 1.0 polydimethylsiloxane DISPERBYK 168 Block copolymer 1.7 pigment dispersant Total 100.00

[0056] The viscosity of the ink was measured using a Brookfield viscometer fitted with a thermostatically controlled cup and spindle arrangement, here a DV1 low-viscosity viscometer. The viscosity of the ink was measured as 25.3 mPas at 25 C.

[0057] The ink has a low odour. The ink has a lower odour than conventional radiation-curable inkjet inks containing typical monomers such as NVC and PEA.

[0058] The ink is suitable for direct food packaging, such as containers. The test for the suitability for food packaging in terms of low migration is as follows. The ink is printed and cured onto a plastic substrate and tested for specific migration according to EU 10/2011 using food simulants. The ink is suitable for such use.