Inks
An ink comprising a colorant, an organic solvent having a boiling point below 170° C. and a radiation-curable component of molecular weight >1000, wherein the ink contains less than 10 wt % of radiation-curable components of molecular weight 1000 or less and the ink contains less than 5 wt % water. The ink is particularly useful for printing packaging used for products intended for ingestion by humans or other animals.
1 . An ink comprising a colorant, an organic solvent having a boiling point below 170° C. and a radiation-curable component of molecular weight >1000, wherein (i) the ink contains less than 10 wt % of radiation-curable components of molecular weight 1000 or less; and (ii) the ink contains less than 5 wt % water and (iii) the ink has a viscosity of 5 to 25 cP, when measured at 25° C.
2 . (canceled)
3 . An ink according to claim 1 which further comprises a photoinitiator.
4 . An ink according to claim 1 wherein all of the ink components are approved for use on food packaging.
5 . An ink according to claim 1 wherein the radiation-curable component of molecular weight >1000 is or comprises a polyester polyacrylate of molecular weight 1,100 to 3000.
6 . An ink according to claim 1 which comprises:
(a) 0.25 to 20 wt % of colorant;
(b) at least 40 wt % of organic solvent having a boiling point below 170° C.;
(c) 2 to 65 wt % of radiation-curable component of molecular weight >1000;
(d) 0 to 20 wt % photoinitiator; and
(e) less than 10 wt % of radiation-curable components of molecular weight 1000 or less.
7 . An ink according to claim 1 which comprises:
(a) 0.5 to 5 wt % of colorant;
(b) 60 to 75 wt % of organic solvent having a boiling point below 140° C.;
(c) 10 to 35 wt % of radiation-curable component of molecular weight >1000;
(d) 1 to 10 wt % photoinitiator; and
(e) less than 5 wt % of radiation-curable components of molecular weight 1000 or less.
8 . An ink according to claim 1 wherein all of the radiation-curable components of molecular weight 1000 or less present in the ink have at least two ethylenically unsaturated groups.
9 . An ink according to claim 1 which is free from radiation-curable components of molecular weight 1000 or less.
10 . An ink according to claim 1 wherein the colorant comprises a pigment.
11 . An ink according to claim 1 wherein the organic solvent is or comprises the mono methyl ether of propylene glycol.
12 . An ink according to claim 1 wherein the organic solvent is or comprises ethanol.
13 . An ink according to claim 1 wherein the organic solvent is or comprises ethyl acetate.
14 . (canceled)
15 . (canceled)
16 . A process for printing a substrate comprising applying thereto an ink according to claim 1 by means of an ink jet printer and curing the ink.
17 . A process according to claim 16 wherein the curing is performed by a process comprising irradiating the ink with ultra-violet light.
18 . (canceled)
19 . An ink according to claim 6 which is free from radiation-curable components of molecular weight 1000 or less.
20 . An ink according to claim 7 which is free from radiation-curable components of molecular weight 1000 or less.
21 . An ink according to claim 6 wherein the organic solvent is or comprises the mono methyl ether of propylene glycol, ethanol or ethyl acetate and the colorant comprises a pigment.
22 . A process for printing a substrate comprising applying thereto an ink according to claim 6 by means of an ink jet printer and curing the ink.
23 . A process according to claim 22 wherein the curing is performed by a process comprising irradiating the ink with ultra-violet light.