Radiation-curable compounds
The invention relates to low-viscosity formulations of radiation-curable compounds, to processes for preparing them, to their use, and to inks, printing-inks, and print varnishes that comprise them.
1. A process for preparing an incorporable photoinitiator of low viscosity, the process comprising
1) synthesizing a polyurethane A comprising, in reacted form:
(a) an organic polyisocyanate comprising an allophanate group and having an NCO functionality of at least 2, synthesized from an aliphatic C 4 to C 20 alkylene diisocyanate,
(b) a compound having at least one isocyanate-reactive group and at least one radically polymerizable unsaturated group,
(c) a photoinitiator having at least one isocyanate-reactive group,
(d) optionally a further diisocyanate, polyisocyanate, or both, which is different from (a),
(e) optionally a compound having at least two isocyanate-reactive groups, and
(f) optionally a compound having precisely one isocyanate-reactive group,
under an anhydrous condition, in the presence of less than 1000 ppm by weight of a compound comprising at least one element selected from the group consisting of bismuth, zinc and titanium, to obtain the polyurethane A; and
2) mixing the polyurethane A with 0.5% to 4% by weight of water, based on an amount of the polyurethane A.
2. The process according to claim 1 , wherein component (b) is bonded via allophanate groups to component (a).
3. The process according to claim 2 , wherein an amount of allophanate groups, calculated as C 2 N 2 HO 3 =101 g/mol, is 1% to 28% by weight.
4. The process according to claim 1 , wherein the compound (c) has at least one formula selected from the group consisting of
in which
R 3 , R 4 , and R 5 each independently of one another are hydrogen, an alkyl group comprising 1 to 4 carbon atoms or an alkyloxy group comprising 1 to 4 carbon atoms,
p is 0 or an integer from 1 to 10, and
Y i for i=1 to p independently of one another are selected from the group consisting of —CH 2 —CH 2 —O—, —CH 2 —CH(CH 3 )—O—, —CH(CH 3 )—CH 2 —O—, —CH 2 —C(CH 3 ) 2 —O—, —C(CH 3 ) 2 —CH 2 —O—, —CH 2 —CHVin-O—, —CHVin-CH 2 —O—, —CH 2 —CHPh-O—, and —CHPh-CH 2 —O—.
5. The process according to claim 1 , wherein the compound (c) is selected from the group consisting of 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1-hydroxycyclohexyl phenyl ketone, 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)benzyl]phenyl}-2-methylpropan-1-one, 2-hydroxy-1-[4-[hydroxy[4-(2-hydroxy-2-methylpropanoyl)phenyl]methyl]phenyl]-2-methyl-propan-1-one, [4-[3-(4-benzoylphenoxy)-2-hydroxypropoxy]phenyl]phenylmethanone, benzoin, benzoin isobutyl ether, benzoin tetrahydropyranyl ether, benzoin methyl ether, benzoin ethyl ether, benzoin butyl ether, benzoin isopropyl ether, 7H-benzoin methyl ether, 2-hydroxy-2,2-dimethylacetophenone, and 1-hydroxyacetophenone.
6. The process according to claim 1 , wherein the polyurethane A comprises, in reacted form, a compound (f) comprising an alkoxylated aliphatic alcohol having a formula
R 9 —O—[—Z i —] q —H
in which
R 9 is an alkyl radical having 1 to 20 carbon atoms,
q is a positive integer from 1 to 15, and
Z i for i=1 to q independently of one another may be are selected from the group consisting of —CH 2 —CH 2 —O—, —CH 2 —CH(CH 3 )—O—, —CH(CH 3 )—CH 2 —O—, —CH 2 —C(CH 3 ) 2 —O—, —C(CH 3 ) 2 —CH 2 —O—, —CH 2 —CHVin-O—, —CHVin-CH 2 —O—, —CH 2 —CHPh-O—, and —CHPh-CH 2 —O—.
7. The process according to claim 1 , wherein compound comprising at least one element selected from the group consisting of bismuth, zinc and titanium is selected from the group consisting of a zinc carboxylate of a carboxylate which has at least six carbon atoms, a bismuth carboxylate of a carboxylate which has at least six carbon atoms, and a titanium tetraalcoholate, Ti(OR) 4 , of an alcohol ROH having 1 to 8 carbon atoms.
8. The process according to claim 1 , wherein the polyurethane A comprises, in reacted form, (d) the further diisocyanate, polyisocyanate, or both, which is different from (a).
9. The process according to claim 1 , wherein the polyurethane A comprises, in reacted form, (e) the compound having at least two isocyanate-reactive groups.
10. The process according to claim 1 , wherein the polyurethane A comprises, in reacted form, (f) the compound having precisely one isocyanate-reactive group.
11. The process according to claim 1 , wherein the polyurethane A comprises, in reacted form, (d) and (e).
12. The process according to claim 1 , wherein the polyurethane A comprises, in reacted form, (d) and (f).
13. The process according to claim 1 , wherein the polyurethane A comprises, in reacted form, (e) and (f).
14. The process according to claim 1 , wherein the polyurethane A comprises, in reacted form, (d), (e) and (f).
15. The process according to claim 1 , wherein the incorporable photoinitiator has a viscosity of not more than 400 Pas measured according to DIN EN ISO 3219, shear rate D, 100 s −1 , at 23° C.
16. The process according to claim 1 , wherein the incorporable photoinitiator has a viscosity of less than 300 Pas measured according to DIN EN ISO 3219, shear rate D, 100 s −1 , at 23° C.
17. The process according to claim 1 , wherein the incorporable photoinitiator has a viscosity of less than 250 Pas measured according to DIN EN ISO 3219, shear rate D, 100 s −1 , at 23° C.
18. The process according to claim 1 , wherein the incorporable photoinitiator has a viscosity of less than 200 Pas measured according to DIN EN ISO 3219, shear rate D, 100 s −1 , at 23° C.