Low gloss radiation-curable compositions

1. A method of coating a substrate comprising

1) applying a non-aqueous composition to the substrate, wherein the nonaqueous composition comprises

A) an unsaturated (meth)acrylate polymer or oligomer prepared by reacting:

ai) one or more organic polyisocyanates, and

aii) one or more —NH functional compounds selected from the group consisting of 1,2-diaminopropane, 1,4-diaminobutane, 1,6-diaminohexane, 2,5-dimethylhexane, 2,2,4- and/or 2,4,4-trimethyl-1,6-diaminohexane, 1,11-diaminoundecane, 1,12-diaminododecane, 1-amino-3,3,5-trimethyl-5-aminomethyl-cyclohexane, 2,4- and/or 2,6-hexahydrotoluyiene diamine, 2,4′- and/or 4,4′-diaminodicyclohexyl methane, 3,3′-dimethyl-4,4′-diaminodicyclohexyl methane, 2,4- and/or 2,6-diaminotoluene and 2,4′- and/or 4,4′-diaminodiphenyl methane, and

aiii) 1) from 0 to about 100% by weight of a mono-, di-, tri- or poly-hydroxyl-C 1 -C 10 -alkyl or C 6 -C 10 -aryl (meth)acrylate,

2) from 0 to 100% by weight of an unsaturated polyether or polyester (meth)acrylate polyol having an OH number of from about 30 to about 500 and prepared by reacting a polyether or polyester di- or polyol with acrylic and/or methacrylic acid, or

3) a combination of 1) and 2) wherein the percents by weight of components 1) and 2) are based on the total weight of components 1) and 2) and total 100%,

at an isocyanate to hydroxyl equivalent ratio of from about 0.9:1 to about 1:0.9,

B) from about 40 to about 200% by weight of reactive diluents selected from a mono-, di-, tri- or poly C 1 -C 10 -alkyl or C 6 -C 10 -aryl{(meth) acrylates} or vinyl ethers or their mixtures,

C) from about 0.1 to about 10% by weight of one or more photoinitiators,

D) from 0 to about 90% by weight of solvent or a mixture of solvents, and

E) up to about 15% by weight of a flattener;

wherein the weight % of components B), C), D) and E) are all based on the amount of component A), and

2) exposing the coating composition to UV-A light until the composition is substantially cured to form a coating having an 85° gloss of less than or equal to 15.

2. The method of claim 1 , wherein the one or more —NH functional compounds have a number average molecular weight of from about 60 to about 600.

3. The method of claim 1 , wherein the ai) one or more organic polyisocyanates are selected from the group consisting of hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), 2,4- and/or 2,6-toluylene diisocyanate (TDI), isomeric bis (4,4′-isocyanato-cyclohexyl)methane (H 12 MDI) and an isocyanurate group-containing polyisocyanate obtained by trimerization of HDI, TDI or IPDI.

4. The method of claim 1 , wherein the coating displays greater than 100 methyl ethyl ketone double rubs.

5. The method of claim 1 , wherein the coating does not blister or delaminate after the substrate is soaked in Skydrol for 24 hours.

6. The method of claim 1 , wherein the substrate comprises 2024-T3 aluminum.

7. The method of claim 1 , wherein B) is from about 75 to about 125% by weight of reactive diluents selected from a mono-, di-, tri- or poly C 1 -C 10 -alkyl or C 6 -C 10 -aryl{(meth) acrylates} or vinyl ethers or their mixtures.

8. The method of claim 1 , wherein E) is up to about 3.5% by weight of a flattener.

9. The method of claim 1 , wherein in step 2) the coating composition is exposed to UV-A light until the composition is substantially cured to form a coating having an 85° gloss of less than or equal to 5.