Reactive thermally-curing and/or radiation-curing paints and their curing methods
View Patent ↗A reactive paint to be completely cured in air with binders that bear ethylenically-unsaturated groups, that can be cured by radical polymerization either thermally or both thermally and by UV light or high-energy radiation in a dual-cure method. The paint contains a combined initiator system consisting of thermal initiators and UV initiators and reactive oligomers that are formed from addition compounds of a reactant of formula (4) and a reactant of formula (5) In this formula, X=—CO—CH═CH 2 or —C n H m or —CO—C n H m . —C n H m is an aliphatic residue with 1 to 3 C atoms, whereby 0, 1, 2 or 3 X substituents are formed by —C n H m , and Y is a hydrocarbon chain of 3 to 8 atoms that can also contain heteroatoms. Also provided is a method for curing by radical polymerization. The polymerization is first started thermally under air and then is continued either thermally or photoinitiated under air or protective gas, and a use in paint systems, especially in automobile manufacturing or as a binder.
1. A paint with binders having ethylenically-unsaturated groups, the paint capable of being hardened exclusively under heat or by a combination of radical polymerization initiated by heat and radical polymerization initiated by UV light or high-energy radiation, the paint comprising:
a thermal or combined initiator system including thermal initiators and UV initiators and reactive oligomers, whereby the oligomers include addition compounds of a first reactant of the formula:
where X =—CO—CH═CH 2 or —C n H m or —CO—C n H m , whereby —C n H m is an aliphatic residue with 1 to 3 C atoms, whereby 0, 1, 2 or 3 X substituents are formed by —C n H m or —CO—C n H m ,
and a second reactant of the formula:
where Y is a hydrocarbon chain of 3 to 8 atoms, whereby the hydrocarbon chain can also contain heteroatoms.
2. The paint as recited in claim 1 wherein the thermal initiator system is formed by azo compounds.
3. The paint as recited in claim 2 wherein the azo compounds include azonitriles, cyclic or non-cyclic azoamides, azocumol or azocarboxylic acid esters, benzopinacol silyl ethers, N,N-diacyl hydroxyl amines, O-alkylated N,N-diacyl hydroxyl amines and/or O-acylated N,N-diacyl hydroxyl amines.
4. The paint as recited in claim 1 wherein the thermal initiator system comprises N,N-diacyl hydroxyl amines, O-alkylated N,N-diacyl hydroxyl amines and/or -acylated N,N-diacyl hydroxyl amines as well as coinitiator.
5. The paint as recited in claim 4 wherein the coinitiators include metal ions selected from the group of Ti, V, Cr, Mo, W, Mn, Fe, Co, Rh, Ir, Ni, Pd, Pt and/or Cu.
6. The paint as recited in claim 1 wherein the UV initiator system includes benzoin, benzophenone, thioxanthone, anthroquinone, acylphosphine oxide, acetopheonone, aromatic phosphine oxides and/or azo compounds.
7. The paint as recited in claim 1 wherein an addition compound consisting of the first and second reactants forms a majority of the binders with ethylenically unsaturated groups.
8. A method to cure a paint with binders having ethylenically unsaturated groups so as to from a paint coat, the method comprising:
curing the paint by thermally-initiated radical polymerization or a combination of thermally-initiated and UV-light initiated radical polymerization under air, or by thermally-initiated radical polymerization under protective gas, wherein the binders having the ethylenically unsaturated groups also have reactive oligomers formed by addition compounds from a first reactant of the formula:.
where X=—CO—CH═CH2 or —CnHm or —CO—CnHm, whereby —CnHm is an aliphatic residue with 1 to 3 C atoms, whereby 0, 1, 2 or 3 X substituents are formed by —CnHm or —CO—CnHm, 2 and a second reactant of the formula:
where Y is a hydrocarbon chain of 3 to 8 atoms, and the hydrocarbon chain can also contain heteroatoms.
9. The method as recited in claim 8 wherein the curing includes two process steps including a first step of thermally initiating radical polymerization under air, and second step includes thermal or ultraviolet or radiation-induced radical polymerization either carried out with access to air or under a protective gas, the paint including reactive thermal initiators from the group of azo compounds, N-diacyl hydroxyl amines, O-alkylated N,N-diacyl hydroxyl amines and/or O-acylated N,N-diacyl hydroxyl amines.
10. The method as recited in claim 8 wherein the ultraviolet-light initiators include azo compounds.