Abstract The invention disclosed is directed to a method for overcoating which includes applying to a substrate a novel photocurable lacquer composition having as essential ingredients a polyene selected from a particular group of polyenes which contain at least 2 reactive unsaturated carbon-to-carbon bonds per molecule, a polythiol containing 2 or more thiol groups per molecule and a resin component; and thereafter exposing the applied composition to actinic radiation for a period of time sufficient to photocure the applied composition to provide an overcoating. Optionally, a sensitizer may be included if desired to decrease curing time and improve efficiency. The method is particularly useful for high speed overcoating printed metal articles such as cans. Overcoatings thus provided are found to be characterized by high strength, good scratch resistance, freedom from tackiness and excellent transparency.
A PHOTOCURABLE LACQUER COMPOSITION COMPRISING (A) A POLYTHIOL COMPONENT CONTAINING AT LEAST 2 -SH GROUPS PER MOLECULE; (B) AS A POLYENE COMPONENT, THE DIADDUCT OF DIALLYL MALATE AND TOULENE DIISOCYANATE; THE MOLE RATIO OF ENE TO THIOL BEING FROM ABOUT 0.2:1 TO ABOUT 5:1; (C) FROM ABOUT 0.0005 TO ABOUT 50 PERCENT BY WEIGHT OF THE COMPOSITION OF A PHOTOCURING RATE ACCELERATOR COMPONENT; 8D) FROM 1 TO ABOUT 50 PARTS BY WEIGHT PER 100 PARTS BY WEIGHT OF THE POLYENEPOLYTHIOL COMBINATION OF A NORMALLY SOLID, SOLVENT SOLUBLE POLYESTER COMPONENT HAVING A MOLECULAR WEIGHT FROM ABOUT 500 TO ABOUT 100,000 PREPARED BY REACTING (I) A POLYBASIC ACID HAVING THE GENERAL FORMULA
Claim 2
Dependent Claim
110 words
A PHOTOCURABLE LACQUER COMPOSITION COMPRISING (A) A POLYTHIOL COMPONENT CONTAINING AT LEAST 2 -SH GROUPS PER MOLECULE; (B) AS A POLYENE COMPONENT, THE DIADDUCT OF DIALLYL MALATE AND TOULENE DIISOCYANATE; THE MOLE RATIO OF ENE TO THIOL BEING FROM ABOUT 0.2:1 TO ABOUT 5:1; (C) FROM ABOUT 0.0005 TO ABOUT 50 PERCENT BY WEIGHT OF THE COMPOSITION OF A PHOTOCURING RATE ACCELERATOR COMPONENT; 8D) FROM 1 TO ABOUT 50 PARTS BY WEIGHT PER 100 PARTS BY WEIGHT OF THE POLYENEPOLYTHIOL COMBINATION OF A NORMALLY SOLID, SOLVENT SOLUBLE POLYESTER COMPONENT HAVING A MOLECULAR WEIGHT FROM ABOUT 500 TO ABOUT 100,000 PREPARED BY REACTING (I) A POLYBASIC ACID HAVING THE GENERAL FORMULA
Claim 3
Dependent Claim
33 words
The photocurable lacquer composition of claim 1 wherein the polyester component is prepared by capping the product of the reaction of (i) or (ii) and (iii) with a member having the general formula
Claim 4
Dependent Claim
35 words
The method for overcoating which comprises applying to a substrate the lacquer composition of claim 1, and thereafter exposing the applied composition to actinic radiation for a period of time sufficient to photocure the composition.
Claim 5
Dependent Claim
34 words
The method for overcoating which comprises applying to a substrate the lacquer composition of claim 2, and thereafter exposing the applied composition actinic radiation for a period of time sufficient to photocure the composition.
Claim 6
Dependent Claim
19 words
The method of claim 3 wherein the applied composition is from about 0.1 to about 2 mils in thickness.
Claim 7
Dependent Claim
17 words
The method of claim 3 wherein the lacquer composition is applied to a substrate printed with ink.