Interactive Coating for End Printing

Abstract

Thermochromic coatings are improved by mixing thermochromic capsules with polymer resins in a manner that imparts shelf stability to flowable precursors that may be cured quickly using dodecylbenzenesulfonic acid and/or other acid catalysts to form relatively hard coatings that are capable of withstanding machine operations, such as the operations needed to make beverage can lids, bottle caps, pull tabs and the like.

What is claimed: 
     
         1 . A reversible thermochromic coating for use in can and coil coatings, said reversible thermochromic coating comprising,
 a reversible thermochromic pigment in an amount from 1% to 50% by weight of the coating, and   a vehicle forming the balance of the coating,   the vehicle including a resin selected from the group consisting of polyester, polyurethane, urethane, acrylic acid and acrylate resins, and combinations thereof; and   a curing agent comprising benzenesulfonic acid substituted at any position with at least one alkyl group of from about 1 to about 20 carbons.   
     
     
         2 . The coating of  claim 1  wherein the curing agent is dodecylbenzenesulfonic acid. 
     
     
         3 . The coating of  claim 1  wherein the curing agent is selected from the group consisting of A 40S; ABS 100; Ambicat LE 4476; B 121; B 121 (surfactant); Bio-Soft S 100; Bio-Soft S 101; Biosoft S 126; Calsoft LAS 99; Cat 6000; Catalyst 600; Catalyst 6000; Cycat 600; DBS; Dobanic acid; Dodecylbenzenesulphonic acid; E 7256; Elfan WA Sulphonic Acid; LAS 99; Laurylbenzenesulfonic acid; Lipon LH 500; Maranil DBS; Marlon AS 3; Nacconol 98SA; Nacure 5074; Nacure 5076; Nansa 1042; Nansa 1042P; Nansa SSA; Neopelex FS; Neopelex GS; Neopelex GS-P; P 3 Vetralat; Pelex F 25; Polystep A 13; Rhodacal SSA/A; Richonic Acid B; S 100; Soft Osen 5S; Sulfosoft; Sulframin 1298; Sulframin Acid 1298; Taycacure AC 430; Taycapower L 120D; Taycapower L 121; Taycapower L 122; Ufacid K; Witco 1298; Witco 1298 Acid Soft; Witco 1298 Soft Acid; Witconic 1298 Hard Acid; Witconic 1298 Soft Acid; blocked or unblocked acid catalysts; Decotherm 255e, Nacure 2500, cycat 4040, cycat 4045, cycat 600, paratoluene sulfonic acid, amine blocked paratoluenesulfonic acid; and n-dodecylbenzenesulfonic acid. 
     
     
         4 . The coating of  claim 1  wherein the vehicle further comprises a surfactant to facilitate dispersion of the pigment in the vehicle. 
     
     
         5 . The coating of  claim 1  wherein the vehicle further comprises a curing agent/accelerator to speed curing of the resin. 
     
     
         6 . The coating of  claim 1  wherein the vehicle further comprises a wax to improve surface properties of the coating when cured. 
     
     
         7 . The coating of  claim 1  wherein the vehicle further comprises a solvent affecting rheological properties of the coating. 
     
     
         8 . The coating of  claim 7  wherein the solvent is a nonpolar solvent. 
     
     
         9 . The coating of  claim 8  wherein the coating is premixed and exhibits reversible thermochromic behavior for at least 14 days when stored at a temperature of about 20° C. 
     
     
         10 . The coating of  claim 8  wherein the coating is premixed and exhibits reversible thermochromic behavior for at least 45 days when stored at a temperature of about 20° C. 
     
     
         11 . The coating of  claim 1 , wherein said thermochromic pigment contains microcapsules formed with an acid catalyst effective to enhance the inherent stability in polar, low molecular weight solvents having a molecular weight of about less than 100 g/mol. 
     
     
         12 . The coating of  claim 1 , wherein said thermochromic microcapsule achieves color change between a temperature of about −5° C. and up to about 65° C. 
     
     
         13 . The coating of  claim 1 , wherein said thermochromic coating is selected from the group of colors consisting essentially of a color selected by combining of one or more of the following reversible thermochromic colors: yellow, magenta, cyan, black. 
     
     
         14 . The coating of  claim 1 , wherein a color change effect obtained by mixing thermochromic colors with conventional pigments. 
     
     
         15 . The coating of  claim 1 , wherein a change from a colored state to a different colored state upon cooling to the reactive temperature. 
     
     
         16 . The coating of  claim 1 , wherein a change from a colorless state to a colored state upon cooling to the reactive temperature. 
     
     
         17 . The coating of  claim 1  containing 5 to 40% by weight of thermochromic microcapsule solids. 
     
     
         18 . The coating of  claim 1  containing 40 to 70% by weight resin. 
     
     
         19 . The coating of  claim 1  containing 0 to 5% by weight of thermochromic microcapsule wetting agents. 
     
     
         20 . The coating of  claim 1  containing 0 to 25% by weight of a curing agent. 
     
     
         21 . The coating of  claim 1  containing 40 to 70% by weight of polyester resin, polyurethane resin or fatty acid modified alkyds. 
     
     
         22 . The coating of  claim 1  containing 20 to 40% by weight of a thermochromic pigment. 
     
     
         23 . The coating of  claim 1  containing 1 to 10% by weight of an acid catalyst curing agent. 
     
     
         24 . The coating of  claim 1  containing 30% thermochromic pigment, 60% polyester resin, and 10% acid catalyst. 
     
     
         25 . The coating of  claim 24  wherein said polyester resin is Decotherm 290E, and wherein said acid catalyst is Cycat 600. 
     
     
         26 . The coating of  claim 1  containing 30% thermochromic pigment, 60% polyurethane resin, and 10% acid catalyst. 
     
     
         27 . The coating of  claim 1  containing 1 to 10% by weight of an accelerator and/or catalyst. 
     
     
         28 . The coating of  claim 7  containing 0 to 5% by weight of wax. 
     
     
         29 . The coating of  claim 7  containing 0 to 50% by weight of solvent(s). 
     
     
         30 . The coating of  claim 1  wherein said resin is curable at elevated temperatures or using an ultraviolet curing system. 
     
     
         31 . A method of using the coating of  claim 1 , wherein the coating is applied by roller coating to roll stock aluminum and the roll stock aluminum is subsequently formed into one or more beverage can components selected from the group consisting of beverage can ends, beverage can tabs, bottle caps, and/or beverage container closures. 
     
     
         32 . The method of  claim 31  wherein the roll stock aluminum a coiled sheet of aluminum alloy 5182-H48. 
     
     
         33 . The method of  claim 32  wherein said reversible thermochromic coating of  claim 1  wherein the beverage can component has a color activation temperature effective for use as an indicator of beverage temperature. 
     
     
         34 . The method of  claim 33  wherein the coating of  claim 1  is applied in one or more coats to yield a dried film thickness ranging from 1 mg/in 2  up to 5.5 mg/in 2 , thereby controlling observed color intensity. 
     
     
         35 . The method of  claim 34  wherein the coating cures in less than about 20 seconds. 
     
     
         36 . A method of end printing cans using the coating of  claim 1 , wherein the coating is applied to the end of a can by coating means. 
     
     
         37 . The method of  claim 36  wherein the coating cures in less than about 20 seconds.