Thermosetting acrylic powder coating composition of a polyblend of acrylic polymer having a high glass transition temperature and an acrylic polymer having a low glass transition temperature and a cross-linking agent

Claim 1

A THERMOSETTING ACRYLIC POLYMER POWDER COATING COMPOSITION COMPRISING FINELY DIVIDED PARTICLES HAVING A PARTICLE SIZE OF 1-100 MICRONS; WHEREIN THE POWDER PARTICLES ARE IN INTIMATELY MIXED BLEND OF FILM C-FORMING CONSTIITUENTS CONSISTING ESSENTIALLY OF A/ 40-75 PERCENT BY WEIGHT OF A HARD ACRYLIC POLYMER CONSISTING ESSENTIALLY OF 1. 80-95 PERCENT BY WEIGHT, BASED ON THE WEIGHT OF THE HARD ACRYLIC POLYMER, OF METHYL METHACRYLATE, 2. 3-10 PERCENT BY WEIGHT, BASED ON THE WEIGHT OF THE HARD ACRYLIC POLYMER, OF AN ALKYL METHYLACRYLATE OR AN ALKYL ACRYLATE HAVING 2-14 CARBON ATOMS IN THE ALKYL GROUPS, 3. 2-17 PERCENT BY WEIGHT, BASED ON THE WEIGHT OF THE HARD ACRYLIC POLYMER, OF A HYDROXYALKYL ACRYLATE OR HHYDROXYALKYL METHACRYLATE HAVING 2-4 CARBON ATOMS IN THE ALKYL GROUPS OR MIXTURES THEREOF; WHEREIN THE HARD ACRYLIC POLYMER HAS A GLASS TRANSITION TEMPERATURE OF ABOUT 75* TO 90*C. AND A NUMBER AVERAGE MOLECULAR WEIGHT OF 3,000-10,000; B. 10-25 PERCENT BY WEIGHT OF A SOFT ACRYLIC POLYMER CONSISTING ESSENTIALLY OF 1. 40-60 PERCENT BY WEIGHT, BASED ON THE WEIGHT OF THE SOFT ACRYLIC POLYMER, OF METHYLMETHACRYLATE, 2. 30-56 PERCENT BY WEIGHT, BASED ON THE WEIGHT OF THE SOFT ACRYLIC POLYMER, OF AN ALKYL ACRYLATE OR AN ALKYL METHACRYLATE HAVING 2-14 CARBON ATOMS IN THE ALKYL GROUPS, 3. 4-10 PERCENT BY WEIGHT, BASED ON THE WEIGHT OF THE SOFT ACRYLIC POLYMER, OF A HYDROXY ALKYL ACRYLATE OR A HYDROXY ALKYL METHACRYLATE HAVING 2-4 CARBON ATOMS IN THE ALKYL GROUPS OR MIXTURES THEREOF; WHEREIN THE SOFT ACRYLIC POLYMER HAS A GLASS TRANSITION TEMPERATURE OF ABOUT 0* TO 30*C. AND A NUMBER AVERAGE MOLECULAR WEIGHT OF ABOUT 8,0000-20,000; C. 7-19.98 PERCENT BY WEIGHT OF AN ALKYLATED MELAMINE FORMALDEHYDE RESIN HAVING 1-8 CARBON ATOMS IN THE ALKYL GROUP; D. 6-15 PERCENT BY WEIGHT OF DIHYDROXY FUNCTIONAL PLASTICIZER OF A POLYESTER ESIN HAVING A MOLECULAR WEIGHT OF 520-4,000 OR A POLYCAROLACTONE HAVING A MOLECULAR WEIGHT OF 520-2,000; ANDP E. 0.02-2.0 PERCENT BY WEIGHT OF A BLOCKED ACID CATALYST OF A BLOCKED PARATOLUENE SULFONIC ACID CATALYST.