Aminoplast-curable film-forming compositions providing films having resistance to acid etching

• US 6,245,855 B1
• Filed: 11/12/1997
• Issued: 06/12/2001
• Est. Priority Date: 10/30/1992
• Status: Expired due to Term

• Current Assignee: PPG Industries Ohio Incorporated (Nouryon BV)
• Original Assignee: PPG Industries Ohio Incorporated (Nouryon BV)
• Inventors: Swarup, Shanti, Singer, Debra L., McCollum, Gregory J., Mayo, Michael A.
• Primary Examiner(s): Wu, David W.
• Assistant Examiner(s): ZALUKAEVA, TATYANA
• Application Number:
  US08/968,105
• Time in Patent Office: 1,308 Days
• Field of Search: 525/119, 525/120, 525/157, 525/162, 525/163
• US Class Current: 525/157
• CPC Class Codes: C08F 8/30 Introducing nitrogen atoms or nitrogen-containing groups
• CPC Class Codes: C08L 2666/14 Macromolecular compounds according to C08L59/00 - C08L87/00; Derivatives thereof
• CPC Class Codes: C08L 2666/16 Addition or condensation polymers of aldehydes or ketones according to C08L59/00 - C08L61/00; Derivatives thereof
• CPC Class Codes: C08L 61/20 Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen with aminophenols C08L61/04
• CPC Class Codes: C08L 61/32 Modified amine-aldehyde condensates
• CPC Class Codes: C09D 133/062 Copolymers with monomers not covered by C09D133/06
• CPC Class Codes: C09D 167/00 Coating compositions based on polyesters obtained by reactions forming a carboxylic ester link in the main chain based on polyester-amides C09D177/12; based on polyester-imides C09D179/08; Coating compositions based on derivatives of such polymers
• CPC Class Codes: C09D 201/06 containing oxygen atoms C09D201/025 takes precedence

Abstract

An aminoplast-curable film-forming composition is disclosed. The film-forming composition is a crosslinkable composition comprising (1) a material containing a plurality of carbamate and/or urea functional groups and (2) an aminoplast crosslinking agent. The composition provides a coating with improved acid etch resistance, making the coating particularly useful as an automotive clear coat.

Claims

1. A curable film-forming composition comprising (1) an acrylic polymer containing a plurality of terminal or pendant groups of the structure:

where R is H or alkyl of 1-18 carbon atoms, the acrylic (co)polymer having an equivalent weight less than 5,000 based on equivalents of said terminal or pendant group; and

(2) an aminoplast crosslinking agent containing methylol and/or methylol ether groups;

said film-forming composition being crosslinkable via direct reaction of said pendant or terminal groups with said methylol and/or methylol ether groups;

said film-forming composition being further characterized as having a calculated hydroxyl value less than 50 based on solid weight of said film-forming composition, excluding any hydroxyl functionality associated with N-methylol groups so as to result in a crosslinked coating which has a substantial number of urethane crosslinks arising from said direct reaction of pendant or terminal groups with said methylol and/or methylol ether groups giving said crosslinked coating a high level of acid etch resistance.

2. The composition of claim 1 in which the acrylic polymer has an equivalent weight within the range of about 140 to 2,500 based on equivalents of said terminal or pendant groups.

3. The composition of claim 1 in which the aminoplast is a condensate of melamine with formaldehyde and optionally an alcohol containing from 1 to 6 carbon atoms.

4. The composition of claim 1 wherein the equivalent ratio of said pendant or terminal groups to methylol or methylol ether groups is from 0.5 to 2:

1 and is sufficient to form a crosslinked film.

5. The composition of claim 1 wherein the material is present in the film-forming composition in amounts of 50 to 90 percent by weight based on weight of resin solids in the film-forming composition.

6. The composition of claim 1 wherein the aminoplast is present in the film-forming composition in amounts of 10 to 50 percent based on weight of resin solids in the film-forming composition.