Two component waterborne polyurethane coatings for anti-graffiti application

• US 7,875,672 B2
• Filed: 08/22/2008
• Issued: 01/25/2011
• Est. Priority Date: 08/24/2007
• Status: Active Grant

• Current Assignee: Rhodia Operations (Solvac SA)
• Original Assignee: Perstorp France
• Inventors: Rosen, Richard P., Wu, Xiaodong
• Primary Examiner(s): NILAND, PATRICK DENNIS
• Application Number:
  US12/196,620
• Publication Number:
  US 20090054570A1
• Time in Patent Office: 886 Days
• Field of Search: 524/507, 524/589, 524/590, 524/591, 524/839, 524/840, 525/123, 525/455, 525/125, 525/127, 525/129
• US Class Current: 524/507
• CPC Class Codes: C08G 18/6216 Polymers of alpha-beta ethylenically unsaturated carboxylic acids or of derivatives thereof
• CPC Class Codes: C08G 18/6279 containing fluorine atoms
• CPC Class Codes: C08G 18/706 the liquid medium being water
• CPC Class Codes: C08L 25/14 with unsaturated esters
• CPC Class Codes: C08L 33/14 of esters containing halogen, nitrogen, sulfur, or oxygen atoms in addition to the carboxy oxygen
• CPC Class Codes: C09D 175/04 Polyurethanes

Abstract

Two component (2K) waterborne polyurethane coating compositions which when cured achieve excellent anti-graffiti properties at low VOC level (below 100 g/L) are disclosed. The composition comprises (A) a fluorinated polyol and optionally a non-fluorinated polyol; and (B), a blend of polyisocyanates comprising a hydrophilically modified trimer of hexamethylene diisocyanate (HDT) and a hydrophilic ally modified trimer of isophorone diisocyanate (IPDT). The glass transition temperature of the ambient cured coatings, crosslinked network structure, and fluorine content at the surface enable excellent anti-graffiti properties. The waterborn coatings of the invention have excellent recoatability and exceptional chemical resistance.

Claims

1. An anti-graffiti coating composition comprising the reaction product of (A) a polyol blend comprising a fluorinated acrylic polyol and a non-fluorinated acrylic polyol, wherein the fluorinated polyol is a hydroxyl functional styrene acrylic copolymer emulsion and the non-fluorinated polyol is a hydroxyl functional styrene acrylic copolymer emulsion;

and (B) a blend of polyisocyanates comprising (i) a hydrophilically modified trimer of hexamethylene diisocyanate (HDT) and (ii) a hydrophilically modified trimer of isophorone diisocyanate (IPDT).

2. The coating composition of claim 1 having a VOC below 100 g/L.

3. The coating composition of claim 1 wherein the fluorinated polyol comprises 1 to 40% by weight of the polyol blend.

4. The coating composition of claim 1 wherein the molar ratio of isocyanate units in the blend of polyisocyanates to hydroxyl units in the polyol blend is about 1 to 3.

5. The coating composition of claim 1 wherein said HDT and IPDT are surfactant based hydrophilic polyisocyanate emulsions in water, auto dispersible in aqueous phase, with at least one surfactant containing an anionic functional group, a countercation and, a polyethylene glycol chain fragment having one or more ethyleneoxy units, wherein the anionic functional group of said surfactant corresponds to the following formula:

6. The coating composition of claim 1 further comprising a solvent.

7. The coating composition of claim 1 wherein said fluorinated polyol has a glass transition temperature of from 10°

C. to 80°

C.