Chemical resistant polyurethane adhesive
A pressure sensitive adhesive composition includes a polyurethane polymer that includes the reaction product of a polyisocyanate component and a polyol component. The polyol component has a total solubility parameter ranging from 10 to 14 (cal/cm 3 ) 1/2 .
1. A pressure sensitive adhesive composition comprising a polyurethane polymer that comprises the reaction product of a polyisocyanate component and a polyol component; wherein the polyol component has a total solubility parameter ranging from 10 to 14 (cal/cm 3 ) 1/2 ;
wherein the polyurethane polymer comprises the reaction product of the polyisocyanate component, the polyol component, and a functional acid containing compound;
wherein the functional acid containing compound comprises a plurality of (HX) moieties and one or more (A) moieties, the (HX) moieties being linked to the one or more (A) moieties via an organic linking group; and
wherein the one or more (A) moieties are functional acid groups selected from —CO 2 M, —OSO 3 M, —SO 3 M, —OPO(OM) 2 , —PO(OM) 2 , wherein M is H or a cation; X is O, S, NH or NR, wherein R is an alkylene group comprising 1 to 4 carbon atoms; and wherein the organic linking group has a valency of at least 3, comprises 1 to 50 carbon atoms, optionally includes one or more tertiary nitrogen, ether oxygen, or ester oxygen atoms, and is free from isocyanate-reactive hydrogen containing groups.
2. The pressure sensitive adhesive composition of claim 1 wherein the polyol component has hydrogen bonding solubility parameter ranging from 3.5 to 6.
3. The pressure sensitive adhesive composition of claim 1 wherein the polyol component comprises a polyester polyol, a polycaprolactone polyol, a polycarbonate polyol, or a combination thereof.
4. The pressure sensitive adhesive composition of claim 1 wherein the polyol component, isocyanate component, or combination thereof comprises at least one six-membered ring structure.
5. The pressure sensitive adhesive composition of claim 1 wherein the polyol component, isocyanate component, or combination thereof comprises alkylene groups having at least 4 carbon atoms.
6. The pressure sensitive adhesive of claim 1 wherein the polyisocyanate component comprises a polyisocyanate that is a liquid at 25° C.
7. The pressure sensitive adhesive of claim 1 wherein the polyol component comprises repeat units of an ortho- or meta-phthalate, and an alkylene group comprising at least 4 carbon atoms.
8. The pressure sensitive adhesive of claim 1 , wherein acid functional groups is —CO 2 M, X is O or NH, and R 1 is an alkylene having from 1 to 7 carbon atoms.
9. The pressure sensitive adhesive of claim 1 , wherein the polyurethane comprises between 0.001 and 37 mmol acid functional groups/100 g PU.
10. The pressure sensitive adhesive composition of claim 1 wherein the composition further comprises a chemical crosslinking agent.
11. The pressure sensitive adhesive composition of claim 10 , wherein the chemical crosslinking agent comprises an organo-metallic chelating agent or aziridine.
12. A pressure sensitive adhesive composition comprising
a polyurethane polymer, wherein the polyurethane polymer comprises the reaction product of a polyisocyanate component comprising a polyisocyanate that is a liquid at 25° C.; and
a polyol component comprising repeat units of
an ortho- or meta-phthalate, and
an alkylene group comprising at least 4 carbon atoms,
wherein the pressure sensitive adhesive has a G′ less than 1 MPa at 25° C. and a frequency of 1 hertz.
13. The pressure sensitive adhesive composition of claim 12 wherein polyisocyanate component comprises an aliphatic polyisocyanate, an aromatic polyisocyanate, or a mixture thereof.
14. The pressure sensitive adhesive composition of claim 12 wherein the polyisocyanate component comprises an ortho- or meta-aromatic diisocyanate.
15. The pressure sensitive adhesive composition of claim 12 wherein the polyol component comprises a polymeric polyester polyol having the structure
wherein R 1 is independently an alkylene group comprising at least 4 carbon atoms, n is at least 2, and
the ester group substituents are bonded to the ring at an ortho- or meta-position.
16. The pressure sensitive adhesive composition of claim 12 wherein the polyol component further comprises a multi-functional polyol having greater than two hydroxyl groups.
17. The pressure sensitive adhesive composition of claim 12 wherein the polyisocyanate component further comprises a multi-functional isocyanate having greater than two isocyanate groups.
18. The pressure sensitive adhesive composition of claim 12 wherein either or both of the multi-functional polyol and multi-functional isocyanate are present in an amount of no greater than 30 mol %.
19. The pressure sensitive adhesive composition of claim 12 wherein the polyurethane has a weight average molecular weight of at least 20,000 g/mole.
20. The pressure sensitive adhesive composition of claim 12 wherein the adhesive has a 180° peel to stainless steel of at least 10N/dm at a peel rate of 300 mm/minute after a 24 hour dwell time at 25° C.
21. The pressure sensitive adhesive composition of claim 12 wherein the adhesive has a 180° peel to stainless steel of at least 10N/dm at a peel rate of 300 mm/minute after a 72 hour dwell time at 65° C. and 90% relative humidity.
22. The pressure sensitive adhesive composition of claim 12 wherein the pressure sensitive adhesive does not dissolve in oleic acid or a 70% isopropyl alcohol aqueous solution after 8 hours at 70° C.
23. The pressure sensitive adhesive composition of claim 12 wherein the pressure sensitive adhesive has a chemical resistance rating of at least 3 for oleic acid and a 70% isopropyl alcohol aqueous solution after 8 hours at 70° C.
24. A laminating tape comprising
a substrate; and
a layer of a pressure sensitive adhesive composition according to claim 12 disposed on a major surface of the substrate.