Abrasion-resistant and low friction coating compositions

• US 5,674,951 A
• Filed: 08/03/1995
• Issued: 10/07/1997
• Est. Priority Date: 05/20/1994
• Status: Expired due to Term

• Current Assignee: Gencorp Incorporated, Aerojet-General Corporation (L3Harris Technologies, Inc.), AMPAC Fine Chemicals LLC (SK Inc.)
• Original Assignee: Gencorp Incorporated
• Inventors: Vitus, Francis Jerome, Malik, Aslam A., Kausch, Charles M., Melby, Earl G., Livigni, Russell A., Hargis, I. Glen
• Primary Examiner(s): Clark, W. Robinson H.
• Application Number:
  US08/510,686
• Time in Patent Office: 796 Days
• Field of Search: 525/410, 525/453, 525/460, 528/44, 528/45, 528/59, 528/65, 528/70
• US Class Current: 525/410
• CPC Class Codes: C08G 18/10 Prepolymer processes involving reaction of isocyanates or isothiocyanates with compounds having active hydrogen in a first reaction step
• CPC Class Codes: C08G 18/286 Oximes
• CPC Class Codes: C08G 18/50 having heteroatoms other than oxygen
• CPC Class Codes: C08G 18/5015 having fluorine atoms
• CPC Class Codes: C08G 18/6208 Hydrogenated polymers of conjugated dienes
• CPC Class Codes: C09D 175/04 Polyurethanes

Abstract

Coating compositions are disclosed which use a polyoxetane polymer having CH₂ --O---CH₂ --R_f side chains where R_f is a highly fluorinated alkyl or polyether. The coating compositions use polyisocyanates to create isocyanate terminated polymers from the poly(oxetanes) and from various polyols from alkylene oxides or polyester polyols. These can be reacted together to form block copolymer structures or can be linked together when the coating is crosslinked. A preferred method is to use blocked isocyanate groups. Another preferred embodiment is to use the composition as a abrasion resistant coating for glass run channels.

Claims

1. In an article of manufacture including a window movably and sealingly retained in an elastomeric channel having a lubricous, abrasion resistant coating on at least those portions of said channel which contact said window, the improvement wherein said coating is formed by a process comprising:

(a) reacting an excess of diisocyanate with a hydroxyl terminated polymer to produce an isocyanate terminated polymer having urethane linkages, wherein said excess is characterized as an NCO;

OH ratio of at least 2, at least 5 percent by weight of said isocyanate terminated polymer being one or more repeat units of the structure ##STR7## and wherein said repeat units are formed from one or more oxetane monomers and further wherein R is H or an alkyl of from 1 to 6 carbon atoms; and

Rf individually on each repeat unit is a linear or branched alkyl of 1 to 20 carbon atoms, a minimum of 75 percent of the H atoms of said R_f being replaced by F and optionally up to all of the remaining H atoms being replaced by I, Cl or Br;

or each R_f individually being an oxaperfluorinated polyether having from 4 to 60 carbon atoms, and n is from 1 to 5,

(b) chain extending said isocyanate terminated polymer by reacting said isocyanate terminated polymer with a poly(alkylene oxide) polyol, a polyester polyol, or a hydroxyl terminated hydrogenated diene polymer, or combinations thereof,

(c) optionally blocking unreacted isocyanate groups in said coating composition, and

(d) applying said coating composition to said channel and crosslinking the composition to form said coating.

2. In an article of manufacture according to claim 1, wherein said Rf is a linear or branched alkyl of from 1 to 20 carbon atoms and wherein excess diisocyanate from (a) is present during the reaction of said isocyanate terminated polymer with a poly(alkylene oxide) polyol, a poly(ester) polyol, or a hydroxyl terminated hydrogenated diene polymer.

3. In an article according to claim 2, wherein crosslinking of said abrasion resistant coating is accomplished with an amine crosslinking agent.

4. In an article according to claim 3, wherein the isocyanate groups of said abrasion resistant coating are chemically blocked as one step in forming said coating and wherein said repeat units of the structure ##STR8## are from 3 to 20 weight percent of said coating.

5. In an article according to claim 2, wherein said elastomeric channel comprises EPDM rubber.

6. A method of using a prepolymer polymerized from oxetane monomers to form a lubricous, abrasion resistant coating composition comprising:

(a) reacting an excess of a diisocyanate with a hydroxyl terminated prepolymer to produce an isocyanate terminated polymer having urethane links, wherein said excess is characterized by an NCO;

OH ratio of at least 2, at least 5 percent by weight of said isocyanate terminated polymer being one or more repeat units of the structure ##STR9## and wherein said repeat units are formed from one or more oxetane monomers and further wherein R is H or an alkyl of from 1 to 6 carbon atoms; and

Rf individually on each repeat unit is a linear or branched alkyl of 1 to 20 carbon atoms, a minimum of 75 percent of the H atoms of said R_f being replaced by F and optionally up to all of the remaining H atoms being replaced by I, Cl or Br;

or each Rf individually being an oxaperfluorinated polyether having from 4 to 60 carbon atoms, and n is from 1 to 5,

(b) chain extending said isocyanate terminated polymer having urethane links by reacting said isocyanate terminated polymer of (a) with a poly(alkylene oxide) polyol, a poly(ester) polyol, or a hydroxyl terminated hydrogenated diene polymer or combinations thereof forming a coating composition, and

(c) optionally blocking unreacted isocyanate groups in said coating composition.

7. A method of using a prepolymer according to claim 6, wherein said Rf is a linear or branched alkyl having from 1 to 20 carbon atoms and wherein excess diisocyanate from (a) is present during the reaction of the isocyanate terminated polymer with a poly(alkylene oxide) polyol, a poly(ester) polyol, or a hydroxyl terminated hydrogenated diene or polymer.

8. A method of using a prepolymer according to claim 7, wherein the isocyanate groups of said coating composition are chemically blocked prior to curing.

9. A method of using a prepolymer according to claim 7, wherein said coating composition is cured with an amine crosslinking agent and said repeat units of the structure ##STR10## are from 3 to 20 weight percent of said coating composition.

10. A structure adapted to sealingly interact with a movable window comprising an elastomeric portion having a lubricous, abrasion resistant coating on those portions thereof that contact with said window, wherein said coating is made by a process which comprises:

(a) reacting an excess of a diisocyanate with a hydroxyl terminated polymer to produce an isocyanate terminated polymer, wherein said excess is characterized by a NCO;

OH ratio of at least 2, at least 5 percent by weight of said isocyanate terminated polymer being one or more repeats units of the structure ##STR11## and wherein said repeat units are formed from one or more oxetane monomers and further wherein R is H or an alkyl of from 1 to 6 carbon atoms; and

Rf individually on each repeat unit is a linear or branched alkyl of 1 to 20 carbon atoms, a minimum of 75 percent of the H atoms of said Rf being replaced by F and optionally up to all of the remaining H atoms being replaced by I, Cl or Br;

or each Rf individually being an oxaperfluorinated polyether having from 4 to 60 carbon atoms, and n is from 1 to 5,

(b) chain extending said isocyanate terminated polymer by reacting with a poly(alkylene oxide) polyol, polyester polyol, or a hydroxyl terminated hydrogenated diene polymer or combinations thereof forming a chain extended product,

(c) optionally blocking unreacted isocyanate groups in the product of (b)

(d) applying the chain extended product of (b) or (c) to said structure adapted to sealingly interact with a movable window and curing the chain extended product.

11. In an elastomeric structure according to claim 10, wherein said Rf is a linear or branched alkyl of from 1 to 20 carbon atoms and wherein excess diisocyanate from (a) is present during the reaction of said isocyanate terminated polymer with a poly(alkylene oxide) polyol, a poly(ester) polyol, or a hydroxyl terminated hydrogenated diene polymer or combinations thereof.

12. In an elastomeric structure according to claim 11, wherein Rf is an oxaperfluorinated polyether.

13. In an elastomeric structure according to claim 11, wherein the isocyanate groups in the product of (b) are chemically blocked and wherein said repeat units of the structure ##STR12## are from 3 to 20 weight percent of said abrasion resistant coating.

14. In an elastomeric structure according to claim 13, wherein said coating is cured with an amine crosslinking agent.

15. In an elastomeric structure according to claim 11, wherein said elastomeric portion comprises EPDM rubber.