Elastomeric blends

• US 5,051,480 A
• Filed: 10/16/1989
• Issued: 09/24/1991
• Est. Priority Date: 10/16/1989
• Status: Expired due to Fees

• Current Assignee: Flexsys International L.P.
• Original Assignee: Monsanto Company (Bayer AG)
• Inventors: Coran, Aubert Y.
• Primary Examiner(s): NOT, DEFINED
• Application Number:
  US07/421,431
• Time in Patent Office: 708 Days
• Field of Search: 525/227, 525/230, 524/520, 524/533, 524/506, 523/351
• US Class Current: 525/227
• CPC Class Codes: C08G 77/24 halogen-containing groups
• CPC Class Codes: C08L 15/005 Hydrogenated nitrile rubber
• CPC Class Codes: C08L 21/00 Compositions of unspecified rubbers
• CPC Class Codes: C08L 2666/02 Organic macromolecular compounds, natural resins, waxes or and bituminous materials
• CPC Class Codes: C08L 2666/04 Macromolecular compounds according to groups C08L7/00 - C08L49/00, or C08L55/00 - C08L57/00; Derivatives thereof
• CPC Class Codes: C08L 33/08 Homopolymers or copolymers of acrylic acid esters
• CPC Class Codes: C08L 83/04 Polysiloxanes
• CPC Class Codes: C08L 9/02 Copolymers with acrylonitrile

Abstract

Compositions of acrylic rubber and another rubber which can be nitrile rubber, hydrogenated nitrile rubber, fluoroelastomer, silicon rubber, or fluorosilicone rubber are described, in which the acrylic rubber can be uncured or at least partially crosslinked. The compositions are millable and processable and, by the addition of curatives for the nitrile rubber, hydroganted nitrile rubber, fluoroelastomer, siloicone rubber, or fluorosilicone rubber, can be further crosslinked to become vulcanizates which exhibit excellent resistance to the effects of hot air, hot oil, and ozone. The acrylic rubber is a copolymers from alkyl acrylate monomer which copolymer contains no crosslinking sites other than acrylate ester sites, and can be crosslinked by reaction with a paraffinic alcohol.

Claims

1. An elastomeric blend comprising 10-90 parts by weight of (A) an elastomeric polymer from one or more alkyl acrylate monomers which polymer contains no crosslinking sites other than acrylate ester sites and, correspondingly, 90-10 parts by weight of (B) another elastomeric polymer which is nitrile rubber, hydrogenated nitrile rubber, or a fluoroelastomer.

2. The blend of claim 1, comprising 20-60 parts of (A) and, correspondingly, 80-40 parts of (B), wherein the alkyl acrylate monomers are ethyl acrylate or mixtures comprising ethyl acrylate and butyl acrylate.

3. The blend of claim 2 comprising 25-50 parts of (A) and, correspondingly, 75-50 parts of (B).

4. The blend of claim 3 containing curatives for (B).

5. The blend of claim 4 in which (B) is vulcanized.

6. The blend of claim 1 in which (A) is in the form of vulcanized or crosslinked particles of average diameter below 50 micrometers.

7. The blend of claim 6 comprising 25-65 parts by weight of (A) and, correspondingly, 75-35 parts by weight of (B), in which the particles of (A) have an average diameter below 20 micrometers.

8. The blend of claim 7 comprising 40-60 parts by weight of (A) and, correspondingly, 60-40 parts by weight of (B), in which the particles of (A) have an average diameter below 10 micrometers.

9. The blend of claim 7 in which (B) is nitrile rubber, hydrogenated nitrile rubber or a fluoroelastomer.

10. The blend of claim 9 in which the particles of (A) have an average diameter below 5 microns.

11. The blend of claim 6 in which (B) is nitrile rubber or hydrogenated nitrile rubber.

12. A method for preparing a millable, vulcanizable elastomeric composition by the steps of:

i) forming a mixture comprising 10-90 parts by weight of (A) one or more elastomeric polymers from alkyl acrylate monomer which polymers contain no crosslinking sites other than acrylate ester sites, and, correspondingly,90-10 parts by weight of (B) another elastomeric polymer which is nitrile rubber, hydrogenated nitrile rubber, a fluoroelastomer, a silicone rubber or a fluorosilicone rubber and, ii) masticating the mixture at a temperature between 140° and

240°

C. in the presence of a diol for a time sufficient to achieve at least partial vulcanization of (A).

13. The method of claim 12 wherein a transesterification catalyst is present with the diol.

14. The method of claim 13 wherein the diol contains 2 to 12 carbon atoms.

15. The method of claim 14 wherein the catalyst is a metal salt.

16. The method of claim 15 wherein the diol is 1,6-hexanediol and the catalyst is selected from dibutyltin dilaurate and dibutyltin diacetate.

17. The method of claim 14 wherein the catalyst is poly(dioctyltin maleate).

18. The method of claim 14 wherein (B) is nitrile rubber, hydrogenated nitrile rubber or a fluoroelastomer.

19. The product of the method of claim 12.