Compatibilized thermoplastic vulcanizate compositions

Patent metadata

Field	Value
Publication number	US-11142605-B2
Application number	US-201916356844-A
Country	US
Kind code	B2
Filing date	Mar 18, 2019
Priority date	Apr 6, 2018
Publication date	Oct 12, 2021
Grant date	Oct 12, 2021

Abstract

Disclosed is the preparation of compatibilized thermoplastic vulcanizates with reduced crosslinked rubber dispersion sizes and dispersity. A cross-linkable ethylene-propylene-diene terpolymer with majority propylene (PEDM) is used to compatibilize a plastic and rubber blend of a polypropylene (PP) and an ethylene-propylene-diene terpolymer rubber, where the propylene content is less than 50 wt % (EPDM), in dynamic vulcanization and preparation of PP/EPDM thermoplastic vulcanizates. The resulting PP/EPDM thermoplastic vulcanizates typically exhibit a weight average equivalent dispersion diameter of less than 3 microns and a particle size polydispersity index (PSDI), or weight average over number average dispersion diameter, of less than 5. This reduction in crosslinked rubber dispersion size in a PP/EPDM TPV by using PEDM compatibilizers enhances the toughness of the vulcanizate product by raising both elongation to break and break stress.

First claim

The invention claimed is:

1. A thermoplastic vulcanizate comprising an isotactic polypropylene matrix phase in which a cross-linked ethylene-propylene-diene terpolymer (EPDM) is dispersed, the vulcanizate comprising the reaction product of:
a) 35 to 55 wt % of an ethylene-propylene-diene terpolymer (EPDM), wherein the EPDM comprises 50 to 80 wt% ethylene;
b) 20 to 30 wt % of isotactic polypropylene (iPP);
c) 10 to 25 wt % of a diluent;
d) 0.5 to 15 wt % of a propylene-ethylene-diene terpolymer (PEDM) compatibilizer, wherein the PEDM comprises 2 to 25 wt% ethylene and a diene content of 1 to 21 wt%; and
e) 1.5 to 3.0 wt % of curatives;
each weight percent is by weight of the combined components.

2. The thermoplastic vulcanizate of claim 1 , in which the EPDM comprises 55 to 75 wt % ethylene and 2 to 10 wt % ethylene norbornene.

3. The thermoplastic vulcanizate of claim 1 , in which the amount of PEDM is from 3 to 25 wt % of the amount of EPDM.

4. The thermoplastic vulcanizate of claim 1 , in which the MFR 2.16 at 230° C. of the PEDM is from 0.5 to 20 g/10 min.

5. The thermoplastic vulcanizate of claim 1 , in which the PEDM comprises 5 to 20 wt % ethylene and 2 to 15 wt % ethylene norbornene.

6. The thermoplastic vulcanizate of claim 1 , wherein the particle size dispersity index (PSDI) is less than 3.

Assignees

• Exxonmobil Chemical Patents Inc

Inventors

• Datta Sudhin
• Tsou Andy H
• Walker Ron
• Passino Hillary L

Classifications

• C08F2500/17

  Viscosity · CPC title

• C08L2205/03

  containing three or more polymers in a blend · CPC title

• C08L23/16

  Ethylene-propylene or ethylene-propylene-diene copolymers · CPC title

• C08L2205/22

  Mixtures comprising a continuous polymer matrix in which are dispersed crosslinked particles of another polymer · CPC title

• C08L2205/08

  containing additives to improve the compatibility between two polymers · CPC title