# US 10,766,981 B2 · Bimodal polypropylenes and method of making same

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- Number: US 10,766,981 B2
- Document ID: US10766981B2
- Status: Granted
- Kind: B2
- Application number: 15/746,965
- Filed: 2015-08-04
- Published: 2018-09-13
- Granted: 2020-09-08
- Earliest claimed: 2014-09-30
- Assignees: ExxonMobil Chemical Patents Inc.
- Applicants: ExxonMobil Chemical Patents Inc.
- Inventors: Rohan A. Hule; Sudhin Datta; Yi Ping Ni
- Web page: https://patentgrep.com/patent/US10766981B2

## CPC

- C08F 110/06: Propene
- C08L 23/12: Polypropene
- C08F 2500/05: Bimodal or multimodal molecular weight distribution
- C08F 2500/12: Melt flow index or melt flow ratio
- C08F 2500/17: Viscosity
- C08L 2203/30: used for thermoforming
- C08L 2205/025: containing two or more polymers of the same hierarchy C08L, and differing only in parameters such as density, comonomer content, molecular weight, structure
- C08L 2205/035: containing four or more polymers in a blend
- C08F: MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06)

## Abstract

Bimodal polypropylene compositions and a process to form melt blended bimodal polypropylene compositions comprising combining at least two polypropylenes in at least a two-pass process, and forming a bimodal polypropylene composition having a Flexural Modulus (190° C., 1% secant) of at least 1700 MPa, as well as one or more other selected properties. These compositions are suitable for thermoformed articles and injection molded articles, any of which may be foamed.

## Claims

### Claim 1

A process to form bimodal polypropylene compositions comprising:
1) combining at least two polypropylenes comprising:
a) a high molecular weight polypropylene, HMW PP, having a weight average molecular weight (Mw) of 300,000 g/mole or more, and a MWD within the range from 2.0 to 4.5; and
b) a low molecular weight polypropylene, LMW PP, having a weight average molecular weight (Mw) of 300,000 g/mole or less, and a MWD within the range from 2.0 to 4.5, in at least a two-pass process, and
2) forming a bimodal polypropylene composition having a Flexural Modulus (190° C., 1% secant) of at least 1700 MPa, wherein the Flexural Modulus of the bimodal polypropylene composition is equal to or at least 5% greater than the HMW PP Flexural Modulus alone, and the bimodal polypropylene composition has one or more of the following characteristics:
(a) a melt flow rate (MFRbPP, 230° C., 2.16 kg) within the range from 2 g/10 min to 200 g/10 min; and/or
(b) a combined molecular weight distribution (MwbPP/MnbPP, MWDbPP) within the range from 2.5 to 20.0, and/or
(c) a ΔMw, the Mw difference between at least two polypropylenes, of at least 100,000 g/mole; and
3) injection molding or blow molding articles from the bimodal polypropylene composition.

### Claim 2 (depends on 1)

The process of claim 1, wherein at least one of the polypropylenes is formed from a single-site catalyst.

### Claim 3 (depends on 1)

The process of claim 1, wherein the at least two polypropylenes comprise:
30-60 wt % of the BMW PP, wherein the weight average molecular weight (Mw) is 400,000 g/mole or more; and
40-70 wt % of the LMW PP, wherein the weight average molecular weight (Mw) is 200,000 g/mole or less;
wherein the ΔMw between the BMW PP and the LMW PP is at least 200,000 g/mol.

### Claim 4 (depends on 1)

The process of claim 1, wherein the combining takes place at a Tmelt within the range from 140° C. to 230° C.

### Claim 5 (depends on 1)

The process of claim 1, wherein the process is a melt blending process that takes place in an extruder having a feeder zone and a die zone, wherein a temperature gradient is provided from a feeder zone to a die zone of at least +20° C.

### Claim 6 (depends on 5)

A process comprising forming pellets or an article from the melt blended bPP produced by the process of claim 5, wherein processing of the bimodal polypropylene to form pellets or an article takes place at a Shear Viscosity (η2500, 190° C., using Capillary Rheology) of less than 60 Pa·sec at 2500 l/sec.

### Claim 7 (depends on 1)

The process of claim 1, wherein the bimodal polypropylene composition has a Flexural Modulus within the range from 1700 MPa to 3000 MPa.

### Claim 8 (depends on 1)

The process of claim 1, wherein the Flexural Modulus of the bimodal polypropylene composition is equal to or at least 15% greater than the HMW component Flexural Modulus alone.

### Claim 9 (depends on 1)

The process of claim 1, comprising combining within the range from 5 wt % to 65 wt % (based upon weight of the blend) of the HMW PP and within the range from 35 wt % to 95 wt % (based upon weight of the blend) of the LMW PP.

### Claim 10 (depends on 1)

The process of claim 1, wherein the two-pass process comprises:
a) combining 5 wt % to 65 wt % (based upon weight of the combined components) of the HMW PP, with 35 wt % to 95 wt % (based upon weight of the combined components) of the LMW PP, where the difference in Mw between the HMW PP and the LMW PP is at least 100,000 g/mol;
b) melt blending in an extruder the components in a) at a melt Tmelt within the range from 140° C. to 230° C.;
c) introducing the first melt blend from b) into the same or different extruder and further melt blending the solid blend, where the extruder at a Tmelt within the range from 140° C. to 230° C.; and
d) isolating the blend produced in step c) to produce the bimodal polypropylene composition.

### Claim 11 (depends on 10)

The process of claim 10, further comprising cooling the blend produced in step b) to produce the first melt blend which is then used in step c).

### Claim 12 (depends on 1)

The process of claim 1, wherein the articles from the bimodal polypropylene composition are blow molded.

### Claim 13 (depends on 1)

The process of claim 1, wherein the articles from the bimodal polypropylene composition are injection molded.

### Claim 14 (depends on 1)

The process of claim 1, wherein the at least two polypropylenes comprise:
30-60 wt % of the HMW PP, wherein the weight average molecular weight (Mw) is 400,000 g/mole or more, and the MWD within the range from 2.0 to 4.5; and
40-70 wt % of the LMW PP, wherein the weight average molecular weight (Mw) is 200,000 g/mole or less, and the MWD within the range from 2.0 to 4.5;
wherein the ΔMw between the BMW PP and the LMW PP is at least 200,000 g/mol.

### Claim 15

A polypropylene composition comprising:
a) 35 wt. % to 60 wt. % of a high molecular weight polypropylene having a weight average molecular weight of 400,000 g/mole or more, and a MWD within the range from 2.0 to 4.5; and
b) 40 wt. % to 65 wt. % of a low molecular weight polypropylene having a weight average molecular weight of 300,000 g/mole or less, and a MWD within the range from 2.0 to 4.5, based on a combined weight of the high and low molecular weight polypropylene,
said polypropylene composition having a Flexural Modulus (190° C., 1% secant) of at least 1700 MPa, wherein the Flexural Modulus of the polypropylene composition is equal to or at least 5% greater than a Flexural Modulus of the high molecular weight polypropylene alone, and wherein the high molecular weight polypropylene and the low molecular weight composition have been melt blended together and the weight average molecular weight of the high molecular weight polypropylene is at least 200,000 g/mol greater than weight average molecular weight of the low molecular weight polypropylene.

### Claim 16 (depends on 15)

The polypropylene compositions of claim 15,
wherein the low molecular weight polypropylene has a weight average molecular weight (Mw) of 200,000 g/mole or less.

### Claim 17 (depends on 15)

The polypropylene composition of claim 15, having a Heat Deflection Temperature (HDT) of greater than 95° C.

### Claim 18 (depends on 15)

The polypropylene composition of claim 15, having a melting point temperature Tm2 within the range from 150° C. to 165° C.

### Claim 19 (depends on 15)

The polypropylene composition of claim 15, having a Flexural Modulus within the range from 1700 MPa to 3000 Mpa.

### Claim 20 (depends on 15)

The polypropylene composition of claim 15, wherein the Flexural Modulus is equal to or at least 15% greater than the Flexural Modulus of the high molecular weight polypropylene alone.

### Claim 21 (depends on 15)

The polypropylene compositions of claim 15, wherein the polypropylene composition has a melt flow rate (MFRbPP, 230° C., 2.16 kg) within the range from 2 g/10 min to 200 g/10 min.

### Claim 22 (depends on 15)

The polypropylene composition of claim 15, wherein the weight average molecular weight of the high molecular weight polypropylene is within a range from 400,000 g/mole to 1,000,000 g/mole.

### Claim 23 (depends on 15)

The polypropylene composition of claim 15, wherein the weight average molecular weight of the low molecular weight polypropylene is within a range from 50,000 g/mole to 200,000 g/mole.

### Claim 24 (depends on 15)

The polypropylene composition of claim 15, having a Shear Viscosity (190° C., Capillary Rheology) η2500 value of less than 60 Pa·sec at 2500 l/sec.

### Claim 25 (depends on 15)

The polypropylene composition of claim 15, having a ratio of Complex Viscosities (190° C., SAOS) of zero shear up and at a shear frequency of 200 rad/sec η200 (ηo/η200) of greater than 10.

### Claim 26 (depends on 15)

The polypropylene composition of claim 15, formed by a two-pass melt blending process.

### Claim 27 (depends on 15)

The polypropylene composition of claim 15, wherein at least one of the high molecular weight and low molecular weight polypropylenes is formed from a single-site catalyst.

### Claim 28 (depends on 15)

The polypropylene composition of claim 15, further comprising another polymeric component selected from the group consisting of styrenic block copolymers, ethylene-propylene elastomers, ethylene-based plastomers, propylene-based elastomers, propylene-based impact copolymers, and combinations thereof.

### Claim 29 (depends on 15)

Thermoformed articles, injection molded articles, or blow molded articles, foamed or non-foamed, comprising the polypropylene composition of claim 15.

### Claim 30 (depends on 15)

An injection molded article comprising the polypropylene composition of claim 15.

### Claim 31 (depends on 15)

A blow molded article comprising the polypropylene composition of claim 15.