Process for manufacture of low emission heterophasic polypropylene

Patent metadata

Field	Value
Publication number	US-10995158-B2
Application number	US-201716468091-A
Country	US
Kind code	B2
Filing date	Dec 12, 2017
Priority date	Dec 12, 2016
Publication date	May 4, 2021
Grant date	May 4, 2021

Abstract

The invention relates to a process for the preparation of a heterophasic propylene copolymer consisting of a propylene-based matrix and a dispersed ethylene-a-olefin copolymer, comprising the steps of a) preparing the propylene-based matrix from propylene and optionally a C2 or C4-C12 α-olefin by contacting at least propylene and optionally C2 or C4-C12 a-olefin with a catalyst in a first gas-phase reactor at a temperature T1 and a pressure P1, b) subsequently preparing the dispersed ethylene-α-olefin copolymer from ethylene and a C3-C12 α-olefin by contacting the ethylene and the C3-C12 α-olefin with a catalyst in a second gas-phase reactor at a temperature T2 and a pressure P2, wherein T1-T2 is in the range from 6 to 25° C., wherein T1>T2, wherein PI and P2 are in the range from 22 to 30 bar to prepare a heterophasic propylene copolymer (A′).

First claim

The invention claimed is:

1. The process for the preparation of a heterophasic propylene copolymer consisting of a propylene-based matrix and a dispersed ethylene-α-olefin copolymer, comprising the steps of
a) preparing the propylene-based matrix from propylene and optionally a C2 or C4-C12 α-olefin by contacting at least propylene and optionally C2 or C4-C12 α-olefin with a catalyst in a first gas-phase reactor at a temperature T1 and a pressure P1,
b) subsequently preparing the dispersed ethylene-α-olefin copolymer from ethylene and a C3-C12 α-olefin by contacting the ethylene and the C3-C12 α-olefin with a catalyst in a second gas-phase reactor at a temperature T2 and a pressure P2,
wherein T1-T2 is in the range from 6 to 25° C., wherein T1>T2,
wherein P1 and P2 are in the range from 22 to 30 bar,
to prepare a heterophasic propylene copolymer (A′).

2. The process according to claim 1 , wherein the melt flow rate of the heterophasic propylene copolymer (A′) is in the range of 1.0 to 20.0 dg/min a measured according to ISO1133 (2.16 kg, 230° C.) and/or wherein the FOG value of the heterophasic propylene copolymer (A′) is at most 500 μg/g, as determined by VDA 278.

3. The process according to claim 1 , wherein the temperature T1 in the first gas-phase reactor is in the range from 60 to 75° C., or wherein the temperature T1 in the first gas-phase reactor is in the range from 70 to 85° C.

4. The process according to claim 1 , wherein in step a) the propylene-based matrix is prepared by contacting the propylene, optional C2 or C4-C12 α-olefin and a prepolymer in the first gas phase reactor, wherein the prepolymer is prepared by contacting propylene and optional α-olefin with a catalyst in a prepolymerization reactor.

5. The process according to claim 1 ,
wherein the catalyst in step a) and/or step b), is a catalyst system which comprises a Ziegler-Natta catalyst and at least one external electron donor.

6. The process according to claim 1 , wherein the heterophasic propylene copolymer consists of
(a) a propylene-based matrix,
wherein the propylene-based matrix consists of a propylene homopolymer and/or a propylene-α-olefin copolymer consisting of at least 90 wt % of propylene and at most 10 wt % of α-olefin, based on the total weight of the propylene-based matrix and
wherein the propylene-based matrix is present in an amount of 60 to 95 wt % based on the total heterophasic propylene copolymer and
(b) a dispersed ethylene-α-olefin copolymer,
wherein the dispersed ethylene-α-olefin copolymer is present in an amount of 40 to 5 wt % based on the total heterophasic propylene copolymer and
wherein the sum of the total amount of propylene-based matrix and total amount of the dispersed ethylene-α-olefin copolymer in the heterophasic propylene copolymer is 100 wt %.

7. The process according to claim 1 , wherein the amount of ethylene in the ethylene-α-olefin copolymer is in the range of 20-65 wt % based on the ethylene-α-olefin copolymer.

8. The process according to claim 1 , wherein the α-olefin in the ethylene-α-olefin copolymer is chosen from the group of α-olefins having 3 to 8 carbon atoms and any mixtures thereof.

9. The process according to claim 1 , wherein the propylene-based matrix consists of a propylene homopolymer.

10. The process according to claim 1 , further comprising the subsequent step of (II) visbreaking heterophasic propylene copolymer (A′), to obtain a heterophasic propylene copolymer (A) having a melt flow rate that is higher than the melt flow rate of the heterophasic propylene copolymer (A′) as measured according to ISO01133 (2.16 kg, 230° C.).

11. The process for preparation of a heterophasic propylene copolymer according to claim 10 , wherein the melt flow rate of the heterophasic propylene copolymer (A) as measured according to ISO1133 (2.16 kg, 230° C.) is in the range from 20 to 90 dg/min.

12. The process for preparation of a heterophasic propylene copolymer according to claim 10 , wherein the FOG value of the heterophasic propylene copolymer (A) is at most 700 μg/g, as determined by VDA 278.

13. The process for the preparation of a heterophasic propylene copolymer according to claim 10 , further comprising the step of III) reducing the FOG value of the heterophasic propylene copolymer (A′) and/or the heterophasic propylene copolymer (A) by maintaining the heterophasic propylene copolymer (A′) and/or the heterophasic propylene copolymer (A) at such temperature and for such time as to allow reduction of the FOG value to the desired level to produce a heterophasic propylene copolymer (B′) and/respectively a heterophasic propylene copolymer (B).

14. The process for the preparation of a heterophasic propylene copolymer according to claim 1 , wherein the first and second gas-phase reactors are horizontal stirred gas-phase reactors.

15. The process according to claim 5 , wherein the catalyst system is obtained by a catalyst preparation process comprising the steps of:
(A) providing a procatalyst obtainable via a process comprising the steps of:
i) contacting a compound R 4 z MgX 4 2-z with an alkoxy- or aryloxy-containing silane compound to give a first intermediate reaction product, being a solid Mg(OR 1 ) x X 1 2-x , wherein: R 4 is the same as R 1 being a linear, branched or cyclic hydrocarbyl group independently selected from alkyl, alkenyl, aryl, aralkyl, alkoxycarbonyl or alkylaryl groups, and one or more combinations thereof; wherein said hydrocarbyl group may be substituted or unsubstituted, may contain one or more heteroatoms; X 4 and X 1 are each independently selected from the group of consisting of fluoride (F—), chloride (Cl—), bromide (Br—) or iodide (I—);
ii) optionally contacting the solid Mg(OR 1 ) x X 2-x obtained in step i) with at least one activating compound selected from the group formed of activating electron donors and metal alkoxide compounds of formula M 1 (OR 2 ) v-w (OR 3 ) w or M 2 (OR 2 ) v-w (R 3 ) w , to obtain a second intermediate product; wherein M 1 is a metal selected from the group consisting of Ti, Zr, Hf, Al or Si; M 2 is a metal being Si; v is the valency of M 1 or M 2 ; R 2 and R 3 are each a linear, branched or cyclic hydrocarbyl group independently selected from alkyl, alkenyl, aryl, aralkyl, alkoxycarbonyl or alkylaryl groups, and one or more combinations thereof; wherein said hydrocarbyl group may be substituted or unsubstituted, may contain one or more heteroatoms;
iii) contacting the first or second intermediate reaction product, obtained respectively in step i) or ii), with a halogen-containing Ti-compound and optionally an internal electron donor to obtain said procatalyst;

B) contacting said procatalyst with a co-catalyst and the at least one external electron donor to form a catalyst.

16. The process according to claim 1 ,
wherein the melt flow rate of the heterophasic propylene copolymer (A′) is in the range of 1.0 to 20.0 dg/min a measured according to ISO1133 (2.16 kg, 230° C.) and wherein the FOG value of the heterophasic propylene copolymer (A′) is at 400 μg/g, as determined by VDA 278,
wherein the temperature T1 in the first gas-phase reactor is in the range from 65 to 72° C. or wherein the temperature T1 in the first gas-phase reactor is in the range from 73 to 80° C.,
wherein in step a) the propylene-based matrix is prepared by contacting the propylene, optional C2 or C4-C12 α-olefin and a prepolymer in the first gas phase reactor, wherein the prepolymer is prepared by contacting propylene and optional α-olefin with a catalyst in a prepolymerization reactor,
wherein the catalyst in step a) a

Assignees

• Sabic Global Technologies Bv

Inventors

• Lecouvet Benoit Therese Philippe
• Grein Christelle Marie Helene

Classifications

• C08F210/16

  Copolymers of ethene with alpha-alkenes, e.g. EP rubbers · CPC title

• C08L2205/02

  containing two or more polymers of the same C08L -group · CPC title

• C08L2207/02

  Heterophasic composition · CPC title

• C08F210/06

  Propene · CPC title

• C08L23/0815

  with aliphatic 1-olefins containing one carbon-to-carbon double bond · CPC title