CN-122003449-A - Heterophasic propylene copolymers with improved stiffness and stress whitening

CN122003449ACN 122003449 ACN122003449 ACN 122003449ACN-122003449-A

Abstract

The present invention relates to a composition comprising a heterophasic propylene copolymer, a process for obtaining such a composition, the use of such a composition and an article comprising such a composition.

Inventors

S. Michael Rofan
D. M.L. Segos
H. N. A. M. Ste bex - mine
A. Endiriper

Assignees

SABIC环球技术有限责任公司

Dates

Publication Date: 20260508
Application Date: 20240925
Priority Date: 20231004

Claims (15)

1. A heterophasic propylene copolymer comprising a propylene-based matrix and an ethylene copolymer as a disperse phase, wherein the amount of ethylene copolymer is from 8.5 to 12.5wt%, based on the total amount of heterophasic propylene copolymer, wherein the amount of ethylene in the ethylene copolymer is from 32.0 to 40.0wt%, based on the total amount of ethylene copolymer, wherein the heterophasic propylene copolymer has a melt flow index in the range of 15 to 35g/10min, determined according to ISO1133 using a weight of 2.16kg and a temperature of 230 ℃.
2. Heterophasic propylene copolymer according to claim 1, wherein the amount of ethylene copolymer is in the range of from 8.5 to 11.5wt%, preferably in the range of from 8.5 to 10.4wt%, more preferably in the range of from 8.5 to 9.5wt%, based on the total amount of heterophasic propylene copolymer.
3. Heterophasic propylene copolymer according to claim 1 or 2, wherein the amount of ethylene in the ethylene copolymer is in the range of 34.0 to 40.0wt%, preferably in the range of 35.0 to 39.0wt%, based on the total amount of ethylene copolymer.
4. Heterophasic propylene copolymer according to any of the preceding claims, wherein the MFI of the heterophasic propylene copolymer is in the range of 17-29g/10min, preferably in the range of 18-25g/10min, even more preferably in the range of 19-22g/10min, measured according to ISO1133 using a weight of 2.16kg and a temperature of 230 ℃.
5. The heterophasic propylene copolymer according to any of the preceding claims, wherein the heterophasic propylene copolymer comprises a nucleating agent, wherein the nucleating agent comprises talc and a cyclic dicarboxylic acid salt compound.
6. The heterophasic propylene copolymer according to claim 5, wherein the ratio between the amount of talc and the amount of cyclic dicarboxylic acid salt compound is in the range of 13-26.
7. Heterophasic propylene copolymer according to any of the preceding claims, wherein the heterophasic propylene copolymer is prepared in a process comprising a peroxide conversion step.
8. Heterophasic propylene copolymer according to any of the preceding claims, wherein the MFI of the heterophasic propylene copolymer is in the range of 6-10g/10min, preferably in the range of 7-9g/10min, measured according to ISO1133 using a weight of 2.16kg and a temperature of 230 ℃ prior to the peroxide conversion step.
9. Heterophasic propylene copolymer according to any of the preceding claims, wherein the heterophasic propylene copolymer is produced in a process comprising the step of polymerizing propylene and ethylene comonomer in the gas phase in the presence of a catalyst, wherein the catalyst comprises a procatalyst, a cocatalyst and optionally an external electron donor, wherein the procatalyst is obtainable by a process comprising the steps of: Contacting a magnesium-containing support with a halogen-containing titanium compound and an internal electron donor of formula I: I is a kind of Wherein R 1 is a secondary alkyl group and R 2 is a non-secondary alkyl group having at least 5 carbon atoms, R 2 is preferably a non-secondary alkyl group having at least 5 carbon atoms and branching at the 3-position or more; the main catalyst is prepared according to the following steps: i) Contacting compound R 4 z MgX 4 2-z with an alkoxy-OR aryloxy-containing silane compound to produce a first intermediate reaction product, i.e., solid Mg (OR a ) x X 1 2-x ), wherein R a is a linear, branched OR cyclic hydrocarbyl group independently selected from alkyl, alkenyl, aryl, aralkyl, alkoxycarbonyl, OR alkylaryl groups, and combinations of one OR more thereof, wherein the hydrocarbyl group may be substituted OR unsubstituted, may contain one OR more heteroatoms, and preferably has 1-20 carbon atoms, wherein R 4 is a linear, branched, OR cyclic hydrocarbyl group independently selected from alkyl, alkenyl, aryl, aralkyl, alkoxycarbonyl, OR alkylaryl groups, and combinations of one OR more thereof, wherein the hydrocarbyl group may be substituted OR unsubstituted, may contain one OR more heteroatoms, and preferably has 1-20 carbon atoms, R 4 is preferably butyl, wherein X 4 and X 1 are each independently selected from fluoride (F - ), chloride (Cl - ), bromide (Br 84), OR iodide (I) and z is preferably 0 to 5, z is preferably 0, 0 to 2, and is preferably an integer between 0 and 0< 2; ii) optionally contacting the solid Mg (OR a ) x X 1 2-x ) obtained in step i) with at least one activating compound selected from the group consisting of activating electron donors and metal alkoxide compounds of formula M 1 (OR b ) v-w (OR 3 ) w OR M 2 (OR b ) v-w (R 3 ) w to obtain a second intermediate, wherein M 1 is a metal selected from Ti, zr, hf, al OR Si, v is the valence state of M 1 , M 2 is metallic Si, v is the valence state of M 2 , R b and R 3 are each a linear, branched OR cyclic hydrocarbyl group independently selected from alkyl, alkenyl, aryl, aralkyl, alkoxycarbonyl OR alkylaryl groups and combinations of one OR more thereof, wherein the hydrocarbyl group may be substituted OR unsubstituted, may contain one OR more heteroatoms, and preferably has 1 to 20 carbon atoms, wherein w is less than v, v is preferably 3 OR 4; iii) Contacting the first or second intermediate reaction product obtained in step I) or ii), respectively, with a halogen-containing Ti compound and said compound represented by formula I as an internal electron donor.
10. The heterophasic propylene copolymer according to claim 9, wherein the cocatalyst is selected from trimethylaluminum, triethylaluminum, triisobutylaluminum, trihexylaluminum, diisobutylaluminum hydride, trioctylaluminum, dihexylaluminum hydride and mixtures thereof.
11. Heterophasic propylene copolymer according to any of claims 9 or 10, wherein the catalyst comprises an external donor, wherein the external donor is a silane-containing external donor, preferably wherein the external electron donor is selected from compounds having the following structure and mixtures thereof: the compound of the formula III (R 90 ) 2 N-Si(OR 91 ) 3 , The compound of the formula IV (R 92 )Si(OR 93 ) 3 , Si (OR) a ) 4-n R b n Wherein each of the R 90 、R 91 、R 92 and R 93 groups is independently a linear, branched or cyclic substituted or unsubstituted alkyl group having from 1 to 10 carbon atoms, preferably wherein each of the R 90 、R 91 、R 92 and R 93 groups is independently a linear unsubstituted alkyl group having from 1 to 8 carbon atoms, Wherein n may be 0 to 2, R a and R b each independently represent an alkyl or aryl group, optionally containing one or more heteroatoms such as O, N, S or P, having for example 1-20 carbon atoms.
12. Heterophasic propylene copolymer according to any of claims 9 to 11, wherein the molar ratio of cocatalyst to external electron donor is in the range of from 1 to 25, preferably from 1 to 15, preferably from 3 to 10, more preferably from 3.5 to 8.
13. Heterophasic propylene copolymer according to any of claims 9 to 12, wherein an activator is present in the process for preparing the procatalyst, preferably a benzamide of formula X: Wherein R 70 and R 71 are each independently selected from hydrogen or alkyl, and R 72 、R 73 、R 74 、R 75 、R 76 are each independently selected from hydrogen, heteroatom or hydrocarbyl, preferably selected from alkyl, alkenyl, aryl, aralkyl, alkoxycarbonyl or alkylaryl groups, and combinations of one or more thereof, more preferably wherein R 70 and R 71 are both methyl and wherein R 72 、R 73 、R 74 and R 75 are both hydrogen, i.e., N' -dimethylbenzamide (Ba-2 Me).
14. Heterophasic propylene copolymer according to any of the preceding claims, wherein the heterophasic propylene copolymer has an ethylene content at peak elution volume of at least 3.5mol%, preferably at least 4.5mol%, more preferably at least 5mol%, even more preferably at least 5.5mol%.
15. An article comprising the heterophasic propylene copolymer of any of the preceding claims, wherein the article is a household appliance, a furniture part or a food packaging.

Description

Heterophasic propylene copolymers with improved stiffness and stress whitening The present invention relates to a composition comprising a heterophasic propylene copolymer, a process for obtaining such a composition, the use of such a composition and an article comprising such a composition. Heterophasic propylene copolymers, also known as impact propylene copolymers or propylene block copolymers, are an important class of polymers due to their attractive mechanical properties such as impact strength over a wide temperature range and their low cost combination. These copolymers find a variety of uses, including consumer product industries (e.g., packaging and household products), automotive industry, and electrical applications, among others. For applications such as electrical applications and electrical equipment, parts made from heterophasic propylene copolymers tend to whiten after mechanical impact on the surface. This phenomenon is known as stress whitening and is undesirable for applications requiring a surface aesthetic appearance. Other properties (e.g., mechanical properties) of heterophasic propylene copolymers are often affected in improving the stress whitening properties. Thus, there remains a need for heterophasic propylene copolymers with improved stress whitening properties without deteriorating the mechanical properties. In particular, it is desirable to provide heterophasic propylene copolymers having improved stress whitening properties while having even improved stiffness without affecting low temperature impact properties. The above need is met by a heterophasic propylene copolymer comprising a propylene-based matrix and an ethylene copolymer as a disperse phase, wherein the amount of ethylene copolymer is in the range of 8.5 to 12.5 wt. -% based on the total weight of the heterophasic propylene copolymer, wherein the amount of ethylene in the ethylene copolymer is in the range of 32.0 to 40.0 wt. -% based on the total weight of the ethylene copolymer, wherein the melt flow index of the heterophasic propylene copolymer is in the range of 15 to 35g/10min, as determined according to ISO1133 using a weight of 2.16kg and a temperature of 230 ℃. Propylene-based substrates The propylene-based matrix may be a propylene homopolymer or a random copolymer of propylene with ethylene or a C4-C20 alpha-olefin. Preferably, the propylene-based matrix is a propylene homopolymer. Ethylene copolymers as disperse phase The ethylene copolymers of the present invention are preferably ethylene-alpha-olefin copolymers wherein the alpha-olefin is selected from the group consisting of C3-C8 alpha-olefins. Most preferably, the ethylene copolymer is an ethylene-propylene copolymer. The ethylene copolymer is different from the propylene-based matrix to form a dispersed phase. The amount of ethylene in the ethylene copolymer is in the range of 32.0 to 40.0wt%, preferably in the range of 34.0 to 40.0wt%, more preferably in the range of 35.0 to 39.0wt%, based on the total weight of the ethylene copolymer. Nucleating agent Preferably, the heterophasic propylene copolymer comprises a nucleating agent, wherein the nucleating agent comprises talc and a cyclic dicarboxylic acid salt compound. The cyclic dicarboxylic acid salt compound has the formula (I): such nucleation compositions are described in WO2014202603 and WO 2014202604. The Hyperform ® HPN-20ETM nucleating agent commercially available from Milliken comprises such a cis calcium hexahydrophthalate compound of formula (I) and a stearate-containing compound as an acid scavenger such as zinc stearate. Preferably, the ratio between the amount of talc and the amount of cyclic dicarboxylic acid salt compound is in the range of 13 to 26, more preferably in the range of 15 to 23, even more preferably in the range of 18 to 22. Heterophasic propylene copolymers The amount of ethylene copolymer is in the range of 8.5 to 12.5wt%, preferably in the range of 8.5 to 11.5wt%, more preferably in the range of 8.5 to 10.4wt%, most preferably in the range of 8.5 to 9.5wt%, based on the total weight of the heterophasic propylene copolymer. In the context of the present invention, the amount of ethylene copolymer in the heterophasic propylene copolymer and the amount of ethylene comonomer in the ethylene copolymer may be determined by FT-IR during the polymerization. The amount of cyclic dicarboxylic acid salt compound may be from 0.0025 to 0.1 wt.%, based on the total weight of the heterophasic propylene copolymer, preferably at least 0.004, 0.005, 0.008, 0.01 wt.% and/or at most 0.08, 0.06, 0.05, 0.03 wt.%, based on the total weight of the heterophasic propylene copolymer. The amount of talc in the polymer composition is preferably from 0.1 to 5wt%, more preferably from 0.2 to 4wt%, more preferably from 0.3 to 3wt%, most preferably from 0.3 to 1wt%, based on the total weight of the heterophasic propylene copolymer, based on the total composition. Preferably, the total amount of pr