Ethylene copolymer having enhanced film properties

Patent metadata

Field	Value
Publication number	US-10676552-B2
Application number	US-201815985039-A
Country	US
Kind code	B2
Filing date	May 21, 2018
Priority date	May 30, 2017
Publication date	Jun 9, 2020
Grant date	Jun 9, 2020

Abstract

The disclosure provides an ethylene copolymer having a density of from 0.912 g/cm3 to 0.925 g/cm3, a melt flow ratio (I21/I2) of from 20 to 30, and a normal comonomer distribution profile in a GPC-FTIR analysis, wherein the normal comonomer distribution profile has a slope of from −3.5 to −7.5, where the slope is defined as the number of short chain branches per 1000 carbons at a molecular weight of 300,000 minus the number of short chain branches per 1000 carbons at a molecular weight of 30,000. The ethylene copolymers have improved bulk density and when made into film, provide good physical properties.

First claim

What is claimed is:

1. A blown film comprising an ethylene copolymer comprising ethylene and an alpha olefin having 3-8 carbon atoms, the ethylene copolymer having a density of from 0.912 g/cm 3 to 0.925 g/cm 3 , a melt index (I 2 ) of from 0.1 g/10 min to 5.0 g/10 min, a melt flow ratio (I 21 /I 2 ) of from 20 to 30, and a normal comonomer distribution profile in a GPC-FTIR analysis, wherein the normal comonomer distribution profile has a slope of from −3.5 to −7.5, where the slope is defined as the number of short chain branches per 1000 carbons at a molecular weight of 300,000 minus the number of short chain branches per 1000 carbons at a molecular weight of 30,000.

2. The blown film of claim 1 wherein the ethylene copolymer has a characteristic composition distribution parameter, β Tp1 which satisfies the relationship:
β Tp1 ≤22750-1400 (SCB/1000C−2.5×I 2 ); wherein β Tp1 has dimensions of (Daltons/° C.).

3. The blown film of claim 1 wherein the ethylene copolymer has a characteristic composition transition parameter, Φ Tp1→Tp2 which satisfies the relationship: Φ Tp1→Tp2 ≤4230-140 [SCB/1000C+0.5×I 21 /I 2 )−2×I 2 ]; wherein Φ Tp1→Tp2 has dimensions of (Daltons/° C.).

4. The blown film of claim 1 wherein the ethylene copolymer has a molecular weight distribution (M w /M n ) of from 2.5 to 4.0.

5. The blown film of claim 1 wherein the ethylene copolymer has a multimodal profile in a TREF analysis, the multimodal profile comprising two intensity maxima occurring at elution temperatures Tp1 and Tp2, wherein Tp1 is between
80° C. and 90° C. and Tp2 is between 90° C. and 100° C.

6. The blown film of claim 1 wherein less than
0.5 wt % of the ethylene copolymer elutes at a temperature of above 100° C. in a TREF analysis.

7. The blown film of claim 1 wherein the alpha-olefin is 1-hexene.

8. The blown film of claim 1 wherein the ethylene copolymer has a CDBI 50 of from 20 wt % to 40 wt %.

9. The blown film of claim 1 wherein the ethylene copolymer has a melt index (I 2 ) of from 0.2 to 2.0 g/10 min.

10. The blown film of claim 1 , having a 0.8 mil thickness at a die gap of 85 mil and a blow up ratio (BUR) of 2:1, has a dart impact of greater than 350 g/mil.

11. The blown film of claim 1 wherein the ethylene copolymer is made with a Ziegler-Natta catalyst.

12. The blown film of claim 1 , wherein the ethylene copolymer is made in a gas phase polymerization process.

13. The blown film of claim 11 wherein the Ziegler-Natta catalyst comprises:
a) a calcined silica support;
b) a first aluminum compound having the formula Al 1 R b (OR) a X 3−(a+b) , wherein a+b=3 and b≥1,
R is a C 1-10 alkyl radical, and X is a chlorine atom;
c) a magnesium compound having the formula Mg(R 5 ) 2 where each R 5 is independently selected from the group consisting of C 1-8 alkyl radicals;
d) a reactive organic halide selected from the group consisting of CCl 4 and C 3-6 secondary and tertiary alkyl chlorides or a mixture thereof;
e) a titanium compound having the formula Ti(OR 2 ) c X d wherein R 2 is selected from the group consisting of a C 1-4 alkyl radical, and a C 6-10 aromatic radical, X is selected from the group consisting of a chlorine atom and a bromine atom, c is 0 or an integer up to 4 and d is 0 or an integer up to 4 and the sum of c+d is the valence of the Ti atom;
f) an electron donor wherein the electron donor is a trialkylamine compound; and
g) a second aluminum compound having the formula Al 2 R b (OR) a X 3−(a+b) , wherein
a+b=3 and b≥1, R is a C 1-10 alkyl radical, and X is a chlorine atom.

14. The blown film of claim 1 , wherein the ethylene copolymer has a bulk density of greater than 25 lbs/ft 3 .

15. The blown film of claim 1 having a machine direction tear of ≥400 g/mil when the film has a thickness of 0.8 mil and is made at a die gap of 85 mil and a blow up ratio (BUR) of 2:1.

Assignees

• Nova Chem Int Sa

Inventors

• Lam Patrick
• Ker Victoria
• Kelly Mark

Classifications

• C08F2500/10

  Short chain branches · CPC title

• C08F2500/12

  Melt flow index or melt flow ratio · CPC title

• C08F2500/08

  Low density, i.e. < 0.91 g/cm3 · CPC title

• C08F210/16 Primary

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

• C08F4/6425

  containing magnesium · CPC title