# US 11,441,023 B2 · Polyethylene films and methods of making the same

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- Number: US 11,441,023 B2
- Document ID: US11441023B2
- Status: Granted
- Kind: B2
- Application number: 16/344,692
- Filed: 2018-04-27
- Published: 2021-11-25
- Granted: 2022-09-13
- Earliest claimed: 2018-04-27
- Assignees: ExxonMobil Chemical Patents Inc.
- Applicants: ExxonMobil Chemical Patents Inc.
- Inventors: Keran Chen; Yong Yang; Ling Ge; Xiao-Chuan Wang; Zhen-Yu Zhu; LeiLei Ma; Xin Hao Cai; Gregory K. Hall; Caiguo Gong; Jean-Marc C. De Koninck; Robert J. Wittenbrink
- Web page: https://patentgrep.com/patent/US11441023B2

## CPC

- C08L 23/0815: {with aliphatic 1-olefins containing one carbon-to-carbon double bond}
- B32B 27/08: of synthetic resin
- B32B 27/32: comprising polyolefins {(comprising vinyl (co)polymers or acrylic (co)polymers B32B27/30)}
- B32B 27/325: {comprising polycycloolefins}
- C08J 5/18: Manufacture of films or sheets
- B29C 48/08: flexible, e.g. films
- B29C 48/21: the layers being joined at their surfaces
- B29K 2023/0625: {LLDPE, i.e. linear low density polyethylene}
- B29K 2995/0063: Density
- B32B 2250/03: 3 layers
- B32B 2250/04: 4 layers
- B32B 2250/242: All polymers belonging to those covered by group B32B27/32
- B32B 2250/40: Symmetrical or sandwich layers, e.g. ABA, ABCBA, ABCCBA
- B32B 2307/30: having particular thermal properties
- B32B 2307/72: Density
- C08J 2323/08: Copolymers of ethene (C08J2323/16 takes precedence)
- C08J 2445/00: Characterised by the use of homopolymers or copolymers of compounds having no unsaturated aliphatic radicals in side chain, and having one or more carbon-to-carbon double bonds in a carbocyclic or in a heterocyclic ring system; Derivatives of such polymers
- C08L 2203/162: sealable films
- C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06)
- B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29)
- B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00)
- B29K: INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR {MOULDS, } REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS

## Abstract

A film, preferably, a multi-layered film, including a polymer composition, wherein the polymer composition includes: within a range from 1 wt % to 25 wt % of a cyclic olefin copolymer based on the weight of the polymer composition, and within a range from 75 wt % to 99 wt % (the remainder of material) of a polyethylene based on the weight of the polymer composition, wherein the cyclic olefin copolymer has a glass transition temperature (T.sub.g) of at least 80.degree. C. The films may be used in shrink packaging application.

## Claims

### Claim 1

A polyethylene film comprising a polymer composition, wherein the polymer composition comprises: from 75 wt % to 99 wt % of a metallocene linear low density polyethylene (LLDPE) based on the weight of the polymer composition, and from 1 wt % to 25 wt % of a cyclic olefin copolymer based on the weight of the polymer composition, wherein:
the metallocene LLDPE
comprises from 80 wt % to 99 wt % ethylene derived units and 1 wt % to 20 wt % units derived from one or more C3 to C20 α-olefins;
a hafnium concentration of greater than 5 ppm by weight;
has a density in the range of from 0.905 g/cm3 to 0.930 g/cm3;
has a melt index (I2) in the range of from 0.1 g/10 min to 2.0 g/10 min;
has a melt index ratio (MIR) in the range of from 25 to 80; and
has a molecular weight distribution (MWD) in the range of from 1.5 to 5.5; and
the cyclic olefin copolymer has a glass transition temperature (Tg) of greater than 100° C. as measured by DSC method, and wherein the cyclic olefin copolymer comprises greater than 70 wt % of or more cyclic olefin derived units by weight of the cyclic olefin copolymer.

### Claim 2 (depends on 1)

The polyethylene film of claim 1, wherein the cyclic olefin copolymer is present within a range from 5 wt % to 20 wt % based on the weight of the polymer composition.

### Claim 3 (depends on 1)

The polyethylene film of claim 1, wherein the cyclic olefin copolymer has a glass transition temperature (Tg) within a range from 110° C. 80° C. to 200° C. as measured by DSC method.

### Claim 4 (depends on 1)

The polyethylene film of claim 1, wherein the cyclic olefin derived unit is selected from C5 to C20 cyclic-olefin derived units.

### Claim 5 (depends on 1)

The polyethylene film of claim 1, wherein the cyclic olefin derived unit is selected from norbornenes, tetracyclododecene, or a combination thereof.

### Claim 6 (depends on 1)

The polyethylene film of claim 1, wherein low density polyethylene is absent from the film.

### Claim 7 (depends on 1)

The polyethylene film of claim 1, wherein the metallocene linear low density polyethylene is a copolymer comprising within a range from 0.5 to 20 wt % C4 to C12 α-olefin derived units by weight of the copolymer, the remainder of the copolymer comprising ethylene-derived units.

### Claim 8 (depends on 1)

The polyethylene film of claim 1, wherein the metallocene linear low density polyethylene has a peak melting point temperature (Tm) within a range of from 90° C. to 130° C.

### Claim 9 (depends on 1)

The polyethylene film of claim 1, wherein the metallocene linear low density polyethylene has an I2 (2.16 kg/190° C.) within a range from 0.2 g/10 min to 1.0 g/10 min.

### Claim 10 (depends on 1)

The polyethylene film of claim 1, wherein the metallocene linear low density polyethylene has the following properties:
a molecular weight of from 15,000 to 400,000 g/mol;
a molecular weight distribution (Mw/Mn) of from 1.5 to 5.0;
a hafnium to zirconium ratio (ppm/ppm) ≥1.0.

### Claim 11 (depends on 1)

The polyethylene film of claim 1, wherein the film has the following properties:
a TD shrink within a range from 10 to 40%;
a TD shrinking force within a range from 5 to 50 mN;
an MD shrink within a range from 35 to 90%;
an MD shrinking force within a range from 20 to 100 mN;
a 1% TD secant flexural modulus of at least 200 MPa;
a 1% MD secant flexural modulus of at least 200 MPa; and
a plateau seal strength of at least 14 N.

### Claim 12 (depends on 1)

The polyethylene film of claim 1, wherein the film comprises at least a core layer and at least one other layer adjacent thereto, the core layer comprising the polymer composition.

### Claim 13 (depends on 12)

The polyethylene film of claim 12, wherein the core layer is sandwiched between two skin layers.

### Claim 14 (depends on 13)

The polyethylene film of claim 13, wherein each skin layer independently comprises at least 50 wt % of a linear low density polyethylene by weight of each skin layer, wherein the linear low density polyethylene of each skin layer is the same as or different than the linear low density polyethylene of the core layer.

### Claim 15 (depends on 13)

The polyethylene film of claim 13, further comprising a sub-skin layer sandwiched between the core layer and each skin layer.

### Claim 16 (depends on 15)

The polyethylene film of claim 15, wherein each sub-skin layer independently comprises at least 50 wt % linear low density polyethylene by weight of each sub-skin layer.

### Claim 17 (depends on 12)

The polyethylene film of claim 12, wherein each skin layer comprises a metallocene polyethylene having a density within a range from 0.88 g/cm3 to 0.910 g/cm3 and a melt index in the range of from 0.2 g/10 min to 3.0 g/10 min.

### Claim 18 (depends on 12)

The polyethylene film of claim 12, having a TD shrink of at least 18%.

### Claim 19 (depends on 12)

The polyethylene film of claim 12, having a thickness at least 10% less than that of a polyethylene film free of the cyclic olefin copolymer but otherwise identical.

### Claim 20 (depends on 12)

The polyethylene film of claim 12, having a thickness at least 15% less than that of a polyethylene film free of the cyclic olefin copolymer but otherwise identical.

### Claim 21 (depends on 12)

The polyethylene film of claim 12, having a thickness at least 20% less than that of a polyethylene film free of the cyclic olefin copolymer but otherwise identical.

### Claim 22 (depends on 12)

A shrink film comprising the polyethylene film of claim 12.

### Claim 23 (depends on 12)

A process comprising extruding the polyethylene film of claim 12 at a melt temperature at the die of 238° C. or less.

### Claim 24 (depends on 12)

A process comprising extruding the polyethylene film of claim 12 at a melt pressure of 42 MPa or less.