# US 10,766,180 B2 · Paper-like film and process for making it

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- Number: US 10,766,180 B2
- Document ID: US10766180B2
- Status: Granted
- Kind: B2
- Application number: 15/993,851
- Filed: 2018-05-31
- Published: 2018-09-27
- Granted: 2020-09-08
- Earliest claimed: 2010-01-12
- Assignees: Greenrock, Ltd.
- Applicants: Mary Ruth Lehrter; Adam Pacelli
- Inventors: Mary Ruth Lehrter; Adam Pacelli
- Web page: https://patentgrep.com/patent/US10766180B2

## CPC

- B29C 48/0018: {combined with shaping by orienting, stretching or shrinking, e.g. film blowing (B29C48/0017 takes precedence)}
- B29C 48/08: flexible, e.g. films
- B29C 48/10: flexible, e.g. blown foils
- B29C 48/30: Extrusion nozzles or dies (extrusion characterised by the shape or cross-section of the extruded article B29C48/03)
- B29C 48/32: with annular openings, e.g. for forming tubular articles
- B29C 55/143: {firstly parallel to the direction of feed and then transversely thereto}
- B29C 67/20: for porous or cellular articles, e.g. of foam plastics, coarse-pored {(chemical aspects of working up macro-molecular substances to porous or cellular articles C08J9/00)}
- C08J 5/18: Manufacture of films or sheets
- C08J 9/228: Forming foamed products
- B29C 48/885: External treatment, e.g. by using air rings for cooling tubular films
- B29C 48/89: Internal treatment, e.g. by applying an internal cooling fluid stream
- B29C 48/912: {of tubular films}
- B29C 2948/92647: Thickness
- B29C 2948/92704: Temperature
- B29K 2023/065: {HDPE, i.e. high density polyethylene}
- B29K 2105/041: {Microporous}
- B29K 2509/00: Use of inorganic materials not provided for in groups {B29K2503/00 - B29K2507/00,} as filler
- B29K 2995/005: Oriented
- B29K 2995/0053: bi-axially
- B29L 2023/001: {Tubular films, sleeves}
- C08J 2201/03: Extrusion of the foamable blend
- C08J 2205/044: Micropores, i.e. average diameter being between 0,1 micrometer and 0,1 millimeter
- C08J 2323/06: Polyethene
- 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)
- 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)
- 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
- B29L: INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES

## Abstract

A micro-voided film comprising high density polyethylene having a molecular weight of at least about 200,000, and low aspect ratio filler having a mean particle size from about 1 to about 25 microns. The film has a thickness of from about 10 to about 75 microns and a void fraction of from about 0.60 to about 0.75. The micro-voided film is made by a process comprising extruding the composition into a film having a thickness of from about 50 to about 300 microns, and orienting the extruded film using a high stalk, blown film process. The process produces a stabilized high stalk for increasing the production rate of blown, high molecular weight polyethylene, while increasing the film's physical and mechanical properties. The high stalk can be stabilized by application of high velocity, low volume flow rate of air over the interior and exterior surfaces of the extruded film.

## Claims

### Claim 1

A micro-voided film comprising, by weight, i) from about 20% to about 60% of high density polyethylene having a molecular weight of at least about 500,000 and a melt index of less than 0.2 dg/min, and ii) from about 40% to about 80% of low aspect ratio filler having a mean particle size from about 1 to about 25 microns, wherein the weight ratio of the low aspect ratio filler to the polyethylene is at least about 0.7, said film having a having a thickness of from about 0.1 to about 20 mils and a void fraction of from 0.60 to about 0.75 and a density of from about 0.40 to about 0.70 g/cm3, wherein the voids are in the interior of the film.

### Claim 2 (depends on 1)

The micro-voided film according to claim 1 wherein the film has a void fraction of from about 0.62 to about 0.72.

### Claim 3 (depends on 1)

The micro-voided film according to claim 1 comprising from about 30% to about 50% of the high density polyethylene.

### Claim 4 (depends on 1)

The micro-voided film according to claim 1 wherein the high density polyethylene has a melt index of from about 0.02 to about 0.06 dg/min.

### Claim 5 (depends on 1)

The micro-voided film according to claim 1 wherein the low aspect ratio filler has a mean particle size of from about 1 to about 10 microns.

### Claim 6 (depends on 1)

The micro-voided film according to claim 1 comprising from about 50% to about 60% by weight of the low aspect ratio filler.

### Claim 7 (depends on 1)

The micro-voided film according to claim 1 wherein the low aspect ratio filler is calcium carbonate.

### Claim 8 (depends on 7)

The micro-voided film according to claim 7 wherein the calcium carbonate has a mean particle size of from about 3 to about 5 microns.

### Claim 9 (depends on 1)

The micro-voided film according to claim 1 further comprising up to about 2% by weight of C10-C24 organic acid.

### Claim 10 (depends on 1)

The micro-voided film according to claim 1 wherein the weight ratio of the low aspect ratio filler to the polyethylene is at least about 0.9, and the low aspect ratio filler has a mean particle size of from about 1 to about 10 microns.

### Claim 11

A micro-voided film comprising, by weight, i) from about 20% to about 60% of high density polyethylene having a molecular weight of at least about 500,000 and a melt index of less than 0.2 dg/min, and ii) from about 40% to about 80% of low aspect ratio filler having a mean particle size from about 1 to about 10 microns, wherein the weight ratio of the low aspect ratio filler to the polyethylene is at least about 0.9, said film having a having a thickness of from about 0.1 to about 20 mils and a void fraction of from 0.60 to about 0.75 and a density of from about 0.40 to about 0.70 g/cm3, wherein the voids are in the interior of the film.

### Claim 12 (depends on 11)

The micro-voided film according to claim 11 wherein the film has a void fraction of from about 0.62 to about 0.72.

### Claim 13 (depends on 11)

The micro-voided film according to claim 11 wherein the low aspect ratio filler has a mean particle size of from about 3 to about 5 microns.

### Claim 14 (depends on 13)

The micro-voided film according to claim 13 wherein the low aspect ratio filler is calcium carbonate.

### Claim 15 (depends on 14)

The micro-voided film according to claim 14 wherein the film has a void fraction of from about 0.62 to about 0.72.

### Claim 16 (depends on 15)

The micro-voided film according to claim 15 comprising from about 50% to about 60% by weight of the low aspect ratio filler.

### Claim 17 (depends on 16)

The micro-voided film according to claim 16 comprising from about 30% to about 50% of the high density polyethylene.