# US 5,702,786 A · Process for preparing thermoplastic polyolefin resin articles of reduced hydrocarbon permeability

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- Number: US 5,702,786 A
- Document ID: US5702786A
- Status: Granted
- Kind: A
- Application number: 08/635,693
- Filed: 1996-04-22
- Granted: 1997-12-30
- Earliest claimed: 1996-04-22
- Assignees: Greif Bros. Corporation
- Inventors: Ronald T. Robichaud
- Web page: https://patentgrep.com/patent/US5702786A

## CPC

- B29C 48/3363: {using a layered die, e.g. stacked discs}
- B29C 48/09: Articles with cross-sections having partially or fully enclosed cavities, e.g. pipes or channels
- B29C 48/10: flexible, e.g. blown foils
- B29C 48/21: the layers being joined at their surfaces
- B29C 48/92: Measuring, controlling or regulating
- B29C 49/041: {using an accumulator head}
- B29C 2948/92647: Thickness
- B29C 2948/92666: Distortion, shrinkage, dilatation, swell or warpage
- Y10T 428/1352: Polymer or resin containing [i.e., natural or synthetic]
- 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)
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A process is described for improving the hydrocarbon solvent impermeability of polyethylene resin based containers. The process employs a thermal profile during thermal molding, which creates a crystalline barrier adjacent one surface of the container. The barrier enhances impermeability of the container.

## Claims

### Claim 1

A process for preparing polyethylene resin containing articles of reduced hydrocarbon permeability, which comprises;
providing a thermoplastic resin composition, which comprises;
a major proportion of a polyethylene resin;
a minor proportion of polyvinylidene fluoride: and
a binding proportion of aluminum stearate;
feeding the resin composition to a heating zone, said zone being maintained at a temperature above the first order phase transition temperature of the polyethylene, whereby said fed composition is thermally plasticized;
continuously passing the plasticized composition to a shaping zone wherein said plasticized composition is shaped in the form of an article having first and second surfaces;
cooling the article first surface to a temperature between the first and the second order phase transition temperatures of the polyethylene, while maintaining the second surface at a temperature above the first order phase transition temperature for a period of time sufficient to form sperulites of crystals adjacent the first surface and then
cooling the whole of the article to room temperture.

### Claim 2 (depends on 1)

The process of claim 1 wherein the polyethylene resin is a high molecular weight-high density polyethylene resin.

### Claim 3 (depends on 1)

The process of claim 1 wherein the heating zone comprises a heating zone in a thermoplastic extruder for extrusion and the shaping zone is the extruder die.

### Claim 4 (depends on 3)

The process of claim 3 wherein the extruder die extrudes a monolayer extrudate.

### Claim 5 (depends on 3)

The process of claim 3 wherein the extruder die extrudes a multi-layer extrudate.

### Claim 6 (depends on 5)

The process of claim 5 wherein the polyethylene resin is extruded as one layer of the multi-layered extrudate.

### Claim 7 (depends on 1)

Articles prepared by the process of claim 1.

### Claim 8 (depends on 7)

Articles of claim 7 which are containers.

### Claim 9 (depends on 1)

The process of claim 1 which further comprises blowing the article to form a container.