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Film containing alpha-olefin/vinyl aromatic copolymer

a technology of aromatic copolymer and olefin, which is applied in the direction of packaging, synthetic resin layered products, fastening means, etc., can solve the problems of low polymerization activity of such ziegler-natta catalysts, poor control of the polymer chain architecture both within the sequence of a single chain, and differences in catalyst efficiency to achieve polymers of low molecular weight at some sites, and achieve high toughness. , the effect of resistance to punctur

Inactive Publication Date: 2002-05-14
CRYOVAC INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

It has been discovered that olefin / vinyl aromatic copolymers provide stiffer amorphous regions, and therefore can be used to produce films having a high level of toughness, i.e., more resistant to puncture than, for example, ethylene / alpha-olefin copolymers. The stiffer amorphous regions provide advantages in films as applied force is dispersed more evenly, another reason films from such copolymers are tougher.
Olefin / vinyl aromatic copolymers can also be used in the preparation of foams, especially foam sheet, having improved thermoforming characteristics, especially in having improved resistance to cracking. The olefin / vinyl aromatic copolymer can be used to provide a polystyrene barrier tray, such as a barrier foam tray, with improved delamination resistance and structural integrity.

Problems solved by technology

However, for an vinyl aromatic comonomer such as styrene the polymerization activity for such Ziegler-Natta catalysts is low, such that an ethylene / styrene copolymer has a maximum of only about 1 mole percent styrene units in the copolymer.
The result of such multi-site chemistry is a product with poor control of the polymer chain architecture both within the sequence of a single chain, as well as when compared to a neighboring chain.
In addition, differences in catalyst efficiency produce polymers of high molecular weight at some sites and low molecular weight at others.
These polymers have only up to 50 mole percent of the aromatic vinyl polymerization units, because the active site of the catalyst becomes crowded with the incorporation. of the sterically hindered aromatic vinyl comonomer, making it unlikely, or impossible, that another hindered comonomer could enter into the polymerization as the next monomer in the sequence.
Crystallinity generally remains at or about 0%; but, the glass transition temperature rises with an increase in amount of styrene sequences resulting in an increase in stiffness in resultant end products.

Method used

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  • Film containing alpha-olefin/vinyl aromatic copolymer
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  • Film containing alpha-olefin/vinyl aromatic copolymer

Examples

Experimental program
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Effect test

example 1

Preparation of Ethylene / Styrene Copolymer, and Monolayer Film of Ethylene / Styrene Copolymer

Approximately 1 gram of a polymer sample which was determined by GPC, nmr, and DSC analyses to be a blend of at least 90 weight percent of a high molecular weight, thermoplastic, homogeneous, random copolymer having about 80 mole percent ethylene / 20 mole percent styrene (hereinafter "ES Copolymer #1), the balance being polyethylene homopolymer, was placed between separated, horizontally-positioned MYLAR (TM) sheets of a press assembly (comprising a Carver Laboratory Press and stainless steel supporting plates), the resin powder being placed in the center of a lower MYLAR (TM) sheet, which was positioned above a lower stainless steel plate. Thereafter, an upper MYLAR (TM) sheet was placed over and in contact with the powder, after which an upper stainless steel plate was placed over the upper MYLAR (TM) sheet, resulting in an assembly containing the resin powder. After placing this assembly in ...

example 2

Orientation of Monolayer Film of Example 1

The platen of Example 1 was oriented on a T. M. Long Stretcher laboratory orientation unit. The orientation conditions were as follows: air temperature=85.degree. C.; dwell time=30 sec.; stretch ratio=4.times.4; strain rate: 1000 percent per second; plate temperature=85.degree. C. The final oriented monolayer film was recovered from the orientation unit.

example 3

Hot Air Orientation of Multilayer Film Containing Propylene / Ethylene Copolymer and Ethylene / Styrene Copolymer

A palindromic three-layer coextruded film having an A / B / A structure is oriented out of hot air at 115.degree. C. The outer "A" layers are a propylene / ethylene copolymer having 3% by weight of ethylene. The inner "B" layer is an ethylene / styrene copolymer having 2% by mole of styrene (hereinafter "ES Copolymer #2"). The relative thickness of the A / B / A layers is 25 percent / 50 percent / 25 percent, respectively.

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Abstract

Film and sheet materials, and articles made therefrom, such as bags, pouches, trays, etc., comprise one or more layers of a thermoplastic, homogeneous alpha-olefin / vinyl aromatic copolymer, preferably an ethylene / styrene copolymer. The alpha-olefin / vinyl aromatic copolymer has properties which can can provide a desired performance characteristics such as impact resistance, printability, RF sealability, free shrink, optics, as well as many others. The homogeneous alpha-olefin-vinyl aromatic copolymer may be present in a mono-layer film, either alone or in a blend, or may be included in one or more layers of a multilayer film. Also included is a multilayer thermoformable article comprising a web having a film of such alpha-olefin / vinyl aromatic copolymers thereto. Finally, also included is an RF-sealable film comprising such copolymers.

Description

FIELD OF THE INVENTIONThe present invention relates to films comprising olefin / vinyl aromatic copolymer. The present invention relates especially to multilayer films containing ethylene / styrene copolymer.BACKGROUND OF THE INVENTIONThe copolymerization of ethylene and styrene by a conventional Ziegler-Natta catalyst is reported in Polymer Bulletin, 20, p. 237 (1988). Ziegler-Natta catalytic methods are commonly used throughout the polymer industry, especially for the production of ethylene copolymers, and have a long history tracing back to about 1957. However, for an vinyl aromatic comonomer such as styrene the polymerization activity for such Ziegler-Natta catalysts is low, such that an ethylene / styrene copolymer has a maximum of only about 1 mole percent styrene units in the copolymer. Furthermore, because of the heterogeneity of conventional Ziegler-Natta catalysts, the reported copolymer is actually a mixture of polymer chains of varying length, some having more than 1% by mole ...

Claims

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Application Information

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IPC IPC(8): B32B27/32C08F210/02C08F210/00C08F210/16B32B27/08C08J5/18C08L23/06C08L23/08C08L23/14
CPCB32B27/08C08J5/18C08L23/0823C08L23/0853B32B27/32Y10T428/1328C08F210/02C08F210/16C08J2323/08C08L23/06Y10T428/1379Y10T428/1341Y10T428/2826Y10T428/1334Y10T428/1383C08L2666/06C08F212/08C08F2500/26C08F2500/03C08F210/08C08F210/14Y10T428/31913Y10T428/31725Y10T428/3192Y10T428/31928Y10T428/3175B32B2553/00B32B27/065B32B2367/00B32B2323/00B32B2325/00B32B2439/06B32B2250/24B32B5/18B32B2307/7244B32B2250/40B32B27/302B32B27/304B32B27/306B32B2377/00B32B27/36B32B27/34B32B2327/06B32B2329/04B32B2307/736
Inventor BRADFUTE, JOHN G.CHILDRESS, BLAINE CLEMONSHAVENS, MARVINLULHAM, CEDRIC MICHAELMOFFITT, RONALD D.NELSON, MARTINDALENORPOTH, LAWRENCE R.ROBERTS, WILLIAM PEYTONTONEY, GLORIA GARCIAWOFFORD, GEORGE DEAN
Owner CRYOVAC INC