# US 4,391,939 A · Polymer film treatment with organic impregnant

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- Number: US 4,391,939 A
- Document ID: US4391939A
- Status: Granted
- Kind: A
- Application number: 06/255,029
- Filed: 1981-04-17
- Granted: 1983-07-05
- Earliest claimed: 1981-04-17
- Assignees: Mobil Oil Corporation
- Inventors: Gordon P. Hungerford
- Web page: https://patentgrep.com/patent/US4391939A

## CPC

- C08J 3/18: Plasticising macromolecular compounds (plasticisers C08K)
- C08J 2333/20: Homopolymers or copolymers of acrylonitrile (C08J2355/02 takes precedence)
- 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)

## Abstract

Acrylonitrile polymer film is treated with non-volatile water-miscible glycol plasticizer to improve toughness and other film properties. In a unique, continuous, steady state process polyacrylonitrile aquagel strip is treated with plasticizer additive in concentrated aqueous solution. Aquagel strip is passed at substantially constant rate through a solution treatment bath. The aquagel strip, which may contain at least about 40 weight % water uniformly dispersed in the polyacrylonitrile, is contacted with the aqueous solution during a predetermined residence time in the bath. After passing the treated aquagel strip from the bath, excess aqueous additive solution is removed. The plasticizer additive can be metered to the aqueous solution at concentration greater than the aqueous additive solution of the bath at a rate substantially proportionate to desired steady state uptake of additive for the aquagel strip. By impregnating the film with a low molecular weight glycol, such as triethylene glycol, in-line plasticizer addition is achieved. Novel glycol-plasticized acrylonitrile polymers and packaging films are made.

## Claims

### Claim 1

A self-supporting uniform film consisting essentially of
(a) biaxially-oriented high nitrile addition polymer containing at least 80% acrylonitrile repeating units; and
(b) dispersed in the polymer triethylene glycol in sufficient amount to plasticize the polymer and substantially increase film toughness.

### Claim 2 (depends on 1)

The film of claim 1 wherein the triethylene glycol is present in the amount of at least about 4 weight percent of the polymer.

### Claim 3 (depends on 2)

The film of claim 2 wherein triethylene glycol is present in about 8 to 12 weight percent.

### Claim 4

A continuous steady state process for treating polyacrylonitrile aquagel strip with a nonvolatile low molecular weight polyalkylene glycol having total miscibility with water comprising the steps of:
passing the aquagel strip at substantially constant rate through an aqueous bath of said polyalkylene glycol, said aquagel containing at least about 40 weight % water uniformly dispersed in the polyacrylonitrile;
contacting the aquagel strip with the aqueous bath during a predetermined residence time in the bath;
passing the aquagel strip from the bath while removing excess aqueous bath therefrom;
metering the polyalkylene glycol to the bath at a concentration greater than the aqueous polyalkylene glycol solution of the bath at a rate substantially proportionate to desired steady state treatment of polyalkylene glycol for the aquagel strip.

### Claim 5 (depends on 4)

The process of claim 4 wherein the aquagel strip is machine direction oriented before it is treated with said polyalkylene glycol and tranversely oriented after said treatment.

### Claim 6 (depends on 4)

The process of claim 4 wherein said glycol is triethylene glycol and is metered to the bath in an amount equivalent to at least 4 weight percent based on the dry polymer.

### Claim 7 (depends on 4)

The process of claim 4 wherein the glycol additive is metered to the bath as substantially undiluted liquid and no additional water is input to the process.

### Claim 8

In the process of producing oriented acrylonitrile polymer film by forming a polymer film from a hot solution of polymer in water soluble solvent, washing the polymer film to replace the solvent with water to form an aquagel film, stretching the aquagel to orient the polymer and drying the oriented polymer film to remove water; the improvement which comprises:
treating the aquagel film with sufficient water-miscible glycol to increase impact strength of the polymer.

### Claim 9 (depends on 8)

The process of claim 8 wherein the acrylonitrile polymer contains at least 80 percent acrylonitrile repeating units and the glycol consists essentially of triethylene glycol.