# US 2013/0157031 A1 · Method for Forming a Thermoplastic Composition that Contains a Plasticized Starch Polymer

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- Number: US 2013/0157031 A1
- Document ID: US20130157031A1
- Status: Published application
- Kind: A1
- Application number: 13/330,789
- Filed: 2011-12-20
- Published: 2013-06-20
- Earliest claimed: 2011-12-20
- Assignees: Kimberly-Clark Worlwide, Inc.
- Inventors: James H. Wang; Gregory J. Wideman; JaeHong Lee
- Web page: https://patentgrep.com/patent/US20130157031A1

## CPC

- B29C 48/022: {characterised by the choice of material}
- B29B 7/42: with screw or helix
- B29B 7/726: {Measuring properties of mixture, e.g. temperature or density (B29B7/724 takes precedence)}
- B29B 7/90: Fillers or reinforcements {, e.g. fibres}
- B29B 7/92: Wood chips or wood fibres
- B29B 7/94: Liquid charges
- B29B 9/06: in the form of filamentary material, e.g. combined with extrusion
- B29B 9/12: characterised by structure or composition
- B29C 48/04: Particle-shaped (making granules B29B9/00)
- B29C 48/05: Filamentary, e.g. strands
- B29C 48/08: flexible, e.g. films
- B29C 48/91: Heating, e.g. for cross linking
- B29C 48/911: {Cooling}
- B29C 48/914: {Cooling drums}
- B29B 7/46: with more than one shaft
- B29B 7/728: {Measuring data of the driving system, e.g. torque, speed, power, vibration (B29B7/724 takes precedence)}
- B29B 9/02: by dividing preformed material
- B29B 9/16: Auxiliary treatment of granules
- B29C 48/0022: {combined with cutting}
- B29C 48/345: Extrusion nozzles comprising two or more adjacently arranged ports, for simultaneously extruding multiple strands, e.g. for pelletising
- B29C 48/355: Conveyors for extruded articles
- B29C 48/9135: {of flat articles, e.g. using specially adapted supporting means}
- B29C 48/919: {using a bath, e.g. extruding into an open bath to coagulate or cool the material}
- B29C 2793/009: after shaping
- B29C 2948/92704: Temperature
- B29C 2948/92723: Content, e.g. percentage of humidity, volatiles, contaminants or degassing
- B29C 2948/92923: Calibration, after-treatment or cooling zone
- B29C 2948/92933: Conveying, transporting or storage of articles
- B29C 2948/92942: Moulded article
- B29K 2003/00: Use of starch or derivatives as moulding material
- B29K 2105/0038: {Plasticisers}
- B29K 2995/0056: Biocompatible, e.g. biopolymers or bioelastomers
- B29K 2995/006: Bio-degradable, e.g. bioabsorbable, bioresorbable or bioerodible
- 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)
- B29B: PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
- 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 method and system for melt processing a thermoplastic composition that contains a starch and plasticizer is provided. The composition is melt blended and extruded through a die to form an extrudate, which is thereafter cooled using a multi-stage system of the present invention that includes at least one water-cooling stage and at least one air-cooling stage. More particularly, the extrudate is initially contacted with water for a certain period time so that it becomes partially cooled and solidified on its surface. After the water-cooling stage(s), the extrudate is also subjected to at least one air-cooling stage in which a stream of air is placed into contact with the extrudate.

## Claims

### Claim 1

A method for forming a thermoplastic starch-based composition, the method comprising:
melt extruding a thermoplastic composition through a die to form an extrudate, wherein the thermoplastic composition comprises a starch polymer and plasticizer;
subjecting the extrudate to at least one water-cooling stage in which the extrudate is contacted with water for a first period of time; and
thereafter, subjecting the water-cooled extrudate to at least one air-cooling state in which the extrudate is contacted with air for a second period of time, wherein the air-cooled extrudate has a moisture content of from about 500 to about 20,000 parts per million.

### Claim 2 (depends on 1)

The method of claim 1, wherein the first period of time is from about 1 to about 50 seconds.

### Claim 3 (depends on 1)

The method of claim 1, wherein the temperature of the water is from about 10° C. to about 60° C.

### Claim 4 (depends on 1)

The method of claim 1, wherein the substrate is immersed within a water cooling device during the water-cooling stage.

### Claim 5 (depends on 1)

The method of claim 1, wherein the moisture content of the water-cooled extrudate is from about 2,000 to about 50,000 parts per million.

### Claim 6 (depends on 1)

The method of claim 1, wherein the second period of time is from about 1 to about 50 seconds.

### Claim 7 (depends on 1)

The method of claim 1, wherein the temperature of the stream of air is from about 0° C. to about 40° C.

### Claim 8 (depends on 1)

The method of claim 1, wherein the stream of air is provided by an air knife.

### Claim 9 (depends on 1)

The method of claim 1, wherein the moisture content of the air-cooled extrudate is from 1,000 to about 10,000 parts per million.

### Claim 10 (depends on 1)

The method of claim 1, further comprising pelletizing the air-cooled extrudate.

### Claim 11 (depends on 1)

The method of claim 1, wherein the starch polymer is a corn starch.

### Claim 12 (depends on 1)

The method of claim 1, wherein the plasticizer is a polyhydric alcohol or a sugar alcohol.

### Claim 13 (depends on 1)

The method of claim 1, wherein the weight ratio of starch polymers to plasticizers in the thermoplastic composition is from about 1 to about 10.

### Claim 14 (depends on 1)

The method of claim 1, further comprising melt-extruding the air-cooled extrudate onto a surface to form a substrate.

### Claim 15 (depends on 1)

A film formed according to the method of claim 1, wherein the film has a thickness of about 50 micrometers or less.

### Claim 16 (depends on 17)

The film of claim 17, wherein the film exhibits a percent strain at break of the film in the cross-machine direction of about 550% or more.

### Claim 17 (depends on 17)

The film of claim 17, wherein the film exhibits a modulus of elasticity in the cross-machine direction of from about 80 to about 250 Megapascals.

### Claim 18

A system for forming a thermoplastic starch-based composition, the system comprising:
a supply of a starch polymer and a plasticizer;
an extruder and a die, wherein the starch polymer and plasticizer are capable of being melt blended within the extruder and through the die to form an extrudate;
at least one water-cooling stage located downstream from the extruder and die, the water-cooling stage comprising a water bath within which the extrudate is immersed upon exiting the die; and
at least one air-cooling stage located downstream from the water-cooling stage that is configured to supply a stream of air into contact with the extrudate upon exiting the water bath.

### Claim 19

A method for forming a thermoplastic starch-based composition, the method comprising:
melt extruding a thermoplastic composition through a die to form an extrudate, wherein the thermoplastic composition comprises a starch polymer, plasticizer, biodegradable polymer, polyolefin, and a compatibilizer;
subjecting the extrudate to at least one water-cooling stage in which the extrudate is contacted with water for a first period of time; and
thereafter, subjecting the water-cooled extrudate to at least one air-cooling state in which the extrudate is contacted with air for a second period of time, wherein the air-cooled extrudate has a moisture content of from about 500 to about 20,000 parts per million.

### Claim 20 (depends on 19)

The method of claim 19, wherein the polyolefin is a copolymer of an ethylene and an α-olefin, and the biodegradable polymer is an aliphatic-aromatic copolyester.

### Claim 21 (depends on 20)

The method of claim 20, wherein the compatibilizer has a polar component and a non-polar component, the non-polar component being provided by an olefin.