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WO2008155758A2 - Biodegradable barrier material - Google Patents

Biodegradable barrier material Download PDF

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Publication number
WO2008155758A2
WO2008155758A2 PCT/IL2008/000800 IL2008000800W WO2008155758A2 WO 2008155758 A2 WO2008155758 A2 WO 2008155758A2 IL 2008000800 W IL2008000800 W IL 2008000800W WO 2008155758 A2 WO2008155758 A2 WO 2008155758A2
Authority
WO
WIPO (PCT)
Prior art keywords
pvoh
raw material
extruder
extruding
inert gas
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/IL2008/000800
Other languages
French (fr)
Other versions
WO2008155758A3 (en
Inventor
Yossie Gissis
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Publication of WO2008155758A2 publication Critical patent/WO2008155758A2/en
Anticipated expiration legal-status Critical
Publication of WO2008155758A3 publication Critical patent/WO2008155758A3/en
Ceased legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • 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
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/285—Feeding the extrusion material to the extruder
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • 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
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/14—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the particular extruding conditions, e.g. in a modified atmosphere or by using vibration
    • B29C48/143—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the particular extruding conditions, e.g. in a modified atmosphere or by using vibration at a location before or in the feed unit, e.g. influencing the material in the hopper
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • 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
    • B29C2791/00—Shaping characteristics in general
    • B29C2791/004—Shaping under special conditions
    • B29C2791/006—Using vacuum
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • 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
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/001—Combinations of extrusion moulding with other shaping operations
    • B29C48/0018—Combinations of extrusion moulding with other shaping operations combined with shaping by orienting, stretching or shrinking, e.g. film blowing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • 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
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/001—Combinations of extrusion moulding with other shaping operations
    • B29C48/0019—Combinations of extrusion moulding with other shaping operations combined with shaping by flattening, folding or bending
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • 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
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
    • B29C48/07—Flat, e.g. panels
    • B29C48/08—Flat, e.g. panels flexible, e.g. films
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • 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
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
    • B29C48/09—Articles with cross-sections having partially or fully enclosed cavities, e.g. pipes or channels
    • B29C48/10—Articles with cross-sections having partially or fully enclosed cavities, e.g. pipes or channels flexible, e.g. blown foils
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • 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
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/285—Feeding the extrusion material to the extruder
    • B29C48/286—Raw material dosing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • 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
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/285—Feeding the extrusion material to the extruder
    • B29C48/295—Feeding the extrusion material to the extruder in gaseous form
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • 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
    • B29K2029/00—Use of polyvinylalcohols, polyvinylethers, polyvinylaldehydes, polyvinylketones or polyvinylketals or derivatives thereof as moulding material
    • B29K2029/04—PVOH, i.e. polyvinyl alcohol
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • 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
    • B29K2995/00—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds
    • B29K2995/0037—Other properties
    • B29K2995/0059—Degradable

Definitions

  • the present invention relates to extrusion of polyvinyl alcohol (PVOH).
  • Polyvinyl alcohol is a known material having desirable biodegradability and high barrier qualities. A difficulty arises in the conventional extrusion of polyvinyl alcohol due to the fact that its melting temperature is lower than the temperature at which it begins to decompose.
  • the present invention seeks to provide a system and methodology for extruding PVOH wherein oxygen is generally prevented from entering into the extruder.
  • PVOH supply with an oxygen-free atmosphere such as an inert gas, for example
  • a vacuum may be maintained at the entrance to the extruder and at the PVOH supply.
  • vacuum and gas flushing either the application of the vacuum or the gas flushing may take place first.
  • a system for extruding PVOH including an extruder and a PVOH raw material feed to the extruder, the PVOH raw material feed to the extruder being maintained generally oxygen free, such that oxygen is generally prevented from entering into the extruder.
  • the PVOH raw material feed includes a raw material pathway that is maintained under vacuum. Additionally or alternatively, the PVOH raw material feed includes a raw material pathway that is maintained generally in an inert gas environment. In accordance with a preferred embodiment of the present invention the raw material pathway includes a vacuum environment portion upstream of an inert gas environment portion. Additionally or alternatively, the raw material pathway includes an inert gas environment portion upstream of a vacuum environment portion.
  • a method for extruding PVOH including supplying PVOH raw material to an extruder in a manner such that oxygen is generally prevented from entering into the extruder and extruding the PVOH raw material into at least one of a strip or a sleeve.
  • the PVOH raw material is supplied to the extruder via a raw material pathway that is maintained under vacuum. Additionally or alternatively, the PVOH raw material is supplied to the extruder via a raw material pathway that is maintained generally in an inert gas environment.
  • the raw material pathway includes a vacuum environment portion upstream of an inert gas environment portion. Additionally or alternatively, the raw material pathway includes an inert gas environment portion upstream of a vacuum environment portion.
  • Figs. IA and IB are simplified pictorial illustrations of extrusion apparatus for extruding strips of PVOH in accordance with two alternative embodiments of the present invention
  • Figs. 2 A and 2B are simplified pictorial illustrations of extrusion apparatus for extruding sleeves of PVOH in accordance with two alternative embodiments of the present invention.
  • Fig. IA is a simplified pictorial illustration of extrusion apparatus for extruding resin of PVOH in accordance with an embodiment of the present invention.
  • PVOH raw material typically in the form of pellets 100, is supplied via a vacuum chamber 102 to a sealed tank 104.
  • the vacuum chamber 102 is maintained under a desired vacuum, typically produced by the operation of a vacuum pump 106.
  • the sealed tank 104 is preferably maintained generally oxygen free, preferably containing no more than 5 - 7% Oxygen, by a circulating supply of an inert gas, such as nitrogen, which may be stored in a tank 108.
  • a raw material supply conduit 110 which is preferably maintained generally oxygen free, preferably containing no more than 5 - 7% Oxygen, supplies the raw material pellets 100 to an extruder 112, which may be a conventional extruder for materials such as PVOH.
  • the extruder preferably heats the PVOH to a desired temperature, typically around 200-245 degrees C and supplies a heated melted ribbon of PVOH 114 to an extrusion die 116, which outputs a strip 118 of PVOH, which is collected on a chill roll 120.
  • Fig. IB is a simplified pictorial illustration of extrusion apparatus for extruding strips of PVOH in accordance with another embodiment of the present invention.
  • PVOH raw material typically in the form of pellets 200
  • a sealed tank 204 As seen in Fig. IB, PVOH raw material, typically in the form of pellets 200, is supplied via an oxygen free chamber 202 to a sealed tank 204.
  • the oxygen-free chamber 202 is preferably maintained generally oxygen free, preferably containing no more than 5 - 7% Oxygen, by a circulating supply of an inert gas, such as nitrogen, which may be stored in a tank 206.
  • Sealed tank 204 is preferably maintained under a desired vacuum, typically produced by the operation of a vacuum pump 208.
  • a raw material supply conduit 210 which is preferably maintained generally oxygen free, preferably containing no more than 5 - 7% Oxygen, supplies the raw material pellets 200 to an extruder 212, which may be a conventional extruder for materials such as PVOH.
  • the extruder preferably heats the PVOH to a desired temperature, typically around 200-245 degrees C, and supplies a heated melted ribbon of PVOH 214 to an extrusion die 216, which outputs a strip 218 of PVOH, which is collected on a chill roll 220.
  • Fig. 2A is a simplified pictorial illustration of extrusion apparatus for extruding sleeves of PVOH in accordance with an embodiment of the present invention.
  • PVOH raw material typically in the form of pellets 300, is supplied via a vacuum chamber 302 to a sealed tank 304.
  • the vacuum chamber 302 is maintained under a desired vacuum, typically produced by the operation of a vacuum pump 306.
  • the sealed tank 304 is preferably maintained generally oxygen free, preferably containing no more than 5 - 7% Oxygen, by a circulating supply of an inert gas, such as nitrogen, which may be stored in a tank 308.
  • a raw material supply conduit 310 which is preferably maintained generally oxygen free, preferably containing no more than 5 - 7% Oxygen, supplies the raw material pellets 300 to an extruder 312, which may be a conventional extruder for materials such as PVOH.
  • the extruder preferably heats the PVOH to a desired temperature, typically 200-245 degrees C, and supplies a heated ribbon of PVOH 314 to an extrusion die 316, which outputs a sleeve 318 of PVOH, which is collected on a chill roll 320.
  • Fig. 2B is a simplified pictorial illustration of extrusion apparatus for extruding sleeves of PVOH in accordance with another embodiment of the present invention.
  • PVOH raw material typically in the form of pellets 400, is supplied via an oxygen free chamber 402 to a sealed tank 404.
  • the oxygen-free chamber 402 is preferably maintained generally oxygen free, preferably containing no more than 5 - 7% Oxygen, by a circulating supply of an inert gas, such as nitrogen, which may be stored in a tank 406.
  • Sealed tank 404 is preferably maintained under a desired vacuum, typically produced by the operation of a vacuum pump 408.
  • a raw material supply conduit 410 which is preferably maintained generally oxygen free, preferably containing no more than 5 - 7% Oxygen, supplies the raw material pellets 400 to an extruder 412, which may be a conventional extruder for materials such as PVOH.
  • the extruder preferably heats the PVOH to a desired temperature, typically 200-245 degrees C, and supplies a heated ribbon of PVOH 414 to an extrusion die 416, which outputs a sleeve 418 of PVOH, which is collected on a chill roll 420.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Extrusion Moulding Of Plastics Or The Like (AREA)

Abstract

A system for extruding PVOH including an extruder and a PVOH raw material feed to the extruder, the PVOH raw material feed to the extruder being maintained generally oxygen free, such that oxygen is generally prevented from entering into the extruder.

Description

BIODEGRADABLE BARRIER MATERIAL
REFERENCE TO RELATED APPLICATIONS
Reference is made to U.S. Provisional Patent Application Serial No. 60/933,711, filed June 20, 2007 and entitled BIODEGRADABLE BARRIER MATERIAL, the disclosure of which is hereby incorporated by reference and priority of which is hereby claimed pursuant to 37 CFR 1.78(a) (4) and (5)(i).
FIELD OF THE INVENTION
The present invention relates to extrusion of polyvinyl alcohol (PVOH).
BACKGROUND OF THE INVENTION
Polyvinyl alcohol (PVOH) is a known material having desirable biodegradability and high barrier qualities. A difficulty arises in the conventional extrusion of polyvinyl alcohol due to the fact that its melting temperature is lower than the temperature at which it begins to decompose.
Proposed solutions to this problem include blending PVOH with various materials in order to enable the blend to be extruded. The following prior art patents are believed to represent the current state of the art: U.S. Patents 5,051,222; 5,369,168; 5,952,433 and 6,020,425. SUMMARY OF THE INVENTION
The present invention seeks to provide a system and methodology for extruding PVOH wherein oxygen is generally prevented from entering into the extruder.
This may be achieved by flushing the interior of the extruder and the
PVOH supply with an oxygen-free atmosphere, such as an inert gas, for example
Nitrogen. Alternatively or additionally, a vacuum may be maintained at the entrance to the extruder and at the PVOH supply. When both vacuum and gas flushing are employed, either the application of the vacuum or the gas flushing may take place first.
There is thus provided in accordance with a preferred embodiment of the present invention a system for extruding PVOH including an extruder and a PVOH raw material feed to the extruder, the PVOH raw material feed to the extruder being maintained generally oxygen free, such that oxygen is generally prevented from entering into the extruder.
Preferably, the PVOH raw material feed includes a raw material pathway that is maintained under vacuum. Additionally or alternatively, the PVOH raw material feed includes a raw material pathway that is maintained generally in an inert gas environment. In accordance with a preferred embodiment of the present invention the raw material pathway includes a vacuum environment portion upstream of an inert gas environment portion. Additionally or alternatively, the raw material pathway includes an inert gas environment portion upstream of a vacuum environment portion.
There is also provided in accordance with another preferred embodiment of the present invention a method for extruding PVOH including supplying PVOH raw material to an extruder in a manner such that oxygen is generally prevented from entering into the extruder and extruding the PVOH raw material into at least one of a strip or a sleeve.
Preferably, the PVOH raw material is supplied to the extruder via a raw material pathway that is maintained under vacuum. Additionally or alternatively, the PVOH raw material is supplied to the extruder via a raw material pathway that is maintained generally in an inert gas environment. In accordance with a preferred embodiment of the present invention the raw material pathway includes a vacuum environment portion upstream of an inert gas environment portion. Additionally or alternatively, the raw material pathway includes an inert gas environment portion upstream of a vacuum environment portion.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be understood and appreciated more fully from the following detailed description, taken in conjunction with the drawings in which:
Figs. IA and IB are simplified pictorial illustrations of extrusion apparatus for extruding strips of PVOH in accordance with two alternative embodiments of the present invention; and Figs. 2 A and 2B are simplified pictorial illustrations of extrusion apparatus for extruding sleeves of PVOH in accordance with two alternative embodiments of the present invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Reference is now made to Fig. IA, which is a simplified pictorial illustration of extrusion apparatus for extruding resin of PVOH in accordance with an embodiment of the present invention. As seen in Fig. IA, PVOH raw material, typically in the form of pellets 100, is supplied via a vacuum chamber 102 to a sealed tank 104.
The vacuum chamber 102 is maintained under a desired vacuum, typically produced by the operation of a vacuum pump 106. The sealed tank 104 is preferably maintained generally oxygen free, preferably containing no more than 5 - 7% Oxygen, by a circulating supply of an inert gas, such as nitrogen, which may be stored in a tank 108. A raw material supply conduit 110, which is preferably maintained generally oxygen free, preferably containing no more than 5 - 7% Oxygen, supplies the raw material pellets 100 to an extruder 112, which may be a conventional extruder for materials such as PVOH. The extruder preferably heats the PVOH to a desired temperature, typically around 200-245 degrees C and supplies a heated melted ribbon of PVOH 114 to an extrusion die 116, which outputs a strip 118 of PVOH, which is collected on a chill roll 120.
Reference is now made to Fig. IB, which is a simplified pictorial illustration of extrusion apparatus for extruding strips of PVOH in accordance with another embodiment of the present invention. As seen in Fig. IB, PVOH raw material, typically in the form of pellets 200, is supplied via an oxygen free chamber 202 to a sealed tank 204.
The oxygen-free chamber 202 is preferably maintained generally oxygen free, preferably containing no more than 5 - 7% Oxygen, by a circulating supply of an inert gas, such as nitrogen, which may be stored in a tank 206. Sealed tank 204 is preferably maintained under a desired vacuum, typically produced by the operation of a vacuum pump 208. A raw material supply conduit 210, which is preferably maintained generally oxygen free, preferably containing no more than 5 - 7% Oxygen, supplies the raw material pellets 200 to an extruder 212, which may be a conventional extruder for materials such as PVOH. The extruder preferably heats the PVOH to a desired temperature, typically around 200-245 degrees C, and supplies a heated melted ribbon of PVOH 214 to an extrusion die 216, which outputs a strip 218 of PVOH, which is collected on a chill roll 220.
Reference is now made to Fig. 2A, which is a simplified pictorial illustration of extrusion apparatus for extruding sleeves of PVOH in accordance with an embodiment of the present invention. As seen in Fig. 2A, PVOH raw material, typically in the form of pellets 300, is supplied via a vacuum chamber 302 to a sealed tank 304.
The vacuum chamber 302 is maintained under a desired vacuum, typically produced by the operation of a vacuum pump 306. The sealed tank 304 is preferably maintained generally oxygen free, preferably containing no more than 5 - 7% Oxygen, by a circulating supply of an inert gas, such as nitrogen, which may be stored in a tank 308. A raw material supply conduit 310, which is preferably maintained generally oxygen free, preferably containing no more than 5 - 7% Oxygen, supplies the raw material pellets 300 to an extruder 312, which may be a conventional extruder for materials such as PVOH. The extruder preferably heats the PVOH to a desired temperature, typically 200-245 degrees C, and supplies a heated ribbon of PVOH 314 to an extrusion die 316, which outputs a sleeve 318 of PVOH, which is collected on a chill roll 320.
Reference is now made to Fig. 2B, which is a simplified pictorial illustration of extrusion apparatus for extruding sleeves of PVOH in accordance with another embodiment of the present invention. As seen in Fig. 2B, PVOH raw material, typically in the form of pellets 400, is supplied via an oxygen free chamber 402 to a sealed tank 404.
The oxygen-free chamber 402 is preferably maintained generally oxygen free, preferably containing no more than 5 - 7% Oxygen, by a circulating supply of an inert gas, such as nitrogen, which may be stored in a tank 406. Sealed tank 404 is preferably maintained under a desired vacuum, typically produced by the operation of a vacuum pump 408. A raw material supply conduit 410, which is preferably maintained generally oxygen free, preferably containing no more than 5 - 7% Oxygen, supplies the raw material pellets 400 to an extruder 412, which may be a conventional extruder for materials such as PVOH. The extruder preferably heats the PVOH to a desired temperature, typically 200-245 degrees C, and supplies a heated ribbon of PVOH 414 to an extrusion die 416, which outputs a sleeve 418 of PVOH, which is collected on a chill roll 420.
It will be appreciated by persons skilled in the art that the present invention is not limited to what has been particularly shown and described hereinabove. Rather the invention includes both combinations and subcombinations of features described hereinabove as well as variations thereof which would be apparent to those reading the aforesaid description and are not in the prior art.

Claims

C L A I M S
1. A system for extruding PVOH comprising: an extruder; and a PVOH raw material feed to said extruder, said PVOH raw material feed to said extruder being maintained generally oxygen free, such that oxygen is generally prevented from entering into the extruder.
2. A system for extruding PVOH according to claim 1 and wherein said PVOH raw material feed comprises a raw material pathway that is maintained under vacuum.
3. A system for extruding PVOH according to claim 1 or claim 2 and wherein said PVOH raw material feed comprises a raw material pathway that is maintained generally in an inert gas environment.
4. A system for extruding PVOH according to any of the preceding claims and wherein said raw material pathway includes a vacuum environment portion upstream of an inert gas environment portion.
5. A system for extruding PVOH according to any of the preceding claims and wherein said raw material pathway includes an inert gas environment portion upstream of a vacuum environment portion.
6. A method for extruding PVOH comprising: supplying PVOH raw material to an extruder in a manner such that oxygen is generally prevented from entering into the extruder; and extruding said PVOH raw material into at least one of a strip or a sleeve.
7. A method for extruding PVOH according to claim 6 and wherein said
PVOH raw material is supplied to said extruder via a raw material pathway that is maintained under vacuum.
8. A method for extruding PVOH according to claim 6 or claim 7 and wherein said PVOH raw material is supplied to said extruder via a raw material pathway that is maintained generally in an inert gas environment.
9. A method for extruding PVOH according to either of the preceding claims 7 and S and wherein said raw material pathway includes a vacuum environment portion upstream of an inert gas environment portion.
10. A method for extruding PVOH according to any of the preceding claims
7 - 9 and wherein said raw material pathway includes an inert gas environment portion upstream of a vacuum environment portion.
PCT/IL2008/000800 2007-06-20 2008-06-12 Biodegradable barrier material Ceased WO2008155758A2 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US93671107P 2007-06-20 2007-06-20
US60/936,711 2007-06-20

Publications (2)

Publication Number Publication Date
WO2008155758A2 true WO2008155758A2 (en) 2008-12-24
WO2008155758A3 WO2008155758A3 (en) 2010-02-25

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/IL2008/000800 Ceased WO2008155758A2 (en) 2007-06-20 2008-06-12 Biodegradable barrier material

Country Status (1)

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Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4392804A (en) * 1981-09-04 1983-07-12 The Continental Group, Inc. Solid stating
US4402900A (en) * 1982-11-01 1983-09-06 E. I. Du Pont De Nemours & Co. Dry spinning process with a gas flow amplifier
DE69818801T2 (en) * 1997-02-13 2004-08-19 E.I. Du Pont De Nemours And Co., Wilmington SPIDER CELL AND DRY SPINNING METHOD OF SPANDEX
DE19854689A1 (en) * 1998-11-26 2000-06-08 Buehler Ag Method and device for processing a thermoplastic polycondensate
DE10140597A1 (en) * 2001-08-18 2003-03-06 Kuraray Specialities Europe Partially cross-linked polyvinyl alcohol

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