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WO2002012379A1 - Procede de preparation de polymeres expanses reticules - Google Patents

Procede de preparation de polymeres expanses reticules Download PDF

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Publication number
WO2002012379A1
WO2002012379A1 PCT/GB2001/003496 GB0103496W WO0212379A1 WO 2002012379 A1 WO2002012379 A1 WO 2002012379A1 GB 0103496 W GB0103496 W GB 0103496W WO 0212379 A1 WO0212379 A1 WO 0212379A1
Authority
WO
WIPO (PCT)
Prior art keywords
temperature
polymer
blowing agent
decomposition
crosslinking
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/GB2001/003496
Other languages
English (en)
Inventor
Neil Witten
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.)
Zotefoams PLC
Original Assignee
Zotefoams PLC
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 Zotefoams PLC filed Critical Zotefoams PLC
Priority to AU2001275761A priority Critical patent/AU2001275761A1/en
Publication of WO2002012379A1 publication Critical patent/WO2002012379A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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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
    • B29C44/00—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles
    • B29C44/02—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles for articles of definite length, i.e. discrete articles
    • B29C44/10—Applying counter-pressure during expanding
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
    • C08J9/04—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent
    • C08J9/06—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent by a chemical blowing agent
    • C08J9/10—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent by a chemical blowing agent developing nitrogen, the blowing agent being a compound containing a nitrogen-to-nitrogen bond
    • C08J9/102—Azo-compounds
    • C08J9/103—Azodicarbonamide

Definitions

  • the present invention relates to a process for the preparation of shaped closed cell, cross-linked polymer foam, apparatus for the preparation thereof, shaped closed cell cross-linked polymer foam obtained therewith and the use thereof. More particularly the invention relates to a process for the preparation of shaped closed cell cross-linked polymer foam incorporating the use of foaming agents, the apparatus for the preparation thereof, polymer foam obtained thereby and their use.
  • polymers such as low density polyethylene (LDPE), linear low density polyethylene (LLDPE), copolymers of ethylene, styrene butadiene copolymers, polyisoprene and others may be expanded to produce foams by the incorporation of and subsequent reaction by heat of chemical blowing agents, an example of which is Azodicarbonamide (ADCN).
  • LDPE low density polyethylene
  • LLDPE linear low density polyethylene
  • ADCN Azodicarbonamide
  • crosslinking step enhances processability by widening the 'foaming' process window and allows a degree of control over cell size in the final product.
  • a typical process for the manufacture of such foams of density down to 70kg/m 3 comprises a 'single stage' expansion process comprising three steps:
  • step b only partial release of expansion gases, through blowing agent decomposition prior to
  • step b decomposition of blowing agent, and cooling to prevent full expansion prior to
  • the process of the invention enables controlled expansion to produce a high quality foam, without the need to use multiple moulds or presses. It is a particular advantage of the invention that controlled expansion is substantially isotropic and serves to reduce in-built stresses, with substantially uniform product properties throughout the product.
  • Reference herein to an autoclave is to any vessel allowing control of pressure and temperature of the contents thereof.
  • the process may be employed for the preparation of any desired forms, and is best suited for the preparation of regular forms such as tiles, sheets and other essentially planar products. Size of preforms is suitably selected by anticipation of the subsequent isotropic expansion.
  • mixing and shaping may be carried out by known techniques, for example with use of a compounding extruder with a profiled thick sheet die, and subsequently cutting to required dimensions; or with use of internal mixers, mills etc., and a light press and mould.
  • preforming is via the extrusion method which allows continuous production, improved mix quality and control of foam sheet thicknesses.
  • the process may be used for the preparation of any foamed polymers which are capable of being processed (melted) below the decomposition temperature of the corresponding blowing agent and which enable additive mixing before foaming and crosslinking. It is an advantage that the initiation of the crosslinking reaction serves to maintain preform shape prior to and during decomposition of the chemical blowing agent, whereby controlled expansion is possible.
  • the process is particularly suited for the preparation of known and novel olef ⁇ nic polymers.
  • Known polymers are selected from low density polyethylene (LDPE), such as elastomeric polyethylene or EPDM and elastomeric or plastomeric metallocene polyethylene, and copolymers thereof such as ethylene vinyl acetate (ENA), ethylene acrylic acid (EAA), ethylene methyl acrylate (EMA) and the like. It is within the scope of this invention that the process is suited for preparing foams from novel olef ⁇ nic polymers and polymer blends which are continuously being developed and made commercially available.
  • LDPE low density polyethylene
  • EPDM elastomeric polyethylene or EPDM and elastomeric or plastomeric metallocene polyethylene
  • EAA ethylene vinyl acetate
  • EAA ethylene acrylic acid
  • EMA ethylene methyl acrylate
  • the process is suited for the preparation of polymers having sufficient melt strength to form and maintain a cellular structure on release of blowing agent and to retain their preform shape at temperatures in excess of or equal to 165°C.
  • Melt strength may be controlled by selection of polymer rheological properties, and/or nature or amount of crosslinking agent Any crosslinking agent may be employed which is compatible with the polymer.
  • Preferred crosslinking agent comprises a high temperature decomposition peroxide. Peroxides commonly employed are those of the diarylalkyl peroxide class, such as dicumyl peroxide or ⁇ . ⁇ - bis(tert- butylperoxy) disopropylbenzene.
  • the crosslinking agent is selected in nature and amount to give sufficient cohesion to provide melt stability during blowing agent decomposition at elevated temperature.
  • blowing agent Any known blowing agent may be employed which is compatible with the selected polymer as powder or master batch (granule preblend) and releases sufficient gas to achieve desired foaming and density reduction.
  • Conventional chemical blowing agents such as azodicarbonamide (ADCN) are preferred for generating gases within the polymer
  • any additional agents may be added such as activator, solvent, heat transfer materials, such as refractory materials and inorganic oxides, lubricant, filler, pigment and the like as known in the art.
  • the inert atmosphere in the autoclave is suitably provided by known means to prevent oxidation and avoid fire hazard, and preferably comprises a nitrogen, argon or like atmosphere.
  • Heating of the polymer formulation in the step (b) may be by any suitable means and is preferably convective heating by heat of gases in the autoclave. Heating is to a temperature in the range 80-250°C, depending on the nature of the polymer, crosslinking agent and blowing agent, sufficient to initiate crosslinking with subsequent decomposition of the chemical blowing agent.
  • the process comprises preparation of a closed cell crosslinked polymer foam according to steps a-c as hereinbefore defined of a polymer having melt temperature in a first range Tm, comprising
  • step a) pre-mixing the polymer with a crosslinking agent having activation temperature in a second range Ta and a chemical blowing agent having decomposition temperature in a third range Tb, wherein temperature ranges are in increasing or overlapping order Tm ⁇ Ta ⁇ Tb;
  • step b) heating of at least one shaped preform at a rate whereby initial polymer melt takes place partially or completely, followed by partial or complete activation of crosslinking agent, followed by partial or complete decomposition of chemical blowing agent.
  • Suitable temperature ramping may be selected as known in the art, for example uniform or otherwise. Rate of temperature increase and final temperature achieve control of concentration and yield of released gases, uniformity and degree of crosslinking and the like. Rate of temperature increase may be determined by those skilled in the art with reference to size of preforms, efficiency of heat uptake in any given autoclave, nature of polymer, crosslinking agent and blowing agent, desired polymer foam density, (and therefore amount of blowing agent), desired degree of crosslinking and the like. Suitable temperature increase is of the order of l°C/minute - 5°C/m ⁇ ute.
  • Pressure in step b) may be ambient or elevated. Elevated pressure may be applied by any known means suitable with use of autoclaves and is preferably by elevating surrounding gas pressure in the sealed autoclave. It is a particular advantage of the invention that pressure control is uniform about and throughout the polymer, during heating.
  • step c) Pressure in step c) is rapidly reduced to atmospheric. It is a further advantage that an autoclave permits a rapid release of pressure with isotropic expansion in simple and effective manner. Suitably elevated pressure in step (b) is applied in the range up to 25 bar. Pressure reduction in step c) may be at any convenient rate, and may be only constrained by the limitations of valve apertures of a given autoclave allowing gas release.
  • an apparatus for the preparation of shaped closed cell crosslinked polymer foam as hereinbefore defined comprising in line a mixer, means for shaping polymer premix into preforms, and an autoclave for subjecting to elevated temperature and pressure, with means for regulation thereof.
  • a closed cell crosslinked polymer foam or precursor thereof obtained with use of the process or apparatus of the invention as hereinbefore defined.
  • Polymer may be of any desired size and form, preferably in the form of tiles or sheets as hereinbefore defined. Final required foam size is restricted only by size constraint of apparatus used.
  • Figure 1 illustrates a conventional apparatus and process
  • FIG. 2 illustrates the apparatus and process of the invention.
  • Figure 3 illustrates a suitable temperature/time profile for step b) of the invention.
  • the apparatus comprises means for mixing and shaping polymer and sets of moulds contained polymer for processing. It will be appreciated that the additional work required in the two stage process for transferring polymer from a mould to a second mould or to an oven is cumbersome and requires additional manpower or automation.
  • Figure 2 is illustrated a premixing and extrusion apparatus, in line with an autoclave.
  • the use of moulds is not required and preformed polymer is simply stacked onto shelves for processing. Processing is rapid allowing efficient batchwise production of high quality polymer foam.
  • a formulation consisting of polymer granules, crosslinking agent and 5 chemical blowing agent were blended and fed continuously to an extrusion hopper in the following proportions:
  • the materials were mixed at temperature in the range 110°C to 125°C to form 0 a melt which was extruded at a controlled output rate to produce a homogeneous, continuous sheet.
  • the sheet was allowed to self-cool due to the low linear speed giving an evenly crystallised sheet product and so minimising internal stress.
  • the cooled sheet was sectioned into pre-defined blocks and subsequently stacked onto supporting shelves of an autoclave. 5
  • the autoclave operates batch-wise and can contain any number of sheets, being constrained only by the size and design of the vessel. In this example twenty-one sheets were simultaneously expanded into foam.
  • the vessel was evacuated and filled with nitrogen gas.
  • the gas pressure was then increased from atmospheric to 20 bar at a rate of 19 bar per minute, i.e. for one minute.
  • the temperature of the gas within the autoclave was increased at a rate of 3°C per minute up to 200°C.
  • the gas pressure was released rapidly, subject only to the constraints of the apparatus. On full pressure release the foamed blocks were removed from the autoclave and allowed to cool at ambient temperature and pressure.

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  • Chemical & Material Sciences (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)

Abstract

L'invention porte sur un procédé de préparation de polymères expansés réticulées àcellules fermées par expansion en une seule phase consistant: (a) à prémélanger le polymère, un agent réticulant et un agent chimique gonflant à une température non suffisante pour activer la réticulation, et la décomposition de l'agent gonflant; (b) à placer au moins une préforme de forme et dimensions voulues du prémélange (a) dans un autoclave sous atmosphère inerte et à température élevée pour amorcer à la fois la réticulation, et la décomposition de l'agent gonflant, et (c) puis à soumettre l'ensemble à une dépression rapide suffisante pour permettre une expansion complète par les gaz d'expansion libérés en (b). L'invention porte également sur un appareil à cet effet, sur le polymère expansé ainsi obtenu et sur ses utilisations.
PCT/GB2001/003496 2000-08-05 2001-08-02 Procede de preparation de polymeres expanses reticules Ceased WO2002012379A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU2001275761A AU2001275761A1 (en) 2000-08-05 2001-08-02 Process for the preparation of cross linked polymer foam

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0019171.8 2000-08-05
GB0019171A GB0019171D0 (en) 2000-08-05 2000-08-05 Process for the preparation of cross linked expanded polymer film

Publications (1)

Publication Number Publication Date
WO2002012379A1 true WO2002012379A1 (fr) 2002-02-14

Family

ID=9896988

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB2001/003496 Ceased WO2002012379A1 (fr) 2000-08-05 2001-08-02 Procede de preparation de polymeres expanses reticules

Country Status (3)

Country Link
AU (1) AU2001275761A1 (fr)
GB (1) GB0019171D0 (fr)
WO (1) WO2002012379A1 (fr)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7059475B2 (en) 2001-10-04 2006-06-13 Entegris, Inc. System for cushioning wafer in wafer carrier
US7291382B2 (en) 2004-09-24 2007-11-06 Kimberly-Clark Worldwide, Inc. Low density flexible resilient absorbent open-cell thermoplastic foam
US7358282B2 (en) 2003-12-05 2008-04-15 Kimberly-Clark Worldwide, Inc. Low-density, open-cell, soft, flexible, thermoplastic, absorbent foam and method of making foam
WO2009063187A1 (fr) * 2007-11-12 2009-05-22 Zotefoams Plc Mousses de polymère fluoré préparées à l'aide d'agents gonflants et leurs applications
WO2010149441A1 (fr) * 2009-06-26 2010-12-29 Evonik Röhm Gmbh Procédé de fabrication d'une pièce en mousse à partir de poly(méth)acrylates réticulés ainsi que ladite mousse et ses utilisations
US8158689B2 (en) 2005-12-22 2012-04-17 Kimberly-Clark Worldwide, Inc. Hybrid absorbent foam and articles containing it
US8852473B1 (en) * 2008-09-23 2014-10-07 Wright Materials Research Co. Reinforced polymer composite foams and method of manufacture
US10392488B2 (en) 2013-10-11 2019-08-27 Basf Se Method for producing expanded thermoplastic elastomer particles
US12495861B2 (en) 2022-10-21 2025-12-16 Under Armour, Inc. Sole structure for an article of footwear having enhanced roll acceleration

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS56111658A (en) * 1980-02-08 1981-09-03 Toyo Rubber Chem Ind Co Ltd Preparation of low density rubber foamy body
US4559190A (en) * 1983-10-14 1985-12-17 Agip Petroli S.P.A. Process for the production of expanded reticulated polyethylene

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS56111658A (en) * 1980-02-08 1981-09-03 Toyo Rubber Chem Ind Co Ltd Preparation of low density rubber foamy body
US4559190A (en) * 1983-10-14 1985-12-17 Agip Petroli S.P.A. Process for the production of expanded reticulated polyethylene

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
DATABASE WPI Section Ch Week 198142, Derwent World Patents Index; Class A32, AN 1981-76667D, XP002182217 *

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7059475B2 (en) 2001-10-04 2006-06-13 Entegris, Inc. System for cushioning wafer in wafer carrier
US7358282B2 (en) 2003-12-05 2008-04-15 Kimberly-Clark Worldwide, Inc. Low-density, open-cell, soft, flexible, thermoplastic, absorbent foam and method of making foam
US7291382B2 (en) 2004-09-24 2007-11-06 Kimberly-Clark Worldwide, Inc. Low density flexible resilient absorbent open-cell thermoplastic foam
US8158689B2 (en) 2005-12-22 2012-04-17 Kimberly-Clark Worldwide, Inc. Hybrid absorbent foam and articles containing it
WO2009063187A1 (fr) * 2007-11-12 2009-05-22 Zotefoams Plc Mousses de polymère fluoré préparées à l'aide d'agents gonflants et leurs applications
US8227521B2 (en) 2007-11-12 2012-07-24 Zotefoams Plc Fluoropolymer foams prepared with the use of blowing agents and applications thereof
US8852473B1 (en) * 2008-09-23 2014-10-07 Wright Materials Research Co. Reinforced polymer composite foams and method of manufacture
WO2010149441A1 (fr) * 2009-06-26 2010-12-29 Evonik Röhm Gmbh Procédé de fabrication d'une pièce en mousse à partir de poly(méth)acrylates réticulés ainsi que ladite mousse et ses utilisations
US10392488B2 (en) 2013-10-11 2019-08-27 Basf Se Method for producing expanded thermoplastic elastomer particles
US12495861B2 (en) 2022-10-21 2025-12-16 Under Armour, Inc. Sole structure for an article of footwear having enhanced roll acceleration

Also Published As

Publication number Publication date
GB0019171D0 (en) 2000-09-27
AU2001275761A1 (en) 2002-02-18

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