EP0751859A1 - Thermoformage d'une feuille mince de polystyrene expanse - Google Patents

Thermoformage d'une feuille mince de polystyrene expanse

Info

Publication number
EP0751859A1
EP0751859A1 EP95910905A EP95910905A EP0751859A1 EP 0751859 A1 EP0751859 A1 EP 0751859A1 EP 95910905 A EP95910905 A EP 95910905A EP 95910905 A EP95910905 A EP 95910905A EP 0751859 A1 EP0751859 A1 EP 0751859A1
Authority
EP
European Patent Office
Prior art keywords
webs
sheet
thermoformed
foam
thermoforming
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.)
Withdrawn
Application number
EP95910905A
Other languages
German (de)
English (en)
Inventor
Gary C. Welsh
Marcel Dartee
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.)
Dow Chemical Co
Original Assignee
Dow Chemical Co
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 Dow Chemical Co filed Critical Dow Chemical Co
Publication of EP0751859A1 publication Critical patent/EP0751859A1/fr
Withdrawn legal-status Critical Current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
    • B29C51/00—Shaping by thermoforming, i.e. shaping sheets or sheet like preforms after heating, e.g. shaping sheets in matched moulds or by deep-drawing; Apparatus therefor
    • B29C51/14—Shaping by thermoforming, i.e. shaping sheets or sheet like preforms after heating, e.g. shaping sheets in matched moulds or by deep-drawing; Apparatus therefor using multilayered preforms or sheets
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B37/00—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding
    • B32B37/04—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by the partial melting of at least one layer
    • 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
    • B29C51/00—Shaping by thermoforming, i.e. shaping sheets or sheet like preforms after heating, e.g. shaping sheets in matched moulds or by deep-drawing; Apparatus therefor
    • B29C51/02—Combined thermoforming and manufacture of the preform
    • 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
    • C08J9/22—After-treatment of expandable particles; Forming foamed products
    • 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
    • B29C2793/00—Shaping techniques involving a cutting or machining operation
    • B29C2793/009—Shaping techniques involving a cutting or machining operation after shaping
    • 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
    • B29C51/00—Shaping by thermoforming, i.e. shaping sheets or sheet like preforms after heating, e.g. shaping sheets in matched moulds or by deep-drawing; Apparatus therefor
    • B29C51/08—Deep drawing or matched-mould forming, i.e. using mechanical means only
    • B29C51/082—Deep drawing or matched-mould forming, i.e. using mechanical means only by shaping between complementary mould parts
    • 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
    • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
    • B29K2105/04—Condition, form or state of moulded material or of the material to be shaped cellular or porous
    • B29K2105/043—Skinned foam

Definitions

  • This invention relates to a process for providing improved thermoformed parts made from thin polystyrene foam sheet prepared with a blowing agent which preferably comprises only or predominately carbon dioxide (C0 2) .
  • the invention is particularly suited for making such polystyrene foam sheet having a thickness of less than about 1/2 inch (12.7mm) which is to be thermoformed into products like containers such as trays, cups, tubs and the like. It has become increasingly important to provide polystyrene foam sheet with blowing agents other than halogenated or aliphatic hydrocarbons for environmental reasons and to be in compliance with regulations.
  • One solution is to produce such foam using a blowing agent which is comprised essentially of carbon dioxide as described in U.S. Patent 5,250,577 of which one of the i nventors hereof is the i nventor.
  • gauge variation is sometimes referred to as corrugations which not only adversely affects cell size, surface characteristics, and overall tray functionality measured in terms of brittleness and corresponding container overwrapability, but final part aesthetics as well. It is therefore desirable to manufacture high gauge, low density thermoformed polystyrene foam sheet products which have preferred cell size, adequate surface characteristics and physical performance.
  • This invention takes advantage of the easier processing window associated with lower gauge C0 blown polystyrene foam sheet to manufacture a superior high gauge low density thermoformed polystyrene foam sheet product with better physical and aesthetic characteristics than heretofore possible. As the gauge levels increase the difficulty in extruding increases.
  • the present invention takes advantage of the fact that it is easier to extrude a lower gauge product with minimal gauge variation and smaller cell size The improved result is achieved by extruding two or more webs of lower gauge than the finai desired gauge and joining these thinner webs into a single sheet of desired gauge prior to thermoformmg.
  • thermoforming provides a slight compression and ordinariiy sufficient heat to the foam webs to not only permit the web sheet formed from the material to be thermoformable in a conventional manner but also to obtain good adhesion between the adjoining component web inside surfaces.
  • the process concludes by the thermoformed parts being trimmed from the sheet in a conventional manner.
  • Figure 1 is a schematic representation of a thermoforming process for forming products in accordance with the present invention
  • Figure 2 is an exploded broken away section of the process of Figure 1 , indicated as section 2-2 thereof, showing multiple webs being brought together for forming into sheet during the thermoforming process.
  • the webs 14 and 16 are made of polystyrene resin foamed with C0 as essentially the sole blowing agent. While webs 14 and 16 have been pre-extruded and inventoried as rolls 10 and 12, it is conceivable that in a fully continuous process webs 14 and 16 could instead be directly extruded from two extruders. Whether sourced from rolls 10 and 12 or directly from extruders, the webs 14 and 16 thereafter meet but are not necessarily joined at a junction 18.
  • an inside surface heater 20 may be employed if a high degree of adhesion between the webs is desired. However the use of an inside surface heater 20 is optional in that it has been discovered that sufficient heat and pressure may be obtained in the thermoforming process itself to provide adequate heat substantially to achieve mutual adhesion of the webs in the final product.
  • Idle rollers 22 help bring the webs 14 and 16 generally together at juncture 18, their respective interfaces 26 and 28 being in close proximity to form the elements of sheet 24.
  • the webs forming sheet 24 thereafter pass through a conventional thermoformer heat tunnel 30 comprised of heating elements 32 and 34 with chain rails 36 and pin chains 38 (like bicycle chains with protruding pins) gripping edges of sheet 24 to move the sheet 24 to a forming station 40.
  • Forming station 40 is comprised of conventional thermoforming match molds 42 and 44 having a male plug 46 and a female cavity 48 of a configuration conforming to a container part desired to be formed.
  • thermoforming station simultaneously provides the dual function of causing web adhesion and shaping in this process as illustrated.
  • molds 42 and 44 close in a conventional way and engage sheet 24
  • a container of the desired configuration is formed in the sheet as illustrated at section 50 of the sheet.
  • Sheet 24 then advances to a conventional trim station 52 including trimming knives 54 on mold part 56 and receptacles 58 in matching mold 60 adapted to receive the trim knives 54 to trim the desired part 62 from the sheet to form a finished part 62.
  • a plurality of finished parts 62 are thereafter discharged and may be stacked at stacking station 64 or removed in any conventional manner well known in the art.
  • the process of forming a single sheet from multiple thinner webs is hereinafter referred to as "co-thermoforming" or “co-thermoformed” sheet by the process of co- thermoforming.
  • co-thermoforming or "co-thermoformed” sheet by the process of co- thermoforming.
  • the current invention takes advantage of the fact that a lower gauge product at a Iow density with minimal gauge variation is more readily extrudable than is the same density product at higher gauge, when extruding polystyrene
  • the sheet 24 was then pulled forward through the thermoformer heat tunnel 40 where the outside surfaces of web 24 were heated
  • the sheet 24 comprised of the webs 14 and 16 was then indexed to forming station 52 where the matched molds closed to a specified mold gap to form parts 62 which can be trays having defined walls.
  • This slight 5 compression of the heated foam sheet caused the webs forming sheet 24 to not only be formed but to also provide excellent adhesion between the two i nside surfaces 26 and 28 of webs 14 and 16, respectively, forming sheet 24.
  • the final thermoformed parts were then trimmed from the sheet 24 at trimming station 52 in a conventional manner.
  • thermoforming of polystyrene foam sheet where C0 is the 5 primary or sole blowing agent it is conceivable that this invention would also provide advantages with other resin materials and biowmg agents
  • the resulting products can be containers such as for food products ana the like, but may nave applicaDiiity to pro ⁇ ucts other than containers.

Abstract

L'invention concerne un procédé de co-thermoformage permettant la fabrication de minces feuilles de thermoplastique expansé de faible densité et à cellules de petites dimensions. La feuille mince est constituée de plusieurs bandes en polystyrène de faible épaisseur, ce qui permet de mieux maîtriser la taille des cellules et d'améliorer la fonctionnalité des articles thermoformés à partir de ladite feuille. L'adhérence des feuilles est obtenue au cours du processus de thermoformage. Les produits obtenus par ce procédé de co-thermoformage présentent une ductilité et des caractéristiques de surface améliorées.
EP95910905A 1994-03-24 1995-02-02 Thermoformage d'une feuille mince de polystyrene expanse Withdrawn EP0751859A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US21726294A 1994-03-24 1994-03-24
US217262 1994-03-24
PCT/US1995/001340 WO1995025625A1 (fr) 1994-03-24 1995-02-02 Thermoformage d'une feuille mince de polystyrene expanse

Publications (1)

Publication Number Publication Date
EP0751859A1 true EP0751859A1 (fr) 1997-01-08

Family

ID=22810314

Family Applications (1)

Application Number Title Priority Date Filing Date
EP95910905A Withdrawn EP0751859A1 (fr) 1994-03-24 1995-02-02 Thermoformage d'une feuille mince de polystyrene expanse

Country Status (9)

Country Link
EP (1) EP0751859A1 (fr)
JP (1) JPH09510413A (fr)
KR (1) KR970701623A (fr)
CN (1) CN1146745A (fr)
AU (1) AU1869595A (fr)
BR (1) BR9507434A (fr)
CA (1) CA2186262A1 (fr)
CO (1) CO4410359A1 (fr)
WO (1) WO1995025625A1 (fr)

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
IT1281635B1 (it) * 1995-09-14 1998-02-20 Antonio Riglietti Metodo di realizzazione di contenitori multistrato monouso, particolarmente per sostanze deperibili e/o aggressive, nonche'
ATE301540T1 (de) 2001-01-26 2005-08-15 Reckitt Benckiser Uk Ltd Verfahren zur herstellung einer laminierten wärmegeformten folie
JP5684582B2 (ja) * 2011-01-19 2015-03-11 株式会社積水技研 樹脂発泡成形品の製造方法、及び、樹脂発泡成形品の製造設備
CA2874498A1 (fr) 2012-05-22 2013-11-28 Owens Corning Intellectual Capital, Llc Produit en mousse stratifie et procedes de fabrication de produits en mousse stratifies
CN103350512A (zh) * 2013-06-21 2013-10-16 英特普制品有限公司 一种热成型垫的成型装置
KR101724956B1 (ko) * 2015-12-02 2017-04-10 현대자동차주식회사 차량용 사이드 스텝의 제조방법
CN106696299B (zh) * 2017-01-17 2023-10-27 罗松 一种发泡聚乙烯材质的包装容器的造型加工工艺流程
CN106903904B (zh) * 2017-04-07 2023-03-28 罗松 一种造型加工发泡聚乙烯产品的机械设备及使用方法

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3589592A (en) * 1967-03-01 1971-06-29 Dow Chemical Co Foam receptacle
US4411849A (en) * 1981-08-03 1983-10-25 James River-Dixie/Northern, Inc. Method for forming a plurality of objects from a plurality of superimposed sheets
US4476183A (en) * 1983-11-21 1984-10-09 Monsanto Company Thermoformable laminate structure with improved acoustical absorption
US4595551A (en) * 1984-09-21 1986-06-17 Monsanto Company Thermoforming of styrenic foam laminates
US5250577A (en) * 1989-08-02 1993-10-05 The Dow Chemical Company Polystyrene foam made with only carbon dioxide as a blowing agent and a process for making the same

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9525625A1 *

Also Published As

Publication number Publication date
CO4410359A1 (es) 1997-01-09
KR970701623A (ko) 1997-04-12
WO1995025625A1 (fr) 1995-09-28
JPH09510413A (ja) 1997-10-21
AU1869595A (en) 1995-10-09
CN1146745A (zh) 1997-04-02
BR9507434A (pt) 1997-09-16
CA2186262A1 (fr) 1995-09-28

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