WO2006040776A1 - Procede de fabrication de moules en plastique pour realiser des articles expanses - Google Patents

Procede de fabrication de moules en plastique pour realiser des articles expanses Download PDF

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Publication number
WO2006040776A1
WO2006040776A1 PCT/IN2004/000317 IN2004000317W WO2006040776A1 WO 2006040776 A1 WO2006040776 A1 WO 2006040776A1 IN 2004000317 W IN2004000317 W IN 2004000317W WO 2006040776 A1 WO2006040776 A1 WO 2006040776A1
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WO
WIPO (PCT)
Prior art keywords
punch
box
mould
mass
heated
Prior art date
Application number
PCT/IN2004/000317
Other languages
English (en)
Inventor
Pulin Jayantilal Shah
Original Assignee
Pulin Jayantilal Shah
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 Pulin Jayantilal Shah filed Critical Pulin Jayantilal Shah
Priority to PCT/IN2004/000317 priority Critical patent/WO2006040776A1/fr
Publication of WO2006040776A1 publication Critical patent/WO2006040776A1/fr

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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
    • B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
    • B29C43/02—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor of articles of definite length, i.e. discrete articles
    • B29C43/14—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor of articles of definite length, i.e. discrete articles in several steps
    • 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
    • B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
    • B29C43/003—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor characterised by the choice of material
    • 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
    • B29K2023/00—Use of polyalkenes or derivatives thereof as moulding material
    • B29K2023/04—Polymers of ethylene
    • B29K2023/06—PE, i.e. polyethylene
    • B29K2023/0658—PE, i.e. polyethylene characterised by its molecular weight
    • B29K2023/0683—UHMWPE, i.e. ultra high molecular weight polyethylene
    • 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
    • B29K2075/00—Use of PU, i.e. polyureas or polyurethanes or derivatives thereof, as moulding material
    • 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
    • B29K2105/0002—Condition, form or state of moulded material or of the material to be shaped monomers or prepolymers

Definitions

  • the present invention relates to the method of preparation of a mould for making cold cure foam products, which will allow release of molded PU part without the use of release agent.
  • Release agents are routinely used to prevent the foam products from sticking to the mould surface i.e. to act as a barrier layer between the foam products and the mould.
  • Polyurethane are a mix of two components: ISOCYA N ATES-com prising of Toluene di lsocyanate and/or Di-methelene-di-lsocyante having free NCO groups which reacts with hydroxile groups present in the Polyols. Catalysts and Blowing agents are present within the POLYOL, along with other additives. When reacted with NCO group they form a long chain, which is known as Polyurethane.
  • Blowing agents generally water is available in small quantities, which on reacting with NCO group of ISO liberates Carbon dioxide, the liberated CO 2 forms micro cells in the rising foam.
  • Amine catalysts and organic tin compounds are added to hasten / control the reaction.
  • the blowing agents present in form of water or in liquefied gaseous liberates at its boiling point due to exothem reactivity.
  • the resultant mix while extending its chain incorporates liberated gas from the blowing agent and becomes viscous and micro-cellular and gradually achieves solid state.
  • This mix thus formed starts to form long chain.
  • the cross-linking action forms honeycomb like structure, radiating form the bottom of the mould to mould's outer walls. Once this sold state is achieved and the resultant mix starts to condense, a sticky skin like outer covering is formed. This sticky outer skin sticks to the surface of the mould.
  • release agents are generally wax or silicon suspended in aromatic solution hence on application of the release agent to the mould surface, the medium evaporates leaving behind a very fine Patina of wax or silicon on the mould surface. This Patina, adheres to reacted mix and releases itself from the mould. The release agent shears off from the mould surface and hence the need for re-applying release agent.
  • Existing technology includes following:
  • a fine spray of silicon/wax suspended in aromatic compounds is applied to the mould surface, the solution on spraying gets exposed to the atmosphere and the solvent evaporates leaving a fine non-permeable layer of wax or silicon on the mould surface.
  • the layer transfers on to Polyurethane foam which is rising and getting sticks to the thin layer of wax/silicon spray and on demolding releases itself from the mould along with the release agent film.
  • This release agent has to be applied after every shot.
  • the need of the hour is to develop a release medium, which instead of sticking to the foam, should adhere to the mould surface and allow of foam, from mold surface then there will be no need to re-apply the release agent.
  • the need is to develop a mould such that the surface of the mould is joint less and glossy to prevent the formation of the micro cells, as the adhesion of the foam to the surface is basically due to the micro- porosity of the cavity material and the cross linking property of the chemical mix. It is proposed to use such mold to make polyurethane moldings, of any shape, size by making molds which allows self-release.
  • this invention seeks to do away with the old method of manufacture. Accordingly, this invention relates to a method for manufacture of a moulds suitable to produce cold cure foam products without the use of a release agent.
  • the principle aim of this invention is to overcome the aforementioned drawbacks found in the current method of manufacture.
  • This invention provides for a method of manufacturer of a mould for cold cure foam products by using Polyolefin powder as a base material for making release agent free moulds wherein the surface is joint less and glossy which will prevent the formation of micro-cells which encourages sticking. Such surfaces cannot be machined but are manufactured.
  • Polyolefin derivates like Polypropelene (PP), High Density Polyethelene (HDPE).UItra High Molecular Weight High Density Polythelene (UHMWHDPE), linear Low Density Polyethelene (LLDPE) etc. has the lowest coefficient of friction after Polytetraflouroethylene (PTFE). These are commercially available and are comparatively easier to handle in terms of their processing ability.
  • Fig 1 shows the hollow metal box C in which variants of polyolefin powder is filled.
  • This box C has ridges R on the sidewalls W 1 and W 2.
  • Hinges H are placed at the juncture of the sidewalls W 1 and W 2 and the bottom of the metal box C. The placement of Ridges & Hinges will depend upon the mold design.
  • Fig 2 Shows the charging of the powdered polyolefin in the box C.
  • Fig. 3 shows the punch A in the shape of the article to be produced attached to the platen B.
  • the bottom platen P is also marked.
  • Fig. 4 shows full compaction of the punch A over metal box C, packing the powder completely. Heating of all plates and punch is done electrically or with any other medium to melt the powder and make the whole mass as one piece.
  • Fig. 5 shows withdrawal of the punch A from the box C, opening the sidewalls W1 and W2 of the box C side ways by means of the hinges H.
  • Fig. 6 shows the solidified mould cavity with external rib projections, which is ready for metal braces.
  • Fig. 7 shows the top plate D backed with metal webbing and braced with angles to allow fixing of hinges and clamps.
  • HDPE Polyethylene
  • HDPE powder of suitable grade in the range of 500 mesh to 800 mesh (particle size) and molecular weight between 200000 and 250000 is mixed with a chemical cross linker namely, Benzoyl peroxide thoroughly by hand or by dry tumbling in such a manner that the resultant mix forms a homogeneous mass.
  • the said cross linker is present in the said resultant roughly in the proportion 3 parts of the cross linker to one hundred parts of the powder.
  • a metal box C is made of mild steel plates is fitted with electrical heater bands to impart equal heating from all sides. The box C can also be heated by hot oil.
  • the box C has ridges R to accommodate the molten polyolefin derivative, which enables rib formation on the mould at various places for giving rigidity to the ultimate mold and for better heat dissipation.
  • the box C is placed on a heated platen P to allow even heating from the bottom also.
  • a punch A which is in the actual shape of the product (after providing shrinkage allowance) to be produced, is made of Aluminum, Zinc or Steel and is highly polished, is heated by electricity or oil. This punch A is fixed on to platen B.
  • the box C along with the punch A are heated upio glass transition temperatures between 200° C and 270° C.
  • the said mass is transferred to the metal box C either manually or by a mechanical device and charged, the charge calculated from volume of the metal box C.
  • the said mass fills the mould cavity by volume to ensure packing of material and prevent air embolism and spreads and fills the hollow spaces in the box C.
  • the heated punch A is then slowly lowered to compress the charged mass.
  • the mass is now evenly distributed between the punch A and the restraining box C.
  • the punch A is lifted up once to release any air trapped in the cavity of the box C . , to top up the said mass, if necessary, and is once more brought down to ensure that no air gap is left.
  • the mass Once the mass is heated . , compressed and pressurized, the said mass reaches the Glass Transition Phase and flows and takes the shape of the recess available into the box A and the restraining metal box C.
  • the punch A and the metal box C are then allowed to cool naturally to room temperature.
  • Product size 0.3mt x O.Smtx 0.3mt square block with 50mm thickness all around.
  • Metal Box C The following are the specifications to which the cavity C is to be built:
  • the UHMWHDPE Powder is mixed with cross-linker Benzoyle Peroxide (2 pbw) by dry tumbling to form a homogenous mass.
  • the metal box C along with the punch A is heated to 260° C and fotaJ powder is transferred into the box C.
  • the mass is then charged and the weight of charge is 2 Kg.
  • the punch A is lowered gradually into the heated box C at the rate of 10 to 15 mm per 30 seconds to compress the charged mass.
  • the said mass is now compressed within the recess provided between the punch A and the box C.
  • the punch A is then slowly taken upwards to allow the air trapped in box C to escape and then immediately lowered and the said mass is once again compressed fully under 100kg/cm pressure for about 20 minutes, till the said mass reaches Glass Transition Phase and flows.
  • the powder solidifies and acquires the shape provided between the punch A and the metal box C.
  • the box is opened from three sides, that is, the punch A is lifted and the two side wails W1 and W2 are opened sideways by using force and the force applied is lOOOKg/Sq.Cm.
  • the mould is now ready for making cold cure foam products.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Casting Or Compression Moulding Of Plastics Or The Like (AREA)
  • Moulds For Moulding Plastics Or The Like (AREA)

Abstract

Selon l'invention, un mélange de poudre polyoléfinique et de peroxyde de benzoyle servant de réticulant est transféré dans un châssis. Ce châssis est préchauffé en même temps qu'un poinçon. Le poinçon chauffé est descendu progressivement dans le châssis métallique pour comprimer la matière à mouler. Le poinçon est ensuite relevé pour libérer l'air éventuellement piégé et une quantité additionnelle de matière est transférée dans le châssis si nécessaire. Le poinçon est à nouveau descendu pour comprimer la matière et il est chauffé jusqu'à ce que celle-ci atteigne la phase de transition vitreuse et prenne la forme de la cavité formée entre le poinçon et le châssis (procédé de moulage par compression).
PCT/IN2004/000317 2004-10-12 2004-10-12 Procede de fabrication de moules en plastique pour realiser des articles expanses WO2006040776A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/IN2004/000317 WO2006040776A1 (fr) 2004-10-12 2004-10-12 Procede de fabrication de moules en plastique pour realiser des articles expanses

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/IN2004/000317 WO2006040776A1 (fr) 2004-10-12 2004-10-12 Procede de fabrication de moules en plastique pour realiser des articles expanses

Publications (1)

Publication Number Publication Date
WO2006040776A1 true WO2006040776A1 (fr) 2006-04-20

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/IN2004/000317 WO2006040776A1 (fr) 2004-10-12 2004-10-12 Procede de fabrication de moules en plastique pour realiser des articles expanses

Country Status (1)

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WO (1) WO2006040776A1 (fr)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2899708A (en) * 1959-08-18 Modification and control of plastic
US3931373A (en) * 1971-12-21 1976-01-06 J. O. Beattie Research Company Replication processes for producing plastic optical components
US4073844A (en) * 1975-03-22 1978-02-14 Sumitomo Chemical Company, Limited Preparation of crosslinked polyolefin foams and the mold
EP1250994A1 (fr) * 2001-04-09 2002-10-23 Nissen Chemitec Corporation Méthode de fabrication d'un produit moussé
GB2397549A (en) * 2003-01-23 2004-07-28 Advanced Composites Group Ltd A foam body for a master model

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2899708A (en) * 1959-08-18 Modification and control of plastic
US3931373A (en) * 1971-12-21 1976-01-06 J. O. Beattie Research Company Replication processes for producing plastic optical components
US4073844A (en) * 1975-03-22 1978-02-14 Sumitomo Chemical Company, Limited Preparation of crosslinked polyolefin foams and the mold
EP1250994A1 (fr) * 2001-04-09 2002-10-23 Nissen Chemitec Corporation Méthode de fabrication d'un produit moussé
GB2397549A (en) * 2003-01-23 2004-07-28 Advanced Composites Group Ltd A foam body for a master model

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