Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
  • B22F3/22—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces for producing castings from a slip
  • B22F3/225—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces for producing castings from a slip by injection molding
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
  • B22F1/10—Metallic powder containing lubricating or binding agents; Metallic powder containing organic material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
  • B22F1/10—Metallic powder containing lubricating or binding agents; Metallic powder containing organic material
  • B22F1/103—Metallic powder containing lubricating or binding agents; Metallic powder containing organic material containing an organic binding agent comprising a mixture of, or obtained by reaction of, two or more components other than a solvent or a lubricating agent
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L91/00—Compositions of oils, fats or waxes; Compositions of derivatives thereof
  • C08L91/06—Waxes
• • G—PHYSICS
  • G04—HOROLOGY
  • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
  • G04B37/00—Cases
  • G04B37/22—Materials or processes of manufacturing pocket watch or wrist watch cases
• • G—PHYSICS
  • G04—HOROLOGY
  • G04D—APPARATUS OR TOOLS SPECIALLY DESIGNED FOR MAKING OR MAINTAINING CLOCKS OR WATCHES
  • G04D3/00—Watchmakers' or watch-repairers' machines or tools for working materials

Definitions

• the invention relates to an injection molding binder composition and an injection molding composition (feedstock) for producing metal shaped parts.
• the term "metal” will be referred to as the inorganic synthesis material obtained, whatever the nature of the metal or of the metal alloy.
• the basic raw materials are of different types, in general, and comprise at least on the one hand metal powder and on the other hand organic binders, such as resins or plastics or the like which allow the injection and the good mechanical strength of the component made with the mixture of all the raw materials. Other additives may be incorporated into the mixture. These raw materials can also be of different textures: solid, powdery, liquid, or pasty.
• the mixture can furthermore change its structure during its preparation, in particular, and without limitation, when complementary components of a resin undergo a polymerization reaction.
• the overall process of manufacturing a metal component by the powder technology comprises at least the following steps:
• - Pressing in particular in a molding chamber, a quantity of powder or granules feedstock resulting from mixing and granulation, for producing a component blank.
• This pressing can be carried out by injection, under pressure, in particular in a screw injector comprising means for heating this quantity of powder or feedstock granules resulting from kneading and granulation;
• the object of the invention is more particularly to provide a binder for an optimized injection molding composition which facilitates the kneading in metallurgy of powders for obtaining metals, so as to obtain a production of metal parts of complex shapes and having a very reproducible quality, with a controlled withdrawal coefficient.
• Thermoplastic materials are already known for the manufacture of metal moldings which contain a sinterable metal powder and a polymeric organic binder, the latter consisting essentially of a mixture of polyoxymethylene and polyoxymethylene and polyoxolane copolymers, such materials (feedstocks) are for example sold by the company BASF under the commercial designation Catamold®.
• a binder for injection molding composition comprising a polymeric base, a mixture of waxes and / or palm oil and a surfactant.
• debinding is carried out according to two successive distinct stages, namely in a first step of partial debinding with the aid of a solvent followed by a second thermal debinding step.
• the solvent-soluble components of the binder namely the wax mixture and the surfactant and the acrylic resins, are removed. This operation is carried out in practice in a batch in an oven containing green parts and appropriate solvents.
• the batch is then placed in a batch oven in which the undissolved binder components in the chemical debinding step are removed generally by bringing the "green" pieces to a temperature of the order of 600 ° C.
• the parts are sintered in the same oven by bringing them to a temperature of about 1200 ° C.
• the object of the present invention is to provide a binder for injection molding composition which obviates the aforementioned drawbacks, and more particularly which aims to improve the homogeneity and fluidity of the feedstock to allow the manufacture of metal parts of shapes. more complex, to reduce the cycle time in production, to limit or even eliminate the mechanical recoveries, and finally which eliminates the need to use environmentally aggressive products for the elimination of the organic binder, replacing them with non-polluting solvents that can be removed by simple heat treatment.
• the thermal debinding step can be shortened and allows for example the use of a band oven and thus optimize production rates while ensuring that debinding is completely done before the operation of sintering.
• this binder composition has a viscosity for injecting shapes of complex parts without defects.
• the binder of the invention comprises from 4 to 5% by volume of one of said copolymers or of their mixtures, between 25% and 30% by volume of polyethylene, 3 to 5% by volume of polypropylene and from 8 to 10% by volume of acrylic resin.
• the copolymer of ethylene and methacrylic or acrylic acid contains from 3 to 10% by weight.
• methacrylic or acrylic comonomer, and the ethylene-anhydride copolymer is a random (random) copolymer of ethylene and maleic anhydride having a melting point of 100 to 110 ° C or a copolymer of polyethylene HD and a modified anhydride having a melting point of 130 to 134 ° C.
• the acrylic resin has a molecular weight between 50,000 and 22,000 and an inherent viscosity of 0.21 to 0.83, and is selected from the group consisting of isobutyl methacrylate, methyl, ethyl and N-butyl, and methacrylate copolymers of isobutyl and N-butyl and methyl and N-butyl methacrylates or a mixture of these polymers and / or copolymers.
• the inherent viscosity corresponds to the viscosity of a solution containing 0.25 g of polymer in 50 ml of methylene chloride measured at 20 ° C. using a Cannon-Fenske No. 50 viscometer.
• the wax mixture comprises a wax of Carnauba and a paraffin wax or wax mixture includes a Carnauba wax and a palm oil.
• the surfactant is a NN'-ethylene-bis (stearamide) or a mixture of stearic and palmitic acids (stearin), or a mixture of these elements.
• the surfactant and the acrylic resins are soluble in isopropyl alcohol and / or turpentine.
• the invention also relates to an injection molding composition (feedstock) for the manufacture of metal shaped parts comprising 70 to 80% vol. a metal powder and 20 to 30% vol. binder comprising:
• the polymeric base contains copolymers of ethylene and methacrylic or acrylic acid, or copolymers of ethylene comprising maleic anhydride or a mixture of these copolymers as well as polyethylene, polypropylene and an acrylic resin, the respective amounts of the binder components being such that they are added together, they do not exceed 100% by volume and preferably are equal to 100% by volume.
• the metal powder of the injection molding composition may be chosen from the group comprising a metal tungsten powder, a stainless steel powder, a titanium metal powder, a noble metal powder such as gold, platinum, silver, palladium, rhodium and Ruthenium or a mixture of these metallic powders.
• a metal tungsten powder such as gold, platinum, silver, palladium, rhodium and Ruthenium or a mixture of these metallic powders.
• the polymeric portion of the binder is mixed with a stainless steel powder (typically 316L steel powder) at a temperature of about 150 ° C to form a premix.
• a stainless steel powder typically 316L steel powder
• To this premix are added the waxes and the surfactant, and the temperature is again increased to about 180 ° C to form a kind of homogeneous paste.
• This paste is then cooled and milled simultaneously to room temperature to form a powder.
• This powder then feeds a calender machine that shears and granulates the premix.
• the product of this last step is retained to constitute the feedstock that can be used in the manufacture of an injection-shaped part according to a known technique.
• 46.5 kg of the stainless steel (316L) metal powder (78% vol) and 3.5 kg of the binder (about 22% vol) having the following volume composition:
• paraffin wax for example of the type "Carisma 56 T (TM)" from Alpha Wax BV

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Mechanical Engineering (AREA)
• General Physics & Mathematics (AREA)
• Physics & Mathematics (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Health & Medical Sciences (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Powder Metallurgy (AREA)
• Adhesives Or Adhesive Processes (AREA)

Applications Claiming Priority (2)

Publications (1)

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• 2016
  • 2016-12-08 EP EP16203041.5A patent/EP3332897A1/de not_active Withdrawn
• 2017
  • 2017-10-17 US US16/462,112 patent/US20190315964A1/en not_active Abandoned
  • 2017-10-17 JP JP2019528447A patent/JP2019535881A/ja active Pending
  • 2017-10-17 WO PCT/EP2017/076486 patent/WO2018103931A1/fr unknown
  • 2017-10-17 CN CN201780075637.9A patent/CN110062675A/zh active Pending
  • 2017-10-17 EP EP17783879.4A patent/EP3551367A1/de active Pending
• 2021
  • 2021-01-15 JP JP2021004864A patent/JP7029555B2/ja active Active

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