US20120087823A1 - Method for producing porous metal sintered molded bodies - Google Patents
Method for producing porous metal sintered molded bodies Download PDFInfo
- Publication number
- US20120087823A1 US20120087823A1 US13/375,315 US201013375315A US2012087823A1 US 20120087823 A1 US20120087823 A1 US 20120087823A1 US 201013375315 A US201013375315 A US 201013375315A US 2012087823 A1 US2012087823 A1 US 2012087823A1
- Authority
- US
- United States
- Prior art keywords
- process according
- polymer particles
- metal powder
- sinterable metal
- expandable polymer
- 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.)
- Abandoned
Links
- 229910052751 metal Inorganic materials 0.000 title claims abstract description 57
- 239000002184 metal Substances 0.000 title claims abstract description 57
- 238000004519 manufacturing process Methods 0.000 title abstract description 8
- 229920000642 polymer Polymers 0.000 claims abstract description 70
- 239000002245 particle Substances 0.000 claims abstract description 60
- 239000000843 powder Substances 0.000 claims abstract description 53
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 24
- 238000010438 heat treatment Methods 0.000 claims abstract description 19
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 11
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims abstract description 10
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 10
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 9
- PPBRXRYQALVLMV-UHFFFAOYSA-N Styrene Chemical compound C=CC1=CC=CC=C1 PPBRXRYQALVLMV-UHFFFAOYSA-N 0.000 claims abstract description 9
- 229910052802 copper Inorganic materials 0.000 claims abstract description 9
- 239000010949 copper Substances 0.000 claims abstract description 9
- 229910052742 iron Inorganic materials 0.000 claims abstract description 7
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims abstract description 5
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 5
- 239000010936 titanium Substances 0.000 claims abstract description 5
- 229910052719 titanium Inorganic materials 0.000 claims abstract description 5
- 238000000034 method Methods 0.000 claims description 32
- 239000004604 Blowing Agent Substances 0.000 claims description 22
- OFBQJSOFQDEBGM-UHFFFAOYSA-N Pentane Chemical group CCCCC OFBQJSOFQDEBGM-UHFFFAOYSA-N 0.000 claims description 12
- 150000001338 aliphatic hydrocarbons Chemical group 0.000 claims description 2
- 229920001577 copolymer Polymers 0.000 claims description 2
- 150000008282 halocarbons Chemical class 0.000 claims description 2
- 239000011230 binding agent Substances 0.000 description 23
- 239000000203 mixture Substances 0.000 description 23
- 239000008188 pellet Substances 0.000 description 15
- 238000005245 sintering Methods 0.000 description 15
- 239000000155 melt Substances 0.000 description 13
- 238000005187 foaming Methods 0.000 description 12
- 239000006262 metallic foam Substances 0.000 description 11
- 238000000465 moulding Methods 0.000 description 11
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 10
- 239000004793 Polystyrene Substances 0.000 description 10
- 229920002223 polystyrene Polymers 0.000 description 10
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 9
- 238000002844 melting Methods 0.000 description 8
- 239000005350 fused silica glass Substances 0.000 description 7
- 238000005453 pelletization Methods 0.000 description 7
- -1 titanium hydride Chemical compound 0.000 description 7
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 6
- 239000006260 foam Substances 0.000 description 6
- 239000001257 hydrogen Substances 0.000 description 6
- 229910052739 hydrogen Inorganic materials 0.000 description 6
- 238000004898 kneading Methods 0.000 description 6
- 230000008018 melting Effects 0.000 description 6
- 239000007789 gas Substances 0.000 description 5
- 238000002156 mixing Methods 0.000 description 5
- 229910052757 nitrogen Inorganic materials 0.000 description 5
- 229910052573 porcelain Inorganic materials 0.000 description 5
- 239000011324 bead Substances 0.000 description 4
- 238000001816 cooling Methods 0.000 description 4
- 238000001125 extrusion Methods 0.000 description 4
- 239000011261 inert gas Substances 0.000 description 4
- QWTDNUCVQCZILF-UHFFFAOYSA-N isopentane Chemical compound CCC(C)C QWTDNUCVQCZILF-UHFFFAOYSA-N 0.000 description 4
- 238000000197 pyrolysis Methods 0.000 description 4
- 229920001169 thermoplastic Polymers 0.000 description 4
- 229910045601 alloy Inorganic materials 0.000 description 3
- 239000000956 alloy Substances 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 238000011049 filling Methods 0.000 description 3
- 229920005669 high impact polystyrene Polymers 0.000 description 3
- 239000004797 high-impact polystyrene Substances 0.000 description 3
- 238000001746 injection moulding Methods 0.000 description 3
- 229910001092 metal group alloy Inorganic materials 0.000 description 3
- 229920006393 polyether sulfone Polymers 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 239000004952 Polyamide Substances 0.000 description 2
- 239000004698 Polyethylene Substances 0.000 description 2
- 239000004743 Polypropylene Substances 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 2
- 240000007591 Tilia tomentosa Species 0.000 description 2
- XECAHXYUAAWDEL-UHFFFAOYSA-N acrylonitrile butadiene styrene Chemical compound C=CC=C.C=CC#N.C=CC1=CC=CC=C1 XECAHXYUAAWDEL-UHFFFAOYSA-N 0.000 description 2
- 229920000122 acrylonitrile butadiene styrene Polymers 0.000 description 2
- 239000004676 acrylonitrile butadiene styrene Substances 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 239000010941 cobalt Substances 0.000 description 2
- 229910017052 cobalt Inorganic materials 0.000 description 2
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 2
- 238000005056 compaction Methods 0.000 description 2
- AFABGHUZZDYHJO-UHFFFAOYSA-N dimethyl butane Natural products CCCC(C)C AFABGHUZZDYHJO-UHFFFAOYSA-N 0.000 description 2
- 150000002191 fatty alcohols Chemical class 0.000 description 2
- 239000012774 insulation material Substances 0.000 description 2
- 229940087654 iron carbonyl Drugs 0.000 description 2
- NNPPMTNAJDCUHE-UHFFFAOYSA-N isobutane Chemical compound CC(C)C NNPPMTNAJDCUHE-UHFFFAOYSA-N 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- LYRFLYHAGKPMFH-UHFFFAOYSA-N octadecanamide Chemical compound CCCCCCCCCCCCCCCCCC(N)=O LYRFLYHAGKPMFH-UHFFFAOYSA-N 0.000 description 2
- 229920003229 poly(methyl methacrylate) Polymers 0.000 description 2
- 229920002647 polyamide Polymers 0.000 description 2
- 229920001707 polybutylene terephthalate Polymers 0.000 description 2
- 229920000573 polyethylene Polymers 0.000 description 2
- 229920000139 polyethylene terephthalate Polymers 0.000 description 2
- 239000005020 polyethylene terephthalate Substances 0.000 description 2
- 239000004926 polymethyl methacrylate Substances 0.000 description 2
- 229920001955 polyphenylene ether Polymers 0.000 description 2
- 229920001155 polypropylene Polymers 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 238000003825 pressing Methods 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 239000004416 thermosoftening plastic Substances 0.000 description 2
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 2
- 229910052721 tungsten Inorganic materials 0.000 description 2
- 239000010937 tungsten Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- ULQISTXYYBZJSJ-UHFFFAOYSA-N 12-hydroxyoctadecanoic acid Chemical compound CCCCCCC(O)CCCCCCCCCCC(O)=O ULQISTXYYBZJSJ-UHFFFAOYSA-N 0.000 description 1
- KIHBGTRZFAVZRV-UHFFFAOYSA-N 2-Hydroxyoctadecanoic acid Natural products CCCCCCCCCCCCCCCCC(O)C(O)=O KIHBGTRZFAVZRV-UHFFFAOYSA-N 0.000 description 1
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229920005682 EO-PO block copolymer Polymers 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- 229920003171 Poly (ethylene oxide) Polymers 0.000 description 1
- 229920002367 Polyisobutene Polymers 0.000 description 1
- 239000004721 Polyphenylene oxide Substances 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- 235000021355 Stearic acid Nutrition 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- 238000004026 adhesive bonding Methods 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 238000013019 agitation Methods 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 239000007900 aqueous suspension Substances 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 238000000889 atomisation Methods 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- BZDKYAZTCWRUDZ-UHFFFAOYSA-N buta-1,3-diene;methyl 2-methylprop-2-enoate;prop-2-enenitrile;styrene Chemical compound C=CC=C.C=CC#N.COC(=O)C(C)=C.C=CC1=CC=CC=C1 BZDKYAZTCWRUDZ-UHFFFAOYSA-N 0.000 description 1
- NOQOJJUSNAWKBQ-UHFFFAOYSA-N buta-1,3-diene;methyl prop-2-enoate;styrene Chemical compound C=CC=C.COC(=O)C=C.C=CC1=CC=CC=C1 NOQOJJUSNAWKBQ-UHFFFAOYSA-N 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 125000004432 carbon atom Chemical group C* 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 150000001728 carbonyl compounds Chemical class 0.000 description 1
- 125000002915 carbonyl group Chemical group [*:2]C([*:1])=O 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 230000001413 cellular effect Effects 0.000 description 1
- 210000003850 cellular structure Anatomy 0.000 description 1
- 238000005253 cladding Methods 0.000 description 1
- 229910052681 coesite Inorganic materials 0.000 description 1
- 230000001427 coherent effect Effects 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 229910052906 cristobalite Inorganic materials 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 239000002270 dispersing agent Substances 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 150000002148 esters Chemical class 0.000 description 1
- 150000002170 ethers Chemical class 0.000 description 1
- 229920006248 expandable polystyrene Polymers 0.000 description 1
- 239000004794 expanded polystyrene Substances 0.000 description 1
- 230000009969 flowable effect Effects 0.000 description 1
- 238000005243 fluidization Methods 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- 125000005456 glyceride group Chemical group 0.000 description 1
- 238000005470 impregnation Methods 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 239000003112 inhibitor Substances 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- VAKIVKMUBMZANL-UHFFFAOYSA-N iron phosphide Chemical compound P.[Fe].[Fe].[Fe] VAKIVKMUBMZANL-UHFFFAOYSA-N 0.000 description 1
- 239000001282 iso-butane Substances 0.000 description 1
- 150000002576 ketones Chemical class 0.000 description 1
- 229910001338 liquidmetal Inorganic materials 0.000 description 1
- 230000033001 locomotion Effects 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 229910052987 metal hydride Inorganic materials 0.000 description 1
- 150000004681 metal hydrides Chemical class 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- VUZPPFZMUPKLLV-UHFFFAOYSA-N methane;hydrate Chemical compound C.O VUZPPFZMUPKLLV-UHFFFAOYSA-N 0.000 description 1
- 229920012128 methyl methacrylate acrylonitrile butadiene styrene Polymers 0.000 description 1
- QMQXDJATSGGYDR-UHFFFAOYSA-N methylidyneiron Chemical compound [C].[Fe] QMQXDJATSGGYDR-UHFFFAOYSA-N 0.000 description 1
- IJDNQMDRQITEOD-UHFFFAOYSA-N n-butane Chemical compound CCCC IJDNQMDRQITEOD-UHFFFAOYSA-N 0.000 description 1
- QIQXTHQIDYTFRH-UHFFFAOYSA-N octadecanoic acid Chemical compound CCCCCCCCCCCCCCCCCC(O)=O QIQXTHQIDYTFRH-UHFFFAOYSA-N 0.000 description 1
- OQCDKBAXFALNLD-UHFFFAOYSA-N octadecanoic acid Natural products CCCCCCCC(C)CCCCCCCCC(O)=O OQCDKBAXFALNLD-UHFFFAOYSA-N 0.000 description 1
- 229920000620 organic polymer Polymers 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920001643 poly(ether ketone) Polymers 0.000 description 1
- 229920000058 polyacrylate Polymers 0.000 description 1
- 239000004417 polycarbonate Substances 0.000 description 1
- 229920000515 polycarbonate Polymers 0.000 description 1
- 229920000728 polyester Polymers 0.000 description 1
- 229920000570 polyether Polymers 0.000 description 1
- 229920005596 polymer binder Polymers 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 229920000098 polyolefin Polymers 0.000 description 1
- 229920006327 polystyrene foam Polymers 0.000 description 1
- 238000007639 printing Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 239000004071 soot Substances 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 229940037312 stearamide Drugs 0.000 description 1
- 239000008117 stearic acid Substances 0.000 description 1
- 229910052682 stishovite Inorganic materials 0.000 description 1
- 239000011145 styrene acrylonitrile resin Substances 0.000 description 1
- 229920001909 styrene-acrylic polymer Polymers 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 238000005979 thermal decomposition reaction Methods 0.000 description 1
- 150000003568 thioethers Chemical class 0.000 description 1
- 229910000048 titanium hydride Inorganic materials 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 229910052905 tridymite Inorganic materials 0.000 description 1
- 238000003826 uniaxial pressing Methods 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
- 230000008016 vaporization Effects 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
- 239000011701 zinc Substances 0.000 description 1
- XOOUIPVCVHRTMJ-UHFFFAOYSA-L zinc stearate Chemical compound [Zn+2].CCCCCCCCCCCCCCCCCC([O-])=O.CCCCCCCCCCCCCCCCCC([O-])=O XOOUIPVCVHRTMJ-UHFFFAOYSA-L 0.000 description 1
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
- B22F3/10—Sintering only
- B22F3/11—Making porous workpieces or articles
-
- 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
- B22F3/10—Sintering only
- B22F3/11—Making porous workpieces or articles
- B22F3/1121—Making porous workpieces or articles by using decomposable, meltable or sublimatable fillers
- B22F3/1125—Making porous workpieces or articles by using decomposable, meltable or sublimatable fillers involving a foaming process
-
- 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
-
- 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
- C08J9/0066—Use of inorganic compounding ingredients
-
- 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
- C08J9/228—Forming foamed products
- C08J9/232—Forming foamed products by sintering expandable particles
-
- 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
- C08J2203/00—Foams characterized by the expanding agent
- C08J2203/14—Saturated hydrocarbons, e.g. butane; Unspecified hydrocarbons
Definitions
- the invention relates to a process for producing porous sintered shaped metal bodies.
- Metallic foams have some interesting properties: compared to the solid metal, their density is greatly reduced. However, they still have a high specific stiffness and strength. In the case of an impact, the cellular structure converts a great deal of kinetic energy into deformation energy and heat, so that metallic foams are well suited to incorporation in crash elements. Compared to polymer foams, metal foams have a significantly higher strength and heat resistance. Further potential applications include heat shields, filters, catalyst supports, sound-absorbing cladding or the production of very light, foam-filled rollers for the printing or paper industry.
- Metal foams can be produced in various ways.
- a metal powder and a pulverulent blowing agent e.g. titanium hydride powder (TiH 3 ) are mixed, processed by uniaxial pressing or extrusion to form a foamable semifinished part and heated to the melting point of the metal.
- the blowing agent liberates gases and foams the molten metal.
- the foam structure such as the relative density, pore size and the like changes.
- gas is blown into a metal melt and the foamed metal solidifies. To stabilize the bubbles in the melt, it is possible to add, for example, SiC particles to the melt.
- Shaped metallic bodies can be produced by injection molding of thermoplastic compositions comprising metal powders together with a polymer as organic binder. These are highly filled organic polymer molding compositions. After injection molding, extrusion or pressing of the thermoplastic composition to form a green body, the organic binder is removed and the binder-free green body obtained is sintered. Porous shaped metallic bodies can also be obtained by concomitant use of blowing agents.
- WO 2004/067476 discloses a process for producing a cellular sintered shaped body, in which metal powder is mixed with binder components and expandable polystyrene particles (EPS) are incorporated as blowing agent.
- EPS expandable polystyrene particles
- This thermoplastically flowable molding composition is introduced into a housing mold for expansion of the molding composition, converted into a molten state and foamed.
- the foamed molding composition is solidified, the organic components are removed and the shaped body which has been treated in this way is sintered.
- the foaming step should occur with formation of individual expanded polystyrene foam particles which each take up a closed three-dimensional space in the molding composition and have a narrow diameter distribution.
- binder and foamable material are necessarily different from one another. Production of the molding composition is complicated and requires numerous successive steps.
- shaped bodies having simple geometries are obtained by pressing of a pulverulent EPS-comprising molding composition to form pressed bodies and subsequent foaming by means of steam in a perforated mold.
- Geometrically complex moldings are said to be obtainable by shaping and foaming of the molding composition by means of known injection molding processes.
- the process has the disadvantage that the pores produced by the EPS particles are very large, as a result of which only few stabilizing struts remain in the shaped body and these are also inhomogeneously distributed.
- materials whose mechanical properties are unsatisfactory for many applications are obtained.
- DE 103 28 047 B3 describes a process for producing a component composed of metal foam, in which a plurality of metal foam building blocks which can be obtained by introduction of energy into and at least partial foaming of pellets comprising a metal powder and a blowing agent powder, e.g. a metal hydride, are arranged in three dimensions.
- the metal foam building blocks which have been arranged in this way are subjected to an after-treatment so that adjacent metal foam building blocks are joined to one another by positive locking, fusion and/or adhesively.
- a disadvantage of this process is that in the production of the metal foam building blocks it is possible for a partial collapse of the metal foam formed to occur, leading to uncontrollable formation of denser zones in the interior of a building block produced in this way and a low reproduction accuracy. Without adhesive bonding, the individual metal foam building blocks do not adhere to one another.
- the object is achieved by a process for producing porous sintered shaped metal bodies, wherein expandable polymer particles in which a sinterable metal powder is dispersed are foamed to form a shaped body and the green shaped body is subjected to a heat treatment in which the polymer is driven off and the sinterable metal powder sinters to give a porous sintered shaped metal body.
- the expandable polymer particles are introduced into a mold which is closed, preferably on all sides, after filling and the expandable polymer particles are foamed, for example by treatment with steam and/or hot air.
- the geometry (three-dimensional shape) of the mold usually corresponds to the desired geometry of the future molding.
- prefoaming the expandable polymer particles before introduction into the mold.
- the expandable polymer particles are heated with mechanical agitation, e.g. by fluidization by means of a hot gas, in particular air and/or steam.
- a hot gas in particular air and/or steam.
- Prefoamers which are suitable for this purpose are known to those skilled in the art from the production of EPS insulation materials. Temperatures of, for example, 60 to 120° C. are generally suitable. Under these conditions, the particles expand as a result of the vaporizing blowing agent and partially also as a result of the steam which has penetrated into them to form a closed-cell structure in the interior of the bead.
- the polymer particles do not fuse with one another and remain as discreet particles.
- the density of the future shaped bodies can be influenced via the degree of foaming which depends mainly on the duration of the heat treatment.
- the duration of the heat treatment in prefoaming is typically from 5 to 100 seconds.
- nonuniform expansion and filling of the mold can occur during foaming of the expandable polymer particles in the mold, with the expandable polymer particles in the vicinity of the heated walls of the mold expanding to a greater extent than particles in the interior of the mold.
- the mold is only partly filled with the (optionally prefoamed) expandable polymer particles.
- the polymer particles expand and positively fill the initially incompletely filled mold with foam.
- the polymer particles are fused to one another during this operation.
- Foaming is usually effected by heating to, for example, from 60 to 120° C., preferably from 70 to 110° C., e.g. by heating the filled mold by means of steam, hot air, boiling water or another heat transfer medium. Foaming increases the volume of the polymer component of the particles, with the interstices in the bed being filled out by the expanding polymer particles and a shape-producing assemblage of the individual particles occurring as a result of force interactions between the particles whose volumes are increasing.
- the polymer particles melt on the mutual contact surfaces, so that the polymer particles fuse together to give a shaped body (green body).
- the mold proscribes the shape and volume of the green body.
- the shaped body which has a sufficient green strength can be taken from the mold.
- the pressure during foaming is usually not critical and is generally from 0.05 to 2 bar.
- the duration of full foaming depends, inter alia, on the size and geometry and also the desired density of the molding and can vary within wide limits.
- the process of the invention starts out from expandable polymer particles in which a sinterable metal powder is dispersed.
- the expandable polymer particles are preferably free-flowing or flow readily.
- the proportion by weight of the dispersed sinterable metal powder, based on the total weight of polymer and sinterable metal powder, is preferably from 60 to 95% by weight, in particular from 65 to 90% by weight.
- the polymer forms a continuous (coherent) phase in which the sinterable metal powder is dispersed.
- the expandable polymer particles preferably comprise a physical blowing agent such as aliphatic hydrocarbons having from 2 to 7 carbon atoms, alcohols, ketones, ethers, halogenated hydrocarbons, carbon dioxide or water or mixtures thereof. Preference is given to isobutane, n-butane, isopentane or n-pentane or mixtures thereof.
- the expandable polymer particles generally comprise from 2 to 20% by weight, preferably from 3 to 15% by weight, of blowing agent, based on the polymer in the expandable polymer particles.
- the blowing agent is present in the expandable polymer particles as a molecular solution in the polymer and/or as included droplets.
- the expandable polymer particles are preferably essentially spherical, but another shape such as rod-shaped or lens-shaped pellets is also possible.
- the expandable polymer particles generally have a diameter (or length in the direction of the largest dimension in the case of nonspherical particles) of from 0.5 to 30 mm, in particular from 0.7 to 10 mm.
- the expandable polymer particles can be obtained in various ways.
- the expandable polymer particles can be obtained, for example, by producing expandable thermoplastic polymer pellets by mixing a blowing agent and a sinterable metal powder into a polymer melt and pelletizing the melt.
- the expandable polymer particles are preferably produced by means of an extrusion process.
- the blowing agent is mixed into a polymer melt via an extruder, the sinterable metal powder is mixed in and the polymer melt is pushed through a die plate and pelletized to give particles.
- the melt is usually cooled after introduction of the blowing agent.
- Each of these steps can be carried out by means of the apparatuses or apparatus combinations known in plastics processing.
- the polymer melt can be taken directly from a polymerization reactor or be produced in the mixing extruder or a separate melting extruder by melting of polymer pellets.
- Static or dynamic mixers are suitable for mixing in the blowing agent and the sinterable metal powder. Cooling of the melt can be carried out in the mixing apparatuses or in separate coolers.
- Possible pelletization methods are, for example, pressurized underwater pelletization, pelletization using rotating knives and cooling by spray misting of cooling liquids or pelletization by atomization.
- the sinterable metal powder is appropriately mixed in via a side extruder.
- a substream of the melt stream initially obtained can be branched off via a melt valve into a side stream before passage through the die plate.
- the metal powder is added to the side stream and mixed homogeneously into the melt stream.
- the main stream and the additive-comprising side stream are mixed and discharged via the die plate.
- the powder can be pasted beforehand. This means that it is incorporated into a liquid which is compatible with the melt and the metal powder so as to form a paste having a preferably high viscosity.
- a suitable protective gas such as nitrogen or argon is preferably passed through the apparatuses.
- pellets can firstly be produced by mixing a sinterable metal powder into a polymer melt and pelletizing the melt. These pellets can then be reshaped into beads in aqueous suspension in heated and stirred pressure vessels at temperatures in the vicinity of the softening point and at the same time impregnated with blowing agent. This conversion into beads gives bead-shaped particles having a defined particle size.
- the conversion into beads is generally carried out at from 120 to 160° C., e.g. about 140° C., over a period of from 1 to 24 hours, e.g. from 12 to 16 hours. Suitable processes are described, for example, in DE-A 25 34 833, DE-A 26 21 448, EP-A 53 333 and EP-6 95 109, which are fully incorporated by reference.
- the pellets can be impregnated with blowing agent under superatmospheric pressure at a temperature below the softening temperature of the polymer.
- the temperature can be, for example, from 25 to 60° C., e.g. about 40° C.
- a pressure-rated apparatus e.g. an autoclave, is charged with the pellets, the blowing agent is added in such an amount that it preferably completely covers the pellets and the apparatus is closed. Air is displaced by an inert gas such as nitrogen. The apparatus is then heated and the desired pressure is set. The pressure is established as autogenous pressure of the blowing agent at the treatment temperature or is set by injection of inert gas.
- sinterable metal powders mention may be made of, for example, aluminum, iron, in particular iron carbonyl powder, cobalt, copper, nickel, silicon, titanium and tungsten, among which aluminum, iron, copper, nickel and titanium are preferred.
- pulverulent metal alloys mention may be made by way of example of high- or low-alloy steels and also metal alloys based on aluminum, iron, titanium, copper, nickel, cobalt or tungsten.
- the metal powders, metal alloy powders and metal carbonyl powders can also be used in admixture.
- the melting points of the components of the mixture should not differ too much from one another, since otherwise the lower-melting component flows and the higher-melting component remains.
- the maximum melting point difference is preferably 800° C. or less, in particular 500° C. or less and most preferably 300° C. or less.
- Suitable metal powders are, for example, atomized metal powders which have been obtained by spraying of liquid metal with compressed gases.
- Carbonyl iron powder is preferred as metal powder.
- Carbon iron powder is an iron powder which is produced by thermal decomposition of iron carbonyl compounds. To maintain flowability and to prevent agglomeration, it can, for example, be coated with SiO 2 .
- Iron phosphide powder can preferably be concomitantly used as corrosion inhibitor.
- Carbonyl iron powder has a small and uniform particle size; the particles have an essentially spherical shape. The melt viscosity of the composites with polymers is therefore very low and the melting point is uniform. Suitable carbonyl iron powders are described, for example, in DE 10 2005 062 028.
- Further preferred metal powders are powders composed of aluminum and copper.
- the particle sizes of the powders are preferably from 0.1 to 80 ⁇ m, particularly preferably from 1.0 to 50 ⁇ m.
- Suitable polymers are thermoplastic polymers having a good uptake capacity for blowing agent, for example styrene polymers, polyamides (PA), polyolefins such as polypropylene (PP), polyethylene (PE) or polyethylene-propylene copolymers, polyacrylates such as polymethyl methacrylate (PMMA), polycarbonate (PC), polyesters such as polyethylene terephthalate (PET) or polybutylene terephthalate (PBT), polyether sulfones (PES), polyether ketones or polyether sulfides (PES) or mixtures thereof. Particular preference is given to using styrene polymers.
- PA polyamides
- PP polyolefins
- PE polyethylene
- PE polyethylene-propylene copolymers
- polyacrylates such as polymethyl methacrylate (PMMA), polycarbonate (PC)
- PET polyethylene terephthalate
- PBT polybutylene terephthalate
- PES polyether
- styrene polymers preference is given to using clear, colorless polystyrene (GPPS), high-impact polystyrene (HIPS), anionically polymerized polystyrene or high-impact polystyrene (A-IPS), styrene- ⁇ -methstyrene copolymers, acrylonitrile-butadiene-styrene polymers (ABS), styrene-acrylonitrile (SAN), acrylonitrile-styrene-acrylic ester (ASA), methyl acrylate-butadiene-styrene (MBS), methyl methacrylate-acrylonitrile-butadiene-styrene (MABS) polymers or mixtures thereof or with polyphenylene ether (PPE).
- GPPS clear, colorless polystyrene
- HIPS high-impact polystyrene
- A-IPS anionically polymerized polystyrene or high
- dispersants can optionally be added.
- examples are oligomeric polyethylene oxide having an average molecular weight from 200 to 600, stearic acid, stearamide, hydroxystearic acid, magnesium, calcium or zinc stearate, fatty alcohols, ethoxylated fatty alcohols, fatty alcohol sulfonates, ethoxylated glycerides and block copolymers of ethylene oxide and propylene oxide, and also polyisobutylene.
- the polymer is driven off by means of a heat treatment.
- the sinterable metal powder is sintered to give a porous sintered shaped body.
- the term “drive off” comprises upstream decomposition and/or pyrolysis steps.
- the heat treatment can be carried out in a single-stage or multistage process. Preference is given to driving off the polymer (binder removal) at a first temperature in a first step and sintering the resulting binder-free shaped body at a second temperature.
- the second temperature is generally at least 100° C. higher than the first temperature. If the shaped body is exposed directly to the sintering temperature, severe soot formation on the shaped metal body is frequently observed, presumably due to excessively rapid pyrolysis.
- Binder removal and the sintering process can be carried out in the same apparatus; however, different apparatuses can also be used.
- Suitable furnaces for carrying out binder removal and/or sintering are convection box furnaces, shaft retort furnaces, convection shuttle kilns, hood-type furnaces, elevator furnaces, muffle furnaces and tube furnaces.
- Belt furnaces, combi-chamber furnaces or shuttle kilns are suitable for carrying out the steps of binder removal and sintering in the same apparatus.
- the furnaces can be provided with facilities for setting a defined binder removal atmosphere and/or sintering atmosphere.
- the shaped body is preferably exposed suddenly to the binder removal temperature and not heated slowly to the binder removal temperature, since otherwise the polymer can run and the foam structure can be lost. It is thus generally not a good idea to leave the shaped body in the heating zone of the furnace during the heating phase.
- a tube furnace having a long interior tube and to position the specimen in the tube but outside the heating zone during the heating phase. As soon as the target temperature has been reached, the specimen can be pushed into the heating zone. Binder removal can be carried out industrially using, for example, belt furnaces in particular.
- Binder removal is preferably carried out in a defined atmosphere.
- preference is given to an inert atmosphere or reducing atmosphere, with a reducing atmosphere being particularly preferred.
- metals such as aluminum, zinc or copper
- a temperature of from 150 to 800° C. is generally suitable for binder removal.
- a temperature of about 700° C. has been found to be useful, and a temperature of from 400 to 600° C. has been found to be useful in the case of aluminum.
- the duration depends greatly on the size of the shaped bodies.
- Binder removal is followed by a sintering process.
- This sintering process can be carried out at a temperature of from 250 to 1500° C.
- a sintering temperature of from 900 to 1100° C. has been found to be useful, and a temperature of not more than 650° C. has been found to be useful in the case of aluminum.
- the sintering atmosphere can be matched to the metal used. In general, an inert atmosphere or reducing atmosphere is preferred, with a reducing atmosphere being particularly preferred.
- hydrogen or mixtures of hydrogen and inert gas e.g. a hydrogen/nitrogen mixture
- the mixture of hydrogen and inert gas preferably comprises at least 3% by volume of hydrogen.
- the shaped body can sometimes undergo “after-foaming” during pyrolysis. It can be advantageous to carry out the pyrolysis in a mold having perforated walls, with greater filling of the mold and also compaction and conglutination taking place.
- the pellets were then immersed in pentane S (80% of n-pentane, 20% of isopentane) and maintained at a pressure of 50 bar and a temperature of 40° C. in a pressure autoclave for 4 hours. This gave polymer particles loaded with about 5% by weight of pentane.
- pentane S 80% of n-pentane, 20% of isopentane
- the pellets were introduced into a closed cube-shaped steel mold having an edge length of 4 cm and the mold was heated to about 100° C. by means of steam for 10 minutes.
- the polymer particles expanded during this treatment and fused to give a green body which was taken from the mold.
- the green body was sawn into smaller cubes by means of a saw and subsequently placed in a porcelain boat in a fused silica tube.
- the fused silica tube was installed horizontally in a hinged high-temperature tube furnace (model LOBA 11-50 from HTM Reetz, Berlin, Germany). The fused silica tube projected out of the furnace at both ends.
- the porcelain boat was firstly placed in an outer end of the fused silica tube, i.e. outside the heating zone. Nitrogen was passed through the fused silica tube.
- the furnace was set to 700° C. As soon as the furnace reached a temperature of 700° C., the nitrogen flow was reduced by 50% from 20 l/h to 10 l/h and supplemented by a hydrogen flow of 10 l/h.
- the porcelain boat was subsequently pushed inside the fused silica tube into the middle of the furnace. After the specimen had reached a temperature of 700° C., it was left in the heating zone for 10 minutes. It was then pulled from the heating zone again to the end of the fused silica tube.
- the furnace was then set to 900° C. As soon as the set temperature had been reached, the porcelain boat was pushed back into the middle of the furnace. After a sintering temperature of 900° C. had been reached, the specimen was left in the heating zone for 15 minutes. The porcelain boat was then pulled out of the heating zone again and the furnace was switched off. After cooling, the specimen was taken out.
Abstract
The invention relates to a method for producing porous metal sintered molded bodies, wherein expandable polymer particles, in which a sinterable metal powder is dispersed, are expanded to form a molded body. The molded body is subjected to a heat treatment, wherein the polymer is expelled and the sinterable metal powder is sintered to form a porous metal sintered molded body. Preferably, styrol polymers are used. The sinterable metal powder is selected, for example, from aluminum, iron, copper, nickel, and titanium.
Description
- The invention relates to a process for producing porous sintered shaped metal bodies.
- Metallic foams have some interesting properties: compared to the solid metal, their density is greatly reduced. However, they still have a high specific stiffness and strength. In the case of an impact, the cellular structure converts a great deal of kinetic energy into deformation energy and heat, so that metallic foams are well suited to incorporation in crash elements. Compared to polymer foams, metal foams have a significantly higher strength and heat resistance. Further potential applications include heat shields, filters, catalyst supports, sound-absorbing cladding or the production of very light, foam-filled rollers for the printing or paper industry.
- Metal foams can be produced in various ways. In the “powder route”, a metal powder and a pulverulent blowing agent, e.g. titanium hydride powder (TiH3) are mixed, processed by uniaxial pressing or extrusion to form a foamable semifinished part and heated to the melting point of the metal. The blowing agent liberates gases and foams the molten metal. Depending on the time for which the temperature is held, the foam structure such as the relative density, pore size and the like changes. In the “melt route”, gas is blown into a metal melt and the foamed metal solidifies. To stabilize the bubbles in the melt, it is possible to add, for example, SiC particles to the melt.
- Shaped metallic bodies can be produced by injection molding of thermoplastic compositions comprising metal powders together with a polymer as organic binder. These are highly filled organic polymer molding compositions. After injection molding, extrusion or pressing of the thermoplastic composition to form a green body, the organic binder is removed and the binder-free green body obtained is sintered. Porous shaped metallic bodies can also be obtained by concomitant use of blowing agents.
- Thus, WO 2004/067476 discloses a process for producing a cellular sintered shaped body, in which metal powder is mixed with binder components and expandable polystyrene particles (EPS) are incorporated as blowing agent. This thermoplastically flowable molding composition is introduced into a housing mold for expansion of the molding composition, converted into a molten state and foamed. The foamed molding composition is solidified, the organic components are removed and the shaped body which has been treated in this way is sintered. The foaming step should occur with formation of individual expanded polystyrene foam particles which each take up a closed three-dimensional space in the molding composition and have a narrow diameter distribution. In this process, binder and foamable material are necessarily different from one another. Production of the molding composition is complicated and requires numerous successive steps.
- According to WO 2004/067476, shaped bodies having simple geometries are obtained by pressing of a pulverulent EPS-comprising molding composition to form pressed bodies and subsequent foaming by means of steam in a perforated mold. Geometrically complex moldings are said to be obtainable by shaping and foaming of the molding composition by means of known injection molding processes. The process has the disadvantage that the pores produced by the EPS particles are very large, as a result of which only few stabilizing struts remain in the shaped body and these are also inhomogeneously distributed. Finally, materials whose mechanical properties are unsatisfactory for many applications are obtained.
- DE 103 28 047 B3 describes a process for producing a component composed of metal foam, in which a plurality of metal foam building blocks which can be obtained by introduction of energy into and at least partial foaming of pellets comprising a metal powder and a blowing agent powder, e.g. a metal hydride, are arranged in three dimensions. The metal foam building blocks which have been arranged in this way are subjected to an after-treatment so that adjacent metal foam building blocks are joined to one another by positive locking, fusion and/or adhesively. A disadvantage of this process is that in the production of the metal foam building blocks it is possible for a partial collapse of the metal foam formed to occur, leading to uncontrollable formation of denser zones in the interior of a building block produced in this way and a low reproduction accuracy. Without adhesive bonding, the individual metal foam building blocks do not adhere to one another.
- It is an object of the invention to provide a process for producing porous sintered shaped metal bodies, which is free of the above disadvantages.
- The object is achieved by a process for producing porous sintered shaped metal bodies, wherein expandable polymer particles in which a sinterable metal powder is dispersed are foamed to form a shaped body and the green shaped body is subjected to a heat treatment in which the polymer is driven off and the sinterable metal powder sinters to give a porous sintered shaped metal body.
- In an advantageous embodiment, the expandable polymer particles are introduced into a mold which is closed, preferably on all sides, after filling and the expandable polymer particles are foamed, for example by treatment with steam and/or hot air. The geometry (three-dimensional shape) of the mold usually corresponds to the desired geometry of the future molding.
- In most cases, preference is given to prefoaming the expandable polymer particles before introduction into the mold. During prefoaming, the expandable polymer particles are heated with mechanical agitation, e.g. by fluidization by means of a hot gas, in particular air and/or steam. Prefoamers which are suitable for this purpose are known to those skilled in the art from the production of EPS insulation materials. Temperatures of, for example, 60 to 120° C. are generally suitable. Under these conditions, the particles expand as a result of the vaporizing blowing agent and partially also as a result of the steam which has penetrated into them to form a closed-cell structure in the interior of the bead. During prefoaming, the polymer particles do not fuse with one another and remain as discreet particles.
- The density of the future shaped bodies can be influenced via the degree of foaming which depends mainly on the duration of the heat treatment. The duration of the heat treatment in prefoaming is typically from 5 to 100 seconds.
- Without the prefoaming step, nonuniform expansion and filling of the mold can occur during foaming of the expandable polymer particles in the mold, with the expandable polymer particles in the vicinity of the heated walls of the mold expanding to a greater extent than particles in the interior of the mold.
- In general, the mold is only partly filled with the (optionally prefoamed) expandable polymer particles. During foaming, the polymer particles expand and positively fill the initially incompletely filled mold with foam. The polymer particles are fused to one another during this operation.
- Particularly in the case of complicated geometries, it can also be advantageous to keep the empty volume in the mold low and optionally compact the bed of the (optionally prefoamed) expandable polymer particles introduced into the mold and in this way eliminate undesirable voids. Compaction can be achieved, for example, by shaking of the mold, tumbling motions or other suitable measures.
- Foaming is usually effected by heating to, for example, from 60 to 120° C., preferably from 70 to 110° C., e.g. by heating the filled mold by means of steam, hot air, boiling water or another heat transfer medium. Foaming increases the volume of the polymer component of the particles, with the interstices in the bed being filled out by the expanding polymer particles and a shape-producing assemblage of the individual particles occurring as a result of force interactions between the particles whose volumes are increasing. The polymer particles melt on the mutual contact surfaces, so that the polymer particles fuse together to give a shaped body (green body). The mold proscribes the shape and volume of the green body. The shaped body which has a sufficient green strength can be taken from the mold.
- The pressure during foaming is usually not critical and is generally from 0.05 to 2 bar. The duration of full foaming depends, inter alia, on the size and geometry and also the desired density of the molding and can vary within wide limits.
- The process of the invention starts out from expandable polymer particles in which a sinterable metal powder is dispersed. The expandable polymer particles are preferably free-flowing or flow readily. The proportion by weight of the dispersed sinterable metal powder, based on the total weight of polymer and sinterable metal powder, is preferably from 60 to 95% by weight, in particular from 65 to 90% by weight. In the polymer particles, the polymer forms a continuous (coherent) phase in which the sinterable metal powder is dispersed.
- The expandable polymer particles preferably comprise a physical blowing agent such as aliphatic hydrocarbons having from 2 to 7 carbon atoms, alcohols, ketones, ethers, halogenated hydrocarbons, carbon dioxide or water or mixtures thereof. Preference is given to isobutane, n-butane, isopentane or n-pentane or mixtures thereof. The expandable polymer particles generally comprise from 2 to 20% by weight, preferably from 3 to 15% by weight, of blowing agent, based on the polymer in the expandable polymer particles. The blowing agent is present in the expandable polymer particles as a molecular solution in the polymer and/or as included droplets.
- The expandable polymer particles are preferably essentially spherical, but another shape such as rod-shaped or lens-shaped pellets is also possible. The expandable polymer particles generally have a diameter (or length in the direction of the largest dimension in the case of nonspherical particles) of from 0.5 to 30 mm, in particular from 0.7 to 10 mm.
- The expandable polymer particles can be obtained in various ways.
- The expandable polymer particles can be obtained, for example, by producing expandable thermoplastic polymer pellets by mixing a blowing agent and a sinterable metal powder into a polymer melt and pelletizing the melt. The expandable polymer particles are preferably produced by means of an extrusion process. Here, the blowing agent is mixed into a polymer melt via an extruder, the sinterable metal powder is mixed in and the polymer melt is pushed through a die plate and pelletized to give particles. The melt is usually cooled after introduction of the blowing agent. Each of these steps can be carried out by means of the apparatuses or apparatus combinations known in plastics processing. The polymer melt can be taken directly from a polymerization reactor or be produced in the mixing extruder or a separate melting extruder by melting of polymer pellets. Static or dynamic mixers are suitable for mixing in the blowing agent and the sinterable metal powder. Cooling of the melt can be carried out in the mixing apparatuses or in separate coolers. Possible pelletization methods are, for example, pressurized underwater pelletization, pelletization using rotating knives and cooling by spray misting of cooling liquids or pelletization by atomization.
- The sinterable metal powder is appropriately mixed in via a side extruder. For example, a substream of the melt stream initially obtained can be branched off via a melt valve into a side stream before passage through the die plate. The metal powder is added to the side stream and mixed homogeneously into the melt stream. Finally, the main stream and the additive-comprising side stream are mixed and discharged via the die plate. To be able to meter the metal powder with sufficient accuracy into the melt stream, the powder can be pasted beforehand. This means that it is incorporated into a liquid which is compatible with the melt and the metal powder so as to form a paste having a preferably high viscosity.
- A suitable process is described, for example, in DE 10 358 786 A1, which is hereby fully incorporated by reference.
- If temperatures above the flash point of the metal powder are reached during production of the expandable polymer particles, a suitable protective gas such as nitrogen or argon is preferably passed through the apparatuses.
- As an alternative, pellets can firstly be produced by mixing a sinterable metal powder into a polymer melt and pelletizing the melt. These pellets can then be reshaped into beads in aqueous suspension in heated and stirred pressure vessels at temperatures in the vicinity of the softening point and at the same time impregnated with blowing agent. This conversion into beads gives bead-shaped particles having a defined particle size. The conversion into beads is generally carried out at from 120 to 160° C., e.g. about 140° C., over a period of from 1 to 24 hours, e.g. from 12 to 16 hours. Suitable processes are described, for example, in DE-A 25 34 833, DE-A 26 21 448, EP-A 53 333 and EP-6 95 109, which are fully incorporated by reference.
- As an alternative, the pellets can be impregnated with blowing agent under superatmospheric pressure at a temperature below the softening temperature of the polymer. A pressure of from 25 to 70 bar (absolute), e.g. about 50 bar, is suitable for this purpose. The temperature can be, for example, from 25 to 60° C., e.g. about 40° C. A time of from 0.5 to 20 hours, e.g. about 8 hours, is generally suitable. For this purpose, a pressure-rated apparatus, e.g. an autoclave, is charged with the pellets, the blowing agent is added in such an amount that it preferably completely covers the pellets and the apparatus is closed. Air is displaced by an inert gas such as nitrogen. The apparatus is then heated and the desired pressure is set. The pressure is established as autogenous pressure of the blowing agent at the treatment temperature or is set by injection of inert gas.
- As sinterable metal powders, mention may be made of, for example, aluminum, iron, in particular iron carbonyl powder, cobalt, copper, nickel, silicon, titanium and tungsten, among which aluminum, iron, copper, nickel and titanium are preferred. As pulverulent metal alloys, mention may be made by way of example of high- or low-alloy steels and also metal alloys based on aluminum, iron, titanium, copper, nickel, cobalt or tungsten. Here, it is possible to use either powders of finished alloys or powder mixtures of the individual alloy constituents. The metal powders, metal alloy powders and metal carbonyl powders can also be used in admixture. When mixed metal powders are used, the melting points of the components of the mixture should not differ too much from one another, since otherwise the lower-melting component flows and the higher-melting component remains. The maximum melting point difference is preferably 800° C. or less, in particular 500° C. or less and most preferably 300° C. or less.
- Suitable metal powders are, for example, atomized metal powders which have been obtained by spraying of liquid metal with compressed gases.
- Carbonyl iron powder is preferred as metal powder. Carbon iron powder is an iron powder which is produced by thermal decomposition of iron carbonyl compounds. To maintain flowability and to prevent agglomeration, it can, for example, be coated with SiO2. Iron phosphide powder can preferably be concomitantly used as corrosion inhibitor. Carbonyl iron powder has a small and uniform particle size; the particles have an essentially spherical shape. The melt viscosity of the composites with polymers is therefore very low and the melting point is uniform. Suitable carbonyl iron powders are described, for example, in DE 10 2005 062 028.
- Further preferred metal powders are powders composed of aluminum and copper.
- The particle sizes of the powders are preferably from 0.1 to 80 μm, particularly preferably from 1.0 to 50 μm.
- Suitable polymers are thermoplastic polymers having a good uptake capacity for blowing agent, for example styrene polymers, polyamides (PA), polyolefins such as polypropylene (PP), polyethylene (PE) or polyethylene-propylene copolymers, polyacrylates such as polymethyl methacrylate (PMMA), polycarbonate (PC), polyesters such as polyethylene terephthalate (PET) or polybutylene terephthalate (PBT), polyether sulfones (PES), polyether ketones or polyether sulfides (PES) or mixtures thereof. Particular preference is given to using styrene polymers.
- As styrene polymers, preference is given to using clear, colorless polystyrene (GPPS), high-impact polystyrene (HIPS), anionically polymerized polystyrene or high-impact polystyrene (A-IPS), styrene-α-methstyrene copolymers, acrylonitrile-butadiene-styrene polymers (ABS), styrene-acrylonitrile (SAN), acrylonitrile-styrene-acrylic ester (ASA), methyl acrylate-butadiene-styrene (MBS), methyl methacrylate-acrylonitrile-butadiene-styrene (MABS) polymers or mixtures thereof or with polyphenylene ether (PPE).
- To achieve better dispersion of the particles in the polymer melt, dispersants can optionally be added. Examples are oligomeric polyethylene oxide having an average molecular weight from 200 to 600, stearic acid, stearamide, hydroxystearic acid, magnesium, calcium or zinc stearate, fatty alcohols, ethoxylated fatty alcohols, fatty alcohol sulfonates, ethoxylated glycerides and block copolymers of ethylene oxide and propylene oxide, and also polyisobutylene.
- The polymer is driven off by means of a heat treatment. The sinterable metal powder is sintered to give a porous sintered shaped body. The term “drive off” comprises upstream decomposition and/or pyrolysis steps. The heat treatment can be carried out in a single-stage or multistage process. Preference is given to driving off the polymer (binder removal) at a first temperature in a first step and sintering the resulting binder-free shaped body at a second temperature. The second temperature is generally at least 100° C. higher than the first temperature. If the shaped body is exposed directly to the sintering temperature, severe soot formation on the shaped metal body is frequently observed, presumably due to excessively rapid pyrolysis.
- Binder removal and the sintering process can be carried out in the same apparatus; however, different apparatuses can also be used. Suitable furnaces for carrying out binder removal and/or sintering are convection box furnaces, shaft retort furnaces, convection shuttle kilns, hood-type furnaces, elevator furnaces, muffle furnaces and tube furnaces. Belt furnaces, combi-chamber furnaces or shuttle kilns are suitable for carrying out the steps of binder removal and sintering in the same apparatus. The furnaces can be provided with facilities for setting a defined binder removal atmosphere and/or sintering atmosphere.
- To carry out binder removal, the shaped body is preferably exposed suddenly to the binder removal temperature and not heated slowly to the binder removal temperature, since otherwise the polymer can run and the foam structure can be lost. It is thus generally not a good idea to leave the shaped body in the heating zone of the furnace during the heating phase. To carry out binder removal in the laboratory, it is possible to use, for example, a tube furnace having a long interior tube and to position the specimen in the tube but outside the heating zone during the heating phase. As soon as the target temperature has been reached, the specimen can be pushed into the heating zone. Binder removal can be carried out industrially using, for example, belt furnaces in particular.
- Binder removal is preferably carried out in a defined atmosphere. In general, preference is given to an inert atmosphere or reducing atmosphere, with a reducing atmosphere being particularly preferred. In the case of metals such as aluminum, zinc or copper, it can be advantageous to carry out binder removal under slightly oxidizing conditions in order to increase the green strength. Better removal of residual carbon and a strength-increasing oxide skin on the surface of the metal powder particles are achieved in this way.
- A temperature of from 150 to 800° C. is generally suitable for binder removal. In the case of iron, a temperature of about 700° C. has been found to be useful, and a temperature of from 400 to 600° C. has been found to be useful in the case of aluminum. The duration depends greatly on the size of the shaped bodies.
- Binder removal is followed by a sintering process. This sintering process can be carried out at a temperature of from 250 to 1500° C. In the case of iron, a sintering temperature of from 900 to 1100° C. has been found to be useful, and a temperature of not more than 650° C. has been found to be useful in the case of aluminum. The sintering atmosphere can be matched to the metal used. In general, an inert atmosphere or reducing atmosphere is preferred, with a reducing atmosphere being particularly preferred.
- As reducing atmosphere during binder removal and/or sintering, hydrogen or mixtures of hydrogen and inert gas, e.g. a hydrogen/nitrogen mixture, have been found to be useful. The mixture of hydrogen and inert gas preferably comprises at least 3% by volume of hydrogen.
- The shaped body can sometimes undergo “after-foaming” during pyrolysis. It can be advantageous to carry out the pyrolysis in a mold having perforated walls, with greater filling of the mold and also compaction and conglutination taking place.
- High-strength porous metallic light-weight bodies are achieved according to the invention.
- The invention is illustrated by the following examples.
- a) Extrusion of polystyrene with carbonyl iron powder:
- 4.0 kg of polystyrene (obtainable under the designation 158K from BASF SE, Ludwigshafen, Germany) were compounded with 16 kg of carbonyl iron powder (carbonyl iron powder EQ, obtainable from BASF SE) in an extruder and the melt was pelletized by die-face pelletization to give pellets having an average particle size of about 3 mm.
- b) Pressure impregnation with pentane:
- The pellets were then immersed in pentane S (80% of n-pentane, 20% of isopentane) and maintained at a pressure of 50 bar and a temperature of 40° C. in a pressure autoclave for 4 hours. This gave polymer particles loaded with about 5% by weight of pentane.
- c) Production of the green body:
- The pellets were introduced into a closed cube-shaped steel mold having an edge length of 4 cm and the mold was heated to about 100° C. by means of steam for 10 minutes. The polymer particles expanded during this treatment and fused to give a green body which was taken from the mold.
- d) Binder removal and sintering:
- The green body was sawn into smaller cubes by means of a saw and subsequently placed in a porcelain boat in a fused silica tube. The fused silica tube was installed horizontally in a hinged high-temperature tube furnace (model LOBA 11-50 from HTM Reetz, Berlin, Germany). The fused silica tube projected out of the furnace at both ends. The porcelain boat was firstly placed in an outer end of the fused silica tube, i.e. outside the heating zone. Nitrogen was passed through the fused silica tube.
- The furnace was set to 700° C. As soon as the furnace reached a temperature of 700° C., the nitrogen flow was reduced by 50% from 20 l/h to 10 l/h and supplemented by a hydrogen flow of 10 l/h. The porcelain boat was subsequently pushed inside the fused silica tube into the middle of the furnace. After the specimen had reached a temperature of 700° C., it was left in the heating zone for 10 minutes. It was then pulled from the heating zone again to the end of the fused silica tube.
- The furnace was then set to 900° C. As soon as the set temperature had been reached, the porcelain boat was pushed back into the middle of the furnace. After a sintering temperature of 900° C. had been reached, the specimen was left in the heating zone for 15 minutes. The porcelain boat was then pulled out of the heating zone again and the furnace was switched off. After cooling, the specimen was taken out.
- e) Examination of the mechanical properties:
- The examination of the mechanical properties was carried out by a method based on the test standard DIN EN 826—compressive strength of insulation materials. Here, the compressive stress at 10-100% deformation and also the E modulus can be determined. Specimens having the same composition which had all been subjected to binder removal at 700° C. for 10 minutes but had been sintered at different temperatures (900° C. and 1000° C.) for different residence times were examined.
- The following results were obtained:
-
Compres- Binder sive stress re- Sin- at 10% moval tering Max. defor- E Exper- [° C./ [° C./ Density stress mation modulus iment min] min] (g/cm3) (kPa) (kPa) (kPa) 1 700/10 900/5 1.27 4187 2527 370285 2 700/10 900/10 1.43 6180 3397 452462 3 700/10 900/15 1.64 10654 6799 668253 4 700/10 900/30 1.59 11 746 9033 1 211 838 5 700/10 900/60 2.29 14 794 12 247 2 633 667 6 700/10 1000/15 2.39 21 709 18 883 4 777 498 7 700/10 900/30 1.98 20 179 17 348 3 608 267 1000/5 8 700/10 900/15 2.28 26 571 19 246 5 103 210 1000/15 - Kneading of polystyrene with carbonyl iron powder:
- 70 g of polystyrene 158K (from BASF SE, Ludwigshafen, Germany) were melted in a kneader (model Messkneter H60 from IKA Staufen, Germany). 280 g of carbonyl iron powder EQ were subsequently added a little at a time. The mixture was subsequently kneaded for 30 minutes. After kneading, the product was discharged and roughly pelletized. The coarse pellets were subsequently milled to an average diameter of about 5 mm in a mill. The further steps were carried out in a manner analogous to example 1.
- Kneading of polystyrene with aluminum:
- 200 g of polystyrene 158K (from BASF, Ludwigshafen, Germany) were melted in a kneader (from Linden, Marienheide, Germany). 622 g of coarse aluminum powder ASMEP123 CL (from ECKA, Fürth, Germany) were subsequently added a little at a time and the mixture was subsequently kneaded for 30 minutes. After kneading, the product was discharged and roughly pelletized. The coarse pellets were subsequently milled to an average diameter of about 5 mm in a mill. The further steps were carried out in a manner analogous to example 1, with binder removal and sintering being carried out in one step at 600° C. over a period of 5 minutes.
- Kneading of polystyrene with copper
- 200 g of polystyrene 158K (from BASF, Ludwigshafen, Germany) were melted in a kneader (from Linden, Marienheide, Germany). 910 g of copper Rogal GK 0/50 (from ECKA, Fürth, Germany) were subsequently added a little at a time and the mixture was subsequently kneaded for 30 minutes. After kneading, the product was discharged and roughly pelletized. The coarse pellets were subsequently milled to an average diameter of about 5 mm in a mill. The further steps were carried out in a manner analogous to example 1, with binder removal being carried out at 700° C. over a period of 5 minutes and sintering being carried out at 850° C. over a period of 10 minutes.
Claims (15)
1-14. (canceled)
15. A process for producing porous sintered shaped metal bodies, wherein expandable polymer particles in which a sinterable metal powder is dispersed are foamed to form a shaped body and the shaped body is subjected to a heat treatment in which the polymer is driven off and the sinterable metal powder sinters to give a porous sintered shaped metal body.
16. The process according to claim 15 , wherein the expandable polymer particles are introduced into a mold and foamed.
17. The process according to claim 16 , wherein the expandable polymer particles are prefoamed before introduction into the mold.
18. The process according to claim 15 , wherein the proportion by weight of the dispersed sinterable metal powder, based on the total weight of polymer and sinterable metal powder, is from 60 to 95% by weight.
19. The process according to claim 15 , wherein the expandable polymer particles comprise a physical blowing agent.
20. The process according to claim 19 , wherein the expandable polymer particles are obtained by impregnating polymer particles in which the sinterable metal powder is dispersed with a blowing agent.
21. The process according to claim 19 , wherein the blowing agent is an aliphatic hydrocarbon or a halogenated hydrocarbon.
22. The process according to claim 21 , wherein the blowing agent is pentane.
23. The process according to claim 15 , wherein the polymer is a polymer or copolymer of styrene.
24. The process according to claim 15 , wherein the sinterable metal powder has an average particle size of from 0.1 to 80 μm
25. The process according to claim 15 , wherein the sinterable metal powder is aluminum, iron, copper, nickel or titanium.
26. The process according to claim 15 , wherein the sinterable metal powder is carbonyl iron powder.
27. The process according to claim 15 , wherein the expandable polymer particles are essentially spherical.
28. The process according to claim 15 , wherein the expandable polymer particles have a diameter of from 0.5 to 30 mm
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
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EP09161664.9 | 2009-06-02 | ||
EP09161664 | 2009-06-02 | ||
PCT/EP2010/057618 WO2010139686A1 (en) | 2009-06-02 | 2010-06-01 | Method for producing porous metal sintered molded bodies |
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US20120087823A1 true US20120087823A1 (en) | 2012-04-12 |
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US13/375,315 Abandoned US20120087823A1 (en) | 2009-06-02 | 2010-06-01 | Method for producing porous metal sintered molded bodies |
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US (1) | US20120087823A1 (en) |
EP (1) | EP2437905B1 (en) |
JP (1) | JP5763055B2 (en) |
KR (1) | KR20120087810A (en) |
CN (1) | CN102802845B (en) |
ES (1) | ES2498766T3 (en) |
WO (1) | WO2010139686A1 (en) |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US8636929B2 (en) | 2010-05-21 | 2014-01-28 | Basf Se | Nanoporous foamed active compound-containing preparations based on pharmaceutically acceptable thermoplastically workable polymers |
US9080259B2 (en) | 2009-06-30 | 2015-07-14 | Basf Se | Polyamide fibers with dyeable particles and production thereof |
WO2018200515A1 (en) * | 2017-04-24 | 2018-11-01 | Markforged, Inc. | Sintering additively manufactured parts in microwave oven |
US10377083B2 (en) | 2016-12-02 | 2019-08-13 | Markforged, Inc. | Supports for sintering additively manufactured parts |
US10464131B2 (en) | 2016-12-02 | 2019-11-05 | Markforged, Inc. | Rapid debinding via internal fluid channels |
US10800108B2 (en) | 2016-12-02 | 2020-10-13 | Markforged, Inc. | Sinterable separation material in additive manufacturing |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
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CN106077651A (en) | 2016-05-11 | 2016-11-09 | 宁海县大雅精密机械有限公司 | The part preparation method of built-in pore passage structure |
CN107641729B (en) * | 2017-09-29 | 2019-12-10 | 泰州亿丰达电器有限公司 | method for preparing foam metal material by liquid polymer auxiliary foaming |
CN108342604B (en) * | 2018-02-27 | 2019-11-12 | 西安佰优智能科技有限责任公司 | A kind of preparation method of closed-cell foam metal |
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US20010016610A1 (en) * | 2000-01-25 | 2001-08-23 | Basf Aktiengesellschaft | Expandable olefin bead polymers |
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US5976454A (en) * | 1996-04-01 | 1999-11-02 | Basf Aktiengesellschaft | Process for producing open-celled, inorganic sintered foam products |
AT6727U1 (en) * | 2003-01-30 | 2004-03-25 | Plansee Ag | METHOD FOR PRODUCING POROUS SINTERED BODIES |
WO2008050753A1 (en) * | 2006-10-23 | 2008-05-02 | Mitsubishi Materials Corporation | Apparatus for producing porous body and method for producing porous body |
-
2010
- 2010-06-01 US US13/375,315 patent/US20120087823A1/en not_active Abandoned
- 2010-06-01 WO PCT/EP2010/057618 patent/WO2010139686A1/en active Application Filing
- 2010-06-01 KR KR1020117031251A patent/KR20120087810A/en not_active Application Discontinuation
- 2010-06-01 CN CN201080024386.XA patent/CN102802845B/en not_active Expired - Fee Related
- 2010-06-01 ES ES10724437.8T patent/ES2498766T3/en active Active
- 2010-06-01 EP EP10724437.8A patent/EP2437905B1/en not_active Not-in-force
- 2010-06-01 JP JP2012513595A patent/JP5763055B2/en not_active Expired - Fee Related
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Publication number | Priority date | Publication date | Assignee | Title |
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US20010016610A1 (en) * | 2000-01-25 | 2001-08-23 | Basf Aktiengesellschaft | Expandable olefin bead polymers |
Cited By (14)
Publication number | Priority date | Publication date | Assignee | Title |
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US9080259B2 (en) | 2009-06-30 | 2015-07-14 | Basf Se | Polyamide fibers with dyeable particles and production thereof |
US8636929B2 (en) | 2010-05-21 | 2014-01-28 | Basf Se | Nanoporous foamed active compound-containing preparations based on pharmaceutically acceptable thermoplastically workable polymers |
US10800108B2 (en) | 2016-12-02 | 2020-10-13 | Markforged, Inc. | Sinterable separation material in additive manufacturing |
US10377083B2 (en) | 2016-12-02 | 2019-08-13 | Markforged, Inc. | Supports for sintering additively manufactured parts |
US10377082B2 (en) | 2016-12-02 | 2019-08-13 | Markforged, Inc. | Supports for sintering additively manufactured parts |
US10391714B2 (en) | 2016-12-02 | 2019-08-27 | Markforged, Inc. | Supports for sintering additively manufactured parts |
US10464131B2 (en) | 2016-12-02 | 2019-11-05 | Markforged, Inc. | Rapid debinding via internal fluid channels |
US10556384B2 (en) | 2016-12-02 | 2020-02-11 | Markforged, Inc. | Supports for sintering additively manufactured parts |
US11173550B2 (en) | 2016-12-02 | 2021-11-16 | Markforged, Inc. | Supports for sintering additively manufactured parts |
US10828698B2 (en) | 2016-12-06 | 2020-11-10 | Markforged, Inc. | Additive manufacturing with heat-flexed material feeding |
WO2018200512A1 (en) * | 2017-04-24 | 2018-11-01 | Markforged, Inc. | Sintering additively manufactured parts in microwave oven |
WO2018200515A1 (en) * | 2017-04-24 | 2018-11-01 | Markforged, Inc. | Sintering additively manufactured parts in microwave oven |
EP3615253A4 (en) * | 2017-04-24 | 2021-02-24 | Markforged, Inc. | Sintering additively manufactured parts in microwave oven |
EP3615250A4 (en) * | 2017-04-24 | 2021-02-24 | Markforged, Inc. | Sintering additively manufactured parts in microwave oven |
Also Published As
Publication number | Publication date |
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CN102802845B (en) | 2015-08-12 |
KR20120087810A (en) | 2012-08-07 |
JP5763055B2 (en) | 2015-08-12 |
ES2498766T3 (en) | 2014-09-25 |
EP2437905B1 (en) | 2014-07-02 |
WO2010139686A1 (en) | 2010-12-09 |
CN102802845A (en) | 2012-11-28 |
JP2012528939A (en) | 2012-11-15 |
EP2437905A1 (en) | 2012-04-11 |
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Owner name: BASF SE, GERMANY Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:JOSHI, KETAN;BELLIN, INGO;SANDLER, JAN KURT WALTER;AND OTHERS;SIGNING DATES FROM 20100617 TO 20100726;REEL/FRAME:027299/0629 |
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