PROCESS FOR PRODUCING METALLIC OR CERAMIC SHAPED BODIES

• US 20120235330A1
• Filed: 03/14/2012
• Published: 09/20/2012
• Est. Priority Date: 03/16/2011
• Status: Active Grant

• Current Assignee: BASF SE
• Original Assignee: BASF SE
• Inventors: ter Maat, Johan, Wohlfromm, Hans, Blömacher, Martin
• Granted Patent: US 9,162,927 B2
• Time in Patent Office: Days
• US Class Current: 264/645
• CPC Class Codes: B22F 2201/00 Treatment under specific atmosphere
• CPC Class Codes: B22F 2998/10 Processes characterised by the sequence of their steps
• CPC Class Codes: B22F 2999/00 Aspects linked to processes or compositions used in powder metallurgy
• CPC Class Codes: B22F 3/1021 Removal of binder or filler removal of binder from ceramics C04B35/638
• CPC Class Codes: B22F 3/1025 not by heating only
• CPC Class Codes: B22F 3/225 by injection molding
• CPC Class Codes: B22F 3/227 by organic binder assisted extrusion
• CPC Class Codes: B28B 1/24 by injection moulding injection moulding of ceramic slips B28B1/265; of tubular articles B28B21/38
• CPC Class Codes: C04B 2235/3225 Yttrium oxide or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/5445 submicron sized, i.e. from 0,1 to 1 micron
• CPC Class Codes: C04B 2235/6022 Injection moulding
• CPC Class Codes: C04B 2235/77 Density
• CPC Class Codes: C04B 35/111 Fine ceramics
• CPC Class Codes: C04B 35/26 based on ferrites
• CPC Class Codes: C04B 35/486 Fine ceramics
• CPC Class Codes: C04B 35/505 based on yttrium oxide
• CPC Class Codes: C04B 35/565 based on silicon carbide
• CPC Class Codes: C04B 35/581 based on aluminium nitride
• CPC Class Codes: C04B 35/584 based on silicon nitride
• CPC Class Codes: C04B 35/63408 Polyalkenes
• CPC Class Codes: C04B 35/63424 : Polyacrylates; Polymethacrylates
• CPC Class Codes: C04B 35/63444 : Nitrogen-containing polymers, e.g. polyacrylamides, polyacrylonitriles, polyvinylpyrrolidone [PVP], polyethylenimine [PEI]
• CPC Class Codes: C04B 35/63452 : Polyepoxides
• CPC Class Codes: C04B 35/63456 : Polyurethanes; Polyisocyanates
• CPC Class Codes: C04B 35/63488 : Polyethers, e.g. alkylphenol polyglycolether, polyethylene glycol [PEG], polyethylene oxide [PEO]
• CPC Class Codes: C04B 35/638 : Removal thereof

Abstract

A process for producing a metallic or ceramic shaped body from a thermoplastic material comprising

• • A) 40 to 65% inorganic sinterable powder A
  • B) 35 to 60% binder
    • B₁) 50 to 95% polyoxymethylene homo- or copolymers;
    • B₂) 5 to 50% of a polymer dissolved or dispersed in B₁) with a particle size of less than 1 μm,
    • and
  • C) 0 to 5% by volume of a dispersing aid,
  • by injection molding or extrusion to give a green body, removing the binder and sintering, which comprises removing the binder by
    • a) treating the molding with a solvent which extracts the binder component B₂) from the molding and in which the binder component B₁) is insoluble,
    • b) removing the solvent from the molding by drying, and
    • c) treating the molding in an acid-containing atmosphere
      is described.

Claims

1. A process for producing a metallic or ceramic shaped body from a thermoplastic material comprising

A) 40 to 65% by volume of at least one inorganic sinterable powder A

B) 35 to 60% by volume of a mixture of

B₁) 50 to 95% by weight of one or more polyoxymethylene homo- or copolymers;

B₂) 5 to 50% by weight of a polymer homogeneously dissolved in B₁) or dispersed in B₁) with a mean particle size of less than 1 μ

m,

as a binder, and

C) 0 to 5% by volume of a dispersing aid,

where the sum of components A), B) and C) adds up to 100% by volume,

by injection molding or extrusion to give a green body, removing the binder and sintering, which comprises removing the binder by

a) treating the molding with a solvent which extracts the binder component B₂) from the molding and in which the binder component B₁) is insoluble,

b) then removing the solvent from the molding by drying, and

c) then treating the molding in an acid-containing atmosphere which removes the binder component B₁ from the molding.

2. The process according to claim 1, wherein acids which are solid at room temperature and sublime or melt and evaporate at higher temperatures are used in step c).

3. The process according to claim 1, wherein an anhydrous oxalic acid is used in step c).

4. The process according to claim 1, wherein step a) is conducted at a temperature above RT up to the boiling temperature of the solvent.

5. The process according to claim 1, wherein the inorganic sinterable powder A) used is a reactive and/or oxidation-sensitive powder.

6. The process according to claim 1, wherein the proportion of the binder component B₂) is 10 to 30% by weight.

7. The process according to claim 1, wherein the binder component B₂) is selected from the group comprising:

polyolefins, aliphatic polyurethanes, aliphatic uncrosslinked polyepoxides, polyethers, aliphatic polyamides and polyacrylates, and mixtures thereof.

8. The process according to claim 1, wherein the binder component B₂) is a polyether selected from the group comprising polyethylene oxide, polypropylene oxide, poly-1,3-dioxepane, poly-1,3-dioxane, poly-1,3-dioxolane, polytetrahydrofuran (poly(tetramethylene) oxide) and mixtures thereof.