BINDER-COMPRISING THERMOPLASTIC COMPOSITIONS FOR PRODUCING SHAPED METALLIC BODIES

• US 20090288739A1
• Filed: 07/05/2007
• Published: 11/26/2009
• Est. Priority Date: 07/13/2006
• Status: Abandoned Application

• Current Assignee: BASF SE
• Original Assignee: BASF SE
• Inventors: Wohlfromm, Hans, Hendrik ter Maat, Johan Herman, Blömacher, Martin, Assmann, Jens
• Application Number:
  US12/373,439
• Publication Number:
  US 20090288739A1
• Time in Patent Office: Days
• US Class Current: 148/522
• CPC Class Codes: B22F 1/10 Metallic powder containing lubricating or binding agents; Metallic powder containing organic material
• CPC Class Codes: B22F 2998/10 Processes characterised by the sequence of their steps
• CPC Class Codes: B22F 3/1025 not by heating only
• CPC Class Codes: C04B 2235/5436 micrometer sized, i.e. from 1 to 100 micron
• CPC Class Codes: C04B 35/632 Organic additives
• CPC Class Codes: C04B 35/63408 Polyalkenes
• CPC Class Codes: C04B 35/63488 Polyethers, e.g. alkylphenol polyglycolether, polyethylene glycol [PEG], polyethylene oxide [PEO]
• CPC Class Codes: C08L 23/00 Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
• CPC Class Codes: C08L 2666/02 Organic macromolecular compounds, natural resins, waxes or and bituminous materials
• CPC Class Codes: C08L 2666/06 Homopolymers or copolymers of unsaturated hydrocarbons; Derivatives thereof
• CPC Class Codes: C08L 2666/22 Macromolecular compounds not provided for in C08L2666/16 - C08L2666/20
• CPC Class Codes: C08L 59/00 Compositions of polyacetals; Compositions of derivatives of polyacetals of polyvinyl acetals C08L29/14
• CPC Class Codes: C08L 71/02 Polyalkylene oxides

Abstract

The present invention relates to binders for pulverulent metals or pulverulent metal alloys, thermoplastic compositions comprising these binders for producing shaped metallic bodies, a process for producing them, their use and a process for producing shaped bodies therefrom.

Claims

1. A binder B) for pulverulent metals or metal alloys or mixtures thereof, which comprises

B₁) from 50 to 96% by weight of one or more polyoxymethylene homopolymers or copolymers;

B₂) from 2 to 35% by weight of one or more polyolefins;

B₃) from 2 to 40% by weight of poly-1,3-dioxepane or poly-1,3-dioxolane or mixtures thereof,

where the proportions by weight of the components B₁, B₂ and B₃ add up to 100%.

2. The binder according to claim 1, wherein the mixture comprises from 70 to 85% by weight of the component B₁), from 4 to 15% by weight of the component B₂), and from 10 to 26% by weight of the component B₃), where the proportions by weight of the components B₁, B₂ and B₃ add up to 100%.

3. The binder according to claim 1, wherein a polyoxymethylene copolymer comprising from 0.01 to 20 mol % of 1,3-dioxepane or 1,3-dioxolane as comonomer is present as component B₁), polyethylene is present as component B₂) and poly-1,3-dioxepane or poly-1,3-dioxolane is present as component B₃).

11. The binder according to claim 2, wherein a polyoxymethylene copolymer comprising from 0.01 to 20 mol % of 1,3-dioxepane or 1,3-dioxolane as comonomer is present as component B₁), polyethylene is present as component B₂) and poly-1,3-dioxepane or poly-1,3-dioxolane is present as component B₃).

4. A thermoplastic composition for producing shaped metallic bodies, which comprises

A) from 40 to 70% by volume of a sinterable pulverulent metal or a sinterable pulverulent metal alloy or mixtures thereof,

B) from 30 to 60% by volume of a mixture of

B₁) from 50 to 96% by weight of one or more polyoxymethylene homopolymers or copolymers;

B₂) from 2 to 35% by weight of one or more polyolefins;

B₃) from 2 to 40% by weight of poly-1,3-dioxepane or poly-1,3-dioxolane or mixtures thereof

as binder, where the proportions by weight of the components B₁, B₂ and B₃ add up to 100%, and

C) from 0 to 5% by volume of a dispersant.

5. The thermoplastic composition according to claim 4, wherein the component B) comprises from 70 to 85% by weight of the component B₁), from 4 to 15% by weight of the component B₂), and from 10 to 26% by weight of the component B₃), where the proportions by weight of the components B₁, B₂ and B₃ add up to 100%.

6. The thermoplastic composition according to claim 4, wherein a polyoxymethylene copolymer comprising from 0.01 to 20 mol % of 1,3-dioxepane as comonomer is present as component B₁), polyethylene is present as component B₂) and poly-1,3-dioxepane or poly-1,3-dioxolane is present as component B₃).

7. A method of producing shaped metallic bodies comprising melting the thermoplastic composition defined according to claim 4.

8. A shaped metallic body produced from a thermoplastic composition defined according to claim 4.

10. A process for producing shaped bodies from a thermoplastic composition defined according to claim 4 by

a) shaping the thermoplastic composition by injection molding, extrusion or pressing to form a green body,

b) removing the binder by treating the green body with a gaseous acid-comprising atmosphere at a temperature in the range from 20 to 180°

C. for from 0.1 to 24 hours,

c) subsequently heating the green body at a temperature in the range from 250 to 600°

C. for from 0.1 to 12 hours and

d) subsequently sintering the resulting green body which has been freed of binder in this way.

12. The thermoplastic composition according to claim 5, wherein a polyoxymethylene copolymer comprising from 0.01 to 20 mol % of 1,3-dioxepane as comonomer is present as component B₁), polyethylene is present as component B₂) and poly-1,3-dioxepane or poly-1,3-dioxolane is present as component B₃).

13. A method of producing shaped metallic bodies comprising melting the thermoplastic composition defined according to claim 5.

14. A method of producing shaped metallic bodies comprising melting the thermoplastic composition defined according to claim 6.

15. A shaped metallic body produced from a thermoplastic composition defined according to claim 5.

16. A shaped metallic body produced from a thermoplastic composition defined according to claim 6.

17. A process for producing shaped bodies from a thermoplastic composition defined according to claim 5 by

a) shaping the thermoplastic composition by injection molding, extrusion or pressing to form a green body,

b) removing the binder by treating the green body with a gaseous acid-comprising atmosphere at a temperature in the range from 20 to 180°

C. for from 0.1 to 24 hours,

c) subsequently heating the green body at a temperature in the range from 250 to 600°

C. for from 0.1 to 12 hours and

d) subsequently sintering the resulting green body which has been freed of binder in this way.

18. A process for producing shaped bodies from a thermoplastic composition defined according to claim 6 by

a) shaping the thermoplastic composition by injection molding, extrusion or pressing to form a green body,

b) removing the binder by treating the green body with a gaseous acid-comprising atmosphere at a temperature in the range from 20 to 180°

C. for from 0.1 to 24 hours,

c) subsequently heating the green body at a temperature in the range from 250 to 600°

C. for from 0.1 to 12 hours and

d) subsequently sintering the resulting green body which has been freed of binder in this way.

19. The process according to claim 10 wherein the subsequently heating c) takes place for from 0.3 to 6 hours.

20. The process according to claim 17 wherein the subsequently heating c) takes place for from 0.3 to 6 hours.

9. A process for producing a thermoplastic composition comprising as significant components

A) from 40 to 70% by volume of a sinterable pulverulent metal or a sinterable pulverulent metal alloy or mixtures thereof,

B) from 30 to 60% by volume of a mixture of

B₁) from 50 to 96% by weight of one or more polyoxymethylene homopolymers or copolymers;

B₂) from 2 to 35% by weight of one or more polyolefins;

B₃) from 2 to 40% by weight of poly-1,3-dioxepane or poly-1,3-dioxolane or mixtures thereof

as binder, where the proportions by weight of the components B₁, B₂ and B₃ add up to 100%, and

C) from 0 to 5% by volume of a dispersant,

wherein

a₁) the component B) is melted at temperatures of from 150 to 220°

C. and subsequently

b₁) the component A), if appropriate together with the component C), is metered into the melt stream of the component B) at temperatures in the same range as in step a) or

a₂) the components B) and C) are melted in the presence of the component A) at temperatures of from 150 to 220°

C.