Process for improving the flexural toughness of moldings

Patent metadata

Field	Value
Publication number	US-10961384-B2
Application number	US-201515312361-A
Country	US
Kind code	B2
Filing date	May 20, 2015
Priority date	May 21, 2014
Publication date	Mar 30, 2021
Grant date	Mar 30, 2021

Abstract

Poly-1,3-dioxepane, poly-1,3-dioxolane, polytetrahydrofurane or mixtures thereof are used in molding materials comprising polyoxymethylene or a copolymer containing a majority of oxymethylene units, for improving the flexural toughness of moldings formed from the molding materials.

First claim

The invention claimed is:

1. A process for improving the flexural toughness of moldings formed from a molding material comprising:
incorporating poly-1,3-dioxepane, poly-1,3-dioxolane, polytetrahydrofurane or mixtures thereof into the molding material; and
forming a molding from the molding material, wherein the molding has increased elongation at break compared to a molding without the poly-1,3-dioxepane, poly-1,3-dioxolane, polytetrahydrofurane, or mixture thereof;
the molding material comprising:
an oxymethylene polymer mixture comprising:
(B1.1). from 10 to 90% by weight of a polyoxymethylene homopolymer or a copolymer containing a majority of oxymethylene units, with a weight-average molar mass (Mw) in the range from above 60,000 to 200,000 g/mol, and
(B1.2). from 10 to 90% by weight of a copolymer containing a majority of oxymethylene units, with a weight-average molar mass (Mw) in the range of 10,000 to 60,000 g/mol; and

40 to 70% by volume of sinterable pulverant metal, sinterable pulverant metal alloy, sinterable pulverant ceramic powders or mixtures thereof, based on the molding material;
wherein, the copolymer in B1.2 is a polyoxymethylene copolymer, at least 90% by weight of which, based on the copolymer, is derived from trioxane and 1,3-dioxepane as monomers and butylal as regulator, with a proportion of 1,3-dioxepane, based on the copolymer, in the range from 1 to 30% by weight, and a proportion of butylal, based on the copolymer, in the range from 0.01 to 2.5% by weight, the % by weight being based on the copolymer and the molecular weights are determined by gel permeation chromatography or size exclusion chromatography;
and, if B1.1 is a copolymer containing a majority of oxymethylene units, the copolymer in B1.1 is a polyoxymethylene copolymer, at least 90% by weight of which, based on the copolymer, is derived from trioxane and 1,3-dioxepane as monomers and butylal as regulator, with a proportion of 1,3-dioxepane, based on the copolymer, in the range from 1 to 30% by weight, and a proportion of butylal, based on the copolymer, in the range from 0.01 to 2.5% by weight, the % by weight being based on the copolymer and the molecular weights are determined by gel permeation chromatography or size exclusion chromatography; and
wherein the copolymer in B1.2 has a polydispersity Mw/Mn in the range from 3 to 5.

2. The process according to claim 1 , wherein the molding has improved elongation at break compared to a molding without the poly-1,3-dioxepane, poly-1,3-dioxolane, polytetrahydrofurane, or mixture thereof.

3. The process according to claim 1 , wherein the poly-1,3-dioxepane, poly-1,3-dioxolane, polytetrahydrofurane or mixtures thereof are employed in an amount, based on the sum of polyoxymethylene or a copolymer containing a majority of oxymethylene units and poly-1,3-dioxepane, poly-1,3-dioxolane, polytetrahydrofurane or mixtures thereof, of from 1 to 16% by weight.

4. The process according to claim 1 , wherein the poly-1,3-dioxepane, poly-1,3-dioxolane, polytetrahydrofurane or mixtures thereof is poly-1,3-dioxepane having a weight-average molecular weight of from 10,000 to 150,000 g/mol.

5. The process according to claim 1 , wherein the weight-average molar mass (M W ) of the polyoxymethylene copolymer (B1.2) is from 30,000 to 60,000 g/mol and/or the number-average molar mass (M n ) is from 5,000 to 18,000 g/mol.

6. The process according to claim 1 , wherein at least 90% by weight of component B1.1, based on the polymer, derive from trioxane and 1,3-dioxepane as monomers, with a proportion of 1,3-dioxepane, based on the polymer, in the range from 1 to 5% by weight.

7. The process according to claim 1 , wherein at least 90% by weight of component B1.2, based on the polymer, derive from trioxane and optionally 1,3-dioxepane as monomers, with a proportion of 1,3-dioxepane, based on the polymer, in the range from 2.7 to 30% by weight.

8. The process according to claim 1 , wherein the molding material after incorporation comprises
A.) from 40 to 70% by volume of the sinterable pulverant metal or metal alloy or ceramic or mixture thereof;
B.) from 30 to 60% by volume of a binder comprising the mixture of:
B1.) from 50 to 97% by weight of the mixture of B1.1 and B1.2, based on the total amount of the component B;
B2.) from 2 to 35% by weight of one or more polyolefins, based on the total amount of component B;
B3.) from 1 to 40% by weight of the poly-1,3-dioxolane, poly-1,3-dioxepane or polytetrahydrofurane or mixtures thereof, based on the total amount of component B, the sum of B1.), B2.) and B3.) adding up to 100% by weight.

9. The process according to claim 1 , wherein the weight-average molar mass (M W ) of the polyoxymethylene copolymer is from 40,000 to 50,000 g/mol and/or the number-average molar mass (M n ) is from 8,000 to 16,000 g/mol.

10. The process according to claim 1 , wherein the number-average molar mass (M n ) of the polyoxymethylene copolymer is from 10,000 to 14,000 g/mol.

11. The process according to claim 5 , wherein the M W /M n ratio of the polyoxymethylene copolymer is in the range from 3.5 to 4.5.

12. The process according to claim 1 , wherein at least 90% by weight of component B1.1, based on the polymer, derive from trioxane and 1,3-dioxepane as monomers, with a proportion of 1,3-dioxepane, based on the polymer, in the range 2 to 3.5% by weight.

13. The process according to claim 1 , wherein at least 90% by weight of component B1.1, based on the polymer, derive from trioxane and 1,3-dioxepane as monomers, with a proportion of 1,3-dioxepane, based on the polymer, in the range from 2.5 to 3% by weight.

14. The process according to claim 1 , wherein at least 90% by weight of component B1.2, based on the polymer, derive from trioxane and 1,3-dioxepane as monomers, with a proportion of 1,3-dioxepane, based on the polymer, in the range from 2.8 to 20% by weight.

15. The process according to claim 1 , wherein at least 90% by weight of component B1.2, based on the polymer, derive from trioxane and 1,3-dioxepane as monomers, with a proportion of 1,3-dioxepane, based on the polymer, in the range from 3 to 17% by weight.

16. The process according to claim 1 , wherein the sinterable pulverant metal, sinterable pulverant metal alloy, sinterable pulverant ceramic powders, or mixture thereof is a stainless steel metal powder.

17. The process according to claim 16 , wherein the stainless steel metal powder has a particle size distribution of D 50 in the range from 10 to 15 μm.

18. The process according to claim 1 , wherein the poly-1,3-dioxepane, poly-1,3-dioxolane, polytetrahydrofurane or mixture thereof is poly-1,3-dioxepane or poly-1,3-dioxolane.

19. The process according to claim 18 , wherein the poly-1,3-dioxepane, poly-1,3-dioxolane, polytetrahydrofurane or mixture thereof is poly 1-3-dioxepane.

20. The process according to claim 19 , wherein the poly-1,3-dioxepane is present in an amount of 9.6-16% by weight, based on the molding material.

21. The process according to claim 20 , wherein poly-1,3-dioxepane, poly-1,3-dioxolane, polytetrahydrofurane or mixtures thereof is a stainless steel metal powder with a particle size distribution of D 50 in the range from 10 to 15 μm.

22. A process for improving the flexural toughness of moldings comprising providing a molding formed from molding materials comprising a mixture comprising from 10 to 90% by weight of a polyoxymethylene homo- or copolymer with a weight-average molar mass (M W ) in the

Assignees

• Basf Se

Inventors

• Von Bernstorff Bernd-Steffen
• Hermant Marie-Claire
• Blömacher Martin

Classifications

• B22F1/103

  containing an organic binding agent comprising a mixture of, or obtained by reaction of, two or more components other than a solvent or a lubricating agent · CPC title

• B22F1/102

  Metallic powder coated with organic material · CPC title

• B22F1/10

  Metallic powder containing lubricating or binding agents; Metallic powder containing organic material · CPC title

• C08L59/04

  Copolyoxymethylenes · CPC title

• C08L59/02 Primary

  Polyacetals containing polyoxymethylene sequences only · CPC title