Method for producing spherical thermoplastic polymer particles

Patent metadata

Field	Value
Publication number	US-11897169-B2
Application number	US-202017596628-A
Country	US
Kind code	B2
Filing date	Jun 18, 2020
Priority date	Jun 18, 2019
Publication date	Feb 13, 2024
Grant date	Feb 13, 2024

Abstract

A process for producing particles of a thermoplastic polymer in spherical form involves providing at least one thermoplastic polymer in a molten state and providing an aqueous solution of at least one surface-active substance. The aqueous solution is in a temperature range from 100 to 300° C. The process also involves dispersing the thermoplastic polymer in the aqueous solution to obtain an aqueous solution containing dispersed thermoplastic polymer, which is cooled down to a temperature below the solidification point of the thermoplastic polymer to obtain a suspension containing an aqueous solution and particles of the thermoplastic polymer suspended in a solid state and in spherical form. The particles can be separated from the suspension and, optionally, dried. The particles obtained from the process have a particle size distribution having a d[4,3] value of more than 10 μm and a d90.3 value of more than 20 μm.

First claim

The invention claimed is:

1. A process for producing particles of a thermoplastic polymer in spherical form, the process comprising:
(i) providing at least one thermoplastic polymer in a molten state;
(ii) providing an aqueous solution of at least one surface-active substance, wherein the aqueous solution of the at least one surface-active substance is at a temperature in a range from 100 to 300° C.;
(iii) dispersing the at least one thermoplastic polymer from (i) in the aqueous solution of the at least one surface-active substance from (ii), to obtain an aqueous solution comprising dispersed thermoplastic polymer;
(iv) cooling down the aqueous solution comprising dispersed thermoplastic polymer to a temperature below a solidification point of the at least one thermoplastic polymer, to obtain a suspension comprising an aqueous solution and particles of the at least one thermoplastic polymer suspended therein in a solid state, wherein the particles are in spherical form;
(v) separating the particles of the at least one thermoplastic polymer in spherical form from the suspension obtained in (iv); and
(vi) optionally, drying the particles of the at least one thermoplastic polymer in spherical form that have been separated off in (v);
wherein the particles of the at least one thermoplastic polymer in spherical form that have been separated off in (v) and optionally dried in (vi) have a particle size distribution having a d[4,3] value of more than 10 μm and a d 90.3 value of more than 20 μm.

2. The process according to claim 1 , wherein (i) comprises:
(i.1) providing the at least one thermoplastic polymer in a solid state; and
(i.2) melting the at least one thermoplastic polymer to obtain the at least one thermoplastic polymer in the molten state.

3. The process according to claim 1 , wherein the at least one thermoplastic polymer in the molten state is dispersed in the aqueous solution of the at least one surface-active substance in (iii) under action of mechanical force, ultrasound, and/or high-pressure homogenization, to obtain the aqueous solution comprising dispersed thermoplastic polymer.

4. The process according to claim 2 , wherein the melting in (i.2) is effected in an extruder or by means of extrusion.

5. The process according to claim 1 , wherein the dispersing in (iii) is effected at a temperature in a range from 100 to 300° C.

6. The process according to claim 1 , wherein the cooling in (iv) is effected to a temperature in a range from 20 to 100° C.

7. The process according to claim 1 , wherein the particles of the at least one thermoplastic polymer in spherical form that are separated off in (v) and optionally dried in (vi) have a particle size distribution having a d[4,3] value of more than 20 μm.

8. The process according to claim 1 , wherein the particles of the at least one thermoplastic polymer in spherical form that are separated off in (v) and optionally dried in (vi) have a particle size distribution having a d 50.3 value of more than 20 μm.

9. The process according to claim 1 , wherein the at least one thermoplastic polymer is selected from the group consisting of polyurethane, polyester, polyetherester, polyesterester, polyamide, polypropylene, polyetheramide, polybutadiene-styrene, and ethylene-vinyl acetate.

10. The process according to claim 1 , wherein the at least one surface-active substance is selected from the group consisting of polyvinylalcohols.

11. The process according to claim 1 , wherein the at least one surface-active substance is present in an amount in a range from 0.1% to 20% by weight, based on a total weight of the aqueous solution of the at least one surface-active substance from (ii).

12. The process according to claim 1 , wherein the spherical form of the particles of the at least one thermoplastic polymer is a sphere or an ellipsoid.

13. The process according to claim 7 , wherein the particles of the at least one thermoplastic polymer in spherical form that are separated off in (v) and optionally dried in (vi) have a particle size distribution having a d 90.3 value of more than 50 μm.

14. The process according to claim 9 , wherein the at least one thermoplastic polymer comprises a thermoplastic polyurethane (TPU).

15. The process according to claim 10 , wherein the at least one surface-active substance is selected from the group consisting of at least partly hydrolysed polyvinylacetates.

Assignees

• Basf Se

Inventors

• Bauder Andreas
• Muelheims Kerstin
• Freese Michael
• Stammer Achim

Classifications

• B29B9/10 Primary

  by moulding the material, i.e. treating it in the molten state · CPC title

• B29B9/12

  characterised by structure or composition · CPC title

• B29C48/36

  Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die · CPC title

• B29C64/153

  using layers of powder being selectively joined, e.g. by selective laser sintering or melting · CPC title

• B33Y10/00

  Processes of additive manufacturing · CPC title