Microstructured composite particles

Abstract

Microstructured composite particles obtainable by a process in which large particles are bonded to small particles. The composite particles are preferably used as an additive, especially as a polymer additive, as an additive or starting material for the production of components, for applications in medical technology and/or in microtechnology and/or for the production of foamed articles.

Claims

1. A biomedical article, wherein the biomedical article is an implant comprising microstructured composite particles obtained by a process comprising combining large particles with small particles, wherein: the large particles have an average particle diameter in the range from 0.1 m to 10 mm, an average particle diameter of the small particles is not more than 1/10 of the average particle diameter of the large particles, the large particles comprise at least one resorbable polymer, the small particles comprise calcium carbonate, and the small particles form at least one of an arrangement on the surface of the large particles and a non-uniform distribution within the large particles, wherein the small particles comprise precipitated particles of calcium carbonate which have an average particle size in the range from 0.01 m to 1.0 mm.

2. The biomedical article as claimed in claim 1, wherein the large particles comprise at least one thermoplastic polymer.

3. The biomedical article as claimed in claim 1, wherein the large particles comprise at least one resorbable polymer.

4. The biomedical article as claimed in claim 1, wherein the large particles comprise at least one of poly-D-lactic acid, poly-L-lactic acid, and poly-D,L-lactic acid.

5. The biomedical article as claimed in claim 1, wherein the large particles comprise at least one polyamide.

6. The biomedical article as claimed in claim 1, wherein the small particles comprise at least one calcium phosphate.

7. The biomedical article as claimed in claim 6, wherein the small particles comprise Ca.sub.3(PO.sub.4).sub.2, CaHPO.sub.4, Ca(H.sub.2PO.sub.4).sub.2 and/or Ca.sub.5(PO.sub.4).sub.3(OH).

8. The biomedical article as claimed in claim 1, wherein the composite particles comprise a core and a sheath, wherein the core has an average diameter in the range from 0.5 m to 2.0 mm, and wherein the sheath has an average thickness of not more than 20%, based on the core diameter.

9. The biomedical article as claimed in claim 1, wherein the implant comprises the composite particles dispersed in a matrix polymer.

10. The biomedical article as claimed in claim 9, wherein the large particles comprise a biopolymer.

11. The biomedical article as claimed in claim 10, wherein the large particles comprise a resorbable biopolymer.

12. The biomedical article as claimed in claim 11, wherein the implant is in the form of a foam.

13. A biomedical article, wherein the biomedical article is an implant comprising microstructured composite particles obtained by a process comprising combining large particles with small particles, wherein the large particles have an average particle diameter in the range from 0.1 m to 10 mm, an average particle diameter of the small particles is not more than 1/10 of the average particle diameter of the large particles, the large particles comprise at least one polymer, the small particles comprise at least one calcium salt, and the small particles form at least one of an arrangement on the surface of the large particles and a non-uniform distribution within the large particles, wherein the large particles comprise at least one resorbable polyester having a number-average molecular weight in the range from 500 g/mol to 1,000,000 g/mol.

14. The biomedical article as claimed in claim 13, wherein the calcium salt comprises calcium carbonate.

15. The biomedical article as claimed in claim 13, wherein the calcium salt has an aspect ratio below 5.

16. The biomedical article as claimed in claim 14, wherein the calcium salt comprises precipitated calcium carbonate.

17. The biomedical article as claimed in claim 13, wherein the calcium salt comprises sphere-shaped calcium carbonate.

18. The biomedical article as claimed in claim 13, wherein the calcium salt comprises stabilized particles of calcium carbonate, wherein the particles of calcium carbonate comprise at least one substance having a molar mass above 100 g/mol and satisfying the formula RX.sub.n, where the radical R represents a radical comprising at least one carbon atom, the radical X represents a group comprising at least one oxygen atom and at least one carbon atom, sulfur atom, phosphorus atom or nitrogen atom, and n represents a number in the range from 1 to 20.

19. The biomedical article as claimed in claim 13, wherein the weight fraction of calcium salt, based on the overall weight of the composite particles, is not less than 0.1 wt %.

20. The biomedical article as claimed in claim 13, wherein the implant comprises the composite particles dispersed in a matrix polymer.

21. The biomedical article as claimed in claim 20, wherein the implant is in the form of a foam.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIGS. 1a, 1b, and 1c depict the results of an SEM analysis showing a PLA surface substantially covered with sphere-shaped DSACC particles in Example 1;

(2) FIGS. 2a and 2b depict the results of an SEM analysis showing a PLA surface only partly covered with calcium carbonate spheres (spherulites) in Example 2;

(3) FIGS. 3a and 3b depict the results of an SEM analysis showing structured composite particles obtained in Example 3; and,

(4) FIGS. 4a and 4b depict the results of an SEM analysis showing structured composite particles obtained in Example 4.

EXAMPLES

(5) The present invention will now be further illustrated by several examples without any intention of thereby narrowing the inventive concept.

(6) Characterization

(7) The properties of the microstructured composite particles were determined as follows:

(8) Electron Microscope

(9) Scanning electron micrographs were prepared using a high-voltage electron microscope (Zeiss, DSM 962) at 15 kV. The samples were sprayed with a gold-palladium layer.

(10) Thermogravimetric Analysis (TGA)

(11) Thermogravimetric analysis was carried out with a Perkin Elmer STA 6000 under nitrogen (nitrogen flow rate: 20 ml/min) in the range from 40 C. to 1000 C. at a heating rate of 10 C./min.

Example 1

(12) Microstructured composite particles comprising amorphous calcium carbonate and an amorphous polylactide (PLA) were prepared in accordance with the method described in JP 62083029 A by using the NHS 0 apparatus. Cold water at 12 C. was used for cooling. A polylactide pellet material (average particle size 3 mm) was used as mother particles and amorphous calcium carbonate powder (DSACC; average particle size 1 m) was used as the baby particles.

(13) 16 g of polylactide pellet material were mixed with 4 g of CaCO.sub.3 powder and filled at 5000 rpm. The rotor speed of the assembly was adjusted to 16 000 rpm (100 m/s) and the added materials were processed for 1 min. This procedure was repeated with the same quantities of materials and the same machine settings. Altogether 38 g of structured composite particles were obtained.

(14) SEM analysis showed that the PLA surface is substantially covered with the sphere-shaped DSACC particles (see FIG. 1a, 1b, 1c).

Example 2

(15) Microstructured composite particles comprising calcium carbonate spheres (spherulites; SPH) and an amorphous polylactide (PLA) were prepared as described in Example 1 using NHS 0. The same polylactide pellet material as described in Example 1 was used as mother particles, while calcium carbonate spheres (spherulites) having an average particle diameter of 7 m were used as the baby particles.

(16) 16 g of polylactide pellet material were mixed with 4 g of CaCO.sub.3 powder and filled at 5000 rpm. The rotor speed of the assembly was adjusted to 16 000 rpm (100 m/s) and the added materials were processed for 1 min. Altogether 5 repeats were carried out with the same quantities of materials and the same machine settings. Altogether 85 g of structured composite particles were obtained.

(17) The SEM analysis of the structured composite particles obtained is depicted on the following SEM pictures. The PLA surface is only partly covered with the calcium carbonate spheres (spherulites) (see FIG. 2a, 2b).

Example 3

(18) Microstructured composite particles comprising a calcium carbonate of mixed particulate shape (scalenohedra and needles; Schaefer Precarb 400) and a fine powder based on polyamide-12 (PA12) were prepared using NHS 1. Cold water at 12 C. was used for cooling. PA12 (average particle size 50 m) was used as mother particles, while Schaefer Precarb 400 calcium carbonate (average particle size 0.7 m) was used as the baby particles.

(19) 85 g of PA12 powder were mixed with 15 g of Schaefer Precarb 400 CaCO.sub.3 powder and filled at an assembly rotor speed of 4000 rpm (50 m/s). The added materials were processed for 1 min. Altogether 8 repeats were carried out with the same amounts of materials and the same machine settings. Altogether about 760 g of structured composite particles were obtained.

(20) The SEM analysis of the structured composite particles obtained is depicted in FIG. 3a, 3b.

(21) The CaCO.sub.3 content determined using thermogravimetric analysis was 14.4% of PCC.

(22) The particle size distribution of the structured composite particles obtained was determined using laser diffraction (Sympatec, Helos) as d50=48 m.

Example 4

(23) Microstructured composite particles comprising a calcium carbonate of mixed particulate shape (scalenohedra and needles; Schaefer Precarb 400) and a fine powder based on polyamide-12 (PA12) were prepared using NHS 1. Cold water at 12 C. was used for cooling. PA12 (average particle size 50 m) was used as mother particles, while Schaefer Precarb 400 calcium carbonate (average particle size 0.7 m) was used as the baby particles.

(24) 85 g of PA12 powder were mixed with 15 g of Schaefer Precarb 400 CaCO.sub.3 powder and filled at an assembly rotor speed of 8000 rpm (100 m/s). The added materials were processed for 3 min. Altogether 2 repeats were carried out with the same amounts of materials and the same machine settings. Altogether about 196 g of structured composite particles were obtained.

(25) The SEM analysis of the structured composite particles obtained is depicted in FIG. 4a, 4b.

(26) The CaCO.sub.3 content determined using thermogravimetric analysis was 14.1% of PCC.

(27) The particle size distribution of the structured composite particles obtained was determined using laser diffraction (Sympatec, Helos) as d50=51 m.