Powder comprising polymer-coated glass particles
Composite particles comprising core particles completely or partially coated with a precipitated polymer, where the d 50 median diameter of the core particles is from 3 to 100 μm and wherein the glass core particle material is at least one selected from the group consisting of a solid glass bead, a hollow glass bead, a porous glass bead, and a foamed glass particle. A method to prepare the particles includes dissolution of a polymer in a solvent and precipitation of the polymer in the presence of a suspension of the core glass particles. Further provided is a layer by layer moulding process employing the composite particles and mouldings obtained therefrom.
1. A powder, comprising composite particles:
wherein the composite particles, comprise:
a core glass particle having a d 50 median diameter of 3 to 100 μm; and
at least a partial coating of a polymer on the core;
wherein a ratio of the d 50 median diameter of the composite particles to the d 50 median diameter of the core glass particles is from 1.01 to 5.0, and
wherein a number average weight ratio of the polymer coating to the core glass particle, is from 1 to 30.
2. The powder according to claim 1 , wherein
the core glass particle is at least one selected from the group consisting of a solid glass bead, a hollow glass bead, a porous glass bead, and a foamed glass particle, and
the core glass particle is optionally sized in the composite particle.
3. The powder according to claim 2 , wherein the d 50 median diameter of the core glass particles is from 3 to 80 μm.
4. The powder according to claim 1 , wherein the polymer of the coating comprises at least one polymer selected from the group consisting of a polyolefin, a polyethylene, a polypropylene, a polyvinyl chloride, a polyacetal, a polystyrene, a polyimide, a polysulphone, a poly(N-methylmethacrylimide) (PMMI), a polymethyl methacrylate (PMMA), a polyvinylidene fluoride (PVDF), an ionomer, a polyether ketone, a polyaryl ether ketone, a polyamide, and a copolyamide.
5. The powder according to claim 1 , wherein a d 50 median diameter of the composite particles is from 20 to 150 μm.
6. The powder according to claim 1 , wherein a ratio of the d 50 median diameter of the composite particles to the d 50 median diameter of the core glass particles is from 1.05 to 5.0.
7. The powder according to claim 1 , wherein an aspect ratio of the core glass particle is 20 or less.
8. The powder according to claim 1 , wherein a density of the core glass particles is from 0.1 to 6.6 g/cm 3 .
9. The powder according to claim 1 , wherein the coating polymer is a polyamicle having at least 8 carbons per carbonamide group.
10. The powder according to claim 9 , wherein the polyamide is at least one selected from the group consisting of nylon-6,12, nylon-11 and nylon-12.
11. The powder according to claim 1 , which further comprises at least one selected from the group consisting of a powder-flow aid, an organic pigment, an inorganic pigment, and a sterically hindered phenol.
12. The powder according to claim 11 , wherein a content of the composite particles in the powder is at least 50% by weight.
13. The powder according to claim 1 , wherein the number average weight ratio of the polymer coating to the core glass particle, is from 1.4 to 10.
14. A process for producing the composite particles according to claim 1 , the process comprising:
at least partially dissolving a polymer for the coating in a medium comprising a solvent which at least partially dissolves the polymer;
adding the core glass particles to the medium, before, during or after at least partially dissolving the polymer;
suspending the core glass particles in the medium; and then
precipitating the polymer from the at least partial solution onto the core glass particles to obtain the composite particles;
wherein a ratio of the d 50 median diameter of the composite particles to the d 50 median diameter of the core glass particles is from 1.01 to 5.0.
15. The process according to claim 14 , wherein a density of the core particles is greater or not more than 20% smaller than the density of the solvent used for the precipitation of the polymer.
16. The process according to claim 14 , wherein the solvent for the polymer is ethanol and a density of the core particles is greater or not more than 20% smaller than the density of ethanol.
17. A process for producing a moulded article, the process comprising:
applying a layer of the composite powder according to claim 1 ;
selectively melting at least one region of the layer by introduction of electromagnetic energy;
allowing the melted region to solidify;
applying another layer of composite powder and repeating the melting and solidification to perform a layer-by-layer process in which a molding having a structure according to the selective treatment is obtained;
wherein the melting selectivity is achieved by applying susceptors, inhibitors, or absorbers to each applied layer or by applying a mask to the applied layer.
18. A moulded article obtained according to the process of claim 17 .