POLYKETONE POWDER FOR LASER SINTERING

1 . A composition comprising a semicrystalline polyketone powder that has a melt peak having a melt peak enthalpy of at least 50 joules/gram as determined by differential scanning calorimetry (DSC) using a heating rate of 10° C./min.

2 . The composition of claim 1 , wherein the composition has a D 90 particle size of at most 300 micrometers and average particle size of 1 micrometer to 150 micrometers equivalent spherical diameter.

3 . The composition of claim 1 , wherein at least 80% by number of the particles of the semicrystalline polyketone powder has a circularity of at least about 0.8.

4 . The composition of claim 1 , wherein the polyketone is comprised of repeating units represented by:

where A is the residue of an alkene monomer converted to a saturated hydrocarbon group, m is from about 1 to 6 and n is at least about 2 to 10,000.

5 . The composition of claim 4 , wherein the semicrystalline polyketone powder is a copolymer of ethylene, carbon monoxide and at least one other alkene monomer.

6 . The composition of claim 5 , wherein the other alkene monomer is propylene.

7 . The composition of claim 1 , wherein the melt peak and recrystallization peak fail to overlap.

8 . The composition of claim 7 , wherein the melt peak has an onset melt peak temperature and a recrystallization peak onset temperature that are at least separated by 10° C.

9 . The composition of 1, wherein semicrystalline polyketone powder has: (i) a D 90 particle size of less than about 150 μm, (ii) a D 10 of at least 10 μm and (iii) an average particle size of about 20 μm to about 150 μm.

10 . The composition of claim 1 , wherein the melt peak has a melt enthalpy of at least 75 joules/gram.

11 . A method for forming a semicrystalline polyketone powder useful for making an additive manufactured article comprising;

(i) dissolving an initial polyketone having an onset melt temperature in a solvent above 50° C. to below the onset melt temperature of the initial polyketone to form a solution comprised of a dissolved polyketone,

(ii) precipitating the dissolved polyketone by cooling the solution, adding a non-solvent to the solution or combination thereof to form the semicrystalline polyketone powder, and

(iii) separating the semicrystalline polyketone powder from the solvent.

12 . The method of claim 11 , further comprising comminuting the polyketone powder to form a comminuted polyketone powder.

13 . The method of claim 11 further comprising heating the semicrystalline polyketone powder of step (iii) to a temperature within 20% of the onset melt temperature of the semicrystalline polyketone to form a heat-treated polyketone.

14 . The method of claim 13 , wherein the semicrystalline polyketone powder has a melt peak enthalpy of at least 75 joules/gram.

15 . The method of claim 12 , wherein the comminuted polyketone powder has (i) a D 90 particle size of less than about 150 μm, (ii) a D 10 of at least 10 μm, (iii) an average particle size of about 20 μm to about 150 μm, and (iv) at least 80% by number of the comminuted polyketone powder has a circularity of at least about 0.8.

16 . The method of claim 13 , wherein the conditions to increase the crystallinity is comprised of heat treating any one of the said polyketone powders to a temperature from 50° C. to below the melt peak temperature as determined by DSC for a time to increase the crystallinity forming an increased crystallinity polyketone.

17 . The method of claim 11 , wherein the dissolving is at a temperature from 100° C. to 150° C.

18 . The method of claim 11 , wherein the precipitating is performed by adding a nonsolvent comprised of water.

19 . The method of claim 17 , wherein the precipitating is performed at a temperature of 80° C. to less than 100° C.

20 . The method of claim 11 , wherein the solvent is a polar aprotic solvent having a dielectric constant of 15 to 50.