POLYKETONE POWDER FOR LASER SINTERING
In one instance a semicrystalline polyketone powder useful for additive manufacturing is comprised of a bimodal melt peak determined by an initial differential scanning calorimetry (DSC) scan at 20° C./min and a D 90 particle size of at most 300 micrometers and average particle size of 1 micrometer to 150 micrometers equivalent spherical diameter. In another instance, A composition is comprised of a semicrystalline polyketone powder having a melt peak and a recrystallization peak, wherein the melt peak and recrystallization peak fail to overlap.
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9 . A method of forming an additive manufactured article comprising selectively fusing by directed melting of a composition comprised of a semicrystalline polyketone powder having a melt peak and a recrystallization peak as determined by differential scanning calorimetry (DSC) scanned at a 20° C./min heating and cooling rate, wherein the melt peak and recrystallization peak fail to overlap.
10 . The method of claim 9 , wherein the melt peak has a melt peak onset temperature and a recrystallization onset temperature that are at least separated by 10° C.
11 . The method of claim 10 , wherein the semicrystalline polyketone has a crystallinity of at least about 15% by volume.
12 . The method of claim 11 , wherein the 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 50 μm.
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20 . The method of claim 9 , wherein the melt peak is monomodal.
21 . The method of claim 9 , 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.
22 . The method of claim 9 , wherein the semicrystalline polyketone powder is a copolymer of ethylene, carbon monoxide and at least one other alkene containing monomer.
23 . The method of claim 22 , wherein the other alkene containing monomer is an olefin.
24 . The method of claim 23 , wherein the olefin is propylene.
25 . The method of claim 22 , wherein ethylene is present at a ratio of ethylene to the other alkene in a ratio of about 2 to 100.
26 . The method of claim 25 , wherein the polyketone is terminated with an alkyl group, hydroxyl, ester, carboxylic acid, ether or combination thereof.
27 . The method of claim 26 , wherein the powder has a flowability of at least about 0.5 g/s as determined by ASTM D 1895 using a 15 mm nozzle.
28 . The method of claim 27 , wherein the composition is further comprised one or more of a UV stabilizer, filler, lubricant, plasticizer, pigment, flow aid, flame retardant, or solvent.
29 . The method of claim 9 wherein the composition is essentially free of a solvent.
30 . The method of claim 9 , wherein the semicrystalline polyketone powder is subjected to conditions that increase its crystallinity prior to selectively fusing.
31 . The method of claim 30 , wherein the conditions to increase the crystallinity comprises heat treating the semicrystalline powder to a temperature within 50° C. below the peak melt temperature as determined by DSC for a time to increase the crystallinity.