AMORPHOUS THERMOPLASTIC ADDITIVE MANUFACTURED ARTICLES AND METHOD TO MAKE THEM
A semi-crystalline blended polymer useful for additive manufacturing is comprised of an amorphous thermoplastic polymer and a thermoplastic semi-crystalline polymer, each of the polymers being essentially miscible in the other and being blended at a weight ratio of amorphous polymer/semi-crystalline polymer of greater that 1 to about 20. The semi-crystalline blended polymer displays a DSC melt peak enthalpy of at least about 3 joules/g. The semi-crystalline polymer may be made by blending the aforementioned polymers at the weight ratio and subject to heating between the melt temperature of the semi-crystalline polymer and the glass transition temperature of the amorphous polymer. The semi-crystalline blended polymer may revert to essentially an amorphous polymer when additive manufactured by fusing layers of said polymer powders together.
1 . A semi-crystalline blended polymer comprising, an amorphous thermoplastic polymer and a thermoplastic semi-crystalline polymer, each of the polymers being essentially miscible in the other and being blended at a weight ratio of amorphous polymer/semi-crystalline polymer of greater that 1 to about 20 and said blended semi-crystalline polymer displaying a DSC melt peak enthalpy of at least about 3 joules/g.
2 . The semi-crystalline blended polymer of claim 1 , wherein the weight ratio is 10 to 3.
3 . The semi-crystalline blended polymer of claim 1 , wherein the amorphous thermoplastic polymer has a glass transition temperature of about 60° C. to about 120° C. and the semi-crystalline thermoplastic polymer has a melting temperature as determined by DSC of at least about 140° C.
4 . The semi-crystalline blended polymer of claim 1 , wherein the melt peak enthalpy of a neat thermoplastic semi-crystalline polymer is less than the melt peak enthalpy of the semi-crystalline blended polymer.
5 . The semi-crystalline blended polymer of claim 1 , wherein the amorphous polymer is a polymethyl methacrylate and the semi-crystalline polymer is a polyester.
6 . The semi-crystalline blended polymer of claim 1 , wherein the amorphous polymer is an amorphous polyamide and the semi-crystalline polymer is a semi-crystalline polyamide.
7 . The semi-crystalline blended polymer of claim 1 , wherein said semi-crystalline blended polymer has a melt temperature of least about 150° C. to about 225° C.
8 . The semi-crystalline blended polymer of claim 1 , wherein said semi-crystalline blended polymer is a powder having a D10 of at least 1 micrometer, a D50 of about 20 micrometers to 100 micrometer, and a D90 of at most about 200 micrometers equivalent spherical diameter.
9 . The semi-crystalline blended polymer of claim 1 , wherein said semi-crystalline blended polymer is essentially free of a solvent.
10 . A method of forming a semi-crystalline blended polymer comprising:
a. melt blending an amorphous thermoplastic polymer and a thermoplastic semi-crystalline polymer, each of the polymers being essentially miscible in the other, at a weight ratio of the amorphous polymer/semi-crystalline polymer that is greater than 1 to about 20 to form a blended polymer, and
b. heat-treating the blended polymer at a crystallizing temperature above the glass transition temperature of the amorphous thermoplastic polymer but below the melt temperature of the semicrystalline polymer for a heat-treating time to crystallize the blended polymer sufficiently to realize the semi-crystalline blended polymer.
c.
11 . The method of claim 10 , wherein the heat-treating is for a heat-treating time of at least about 2 hours.
12 . The method of claim 10 , wherein the blended polymer is essentially amorphous.
13 . The method of claim 10 , wherein the semi-crystalline blended polymer has a DSC melting peak enthalpy of at least about 5 Joules/g and melt temperature of at least about 140° C.
14 . The method of claim 10 , wherein at least portion of the heat treating is performed at temperature that is below, but within 20° C. of the melt temperature of the semi-crystalline polymer.
15 . The method of claim 10 , wherein the heat-treating temperature is from about 100° C. to about 180° C.
16 . The method of claim 15 , wherein the heat-treating temperature is at most about 175° C.
17 . A method of forming an additive manufactured article comprising,
a. spreading a layer of a semi-crystalline blended polymer powder comprised of an amorphous thermoplastic polymer and a thermoplastic semi-crystalline polymer, each of the polymers being essentially miscible in the other and being blended at a weight ratio of amorphous polymer/semi-crystalline polymer of greater that 1 to about 20 and said blended semi-crystalline polymer powder displaying a DSC melt peak enthalpy of at least about 3 joules/g,
b. heating and fusing the particles of the layer in a controlled manner by directed electromagnetic radiation,
c. spreading subsequent layers of the semicrystalline blended powder and fusing each layer to its prior layer in a controlled manner by directed electromagnetic radiation to form the additive manufactured article comprised of an additive manufactured article's polymer.
18 . The method of claim 17 , wherein the additive manufactured article's polymer is essentially amorphous.
19 . The method of claim 17 , further comprising heating between the transition temperature of the amorphous polymer and melt temperature of the semi-crystalline polymer causing the additive manufactured article's polymer to recrystallize.