Dimensionally stable acrylic alloy for 3-d printing
An acrylic alloy composition that can be 3-D printed by a material extrusion additive manufacturing process, an acrylic filament that has a very uniform diameter useful in the extrusion additive manufacturing process, acrylic articles made from the acrylic alloy composition by a material extrusion additive process, and a material extrusion additive manufacturing process for producing the acrylic articles. The acrylic alloy composition is an alloy of an acrylic polymer, and a low melt viscosity polymer, such as polylactic acid. The alloy may optionally be impact modified, preferably with hard core core-shell impact modifiers.
1. An acrylic alloy composition for use in material extrusion additive manufacturing, said acrylic composition comprising:
a polymer matrix blend comprising:
1) One or more acrylic polymers having a weight average molecular weight of from 50,000 to 300,000 g/mol,
2) 5 to 60 weight percent of one or more low viscosity polymers that are compatible, semi-miscible, or miscible with the one or more acrylic polymers, said one or more low viscosity polymers having a melt flow rate of greater than 10 g/10 minutes, as measured by ASTM D1238 at 230° C./10.4 kg of force, and
3) no hard-core core shell impact modifiers,
wherein said acrylic composition has a viscosity at a shear of 1 sec −1 of less than 100,000 Pa-sec, at a temperature of 230° C., and a viscosity of 20 to 2,000 Pa-s, at a shear rate of 100 sec −1 at a temperature of 230° C., as measured by a rotational viscometer according to ASTM C965.
2. The acrylic composition of claim 1 , wherein said one or more acrylic polymers contains less than 5% by weight of polymer having a weight average molecular weight of greater than 500,000 g/mol.
3. The acrylic composition of claim 1 , wherein said composition comprises two or more different acrylic polymers.
4. The acrylic composition of claim 1 , wherein said one or more acrylic polymers comprise at least 60 weight percent of methyl methacrylate monomer units.
5. The acrylic composition of claim 1 , wherein said one or more low viscosity polymer(s) is a low molecular weight acrylic polymer, having a weight average molecular weight less than 50,000 g/mol.
6. The acrylic composition of claim 1 , wherein said one or more low viscosity polymer(s) is not an acrylic polymer, and is (are) selected from the group consisting of polyesters, cellulosic esters, polyethylene oxide, polypropylene glycol, polyethylene glycol, polypropylene glycol, styrene-acrylonitrile copolymers, polyvinyl chloride, polyvinyl acetate, polyvinyl alcohol, ethylene-vinyl acetate copolymers, olefin-acrylate copolymers, olefin-acrylate-maleic anhydride copolymers, polyvinylidene fluoride and maleic anhydride-styrene-vinyl acetate copolymers.
7. The acrylic composition of claim 6 , wherein said polyester is selected from the group consisting of poly (butylene terephthalate), poly (ethylene terephthalate), polyethylene terephthalate glycol, and polylactic acid.
8. The acrylic composition of claim 7 , wherein said polyester is polylactic acid.
9. The acrylic composition of claim 6 , wherein said cellulosic ester is selected from the group consisting of cellulose acetate, cellulose triacetate, cellulose propionate, cellulose acetate propionate, cellulose acetate butyrate, and cellulose acetate phthalate.
10. The acrylic composition of claim 1 , wherein said composition is clear and, when the clear composition is compression molded to a plaque having a thickness of 2 mm, the plaque has a total white light transmittance of greater than 80%, when measured according to ASTM D1003, and has a haze of less than 10%.
11. The acrylic composition of claim 1 , wherein said composition is in the form of a powder, pellets or filament.
12. The acrylic composition of claim 1 , further comprising one or more additives selected from the group consisting of fillers, carbon fiber, milled carbon fiber, carbon powder, carbon nanotubes, glass beads, glass fibers, nano-silica, clays, nanoclays, Aramid fiber, polyaryl ether ketone fibers, BaSO 4 , talc, CaCO 3 , graphene, milled carbon fibers, nano-fibers, and hollow spheres, dyes, colorants, pigment, metallic particles, metallic flakes, opalescent dyes, fluorescent dyes, and mixtures thereof.
13. The acrylic composition of claim 1 , further comprising one or more additives, selected from the group consisting of carbon fiber, carbon powder, milled carbon fiber, carbon nanotubes, glass beads, glass fibers and mixtures thereof.
14. The acrylic composition of claim 1 , further comprising one or more additives, selected from the group consisting of carbon fiber, milled carbon fiber, glass fibers and mixtures thereof.
15. The acrylic composition of claim 1 , further comprising one or more additives, selected from the group consisting of colorants, dyes, and inorganic particles, including fluorescent dyes, metal filings, and flakes and mixtures thereof.
16. The acrylic composition of claim 12 , wherein the additives are selected from the group consisting of carbon fiber, carbon powder, milled carbon fiber, carbon nanotubes, glass beads, glass fibers, nano-silica, Aramid fiber, polyarylether ketone fibers, BaSO 4 , talc, CaCO 3 , graphene, nano-fibers and hollow glass or ceramic spheres.
17. The acrylic composition of claim 12 , wherein the additives are present 0.01 to 50 volume percent of the total volume of the composition.
18. A process of preparing the composition of claim 1 , the process comprising dry-blending the polymer matrix blend and optionally additives prior to melting, or directly melt blending the polymer matrix blend and optionally additives together in an extruder, or intimately mixing the polymer matrix blend and optionally additives in a solvent.