METHOD AND APPARATUS FOR MANUFACTURE OF 3D OBJECTS

1 . An apparatus for manufacture of a three-dimensional object, comprising: a tank for storing a pseudoplastic flame retardant material at atmospheric pressure;

a pump configured to apply agitation to the pseudoplastic flame retardant material to shear thin the pseudoplastic material and reduce the pseudoplastic material viscosity such as to cause the material to flow;

an extrusion unit comprising an extrusion nozzle configured to extrude in image-wise manner the pseudoplastic flame retardant material at a pressure exceeding atmospheric pressure; and

an X-Y-Z movement system configured to move at least the extrusion nozzle in a three coordinate system and at a speed sufficient to support the bond between first and second extruded strips or portions of pseudoplastic material to become strong enough to support the second extruded strip or portion of the pseudoplastic material in a suspended state only once the second extruded strip of pseudoplastic flame retardant material has dropped into a horizontal position alongside the first extruded strip or portion of pseudoplastic material.

2 . The apparatus according to claim 1 , further comprising a source of radiation configured to harden the pseudoplastic flame retardant material, the source of radiation configured to continuously operate to harden the pseudoplastic material; wherein optionally the source of radiation is an ultra violet radiation source emitting light of a wavelength between 380 and 420 nm; and/or wherein optionally the source of radiation is one of a group of ultra violet radiation sources consisting of an assembly of LEDs or a UV curing lamp.

3 . The apparatus according to claim 1 , wherein diameter of the extrusion nozzle is set to extrude a strip or a portion of the pseudoplastic material with a diameter in the range of 0.5 to 2.0 mm.

4 . A pseudoplastic material for printing of cantilever-like three-dimensional objects comprising:

30-70 weight-% of at least one curable oligomer,

30-70 weight-% of at least one reactive diluent,

0.2-7 weight-% of at least one curing agent:

1-10 weight-% of at least one rheology modifier, and

0-40 weight-% of at least one flame retardant.

5 . The pseudoplastic material according to claim 4 , wherein the curable oligomer is at least one curable oligomer of a group of oligomers having at least one ethylenically unsaturated group comprised of urethane, epoxy, ester and/or ether units; and/or

wherein the reactive diluent is one of a group of low molecular weight compounds having at least one functional group reactive with the oligomer in the presence of a curing agent, wherein the reactive diluent optionally is selected from acrylate esters consisting of monoacrylates, diacrylates, triacrylates, mono-, di-, or tri-methacrylates; and/or

wherein the curing agent is a photo initiator of an alpha cleavage type absorbing light between about 230 and 420 nm, wherein the curing agent optionally is 1-hydroxy-cyclohexyl-phenylketone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone-1, bis(2,4,6-trimethylbenzoyl)phenylphosphinoxid, or diphenyl(2,4,6-trimethylbenzoyl)-phosphinoxide; and/or

wherein the rheology modifier is fumed silica; and

wherein the performance additive filler is a flame retardant material

6 . The pseudoplastic material according to claim 4 , wherein a first viscosity of the material before extrusion is in a range of about 120,000.00 mPa·s to about 500,000.00 mPa·s at atmospheric pressure; and/or wherein a second viscosity of the material when a force is applied is in a range of about 250 to about 700 mPa·s.

7 . The pseudoplastic material according to claim 4 , wherein the performance additive is one of a group of additives consisting of pigments, fillers such as glass beads, glass fibers, surfactants, wetting and dispersing additives, impact modifiers, and/or flame retardants.

8 . A method of forming a three-dimensional object comprising:

a) providing a highly viscous pseudoplastic flame retardant material having a first viscosity and agitating the material to shear the pseudoplastic flame retardant material thereby decreasing viscosity to a second viscosity and to cause it to flow through a delivery system to an extrusion unit;

b) employing an extrusion unit to extrude a first portion of the pseudoplastic flame retardant material in image-wise manner, the first portion having a cross section with a diameter;

c) illuminating the first extruded portion to harden the pseudoplastic flame retardant material;

d) extruding a second portion of the pseudoplastic flame retardant material adjacent to the first portion and contacting the first portion at at least one contact point, wherein a cross section of the second portion is shifted in an axis perpendicular to gravitational force compared to the cross section of the first portion;

e) obtaining a common contact section between surfaces of the first and second extruded portions by forming an envelope into which a segment of the first portion protrudes by sliding, due to the gravitational force, of the second portion along the circumference of the surface of the first portion hardened in step c), wherein the surface of the second portion wets the surface of the first portion at the common contact section;

f) illuminating the extruded second portion to harden the pseudoplastic flame retardant material and to form a bond between the first and second portions of pseudoplastic material at the common contact section;

g) adjusting the relative position between extrusion unit and extruded second portion such that the second portion obtains the location of the extruded first portion of step b); and

repeating steps d) to g) until the three-dimensional object has been formed.

9 . The method of forming a three-dimensional object according to claim 8 , wherein the flame retardant material is at least one of a group of flame retardants consisting of brominated polymers, oligomeric phosphate ester (Resorcinol bis(diphenyl phosphate)) or aromatic phosphate ester, inorganic flame retarders, nitrogen flame retarders and a mix of the above.