权利要求：
1. A method of three-dimensional printing an object having a varying degree of
transmissivity to light along an axis of said object, the method comprising the
steps of:
5 (a) providing a liquefied polymer resin having a plurality of particles therein,
said particles being distributed in said liquefied polymer resin based on the
density of said particles; and
(b) polymerizing said liquefied polymer resin under conditions to form said
object layer-by-layer.
2. The method according to claim 1, further comprising, before said providing step
(a), the steps of:
(a1) providing a homogenous suspension of said particles within said liquefied
polymer resin; and
15 (a2) allowing the particles to distribute within said liquefied polymer resin
based on their density values after a period of time.
3. The method according to claim 1 or 2, wherein said liquefied polymer resin
further comprises a photoinitiator.
4. The method according to any one of the preceding claims, wherein said
liquefied polymer resin further comprises a photoadditive selected from a
photoabsorber or a photostabilizer.
25 5. The method according to any one of the preceding claims, wherein said
polymerizing step (b) comprises the step of:
(b1) exposing each layer to light.
6. The method according to any one of the preceding claims, further comprising
30 the step of:
(c) post-treating the formed object.
7. A formulation for three-dimensional printing comprising:
(i) a liquefied polymer resin;
35 (ii) a plurality of particles having various density values;
(iii) a photoinitiator; and
(iv) optionally a photoadditive.
8. The formulation according to claim 7, wherein said formulation comprises:
40 (i) 60 to 95 wt% liquefied polymer resin;
(ii) 5 to 40 wt% particles;
(iii) 0.1 to 5 wt% photoinitiator; and
(iv) 0 to 0.2 wt% photoadditive, based on the weight of the formulation.
9. The formulation according to claim 7 or 8, wherein said particles have densities
in the range of 3 g/cm3 to 12 g/cm3.
10. The formulation according to any one of claims 7 to 9, wherein said particles
5 have a particle size in the range of 50 nm to 50 microns
11. The formulation according to any one of claims 7 to 10, wherein said particles
have a shape that is selected from the group consisting of spheres, rods, fibers,
plates and star-shaped.
12. The formulation according to any one of claims 7 to 11, wherein said liquefied
polymer resin comprises an acrylate.
13. The formulation according to claim 12, wherein said acrylate is a monomer or
15 oligomer selected from the group consisting of bisphenol A dimethacrylate
(Bis-DMA), bisphenol A diglycidyl ether methacrylate (Bis-GMA), ethoxylated
bisphenol-A dimethacrylate (Bis-EMA), Tricyclo[5.2.1.02,6]decanedimethanol
diacrylate, Bisphenol A glycerolate diacrylate, Bisphenol A ethoxylate
diacrylate, Bisphenol A ethoxylate dimethacrylate (oligo), Bisphenol F
20 ethoxylate diacrylate (oligo), Poly(ethylene glycol) diacrylate, Di(ethylene
glycol) diacrylate, Tetra(ethylene glycol) diacrylate, 1,4-Butanediol diacrylate,
Hydroxy ethylmethacrylate, 3,4-epoxy-cyclohexyl-methyl methacrylate
(METHB), triethylene glycol dimethacrylate (TEGDMA), Tertiobutyl
cyclohexanol methacrylate, 1,6-bis[2-(methacryloyloxy)
25 ethoxycarbonylamino]-2,4,4-trimethylhexane (UDMA), 3,3,5-trimethyl
cyclohexanol methacrylate, Dipentaerythritol penta-/hexa-acrylate and mixtures
thereof.
14. The formulation according to any one of claims 7 to 13, wherein said particles
30 are selected from the group consisting of metal oxides, metal nitrides, metal
carbides, metalloid oxides, metalloid nitrides and metalloid carbides.
15. The formulation according to claim 14, wherein the metal or metalloid of said
metal oxides, metal nitrides, metal carbides, metalloid oxides, metalloid nitrides
35 or metalloid carbides is selected from Group 2, Group 3, Group 4, Group 5,
Group 6, Group 8, Group 11, Group 12, Group 13, Group 14 or the lanthanide
series of the Periodic Table of Elements.
16. The formulation according to claim 15, wherein said particles are selected from
40 the group consisting of zinc oxide, Silicon carbide, Silicon nitride, Gallium
nitride, Aluminium oxide, Titanium dioxide, Zirconium dioxide, Tin dioxide,
Iron (III) oxide, Magnesium oxide, Indium (III) oxide, Tungsten trioxide,
Tungsten (IV) oxide, Silver oxide, Vanadium (V) oxide, Vanadium (IV) oxide,
Molybdenum trioxide, Yttrium (III) oxide, Cerium (IV) oxide and Copper (II)
45 oxide.
17. The formulation according to any one of claims 7 to 16, wherein said
photoinitiator is a type I or type II photoinitiator.
18. The formulation according to claim 17, wherein said photoinitiator is selected
5 from the group consisting of bis(2,4, 6-trimethyl benzoyl)phenylphosphine
oxide (IRGACURE 819), Phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide
(BAPO), 2,4,6-trimethylbenzoyl diphenyl phosphine (TPO), 2-hydroxy-2-
methyl-1 -phenyl-1-propane (DAROCUR 1173) and benzophenone (BP).
10 19. The formulation according to any one of claims 7 to 18, wherein said
photoadditive is a photoabsorber selected from the group consisting of Sudan I-
IV, 2,5-Bis(5-tert-butyl-benzoxazol-2-yl)thiophene, 4-methoxyphenol and
butylated hyrdorxytoluene.
15 20. A three-dimensional printed object having a varying degree of transmissivity to
light along an axis of said object.