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Número de publicaciónUS20060230984 A1
Tipo de publicaciónSolicitud
Número de solicitudUS 11/453,695
Fecha de publicación19 Oct 2006
Fecha de presentación15 Jun 2006
Fecha de prioridad25 Sep 2002
También publicado comoCA2500012A1, EP1542858A1, EP1542858B1, US7087109, US20040056378, WO2004028787A1
Número de publicación11453695, 453695, US 2006/0230984 A1, US 2006/230984 A1, US 20060230984 A1, US 20060230984A1, US 2006230984 A1, US 2006230984A1, US-A1-20060230984, US-A1-2006230984, US2006/0230984A1, US2006/230984A1, US20060230984 A1, US20060230984A1, US2006230984 A1, US2006230984A1
InventoresJames Bredt, Sarah Clark, Grieta Gilchrist
Cesionario originalZ Corporation
Exportar citaBiBTeX, EndNote, RefMan
Enlaces externos: USPTO, Cesión de USPTO, Espacenet
Three dimensional printing material system and method
US 20060230984 A1
Resumen
The present invention is directed to a three-dimensional printing system and method, and an article made therefrom. The method of the present invention includes building cross-sectional portions of a three dimensional article, and assembling the individual cross-sectional areas in a layer-wise fashion to form a final article. The individual cross-sectional areas are built using an ink-jet printhead to deliver an aqueous fluid to a particle material that includes a first particulate material, a second particulate material, and a third particulate material, wherein the first and second particulate materials react in the presence of the fluid in a period of time, and the third particulate material reacts in the presence of the fluid to form a solid in a longer period of time.
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Reclamaciones(48)
1. A solid article comprising:
a product of a mixture of a plurality of particles of:
a first particulate material comprising a phosphate;
a second particulate material comprising an oxide; and
a third particulate material comprising an adhesive,
wherein the first particulate material and the second particulate material can react to form a solid in a period of time, and the third particulate material can solidify in a longer period of time when the mixture is contacted by a fluid during three-dimensional printing, the article having been formed by three-dimensional printing and comprising a plurality of layers of the mixture.
2. The article of claim 1, wherein the first particulate material and the second particulate material react in the presence of a fluid.
3. The article of claim 2, wherein at least one of the first particulate material and the second particulate material is substantially soluble in the fluid.
4. (canceled)
5. The article of claim 1, wherein the phosphate is selected from the group consisting of monoammonium phosphate; sodium aluminum phosphate, acidic; monocalcium phosphate, anhydrous; monopotassium phosphate; monosodium phosphate; and aluminum acid phosphate.
6. The article of claim 1, wherein the phosphate is selected from the group consisting of: sodium tripolyphosphate; sodium hexametaphosphate; sodium polyphosphate, anhydrous; phosphoric acid, sodium salt; sodium trimetaphosphate; and ammonium polyphosphate.
7. The article of claim 1, wherein the phosphate is selected from the group consisting of diammonium phosphate; dipotassium phosphate; disodium phosphate; monocalcium phosphate dihydrate; monocalcium phosphate, monohydrate; dicalcium phosphate, dihydrate; dicalcium phosphate, anhydrous; tricalcium phosphate; disodium phosphate; and tripotassium phosphate.
8. The article of claim 1, wherein the phosphate is selected from the group consisting of sodium acid pyrophosphate; tetrasodium pyrophosphate; and tetrapotassium pyrophosphate.
9. (canceled)
10. The article of claim 1, wherein the second particulate material comprises at least one of an alkaline oxide, an alkaline hydroxide, and a combination thereof.
11. The article of claim 10, wherein the alkaline oxide is selected from the group consisting of: zinc oxide; magnesium oxide; calcium oxide; copper oxide; bismuth oxide; cadmium oxide; tin oxide; red lead oxide; and combinations thereof.
12. The article of claim 10, wherein the alkaline hydroxide is selected from the group consisting of: magnesium hydroxide; cobalt trihydroxide; beryllium dihydroxide and combinations thereof.
13. The article of claim 10, wherein the alkaline oxide comprises magnesium oxide.
14-15. (canceled)
16. The article of claim 1, wherein the adhesive is selected from the group consisting of: copolymer of octylacrylamide/acrylates/butylaminoethyl methacrylate; polyvinyl alcohol; polyethylene oxide; sodium polystyrene sulfonate; polyacrylic acid; polyvinyl pyrrolidone; maltodextrine; hydrolyzed gelatin; sugar; hydrolyzed starch; sodium salt of polymethacrylic acid; ammonium salt of polymethacrylic acid; polyvinyl sulfonic acid; sulfonated polyester; poly(2-ethyl-2-oxazoline); polymethacrylic acid; sodium salt of polyacrylic acid; ammonium salt of polyacrylic acid; and combinations thereof.
17. The article of claim 1, wherein the mixture of plurality of particles further comprises a filler.
18. The article of claim 17, wherein the filler is selected from the group consisting of: limestone, staurolite, silica sand, zircon sand, olivine sand, chromite sand, magnesite, alumina silicate, calcium silicate, fused silica, calcium phosphate, rutile, bentonite, montmorillonite, glass, chamotte, fireclay, and mixtures thereof.
19. The article of claim 2, wherein the fluid is aqueous.
20-27. (canceled)
28. A compound used in three dimensional printing comprising:
a dry particulate mixture of:
a first particulate material comprising a phosphate;
a second particulate material comprising an oxide; and
a third particulate material comprising an adhesive,
wherein the dry particulate mixture can be used in three-dimensional printing to form an article comprised of a plurality of layers, the first particulate material and the second particulate material can react to form a solid in a period of time, and the third particulate material can solidify in a longer period of time when the mixture is contacted by a fluid during three-dimensional printing.
29. The compound of claim 28, wherein the first particulate material and the second particulate material react in the presence of the fluid.
30. The compound of claim 29, wherein at least one of the first particulate material and the second particulate material is substantially soluble in the fluid.
31. (canceled)
32. The compound of claim 28, wherein the phosphate is selected from the group consisting of monoammonium phosphate; sodium aluminum phosphate, acidic; monocalcium phosphate, anhydrous; monopotassium phosphate; monosodium phosphate; and aluminum acid phosphate.
33. The compound of claim 28, wherein the phosphate is selected from the group consisting of: sodium tripolyphosphate; sodium hexametaphosphate; sodium polyphosphate, anhydrous; phosphoric acid, sodium salt; sodium trimetaphosphate; and ammonium polyphosphate.
34. The compound of claim 28, wherein the phosphate is selected from the group consisting of diammonium phosphate; dipotassium phosphate; disodium phosphate; monocalcium phosphate dihydrate; monocalcium phosphate, monohydrate; dicalcium phosphate, dihydrate; dicalcium phosphate, anhydrous; tricalcium phosphate; disodium phosphate; and tripotassium phosphate.
35. The compound of claim 28, wherein the phosphate is selected from the group consisting of sodium acid pyrophosphate; tetrasodium pyrophosphate; and tetrapotassium pyrophosphate.
36. (canceled)
37. The compound of claim 28, wherein the second particulate material comprises at least one of an alkaline oxide, an alkaline hydroxide, and a combination thereof.
38. The compound of claim 37, wherein the alkaline oxide is selected from the group consisting of: zinc oxide; magnesium oxide; calcium oxide; copper oxide; bismuth oxide; cadmium oxide; tin oxide; red lead oxide; and combinations thereof.
39. The compound of claim 37, wherein the alkaline hydroxide is selected from the group consisting of: magnesium hydroxide; cobalt trihydroxide; beryllium dihydroxide and combinations thereof.
40. The compound of claim 37, wherein the alkaline oxide comprises magnesium oxide.
41-42. (canceled)
43. The compound of claim 28, wherein the adhesive is selected from the group consisting of: copolymer of octylacrylamide/acrylates/butylaminoethyl methacrylate; polyvinyl alcohol; polyethylene oxide; sodium polystyrene sulfonate; polyacrylic acid; polyvinyl pyrrolidone; maltodextrine; hydrolyzed gelatin; sugar; hydrolyzed starch; sodium salt of polymethacrylic acid; ammonium salt of polymethacrylic acid; polyvinyl sulfonic acid; sulfonated polyester; poly(2-ethyl-2-oxazoline); polymethacrylic acid; sodium salt of polyacrylic acid; ammonium salt of polyacrylic acid; and combinations thereof.
44. The compound of claim 28, wherein the mixture of plurality of particles further comprises a filler.
45. The compound of claim 44, wherein the filler is selected from the group consisting of: limestone, staurolite, silica sand, zircon sand, olivine sand, chromite sand, magnesite, alumina silicate, calcium silicate, fused silica, calcium phosphate, rutile, bentonite, montmorillonite, glass, chamotte, fireclay, and mixtures thereof.
46. The compound of claim 29, wherein the fluid is aqueous.
47-83. (canceled)
84. A dry particulate mixture of solids used for three dimensional printing that, when contacted by a fluid during three-dimensional printing to form an article composed of a plurality of layers, undergoes a first solidification reaction beginning with the fluid contact and occurring at a first rate, and also undergoes a second solidification reaction beginning with the fluid contact and occurring at a second rate slower than the first rate, wherein the dry particulate mixture comprises:
a first particulate material comprising a phosphate;
a second particulate material comprising an oxide; and
a third particulate material comprising an adhesive.
85. The compound of claim 84, wherein the phosphate is selected from the group consisting of monoammonium phosphate; sodium aluminum phosphate, acidic; monocalcium phosphate, anhydrous; monopotassium phosphate; monosodium phosphate; and aluminum acid phosphate.
86. The compound of claim 84, wherein the phosphate is selected from the group consisting of: sodium tripolyphosphate; sodium hexametaphosphate; sodium polyphosphate, anhydrous; phosphoric acid, sodium salt; sodium trimetaphosphate; and ammonium polyphosphate.
87. The compound of claim 84, wherein the phosphate is selected from the group consisting of diammonium phosphate; dipotassium phosphate; disodium phosphate; monocalcium phosphate dihydrate; monocalcium phosphate, monohydrate; dicalcium phosphate, dihydrate; dicalcium phosphate, anhydrous; tricalcium phosphate; disodium phosphate; and tripotassium phosphate.
88. The compound of claim 84, wherein the phosphate is selected from the group consisting of sodium acid pyrophosphate; tetrasodium pyrophosphate; and tetrapotassium pyrophosphate.
89. The compound of claim 84, wherein the second particulate material comprises at least one of an alkaline oxide, an alkaline hydroxide, and a combination thereof.
90. The compound of claim 89, wherein the alkaline oxide is selected from the group consisting of: zinc oxide; magnesium oxide; calcium oxide; copper oxide; bismuth oxide; cadmium oxide; tin oxide; red lead oxide; and combinations thereof.
91. The compound of claim 89, wherein the alkaline hydroxide is selected from the group consisting of: magnesium hydroxide; cobalt trihydroxide; beryllium dihydroxide and combinations thereof.
92. The compound of claim 89, wherein the alkaline oxide comprises magnesium oxide.
93. The compound of claim 84, wherein the adhesive is selected from the group consisting of: copolymer of octylacrylamide/acrylates/butylaminoethyl methacrylate; polyvinyl alcohol; polyethylene oxide; sodium polystyrene sulfonate; polyacrylic acid; polyvinyl pyrrolidone; maltodextrine; hydrolyzed gelatin; sugar; hydrolyzed starch; sodium salt of polymethacrylic acid; ammonium salt of polymethacrylic acid; polyvinyl sulfonic acid; sulfonated polyester; poly(2-ethyl-2-oxazoline); polymethacrylic acid; sodium salt of polyacrylic acid; ammonium salt of polyacrylic acid; and combinations thereof.
Descripción
    BACKGROUND
  • [0001]
    This application relates generally to rapid prototyping techniques and, more particularly to a Three. Dimensional Printing material and method using particulate mixtures.
  • [0002]
    The field of rapid prototyping involves the production of prototype articles and small quantities of functional parts, as well as structural ceramics and ceramic shell molds for metal casting, directly from computer-generated design data.
  • [0003]
    Two well-known methods for rapid prototyping include a selective laser sintering process and a liquid binder Three Dimensional Printing process. The techniques are similar to the extent that they both use layering techniques to build three-dimensional articles. Both methods form successive thin cross sections of the desired article. The individual cross sections are formed by bonding together grains of a granular material on a flat surface of a bed of the granular material. Each layer is bonded to a previously formed layer to form the desired three-dimensional article at the same time as the grains of each layer are bonded together. The laser-sintering and liquid binder techniques are advantageous because they create parts directly from computer-generated design data and can produce parts having complex geometries. Moreover, Three Dimensional Printing can be quicker and less expensive than conventional machining of prototype parts or production of cast or molded parts by conventional “hard” or “soft” tooling techniques which can take from a few weeks to several months, depending on the complexity of the item.
  • [0004]
    Three Dimensional Printing has been used to make ceramic molds for investment casting, thereby generating fully-functional metal parts. Additional uses have been contemplated for Three Dimensional Printing.
  • [0005]
    For example, three Dimensional Printing may be useful in design-related fields where it is used for visualization, demonstration and mechanical prototyping. It may also be useful for making patterns for molding processes. Three Dimensional Printing techniques may be further useful, for example, in the fields of medicine and dentistry, where expected outcomes may be modeled prior to performing procedures. Other businesses that could benefit from rapid prototyping technology include architectural firms, as well as others in which visualization of a design is useful.
  • [0006]
    A selective laser sintering process is described in U.S. Pat. No. 4,863,538 to Deckard, which is incorporated herein by reference for all purposes. The selective laser sintering process was commercialized by DTM and acquired by 3D Systems. The selective laser sintering process involves spreading a thin layer of powder onto a flat surface. The powder is spread using a tool developed for use with the selective laser sintering process, known in the art as a counter-rolling mechanism (hereinafter “counter-roller”). Using the counter-roller allows thin layers of material to be spread evenly, without disturbing previous layers. After the layer of powder is spread onto the surface, a laser directs laser energy onto the powder in a predetermined two-dimensional pattern. The laser sinters or fuses the powder together in the areas struck by its energy. The powder can be plastic, metal, polymer, ceramic or a composite. Successive layers of powder are spread over previous layers using the counter-roller, followed by sintering or fusing with the laser. The process is essentially thermal, requiring delivery by the laser of a sufficient amount of energy to sinter the powder together, and to previous layers, to form the final article.
  • [0007]
    U.S. Pat. No. 5,639,402 to Barlow, incorporated herein by reference for all purposes, discloses a method for selectively fusing calcium phosphate particles that are coated, or alternatively mixed with, a polymeric binder material.
  • [0008]
    U.S. Pat. No. 5,204,055, to Sachs et al. incorporated herein by reference for all purposes, describes an early Three Dimensional Printing technique which involves the use of an ink-jet printing head to deliver a liquid or colloidal binder material to layers of powdered material. The Three Dimensional inkjet printing technique (hereafter “liquid binder method”) involves applying a layer of a powdered material to a surface using a counter-roller. After the powdered material is applied to the surface, the ink-jet printhead delivers a liquid binder to the layer of powder. The binder infiltrates into gaps in the powder material, hardening to bond the powder material into a solidified layer. The hardened binder also bonds each layer to the previous layer. After the first cross-sectional portion is formed, the previous steps are repeated, building successive cross-sectional portions until the final article is formed. Optionally, the binder can be suspended in a carrier which evaporates, leaving the hardened binder behind. The powdered material can be ceramic, metal, plastic or a composite material, and can also include fiber. The liquid binder material can be organic or inorganic. Typical organic binder materials used are polymeric resins, or ceramic precursors such as polycarbosilazane. Inorganic binders are used where the binder is incorporated into the fmal articles; silica is typically used in such an application.
  • [0009]
    U.S. Pat. No. 5,490,962 to Cima, incorporated herein by reference for all purposes, discloses solid free-form techniques for making medical devices for controlled release of bioactive agents.
  • [0010]
    U.S. Pat. No. 6,397,922 to Sachs et al., incorporated herein by reference for all purposes, discloses a layered fabrication technique used to create a ceramic mold and is incorporated herein by reference for all purposes.
  • [0011]
    One advantage of using an inkjet printhead rather than a laser is that a plurality of spray nozzles used to deliver binder to the powder can be arranged side-by-side in a single printhead. In selective laser sintering machines, only one laser, which delivers energy to the powder, is conventionally used. The combination of several spray nozzles increases the speed of liquid binder printing compared to laser-sintering by allowing a wider area to be printed at one time. In addition, the liquid binder printing equipment is much less expensive than the laser equipment due to the high cost of the laser and the high cost of the related beam deflection optics and controls.
  • [0012]
    However, three-dimensional printing materials may be susceptible to deformation during and after the printing process if sufficient bond strength within and between layers has not adequately developed.
  • [0013]
    In addition, the powders, especially metallic powders, used in both selective laser sintering and liquid binder techniques present safety issues that render them undesirable for use in an office environment. These safety issues may require special clothing and processing facilities to prevent, for example, skin contact or inhalation of toxic materials. In addition, more expense may be incurred through complying with regulations for the disposal of toxic materials.
  • SUMMARY
  • [0014]
    One aspect of the invention is directed to an article comprising a product of a mixture of a plurality of particles of a first particulate material, a second particulate material and a third particulate material. The first particulate material and the second particulate material can react to form a solid in a period of time, and the third particulate material can solidify in a longer period of time. In another embodiment, the mixture of the plurality of particles may also include a filler. In another embodiment, the first particulate material is a phosphate. In another embodiment, the second particulate material is an alkaline oxide. In yet another embodiment, the first particulate material is a plaster. In another embodiment, the second particulate material is an accelerator. In yet another embodiment, the third particulate material is an adhesive.
  • [0015]
    Another aspect of the invention is directed to a compound used in three dimensional printing. The compound comprises a first particulate material, a second particulate material, and a third particulate, wherein the first particulate material and the second particulate material can react to form a solid in a period of time, and the third particulate material can solidify in a longer period of time. In another embodiment, the compound may also include a filler. In another embodiment, the first particulate material is a phosphate. In another embodiment, the second particulate material is an alkaline oxide. In yet another embodiment, the first particulate material is a plaster. In another embodiment, the second particulate material is an accelerator. In yet another embodiment, the third particulate material is an adhesive.
  • [0016]
    Another aspect of the invention is directed to a method of three-dimensional printing, comprising providing a layer of a dry particulate material comprising a first particulate material, a second particulate material, and a third particulate material and dispensing a fluid onto a region of the first layer. The fluid causes a reaction between the first and second particulate materials to occur, the reaction causing a solidified material to form in the region, and causes the third particulate material to solidify in the region. The reaction between the first and second particulate materials occurs in a period of time, and the third particulate material solidifies in a longer period of time. In another embodiment, the layer of dry particulate material may also include a filler. In another embodiment, the first particulate material is a phosphate. In another embodiment, the second particulate material is an alkaline oxide. In yet another embodiment, the first particulate material is a plaster. In another embodiment, the second particulate material is an accelerator. In yet another embodiment, the third particulate material is an adhesive.
  • [0017]
    Another aspect of the invention is directed to a mixture of solids used in three dimensional printing that, when contacted by a fluid, undergoes a first solidification reaction occurring at a first rate, and simultaneously undergoes a second solidification reaction occurring at a second rate slower than the first rate.
  • [0018]
    Other advantages, novel features, and objects of the invention will become apparent from the following detailed description of non-limiting embodiments of the invention when considered in conjunction with the accompanying drawings, which are schematic and which are not intended to be drawn to scale. In the figures, each identical or nearly identical component that is illustrated in various figures typically is represented by a single numeral. For purposes of clarity, not every component is labeled in every figure, nor is every component of each embodiment of the invention shown where illustration is not necessary to allow those of ordinary skill in the art to understand the invention. In cases where the present specification and a document incorporated by reference include conflicting disclosure, the present specification shall control.
  • BRIEF DESCRIPTION OF THE DRAWINGS
  • [0019]
    Preferred non limiting embodiments of the present invention will be described by way of example with reference to the accompanying drawings, in which:
  • [0020]
    FIG. 1 illustrates schematically a first layer of a mixture of particulate material of the invention deposited onto a downwardly movable surface on which an article is to built, before any fluid has been delivered;
  • [0021]
    FIG. 2 illustrates schematically an ink-jet nozzle delivering a fluid to a portion of the layer of particulate material of FIG. 1 in a predetermined pattern;
  • [0022]
    FIG. 3 illustrates schematically a view of a fmal article made from a series of steps illustrated in FIG. 2 enclosed in the container while it is still immersed in the loose unactivated particles;
  • [0023]
    FIG. 4 illustrates schematically a view of the final article from FIG. 3.
  • [0024]
    FIG. 5 illustrates schematically a cross-sectional view of a mold, including a support structure, for fabricating a casting.
  • DETAILED DESCRIPTION
  • [0025]
    The present invention relates to a Three Dimensional Printing material system useful, among other things, for preparing molds for casting, such as molds for metal casting. A large number of metal castings are made by pouring molten metal into a ceramic mold. For sand casting, the mold may be made of sand held together with binders. For investment casting, the mold may be made of refractories, such a alumina powder, held together by silica.
  • [0026]
    Molds prepared for casting should be sufficiently strong to withstand pouring of a molten material, such as metal, into a mold cavity. However, the mold should also be able to break during the cooling process, or be broken after the cooling process, to allow removal of the molded product.
  • [0027]
    In a Three Dimensional Printing material system, it is desired to have good depowderablility, sufficient strength, and a quick solidification mechanism when preparing a mold or an appearance model. As used herein, the term ‘depowderability” is defined as the ability to clean loose powder from a printed article after it has solidified. While the exemplary embodiments described herein are particularly advantageous for molds because of their strength, heat resistance and other characteristics, they can also be used to make appearance models and other articles.
  • [0028]
    The present invention relates to a Three Dimensional Printing material system comprising a mixture of a first particulate material, a second particulate material, a third particulate material, and a filler. A fluid causes the first particulate material and the second particulate material to react to form a solid in a first period of time, and causes the third particulate material to solidify in a second period of time that is longer than the first period of time. The reaction between the first particulate material and the second particulate material provides initial strength to the printed part during and after the printing process and may promote high accuracy, allow for a shorter time from the end of the print stage to handling and may reduce or eliminate part deformation. Solidification of the third particulate material provides strength to the final product. As used herein, the term “solid” is intended to mean a substance that has a definite volume and shape and resists forces that tend to alter its volume or shape, as well as to include solid-like substances, such as gels. The present invention also relates to a method of use for such a materials system, and to an article made by the method of the invention.
  • [0029]
    Referring now to FIG. 1, a schematic representation of a printing method using the materials system of the present invention is presented. According to the method, a layer or film of particulate material 20 is applied on a downwardly movable surface 22 of a container 24. The layer or film of particulate material can be formed in any manner, and preferably is applied using a counter-roller. The particulate material applied to the surface includes a first particulate material, a second particulate material, a third particulate material, and a filler. As used herein, “filler” is meant to define an inert material that is solid prior to application of the fluid, which is substantially insoluble in the fluid, and which gives structure to the final article. The first and second particulate materials react in the presence of a fluid to provide initial bond strength to the part being built, while the third particulate material solidifies in a longer period of time to provide final part strength.
  • [0030]
    For purposes of the present invention, “particulate material” is meant to define any dry material containing significant amounts of particulate material. The particulate material may be soluble in, or interact with the fluid material, or any portion thereof, depending upon the particular embodiment of the invention that is being practiced. For example, in certain embodiments, it may be desirable that the particulate material dissolve in the fluid material.
  • [0031]
    Generally, the size of the particles in the particulate material is limited by the thickness of the layers to be printed. That is, the particles are preferably approximately smaller than the thickness of the layers to be printed. The particulate materials may have any regular or irregular shape. Using smaller particles may provide advantages such as smaller feature size, the ability to use thinner layers, and the ability to reduce what is known in the art as a “stair stepping” effect. In preferred embodiments, the material systems include particulate material having particles with a mean diameter ranging from about 1 μm to about 300 μm, preferably ranging from about 2 μm to about 250 μm, more preferably ranging from about 10 μm to about 100 μm, and more preferably ranging from about 10 μm to about 50 μm.
  • [0032]
    The particulate material may include impurities and/or inert particles. The inert particles or any portion of the particulate material can comprise granular, powdered or fibrous materials. Classes of inert particles include a polymer, a ceramic, a metal, an organic material, an inorganic material, a mineral, clay and a salt.
  • [0033]
    Choosing a suitable particulate material for the material systems of the present invention involves various qualitative evaluations, which may easily be accomplished through routine experimentation by those of ordinary skill in the art. First, a small mound of particulate material is formed, a small depression is formed in the mound, and a small amount of fluid is placed in the depression. Visual observations are made regarding, among other things, the rate at which the fluid diffuses into the particulate material, the viscosity of the particulate material introduction of the fluid, and whether a membrane is formed around the fluid. Next, line testing is performed by filling a syringe filled with fluid and strafing the mounds of particulate material. After a period of about 24 hours, the mounds of particulate material are examined. Those in which pebbles of particulate material have formed are suitable, as it means that the particulate material and fluid react more quickly than the fluid can evaporate or diffuse into the surrounding dry powder. Those in which both pebbles and rods of hardened material have formed are the yet more suitable, indicating that the rate at which the fluid and particulate material harden is greater than the rate at which fluid evaporates or diffuses into the surrounding dry powder. In some instances, the rods of hardened material will shrink, indicating that the particulate material may give rise to problems with distortions. As described above, various additives may be included in the particulate material and/or fluid to accelerate the rate at which the particulate material hardens.
  • [0034]
    The particulate material may also be evaluated to determine the ease of spreading. Simple test parts may also be formed to determine, inter alias, the flexural strength, the distortion, the rate of hardening, the optimum layer thickness, and the optimum ratio of fluid to particulate material. Material systems suitable for use in the three-dimensional printing method include those hardening with minimal distortion, in addition to relatively high flexural strength. Hardened products with high flexural strength values may not be suitable for use in the three-dimensional printing method, if distortions compromise the accuracy of the final printed articles; this is especially applicable where relatively fine features are desired.
  • [0035]
    After a material has been identified as a potential material through line testing, the formula may be further developed by printing test patterns on a three dimensional printer. The strength, accuracy, and degree of difficulty in handling may all be characterized with a set of test parts (e.g., breaking bars for strength and gauge blocks for accuracy). These tests may be repeated as much as necessary, and powder formulas are iterated until optimum characteristics are obtained.
  • [0036]
    According to aspects of embodiments of the present invention, an additional criterion for selecting the particulate materials are the relative rates of reaction and/or solidification in the presence of a fluid. The first particulate material and the second particulate material are selected to react and solidify in the presence of the fluid in a period of time shorter than the solidification of the third particulate material in the presence of the fluid. Solidification of the reaction product of the first and second particulate materials in the presence of the fluid could occur within about 20 minutes. In another embodiment, the first particulate material and the second particulate material react to form a solid within about 10 minutes, preferably within about 5 minutes, more preferably within about 2 minutes, and most preferably within about 1 minute of application of the fluid. The solidification of the third particulate material occurs at a time longer than the reaction between the first particulate material and the second particulate material. In one embodiment, the third particulate material solidifies in a time ranging from about 10 minutes to about 2 hours or more. The absolute period of time for the solidification of the first and second particulate materials and the absolute period of time for solidification of the third particulate material can each vary over a wide range, however, the period of time for solidification of the third particulate material will be at least longer than period of time for solidification of the first particulate material and the second particulate material.
  • [0037]
    In one embodiment, the first particulate material may be an acid and second particulate material may be a base that react with one another in the presence of a fluid. For example, the first particulate material may be a phosphate while the second particulate material may be an alkaline oxide, and/or an alkaline hydroxide. When an aqueous fluid is printed on a powder that contains these materials, the phosphate dissolves and acts on the alkaline oxide and/or an alkaline hydroxide to form a cement.
  • [0038]
    The phosphates used in the embodiments of the invention include a salt of an oxygen acid of phosphorus including salts of phosphoric acids such as orthophosphoric acid, polyphosphoric acid, pyrophosphoric acid, and metaphosphoric acid.
  • [0039]
    As used herein, the term “phosphate” is generic and includes both crystalline and amorphous inorganic phosphates. Further, “phosphate” includes, but is not limited to, orthophosphates and condensed phosphates. Orthophosphates are compounds having a monomeric tetrahedral ion unit (PO4)3−. Typical orthophosphates include sodium orthophosphates, such as, monosodium phosphate, disodium phosphate, trisodium phosphate, potassium orthophosphates and ammonium orthophosphates. Phosphates are further described in U.S. Pat. No. 6,299,677 to Johnson et al. and incorporated by reference in its entirety for all purposes.
  • [0040]
    Examples of acid phosphates that may be used in embodiments of the invention include, but are not limited to, monoammonium phosphate; sodium aluminum phosphate, acidic; monocalcium phosphate, anhydrous; monopotassium phosphate; monosodium phosphate; and aluminum acid phosphate. Examples of acid polyphosphates that may be used in embodiments of the invention include, but are not limited to, sodium tripolyphosphate; sodium hexametaphosphate; sodium polyphosphate, anhydrous; and ammonium polyphosphate. Examples of acid pyrophosphates that may be used in embodiments of the invention include, but are not limited to, sodium acid pyrophosphate; tetrasodium pyrophosphate; tetrapotassium pyrophosphate. Examples of other phosphates that may be used in embodiments of the invention include, but are not limited to, diammonium phosphate; dipotassium phosphate; disodium phosphate; monocalcium phosphate, monhydrate; dicalcium phosphate, dihydrate; dicalcium phosphate, anhydrous; tricalcium phosphate; disodium phosphate; and tripotassium phosphate. In a preferred embodiment, the phosphate is a phosphate salt, such as, monocalcium phosphate, anhydrous; sodium aluminum phosphate, acidic; aluminum acid phosphate; monoammonium phosphate; monopotassium phosphate; and combinations thereof.
  • [0041]
    Alkaline oxides that may be used as the second particulate material include, but are not limited to, zinc oxide; magnesium oxide; calcium oxide; copper oxide; beryllium oxide; bismuth oxide; cadmium oxide; tin oxide; red lead oxide; and combinations thereof. Examples of alkaline hydroxides that may be used as the second particulate material include, but are not limited to, magnesium hydroxide, beryllium dihydroxide, cobalt trihydroxide, and combinations thereof. In one embodiment, the second particulate material is an alkaline oxide. In a preferred embodiment, the alkaline oxide is magnesium oxide. Magnesium oxide may react with phosphate compounds to form magnesium phosphate cement. In one embodiment, the ratio of magnesium oxide and acid phosphate salt may be varied to accommodate a variety of resin, filler, and binder chemistries.
  • [0042]
    In another embodiment, magnesium oxide may react with sulfate containing compounds to form magnesium oxysulfate cement, or react with chloride containing compounds to form magnesium oxychloride cement. In another embodiment, zinc oxide may react with sulfate containing compounds or chloride containing compounds. Examples of sulfate containing compounds include, but are not limited to, magnesium sulfate and zinc sulfate. Examples of chloride containing compounds include, but are not limited to, magnesium chloride, zinc chloride, and calcium chloride.
  • [0043]
    In another embodiment, the first particulate material may be plaster, and the second particulate material may be an accelerator. Plaster is frequently called “Plaster of Paris,” a name derived from the earths of Paris and its surrounding regions, which contain an abundance of the mineral gypsum, from which Plaster of Paris is manufactured. Plaster is also referred to by many other names, including, but not limited to, sulphate of lime, semihydrate of calcium sulfate, casting plaster, gypsum plaster, hydrated sulphate of lime, hydrated calcium sulphate, and dental plaster, as well as a variety of trade names. The term “plaster,” as used herein, is meant to define any variety of material including a substantial amount of CaSO4.½H2O that is in powder form prior to the application of an aqueous fluid. The terms “hydrated plaster” and “set plaster” are used interchangeably herein, and are meant to include any variety of plaster that includes a substantial amount of CaSO4.2H2O after setting, or rehydration. Many varieties of plaster are commercially available, varying, for example, in structural strength, the time required for setting, and in volume changes that occur during the setting. Typically, commercially available plasters include other ingredients such as, but not limited to, silica, powdered limestone, starch, Terra Alba, and lime. Examples of commercially available plaster materials that may be suitable for the embodiments of the present invention include, but are not limited to, white hydrocal cement, durabond 90, and drystone (each available from U.S. Gypsum, located in Chicago, Ill.), as well as most brands of casting plaster, molding plaster, and spackling compound.
  • [0044]
    An accelerator may be used as the second particulate material. “Accelerator,” as used herein, is meant to define any material that increases the rate at which plaster sets. Examples of ways to accelerate the rate of plaster include, but are not limited to, increasing the solubility of plaster in water, by providing additional nucleation sites for crystal formation or increasing the growth rate of crystals. Accelerators are generally used sparingly in conventional plaster processing, as they may adversely affect the strength characteristics of the plaster. However, accelerators are preferred in some embodiments of the present invention because they help produce a relatively quick set during printing and further processing. The potential adverse effect to the strength characteristics of the plaster is of less importance since the third particulate material is present to provide strength to the fmal part. Suitable accelerators include, but are not limited to, Terra Alba, potassium sulfate, barium sulfate, ammonium sulfate, sodium chloride, under calcined-plaster, alum, potassium alum, lime, calcined lime, and combinations thereof. Terra Alba, which is raw ground gypsum, is a preferred accelerator, and works by providing additional nucleation sites for gypsum crystal formation. Another preferred accelerator is potassium sulfate, which is thought to work by increasing the solubility of the plaster in the water. Both Terra Alba and potassium sulfate also increase the final strength of the article. In one embodiment, at least one accelerator is preferably used as a second particulate material in order to increase the rate at which the plaster sets. Plaster chemistry is further described in U.S. patent application Ser. No. 09/832,309 filed Apr. 10, 2001 which is a continuation of U.S. patent application Ser. No. 09/182,295 filed Oct. 29, 1998, and is incorporated herein by reference in its entirety for all purposes. The third particulate material of the embodiments of the invention reacts in the presence of an fluid to solidify at a rate slower than that of the reaction between the first particulate material and the second particulate material, and imparts strength to the final part. In one embodiment, the third particulate material is an adhesive. In another embodiment, the third particulate material is a filler coated with an adhesive.
  • [0045]
    The adhesive is a compound selected for the characteristics of high solubility in the fluid, low solution viscosity, low hygroscopicity, and high bonding strength. The adhesive should be highly soluble in the fluid in order ensure that it is incorporated rapidly and completely into the fluid. Low solution viscosity is preferred to ensure that once dissolved in the fluid, the solution migrates quickly to sites in the powder bed to adhesively bond together the reinforcing materials. The adhesive is preferably milled as finely as possible prior to admixture with the filler and/or prior to coating the filler particles in order to increase the available surface area, enhancing dissolution in the solvent, without being so fine as to cause “caking,” an undesirable article characteristic. Typical adhesive particle grain sizes are about 10-40 μm. Low hygroscopicity of the adhesive avoids absorption of excessive moisture from the air and evaporating fluid in printed regions of the powder bed which causes “caking”, in which unactivated powder spuriously adheres to the outside surface of the part, resulting in poor surface definition.
  • [0046]
    Water-soluble compounds are preferred for the adhesive in embodiments of the present invention, although other compounds can be used. Compounds suitable for use as the adhesive in embodiments of the present invention may be selected from the following non-limiting list: water-soluble polymers, carbohydrates, sugars, sugar alcohols, proteins, and some inorganic compounds. Water-soluble polymers with low molecular weights dissolve more quickly because smaller molecules diffuse more rapidly in solution. Suitable water-soluble polymers include but are not limited to, polyethylene glycol, sodium polyacrylate, polyacrylic acid, polyvinyl alcohol, polyvinyl pyrrolidone, sodium polyacrylate copolymer with maleic acid, polyvinyl alcohol copolymer with polyvinyl acetate, and polyvinyl pyrrolidone copolymer with vinyl acetate, a copolymer of octylacrylamide/acrylate/butylaminoethyl methacrylate, polyethylene oxide, sodium polystyrene sulfonate, polyacrylic acid, polymethacrylic acid, copolymers of polyacrylic acid and methacrylic acid with maleic acid, and alkali salts thereof, maltodextrine, hydrolyzed gelatin, sugar, polymethacrylic acid, polyvinyl sulfonic acid, sulfonated polyester, poly(2-ethyl-2-oxazoline), polymers incorporating maleic acid functionalities, and combinations thereof. Carbohydrates include, but are not limited to, acacia gum, locust bean gum, pregelatinized starch, acid-modified starch, hydrolyzed starch, sodium carboxymethylcellulose, sodium alginate and hydroxypropyl cellulose. Suitable sugars and sugar alcohols include sucrose, dextrose, fructose, lactose, polydextrose, sorbitol and xylitol. Organic compounds including organic acids and proteins can also be used, including citric acid, succinic acid, polyacrylic acid, gelatin, rabbit-skin glue, soy protein, and urea. Inorganic compounds include plaster, bentonite, sodium silicate and salt.
  • [0047]
    In another embodiment, a mixture of solid material is contacted by a fluid, and undergoes a first solidification beginning with the fluid contact and occurring at a first rate, and also undergoes a second solidification reaction beginning with the fluid contact and occurring at a second rate slower than the first rate. As used herein, the term “solid material” includes particulate material, aggregates, and the like. In one embodiment of the invention, a solid material may include more than one type of material, such as, a particulate material having a coating that is activated by the fluid causing a solidification reaction to occur within the solid material and among adjacent solid material. As used herein, the term “solidification reaction” is defined as any chemical, thermal, or physical process wherein free flowing solid material are hardened, bonded, or firmly fixed in relation to other adjacent solids.
  • [0048]
    In one embodiment, the mixture may be a mixture of two solid materials, wherein one of the solid materials is present in excess of a quantity that will react with the other solid material. In this embodiment, when contacted by a fluid, the two solids materials react and solidify in a first period of time, and the excess of one of the solid materials left over from the reaction with the other solid material reacts when contacted by a fluid in a second period of time that is longer than the first period of time. For example, the mixture may comprise an alkaline oxide, such as magnesium oxide, and at least one of polyacrylic acid, polymethacrylic acid, copolymers of polyacrylic acid and methacrylic acid with maleic acid, and alkali salts thereof. In the presence of a fluid, the alkaline oxide reacts with a portion of the at least one of polyacrylic acid, polymethacrylic acid, citric acid, succinic acid, malic acid, copolymers of polyacrylic acid and methacrylic acid with maleic acid, and alkali salts thereof to form a solid. The remaining portion of the at least one of polyacrylic acid, polymethacrylic acid, citric acid, succinic acid, malic acid, copolymers of polyacrylic acid and methacrylic acid with maleic acid, and alkali salts thereof left over from the reaction with the alkaline oxide may then solidify in the presence of a fluid in a longer period of time.
  • [0049]
    In another embodiment, the mixture may comprise two solids, wherein one solid material solidifies in the presence of a fluid in one period of time, while the other particulate material solidifies in the presence of a fluid in a second period of time that is longer than the first period of time.
  • [0050]
    In another embodiment, the mixture may comprise three solid materials, wherein a first and second solid material react in the presence of a fluid to form a solid in one period of time, and the third solid material solidifies in the presence of a fluid in a longer period of time. In an alternative embodiment, a first solid material may solidify in the presence of a fluid in one period of time, and a second solid material and third solid material may react to form a solid in the presence of a fluid in a second period of time that is longer than the first period of time.
  • [0051]
    In another embodiment, the mixture may comprise a first coated particulate material and a second particulate material. In one embodiment, the first coated particulate material reacts to form a solid in one period of time when contacted by a fluid and the second particulate material solidifies when contacted by a fluid in longer period of time. In another embodiment, a first coated particulate material reacts to form a solid in one period of time when contacted by a fluid and a second particulate material solidifies when contacted by a fluid in a shorter period of time. In another embodiment, one or more particulate material may be encapsulated, or present in an aggregate.
  • [0052]
    The fluid in embodiments of the present invention is selected to comport with the degree of solubility required for the various particulate components of the mixture, as described above. The fluid comprises a solvent in which the third particulate material and at least one of the first particulate material and the second particulate material are active, preferably soluble, and may include processing aids such as a humectant, a flowrate enhancer, and a dye. An ideal solvent is one in which the third particulate material and at least one of the first particulate material, the second particulate material, and the third particulate material is highly soluble, and in which the filler is insoluble or substantially less soluble. The fluid can be aqueous or non-aqueous. In a preferred embodiment, an aqueous fluid comprises at least one cosolvent. Suitable solvents and cosolvents may be selected from the following non-limiting list: water; methyl alcohol; ethyl alcohol; isopropyl alcohol; acetone; methylene chloride; acetic acid; ethyl acetoacetate; dimethylsulfoxide; n-methyl pyrrolidone; 2-amino-2-methyl-1-propanol; 1-amino-2-propanol; 2-dimethylamino-2-methyl-1-propanol; N,N-diethylethanolamine; N-methyldiethanolamine; N,N-dimethylethanolamine; triethanolamine; 2-aminoethanol; 1-[bis[3-(dimethylamino)propyl]amino]-2-propanol; 3-amino-1-propanol; 2-(2-aminoethylamino)ethanol; tris(hydroxymethyl)aminomethane; 2-amino-2-ethyl-1,3-propanediol; 2-amino-2-methyl-1,3-propanediol; diethanolamine; 1,3-bis(dimethylamino)-2-propanol; and combinations thereof. Other polar organic compounds will be obvious to one skilled in the art. In a preferred embodiment, the fluid is an aqueous solution of 2-amino-2-methyl-1-propanol, with isopropanol, ethanol, or a combination of both.
  • [0053]
    The filler in embodiments of the present invention is a compound selected for the characteristics of insolubility, or extremely low solubility in the fluid, rapid wetting, low hygroscopicity, and high bonding strength. The filler provides mechanical structure to the hardened composition. Sparingly soluble filler material may be used, but insoluble filler material is preferred. The filler particles become adhesively bonded together when the first particulate material and the second particulate material interact upon application of the fluid. The filler particles are further bonded together when the third particulate material dries/hardens after the fluid has been applied. Preferably, the filler includes a distribution of particle grain sizes, ranging from the practical maximum of about 250-300 μm downward, to the practical minimum of about 1 μm. Large grain sizes appear to improve the final article quality by forming large pores in the powder through which the fluid can migrate rapidly, permitting production of a more homogeneous material. Smaller grain sizes serve to reinforce article strength.
  • [0054]
    Compounds suitable for use as the filler in embodiments of the present invention may be selected from the same general groups from which the third particulate material is selected, provided that the solubility, hygroscopicity and bonding strength criteria described above are met. Examples of fillers include, but are not limited to, limestone, olivine, zircon, alumina, staurolite, and fused silica. In one embodiment, the filler may be a granular refractory particulate, including, but not limited to, limestone, staurolite, silica sand, zircon sand, olivine sand, chromite sand, magnesite, alumina silicate, calcium silicate, fused silica, calcium phosphate, rutile, bentonite, montmorillonite, glass, chamotte, fireclay, and mixtures thereof. In a preferred embodiment, the filler is olivine, a mineral used for foundry sand ((Mg—Fe)2SiO4) that is low in crystalline silica and possesses a low coefficient of thermal expansion. In another preferred embodiment, the filler is zircon (ZrSiO4).
  • [0055]
    Various processing aids may be added to the particulate material, the fluid, or both, including, but not limited to, accelerators, adhesives, flowrate enhancers, humectants, visible dyes, fiber, filler, and combinations thereof. Examples of these and other additives may be found in U.S. Pat. Nos. 5,902,441 to Bredt et al. and 6,416,850 to Bredt et al., both incorporated by reference in their entirety for all purposes
  • [0056]
    FIG. 2 is a schematic representation of an inkjet nozzle 28 delivering fluid 26 to a portion 30 of the layer or film 20 of the particulate mixture in a two-dimensional pattern. According to the method, the fluid 26 is delivered to the layer or film of particulate material in any predetermined two-dimensional pattern (circular, in the figures, for purposes of illustration only), using any convenient mechanism, such as a Drop-On-Demand (hereinafter “DOD”) printhead driven by customized software which receives data from a computer-assisted-design hereinafter “CAD”) system, a process which is known in the art. The first portion 30 of the particulate mixture is by the fluid, causing the first particulate material and the second particulate material to adhere together and the third particulate material to adhere to form an essentially solid circular layer that becomes a cross-sectional portion of the final article. As used herein, “activates” is meant to define a change in state from essentially inert to adhesive. When the fluid initially comes into contact with the particulate mixture, it immediately flows outward (on the microscopic scale) from the point of impact by capillary action, dissolving the adhesive within the first few seconds. A droplet of fluid, typically having a volume of about 100 μl, may spread to a surface area of about 100 μm once it comes into contact with the particulate mixture. As the solvent dissolves the third particulate material and at least one of the first particulate material and second particulate material, the fluid viscosity increases dramatically, arresting further migration of the fluid from the initial point of impact. Within a few minutes, the fluid with dissolved particulate material therein infiltrates the less soluble and slightly porous particles, forming bonds between the filler particles. The fluid is capable of bonding together the particulate mixture in an amount that is several times the mass of a droplet of the fluid. As volatile components of the fluid evaporate, the adhesives harden, joining the filler into a rigid structure, which becomes a cross-sectional portion of the finished article.
  • [0057]
    Any unactivated particulate mixture 32 that was not exposed to the fluid remains loose and free-flowing on the movable surface. Preferably, the unactivated particulate mixture is left in place until formation of the final article is complete. Leaving the unactivated, loose particulate mixture in place ensures that the article is supported during processing, allowing features such as overhangs, undercuts, and cavities (not illustrated, but conventional) to be defined without using support structures. After formation of the first cross-sectional portion of the final article, the movable surface is indexed downward.
  • [0058]
    Using, for example, a counter-rolling mechanism, a second film or layer of the particulate mixture is then applied over the first, covering both the rigid first cross-sectional portion, and any loose particulate mixture by which it is surrounded. A second application of fluid follows in the manner described above, dissolving the adhesive and forming adhesive bonds between a portion of the previous cross-sectional portion, the filler, and, optionally, fiber of the second layer, and hardening to form a second rigid cross-sectional portion added to the first rigid cross-sectional portion of the final article. The movable surface is again indexed downward.
  • [0059]
    Applying a layer of particulate mixture, including the adhesive, applying the fluid, and indexing the movable surface downward are repeated until the final article is completed. FIG. 3 is a schematic representation of the final cylindrical article after it has been completely formed. At the end of the process, only the top surface 34 of a final article 38 is visible in the container. The final article is preferably completely immersed in a bed 36 of unactivated particulate material. Alternatively, those skilled in this art would know how to build an article in layers upward from an immovable platform, by successively depositing, smoothing and printing a series of such layers.
  • [0060]
    FIG. 4 is a schematic representation of the final cylindrical article 38. The unactivated particulate material is preferably removed by blown air or a vacuum. After removal of the unactivated particulate material from the final article 38, post-processing treatment may be performed, including cleaning, infiltration with stabilizing materials, painting, etc.
  • [0061]
    FIG. 5 illustrates a mold prepared using the three-dimensional printing techniques of on embodiment of the present invention. Mold 40 comprises an inner shell 42, an outer shell 44, and supports 46 to provide added strength to the inner shell during the casting process. After three-dimensional printing is completed, unactivated particulate material is removed from cavity 48, thus providing a casting surface. Unactivated particulate material may, but need not be, removed from interstitial spaces 50. Unactivated particulate material remaining in the interstitial spaces may provide additional strength to the inner shell during subsequent casting.
  • [0062]
    Embodiments of the present invention is further illustrated by the following Examples which in no way should be construed as further limiting. The following representative formulas are directed to preparing molds for investment casting.
  • [0000]
    Particulate Formulation I
  • [0000]
    67% Olivine sand (−140 mesh)
  • [0000]
    • 29.6% Plaster
    • 3% PVA
    • 0.3% Terra alba
    • 0.1% K2SO4.
  • [0067]
    In Formulation I, Olivine is a mineral used for foundry sand ((Mg—Fe)2 SiO4) that is low in crystalline silica and possesses a low coefficient of thermal expansion. Olivine sand (−140 mesh) is bonded with plaster (Hydrocal) and PVA, but the bond between PVA and olivine is sufficiently strong that much less resin is needed. The reduced organic content causes molds made with the formulation of Example II, to emit less smoke during casting. This improves the environmental conditions during casting, and leads to higher quality castings due to the formation of less gas bubbling. The mold resulting from this formulation is suitable for low-temperature casting, such as casting Aluminum, Magnesium and Zinc.
  • [0000]
    Fluid I
  • [0000]
    • 92.6% Water
    • 6.0% glycerol
    • 0.5% isopropanol
    • 0.5% polyvinyl pyrrolidone
    • 0.2% 2,4,7,9-tetramethyl-5-decyne-4,7-diol ethoxylate
    • 0.2% potassium sorbate
  • [0074]
    Fluid I is a preferred fluid for particulate formulation I.
  • [0075]
    Particulate Formulations II and III are intended for high temperature material casting such as for brass, cast iron, and steel. Because plaster decomposes at around 1200° C. and releases sulfur dioxide, it is not desirable to use it for high temperature casting.
  • [0000]
    Particulate Formulation II
  • [0000]
    • 83.9% Zircon
    • 2.5% octacrylamide/acrylatelbutylaminoethyl methacrylate copolymer
    • 1.5% Zinc oxide
    • 10% limestone
    • 1.28% MgO
    • 0.72% monocalcium phosphate, anhydrate
    • 0.1% ethylene glycol octyl/decyl diester
  • [0083]
    Magnesium phosphate cement forms bonds early in the curing process to resist the drying stresses and attendant part distortion. The active cement filler is formed by the combination of magnesium oxide with monocalcium phosphate, anhydrate. Any commercially available grade of magnesium oxide or monocalcium phosphate, anhydrate may be used. This material rapidly forms a gel that maintains the dimensional stability of the part while the octylacrylamide/acrylate/butylaminoethyl methacrylate copolymer, having a particle size of less than about 70 μm, dissolves and deposits itself into the pores of the granular solid, forming stronger bonds that support the material during handling up the casting stage. Zircon (ZrSiO4) having a 140 mesh particle size is a very refractory (foundry sand) filler that has a very low coefficient of thermal expansion. The remaining ingredients: Zinc oxide having a particle size of about 10 microns, limestone having a particle size of less than about 40 microns, and ethylene glycol octyl/decyl diester are added in order to control the flow of powder during spreading and printing. Any commercially available grade of ethylene glycol octyl/decyl diester may be used.
  • [0000]
    Particulate Formulation III
  • [0000]
    • 75.9% Olivine
    • 2.0% octacrylamide/acrylate/butylaminoethyl methacrylate copolymer
    • 2.4% ZnO
    • 15.9% fused silica (SiO2)
    • 2.2% MgO
    • 1.4% monocalcium phosphate, anhydrous
    • 0.18% ethylene glycol octyl/decyl diester
    • 0.02% sorbitan trioleate (SPAN 85)
  • [0092]
    In this formula, olivine replaces zircon as the refractory filler. Olivine has a slightly higher thermal expansion than zircon, but since it is lower density, the printed parts are lighter and easier to manipulate. The magnesium oxide/monocalcium phosphate cement enables parts to be built and removed from the machine rapidly, and placed in a drying oven to harden the organic copolymer to full strength. Zinc oxide and fused silica, having a particle size of about 200 mesh, are fine powdered additives. Ethylene glycol octyl/decyl diester and sorbitan trioleate are oily liquids that give the powder a small degree of cohesion, further improving the friction characteristics.
  • [0000]
    Fluid II
  • [0000]
    • 86.5% water
    • 10.0% isopropanol
    • 2.5% 2-amino-2-methyl-1-propanol
    • 1% 2,4,7,9-tetramethyl-5-decyne-4,7-diol ethoxylate
  • [0097]
    In Fluid II, the water component dissolves the phosphate allowing the phosphate to act on the magnesium oxide to form a cement. Fluid II includes 2-amino-2-methyl-1-propanol, an organic alkali that is compatible with the octylacrylonitrile/acrylate/butylaminoethyl methacrylate copolymer and dissolves the copolymer. Isopropanol and 2,4,7,9-tetramethyl-5-decyne-4,7-diol ethoxylate facilitate wetting of the fluid in the powder.
  • [0098]
    Further considerations when selecting the adhesive, filler and fiber depend on the desired properties of the fmal article. The fmal strength of the finished article depends largely on the quality of the adhesive contacts between the particles of the mixture, and the size of the empty pores that persist in the material after the adhesive has hardened; both of these factors vary with the grain size of the particulate material. In general, the mean size of the grains of particulate material is preferably not larger than the layer thickness. A distribution of grain sizes increases the packing density of the particulate material, which in turn increases both article strength and dimensional control.
  • [0099]
    The materials and method of the illustrative embodiments of the present invention present several advantages over prior Three Dimensional Printing methods. The particulate materials provide a relatively rapid binding reaction in addition to a relatively longer reaction time for preparing the fmal part. The additional rapid binding mechanism may provide high accuracy, allow for shorter printing and handling time and may reduce or eliminate part deformation. The materials used in embodiments of the present invention are relatively non-toxic and inexpensive. Because the binding particles are added directly to the particulate mixture, adhesive, particularly adhesive including high levels of suspended solids, need not be sprayed through the printhead. Instead, embodiments of the present invention involves spraying preferably an aqueous solvent, which overcomes problems such as clogging associated with prior art methods that involve spraying a binder to a layer of powder.
  • [0100]
    Those skilled in the art will readily appreciate that all parameters listed herein are meant to be exemplary and actual parameters depend upon the specific application for which the methods and materials of the present invention are used. It is, therefore, to be understood that the foregoing embodiments are presented by way of example only and that, within the scope of the appended claims and equivalents thereto, the invention can be practiced otherwise than as specifically described.
  • [0101]
    While several embodiments of the invention have been described and illustrated herein, those of ordinary skill in the art will readily envision a variety of other means and structures for performing the functions and/or obtaining the results or advantages described herein, and each of such variations or modifications is deemed to be within the scope of the present invention. More generally, those skilled in the art would readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that actual parameters, dimensions, materials, and configurations will depend upon specific applications for which the teachings of the present invention are used. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. It is, therefore, to be understood that the foregoing embodiments are presented by way of example only and that, within the scope of the appended claims and equivalents thereto, the invention may be practiced otherwise than as specifically described. The present invention is directed to each individual feature, system, material and/or method described herein. In addition, any combination of two or more such features, systems, materials and/or methods, if such features, systems, materials and/or methods are not mutually inconsistent, is included within the scope of the present invention.
  • [0102]
    In the claims (as well as in the specification above), all transitional phrases such as “comprising”, “including”, “carrying”, “having”, “containing”, “involving”, and the like are to be understood to be open-ended, i.e. to mean including but not limited to. Only the transitional phrases “consisting of” and “consisting essentially of” shall be closed or semi-closed transitional phrases, respectively, as set forth in the United States Patent Office Manual of Patent Examining Procedures, section 2111.03.
Citas de patentes
Patente citada Fecha de presentación Fecha de publicación Solicitante Título
US3297601 *13 Ago 196310 Ene 1967United States Gypsum CoSubstantially dry joint compound comprising calcium sulfate, polyvinyl acetate and starch
US3303147 *15 Ene 19637 Feb 1967Nat Gypsum CoDry powder for wallboard joint treatment
US3309328 *3 Jun 196414 Mar 1967Allied ChemHigh strength adhesive for building materials
US3870538 *7 May 197311 Mar 1975Nat Gypsum CoGypsum set accelerator
US3930872 *14 Nov 19736 Ene 1976Ashland Oil, Inc.Binder compositions
US3932923 *21 Oct 197420 Ene 1976Dynell Electronics CorporationMethod of generating and constructing three-dimensional bodies
US4078229 *27 Ene 19757 Mar 1978Swanson Wyn KThree dimensional systems
US4247508 *3 Dic 197927 Ene 1981Hico Western Products Co.Molding process
US4310996 *23 Abr 198019 Ene 1982General Electric Co.Cement reinforced gypsum foam with mineral wool
US4369025 *13 Jun 198018 Ene 1983Epsi Brevets Et Participations S.A.Apparatus for manufacturing elements by means of a hardenable binding agent to which a liquid is added
US4575330 *8 Ago 198411 Mar 1986Uvp, Inc.Apparatus for production of three-dimensional objects by stereolithography
US4649077 *20 May 198510 Mar 1987Adnovum AgHeat activatable multi-component sheet material & process for making same
US4801477 *29 Sep 198731 Ene 1989Fudim Efrem VMethod and apparatus for production of three-dimensional objects by photosolidification
US4996010 *18 Abr 198826 Feb 19913D Systems, Inc.Methods and apparatus for production of three-dimensional objects by stereolithography
US4996282 *8 Sep 198926 Feb 1991Desoto, Inc.Cationically curable polyurethane compositions having vinyl ether functionality
US4999143 *18 Abr 198812 Mar 19913D Systems, Inc.Methods and apparatus for production of three-dimensional objects by stereolithography
US5088047 *16 Oct 198911 Feb 1992Bynum David KAutomated manufacturing system using thin sections
US5089184 *18 Dic 198918 Feb 1992Mitsui Engineering And Shipbuilding Co., Ltd.Optical molding method
US5089185 *18 Dic 198918 Feb 1992Mitsui Engineering And Shipbuilding Co., Ltd.Optical molding method
US5094935 *26 Jun 199010 Mar 1992E. I. Dupont De Nemours And CompanyMethod and apparatus for fabricating three dimensional objects from photoformed precursor sheets
US5096491 *16 Jul 199017 Mar 1992Honshu Paper Co., Ltd.Aqueous starch slurry adhesive
US5096530 *28 Jun 199017 Mar 19923D Systems, Inc.Resin film recoating method and apparatus
US5176188 *14 Feb 19915 Ene 1993E. I. Du Pont De Nemours And CompanyInvestment casting method and pattern material comprising thermally-collapsible expanded microspheres
US5182055 *17 May 199126 Ene 19933D Systems, Inc.Method of making a three-dimensional object by stereolithography
US5182134 *28 Ene 199226 Ene 1993H. B. Fuller Licensing & Financing Inc.Radio frequency cure of thermoset-receptor compositions
US5182715 *22 Ene 199226 Ene 19933D Systems, Inc.Rapid and accurate production of stereolighographic parts
US5183598 *4 Mar 19912 Feb 1993Dassault AviationProcess of and apparatus for making three-dimensional objects
US5184307 *31 Mar 19892 Feb 19933D Systems, Inc.Method and apparatus for production of high resolution three-dimensional objects by stereolithography
US5192469 *30 Oct 19909 Mar 19933D Systems, Inc.Simultaneous multiple layer curing in stereolithography
US5192559 *3 Dic 19919 Mar 19933D Systems, Inc.Apparatus for building three-dimensional objects with sheets
US5198159 *9 Oct 199030 Mar 1993Matsushita Electric Works, Ltd.Process of fabricating three-dimensional objects from a light curable resin liquid
US5275916 *17 Abr 19924 Ene 1994Fuji Photo Film Co., Ltd.Direct-image type lithographic printing plate precursor
US5278442 *15 Jul 199111 Ene 1994Prinz Fritz BElectronic packages and smart structures formed by thermal spray deposition
US5279665 *30 Oct 199118 Ene 1994Ashland Oil, Inc.Inorganic foundry binder systems and their uses
US5281789 *24 Jul 199225 Ene 1994Robert MerzMethod and apparatus for depositing molten metal
US5286573 *17 Sep 199215 Feb 1994Fritz PrinzMethod and support structures for creation of objects by layer deposition
US5287435 *23 Ago 199015 Feb 1994Cubital Ltd.Three dimensional modeling
US5289214 *27 Sep 199122 Feb 1994Cubital Ltd.Apparatus for information transfer including a dielectric element and generally non-imagewise charge service
US5296062 *25 Sep 199222 Mar 1994The Board Of Regents, The University Of Texas SystemMultiple material systems for selective beam sintering
US5296335 *22 Feb 199322 Mar 1994E-Systems, Inc.Method for manufacturing fiber-reinforced parts utilizing stereolithography tooling
US5382289 *17 Sep 199317 Ene 1995Ashland Oil, Inc.Inorganic foundry binder systems and their uses
US5382308 *21 Mar 199417 Ene 1995Board Of Regents, The University Of Texas SystemMultiple material systems for selective beam sintering
US5385772 *19 Feb 199131 Ene 1995Adco Products, Inc.Pressure-sensitive adhesive systems with filler
US5386500 *13 Abr 199231 Ene 1995Cubital Ltd.Three dimensional modeling apparatus
US5387380 *5 Jun 19927 Feb 1995Massachusetts Institute Of TechnologyThree-dimensional printing techniques
US5391072 *3 Feb 199221 Feb 1995E. I. Du Pont De Nemours And CompanySolid imaging apparatus having a semi-permeable film
US5391460 *12 Jul 199321 Feb 1995Hughes Aircraft CompanyResin composition and process for investment casting using stereolithography
US5393613 *3 Dic 199328 Feb 1995Microelectronics And Computer Technology CorporationComposition for three-dimensional metal fabrication using a laser
US5402351 *18 Ene 199428 Mar 1995International Business Machines CorporationModel generation system having closed-loop extrusion nozzle positioning
US5490882 *30 Nov 199213 Feb 1996Massachusetts Institute Of TechnologyProcess for removing loose powder particles from interior passages of a body
US5490962 *18 Oct 199313 Feb 1996Massachusetts Institute Of TechnologyPreparation of medical devices by solid free-form fabrication methods
US5491643 *4 Feb 199413 Feb 1996Stratasys, Inc.Method for optimizing parameters characteristic of an object developed in a rapid prototyping system
US5494618 *27 Jun 199427 Feb 1996Alliedsignal Inc.Increasing the useful range of cationic photoinitiators in stereolithography
US5495029 *4 Ago 199427 Feb 1996Ciba-Geigy Corporation(Meth)acrylates containing urethane groups
US5495328 *30 Nov 199327 Feb 19963D Systems, Inc.Apparatus and method for calibrating and normalizing a stereolithographic apparatus
US5498782 *8 Sep 199312 Mar 1996Union Carbide Chemicals & Plastics Technology CorporationDistortion control additives for ultraviolet-curable compositions
US5500069 *14 Abr 199419 Mar 1996Matsushita Electric Industrial Co., Ltd.Three dimensional object-forming method
US5501824 *8 Nov 199326 Mar 19963D Systems, Inc.Thermal stereolithography
US5591563 *30 Oct 19957 Ene 1997Takemoto Yushi Kabushiki KaishaPhotocurable resins for stereolithography and compositions containing same
US5593531 *9 Nov 199414 Ene 1997Texas Instruments IncorporatedSystem, method and process for fabrication of 3-dimensional objects by a static electrostatic imaging and lamination device
US5594652 *7 Jun 199514 Ene 1997Texas Instruments IncorporatedMethod and apparatus for the computer-controlled manufacture of three-dimensional objects from computer data
US5595597 *6 Mar 199621 Ene 1997Rhone-Poulenc ChimieProcess for producing phosphomagnesia cements having reduced sensitivity to water
US5595703 *10 Mar 199521 Ene 1997Materialise, Naamloze VennootschapMethod for supporting an object made by means of stereolithography or another rapid prototype production method
US5596504 *10 Abr 199521 Ene 1997Clemson UniversityApparatus and method for layered modeling of intended objects represented in STL format and adaptive slicing thereof
US5597520 *25 Abr 199428 Ene 1997Smalley; Dennis R.Simultaneous multiple layer curing in stereolithography
US5597589 *31 May 199428 Ene 1997Board Of Regents, The University Of Texas SystemApparatus for producing parts by selective sintering
US5598340 *7 Jun 199328 Ene 1997Laser 3DMethod of producing industrial components by the action of light on a polymerizable or crosslinkable liquid substance without requiring supports
US5599651 *21 Ago 19954 Feb 1997Ciba-Geigy Corporation(Cyclo)aliphatic epoxy compounds
US5603797 *5 Jun 199518 Feb 1997E-Systems, Inc.Flexible reinforced rubber part manufacturing process utilizing stereolithography tooling
US5605941 *12 Sep 199425 Feb 1997Steinmann; BettinaVinyl ether compounds having additional functional groups other than vinyl ether groups and the use thereof in the formulation of curable compositions
US5608814 *17 Nov 19944 Mar 1997General Electric CompanyMethod of dynamic thresholding for flaw detection in ultrasonic C-scan images
US5609812 *14 Sep 199311 Mar 19973D Systems, Inc.Method of making a three-dimensional object by stereolithography
US5610824 *25 Ene 199311 Mar 19973D Systems, Inc.Rapid and accurate production of stereolithographic parts
US5611883 *9 Ene 199518 Mar 1997Board Of Regents, The University Of Texas SystemJoining ceramics and attaching fasteners to ceramics by gas phase selective beam deposition
US5614075 *7 Jun 199525 Mar 1997Andre Sr.; Larry E.Method of incremental object fabrication
US5705116 *21 Jun 19956 Ene 1998Sitzmann; Eugene ValentineIncreasing the useful range of cationic photoinitiators in stereolithography
US5705117 *1 Mar 19966 Ene 1998Delco Electronics CorporaitonMethod of combining metal and ceramic inserts into stereolithography components
US5705316 *9 Nov 19956 Ene 1998Ciba Specialty Chemicals CorporationVinyl ether compounds having additional functional groups other than vinyl ether groups and the use thereof in the formulation of curable compositions
US5707578 *14 Jun 199613 Ene 1998Hach CompanyMethod for making mold inserts
US5707780 *7 Mar 199613 Ene 1998E. I. Du Pont De Nemours And CompanyPhotohardenable epoxy composition
US5711911 *7 Jun 199527 Ene 19983D Systems, Inc.Method of and apparatus for making a three-dimensional object by stereolithography
US5713410 *1 Jun 19953 Feb 1998Johnson & Johnson Professional, Inc.Bone prostheses with direct cast macrotextured surface regions and method for manufacturing the same
US5717599 *19 Oct 199410 Feb 1998Bpm Technology, Inc.Apparatus and method for dispensing build material to make a three-dimensional article
US5718757 *3 Dic 199617 Feb 1998Rhone-Poulenc ChimieBinding phase for phosphomagnesium cements and their use for the preparation of mortars
US5728345 *3 Mar 199517 Mar 1998General Motors CorporationMethod for making an electrode for electrical discharge machining by use of a stereolithography model
US5730817 *22 Abr 199624 Mar 1998Helisys, Inc.Laminated object manufacturing system
US5730925 *18 Abr 199624 Mar 1998Eos Gmbh Electro Optical SystemsMethod and apparatus for producing a three-dimensional object
US5731388 *7 Nov 199524 Mar 1998Takemoto Yushi Kabushiki KaishaPhotocurable resins for stereolithography and compositions containing same
US5870307 *7 Jun 19959 Feb 19993D Systems, Inc.Method and apparatus for production of high resolution three-dimensional objects by stereolithography
US6193922 *14 Abr 199827 Feb 2001Ingo EdererMethod for making a three-dimensional body
US6348679 *13 Ene 200019 Feb 2002Ameritherm, Inc.RF active compositions for use in adhesion, bonding and coating
US6989115 *8 May 200124 Ene 2006Z CorporationMethod and apparatus for prototyping a three-dimensional object
US20020016387 *30 May 20017 Feb 2002Jialin ShenMaterial system for use in three dimensional printing
US20040038009 *21 Ago 200226 Feb 2004Leyden Richard NoelWater-based material systems and methods for 3D printing
US20050001356 *2 Ago 20046 Ene 2005Minolta Co., Ltd.Apparatus for forming a three-dimensional product
US20050003189 *19 May 20046 Ene 2005Bredt James F.Thermoplastic powder material system for appearance models from 3D prinitng systems
US20050017394 *11 Jun 200427 Ene 2005Voxeljet GmbhMethods and systems for the manufacture of layered three-dimensional forms
US20070007698 *17 Ago 200411 Ene 2007Shojiro SanoMethod of producting three-dimensional model
US20070029698 *9 Sep 20048 Feb 2007Rynerson Michael LLayered manufactured articles having small-diameter fluid conduction vents and method of making same
Citada por
Patente citante Fecha de presentación Fecha de publicación Solicitante Título
US742433512 Jul 20069 Sep 2008Swift Lawrence WIdentification of terrestrial foliage location, type and height for scaled physical models
US779534924 May 200614 Sep 2010Z CorporationMaterial systems and methods of three-dimensional printing
US79059517 Dic 200715 Mar 2011Z CorporationThree dimensional printing material system and method using peroxide cure
US796862622 Feb 200828 Jun 2011Z CorporationThree dimensional printing material system and method using plasticizer-assisted sintering
US8105433 *13 Feb 200931 Ene 2012The University Of TokyoCement admixture, and cement composition and concrete containing the cement admixture
US815790828 Ene 201117 Abr 20123D Systems, Inc.Three dimensional printing material system and method using peroxide cure
US816799910 Ene 20081 May 20123D Systems, Inc.Three-dimensional printing material system with improved color, article performance, and ease of use
US8381795 *27 Ene 201226 Feb 2013General Electric CompanyApparatus for casting filaments
US845488515 May 20084 Jun 2013Corning IncorporatedMethod for making fused ceramic articles of near net shape
US85068622 Feb 201113 Ago 20133D Systems, Inc.Three dimensional printing material system and method using plasticizer-assisted sintering
US859059520 Jun 201226 Nov 2013General Electric CompanyCasting methods and apparatus
US866885226 Feb 201011 Mar 2014Tomita Pharmaceutical Co., Ltd.Powder for molding and method for producing molded article using the same
US20050059757 *25 Ago 200417 Mar 2005Z CorporationAbsorbent fillers for three-dimensional printing
US20050087902 *28 Oct 200328 Abr 2005Isaac FarrAlginate-based materials, methods of application thereof, and systems for using the alginate-based materials
US20070011982 *12 Jul 200618 Ene 2007Swift Lawrence WIdentification of terrestrial foliage location, type and height for scaled physical models
US20070013724 *12 Jul 200618 Ene 2007Swift Lawrence WBuilding of scaled physical models
US20070042327 *12 Jul 200622 Feb 2007Swift Lawrence WDetermination of scaling for scaled physical architectural models
US20080015947 *21 Dic 200617 Ene 2008Swift Lawrence WOnline ordering of architectural models
US20110132231 *13 Feb 20099 Jun 2011The University Of TokyoCement admixture, and cement composition and concrete containing the cement admixture
US20120247705 *27 Ene 20124 Oct 2012General Electric CompanyApparatus for casting filaments
CN105579161A *13 Ago 201411 May 2016艾克斯温有限责任公司Three-dimensional printed metal-casting molds and methods for making the same
WO2015023729A1 *13 Ago 201419 Feb 2015The Exone CompanyThree-dimensional printed metal-casting molds and methods for making the same
WO2016048341A1 *26 Sep 201431 Mar 2016Hewlett-Packard Development Company, L.P.Pastes for printing three-dimensional objects in additive manufacturing processes
Clasificaciones
Clasificación de EE.UU.106/690, 106/689, 106/691, 524/4, 106/683, 524/5
Clasificación internacionalC04B28/30, C04B28/34, C04B9/00, B27N3/02, C04B28/14, B29K105/00, C04B28/02, B29C41/02, C04B24/26, B29C67/00
Clasificación cooperativaB29C64/165, B33Y70/00, B33Y80/00, B28B7/465, B28B1/001, C04B28/30, C04B2111/00181, C04B28/34, C04B28/14
Clasificación europeaC04B28/30, C04B28/34, C04B28/14, B29C67/00R6
Eventos legales
FechaCódigoEventoDescripción
18 Jul 2006ASAssignment
Owner name: Z CORPORATION, MASSACHUSETTS
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:BREDT, JAMES F.;CLARK, SARAH L.;GILCHRIST, GRIETA;REEL/FRAME:017952/0539;SIGNING DATES FROM 20021202 TO 20030116