US20050189682A1

US20050189682A1 - Reverse thermal gels as support for rapid prototyping

Info

Publication number: US20050189682A1
Application number: US10/998,644
Authority: US
Inventors: Avraham Levy
Original assignee: Object Geometries Ltd
Current assignee: Object Geometries Ltd
Priority date: 2001-08-16
Filing date: 2004-11-30
Publication date: 2005-09-01
Also published as: US7368484B2; US20030107158A1; US20070032563A1; US6863859B2

Abstract

The present invention relates to novel polymeric compositions that exhibit Reverse Thermal Gelation (RTG) properties for use as Support Materials (SM) in the manufacture of three-dimentional objects. These polymers are Temperature Sensitive Poolymers that respond with a significant change of properties to a small change in temperature. Temperature Sensitive Polymers exhibit cloud point (CP) or lower critical solution temperature (LCST) in aqueous solutions. Water-soluble Temperature Sencitive Polymers are chosen to give low viscosity liquid at low temperature when dissolved in water and by that to permit easy dispensing at low temperature. Rising the temperature above their gelation temperature (T_gel) will result in solidification of the composition. At its gel position the material has favorable characteristics as a support and building material. The gel layers have the appropriate toughness and dimensional stability to support the model layers during the building process. After the building process is completed the gel can be cooled down to a temperature below its T_gelso the gel can liquefy and be removed easily by rinsing with a water.

Description

RELATED APPLICATIONS

This application claims priority from provisional application U.S. Ser. No. 60/312,490, filed 16 Aug. 2001, entitled “REVERSE THERMAL GELS AS SUPPORT FOR RAPID PROTOTYPING” which is incorporated in its entirety by reference herein.

FIELD OF THE INVENTION

Embodiments of the present invention relate to methods of using novel polymeric compositions as support and build materials for Rapid Prototyping (RP), Rapid Manufacturing (RM), and Rapid Tooling (RT) processes. These polymeric compositions exhibit Reverse Thermal Gelation (RTG) properties, i.e. low viscosoty at low temperature and high viscosity (or semi-solid) gels at higher temperatures.

BACKGROUND OF THE INVENTION

Rapid prototyping is a generic name of various technologies for producing three-dimentional models, usually from three-dimentional CAD (Computer Aided Design) data.
One such technology is known in the art as three-dimentional printing, in which layers descriptive of the model are produced from the CAD data, then a curable liquid material, usually a photopolymer, is dispensed and cured layer by layer by exposure to light.
One such technique is disclosed in U.S. application No. 09/412,618 assigned to the applicants of the present invention, filed Oct. 6, 1999, entitled “SYSTEM AND METHOD FOR THREE DIMENTIONAL MODEL PRINTING,” incorporated herein by reference.
According to certain embodiments described in Ser. No. 09/412,618, the model is produced from a building material (BM), which is a curable liquid photopolymer, dispensed by ink jet multi-nozzle heads. Simultaneously with the BM dispensing, a second set of ink jet heads dispenses Support Material (SM), which exhibit different properties from those of the BM.
Preferably, the SM is dispensed in locations where BM is absent, thus holding the liquid BM in place until being cured. At the conclusion of the model production, the SM is to be disposed without spoiling the model.
There are many techniques, known in the art, for SM removal, which depend on the material properties, Using wax, for instance, as SM, enables SM removing by raising the model temperature beyond the melting point of the SM.
Another known technique is stereolithography, in which use is made of a single curable materal in a container, curing selectively only those portions required in from the model, the uncured portions are used as support materials and are removed at a later stage. This technique is disclosed for example U.S. Pat. No. 5,779,967 to Hull.
Rapid prototyping (RP) techniques are known in the art as techniques used to produce models out of three-dimentional CAD data. In the same way, rapid tooling (RT) manufacturing techniques are generally used for rapid manufacturing of casting molds. Rapid manufacturing (RM) techniques are genrally used for direct manufacturing of finished ports.
In all of these prior art techniques the unnecessary part (i.e. the support, the mold or the core) should be disposed, leaving the other part intact. In these above-mentioned technoques, the materials used as SM do not exhibit the optimal combination of properties required, i.e. easy dispensing, toughness as supporting material, easy removal from the finished model and friendliness to the environment. Thus, there is a strong need in the art for new and better materials that can be used to support 3-dimentional objects during construction.

SUMMARY OF THE INVENTION

In the embodiment, the present invention provides a composition suitable for supporting and/or building a three-dimentional object, the composition comprising at list one Temperature Sensitive Polymer, and at least one surface-active agent, wherein the composition exhibits Reverse Thermal Gelation (RTG) properties.
Furthermore, in another embodiment, the present invention provides a method for building a three-dimentional object by three dimentional printing, the method comprising the steps of dispensing a building composition, comprising at least one Temperature Sensitive Polymer, wherein the building composition exhibits Reverse Thermal Gelation (RTG) properties and at least one surface-active agent; and gelating the building composition by increasing temperature to above gelation temperature, thereby constructing the three dimentional object.
Furthermore, in another embodiment, the present invention provides a method for supporting a three-dimentional object during construction, the method comprising the step of contacting the object with a support composition, comprising at least one Temperature Snesitive Poyner, wherein the support composition exhibits Reverse Thermal Gelation (RTG) properties and at least on surface-active agent; gelating the support composition by increasing temperature to above gelation temperature, thereby supporting the three dimentional object.
Furthermore, in another embodiment, the method further comprises the step of easy removing the support composition after construction of the object by cooling the support composition to a temperature below the gelation temperature.
Furthermore, in another embodiment, the construction comprises Rapid Prototyping (RP), Rapid Manufacturing (RM) or Rapid Tooling (RT).
In one embodiment, the construction comprises rapid tooling (RT), wherein the rapid tooling (RT) comprises building a casting mold with the support composition for holding the object, and building the object in the mold. In another embodiment, the method further comprises the step of easy removing the mold by cooling the support composition to a temperature below the gelation temperature.
In another embodiment, the composition comprises Rapid Manufacturing (RM), wherein the rapid manufacturing (RM) comprises direct manufacturing of finished parts.
In one embodiment, the Temperature Sensitive Polymer is a water-soluble Temperature Sensitive Polymers. In another embodiment, the water-soluble Temperature Sensitive Polymer is an ABA triblock oligomer, wherein A and B are oligomers. In another embodiment, A is a hydrophilic oligomer and B is a hydrophobic oligomer. In another embodiment, A is a hydrophobic oligomer and B is a hydrophilic oligomer. In another embodiment, A and B comprise aliphatic polyether and/or polyester units. In another embodiment, A is poly(ethylene oxide) and B is poly(propylene oxide).
In another embodiment, the water-soluble Temperature Sensitive Polymer is a multi blocks polymer of (ABA-X)_m, organized at random or repetitive configuration, wherein wherein A and B are oligomers, m is an integer of 1-30, and X is a chain extender. In one embodiment, X is selected from the group consisting of di, tri and poly isocyanates, di, try and poly carboxylic acids, diecyl halides, triphosgene or any combination thereof. In another embodoment, A is a hydrophilic oligomer and B is a hydrophobic oligomer. In another embodiment, A is a hydrophobic oligomer and B is a hydrophilic oligomer. In another embodiment, the multi block polymer of ABA is a polyurethane, a polycarbonate, a polyester or any combination thereof.
In another embodiment, the Temperature Sensitive Polymer is a poly (N-substituted (meth)acrylamide). In one embodiment, the poly (N-substituted (meth)acrylamide) is a poly (N-isopropyl (meth)acrylamides). In another embodiment, the Temperature Sensitive Polymer is apoly vinyl alcohol derivative, hydroxypropyl methylcellulose, ethyl hydroxyethyl cellulose (EHEC) or any combination thereof.
In another embodiment, the surface-active agent is capable of reducing the surface tension of the support and/or building compositionto about 30 dyno/cm. In another embodiment, the surface-active agent is a silicon surface-active agent additive, fluoro-based surface-active agent or any combination thereof.
Furthermore, in another embodiment, the support and/or building composition further comprise at least one photo curable reactive component, at least one photo-initiator, and at least one stabilizer. In ane embodiment, the method further comprises the step of curing the support and/or building composition, thereby increasing the strength of the support and/or building composition. In one embodiment, the curable reactive component is a (meth)acrylic component. In another embodoment, the (meth)acrylic component is a (meth)acrylic monomer, a (meth)acrylic oligomer, or a combination thereof. In another embodiment, the (meth)acrylic component is a polyethylene glycol mono or di (meth)acrylated, polymer triacrylate or any combination thereof. In another embodiment, the reactive component is a water miscible component that is, after irradiation or curing, capable of dissolving or swelling upon exposure to water or to an alkaline or acidic water solution. In another embodiment, the water miscible component is an acryloyl morpholine, (meth)acrylated urethane olligomer derivative of polyethylene glycol, a partially (meth)acrylated polyol oligomer, an (meth)acrylated oligomer having hydrophilic substituents or any combination thereof. In another embodiment, the hydrophilic substituents are acidic substituents, amino substituents, hydroxy substituents or any combination thereof. In another embodiment, the (meth)acrylic component is beta-carboxyethyl acrylate. In one embodiment, the reactive component is a molecule having one or more vinyl ether substituents. In another embodiment, the vinyl ether substituent is hydroxy-butyl vinyl ether.
In another embodiment, the photo-initiator is a free radical photo-initiator, a cationic photo-initiator, or any combination thereof. In one embodoment, the free radical photo-initiators are benzophenones, acylphosphine oxide, alpha-ammo ketone or any combination thereof. In one embodiment, the cationic photo-initiator is selected from the group comprising: aryldiazonium salt, dioryliodonium salts, triarylsulphonium salts, triarylselennonium salts and triarylsulfonium hexafluoroantinionate salts, or any combination thereof.
In one embodiment, the photo-initiator further comprises a co-initiator component. In another embodiment, the co-initiator component is triethanol amine.
In one embodiment, the stabilizer is 4-methoxy phenol.
Furthermore, in another embodiment, the present invention provides a method for the preparation of a three dimentional object by three-dimentional printing comprising the step of dispensing a model composition from a first dispenser, the model composition comprising at least one reactive component, at least one photo-initiator, at least one surface-active agent, and at least one stabilizer; dispensing a support composition from a second dispenser, the support composition comprising at least one Temperature Sensitive Polymer, at least one surface-active agent; and combining the model composition and the support composition in pre-determined proportions in produce a multiplicity of construction layers for forming the three-dimentional object, whereby the model composition is cured resulting in a solid form, and whereby the support composition is gelated by increasing temperature to above gelation temperature resulting in a gel form.
In one embodiment, the reactive component of the model composition is selected from the group consisting of an acrylic component, a molecule having one or more epoxy substituents, a molecule having one or more vinyl ether substituents, vinylpirolidone, vinylcaprolactam, or any combination thereof. In another embodiment, the reactive component of the model composition is comprised of at least one acrylic component. In another embodiment, the acrylic component is an acrylic monomer, an acrylic oligomer, an acrylic crosslinker, or any combination thereof. In another embodiment, the reactive component of the model composition further comprises a molecule having one or more epoxy sybstituents, a molecule having one or more vinyl ether substituents, vinylcaprolactam, vinylpyrolidone, or any combination thereof. In another embodimrnt, the reactive component of the model composition further comprises vinyl caprolactam. In another embodiment, the reactive component of the model composition is a molecule having one or more vinyl ether substituents. In another embodiment, the reactive component of the model composition is a molecule having one or more epoxy substituents.
In one embodiment, the photo-initiator of the model composition is a free radical photo-initiator, a cationic photo-initiator or any combination thereof.
In one embodiment, the model composition further comprises at least one pigment and at least one dispersant. In another embodiment, the pigment in a white pigment, an organic pigment, an inorganic pigment, a metal pigment in a combination thereof. In another embodiment, the model composition further comprises a dye.
Furthremore, in another embodiment, the present invention provides a three dimentional object, obtained by any of the methods of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will be understood and appreciated more fully from the following detailed description taken in conjunction with the appended drawings in which:
FIG. 1: AS typical RTG graph of viscosity temperature relation is shown. At a specific temperature T=T_minthe specific composition has its minimal viscosity Vmin. Raising the temperature causes the viscosity to increase until T=T_gelthe composition is transfored into gel i.e. an abrupt change in its mechanical properties. Raising the temperature further to T_T ₂will raise the viscosity until the required viscosity for supporting material is attained.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention erlate to novel polymeric compositions that exhibit Reverse Thermal Gelation (RTG) properties for use as Support Materials (SM) in the manufacturer of three-dimentional objects. These polymers are Temperature Sensitive Polymers that respond with a significant change of properties to a small change in temperature. Temperature Sensitive Polymers exhibit cloud point (CP) or lower critical solution temperature (LCST) in aqueous solution. Water-soluble Temperature Sensitive Polymers are chosen to give low viscosity liquid at low temperature when dissolved in water and by trhat to permit easy dispensing at low temperature. Raising the temperature above their gelation temperature (T_gel) will result in solidification of the compostion. At its gel position the material has favorable characteristics as a support and building material. The gel layers have the appropriate toughness and dimentional stability to support the model layers during the building process. After the building process is complete the gel can be cooled down to a temperature below its T_gelso the gel can liquefy and be removed easily by rinsing with water.
In one embodiment, the methods of present invention are used with systems and methods as described by th US application of Ser. No. 09/412,618. In another embodiment the methods of the present invention may be used with other systems and methods for building three-dimentional objects, for example, without limitation, for stereolithography, described above.
In one embodiment, the present invention provides a composition suitable for supporting and/or building a three-dimentional object, the composition comprising at least one Temperature Sensitive Polymer, and at least one surface active agent, wherein the composition exhibits Reverse Thermal Gelation (RTG) properties. In another embodiment, the present invention further provides a method for building a three-dimentional object by three dimentional printing, the method comprising the steps of disposing of building composition, comprising at least one Temperature Sensitive Polymer, wherein the building composition exhibits Reversal Thermal Gelation (RTG) properties and at least one surface-active agent; and gelating the building composition by increasing temperature to above gelation temperature, thereby constructing the three dimentional object in another embodiment, the present invention further provides a method for supporting a three-dimentional object during construction, the method comprising the step of contacting the object with a support composition, comprising at least one Temperature Sensitive Polymer, wherein the support composition exhibits Reverse Thermal Gelating (RTG) properties and at least one surfacce-active agent; gelating the support composition by increasing temperature to above gelation temperature, thereby supporting the three dimentional object. In another embodiment, the present invention further provides a method for preparation of a three-dimentoinal object by three-dimentional printing comprising the step of dispensing a model composition from a first dispenser, the model composition comprising at least one reactive component, at least one photo-initiator, at least one surface-active agent, and at least one stabilizer; disprnsing a support composition from a second dispenser, the support composition comprosing atleast one Temperature Sensitive Polymer, at least one surface-active agent; and combining the model composition and the support composition in pre-determined proportions to produce a multiplicity of construction layers for forming the three-dimentional object; whereby the model composition is cured resulting in a solid form, and whereby the support composition is gelated by increasing temperature to above gelation temperature resulting in a gel form.
Non-limiting examples of polymeric compositions used with embodiments of the present invention are based on water solutions of Temperature Sensitive Polymers, which exhibit RTG, for example:

- 1. ABA triblocks oligomers.
- 2. Multi blocks polymers of ABA, of random or repetitive configuration.
- 3. Star configuration molecules, often called radial.
- 4. Gatted chains, often called comb.

The RTG phenomenon con be used to benefit:

- 1. Easy dispensing at low temperature and low viscosity.
- 2. The use of the dispensed material as a support material (SM) in the Rapid Prototyping (RP), Rapid Manufacturing (RM), and Rapid Tooling (RT) processes: raising the material temperature above its gelation temperature will transform it into gel.
- 3. Easy cleaning of the SM and RM: the RTG phenomenone is reversible, i.e. at a temperature lower than its gelation temperature the material liquefies, thus the SM can easily be washed off.

The effect of temperature is interesting: an increase in the aggregation number with increasing temperature has been observed, while the minellar radius remains constant. The conclusions are complicated by the rather broad CMT transition, and the fact that dynamic light scattering detects the micelle hydrodynamic radius, which includes the water hydrating the BO segments.
PEO-PPO-PEO copolymer solutions of high copolymer concentration exhibit a dramatic change in viscosity at temperatures close to ambient, revealing Reverse Thermal Gelation (RTG) properties. Many studies have shown that the observe changes in viscosity are due to a “hard-sphere crystallization” as the micells concentration approaches the critical volume fraction of 0.53 (micells close-packed).
The RTG phenomenon is not constricted only to micellar polymeric systems. Another RTG property of the particular type of polymers—Ethyl(hydroxyethyl)cellulose (EHEC), was discovered same year ago by Andres Carlsson and his colleages. Solutions of EHEC and ionic surfactants of sertain compositions are converted to gels when the temperature is increased. Moreover, the anomalous behaviour of these EHEC-surfactant formulation fully reversible as liquid solutions form clear and stable gels and re-liquefy when cooled to temperatures below the gelation point. The transition can occur at temperatures as low as 30-40° C. and the concentration of polymer and ionic surfactant needed to bring about the thermal gelation is rather low-in total about 1 wt %. The enhancement od surfactant binding to the EHEC polymeric chains at increased temperatures has been proposed to play a major role for the gelation. At increasing temperature the surfactant aggregation numbers becomes lower and the degree of ionization of the clusters becomes higher. This is due to hydrophobic association of polymer hydrophobic parts with the clusters at higher temperature. Thus, as long as segments from more than one polymer chains are associated with the clusters, an increase in the number of clusters may lead to an increased cross-linking which could result in gel formation.
Another type of temperatures sensitive polymer is Poly(N-isopropylacrylamide) [Poly (NIPAM)]. This polymer when prepared using free-radical initiator is soluble in solvents, which are capable of forming reasonably strong hydrogen bonds. In aqueous solution, it shows a lower critical solution temperature (LCST) at about 31° C. Poly (NIPAM) gel in water undergoes a volume-phase transition from swollen gel to a shrunken gel at about 33.6° C. This is due to the hydrophobic interaction between the polymer and water molecule. The phase separation takes place by association of the polymer molecules into larger aggregates formed by intermolecular hydrogen bonding and nonpolar bonds. The tendency for the formation of such bonds is also enhanced by the destabilization of the like structure in water when nonpolar solutes aggregate. Alternatively, it is also possible to ascribe the phenomenon to the fact that the polymer is more ordered in dilute solution than in the concentrated phase and that this ordering is due to the relatively strong hydrogen bonds formed between water and the polymer. As the temperature is raised, these hydrogen bonds become weaker and the solution becomes unstable.
Embodiments of the present invention further relate to methods of using these compositions in Rapid Prototyping (RP), Rapid Manufacturing (RM) and Rapid Tooling (RT). Accordingly, it is one object of an embodiment of the present invention to provide novel temperature sensitive compositions in which can be used in the manufacturing of a three-dimentional object by three-dimentional printing.
It has now been discovered that these and other objectives can be achieved by the present invention, which provides polymeric compositions suitable for supporting and/or building a three-dimentional object.
In one embodiment the support and/or building composition is used as a support composition for supporting a three-dimentional object during construction. In another embodiment a model composition is used as a building composition for construction of a three-dimentional object.
In another embodiment the support and/or building composition is used as a building composition, for example, without limitation, in medical applications.
Support and/or Building Composition
In one embodiment, the present invention provides a composition suitable for supporting and/or building a three-dimentional objects, the composition comprising at least one Temperature Sensitive Polymer; and at least one surface-active agent, wherein the composition exhibits Reverse Thermal Gelation (RTG) properties.
Temperature Sensitive Polymers have been extensively studied over the last decade. Number of possible molecular mechanisms can cause sharp transistions in these polymeric systems. In most of these mechanisms water is involved.
The main mechanism of a thermally induced phase separation is the release of hydrophobically bound water. A locally higher order of water molecules exists around the hydrophobic unit of the polymer in solution. As gelation occurs the interaction between the hydrophobic units of polymer molecules, squeezes out these ordered water molecules into the bulk silution of lower order. This results in an overall disorder or increased entropy, which is the driving force for hydrophobic association.
One of the most famous groups in Temperature Sensitive Polymers is the Pluronic block copolymers. The Pluronics are a series of water-soluble block copolymers, composed of two polyoxyethylene blocks separated by a polyoxypropylene block. The Pluronics all have the general structure of PEO-PPO-PEO. The ability of Pluronic copolymers to form micells and gels makes them an important class od surfactant, which find widespread use in industrial applications such as detergency, dispersion stabilization, foaming, emulsification, lubrication and formation of cosmetics and inks. The amphiphilic property of Pluronic copolymers is the reason for their ability to create micells above the CMC (critical micellization concentration) and the CMT (critical micellization temperature). The micellizationof block copolymers, as in the case of conventional surfactants, obeys the closed association model, which assumes equilibrium between molecularly disposed copolymer (unimer) and multimolecular aggregates (micelles). In the case of pluronic, when micellization occurs the degree of structurring of the water molecules is decreased. The hydrogen bonding structure in the water is restored and the water entropy increases, overcoming the entropy loss due to the localization of the hydrophobic chains in the micelles. The structure of the pluronic micelles in water has been investigated in many studies. In general, the unimer size is found to be approximately 1 nm and the micelle size 10 nm, independent of copolymer concentration.
In one embodiment, the Temperature Sensitive Polymer is a water-soluble Temperature Sensitive Polymers. In another embodiment, the water-soluble Temperature Sensitive Polymer is an ABA triblock oligomer, wherein A and B are oligomers. In another embodiment, A is a hydrophilic oligomer and B is a hydrophobic oligomer. In another embodiment, A is a hydrophobic oligomer and B is a hydrophilic oligomer. In another embodiment, A and B comprise aliphatic polyether and/or polyester units. In another embodiment, A is poly(ethylene oxide) and B is poly(propylene oxide).
Examples of Temperature Sensitive Polymers used with embodiments of the present invention are:

- The water solution block copolymers of poly(ethylene ocide)-poly(propylene oxide)-poly(ethylene oxide) which are commercially awailable as Poloxamers (ICI company) and Pluronics (Basf company). The types of Pluronics block copolymers which create gels in aqueous solutions at ambient temperature are: F-127, F-108, F-98, F-88, F-68, F-87, F-77, P-105, P-85, P-75, P-65, P-104, P-94, P-84, L-64, L-63, L-121, L-122.

In another embodiment, the water-soluble Temperature Sensitive Polymer is a multi blocks polymer of (ABA-X)_m, organized at random or repetitive configuration, wherein wherein A and B are oligomers, m is an integer of 1-30, and X is a chain extender. In one embodiment, X is selected from the group consisting of di, tri and poly isocyanates, di, try and poly carboxylic acids, diecyl halides, triphosgene or any combination thereof. In another embodoment, A is a hydrophilic oligomer and B is a hydrophobic oligomer. In another embodiment, A is a hydrophobic oligomer and B is a hydrophilic oligomer. In another embodiment, the multi block polymer of ABA is a polyurethane, a polycarbonate, a polyester or any combination thereof.
Polymers synthesized by chain extention of the Pluronic molecule. These polymers has the general structure of poly[Pluronic-X]_mWhereom X is a chain extender in the reapiting unit and m is the degree of polymerizasion (Dp). Examples for chains extenders are: di, tri ad poly isocyanates, di, tri and poly carboxylic acids, di acyl halides like adipoyl chloride and adipoyl bromides, and triphosgene or any combination thereof.
In another embodiment, the Temperature Sensitive Polymer is a poly (N substituted (meth)acrylamide). In one embodiment, the poly (N-substituted (meth)acrylamide) is a poly (N-isopropyl (meth)acrylamide). In another embodiment, the Temperature Sensitive Polymer is a poly vinyl alcohol derivative, hydroxypropyl methylcellulose, ethyl hydroxyethyl cellulose (EHEC) or any combination thereof.
Poly (N-substituted acrylamides) like poly N-isopropylacrylamide (Poly NIPAAM) (Eastman Kodak or Aldrich). N-substituted AAm and Methacrylamide (MAAm) or related monomers, Poly vinyl alcohol derivatives, hydroxypropyl methylcellulose, ethyl hydroxyethyl cellulose (EHEC) (Akzo Nobel) combined with ionic surfactants like SDS.
Another component of the formationi is a surface-active agent. A surface-active agent is used to reduce the surface tension of the formation to the value required for jetting, wich is typically around 30 dyne/cm. In one embodiment, the surface-active agent for the present invention is silicon surface active agent additive, marketed by Byk Chemie under the trade name of Byl 345, fluoro-based surface-active agent or any combination thereof.
In one embodiment, the support and/or building composition further comprises at least one photo curable reactive component, at leaqst one photo initiator, and at least one stabilizer.
The reactive component is typically chosen to increase the strength of the temperature responsive gel upon curing. The reactive component given a hydrophilic cured resin with very weak mechanical properties. The reactive component polymerizes upon curing at the same time when the Temperature Sensitive Polymer creates a gel. Thus the combunation of reactive component with the Temperature Sensitive Polymer creates an increase in the strength of the gel due to synergistic effect between the Temperature Sensitive Polymer and the reactive cured component. After curing, cooling down the gel below the gelation temperature, results in liquefiyng the gel, thus it can easily be removed by rinsing with water. The reactive component is at least one of an acrylic component, a molecule having one or more vinyl ether substituent, or a water-soluble and/or reducible, that can be dissolved in the aqueous medium when formulated, and after curing it is capable of swelling upon exposure in wateror to an alkaline or acidic water solution.
In one embodiment, the curable reactive componennt is a (meth)acrylic component. In one embodiment, the (meth)acrylic component is a (meth)acrylic monomer, a (meth)acrylic oligomer, or a combination thereof. In another embodiment, the (meth)acrylic component is a polyethylene glycol mono or di (meth)acrylated, polyether triacrylate or any combination thereof. In another embodiment, the reactive component is a water mmiscible component that is, after irradiation curing, capable of dissolving or swelling upon exposure to water or to an alkaline or acidic water solution. In another embodiment, the water miscible component is an acryloyl morpholine, (meth)acrylated urethane oligomer derivative of polyethylene glycol, a partially (meth)acrylated polyol oligomer, an (meth)acrylated oligomer having hydrophilic substituents or any combination thereof. In another embodiment, the hydrophilic substituents are acidic substituents, amino substituents, hydroxy substituents or any combination thereof. In another embodiment, the (meth)acrylic component is beta-carboxyethyl acrylate. In one embodiment, the reactive component is a molecule having one or more vinyl ether substituents. In another embodiment, the vinyl ether substituent is hydroxy-butyl vinyl ether.
The acrylic component is typically an acrylic monomer or acrylic oligomer, and may be any one of the examples defined hereinabove. Non-limiting examples of acrylic components for use in the formulation used with embodiments of the present invention are polyethylene glycol monoacrylate, marked by Laporte under the trade name Bisomer PEA-6 and polyethylene glycol diacrylate, marked by Sartomer under the trade names: SR-610 and SR 344, Etoxylated TMPTA: SR 415, Polyether triacrylate: CN-435, and the like.
The reactive component of the formulation can also be a water miscible component that, after curing is capable of swelling or even dissociating upon exposure to water or to an alkaline or acidic water solution. Examples of water miscible components used with embodiments of the present invention are: Aoryloyl morpholine marked by UCB under the trade name of ACMO, an acrylated urethane oligomer derivative of polyethylene glycol-polyethylene glycol urethane diacrylate, a partially acrylated polyol oligomer, an acrylated oligomer having hydrophilic substituent, or any combination thereof.
The hydrophilic substituent are acidic substituent, amino substituent, hydroxy substituent, or any combination thereof. An example of an acrylated oligomer with hydrophilic substituent is beta-carboxyethyl acrylate, which contains cidic substituents. The reactive component can also be a molecule having one or more vinyl ether substituent, which may be any of the compounds as defined hereinabove. An example of vinyl ether for the support and/or building composition material is hydroxy-butyl vinyl ether, marked by BASF under the trade name of HBVE.
In one embodiment, the photo-initiator id a free radical photo-initiator, a cationic photo-initiator, or any combination thereof.
In one embodiment, the free radical photo-initiators are benzophenones, acylphosphine oxide, alpha-amino ketone or any combination thereof.
In one embodiment, the photo-initiator further comprises a co-initiator component. In another embodiment, the co initiator component is triethanol amino.
The free radical photo-initiator can be any compound that produces a free radical on exposure to radiation such as ultraviolet or visible radiation and thereby initiates a polymerization reaction. Non-limiting examples of some suitable photo-initiators include benzophenones (aromatic ketones) such as benzophenone, methyl benzophenone, Michlers ketone and xanthones; acylphosphine oxide type photo-initiators such as 2,4,6-trimethylbenzolydiphenyl phosphine oxide (TMPO), 2,4,6-trimethylbenzolethoxyphenyl phosphine oxide (TEPO), and bisacylphosphine oxides (BAPO's) benzoins and benzoin alkyl ethgers such as benzoin, benzoin methyl ether and benzoin isopropyl ether and the like. Non limiting examples of photo-initiators are alpha-amino ketone, marked by Ciba Specialties Chemical Inc. (Ciba) under the trade name of Igracure 907; and bisacylphosphine oxide (BAPO's), marked by Ciba under the trade name of I-819.
The free-radical photo-initiator can be used alone or in combination with a co-initiator. Co-initiators are used with initiators that need a seond molecule to produce a radical that is active in the UV-system.
In one embodiment, the cationic photo-initiator is selected from the group comprising: aryldiazonium salts, diaryliodonium salts, triarylsulphonium salts, triarylselenonium salts and triarylsolphonium hexafluoroantimonate salts, or any combination thereof.
Suitable cationic photo-initiator used with embodiments of the present invention include, for example, compounds which form aprotic acids or bronsted acids upon exposure to ultraviolet and/or visible light sufficient to initiate polymerization. The photo-initiator used may be a single compound, a mixture of two or more active compounds, or a combination of two or more different compounds, i.e., Co-initiators. Non-limiting examples of suitable cationic photo-initiators are aryldiazonium salts, diaryliodonium salts, triarylsulphonium salts, triarylselenonium salts and the like. In one embodiment, the cationic photo-initiator is a mixture of triarylsolphonium hexafluoroantimonate salts marketed by Union Carbide as UVI-6974.
Other components of the composition are inhibitors (thermal stabilizers). In one embodiment, the stabilizer is 4-methoxy phenol. Inhibitors are employed in the formulations to permit the use of the formulation at room temperature and elevated temperatures, without cansing thermal polymerization.

Non-limiting examples of characteristic components of the polymeric compositions are provided in Table 1 herein below. Examples of possible formulations of the support and/or building compositions are provided in Table 2 herein below.

TABLE 1


Examples of Characteristic Components of
the Support and/or Building Compositions

		Chemical		Sup-
#	Trade Name	Type	Function	plier

A	Pluronic:	PEO-PPO-PEO	Temperature	BASF
	F-127, F-108, F-98,	block	sensitive
	F-88, F-68, F-87,	copolymer	polymer
	F-77, P-105, P-85,
	P-75, P-65, P-104,
	P-94, P-84, L-64,
	L-63, L-121, L-122.
B	Poly[Pluronic-X]_m	Polyureth-	Temperature	Home
	Chain extension	anes, Poly-	sensitive	made
	products of	carconates,	polymer
	Plutonic with	polyesters
	X-chain extender.
C	NIPAAM	N-Isopropyl	Temperature	Aldrich
		Acryl Amide	sensitive
			polymer
D	EHEC	Ethyl Hydroxy	Temperature	Akzo
		ethyl cellu-	sensitive	Nobel
		lose	polymer
E	Water	Water	Aqueous
			media
F	SDS	Sodium	Surface ac-	Aldrich
		dodecyl	tive agent
		sulphonate
G	Bisomer PEA-6	Polyethylene	Photo-curable	Laport
		Glycol	reactive
		monoacrylate	monomer
			Water soluble
H	SR-344	Polyethylene	Photo-curable	Sartomer
		Glycol (400)	reactive
		diacrylate	monomer
			Water soluble
I	ACMO	Acryloyl	Photo-curable	UCB
		morpholine	reactive
			monomer
			Water soluble
J	HBVE	Hydroxy Butyl	Vinyl ether	BASF
		Vinyl Ether	monomer
K	Irgacure-2959	Alpha-Hydroxy	Free radical	CIBA
		ketone	photo-
		For waterborn	initiator
		formulations	Type I
L	Triethanol	Ternary Amine	Free radical	J. T.
	Amine		Coinitiator	Baker
			for type II
			photoini-
			tiator
M	Byk 345	Silicon Sur-	Surface	Byk
		face Additive	agent	Chemie
N	MEHQ	4-Methoxy	Inhibitor	Sigma
		phenol	(thermal
			stabilizers)

TABLE 2


Examples of Possible Formulations of the
Support and/or Building Compositions

Example

A

B

C

D

E

F

G

H

I

J

K

L

M

N

1

X

2

X

3

X

4

X

5

X

6

X

7

X

8

X

9

X

10

X

11

X

12

X

13

X

In one embodiment, the formulation of the support and/or building composition is presented in entry No. 2.

In one embodiment, the formulation of the support and/or building composition is presented in entry No. 1.

In one embodiment, the formulation of the support and/or building composition is presented in entry No. 6.

In one embodiment, the formulation of the support and/or building composition is presented in entry No. 5.

Model Composition

In one embodiment the model composition is used for the building a three-dimentional object.
The model composition is formulated to give, after curing, a solid material with mechanical properties that permit the building and handling of three-dimentional models. The model composition used with an embodiment of the present invention comprises:

- at least one reactive component;
- at lease one photo-initiator;
- at least one surface-active agent; and
- at least one stabilizer.

In one embodiment, the reactive component is an acrylic component, a molecule having one or more epoxy substituents, a molecule having one or more vinyl ether substituents, vinyl pyrolidone, vinylcaprolactan, or any combination thereof. The acrylic component is an acrylic monomer, an acrylic oligomer, an acrylic crosslinker, or any combination thereof.
An acrylic monomer is a monofunctional acrylated molecule which can be, for example, esters of acrylic acid and methacrylic acid. An example of an acrylic monomer used with an embodiment of the present invention is phenoxyethyl acrylate, marketed by Sartomer under the trade name SR-339. Another non-limiting example of an acrylic monomer is marketed by Sartomer under trade name SR-9003.
An acrylic oligomer is a polyfunctional acrylated molecule which can be for example polyesters of acrylic acid and methacrylic acid and a polyhydric alcohol, such as polyacrylates and polymethacrylates of trimethylolpropane, pentaerythritol, ethylene glycol, propylene glycol and the like. Non-limiting examples of acrylic oligomers are the classes of urethane acrylates and urethane methacrylates. Urethane-acrylates are manufactured from aliphatic or cycloaliphatic diisocyanates or polyisocyanates and hydroxyl-containing acrylic acid esters. A non-limiting example is a urethane-acrylate oligomer marketed by Cognis under the trade name Photomer-6010.
An acrylic crosslinker is a molecule which provides enhanced crosslinking. Examples of such resins are 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, 1,6-hexamethylene glycol diacrylate, neopentyl glycol dimethacrylate, trimethacrylate triethylene glycol triacrylate, triethyelene glycol trimethacrylate, and the like. A non-limiting example of an acrylic crosslinker used with one embodiment of the is trimethylol propane triacrylate, marketed by Sartomer ubder the trade name SR-351. Another non-limiting example of a crosslinker is UVM-45, marketed by CRODA.
The reactive component in the model composition can also be a molecule having one or more vinyl ether substituents. Conventional vinyl ether monomers and oligomers which have at least vinyl ether group are suitable. Non-limiting example of vinyl ether are ethyl vinyl ether, propyl vinyl ether, isobutyl vinyl ether, cyclohexyl vinyl ether, 2-ethylhexyl vinyl ether, butyl vinyl ether, ethyleneglocol monovinyl ether, diethyleneglycol divinyl ether, butane diol divinyl ether, hexane diol divinyl ether, cyclohexane dimethanol monovinyl ether and the like. In one embodiment, the vinyl ether is 1,4-cyclohexane dimethanol divinyl ether, marketed by ISP under the trade name CHVE.

The reactive component in the model composition can also be a molecule having one or more epoxy substituents. In one embodiment, the conventional epoxy monomers and oligomers have at least one oxirane moiety. Non-limiting examples of suitable epoxy containing molecules are displayed in Table 3 below:

TABLE 3


Examples of Epoxy-Containing Reactive Component

Trade Name	Type of Material	Supplier

ERL-4299 or	Bis-(3,4 cyclohexylmethyl)	Union Carbide
UVR-6128	adipate
UVR-6105 and	3,4-epoxy cyclohexylmethyl-3,4-	Union Carbide
UVR-6110	epoxycyclohexyl carboxylate
D.E.R. 732	Aliphatic epoxy, Polyglycol	Dow chemicals
	diglycidyl ether
Vinylcy-	1,2 epoxy-4-vinylcyclohexane	Union Carbide
clohexene
Monoxide
D.E.N. 431	Epoxy novolac resin	Dow corning
UVR-6216	1,2-epoxy hexadecane	Union Carbide
UVI-6100	Cycloaliphatic epoxide diluent	Union Carbide
Vikoflex 7170	Fullyl epoxidized soy bean oil	Elf Atochem,
		INC.
ERL-4221D	3,4-epoxy cyclohexylmethyl	Union Carbide
	3,4-epoxy cyclohexane
	carboxylate

The reactive component of the model composition can comprise any combination of an acrylic component as defined hereinabove, a molecule having one or more epoxy substituents as defined hereinabove, a molecule having one or more vinyl ether substituent as defined hereinabove, vinylcaprolactam and vinylpyrolidone.
In one embodiment, the reactive component of the model composition comprises an acrylic monomer, an acrylic oligomer, an acrylic crosslinker and vinylcaprollactam. In another embodiment, the reactive component comprises an acrylic component as defined hereinabove and a molecule having one or more epoxy substituents as defined hereinabove. In another embodiment, the reactive component of the model composition comprises an acrylic component as defined hereinabove and a molecule having one or more vinyl ether substituents as defined hereinabove. I another embodiment, the reactive component in the model composition comprises a molecule having one or more vinyl ether substituents as sefined hereinabove, an a molecule having one or more epoxy substituents as defined hereinabove.
The photo-initiator of the model composition and of the support and/or building composition may be the same or different, and is a free radical photo-initiator, a cationic photo-initiator, or any combination thereof.
The free radical photo-initiator can be any compound that produces a free radical on exposure to radiation such as ultraviolet or visible radiation and thereby initiates a polymerization reaction. Examples of some suitable photo-initiators include benzophenones (aromatic ketones) such as benzophenone, methyl benzophenone, Michler's ketone and xanthones; acylphosphine oxide type photo-initiators such as 2,4,6-trimethylbenzolydiphenyl phosphine oxide (TMPO), 2,4,6-trimethylbenzoylethoxyphenyl phosphine oxide (TEPO), and bisacylphosphine oxides (BAPO's); benzoins and bezoin alkyl ethers such as benzoin, benzoin methyl ether and benzoin isopropyl ether and the like. Non-limiting examples of photo-initiators are alpha-amino ketone, marketed by Ciba Specialties Chemicals Inc. (Ciba) under the trade name Irgacure 907, and bisacylphosphine oxide (BAPO's), marketed by Ciba under the trade name I-819.
The free-radical photo-initiator can be used alone or in combination with a co-initiator. Co-initiators are used with initiators that need a second molecule to produce a radical that is active in the UV-systems. Benzophenone is an example of a photoinitiator that requires a second molecule, such as an amine, to produce a reactive radical. After absorbing radiation, benzophenone reacts with a ternary amine by hydrogen abstraction, to generate an alpha-amino radical which initiates polymerization of acrylates. A non-limiting example of a class of co-initiators are alkonolamines such as triethylamine, methyldiethanolamine and triethanolamine.
Suitable cationic photo-initiators used with embodiments of the present invention include compounds, which form aprotic acids or Bronstead acids upon exposure to ultraviolet and/or visible light sufficient to initiate polymerization. The photo-initiator used may be a single compound, a mixture of two or more active compounds, or a combination of two or more different compounds, i.e., co-initiators. Non-limiting examples of suitable cationic photo-initiators are aryldiazonium salts, diaryliodonium salts, triarylsulphonium salts, triarylselenonium salts and the like. In one embodiment, the cationic photo-initiator for the present invention is a mixture of triarylsolfonium hexafluoroantimonate salts marketed by Union Carbide as UVI-6974.
Other embodiments of the model composition and the support and/or building composition used with embodiments of the present invention are surface-active agents and inhibitors (thermal stabilizers). A surface-active agent is used to reduce the surface tension of the formulation to the value required for jetting, which is typically around 30 dyne/cm. In one embodiment of the present invention, a surface-active agent is silicone surface additive, marketed by Byk Chemie under the trade name Byk 307. Inhibitors are employed in the formulations of the model composition and the support and/or building composition to permit the use of the formulation at high temperature, preferably around 85C, without causing thermal polymerization.
In one embodiment of the present invention, the model composition further comprises at least one pigment and at least one dispersant. The pigment is a white pigment, an organic pigment, an inorganic pigment, a metal pigment or a combination thereof. In another embodiment of the present invention, a white pigment is organic treated titanium dioxide, marketed by Kemira Pigments under the trade name UV TITAN M160 VEG. A non-limiting example of an organic pigment marketed by Elementis Specialities under the trade name Tint Aid PC 9703. Non-limiting examples of dispersants used with embodiments of the present invention are dispersants comprising a copolymer with acidic groups marketed by Byk Chemie under the trade name Disperbyk 110, and a dispersant comprising a high molecular weight block copolymer with pigment affinic groups, marketed by Byc Chemie under the trade name Disperbyk 163.
Furthermore, in one embodiment of the present invention, combinations of white pigments and dyes are used to prepare colored resins. In such combinations, the white pigment has a double task: 1) to impart opacity; and 2) to shield the dye from UV radiation, to prevent bleaching of the resin. Thus, in accordance with one embodiment of the present invention, the model composition further comprises a dye. The dye is chosen so as not to interfere with the curing efficiency of the formulation of the model composition. the dye may be any of a broad class of solvent soluble dyes. Some non-limiting examples are azo dyes, which are yellow, orange, brown and red; anthraquinone and triarylmethane dyes which are green and blue; and azine dye which is black. In one embodiment of the present invention, the dye is Solvent Red 127, marketed by Spectra Colors Corp. under the trade name Spectrasol RED BLG.
The relative proportions of the different component of the model composition can vary. In one embodiment, the model composition comprises the following components: 50% acrylic oligomer(s), 30% acrylic monomer(s), 15% acrylic crosslinker, 2% photoinitiator, surface active agent, pigments, dispersants; and stabilizers.

Non-limiting examples of formulations of the model composition are provided hereinbelow in Tables 4-6, to which reference is now made. Tables 4 and 5 illustrate examples of possible formulations of the model composition. Table 6 illustrates examples of colored formulations, which comprise pigments, dispersants and dyes, as defined herinabove. To any of the examples in Tables 4 and 5 may be added the combination of the colorants of Table 6.

TABLE 4


Examples of Characteristic Formulation
Components of Model Composition

			Function in the
#	Trade Name	Chemical Type	formulation	Supplier

A	Photomer-	Urethane Acrylate	Oligomer	Cognis
	6010	Oligomer
B	SR-339	Phenoxy ethyl	monomer	Sartomer
		Acrylate
C	SR-351	Trimethylol	Cross-linker	Sartomer
		propane triacrylate
D	Irgacure	alpha-Amino Ketone	Free radical	Ciba
	907		photo-initiator	Specialties
				Chemical
				Inc.
E	BP	Benzophenone	Free radical	Satomer
			photo-initiator
F	Triethanol	1. Ternary Amine	Free radical	Sigma
	Amine		Coinitiator
G	Byk 307	Silicone Surface	Surface agent	Byk
		Additive		Chemie
H	MEHQ	4-Methoxy phenol	Inhibitor	Sigma
I	Cyracure	3,4 Epoxycyclo-	Epoxy	Union
	UVR-6110	hexylmethyl-3,4-	oligomer	Carbide
		epoxycyclohexyl-
		carboxylate
J	UVI-6974	Mixed Triarylsul-	Cationic	Union
		fonium Hexafluoro-	photo-initiator	Carbide
		antimonate Salts
K	CHVE	1,4-cyclohexane	Vinyl Ether	ISP
		dimethanol	Monomer
		divinyl ether
L	UV TITAN	Organic Treated	White pigment	KEMIRA
	M160 VEG	Titanium Dioxide		PIGMENTS
M	Disperbyk	Copolimer with	Pigment	Byk
	110	acidic groups	Dispersant	Chemie
N	Spectrasol	Solvent Red 127	Dye	Spectra
	RED BLG			Colors
				Corp.
O	Tint Aid	Organic pigment	Organic	Elementis
	PC 9703		pigment	Specialties
P	Disperbyk	High molecular	Pigment	Byk
	163	weight block	Dispersant	Chemie
		copolymer with
		pigment affinic
		groups
Q	V-Cap	Vinylcaprolactam	Monomer	ISP
R	V-Pyrol	Vinylpyrolidone	Monomer	ISP

TABLE 5


Examples of Possible Formulation
Compositions of Model Composition

Example

A

B

C

D

E

F

G

H

I

J

K

Q

R

1

X

2

X

3

X

4

X

5

X

6

X

7

X

8

X

9

X

10

X

11

X

12

X

13

X

14

X

15

X

TABLE 6


Examples of Colored Formulations of Model Composition

Example

	L	M	N	O	P

16	X	X
17	X	X	X
18	X	X		X	X
19				X	X
20			X	X	X

In one embodiment, the formulation of the model composition is presented in entry No. 14 of Table No. 5. According to this embodiment, the model composition comprises

- an acrylic oligomer, which can be any acrylic oligomer as defined hereinabove, and which is according to one embodiment a urethane acrylate oligomer;
- an acrylic monomer, which can be any acrylic monomer as defined hereinabove, and which is according to one embodiment a phenoxy ethyl acrylate;
- an acrylic crosslinker, which can be any acrylic crosslinker as defined hereinabove, and which is according to one embodiment a trimethylol propane triacrylate;
- a radical photo-initiator, which can be any radical photo-initiator as defined hereinabove, and which is according to one embodiment an alpha-amino keyone;
- a surface agent, which is according to one embodiment a silicon surface additive;
- an inhibitor, which is according to one embodiment a 4-methoxyphenol; and
- vinylcarpolactam.

Reference is made to FIG. 1: a typical RTG graph of viscosity—temperature relation is shown. At a specific temperature T=T_minthe specific composition has its minimal viscosity η_min. Raising the temperature induces an increase in viscosity until at T=T_gelthe composition is transformed into gel, i.e. an abrupt change in the mechanical properties of the composition occurs. Further raising the temperature to T=T₂increases the viscosity of the gel until the required viscosity for the supporting and/or building composition is attained. Moreover, the gelation process is reversible, i.e. lowering the temperature of the below T=T_gel,for example T=T₁, causes the gel to liquefy to its starting liquid phase.
Further, the polymeric composition has a first low viscosity, η₁, at a first temperature, T₁that is lower than T_gel. η₁is compatibel with ink-jet printer at T₁. After being dispensed, the composition temperature is typically raised to a temperature above T_gelwhereas the material becomes a stiff gel. At its gel position the material typically has favorable characteristics as asupport and/or building material. The gel layers typically have the appropriate toughness and dimensional stability. Furthermore, after the construction process is completed, the gel can easily be washed awy by lowering the temperature below the gelling temperature (T_gel) at which temperature the gel typically liquefies, followed by rinsing with water. The composition is typically totally water-soluble even at its gel position. In addition, the composition typically has no toxic effect on environment and can be disposed without causing any ecological harmful effects.
Embodiments of the present invention relate to using phenomenon of Reverse Thermal Gelation (RTG) and the materials exhibiting these characteristics as support materials (SM) in the RP, RT or RM processes. Several basic compositions exhibiting the RTG phenomenon are disclosed; other may be used with embodiments of the present invention.
“Reverse Thermal Gelation” (RTG) is the phenomena whereby a material or a solutioin of a material spontaneously increases in viscosity, and in many instances transforms into a semisolid gel, as the temperature of the solution is increased above the gelation temperature of the copolymer. When cooled below the gelation temperature, the gel spontaneously reverses to reform the lower viscosity solution. This cycling between the solution and the gel may be repeated because the sol/gel transition does not involve any change in the chemical composition of the polymer system. All interactions to create the gel are physical in nature and do not involve the formation of breaking of covalent bonds. “Gelation temperature” means a water based solution having a gel forming block copolymer dissolved therein at a functional concentration, and maintained at a temperature above or below the gelation temperature such that gel formation does not occur.
In the above description, various aspects of the present invention have been described. For purposes of explanation, specific configurations and details were set forth in order to provide a through understanding of the embodiments of the present invention. However, it will also be apparent to one skilled in the art that the embodiments of the present invention may be practiced without the specific details presented herein. Furthermore, well-known features may be omitted or simplified in order not to obscure the embodiments of the present invention.
It will be appriciated by persons skilled in the art that the embodiments of the present invention is not limited by what has been particularly shown and described hereinabove, and that numerous modifications, all of which fall within the scope of the embodiments of the present invention, exist. Rather the scope of the invention is defined by the claim that follows:

Claims

1. A composition suitable for supporting and/or building a three-dimentional object, said composition comprising:

at least one Temperature Sensitive Polymer; and

at least one surface-active agent,

wherein said composition exhibits Reverse Thermal Gelation (RTG) properties.

2. The composition according to claim 1, wherein said Temperature Sensitive Polymer is a water-soluble Temperature Sensitive Polymer.

3. The composition according to claim 2, wherein said water-soluble Temperature Sensitive Polymer is an ABA triblock oligomer, wherein A and B are oligomers.

4. The composition according to claim 3, wherein A is a hydrophilic oligomer and B is a hydrophobic oligomer.

5. The composition according to claim 3, wherein A is a hydrophobic oligomer and B is a hydrophilic oligomer.

6. The composition according to claim 3, wherein A and B comprise aliphatic polyether and/or polyester units.

7. The composition according to claim 3, wherein A is poly(ethylene oxide) and B is poly(propylene oxide).

8. The composition according to claim 2, wherein said water-soluble Temperature Sensitive Polymer is a multi blocks polymer of (ABA-X)_m, organized at random or repetitive configuration, wherein A and B are oligomers, m is an integer of 1-30, and X is a chain extender.

9. The composition according to claim 8, wherein said X is selected from the group consisting of di, tri and poly carboxylic acids, diacyl halides, triphosgene or any combination thereof.

10. The composition according to claim 8, wherein A is a hydrophilic oligomer and B is a hydrophobic oligomer.

11. The composition according to claim 8, wherein A ia a hydrophobic oligomer and B is a hydrophilic oligomer.

12. The composition according to claim 8, wherein said multi block polymer of ABA is a polyurethane, a polycarbonate, a polyester or any combination thereof.

13. The composition according to claim 2, wherein said Temperature Sensitive Polymer is a poly(N-substituted (meth)acrylamide).

14. The composition according to claim 13, wherein said poly(N-substituted (meth)acrylamide) is a poly (N-isopropyl (meth)acrylamides).

15. The composition according to claim 2, wherein said Temperature Sensitive Polymer is a poly vinyl alcohol derivetive, hydroxypropyl methylcellulose, ethyl hydroxyethyl cellulose (EHEC) or any combination thereof.

16. The composition according to claim 1, wherein said surface-active agent is capable of resucing the surface tension of said composition to about 30 dyne/cm.

17. The composition according to claim 1, wherein said surface-active agent is a silicon surface-active agent additive, a fluoro-based surface-active agent or a combination thereof.

18. The composition according to claim 1, wherein said composition further comprises:

at least one photo curable reactive component;

at least one photo-initiator; and

at least one stabilizer.

19. The composition according to claim 18, wherein said photo curable reactive compound is a (meth)acrylic component.

20. The composition according to claim 19, wherein said (meth)acrylic component is a (meth)acrylic monomer, a (meth)acrylic oligomer, or a combination thereof.

21. The composition according to claim 19, wherein said (meth)acrylic component is a polyetheline glycol mono or di (meth)acrylated, polyether triacrylate or any combination thereof.

22. The composition according to claim 18, wherein said reactive component is a water miscible component that is, after irradiation or curing, capable of dissolving or swelling upon exposure to water or to an alkaline or acidic water solution.

23. The composition according to claim 22, wherein said water miscible component is an acryloyl morpholine, a (meth)acrylated urethane oligomer derivative of polyethylene glycol, a partially (meth)acrylated polyol oligomer, an (meth)acrylated oligomer having hydrophilic substituents or any combination thereof.

24. The composition according to claim 23, wherein said hydrophilic substituent is an acidic substuent, an amino substituent, a hydroxy substituent, or any combiination thereof.

25. The composition according to claim 19, wherein said (meth)acrylic component is beta-carboxyethyl acrylate.

26. The composition according to claim 19, wherein said reactive component is a molecule having one or more vinyl ether substituents.

27. The composition according to claim 26, wherein said vinyl ether substituent is hydroxy-butyl vinyl ether.

28. The composition according to claim 18, wherein said photo-initiator is a free radical photo-initiator, a cationic photo-initiator, or any combination thereof.

29. The composition according to claim 28, wherein said free radical photo-initiator is benzophenone, an acylphosphine oxide, an alpha-amino ketone or any combination thereof.

30. The composition according to claim 28, wherein said cationic photo-initiator is selected from the group consisting of aryldiazonium salts, diaryliodonium salts, triarylsulphonium salts, triarylselenonium salts and triarylsolphonium hexafluoroantimonate salts.

31. The composition according to claim 28, wherein said photo-initiator further comprises a co-initiator component.

32. The composition according to claim 31, wherein said co-initiator component is triethanol amine.

33. The composition according to claim 18, wherein said co-initiator component is triethanol amine.

34. A method for building a three-dimentional object by three dimentional printing, said method comprising the steps of:

dispensing a building composition comprising:

at least one Temperature Sensitive Polymer; wherein said composition exhibits Reverse Thermal Gelation (RTG) properties; and

at least one surface-active agent; and

gelating said building composition by increasing temperature to above the gelation temperature of said composition, thereby constructing said three dimentional object.

35. The method according to claim 34, wherein said Temperature Sensitive Polymer is a water-slouble Temperature Sensitive Polymer.

36. The method according to claim 35, wherein said water-soluble Temperature Sensitive Polymer is an ABA triblock oligomer, wherein A and B are oligomers.

37. The method according to claim 36, wherein A is a hydrophilic oligomer and B ia hydrophobic oligomer.

38. The method according to claim 36, wherein A is a hydrophobic oligomer and B is a hydrophilic oligomer.

39. The method according to claim 36, wherein A and B comprise aliphatic polyether and/or polyester units.

40. The method according to claim 36, wherein A is poly(ethylene oxide) and B is poly(propylene oxide).

41. The method according to claim 35, wherein said water-soluble Temperature Sensitive Polymer is a multi block polymer of (ABA-X)_m, organized at random or repetitive configuration, wherein wherein A and B arer oligomers, m is an integer of 1-30, and X is a chain extender.

42. The method according to claim 41, wherein said X is selected from group consisting of di, tri and poly isocyanates, di, tri and poly carboxylic acids, diacyl halides, triphosgene or any combination thereof.

43. The method according to claim 41, wherein A is a hydrophilic oligomer and B is a hydrophobic oligomer.

44. The method according to claim 41, wherein A is a hydrophobic oligomer and B is a hydrophilic oligomer.

45. The method according to claim 41, wherein said multiblock polymer of ABA is a polyurethane, polycarbonate, polyester or any combination thereof.

46. The method according to claim 35, wherein said Temperature Sensitive Polymers are poly (N-substituted (meth)acrylamides).

47. The method according to claim 46, wherein said poly (N-substituted (meth)acrylamide is poly (N-isopropyl (meth)acrylamides).

48. The method according to claim 35, wherein said Temperature Sensitive Polymer is a poly vinyl alcohol derivative, hydroxypropyl methylcellulos, Ethyl hydroxyethyl cellulose (EHEC) or any combination thereof.

49. The method according to claim 34, wherein said surface-active agent is capable of reducing the surface tension of said composition to about 30 dyne/cm.

50. The method according to claim 34, wherein said surfacce-active agent is a silicon surface-active agent additive, a fluoro-based surface-active agent or a combination thereof.

51. The method according to claim 34, wherein said composition further comprises:

at least one photo curable reactive component;

at least one photo-initiator; and

at least one stabilizer,

wherein said method further comprises the step of curing said building composition, thereby increases the strength of said building composition.

52. The method according to claim 51, wherein said photo curable reactive component is a (meth)acrylic component.

53. The method according to claim 52, wherein said (meth)acrylic component is a (meth)acrylic monomer, a (meth)acrylic oligomer, or a combination thereof.

54. The method according to claim 52, wherein said (meth)acrylic component is a polyethylene glycol mono or di (meth)acrylated, polyether triacrylate or any combination thereof.

55. The method according to claim 51, wherein said reactive component is a water miscible component that is, after irradiation or curing, capable of dissolving or swelling upon exposure to water or to an alkaline or acidic water solution.

56. The method according to claim 55, wherein said water miscible component is an acryloyl morpholine, a (meth)acrylated urethane oligomer derivative of polyethylene glycol, a partially (meth)acrylated polyol oligomer, an (meth)acrylated oligomer having hydrophilic substituents, or any combinatioin thereof.

57. The method according to claim 56, wherein said hydrophilic substituents is an acidic substituent, an amino substituent, a hydroxy substituent or any combination thereof.

58. The method according to claim 52, wherein said (meth)acrylic component is beta-carboxyethyl acrylate.

59. The method according to claim 52, wherein said reactive component is a molecule having one or more vunyl ether substituents.

60. The method according to claim 59, wherein said vinyl ether substituent is hydroxy-butyl vinyl ether.

61. The method according to claim 51, wherein said photo-initiator is a free radical photo-initiator, a cationic photo-initiator, or any combination thereof.

62. The method according to claim 61, wherein said free radical photo-initiator is benzophenone, an acylphosphine oxide, an alpha-amino ketone or any combination thereof.

63. The method according to claim 61, wherein said cationic photo-initiator is selected from the group consisting of aryldiazonium salts, diaryliodonium salts, triarylsulphonium salts, triarylselenonium salts, triarylsolphonium hexafluoroantimonate salts.

64. The method according to claim 61, wherein said photo-initiator further comprises a co-initiator component.

65. The method according to claim 64, wherein said co-initiator component is triethanol amine.

66. The method according to claim 51, wherein said stabilizer is 4-methoxy phenol.

67. A method for supporting a three-dimentional object during construction, said method comprising the step of:

contacting said object with a support composition, said support composition comprising:

at least one Temperature Sensitive Polymer, wherein said support composition exhibits Reverse Thermal Gelation (RTG) properties; and

at least one surface-active agent; and

gelating said support composition by increasing temperature to above the gelation temperature of said composition, thereby supporting said three dimentional object.

68. The method according to claim 67, further comprising the step of removing said support composition after construction of said object by cooling said support composition to a temperature below the gelation temperature of said compositioni.

69. The method according to claim 67, wherein said construction comprises Rapid Prototyping (RP), Rapid Manufacturing (RM) or Rapid Tooling (RT).

70. The method according to claim 67, wherein said construction comprises rapid tooling (RT), wherein said rapid tooling (RT) comprises

building a casting mold with said support composition for holding said object; and

building said object in said mold.

71. The method according to claim 70, further comprising the step of removing said mold by cooling said support composition to a temperature below the gelation temperature of said composition.

72. The method according to claim 67, wherein said construction comprises Rapid Manufacturing (RM), wherein said rapid manufacturing (RM) comprises direct manufacturing of finished parts.

73. The method according to claim 67, wherein said Temperature Sensitive Polymer is a water-soluble Temperature Sensitive Polymer.

74. The method according to claim 73, wherein said water-soluble Temperature Sensitive Polymer is an ABA triblock oligomer, wherein A and B are oligomers.

75. The method according to claim 74, wherein A is a hydrophilic oligomer and B is a hydrophobic oligomer.

76. The method according to claim 74, wherein A is a hydrophobic oligomer and B is a hydrophilic oligomer.

77. The method according to claim 74, wherein A and B comprise aliphatic polyether and/or polyester units.

78. The method according to claim 74, wherein A is poly(ethylene oxide) and B is poly(propylene oxide).

79. The method according to claim 73, wherein said water-soluble Temperature sensitive Polymer is a multi block polymer of (ABA-X)_m, organized at random or repetitive configuration, wherein A and B are oligomers, m is an integer of 1-30, and X is chain extender.

80. The method according to claim 79, wherein said X is selected from the group consisiting of di, tri and poly isocyanates, di, tri and poly carboxylic acids, diacyl halides, triphosgene or any combination thereof.

81. The method according to claim 79, wherein A is a hydrophilic oligomer and B is a hydrophobic oligomer.

82. The method according to claim 79, wherein A is a hydrophobic oligomer and B is a hydrophilic oligomer.

83. The method according to claim 79, wherein said multi block plymer of ABA is a polyurethane, polycarbonate, polyester or any combination thereof.

84. The method according to claim 73, wherein said Temperature Sensitive Polymers are poly (N-substituted (meth)acrylamides).

85. The method according to claim 79, wherein said poly (N-substituted (meth)acrylamides) is poly (N-isopropyl (meth)acrylamides).

86. The method according to claim 73, wherein said Temperature Sensitive Polymer is a poly vinyl alcohol derivative, hydroxypropyl methylcellulose, Ethyl hydroxyethyl cellulose (EHEC) or any combination thereof.

87. The method according to claim 67, wherein said surface-active agent is capable of reducing the surface tension of said composition to about 30 dyne/cm.

88. The method according to claim 67, wherein said surface-active agent is silicon surface-active agent additive, a fluoro-base surface-active agent additive, or a combination thereof.

89. The method according to claim 67, wherein said composition further comprises:

at least one photo-curable reactive component;

at least one photo-initiator; and

at least stabilizer;

whereby said method further comprises the step of curing said support composition, thereby increases the strength of said support composition.

90. The method according to claim 89, wherein said photo curable reactive component is a (meth)acrylic component.

91. The method according to claim 89, wherein said (meth)acrylic component is a (meth)acrylic monomer, a (meth)acrylic oligomer, or a combination thereof.

92. The method according to claim 90, wherein said (meth)acrylic component is a polyethylene glycol mono or di (meth)acrylated, polyether triacryalate or any combination thereof.

93. The method according to claim 89, wherein said reactive component is a water miscible component that is, after irradiation or curing, capable of dissolving or swelling upon exposure to water or to an alkaline or acidic water solution.

94. The method according to claim 93, wherein said water miscible component is an acryloyl morpholine, a (meth)acrylated urethane oligomer derivative of polyethylene glycol, a partially (meth)acrylated polyol oligomer, an (meth)acrylated oligomer having hydrophilic substituents, or any combination thereof.

95. The method according to claim 94, wherein said hydrophilic substituent is an acidic substituent, amino substituent, hydroxy substituent or any combination thereof.

96. The method according to claim 90, wherein said (meth)acrylic component is beta-carboxyethyl acrylate.

97. The method according to claim 89, wherein said reactive component is a molecule having one or more vinyl ether substituents.

98. The method according to claim 97, wherein said vinyl ether substituent is hydroxy-butyl vinyl ether.

99. The method according to claim 89, wherein said photo-initiator is a free radical photo-initiator, a cationic photo-initiator, or any combination thereof.

100. The method according to claim 99, wherein said free radical photo-initiator is a benzophenone, an acylphosphine oxide, and alpha-amino ketone or any combination thereof.

101. The method according to claim 99, wherein said cationic photo-initiator is selected from the group consisting of aryldiazonium salts, diaryliodonium salts, triarylsulphonium salts, triarylselnonium salts, triarylsolfonium hexafluoroantimonate salts.

102. The method according to claim 99, wherein said photo-initiator further comprises a co-initiator component.

103. The method according to claim 102 wherein said co-initiator component is triethanol amine.

104. The method according to claim 89, wherein said stabilizer is 4-methoxy phenol.

105. A method for the preparation of a three-dimentional object by three-dimentional printing the step of:

dispensing a model composition from a first dispenser, said model composition comprising:

at least one reactive component;

at least one photo-initiator;

at least one surface-active agent; and

at least one stabilizer;

dispensing a support composition from a second dispenser, said support composition comprising:

at least one Temperature Sensitive Polymer;

at least one surface-active agent; and

combining said model composition and said support composition in pre-determined proportions to produce a multiplicity of construction layers for forming said three-dimentional object;

whereby said model composition is cured resulting in a solid form, and

whereby said support composition is gelated by increasing temperature to above the gelation temperatrure of said composition, thereby resulting in a gel form.

106. The method according to claim 105, wherein said preparation od a three-dimentional object further comprising the step of removing said support composition after construction of said object by cooling said support composition to a temperature below the gelation temperature of said composition.

107. The method according to claim 105, wherein said reactive component of said model composition is selected from the group consisting of an acrylic component, a molecule having one or more epoxy substituents, a molecule having one or more vonyl ether substituents, vinylpyrolidone, vinylcarpolactam, or any combination thereof.

108. The method according to claim 105, wherein said reactive component of said model composition is comprised of at least one acrylic component.

109. The method according to claim 108, wherein said acrylic component is an acrylic monomer, acrylic oligomer, an acrylic crooslinker, or any combination thereof.

110. The method according to claim 108, wherein said reactive component of said model composition further comprises a molecule having one or more epoxy substituents, a molecule having one or more vinyl ether substituents, vinylcaprolactam, vinylpyrolidone, or any combination thereof.

111. The method according to claim 108, wherein said reactive component of said model composition further comprises vinylcaprolactam.

112. The method according to claim 108, wherein said reactive component of said model composition is a molecule having one or more vinyl ether substituents.

113. The method according to claim 105, wherein said reactive component of said model composition is a molecule having one or more epoxy substituents.

114. The method according to claim 105, wherein said photo-initiator of said model composition is a molecule having one or more epoxy substituents.

115. The method according to claim 105, wherein said model composition further comprises at least one pigment and at least one dispersant.

116. The method according to claim 105, wherein said pigment is a white pigment, an organic pigment, an inorganic pigment, a metal pigment or a combination thereof.

117. The method according to claim 105, wherein said model composition further comprises a dye.

118. The method according to claim 105, wherein said Temperature Sensitive Polymer is a water-soluble Temperature Sensitive Polymer.

119. The method according to claim 118, wherein said water-soluble Temperature Sensitive is an ABA triblocks oligomer, wherein A and B are oligomers.

120. The method according to claim 119, wherein A is a hydrophilic oligomer and B is a hydrophobic oligomer.

121. The method according to claim 119, wherein A is a hydrophobic oligomer and B is a hydrophilic oligomer.

122. The method according to claim 119, wherein A and B comprise aliphatic polyether and/or polyester units.

123. The method according to claim 119, wherein A is poly(ethylene oxide) and B is poly(propylene oxide).

124. The method according to claim 118, wherein said water-soluble Temperature Sensitive Polymer is a multi block polymer of (ABA-X)_m, organized at random or repetitive configuration, wherein A and B are oligomers, m is an integer of 1-30, and X is a chain extender.

125. The method according to claim 124, wherein said X is selected from the group consisting of di, tri and poly isocyanates, di, tri and poly carboxylic acids, duacil halides, triphosgene, or any combination thereof.

126. The method according to claim 124, wherein A is a hydrophilic oligomer and B is a hydrophobic oligomer.

127. The method according to claim 124, wherein A is a hydrophobic oligomer and B is a hydrophilic oligomer.

128. The method according to claim 124, wherein said multi block polymer of ABA is a polyurethane, polycarbonate, polyester or anycombination thereof.

129. The method according to claim 118, wherein said Temperature Sensitive Polymers are poly (N-substituted (meth)acrylamides).

130. The method according to claim 129, wherein said poly (N-substituted (meth)acrylamides) is poly (n-isopropyl (meth)acrylomides).

131. The method according to claim 118, wherein said Temperature Sensitive Polymer is a poly vinyl alcohol derivative, hydroxypropyl methylcellulose, Ethyl hydroxyethyl cellulose (EHEC) or any combination thereof.

132. The method according to claim 105, wherein said surface-active agent is capable of reducing the surface tension of said composition to about 30 dyne/cm.

133. The method according to claim 105, wherein said surface-active agent is a silicon surface-active agent additive, a fluoro-based surface-active agent additive, or a combination thereof.

134. The method according to claim 105, wherein said Support composition further comprises:

at least one photo curable reactive component;

at least one photo-initiator; and

at least one stabilizer;

whereby said method further comprises the step of curing said support composition, thereby increases the strength of said composition.

135. The method according to claim 134, whereinsaid photo curable reactive component is a (meth)acrylic component.

136. The method according to claim 135, wherein said (meth)acrylic component is a (meth)acrylic monomer, (meth)acrylic oligomer, or a combination thereof.

137. The method according to claim 134, wherein said (meth)acrylic component is a polyethylene glycol mono or di (meth)acrylated, polyether triacrylate or any combinatioin thereof.

138. The method according to claim 134, wherein said reactive component is a water miscible component that is, after irradiation or curing, capable of dissolving or swelling upon exposure to water or to an alkaline or acidic water solution.

139. The method according to claim 138, wherein said water miscible component is an acryloyl morpholine, a (meth)acrylated urethane oligomer derivative of polyethhylene glycol, a partially a (meth)acrylated polyol oligomer, an (meth)acrylated oligomer having hydrophilic substituents, or any combination thereof.

140. The method according to claim 139, wherein said hydrophilic substituent is an acidic substituent, amino substituent, hydroxy substituent or any combination thereof.

141. The method according to claim 135, wherein said (meth)acrylic component is beta-carboxyethyl acrylate.

142. The method according to claim 135, wherein said reactive component is a molecule having one or more vinyl ether substituents.

143. The method according to claim 142, wherein said vinyl ether substituent is hydroxy-butyl vinyl ether.

144. The method according to claim 134, wherein said photo-initiator is a free radical photo-initiator, a cationic initiator, or any combination thereof.

145. The method according to claim 144, wherein said free radical photo-initiator os abenzophenone, an acylphosphine oxide, an alpha-amino ketone or any combination thereof.

146. The method according to claim 144, wherein said cationic pjoto-initiator is selected from the group consisting of aryldiazonium salts, diaryliodomium salts, triarylsulphomium salts, triarylselanonium salts, triarylsolfonium hexafluoroantimonate salts.

147. The method according to claim 144, wherein said photo-initiator further comprises a co-initiator component.

148. The method according to claim 147, wherein said co-initiator component is triethanol amine.

149. The method according to claim 105, wherein said stabilizer is 4-methoxy phenol

150. The method according to claim 134, wherein said stabilizer is 4-methoxy phenol.

151. The method according to claim 105, further comprising the step of forming a multiplicity of supoprt layers for supporting sid object.

152. A 3-dimentional object is prepared by the method according to claim 34.

153. A 3-dimentional object is prepared by a method according to claim 67.

154. A 3-dimentional object is prepared by a method according to claim 105.