Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Compositions to be polymerized by wave energy wherein said...
Reexamination Certificate
2001-08-08
2003-07-01
Seidleck, James J. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Compositions to be polymerized by wave energy wherein said...
C522S104000, C522S090000, C522S096000, C522S093000, C522S153000, C522S154000, C522S152000, C522S151000, C430S269000, C430S270100, C430S280100, C430S281100, C430S284100, C430S285100, C428S482000, C525S010000, C525S921000, C525S934000
Reexamination Certificate
active
06586494
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a radiation-curable inkjet composition, and more particularly, to a radiation-curable inkjet composition for forming 3-D models or images and to a method for forming 3-D models or images using such radiation-curable inkjet compositions. The radiation-curable inkjet composition of the present invention comprises a semi-crystalline or crystalline, low-shrinkage, radiation-curable oligomeric material, a photoinitiator and a diluent. The composition will typically have a viscosity of between about 10 to about 50 centipoise at at least one temperature between about 50 to 140° C. in order to be jettable from the printer head of the inkjet printer.
Various methods are currently used for forming three-dimensional objects rapidly and automatically from three-dimensional computer data representing the objects. These methods are collectively referred to as rapid prototyping and manufacturing systems (RP & M). Rapid prototyping and manufacturing systems can generally be divided into three categories of manufacturing systems, namely, stereolithography, laminated object manufacturing, and selective deposition modeling.
In general, three-dimensional objects formed by rapid prototyping and manufacturing systems typically involve the formation of three-dimensional objects from computer data corresponding to the object by building up and adhering cross-sectional layers of the three-dimensional object. Alternatively, three-dimensional object production by rapid prototype and manufacturing systems is not limited to layer-by-layer build-up processes but may also include other methods that involve forming and adhering portions of the three-dimensional object which do not necessarily correspond to layers of the 3-D image.
Stereolithography involves the formation of three-dimensional objects based on the successive formation of layers of a fluid-like medium adjacent to previously formed layers of medium and the selective solidification of these layers according to cross-sectional data representing successive slices of the three-dimensional object in order to form and adhere successive layers. In conventional stereolithography, a three-dimensional object is constructed by establishing a thin layer of a photocurable composition on the surface of a platform immersed in a bath of the composition and scanning the layer with a laser beam. The laser controls the X, Y dimension of the model. The Z dimension is controlled by incrementally lowering the platform to greater and greater depths after each successive layer corresponding to a cross-section of the model is polymerized or cross-linked.
The production of three-dimensional objects by laminated object manufacturing is characterized by successively cutting object cross-sections having desired shapes and sizes out of sheets of material, and then adhering the resulting cross-sections together to form the three-dimensional object.
Selective deposition modeling (SDM) involves the build-up of three-dimensional objects by selectively depositing solidifiable material on a lamina-by-lamina basis according to cross-sectional data representing slices of the three-dimensional object. Some selective deposition modeling systems can be used in an office environment to produce a prototype. Selective deposition modeling systems are known and include Thermojet and Actua 3-D printing machines. Selective deposition modeling techniques, such as thermal stereolithography, fused deposition modeling and ballistic particle manufacturing, are described in the following references, the disclosures of which are incorporated herein by reference: U.S. Pat. Nos. 5,141,680; 5,121,329; 5,340,433; 5,260,009; 4,665,492; 5,134,569 and 5,216,616.
Compositions useful in thermal stereolithography must be capable of being dispensed from inkjet print heads and other dispensers and also must be capable of forming accurate three-dimensional objects with suitable strength properties after solidification or curing. Inkjet compositions for forming three-dimensional models or images must have a low viscosity at the dispensing temperature and must be stable for prolonged periods of time to be jettable from the printer head of the 3-D printer head.
SUMMARY OF THE INVENTION
The present invention provides a radiation-curable inkjet composition for forming 3-D models or images comprising a semi-crystalline or crystalline, low-shrinkage, radiation-curable oligomeric material, a photoinitiator and one or more diluents. In accordance with one embodiment of the invention, the inkjet composition has a viscosity of between about 10 to about 50 cps at at least one temperature between about 50 to 140° C. In accordance with some embodiments of the invention, the inkjet composition is solid at ambient conditions but forms a flowable liquid when subjected to elevated temperatures. The radiation-cured composition exhibits low-volume shrinkage during the transition from an uncrosslinked solid to a crosslinked solid. Low-shrinkage materials in accordance with the present invention are those exhibiting a volume shrinkage of less than about 7%, preferably less than about 2%. The radiation-cured composition also exhibits the physical strength characteristics necessary to accurately form three-dimensional objects with suitable strength.
The radiation-curable inkjet compositions of the present invention comprise one or more semi-crystalline or crystalline oligomers. The crystalline nature of the material is considered desirable because the inkjet compositions exhibit lower melting point of the solid resin and lower viscosity in the molten state as compared to amorphous materials. In accordance with one embodiment of the present invention, the semi-crystalline or crystalline, radiation-curable material is a methacrylated polyester oligomer that melts at about 70 to 100° C. and has a molten viscosity of under 300 cps at temperatures higher than 120° C. In accordance with another embodiment of the present invention, the semi-crystalline or crystalline radiation-curable material is a methacrylated urethane oligomer that melts at about 60 to 80° C. and has a molten viscosity of under 100 cps at temperatures higher than 120° C.
In addition to the semi-crystalline or crystalline, low-shrinkage, radiation-curable material, the radiation-curable inkjet composition of the present invention also comprises a photoinitiator and a diluent. Photoinitiators useful in the present invention include those typically used in the art to initiate photopolymerization of ethylenically unsaturated compounds. A diluent is included in the radiation-curable inkjet composition to lower the viscosity and/or to provide required properties, such as hardness and strength. Diluents useful in the present invention may be liquid or solid at room temperature and may be reactive or non-reactive diluents.
In another aspect of the present invention, a method for forming at least a portion of a 3-D model or image using a radiation-curable, inkjet composition is disclosed. In general, this method comprises the steps of providing a radiation-curable composition comprising a semi-crystalline or crystalline, low-shrinkage, radiation-curable oligomer material, a photoinitiator and a diluent, wherein the composition is a solid at room temperature; heating the composition to a temperature between about 50 and 140° C. so as to melt the composition; selectively dispensing the composition at a dispensing temperature from about 50 to about 140° C., wherein the composition is selectively dispensed to correspond to a portion of the 3-D model or image; and exposing the selectively dispensed composition to radiation to cure the composition, thereby forming at least a portion of a 3-D model or image. The described method can be repeated to form additional portions of the 3-D model or image.
DETAILED DESCRIPTION OF THE INVENTION
As used herein, ambient conditions refer to room temperature (about 25° C.) and atmospheric pressure. All parts and percentages specified herein are by weight unless otherwise specified. Furtherm
Grinevich Oleg V.
Martin Dustin B.
Mejiritski Alexandre
Neckers Douglas C.
McClendon Sanza L.
Seidleck James J.
Spectra Group Limited, Inc.
Thompson Hine LLP
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