Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Compositions to be polymerized by wave energy wherein said...
Reexamination Certificate
1997-04-30
2001-03-06
Berman, Susan W. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Compositions to be polymerized by wave energy wherein said...
C522S084000, C522S085000, C522S031000, C524S002000, C524S005000, C524S430000, C524S434000, C524S802000, C524S815000, C524S816000, C524S845000, C430S269000, C430S281100, C430S286100
Reexamination Certificate
active
06197843
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to methods for the fabrication of ceramic objects. More specifically, this invention relates to rapid freeform methods which employ a dispersion of ceramic particles in an aqueous photocurable composition.
Prototypes of articles are commonly manufactured to verify the drawings of a computer-aided design of a three-dimensional article before the article is prepared on a commercial scale. Such prototypes may be made by a variety of processes, but the need for faster processes has led to the development of stereolithographic processes employing photocurable polymers. However, it is often desirable to prepare the prototype from the composition from which the final part will be prepared so that the structural properties of the article may be tested.
Prototypes of ceramic articles are typically prepared by tooling the part from a monolithic piece of a fired ceramic or from high volume dispersions of ceramic materials by molding processes such as injection molding, and then sintered. However, these methods do not allow for the preparation of complicated shapes having internal features or small length scales.
SUMMARY OF THE INVENTION
In one aspect, the invention is a high-solids photocurable ceramic composition comprising:
(a) at least 10 percent by volume of water;
(b) at least 0.05 percent by weight of photocurable compounds or polymers that are soluble or dispersible in water; and
(c) at least 45 volume percent of dispersed ceramic particles.
In a second aspect, the invention is a process for preparing ceramic articles which comprises:
(a) applying a layer of a high-solids photocurable ceramic composition to a substrate, the composition comprising:
(1) at least 10 percent by volume of water;
(2) at least 0.05 percent by weight of photocurable compounds which are soluble or dispersible in water; and
(3) at least 45 volume percent of dispersed ceramic particles; and
(b) subjecting the composition to sufficient ultraviolet radiation to react the compounds or polymers sufficiently to form a layer of the photocurable compounds or polymers having the ceramic particles dispersed therein, which are water-insoluble and non-dispersible in water.
It has been discovered that the process of the invention permits the fabrication of ceramic articles from high-solids dispersions of ceramic particles using methods typically employed in stereolithography applications, achieving relatively high curing depths while maintaining relatively precise resolution. These and other advantages of the invention will be apparent from the description which follows.
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Aksay Iihan A
Garg Rajeev
McCann Gordon D
Prud'homme Robert K
Rose Gene D
Berman Susan W.
The Dow Chemical Company
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