Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive...
Reexamination Certificate
2000-07-07
2002-08-13
Hamilton, Cynthia (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
C430S280100, C430S283100, C264S401000, C522S167000
Reexamination Certificate
active
06432607
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a photocurable resin composition and to a process for producing a three-dimensional object from the photocurable resin composition. More specifically, it relates to a photocurable resin composition which can give moldings and three-dimensional objects having excellent dimensional accuracy with a small volume shrinkage factor at the time of photo curing and excellent heat resistance with a high heat distortion temperature as well as excellent transparency and mechanical properties such as tensile strength and to a process for producing a three-dimensional object from the photocurable resin composition by stereolithography.
PRIOR ART
Generally speaking, liquid photocurable resin compositions are widely used as coatings (especially hard coatings), photoresists, dental materials and the like. Special attention has recently been paid to a process for optically shaping a photocurable resin composition into a three-dimensional object based on data input into a 3-D CAD. As for art of stereolithography, JP-A 56-144478 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”) discloses stereolithography method for producing a three-dimensional object by repeating the step of curing a liquid photocurable resin with a required amount of controlled light energy to form a thin layer, the step of further supplying a liquid photocurable resin on the top of the thin film and the step of exposing the photocurable resin to light under control to cure it so as to form a laminate. JP-A 60-247515 proposes its basic application method. Thereafter,many proposals for art of stereolithography have been made by JP-A 62-35966, JP-A 1-204915, JP-A 2-113925, JP-A 2-145616, JP-A 2-153722, JP-A 3-15520, JP-A 3-21432 and JP-A 3-41126.
A typical process for optically producing a three-dimensional object is a process for producing a three-dimensional object having a final shape by repeating lamination operation consisting of the steps of exposing selectively the liquid surface of a liquid photocurable resin composition in a shaping bath to ultraviolet laser light which is controlled by a computer to cure it to a predetermined thickness so as to obtain a desired pattern, supplying a liquid resin composition of one layer onto the cured layer and exposing it to ultraviolet laser light to cure it so as to form another cured layer on the previous cured layer. This process has recently been attracting special attention because a three-dimensional object of interest can be easily produced in a relatively short period of time even though the shape of the object is very complex.
A photocurable resin composition comprising a curable resin such as an unsaturated polyester, epoxy (meth)acrylate, urethane (meth)acrylate or (meth)acrylic ester monomer, and a photopolymerization initiator is widely used in coatings, photoresists, dental materials and the like.
A photocurable resin composition used in stereolithography method comprises at least one photopolymerizable compound such as a photopolymerizable modified (poly)urethane (meth)acrylate-based compound, oligoester acrylate-based compound, epoxy acrylate-based compound, epoxy-based compound, polyimide-based compound, aminoalkyd-based compound or vinyl ether-based compound as the main component and a photopolymerization initiator. In recent years, JP-A 1-204915, JP-A 1-213304, JP-A 2-28261, JP-A 2-75617, JP-A 2-145616, JP-A 3-104626, JP-A 3-114732 and JP-A 3-114734 disclose various improving technologies.
The photocurable resin composition used for the production of three-dimensional objects must be a low-viscosity liquid, have small volume shrinkage at the time of curing and give a three-dimensional object obtained by photo curing having excellent mechanical properties from the viewpoints of handling properties, shaping speed and shaping accuracy. In recent years, demand and application of three-dimensional objects formed by stereolithography have been expanding and three-dimensional objects having excellent heat resistance with a high heat distortion temperature and excellent transparency in addition to the above characteristic properties have been in demand according to application purpose. Three-dimensional objects having small volume shrinkage at the time of photo curing, high heat distortion temperature and excellent transparency are valued highly as three-dimensional objects used for the design of a complicated heating medium circuit and three-dimensional objects used for the analysis of the behavior of a heating medium having a complicated structure.
To obtain a three-dimensional object having improved heat resistance by stereolithography, there have been studied a method for introducing a benzene ring into the molecule of a photocurable resin, a method for increasing the crosslinking density of an optically cured product, and the like. However, heat distortion temperature under high load is 70 to 80° C. at the best in these cases. Therefore, these methods are unsatisfactory in terms of heat resistance. In addition, when the heat resistance of an optically cured product is to be improved, volume shrinkage at the time of curing becomes large, thereby reducing dimensional accuracy.
Generally speaking, volume shrinkage at the time of curing tends to become large by though the improvement of heat resistance is expected from increasing the crosslinking density of a photocurable resin composition an increase in the crosslinking density. Therefore, the improvement of heat resistance and the reduction of volume shrinkage at the time of curing are contradictory to each other. As one of means of breaking through this contradictory relationship, the inventors of the present invention have developed and proposed a photocurable resin composition prepared by blending a filler into a specific photocurable resin (see JP-A 5-196691 and JP-A 5-196692). When this photocurable resin composition is used, a shaped object having excellent heat resistance and a small volume shrinkage factor is obtained, which breaks through the above contradictory relationship. When the present inventors have conducted further studies based on the above invention, it has been found that there is still room for improvement in terms of handling properties at the time of shaping because the photocurable resin composition shows high viscosity and thixotropy from flowability and viscosity thereof owing to the filler contained therein.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a photocurable resin composition which is excellent in handling properties because it is a:low-viscosity liquid, can be optically cured in a short period of time, has excellent dimensional accuracy with small volume shrinkage at the time of photo curing, and can give moldings, three-dimensional objects and other cured products having excellent heat resistance with a high heat distortion temperature as well as excellent transparency and mechanical properties such tensile strength.
It is another object of the present invention to provide a process for producing a three-dimensional object from the photocurable resin composition of the present invention by stereolithography.
Other objects and advantages of the present invention will become apparent from the following description.
According to the present invention, firstly, the above objects and advantages of the present invention are attained by a photocurable resin composition comprising:
(i) at least one imidated acrylic compound represented by the following formula (I):
wherein R
1
is an alicyclic group which may be substituted, an aromatic group which may be substituted or an aliphatic group which may be substituted, R
2
is a residual group of aminoalcohol, R
3
is hydrogen atom or methyl group, and n is 1 or 2;
(ii) at least one polymerizable compound selected from the group consisting of a radical polymerizable compound and a cationic polymerizable compound other than the above imidated acrylic compound; and
(iii) a photopolymerization initiator, the we
Hagiwara Tsuneo
Ohtake Makoto
Tamura Yorikazu
Anderson Kill & Olick
Hamilton Cynthia
Lieberstein Eugene
Meller Michael N.
Teijin Seiki Co. Ltd.
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