Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Forming nonplanar surface
Reexamination Certificate
2002-05-31
2004-08-24
Duda, Kathleen (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Forming nonplanar surface
C430S396000, C264S401000
Reexamination Certificate
active
06780572
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical lithography using a photocurable component for producing a three-dimensional article.
2. Background Art
Optical lithography, as indicated by the name, in a method comprising successively scanning a liquid photocurable component with a laser beam without using a mould at all, and curing/laminating resin layers to eventually produce a three-dimensional article (Yoji Maritani, et al., “Optical Lithography-Three-Dimension Plotter using Laser”, Nikkan Kogyo Newspaper). According to this method, for example, formed articles such as a skull model that could be made by utilizing results of CT scanning, which are unable to be made by the conventional extrusion or other plastic forming, can be made with perfect ease. Furthermore, with the background of the rapid prototyping receiving much attention at home and abroad in recent years, the optical lithography has become one of the typical forming methods.
Herein, more specifically describing the optical lithography, according to this optical lithography, the formation of a three-dimensional article is carried out by pattern irradiation of light on the surface of a resin composition for optical lithography contain a photocurable component in order to form a cured resin layer corresponding to the pattern, and lamination of such layers to form the three-dimensional shape with a plurality of such cured resin layers. Therefore, a three-dimensional article is formed by analyzing a three-dimensional shape of the article with a computers preparing and accumulating a plurality of data of sliced parts of the shape, radiating ultraviolet laser on a surface of each layer of resin composition for optical lithography according to the data of each layer in the order, and thereby forming photocured resin composition layers one after another.
For example, in the Japanese Patent Laid-open Publication No. Sho56-144478, a method for forming a three-dimensional article has been disclosed, wherein the method comprises placing a liquid photocurable component in a vessel, selectively irradiating the surface of the photocurable component by scanning an exposure means provided on the upper part of the vessel to form a cured resin layer, supplying the photocurable component for one layer over this cured rein layer to form a liquid resin layer, selectively irradiating the surface thereof with light to laminate a fresh cured resin layer as a unit over the previously formed cured resin layer was to continue with each other, and repeating the supply of the photocurable component and irradiation with light predetermined times.
In the conventional optical lithography apparatuses, usually using the ultraviolet laser, a selective drawing of pattern is arranged to be performed for every layer in a rater scanning system. However, in this method, there are problems such as non-uniform resin shrinkage and non-uniform curing depth in cured layers caused by scanning intervals and power instability of laser. Furthermore, there is also another problem that, due to the curing/shrinkage characteristics of rein, shrinkage occurs somewhat after the laser drawing so that shrinkage proceeds with time according to the laser drawing traces, resulting in the generation of internal stress to become liable to form warps in cured layers.
Furthermore, there is yet another problem that, due to not only the low energy efficiency of laser but also especially a short life time of a laser generator to emit the ultraviolet ray required to cure the photocurable component, the continuous and large-scale forming of articles by optical lithography is disadvantageous in terms of cost.
Thus, there has been proposed a method for selectively irradiating the surface of photocurable component through a predetermined mask pattern with the parallel ultraviolet ray emitted from a mercury lamp, etc. For example, in the Japanese Patent Laid-open Publication No. Hei2-78531, as a method for selectively irradiating the surface of photocurable component with light, a method for exposing the surface to light through a mask pattern, which selectively transmits light, has been disclosed.
However, in such a method using mask, there in a problem that said method is uneconomical after all because of the requirement of a great number of mask patterns. In addition, there is another problem that the light diffraction occurs at the time of light transmission through the mask to blur the designed pattern so that the pattern with fine precision cannot be formed. Furthermore, a large number of mask patterns are generally prepared by drawing each of them with toner every one layer on a transparent glass plate, or by forming a pattern every one layer with the liquid crystal shutter. In these cases, there are problems that ultraviolet ray cannot be completely shut out at critical portions, and also that the liquid crystal and glass plate tend to be worn out with ultraviolet ray so that they cannot stand a long-term use and are not suitable for forming articles by optical lithography on a large scale.
SUMMARY OF THE INVENTION
In view of the above-described problem, the present invention has been made aiming at providing an optical lithography using a mask pattern for producing a large quantity of three-dimensional articles rapidly with high precision.
In order to solve the above-described problems, an optical lithography according to this invention is characterized in that a predetermined mask pattern is drawn directly on the surface of a resin composition for optical lithography to be irradiated from above with light, thereby preventing the decline in precision due to the diffraction of irradiation light, and in that a resin composition for optical lithography is further laminated to be photocured without removing the mask pattern, thereby overcoming difficulties in the adjustment of photocuring in the depth direction that have been the drawback in optical lithography.
Optical Lithography According to this Invention
More specifically, the present invention provides the following optical lithography.
(A1) An optical lithography for forming a three-dimensional article composed of multiple cured resin layers by irradiating light over a mask pattern previously drawn on a surface of a resin composition for optical lithography containing a photocurable component, and repeating such irradiating step to form a cured resin layer corresponding to the drawn pattern, wherein the lithography is characterized by the light irradiation over the predetermined mask pattern that is drawn directly on the surface of the resin composition for optical lithography. In this invention, the rapid gelation described below may be preferable, but is not essential (methods according to the procedures described in Japanese Patent Laid-open Publication No. Hei9-70897, Japanese Patent Laid-open Publication No. Sho56-144478, etc. may be applied: that is, a method of irradiating a resin composition for optical lithography over a mask pattern drawn directly on the composition after solidifying the resin composition by cooling it below a room temperature and a method of irradiating light over a mask pattern directly drawn on a surface of the resin composition while it still has fluidity.).
(A2) An optical lithography for forming a three-dimensional article composed of multiple cured resin layers by irradiating light over a mask pattern previously drawn on a surface of a resin composition for optical lithography containing a photocurable component, and repeating irradiating step to form a cured resin layer corresponding to the drawn pattern, wherein the optical lithography is characterized in that a resin composition capable of making a reversible and rapid sol-gel phase transition with some physical stimulus is employed as the resin composition for optical lithography, and wherein the optical lithography comprises gelating rapidly the resin composition for optical lithography by applying “some physical stimulus”, directly drawing a mask pattern on the surface of the gelated
Kamimura Akiya
Murakami Tamotsu
Duda Kathleen
Toudai TLO, Ltd.
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