JPH0224127A - Optical shaping method - Google Patents

Abstract

PURPOSE:To mitigate shrinkage stress of cure, by a method wherein thermosetting resin is used together with photosetting resin and a process of the cure is divided into two stages of photosetting and thermosetting ones. CONSTITUTION:A mixture of thermosetting resin and photosetting resin 12 is held into a vessel 11 and a light transmission window 13, a light emission part 15 applying light flux to the window 13, an optical fiber 16, an X-Y moving device 17 of the light emission part and a light source 20 are provided on the bottom of the vessel. Only photosetting resin is cured with irradiation with light, to begin with, shrinkage stress is absorbed through dispersion and a primary cured body which hardly generates the shrinkage stress is obtained. Then the same is taken out of a device, the primary cured body is heated by oven heating or arranging a heater around the some and uncured thermosetting resin is cured. This shrinkage stress hardly occurs even in the second curing process so long as the uncured resin exist on the circumference at the time of spreading of cure. The shrinkage stress is generated in an extremely short period of time at the last stage of a curing process and shrinkage stress itself also becomes extremely little.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical modeling method for manufacturing a cured body of a desired shape by irradiating a photocurable resin with light, and particularly relates to an optical modeling method that uses a thermosetting resin in combination. , relates to an optical modeling method in which shrinkage stress during curing is alleviated by dividing the curing process into two stages: photocuring and thermosetting.

[Prior art] A light beam is irradiated onto a photocurable fluid material such as a photocurable resin,
The irradiated part is cured, and this cured part is made to continue in the horizontal direction, and a photocurable fluid material is further supplied above it and cured in the same way, thereby making the cured body continuous in the vertical direction. An optical modeling method for manufacturing a cured body of a desired shape by repeating the process is disclosed in Japanese Patent Application Laid-Open No. 60-2475.
No. 15, No. 62-35966, No. 62-101408, etc. In addition, light is irradiated through a modeling mask having a slit corresponding to one cross section of the cured object in the desired shape to cure the material, and then an uncured photocurable fluid material is placed on the cured layer and the material is used for modeling. There is also an optical modeling method in which a cured body of the desired shape is manufactured by replacing the mask with one that has a slit corresponding to one cross section adjacent to the height direction of the cured body of the desired shape, and repeating the process of irradiating light again. publicly known (for example, the above-mentioned Japanese Patent Application Laid-Open No. 62-3596)
No. 6).

[Problems to be Solved by the Invention] Since the photocurable resin shrinks during curing, it is important to reduce this shrinkage stress in order to improve the precision of the shaped object and prevent cracks.

[Means for Solving the Problems] The optical modeling method of the present invention irradiates a mixture of a photocurable resin and a thermosetting resin with light, and hardens the photocurable resin in the portion irradiated with the light. In addition, a first curing step in which the cured product is stacked to form a three-dimensional object approximately in the desired shape, and a second curing step in which the three-dimensional object is heated to harden the thermosetting resin contained in the three-dimensional object.
A curing step.

[Function] In the present invention, the three-dimensional object obtained in the first curing step is obtained by curing a photocurable resin by irradiating light. In this way, when only the photocurable resin is cured, the shrinkage stress due to curing is dispersed and absorbed by the uncured thermosetting resin, so in the first curing step, The cured solid body (hereinafter sometimes referred to as "primary cured body") generates almost no shrinkage stress as a whole.

).

In the second curing step, heat is applied to the primary cured product obtained in the first curing step to harden the uncured thermosetting resin. By going through this second curing step, a hardened solid with high strength is obtained.

Also in this second curing step, when curing propagates,
As long as there is uncured thermosetting resin around it,
Almost no shrinkage stress occurs in the hardening progressing region. As described above, according to the method of the present invention, shrinkage stress occurs during an extremely short period at the end of the curing process, and the shrinkage stress itself has an extremely small value.

[Example] FIGS. 1 to 4 are cross-sectional views showing an example of an apparatus for carrying out the first curing step of the present invention.

In the apparatus shown in FIG. 1, a container equipped with a stirrer 10]1
A mixture 12 of thermosetting resin and photocuring resin is housed inside. A light transmitting window 13 made of a light transmitting plate such as glass is provided on the bottom of the container 11, and a light emitting section 15 with a built-in lens and an optical fiber 16. An optical system including an X-Y9 moving device 17 for moving the light emitting section 15 in the X-Y direction (X and Y are two orthogonal directions) in a horizontal plane, a light source 20, etc. is provided.

A base 21 is installed inside the container 11, and the base 21 can be raised and lowered by an elevator 22. These x
-y'8 The moving device 17 and the elevator 22 are controlled by a computer 23.

When producing a cured body using the above device, first the base 21
is positioned slightly below the transparent window 13, and the light beam 14 is scanned along the horizontal cross section of the target object. This scanning is performed by a computer-controlled X-Y movement device 17.

After irradiating the entire horizontal cross section of the target shape (in this case, the part corresponding to the bottom or top surface), the base 2
1 is slightly raised to flow the mixture of uncured thermosetting resin and photocurable resin between the cured product 24 and the base 21, and then the same light irradiation as above is performed. By repeating this procedure, a primary cured product having an objective shape can be obtained as a multilayer laminate.

In the above embodiment, a transparent window is provided on the bottom of the container so that light is irradiated from below the container, but in the present invention, a transparent window is provided on the side of the container 11, and light is emitted from the side of the container 11. It is also possible to irradiate. In this case, the base may be gradually moved laterally during the molding process.

In the above embodiment, the light is scanned by moving the optical fiber in the X-Y direction, but as shown in Figure 3 below, the light from the light source is reflected by a mirror and then converged by a lens. An optical system that irradiates the photocurable resin may also be used. In this case, the light beam can be scanned by rotating the mirror.

Further, the present invention may be applied to a known mask method, and a mask 26 having a slit 25 corresponding to the cross section of the target shape may be used, for example, as shown in FIG. Reference numeral 27 indicates a parallel light beam, and other reference numerals in FIG. 2 indicate the same members as in FIG. 1.

Although the apparatus shown in FIGS. 1 and 2 is configured to irradiate light from below the container, in the present invention, light may be irradiated from the upper opening of the container. 's
The apparatus shown in FIGS. 3 and 4 is of a type that irradiates light from above the container.

In the apparatus shown in FIG. 3, a lens 28, a mirror 29, a mirror rotation drive device 29a, a light source 20, etc. are used to irradiate the light beam 14 toward the liquid surface 12a of the mixture 12 of thermosetting resin and photocurable resin. An optical system consisting of the following is provided.

A table 21 is installed inside the container 11, and the base 21
can be raised and lowered by an elevator 22. These ib device 29a and elevator 22 are controlled by a computer 23.

When producing a primary cured body using the above-mentioned apparatus, first, the substrate 21a on the base 21 is positioned slightly below the liquid level 12a, and the light beam 14 is scanned along the horizontal cross section of the target shape. This scanning is performed using a computer-controlled mirror 29.
This is done by rotating the

After irradiating the entire horizontal cross section of the target shape (in this case, the part corresponding to the bottom surface), the base 21 is lowered slightly, and the uncured thermosetting resin and the light are placed on the cured material 24. After flowing the mixture with the curable resin, the same light irradiation as above is performed. By repeating this procedure, a primary cured product having the desired shape can be obtained.

In the above embodiment, the base 21 is gradually lowered, but on the other hand, the liquid level 12a may be gradually raised by adding a mixture of a thermosetting resin and a photocurable resin.

The apparatus shown in FIG. 4 uses a mask 26 having a slit 25 corresponding to the cross section of the object. Reference numeral 27 indicates a parallel light beam. Other symbols in FIG. 4 indicate the same members as in FIG. 3.

In the present invention, in such a first curing step, only the photocurable resin is cured by irradiation with light to produce a primary cured product having approximately the desired shape.

Therefore, the mixing ratio of thermosetting resin and photocuring resin is
It is necessary that the ratio be such that the three-dimensional shape obtained by curing only the photocurable resin can maintain its shape.

This mixing ratio is determined as appropriate, taking into account the physical properties of the thermosetting resin and photocurable resin used, as well as the three-dimensional shape and size, but in normal cases, it is based on 100 parts by weight of the photocurable resin. The thermosetting resin is preferably 3 to 40 parts by weight.

After obtaining the primary cured product having almost the desired shape in the first curing step in this way, it is taken out of the device and the second cured product is removed.
In the curing step, heat is applied to the entire primary cured body to cure the uncured thermosetting resin.

In this case, there are no particular restrictions on the heating method; if the primary cured product is small, the primary cured product may be heated in an oven, or if it is large, the primary cured product may be heated by heating it. A method of heating by disposing a heating device such as a heater can be adopted.

The heating temperature is the curing temperature of the thermosetting resin used, and the heating time is appropriately determined depending on the size and shape of the three-dimensional object, the mixing ratio of the thermosetting resin, and the like.

As a result of the second curing step, the cured three-dimensional solid has a small curing shrinkage stress, and the shrinkage stress is evenly distributed throughout the solid, and has excellent dimensional stability and shape stability.

In the present invention, various substances that are cured by light irradiation can be used as the photocurable resin, such as modified polyurethane methacrylate, oligoester acrylate, urethane acrylate, epoxy acrylate, photosensitive polyimide, and amino alkyd. I can do it.

As the light, various types of light such as visible light and ultraviolet light can be used depending on the photocurable resin used. The illumination may be regular light, but laser light has the advantage of increasing the energy level, shortening the molding time, and improving the molding accuracy by utilizing good light focusing. .

The thermosetting resin to be mixed with the photocurable resin is not particularly limited, and epoxy resins, melamine resins, urea resins, phenol resins, urethane resins, alkyd resins, unsaturated polyesters, and the like can be used. In the present invention,
Epoxy resins are preferred in terms of compatibility with photocurable resins.

Since these thermosetting resins are generally cheaper than photocuring resins, in the present invention, by using thermosetting resins in combination, the amount of photocuring resins used is relatively reduced, thereby reducing material costs. It also has the effect of being able to.

[Effects of the Invention] As described above, according to the present invention, it is possible to reduce the shrinkage stress generated in the cured body in the optical modeling method and to uniformly disperse the shrinkage stress throughout the cured body. Therefore, it is possible to produce a highly accurate model without cracks and with almost no dimensional errors due to shrinkage.

[Brief explanation of the drawing]

1 to 4 are longitudinal sectional views of the apparatus employed in the embodiment method. 2...Mixture of thermosetting resin and photocurable resin, 4.
...Light flux, 16...Optical fiber 0...Light source, 21...Base, 2...Elevator. Agent Patent Attorney Tsuyoshi Shigeno Figure 3 zl Figure 4 Fq

Claims (1)

[Claims] (1) A mixture of a photocurable resin and a thermosetting resin is irradiated with light to harden the photocurable resin in the irradiated areas, and the cured product is stacked to form a three-dimensional object with approximately the desired shape. An optical modeling method comprising: a first curing step of heating the three-dimensional object to harden a thermosetting resin contained in the three-dimensional object.