JP3451134B2 - Photolytic degreasing equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a degreasing device used in the process of manufacturing powder injection molded parts, and more particularly to a metal powder and / or ceramic powder and at least one photodegradable resin. The present invention relates to a photolytic degreasing device used for photolytically removing an organic binder from a molded body after mixing with an organic binder and injection molding the mixture into a desired shape.

[0002]

2. Description of the Related Art As a method for producing a component having a complicated shape using metal and / or ceramic powder, an organic binder which is a thermoplastic resin is dispersed and mixed with these powders, and the mixture is molded by an injection molding method. Then, the resin contained in the molded body is removed, that is, degreasing is performed, and then the molded body is fired to obtain a desired metal or ceramic part. This powder injection molding method has an advantage over a compression molding method called powder metallurgy in that a product having a three-dimensionally complicated shape can be mass-produced with high dimensional accuracy.

In this powder injection molding method, as a method for removing the organic binder from the molded body, a heat decomposition method (Japanese Patent Publication No. 61-58563, etc.) and a solvent extraction method (Japanese Patent Publication No.
9-27743), etc., a method of lowering the molecular weight of the organic binder by irradiating it with ultraviolet rays, X-rays, electron beams, etc., using a photodegradable resin as the organic binder, or leaving it after the light irradiation. A photolytic degreasing method of thermally decomposing and removing the above organic binder has been proposed and implemented. (JP-A-5
9-199570, JP-A-2-275748, JP-A-3-183704).

Conventionally, the structure of the degreasing device used in this photolytic degreasing method was as follows. FIG. 3 shows a schematic view of a cross section of a conventional photolytic degreasing device. In FIG. 3, the light from the light source 1 is applied to the molded body 6 through the quartz glass 4. Here, as the light source 1, a mercury lamp, a mercury-xenon lamp, a metal halide lamp, or the like is used. The temperature in the device can be heated to any temperature by the heater 7, and the device can be heated by using a vacuum pump attached to the vacuum pump attachment port 8 or by flowing an appropriate gas into the gas inlet 9 and the gas outlet 10. You can set the atmosphere inside. Further, the light irradiation time can be arbitrarily controlled by opening / closing the shutter 5.

Here, the molded body 6 is arranged on the ceramic substrate 11 arranged in the lower part of the inside of the apparatus, and light is irradiated from the upper surface of the molded body. Here, for the ceramic substrate 11, a porous alumina plate or the like that absorbs and holds the low-molecular organic binder was used.

[0006]

However, when the photolytic degreasing apparatus as shown in FIG. 3 is used in the photolytic degreasing method, the surface of the molded body 6 which is in contact with the support is not irradiated with light. Therefore, there is a drawback that decomposition of the organic binder does not proceed from the lower surface of the molded body 6. As a result, the degreasing rate is unevenly distributed depending on the location of the molded product, resulting in defective degreasing such as cracking of the molded product. This is because decomposition of the organic binder does not proceed on the surface not irradiated with light, and a large amount of the organic binder remains, and in the subsequent temperature rising process, the organic binder inside the molded body is rapidly decomposed, As a result, cracking occurred in the molded body due to the rapid generation of the decomposition gas.

In order to solve this problem, it is necessary to irradiate the entire surface of the molded product with light. Therefore,
The object of the present invention is to solve the above problems, by performing light irradiation on the entire surface of the molded body in the degreasing step by photolysis, and by actively removing the low-molecular organic binder, damage and deformation of the molded body, An object is to provide a device for performing photolytic degreasing without causing cracking or the like.

[0008]

In order to achieve the above object, the photolytic degreasing apparatus of the present invention adopts the constitution described below.

The photolytic degreasing apparatus of the present invention irradiates light to a molded body molded from a mixture of sintering powder and an organic binder containing at least one kind of photodegradable resin, and the photodegradable property is obtained. A device used for removing resin, wherein a support for a molded body is installed inside the device, and the support is provided with a heat-resistant grid or a light-transmissive plate and is laid on the plate. Made of ceramic wool, the light source is provided on one of the upper and lower sides of the support table, and the reflector is provided on the other side, or the light source is provided on the upper and lower sides of the support table. Is characterized by.

The present invention will be described in more detail with reference to FIGS. 1 and 2 showing an example of a schematic sectional view of the photolytic degreasing apparatus of the present invention. FIG. 1 is a schematic cross-sectional view of a photolytic degreasing device of the present invention in which a light source 1 is arranged below a supporting base 2 and light is irradiated from below a molded body 6 installed on the supporting base 2. Is. FIG. 2 is a schematic cross-sectional view of the photolytic degreasing device of the present invention in which the light sources 1 are arranged on both upper and lower sides of the support base 2 and light is irradiated from above and below the molded body 6.

Here, the characteristics required for the support base 2 are heat resistance rigidity, absorptivity of a low molecular weight binder, and chemical stability as well as the conventional degreasing jig, and in addition, it efficiently transmits ultraviolet rays. In addition, the weight of the molded body is evenly distributed and loaded to hold the molded body. Here, one feature of the present invention is that the support base 2 is formed of a heat-resistant grid or a light-transmissive plate 2a and a ceramic wool 2b laid thereon. That is, the heat-resistant grid or the light-transmissive plate 2a and the ceramic wool 2b have a function of uniformly distributing and loading the weight of a plurality of molded bodies and transmitting ultraviolet rays. Here, as the heat resistant grid or the heat resistant grid in the light-transmissive plate 2a, a metal such as stainless steel or a ceramic such as alumina can be used. In order to prevent blocking of ultraviolet rays, it is preferable that the lattice is as thin as possible. Further, the spacing of the lattice can be arbitrarily selected depending on the size of the molded body 6. Further, quartz glass or the like can be used as the light-transmitting plate in the heat-resistant grid or the light-transmitting plate 2a of the present invention. Next, the ceramic wool 2b has a thickness that can be spread as thin as about 1 mm and has a shape that allows light to pass through between the fibers, and is made of a material that sequentially absorbs or permeates a low molecular weight organic binder. To be For example, alumina or silica-alumina type ceramic wool can be used.

Here, as shown in FIG. 1, in the photolytic degreasing apparatus of the present invention in which the light source is arranged below the support, the light from the light source 1 passes through the quartz glass 4 and the molded body 6
Of the molded body 6 is also irradiated by the action of the reflection plate 3 arranged in the upper part of the apparatus. As the reflector used in the present invention, a high-purity aluminum plate or the like is used. Further, the same effect can be obtained by disposing the light source 1 in the upper part of the apparatus and disposing the reflection plate 3 in the lower part.

Further, as shown in FIG. 2, it is also possible to arrange light sources on both the upper and lower sides of the support base to irradiate light from the upper and lower sides of the molded body. In the photolytic degreasing device of the present invention in which the light sources are provided on both the upper and lower sides of the support base, it is possible to irradiate light onto the entire surface of the molded body 6 without disposing the reflection plate shown in FIG.

Further, this apparatus uses the shutter 5, the heater 7, the vacuum pump mounting port 8, the gas introduction port 9 and the gas exhaust port 10 as in the conventional photolytic degreasing device, and the atmosphere and temperature and the light inside the device. The irradiation time can be set arbitrarily.

As described above, by using the apparatus of the present invention to irradiate the entire surface of the molded body with light to perform photolytic degreasing, a degreased body having no defects such as breakage, deformation and cracks can be produced. .

[0016]

In the step of removing the organic binder by irradiating light to the molded body molded using the mixture of the sintering powder and the organic binder containing at least one kind of photodegradable resin,
As a means to uniformly irradiate light so that uneven degreasing rate due to the location of the molded body and degreasing failure due to it do not occur, use a jig etc. after irradiating light to a certain part as usual. It is also conceivable that the molded body is turned over and the surface not irradiated with light is irradiated again with light. However, this method not only requires a long time for degreasing, but also moves the molded body in which a part of the organic binder is removed and the shape retention strength is weakened, so that the molded body is easily damaged. Further, a method of irradiating light from above and below using a light-transmitting material such as quartz glass alone for the support of the molded body is also conceivable. However, the support is required to have a function of sequentially absorbing and removing the organic binder whose molecular weight has been reduced by photolysis. That is,
When a material such as quartz glass that does not absorb a low molecular weight binder is used for the support base, the low molecular weight organic binder remains at the portion in contact with the support base, which lowers the degreasing rate It causes problems such as deformation of the.

In the photolytic degreasing apparatus of the present invention, the organic binder is removed by irradiating light to a molded product molded using a mixture of sintering powder and an organic binder containing at least one kind of photodegradable resin. In the process, the heat-resistant grid or light-transmissive plate and the ceramic wool laid on top of the molded product installed on the support that transmits light, and the light sources or reflectors arranged above and below By irradiating light, not only the upper surface but also the lower surface can be irradiated with light, and the organic binder can be uniformly decomposed and removed from the entire surface of the molded body.

Here, the ceramic wool used in the present invention has not only the function of transmitting light, but also the function of absorbing or penetrating the low molecular weight binder component produced by photolysis. Therefore, the low molecular weight component generated by photolysis on the entire surface of the molded body can be removed more quickly from the vicinity of the surface of the molded body. Further, the heat-resistant grid or the light-transmissive plate used in the present invention and the ceramic wool laid on the plate can transmit the light and, at the same time, evenly disperse the weight of the molded body and hold the molded body. it can. Therefore, by using the photolytic degreasing device of the present invention, since the entire surface of the molded body is irradiated with light, the molded body does not move, and the molded body is not damaged.

As described above, by using the photolytic degreasing apparatus of the present invention, it is possible to irradiate the entire surface of the molded product with light and efficiently remove the low-molecularized organic binder component. it can. Therefore, the photodegraded degreased body having no defects such as deformation and cracks can be obtained in a short time without damaging the molded body.

[0020]

EXAMPLES The present invention will be further described below with reference to examples.

Example 1 100 parts by weight of stainless steel powder (SUS316) having an average particle diameter of 12 μm and 7 parts by weight of poly-n-butyl methacrylate as a photodegradable organic binder were used at 160 ° C. using a pressure kneader. After thoroughly melt-mixing, pelletized. Using an injection molding machine with these pellets, molding temperature 160 ° C, injection pressure 1t /
cm ² , 18 mm × 4 mm × 1 mm at a mold temperature of 50 ° C.
A plate-shaped molded body of was obtained.

Next, the organic binder in the molded body was removed by using the photolytic degreasing apparatus of the present invention configured as shown in FIG. The heat-resistant grid or the light-transmissive plate 2a used for the support base 2 is a stainless steel grid in this embodiment, and the grid has a diameter of 300 μm and a size of 3 mm square. Ceramic wool 2
For b, a product made of alumina (trade name: Ruby Bulk Fiber, manufactured by Nichias) was thinly used so as to have a thickness of about 1 mm. Light source 1 is a low-pressure mercury lamp (trade name)
QOL350U-3, 350W x 3 pieces, manufactured by Iwasaki Electric Co., Ltd.)
Was used. Light intensity is calculated by UV integrated intensity meter (trade name: UV
PZ-2, manufactured by Eye Graphics Co., Ltd.). Light intensity at the wavelength of 254nm is 3.2 mW / cm ² on the lower surface of the upper support stand That molded body was 7.0 mW / cm ² on the upper surface of the reflecting plate side or moldings. Using the above-mentioned apparatus and conditions, the molded body was first exposed to 170 ° C. in an argon atmosphere while being irradiated with ultraviolet rays.
The temperature was raised over time and the temperature was maintained for 5 hours. Then 3
The temperature was raised to 00 ° C. in 3 hours, the irradiation of ultraviolet rays was terminated, and the furnace was cooled to obtain a degreased body. In this defatted body,
The removal rate of the organic binder was 80%, and the degreased body was not cracked or swollen.

Next, the degreased body obtained by the photolytic degreasing is placed on an alumina plate, heated in a hydrogen atmosphere from room temperature to 400 ° C. in 1 hour and heated at that temperature for 1 hour, and the rest is left. After decomposing and removing the organic binder of 4
The temperature was raised from 00 ° C to 1350 ° C in 4 hours. Then, the temperature was maintained for 3 hours to obtain a fired body. No defective appearance of the fired body occurred.

(Comparative Example 1) The organic binder was removed from the molded body produced in Example 1 by using a conventional photolytic degreasing apparatus constructed as shown in FIG. The light source is the first embodiment.
The same low-pressure mercury lamp was used. Ceramic substrate 1
For 1, a plate made of porous alumina having a thickness of 4 mm was used.
The light intensity of 254 nm is 7.3 mW / cm on the upper surface of the molded body.
² , the lower surface of the molded body was not irradiated with light. While irradiating with the ultraviolet rays, photodecomposition degreasing was performed under the same atmosphere and temperature rising conditions as in Example 1 to obtain a degreased body. The removal rate of the organic binder in the degreased body was 47%, and in all degreased bodies, cracks and deformations occurred on the lower surface and the side surfaces which were not irradiated with light.

Next, the degreased body obtained by the photolytic degreasing was fired in the same manner as in Example 1 to obtain a fired body. All fired bodies were cracked or deformed due to poor degreasing.

Example 2 To 100 parts by weight of calcium titanate powder having an average particle diameter of 1 μm, 16 parts by weight of poly-α-methylstyrene as a photodegradable organic binder and 6 parts by weight of paraffin wax as a fluidity imparting component. After melt mixing at 150 to 120 ° C. using a pressure kneader,
Pelletized. Using the pellets, an injection molding machine was used to obtain a cylindrical molded body having a diameter of 1 cm and a thickness of 1.5 mm at a molding temperature of 130 ° C., an injection pressure of 1 t / cm ² , and a mold temperature of 20 ° C.

Next, the organic binder in the molded body was removed by using the photolytic degreasing apparatus of the present invention configured as shown in FIG. In the present embodiment, the heat-resistant grid or the light-transmissive plate 2a used for the support 2 was an alumina grid having a grid thickness of 1 mm and a grid size of 5 mm square. Ceramic wool 2b is silica 51
% 49% alumina (trade name: Fineflex bulk fiber, manufactured by Nichias) was used by thinly stretching it to a thickness of about 1 mm. As the light source 1, the same low-pressure mercury lamp as in Example 1 was used, and the light intensity was measured in the same manner as in Example 1. Light intensity at the wavelength of 254nm is, 2.8 mW / cm ² on a support base that is, in the lower surface of the molded body was 6.7mW / cm ² at the upper surface of the reflecting plate side or moldings. Using the above-described apparatus and conditions, the molded body was first irradiated with ultraviolet rays in an argon atmosphere at 16
The temperature was raised to 0 ° C. in 1 hour, and the temperature was maintained for 5 hours. After that, the temperature was raised to 300 ° C. in 3 hours, the irradiation of ultraviolet rays was terminated, and the furnace was cooled to obtain a degreased body. In this degreased body, the removal rate of the organic binder was 75%, and no cracking or swelling was observed in the degreased body.

Subsequently, the degreased body subjected to this photolytic degreasing is placed on an alumina plate, heated in the air from room temperature to 400 ° C. in 1 hour, and heated at that temperature for 1 hour, and the rest is left. After decomposing and removing the organic binder of 4
The temperature was raised from 00 ° C to 1250 ° C in 2 hours. Then, the temperature was maintained for 1.5 hours to obtain a fired body. No defective appearance of the fired body occurred.

(Comparative Example 2) The organic binder was removed from the molded body produced in Example 2 by using a conventional photolytic degreasing apparatus constructed as shown in FIG. As the ceramic substrate 11, a plate made of porous alumina having a thickness of 4 mm was used as in Comparative Example 1. The light intensity of 254 nm was 7.0 mW / cm ² on the upper surface of the molded body, and the lower surface of the molded body was not irradiated with light. While irradiating with the ultraviolet rays, photodecomposition degreasing was performed under the same atmosphere and temperature rising conditions as in Example 2 to obtain a degreased body. In this degreased body, the removal rate of the organic binder was 40%, and some of the degreased bodies were deformed on the lower surface and the side surfaces which were not irradiated with light.

Next, the photodegraded and degreased compact was fired in the same atmosphere and temperature rising conditions as in Example 2 to obtain a fired body. Some of the fired bodies were deformed due to poor degreasing.

Example 3 With respect to 100 parts by weight of iron powder having an average particle size of 1.5 μm, 7.3 parts by weight of polymethyl methacrylate as a photodegradable organic binder and 3.7 parts by weight of carnauba wax as a fluidity imparting component. The parts were melt mixed at 160 ° C. to 180 ° C. using a pressure kneader and then pelletized. Using an injection molding machine using the pellets, a molding temperature of 170 ° C., an injection pressure of 1 t / cm ² , and a mold temperature of 20.
A columnar molded body having a diameter of 1 cm and a thickness of 1.5 mm was obtained at ℃.

Next, the organic binder in the molded body was removed by using the photolytic degreasing apparatus of the present invention configured as shown in FIG. As the heat-resistant grid or the light-transmissive plate 2a used for the support base 2, a quartz glass plate having a thickness of 5 mm was used in this embodiment. The ceramic wool 2b was made of alumina (trade name: Ruby Bulk Fiber, manufactured by Nichias Co.) and was thinly used to have a thickness of about 1 mm. As the light source 1, low-pressure mercury lamps (trade name: QOL350U-3, 350W x 2 each, manufactured by Iwasaki Electric Co., Ltd.) were used above and below the furnace body, and the light intensity was measured in the same manner as in Example 1. 5.3 mW / cm ² light intensity in the upper surface of the molded article at the wavelength of 254 nm, was 4.6 mW / cm ² at the lower surface. Using the above-described apparatus and conditions, the molded body was irradiated with ultraviolet rays for 12 hours in an argon atmosphere.
The temperature was raised to 0 ° C. in 1 hour, and the temperature was maintained for 5 hours. Then, the temperature was raised to 400 ° C. in 3 hours, the irradiation of ultraviolet rays was terminated, and the furnace was ordered to obtain a degreased body. In this degreased body, the removal rate of the organic binder was 92%,
No cracking or swelling was observed in the degreased body.

Subsequently, the degreased body subjected to the photolytic degreasing is placed on an alumina plate, heated in a hydrogen atmosphere from room temperature to 400 ° C. in 1 hour, and heated at that temperature for 1 hour. After decomposing and removing the organic binder of 4
The temperature was raised from 00 ° C to 1200 ° C in 3 hours. Then, the temperature was maintained for 2 hours to obtain a fired body. No defective appearance of the fired body occurred.

(Comparative Example 3) With respect to the molded body produced in Example 3, the organic binder was removed in the same manner as in Example 3 using the photolytic degreasing device configured as shown in FIG. However, instead of the quartz glass having a thickness of 5 mm and the ceramic wool made of alumina thereon, a plate made of porous alumina was used for the support base 2 of the molded body. Two
The light intensity of 54 nm is 5.3 mW / cm ^{2 on} the upper surface of the molded body.
And the lower surface was not irradiated with light. Photoirradiation was performed under the same atmosphere and temperature rising conditions as in Example 3 while irradiating the ultraviolet ray having this light intensity to obtain a degreased body. In this degreased body, the removal rate of the organic binder was 90%, but in some degreased bodies, cracks occurred on the lower surface that was not irradiated with light.

Next, the photo-decomposed and degreased degreased body was fired in the same atmosphere and temperature rising conditions as in Example 3 to obtain a fired body. Some of the fired bodies were cracked due to poor degreasing.

From the results of Example 1 and Comparative Example 1, Example 2 and Comparative Example 2, and Example 3 and Comparative Example 3, the removal rate of the organic binder was improved by using the photolytic degreasing apparatus according to the present invention. It is clear that the degreasing can be performed and the degreasing failure can be prevented.

[0037]

EFFECTS OF THE INVENTION According to the present invention, a molded body molded using a mixture of a sintering powder and an organic binder containing at least one kind of photodegradable resin is irradiated with light to emit the organic binder from the molded body. When removing, a support for a molded body made of a heat-resistant grid or a light-transmissive plate and a ceramic wool laid on the plate is arranged, and the light source is provided on one of the upper and lower sides of the device and the reflection plate is provided on the other side. By using a photolytic degreasing device in which a light source is provided on both the top and the bottom, it is possible to perform light irradiation on the entire surface of the molded body,
Furthermore, the low-molecular weight binder component produced by photolysis can be quickly removed. This causes damage in a short time,
It is possible to obtain a degreased body without defects such as deformation and cracks,
Further, it is possible to obtain a fired body having no poor appearance.

[Brief description of drawings]

FIG. 1 is a schematic view of a cross section of a photolytic degreasing device of the present invention.

FIG. 2 is a schematic view of a cross section of the photolytic degreasing device of the present invention.

FIG. 3 is a schematic view of a cross section of a conventional photolytic degreasing device.

[Explanation of symbols]

1 light source 2 support 2a Heat-resistant grid or light-transmissive plate 2b Ceramic wool 3 reflector 4 quartz glass 5 shutters 6 molded body 7 heater 8 Vacuum pump mounting port 9 gas inlet 10 gas outlet 11 Ceramic substrate

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B22F 3/10 C04B 35/638 F27B 17/00

Claims (3)

(57) [Claims] 1. A photodecomposition for removing an organic binder from a molded body, which is molded by using a mixture of a sintering powder and an organic binder containing at least one kind of photodegradable resin, to irradiate the molded body with light. A degreasing device, wherein a support for a molded body is installed inside the photolytic degreasing device, and the support comprises a heat-resistant grid or a light-transmissive plate and ceramic wool laid on the plate. The photolytic degreasing device, characterized in that a light source is provided on one of the upper and lower sides of the support, and a reflecting plate is provided on the other side. 2. The photolytic degreasing device according to claim 1, wherein a light source is arranged below the support base, and a reflecting plate is arranged above the support base. 3. A photodecomposition which removes an organic binder from the molded body by irradiating a molded body molded with a mixture of a sintering powder and an organic binder containing at least one kind of photodegradable resin with light. A degreasing device, wherein a support for a molded body is installed inside the photolytic degreasing device, and the support comprises a heat-resistant grid or a light-transmissive plate and ceramic wool laid on the plate. And a light source disposed above and below the support base.