JP2000204402A - Aqueous solvent extraction from powder injection-formed body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute quick extraction without breaking a formed body in the case of extracting organic binder with water or an aqueous solvent consisting essentially of water. SOLUTION: In the case of extraction and degreasing of the organic binder from the injection-formed body 1 mixed with powder and the organic binder by using, the water or aqueous solvent consisting essentially of water, ultrasonic wave irradiation is executed by using an ultrasonic generator 4 which jetting bubble from a diffusing tube 6 so as to enclose the whole formed body 1 in the state of dipping the formed body 1 into the solvent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a powder injection molded article obtained by extracting and degreasing the organic binder from water and a solvent containing water as a main component from a molded article obtained by mixing a powder and an organic binder and injection molding. And an aqueous solvent extraction method.

[0002]

2. Description of the Related Art In general, in the injection molding of powder, an organic binder is mixed with powder such as metal powder, ceramic powder and cermet powder in order to impart fluidity and pressure moldability. After the injection molding, it is removed by degreasing prior to the sintering step. Conventional degreasing methods include: 1) a method in which an organic binder is dissolved, evaporated or decomposed to evaporate by heating the molded body, and 2) a method in which the organic binder is extracted from the molded body using a solvent.

In the method 1), first, the binder coating the powder is dissolved, and the weight of the injection molded body is added, and the injection molded body becomes structurally unstable. The pressure at the time of decomposition and vaporization is applied, causing collapse of the load and causing deformation of the molded body. Further, if the temperature at the time of heating is increased in order to promote the removal of the binder, the binder is boiled and vaporized, and swelling and cracks are generated. Therefore, in order to prevent the generation of defects in the degreasing process, it is necessary to slowly remove the binder, and there is a problem that a very long degreasing time is required.

On the other hand, in the method 2), a part of the organic binder is extracted and removed with a solvent at a low temperature not higher than the deformation temperature of the molded body, so that the remaining organic binder is removed from the removed organic binder. There is an advantage that the evaporative gas is easily released and swelling and cracks are less likely to occur. However, organic solvents such as hydrocarbons and halogenated hydrocarbons generally used as solvents are expensive and harmful to the human body.

In order to solve such a problem, Japanese Patent Publication No. 6-53884 discloses that an organic binder contains a water-soluble thermoplastic organic polymer and a water-insoluble thermoplastic organic polymer. As a degreasing treatment using an organic binder, a degreasing method has been proposed in which an injection molded article is brought into contact with water to extract a water-soluble thermoplastic organic polymer, and then the remaining organic binder is removed by heating.

Further, in the method described in Japanese Patent Publication No. 6-53884, in order to increase the extraction rate of the water-soluble thermoplastic organic polymer and perform degreasing in a short time,
A method in which low-concentration water is supplied into the system while partially discharging the solvent water (Japanese Patent Publication No. 6-89371);
A device in which water in contact with a molded body is fluidized by stirring, flowing water, ultrasonic waves, or the like (Japanese Patent Publication No. 6-89372) has been proposed.

[0007]

However, the method of supplying low-concentration water into the system described in JP-B-6-89371 and the stirring or running of water described in JP-B-6-89372 are described. In this method, it is difficult to uniformly treat a large number of works (molded bodies) with a low-concentration solvent, and especially when the work is a thick-walled product, the mass transfer inside the work is slowed, thereby increasing the extraction speed. However, there is a problem that there is a limit. In addition, the above-mentioned
The method using an ultrasonic wave described in JP-89-37272 has the following problems. (1) Due to the degassing effect of the ultrasonic waves, the solvent is partially evaporated to form bubbles, and when the bubbles are broken, strong cavitation is generated to bring about a large negative pressure effect. Although the extraction is promoted by the negative pressure effect, the sound pressure level at which the extraction promotion effect can be expected is relatively high, and at this sound pressure level, the work is damaged. In addition, cavitation hardly occurs at a level at which the work is not damaged, and the effect of promoting extraction cannot be expected. (2) In practice, the number of ultrasonic generators is limited, and there may be shaded parts such as workpieces and jigs, and interference or resonance of ultrasonic waves may affect many workpieces or one workpiece. It is impossible to irradiate ultrasonic waves at a uniform intensity level for each of the above-mentioned parts. Therefore, the sound pressure level distribution varies, and it is difficult to obtain the extraction promoting effect only by the ultrasonic waves.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and when extracting an organic binder with water or a solvent containing water as a main component, the molded body is rapidly extracted without damaging it. It is an object of the present invention to provide a method for extracting a powder injection molded article with an aqueous solvent which can be carried out.

[0009]

Means for Solving the Problems and Action / Effect In order to achieve the above object, a method for extracting a water-based solvent from a powder injection-molded article according to the present invention comprises molding a mixture of a powder and an organic binder by injection molding. An aqueous solvent extraction method of a powder injection molded article, wherein the organic binder is extracted and degreased with water or a solvent containing water as a main component, from the body, wherein the molded article is entirely immersed in the solvent. It is characterized in that ultrasonic irradiation is performed while blowing bubbles so as to wrap.

According to the present invention, at the time of extraction with a solvent, ultrasonic irradiation is performed while blowing a foam so as to wrap the entire molded body while the molded body is immersed in the solvent. Therefore, since many dissolved gases coexist in the solvent, the cavitation generated when the bubbles are broken is weakened by the elastic compression effect of the dissolved gases and the bubbles, and is relatively small for the molded body. A negative pressure effect will result. In other words, the sound pressure level at which cavitation occurs is lower than when the solvent is degassed by using only ultrasonic waves. As a result, it is possible to generate cavitation at a level that does not damage the molded body, and the negative pressure effect of this cavitation causes the high-concentration liquid inside the molded body to be sucked out. Extraction can be performed. In addition, bubbles distributed in various parts of the extraction tank are a source of cavitation, so for many molded products,
Alternatively, the cavitation effect can be given relatively uniformly to each part of the molded body.

In the present invention, it is preferable that the solvent is stirred and fluidized when extracting the organic binder. By using the fluidization by stirring the solvent in this way, it is possible to more reliably fill the various parts in the extraction tank with fine bubbles,
The extraction effect can be further enhanced.

[0012]

Next, a specific embodiment of the method for extracting a water injection solvent from a powder injection molded article according to the present invention will be described with reference to the drawings.

(Example 1) Carbonyl iron powder (ISP S
9.5 parts of a binder comprising the following components was heated and kneaded at 150 ° C., cooled, and pulverized to 100 parts of -1641 (average particle size: 4 μm) to obtain a raw material for injection molding. <Binder> Strength component (non-extractable component): PA12 elastomer (E40S3 manufactured by Daicel) 35 parts Lubricant: N, N'-ethylenebisstearic acid amide 10 parts Extractable component: N, N'-diacetylpiperazine 55 Department

As an injection molding machine, an in-line screw molding machine having a mold clamping force of 50 tons and a screw diameter of 28 mm was used. The cylinder temperature was 150 ° C., and the injection pressure was 800 kg / c.
m ² , injection speed (screw advance speed) 20 mm / sec
In c, the molded body 1 having the cross-sectional shape shown in FIG. 1 was molded.

Next, using a water solvent extraction apparatus 2 as shown in FIG. 2, 30 pieces of the above-mentioned molded articles 1 were immersed in water, and stirred at 70 ° C. for 4 hours at the following levels 1-4. Extracted and defatted. In the water solvent extraction device 2, the water tank 3 is connected to the ultrasonic generator 4 so that ultrasonic waves are generated from the bottom surface of the water tank 3, and the bottom of the water tank 3 is provided with an air pump 5. From the air (0.
A large number of air diffusers 6 (pore diameter: 0.3 mm) for generating bubbles by ejecting ² kg / cm ² ) are arranged. A stainless steel basket 7 is supported in the water tank 3, and 30 molded bodies 1 are placed on the basket 7. Further, the water solvent in the water tank 3 is stirred by the stirring device 8. In addition, in order to prevent rust, 5% of a rust preventive (CS1000 manufactured by Otsuka Chemical Co., Ltd.) is added to the water solvent in the water tank 3. Level 1: While irradiating ultrasonic waves with 200W output,
Bubbles were ejected from the air diffuser 6. Level 2: Only bubble blowing was performed. Level 3: Only ultrasonic irradiation was performed. Level 4: Neither bubble blowing nor ultrasonic irradiation was performed.

The results are shown in Table 1. here,
The extraction rate was calculated as follows. Extraction rate: The initial weight and the weight of the work dried at 50 ° C. after the extraction are measured and calculated by the following formula. Extraction rate (%) = (initial weight−dry weight after extraction) / initial binder weight In the appearance after degreasing, those with cracks and blisters visually observed were evaluated as x, and those not observed were evaluated as ○. The “maximum extraction rate” is the value of the maximum extraction rate among the 30 pieces, and the “minimum extraction rate” is the value of the lowest extraction rate among the 30 pieces.

[0017]

[Table 1]

FIG. 3 shows that for each of the levels 1-4,
The graph which shows the dispersion | variation (ascending order) of the extraction rate in 30 molded objects is shown.

As is clear from these results, level 1
In this example, there was almost no variation due to the installation position of the molded body 1, and a constant high extraction rate was obtained. On the other hand, at levels 2 and 3, there is large variation between individuals, and the extraction rate is inferior to that at level 1. Level 4
, Both the variation and the extraction rate are further inferior to the levels 2 and 3.

Example 2 Fine powder of stainless steel (SUS430, average particle size 10 μm) produced by a water atomizing process
m) 9.4 parts of a binder consisting of the following components was heated and kneaded at 150 ° C. in 100 parts, cooled and pulverized to obtain a raw material for injection molding. <Binder> Strength component (non-extractable component): PA12 elastomer (E40S3 manufactured by Daicel Corporation) 35 parts Lubricant: N, N'-ethylenebislauric amide 10 parts Extractable component: N, N'-diacetylpiperazine 55 Department

As an injection molding machine, an in-line screw molding machine having a mold clamping force of 50 tons and a screw diameter of 28 mm was used. The cylinder temperature was 150 ° C., and the injection pressure was 800 kg / c.
m ² , injection speed (screw advance speed) 20 mm / sec
In c, the molded body 1 having the cross-sectional shape shown in FIG. 1 was molded.

Next, four molded articles 1 were immersed in water using the aqueous solvent extraction device 2 and extracted and degreased at 80 ° C. × 4 hours at the following levels 1 and 2 with stirring. Level 1: While irradiating ultrasonic waves with an output of 600 W,
Bubbles were ejected from the air diffuser 6. Level 2: Only ultrasonic irradiation was performed.

The results are shown in Table 2. The evaluation of the obtained degreased body was the same as in Example 1.

[0024]

[Table 2]

As is evident from the results, at level 1, the extraction rate was large and no abnormal appearance was observed, whereas at level 2, the molded body 1 was damaged and the extraction rate could not be measured. .

Example 3 Fine powder of stainless steel (SUS430, average particle size 10 μm) produced by a water atomizing process
m) 9.4 parts of a binder consisting of the following components was heated and kneaded at 150 ° C. in 100 parts, cooled and pulverized to obtain a raw material for injection molding. <Binder> Strength component (non-extractable component): PA12 elastomer (E40S3 manufactured by Daicel Corporation) 35 parts Lubricant: N, N'-ethylenebislauric amide 10 parts Extractable component: N, N'-diacetylpiperazine 55 Department

As an injection molding machine, an in-line screw molding machine having a mold clamping force of 50 tons and a screw diameter of 28 mm was used. The cylinder temperature was 150 ° C., and the injection pressure was 800 kg / c.
m ² , injection speed (screw advance speed) 20 mm / sec
At c, a round bar tensile test piece (zipper part φ12 mm,
(Test part φ8 mm, total length 100 mm).

Next, using the aqueous solvent extraction apparatus 2, 30 molded articles were immersed in water, and extracted and degreased at 80 ° C. for 4 hours at the following levels 1 to 4 with stirring. Level 1: While irradiating ultrasonic waves with 200W output,
Bubbles were ejected from the air diffuser 6. Level 2: Only bubble blowing was performed. Level 3: Only ultrasonic irradiation was performed. Level 4: Neither bubble blowing nor ultrasonic irradiation was performed.

The defatted body obtained was evaluated in the same manner as in Example 2. The results are shown in Table 3.

[0030]

[Table 3]

As is clear from these results, as in the case of the first embodiment, at the level 1, there is almost no variation due to the installation position of the molded body 1, and a constant high extraction rate is obtained. On the other hand, at levels 2 and 3, there is large variation between individuals, and the extraction rate is inferior to that at level 1. At level 4, both the variation and the extraction rate are level 2,
Even worse than 3.

Example 4 Fine powder of stainless steel (SUS430, average particle size 10 μm) produced by a water atomizing process
m) 10.5 parts of a binder composed of the following components was heated and kneaded at 150 ° C., cooled, and pulverized to 100 parts to obtain a raw material for injection molding. <Binder> Strength component (non-extractable component): polyethylene 34 parts Lubricant: stearic acid 11 parts Extractable component: polyethylene oxide (UCC poly)
oxWSR301) ... 55 parts

As an injection molding machine, an in-line screw molding machine having a mold clamping force of 50 tons and a screw diameter of 28 mm was used. The cylinder temperature was 125 ° C. and the injection pressure was 800 kg / c.
m ² , injection speed (screw advance speed) 20 mm / sec
At c, a round bar tensile test piece (zipper part φ12 mm,
(Test part φ8 mm, total length 100 mm).

Next, using the aqueous solvent extraction apparatus 2, the four molded articles were immersed in water, and extracted and degreased at 50 ° C. × 8 hours at the following levels 1 to 4 with stirring. Level 1: While irradiating ultrasonic waves with 200W output,
Bubbles were ejected from the air diffuser 6. Level 2: Only bubble blowing was performed. Level 3: Only ultrasonic irradiation was performed. Level 4: Neither bubble blowing nor ultrasonic irradiation was performed.

The defatted body obtained was evaluated in the same manner as in Example 2. The results are shown in Table 4.

[0036]

[Table 4]

As is apparent from the results, the levels 1 to 4
, The appearance of the molded body was almost the same, but at level 1, a high extraction rate was obtained. On the other hand, the extraction rates at levels 2, 3, and 4 are inferior to those at level 1.

From the above results, when ultrasonic irradiation is performed while jetting bubbles, not only rapid extraction becomes possible,
It can be seen that a negative pressure can be uniformly applied to a large number of molded bodies. On the other hand, in the case of only ultrasonic irradiation, there is a problem that the molded body is damaged when the irradiation output is increased. The reason is that in the case of only ultrasonic waves, the solvent partially evaporates into bubbles due to the degassing effect of the ultrasonic waves, and when the bubbles are broken, strong cavitation occurs and a large negative pressure effect is caused. For
It is considered that the combined use of the foam and the ultrasonic wave reduces the cavitation due to the elastic compression effect of the foam, and brings about a relatively small negative pressure effect on the molded body. In this way, by using bubbles and ultrasonic waves together, it is possible to generate cavitation at a level that does not damage the molded body, and the high-concentration liquid inside the molded body is sucked out by the negative pressure effect of this cavitation,
It becomes possible to perform rapid extraction by increasing the concentration gradient inside the molded body. In addition, since cavitation is caused by bubbles distributed at various locations in the extraction tank, the effect of cavitation can be given relatively uniformly for a large number of molded articles or for each part of the molded articles.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a molded body according to a first embodiment.

FIG. 2 is a configuration diagram of an aqueous solvent extraction device.

FIG. 3 is a graph illustrating a variation in an extraction rate according to the first embodiment.

[Explanation of symbols]

 Reference Signs List 1 molded body 2 water solvent extraction device 3 water tank 4 ultrasonic generator 5 air pump 6 diffuser tube 7 basket 8 stirrer

Claims (2)

[Claims] An aqueous solvent extraction method for a powder injection molded article, comprising extracting and degreasing the organic binder with water or a solvent containing water as a main component from a molded article obtained by mixing a powder and an organic binder and injection molding. A method for extracting a water-based solvent from a powder injection molded article, comprising: irradiating the molded article with the ultrasonic wave while blowing the foam so as to wrap the entire molded article in a state where the molded article is immersed in the solvent. 2. The method according to claim 1, wherein the solvent is stirred and fluidized when extracting the organic binder.