JPH09227248A - Porous sintered compact and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily produce a lightweight sintered compact having high mechanical strength, liable to the penetration of a liq. such as water and used as the material of an aeration pipe, an aromatic holding means, etc. SOLUTION: Powder formed by sticking inorg. fine particles to the surfaces of plastic particles is compacted by sintering to obtain the objective porous sintered compact. The pref. amt. of the inorg. fine particles is 0.01-40wt.% of the amt. of the plastic particles. The pref. average particle diameter of the plastic particles is 35-650μm and that of the inorg. fine particles is <=30μm. The plastic particles are preferably thermoplastic resin particles and polystyrene and/or PP particles are suitable for use as the plastic particles. Fine silica- alumina particles are suitable for use as the inorg. fine particles.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a porous sintered body and a method for producing the same, and more particularly to a porous sintered body containing plastic powder as a main component and a method for producing the same.

[0002]

2. Description of the Related Art For example, a porous tubular body made of plastic or ceramics has been conventionally used for a fish tank for appreciation and an air diffuser for sewage treatment. The porous tubular body is manufactured by compression-molding powder and sintering it.

Although a porous tubular body made of plastic powder is lightweight and easy to handle, plastic is hydrophobic and has poor wettability with water, and therefore bubbles released into water are not fine. , The oxygen absorption rate of water does not increase. In addition, even if the porous sinter of plastic is impregnated with a liquid fragrance, the fragrance is immediately released and the fragrance releasing function is lost.

On the other hand, the ceramic porous sintered body is
When used as an air diffuser material, it has the advantage that minute bubbles are generated and the oxygen absorption rate is high, but it is brittle and easily broken, and it is heavy and not easy to handle. Also, the sintering temperature has to be very high, which is costly.

[0005]

SUMMARY OF THE INVENTION In view of the above circumstances, the object of the present invention is to be lightweight, have high mechanical strength, and be easily penetrated by a liquid such as water. It is an object of the present invention to provide a porous sintered body which is highly expensive and can be impregnated with an aromatic agent for a long period of time as a material for holding an aromatic agent, and which is easy to produce, and a method for producing the same.

[0006]

The present invention relates to a porous sintered body in which a powder having a structure in which inorganic fine particles are attached to the surface of plastic particles is formed by sintering.

In the present invention, when the above-mentioned porous sintered body is manufactured, the plastic powder particles and the inorganic powder particles are agitated by a stirring means rotating at a high speed, and the plastic powder particles are heated by the high speed rotation. A step of adhering the inorganic powder fine particles to the surface of the plastic powder particles by this heating to form a mixed powder, and a step of forming the mixed powder into a predetermined shape dimension to obtain a raw formed body,
The present invention also provides a method for producing a porous sintered body, which comprises a step of heating the green compact and sintering the plastic powder particles.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the porous sintered body according to the present invention, the ratio of the inorganic fine particles to the plastic particles is
It is preferably 0.01 to 40% by weight.

In the porous sintered body according to the present invention, it is desirable that the plastic particles have an average particle diameter of 35 to 650 μm and the inorganic fine particles have an average particle diameter of 30 μm or less.

Also, in the porous sintered body according to the present invention, the plastic particles are preferably thermoplastic particles.

In the porous sintered body according to the present invention, polyethylene particles and / or polypropylene particles are preferable as the plastic particles, and silica-alumina type fine particles are preferable as the inorganic fine particles.

Instead of the above silica-alumina type fine particles, fine particles containing silica as a main component can be used.

The porous sintered body according to the present invention can be formed into a cylindrical shape and used as an air diffuser.

Further, the porous sintered body according to the present invention can be formed into a plate shape and used as an aromatic agent impregnating means.

In the method for producing a porous sintered body according to the present invention, a mold (particularly a mold) is vibrated while the mixed powder is filled into the mold for molding, and the mold is vibrated for sintering. Is preferred.

[0016]

Embodiments of the present invention will be described below.

<Example 1> In this example, the present invention is applied to an air diffuser.

High-density polyethylene powder with a particle size of 30-100 μ
m (average particle size 35 μm and particle size distribution is normal distribution),
Amphibole chlorite (mainly composed of silica and alumina) powder (Simstone: trade name of Brooks Agency) is classified to a particle size of 10 μm or less, and the classified Simstone powder particles have a particle size of 30 to 30 μm. 10 wt% for 100 μm high-density polyethylene powder (hereinafter, wt% is simply “%”
(Represented by) is added.

The high-density polyethylene powder and the shimstone powder were placed in the stirrer 1 shown in FIG. 2, and the stirring blade 2 was rotated at a rotation speed of 3000 rpm for 3 minutes to mix the above powders to obtain a mixed powder 3. The stirrer 1 is a Henschel (trade name) FM10B manufactured by Mitsui Miike Kogyo Co., Ltd., the internal volume is 9 liters, and the rotation speed of the stirring blade 2 is variable in the range of 975 to 3900 rpm. The high-speed polyethylene powder particles are heated by the high-speed rotation of the stirring blades 2, and the heat causes the fine particles of shimstone powder to adhere to the surfaces of the high-density polyethylene powder particles.
As shown in FIG. 3, the high-density polyethylene particles 4 are sprinkled with the shimstone particles 5.

FIG. 4 is a cross-sectional view of the periphery of the mold showing the procedure for molding the mixed powder 3 into the shape of an air diffuser.

The mold 7 is divided into two outer molds 8 and 9 and a core.
The outer molds 8 and 9 consist of 10 and the end of the core 10 (baseboard part).
Semicircular skirting board gripping parts 8a, 9a for gripping 10a are provided, and the skirting board part 10a of the core 10 is fixed to the skirting board gripping parts 8a, 9a, and the mold 7 is assembled by the three parties as a unit. It is like this. Outer molds 8 and 9 are for a vise (not shown)
Fixed to each other by. The lower end of the mold 7 is fitted into a recess 11a provided in the mold support 11, and the outer molds 8 and 9 and the core 10 that compose the mold 7 are fixed to each other.

A bracket 11b is provided on the mold support 11, and a vibrator 12 is attached to the bracket 11b. While the mixed powder 3 is being put in the mold 7, the vibrator 12 is driven to vibrate the mold 7 to move the mixed powder 3 into the mold 7.
Fill inside and mold. To supply the mixed powder 3 to the mold 7, it is preferable to use a funnel-shaped supply jig 13.

Next, as shown in FIG. 5, the mold 7 filled with the mixed powder 3 is loaded into the sintering machine 14 together with the mold supporting base 11,
Far-infrared heater attached to the side wall 15 and canopy 16
Heat and sinter by 17. The heating temperature is 150 ° C and the heating time is 30 minutes. Since the mixed powder 3 is heated via the mold 7, the material of the mold 7 and the mold support 11 is aluminum or brass having good heat conduction. During heating, the vibrator 12 is driven and the mixed powder 3 is vibrated.

Polyolefin powder such as polyethylene and polypropylene described in Example 2 described later causes thermal expansion by being heated while vibrating by a vibrator, and the powder particles are pressed against each other, thereby synergizing with sintering on the particle surface. Due to the effect, it is melted and fixed at the contact portion and sintered and molded, so that the compression step can be omitted when molding by the mold shown in FIG. 4, which is convenient.

When sintering is completed, the mold 7 and the mold support 11
Are taken out from the sintering apparatus 14, and these are decomposed to take out a sintered body. The core 10 is extracted from the sintered body using a knock pin (not shown).

As described above, the air diffusing tube 21 can be easily manufactured without requiring special equipment.

FIG. 6 is a sectional view of the air diffusing tube manufactured as described above. The air diffuser 21 is a cylindrical sintered body having an outer diameter D ₁ of 70 mm, an inner diameter D ₂ of 40 mm, and a length L of 500 mm.

FIG. 1 is an enlarged sectional view schematically showing the microscopic structure of the air diffusing tube 21.

As shown in FIG. 3, the mixed powder particles are granulated powder in which the shimstone fine particles 5 adhere to the surface of the high density polyethylene particles 4. Therefore, in the air diffuser 21 formed by molding and sintering the mixed powder of such particles, the high-density polyethylene particles 4 to which the shimstone fine particles 5 are adhered are fused to each other at the contact portion, and the pores 6 are formed at the non-contact portion. Has been formed.

FIG. 7 is a sectional view of a test apparatus for examining the oxygen absorption capacity of the diffuser tube for water.

Inside the water tank 21, an air diffuser 21 is provided with an air diffuser support 2
The air diffuser 21 is horizontally supported by 7 and 27, and the air supply pipe 22 is connected to the hollow portion 21a at one end of the air diffusing pipe 21, and the hollow portion 21a is closed by the lid 23 at the other end. Air diffuser 21
Is located at a depth D _P (300 mm in this example) from the water surface.

Air 24 is fed from the air supply pipe 22 into the hollow portion 21a at a supply rate of 10 liters per minute. The air 24 sent to the hollow portion 21a passes through the pores (6 in FIG. 1) of the air diffusing pipe 21 and becomes water.
It is released into the water 28 and becomes fine bubbles 24 that rise in the water 28.

The dissolved oxygen of water 28 was measured by a dissolved oxygen meter NY-560 manufactured by Mitsubishi Petrochemical Co., Ltd., and the oxygen absorption efficiency was determined. The oxygen absorption efficiency was about 6%. It was about twice that of the non-comparative example.

Comparative Example A sintered air diffuser made of high density polyethylene produced in the same manner as in Example 1 except that Simstone was not used, and the oxygen absorption efficiency was determined in the same manner as above. The oxygen absorption efficiency was about 3%.

FIG. 13 is a sectional view of a test apparatus similar to that of FIG. 7 according to this comparative example. Note that, in FIG. 13, portions common to FIG. 7 are represented by the same reference numerals. The air discharged from the air diffusing tube 71 does not immediately leave the surface of the air diffusing tube 71, grows by adhering to this surface, and has some large bubbles.
After reaching 75, it rises in 28 water. Therefore, the total surface area of the bubbles 75 is small, and the oxygen absorption efficiency is about half that of the first embodiment.

The reason why the bubbles 25 become fine in the first embodiment is considered to be as follows.

Polyethylene is hydrophobic, has a low critical surface tension and does not have good wettability with water, and a sintered body composed only of high-density polyethylene powder is difficult for water to enter pores and has a surface. The air that repels water due to its hydrophobicity and is released through the pores is retained by the water between the surface of the sintered body and the water, and accumulates and grows and grows due to continuous air release over time.

On the other hand, in the first embodiment, since the hydrophilic high-density polyethylene particles 4 have the hydrophilic shimstone fine particles 5 attached thereto, the critical surface tension becomes large and water enters the pores 6. The air flowing through the water in the pores 6 becomes fine bubbles and rises in the water 28 of the fine bubbles 25 without being accumulated on the surface of the air diffuser 21. Therefore, the total surface area of the bubbles 25 is increased, and as a result, the oxygen absorption efficiency is increased.

FIG. 8 is a graph showing the results obtained by changing the amount of addition of the fine powder of shimstone to the high-density polyethylene powder and determining the relationship between the amount of addition and the oxygen absorption efficiency.
If the addition amount of the Simstone fine powder is less than 0.01%, the oxygen absorption efficiency will suddenly decrease. From this result, it can be understood that the lower limit of the addition amount of the inorganic fine powder particles is preferably 0.01%.

Next, the mechanical strength of the air diffuser 21 will be described.

As shown in FIG. 9, the air diffuser 21 is placed horizontally on the surface plate 30, and the anti-rotation piece 31 prevents the air diffuser 21 from rolling. Then, the weight 29 is placed on the air diffuser 21, and the load G is applied to the air diffuser 21. The weight 29 is sequentially changed from one having a smaller weight to one having a larger weight, and the load G is gradually increased. The load G immediately before the crack 29 is generated on the surface of the air diffuser 21 is represented as the strength (kg) of the air diffuser 21.

FIG. 10 is a graph showing the results of varying the amount of addition of the fine powder of shimstone to the high-density polyethylene powder and determining the relationship between the amount of addition and the strength of the air diffusing tube.
The strength of the air diffuser according to this example is 400 kg. Although the decrease in strength is slight up to 40% of the Simstone fine powder addition,
If the above-mentioned addition amount exceeds 40%, the decrease in strength becomes sharp.
From FIG. 10, the upper limit of the addition amount of the inorganic fine powder particles is 40
It can be understood that it is good to set%.

<Embodiment 2> This example is also an example in which the present invention is applied to an air diffuser.

In this example, polypropylene powder is used instead of the high-density polyethylene powder used in Example 1. Polypropylene powder has a particle size of 700-2000 μm
(Average particle size 650 μm). The inorganic fine powder used was vitreous and pumice-like silica sand (Simlite: a product name of Brooks Agency).
It is classified to a particle size of 25 μm or less. 15% of fine powder of Simlite was added to polypropylene powder, and the sintering time was 40 minutes.

The dimensions of the air diffuser are such that the outer diameter D ₁ is 70 mm,
The inner diameter D ₂ is 55 mm and the length L is 500 mm. Others are the same as in the first embodiment. In addition, in FIG. 1, FIG. 3, FIG. 6 and FIG.
The sign with "0" added is also shown in parentheses. However, 34 is polypropylene particles, and 35 is shimlite particles.

With respect to the air diffuser 51 according to this example, the oxygen absorption efficiency and mechanical strength similar to those in Example 1 were measured. As a result, the oxygen absorption efficiency was about 6% (about 6% in the comparative air diffuser made by using only polypropylene powder without adding Simlite fine particles) and the mechanical strength was about 400 kg. The same as in Example 1 above.

In both the first and second embodiments, the oxygen absorption efficiency is high and the main component is plastic, so that it is lightweight and easy to handle, and is suitable for use in an aquarium of a fish for appreciation and a sewage treatment device. Also, use polyolefin such as polyethylene or polypropylene for the plastic powder,
%, The air diffuser tube with added inorganic fine particles,
Its burning calories are approximately 5000 kCal, which is close to that of wood, and no toxic gas is generated during burning. Therefore, it can be easily incinerated and treated as industrial waste.

Example 3 A flat plate-shaped porous sintered body was produced from the same mixed powder as in Example 1. FIG.
As shown in (a), 1 is formed on the main surface of the flat plate-shaped porous sintered body 61.
When cc of soy sauce 62 was dropped and left in a high-humidity room for 7 days and then observed, no mold was observed as shown in FIG. 6 (b). On the other hand, in the porous sintered body produced only from the polyethylene powder without adding the Simstone fine particles, a mold 72 indicated by a virtual line was generated at the soy sauce dropping position as shown in FIG. 6B. .

Simstone has antibacterial properties and prevents the growth of mold. Therefore, the flat plate (for example, disc) 61 according to this example is suitable for application to a coaster. That is, the flat plate 61 is lightweight, and even if a drink or the like in a cup (not shown) goes around the back surface of the bottom of the cup and wets the coaster, no mold is generated and it becomes unsanitary. Absent. Once mold has developed, it is difficult to completely remove it, and even a small amount of mold cannot avoid the feeling of filth.

Further, since the shimstone has antibacterial properties, the air diffusing tube according to the above-mentioned embodiment 1 to which the simustone fine particles are added is also effective for preventing fish diseases when used in the aquarium for ornamental fish. It is even more effective for water purification. It has been confirmed that the same effect can be obtained when the Simlite fine powder is used instead of the Simstone fine powder.

Example 4 A low-density polyethylene powder having a particle size of 100 to 200 μm (average particle size 150 μm) was used, and the particle size was 30.
0.5% of porous Simstone powder classified to not more than μm was added, and the mixture was stirred for 3 minutes using Henschel to obtain a mixed powder composed of particles having the same structure as shown in FIG. This mixed powder was treated in the same manner as in Example 1 above using a mold,
As shown in FIG. 12, a disk-shaped porous sintered body 66 (having the same structure as in FIG. 1) having a diameter d of 100 mm and a thickness t of 5 mm was obtained.

A disk-shaped porous sintered body 66 was impregnated with a liquid fragrance (manufactured by Kobayashi Pharmaceutical Co., Ltd., trade name Sawaletin: emits a scent of lemon lime), and allowed to stand in a room at 25 ° C. for 30 days before being disk-shaped. The scent of the porous sintered body was confirmed with the nose. as a result,
The same mild fragrance as immediately after impregnation was recognized.

From the above results, the porous sintered body according to this example can hold the fragrance as a means for holding the fragrance for a long period of time, and is effective for canceling this odor in a toilet or other places where the odor is emitted. Effective to use. This effect is exhibited by the wettability improved by the shimstone fine particles so that the liquid fragrance can easily enter the pores of the sintered body, and the fragrance can be retained. In addition, the fact that the Simstone itself is porous also makes the above effect more remarkable.

For comparison, without using the Simstone fine particles,
A disk-shaped porous sintered body was produced in the same manner as in Example 4 except that it was composed of only low-density polyethylene powder. Liquid fragrance Sawaletuin was impregnated into this comparative sintered body under reduced pressure and allowed to stand at 25 ° C. for 30 days. I was not able to admit.

Although the embodiments of the present invention have been described above, various modifications can be made to the above embodiments based on the technical idea of the present invention.

For example, as the inorganic fine particles, both of the above-mentioned shimstone and shimlite can be used in combination, and besides these, shirasu and other appropriate inorganic fine particles can be used.

As the plastic particles, polyethylene, polypropylene, or any other suitable particles may be used, and thermosetting plastic particles can also be used.
However, in this case, since the thermosetting plastic has a small volume shrinkage during sintering, it is preferable to provide the mold with a sufficient draft in order to facilitate the removal from the molding die.

Further, the porous sintered body according to the present invention can be used not only as an air diffuser but also as an ordinary filter. Furthermore, a small amount of bentonite can be used as the inorganic fine particles, and the swelling property of bentonite can be used to control the amount of water or aqueous solution permeated according to the amount of addition.

[0059]

In the porous sintered body according to the present invention, the powder having a structure in which the inorganic fine particles are adhered to the surface of the plastic particles is formed by sintering. A liquid such as water or an aqueous solution easily invades, and these functions can be sufficiently fulfilled as an air diffuser, a filter, and a fragrance holding means. Moreover, since the plastic is sintered, it is lightweight, easy to handle, and has sufficient mechanical strength.

In the production thereof, the plastic powder particles and the inorganic powder fine particles are stirred by a stirring means rotating at high speed, and the high speed rotation causes the inorganic fine particles to adhere to the surface of the plastic particles to form a mixed powder. Since it is sinter-molded, it can be sintered at a low temperature as in plastic sinter-molding, and it does not require a special device and is easy to manufacture.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view schematically showing the structure of an air diffusing tube according to an embodiment of the present invention.

FIG. 2 is a schematic sectional view of the high speed agitator.

FIG. 3 is an enlarged cross-sectional view schematically showing particles forming the air diffusing tube.

FIG. 4 is a sectional view of the mold.

FIG. 5 is a schematic cross-sectional view of a sintering device accommodating the mold.

FIG. 6 is a sectional view of the air diffuser.

FIG. 7 is a cross-sectional view of the water tank showing a usage state of the air diffuser.

FIG. 8 is a graph showing the relationship between the amount of inorganic fine particles added and the oxygen absorption efficiency.

FIG. 9 is a cross-sectional view showing a procedure for measuring the mechanical strength of the air diffuser.

FIG. 10 is a graph showing the relationship between the addition amount of the same inorganic fine particles and the mechanical strength of the air diffusing tube.

FIG. 11 shows a coaster according to an embodiment of the present invention, FIG. 11A is a perspective view showing a state in which soy sauce is dropped on the main surface, and FIG. 11B is left in a high humidity atmosphere for 7 days after dropping soy sauce. It is a perspective view of a state.

FIG. 12 is a front view of a fragrance holding disc according to an embodiment of the present invention.

FIG. 13 is a cross-sectional view of a water tank showing a usage state of an air diffuser according to a comparative example.

[Explanation of symbols]

 1 ... High-speed stirrer (Henschel) 2 ... Stirring blade 3 ... Mixed powder 4 ... Polyethylene particles 5 ... Simstone fine particles 6,36 ... Porosity 7 ... Mold 8,9 ...・ ・ Outer mold 10 ・ ・ ・ Core 11 ・ ・ ・ Mold support 12 ・ ・ ・ Vibrator 14 ・ ・ ・ Sintering device 17 ・ ・ ・ Far infrared heater 21, 51 ・ ・ ・ Air diffuser 22 ・ ・ ・ Air pipe 23 ... Lid 24 ... Air 25 ... Bubbles 26 ... Water tank 28 ... Water 29 ... Cracks 32 ... Weights 34 ... Polypropylene particles 35 ... Simlite fine particles 61・ ・ ・ Coaster 62 ・ ・ ・ Soy sauce 66 ・ ・ ・ Aromatic disc 72 ・ ・ ・ Mold

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[Procedure amendment]

[Submission date] April 19, 1996

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0046

[Correction method] Change

[Correction contents]

With respect to the air diffuser 51 according to this example, the oxygen absorption efficiency and mechanical strength similar to those in Example 1 were measured. As a result, the oxygen absorption efficiency was about 6% (about 3 % in the comparative air diffuser made only of polypropylene powder without adding the Simlite particles), and the mechanical strength was about 400 kg. The same as in Example 1 above.

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location C08L 23/06 LBZ C08L 23/06 LBZ 23/12 LBZ 23/12 LBZ 101/00 LTB 101/00 LTB (72 ) Inventor Wataru Sasaki 38-13 Takakura-cho, Hachioji-shi, Tokyo Inside Spacey Chemical Co., Ltd. ) Inventor Masao Akita 1-18-11 Uchikanda, Chiyoda-ku, Tokyo Tokyo Royal Plaza 1103 Techno Uni Stock Company In-house

Claims (10)

[Claims] 1. A porous sintered body, which is formed by sintering powder having a structure in which fine inorganic particles adhere to the surface of plastic particles. 2. The porous sintered body according to claim 1, wherein the ratio of the inorganic fine particles to the plastic particles is 0.01 to 40% by weight. 3. The plastic particles have an average particle size of 35 to 650.
The porous sintered body according to claim 1 or 2, wherein the average particle diameter of the inorganic fine particles is 30 µm or less. 4. The porous sintered body according to claim 1, wherein the plastic particles are thermoplastic particles. 5. The porous sintered body according to any one of claims 1 to 4, wherein the plastic particles are polyethylene particles and / or polypropylene particles, and the inorganic fine particles are silica-alumina fine particles. 6. The porous sintered body according to claim 1, wherein the plastic particles are polyethylene particles and / or polypropylene particles, and the inorganic fine particles are fine particles containing silica as a main component. 7. The porous sintered body according to claim 1, which has a cylindrical shape. 8. The porous sintered body according to claim 1, which has a plate shape. 9. When manufacturing the porous sintered body according to any one of claims 1 to 8, the plastic powder particles and the inorganic powder particles are agitated by an agitating device that rotates at a high speed to rotate the high speed. By heating the plastic powder particles by the above, and by adhering the inorganic powder fine particles to the surface of the plastic powder particles by this heating to form a mixed powder, and forming the mixed powder into a predetermined shape and a raw molded body. And a step of heating the green compact to sinter the plastic powder particles, a method for producing a porous sintered compact. 10. The method for producing a porous sintered body according to claim 9, wherein the mold is filled with mixed powder while vibrating the mold to perform molding, and the mold is sintered while vibrating the mold.