JP2000107596A - Production of inorganic substance molded object - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a molded object having a pellet size from a powdery inorg. substance changed in its chemical compsn. by water absorption advantageously from an aspect of a process and cost so as to keep the water absorbing capacity (reactivity with water) thereof equal to that of a powdery or granular object to provide strength not collapsed even if water absorbing capacity is exhausted to the molded object. SOLUTION: A powdery inorg. substance (A) changed in its chemical compsn. by water absorption as an essential component, a powdery hot-melt polymer (B) as an essential component and a powdery extender (C) as an arbitrary component are mixed and compressed to be shaped into a predetermined shape and the shaped object is heated under a temp. condition melting the hot-melt polymer (B) to be cooled and molded. The representative example of the inorg. substance (A) is alkaline earth metal oxide (especially, BaO) and that of the hot-melt polymer (B) is polyolefin and that of the extender is an inorg. or carbonaceous porous material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a molded article of an inorganic substance having a necessary strength, and more particularly, to a method of producing a molded article of an inorganic substance whose chemical composition changes by absorbing water.

[0002]

2. Description of the Related Art Among inorganic substances, there is an inorganic substance which has a water absorbing action and changes its chemical composition by itself. For example, barium oxide (BaO) or calcium oxide (Ca
O) absorbs water and changes to hydroxide.

[0003] By taking advantage of such a water-absorbing action, BaO and CaO can be used as a water-absorbing agent for selectively adsorbing and removing a trace amount of water in a gas. For example, Japanese Unexamined Patent Application Publication No. Hei 9-142833 filed by the present applicant discloses that ammonia containing a trace amount of water is mixed with BaO alone or a mixture mainly containing BaO (for example, a mixture with CaO) under substantially room temperature conditions. 3) shows a method for removing moisture in ammonia which is brought into contact with the ammonia.

In the method using BaO (or BaO and CaO), only water is adsorbed and removed at room temperature. Therefore, the method of adsorbing and removing water using molecular sieves (co-adsorption of ammonia and increase in space velocity, the water removal rate ), Which is advantageous from a practical point of view as compared with a water removal method using a getter alloy made of Zr-V-Fe (see Japanese Patent Application Laid-Open No. 4-292413, which requires heating at about 100 ° C.). it is conceivable that.

[0005]

SUMMARY OF THE INVENTION The above-mentioned Japanese Patent Application Laid-Open No. 9-142.
No. 833, BaO (or BaO and Ca
It is stated that the adsorbent composed of O) can be packed in a column in the form of powder, granules, or molded products. In the examples, examples are given in which the column is packed and used in the form of powder or granules. However, when packing the adsorbent into a large column or tower, it is more practical to shape it into, for example, pellets, because it is easier to handle and the pressure drop during the filling operation is smaller. .

However, when the pellet-shaped shaped material of BaO or CaO adsorbs moisture, it itself forms Ba (OH).
_2. Where the chemical composition changes as Ca (OH) ₂ , volumetric expansion occurs in response to the change in the chemical composition, so that the strength of the excipient decreases, eventually disintegrating and pulverizing. I cannot escape. When the extrudate collapses, the pressure loss increases and it becomes impossible to pass the gas to be treated such as ammonia stably, so that the adsorbent must be replaced without exhausting its original water absorption capacity. This is disadvantageous both economically and man-hourly.

[0007] Under such a background, the present invention is to produce a pellet-sized molded product from a powdered inorganic substance whose chemical composition changes due to water absorption in a process and cost-effective manner. Water absorption capacity (reactivity with water)
The purpose of the present invention is to maintain the same strength as a powdery or granular material and to have a strength that does not collapse even when its water absorbing capacity is exhausted.

[0008]

The process for producing an inorganic material molded product according to the present invention comprises a powdery inorganic material (A) whose chemical composition changes due to water absorption as an essential component, and a powdery inorganic material as an essential component. The heat-fusible polymer (B) and a powdery filler (C) as an optional component are mixed, compressed and shaped into a predetermined shape. (B) is heated under a temperature condition at which it melts, and then cooled and molded.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

In the present invention, a powdery inorganic substance (A) and a powdery heat-fusible polymer (B) are used as raw materials. Also preferably, a powdery filler is used together with these.
(C) can be used.

Here, as the inorganic substance (A), an inorganic substance whose chemical composition changes due to water absorption is used. Examples of such inorganic substances are oxides of alkaline earth metals such as Ca, Sr and Ba, of which BaO and then CaO are important. Two or more inorganic substances (A) can be used in combination.

Examples of the heat-fusible polymer (B) include polyolefins such as homopolymers and copolymers of ethylene and homopolymers and copolymers of propylene. In addition, polyvinyl chloride, polyvinylidene chloride, poly (meth) Acrylate, poly (meth) acrylonitrile, polyamide, polystyrene, polyester,
Various thermoplastic resins such as polyvinyl acetate, polyvinyl formal, polyvinyl acetoacetal, and polybiporbutyral can be used. Among these, flexibility (elongation property), melting point (not excessively high and not melting or softening at the use temperature of the target molded product), resin cost, specific gravity (affecting uniform mixing properties), inorganic substances (A ) (Or polyolefin, especially polyethylene, especially high-density polyethylene) is important in consideration of the adhesiveness between (or this and the filler (C)). Hot melt polymer
(B) may be used in combination of two or more.

As the filler (C), an inorganic or carbonaceous porous material is preferably used. Examples of the inorganic porous material include activated alumina, silica gel, zeolite (such as molecular sieves), bentonite, clay (clay), diatomaceous earth, and diatomaceous earth in which a metal component or graphite is supported. An example of the carbonaceous porous material is activated carbon. In addition, fused alumina (α-alumina) or the like can be used as the filler (C). The extender (C) may be used in combination of two or more kinds.

The extender (C) is an optional component used as necessary, but it is preferable to use it in combination. This is because uniform mixing of the inorganic substance (A) and the hot-melt polymer (B) is not always easy due to the difference in specific gravity.
When (C) is used together, the dispersibility of each component during mixing is improved,
Further, the porosity can be ensured by the filler (C).
Furthermore, by mixing the filler (C), the inorganic substance (A)
Is diluted, so that expansion of a molded product such as a pellet can be reduced. Even if the filler (C) has porosity, it does not significantly affect the amount of water adsorbed or the speed of adsorbing water, and plays only a sub-role from such a viewpoint.

The above-mentioned inorganic substance (A), a hot-melt polymer
Both (B) and the extender (C) are used in a powder form for mixing. The particle size of the powder is determined in consideration of the availability of raw materials, the ease of uniform mixing, and the tightness of bonding of the heat-fusible polymer (B) after heating and melting. ) Is 100 mesh (147 μm) or less, especially 150 mesh (104 μm) or less, and it is better to be as fine as possible. The filler (C) is 24 mesh (701 μm).
It is preferable that the mesh size is as small as possible, especially 32 mesh (495 μm) or less. However, the particle size range is not necessarily limited to this range.

The mixing ratio of the powdery inorganic substance (A), the powdery heat-fusible polymer (B) and the extender (C) is as follows:
When the total amount of (B) and (C) is 100% by weight,
Suitably, the proportion of (A) + (C) is 90 to 60% by weight, the proportion of (A) is 20% by weight or more, and the proportion of (B) is 10 to 40% by weight. In the case of the two-component system (A) and (B),
The proportion of (A) is 90 to 60% by weight (preferably 85 to 65%).
% By weight), and the proportion of (B) is 10 to 40% by weight (preferably 15 to 35% by weight). When the proportion of (B) is too large, the water absorption capacity becomes insufficient, and when the proportion of (B) is too small, the strength as a molded product becomes insufficient.

In the case of the three-component system (A), (B) and (C), the proportion of (A) is 70 to 20% by weight (particularly 6%).
5 to 25% by weight), and the proportion of (B) is 10 to 40% by weight.
It is particularly preferred that the proportion of (C) is 5 to 65% by weight (especially 10 to 60% by weight). This is because in this range, the balance of the uniformity, the water absorbing ability, the strength of the molded product, and the like at the time of mixing the powder can be obtained.

The mixing of the powdery inorganic substance (A) and the powdery heat-fusible polymer (B) (and the powdery filler (C)) is carried out by using a horizontal cylindrical mixer, a double cone. Container-type mixers such as mold mixers, ribbon-type mixers, single-shaft lot-type mixers, high-speed flow-type mixers, rotating disk-type mixers, air-flow agitator mixers, conical screw mixers, etc. This is performed using a mixing device such as a container-fixed type mixing device.

After the powder is mixed, it is compressed and shaped into a predetermined shape. Compression can be performed using a device such as a single-shot tableting machine or a rotary tableting machine.

The shape of the excipient can be, for example, a sphere or an ellipsoid, a pellet (short column), a disk, a stone, a die, a donut, and the like. The size of the shaped object is not limited. For example, in the case of a pellet, the diameter is about 3 to 8 mm and the length is 3 to 10 mm.
It is often about mm.

After obtaining the shaped article, the shaped article is heated under the temperature conditions at which the hot-melt polymer (B) is melted, and then cooled and molded. The cooling may be either standing cooling or forced cooling. Thereby, a desired inorganic substance molded product is obtained.

<Use> The inorganic substance molded product obtained by the above method is particularly useful as a method for removing a trace amount of water contained in the gas to be treated. At this time, the column or tower may be filled with the above-mentioned inorganic substance molded product, and the gas to be treated may be passed.

<Function> The inorganic material molded article of the present invention is filled
Gas containing a small amount of water passes through the column or tower
Causes moisture to be absorbed by the inorganic substance (A) in the inorganic substance molded product.
The moisture content in the passing gas is significantly reduced. So
Water absorbed by the inorganic substance (A)
(A) The chemical composition itself changes. For example, inorganic substances
Taking the case where (A) is BaO as an example, BaO + H_TwoO → Ba (OH)_Two  Ba (OH)_Two Is generated. Therefore moisture
May be physically adsorbed on the inorganic material molded product.
Yes, but most of the time is spent on the above reaction,
The mechanism of contact with the natural gas is more
Reaction of inorganic substance (A) in inorganic substance molded product with water
Is accurate. Note that the true density is 5.7g /
cm^Three From 4.5g / cm^Three , Causing volume expansion.

Since the inorganic material molded product obtained by the method of the present invention is bonded to the heat-fusible polymer (B) so as to be capable of slightly elongating, the inorganic material (A) contained therein is The chemical composition changes (for example, BaO becomes Ba
(Change to (OH) ₂ ), the molded product shape is maintained even when volume expansion occurs, and the inorganic substance (A) has such a strength that it does not collapse even when the water absorbing capacity is exhausted. In addition, since the strength of the molded product is maintained, troubles such as clogging due to destruction of the molded product do not occur during the filling of the column or the tower and the process of processing the gas to be treated.

[0025]

The present invention will be further described with reference to the following examples.

Examples 1 to 7 and Comparative Examples 1 and 2 <Preparation of Raw Materials> As a powdery inorganic substance (A) whose chemical composition changes due to water absorption, BaO having a particle size of 2 to 108 μm is used.
Powder was prepared.

A high-density polyethylene powder having a particle size of 10 to 80 μm and a melting point of about 132 ° C. was prepared as the powdery heat-fusible polymer (B).

The following were prepared as the powdery filler (C). (C ₁ ): molecular sieve (MS-13X) powder having a particle size of 60 to 80 mesh (C ₂ ): activated alumina powder having a particle size of 60 to 80 mesh (C ₃ ): diatomaceous earth powder having a particle size of 60 to 80 mesh

<Manufacture of molded article> The above powdery inorganic substance
(A), powdery heat-fusible polymer (B), powdery filler
The three components (C) were mixed at a predetermined ratio by a horizontal cylindrical mixer, and then compressed by a rotary tableting machine to form cylindrical pellets. Then, the pellet-shaped shaped product was placed in a column oven set at a temperature of 140 ° C.
After heating for minutes, the mixture was allowed to cool to obtain a molded product.

<Moisture Load Test> The molded product thus obtained was subjected to a temperature of 22 ° C. and a humidity of 85% RH (75 to 90% RH).
However, in most cases, it was left in a high-humidity atmosphere of 85% RH) for a predetermined period of time to carry out moisture load, and the strength of the molded product after the load time passed was measured (the pellet was placed on a table in a vertical position). The pellets were placed on top of each other, pressure was applied from above to measure the load when the pellets were broken), and it was observed whether the shape was maintained (whether the powder was spontaneously powdered).
Table 1 shows the conditions and results. In the place of C in the column of mixing ratio
C _1, C _2, C ₃ phrase is a bulking material used (C).

[0031]

[Table 1]  Mixing ratio (wt%) Moisture load of excipientMolded product after moisture load test  ABC Heating temperature Time Strength Expansion rate Natural powdering amount  Example 1 40 20 40C₁ 140 ° C 431hr 4.35 15% No powdering Example 2 50 30 20C₁ 140 ° C 387hr 4.94 5% No powdering Example 3 30 20 50C_Two 140 ℃ 378hr 5.34 9% No powdering Example 4 50 30 20C_Two 140 ° C 379hr 4.57 15% No powdering Example 5 40 20 40C_Three 140 ℃ 378hr 3.21 19% Micro powderization Example 6 50 30 20C_Three 140 ℃ 407hr 4.87 18%Example 7 70 30-140 ° C 380hr 5.46 28% No powdering  Comparative Example 1 10 30 60C₁ -32hr 1.78^* ** Many fine powders^# Comparative Example 2 10 30 60C ₁ 130 ° C 32hr 2.25 ^{* **} Lots of fine powder ^#  (Note) The size of the pellet is φ5.0mm × (6.0-8.3) mm, and the weight is 0.20 ~ 0.31g. The unit of strength is kg / mm^Two.^* Is the value before the load test (the strength after the load test cannot be measured due to pulverization).^**Cannot be measured due to pulverization.^# Is pulverized as efflorescence.

As shown in Table 1, in Examples 1 to 7,
It can be seen that the strength of the molded product is still high after 378 to 431 hours, and the amount of spontaneous pulverization is zero or very small. On the other hand, Comparative Example 1 in which the excipient was not heat-treated
In Comparative Example 2 where the heat treatment temperature did not reach the melting temperature of the high-density polyethylene, the pulverization proceeded in such a way that the powder was pulverized in a short time moisture load test. I'm advancing.

<Water absorption capacity test> The molded products of Examples 1 to 7 and Comparative Examples 1 and 2 were packed in a SUS column so as to be 19.5 g in terms of BaO, and ammonia having a water concentration of 27 ppm was passed therethrough. . The condition is that the ammonia flow rate is 1600
ml / min, SV was set at 2250 hr ^-1 , LV was set at 12.5 cm / sec, and the temperature was set at room temperature. As Reference Example 1, the particle size is 2 to 108 μm.
An experiment was also conducted when the column was filled with m 2 BaO powder to a concentration of 0.052 g. However, in Reference Example 1, the conditions were changed. Table 2 shows the conditions and results.

[0034]

[Table 2]  Examples 1 to 7 Comparative Examples 1 and 2 Reference Example 1  Conditions Column inner diameter 16.5 mm 16.5 mm 4.3 mm Packing length 200 mm 200 mm 2 mm Packing amount (BaO equivalent) 19.5 g 19.5 g 0.052 g Moisture concentration 27 ppm 27 ppm 2 ppm Ammonia flow rate 1600 ml / min 1600 ml / min 60 ml / min SV 2250 hr^-1 2250 hr^-1 120000 hr^-1 LV 12.5 cm / sec 12.5 cm / sec 6.73 cm / secTemperature Room temperature Room temperature Room temperature  Outlet moisture concentration After 50 hr <5 ppb <5 ppb <5 ppb After 100 hr <5 ppb <5 ppb-200 hr After <5 ppb <5 ppb-200 hr After water removal Good Good Good Mold breakage NoneFlow rate fluctuation None Flow rate decrease −

As can be seen from Table 2, Examples 1 to 7
In, the gas to be treated could be supplied stably through the treatment for 200 hours, and the water could be removed smoothly. In Comparative Examples 1 and 2, pulverization was observed with the passage of time, and although water was removed, the flow rate was reduced due to pressure loss, and there was a possibility that the stable supply of the gas to be treated was hindered. Comparing Examples 1 to 7 with Reference Example 1, it can be seen that in Examples 1 to 7, the water-absorbing ability did not decrease despite the fact that the molded product was formed by the hot-melt polymer (B). Understand.

[0036]

According to the present invention, the following excellent effects can be obtained. (A) A pellet-sized molded product can be produced advantageously in terms of process and cost. (B) Since the inorganic material molded product obtained by the method of the present invention is bonded to the heat-fusible polymer (B) so as to be slightly stretchable, the inorganic material (A) contained therein is
(For example, BaO becomes Ba (OH)
(Change to ₂ ), the shape of the molded product is maintained even when volume expansion occurs, and the inorganic substance (A) has such strength that it does not collapse even when the water absorbing capacity is exhausted. (C) Since the strength of the molded product is maintained, troubles such as clogging due to destruction of the molded product do not occur at the time of filling the column or tower and during the process of processing the gas to be treated. (D) Water absorption capacity of the molded product (reactivity with water)
Is as good as powdery or granular ones.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4G066 AA04B AA16B AA20B AA61B AA61C AA70B AA70C AC13B AE11B BA20 BA22 BA35 BA36 BA38 CA29 CA43 DA05 FA20 FA21 FA27 FA37 4G076 AA02 AA24 AA26 AC06 BA42 BC08 BD02 CA11

Claims (6)

[Claims] A powdery inorganic substance (A) whose chemical composition is changed by water absorption as an essential component, a powdery heat-fusible polymer (B) as an essential component, and a powdery as an optional component Is mixed with the filler (C) in a shape, compressed and shaped into a predetermined shape, and the shaped material is heated under a temperature condition at which the hot-melt polymer (B) melts, and then cooled. A method for producing an inorganic substance molded product, comprising: 2. When the total amount of (A), (B) and (C) is 100% by weight, the proportion of (A) + (C) is 90 to 60% by weight.
And the proportion of (A) is 20% by weight or more and the proportion of (B) is 10% by weight.
The method according to claim 1, wherein the amount is from 40 to 40% by weight. 3. When the total amount of (A), (B) and (C) is 100% by weight, the proportion of (A) is 70 to 20% by weight,
The proportion of (B) is 10 to 40% by weight, and the proportion of (C) is 5 to 6%.
3. The method according to claim 2, wherein the amount is 5% by weight. 4. The method according to claim 1, wherein the inorganic substance (A) is an alkaline earth metal oxide. 5. The method according to claim 1, wherein the heat-fusible polymer (B) is a polyolefin. 6. The method according to claim 1, wherein the extender (C) is an inorganic or carbonaceous porous material.