JP3386459B2 - Water-resistant sepiolite molded article and method for producing the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a sepiolite molded article having excellent water resistance that does not deflocculate even when immersed in water, and is resistant to heat shock, and a method for producing the same.

[Prior art]

Sepiolite is a highly flexible mineral that is classified as chain-structured clay with tunnels running along the fiber axis and has adsorptivity like zeolite, and is dispersed in water like bentonite. It is a unique mineral that has suspending properties, has a denaturing property and plasticity, and also has a dry solidification property that hardens when kneaded and dried with water like kaolinite and a sinterability that hardens when fired. is there.

An attempt to produce a porous molded article from this sepiolite as a raw material has been proposed in Japanese Patent Publication No. 55-31085.

The technique disclosed in Japanese Patent Publication No. 55-31085 is as follows: "In a method of forming a porous body using sepiolite as a raw material, (a) a step of crushing sepiolite and then adding water to adjust the humidity; A step of sufficiently kneading a wet material; and (c) a step of molding and firing the kneaded material; a method for producing a sepiolite molded article, which comprises the above steps. " The detailed description discloses an example in which the firing temperature is 300 ° C. to 500 ° C. In Example 3, when the aluminum metal ratio is 3.0% and the firing temperature is 800 ° C., the pore volume is slightly small. It is shown that it was revealed that the specific surface area was large, but the breaking strength was remarkably large although it was small.

However, firing at a temperature of 300 ° C to 5 ° C as described above.
When the test piece was made at a temperature of 00 ° C, it was deflocculated when immersed in water, and there was a problem with water resistance. Also sepiolite alone
When fired at a temperature of 800 ° C or higher, it was transformed into steatite, increasing brittleness and decreasing strength.

[Problems to be Solved by the Present Invention]

As described above, the conventional sepiolite molded article having a low firing temperature has a drawback that it is deflocculated when immersed in water and its strength is lowered.

Therefore, an object of the present invention is to provide a strong sepiolite molded article having high water resistance and not cracked by heat shock even when it is rapidly heated or cooled.

[Means and Actions for Solving Problems]

As a result of intensive studies conducted by the present inventors in line with the above object, a sepiolite molded body that does not deflocculate even when immersed in water and does not crack due to heat shock even when rapidly heated or rapidly cooled has a firing temperature range of about 650. It was found that it can be produced by adjusting the temperature in the range of ℃ to 800 ℃.

That is, the water-resistant sepiolite molded product of the present invention is obtained by crushing a sepiolite raw material, adding water to this, and kneading without mixing (in other words, mastication) to obtain a conditioned sepiolite powder. The sepiolite powder is pressure-molded and then obtained by firing, and more specifically, the water-resistant sepiolite molded article of the present invention is obtained by crushing a sepiolite raw material into 100 mesh or less, and adding water thereto. Then, the mixture is stirred and mixed without kneading to obtain a humidity-controlled sepiolite powder having a water content of 40 to 200 wt.%. The humidity-controlled sepiolite powder is pressure-molded and then fired in a temperature range of about 650 to 800 ° C. The obtained product has a major feature that the pore volume of the pore size of 1000 Å or more is 0.15 cc / g or more, and it can swell or peptize even when immersed in water. Not against water It has a glue and has a high freezing and non-destructive strength that does not break or damage even if it is rapidly cooled by freezing it in water, and it is brittle even if it is immersed in cold water when heated to a high temperature of 600 ° C. It has high heat resistance and heat shock resistance that does not cause damage or damage.

A preferred method for producing the water resistant sepiolite molded article of the present invention is illustrated below.

Sepiolite is crushed to 100 mesh or less, preferably 150 mesh or less, water is added to the sepiolite powder, and the water content of the hydrolyzed sepiolite powder is adjusted to 40 to 200 wt.%, Preferably 45 to 55 wt.%. . When stirring the water-mixed sepiolite powder with stirring to uniformly control the humidity, the most important thing to note is that no kneading is performed. In the technique disclosed in JP-B-55-31085, it is important to sufficiently knead, but in the present invention sepiolite having the unique physical properties of the present invention is that kneading is not performed before molding. It is important to obtain a molded body.

The humidity-controlled sepiolite powder is formed into an arbitrary shape, for example, pressure-molded, and after the molded body is dried at a temperature of 100 ° C to 150 ° C, the temperature is about 650 ° C to 800 ° C, preferably 700 ° C to 800 ° C, particularly It is preferably fired at 720 ° C to 770 ° C to obtain a sepiolite molded product.

The obtained sepiolite molded product has the following physical properties.

Specific surface area: 120 to 180 m ² / g (BET method) Pore volume: 0.6 to 1.0 cc / g (30,000 PSIA or less mercury intrusion method) Pore volume distribution: 200 Å or less 0.30 cc / g or less (30,000 PSIA 200 to 600 Å or less) About 0.35 cc / g or less or less mercury porosimetry) 600~1000Å 0.10cc / g or less 1000Å or 0.15 cc / g at a pressure of more than 50 kg / cm ² to sepiolite plate-like body of 54 mm × 18 mm × 6 mm obtained by press molding, Bend strength at 45 mm intervals: 0.8 kg to 2.0 kg Bending strength was measured using the device shown in FIG. That is, a support piece 12 having a radius of curvature of 5 mm at the tip at 45 mm intervals is provided on the substrate 11, a test piece 14 is placed on the support piece 12, and a load is applied by a holding plate 13 having the same radius of curvature as the tip of the support piece. The bending strength was defined as the load (kg) at the time of breaking the test piece 14.

When a peptization test was conducted by immersing the sepiolite molded article in water to swell and peptize, the water-resistant sepiolite of the present invention did not swell and peptize.

When the test piece was heated to 600 ° C. and then rapidly cooled and frozen in order to test the freezing non-destructive strength property, the water-resistant sepiolite of the present invention did not become brittle and did not break and damage.

Furthermore, in order to test the thermal shock resistance, the test piece was
After heating at 350 ° C for 30 minutes and letting it cool at room temperature for 30 minutes, a fixed amount of water was added as one cycle, and a 3000-cycle heat shock test was repeated. The bending strength of the test piece was 2 / the initial strength. Showed 3 or more.

〔Example〕

  Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1 Water content 17% by weight. High-purity sepiolite from Turkey (more than 92% of sepiolite purity) was crushed to 200 mesh with a crusher and mixed well with a mortar mixer.

Water is added at a ratio of 6 kg of water to 10 kg of crushed sepiolite, and well stirred and mixed by hand so as not to knead in a container to uniformly control the humidity. 100 more humidified sepiolite
A powder having a particle size of 100 mesh or less was obtained by passing through a mesh screen. The sepiolite powder was pressure-molded to obtain a sepiolite plate.

The sepiolite plate obtained was dried at a temperature of 120 ° C for 12 hours and then baked at a baking temperature of 740 ° C for 3 hours to obtain 54 mm × 1
8 mm × 6 mm sepiolite molded body A was obtained.

The obtained sepiolite molded product A had the following physical properties.

Specific surface area: 155m ² / g (BET method) Pore volume: 0.83cc / g (30,000PSIA or less mercury injection method) Pore volume distribution: 200Å or less 0.25cc / g or less (30,000PSIA 200 to 600Å or less 0.35cc / g Below is the mercury injection method) 600-1000Å 0.08cc / g or less 1000Å or more 0.15cc / g or more Bulge strength at 45mm intervals: 1.3kg Comparative Example 1 Same as Example 1 except that the firing temperature is 350 ° C. Thus, a sepiolite molded body B was obtained.

Comparative Example 2 A sepiolite molded body C was obtained in the same manner as in Example 1 except that the firing temperature was 500 ° C.

Comparative Example 3 A sepiolite molded body D was obtained in the same manner as in Example 1 except that the firing temperature was 850 ° C.

Comparative Example 4 A sepiolite molded body E was obtained in the same manner as in Example 1 except that the kneading was performed well after the humidity control.

The obtained sepiolite molded product E had a pore volume of 1000 cc or more and a pore volume of 0.05 cc / g or less.

Comparative Example 5 Alumina zipsite obtained by the precipitation method was conditioned to a water content of about 48%, compression-molded in the same manner as in Example 1, dried and then calcined at a temperature of 600 ° C. for 2 hours to obtain 54 mm × 18 mm × 6 mm. An alumina plate was obtained.

The obtained peptiolite plates A, B, C and D were immersed in water and the peptization test was conducted.
Sepiolite plates B and C, except A and D, swelled and peptized. Therefore, it was found that the one having a low firing temperature does not have water resistance.

In addition, since the sepiolite plates B and C had a low firing temperature, organic substances such as humic acid, tannic acid, polyhydric alcohol and their esters contained in natural sepiolite were carbonized and turned black.

Sepiolite D fired at a high temperature of more than 800 ° C. was transformed into steatite, and the pores disappeared, resulting in poor porosity and embrittlement, resulting in low strength.

When the freeze non-breakage strength test was performed on the sepiolite molded body A and the alumina plate, the sepiolite molded body A was not changed, but the alumina plate was cracked and damaged.

When the heat shock test was performed on the sepiolite molded body A, the following blistering strength results were obtained.

Initial strength 1.2kg 3000 cycle product with 0.5cc water added 1.2kg 1.0cc water with 3000 cycle product 0.8kg [Effect] The sepiolite molded product of the present invention is excellent in non-destructive freezing compared with alumina plate. Compared to a sepiolite molded product that has strength and has a low firing temperature, it is excellent in non-peptizing property against water and further has high heat shock resistance.
In addition, the maximum pores of 1000 Å or more are about the same as natural products, which is a characteristic that is not found at all in the case where ground sepiolite is conditioned and then well kneaded and molded.For example, as a carrier for oxidative deodorization catalyst. When used, it facilitates free diffusion of odorous molecules and can increase catalytic activity.

In addition, it has excellent heat shock resistance, freeze non-destructive strength, and non-peptizability against water, so it is suitable for severe environments where temperature changes are severe and water is likely to be used, so it is used in those severe environments. It is extremely excellent as a catalyst carrier.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing an apparatus for testing bending strength.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Makoto Sakura               1212 Shinomiya, Hiratsuka City, Kanagawa Prefecture JGC Yu               Niversal Co., Ltd. (72) Inventor Hideyuki Yuzuki               1212 Shinomiya, Hiratsuka City, Kanagawa Prefecture JGC Yu               Niversal Co., Ltd. (72) Inventor Koji Hara               1212 Shinomiya, Hiratsuka City, Kanagawa Prefecture JGC Yu               Niversal Co., Ltd.                (56) References "Chemical technology magazine MOL" Ohm Co., Ltd.               Company, VOL. 20, No. 3 1982 3               Monthly issue p21-27, “Takero Wada New Thailand               Adsorption / thixotropic / solidifying agent Sepiolite "

Claims (4)

(57) [Claims] 1. Sepiolite is pulverized to 100 mesh or less, and this is added to water and stirred and mixed without kneading to uniformly control the moisture content of the sepiolite powder to 40 to 200 wt.%. The hydrolyzed sepiolite powder obtained by the above is pressure-molded, and the specific surface area obtained by firing at a temperature range of about 650 to 800 ° C. is 120 to 180 m ² / g, and the pore volume is 0.6 to 1.0 cc.
/ g and the pore volume of pores with a diameter of 1000Å or more is 0.15cc
A water-resistant sepiolite molded product characterized by being / g or more. 2. The pore volume distribution is 200 Å or less 0.30 cc / g or less 200 to 600Å 0.35cc / g or less 600 to 1000Å 0.10cc / g or less 1000Å or more 0.15cc / g or more The water resistant sepiolite molded article according to claim 1. 3. The flexural strength at a 45 mm interval of the water-resistant sepiolite molded body pressure-molded at a pressure of 50 kg / cm ² into a plate-like body of 54 mm × 18 mm × 6 mm is 0.8 to 2.0 kg. The water-resistant sepiolite molded article described. 4. Sepiolite is crushed to 100 mesh or less, and water is added to this to stir and mix without kneading to uniformly control the water content of the sepiolite powder to 40 to 200 wt.%. The hydrosepiolite powder obtained as described above is pressure-molded, and is fired in a temperature range of about 650 to 800 ° C. Specific surface area 120 to 180 m ² / g, pore volume 0.6 to 1.0 cc / g
And the volume of pores with a pore diameter of 1000Å or more is 0.15cc / g
The method for producing a water resistant sepiolite molded article as described above.