JPH0292843A - Production of raw material for inorganic glass foam - Google Patents

Abstract

PURPOSE:To sufficiently carry out homogeneous dispersion of reaction components and stabilize physical properties after thermal foaming by regulating a mixed powder of a natural glassy mineral having a specific particle diameter and foaming agent to a specified temperature and granulating the resultant mixture while reacting the mixture with an alkaline reaction solution. CONSTITUTION:A powder containing (A) 100 pts.wt. natural glassy mineral (e.g., obsidian, having 5-12mu average particle diameter and containing <=5% particles having >20mu average particle diameter) and (B) 0.1-5.0 pts.wt. foaming agent (e.g., carbonatey is previously regulated to <=40 deg.C. A solution consisting of 15-25 pts.wt. alkaline metal hydroxide, such as NaOH or KOH, and 7-15 pts.wt. water is then mixed therewith and the resultant mixture is granulated (to provide preferably about 2mm grain diameter) while being reacted. Thereby, formation of water glassy substances can be suppressed and a sufficient granulation time can be obtained by regulating the powder temperature to <=40 deg.C to simultaneously enhance homogeneous dispersibility.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing a granulated raw material suitable for producing an inorganic glass foam suitable as a building material.

[Traditional techniques]

Conventionally, inorganic glass foams are well known, and various low-density foams are also manufactured.

Inorganic glass foams made of natural glassy minerals generally have a high softening temperature due to their chemical composition (high Aj2zOa content), and cannot be melted unless the foam is obtained at a high temperature of 1000°C or higher, resulting in low density and fine bubbles. It was difficult to obtain a foam with a diameter. Therefore, a method of adding an alkali component to natural glass and denaturing it, followed by heating and foaming (Japanese Unexamined Patent Application Publication No. 60-36352, JP-A No. 60-77145) )It has been known.

In conventional foam manufacturing, when adding an alkaline component to natural glass to modify it, a large amount of water is used as a solvent, the mixture is mixed and kneaded to form a slurry or paste, and then dried at a temperature of 100"C or higher. After solidification, it was crushed and used as a raw material for producing foam.

[Problem to be solved by the invention]

However, in the conventional method, natural glass and alkaline components are mixed and kneaded using a large amount of water as a solvent to form a slurry or paste, and then reacted during drying, making it difficult to control the reaction and depending on the drying conditions and atmosphere. Differences in the reaction were observed depending on the difference in the amount of drying, and the difference in the center and edges of the paste or slurry that was dried. Specifically, because moisture remains in the center for a long time, the reaction progresses too much and zeolite crystals are likely to form (Reference: Llnited 5
tates Patent 3+114+603),
When crystals are generated, the physical properties after heating and foaming are reduced (higher specific gravity occurs), so the physical properties of the obtained inorganic glass foam after heating and foaming of the obtained raw material may vary depending on the areas where crystals are formed and the areas where they are not. was occurring.

In addition, in conventional manufacturing methods, slurry or paste-like materials do not completely solidify after drying, and when the solidified product is heated and foamed as it is, coarse air bubbles are formed in the center, which is unfavorable in appearance, and dry It was necessary to finely crush the solidified material.

However, even with the effort of pulverizing in this way, there are still variations in physical properties such as bulk density and vacuum water absorption of the inorganic glass foam after heating and foaming the obtained raw material.
The bubbles were also non-uniform.

As a result of intensive research into the above-mentioned problems, the present invention has found a method for solving the problems and has led to the present invention.

[Means to solve the problem]

In the present invention, at least 0.1 to 0.05% of a blowing agent is added to 100 parts by weight of natural glassy minerals having an average particle size of 5 μ to 12 μ and 5% or less of particles exceeding 20 μ.
．． A special method is to granulate the powder containing 0 parts by weight at 40° C. or lower in advance, mixing and reacting with a solution consisting of 15 to 25 parts by weight of alkali metal hydroxide and 7 to 15 parts by weight of water. This is a method for producing raw materials for inorganic glass foam.

The natural glassy minerals referred to in the present invention include obsidian, anti-firestone,
Although pearlite, pinestone, whitebait, etc. can also be used, plate glass and bottle glass, which are generally widely used, and waste glass mainly composed of powder thereof can also be used.

As the blowing agent, a powdery substance such as carbonate, nitrate, carbon, or silicon carbide that generates gas at high temperature is used. The present invention can also be carried out by appropriately adding other additives such as boron compounds. The amount of the blowing agent is 0.1 to 5.0 parts by weight based on 100 parts by weight of natural glass pseudomineral. If the amount of the blowing agent deviates from this range, the physical properties of the inorganic glass foam obtained by heating and foaming the obtained granules will deteriorate (because the specific gravity will increase).

As the alkali metal hydroxide, NaOH or KOH
is suitable.

What is important in the method of the present invention is that the powder mainly composed of natural glassy minerals and an alkali metal hydroxide solution are mixed and granulated while being reacted. Si in the glass during mixing
O□ and alkali metal hydroxide react to produce a well-known water glass (Sin, 2 Nano)-like substance, and its stickiness allows powders to adhere to each other, making granulation possible. . The present inventor found that there is a correlation between the granulation conditions and the physical properties of the resulting inorganic glass foam.

In other words, the time from the start of mixing the powder and the alkali metal hydroxide solution until the particle size of the granulated material reaches a predetermined size and granulation is stopped (hereinafter referred to as granulation time) is the natural glassy period. It has been found that the granulation time varies depending on the particle size distribution of the mineral, and if the particle size distribution of the natural glass mineral is sharp, the granulation time will be long to some extent, and if the particle size distribution is broad, the granulation time will be shortened. When the granulation time is long to a certain extent,
If the time exceeds 5 minutes, homogeneous dispersion progresses between the natural glass crystal and the alkali metal hydroxide solution before granulation, and the formation of zeolitic crystals is controlled. The present inventors have found that granules of a desired size (about 2 plates in most cases) can be obtained in this state.

That is, the natural glassy mineral used in the present invention has an average particle size of 5
μ to 12 μ, and less than 5% of particles have a particle size exceeding 20 μ. If the particle size deviates from this range, for example, if the average particle size is less than 5u, the reactivity between the powder and the alkali metal hydroxide solution will be very high, and the moment the powder and the alkali metal hydroxide come into contact, a rapid reaction will occur. A reaction occurs,
Since the particles become particles with a particle size of 10 to 20 MB within a few seconds to several tens of seconds, it becomes difficult to control the particle size of the granulated product. In addition, when the average particle size is larger than 12μ, the proportion of glassy minerals with large particle sizes increases, so the reaction between the powder and alkali metal hydroxide does not proceed, and the resulting granules are The bulk density of the glass foam obtained by heating and foaming may be extremely high.

On the other hand, even if the average particle size is 5μ to 12μ, the particle size is 20μ
If the amount exceeds 5%, sufficient granulation time will not be obtained for uniform dispersion of the powder and alkali metal hydroxide, so the bulk density of the glass foam obtained by heating and foaming the granules will decrease. The variation in the vacuum water absorption rate becomes large, and the value of the vacuum water absorption rate also becomes large. In addition, the appearance becomes poor due to the generation of coarse bubbles.

If the particle size deviates from the particle size of the present invention, or if the granulation amount is reduced, the powder and alkali It is possible to accelerate the reaction of metal hydroxide and improve the physical properties of the glass foam after heating and foaming, but when scaling up and granulating, in other words, increasing the diameter of the granulating device to improve the granulating efficiency. When increasing the temperature, the effect of heating the powder mainly composed of natural glassy minerals is canceled out, and the uniform dispersibility of the powder and alkali metal hydroxide decreases. When scaling up in this way, the granulation time is generally shortened, so the average particle size of natural glassy minerals is 5μ to 12μ, and 5% of the particles exceed 20μ.
Even if it is below, the uniform dispersibility of the powder mainly composed of natural glassy minerals and the alkali metal hydroxide will decrease. Therefore, in the present invention, the temperature of powder mainly composed of natural glassy minerals is set to 4.
By keeping the temperature below 0°C, water glass (SiO□・2Na), which is a reaction product of Sing and alkali metal hydroxide, is
This suppresses the formation of zO)-like substances, provides sufficient granulation time, and improves uniform dispersibility. - On the other hand, even if the particle size of the natural glassy minerals is the same, if the temperature of the powder mainly composed of natural glassy minerals is raised to 50°C before adding the alkali metal hydroxide aqueous solution, a large amount of In the case of granulation, it becomes impossible to uniformly react the natural glassy mineral and the alkali metal hydroxide before granulation, making it impossible to obtain granules having desired properties. However, for example, 5! On a small scale that can be granulated using a granulator, the desired product can be obtained even at temperatures above 40°C.

The composition of the aqueous solution of alkali metal hydroxide used in the present invention is preferably 15 to 25 parts by weight of alkali metal hydroxide and 7 to 15 parts by weight of water based on 100 parts by weight of natural glassy mineral.

If the alkali metal hydroxide is less than 15 parts by weight, the expansion ratio during heat foaming will be low and it will be difficult to obtain a glass foam with a low specific gravity.
Moreover, if it exceeds 25 parts by weight, although the specific gravity is lowered, unreacted alkali metal hydroxide tends to remain, which reduces the water resistance and durability of the obtained glass foam, which is not preferable.

Furthermore, if the amount of water is less than 7 parts by weight, high temperatures are required to dissolve the alkali metal hydroxide, and special equipment is required, which is not preferable. If the amount of water exceeds 15 parts by weight, it is difficult to obtain a granulated product, which is not preferable because it becomes slurry-like.

Mechanical devices for mixing and reacting the powder mainly composed of the natural glassy mineral and the aqueous solution of alkali metal hydroxide to form granules include various mixers and granulators, such as transfer rotary granulators. , a high-speed rotary vane-type mixing granulator, etc. can be used, but in order to more reliably control the temperature rise of the granules, that is, control the reaction, it is recommended to use a granulator equipped with a cooling mechanism such as Jaquent. , the stability of the resulting granules becomes higher.

The particle size of the obtained granules can be arbitrarily controlled by the granulation time and method, but it is preferably 5M or less, particularly preferably about 2M, in order to make the bubbles of the glass foam uniform after heating and foaming. preferable.

Further, the obtained granules may be used as they are for heating and foaming, but may be dried in a temperature range of 60 to 200° C. to further promote the reaction.

The temperature for heating and foaming can be set depending on the amount of alkali metal hydroxide contained, but is preferably 650 to 850°C.

After granulation, to obtain a glass foam molded product, the granules can be placed uniformly at the bottom of a heat-resistant mold made of stainless steel or the like according to the density of the molded product, and heated. A glass foam molded article having an arbitrary shape can be obtained by making use of the adhesive properties of the granules to make them adhere to each other, pre-forming them into an arbitrary shape, and heating and foaming them.

When the raw material obtained by the production method of the present invention is heated and foamed as described above, the bulk specific gravity is 0.17 to 0.21.
g/cm', a vacuum water absorption rate of 6Vo1% or less, and a maximum cell diameter of approximately 4s or less, an inorganic glass foam with good appearance can be obtained with high accuracy.

〔Example〕

Hereinafter, the manufacturing method of the present invention will be explained in detail with reference to Examples.

The average particle diameter, bulk density, and vacuum water absorption rate as used in the present invention are determined by the following method.

a) Average particle size This is the median diameter determined by a light transmission measurement method using natural and centrifugal precipitation methods using water as a dispersion medium.

b) Cut the bulk density foam into a cube shape of about 5 c1n on each side, measure its weight (g) and dimensions (length, width, height), and calculate it using the following formula.

C) Vacuum Water Absorption Rate After measuring the weight and dimensions of a cubic sample of approximately 5 cm on a side in the same manner as bulk density measurement, it was degassed for 60 minutes under a vacuum of 760 Hg, and then immersed in water for 60 minutes under the same vacuum. Let it absorb water. Thereafter, the sample is taken out, the water adhering to the surface is wiped off, the weight is measured, and the weight is calculated using the following formula.

Space volume in sample (am') - [Length (cm) Obsidian powder A with the sharp particle size distribution shown in middle and ■ (from Wada Pass, average particle size 7.2μ, 4% for particles exceeding 20μ) 100 parts by weight (3kg), CaC0t
+, an effective volume of powder consisting of 5 parts by weight and 3.5 parts by weight of borax aqua regia is 5I! When mixed for 5 minutes using a transfer rotary granulator (manufactured by Nippon Eirich), the temperature of the powder was 52°C. This was mixed with a solution of 20 parts by weight of NaOH in 10 parts by weight of water, and granulated without reacting until the particle size of the granulated product became about 2 kats. Granulation time was 6 minutes and 30 seconds. The granules were dried at 200'C for 2 hours.

Put 300g of this grain into an aluminum foil container and heat it in a gas furnace for 7
After raising the temperature to 40°C in 2 hours and holding it for 10 minutes,
It was sufficiently slowly cooled and taken out to obtain an inorganic glass foam.

This foam had a bulk density of 0.19 g/cm3, a vacuum water absorption rate of 4.7 Vo1%, a maximum cell size of 3, and had a good appearance.

Comparative Example 1 100 parts by weight of obsidian powder A used in Example 1 (30 kg
), 5 parts by weight of CaC011, and 3.5 parts by weight of borax aqua regia were mixed for 5 minutes in a rotating rotary granulator (manufactured by Nippon Airinch) with an effective volume of 75β. This powder was heated at 50°C.
After heating to 10% water using a 752 rotating rotary granulator,
The mixture was mixed with a solution in which 20 parts by weight of NaO was dissolved in 1 part by weight, and granulated without reaction until the particle size of the granulated product became about 2 mm.

Granulation time was 3 minutes. The granules were dried at 200"C for 2 hours.

The particles were heated and foamed under the same conditions as in Example 1 to obtain an inorganic glass foam.

This foam has a bulk density of 0.22 and a vacuum water absorption rate of 7.9 Vo.
1%, and bubbles with a maximum size of 5 bars were observed.

Example 2 Granulation was carried out using the same composition and under the same conditions as in Example 1, except that the temperature of the powder at the start of granulation was 36°C. The granulation time was 10 minutes and 30 seconds. The granules are heated to 200°C.
Dry for an hour.

Table 2 shows the bulk density, vacuum water absorption rate, and maximum cell diameter of the inorganic glass foam obtained by heating and foaming these particles under the same conditions as in Example 1.

Example 3 Granulation was carried out using the same composition and under the same conditions as Comparative Example 1, except that the temperature of the powder at the start of granulation was 38°C. Granulation time was 6 minutes. The granules were dried at 200°C for 2 hours.

Table 2 shows the bulk density, vacuum water absorption rate, and maximum cell diameter of the inorganic glass foam obtained by heating and foaming these particles under the same conditions as in Example 1.

Example 4 Granulation was carried out using the same composition and under the same conditions as Comparative Example 1, except that the temperature of the powder at the start of granulation was 18"C.

Granulation time was 8 minutes. The granules were dried at 200°C for 2 hours.

Table 2 shows the bulk density, vacuum water absorption rate, and maximum cell diameter of the inorganic glass foam obtained by heating and foaming these particles under the same conditions as in Example 1.

Example 5 Without drying the granules obtained in Example 1, the size of the granules was 6 cm x 6 cra x 3 due to the adhesive strength of the granules themselves.
The hexahedron shaped into a cm-sized hexahedron was heated and foamed under the same conditions as in Example 1.

The bulk density of the obtained inorganic glass foam was 0.18,
The vacuum water absorption rate was 5.7 Vo1%. The maximum bubble size was 3 mm.

Example 6 Obsidian powder A 100 parts by weight (3 kg) used in Example 1
When powder consisting of 0.1.0 parts by weight of CaC was mixed for 5 minutes in the same granulator as in Example 1, the temperature of the powder was 4.
The temperature was 7°C. To this, add 12 parts by weight of water (Nap) 122.
5 parts by weight? Did you tolerate it? The mixture was mixed and reacted until the granules had a particle size of about 2 mm. Granulation time was 6 minutes. The granules were dried at 200"C for 2 hours.

The particles were heated and foamed under the same conditions as in Example 1 to obtain an inorganic glass foam.

This foam has a bulk density of 0.17 and a vacuum water absorption rate of 6.0 Vo.
1%, and the maximum bubble size was 4M.

Example 7 100 parts by weight of obsidian powder A used in Example 1 (30 kg
), 2.5 parts by weight of CaCO, and 2.0 parts by weight of borax aqua regia were mixed for 5 minutes in the same granulator as in Comparative Example 1, and the temperature of the powder was 49°C. . After cooling this powder to 30°C by leaving it at room temperature, a solution of 118 parts by weight of Nap) dissolved in 10 parts by weight of water was mixed and granulated without reaction until the particle size of the granulated product became approximately 2 + mA. .

Granulation time was 7 minutes. The granules were dried at 200'C for 2 hours.

The particles were heated and foamed under the same conditions as in Example 1 to obtain an inorganic glass foam.

This foam has a bulk density of 0.19 and a vacuum water absorption rate of 5.0 Vo.
1%, and the maximum bubble size was 3 bubbles.

Comparative Examples 2 and 4 Obsidian powder B shown in Table 1 (the particle size distribution shown in Granulation was performed with the same composition and under the same conditions as in Example 1. The granulation times are shown in Table 2. The granules were dried at 200° C. for 2 hours.

Table 2 shows the bulk density, vacuum water absorption rate, and maximum cell diameter of the inorganic glass foam obtained by heating and foaming these particles under the same conditions as in Example 1.

Comparative Examples 3 and 5 Obsidian powder B was used and granulation was performed under the same composition and conditions as Comparative Example 1, except that the temperature of the powder at the time of starting granulation was changed, as shown in Table 2. Ta. Granulation times are shown in Table 2. The granules were dried at 200°C for 2 hours.

Table 2 shows the bulk density, vacuum water absorption rate, and maximum cell diameter of the inorganic glass foam obtained by heating and foaming these particles under the same conditions as in Example 1.

Comparative Example 6 Obsidian powder C shown in Table 1 (particle size distribution shown by ■ in Figure 1) was used, except that the temperature of the powder at the start of granulation was changed as shown in Table 2. Granulation was carried out using the same composition and under the same conditions as in Example 1. Granulation time was 3 minutes.

The granules were dried at 200°C for 2 hours.

The bulk density of the GL glass foam obtained by heating and foaming these particles under the same conditions as in Example 1 was as high as 0.37.

Comparative Example 7 The same procedure as Example 1 was used except that obsidian powder D shown in Table 1 (broad particle size distribution shown by ■ in Figure 1) was used and the temperature of the powder at the time of starting granulation was 36°C. Granulation was attempted with the same composition and under the same conditions, but within 30 seconds after the start of granulation, the diameter was 10-2.
0nun coarse grains 1. It was difficult to control the particle size of the granules.

Comparative Example 8 Obsidian powder A100 parts by weight shown in Table 1, CaC0z
A mixture consisting of 1.5 parts by weight of borax trihydrate and 3.5 parts by weight of borax trihydrate was mixed with a solution of 120 parts by weight of Nap) dissolved in 35 parts by weight of water using a universal stirrer. The mixture became a paste, which was transferred onto a vat and dried at 200° C. for 5 hours to a thickness of approximately 2 mm.

When the obtained solidified plate-like material was finely ground, placed in a mold, and heated and foamed under the same conditions as in Example 1, the bubbles were extremely uneven, the bubble size was up to 6 plates, and the appearance was poor. there were.

(Effects of the invention) By using the method of the present invention, natural glassy minerals and alkali metal hydroxides are sufficiently uniformly dispersed, and the resulting granules have high uniformity and reactivity, resulting in heat foaming. Stabilizes subsequent physical properties.

In addition, compared to the method of obtaining a paste or slurry, it is possible to heat and foam a solidified solid product without pulverizing it to obtain a foam with a uniform cell shape. Further, according to the present invention, even if a large amount of granulation is performed, the performance of the obtained granules does not deteriorate, and the obtained granules are heated and foamed into a predetermined shape. The inorganic glass foam can be obtained with little variation in bulk density and vacuum water absorption, and with small values of bulk density and vacuum water absorption.

[Brief explanation of drawings]

FIG. 1 is a graph showing the particle size distribution of obsidian powder used in Examples and Comparative Examples. Note that the horizontal axis is in logarithmic representation. Table 1 Table 2 *The temperature of the powder is the temperature at the start of granulation.

Claims (1)

[Claims] The average particle size is 5μ to 12μ, and the particle size is 20μ.
10 natural glassy minerals with less than 5% of those exceeding μ
Powder containing at least 0.1 to 5.0 parts by weight of a blowing agent per 0 parts by weight is preheated to 40°C or below, and mixed with 15 to 25 parts by weight of alkali metal hydroxide and 7 to 15 parts by weight of water. A method for producing a raw material for an inorganic glass foam, characterized by granulating it while mixing and reacting with a solution.