JPH0292842A - Production of granulated substance for inorganic glass form - Google Patents

Abstract

PURPOSE:To enable use of a granulated substance as a raw material for glass foams without pulverizing the above-mentioned substance and reduce dispersion of bulk density and vacuum water absorption coefficient by adding a foaming agent and aqueous solution of an alkali to a natural glassy mineral having a specific particle diameter and granulating the resultant mixture while reacting the mixture. CONSTITUTION:A powder containing (A) 10 pts.wt. natural glassy mineral (e.g., obsidian, perlite or silas, having 5-12mu average particle diameter and containing <5% particles having >20mu particle diameter) and (B) 0.1-5.0 pts.wt. foaming agent (e.g., carbonate nitrate or carbon) is mixed with a solution consisting of 15-20 pts.wt. alkaline metal hydroxide, such as NaOH or KOH, and 7-15 pts.wt. water and the resultant mixture is granulated (to provide preferably about 2mm grain diameter) while being reacted to afford a granulated substance suitable for producing an inorganic glass foam suitable as building materials.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing granules suitable for producing inorganic glass foams suitable as building materials.

[Traditional techniques]

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

Inorganic glass foams made from natural glassy minerals generally have a high softening temperature due to their chemical composition (high Aj!zOs content), and cannot be melted unless the foam is obtained at a high temperature of 1000°C or higher, resulting in a low density. It was difficult to obtain a foam with a fine cell size.

Therefore, a method is known in which natural glass is denatured by adding an alkali component and then heated and foamed (Japanese Unexamined Patent Publications Nos. 60-36352 and 60-77145).

In conventional foam production, when adding an alkaline component to natural glass to modify it, a large amount of water as a solvent is used, 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, moisture remains in the center for a long time, so the reaction progresses too much and zeolite crystals are likely to form (Reference: United 5t
ates Patent 3+114+603), when crystals are generated, the physical properties after heating and foaming are reduced (because the specific gravity becomes high), so the inorganic glass after heating and foaming of the obtained raw material is There were variations in the physical properties of the foam.

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]

That is, the present invention has an average particle size of 5 μ to 12 μ,
Furthermore, at least 0 blowing agent is added to 100 parts by weight of natural glassy minerals in which 5% or less of particles with a particle size exceeding 20μ are present.
．． A powder containing 1 to 5.0 parts by weight is mixed with a solution containing 15 to 25 parts by weight of an alkali metal hydroxide and 7 to 15 parts by weight of water and granulated while reacting. This is a method for producing granules for inorganic glass foam.

What is the natural glassy mineral referred to in the present invention? Obsidian, anti-firestone, pearlite, pine rock, shirasu, etc. can also be used, but 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 foaming agent is natural glassy mineral 100%
The amount is 0.1 to 5.0 parts by weight. 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 containing natural glass minerals is mixed with an alkali metal hydroxide solution and granulated while being reacted. Si in the glass during mixing
The reaction between O and the alkali metal hydroxide produces a water glass (Sing・2 Name)-like substance, which is well known in -a, and its stickiness allows the powders to adhere to each other, making granulation possible. Become. 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 product reaches a predetermined size and granulation is stopped (hereinafter referred to as granulation time) is the time required for the Natural Glass Award. 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,
In most cases, when the time exceeds 5 minutes, homogeneous dispersion between the natural glassy mineral and the alkali metal hydroxide solution progresses before granulation, and the formation of zeolite crystals is controlled, and the process continues in that state. The present inventors have discovered that granules of a desired size (about 2a11 in most cases) can be obtained. That is, the natural glassy mineral used in the present invention has an average particle size of 5μ to 12μ.
Moreover, less than 5% of the particles have a particle size exceeding 20μ. If the particle size deviates from this, for example, the average particle size is 5μ.
When it is less than Since the particles have a diameter of IO to 20 mm, 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.

The composition of the aqueous solution of alkali metal hydroxide is 15 to 15 parts by weight of alkali metal hydroxide per 100 parts by weight of natural glassy mineral.
25 parts by weight and 7 to 15 parts by weight of water are preferred.

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.

In addition, if the water content is less than 7 parts by weight, high temperatures are required to dissolve the alkali metal hydroxide and special equipment is required, which is undesirable. This is not desirable.

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 rotating vane type mixing granulator, etc. can be used.

The particle size of the obtained granules can be arbitrarily controlled by the granulation time and method, but in order to make the bubbles of the glass foam uniform after heating and foaming, it is preferably 5rm or less, particularly preferably 2III
It is preferable to set it to about 1.

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.

〔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 refers to the median diameter determined by a light transmission measurement method using natural and centrifugal sedimentation methods using water as a dispersion medium.

b) Cut the bulk density foam into a cube shape of about 5C1!1 on a side, measure its weight (to) and dimensions (length, width, height), and calculate it using the following formula.

C) Reduced pressure water absorption After measuring the weight and dimensions of a cubic sample of about 5 CI11 on each side in the same way as bulk density measurement, under reduced pressure of 760 mmHg,
After degassing for a minute, it is immersed in water for 60 minutes under the same reduced pressure to 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 the sample (cl) = [Length (cn+) ) Example 1 Obsidian (from Wada Pass) with an average particle size of 8.8μ was classified to obtain obsidian powder with a sharp particle size distribution shown in ■ in Figure 1.The average particle size of this obsidian powder was 6.8μ. 1μ, and 0% of grains exceeding 20μ.Kome obsidian 100
A mixture consisting of 1.5 parts by weight, 31.5 parts by weight of CaCO, and 3.5 parts by weight of rainwater borax and a solution of 20 parts by weight of NaOH dissolved in 10 parts by weight of water were mixed and reacted using a transfer rotary granulator (manufactured by Nippon Eirich). The granules were granulated until the particle size of the granulated product became approximately 2 mm. When this granulation was performed 10 times, the granulation time was in the range of 7 to 9 minutes.

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

300 g of the obtained 10 batches of granulated material was placed in an aluminum foil container, heated to 735°C in a gas furnace for 2 hours, held for 10 minutes, cooled sufficiently, taken out, and heated to 735°C in a gas furnace for 2 hours. An inorganic glass foam was obtained.

The bulk density of these 10 foams was 0.18 to 0.20, and the vacuum water absorption rate was 3.5 to 4.4 Vo1%, and the variation was very small. The maximum bubble size was 2 circles, and the appearance was very good.

Example 2 100 parts by weight of obsidian used in Example 1, CaC0°1.
0 parts by weight of NaOH23 to 12 parts by weight of water.
A solution in which part by weight was dissolved was granulated using the same granulator as in Example 1 until the particle size of the granulated product became about 2 mm. Granulation time was 6 minutes. The granules were dried at 200°C for 2 hours.

The obtained granules were heated and foamed under the same conditions as in Example 1,
An inorganic glass foam was obtained.

The bulk density of this foam is 0.17, the vacuum water absorption rate is 6,
The I Vo was 1%, and the maximum bubble size was 4 mm.

Example 3 100 parts by weight of obsidian used in Example 1, CaCO536
A mixture consisting of 0 parts by weight, 3.5 parts by weight of rainwater borax, and 1 part by weight of water.
A solution prepared by dissolving 18 parts by weight of NaOH in 0 parts by weight was granulated using the same granulator as in Example 1 until the particle size of the granules became about 2 mm. Granulation time was 8 minutes. Granules are 20
It was dried at 0°C for 2 hours.

The obtained granules were heated and foamed under the same conditions as in Example 1,
An inorganic glass foam was obtained.

The bulk density of this foam is 0.20, and the vacuum water absorption rate is 5.3.
The Vo was 1%, and the bubble size was 3 mm at maximum, which was good.

Example 4 Obsidian powder with particle size distribution shown in ■ in Figure 1 (produced from Wada Pass, average particle size 7.2μ, 4% with particle size exceeding 20μ)
), the composition was the same as in Example 1, and the same granulator was used to granulate the granules until the particle size of the granules was about 2 mm. When this granulation was performed 10 times, the granulation time was in the range of 6 to 8 minutes.

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

The obtained granules for 10 times were heated and foamed under the same conditions as in Example 1 to obtain 10 inorganic glass foams.

The bulk density of these 10 foams was 0.18 to 0.21, the vacuum water absorption rate was 4.1 to 5.2 Vo1%, and the cell size was 3 at most, which was good.

Example 5 Without drying the granules obtained in Example 1 for 10 times, the adhesive strength of the granules themselves made 5 C1l each.
The hexahedron of 6 cm x 3 cm was heated and foamed under the same conditions as in Example 1 to obtain 10 inorganic glass foams.

The bulk density of these 10 foams was 0.17 to 0.20, the vacuum water absorption rate was 4.0 to 5.7 Vo1%, and the cell size was 3 circles at maximum, which was good.

Comparative Example 1 Obsidian (from Wada Pass) with an average particle size of 8.8 μm was classified to obtain obsidian powder having a particle size distribution shown in ■ in FIG. The average particle size of this obsidian powder was 8.4μ, and 10.2% had a particle size exceeding 20μ. Using this obsidian powder, it was granulated using the same composition and the same granulator as in Example 1 until the particle size of the granulated product was about 2 mm. When this granulation was performed 10 times, the granulation time was in the range of 2 to 5 minutes. The granules were dried at 200°C for 2 hours.

The obtained granules for 10 times were heated and foamed under the same conditions as in Example 1 to obtain 10 inorganic glass foams.

The bulk density of these 10 foams was 0.20 to 0.24, and the vacuum water absorption rate was 5.0 to 8.5 νo1%, indicating that the bulk density was high. The maximum bubble size was 4 bubbles.

Comparative Example 2 In Figure 1, obsidian powder with the particle size distribution shown in
4%), the composition was the same as in Example 1, and the same granulator was used to granulate the granules until the particle size of the granules was approximately 2 mm. When this granulation was performed 10 times, the granulation time was in the range of 1 to 3 minutes.

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

The obtained granules for 10 times were heated and foamed under the same conditions as in Example 1 to obtain 10 inorganic glass foams.

The high densities of these 10 foams varied from 0.15 to 0.24, and the vacuum water absorption rates were as large as 10.21 to 18.1%. Moreover, the bubble size was up to 8 nm+, and the appearance was poor.

Comparative Example 3 Using obsidian powder with an average particle size of 4.8 μm and having a broad particle size distribution shown in ■ in Figure 1 (produced from Wada Pass, 11% of particles having a particle size exceeding 20 μm), the same composition as in Example 1 was used. When granulation was performed using the same granulator, the particle size became 10 to 20 mm approximately 30 seconds after the start of granulation, making it difficult to control the particle size of the granulated product.

Comparative Example 4 Average particle size 16.2μ with particle size distribution shown in ■ in Figure 1
Obsidian powder (from Wada Pass, 46 for those with particle size over 20μ)
%), the composition was the same as in Example 1, and the same granulator was used to granulate the granules until the particle size of the granules became about 2 koi. Granulation time was 3 minutes. The granules were dried at 200'C for 2 hours.

The obtained granules were heated and foamed under the same conditions as in Example 1,
An inorganic glass foam was obtained.

The bulk density of this foam is 0.37, and the vacuum water absorption rate is 10.5.
%Met.

Comparative Example 5 20 parts by weight of NaOH was dissolved in 35 parts by weight of water and a mixture consisting of 100 parts by weight of obsidian powder (produced in Wada Pass) with an average particle size of 8.8 μ, 0.1.5 parts by weight of CaC, and 3.5 parts by weight of rainwater borax. The solution was mixed using a universal stirrer. The mixture becomes a paste and is transferred onto a vat to a thickness of about 2m.
Dry at 0''C for 5 hours.

When the obtained solidified plate-like material was finely pulverized, placed in a mold, and heated and foamed under the same conditions as in Example 1, the cells were found to be extremely uneven, with a maximum cell size of 6III11, and the appearance was poor. Ta.

〔Effect of the invention〕

According to the method of the present invention, the obtained granules can be shaped into a predetermined shape without being crushed and used as a raw material for heating and foaming, and the granules have a diameter of about 2 dragons, which is easy to use. Moreover, the inorganic glass foam obtained by heating and foaming the obtained granules into a predetermined shape,
It is possible to obtain a material with little variation in bulk density and vacuum water absorption, and small values of bulk density and vacuum water absorption.

BRIEF DESCRIPTION OF THE 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. Patent applicant: Asahi Kasei Industries, Ltd.

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, and 15 to 2 parts by weight of an alkali metal hydroxide.
A method for producing a granulated product for an inorganic glass foam, which comprises granulating while mixing and reacting 5 parts by weight with a solution consisting of 7 to 15 parts by weight of water.