JPH04280883A - Inorganic composition for producing incombustible inorganic foamed material - Google Patents

Abstract

PURPOSE:To obtain an inorganic composition capable of producing a sufficiently cured inorganic foamed material having high quality and useful as an incombustible and non-smoking heat-insulation material by stabilizing the reactivity of an inorganic fine powder composed of silica sand, fly ash, calcined bauxite, etc., and improving the activity of the powder. CONSTITUTION:The objective inorganic composition for the production of incombustible inorganic foamed material is composed of an aqueous solution of an alkali metal silicate, an inorganic solid component, a filter and a foaming agent. The inorganic solid component is produced by coating the surface of inert or low-activity inorganic fine powder with an active component composed of alumina sol and/or silica sol.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to inorganic compositions used for producing inorganic foams useful, for example, as nonflammable heat insulating materials.

0002

[Prior Art] Generally, inorganic foams are extremely useful as non-combustible and non-smoke heat insulating materials.
Non-flammable inorganic foams made from compositions of aqueous alkali metal silicate solutions, finely divided minerals, fillers and blowing agents are already known.

0003

[Problems to be Solved by the Invention] In such conventional inorganic compositions for producing nonflammable inorganic foams, an oxidized mixture consisting of amorphous silicon oxide and alumina oxide is used as the finely powdered inorganic substance. For example, metakaolin, corundum, ash from electrostatic precipitators generated during the production of mullite, pulverized bauxite, fly ash, etc. are known, but these components vary in their reactivity during molding. However, there was a problem that the degree of activity was not constant.

[0004] In order to solve the above problems, the inventors have conducted extensive research and found that in order to stabilize the reactivity of finely powdered inorganic materials and increase their activity, it is necessary to use inert or small active finely powdered inorganic materials. A stable reactive inorganic solid component can be formed by coating the active ingredient on the surface of They discovered that it was possible to obtain a sufficiently cured inorganic foam, and completed this invention.

The purpose of the present invention is to stabilize the reactivity of finely powdered inorganic materials, increase their activity, and produce a sufficiently cured, high-quality inorganic foam that is extremely useful as a non-combustible and non-smoke heat insulating material. The aim is to provide an inorganic composition that can

[0006]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides an inorganic composition comprising an aqueous alkali metal silicate solution, an inorganic solid component, a filler, and a blowing agent, the inorganic solid component comprising: An inorganic composition for producing a nonflammable inorganic foam, characterized in that the surface of an inert or active small finely powdered inorganic material is coated with an active ingredient consisting of at least one of alumina sol and silica sol. This is the summary.

[0007] In the above, as the aqueous alkali metal silicate solution, an aqueous solution of potassium silicate, sodium silicate, or a mixture thereof is used.

The composition of such an aqueous solution is SiO2 and K2O, SiO2 and Na2O, or SiO2
and K2O+Na2O, the molar ratio of each is 1.0 to 3.0, and the concentration of the aqueous solution is 30 to 6
A range of 0% is preferred.

[0009] The finely powdered inorganic substance as the inorganic solid component may be one that has no activity at all, or it may be one that has insufficient activity and is difficult to use alone.

[0010] Here, examples of inert fine powder inorganic substances include silica sand, alumina, kaolin, calcium carbonate, talc, mica, aluminum hydroxide, and glass powder. Additionally, examples of small active finely divided inorganic materials include fly ash, calcined kaolin, calcined bauxite,
and ash from electrostatic precipitators generated during the production of corundum or mullite.

[0011] Generally, the smaller the particle size of the finely powdered inorganic material is, the better; however, if it becomes too small, the coating of the active ingredient tends to be uneven, so it should be about 0.1 to 100 μm,
The thickness is preferably about 0.2 to 50 μm.

[0012] The active ingredients to be coated on the surface of such inert or small active finely powdered inorganic materials include:
Alumina sols and/or silica sols can be used.

[0013] Here, the alumina sol is Al2O3
It is sufficient that the quality crystal system is alumina hydrate, and the particle shape may be feather-like, plate-like, rod-like, or granular. Further, the alumina sol dispersion is an acidic aqueous solution to which one of hydrochloric acid, acetic acid, and nitric acid is added as a stabilizer.

[0014] The silica sol has a SiO2 particle size of 0.
A material with a diameter of 2 μm or less is applicable. When used alone, the liquid phase is an aqueous solution that is either acidic or basic.

Furthermore, when alumina sol and silica sol are used in combination, the dispersion liquid should be acidic, and the ratio of Al2 O3 to SiO2 should be 20% by weight or more.

Coating the surface of an inert or small active finely powdered inorganic material with an active ingredient consisting of at least one of alumina sol and silica sol,
To form an inorganic solid component, a predetermined amount of an aqueous solution of alumina sol and/or silica sol is coated on a predetermined amount of an aqueous solution of alumina sol and/or silica sol by a spray method while stirring a finely powdered inorganic material placed in a predetermined container, and the contents are taken out and heated at around 100°C. After drying at a high temperature and pulverizing the obtained lumps, approximately 300 to 800
It is fired at a temperature of ℃.

The amount of active ingredient added is determined by the particle size of the inert or small active powder. In other words, the smaller the particle size of the powder, the greater the appropriate amount to add.
Generally about 5-20% by weight is preferred.

The above-mentioned filler may also include inorganic substances in crushed or finely divided form, such as rock powder, basalt, feldspars, mica, silica sand, glass powder, alumina, aluminum hydroxide, talc, fiber materials, and other inert or Various water-insoluble minerals can be used. These fillers are
They are appropriately selected depending on the use of the inorganic foam and are used alone or in combination.

As the blowing agent, sodium perborate, hydrogen peroxide solution, aluminum powder, etc. are used.

The blending ratio of each component of the above-mentioned inorganic composition for producing a nonflammable inorganic foam is as follows: 100 parts by weight of an inorganic solid component, which is an inert or small active finely powdered inorganic material coated with an active ingredient; Metal silicate aqueous solution 4
0 to 100 parts by weight of the blowing agent, and 10 to 30 parts by weight of the filler, and 2 to 30 parts by weight of the blowing agent per 100 parts by weight of the main material consisting of these inorganic solid components, aqueous alkali metal silicate solution, and filler. and preferably,
The foaming agent is used in an amount of 5 to 15 parts by weight based on 100 parts by weight of the main material. Here, if the blowing agent is less than 2 parts by weight with respect to 100 parts by weight of the main material, the foaming effect will be small, and if the blowing agent exceeds 30 parts by weight, the density of the foamed molded product will be very low and compression This is not preferred because the strength decreases.

[0021] The specific formulation of each component of the inorganic composition can be arbitrarily determined depending on the method of molding the inorganic foam or the intended use.

In order to produce a nonflammable inorganic foam from the above-mentioned inorganic composition, first, an inorganic solid component is prepared by coating an active ingredient on the surface of an inert or small active finely powdered inorganic material, a filler, and an appropriate amount if necessary. Pigments and the like are added and mixed, and then an aqueous alkali metal silicate solution, which is a liquid component, is added and kneaded until these are sufficiently dispersed. Next, a foaming agent is added to this kneaded material, and after mixing these, the mixture is poured into a predetermined mold and heated to 40 to 80
The inorganic composition is foamed and cured by heating in an oven at 0.degree. C. for 1 to 4 hours to obtain an inorganic foam having a predetermined shape.

[0023]

[Function] According to the above-mentioned inorganic composition for producing a nonflammable inorganic foam, the inorganic solid component is obtained by coating the surface of an inert or small active finely powdered inorganic material with an active component consisting of alumina sol and/or silica sol. Because of this, it is possible to stabilize the reactivity of the finely divided inorganic material, increase its activity, and produce a sufficiently cured, high-quality inorganic foam.

[0024]

EXAMPLES Next, examples of the present invention will be explained together with comparative examples.

Example 1 100 parts by weight of silica sand powder with an average particle size of 3 μm as a finely powdered inorganic substance was placed in a rotary kneader, and while stirring, 10% by weight of Al2O3 as an active ingredient was added by spraying.
After the alumina sol aqueous solution was coated so that the alumina sol amounted to 50 parts by weight, the contents were taken out and dried at 110° C., and the resulting lumps were pulverized. The mixture was then calcined at 300° C. for 2 hours to obtain a reactive inorganic solid component A.

As shown in Table 1 below, after mixing 100 parts by weight of reactive inorganic solid component A with 9 parts by weight of talc and 6 parts by weight of mica as fillers, K2
15.3% by weight of O, 7.7% by weight of Na2O, Si
60 parts by weight of an aqueous potassium/sodium silicate solution having a composition of 24.9% by weight of O2 and 52.1% by weight of H2O was added and thoroughly kneaded using a conventional mixer.

Next, 10 parts by weight of a 10% by weight hydrogen peroxide solution as a blowing agent is added to this kneaded mixture and mixed to obtain an inorganic composition for producing a nonflammable inorganic foam. Immediately, the inner dimensions are 100mm long x 100mm wide.
Pour into a thermosetting resin mold measuring 200 mm x 200 mm in height, cover with a moisture-impermeable covering material in advance to prevent the moisture inside from dissipating to the outside during subsequent heating, and heat for about 10 minutes. The inorganic composition was allowed to foam.

After the inorganic composition was completely foamed, it was heated in an oven at 85° C. for 4 hours. The content thus obtained was a fully cured inorganic foam.

[0029] The above inorganic foam was
After cutting into a size of mm x height 50 mm and drying it in an oven at 50°C for 2 hours, the density and compressive strength of the obtained inorganic foam (measurement method is JIS A
9514) was measured. In addition, the cured state of the obtained inorganic foam was observed, and the results are summarized in Table 1.

Example 2 100 parts by weight of fly ash having an average particle size of 15 μm as a finely powdered inorganic material was placed in a rotary kneader, and while stirring, Al2O3 as an active ingredient was sprayed.
After coating a mixed aqueous solution of 10 wt% alumina sol and 20 wt% SiO2 silica sol so that the alumina sol was 50 parts by weight and the silica sol was 25 parts by weight, the contents were taken out and the following procedure was carried out in the same manner as in Example 1. As a result, a reactive inorganic solid component B was obtained.

Next, this reactive inorganic solid component B was blended according to the proportions shown in Table 1, and an inorganic foam was produced in the same manner as in Example 1 above. The compressive strength of the obtained inorganic foam was measured in the same manner, and the results are shown in Table 1 together with the cured state and density of the inorganic foam.

Example 3 100 parts by weight of calcined bauxite with an average particle size of 25 μm as a finely powdered inorganic material was placed in a rotary kneader, and while stirring, SiO2 2 as an active ingredient was sprayed.
Example 1 above except that after coating a 0% by weight silica sol aqueous solution so that the silica sol amount was 60 parts by weight, the contents were taken out and baking was performed at 400°C for 90 minutes.
A reactive inorganic solid component C was obtained in the same manner as in the case of .

Next, this reactive inorganic solid component C and the inorganic solid component B obtained in Example 2 are shown in Table 1.
The mixing ratio shown in (the potassium/sodium silicate aqueous solution is 1
00 parts by weight) and leave it in the mold for 15 minutes.
An inorganic foam was produced in the same manner as in Example 1 above, except that the test was carried out for a minute. The compressive strength of the obtained inorganic foam was measured in the same manner, and the results are shown in Table 1 together with the cured state and density of the inorganic foam.

Comparative Examples 1 to 3 For comparison, the surfaces of the finely powdered inorganic materials of Examples 1 to 3, that is, silica sand, fly ash, and calcined bauxite, were used as they were without activation, and the components were The blending ratio, kneading, foaming, hot molding, drying, and firing were carried out in the same manner as in Examples 1 to 3 to produce three types of inorganic foams for comparison. The obtained inorganic foam was not sufficiently cured even after heating and was still in a soft state, and these results are also shown in Table 1.

The cured state of the inorganic foam was evaluated as follows.

○: The foamed molded product is sufficiently solidified and can be taken out from the container and cut out. ×: The foam molded product was not sufficiently solidified and was too soft to be removed from the container.

[0037]

[Table 1]

As is clear from the results in Table 1 above, according to the inorganic compositions of Examples 1 to 3 of the present invention, the inorganic solid component was formed on the surface of the inert or small active finely powdered inorganic material, such as alumina sol, Alternatively, since we use a product coated with active ingredients consisting of alumina sol and silica sol, the reactivity of the fine powdered inorganic material is stabilized and its activity is increased, resulting in an extremely good curing state and a very high compressive strength. We were able to obtain a high quality inorganic foam.

On the other hand, the inorganic foams of Comparative Examples 1 to 3, in which the surface of the finely powdered inorganic material was used as is without activation, were all poorly cured and could not be used sufficiently as nonflammable heat insulating materials. It was impossible.

[0040]

Effects of the Invention As described above, in the inorganic composition for producing a nonflammable inorganic foam according to the present invention, the inorganic solid component consists of alumina sol and/or silica sol on the surface of an inert or small active finely powdered inorganic material. Since it is coated with an active ingredient, it is possible to stabilize the reactivity of the finely powdered inorganic material and increase its activity, thereby making it possible to produce a sufficiently cured, high-quality inorganic foam. The inorganic foam obtained from the inorganic composition has high compressive strength, has homogeneous cells, has a uniform density, and has an extremely good appearance.
It has the effect of being extremely useful as a nonflammable and non-smoke heat insulating material.

Claims (2)

[Claims] 1. An inorganic composition comprising an aqueous alkali metal silicate solution, an inorganic solid component, a filler, and a blowing agent,
Production of a nonflammable inorganic foam, characterized in that the inorganic solid component is an inert or small active finely powdered inorganic material coated with an active component consisting of at least one of alumina sol and silica sol. Inorganic compositions for use. [Claim 2] The finely powdered inorganic substance as an inorganic solid component is silica sand, alumina, kaolin, calcium carbonate, talc, mica,
2. The at least one substance selected from the group consisting of aluminum hydroxide, glass powder, corundum, or electrostatic precipitator ash generated during the production of mullite, fly ash, calcined kaolin, and calcined bauxite. Inorganic composition for producing nonflammable inorganic foam.