JPH0585858A - Composition for inorganic foam - Google Patents

Abstract

PURPOSE:To provide a composition for inorganic foam capable of forming inorganic foam having open cells, given density and strength, good appearance, extremely excellent qualities useful as sound absorbing material and filter. CONSTITUTION:A composition for inorganic foam consists of 100 pts.wt. main material comprising 20-65 pts.wt. aqueous solution of alkali metal silicate, 15-60 pts.wt. inorganic solid component and 0-65 pts.wt. filler, 0.001-5 pts.wt. anionic surfactant and 2-30 pts.wt. blowing agent.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an inorganic foam which is useful as a non-combustible and smokeless building material useful as, for example, a sound absorbing material and a filter, and which can form an inorganic foam having open cells. The present invention relates to a foam composition.

[0002]

2. Description of the Related Art Conventionally, an inorganic foam having closed cells made of a water-containing curable inorganic molding material has been already known.

That is, a conventional inorganic foam is made of a composition for an inorganic foam, which comprises an aqueous alkali metal silicate solution, an inorganic solid component, a filler and a foaming agent, and has a light weight and a low thermal conductivity. However, it has been used as a building material such as a heat insulating material.

[0004]

However, all the inorganic foams produced according to the known state of the art have closed cells, and are therefore used for specific applications, especially continuous materials such as sound absorbing materials and filters. There is a problem in that it cannot be used in applications that require air bubbles.

The inventors of the present invention have conducted extensive studies in order to solve the above problems, and as a result, by mixing an anionic surfactant in a predetermined ratio with the main material of the inorganic foam, An inorganic foam having open cells can be obtained, and the obtained inorganic foam does not have a large change in density as compared with the inorganic foam having closed cells, and has no decrease in strength, and has a good appearance, They have found that they have excellent quality, and completed the present invention.

An object of the present invention is to form an inorganic foam which has open cells of a predetermined shape, has a required density and strength, and has a good appearance, and which is useful as a sound absorbing material, a filter and the like. It is an attempt to provide a composition for an inorganic foam, which is capable.

[0007]

In order to achieve the above-mentioned object, the present invention provides an alkali metal silicate aqueous solution 20-6.
5 parts by weight, 15 to 60 parts by weight of inorganic solid component, and 100 parts by weight of main material consisting of 0 to 65 parts by weight of filler, 0.001 to 5 parts by weight of anionic surfactant, and 2 to 30 of foaming agent.
The gist is a composition for an inorganic foam comprising 1 part by weight.

Here, as the alkali metal silicate aqueous solution, an aqueous solution of potassium silicate, sodium silicate, or a mixture thereof is used.

The composition of such an aqueous solution is SiO ₂ and K
₂ O, SiO ₂ and Na ₂ O, or SiO ₂ and K ₂ O +
Na ₂ O having a molar ratio of 1.0 to 3.0
And the concentration of the aqueous solution is preferably in the range of 30 to 60%.

As the above inorganic solid components, amorphous SiO _{2 of 2 to} 98% by weight and Al ₂ O ₃ 98 to ₂ % by weight are used.
An oxidation mixture containing is used.

As such an oxidizing mixture, for example, dust generated during the production of metakaolin, corundum or mullite, crushed bauxite, fly ash, etc. can be used. Further, silica fume (pyrogenic silica) or the like may be mixed and used.

For example, the corundum production furnace dust contains 50% by weight or more of an oxidation mixture of amorphous SiO _{2 of} 20 to 80% by weight and Al ₂ O _{3 of} 80 to 20% by weight, and the balance is Fe ₂ O ₃ , TiO _{2 and the} like.

As the above-mentioned filler, pulverized or finely divided inorganic substances such as rock powder, basalt, mica, silica sand, glass powder, alumina, aluminum hydroxide, talc, calcium carbonate, kaolin and other clays, fiber materials Various other inert or water-insoluble minerals can be used. These fillers are appropriately selected according to the use of the inorganic foam, and are used alone or as a mixture.

As the foaming agent, so-called sodium perborate, hydrogen peroxide solution, or inactivated or non-inactivated form of aluminum powder is advantageous. The amount of the foaming agent is appropriately determined depending on the density of the foam, the strength of the foam to be obtained, and the type of the foaming agent.

Examples of the anionic surfactant include alkali metal salts of higher fatty acids represented by the formula: R-COOM, alkyl sulfate salts represented by the formula: R-OSO ₃ M, formula: R-aryl-SO ₃ M. Examples thereof include alkylaryl sulfonate salts and the like.

In the above formula, R is an alkyl group, preferably C
_{5 represents a} C ₃₀ -C ₃₀ alkyl group, M represents an alkali metal atom, and aryl represents an aromatic group such as benzene, toluene and naphthalene.

Specific examples of these anionic surfactants include sodium stearate, sodium oleate, potassium oleate, potassium palmitate, sodium laurylbenzenesulfonate and sodium lauryl sulfate.

The above-mentioned anionic surfactant can obtain a sufficient effect if it is used alone, but it goes without saying that a plurality of surfactants are mixed and used.

The anionic surfactant is powder,
It may be added in any form such as liquid or aqueous solution.

The blending ratio of the composition for inorganic foam according to the present invention is 20 to 65 parts by weight of an aqueous alkali metal silicate solution,
Inorganic solid component 15-60 parts by weight, and filler 0-65
Anionic surfactant 0.001 to 5 parts by weight, preferably 0.005 to 100 parts by weight based on 100 parts by weight of the main material.
1 part by weight and 2 to 30 parts by weight of a foaming agent.

Here, the mixing ratio of the alkali metal silicate aqueous solution, which is the main material of the inorganic foam, the inorganic solid component and the filler is appropriately determined depending on the use and density of the inorganic foam.

In the present invention, the anionic surfactant is contained in an amount of 0.001 to 5 parts by weight, preferably 0.00, relative to 100 parts by weight of the main material of the inorganic foam.
It is mixed in a ratio of 5 to 1 part by weight.

Here, if the compounding ratio of the anionic surfactant is less than 0.001 part by weight, a sufficient effect cannot be obtained and an open-cell foam cannot be obtained. That is, it becomes a closed cell foam.

Further, the compounding ratio of the anionic surfactant is 5
If it exceeds the weight part, the shape of the bubbles in the molded product becomes non-uniform,
It is not preferable because the strength is reduced.

That is, by changing the amount of the anionic surfactant added within the range of 0.001 to 5 parts by weight, the open cell rate and the performances associated with the open cells (sound absorption rate, ventilation resistance, etc.) can be improved. , Can be arbitrarily adjusted within a certain range. Particularly, in terms of uniformity and appearance, the range of 0.005 to 1 part by weight is preferable.

From the composition for an inorganic foam according to the present invention,
In order to produce an inorganic foam having open cells, first, a solid component in the composition, which is an inorganic solid component, a filler, and an anionic surfactant (if solid), and, if necessary, an appropriate amount of A pigment is added and mixed, and then an aqueous solution of an alkali metal silicate, which is a liquid component, is added thereto, and the mixture is kneaded until the solid component is sufficiently dispersed. When the anionic surfactant is in a liquid state, it is added together at the step of adding the alkali metal silicate aqueous solution, and further mixed sufficiently. After that, a foaming agent is added and kneading is performed until it is sufficiently dispersed.

The thus obtained raw material kneaded product for inorganic foam is poured into a predetermined mold and heated from room temperature to 100 ° C. for 1 to 4 hours to obtain an inorganic foam having open cells of a predetermined shape. To form.

[0028]

According to the above-mentioned composition for an inorganic foam, the anionic surfactant is contained in a predetermined ratio with respect to the main material of the inorganic foam, which comprises the aqueous alkali metal silicate solution, the inorganic solid component, and the filler, and the foaming agent. By blending in, an inorganic foam having open cells of a predetermined shape can be obtained, and the obtained inorganic foam does not have a large change in density as compared with an inorganic foam having closed cells, and has reduced strength. There is no. In addition, the inorganic foam has a uniform shape of open cells, a good appearance, and excellent quality.

[0029]

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

Examples 1 to 7 K ₂ O 15.3% by weight, Na ₂ O 7.7% by weight, S
Aqueous alkali metal silicate solution (A) having a composition of 24.9% by weight of iO _{2 and} 52.1% by weight of H ₂ O, or K ₂
O is 21.9% by weight, SiO ₂ is 25.2% by weight, H ₂
An alkali metal silicate aqueous solution (B) having a composition of O of 52.9% by weight, one or two kinds of corundum furnace dust, metakaolin, fly ash and silica fume as an inorganic solid component, and talc and mica as a filler. Potassium oleate (Examples 1 to 5), sodium lauryl sulfate (Example 6), and sodium laurylbenzene sulfonate (Example 7) as anionic surfactants relative to 100 parts by weight of the main material consisting of 10 as a foaming agent
A hydrogen peroxide solution having a concentration of wt% was prepared for each of the examples at the compounding ratio shown in Table 1.

Here, a filter for corundum production
Dust is 50% by weight of amorphous SiO ₂ and Al ₂ O ₃
25% by weight and the balance Fe ₂ O ₃ and TiO _{2 and the} like.

First, since potassium oleate (Examples 1 to 5) and sodium lauryl sulfate (Example 6) are in the form of powder, they are thoroughly mixed with the inorganic solid component and the filler in a container of 1000 cc. The mixture was kneaded, and then an alkali metal silicate aqueous solution was added thereto and kneaded sufficiently. Since sodium laurylbenzene sulfonate (Example 7) is in a paste form, it was added together at the stage of adding the alkali metal silicate aqueous solution and kneaded until the solid components were sufficiently dispersed. A hand mixer was used for mixing and kneading. Then, a foaming agent was added and the mixture was kneaded quickly. The foaming is usually completed in 1 to 10 minutes, and after visually confirming that the expansion of the composition in the container has stopped, the container is sealed and placed in an oven at 50 ° C. for 1 to 3 hours. This allowed the component to cure.

After the completion of curing, the formed inorganic foam was cooled to room temperature in the container and taken out from the container. The obtained inorganic foam was cut into a size of 50 mm × 50 mm × 50 mm with a band saw, sufficiently dried in an oven at 50 ° C., and then the density was measured.

Next, the open cell ratio of the inorganic foam was determined by AS
It was measured by the C method of TM D2856.

Further, visually observing the appearance of the molded article,
Those with uniform air bubbles were evaluated as good, and those with no air bubbles were evaluated as bad. The compressive strength was then measured, and the results are summarized in Table 1.

Comparative Examples 1 and 2 These Comparative Examples are almost the same as the case of the composition for an inorganic foam of Example 1 above, except that the first difference in Comparative Example 1 is the anionic surfactant. The amount of potassium oleate added as the amount is less than the range of the present invention.
0005 parts by weight, and in Comparative Example 2, the amount of potassium oleate added was 10.0 parts by weight, which is higher than the range of the present invention.

The inorganic foam compositions of these comparative examples were molded in the same manner as in Example 1 above.

With respect to the thus obtained inorganic foam, the density, the open cell ratio and the compression strength were measured, and the appearance was observed in the same manner. The obtained results are also shown in Table 1.

[0039]

[Table 1]

As is clear from the results of Table 1 above, according to the compositions for inorganic foams of Examples 1 to 7 of the present invention, inorganic foams comprising an alkali metal silicate aqueous solution, an inorganic solid component, and a filler. Since the anionic surfactant is mixed at a predetermined ratio with the main material of the body and the foaming agent, an inorganic foam having open cells can be obtained, and the obtained inorganic foam has closed cells. There is no great change in the density as compared with the inorganic foam and the strength is not extremely lowered. The inorganic foam had a uniform shape of open cells and a good appearance.

On the other hand, in Comparative Example 1 in which the addition amount of the anionic surfactant, potassium oleate, was 0.0005 parts by weight, which was less than the range of the present invention, an inorganic foam having only closed cells was obtained. Was given. Further, in Comparative Example 1 in which the amount of potassium oleate added was 10.0 parts by weight, which is larger than the range of the present invention, the bubbles were not uniform in appearance, and the strength was higher than those in Examples 1 to 3. It dropped extremely.

[0042]

The composition for an inorganic foam according to the present invention comprises:
As described above, 20 to 65 parts by weight of the alkali metal silicate aqueous solution, 15 to 60 parts by weight of the inorganic solid component, and the filler 0
To 65 parts by weight of the main material, 0.001 to 5 parts by weight of an anionic surfactant, and 2 to 30 parts by weight of a foaming agent. For example, an inorganic foam having open cells of a predetermined shape can be obtained, and the obtained inorganic foam has a required density and strength, and has a large change in density as compared with an inorganic foam having closed cells. And there is no reduction in strength. In addition, the inorganic foam has an effect that the shape of the open cells is uniform, the appearance is good, and the quality is very excellent, and that it can be advantageously used for applications such as a sound absorbing material and a filter.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location C04B 22:00 2102-4G 24:04) 2102-4G

Claims (1)

[Claims] 1. An alkali metal silicate aqueous solution 20 to 65 parts by weight, an inorganic solid component 15 to 60 parts by weight, and a filler 0.
A composition for an inorganic foam, which comprises 100 parts by weight of a main material consisting of ˜65 parts by weight, 0.001 to 5 parts by weight of anionic surfactant, and 2 to 30 parts by weight of a foaming agent.