JPS63151691A - Manufacture of inorganic heat insulator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a method for manufacturing a nonflammable inorganic heat insulating material used for walls and roofs of buildings such as houses, buildings, and freezer/refrigerator storage units. Regarding.

[Conventional technology] Today, heating and cooling equipment for homes and buildings has become more widespread, and freezers and refrigerators have become larger. There is a need for the development of a heat insulating material that is excellent from the viewpoint of disaster prevention and does not have problems such as occurrence of heat.

In order to meet these demands, an inorganic heat insulating material has been proposed which is obtained by adding an alkali silicate inorganic binder to a granular inorganic foam and bonding and molding the inorganic foam. , such inorganic heat insulating materials are satisfactory in that they are lightweight and have excellent heat insulating properties.
However, there was a problem that the compressive strength, water resistance, and weather resistance were insufficient.

Therefore, in order to solve these problems, we used metallic silicon or its alloy powder and phosphate as a hardening agent for the binder, without sacrificing the lightweight feature.
A patent application to develop and propose a manufacturing method for inorganic insulation materials that improves compressive strength and water resistance, and also shortens the time required for curing compared to conventional methods, thereby increasing productivity. Invention No. 142,428 of 1980).

[Problems to be Solved by the Invention] The present invention is an improvement on the above-mentioned invention proposed previously, and aims to further shorten the reaction time required for curing to improve productivity, and to make the curing reaction more uniform. The purpose of the present invention is to provide a method for manufacturing an inorganic heat insulating material that can uniformize compressive strength and uniform product quality by carrying out the process.

[Means for Solving the Problems] That is, the present invention mixes a granular inorganic foam, an alkaline silicate solution used as a binder, and a curing agent for the binder mainly consisting of metal silicon powder. , a method for producing an inorganic heat insulating material, in which the reaction mixture in the mold is actively heated using a heating means when the obtained reaction mixture is injected into a mold to mold the inorganic heat insulating material. .

The granular inorganic foam used in the present invention includes:
It may be any conventionally known material, but is preferably obsidian, vermiculite, nacre, or pinestone. These inorganic foams can be used alone or as a mixture of two or more. can also be used. The particle size and density of this inorganic foam vary depending on the intended product insulation, type of heat material, application, etc., but are usually 0.5~
A particle size of 7 m and a density of usually 0.1 to 0.25 g/cm3 are used. In addition, especially when lightweight and excellent heat insulation properties are required, the density is 0.1 to 0.16 g/c.
It is preferable to use m3.

Further, as the alkaline silicate solution used as a binder in the present invention, a sodium silicate aqueous solution or a potassium silicate aqueous solution is usually used, but a sodium silicate aqueous solution is preferable from the viewpoint of solubility in water and raw material cost.

As sodium silicate, the molar ratio of SiO2 to Na2O is usually in the range of 2.0 to 3.5, preferably 2.3 to 2.7, and the concentration of its aqueous solution is usually in the range of 35 to 3.5. 42% by weight, preferably 40-42% by weight. Also, regarding the usage amount of this alkaline silicate solution,
Although it varies depending on the concentration, it is usually 30 to 120 parts by weight, preferably 50 to 120 parts by weight, per 10,011 parts of the inorganic foam.
It is 100 parts by weight.

If the amount of the alkaline silicate solution used is less than 30 parts by weight, the bonding force will be small, resulting in a decrease in strength;
If the amount is more than 1 part by weight, the binder will be excessive, causing heat generation and
This results in the binder component flowing out during the dehydration curing reaction stage, resulting in the problem that it does not work effectively. Note that the alkali silicate used in the present invention is not limited to alkali silicate as a single substance, but also includes so-called water glass obtained by heating and melting silicon dioxide and alkali hydroxide, such as sodium metasilicate, sodium orthosilicate,
A mixture of sodium disilicate, sodium tetrasilicate, etc. may be used.

In general, examples of the hardening agent for the binder used in the present invention include metal silicon, ferrosilicon which is an alloy of iron and silicon, and metal silicon powder having properties as metal silicon, such as a mixture of metal silicon and silicon dioxide. These can be used alone or as a mixture of two or more types, but preferably a phosphate is used in combination as another component of the curing agent for the purpose of improving compressive strength and water resistance. The phosphate used for this purpose may be one that reacts with alkali silicate during the curing reaction to produce a binder substance that is poorly water soluble and has excellent thermal stability, and preferably aluminum phosphate, magnesium phosphate, phosphoric acid There are metal phosphates such as iron and zinc phosphate, metal salts of polyphosphoric acid, and metal salts of condensed phosphates in which a metal oxide and phosphorus pentoxide are combined at a predetermined ratio. More preferably, condensed aluminum phosphates are used. It is a representative condensed phosphoric acid metal salt.

The amount of the metal silicon powder used varies depending on the type and concentration of the alkali silicate solution, but is usually 10 to 20 parts by weight, or 13 to 20 parts by weight, per 100 parts by weight of the alkali silicate solution.
It is 15 parts by weight. If the amount of metal silicon powder used is less than 10 parts by weight, the compressive strength and water resistance will not be sufficiently improved, and if it is more than 20 parts by weight, the metal silicon powder will be oxidized and will not work effectively. In addition, the amount of phosphate added for the purpose of improving compressive strength and water resistance is determined by the amount of alkali in the alkaline silicate solution, and varies depending on the type and concentration of the alkaline silicate solution. The amount is usually 2 to 30 parts by weight, preferably 10 to 20 parts by weight. Phosphate usage is 2
If it is less than 1 part by weight, there is no effect of adding this phosphate,
Further, even if the amount is more than 30 parts by weight, no improvement in compressive strength or water resistance is observed.

In the present invention, the alkali silicate, e.g., sodium silicate, used as the binder reacts with metal silicon powder, e.g., metal silicon, used as the hardening agent as follows to produce silicon M (Si02>, and Na20 “S i 02
+H20=NaOH+NaH3!03 NaH8iO3+H20≠ NaOH+H2S i 03 S i +2 N aOH+ n H20−Na2 S
! 03 +2 town ↑ Gradually produces sodium silicate with a high silicate valve.

In the present invention, when manufacturing an inorganic heat insulating material, a granular inorganic foam, an alkaline silicate solution used as a binder, and a hardening agent for this binder are mixed, and the resulting reaction mixture is poured into a mold. The reaction mixture in the mold is actively heated using an appropriate heating means to harden it, and after curing, it is removed from the mold and dried.

The heating temperature applied externally during this curing reaction varies depending on various conditions during molding, such as the composition of the reaction mixture and the type and size of the mold used, but is usually 40 to 150°C. , in order to bring the manufacturing process online, the reaction time until the reaction is completed is 2 to 3.
It is necessary to shorten the time to about 8 minutes, and for this purpose it is preferable to
It is in the range of 0 to 120°C. If the heating temperature is lower than 40°C, the effect of active heating using a heating means will not be sufficiently demonstrated, and if it is higher than 150°C, the temperature rise during the curing reaction will be too rapid, causing the reaction to occur. In addition to making it difficult to manufacture products of uniform quality, the glass bonding caused by the alkali silicate becomes weaker, causing problems such as deterioration of product properties.

The heating means for heating the reaction mixture in the mold may be any conventionally known means, such as a hot air heater installed in a heating chamber and heated with hot air, but preferably high frequency heating. High frequency heating using a furnace or the like is recommended. According to this high-frequency heating, the high-frequency waves pass through things other than metal plates, so by using a mold made of wood or inorganic plate, even if the thickness of the mold is increased, this The reaction mixture in the mold can be heated uniformly, which is particularly advantageous for producing products of uniform quality. In addition, when a lath net is inserted into the inorganic heat insulating material of the product to improve its strength, the lath net can also be heated by supplying electricity.

In general, the molds used in the present invention include:
For example, when molding a board, a frame plate with gas handling holes on at least one side can be used to inject and fill the reaction mixture uniformly, and can be vibrated to ensure uniformity of the resulting product. It is preferable to have a lid with gas handling holes to prevent the reaction mixture from spewing out due to heat generation during the curing reaction.

Additionally, if necessary, reinforcing additives can be added to improve the mechanical strength of manufactured products, such as tensile strength. Examples of reinforcing additives used for this purpose include, for example, steel Examples include mineral fibers such as fibers, glass fibers, and rock wool, and the blending ratio thereof can be appropriately selected depending on the use of the inorganic heat insulating material. In addition, when this reinforcing additive is blended, the amounts of the above-mentioned alkaline silicate solution and curing agent used are:
Considering this reinforcing additive as part of the inorganic foam,
Although it depends on the type of reinforcing additive, a slight increase in the amount is required.

[Function] According to the method of the present invention, a reaction mixture consisting of an inorganic foam, an alkali silicate solution, and a curing agent mainly composed of metal silicon powder is actively heated in a mold using a heating means. The reaction time of the curing reaction can be shortened by increasing the reaction rate, and this reaction time can be controlled by controlling the degree of heating, and the curing reaction is forced to proceed by heating, so that the reaction mixture is completely absorbed. The reaction can be carried out without any unreacted parts remaining and adversely affecting the quality of the product.

[Example] Hereinafter, the method of the present invention will be specifically explained based on Examples and Comparative Examples.

Example 1 Inorganic foam with an average particle diameter of about 2.0 m and a density of 0.13
'j/cm3 obsidian foam 260g, water glass 200g
g, 60 g of ferrosilicon and 20 g of aluminum phosphate
A reaction mixture was prepared by blending and mixing, and this reaction mixture was poured into a wooden box-shaped mold measuring 200 m long x 200 mm wide x 50 m deep with an open top and closed with a lid having many small holes. This lid was fixed, placed in a high frequency heating furnace, and heated to about 100 to 120'C by high frequency heating. Approximately 40 seconds after the start of heating, an intense dehydration reaction begins, and after 50 seconds, this dehydration reaction has almost subsided and the curing reaction is completed, and the inorganic heat insulating board of the product is taken out from the mold.
The grains were completely dehydrated and dried, and no particles were observed to fall off or be missing from the periphery.

The inorganic heat insulating board manufactured in this way was equally divided into 50# test pieces (50# x 50# The compressive strength was measured, and the average value of the compressive strength of the 12 test pieces located at the periphery (peripheral compressive strength) and the average value of the compressive strength of the 4 test pieces located at the center (center compressive strength) The results were as follows: The compressive strength of the test piece at the periphery was within the range of 20.0 to 21, 3KI/CIi, and the average value (compressive strength at the periphery) was 20.0 to 21.
8KI/cri, whereas the compressive strength of the central test piece was within the range of 20.5 to 21.5'j/cri, and the average value (central compressive strength) was 21.2.
The difference was 0.4 KI/cri. The compressive strength was determined by applying pressure to the test piece from the surface direction and determining the pressure value when the test piece began to collapse.

Example 2 An inorganic heat insulating board was produced in the same manner as in Example 1, except that a hot air heater set at 100"C was used as the heating means. Approximately 5 minutes after the start of heating, an intense dehydration reaction began, and approximately After this intense dehydration reaction continued for 1 minute, the dehydration reaction almost subsided after 6 minutes and the curing reaction was completed.In the case of this Example 2, as in the case of Example 1, the molding mold was The inorganic heat insulating board of the product taken out from inside was almost completely dehydrated and dried, and no particles were observed to fall off or be missing around the periphery.

Regarding the obtained inorganic heat insulating board, the peripheral compressive strength and central compressive strength were determined in the same manner as in Example 1 above. As a result, the compressive strength of the peripheral test piece was 18.
The average value (peripheral compressive strength) must be within the range of 0 to 20.5'J/ct/r, and the average value (peripheral compressive strength) is 19°5 K'j/c
m, whereas the compressive strength of the central test piece was within the range of 19.0 to 21, OK'J/cm, and the average value (central compressive strength) was 20°2 K9/cm.
ci, and the difference was 0.6 Kg/cm.

Comparative Example 1 An inorganic heat insulating board was produced in the same manner as in Example 1, except that the reaction was allowed to occur indoors at a temperature of 20° C. without using any h0 heating means. The curing reaction started immediately after preparing the reaction mixture, but by the time the dehydration reaction was completed, 92.
In addition, the inorganic heat insulating board of the product taken out from the mold was not sufficiently dehydrated and required a further drying process, and some particles were found to have fallen off around the periphery. It was done.

Regarding the obtained inorganic heat insulating board, the peripheral compressive strength and central compressive strength were determined in the same manner as in the above example. The result was that the compressive strength of the peripheral test piece was 10.4.
~'16.7, the average value (peripheral compressive strength) within the range of 'j/crA was 14°2 K3/cm, while the compressive strength of the central test piece was 18.
．． 7 to 21, 0 to 3/crA, and the average value (center compressive strength) is 19°4 Kg/cit
t, and the difference was 5.2KI/ctr.

Comparative Example 2 An inorganic fiberboard was produced in the same manner as in Comparative Example 1, except that it was left in a room at a temperature of 30° C. to undergo a curing reaction. It took 56 minutes to complete the dehydration reaction, and this Comparative Example 2
In this case, the inorganic insulation board of the product removed from the mold was insufficiently dehydrated and required a rough drying process, and some particles were observed to have fallen off in some of the surrounding areas. .

Regarding the obtained inorganic heat insulating board, the peripheral compressive strength and central compressive strength were determined in the same manner as in Example 1 above. The result was that the compressive strength of the peripheral test piece was 11.1.
It is within the range of ~16.9 KI/crit, and its average value (peripheral compressive strength) is 14°5! j/cIIi, whereas the compressive strength of the central test piece was 18.
7 to 21, within the range of 0Kg/cIi, the average value (center compressive strength) is 19°8'j/crj, and the difference is 5.3! It was j/ar+.

Example 3 An inorganic fiberboard was produced in the same manner as in Example 1 except that the amount of aluminum phosphate used was 23 to prepare a reaction mixture. A test piece (4
0 m x 40 m x 10 m> was cut out, and the test piece was immersed in boiling water for 15 minutes to perform a boiling test. As a result, no discoloration of the water was observed, and no disintegration of the test piece was observed at all. This revealed that the binder in the test piece did not dissolve into water and had excellent water resistance.

Comparative Example 3 An inorganic fiberboard was produced in the same manner as in Example 3, except that the reaction was allowed to occur in a room at a temperature of 20° C. without using any heating means. A test piece was cut out from the inorganic heat insulating board obtained in the same manner as in Example 3, and a boiling test was conducted.

As a result, the boiling water turned black after about 30 seconds, and the test piece disintegrated after about 2 minutes.

Comparative Example 4 Example 3 above except that aluminum phosphate was not used
An inorganic fiberboard was produced in the same manner. A test piece was cut out from the inorganic heat insulating board obtained in the same manner as in Example 3, and a boiling test was conducted. As a result, the boiling water turned black after about 30 seconds, and the test piece disintegrated into granular suspended matter within one minute.

[Effects of the Invention] According to the method of the present invention, it is possible to significantly shorten the reaction time required for curing when producing an inorganic heat insulating material, thereby improving productivity, and to perform the curing reaction more uniformly. In particular, the compressive strength in the peripheral portion and the center portion can be made uniform, thereby making it possible to make the quality of the product uniform.

Claims (3)

[Claims] (1) Mix granular inorganic foam, an alkaline silicate solution used as a binder, and a curing agent for the binder, which is mainly composed of metal silicon powder, and inject the resulting reaction mixture into a mold. When forming inorganic insulation materials,
A method for producing an inorganic heat insulating material, comprising actively heating the reaction mixture in the mold using a heating means. (2) The method for producing an inorganic heat insulating material according to claim 1, wherein the heating temperature range is from 40 to 150°C. (3) Claim 1 in which the heating means is high frequency heating
A method for producing an inorganic heat insulating material according to item 1 or 2.