JPH0455151B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for manufacturing a non-combustible inorganic heat insulating material used for walls and roofs of buildings such as houses, buildings, and warehouses for freezing and refrigerated storage. .

[Conventional technology]

Nowadays, heating and cooling equipment for homes and buildings is becoming more widespread, and freezing and refrigerated warehouses are becoming larger.In addition to being lightweight and having excellent insulation properties, they also have problems such as flammability, smoke generation, and harmful gas generation. Therefore, there is a need for the development of superior thermal insulation materials from a disaster prevention perspective.

In response to such requests,
An inorganic heat insulating material obtained by adding an alkali silicate inorganic binder to a granular inorganic foam and bonding and molding this inorganic foam has been proposed, but such an inorganic heat insulating material is lightweight and Although it was satisfactory in terms of excellent heat insulation properties, there were problems in that it was insufficient in terms of compressive strength, water resistance, and weather resistance.

Therefore, as a solution to these problems, a powder of metal silicon or its alloy and phosphate are used as a hardening agent for the binder, and the compressive strength and water resistance are improved without sacrificing the lightweight feature. Furthermore, we have developed and proposed a manufacturing method for inorganic heat insulating materials that can shorten the time required for curing and improve productivity compared to conventional methods (Japanese Patent Application No. 142,428/1986).

[Problem that the invention seeks to solve]

The present invention is an improvement on the above-mentioned invention proposed earlier, and aims to improve productivity by further shortening the reaction time required for curing, and in particular, uniformizes compressive strength by performing the curing reaction more uniformly. The present invention provides a method for manufacturing an inorganic heat insulating material that can achieve uniform product quality.

[Means for solving problems]

That is, the present invention provides 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 and phosphate are mixed, and the resulting reaction mixture is poured into a mold to form an inorganic heat insulating material. In this method, the reaction mixture in the mold is actively heated to a temperature of 40 to 150° C. using a heating means.

The granular inorganic foam used in the present invention may be any conventionally known material, but is preferably obsidian, vermiculite, nacre, or pinestone, and these inorganic foams are one of them. In addition to being able to use the seeds alone, they can also be used as a mixture of two or more types. The particle size and density of this inorganic foam vary depending on the type of product insulation material and its use, but it is usually 0.5 to 7 mm.
particle size and density usually between 0.1 and 0.25 g/cm ³ are used. Moreover, when a lightweight material with excellent heat insulation properties is particularly required, it is preferable to use one with a density of 0.1 to 0.16 g/cm ³ .

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 SiO ₂ to Na ₂ O is usually in the range of 2.0 to 3.5, preferably 2.3 to 2.7, and the concentration of the aqueous solution is usually 35 to 42% by weight, preferably is 40-42% by weight. In addition, the amount of this alkaline silicate solution to be used varies depending on its concentration, but for 100 parts by weight of the inorganic foam,
It is usually 30 to 120 parts by weight, preferably 50 to 100 parts by weight. If the amount of alkaline silicate solution used is less than 30 parts by weight, there will be a problem of low bonding strength and reduced strength.If it is more than 120 parts by weight, the binder will be excessive and the binder will be removed during the heat generation and dehydration curing reaction stage. As a result, the problem arises that it does not work effectively. 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, sodium metasilicate, ortho It may be a mixture of sodium silicate, sodium disilicate, sodium tetrasilicate, etc.

Further, as the hardening agent for the binder used in the present invention, for example, metal silicon powder having properties as metal silicon, such as metal silicon, ferrosilicon which is an alloy of iron and silicon, and a mixture of metal silicon and silicon dioxide, etc. They may be used alone or as a mixture of two or more, and phosphates may be used in combination for the purpose of improving compressive strength and water resistance. Phosphates used for this purpose may be those that react with alkali silicates during the curing reaction to produce binder substances that are poorly water soluble and have excellent thermal stability, and are preferably aluminum phosphate, magnesium phosphate, or iron phosphate. , metal phosphates such as zinc phosphate, metal salts of polyphosphoric acid, and metal salts of condensed phosphates in which a metal oxide and phosphorus pentoxide are combined in a predetermined ratio, with condensed aluminum phosphate being more preferred. It is a 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, preferably 13 to 15 parts by weight, based on 100 parts by weight of the alkali silicate solution. If the amount of metal silicon powder used is less than 10 parts by weight, the compressive strength and water resistance will be insufficiently 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 also 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 per 100 parts by weight. If the amount of phosphate used is less than 2 parts by weight, there is no effect of adding this phosphate, and if it 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 the metal silicon powder, e.g., metal silicon, used as the curing agent as follows to produce silicic acid (SiO ₂ ), and Na ₂ O・SiO ₂ +H ₂ ONaOH+NaHSiO ₃ NaHSiO ₃ +H ₂ ONaOH+H ₂ SiO ₃ Si+2HaOH+nH ₂ O→ Na ₂ SiO ₃ +2H ₂ ↑ This sodium silicate with a high silicic acid content is gradually produced.

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 for external heating during this curing reaction varies depending on various conditions during molding, such as the formulation of the reaction mixture and the type and size of the mold used, but is usually 40 to 150°C.
Therefore, in order to bring the manufacturing process online, it is necessary to shorten the reaction time to about 2 to 3 minutes, and for this purpose, the temperature is preferably 80 to 120°C.
is within the range of If the heating temperature is lower than 40°C, the effect of active heating using a heating means will not be fully demonstrated, and if it is higher than 150°C, the temperature rise during the curing reaction will be too rapid and the reaction will not occur. In addition to making it difficult to manufacture products of uniform quality, the glass bond caused by the alkaline silicate solution becomes weaker, causing a problem in that the physical properties of the product deteriorate.

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 etc. 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.

Furthermore, in the present invention, when molding a board, for example, the mold used has a frame plate having gas vent holes on at least one side, and the reaction mixture can be uniformly injected and filled to improve the uniformity of the resulting product. It is preferable to have a lid that can be vibrated to ensure the temperature is maintained, and has a gas vent hole to prevent the reaction mixture from spewing out due to heat generated during the curing reaction after filling is completed.

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 fiber, glass fiber, 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 amount of the above-mentioned alkaline silicate solution and curing agent to be used will vary depending on the type of reinforcing additive, considering this reinforcing additive as a part of the inorganic foam. However, it is necessary to increase the amount of Wakachi.

[Effect]

According to the method of the present invention, a reaction mixture consisting of an inorganic foam, an alkali silicate solution, a metal silicon powder, and a curing agent mainly composed of phosphates is heated in a mold to a temperature of 40 to 150°C using a heating means. Since the curing reaction speed is increased by heating, the reaction time can be shortened, and the reaction time can be controlled by controlling the degree of heating, and the curing reaction can be forced to proceed by heating. Therefore, the reaction mixture can be completely reacted, and unreacted portions will not remain and adversely affect the quality of the product.

〔Example〕

The method of the present invention will be specifically explained below based on Examples and Comparative Examples.

Example 1 Inorganic foam with average particle diameter of approximately 2.0 mm and density
0.13g/ ^cm3 obsidian foam 260g, water glass 200g,
A reaction mixture was prepared by blending and mixing 60 g of ferrosilicon and 20 g of aluminum phosphate, and this reaction mixture was poured into a wooden box-shaped mold with an opening on the top and measuring 200 mm long x 200 mm wide x 50 mm deep. The lid was closed and fixed with a lid having small holes, and the lid was 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 complete, and the inorganic heat insulating board of the product taken out from the mold has been almost completely dehydrated and dried. Furthermore, no particles were observed to fall off or be missing in the peripheral areas.

The inorganic heat insulating board manufactured in this way was divided into 16 test pieces (50 mm x 50 mm x 50 mm) by dividing it into equal pieces of 50 mm in length and width, and the compressive strength of each test piece was measured. Measure 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). I compared it. The results show that the pressure cord strength of the peripheral test piece is 20.0 ~
The average value (peripheral compressive strength) was 20.8 Kg/cm ² within the range of 21.3 Kg/cm ² , whereas the compressive strength of the central test piece was 20.5 to 21.5 Kg/cm ²
The average value within the range (center compressive strength)
was 21.2Kg/cm ² , and the difference was 0.4Kg/cm ² . The compressive strength was determined by applying pressure to the test piece from the surface direction and determining the pressure value at which the test piece began to collapse.

Example 2 An inorganic heat insulating board was manufactured in the same manner as in Example 1 above, except that a hot air heater set at 100° C. was used as the heating means. An intense dehydration reaction started about 5 minutes after the start of heating, continued for about 1 minute, and then 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 above, the inorganic heat insulating board of the product taken out from the mold was almost completely dehydrated and dried, and particles in the peripheral area were removed. No omissions or omissions were observed.

Regarding the obtained inorganic heat insulating board, the above Example 1
The peripheral compressive strength and central compressive strength were determined in the same manner as in the case of . The results showed that the compressive strength of the test piece at the periphery was within the range of 18.0 to 20.5 Kg/ ^cm2 , and the average value (compressive strength at the periphery) was 19.6 Kg/ ^cm2 , while that of the test piece at the center was 19.6Kg/cm2. The compressive strength of the test piece was within the range of 19.0 to 21.0 Kg/cm ² , and the average value (center compressive strength) was 20.2 Kg/cm ² , with a difference of 0.6 Kg/cm ² .

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 in a room at a temperature of 20° C. without using any heating means. The curing reaction started immediately after the reaction mixture was prepared, but it took 92 minutes to complete the dehydration reaction, and the inorganic heat insulating board of the product removed from the mold was insufficiently dehydrated and dried. A further drying step was required, and some particles were observed to have fallen off at the periphery.

Regarding the obtained inorganic heat insulating board, the above Example 1
The peripheral compressive strength and central compressive strength were determined in the same manner as in the case of . The results showed that the compressive strength of the test piece at the periphery ranged from 10.4 to 16.7 Kg/cm ² and the average value (peripheral compressive strength) was 14.2 Kg/cm ² . The compressive strength of the test piece was within the range of 18.7 to 21.0 Kg/cm ² , and the average value (center compressive strength) was 19.4 Kg/cm ² , with a difference of 5.2 Kg/cm ² .

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 for the dehydration reaction to complete, and in the case of Comparative Example 2 as well, the inorganic heat insulating board of the product taken out of the mold was insufficiently dehydrated and dried, and a further drying step was required. , Particles were observed to fall off in a part of the periphery.

Regarding the obtained inorganic heat insulating board, the above Example 1
The peripheral compressive strength and central compressive strength were determined in the same manner as in the case of . The results showed that the compressive strength of the test piece in the peripheral part was within the range of 11.1 to 16.9 Kg/cm ² and the average value (peripheral compressive strength) was 14.5 Kg/cm ² , whereas that of the central part was 14.5 Kg/cm 2 . The compressive strength of the test piece was within the range of 18.7 to 21.0 Kg/cm ² , and the average value (center compressive strength) was 19.8 Kg/cm ² , with a difference of 5.3 Kg/cm ² .

Example 3 An inorganic fiberboard was produced in the same manner as in Example 1, except that the amount of aluminum phosphate used was 2 g to prepare the reaction mixture. A test piece (40 mm x 40 mm x 10 mm) was cut out from the obtained inorganic heat insulating board, and a boiling test was conducted by immersing this test piece in boiling water for 15 minutes. 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 indoors 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 An inorganic fiberboard was produced in the same manner as in Example 3 above, except that aluminum phosphate was not used. 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 floating particles within one minute.

〔Effect of the invention〕

According to the method of the present invention, it is possible to further shorten the reaction time required for curing when producing an inorganic heat insulating material, thereby improving productivity, and the curing reaction can be carried out more uniformly. It is possible to equalize the compressive strength at the periphery and center, thereby achieving uniform product quality.

Claims (1)

[Claims] 1. Mix granular inorganic foam, an alkaline silicate solution used as a binder, and a curing agent for the binder mainly composed of metal silicon and phosphate, and inject the resulting reaction mixture into a mold. A method for producing an inorganic heat insulating material, which comprises actively heating the reaction mixture in the mold to a temperature of 40 to 150° C. using a heating means when molding the inorganic heat insulating material.