JPH0443877B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for manufacturing a nonflammable inorganic heat insulating material used for walls, roofs, etc. of buildings such as houses, buildings, and warehouses for freezing and freezing. [Conventional technology] With the improvement of living standards, heating and cooling of houses and buildings has become popular, and as warehouses for freezing and refrigerated storage are becoming larger, there is a demand for the development of insulation materials with excellent heat insulation properties. For a time, organic products came to be used. However, such organic heat insulating materials have problems from the viewpoint of disaster prevention, such as flammability, smoke-emitting properties, and harmful gas-emitting properties, and their use is gradually being restricted. Therefore, in order to solve these problems such as flammability, smoke generation, and harmful gas generation, we have developed a granular inorganic foam with an inorganic binder such as portland cement or alkali silicate as an insulating material that can be used safely from a disaster prevention perspective. An inorganic heat insulating material has been proposed, which is obtained by adding and bond-molding this inorganic foam. [Problems to be Solved by the Invention] However, if Portland cement is used as an inorganic binder for bonding inorganic foam, it has the advantage of increasing its compressive strength, but The problem arises that the weight of the material increases and the weight reduction is impaired.
Further, when an alkali silicate binder is used, there is no problem in terms of weight reduction, but there is a problem in that the compressive strength, water resistance, and weather resistance are insufficient. [Means for Solving the Problems] The present invention was devised in view of this point of view, and takes advantage of the lightweight feature of the alkali silicate binder, improves compressive strength and water resistance, and improves hardening. The purpose of the present invention is to provide a method for manufacturing an inorganic heat insulating material that can shorten the time required for manufacturing and improve productivity. That is, in the present invention, when producing an inorganic heat insulating material by mixing an alkali silicate solution as a binder with a granular inorganic foam and reinforcing additives blended as necessary, and bonding and molding the mixture, the curing agent for the binder is used. This is a method for producing an inorganic heat insulating material using a combination of metal silicon powder and condensed phosphate. 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 preferably used from the viewpoint of solubility in water and raw material cost. As for sodium silicate, the molar ratio of SiO ₂ and Na ₂ O is usually 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 40 to 2.7.
It is 42% by weight. The amount of alkaline silicate solution used varies depending on its concentration, but
The amount is usually 30 to 120 parts by weight, preferably 50 to 100 parts by weight, per 100 parts by weight of the inorganic foam. If the amount of alkaline silicate solution used is less than 30 parts by weight, the bonding force will be small, resulting in a decrease in strength. If it is more than 120 parts by weight, the binder will be excessive, and the binder will be lost during the exothermic/dehydration curing reaction stage. As a result, the problem arises 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, It may be a mixture of sodium orthosilicate, sodium disilicate, sodium tetrasilicate, and the like. The metal silicon powder, which is one component of the curing agent used in the present invention, is not limited to metal silicon itself, but also includes those that have properties as metal silicon, such as an alloy of iron and silicon. Ferrosilicon, a mixture of metallic silicon and silicon dioxide, etc. can also be used. This metal silicon powder, for example, produces silicon oxide through the following reaction with sodium silicate, and gradually
Sodium silicate with a high molar ratio of SiO ₂ /Na ₂ O, for example, sodium silicate with a high molar ratio (SiO ₂ /Na ₂ O) of about 4.0 to 7.0 is formed. Na ₂ O・SiO ₂ +H ₂ O〓 NaOH＋NaHSiO ₃ NaHSiO ₃ +H ₂ O〓 NaOH＋H ₂ SiO ₃ Si＋2NaOH＋nH ₂ O→ Na ₂ SiO ₃ +2H ₂ ↑ The amount of this metal silicon powder used depends on the type and concentration of the alkaline silicate solution. The amount of metal silicon is usually 10 to 20 parts by weight, preferably 13 to 15 parts by weight, although it varies depending on the case, based on 100 parts by weight of this alkaline silicate solution. If the amount of metal silicon powder used is less than 10 parts by weight, improvements in compressive strength and water resistance will be insufficient, and
Even if the amount exceeds 20 parts by weight, the problem arises that the metal silicon powder is oxidized and does not function effectively. Further, the condensed phosphate used as another component of the curing agent may be one that reacts with an alkali silicate during the curing reaction to produce a binder substance that is poorly water-soluble and has excellent thermal stability. There are polyphosphates, metaphosphates, ultraphosphates, etc., preferably condensed metal phosphates such as condensed aluminum phosphate, condensed magnesium phosphate, condensed iron phosphate, condensed zinc phosphate, etc., and more preferably It is condensed aluminum phosphate. The amount of condensed phosphate used 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, but is usually 2 to 30 parts by weight per 100 parts by weight of the alkaline silicate solution. parts by weight, preferably 10
~20 parts by weight. If the amount of condensed phosphate used is less than 2 parts by weight, the improvement in compressive strength and water resistance is insufficient, and even if it is more than 30 parts by weight, an improvement in compressive strength and water resistance is not observed. do not have. In the present invention, a conventionally known method can be adopted as a molding method when producing an inorganic heat insulating material. For example, the inorganic foam is mixed with metal silicon powder and condensed phosphate as a hardening agent. Next, an alkaline silicate solution as a binder is added to this mixture, mixed, and then poured into a mold of a desired shape, and left at room temperature to harden. After the exothermic/dehydration curing reaction is completed, it is removed from the mold and left to dry. For example, when molding a board, the formwork used is a frame plate with gas vent holes on at least one side, and the mixture is injected and filled while applying vibration to ensure uniformity, and after filling is completed, an exothermic reaction occurs. Place a lid with a gas vent hole to prevent water from blowing out, tighten and leave. When left at room temperature for about 30 minutes, what initially reacted gradually becomes
Gradually, a hardening reaction of dehydration condensation occurs with rapid heat generation and evaporation of water vapor. After this curing reaction is completed, it is removed from the mold and left to dry. In the present invention, examples of reinforcing additives that may be blended as necessary include mineral fibers such as steel fibers, glass fibers, and rock wool. It can be selected as appropriate depending on the purpose and the like. 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, a slight increase is required. [Function] In the present invention, metal silicon powder and condensed phosphate are used together as a hardening agent, so when this hardening agent comes into contact with an alkaline silicate solution as a binder and hardens it, it does not cause oxidation of metal silicon. As a result, an intense exothermic and dehydrating condensation reaction occurs, and it is thought that the condensed phosphate rapidly undergoes a condensation reaction with the activated sodium silicate at the same time as this exothermic reaction, resulting in polymerization. As a result, the amount of silicon oxide in the cured binder increases and SiO ₂ /Na ₂ O
The molar ratio increases to about 4.0 to 7.0, and the condensed phosphate is also efficiently incorporated into the alkali silicate during the exothermic reaction and incorporated into the hardened binder, that is, the glass structure of the alkali silicate. It is believed that this results in the formation of a stable cured product with excellent compressive strength and water resistance, especially water resistance. [Example] Hereinafter, the method of the present invention will be specifically explained based on Examples and Comparative Examples. Example 1 Inorganic foam with average particle diameter of approximately 1 mm and density
Using 120g of 0.12g/ ^cm3 obsidian foam,
100g of 40% sodium silicate aqueous solution, 25g of ferrosilicon, and 0 to 30g of condensed aluminum phosphate (main crystal component name: aluminum dihydrogen tripolyphosphate, manufactured by Hoechst, product name: HB Hardener) having the following properties as a condensed phosphate. and a curing agent, mixed and injected into a 200mm x 200mm x 20mm board mold, left at room temperature for about 30 minutes to cure with heat, removed from the mold, and left to dry for 24 hours. An inorganic foam board was molded. A test piece (40 mm x 40 mm x 20 mm) was cut out from this foam board. [Properties of condensed phosphate used] Appearance: White powder crystal Composition: (Elemental analysis) Al: 9.4%, P: 30.2% Crystal form: (X-ray diffraction analysis) AlPO ₄ : 5-10% Al(PO ₃ ) ₃ : 20-30% AlH ₂ P ₃ O ₁₀・2H ₂ O: 70-80% pH: 2.4 (solid acid) Acid strength: 4.5 meq/g True specific gravity: 2.33 Oil absorption: 28.0 ml/100 g Obtained The test pieces were immersed for 24 hours and boiled in hot water for 15 minutes, and the compressive strength was measured before and after each treatment.
The relationship between the amount of condensed aluminum phosphate added per 100g and compressive strength was determined. The results are shown in Figure 1. The compressive strength was determined by applying pressure from the surface direction of the test piece and determining the pressure value at which the test piece began to collapse. Comparative Example 1 An inorganic foam board was molded in exactly the same manner as in Example 1 except that only ferrosilicon was used as a hardening agent, and a test piece was cut out. The relationship between the amount of ferrosilicon added to 100 g of sodium aqueous solution and compressive strength was determined. The results are shown in Figure 2. Comparative Example 2 Example 1 above except that only the same condensed aluminum phosphate used in Example 1 above was used as the curing agent, and the curing time was 168 hours at room temperature.
An inorganic foam board was molded in exactly the same manner as above, and a test piece was cut out. Regarding the obtained test piece, the relationship between the amount of condensed aluminum phosphate added to 100 g of the sodium silicate aqueous solution and the compressive strength was determined in the same manner as in Example 1. I asked for it. The results are shown in Figure 3. Examples 2 to 5 Inorganic foam with average particle size of about 1.5 mm and density
260 g of pearlite grains of 0.13 g/cm ³ were used, and 40 g of sodium silicate with a molar ratio (SiO ₂ /Na ₂ O) of 2.7 was used.
% aqueous solution, 40 g of metallic silicon powder, and a hardening agent consisting of 10 to 40 g of the same condensed aluminum phosphate as in Example 1 above, and mixed to form a 200 mm x 200 mm x
The mixture was poured into a 40 mm plate molding mold, covered with a lid having gas vent holes, and left to stand at room temperature. After being cured by heat, the mixture was removed from the mold and left to stand for 24 hours, followed by drying to form an inorganic foam board. The molar ratio (SiO ₂ /Na ₂ O) of the cured product of this inorganic foam board was 6.7. In addition, when molding this inorganic foam board, a thermometer was set in the center of the mold for molding the board material to measure the temperature of heat generated during molding, and the molding time required from the start of mixing to the end of curing was measured. The results are shown in Table 1. Next, test pieces (40 mm x 40 mm x 40 mm) were cut out from the obtained inorganic foam board, and these test pieces were immersed in water for 24 hours (immersion treated products) and then soaked in boiling water for 15 minutes in the same manner as in Example 1 above. The compressive strength was measured after the boiling treatment (hot water boiling treated product) and before these treatments (untreated product).
The results are shown in Table 1. Comparative Examples 3 to 6 The condensed aluminum phosphate used in Examples 2 to 5 above was not used, or in place of it, aluminum phosphate (chemical grade manufactured by Wako Pure Chemical Industries, Ltd.) 10 to
Using 30 g, an inorganic foam board was molded in the same manner as in Examples 2 to 5 above, and a test piece was cut out from this inorganic foam board, and the heat generation temperature during molding, molding time, and after immersion in water for 24 hours ( 15
The compressive strength was measured after boiling in hot water for 1 minute (hot water boiling treated product) and before these treatments (untreated product).
The results are shown in Table 1.

[Properties of condensed phosphate used]

A: Condensed aluminum phosphate (Main crystal component name: Aluminum tripolyphosphate, Hoechst product name: HB Hardener S) Appearance: White powder crystal Composition: (Elemental analysis) Al: 11.5%, P: 31.9% Crystal form: ( X-ray diffraction analysis) AlPO ₄ : 10-20% Al(PO ₃ ) ₃ : 50-60% AlH ₂ P ₃ O ₁₀・2H ₂ O: 20-30% pH: 2.3 (solid acid) Acid strength: 2.7 meq /g True specific gravity: 2.38 Oil absorption: 27.5ml/100g B: Condensed aluminum phosphate (Main crystal component name: Aluminum dihydrogen tripolyphosphate, manufactured by Yoneyama Chemical Industry Co., Ltd. Product name: YONEPHOS MAY) Appearance: White powder crystal Composition : (Elemental analysis) Al: 13.4%, P: 30.2% Crystal form: (X-ray diffraction analysis) AlPO ₄ : 30-40% Al(PO ₃ ) ₃ : 10-20% AlH ₂ P ₃ O ₁₀・2H ₂ O: 50-60%

[Table] [Effects of the Invention] According to the present invention, since metal silicon powder and condensed phosphate are used together as a curing agent, the product is more stable than when these metal silicon powder or condensed phosphate are used alone. The compressive strength and water resistance of inorganic insulation materials are significantly improved. Moreover, since an exothermic and dehydrating reaction occurs and the binder is chemically activated, the curing time of the binder during molding can be significantly shortened, and the productivity can be improved.

[Brief explanation of drawings]

Fig. 1 is a graph showing the relationship between the amount of curing agent added and compressive strength in the test piece according to the example of the present invention, and Fig. 2 is a graph showing the relationship between the amount of curing agent added and compressive strength in the test piece according to Comparative Example 1 A graph showing the relationship. FIG. 3 is a graph showing the relationship between the amount of curing agent added and the compressive strength in the test piece according to Comparative Example 2.

Claims (1)

[Scope of Claims] 1. When producing an inorganic heat insulating material by mixing an alkali silicate solution as a binder with a granular inorganic foam and reinforcing additives blended as necessary, and bonding and molding, the curing of the binder is performed. A method for producing an inorganic heat insulating material, characterized by using a metal silicon powder and a condensed phosphate together as an agent. 2. The method for producing an inorganic heat insulating material according to claim 1, wherein the inorganic foam is one or a mixture of two or more selected from the group consisting of obsidian, vermiculite, perlite, and pinestone. 3. The method for producing an inorganic heat insulating material according to claim 1 or 2, wherein the alkaline silicate solution is a sodium silicate solution. 4. The method for producing an inorganic heat insulating material according to any one of claims 1 to 3, wherein the condensed phosphate is condensed aluminum phosphate. 5. The method for producing an inorganic heat insulating material according to any one of claims 1 to 4, wherein the blending ratio of condensed phosphate in the binder is 2 to 30 parts by weight per 100 parts by weight of the alkali silicate solution. .