Inorganic binder and inorganic coating material

Abstract

To provide a technology that can suppress the precipitation of needle-like crystals generated in the curing process, i.e., to provide an inorganic binder and an inorganic coating material by the technology.MEANS: An inorganic coating material of the invention is mainly composed of a specific inorganic binder and inorganic fibers, and the content ratio of components in the inorganic binder is within a specific range. The inorganic binder contains alkali silicate, gypsum, inorganic powder containing SiO2 other than cement and alkali silicate, and water, and the ratio (G / M2O) of the mass (G) of gypsum to the mass (M2O) of the contained alkali in terms of oxide is in a specified range. Suitably, the inorganic fiber is rock wool.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an inorganic binder. More specifically, the present invention relates to an inorganic binder that can suppress the formation of needle-like crystals during the curing process. The present invention also relates to an inorganic coating material. More specifically, the present invention relates to an inorganic coating material that can suppress the formation of needle-like crystals during the curing process. [Background technology]

[0002] Spraying materials such as rock wool spraying material, which is made of fibers such as rock wool and a binder such as cement paste, are sprayed onto structural components to impart fire resistance, fire prevention, sound absorption, or thermal insulation properties. Rock wool spraying material, a representative example of such spraying materials, is made of rock wool, cement, and water and is widely used due to its excellent fire resistance and workability (see, for example, Patent Document 1). Cement is an inexpensive and excellent inorganic binder, but because it is produced by decomposing the raw material limestone at high temperatures and then reacting it with silicon dioxide, aluminum oxide, iron oxide, and other raw materials at high temperatures, it generates a large amount of carbon dioxide, a major greenhouse gas, during its production. For this reason, there is a demand for a spraying material that uses an inorganic binder that does not contain cement as its main component, and for an inorganic binder for such a spraying material.

[0003] It has been disclosed that phosphosilicates, alkali silicates (e.g., water glass), geopolymers, colloidal silica, or colloidal alumina can be used as binders for rock wool fibers (rock wool) of a specific composition (see, for example, Patent Document 2).

[0004] Incidentally, there is a technique in which a binder is sprayed onto fibers to join them and form a sprayed material layer, in which the binder is sprayed together with pressurized air (see, for example, Patent Document 3). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-348978 [Patent Document 2] Special Publication No. 2012-532830 [Patent Document 3] Jikko No. 55-054755 Summary of the Invention [Problem to be solved by the invention]

[0006] Various investigations were conducted on a non-cement inorganic binder containing an SiO2-containing inorganic powder other than cement and alkali silicate, which was sprayed together with rock wool to form a sprayed layer (coating layer) made of a rock wool composition. It was discovered that needle-like crystals sometimes precipitated on the surface of the sprayed layer to a degree that could be seen with the naked eye during the curing process. The present invention aims to provide a technology that can suppress the precipitation of needle-like crystals during the curing process, namely, an inorganic binder and an inorganic coating material. [Means for solving the problem]

[0007] The present inventors have found that the above-mentioned problems can be solved by using a specific inorganic binder and inorganic fibers as the main components and setting the content ratio of the components contained in the inorganic binder within a specific range, and have completed the present invention. That is, the present invention provides the following (1) to (4). (1) An inorganic binder containing alkali silicate, gypsum, an SiO2-containing inorganic powder other than cement and alkali silicate, and water, in which the ratio (G / M2O) of the mass of gypsum (G) to the mass (M2O) of the contained alkali oxide is 0.1 to 4.0. (2) The inorganic binder of (1) above, wherein the ratio (G / M2O) of the mass of gypsum (G) to the mass (M2O) of the alkali contained in terms of oxide is 0.2 to 2.0. (3) An inorganic coating material whose main components are the inorganic binder of (1) or (2) above and inorganic fibers. (4) The inorganic coating material according to (3), wherein the inorganic fiber is rock wool. [Effects of the Invention]

[0008] According to the present invention, an inorganic binder is obtained that can suppress the generation and precipitation of needle-like crystals on the surface of a sprayed material layer (coating material layer) containing an inorganic binder that does not contain cement as its main component and inorganic fibers as its main components during the curing process of the sprayed material layer to a degree that can be visually confirmed. According to the present invention, an inorganic coating material is obtained that is primarily composed of an inorganic binder that does not contain cement as its main component and inorganic fibers, and that can suppress the formation and precipitation of needle-shaped crystals on the surface of the sprayed material layer (coating material layer) to an extent that they are visible to the naked eye during the curing process. Furthermore, since the binder and inorganic fibers used in the present invention do not contain cement as a main component, the amount of carbon dioxide emitted during the production of the raw materials is less than when cement is used as the raw material for the binder. DETAILED DESCRIPTION OF THE INVENTION

[0009] The inorganic binder of the present invention is characterized by containing an alkali silicate, gypsum, "an SiO2-containing inorganic powder other than cement and alkali silicate," and water, and having a ratio (G / M2O) of the mass of gypsum (G) to the mass of the contained alkali oxide (M2O) of 0.1 to 4.0. Here, when the content of alkali contained in components other than the alkali silicate is low (2 mass% or less), it is extremely small compared to the mass of alkali in the alkali silicate, and therefore the mass of alkali contained in said components can be ignored.

[0010] As the gypsum used in the present invention, anhydrous gypsum is preferred because it is easy to obtain the fluidity and usable life of the inorganic binder. In addition, the gypsum used may be a powder having a particle size of 0.5 mm or less, and preferably has a Blaine specific surface area of 2000 cm. 2 / g or more is preferred due to its high reactivity, and furthermore, the Blaine specific surface area is 3000 to 20000 cm 2 / g is more preferred.

[0011] If the ratio (G / M2O) of the mass of gypsum (G) to the mass of alkali oxide (M2O) contained in the inorganic binder of the present invention is less than 0.1, the formation and precipitation of needle-like crystals that occur during the curing process of a sprayed material layer (coating material layer) made of a rock wool composition formed by spraying the inorganic binder together with rock wool cannot be sufficiently suppressed. Furthermore, if the G / M2O exceeds 4.0, the fluidity of the inorganic binder decreases or the usable life is too short to form a sprayed material layer (coating material layer) by spraying. A G / M2O of 0.2 to 3.8 is preferred because it facilitates the fluidity and usable life required to form a sprayed material layer (coating material layer) by spraying, and a G / M2O of 0.2 to 2.0 is more preferred because it provides a usable life of 120 minutes or more.

[0012] In the present invention, the amount of gypsum is preferably 0.5 to 40 mass % and more preferably 2 to 20 mass % relative to the mass of the "SiO2-containing inorganic powder other than cement and alkali silicate."

[0013] The alkali silicate used in the present invention is preferably one or more selected from sodium silicate such as sodium metasilicate or sodium orthosilicate, aqueous sodium silicate solutions such as water glass, lithium silicate or an aqueous lithium silicate solution, and potassium silicate or an aqueous potassium silicate solution, and more preferably one or more selected from sodium silicate or an aqueous sodium silicate solution.

[0014] The SiO2-containing inorganic powder other than cement and alkali silicate used in the present invention (hereinafter sometimes referred to as "SiO2-containing inorganic powder") refers to an inorganic powder containing SiO2 as the main chemical composition other than cement and alkali silicate, and preferred examples include blast furnace slag powder, fly ash, metakaolin, silica fume, volcanic ash, igneous rock powder, powder of burned igneous rock, powder of burned sewage sludge slag, and powder of molten slag from municipal waste. The SiO2-containing inorganic powder is preferably an inorganic powder having a Blaine specific surface area of 2000 cm 2 / g or more is preferred because the binder hardens quickly, and more preferably 2500 cm 2 The upper limit of the Blaine specific surface area of the SiO2-containing inorganic powder used in the present invention is 12000 cm2, since this allows the time during which the fluidity of the binder can be maintained to be long. 2 / g or less, and more preferably 10000 cm 2 / g or less.

[0015] The inorganic binder of the present invention contains an alkali silicate, an SiO2-containing inorganic powder other than cement and alkali silicate, and water, and the water content is preferably 50 mass% or more. Here, the water content (C W ) is the mass of water (M W ) to the mass of inorganic binder (M B ) and expressed as a percentage. The mass of water contained in the inorganic binder at this time (M W ) does not need to be taken into consideration when the influence of moisture in the atmosphere is so small that it can be ignored, such as the mass of water contained in SiO2-containing inorganic powder.

[0016] C W (%)=M W ÷M B ×100 (1)

[0017] The water content (C W If the water content (C) is 50% by mass or more, the binder can be sprayed using a spraying device used for spraying rock wool using the semi-dry method without using compressed air to spray the binder, and it can be mixed with the fibers of rock wool or the like to form a homogeneous sprayed material layer. Here, "homogeneous" means that when the fibers used for spraying are clumped (granular) like the rock wool (granular rock wool cotton) used for spraying rock wool, the binder is attached almost evenly to the surface of the fiber clumps, some of which penetrates into the interior of the fiber clumps, and the binder is present between the fiber clumps. W) is more preferably 60% by mass or more, since it is easier to obtain high fluidity of the inorganic binder, and 60 to 96% by mass is even more preferable, and 75 to 90% by mass is most preferable, since the amount of dust generated during spraying is small and dripping (liquid dripping) of the inorganic binder from the sprayed inorganic coating layer is unlikely to occur.

[0018] The inorganic binder of the present invention is used as a binder for spraying fibers. Here, the fibers are not particularly limited as long as they can be sprayed together with the binder, and suitable examples include cotton-like fibers such as rock wool (including slag wool), glass wool, and ceramic wool.

[0019] The inorganic binder of the present invention may contain an alkali hydroxide such as sodium hydroxide, potassium hydroxide, or lithium hydroxide, or an aqueous solution thereof.

[0020] The inorganic binder of the present invention is an inorganic binder containing alkali silicate, "a SiO2-containing inorganic powder other than cement and alkali silicate," and water as its main components, but may also contain other inorganic and organic components. As this other inorganic component, cement may be contained in an amount of up to 10% by mass relative to the mass of the SiO2-containing inorganic powder, and in this case, the cement acts mainly as a stimulant for the SiO2-containing inorganic powder. Because the amount of carbon dioxide generated during the production of raw materials is small, the cement content in the fiber spray binder of the present invention is preferably 5% by mass or less, and even more preferably 2% by mass or less, relative to the mass of the SiO2-containing inorganic powder.

[0021] The inorganic coating material of the present invention is mainly composed of the above-mentioned inorganic binder and inorganic fibers. The inorganic fibers in the present invention are not particularly limited as long as they can be sprayed together with the inorganic binder. For example, cotton-like fibers such as rock wool, glass wool, and ceramic wool are preferred in terms of fire resistance, fire prevention, sound absorption, and heat insulation, and rock wool, glass wool, and ceramic wool are more preferred because they are non-flammable and do not rust, with rock wool being most preferred in terms of stability with the binder. In the present invention, rock wool refers to a material (mineral fiber) produced by rapidly cooling a material mainly composed of rocks or blast furnace slag melted in a melting furnace, and then turning it into fibers. For example, rock wool made from a material mainly composed of blast furnace slag is also included.

[0022] The inorganic coating material (rock wool coating material) of the present invention may contain components other than those mentioned above, such as various cement, mortar or concrete admixtures containing alkali metal salts such as sodium carbonate and sodium sulfate, as well as other components (additives), provided that the effects of the present invention are not impaired.

[0023] The inorganic coating material (rock wool coating material) of the present invention is preferably produced by a spraying method similar to the semi-dry method of rock wool spraying. In this case, the above-mentioned inorganic binder is used instead of the cement paste used in the semi-dry rock wool spraying method, and if the inorganic fiber is other than rock wool, the inorganic fiber is used instead of rock wool. The inorganic fiber (rock wool) is pressurized through a pressure hose and discharged from the outlet of a spray nozzle connected to the pressure hose, and the above-mentioned inorganic binder is sprayed onto it, thereby producing the inorganic coating material of the present invention made of a rock wool composition.

[0024] The inorganic coating material (rock wool coating material) of the present invention can be used as a substitute for a rock wool composition (sprayed rock wool) whose main components are rock wool and cement paste. That is, it can be used as a fire-resistant coating material, a sound-absorbing coating material (sound-absorbing material), or a heat-insulating coating material (heat-insulating material, thermal insulation material). In particular, when the fibers contained are rock wool, glass wool, or ceramic wool, the inorganic coating material of the present invention does not contain a flammable material as a main component, so that by reducing or eliminating the content of flammable materials, it can be made into a non-flammable coating material. [Example]

[0025] [Example 1] An inorganic binder for fiber spraying was prepared using alkali silicate, gypsum, "an SiO2-containing inorganic powder other than cement and alkali silicate," and water in the blending ratios shown in Table 1. The materials used are listed below. "%" in Table 1 means "% by mass."

[0026] <Materials used> (1) Alkali silicate: No. 3 water glass (SiO2: 28.93 mass%, Na2O: 9.34 mass%, H2O: 61.73 mass%), symbol: WG3 (2) SiO2-containing inorganic powder other than cement and alkali silicate: blast furnace slag powder (ground blast furnace slag 4000, Blaine specific surface area: 4130 cm 2 / g), symbol;BSF (3) Gypsum: anhydrous gypsum (particle size: 0.2 mm or less and Blaine specific surface area: 7000 cm 2 / g powder), symbol: GY (4) Water: Sakura City Water Supply

[0027] [Table 1]

[0028] The inorganic binders thus prepared were subjected to the following evaluation tests, and the results are shown in Table 2. <Fluidity test> Immediately after preparation and 120 minutes after preparation, the mixture was stirred with a mixer, and the inorganic binder prepared instead of cement slurry was checked for fluidity sufficient to be sprayed using equipment commonly used for semi-dry spraying of rock wool spray materials. If the inorganic binder had fluidity sufficient to be sprayed, it was evaluated as "good" (symbol: ○), and if it did not have fluidity sufficient to be sprayed, it was evaluated as "poor" (symbol: ×).

[0029] <Spraying test> The prepared inorganic binder was sprayed together with rock wool (granular cotton, manufactured by Pacific Materials Co., Ltd.) from a spray gun (nozzle) using equipment commonly used for semi-dry spraying of rock wool spray materials. The spray gun was sprayed onto the inside of a container (inner dimensions 20 cm x 20 cm x 5 cm) to form an inorganic coating layer consisting of the inorganic coating material (rock wool coating material). This was then cured for one month in a thermostatic chamber at a room temperature of 20°C and a humidity of 60% RH. After that, the surface of the inorganic coating layer was visually inspected, and the absence of acicular crystals was rated as "good" (symbol: ○), and the presence of acicular crystals was rated as "poor" (symbol: ×).

[0030] [Table 2]

[0031] The inorganic binders of formulations No. 2 to No. 8, which are examples of the present invention, were all sprayed in place of cement paste from the cement paste nozzle of a spray gun using equipment commonly used for the semi-dry spraying method of rock wool spraying materials, and the inorganic coating material was formed by merging and mixing with the rock wool sprayed from the spray gun.Even after curing for one month, no formation or precipitation of needle-like crystals was observed.In addition, the dust generated during spraying was less than the dust generated during spraying using a semi-dry spraying method using cement paste.

[0032] In contrast, the inorganic coating material formed in the same manner as the inorganic binders Nos. 2 to 8 using the inorganic binder No. 1, in which the ratio (G / M2O) of the mass of gypsum (G) to the mass of alkali oxide (M2O) contained in the inorganic binder was less than 0.1, showed the formation and precipitation of needle-like crystals even after curing for one month. However, the dust generated when spraying was carried out using the inorganic binder No. 1 was less than the dust generated when spraying was carried out using the semi-dry spraying method using cement paste, as was the case when the inorganic binders Nos. 2 to 8 were used.

[0033] In addition, the inorganic binders of Mixtures No. 2 to No. 6, in which the ratio (G / M2O) of the mass of gypsum (G) to the mass of alkali oxide (M2O) contained in the inorganic binder was 0.2 to 2.0, all had fluidity that allowed the formation of a coating material layer by spraying even after 120 minutes, and were extremely excellent in terms of usable time, securing a usable time of 120 minutes. In contrast, the inorganic binders of Mixtures No. 7 and No. 8 had usable times of 90 and 80 minutes, respectively, which were excellent in terms of usable time of 60 minutes or more, but were inferior to the inorganic binders of Mixtures No. 2 to No. 6. [Industrial Applicability]

[0034] The present invention can be suitably used in inorganic coating materials that impart, for example, fire resistance, fire prevention, sound absorption, heat insulation, or the like.

Claims

1. Alkali silicate, gypsum, cement, and SiO other than alkali silicate ２ Contains an inorganic powder and water, The mass of the contained alkali in terms of oxide (M 2 The ratio of the mass of gypsum (G) to the mass of gypsum (G / M 2 O) is 0.1 to 4.

0.

2. The mass of the contained alkali in terms of oxide (M 2 The ratio of the mass of gypsum (G) to the mass of gypsum (G / M 2 2. The inorganic binder according to claim 1, wherein O) is 0.2 to 2.

0.

3. 3. An inorganic coating material comprising the inorganic binder according to claim 1 or 2 and inorganic fibers as main components.

4. 4. The inorganic coating material according to claim 3, wherein said inorganic fibers are rock wool.

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