JP2722390B2 - Fireproof coating - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a fire-resistant coating material for construction, in particular, which is hardened by spraying as a kneaded material on the surface of a steel structure.

[Prior Art] As a fire-resistant coating material, a sprayed fire-resistant coating material using asbestos, rock wool, vermiculite or the like has been conventionally used, but each has problems in pollution, appearance, weather resistance and the like. .

JP-A-61-77687 discloses a refractory composition containing a hydraulic cement, a lightweight aggregate and a substance having a high degree of hydration, which is mixed with water to form a sprayable refractory coating material. used.

[Problems to be Solved by the Invention] However, when the refractory coating material containing the hydraulic cement is sprayed with the kneaded material on the base material, irregularities are easily generated on the sprayed surface, and the thickness is uneven, and However, there is a problem that the adhesiveness is not always sufficient, and the adhesive strength of the coating layer is reduced due to drying shrinkage after spray curing.

An object of the present invention is to provide a refractory coating material that is sprayed uniformly, has excellent adhesion, and has a small decrease in adhesive strength after curing and drying.

Means for Solving the Problems The present inventors have found that the shrinkage after spray drying is due to the drying shrinkage of hydraulic cement, and the adhesiveness is improved by using a binder instead of the binder. And a refractory coating material with high adhesive strength and excellent adhesive strength was obtained.

That is, according to the present invention, 0.1 to 1.0 parts by weight of a water-soluble resin and 100 parts by weight of a base material composed of 2.5 to 12% by weight of cement, 5 to 30% by weight of lightweight aggregate, and 58 to 92.5% by weight of a heat absorbing substance are used. A refractory coating agent comprising 1 to 10 parts by weight of a resin admixture.

(1) Cement Ordinary, early-strength and other portland cements, water-hardening cements such as alumina cement, and various types of mixed cements are used. Usually, ordinary portland cements are used.

The content of cement as a base material is 2.5 to 12% by weight. If the content is less than 2.5% by weight, the ratio of cement to the whole material is reduced, the function as a binder is insufficient, and the mechanical strength of the hardened coating layer is insufficient. On the other hand, if the content exceeds 12% by weight, the adhesive strength of the cement itself increases and the adhesive strength after curing is sufficient, but the specific gravity of the kneaded material used for coating increases, resulting in dripping when spraying. Spraying workability such as a decrease in blow thickness and a decrease in vertical pumping distance during pumping is reduced. Further, the shrinkage due to the dry hardening of the cement is large due to the dry hardening after spraying, and the coating layer is easily cracked.

(2) Lightweight aggregate Lightweight aggregate usually mixed with cement, for example, expanded perlite, expanded vermiculite, expanded shale, pumice, shirasu balloon and the like. These may be used as a mixture. Among them, expanded vermiculite has good scattering properties at the time of spraying the kneaded material, and is preferably used alone or as a mixture with expanded perlite.

The amount of the lightweight aggregate is 5 to 30% by weight in the base material, preferably
10 to 25% by weight. If the amount is less than the above range, the specific gravity of the coating hardened layer increases, and the amount of coating material used per unit area increases to obtain the same fire resistance performance. Also,
Adhesion after spraying is also reduced. If the content exceeds 30% by weight, the mechanical strength of the cured coating layer is reduced, and the adhesion and fire resistance are also reduced.

(3) Endothermic substance The endothermic substance used in the present invention is a substance that is decomposed or dehydrated by heating and consumes added heat, and is a hydrate,
Solid inorganic hydrous compounds such as hydroxides are used. Examples of such materials include aluminum hydroxide, gibbsite, boehmite, aluminum hydroxide hydrates such as diaspore, chabazite, zeolitic minerals such as mordenite,
Examples include hydrous aluminum silicates such as allophane, halloysite, and unexpanded vermiculite; magnesium-based hydrous silicates such as attapulgite; and hydrated sulfates such as ettringite. Among them, aluminum hydroxide is preferably used.

Since the endothermic substance greatly affects the fire resistance of the coating layer, the larger the blending amount, the more effective. However, too large a proportion relatively decreases the proportion of cement.

The compounding amount of the heat absorbing substance in the present invention is in the range of 58 to 92.5% by weight. When the amount is less than 58% by weight, the required fire resistance cannot be obtained, and when the amount exceeds 92.5% by weight, the mechanical strength and adhesion of the coating layer decrease because the proportion of cement decreases.

(4) Water-soluble resin The refractory coating material of the present invention, when sprayed with only the above-described base material composition, is brought into close contact with the sprayed surface, particularly the steel material surface,
Insufficient viscosity for uniform adhesion. The water-soluble resin imparts an appropriate viscosity to the freshly kneaded coating material kneaded with water, has an action of uniformly spraying the sprayed surface to the entire surface and making it adhere to the entire surface, and also maintains the water retention of the kneaded coating material. It improves the operability of spraying by preventing material separation of the kneaded material. It also prevents cracks after curing of the coating layer and improves the properties of the cured coating layer.

Examples of such a water-soluble resin include methyl cellulose,
Polyvinyl alcohol and the like can be mentioned.

The compounding amount of the water-soluble resin in the refractory coating material of the present invention is 0.1 to 1.0 part by weight, preferably 0.15 to 0.5 part by weight, based on 100 parts by weight of the base material composed of the cement, the lightweight aggregate and the endothermic substance. If the amount is less than 0.1 part by weight, no effect is obtained, and the adhesion of the kneaded material is poor. If added in excess of 1.0 part by weight, the viscosity will be too high and the workability of spraying will decrease, and if the viscosity is reduced to a level suitable for work, the base material concentration will decrease and spraying per unit area As a result, the base material is dispersed due to the surface active effect of the water-soluble resin, so that the mechanical strength of the coating layer after drying and curing is reduced.

(5) Synthetic resin-based admixture The synthetic resin-based admixture used in the present invention is generally a synthetic resin dispersion of fine particles that forms a suspension and dispersion state in water, and has an average particle diameter of 0.05 to 100 μm, preferably 0.1 ~
70 μm solid powder or emulsion or latex. This admixture can be previously mixed with the base material if it is a powder, but in the case of a latex or emulsion, it is added and mixed when preparing a kneaded product for spraying.

This synthetic resin-based admixture increases the strength of the cured product when the sprayed coating material is dried and cured, and also enhances the adhesion of the cured product to the spray surface.

Examples of the resin used for such an admixture include an acrylic polymer, an acrylic / styrene copolymer, and an ethylene / styrene copolymer.
Examples include vinyl acetate copolymer (EVA), styrene / butadiene copolymer rubber (SBR), ethylene / vinyl acetate / vinyl versatate (VeoVA) copolymer, vinyl acetate / vinyl versatate copolymer (VAVeaVA), and the like. be able to. Among them, ethylene / vinyl acetate copolymer (EVA) can be preferably used.

The addition amount of these synthetic resin-based admixtures is 1 to 10 parts by weight, preferably 1 to 5 parts by weight based on 100 parts by weight of the base material. If the addition amount is less than 1 part by weight, the effect of addition is small, the obtained falling coating agent is easily peeled off from the sprayed surface, and even if added in excess of 10 parts by weight, the effect of further improving the adhesive force is small,
On the contrary, the fire resistance performance may be reduced.

(6) Spraying construction 50 to 70 parts of water is added to 100 parts by weight of the coating material of the present invention and kneaded. When the synthetic polymer additive is an aqueous emulsion, it is blended in consideration of the water content.

The obtained kneaded material is sprayed to a required thickness on building steel beams and columns using a mortar pump, a mortar spraying machine, or the like. In some cases, it may be applied by trowel coating. In that case, the kneading water content is adjusted to obtain a kneaded material having a consistency suitable for trowel coating.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to Examples. In the following Examples and Comparative Examples, unless otherwise specified.
Parts and percentages are by weight.

Example 1 Cement: White cement (Nippon Cement Co., Ltd.)
10 parts Lightweight aggregate 1: 1 (weight) mixture of expanded perlite (Asano Perlite) and vermiculite (Nippon Refractory Co., Ltd.) 20 parts Endothermic substance Aluminum hydroxide (Nippon Light Metal Co., Ltd.)
After mixing 70 parts of water and thoroughly mixing the mortar mixer, 60 parts of water and water-soluble resin: Hi Metrose 90SH15000 (Shin-Etsu Chemical Co., Ltd.)
0.2 part of admixture: Movinyl powder E-40 (manufactured by Hoechst Gosei Co., EVA) 2.0 parts was added and kneaded.

 Various performances of the obtained kneaded material were evaluated by the following.

(A) Adhesion state The kneaded material was sprayed on an upright transparent plastic surface using a mortar pump and a spraying machine, and immediately the adhesion state of the kneaded material sprayed from the opposite surface was visually observed. Was evaluated.

：: There are no air bubbles on the adhered surface and they are uniformly adhered.

Δ: Uniformly adhered, but bubbles are conspicuous on the adhered surface.

X: Coarse air bubbles are present on the adhered surface and are adhered only partially.

(B) Adhesive strength (kgf / cm ² ) It was sprayed on a steel structure for construction in the same manner as above, and then left for 4 weeks to cure. The thickness of the reinforced film was 30 mm.
With a knife on the cured body, to a size of side length 40 × 40 mm, and
Make a cut until it reaches the steel frame, attach the attachment to the surface with an epoxy-based adhesive, pull it using a spring balance, read the scale on the spring balance when the cured body peeled off the steel frame surface, and check the adhesive strength (kgf / m ² ).

(C) Compressive strength (kgf / m ² ) Conforms to JIS A5201.

(D) Fire resistance and dry specific gravity A cube having a size of 70 mm square is molded and cured, and after being sufficiently dried and cured, its specific gravity is measured. Then, a thermocouple is installed at the center, and the molded body is cooled to 1000 ° C. It was placed in a furnace, and the time (minutes) until the center temperature of the molded body reached 350 ° C. was measured, and the degree of fire resistance was determined based on the time.

(E) Dry shrinkage amount Complies with JIS A1129.

 Table 1 shows the evaluation results.

Comparative Examples 1 to 11 The same materials as in Example 1 were used and evaluated in the same manner as in Example 1 with the formulations shown in Table 1. Table 1 shows the evaluation results.

[Effects of the Invention] Since the refractory coating material of the present invention has a significantly smaller amount of cement than the conventional cement-based refractory coating material, there is no crack due to shrinkage after drying and curing, and the water-soluble resin and the synthetic resin By adding the admixture, the blending amount of the lightweight aggregate and the endothermic substance, especially the blending amount of the endothermic substance, can be increased, and the fire resistance is excellent, and the adhesion to the sprayed surface is good, and the curing is performed. The later adhesive strength is also excellent.

Claims (1)

(57) [Claims] (1) 2.5 to 12% by weight of cement, 5 to 30 of lightweight aggregate
0.1 to 1.0 parts by weight of a water-soluble resin and 1 to 10 parts by weight of a synthetic resin-based admixture with respect to 100 parts by weight of a base material composed of a weight% and an endothermic substance of 58 to 92.5% by weight. Fireproof coating.