JPH01278439A - Fireproofing material - Google Patents

Abstract

PURPOSE:To obtain the title material with improved fluidity, prevented from cracking and sagging when sprayed by using a small amount of a surfactant and a clay mineral having double-chain crystal structure and by including air bubbles in a paste to be used as the final fireproofing material. CONSTITUTION:The objective fireproofing material comprising (A) 20-50wt.% of rock wool, (B) 25-60wt.% of a hydraulic inorganic binder, (C) 5-30wt.% of a fireproofing admixture, (D) 0.1-1.5wt.% of a thickening agent, (E) 0.01-0.1wt.% of a surfactant, and (F) 1-15wt.% of a clay mineral having a double-chain crystal structure. This pasty fireproofing material is sprayed to form a fireproofing coating layer. Said pasty material is good in fluidity, freed from debonding, being prevented from sagging.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a wet spraying construction method for fireproof coating materials, specifically, rock wool-based materials that do not cause cracks, drips, or peeling.
The purpose of this paper is to protect metal structural members of buildings from high temperatures during a fire, regarding a fireproof covering material with excellent heat insulation properties used in the wet type 1 method that can be sprayed thickly.

[Conventional technology]

BACKGROUND ART In buildings, especially in building construction, the number of buildings made of steel is increasing in order to cope with the rise in height and because of its ease of construction. The strength of steel frames rapidly decreases when the temperature exceeds 450°C. If the temperature of the steel frames used as structural materials for buildings exceeds this temperature in the event of a fire, problems will arise in the integrity of the building.

To prevent this, the Building Standards Act requires that the surface of the steel frame be covered with a fire-resistant and heat-insulating material.

Most of the inorganic insulation materials currently used as fireproof coatings are made from rock wool.

There are two types of construction methods: wet spraying and dry spraying. TECHNICAL FIELD The present invention relates to a fireproof coating used in wet spraying construction methods.

Wet spraying method uses rock wool and portland cement,
Water is added to a material containing hydraulic inorganic binders such as gypsum, thickeners, clays such as clay, bentonite, fire-resistant admixtures such as barite, vermiculite, etc., and the mixture is kneaded with a mixer to form a paste. Compressed air is blown through a hose through a pump and a nozzle, and a paste-like fire-resistant coating material is sprayed onto the steel surface by the force of the ejected air, forming a fire-resistant coating layer. Since this paste-like material needs to be pumped through the hose by 100 to 200 n%, it must have good fluidity and properties such that water and solid material do not separate during pumping. In addition, as another required property, the water in the paste material that is sprayed to cover the steel frame moves before the hydraulic inorganic binder hardens, causing so-called "sagging". It is necessary that the fireproof coating layer does not crack or peel off after curing and drying, and that the fireproof coating layer does not crack or peel off due to the progression of cracking.

In order to solve these problems, as a first method, Japanese Patent Publication No. 50-24973 and Japanese Patent Publication No. 53-385
In Publication No. 25, a surfactant and a thickener are mixed, and air bubbles are mixed into the paste by the foaming power of the surfactant, and the fluidity of the paste is improved by the bearing effect.
It has been proposed that thickeners increase the water retention and bubble stability of coatings, prevent water separation, and improve adhesion to steel frames. A second method is to mix alkali-resistant glass fibers into the fireproof coating layer as disclosed in Japanese Patent Laid-Open No. 56-63880 to prevent cracks caused by drying, even if drying shrinkage occurs. One method is to use the strong tensile strength of glass fibers to suppress the appearance of cracks on the surface, and the third method is to insert a steel lath mesh into the base for spraying, which prevents drying shrinkage from appearing intensively and makes it fireproof. There are methods such as dispersing it into small cracks that do not affect the properties.

[Problem to be solved by the invention]

The fireproof coating material obtained by the first method has good fluidity and is satisfactory in that it does not clog in the pressure hose or separate water in the hose, but the movement of water within the sprayed layer is
It is still large and suffers from large amounts of drying shrinkage, so it has the disadvantage of being prone to cracking. The second crack prevention method shows excellent properties in that the alkali-resistant fiber prevents cracks even if the amount of drying shrinkage is large, but it tends to lack fluidity and the movement of moisture within the sprayed layer is large. “Who” is easy.

In addition, alkali-resistant glass fibers tend to get entangled in the paste mixture and form granular clumps, which can clog the discharge port at the tip of the fireproof coating spray nozzle, making it impossible to spray efficiently, and the cost is high. ing. The third method of inserting a lath net is rarely used because it takes a lot of time to construct the lath net.

The present invention addresses the disadvantages of conventional wet rock wool fireproof coating materials, such as large drying shrinkage, insufficient fluidity, large moisture movement within the sprayed fireproof layer, and the sprayed layer tends to sag. This overcomes the drawback of not being able to spray thick layers at once, and provides a product that is inexpensive and has good workability.

[Means to solve the problem]

As a result of intensive research aimed at solving these problems all at once, the present inventors have developed a surfactant consisting of alpha olefin sulfonic acid sodium salt, linear alkylbenzene sulfonic acid sodium salt, fatty acid seracun, etc., and Seviolite, It was discovered that by simultaneously using a small amount of attapulgite, the amount of water required when kneading fireproof coating materials could be drastically reduced without impairing fluidity, and this invention was completed. In this specification, "kamechi" means "wt%" unless otherwise specified.

The raw material for the fireproof coating material used in the present invention is Rockwool 2
5 to 50%, hydraulic inorganic binding material 25 to 60%, fire-resistant admixture 5 to 309G, thickener 0.1 to 1.5%, surfactant 0.01 to 0.1%, and double chain. Consists of 1-15% clay minerals with a mold structure.

All or part of these raw materials are mixed in advance at a factory, transported to the construction site where they will be used, added with an appropriate amount of water, kneaded in a mixer, pumped through a hose, and sprayed onto the desired spraying location.

Among the materials, rock wool uses granular cotton specified by JIS-A-9501 as a raw material, and its particle size may be small if the surface of the coating layer is desired to be hard, or large if insulation is required, depending on the purpose of use. can be changed as appropriate. If the amount of rock wool is less than 251, the density of the coating layer increases, and the paste of the sprayed fireproof coating material becomes too heavy and easily peels off from the sprayed area, making it impossible to spray thickly at once, which reduces the efficiency of construction. It won't go up.

In addition, since it is heavy, a large amount of material is required, which is not economical. If it is more than 50 cm, the fluidity of the paste will be poor and water will easily separate.Portland cement, gypsum, or a mixture thereof is used as the hydraulic inorganic binder.

If the amount of the hydraulic inorganic binder is less than 251, the strength of the fireproof coating layer will be insufficient, and if it is more than 601, the density of the paste will increase and only thick spraying will be possible.

Among fire-resistant admixtures, lightweight aggregates such as vermiculite and pearlite are useful for reducing the weight of the coating material and reducing the amount of drying shrinkage.If the amount is less than 5-1, it is ineffective, and if the amount is 30-1 or more, the fire-resistant coating is Since it is too lightweight, it does not have the required strength. Other admixtures include chrysotile asbestos, wollastonite, and kaolin clay.

Particulate charcoal is appropriately used to prevent separation of water from the paste, improve fluidity, and improve adhesion of the sprayed paste.

Particularly suitable clay minerals having a double-chained crystal structure for use in the present invention are sepiolite, attapulgite, and palygorskite. These clays with special structure have the effect that the amount of surfactant and water in the paste can be reduced. However, if it is less than 11, it is not effective in preventing cracking due to drying shrinkage or water separation, and if it is more than 15, a large amount of water is required for cross-conducting, and it tends to peel off when sprayed.

Thickeners are used to improve fluidity during pumping through a hose, prevent water separation, and stabilize bubbles in the surfactant. Thickeners that can be used include methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, polyvinyl alcohol cellulose, hydroxypropyl cellulose, polyvinyl alcohol,
l<IJ Ethylene oxide, sodium polyphosphate, etc. If the amount is less than 0.1%, there will be no effect, and if it is more than 1.5%, drying shrinkage will increase, causing cracks after drying.

The surfactant used in the present invention may be one that can generate a large amount of stable bubbles when added to the raw materials and stirred with water, and that does not interfere with the curing of the hydraulic inorganic binder. Examples include alpha olefin sulfonic acid sodium salt, linear alkylbenzene sulfonic acid sodium salt, fatty acid seracun, and the like.

If the amount of surfactant is less than 0.02%, the foaming properties will be low and there will be no effect of reducing the amount of water to be mixed. On the other hand, 0.
Even if 1- or more is added, the bubble effect remains the same, and as the amount of surfactant increases, the surface tension of water decreases, making it easier for water to separate from the paste, causing it to fall from the spraying surface due to its own weight. , undesirable phenomena such as "dripping" are likely to occur.

A paste made by kneading a fireproof coating material containing sepiolite, attapulgite, etc. can significantly reduce the erosion of surfactants. At the same time, the amount of water required to make the paste fluid is smaller than that required for other clay minerals, such as chrysotile asbestos, kaolin clay, and bentonite, so there is no ``sag'' during spraying. ” and can be sprayed thickly. Although it is not fully clear why these effects are obtained, it is thought to be due to the following reasons.

Since the fibers of chrysotile asbestos are thin and long, they are dispersed in the paste and become mat-like, and the air bubbles contained therein tend to become open cells, which tend to connect with each other and become larger and collapse. In addition, kaolin clay and bentonite have small particle diameters; kaolin clay is plate-shaped and is often less than 2 μm, and bentonite is often less than 0.2 μm, so the particles are connected,
It is difficult to form a stable thin film, and since the paste cannot surround and stably hold the air bubbles contained in the paste, the air bubbles are likely to collapse.

In comparison, sepiolite and attapulgite have a double-chain crystal structure and have a thickness of 10
Since it includes a fiber-like structure with a length of around 0A and several microns in length, it is easy to connect them to form a thin film.

Therefore, fine air bubbles in the paste exist surrounded by a film of seviolite and attapulgite. As a result, many fine air bubbles can be mixed into the paste, the stability of the air bubbles is improved, there is less variation in fluidity, the bearing effect of the air bubbles is also good, and water added to improve fluidity is reduced. It seems possible to reduce this.

Example The present invention will be explained below with reference to Examples.

Example (1-4) Raw materials were prepared according to the formulations shown in Table 1 and mixed in a blender.

Polyethylene oxide (PEO) and methyl cellulose (MC) were used as thickeners, and sodium alpha olefin sulfonate was used as surfactant.

The above mixed raw materials 110 to 'e were taken, and while being mixed with a mortar mixer, water was added and kneaded for 5 minutes until a paste with predetermined fluidity was obtained. This paste was pumped using a Nijiku mortar pump and sprayed onto a vertically erected steel plate, and water separation, drying shrinkage, and sprayable thickness were measured.

The fluidity was measured in accordance with JIS R-521 "Flow test in the physical test method for cement", and the amount of water was determined so that the values were approximately the same in each example.

Water separation was determined by visually observing the amount of water flowing down from the paste layer sprayed onto a vertical surface.

Drying shrinkage was determined in accordance with JIS A-1129r Mortar and Concrete Length Change Test Method, and dimensional changes were measured after 4 weeks, and the results are shown in the bottom column of Table 1.

Table 1 shows the compounding ratios of comparative examples. The test method and measurement method were exactly the same as in the examples, and the results are shown in the lower column of Table 1.

Comparative Example 1.2.3 shows the fluidity, adhesion, and
This is an example of a formulation used when crack prevention is required. This shows that even if the amount of surfactant is larger than in Example 1.2, the amount of water mixed cannot be reduced in order to achieve the same fluidity as the product of the present invention.

Blank space below [Effects of the Invention] In the present invention, the amount of surfactant used is less than 0.1% by simultaneously using a surfactant that does not hinder the curing of the inorganic binder and a clay mineral with a double-chain crystal structure. With this, we were able to incorporate a large amount of air bubbles into the paste used as a fireproof coating, and we were able to reduce the amount of water mixed while ensuring fluidity. In this industry, the special public
As stated in Japanese Patent No. 4973, when the amount of surfactant is less than 0.1%, the inclusion of air bubbles is reduced.
It was said that the paste would become unusable.

By reducing the amount of surfactant and allowing a large amount of air bubbles to be included in the paste, the following effects were achieved.

a) The drying shrinkage rate is reduced and no cracks appear after drying.

b) Since there are many air bubbles and little water, the density of the paste is low and thick spraying is possible.

C) Since there is less water and less surfactant particles, there is less movement of water in the sprayed paste layer, and there is no "dripping" or peeling.

Claims (1)

[Claims] Rock wool 25-50% by weight, hydraulic inorganic binder 2
5-60% by weight, fire-resistant admixture 5-30% by weight, thickener 0.1-1.5% by weight, surfactant 0.01-0.1% by weight, and has a double-chain crystal structure. A fireproof coating material for wet spraying construction consisting of 1 to 15% by weight of clay minerals.