JPH0477373A - Fireproof coating material - Google Patents

Abstract

PURPOSE:To obtain a fireproof coating material causing expansion at a high rate by uniform foaming at the time of fire and exhibiting superior heat insulating property by incorporating a specified substance as a blowing aid into a fireproof coating material having a prescribed compsn. and giving a coating film convertible into a heat insulating covering layer by foaming at the time of a fire. CONSTITUTION:Thermally expandable microcapsules (e.g. 'Matsumoto Microsphere F30(R)' made by Matsumoto Fats and Oils Pharm. Co. are incorporated as a blowing aid into a fireproof coating material consisting essentially of a thick aq. soln. of alkali silicate (e.g. No.3 sodium silicate) and a heat resistant inorg. filler (e.g. a silica powderwollastonite mixture) and giving a coating film convertible into a heat resistant covering layer by foaming at the time of a fire.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a coating material for building steel frames that provides a coating film that foams in the event of a fire and becomes a coating layer with good heat insulation properties.

[Conventional technology]

A fire-resistant coating material made by blending a heat-resistant inorganic filler with a concentrated aqueous alkali silicate solution such as water glass, and further blending a compound that generates water vapor or inert scum when thermally decomposed and becomes an oxide with a high melting point. Or, Special Public Service 1974-22
It is known from Japanese Patent Publication No. 689, Japanese Patent Publication No. 55-18673, etc. This coating material is applied to the steel frame parts of buildings in the same way as ordinary paint, and when it dries, it forms a hardened coating film. However, when it is heated in a fire, the alkali silicate cured product softens and steam vapor builds up inside. It foams as a result of the generation of decomposition gas and forms a coating layer with good insulation properties, which insulates the steel frame from the high heat of a fire and prevents the structure of the building from collapsing.

[Problem to be solved by the invention]

Although the above-mentioned fire-resistant coating materials are extremely effective in improving the fire resistance of buildings, there is still room for improvement in their foaming properties when heated by fire. That is, while coarse bubbles are generated, there are often areas where little foaming remains, and as a result, the improvement in heat insulation properties of the coating film due to foaming is not so remarkable.

Therefore, in order to further enhance the effectiveness of the alkali silicate fire-resistant coating, the present invention aims to improve the coating so that foaming becomes more uniform and noticeable when the coating film is exposed to high temperatures. This is the purpose.

[Means to solve the problem]

The fire-resistant coating that the present invention has succeeded in providing consists of thermally expandable microcapsules for a composition essentially similar to conventional fire-resistant coatings, consisting primarily of an aqueous alkali silicate solution and a heat-resistant inorganic filler. is blended as a foaming aid.

Thermal-expandable microcapsules blended into this fire-resistant coating material as a foaming aid cause significant expansion when heated to about 100° C. or higher. Particularly suitable heat-expandable microcapsules to be incorporated into the coating material of the present invention include 120
The material expands in volume by at least 20 times when heated to .degree. C. for 1 minute.

Such microcapsules use a polymer such as vinylidene chloride copolymer, which softens at temperatures above about 80°C and can undergo a high rate of plastic deformation, as the shell wall constituent material, and whose boiling point is higher than the softening point of the shell wall constituent material. It is obtained by using a substance below the point as an inclusion substance. Furthermore, the material constituting the shell wall of the microcapsules must be stable for a long period of time in the cured water glass product and must have a property that it can be retained in the capsule for a long period of time without allowing the encapsulated material to pass through. The encapsulated substance is not particularly limited in relation to the present invention, except that it has a boiling point as described above, but examples of microencapsulated substances that can be obtained at low cost include There are hydrocarbons below about 908C. An example of a commercially available microcapsule that meets these requirements is Matsumoto Microspheres (manufactured by Matsumoto Yushi Pharmaceutical Co., Ltd.).

The blending ratio of thermally expandable microcapsules is approximately 10% or less,
Preferably it is about 2-5%. The higher the blending ratio of thermally expandable microcapsules, the higher the foaming ratio in the event of a fire. However, if the ratio is too high, the strength of the film will be insufficient and cracks will occur as a result of expansion.

The components other than the thermally expandable microcapsules described above are not particularly different from conventional fireproof coating materials.

Examples of alkali silicate aqueous solutions include sodium silicate aqueous solution,
So-called water glass can be used. Sodium silicate comes in sizes 1 to 4, but products 1 and 2 have too high a viscosity and require the addition of water, and they also contain too much alkali, so they tend to have poor heat resistance and weather resistance. , No. 3 product is suitable for use as is. Water resistance can be improved by adding potassium silicate which is compatible with sodium silicate.

As the inorganic filler, silica powder, wollastonite, etc. are preferable because they have an excellent effect of improving heat resistance and coating strength, but in addition to these, various refractories, powders such as clay minerals, and even ceramic fibers can be used. etc. can be used. When No. 3 sodium silicate is used as the alkali silicate, the preferred blending ratio of the inorganic filler is about 50 to 65% by weight based on the total weight of the same components.

Mix all ingredients evenly. Also, if necessary, water is mixed to adjust the viscosity to an appropriate value for coating.

The fireproof coating material of the present invention, like conventional coating materials of this type,
In addition to being applied to the surface of the steel frame once the steel frame has been erected, it can also be applied to the steel frame before it is erected at a factory.

The hard coating film formed by drying the alkali silicate is similar in appearance to that of conventional fireproof coating materials, but thermally expandable microcapsules are uniformly distributed therein. Then, when a fire occurs and the temperature rises, the low-boiling-point inclusion material in the microcapsules evaporates in parallel with the softening of the alkali silicate matrix, and the generated gas inflates the capsule shell wall due to its pressure. The microcapsules expand while pushing away the softened alkali silicate, forming fine bubbles of each microcapsule in the coating film. Some of the gas generated in the capsule passes through the shell wall and exits the capsule. Also, shell wall rupture may occur and all of the gas within the capsule is released from the capsule. The gases released from the capsules also participate in the formation of bubbles together with water vapor produced by vaporization of the contained moisture. As a result of the above, the coating film will surely contain a much higher and more uniformly distributed air bubbles and will expand at a higher magnification than if it did not contain microcapsules. If the microcapsules have low thermal expansion, the capsule shell wall will be destroyed at a high rate from an early stage of heating, and the gas utilization rate of the encapsulated material will be poor, resulting in a low expansion ratio of the coating film.

〔Example〕

In the following examples, "parts" means parts by weight.

Example 1 Fireproof coating material consisting of 62 parts of No. 3 sodium silicate, 19 parts of silica powder, and 19 parts of wollastonite, and thermally expandable microcapsules/Matsumoto Microspheres F30 (
A fireproof coating material obtained by mixing 1 to 7 parts of Matsumoto Yushi Pharmaceutical Co., Ltd. product) was air-dried in a mold and formed into a disk shape with a thickness of 2III11.

The obtained test piece of the coating film model was heated at 100° C. for 15 minutes, and then the thickness was measured. Subsequently, 500 test pieces were
The sample was placed in an electric furnace at ℃ and heated for 15 minutes, and after cooling, the thickness was measured. The expansion rates (thickness increase rates) determined from the measurement results are as shown in Table 1.

Table 1 Example 2 2 parts of the same microcapsules used in Example 1 were added to 55 parts of No. 3 sodium silicate and 45 parts of talc, mixed, and placed on a 3.2+ am iron plate to a thickness of 6+a+e. I applied it to make it look like this.

The resulting test piece was air-dried for two weeks, then supported horizontally with the coated side facing down, and heated for 30 minutes with the flame of a Bunsen burner directly hitting the coating.

The flame temperature was 970°C. After 30 minutes of heating, the temperature of the iron plate directly above the heating surface was 140°C.

After cooling, the coating film in the area hit by the flame swelled to about four times the thickness, and when it was cut open, the inside was found to have a diameter of 50 to 200 mm.
Microscopic bubbles of μm size were uniformly distributed.

Comparative Example A test piece was prepared in the same manner as in Example 2, except that no microcapsules were blended, and the same heating test as in Example 2 was conducted.

After 30 minutes, the temperature of the iron plate directly above the heating surface reached 240°C.

The paint film expanded approximately three times as much, but when it was cut open, large cavities were found in the surface layer, and large air bubbles with a diameter of 2 to 3 mm were also observed in the area close to the iron plate.

〔Effect of the invention〕

As mentioned above, since the alkali silicate fire-resistant coating material of the present invention contains thermally expandable microcapsules as a foaming aid, the coating film will not contain the thermally expandable microcapsules in the event of a fire. By utilizing the gas of the substance without wasting it, it foams uniformly and expands at a high magnification, resulting in excellent heat insulation properties. Therefore, according to the covering material of the present invention, it becomes possible to further improve the fire resistance performance of a steel frame building. Additionally, a thinner coating is required to achieve the same fire resistance as with conventional coatings of this type, allowing for an increase in the effective volume of the building and a reduction in its own weight.

Claims (2)

[Claims] (1) Foaming of thermally expandable microcapsules in a fire-resistant coating material that is mainly composed of a concentrated aqueous alkali silicate solution and a heat-resistant inorganic filler and foams in the event of a fire to form a coating layer with good insulation properties. A fire-resistant coating material characterized by containing it as an auxiliary agent. (2) The fireproof coating material according to claim 1, wherein the thermally expandable microcapsules exhibit a volumetric expansion coefficient of at least 20 times when heated to 120° C. for 1 minute.