JP2583186B2 - Calcium silicate molding and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refractory calcium silicate molding used mainly in the field of construction and a method for producing the same.

[0002]

2. Description of the Related Art Among building materials, a calcium silicate molded article is one of those used in places where some resistance to fire such as fire resistance, fire resistance and non-flammability is required. The calcium silicate molded body is used as a wall material, a roof material, a ceiling material, a floor material, and the like, and is also useful as a fire-resistant coating material for securing fire resistance of a steel frame in a steel-frame building.

[0003] However, the calcium silicate molded article is inherently highly hygroscopic, and usually has a water content of about 10% when used in a building. Then, when a fire is encountered when the water content is relatively high, the water contained therein is rapidly vaporized, causing destruction and steam rupture. In addition, 750 ° C even if steam rupture does not occur.
When the temperature is higher than the above, a large shrinkage occurs, which causes cracks and partial peeling.

[0004]

The steam rupture occurs because there is no escape route for water vapor generated abruptly inside the calcium silicate molding due to a rapid rise in temperature, and increases the permeability of the calcium silicate molding. It was found that steam rupture would be avoided if a steam escape route was secured. That is, in the case of an ordinary tobermorite-based calcium silicate molded product, the air permeability is about 1.5 × 10 ⁻⁵ ml · cm / sec · cm ²
-It was confirmed that, when the water content was not less than cmH ₂ O, almost no water vapor rupture occurred even when a material having a water content of about 10% was subjected to a fire resistance test.

[0005] It is possible to produce a calcium silicate molded body having a high air permeability as described above, for example, by taking into account the type and mixing ratio of the filler and the molding conditions. Absent. However, simply forming a porous structure having a high air permeability results in a calcium silicate molded article having insufficient strength and is not practical in many cases. Therefore, in order to improve the fire resistance of the calcium silicate molded article by increasing the air permeability, a method for increasing the air permeability while securing the strength necessary for practical use must be found.

[0006]

Means for Solving the Problems The object of the present invention is to mix a raw material of silicic acid, a raw material of lime, a reinforcing fiber and a filler with water, to form a dehydrated product, and to mold the obtained product in an autoclave under conditions of tobermorite formation. In a method for producing a calcium silicate molded body which generates a tobermorite from a silicic acid raw material and a lime raw material by heat treatment, silica is used for all or a part of the silicic acid raw material and 10 to 50% by weight based on the total forming raw material. The invention has been achieved by adding gypsum in an amount to give a forming raw material.

[0007] The present invention also provides the high calcium siliceous molded article obtained by the production method of the present invention, i.e. containing a type II anhydrous gypsum in a matrix of tobermorite quality and permeability is 1.5 × 10 ^{- 5} ml ・ cm / sec ・ cm ²・ cmH ₂ O or more,
An object of the present invention is to provide a calcium silicate-based molded product having a bending strength of 80 kgf / cm ² or more.

[0008] In the production method of the present invention in which dihydrate gypsum is added to a forming raw material, the added dihydrate gypsum is produced in a process in which a molded product is subjected to autoclave treatment and a silicic acid raw material and a lime raw material react to form tobermorite. Converts to anhydrous type II gypsum (dihydrate gypsum changes to type II anhydrous gypsum when heated to a temperature of about 135 ° C or more even under saturated steam. The time required to cause this reaction depends on the heating temperature However, since the temperature and time conditions required to sufficiently generate tobermorite from the silicic acid raw material and the lime raw material may be milder, the anhydrous gypsum formation is completed before tobermorite is generated.)

[0009] Gypsum undergoes a volume reduction of about 40% when changing from dihydrate gypsum to type II anhydrous gypsum. This change occurs in parallel with the formation of the tobermoritic matrix, so that the product obtained after autoclaving has fine pores formed along the uniformly dispersed anhydrous gypsum particles. The micropores formed as described above become a ventilation path together with the micropores formed regardless of the volume reduction of the gypsum, so that a product having a large air permeability as described above is obtained ( These effects are
It cannot be expected at all if anhydrous gypsum is added to the molding raw material. ).

When the gypsum added to the forming raw material is acicular crystals, the type II anhydrous gypsum remaining in the final product also becomes acicular crystals. The volume shrinkage of the needle-like crystals causes elongated pores to be formed, and the elongated pores are easily connected to other pores to easily form continuous pores. Therefore, the use of needle-like crystal dihydrate gypsum increases the permeability of the product. It is advantageous. The acicular crystal type II anhydrous gypsum formed from the acicular gypsum dihydrate also has an action of inhibiting the shrinkage of the calcium silicate matrix based on its acicular shape. ° C
Is reduced when heated to a high temperature exceeding.

Furthermore, SO ₄ produced by dissociation of gypsum ^-
The ions have a favorable effect on the formation of calcium silicate hydrate crystals in the autoclave treatment, and provide a calcium silicate matrix having a small heat shrinkage. Based on the action of gypsum as described above, according to the production method of the present invention, it is possible to increase the air permeability without significantly deteriorating the physical properties of the product, and to produce a fire-resistant calcium silicate molded article.

In the production method of the present invention, the silicic acid raw material is
At least part of it must be quartzite. The reason that the silicic acid raw material used is limited in this way is that the change from the dihydrate gypsum to the type II anhydrous gypsum proceeds most easily when silica is used. Other silicic materials may delay the dehydration of gypsum, especially with ferrosilicon dust. Diatomaceous earth is an example of a silicic acid material that can be used in combination with silica stone without much adverse effect on dehydration of gypsum.

[0013] The lime raw material, reinforcing fiber, filler and the like are not particularly limited, and the lime raw material is slaked lime, quick lime, Portland cement, etc., and the reinforcing fiber is pulp, alkali resistant glass fiber, carbon fiber, organic fiber, etc. As a filler such as synthetic fiber (for example, polypropylene fiber or aramid fiber), any of fillers ordinarily used in the production of a calcium silicate molded body, such as wollastonite, calcium carbonate, magnesium carbonate, and talc, can be used. .

The dihydrate gypsum added to these raw materials is preferably in the form of needle-like crystals for the above-mentioned reasons, but amorphous powder may be used. The addition amount is set to be about 10 to 50% by weight based on the total forming raw material including gypsum. It is not desirable to add a large amount exceeding 50% by weight because the adverse effect of lowering the strength becomes significant. A particularly preferred addition rate is 20 to 30% by weight.

The raw material to which gypsum is added is mixed with a large amount of water according to a conventional method for producing a calcium silicate molded product, and the resulting slurry mixture is subjected to dehydration molding by a papermaking method or a press molding method. The obtained molded product is heat-treated in an autoclave to produce tobermorite from a silicic acid raw material and a lime raw material, and also convert gypsum to type II anhydrous gypsum. The temperature required for this treatment is about 165 to 200 ° C. and the time is about 3 to 20 hours.

The molded body after the treatment is taken out of the autoclave and dried with hot air. The calcium silicate-based molded product according to the present invention is used as a steel frame covering material in a steel-frame building utilizing its excellent fire resistance, and is used as a wall material, a roof material, a ceiling material, a floor material and the like in various buildings. be able to.

[0017]

EXAMPLES Calcium silicate compacts were produced according to the method of the present invention with the raw materials shown in Table 1. Further, as a comparative example, a calcium silicate molded body was produced by mixing the raw materials shown in Table 2. The manufacturing conditions are as follows. Molding: The sheet is formed by a round screen forming machine according to a conventional method to obtain an eight-layer laminated green sheet (total thickness: 8 mm). Autoclave treatment Condition A: 180 ° C. × 10 hours Condition B: 165 ° C. × 10 hours Drying: After completion of the autoclave treatment, the temperature is lowered to 100 ° C., then taken out of the autoclave and dried with hot air at 105 ° C.

The obtained product was measured for density and bending strength, checked for the state of gypsum, and tested for properties by the following methods. The state of the gypsum was confirmed by X-ray diffraction and scanning electron microscope observation. Measurement of air permeability: BS1902 Part 1A Evaluation of fire resistance: 900 mm of a sample whose water content was adjusted to 7%
Shred into corners, screw on lightweight steel frame and attach to fire test furnace. After that, BS476. According to Part 20, the temperature is raised to 556 ° C for 5 minutes, to 821 ° C for 30 minutes, and to 1050 ° C for 120 minutes. The presence or absence of steam rupture and crack generation due to this heating is examined. Dimensional change due to heating: A sample having a width of 5 mm and a length of 20 mm was heated under the same heating conditions as in the above fire resistance test, and was heated to 1000 ° C.
The dimensional change in the longitudinal direction when the
by).

The results are as shown in Tables 1 and 2.

Table 1 Examples 1 to 5 Example 1 Example 2 Example 3 Example 4 Example 5 Raw material blending (parts by weight) Gypsum dihydrate (needle-shaped crystals) 30 10 20 30 〃 (irregular shaped powder) 30 W Lastnite 22 20 10 22 22 Silica stone 11 22 22 11 11 11 Diatomaceous earth 10 10 10 10 10 Slaked lime 22 33 33 22 22 Pulp 55 5 55 5 5 Autoclave conditions A A A A B Product properties Gypsum state Bulk density (g / cm ³ ) 0.91 0.92 0.93 0.89 0.88 Flexural strength (kgf / cm ² ) 100 138 118 95 83 Air permeability (× 10 ⁵ ) 16.0 1.5 3.4 7.0 35.0 Heat test Steam burst None None None None None Cracking None None None None None Dimensional change (%) +0.3 −1.4 −0.70 +0.2

[0020]

Table 2 Comparative Examples 1 to 6 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Raw Material Formulation (parts by weight) Anhydrite gypsum needle crystal 30 20 10 wollastonite 46 32 22 22 22 silica stone 14 21 11 16 21 Diatomaceous earth 10 10 10 10 10 Slaked lime 25 32 22 27 32 Pulp 55 5 55 55 Autoclave conditions A A A A A Product properties Gypsum condition --- Anhydrous needles Anhydrous needles Anhydrous needles Bulk density (g / cm ³ ) 0.95 0.88 0.87 0.88 0.88 Flexural strength (kgf / cm ² ) 71 102 62 75 102 Air permeability (× 10 ⁵ ) 20.2 1.2 10.0 3.0 1.3 Heat test Steam rupture No Yes No No Yes Cracking Yes Yes Yes Yes Yes Dimensions Change (%) −1.7 −3.3 −1.7 −3.2 −4.0

[0021]

As described above, according to the present invention, it is possible to increase the permeability of the calcium silicate molded product without deteriorating the physical properties, and to provide a product excellent in fire resistance.

Claims (3)

(57) [Claims] 1. A tobermorite type matrix containing type II anhydrous gypsum and having an air permeability of 1.5 × 10 ⁻⁵ ml · cm / sec ·
A calcium silicate-based molded product having a cm ² · cmH ₂ O or more and a bending strength of 80 kgf / cm ² or more. 2. The calcium silicate compact according to claim 1, wherein the type II anhydrous gypsum is a needle-like crystal. 3. A silica raw material, a lime raw material, a reinforcing fiber and a filler are mixed with water and dehydrated and molded, and the obtained molded product is heat-treated in an autoclave under tobermorite-forming conditions to form a mixture with the silica raw material. In a method for producing a calcium silicate refractory heat insulating material for producing tobermorite from a lime raw material, silica water is used for all or a part of the silicic acid raw material and an amount of 2 water which is 10 to 50% by weight based on the total forming raw material. A method for producing a calcium silicate molding, characterized by adding gypsum to a molding raw material.