JPS6028788B2 - Manufacturing method of inorganic board material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing inorganic board materials such as calcium oxalate board materials and asbestos cement board materials.

Asbestos-cement board materials may be cured in an autoclave using saturated steam at temperatures as high as 160° C. and high pressure in order to improve the strength of the board material.

In particular, in the case of calcium silicate-based plate materials, it is essential to generate tobermonite crystals and the like through a hydrothermal reaction between silicic acid components and calcareous components, so the above-mentioned autoclave curing is always used. In the autoclave curing described above, a large number of uncured original plates are stacked and stored in an autoclave, and the stacked original plates are exposed to high temperatures and
Heated with high pressure steam. The temperature of the plate material immediately after being cured as described above is as high as about 150° C., and the plate material must be cooled in order to send the cured plate material to the next process.

Conventionally, the above-mentioned methods of cooling the plate materials include providing a slow cooling chamber separately from the autoclave and transporting the cured plate materials into the slow cooling chamber to cool them, or opening the lid of the autoclave and leaving the plate at room temperature inside the autoclave. Methods such as allowing air to naturally flow in are used, but because the boards are stacked and the efficiency of heat release from the center of the stacked boards is poor, in any of the above methods, it takes a long time, for example, one field time. It takes time.

The above-mentioned plate material immediately after curing has a high moisture content of, for example, 50%, and it is necessary to reduce the moisture content of the plate material to about 15% for processing the plate material in the board processing step and painting step after curing.
Normally, a drying room is used to dry these boards, but in this case too, the boards are stacked, and the dewatering efficiency from the center of the stack is poor, and dehydration is concentrated from the green ends of the boards. When a board is dried uniformly and is surprisingly thick, warping of the board is unavoidable, and there is a concern that delamination may occur, especially in the case of a board produced using a papermaking method.

Other disadvantages include that it depends on seasonal temperature and takes a long time to dry.

As mentioned above, the conventional cooling and drying methods for plate materials cured in autoclaves have the disadvantages mentioned above, and in particular those using gradual cooling chambers and drying chambers have disadvantages such as high equipment costs. There is also.

The present invention provides a method for manufacturing an inorganic board material that can uniformly cool and dry a board material cured in an autoclave in a short time, and can also keep equipment costs low.

That is, the first invention of the present application cures an inorganic plate material in a curing pot with high-temperature, high-pressure steam, and then reduces the pressure inside the curing pot to a predetermined pressure of 1 atmosphere or less without opening the lid of the curing pot. The method for producing an inorganic plate material is characterized in that the above-mentioned reduced pressure state is maintained until the temperature of the plate material reaches the boiling point temperature of water under the predetermined reduced pressure. The second invention according to the present application is to cure an inorganic plate material in a curing pot with high-temperature, high-pressure steam, and then reduce the pressure inside the pot to a predetermined pressure of 1 atmosphere or less without opening the lid of the curing pot. When the temperature drops to near the boiling point of water under the above-mentioned predetermined pressure, high-temperature, high-pressure steam is introduced into the pot again, and from then on,
A method for manufacturing an inorganic sheet material, characterized in that the above depressurization and supply of steam are repeated several times, and the final depressurized state is maintained until the temperature of the sheet material reaches the boiling point temperature of water under the predetermined reduced pressure. be.

In the present invention, an autoclave is used as the curing pot, and after curing the plate material, the inside of the autoclave is once brought to atmospheric pressure and then depressurized.

Due to this pressure reduction, the porous spaces within the plate material are also reduced in pressure along with the above pressure reduction, and the boiling point of water is lowered. Therefore, the moisture within the plate material boils and evaporates into the porous space. The heat of evaporation at this time also removes heat from inside the plate material, and the evaporated moisture is drawn out into the reduced pressure atmosphere inside the autoclave. Therefore, the plate material is cooled from the inside by the heat of evaporation, and as a result, the plate material can be sufficiently and uniformly cooled, and warpage, delamination, etc. of the plate material can be prevented. In the above, if the reduced pressure is too low, water will boil violently and there is a risk of internal destruction of the plate material, so the reduced pressure needs to be 300 to 5 Hg, preferably 10 Hg.

The boiling point of water for this reduced pressure of 10 mHg is approximately 50°C.
It is.

According to the inventor's experimental results, in the case of a standard calcium silicate board with a thickness of 11 ribs, a middle diameter of 45 mm, and a length of 303 mm, when the pressure inside the autoclave is reduced to 100 Hg, the temperature of the plate material is approximately 30 mm. It will reach 70:00 in minutes. The final cooling temperature of the plate material must be approximately 5,000 qo, and the time required for cooling is determined by the time required for cooling from 70 qo to 5,000 qo.

The cooling rate in this case largely depends on the rate at which evaporated water vapor within the plate is exhausted. In other words, the porous space within the plate material changes from a state where the temperature is 70q0 and the saturated steam pressure is about 230 orr, to the state where the temperature is 50q0 and the saturated steam pressure is about 10 orr.
It depends greatly on the speed at which the state is reached. The cooling process from 70°C to 50°C will be discussed below.

Now, suppose that gas at low pressure P,, P2 is separated by a partition wall having holes of area A, and the mean free path of the gas molecules is much larger than the hole size.
The flow rate Q, flowing into the gas is the average velocity of the gas molecules V
Then, Q,=\API.

On the other hand, the flow rate Q2 at which the gas at pressure P2 flows into the gas at pressure P, is Q2=sheep AP2.

When P, > P2, the gas at pressure P finally becomes pressure P
The flow rate Q flowing into the gas No. 2 is Q=Q. -Q2=Sheep A(P
・-P2) -■.

However, V is cc/sec, A is ground, P is Ton, and Q is T.
The unit is orrcc/sec. Next, the average velocity V of molecules at absolute temperature T with molecular weight M is ▽=〆Wanihada/Se
c-■.

), R=Lk, L: Avogadro's number, k: Borckmann's constant (1.38 x 10-16 ergs/degree) Therefore, ■
■From the formula, Q = A (magazine) (p'P2) = 3.6 rounds (voice) with (P'P2) /Sec -■.

However, in the case of a calcium silicate board, the board has a high porosity and the pore area A per unit area is large, so Q is large.

Therefore, the cooling from 70 oo to 50 qo described above is performed in a relatively short time.

Dehydration, and therefore drying, is carried out similarly to the cooling described above. In the case of an asbestos cement board, the pore area A per unit area is 4.0, and the above-mentioned Q is relatively small.

Therefore, before the final cooling step, the board is heated several times with reduced pressure, high temperature, and high pressure steam to lower the moisture content of the board to a certain extent, and then the final cooling is performed as described above. . When a board is reheated using high-temperature, high-pressure steam, the water vapor is sucked into the board, resulting in an increase in moisture content of about 1%.

However, since the high-temperature, high-pressure steam used for curing can be used, special equipment for reheating the board is not required, which is advantageous in terms of equipment. FIG. 1 shows an autoclave apparatus used in the present invention.

In FIG. 1, reference numeral 1 denotes an autoclave, to which a steam supply pipe 2 from a boiler and a gas vent valve 3 are connected.

21 is a valve inserted into the steam supply gas pipe 2.

11 is a lid of the autoclave 1.

A is a vacuum system connected to the autoclave 1, which includes a valve 4, multi-tube cooling tanks 5, 5, and a condensed water tank 6.
, a vacuum pump 7, and an exhaust tower 8.

9 is a water tank; 10 is a drainage pump for discharging condensed water in the condensed water tank 6 into the water tank 9; and 11 is a water supply pump for circulating the water in the water tank to the cooling pipe of the multi-channel cooling tank.

12 is a drainage pump for draining condensed water in the autoclave into the water tank 9.

Next, an embodiment of the first invention of the present application will be described.

In this example, the siliceous raw material is 15 to 55 parts by weight, the calcareous raw material is 0.4 to 1.2 in molar ratio to the silicic raw material, the cement is 2 to 2 parts by weight, and the asbestos is 5 to 25 parts by weight. , 1 to 15 parts by weight of pulp, 0.05 to 0.5 parts by weight of synthetic fibers, a total of 10 parts by weight, and 1 to 1 part by weight of monocarboxylic acid light metal salt.
In this method, a raw original plate is obtained by paper-making a mixed solution of raw materials and water containing parts by weight of 100% by weight, and this is cured and cooled using the above-mentioned autoclave apparatus.

In this example, in order to make the board material usable as an exterior wall material, the porosity of the calcium silicate hydrate was made small (pore area 10-6 to 10-7 times that of the board material surface), and the mo/carboxylic acid metal The important objective is to reduce the water absorption of the calcium oxalate hydrate plate by using salt as a water repellent, and in order to maintain the water repellency effect of the monocarboxylic acid metal salt, the curing conditions are is limited to autoclave curing for 8 to 1 hour in saturated steam at 4 to 8 atmospheres.

The purpose of each raw material and the reason for limiting the blending amount in the above production example are as follows. First, the reason why the monocarboxylic acid light metal salt is limited to 1 to 1 part by weight is that if it is less than 1 part by weight, the desired water repellent effect cannot be obtained, and if it is more than 1 part by weight, it will be rolled up and laminated using a making roll of a wet machine. This is because there is a concern about peeling between the thin film layers.

Calcium stearate is particularly effective as the monocarboxylic acid metal salt. The reason why the molar ratio of the calcareous raw material to the silicic acid raw material is limited to 0.4 to 1.2 is to suppress the generation of free lime and prevent the occurrence of efflorescence in the product.

Quicklime, slaked lime, carbide birch, etc. are used as calcareous raw materials, and lotus lacquer, lotus sand, clay, fluorosilicone dust, fly ash, etc. are used as silicic raw materials.

A portion of this siliceous raw material is left unreacted in the madrix, and this serves as an aggregate for the madrix. The total amount of silicic acid and calcareous material is 20 to 10 parts by weight, and if it is less than 2 parts by weight, the light weight of the calcium oxalate board cannot be achieved, and if it is more than 10 parts by weight, it will not be as strong as the cement described below. If the amount is too large, not only will it not be possible to impart sufficient strength to the raw original sheet immediately after cutting and peeling it off from the making roll, but the strength of the product will also be insufficient.

The reason for limiting the amount of cement added to 2 to 2 parts by weight is as follows.
If it is less than 2 parts by weight, the above-mentioned strength guarantee of the raw plate and product cannot be achieved, and if it is more than 2 parts by weight, the amount of cement will be too large.
This is because the characteristics of the calcium lotus acid plate will be lost.

The reason for adding asbestos is to improve the efficiency of drawing up the solid content in the raw material slurry and to maintain the strength and dimensional stability of the product.

The reason for adding pulp is to improve the papermaking efficiency and to improve the sawing properties, nailing properties, and other construction methods of the product.

The reason why the amount of pulp added was limited to 1 to 15 parts by weight is that 1
If the amount is less than 1 part by weight, the construction method cannot be improved much, and the amount of asbestos must be 25 parts by weight or more. If it is more than 15 parts by weight, the amount of asbestos can be reduced to 5 parts by weight or less, but the product strength and dimensions This is because stability is considerably reduced.

The reason for using synthetic fibers is to improve the impact strength of the product.

This synthetic fiber must not deteriorate under the above-mentioned curing conditions, and polypropylene fibers and polyvinyl alcohol fibers are effective as such fibers. The reason for limiting the amount of synthetic fiber added to 0.01 to 0.5 parts by weight is 0.
．． If the amount is less than 0.01 part by weight, the above-described improvement in impact strength will not be achieved sufficiently, and if it is more than 0.5 part by weight, not only will the quality be excessive in terms of impact resistance, but the bulk ratio of synthetic fibers will be large. This is because it becomes difficult to mix the same fiber into the slurry.

To carry out the embodiment of the first invention described above, first, raw materials selected from within the above range are mixed with water using a pulper to obtain a slurry having a raw material concentration of about 10%. As this mixed water, in addition to tap water and industrial water, condensate water containing a small amount of raw material removed during the papermaking process can be used. To prepare this slurry, pulp, synthetic fibers, and monocarboxylic acid metal salts may be mixed with water in advance, and this mixed solution may be charged into a pulper together with asbestos, cement, calcareous raw materials, and silicic raw materials. The slurry obtained as described above is temporarily stored in a chest, and the slurry in the chest is continuously supplied to the vat of the wet machine.

The slurry in the vat is removed by a papermaking cylinder,
This thin film is transferred to a felt-like belt with good water permeability,
It is wound up on a making roll. When the winding thickness of the making roll reaches a predetermined thickness (approximately 15 ribs), the rolled body is incised and peeled from the making roll, and then carried into a press.

Until this time, the raw original board has sufficient strength for cement mixing, and there is no deformation or damage to the raw original board. The raw original board is
Pressure is applied using the above press to dehydrate.

This pressing force is usually 60 to 140 k9/m. After dehydration, the green original plates are transported in a stacked state to a curing chamber, and this curing chamber is filled with atmospheric pressure steam for primary curing. This primary curing is for imparting strength to the green original plate to enable it to be cut, and after this primary curing, the original plate is cut into predetermined dimensions. This primary curing may be omitted if the original plate is not to be cut. Next, the original plates are carried into an autoclave in a stacked state, and the original plates are finally cured using high-temperature, high-pressure saturated steam.

Through this curing, the original plate is hardened by the hydration reaction of calcium silicate and the hydration reaction of cement.

In this case, the hydration reaction of calcium silicate is stopped before it forms tobermolite crystals, and the porosity of the product is kept sufficiently small. Moreover, the monocarboxylic acid light metal salt maintains water repellency without being melted or decomposed. Due to the low porosity and this twilling agent, a product with low water absorption can be obtained. Of course, no calcareous raw material remains (because it reacts with the silicic raw material to form calcium silicate hydrate, there is no free lime, and the occurrence of efforescence during use of the product can be prevented).

Furthermore, the synthetic fibers are kept in their original shape without melting or decomposing, giving the product sufficient impact resistance.

After curing in an autoclave as described above,
As mentioned above, the pressure inside the autoclave was temporarily returned to normal pressure, and then the pressure inside the autoclave was reduced to approximately 100 tons, and after this reduced pressure was maintained for approximately 1 hour, the lid of the autoclave was opened and the products were transported from the autoclave. do. The temperature of the product at the time of transport was approximately 5,000 ℃, and the moisture content was 15%. In the above example, the size of the autoclave is 50 mm, the plate dimensions are 45 medium length x 303 length x 11 willow thickness, and the capacity of the plate material in the autoclave is 1.
He is the father of 20. The second invention of the present application is mainly used for manufacturing asbestos cement boards.

In this second invention, one cycle of depressurization and reheating of the plate material with high-temperature and pressurized steam is performed between the curing process using an autoclave and the outsourced decompression cooling process, and a drying process is performed in which this cycle is repeated several times. inserted.

In the case of an autoclave of the above-described size, the second invention is carried out, for example, as shown in FIG. 2.

In this example, the high temperature
The high-pressure steam is saturated steam for curing (temperature of about 150
℃ and a pressure of 4 to 8 atmospheres), and the reduced pressure is about 100 sides Hg, as in the embodiment of the first invention.

The size of the autoclave in this embodiment is 100 square meters, the plate dimensions are 450 mm inside x 3030 ribs in length x 5 ribs in thickness, and the amount of plates stored in the autoclave is 240 squares.

Also in this Example of the second invention, the final plate temperature in the cooling process was about 5000, and the moisture content was 15%.

The method for manufacturing an inorganic plate material according to the present invention is the method described above, and has the following advantages.

{1) It is only necessary to add a vacuum system to the conventional autoclave equipment, and water vapor for curing can be used as the heating source. Therefore, equipment costs can be reduced. ■ Board materials can be uniformly cooled and dried.

Therefore, it is possible to prevent the plate material from warping. Glue The cooling rate can be adjusted by changing the decompression rate.

By setting the pressure reduction rate and pressure reduction value to predetermined values, the plate material can be cooled in a short time. '4} A constant state of drying is possible regardless of the season.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an autoclave apparatus used in the present invention, and FIG. 2 is an explanatory diagram showing an embodiment of the present invention. In the figure, 1 is an autoclave, 11 is an autoclave lid, 2 is a saturated steam supply pipe, 3 is a gas vent valve,
A is a vacuum system. 72 cupbearer＼fu

Claims (1)

[Scope of Claims] 1. After curing inorganic board material in a curing pot with high-temperature, high-pressure steam, the pressure inside the curing pot is reduced to a predetermined pressure of 1 atmosphere or less without opening the lid of the curing pot. A method for manufacturing an inorganic plate material, characterized in that the above-mentioned reduced pressure state is maintained until the temperature of the plate material reaches the boiling point temperature of water under the predetermined reduced pressure. 2. The method for manufacturing an inorganic plate material according to claim 1, wherein the predetermined reduced pressure is 300 to 50 mmHg, preferably 100 mmHg. 3. The method for manufacturing an inorganic board material according to claim 1 or 2, wherein the board material is a calcium silicate board material. 4. The method for producing an inorganic board material according to claim 3, wherein the calcium silicate board material is obtained by a papermaking method. 5 After curing the inorganic board material in a curing pot with high-temperature and high-pressure steam, the pressure inside the pot is reduced to a predetermined pressure of 1 atmosphere or less without opening the lid of the curing pot, and the board temperature is below the above-mentioned predetermined pressure. When the water temperature drops to near the boiling point of water, high-temperature, high-pressure steam is introduced into the pot again, and the above depressurization and supply of steam are repeated several times until the final depressurization state is reached until the plate material temperature is above A method for manufacturing an inorganic plate material, which comprises holding water under a predetermined reduced pressure until it reaches the boiling point temperature of water. 6. The method for manufacturing an inorganic plate material according to claim 5, wherein the predetermined reduced pressure is 300 to 50 mmHg, preferably 100 mmHg. 7. The method for manufacturing an inorganic board material according to claim 5 or 6, wherein the board material is an asbestos-cement board material. 8. The method for manufacturing an inorganic board material according to claim 7, wherein the asbestos-cement board material is obtained by a papermaking method.