JPH04124055A - Hardened compact of lightweight gypsum - Google Patents

Abstract

PURPOSE:To provide a lightweight hardened compact of gypsum excellent in bending strength, surface hardness, smoothness, processability, etc., by preparing a construction in which a cellular gypsum layer is sandwiched between fiber-containing dense gypsum layers of a specific thickness through a prescribed amount of fiber bundles placed therebetween. CONSTITUTION:A fiber-containing hemihydrate gypsum slurry for the first layer is cast into a frame mold and the first fiber bundles are then oriented in the longitudinal direction. A cellular hemihydrate gypsum slurry for the second layer is subsequently cast and the second fiber bundles are then oriented in the longitudinal direction. A fiber-containing hemihydrate gypsum slurry for the third layer is subsequently cast and demolding is carried out after hardening the whole layers. The hardened compact is then dried. Thereby, the objective lightweight gypsum hardened compact containing the second layer, composed of the cellular gypsum layer containing fiber or without containing the fiber through the first and second fiber bundles interposed in an amount of 0.1-5wt.% based on the total weight of the lightweight gypsum hardened compact and sandwiched between the first and the third layers composed of fiber-containing dense gypsum layers having the total thickness of 10-50% based on the whole layer thickness from both sides is produced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a lightweight hardened gypsum body, and in particular to a steel fireproof coating material,
The present invention relates to an improved lightweight hardened gypsum body suitable for use in fireproof partition materials, etc.

[Prior Art] A lightweight cured gypsum body (multicellular gypsum board) manufactured by curing a gypsum slurry containing a large amount of air bubbles is not only lightweight, but also has non-combustibility, which is a characteristic of gypsum (two-piece gypsum). Due to its excellent fire-resistant properties, such as the endothermic reaction caused by dehydration of crystalline water when heated to 100°C or higher, and the heat insulation effect due to the large amount of air bubbles contained within the hardened body, it is used as a building material such as fire-resistant coating materials for steel frames and fire-resistant partition materials. It has been widely used as.

However, such a lightweight hardened gypsum body contains a large amount of air bubbles, so it has drawbacks such as low bending strength, a brittle surface that is difficult to handle, and a surface that is difficult to smooth.

For this reason, a method of covering the surface of a lightweight hardened gypsum board with paper or cloth has been proposed in the past (Japanese Unexamined Patent Publication No. 57-118).
144749), from the purpose of using lightweight hardened gypsum as a fireproof material in the event of a fire, using flammable or smoke-emitting materials such as paper or cloth will impede its properties as a fireproofing material, making it less advantageous. I can't say it's a method.

As a solution to the problems of conventional multicellular lightweight gypsum hardened bodies! A method for manufacturing a lightweight hardened gypsum body consisting of a three-layer laminated structure of a smuggling gypsum layer, a porous gypsum layer, and a dense gypsum layer has been proposed (Japanese Patent Laid-Open No. 63-24250
No. 3).

According to the method of JP-A No. 63-242503, the surface is smooth, hard, and has high bending strength, and it also has sufficient nonflammability as a fireproof material without using flammable or smoke-emitting materials. It is possible to continuously and efficiently manufacture a lightweight gypsum hardened body comprising:

[Invention tries to solve! ! However, when using lightweight hardened gypsum as fire-resistant building materials, there is always a desire for further improvement in its mechanical strength and durability.

The object of the present invention is to provide a lightweight hardened gypsum body which has further improved bending strength, etc., than the lightweight hardened gypsum body produced by the method of JP-A-83-242503.

[Means for Solving the Problems] The lightweight hardened gypsum body of the present invention consists of a porous gypsum layer containing tam or not containing fibers, and a dense gypsum layer containing fibers sandwiching this layer, and contains the Iia fibers! ! The total thickness of the smuggling gypsum layer is 10 to 50% of the total thickness of the light gypsum hardened body, and between the porous gypsum layer and the fiber-containing dense gypsum layer, there is a light gypsum hardened body. 0.1 to 5 of total body weight! ! % of fiber bundles are interposed therein.

The present invention will be explained in detail below.

The lightweight hardened gypsum body of the present invention has a multicellular gypsum layer containing fibers or not containing fibers (hereinafter referred to as "second layer") and a total thickness of the layers sandwiching this layer. 10
~50% fiber-containing dense gypsum layer (hereinafter referred to as "
It is sometimes referred to as the "first layer" and the "third layer." ) and fiber bundles in an amount of 0.1 to 5'% by weight of the total weight of the lightweight hardened gypsum sandwiched between the porous gypsum layer and the fiber-containing dense gypsum layer (
Hereinafter, these may be referred to as a "first fiber bundle" and a "second fiber bundle." ). Note that the fiber bundle may be provided only between the porous gypsum layer and either one of the first layer and the third layer of wA fiber-containing dense gypsum layer. In order to obtain a sufficient effect of improving strength and the like, it is preferable to provide a fiber bundle between the porous gypsum layer and the dense gypsum layer containing both fibers.

In the present invention, the 1 mm gold-containing smuggling gypsum layers forming both surfaces of the hardened body, that is, the first layer and the third layer, are mainly composed of gypsum hemihydrate and water, and preferably contain 0% of the raw gypsum hemihydrate.
．． It is formed by curing a slurry obtained by mixing 5 to 5% by weight of reinforcing fibers, and its specific gravity is generally 0.9 to 1.
This is a layer of illegally purchased gypsum containing about 100% of fiber. Note that a small amount of a known coagulation regulator can also be used in the slurry.

In the first and third layers, if the ratio of reinforcing fibers to the raw material gypsum hemihydrate is too small, processability may be impaired, and if it is too large, moldability may be impaired. Therefore, it is appropriate that the amount of fiber is within the above range. This th-
Examples of reinforcing fibers for the layers and the third layer include inorganic fibers such as glass fibers, and natural or synthetic organic polymer fibers.

As the glass fiber, one having weak convergence that can be woven into monofilaments in slurry mixed M# is suitable, and vinylon woven M etc. can be mentioned as a specific example of the organic polymer fiber.

If the thickness of the first layer and the third layer is too thin, moldability may be impaired, and on the other hand, if the thickness is too thick, the specific gravity of the cured product becomes large and lightness is impaired. Therefore, the total thickness of the first layer and the third layer is about 10 to 50% of the total thickness of the lightweight hardened gypsum body.

On the other hand, the central porous gypsum layer, that is, the second layer, is made by adding a known surfactant to a slurry mainly consisting of gypsum hemihydrate and water, or a slurry in which reinforcing fibers are mixed. It is a porous gypsum layer whose specific gravity is generally about 0.4 to 0.7. Note that a small amount of a known coagulation regulator can also be used in the slurry.

When reinforcing fibers are mixed into this second layer, the amount used is preferably about 0.3 to 5% by weight based on the raw material gypsum hemihydrate. As the reinforcing fibers used in the second layer, the reinforcing fibers used in the above-mentioned first and third layers can also be used.

As is clear from the comparison of the results of Example 1 and Example 2, which will be described later, in the present invention, the first fiber bundle and the first fiber bundle are used between the second layer and the second layer and between the second layer and the third layer. are inserted and reinforced, the bending strength necessary for the lightweight gypsum hardened product product is sufficiently ensured by the first fiber bundle and the second fiber bundle. Therefore, from the perspective of bulk specific gravity and bending strength,
Sufficient properties can be obtained even if the second layer does not contain reinforcing fibers, and in this case, the amount of reinforcing fibers used is smaller than when mixed in the entire layer, resulting in lower costs. but,
If reinforcing fibers are not mixed into the second layer, there is a drawback that the cut surface tends to become brittle when the lightweight hardened gypsum body is cut during construction. Therefore, the presence or absence of reinforcing fibers and the amount of reinforcing fibers to be mixed are appropriately determined depending on the intended use of the resulting lightweight hardened gypsum body.

The method for introducing air bubbles into the slurry for forming the multicellular gypsum layer may be either a preform method or a mix form method. In the preform method, first, a known foaming agent such as sodium alkyl sulfate, sodium alkylbenzenesulfonate, or polyoxyethylene alkyl sulfate is added to water in an amount of 0.02 to 2.0% by weight based on gypsum hemihydrate. Stir to foam. At this time, if 0.05 to 3.0% by weight of a polymeric substance such as PVA (polyvinyl alcohol) or MC (methyl cellulose) is added to the hemihydrate gypsum, stable bubbles can be formed. This foamed water and hemihydrate gypsum are mixed to form a slurry. Alternatively, 0.1 to 10 parts by weight of the foaming agent and 0.2 to 15 parts by weight of the thickener to 100 parts by weight of water! The mixed liquid and air are passed through a so-called foaming machine, which is a cylindrical container filled with beads or mesh, to generate foam. This foam, water, and gypsum hemihydrate are mixed to form a slurry. In the mix form method, materials with a similar composition are added at the same time and vigorously stirred to form a slurry. No matter which bubble introduction method is used, the amount of water is 40 to 1
00% by weight is preferred.

In the present invention, the gypsum hemihydrate used in the slurry for forming the first, second and third layers may be either α-type or β-type.

In addition, the fibers used for the fiber bundles, that is, the first fiber bundle and the second fiber bundle, include inorganic fibers such as glass fibers, or natural or synthetic organic polymer fibers, and specific examples of organic polymer fibers include vinylon. Examples include fibers. The fiber shape of this fiber bundle may be twisted or untwisted, but it is usually a roving, cord, or yarn of 460 to 880 fibers.
The number 0 is preferable. If the amount of these i*m bundles is too small, sufficient reinforcing effect will not be obtained, and if too much is used, separation will easily occur between the fiber-containing dense gypsum layer and the central porous gypsum layer. . Therefore, the amount of fiber bundle used is 0.1 to 5% by weight based on the total weight of the lightweight gypsum hardened body. The amount of mixed fiber bundles can be increased or decreased by changing the number and number of fibers in the fiber bundles used, the arrangement interval, etc.

In the present invention, the fiber bundles are preferably provided in an array extending in the longitudinal direction of the lightweight gypsum hardened body, but the direction of arrangement may be changed between the first fiber bundle and the second fiber bundle. In this case, the fiber bundles are made by bundling fibers with a diameter of about 1 to 5 mm that are approximately the same length as the lightweight hardened gypsum body to be manufactured, and are arranged extending in the longitudinal direction of the lightweight hardened gypsum body at intervals of 1 to 10 cm. It is preferable to provide the

To manufacture such a lightweight hardened gypsum body, first, a hemihydrate gypsum slurry mixed with the required fibers is poured into a mold. In this case, in order to make the surface of the first layer smooth, it is recommended to use a formwork with a bottom plate coated with plastic, a bottom plate covered with a plastic sheet, or a bottom plate made of mirror-polished metal. is advantageous. No.-
After pouring the required slurry, the first fiber bundles are arranged in the longitudinal direction, and then the aerated gypsum hemihydrate slurry for the second layer is poured. When casting the slurry for the first and second layers, a weak vibrator may be used for a short period of time to flatten the surface of the gypsum slurry. but,
It is not preferable to use this vibrator forcefully or for a long time because bubbles will rise upwards.

Next, when the second layer has become slightly stiff, the second fiber bundles are arranged in the longitudinal direction, followed by pouring the hemihydrate gypsum slurry for the third layer, covering it with a plastic sheet, and rolling it over it. , smooth the surface. In this way, by pouring the slurry of the next layer before the slurry of the previous layer has not completely hardened, the adjacent porous gypsum layer (second layer) and fiber-containing dense gypsum layer ( At the interface with the third or third layer, needle-shaped trihydrate crystals grow from one layer to the other and precipitate, creating an extremely strong bond between the two layers. A hardened gypsum body is easily produced. Thereafter, the lightweight gypsum cured body of the present invention is obtained by curing, demolding after full thickness hardening, and drying.

[Function] The lightweight hardened gypsum body of the present invention has a structure in which both surfaces of a porous gypsum layer reinforced with fiber bundles are further covered with fiber-containing dense gypsum layers, and are free from flammable or smoke-emitting substances. Because there is no coating with gypsum, the characteristics of the cured gypsum as a fireproof material are not impaired, and the bending strength is higher than that of a cured body made of only porous gypsum with the same bulk specific gravity. The bending strength is extremely high even compared to a cured product in which both surfaces of a cellular gypsum layer that is not reinforced with bundles are covered with fiber-containing dense gypsum layers. Moreover, the surface is hard and smooth. Therefore, it can be finished with paint or wallpaper, etc.
The adhesiveness of the wallpaper is also good.

[Examples] Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples unless it exceeds the gist thereof.

Example 1 1001i parts of β-hemihydrate gypsum, 65 parts by weight of water and 0.8 parts by weight of glass fibers were mixed in a Hobart mixer,
Slurry A was prepared. Separately, add 0.015 parts by weight of an anionic surfactant to 80 parts by weight of water and add o, i
parts by weight, stirred at high speed at 6000 rpm using a household mixer to foam, and 100 parts by weight of β-hemihydrate gypsum and 1.4 parts by weight of glass fibers were added and mixed to form multicellular gypsum slurry B. Prepared. Furthermore, the EH1110 glass roving was cut into a length of 24 cm to form a glass fiber bundle.

Pour slurry A to a thickness of 5 mm into a mold of 6 cm x 24 cm x 6 cm (thickness), and place 2 glass fiber bundles on top of it.
The books are arranged in parallel at 5cm intervals in the longitudinal direction, slurry B is injected to a thickness of 55mm, two glass fiber bundles are arranged on top of it in parallel at 5cm intervals in the longitudinal direction, and slurry A is injected to a thickness of 60mm. Injected, molded after hardening, 40
A lightweight hardened gypsum body was obtained by drying with ventilation at ℃ for 3 days.

The bulk specific gravity of this lightweight gypsum hardened body is 0.70 and the bending strength is 3.
It was 3 kgf/Cm'. The weight of the fiber bundle used was 0.37% by weight of the lightweight gypsum hardened body.

Example 2 Slurry A prepared in Example 1 was poured into a mold of 40 cm x 60 cm x 6 cm (thickness) to a thickness of 5 mm, and a glass fiber bundle (ER2310 glass roving with a length of 60 cm) was poured onto it. 8 pieces cut into pieces) were arranged in parallel at 5 cm intervals in the longitudinal direction, and then Example 1
The slurry B prepared in step 1 is injected to a thickness of 55 mm, and 8 glass fiber bundles with a length of 60 cm are placed on top of it by 5 cm in the longitudinal direction.
They were arranged in parallel at intervals of m, further injected with slurry A to a thickness of 60 mm, molded after curing, and dried with ventilation at 60° C. for 3 days to obtain a lightweight hardened gypsum body.

The bulk specific gravity of this lightweight gypsum hardened body is 0.68, and the bending strength is 3.
It was 0 kg f/cm2. The weight of the fiber bundle used was 0.23 mm% of the lightweight gypsum hardened body.

Comparative Example 1 Slurry A prepared in Example 1 was poured into a mold of 6 cm x 24 cm x 6 cm (thickness) to a thickness of 5 mm, slurry B prepared in Example 1 was poured on top of it to a thickness of 55 mm, and the slurry A was injected to a thickness of 60 mm, molded after curing, and dried with ventilation at 40° C. for 3 days to obtain a lightweight hardened gypsum body.

The bulk specific gravity of this lightweight gypsum hardened body is 0.70 and the bending strength is 2.
It was 1 kgf/am2.

Comparative Example 2 Slurry A prepared in Example 1 was poured into a mold of 40 cm x 60 cm x 6 cm (thickness) to a thickness of 5 mm, and slurry B prepared in Example 1 was poured to a thickness of 55 mm. The mixture was injected to a thickness of 60 mtn, molded after curing, and dried with ventilation at 60° C. for 3 days to obtain a lightweight hardened gypsum body.

The bulk specific gravity of this lightweight gypsum hardened body is 0.69 and the bending strength is 1.
It was 8 kgf/cm2.

Example 3 Slurry A prepared in Example 1 was poured into a mold of 40 cm x 80 cm x 6 cm (thickness) to a thickness of 5 mm, and 8 glass fiber bundles with a length of 60 cm similar to those used in Example 2 were placed on top of it. Slurry B prepared in Example 1 was further injected to a thickness of 55 mm, and 8 glass fiber bundles each having a length of 60 cm were arranged in parallel at 5 cm intervals in the longitudinal direction. and further add 6 slurry A.
The mixture was injected to a thickness of 0 mm, molded after curing, and dried with ventilation at 80° C. for 16 hours to obtain a lightweight hardened gypsum body.

The surface of this lightweight cured gypsum body was hard and smooth, and the wallpaper adhesiveness was extremely good.

From the above results, it is clear that the lightweight hardened gypsum body of the present invention has a significantly increased bending strength and a hard and smooth surface due to the reinforcing effects of the first fiber bundle and the second fiber bundle.

[Effects of invention As detailed above, the lightweight gypsum hardened body of the present invention is ■ High bending strength and excellent mechanical properties.

■ The surface is hard and smooth.

■ Therefore, it has excellent workability and can be applied well to painting and wallpaper finishing.

■ Since there is no coating of flammable or smoke-producing substances, the fire resistance of the plaster is not compromised.

It has excellent characteristics such as, and is extremely useful as a fire-resistant building material.

Claims (1)

[Claims] (1) Consisting of a cellular gypsum layer containing or not containing fibers and a dense gypsum layer containing fibers sandwiching this layer, the total thickness of the dense gypsum layer containing fibers is 10 to 50% of the total layer thickness.
A lightweight hardened gypsum body, in which a fiber bundle of 0.1 to 5% by weight of the total weight of the lightweight hardened gypsum body is interposed between the porous gypsum layer and the fiber-containing dense gypsum layer. A lightweight gypsum hardened body characterized by: