JPH01283137A - Light-weight gypsum plate - Google Patents

Abstract

PURPOSE:To obtain a light-weight gypsum plate having a strength and sufficient nonflammability as a refractory material by forming it of a gypsum layer of a foamable gypsum layer and a dense gypsum layer, forming the thickness of the foamable gypsum layer at a specific ratio of the whole layer thickness, and setting fiber contents of the foamable gypsum layer and the dense gypsum layer to the specific ratio of its gypsum. CONSTITUTION:A foamable gypsum layer is formed by adding surfactant, thickening agent, as required, to a slurry containing semiaqueous gypsum, water a reinforcing fiber as main ingredients, kneading the mixture, introducing a large quantity of bubbles and curing it. The dense gypsum layer is obtained, for example, by adding cake retarder and thickening agent, as required to paste containing semiaqueous gypsum, water and reinforcing fiber as main ingredients, and curing adjusted dense gypsum slurry. The thickness of the foamable gypsum layer is suitable set in a range of 50-95% of the whole thickness of the light-weight gypsum plate in view of its strength and light weight. The fiber used to reinforce the foamable gypsum layer and the dense gypsum layer includes inorganic fiber such as glass fiber, carbon fiber, asbestos, etc. or natural or synthetic organic polymer fiber. The mixing amount of the fiber is 10wt.% or less of the gypsum in view of reinforcement and moldability for both the foamable and dense gypsums.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a lightweight gypsum board, and more particularly to a lightweight gypsum board suitable for use as a fireproof covering material for steel frames, a fireproof partition material, a wall material for general construction, a ceiling material, and the like.

[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 the endothermic reaction caused by the dehydration of crystal water when heated and the heat insulation effect due to the large amount of air bubbles contained within the hardened body, it is widely used as a building material such as fireproof coatings for steel frames and fireproof partitions. It is used.

[Problems to be solved by the invention] Conventional lightweight gypsum boards have low strength because they are made of hardened gypsum that contains many air bubbles, and are prone to breakage during transportation or installation, or because the surface is brittle. There is a problem of peeling. In addition, since the surface is difficult to be smooth, the decorativeness of the surface is poor for use as a wall material.

The present invention solves the above conventional problems and provides a lightweight gypsum board that can provide a smooth and hard surface, has strength, and has sufficient noncombustibility as a fireproof material. purpose.

[Means for Solving the Problems] The lightweight gypsum board of the present invention is a lightweight gypsum hardened body formed of two gypsum layers: a cellular gypsum layer reinforced with fibers and a dense gypsum layer. The lightweight gypsum board according to claim 2, wherein the layer thickness is 50 to 95% of the total layer thickness, and the fiber content is 10% by weight or less of the gypsum in both the cellular gypsum layer and the dense gypsum layer. is one in which an organic coating is applied to the surface of the cellular gypsum layer and/or the dense gypsum layer.

The present invention will be explained in detail below.

Of the two gypsum layers constituting the lightweight gypsum board of the present invention, the cellular gypsum layer is made of a slurry mainly consisting of hemihydrate gypsum, water, and reinforcing 1#l fibers, and a surfactant and thickening agent as necessary. It is made by adding a chemical agent, kneading it, introducing a large amount of air bubbles, and curing it.

In this case, the method for introducing the bubbles may be either the preform method or the mix foam method.

In the preform method, first, a known foaming agent such as sodium alkyl sulfate, sodium alkylbenzene sulfonate, polyoxyethylene alkyl sulfate, etc. is added to gypsum hemihydrate in water.
．． Add 01 to 2.0% by weight and stir vigorously to foam. At this time, PVA (polyvinyl alcohol), Mc
When 0.05 to 3.0% by weight of a polymeric thickener such as (methylcellulose) is added to hemihydrate gypsum, stable bubbles are formed. This foamed water and hemihydrate gypsum 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.

Regardless of the bubble introduction method, the amount of water is preferably 40 to 100% by weight based on gypsum hemihydrate.

The specific gravity of the cellular gypsum layer obtained by curing such a slurry is preferably about 0.4 to 0.7.

The dense gypsum layer is obtained, for example, by curing a dense gypsum slurry prepared by adding a setting retarder and a thickener as necessary to a paste mainly consisting of gypsum hemihydrate, water, and reinforcing fibers. . Note that the amount of water relative to hemihydrate gypsum in the dense gypsum slurry is preferably 30 to 80% by weight.

As the setting retarder used in the dense gypsum slurry, known ones such as oxycarboxylic acid and its salts, gluconic acid and its salts, phosphoric acid and its salts, amino acids, and saccharides can be used, and the addition rate is as low as gypsum hemihydrate. 0.01 to 5.
0% by weight is preferred. In addition, polyvinyl alcohol, methyl cellulose, etc. can be used as a binder,
The addition rate thereof is preferably 0.1 to 3.0% by weight based on gypsum hemihydrate.

The setting control agent such as a setting retarder can be added not only to the dense gypsum slurry but also when preparing the cellular gypsum slurry.

The hemihydrate gypsum used as a raw material for both the cellular gypsum layer and the dense gypsum layer may be either α-type or β-type.

Examples of reinforcing fibers used for reinforcing the cellular gypsum layer and the dense gypsum layer include inorganic fibers such as glass fibers, carbon fibers, and asbestos, and natural or synthetic organic polymer fibers. As the glass fiber, it is preferable to use a weakly convergent fiber that is defibrated into monofilaments during slurry kneading, and specific examples of the organic polymer fiber include vinylon fiber and the like. These can be used alone or 2f!
A combination of the above can be used. Moreover, these reinforcing fibers can also be used in combination of long fibers and short fibers.

If the amount of such reinforcing fibers is too small, a sufficient reinforcing effect cannot be obtained, whereas if it is too large, moldability will deteriorate and the price of the product will increase, which is not preferable. Therefore, the amount of fiber blended in both the cellular gypsum layer and the dense gypsum layer is 10% by weight or less, preferably in the range of 0.5 to 5% by weight of the gypsum.

In the present invention, if the cellular gypsum layer is too thick and the dense gypsum layer is too thin, sufficient strength cannot be obtained;
On the other hand, if the cellular gypsum layer is too thin and the dense gypsum layer is too thick, the specific gravity of the gypsum board will increase and its lightness will be impaired. Therefore, the thickness of the cellular gypsum layer is appropriately set within the range of 50 to 95% of the total thickness of the lightweight gypsum board.

In the present invention, when applying an organic coating to the surface of the cellular gypsum layer and/or the dense gypsum layer, examples of the organic coating include paper, woven fabric, nonwoven fabric, leather, film, etc. made from natural or synthetic organic polymers. Among them, paper or nonwoven fabric can be particularly preferably used. Such an organic coating can be applied to either or both of the cellular gypsum layer and the dense gypsum layer, but in the present invention, it is preferable to cover at least the surface of the cellular gypsum layer with the organic coating. preferable. The aesthetic appearance can be improved by coloring or patterning these organic coatings.

An example of the method for manufacturing a lightweight gypsum board of the present invention will be described below with reference to the drawings.

FIG. 1 is a side sectional view showing an example of an apparatus suitable for manufacturing the lightweight gypsum board of the present invention, and FIG. 2 is a plan view thereof (however, the leveling belt is not shown in FIG. 2. ).

The apparatus shown in FIGS. 1 and 2 includes a horizontal belt 1 that is installed horizontally and runs horizontally, and an upper leveling belt 2 that runs horizontally above the horizontal belt 1. On the sides, side belts 3.3 are installed which run along the sides of the horizontal belt 1. In the figure, 11
12 is the driving roller of the horizontal belt 1, and 12 is the leveling belt 2.
13 is a driving roller for the side belt 3. Reference numeral 8 denotes side belt holding rollers installed at both ends of the horizontal belt 1 so that the side belt 3 runs at a fixed position on the end of the horizontal belt 1. Further, 4 is a lightweight gypsum board, 5 is a supply device for dense gypsum slurry A, 6 is a supply device for cellular gypsum slurry B, and 7 is an organic coating attached to the surface of the cellular gypsum layer.

The rollers 11, 12, and 13 are connected to a drive device (as shown in the figure) such as a variable speed motor, and the horizontal belt 1, leveling belt 2, and side belt 3.3 are driven synchronously, that is, at the same speed. It is said that it is possible to travel in the same direction. This drive device may be provided separately for each roller 11, 12, 13, or the rollers 11, 12, 13 may be connected to each other by a common drive source using an appropriate power transmission means such as a chain or a timing belt.
1.12.13 may be used to transmit ffi power.

To manufacture the lightweight gypsum board of the present invention using such an apparatus, first, the horizontal belt 1, leveling belt 2, and side belt 3.3 of the illustrated apparatus are driven at the same speed, and the horizontal belt 1 and the side belt 3.3 of the illustrated apparatus are driven at the same speed. In the recess formed by the side belt 3.3,
The dense gypsum slurry A that has been mixed in advance from the supply device 5 is
The aerated gypsum slurry B is supplied from the supply device 6, and if necessary, an organic coating 7 is sequentially supplied and laminated, and the upper leveling belt 2 is placed on top of the organic coating 7.

That is, the dense gypsum slurry A is supplied from the supply device 5 to the concave portion formed by the horizontal belt 1 and the side belts 3, 3 in the same thickness and sufficiently spread to the position of the side belts 3.3 at both ends. At the position where this slurry A has become slightly hardened, cellular gypsum slurry B is supplied from the supply device 6 onto the dense gypsum (slurry) layer 10a in the same manner.

Next, the organic coating 7 to be applied to the surface of the cellular gypsum (slurry) layer tob is supplied so as to be submerged between the upper surface of the cellular gypsum (slurry) layer 10b and the upper leveling belt 2, and the cellular gypsum (slurry) Paste it on the surface of PJlob.

Dense gypsum (slurry) layer 10a, aerated gypsum (slurry) layer tob, and organic coating 7 move in the recess formed by body belt 1 and side belt 3.3 while being leveled by upper leveling belt 2. . While performing this movement, the dense gypsum layer 10a and the cellular gypsum layer 10
b is cured and integrated, and an organic coating 7 is adhered to the cellular gypsum layer tob to produce the lightweight gypsum board 4 of the present invention. This lightweight gypsum board 4 is then cut into appropriate lengths and then dried in a drying process to form a product.

The upper leveling belt 2 has the function of adhering the organic coating 7 to the aerated gypsum (slurry) layer tob as described above, but when the organic coating 7 is not attached, it smoothes the upper surface of the aerated gypsum (slurry) layer 10b. It acts to make it even. Therefore, the upper leveling belt 2 is set to run in close contact with the upper surface of the cellular gypsum (slurry) layer tob or the organic coating 7. Further, the length needs to be long enough to allow the cellular gypsum (slurry) layer 10b to be in close contact with the belt for a period of time until it reaches a strength that does not require a mold. The side belts 3.3 also serve to make the side surfaces of the lightweight gypsum board a smooth surface.

In the apparatus shown in FIGS. 1 and 2, the position of the supply device 5.6 is changed so that the cellular gypsum slurry 81 and then the dense gypsum slurry A are supplied, thereby improving the surface of the dense gypsum layer. It is also possible to obtain one with an organic coating applied to it. Further, an organic coating sheet feeding device is provided upstream of the supply device 5, and an organic coating sheet,
By laminating the dense gypsum slurry, the cellular gypsum slurry, and the organic coating sheet in this order, a lightweight gypsum board with organic coatings on both sides can be obtained.

In addition, in the apparatus shown in the figure, it is possible to produce a cured product with good mold releasability even when the surfaces of the horizontal belt 1, leveling belt 2, and side belts 3.3 are left as they are. By coating with a resin or the like, adhesion between the plaster and the belt can be more reliably prevented, and the belt can be easily peeled off from the product, a lightweight plaster board, to obtain a lightweight plaster board with excellent surface smoothness. be able to.

According to the apparatus shown in FIGS. 1 and 2, the lightweight gypsum board of the present invention can be manufactured continuously with high production efficiency.

There is no particular restriction on the method for manufacturing the lightweight gypsum board of the present invention, and it is possible to manufacture it by other methods other than the above-mentioned apparatus. For example, the side surface of a board made of synthetic resin etc. First, pour dense gypsum slurry into a thin formwork surrounded by It can also be manufactured by placing an organic coating on the upper surface of the cellular gypsum layer and pressing the upper part with a roller or the like to apply the organic coating. In this case, by placing the organic coating in the formwork in advance, it is possible to obtain an organic coating that is also applied to the surface of the dense gypsum layer.

In the production of the lightweight gypsum board of the present invention, it is extremely important that the dense gypsum (slurry) layer and the cellular gypsum (slurry) layer come into contact with each other before they completely harden.

In other words, when a dense gypsum slurry and a cellular gypsum slurry come into contact with each other before they are completely hardened, at the interface between the cellular gypsum layer and the dense gypsum layer on the surface, the needle-shaped crystals of the two gypsums will touch each other. Since they grow and precipitate together in a cross-linked manner, a lightweight gypsum board with extremely strong bonding between both layers can be easily manufactured.

In the present invention, reinforcing fibers are blended into both the dense gypsum layer and the cellular gypsum layer that constitute the lightweight gypsum board. Even if you don't have it, you can still get some effect.

[Function] Since the - side of the lightweight gypsum board of the present invention is composed of a dense gypsum layer, the strength is improved compared to a conventional board composed of only a cellular gypsum layer. In addition, at least the surface of the dense gypsum layer is free from problems such as peeling, and the handleability is also good.

In particular, when the surface of the cellular gypsum layer is coated with an organic coating, damage to the cellular gypsum layer is prevented, and when both surfaces are coated with an organic coating, the strength can be further improved. By coloring or patterning this organic coating, it is possible to impart an excellent aesthetic appearance to the product and improve its decorative properties.

Example 1 100 parts by weight of β-hemihydrate gypsum was kneaded with 35 parts by weight of water, parts by weight of sodium citrate, 1 part by weight of methyl cellulose, and 1 part by weight of glass fiber to form a dense slurry A? : Prepared. Separately, cellular gypsum slurry B was prepared by kneading 100 parts by weight of β-hemihydrate gypsum, 80 parts by weight of water, 0.02 parts by weight of an anionic surfactant, and o and t parts by weight of polyvinyl alcohol. A lightweight gypsum board was produced using the apparatus shown in Figures 1 and 2 (however, no organic coating was applied).

That is, first, slurry A was supplied onto the horizontal belt 1 from the supply device 5, then slurry B was supplied thereon from the supply device 6, and the surface was leveled with the upper leveling belt 2. This operation was continuously performed. . As a result, a lightweight gypsum board with a smooth surface and a dense gypsum layer with a thickness of 5 mm and a cellular gypsum layer with a thickness of 50 mm could be continuously produced.

The obtained lightweight gypsum board was cut into a width of 600 mm and its physical properties were measured, and the bulk specific gravity was 0.69 and the bending strength was 3.
It was 2 kg f/c rn'.

Example 2 Using the slurry A and slurry B prepared in Example 1 and the nonwoven fabric C made of polyamide fibers, a lightweight gypsum board was manufactured using the apparatus shown in FIGS. 1 and 2.

First, slurry A was supplied onto the horizontal belt 1 from the supply device 5, and then slurry B was supplied thereon from the supply device 6. Furthermore, a nonwoven fabric C was supplied as an organic coating 7 so as to be hidden under the upper leveling belt 2. By continuously performing this operation, the thickness of the dense gypsum layer is 5 mm.
With a cellular gypsum layer thickness of 50 mm, it was possible to continuously produce a lightweight gypsum board in which a nonwoven fabric of polyamide fibers was attached to the surface of the cellular gypsum layer.

The resulting lightweight gypsum board was cut out to a width of 600 mm and its physical properties were measured; the bulk specific gravity was 0.68, and the bending strength was 3.
It was 5 kg f/cm'.

Note that the cellular gypsum layer and the nonwoven fabric were sufficiently adhered to each other.

[Effects of the Invention] As detailed above, the lightweight gypsum board of the present invention is a lightweight gypsum body with a two-layer structure of a dense gypsum layer and a cellular gypsum layer, and is lightweight and has excellent heat insulation, fire resistance, and sound insulation properties. In addition to its excellent properties, it has extremely high bending strength and excellent mechanical properties.

Moreover, by applying an organic coating, damage from the surface can be further reduced, and in this case,
It also has the advantage that decorativeness can be improved by coloring or patterning the organic coating.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view showing an example of a manufacturing apparatus suitable for manufacturing the lightweight gypsum board of the present invention, and FIG. 2 is a plan view thereof. 1...Horizontal belt, 2...Upper leveling belt, 3
...Side belt, 4...Lightweight plaster board, 5.6...
- Supply device, 7... Organic coating, A... Dense gypsum slurry, B... Cellular gypsum slurry. Representative Patent Attorney Tsuyoshi Shigeno

Claims (2)

[Claims] (1) A lightweight gypsum hardened body formed of two gypsum layers, a cellular gypsum layer and a dense gypsum layer reinforced with fibers,
A lightweight gypsum board characterized in that the cellular gypsum layer thickness is 50 to 95% of the total layer thickness, and the fiber content is 10% by weight or less of the gypsum in both the cellular gypsum layer and the dense gypsum layer. (2) The lightweight gypsum board according to claim 1, characterized in that an organic coating is applied to the surface of the cellular gypsum layer and/or the dense gypsum layer.