JPH08104578A - Lightweight gypsum hardened body - Google Patents

Abstract

PURPOSE: To improve the bond strength between a porous gypsum layer and a fiber-containing dense gypsum layer by interposing a net provided with an anchor or loop between the porous gypsum layer and the fiber-containing dense gypsum layer. CONSTITUTION: A porous gypsum slurry is obtained by adding 40-100wt.% water, 0.02-2.0wt.% foaming agent, 0.05-3.0wt.% polymer and if necessary, fiber into hemihydrate gypsum, strongly stirring to foam. A hemihydrate gypsum slurry containing fiber is poured into a molding flask and after that, the net 1 provided with the anchors or loops 1a, 2a on both front and rear surfaces is arranged so as to make it 0.1-5wt.% of total weight of a lightweight gypsum hardened body. Next, the porous gypsum slurry is poured thereon and hardened to obtain the lightweight gypsum hardened body composed of the porous gypsum layer, the net and the fiber-containing dense gypsum layer having thickness of 10-50% of the whole layer thickness.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lightweight gypsum cured product,
In particular, it relates to an improved light-weight gypsum hardened product suitable for use in steel frame fireproof coating materials, fireproof partitioning materials, and the like.

[0002]

2. Description of the Related Art A light weight gypsum hardened product (multi-foam gypsum board) produced by hardening a gypsum slurry containing a large amount of air bubbles, together with its lightness, is non-combustible, which is a characteristic of gypsum (dihydrate gypsum), Building materials such as steel frame fireproof covering materials and fireproof partitioning materials due to their excellent fire resistance such as endothermic reaction by dehydration of crystal water when heated to 100 ° C or more, and heat insulation effect due to a large amount of bubbles contained in the hardened body. Has been widely used since then.

A method for producing a light-weight gypsum hardened product having a three-layer laminated structure of a dense gypsum layer, a multi-foamed gypsum layer and a dense gypsum layer has been proposed as a light-hardened multi-gypsum cured product (Japanese Patent Application Laid-Open No. 2000-242242). 63-242503).

According to the method disclosed in Japanese Patent Laid-Open No. 63-242503, the surface is smooth and hard, has a high bending strength, and is sufficient as a fireproof material without using a flammable or fuming material. It is possible to continuously and efficiently manufacture a light-weight gypsum hardened product having excellent noncombustibility.

Further, it is composed of a multi-foam gypsum layer containing fiber or no fiber and a fiber-containing dense gypsum layer sandwiching the layer, and the total thickness of the fiber-containing dense gypsum layer is 10 to 10% of the total layer thickness. A lightweight gypsum cured product of 50%, wherein a net of 0.1 to 5 wt% of the total weight of the lightened gypsum cured product is interposed between the multi-foam gypsum layer and the fiber-containing dense gypsum layer. A light-weight gypsum hardened product has been proposed by the present applicant (Japanese Patent Application No. 2-292681; hereinafter referred to as "prior application").

The light-weight gypsum hardened product of the prior application has a structure in which both surfaces of a multi-cellular gypsum layer reinforced on both sides with a net are further covered with a dense gypsum layer containing fibers, which is a flammable or smoke-producing substance. Since there is no coating by, the characteristics of the cured gypsum as a refractory material are not impaired, and the bending strength is higher than that of a cured product of only the foamy gypsum of the same bulk specific gravity, and the net of the same bulk specific gravity Even when compared to a hardened body in which both surfaces of a multi-cellular gypsum layer not reinforced with are coated with a fiber-containing dense gypsum layer,
Bending strength is very high. Moreover, the surface is hard and smooth.
Therefore, it can be directly painted or finished with wallpaper or the like, and the adhesiveness of the wallpaper is good.

[0007]

DISCLOSURE OF THE INVENTION The present invention provides a light-weight gypsum hardened product in which the bondability (peel strength) between the multi-foam gypsum layer and the dense gypsum layer in the light-weight gypsum hardened product of this prior application is enhanced. With the goal.

[0008]

The light-weight gypsum hardened product of the present invention is the light-weight gypsum hardened product of the above-mentioned prior application in which an anchor or loop is provided on the net.

[0009]

In the light-weight gypsum hardened product of the present invention, the anchor or loop anchors into the gypsum layer by the anchoring effect,
The bonding strength between the net and the gypsum layer is increased, and the bonding strength between the dense gypsum layer and the multi-cellular gypsum layer is improved.

Hereinafter, the present invention will be described in more detail.

The light-weight gypsum hardened product of the present invention has a total thickness sandwiched between a multi-foam gypsum layer containing fibers or no fibers (hereinafter referred to as "second layer"). Fiber-containing dense gypsum layer (hereinafter, these may be referred to as "first layer" and "third layer") in an amount of 10 to 50% of the layer thickness, a multi-cellular gypsum layer and a fiber-containing dense gypsum layer 0.1 to 5% by weight of the total weight of the cured light weight gypsum sandwiched between the layers
Quantity net (hereinafter, these may be referred to as "first net" and "second net"). The mesh may be provided only between the multi-cellular gypsum layer and one of the first and third fiber-containing dense gypsum layers, but the bending strength, etc. In order to make the improvement effect of the above sufficient, it is preferable to provide a mesh between the multi-foam gypsum layer and both fiber-containing dense gypsum layers.

In the present invention, the fiber-containing dense gypsum layers forming both surfaces of the hardened product, that is, the first layer and the third layer, are mainly composed of hemihydrate gypsum and water. On the other hand, it is a dense fiber-containing gypsum layer formed by curing a slurry obtained by mixing 0.5 to 5% by weight of reinforcing fibers, and generally having a specific gravity of about 0.9 to 1.1. A small amount of known coagulation regulator may be used in the slurry.

In the first and third layers, if the ratio of the reinforcing fiber to the raw material hemihydrate gypsum is too small, the workability may be impaired, and conversely, if it is too large, the moldability may be impaired. Therefore, it is appropriate that the fiber amount is in the above range. Examples of the reinforcing fibers of the first layer and the third layer include inorganic fibers such as glass fibers and natural or synthetic organic polymer fibers. As the glass fiber, one that is weakly converged so as to be disintegrated into a monofilament at the time of kneading the slurry is preferable, and as a specific example of the organic polymer fiber, vinylon fiber or the like can be mentioned.

If the thickness of the first layer and the third layer is too thin, the moldability and strength may be impaired, and conversely, if the thickness is too thick, the specific gravity of the cured product will be large and the lightness will be impaired. Therefore, the total thickness of the first layer and the third layer is about 10 to 50% of the total thickness of the light-weight gypsum cured product.

On the other hand, the central multi-foam gypsum layer, that is, the second layer, is prepared by adding a known surfactant to a slurry mainly composed of hemihydrate gypsum and water or a slurry in which reinforcing fibers are further mixed, It is formed by introducing a large amount of bubbles and curing it, and its specific gravity is generally 0.4 to 0.7, which is a multi-foam gypsum layer. A small amount of known coagulation regulator may be used in the slurry. When reinforcing fibers are mixed and used in this second layer, the amount used is 0.3 with respect to the raw material hemihydrate gypsum.
It is preferably about 5% by weight. As the reinforcing fiber used for the second layer, the reinforcing fiber used for the first layer and the third layer described above can be used.

In the present invention, since the first net and the second net are inserted and reinforced between the first layer and the second layer and between the second layer and the third layer, it is necessary for the light-weight gypsum hardened product of the product. The bending strength is sufficiently secured by the first net and the second net. Therefore, from the viewpoints of bulk specific gravity and bending strength, sufficient properties can be obtained without including reinforcing fibers in the second layer. In this case, the amount of reinforcing fibers used is less than that in all layers. Since only a small amount is required, the cost will be lower. However, when the reinforcing fiber is not mixed in the second layer, there is a drawback that the cut surface is easily fragile when the light-weight gypsum hardened body is cut during construction. Therefore, the presence or absence of the reinforcing fibers and the amount of the reinforcing fibers are appropriately determined depending on the purpose of use of the obtained lightened gypsum cured product.

The method of introducing air bubbles into the slurry forming the multi-cellular gypsum layer may be either a preform method or a mixed foam method. In the preform method, first, a known foaming agent such as sodium alkyl sulfate, sodium alkylbenzene sulfonate, and polyoxyethylene alkyl sulfate is added to water in an amount of 0.02 to 2.0% by weight based on hemihydrate gypsum,
Stir vigorously to foam. At this time, when high molecular substances such as PVA (polyvinyl alcohol) and MC (methyl cellulose) are added to the hemihydrate gypsum in an amount of 0.05 to 3.0% by weight, 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 above foaming agent and 0.2 parts of a thickening agent are added to 100 parts by weight of water.
The liquid mixed with ˜15 parts by weight and air are passed through a so-called foaming machine in which beads or mesh are filled in a cylindrical container to generate bubbles. The foam, water and hemihydrate gypsum are mixed to form a slurry. In the mixed foam method, materials are simultaneously added with the same composition and stirred vigorously to form a slurry. Whatever the method of introducing bubbles, the amount of water is preferably 40 to 100% by weight with respect to the hemihydrate gypsum.

In the present invention, the hemihydrate gypsum used in the slurry for forming the first layer, the second layer and the third layer is α type,
Either β type may be used.

As the fibers constituting the net, that is, the first net and the second net, there are inorganic fibers such as glass fibers and natural or synthetic organic polymer fibers. Specific examples of the organic polymer fibers are as follows. Examples thereof include vinylon fiber. When the amount of the mesh composed of these fibers is too small, a sufficient reinforcing effect cannot be obtained, and conversely, when the amount is too large, peeling occurs between the fiber-containing dense gypsum layer and the central foamy gypsum layer. It is easy to wake up. Therefore, the amount of the net used is 0.1 to 5% by weight based on the total weight of the cured light weight gypsum. The amount of mesh inclusion can be increased or decreased by changing the count or opening of the fibers forming the mesh. If the mesh is too wide, the fibers used in the mesh will become thick and the formability will deteriorate. Further, if it is narrow, peeling easily occurs between the fiber-containing dense gypsum layer and the central multi-cellular gypsum layer. Therefore, the mesh opening is 2 mm to 30 m
A value of m is suitable.

The network is provided with anchors or loops.

FIGS. 1 to 5 are configuration diagrams of the network, in which (a) is a plan view of the network and (b) is a side view.
The nets 1 and 2 in FIGS. 1 and 2 are provided with L-shaped anchors 1a and 2a.

In FIG. 1, anchors 1a are projected from the same portion of the net on both the front and back sides of the net, and in FIG. 2, anchors 2a are projected from the different locations on the front and back of the net.

Although not shown, J-shaped or T-shaped anchors may be provided.

The net 3 of FIG. 3 comprises a straight anchor 3a. The anchors 3a are projected from different positions on the front and back of the net 3, but may be projected from the same positions on the front and back as shown in FIG.

The net 4 shown in FIG. 4 has loops 4a continuously appearing alternately on the front and back of the net.

In the net 5 shown in FIG. 5, independent loops 5a are provided every other mesh opening. The number and arrangement of loops may be other than those shown.

Although not shown, a net provided with both loops and anchors can also be used.

In order to produce such a light-weight gypsum hardened product, first, a fiber-containing hemihydrate gypsum slurry for the first layer is poured into a mold. In this case, as the mold, in order to make the surface of the first layer smooth, a bottom plate coated with plastic,
Alternatively, it is advantageous to use a bottom plate provided with a plastic sheet or a mold having a mirror-polished metal bottom plate. After pouring the slurry for the first layer, the first net is arranged, and subsequently, the bubble-containing hemihydrate gypsum slurry for the second layer is poured. In casting the first and second layer slurries, a weak vibrator may be used for a short time to even out the surface of the gypsum slurry. However, the use of this vibrator is not preferable because the bubbles rise upward when it is used strongly or for a long time.

Next, a second net is arranged, and then the hemihydrate gypsum slurry for the third layer is poured in and the surface is smoothed by a method such as rolling from above. In this way, by pouring the slurry of the next layer before the slurry of the layer poured in before is not completely hardened yet, the adjacent foamed gypsum layer (second layer) and the fiber-containing dense gypsum layer ( At the interface with the first layer or the third layer), needle-shaped crystals of gypsum dihydrate grow from one layer to the other layer and precipitate, so that the bond between the two layers is extremely strong. A cured product is easily manufactured. After that, the light-weight gypsum cured product of the present invention is obtained by curing, removing the mold after curing all layers, and drying.

By the continuous manufacturing method, the first layer is formed on the belt conveyor, the net is placed on the first layer, the second layer is formed, and then the net is placed and then the third layer is formed. Can produce the light-weight gypsum hardened product of the present invention.

[0031]

EXAMPLES The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples unless it exceeds the gist.

Example 1 Slurry A was prepared by mixing 65 parts by weight of water and 0.8 parts by weight of glass fiber with 100 parts by weight of β-hemihydrate gypsum in a Hobart mixer. Separately, 0.015 parts by weight of an anionic surfactant and 0.1 part by weight of PVA were added to 80 parts by weight of water, and the mixture was agitated at high speed at 6000 rpm with a household mixer to produce β-semi-water. 100 parts by weight of gypsum and 1.4 parts by weight of glass fiber were added and mixed to prepare a foamy gypsum slurry B. Further, the size was 6 × 24 cm, the opening was 5 mm, and 200 g / m ² , and ^two glass fiber nets shown in FIG. 1 were prepared. The dimensions of this net are shown in FIG.

Slurry A was poured into a mold of 6 cm × 24 cm × 6 cm (thickness) to a thickness of 5 mm, one glass net was laid on it, and then slurry B was poured to a thickness of 55 mm, and then, A piece of glass net was laid on it, and the slurry A was further injected to a thickness of 60 mm, and after curing, the mold was removed from the mold, and dried at 40 ° C. for 3 days with ventilation to obtain a cured lightweight gypsum body.

The light-weight gypsum cured product had a bulk specific gravity of 0.65 and a bending strength of 45 kgf / cm ² . Also, first,
The peel strength between the two layers and the second and third layers is 4.50 kgf /
cm ² . The net weight used was 1.0% by weight of the light weight gypsum cured product.

In order to measure the peel strength, a groove having a depth of 15 mm is provided vertically and horizontally on the surface of the light-weight gypsum hardened product so as to have a grid shape of 10 cm on a side, and 10 cm × 1 on each grid.
An iron plate having a size of 0 cm is adhered with an adhesive, and the iron plate is pulled up perpendicularly to the plate surface of the light-weight gypsum hardened product, and a pulling load is applied when peeling occurs between the first layer or the third layer and the second layer. I tried to ask.

Examples 2 to 5 Lightweight gypsum hardened bodies were produced in the same manner as in Example 1 except that the nets shown in FIGS. 2 to 5 were used.

Table 1 shows the bulk specific gravity, flexural strength, and peel strength of the first, second and second and third layers of each light-weight gypsum cured product.

Comparative Example 1 A light-weight gypsum cured product was obtained in the same manner except that a mesh having an opening of 5 mm and having no anchor or loop (that is, the structure excluding the anchor 1a in FIG. 1) was used.

The bulk specific gravity, bending strength, and
Table 1 shows the peel strengths of the first and second layers and the second and third layers.

[0040]

[Table 1]

As is clear from Table 1, according to the present invention,
The peel strength of the first, second and second and third layers is extremely high,
Further, a light-weight gypsum hardened product having high bending strength is produced.

The surface of each of the light-weight gypsum hardened products was hard and smooth, and the adhesiveness to wallpaper was extremely good.

[0043]

As described in detail above, the light-weight gypsum cured product of the present invention has extremely high peel strength between the dense gypsum layer and the multi-cellular gypsum layer. It has extremely high bending strength and excellent mechanical properties. The surface is hard and smooth. Therefore, the workability is excellent, and the painting and the wallpaper finish can be performed well. Since there is no coating of flammable or fuming substances, the fire resistance of gypsum is not impaired. It has excellent features such as, and is extremely useful as a fire resistant building material.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a network 1 used in an embodiment.

FIG. 2 is a configuration diagram of a network 2 used in the embodiment.

FIG. 3 is a configuration diagram of a network 3 used in the embodiment.

FIG. 4 is a configuration diagram of a network 4 used in the embodiment.

FIG. 5 is a configuration diagram of a network 5 used in the embodiment.

[Explanation of symbols]

 1,2,3,4,5 Network 1a, 2a, 3a Anchor 4a, 5a Loop

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication C04B 28/14 // (C04B 28/14 16:12) 111: 40 (72) Inventor Hideo Yukawa 1-297 Kitabukuro-cho, Omiya City, Saitama Prefecture Cement Research Institute, Mitsubishi Materials Corporation

Claims (1)

[Claims] 1. A multi-cellular gypsum layer containing fibers or no fibers, and a dense gypsum layer containing fibers sandwiching the layer, wherein the total thickness of the dense gypsum layers containing fiber is 10 of the total layer thickness.
A lightweight gypsum hardened product having a content of ˜50%, wherein a net of 0.1 to 5% by weight of the total weight of the lightened gypsum hardened product is present between the multi-foam gypsum layer and the fiber-containing dense gypsum layer. A cured light-weight gypsum characterized in that an anchor or a loop is provided on the net.