JPS599325B2 - Manufacturing method of fiber sheet reinforced foam gypsum panel - Google Patents

Description

Detailed Description of the Invention (Summary) The present invention provides a gypsum-impregnated sheet in which an organic or inorganic fiber sheet is impregnated with a mixed slurry of a water-soluble emulsion such as vinyl acetate, acrylonitrile, or urea resin and hemihydrate gypsum. It relates to a method for manufacturing a fiber sheet-reinforced foamed gypsum panel, which is formed by inserting the foamed gypsum slurry between the upper and lower two layers and drying it.

(Prior art) Conventionally, inorganic fiber sheets such as glass fibers and rock wool have been brought into direct contact with gypsum slurry in the normal gypsum board manufacturing process to produce noncombustible gypsum boards. This was considered almost impossible due to the nature of the surface.

In other words, these inorganic fiber sheets, such as glass fiber, have coarse fibers that allow water to pass through and are not compatible with water, and rock wool, which has extremely high water absorbency and can be locally dehydrated. It is generally known that the adhesion between inorganic fibers and gypsum slurry deteriorates due to such phenomena.

As a countermeasure for this, as stated in Japanese Patent Publication No. 50-7615, a gypsum slurry mixed with an emulsion of vinyl acetate, polyvinyl alcohol, etc. is poured between inorganic fiber sheets, or an inorganic fiber sheet is inserted inside the slurry. At the very least, there is a lot of talk about molding and drying, but the adhesion between the inorganic fiber sheet and the plaster is not necessarily sufficient, and it has not yet been commercialized.

(Purpose) The present invention involves impregnating an organic or inorganic fiber sheet with a gypsum slurry to which a resin emulsion such as vinyl acetate has been added in advance, and inserting the sheet between two foamed gypsum slurry layers to form a fiber sheet. An object of the present invention is to provide a method for manufacturing a fiber sheet-reinforced foamed gypsum panel that has tight adhesion between the foamed gypsum and the foamed gypsum panel.

(Structure) First, the present inventor prepared a mixed slurry of a water-soluble emulsion such as vinyl acetate resin, acrylonitrile resin, or urea resin alone or a mixture of two or more of them and hemihydrate gypsum slurry on an organic or inorganic fiber sheet. By making a gypsum-impregnated sheet impregnated with the foamed gypsum slurry, inserting it inside the foamed gypsum slurry layer, and molding and drying it, the adhesion between the fiber sheet and the foamed gypsum slurry is significantly improved, and warping is prevented. We have discovered that it is possible to produce a noncombustible, lightweight gypsum panel that has good bending strength, good nailability, and no cracking.

That is, an emulsion of vinyl acetate, acrylonitrile, urea, etc., singly or in combination of two or more, is added to a hemihydrate gypsum slurry normally used for manufacturing gypsum board, and stirred rapidly to form a mixed slurry. A thin organic or inorganic fiber sheet is immersed in it.

Then, the mixed slurry adsorbs and fills the gaps between the fiber sheets and solidifies over time, completing a gypsum-impregnated sheet. Next, this gypsum-impregnated sheet is inserted inside the foamed gypsum slurry layer to make a panel.To explain the outline of this process with reference to the drawings, first, the board cover 2 is placed on the conveyor 1 and moved in the direction of the arrow. Next, a foamed gypsum slurry 3 obtained by mixing foam into a gypsum slurry and rapidly stirring it in a mixer is added to the board cover 2.
After pouring the foamed gypsum slurry 5 on top of the slurry and spreading it evenly, placing the aforementioned gypsum-impregnated sheet 4 on top of it and pouring the foamed gypsum slurry 5 again on top of it and spreading it evenly on the sheet 4, Finally, it is covered with a board backing paper 6 and formed into a panel using a forming roll 7. The panels formed in this manner are transported by a conveyor, cut into predetermined lengths, and transferred to a drying process as soon as the plaster finishes curing. In the panel thus obtained, good gypsum crystals thickened by the resin emulsion grow, which intricately penetrate into the coarse lattice of the fiber sheet, and are then integrally bonded to the upper and lower two foamed gypsum layers. Therefore, as a whole, it is possible to obtain a good panel in which the fiber sheet and the foamed gypsum are completely adhered to each other. The amount of emulsion such as vinyl acetate used in the present invention varies depending on the manufacturing conditions of hemihydrate gypsum, the thickness of the organic or inorganic fiber sheet, the conditions for manufacturing foamed gypsum slurry, etc. 3 to 5 per 100 parts of hemihydrate gypsum
A small amount of water is sufficient.

In addition, the inorganic fiber sheet used in the present invention refers to glass fiber, rock wool, asbestos paper, etc., and the organic fiber sheet refers to natural fiber woven fabric such as cotton or hemp, or polyvinyl alcohol, A woven fabric or non-woven fabric sheet made of synthetic fibers such as polynosik.

(Effects) As mentioned above, the fiber sheet-reinforced foamed gypsum panel obtained by the present invention has excellent adhesion between the foamed gypsum and the gypsum-impregnated sheet, has high bending strength, is lightweight, has good nailing properties, and is noncombustible. This makes it possible to manufacture gypsum boards.

Further, in carrying out the present invention, the blending of the various resin emulsions and the gypsum slurry is carried out during a normal gypsum slurry preparation process without requiring almost any special equipment, so the process is extremely simple. The panel selected according to the present invention has the above-mentioned excellent properties and has a beautiful surface, so its utility value is extremely high for noncombustible ceiling materials and various other building materials. Examples will be described below.

All compounding ratios indicate parts by weight. Example 1 250 parts of hemihydrate gypsum and 150 parts of water were added, stirred, then 50 parts of vinyl acetate emulsion was added, and a glass fiber sheet with a thickness of 0.3 to 1.07X1 was immersed in the slurry made by stirring thoroughly. After thoroughly impregnating with slurry, it is pulled up.

It is then compressed to remove excess slurry. After several tens of minutes, the sheet hardens and becomes a gypsum-impregnated sheet. Meanwhile, 20 parts of rosin soap (10% solution) and 1 part of glue (5% solution)
A composition consisting of 0 parts, 30 parts of water, and 40 parts of vinyl acetate emulsion (50% solution) is placed in a mixer and stirred for 1 minute to obtain a fine foam.

Next, the above-mentioned foam was added to a gypsum slurry obtained by stirring 200 to 300 parts of hemihydrate gypsum and 200 parts of water, and the foam was further rapidly stirred. Gypsum boards were manufactured using slurries 3 and 5 according to the manufacturing method described above, and panels with a thickness of 12 to 15 mm were manufactured.

The density of the obtained panel was 0.3 to 0.5, and the adhesion between the glass fiber sheet and the plaster was extremely good.
No warpage was observed, and the nailing performance was extremely good.

Example 2 250 parts of hemihydrate gypsum, vinyl acetate emulsion (50 parts)
% solution), 25 parts of urea resin (Konishi K.K. Euroid 22), and 150 parts of water were thoroughly mixed to prepare a uniform slurry.

A glass fiber sheet with a thickness of 0.3 to 1.0 mm was immersed in this solution, and after being thoroughly impregnated with the slurry, the thickness was 12 m as in Example 1 above! panels were manufactured.

The density was 0.3 to 0.5, and the adhesion between the glass fiber and the plaster was very good, there was no warping at all, and the nailing performance was also very good.

For reference, a sample with a thickness of 1 was manufactured in the same manner as above, except that the glass fiber sheet was not immersed in gypsum.
The 2 m1 panel cracked at the slightest impact after drying, and the foamed gypsum on the glass fiber sheet flaked off, indicating poor adhesion to the gypsum.

The panel of the present invention showed no abnormality at all when subjected to similar impact.

Although the panel of this embodiment has paperboard pasted on the front and back sides, if necessary, it is possible to omit the paperboard and produce a panel with the plaster surface exposed.

In this case, release paper is used instead of board paper.

[Brief explanation of drawings]

The drawing is a schematic diagram of an apparatus according to the manufacturing method according to the invention. 1: Conveyor 1, 2: Cover for board, 3: Foamed gypsum slurry 4: Gypsum-impregnated sheet, 5: Foamed gypsum slurry 6: Backing paper for board, 7: Molding roller.

Claims (1)

[Scope of Claims] 1. A gypsum-impregnated sheet in which an organic or inorganic fiber sheet is impregnated with a mixed slurry of a water-soluble emulsion such as vinyl acetate resin, acrylic resin, or urea resin, alone or as a mixture, and hemihydrate gypsum. A method for producing a fiber sheet-reinforced foamed gypsum panel, which is characterized in that this is inserted between two upper and lower foamed gypsum slurry layers, and then molded and dried. 2. The method for producing a fiber sheet-reinforced foamed gypsum panel according to claim 1, wherein the organic or inorganic fiber sheet is a glass fiber sheet.