JPS62260754A - Manufacture of gypsum board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an improved method of manufacturing gypsum board.

(Prior art) Conventionally, gypsum boards are made by adding an appropriate amount of water to calcined gypsum (β-type hemihydrate gypsum) to make a gypsum slurry, and if necessary, this gypsum slurry is mixed with l1ffi aggregate such as tIII waste, pearlite, harmukilite, or air. Add the foamed liquid foamed with aLt, and add adhesion aids such as oxidized starch, dextrin, and cellulose thread adhesive, setting accelerators such as potassium sulfate and iron sulfate, setting retardants such as glue, and sodium citrate as necessary. The gypsum slurry thus obtained is spread out between two sheets of base paper, and then moved over a forming belt made of flattened hair with a smooth surface.After the gypsum slurry is allowed to set and harden. The product is then cut into appropriate sizes and the excess moisture is removed by drying in a dryer.

(Problems with the prior art) When hemihydrate gypsum is hydrated, it sets and hardens to become dihydrate gypsum, but during this process it has the property of forming a three-dimensional structure.

Gypsum board takes advantage of this property, and is made of baked gypsum.
(If you add water to β-type hemihydrate gypsum to make gypsum slurry and spread it between two sheets of boat paper, the calcined gypsum will hydrate and change to dihydrate gypsum. , its] 昂(
At present, Bodo Hara is represented as Mr.

Therefore, the water content in the gypsum slurry is determined by the following reaction formula: Water [Theoretically, it is good if there are enough stars to complete the mouth, and the amount is 19 ff per 100 parts by weight of calcined gypsum.
This is part 1. Any more water than that has to be released from the stems as mentioned above, which results in a loss of 1.3 sacrificial energy.

Ca5O= ・1/21120 + 3/21120
- CaSO4.2HzO However, it is impossible to slurry calcined gypsum with such a moisture content.
Of course, liquidity cannot be provided either. In order to impart fluidity to the gypsum slurry so that it can be spread between two sheets of base paper, the amount of water in the gypsum slurry is usually 75 to 85 parts by weight per 100 parts by weight of calcined gypsum. This amount is several times the amount required for hydration of calcined gypsum.

(Hereinafter, 1 piece of calcined gypsum is required to obtain gypsum slurry.
The amount of water per 00 parts by weight is referred to as the amount of mixed water.

Further, hereinafter, parts by weight are simply referred to as parts. ) Using such a large amount of water results in a large loss of thermal energy, and reducing the amount of water mixed in as much as possible has been a long-standing challenge for gypsum board manufacturers. Therefore, attempts have been made to add surfactants to the gypsum slurry as water reducing agents, but the reality is that they have not been very effective.

As a result of extensive research over many years on a method for reducing the amount of mixed water while maintaining the fluidity of gypsum slurry, the inventors of the present invention discovered that, in order to obtain gypsum slurry, instead of adding water to calcined gypsum, water and small granules were added. They discovered that this is possible by using a mixture with ice, so-called ice water, and have completed the present invention.

(Means for Solving the Invention) That is, the method for manufacturing a gypsum board of the present invention involves adding a mixture of water and small water particles to calcined gypsum to form a gypsum slurry, and pouring the gypsum slurry between two sheets of board base paper. It is characterized by the ability to expand, especially when the particle size of small ice cubes is 1.
mm or less, and the ratio of water and small ice is 100% water.
600 parts or less, preferably 150 parts of small ice
550 copies or more.

(Specific conditions for carrying out the invention) The present invention will be explained in detail below.

In the present invention, calcined gypsum can be obtained by a known method.

That is, it can be obtained by calcining dihydrate gypsum at 1'40 to 170°C using a calcining furnace.

This is then added using a mixer to the calcined gypsum, a mixture of water and small water granules (ice water) and optionally iI! i cloud 1
Lightweight bone U such as scum, perlite, Nomarmukilite, etc.
Or a foaming liquid made by foaming with air, and if necessary, oxidized starch), dextrin, adhesion aids such as cellulose adhesives, setting accelerators such as potassium sulfate and iron sulfate, glue, sodium citrate, etc. The coagulating AF agent is added to a① to make a gypsum slurry. Next, apply this gypsum slurry to two
After spreading through the tote base paper, the gypsum slurry is allowed to set and harden. Once the setting and hardening is completed, it can be cut into appropriate dimensions and dried to produce a gypsum board.

When obtaining the gypsum slurry in the present invention, the amount of water added to the calcined gypsum and the mixture of small water particles (hereinafter referred to as ice water) is such that the gypsum slurry can be spread between two gypsum boards. Although the amount of water to be mixed is selected from 11 parts to 11 parts, the amount of water mixed in the present invention can be approximately 55 to 65 parts.

In the present invention, the size of the ice in the ice water is suitably 1 mm or less. If the size of the ice exceeds 11, the gypsum slurry will not completely turn into water after the completion of setting and hardening, but will remain in the form of a portion of water, which will melt during the drying process and then evaporate. This is undesirable because the part becomes hollow, and it also tends to lead to failure of the hydrated gypsum dihydrate (1 core of gypsum board) and the board base paper.

In the present invention, the ratio of water and small granular water in ice water is 600 parts or less of ice per 100 parts of water, preferably 50 parts or more of i-H5
It will be carried out in less than 50 copies. Water 7. If the amount exceeds 600 parts, it is impossible to obtain a good gypsum nulla'71-. In addition, when the particle size of water is large, two cavities are likely to occur in one gypsum board core, and poor adhesion between the gypsum board core and the board base paper is likely to occur. On the other hand, if the proportion of water is less than 150 parts, the amount of mixed water in the gypsum slurry must be increased to almost the same level as in the conventionally known method, and the effects of the present invention cannot be fully exhibited.

In the present invention, ice water is used to obtain the gypsum slurry, so it is necessary to slightly increase the amount of foaming liquid used to obtain the gypsum slurry. (If aggregate is used, it is necessary to also use a foaming liquid.) Furthermore, since the setting and hardening time of the gypsum slurry is slightly longer than in the conventional method, the amount of hardening accelerator used must be increased slightly accordingly. .

The gypsum board that has been set and hardened is cut into appropriate dimensions using a rotary cutter or the like, and then dried using a conventionally known dryer such as a tunnel dryer. Drying temperature is 120-16
Performed at 0°C.

(Preferred Mode for Carrying Out the Invention) The present invention will be specifically explained below using Examples and Comparative Examples. In addition, in Examples and Comparative Examples, % indicates weight %.

Implementation I + 1 After drying the dihydrate gypsum with adhering moisture of 22% as a by-product from the wet phosphoric acid factory to remove the adhering moisture, it was calcined in a calcining furnace at a continuous temperature of 6°C to produce 5L /h '7' Calcined gypsum was obtained.

Next, add 1OL/1OL of this calcined gypsum to a mixer with an effective volume of 8M.
h, 3200 kg/h of ice water at a ratio of 20 parts of water and 80 parts of water with a particle size of 0.5 to lim, 102 kg/h of Perley plaster as a lightweight aggregate, and a nonine-based interface made by Kao Sekiken/L Kiku as a foaming liquid. 15201/h of activator, 8 parts of 10% water, with air bubbled through it at 4 i/h; as an adhesion aid: 10% aqueous dextrin solution 7001h; as a curing accelerator, 5% aqueous solution of potassium sulfate; 3007 nights! /h was added to make a gypsum slurry. (The mixed water content of this gypsum slurry was 57 parts.) This gypsum slurry was spread between two sheets of base paper and spread on a forming heddle to a width of 910 m.
After the gypsum slurry had set and hardened, it was cut into lengths of 1820 to 1825 mm.

Next, this formed gypsum board is sent to a dryer and dried at a temperature of 130-155°C.
A product was obtained at 0 sheets/h. The steam used for drying at this time (
Saturated steam with gauge pressure 8Kg/c+d) is gypsum po 1
Each piece weighed 8.51 kg.

Comparative Example 1 The same method as in Example 1 was used except that water at room temperature (temperature 22°C) was used instead of the ice water of the present invention (however, the conditions for obtaining the gypsum slurry were as shown in Table 1). (Other conditions were the same as in Example 1) 1250 pieces/h of products were obtained. The amount of chaki used per 11 pieces of gypsum po is 13.32K.
It was g.

Table-1 (Note) The same foaming liquid as in Example 1 was used.

Example 2.3 Gypsum slurry was prepared under the conditions shown below (however, the 51 parts of ice water and water used in Example 2 was 30 parts of water and ice with a particle size of 0.3 to 1 ml). Proportion of 70 parts, Example 3
Example 1 except for the ratio of 40 parts of water to 60 parts of water with a particle size of 0.5 to 1 mm). ! :Product 1″f in the same way
is. Amount of Han Qi used per 11 pieces of Gypsum Po: 9.
They were 38Kg and 9.90Kg.

Table-2 (Note) The same foaming liquid as in δ Example 1 was used.

Comparative Example 2 Gypsum slurry was heated at room temperature (temperature 22°C) for 1-'f.
Using this water, 1250 pieces/h of products were obtained in the same manner as in Examples 2 and 3 (however, the conditions for obtaining the gypsum slurry were as shown in Table 3). 1 per plaster board
The amount of air used was 13.25 kg each.

Table-3 (Sho) G? & was the same as in Example 1.

(Effects of the Invention) As described in detail above, the present invention provides 5 types of gypsum boards made from baked gypsum. In contrast to the conventional method of using room-temperature water to obtain gypsum slurry, the present invention uses iced water, which is a very simple process change. As shown in the Examples and Comparative Examples, it has become possible to significantly reduce energy consumption, and as shown in the Examples and Comparative Examples, it has enabled large energy savings, and its economic effects are significant.

Claims (3)

[Claims] (1) A method for producing a gypsum board, which comprises adding a mixture of water and small ice particles to calcined gypsum to form a gypsum slurry, and spreading the gypsum slurry between two sheets of board base paper. (2) The method for manufacturing a gypsum board according to claim 1, wherein the small ice particles have a particle size of 1 mm or less. (3) Claim 1 in which the ratio of water and small ice particles is 600 parts by weight or less of small ice particles to 100 parts by weight of water.
The method for manufacturing a gypsum board according to item 1 or 2.