JP2920016B2 - Method for producing gypsum board for high-strength building materials using papermaking pulp sludge - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recycling paper pulp sludge which has been conventionally disposed of as industrial waste by incineration or landfill. In particular, the present invention relates to a method of mixing paper pulp sludge and gypsum. The present invention relates to a method for producing a pulp sludge gypsum board for a high-strength building material having high strength, excellent dimensional stability, excellent nailing adhesion, high sound absorption, and low thermal conductivity by pressure molding.

[0002]

2. Description of the Related Art Conventionally, papermaking pulp sludge has been disposed of in landfills. However, it is becoming increasingly difficult to secure landfills, and the importance of reusing them is regarded as important. As one of the methods of reuse, it has been proposed to regenerate as a building material, particularly as a gypsum board for a building material. As a method of manufacturing a gypsum board for building materials using papermaking pulp sludge, a papermaking pulp sludge is added with 1-30 mm long fiber such as glass wool, cellulose fiber, synthetic fiber, etc., mixed with gypsum, and pressure molded. (Japanese Patent Application Laid-Open Nos. 50-95320 and 50-9532) have been proposed.
2 etc.). For example, JP-A-50-95322 discloses
Special board for building materials characterized by mixing 1-30mm long fiber material and gypsum with drainage sludge consisting of fine organic fiber and mineral matter derived in paper and pulp manufacturing process, press molding and drying Are disclosed. Here, it is described that in order to obtain the most functional entanglement of sludge, gypsum and long-fiber material, the kneading-squeezing operation yields excellent properties, and particularly that squeezing is useful for entanglement. .

[0003]

According to this method, a long fiber is added as a reinforcing material to paper pulp sludge, and thereby the gypsum and the fiber are entangled with each other, thereby improving the strength at the time of molding. It is based on that. However, in this proposed method, in the obtained product, the binding force between the fine fibers in the papermaking pulp sludge and the condensed gypsum is weak, the swelling and shrinkage are likely to occur, and the fatal effect that the function as a building material is not exhibited. There were drawbacks.

An object of the present invention is to reuse papermaking pulp sludge as a means for reusing papermaking pulp sludge, which has higher strength than before, and has excellent dimensional stability, excellent nailing adhesion, high sound absorption, and low thermal conductivity. The purpose is to establish a method for producing pulp sludge gypsum board for strength building materials.

[0005]

As a result of examining the above proposed method, the reason that the strength of the pulp sludge gypsum board product is weak is that the force at the time of kneading is insufficient, and that the pulp sludge has the same fineness as the hydrated fine fibers. Due to insufficient contact with water gypsum and a large gap between the condensed gypsum and the pulp sludge, the bonding force between the fine fibers in the paper pulp sludge and the condensed gypsum is weak even during pressure molding, and swelling occurs. It has been found that shrinkage is likely to occur. The present inventor controlled the mixing state without adding any reinforcing material such as long fibers at all, and caused the water-containing fine fibers of the papermaking pulp sludge to approach the gypsum by generating instantaneous shearing force, The present inventors have found that it is possible to efficiently bond water containing fine fiber-containing water and gypsum, and to manufacture a gypsum board having excellent characteristics.

Based on this finding, the present invention relates to a method for producing a gypsum board for building materials by mixing papermaking pulp sludge and gypsum and press-molding the same. Mixing the Capillary (Capi) from the Fenicular-II region
llary) A method for producing a pulp sludge gypsum board for a high-strength building material, characterized in that the application of a shear force in a region is carried out so that the water adhering to the hydrous fine fibers and the gypsum are efficiently reacted. It is. Resins and / or reinforcing agents can also be added.

[0007]

[Function] By applying a shearing force from a fenicular II (Funicullav-II) region to a capillary (Capillary) region to a mixture of hydrated fine fibers of paper pulp sludge and hemihydrate gypsum, the hydrated fine fibers of pulp sludge are instantaneously added. The water content inside the gypsum is replaced by the saturated water of gypsum (the solution in which gypsum is dissolved and saturated, the same applies hereinafter). In addition, the mechanochemical reaction between the fine fibers of the papermaking pulp sludge and the hemihydrate gypsum particles causes the papermaking pulp to change. The dihydrate gypsum crystallization is completed from the fine fibers in the sludge, and the fine fibers in the papermaking pulp sludge and the condensed gypsum are completely adhered to each other.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Paper pulp sludge has a fineness of 20 to 150 μm.
Fiber of about μm and 0.5 to 10 μm used for papermaking
Aggregates such as clay (talc). In general, 4
It contains 0 to 60%, usually about 50% of attached water.
The solid composition is about 60% organic and about 40% inorganic, such as clay, calcium carbonate, alumina, magnesium, and titanium oxide. For reference, an example of the analysis is shown below (the sample is gray, granulated with a high molecular coagulant (1 to 10 ppm), fiber diameter: 100 to 200 μm, incinerated at 1000 ° C.): Na : 0.12% by weight, Ti: 0.59% by weight, Ca:
11.5% by weight, Cu: 0.02% by weight, Al: 12.
5 wt%, Fe: 0.54 wt%, Mg: 7.92 wt%, Mn: <0.01 wt%, Si: 15.1 wt%:
52.2% by weight of water.

Most of the adhering water is present in the organic fine fibers. Therefore, when mixing papermaking pulp sludge and gypsum, it is not possible to bring gypsum close to the water-containing fine fibers of pulp sludge by ordinary mixing. Further, even when the mixture thus formed is compression-molded and dried and solidified, the voids between the fine fibers and the condensed gypsum are large, and it is difficult to obtain a strong bonding force.

By the way, regarding the mixing operation of a solid and a liquid, a display method of classifying and displaying the degree of the filling state and the flowing state of the solid-liquid system in the following five stages has been already established academically. (See, for example, Kenji Hashimoto "Kneading Technology" Industrial Technology Center (1978)): Solid- liquid- gas phase state (1) Vendura area Continuous Discontinuous Continuous Basabasa (2) Phenylic area (I) Continuous Continuous Continuous Basabasa (3) ) Phenic region (II) Continuous Continuous Discontinuous Vasabasa (4) Capillary region Discontinuous Continuous Zero Sticky (5) Slurry region Discontinuous Continuous Zero Muddy

From the mixing operation method, each region is defined as follows: (A) Mixing (in a narrow sense): Bendular region (B) Kneading: Bendular region Phenylic region (I) Phenyl Culcular zone (II) (C) Kneading: phenicular zone (II) Capillary zone (D) Dispersion: Capillary zone Slurry zone

In the present invention, when mixing papermaking pulp sludge and gypsum, the mixing state of the water-containing fine fibers of the papermaking pulp sludge and gypsum is defined as a Funicular-II region as defined above. It is characterized in that it is controlled to apply a shearing force in a capillary region from the beginning. Due to the instantaneous shearing force generated, the adhesion moisture in the hydrated fine fibers of pulp sludge and the saturated water of gypsum are exchanged, and the mechanochemical between the fine fibers of paper pulp sludge and the hemihydrate gypsum particles. By the reaction, dihydrate gypsum crystallization is completed from the fine fibers in the paper pulp sludge, and the fine fibers in the paper pulp sludge and the condensed gypsum can be completely adhered, and pulp sludge gypsum for high-strength building materials High strength can be achieved in the board.

As the mixer that provides the above-mentioned mixing action, it is preferable to use a kneading machine having a kneading action, for example, a kneading machine of a tangential type or an overlap type. The kneading machine creates a kneading / kneading action by strong shearing force generated between two tough blades and between the blades and the kneading tank, and varies depending on the arrangement and shape of the blades. Is manufactured. In particular, the use of a tangential kneading machine is effective.
Examples of the blade shape include a sigma blade, a locator blade, a Z blade (simplex blade), and a double horn blade (fishtail blade). In any case, in the present invention, any kneading / kneading machine capable of generating a strong shearing action can be used. For example, as a batch type, a double arm type (Warner type) kneader, An internal mixer, a pony mixer, a muller and the like can be used, and as a continuous type, a conneader, a pug mill, a voeta type kneader and the like can be used.

Further, in the present invention, gypsum is preferably hemihydrate gypsum. However, even if dihydrate gypsum is used, it becomes high pressure and high temperature due to a mechanochemical reaction during special kneading, and gypsum is dehydrated. Since water gypsum is formed, it is the same as the case where hemihydrate gypsum is mixed, which is not a problem. The use of anhydrous gypsum is also possible.

Next, papermaking pulp sludge (water content 50%)
%) And hemihydrate gypsum are in a mixing ratio of 1.0: 0.5 to 1.0:
1.25 is preferred, and 1.0: 0.75 is preferred.
Even if there is too much gypsum in the papermaking pulp sludge gypsum board,
Conversely, if there is too much pulp sludge, the strength will decrease and the moldability will deteriorate.

Furthermore, considering the handling and moldability of paper pulp sludge gypsum board in production, natural resins and synthetic resins, including melamine resins, urea resins, vinyl acetate resins, and fibrous resins, are used in an amount of 0.1%. It is also effective to add about 5 to 5%. This is also effective in improving water resistance. In the present invention, sufficient strength can be obtained without adding a reinforcing material such as a long fiber at all. However, if further strength is desired, addition thereof is not hindered.

The pressure molding is carried out in a conventional manner by filling a kneaded material in a mold or other mold and applying an appropriate pressure of 5 to ²⁰ kg / cm ² . Thereafter, the papermaking pulp sludge gypsum board is manufactured by drying at room temperature or at an elevated temperature up to about 60 ° C.

The papermaking pulp sludge gypsum board of the present invention thus produced is used as a papermaking pulp sludge gypsum board as a substitute for a conventional gypsum board for building materials, in addition to the effective use of industrial waste from pulp and paper mills. It is more than three times as large as a commercial product, has a compressive strength as much as five times or more, has excellent nailing adhesion, and is expected to be used for wall materials, ceiling materials, roof base materials and the like.

Examples and Comparative Examples 900 parts of paper pulp sludge (water content 52%, solid content 48%, of which 55% organic and 45% inorganic) and 675 parts of calcined gypsum (semihydrate gypsum) were used in a tanden kneader. (3 liter capacity: Inoue Seisakusho), kneading and kneading were performed for 15 minutes, the kneaded material was put in a mold, and pressure-molded at a pressure of 10 kg / cm ² . This was taken out and dried at 45 ° C. for 24 hours. 12m thick
/ M, 300 m / m × 300 m / m compression molded plate was obtained. Its bulk specific gravity, flexural strength and compressive strength characteristics are shown below in comparison with commercial products. The bending test is based on JIS A140
According to No. 8, the test specimen was supported on a jig at two places near both ends, the maximum strength up to breaking was measured, and the bending strength was calculated according to a known equation. In the test, the specimen was left at room temperature for 3 hours after preparation and left for 24 hours in a dryer at 45 ° C.
Performed after standing for days. The compressive strength was also calculated by dividing the maximum strength to failure after the same condition by the cross-sectional area:

Significantly improved strength was obtained over the commercial product. In addition, the dimensional stability was excellent and the nailing adhesion ability was also excellent. Sound absorption and thermal conductivity were also sufficient for building material applications.

[0021]

According to the present invention, it is possible to produce a high-strength paper pulp sludge gypsum board as a substitute for a gypsum board for building materials, in addition to the effective use of industrial waste from a pulp and paper mill. Compared with the conventional product, the bending strength of the paper pulp sludge gypsum board of the present invention is more than 3 times and the compressive strength is more than 5 times, and it also has excellent nailing adhesion ability, excellent dimensional stability, and high sound absorption. Because of its low thermal conductivity, it can be used for various building materials such as wall materials, ceiling materials, and roof base materials.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C04B 18/24 C04B 28/02-28/08 B28C 5/12

Claims (2)

(57) [Claims] 1. A method for producing a gypsum board for a building material by mixing papermaking pulp sludge and gypsum and press-molding the mixture, wherein the mixing of the water-containing fine fibers of the papermaking pulp sludge with gypsum is carried out by using Funicular-II. II) A pulp sludge gypsum board for a high-strength building material characterized by efficiently reacting the adhering water of hydrous fine fibers with gypsum by applying a shearing force from the area to the capillary (Capillary) area. Production method. 2. The method for producing pulp sludge gypsum board for high-strength building materials according to claim 1, further comprising a resin and / or a reinforcing agent.