JPH09183647A - Paper pulp sludge gypsum board and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a paper pulp sludge gypsum board with high strength useful for building materials as a reutilizing means of paper pulp sludge and its production method. SOLUTION: In the gypsum board using the paper pulp sludge as a reinforcing agent, the affinity between normally added hemihydrate gypsum added later and fine fibers of the pulp sludge is enhanced by preliminarily impregnating a trace amount of hemihydrate gypsium into the water stuck to the fine fibers of the paper pulp sludge, thus both is capable of being approached most closely, and the paper pulp sludge gypsum board is obtained as a strong combined body. Beside, by adding a mildewproofing chemical together with the normally added hymihydrate, a mildewproofing paper pulp sludge gypsum board holding a mildewproofing effect is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a papermaking pulp sludge gypsum board for a highly reinforced building material obtained by reusing papermaking pulp sludge and a manufacturing method.

[0002]

2. Description of the Related Art Papermaking pulp sludge is currently incinerated in large quantities as industrial waste or is disposed of by landfill. On the other hand, as a method of reusing it, it has been proposed to recycle it as a plaster board for building materials. As a method for producing a gypsum board using papermaking pulp sludge, a synthetic fiber or a long fiber such as glass wool is added as a reinforcing material to a papermaking pulp sludge, mixed with gypsum, and a method for producing a gypsum board for building material which is pressure-molded. Has been proposed (Japanese Patent Laid-Open No. 50-9).
5322). In addition, as a method for producing a high-strength building material gypsum board using papermaking pulp sludge, after adding sulfuric acid to the pulp sludge slurry at a papermaking factory, this was neutralized with slaked lime, and slaked lime neutralized pulp A method for producing gypsum board using sludge as a raw material has been proposed (Japanese Patent Laid-Open No. 5-301462).

[0003]

Among them, the method disclosed in Japanese Patent Laid-Open No. 50-95322 is such that long fiber is added as a reinforcing agent to papermaking pulp sludge, whereby the added fiber and gypsum are entangled. The basic idea is to improve the strength at the time of molding by giving the property. However, the gypsum board obtained by this proposed method, when kneading, the contact between the water-containing fine fibers of the papermaking pulp sludge and the hemihydrate gypsum is insufficient, and since the gap between the condensed gypsum and the pulp sludge is large, Even during pressure molding, there was a fatal defect that the binding force between the fine fibers in the papermaking pulp sludge and the condensate gypsum was weak and expansion was apt to occur, and a sufficient function as a building material could not be exhibited.

Further, in the method of Japanese Patent Laid-Open No. 5-310462, sulfuric acid is added to the pulp sludge slurry after neutralizing slaked lime so that a small amount of gypsum is preliminarily generated in the water-containing fiber of the papermaking pulp sludge. The method called processing is adopted. The fact that gypsum is generated in advance in the papermaking pulp sludge has the function of improving the compatibility between the pulp sludge and gypsum when the gypsum is added and kneaded later. However, the biggest drawback of this proposal is that (1) sulfuric acid is added to the pulp sludge discharged from the paper mill, and (2) it is then neutralized with slaked lime to form fine fibers in the pulp sludge. By producing gypsum and then producing lime-neutralized pulp sludge, the amount of this sludge is doubled, and (3) the wastewater accompanying the slaked lime neutralization treatment becomes a saturated solution of calcium sulfate and contains gypsum. Although pulp sludge can be obtained, there is a problem that the waste liquid generated by the lime neutralization treatment needs to be treated again.

Further, the fine fibers in the papermaking pulp sludge are a nutrient source for molds and fungi, and when the papermaking pulp sludge is converted into gypsum board, various molds are generated on the surface of the board depending on the degree of humidity in the room. In some cases.

[0006]

Means for Solving the Problems As a means for reusing papermaking pulp sludge, the present inventor has proposed a gypsum board for building materials having a higher strength than conventional gypsum boards, while maintaining antifungal performance. As a subject of the present invention, earnest studies have been made to establish a method for producing a mildew-proof paper pulp sludge gypsum board excellent in stability and nail retention. Therefore, the present inventor has added sulfuric acid to the pulp sludge slurry to neutralize slaked lime, without producing gypsum by the reaction, and directly in the spot in the adhering water of the fine fibers in the papermaking pulp sludge, in advance. By impregnating the hemihydrate gypsum of the above, the added hemihydrate gypsum and the fine pulp fibers are well compatible with each other, and it is possible to bring both of them closer to each other, so that the fine hydrous fibers and the hemihydrate gypsum are efficiently combined. It has been found that it is possible to manufacture a gypsum board having high strength and excellent characteristics by a mass production method that does not use a special kneading device.

In the present invention, when a small amount of hemihydrate gypsum is added to the papermaking pulp sludge in advance, the added hemihydrate gypsum dissolves in the adhering water in the fine fibers of the papermaking pulp sludge to form hemihydrate gypsum CaSO ₄ .. Saturated solubility of 1 / 2H ₂ O (CaSO ₄ · 1 / 2H ₂ O 6 to 10 g / l · 2
In a trace amount of solution that reached 5 ° C, dihydrate gypsum Ca was gradually added.
Precipitating SO ₄ · 2H ₂ O, in the pulp the fine fibers,
It produces a small amount of gypsum dihydrate. Thus, having dihydrate gypsum in the fine fibers has an extremely important effect of improving the compatibility between the hemihydrate gypsum to be subsequently added and the pulp fine fibers. If the amount of the hemihydrate gypsum added in advance is too large, the amount of water adhering to the papermaking pulp sludge will be insufficient, and the compatibility with the pulp sludge fine fibers will deteriorate.

The inventors of the present invention, when adding gypsum to a papermaking pulp sludge that has been impregnated with a small amount of hemihydrate gypsum in advance and kneading it, add an antifungal agent to the papermaking pulp sludge at 0.1%.
% To 5%, it was found that the antifungal effect can be exhibited without deteriorating the original strength performance of the papermaking pulp sludge gypsum board, leading to the completion of the antifungal papermaking pulp sludge gypsum board and the manufacturing method. It was
Here, hemihydrate gypsum is CaSO ₄ 1 / 2H such as calcined lime
Means ₂ O, and the condensate gypsum, dihydrate gypsum CaSO ₄ · 2
It means H ₂ O.

In the present invention, the gypsum is preferably hemihydrate gypsum, but when impregnating a small amount of hemihydrate gypsum in advance in the adhered water of fine fibers in papermaking pulp sludge, dihydrate gypsum may be used.

[0010]

EXAMPLES Papermaking pulp sludge is an aggregate of fibrous material of about 20 to 800 μm and talc of about 5 to 50 μm. Generally, it contains 40 to 60%, usually about 50% of attached water. Solid content composition is 45% organic, inorganic,
It is composed of about 55% of tarley, calcium carbonate, alumina, magnesia, titanium oxide and the like. For reference, the analysis value of one example is shown below. (Sample is brown, granulated with polymer coagulant, fiber length 100-1500 μm, 8
Ash at 50 ° C.) Ca: 2.46%, Al: 21.9%, Mg: 4.59
%, Ti: 0.80%, Si: 17.6%, S: 0.2
1%, K: 0.40%, Fe: 1.86%, Mn: 0.
03%, Cu <0.01%, Zn: 0.05%, residual quantity of ignition (850 ° C): 29.7%

When the papermaking pulp sludge (50% of water adhered) is impregnated with a slight amount of hemihydrate gypsum in advance, the addition amount is from 1 to
It is 10%, preferably 3 to 5%. If the amount of hemihydrate gypsum added is too large, the adhered water in the papermaking pulp sludge will be insufficient and the compatibility between the fine fibers and gypsum will be poor. If it is too small, the fine fiber and plaster will not be compatible with each other.

Next, the mixing ratio of gypsum-impregnated papermaking pulp sludge and hemihydrate gypsum is 1.0: 0.5 to 1.0: 1.
25 is preferable and 1.0: 0.75 is preferable. If the amount of gypsum in the papermaking pulp sludge gypsum board is too large, or conversely, if the amount of papermaking pulp sludge is too large, the strength of the solidified product is lowered and the formability is poor.

The antifungal agent added to the papermaking pulp sludge is preferably a water-soluble phenolic resin or an alcohol-soluble phenolic resin in consideration of handling in manufacturing, moldability, etc., but a commercially available antifungal agent such as chloroxylenol may also be used. It doesn't matter. Paper pulp pulp sludge (50% water adhesion)
On the other hand, it is 0.1 to 5%, preferably 0.5 to 3%. If it is too large, the strength of the mildew-proof paper pulp sludge gypsum board is reduced.

Papermaking pulp sludge [water content 55%, solid content 45%, (of which organic matter 45%, inorganic matter 55%)] 100
50 parts of hemihydrate gypsum (calculated gypsum) was added to 0 parts, and a small mixer for concrete (capacity 30 l, 25 rpm, 50 mm
Kneading is carried out for 10 minutes using φ alumina balls to prepare a slight amount of hemihydrate gypsum impregnated paper pulp sludge.

Then, to 1050 parts of the gypsum-impregnated paper pulp sludge mother material, 700 parts of hemihydrate gypsum and 50 parts of alcohol-based phenol resin, phenol, formaldehyde-based, Aikaneoresin P-75 (nonvolatile content 59%) are added. After that, the above small mixer for concrete is kneaded for 15 minutes, the kneaded product is put into a mold, and the pressure is 10 kg / cm.
^It was pressure molded at ² . This was taken out and dried at 60 ° C. for 12 hours. A compression-molded plate having a thickness of 12 m / m and 300 × 300 m / m was obtained. The results of the bulk specific gravity, bending strength and compressive strength characteristics are shown below. The bending test was performed according to JIS A1408, and the compression strength test was performed according to JIS R5201. The bulk specific gravity was 1.20 g / cm ³ , the bending strength was 70 kg / cm ² , and the compression strength was 230 kg / cm ² . The test results of the commercial gypsum board are shown as comparative examples. Bulk specific gravity 0.75 g / c
m ³ , bending strength 19 kg / cm ² , compressive strength 39 kg /
cm ² .

The compression-molded plate obtained above was used for 25-30'C,
When a mold prevention test was conducted at a humidity of 85%, no mold formation was confirmed even after 6 months. On the other hand, as a comparative test plate, a comparative sample which was not mixed with a mildew proofing agent was subjected to a mildew proofing test under the same conditions.

[0017]

INDUSTRIAL APPLICABILITY The present invention provides a papermaking pulp sludge gypsum board as a novel gypsum board for building materials by effectively utilizing industrial waste from a papermaking factory.

The papermaking pulp sludge gypsum board of the present invention has a bending strength and a compressive strength which are 3 to 5 times higher than conventional gypsum boards, excellent nail retention performance, and high dimensional stability.
Since it has a high sound absorbing property, it can be used for various building materials such as wall materials and ceiling materials.

Further, the papermaking pulp sludge gypsum board having the antifungal effect can be used regardless of the place of use because it is not affected by humidity and the like.

The production method of the present invention can improve the compatibility between the papermaking pulp sludge and gypsum without any special treatment.

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display area C04B 18:24 24:30) 103: 69 111: 20

Claims (3)

[Claims] 1. A gypsum board using papermaking pulp sludge as a reinforcing material, wherein a small amount of gypsum is impregnated in the papermaking pulp sludge, and the gypsum-impregnated papermaking pulp sludge is mixed and molded and solidified. A papermaking pulp sludge gypsum board characterized by being made. 2. Using papermaking pulp sludge as a reinforcing material,
When mixed with gypsum and molded and solidified, a first step of impregnating a small amount of gypsum in advance in the papermaking pulp sludge, a second step of mixing gypsum with the gypsum-impregnated papermaking pulp sludge, and a third step of molding and solidifying A method for producing a papermaking pulp sludge gypsum board, which comprises the steps of: 3. The method for producing a papermaking pulp sludge gypsum board according to claim 2, wherein a fungicide is mixed in the second step.