JP2003292366A - Gypsum-based inorganic set object and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gypsum-based inorganic set object and a method for producing the same. <P>SOLUTION: The gypsum-based inorganic set object being an inorganic set object containing gypsum and an organic reinforcing fiber and containing 10-50% mass molten slag powder having a basicity of 1.50 or lower, a fineness of 2,000-5,000 cm<SP>2</SP>/g, and 90 ×m oversize fraction of 5% mass or smaller and the method for producing the same are provided. The gypsum-based inorganic set object containing the molten slag has excellent strength, a low dimensional change upon absorption of moisture, is excellent in incombustibility and fire resistance, and is useful as an interior material for a building material. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a gypsum-based inorganic hardened material containing a molten slag obtained from waste.

[0002]

2. Description of the Related Art Gypsum-based cured products such as fiber gypsum boards and gypsum tiles are widely used as building materials for interiors such as walls and ceilings because of their excellent workability and low cost.
Such a gypsum-based cured product is generally manufactured by mixing paper with a reinforcing fiber, a filler, and the like, and by papermaking molding or extrusion molding. In recent years, pulp has been mainly used as a reinforcing fiber due to the demand for non-asbestos, and fillers such as calcium carbonate powder and granulated steel slag have been added for the purpose of strengthening the strength.

However, when pulp is used, the obtained cured product has problems such as a large dimensional change due to water absorption and a low fire resistance, which makes it impossible to obtain properties as a noncombustible material. On the other hand, when calcium carbonate is added, decarboxylation decomposition occurs at around 650 ° C, which causes harmful deformation such as cracks and explosions on heating, and importance is placed on nonflammability and fire resistance. However, when the steel granulated slag is mixed, the basicity of the slag is substantially 1.80.
Or, since it is more than that, there is a potential for hydraulic reactivity, forming an ettringite hydration product, resulting in a large dimensional change, and problems such as not being able to obtain properties as a noncombustible material. It was

[0004]

DISCLOSURE OF THE INVENTION The present invention provides a gypsum-based material which has a small dimensional change even when pulp is used, is free from cracks after construction, and is thermally inactive (nonflammable, fireproof). It is intended to provide an inorganic cured body.

[0005]

Means for Solving the Problems The inventors of the present invention have made earnest studies in view of such circumstances, and as a result, by blending a specific amount of a specific molten slag powder, the dimensional change rate is low, and the incombustibility and fire resistance are low. The present invention has been completed by finding that a gypsum-based inorganic hardened material having excellent properties can be obtained.

That is, the present invention relates to an inorganic hardened material containing gypsum and organic reinforcing fibers, a molten slag having a basicity of 1.50 or less, a fineness of 2000 to 5000 cm ² / g, and a 90 μm residue of 5% by mass or less. The present invention provides a gypsum-based inorganic hardened material obtained by mixing 10 to 50 mass% of powder, and a method for producing the same.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The molten slag used in the present invention is obtained by melting general waste or waste such as sewage sludge alone or in combination of two or more kinds at 1200 ° C. or higher, and after being melted, granulated in water. It is preferable to use one. It can decompose dioxins and detoxify them by melting at over 1200 ° C, and gasify heavy metals such as low boiling point mercury, lead, cadmium and zinc, and reduce the content to below the national standard value. .

The components of such molten slag vary depending on the type of waste and are not particularly limited, but approximately 20 to 40% by mass of CaO, 10 to 20% by mass of Al ₂ O _{3 and} 10 to 20% by mass of MgO are contained. 1 to 8 mass%, and SiO ₂ is 30 to 50 mass%.

The basicity of the molten slag is (CaO + Al ₂
The value expressed by (O ₃ + MgO) / SiO ₂ is 1.50 or less. When it exceeds 1.50, the reactivity of gypsum and slag increases, and it becomes impossible to obtain the reduction ratio of dimensional change and nonflammability. The lower limit of basicity is not particularly limited, but is 1.00
The above is preferable.

The fineness of the molten slag powder is 2000-5.
It is necessary that the 90 μm residue at 000 cm ² / g be 5 mass% or less. If it is less than this range, the strength of the cured product will be low and the surface will be roughened, making it difficult to obtain good surface properties as a building material. On the other hand, if it is too fine, the strength decreases and the dimensional change rate due to water absorption increases, and the elution of a trace amount of heavy metals contained therein also increases.

The blending amount of the molten slag powder is 1 of the total blending amount.
It is set to 0 to 50% by mass. By having such a blending amount, it has excellent strength, small dimensional change due to water absorption,
Further, a cured product having properties as an incombustible material can be obtained. If the blending amount of the molten slag powder is 10% by mass or less, the problems of reduction of dimensional change rate and improvement of noncombustible material properties cannot be solved, and if it is 50% by mass or more, sufficient strength as a product cannot be obtained.

Such molten slag powder is an inactive powder and acts as an aggregate due to its lack of hydration reactivity with gypsum containing alkali components, and a hardened product containing this is shown in the examples described later. As described above, there is an effect of reducing the rate of change in length. Further, since it is once heated and melted and is also thermally inactive, it is possible to exhibit excellent characteristics of noncombustibility.

As the gypsum in the inorganic hardened body of the present invention,
Hemihydrate gypsum and anhydrous gypsum can be mentioned, and these may be natural gypsum or chemical gypsum. Chemical gypsum is eliminated
It is a by-product during the production of phosphoric acid, hydrofluoric acid, etc.
Since it is strongly acidic, it has a pH of 7.0 or higher, preferably 9.0 to 12 with an alkaline material such as slaked lime in order to suppress the rust of each part during manufacturing and the rust of nails during construction. Adjust to .5. In this case, the addition amount of the alkaline material is 0.5 to
It is about 3.0% by mass. If the amount is larger than this amount, the hydration of gypsum is inhibited, which is not preferable. Such gypsum is 40-
80% by mass, preferably 45 to 75% by mass, is blended, and the fineness thereof is 3000 to 8000 cm ² / g.
A degree is preferable.

Examples of the organic reinforcing fibers in the inorganic cured product of the present invention include pulp, vinylon, polypropylene, rayon, various hemps, and the like, and two or more kinds of them can be used in combination. Of these, organic fibers mainly composed of pulp are preferred from the viewpoint of noncombustibility. The freeness of pulp is Canadian Standard Freeness.
(csf) is 150 to 600 mL. In addition to such organic reinforcing fibers, general-purpose inorganic fibers such as glass fibers and alkali resistant glass fibers may be used in combination.

The content of the organic reinforcing fibers is 3 to 15% by mass, preferably 4 to 10% by mass.

If desired, the inorganic hardened material of the present invention may be blended with other admixtures used in ordinary gypsum-based hardened materials such as fillers. Examples of the filler include limestone, various slags, silica stones, fly ash, wollastonite, mica, talc, sepiolite, diatomaceous earth, silica fume, kaolin, zeolites, clays, gypsum dihydrate,
General-purpose mineral powders such as anhydrous gypsum and product scrap can be used. Such fillers can be used in combination of several kinds, if necessary, and are preferably blended in an amount of 10 to 30% by mass.

The gypsum-based inorganic hardened body of the present invention can be produced by adding water to a mixture containing gypsum, organic reinforcing fibers and molten slag powder, kneading, paper-making or extrusion-molding, and then curing. For example, in the case of paper forming, gypsum, molten slag and organic reinforcing fiber are mixed, and water is added to these raw material blends to knead to form a slurry (slurry temperature is 25 ° C or higher, particularly 28 to 40 ° C). Is preferable), by adding a flocculant to this slurry if necessary,
Paper is made by a general-purpose paper making machine such as a round-net paper making machine, a Fourdrinier paper making machine, or a flow-on machine, and if necessary, a thin film is wound up using a making roll.
About 20 mm) is manufactured. Next, the formed green sheet is subjected to surface pressing at a holding pressure in the range of 10 to 30 N / mm ² to be molded.

In the case of extrusion molding, a small amount of water is added to the raw material mixture to prepare a kneaded product, and the kneaded product is put into an extrusion molding machine to form a uniform shape through the die. A general-purpose extruder is used, but it is necessary to have a vacuum degassing mechanism. By extrusion molding, thin to thick products, solid to hollow products having complex shapes can be manufactured. Curing is performed on the obtained molded body, but normal pressure curing is preferable, and it is particularly preferable to perform normal pressure curing in the range of low temperature to room temperature for about 1 day to 1 week.

[0019]

EXAMPLES The present invention will be described in more detail below with reference to examples. The raw materials and test methods used in Examples and Comparative Examples are as follows. <Raw materials> 1. Anhydrous gypsum: Anhydrous gypsum hydrofluoric acid, fineness 2800 cm ² / g 2. Molten slag: slag powder that is obtained by melting waste at 1250 ° C, quenching water granulation, and crushing, basicity = 1.15, CaO = 28.8, Al ₂ O ₃ = 15.7, MgO = 4.1, SiO ₂ = 42.
4% by mass, basicity = 1.44, CaO = 34.3, Al ₂ O ₃ = 15.7, MgO = 4.6, SiO ₂ = 37.
8 mass%, basicity = 1.72, CaO = 38.0, Al ₂ O ₃ = 16.2, MgO = 4.9, SiO ₂ = 34.
3% by mass, basicity = 1.93, CaO = 42.5, Al ₂ O ₃ = 14.7, MgO = 6.2, SiO ₂ = 32.
8% by mass (granulated iron and steel slag: granulated slag by-product of steel production, manufactured by Daiichi Cement Co., Ltd., fineness: 3480 cm ² / g) 3. Calcium carbonate powder: Okutama Industry Co., Ltd., fineness
3500 cm ² / g 4. Bleached pulp: New Zealand pulp, freeness (Canadian Standard Freeness: csf) 270mL

<Test method> 1. Fineness: Measured according to the fineness test of JIS R5201 2. Bulk density: measured by ^{JIS A5430 (g / cm 3)} 3. Bending strength: Measured according to JIS A5430 (N / mm ² ) 4. Dimensional change rate: Measured by JIS A5430 (%) 5. Thermal expansion / contraction rate: In accordance with the Ministry of Construction Notification No. 2999 fire resistance performance test method, the expansion / contraction rate (shrinkage rate) was measured after heating to 1010 ° C. for 2 hours according to the fire resistance curve, and after cooling. Surface test: According to the former Ministry of Construction notification No. 1828 surface test of non-combustible material, in the surface test, from during heating to after test 3
Evaluation of occurrence of cracks up to 0 seconds: No cracks: ○, slight cracks: △, several cracks exceeding the plate thickness: ×

Examples 1 to 4 and Comparative Examples 1 to 7 Using the raw materials shown in Tables 1 and 2, papermaking was carried out by an ordinary cylinder net making machine, 4 layers were wound up on a making roll, and a thickness of 6 was obtained.
A green sheet having a size of 910 mm × 1820 mm was obtained. The green sheet was surface-pressed at 20 N / mm ^{2 and} cured at about 20 ° C. for about 1 week in a moist air atmosphere, then dried and tested. The results are also shown in Tables 1 and 2.

[0022]

[Table 1]

[0023]

[Table 2]

Examples 5 to 8 and Comparative Examples 8 to 14 Using the raw materials shown in Tables 3 to 4, the materials were molded by an extruder having a vacuum degassing mechanism through a die of 10 × 200 mm. The molded body was aged at about 20 ° C. for about 1 week in a moist air atmosphere, then dried and tested. The results are also shown in Tables 3 and 4.

[0025]

[Table 3]

[0026]

[Table 4]

From the above, it was shown that the cured product of the present invention has a smaller dimensional change due to water absorption and a smaller expansion / contraction rate with respect to heat than the comparative product.

[0028]

The gypsum-based inorganic hardened material containing the molten slag of the present invention has excellent strength, low dimensional change rate due to water absorption, and excellent incombustibility and fire resistance, and is used as an interior material for building materials. It is useful.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Miu Hato             2-12-10 Shiba Daimon, Minato-ku, Tokyo Stock market             Company A & A Material (72) Inventor Minoru Harada             Kashima-ken, 1-2-7 Moto-Akasaka, Minato-ku, Tokyo             Inside the corporation (72) Inventor Shinsaku Maruyama             11-1 Haneda Asahi-cho, Ota-ku, Tokyo Co., Ltd.             Inside the EBARA CORPORATION F-term (reference) 4G012 PA22 PA24 PA25 PE04                 4G052 GA04 GA11 GA25                 4G054 AA02 AA15 AA20 BD00

Claims (2)

[Claims] 1. An inorganic hardened body containing gypsum and organic reinforcing fibers, having a basicity of 1.50 or less and a fineness of 2000.
A gypsum-based inorganic hardened body obtained by blending 10 to 50% by mass of molten slag powder having a 90 μm residue of 5% by mass or less at 5,000 cm ² / g. 2. The gypsum-based inorganic hardening according to claim 1, wherein water is added to a mixture containing gypsum, organic reinforcing fibers and molten slag powder, and the mixture is kneaded, paper-formed or extrusion-molded, and then cured. Body manufacturing method.