JPH05246742A - Cement composition for extrusion molding - Google Patents

Abstract

PURPOSE:To provide the subject composition capable of producing cement- molded body having excellent moldability with low extrusion pressure in extrusion molding, and excellent surface smoothness, bending strength and workability such as nailing property in low-density products even without using harmful asbestos. CONSTITUTION:This cement compsn. for extrusion molding contains 1-30 pts.wt. brucite and 1-40 pts.wt. pulp to 100 pts.wt. of cement.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an extrusion molding cement composition.

[0002]

2. Description of the Related Art Conventionally, molded products obtained by extrusion-molding a cement composition onto walls, floors, roofs, etc. and curing it have been used. In order to extrude a cement composition, the following properties are required for the cement composition. High fluidity in the clay state with added water and low extrusion resistance (extrudability). High shape retention that keeps the composition connected to each other even after being extruded. The composition is completely dispersed and the surface of the molded product is smooth
(Surface smoothness). Excellent reinforcement effect to increase the strength of the molded product after curing. Asbestos has been conventionally used to satisfy the above required performance. However, it has become clear in recent years that asbestos has carcinogenicity, and it has become clear that there is a risk that the health of the asbestos-containing cement molded product may be significantly impaired by inhaling dust of the asbestos during the production and use thereof.

From such a background, molded articles which do not use asbestos are currently required. As such, there have been proposed one using a specific pulp as the reinforcing fiber (Japanese Patent Laid-Open No. 63-256555) and one mixed with sepiolite (Japanese Patent Laid-Open No. 63-123851). All of these are applied to the production of lightweight cement compacts, when the cross-sectional area of the molded product is small relative to the screw diameter of the extruder, or the cross-sectional shape of the molded product is complicated and the ratio of the cross-sectional peripheral length to the cross-sectional area is large. In such a case (when the extrusion pressure tends to rise, such as when molding a thin plate), there are problems that molding becomes difficult, strength decreases, and surface irregularities occur (poor surface smoothness of the molded body). there were. In addition, there has been a problem that when an attempt is made to increase the extrusion speed in order to improve productivity, the molding pressure becomes abnormally high and high-speed extrusion molding cannot be performed.

[0004]

DISCLOSURE OF THE INVENTION The present invention provides a product which has a low extrusion pressure during extrusion molding and is excellent in moldability without using harmful asbestos, and has surface smoothness, bending strength and low density. Another object of the present invention is to provide a cement composition for extrusion molding capable of producing a cement molded product having excellent workability such as nailing.

[0005]

Specifically, the present invention relates to a cement composition for extrusion molding containing 1 to 30 parts by weight of brucite and 1 to 40 parts by weight of pulp with respect to 100 parts by weight of cement.

In the present invention, as the cement, blast furnace cement, Portland cement alumina cement,
Any of silica cement, fly ash cement, sulfate cement and the like can be used, and brucite and pulp are mixed with this to prepare a cement composition for extrusion molding.

Brucite is also called bluesstone or hydrotalcite, and is a natural hydroxide of magnesium represented by the chemical formula Mg (OH) _2, which is vein-shaped as a low-temperature hydrothermal mineral in serpentine or chlorite schist. To produce. The shape is plate-like, leaf-like, or fibrous, but fibrous is preferable for the present invention. Color white, pale green, gray, a light blue, host rock M _g ²⁺ ions in the crystal often is often a part of which is substituted in Fe ^2+, Mn ^2+, also in the fiber In some cases, the chemical composition often contains various metals in addition to Mg. An example is shown below. MgO 62.2% FeO 6.5% SiO ₂ 1.6% Al ₂ O ₃ 0.3% MnO 0.3% CaO 0.2% H ₂ O 28.9%

Fibrous brucite used in the present invention
(Hereinafter, abbreviated as brucite) has a fiber diameter of 0.05 to
5μ, fiber length is 5μ ～ several hundred mm depending on the difference of crystal growth process
It has a wide range of fiber diameters, but the fiber diameter is 0.1-2.
μ, and fiber length of 10 μ to 20 mm are preferable.

The blending amount of brucite is 100 parts of cement.
It is 1 to 30 parts by weight, preferably 2 to 25 parts by weight, relative to parts by weight. If the blending amount of brucite is less than 1 part by weight, the effect of improving the extrudability by blending brucite will not be sufficiently obtained, and if it is more than 30 parts by weight, the fluidity of the cement composition will be deteriorated and complicated. Moldability deteriorates, for example, it becomes difficult to mold a large molded product.

The type of pulp used in the present invention is not particularly limited, but virgin pulp is preferred to waste paper pulp. The fiber length of pulp is 0.05 to 5 mm, preferably 0.1 to 3 mm. The amount of pulp added is 1 to 40 parts by weight, preferably 2 to 30 parts by weight, based on 100 parts by weight of cement. When the fiber length is short or the amount of addition is small, there is no synergistic effect with brucite to improve the moldability, and there is no reinforcing effect that is generally used for pulp. On the other hand, if it is too long or too much, the dispersion becomes poor, and the surface smoothness of the molded product deteriorates.

The brucite / pulp weight ratio is 0.1.
-10, preferably 0.2-5 is preferable. If this ratio is large, the moldability will be poor, and conversely if it is small, the moldability will be poor and the dispersibility will also be poor. If desired, the fiber-reinforced cement composition according to the present invention may further contain fine particles and / or perlite having a porous closed cell structure.

The fine particles used in the present invention include inorganic fine particles such as magnesium hydroxide powder, calcium silicate powder, mica, calcium carbonate, magnesium carbonate, talc, fly ash and silica fame, and burned chaff powder. Organic fine particles are exemplified, and these can be used alone or in combination. The particle size of the fine particles is 0.1 to 500 μm, preferably 3 to 4
It is 00 μm. The mixing amount of fine particles is 100
0.5 to 30 parts by weight, preferably 1 to 2 parts by weight
0 parts by weight. If all of these values are out of the above range, the moldability is poor, and if the particle size is large or the addition amount is large, the strength is also lowered.

The perlite used in the present invention is
It is a perlite obtained by firing and foaming pearlite or obsidian, and has a closed-cell porous foam structure in which minute closed cells are aggregated. Hitherto, perlite with a hollow structure made by firing and foaming obsidian or pearlite has been used as a lightweight aggregate, but since these are single-cell structures such as ping-pong balls, they are easily and easily destroyed during kneading. And the weight saving effect is completely lost. Compared to this,
The porous pearlite of the present invention has high strength due to its independent porous foam structure, and thus is less likely to be broken during kneading,
Also, even if it is destroyed, the debris will not lose its weight-reducing effect because there are bubbles in it, and the debris will not have a flat shape like conventional pearlite, but will maintain the particle shape because of its independent bubbles. Prevents deterioration of extrusion moldability.

The average particle size of the porous pearlite is 0.2 to
It is 1.2 mm, preferably 0.3 to 1.1 mm. If the particle size is less than 0.2 mm, the extrusion pressure during extrusion will increase and the formability will deteriorate, and if it is greater than 1.2 mm, the extrusion pressure during extrusion will increase and the formability will deteriorate as well. Not only that, but also when weight reduction is required, the weight reduction efficiency decreases.

The porous pearlite has a particle size of 0.15 to 1.
The distribution ratio of 3 mm is 70% or more, preferably 80%
The use of the above-mentioned materials is preferable because the moldability and workability are further improved.

The bulk density of porous pearlite is 0.15.
To 0.3 g / cm ³ , preferably 0.17 to 0.25 g / cm ^3.
Is. If the density is less than 0.15 g / cm ³ , the porous pearlite is likely to be broken, the efficiency of weight reduction is lowered and the formability is deteriorated, and if it is more than 0.3 g / cm ³ , weight reduction is achieved. Not only can it not be done, but the moldability also deteriorates.

The amount of porous pearlite is usually 1 to 120 parts by weight, preferably 3 to 100 parts by weight, based on 100 parts by weight of cement. The amount of pearlite added depends on the density of the molded body. In order to reduce the weight, it is necessary to add 30 parts by weight or more. If the amount used is less than 1 part by weight, there is no effect of improving the moldability, and if it is too large, the moldability deteriorates.

The above-mentioned cement composition for extrusion molding of the present invention containing cement, brucite, perlite and optionally fine particles and / or perlite is first thoroughly mixed in a dry state, and an appropriate amount of water is added thereto. A kneaded mixture is kneaded, the resulting kneaded product is extrusion-molded under pressure, and the obtained molded product is left (cured) under predetermined conditions to be dried and solidified to obtain a cement molded product.

General equipment may be used for the above-mentioned mixing step, kneading step and extrusion molding step.

The amount of water used is not particularly limited as it varies depending on the blending amount of each of the above components and extrusion molding conditions, but it is generally 25 to 100 parts by weight of cement.
It is 250 parts by weight, preferably 30 to 200 parts by weight.

The cement composition of the present invention may optionally contain additives such as reinforcing fibers, plasticizers and aggregates in addition to the above-mentioned components, if necessary.

Examples of the reinforcing fiber include organic fiber such as vinylon, polypropylene (PP), polyethylene, acrylic resin, aramid, polyester and carbon, metal fiber such as stainless fiber, and inorganic fiber such as rock wool. These are effective in improving the shape retention of the uncured cement molded body after extrusion molding, and the bending strength and impact resistance of the obtained cement molded body, but are required in the manufacturing process such as whether autoclave curing is performed or not. Its heat resistance limits its use.

Examples of the plasticizer include methyl cellulose and hydroxyethyl cellulose. The plasticizer includes
When each component of the composition is mixed and extrusion-molded, it has a function of imparting viscosity to the kneaded product and improving moldability, and the amount used is 0.5 to 10 parts by weight with respect to 100 parts by weight of cement. is there. If the amount used is small or large, the viscosity of the kneaded product becomes unsuitable, resulting in poor moldability.

When the above-mentioned reinforcing fiber is added, the amount of the organic fiber is 0.5 to 1 with respect to 100 parts by weight of cement.
0 parts by weight, 2 to 20 parts by weight in the case of metal fibers,
In the case of inorganic fibers, the amount is 1 to 20 parts by weight, and if the amount added is small, there is no reinforcing effect, and if the amount is large, the dispersibility is poor and the surface smoothness of the molded article is reduced.

Examples of aggregates include sand, crushed sand, blast furnace slag, silica sand, and silica stone powder. These can be used alone or in combination, but when autoclave curing is carried out, silica sand containing a large amount of SiO ₂ and synthesizing calcium silicate to contribute to improvement in strength and dimensional stability of the molded product , Silica stone powder is preferred. The particle size of the aggregate is 0.01 to 2 mm. If the particle size is smaller than the above range, the formability is poor, and if it is larger than the range, the workability is deteriorated. The amount of aggregate used is
It is 50 to 150 parts by weight with respect to 100 parts by weight of cement. If the amount used is less than the above range, there will be no reinforcing effect, and if it is more than the above range, the strength will decrease.

[0026]

In the present invention, the desired effect can be obtained only by using brucite and pulp at the same time. Furthermore, this effect is further clarified by fine particles and pearlite. When attempting to extrusion-mold a cement composition that does not use asbestos, the molding process itself becomes a problem rather than the strength of the resulting molded body. That is, it is a phenomenon that the surface smoothness of the molded body is poor, the extrusion pressure is increased to make it difficult to extrude, or the cement composition is clogged in the extruder to make extrusion impossible.

In order to prevent such a phenomenon from occurring,
It is necessary for the cement composition to maintain sufficient fluidity even under high pressure in the extruder. For that purpose, it is important to completely disperse each composition and to retain the added water in the composition even under high pressure. Like asbestos, brucite improves the fluidity of clay in the form of water added to it, and is excellent in shape retention, but because it does not have a hollow structure like asbestos, its water retention is slightly inferior. It does not show sufficient extrudability. On the other hand, pulp also has a large amount of water retention due to the hydrophilicity of the surface, but it is somewhat inferior in water retention under high pressure, so that water is separated from the composition during extrusion (breathing), and extrudability is deteriorated. Due to the difficulty of dispersion, the surface smoothness of the molded product may deteriorate.

However, when pulp and brucite, each of which exhibits insufficient performance by itself, coexist at the same time, brucite assists the dispersion of pulp and the water retention under high pressure becomes sufficient. It has been found that the formability is remarkably improved. Generally, pulp is treated as a fiber reinforcing material in cement compositions, but the present invention considers the effect on extrusion formability as the first consideration.

The fine particles and pearlite assist the effect of improving the moldability of the pulp and brucite. Although pearlite contributes to the weight reduction of the molded body, even if the weight reduction is unnecessary, the use of a small amount improves the moldability. Of course, when aiming for weight reduction, the moldability of the pearlite of the present invention is remarkable because the moldability is likely to deteriorate.

[0030]

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Examples 1 to 5, Comparative Examples 1 to 3 and Reference Example (1) According to the formulation (parts by weight) shown in Examples and Comparative Examples, raw materials other than water are uniformly mixed with an Erich mixer. (2) Add water and mix. (3) Knead thoroughly with a kneader. (4) The raw material is put into a vacuum extruder and extruded into a cross section of 12 × 250 mm. (5) Steam cure the uncured extrusion molded product at 70 ° C. for 5 hours. (6) Autoclave cure at 160 ° C x 4 hr. However, the high-density product is not subjected to autoclave curing, and after steam curing, it is allowed to stand in the room as it is for 7 days (Examples 4, 5 and Comparative Example 3). (7) Cut to the specified size. (8) Completely dry at 105 ° C for 24 hours.

[0031]

[Table 1]

Table 2 shows the results of measuring the extrusion pressure during extrusion molding and the physical properties and workability of the obtained cement molded product.

[0033]

[Table 2]

Each measurement was carried out by the following method. (1) Extrusion pressure; The pressure of the resistance part from the barrel of the extruder to the mold was measured by installing a Bourdon tube pressure gauge immediately before the taper (kg / cm ² ) chair. (2) Specific gravity; measured after being left for 24 hours after drying. (3) Bending strength: It was cut in a width of 40 mm and a length of 160 mm parallel to the extrusion direction, dried and left for 2 (kg / cm ² ) 4 hours. This sample was supported at 100 mm intervals, and a load was applied to the center of the sample at a speed of 0.5 mm / min for measurement. (4) Nailability; Measured after being left for 24 hours after drying. A long product was cut into 300 mm, and a 2.5φ gypsum board nail was struck at a position 30 mm from the cut surface and 25 mm from the product width end surface (stainless steel cloth screen nail 13 × 45). ⊚: Lightly hit, no abnormality in the sample. ○: The resistance to drive is strong, but there is no abnormality in the sample. Δ: A crack is generated on the back surface of the sample. ×: The sample breaks. (5) Surface smoothness; visual observation ◯: Smooth. ×: Small irregularities are noticeable.

The footnotes in Table 1 above are as follows: (1) Ordinary Portland cement (2) Average particle size 0.45 mm Particle size distribution 0.15 to 1.3 mm is 88% Density 0.196 g / cm ³ Name Pearlite perlite structure Independent porous foam structure (3) Chrysotile Asbestos-6D (4) Hardwood pulp (5) Daiwa Spinning Co., Ltd. "Mercury" 3mm (6) Kuraray Co., Ltd. "RKW1.82 * 3" (7) Taiheiyo Metal Co., Ltd. "Pamco Fiber" (8) Methylcellulose, Shin-Etsu Chemical Co., Ltd. "Metroses" 90SH-30000 (9) Asahi Glass Co., Ltd. (10) Kao Co., Ltd. "Mighty # 150" (11) Hayashi Kasei Co., Ltd. "Tough Mag" (12) Sumikin Bussan "Sumiselco" Co., Ltd.

The physical property values in the above footnote (2) are based on JIS
According to A 5007 "Perlite", it was obtained as follows. Particle size distribution 0.037 mm (400 mesh) to 2.4 mm (8 m
Among the sieves up to esh), 5 or more types of sieves corresponding to each sample were used for classification. Average particle size frequency cumulative (weight% passing through mesh) 50% (weight basis) particle size (mesh size mm) Ratio of particle size 0.15 to 1.3 mm Grain from frequency cumulative value of particle size 1.3 mm Subtracting the cumulative frequency of 0.15 mm diameter. Density The aggregate weight when the aggregate is put in a specified container divided by the volume.

[0037]

The cement composition for extrusion molding of the present invention is
Even if harmful asbestos is not used, the extrusion pressure during extrusion molding is low, the moldability is excellent, and the surface smoothness,
It enables the production of cement compacts with excellent bending strength and workability such as nailing in the case of low density products.

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Claims (2)

[Claims] 1. A cement composition for extrusion molding, containing 1 to 30 parts by weight of brucite and 1 to 40 parts by weight of pulp with respect to 100 parts by weight of cement. 2. The composition according to claim 1, which contains fine particles and / or perlite having a porous closed cell structure.