JP2540190B2 - Method for manufacturing lightweight cement compact - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a cement molded product, particularly a method for manufacturing a lightweight cement molded product used for interior or exterior building materials.

(Prior Art) Light-weight cement compacts are used as building materials for interior and exterior such as wall materials and ceiling materials. As a method for manufacturing a lightweight cement compact, a method of generating bubbles when water is added to each component of the cement composition and mixing, and a compact using a cement composition containing a lightweight aggregate are prepared. There is a way to do it. Among these, as a method of generating bubbles, a method of mixing a foaming agent such as an air entrainment (AE) agent and a surfactant and foaming by stirring; mixing a substance that generates a gas such as hydrogen peroxide by decomposition is mixed. In addition, there is a method of foaming by using gas generated by decomposition of the substance. However, when a mud-like cement composition containing fine bubbles generated in this way is vacuum extrusion-molded, most of the bubbles disappear due to deaeration in the decompression zone of the extruder. Therefore, a low-density cement compact cannot be obtained.

In the method of using the above lightweight aggregate, as the lightweight aggregate, relatively fine-grained and low specific gravity aggregates such as pearlite, shirasu balloon, and lapilli are used. However,
When a cement composition material containing these is pressed and kneaded in an extruder, the aggregate is easily crushed, so that a lightweight cement compact cannot be obtained. JP-A-56-17965 and JP-A-56-17967 disclose a cement composition containing alkali-resistant glass fiber (ARG), charcoal and pulp in addition to the above-mentioned pearlite, shirasu balloon, and gravel. The thing is disclosed. The above-mentioned glass fiber is added as a reinforcing fiber, and charcoal and pulp are added for the purpose of preventing the crushing of the lightweight aggregate and the damage of the glass fiber when the respective materials of the composition are kneaded. Crushing and damage are likely to occur due to strong kneading under conditions of low water content (necessary for maintaining the shape of the uncured compact). However, charcoal and pulp contain lignin and resin, which adversely affect the hardening reaction of cement.
In other words, when the molded body is cured at room temperature or in a steam atmosphere, the strength of the molded body obtained is insufficient, so treatment at high temperature and high pressure using an autoclave is necessary. Becomes

In the case of manufacturing the above-mentioned lightweight cement molded product, particularly in the case of molding by extrusion molding, it is also required that the moldability and the shape retention of the obtained uncured molded product are good. Conventionally, in the case of manufacturing a cement molded product by extrusion molding, by adding asbestos fiber, the moldability and the shape maintainability have been secured. The addition of asbestos fibers improves the strength of the molded product and also provides fire protection.
However, asbestos is designated as a specific chemical substance, and its carcinogenicity is a problem. Although a standard for use is set when manufacturing an asbestos-cement compact, a compact using a cement composition that does not contain asbestos is now desired due to the problem of dust generation during production and use.

(Problems to be Solved by the Invention) The present invention is to solve the above-mentioned conventional drawbacks, and an object of the present invention is to provide a high-strength, fireproof lightweight cement molding which can be used as a building material for exterior or interior. It is an object of the present invention to provide a method for producing a molded body which is a body and does not contain toxic asbestos.

(Means for Solving the Problem) The method for producing a lightweight cement compact according to the present invention comprises: cement, a particle size of 2 mm or less, an expansion ratio of 10 to 60 times, and 0.5 to 20 parts by weight with respect to 100 parts by weight of cement. A step of obtaining a cement composition containing expanded styrene beads, a surfactant, an inorganic aggregate mainly composed of spherical particles, a reinforcing fiber and a cellulosic admixture; and adding a plastic kneaded product obtained by kneading the cement composition. A step of extruding under pressure; and a step of pre-curing the obtained molded body at a temperature at which the styrene beads in the molded body are not thermally deformed, and then curing by wet air curing at 40 ° C. or higher. By doing so, the above object is achieved. In a preferred embodiment, the cement composition further contains sepiolite.

The cement contained in the cement composition used in the present invention includes Portland cement, blast furnace cement,
Any known cement such as alumina cement can be used.

The expanded styrene beads contained in the cement composition are beads made of a styrene polymer foam.
Such beads, for example, introduce a hydrocarbon-based gas such as propane or butane during the polymerization of styrene monomer,
After the gas is included in the obtained polymer particles, the polymer particles are heated and foamed. The particle size of the expanded styrene beads is 2 mm or less, preferably 0.5 to 1.5 mm. If the particle size is too large, the strength of the obtained molded article will be reduced. The expansion ratio of the beads is 10 to 60 times, preferably 20
~ 40 times. When the expansion ratio exceeds 60 times, when the cement composition is molded by extrusion, the beads are compressed and deformed, and their shape is recovered after extrusion, so that cracks occur in the molded body. When the expansion ratio is less than 10 times, the specific gravity of the obtained molded product increases. The expanded styrene beads are contained in an amount of 0.5 to 20 parts by weight based on 100 parts by weight of cement. If the amount is too small, the specific gravity of the obtained molded product increases, and if it is excessive, the strength of the molded product decreases.

The surfactant is used to enhance the dispersibility of each component of the cement composition during kneading / extrusion and to enhance the fluidity of the kneaded product. As such a surfactant, a surfactant generally used as a water reducing agent for cement is used. For example, naphthalenesulfonic acid-formalin condensate sodium salt, melamine-formaldehyde condensate sulfonate, aromatic polycyclic condensate sulfonate-based surfactant, higher polyhydric alcohol-based surfactant, gluconate-based surfactant There are surfactants and lignin sulfonate-based surfactants. The above surfactant is contained in an amount of 0.1 to 5 parts by weight with respect to 100 parts by weight of cement. If the amount is too small, the fluidity when the respective components of the composition are mixed is poor, so a large amount of water is required, and as a result, the strength of the resulting molded article is poor. If it is excessive, it will adversely affect the setting of cement and reduce the strength. The surfactant may be applied to the surface of the expanded styrene beads, for example, the surface of the beads may be coated.
By doing so, the dispersibility of the expanded styrene beads is further improved.

The inorganic aggregate contained in the composition is mainly composed of spherical particles. In one preferred embodiment of the invention,
The particle size of this inorganic aggregate is 0.1 to 500 μm. If the particle size is too large, the moldability during molding deteriorates. As the inorganic aggregate having the above particle size, fly ash (a pulverized coal combustion ash collected by a dust collector of a coal-fired power plant); microsilica, silica fume, spherical calcium silicate (all of which are silicon metal and ferrosilicon) Are produced as by-products at the time of production) and the like are preferable.

In another preferred embodiment, the inorganic aggregate is mainly composed of spherical aggregate having a particle size of 1 to 100 μm and having a particle size of 1 μm.
It contains ultrafine aggregate of m or less as a minor component. As the spherical aggregate among the inorganic aggregates, fly ash, spherical calcium silicate (produced as a by-product during the production of silicon metal, ferrosilicon, etc.) and the like are preferable. As the ultrafine particle aggregate, there is used an inorganic particle having the above-mentioned particle size, which can form a finely packed structure in the molding step described later and causes a pozzolanic reaction in the curing step. As such an ultrafine particle aggregate, microsilica (produced as a by-product during the production of ferrosilicon), natural pozzolan, diatomaceous earth, silica flour, aerosil, etc. are suitable.

In either case, the inorganic aggregate is used as cement.
It is contained in an amount of 10 to 100 parts by weight per 0 parts by weight. If the proportion of the inorganic aggregate in the entire composition is low, the moldability is poor,
If the amount is excessive, the strength of the obtained molded product will decrease. When the spherical aggregate and the ultrafine particle aggregate are used, the spherical aggregate is 80 to 99% by weight of the whole inorganic aggregate, and the ultrafine particle aggregate is 1 to 20% by weight. Contained in.
When using spherical aggregates and ultrafine particle aggregates in combination,
It is preferable that the below-described sepiolite is contained in the composition.

Reinforcing fibers are used to improve the bending strength and impact strength of the resulting molded product. For example, organic fibers, pulp, etc. can be used. As a material for the organic fiber, an alkali resistant material such as vinylon, polypropylene, polyethylene, acrylic resin, aramid, polyester, or carbon is suitable. The diameter of the reinforcing fiber is 1
A suitable length is 100 μm and a fiber length of 3 to 20 mm. The reinforcing fiber is contained in the composition at a ratio of 0.1 to 10 parts by weight with respect to 100 parts by weight of cement. If the reinforcing fibers are too small, the strength of the obtained molded article will be reduced. If it is excessive, the dispersibility when the materials of the composition are mixed is poor, and as a result, the strength of the resulting molded article is reduced.

The cellulosic admixture is used for the purpose of imparting a certain degree of viscosity when the composition is extruded and improving the fluidity. As the cellulose-based admixture, methyl cellulose, hydroxyethyl cellulose and the like are preferably used. This cellulosic admixture is contained in the composition at a ratio of 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight, based on 100 parts by weight of cement. If the amount is too small, the viscosity when the composition is mixed is low, and if the amount is too large, the viscosity is high.

Sepiolite is optionally contained in the cement composition. This sepiolite is, for example, (OH ₂ ) ₄ (OH)
₄ Mg ₈ Si ₁₂ O ₃₀ · 6-8H ₂ O is a magnesium silicate compound. Sepiolite is a clay mineral of a double-chain structure type, and exists in the form of fibrous, powdery, granular, plate-like, etc. Sepiolite exists in either α-type or β-type crystal structure, but it exists in the form of fibrous α
Type sepiolite (α-sepiolite) is preferably used. The fiber diameter of this fibrous sepiolite is 0.01 to 0.30
μm, preferably about 0.15 μm; and the fiber length is 1 μm or more, preferably 100 μm or more. Sepiolite is contained in the cement composition in an amount of 50 parts by weight or less, preferably 3 to 50 parts by weight, and more preferably 5 to 100 parts by weight of cement.
It is contained in a proportion of 30 parts by weight. If it is excessive, the strength of the molded product will decrease.

In order to produce a cement molded product by the method of the present invention, the same steps as conventional cement extrusion molding can be adopted. For example, first, the above cement, expanded styrene beads, a surfactant, an inorganic aggregate, a reinforcing fiber, a cellulosic admixture, and optionally sepiolite are dry blended. An appropriate amount of water is added to this to perform wet blending, and then kneading is sufficiently performed using a kneader. The obtained plastic kneaded product is introduced into an extruder having a desired mold, and extrusion molding is performed under pressure. The extruded compact having the desired shape is
It is pre-cured by curing at a temperature at which the expanded styrene beads and reinforcing fibers in the molded body do not deform or move, usually below 40 ° C. Next, this molded body is completely cured by being subjected to humid air curing (steam curing) at 40 ° C. or higher, preferably 40 to 80 ° C. The steam curing time is usually more than 5 hours. General-purpose equipment can be used for the blending step, kneading step, and extrusion molding step.

(Operation) When the above cement composition is extrusion-molded by the method of the present invention, when the water content of the kneaded material is relatively low in the extruder (for example, the water content is reduced to obtain a molded product having a complex irregular cross-section, and uncured). In the case of improving the shape retention of the molded body (1), the kneaded product has sufficient fluidity and the flow velocity becomes uniform. The extruded uncured molded product has sufficient shape retention until curing proceeds. Such good properties are due to the fact that the inorganic aggregate in the cement composition consists mainly of spherical particles.
This shows the effect of the bearing under pressure,
Since the cement composition contains the above-mentioned inorganic aggregate, expanded styrene beads and reinforcing fibers, it has excellent shape-retaining property after extrusion, and the extruded uncured compact does not lose its shape before it hardens. , And a surfactant are contained, the wettability between the respective materials of the composition (particularly the wettability between expanded styrene beads and cement) is improved, a uniform kneaded product is obtained, and the required water / It is thought that this is mainly due to the decrease in the cement ratio. When the sepiolite is contained, the sepiolite imparts thixotropy to the kneaded product. Therefore, it has good fluidity under pressure and excellent shape retention after extrusion. Since the composition further contains a cellulosic admixture, an appropriate viscosity is imparted. Even when molding is performed using a mold having a complicated irregular cross-sectional shape, the dehydration step is not required and the molding is easily performed.

The uncured extruded compact has good shape retention and does not deform during pre-curing or until it is completely cured. At the time of hardening of the molded body, 40 ℃ or more, preferably 40-80 ℃
The temperature conditions are adopted, and under such temperature conditions, the expanded styrene beads contained in the molded body are not melted by heat. The expanded styrene beads in the composition are slightly shrunk due to the pressure during extrusion, and the cohesive force of the reinforcing fibers and cement paste acts on the molded product to obtain a prestressing effect after extrusion and strengthen tensile strength. Since the obtained cured molded product contains expanded styrene beads, the molded product has a low specific gravity. Moreover, since it contains reinforcing fibers, it has sufficient strength and impact resistance. Such a molded body is suitably used as a wall material or ceiling material of a house.

According to the present invention, as described above, a lightweight and high-strength cement molded product suitable for interior and exterior building materials such as wall materials and ceiling materials can be easily manufactured without using conventional asbestos fibers. Since no asbestos fibers are used, there is no risk of carcinogenesis due to asbestos dust during the manufacturing process and use.

(Example) Hereinafter, the present invention will be described with reference to Examples.

Example 1 (A) Preparation of plastic kneaded material: Mixer for each component other than water in the cement composition of the above formulation (Eirich mixer RVO2 type: manufactured by Nippon Eirich)
And mixed at 1000 rpm for 2 minutes. After adding water to this and mixing for about 1 minute, the auger type kneader (MP-100
It was sufficiently kneaded with a mold: manufactured by Miyazaki Tekko Co., Ltd. to obtain a plastic kneaded product.

(B) -1 Preparation of flat plate cement-like compact: The kneaded product obtained in (A) was used as a flat plate trial mold (opening width 250 mm ×
Vacuum extrusion molding machine (MV-FM- with a thickness of 15 mm)
A-1; manufactured by Miyazaki Iron Works Co., Ltd.), and a flat plate sample having a width of 250 mm, a thickness of 15 mm and a length of 100 cm was prepared by extrusion molding. At this time, the extrusion pressure and the extrusion amount per unit time were measured. For the extrusion pressure, the pressure at the resistance part from the extruder's parel to the mold was measured with a brudle pressure gauge. The extrusion rate per unit time is the length (cm / min) of the flat plate sample extruded from the die tip in 60 seconds.
Was measured and calculated by the following formula.

T: Extrusion rate per unit time (l / hr) α: Cross-sectional area of die outlet (cm ² ) β: Length of extruded flat plate sample (cm / min) After placing in a steam curing room with a relative temperature of 90% or more for 6 hours (curing) to pre-cure it, steam curing for 12 hours in an atmosphere with a relative humidity of 90% or more at 60 ° C to obtain a cement compact. It was

(B) -2 Preparation of Hollow Molded Body: A hollow profile mold having an opening having the cross-sectional shape shown in FIG. 1 was attached to the same vacuum extrusion molding machine as in (B) -1, and the extrusion molding machine was fitted with the hollow molding die. (A)
The kneaded product obtained in Section (1) was supplied and extrusion molding was carried out according to Section (B) -1.

The obtained cement molded body 10 has a rectangular flat plate shape in cross section as shown in FIG. 1, and a ridge 11 having a rectangular cross section protruding laterally on one side surface in the width direction. A groove 12 into which the protrusion 11 can be loosely fitted is provided on the other side surface over the entire area in the extrusion direction. In addition, three space portions 13a, 13b, 13 having a rectangular cross section are formed in the entire area in the extrusion direction.
c is formed. The space portions 13a, 13b, 13c have the same size.

The molded body 10 has a widthwise dimension of 250 mm, a thickness of 50 mm, and a length in the extrusion direction of about 200 cm excluding the ridges 11, and each corner is chamfered in an arc shape with a radius of 3 mm. . The ridge 11 projecting from one side surface has a protrusion amount of 20 mm from the side surface and a thickness direction dimension of 20 mm at the central portion of the side surface. Each corner of the section is chamfered in an arc shape with a radius of 3 mm. The concave groove 12 formed on the other side surface has a dimension in the thickness direction at the opening of 24 mm and a depth of 22.4 mm at the center of the side surface, and each corner has an arc shape with a radius of 3 mm. It is chamfered. Each of the space portions 13a, 13b, 13c formed inside is arranged in the central portion in the thickness direction of the molded body, and the dimension in the thickness direction is 30 mm and the dimension in the width direction is 61.2 mm. There is. The spaces 13a, 13b, 13c are separated by 10 mm. Ridge 11
The space 13a adjacent to the side surface on which the
The space portion adjacent to the other side surface is 34.4 mm apart from the other side surface, and is therefore separated from the inner rear surface of the concave groove 12 arranged on the side surface by 12 mm.

The above-mentioned uncured molded body was left to cure and cured in the same manner as in (B) -1.

(C) -1 Performance evaluation of flat plate molded body: The sample obtained in (B) -1 was cut into a width of 25 mm and a length of 240 mm (cut at right angles to the extrusion direction) and put in a gear oven at 105 ° C. About 48
After drying for an hour, it was allowed to cool to room temperature. This sample is 200mm
Bending strength was measured by applying force at a bending speed of 2.5 mm / min using an autograph (manufactured by Shimadzu Corp.) at the center of the support. Bending strength is expressed by the following formula: Bending strength (kgf / cm ² ) = 3PL / 2bt ² P: Maximum load (kg / f) L: Support distance (cm) b: Width of sample (cm) c: Sample Thickness (cm) Next, after the cured molded body obtained in the item (B) -1 was left at room temperature for about 1 week, a new sample was cut into a size of 200 mm × 200 mm. The size of this sample was measured, and the specific gravity of the molded body was measured by the following formula: Specific gravity = board weight / thickness x width x length (weight is in units of g up to the second decimal point, and in units of cm) The measurement was carried out to the second decimal place.) Further, the molded body obtained in the item (B) -1 was cut into a width of 200 mm and a length of 200 mm (cut at right angles to the extrusion direction) to obtain a sample. This sample was applied to flat air-dried sand (thickness
10 cm), and a 1 kg steel ball was dropped from the height of 3 m in the center to observe whether any abnormalities were found in the sample (impact resistance test).

The results of each test are shown in Table 1. Table 1 and Tables 2 to be described later
In the item of impact resistance test of 3, the symbol ⊚ indicates that no change was observed, the symbol ◯ indicates that a crack was formed, and the symbol × indicates that the crack penetrated and the sample was divided into pieces.

(C) -2 Performance evaluation of hollow molded body: The cured sample obtained in (B) -2 was cut at a position with a length of 100 cm in the extrusion direction. In this way, two test pieces were obtained, and it was examined whether or not the fitting portion of the convex portion and the concave portion could be fitted. Table 1 shows the results.

Examples 2 to 4 Using cement compositions containing the respective components in the proportions shown in Table 1, moldings were molded and evaluated according to Example 1. Table 1 shows the results. In Table 1, aramid is Technora T-320 × 6 (fiber diameter 12 μm, fiber length 6
mm; Teijin Limited); and polypropylene fiber is PZL1
2d × 10 (fiber diameter 42μm, fiber length 10mm; manufactured by Daiwa Spinning Co., Ltd.)
Is.

Comparative Examples 1 to 2 Using a cement composition containing the components in the proportions shown in Table 1, moldings were molded and evaluated according to Example 1. Table 1 shows the results. When molding was performed using the composition of Comparative Example 2, molding failure occurred and a molded article having a satisfactory shape could not be obtained.

Examples 5 to 8 In addition to the components of the cement composition of Example 1, a composition further containing sepiolite was used to obtain a molded article in accordance with Example 1 and evaluated. Table 2 shows the ratio of each component in the composition and the test results. Among the sepiolites in Table 2, “Cerbola” is a Chinese sepiolite with a fiber length of 100 μm or more (made by Union Chemicals), and “Adeplus P” is a sepiolite with a fiber length of 10 μm or less (made by Takeda Pharmaceutical Co., Ltd.). . The same applies to Table 3.

Comparative Examples 3 to 4 Using cement compositions containing the components in the proportions shown in Table 2, moldings were molded and evaluated according to Example 1. The results are shown in Table 2. When molding was performed using the composition of Comparative Example 4, molding failure occurred, and a molded product having a satisfactory shape could not be obtained.

Examples 9 to 12 In addition to the components of the cement composition of Example 1, sepiolite was further included, and the inorganic aggregate had a fly ash having an average particle size of 20 μm (manufactured by Kandenko Kako Co., Ltd.) and an average particle size of 0.
15μm Micro Silica (Elchem Micro Silica 940
-U; SiO component 14%; made in China, Union Chemicals Co., Ltd.) was used to obtain a molded article in accordance with Example 1 and evaluated. The ratio of each component in the composition and the test results are shown in Table 3 together.

Comparative Examples 5 to 6 Using cement compositions containing the components in the proportions shown in Table 3, moldings were molded and evaluated according to Example 1. The results are shown in Table 3. When molding was carried out using the composition of Comparative Example 5, molding failure occurred and a molded product having a satisfactory shape could not be obtained.

From Tables 1 to 3, it can be seen that, when the composition of the present invention is used, a cement molded product can be obtained by extrusion molding with good moldability. The obtained uncured molded body has excellent shape retention and does not deform before being cured. The molded product obtained by curing is lightweight and has excellent bending strength and impact resistance.

(Effects of the Invention) According to the method of the present invention, a cement molded product that is lightweight, has high strength, and is excellent in fireproofness can be obtained by extrusion molding with good moldability and high efficiency. Such a cement molded product is preferably used as an interior / exterior material such as a wall material or ceiling material for a house. Since it does not contain asbestos, there is no risk of carcinogenesis due to dust in asbestos during the manufacturing process and during use.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a cement molded product obtained by the method of the present invention. 10… Hollow cement compact.

Claims (7)

(57) [Claims] 1. Cement with a particle size of 2 mm or less and an expansion ratio of 10
~ 60 times, 0.5 ~ 20 parts by weight to 100 parts by weight of cement, obtain a cement composition containing expanded styrene beads, surfactant, inorganic aggregate mainly composed of spherical particles, reinforcing fiber and cellulosic admixture 40, a step of extruding a plastic kneaded product obtained by kneading the cement composition under pressure, and pre-curing the obtained molded body at a temperature at which styrene beads in the molded body are not thermally deformed. A method for producing a lightweight cement compact, which comprises a step of curing by curing in a humid atmosphere at a temperature of ℃ or higher. 2. The method according to claim 1, wherein the cement composition further contains sepiolite. 3. The method according to claim 1, wherein the inorganic aggregate is mainly spherical aggregate having a particle size of 0.1 to 500 μm. 4. The method according to claim 2, wherein the inorganic aggregate contains a spherical aggregate having a particle size of 1 to 100 μm as a main component and an ultrafine particle aggregate having a particle size of 1 μm or less as a minor component. Method. 5. The method according to claim 1, wherein the surfactant is applied to the surface of the styrene beads. 6. In the cement composition, the surfactant is 0.1 to 5 parts by weight, the inorganic aggregate is 10 to 100 parts by weight, and the reinforcing fiber is 0.1 to 10 parts by weight with respect to 100 parts by weight of cement. The method according to claim 1, wherein the cellulosic admixture is contained in a proportion of 0.1 to 10 parts by weight. 7. The cement composition contains 0.1 to 5 parts by weight of the surfactant, 10 to 100 parts by weight of the inorganic aggregate, and 3 to 50 parts by weight of the sepiolite, based on 100 parts by weight of cement. The method according to claim 2, wherein the reinforcing fibers are contained in an amount of 0.1 to 10 parts by weight, and the cellulosic admixture is contained in an amount of 0.1 to 10 parts by weight.