JPS6330381A - Manufacture of lightweight cement product - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field 1] The present invention relates to a method for manufacturing lightweight cement products by extrusion.

[Background technology]! lli quantity cement products by extrusion molding 11! Before the molding process, a cement molding material is prepared by blending aggregate and reinforcing fibers with cement, as well as lightweight aggregate and kneading this with water. This can be done by passing it through. Cement products can be made lighter by using IT aggregate, but conventionally used lightweight aggregates include hard microscopic hollow spheres such as up-grown perlite, expanded polystyrene, glass balloons, and thermosetting resin hollow foam. . However, these had the following drawbacks.

In other words, if pearlite is used as an aggregate, pearlite is likely to be destroyed during mixing when preparing cement molding materials or during extrusion molding, making it difficult to achieve sufficient weight reduction, and the extrusion molding machine and There is a problem that the mold is easily worn out.

In addition, if pulp or common aluminum is added as reinforcing fibers to the cement molding material containing pearlite, the flowability of the cement molding material will deteriorate, resulting in flow fluctuations at thin irregularly shaped parts and edges in the extrusion mold. 9) There is a risk that the linearity of the product may deteriorate. Therefore, a sufficient amount of a fibers and pulp cannot be blended, and a relatively inflexible, hard cement product with a slightly high specific gravity is produced.

In addition, when using expanded polystyrene as a lightweight aggregate, the expanded polystyrene has a particle size (0.5~2 mm) of 500 μ~
Because it is formed relatively large (2000μ), the hardness of the kneaded cement molding material becomes high, and pulp and aJI are added to the cement molding material, as in the case of pearlite and l1ffJ.
If large amounts of reinforcing fibers are mixed in, the flowability of the cement molding material will deteriorate, and flow fluctuations will likely occur at thin irregularly shaped parts and edges in the extrusion mold, leading to material breakage and damage to the cement product. There is a risk that linearity may deteriorate.

In addition, since the particle size of foamed polystyrene is large and it is highly elastically deformable, the foamed polystyrene is compressed by the molding pressure when extruding the cement molding material, and then returns to its elastic state when the molding pressure is released. However, foamed polystyrene tends to protrude on the surface of cement products, and cracks tend to occur due to internal distortion in the vicinity of foamed polystyrene. Therefore, in order to prevent these problems, a large amount of water is added to the cement molding material. Attempts are made to improve fluidity and lower molding pressure, but
With this product, the shape retention after extrusion molding is insufficient, making it difficult to manufacture complex shaped products, and the large amount of mixed water makes the cement matrix part brittle, making it difficult to maintain sufficient strength. you won't be able to get it. In order to improve the fluidity of the cement molding material, it is conceivable to mix a large amount of a molding aid, but adding a large amount of a molding aid is uneconomical and causes an increase in cost.

Furthermore, if hard microscopic hollow spheres such as glass balloons or thermosetting resin hollow foams are used as lightweight aggregates, these hard objects are relatively brittle, so they are subject to high shear forces during kneading during the preparation of cement molding materials. It is easily destroyed by the action, making it difficult to achieve sufficient weight reduction. For this reason, the cement molding material is kneaded so as not to apply high shearing force, but the dispersibility of the hollow spheres becomes insufficient and defects in the cement product are likely to occur.

[Object of the Invention] The present invention has been made in view of the above points, and provides a lightweight cement product that has a high light weight effect, less occurrence of defects, excellent freeze damage resistance, and excellent formability. The purpose is to provide a manufacturing method.

[Disclosure of the Invention] However, the method for manufacturing a lightweight cement product according to the present invention is as follows:
Adding aggregate and reinforcing joints to cement, the grain size is 1~
The method is characterized in that a cement molding material is prepared by blending a thermoplastic resin hollow foam with a size of 100μ and an expansion ratio of 20 to 100 times, and this is extruded and then cured. Detailed explanation.

Cement molding materials are prepared by adding hollow foam and other molding aids such as methyl cellulose to a cement mixture of cement, aggregate and reinforcing fibers, and then adding water and mixing uniformly. Here, the amount of the hollow foam is 0.05 to 3 parts by weight per 100 parts by weight of the cement mixture, and the amount of the molding aid is 100 parts by weight of the cement mixture! It is preferable to set the amount to 0.2 to 1.5 parts by weight, and any cement such as Pol F land cement can be used.
In addition, silica powder and e! , fly ash, granulated blast furnace slag, gypsum, etc. can be used.

As reinforcing fibers, inorganic fibers such as asbestos and lath fibers,
Organic fibers such as vinylon fibers, polypropylene fibers, and pulp can be used, and among these, synthetic fibers such as polypropylene fibers and polypropylene fibers preferably have an AM value of 4III11 or more in view of the reinforcing effect. The blending amount of these reinforcing fibers is preferably set at 3 to 15 parts by weight per 100 parts by weight of the cement mixture.

If it is less than 3 parts by weight, the reinforcing effect will be insufficient;
If the amount exceeds 5fi parts, the formability will decrease and the reinforcement N&
If the fibers are particularly organic fibers, the cement product will no longer be quasi-inflammable.

Further, as the hollow foam, a thermoplastic U (oil foam) is used, and among them, one formed of a polyvinylidene chloride resin is preferably used.

This hollow polyvinylidene foam was developed in Japanese Patent Application Publication No. 4
It can be obtained by foaming the material provided in Japanese Patent No. 9-44094, for example, "Matsumoto Microspheres" manufactured by Matsumoto Yushi Pharmaceutical Co., Ltd. can be used. Polyvinylidene chloride-based products are easier to foam into microscopic hollow spheres than polystyrene-based products; in other words, it is difficult to obtain foamed polystyrene with a particle size of 0.5 mm (500 μ) or less. However, since polyvinylidene chloride-based products can be easily obtained in the form of microspheres with a particle size of 0.1 mm (100μ) or less, polyvinylidene chloride is used as a hollow foam of thermoplastic resin in the present invention. It is preferable to use a hollow foam with a small particle size of 1 to 100μ.If the particle size is larger than 100μ, the purpose of the present invention will be achieved as described later. I can't. In addition, it is difficult to obtain a hollow foam with a particle size of 1 μm without grooves, and the particle size is 1 μm.
If it is less than that, the effect of reducing the weight of cement products will be insufficient.

In addition, if the hollow foam is made of polyvinylidene chloride, it has less elastic recovery than expanded polystyrene, and the elastic recovery due to the release of molding pressure after extruding the cement molding material can be reduced. From this point of view, it is preferable to use a polyvinylidene chloride-based hollow foam as the thermoplastic resin hollow foam, and furthermore, the hollow foam should have an expansion magnification (:a magnification (true magnification)) of 20 to 100 times, Preferably it is 30 to 70 times.If the foaming ratio exceeds 100 times, the purpose of the present invention cannot be achieved, as will be described later.On the contrary, if the foaming ratio is less than 20 times, the purpose of the present invention cannot be achieved. If so, the effect of reducing the weight of the cement product cannot be fully obtained, and a large amount of compounding is required to reduce the weight, making it uneconomical.

As described above, a cement molding material is prepared by mixing cement with aggregate, reinforcing fibers, hollow foam, and other additives, and mixing it with water. It is best to use a mixer with high-speed stirring blades at rpm or higher to ensure uniform mixing, and the amount of mixing water should be set at 35 to 60% by weight based on the total solid content of the cement molding material. The cement molding material thus prepared should preferably have a hardness of 7 or less on a clay hardness scale. This cement molding material is then fed to an extrusion molding machine.
Extrusion is performed by passing the material through a mold.

This extrusion molding has a molding pressure of 10 kg/am2.
Below, it is preferable to set it to 8 kg/am2 or less. After extrusion molding in this way,
Cement products can be obtained by curing and hardening cement extrudates, but curing is carried out by heat curing at 70°C or higher, followed by autoclave curing at a high temperature and pressure of 2 to 6 atm in the final stage. good.

Therefore, in the present invention, thermoplastic a is used as a lightweight aggregate.
Unlike pearlite or hard micro-hollow sphere pairs, hollow foam is less susceptible to shearing forces during kneading and extrusion molding to prepare cement molding materials due to its plasticity. It is possible to reduce the risk of breakage due to shearing force during the process, fully exhibit the effect of weight reduction, and mix the cement molding material at high speed to prepare the cement molding material to have a uniform composition. be able to. As described above, since the hollow foam used in the present invention is difficult to break, the broken portion does not become a strength defect, and there is no need to add an excessive amount of reinforcing fiber to strengthen the foam.

In addition, in the present invention, the foaming ratio is 1 as a hollow foam.
00 times or less, the foaming ratio is not too large and the strength does not decrease, and in this respect, it is possible to prevent the hollow foam from being destroyed. The foaming ratio of the body is 20 times or more, and the weight reduction effect can be fully obtained.

Furthermore, in the present invention, the particle size of the hollow foam is 100 mm.
Even though the hollow foam is made of thermoplastic resin, the particle size is small, so the molding pressure after extrusion molding is low. Upon release, the hollow foam greatly recovers its elasticity (
There is no risk of springback (springback), and it is possible to obtain sufficient strength by preventing defects such as internal distortion and cracks from occurring in cement products. Also, the particle size is 100μ
The following micro hollow foam of the present invention has a small particle size and is slippery, and can improve the flowability of cement molding materials prepared as mixed materials, and can be used as a cement molding material even in areas with relatively little mixing water. is sufficiently soft (can be formed, therefore, the molding pressure during extrusion molding can be lowered, and in this respect, the elastic recovery of the hollow foam due to the release of molding pressure after extrusion can be kept small) In addition to this, high-speed extrusion molding is also possible.

Furthermore, since the flowability of the cement molding material is improved in this way, it is possible to make the flow of the cement molding material smooth at the thin irregularly shaped parts and edges of the extrusion mold. This can reduce the occurrence of material breakage and poor linearity.In particular, in the case of the present invention, which uses hollow foam with a small particle size, relatively long synthetic fibers are added to the cement molding material as reinforcing fibers. In order to maintain the high flowability of the cement molding material even when it contains fibers and pulps, it is possible to blend long synthetic fibers and pulps in sufficient amounts to achieve excellent strength and toughness as well as to be lighter. Cement products can be easily obtained as complex irregularly shaped products.In addition, because the hollow foam has a microscopic particle size, the orientation of the reinforced #& miscellaneous material is fully demonstrated, and the reinforcement with reinforcing fibers is effective. In addition, the voids between the hollow foams with small particle sizes are small and the voids within the cement product are also small, so the hollow foams
Although the effect of i-ization can be fully exhibited, the decrease in strength can be suppressed to a small level.

In addition, in cement products containing micro hollow foams with a particle size of 1 to 100 μm, the hollow foams form a large number of closed cells, and these air bubbles generate stress during freezing and thawing. It is possible to sufficiently alleviate the damage caused by freezing and improve frost damage resistance. In the case of hollow foams with large particle diameters, such as expanded polystyrene, internal distortions and cracks occur due to elastic recovery, as mentioned above, and stress during freezing and thawing is concentrated in these areas, resulting in poor freeze-damage resistance. However, in the present invention, although the thermoplastic resin hollow foam is used, the particle size is fine, so there is no internal distortion or cracking due to elastic recovery, and the frost damage resistance is improved. There is no problem of decrease in . Moreover, in the present invention, as mentioned above, long fibers and pulps can be sufficiently blended into the cement molding material without impairing fluidity, and these can also enhance stress relaxation during freezing and thawing. It can improve frost damage resistance. Furthermore, when using pearlite as a lightweight aggregate, pearlite often has a high water absorption rate, and the water absorption rate of cement products also decreases, and it is easy to receive stress from freezing and thawing, making it difficult to improve frost damage resistance. Since the thermoplastic resin hollow foam used in the present invention can form closed cells, there is no such problem of water absorption, and the frost damage resistance can be easily improved. In addition, since pearlite boxes have high water absorption, it is necessary to increase the amount of water mixed in order to improve the fluidity of the cement forming material, and as a result, if the temperature equilibrium with the external atmosphere is disrupted during the curing process, the cement (Efflorescence is likely to occur on the surface of the product, and even in the case of coarse expanded polystyrene, some efflorescence is likely to occur in the cement matrix and amn content, but as in the present invention, micro hollow foam of thermoplastic resin When using a cement molded product, a large amount of fine independent hollow parts are contained in the cement molded product, which suppresses the movement of moisture in the capillary tubes, and the occurrence of efflorescence as seen in the examples below. However, if efflorescence occurs or protrusions appear on the surface due to elastic recovery, as in the case of coarse-grained expanded polystyrene, the surface of the cement product should be cut or buffed. It is necessary to perform polishing, etc., and there are problems with the adhesion of the paint film decreasing and peeling of the paint film at this cutting and polishing part.
The present invention, which does not generate efflorescence or protrusions, does not have such problems.

Next, the present invention will be further explained by examples.

t 1-6 1-6 Cement molding materials were prepared by mixing and kneading the formulations shown in Table 1. Here, as the "microsphere" in Table 1, "Matsumoto Microsphere" manufactured by Matsumoto Yushi Pharmaceutical Co., Ltd. was used.

Further, the hardness of the cement molding material was measured using a clay hardness meter, and the results are shown in Table 2. By extrusion molding this cement molding material at the molding pressure shown in Table 2, an extrusion molded product A having an irregular cross section shown in FIG. 1 was obtained. The appearance of this extruded product A was inspected, the linearity was measured, and the results were
Shown in the table. Here, in Table 2, "linearity of the molded product" is shown by measuring the deviation dimension of the side end portion of the extrusion molded product in the extrusion direction 3111. Next, this extruded product A was subjected to moist heat curing and autoclave curing under the conditions shown in Table 2 to obtain a lightweight cement product.

Various properties of the lightweight cement product thus obtained were measured, and the results are shown in Table 2. Here, in Table 2, "freeze damage resistance" was measured in accordance with the freeze-thaw test in ASTM C-666A method. In Comparative Example 3 and Comparative Example 4 using glass balloons, the cement molding material is hard and requires high molding pressure.
Material breakage occurred during extrusion molding, the straightness of the extruded product was poor, efflorescence was likely to occur on the surface of Toda cement products, and the frost resistance was also poor. In Examples 1 to 5 using microspheres with an average particle size of 40 μ and an average expansion ratio of 60 times, and Example 6 using microspheres with an average particle size of 30 μ and an average expansion ratio of 30 times, these It is confirmed that no problems occur. In addition, even if Micros 7E7- is used, in Comparative Example 1 with a foaming ratio of 110 times, the weight reduction effect will be reduced due to the destruction of the microspheres, and the frost damage resistance will be reduced. It is confirmed that

Furthermore, in Comparative Example 5, where the foaming ratio is 10 times, it is not possible to reduce the specific gravity of the cement product, and the weight reduction effect cannot be sufficiently obtained. It is confirmed that as in Example 6, it is necessary to increase the amount of microspheres blended, resulting in poor economic efficiency.

Further, the cement molding materials of Comparative Example 2, Comparative Example 3, and Example 1 were evaluated for their extrudability. In the test, the entrance shown in Figure 2 was φ16 (cross-sectional area 2 cm).
), the cement molding material is put into a cylinder B with an outlet of φ11, and the cement molding material is extruded as an extrudate using an extrusion rod C of φ16. At this time, the extrusion flow It Q (am3/win) is 2. ．．
We investigated how the extrusion pressure P (kgf/0m2) per unit area changes when changing from 4.6.10. The results are shown in Table 3, and the graph shown in FIG. 3 shows these results. That is, the results of Comparative Example 2 are shown in the graph of FIG. 3(a), the results of Comparative Example 3 are shown in the graph of FIG. 3(b), and the results of Example 1 are shown in the graph of FIG. 3(c). However, in Comparative Examples 2 and 3, the flow rate Q
The relationship between P and pressure P is negative, and that of Example 1 is positive. This means that in Comparative Example 2 and 3, the discharge rate does not increase even if the extrusion pressure is increased, that is, the aggregate tends to be compressed, resulting in unstable forming flow, but in Example 1, the discharge rate does not increase even if the extrusion pressure is increased. In some cases, the extrusion pressure is increased (which increases the amount of extrusion), which means that a stable molding flow is achieved.

[Effect of the invention 1 As described above, the present invention combines cement with aggregate and reinforcing fibers, has a particle size of 1 to 100μ, and has an expansion ratio of 20 to 1.
The cement molding material 31i is made by blending a hollow foam of thermoplastic resin with a weight of 0.00 times, and this is extruded and then cured, so this hollow foam is difficult to break and has a lightweight effect. It is possible to obtain a cement product that fully exhibits the properties of the hollow foam, and it is also possible to obtain a cement product that has a small elastic recovery after extrusion molding and has fewer defects. does not reduce the flowability of cement molding materials and does not reduce moldability such as material breakage or deterioration of linearity, and also improves the freeze damage resistance of cement products by forming closed cells with hollow foam. It is something that can be done.

[Brief explanation of the drawing]

Figure 1 is a diagram showing an irregular cross section of an extruded product, Figure 2 is a perspective view of a cylinder used for evaluating moldability, and Figure 3 (a).
(b) and (c) are graphs showing the relationship between the flow rate of cement molding material and extrusion pressure. Agent Patent Attorney Ishi 1) Ai 7 Figure 1 Figure 2

Claims (4)

[Claims] (1) Prepare a cement molding material by blending aggregate and reinforcing fibers with cement, as well as thermoplastic resin hollow foam with a particle size of 1 to 100μ and a foaming ratio of 20 to 100 times, and extrude it. A method for manufacturing a lightweight cement product characterized by curing after molding. (2) The method for manufacturing a lightweight cement product according to claim 1, wherein the hollow foam is made of polyvinylidene chloride resin. (3) The hollow foam is added to the cement molding material from 0.05 to 100 parts by weight of the total amount of cement, aggregate, and reinforcing fibers.
3. The method for producing a lightweight cement product according to claim 1 or 2, characterized in that the content is 3 parts by weight. (4) The reinforcing fibers are blended into the cement molding material at a ratio of 3 to 15 parts by weight based on 100 parts by weight of the total amount of cement, aggregate, and reinforcing fibers. A method for producing a lightweight cement product according to any one of items 1 to 3.