JPH04243943A - Light-weight high-strength asbestos-free composition for extrusion molding - Google Patents

Abstract

PURPOSE:To provide a composition for the extrusion molding of an asbestos-free article having light weight and high strength. CONSTITUTION:The objective asbestos-free composition for extrusion molding is composed of solid materials such as ordinary Portland cement as a hydraulic binder, wollastonite or pulp as reinforcing fiber, fine quartzite, crushed light- weight concrete foam cured in autoclave, methylcellulose as a thickener, etc., and a liquid material such as water. The composition is useful for the extrusion molding of an asbestos-free building material having light weight and high strength.

Description

[Detailed description of the invention]

0001

FIELD OF THE INVENTION This invention relates to compositions for lightweight, high strength, asbestos-free extruded building materials.

0002

[Prior Art] Extrusion-molded building materials obtained by extrusion molding are widely used mainly for exterior wall materials, and the manufacturing methods include hydraulic binders such as cement and slag, asbestos, pulp, etc. A compound containing reinforcing fibers and thickeners such as methylcellulose is extruded using an extruder while being shaped, and the product is obtained by steam curing at normal pressure or high temperature and pressure (Japanese Patent Laid-Open No. 57-77058). Official gazette, Japanese Patent Publication No. 5
7-3755).

[0003] Among these conventional compositions, asbestos in particular has been an essential component from the viewpoint of flow characteristics and shape retention of mortar for extrusion. However, since asbestos fibers are depleted as a resource and are harmful to the human body, there is a desire to develop a composition that has fire resistance and can be extruded without containing asbestos fibers. For this purpose, a manufacturing method in which pulp fibers and ferrosilicon dust are used for extrusion molding (Japanese Unexamined Patent Publication No. 1-96050) or a method in which surfactants, lubricants, and plasticizers are adsorbed onto the surface of beaten cellulose fibers is used. A method of forming an extrusion molded product by adding (JP-A-1-141849)
No. 2) has been proposed.

However, the previous compositions had problems in extrusion moldability, such as a change in fluidity during extrusion due to the pozzolanic nature of the ferrosilicon dust, and clogging was likely to occur. In the latter composition, the dispersion of cement, fine aggregate, etc. was poor, and there were problems with reduced strength and fire resistance. On the other hand, a proposal has been made regarding an extrusion molding composition for autoclave curing, which is characterized by having an asbestos-free composition and containing a hydraulic binder, reinforcing fibers, and crystalline fine silica stone.
93446), but when the weight was reduced, the strength was significantly reduced, which was a problem.

[0005]

[Problems to be Solved by the Invention] The present invention solves problems that could not be achieved with the prior art, namely, products that do not contain asbestos and can be extruded, and that can also be formed into products with complex shapes such as hollow shapes or surface patterns. The object of the present invention is to obtain a composition that can be produced, is lightweight, and has high strength.

[0006]

SUMMARY OF THE INVENTION The present invention provides an autoclave-cured lightweight cellular concrete in an asbestos-free extrusion composition containing a hydraulic binder, reinforcing fibers, and crystalline finely divided silica stone. Contains pulverized material. The details of the present invention will be explained below.

In the present invention, commercially available ordinary Portland cement, alumina cement, etc. are used as the hydraulic binder. These hydraulic binders generally have a weight average particle size of 20 to 30 μm. As the reinforcing fiber, the type is not specified as long as it is a reinforcing fiber, but fibers that have been generally used for reinforcing cementitious materials can be used, and asbestos may not be used. That is, inorganic fibers such as alkali-resistant glass fibers, carbon fibers, wollastonite, various natural fibers, and synthetic fibers can be used. The amount of reinforcing fiber used is generally 0.5 based on the total solid content.
Although it is used in an amount of up to 5% by weight, it is not preferable to add more than 4% when fire resistance is required for organic fibers such as pulp and rayon.

[0008] Ultrafine powder of crystalline silica stone has a weight average particle size of 5 μm.
Those smaller than m are preferable, and those containing many particles smaller than 1 μm are especially preferable from the viewpoint of the fluidity characteristics of the kneaded product. Those having a weight average particle diameter of 5 μm or more are not preferable because they are not ultrafine powders and the fluidity of the kneaded product and the shape retention of the green sheet after extrusion are poor. When ultrafine powder of amorphous silica stone is used, it is pozzolanic and can be mixed with water.
It starts to set in 0 to 60 minutes and has a short pot life, making it unusable for practical use.

The amount of crystalline ultrafine silica stone added is preferably 5 to 70% by weight of the total solids, and if it is less than 5%, the addition of ultrafine powder may affect the flow characteristics of the kneaded product and the shape retention of the green sheet. It is difficult to express the effect, and if it is added in a large amount exceeding 70%, the amount of the hydraulic binder added becomes small, making it difficult to develop the strength of the molded product after curing. As the autoclave-cured lightweight cellular concrete, it is generally possible to use one having an absolute dry specific gravity of 0.5, which is crushed with a crusher such as a jaw crusher and then classified with a sieve or the like. 5m as maximum particle size
It is preferably at most m, particularly preferably at most 2 mm. If it exceeds 5 mm, not only will extrusion moldability become difficult, but shape retention will also deteriorate. Further, the amount added is preferably 5 to 40% by weight, particularly preferably 15 to 25% by weight. If it is less than 5%, hardening for weight reduction will be small, and if it exceeds 40%, extrusion moldability will become difficult.

[0010] The composition of the present invention may also contain 1% of the total solid content.
Inorganic additives such as aluminum hydroxide and bentonite can also be added in a proportion of up to 30% by weight. When a thickener is used in the present invention, water-soluble polymers such as methyl cellulose, polyvinyl alcohol, etc. can be used as the thickener. The amount used is generally 0.1 to 2% by weight based on the total solid content.

[0011] As the surfactant, anionic, cationic, and nonionic surfactants can be used. In particular, anionic surfactants such as sodium higher alcohol sulfate and nonionic surfactants such as nonylphenol ethylene oxide adducts are used. Preferably, the amount added is 0.0 based on the total solid content.
1 to 0.3% by weight is suitable. If it is less than 0.01% by weight, the dispersion of fine silica, pulp, water, etc. will not be improved;
If it exceeds % by weight, it inhibits the hydration reaction of cement, which is not preferable.

[0012] The molding water should be 20% of the total solid content.
It is preferable to add ~40% by weight; if it is less than 20%, it will be difficult to make the absolute dry specific gravity of the product 2.0 or less;
If it exceeds 0%, the strength of the resulting product, such as bending strength, will decrease. The mortar blended, mixed, and kneaded in this manner is extrusion molded, and if necessary, primary curing is performed at 40 to 80° C. under saturated steam pressure to obtain the handling strength of the molded product. Then, if necessary, this is cured at high temperature and high pressure using an autoclave. The saturated steam temperature at this time is 110-200
°C is preferred

[0013]

[Examples] The present invention will be explained below with reference to Examples and Comparative Examples, but the present invention is not limited thereto. Table 1
Table 1 shows the compositions of Examples and Comparative Examples and the results of absolute dry specific gravity and bending strength tests of the panels obtained.

The raw materials and extrusion molding equipment used in each example are as follows. Raw materials Cement: Union ordinary Portland cement pulverized silica: Toyane silica ultra-finely pulverized product (weight average particle size 2-3 μm) Silica powder: Toyane silica pulverized product (weight average particle size 20
μm) Methylcellulose: Shin-Etsu Chemical Co., Ltd. “Metrose 90”
SH3000" Surfactant: Nonylphenol ethylene oxide adduct Pulp: Softwood bleached pulp open-cotton wollastonite: Chemolite aluminum hydroxide from India: Commercially available from Nippon Light Metal Co., Ltd., and cured in an autoclave.

[0015] Pulverized lightweight cellular concrete: maximum particle size 1.2 mm, (hereinafter referred to as ALC powder) average particle size 0.
25mm Lightweight aggregate: Obsidian pearlite No. 1 Mixing device: Eirich mixer manufactured by Nihon Eirich Co., Ltd. Kneading device: Kneader
Extrusion molding equipment: "MV-FM-200-1 type" manufactured by Miyazaki Iron Works In addition, in Examples 1 to 3 and Comparative Examples 1 to 2, each raw material was according to Table 1, cement, ultrafine silica stone, wollast After thoroughly stirring and mixing powders such as night, pulp fiber, aluminum hydroxide, ALC powder, lightweight aggregate, and methyl cellulose, liquids such as water and surfactants were added and kneaded. Thereafter, this was molded into a panel having the cross-sectional shape shown in FIG. 1 using an extrusion molding machine. This molded body was first cured for 6 hours at 60° C. under saturated vapor pressure, and then cured in an autoclave at 170° C. for a holding time of 1 hour. The pressure increase process and the pressure decrease process are 80
It was carried out at °C/h. The results are shown in Table 1.

[0016]

[Table 1]

*1 Extrusion moldability refers to whether or not a predetermined molded product can be obtained when extrusion molding is performed using a die having the shape shown in FIG. *2 The bone-dry specific gravity and bending strength of the material are determined using a hollow extrusion molded product with the shape shown in Figure 1.The width 40 mm x length 50 mm x thickness 12 m is determined so that the orientation direction of reinforcing fibers is the same as the longitudinal direction.
A solid sample of m was cut out, and the bending strength of the material was determined using an effective span of 400 mm and a bisector point test. *3 The absolute dry specific gravity was determined from the weight and volume of the test specimen placed in a dryer at 105° C. for 48 hours.

Material bending strength*
4 Specific strength = ────────, index for strength comparison at the same absolute dry specific gravity
(Absolute dry specific gravity) 2 As a result, all the Examples and Comparative Examples showed good extrusion moldability and molded bodies were obtained. In Examples 1 and 2 using ALC powder and finely divided silica stone, the specific strength, which is an index for strength comparison at the same absolute dry specific gravity, is 80 or more, and when the absolute dry specific gravity is 1.50, the material bending strength is 1.
80 (kg/cm2). On the other hand, Comparative Example 1 using silica powder and ALC powder,
Among Comparative Example 2 using fine silica powder and lightweight aggregate and Comparative Example 3 using silica powder and lightweight aggregate, Comparative Example 2 has the highest specific strength of 68.9, but the absolute dry specific gravity is 1.50
In this case, the bending strength of the material was only 154 (kg/cm2), which was 26 (kg/cm2) at the same absolute dry specific gravity as in Examples 1 and 2.
It can be seen that there is a large difference (/cm2).

[0019]

[Effects of the Invention] The present invention provides a lightweight and high-strength asbestos-free extrusion molded product by using crystalline finely divided silica stone and autoclave-cured lightweight cellular concrete pulverized material as constituent components. be able to.

[Brief explanation of the drawing]

[Figure 1] Cross-sectional view of extruded product

Claims (1)

[Claims] 1. An asbestos-free extrusion molding composition comprising a hydraulic binder, reinforcing fibers, finely divided crystalline silica stone, and pulverized lightweight cellular concrete cured in an autoclave.