JPH0150562B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field] The present invention relates to a production method that can produce fiber-reinforced cement products that do not contain asbestos at all, using a Hachietsu paper machine that has been widely used in the past to produce asbestos cement products. [Background Art] Conventionally, inorganic hardened bodies using hydraulic cement as a binder and asbestos as a reinforcing material have been widely used. However, in recent years, asbestos has come to be suspected of being a carcinogen, and various countries are investigating inorganic hardened materials that do not contain asbestos, and some of these have already been commercialized. Since asbestos cement boards have an extremely large number of uses, research into non-asbestos cement boards was carried out from an early stage, but because asbestos has such excellent advantages, it has not been possible to achieve the same quality, productivity, and cost as conventional asbestos cement boards. It can be said that there is not even a single non-asbestos cement board that has all of these features in the world. The biggest reason for this is the following. In other words, asbestos, which has been used as a reinforcing fiber, has an excellent reinforcing effect due to its high physical and chemical affinity with cement.
In terms of productivity, the Hachietsu paper machine effectively captures fine particles such as cement, suppresses the escape of these particles from the wire mesh, and at the same time effectively allows only moisture to escape from the wire mesh. It also has the characteristics of However, of these two properties of asbestos, conventional research focused only on the former and did not place much importance on the latter. This is the biggest reason. In other words, in the past, the first step was to select an asbestos alternative fiber that could make the product's physical properties equivalent to those of asbestos cement boards without using asbestos at all, and then find the paper-forming conditions that would allow production. There were many patterns in which research was conducted in these steps. As a result, there was a large difference in performance between non-asbestos cement boards obtained on a laboratory scale and non-asbestos boards obtained on a production scale. For example, as seen in some non-asbestos cement boards currently on the market, their strength is only about 70 to 80% of that of asbestos cement boards.
This is because when paper is made with a formulation that does not contain asbestos, the pulp and reinforcing fibers used cannot sufficiently capture cement particles in water, so cement particles and other fillers often flow out from the wire mesh. This is because the cured product will have a composition completely different from the initially set composition, and production will rely solely on equipment control without taking into account the conditions of the slurry. [Purpose of the invention] This invention provides the ability to
The purpose of the present invention is to provide a manufacturing method for fiber-reinforced cement products that can efficiently produce fiber-reinforced cement products that have physical properties at or above the same level as conventional asbestos cement boards and other asbestos cement products without using asbestos. . [Disclosure of the Invention] In order to achieve the above-mentioned objects, the present invention provides pulp fibers of 1 to 5% by weight, organic synthetic fibers of 0.5 to 2.0% by weight, and/or 0.5 inorganic fibers other than asbestos
~ 10% by weight, and a slurry with a solid content concentration of 3.0 to 13.0% by weight containing hydraulic cement, using a Hachietsu paper making machine to make a paper product, and use this paper product to manufacture a fiber reinforced cement product.
The gist of the present invention is a method for manufacturing a fiber-reinforced cement product, which is characterized in that the slurry used in making the slurry in a sieve cylinder satisfies the following two conditions at the same time. A Slurry filtration coefficient (filtration coefficient per unit area) K (cm ⁴ /sec) is 0.5≦K≦5.0 B Filtrate solid content concentration C at the time of measurement of the filtration coefficient
(% by weight) is C≦0.5 or less.The present invention will be described in detail below. Here, the slurry filtration coefficient K is the following value. First, 0.5 to 1 part of the slurry is poured into a container equipped with a wire mesh with the same mesh size as the wire mesh of the sieve cylinder of the Hachietsu paper machine actually used in production (usually 48 to 65 mesh), and immediately the filtrate volume is Measure V (cm ³ ) and filtration time θ (sec) until V reaches 100 cm ² . Next, (dθ/dV) is calculated from the filtration curve V(θ) obtained from the measured values, and (dθ/dV) is taken as the vertical axis and V is taken as the horizontal axis of the graph. At this time, the following (a) straight line dθ/dV=2/K'(V+α)...The average value of the ^slope (2/
Let K be the value obtained by dividing K′ calculated from K′) by the effective area S (cm ² ) of the wire mesh. Further, C is the solid content concentration of the filtrate obtained at this time. The filtrate (white water) concentration when actually using the Hachietsu papermaking machine is different from the value of the filtrate solids concentration C when measuring the filtration coefficient.
Although the property varies depending on the size of the machine as well as the opening of the sheave cylinder, it has been found by the inventors' experience that the value is about 5 to 10 times as large as C. Examples of using pulp fibers and synthetic fibers as asbestos substitute fibers have already been described in JP-A-55-121918, JP-A-56-37268, and JP-A-56-114857. The inventors have been conducting repeated studies in the past, believing that the use of such fibers is the most common and has a high possibility of producing cement products with high performance. However, it has been confirmed that by simply combining materials already known as reinforcing materials for cement, it is possible to create products with performance relatively similar to current asbestos cement products at the laboratory level, but it is difficult to produce products on actual production lines where production speeds are high. When mixing the raw materials, the mixture could not be the same as the one prepared, and the cement content was low and the fiber content was high.
In other words, the resulting cured product was far from having fibers uniformly dispersed in the binder, which is the basis of reinforcement theory. Therefore, the inventors measured the filtration coefficient K at a slurry concentration of 8% and the filtrate solid content concentration C at the same time for the conventional compounding system used in asbestos cement products. As shown in the figure, it was confirmed that both K and C increased as the amount of asbestos decreased. This suggests that even in the case of a system that does not contain asbestos, if the K and C of the slurry can be made as low as in the case of paper making of conventional slurry for manufacturing asbestos cement products, favorable results may be obtained. Got a guess. Therefore,
Based on solid content, pulp is 1 to 5% by weight, pinylon is 1% by weight as reinforcing fiber, and the rest is Portland cement (assuming pulp is x weight% (99-
x) weight %], and K and C were measured for a slurry with a concentration of 10%. However, as shown in Figures 3 and 4, which show the measurement results, with this blending system, it is extremely difficult to lower the K and C of the non-asbestos slurry to the same level as the K and C of the asbestos cement slurry. It turns out that it is. In FIGS. 3 and 4, ○ indicates a slurry using unbleached softwood kraft pulp [NUKP (CSF700c.c.)] as the pulp, and Δ indicates a slurry using waste newspaper as the pulp. As can be seen in Figures 3 and 4, in order to make the physical properties of non-asbestos cement products as similar as possible to those of conventional asbestos cement products, it is necessary to increase the amount of pulp and reinforcing fibers. This means that it is preferable. but,
Even non-asbestos cement products must be made of noncombustible materials, so combustible pulp and synthetic fibers cannot be used indefinitely. Therefore, a base material test, which is conducted as one of the noncombustible material tests in Japan, was conducted on various non-asbestos cement products (plates) with different total amounts of pulp and synthetic fibers. Figure 5 shows the relationship between the blending amounts of pulp and synthetic fibers and the temperature rise in the furnace according to the base material test. If the temperature rise in the furnace exceeds 50℃, it will be rejected, and if it is below 50℃, it will be passed.As shown in Figure 5, the total amount of pulp and synthetic fibers will not exceed approximately 60% by weight. It turns out that it has to be within the range. Furthermore, considering the price of asbestos substitute materials used in non-asbestos systems, a major challenge in making non-asbestos systems is how to achieve the maximum reinforcing effect using as little reinforcing fiber as possible. Considering the above points, the inventors have determined that pulp fibers are 1 to 5 weight %, organic synthetic fibers are 0.5 to 2.0 weight %, and/or inorganic fibers are 0.5 to 2.0 weight % based on the total solid weight. Regarding a non-asbestos slurry containing 10% by weight and hydraulic cement, we decided to solve the above problem from a different perspective. In other words, we abandon the concept of completely matching K and C with those of asbestos-containing products, and instead
They decided to solve the problem by setting preferable K and C values, by examining the relationship between and strength and by taking into consideration other aspects. Therefore, the following experiments were conducted using various kinds of slurries having the above-mentioned compositions. First, a slurry as shown in Table 1 was prepared by using Portland cement as a hydraulic cement and adjusting the solid content concentration to about 7 to 9% by weight.

【table】

Claims (1)

[Claims] 1. Pulp fibers are 1% by weight based on the total solid weight.
~5% by weight, 0.5~2.0% by weight of organic synthetic fibers and/or 0.5~2.0% of inorganic fibers other than asbestos
A paper product is made from a slurry with a solid content concentration of 10% by weight and 3.0 to 13.0% by weight, including hydraulic cement, using a Hachietsu paper making machine. A method for manufacturing a fiber-reinforced cement product, characterized in that the slurry used for making the slurry satisfies the following two conditions at the same time. A Slurry filtration coefficient (filtration coefficient per unit area) K (cm ⁴ /sec) is 0.5≦K≦5.0 B Filtrate solid content concentration C at the time of measurement of the filtration coefficient
(% by weight) is C≦0.5 2. The method for producing a fiber-reinforced cement product according to claim 1, wherein the organic synthetic fiber is a polyvinyl alcohol synthetic fiber having a fineness of 0.5 to 10 deniers and a fiber length of 12 mm or less. 3. The method for producing a fiber-reinforced cement product according to claim 1, wherein the organic synthetic fiber is an acrylic fiber with a fineness of 0.5 to 20 deniers and a fiber length of 15 mm or less. 4 The inorganic fibers have an average diameter of 5 to 30 μm and a fiber length of
A method for producing a fiber-reinforced cement product according to claim 1, wherein the fiber-reinforced cement product is made of pitch-based carbon fiber of 15 mm or less. 5. The method for producing a fiber-reinforced cement product according to any one of claims 1 to 4, wherein the fiber-reinforced cement product is a plate.