JPS59232805A - Manufacture of fiber reinforced cement board - Google Patents

Abstract

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

Description

[Detailed Description of the Invention] [Technical Field] The present invention is directed to the production of fiber-reinforced cement products that do not contain asbestos at all, by using the Honeynic papermaking machine that has been widely used in the past to produce asbestos cement products. Regarding the manufacturing method.

[Background technology]

Traditionally, hydraulic cement l- has been used as a binding material, and asbestos has been used as a binding material. Inorganic cured materials have been widely used as di-reinforcing materials.

However, in recent years, asbestos has come to be suspected as a carcinogenic substance, and inorganic hardened materials that do not contain asbestos are being considered in various countries, and some of these have already been commercialized.

Because asbestos cement boards have an extremely large number of uses, research into non-asbestos cement boards was carried out from an early stage.However, because asbestos has such excellent advantages, it has the same quality, productivity, and productivity as conventional asbestos cement boards. It can be said that there has not yet been a single non-asbestos cement board available in the world that has all the costs.

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 because it has a high physical and chemical affinity with cement, and it also effectively removes fine particles such as cement during honeycomb papermaking. It has the characteristics in terms of productivity that it is extremely effective in trapping and suppressing the escape of these particulates from the wire mesh, and at the same time, effectively allowing only moisture to escape from the wire mesh. However, in the past, of these two properties of asbestos, people 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 this step. Therefore, there was a large difference in performance between non-asbestos cement boards obtained on a laboratory scale and non-asbestos cement 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 70-80% 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 that is completely different from the initially set formulation, and production will rely solely on equipment control without taking into account the conditions of the slurry.

[Purpose of the Invention] The present invention is to efficiently produce fiber-reinforced cement products that have physical properties on the same level or higher as conventional asbestos cement boards and other asbestos cement products without using asbestos, using a conventional Hachinik papermaking machine. The purpose of this paper is to provide a method for manufacturing a single product of fiber-reinforced cement.

[Disclosure of the Invention] In order to achieve the above-mentioned objects, the present invention provides pulp fibers in an amount of 1 to 5% by weight based on the total solid weight, organic synthetic fibers in an amount of 0.5 to 2.0% by weight, and/or A paper product is made from a slurry containing 0.5 to 10% by weight of inorganic fibers other than asbestos and a solid content concentration of 3.0 to 13.0% by weight, including hydraulic cement, using a Hachinic papermaking machine. The gist of this method is to produce a fiber-reinforced cement product using slurry A, characterized in that the slurry, when prepared using a sieve cylinder, satisfies the following two conditions at the same time. Filtration coefficient (filtration coefficient per area of R position) K (cm
' /sec >0.5≦≦5. OB Filtrate solid content concentration C (weight %) at the time of measurement of the filtration coefficient is C50.5 The present invention will be described in detail below.

Here, the slurry filtration coefficient has the following value. First, the opening is the same as the wire mesh of the sheave cylinder of the Hachinik papermaking machine that is actually used in production (usually 48 to 65 mm).
Pour the slurry into a container equipped with a wire mesh.
．． 5 to 11, and immediately measure the filtrate volume V (c♂) and filtration time θ (sec) until V reaches 100-.

Next, from the filtration curve V(θ) obtained from the measured values, (d
θ/dV) is calculated, and (dθ/dV) is taken as the vertical axis and ■ is taken as the horizontal axis of the graph. Let K be the value obtained by dividing 2' by the effective area S (self) of the wire mesh, which is calculated from the average value (2/2') of the slope in the range of V≦50c+( of the (al line) obtained at this time. .In addition, C is the solid content concentration of the filtrate obtained at this time.The filtrate (white water) a degree when actually using the Hachinik papermaking machine is the value of the filtrate solid content concentration C at the time of measuring the filtration coefficient. The inventors' experience has shown that the value of C is about 5 to 10 times as large as C, although its properties vary depending on the size of the machine as well as the opening of the sheave cylinder.

Examples of using pulp fibers and synthetic fibers as substitute materials for asbestos have already been described in JP-A-55-121918, JP-A-56-37268, and JP-A-56-114857. The inventors have been conducting repeated investigations since the use of such fibers is the most common, and they believe that there is a high possibility of obtaining a cement W product with high performance.

However, it has been confirmed at the laboratory level that it is possible to produce products that are relatively similar in performance to the current Ashest cement products by combining well-known cement as a reinforcing material for cement, but the production speed is limited. On a large actual production line, it is not possible to produce a mixture that is exactly as prepared when the raw materials are first mixed, and the product has a low cement content and a high fiber content, but the fibers are uniformly dispersed in the binder, which is the basis of reinforcement theory. Only a hardened product was produced which was far from that.

Therefore, the inventors measured the filtration coefficient at a slurry concentration of 8% and the filtrate solids 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. From this, even in the case of a system that does not contain asbestos, it is possible to obtain favorable results if the K and C of the slurry can be made as low as the conventional slurry for manufacturing asbestos cement I products. I got a guess that. Therefore, based on the solid content, the valve should be 1 to 5% by weight. ! 1 vinylon as i-strong fiber
K and C were measured for a slurry with a concentration of 10%, with the remainder being Portland cement [(99-X) weight% when the pulp is X weight%]. However, as shown in Figures 3 and 4, the measurement results were disappointing, and with this blending system, it was impossible 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. proved to be extremely difficult. In Figures 3 and 4, O indicates a needle-leaved exposed craft valve [NUKP ((1: SF 700
cc))), △ is a slurry using waste newspaper as a valve.

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 valves and reinforcing fibers. This means that it is preferable. However, even non-asbestos cement products must be non-combustible, 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 amount of valves and synthetic fibers mixed and the temperature rise in the furnace according to the base material test. If the temperature rise in the furnace exceeds 50°C, it is rejected, and if it is below 506°C, it is passed, and as shown in Figure 5, the total amount of pulp and synthetic fibers does not exceed approximately 6% by weight. It turns out it has to be a range. Also, considering the price of asbestos substitute materials used in non-asbestos systems, the major challenge in making asbestos-free systems is how to achieve the maximum reinforcing effect using as little reinforcing fiber as possible. .

Taking the above points into consideration, the inventors have determined that the content of pulpy fibers is 1 to 5% by weight based on the total solid content, and the amount of organic synthetic fibers is 0.5 to 2.0% by weight based on the total solid content.
0.5-10% by weight and/or inorganic fibers
We decided to try to solve the above-mentioned problem from another aspect regarding Tunashest-based slurry containing hydraulic cement. In other words, we should abandon the idea of completely matching K and C with those of the products used by Ashesto, examine the relationship between K and C and strength, or consider other aspects, and set the value and C to a preferable value. We decided to solve this problem by setting a value. Therefore, the following experiments were conducted using various kinds of slurries having the above-mentioned configurations. First, a slurry as shown in Table 1 was prepared by using Pol] land cement as a hydraulic cement and adjusting the solid content concentration to about 7 to 9% by weight.

(Left below) In the table, NUKP refers to kraft pulp exposed to needles, vinylon is made by Kuraray Co., Ltd., acrylic is made by Kanebo Co., Ltd., and wollastonite is NY produced in the United States.
AD-G and polyacrylamide-based flocculants were used, respectively. Using 0.5β of each slurry, we determined the filtration coefficient and the concentration of the filtrate using a freeness test, which has a 50-mesh wire mesh (diameter 50 mm) at the bottom, which has the same opening as the sieve cylinder of the Hachinic papermaking machine owned by the inventors. C was measured in advance, and then each slurry was made into paper using the Hachinic paper making machine under the paper making conditions shown in Table 1. The press-formed green sheet is then first cured at 50 to 60°C for 12 hours in an atmosphere with low moisture evaporation, and then at room temperature (
After secondary curing for 2 weeks at a temperature of approximately 16 to 20°C, a cement board was obtained. After that, take out the sample arbitrarily and
Test pieces were prepared by cutting into 120 mm pieces, dried in a dryer at 60°C for 24 hours, and after adjusting the water content to 5 to 10% by weight, physical properties were measured. The measurement results are shown in Table 1. However, each physical property data is based on test piece 10111i1 (n=10
) is the average value of

Slurry K and C and bending strength of test piece (cured body) (
Fig. 6 shows the relationship with the upper direction). In the figure, the numbers do not represent the experiment numbers. From Figure 6, the inventors have determined that the filtration coefficient and filtrate solids concentration C are similar to the conventional asbestos cement board.
The smaller the value, the greater the bending strength.
In particular, it has been found that when a slurry having a K of 5.0 or less and a C of 0.5 or less is used, the bending strength (in the upward direction) increases significantly. In addition, K and C of the slurry
It was also found that the same can be said from the relationship between the bending strength of the test piece and the bending strength (in the bending direction).

Needless to say, a large value of K indicates that the slurry has good freeness, and if slurry with the same composition has too good freeness, the sieve should be removed at the time of the sieve cylinder. When there is a difference in liquid level between the inside and outside of the cylinder, the productivity will drop to a minimum of α11,1.

As in the past, if the slurry contained about 10 to 15% by weight of asbestos, it had appropriate freeness. If the slurry is completely asbestos-free,
As the ability to capture fine particles such as cement 1 is reduced, cement and other particles escape from the sieve surface to the white water side.
The K value often increases. On the other hand, even if the K value itself is about the same, if the water that passes through the sieve, that is, white water, is mostly water, most of the cement particles will remain in the cake, and a green sheet with the initial composition will be formed. However, on the other hand, if a large amount of solids passes through the sieve together with water, the cement content will decrease, resulting in a green sheet with a reduced amount of binder and a blend with an excessive amount of fiber.

Therefore, it can be deduced from the above that it is desirable that the values of K and C are appropriately small.

The inventors thought that the smaller the value of K, the better, and conducted various studies. However, when K is less than 0.5, the freeness deteriorates significantly. Even if a sheet 1-) is formed, the dehydration properties are insufficient, and when the paper product is wound around a making roll a predetermined number of times, it becomes sticky and the shape of both sides is distorted, and when the rolled material is cut out from the making roll, it comes off. It was confirmed that there is a tendency for things to not go smoothly.

Therefore, it is most preferable that K be 0.5≦ and ≦5.0.

After the above studies, the inventors determined that the amount of bulbous fiber was 1 to 5% by weight based on the total solid content, and the amount of organic synthetic fiber was 0.5% by weight based on the total solid content.
~2.0% by weight and/or 0.5 to 10% by weight of inorganic fibers other than asbestos, and hydraulic cement, with a solid content concentration of 3.0 to 13% by weight, K of 0.5
If we use a slurry with a C of 0.5 or less and a C of 0.5 or less, it is possible to efficiently produce fiber-reinforced cement products that have the same physical properties as conventional asbestos cement boards and better than Hell without using asbestos. With this in mind, he completed this invention.

Methods for preparing slurry that meet the K and C conditions mentioned above include, for example, a beater, a disc refiner, or a double disc refiner, which has become particularly widely used in the paper industry in recent years. There is a way to increase the freeness of the valve you use. According to this method, even if the composition is kept constant, it is possible to set the above conditions by changing K and C.

Another method is to satisfy the conditions K and C by recycling bulbs with short fiber lengths, such as waste newspapers and waste kraft paper.

If the pulp is not particularly processed, K and C can be added to the slurry as inorganic fillers with fine particle size or swelling properties such as montmorillonite.
conditions can be easily met. Specifically, in addition to clay minerals such as seviolite, hentonite, acpalgide, kaolinite, halloysite, and sericite, we also include silica materials with an average particle size of 1 μm or less (silicon dust, colloidal silica, etc.). etc.), precipitated calcium carbonate, barium sulfate, etc. are used.

When the pulp is not particularly treated and no inorganic filler is used, K can be decreased by increasing the slurry concentration, and conversely, K can be increased by decreasing it. On the other hand, in order to lower C, it is recommended to add a large amount of polymer flocculant to the slurry. However, if too much polymer flocculant is added, K may increase and disadvantages may occur, so care must be taken.

When using organic synthetic fibers, use polyvinyl alcohol synthetic fibers with a fineness of 0.5 to 10 deniers and a fiber length of 12n+n+ or less, or acrylic fibers with a fineness of 0.5 to 20 deniers and a fiber length of 15 mm or less, When using inorganic fibers, the average diameter is 5 to 30 μm and the fiber length is 1
It is preferable to use pitch-based carbon fibers of 5n+m or less. This is because it has the effect of improving the performance of the resulting fiber-reinforced cement product.

The method for producing fiber-reinforced cement products from slurry is the same as conventional methods. That is, a slurry is made into paper using a Hachinic paper making machine, and the obtained paper product (uncured board) is dehydrated under pressure using a press at an actual pressure of about 50 to 300 kg/cJ. Next, the product is cured and cured to obtain a plate-shaped or other fiber-reinforced cement I-product.

〔Effect of the invention〕

In the manufacturing method of the fiber-reinforced cement product according to the present invention, since the slurry as described above is used, asbestos is not used (although fiber-reinforced cement 1, which has the same physical properties as asbestos cement products and better than that of the asbestos cement product), does not use asbestos. I can train well.

[Brief explanation of drawings]

Figure 1 is a graph showing the relationship between the amount of asbestos blended in a slurry containing asbestos and the filtration coefficient, Figure 2 is a graph showing the relationship between the amount of asbestos blended in the same slurry and the filtrate solid content concentration C, and Figure 3 The figure is a graph showing the relationship between the amount of pulp and the filtration coefficient in a slurry containing pulp and vinylon fibers. Figure 4 is a graph showing the relationship between the amount of pulp and the filtrate solids concentration C in the same slurry. Figure 6 is a graph showing the relationship between the content of pulp and synthetic fibers and the temperature rise in the furnace, and Figure 6 is a graph showing the relationship between the slurry filtration coefficient, filtrate solids concentration C, and bending strength (in the upward direction). People Patent Attorney Takehiko Matsumoto C type, 4 mountains 0)

Claims (5)

[Claims] (1) 1 to 5% by weight of bulbous fiber based on the total solid weight;
0.5 to 2.0% by weight of organic synthetic fibers and/or 0.5 to 10% by weight of inorganic fibers other than ashest, and solid content concentration of 3.0 to 13.0 f including hydraulic cement.
% fit% slurry using a Hachinic paper-making machine, and when manufacturing a fiber-reinforced cement product using this paper product, the slurry when made with a sheep cylinder satisfies the following two conditions at the same time. A method for manufacturing a fiber-reinforced cement product characterized by: A Slurry filtration coefficient (filtration coefficient per unit area) K
(cm'/sec) is 0.5≦≦0.5B The filtrate solids concentration C (weight %) at the time of measuring the filtration coefficient is C
60,5 (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 or less. (3) The method for manufacturing a fiber-reinforced cemeshite product according to claim 1, wherein the organic synthetic fiber is an acrylic fiber having a fineness of 0.5 to 20 deniers and a tA fiber length of 15 a+m or less. (4) Inorganic fibers have an average diameter of 5 to 30 μm and a fiber length of 1
A method for manufacturing a fiber-reinforced cement product according to claim 1, wherein the fiber-reinforced cement product is made of pitch-based carbon fiber of 5 o+m 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.