JPH0225856B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field] The present invention relates to a method for producing an inorganic cured body used as a building material. More specifically, the present invention relates to a method for producing an inorganic hardened material such as a cement-based inorganic building material without using asbestos. [Background Art] Inorganic hardened bodies containing cement as a binder and asbestos as a reinforcing material have been widely used. This is because when asbestos is used as the reinforcing fiber, the reinforcing effect on the inorganic hardened material becomes remarkable, and the inorganic hardened material can be produced by a papermaking method suitable for mass production such as the Hatchiek papermaking method. In this method, a slurry containing raw materials is made into paper using a paper making machine such as a Hachietsu paper making machine, and the obtained excipient is cured to produce an inorganic hardened material. At that time, papermaking becomes possible if asbestos is used in an amount of 5% by weight or more based on the solid content of the raw material. However, the use of asbestos poses a risk of causing asbestos pollution, and continuing to use asbestos in the future poses a problem in terms of protecting the social environment. Therefore, in recent years, research has been actively conducted on inorganic hardened materials that do not contain asbestos. As an example,
There is an inorganic hardened material that contains pulp instead of asbestos, and such products are already on the market. However, this inorganic cured product had the following drawbacks and was unsuitable for use as a general building material. That is, it has the disadvantage that it is not nonflammable. In order to make this inorganic hardened material using the papermaking method, it is necessary to use pulp with a content of approximately 6% by weight or more based on the solid content of the raw materials (hereinafter, all expressions are based on the solid content of the raw materials). If a large amount of pulp is used, the resulting inorganic cured product will no longer be nonflammable. In addition, it has the disadvantage of insufficient strength, especially when water is absorbed, and is therefore unsuitable for use as an exterior building material. Currently, in addition to pulp, various alternative fibers for asbestos are being considered, including inorganic fibers such as glass fiber, carbon fiber, steel fiber, and wollastonite, and organic fibers such as vinylon, acrylic, and polyethylene.
In both cases, the thickness of each fiber is thicker than that of asbestos.
Unlike asbestos, it does not mix well with cement, so it has not been used alone. [Object of the invention] In view of the above-mentioned circumstances, the present invention aims to provide a method for producing an inorganic hardened material that is nonflammable, has high strength, and can be mass-produced by a papermaking method without using asbestos. purpose. [Disclosure of the Invention] As a result of repeated research, the inventors have found that by successfully using pulp that is beaten and fibrillated without being cut into short pieces, and virgin pulp that is simply disintegrated without being fibrillated, a non-flammable and strong material has been developed. We discovered that it is possible to mass-produce cured products with high viscosity using the papermaking method, and hereby completed this invention. In other words, by properly setting the beating conditions of virgin pulp made of softwood, hardwood, etc., using a PFI mill, single-day cliff reiner, double-day cliff reiner, etc., fiber length of 590 microns or more (28 mesh) can be reduced to 60% by weight. Fibrillation is performed while maintaining the freeness of Schottsper.
1 to 5% by weight of pulp with 40°SR or more and 95°SR or less based on the total solid content, Schopper freeness
If simply disintegrated virgin pulp of 40°SR or less is blended at a ratio of 0.5 to 1.0% by weight based on the total solid content, Hatchech can be obtained even if the amount of pulp in the slurry solid content is 6% by weight or less. It is possible to make paper by this method, and the effect of virgin pulp also improves water drainage in each process of suction, making roll, and press, so it is nonflammable and has a specific gravity, which is the objective of this invention. They discovered that it was possible to obtain a high-strength board with a high level of strength, and thus completed this invention. Therefore, the present invention provides a method for obtaining an inorganic hardened body obtained by curing a shaped body obtained by a papermaking method from a slurry containing cement.
Pulp with 60% by weight or more of 590 microns or more and a Schottspur freeness adjusted to 40°SR or more and 95°SR or less by fibrillation is used at a ratio of 1 to 5% by weight based on the total solid content and a Schottspur freeness of 40°SR or more and 95°SR or less. Pulp that is not beaten under 40゜SR is 0.5 to total solids.
They each contain 1.0% by weight, and if necessary, fillers and reinforcing fibers are added to this to increase the concentration to 4.
The gist thereof is a method for producing an inorganic cured body characterized by using a slurry having a filtration coefficient of 15% by weight or less and a filtration coefficient of 5 cm ⁴ /sec or less. Here, the filtration coefficient is defined as follows.
That is, first, a slurry 0.5 to 1 thick adjusted with the above-mentioned composition is placed in a wire mesh with the same mesh size as the sheave cylinder wire mesh of the Hachietsu paper machine actually used in production (usually 48 to 65 mesh). Immediately measure the filtrate volume V (cm ³ ) and filtration time θ (seconds) until V reaches 100 cm ³ . Calculating (dθ/dV) from the obtained filtration curve V(θ), and plotting (dθ/dV) on the vertical axis and V on the horizontal axis of the graph, it is expressed by the following formula (a). Find the average value (2/K') of the slope of the approximate straight line dθ/dV=2/K' (V+α) (a) up to 50 cm ³ .
K′ calculated from this average value is the effective area S of the wire mesh
The value divided by (cm ² ) is defined as the filtration coefficient K. This invention will be explained in detail below. The cement used as a binding material here is:
It is not particularly limited as long as it is hydraulic. For example, Portland cement, blast furnace cement, etc. As the pulp, it is preferable to use softwood or broadleaf wood pulp or ungrained kraft pulp. If waste paper such as sulfite paper or kraft paper is produced in large quantities, it may cause poor curing of cement due to the impurities it contains. However, since waste paper generally has short fiber length, its shovel freeness is relatively high. Therefore, it is often used in small quantities in combination with asbestos, etc., and in this invention, when used in combination with the aforementioned pulp fibrillated to 40°SR or more and 95°SR or less, fibers with a fiber length of 590 microns or more are % (hereinafter abbreviated as %) or more, and the freeness can be used within the range of 40°SR or more and 95°SR or less. In this invention, the shovel freeness is 40°SR or more.
60 fibers with a length of 95°SR or less and a length of 590 microns or more
% or more of softwood and/or hardwood pulp is used in an amount of 1 to 5% of the total solid content;
Disintegrated needlewood and/or hardwood pulp of 40° SR or less is used in an amount of 0.5 to 1.0% of the total solid content. That is, if the amount of fibrillated pulp is less than 1%, even if other fine fillers that impair filtration performance are used in combination, the filtration coefficient cannot be lowered to a level that allows paper-making using the hatchet method. Even if it were possible, a large amount of cement particles would escape from the mesh of the cylinder together with water, which would not only result in lower product quality than expected, but would also cause problems such as pulp clogging during the production process, which is undesirable. In addition, if the amount of fibrillated pulp exceeds 5%, it is of course possible to make paper, but considering the preferable addition amount when adding other organic reinforcing fibers, it is difficult to achieve nonflammability. It will fail. On the other hand, if the virgin pulp of 40° SR or less is less than 0.5%, even if the paper can be made during paper making, the dehydration properties will be poor in the subsequent process, that is, the process of dewatering the cake through felt, and the making roll will fail. When the cake is rolled up, there is a high risk that the cake will stick to the roll surface or lose its shape because the moisture content is too high. On the other hand, if it is used in excess of 1%, the filtration coefficient increases, the filtrate solids concentration increases, and the yield of cement decreases dramatically. Since the expansion (spring back) upon opening increases, only an inorganic cured product with a low specific gravity can be obtained. When producing an asbestos-free fiber-reinforced inorganic hardened material using a paper-making method such as the Hachietsu method, as mentioned above, the fibrillated pulp is
%, but if only fibrillated pulp is used, even if the papermaking itself can be made, the dehydration of the cake will be poor on the felt, on the making roll, or during pressing.
An inorganic cured product having sufficient specific gravity cannot be obtained. On the other hand, in the manufacturing method according to the present invention, 0.5 to 1% of virgin pulp is used in combination, so dehydration from the cake is performed more efficiently during manufacturing than when only fibrillated pulp is used, so pulp fibers and cement This results in an inorganic cured product with a high specific gravity and a uniform hardness. The virgin pulp used in the method of this invention is
It is usually disintegrated softwood pulp and/or hardwood pulp with a shovel freeness of 40°SR or less, but it is not possible to make paper from this virgin pulp alone, even if other fillers are used in combination. This is true even if amounts exceeding the range of 0.5 to 1% are used. This is because the filterability of the slurry is so good that cement particles escape into the filtrate, and there is no difference in liquid level between the inside and outside of the sheave cylinder when using a Hatchiek papermaking machine. Therefore, by using this virgin pulp in combination with a highly beaten pulp with a shovel freeness of 40 to 95°SR, it was possible to produce an inorganic hardened material with a high specific gravity with a sufficient matrix by the papermaking method. This allows for more efficient production. Next, regarding the fiber length of the fibrillated pulp, it is beaten using a beating machine such as a PFI mill, single-disccliff reiner, double-disccliff reiner, etc., and development progresses by cutting the fibers into short lengths at the same time as fibrillation. It is necessary to beat the pulp in order to increase the freeness of the pulp, but if the pulp is beaten too much, the fibers will break into short pieces and the hardened material will no longer function as a reinforcing material. For example, pulp fibers with a length of less than 590 microns exhibit almost no reinforcing effect and are only effective in increasing the shovel freeness, so it is desirable to keep the amount of this fiber as low as possible. Here, the reason why the pulp with a fiber length of 590 microns or more is set to be 60% or more of the total amount of pulp is that if the fiber length is less than this, the water absorption rate of the cured product increases and the strength upon water absorption decreases significantly. Next, a filler is not necessarily necessary, but if it is used, it is recommended to use sepiolite, bentonite, etc., which has a swelling degree of 3 times or more, or crystalline or amorphous silica with an average particle size of 5 microns or less. good. Here, the degree of swelling is defined as below. Swelling degree: Amount of water absorbed after 24 hours/Weight of filler before water absorption By using such a filler in combination with the above-mentioned pulp and mixing it with cement and water, the filtration coefficient of the slurry can be further lowered. It can be made into a slurry that is easy to make. In other words, by using a filler in combination, it is possible to obtain a filtration coefficient that allows papermaking even when using pulp with a low degree of beating, which not only reduces power costs during pulp beating, but also reduces product usage. This provides flexibility in that the composition can be changed not only by pulp but also by filler, depending on the purpose. Further, when crystalline or amorphous silica with a size of 5 microns or less is used as a filler, it reacts with cement components during curing, resulting in a product with even higher strength and higher quality. Although it is not clear why the use of such a filler in combination with the fibrillated pulp described above does not result in poor drainage properties of the slurry and also improves the cement yield, it is speculated that the fine particles of the fibrillated pulp This is thought to be because the filler is well intertwined with the fibers, creating a mesh-like structure for filtration. The amount of filler added is 1 based on the total solid content.
It is best to set it to ~10%. If it exceeds 10%, there is a risk of a decrease in strength. Next, reinforcing fibers other than pulp are not necessarily necessary, but if used, inorganic fibers such as glass fibers, carbon fibers, steel fibers, wollastonite, or polyvinyl alcohol (also referred to as vinylon, hereinafter abbreviated as PVA) are recommended. ), acrylic, polyethylene, and other organic fibers can be used, but PVA is the most preferred organic fiber, and wollastonite is the most preferred inorganic fiber. It is also preferable to use PVA fibers or acrylic fibers whose width or diameter is increased in some places. Two or more types of reinforcing fibers may be used simultaneously. It is known that PVA fibers have the best bonding properties with cement among organic fibers due to their hydrophilic groups, and have excellent reinforcing effects. By using this in combination with fibrillated pulp and virgin pulp, it is possible to further improve the strength, particularly the impact resistance strength. The reason for this is that PVA alone has poor compatibility with cement and easily comes off, but when used in combination with the above pulp, the PVA fibers and fibrillated pulp fine fibers intertwine well, preventing the PVA from slipping. It can be estimated that PVA
As a fiber or acrylic fiber, the thickness is 5 to 50.
It is preferable to use microns and a length of 3 to 10 mm. The content of PVA fiber or acrylic fiber is preferably 0.3 to 2%. This is because within this range, the reinforcing effect is greatest. Even if the amount of PVA or acrylic is increased beyond 2%,
The strength of the cured product hardly increases, and only the compounding cost increases. This is presumed to be because when PVA or acrylic is contained in an amount exceeding 2%, its dispersibility deteriorates. Furthermore, if it is less than 0.3%, the reinforcing role cannot be fulfilled, and the sheet shape retention, especially when uncured, becomes insufficient. Wet spinning method, as PVA or acrylic
A cured product with high strength can be obtained by using fibers spun by a dry spinning method or the like, which are shaped during heat treatment so that the width or diameter of the fibers becomes larger in some places. Figure 1 is a perspective view showing a morphological model of such a fiber;
The figure is a side view of FIG. 1 viewed from the arrow A side, and FIG. 3 is a side view of FIG. 1 viewed from the arrow B side. As shown in these figures, the fiber 1 has portions 2 that are widened at some places in the fiber axis direction. These portions 2 have increased widths as shown in FIG. 2 when viewed from at least one side. In other words, since it is normal for the fibers to have twists in the part 2 where the fibers are pressed and widened by the shaping during heating, the width becomes wider as shown in Figure 2 depending on the viewing angle. See you, 3rd
This is because it looks flat as shown in the figure. However, the diameter is not limited to that shown in this model diagram, and the diameter may be large when viewed from any angle. 4 and 5 show microscopic photographs of the fiber, with FIG. 4 being a side view before molding, and FIG. 5 being a side view after heat treatment molding. As shown in FIG. 5, after the heat treatment molding, portions 2 with large widths or diameters are formed here and there. Fiber diameter of part 2 (t ₁ ) and original fiber diameter (t ₂ )
is in the relationship t ₁ > t ₂ . The portions 2 do not need to be regularly arranged in the fiber axis direction.
The diameter of the portion 2 is preferably about 2 to 3 times the original fiber diameter (t ₂ ), but is not particularly limited to this. Further, the number of portions 2 is preferably 50 fibers long.
For ~2000μ, you only need to own one piece with a length of about 20 to 100μ. This portion functions to improve adhesion at the interface with the cement matrix.
Therefore, the cured product obtained by mixing PVA fibers or acrylic fibers having such parts into a cement matrix has significantly higher strength (bending strength, impact strength, strength, etc.) increases. Although the mechanism of this strength development is still unclear, it is possible to increase the surface area without reducing the cross-sectional area of the fibers, which increases the bonding area with the cement matrix and increases the fiber strength due to the protrusions. It is presumed that this is because it becomes difficult to remove. Since the cross-sectional area does not decrease at all, there is no decrease in the strength of the fiber itself. Large width or diameter parts here and there
The heat treatment for providing PVA fibers or acrylic fibers can be carried out, for example, as shown in FIG. A roll 3 made of metal, etc., and a roll 4 made of metal, etc., which has many minute irregularities on its circumferential surface.
The fiber 5 is passed between the rolls 3 and 4 with the surface temperature of the roll 4 being about 200 to 300°C. In this way, a fiber having a large width or diameter in some places can be obtained. The gap (clearance) between both rolls 3 and 4 needs to be determined according to the thickness and diameter of the fibers used, but if the thickness or diameter is about 16μ, it is preferably about 8μ. Further, the distance between the convex and convex portions of the irregularities provided on the roll 4 needs to be determined depending on the desired distance between the portions having a large width or diameter. It is well known that wollastonite is the most compatible with cement among inorganic fibers and is effective as a reinforcing material. Similar to the aforementioned PVA, this wollastonite can also be used in combination with fibrillated pulp to improve its effectiveness. In other words, wollastonite is entangled around the fine fibers of the fibrillated pulp, improving the yield of cement and, as a result, improving the strength. Furthermore, the use of wollastonite has the effect of suppressing the dimensional change rate, which is a drawback of inorganic cured products mainly using pulp. Wollastonite fiber length, thickness,
Although the shape is not particularly limited, it goes without saying that one with as large an aspect ratio as possible is preferable. The amount of wollastonite used is preferably 2 to 15%. If it is less than 2%, the effect of adding wollastonite becomes small, and if it exceeds 15%, the reinforcing effect itself does not decrease, but the specific gravity of the cured product decreases, so the reinforcing effect as a whole becomes weaker. A slurry is made by mixing the above-mentioned raw materials and water, and the solid content concentration of this slurry needs to be 4 to 15%. Preferably it is 6-10%. If it is less than 4%, the solid content in the slurry will not be transferred to the paper making section (wire mesh) of the paper making machine, resulting in poor productivity, and in addition, the solid content in the slurry will be reduced. tends to precipitate, making it impossible to obtain an inorganic cured product having the intended composition. On the other hand, if it exceeds 15%, the thickness of the cake formed will become uneven, and it will tend to be difficult to obtain a homogeneous cured product. It is necessary to adjust the filtration coefficient of the slurry to 5 cm ⁴ /sec or less, which is an absolute condition for paper making using the hatchet method or the like. In this invention, this 5cm
⁴ /sec can be achieved by adjusting the amounts of pulp and inorganic filler as described above. A slurry is made with the above-mentioned composition, and it is made into paper using a paper making machine such as a Hachietsu paper making machine, and then laminated to form a shaped body of an appropriate thickness. By curing this shaped body, a hardened body can be obtained. Next, examples will be described together with comparative examples. [Example, Comparative Example] Using the raw materials shown in Table 1, Example 1 was prepared using the Hachietsu method using a Hachietsu paper making machine.
-12, inorganic cured bodies of Comparative Examples 1 to 6 were made. Table 1 also shows the manufacturing conditions and the results of testing the obtained cured products. The filtration coefficient of all slurries was 5 cm ⁴ /sec. In the table, in the evaluation of frost damage resistance, ◎ indicates good, ○ indicates fair, and × indicates unsuitable. Also,
NUKP is softwood unbleached kraft pulp.

【table】

【table】

〔Effect of the invention〕

Since the method of the present invention is configured as described above, it is possible to mass-produce a nonflammable and high-strength inorganic cured body by a paper-making method without using asbestos.

[Brief explanation of drawings]

Figure 1 shows PVA whose width has increased in some places.
A perspective view showing a morphological model of fiber or acrylic fiber, Fig. 2 is a side view of Fig. 1 seen from the arrow A side, Fig. 3 is a side view of Fig. 1 seen from the arrow B side, Figs. Figure 5 shows microscopic photographs of PVA fibers or acrylic fibers; Figure 4 is a side view before molding, Figure 5 is a side view after heat treatment molding, and Figure 6 is an explanation of heat treatment. It is a diagram.

Claims (1)

[Claims] 1. In a method for obtaining an inorganic hardened body by curing a shaped body obtained by a paper-making method from a slurry containing cement, in paper-making, a fiber length of 590 μm or more is 60 μm.
1 to 5% by weight of pulp with a Schottspar freeness adjusted to 40° SR or more and 95° SR or less by fibrillation based on the total solid content, and a pulp with a Schottspar freeness of 40° SR or less. Each contains unbeaten pulp at a ratio of 0.5 to 1.0% by weight based on the total solid content, with a concentration of 4 to 15% by weight and a filtration coefficient of 5.
A method for producing an inorganic cured product, characterized by using a slurry adjusted to cm ⁴ /sec or less. 2. The method for producing an inorganic cured product according to claim 1, wherein the pulp is a pulp of a softwood and/or a hardwood or a non-grained pulp.