JPH1177638A - Production of fiber reinforced cement panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily form deeply carved uneven patterns on the surface of a fiber reinforced cement panel produced by a papermaking method by press molding without restricting a material. SOLUTION: In a one-layer flow-on molding method wherein a cement slurry is supplied to a felt belt 5 equipped with a suction dehydrator 4 in a laminar state 6 and sucked and dehydrated to form a panel, a cement slurry A containing 8-20 wt.% of inorg. porous particles having high bulk specific density and easily collapsed by press pressure described hereinafter is supplied to the felt belt 5 or the formed cement layer on the felt belt 5 to form a layer and the whole layer is cut into a dimension fitted to press molding described hereinafter and the cut uncured fiber reinforced cement panel 8 is pressed to impart uneven patterns to the surface of the panel and this panel is aged and cured according to a usual method on and after.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a fiber reinforced cement board, and more particularly to an improvement in a method for producing a fiber reinforced cement board by a flow-on molding method.

[0002]

2. Description of the Related Art A flow-on molding method is known as a method for producing a fiber-reinforced cement board. This flow-on molding method is a kind of papermaking method in a method of producing a fiber-reinforced cement board, in which a cement slurry composed of a fiber-reinforced cement is supplied in a layer form on a felt belt equipped with a suction dewatering device, and a predetermined moisture content is obtained. It is transported and dehydrated until it becomes a plate shape, and then cut at predetermined lengths at the end of the felt belt,
It refers to a process consisting of a step of pressing to form an uneven pattern on the surface and curing and curing.

[0003] This fiber-reinforced cement board is manufactured by another papermaking method, for example, laminating a thin seed film made by a cylindrical round mesh on a making drum, and then cutting and flattening and pressing. This method has the advantage that a thick fiber reinforced cement board can be formed at a time and the production efficiency is good as compared with the round net forming method of forming into a plate shape.

[0004]

By the way, many fiber-reinforced cement boards are provided with an uneven pattern on the surface to impart a design, and the uneven pattern is formed by pressing as described above. However, in the case of the fiber reinforced cement board manufactured by the above-mentioned papermaking method, there is a problem that it is relatively difficult to give a deep uneven pattern clearly.

[0005] That is, when the sheet is made by the papermaking method, the moisture content of the sheet is considerably reduced by suction dehydration. When the surface of such a sheet is pressed, as shown in FIG. As the mold protrusion 1 enters, the protrusion side surface 1A
The plate forming material 2 is drawn in the approach direction as shown by the arrow, and cracks 3 are generated on the periphery of the convex portion.

In the final stage of press compression, FIG.
As shown in FIG. 5, the molding material 2 flows along the press platen surface 1B in the direction of eliminating cracks as indicated by the arrow. However, if the moisture content is small, the fluidity is limited, so that the molding material 2 does not completely disappear. Although the cracks 3 formed in the initial stage become lighter to the extent, there is a problem that they remain on the product surface as they are.

[0007] However, it is known that such a problem can be solved by increasing the fluidity of the surface of the uncured plate during pressing. For this reason, in the case of the flow-on production method, the amount of suction and dewatering is adjusted in the process of pouring and transferring the slurry onto a felt belt, the moisture content is increased to a level at which the slurry can be produced, and the surface of the molded plate is directly subjected to uneven pressing. It was customary to provide a deeply carved uneven pattern.

However, when the water content is large as described above, there is a problem that the size of the shaping angle for deep carving is limited due to the fluidity remaining in the slurry after pressing.
Furthermore, depending on the press pressure speed when the water content is high,
Water running occurs in the structure and surface of the uncured cement board at the time of pressurization, and the inorganic particles contained in the structure flow out with the water running, which causes cracks on the product surface and roughening of the surface There has been a problem that the design is reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the present invention to easily produce a deeply carved uneven pattern on the surface of a fiber reinforced cement board manufactured by papermaking without limitation of materials. It was made for the purpose of.

[0010]

According to the first aspect of the present invention, there is provided a one-layer flow-on molding method in which a cement slurry is supplied in a layer form on a felt belt provided with a suction dewatering device, and the plate is formed by suction dehydration. After supplying a cement slurry containing 8 to 20% by weight of inorganic porous particles which are easily crushed by a pressing pressure described later on the felt belt and stratified,
It is characterized in that it is cut into a size suitable for press molding described below, the cut uncured fiber-reinforced cement board is pressed to give an uneven pattern on the surface, and then cured and cured according to a conventional method.

That is, a layer is formed by a cement slurry containing 8 to 20% by weight of inorganic porous particles which are easily crushed by pressing pressure, and a void is interposed between the raw material particles by crushing the inorganic porous particles at the time of pressing. Decrease viscosity between particles.

Thus, a deeply carved concave and convex pattern is expressed while preventing the occurrence of cracks. At this time, since the water in the slurry is absorbed by the crushed inorganic porous particles, even if the water in the layer is slightly excessive, the fluidity of the cement slurry is suppressed by a substantial decrease in the water content after pressing even if the water in the layer is slightly excessive. As a result, the shape of the concavo-convex pattern is maintained, and more specifically, the shape after pressing is reliably maintained even at a deep shaping angle.

There are no special characteristics in the material of the cement compound other than the above-mentioned inorganic porous particles and the compounding ratio itself, and the same material and compound as in the prior art are used. In the above, as the inorganic porous particles that are easily crushed, for example, the specific gravity is 0.11 to 0.17
The specific gravity is 0.055, which is very light compared to the normal pearlite,
As shown in FIG.
Under pressure of 5% and ordinary pearlite under pressure of 1.96 to 7.84 MPa, inorganic porous particles such as low specific gravity pearlite having a very low volume residual ratio compared to a volume residual ratio of 78 to 62% are used.

The amount of the inorganic porous particles to be added is set to 8 to 20% by weight. If the amount is less than 8% by weight, the amount of the inorganic porous particles which are crushed during pressing is small, and sufficient voids are formed between the raw material particles. It is difficult to form a deep uneven pattern without causing cracks, and when the amount is more than 20% by weight, the cement mixing amount in the slurry is reduced by that amount, and the cement bonding strength is not sufficient. is there.

According to a second aspect of the present invention, a cement slurry is supplied in a layer form on a felt belt provided with a suction dewatering device.
In the single-layer flow-on molding method in which the board is made by suction dehydration,
In the process of supplying a cement slurry composed of a conventional method in a layer on the felt belt, and carrying out suction dehydration and transport, the inorganic porous particles having a high bulk specific gravity and easily crushed by a pressing pressure described below are used as the base layer. After the cement slurry containing 8 to 20% by weight is further supplied in a layered form and laminated, it is cut into a size suitable for press molding described below, and the cut uncured fiber reinforced cement board is pressed from the upper layer to form irregularities on the upper layer surface. It has a pattern and is cured and cured according to a conventional method.

That is, the base layer is a layer composed of a normal cement compound, and only the surface layer is formed by a cement slurry containing 8 to 12% by weight of inorganic porous particles which are easily crushed by pressing pressure at the time of pressing. By crushing the porous particles, a deeply carved uneven pattern is expressed.

There is no particular limitation on the material of the cement slurry of the base layer. Thus, normal cement formulations with or without inorganic porous particles can be used.

It is desirable to use pulp fibers having a long fiber length as the reinforcing fibers added to the cement composition of the base layer. This is because the strength of the entire plate material is maintained by this base layer.

In the above, the inorganic porous particles which are easily crushed include low specific gravity pearlite as described above.
Further, the addition amount of the inorganic porous particles is set to 8 to 20% by weight for the same reason as in claim 1.

According to a third aspect of the present invention, in the method for producing a fiber reinforced cement board according to the second aspect, the slurry concentration of the upper layer cement slurry is 15 to 40%.

The reason why the slurry concentration of the upper layer cement slurry is set to 15 to 40% is that the upper layer slurry is a layer having a high fluidity and combined with a large amount of added inorganic porous particles, a layer suitable for deep engraving press. To do that. If the slurry concentration is less than 15%, the solid content is too small, and the material flows at the time of pressing, which makes it difficult to form a concavo-convex pattern. If the slurry concentration is more than 40%, the solid content increases, resulting in poor fluidity. Worsened and the pump supply becomes difficult,
This is because stratification itself becomes difficult.

The invention of claim 4 is the invention of claim 2 or claim 3.
In the method for producing a fiber-reinforced cement board, the reinforcing fiber added to the cement slurry of the upper layer is a cellulosic fiber having a short fiber length.

Cellulose powder as the reinforcing fiber in the upper layer has a very short fiber length, so that the fluidity of the cement slurry in the upper layer due to the addition thereof is small, and the formation of a deeply carved uneven pattern becomes clearer. In addition, the addition of cellulose powder makes it possible to reinforce the upper layer.

As the cellulosic fiber having a short fiber length,
Softwood pulp, hardwood pulp with a short fiber length, cellulose powder, etc., having a high degree of beating and a CSF of 400 ml or less are used.

[0025]

Next, an embodiment of the present invention will be described. As a cement compound, for example, cement 40% by weight, silica sand 40% by weight, perlite 10% by weight, pulp fiber 10% by weight
In a basic composition generally used such as the above, a low specific gravity pearlite having a volume remaining ratio of 0.055 and a specific gravity of 0.055 as shown in FIG.

[Example 1] The amount of low specific gravity pearlite added in the composition of the above example was adjusted to 1% by weight to 15% by weight. Was prepared.

In addition, in the above-mentioned composition, the increase and decrease of other compounding raw materials accompanying the increase and decrease of the addition amount of low specific gravity pearlite were adjusted by increasing and decreasing both the addition amounts of cement and silica sand by proportional calculation. As shown in FIG. 1, this cement slurry A is placed on an endless felt belt 5 provided with a suction dewatering device 4 to a thickness of 10 to 13 mm.
It was supplied to a layer 6 having a thickness of 6 mm and transported while being suction-dehydrated. When the surface was dehydrated to such an extent that free water on the surface disappeared, the molded plate was cut by a cutter 7.

The cut formed plate 8 is transferred to a press plate 9.
As shown in FIG. 2, the depth d = 10 cm × 5 cm in a brick joint shape.
Pressing speed of 1 mm / s and 3.5 mm / with a concavo-convex pattern press board 9 of 4 mm and shaping angle θ = 60 ° (hereinafter referred to as mold A).
A compression press was performed under the conditions of s.

After pressing, the molded plate 8 was naturally cured for 24 hours, and then autoclaved at 170 ° C. for 15 hours to obtain a product. The reproducibility of the uneven pattern on the surface of the plate-like product obtained as described above was evaluated by the presence or absence of cracks and the shedding by pressing. The results are shown in the graphs of FIGS.

FIG. 4 shows the evaluation of cracks, and FIG. 5 shows the evaluation of grain shattering.
Means that 10% by weight of normal pearlite was added and 0 for low specific gravity pearlite.

The meanings of the numbers on the axis of evaluation in FIGS. 4 and 5 are as follows: In the case of the crack evaluation in FIG. 4: Fine cracks were observed.

3: Cracks were partially observed. 2: Cracks were observed on the entire surface. 1: Large cracks were observed on the entire surface.

The evaluation was 4 or more. Also,
In the case of the graining evaluation shown in FIG. 5, 5 ... The graining of the raw material particles accompanying the dehydration at the time of pressing was hardly observed. 4: A small amount of particles of the raw material due to dehydration during the drying was observed.

3 ... The raw material particles were degranulated due to dehydration during pressing. 2 ... Draining of raw material particles due to dehydration during pressing was observed on the entire surface. 1: The material particles were severely shattered over the entire surface due to dehydration during pressing.

The evaluation was 4 or more. Also,
The plot points in FIGS. 4 and 5 are measurement points. Further, as shown in the figure, the solid line shows the one with a pressing speed of 1 mm / s, and the one-dot chain line shows the one with a pressing speed of 3.5 mm / s.
Gave a bad result in the evaluation of grain shedding.

As is clear from FIGS. 4 and 5, it was found that when the amount of the low specific gravity inorganic porous particles added was 10% by weight or more, good reproducibility of the uneven pattern was exhibited. [Example 2] As the cement composition, the above-mentioned cement 40% by weight, silica sand 40% by weight, perlite 10% by weight, pulp fiber 10%
A raw material consisting of a general general basic composition in weight% was put into a mixing tank together with water and uniformly mixed to prepare a base layer cement slurry B having a slurry concentration of 25%.

As shown in FIG. 6, this cement slurry B is supplied in a layer 10 having a thickness of 10 to 13 mm on an endless felt belt 5 provided with a suction dewatering device 4, and is conveyed while being suctioned and dewatered. When dehydrated to the extent that disappears,
The same slurry A as shown in Example 1 was supplied in the form of a layer 11 having a thickness of 5 mm on the base cement layer 10 made of the cement slurry B. Immediately thereafter, the formed plate was cut by the cutter 7.

The cut molded plate material 8 is transferred to a press platen 9, and a mold A having the same shape as that of the first embodiment and a depth of 1 mm from the mold A is used.
mm deep d = 5 mm, shaping angle θ = 60 ° (hereinafter referred to as B mold). Compression press at the press press speeds of 1 mm / s and 3.5 mm / s using two types of mold press plates 9 respectively. did.

After pressing, the molded plate material 8 was naturally cured for 24 hours, and then autoclaved at 170 ° C. for 15 hours to obtain a product. The reproducibility of the uneven pattern on the surface of the plate-shaped product obtained as described above was evaluated by the presence or absence of cracks and the presence or absence of particle shedding as in Example 1, and the results are shown in graphs as shown in FIGS. Was.

In FIGS. 7 to 10, the meaning of the solid line, the two-dot chain line, and the meaning of the numbers on the axis of evaluation are shown in FIG.
It is the same as FIG. The term "low specific gravity pearlite 0" means that normal pearlite was added at 10% by weight and low specific gravity pearlite was 0.

As is clear from FIGS. 7 to 10, it was found that the reproducibility of the deeply carved uneven pattern was improved from the composition in which the low specific gravity pearlite was added at 8% by weight or more. However, when examined from the impact strength of the surface of the uneven pattern, when the amount of the low specific gravity inorganic porous particles exceeds about 20% by weight, the strength is considerably reduced, and in the case of the single-layer molding of Example 1, the sheet material strength is also remarkable. The decline was seen. In addition, it was found that Example 2 molded into two layers had better pattern reproducibility.

Therefore, it is found that there is no problem when only the reproducibility of the concavo-convex pattern is required, but when the strength is also required, the production method of Example 2 is preferable. Example 3 Next, five types of slurries of the slurry B of Example 2 were prepared from 10% to 50% in 10% increments, and the moldability of the surface layer was tested.

As a result, at 10%, the solid content of the slurry was too small to form a layer, and at 20% or more, layer formation was possible. When the content exceeds 40%, it has been found that the solid component of the slurry is increased, and it is difficult to transport the raw material by a pump because of the viscosity.

It has been found that the slurry concentration for forming a more efficient layering is 15% to 40%, preferably 20% to 40%. Example 4 Next, the cement slurry A of the surface layer of Example 2
In place of pulp fiber blended in, CSF
A plate was produced in the same manner as in Example 2 using three types of softwood pulp, hardwood pulp with a short fiber length, and cellulose powder each having a volume of 400 ml or less.

As a result, the evaluations of the reproducibility of the pattern and the like were almost the same as those in the graphs of FIGS. Has increased considerably.

[0046]

As described above, according to the first aspect of the present invention, the surface of the fiber reinforced cement plate is easily broken by the inorganic porous particles which are easily crushed, and the uncured plate material immediately before pressing is obtained. Deep engraving can be performed without increasing the fluidity of the surface.

Therefore, it is not necessary to adjust the amount of suction and dewatering, which was difficult to adjust conventionally, and it is possible to easily form a deeply carved uneven pattern. According to the invention of claim 2, the structure of the fiber reinforced cement board is multi-layered. The applicable range of the moisture content can be widened, and as a result, troublesome work for adjusting the surface fluidity at the time of pressing to the optimal fluidity according to the pressing conditions is not required, and the depth of the pressable handle can be reduced. Types of pod inclination and fineness increase.

The inorganic foamed particles added to the upper layer absorb water in the slurry at the time of press crushing and rapidly reduce the fluidity of the slurry after pressing. It is also possible to form a deeply carved uneven pattern with a shape angle.

According to the third aspect of the present invention, in addition to the above-described effects, the upper layer can be reliably formed. According to the fourth aspect of the present invention, the pulp fibers constituting the upper layer are miniaturized, so that engraving is possible. This has the effect that it is possible to press deep and clear uneven patterns.

[Brief description of the drawings]

FIG. 1 is a side view of an apparatus for performing a method according to the first aspect of the present invention.

FIG. 2 is an enlarged sectional view showing an uneven state of the press machine.

FIG. 3 is a graph showing properties of a low specific gravity pearlite used in the present invention.

FIG. 4 is a graph showing crack evaluation of a plate material formed by the method according to the first aspect of the present invention.

FIG. 5 is a graph showing the evaluation of shedding of a sheet material formed by the method according to the first aspect of the present invention.

FIG. 6 is a side view of an apparatus for performing the method according to the second aspect of the present invention.

FIG. 7 is a graph showing a crack evaluation of a plate material formed by the method according to the second aspect of the present invention.

FIG. 8 is a graph showing the evaluation of shedding of a sheet material formed by the method according to the second aspect of the present invention.

FIG. 9 is a graph showing a crack evaluation of another plate material formed by the method according to the second aspect of the present invention.

FIG. 10 is a graph showing the evaluation of particle shedding of another sheet material formed by the method according to the second aspect of the present invention.

FIG. 11 is an explanatory sectional view of a conventional example.

FIG. 12 is an explanatory sectional view of a conventional example.

[Explanation of symbols]

 4 suction dehydrator 5 endless felt belt 6 cement layer of base layer 7 cutter 8 cut formed plate 9 press

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI C04B 28/02 C04B 28/02 // (C04B 28/02 16:02 14:18) 111: 20 (72) Inventor Hiroki Kuwayama 1-1-1 Hama, Amagasaki City, Hyogo Prefecture Inside Kubota Technology Development Laboratory Co., Ltd.

Claims (4)

[Claims] 1. A one-layer flow-on molding method in which a cement slurry is supplied in a layer form on a felt belt equipped with a suction dewatering device, and suction-dewatering is performed to make a plate. 8 to 2 porous particles
After supplying a cement slurry containing 0% by weight on the felt belt and forming a layer, the layer is cut into a size suitable for press molding described below, and the cut uncured fiber reinforced cement board is pressed to form an uneven pattern on the surface. And then curing and curing according to a conventional method. 2. A one-layer flow-on molding method in which a cement slurry is supplied in a layer form onto a felt belt provided with a suction dewatering device, and suction-dewatering is performed to make a plate. In the process of supplying in the form of a layer, suctioning and dehydrating and transporting, the layer is used as a base layer to further supply a cement slurry containing 8 to 20% by weight of inorganic porous particles having a high bulk specific gravity and easily crushed by a pressing pressure described later. After lamination, and cut into dimensions suitable for press molding described below, press the cut uncured fiber reinforced cement board from the upper layer to give an uneven pattern on the upper layer surface,
A method for producing a fiber-reinforced cement board, comprising curing and curing according to a conventional method. 3. The method for producing a fiber-reinforced cement board according to claim 2, wherein the slurry concentration of the upper layer cement slurry is 15 to 40%. 4. The fiber-reinforced cement according to claim 2, wherein the reinforcing fiber added to the upper layer cement slurry is a cellulosic fiber having a short fiber length. Plate manufacturing method.