JPH0516385B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to an inorganic fiberboard that is lightweight and has a hard surface layer, and a method for manufacturing the same. (Conventional technology and its problems) Conventionally, inorganic fiberboards obtained by making inorganic fibers such as rock wool and slag wool into an aqueous slurry are lightweight and have excellent heat insulation, fireproofing, and sound absorption properties. Because of this, it is widely used as ceiling materials, sound-absorbing boards, and other building materials. However, inorganic fibers are brittle and break easily, so when the fiberboard is subjected to compressive force or impact, the fibers break and the voids between the fibers collapse, easily causing dents and scratches on the surface layer. In addition, when nailing or screwing inorganic fiberboard,
Not only does the nail head or screw head sink into the surface layer, resulting in a poor appearance, but also the installation strength is reduced. In order to eliminate such problems, the overall density of the inorganic fiberboard may be increased, but this will impair its heat insulation properties and workability such as cutting. For this reason, a method was developed to harden only the surface layer of the inorganic fiberboard. As such methods, there are a method of impregnating the surface layer of the inorganic fiberboard with a resin liquid to strengthen it, and a method of forming a thin layer of high-density fibers on the surface of the wet mat when making the inorganic fiberboard. The fiberboard obtained by the latter method has a problem in that its fire retardant properties are reduced and it tends to warp due to the difference in linear expansion coefficient due to moisture absorption between the inorganic fiberboard and the resin layer. There is a problem in that the papermaking equipment becomes complicated. In addition to this method, there is also a method of forming a hard coating film on the surface of the inorganic fiberboard by painting, but in order to form a hard coating film, the resin concentration must be 10% or more in solid content. Because it is necessary to apply a highly viscous paint, the expansion and contraction rates of the paint film and the inorganic fiberboard are different, causing warping due to moisture absorption and drying, slowing down the application and drying speeds and reducing productivity. decreases. Furthermore, the thickness of the coating film was increased by 50
When the thickness is ~100μ, scratches are less likely to occur on the surface, but since the inorganic fiberboard itself is soft, it is not possible to eliminate the occurrence of dents due to compression. The object of the present invention is to provide an inorganic fiberboard and a method for manufacturing the same that solve these problems. (Means for Solving the Problems) In order to achieve the above object, the inorganic fiberboard of the present invention has an inorganic powder with a particle size of 1 to 5μ on the surface layer of an inorganic fiberboard with a specific gravity of 0.3 to 0.5. is filled in a substantially uniform layer from the surface of the inorganic fiberboard to a depth of 1 to 5 mm, and the voids between the inorganic fibers in the surface layer of the inorganic fiberboard are substantially filled with the inorganic powder. This inorganic fiberboard manufacturing method involves wet papermaking of an aqueous slurry mainly composed of inorganic fibers such as rock wool and slag wool, and then applying a layer of particles having a particle size of 1 to 5 μm to the surface of wet pine. After applying water-insoluble inorganic powder in the form of an aqueous dispersion with a concentration of 3 to 30% at a coating amount of 200 to 2000 g/m ² , the lower surface of the wet pine is coated. By suctioning from the side to dehydrate the water in the wet pine and at the same time sucking in the dispersion of the inorganic powder, the powder is applied from the surface of the inorganic fiberboard to the voids between the inorganic fibers in the surface layer of the wet pine. It is characterized in that it is filled to a depth of ~5 mm and then dried. (Function) Since the surface layer of the inorganic fiberboard is filled with inorganic powder having a particle size of 1 to 5μ in a substantially uniform layer,
The hardness of the surface layer of the fiberboard is increased without substantially impairing the weight reduction of the inorganic fiberboard, and the installation strength by nailing etc. is improved, and the occurrence of surface dents due to compressive force or impact force is prevented. Furthermore, since the inorganic powder is filled in the gaps between the inorganic fibers, the fire retardant properties, workability, heat insulation properties, etc. of the inorganic fiberboard are not impaired, and it is also resistant to moisture absorption and desorption and drying. Inorganic powder expands,
Since it does not shrink, it does not warp. In addition, such an inorganic fiberboard is produced by applying an inorganic powder in the form of a low-concentration aqueous dispersion onto the surface of a wet mat obtained by wet papermaking, and dewatering the wet mat from the underside using a vacuum suction device. As a result, the wet mat can be filled to a predetermined depth by utilizing the movement of water in the wet mat, so that it can be continuously filled during the wet mat dewatering process, and productivity can be improved. (Example) To explain the example of the present invention with reference to the drawings, 1
is an inorganic fiberboard with a specific gravity of 0.3 to 0.5, and in the gaps between the inorganic fibers in the surface layer from the surface to a depth of 1 to 5 mm, there is a large number of inorganic powders with a particle size of 1 to 5 μm2, 2...2 are filled in a buried state, and the space between the inorganic fibers is substantially filled with these inorganic particles 2 to form a hard surface layer portion 3. In order to obtain such an inorganic fiberboard, first, an aqueous slurry mainly composed of inorganic fibers such as rock wool or slag wool is wet-formed, and the water content is 70%.
% or more of wet mat 1a is formed. The slurry concentration and paper-making speed are adjusted in advance so that the fiber density in the wet mat is 0.5 g/cm ² or less. In addition, the water content is set to a high water content of 70% or more so that the water in the wet mat can easily flow to the lower surface. Next, 3 to 30% of inorganic powder 2 with a particle size of 1 to 5 μm is applied to the surface of the wet mat obtained in this way.
The powder is applied in the form of a concentrated aqueous dispersion in an amount of 200 to 2000 g/m ² in terms of solid content. It is preferable to apply the coating amount to approximately the same amount as the moisture content of the wet mat so that the moisture and powder can be easily transferred. The inorganic powder 2 is not preferably one that becomes gel-like in water and has a high viscosity; it is preferable to use one that is insoluble in water, has good dispersibility in water, and has good drainage. Examples of the material 2 include calcium carbonate, silica sand, microsilica, slag powder, wollastonite, fly ash, aluminum hydroxide, shirasu, and dihydrate gypsum. Furthermore, if the particle size of the inorganic powder 2 is less than 1 μm, the inorganic powder 2 will be dispersed and penetrated into the entire interior of the wet mat, making it impossible to selectively form a hard layer only in the surface layer. Furthermore, in the case of inorganic powders such as pearlite and mica with a particle size of 5μ or more, just a powder layer of about 0.2 mm thick on the surface of the inorganic fiberboard can penetrate into the inside of the inorganic fiberboard. Since it cannot be filled, it falls off the surface after drying. Therefore, the inorganic powder 2 used has a particle size in the range of 1 to 5 microns as described above. The concentration of the dispersion to be applied is 30% or less so that the inorganic powder migrates into the surface layer of the wet mat with the movement of water. That is, if the concentration exceeds 30%, the movement of water is small and the powder remains in a layer on the surface. After the aqueous dispersion of the inorganic powder 2 with a low concentration is applied to the surface of the wet mat 1a, air is sucked in from the bottom side of the wet mat 1a by a vacuum suction device to dehydrate the water in the wet mat, and at the same time the inorganic powder 2 The aqueous dispersion is sucked into the inside of the wet mat to penetrate between the inorganic fibers and fill them. At this time, as mentioned above, since the particle size of the inorganic powder 2 is in the range of 1 to 5 μm, the suction force during dehydration causes the inorganic powder 2 to move from the surface of the wet mat 1a to 1 to 5 μm. It easily penetrates to a depth of 5 mm and is uniformly filled to the extent that the voids between the inorganic fibers are substantially filled. Next, the surface of the wet mat 1a whose surface layer is filled with the inorganic powder 2 is sprayed with a dilute resin solution (1 to 5% Prevent powder from falling off by applying a binder solution such as aqueous starch solution or aqueous starch solution. The amount of resin liquid to be applied is 5 per ¹ m2 in order to prevent the powder from falling off due to vibration etc.
~10g (solid content) is sufficient. Even without such surface treatment, as mentioned above, the inorganic powder is buried deep inside the surface layer of the wet mat, so there is no chance of it falling out in a way that affects the surface hardness. It never happens. Thereafter, the wet mat 1a is dried using a dryer or the like to obtain an inorganic fiberboard 1 whose surface layer is hardened by the inorganic powder.
Next, specific examples and comparative examples of the present invention will be shown. Example 1 A 2% aqueous slurry of rock wool was made into a paper using a circular paper machine to form a 10 mm thick wet mat with a moisture content of 150%, and a powder having the following composition was coated on the surface of the wet mat. 4000ml/m ² of powder (powder concentration 5%) (200g powder application amount)
It was supplied and applied uniformly at a ratio of . Calcium carbonate powder (particle size 1-3μ...40%) (particle size 4-5μ...60%) 5 parts by weight Water 94 parts by weight Melamine resin 1 Immediately after applying the powder dispersion to the surface of the wet pine A vacuum suction device is used to draw air into the wet pine from the underside, and at the same time the moisture inside the wet pine is dehydrated, the powder dispersion applied to the surface is sucked to determine the moisture content of the wet pine.
After dehydration to 82%, the powder dispersion was infiltrated into the surface layer of the wet mat to a depth of 3 mm by suction force, and the powder in the dispersion was filled into the voids of the fibers. Next, the dehydrated wet pine was dried with a dryer to obtain an inorganic fiberboard with an average specific gravity of 0.41. Example 2 The powder concentration of the powder dispersion in Example 1 was changed to 8%, and this dispersion was applied to the surface of a wet mat of rock wool obtained in the same manner as in Example 1.
Apply the powder at a rate of 16000ml/m ² (1300g/m ² in terms of powder application amount), immediately suck it up from the underside, dehydrate it, fill the powder to a depth of 3mm from the wet mat surface, dry it, and An inorganic fiberboard with a specific gravity of 0.43% was obtained. In addition, the specific gravity of the inorganic fiberboard itself which is not filled with powder in Examples 1 and 2 is 0.39. Comparative Example 1 An aqueous slurry of rock wool with a concentration of 2% was made using a round rope paper making machine to form a 10 mm thick wet mat with a moisture content of 150%, and the surface layer of the wet mat was not impregnated with powder. It was dehydrated and dried to obtain an inorganic fiberboard with a specific gravity of 0.41. Comparative Example 2 A 2% aqueous slurry of rock wool is made into a 10mm thick paper with a moisture content of 150% using a circular paper making machine.
A wet mat was formed, and the surface layer of the wet mat was dehydrated and dried without powder impregnation treatment to obtain an inorganic fiberboard with a specific gravity of 0.43. Comparative Example 3 A 2% concentration aqueous slurry of rock wool is made into a 10 mm thick wet mat with a water content of 150% by using a circular paper making machine, and 200 g of a 30% concentration melamine resin liquid is applied to the surface of this wet mat. /m ² to obtain an inorganic fiberboard with a specific gravity of 0.39 whose surface was reinforced with resin. A comparison of the physical properties of the inorganic fiberboards obtained in the above Examples and Comparative Examples is shown below.

[Table] In the above table, surface hardness is the force required to press-fit a steel ball with a diameter of 50 mm to a depth of 3 mm from the surface of the inorganic fiberboard, and the penetration depth of the nail head is the force required to press-fit a steel ball with a diameter of 50 mm to a depth of 3 mm from the surface of the inorganic fiberboard. This is the depth of penetration when applied. As is clear from this table, the inorganic fiberboard of the present invention has high surface hardness, and high density is achieved by filling the surface layer of the inorganic fiberboard with powder. As there is no difference in the coefficient of linear expansion with respect to the inorganic fiberboard, there is no warpage and the dimensional stability is excellent. (Effect of the invention) As described above, the inorganic fiberboard of the present invention has a specific gravity of
The particle size is 1 to 5μ in the surface layer of the 0.3 to 0.5 inorganic fiberboard.
of inorganic powder from the surface of the inorganic fiberboard.
The inorganic fiberboard is packed almost uniformly in a layer to a depth of 5 mm, and the voids between the inorganic fibers in the surface layer of the inorganic fiberboard are substantially filled with the inorganic powder, which reduces the weight of the inorganic fiberboard. The inorganic powder filled into the surface layer can increase the hardness of the surface without damaging the surface layer, preventing the nail head from digging into the surface layer even when nailing, etc., and increasing the installation strength. Moreover, it can prevent the occurrence of surface dents due to compressive force and impact force,
Furthermore, instead of surface reinforcement through resin impregnation or coating, high density is achieved by filling powder between the fibers on the surface layer of the inorganic fiberboard, which improves processability, sound absorption, heat insulation, and fire resistance. It does not impair its properties, does not warp due to moisture absorption or desorption or drying, and has excellent dimensional stability. In addition, such an inorganic fiberboard can be produced by applying an inorganic powder in the form of an aqueous dispersion onto the surface of a wet mat obtained by wet papermaking, and then sucking air from the underside of the wet mat using a vacuum suction device. Since powder filling can be performed at the same time as dehydration by utilizing the movement of moisture in the wet mat, productivity can be improved by carrying out the filling process continuously during the dehydration process.

[Brief explanation of the drawing]

The drawings show embodiments of the present invention; FIG. 1 is a simplified vertical sectional view of an inorganic fiberboard, FIG. 2 is an enlarged sectional view of the surface layer thereof, and FIG. 3 is an explanatory diagram showing the manufacturing process. 1... Inorganic fiberboard, 1a... Wet mat, 2... Inorganic powder, 3... Hard surface portion.

Claims (1)

[Scope of Claims] 1. Inorganic powder with a particle size of 1 to 5 μ is layered almost uniformly on the surface layer of an inorganic fiberboard with a specific gravity of 0.3 to 0.5 to a depth of 1 to 5 mm from the surface of the inorganic fiberboard. An inorganic fiberboard characterized in that the voids between the inorganic fibers in the surface layer of the inorganic fiberboard are substantially filled with the inorganic powder. 2. Water-insoluble inorganic powder with a particle size of 1 to 5 μm is applied to the surface of wet pine obtained by wet papermaking of an aqueous slurry mainly composed of inorganic fibers such as rock wool and slag wool at a concentration of 3 to 30%. After applying the powder in the form of an aqueous dispersion at a coating amount of 200 to 2000 g/m ² , suction is applied from the underside of the wet mat to dehydrate the water in the wet mat and at the same time form an inorganic powder. By suctioning the body dispersion liquid, the voids between the inorganic fibers on the surface of the wet pine are filled with the powder to a depth of 1 to 5 mm from the surface of the inorganic fiberboard, and then dried. Method for manufacturing inorganic fiberboard. 3. The method for producing an inorganic fiberboard according to claim 2, characterized in that a binder such as a synthetic resin or starch is mixed in the aqueous dispersion of the inorganic powder at a proportion of less than 5%.