JP2003251617A - Method for manufacturing of inorganic plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing an inorganic plate which is excellent in surface hardness and smoothness and high in productivity. <P>SOLUTION: A wet inorganic plate of lamina comprising a wet mat obtained by a wet paper machine process from a slurry having a mineral fiber, an inorganic powdery body and a bonding agent as indispensable components or of which at least the front and rear layers are the wet mat, is obtained. Then, after drying the wet inorganic plate to ≤20% in the percentage of a moisture content, the bonding agent is completely hardened by heating and pressurizing. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing an inorganic plate, and more particularly to a method for producing an inorganic plate based on wet papermaking.

[0002]

2. Description of the Related Art Conventionally, as a lightweight and high-strength inorganic plate, there is one disclosed in JP-A-5-50417. However, in the production of the inorganic plate, the thickness was adjusted by pressing with a cold press, then released and dried with a drier. Therefore, springback occurs due to the repulsion of the mineral fibers located in the front and back layers, and a smooth surface cannot be obtained in the front and back layers. As a result, it was necessary to secure the smoothness of the surface and to perform sanding treatment for adjusting the thickness, the grinding amount of sanding was large, the yield was poor, and hard front and back surfaces could not be obtained.

On the other hand, in order to prevent the occurrence of the above-mentioned spring back, it may be possible to press it with a hot press until it completely hardens, but since the front and back layers made by wet papermaking contain a large amount of water, they completely harden. However, there is a problem that it takes a long time and productivity is extremely low.

In view of the above problems, it is an object of the present invention to provide a method for producing an inorganic plate having excellent surface hardness and smoothness and high productivity.

[0005]

Means for Solving the Problems As a result of earnest research to solve the above problems, the present inventors have found that when hot pressing at a predetermined water content or less effectively suppresses springback,
It was found that a highly productive inorganic plate having a hard surface with excellent smoothness can be obtained, and the present invention was completed based on this finding.

In order to achieve the above object, the method for producing an inorganic plate according to the present invention comprises a wet mat obtained by wet papermaking from a slurry containing mineral fibers, an inorganic powder and a binder as essential components. A step of obtaining a wet inorganic plate having a layer, or at least the front and back layers of the wet mat, drying the wet inorganic plate to a water content of 20% or less, and then hot-pressing to completely cure the binder. Is. According to the present invention, the wet inorganic plate is preliminarily dried to a predetermined water content and then hot pressed, so that the front and back layers can be consolidated without causing springback. Therefore, an inorganic plate having desired surface smoothness, thickness accuracy, bending strength and surface hardness can be obtained.

The wet inorganic plate may have a three-layer structure. In particular, the wet inorganic plate having a three-layer structure is preliminarily heated and pressed to predry it to a water content of 20% or less and then hot pressed. It may consist of the step of completely curing the binder. According to this embodiment, an inorganic plate having a three-layer structure can be obtained, and a variety of production methods can be secured.

Further, the method may include a step of applying an aqueous or oily liquid material to at least one surface of a wet inorganic plate dried to a water content of 20% or less and then hot-pressing to completely cure the binder. Good. According to this embodiment,
Since at least one surface is coated with the aqueous or oily liquid, the surface can be softened, and the surface is easily crushed by heat and pressure. Therefore, the surface smoothness is excellent, and the productivity is further improved.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION A method for producing an inorganic plate according to the present embodiment is a method in which a mineral mat, an inorganic powder and a binder are dispersed in water to obtain a wet mat which becomes front and back layers by wet papermaking. obtain. On the other hand, a mixture of an inorganic foam, a fiber and a binder is sprinkled between the wet mats and deposited to form a laminate having an intermediate layer, and then the laminate is dried to a predetermined water content, and then heated, It consists of a pressing process.

The mineral fibers include, for example, rock wool, slag wool, mineral wool, glass wool, etc., and 20 to 60% by weight of the entire front and back layers are added. This is because if it is less than 20% by weight, the inorganic powder cannot be retained and the desired bending strength cannot be obtained. If it exceeds 60% by weight, the amount of the inorganic powder added becomes relatively small. This is because the desired surface hardness cannot be secured.

The inorganic powder is added in order to ensure fire resistance and hardness, and examples thereof include calcium carbonate, aluminum hydroxide, microsilica, slag, etc., and 40 to 70 of the entire front and back layers are included. Wt% is added. If it is less than 40% by weight, the desired surface hardness cannot be obtained, and if it exceeds 70% by weight, the addition amount of the mineral fiber becomes relatively small and the desired bending strength cannot be obtained. is there.

The binder is added to bond the mineral fiber and the inorganic powder, but a binder which is difficult to react while drying the laminate to a predetermined water content is selected. It is preferable. Examples of the binder include melamine resin, phenol resin, poval, epoxy resin, and starch. As an addition amount satisfying both strength and fire resistance, 7 to 15% by weight of the entire front and back layers may be added. preferable.

As the auxiliary additives for the front and back layers, synthetic fibers such as polypropylene, polyester and vinylon,
Examples include plant fibers such as hemp and flax, and wood fibers. Further, for example, any one of a flocculant, a sizing agent and an antifoaming agent may be added, if necessary.

The inorganic foam that forms the middle layer is added to reduce the weight while ensuring the compressive strength.
Examples include perlite, shirasu foam, silica flour, and glass foam, and 40 to 90% by weight of the entire middle layer is added. This is because if it is less than 40% by weight, the weight cannot be reduced, and if it exceeds 90% by weight, the amount of the fibers and binder to be described later becomes relatively small, and the desired strength cannot be obtained. .

The fibers forming the intermediate layer are added to connect the above-mentioned inorganic foams. For example, mineral fibers such as rock wool, slag wool, mineral wool and glass wool, polypropylene, polyester, vinylon, etc. Synthetic fibers, plant fibers such as hemp and flax, and
Wood fiber is mentioned. And, in the middle layer, the fibers are 1
-40% by weight is added. This is because if it is less than 1% by weight, the desired strength cannot be obtained, and if it exceeds 40% by weight, the weight reduction due to the inorganic foam is hindered.

The binder of the middle layer may be made of the same material as that of the front and back layers described above, and may be added in the same amount.

The water added to prepare the mixture for the middle layer is preferably 5 to 30% by weight of the solid component. This is because if it is less than 5% by weight, the powder tends to scatter at the time of mixing and molding, resulting in poor workability.
If it exceeds, the plate is likely to be punctured during the hot pressing during the temporary pressing. Further, generally, the total amount of organic components such as binders and organic fibers must be 15% by weight in order to obtain an inorganic plate which is a semi-incombustible plate, and 7% by weight or less in order to obtain a noncombustible plate.

Next, a method for manufacturing an inorganic plate according to the present invention will be described. First, each material for the front and back layers is put into water and stirred, and then an auxiliary additive such as a coagulant is added to obtain a slurry having a solid content of several%. Then, a wet mat which becomes the front and back layers is obtained from the slurry with a Fourdrinier or roundnet papermaking machine.

On the other hand, various materials for the middle layer are mixed while spraying water to obtain a mixture. Then, this mixture is uniformly sprayed and deposited on the surface of the wet mat to be the surface layer, and then the wet mat to be the back layer is stacked to obtain a three-layer structure laminate.

Then, in order to obtain sufficient shape retention and handling strength, the laminate is temporarily pressed at a predetermined pressure and temperature (80 to 180 ° C.). At this time, it may be a heating roll or a continuous press. Although some springback occurs after this temporary pressing, it does not affect the physical properties of the final product because the hot pressing is performed in the final step.

Next, the laminated body is heated with a hot air dryer (80
˜250 ° C.) to a water content of 20% or less. This is because if it exceeds 20%, the hot-pressing time for final curing becomes long and the productivity decreases. This step does not require the laminate to be completely dried and the binder to be completely reacted. Therefore, the drying can be performed in a short time, and it is possible to simplify the drying equipment while ensuring the improvement of productivity. The water content herein means the ratio of the total dry weight to the value obtained by subtracting the total dry weight from the weight before drying.

The laminated body dried to a predetermined water content is clamped by a hot press at a predetermined pressure, temperature and time. Since the binder is completely cured while applying a predetermined pressure, springback does not occur, the desired thickness accuracy, surface smoothness,
An inorganic plate having excellent physical properties such as surface hardness, density and bending strength can be obtained. In the hot pressing step, since the water content is adjusted to be low in advance, sufficient strength can be obtained in a short hot pressing time, and as a result, an inorganic plate having high productivity can be obtained.

Before final curing with a hot press,
Aqueous or oily liquid is used for the front and back surfaces of the laminate or one side
May be applied to. The flow of binder is promoted and the surface
This is because the lubricity and surface hardness are improved. The aqueous liquid
Examples of the substance include, in addition to fresh water, vinyl acetate emulsion.
A water-soluble resin such as sucrose or PVA can be used. Oily liquid
As, for example, isocyanate type, epoxy type, etc.
Alcohol diluted products can be used. And the liquid material
As the coating amount, one side is 20 to 100 g / m^TwoIs preferred
Yes. 20 g / m^TwoIf it is less than, it is almost effective
No, 100 g / m ^TwoIf it exceeds the limit, it will be troublesome for coating workability.
Because it is too much.

In the above embodiment, the inorganic plate having a three-layer structure has been described. However, a two-layer inorganic plate composed of two wet mats may be used, and a single wet mat may be used. A layered inorganic plate may be used. Further, in order to increase the adhesive strength of the interface portion and improve the peeling strength, a binder may be applied to the interface between the front and back layers and the middle layer so as to be laminated and integrated.

[0025]

Example 1 Rock wool 50%, aluminum hydroxide 40%, powdered phenol 6%, starch 4%
Was stirred in water, a flocculant was added to cause flocculation, and then papermaking was performed to prepare two wet mats for the front and back layers. At this time, the wet mat had a water content of 80%. On the other hand, pearlite 55%, aluminum hydroxide 34%, pulp 1
%, Powdered phenol 6% and starch 4% were uniformly mixed while spraying water (10% by weight of solid component) to obtain a mixture for the middle layer. Then, the mixture was uniformly sprayed and deposited on the wet mat for surface layer, and the wet mat for back layer was stacked thereon to obtain a laminate. This laminated body is 6.6 m
9 by hot pressing at 90 ° C through the distance bar of m.
Temporary clamping was performed for 0 seconds. Then, it was dried with a dryer at 150 ° C. for 10 minutes to obtain a laminate having a water content of 10%. Finally, one side of each of the front and back surfaces of the laminate is 50 g / m ²
After evenly applying the above water, it is pressed with a hot press at 200 ° C. for 3 minutes through a 6.6 mm distance bar,
A three-layer inorganic plate having a thickness of 6.6 mm was obtained and used as a sample. Then, the physical properties of the sample were measured.
The measurement results are shown in FIG. The weight of each layer was: surface layer: middle layer: back layer = 1.7: 1.3: 1.7 (kg / m ² ). Furthermore, when the front and back surfaces of the sample were visually observed, no springback was found.

(Embodiment 2) 15 minutes for 10 minutes without temporary pressing
The laminate was dried with a dryer at 0 ° C. and the moisture content of 10% was pressed for 3 minutes under the same conditions as in Example 1 to obtain a 6.6 mm-thick three-layer inorganic plate, which was used as a sample. Then, the physical properties of the sample were measured. The measurement results are shown in FIG. The weight of each layer is as follows: surface layer: middle layer: back layer = 1.7:
It was 1.3: 1.7 (kg / m ² ). Furthermore, when the front and back surfaces of the sample were visually observed, no springback was found.

(Example 3) Two sheets of wet lubricating mats for front and back layers obtained by treating in the same manner as in Example 1 were directly laminated to obtain a laminate. This laminate was provisionally pressed for 90 seconds with a hot press at 90 ° C. through a 5 mm distance bar. Then, it was dried with a dryer at 150 ° C for 10 minutes to obtain a water content of 1
A 0% stack was obtained. And 3.3 mm in the laminated body
Through a distance bar at 200 ° C in a hot press
It was pressed for a minute to obtain a two-layered inorganic plate having a thickness of 3.3 mm, which was used as a sample. Then, the physical properties of the sample were measured. The measurement results are shown in FIG. The weight of each layer was front layer: back layer = 2.0: 2.0 (kg / m ² ). In addition, when the front and back surfaces of the sample were visually observed, no springback was found.

(Comparative Example 1) Rock wool 50%, aluminum hydroxide 39%, powdered phenol 6%, starch 4
%, Isocyanate group-containing binder (polymeric MD
I) 1% was stirred in water, a flocculant was added to cause flocculation, and then papermaking was performed to prepare two wet lubricating mats for front and back layers. At this time, the water content of the mat was 80%. on the other hand,
55% of pearlite, 34% of aluminum hydroxide, 1% of pulp, 6% of powdered phenol and 4% of starch were uniformly mixed while spraying water (10% by weight of solid component) to obtain a mixture for middle layer. Then, the mixture was uniformly sprayed and deposited on the wet mat for surface layer, and the wet mat for back layer was stacked thereon to obtain a laminate. This laminate is 6.6
Temporary pressing was performed for 90 seconds with a 90 ° C. hot press through a mm distance bar. Then, it was dried with a dryer at 150 ° C. for 30 minutes to completely cure the binder to obtain an inorganic plate having a three-layer structure, which was used as a sample. Then, the physical properties of the sample were measured. The measurement results are shown in FIG. The weight of each layer is as follows: surface layer: middle layer: back layer = 1.8: 1.5:
It was 1.8 (kg / m ² ). Then, when the front and back surfaces of the sample were visually observed, generation of springback was confirmed.

Further, in order to use each of the above-mentioned samples as a base material for cosmetics, high surface smoothness and thickness accuracy are required. For this reason, the sanding process was performed on the front and back surfaces, and then the finishing process was performed. In Examples 1 to 3, since the binder was finally cured during the hot pressing, there was no springback of the mineral fibers, and the thickness accuracy and surface smoothness were excellent. Therefore, the total grinding amount of Examples 1 to 3 was smaller than that of Comparative Example 1.

As is clear from the measurement results shown in FIG. 1, according to Examples 1 to 3, it was found that an inorganic plate excellent in bending strength and surface hardness could be obtained. Furthermore, Examples 1-3
According to the above, it was found that there is no springback, and an inorganic plate excellent in surface smoothness and thickness accuracy can be obtained. Also,
It has been revealed that these characteristics are very preferable in terms of workability and quality when finishing processing a decorative material and the like, and in particular, the amount of sanding is small and the material yield is remarkably improved. Further, since the laminated body is dried to a low water content and then hot pressed, the pressing time by the hot pressing is very short and the productivity is excellent. In particular, if a multi-stage press is used, it can be dried more efficiently. Furthermore, in the case of Example 3 having no middle layer,
Although the mineral fibers in the laminate occupy more than half of the weight, they are temporarily pressed and finally hardened by a hot press. For this reason,
Not only an inorganic plate with high specific gravity and high physical properties can be obtained, but also the pressing time is short and the productivity is high. Further, it has been found that it is not necessary to add an isocyanate adhesive in order to prevent springback, so that the composition can be simplified and the release problem of the press board can be reduced.

[0031]

According to the present invention, the wet inorganic plate is preliminarily dried to a predetermined water content and then hot pressed. Therefore, the front and back layers can be consolidated without generating springback. As a result, there is an effect that an inorganic plate having desired surface smoothness, thickness accuracy, bending strength and surface hardness can be obtained.

[Brief description of drawings]

FIG. 1 is a chart showing measurement results of examples and comparative examples.

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Claims (4)

[Claims] 1. A single layer of a wet mat obtained by wet papermaking from a slurry containing mineral fiber, an inorganic powder and a binder as essential components, or a wet inorganic material in which at least front and back layers are the wet mat. A method for producing an inorganic plate, which comprises obtaining a plate, drying the wet inorganic plate to a water content of 20% or less, and then heat-pressing to completely cure the binder. 2. The method for producing an inorganic plate according to claim 1, wherein the wet inorganic plate has a three-layer structure. 3. The wet inorganic plate having a three-layer structure is preliminarily heated and pressed to predry it to a water content of 20% or less, and then hot pressed to completely cure the binder. 2. The method for producing an inorganic plate according to 2. 4. A wet inorganic plate dried to a water content of 20% or less is coated with an aqueous or oily liquid on at least one side and then hot pressed to completely cure the binder. 4. The method for producing an inorganic plate according to any one of items 1 to 3.