JPH09193253A - Moisture absorbing and discharging fiberboard and production thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a moisture absorbing and discharging fiberboard having excellent in moisture absorbing and discharging properties, reduced in moisture absorbing dimen sional change and having sufficient strength in moisture absorption by using a thermo plastic resin being a composite of an acrylic acid resin and a polyolefinic resin and having moisture absorbing and discharging properties, a fiber substance and a binder for the fiber substance as essential components. SOLUTION: In a moisture absorbing and sicahrging fiberboard, a fiber substance is bonded by a binder and a thermoplastic resin having moisture absorbing and discharging properties is arranged along the fiber substance. As the thermoplastic resin having moisture absorbing and discharging properties, a composite of an acrylic acid resin and a polyolefinic resin is used. Therefore, a raw material consisting of the fiber substance, the thermoplastic resin being the composite of the acrylic acid resin and the polyolefinic resin and the binder as essential components is dispersed in water to prepare a slurry which is, in turn, subjected to a wet papermaking process to produce a wet mat and, subsequently, the wet mat is dried at temp. higher than the softening and melting temp. of the thermoplastic resin and the binder is cured to bond the fiber substance and the thermoplastic resin is arranged along the fiber substance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moisture absorptive and desorptive fiberboard used as a ceiling panel, a wall panel or the like for adjusting indoor humidity, and a method for producing the same.

[0002]

2. Description of the Related Art Moisture absorbing / releasing fiberboards are used for ceiling panels, wall panels, etc. in order to control indoor humidity, prevent dew condensation, and obtain a comfortable environment. Conventionally, in order to improve the moisture absorption and desorption of wood fiber boards and mineral fiber boards, highly water-absorbent resin powders such as cross-linked starch / acrylate graft copolymers and cross-linked acrylates have been added. The particles are located in the voids between the fibers and swell up to about 20 times when absorbing moisture or water, so that the distance between the fibers increases and the dimensional change of the plate material increases. Further, along with this, peeling of the binder or the like is caused, so that the strength at the time of absorbing moisture also decreases.

Further, in order to improve the moisture absorption and desorption properties of these base materials, when a pin hole or a cutting groove is provided on the surface to expose the fibers and the voids between the fibers to the outside air, a highly water-absorbent resin existing between the fibers. The powder is spilled from the pin hole or the cutting groove to the outside, so that not only the performance is deteriorated, but also when it is used as a ceiling material, the resin powder is scattered due to vibration and the like to pollute the room.

[0004]

Therefore, there is a demand for a moisture absorptive and desorptive fiberboard which has an excellent moisture absorptive and desorptive property, a small change in moisture absorptive dimension, and a sufficient strength even during moisture absorption.

[0005]

The moisture absorptive and desorptive fiberboard of the present invention is a composite of an acrylic resin and a polyolefin resin and has a moisture absorptive and desorptive thermoplastic resin, a fiber substance, and the fiber substances themselves. The binding agent that binds is an essential component.

Further, the moisture absorptive and desorptive fiberboard of the present invention is a moisture absorptive and desorptive fiberboard in which fibrous substances are bound by a binder, and a thermoplastic resin having a moisture absorptive and desorptive property is arranged along the fibrous substances. It is characterized by Further, a composite of acrylic acid resin and polyolefin resin is used as the thermoplastic resin having moisture absorption and desorption properties.

According to this structure, the thermoplastic resin having moisture absorbing / releasing property is arranged along the fiber even if it absorbs moisture or absorbs water, so that it swells along the fiber. Therefore, since the fibers are not spread very much (most of them swell in the space), the dimensional change is small and the moisture absorption / water absorption strength is not significantly reduced.

Further, the moisture absorbing / releasing fiber board is characterized in that at least either a pin hole or a cutting groove is provided on the surface. By exposing the fibers and the voids between the fibers to the outside air by providing pin holes and cutting grooves, it becomes easy for moisture to directly adsorb and desorb from the thermoplastic resin with moisture absorbing and desorbing properties that covers the fibers. Speed increases. Moreover, since the thermoplastic resin does not exist in the powder state as in the past, but is arranged along the periphery of the fiber, the pin hole provided on the surface of the moisture absorptive and desorptive fiber board even if vibration or the like occurs. It does not spill out from the cutting groove. Therefore, the moisture absorption / desorption property does not deteriorate and the interior is not stained.

In the method for producing a moisture absorptive and desorptive fiberboard of the present invention, a raw material containing a fiber substance, a thermoplastic resin which is a composite of an acrylic acid resin and a polyolefin resin, and a binder is dispersed in water. The wet mat is manufactured by wet-paper-making the slurried material, and then the wet mat is dried at a temperature higher than the softening and melting temperature of the thermoplastic resin to cure the binder and bond the fibrous substances to each other. In addition, the thermoplastic resin is arranged along the fiber material.

As a result, it is possible to obtain the moisture absorptive and desorptive fiber board described in claim 1, claim 2, and claim 3.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to preferred embodiments. [Example 1] A wet mat was obtained by wet-paper-making a material obtained by dispersing the raw materials shown in Table 1 in water to form a slurry using a gauze machine. The paper-making method itself is the same as the conventional one, and a small amount of paper-making chemicals such as a flocculant and an antifoaming agent was added. As the highly moisture absorbing / releasing resin powder, a thermoplastic resin in which a sodium polyacrylate type and a polyolefin type were blended was used. The melting point of this thermoplastic resin is 94 ° C.

The addition amount of the high moisture absorbing / releasing resin powder is 0.1 to 0.1% of the total amount.
About 10% is preferable. This is because if it is 0.1% or less, sufficient moisture absorbing / releasing performance cannot be obtained, and if it is 10% or more, it absorbs too much moisture and the dimensional change rate of moisture absorption becomes large, making it difficult to secure sufficient moisture absorbing bending strength. Is.

The wet mat is dried at a temperature higher than the softening and melting temperature of the thermoplastic resin by a hot air circulation type dryer.
The water contained at this time evaporates, and the thermoplastic resin is softened and melted and positioned along the rock wool. Further, starch, which is a binder, binds fibers by being dried and cured after containing gelatin with water.

The surface of the obtained plate-like material is polished with a sander to make it smooth, and the thickness is adjusted. Then, the product was cut into a predetermined product size, and after coating, groove processing and pin hole processing were performed by an embossing press.

Example 2 Example 1 until obtaining a plate-like material
Except that the surface of the fibers and the voids between the fibers are exposed to the outside air by performing pin hole processing and cutting groove processing on the surface. Either coating or cutting groove processing may be performed first.

[Comparative Example 1 and Comparative Example 2] For comparison, Comparative Example 1 having the same structure as in Example 1 except that the high moisture-absorption / desorption resin powder was not included, and instead of the high moisture-absorption / desorption resin powder, Comparative Example 2 was prepared in the same manner as in Example 1 except that the same amount of the conventional starch / acrylic acid salt graft copolymer crosslinked product which was a particulate superabsorbent resin powder was added.

[0017]

[Table 1]

[Comparative Test] The above-mentioned Example 1, Example 2,
Various tests were performed on Comparative Example 1 and Comparative Example 2. First, the moisture absorption and desorption performance is 24 in an environment of 25 ° C and 50% humidity.
The weight change was measured when the aged sample was placed in an environment of 25 ° C. and a humidity of 90% for 24 hours.

The rate of dimensional change due to moisture absorption was measured using a microscope by reading the change in length in an environment of 45 ° C. and a humidity of 50% and in an environment of 45 ° C. and a humidity of 90%.

The bending fracture load was measured with a bending fracture tester in an air-dried state at 25 ° C. and a humidity of 50% and in a moisture absorption state after being left in an environment of 30 ° C. and a humidity of 90% for 48 hours.
Table 2 shows the measurement results.

[0021]

[Table 2]

From the test results, Comparative Example 1 which does not contain the highly moisture-absorbing and desorbing resin powder has a low moisture-absorbing and desorbing performance, and Comparative Example 2 which uses the conventional particulate highly water-absorbing resin powder has a large moisture absorption dimensional change rate. ,
Hygroscopic bending strength is low.

It can be seen that in Example 1, although the moisture absorption / release performance was higher than that in Comparative Example 2, the moisture absorption dimensional change rate was small and the moisture absorption bending strength was not reduced.

The moisture absorbing / releasing performance of the second embodiment is further improved than that of the first embodiment. Since the amount of moisture absorption increases as the cutting groove is machined, the rate of dimensional change in moisture absorption is slightly higher than in Example 1 and the bending strength due to moisture absorption is also reduced, but there is no problem in practice. .

[0025]

As described above, according to the present invention, it is possible to obtain a moisture absorptive and desorptive fiberboard which has an excellent moisture absorptive and desorptive property, a small change in the moisture absorptive dimension, and a sufficient strength even during the moisture absorption.

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Claims (5)

[Claims] 1. A moisture absorptive and desorptive fiber comprising a thermoplastic resin having a moisture absorptive and desorptive property, which is a composite of an acrylic acid resin and a polyolefin resin, a fibrous substance and a binder for binding the fibrous substances to each other as essential components. Board. 2. A moisture absorptive and desorptive fiber board in which fibrous substances are bound by a binder, wherein a thermoplastic resin having a moisture absorptive and desorptive property is arranged along the fibrous substances. Wet fiberboard. 3. The moisture absorptive and desorptive fiber board according to claim 2, wherein the thermoplastic resin having a moisture absorptive and desorptive property is a composite of an acrylic acid resin and a polyolefin resin. 4. The surface is provided with at least either a pin hole or a cutting groove for exposing the fibers and the voids between the fibers to the outside air. A hygroscopic fiber board as described. 5. A wet material is prepared by dispersing a raw material containing a fibrous substance, a thermoplastic resin, which is a composite of an acrylic acid resin and a polyolefin resin, and a binder as essential components in water to form a slurry. A wet mat is produced, and then the wet mat is dried at a temperature higher than the softening and melting temperature of the thermoplastic resin to cure the binder to bond the fibrous substances to each other and also to melt the thermoplastic resin to form the fibrous substance. A method for producing a moisture absorptive and desorptive fiber board, which is characterized by being arranged along a line.