JPH0718089A - Lignocellulose molding of low specific gravity and production thereof - Google Patents

Abstract

PURPOSE:To provide a method for producing a stable, optionally shaped molding having a specific gravity as low as 0.3 or less from a lignocelluose of sliced pieces which to not entrangle together. CONSTITUTION:A lignocellulose of sliced pieces that do not entrangle together is treated in an aqueous solution of a chloride or sulfate of magnesium, zinc, aluminum or iron, and then dried. The lignocellulose of sliced pieces is immersed in a mixed aqueous solution of a water-soluble hydroxylic polymer and a water- soluble carboxylic polymer and then taken out. The resultant lignocellulose of sliced pieces is inserted into a specified mold so as to be shaped, and the lignocellulose in this state is dried by heating in a temperature range of 80-180 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low specific gravity lignocellulosic molded article and a method for producing the same.

[0002]

2. Description of the Related Art Cellulose is a high molecular weight carbohydrate (polysaccharide) which is an essential component of plant tissues and fibers. Wood cellulose is commonly referred to as lignocellulose because it is associated with lignin. This lignocellulosic material is, for example, cutting scraps produced during lumber processing of wood, back plates, thinned wood,
It is obtained by crushing bark, waste wood, etc. As a part of such effective use of lignocellulose, urea resin, melamine resin, adhesive such as phenol resin or propylene resin, urethane resin,
A technique is widely known in which, for example, boards are manufactured by mixing vinyl chloride resin and the like and then molding the mixture under heating and pressurizing conditions.

[0003]

When boards are produced from the above-mentioned lignocellulose, the specific gravity of the lignocellulose molding is usually 0.4 or more, and pressurization under conventional heating is applied. It is difficult to produce a lignocellulose molded product having a lower specific gravity than that depending on the molding method. Generally, in order to produce a molded product having a low specific gravity, for example, a method of mechanically pulping wood such as a fiber board or a method of making fibers into thin fibers by a steam defibration method and intertwining them into a thin fiber shape The method of joining to each other is adopted. However, the lignocellulose obtained by crushing the above-mentioned wood chips, back plate, thinned wood, bark, waste wood, etc., is a thick lignocellulose piece with a thickness in the range of 0.3 to 5 mm. Therefore, it is difficult to entangle and form such thick lignocellulosic pieces. Therefore, a method of applying pressure to the lignocellulosic piece and then pressure-molding it under heating is generally adopted, but in this case as well, a molded product having a low specific gravity of 0.3 or less and good shape stability. The reality is that they have not been obtained.

A hydrophilic material such as lignocellulose is heated and pressurized after being immersed in an aqueous solution of a water-soluble adhesive such as polyvinyl alcohol (PVA), sodium acrylate, oxidized starch, carboxymethyl cellulose (CMC),
It is possible to evaporate water to obtain a desired molded product. However, even in this case, if it is attempted to improve the shape stability of the molded product, the specific gravity becomes 0.3 or more, and further, the shape stability in water is remarkably poor. . Particularly in the case of a porous lignocellulosic material that easily absorbs water, the adhesive solution is permeated and absorbed by the lignocellulose, and thus a molded product having a stable shape cannot be obtained.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been proposed in view of the above-mentioned drawbacks inherent in the prior art, and it is proposed to solve this problem by using, as a raw material, lignocellulose in the form of a piece that does not get entangled with each other. It is an object of the present invention to provide a method for producing a molded article having a low specific gravity of 3 or less and having good stability, and a molded article exhibiting water resistance capable of maintaining a stable shape even in water at 50 ° C.

[0006]

[Means for Solving the Problems] Overcoming the above-mentioned problems,
In order to achieve the intended purpose, the low specific gravity lignocellulosic molded article according to the present invention is made of strip-shaped lignocellulose that does not entangle with each other, and magnesium, zinc, aluminum, an iron chloride or sulfate aqueous solution. After being treated with, it is dried, immersed in a mixed aqueous solution of a water-soluble polymer having a hydroxyl group and a water-soluble polymer having a carboxyl group, and then 80-180 in a state of being shaped in a required mold.
It is characterized in that it is heated and dried in a temperature range of 0 ° C. and has a specific gravity of 0.3 or less and stable shape retention in water at 50 ° C.

In order to overcome the above-mentioned problems and achieve the intended purpose, a method for producing a low specific gravity lignocellulosic molded article according to another invention of the present application is to produce a strip-shaped lignocellulose that does not entangle with each other. , Magnesium, zinc, aluminum, iron chloride or sulfate after being treated with an aqueous solution, it is dried to obtain the strip-shaped lignocellulose,
After immersing in a mixed aqueous solution of a water-soluble polymer having a hydroxyl group and a water-soluble polymer having a carboxyl group, this is taken out, and the strip-shaped lignocellulose is inserted into a required mold and shaped, It is characterized in that it is heated and dried within a temperature range of 80 to 180 ° C.

[0008]

EXAMPLES Next, a low specific gravity lignocellulosic molded article and a method for producing the same according to the present invention will be described below with reference to preferred examples. In the case of producing a low specific gravity lignocellulosic molded product from the above-mentioned non-entangled lignocellulose segment as a raw material, an adhesive is selectively deposited at the mutual joints in these lignocellulose segments, and at 50 ° C. It is necessary to impart a water resistant adhesive strength capable of withstanding even in water. Therefore, in this example, the wood lignocellulosic pieces are immersed in an aqueous solution of magnesium, zinc, aluminum, iron chloride or sulfate, or these aqueous solutions are applied to the lignocellulosic pieces by a spray technique. A treatment is applied to attach the aqueous solution to the lignocellulosic pieces. Then, after drying the lignocellulose piece, polyvinyl alcohol (PVA),
A water-soluble polymer having a hydroxyl (OH) group such as starch,
It is immersed in a mixed aqueous solution with a water-soluble polymer having a carboxyl group. The immersion time has almost no effect, but there is no problem if it is set to about 30 seconds.

After immersion in this mixed aqueous solution,
Lignocellulosic pieces are pulled out of the aqueous solution and inserted into a mold which has been formed into a desired shape. The lignocellulosic pieces are then placed in a dryer with the mold described above and 10
A molded product having a specific gravity of 0.3 or less can be obtained by leaving it in an atmosphere of a temperature of 0 to 150 ° C. for 10 to 60 minutes. This low specific gravity lignocellulosic molded product has sufficient strength,
It showed water resistance enough to retain the shape even in water at 80 ° C. The mold may be made of punching metal or wire mesh, or a plastic net having a heat resistance of 120 to 150 ° C.

By the way, even if polyvinyl alcohol (PVA) or starch is used alone or in a mixture of both by the same method, a desired low specific gravity lignocellulose molded product cannot be obtained. Especially with polyvinyl alcohol (PVA),
Only extremely weak strength can be obtained, and starch has no water resistance. Further, even if a water-soluble polymer having a carboxyl group alone is used and the same method as described above is carried out, the desired low specific gravity lignocellulose molded product cannot be obtained. That is, in order to realize the low specific gravity lignocellulosic molded product according to the present invention, magnesium, zinc, aluminum, iron chloride, sulfate and polyvinyl alcohol (P
VA) or a water-soluble polymer having a hydroxyl (OH) group such as starch, and a water-soluble polymer having a carboxyl group are required to be combined. By using such a combination, For the first time, the desired low specific gravity lignocellulosic molded product can be obtained.

Magnesium, zinc used in this example,
The concentration of the aqueous solution of aluminum or iron chloride or sulfate is 0.1 to 5% by weight, and preferably 0.3 to 1.0% by weight. After treating the lignocellulose with this aqueous solution, it may be air-dried at room temperature or may be heated and dried. Examples of the polymer having a hydroxyl group (OH) include polyvinyl alcohol (PVA), polyvinyl acetate partial saponification products, polyvinyl alcohol (PVA) partial acetalization products, vinyl acetate copolymer partial saponification products, and the like. A starch derivative obtained by chemically modifying starch such as alcohol derivative, starch or oxidized starch is used. Further, as the polymer having a carboxyl group, polyacrylic acid, polyacrylic acid derivative, polymethacrylic acid, polymethacrylic acid derivative, isobutylene-maleic anhydride copolymer,
Isobutylene-maleic anhydride copolymer derivative, styrene-maleic anhydride copolymer derivative, styrene-maleic anhydride copolymer derivative, carboxymethyl cellulose (CM
C) and the like are preferably used. These polymers are used as an aqueous solution, and the total concentration of a mixed aqueous solution of a polymer having a hydroxyl (OH) group and a polymer having a carboxyl group may be 20% or less.

Next, a method for producing a low specific gravity lignocellulosic molded article according to the present invention will be described according to practical examples.
Of course, the present invention is not limited to the contents disclosed in this practical example. (Practical example 1) 15 g of a lignocellulose section (having a thickness of 0.5 to 2 mm and a length of 10 to 300 mm) obtained from a cypress was immersed in a 1% aqueous solution of sulfuric acid band, and then pulled up from the aqueous solution. Air dried. Next, the lignocellulosic pieces were mixed with polyvinyl alcohol (PVA) -117 (manufactured by Kuraray) 3%.
And 5% of isobutylene-maleic anhydride copolymer (Kuraray's "Isoban 110") mixed solution, and then inserted into a punching metal mold having a length of 100 mm, a width of 80 mm and a thickness of 10 mm. Then, it was dried in a dryer at a temperature atmosphere of 110 ° C. for 1 hour. The specific gravity of the obtained lignocellulose molded product was 0.18. This is immersed in 80 ° C. water for 5 minutes and then dried at 50 ° C. for 1 hour.
After immersing in water at 80 ° C. for 1 hour, the length swelling ratio, the width swelling ratio, and the thickness swelling ratio were measured. The measurement results of this low specific gravity lignocellulosic molded product showed that the length swelling ratio was 1.6%, the width swelling ratio was 0%, and the thickness swelling ratio was 76%, and the shape stability was sufficient.

As Comparative Example 1, the above-mentioned isobutylene-maleic anhydride copolymer (trade name "ISOBAN 11 manufactured by Kuraray Co., Ltd.
0 ") is not used, polyvinyl alcohol (PVA) -117
(Manufactured by Kuraray) The same procedure as in Example 1 was carried out using only a 3% aqueous solution. However, according to this Comparative Example 1, a low specific gravity lignocellulosic molded product having the intended content could not be obtained.

Further, Comparative Example 2 was carried out. That is, it was carried out in the same manner as in Example 1 except that polyvinyl alcohol (PVA) -117 was not used and only a 5% aqueous solution of an isobutylene-maleic anhydride copolymer (trademark "Isoban 110" manufactured by Kuraray) was used. However, also in this case, as in Comparative Example 1 above, a low specific gravity lignocellulose molded product having the intended content could not be obtained.

Practical Example 2 Lignocellulosic slices (thickness 0.5 to 1 mm, length 20 to 4) obtained from crushed cypress bark.
(0.5 mm), a 0.5% aqueous solution of ferrous sulfate was spray-coated and dried at 80 ° C. for 1 hour. Then, the lignocellulosic pieces were treated with polyvinyl alcohol (PVA) -105.
After immersing in a mixed aqueous solution of 3% (manufactured by Kuraray) and 3% of polyacrylic acid, molding was carried out by the same procedure as in actual example 1. The specific gravity of the obtained low specific gravity lignocellulosic molded product is 0.22.
When the molded product was immersed in water at 65 ° C. for 1 hour, the thickness swelling ratio was 85%, and the water resistance was sufficient.

Practical Example 3 Lignocellulosic slices (0.5-1 mm thick, 20-4 long) obtained from crushed bark of Japanese cypress.
15 g (0 mm) was immersed in a 1% aqueous solution of sulfuric acid band and then dried at 100 ° C. for 1 hour. Then, the lignocellulosic pieces were mixed with 10% oxidized starch and isobutylene-
Maleic anhydride copolymer (Kuraray's trademark "Isoban 11
0 ") 5% and then immersed in a mixed aqueous solution, and then molded in the same procedure as in practical example 1. The specific gravity of the obtained low specific gravity lignocellulosic molded product was 0.23, and the length swelling ratio, width swelling ratio and thickness swelling ratio when it was immersed in water at 60 to 80 ° C. for 1 hour were measured. Had a length swelling ratio of 0.4%, a width swelling ratio of 1.4%, and a thickness swelling ratio of 42%, and had sufficient water resistance. Further, the weight swelling ratio was 231%, which was not much different from the weight swelling ratio of 265% of the bark of the Japanese cypress, which was the raw material, and it was found that the water absorption was not impaired by the molding.

As Comparative Example 3, the molding was carried out in the same manner as in Example 3 except that the isobutylene-maleic anhydride copolymer (trade name "Isoban 110" manufactured by Kuraray Co., Ltd.) was not used and only a 10% aqueous solution of oxidized starch was used. However, the obtained molded product had no water resistance at all, and its shape collapsed rapidly when placed in water, so that it could not be put to practical use at all.

[0018]

As described above, according to the method for producing a low specific gravity lignocellulosic molded article according to the present invention, a lignocellulosic piece obtained from wood, for example, cutting scraps generated during wood processing, a back plate, a thinning material, By using a crushed material such as bark and waste material as a raw material and subjecting it to a heat treatment without pressurizing, a arbitrarily shaped lignocellulosic molded article having a specific gravity of 0.3 or less can be suitably produced. Also, the manufactured low specific gravity lignocellulosic molded product can be obtained in any shape without using a hot press machine, so that the manufacturing cost becomes low and, for example, a separation material such as a lignocellulosic filter or a strainer, It can be used as a filtering material and an absorbing material. This type of separation material, filtration material, and absorption material are easy to handle, and since they can be incinerated after use, they do not pollute the environment, and they have excellent advantages such as effective utilization of combustion heat. is doing.

Claims (4)

[Claims] 1. A water-soluble polymer having a hydroxyl group, which is made of strip-shaped lignocellulose that does not entangle with each other, is treated with an aqueous solution of magnesium chloride, zinc chloride, aluminum chloride, iron chloride or sulfate, and is then dried. It is dipped in a mixed aqueous solution with a water-soluble polymer having a carboxyl group, and is further heat-dried in a temperature range of 80 to 180 ° C. in a required mold, and has a specific gravity of 0.3 or less. Also, a low specific gravity lignocellulosic molded product that exhibits stable shape retention in water at 50 ° C. 2. A strip-shaped lignocellulose which is not entangled with each other is treated with an aqueous solution of a chloride or sulfate of magnesium, zinc, aluminum, iron, and then dried to obtain the strip-shaped lignocellulose, After immersing in a mixed aqueous solution of a water-soluble polymer having a hydroxyl group and a water-soluble polymer having a carboxyl group, this is taken out, and the strip-shaped lignocellulose is inserted into a required mold and shaped. The method for producing a low specific gravity lignocellulosic molded product is characterized in that it is dried by heating within a temperature range of 80 to 180 ° C. 3. The method for producing a low specific gravity lignocellulose molded product according to claim 2, wherein polyvinyl alcohol or a derivative thereof is used as the water-soluble polymer having a hydroxyl group. 4. The method for producing a low specific gravity lignocellulose molded product according to claim 2, wherein starch or a derivative thereof is used as the water-soluble polymer having a hydroxyl group.