JP2003285305A - Novel fiberboard and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To develop a fiberboard made of lignin so that the lignin not used so far as a lumber resource is effectively utilized. <P>SOLUTION: The fiberboard utilizing the lignin and a fibrous substance as raw materials, and its manufacturing method are provided. The lignin as the raw material is a lumber resource which has not been effectively utilized so far, and the fiberboard provides a new use of the lignin. The fiberboard is also strong because of its high flexural strength, and meets the JIS hardboard standard (S35). The manufacturing method is also improved, that is, the fiberboard is improved in its strength since the fiber is dried at a high temperature. A wet process developed in this invention is simpler than a conventional dry process, and the fiberboard manufactured with the wet process shows a more improved performance than that manufactured with the dry process. The strength of the fiberboard is further improved by adding a high-molecular substance such as a biodegradable polyester resin. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a fiberboard using lignin, which is an unused wood resource, as a raw material, and a method for producing the fiberboard.

[0002]

2. Description of the Related Art Low-quality broad-leaved trees are cultivated as environmental forests because of their public mission such as conservation and maintenance of the global environment.
Also, in the industry using wood, a lot of low-quality wood-based waste is generated in the manufacturing process of products. Establishing a technology that can use many of these low-quality trees and wood-based wastes as organic resources (biomass) is important from the standpoints of improving the global environment and effectively using organic resources.

Under such circumstances, the inventors of the present invention are conducting research for the effective use of lignin derived from low quality trees such as hippopotamus from the viewpoint of using low quality trees. Various studies have been made so far on the effective use of lignin, but in terms of utilization as a raw material for wood board (fiber board), which is expected to be much demanded as furniture members and building materials, no previous studies have been made. It wasn't enough.

Conventional wooden boards have been manufactured using wood fibers and construction waste as raw materials and synthetic polymers as adhesives. The so-called "sick house syndrome", which is caused by the release of chemical substances represented by formaldehyde from building materials, has become a social problem, and the conventional wood board has been a cause for that. In addition, because of incomplete biodegradation, there was a problem of disposal due to it.

[0005]

Therefore, by providing a fiber board using lignin as a raw material, it is possible to provide a fiber board that compensates for the drawbacks of the conventional wood-based boards.
Further, it is an object of the present invention to make effective use of lignin thereby.

[0006]

A first aspect of the present invention is a fiberboard characterized by containing a mixture of lignin and pulp fibers. In the fiberboard, the content of lignin is 5 to 60%, the lignin is a fusible lignin selected from the group consisting of acetate lignin, HBS lignin and organosolv lignin, or a group consisting of kraft lignin and lignin sulfonic acid. It is a more selected industrial lignin.

Another aspect of the present invention is a method for producing a fiber board, which comprises defibrating a fibrous substance, heating and drying the defibrated fibrous substance at a temperature of 100 to 200 ° C. A step of preparing a mixture of the fiber raw material and lignin and molding the mixture by hot pressing at a pressing pressure of 60 to 400 kgf / cm ² at a temperature of 130 to 250 ° C.
It is a manufacturing method of a fiberboard. Further, a further aspect of the present invention is a method for producing a fiber board, which comprises defibrating a fibrous substance,
Prepare a mixture of the defibrated fibrous substance and lignin,
A method for producing a fiber board, which comprises a step of molding the mixture by hot pressing at a temperature of 150 to 250 ° C. and a pressing pressure of 150 to 350 kgf / cm ² .

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In order to solve the above problems, for the purpose of recycling newspaper and magazine waste paper from forestry waste and effectively utilizing lignin, which is an unused wood component, high strength wood from a mixture of the two is used. We have developed a system board (fiber board) and a simple method for making the fiber board. The fiberboard of the present invention is
It can be used as a furniture member or building material in the woodworking field and the construction field, and can also be used as a disposable tray in the field of packaging daily necessities.

The lignin used as a raw material in the present invention is a natural polymer which is present in a large amount, but it has only been used as a fuel until now. Since lignin isolated by the solvent pulping method exhibits heat-melting property, it was expected to function as a hot-melt type adhesive. Therefore, in the present invention, lignin was mixed with newspapers, magazines, and the like, and an attempt was made to produce a fiber board without using a conventionally used adhesive. As a result, a board having sufficient strength was obtained as shown in the following examples. Furthermore, water resistance was strengthened by improving the process, and a hard board satisfying JIS A5905 S35 was manufactured. This board does not have a sick house concern because it does not require the formaldehyde-derived adhesive used in conventional fiberboard manufacturing. Since lignin is a hydrophobic material, it also contributes to the reduction of water absorption. Furthermore, since it has already been confirmed that the biodegradability, which is a characteristic of a natural product raw material, is retained, it is an environmentally friendly fiberboard.

Lignin, as used herein, is a natural polymeric substance that acts to strengthen trees.
Lignin is not only a natural polymer that is most abundant next to cellulose, but also one of the most abundant organic substances on the earth in terms of the amount of immobilized energy. There is also a problem that a large amount of existing lignin is hard to be decomposed, and thus far it has been considered as a component having no utility value and discarded, and its effective utilization is an important problem.

The woody raw material of lignin used in the present invention is not particularly limited, such as conifers and hardwoods,
It is preferable to use agricultural waste. As described above, it is preferable to use the meltable lignin for the sake of functioning as a hot melt type adhesive. As such a suitable meltable lignin, lignin acetate,
HBS lignin and organosolv lignin can be mentioned. Further, general industrial lignin such as kraft lignin and lignin sulfonic acid can also be used for the purpose of the present invention, and the lignin used is not particularly limited. Among these various lignins, it is particularly preferable to use acetic acid lignin, HBS lignin and organosolv lignin.

An atmospheric pressure acetic acid pulping method is known as a method for preparing lignin acetate. Specifically, lignin acetate can be obtained from a cooking liquor obtained by digesting these wood raw material chips with atmospheric pressure acetic acid. An example of the production method is as follows. Chips are extracted by boiling with 90 to 95% acetic acid water and mineral acids such as hydrochloric acid or sulfuric acid, the obtained extract is concentrated under reduced pressure, and sugars are removed by fractional precipitation with water. Is. The preparation and use of lignin acetate are described in, for example, Proceedings of the Hokkaido Section of the Wood Research Society of Japan, Vol. 26, October 1994, pages 67 to 70. Further, Japanese Patent Application Laid-Open No. 11-12971 discloses an acetic acid pulping using straws.

HBS lignin can be obtained by pulping with a high boiling organic solvent (HBS pulping).
180 by mixing pulp raw material with high boiling organic solvent such as 1,4-butanediol (BDOL) and propylene glycol (PG)
The HBS pulping method is carried out by treating at a high temperature of ~ 230 ° C. The method of pulping with a high boiling point organic solvent is
It is disclosed in Japanese Patent Laid-Open No. 2001-89986.

In the following examples, HAL (Hardwood Acet) prepared from white birch was used as the lignin acetate.
ic acid Lignin), SAL (Softwo
od Acetic acid Lignin), and as HBS lignin,
HBL (Hardwood BDO) prepared from birch using BDOL
L Lignin) and HPL prepared using PG (Hardwood
PG Lignin). As a result of the examination,
All of these lignins were suitable as raw materials for the fiberboard of the present invention, and HAL and SAL were particularly suitable.

As the fibrous substance mixed with lignin,
Fibers of various origins such as pulp fibers and recycled cellulose can be used, and the concept of fibrous material in the present specification is not to be construed in a limited manner. Among them, from the viewpoint of effective utilization of forestry waste, it is particularly preferable to use used newspapers, magazines, cardboards and the like. However, it is naturally possible to carry out the present invention by using virgin pulp not derived from waste paper, and such an embodiment is also within the scope of the present invention. In the examples below,
A study was carried out using newspaper wastepaper, magazine wastepaper, cardboard wastepaper, copy paper wastepaper, birch pulp, and todomatsu pulp, and favorable results were obtained in all cases.
The lignin content is in the range of 5 to 60%, preferably 10 to 40%, more preferably 15 to 30%. As shown in the examples below, the fiber board of the present invention showed the highest bending strength when the content of HAL which is lignin was about 20%.

As a process of a dry method which is a method for producing a fiber board using dried fibers, crushed pulp fibers are air-dried at room temperature for about 3 days, and then lignin is added to perform hot pressing. Conventionally, the process of forming a board by doing so has been adopted. In the present invention, an attempt was made to improve this dry method. That is, when the pulp fiber was dried in a high temperature oven instead of air drying, the bending strength was clearly improved. The conventional method and the modification method adopted in the present invention are shown in FIG. It is necessary to form hydrogen bonds between fibers to increase the strength of the board, but it is believed that hydrogen bonding is formed by drying in an oven, which improves the strength of the fiberboard. Be done.

The drying temperature of the fibrous material in the modified dry method is 100 to 200 ° C, preferably 100 to 15 ° C.
The temperature is 0 ° C, and more preferably 100 to 120 ° C. Considering the above-mentioned formation of hydrogen bonds, the conditions of hot pressing are also important in the dry method. Hot press is 130 ~
It is carried out at a temperature of 250 ° C, preferably 140 to 200 ° C, more preferably 150 to 180 ° C. The pressing pressure of the hot press is 60 to 400 kgf / cm ² , preferably 110 to 350 kgf / cm ² , and more preferably 120 to 300 kgf / cm ² .
It is cm ² . It is within the scope of ordinary contrivances of those skilled in the art to appropriately select the optimum conditions from these conditions, and the fiber board of the present invention can be produced in various modes.

Further, in the present invention, the manufacturing process of the wet board was also examined and the process by the wet method was established. The wet method is a method in which defibrated pulp fibers are mixed with lignin without being dried and hot-pressed.Since the pulp fiber drying step is omitted, it is a simpler method than the dry method. . A flowchart of the dry method and the wet method is shown in FIG. When the performance of the fiberboard manufactured by the wet method was examined, it was superior in strength and water absorption to the dry board manufactured by the dry method.

In the wet method, the conditions are particularly important in order to form hydrogen bonds between fibers mainly by hot pressing. Hot pressing is carried out at a temperature of 150 to 250 ° C, preferably 160 to 250 ° C, more preferably 170 to 250 ° C.
It is carried out at a temperature of ~ 200 ° C. The pressing pressure of the hot press is 150 to 350 kgf / cm ² , preferably 200 to 330.
kgf / cm ² , more preferably 250 to 300 kgf / cm ² .
It is within the scope of ordinary contrivances of those skilled in the art to appropriately select the optimum conditions from these conditions, and the fiber board of the present invention can be produced in various modes.

The fiber board of the present invention has high biodegradability. BOD (biolog of fiberboard manufactured by wet method
The BOD was higher than that of the blank test when the ical oxygen demand) was measured. Since the biodegradability is high and the raw material is waste, the fiberboard of the present invention is not only excellent in physical properties such as strength, but also an environment-friendly new-generation fiberboard. Can be said. Considering that the protection of the global environment has become a major social problem at present, the fiber board of the present invention is considered to be of great significance.

By adding a polymer substance such as a biodegradable polyester resin or a phenol resin, it is possible to further increase the strength and reduce the water absorption. Preferred biodegradable polyester resins include, but are not limited to, polybutylene succinate, polyethylene succinate, polyhydroxyalkanoate, and polycaprolactone. In the following examples, the effects of addition of a mixed resin of polybutylene succinate and polyethylene succinate (trade name: Bionole) on flexural strength and water absorption are examined. However, the addition of bionore flexural strength and water absorption. Both rates have improved.

[0022]

EXAMPLES (Production of Board by Dry Method) A board was produced by the dry method by the production process shown in the correction method on the right side of FIG. Dissolve used newspapers and magazines in water to 105 ℃
Dried at a temperature of. After mixing a predetermined lignin with this, it put in a cylindrical (10 cmφ) molding machine and changed the temperature and pressure to perform hot pressure molding for 15 minutes to prepare a fiber board.

(Production of Board by Wet Method) A board of the wet method was produced by the production process shown on the right side of FIG. Suspended newspapers and magazines in water, added lignin and stirred, then suction-filtered and kept in a rectangular shape (5c
m X 20 cm) shaper put 180 ° C., and 2 at 270 kgf / cm ²
Pressed for hours.

(Physical Property Test) 1. Bending strength test All boards were measured for strength according to JIS K6911. Wet boards were also measured according to JIS A5905, a fiberboard standard. 2. According to the water absorption test JIS A5905, the weight increase rate after immersion after 24 hours was shown as a percentage.

(Effects of Various Factors on Bending Strength of Board Prepared by Dry Method) In the dry method, from a sample of 30 g,
A hard board having a thickness of about 3 mm and a density of 1.2 to 1.4 g / cm ³ was obtained. The specific gravity of this board is 1g / cm ³ or more, and it is classified as a JIS hard board. Fig. 3 shows the results of comparing the bending strengths of the dry board made by the conventional method and the dry board made by the modified method that was oven-dried at various lignin (lignin: HAL) derived from white birch. Indicates. As a result, at any HAL content, the dry board produced by this modified method showed stronger strength than that by the conventional method. And, the highest bending strength at a HAL content of 20%,
Its value is 67MP, which is about twice that of JIS hardboard standard S35.
It was a.

FIG. 4 shows the results of examining the influence of the press pressure on the bending strength at various HAL contents. 230k
When the press pressures of gf / cm ² and 345 kgf / cm ² were examined, no difference was observed between the two, and at any press pressure, a high bending strength value of 60 MPa or more was shown at a HAL content of 20%. .

The effect of press pressure and temperature on the bending strength was examined under a fixed amount of lignin. 130 ℃ to 20
115kgf / cm ² , 230kgf / cm ² , 345k under the temperature range of 0 ℃
High bending strength was measured by molding with a press pressure of gf / cm ² (Fig. 5). At the pressing pressures of 230kgf / cm ² and 345kgf / cm ² , bending strength was higher at the melting temperature (170 ° C) than at the glass transition temperature (130 ° C) of HAL. The optimum melting temperature was the molding temperature, indicating that HAL functions as a hot-melt adhesive.

(Effects of Various Factors on Water Absorption Rate of Board Prepared by Dry Method) The water absorption rate at various HAL contents was examined (FIG. 6). Although the water absorption rate of the board made of only waste paper was extremely high, a remarkable decrease in the water absorption rate was observed only by adding 10% of lignin. In addition, the influence of press pressure and temperature on the water absorption rate was examined (Fig. 7). As a result, at any pressing pressure, the water absorption rate decreased as the press temperature increased, and the water absorption rate of the board pressed at 170 ° C or higher was 30% or less.

(Study of various lignin raw materials) Dry boards were prepared using various lignin raw materials, and their bending strength and water absorption were measured. As a lignin, HAL
20% (S), SAL 20% (A), HPL 20% (B), HBL 20% (C)
, KL (craft lignin) 20% (D), LS (lignin sulfonate) 20% (E), HAL 17% + PH (phenolic resin) 3% (F), HAL 15% + PH 5% (G) , PH 20% (H) was used. Molded with a press pressure of 230 kgf / cm ² using fibers derived from waste newspaper. The results of bending strength are shown in FIG. 8 and the results of water absorption are shown in FIG. When any lignin was used, it showed high strength and had good properties as a fiberboard.

(Study of various fiber raw materials) Dry boards were prepared using various fiber raw materials, and their bending strength and water absorption were measured. As the fiber raw material, recycled newspaper (S),
Magazine waste paper (I), birch pulp (J), Todomatsu pulp
(K), cardboard waste paper (L), copy waste paper (M) and newspaper waste paper (N) were used. 230kgf / c using 20% HAL lignin
It was molded at a pressing pressure of m ² and a pressing temperature of 170 ° C. The results of bending strength are shown in FIG. 10, and the results of water absorption are shown in FIG. When any fiber was used, it showed high strength and had good properties as a fiber board.

(Study of Physical Properties of Wet Board) Physical properties of a board manufactured by a wet method were examined. Various lignins (HA
L) Fig. 12 shows the results of examination of bending strength in terms of content rate.
13 shows the results of examining the water absorption rate. Wet board strength is increased compared to dry board, lignin content 30%
At that time, the maximum was 96 MPa. In addition, the water absorption rate was also greatly reduced to 13%, and it was possible to produce a highly practical fiber board that sufficiently satisfied the JIS standard of 35%.

In this study, the effect of adding a biodegradable polyester resin was examined in order to further increase the strength and reduce the water absorption. As biodegradable polyester resin, mixed resin of polybutylene succinate and polyethylene succinate (Brand name: Bionore)
It was used. As a result, it was shown that bionole is effective for improving the strength of wet boards and reducing the water absorption.

(Study on biodegradability of wet board) Further, the biodegradability of the prepared wet board was measured by BOD (biological ox).
ygen demand) was used as an index (Fig. 14). 14
From the biodegradation test of wet board containing 20% HAL
The BOD value was higher than that of the blank test, indicating the expected high biodegradability.

[0034]

Industrial Applicability According to the present invention, there are provided a fiberboard using lignin and a fibrous material as raw materials, and a method for producing the fiberboard. Lignin, which is a raw material, is a wood resource that has not been effectively used until now, and the fiber board of the present invention provides a new utilization method of lignin. Further, the fiber board of the present invention was strong because of its high bending strength, had low water absorption, and satisfied the JIS hardboard standard (S35).
The manufacturing method was also improved, and the strength of the fiberboard was improved by drying the fiber at high temperature. In addition, the wet method developed in the present invention is simpler than the conventional dry method, and the performance of the fiberboard produced by the wet method is improved as compared with that produced by the dry method. Moreover, the strength of the fiberboard was further improved by adding a polymer substance such as a biodegradable polyester resin.

[Brief description of drawings]

FIG. 1 is a schematic diagram comparing the steps of a conventional method for producing a dry board and a modification method of the present invention.

FIG. 2 is a schematic diagram comparing a dry method step and a wet method step.

FIG. 3 is a graph showing flexural strengths of fiberboards manufactured by a conventional method and a modified method at various amounts of lignin (dry method).

FIG. 4 is a graph showing the effect of pressing pressure on bending strength at various amounts of lignin (dry method).

FIG. 5 is a graph showing the influence of the press pressure and the press temperature on the bending strength at a constant lignin amount (dry method).

FIG. 6 is a graph showing the effect of a change in the amount of lignin on the water absorption rate (dry method).

FIG. 7 is a graph showing the effect of press pressure and press temperature on water absorption (dry method).

FIG. 8 is a graph showing flexural strength measured on fiberboards produced using various lignin raw materials (dry method).

[Fig. 9] Fig. 9 is a graph showing the water absorption measured on fiberboards prepared by using various lignin raw materials (dry method).

FIG. 10 is a graph showing flexural strength measured on fiber boards produced using various fiber raw materials (dry method).

FIG. 11 is a graph showing the water absorption measured in fiber boards produced using various fiber raw materials (dry method).

FIG. 12 is a graph showing the influence of the amount of lignin on the bending strength of a fiberboard produced by the wet method (wet method).

FIG. 13 is a graph showing the influence of the amount of lignin on the water absorption of a fiberboard produced by the wet method (wet method).

FIG. 14 is a BOD of a fiberboard produced by a wet method.
It is the graph which showed the value.

Claims (9)

[Claims] 1. A fiberboard comprising a mixture of lignin and a fibrous material. 2. The lignin content is 5 to 60%,
The fiber board according to claim 1. 3. The fiber board according to claim 1, further comprising a biodegradable polyester resin or a phenol resin. 4. The fiber board according to claim 3, wherein the biodegradable polyester resin is polybutylene succinate, polyethylene succinate, polyhydroxyalkanoate, or polycaprolactone. 5. The lignin is a fusible lignin selected from the group consisting of acetate lignin, HBS lignin and organosolv lignin, or industrial lignin selected from the group consisting of kraft lignin and lignin sulfonic acid. The fiber board according to 1. 6. The fiberboard according to claim 1, wherein the fibrous substance is pulp fiber. 7. The fiber board according to claim 6, wherein the pulp fibers are pulp fibers derived from waste paper. 8. A method for producing a fiber board, which comprises defibrating a fibrous substance, heating and drying the defibrated fibrous substance at a temperature of 100 to 200 ° C. to prepare a fiber raw material, And a lignin, and a method of producing a fiber board, which comprises a step of hot pressing and molding the mixture at a temperature of 130 to 250 ° C. and a pressing pressure of 60 to 400 kgf / cm ² . 9. A method for producing a fiber board, which comprises defibrating a fibrous substance, preparing a mixture of the defibrated fibrous substance and lignin, and mixing the mixture at a temperature of 150 to 250 ° C. for 150 to 250 ° C. 350 k
A method for producing a fiberboard, which comprises a step of forming by hot pressing under a press pressure of gf / cm ² .