JPH0693001A - Benzylated molding material of lignocellulose and its production - Google Patents

Abstract

PURPOSE:To obtain a raw material capable of developing both performances of a raw material and a plastic using lignocelluloses as raw materials. CONSTITUTION:A benzylated molding material of lignocellulose produced by pretreating a wood having a fiber form or a chip consisting of lignocelluloses such as bamboos with an aqueous solution of sodium hydroxide and then treating the pretreated wood material or chip with benzyl chloride or a mixed liquid of benzyl chloride and xylene by a liquid phase or vapor phase method, forming and thermally compacting the treated material under pressure to cause thermal fusion of chip surface and its production.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lignocellulosic material such as wood and bamboo, that is, a novel plant-based molding material obtained from a plant raw material having a fiber containing lignin and cellulose. The present invention relates to a wood-based material that maintains the unique characteristics and has the performance of plastics.

[0002]

2. Description of the Related Art So-called plant materials such as wood and bamboo are
It has been used in many fields since ancient times because it is easy to obtain and process, its elegant texture, warm feeling and appearance, unique color tone, and the fact that it is possible to reproduce the raw materials by planting. . Today, in order to make more effective use of wood resources and the like, waste wood and small-diameter wood that cannot be used as lumber are molded and used as particle boards or fiber boards. Among these, particle boards are made by crushing wood or the like into chips whose unit size is larger than fibers of wood or the like, and thermosetting adhesives (phenol formaldehyde resin, A urea formaldehyde resin, a water-based vinyl urethane resin, etc.) is sprayed as a binder and is molded and solidified into a predetermined shape by hot pressing.

On the other hand, the fiberboard has the above-mentioned party.
Use wood fibers, which are smaller than the chips used for the clouboard, and spray them with a binder to heat-press them, and dry-board to disperse the fibers in water and deposit them on a net like a paper strainer. There are two types of wet boards. Furthermore, as one of the technologies for effectively utilizing wood resources, a technology has also been proposed in which wood waste materials that have no fiber form are made into plastics and used as substitutes for general-purpose plastic products. The plasticization of wood in this technology is
This is based on a conventionally known method for producing benzyl cellulose. These wood-based materials are extremely important for effective use of forest resources.

[0004]

However, wood,
While wood-based materials such as bamboo, particle board, fiber board, and plasticized wood as described above have advantages, they have various problems that need to be solved. For example, in a particle board, since the bonding between the chips is point bonding with an adhesive, the bonding force between the chips is small, and the dimensional change particularly in the thickness direction becomes very large. In addition, low water resistance is also a big problem. That is, such a particle board swells significantly when it comes into contact with water, and thus its strength is significantly reduced.

Further, there is also a problem that it easily decays in a hot and humid environment, and therefore its use is extremely limited. Fiberboard has some moldability because it uses fibers, but loses the color tone and grain peculiar to wood, is poor in texture, and easily undergoes dimensional changes and decay. In particular, in the manufacture of particle boards, a step of spraying a thermosetting adhesive onto the chips before forming the chips and then heat-pressing and forming into boards after forming is required. It accounts for a large proportion of the manufacturing cost.

[0006] Further, wood, bamboo and the like undergo dimensional change and decay, and since they do not have the thermoplasticity of plastics and metal materials, they are inferior in moldability and have limited applications while having excellent performance. The reality is that we have not been able to fully realize the effective use of. In addition, the above wood plastic
The performance is no different from that of ordinary general-purpose plastics, and there is the problem that the color tone, grain, moisture absorption and release, warm texture, etc. peculiar to the raw material wood are lost.

[0007]

According to the present invention, chips made of lignocellulosics such as wood and bamboo having a fiber form are pretreated with an aqueous sodium hydroxide solution, and benzyl chloride alone or a mixture of benzyl chloride and xylene is mixed. After replacing the hydroxyl groups in the chips with benzyl groups by treating with liquid in a liquid phase or vapor phase method, each treated chip is formed and heat-pressed, and the heat fusion action between the chip surfaces causes the raw material It is an object of the present invention to solve the above-mentioned conventional problems by producing a molding material having the characteristics of both lignocelluloses and plastics. In the present invention, the degree of benzyl etherification of the chip is adjusted by changing the reaction time, reaction temperature, etc. in the benzyl etherification step of the chip, and a molding material having more performance of the raw material lignocellulose, or the reverse It is possible to arbitrarily obtain a molding material in which the performance of plastics has been revealed. The raw material of the present invention is a plant material containing lignin such as wood, bamboo, sugar cane bagasse, rubber tree waste material, oil palm waste material, rice straw, and straw, and cellulose.

[0008]

[Function] When a lignocellulosic chip is benzyl etherified, the hydroxyl group in the chip is replaced with a benzyl group having a large molecular weight and being hydrophobic and having a small polarity, whereby the crystalline region of the cellulose is made amorphous so that the cellulose Thermoplasticity is improved. Furthermore, hemicellulose and lignin, which themselves have thermoplasticity, are also made into substances with extremely high thermoplasticity by being benzyl etherified, and these act as internal plasticizers, so that wood chips etc. as a whole have thermal melting properties. become. Further, the benzyl group has a large molecular weight and has a benzene skeleton at the end thereof, so that it is easy for molecular movement, and thus it is considered to have high heat melting property. Therefore, the bonding force between the chips is strengthened by the heat-sealing action,
Good dimensional stability can be obtained.

In addition, since the hydrophilic hydroxyl group is replaced with the hydrophobic benzyl group in the chip, the water resistance of the molding material is greatly improved, and problems such as swelling due to contact with water are corrected. . Furthermore, since the chemical structure of lignocelluloses is changed by the benzyl ether formation, the decomposing ability of the decay fungal enzyme does not work, and the molding material exhibits high decay resistance.

Generally, when etherification of lignocelluloses is carried out, the reaction does not proceed unless these are converted into sodium salt form. Therefore, in the present invention, pretreatment with sodium hydroxide is performed. The chemical formulas showing the action of the present invention described above are shown below as Chemical Formula 1 and Chemical Formula 2 using wood as an example. Pretreatment with sodium hydroxide

[0011]

[Chemical 1]

Benzyl etherification

[Chemical 2]

[0013]

Embodiments of the present invention will be described below. Example 1: a. 50 g of dried red pine chips with a fiber direction of 10 to 20 mm, a width direction of 5 to 15 mm and a thickness of 0.1 to 0.5 mm
Immerse in 0% sodium hydroxide at room temperature for 2 hours. b. After immersion, press to remove excess sodium hydroxide aqueous solution, put 1 liter of benzyl chloride into a 3 liter separable flask equipped with a reflux condenser, and cool to 105 ° C.
The temperature is maintained at 1, and the red pine chips are put in this and reacted for 1 hour. c. After the reaction, the excess reaction solution is removed by squeezing and washed in running water for 24 hours. After this water washing, immersion washing in a water-methanol (1: 1 v / v) solution is performed for 24 hours,
After air-drying for 48 hours, vacuum drying at 40 ° C for 24 hours,
Benzyl etherified red pine chips are prepared. In addition,
Due to the volume of the flask, the above operation is repeated several times to prepare a predetermined amount of benzyl etherified chips. d. The prepared chip is put in the forming box as it is, and the target size is 250 mm × 250 mm × 4 mm.
Then, in order to obtain three types of boards (molding materials) with target specific dry densities of 0.6, 0.8, and 1.0, respectively, the chips were formed, and the chips were formed at 150 ° C. and 20 kg / c for 10 minutes. Heat press for minutes. Thus, in this example, three types of boards (molding materials) having a benzylation degree (weight increase rate of chips) of 21% and different target absolute dry gravities as described above were obtained. In each of these boards, the grain of the chips can be seen and the wood tone is left, while the surface exhibits high gloss and smoothness.

Example 2: a. 50 g of dried red pine chips with a fiber direction of 10 to 20 mm, a width direction of 5 to 15 mm and a thickness of 0.1 to 0.5 mm
Immerse in 0% sodium hydroxide at room temperature for 2 hours. b. After immersion, press to remove excess sodium hydroxide aqueous solution, put 1 liter of benzyl chloride into a 3 liter separable flask equipped with a reflux condenser, and store at 110 ° C.
The temperature is maintained at 1, and the red pine chips are put in this and reacted for 1 hour. c. After the reaction, the excess reaction solution is removed by squeezing and washed in running water for 24 hours. After this water washing, immersion washing in a water-methanol (1: 1 v / v) solution is performed for 24 hours,
After air-drying for 48 hours, vacuum drying at 40 ° C for 24 hours,
Benzyl etherified red pine chips are prepared. In addition,
Due to the volume of the flask, the above operation is repeated several times to prepare a predetermined amount of benzyl etherified chips. d. The prepared chip is put in the forming box as it is, and the target size is 250 mm × 250 mm × 4 mm.
Then, in order to obtain three types of boards (molding materials) with target specific dry densities of 0.6, 0.8, and 1.0, respectively, the chips were formed, and the chips were formed at 150 ° C. and 20 kg / c for 10 minutes. Heat press for minutes. Thus, in this example, three types of boards (molding materials) having a degree of benzylation (weight increase rate of chips) of 38% and different target absolute dry gravities as described above were obtained. In each of these boards, the grain of the chips can be seen and the wood tone is left, while the surface exhibits high gloss and smoothness.

Example 3: a. 50 g of dried red pine chips with a fiber direction of 10 to 20 mm, a width direction of 5 to 15 mm and a thickness of 0.1 to 0.5 mm
Immerse in 0% sodium hydroxide at room temperature for 2 hours. b. After immersion, press to remove excess sodium hydroxide aqueous solution, put 1 liter of benzyl chloride into a 3 liter separable flask equipped with a reflux condenser, and keep at 120 ° C.
The temperature is maintained at 1, and the red pine chips are put in this and reacted for 1 hour. c. After the reaction, the excess reaction solution is removed by squeezing and washed in running water for 24 hours. After this water washing, immersion washing in a water-methanol (1: 1 v / v) solution is performed for 24 hours,
After air-drying for 48 hours, vacuum drying at 40 ° C for 24 hours,
Benzyl etherified red pine chips are prepared. In addition,
Due to the volume of the flask, the above operation is repeated several times to prepare a predetermined amount of benzyl etherified chips. d. The prepared chip is put in the forming box as it is, and the target size is 250 mm × 250 mm × 4 mm.
Then, in order to obtain three types of boards (molding materials) with target specific dry densities of 0.6, 0.8, and 1.0, respectively, the chips were formed, and the chips were formed at 150 ° C. and 20 kg / c for 10 minutes. Heat press for minutes. In this way, in this example, three types of boards (molding materials) having a degree of benzylation (weight increase rate of chips) of 51% and different target absolute dry gravities as described above were obtained. In each of these boards, the grain of the chips can be seen and the wood tone is left, while the surface exhibits high gloss and smoothness. In each of the above examples, the liquid phase method was adopted in the benzyl etherification step, but it goes without saying that a gas phase method may also be used. In this case, the reaction vessel is partitioned into two chambers with a net or the like, a reaction solution which is benzyl chloride or a mixed solution of benzyl chloride and xylene in an arbitrary ratio is put, and the pretreated lignocelluloses are placed on the net. It is placed and reacted at a predetermined temperature for a predetermined time.

In each of the examples, the wood used had a chip-like size having a tissue structure. This is because the fibrous layer remains in the non-benzylated portion and maintains the unique performance of the wood. Next, the properties of the board (molding material) obtained in each of the above examples will be described with reference to the diagrams shown in the accompanying drawings.

FIG. 1 shows the board according to each of the above-mentioned embodiments and the particle board according to the prior art (resin ratio 10%: ratio of binder to dry chips) in water at 25.degree.
It is a graph which shows the swelling rate of thickness in the experiment immersed for time. Each board has an absolute dry specific gravity of around 0.6,
Three types were used, one around 0.8 and one around 1. In the figure, PF is the conventional board, and WPG is the benzylation degree (weight increase rate of the chip) of the board according to each example. From the graph of FIG. 1 showing the experimental results, it is found that the dimensional stability of the board (molding material) having a high degree of benzylation and a large specific gravity is improved. That is, the thickness (swelling rate) of the board (molding material) having a WPG (degree of benzylation) of 51% and a specific gravity of about 1.0 is 1% or less,
This value is 1/20 or less of the board PF according to the prior art, and it can be seen that very excellent dimensional stability is exhibited.

FIG. 2 relates to each of the above embodiments, and a board prepared from three types of chips each having a different degree of benzylation and a particle board according to the prior art (resin ratio 10).
%) Is a graph showing the results of examining the bending strength of each board at a predetermined specific gravity. In the figure, P
F is the conventional board, and WPG is the benzylation degree (chip weight increase rate) of the board according to each example. Each of the boards according to the examples shows a numerical value that is about 20% lower than that of a conventional board, but those having a specific gravity of 0.8 or more have a numerical value of 20 MPa or more, which is a practically sufficient strength. Shows.

FIG. 3 relates to each of the above-mentioned examples, and a board prepared from three types of chips having different degrees of benzylation and a particle board according to the prior art (resin ratio: 10).
%) Is a graph showing the results of examining the internal bond strength of each board at a predetermined specific gravity. In the figure, PF is a conventional board and WPG is a board according to each embodiment.
3 shows the degree of benzylation (degree of increase in chip weight). This shows that the internal bond strength increases in proportion to the benzylation degree of the chip and the specific gravity of the board. The internal bond strength of a board with WPG 51% and a specific gravity of about 1 is about twice as high as that of the conventional board, which is one of the drawbacks of the conventional particle board. Has significantly improved strength.

FIG. 4 is a graph showing the experimental results for verifying the thermal softening property of benzyl etherified lignocelluloses according to the present invention. In this experiment, red pine wood flour (about 16 mesh) was used as a raw material, and the above-mentioned Example a,
Under the same conditions as in b and c, three kinds of benzyl etherified wood flour, namely WPG (degree of benzylation) of 27%, 31% and 37% were prepared (wood flour of about 16 mesh was benzyl etherified), The thermal softening properties of these and untreated wood flour were measured under a predetermined temperature condition. The measurement method is the penetration method, that is, each of the wood powders to be tested is packed in a small container, and a quartz needle with a load (25 g) is applied onto the small container, and the needle enters when the temperature is changed. It depends on the method of measuring the degree. In addition,
In the figure, WPG indicates the degree of benzylation. From this experiment, untreated wood flour has only about 30% penetration even at 300 ° C, which is higher than the thermal decomposition point of wood components, and does not heat-melt, whereas benzyl etherified wood flour starts at around 90 ° C. It can be seen that the higher the degree of benzylation, the more it shows the heat softening property, the more remarkable it becomes as the temperature rises, and that all the benzyl etherified wood flour is melted by 300 ° C.

FIG. 5 shows W obtained in the above-mentioned Examples a, b and c.
PG (degree of benzylation) is 21%, 38%, 51 respectively
3 different benzyl etherified chips were produced,
It is a graph which shows the experimental result which prepared these into about 16 mesh wood flour, and examined the heat melting property of each wood flour by the penetration method similar to the case of FIG. In general, the heat melting property is lower than in the case of benzylating wood flour as shown in FIG. 4, but this is lower in the case of benzylated chips as wood flour in FIG. This is because some of the wood chips are mixed into wood powder, and the chip surface has the same heat melting property as the wood powder shown in FIG.

Next, the results of the decay test of the molding material according to the present invention are shown in Table 1 below. In this test, the three types of boards according to Examples a, b, and c described above (the benzylation degrees of the chips were 21%, 38%, and 51%, respectively) and the conventional molding material (particulate board) were used. , Etc.) was subjected to a decay test with Pleurotus cornucopiae, and the weight reduction rate of each subject was investigated. As is clear from Table 1, the weight loss rate after the decay test decreases as the benzylation degree increases, and the weight loss rate of the board having a benzylation degree of 51% is only 0.7%.
In other words, it shows a very excellent decay resistance of 1/25 or less of the board according to the prior art.

[0023]

[Table 1]

By the way, the benzyl etherification reaction is considered to be a topochemical reaction that gradually progresses from the chip surface to the inside. Therefore, when a chip with a large shape (especially a chip with a large thickness) is compared with a thin chip, the degree of benzylation on the chip surface is the same and the heat fusion property between the chips is the same, but the benzyl inside the chip is the same. The degree of conversion varies greatly.
In other words, thin chips are benzylated to the inside, and the chips themselves have high heat-melting property, decay resistance, and water resistance.
The board (molding material) prepared by this also exhibits high heat melting property, dimensional stability and decay resistance. On the other hand, in the case of a chip with a large shape, reaction conditions for benzyl etherification (temperature,
If the time and the concentration of sodium hydroxide for pretreatment are the same, the fiber form is retained in the tip and the strength of the tip itself is small compared to a thin tip, and the strength of the tip itself is small. The mechanical performance of the board (molded material) prepared by the chips of the above is high. And
Due to the residual fiber form, an air layer is maintained to maintain the void structure inside the chip, and a warm board (molding material) having a thermal conductivity close to that of the raw material, for example, wood, is obtained.

To summarize the above description, in the present invention, the size of the raw material chips, the reaction conditions for the benzyl etherification (by setting the reaction temperature high, or by increasing the reaction time, or Also, the benzylation degree itself or the depth of the benzyl etherification layer in the chip can be adjusted by selecting the pretreatment solution concentration to increase the benzylation degree). The properties of the mold material) can be easily set as necessary such as having many properties of a raw material, for example, wood, or having many properties of plastic.

Since the heat-fusion property of the benzyl etherified chip is proportional to the benzylation degree of the chip, the heat-fusion property may not occur depending on the benzylation degree. However, even in a chip with a low degree of benzylation, the hydroxyl groups in the chip have been substituted to some extent by benzyl groups, and a chip prepared by heat pressing by spraying an adhesive on the chip that has been mildly benzyl etherified The mold material) has improved dimensional stability, water resistance, and decay resistance of the board as compared with the conventional particle board using untreated chips. Of course, these performances are inferior to those of a board (molding material) prepared by heat-sealing with chips having a high degree of benzylation, but conversely, moisture absorption and desorption, thermal conductivity, etc. similar to wood can be obtained. .

[0027]

EFFECT OF THE INVENTION The present invention is a novel material which is excellent in moldability due to its heat-melting property and is also excellent in decay resistance, water resistance, dimensional stability, etc. by using lignocelluloses as a raw material due to the constitution and operation described above. It can realize various molding materials. Further, this molding material having both the performance as the raw material and the plastic can freely adjust the strength of expression of any performance by changing the setting of the benzylation condition. Conventionally, for example, even if one wants to use wood, it is often unavoidable to use a plastic material because of its drawbacks (variability of products, perishability, lack of dimensional stability, etc.).
There are high demands for feel, warmth, color tone, moisture absorption and desorption, etc., and materials having these properties and having high moldability and product reliability such as plastic materials have been demanded. The invention meets exactly this need.

[Brief description of drawings]

FIG. 1 is a diagram showing a swelling ratio in water of a molding material according to an embodiment of the present invention.

FIG. 2 is a diagram showing a result of a bending fracture test of a molding material according to an example of the present invention.

FIG. 3 is a diagram showing a relationship between specific gravity and internal bonding force in a molded material according to an embodiment of the present invention.

FIG. 4 is a diagram showing changes in the degree of thermal softening due to heating of benzyl etherified red pine wood flour.

FIG. 5 is a diagram showing a change in thermal softening degree with heating of powdered benzyl etherified chips.

Claims (11)

[Claims] 1. A plurality of chips formed by crushing raw materials such as wood, bamboo and other lignocelluloses are molded into a desired shape by hot pressing, and each chip is a benzyl etherified surface. A lignocellulosic benzyl etherified molding material characterized in that the two are strongly bonded to each other by heat fusion. 2. The lignocellulosic benzyl derivative according to claim 1, wherein each chip is benzyl etherified almost only in its surface layer and still retains the fibrous form of the lignocellulose as a raw material inside. Etherified molding material. 3. The lignocellulosic benzyl etherified molding material according to claim 2, wherein the bonding of the respective chips is performed by thermal fusion of the chips and an adhesive. 4. A wood comprising (a) lignocelluloses,
A step of crushing raw materials such as bamboo into chips, (b) a step of pretreating each of the chips with an aqueous sodium hydroxide solution, (c) a step of converting each of the pretreated chips into a benzyl ether, (d) At the end of the benzyl etherification reaction, a step of removing excess reaction liquid from each chip, washing with ether or alcohol, then washing with water and air-drying, (e) drying each of the chips to a desired size and specific gravity A step of forming a lignocellulosic molding material having a predetermined shape by heat-bonding the respective chip surfaces to each other by forming and heat-pressing as described above, and the method for producing a benzyl etherified molding material of lignocellulose comprising the above steps. 5. The method for producing a benzyl etherified molding material of lignocellulose according to claim 4, wherein benzyl etherification of each chip is performed by a liquid phase method using benzyl chloride. 6. The method for producing a benzyl etherified molding material of lignocellulose according to claim 4, wherein benzyl etherification of each chip is performed by a gas phase method using benzyl chloride. 7. The method for producing a benzyl etherified molding material of lignocellulose according to claim 4, wherein the benzyl etherification of each chip is performed by a liquid phase method using a mixed solution of benzyl chloride and xylene. 8. The method for producing a benzyl etherified molding material of lignocellulose according to claim 4, wherein the benzyl etherification of each chip is performed by a gas phase method using a mixed solution of benzyl chloride and xylene. 9. The method for producing a benzyl etherified molding material of lignocellulose according to claim 5, wherein the benzyl etherification of each chip is performed under heating and pressure. 10. The method for producing a benzyl etherified molding material of lignocellulose according to claim 5, wherein the benzyl etherification of each chip is performed by heating under normal pressure. 11. The chip according to claim 4, wherein substantially only the surface layer of each chip is benzyl etherified, the inside thereof retains the fiber form of the lignocellulosics as a raw material, and an adhesive is sprayed when the chip is formed. A method for producing a benzyl etherified molded material of lignocellulose, which is characterized in that it is heat pressed.