JP2848925B2 - Method for preparing solution of lignocellulosic substance - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for preparing a lignocellulose solution used for a resin for impregnating a molding material, a curing agent for heat molding, an adhesive, and a paint. More specifically, the present invention relates to a method suitable for converting a lignocellulose substance containing a large amount of a hemicellulose component or a soluble low-molecular saccharide into a solution.

[Prior art] In order to protect the natural environment of the earth, protection of forests has been strongly called out, and wood resources cannot be used abundantly. In addition, the finite petroleum resources are recognized, and the price of synthetic resins depending on petroleum resources tends to increase in the long term. In order to cope with such a situation, lignocellulosic substances, such as wood, which are renewable resources, have been reviewed, and their effective use has been regarded as important. Therefore, new movements in which wood waste materials are chemically treated or dissolved and used as synthetic resin raw materials have been observed, and various methods for forming a solution of lignocellulosic substances such as wood have been devised.

For example, Japanese Patent Publication No. 61-2697 discloses a technique in which finely divided wood is reacted with phenol in the presence of a small amount of a mineral acid to form a solution, which is used as a binder. JP-A-57-2360 proposes dissolving a lignocellulose substance such as chemically modified wood in an organic solvent, and using the resulting solution as various resin raw materials.
Further, JP-A-61-261358 discloses that a solution of a lignocellulose substance can be obtained by adding a lignocellulose substance such as wood to phenols or bisphenols and heating to 200 to 300 ° C. I have.

The method for dissolving lignocellulosic substances is roughly classified into 2
One way. One is a method in which a lignocellulose substance is added to an organic solvent such as a phenol and heated to a temperature of 200 to 300 ° C. to form a solution. This method is called a high-pressure dissolution method because a pressure of about 50 atm is applied when the mixture is heated to a high temperature.

Another method is to add the lignocellulosic material to an organic solvent such as phenols and simultaneously add it to an acid catalyst to promote the decomposition of the lignocellulosic material. This method is
It is called the normal pressure dissolution method because it can be liquefied at a relatively low temperature of 100 to 200 ° C. and normal pressure.

The former method can dissolve a lignocellulosic substance in an organic solvent at a high ratio, thereby reducing the cost of raw materials, but requires a high equipment cost due to the need for an autoclave dissolution apparatus.

On the other hand, the latter method is capable of dissolving under normal pressure because the decomposition reaction is promoted by using a catalyst, but has the disadvantage that the ratio of addition of the lignocellulose substance to the organic solvent cannot be increased. Therefore, this method has the advantage that the equipment cost is low, but there is a limit in reducing the raw material cost.

A lignocellulosic substance such as wood is mainly composed of lignin, cellulose and hemicellulose, and also contains a small amount of low molecular soluble saccharides, polysaccharides, extraction components such as resins, and the like. These constituents vary greatly depending on the type of lignocellulosic substance, and some of them contain a large amount of low-molecular soluble saccharides and polysaccharides.

Although the details of the solubilization mechanism of the lignocellulose substance are not yet clear, it is considered that solvolysis is caused by acetic acid or formic acid generated by heating, or by an acid added as a catalyst. Lignin, which is one of the components of the lignocellulosic material, is cleaved to lower the molecular weight, and is converted into a solvophil molecule by the addition of a solvent molecule to be solubilized. Cellulose and hemicellulose are reduced in molecular weight by acid hydrolysis, and further, a pyranose ring is opened, dehydration reaction and the like occur, and a furfural compound, levulinic acid and the like are generated to be solubilized. At this time, dissolution of the crystalline region of cellulose is delayed as compared with the amorphous region. Therefore, long-time heating is required for complete dissolution.

[Problems to be Solved by the Invention] However, when the ratio of the hemicellulose component is high among the lignocellulosic substances or when a large amount of soluble low-molecular-weight saccharides is contained, the decomposition products are re-formed by performing the heat treatment for a long time. A reaction such as polymerization or esterification is caused to polymerize and an insoluble precipitate is generated.

For this reason, when solubilizing a lignocellulose substance containing a large amount of a hemicellulose component or a soluble low-molecular-weight saccharide, increasing the ratio of the lignocellulose substance to the organic solvent increases the dissolution time, resulting in an insoluble precipitate during the dissolution treatment. There was a problem that things were produced.

Also, in the case of the high-pressure dissolution method, if the lignocellulose substance can be dissolved under as mild a condition as possible, the equipment becomes cheaper in terms of equipment, which is economically advantageous. Thus, when dissolving a lignocellulose substance in an organic solvent, it has been a major problem to find a method for promoting the dissolution of the lignocellulose substance by a pretreatment or other methods.

Conventionally, a method of pretreating a lignocellulose substance with a halogen has been proposed as a method of accelerating solubilization (Japanese Patent Laid-Open No. 64-17961). However, this method deteriorates the working environment because halogen gas is generated during dissolution. And there is a problem that the melting apparatus is easily corroded, and the above problem has not been solved smoothly.

The object of the present invention is to produce without insoluble precipitates,
It is an object of the present invention to provide a method for preparing a solution of a lignocellulose substance, which can easily dissolve the lignocellulose substance without deteriorating the working environment.

[Means for Solving the Problems] In order to achieve the above object, the solution preparation method of the present invention comprises a step of adding a lignocellulose substance in advance when adding the lignocellulose substance to an organic solvent having a polymerizable active group. Immerse in lignocellulose material for 1 to 30 minutes by immersing in lignocellulose material for 0.5 to 24 hours, or immerse lignocellulose material in 0.1 to 5% dilute alkaline aqueous solution. It is characterized by soaking for 0.5 to 24 hours.

After this pretreatment, the above-mentioned conventional dissolution treatment of lignocellulosic material is performed.

The lignocellulosic material of the present invention includes wood flour, wood fiber, wood chips, veneer chips, wood chips such as crushed bark, stalks, leaves, and hakama of grasses such as high altitude, corn, and sugar cane. , Coconut palm, oil palm, crushed stem of palm plants such as sago palm, or waste paper, straw,
Vegetable fibers such as rice hulls; Among these, soluble saccharides, such as stalks of the above-mentioned grasses and crushed stems of the above-mentioned palmaceous plants, low molecular weight polysaccharides, lignocellulosic substances containing a large amount of starch, the effect of the present invention. Is remarkably shown.

Examples of the organic solvent having a polymerizable active group according to the present invention include phenols, alcohols, ethers, and ketones.

The pretreatment method of the present invention comprises first converting the lignocellulose substance to water at 10 to 100 ° C, preferably to 50 to 100 ° C for 0.5 to 2 hours.
It is a method of soaking for 4 hours. The higher the water temperature, the shorter the immersion time. If the temperature is less than 10 ° C. or less than 0.5 hour, the effect of the present invention cannot be obtained due to insufficient swelling of the lignocellulose material, and the effect remains unchanged even when immersed for 24 hours or more.
It is determined in the above range.

The second pretreatment method is to add 100 to 3 to the lignocellulosic material.
This is a method of steaming a lignocellulosic substance by passing steam at 00 ° C for 1 to 30 minutes. Preferably, it is superheated steam.
If the temperature is less than 100 ° C. or less than 1 minute, the effect of the present invention cannot be obtained due to insufficient swelling of the lignocellulosic substance.

The third pretreatment method is to reduce the lignocellulose material to 0.1 to
This is a method of immersing in a 5% dilute alkaline aqueous solution for 0.5 to 24 hours. Here, the diluted alkaline aqueous solution is caustic soda,
It is a dilute aqueous solution of alkali compounds such as caustic potash, sodium carbonate, ammonia, and organic amines. The effect of accelerating dissolution is exhibited even at a concentration of 5% or more, but is determined within the above range in consideration of safety during handling.

The pretreatment of the present invention is effective when dissolving the lignocellulosic substance under high pressure in the absence of a catalyst, but the same effect can be obtained when dissolving the lignocellulosic substance under normal pressure using an acid catalyst.

[Operation] By the pretreatment of the present invention, the lignocellulosic substance swells, an organic solvent or an acid easily permeates, and solubilization is promoted. In addition, pretreatment reduces hemicellulose, soluble saccharides and low molecular weight polysaccharides, and suppresses repolymerization of decomposed products during dissolution, so that lignocellulosic substances dissolve in a short processing time, and insoluble residues are significantly reduced. I do.

[Effects of the Invention] As described above, according to the present invention, dissolution of a lignocellulose substance is promoted, and a solution can be formed in a short time. Along with this, the dissolution conditions such as heating temperature and pressure are reduced, and the polymerization of the decomposed product of the lignocellulose material is prevented from polymerizing and the formation of precipitates. Can be enhanced.

Therefore, by dissolving the lignocellulosic substance by the method of the present invention, regardless of the high-pressure dissolution method or the normal-pressure dissolution method, it is possible to increase the turnover rate of the dissolving can and reduce the equipment depreciation cost per unit weight of the dissolving solution. can do. In addition, since the addition ratio of the inexpensive lignocellulose substance to the expensive organic solvent can be increased, the production cost of the prepared solution can be significantly reduced.

Further, the method of the present invention can dissolve a lignocellulosic substance without problems in safety and hygiene, without the risk of causing contamination of the working environment and corrosion of the dissolving device as in the prior art.

[Example] Next, an example of the present invention will be described in detail.

<Example 1> 350 g of crushed green stalks was immersed in hot water at 60 ° C for 2 hours, filled in a 1-volume autoclave, further sealed with 150 g of phenol. The temperature was raised to 250 ° C., the mixture was heated for 90 minutes with slow stirring, then cooled, and the liquefied product in the autoclave was diluted with dioxane. When the dilution was filtered through a glass filter having a pore size of 1 μm, 8.8 g of insoluble matter remained.

<Example 2> 350 g of the same pulverized high aleurone stalk as in Example 1 was immersed in a 1% aqueous solution of caustic soda for 1 hour, washed with water, packed in a 1-volume autoclave, and further sealed with 150 g of phenol. . Thereafter, the same treatment as in Example 1 was performed, and the diluent was filtered with a glass filter. As a result, 5.6 g of insoluble matter remained.

<Comparative Example 1> 350 g of the same pulverized high aleurone stalk as in Example 1 was liquefied in the same manner as in Example 1 without pretreatment, and filtered through a glass filter. As a result, 25.8 g of insoluble material remained. Was.

<Example 3> 20 g of birch sawdust was immersed in a 1% aqueous solution of caustic soda for 2 hours, washed with water, filled in a 100 ml stainless steel sealed tube, and further sealed with 30 g of phenol. 200-260
The mixture was heated to 2 ° C., heated for 2 hours while stirring slowly, and then cooled. Dioxane was added to the liquid inside the sealed tube to dilute the same, and the amount of insoluble matter was measured in the same manner as in Example 1. As a result, 0.63 g of insoluble matter remained.

<Comparative Example 2> Example 3 was performed without pre-treating 20 g of the birch sawdust of Example 3.
When liquefied in the same manner as above and the amount of insoluble matter was measured,
2.45 g of insoluble material remained.

<Example 4> Superheated steam at 110 ° C was passed through 20 g of bagasse powder as sugar cane pulp for 15 minutes, and then steamed into a 100 ml stainless steel reaction tube.
-600) 15 g, 4 g of maleic anhydride and 10 ml of acetone were added and sealed. Raise the temperature to 250 ° C and slowly stir 9
After heating for 0 minutes and cooling and opening the reaction tube, all the bagasse powder was in solution.

<Comparative Example 3> Example 4 was carried out without pretreating 20 g of the bagasse powder of Example 4.
When the reaction tube was opened in the same manner as described above, the bagasse powder was not completely dissolved, and a porridge liquid was prepared inside the reaction tube.

<Example 5> 250 g of the core pith of a high stalk was immersed in warm water at 80 ° C for 1 hour, and then packed in a 1-volume autoclave, and phenol 25 was added.
0 g and 20 g of a 53% aqueous solution of p-toluenesulfonic acid were added and sealed. Raise the temperature to 150 ° C and slowly stir for 60
After heating for a minute, a black-brown, homogeneous solution was obtained.

<Comparative Example 4> 250 g of the same core pulp of the high spikelet as in Example 5 was treated in the same manner as in Example 5 without pretreatment, and the autoclave was opened. Without this, a porridge liquid was prepared inside the autoclave.

The pretreated lignocellulosic materials of Examples 1 to 5,
It was found that the dissolution was remarkably accelerated as compared with those of Comparative Examples 1 to 4 without pretreatment.

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Claims (5)

(57) [Claims] 1. A method for preparing a solution of a lignocellulose material in which the lignocellulose material is dissolved in an organic solvent having an active group capable of polymerizing, wherein the lignocellulose material is dissolved in water at 10 to 100 ° C. prior to the dissolution. A method for preparing a solution of a lignocellulose substance, characterized by immersing for up to 24 hours. 2. A method for preparing a solution of a lignocellulosic material in which the lignocellulosic material is dissolved in an organic solvent having an active group capable of polymerizing, wherein prior to the dissolving, the lignocellulosic material is subjected to a steam at 100 to 300 ° C. for 1 to 1 hour. A method for preparing a solution of a lignocellulose substance, wherein the lignocellulose substance is steamed for 30 minutes. 3. A method for preparing a solution of a lignocellulose material in which the lignocellulose material is dissolved in an organic solvent having an active group capable of polymerizing, the lignocellulose material is dissolved in a 0.1 to 5% dilute alkaline aqueous solution prior to the dissolution. 0.5 ~
A method for preparing a solution of a lignocellulose substance, characterized by immersing for 24 hours. 4. The method for preparing a solution of a lignocellulosic material according to claim 1, wherein the lignocellulosic material is selected from the stems of plants of the Poaceae family including high altitude, corn, and sugar cane. 5. The method for preparing a solution of a lignocellulosic substance according to claim 1, wherein the lignocellulosic substance is selected from plant trunks of the palm family including coconut, oil palm, and sago palm.