JPH06220213A - Lignocellulose molding and its preparation - Google Patents

Abstract

PURPOSE:To provide a new cellulosic molding not problematic from the viewpoints of environments and cost unlike the one produced by the conventional common pulp or viscose process and to provide the subject preparation process. CONSTITUTION:A lignocellulosic molding containing lignin and hemicellulose is prepared by extruding a composition prepared by dissolving acetic acid digestion process lignocellulose in a solvent mixture comprising a tr. amine N-oxide and a nonsolvent (e.g. water) for lignocellulose, stretching the molding, and removing the solvent from the stretched molding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lignocellulosic molded article containing lignin and hemicellulose and a method for producing the same, and more particularly to a technique for regenerating lignocellulose using an organic solvent that directly dissolves lignocellulose.

[0002]

2. Description of the Related Art Plants, which are present in large quantities in nature, are renewable resources and are inherently biodegradable. Therefore, from the perspective of environmental protection, its utilization is expected to become more important in the future.

Generally, plants have cellulose, lignin, and hemicellulose as main constituents, and cellulose is mainly used for the shaping process. This is because it is difficult to form a so-called lignocellulose containing lignin and hemicellulose. And, as a general manufacturing method of this cellulose-based molded article,
Lignin is removed by pulping wood (sulfite method, Kraft method, etc.), and a method of producing paper by taking out cellulose containing a part of hemicellulose as a main component, or taking out the taken out cellulose by film, fiber And a desired shape.

[0004]

However, in this pulping method, since chemicals such as sulfurous acid, caustic soda, and sodium sulfide are used, and chlorine-based chemicals are also used for bleaching,
It consumes a lot of energy during implementation, which is not desirable from an environmental perspective. Further, even in the viscose method, it is difficult to anticipate future development because it requires a great deal of cost for pollution control.

Under these circumstances, there is a demand for a novel cellulosic molded article which replaces the conventional technique, and in connection with this, a new solvent for cellulose (particularly an organic solvent which does not cause pollution) is required. Research is ongoing. For example,
It is well known that tertiary amine N-oxide dissolves cellulose in the presence of water (for example, JP-A-54-99148). Also, this tertiary amine N
-Oxides also dissolve explosive lignocelluloses in H. CHANZY et al. (See, for example, Journal of Applied Polymer Science Vol. 40).
Page 427 1990, Polymer Comunications 27th
Vol. 171 (1986). Furthermore, in the method for separating cellulose, hemicellulose, and lignin into constituent components, a technique of pulping by acetic acid digestion using acetic acid as a solvent has been reported by Nimz et al. (Eg, Holz als Roh-und Workstoff. , 44 volumes, 20
7 (1986)).

[0006]

The object of the present invention is to replace the conventional pulping method and viscose method, and to provide a novel method which does not cause the environmental and cost problems as in these conventional methods. It is intended to provide a cellulosic molded article and a method for producing the same.

[0007]

Means for Solving the Problems As a result of intensive studies aimed at achieving the above object, the present inventors have found that the solubility of acetic acid digested lignocellulose to tertiary amine N-oxide is different from that of other lignocellulose (explosion produced lignocellulose). It has been found that it is superior to cellulose and the like and the physical properties of molded products such as fibers and films obtained from this solution are also good, thus completing the present invention.

That is, the present invention prepares a composition in which acetic acid digested lignocellulose is dissolved in a mixed solvent of a tertiary amine N-oxide and a non-solvent for lignocellulose, and the composition is extruded and stretched. , A lignocellulose molded product containing lignin and hemicellulose obtained by removing a mixed solvent from the stretched molded product, and a method for producing a lignocellulose molded product having such a step.

[0009]

The acetic acid digestion method lignocellulose used in the present invention is obtained by steaming wood chips with an aqueous acetic acid solution.
The technology of imz et al. can be used. Conventionally, as a method for obtaining lignocellulose, in addition to the acetic acid digestion method, a fine pulverization method, a steam explosion method, etc. are also known, but the lignocellulose obtained by these other methods has a large damage, so the physical properties of the obtained molded product Will be inferior. Further, in the present invention, it is considered that the excellent solubility of the acetic acid digested lignocellulose with respect to the tertiary amine N-oxide particularly affects the physical properties of the molded article.

In the present invention, it is considered that the lignin contained in the lignocellulose acts as a so-called stabilizer, which suppresses unnecessary depolymerization of cellulose. Therefore, when a composition (dissolution) in which acetic acid digested lignocellulose is dissolved in a tertiary amine N-oxide is prepared, a high-concentration stable dissolution solution containing cellulose having a high degree of polymerization can be obtained, which is expensive. No extra stabilizers are needed.

The tertiary amine N-oxide used in the mixed solvent in the present invention is a cyclic mono- (N-methylamine N-oxide such as N-methylmorpholine N-oxide.
Oxide) compounds are desirable. In addition to this, Graenacher et al., US Pat. No. 2,179,181.
The triethylamine N-oxide disclosed in the above publication can also be used.

As the non-solvent for the lignocellulose used as the mixed solvent in the present invention, various known solvents that do not dissolve lignocellulose can be generally used. It is considered that this non-solvent exerts an action of swelling lignocellulose fibers and promoting dissolution when the lignocellulose is dissolved in the mixed solvent. Further, the use of this non-solvent has the advantage that the solution viscosity can be lowered and the melting point of the tertiary amine N-oxide at the time of dissolution can be lowered to prepare a solution at a moderate temperature (about 70 to 150 ° C.). Specifically, water, dimethyl sulfoxide, N, N-dimethylformamide,
N, N-dimethylacetamide, N-methylpyrrolidinone, hexamethylphosphoric triamide, acetonitrile, sulfolane and the like can be used. It is particularly preferable to use water because it is suitable for spinning in air and can easily remove the final solvent.

In the present invention, the method of dissolving the acetic acid cooking lignocellulose in the mixed solvent is not particularly limited,
For example, a mixed solvent of a tertiary amine N-oxide and a non-solvent of lignocellulose is prepared in advance, lignocellulose is immersed in this mixed solvent to sufficiently infiltrate the solvent, and then the temperature range of 80 to 150 ° C. There is a method to dissolve by heating. In addition, there is also a method in which a mixed solvent containing an excess of a non-solvent for lignocellulose is sufficiently permeated into lignocellulose, and then the nonsolvent for lignocellulose is reduced and dissolved by heating and reduced pressure. In these dissolution methods, devices such as a dissolver with a stirrer, a kneader, and an extruder can be used.

As described above, the composition obtained by dissolving the acetic acid digested lignocellulose in the mixed solvent is used as a raw material, and this is subjected to extrusion shaping (spinning, extrusion molding, etc.) to obtain the molded article of the present invention. The composition ratio of the composition at the time of extrusion shaping,
Desirably, the tertiary amine N-oxide is about 50 to 90% by weight, the non-solvent of lignocellulose is about 5 to 30% by weight, and the acetic acid digested lignocellulose is about 5 to 45% by weight. For example, if the concentration of the acetic acid digested lignocellulose is too low, the viscosity of the composition is low, so that shaping tends to be difficult. Further, if the concentration of the lignocellulose obtained by the acetic acid cooking method is too high, the composition tends to have a high viscosity, and the dissolution tends to be difficult. The concentration of the non-solvent of lignocellulose has a large effect on the dissolution of acetic acid digestion method lignocellulose, and when this concentration is too high, it tends to not dissolve, and when the concentration is too low, the dissolution temperature becomes high and the viscosity is high. Therefore, it tends to be difficult to dissolve.

It is not always necessary to add a stabilizer to the composition as described above, but it is possible to add it. Especially when the composition is stored at a high temperature for a long time, the addition of the stabilizer is effective. For example, radical scavengers and antioxidants can be effectively used. Specifically, bases such as n-propyl gallate, ellagic acid and sodium hydroxide, phosphate compounds such as sodium hexametaphosphate, magnesium sulfate and the like. And the like.

Further, since lignocellulose usually contains various components, there may be a component insoluble in the tertiary amine N-oxide, and in the case of extrusion shaping, the insoluble component is previously removed from the composition by filtration. It is desirable to exclude it.

The extrusion shaping in the present invention is carried out by extruding the composition prepared as described above into a desired shape such as a fibrous or film shape in a gas such as air or nitrogen. Good. The extrudate is also stretched to improve its physical properties. This stretching may be performed, for example, by winding the extrudate from the molding die at a speed higher than the discharge speed from the die mouth. This draw amount is determined as the draw ratio of the winding speed divided by the discharge speed of the extrudate from the die. The draw ratio is preferably 3 times or more, but it depends on the specifications of the die used, the solution viscosity, the type of cellulose, the concentration of cellulose, the degree of polymerization of cellulose, the temperature, the solvent composition, and the like. This stretching orients the dissolved cellulose molecules and improves the properties of the resulting cellulose before it is regenerated.

Subsequently, if a part or all of the mixed solvent is removed from the stretched molded product, the lignocellulose molded product containing the lignin and hemicellulose of the present invention can be obtained. This solvent removal step may be carried out, for example, by immersing the stretched molded product in water or the like and washing it. This desolvation also fixes the properties improved by stretching. According to this stretching and solvent removal step, there is no need for stretching in a subsequent step by a stretching machine as in the conventional method, which is economically advantageous.

The molded article of the present invention obtained by such a step has physical properties not inferior to or better than the commercially available cellulose-based molded article. For example, the standard and wet tenacity of the lignocellulosic fiber which is one aspect of the molded article of the present invention is 1.4 to 4.7 g / d, the standard and wet cutting elongation is 5 to 14%, and the standard time is It has a great feature that the values of strength and cutting elongation in wet are almost the same.

[0020]

EXAMPLES The present invention will be described in more detail with reference to examples. In the examples, “%” is% by weight unless otherwise specified.
Means

Example 1 First, a white birch wood chip (air-dried product) was prepared using a 93% acetic acid aqueous solution containing 0.1% hydrochloric acid.
Acetic acid digestion method lignocellulose (moisture 326%, solid content composition: cellulose 84 obtained by cooking at 10 ° C. for 4 hours
%, Lignin 4%, hemicellulose 12%). 100 g of this acetic acid cooking lignocellulose and N-
300 g of a 60% aqueous solution of methylmorpholine N-oxide
And were placed in a dissolver equipped with a stirrer of 1000 cc and stirred for 60 minutes, and then allowed to stand for a whole day and night, whereby an aqueous solution of N-methylmorpholine N-oxide was sufficiently permeated into the acetic acid digestion method lignocellulose. Then, this is 10mmHg
When the water was gradually removed by gradually raising the temperature from room temperature to 150 ° C. under reduced pressure, lignocellulose was dissolved in the solvent. Water content is 15% of the total solution
At the time point (converted from the amount of water removed), a part of this solution was taken out and observed with a microscope. As a result, it was confirmed that the lignocellulose was completely dissolved and no undissolved substance was present.

The solution became viscous when the heating at this elevated temperature was continued, and when cooled to room temperature thereafter, the solution solidified. The composition of this solid is 10.
5%, N-methylmorpholine N-oxide 79.7%,
The water content was 9.8%.

Next, the solid material is finely pulverized, and the pulverized material is melted by an extruder and extruded into air (spinning temperature 100 ° C.) and stretched (stretching ratio 25 times) according to the dry jet wet method. Then, this was immersed in water to obtain lignocellulosic fibers.

The lignocellulosic fibers thus obtained were light brown colored and glossy fibers (yarn fineness was 50 denier / 10 filaments). When the tenacity and breaking elongation of this fiber were measured, the following results, which were almost the same as or better than those of commercially available regenerated cellulose fibers, were obtained.

Standard strength = 3.5 (g / d), cutting elongation = 5.0% Wet strength = 3.5 (g / d), cutting elongation = 5.0
%.

Further, in order to compare the physical properties of this fiber with other cellulosic fibers and the like, Table 1 also shows the standard tenacity and breaking elongation of commercially available viscose rayon, copper ammonia rayon and cotton.

[0027]

[Table 1] <Comparative Example 1> Instead of using 100 g of acetic acid digested lignocellulose, white birch wood chips at 215 ° C and 20 kg /
100 g of lignocellulose (moisture 330%, solid content composition: cellulose 82%, lignin 5%, hemicellulose 13%) obtained by steaming at a saturated vapor pressure of cm ² for 6 minutes and then bursting to a low pressure at once. In the same manner as in Example 1 except for the above, solvent penetration and water removal were performed. When the water content reached 10%, a part of this solution was taken out and observed under a microscope. As a result, many insoluble substances were confirmed. Subsequently, an attempt was made to remove water to dissolve it, but the insoluble matter did not decrease. Further, spinning was impossible with such a solution containing a large amount of insoluble matter.

[0028]

As described above, the molded article of the present invention is a lignocellulosic molded article containing lignin and hemicellulose, and a composition obtained by dissolving acetic acid digested lignocellulose in a specific mixed solvent is used as a molding material. Since it is used for extrusion shaping, stretching, and solvent removal, it has physical properties not inferior to ordinary cellulosic molded products, and it has problems in terms of environment and cost as in the conventional pulping method and viscose method. It can be easily manufactured without causing

Claims (6)

[Claims] 1. A composition in which acetic acid digested lignocellulose is dissolved in a mixed solvent of a tertiary amine N-oxide and a non-solvent for lignocellulose, the composition is extruded, stretched, and stretched. A lignocellulose molded product containing lignin and hemicellulose, which is obtained by removing a mixed solvent from a molded product. 2. It has a fiber shape and has an elongation at standard time of 5%.
The lignocellulosic molded article according to claim 1, wherein the strength is 1.4 g / d or more. 3. A step of preparing a composition in which acetic acid cooking lignocellulose is dissolved in a mixed solvent of a tertiary amine N-oxide and a non-solvent of lignocellulose, and a step of extrusion shaping and stretching the composition. And a step of removing the mixed solvent from the stretched molded product, which is a method for producing a lignocellulose molded product containing lignin and hemicellulose. 4. The method for producing a lignocellulosic molded article according to claim 3, wherein the draw ratio is 3 times or more. 5. The method for producing a lignocellulosic molded article according to claim 3, wherein the tertiary amine N-oxide is N-methylmorpholine N-oxide, and the nonsolvent of the lignocellulose is water. 6. The composition comprises 50-90% by weight of a tertiary amine N-oxide, 5-30 of a non-solvent of lignocellulose.
The method for producing a lignocellulosic molded article according to any one of claims 3 to 5, which comprises 5% by weight and 5 to 45% by weight of acetic acid digested lignocellulose.