JPS61138722A - Production of wood-phenolic carbon fiber - Google Patents

Abstract

PURPOSE:To obtain the titled fiber having high tenacity, from wood waste, by introducing a substituent group to hydroxyl group of wood, dissolving the obtained plasticized wood in phenol together with a hardener, spinning the dope, heating and curing the fiber to obtain a wood phenol fiber, and carbonizing and baking the product. CONSTITUTION:Wood pulp is mixed and reacted with a mixture of trifluoroacetic anhydride and acetic acid in a reactor to substitute at least a part of the hydroxyl group of the wood pulp with at least one kind of substituent group. The resultant plasticized wood is dissolved in a phenol, and a hardener (e.g. hexamethylenetetramine) is dissolved in the solution. The obtained solution is used as a spinning dope, spun, and thermally cured to obtain a wood phenol fiber. The objective carbon fiber can be produced by carbonizing and baking the wood phenol fiber in an inert gas atmosphere.

Description

[Detailed Description of the Invention] (Field of Industrial Application) There is currently a strong desire to develop a more effective method of utilizing forest resources, which are renewable resources. In addition, in industries that use wood as raw materials, such as the Harp industry and the lumber industry, there is an urgent need to establish ways to effectively utilize wood waste.

Therefore, the present inventors discovered the fact that wood with plastic properties can be dissolved in 7 enols through a simple chemical reaction, and as a result of considering the advanced utilization of this dissolved material,
We have invented a technology to manufacture carbon fiber with sufficient strength.

(Prior art) In order to make more advanced use of wood, we aim to make more advanced use of wood-based raw materials, including wood, by imparting plastic properties to wood through simple chemical reactions such as esterification or etherification. Attempts to do so have been proposed.

For example, JP-A-57-103804 and JP-A-56-1
No. 35552 discloses a technique for esterifying or etherifying wood (powder) in which organic groups have been introduced into some of the hydroxyl groups, and the plasticized wood thus obtained can be used as it is or with various synthetic polymer substances. It is described that the mixture is used as a molding raw material. Furthermore, JP-A-57-2360 discloses a technique for preparing a solution by dissolving plasticized wood obtained by esterifying or etherifying wood (wood flour) by introducing hydroxyl groups into an organic solvent. It is also described that the prepared solution can be molded into a film either alone or in co-dissolution with various synthetic polymers.

However, the above method has the disadvantage that spinnability and moldability are insufficient.

As a result of various improvements, the present inventors discovered a method for obtaining carbon fiber from wood phenolic fiber.

(Problems to be Solved by the Invention) The present invention provides a novel method for obtaining carbon fiber from wood phenolic fiber.

(Means for Solving the Problems) In the present invention, wood that has been made into a plastic by introducing at least one substituent into some or all of the hydroxyl groups is dissolved in phenol under heating conditions, and the dissolved A curing agent is added to the solution to form a spinning solution. The spinning solution is discharged into the air from a spinneret, hardened under heating conditions,
Wood phenolic fibers are produced, and the fibers are carbonized and fired in an inert gas atmosphere to produce carbon fibers.

The raw materials for the production of plasticized wood are wood-pulverized pulp, mechanical pulp or partially or completely delignified pulp. Further, there is no restriction on the type of wood used as a raw material, and the method of the present invention can be applied to any type of wood. The plasticization modification reaction of the present invention, which introduces substituents into wood raw materials, is a reaction that introduces substituents that treat at least some of the hydroxyl groups of cellulose, hemicellulose, or lignin present in the wood raw materials, such as a reaction that introduces substituents that treat at least some of the hydroxyl groups of cellulose, hemicellulose, or lignin present in the wood raw materials. This reaction involves esterification or etherification. Esterification and etherification reactions are preferred as such plastic modification reactions.

Modifiers used for esterification and etherification include acids and derivatives thereof such as free a-acid halides and acid anhydrides, and halides such as alkyl halides and ethylene chlorohydrin. Suitable examples of substituents introduced by the plastic modification reaction include aliphatic acyl groups such as acetyl group, propionyl group, butyryl group, and valeroyl group, benzoyl group and other aromatic acyl groups, methyl group, ethyl A4, Examples include lower alkyl groups such as. Two of these substituents
It is also possible to introduce more than one species. 'The introduction ratio of substituents varies depending on the type of substituent, but in general, in order to obtain modified wood with good organic solvent solubility, the substitution ratio expressed as substituent morality is 7.5 or more. It is desirable that there be.

Here, "#substituent morality" refers to the number of moles of substituents introduced by substitution into wood tooy.

Plastic modification treatment can be carried out according to known techniques. Generally, powdered wood may be treated with a modifier in the presence of an organic solvent or a swelling agent at room temperature to elevated temperatures. Thoroughly wash the wood to be modified. For example, it is poured into methanol, filtered, and washed with water or methanol.

Then dry.

The dried glassy wood is then dissolved in phenolics.

A part of this technology for dissolving plasticized wood into phenols was reported at the 32nd Wood Science Society Meeting (1982). Phenols is a general term for compounds in which the hydrogen atom bonded to the benzene ring is replaced with a hydroxyl group.
Phenol, 0-cresol, m-cresol, p-cresol, 3.5-xylenol, 2,3-xylenol, 2.4-xylenol, 2,5-xylenol, 2
．． Examples include 6-xylenol and 3,4-xylenol. It may also be a mixture of the above phenols.

The melting device is a container with a cooler or a pressurized container. The melting temperature is 100-350℃, and the melting time is 15
The dissolution concentration of plasticized wood ranges from several centimeters to 80 centimeters on a weight basis, and for 25% or more, the plasticized wood and phenols are uniformly mixed using a kneader or other device before melting. Mix (necessary).

Furthermore, an organic solvent may be added during mixing to achieve more uniform mixing. They are alkaline with chloroform, acetone, methylene chloride, methanol, etc.

Examples of the curing agent include hexamethylenetetramine alone, or a combination of aldehydes such as formaldehyde, paraformaldehyde, and furfural with catalysts such as ammonia, amines such as trimethylamine and triethylamine, pyridine, or urea.

Next is the spinning process. If the curing agent is hexamethylenetetramine, add 3-3% of the above solution to 1 part (weight) of hexamethylenetetramine.
Mix on a moving table with 40 parts to completely dissolve and prepare a spinning solution. The mixing temperature is 70-90°C. Alternatively, aldehydes are added to the above solution and ammonia or the like is blown into the solution to obtain a spinning solution. The mixed spinning solution is introduced into an extruder equipped with a spinneret, heated to 100 to 150°C for 3 to 10 minutes, and then discharged from the spinneret into the air, and the discharged yarn is wound up by a winder.

The wound uncured discharge yarn is subsequently subjected to a curing treatment.

The curing method may be heating in air, and the curing temperature is 1.5
The temperature is 0 to 300°C, preferably 180 to 250°C.

The rate of temperature increase from room temperature is 10-b. Uncured fibers made of 100% phenol melt and lose their fiber shape before reaching the curing temperature.

On the other hand, in the case of wood phenol fibers, the fibers reach the curing temperature without melting and are cured while retaining their fiber form.
be able to.

When carbonizing and firing hardened wood phenolic fibers, there is no need for the conventional infusibility treatment process for rayo/, PAN, or pitch fibers, or for carbonizing and firing the fibers under tension. It is possible to perform carbonization firing in an atmosphere without tension or under tension.

Nitrogen, helium, etc. can be used as the inert gas, and the temperature increase rate may normally be 1°C/min to 50°C/min.

The carbonization firing temperature needs to be 800°C or higher.

Example 1 After drying, 3 g of Radiata pine refiner ground pulp (RGP) is weighed and placed in a reactor.

A mixture of 114 mmol of trifluoroacetic anhydride and 120 mmol of acetic acid, which had been aged in advance at 50°C for 30 minutes, was put into the reactor, the temperature was set at 50'C, and the mixture was allowed to react for 2 hours. After the reaction is completed, the reaction solution is dispersed in 151 methanol to decompose excess acylating reagent, and then dried. The substituent morality of the obtained modified wood was 12.6.

50 parts (by weight) of the modified wood thus obtained and 50 parts (by weight) of phenol are placed in a kneader and mixed at a temperature of 60°C for about 1 hour. After mixing, put the sample into a reactor equipped with a reflux device and reflux at 200-220°C for 6 hours to obtain a completely dissolved mixture. 1 part (by weight) of hexamethylenetetramine is added to 8 parts (by weight) of the solution and stirred at 90°C to dissolve hexamethylenetetramine.

The solution is used as a spinning solution. The spinning solution was put into a spinning machine heated to 150°C, and after being left for 5 minutes, a circular spinneret (hole size 0
．． 5m1n) into the air. The extruded filament was then stretched and wound up to a diameter of 40 μm.

The rolled uncured wood phenolic fibers were transferred to a furnace and heated from room temperature to 250'C at a rate of 20°C/min.
and hold for 30 minutes to complete curing.

Note that the atmosphere inside the furnace was air. The strength values of the obtained wood phenolic fibers are as follows. Tensile strength is 17k
y/ys” and elongation of 12%.

This wood phenolic fiber is heated with a nitrogen flow of 200 m1/min.
Placed in an atmospheric electric furnace and heated at a heating rate of 5.5° without tension.
Carbonization firing was performed by raising the temperature to 900° C. at a rate of C/min. The strength of this wood phenolic carbon fiber is 47.2
Yu/IIDI+2.

Example 2 After drying, 100 g of radiata pine thermomechanical pulp (TMP) was weighed and placed in a reactor. A mixture of 1.2 mol of acetic anhydride and 12.0 mol of acetic acid was put into the above reactor,
-Leave at room temperature day and night. Thereafter, further acetic anhydride5.
0 mol, acetic acid 1.2. Add a mixture of 0.2 mol of perchloric acid and 0.2 mol of perchloric acid as a catalyst, react at 45°C for 6 hours, and after the reaction is complete, neutralize with 0.015 mol of potassium carbonate and fill with deionized water for 5 hours. Afterwards, dry. The resulting modified wood had a morality of 12.1.

40 parts (by weight) of the modified wood thus obtained and 60 parts (by weight) of phenol were placed in a kneader and mixed at a temperature of 50°C for 1 hour. The mixed sample is placed in a pressurized container and heated at 250° C. for 3 hours to obtain a completely dissolved mixture. Add 1 part of hexamethylenetetramine (by weight) to 6 parts (by weight) of the mixed solution.
weight) and completely dissolved by stirring at 120°C to form a spinning solution.The spinning solution was placed in a spinning machine at 150°C and placed in a circular spinneret.

The filament was extruded into air through gold (pore diameter: 0.5 wm), then stretched and wound, and the diameter of the filament was 30 μm. The uncured wood phenolic fibers are introduced into a furnace in an air atmosphere and left at 250°C for 30 minutes to complete the curing process. This wood phenolic fiber has a tensile strength of 16.5
ky/rm" and elongation of 13 chi.

The wood phenolic fibers were introduced into an electric furnace with a nitrogen flow of 150 ml/min, and the temperature was raised at a rate of 5.5°C/min under no tension.
Carbonization firing was carried out by raising the temperature to 900° C. with mln. The strength of this carbon fiber is 52.4y7m2.

(1 other person)

Claims (1)

[Claims] By introducing at least one type of substituent to some or all of the hydroxyl groups, the wood that has been made into a plastic is dissolved in phenols, a curing agent is added and dissolved, and this solution is used as a spinning solution for spinning. A method for producing wood phenolic carbon fibers, which is characterized in that the wood phenolic fibers are then heated and cured to produce wood phenolic fibers, and the thus obtained wood phenolic fibers are carbonized and fired in an inert gas atmosphere.