JPH026851B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) There is currently a great 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 pulp industry and the lumber industry, there is an urgent need to establish methods for effectively utilizing wood waste.

Therefore, the present inventors conducted a simple chemical reaction to
After discovering the fact that wood that has been given plasticity dissolves in phenols, and considering the advanced use of this dissolved material, he invented a technology to produce carbon fiber with sufficient strength.

(Prior art) For the purpose of making advanced use of wood, by imparting plasticity to wood through a simple chemical reaction such as esterification or etherification,
Attempts have been made to make more advanced use of wood-based raw materials including wood.

For example, JP-A-57-103804 and JP-A-56-
No. 135552 discloses a technology for esterifying or etherifying wood (powder) in which some of the hydroxyl groups have been introduced with organic groups, and the plasticized wood thus obtained can be used as 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 introducing hydroxyl groups and esterifying or etherifying wood (wood flour) in 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 fibers from wood phenol fibers.

(Problems to be Solved by the Invention) An object of the present invention is to provide 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 plastic by acetylating some or all of the hydroxyl groups is dissolved in phenols under heating conditions, and a curing agent is added to the solution. Add it to make a spinning solution. The spinning solution is discharged into the air from a spinneret and cured under heating conditions to produce wood phenol fibers, 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 in which acetyl groups are introduced into at least some of the hydroxyl groups of cellulose, hemicellulose, or lignin present in the wood raw materials. Esterification and etherification reactions are preferred as such plasticization modification reactions.

Modifiers used for esterification and etherification include free acids, acids and their derivatives such as acid halides and acid anhydrides, and halides such as alkyl halides and ethylene chlorohydrin.

The introduction ratio of substituents is the introduction ratio of acetyl groups.
Generally, in order to obtain modified wood having good organic solvent solubility, it is desirable that the substitution ratio expressed as substituent morality be 7.5 or more. Here, "substituent morality" refers to the number of moles of substituents introduced by substitution per 1000 g of wood.

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 plastic wood is then dissolved in phenols. A part of this technology for dissolving plasticized wood into phenols was reported at the 32nd Wood Science Society Meeting (1982). Phenols are
A general term for compounds in which the hydrogen atom bonded to the benzene ring is replaced with a hydroxyl group, including phenol, o-cresol, m-cresol, p-cresol,
3,5-xylenol, 2,3-xyresol,
2,4-xylenol, 2,5-xylenol,
Examples include 2,6-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 to 350°C, and the melting time is about 15 minutes to several hours. The dissolved concentration of plasticized wood ranges from a few percent to 80% on a weight basis, and for 25% or more, it is necessary to uniformly mix the plasticized wood and phenols using a device such as a kneader before melting. . Furthermore, an organic solvent may be added during mixing to achieve more uniform mixing.
They are chloroform, acetone, methylene chloride, methanol, ethanol, 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. When the curing agent is hexamethylenetetramine, 1 part (by weight) of hexamethylenetetramine is mixed with 3 to 40 parts of the above solution to completely dissolve it 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 was introduced into an extruder equipped with a spinneret and
After heating to ~150°C for 3 to 10 minutes, the yarn is discharged into the air from a spinneret, 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 150 to 300°C, preferably 180 to 250°C. The temperature increase rate from room temperature may be 10 to 60°C/min, or lower.

Uncured fibers made of 100% phenol melt and lose their shape before reaching the curing temperature. On the other hand, in the case of wood phenolic fiber,
It reaches the curing temperature with almost no melting, and can be cured while maintaining the fiber form.

When carbonizing and firing hardened wood phenol fibers, there is no need for the conventional infusibility treatment process for rayon-based, PAN-based, or pitch-based fibers, or for carbonizing and firing the fibers under tension. It is possible to carry out carbonization firing in an active gas atmosphere under no 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 refined ground pulp (RGP) was weighed and placed in a reactor.
A mixed solution of 114 mmol of trifluoroacetic anhydride and 120 mmol of acetic acid, which had been aged in advance at 50°C for 30 minutes, is placed in the above reactor, the temperature is set at 50°C, and the mixture is reacted for 2 hours. After the reaction is completed, the reaction solution is dispersed in 15 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 were placed in a kneader, and the temperature was 60
Mix at ℃ for about 1 hour. After mixing, the sample was placed in a reactor equipped with a reflux device and heated at 200-220℃ for 6 hours.
Reflux for an hour 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 placed in a spinning machine heated to 150°C, and after being left for 5 minutes, a circular spinneret (with a hole diameter of 0.
5min) into the air. The extruded filament was then stretched and wound to a diameter of 40 μm.

The wound uncured wood phenol fibers are transferred to a furnace where the temperature is raised from room temperature to 250°C at a rate of 20°C/min and held for 30 minutes to complete curing. Note that the atmosphere inside the furnace was air. The strength values of the obtained wood phenol fibers are as follows. Tensile strength is 17
Kg/mm ² and elongation 12%.

This wood phenol fiber was passed through a nitrogen flow of 200ml/
The material was placed in an electric furnace with an atmosphere of 100 min, and carbonized by raising the temperature to 900°C at a rate of 5.5°C/min in a stress-free state. The strength of this wood phenol charcoal fiber is 47.2Kg/ ^mm2 .

Example 2 Radiata pine thermomechanical pulp (TMP)
After drying, weigh 100g and put it into the reactor. A mixed solution of 1.2 moles of acetic anhydride and 12.0 moles of acetic acid was placed in the above reactor and allowed to stand overnight at room temperature. After that, a mixture of 5.0 mol of acetic anhydride, 12.5 mol of acetic acid, and 0.2 mol of perchloric acid as a catalyst was added and reacted at 45°C for 6 hours. After the reaction was completed, it was neutralized with 0.015 mol of potassium carbonate and deionized. After washing with water, dry. The resulting modified wood has 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 the temperature was 50%.
Mix for 1 hour at ℃. The mixed sample is placed in a pressurized container and heated at 250°C for 3 hours to obtain a completely dissolved mixture. 1 part (by weight) of hexamethylenetetramine was added to 6 parts (by weight) of the mixed solution, and the mixture was heated at 120°C.
The spinning solution is completely dissolved by stirring, and the spinning solution is placed in a spinning machine at 150°C, and a circular spinneret (with a hole diameter of
0.5 mm) into the air, then stretched and wound. The diameter of the wound filament was 30μ. The uncured wood phenol 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 tensile strength
The weight was 16.5Kg/mm ² and the elongation was 13%.

The wood phenol fibers were introduced into an electric furnace with a nitrogen flow of 150 ml/min, and the temperature was increased at a rate of
Carbonization firing was performed by raising the temperature to 900°C at a rate of 5.5°C/min. The strength of this carbon fiber is 52.4Kg/ ^mm2 .

Claims (1)

[Claims] 1. By introducing acetyl groups into some or all of the hydroxyl groups, the plasticized wood 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 comprises producing wood phenol fibers by heating and curing, and carbonizing and firing the wood phenol fibers in an inert gas atmosphere.