DE1952388B2 - PROCESS FOR THE PRODUCTION OF CARBON OR. GRAPHITE FIBERS - Google Patents

Description

Numerous proposals for the manufacture of carbon fibers have been made in the literature. In general, the production takes place in such a way that an organic starting material present in fiber form is carbonized by heat treatment under inert gas. The carbon fibers obtained in this way are converted into graphite fibers by further heating to temperatures of up to about 3000 ^° C.

In addition to the output fibers for the production of strong and flexible carbon fibers easy accessibility, the following important requirements are made:

a) The material must not pass through a fluid state during carbonization, otherwise the fibers stick together, losing their flexibility.

b) The carbon residue should be as high as possible.

c) To achieve high space-time yields in the manufacturing process, the starting fiber must have a Rapid temperature increase without loss of strength and flexibility of the resulting Can withstand carbon fiber. The starting material must be readily available in fiber form be. The starting material should be characterized by a low price.

Numerous starting materials have been proposed, but none fully meet the requirements Conditions. Specifically, carbon and graphite fibers were made by carbonization and optionally Graphitization of natural or regenerated cellulose, polyacrylonitrile, polyvinyl alcohol, polyvinyl chloride and specially pretreated wool fibers (O. Vohler, E. Sperk: Ber. Dtsch. Keram. Ges. 43 [1966], pp. 199-208). According to British patent specification 1111 299, carbon fibers are through Carbonization of lignin fibers or mixed fibers from lignin derivatives with polyinyl alcohol, polyacrylonitrile or viscose. Attempts have also been made to use high-quality, highly polymeric materials by dispersing them to reduce carbon dust in the polymer fibers to be carbonized (Japanese patent 20 609/1963).

In French patent specification 14 65 030, bitumen or tar pitch melts ^{are spun into fibers at 240 °} C. and above, which then serve as starting fibers for the production of carbon and graphite fibers. With this method it should be achieved that, in addition to the above-mentioned expensive fiber materials, a very cheap product which is normally not available in fiber form can also be used as a starting material for carbon fibers. In addition to spinning at high temperature, the process has the main disadvantages that

juoächs the source material in its own Process step to a very specific C / H ratio must be brought and the tar fibers before carbonization with ozone or peroxides and then Air oxidation must first be made infusible.

From the large number of carbon compounds, only very few substances come into consideration as starting materials for carbon fibers. Overview Date failed so far to _{use) 0} promising substances to the fact that they are not accessible in fiber form. If a substance from a fluid phase is to be spun into threads according to the usual methods of the synthetic fiber industry, the spinnability of the fluid phase is the prerequisite for the spinning process. The spinnability is expressed by the fact that when a glass rod is immersed and withdrawn from such a solution, the liquid is drawn along as a more or less long thread and does not drip off, as is normally the case. The spinnability is a very special condition also the number of spinnable substances is limited and essentially comprises the known fiber materials of the synthetic fiber industry. _2S

The aim is here and hereinafter, the term carbonization, the thermal treatment of an organic substance to temperatures below 2000 ³ C, preferably at about 1000 ⁰ C, to be understood, wherein the heating at least above about 400 ⁰ C under an inert gas at normal pressure or reduced pressure is carried out. Graphitization should be understood to mean a temperature treatment between 2000 and about 3000 ° C. under protective gas.

The method according to the invention provides a remedy here, since it is easy to produce spinnable Solutions of a multitude of substances are made possible, which as such can be spinnable, but the others Conditions for the production of carbon fibers fulfill.

The proposed process for the production of carbon or graphite fibers by carbonization and optionally graphitization of starting fibers obtained by spinning solutions of organic substances is characterized in that the solutions to be spun contain one or more thread-forming linear polymeric substances which are soluble in the solvent and have a degree of polymerization of above 2000 in concentrations of 0.001 to 10 weight percent and containing at least one organic decomposable by carbonization into carbon substance with a lower degree of polymerization and having a melting or softening point above about 8O ⁰ C as a carbon source in a concentration of 5 to 60 weight percent.

To measure the spinnability, a method is used in the context of this patent that is described in the Literature is described and is based on the method customary in dry spinning. The to liquid to be examined is squeezed out of a nozzle under pressure and the length of the uninterrupted Liquid thread in cm, measured to the point where it breaks up into individual drops, as a measure of the Spinnability used (Kolloid-Zeitschrift, 61 [1932], p. 258). In the present measurements were the solutions at room temperature under 0.5 atmospheric pressure from a 400 micron nozzle and a nozzle channel length of 17 mm.

It was surprisingly found that solutions of organic substances used as starting materials for the production of carbon fibers can serve, d. H. by a carbonization treatment are decomposable to carbon, but as such do not show any sensibility, hereinafter referred to as carbon source referred to in a simple manner by iHe Presence of small amounts of high molecular weight substances composed of chain molecules (hereinafter referred to as thread former) can be made spinnable. The thread formers are in quantities from 0.001 to 10, preferably from 0.01 to 5 percent by weight added in all practically occurring In some cases, these concentrations are sufficient to achieve spinnability. In addition, it is one of the characteristics of the invention that the spinning of cheap organic by-products or waste products is made possible with only a small addition of a high polymer substance. The full one However, there is only an economic advantage if the spinnability is achieved through small additions.

The concentration of the carbon source in the solution can vary within wide limits. It is possible to use 5 to 60% solutions, but in general solutions are spun, whose concentration of the carbon source is between 10 and 40 percent by weight.

The process opens up the possibility of producing carbon and graphite fibers from a large number of organic fibers Obtaining starting materials, the use of which was previously not possible because they are not in fiber form could be won. So it is also possible to use natural or cheap by-products or waste products of synthetic origin to be processed into fibers, from which carbon and graphite fibers are then obtained can be. A sufficiently high carbon residue is a prerequisite for the suitability of an organic material in carbonization. Appropriately, it should be at least 10 percent by weight of the starting material be. In addition, the material must not pass through a fluid phase in the course of carbonization. This is always guaranteed when the melting point is significantly above the decomposition temperature lies.

From the large number of starting materials which are suitable for a person skilled in the art according to this information the following are mentioned as examples: starch, partially degraded or oxidized starch, dextrin, Hemicellulose, cellulose derivatives, such as. B. methyl cellulose, polymeric sugar derivatives such as pectin, pectic acid or alginic acid, protein substances such as casein, gelatin or isinglass, for internal salt binding Capable organic acid derivatives, such as glycocolla or betaine, sulfonic acids, their substitution products and their salts, especially ammonium salts, lignin, ligninsulphonic acid and their salts, especially ammonium ligninsulphonate.

According to the method according to the invention, however, it is also possible to use substances as Use carbon sources whose melting or softening point is below their decomposition temperature if the fibers spun from it are infusible before the actual carbonization power. In this case, the melting point or softening point should be that of that used as the carbon source Substances are expediently not below about 80 ° C. There are already numerous from the literature

Measures become known by which fiber materials, which soften before they decompose, can be remelted can be made.

In the German Auslegeschrift 12 55 629 a method is claimed, from a wool-containing starting material Manufacture carbon or graphite fiber material. Since the wool-containing raw material in a If the temperature treatment would lose its fiber structure, this must be avoided by taking special measures which consist in the fact that the starting material ι ο rial heated to about 200 ° C with a temperature increase of 5 to 50 ° / h with the admission of air, then with reduced air supply to about 300 ° C with a temperature increase of 1 to 10 ° / h and heated further then with the exclusion of air up to about 1000 ° C at one Temperature rise of 10 to 100 ° / h is heated, and that the heating is at least partially in one Containing formaldehyde, ammonia and / or carbon dioxide Atmosphere is running.

According to the French patent 14 65 030 already cited, tar fibers are treated with Ozone or peroxides and subsequent air oxidation made infusible In the Belgian patent specification 7 18 561 are fibers made of vinyl chloride copolymers, Polyvinyl alcohol derivatives and / or polyvinyl alcohol by treatment with acidic condensation agents below the softening temperature of the fibers made infusible. Concentrated condensation agents are preferred Sulfuric acid, difluoric and hexafluorophosphoric acid use polyvinyl alcohol, which is inert gas at approx. Melting at 230 ° C can be made infusible simply by pre-oxidation with air. A. S h i η d ο et al. (Polymer Preprints, 9, No. 2 [1968], p. 1327) also found that pre-oxidized polyvinyl alcohol A significantly higher carbon residue is obtained when the pyrolysis is carried out in the presence of HCl gas is carried out as if the pyrolysis is carried out under an inert gas.

From the large number of starting materials that soften or melt when heated and therefore must be made infusible before carbonization, the following are examples: polyvinyl alcohol, Polyvinyl acylates, polyvinyl chloride, polyolefins, polyesters, polyethers, polyanhydrides, polyures thane. Polyamides, polyureas, phenol-formaldehyde resins, both as pure polymers and in the form of their copolymers, graft polymers and their derivatives. These polymers which can be used as carbon sources, in contrast to the thread formers, do not need any to have linear polymer structure and differ from the thread formers further in that their Degree of polymerization below which the thread former is. By adding a thread former, here too Transferred spinnability to the solution of these polymers.

As Kohlenstoffqjelle the purposes of this patent application therefore all low or high molecular weight organic substances whose melting or softening points are above about 8O ⁰ C, which are soluble in a solvent and which are decomposable by a carbonization treatment to carbon apply. In particular, such substances are excluded, which have in addition to the mentioned features than 10 ⁰ / o solutions a spinnability of less than 10 cm. The carbon residue from carbonization should be at least about 10 percent by weight of the carbon source.

It must be particularly emphasized that the process according to the invention opens up the possibility for the first time molecularly disperse solutions and those of low polymer compounds, especially with Poiymerisa tion degrees below 50, through a dry spinning process (the designation of the spinning process success here and in the following from Ulimann's Er.cyklopädie de technical chemistry, 7 [1956J p. 263) to process fibers zi and thus füi as starting materials Carbon fibers can be used to make such compounds fertilize often before macromolecular substances zen have the advantage of better solubility and therefore allow higher solution concentrations to be used.

The thread formers that are used according to the invention are not only due to their linear polymeric structure Characterized by the level of their degree of polymerization or molecular weight only above a certain level The degree of polymerization shows solutions of high polymers at concentrations below 5% the property spinnability The choice of thread formers depends on the solvent used. For aqueous solutions, water-soluble high polymers are used, preferably polyethylene oxide, polyacrylamide or acrylic acid / acrylamide copolymers. In addition to the substances mentioned, other high polymers, such as. B. Polystyrene, polyisobutylene, polymethyl methacrylate or polyisoprene can be used.

Solutions of linear polymer substances have been used in spinning processes in the synthetic fiber industry since Used for a long time These solutions also show the property of being spinnable, but they are Molecular weights or degrees of polymerization of the substances used there are nowhere near as high as in the substances used according to the invention; Sufficient spinnability is only achieved in the concentration ranges achieved by 25 to 45%. So z. B. for the production of polyacrylonitrile fibers a 25% Solution of a polyacrylonitrile with a molecular weight of 35,000 to 50,000, which has a degree of polymerization of 660 to 950, spun in dimethylformamide (Ulimann's Encyklopadie der technischen Chemie, 7 [1956]). If 0.01 to 5% readings are made of such substances in a suitable solvent, however, these cannot be spun; when leaking from a nozzle there is only a sequence of Drops, but not a cohesive thread.

The spinnability of high polymer solutions as low in concentration as they are according to the Process of the present invention used depends critically on the degree of polymerization the substance used. To clarify this fact, the relationships in aqueous and organic media explained using a few examples.

2% aqueous solutions of polyethylene oxide can achieve different values of the spinnability depending on the level of the molecular weight or degree of polymerization. The solution of a polyethylene oxide A with a degree of polymerization .P of 5450 only reaches 30 cm, the solution of a polyethylene oxide B (P = 17,000) reaches 130 cm, polyethylene oxide C (P = 68,200) 225 cm and the spinnability of a polyethylene oxide D with P. = 136 400 is already well over 300 cm. For a more precise characterization of the substances, the limiting viscosity [η], measured in H2O at 35 ° C. with a shear stress of r = 12.5 dyn / cm ^{2, is} given (Tab. 1).

Table I.

/ 9 52 388

preparation

Limiting viscosity \ i) \ 35 ° C, degree of polymerisation H2O. r = 12.5dyn / cm2 P

Spinnable wedge of 2% Solutions cm

Polyethylene oxide A 2.0 Polyethylene oxide B 4.81 Polyethylene oxide C 7.1 Polyethylene oxide D 9.15

At a degree of polymerization of 136,400 ([ij] = 9.15) even a 1.5% aqueous polyethylene oxide solution shows a spinnability of 300 cm. Are 1.5% of this Polyäthylenoxtds in the solution of a carbon source, which as such no spinnability contains, this also has a spinnability of several meters. The spinnability of the High molecular weight polyethylene oxide has been transferred to the respective solution. If you want similarly high If the spinnability values with a polyethylene oxide reach a lower degree of polymerisation, its concentration must be correspondingly higher. So will z. B. a spinnability of 300 cm also from one Polyethylene oxide from Polymerisationsgred 6800 is achieved when the aqueous solution contains 23%

Polyacrylamides or acrylamide / acrylic acid copolymers and their salts are also suitable for aqueous systems suitable. B. an acrylamide / acrylic acid copolymer which consists of 85% polyacrylamide and has a degree of polymerization of 14 080, as a 1.7% aqueous solution a spinnability of 300 cm. A higher molecular weight product with a degree of polymerization of 70,400 already has a strength of 0.25% Solution in water has a spinnability of 300 cm. Of the

Table 2

5 450 30th 17000 130 68 200 225 136 400 more than 300

Viscosity ^{value In} '' ^r (determined in H ₂ O, 25 ° C, pH = 7;

0.05% solution with 0.1% NaCl at τ = 0.98 dyn / cm *.

where c is the concentration in grams / 100 ml of solvent) of this product is 35. Das The ratio of acrylamide to acrylic acid in the copolymers can be any value between Accept 0: 1 and 1: 0. Also a copolymer with

2.5% acrylamide (97.5% acrylic acid) is 0.8% Solution a spinnability of 210 cm. A similarly good spinnability is also achieved if the Acrylic acid of the copolymer is neutralized by salt formation. The salts are Li, Na, K and

in particular the NH ₄ - or substituted ammonium salts are suitable.

The following phenomena can be observed in 3% solutions of the polystyrene in CH ₂ Cl ₂ : The spinnability is at degrees of polymerization above about

10,000 significantly and increases with the degree of polymerization. In the case of particularly high molecular weight products, such as B. Polystyrene F, with a degree of polymerization of 125,000, a spinnability of at least 300 cm can be achieved with a 0.15% solution in CH ₂ Cl ₂

can be achieved (Tab. 2).

preparation

Degree of polymerization

concentration Weight percent in CHiCb

Spinnability

cm

Polystyrene A Polystyrene B Polystyrene C Polystyrene D Polystyrene E. Polystyrene F

1038
20 200
25,000
27 900
34 600
125,000

3
3

3
3
3
0.15

110

300

] Similar conditions exist with other high polymers, such as. B. Solutions of polyisobutylene in 1 trichlorethylene {Tab. 3).

t Table 3

preparation

Polymcrisatiomgrad

concentration Weight percent m Funnel-shaped ethylene

Sickness wedge

cm

Polyisobutylene A 6900 3 4th Polyisobutylene B 23 600 3 20th Polyisobutylene C 49,000 3 60 Polyisobutylene D 85 500 1.5 300

The 3% solution of a Porymethacrylsäuremethylesiers with a degree of polymerization of 3600 in CH ₂ Cl ₂ shows a spinnability of 10 cm, with a degree of polymerization of 15,000 ah 2% solution in CH ₂ Clj bcrem MO cm Fbcmo <md 3% solutions des Polyisoprene can be spun e.g. in toluene or trichlorethylene (degree of polymerization P = 25,000).

Polyethylene oxide, which can be spun in aqueous solution, also shows this property in organic solvents . B. CH ₂ Cl ₂ . Here, too, one observes

6ö9 585 378

\O

an increase in spinnability with the degree of polymerization. The effectiveness in CH2CI2 is even higher than in water. The polyethylene oxide with that Degree of polymerisation 6800 achieves a spinnability of 300 cm even as a 0.2% solution.

These phenomena can also be caused with other high polymers with a chain structure. This includes B. vinyl polymers and copolymers, diolefin polymers, polydienes, substituted polyethers and thioethers, polyesters, polyamides, polypeptides, polysaccharides, polysiloxanes, etc .. and mixtures of these substances. The limits for the occurrence of spinnability can be shifted somewhat depending on the nature of the high polymer and the solvent used. In any case, however, in the case of such substances in the range of high intrinsic viscosities [η] or high degrees of polymerization, a spinnability in solutions of very low concentration is observed, which can be transferred to solutions of carbon sources. On the other hand, by using polymeric substances with a low degree of polymerization, as found in most commercial products, no spinnability could be achieved in dilute solution, as was not possible with a polyethylene oxide below a degree of polymerization of 2000.

Thread formers within the meaning of the present patent application are therefore organic high-polymer, soluble compounds with a linear polymer structure. They preferably have degrees of polymerization above around 2000 on.

Commercially available solvents can be used as solvents. Your selection depends on the solubility of the carbon source. Solvents whose boiling points are below 200 ^° C. are expediently used. Water is preferably used as the solvent.

In the preparation of the spinning solutions, the procedure is that the solutions of the carbon source with a solution of the thread former is added until sufficient spinnability occurs, which is particularly important in the Range between 0.01 to 2 percent by weight of thread formation. based on the overall solution, the case isi. the The carbon source can also be dissolved directly in the solution of the thread former. Concentration can do this the carbon source can be varied within wide limits. At high concentration is generally a lower concentration of thread former is required, if the concentration of carbon-generating substance is low, larger amounts of thread-forming agent are required can be applied. The amount also depends on the nature of the solution; generally need more viscous solutions have fewer thread-forming agents than less fluid ones.

In some cases it has been found useful. the spinning solution to a certain pH cease, be it because of the solubility of the carbon source is thereby increased, be it. because the viscosity of the Spinning solution before pH aönangs. In some cases it can the solidification of the thread in the shaft can be accelerated by changing the pH. So is z. Legs ammoniacal solution of ammonium lignin sulfonate. which contains polyethylene oxide while flowing well the same solution in the neutral area is much more viscous when spinning the ammonia frills The solution decreases the pH value in the thread due to the evaporating NHj, whereby the viscosity increases; this leads to together with the competition for approval

evaporating solvents to solidify the thread. To achieve a pH value below 7 you can the known inorganic acids, in particular hydrofluoric acids, are added. Preferably however, organic mono- and polycarboxylic acids are used, such as. B. formic acid, acetic acid or oxalic acid, amounts of 1 to 60% being advantageous.

The spinning solutions obtained in this way have a number of desirable properties, In addition to the good spinnability, this is above all the relatively low viscosity and the associated one easy handling. The viscosity of these solutions can be between 0.1 and 100 poise, preferably but 1 to 10 poise; it is therefore below the values that are otherwise required for spinning processes. the Spinning solutions are therefore easy to filter, easy to degas and can easily be pumped through the supply line.

Wet and dry spinning processes come into question as the spinning process. However, a conventional one is preferred tional dry spinning process applied. The solutions are essentially at temperature Ren below the boiling point of the solvent used from one with a variety of nozzles provided spinning head. The threads run through a spinning shaft, depending on the one used Solvent, heated up to several hundred degrees and in the usual way by air or one Inert gas can be flowed through. In the shaft, the fibers up to a diameter of about 50 bi: warped about 1 micron. At the same time, most of the solvent is already removed. The first thin thread is concentrated and goes over a thick thread into the gel state. Ir At this stage the threads can still: contain solvents. After leaving the spinning The threads are wound up in the shaft. These faders now provide the actual starting point for you Manufacture of carbon and graphite threads.

The fibrous starting material is then, in a known manner, continuously or discontinuously, by increasing the temperature up to about 1000 ° C., into fibers consisting essentially of carbon, the heating having to take place at least above about 400 ° C. in an inert gas stream. If necessary, the starting fibers are subjected to a pretreatment prior to the actual carbonization, the z. B. in a special gas treatment, for example by HCL Cl ₂ . NO ₂ . SO3 or O ₃ . to improve the carbonization behavior or to prevent it from melting

The temperature behavior is determined in detail according to the used, carbon-generating output substance. As a guide to being successful! Carbonization can be the action of the well-known Process for the production of carbon fibers. wi (they are described in the patent literature, serve.

* Above 2000 ⁰ C to about 30 (XTC di <carbon fibers can be prepared by a temperature treatment under Schutzg optionally graphitized werdca

The carbon and graphite fibers produced according to the invention can be used for numerous uses. Yarns can be made from them using conventional working processes. Fabrics, felts, wadding and the like are produced, for example, as high temperature insulation, as filters for hot, aggressive gases and liquids. _{as a} reinforcement component "

¹ T

Composite materials, can be used as catalysts and catalyst carriers.

The following examples are intended to show the breadth of application of the process according to the invention:

example 1

300 g aqueous 40% ammonium lignosulfonate solution (SAP / N from Zellstoff Waldhof) were mixed with 100 g of a 2% aqueous polyethylene oxide solution (WSR 301 de- company UCC with [) j] = 9.15) and 45 g water. The solution was homogenized with the introduction of ammonia gas up to pH 10. The filtered spinning solution with 27% ammonium lignosulfonate and 0.4% polyethylene oxide was evaporated into a shaft which was heated to 80 ° C. and flushed with dry air the threads are wound on a rotating drum. The spinning cake removed from the drum was heated from 100 ° to 250 ° C. in air over the course of one hour. Thereafter, the filaments in a nitrogen stream initially up to 400 ° C with a growth rate of 40 ° / h and finally heated to 1000 ⁰ C with a growth rate of 150 ° / h were to result in flexible carbon fibers (carbon yield: 36%). A part of the carbon fibers was subjected to a graphitization treatment ^{by heating for two hours at 2600 ° C. under argon.}

Appropriately prepared 40 and 27% ammonium lignosulfonate solutions have no measurable spinnability without the addition of polyethylene oxide.

Example 2

300 g dextrin, 300 g glacial acetic acid and 300 g water were boiled until completely dissolved. 430 g of the filtered solution were concentrated to 320 g and iiiit 214 g of a 2% strength aqueous solution of an acrylic acid / acrylamide copolymer (Praestol 2935 from the company

S'.ockhausen with ⁿ '' ^r = 35.0) to a spinning solution

mixed, which contained 24% dextrin and 0.8% acrylic acid / acrylamide copolymer and was spun as described in Example 1. The Dextrinfäden were maintained for 5 hours at 220 "C under nitrogen. Then, the fibers were in nitrogen rom st to ^ 00 C with a growth rate of 10 ° / h and then heated to 1000 ⁰ C with a growth rate of 150 ° / h. flexible carbon fibers resulted (carbon yield · 18%) If a 24% strength dextrin solution is prepared in the same way without thread formation, its spinnability is only 3 cm.

Example 3

100 g isinglass solution with 56% dry matter (standard from O. Ring & Co.) were 190 g Glacial acetic acid and 122 g of a 2J% strength aqueous polyether oxide solution (WSR 301 from UCC with [17] = 9.15) added isnd homogenized by prolonged stirring The solution became threads of isinglass, as in Betspiel 1 spun and obtained therefrom by carbonization as described in example 2 carbon fibers (carbon yield: 15%).

Without the addition of polyethylene oxide, the isinglass solution kemertei spinnability.

Example 4

300 g (plate were dissolved in 300 g of hot water and, while stirring, with 300 g of glacial acetic acid and 100 g of a 2% aqueous solution of an acrylic acid / acrylamide oU, -ieris3t "{Praesto? W> from the company Stockhausen with ^ln " ^r = 35.0) mixed. The solution that is 20%

Gelatine containing 0.8% acrylic acid / acrylamide copolymer * was spun into gelatine threads as in Example I. (/ H up to 1000 ° C for 5 hours at 220 ⁰ C, with 30 ° increase in temperature per hour to 400 ° C and 150 °) (carbon yield: 21%) gelatin fibers were converted into carbon fibers by carbonization in a nitrogen stream. A 10% gelatin solution prepared analogously shows no spinnability without a thread former

Example 5

A spinning solution with 8.8% alginic acid and 03% acrylic acid / acrylamide copolymer was obtained by dissolving of 120 g of alginic acid in 560 g of formamide and, after thorough homogenization, with 680 g of a 1% solution of the acrylic acid / acrylamide copolymer used in Examples 2 and 4 obtained in formamide and ver as in the preceding examples to alginic acid threads have fun. From this it was possible to obtain carbon fibers analogously to Example 2 by carbonization. Without For the thread former, an 8.8% alginic acid solution in formamide cannot be spun

Example 6

33 g starch (amylium solubile from Merck), 33 g Water and 33 g of glacial acetic acid were concentrated to 62 g at the boiling point. After adding 153 g of water, 82.5 g 2% aqueous acrylic acid / acrylamide copolymer solution (Compare example 2 and 4) and 5 g of glacial acetic acid, the spinning solution contained 20% starch and 1% acrylic acid / acrylamide copolymer, from which, as in Example 1, starch threads could be spun. The carbonization analogous to example 2 yielded flexible carbon fibers (carbon yield: 21%). Will be a 20% Starch solution prepared in a corresponding manner without the addition of thread-forming agents, so it does not have any Spinability on.

Example 7

27 g casein were dissolved in dilute aqueous ammonia and reduced to a concentration of 20% brought. By adding 373 g of 2% aqueous polyethylene oxide solution of the same polyethylene oxide as in Example 1 and 3, a spinning solution with 123% casein and 0.75% polyethylene oxide was obtained, which was analogous Example 1 was spun into casein threads. From this, carbonization as in Example 2 described carbon fibers obtained (carbon yield: 22%). A solution made in the same way with 123% casein, but without the addition of potassium oxide has no spinnability whatsoever.

Example 8

A 30% solution in methylene chloride was prepared from polyvinyl acetate with a degree of polymerization of about 430. This solution had no thread tensile strength Spinning solution with 25% polyvinyl acetate and 05% polymethaicrylic acid methyl ester was obtained, which was spun as in Example 1 into vinyl acetate threads. Since polyvinyl acetate ^{melts above about 100 0} C, had to <fie

spun threads are first made infusible. For this purpose, some of the fibers were treated for 2 hours at room temperature with a nitrogen flow rate of 10 l / h which, before entering the reaction chamber, had been passed through 60% oleum and was charged with SO3. The fibers, which had been _{colored black by the SO 3} treatment, were heated ^{to 1000 °} C. within 3 hours in a stream of nitrogen. The carbon yield was 19%, in contrast to polyvinyl acetate, which had been heated to 1000 ^° _{C. under nitrogen without prior SO 3} treatment, the carbon yield being only 5.3%.

Example 9

35 g of "naphthol-1-disulfonic acid (3.8)" were dissolved in 65 g of 9% ammonia solution. The solution had no spinnability whatsoever. By adding 41 g of a 2% aqueous polyethylene oxide solution of the same polyethylene oxide as in Examples 1, 3 and 7, a spinning solution was 24.8% naphthol-1-disulfonic acid (3.8) and 0.57% polyethylene oxide obtained analogously to example 1 was spun into filaments the carbonization under nitrogen (heating rate to 400 ⁰ C. 57 ° / h and between 400 ° and 1000 ⁰ C, 170 ° / h) afforded flexible carbon (carbon yield: 40%).

Claims (10)

Patent claims: 1. Process for the production of carbon or Graphite fibers by carbonization or optionally graphitization of starting fibers obtained by spinning solutions of organic substances, characterized in that the solutions to be spun contain one or more thread-forming linear polymeric substances soluble in the solvent with a degree of polymerization of above 2000 in concentrations of 0.001 to 10 percent by weight and at least an organic substance which can be decomposed to carbon by carbonization and has a lower degree of polymerization and a melting or softening point above about 80 ^° C. as a carbon source in a concentration of 5-60% by weight. 2. The method according to claim I, characterized in that the carbon source is organic Substances are used whose spinnability as a 10% solution is at most about 10 cm amounts to. 3. The method according to claim 1 and 2, characterized in _{$ 2,} that are used as a carbon source water-soluble organic substances. 4. The method according to claim 1 to 3, characterized in that low polymers as the carbon source Organic compounds are used, the degree of polymerization between 1 and about 50 lies. 5. The method according to claim 1 to 4, characterized in that the concentration of the carbon source 10 to 40 percent by weight. 6. The method according to claim 1 to 5, characterized characterized in that the carbon source is organic Substances are used whose carbon residue during carbonization is at least is about 10 percent by weight of the starting material 7. The method according to claim 1 to 6, characterized in that the carbon source is organic Substances are used that do not pass through a fluid phase during carbonization or which are made infusible in a manner known per se prior to carbonization. 8. The method according to claim 1 to 7, characterized in that the Fadenbildnei in to spinning solution are present in a concentration of 0.01 to 5 percent by weight. 9. The method according to claim 1 to 8, characterized in that the thread former is a polyethylene oxide with a degree of polymerization above about 2000, which has an intrinsic viscosity [η] of 0.76 (measured at 35 "C, τ = \ 2.5 dynes / cm ² ) , or a polyacrylamide or acrylic acid / acrylamide copolymers or their salts (Li, Na, K, NH ₄ , substituted ammonium salts) with a viscosity value - "- above 4 (measured at the shear stress τ = 0.98 dynes / cm *, 25 ° C, pH 7.0.05% solution with 0.1% NaCl) or polystyrene with a degree of polymerization above about 10,000 or polyisobutylene with a degree of polymerization above 5000 or polymethacrylic acid methyl ester with a Degree of polymerization above 2000 or polyisoprene with a degree of polymerization above 10,000 is used. 10. The method according to claim 1 to 9, characterized in that a dry spinning process is used as the spinning process is applied.