DE1646769B2 - METHOD OF MANUFACTURING CARBON FIBERS OR FIBERS - Google Patents

Description

dende ^ SnxjspJpe ^ are arsenic treated.

even beijdea.-toeks VeiJiokten fibers fw ^ Jti ^ i the parallel 'EtoWfrfcnng of ψίπηε undi Zag? tension ak'zw'Scluäiäßig. υ-υ n ^

A i4er _ri , y $ A - patent specification

von PötyaJaylnitrilfasem 3ύίθίί heating hn-air on tea veH-15Q-bis-34Q ° C- 3 Su vi 1 t rck Se ^ lSi? * ^N 3 ^cn this Benandlun ^ 'BeF ^^' ^ in

in which the shrinkage of the kpntinu ^ ctieäi Eädsn odef; <2ewebe during jSir'Vl? treatment by ^j application of a train | Jinnungi preferably at least; 0 _? 5g / D. will not be delayed. As a result, blackened, non-baked polyacrylonitrile fibers are obtained. The · from this patent to. Tasks taken from the improvement 3 ^ jferruschen Eigenenschiifteii '' *? on 'Pbiyäcr ^ mffiJ fibers distinguishes ^! cti somft tfeuiffikh' from 8erjfieriigen the present invention, since in the said USA. patent is not mentioned at any point, the process for the The production of carbon fibers is important as long as it is intended. ^η

In view of the numerous efforts made to produce useful carbon fibers and the also numerous investigations for this with polyester fibers as a starting material there was no reason just the teaching of US Pat. No. 2,799,915 for the production of polyacrylonitrile fibers with improved thermal properties on the manufacture of carbon fibers according to the British Transfer patent 911 542. Apart from that, it could not be inferred that the application of Tensile stress during coking under non-oxidizing conditions. Fibers with improved mechanical properties Properties.

The following are examples to illustrate the invention, in which a multi-filament yarn is used as the starting material made of polyacrylonitrile with continuous single threads was used.

B ei s ρ i e 1 1

RUiirSwe ^ lSi? ^N 3 ^cn this
O (xSchtampfen dej Fgsffrj ^ ljycjbtung de
Overhead not shown in the fj ^ er -ierbungsebung
Change of J? IchtSTVÖ »4ifiauf 5,
j The FiäUBg-Mqdul which ^ aSän had
\ Benaüdiimg from 2.16 · 10 «kg / cmP to ^

e , -10 " kg / cm * changed, p ie ' mean

, g / g p

The tensile strength after this high temperature treatment was 14 ^ 1 · 10 -1 ^ cm ² . "

Example 2

Ot

Material and heat treatment were the same as in Example 1, except that the carbonization of the FädeE instead of the vacuum a hydrogen atmosphere of 50 mM Hg pressure in the furnace is maintained became. After the treatment, they would have charred föw. coked threads have the following properties:

■■ _{Density of the charred} threads .. .1.6 g / cm *
25th

Diameter of the final
; ^λ carbon threads 11 to 14 μ

Tensile strength ..., 9.5 ³ kg / cm *

Young's modulus 0.91 · 10 ^e kg / cm ²

Failure rate 1%

In the examples described above, shrinkage of the individual threads was observed, while the original circular shape of the cross-section was retained. The specified experimental data show that the diameter has decreased to about half.

A bundle of approximately 500 4 _^1/2 -Denier-Polyacrylnitrilfasem or threads, each about 27 μ in diameter and about 12.8 cm in length was hung as a starting material in a vertical tube furnace with attached weights of a total of 10 g, so that the Fibers were under tension. The furnace chamber was evacuated and the vacuum pumping process was then maintained throughout the heat treatment. The heat treatment consisted of increasing the furnace temperature to 100O ⁰ C at a rate of 15 ° C per hour. After this treatment, the charred or coked fibers had the following properties:

Density after coking 1.6 g / cm ³

Diameter of the obtained

Carbon threads _ .. 11 to 13 μ ί

^r

Tensile strength of each
Fibers;: i. ί 7.72 ··· 10 ^a kg / cm ²

Young module ^; 1.16 x iO * kg / cm ² ;

In [a further treatment stage. was.the Carbonase threads except for: one temperature

Example 3

2 _^1/2 -Denier-polyacrylonitrile were for 24 hours heated under tension to 22O ⁰ C in air to achieve complete permeation of oxygen throughout the fiber, and then carbonized in a non-oxidizing atmosphere up to 100O ⁰ C and up to 2500 ° C heat treated; Fibers were obtained having a tensile strength of 17.6 · IO ³ kg / cm *, while has been made in just a 2 hour long initial heating to 220 ° C fiber strengths of only 7.04 · IO ³ kg / cm ^2.

For the treatment in the above manner, but without the application of tension, the fibers shrank during the initial heat treatment at 220 ° C in air by up to 40% and the carbon fibers obtained by subsequent carbonization and heat treatment to 2500 ⁰ C weisettzwar a tensile strength under may be sufficient under certain circumstances, but the! Young's modulus is relatively low. If, however, the fibers nwill loaded during the heat treatment to anfängilichen _υ, 220 ⁰ C., dujch, train, ,,; _,, can both,, the ^ tensile strength Ί and; -des Ypung- ^ lpdul, increases _r weric! e
the following: table, shows :. \ ;, _{; y! r}

Uliij: iJ Tji *

■ Μ ".1; .V.

Burden one

Chamois from 100 threads of

2Vs denier

Polyaciylnitrfasem

at 220 ⁰ C above

24 hours

(G)

Change in length

during the

treatment

at 220 ^° C

properties of fibers

after coking treatment

up to 1000 ⁰ C generally inert

the atmosphere

Tensile strength (kg / cm ⁸ )

Young module

axial to the fiber

(kg / cm *)

Properties of the fibers

after heat treatment

up to 2500 ⁰ C in inert

the atmosphere

tensile strenght (kg / cm *)

Young module

axial to the fiber

(kg / cm *)

0 10 20th 30th 40

12%

15 7o

7.04 ■ 10 ³

7.04 · 10 ³

8.44-10 ^s

14.1 · 10 ³

14.1 -ΙΟ ³

Example 4

Polyacrylonitrile fibers or threads were wound onto a molded carbon body or spool with gentle tension and heated in air to 220 ° C. for 22 hours. The fibers were in the form of a yarn made of 100 threads of 2 ¹ / * denier polyacrylonitrile with 20 yarns per side of the former or spool, and these were fixed on the spool in such a way that by the inclination of the fixed fiber, with the application of heat to shrink, tension was maintained. After this initial heat treatment, the yarns were cut to 12.7 cm lengths and heated with 0.92 · 10 «1.13 · 10« 1.41 · 10 «1.48-10 « 1.48-10 »

5.62 7.04 8.44 14.1 14.1

10 ³ 10 ³ 10 ³ 10 ^s 10 ³

2.11 · 10 ⁶ 2.67 · 10 «3.3 · 10 ^β 3.73 · 10« 4.22 · 10 «

linear temperature increase from 200 to 1000 ° C in 24 hours in a hydrogen atmosphere of 150 mm Hg pressure. The properties of some fibers were afterwards

measured and the remaining heated in a coal tube furnace under argon from one atmosphere to 2500 ° C.

Another selection of the fibers obtained was tested and the remainder under the same conditions

heated ^{to 2900 0} C by one atmosphere of argon. The properties of the fibers obtained by this final treatment were determined. The results are summarized in the following table:

treatment

Properties of the resulting fibers

tensile strenght
(kg / cm ² )

Young modulus (kg / cm ² )

1. fibers heated 22 hours in air at 22O ⁰ C under train on the bobbin

2. Heating the fibers according to 1, from 200 ° C to 1000 ° C for 24 hours in a hydrogen atmosphere of 150 mm Hg

3. Heating of the fibers after 2. to 2500 "C for 2 hours in argon at 1 atm pressure

4. Heating of the fibers after 3. to 2900 ^c C under argon at 1 atm pressure for V ₄ hours

18.3 · 10 ³
18.3 · 10 ³
18.3 · 10 ³

1.41 · 10 ⁶ 3.52 · 10 "4.22 ■ 10 ⁶

Example 5

IVa denier polyacrylonitrile fibers were heated for 5 hours in an air-flow oven at 22O ⁰ C without application of tensile stress. The treated fibers were then carbonized in a vacuum oven under application of tensile stress different loads to 1000 ⁰ C. The resulting changes in length were measured. The fibers were then heat-treated up to 2500 ° C. without tensile stress. The mechanical properties of the carbon fibers thus obtained are summarized in the following table:

shrinkage

during the

oxidation

Tensile load: approx

during the

Coking

(kg / cm ² ; based

on the fiber cross-section)

Change in length

during the

Coking

^{(0 Zo):} asereigenschaften after heat treatment to 250o C ⁰

medium tensile strength
(kg / cm ² )

Young modulus (kg / cm ² )

-30 -30 -30

43
63

-9.0 -7.4 -2.0 6.9

9.3

10.1

10 ³
10 ³
10 ³

2.96 · 10 »3.45 · 10 ⁶ 3.38 · 10 ⁶

As can be seen from the table above, 65 becomes under the conditions analogous to this example

by applying tension as the example 3 increases, but without applying any

Load an improvement in the mechanical inherent stress (see first line of the table in example 3),

shafts of the final carbon fibers are achieved. becomes a tensile strength of 5.62 · 10 ³ kg / cm ² and a

7 8

Young's modulus of 2.11 · 10 * kg / cm ^{2 of} the final in the following proportions: 100 parts of resin on three Ge fibers reached up to 2500 ⁰ C after heat treatment. parts of each of the other two ingredients. These values are significantly worse than those of this. The fibers were uniformly with the resin mixture Example with tension during coking. soaked and formed a longitudinal reinforcement in the

From this it follows that especially favorable strength through hardening and solidification of the resin with roominess values can be achieved if the rigid composite material formed during the oxy temperature is resin / dative pretreatment a tensile stress imposed on fiber of high strength.

is that, however, also during the coking of the c) The procedure according to Example 6b was under

Polyacrylonitrile fibers applied tension an application of an epoxy resin mixture of 60 positives Effect on the strength properties of 40 parts by weight of epoxy resin and 40 parts by weight of polyester Has carbon fiber products. amid hardener repeatedly. The epoxy resin used was a

Resin based on bisphenol A with an epoxy

Example 6 equivalent from 180 to 200, an epoxy number of 0.5

to 0.55, a viscosity of 7 to 11 poise with butyl

In this example, the use of the glycidyl ether as a reactive diluent is used and the carbon fibers produced in Examples 1 and 2 are used as the hardener. A polyamidoamine of the formula is used
Reinforcement described in composite materials.

a) The following constituents were combined in a rubber _{- NH 2} (RNH) ₁ - [RNHOC-R '- CONH - (RNH) _x ] kneading or rolling mill (calender) _{- "RNH 2}

brought: ao

Fluoroelastomer copolymer made from Vinyliden- ™ ^ι an amine number from 210 to 230, an acid number

fluoride and hexafluoropropylene 100 g ^vo ° ? ^u " ^the viscosity from 400 to 1000 poise.

Magnesium oxide 15 g. _> «Hardening treatment at room temperature

Dicinnamic acid hexamethylenediamine ^led ™ ^the formation of a product with similar

(Hardener) 3 e * ⁵ properties as in example 6 b.

Carbon threads, 'manufactured according to the example Ϊ'. '.'. 20 g _v ^d > ^{A bundle νο} ° S ⁱⁿ . ^At _T ^s ? ^{iel l} manufactured

Carbon fiber was made with a solution of a resin

The fibers or threads were added to the Friedel-Craft type used, in particular a resin on material at the inlet gusset of the rollers, diphenyloxide-based, obtained by reacting the constituents where they were obtained in the following proportions over short lengths of about 3.2 mm had been:
broke and were then uniformly distributed over the material by mixing. The material 1 mole of dipheayloxide,
was then molded by a molding process and dissolved in 1.2 moles of p-xylylene chloride
the mold by heating it to 160 ^° C. for 1 hour

and further heat treatment at 25O ⁰ C for 35 in a dichloroethane solution with 40% solids 24 hours hardened The final product is more densely impregnated a. After evaporation of the dichloroethane composite rubber of great toughness, which at the impregnated fiber mass was shaped and at elevated temperatures maintains good strength properties 180 ⁰ C for 2 hours under a pressure of 35.2 kg / cm * thermoset to form a with

b) A bundle of unbroken, hard and stiff fibers reinforced according to Example 2 40 with high strength manufactured carbon fibers of about 10 cm long object.

was placed in a test tube with an inner diameter of 9.5 mm by the method according to the invention

knives tightly packed, and a given advantages catalytically cold-curing are the high strength and bePolyester resin was poured over the resin particularly smooth surface of the charred fibers and was made of a polyester resin mixed with methyl 45 threads, which they use as reinforcement in composite ethyl ketone peroxide and a 6% solution of materials makes it more suitable than C-fibers, which Cobalt naphthenate in turpentine oil substitute (white spirit) can be obtained from regenerated cellulose.

309517/45

Claims (6)

Γ - Strengthening for Verisil ^ jySaterialien, whose Matrixma patent claims - "* ifeM-atibn 6ä iHRpiCta ^ HHUiaArobci especially- '' special FädeiOpja the highest possible values for ri1 '' · · - ·; - · '■"' '- ■' " ■ ·· - strength and YÖtiii§ »module of interest si @. 1. Process for the production of carbon 5 The specific strength of such fibers or filaments fibers or filaments by coking of polyacrylic is usually higher, the smaller their nitrile fibers at about 1000 ⁰ C or more under not knife, however, the The production of such oxidizing conditions, if necessary with pre-fibers or threads of very small diameter, is a problematic oxidation treatment due to heat and very high strength,
Treatment of the polyacrylonitrile fibers in an oxy- ίο carbon fibers or threads were previously predating.AtBjdsphä ^ e bti. Lower temperature ^ considerably by v ^ coking of cellulose material doors, d ä du ^ rc hlg Idöehi ri.zeic hjräelt ^ l cEtßlj c ^ * ^ ¹ ® ^ igjdjrfierejiden conditions won. Other polymer treatment and / or at least one IeB of synthetic origin can also be used as the fibers or threads during the oxidation starting materials. A particularly suitable coking treatment for tensile stress is that of A. S h ϊ η d ο in J. Ceram ^ Assoc. sufficient to tme'-iätigsr Japan, 69 (1961) C 195, and Rep. Gov. Industr. Res. Shrinkage of the fiber at least partially to reduce Inst., Osaka, 1961, N. 317 (reported in reports of preventing or causing a stretching of the fiber. Deutsche Keramische Gesellschaft e.V., 43 [1966], 2. The method according to claim 1, characterized in p. 203), denotes polyacrylonitrile fibers, which are particularly characterized by the fact that the pre-oxidation by heat treatment should lead to excellent treatment in an oxygen-containing atmosphere in fiber products after pre-oxidation treatments. In the British patent temperatures from 200 to 250 ⁰ C is executed. 911 542, such a process for the 3. The method according to claim 1 or 2, characterized in the position of carbon fibers, wherein poly is characterized in that the duration of the heat treatment acrylonitrile fibers pretreated at 180 to 550 ⁰ C in oxygen-containing lung in an oxidizing or oxygen-containing atmosphere and then in the inert sphere for the complete permeation of the sour gas atmosphere at 700 to 3000 ° C are coked,
material through the individual fibers is sufficient. It has now been found that carbon fibers 4. The method according to any one of the preceding or threads with improved mechanical inherent claims, characterized in that the shafts can be obtained if at least fibers after coking, possibly below 30 during part of the manufacturing process pa-Zugspanmmg to a temperature up to above rallel to the effect of heat for one on the fibers 2000 ⁰ C are heated. or tension acting on threads is provided. 5. The method according to one of the preceding claims. characterized in that the named type is thus characterized in that the coking carried out in a hydrogen atmosphere or in a vacuum 35 fibers or threads during the oxidation treatment will. development and / or at least part of the coking 6. Use of the treatment according to one of claims 1 to be subjected to tensile stress, the to 5 obtained carbon fibers for production is sufficient to cause longitudinal shrinkage of the fiber fiber-reinforced composite materials, in particular at least partially to prevent or stretching special plastics such as synthetic hardened 40 to effect the fiber. Fluoroelastomers, polyester resin, epoxy resin or pre-oxidation by heat treatment in a Friedel-Crafts type resin. oxygen-containing or oxidizing atmosphere follows preferably at 200 to 25O ⁰ C (for example by heating in air), in particular for a duration of heat that is sufficient for complete permeation of oxygen through the individual fibers treatment is taken care of. If namely the preceding oxidation process, possibly one Part of the process is too short in duration, the fibers retain a soft core, and when the subsequent heat treatment at high temperature The invention relates to a method for making holes in the resulting fiber Manufacture of carbon fibers or filaments formed by or cavities. Coking of polyacrylonitrile fibers at about 1000 ⁰ C The required duration depends on it or more under non-oxidizing conditions 55 dimensions depend on the diameter of the respective fibers or, if necessary, with previous oxidation treatment threads; At a temperature of 220 ° C, however, heat treatment of the polyacrylonitrile results in a complete penetration of the fibers with acid fibers in an oxidizing atmosphere at low temperatures after about 24 hours of heating at low temperatures. 2V ₂ denier fibers and after about 50 hours The polyacrylonitrile fibers are supposed to achieve, according to a general length of heating with 4V ₂ denier fibers,
my parlance also copolymers or ter- The charring or coking of the fibers or polymers of acrylonitrile with other monomers, filaments are preferably made in hydrogen or im such as B. methyl methacrylate or vinyl acetate, vacuum. which are either used alone Further improvements in the properties of the or those compatible with these polymers, as examples 65 witnessed fibers are achieved when the fibers anspiel, phenolic resins or Friedel-Crafts condensation continues closing sate to the carbonization at about 1000 ⁰ C, are added. up to temperatures above 2000 ⁰ C, given- Carbon fibers or threads are z. B. as a failure also under tensile stress, in a non-oxy-