JPS60119214A - Production of bulky polyacrylonitrile fiber - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Acrylic fibers, ie fibers consisting of acrylonitrile homopolymers or acrylonitrile copolymers having at least 85 by weight acrylonitrile units, usually have a density of 1.17 to 1.19 t/ex''.

It is known to increase the density of acrylic fibers ("stabilization") to convert higher density acrylic fibers into carbon fibers. For example, polyacrylonitrile filaments are boiled in dilute KMnO4 solution for several minutes, then 150
Oxidation at ~220 °C for 2 to 8 hours has been proposed [1.
echnocogy', Vow, 13゜June issue (197
5), pp. 277-280].

U.S. Pat. No. 4,364,916 discloses polyacrylonitrile fibers by treating the fibers with hydroxylamine, washing and passing through a hot bath of ammonium, calcium or magnesium permanganate. Methods for stabilization are described. A further cleaning step follows, then approximately 240-310°C in an oxygen-containing atmosphere.
heat it to actually stabilize it. This stabilization takes about 35 minutes.

In addition to long stabilization times, this method has the disadvantage of multi-step processing. Furthermore, ammonium permanganate, calcium and magnesium solutions are difficult to obtain. With potassium permanganate, partial decomposition of the fibers is observed.

Therefore, the present invention has a density of 1.220 f/ty
The purpose of the present invention is to provide a simple method for producing polyacrylonitrile fibers of re' or higher.

This objective is achieved by adding hydroxylamine to the spinning solution, dry spinning the spinning solution, drawing the spun filaments, and heat treating.

Therefore, the present invention has been developed from a polymer having at least 85% by weight of acrylonitrile units by dry spinning a spinning solution, washing if necessary, drawing the spun filament and heating it to 1.220 f/c.
In a method for producing polyacrylonitrile filaments having a density greater than or equal to m'', a) hydroxylamine is added to the spinning solution, b) drawing is carried out to a ratio of 1:4 to 1:12, and C) drawn The substance is heated to 150-500℃, preferably 1
It is characterized by being exposed to contact heat of 60 to 220°C for at least 100 seconds.

Treatment with oxidizing agents such as permanganates is not required.

The addition of hydroxylamine to polyacrylonitrile spinning solutions is known from DE 27 24 952 A1. The filament obtained was not subjected to any heat treatment according to the invention and its density was 1.220 f/ag"
The required minimum value of hydroxylamine is not reached and hydroxylamine is added to reduce the flammability of the yarn rather than to increase density.

The amount of hydroxylamine to be added according to the invention is based on the content of nitrile groups.

Hydroxylamine is preferably added in an amount of 0.1 to 3 mole based on nitrile groups. Hydroxylamine can be added either directly or in the form of a hydroxylamine salt; in the second case, amines such as ethylenediamine, triethylamine, aniline A morpholine 1 pyridine, piperidine, dimethylpiperidine,
It is necessary to liberate hydroxylamine into the spinning solution by adding diethylenetriamine or triethylenetetramine.

After adding hydroxylamine, the spinning solution should be kept at a temperature of 50-150°C for at least 10 minutes before spinning. Hydroxylamine hydrochloride and hydroxylamine sulfate are diluted with a suitable hydroxylamine salt.

Acrylonitrile polymers containing at least 5s7Rffi% of acrylonitrile units forming the basis of acrylic fibers are well known to those skilled in the art. at least 9
Acrylonitrile polymers containing 8% by weight of acrylonitrile units, especially -values (Celulosechen+
ie 13 (1932) 58 ] to 60 - 120,
Preference is given to using acrylonitrile homopolymers, preferably 80 to 110. The polymer is spun by conventional means, e.g. from a 25-55% by weight spinning solution in dimethylformamide, dimethylacetamide or N-methylpyrrolidone, drawn, washed and preconditioned.
pare).

The strength of the filament thus obtained is 4-8 cN
/dtez, the fineness of individual filaments is 0.5-2
It is 0 dtex. The heat treatment of the filaments is carried out on a thermal contact surface, preferably on a slab, calender or heating rail, under a tension of 0.1 to 0.2 cN/dtec and ends after at least 20 minutes. Preferably, the contact heat treatment continues for 2 to 10 minutes.

The filament obtained by the method of the present invention is 1,5-
3. It has the strength of OCl/atex and is dark brown to black in color. The filaments can be processed into filter chlorides, filled and reinforced materials, or converted into carbon fibers by known methods.

The density is H, ae Vrie+q, H, G, Wel,
1land's 'Re5earchJourn,' 28
．． 8112 (1958) pp. 185-184.

Example 1 Acrylonitrile homopolymer 12 with a value of -90
．． 25kli', hydroxylamine hydrochloride 0,16
A mixture of 37.5 kQ of dimethylformamide and stirred at 80° C. for 1 hour was introduced into 37.5 kQ of dimethylformamide at room temperature. The obtained spinning solution was dry spun at a duct temperature of 160°C and an air temperature of 280°C. Take-off speed 2007
Individual filament fineness is 9.16tex at 11/min
It became. The spun filaments were drawn 7 times in water at 98°C, washed, conditioned, dried under tension at 180°C, and wound onto a bobbin.

Fiber data of the filament: Fineness: 1.4 dteχ Tensile strength: 4.8 N/dtex Elongation: 13 cm Shrinkage: 5 cm Density: 1.180 97 cm” Next, the filament was heated to an initial tension of 1 cN/dt.
, ex on 13 thermal slabs. The temperature is 180℃ on slabs 1 to 4, 200℃ on slabs 5 to 8,
It was 220°C on slabs 9-13. The results are shown in the table below ~240 Thin edge 1.184 4.6 9
00560 Darkening 11B8 4.3 8503 12
0 black/brown 1.220 2.8 7004240 black 1.250 1.9, 6505 560 black 1
．． ,! 120 1.7 600 A comparative test conducted under the same conditions as above but using a polyacrylonitrile homopolymer without hydroxylamine showed no increase in density during the test.

Example 2 A spinning solution was prepared, spun and processed as in Example 1. However, the amount of hydroxylamine hydrochloride and triethylamine added is 0.45 kg and o, sq.
kg corresponds to 3 molti based on nitrile groups.

Fiber data of filament: Fineness t 4 cltex Tensile strength 4.5 cN/atex Elongation 14% Shrinkage 2-inch density 1.180 f/an3 Filament initial tension 0.2 cN/dte+c
It was carried over 15 slabs as a Temperature value slab 1-4
170℃ on top, 190℃ on slabs 5 to 8, and 190℃ on slabs 9 to 8.
13 and 210°C. The results are not shown in the table below: 1 30 Light brown 1.1B3 4.4 85°2 40
Darkening 1.1864.2 13503 60 Darkening
1.192 5.7 7904 120 Black 1.28
0 2.5 7105 240 black 1.530 t5
Increasing the amount of hydroxylamine compared to 580 Example 1 further accelerates the increase in density.

Agent within [TI Akira

Claims (4)

[Claims] (1) Dry spinning a spinning solution from a polymer containing at least 85% by weight acrylonitrile units, washing if necessary, drawing and heating the spun filaments to a density of 1,220 P/as” or higher a) adding hydroxylamine to the spinning solution; b) drawing is carried out at a ratio of 1=4 to 1:12; and C) the drawn material is °C, preferably 1
A method as described above, characterized in that it is exposed to a contact heat of 60-220°C for at least 100 seconds. (2) A process according to claim 1, wherein the amount of hydroxylamine is from 0.1 to 3% by weight, based on nitrile groups. (3) Continue the contact heat treatment for 2 to 10 minutes, and remove the filament until the filament tension is 0.1 to 0.2 CN/dtl! I
A method according to claim 1 for maintaining X. (4) A method according to claim 1, wherein after adding the hydroxylamine, the spinning solution is maintained at a temperature of 50 to 150° C. for at least 10 minutes.