DE1066355B - Process for the production of directly spinnable solutions of polyacrylonitrile or copolymers of the same - Google Patents

Description

GERMAN

PATENT OFFICE

D26571IVb / 39c

REGISTRATION DATE: OCTOBER 4, 1957

NOTICE
THE REGISTRATION
AND ISSUE OF THE
DISPLAY: 1. O KTO BER 1959

It is known that the production of polyacrylonitrile fibers usually by polymerization in the aqueous phase and processing of the resulting solid polymer takes place. This process comprises several successive processes, such as polymerisation, Filtering, optionally washing, drying, grinding and dissolving. It is therefore of a technical nature Interest in finding a process in which the polymerization takes place directly in the solvent can be and a spinnable solution is immediately formed.

There has been no lack of attempts to carry out such polymerizations. Generally failed this type of polymerisation at too low a molecular weight. Another disadvantage was too little Yields and thus too high a proportion of monomeric acrylonitrile in the spinning solution. '

However, it is entirely possible to polymerize acrylonitrile in the commonly used solvent To undertake dimethylformamide, so that an immediately spinnable solution is formed.

The advantage of the procedure given below is the achievement of a sufficient molecular weight, after which fibers with good properties are obtained, and in high yields of about 90%. Dicyclohexyl peroxide-2 and cyclohexanone peroxide mixture, tert-butyl hydroperoxide, di-tert-butyl peroxide, 2,2-bis (tert-butyl peroxide) butane, tert-butyl perbenzoate, Tert.-butyl peracetate and mono-tert.-butylpermaleate are not very suitable. The yields are partly too low, sometimes the molecular weights are not high enough. These peroxides are derived from Alcohols and ketones. Mixed peroxides from alcohols and acids are also unsuitable.

It has now been found that directly spinnable solutions of polyacrylonitrile or copolymers thereof with at least 85% acrylonitrile content can be prepared by polymerization in dimethylformamide in the presence of organic peroxides by making one from 15 to 45 percent by weight of acrylonitrile and optionally other monomers and 85 to 55 percent by weight of dimethylformamide existing solution in the presence of up to 5 percent by weight, based on the total weight of the solution, diacyl peroxides, prepared from saturated C ₂ - to C ₁₈ -fatty acids, is polymerized at 30 to 80 ° C for 10 to 60 ¹ hours.

As diacylperoxides of saturated C 1 to C 1 _S fatty acids come into question z. B. acetyl peroxide, ButyryP "peroxide", capryl peroxide, lauroyl peroxide and stearyl peroxide. Benzoyl peroxide, polymerized by the same method, led to sufficient molecular weights and yields, but strongly discolored solutions were obtained, so that benzoyl peroxide was used in the process for the preparation of immediately spinnable solutions

of polyacrylonitrile or copolymers of the same

Applicant:

German Academy of Sciences

to Berlin,

Berlin-Adlershof,

Rudower Chaussee 116-125

Dr. Andreas Hunyar and Evelin Domanski,

Teltow-Seehof, have been named as the inventor

Production of spinning solutions does not appear suitable.

Additives such as triethylamine, hydroxylamine, diethylaniline, pyridine, furthermore cobalt acetate, strong acids, such as superchloric acid and sulfuric acid gave no improvement over the tests without them Additions. .

It has also been found that it is not absolutely necessary to use peroxides directly. In the case of the lower fatty acids, the polymerization is achieved by using the corresponding fatty acid anhydrides and hydrogen peroxide and urea perhydrate, respectively. The proportions of temperature and reaction time are of the same order of magnitude as when using the dioxyl peroxides itself. It is also possible to start from peroxides, which are not made up of simple fatty acids but were made from fatty acid mixtures.

It is not necessary to exclude oxygen when preparing the solutions. During the polymerization on the other hand, it is necessary to prevent large amounts of oxygen from entering. For example Fully filled vessels polymerize to high yields, while half-filled vessels do not polymerize in the same time or show little implementation. When using pure acrylonitrile, cloudy, viscous ones are created Masses that, after heating to about 90 to 100 ° C

909 630/350

result in a clear and directly spinnable solution. If you use a mixture of instead of pure acrylonitrile Acrylonitrile and one or more polymerizable compounds, the amount of acrylonitrile about 85% and the total amount of the other polymerizable components correspondingly about 15%, the result is clear solutions that can be spinned immediately without heating. Such polymerizable Connections were e.g. B. styrene, methyl methacrylate and vinyl acetate.

The inventive method differs significantly from the known polymerization of Acrylonitrile in dimethylformamide with the aid of azo catalysts through the technical progress achieved, that the resulting solutions are not vesicular or do not lead to bubbling during the spinning process lead, circumstances that led to significant disturbances in the spinning process. In the peroxide process according to the invention the solutions can be spun immediately, while those obtained by known methods Solution of the azoisobutyronitrile require venting.

In the case of the method according to the invention, it comes at all no use of peroxides derived from alkyl groups, aldehydes, ketones or the like, and also no photosensitization in question. The application of light is for technical implementation disadvantageous. This disadvantage can be avoided when using acrylic peroxides; it is in In this case, a thermal activation is sufficient to initiate the polymerization.

Examples 1 and 2 serve as comparative experiments.

example 1

.. In 75 g of dimethylformamide (Dmf) and 25 g of acrylonitrile (Acn) were 0.5 g of dicyclohexyl peroxide (60% paste in dimethyl phthalate) and placed in an Erlenmeyer flask closed with a ground-glass stopper Polymerized for 49 hours at 50 ° C. The yield was 15%; the relative viscosity 1.96. That Although the molecular weight was sufficient, the yield was too low. The solution was not spinnable.

Example 2

Acn in Dmf as in Example 1 and 0.5 g of tert-butyl peracetate (50% solution in dimethyl phthalate), polymerized at 50 ° C. for 18 hours, gave a yield of 12% with a relative viscosity of 1.7. Here, too, the molecular weight was sufficient that Sales too low and the solution therefore not to be spun.

■. . : Example 3

Acn and Dmf as in Example 1 and 0.5 g dilauroyl peroxide, 95% strength (remainder lauric acid), polymerized at 50 ° C. for 24 hours. Yield 78%, η _Γβί 1.60. In 48 hours the yield rose to 94% and a value for ή _Γβϊ of 1.53. The solutions could be spun after post-heat treatment.

Example 4

ίο Acn and Dmf as in Example 1 and 3 g of butyryl peroxide resulted in a conversion of 62% with a value for η _Γε1 of 1.6 at 24 hours and 50 ° C.

Example 5

Acn and Dmf as in Example 1 were added with 0.5 g of urea perhydrate and an increasing amount of acetic anhydride added and polymerized as in the above examples. With an increasing amount of acetic anhydride the yield increases somewhat, but there is a stronger discoloration of the solution, the one could affect technical usability. The acetic anhydride concentration was 1.5 to 1.8 g, an amount of 0.5 to 1 g appears appropriate. A conversion of 85 to 90% takes place here.

Example 6

412.5 g of dimethylformamide, 137.5 of acrylonitrile and 2.75 g of di-lauroyl peroxide, polymerized for 47 hours at 50 ° C., gave the yield 88% and a value for r \ _Te x of 1.53. The solution was heated to 100.degree. C. for 1 hour before spinning and then precipitated through a nozzle with 120 holes with a bore diameter of 0.09 mm into a precipitation bath made of hexanetriol at 62.degree. The threads formed were yeasted through a hexanetriol washing bath at 90 ° C. and then stretched eight times in a hexanetriol bath at 115 ° C. The result was fibers with a titer strength of 3.3 g / denier with an elongation of 23% and a relative wet tensile strength of 87%.

40

Example 7

412.5 g of dimethylformamide, 137.5 g of acrylonitrile, 2.75 g of di-lauroyl peroxide and 2.5 cm ^{3 of} methyl methacrylate were polymerized at 50 ° C. for 45 hours. It has achieved a yield of 89.5% and 1.5 r \ _Te i. The solution was spun in the same manner as in Example 6 without heating. The stretching was seven and ten times. The tenfold drawn fiber showed the following data: titer 6.2 denier, strength 2.7 g / denier, elongation 24%, relative wet tensile strength 74%, relative loop strength 74%.

Example 8 Polymerization in the presence of acetyl peroxide

' No.
the sample

lot
Dimethylformamide

Amount of acrylonitrile

Acetyl peroxide yield

»/ 0

Molecular weight

after ⁷ I rel Staudinger

II.
III

37.5
37.5
, 75

12.5

.12.5 25

0.05 0.1 .0.4 4.2
6.2
16

33.5
49.5
64

1.96 1.76 1.71

70,000 54,000 50,000

Claims (2)

Patent claims: 1. Process for the production of immediately spinnable. Solutions of polyacrylonitrile or Copolymers of the same with at least 85% acrylonitrile content by polymerization in Dimethylformamide in the presence of organic peroxides, characterized in that one of up to 45 percent by weight of acrylonitrile and optionally other monomers and 85 to 55 percent by weight Dimethylformamide existing solution in 5 6 Presence of up to 5 percent by weight, based on 3. The method according to claim 1, characterized in that on the total weight of the solution, Diacylper- records that a mixture of oxides, produced from saturated C ₂ - to C ₁₈ - fatty acid peroxides is used. Fatty acids, at 30 to 80 ° C for 10 to 60 hours is polymerized. 5 Considered publications: 2. The method according to claim 1, characterized in Journal of Polymer Science, 17, pp. 275 to 290 draws that for polymerization instead of diacyl (1955); peroxides the corresponding acid anhydrides and Transactions of the Faraday Society, 52, p. 80 bis Hydrogen peroxide can be used. 88 (1956). ι 909 · 63Ο / 350 9.59