DE1645276B2 - PROCESS FOR THE MANUFACTURING OF THERMALLY STABLE SPINNED ACRYLNITRILE HOMO OR MIXED POLYMERIZATES WITH HIGH ACRYLNITRILE CONTENT - Google Patents

Description

1 2

Made possible from the yellow coloration produced by the usual methods, but also the other

Spinning solutions of acrylonitrile homo- or mixed poly- has the important advantage that the spinning solution

merisates with a high acrylonitrile content in dimethylgen and the spun threads obtained from them later

As is well known, formamide is generally obtained when the heat does not produce the known harmful yellow

heavily yellow filaments, and the solutions themselves are colored.

are very dark. The inventive method is in particular

From the Belgian patent 572 665 the manufacture of ternary copolymers is from

position of spun acrylonitrile polymers more than 8 ° / ₀ acrylonitrile together with Natriumallyl-

or copolymers with sodium allylsulfonate sulfonate and methyl methacrylate are used,

and methyl acrylate in dimethylformamide with the help of io Here the polymerization process is preferred

known from catalysts. As catalysts can wise carried out in a mass that has a high

here either organic peroxides are used alone. Contains monomer content, and the polymerization

be, preferably, use is made is interrupted at a time in which only one

of a redox system that consists of an organic part, in principle not more than a third, of the

Peroxide (or an azo compound), SO ₂ and a 15 monomer is converted.

Ion of an oxidizable metal, such as Fe, or an The invention thus brings a substantial and aniline derivative consists. As can be seen, this known process has a double effect: on the one hand on the thermal, the presence of a reducible compound such as the stability of the filaments, which are _{necessary from spinning solutions, SO 2} , the SO ₂ obviously holding a 20 , which represents part of a redox catalyst by polymerizing, which always consists of acrylonitrile in dimethylformamide using a radical generator and a reducing compound of organic peroxides, for example lauryl pound. oxide, are generated as catalysts, and the main disadvantages of this known process, but above all with regard to the unavoidable corrosion effects, the surprising fact that even very little sulfur dioxide on the metal parts of the device is 0.1% (based on the weight of the monomers) exercises, as well as the dangers for the health of the lying thiourea dioxide quantities alone in the position operating personnel. are an important improvement in the degree of brightness

The use of reducing agents to bring about preferential of the spinning solutions obtained.

wise of thiourea dioxide in amounts of 1 to 30 In particular, it was surprisingly found

3 percent by weight, based on the weight of the represents that the stated purposes have already been achieved

Monomers, is to be used in the polymerization of acrylonitrile if one takes in place of the above 1%

in a concentrated solution of an inorganic thio content of thiourea dioxide, which was previously considered necessary

Cyanates were considered agile at pH values of 3.5 to 5.5 in cases that thiourea dioxide in

known, in which azo compounds are used as catalysts, amounts of only 0.02 to 0.04% (based on the

such as azodiisobutyronitrile are used. This adds weight to the monomers used. One

it is already possible to increase the amount of thiourea dioxide above 0.1% while maintaining the pH values

The color of the spinning solution during the polymerization does not improve the results in any way

to improve and to get threads from it, the one with it.

show less discoloration when heated (German 40 Ti ρ ϊ ς η i ρ 1 1

see exposition 1 089 172). ^p

There is also the possibility of thermo-preserving acrylonitrile polymer solution in a reaction vessel made of glass with a 2 liter capacity in dimethylformamide before it turns yellow, four necks, a stirrer, by adding thiourea dioxide, but a meter, reflux condenser, nitrogen inlet tube and along with boron trifluorides , with a thermostat set to 60 ° C, for example from the German patent specification 954 454, introduced in sequence:
known. The thiourea dioxide is dissolved in L ₆₀ Sg of distilled dimethylformamide,
Quantities of more than 1 _{%, based on the polymer 2} 3 _{25 sodium allylsulfonate}
sat weight uses _{3 5Q9 distilled} acrylonitrile,

It was now em a process for the production of 50 ₄ _ ₁₅ \ distilled methyl methacrylate,
thermally stable, spinnable acrylonitrile homo- ₅ _ ₀ , 12 g thiourea dioxide.
or copolymers with a high proportion of acrylonitrile by polymerizing acrylonitrile, if necessary. Weight of the introduced monomers. Thereafter, 2.8 g in 50 g Laurylperoxyd Dimethylformvon in the presence of thiourea dioxide in an amount less than 0.1 ° / _0> based on the total weight of dissolved amide, which listed a part of the beginning of the monomers, is polymerized. 60 605 g form, introduced. The temperature rises. It has surprisingly been found that a few degrees can be achieved, which means that the polymerization can be produced by means of polymers which, in turn, have set. After 20 minutes, the mass appears filaments revealed that the cloudy wünschenswertesten, and the polymerization is under stirring at degree of whiteness, the most suitable optical ISIN ie, a temperature between 60 and 65 ⁰ C continued sign own for industrial exploitation. 65 After 4 hours of polymerization, when the mass has reached a very thin, doughy, thick consistency, quantities of thiourea dioxide are added not only to the formation of 550 g of cold dimethylformamide, in order to make the very lighter spinnable solutions of extremely poor conversion interrupt at the desired value.

The liquid, homogeneous mass is distilled in vacuo until 1250 g of clear solution are obtained, which Contains 16.5% mixed polymer. This solution has a very faint yellow color and allowed the Production of fibers which have a degree of whiteness compared to that of spun threads which are made from a solution can be obtained which in the same way, but without the addition of the specified, very a small amount of thiourea dioxide produced is much improved.

These solutions are therefore extremely favorable for the production of high quality filaments Properties, either because of the specified whiteness or because of their molecular weight of 65,000 (particularly suitable for spinning), be it because of the high polyacrylonitrile content.

Example 2

In a reaction vessel with a capacity of 3 liters, four necks, a stirrer, thermometer, The reflux condenser, nitrogen inlet tube and thermostat are introduced in sequence:

1. 605 g of distilled dimethylformamide,

2. 8.5 g sodium allyl sulfonate,

3.590 g of acrylonitrile,

4. 15 g methyl methacrylate,

5. 0.16 g of thiourea dioxide.

The polymerization process is initially carried out as described in Example 1; H. the one to 58 ° C heated mass is a solution of 2.8 g of lauryl peroxide in 50 g of dimethylformamide, which is a part of the listed 605 g are added.

Polymerization then begins and the temperature rises by a few degrees over a period of 20 minutes. After this period of time, the polymerization is continued for about 4 hours at 60 to 65 ° C, after which the mass becomes doughy and resists stirring. A solution consisting of 550 g of dimethylformamide, 5 g of methyl methacrylate and 1 g of lauryl peroxide is then added, and the mass, which has again become liquid, is stirred further. The temperature rises to about 7O ⁰ C, and it is carried out under controlled conditions such that the polymerization may proceed regularly, until a total conversion of 70% was reached.

The unreacted monomers are immediately distilled off from the liquid mass under vacuum. The distillation is continued until pure dimethylformamide passes over. The viscous solution only so much dimethylformamide is added that a viscous solution with 20% copolymer is obtained, which is slightly yellow in color and from which spun threads with a high degree of whiteness are made. The copolymer obtained had a molecular weight of 50,000.

Example 3

In a 2-1 reaction vessel according to Example 1

1. a mix of

426 g dimethylformamide,
590 g acrylonitrile,
32 g ethyl acrylate,
0.17 g of thiourea dioxide and

2. 138 g of a filtered 6% strength sodium allyl sulfonate solution incorporated in dimethylformamide.

After heating to 58 ° C. with stirring, 2 g of lauryl peroxide, dissolved in 40 g of dimethylformamide, are added (part of the 426 g DMF under 1) added.

The polymerization will continue until the end of the approximately 4 hour first polymerization period at 60 to 65 ° C carried out analogously to Example 2, after which a further 550 g of dimethylformamide, in which 1 g of lauryl peroxide is dissolved, are added and the mass, which reaches a temperature of 70 ° C, is stirred further until a degree of conversion of about 70% is reached. The mass is then made under vacuum the unreacted monomers distilled off. A viscous solution is obtained which contains about 20% copolymer of molecular weight 52,000 contains. The viscous solution has a high degree of brightness and provides filaments with a very good degree of whiteness.

Claims (2)

Patent claims: 1. Process for the production of thermally stable, spinnable acrylonitrile homo- or -mischpolmerisaten with a high proportion of acrylonitrile by polymerizing acrylonitrile, if necessary together with sodium mallyl sulfonate and methyl methacrylate or with ethyl acrylate, in Dimethylformamide in the presence of an organic peroxide catalyst, characterized in that that in the presence of thiourea dioxide in an amount of less than 0.1%> based on the total weight of the monomers, is polymerized. 2. The method according to claim 1, characterized in that that 0.02 to 0.04%> based on the total weight of the monomers, thiourea dioxide are used and the polymerization is interrupted when the in the starting mixture contained monomers are polymerized to not more than a third, whereupon the rest Separating monomers from the solution.