DE1645276A1 - Process for the production of spinning solutions from acrylonitrile polymers or copolymers with a high acrylonitrile content, which are suitable for the formation of spinning threads with a high degree of whiteness - Google Patents

Description

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SNIA VI300SA SOOIETA'NAZIONALE INDU3TRIA

APPLIOAZIONI VISOOSA S.p.A. Via Cernaia, 8 - Milan, Italy

concerning

Process for the production of spinning solutions from aeryl nitrile

polymers or mixed polymers with a high acrylonitrile content, which are suitable for the formation of spider thread old high Yelsa grade,

The invention relates to a method for industrial production of spinning solutions made from acrylonitrile polymers or from Copolymers with a high acrylonitrile content, in particular is greater than $ 85. Ia particular relates to the invention Process for the direct preparation of aoryl nitride polymer solutions in dimethylformamide and aims to produce viscous solutions from which filament can be obtained have a considerably higher degree of whiteness than spun threads, which can be obtained from spinning solutions produced by known processes, so that ultimately more valuable ones Filaments can be obtained.

The inventive method is used in particular for the production of spinning solutions from ternary copolymers, which copolymers of acrylonitrile, which more than 85 ^ of the mixed polymer represents, from sodium allylsulfone, t and from Methyl methacrylate can be obtained.

In this case, the polymerization process, which is carried out in a mass that contains a high proportion of monomers, is closed interrupted at a point in time at which only a part, in principle not more than a third of the monomers, has been converted, as described in more detail in another application by the same applicant »

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Di · according to the general · in customary processes It is known that spinning solutions lead too considerably in alginic plants yellow thread and the solutions are seibat very dark. Even if the measures set out in the above parallel application are applied, this is not applicable to the The filaments obtained from the solution do not achieve a high degree of whiteness.

According to the invention it was surprisingly found that ■ on spun thread, which has the most desirable degree of whiteness » i.e. the most suitable optical characteristics for their commercial value and for their subsequent industrial exploitation own, can be obtained from solutions obtained from polymerization mixtures are prepared to which small amounts of thiourea dioxide have been added »

It has been shown that the addition of this substance not only results in the formation of spinnable, extremely bright and allows a weak yellow color, so that spun threads with result in a high degree of Veiss, but also has the further important advantage that the spinning solutions and the spun threads obtainable from them are prevented, later in the warmth the well-known sohädlichen phenomena of the To exhibit yellowing.

The use of thiourea dioxide is known in the polymerization of acrylonitrile in cases where as Catalysts azo compounds, such as azodiisobutyrnitrile, in amounts of 1-3 wt. 56 based on the weight of the monomers is added, be used «This use is both

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for example from German patent specification 1 089 172 known.

Also the possibility of preserving polymer solutions from later yellowing by using thiourine dioxide, but in association with boron trifluorides, for example from the German patent 95Ίk $ k , in which case the thiourethic dioxide in quantities of more than £ 1 based on polymer weight is used.

After the essential feature of the invention, the possibility became found that said beneficial effects using extremely low levels of Thioharnetbioxyd can be achieved in the special case of polymerizations of acrylonitrile in dimethylformamide, in which Lauryl peroxide or other organic peroxides can be used as a catalyst.

The invention has therefore a erhebliohen, unexpected technical progress, "it is, both in terms of knowledge of the beneficial properties, ¹ XLIE the spun yarn are awarded, which are obtained from spinning solutions duroh polymerization of acrylonitrile in .Dimethylformamid using organic peroxides as catalysts, and above all “with regard to the knowledge that very small amounts of thiourea dioxide, at least below 0.1C (based on the weight of the monomers introduced into the polymeric atlons), are capable of surprisingly an important improvement in the degree of brightness of the obtained spinning solutions and the degree of Veisse of the spinning threads obtainable from them.

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In particular, it was surprisingly found that the stated purposes rather than having the significant over $ 1 lying proportions of thiourea oxide, which so far provided and deemed necessary to achieve the listed effects, in the special case of manufacture of the spinning solutions under consideration by adding thiourea dioxide in extremely small amounts of $ 0.02-0.04, based on the weight of the material to be polymerized In addition, it has surprisingly been shown that an erosion of these proportions no improvement whatsoever on the achievable when using these surprisingly extremely low proportions Brings results.

The feasibility of the invention and the advantages that can be achieved by it are illustrated by the following examples of borrowed embodiments of the improved process.

EXAMPLE 1

In a reaction vessel made of glass with 2 liters of capacity, k jibe, a stirrer, thermometer, reflux condenser, and a StickstoffeinlassrOhrohen set at 60 * C thermostat 4p turn be introduced t

1) 605 grams of distilled dimethylformamide

2) 3 »25g sodium allyl sulfonate

3) 509 grams of distilled acrylonitrile

k) 15 g of distilled methyl methacrylate

5) 0.12g thiourea dioxide.

The thiourea dioxide is, as shown in the above quantities

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It can be seen that practically about 0.023 $ β · β weight of the monomers introduced into the mass to be polymerized. The introduced mass is slowly stirred and heated ^{to a temperature of about 58 ° C.} Then the catalyst is introduced, which consists of 2.8 g of lauryl peroxide dissolved in 50 g of dimethylformamide, which forms part of the 509 g listed at the beginning. The temperature rises nm some degree, which means that the polymerization has eingesetst · After 20 minutes, the mass appears trfibe and the polymerization is 0 continued with stirring at a temperature between 6Ό · and 65 * · After k constant polymerization when the composition has a has assumed a doughy, thick consistency, 55O # cold dimethylformamide is added to interrupt the conversion at the desired value.

The liquid, homogeneous mass is distilled in vacuo until 1250 g clear solution is obtained, which contains 16.5 % solid polymer. This solution is very slightly yellow in color and allows the production of fibers which have a degree of whiteness compared with that of filaments obtained from a solution which is produced in the same way, but without the addition of the very small amount of thiourea dioxide indicated has been improved a lot. These solutions are therefore nonsense only features favorable for the production of filaments with high quality, it was because the specified Weiseeeigensohaften, either (especially suitable for spinning), "it ei due to their molecular weight of 65" 000 because of the high Aorylnitrilgehaltes "EXAMPLE 2

In a reaction vessel with a capacity of 3 liters, k necks, a stirrer, thermometer, Rüekfluesk ^ äl «?, stiokstoff ~ ·.

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einlaserOhrohen and thermostats are gebraoht of lined · After a ·· t

1) 605 g of distilled di · · thyIfor »amide

2) 8.5 e sodium allylsulfonate

3) 590 grams of acrylonitrile

k) 15 S methyl methacrylate
5) 0.16g thiourea dioxide

The polymerization process is carried out as described in Example 1, ie a solution of 2.8 g of lauryl peroxide in 50 g of dimethylformamide, which forms part of the 605 g listed, is added to the mass heated to 58 ° C. The polymerization is thus brought rsm use and the temperature rises in a period of 20 minutes to a few degrees "Mach this period is continued, the polymerization about k hours at 60-65 ^e C., after which the mass is doughy and resisting the tubes · . A solution consisting of 550 g dimethylformamide, 5 g methyl metal aorylate and 1 g lauryl peroxide is then added and the mass, which has again become liquid, is further stirred. The temperature rises to about 70 ^° C and it is operated under such controlled conditions that the polymerization can proceed regularly until a total conversion of 7056 is reached · The liquid mass is now placed under vacuum and the unreacted monomers are immediately distilled off · The Distillation is continued until dimethylformamide alone distills. Such an amount of dimethylformamide is added to the viscous solution obtained that a viscous solution containing mixed polymer is obtained. The solution has a slight yellow color and it became spun threads with a high color

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Veissegrad produced «Dae obtained mixed polymer possessed • with a molecular weight of 50,000.

EXAMPLE 3

In a reaction vessel with a capacity of 2 liters, the is similar to those described in Examples 1 and 2 were, will

1) a mixture consisting of
426 grams of dimethylformamide
590 grams of acrylonitrile

32 g ethyl aorylate
0.17g thiourea dioxide, and

2) 138 g of a 6% sodium allylsulfonate solution in dimethylformamide, which was prepared warm and filtered, introduced.

The polymerization is carried out until the end of the first phase, that is to say until the end of the polymerization period of approximately k constant, at 60-65 ° C., as in Example 2. 550 g of dimethylformamide, in which 1 g of lauryl peroxide is dissolved, are then added and the mixture, which reaches a temperature of 70 ° C., is stirred further until a degree of conversion of about 7036 is obtained. The mass is then placed under vacuum and the unreacted monomers are distilled off. Man. receives a viscous solution containing about 20 pounds of misoh polymer which has a molecular weight of 52,000. The viscous solution has a good degree of brightness and provides filaments with a very good degree of whiteness.

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Claims (6)

PATENT CLAIMS 1) Process for the preparation of spinning solutions from polymers of acrylonitrile or a misoh polymer is high Acrylonitrile content, which are suitable in spun threads nit to be transformed to a high degree of ice, characterized in that a polymerizable mass of the monomer or « of the monomers in disethylforsasid a small one, under $ 0.1 lying amount of Thiohannetoffbioxyd is added. 2) Process according to claim 1, characterized in that 0.02-0.04 pounds of thiophosphorus dioxide, based on the weight of the monomer or monomers in the polymerizable material, are added to the polymerizable material. 3) Method according to claim 1 or 1 and 2, characterized in that the small amount. Thiourea dioxide, a mixture of three monomers, consisting of acrylonitrile and methyl setacrylate and sodium leulfonate, added in disethylforsaside will· k) Method according to one or more of the preceding claims, characterized in that the slightly yellow colored spinning solution is produced by partial polymerization of the monosers present in the mixture, which mixture also contains less than 0.13 thiourea dioxide. 5) Spinning solution that sowed according to the method or very one of the preceding claims was obtained by polymerization of a mass containing less than 0.1 and very much than 0.02 $ thiourea dioxide, and the one only very much has a weak yellow color. 009811/1615 -8- 6) Filaments that claim from a dope naoh 5 were obtained which were very much called $ 85 polyacrylonitrile Contains and duroh polymerization one, less than $ 0.1 and more than $ 0.02 thiourea dioxide, based on that Weight of the monomers containing mass was produced, and which have a high degree of Veisse. 009811/1615 -9-