EP0089593A2 - Process for the preparation of filaments or fibres from acrylonitrile polymers - Google Patents

Abstract

The invention relates to a process for preparing wet- or dry-spun filaments and fibers of polymers which consist to more than 50% by weight of acrylonitrile units and which are continually treated with an aqueous solution containing copper(I) ions during the fiber production process but before a first heat treatment above 100 DEG C. and the copper content in the fibrous material is fixed by heating to above 60 DEG C., preferably to above 100 DEG C. The filaments and fibers thus obtained can be dyed with acid dyestuffs, have bactericidal properties, and can be subjected to accelerated pre-oxidation.

Description

The invention relates to processes for the production of acrylonitrile-containing fibers and threads by a dry or wet spinning process, in which the fibers or threads which have not yet been healed by drying or a temperature treatment above 100 ° C. are continuously treated with an aqueous solution of copper (I) ions .

It is known to treat acrylic fibers with copper (II) salts to achieve a bactericidal action (cf. JP-OS 54 147 220).

The spinning of copper (II) salts with the same aim and as a catalyst for the oxidation of such threads in the production of carbon fibers is also known (JP-OS 49 035 629).

Treatment of acrylic fibers with copper (I) salts to achieve dyeability with acid dyes kan only in the beginnings of so-called _A crylfaserverarbeitung as cuprous ion-dyeing processes are used. A summary of this work is, for example, by Rath et al. in "Melliand textile reports" 38, (1957), pages 431 to 435 and 538 to 542. More recently, the aftertreatment of moldings with copper (I) salts has been described in JP-OS 51-90387 with the aim of catalyzing the preoxidation during the thermal stabilization of these products.

When copper (I) salts are reacted with polymers containing acrylonitrile building blocks, a cupro-ion complex is formed with the nitrile groups of the polyacrylonitrile. However, the subsequent implementation of copper (I) salts with shaped structures made of polyacrylonitrile is extraordinarily complex and, due to the instability of the copper (I) salts in aqueous solutions, especially at elevated temperatures, cannot be reproducibly controlled. The treatment of polyacrylonitrile powders with solutions of copper (I) salts leads to products which are insoluble in the known solvents for polyacrylonitrile or which form gel-like, non-spinnable masses. If, for example, copper (I) salts are added to a finished spinning solution, the spinning solution begins to gel and can no longer be spun without interference, while an extrusion of copper (I) salts containing spinning masses into injection molded articles may not yet be hindered.

So there was still the task of continuously producing copper (I) -containing acrylonitrile polymers in a simple and reliable manner within the manufacturing process in order to obtain copper (I) -containing threads and fibers which are suitable, for example, for dyeing with anionic dyes .

Surprisingly, it was found that spinning cables. or strands of individual threads, which contain acrylonitrile building blocks in their thread-forming substance, absorb large amounts of copper (I) ions from treatment baths even at room temperature, provided that these strands or cables have not yet been subjected to a temperature treatment above 100 ° C. or a drying process. The copper (I) ions are absorbed within seconds and can therefore be integrated into the production process of threads and fibers containing acrylonitrile without difficulty. It doesn't matter. whether the threads were produced by a dry or a wet spinning process. The copper (I) ions are particularly easily absorbed in wet-spun threads However, it is also possible to load dry-spun threads containing solvent within the washing process or aftertreatment process with copper (I) ions. Depending on the desired amount of copper (I) in the fiber, the treatment can take place before, during or after the washing of the strands or cables. The copper (I) content in the threads can of course also be influenced by the length of the exposure time and the concentration in the bath liquid.

The uptake of the copper (I) ions from a bath or from a spray zone at room temperature is largely reversible, i.e. the copper content can be removed by subsequent washing. For this reason, it is necessary to fix the copper content in the fiber. This fixation can be carried out by a temperature treatment above about 60 ° C, preferably above 85 ° C, or by a drying process in which correspondingly high temperatures are also exceeded.

Not only the temperature but also the dwell time is important for the fixing process. While the fixation in e.g. 65 ° C longer dwell times, at temperatures above 100 ° C only times of one minute or significantly less are required for the same effect. If the copper (I) ions are taken up from a bath at a temperature of more than about 60 ° C., the copper (I) ions are also fixed in the polymer molecule.

After such a temperature treatment, the copper (I) content can no longer be washed out, it is closed assume that under these conditions the copper (I) ions have been incorporated into the polyacrylonitrile in a complex manner.

A common procedure is to pull the cable or the strands through a copper (I) ion-containing bath and, after the excess bath liquid has been largely squeezed off, e.g. via hot godets from e.g. 100 ° C surface temperature. A further wash can then be provided in order to remove copper salts etc. adhering to the surface from the threads and to apply a customary preparation in a subsequent bath before the threads are finally dried.

However, it is also possible to treat the cables with a copper (I) ion solution immediately before the first drying and to fix them with drying. In this case, the threads have superficially non-complexly bonded copper compounds that can be detached on first contact with water. Instead of using heated godets or rollers, it is also possible to carry out the heat treatment to fix the copper content in a steam atmosphere, e.g. at temperatures above 95 ° C or using infrared radiators or by guiding them over a contact heat path.

• Eine entsprechende Lösung kann durch Lösung von Kupfer(I)-Salzen z.B. Cu Cl in Wasser erfolgen, wobei es wegen der schlechten Löslichkeit dieser Salze von Vorteil ist, die Lösungen in 20 bis 50 _%igen Natriumchloridlösungen herzustellen.

The treatment medium is in all cases an aqueous solution of copper (I) salts. There are various ways of producing such a solution. The following options are mentioned as examples:

• A corresponding solution can be obtained by dissolving copper (I) salts, for example Cu Cl, in water, it being advantageous because of the poor solubility of these salts to prepare the solutions in 20 to 50 _% sodium chloride solutions.

Furthermore, a copper (I) ion solution can be produced directly by electrolytic reduction of copper (II) solutions or by heating copper (II) salt solutions in the presence of metallic copper, the copper being added in the form of a powder or by electrolysis can be generated.

In addition, the solution can be prepared by mixing a copper (II) salt solution with a reducing agent. The copper salt CuS04 x 5 H ₂ 0 has proven to be particularly favorable as the usual copper (II) salt.

• Hierbei werden eine Kupfer(II)-Salzlösung in Wasser und eine wäßrige Lösung, die das Reduktionsmittel enthält, getrennt in das Bad in der Nähe der Einlaufstelle des Kabels zudosiert und im Bad vermischt. Es kann so sichergestellt werden, daß das Kabel jeweils mit frischer Kupfer(I)-Lösung beaufschlagt wird. Kabel und Badflüssigkeit fließen dabei im Gleichstrom, überschüssige Badflüssigkeit, die zweckmäßigerweise weitgehend verbraucht ist, wird in der Nähe des Kabelauslaufes aus der Wanne abgezogen und beispielsweise nach dem Auffrischen zurückgeführt.

Of the many possible reducing agents, aldehyde sulfoxylates, and in particular the sodium salt of hydroxymethanesulfinic acid, have proven to be particularly advantageous, since high copper (1) ion concentrations with good stability can be obtained with this system. The stability can additionally be increased by suitable complexing agents. The required low temperatures of the aqueous solutions make a significant contribution to the stability of the copper (I) solutions. In contrast to the old cupro-ion process, which was carried out at cooking temperature, a temperature close to room temperature is sufficient in almost all cases. If necessary, temperatures slightly above room temperature, ie from 25 - 30 ° C for example, can be used, since here the temporal constancy of the bath can be ensured by the simplest technical means. Since the stability of copper (I) solutions is only guaranteed for shorter times even at room temperature, the following procedure has proven to be particularly favorable:

• Here, a copper (II) salt solution in water and an aqueous solution containing the reducing agent are metered separately into the bath near the entry point of the cable and mixed in the bath. This ensures that fresh copper (I) solution is applied to the cable. Cable and bath liquid flow in direct current, excess bath liquid, which is expediently largely used up, is drawn out of the tub near the cable outlet and returned, for example, after refreshing.

The concentration of copper (I) ions can vary within wide limits depending on the desired fiber properties. If the copper (I) solution is reduced by reducing copper (II) - Connections produced, the reducing agent is to be used at least in the stoichiometric amount. A slight excess is preferably used in order to avoid the presence of copper (II) salts. In contrast to the copper (I) compounds, the copper (II) ions cannot be bound in a complex manner by the polymer molecules, so they are washed out during subsequent washing or dyeing processes and pollute the wastewater. A large excess of reducing agents generally has no further advantages. Rather, there is a risk that the copper (I) compound is further reduced to metallic copper, which can then no longer be embedded in the threads or fibers. An exception here seems to be the aldehyde sulfoxylates, in which even a larger excess at room temperature does not increase the copper deposition.

The processes customary in the art for the production of polyacrylonitrile fibers and filaments can be used for the process according to the invention. As already mentioned above, there are special advantages in the wet spinning process, since in general the diffusion of the copper (I) ions into the wet-spun threads is easier than with dry-spun threads.

The copper (I) ion solution can be applied by various known methods, for example by passing the cables or strands through a bath. However, it is also possible to apply the solution by spraying or the like. It is advantageous to squeeze the fiber cables or strands as far as possible before and after the treatment with the aqueous copper (I) ion solution. It can thus be ensured that the carry-over of the copper ions into other baths and an unnecessary dilution of the copper (I) ion treatment bath remains within tolerable limits. Of course it is from This is an advantage if measures are taken to ensure good and even penetration of a thread cable or strand in the treatment liquor. For example, cables should be routed so wide in the treatment bath that depletion of the copper ion concentrations or delayed penetration with the treatment bath inside the cable should be neglected as far as possible.

As already stated above, it is necessary to fix the copper (I) ions in the thread or fiber material by means of a thermal treatment. Only after heating to temperatures above 60 ° C., preferably above approximately 100 ° C., does the desired complex formation occur within a short time, and the copper compounds can then no longer be removed from the treated thread material by washing. In a subsequent wash after the heat treatment, the amount of copper compound that was on the surface of the thread material and could not be fixed is of course washed off.

Due to the treatment with copper (I) compounds, the treated acrylic fibers are more sensitive to heat than untreated threads. When heat treatment or drying, the temperatures must be selected so that a good degree of whiteness is maintained.

The acrylonitrile-containing polymers used are understood to mean those polymers which are composed of more than 50%, preferably more than 85%, of acrylonitrile units. Other possible components are, for example, acrylic acid, metacrylic acid and their esters and amides, vinyl acetate, vinyl chloride, vinylidene chloride, vinylidene cyanide or other unsaturated compounds copolymerizable with acrylonitrile. The threads and Fibers offer a wide range of applications.

For example, gently dried fibers that still have good whiteness can be dyed with acid dyes, they have bactericidal properties and can also be subjected to accelerated pre-oxidation for carbon fiber production.

The good dyeability with anionic dyes can be used to carry out the dyeing already during the manufacturing process. Today acrylic fibers are usually dyed with cationic dyes. This applies both to the discontinuous dyeing of the finished fiber and to the gel dyeing, in which the fiber is dyed in the gel state during the fiber production process before drying. Although cationic dyes already have high light fastness on acrylic fibers, the fastness of the dyeing with anionic dyes, such as e.g. can be achieved by the old cupro-ion process, can not be achieved. For this reason, when there are high demands on light fastness such as for fibers for the awning sector, expensive color pigments used in spin dyeing.

The process described above gives threads and fibers which can be dyed with anionic dyes without the difficulties of the old cupro-ion process, with usual dyeing times and conditions having to be observed.

It has now been found that it is possible; carry out the dyeing process at higher temperatures before the first drying or the first temperature treatment. In contrast to the normal dyeing processes deep staining is achieved here at low temperatures and residence times of just a few seconds. The dye liquor used can be used together with the copper (I) ion solution or in a separate bath after treatment with the copper (I) salt solution.

When using reducing agents to produce the copper (I) ion solution, care must of course be taken that the reducing agents used do not destroy the added dye. The separate treatment with a copper (I) salt solution and then a dye bath allows a faster change of the dye bath. On the other hand, it should be borne in mind that during the normal treatment of cables or strands with a copper (I) salt solution at room temperature, the copper is not immediately complex-bound and can therefore be triggered again in a subsequent dye bath. Appropriate temperature control, however, makes it possible in many cases to achieve a certain fixation of the copper in the fiber without irreversibly damaging the gel structure still present in the thread. If necessary, an intermediate temperature treatment at temperatures below 100 ° C leads to sufficient binding of the copper in the complex state, while the gel structure is still sufficiently preserved to ensure staining with anionic dyes within such a short time that continuous production of the dyed threads or fibers is possible.

The invention is illustrated by the following examples. Unless otherwise stated, parts and percentages relate to weight units.

example 1

• 50 % Dimethylformamid
• 50 % Wasser
• Temperatur 50°C. ,

A 17% solution of an acrylonitrile polymer in dimethylformamide was spun in a known manner by the wet spinning process. The polymer used consisted of 99.5% acrylonitrile and 0.5% methyl acrylate and had a relative viscosity η rel. from 2.9 to. The viscosity measurement was carried out on 0.5 percent by weight solutions in dimethylformamide at 25 ° C. The temperature of the spinning solution was 90 ° C., a 300-hole nozzle with a bore diameter of 80 μm was used. The spinning bath had the following properties:

• 50% dimethylformamide
• 50% water
• Temperature 50 ° C. ,

The freshly spun threads were withdrawn from the precipitation bath at a speed of 4 m / min, subjected to wet drawing at 85 ° C. of 1: 4.05 in a bath which consisted of 60% dimethylformamide and 40% water, and then with Wash water free of solvents at 30 ° C. After the washing process, the sliver was squeezed to remove most of the water and passed through a trough containing an aqueous solution of 100 g / l CuSO ₄ x 5 H ₂ 0 and 20 g / l of the sodium salt of hydroxymethanesulfinic acid (trade name: ^{(R )} Rongalit C) contained (residence time 1.5 sec.). The solution also contained the required fiber preparation. The solution was supplemented by continuous metering of an aqueous solution of 200 g / 1 CuS0 ₄ x 5 H ₂ 0 and an aqueous solution of 40 g / l of the reducing agent. The two solutions were mixed shortly before entering the treatment tub. The treatment bath had a temperature of 20 ° C. The copper sulfate solution ^* Formula: CH ₂ SO ₂ Na x 2 H ₂ O

which was needed for the strengthening contained at the same time the required fiber preparation.

After passing through the tub, the sliver was squeezed again and then dried on two heating godets at 140 ° C and then subjected to a stretching of 1: 1.12 to two heating godets at 160 ° C and then a further stretching of 1: 1.54 to two subjected to further heating godets with a surface temperature of 160 ° C and then brought to the reel by means of a cold take-off device. The filaments obtained had good whiteness and good drawability for acid dyes. The copper content of the fibers was 4.5% Cu. The following textile values were determined:

Example 2

Spinning was carried out in accordance with Example 1, but the polymer used consisted of 94.5% of acrylonitrile, 5% of methyl acrylate and 0.5% of sodium methallyl sulfonate. The relative viscosity of the polymer was 1.92. A spinning solution with 26% polymer in dimethylformamide was used, which was spun at a temperature of 80 ° C. The conditions for coagulation, washing and wet stretching corresponded to those of Example 1. The stretching on the hot rolls at 160 ° C. was chosen to be 1: 1.25. The concentration of the copper treatment bath and the temperature corresponded to those of Example 1. The fibers obtained showed good drawability for acid dyes with good whiteness. The copper content of these fibers was 3.2%, they had the following textile values:

Example 3

A spinning mass was spun according to Example 1 through a 300 hole nozzle. The nozzle bore diameter was in each case. 60 µm. A mixture of 61% dimethylformamide and 39% water at 50 ° C served as the spinning bath. The freshly spun threads were drawn off from the precipitation bath at a speed of 7 m / min, subjected to wet drawing at 99 ° C. of 1: 2.85 in a bath which consisted of 62% dimethylformamide and 38% water, and then with Wash water free of solvents at 80 ° C. After the washing process, the fiber sliver was squeezed to remove a large part of the water and passed through a trough which contained an aqueous solution of 29 g / l CuSO ₄ x 5 H ₂ O and 5.7 g / l of the sodium salt of hydroxymethanesulfinic acid * (residence time 1.5 sec.). This bath also contained the necessary preparation components. The solution was dosed in accordance with Example 1. After passing through the tub, the sliver was squeezed again and subsequently dried on 2 heating godets at 140 ° C., then subjected to drawing from 1: 1.14 to 2 heating godets at 160 ° C. and then from the last heated godet on a cold take-off device with a further drawing of 1: 1.9. The fibers obtained had a copper content of 1.6% and showed good dyeability with acid dyes. The measured textile values were _* Formula: _CH2 SO ₂ Na x 2 H ₂ ⁰

Example 4

A spinning according to example 3 was carried out. However, the treatment solution consisted of an aqueous solution of 50 g / l CuS0 ₄ x 5 H ₂ 0 and 4 g / l metallic copper powder. The treatment temperature in this case was 85 ° C. During the spinning period, care was taken to ensure that the content of metallic copper in the treatment bath was also kept constant. The fiber obtained had a copper content of 2.1% and good dyeability with acid dyes. The textile data of this fiber was

Example 5

Spinning was carried out in accordance with Example 1, but the anionic dye Acid Blue 41 (Color Index No. 62 130) was added to the CuS04 solution. The dye concentration was chosen so that a concentration of 20 g dye / l was maintained in the treatment bath.

The threads obtained were dyed deep blue. The dyed dye could no longer be removed, for example, by washing at 60 ° C.

Claims (7)

1. A process for the production of threads and fibers from polymers which consist of more than 50% by weight of acrylonitrile units and are produced by a dry or wet spinning process, characterized in that the thread strands or cables obtained during spinning, however, during the production process before the first drying or a first temperature treatment above 100 ° C are continuously treated with an aqueous solution containing copper (I) ions and the copper content in the strands or cables simultaneously or by subsequent heating to temperatures above about 60 ° C, preferably above about 100 ° C is fixed. 2. The method according to claim 1, characterized in that the copper (I) ion-containing solution has room temperature and the fixing of the copper content is carried out by a directly subsequent temperature treatment. 3. The method according to claim 1 or 2, characterized in that the copper (I) ion concentration of the treatment solution is 0.1 to 50 g / l, preferably 0.5 to 30 g / 1. 4. The method according to claims 1 to 3, characterized in that the thread strands or cables after the continuous treatment with a copper (I) ion-containing solution and extensive stripping and / or squeezing the excess solution first a temperature treatment above 60 ° C, preferably above 100 ° C, to be subjected to further washing processes, the finishing and the final drying. 5. The method according to any one of the preceding claims, characterized in that the copper (I) ion-containing solution is produced continuously by mixing approximately stoichiometric amounts of a copper (II) ion-containing solution with an aqueous solution containing a reducing agent or is refreshed. 6. The method according to claim 5, characterized in that as the solution containing copper (II) ions, a solution of copper (II) sulfate in water and as the solution containing the reducing agent, a solution of an aldehyde sulfoxylate, preferably the sodium salt of hydroxymethanesulfinic acid, in water is used. 7. The method according to any one of the preceding claims, characterized in that the spinning tow or strands prior to a first treatment at temperatures above 100 ° C or a first drying not only continuously with an aqueous solution containing copper (I) ions but simultaneously or are treated in a subsequent step with a solution of an anionic dye.