DE2063179A1 - Process for dyeing tow in the hydrated state - Google Patents

Description

CIBA-GEIGY AG, Basel / Switzerland

Process for dyeing tow in the hydrated state

Fibers made of polyacrylonitrile are produced according to the so-called dry spinning process, in which the fiber is produced from a solution of the polymer in organic solvents by evaporation of the solvent, or according to the so-called wet spinning process, in which the fiber is precipitated in aqueous solution with the addition of electrolytes is received. In the so-called wet spinning process, following the actual fiber formation process (spinning process), the fiber is first subjected to a few washes and then to a stretching process to orient the macromolecules before it is dried. In this “swollen” gel-like state, the fiber is able to absorb dyes to a particularly high degree, for example from aqueous liquor. Dyeing in this state can therefore take place under considerably milder conditions than are required for dyeing the same, but dried fiber after spinning. The result is therefore in the dyeing of tow in a hydrated state energy and time saving, · in Furthermore, a drying process can be saved.

The previously known methods for dyeing fibers in the gel-like state essentially consist in bringing the fibers into contact with the dye solution either on a padder or in a simple dye bath

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and then washed hot. Because the fiber is constantly dyed from the dye bath in a continuously running process removed, in the known processes for achieving a certain color tone, specific apparatus measures are required required, which guarantee that the dye concentration in the dyebath is kept constant. As such measures are e.g. the measurement of the dye concentration as well as a control of the replenishment of the dye solution, e.g. via an electronic control system, inevitable. Becomes a mixture of dyes used for coloring, as is generally the case, the individual dyes must be used in accordance with their coloring behavior be replenished separately, which requires a separate control ^ of the individual dye solutions. Such control systems are very complicated and expensive and often tend to cause the tax variable to oscillate.

It has now surprisingly been found that in Fibers produced by wet spinning processes, in particular polyacrylonitrile tow can dye continuously in the hydrated gel state in a simple manner if the fiber or the After fiber formation, the fiber strand is moved through a counter-flowing dye solution or suspension without prior drying.

The countercurrent principle is known, for example, in so-called cascade washers in fiber production.

The application of Gegenstr'omprinzips for dyeing tow w when hydrated is very economical. Furthermore, this enables the fibers mentioned to be dyed in a certain color tone and in degrees of exhaustion of almost 100% using the continuous process in a simple manner without any complex electronic control.

The process may be carried out for example in a device is characterized which through a series of communicating Gefässenj a leading through these vessels transport device for the fiber strands - _t a feed device for dye solution mündetf in the relative last of the transport direction Gefass wherein the vessels are equipped with baffles which direct the dye solution in a countercurrent to the transport path of the fiber strands.

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Such a system is explained in more detail with reference to the drawing, for example, j it shows

1 shows an exemplary embodiment of the device for the inventive Carrying out the countercurrent dyeing in a schematic sectional view and FIG. 2 shows a section along the line II - II in FIG. 1.

The dyeing unit shown consists essentially of a number of vessels S ,, S2 ... S, a transport device G, H for fiber strands F leading through these vessels, a mixer L for the preparation of the dye solution and a metering pump K. The outlet of the mixer is connected to the last vessel S in relation to the transport direction via the dosing pump. The vessels S, S, ... S ₁ communicate via over-

n n-l J.

run D together. Baffles C are installed in the vessels, which force the dye solution in a countercurrent to the transport path. The first vessel is preferably overflow-like Outflow E provided. M denotes a double jacket for a heating medium for thermostatting the row of vessels.

The functioning of this dyeing unit is as follows: The dye solution mixed in the storage mixing tank L is replenished by the metering pump K, possibly after previous dilution Point A of the last vessel of the dyeing unit promoted. The solution is forced through the baffles C, in the countercurrent direction to flow downwards via point B and then flow again at point D from the last vessel into the penultimate overflow. the The liquor now passes through all the vessels in the same way, in order to finally exit the first vessel at point E. " The fiber material, which has undergone the usual treatment after the spinning process, comes from point F via the guide rollers G and H and is immersed in the first vessel. The residence time within a vessel depends on the one hand on the Speed of fiber transport and on the other hand after the Dimensions of the individual vessels. It should be in the order of magnitude of approx. 0.1 to 30 seconds. The fiber is so with the least concentrated dye solution in contact

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brings, absorbs a certain amount of dye from this, occurs then into the next vessel over, where the dye concentration is higher. In this way, the fiber is in contact with the fresh dye solution in the η-th vessel at the end, so that after • the state of equilibrium has established itself, the depth of color of the emerging material at point I is constant. The guide rollers G and H ropes must be constructed in such a way that the tow passes through the individual vessels as widely as possible so that the Penetration of the dye solution into the tow is optimal.

The depth of color is controlled on the one hand by varying the concentration of the dye solution in the mixing tank L, on the other hand by varying the amount of the solution added by the metering pump K. With a constant concentration in the tank L and a constant metering rate, equilibrium concentrations arise in the individual vessels, which from the Remove vessel (s) to vessel (n-1 ... 1). The optimum setting is reached when the concentration of the dye emerging at point E. solution is equal to or at least approximately zero, since in this way almost complete utilization of the dye is achieved. The time it takes to reach equilibrium depends on the size of the individual vessels; the smaller the volume of the vessels, the shorter it is. Since the ψ speed of the dyeing process and the achieved fiber equilibrium concentrations depend on the temperature of the dye liquor, it is advantageous to surround the entire dyeing unit with a thermostatic jacket M. For carrying out the coloring of hydrated polyacrylonitrile tow to a temperature ranging between 20 and 70 ⁰ C is to be maintained.

The advantages of the new process described are that the dye used is practically fully utilized and that there is no oscillation of the color strength of the material exiting at I, as is the case with systems based on a measurement of a variable and a control derived therefrom (post-dosing) arises. In the further will

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circumvented the problem of ending uniqueness by adding each part of the Fiber material at the end of the »dyeing process with fresh dye solution is brought into contact.

According to the invention, the dye liquors customary in practice can be used be used. They are appropriately prepared in such a way that that the dye is dissolved or dispersed in water and the dye liquor obtained with acid and / or a buffer salt on the sets the desired pH value.

According to the invention both disperse dyes, as anionic and especially cationic dyes can also be used. The dyes can belong to any class.

The disperse dyes which can be used according to the invention are used especially azo dyes, as well as anthraquinone, nitro, methine, styryl or azostyryl dyes.

As anionic ones which can be used in the process according to the invention Dyes are both so-called acidic wool dyes and nouns dyes of any class, their Like the alkali or ammonium salts of dyestuff sulfonic or dyestuff carboxylic acids, the coloring agent in the anion is, in particular, metal-free or metallized sulfonated mono- or disazo dyes, which also include formazan dyes, whose chromium, cobalt, nickel and copper complexes, as well as sulfonated anthraquinone, nitro and phthalocyanine dyes.

Cationic dyes which can be used according to the invention are advantageously the salts and metal halides which are readily available industrially, for example zinc chloride double salts of the known basic dyes. It is, for example, onium groups containing thiazines, oxazines, diphenylmethanes, triphenylmethanes, rhodamines, azo and anthraquinone dyes, preferably monoazo, methine, azomethine and anthraquinone dyes, and ammonium groups are to be mentioned as the onium groups in the first place.

The following examples illustrate the invention * Therein the temperatures are given in degrees Celsius.

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Examples

Dyeings are carried out in a dyeing unit, which consists of 5 successive elements S to S ₁ - which are constructed in such a way that they allow an immersion time of 0.7 seconds / element at a tow speed of 0.5 m / sec. This corresponds to an immersion length of 0.35 m / element. Such an assembly is shown in Fig. 1, but the individual elements S-. to S, - are arranged in a cascade.

The dyeing unit at G is continuous with polyacrylonitrile tow charged, which is made from a solution of polyacrylonitrile in sodium thiocyanate by the wet spinning process t manufactured and stretched at 95 ° as is customary in technology, washed but not dried. The water content of the tow is increased by squeezing off the excess water about 1707o of the dry weight reduced. The amount of cable entering the dyeing unit at G is given in the table

An aqueous solution of a dye, the composition of which is given in Table II, is mixed in the storage tank L. and with the metering pump K with a constant metering volume in a T-shaped mixing element with a likewise constant The amount of water held is mixed and added to the element Seg at A, taking care that the dye solution is distributed over the entire width of the apparatus.

The tow, colorless at G, is successively colored in the individual elements S-j to Sc and leaves at I in colored state the aggregate.

The still adhering dye solution is removed by two nip rollers and discarded. The colored tow is then briefly rinsed in hot water and then dried. The concentration of the dye solution increases from element Sr to S-, slowly from, se that the dye solution at E the plant in colorless to almost colorless state.

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If you start the operation of the system in such a way that all elements are first filled with water, it will take a few minutes a state of equilibrium with regard to the dye concentration in the individual elements is reached. After reaching the In the state of equilibrium, the color of the colored cable remains at a constant dosing rate and at a constant one Dosing concentration constant even over a longer period of time.

The following table 1 shows the constitutions of the dyes used:

TABLE I.

Dye of the formula

- N = N

Cl "

II dye of the formula

CHo O

I J Il

HoC-N-CH ₀ -CJ ι L

3 y

Cl "

III dye of the formula

- N

N-CH ₂ CH ₂ OH C ₂ H ₅

ZnCl.

IV dye of the formula

S. ^Χ Ν ^

CH ₂ CH ₂ -H [JS

Cl

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V dye of the formula

It

CH-CNP VN = N 3 η V = /

CH,

VI dye of the formula

O NHCH,

j 1 ^:

NHCH ₂ CH ₂ OH

VII dye of the formula

Cl

NH

- Ν = N

ο ^Η0 ~ \\ //

Cl ^S0 3 ^Na

VIII dye of the formula

NH ₀ SO ₂ ν

N =

HO

SO ₃ Na

IX dye of the formula

NaO ₃ S

NaO ₃ S

SO ₃ Na

SO ₃ Na

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The following Table II gives the components used in Examples 1 to 9, their amount and the dyeing conditions again. At the end of the example, the hue of the polyacrylonitrile fiber dyed according to the invention is given in each case.

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TABLE II

temperature Examples 1 I. 2 3 dye Dosing amount, stock solution 43 g / l I. I. Concentration of the stock solution Dosage amount, water 2 g / l 13 g / l 43 g / l Acetic acid, conc. Water temperature 2 g / l 2 g / l 2 g / l Sodium acetate, conc. Temperature in element S - S 4.6 2 g / l 2 g / l PH PAC tow quantity 30 ^e C 4.6 * .6 Relative dye concentrations 110 ml / min 30 ⁰ C 30 ⁰ C trations * in the same 1700 ml / min 110 ml / min 110 ml / min weight condition 25 ⁰ C 1700 ml / min 850 ml / min Element S
5 36-25 ⁰ C 50 ⁰ C 50 ⁰ C Element S 1-30 g / min 48-42 ° C 48-42 ⁰ C Element S 430 g / min 430 g / min Element S Element S Pinched Solution ' 80 % Degree of exhaustion 69 sweet 77 % Color depth achieved ** 28 % 44 f 42 <f> Hue of the stained 10 % 25 Ji 18 pounds Polyacrylonitrile fiber 4 * 12 % 7 * 1.6 % 1% 3 * 95 % 0.2 Ji 0.5 each 1.05 si 93 each 965g dark red 1.02 f I.06 % dark red dark red

Legend; Conc, at the inflow = lOOjtf

* · Dye based on the weight of the dry fiber

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Table II continued

temperature Examples k 5 6th Dosing amount, stock solution II II: 1.5 g / l III: 4.3 g / l dye Dosage amount, water I: 3.8 g / l IV: 0.12 g / l Water temperature III: 6.1 g / l Temperature in element S - S l6o g / i _ Concentration of the stock solution PAC tow quantity 3 g / l 2 g / l 6 g / l It s igs sura, conc. Relative dye concentrations 3 g / l 2 g / l 2 g / l Sodium acetate, conc. trations * in the same Ί.6 3.4 3.7 PH weight condition 35 ° C 30 ⁰ C 22 ^e C Element S 260 ml / min 100 ml / min 130 ml / min Element S 850 ml / min 800 ml / min 800 ml / min Element S 30 ⁰ C approx. 25 ⁰ C approx. 25 * C Element S 38-32 ⁰ C 38-26 ° C 37-25 ° C Element S t30 g / min ^ 30 g / min 430 g / min Squeezed solution Degree of exhaustion Color depth achieved ** Hue of the stained 92 % - - Polyacrylonitrile fiber 56 % - - 35 f - - 18 % - - 8th* approx. 2 Ji 2 Ji 2 Λ Ji approx. 0.2 Ji 2 * 91 H. 98 % 98 t * Af 0.2k f> 0.13 Ji yellow Gray blue

Legend : * Conc. At inflow = 100 Ji

** Dye based on the weight of the dry fiber

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Table II continued

■ dye temperature Examples 7th 8th 9 Dosing amount, stock solution V: 35 g / l VII: 88 g / l VIII: 12.6 g / l Concentration of the stock solution Dosage amount, water VI: 7 g / l IX: 62 g / l Acetic acid, conc. Water temperature _ _ Sodium acetate, conc. Temperature in element S - S
1 5 - - - PH PAC tow quantity - - - Relative dye concentrations 6.8 6.4 6.4 trations * in the same 48 ° C 25 ⁰ C 55 ⁰ C weight condition 165 ml / min 110 ml / min 60 ml / min Element S 700 ml / min 1250 ml / min 1700 ml / min Element S 55 ° C 30 ⁰ C 55 ° C Element S 42-53 ⁰ C 35-28 ° C U3-54 ^O C ' Element S 430 g / min 430 g / min 430 g / min Element S Squeezed solution Degree of exhaustion <
Color depth achieved ** ' - 66% - Hue of the stained - kl% - Poly-acrylonitrile fiber
• - $ 25 - - 16 % - 11 % - about $ 6 k% approx. 8 % approx. 86 # 88 % approx. 84 <f> 1.4 # I.96 ft 0.87 % green Red orange

Legend ; * Conc. At inflow = 100 {6

** Dye based on the weight of the dry fiber

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te »-

The present process is also eminently suitable for the continuous optical brightening of fibers produced by the wet spinning process. According to the invention, dispersible, anionic and, in particular, cationic optical brighteners can be used
be used. You can belong to a wide variety of classes. Particularly brilliant lightening effects are obtained with
anionic compounds, which are derived from the class of the stilbenes, and with cationic compounds, which are derived from the class of the coumarins.

The following two optical brighteners were used in Examples 10 and 11 of Table III below. the
Components used, their amounts, the treatment conditions and the lightening effect achieved are shown in Table III
listed. Otherwise, the procedure was as described in Example 1
procedure.

X Optical brightener of the formula

(CH ₃ -CH ₂ ) ₂ -N

(CH ₃ ) 3-N-CH ₂ -CH ₂ -CH ₂ -NH

0-SO ₃ CH ₃

XI Optical brightener of the formula

HO ₀ SZ ^ -HN

HO-CH ₂ -CH ₂ -N

SO ₃ H

~ NH - <Q>

-CH = CH

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Ii

TABLE III

temperature BeisDiele 11 Optical brightener Dosierrcenge, Starnmlösung 10 XI Concentration of the Stanun solution Dosage amount, water X 5 g / l Acetic acid, mark. Water temperature 4 g / i - Sodium acetate, conc. Temperature in element S - S 0.5 g / i - PH PAC spun cable tight 0.5 g / l 6.2 Relative concentrations * des 4. 6 40 ° C optical brightener in the same 30 ° C 140 ml / min weight condition 110 ml / min 1400 ml / min Element S 1700 ml / min 50 ⁹ C Element S 25 ⁰ C 48-42 ⁰ C Element S 36-25 ^o C 430 g / min Element S 430 g / min Element S Squeezed solution > Degree of exhaustion $ 58 Achieved white effect ** 56 Jf $ 42 treated polyacrylonitrile fiber 36 % 25 y? 20th % 7.2 Jt 6% 2.6 % 2 % <0.2 J5 <0.1 Ü 96 Ji 98-Ji 0.15 Ji 0.1 % White, ' knows lightened lightened

Legend; * Conc. At inflow = 100 $

** Optical brightener based on the weight of the dry fiber

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Claims (1)

Claims Process for the continuous dyeing of wet spinning no manufactured fibers, in particular for the continuous dyeing of polyacrylonitrile tow in the hydrated state, characterized in that the fiber or the fiber strand after fiber formation without prior drying by a counter-flowing dye solution or suspension is moved. 2. The method according to claim 1, characterized in that the concentration of the dye solution or suspension on that Location of where the fiber leaves the dye solution and / or the relative speed of the fiber to the dye solution like this be set / is that at the point where the fiber enters the dye solution, the dye solution a Has concentration equal to or at least approximately zero. 12/8/70 Ju / sh 109829/1134 Blank page