DE1669418A1 - Process for coloring polyamides - Google Patents

Description

Process for dyeing polyamides The invention is a Process for spin-dyeing molded articles produced by the melt-spinning process Made from linear, synthetic polyamides.

It is known to dye synthetic polyamides in bulk, whereby inorganic or organic dyes or pigments can be used. Conditional Due to the high melting temperature of the polyamides, the choice of dyes is very great limited. A range of metal complexes of azo dyes and phthalocyanine metal complexes have already been proposed. However, durability, lightfastness and color depth leave behind left to be desired, since with some dyes an increasing sensitivity with with increasing concentration. Of inorganic color pigments can be practical only ultramarine, cadmium sulfide, iron oxide and chromium oxide are considered for spin dyeing to be pulled. Polyamide chips are usually made by treating them with dye solutions or dyestuff dispersions and, after drying, by the melt spinning process spun into threads. There is no continuity in this process and at the same time an increased expenditure on equipment is required.

A process has now been found for spin-dyeing formed structures made of linear, synthetic polyamides by the melt-spinning process by means of anthraquinone dyes which are soluble in polyamide, which is characterized in that anthraquinone dyes of the formula wherein R is hydrogen, methyl or the group R is hydrogen or the -S03Na group and R2 is hydrogen, the group means where A is a linear or branched alkyl radical, homogeneously distributed in part of the polyamide to form a dye concentrate, this dye concentrate is mixed with the majority of the polyamide and then this mass is melt-spun.

It was found that these dyes are surprisingly stable and lightfast at the given process temperatures. The following anthraquinone dyes are suitable: Form 1 shade 0 NH 2 NH2 0 S03Na NaSO ii blue 0 NH blue H 0 1 c2 r O NH-O-CH3 groin 0 NH-O-CH3 The color concentrates are produced in such a way that they preferably contain 5-30% by weight of dye. To prepare them, the dye powder can be mixed with a polyamide granulate and the mixture can be homogenized in a heated extruder, the color concentrate melt advantageously being processed into granulate. In the case of particularly temperature-sensitive dyes, the processing temperature in the extruder can be reduced considerably by using polyamides with a reduced molecular weight or by using mixed polyamides.

In a particular embodiment of the method, the dye or the dye mixture or a dye solution, in the Dye in a solvent compatible with polyamide, e.g. B. Xthylglycol, is dissolved, with the exclusion of air in a previously produced polyamide or mixed polyamide melt stirred in, the solvent evaporating again when a dye solution is used and the color concentrate melt, which is homogeneous after the dye has dissolved processed into granules. In the production of polyamide or mixed polyamide melt matting and / or color pigments can also be used.

The dye concentrate granules can either be mixed with ordinary Spun polyamide granulate or a continuously produced polyamide melt be added via a melting and metering device before spinning.

Generally there are dye contents in the shaped articles of about 0.01-2.0% required. The dye concentrates can also be mixed with matting or Color pigment concentrates can be used.

Before the polymerization, the starting materials can also contain coloring and / or Matting pigments as well as anti-aging agents, viscosity stabilizers, etc. can be added.

By spectrophotometric absorbance measurement of the dye concentrate solution in cresol in comparison with the dye solution it can be demonstrated that under the mild processing conditions at 200 ° C even after a residence time of 6 hours in no detectable dye degradation has occurred in the mixed polyamide melt.

Example 1: Preparation of a dye concentrate in an extruder 15 parts by weight of an anthraquinone dye of the formula are mixed with 85 parts by weight of polyamide 6 granules (rel. Viscous.

1 g / 100 ml in cresol = 2.70) and mixed in an extruder at 25 ° C to a homogeneous melt and then processed into granules. Used if a polyamide with a solution viscosity of 2.0 is used, the processing temperature be reduced to about 220 ° C.

B e i 9 p i e l 2: Production of a dye concentrate in an autoclave In a stirred autoclave made of stainless steel, a mixed polyamide is used in a known manner 6/66 85% by weight / 15% by weight by polycondensation of corresponding proportions of caprolactam and E ndiammonium -adipat produced at 250 ° C under pressure. To before releasing the pressure, the temperature of the mixed polyamide melt is reduced to approx. 200 OC and sets an anthraquinone dye according to Example 1 with exclusion of air added so that the color concentrate melt contains 15 wt .-% dye. After about one hour, the dye has distributed homogeneously in the melt. The processing granules can be made by a dry or wet spinning process.

By increasing the amount of dye added, a 20% by weight Prepare concentrate containing coloring agent.

B e i 8 p i e l 3: Production of dyed threads in one on 260-270 ° C heated spinning apparatus, which is equipped with a mixing roller, is a Mixture of 6, 7 parts by weight of 15% color concentrate (prepared according to Example 1 or 2) and 93.3 Ge - parts of polyamide 6 granules to form deep blue colored threads with a Final titre of 90/25 the spun. The light, washing, sweat, chlorine, rubbing, Dry cleaning, ironing and acid fastness of the threads is very good.

Using a mixture of 0.67 parts by weight of color concentrate and 99.4 parts by weight of polyamide granules, this gives light blue colored threads with corresponding good coloristic fastness properties.

Claims (2)

Claims: 1. A process for the spin-dyeing of molded structures produced by the melt-spinning process from linear, synthetic polyamides with the aid of polyamide-soluble anthraquinone dyes, characterized in that anthraquinone dyes of the formula wherein R is hydrogen, methyl or the group Ri is hydrogen or the -SO3Na group and R2 is hydrogen, the group or means where A is a divalent linear or branched alkyl radical, homogeneously distributed in part of the polyamide to form a dye concentrate, this dye concentrate is mixed with the majority of the polyamide and then this mass is melt-spun. 2. The method according to claim 1, characterized in that 0.1 up to 20% by weight of concentrate, based on the total amount of b * to be spun, clogs.