GB1567060A - High temperature dyeing of nitrogen-containing natural fibrous materials - Google Patents

Abstract

The dyeing is carried out in an aqueous bath and with dyes conventional for these fibres, beyond the boiling point and in the presence of formaldehyde and of a fatty acid amide of the general formula (I): <IMAGE> where R = C10-C20-alkyl or -alkylene, R1 and R2 = H, (-CH2-CH2-O)nH, -(CH2)1-4-N(R3)(R4 ) or <IMAGE> where R3 and R4 = H or C1-C4-alkyl and n = an integer. When dyed according to this process, wool and its mixtures with polyester show high colour strength properties without a loss of the typical qualities of wool (softness etc.) and with significant improvement in its tearing resistance.

Description

(54) HIGH TEMPERATURE DYEING OF NITROGEN CONTAINING NATURAL FIBROUS MATERIALS (71) We, AZIENDE COLORI NAZIONALI AFFINI ACNA S.p.A., of Largo Donegani 1/2, Milan, Italy, an Italian Company, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to a process for dyeing nitrogen-containing natural fibre, in particular wool, either alone or blended with synthetic fibres, in particular polyester, at high temperatures. An object of the invention is to protect the nitrogenous fibre from substantial degradation at the high temperature involved.

In particular, it is an object of the invention to permit the dyeing of blends, for instance 45/55 polyester/wool blends at a temperature as high as 1200C, without the wool suffering such damage as to render the quantity of the finished product materially inferior to that obtainable by conventional dyeing processes.

It is also an object of the invention to enable pure wool fabrics to be dyed at temperatures of the order of 115"C in timeperiods considerably shorter than those usually employed whilst obtaining quality characteristics not materially or at all inferior to those of the product dyed at boiling point.

Established processes for dyeing fabrics or yarns containing wool, either alone or blended with other synthetic fibres, are in general of two kinds, which differ from each other according to whether the dyeing is effected at boiling temperature or under pressure, generally at 1060C. It is also possible, in a third method, to dye at temperatures higher than 106"C, employing formaldehyde as a protective agent for the wool, but this has not found wide acceptance because the characteristics of softness typical of wool are deleteriously affected so as badly to affect the quality of the finished product.

The aforesaid two kinds of dyeing process as utilized for pure wool are substantially the same as regards the auxiliary products and dyestuffs employed.

In the case of polyester/wool blends, the difference between the two processes is more marked because other factors intervene. In fact there is present a synthetic fibre which usually, when alone, is dyed at temperatures of the order of 1300C. The presence of the wool compels the dyer to employ a dyeing method fit for wool and, therefore, temperatures preferably not exceeding 106"C. To do this it is necessary to use accelerators for the dyeing of the polyester fibre, known as carriers which, if suitable dyestuffs are chosen, permit dyeings of high intensity to be obtained. The amount of carrier required is the higher, the lower the dyeing temperature (in general about 3 g/t at 98 C and 2 g/ 1 at 1060C).

Another factor that differentiates between the two processes and militates in favour of the latter is the influence exerted by the temerpature on the tendency of many plastosoluble dyestuffs to dye wool to a greater or lesser degree. Such staining could impair the finished product's fastness to sunlight, to wet treatments and to cleaning. Generally, the higher the temperature, the less the wool portion is stained by the dye intended for the polyester. Furthermore, the higher the temperature, the less the total dyeing time and the better the exhaustion of the bath.

Specifically, when dyeing is conducted at, say, 1200C the dyestuff's migratory power is enhanced, leading to a reduction in the required dyeing time.

It should be mentioned that the use of the carrier involves some problems that it has not always been possible to solve. Such problems are: a. a high pollution degree of the environment and of the waste waters; b. formation of stains during the dyeing; c. high costs; d. lowering of the dyeings' fastness characteristics due to the difficulties met in the removal of the carrier from the dyed material; e. limited selection of the employable disperse dyes.

It is also an object of the invention to provide a process for dyeing a natural, nitrogen-containing fibrous material, in particular wool, which permits operation at temperatures higher than those usually employed, giving rapid exhaustion of the dyestuff whilst affording good penetration even into highly twisted materials and without materially or at all impairing the quality of the nitrogen-containing fabric and the uniformity of the dyeing.

Still another object of this invention is to provide a process for dyeing wool in blends with synthetic fibres, which permits operation in a single bath at such temperatures as not to require the use of carriers, whilst still achieving exhaustion of the dispersed dye employed for the synthetic fibre.

A further object of the present invention is to provide a process for dyeing wool/polyester, wool/polyamide, wool/acrylic, wool/modacrylic, and wool/vinylic blends.

Yet another object is to provide a process for dyeing silk and silk/polyester blends.

Still another object of this invention is to provide wool and blends thereof with synthetic fibres dyed in a wide range of shades exhibiting excellent general stability.

The invention consists in a process comprising the dyeing of natural, nitrogencontaining fibrous material or of blends thereof with synthetic fibre in an aqueous bath containing formaldehyde, an amide of a fatty acid as defined below, and a suitable dyestuff or mixture of dyestuffs under acidic conditions at a temperature higher than 100"C, but below that at which the wool suffers substantial damage.

Preferably, the bath is used at a pH of 4-5 and also preferably, the temperature is in the range 110-1200C.

The amides employed in the process of the present invention conform to the general formula R-CO-NR1R2 wherein R is an alkyl or alkenyl radical of 10-20 carbon atoms, and R1 and R2 are variously H, (-CH2CH2O)nH, (-CHCH3-CH2O)nH where n is an integer, or (-CH2)m-NR3R4 where m is 1, 2, 3 or 4 and R3 and R4 are variously as already defined for Rl and R2 or alkyl of 1-4 carbon atoms.

Preferred amides include the amides of saturated or unsaturated fatty acids with monoamines, such as the mono- and diethanolamides of lauric acid or of coconut acid; or products of condensation of amides of saturated or unsaturated fatty acids with ethylene oxide, such as, for example, laurylamide or coconutamide condensed with 4 moles of ethylene oxide; and amides of fatty acids, either saturated or unsaturated, with substituted polyamines, such as, for instance, the amino-ethylethanolamide of lauric acid.

The process of the present invention can be carried out with conventional dyestuffs suited to the dyeing of wool and of synthetic fibres, in particular polyester.

Dyestuffs particularly suitable for dyeing wool includes the premetallized dyestuffs 1:2 and the solid milling dyestuffs available under the trade names Stenolana and bright Stenolana of the present Applicants, but excellent results have also been achieved with premetallized dyestuffs 1:1 and acid ("Stenamina", "Novamina" and "Fast Novamina" of the present Applicants). To dye polyester in a blend with wool it is possible to employ a wide selection of dispersed dyes (wider than that usually employable at 106"C with carriers), for example a selection of dyestuffs belonging to the series "Microsetile" and "Tersetile" of the present Applicants.

Dyestuff mixtures particularly suitable for dyeing wool/polyester blends include those based on premetallized and milling dyestuffs for the wool and based on dispersed dyes for the polyester, such as a mixture of "Stenolana" and "Tersetile". In one convenient mode of carrying the invention into effect, the dyeing process is conducted as follows: a.Dyeing pure wool A suitable amount of water at 50"C is loaded with the material to be dyed (fabric or yarn) in a closed apparatus capable of standing temperatures and corresponding pressures up to 1300C; this bath is then treated successively with the following: 1.5 - 2 g/l of 30% formaldehyde, 2 - 3% (on fibre weight) of lauryldiethanolamide, 2 - 3% (on the fibre weight) of acetic acid up to pH 4 - 5, and a dyestuff for wool, in an amount sufficient to dye the yarn or fabric.

The temperature is then raised rapidly up to 115 - 120"C, maintaining such temperature for from 2 to 45 minutes. The dwell time at the maximum temperature depends on the intensity of the dyeing and on the type of material.

The pure wool fabric or yarn so dyed exhibits in general mechanical and physical properties thoroughly comparable with those of the fabrics or yarns conventionally dyed, and surprisingly superior to those of fabrics or yarns dyed under the same conditions but without utilizing the diethanolamide.

b. Polyester/wool A suitable amount of water at 500C is loaded with the material to be dyed (fabric or yarn) in a closed apparatus, suitable for temperatures and corresponding pressures up to 1300C; the following materials are then added, successively, to the bath: 1.5 - 2 g/l of 30% formaldehyde; 2 - 3% (on the fibre weight) of lauryldiethanolamide 2 - 3 (on the fibre weight) of acetic acid up to pH 5 1.5 - 2 g/l of ammonium sulphate; dyestuff for the polyester, in an amount sufficlent to dye the polyester; and dyestuff for the wool, in an amount sufficient to dye the wool.

The temperature is rapidly raised to 80 85"C and then, in the course of 20 minutes, up to 1200C. This temperature is held for from 30 to 60 minutes, depending on the intensity of the dyeing and on the type of material being dyed, as well as on the particular dyestuffs. The dyed fabric or yarn exhibits in general mechanical and physical characteristics thoroughly comparable with those of the same fabrics or yarns conventionally dyed and surprisingly superior to those of the fabrics or yarns dyed under the same conditions but without using the lauryldiethanolamide.

The following specific examples further illustrate how the invention may be carried into effect. The percentages given, except of course in the case of formaldhyde strength, are by weight based on the material being dyed.

EXAMPLE 1 An apparatus for the pressure dyeing of fabrics was charged with 100 kg of pure wool gabardine weighing 500 g/linear meter. The bath ratio was 1: 20, the material feed speed 100 m/min. At a temperature of 50"C there were added: 1.5 g/l of 30% formaldehyde and, after 5 minutes, 2% of lauryldiethanolamide, acetic acid to bring the pH to 5, a levelling agent, 3% of "Yellow Stenolane GL" (C.I. Acid Yellow 140), 0.8%of "Red Stenolana BL" (C.I. Acid Red 271) and 0.6 % of "Grey Stenolana BL" (C.I.

Acid Black 133). The temperature was brought to 1150C in the course of 25 minutes.

After 40 minutes the bath was cooled down and the dyed material was rinsed in the conventional manner. The dyeing appeared perfectly uniform and well penetrated. An examination of the mechanical characteristics of the fabric dyed at 1150C in comparison with a fabric of the same quality dyed at 98"C indicated only slight differences and, in the opinion of experts, the "handle" of the fabric dyed at 115"C was comparable with that of the fabric dyed at 980C.

EXAMPLE 2 An apparatus for the pressure dyeing oaf fabrics was charged with 100 kg of polyester/wool gabardine weighing 450 g/linear m. The bath ratio was 1: 20 and the material feed 110 m/min. At a temperature of 50"C, 2 g/l of 30% formaldehyde were added and, after 5 minutes, 2% of coconut diethanolamide, acetic acid to bring the pH to 5, a levelling agent and 3% of "Brown Tersetina SG" (a mixture of dispersed dyes and premetalized dyes). The temperature was brought to 120"C in the course of 45 minutes and then held for 30 minutes, whereupon the bath was cooled and the dyed material was rinsed conventionally. The fabric appeared uniformaly dyed.

An examination of the mechanical characteristics of the fabric dyed at 120"C as compared with a similar fabric dyed at 106"C did not indicate any difference and the "handle" of the fabric dyed at 1200C was, according to expert opinion, equal to or better than that of the fabric dyed at 106"C.

EXAMPLE 3 An apparatus for pressure dyeing yarn was charged with 100 kg of a polyester/wool 1/24 yarn. The bath ratio was 1:15. At a temperature of 50"C, 2 g/l of 30% formaldehyde were added and, after 5 minutes, 2% of lauryl monoethanolamide previously dissolved in alcohol, acetic acid to bring the pH to 5, a levelling agent and 2%of "Blue Tersetina SB" (a mixture of dispersed dyes and fast milling dyes).

The temperature was rapidly raised to 80"C and then, in the course of 30 minutes, to 1200C. This temperature was held for 30 minutes, whereupon the bath was cooled down and the dyed material was rinsed conventionally. The fabric exhibited a uniform dyeing and an examination of the mechanical characteristics in comparison with those of similar yarn dyed at 106"C did not indicate a difference of any kind.

The levelling agents referred to in the examples are compounds added to the dye bath to enhance the uniformity of the dyeing.

They are commercially available and are generally constituted by mixtures of anionic sulphated, and non-ionic ethoxylated, surface active agents.

WHAT WE CLAIM IS: 1. A process for dyeing natural nitrogen-containing fibrous material in an aqueous bath under acidic conditions with a suitable dyestuff, in which the dyeing is effected at a temperature above 100"C, but below that at which the material suffers substantial damage, in the presence of formaldehyde and of at least one amide as hereinbefore defined.

2. A process according to claim 1, in which the nitrogen-containing natural material is wool.

3. A process according to claim 1 in which a synthetic fibrous material is also present, and the death also includes a suitable dyestuff therefor.

4. A process according to claim 3 in which a wool/polyester or a silk/polyester

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (9)

**WARNING** start of CLMS field may overlap end of DESC **. 1300C; the following materials are then added, successively, to the bath: 1.5 - 2 g/l of 30% formaldehyde; 2 - 3% (on the fibre weight) of lauryldiethanolamide 2 - 3 (on the fibre weight) of acetic acid up to pH 5 1.5 - 2 g/l of ammonium sulphate; dyestuff for the polyester, in an amount sufficlent to dye the polyester; and dyestuff for the wool, in an amount sufficient to dye the wool. The temperature is rapidly raised to 80 85"C and then, in the course of 20 minutes, up to 1200C. This temperature is held for from 30 to 60 minutes, depending on the intensity of the dyeing and on the type of material being dyed, as well as on the particular dyestuffs. The dyed fabric or yarn exhibits in general mechanical and physical characteristics thoroughly comparable with those of the same fabrics or yarns conventionally dyed and surprisingly superior to those of the fabrics or yarns dyed under the same conditions but without using the lauryldiethanolamide. The following specific examples further illustrate how the invention may be carried into effect. The percentages given, except of course in the case of formaldhyde strength, are by weight based on the material being dyed. EXAMPLE 1 An apparatus for the pressure dyeing of fabrics was charged with 100 kg of pure wool gabardine weighing 500 g/linear meter. The bath ratio was 1: 20, the material feed speed 100 m/min. At a temperature of 50"C there were added: 1.5 g/l of 30% formaldehyde and, after 5 minutes, 2% of lauryldiethanolamide, acetic acid to bring the pH to 5, a levelling agent, 3% of "Yellow Stenolane GL" (C.I. Acid Yellow 140), 0.8%of "Red Stenolana BL" (C.I. Acid Red 271) and 0.6 % of "Grey Stenolana BL" (C.I. Acid Black 133). The temperature was brought to 1150C in the course of 25 minutes. After 40 minutes the bath was cooled down and the dyed material was rinsed in the conventional manner. The dyeing appeared perfectly uniform and well penetrated. An examination of the mechanical characteristics of the fabric dyed at 1150C in comparison with a fabric of the same quality dyed at 98"C indicated only slight differences and, in the opinion of experts, the "handle" of the fabric dyed at 115"C was comparable with that of the fabric dyed at 980C. EXAMPLE 2 An apparatus for the pressure dyeing oaf fabrics was charged with 100 kg of polyester/wool gabardine weighing 450 g/linear m. The bath ratio was 1: 20 and the material feed 110 m/min. At a temperature of 50"C, 2 g/l of 30% formaldehyde were added and, after 5 minutes, 2% of coconut diethanolamide, acetic acid to bring the pH to 5, a levelling agent and 3% of "Brown Tersetina SG" (a mixture of dispersed dyes and premetalized dyes). The temperature was brought to 120"C in the course of 45 minutes and then held for 30 minutes, whereupon the bath was cooled and the dyed material was rinsed conventionally. The fabric appeared uniformaly dyed. An examination of the mechanical characteristics of the fabric dyed at 120"C as compared with a similar fabric dyed at 106"C did not indicate any difference and the "handle" of the fabric dyed at 1200C was, according to expert opinion, equal to or better than that of the fabric dyed at 106"C. EXAMPLE 3 An apparatus for pressure dyeing yarn was charged with 100 kg of a polyester/wool 1/24 yarn. The bath ratio was 1:15. At a temperature of 50"C, 2 g/l of 30% formaldehyde were added and, after 5 minutes, 2% of lauryl monoethanolamide previously dissolved in alcohol, acetic acid to bring the pH to 5, a levelling agent and 2%of "Blue Tersetina SB" (a mixture of dispersed dyes and fast milling dyes). The temperature was rapidly raised to 80"C and then, in the course of 30 minutes, to 1200C. This temperature was held for 30 minutes, whereupon the bath was cooled down and the dyed material was rinsed conventionally. The fabric exhibited a uniform dyeing and an examination of the mechanical characteristics in comparison with those of similar yarn dyed at 106"C did not indicate a difference of any kind. The levelling agents referred to in the examples are compounds added to the dye bath to enhance the uniformity of the dyeing. They are commercially available and are generally constituted by mixtures of anionic sulphated, and non-ionic ethoxylated, surface active agents. WHAT WE CLAIM IS:

1. A process for dyeing natural nitrogen-containing fibrous material in an aqueous bath under acidic conditions with a suitable dyestuff, in which the dyeing is effected at a temperature above 100"C, but below that at which the material suffers substantial damage, in the presence of formaldehyde and of at least one amide as hereinbefore defined.

2. A process according to claim 1, in which the nitrogen-containing natural material is wool.

3. A process according to claim 1 in which a synthetic fibrous material is also present, and the death also includes a suitable dyestuff therefor.

4. A process according to claim 3 in which a wool/polyester or a silk/polyester

blend is dyed.

5. A process according to any preceding claim in which the dyeing temperature is 110 - 1200C.

6. A process according to any preceding claim in which the pH of the dye bath is 4 - 5.

7. A process according to any preceding claim in which the amide used is one of thos hereinbefore specifically referred to.

8. A process according to claim 1, substantially as set forth in any of the foregoing general or specific examples.

9. Yarns and fabrics of wool or silk and of blends thereof with polyester, when dyed according to any of the foregoing claims.