KR102388706B1 - Polyamide fibers with improved dyeing properties, methods for obtaining such fibers and polyamide articles made therefrom - Google Patents

Abstract

The present invention relates to polyamide fibers having improved dyeing properties. Polyamide fibers are suitable for low temperature dyeing and shorter dyeing cycles. The present invention also discloses a method for obtaining such fibers. Polyamide fibers are obtained by blending at least polyamide 5.X, wherein X is an integer from 4 to 16, with an aliphatic polyamide during melt-spinning extrusion of polyamide fibers. Blended polyamide fibers and articles made therefrom can be dyed at temperatures lower than conventional boiling temperatures, and the dyeing time is half that of a conventional dyeing cycle. Dyed polyamide fibers and articles also exhibit improved fastness to washing and perspiration.

Description

Polyamide fibers with improved dyeing properties, methods for obtaining such fibers and polyamide articles made therefrom

The present invention relates to polyamide fibers having improved dyeing properties. Polyamide fibers are suitable for low temperature dyeing and shorter dyeing cycles. The present invention also discloses a method for obtaining such fibers. Polyamide fibers are obtained by blending at least polyamide 5.X, wherein X is an integer from 4 to 16, with an aliphatic polyamide during melt-spinning extrusion of polyamide fibers. Blended polyamide fibers and articles made therefrom can be dyed at temperatures lower than conventional boiling temperatures, and the dyeing time is half that of a conventional dyeing cycle. Dyed polyamide fibers and articles also exhibit improved fastness to washing and perspiration.

Commercial interest in polyamides based on fibers and yarns, especially used in textile products such as underwear, sportswear, leisure wear and nightwear, has been driven by ease of care, quick drying properties, high durability, excellent physical properties, Due to their advantages in these fields, such as abrasion resistance, balanced moisture absorption, good elasticity, lightness, comfort and softness, they are widely increasing.

Polyamide, also known as nylon, is a linear condensation polymer composed of repeated primary bonds of amide groups. Polyamide fibers are generally made by melt-spinning extrusion and are available in staple fiber, tow, monofilament, multifilament, flat or texturing forms. Polyamides are semi-crystalline polymers. The amide group -(-CO-NH-)- provides hydrogen bonding between the polyamide intermolecular rings, which has high strength at high temperatures, toughness at low temperatures, abrasion and abrasion resistance, low coefficient of friction and good chemical resistance. to provide. These properties make polyamides among the strongest of all available man-made fibers.

The dyeing efficiency of polyamide fibers is related to the carboxyl end group -COOH, and in particular the amine end group -NH ₂ , which exhibits polar and hydrophilic characteristics. Dye diffusion into the fibers is related to amorphous and crystalline balance, molecular orientation, molecular weight, intramolecular and intermolecular bonds and available hydroxyl or polar groups.

Dye color absorption, dyeing rate, homogeneity and fastness depend on dyeing process conditions such as temperature, time and pH, and also on dyeing equipment such as discharge or padding equipment. Chemical adjuvants, such as leveling agents, surfactants, retardants, fixing agents, etc., are also important for effective dyeing.

Dyes are classified according to their chemical composition, reaction mechanism, molecular size, and the like. The most common types of dyes are reactive dyes, direct dyes, basic dyes, acid dyes, metallic dyes, azo dyes, disperse dyes and vat dyes. Polyamides contain primary amino end-groups which are more suitable for acid dyes, for which best dye absorption and fastness are obtained. Acid dyes contain hydrophilic groups of sodium sulfonate radicals (-SO ₃ Na) which can be combined with amino groups (-NH ⁺ ) of polyamide fibers by ionic bonding or electrostatic forces to give better dyeability and brighter colors do. The remainder of the aforementioned dyes are combined with the polyamide fibers by hydrogen bonding or van der Waals forces to provide a brighter color. For example, when polyamides are dyed with disperse dyes, color build-up is not affected by chemical fluctuations of the fibers, thus obtaining a more uniform color. However, the use of disperse dyes for polyamides is limited to pale shades due to poor color accumulation and fastness properties, as disperse dyes are insoluble dyes that diffuse into fibers rather than combine by chemical interactions.

Typical temperatures and process times for polyamide dyeing are boiling temperatures (about 100° C.) and processing times of 60 minutes. This temperature is known to be essential to create a swelling morphology structure of the fiber by separating the molecules and breaking the intermolecular bonds, allowing the dye to diffuse into the interior of the fiber and form permanent chemical bonds. A time of 60 minutes is known to be required to achieve a deep, even and homogeneous color. However, these temperatures and times are energy consuming and not environmentally friendly.

Several attempts have been made to optimize the dyeing process to reduce time, temperature, energy, chemical aids and water to improve efficiency, productivity and reduce carbon footprint. Additionally, there have been plans to modify the chemical composition of the dyes to make them more sustainable and efficient for optimized dyeing conditions. Experiments were also conducted to increase the affinity of aliphatic polyamides for anionic dyes by increasing the amino end group content. These approaches provide deeper and darker colors, but are not aimed at reducing the dyeing temperature and time.

In light of this, so far, no solution exists for improving the dyeing properties of polyamides, such as the inherent low temperature and faster dyeing properties.

The present invention therefore aims to find a solution for obtaining polyamide articles which are dyed at significantly lower temperatures and times and which give a dark, homogeneous and durable color; Surprisingly, the present inventors have found that certain polyamide fiber blends have improved dyeing performance, such as low temperature dyeing of dark and light colors and reduced dyeing time.

Accordingly, the present invention relates to at least two different polyamides:

- polyamide 6, polyamide 6.6, polyamide 6.9, polyamide 6.12, polyamide 6.10, polyamide 11, polyamide 12, polyamide 10.10, polyamide 4.6, polyamide 4.10, polyamide 12.12, polyamide 10.12 and these a first polyamide which is an aliphatic polyamide selected from the group consisting of a mixture of

- a second polyamide selected from polyamide 5.X, wherein X is an integer from 4 to 16 and mixtures thereof

polyamide fibers having improved dyeing properties.

Surprisingly, the intrinsic morphological properties of polyamides, mainly intermolecular amide bonds, are altered, making polyamide fibers more susceptible to swelling and chemical interactions at lower temperatures. Thus, uniform, dark, durable colors can be achieved in a more efficient and environmentally friendly process.

The present invention also relates to obtaining polyamide fibers with improved dyeing properties, wherein the polyamide fibers are obtained by melt-spinning extrusion of at least a first and a second polyamide as defined in the specification above and below. aim the way

The present invention also relates to a polyamide article comprising polyamide fibers having improved dyeing properties as defined in the preceding and following paragraphs; and modifying the polyamide fibers of the present invention by texturing, drawing, warping, knitting, weaving, non-woven processing, garment making, or combinations thereof. A method for obtaining such polyamide articles is proposed.

Next, another object of the present invention is to improve the dyeing properties of the polyamide fibers produced, polyamide 6, polyamide 6.6, polyamide 6.9, polyamide 6.12, polyamide 6.10, polyamide 11, polyamide Polyamide 5.X in combination with at least a first polyamide which is an aliphatic polyamide selected from the group consisting of 12, polyamide 10.10, polyamide 4.6, polyamide 4.10, polyamide 12.12, polyamide 10.12 and mixtures thereof, wherein , X is an integer from 4 to 16) or mixtures thereof.

Justice

The expression "polyamide fiber" within the meaning of the present invention is a general term encompassing the following spun articles: fibers, monofilaments, multifilaments and yarns.

A "polyamide article" according to the invention is a modified or treated polyamide fiber, which comprises staple fibers made of polyamide fibers, any flock or any textile composition, in particular fabrics and/or garments. include In the following description, the terms "fiber", "yarn" and "filament" may be used equivalently without changing the meaning of the present invention.

Polyamide fibers with improved dyeing properties

The present invention provides polyamide fibers with improved dyeability, such as faster low temperature dyeing of dark and light colors. The polyamide fibers with improved dyeing properties according to the invention are blends of at least two different polyamides, namely a first polyamide and a second polyamide.

first polyamide

The first polyamide is polyamide 6, polyamide 6.6, polyamide 6.9, polyamide 6.12, polyamide 6.10, polyamide 11, polyamide 12, polyamide 10.10, polyamide 4.6, polyamide 4.10, polyamide 12.12, aliphatic polyamides of type AB and/or AABB, selected from the group consisting of polyamide 10.12 and mixtures thereof.

It is preferably polyamide 6 or polyamide 6.6 and mixtures thereof; Even more preferably it is selected from the group consisting of poly(hexamethylene adipamide) (polyamide 6.6 or nylon 6.6).

Such polyamides are well known in the art and can be obtained by polycondensation of commercially available mixtures of diacid and diamine monomers or salts thereof. Diamines and diacids of the polyamide AABB type are tetramethylenediamine (1,4-diaminobutane or putrescine), hexamethylenediamine (1,6-hexanediamine), dodecamethylenediamine (1,12-diamino It belongs to the group of decane), hexanedioic acid (adipic acid), nonanedioic acid (azelaic acid), decanedioic acid (sebacic acid), undecanedioic acid, and dodecanedioic acid. Monomers of the polyamide AB type belong to the group of caprolactam, 11-aminoundecanoamide, dodecanolactam or laurolactam.

In the case of poly(hexamethylene adipamide) (polyamide 6.6), the main monomers are hexamethylenediamine and adipic acid. However, these monomers may contain up to 25 mol % of other diamines or diacid monomers or even amino acid or lactam monomers.

In particular, the amino acid is aminocaproic acid and the lactam is caprolactam.

Preferred first polyamides may have a viscosity index (IVN) in the range from 100 ml/g to 200 ml/g, preferably from about 120 ml/g to 170 ml/g. This IVN is determined according to the standard ISO 307 described in the experimental part below.

The amino end groups (ATG) content of these polyamides is advantageously from 25 equivalents/ton to 60 equivalents/ton, and the carboxyl end groups (CTG) advantageously from 45 equivalents/ton to 90 equivalents/ton. These amino/carboxyl end group content are determined according to the method described in the experimental section below.

The opacity of this first polyamide may be brilliant, semi-dull, full-dull, and mixtures thereof. Opacity is related to the amount of titanium dioxide present in the polymer, which is related to dyeability, gloss and processability issues. For example, Brilliant has a lower amount of titanium dioxide, while full-less has a higher amount of titanium dioxide.

A particularly preferred first polyamide according to the invention is polyamide 6.6 containing 1% to 5% caprolactam. This polyamide advantageously has an IVN (viscosity index) of 128 to 132 and ATG (amine end groups) of 40 to 45, which is a full-less polymer.

secondary polyamide

The second polyamide is polyamide 5.X, wherein X is an integer from 4 to 16, and mixtures thereof. More preferably, the second polyamide is an odd/even polyamide, such as polyamides 5.4, 5.6, 5.8, 5.10, 5.12, 5.14. In a preferred embodiment, the second polyamide of the polyamide fibers according to the invention is polyamide 5.6 or polyamide 5.10. The best results with regard to the dyeing properties are obtained when the second polyamide is polyamide 5.6.

Polyamide 5.X is prepared from pentamethylenediamine and aliphatic dicarboxylic acid(s) as raw materials.

The list of possible dicarboxylic acids is as follows: butanedioic acid (succinic acid), pentanedioic acid (glutaric acid), hexanedioic acid (adipic acid), heptanedioic acid (pimelic acid), octanedioic acid (suberic acid) ), nonanedioic acid (azelaic acid), decanedioic acid (sebacic acid), undecanedioic acid, dodecanedioic acid, brassylic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid.

All of these diacids are commercially available.

Polyamides 5.6 and 5.10 have the advantage that they can be prepared from biomass according to ASTM6866. As pentamethylenediamine can also be prepared from biomass according to ASTM6866, the resulting polyamide is at least 45% bio-sourced and can be up to 100% derived from biomass.

Polyamide 5.6 is also known as poly(pentamethylene adipamide), which consists of pentamethylenediamine and adipic acid as raw materials.

Preferred polyamide 5.6 may have a viscosity index (IVN) in the range from 100 ml/g to 200 ml/g, preferably from about 120 ml/g to 170 ml/g. This IVN is determined according to the standard ISO 307 described in the experimental part below.

The amino end group (ATG) content is advantageously from 25 equivalents/ton to 60 equivalents/ton, and the carboxyl end group (CTG) content is preferably from 45 equivalents/ton to 90 equivalents/ton.

These amino/carboxyl end group content are determined according to the method described in the experimental section below.

The opacity of this second polyamide can be brilliant, semi-less, full-less and mixtures thereof, as described above for the first polyamide.

Particularly preferred polyamide 5.6 according to the invention has an IVN (viscosity index) of 138 to 142 and ATG (amine end groups) of 38 to 42, which is a brilliant polymer, ie the polyamide does not contain titanium dioxide.

The polyamide fibers according to the invention are particularly advantageous when the second polyamide is present in an amount of from about 1.0% to 40.0% by weight, preferably from about 5.0% to 20.0% by weight of the total weight of the polyamide fibers. Do. Best practice is when the second polyamide, in particular polyamide 5.6, is present in an amount of from 5% to 10% by weight of the total weight of the polyamide fibers.

Polyamide fibers according to the invention advantageously have a total dtex of about 40 to 300 and a dpf (dtex per filament) of about 1 to 5. The stiffness (elongation at break) is 30 cN/dtex to 80 cN/dtex. The elongation at break is between 20% and 90%.

Indeed, the combination of the above preferred technical characteristics of the first and second polyamides, in combination with sufficient and satisfactory mechanical properties of the fibers for textile articles, makes it possible to obtain even better dyeing behaviors.

Method for obtaining polyamide fibers with improved dyeing properties

The present invention also provides a process for obtaining polyamide fibers as described above. The method includes forming a polyamide fiber blend by melt-spinning extrusion using at least the first and second polyamides described above.

According to the invention, the expression "melt-spinning" is understood to mean an extrusion process in which polyamide in melt form is converted into polyamide fibers. The polyamide(s) may be fed into the melt-spinning apparatus in the form of pellets, powder or melt. The process includes any conventional extrusion spinning means suitable for melt-spinning extrusion of polyamides, these means well known to those skilled in the art, such as single-screw extruders, double-screw extruders, two-component extruders and grid spinning. is the head Melt-spun extrusion can additionally be LOY (low oriented yarn), POY (partially oriented yarn), FDY (fully drawn yarn), FOY (fully oriented yarn), LDI (low denier industrial) or HDI (high denier industrial) is defined as being

first embodiment

According to a first embodiment, melt spinning extrusion comprises:

a1. feeding a first polyamide as a melt, pellet or powder into an inlet of a screw extruder or grid spinning head;

a2. melting, homogenizing and pressing the polyamide;

a3. spinning the molten polyamide into fibers;

a4. cooling and winding the fibers

wherein the second polyamide is introduced continuously as pellets or powder during step a1, preferably using an injection device.

As mentioned above, the second polyamide is preferably introduced continuously during step a1 of the single-screw extruder. It can be added as polyamide pellets or powder by means of an injection device, such as an infusion pump or a gravimetric feeding device, preferably a gravimetric feeding device. According to this embodiment, prior to formation of the fibers, the second polyamide is melt-mixed with the first polyamide. The second polyamide may optionally be dried prior to introduction in step a1.

In a specific embodiment of the present invention, the second polyamide is introduced continuously as pellets by a gravimetric feeding device, and the amount added is 5% by weight of the total weight of the polyamide fibers.

Best results are obtained in a preferred embodiment wherein the second polyamide is introduced continuously as pellets by means of a gravimetric feeding device and the amount added is 10% by weight of the total weight of the polyamide fibers.

second embodiment

According to a second embodiment, melt-spinning extrusion comprises:

a'1. feeding a blend of at least a first and a second polyamide as melt, pellets or powder into an inlet of a screw extruder or grid spinning head;

a2. melting, homogenizing and pressing the polyamide;

a3. spinning the molten polyamide into fibers;

a4. cooling and winding the fibers

wherein the blend of at least first and second polyamides precedes step a′1 comprising polymerization of diacid and diamine monomers corresponding to at least the first and second polyamides or salts thereof. obtained by a0.

The polymerization of step a0 generally comprises the following steps: 1- Concentrating by evaporation of water a nylon salt which is a combination of diacid and diamine monomers corresponding to at least the first and second polyamides or salts thereof; 2- polymerizing the concentrated nylon salt under pressure; 3- Reducing the pressure of the polymerization medium to remove residual water by evaporation; 4- optionally, maintaining the polymer temperature at ambient pressure or under reduced pressure to obtain a desired degree of polymerization; 5- Recovering the polyamide as a melt or transforming the molten polyamide into pellets.

third embodiment

According to a third embodiment, melt-spinning extrusion comprises:

a1. feeding a first polyamide as a melt, pellet or powder into an inlet of a screw extruder or grid spinning head;

a2. melting, homogenizing and pressing the polyamide;

a3. spinning the molten polyamide into fibers;

a4. cooling and winding the fibers

wherein the second polyamide is introduced continuously as polyamide melt, preferably during step a3 of a screw extruder, preferably of a single-screw extruder. It is added by means of a further screw extruder, preferably a single-screw extruder. According to this embodiment, the second polyamide, upon fiber formation, is blended with the first polyamide as it exits the spin pack spinneret, thereby forming a two-component fiber.

all implementations

In the process according to the invention, according to any of the first or second or third embodiments described above, the second polyamide is advantageously added in an amount of from 1.0% to 40.0% by weight, preferably from 1.0% to 40.0% by weight of the total weight of the polyamide fibers. Preferably, it is introduced in an amount of 5.0% by weight to 20.0% by weight.

In steps a2 and a3, the term "polyamide" also means "polyamide blend" when at least both the first and second polyamides are present.

In step a2, the polyamide (or polyamide blend) is fed in a screw extruder, preferably at a temperature above the melting temperature of the first and second polyamides of 280° C. to 310° C. and from 30 bar to 70 bar. Melt, homogenize and pressurize at extrusion pressure.

Then, according to step a3, the molten polyamide (or polyamide blend) is prepared, preferably at a temperature of 260°C to 310°C, at a spin pack pressure of 150 to 250, and from 3 kg/h to 8 kg/h At a spin pack flow rate of

Step a4 is a step in which the fibers (or yarns or filaments) are cooled to a solidified form, and the polyamide fibers are wound into bobbins. This step may also add spinning oil onto the fibers.

In the present invention, the extruder will be equipped with a metering system and/or further single-screw extruder for introducing, in steps a1 and/or a3 and/or a4, the polymer and optionally additives, such as a masterbatch, into the main polymer. can

Additives may be introduced during the process of the invention or may be present in the first and second polyamide pellets. Additives may include antioxidants, stabilizers such as heat or light stabilizers, colorants, pigments, nucleating agents such as talc, matifying agents such as titanium dioxide or zinc sulfide, processing aids, biocides, viscosity modifiers, catalysts, far infrared emitting minerals, biodegradable "conversion" additives, antistatic additives, functional additives, optical brighteners, nanocapsules, antibacterial agents, antimite agents, antifungal agents or other conventional additives. These additives are generally added into the polymer or in steps a1 and/or a4 of melt-spinning extrusion, in an amount of from 0.001% to 10% by weight of the polyamide article.

The resulting polyamide fibers obtained according to the first, second and third embodiments described above can be dyed.

Improved dyeing properties are generally obtained using dyes consisting of reactive dyes, direct dyes, acid dyes and metallic dyes, preferably reactive dyes or acid dyes.

These dyes are combined with polyamide fibers by a chemical reaction and thus will have the advantage of faster and lower temperature dyeing, where the molecular structures can form chemical bonds. In a preferred embodiment of the invention, acid dyes are advantageously used due to their high compatibility with polyamide amine end-groups.

When dyeing the polyamide fibers obtained according to the first, second or third embodiment described above, the dyeing is carried out at a temperature of 40°C to 80°C, preferably 60°C ± 5°C.

when dyeing the polyamide fibers obtained according to the first, second or third embodiment described above; The staining is preferably carried out with a staining cycle of 20 to 40 minutes, preferably 30 minutes ± 5 minutes.

polyamide articles

The polyamide fibers according to the invention can then be transformed into polyamide articles, in particular textile fabrics and/or garments.

The polyamide article according to the invention is preferably a fiber, staple fiber, flock, woven, knitted or non-woven fabric or fabric made from a polyamide fiber of the invention (as defined above) or obtained from a process according to the invention. is a commodity

The textile article may be any textile article known in the art, including, but not limited to, woven fabrics, knitted fabrics, non-woven fabrics, ropes, cords, sewing threads, and the like.

The polyamide article is preferably dyed, in particular with acid dyes.

Improved dyeing properties are generally obtained using dyes consisting of reactive dyes, direct dyes, acid dyes and metallic dyes. These dyes are combined with polyamide fibers by a chemical reaction and thus will have the advantage of faster and lower temperature dyeing, where the molecular structures can form chemical bonds. Most preferably reactive dyes and acid dyes. In a preferred embodiment of the invention, acid dyes are advantageously used due to their high compatibility with polyamide amine end-groups.

How to obtain a polyamide article

Methods for transforming polyamide fibers into polyamide articles, such as textile fabrics or garments, are well known to those skilled in the art. Indeed, polyamide fibers can be transformed into polyamide articles by texturing, drawing, warping, knitting, weaving, non-woven processing, garment making, or combinations thereof.

The method of obtaining the polyamide article may further comprise a dyeing step.

Improved dyeing properties are generally obtained using dyes consisting of reactive dyes, direct dyes, acid dyes and metallic dyes. These dyes are combined with the polyamide fibers by a chemical reaction and thus will have the advantage of faster and lower temperature dyeing, where the molecular structures can form chemical bonds. Most preferably, reactive dyes and acid dyes are selected for the dyeing step. In a preferred embodiment of the invention, acid dyes are advantageously used due to their high compatibility with polyamide amine end-groups.

When dyeing the polyamide articles obtained according to the invention, the dyeing is carried out at a temperature of 40°C to 80°C, preferably 60°C ± 5°C.

When dyeing the polyamide article obtained according to the invention, the dyeing is preferably carried out with a dyeing cycle of 20 minutes to 40 minutes, preferably 30 minutes ± 5 minutes.

These articles are then used in many articles, particularly carpets, rugs, upholstery, parachutes, tents, bags, socks, underwear, sportswear, outerwear, and the like.

An advantage of the polyamide fibers according to the invention and articles made therefrom is that they have improved dyeability, such as low-temperature dyeing of dark and light colors and reduced dyeing times. Thus, with a more efficient and environmentally friendly process, the dyeing can be achieved with a uniform, dark, durable color.

Other details or advantages of the present invention will become more apparent by reference to the examples provided below.

Example

A series of polyamide articles (Examples 1 to 12), including comparative polyamide articles (Examples 1 to 9 and 12), were formed, including wash fastness, alkali and acid perspiration fastness, CIE Lab color strength "L", It is evaluated for IVN (viscosity index) and ATG (terminal amino groups).

Amino end group (ATG) content

Amino end group (ATG) content was determined by potentiometric titration method. An amount of 2 grams of polyamide is added to about 70 ml of 90% wt of phenol. The mixture is maintained at a temperature of 40° C. under stirring until complete dissolution of the polyamide. The solution is then titrated with 0.1 N HCl at about 25°C. Results are reported as equivalents/ton (eq/ton). When analyzing fibers and articles, any residue or spin-finish must be removed beforehand.

Solution Viscosity (IVN)

The determination of solution viscosity (IVN) is carried out according to ISO 307. The polyamide is dissolved in 90% wt formic acid at 25° C. at a concentration of 0.005 g/ml, and its flow time is measured. Results are reported as ml/g.

Washing fastness ISO 105 - C06

Samples are washed with conventional detergent (4 g/l) at 40° C. for 30 minutes. It is then rinsed 3 times in separate portions of 100 ml of water. Samples are evaluated according to the gray scale for color change (ISO 105 - A02) and the coloration of adjacent fabrics (ISO 105 - A03). The rating varies from 0 to 5, where 0 is “low” and 5 is “high”.

Fastness to perspiration ISO 105 - E04

Acid and alkali perspiration were evaluated. Samples were placed in contact with a standard adjacent fabric (for color transfer), immersed in simulated alkali and acid solutions (pH 8.0 and 5.5, respectively), drained, and at a specific pressure in a testing apparatus (perspiometer), Place between the two plates under temperature and time (37±2° C., 4 hours, 5 kg pressure). The color change of the sample and the coloration of the adjacent fabric are evaluated by the gray scale for color change (ISO 105 - A02) and coloration (ISO 105 - A03). The rating varies from 0 to 5, where 0 is “low” and 5 is “high”.

Color Intensity - CIE 15:2004

The polyamide article color intensity "L" was determined by the standardized method CIE L ^* a ^* b ^* (Standard CIE 15:2004 of "Commission internationale de l'eclairage"). In this method, polyamide articles are evaluated using a spectrophotometer or colorimeter, and L ^* a ^* and b ^* coordinates are obtained from the instrument. The luminance coordinate "L" varies from 0 to 100, where 0 is "black" and 100 is "white". The measurement uses a light source type D65, and an observation angle of 10°. The lower this parameter, the darker the color.

1. Study the effect of staining temperature and cycle time

Comparative Examples 1 to 4 - 100% polyamide 5.6 BR

Synthesis and source of polyamide of polyamide 5.6 BR

Polyamide 5.6 pellets are polyamides commercially available from Cathay Biotech under the trade name Terryl ^® . It is a brilliant polyamide containing no titanium dioxide. The IVN (viscosity index) is 138 to 142, and the ATG (amine end groups) is 38 to 42 (measured according to the methods disclosed herein).

Synthesis of fibers and articles based on polyamide 5.6 BR

Polyamide fibers were obtained during melt-spinning extrusion of the polyamide 5.6 BR (Brilliant).

The obtained multifilament polyamide fibers were further textured to a linear density of 2x80f68 dtex and knitted into a fabric. The obtained stiffness was 30.0 cN/tex, and the elongation was 28.6%. The knitted fabric was dyed in the ejection equipment as follows:

Comparative Example 1 - 100°C - 60 minutes

Comparative Example 2 - 70 °C - 30 minutes

Comparative Example 3 - 60°C - 30 minutes

Comparative Example 4 - 50°C - 30 minutes

The amount used was 3.5%wt for the black acid dye and 1%wt for the leveling agent. The pH of the solution was adjusted to 3-4 with ammonium sulfate and acetic acid. The bath relationship was 1:30, meaning 1 part fabric per 30 parts water.

Comparative Examples 5 to 8 - 100% polyamide 6.6 BR

Synthesis and source of polyamide 6.6 BR

Polyamide 6.6 pellets were made by Rhodia Poliamida e Especialidades Ltda. It is a brilliant polyamide (without titanium dioxide) prepared primarily from the polymerization of a nylon salt containing hexamethylenediamine and adipic acid. IVN (viscosity index) is 128 to 132, and ATG (amine end groups) is 40 to 45 (measured according to the methods disclosed herein).

Synthesis of fibers and articles based on polyamide 6.6 BR

Polyamide fibers were obtained during melt-spinning extrusion of the polyamide 6.6 BR (Brilliant).

The obtained multifilament polyamide fibers were further textured to a linear density of 2x80f68 dtex and knitted into a fabric. The obtained stiffness was 31.5 cN/tex, and the elongation was 28.8%.

The knitted fabric was dyed in the ejection equipment as follows:

Comparative Example 5 - 100°C - 60 minutes

Comparative Example 6 - 70 °C - 30 minutes

Comparative Example 7 - 60 ℃ - 30 minutes

Comparative Example 8 - 50°C - 30 minutes

The amount used was 3.5%wt for the black acid dye and 1%wt for the leveling agent. The pH of the solution was adjusted to 3-4 with ammonium sulfate and acetic acid. The bath relationship was 1:30, which means 1 part fabric per 30 parts water.

evaluation

Each of the comparative examples (1 to 8) was evaluated for washing fastness, alkali and acid perspiration fastness, CIE Lab color intensity “L”, IVN (viscosity index) and ATG (amino end groups). The results are shown in Table 1 below.

^* Rating for color transfer to adjacent fabrics. The color change (not shown) of the samples was rated as grade 5 (maximum) in all of the above examples.

conclusion

From Comparative Examples 1 to 4 (polyamide 5.6), the black color intensity starts to decrease at a temperature of 60° C. or lower, meaning that this is the minimum temperature for dyeing a dark color such as black used in the experiment. On the other hand, in Comparative Examples 5 to 8 (polyamide 6.6), a sharp decrease in color intensity was already obtained at 70°C. Comparing Examples 4 and 6 (where they achieve the same strength (Example 4 = 15.1 and Example 6 = 15.2)), it can be concluded that there is a 20 °C difference in the dyeing behavior between polyamide 5.6 and polyamide 6.6 there is. Therefore, 60° C. is the optimum temperature for dyeing polyamide 5.6 with a dark tint.

Examples 1 to 8 cannot be directly compared with Examples 9 to 12 below due to the difference in opacity. Full-less polymers contain a higher amount of titanium dioxide and, therefore, exhibit a brighter hue than brilliant polymers with the same amount of dye. Examples 1 to 8 are comparable within themselves and are important in setting the optimum dyeing temperature and time for the present invention. On the other hand, Examples 9 to 12 are comparable within themselves and show the advantages obtained by the present invention with respect to color absorption and fastness.

2. Test with reduced staining temperature and cycle time

Inventive Examples 10 and 11 - Polyamide Blends

A polyamide fiber blend was obtained during melt-spun extrusion. The first polyamide was polyamide 6.6 FD (full-less). This polyamide was prepared analogously to Comparative Examples 5 to 8, which was full-less (containing about 1.5% titanium dioxide).

The second polyamide was polyamide 5.6 (Brilliant) as described above for Comparative Examples 1-4.

The second polyamide was introduced continuously during step a1 of the single-screw extruder as polyamide pellets by means of a gravimetric feed device. In step a2, the polyamide blend was melted, homogenized and pressed inside a screw extruder at a temperature of about 290° C. and an extrusion pressure of about 50 bar. Then, according to step a3, the molten polyamide blend was spun into a multifilament yarn at a spin pack pressure of about 200 bar and a spin pack flow rate of about 5 kg/h. In step a4, the polyamide fiber blend was solidified and wound onto a bobbin at 4200 m/min.

In Example 10, polyamide 5.6 was added continuously in step a1 at 5% weight of the total polyamide blend.

In Example 11, polyamide 5.6 was added continuously in step a1 at 10% by weight of the total polyamide blend.

The resulting multifilament polyamide blend was further textured to a linear density of 2x80f68 dtex and knitted into a fabric. The knitted fabric was dyed in a discharge equipment at a temperature of 60° C. for 30 minutes. The amount used was 3.5%wt for the black acid dye and 1%wt for the leveling agent. The pH of the solution was adjusted to 3-4 with ammonium sulfate and acetic acid. The bath relationship was 1:30, which means 1 part fabric per 30 parts water.

Comparative Example 9 - 100% Polyamide 6.6 FD

Polyamide fibers were obtained during melt-spinning extrusion. The polyamide was polyamide 6.6 FD (full-less) described/prepared above for Examples 10 and 11.

The obtained multifilament polyamide fibers were further textured to a linear density of 2x80f68 dtex and knitted into a fabric. The knitted fabric was dyed in a discharge equipment at a temperature of 60° C. for 30 minutes. The amount used was 3.5%wt for the black acid dye and 1%wt for the leveling agent. The pH of the solution was adjusted to 3-4 with ammonium sulfate and acetic acid. The bath relationship was 1:30, which means 1 part fabric per 30 parts water.

Comparative Example 12 - 100% Polyamide 6 FD

The polyamide was polyamide 6, FD (full-less). This textured polyamide yarn was obtained as a bobbin from Antex Ltda.

Multifilament polyamide fibers were knitted into the fabric. The knitted fabric was dyed in a discharge equipment at a temperature of 60° C. for 30 minutes. The amount used was 3.5%wt for the black acid dye and 1%wt for the leveling agent. The pH of the solution was adjusted to 3-4 with ammonium sulfate and acetic acid. The bath relationship was 1:30, which means 1 part fabric per 30 parts water.

In all of the above examples, a subsequent fixing step was performed using 3% wt of a fixing agent at 80° C. for 30 minutes.

evaluation:

Each of the examples (Examples 9-12) was evaluated for wash fastness, alkali and acid perspiration fastness, CIE Lab color intensity “L”, IVN (viscosity index) and ATG (terminal amino groups). The results are shown in Table 2 below.

^* Rating for color transfer to adjacent fabrics. The color change (not shown) of the samples was rated as grade 5 (maximum) in all of the above examples.

conclusion

For the inventive blends (Examples 10 and 11), the polyamide articles were also effectively dyed at 60° C. for dark colors (eg black). According to the results, Examples 10 and 11 add 5% and 10% polyamide 5.6 respectively during melt-spinning extrusion of polyamide 6.6, in half the time of a typical dyeing cycle (30 minutes instead of 60 minutes) By doing so, a stronger black (L=24.6 and L=19.5, respectively) was achieved compared to Comparative Example 9 (L=30.6).

This represents a significant reduction compared to the conventional boiling temperature and demonstrates that the same dyeing advantages exhibited by polyamide 5.6 can also be obtained using a blend of polyamide 5.6 and polyamide 6.6.

In summary, low temperature dyeing properties and shorter dyeing cycles are possible with the polyamide 5.6 and polyamide 6.6 fiber blends. The resulting color fastness of the polyamide blended articles (Examples 10 and 11) is also superior to the polyamide 5.6 article alone (Examples 1 and 3). In addition, the dyeing properties of the polyamide fiber blend are superior to that of the conventional polyamide 6 (Example 12).

Claims (19)

at least two different polyamides, i.e.
- a first polyamide which is an aliphatic polyamide selected from the group consisting of polyamide 6 and polyamide 6.6 and mixtures thereof, and
- a second polyamide that is polyamide 5.6
is a blend of polyamide fibers with improved dyeing properties,
wherein the second polyamide is present in an amount of from 10% to 40.0% by weight of the total weight of the polyamide fiber. A method for obtaining polyamide fibers with improved dyeing properties, as defined in claim 1 , wherein the polyamide fibers are obtained by melt-spinning extrusion of at least the first and second polyamides as defined in claim 1 . The method of claim 2, wherein the melt-spinning extrusion comprises:
a1. feeding a first polyamide as a melt, pellet or powder into an inlet of a screw extruder or grid spinning head;
a2. melting, homogenizing and pressing the polyamide;
a3. spinning the molten polyamide into fibers;
a4. cooling and winding the fibers
wherein the second polyamide is introduced continuously during step a1 in the form of pellets or powder. 4. The method according to claim 3, wherein the second polyamide is introduced continuously using an injection device. The method of claim 2, wherein the melt-spinning extrusion comprises:
a'1. feeding a blend of at least a first and a second polyamide as melt, pellets or powder into an inlet of a screw extruder or grid spinning head;
a2. melting, homogenizing and pressing the polyamide;
a3. spinning the molten polyamide into fibers;
a4. cooling and winding the fibers
wherein the blend of at least first and second polyamides precedes step a′1 comprising polymerization of diacid and diamine monomers corresponding to at least the first and second polyamides or salts thereof. a0. The method of claim 2, wherein the melt-spinning extrusion comprises:
a1. feeding a first polyamide as a melt, pellet or powder into an inlet of a screw extruder or grid spinning head;
a2. melting, homogenizing and pressing the polyamide;
a3. spinning the molten polyamide into fibers;
a4. cooling and winding the fibers
wherein the second polyamide is introduced continuously as polyamide melt during step a3. Process according to claim 6, wherein the second polyamide is introduced continuously during step a3 by means of a further single-screw extruder. 7. The method according to any one of claims 2 to 6, wherein the second polyamide is present in an amount of 10% to 40.0% by weight of the total weight of the polyamide fibers. 7. A method according to any one of claims 2 to 6, wherein the resulting polyamide fibers are dyed. 10. The method of claim 9, wherein the polyamide fiber is dyed at a temperature of 40°C to 80°C, or 60°C ± 5°C. 10. The method of claim 9, wherein the polyamide fibers are dyed with a dyeing cycle of 20 to 40 minutes, or 30 minutes ± 5 minutes. A polyamide article comprising polyamide fibers having improved dyeing properties, as defined in claim 1 or obtained from a method as defined in claim 2 . 13. The polyamide article of claim 12, wherein the polyamide article is a fiber, staple fiber, flock, woven, knitted or non-woven fabric or textile article. 13. A method for obtaining a polyamide article as defined in claim 12, wherein the polyamide fibers as defined in claim 12 are modified by texturing, drawing, warping, knitting, weaving, non-woven processing, garment making or combinations thereof. 15. The method according to claim 14, wherein the polyamide article is dyed. 15. The method of claim 14, wherein the polyamide article is dyed at a temperature of 40°C to 80°C, or 60°C ± 5°C. 15. The method of claim 14, wherein the polyamide article is dyed with a dyeing cycle of 20 to 40 minutes, or 30 minutes ± 5 minutes. Dyeing properties of polyamide fibers prepared therefrom, at least in combination with a first polyamide which is an aliphatic polyamide selected from the group consisting of polyamide 6 and polyamide 6.6 and mixtures thereof, a second polyamide which is polyamide 5.6 wherein the second polyamide is present in an amount of 10% to 40.0% by weight of the total weight of the polyamide fiber. delete