Classifications

• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06P—DYEING OR PRINTING TEXTILES; DYEING LEATHER, FURS OR SOLID MACROMOLECULAR SUBSTANCES IN ANY FORM
  • D06P3/00—Special processes of dyeing or printing textiles, or dyeing leather, furs, or solid macromolecular substances in any form, classified according to the material treated
  • D06P3/58—Material containing hydroxyl groups
  • D06P3/60—Natural or regenerated cellulose
  • D06P3/66—Natural or regenerated cellulose using reactive dyes

Definitions

• the present invention relates to a method for permanently dyeing cellulose-based textiles.
• Said methods differ from one another depending on the type of fiber (natural, artificial or synthetic fiber) and on the form thereof (fiber, yarn, fabric or garment).
• every dyeing method uses given classes of dyes, operating conditions and dyeing devices.
• Reactive dyes are particularly preferred for dyeing cellulose piece-shaped fabrics.
• Reactive dyes are known to be substances that bind to textile cellulose fibers by forming covalent bonds with said fibers.
• a reactive dye comprises: at least one chromophore group (giving color), at least one reactive group (or leaving group) and a bridge group placed between said chromophore group and said leaving group.
• reactive dyes are divided into monofunctional and bifunctional groups.
• reactive leaving groups the following can be mentioned by way of example: halides (Cl, Br), sulfonamides, phthalazines, pyrimidines.
• chromophore groups the following can be mentioned by way of example: groups with a system of conjugated double bonds such as azoic groups, azomethinic groups, quinone groups, ethylene groups.
• bridge groups the following can be mentioned by way of example: alkylene radicals of variable length (methylene, ethylene and higher radicals), interrupted if necessary by nitrogen atoms (secondary or tertiary atoms), oxygen, sulfur, or by groups such as amido groups, carbamyl groups, carbamoyl groups, ureic groups and the like.
• reactive dyes are further divided into: dyes to be applied at low temperature (30-40°C), at medium temperature (50-60°C) and at high temperature (80-90°C).
• US 3,616,069 discloses a process for colouring cellulose textile materials by impregnating the material with a water-soluble dye containing a cellulose-reactive group and fixing the dye on the material by treatment with an alkali applied in the dyebath or a separate bath in an amount sufficient to fix cellulose-reactive dyes. Impregnation with the dyestuff is carried out in neutral or slightly acid solution at up to 130°C, provided that the temperature is lowered to its normal value before adding the alkali.
• US 5,936,072 discloses improved reactive dyes endowed with excellent fixation yields and superior fibre-dye bond stability.
• the above reactive dyes may be used for dyeing according to an exhaust process, which is usually carried out in aqueous medium at a temperature in the range from 20 to 105°C, in particular from 30 to 90°C and preferably, from 40 to 80°C.
• Another suitable method is a pad-dyeing process, wherein the goods are usually impregnated with aqueous and, when required, saline, dye solutions.
• JP 11 323744 A discloses a method for exhaustion dyeing of a cellulosic fibrous material carried out in a bath at a pH within the range of 3-6 and at a temperature within the range of 70-100°C. Then the reactive dye is fixed on the cellulosic fibrous material in the presence of an alkaline agent at a temperature within 30°-90°C.
• EP 0 637 615 A2 discloses red reactive dyes of specific formula (I) which can be used for dyeing various materials, particularly cellulose fibers and which are excellent in various fastness properties.
• the cellulose fibers may be subject to exhaustion dyeing, in which an acid-binding agent is used and dyeing is conducted by an addition of a neutral salt such as Glauber's salt or sodium chloride, usually at 50°-60°C.
• Color solidity commonly refers to the resistance of the color of a textile to degradation, i.e. to loss of color due to various factors such as for instance light, humidity, heat, washing.
• color degradation due to textile washing is determined by comparing the color of the unwashed textile with the color of the same textile after washing (or after a series of repeated washing operations), referring to the gray scale for color variation as provided by international norm ISO 105 A02 (and by corresponding Italian norm UNI EN 20105 A02/'96).
• Said gray scale is made up of 10 pairs of gray plates, a plate of each pair being characterized by a decreasing gray intensity.
• intensity and contrast difference varies: to every intensity difference correspond different values of color degradation, which are classified according to a scale going from 5 to 1 (also comprising intermediate values).
• Degree 5 corresponds to two identical gray plates, i.e. with no color difference; said degree means therefore an inexistent degradation to washing (or to the number of washing operations that have been carried out).
• Degree 1 corresponds to the maximum degree of color contrast between the two gray plates; said degree means therefore a very high degradation to washing, i.e. the maximum degradation as possible.
• said washed sample is compared with the unwashed original sample and the color contrast between said two samples is compared with the contrast of gray tones between the pairs of plates of the gray scale.
• black, blue, brown and green are known to be the most delicate from this point of view, in particular black.
• cellulose-based textiles preferably cotton-based textiles, dyed in black, in blue, in brown, in green, in a permanent manner, so as to enable the production of items of clothing (such as trousers, shirts, jackets, coats, overcoats) that can resist a large number of domestic washing operations in a washing machine, keeping their original color both from a qualitative and from a quantitative point of view.
• Cotton textile dyeing (cotton and/or cotton mixture) with reactive dyes is generally undertaken in "open width” mode (meaning that the textile is dyed keeping it spread in all its width), preferably with pad batch and pad steam techniques.
• a disadvantage of the two techniques referred to above consists in that none of said two methods can ensure a high dye penetration into textile fibers, even though process operating parameters are changed.
• this method is however characterized by huge problems concerning textile appearance after dyeing (for instance abrasions and possibly an imperfect homogeneity in color distribution).
• permanently dyed refers to textiles or items of clothing and/or fabrics with properties of color solidity and non-degradability as referred to above, in particular textiles resisting to a large number of domestic washing operations keeping their original color.
• a permanently dyed textile refers to a cellulose-based textile having a color degradation after repeated washing operations not below degree 3 of the gray scale for color variation, according to international norm ISO 105 A02, or to the corresponding Italian norm UNI EN 20105 A02/'96 .
• the number of said repeated washing operations is not below 5.
• An aim of the present invention is to provide a cellulose-based textile with properties of color solidity and non-degradability as referred to above.
• Another aim of the present invention is to provide an industrial method for permanently dyeing cellulose-based textiles, thus enabling to manufacture dyed items of clothing and/or fabrics with properties of color solidity and non-degradability as referred to above.
• An object of the present invention is a method for permanently dyeing cellulose-based textiles, as disclosed in the appended independent claim.
• the dyeing method according to the present invention modifies the original textile in a stable manner and gives it a structural variation so as to alter its chemical and physical properties.
• the cellulose-based textile comprises fibers characterized by free hydroxyl functions giving said textile certain properties.
• said fibers are modified in a stable manner by means of a chemical reaction between the free hydroxyl functions of said fibers and the reactive groups of the dye/s used, thus forming covalent ether-type bonds.
• Chemical modification is obtained after a "substitution" of hydrogen atoms of hydroxyl functions on the fibers.
• the fibers that were originally present in the textile will have an outer surface containing a large number of chromophore groups bonded in a stable manner to said fibers.
• Said reactive dyes are used not as such, but in a first stage of the dyeing step they are used as direct dyes, thus enabling them to penetrate deeply and completely into the textile.
• said dyes are used as reactive dyes, thus enabling them to react with the fiber.
• the first stage of the dyeing process is carried out at the same temperature as or preferably at a higher temperature than the one used in the following second stage of said process, and bath pH is characterized by approximately neutral values.
• bath pH is brought to basic values higher than those of the first stage, thus allowing textile fibers to react with the dye absorbed by said textile.
• the dyeing method according to the present invention includes at least one dyeing step carried out in a dyeing bath comprising at least one reactive dye.
• Said reactive dye is a medium or high temperature dye; preferably a medium temperature dye.
• said dyeing step is carried out with a bath ratio, expressed as kilos of textile per liters of bath water, of 1:2 to 1:5, preferably of 1:2 to 1:3.
• a bath ratio expressed as kilos of textile per liters of bath water, of 1:2 to 1:5, preferably of 1:2 to 1:3.
• said at least one reactive dye is present in an amount of 5 to 20% by weight of dye per liter of bath, referring to the dye in powder form; preferably of 5 to 15%.
• Said dyeing method includes the following stages:
• stage a) is carried out at a bath temperature of 85 to 105°C.
• Stage b) is carried out at a bath temperature of 50 to 75°C; preferably of 60 to 70°C.
• Stage b) is carried out at a bath pH of 10 to 12; preferably of 10.5 to 11.
• said pH value is reached by adding anhydrous sodium carbonate in an amount of 5 g/l of bath, and the necessary amount of NaOH at 30% by weight.
• stage b) The chemical reaction of stage b) lasts at least 60 min; preferably more than 60 min.
• each of the stages a) and b) is carried out by keeping the textile in movement in the dyeing bath, so as to create a deep contact between the fibers of said textile and said at least one reactive dye of the bath, thus enabling on one hand maximum dye penetration into the cellulose fibers of the textile, and on the other hand allowing the dye to chemically react to an exhaustive extent with all free OH groups that are present on said fibers.
• said at least one reactive dye is a medium or high temperature dye; more preferably a medium temperature dye.
• the permanent dyeing method according to the present invention includes the following steps:
• the method according to the present invention further includes the following stage:
• the method according to the present invention further comprises the following operations:
• the method according to the present invention is preferably implemented by using a jigger dyeing machine.
• said dyeing machine is operated in typical flow dyeing conditions, thus privileging the dynamic component of the dyeing process.
• dye penetration into the textile and the contact of said dye with cellulose fibers are favored.
• dyes that are used are those to be applied at medium temperature, belonging to the class of bifunctional dyes, i.e. with two reactive leaving groups for each molecule of dye (such as, only by way of example, Levafix ® dyes).
• said dyes and/or mixtures thereof are chosen among those giving the textile a dark color such as for instance: black, blue, brown, green, red.
• black, blue, brown Preferably black, blue, brown; more preferably black.
• the type and amount of the single dye or dyes is suitably identified and chosen by the dyer depending on the textile to be dyed.
• the dyer will consider on the basis of his professional knowledge: the type of color and tone to be obtained; textile weave (i.e. of the way in which weft yarns weave warp yarns); its surface mass (i.e. the weight of a square meter of textile); its dye absorption capacity.
• the dyeing method according to the present invention is implemented as follows, including the following steps:
• the jigger dyeing machine preferably used for implementing the process according to the present invention, basically comprises two parallel rotary cylinders placed over a tub designed to contain the various baths to be used during the dyeing process.
• the textile after being rolled up on a cylinder (machine loading), is shifted several times in different manners from one cylinder to the other getting through the dyeing bath, thus getting deeply impregnated and reacting with the dye.
• the operating modes of the machine can vary, also to a considerable extent, for each working cycle and are decided by the dyer depending above all on machine load (i.e. on the amount of textile, preferably measured in meters and/or kilos, to be loaded onto the cylinder for every working cycle); said load is directly related to the type of textile used, in particular to its surface mass, i.e. to the weight of a square meter of textile.
• the machine if working at full load, is loaded with 500 to 1,600 m of textile, preferably with 800 to 1,200 m, depending on the type of textile to be treated.
• Said textile has a surface mass of 180 to 600 g/m 2 ; preferably of 200 to 500 g/m 2 ; more preferably of 230 to 400 g/m 2 .
• the textile is preferably contacted with an impregnating aqueous solution comprising;
• Water in said impregnating aqueous solution is in such an amount that bath ratio (kilos of textile/liters of water) varies from 1:2 to 1:5, preferably from 1:2 to 1:3.
• water hardness varies from 0 to 3°F, corresponding to an amount of CaCO 3 of 0 to 3 ppm.
• Said imbibing, dispersing and sequestering agents are suitably chosen among those that are known and can commonly be found on the market to the described purpose.
• agents with a higher purity degree are preferred (by mere way of non-limiting example, in a preferred embodiment the following compounds were used: as imbiber the product known as Erkantol ® ; as disperser the product known as Levegal ® ; as sequestrant the product known as Plexene ® ).
• the impregnating step is preferably carried out in hot conditions, at a temperature of 35 to 65°C, preferably of 45 to 60°C; more preferably of about 50°C.
• the number of runs performed during said step is of 1 to 6; preferably of 1 to 4; more preferably of 1 to 3.
• the speed at which the textile is rolled up between the two cylinders of the jigger machine is of 70 to 200 m/min; preferably of 90 to 160 m/min; more preferably of 110 to 140 m/min.
• a series of sequential stages is preferably carried out, comprising:
• Stages a) to f) can be performed as a continuous sequence with the textile always moving, or preferably separately one from the other, so as to prevent as much as possible problems related to selvedge center (i.e. problems of non-uniformity of dye on the whole textile width) and to head-tail (i.e. problems of non-uniformity of dye on the whole textile length), the textile being still and completely rolled up on one of the two cylinders or moving depending on the working step.
• selvedge center i.e. problems of non-uniformity of dye on the whole textile width
• head-tail i.e. problems of non-uniformity of dye on the whole textile length
• the textile is rolled up on one of the two cylinders of the machine, and reagent addition as well as bath temperature regulation take place with still textile (preferably, the textile oscillating on itself at low speed).
• the textile is turned in the bath at least until its temperature is balanced with the temperature of said bath.
• stage f) the textile is turned in said basic bath for at least 60 min, preferably even longer, so as to ensure that the dye has completely reacted with the cellulose fibers of the textile.
• the number of runs for every single stage b) to f) varies much, independently for every stage, depending on the dye and on the amount and type of textile undergoing dyeing. Said number is basically decided by the skilled technician for every specific case, taking into account the operating parameters mentioned above.
• said number can vary from 1 to 10.
• It preferably varies from 1 to 8; still more preferably from 2 to 6; from 2 to 5; from 3 to 4.
• the dyed textile is washed with cold water several times.
• a rinsing cycle with water is preferably alternated to a rinsing cycle with acidulous water so as to neutralize the textile.
• said rinsing step includes the following stages:
• said series of stages g) to i) can be repeated more than once depending on dye persistency in the rinsing bath.
• the number of runs per single rinse is of 2 to 5, preferably of 2 to 4.
• the textile undergoes a given number of treatments with soaped water, which number varies depending on the textile and dye, until soaping water is almost colorless.
• soap is added to washing water in an amount of 0.5 to 4 g/1; preferably of 1.5 to 3 g/1; more preferably of 2 g/1.
• Washing is preferably carried out at a bath temperature of 85 to 100°C; preferably of 90 to 100°C; more preferably of 95°C.
• the number of runs for every single washing and rinsing operation is of 1 to 3, preferably of 1 to 2.
• the textile is rinsed with cold water and sent to following operations.
• the textile is unloaded, dried and sent to current steps involving control and physical treatment for giving it the desired dimensional stability to washing.
• Said steps generally vary depending on the textile and comprise for instance:
• the method according to the present invention is preferably used for dyeing cotton-based textile (meaning by "cotton-based textiles”: 100% cotton, cotton mixture textile with natural and/or artificial cellulose fibers and/or other artificial fibers commonly used in the tailoring field).
• Said textiles can also be elasticized by adding a suitable amount of elastic fiber.
• said textile is an orthogonal textile (i.e. with weft and warp).
• the textile according to the present invention is a permanently dyed textile, having a chemically modified cellulose base as previously described, with a color degradation after repeated washing operations not below degree 3 of the gray scale for color variation.
• said color degradation is between degree 4 to the maximum value, i.e. degree 5, of said gray scale.
• said color degradation corresponds to degree 4/5 of said gray scale.
• the number of repeated washing operations undergone by the textile according to the present invention is not below 5. Preferably, it is of 10 to 50; more preferably of 15 to 25.
• the textile according to the present invention is preferably dyed in a permanent manner with a dark color; said color is preferably black, blue, brown, green; more preferably black.
• said textile is made up of 98% cotton and of 2% elastam.
• the Applicant has carried out a series of comparison tests between black trousers manufactured with a textile dyed with the method according to the present invention and between similar black trousers manufactured with the same textile dyed with the following dyeing techniques as are known in the field.
• the number of repeated washing operations performed on trousers dyed according to the present invention has been increased up to 50 washing operations. Tests have been carried out after 25 and after 50 washing operations.
• trousers manufactured with textiles dyed with techniques [ii] and [iii] have shown the same reaction to washing - if not worse - as the trousers manufactured with a textile dyed with technique [i].
• the method according to the present invention enables to manufacture cellulose-based textiles, preferably cotton-based textiles, dyed in a permanent manner and provided with a higher richness and depth of reflections, especially as far as dark colors are concerned.
• the present invention therefore relates to said dyeing method and to permanently dyed textiles obtained with said method, and to the use of said textiles for manufacturing permanently dyed items of clothing and/or fabrics.
• the present invention also relates to items of clothing and to fabrics manufactured with said textiles.
• the present invention relates to shirts made of cotton or cotton mixture, permanently dyed in black, blue, brown or green.
• the present invention relates to trousers made of cotton or cotton mixture, elasticized if necessary, permanently dyed in black, blue, brown or green.
• the present invention relates to jackets, coats, overcoats made of cotton or cotton mixture, permanently dyed in black, blue, brown or green.
• the present invention relates to skirts made of cotton or cotton mixture, permanently dyed in black, blue, brown or green.

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• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Coloring (AREA)
• Treatments For Attaching Organic Compounds To Fibrous Goods (AREA)

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• 2005
  • 2005-03-04 WO PCT/IT2005/000122 patent/WO2006092815A1/en not_active Application Discontinuation
  • 2005-03-04 AT AT05734830T patent/ATE412798T1/de not_active IP Right Cessation
  • 2005-03-04 EP EP05734830A patent/EP1723280B1/en not_active Revoked
  • 2005-03-04 DK DK05734830T patent/DK1723280T3/da active
  • 2005-03-04 DE DE602005010670T patent/DE602005010670D1/de active Active

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