Dyeing process for protein-based natural fibers with fluorescent properties

Description

Technical field

[0001] This invention relates to a dyeing method for fibres, yarns, fabrics and garments, in particular for protein-based natural fibres, to obtain fibres, yarns, fabrics and garments with fluorescent properties. In particular, the invention relates to a cold dyeing method characterised by temperatures of below 60°C with an overall treatment time of less than two hours and which does not use strong mineral acids. In more detail, the method according to the invention directly uses fluorescent dyes, preferably acid dyes belonging to group I, either in their soluble form or in the form of fluorescent hybrid pigments, the latter comprising an inorganic carrier and an organic component belonging to fluorescent dyes, preferably acid dyes belonging to group I. The method according to the invention uses previously hydrolysed organo-functionalised siloxanes as a binding agent to covalently fix fluorescent dyes or fluorescent pigments on fibres, yarns, fabrics and garments, with the aim of producing textile products with special fluorescent characteristics and high visibility, distinct light stability and excellent wet fastness.Background art.

[0002] The prior art procedures for dyeing protein fibres, shown in Figures 1, 2 and 3, are mainly characterised by the presence of chemical substances, in the first steps of the dyeing, which define the treatment baths as strongly acidic, weakly acidic and neutral [Jose Cegarra, Publio Puente Jose Valdeperas - The dyeing of textile materials - Texilia - Paravia 1988]. These chemical agents are mainly sodium sulphate, sulphuric acid and / or ammonium acetate and their function is to make the protein-based fibre reactive to a particular type of dye belonging to groups I, II or III. The reactivity is guaranteed by a rapid diffusion of the acid substances, with a low molecular weight, towards the carboxylic groups of the fibre which are protonated in this way. Once a high level of protonation has been reached, characterised by the presence of functional groups such as COOH, and taking advantage of the amphoteric nature of the protein fibres, several reactive points are obtained, characterised by the formation of NH 3 +< type groups. This cationic form interacts with the ionic dye (X-), dissolved in the aqueous bath, thus forming an anionic complex with strong electrostatic interaction between the protein-based fibre and the colour. The times and temperatures of the various dyeing baths vary according to the type of dye chosen. In general, all the procedures take longer than one hour, with gradual temperature ramps ranging from 45 minutes to one hour, reaching 100°C as the optimum temperature and thus leading to the so-called boiling of the textile fibre. As shown in Figures 1, 2 and 3 the different methods are, currently, all hot methods and the overall time is more than 2 hours, using very strong chemicals such as sulphuric acid. Moreover, currently, the dyeing of natural fibres with bright colours, called fluorescent or Neon, is carried out by applying for each type of fibre an ad-hoc method which is compatible both with the fibre and with a certain class of colours (for example, acid colours are used to dye wool but not cotton). This approach led to the definition of different dyeing classes for fibres, where each one takes certain conditions of time, temperature, bath pH, concentration, presence or absence of additives designed to increase the fastness and equalise the dyeing [Dyeing Textiles Paravia and Texilia 1988].

[0003] In the specific case of wool, the dyeing is carried out with fluorescent colours belonging to the group I (acids) achieving results which are substantially satisfactory for the different levels of fastness required.

[0004] Table 1 below shows the fastness values of the most common acid fluorescent colours (Group I) currently available on the market. Table 1Fastness parameter Wool Fuchsia Fluo Xenon Lamp with artificial light ISOB011-2Dry rubbing ISO 105:123-4alkaline sweat ISO 105 E042-3acid sweat solution ISO 105 E042-3with salivaNDwater-based ISO 105 E013-4

[0005] Several attempts have been made both to increase light fastness and to dye synthetic and natural fibres with neon or fluorescent colours. However, the values given in the table above represent the best results obtained by applying the prior art technique; as can be seen, for example, low wet fastness is obtained (2-3 out of 5).

[0006] The dyeing of protein fibres can be performed with different classes of dyes. Each class of dyes has its own particular operating conditions. The three classes of acids for wool force dyers to have for each class their own chemical auxiliaries (acids and / or salts), dyestuffs and dyeing profiles with a high expenditure of thermal energy over time. Moreover, keeping the material at high temperatures for a long time also leads to a deterioration of the physical-mechanical qualities of the fibres.

[0007] Dyeing of natural protein fibers with fluorescent dyes intercalated into lamellar solids is disclosed in EP-A-2628849 and dyeing method to improve fastnesses by pretreatmet with a siloxane agent is disclosed in GB-A-942586.Disclosure of the invention.

[0008] Therefore, the technical problem raised and solved by the invention is that of providing an innovative method for dyeing textile yarns which allows the above-mentioned drawbacks of the prior art to be overcome.

[0009] This problem is overcome by a method according to claim 1. Preferred features of the invention are present in the dependent claims.

[0010] The invention aims to provide a bland dyeing method, unique for all types of protein fibres, which allows fluorescent pigments, fluorescent dyes and fluorescent brightening to be covalently bound in clothing textiles and ensuring a distinct light fastness and excellent washing fastness.

[0011] Advantageously, the method according to the invention achieves the following benefits: the chemical products required are drastically reduced, resulting in lower operating and purchasing costs; by reducing chemical products, the pollutants in the water are reduced; reduction of energy costs; reduction of process times; greater respect and preservation of the physical-mechanical properties of textile yarns.

[0012] In particular, the invention relates to an innovative dyeing method, wherein a dyed and / or raw natural fibre yarn is dyed with fluorescent dyes or with a fluorescent pigment comprising fluorescent dyes. This fluorescent pigment is a 2D nanostructured pigment with optimised optical activity. In particular, when the term 'fluorescent pigment' is used in the invention, it means a hybrid pigment with optimised optical activity consisting of an organic fluorescent molecule, for example, an acid fluorescent dye of group I, intercalated or absorbed in an inorganic system, in which the organic fluorescent molecule, in its anionic form, has been intercalated and / or absorbed in the inorganic system by direct reactions or by means of intermediaries. Said inorganic system is a lamellar solid, preferably of the layered double hydroxides type - LDH, more specifically belonging to the hydrotalcites family.

[0013] The dyeing method according to the invention makes it possible to obtain a nano-coating or surface coating of fluorescent dye or fluorescent pigment on the fibre in a single step and under bland conditions (below 60°C), through the formation of a covalent bond between the fibre and the fluorescent dye or between the fibre and the fluorescent pigment, regardless of the type of fibre or textile clothing product. This allows the fluorescence characteristics to be transferred to the natural fibre. The result of the dyeing method according to the invention is a fluorescent textile clothing product with high visibility, high wet fastness and distinct light fastness. The method according to the invention is suitable for dyeing fibres, yarns, fabrics and garments made of protein-based natural fibres, such as wool, cashmere, mohair, angora, silk and related blends of the above-mentioned fibres.

[0014] The aim of the invention is to provide a unique and universal dyeing method which groups together all the dyeing classes currently existing for natural protein fibres into a single operational method.

[0015] In particular, the dyeing method according to the invention uses a fluorescent dye or a fluorescent pigment which, when fixed to a textile product, transfers the above-mentioned fluorescent activity to the textile substrate, providing a fluorescent textile product which preserves the fluorescent characteristics of the dye or the starter pigment and is characterised by an access colour with high visibility and homogeneity.

[0016] The invention therefore proposes an innovative dyeing procedure based on the formation of covalent bonds between a fluorescent dye or the inorganic part of a fluorescent pigment and the functional groups of a natural textile substrate, such as primary and secondary amine, hydroxyl and carboxylic groups. The covalent bond is preferably formed by the reaction between reactive organo-functional siloxane agents (adhesion promoters) and natural fibres such as wool, silk, mohair, cashmere and their mixtures and fluorescent dyes or pigments in water under mild thermal conditions. When the fluorescent pigment or fluorescent dye is used, the mild heat treatment according to the invention promotes the formation of a rapid condensation reaction between the hydroxyl groups of the inorganic part or the reactive groups of the fluorescent dye and the functional groups present in the natural fibres (hydroxyl, carboxyl and primary and secondary amine), mediated by the presence of an additive which promotes adhesion. More specifically, the various organic functions (amine, epoxy, alkoxide) contained in the adhesion promoter additive are able to react in the medium, producing by-products such as diols and alcohols, and covalently bind the textile fibres with the fluorescent pigments or dyes used. The dyed product thus obtained is highly resistant to further hydrolysis and washing reactions.

[0017] The method according to the invention is advantageously innovative in terms of the method and stage of application of the organo-functioning siloxanes in the presence of fluorescent dyes or fluorescent pigments.

[0018] The combination of the beneficial effect of the dyeing method according to the invention on the preservation of the physical, chemical and structural properties of the natural fibre together with the reflective UV effect of the inorganic protective systems against interspersed and / or absorbed dyes [D.Yan, M. Wei, Photofunctional Layered Materials, Structure and Bonding 166 Springer International Publishing 2015] advantageously allows a highly visible textile garment product to be obtained which preserves the fluorescent characteristics of the starter acid dye and is characterised by distinct light stability and excellent wet fastness. These characteristics are significantly better with respect to the same characteristics found in products dyed with the prior art dyeing processes.

[0019] The dyeing method according to the invention makes it possible to obtain a textile product with characteristics of high visibility and fluorescence when irradiated with UV light and high thermal, photochemical and washing stability.

[0020] The dyeing method according to the invention advantageously allows excellent light fastness and wet fastness values to be obtained, which comply with the Chinese standard GB 18401 for products for adults. The fastness values obtained by applying the method according to the invention to a wool yarn are shown in Table 2. Table 2Fastness parameter Wool Xenon Lamp with artificial light ISOB012-3Dry rubbing ISO 105:124-5alkaline sweat ISO 105 E044-5acid sweat solution ISO 105 E044-5with saliva4-5

[0021] The dyeing method according to the invention also makes it possible to preserve the noble characteristics of the natural fibres, such as softness and brilliance, as the dyeing operations are carried out at temperatures not exceeding 60°C and in less than 2 hours. There are no other additives / reagents such as sulphuric acid, acetic acid, equalising agent, formic acid, ammonium acetate, ammonium sulphate and there is a reduced number of operations, which are also fully compatible with current industrial procedures for dyeing skeins and / or spools. Moreover, the temperature ramp is fast and fully compatible with the normal operations of adding of the yarn to be treated, dispersing the pigment or dye and adding the siloxane binding agent, all in a time not exceeding 15 - 25 mins. A further advantage of the dyeing method according to the invention is that it does not discriminate the type of fluorescent pigment, so the same procedure can be applied for pigments based on lamellar solids type LDH and Zr phosphates.Brief description of the drawings

[0022] The invention will be now described, by an illustrative, but not limitative way, according to preferred embodiments thereof, with particular reference to the examples and the enclosed drawings, wherein: Figure 1 shows a known dyeing process of wool in a strongly acidic bath; Figure 2 shows a known dyeing process of wool in a weakly acidic bath; Figure 3 shows a known dyeing process of wool in a neutral bath; Figure 4 shows a schematic view of an application example of the tracer dyeing process according to the invention. A: immersion of the wool yarn in purified water and addition of the siloxane agent; B: addition of the fluorescent pigment or colour. Figure 5 shows the XRD diffractogram of the ZnAl_Yellow pigment shown in Example 5; Figure 6 shows the thermogravimetric analysis of the ZnAl_Yellow pigment shown in Example 5; Figure 7 shows the XRD diffractogram of the ZnAl_Magenta pigment shown in Example 6; and Figure 8 shows the thermogravimetric analysis of the ZnAl_Magenta pigment shown in Example 6. Detailed description of the invention and preferred embodiments

[0023] The specific object of the invention is therefore a dyeing method for colouring or dyeing a protein-based natural fibre by means of a fluorescent dye or a fluorescent pigment, comprising the steps of: a) preparing a natural fibre in a dyeing tank with water; b) adding a siloxane agent in said tank; c) dispersing a liquid colouring solution comprising a fluorescent dye or fluorescent pigment in said tank; d) heating said dyeing tank comprising said natural fibre, said siloxane agent and said colouring solution at a temperature comprised between 50°C and 70°C, preferably at 60°C; e) keeping said temperature constant for a time comprised between 1 and 3 hours. Advantageously, the fluorescent pigment is a pigment, comprising: an inorganic matrix having a lamellar conformation, an organic fluorescent filler configured to be intercalated or absorbed between the lamellae of said inorganic matrix.

[0024] The organo-functionalised siloxane-based binding agent, for example previously hydrolysed, is used to create a coating to the support, meaning yarn, fibre, fabric or garment.

[0025] More specifically, when the dyeing method is carried out using dyes which are soluble in the dyeing bath, the siloxanes can be added to the dyeing bath even before the dyes.

[0026] When, on the other hand, a pigment is used which is insoluble in the dyeing bath because it is a solid material, the siloxane must be added to the dyeing bath before the pigment is inserted so that it can be fixed on fibres, yarns, fabrics and garments.

[0027] More specifically, the siloxane agent is added in said tank in a percentage by weight less than or equal to 10% by weight of the fibre, preferably between 0.1% and 5% when a fluorescent dye is used and between 5% and 10% when a fluorescent pigment is used.

[0028] The siloxane agent is chosen, for example, from amine / epoxy / octyl / methoxy / ethoxy functionalised hydrolysed siloxane agents such as Dynasylan Hydrosil 1153, Dynasylan Hydrosil 2627, Dynasylan Hydrosil 2926, Dynasylan Hydrosil 2776, Dynasylan Hydrosil 2909 (Evonik commercial products).

[0029] Preferably, the liquid colouring solution comprises a mixture of purified water and fluorescent dye or purified water and fluorescent pigment wherein the quantity of fluorescent dye or fluorescent pigment with respect to the amount of water is between 5-15 grams of pigment per litre of water.

[0030] Preferred embodiments comprise a liquid colouring solution with a percentage by weight of fluorescent dye or fluorescent pigment of between 0.1% and 5%, with respect to the weight of the natural fibre, preferably approximately 2% fluorescent pigment or approximately 0.25% fluorescent dye.

[0031] Subsequently, the dyeing process according to the invention comprises the immersion of the fibres, yarns, fabrics and / or garments in the dyeing bath.

[0032] The dyeing bath comprising said fibre, said siloxane agent and said colouring solution is then homogenised, in particular for a time comprised between 10 and 20 minutes for the phase relating to yarn plus siloxane agent homogenisation. Subsequently, the dyeing bath is brought to a temperature of 60°C for a period of time between 1 and 3 hours, preferably 2 hours. Finally, the overpressure dyeing bath is drained and the fibre is rinsed three times.

[0033] The result is a fibre, yarn, fabric and / or garment with the fluorescent dye or fluorescent pigment covalently bonded and optically active to UV radiation.

[0034] More specifically, the natural fibre, preferably in a configuration wound on a spool, or reel, or skein, is placed in water, with a ratio between said fibre and said water of between 1 mg / ml and 20 mg / ml.

[0035] The pH is advantageously kept equal to the isoelectric point of the natural fibre, for example at a value of approximately 4.7.

[0036] In a preferred form of the method according to the invention fluorescent pigments are used wherein the inorganic matrix comprises components belonging to the hydrotalcite group, in particular layered double hydroxides (LDH), optionally MgAl and ZnAl, or lamellar solids such as zirconium phosphates.

[0037] More specifically, the organic molecule of the fluorescent pigment comprises: fluorescent dyes such as Sodium 2-[7-(diethylamine)-2-oxo-2H-chromen-3-yl]-5-sulfamoyl-2, 3-dihydro-1 ,3-benzoxazole-2-sulfonate (CAS 93859-32-6) (Yellow Fluo Cromacid 8GX) and Sulforhodamine B sodium salt (CAS 3520-42-1)(Red Fluo Cromacid B), optical brighteners or bleaches such as Fluorescent Brightener, optionally Fluorescent Brightener 351, or Group I acid dyes, stilbene dyes, rhodamine dyes and dyes based on benzoxazole derivatives.

[0038] For example, the fluorescent pigment may be composed of an inorganic component of the lamellar solids type belonging to the family of layered double hydroxides (LDH) known as hydrotalcite, with the formula [M2+1-xM3+x(OH)2][An-]x / n-zH2O (3:1 Mg / Al ratio, co-intercalated with counterion nitrate and / or carbonate and / or water molecules), absorbed with the organic molecule belonging to the family of acid fluorescent dyes of the group I 4 Sulforhodamine B sodium salt (CAS 3520-42-1)(Red Fluo Cromacid B). Once the pigment has been fixed on the textile fibre according to the dyeing method of the invention, the clothing textile product has high visibility, is characterised by a fluorescence when irradiated with UV light and has distinct fastness to light and excellent fastness to wet treatments.

[0039] Alternatively, the fluorescent pigment may be composed of an inorganic component of the lamellar solids type belonging to the family of layered double hydroxides (LDH) known as hydrotalcite, with the formula [M2+1-xM3+x(OH)2][An-]x / n-zH2O (3:1 Mg / Al ratio, co-intercalated with counterion nitrate and / or carbonate and / or water molecules), absorbed with the organic molecule belonging to the family of the acid fluorescent dyes (benzoxazole derivative) Sodium 2-[7-(diethylamino)-2-oxo-2H-chromen-3-yl]-5-sulfamoyl-2,3-dihydro-1,3-benzoxazole-2-sulfonate (CAS 93859-32-6) (Yellow Fluo Cromacid 8GX). Also in this case, once the pigment has been fixed on the textile fibre according to the dyeing method of the invention, the clothing textile product has high visibility, is characterised by a fluorescence when irradiated with UV light and has distinct fastness to light and excellent fastness to wet treatments.

[0040] In an alternative embodiment of the method according to the invention, a fluorescent dye is used chosen from fluorescent dyes such as Sodium 2-[7-(diethylamine)-2-oxo-2H-chromen-3-yl]-5-sulfamoyl-2,3-dihydro-1,3-benzoxazole-2-sulfonate (CAS 93859-32-6) (Yellow Fluo Cromacid 8GX) and Sulforhodamine B sodium salt (CAS 3520-42-1)(Red Fluo Cromacid B), optical brighteners or bleaches such as Fluorescent Brightener, optionally Fluorescent Brightener 351, or Group I acid dyes, stilbene dyes, rhodamine dyes and dyes based on benzoxazole derivatives.

[0041] The dyeing method according to the invention increases the compatibility between the textile product and the fluorescent dye or fluorescent pigment, as it allows the formation of a thermally stable covalent bond, formed by condensation reactions between the hydroxyl groups (-OH) of the inorganic part or the reactive groups of the fluorescent dye with the functional groups present on the natural fibres (hydroxylic, carboxylic, primary amine and secondary amine), mediated by the presence of an adhesion promoting additive, such as siloxane agents with reactive functions. Preferably, according to the invention, an adhesion promoter based on siloxane oligomers reactive in aqueous medium, activated at a temperature below 60°C, is used.

[0042] Advantageously, in the dyeing method according to the invention, there are no other additives / reagents such as sulphuric acid, acetic acid, equalising agent, formic acid, ammonium acetate, ammonium sulphate and there is a reduced number of operations, which are also fully compatible with current industrial procedures for dyeing skeins and / or spools.

[0043] Moreover, the temperature ramp is fast and fully compatible with the normal operations of adding the yarn to be treated, dispersing the pigment or dye and adding the siloxane bonding agent, all in a time not exceeding 15 - 25 mins. For example, as can be seen from Figure 4, which shows a diagram of the method according to the invention in which a wool yarn is used and a siloxane bonding agent Hydrosyl 2926 of between 5 and 10% by weight with respect to the weight of the fibre and a fluorescent acid dye or a smart pigment of between 0.25 and 2% by weight with respect to the weight of the fibre, the maximum dyeing temperature applied in the method according to the invention represents the minimum temperature used in the traditional methods shown in Figures 1, 2, and 3.

[0044] The invention also relates to a textile product made of protein-based natural fibres with fluorescent properties, comprising a fluorescent dye or fluorescent pigment as defined above, wherein said fluorescent dye or fluorescent pigment is bound to the protein-based natural fibre by a covalent bond.

[0045] More specifically, a garment textile product having fluorescent properties, dyed with a dye or organic component belonging to the family of acid fluorescent dyes of group 1, preferably Sodium 2-[7-(diethylamino)-2-oxo-2H-chromen-3-yl]-5-sulfamoyl-2,3-dihydro-1,3-benzoxazole-2-sulfonate (CAS 93859-32-6) (Yellow Fluo Cromacid 8GX) or - Sulforhodamine B sodium salt (CAS 3520-42-1)(Red Fluo Cromacid B), covalently bound to the fibre by the dyeing method according to the invention, which is a highly visible garment textile product, characterised by a fluorescence when irradiated under UV light and excellent fastness to wet treatments.

[0046] Moreover, the invention relates to a garment textile product having fluorescent properties, dyed with an optical brightener or organic component belonging to the family of fluorescent optical brighteners preferably Fluorescent Brighter 351, covalently bonded to the fibre by the dyeing method according to the invention, which results in a garment textile product characterised by a fluorescence when irradiated under UV light and of distinct light fastness and excellent fastness to wet treatments.EXAMPLE 1. Example of the dyeing method according to the invention.

[0047] The method for dyeing yarns according to the invention described below is a spool or skein dyeing process compatible with an industrial process (Process A) and comprises the following steps: 1. Inserting the spool or skein into the dyeing tank; 2. Cold rinsing; 3. Pre-setting "cold washing / dyeing cycle". Bath ratio 1:17; 4. Checking pH (value approx. 4.7). The best pH conditions for dyeing are the isoelectric conditions of the fibre, where the -OH groups are not deprotonated; 5. Solubilising and / or dispersing in purified water an acid dye (30 g in 3.5 litres of water); using from 0.1 to 5%, preferably 0.25% per colour, by weight with respect to the weight of the fibre, before step 6; or solubilising and / or dispersing in purified water a fluorescent pigment (30 g in 3.5 litres of water) using from 0.1 to 5%, preferably 2% by weight with respect to the weight of the fibre, after step 6; 6. Adding the siloxane agent directly to the bath, in a quantity of up to 10% with respect to the weight of the fibre; preferably between 0.1 and 5% by weight for the acid dye and between 5 - 10% by weight for the fluorescent pigment. 7. Homogenising the dyeing bath for 10-20 minutes 8. Dosing the solution / dispersion made in step 5 in the tank containing the yarn and the siloxane agent; 9. Heating to 60°C; 10. Leaving in treatment at 60°C for 1 hour; preferably 2 hours. 11. Discharging; 12. Rinsing 3 times. EXAMPLE 2: Method of dyeing, according to present invention, natural protein fibres (wool) with fluorescent pigments LDH_Red_1 and LDH_Yellow_1.

[0048] The fluorescent pigments used, named LDH_Red_1 and LDH _Yellow_1, consist, respectively, of the organic molecules Sulforhodamine B sodium salt (CAS 3520-42-1) (Fluo Red Cromacid B - Fuchsia) and Sodium 2-[7-(diethylamino)-2-oxo-2H-chromen-3-yl]-5-sulfamoyl-2,3-dihydro-1,3-benzoxazole-2-sulfonate (CAS 93859-32-6) (Fluo Yellow Cromacid 8GX). Both dyes have been absorbed in a precursor hydrotalcite type Aluminium Magnesium Hydroxide Nitrate-LDH_NO3 (CAS 148884-57-5). Colorimetric characteristics of the fluorescent pigment named LDH_Red 1 Colour - CIELab colour coordinateL = 20.90 a' =38.3 b' =-3.5 Colorimetric characteristics of the pigment named LDH_Yellow 1 Colour - CIELab colour coordinateL =56.42; a' =14.5; b' =64.3

[0049] The resulting pigments were applied to wool fibres according to the method described in Example 1.Test results Wool yarns dyed with fluorescent pigment LDH_Red 1

[0050] ISO 105 B02: 2014 - Colour fastness to artificial light: Test with xenon arc lamp Degradation value: 1 / 2 ISO 105 C06: 2010 - Colour fastness to domestic and commercial washing Degradation value: 4-5 Wool yarns dyed with fluorescent pigment LDH_Yellow 1

[0051] ISO 105 B02: 2014 - Colour fastness to artificial light: Test with xenon arc lamp Degradation value: 1 / 2 ISO 105 C06: 2010 - Colour fastness to domestic and commercial washing Degradation value: 4-5 EXAMPLE 3. Method of dyeing, according to the invention, for natural protein fibres (wool) with Red Fluo Cromacid B and Yellow Fluo Cromacid 8GX.

[0052] The wool protein fibre was dyed, according to the method shown in Example 1, with the fluorescent dyes Sulforhodamine B sodium salt (CAS 3520-42-1)(Fluo Red Cromacid B) and Sodium 2-[7-(diethylamino)-2-oxo-2H-chromen-3-yl]-5-sulfamoyl-2,3-dihydro-1,3-benzoxazole-2-sulfonate (CAS 93859-32-6) (Fluo Yellow Cromacid 8GX), respectively.Test results Wool yarns dyed with Red Fluo Cromacid B (Fuchsia)

[0053] ISO 105 B02: 2014 - Colour fastness to artificial light: Test with xenon arc lamp Degradation value: 2 / 3+ ISO 105 C06: 2010 - Colour fastness to domestic and commercial washing Degradation value: 4-5 Wool yarns dyed with Yellow Fluo Cromacid 8GX

[0054] ISO 105 B02: 2014 - Colour fastness to artificial light: Test with xenon arc lamp Degradation value: 2 / 3+ ISO 105 C06: 2010 - Colour fastness to domestic and commercial washing Degradation value: 4 / 5 EXAMPLE 4. Method of dyeing, according to the invention, natural protein fibres (wool) with Fluorescent Brightener 351 (CAS 27344-41-8).

[0055] The wool protein fibre was dyed with Fluorescent Brightener 351 (CAS 27344-41-8).Test results.

[0056] ISO 105 B02: 2014 - Colour fastness to artificial light: Test with xenon arc lamp Degradation value: 1 / 2 ISO 105 C06: 2010 - Colour fastness to domestic and commercial washing Degradation value: 3 / 4

Claims

1. A dyeing method for colouring or dyeing a protein-based natural fibre by means of a fluorescent dye or a fluorescent pigment, comprising the following steps: a) preparing a natural fibre in a dye tank with water; b) adding a siloxane agent in said tank; c) dispersing a liquid colouring solution comprising a fluorescent dye or fluorescent pigment in said tank; d) heating said dye tank comprising said natural fibre, said siloxane agent and said colouring solution at a temperature of between 50°C and 70°C, preferably at 60°C; e) keeping said temperature constant for between 1 and 3 hours; wherein said fluorescent pigment is a pigment, comprising: - an inorganic matrix having a lamellar conformation, - an organic fluorescent filler configured to be intercalated or absorbed between the lamellae of said inorganic matrix.

2. The dyeing method according to the previous claim, wherein said liquid colouring solution comprises a mixture of purified water and fluorescent dye or purified water and fluorescent pigment wherein the quantity of fluorescent dye or fluorescent pigment with respect to the amount of water is between 5-15 g of pigment per litre of water.

3. The dyeing method according to any one of the preceding claims, wherein said liquid colouring solution comprises a percentage by weight of fluorescent dye or fluorescent pigment of between 0.1% and 5%, with respect to the weight of the natural fibre, preferably approximately 2% fluorescent pigment or approximately 0.25% fluorescent dye.

4. The dyeing method according to any one of the preceding claims, wherein said siloxane agent is added in said tank in a percentage by weight less than or equal to 10% by weight of the fibre, preferably between 0.1% and 5% when a fluorescent dye is used and between 5% and 10% when a fluorescent pigment is used,5. The dyeing method according to any one of the preceding claims, further comprising homogenising a dyeing bath comprising said fibre, said siloxane agent and said colouring solution.

6. The dyeing method according to the previous claim, wherein said homogenising step is carried out for between 10 and 20 minutes.

7. The dyeing method according to any one of the preceding claims, wherein in said step (a) said natural fibre is placed in water, wherein the ratio between said fibre and said water is between 1 mg / ml and 20 mg / ml.

8. The dyeing method according to any one of the preceding claims, wherein the pH is kept equal to the isoelectric point of the natural fibre.

9. The dyeing method according to any one of the preceding claims, wherein the pH is kept at a value of approximately 4.7.

10. The dyeing method according to any one of the preceding claims, wherein said fibre is in a configuration wound on a spool, or reel, or skein.

11. The dyeing method according to any one of the preceding claims, wherein said inorganic matrix of said fluorescent pigment includes components belonging to the hydrotalcite group.

12. The dyeing method according to the previous claim, wherein said components belonging to the hydrotalcite group are layered double hydroxides (LDH), preferably MgAl and ZnAl, or lamellar solids, preferably zirconium phosphates.

13. The dyeing method according to any one of the preceding claims, wherein said organic fluorescent filler of the fluorescent pigment comprises: fluorescent dyes, preferably Sodium 2-[7-(diethylamine)-2-oxo-2H-chromen-3-yl]-5-sulfamoyl-2,3-dihydro-1,3-benzoxazole-2-sulfonate (CAS 93859-32-6) and Sulforhodamine B sodium salt (CAS 3520-42-1), optical brighteners or bleaches, preferably Fluorescent Brightener, more preferably Fluorescent Brightener 351, or Group I acid dyes, stilbene dyes, rhodamine dyes and dyes based on benzoxazole derivatives.

14. The dyeing method according to claims 1-12, wherein said fluorescent dye is selected amongst fluorescent dyes, preferably Sodium 2-[7-(diethylamine)-2-oxo-2H-chromen-3-yl]-5-sulfamoyl-2,3-dihydro-1,3-benzoxazole-2-sulfonate (CAS 93859-32-6) and Sulforhodamine B sodium salt (CAS 3520-42-1), optical brighteners or bleaches, preferably Fluorescent Brightener, more preferably Fluorescent Brightener 351, or Group I acid dyes, stilbene dyes, rhodamine dyes and dyes based on benzoxazole derivatives.

15. The dyeing method according to any one of the preceding claims, wherein said siloxane agent is selected from amine / epoxy / octyl / methoxy / ethoxy functionalised hydrolysed siloxane agents.