Method of dyeing a touch fastener strip

Abstract

The invention relates to a method for dyeing a hook and loop fastener tape 12, wherein the hook and loop fastener tape 12 continuously passes through a basic or neutral dyeing solution 38 in a dyeing device 36. The dyeing solution 38 adheres to the hook and loop fastener tape 12. The dyeing solution 38 comprises a dye 40 that only bonds to the hook and loop fastener tape 12 when the dyeing solution 38 is in an acidic state. After passing through the dyeing device 36, the hook and loop fastener tape 12 with the attached dyeing solution 38 is passed through a steamer 52, causing the dyeing solution 38 to become acidic. The dye 40 adheres to the hook and loop fastener tape 12 to dye the hook and loop fastener tape 12. The invention also relates to a dyeing system 10 for carrying out the method.

Description

Background of the invention

[0001] The invention relates to a method for dyeing a hook-and-loop fastener tape having protruding hooks, mushrooms, and / or loops. The invention further relates to a dyeing system for carrying out the method.

[0002] A method for dyeing textile goods is known from DE 196 10 120 C2. DE 103 34 675 A1 relates to a method for dyeing or printing self-adhesive fasteners. A method for fixing ink to a surface using selected pressure and temperature ranges is disclosed in WO 2008 / 111038 A2.

[0003] EP 0 043 984 A1 relates to a dyeing process for dyeing or printing fiber mixtures of cellulose and polyester fibers using acid donors.

[0004] It is known from the prior art to dye hook-and-loop fastener tapes roll by roll in dyeing vats. The disadvantages of these methods are their comparatively high time expenditure, particularly due to the replacement of the hook-and-loop fastener tapes in the dyeing vats and any subsequent processing required to achieve an even dye application on the hook-and-loop fastener tapes.

[0005] As an alternative to the roll-by-roll dyeing described above, attempts have been made to dye hook-and-loop fastener tapes continuously. However, this is problematic because hook-and-loop fastener tapes have protruding, delicate hooks, mushrooms, and / or loops that are supposed to match the color of the base material they are attached to. To achieve uniform dyeing of these delicate structures and the associated, more solid material, attempts have been made to use thickeners, but this has not been achieved. Object of the invention

[0006] The object of the invention is to provide a method for dyeing a hook-and-loop fastener tape that achieves uniform dyeing of the hook-and-loop fastener tape in a time-saving and reliable manner. It is also an object of the invention to provide a dyeing system for carrying out the method. Description of the invention

[0007] This object is achieved according to the invention by a method according to claim 1. The object is further achieved by a dyeing system according to claim 15.

[0008] The method according to the invention comprises the following successive steps: a) Continuously passing a hook and loop fastener tape through a dyeing device to apply a dyeing solution having a pH of at least 7 to the hook and loop fastener tape, wherein the dyeing solution comprises a dye, wherein the dye is in particular an acid dye that binds to the hook and loop fastener tape at a pH of less than 7; b) Continuously passing the hook and loop fastener tape with the applied dyeing solution through a steamer, wherein the pH of the dyeing solution in the steamer is lowered to below 7 in order to enhance adhesion of the dye to the hook and loop fastener tape.

[0009] The dye in the dyeing solution does not bind directly to the hook and loop fastener tape upon contact. Rather, the dye initially adheres to the hook and loop fastener tape, whereupon the dye is evenly distributed over the surface of the hook and loop fastener tape, for example, through diffusion. The time period during which the dye can spread over the surface of the hook and loop fastener tape can be flexibly adjusted by allowing the hook and loop fastener tape to remain in the dyeing device for a desired period of time. This ensures even distribution of the dye over the surface of the hook and loop fastener tape.

[0010] In the steamer, the dye's adhesion to the hook and loop fastener tape is enhanced without compromising its even distribution. This reliably results in uniform coloring of the hook and loop fastener tape. The dye's adhesion to the hook and loop fastener tape is enhanced, in particular, by lowering the pH value in the steamer to below 7. The dye's adhesion to the hook and loop fastener tape is enhanced, in particular, by the dye binding to the hook and loop fastener tape at a pH value below 7.

[0011] In the case of a dyeing solution containing multiple dyes, this can prevent the dyes in the dyeing solution from adhering to the hook and loop fastener tape at different rates (in particular, from binding to the hook and loop fastener tape) in the dyeing device, causing the dye concentration on the hook and loop fastener tape to deviate from the desired concentration, resulting in an undesirable overall color of the hook and loop fastener tape. Furthermore, the water consumption during the process is comparatively low, allowing the dyeing of the hook and loop fastener tape to be carried out in an environmentally friendly and sustainable manner.

[0012] The hook-and-loop fastener strip is, in particular, one of two strips of a hook-and-loop fastener. In addition to the hook-and-loop fastener strip, the corresponding hook-and-loop fastener has another hook-and-loop fastener strip that is complementary to the hook-and-loop fastener strip to create a hook-and-loop connection between the hook-and-loop fastener strip and the other hook-and-loop fastener strip.

[0013] Bemacid Yellow O, Bemacid Red O and / or Bemacid Marine ® are particularly used as dyes. Preferred dyes, especially acid dyes, are Amido Black 10 B, in particular with the empirical formula disodium 4-amino-5-hydroxy-3-[(4-nitrophenyl)diazenyl]-6-(phenyldiazenyl)-2,7-naphthalenedisulfonate), Acid Yellow 36, in particular with the empirical formula sodium 3-[(4-anilinophenyl)diazenyl]benzenesulfonate), Acid Blue 25, in particular with the empirical formula 1-amino-4-anilino-9,10-dioxoanthracene-2-sulfonic acid (Na salt)) and / or Acid Green 22, in particular with the empirical formula Sodium 3-{[{(1Z,4E)-4-[(2-chlorophenyl){4-[ethyl(3-sulfonatobenzyl)amino]-2-methylphenyl}methylene]-3-methyl-2,5-cyclohexadien-1-ylidene}(ethyl)ammonio]methyl}benzenesulfonate was used.

[0014] Examples of acid dyes are

[0015] During the procedure, steps a) and b) are carried out in particular without interruption, i.e. without any procedural steps being carried out in between.

[0016] In a preferred variant of the method, the dyeing solution comprises an acid dispenser which is designed to release acid at a critical value of a control parameter of the steamer in order to lower the pH value of the dyeing solution in the steamer.

[0017] Acid donors are, in particular, chemical compounds that can form free acids in aqueous solution.

[0018] Carboxylic acid esters are particularly such compounds. Acid-catalyzed hydrolysis of carboxylic acid esters releases the corresponding carboxylic acid, which can lead to a decrease in pH. Acid-catalyzed hydrolysis of esters is particularly temperature-dependent; the reaction rate increases with increasing temperature.

[0019] Meropan EF ®< is in particular a carboxylic acid ester-based acid donor which can lower the pH value of a solution, especially the dyeing solution, at higher temperatures.

[0020] Carboxylic acid esters are organic compounds formed by a reaction between a carboxylic acid and an alcohol, known as esterification. In this reaction, water is released as a byproduct. R1COOH + R2OH --> R1COOR2 + H2O

[0021] Esterification is, in particular, an equilibrium reaction. The reverse reaction of esterification is, in particular, ester cleavage, also known as ester hydrolysis, in which the ester is cleaved into the corresponding carboxylic acid and alcohol.

[0022] During the hydrolysis of esters, the pH value in particular changes, and the nature of the change depends on whether the hydrolysis takes place in an acidic or basic medium.

[0023] In acid-catalyzed hydrolysis for ester cleavage, the ester is treated with water in the presence of an acid, such as sulfuric acid. The equilibrium of this reaction is primarily favored by the carboxylic acid and the alcohol, especially when excess water is used. Acid-catalyzed hydrolysis leads, in particular, to the formation of a free carboxylic acid, which can lower the pH value because carboxylic acids are weak acids and partially dissociate in aqueous solution.

[0024] The general reaction equation is in particular: R1COOR2 + H2O → R1COOH + R2OH

[0025] The Arrhenius equation describes in particular the relationship between the rate constant and the temperature: k = A ⋅ e − Ea RT

[0026] In particular: (A) the pre-exponential factor (frequency factor), (Ea) the activation energy, (R) the general gas constant, (T) the absolute temperature in Kelvin.

[0027] The acid-catalyzed hydrolysis of esters also shows a temperature dependence. The reaction rate increases with temperature, as the protonation of the ester's carbonyl group and the subsequent attack of water on the positively charged carbon are facilitated.

[0028] One of the following substances is preferably used as an acid donor: sodium chloroacetate, sodium dichloroacetate, sodium salt of 3-chloropropionic acid, monochloroacetamide, butyrolactone, lauryl sulfate, hexadecyl sulfate, octadecyl sulfate, 2-ethylhexyl sulfate, butyl sulfate, butylglycol sulfate, butyldiglycol sulfate, C1-C4 alkyl esters of phosphoric acid and / or phosphorous acid, trimethyl phosphate, triethyl phosphate, tris-(hydroxyethyl) phosphate, dimethyl phosphate, diethyl phosphite, dipropyl phosphite, diisopropyl phosphite, dibutyl phosphite, dimethyl methanephosphonate, diethyl ethanephosphonate, trimethyl phosphonopropionate, dimethyl cyanethanephosphonate, dimethyl cyanomethanephosphonate, dimethyl hydroxyethane and / or hydroxymethanephosphonate. 2-Chloroethanephosphonic acid dimethyl ester, 2-Chloroethanephosphonic acid diethyl ester and / or phosphonosuccinic acid tetra-methyl ester.

[0029] Meropan RLS ®< is used in particular as an acid donor.

[0030] In a further development of the aforementioned variant of the method, the control parameter is the temperature of the dye solution in the steamer, with the critical value of the control parameter being in the range of 70°C to 105°C. The temperature as a control parameter can be adjusted relatively easily.

[0031] In the steamer, the temperature rises to over 90°C, and the pH of the dye solution preferably drops to a value below 6. The aforementioned acid dyes, with the sulfonic acid residue as a hydrophilic substituent, are completely dissociated, particularly in this pH range. In particular, the amino groups of the polyamide fibers of the hook-and-loop fastener tape are present as ammonium cations. The dye anions essentially form salt-like bonds with the functional groups of the fiber, particularly during the actual dyeing process.

[0032] In an advantageous variant of the method, the dyeing solution comprises a first masking substance which, in the dyeing device at the starting value of the control parameter, has an affinity to the dye which is greater than the affinity of a hook and loop material of the hook and loop fastener tape to the dye, wherein in the steamer at the critical value of the control parameter the affinity of the first masking substance to the dye is smaller than the affinity of the hook and loop material of the hook and loop fastener tape to the dye.

[0033] In the context of the invention, the affinity of one substance to another is understood in particular as the tendency of the substances to bond to one another. The first masking substance attaches itself to molecules of the dye in the dyeing device, thereby preventing the dye from adhering to the hook-and-loop material of the hook-and-loop fastener tape. The first masking substance thus also prevents the dye from bonding to the hook-and-loop fastener tape in the dyeing device. In the steamer, the first masking substance releases the dye, allowing the dye to bond to the hook-and-loop fastener tape.

[0034] The hook and loop fastener tape consists, in particular, of the hook and loop material of the hook and loop fastener tape with the aforementioned affinity or bonding properties. The hook and loop material preferably contains fibers. Sarabid IPD® is used as the first masking material.

[0035] A preferred variant of the method is one in which the dyeing solution comprises a second masking substance which, in the dyeing device at the starting value of the control parameter, has an affinity to a hook and loop material of the hook and loop fastener tape which is greater than the affinity of the dye to the hook and loop material of the hook and loop fastener tape, wherein in the steamer at the critical value of the control parameter the affinity of the second masking substance to the hook and loop material of the hook and loop fastener tape is smaller than the affinity of the dye to the hook and loop material of the hook and loop fastener tape.

[0036] In the dyeing device, the second masking material bonds faster to the hook-and-loop material of the hook-and-loop fastener tape than the dye bonds to the hook-and-loop material of the hook-and-loop fastener tape. As a result, the second masking material further prevents the dye from bonding to the hook-and-loop fastener tape in the dyeing device. In the steamer, the second masking material is replaced by the dye, allowing the dye to bond to the hook-and-loop fastener tape. The hook-and-loop fastener tape consists primarily of the hook-and-loop material. Sarabid IPF® is used as the second masking material.

[0037] A variant of the process is advantageous in which the hook and loop fastener tape is washed in a first washing device at a temperature of 40°C to 70°C, particularly before step a). This removes dirt residues from the hook and loop fastener tape. In particular, any finishing agents are washed out of the hook and loop fastener tape.

[0038] In a further development of the aforementioned variant of the method, the hook and loop fastener tape, particularly before step a), is washed in a second washing device at a temperature of 70°C to 100°C after the hook and loop fastener tape has been washed in the first washing device. This relieves tension in the hook and loop fastener tape, particularly in the textile fabric of the hook and loop fastener tape. Generally, changes in the dimensions of the hook and loop fastener tape occur at the same time, altering the shape, appearance, and / or functionality of the hook and loop fastener tape. The hook and loop fastener tape becomes particularly supple and flexible.

[0039] In one embodiment of the aforementioned further development, the hook and loop fastener tape is washed, particularly before step a), in a third washing device at a temperature of 20°C to 40°C after the hook and loop fastener tape has been washed in the second washing device. The hook and loop fastener tape undergoes a quenching process, thereby maintaining its supple and flexible state for the subsequent process steps.

[0040] A variant of the method is advantageous in which the control parameter is the temperature of the dye solution, with the critical value of the control parameter in the steamer being in particular in the range from 70°C to 105°C. Preferably, the critical value of the control parameter within the method is in the range from 70°C to 105°C. Temperature is a comparatively easy-to-control process parameter.

[0041] In another variant of the process, the hook-and-loop fastener tape comprises polyamide and is particularly made of polyamide. When polyamide is used, the pH-controlled binding of dye according to the invention is particularly effective.

[0042] In particular, the hook and loop fastener tape comprises polyamide fibers whose structural formula preferably has at least sections of the following form:

[0043] In a preferred variant of the method, the hook and loop fastener tape is continuously passed between two padding rollers to strip off excess dyeing solution after the hook and loop fastener tape has been passed through the dyeing device according to step a) and before the hook and loop fastener tape is passed through the steamer according to step b).

[0044] A gap large enough to allow the hook and loop fastener tape to pass through the gap, removing any dye residue, without damaging or destroying the structures of the hook and loop fastener tape, particularly the loops, mushrooms, and / or hooks. This further improves the even distribution of the dye on the hook and loop fastener tape.

[0045] In a further variant of the process, the dyeing solution comprises a lye, in particular soda, so that the pH value of the dyeing solution in the dyeing device is at least 7.

[0046] In a preferred variant of the process, the dyeing solution contains a defoamer. This prevents the formation of foam during the dyeing of the hook-and-loop fastener tape. Such foam formation can have a detrimental effect on the even distribution of the dye during application of the dye in the dyeing device and / or the bonding of the dye to the hook-and-loop fastener tape in the steamer. Kollasol CDS® is used as a defoamer, in particular.

[0047] A variant of the process is advantageous in which the hook-and-loop fastener tape passes through a water seal upon leaving the steamer. The water seal is, in particular, a water tank filled with water. The water tank is preferably located at an outlet of the steamer, with the hook-and-loop fastener tape passing through the water seal upon leaving the steamer. The transparency of the water in the water seal is an indicator of whether the dye is sufficiently bonded to the hook-and-loop fastener tape.

[0048] In an advantageous variant of the process, the hook and loop fastener tape is subjected to a vacuum extraction system. The vacuum extraction system ensures rapid and even dehumidification and cleaning of the hook and loop fastener tape. The vacuum extraction is particularly effective on both the top and bottom sides of the hook and loop fastener tape.

[0049] A preferred variant of the process involves drying the hook and loop fastener tape with infrared radiation. The infrared radiation ensures rapid and even drying of the hook and loop fastener tape.

[0050] A variant of the process is advantageous in which the thickness of the dye layer on the hook-and-loop fastener tape after passing through the process over a specified length of the hook-and-loop fastener tape does not exceed a specified maximum thickness and / or does not fall below a specified minimum thickness. This ensures a particularly homogeneous distribution of the dye on the hook-and-loop fastener tape.

[0051] A dyeing plant for carrying out the above-mentioned process has the following features: I. A dyeing device with a dyeing solution having a pH of at least 7, wherein the dyeing solution comprises a dye, wherein the dye is in particular an acid dye that binds to the hook and loop fastener tape at a pH of less than 7; II. A damper, wherein the damper is configured to lower the pH of the dyeing solution to below 7 in order to enhance adhesion of the dye to the hook and loop fastener tape. III. A hook and loop fastener tape, wherein the hook and loop fastener tape is passed through the dyeing device and the damper.

[0052] The device allows for uniform coloring of the Velcro tape.

[0053] The method according to the invention optionally also includes a step in which the staining solution is slightly thickened, in particular with Tubivis Star ®< .

[0054] Further advantages of the invention will become apparent from the description and the drawings. Likewise, the above-mentioned and further-described features can be used individually or in combinations according to the invention. The embodiments shown and described are not intended to be exhaustive, but rather are exemplary in nature for describing the invention. Detailed description of the invention and drawing

[0055] Fig. 1 shows a schematic longitudinal section through a first part of a dyeing system; Fig. 2 shows a schematic longitudinal section through a second part of the dyeing system.

[0056] Fig. 1 shows schematically a longitudinal section through a first part of a dyeing plant 10 for a Velcro fastener 12,wherein the hook and loop fastener tape 12 undergoes a process for dyeing the hook and loop fastener tape 12 in the dyeing system 10. The hook and loop fastener tape 12 is continuously guided through the dyeing system 10 during the process.

[0057] In the dyeing system 10, the hook and loop fastener tape 12 is fed from a storage roll 14 from a warehouse 16 moved. Statements about the hook and loop fastener tape 12 in connection with the process for dyeing the hook and loop fastener tape 12 refer in particular to a section of the hook and loop fastener tape 12 that is located on the storage roll 14 at the beginning of the process and is unrolled from the storage roll 14 during the process to undergo the process steps described below. Rolling 18of the goods storage 16 are displaceable relative to one another, particularly in the vertical direction, whereby the goods storage 16 can accommodate a partial strip of the hook and loop fastener tape 12 of different lengths depending on the position of the rollers 18. The goods storage 16 thus serves as a storage and buffer for the hook and loop fastener tape 12. After leaving the goods storage 16, the hook and loop fastener tape 12 is guided by a web edge control 20 which is designed to suitably adjust the alignment of the hook and loop fastener tape 12 for passing through the subsequent stations of the dyeing system 10.

[0058] From the web edge control 20, the hook and loop fastener tape 12 passes through a first washing device 22 a car wash 24.The first washing device 22 is filled with a cleaning solution (indicated by a curved line), which in particular contains water, preferably exclusively water. In the first washing device 22, the hook and loop fastener tape 12 is washed at a temperature in the range of 40°C to 70°C. This removes dirt from the hook and loop fastener tape 12. In particular, the first washing device 22 washes out any finishing agents from the hook and loop fastener tape 12. After passing through the first washing device 22, the hook and loop fastener tape 12 is vacuumed 26 which vacuums the Velcro fastener tape 12 on both sides for the purpose of additional cleaning.

[0059] The Velcro fastener tape 12 then passes through a second washing device 28the washing system 24. The second washing device 28 is filled with a cleaning solution (indicated by a curved line), which in particular contains water, preferably exclusively water. In the second washing device 28, the hook-and-loop fastener tape 12 is hydrofixed at a temperature in the range of 70°C to 100°C. This relieves tension in the hook-and-loop fastener tape 12, making the hook-and-loop fastener tape 12 more flexible and supple.

[0060] The hook and loop fastener tape 12 then passes through another web edge control 20 to adjust its alignment. The hook and loop fastener tape 12 is then passed through a third washing device 30the washing system 24, wherein the hook and loop fastener tape 12 is quenched at a temperature in the range of 20°C to 40°C in order to maintain the hook and loop fastener tape 12 in the flexible state that was achieved in the second washing device 28. The third washing device 30 is filled with a cleaning solution (indicated by a curved line), which in particular comprises water, preferably exclusively water.

[0061] After the washing system 24, the hook and loop fastener tape 12 is passed through another vacuum cleaner 26. In a subsequent step, the hook and loop fastener tape 12 is passed through an infrared dryer 32 The infrared dryer 32 ensures even drying of the hook and loop fastener tape 12.

[0062] In the direction of movement of the Velcro fastener tape 12 behind the infrared dryer 32, the Velcro fastener tape 12 passes through a cooling section 34,to cool the hook and loop fastener tape 12. This prevents undesirably early dyeing of the hook and loop fastener tape 12, especially at a time when the hook and loop fastener tape 12 is in a dyeing device 36 for the first time with a dye 40, which is particularly designed as an acid dye (see below). Subsequently, the alignment of the hook-and-loop fastener tape 12 is adjusted in a further web edge control 20.

[0063] After the web edge control 20, the hook-and-loop fastener tape 12 passes through the dyeing device 36, which is designed here as a dyeing trough. The dyeing device 36 contains a dyeing solution 38, which has a pH of at least 7. The dyeing solution 38 is composed of at least the dye 40 and an acid donor 42composed, wherein the dye 40 is designed to bind to the hook and loop fastener tape 12 at a pH value of less than 7. In particular, the dyeing solution 38 comprises a plurality of dyes 40, wherein each dye 40 serves to dye the hook and loop fastener tape 12 in a respective color.

[0064] The acid dispenser 42 is designed to release acid at a critical value of a control parameter. The control parameter is, in particular, the temperature of the dyeing solution 12. In the dyeing device 36, the dyeing solution 12 has a starting value of the control parameter that is below the critical value of the control parameter. Therefore, the dyeing solution 12 in the dyeing device 36 does not bind to the hook and loop fastener tape 12. This can bring about a uniform distribution of the dyeing solution 38 on the surface of the hook and loop fastener tape 12. In particular, it can be prevented that different dyes 40 bind to the hook and loop fastener tape 12 at different speeds, so that the concentration of the dyes 40 on the hook and loop fastener tape 12 deviates from a desired concentration of the dyes 40, which results in an undesirable overall color of the hook and loop fastener tape 12.The critical value of the control parameter is in particular a temperature value of 100°C for the staining solution 38.

[0065] In addition, the staining solution 38 also contains, in particular, a first masking substance 44 and a second masking material 46. The first masking material 44 binds to the dye 40 at the starting value of the control parameter faster than a Velcro material 48of the hook and loop fastener tape 12 to the dye 40. The second masking material 46 binds to the hook and loop material 48 of the hook and loop fastener tape 12 at the starting value of the control parameter more quickly than the dye 40 binds to the hook and loop material 48 of the hook and loop fastener tape 12. The first and second masking materials 44, 46 prevent initial binding of the dye 40 to the hook and loop fastener tape 12, thereby improving the uniform distribution of the dyeing solution 38 on the surface of the hook and loop fastener tape 12 in the dyeing device 36.

[0066] After the dyeing device 36, the hook and loop fastener tape 12 is passed through padding rollers 50A distance is formed between the padding rollers 50 such that dye 40 is stripped from the surface of the hook and loop fastener tape 12 without damaging the structure of the hook and loop fastener tape 12. Excess dye 40 is thereby removed from the hook and loop fastener tape 12, and the application of dye 40 to the hook and loop fastener tape 12 is further homogenized.

[0067] From the padding rollers 50, the hook and loop fastener tape 12 enters a damper 52,in which water vapor is present, which here is saturated steam. Atmospheric oxygen is completely or almost completely removed from the steamer 52. In the steamer, the value of the control parameter is increased to the critical value. In particular, the hook and loop fastener tape 12 with the applied dye solution 38 is heated to at least 100°C. The acid dispenser 42 releases acid in the steamer 52 when the critical value is reached by the control parameter, in particular when the dye solution 38 on the hook and loop fastener tape 12 is heated to 100°C. The pH value of the dye solution 38 drops below 7. The first masking substance 44 is designed such that the first masking substance 44 in the steamer 52 releases the dye 40 when the control parameter assumes the critical value, in particular when the dye solution 38 in the steamer 52 is heated to 100°C.The second masking material 46 is configured such that the second masking material 46 in the steamer 52 is replaced by the dye 40 on the hook-and-loop material 48 when the control parameter reaches the critical value, particularly when the dye solution 38 in the steamer 52 is heated to 100°C. Lowering the pH of the dye solution 38 and changing the binding behavior of the masking materials 44, 46 in the steamer 52 causes the dye 40 to bind to the hook-and-loop fastener tape 12. The dye 40 binds to the hook-and-loop fastener tape 12 with uniform distribution and composition of the dye 40 on the surface of the hook-and-loop fastener tape 12. The hook-and-loop fastener tape 12 is thus uniformly colored.

[0068] At an exit 54 of the damper 52, through which the Velcro fastener tape 12 is guided out of the damper 52, there is a water lock 56,which is designed here as a water container filled with water (indicated by a curved line). The hook-and-loop fastener tape 12 is guided through the water in the water lock 56. The water in the water lock remains transparent if no dye detaches from the hook-and-loop fastener tape 12 and enters the water. Thus, the transparency of the water in the water lock 56 is an indicator of whether the dye 40 is bonded to the hook-and-loop fastener tape 12 as intended.

[0069] Fig. 2 shows schematically in longitudinal section a second part of the dyeing system 10, which is located in the conveying direction of the hook and loop fastener tape 12 at the Fig. 1 shown first part of the dyeing system 10.

[0070] In the conveying direction of the Velcro fastener tape 12 behind the water lock 56 (cf. Fig. 1 ) the Velcro fastener tape 12 is passed through another vacuum extractor 26.

[0071] The Velcro fastener tape 12 then goes into another washing system 58 with a first washing unit 60, second washing unit 62 and third washing unit 64, which are designed here in the form of open containers to remove unbound dye solution 38 from the hook and loop fastener tape 12. In the washing units 60, 62 and 64 of the further washing system 58 there is a cleaning agent which is Fig. 2 indicated by curved lines within the washing units 60, 62, 64. The cleaning agent comprises, in particular, water, preferably exclusively water. Between the first and second washing units 60, 62, the hook-and-loop fastener tape 12 passes through a further web edge control 20. Between the second and third washing units 62, 64, the hook-and-loop fastener tape 12 is guided through a further web edge control 20 to adjust the alignment of the hook-and-loop fastener tape 12.

[0072] Behind the further washing system, another vacuum cleaner 26 is positioned for cleaning the dyed hook and loop fastener tape 12.

[0073] After the further vacuum extractor 26, the hook and loop fastener tape 12 passes through an ironing system 66 with several, in particular four, electrically heated cylinders arranged in series 68, along which the hook-and-loop fastener tape 12 is guided. This smooths the hook-and-loop fastener tape 12 for subsequent coating processes. Behind the ironing system 66 is another web edge control 20 for adjusting the alignment of the hook-and-loop fastener tape 12.

[0074] In the running direction of the hook and loop fastener tape 12 behind the further web edge control 20, the hook and loop fastener tape 12 is guided by a splash roller 70 The Velcro fastener tape 12 can be efficiently coated by means of the flattening roller 70.

[0075] The Velcro tape is then placed in a dryer 72 in which the Velcro fastener tape 12 is dried for further use.

[0076] The Velcro fastener tape 12 is stored behind the dryer 72 on another storage roll 74 rolled up for further use.

[0077] Taking a summary of all the figures of the drawing, the invention relates to a method for dyeing a hook and loop fastener tape 12, wherein the hook and loop fastener tape 12 continuously passes through a basic or neutral dyeing solution 38 in a dyeing device 36. The dyeing solution 38 adheres to the hook and loop fastener tape 12. The dyeing solution 38 comprises a dye 40 that only binds to the hook and loop fastener tape 12 when the dyeing solution 38 is in an acidic state. After passing through the dyeing device 36, the hook and loop fastener tape 12 with the attached dyeing solution 38 is passed through a steamer 52, causing the dyeing solution 38 to become acidic. The dye 40 adheres to the hook and loop fastener tape 12 to dye the hook and loop fastener tape 12. The invention also relates to a dyeing system 10 for carrying out the method. Reference symbol list

[0078] 10 Dyeing system 12 Hook and loop fastener tape 14 Storage roll 16 Fabric storage 18 Fabric storage rollers 20 Web edge control 22 First washing unit 24 Washing system 26 Vacuum extractor 28 Second washing unit 30 Third washing unit 32 Infrared dryer 34 Cooling section 36 Dyeing device 38 Dyeing solution 40 Dye 42 Acid dispenser 44 First masking material 46 Second masking material 48 Hook and loop material 50 Padding rollers 52 Steamer 54 Steamer outlet 56 Water lock 58 Further washing system 60 First washing unit of the further washing system 62 Second washing unit of the further washing system 64 Third washing unit of the further washing system 66 Ironing system 68 Ironing system cylinder 70 Padding roller 72 Dryer 74 additional storage roll

Claims

1. A method for dyeing a hook and loop fastener tape (12) comprising hooks, mushrooms and / or loops, the method comprising the following successive steps: a) Continuously passing the hook and loop fastener tape (12) through a dyeing device (36) in order to apply a dyeing solution (38) having a pH of at least 7 to the hook and loop fastener tape (12), the dyeing solution (38) comprising a dye (40), the dye (40) being designed in particular as an acid dye which binds to the hook and loop fastener tape (12) at a pH of less than 7; b) Continuously passing the hook and loop fastener tape (12) with the applied dye solution (38) through a steamer (52), wherein the pH value in the steamer (52) is reduced to below 7 in order to increase adhesion of the dye (40) to the hook and loop fastener tape (12).

2. The method according to claim 1, wherein the dyeing solution (38) comprises an acid dispenser (42) configured to release acid at a critical value of a control parameter of the damper (52) in order to lower the pH of the dyeing solution (38) in the damper (52).

3. The method according to claim 2, wherein the control parameter is the temperature of the dyeing solution (38) in the steamer (52), the critical value of the control parameter being in particular in the range from 70°C to 105°C.

4. The method according to claim 2 or 3, wherein the dyeing solution (38) comprises a first masking substance (44) which, in the dyeing device (36), at the starting value of the control parameter, has an affinity to the dye (40) which is greater than the affinity of a hook and loop material (48) of the hook and loop fastener tape (12) to the dye (40), wherein in the damper (52) at the critical value of the control parameter, the affinity of the first masking substance (44) to the dye (40) is less than the affinity of the hook and loop material (48) of the hook and loop fastener tape (12) to the dye (40).

5. Method according to one of the preceding claims, wherein the hook and loop fastener tape (12) is washed in a first washing device (22) at a temperature of 40°C to 70°C, in particular before step a).

6. The method according to claim 5, wherein the hook and loop fastener tape (12), in particular before step a), is washed in a second washing device (28) at a temperature of 70°C to 100°C after the hook and loop fastener tape (12) has been washed in the first washing device (22).

7. The method according to claim 6, wherein the hook and loop fastener tape, in particular before step a), is washed in a third washing device (30) at a temperature of 20°C to 40°C after the hook and loop fastener tape (12) has been washed in the second washing device (28).

8. Method according to one of the preceding claims, wherein the control parameter is the temperature of the dyeing solution (38), wherein the critical value of the control parameter in the steamer (52) is in particular in the range from 70°C to 105°C.

9. Method according to one of the preceding claims, wherein the hook and loop fastener tape (12) comprises polyamide, in particular is formed from polyamide.

10. The method according to any one of the preceding claims, wherein the hook and loop fastener tape (12) is continuously passed between two padding rollers (50) to strip off excess dyeing solution (38) after the hook and loop fastener tape (12) has been passed through the dyeing device (36) according to step a) and before the hook and loop fastener tape (12) is passed through the damper (52) according to step b).

11. Method according to one of the preceding claims, wherein the dyeing solution (38) comprises a lye, in particular soda, so that the pH of the dyeing solution (38) in the dyeing device (36) is at least 7.

12. The method according to any one of the preceding claims, wherein the dyeing solution (38) comprises a defoamer.

13. Method according to one of the preceding claims, wherein the hook and loop fastener tape (12) passes through a water lock (56) when leaving the damper (52).

14. Method according to one of the preceding claims, wherein the hook and loop fastener tape (12) undergoes a vacuum extraction.

15. The method according to any one of the preceding claims, wherein the thickness of the layer of dye (40) on the hook and loop fastener tape (12) after passing through the method over a predetermined length of the hook and loop fastener tape (12) does not exceed a predetermined maximum thickness and / or does not fall below a predetermined minimum thickness.

16. Dyeing system (10) for carrying out a method according to one of the preceding claims, wherein the dyeing system (10) comprises: I. A dyeing device (36) with a dyeing solution (38) having a pH of at least 7, wherein the dyeing solution (38) comprises a dye (40), wherein the dye (40) is in particular designed as an acid dye which binds to the hook and loop fastener tape (12) at a pH of less than 7; II. A damper (52), wherein the damper (52) is designed to lower the pH of the dyeing solution to below 7 in order to increase adhesion of the dye (40) to the hook and loop fastener tape (12). III. A hook and loop fastener tape (12), wherein the hook and loop fastener tape (12) is passed through the dyeing device (36) and the damper (52).

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