EP3044360B1 - Method for chlorine-free anti-felting treatment of wool and wool treated using this method - Google Patents

Description

The invention relates to a process for the chlorine-free felt-free finishing of wool.

Wool is a protein fiber with a complex structure. Due to the growth and function or task of the hair, the fiber core (cortex) is covered by a relatively hydrophobic layer. This outer layer is called the cuticle and consists of scales placed on top of each other like roof tiles. Due to this outer scale structure, a wool hair has a different mechanical friction resistance depending on the direction of the fibers or the direction of the scale structure. The sawtooth-like structure allows for easy movement in one direction, while in the other direction the fibers tend to get caught. This effect leads to a densification of the textile wool structure, particularly when exposed to moisture, temperature and mechanics; one speaks of matting. This process can be used for the targeted compaction of nonwovens, wovens and knitted fabrics into felts/wooled materials/loden.

However, in many uses of woven and knitted fabrics, the process of felting is undesirable because it involves changing dimensions of a fabric and also adversely changes the appearance and feel of the product. Especially when washing, the effects of moisture, surfactants, temperature and mechanics cause strong mechanical compaction of the woolen items. Appropriate measures and pretreatments for wool are therefore described in the literature, which have the task of preventing unwanted felting of wool products during washing and use.

Products that have undergone particularly high-quality treatments are described as machine washable because there is particularly little shrinkage and matting. In order to pretreat a wool product so that it becomes machine washable, various methods have been provided in the literature.

The most important process, the so-called Chlor-Hercosett process, uses a multi-stage treatment of the wool fibers with chlorine, followed by a reductive treatment with sulfite and a deposition of polymeric substances. The effect of these treatments is a "masking" of the scale structure through oxidative erosion as a result of the chlorine treatment, through reductive detachment of products through the sulfite treatment (sulfitolysis) and through the deposition of polymer films. The products treated in this way have excellent shrinkage values even after repeated machine washing. However, the working technology has serious disadvantages that arise from the use of chlorine as a treatment agent. In addition to the complicated application technology, the process is carried out at room temperature, caused by the effect of chlorine Critical wastewater ingredients (AOX, adsorbable organic halogen compounds), which can be reduced through optimization, but cannot be avoided and are always released from the process in high concentrations.

In addition to the use of free chlorine, processes using hypochlorite or other chlorine-releasing compounds such as Na-dichloroisocyanurate (NaDCC) have also been described. However, all of these processes have one disadvantage in common: the formation and release of AOX products.

To solve this problem, the use of chlorine-free oxidizing agents to replace the chlorine compounds has been extensively investigated. The use of mixtures of permanganate and hypochlorite have been described. The sole use of potassium permanganate, peracetic acid, organic peroxides and inorganic peroxides, ozone as oxidizing agents has also been described. The use of plasma treatments or the application of proteolytic enzymes has also been researched and described. All of these processes have technical disadvantages in common, which always lead to an unsatisfactory result in terms of the properties of the treated wool. Therefore, no suitable process has been developed from these processes that would allow wool to be treated to such an extent that machine washability can be achieved.

If treated too intensively, matting can be minimized, but the strength of the wool is then reduced to such an extent that the wool is too damaged and can no longer be processed. The above-mentioned processes therefore currently do not provide a viable alternative to the chlorine treatment processes.

An important group of peroxide-based oxidizing agents that are technically easy to handle are peroxosulfates. These products are safe to handle materials with a high oxidation potential, which appear suitable for oxidative treatment of wool. Accordingly, this class of substances has also been studied more intensively for wool treatment. However, the known processes are not suitable for producing machine-washable wool.

Since there are currently no known technically feasible processes for treating wool with inorganic peroxo compounds, the subject of the present invention is to propose a process for continuous treatment that is suitable for delivering high product quality even when treating wool in technically relevant quantities.

US 2,739,034 A describes a method for reducing the tendency of felting and shrinkage of wool, the document primarily dealing with the problem of shrinkage . Treatment with peroxomonosulfuric acid is shown in the first step, but a surfactant is only used in some examples. However, felt-free finishing cannot take place without surfactant.

According to the prior art, different processes are provided for treating wool with peroxomonosulfate.

In a common embodiment, these processes consist of an oxidative treatment with a solution containing peroxomonosulfate, followed by a reductive treatment. Post-treatment with polymer is also often described. The procedures differ in the way the different procedures are combined and, accordingly, in the results that result from the treatment.

WO 92/00412 A1 describes a process for continuous oxidative felt-free treatment in which a mixture of hydrogen peroxide and potassium peroxomonosulfate are used to treat wool by a squeegee application. After a short reaction time of 1 minute, the wool is immediately treated in a sulfite solution without intermediate rinsing and, after further rinsing, is provided with a polymer coating. However, excessive washing shrinkage is observed.

WO 93/13260 A shows a discontinuous treatment process for wool, as the sample pieces are always placed in treatment solutions. Apart from the impregnation step in application example 3, a stepwise treatment is provided for the remaining steps.

EP 0 356 950 describes a discontinuous process for the treatment of wool knitted fabrics.

The WO 99/10588 A1 discloses a method for treating wool with peroxomonosulfate solutions, in which the first step is pre-wetting with a surfactant solution and then the oxidation treatment, the reductive treatment and the deposition of a polymer take place. The procedure disclosed in this document is fully continuous and therefore offers no possibility of changing the short reaction time, which is shorter than 1 minute, after the oxidizing agent treatment. A combination of wetting agent treatment and oxidizing agent treatment is not recommended as this leads to poor product quality (Application Example 1, Experiments 3, 4 and 5). The process has not found its way into technical reality because the process stability and reproducibility must be assessed critically. Due to the short reaction time, the use of pre-wetted goods for the oxidant treatment and the lack of intermediate rinsing between the treatment compartments due to the size of the machine, control of the treatment conditions and thus the result is critical.

According to the state of the art, a wide variety of processes have been proposed and tested that are intended to enable chlorine-free treatment of wool to produce machine-washable products. An improvement in wool properties compared to untreated wool has been achieved, but the processes are more complicated, in many cases require the use of additional chemicals and are difficult to control in terms of the quality standards achieved. Accordingly, the processes could not be technically used to produce products at the quality level of the classic chlorine-Hercosett treatment.

It is now the object of the present invention to provide a procedure that is able to produce machine-washable wool in a chlorine-free process in such a way that the above-mentioned disadvantages are avoided.

1. a) Aufbringen einer Lösung auf die Wolle, wobei die Lösung ein Oxidationsmittel basierend auf Peroxomonoschwefelsäure und ein Tensid aufweist,
   • wobei die Menge an Tensid 0.3 bis 5 % (w/w) bezogen auf die Masse an Wolle beträgt,
   • wobei die Menge an Peroxomonoschwefelsäure zwischen 0.5 und 25 % (w/w) bezogen auf die Masse an Wolle beträgt
2. b) Einwirkenlassen der Lösung auf die Wolle, um den Oxidationsvorgang abzuschließen,
3. c) Auswaschen der Reaktionsfolgeprodukte aus der Wolle,
4. d) Behandlung der Wolle mit einem Reduktionsmittel, wobei das Reduktionsmittel Sulfit ist und die Menge an Sulfit zwischen 5 und 15 % (w/w) bezogen auf die Masse an Wolle beträgt, wobei die Verweilzeit zwischen 10
   und 60 s, die Temperatur zwischen 20 und 55 °C konstant gehalten wird und der pH zwischen 8 und 11 konstant gehalten wirdbeträgt, und
5. e) Nachwäsche der Wolle,

wobei die Schritte kontinuierlich ablaufen. Bei der Lösung handelt es sich bevorzugt um eine wässrige Lösung.This task is solved by a process for the chlorine-free felt-free finishing of wool, characterized by the following steps

1. a) applying a solution to the wool, the solution comprising an oxidizing agent based on peroxomonosulfuric acid and a surfactant,
   • where the amount of surfactant is 0.3 to 5% (w/w) based on the mass of wool,
   • where the amount of peroxomonosulfuric acid is between 0.5 and 25% (w/w) based on the mass of wool
2. b) allowing the solution to act on the wool to complete the oxidation process,
3. c) washing out the reaction products from the wool,
4. d) treating the wool with a reducing agent, the reducing agent being sulfite and the amount of sulfite being between 5 and 15% (w/w) based on the mass of wool, the residence time being between 10
   and 60 s, the temperature is kept constant between 20 and 55 ° C and the pH is kept constant between 8 and 11, and
5. e) after-washing the wool,

where the steps occur continuously. The solution is preferably an aqueous solution.

The oxidizing agent includes peroxomonosulfuric acid (H ₂ SO ₅ ), salts or combinations thereof. Suitable salts of peroxomonosulfuric acid are, for example, KHSOs (2KHSO ₅ .KHSO ₄ .K2SO ₄ ).

In one embodiment variant, it has been shown that the amount of peroxomonosulfuric acid, preferably between 1% and 20% (w/w), particularly preferably not more than 15% (w/w), based on the mass of wool. The concentrations in the batch formulation can be converted according to the settings of the application unit and the inorganic peroxomonosulfate compound used.

The chemicals required for step a) are applied in dissolved form, with aqueous solutions being used in a preferred form. It has advantages proven when the applied solution has a pH value <7. The pH value is preferably between 1 and 4, particularly preferably the pH value is below 3.5 in the solution. By dissolving the peroxomonosulfuric acid compounds, the pH of the solution decreases. The pH value can be adjusted as required by adding appropriate acid or alkali.

It has proven to be advantageous for the process if the temperature of the solution in step a) is up to 60 ° C, preferably between 15 ° C and 45 ° C.

In one embodiment variant, the reaction time of step b) can be over 1.5 minutes, preferably between 5 and 10 minutes.

The wool to be treated should be able to be processed using a continuously operating system, e.g. yarn, fleece, combing, woven fabric, embroidery, combing or combinations thereof. In a preferred form, combing is treated. If appropriate guide devices are used, treatment in open form (flake) is also possible.

The wool can be pure wool or a wool blend.

The surfactant preferably has a negative overall charge or a neutral charge on the surface-active part of the molecule. The surfactant is particularly preferably selected from the group of nonionic surfactants.

The wetting agent required for step a) can come from the group of anionic or nonionic surfactants; nonionic products are preferred, alkylene oxide condensation products are particularly preferred.

In one embodiment variant, the amount of surfactant can preferably be between 0.5% and 4% (w/w), based on the mass of wool.

The reaction time of steps c) and d) is longer than 10 s, preferably 30 s to 60 s.

In one embodiment variant it is provided that step d) takes place in an aqueous solution.

The amount of Sulphite is between 5 and 15% (w/w).

A post-treatment of the wool can also be provided. This takes place either after or at the same time as step e).

For the aftertreatment, treatment with a substance that reduces surface friction, in particular plasticizer and/or polymer, can be provided. The amount of plasticizer or polymer is preferably sufficient to result in a deposit of more than 0.1% (w/w) product based on the mass of the wool.

In a preferred embodiment, polymers from the group of siloxanes are used.

In one aspect, the invention relates to wool and wool products produced or producible by the process.

Although parts of steps a) to e) were proposed according to the prior art, the novel combination led to unexpectedly good results, particularly with regard to process stability and properties of the treated wool.

In the process according to the invention, continuous process techniques are combined with semi-continuous work techniques. This makes it possible to combine the relatively short treatment times for a), c), d) which are between 10 s and 1 minute and e) with a semi-continuous treatment b) which can be over 1.5 minutes.

In order to apply the oxidizing agent solution to the wool, a foulard is usually used, which is able to apply between 70% and 150% liquor in a defined manner. In a preferred form, the device is adjusted so that the constant application amounts are between 75% and 125% of the own weight the wool is transferred to the reaction section b). In a particularly preferred form, the application is between 90% and 110%. Fleet application by spraying, dripping or other known liquor application techniques is also possible.

The speed of the continuous system results from the generally known technical process parameters of the design, for example the length of the dwell section in a treatment compartment, and is between 5 - 12 m/min in conventional technical designs, which corresponds to a treatment time per machine compartment of approximately 10 s to 30 s.

For step b), allowing the solution to act on the wool in order to complete the oxidation process, the wool impregnated with oxidizing agent solution is placed on a suitable shelf in such a way that a uniform temperature setting is possible and no sagging of the treatment solution occurs. For this purpose, common material storage techniques can be used, such as roller beds, screen belt deposits, slides, and a guided dwell section is also possible. In a preferred embodiment, the temperature in the tray is controlled. The temperature is kept below 60 ° C; in a particularly preferred procedure, the temperature is kept below 45 ° C. The required reaction time for step b) depends on the temperature and chemicals or the recipe used in step a). A reaction time of over 1.5 minutes has proven to be effective and in a preferred embodiment of the process the duration of step b) is kept between 2 and 10 minutes. The reaction time can be estimated by testing the reaction speed of a recipe in step b) and analytically tracking the progress of the reaction.

In step c), the reaction products from the oxidizing agent treatment are washed out by rinsing and largely removed. This step is preferably carried out by rinsing with water, the treatment temperature is between 10 ° C and 65 ° C, in a preferred embodiment the temperature of the washing water is 15 - 25 ° C. The treatment time is in the range of the usual duration for continuous treatment processes, which is between 10 s and 30 s. This step improves the process stability in a particularly advantageous manner.

In stage d) the rinsed wool is treated with a reducing agent. This can come from the group of sulfites, but other reducing substances can also be tested for their suitability through preliminary tests. The pH value and the temperature of the treatment bath depend on the available residence time for section d). The residence time is between 10 and 60 s, with the temperature being kept at a constant value in the range of 20 - 55 °C and the pH value in the range between 8 and 11 by dosing alkaline solutions or buffering substances, e.g. soda or sodium bicarbonate is kept constant.

In treatment stage e), the reductively treated wool is washed and treated. Intensive rinsing with water removes reaction chemicals and their products from the wool. Suitable substances are then applied which act as supports to reduce surface friction. There are one for this A variety of substances can be used, with suitable chemicals being able to be selected from the class of polymeric substances and also from plasticizing substances.

The selection of products and the amount of polymeric/softening substance depends on the fineness of the wool fiber to be treated and can be determined through preliminary tests. The temperature of the treatment solution can be between 15 ° C and 80 ° C, with the solution being applied at room temperature in a particularly preferred embodiment.

Polymers can be selected from the following classes: polymers with primary, secondary and/or tertiary amino functions, such as homo- or co-polymers of acrylamide and/or methacrylamides with, for example, styrene, acrylic acid or acrylic acid esters; polyurethanes; polyalkyleneimines; polyvinylamines; polyamide amines; aliphatic, cycloaliphatic and aromatic polyisocyanates; polyethylene; polyamide-epichlorihydrin resins; Polyacrylates, polysiloxanes. In a preferred form, modified polysiloxanes are used; amino-functional polysiloxanes are particularly suitable.

A plasticizer can, for example, come from the group of quaternary organic ammonium salts; other suitable products can also be easily identified from the group of known textile softeners through preliminary tests.

If necessary, intermediate drying can also take place after washing steps.

Since the treatment leads to changes in the wool structure, especially in the cuticle, detection and identification of the treatment is possible using appropriate analytical methods. In addition to the change in the molecular structure, which can be detected by infrared spectroscopy, microscopic methods such as electron microscopic examinations with EDX analysis (energy dispersive X-ray spectroscopy), AFM (atomic force microscopy), or light microscopy are suitable for detecting the different treatments. In particular, transmitted light microscopy of fibers swollen in water and microscopy of fibers stained with methylene blue are well suited to distinguishing between treatments.

Changes in fiber accessibility as a result of different treatments have also been described in the literature ( Journal of the Textile Institute, 103/1, (2012) 55-63 ).

Application examples

The percentages in the application examples always refer to the mass of chemicals used based on the mass of wool treated.

Example 1:

A wool comb with an average wool fineness of 20.5 µm is impregnated with a solution in the foulard. With a liquor intake of 100% of the material mass, the quantity of potassium hydrogen peroxomonosulfate is 7.6% of the wool mass and the quantity of wetting agent is 1.5% of the wool mass. The solution is applied at 40 °C, then the goods are stored at approx. 35 °C for at least 1.5 minutes.

After a rinsing step with water, the treatment is carried out in a sulfite solution (150 g/l sodium sulfite). The consumption of sodium sulfite is around 8% of the wool mass. The treatment takes place at 35 °C for 30 s, then rinsed with water.

The final application of 4% of the wool weight of a silicone-based polymer (40 g/l) is carried out by wet-on-wet application, followed by a drying step. The shrinkage of the goods in washing tests is less than 1%.

Example 2:

A wool comb with an average wool fineness of 21.5 µm is impregnated with a solution in the foulard. With a liquor intake of 100% of the material mass, the quantity of potassium hydrogen peroxomonosulfate is 5.4% of the wool mass and the quantity of wetting agent is 1.5% of the wool mass. The solution is applied at 40 °C, then the goods are stored at approx. 35 °C for at least 1.5 minutes. After a rinsing step with water, the treatment is carried out in a sulfite solution (150 g/l sodium sulfite). The consumption of sodium sulfite is around 8% of the wool mass. The treatment takes place at 35 °C for 30 s, then rinsed with water. The final application of 3% of the wool weight of a silicone-based polymer (30 g/l) is carried out by wet-on-wet application, followed by a drying step. The shrinkage of the goods in washing tests is less than 7.5%.

Example 3:

A wool comb with an average wool fineness of 26.5 µm is impregnated with a solution in the foulard. With a liquor absorption of 100% of the fabric mass, the quantity of potassium peroxomonosulfate is 7% of the wool mass and the quantity of wetting agent is 1.5% of the wool mass. The solution is applied at 40 °C, then the goods are stored at approx. 35 °C for at least 1.5 minutes. After a rinsing step with water, the treatment is carried out in a sulfite solution (150 g/l sodium sulfite). The consumption of sulfite solution is around 8% of the wool weight. The treatment is carried out at 35 °C for 30 s, then rinsed with water.

The final application of 2% of a silicone-based polymer is carried out by wet-on-wet application, followed by a drying step. The shrinkage of the goods in washing tests is 14.2%.

Claims (14)

1. A method for the chlorine-free anti-felting treatment of wool, characterized by the steps of

   a) applying a solution onto the wool, wherein the solution comprises an oxidizing agent based on peroxomono sulphuric acid and a tenside,

   wherein the amount of tenside is 0.3 and 5 % by weight based on the mass of wool,

   wherein the amount of peroxomono sulphuric acid is between 0.5 and 25 % by weight based on the mass of wool,

   b) exposing the wool to the solution in order to complete the oxidation process,

   c) washing out the secondary reaction products from the wool,

   d) treating the wool using a reduction agent, wherein the reduction agent is sulphite and the amount of sulphite is between 5 and 15 % by weight based on the mass of the wool, wherein the residence time is between 10 and 60 s, the temperature is kept constant between 20 and 55 °C and the pH is kept constant between 8 and 11 and

   e) post-washing,

   wherein the steps are carried out continuously.
2. A method according to claim 1, characterized in that the wool is present as pure wool or as a wool blend or that the wool is present as loose fibres, sliver, yarn, fabric, crocheted fabrics, fleece or combinations thereof.
3. A method according to claim 1 or claim 2, characterized in that the oxidizing agent comprises an inorganic monoperoxo compounds, in particular a peroxomono sulphuric acid (H₂SO₅), salts thereof or combinations thereof.
4. A method according to any of claims 1 to 3, characterized in that the tenside has a negative overall charge or a neutral charge of the surface active molecule part, preferably the tenside is selected from the group of the non-ionic tensides.
5. A method according to any of claims 1 to 4, characterized in that the amount of tenside is between 0.5 % by weight and 4 % by weight based on the mass of wool.
6. A method according to any of claims 1 to 5, characterized in that the amount of peroxomono sulphuric acid is between 1 and 20% by weight, especially preferably not more than 15 % by weight, based on the mass of wool.
7. A method according to any of claims 1 to 6, characterized in that the solution applied has a pH of <7.
8. A method according to any of claims 1 to 7, characterized in that the temperature of the solution in step a) is up to 60 °C, preferably between 15 °C and 45 °C.
9. A method according to any of claims 1 to 8, characterized in that the reaction period of step b) is more than 1.5 min, preferably between 5 and 10 min.
10. A method according to any of claims 1 to 9, characterized in that the reaction period of the steps c) and d) is more than 10 s, preferably 30 s to 60 s.
11. A method according to any of claims 1 to 10, characterized in that step d) is carried out in an aqueous solution.
12. A method according to any of claims 1 to 11, characterized by a post-treatment of the wool after or concurrently with step e).
13. A method according to any of claims 1 to 12, characterized in that the post-treatment is carried out using a softening agent and/or a polymer.
14. Felt-free wool, obtainable according to any of claims 1 to 13.