Technical Field

The invention relates to a method for obtaining the smart fabrics based on the textile technology and science for the textile industry.

In particular, the invention comprises a method that improves the comfort and end-use performance under the dynamic conditions in the different kinds of fabrics, including sports textiles, fabrics used as inner layers of the protective clothing, and the application of the temperature-moisture responsive nanocomposite structures to the fabrics. At this stage, it was intended to optimize the shape memory and fabric hand performances, and the new methods were developed for testing the shape memory performances.

State of the Art

With the developments in the chemistry and material technologies and the effect of the media, the expectations for providing the comfort under all conditions, the formation of the trends including the personalized thermal management, and ease of use are increasing day by day.

The professional or amateur sportsmen and workers in a working line in which the protective clothing is used demand that they feel comfortable and not experience a decrease in performance in case of high body temperature and/or sweating. The decrease in performance due to the inability to provide the thermal comfort of the person in the relevant conditions, environments and activities is one of the most fundamental problems encountered in the state of the art. Considering the subjects studied for this purpose, the structures used for the thermal comfort are the air and liquid-based cooling/heating structures in the electrotextiles group and the systems that buffer the body temperature according to the ambient conditions with the phase change material (PCM) applications. In the electrotextile-based structures, the clothing into which the system (steam compression systems, pumps, etc.) is integrated has the problems in terms of wearability/washability due to the rigidity as well as the energy requirement and the weight of the batteries used. In PCM applications that use the latent heat of the material, there are the problems such as short activity times and the periods required for the storage, and insufficient fastness in the fabric applications. The high cost of these applications also limits their applicability to the commercial products.

In the textile applications of the shape memory polymers, the temperature responsive shape memory polymers and particularly the shape memory polyurethanes draw attention with their transition temperature (T _g ) varying in a wide temperature range depending on the type and ratio of the hard and soft segments in their structures, ease in formability, and a wide range of raw material and additive potentials (Qakmak, 2013; Zhao et al., 2015). The methods used and high costs appear as the disadvantages in existing techniques in terms of applicability.

In the researches, the shape memory polyurethanes (SMPU) can be used in different forms such as film, fiber, fabric coating/finishing process for the production of the smart textile materials. The commercial applications of the temperature responsive shape memory polymers include Diaplex®, the water-repellent, breathable membrane by Mitsubishi for the aerospace products, packaging materials, medical products, rigid storage materials and toy industry, as well as for the textile products, and the products such as MemBrain® by Marmot and Dermizax® by Toray. The reaction temperature of Diaplex, which has the widest product range among the specified products, can be adjusted according to the end-use needs, and in addition to the products in many different sectors, the material is also available on the market as the products such as a water-repellent outer layer of clothing in the textile sector, tapes and wraps, breathable shoes, baby diapers, etc. (SMP, 2019). The t-shirt named "Sphere React Shirt" by Nike is also a shape memory polymer-based product, in which the sweat formed is transferred through the openings in the fabric structure with the shape memory polymer acting sensitively to moisture.

With the invention, it is intended to develop the properties of the fabrics in the textile industry and the knitted and woven fabric industry, and as a sub-group, the sports and leisure clothing fabrics, which are one of the areas with the most increasing market shares today. The products included in the state of the art and listed below only belong to the water-repellent breathable coatings that are responsive to temperature or moisture. Since it is simultaneously responsive to both temperature and water/humidity, the product described in the invention is completely different from these products which are detailed below.

-Diaplex® by Mitsubishi (temperature responsive),

-MemBrain® by Marmot (temperature responsive),

-Dermizax® by Toray (temperature responsive), -T-shirt named "Sphere React Shirt" by Nike (moisture responsive).

When the previous studies, even if not directly related to the invention, were examined, it was seen that only temperature responsive breathability on cotton and polyester; crease/wrinkle recovery and retention functions of the cotton and woolen fabrics were carried out. It has been determined that the shape memory polymers are applied to the cotton and woolen woven fabrics for providing temperature responsiveness, wrinkle recovery, and water repellency by temperature responsive smart coatings and finishing processes as the closest studies to the present invention.

No study that fully overlaps with the present invention has been found in the field of the functional and smart materials produced by the textile industry for the improvement of the comfort and in the international literature. No patent application has been encountered within the scope of the present invention. However, there are only temperature or moisture responsive water-repellent breathable structures at the level of scientific studies or patent, and only the studies in which only temperature or moisture responsive structures are applied as a finishing process and crease/wrinkle recovery functions are also obtained. These patent studies are summarized below.

In the art described in the patent application no. CN100395397C, the high washing resistance, adhesion strength, crease and wrinkle resistance, hand and shape memory properties were obtained in the fabrics with the only temperature responsive shape memory finishing process (5-500 nm) applied to fabrics.

In the art described in the patent application no. CN1648143, only temperature responsive shape memory polyurethane finishing process (polymer concentration of 15%-30%) and the subsequent plasma treatment provided the anti-wrinkle and shape stability properties in the fabrics.

In the art described in the patent application no. CN1648143A, the cotton fabrics of (42/43 30s *

30s, 68 * 68) are subjected to the finishing process with water-based shape memory polyurethane (6% of solid content/concentration, 2% of softener, 2% of fixator, dipping 2 times and squeezing 2 times, drying for 3 minutes at 850 , curing for 2 minutes at 1500 and coating (40% of concentration, dipping in 2% of Tai-Ace S 150 flocculating agent aqueous solution while the coating is not dry, dipping for 2 minutes at 400, drying at 80°C, soaking in 600 water for 5-30 minutes for film formation of 0.5 mm). It has been determined that the temperature responsive dynamic wrinkle recovery and crease retention performances in the fabrics are obtained by the applied shape memory polyurethane finishing process. In the art described in the patent application no. CN1818198, the woolen fabric was subjected to only temperature responsive SMPU-based shape memory finishing process, and while the pilling resistance, tactile, flexibility, and strength properties in the fabric are preserved, the properties such as dimensional stability with the shape memory effect, flat appearance, crease retention, bagging recovery during wearing or after washing were detected. The finishing process with SMPU emulsion reduced the felting in the woolen fabrics, thus obtaining a higher dimensional stability value compared to the raw fabric. In addition, the texture of the processed woolen fabric remains the same even after washing 25 times, while the untreated fabric becomes felted after washing 5 times.

In the art described in the patent application no. CN101709197A, the fabrics of different properties were subjected to the temperature responsive hydrophilic crystal type polyurethane coating/finishing process, and it has been determined that the coated fabrics exhibit the temperature responsive water vapor permeability function in the transition temperature range of 17.0-28.0 °C. 100% cotton woven fabric was subjected to the fluorine and oil applications by the steps of coating, drying between steps and curing. 65/35% cotton/polyester fabric was subjected to the same process as a finishing process under the different drying and curing conditions. It is stated that with this process, an increase of approximately five times is observed between the water vapor permeability values at 10°C and 30°C.

In the art described in the patent application no. CN102633976B, the temperature sensitive waterbased polyurethane coating process (80 t00 pm) was performed to provide smart breathability and water repellency. The transition temperature is adjusted to 21°C -34°C based on the raw material content used, and the permeability with temperature varied between 2644-4025 gm^d ¹ , and the water repellency varied between 10.3-29.4 kPa.

In the art described in the patent application no. CN104017164A, the applied shape memory polyurethane was synthesized with a transition temperature of 22-23°C and applied as a coating process (80 t00 pm). The temperature sensitive permeability (3612 gm ² 24 hours - 3953 gm ² 24 hours), water repellency (17.8kPa-31.8kPa) and 19.5%-31.5% of oxygen permeability were obtained. It has been stated that the multifunctional environmentally friendly temperature sensitive fabric coating process, which is synthesized by choosing the different raw materials, rates and reaction conditions, does not release halogen and formaldehyde and provides flame retardancy.

The present studies in the state of the art, as quoted above, have focused on the studies on providing only temperature or only water/humidity repellency to the different types of textile products. Since a fabric that is resistant to temperature and also to water/humidity is not included in the state of the art and the solutions offered are insufficient on the subject, the innovation is required for the method for applying a temperature-water responsive shape memory nanocomposite material to a fabric, which is the subject of the invention. Thanks to the invention, unlike the previous studies and products, the shape memory polyurethane-cellulose nanocrystallite (SMPU-NC) nanocomposite structures simultaneously responsive to both temperature and water/humidity are applied to the sports and protective clothing fabrics, which are produced from different kinds of fibers, in contact with the body and need to absorb body sweat, to maintain the comfort under the conditions where the body temperature increases and/or a feeling of wetness occurs in case of sweating. An end-use fabric, that is not water-repellent but absorbs liquid, is obtained by the method of the invention. Also, unlike the breathable coating applications in the state of the art, the current problems were solved by applying the nanocomposite polymer in the form of the finishing process at a concentration that will increase the bending rigidity of the fabric hand components, within the acceptable limits in this product group where the fabric hand is more important.

Summary of the Invention

The present invention relates to a method for applying a temperature-moisture responsive shape memory nanocomposite material to a fabric, which meets the above-mentioned requirements, eliminates all disadvantages and brings some additional advantages.

The invention relates to the improvement of the properties of the fabrics in the textile industry and the knitted and woven fabric industry, and as a sub-group, the sports and leisure clothing fabrics and protective clothing fabrics, which are one of the areas with the most increasing market shares today.

Thanks to the production of the fabrics responsive to both temperature and water/humidity simultaneously, the object of the invention is primarily to provide comfort with the dynamic porosity function under the conditions where the sweating can occur at low body/ambient temperatures as well as in the cases where the body temperature increases.

By applying the shape memory polyurethane and cellulose nanocrystallite based temperaturemoisture responsive nanocomposite to the knitted and woven fabrics as a finishing treatment, it is ensured that the structure has a smart breathability due to the dynamic porosity and a liquidabsorbing structure with a smart absorption capacity. The fabric obtained by the method of the invention is prevented from wrinkling and bagging due to the temperature and/or moisture, and the crease retention is provided when necessary. These functions also take place during washing and drying procedures, eliminating the need for ironing and providing energy savings. In addition, the dimensional stability and non-felting properties of the fabric obtained are improved.

The invention provides the method for applying the temperature-moisture responsive shape memory polymer nanocomposite in the form of a finishing process. The invention provides the determination of the optimum parameters of the pad-dry-cure steps based on the physical properties of different raw materials and fabrics, and this is one of the innovative aspects of the invention.

The smart breathability and smart absorption capacity of the structure due to the dynamic porosity, as well as wrinkle resistance, crease retention, bagging, dimensional stability and anti-felting properties based on the raw material are standardized by applying the following characterization and performance tests to the fabric obtained by the method of the invention.

• Chemical and morphological analyzes (SEM-EDX, FT-IR, DSC)

• Physical and mechanical and fastness tests (tests for weight, thickness, bursting strength, washing fastness)

• Determination of the air and water vapor permeability and liquid absorption and transfer properties under the dynamic conditions

• Determination of the wrinkle recovery, crease retention and bagging recovery properties under the dynamic conditions

• Determination of the dimensional stability and anti-felting properties under the dynamic conditions

The smart breathability function is determined by the air and water vapor permeability tests performed in the environments with different temperatures and relative humidity values. On the other hand, the smart liquid absorption performances are firstly determined in the literature by the absorption time, capacity and transfer tests performed in water at the different temperatures. The modifications to the tests described are another innovative aspect of the patent. The wrinkle recovery, crease retention and bagging recovery properties required according to the raw materials of the fabrics are determined by testing the recovery rates of the deformed fabrics in the different ambient temperatures and relative humidity, and in water environments at different temperatures. The dimensional stability and anti-felting properties (wool) are determined on the fabrics treated within the scope of the current standards. Among physical-mechanical properties (weight, thickness, bending rigidity, strength), the nanocomposite polymer loading ratios are used, which do not increase above the determined limit in bending rigidity, as the fabric hand component. This also differentiates the invention from the studies in which the fabric hand is not primarily taken into account in the market and literature.

The smart functions specified in the invention include temperature and/or moisture responsive smart permeability (air and water vapor) under the dynamic conditions, liquid absorption, wrinkle recovery, crease retention, bagging recovery, dimensional stability, anti-felting properties. Said functions are realized by the application of the shape memory polyurethane-cellulose nanocrystallite. The method described in the invention provides the specified temperature and moisture responsive properties by applying the nanocomposite solution to the knitted and woven fabrics as a finishing process by the steps of pad-dry-cure process in accordance with the physical properties of the raw materials and fabrics.

The method of the invention differs from the state of the art in that it is economical and practical in terms of cost and applicability.

The structural and characteristic features and all advantages of the invention will be understood more clearly thanks to the figures given below and the detailed description written with reference to these figures. Therefore, the evaluation should also be made considering these figures and detailed description.

Detailed Description of the Invention

In this detailed description, the preferred embodiments of the method for applying a temperaturemoisture responsive shape memory nanocomposite material to a fabric are described only for a better understanding of the subject matter and without any limiting effect.

Method according to the invention, which provides the temperature - moisture responsive smart permeability (air and water vapor), liquid absorption, wrinkle recovery, crease retention, bagging recovery, dimensional stability, anti-felting properties under the dynamic conditions by applying the temperature- moisture responsive nanocomposite structures to the fabrics, comprises the steps of obtaining (a) a shape memory polymer solution comprising the steps of adding (a.l) a solvent and a temperature responsive shape memory thermoplastic polyurethane, mixing (a.2) by means of a mechanical mixer operating at 60°C at a speed range of 400- 500 rpm for 6 hours, and leaving (a.3) to stand to remove air bubbles from the resulting solution for 12 hours; obtaining (b) a cellulose nanocrystallite solution comprising the steps of obtaining (b.l) a cellulose nanocrystallite by the sulfuric acid hydrolysis of the cellulose, adding (b.2) a cellulose nanocrystallite, which is a nanofilling material, and a solvent, modifying (b.3) with a non-ionic surfactant at a ratio of 1:2 by weight to provide a homogeneous and stable distribution of the cellulose nanocrystallites in the solvent at a concentration of 0.5% by weight, and mixing (b.4) with an ultrasonic homogenizer at 40-Watt, 40% amplitude and 3-second on/off cycle for 1 hour; forming (c) the nanocomposite polymer solution comprising the steps of mixing (c.l) the shape memory polymer solution with the cellulose nanocrystallite solution, and mixing (c.2) by means of an ultrasonic homogenizer in an ice bath for 1 hour; and finishing process (d) comprising the steps of impregnating (d.l) comprising applying the solution to the fabric until the polymer remaining in the fabric is 5-7% in the final state, drying (d.2) in 10-15 minutes at a temperature of 70 to 90°C, and curing (d.3) in 5 minutes at a temperature of 90 to 120°C.

The method according to the invention comprises the test applications (e) for optimizing the shape memory and fabric hand performances in the step of finishing process (d) in which the temperaturemoisture responsive nanocomposite structures are applied to the fabrics, such as

• air permeability test (e.l) at different fabric temperatures;

• absorption capacity test (e.2) with the water at different temperatures;

• water vapor permeability test (e.3) at different ambient temperatures and at different ambient relative humidity values at the same temperature; • determining (e.4) the increase in bending rigidity of the processed fabric compared to the raw fabric;

• wrinkle recovery and crease retention performance test (e.5) of the fabric treated with water at different temperatures compared to the raw fabric;

• bagging recovery performance test (e.6) of the processed fabric compared to the raw fabric at different temperatures, wherein the optimum value ranges are determined.

In the process of applying the shape memory polyurethane and cellulose nanocrystallite-based temperature-moisture responsive nanocomposite to the cellulosic knitted and woven fabrics suitable for the sports/protective clothing as a finishing process, the nanocomposite solutions with the homogeneous particle distribution are primarily prepared.

The shape memory polymer solution comprises the temperature responsive shape memory thermoplastic polyurethane and solvent and is a homogeneous solution.

Within this scope, for obtaining (a) the shape memory polymer solution, the temperature responsive shape memory thermoplastic polyurethane polymer (M _n =24473; M _w =116483) is primarily preferred as the matrix material.

Said polymer has a shape change temperature (glass transition temperature-T _g ) suitable for the body temperature with 32.32°C according to the DSC analysis data. The polymer consisting of the soft and hard segments acts as a temperature transition point in the nanocomposite structure, providing the temperature responsive shape memory performance.

The step of obtaining (a) a shape memory polymer solution comprises the steps of mixing (a.2) shape memory polyurethane and N,N-Dimethylformamide as a solvent to provide 5%-20% by weight of the shape memory polyurethane by means of a mechanical mixer operating at 60°C at a speed range of 400-500 rpm for 6 hours, to be homogeneous and leaving (a.3) to stand to remove air bubbles from the resulting solution for 12 hours.

The cellulose nanocrystallite solution comprises the cellulose nanocrystallite and a homogeneous solution is obtained by using the non-ionic surfactant and solvent. In the production of the nanocomposite finishing materials, the surface of the nanoparticles is modified with a non-ionic surfactant that does not adversely affect the hydrophilic character to provide the homogeneous distribution of the hydrophilic cellulose nanocrystallites in the hydrophobic polyurethane matrix.

The cellulose nanocrystallite which is added to the polymer matrix as a nanofilling material which is a moisture responsive key transition point of the structure is obtained by the sulfuric acid hydrolysis of the cellulose (b.l) and has a diameter of 10-20 nm (TEM analysis results) and a crystallinity value of 98.98% (XRD analysis results).

The use of N,N-Dimethylformamide is preferred as a solvent in both the cellulose nanocrystallite solution and the shape memory polyurethane solution.

In the preliminary trials (the application of 5%, 10%, 15%, and 20% by weight of the shape memory polyurethane polymer), the optimum temperature responsive functional properties as well as the fabric hand values for the fabrics are obtained at a polymer concentration of 10% by weight.

The step of obtaining (b) a cellulose nanocrystallite solution comprises the steps of modifying (b.3) the nanocrystallite surfaces with the addition of a non-ionic surfactant, preferably polyethylene sorbitol ester (Tween®80), at a ratio of 1:2 (nanoparticle: surfactant) by weight to provide a homogeneous and stable distribution of the cellulose nanocrystallites in N, N-Dimethylformamide (solvent) at a concentration of 0.5% by weight, and mixing (b.4) with an ultrasonic homogenizer at 40 Watt, 40% amplitude and 3-second on/off cycle for 1 hour.

Different amounts of the cellulose nanocrystallite solution can be added to the polyurethane solution prepared in the step of forming (c) the nanocomposite polymer solution. The step of forming (c) the nanocomposite polymer solution comprise the step of mixing (c.2) by means of an ultrasonic homogenizer in an ice bath for 1 hour.

The step of forming (c) the nanocomposite polymer solution comprises the step of mixing (c.l)

• the shape memory polymer solution containing 10% by weight of the shape memory polyurethane

• with the cellulose nanocrystallite solution containing 5% - 20% by weight of the cellulose nanocrystallite based on the polymer weight.

The different amounts of the cellulose nanocrystallite solution were added to the polyurethane solution in order to obtain 5% - 20% of the cellulose nanocrystallite-added shape memory polyurethane solution at different weight ratios compared to the polymer concentration according to the solution mixing method, and the resulting solutions were mixed with an ultrasonic homogenizer for 1 hour in an ice bath to prevent overheating.

The nanocomposite solutions obtained in the final state consisted of 10% by weight of the shape memory polyurethane and 5%, 10% and 20% by weight of the cellulose nanocrystallite concentrations, based on the polymer weight.

The nanocomposite polymer solution, which is prepared by providing the homogeneous particle distribution, is applied by repeatedly passing through a padding for the homogeneous polymer distribution in the fabric, with the finishing process (d) comprising the steps of impregnating (d.l) the fabrics, drying (d.2), and curing (d.3) (pad-dry-cure).

In the step of impregnating (d.l) which comprises applying the solution to the fabric, the padding cylinder pressure specific to each raw material of 2-4 bar, the resulting solution ratio of 80%-100%, the polymer ratio remaining in the fabric in the final state of 5%-7%, and the speed of 1-3 meters/minute are optimized for the different fabrics so that the shape memory and fabric hand performances are optimized.

In the step of impregnating (d.l), the process of passing through the padding at least once, preferably three times with the parameters of the padding cylinder pressure specific to each raw material and fabric of 2-4 bar and speed of 1-3 meters/minute is repeated. The step of impregnating (d.l) is applied until the remaining polymer content in the fabric is between 5% and 7%.

The optimum value range for the step of drying (d.2) is 10-15 minutes at 70-90°C. The optimum value range for the step of curing (d.3) is 5 minutes at 90-120°C.

The method according to the invention also comprises the test applications (e) which determine the performance values to be used in the optimization of the shape memory and fabric hand performances in the step of applying the temperature-moisture responsive nanocomposite structures to the fabrics as a finishing process (d). The tests applied in the invention and the parameters thereof are as follows: • In the air permeability test (e.l) at different fabric temperatures, the air permeability test is performed at the fabric temperatures of 20°C and 40°C, resulting in a minimum increase of 30%-50% in the air permeability.

• In the absorption capacity test (e.2) with the water at different temperatures, the absorption capacity tests are carried out with water at 20°C and 40°C, and as a result of the test, a minimum increase of 5% to 10% in the absorption capacity is achieved in the processed fabric compared to the raw fabric.

• In the water vapor permeability test (e.3) at different ambient temperatures and at different ambient relative humidity values at the same temperature,

■ A minimum increase of 50%-70% in the water vapor permeability is achieved with the increase in temperature in the water vapor permeability test performed at the ambient temperatures of 20°C and 40°C.

■ A minimum increase of 10%-20% in the water vapor permeability is achieved in the water vapor permeability test at an ambient relative humidity of 40% and 65% at 20°C.

• In the test of determining (e.4) the increase in bending rigidity of the processed fabric compared to the raw fabric, a maximum increase of 100% - 150% in bending rigidity of the treated fabric compared to the raw fabric value was determined in terms of maintaining the fabric hand in the second stage of the process. The maximum increase of 100% - 150% in the bending rigidity of the fabric subjected to the nanocomposite finishing process, compared to the raw fabric value, is the value maintaining the fabric hand.

• In the wrinkle recovery and crease retention performance test (e.5) of the treated fabric with water at different temperatures compared to the raw fabric, a minimum increase of 25% in the wrinkle recovery and 65% in the crease retention performance are achieved in the treated fabric with water at 20°C and 40°C compared to the raw fabric.

• In the bagging recovery performance test (e.6) of the processed fabric compared to the raw fabric at different temperatures, a minimum increase of 50% in the bagging recovery performance are achieved in the processed fabric at 20°C and 40°C compared to the raw fabric. The increases in the performance values obtained as a result of the test applications (e) described above show the features of the fabric obtained by the method of the invention. While the invention provides the fabric performance to be increased, it also provides the determination of the optimized parameters suitable for use with the characterization tests that make it responsive to temperature and water/humidity.