Introduction to Functional Textiles

Functional textiles usually refer to textiles with other special functions beyond the warmth, covering and beautification functions of conventional textile products, such as common anti-static, washable (non-iron), shrinkage, mothproof, waterproof, stain-resistant, wrinkle-resistant, anti-pilling, etc., and flame retardant, ultraviolet ray, far-infrared, electromagnetic shielding, anti-bacterial deodorant and odour control, anti-radiation, high hygroscopicity, etc., and these textiles with special functions have only a single function, and some have several functions superimposed, making them multifunctional or composite functional textiles.

Functional textile products are usually classified according to the nature of the fibre, its structure, its performance and its use.

According to the functional properties of the products, they are usually divided into the following four categories: physical functional textiles, chemical functional textiles, material separation functional textiles and bio-adaptive functional textiles.

According to the use of textile performance and purpose, functional textiles can be broadly divided into the following categories:

• Finishing textiles: cotton, wool, silk, linen fabrics, waterproof, wrinkle, dirt finishing, anti-static, anticorrosive mildew finishing;
• Protective textiles: anti-ultraviolet, radiation, flame retardant, high temperature, heat insulation, sound insulation textiles;
• Sensibility textiles: cold feeling, super soft, quick-drying, moisture permeability, high elasticity functional textiles;
• Health care textiles: antibacterial, far-infrared, negative ion health care functional textiles;
• Intelligent textiles: electronic digital fabrics, comfortable and breathable adjustable fabrics, phase change thermoregulation fabrics, colour-changing and hidden colour fabrics, life health care system fabrics, high-performance sportswear and so on.

According to the type of function, they can be divided into: comfort type, protection type, health care type, easy maintenance type, intelligent type and so on.

• Comfort-type textiles refer to textiles that have comfortable functional characteristics, such as moisture permeability and breathability, moisture absorption and quick drying, heat and humidity resistance, warmth, contact with coolness, etc., which can make the human body feel comfortable physiological sensations on the textiles;
• Protective type textiles can provide corresponding protection to the human body to reduce or avoid harm, such as flame retardant, anti-electromagnetic radiation, anti-ultraviolet, anti-static, windproof, waterproof and other functions;
• Health care type textiles with far infrared, negative ions, antibacterial, anti-mould, anti-mite, anti-mosquito and other functions, which can inhibit the reproduction of germs, moulds and other micro-organisms, repel or kill harmful insects, protect human health and prevent diseases;
• Easy maintenance type textiles with non-iron, wrinkle-resistant, easy-to-remove dirt and other characteristics, can reduce the time and frequency of maintenance of textiles, easier to maintain and take care of the cleaning;
• Intelligent type textiles have intelligent adjustment functions when the external environment changes, such as heat storage and temperature regulation, shape memory, self-luminous fibres and their products, positioning, tracking functions, bionic functions, etc.

Functional textile testing

Waterproof, and Moisture Permeability Testing

GB/T 4744 2013 “Testing and Evaluation of Waterproof Performance of Textiles Hydrostatic Pressure Method”

Anti-staining: GB/T 4745-2012 “Testing and evaluation for water resistance—Spray test method” is a method to test textiles waterproofness. The standard divides the anti-staining level into 0-5, with 5 indicating that the textile has excellent anti-staining performance, and 0 indicating that it does not have anti-staining performance, and the higher the level, the better the anti-staining effect of the textile.

Hydrostatic pressure resistance: Hydrostatic pressure resistance simulates the waterproof performance of textiles in a rainstorm environment. The testing method used in the national standard is GB/T 4744-2013 Testing and evaluation for water resistance—Hydrostatic pressure method. The standard stipulates that the hydrostatic pressure resistance of textiles is not less than 4kPa indicating hydrostatic pressure resistance, not less than 20kPa indicating better hydrostatic pressure resistance, and not less than 35kPa indicating excellent hydrostatic pressure resistance. GB/T 21295-2014 “Technical Requirements for Physical and Chemical Properties of Clothing” stipulates that to achieve the function of rain protection, the hydrostatic pressure resistance is not less than 13kPa, and the rainstorm protection is not less than 35kPa.

Test principle

The hydrostatic pressure endured by the fabric is used to indicate the resistance encountered by water through the fabric. Under standard atmospheric conditions, one side of the specimen is subjected to continuously rising water pressure until three seepage points appear on the other side, and the pressure value at the time of the appearance of the third seepage point is recorded, and this is used to evaluate the waterproof performance of the specimen.

Test apparatus

Hydrostatic Head Tester TF163C can measure the water penetration resistance of fabrics under hydrostatic pressure by clamping the specimen on a standard test area. The hydrostatic test can include those kinds of fabrics, such as canvas, coated fabrics, cover cloth, rainproof clothing fabrics, geotextile materials, and films to water penetration under pressure while firmly clamped in the test rig of standard area. Hydrostatic Head Tester TF163C complies with testing standards like AATCC 127, ATSC 127-2008, EN 20811, ISO 811, etc.

Antistatic Performance Testing

Winter clothes many like to use anti-static textiles as fabrics, and there are many standard methods to assess the static performance, product standards are “GB 12014-2019 Protective Clothing Antistatic Clothing”, “FZ/T 64011-2012 Static Flocking Fabrics”, “GB/T 22845-2009 Antistatic Gloves”, “GB/T 24249-2009 Antistatic Clean Fabrics”, “FZ/T 24013-2020 Durable Antistatic Cashmere Knitwear” and so on. Methods standard GB/T 12703.1-2008 Evaluation for electrostatic properties-Part 1: Static half period”,” GB/T 12703.2 -2009 Evaluation for electrostatic properties-Part 2:Electric charge density”,” GB/T 12703.3 -2009 Evaluation for electrostatic properties-Part 3: Electric charge”. Enterprises commonly used 12703.1 assessment of the electrostatic half-life of textiles, so as to assess the grade of the textile, divided into A, B, and C levels.

In the evaluation of the electrostatic properties of textile products, there are resistance indicators (volume-specific resistance, mass-specific resistance, surface-specific resistance, leakage resistance, inter-pole equivalent resistance, etc.), electrostatic voltage and its half-life, charge surface density and other indicators.

In different test indicators reflect different characteristics: half-life reflects the speed of electrostatic decay, charge and charge surface density reflects the degree of friction generated by static electricity, and surface resistivity and point-to-point resistance reflect the strength of the conductive properties.

Moisture Absorption and Quick Drying Testing

At present, the test and evaluation standards of moisture absorption and quick drying and perspiration performance are mainly as follows:

GB/T 21655.1 2008 “Evaluation of absorption and quick-drying Part 1: Method for combination tests”.

GB/T 21655.2 2019 “Textiles-Evaluation of absorption and quick-drying Part 2: Method for moisture management tests”.

Related enterprises can choose the appropriate assessment standard according to the characteristics of their products. Regardless of whether the single combination method or the dynamic moisture transfer method is chosen, it is required that textiles must pass all the relevant moisture-absorbing and quick-drying performance indexes before and after washing before textiles can be claimed to have moisture-absorbing and quick-drying performance.

Comparing the two different test methods and evaluation indexes of GB/T 21655.1 and GB/T 21655.2, the dynamic moisture transfer method test method is relatively simple and convenient to operate, and its evaluation indexes are also more comprehensive and perfect, and its performance requirements can be tested in combination, such as moisture-absorbent quick-drying, moisture-absorbent perspiration, or comprehensive quick-drying, but it does not have the intuitive nature. While GB/T 21655.1 quick-drying test, the core suction height and drip diffusion time is the more direct performance of the fabric’s rapid moisture absorption and diffusion capacity. In the two test methods, moisture absorption and quick-drying test indicators before and after washing to meet the standard requirements (washing procedures and the number of washings customised by the brand, and embodied in the product test report), in order to be called a real moisture absorption and quick-drying products.

Test Apparatus

Moisture Management Tester TF128, is to measure the dynamic liquid transport properties of textiles such as knitted, woven fabrics, and nonwoven textile fabric.

Moisture Management Tester simulates sweat with physiological saline, by measuring the overall dynamic performance of saline in moisture management fabric such as knitted and woven fabrics, then the wetting time of saline through both sides of the fabric, the absorption speed of saline on both sides of the fabric, the diffusion radius of saline on both sides of the fabric, etc., to comprehensively evaluate the sweat absorption and quick-drying performance of the fabric. It can meet a wide range of international standards, such as AATCC 195, and GB/T 21655.2.

Thermal Insulation Performance Testing

At present, in the commonly used domestic test method standards, the common characterisation indexes of thermal insulation performance are thermal resistance and thermal insulation rate. In the domestic product standards, the insulation rate is usually used to evaluate the warmth of the garment, and the thermal resistance is usually only found in the method standards, and the domestic garment product standards rarely use the thermal resistance value as the assessment index.

Standards that can test fabric’s thermal insulation performance are as follows:

ISO 15831 2004 “Clothing—Physiological effects一Measurement of thermal insulation by means of a thermal manikin”.

ASTM F1291 2010 “Clothing Warmth Test Warm Body Dummy Method”.

GB/T 18398 2001 “Testing method for clothing thermal resistance—Thermal manikin method”.

ASTM F 1868 2014 “Test Method for Thermal and Moisture Resistance of Clothing Materials Evaporative Heat Plate Method”.

The thermal resistance of cold-proof garments refers to the performance of cold-proof garments in resisting or preventing the wearer’s body heat dissipation under low-temperature environments.

Clothing thermal resistance is the ability to impede heat transfer due to temperature gradients in the clothing layer, expressed as the ratio of the temperature difference between the inner and outer surfaces of the garment to the heat flow perpendicularly through the unit area of the garment, with the unit of m²•C/W. The unit of thermal resistance that is easy to memorise and understand can also be used: the Crowe (clo).

Test apparatus

TESTEX Sweating Guarded Hotplate TF129 is used to test the thermal resistance and water-vapour resistance of textiles.

Sweating Guarded Hotplate consists of a human skin simulation test board, automatic water supply system, wind speed stabilization system, test host, etc. At the same time, an environmental chamber needs to be configured, because the test board is placed in the environmental chamber in order to meet the requirement for the test. TESTEX Sweating Guarded Hotplate is currently sold to 42 countries and complies with ISO 11092, ASTM F1868, GB/T 11048, etc.

Oil Repellent Performance Testing

It is more commonly used in oil and dirt-repellent functional clothing. Woven textiles can refer to the “GB/T 21295-2014 Requirements of physical and chemical performance of garments” in the technical requirements, in accordance with the method standard “GB/T 19977-2005 Textile-Oil repellency-Hydrocarbon resistance test” to test, to achieve oil repellency level of not less than 4. Other types of textiles can refer to or set their own requirements.

Easy Stain Removal Performance Testing

Woven textiles can refer to the technical requirements in GB/T 21295-2014 Requirements of physical and chemical performance of garments, and test in accordance with the method standard FZ/T 01118-2012 Testing and evaluation for anti-soil properties-

Soil release to achieve the easy stain removal level of not less than 3-4 (native white and bleaching can be reduced by half a level).

(7) Ultraviolet Protection Performance Testing

GB/T 18830-2009 “Textiles-Evaluation for solar ultraviolet radiation protective properties” is the only national method to test the performance of textile UV protection standards. The standard specifies the test method of textile ultraviolet protection performance against sunlight, the expression of the level of protection, evaluation and labelling. The standard stipulates that “when the UPF of the sample is >40 and the T(UVA)AV is <5%, it can be called a UV protection product.”

In recent years, a variety of functional textiles are emerging, people-oriented textile research and development of the guiding ideology, textile performance, multi-functionality and intelligence is the direction of the progress of textile technology. The future of textiles will be towards the development of safety, comfort, health care, convenience, low carbon and other trends.

Preparation of functional textiles and their production status quo

The functional requirements of textiles are different with different purposes of use, and the methods of producing functional textiles are also various, involving both the textile and dyeing and finishing industries, as well as chemical fibres, fine chemicals and other industries.

Making conventional textiles with functionality can be achieved in the following ways:

Firstly, take some special fibres and functional fibres, the development and production of functional textiles with the corresponding functions. Such as the current use of colour cotton, bamboo fibre and other natural fibres and cashmere, camel hair, human hair and other short hair special natural protein fibres and antibacterial fibres, flame retardant fibres and other functional fibres as raw materials, the development of new composite functional textiles.

Secondly, the functional finishing of textiles, that is, the fibres, yarns and finished fabrics using finishing agents for their functional finishing, coating or modification and other finishing methods, to give the product the desired function. Such as the use of organic fluorine finishing durability of oil and water-repellent fabrics, the use of polytetrafluoroethylene coating production of waterproof and windproof and moisture permeable fabrics, antibacterial fabrics with antimicrobial agent finishing and so on.

Thirdly, the use of high-performance such as ultra-high-strength, high-modulus, heat-resistant fibre materials to open the corresponding function of special-purpose textiles, such as the use of aramid production of anti-high-temperature clothing.

3.1 Methods of functional textiles made from functional fibres

Functional fibres can be used in conventional production processes to produce the corresponding textiles. Functional fibre, also known as high-functional fibre, new meaning in addition to “fibre, fabric, clothing” This function at the same time with some special functions. In addition, functional fibre is sometimes given a new special function on the general function of the fibre, which also includes high sensibility fibre, high-performance fibre and high dimensional.

Functional fibres are mostly prepared by the following methods:

• Surface processing of fibres

Surface processing of fibres is to give natural fibres and chemical fibres some new special functions through chemical or physical. The surface method mainly includes the surface treatment method and resin finishing method. The preparation of antistatic fibre adopts the surface treatment method. The treatment can use ionic complexation, in the fibre surface first with cationic anti-processing, and then with anionic antistatic agent treatment so that the fibre surface and cationic surfactant complexes are covered, so as to achieve an antistatic effect.

• Modification of conventional synthetic fibre materials

Through the blending spinning method to add functional additives, this functional add is uniformly dispersed in the fibre so that the fibre has a particular function that can be used in new composite spinning technology to produce ultrafine fibres and internal and external functions of the skin core fibres.

Class functional fibre function can involve far-infrared, anti-ultraviolet radiation, antibacterial, antistatic, negative ions, conductive, etc., fibre, polypropylene-based, varieties include filament, and staple fibre. In recent years out of a variety of inorganic nanomaterials as additives to a variety of functional fibres good momentum.

• Through copolymerisation and other methods to partially change the structure of the polymer, so that access to some special features.

For example, in the hydrophobic synthetic fibre large chain introduced hydrophilic, conductive components, can be in a certain degree of the fibre’s conductivity.

At present, the developed functional fibres on the market are far-infrared fibres ultraviolet fibres, anionic fibres, antibacterial deodorant fibres, light-dimensional, flame retardant fibres, scented fibres, colour-changing fibres, radiation magnetic fibres, nanofibers, conductive and antistatic fibres, these functional fibres undoubtedly for the development of functional textiles to provide a strong raw material support.

3.2 Methods of functional finishing to prepare functional textiles

Ordinary textiles can be endowed with corresponding functions to meet certain special requirements through special finishing processing methods, and the functional finishing of textiles has a strong purpose, good effect and high added value of products. Functional finishing of textiles requires good environmental characteristics, production and operation safety and the final product is non-toxic, has no side effects and has good functional durability.

The methods of textile functional finishing include physical finishing, chemical finishing and bio-ecological finishing, among which physical finishing is divided into three methods: dipping method, dip-rolling method and coating method.

(1) Physical finishing method

  a) Dipping method

The dipping method of finishing agent and solvent to form a uniform solution of the multifunctional finishing agent, with the solution penetrated into the textile fibres within the gap between the fibres, and the fibre surface to form intermolecular surface adsorption and attached to the textile. Due to the finishing agent and textile interactions between the weak force, the combination of fastness is not high, susceptible to the outside world and the use of conditions and the loss of unique features.

  b) Dip-rolling method

Dip-rolling method will be finishing textiles immersed in the solution, after rolling, so that the additives with the solution are extruded into the textile fibre gap. The dip-rolling method is simple and easy to implement, with ordinary sizing equipment can be achieved, the cost is low, but the fabric feel and style characteristics of the solution are slightly greater.

  c) Coating method

The coating method will be scraped onto the textile finishing agent, baking, finishing agent and textile fibres can be part of the graft polymerization reaction or finishing agent between each other polymerization, in the textile outer surface to form a more secure film. This finishing method of a combination of high fastness, durability, and low cost, the disadvantage is that the style of the textile, feel the effect of the finishing agent are greater.

(2) Chemical finishing method

The monomer of the fibre material with some functional macromolecules or monomers for copolymerisation, grafting chemical reaction, so that the fibre material and functional materials closely combined to form a new functional material. Chemical finishing has permanent performance, but this method is technical, costly and difficult to produce.

(3) Bio-ecological finishing method

Bio-ecological finishing method is an emerging finishing method in recent years, widely used as a biologically active biological enzyme to textile finishing, this finishing has a higher security, a low impact on the environment, and the finishing effect is good. As bio-ecological finishing relies on biochemical action, although the finishing effect is good and the function is lasting, the production is difficult and the cost is high, and the influence on the textile hand feel and style characteristics varies with the types of bio-enzymes.

Progress in functional textiles

With the development of science and technology and the multiple requirements for textiles in application fields, the development of functional textiles presents the following trends:

4.1 Diversification and functionalisation of fibre raw materials, composite fibre structure and performance

According to the performance of the required textiles to design the molecular structure of the fibre, material collocation and cross-section morphology, so as to present the functionality of textiles. Such as Japan’s Kuraray company produces Airmint a porous structure of polyester filament, it’s a hollow degree of 0%, is a kind of water-soluble polyvinyl chloride and polyester composite filament. The vinyl is dissolved in hot water at the finishing stage, and it is characterised by being extremely lightweight, having a permanent honeycomb structure, and it reflects visible light, so it is opaque and has excellent warmth retention properties.

In addition, various designs of fibre structure and composition, etc. are carried out to improve moisture wicking, hand feel, lustre, light transmittance properties, and so on.

4.2 Compounding of multiple functions of textiles

A single function of the product has been unable to meet the market demand, a variety of functions of the composite, fine special (ultra-fine special) and high simulation series of products in recent years have become the focus of the development of functional products.

4.3 Application of high technology and special fibres

The development of high and new technology and the use of high-tech development of functional textiles for functional product development has created favourable conditions. First of all, the use of a new generation of high-tech fibres, including temperature-altering fibres, light-altering fibres, scented fibres, thermal insulation and heat storage fibres, high water absorption, antistatic, low melting point, conductive and moisture-conducting, waterproof and breathable and other functional fibres to develop textiles with specific functions. Secondly, the use of nanotechnology to develop new functional products is also the development of functional textiles hotspots, such as self-cleaning functional fabrics; biotechnology to develop new functional textile materials, such as spider silk protein fibres and so on. In addition, the application of special fibres provides a shortcut for the development of functional textiles.

Conclusion

Functional textiles are one of the future development trends of today’s textile and clothing, household and industrial textiles. It will be with fine denier fibre textiles, non-woven fabrics, composite materials, environmentally friendly materials, etc. together constitute the seven future trends of textiles and become the mainstream of the development of textiles. People’s growing material culture and other aspects of the high standards, more requirements on textile and clothing, industrial areas put forward new requirements, functional textiles is to comply with the requirements of the times and get the development, and the development of science and technology for the development of functional textiles to provide a guarantee to ensure that the development of functional textiles flourishes, but also for the development of textile enterprises and product structure adjustment, and has played a greater role in promoting and Improve the added value of textiles.