Summary:
This paper briefly introduces the development profile and performance of several common functional textiles, and summarizes domestic testing methods for the special functionality of textiles, providing a basis for functional testing of textiles.
Keywords: functional textiles; UV protection; antibacterial; flame retardant; detection method
Functional textiles generally refer to textiles with other special functions beyond the traditional warmth, covering and beautification functions of textiles [1]. Such as UV protection, moisture absorption and quick drying, antibacterial and deodorant, anti-mosquito, flame retardant, anti-wrinkle and non-ironing, water and oil repellent, fragrance, magnetic therapy, infrared negative ion health care, etc. One or more of the various functions. Functional textiles are generally produced in two ways. One is to use functional fibers to prepare functional textiles. Compared with traditional fibers, functional fibers are also called “new fibers”. They are extracted from special materials and spun. Silk processing, it not only has the functions of conventional fibers, but also has some special functions. For example, chitin fiber is extracted and spun from the shells of shrimps and crabs. This fiber has both antibacterial and moisturizing effects. The second is to perform post-finishing on textiles to obtain special functionality, mainly including padding and coating methods. When textiles are subjected to functional finishing, the required additives and processes must have good environmental protection characteristics, safe production operations, and the final product must have no toxic and side effects, and the final product must have good functional durability.
There are many types of functional textiles, and testing of special functionality has also emerged. Here is a brief description of the performance and testing of several common functional textiles.
1 Performance and test methods of UV-resistant textiles
In recent years, the development of industry has caused the destruction of the ozone layer, and the radiation reaching the ground is increasing day by day. Excessive ultraviolet radiation will cause certain damage to human eyes, skin and immune system. Therefore, the UV protection of textiles has received increasing attention. When ultraviolet rays are irradiated onto a fabric, part of it is absorbed, part penetrates the fibers of the fabric (including passing through the gaps in the fabric), and part is reflected [2]. The more UV rays that pass through the fabric, the greater the damage to the human body. Therefore, the main way to improve the UV protection performance is to enhance the fabric’s ability to absorb and reflect ultraviolet rays, thereby reducing its transmission. Currently, the most widely used way is to enhance the fabric’s ability to absorb ultraviolet rays.
Fabrics treated with post-finishing methods generally have strong absorption and shielding properties for ultraviolet rays in the 280nm~400nm band, and have better protection capabilities for the human body. Currently, the most commonly used anti-UV finishing agents on the market include triazine derivatives and heterocyclic compounds. This type of finishing agent has strong UV absorption ability in terms of chemical structure and is quite popular among manufacturers. In addition, the type and structure of the fabric also have a certain impact on the UV protection performance. Generally, polyester and wool have better UV protection than cotton fabrics because the benzene ring structure in polyester fabrics has a certain absorption effect on ultraviolet rays. The tighter the fabric, the better the UV protection performance, because it is difficult for UV rays to penetrate fabrics with very small porosity, and dark-colored fabrics have better UV protection properties than light-colored fabrics.
The testing method for the UV protection performance of fabrics mainly uses the spectrophotometer method. This method uses a UV spectrophotometer as a radiation source to generate ultraviolet rays in a certain wavelength range (280nm~400nm) and irradiate them onto the fabric, and then uses an integrating sphere to collect the radiation flux in all directions through the fabric to calculate the ultraviolet transmittance. . The smaller the ultraviolet transmittance, the better the effect of the fabric in blocking ultraviolet rays. Currently, the most commonly used index to evaluate the anti-ultraviolet performance of fabrics is the ultraviolet protection coefficient UPF value, which refers to the calculated ultraviolet radiation effect and use when no protective products are used. The calculated ratio of UV radiation effects when used as protective equipment [3]. The higher the UPF value, the better the UV protection performance of the fabric. The sun protection index of cosmetics also uses a similar sun protection factor SPF value.
Our country now adopts the GB/T18830-2009 “Evaluation of UV Protection Performance of Textiles” standard, which stipulates the test methods for the UV protection performance of fabrics, and the expression, evaluation and labeling of protection levels. This standard requires that 4 pieces of homogeneous samples should be taken during testing, and at least 2 pieces of non-homogeneous samples should be taken according to color or structure. According to the tested spectral transmittance, calculate the average transmittance and average UPF value of UVA and UVB respectively. Whether it is a homogeneous or heterogeneous material, the lower UPF value of the tested sample is used as the UPF value of the sample. According to this standard, when the UPF value of the sample is >40 and the transmittance T(UVA)AV<5%, it can be called an "UV-protective product."
2 Performance and testing methods of antibacterial textiles
In the natural material cycle and growth process, bacteria are extremely widespread, and fiber fabrics will inevitably have many bacteria attached to them. Their numbers vary from 103/cm2 to 108/cm2 depending on the environmental conditions and fiber types. According to statistics, there are about 10 to 50 million bacteria per gram of cotton fiber. If conditions are suitable, these bacteria will multiply rapidly. On dirty clothes containing a lot of sweat stains, bacteria can grow by 10% after 24 hours.� As mentioned above, these bacteria may cause skin allergies at least, or endanger human health at worst [3]. For this reason, human beings’ desire for health and comfort has been increasing, and antibacterial fabrics have rapidly developed as sanitary functional fabrics and health-care functional fabrics to meet the needs of society.
Antibacterial textiles can be obtained by performing antibacterial post-finishing on fabrics. The post-finishing generally uses a padding and drying process. Some antibacterial agents can also be bathed with dyeing to enhance the color fastness of the fabric. The most commonly used chitin antibacterial agent on the market is mainly used on cellulose fibers. Its active groups can form covalent bonds with the hydroxyl and amine groups on the cellulose fibers to firmly combine, and its antibacterial principle is It destroys the cell wall of bacteria. Since the intracellular osmotic pressure is 20 to 30 times the extracellular osmotic pressure, the cell membrane ruptures and the cytoplasm leaks out. This also terminates the metabolic process of microorganisms, making them unable to grow and reproduce. Silicone quaternary ammonium salt antibacterial agents are a type of antibacterial agent commonly used in polyester products. These products enter the pores of polyester fibers at high temperatures and are firmly attached to the inside of the fibers. They have good safety and can be efficiently removed. Bacteria, fungi and mold on fabrics, keeping fabrics clean and preventing bacterial regeneration and reproduction.
Antibacterial textiles are divided into dissolving type and non-dissolving type. The antibacterial agent on the dissolving type textiles is easy to precipitate in the aqueous solution, while the non-dissolving type is difficult to dissolve. Antibacterial fabrics are divided into ordinary antibacterial fabrics and high antibacterial fabrics according to their antibacterial efficacy. CAS115-2005 “Health Functional Textiles” jointly issued by the China Association for Standardization and the China Health Care Association provides evaluation indicators for antibacterial fabrics against different bacterial species.
CAS115-2005 “Health Functional Textiles” gives the antibacterial detection method for antibacterial fabrics. Based on the halo method, it is qualitatively determined whether the antibacterial material is a dissolution-type antibacterial fabric. In order to prevent the interference of residual floating chemicals during the processing of antibacterial fabrics, the fabric samples used for testing should be tested after one wash as required. Take 5 to 6 pieces of standard blank samples, antibacterial fabric samples, or non-antibacterial fabric samples of the same type that have been washed once each according to the required specifications. There is a culture medium built into the petri dish. Place the sample flatly on the culture medium coated with bacterial liquid. Invert the petri dish and put it into an incubator for cultivation at a certain temperature and time according to different bacterial species. Measure the width of the inhibition zone to determine whether the sample is a dissolution-type antibacterial fabric. Carry out at least three parallel tests on the same sample and take the average. If the width of the inhibition zone D>1mm, it can be judged as a dissolving antibacterial fabric; if the width of the inhibition zone D≤1mm, it can be judged as a non-dissolving antibacterial fabric.
3Flame-retardant textiles and testing methods
With the rapid increase in the consumption of various types of civil and industrial textiles, especially the increasing demand for various interior decoration, cabin decoration fabrics (curtains, curtains, carpets) and bedding, the number of fires caused by textiles is also increasing. . In the 1960s, developed countries such as Japan, Europe and the United States put forward requirements for flame-retardant finishing of textiles, and formulated flame-retardant standards for various types of textiles, restricting non-flame-retardant fabrics from the types of textiles and applicable places [3]. Table 2 lists the technical regulations on flame retardant performance in China and the United States.
The so-called flame retardant refers to reducing the flammability of materials in flames and slowing down the spread of flames so that they can self-extinguish quickly after leaving the flame and no longer spontaneously ignite.
The basic principle of flame retardancy is to reduce the generation of flammable gases during thermal decomposition and to hinder the basic reactions during gas combustion [4]. Absorbing heat in the combustion area, diluting and isolating the air also plays a certain role in preventing combustion. The limiting oxygen index LOI is usually used to indicate the flame retardant properties of fibers and fabrics. The limiting oxygen index (LOI) is the small volume percentage of oxygen required by the sample to maintain candle-like combustion in a nitrogen and oxygen mixed gas. The higher the limiting oxygen index, the higher the oxygen concentration required to maintain combustion, that is, the more difficult it is to burn. The limiting oxygen index of non-flammable fibers is 35 and above, the limiting oxygen index of flammable fibers is 26~34, the flammable fibers are 20~26, and the limiting oxygen index of flammable fibers is lower than 20.
GB/T5455-1997 “Vertical Method for Textile Combustion Performance Testing” standard stipulates the testing methods for the flame retardant properties of various flame-retardant textiles. The testing principle is: place a sample of a certain size under a specified burner and ignite it, and test under After reaching the specified ignition time, the afterburning time, smoldering time and damage length of the sample [5]. Afterburning time refers to the time the material continues to burn with flame after the ignition source is removed (ignition) under specified test conditions. The smoldering time refers to the time that the material continues to burn without flame after the flaming combustion terminates or the ignition source is removed under the specified test conditions. The damage length refers to the maximum distance of the material damage area in the specified direction under specified test conditions. The shorter the afterburning time and smoldering time, and the shorter the damage length, indicate the better the flame retardant performance of the sample.
As people pay more and more attention to the safety of themselves and the surrounding environment, the flame retardant properties of textiles have become an important safety indicator. Some countries have incorporated the flame retardant properties of clothing fabrics into national fire safety regulations, formulated strict flame retardant regulations, and made clear regulations on the flame retardant properties of textiles.
References:
[1] Xie Yunxiang, Liu Qinghua. A brief discussion on the development status and development trend of functional textiles in my country [J]. Synthesis Technology and Application, 2008 (4): 34-36.
[2] Shang Chengjie. Functional Textiles[M]. Beijing: China Textile Publishing House, 2006.
[3] Gao Ming, Tang Xiaorong. Current status of testing standards for UV protection performance of textiles
［J］. Printing and Dyeing, 2009 (3): 40-43.
[4] Jiang Yaoxing, Yao Guifen. Textile Inspection[M]. Beijing: China Textile Publishing House, 2008.
[5]GB/T5455-1997 Textile combustion performance test vertical method [S].
(Author’s unit: Suqian Fiber Inspection Institute)
Source: China Fiber Inspection Magazine
Extended reading: https://www.tpu-ptfe.com/post/3275.html
Extended reading: https://www. yingjietex.com/product/400D-Polyester-Yarn-Dye-Punctate-Plain-OXFORD-Fabric.html
Extended reading:https://www.alltextile.cn/product/product-76-306.html
Extended reading:https://www.tpu-ptfe.com/post/7736.html
Extended reading: https://www.brandfabric.net/polyester-pongeetpe20d-tricot-laminate-fabric/
Extended reading:https://www.yingjietex.com/product/Full-dull-Nylon-Taslon- Oxford-Breathable-Fabric.html
Extended reading: https://www .yingjietex.com/product/DE-24-Memory-Fabric.html
Extended reading: https://www.yingjietex.com/product/1600D-GRID-OXFORD-Fabric.html
Extended reading: https://www.tpu-ptfe.com/post/9321.html
Extended reading: https://www.china-fire-retardant.com/post/9409.htm
