Factors Influencing UV Resistance of Textiles and Improvement Measures
December 12, 2025
Solar radiation includes infrared (IR), ultraviolet (UV), visible light, and other radiations. Ultraviolet rays are a general term for radiations with wavelengths ranging from 0.01 nm to 0.40 nm in the electromagnetic spectrum. Also known as "ultraviolet light", ultraviolet rays can be divided into long-wave ultraviolet (UVA), medium-wave ultraviolet (UVB), short-wave ultraviolet (UVC), and vacuum ultraviolet.
Ultraviolet radiation refers to solar radiation with a wavelength of 290 ~ 400 nm, including medium and long-wave ultraviolet rays (UVA and UVB) as well as short-wave ultraviolet rays (UVC). UVC is absorbed by the ozone layer, so the ultraviolet rays that mainly affect the human body are UVA and UVB.
Textile sun protection mainly targets UVA + UVB. Therefore, international standards uniformly select the range of 280-400 nm as the evaluation spectrum.
Factors Influencing UV Resistance of Textiles
Ultraviolet radiation can also have adverse effects on fabrics. The main factors affecting the UV resistance of fabrics include: fiber type, yarn structure, fabric porosity, fabric structural parameters, color, weight and thickness, and chemical additives. Stretching, wetting, and washing that may occur under daily use conditions can also have a significant impact on UV resistance.
UV-Protective Textiles
Indicators and Standard Requirements
UV protection indicators are mainly used to measure the product's ability to block ultraviolet rays. Common UV protection indicators include the following:
1. UPF (Ultraviolet Protection Factor)
Definition: The ratio of the average effect of ultraviolet radiation calculated when the skin is unprotected to that calculated when the skin is protected by fabric.Numerical Significance: The higher the UPF value, the stronger the product's UV protection ability.Generally speaking, UPF50+ means that the product can block more than 98% of ultraviolet rays.Application: Commonly used for labeling sun-protective clothing, sun umbrellas and other products.
2. UVA Transmittance
Definition: The proportion of ultraviolet A band (wavelength 315nm - 400nm) transmitted through the product.Numerical Significance: The lower the transmittance, the better the blocking effect on UVA.Application: Together with UPF, it is an important indicator for evaluating the performance of sun-protective products.
3. UVB TransmittanceDefinition: The proportion of ultraviolet B band (wavelength 280nm - 315nm) transmitted through the product.Numerical Significance: The lower the transmittance, the better the blocking effect on UVB.Application: It is concerned in some fields with high requirements for UV protection, such as outdoor equipment and optical lenses.
Testing Methods for UV Protection Performance
1. Spectrophotometer Method
Irradiate the sample with monochromatic or polychromatic UV rays, collect the total spectral transmitted rays, determine the total spectral transmittance, and calculate the ultraviolet protection factor (UPF) of the sample.
2. Irradiating Samples with Parallel Light BeamsThe method of collecting all transmitted light with an integrating sphere can ensure that transmitted light from all directions is collected, making the measurement results more comprehensive and accurate. The integrating sphere can effectively homogenize the light and reduce measurement errors caused by uneven light.
3. Irradiating Samples with Hemispherical LightCollect parallel transmitted light, focusing on measuring transmitted light in a specific direction, which can specifically study the optical properties of the sample in a specific direction.
UV Protection Performance Test Standards for Textiles in Different Countries
According to the national standard GB/T 18830-2009 "Evaluation of UV Protection Performance of Textiles", UV-protective textiles must meet UPF > 40 and UVA transmittance < 5% to be called UV-protective products.
Ultraviolet Protection Factor (UPF) refers to the ratio of the average effect of ultraviolet radiation calculated when the skin is unprotected to that calculated when the skin is protected by fabric. The higher the UPF value, the better the UV protection performance of the textile. UVA is the longest wavelength part of ultraviolet rays, with strong penetration, which can reach the dermis layer of the skin and damage elastic fibers and collagen fibers. The smaller the UVA transmittance, the better the UV protection performance of the textile.
Approaches to Improve the UV Protection Performance of Textiles
1. Azo dyes can absorb ultraviolet radiation and prevent photodegradation of polymers;
2. Use fibers with high UV protection factor to weave fabrics;
3. Add particles with UV protection function during fabric weaving;
4. Change the fabric structure, such as increasing fabric thickness and density;
5. Add an appropriate amount of UV finishing agent to the fabric to achieve UV resistance and sun protection functions.
UV Resistance Mechanism of Fabric Fibers and Fabrics
When ultraviolet rays irradiate the fabric surface, part of the ultraviolet rays will be transmitted, absorbed and reflected by the fabric. The following figure shows the textile structure and different propagation paths of ultraviolet rays on the fabric surface. The fibers on the fabric surface reduce the harm caused by ultraviolet radiation to human skin by absorbing part of the high energy of ultraviolet rays and converting it into other forms of energy, while the other part of the radiation is reflected or scattered by the fibers themselves.
Therefore, ultraviolet screening agents can be used for certain chemical treatment of fibers or fabrics. Its main mechanism of action is to reflect most of the ultraviolet rays or selectively absorb them, and convert these high energies into low energies for release, thereby achieving the effect of ultraviolet protection. There are many methods to achieve this effect.
This article mainly introduces the achievement of protection through finishing agents.
UV-Resistant Finishing Agents
UV-resistant finishing agents are suitable for UV-resistant finishing of various fiber types of textiles, such as outdoor sportswear and all clothing worn for outdoor work. They can effectively prevent UV radiation and improve the sun protection performance of fabrics. When used in the same bath with polyester dyeing, the color change is small.
Performance
• ✓ Has absorption effect on ultraviolet rays, significantly reduces ultraviolet transmittance, effectively prevents UV radiation (UVA, UVB), and the fabric has a high sun protection index;
• ✓ Good wash resistance and excellent compatibility with resins, softeners and optical brighteners;
• ✓ Usually suitable for all fiber materials, but if fiber matting agents are used or the fabric structure is too loose, the finishing effect will decrease;
• ✓ Does not affect the hand feel of the fabric and has little impact on the shade of the fabric;
• ✗ May be incompatible with other post-finishing products. It is recommended to pre-test its compatibility and effect.
Application
Shake well before use to ensure the best effect.
Recommended Dosage: 20～50g/L for padding method
Recommended Process: Dilute the working solution → (pad-dry, pick-up rate 70～80%) → dry → set
The dosage can be appropriately increased or decreased according to actual needs.
When the initial UPF value of the fabric is very low or the required UPF value is very high, it is recommended to increase the dosage to 50～80g/L.