Textile UV protection
UV protection properties of textiles
Classification of ultraviolet rays:
Ultraviolet rays are divided according to wavelength: near ultraviolet (UVA), far ultraviolet (UVB) and ultra-short ultraviolet (UVC). The degree of penetration of ultraviolet rays into human skin is different. The shorter the wavelength of ultraviolet light, the more harmful it is to human skin. Short-wave UV rays can pass through the dermis, while medium-wave UV rays can enter the dermis.
UPF definition:
At present, domestic and foreign standards generally use the UPF value, that is, the ultraviolet protection factor value, to evaluate the UV protection performance of textiles. The UPF value is the ratio of the average amount of UV radiation to unprotected skin. The larger the UPF value, the better the UV protection performance. .
UPF range:
National standards stipulate that only when UPF>30 and UVA transmittance is less than 5%, it can be called an anti-UV product, and the protection level is marked UPF30+; when UPF>50, it indicates the UV protection performance of the product Excellent, the protection level is UPF50+
1. Inspection method for protection against ultraviolet radiation:
1. Direct natural light irradiation method
2. Instrumental method
2. Testing principle:
Uses spectral radiation, provided by ultraviolet radiation sources
Sufficient and stable ultraviolet radiation energy. The monochromator disperses the ultraviolet radiation energy and then irradiates the sample. An integrating sphere is used to collect and organize the reflections from all directions of the sample. The ultraviolet radiation energy is diffusely reflected. The detector converts them into electricity. Signals are converted into various characteristic values through calculation.
Three evaluation indicators:
UV transmittance
UV blocking rate
Ultraviolet Protection Factor (UPF)
UV Penetration
Textile UV protection standards in various countries:
Regarding how to judge whether textiles have UV protection properties, the American and Australian standards determine UPF ≥ 15, the European standard is UPF > 40 (UVA transmittance 30 ( UVA transmittance < 5%).
UPF value and protection level determined by Australian/New Zealand standards
EU standards:
The EU Standard Textiles – Sunlight UV Protection Performance – Test Method for Clothing Fabrics is mainly aimed at testing the UV protection performance of clothing fabrics, and is not applicable to products that provide long-distance UV protection such as umbrellas, sunshades, etc.
American AATCC standard:
“Performance test of textiles transmitting or blocking ultraviolet rays” is used to test the ability of anti-UV fabrics to block or transmit ultraviolet radiation. The tested samples are divided into dry and wet states. The samples are prepared according to different requirements and tested. The area with high UV transmittance on the fabric sample was tested three times to obtain the average UV transmittance. Based on this, the UPF value, the average transmittance of UV-A and UV-B, and the UV blocking rate of UV-B were calculated.
Chinese National Standard:
Our country calculates the average transmittance and average UPF value of UV-A and UV-B and the UPF value of the sample according to the tested spectral transmittance. For homogeneous materials, when the UPF value of the sample is lower than the mid-to-low value of the UPF value measured by a single sample, the lower UPF value of the sample is reported as the UPF value of the sample; for non-homogeneous materials, the UPF value of the tested sample is reported. The medium and low UPF value is used as the UPF value of the sample. When the UPF value of the sample is greater than 50, it is expressed as “UPF>50”. When the UPF of the sample is > 40 and T (UVA) AV is < 5%, it can be called an "UV-resistant product." According to the definition in the national standard, UPF refers to "the ratio of the average effect of ultraviolet radiation calculated when the skin is unprotected to the average effect of ultraviolet radiation calculated when the skin is protected by fabrics."
UPF is the abbreviation of English Ultraviolet Protection Factor, that is, ultraviolet protection factor.
This definition is relatively abstract. We can understand the physical meaning of UPF in this way. For example, a UPF value of 50 means that 1/50 of the ultraviolet rays can penetrate the fabric.
The higher the UPF value, the better the UV protection effect. However, the national standard for textiles with high UPF value is 50+, that is, UPF>50. Because after UPF is greater than 50, the impact on the human body is completely negligible.
The “Evaluation of UV Protection Performance of Textiles” standard promulgated by the General Administration of Quality Supervision, Inspection and Quarantine stipulates:
A. Only when the UPF value of the sample is greater than 40 and the transmittance of UVA is less than 5%, can it be called an “UV-resistant product”. These two conditions are indispensable. This is a measure of whether a product is a “UV protection product.”
B. UV protection products should have three aspects on the label:
1. National standard number: GB/T 18830-2009
2. UPF value:
3. 40+, or 50+
Remarks:
If the measured value of UPF is: 40<UPF≤50, and the transmittance of UVA is less than 5%, the mark is: UPF40+
If the measured UPF value is greater than 50 and the UVA transmittance is less than 5%, the label is: UPF50+
The protective properties provided by this product may be reduced with long-term use and when it is stretched or wet. sdfwegrthrt
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