What is UV protection fabric

New function finishing---UV finishing

The ultraviolet region of sunlight can be divided into three segments. The region of wavelength 400-320 nm is called UV-A; the region of wavelength 320-280 nm is called UV-B; the region of wavelength 280-200 nm is called UV-C. The UV-C has a short wavelength and has been absorbed in the air and cannot reach the surface of the earth. Ultraviolet rays account for about 6% of sunlight, of which the proportion of UV-A is large and the proportion of UV-B is small. UV-A will penetrate the underside of the epidermis to make the muscles lose their elasticity and the skin is rough and wrinkles. UV-B has skin cancer problems. Therefore, it is required to effectively shield the short-wavelength portions of UV-B and UV-A.

At present, due to the destruction of the Earth's ozone layer by chlorofluorocarbons (ClFCs), the concentration of ozone in the ozone hole found in 1997 was 40% lower than in the 1980s. According to the analysis, if the ozone layer level is reduced by 1%, the transmission of 2% UV-B can be increased, and the incidence of skin cancer is increased by 0.5-5%. According to statistics, between 1980 and 1996, global skin cancer patients doubled. Only the United States has grown from 200,000 in 1990 to 1 million in 1996. [6] Therefore, UV protection of fabrics, especially the UV protection of summer clothing fabrics, is very important.

First, the UV protection agent

UV protectants can be divided into UV absorbers and UV screeners. Most of the former are organic compounds, while the latter are mostly inorganic compounds.

1, UV absorber

(1) Benzophenones The ultraviolet absorption of such compounds relies on the conversion of ketone and enol forms in the molecular structure to convert the absorbed light energy into heat. Uvinue D-49 (BASF) has a plurality of hydroxyl groups in its molecular structure, which has a high adsorption capacity for cotton fibers and can be used as an anti-UV finishing agent for cotton fabrics. After sulfonating the benzophenone compound, it has the property of an acid dye and can be used as an anti-UV finishing agent for silk.

(2) Benzotriazole compounds such as 2-(2'-hydroxy-3'-tert-5-methylphenyl)-5-chloro-benzotriazole (CibaTinuvin 326), etc. Because of its low water solubility, the structure is similar to the disperse dye, and it has a certain sublimation fastness. It can be used as UV protection for the high temperature and high pressure bathing of polyester. However, the benzotriazole compound slightly absorbs near 420 nm, and thus causes some color light changes. DP-UV [5] developed by Shanghai Printing and Dyeing Research Institute is also estimated to be a benzotriazole compound.

(3) Reactive UV absorbers Rayosam series products developed by Clariant, Switzerland, can react with hydroxyl groups on cellulose or amino groups on polyamide fibers, and have good wash fastness. The finished fabric does not change its appearance, feel and aeration.

(4) Aliphatic Polyol Compound [4] Japanese Shiibo Company Product] RICAKGUARD] is a fabric finished with this compound. It has been reported that the finished fabric has a UV transmittance of only 1.6% and a UV transmittance of only 3.4% after 30 washes. It can be used in cotton and polyester/cotton fabrics. The finished fabric has good color fastness, air permeability, and moisture absorption.

2, UV shielding agent

Most of the ultraviolet shielding agents are metal oxides having a relatively high refractive index such as zinc oxide, titanium dioxide and the like. The refractive index of zinc oxide is 1.9, and that of titanium dioxide is as high as 2.6. Since zinc oxide has a relatively low refractive index, the diffusion rate after coating on a fabric is also low, and the transparency is also high. Sumitomo Cement Corporation of Japan developed ultrafine zinc oxide particles (n-100, n-200). The particles are hexagonal. Since the crystallinity is high and the surface energy is small, it is easy to disperse. It can be adsorbed on the fabric in a monodisperse state and has high transparency. Beijing Institute of Clothing Technology has tested zinc oxide treated fabrics with an ultraviolet shielding rate of 89%. The fabric treated with titanium dioxide has an ultraviolet shielding rate of 84.5% and still has 83.6% after five washings.

Since the inorganic ultraviolet shielding agent is resistant to oxidation and oxidation, it can be incorporated into a polyester masterbatch and spun into an ultraviolet shielding fiber. Japan's Kuraray products] Esmer] fiber is an example. [ナウルNEW] of Tokai Painter of Japan is also estimated to be a nano-sized zinc oxide or titanium oxide type shielding agent. The nano-scale ceramic cotton textile developed by Xiamen Huapu High-tech Industry Co., Ltd. of China has anti-ultraviolet, antibacterial and far-infrared thermal insulation functions.

Second, the safety of anti-UV finishing products

1, anti-UV effect

The UV shielding rate is the standard for distinguishing the anti-UV effect of domestic products. Class A: UV shielding rate is above 90%; Class B: UV shielding rate is above 80%; Class C: UV shielding rate is above 50%. Generally, it should be selected as Class A. The shielding ratio is obtained by integrating the transmittance in the wavelength range of 280 to 400 nm.

Australia and New Zealand attach more importance to UV protection. They have developed test standards and evaluation methods for UV-resistant finishing fabrics. The UPF value has been used in 1996 to indicate the UV shielding properties of clothing. It is necessary for China to formulate corresponding standards on the basis of relevant international and foreign standards in order to be in line with international standards and to facilitate product exports.

2, anti-UV finishing product safety

Since the UV-resistant finishing fabric is made in summer, it will directly contact the human skin. To this end, it is necessary to strengthen a series of safety tests such as skin allergy test, acute toxicity test and teratogenic test for anti-UV finishing agent. Make sure the product is safe for humans and environmentally friendly.

Editor in charge: Zhu Ling