Factors of Ultraviolet Transmission of Textiles and Ways to Reduce Transmission

Ultraviolet rays can cause harm to the human body. The ultraviolet transmittance of textiles is an issue for us to study.

The transmittance of ultraviolet light depends on many factors, such as the structure, coverage factor, color, chemical additives and processing of samples during processing:

1, the structure and structure of the fabric: the denser the woven or knitted fabric, the smaller the amount of ultraviolet light. With the same fabric structure, the UV protection performance increases with the thickness and quality of the fabric, which basically depends on the coverage factor of the fabric.

2. Types of fabric fibers: Different materials have different ultraviolet absorption properties. Both cotton and viscose fabrics have high UV transmission. Bleached cotton fabrics have greater transmission. Wool fabrics and silk fabrics have high ultraviolet absorption capacity. Polyester, due to its aromatic ring structure, has a high UV absorption capacity. Materials with matting agents are easier to absorb UV rays. Nylon fibers pass fairly easily through ultraviolet radiation.

3, the color and shade of the fabric: many dyes absorb ultraviolet rays. In general, darker colors have better protection. Black and dark blue have lower UV transmission.

4. Finishing: UV-treated fabric will affect its UV-resistant performance after repeated washing. Clothing that has not been UV-finished will improve its UV resistance after shrinking.

5. Moisture content: Dry clothes with wet clothes have lower UV transmittance.

    According to scientific analysis, in order to reduce the damage of ultraviolet rays to the skin, it is necessary to reduce the amount of ultraviolet rays transmitted through the fabric, and there are mainly the following ways to reduce the amount of ultraviolet rays transmitted. Ways to reduce UV transmission

    1. High temperature and high pressure exhaustion method

    The high-temperature and high-pressure exhaustion method is similar to the high-temperature and high-pressure dyeing of polyester. This is because some insoluble or hardly water-soluble ultraviolet absorbers have close molecular structures and disperse dyes. Fixation. The high-temperature and high-pressure exhaustion method is suitable for polyester, nylon and other synthetic fiber fabrics. This method is mostly performed simultaneously with disperse dyeing and UV-resistant finishing.

    2. Atmospheric pressure exhaustion method

    The exhaustion law at atmospheric pressure is mainly suitable for UV-resistant finishing of natural fiber fabrics such as cotton, linen, wool, and silk. Atmospheric pressure exhaustion method requires the use of water-soluble UV absorbers. For example, some benzophenone-based water-soluble UV absorbers have multiple warp groups in the molecular structure. Therefore, it can be used for UV-resistant finishing of such fabrics under normal pressure.

    3. Dipping method

    Since most of the ultraviolet shielding agent is insoluble in water and lacks affinity for natural fibers such as cotton and hemp, the exhaustion method cannot be used. Instead, the shielding agent is fixed on the surface of the fabric by bathing with the resin. The padding liquid is composed of an ultraviolet shielding agent, a resin, a softener, and the like. However, after heat treatment, the perforations on the fabric are easily covered by resin, which will affect the style, water absorption and breathability of the finished fabric.

    4. Coating method

    Generally, an appropriate amount of an ultraviolet shielding agent is added to the coating agent, and a precise and fine coating is performed on the surface of the fabric with a coater, and then a film is formed on the surface of the fabric by drying and necessary heat treatment. Although this method makes the washing fastness and the hand feel the impact, it has a wide applicability to fiber types, low processing cost, and low requirements for applied technology and equipment. The ultraviolet shielding agents used in the coating method are mostly high refractive inorganic compounds.

    5.Microcapsule technology and printing method

    Microcapsule technology has been widely used in the industrial field. It is a special packaging form. The substance in the capsule can be solid particles, droplets or bubbles. The anti-ultraviolet finishing agent can be injected into the capsule, so that the outer layer of the capsule is broken due to friction during the wearing process of the clothing, and the effect of slow-release of the anti-ultraviolet finishing agent is achieved; if the photochromic crystal is added to the capsule, the fabric can be discolored Features. In addition to increasing the beauty of photosensitive color-changing clothing, it also enhances the anti-ultraviolet function and can resist long-term ultraviolet radiation.

    The printing method is to prepare an ultraviolet shielding agent or absorbent in a printing paste, and after printing, fix it on the fabric by steaming. This method is suitable for fabrics that do not require high ultraviolet shielding.

    6. Sol--Gel Technology

    General shielding agents have poor washing fastness. As a new multi-purpose tool, sol-gel technology can apply a transparent metal oxide film on the surface of the fabric, which greatly improves the washing fastness. At the same time, it has excellent UV resistance.