Views: 0 Author: Site Editor Publish Time: 2024-01-22 Origin: Site
To prevent the damage caused by ultraviolet rays to the skin, from the perspective of textiles, it is necessary to reduce the amount of ultraviolet rays penetrating through the fabric; the effect of fabrics on light is manifested in three forms: light absorption, diffuse reflection, and transmission. Therefore, there are two ways to reduce the amount of ultraviolet rays transmitted:
(1) Improve the reflective ability of the fabric against ultraviolet rays: You can choose appropriate fibers such as fibers with high specific surface area, or use highly reflective materials such as ceramic powder (Mg0, Ti02, etc.) for post-finishing processing of the fabric.
(2) Improve the fabric's ability to absorb ultraviolet rays: that is, use an appropriate ultraviolet absorber to treat the fabric, or add it to the spinning bath during chemical fiber spinning. This method mainly uses its own ability to absorb ultraviolet energy and convert it to a low energy level, turning it into low-energy thermal energy or electromagnetic waves with shorter wavelengths, thereby eliminating the harm of ultraviolet rays to the human body and fabrics.
The anti-UV protection of textiles is to apply a substance that can shield ultraviolet rays on the fabric, and the wearing properties of the fabric after being applied with these substances have basically no adverse effects. At present, the production of UV protective textiles at home and abroad is mainly divided into two categories: one is the UV-resistant fiber method (spinning method), which is made by adding UV-blocking agents during polymerization or spinning, and then , using UV-resistant fibers to produce fabrics; another method is the post-finishing method, which is to use UV-blocking agents through dipping, padding or coating, etc. There are also finishing methods that use microcapsule technology and printing to obtain UV-resistant properties .
3.1 Anti-UV finishing methods
Another method of improving the UV resistance of fabrics is to use certain finishing processes to post-finish the fabrics so that they have good UV resistance. The finishing process for anti-UV radiation finishing of textiles is related to its end use, and the finishing process is roughly as follows The following types:
(1) High temperature and high pressure exhaustion method
The high temperature and high pressure exhaustion method is equivalent to the high temperature and high pressure dyeing of polyester. This method is mainly used for some UV absorbers that are insoluble or poorly soluble in water, such as benzotriazole compounds. Their molecular structures are very close to disperse dyes, so they can enter the interior of the fiber and be fixed under high temperature and high pressure conditions, thus To achieve anti-ultraviolet effect; the ultraviolet shielding finishing of polyester, nylon and other synthetic fiber fabrics can be carried out in the same bath as high-temperature and high-pressure dyeing with disperse dyes. At this time, the ultraviolet absorber molecules dissolve into the fiber, and the fabric can be treated as long as a suitable ultraviolet absorber with low skin toxicity is selected.
(2) Normal pressure exhaustion method
The normal pressure desorption method is mainly used for anti-ultraviolet treatment of natural fiber fabrics such as cotton, linen, wool, and silk with some water-soluble absorbents. This type of textiles only need to be processed in its aqueous solution under normal pressure, similar to dyeing with water-soluble dyes. The absorbent used in this treatment method is a water-soluble UV absorber. For example, some benzophenone-based water-soluble UV absorbers have multiple hydroxyl groups in their molecular structure. In this way, cotton and other natural fibers have better adsorption capacity. Some absorbers can also be used in the same bath as the dye for one-bath dyeing and finishing processing.
(3) Immersion method
The dipping method is to immerse the fabric in the prepared finishing liquid, soak it at a specified temperature for a certain period of time, and then take it out, dry it or perform a certain heat treatment.
(4) Padding method
Since most UV shielding agents are insoluble in water and lack affinity for natural fibers such as cotton and linen, the exhaust method cannot be used. Instead, the shielding agent is fixed on the surface of the fabric (fiber) by bathing it with resin (or adhesive). . That is, the ultraviolet finishing agent and corresponding additives are configured into a solution of a certain concentration according to the usage requirements, and the padding method is applied to the fabric; the padding solution can be composed of ultraviolet shielding agent, resin, softener, etc., and the padding method is to put the fabric into the finishing Soak the liquid in the liquid, and then use a pressure roller to remove the moisture. This is called one dipping and one rolling. It can also be repeated once, that is, two dipping and two rolling. In this way, the finishing agent is squeezed into the fiber through mechanical force, and then dried or Hot roast.
However, after drying and/or heat treatment, the holes in the fabric are easily covered by resin (adhesive), which will affect the style, water absorption and breathability of the finished fabric. The padding method can be divided into pad-baking method, pad-steaming method and pad-batch method; currently, the pad-baking method is more commonly used, and its basic process flow is: padding → drying → heat treatment (baking) → finished product. The pad steaming method and the pad stacking method generally use some UV shielding agents that have reactive properties on the fibers. During the padding → steaming (or stacking) process, the active groups on the shielding agent interact with the hydroxyl groups (-OH) on the fibers. , amino group (-NH2) reacts chemically and is fixed. The mechanism of this process is similar to the process of dyeing cotton and wool with reactive dyes, so it can also be processed in the same bath as reactive dyes.
(5) Stamping method
In order to improve the light (sunlight) color fastness of printed fabrics, UV absorbers can sometimes be added to the printing paste and printed with the dye. Since automobile interior decoration fabrics have high requirements for light fastness, when printing their fabrics abroad, UV absorbers and high light fast dyes are often printed with the same paste.
(6) Coating method
The coating method is to blend the ultraviolet finishing agent and the coating finishing agent, and then uniformly disperse the coating glue to obtain a stable coating glue, which is applied to the fabric with an applicator (such as a scraper, rotary screen printing scraper, etc.), and after necessary baking Dry and heat treatment forms a thin film on the surface of the fabric to achieve the effect of UV finishing. However, the fabric after coating has a tendency to deteriorate in bending performance, air permeability and hand feel.
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