UV protective finish for cotton-polyester fabrics

Every year the number of cases associated with the negative impact of UV rays on human health, as well as on the durability of textiles, is increasing. Ultraviolet (UV) radiation is a significant threat to textile materials, which can lead to deterioration of their properties and premature wear. In the context of global warming and increasing solar radiation intensity, the need to develop materials that can effectively block UV rays is of particular importance. Therefore, the creation of textile materials with improved protective properties against UV rays is an urgent task of the modern textile industry [1-3].

The ability of tissues to resist UV radiation depends mainly on their ability to protect against UV radiation [4,5,6]. The scattering and reflection effects must take into account various factors of the fabric itself, such as the structure of the fabric, the original structure of the yarn, the variety and regularity of the fibers, and the color of the fabric. Dark colors absorb UV rays most effectively, making them the best for preventing UV radiation. The darker the color, the higher its UV protection, such as black, dark blue, dark blue, and dark purple. Bright colors, in addition to dark colors, have the ability to absorb UV rays. For example, a bright red color with a longer wavelength can absorb a significant amount of the sun's ultraviolet rays.

White can only reflect visible light and cannot effectively block UV rays [7].

Thicker fabrics in various types of clothing resist UV radiation more effectively compared to thinner fabrics. Polyester fibers have the highest resistance to ultraviolet radiation due to the presence of a benzene ring in their molecular structure, which allows them to effectively absorb ultraviolet rays. Nylon, cotton, and silk have low UV resistance. Therefore, when choosing clothes resistant to ultraviolet radiation, it is advisable to give preference to denser fabrics containing polyester fibers [8-11].

In recent years, the world's leading studies have shown the effectiveness of using various chemical compounds to protect textiles from UV rays [12, 13]. In particular, work from the USA and Germany demonstrates that the use of nanosized titanium oxide particles can significantly increase UV protection. For example, a 2021 study conducted at the Massachusetts Institute of Technology showed that nano-sized titanium oxide particles can increase the effectiveness of UV protection by up to 95%, while maintaining high breathability of the fabric. Similarly, studies in Japan have confirmed the effectiveness of using sodium hypophosphite in combination with other components to create durable and UV-resistant textile materials [14-17].

For UV-resistant finishes of blended fabrics, impregnation methods are still technically preferred. This process has less impact on fiber properties, fabric style, moisture absorption and strength. In addition, it can be combined with other functional coatings such as antibacterial, deodorizing, hydrophilic, and others. The production of textiles that are UV resistant belongs to the category of textile post-processing. First of all, this involves the application of UV-resistant finishing products, the preparation of finishing solutions and the selection of appropriate finishing processes, absorption or impregnation methods. The process of finishing UV-resistant fabrics depends on the type of fabric and its further use. Therefore, it is necessary to treat textiles with a UV-resistant finish [18, 19].

Materials and research methods

The treatment process included impregnation with solutions: sodium hypophosphite 15-20 g/l, titanium dioxide 3-5 g/l, citric acid 25-30 g/l. The samples were impregnated with the proposed composition in solutions for 2-3 minutes at room temperature, then dried and heat-treated.

Impregnation bath module 200 ml. Sodium hypophosphite and titanium oxide are the main reagents used to create UV protection in textile materials. Sodium hypophosphite acts as a stabilizer to prevent the breakdown of fibers when exposed to UV rays, while titanium oxide, being an effective UV absorbent, blocks the penetration of harmful radiation [20, 21].

Results and discussion

Blended textile materials, due to their composition, have unique properties that can be improved with the correct use of chemicals. The following tissues were chosen as the object of study: polyester 100 % (surface density 180 g/m2), polyester 65 %/ cotton 35 % (surface density 180 g/m2), polyester 65 %/ cotton 35 % (surface density 250 g/m2).

In addition, tests were carried out for physical and mechanical properties to confirm the compliance of products with the established safety standards and quality indicators. A tensile machine was used to determine the tensile characteristics RТ-250М, GOST 3813–72 [22]. The results are presented in the Table 1.

Table 1. Absolute breaking load values for polyester and cotton/polyester blends

№

Textile materials

Component сoncentration, g/l Heat treatment time , 125 оС, time 60 s

15 ^ & о

p 3 1 & o' CD

CD cd' p CD

Breaking load, F (kgf)

processed materials

raw materials

warp

weft

warp

weft

4

r I

4

r I

4

г I

4

г I

1

PE100 % (180 g/m2)

20

5

30

oo

oo о

oo O\

40

2

PE 65%/ cotton 35% (180 g/m2)

oo

Й oo

O\

3

PE 65%/ cotton 35% (250 g/m2)

Й oo oo

о

51

8

According to the data obtained, it is shown that the breaking load of treated textile materials for polyester 100 % was 68,34 kgf, the breaking load of the untreated fabric was 48,02 kgf there is a significant increase in tensile characteristics. For the second two textile materials, the tensile characteristics also increase, the breaking load of the finished samples was 49,157 kgf and 54,23 by base, the raw base 42,59 kgf and 47,01 kgf, according to the density 180 g/m2and 250 g/m2.

Determination of the resistance of the fabric to surface wetting was carried out in accordance with GOST 30292-96 [23], device МТ 032. The degree of water repellency is estimated in conventional units depending on the condition of the wet surface of the sample, the results are in Table 2.

Table 2. Water repellency of polyester and cotton/polyester blends

№	Sample state, conventional units
1	raw materials			processed materials
2	PE100 % (180 g/m2)	PE 65%/ cotton 35% (180 g/m2)	PE 65%/ cotton 35% (250 g/m2)	PE100 % (180 g/m2)	PE 65%/ cotton 35% (180 g/m2)	PE 65%/ cotton 35% (250 g/m2)
3	100	50	60	100	60	80

According to the results obtained, the treatment of textile materials with the developed composition reduces moisture absorption. After hydrophobization, the fabric remains breathable retaining its basic hygienic properties figure 1.

Figure 1. Hydrophobic wetting conditions

From an optical point of view, when light is projected onto an object, some of it is reflected off the surface, some is absorbed by the object, and the rest passes through the object. In general, the sum of transmittance, reflectance and absorption coefficient is 100%. The principle of UV-resistant treatment involves the use of UV blockers to treat fibers or fabrics. When light radiation reaches the tissue, a small part of it passes through the gaps in the tissue, whereas most of it is reflected or selectively absorbed by UV blockers. The absorbed light is converted into low energy, which is then released, effectively blocking UV radiation. The results of the UV protection study were 75-85%, demonstrating the effectiveness of textile material processing.

Conclusion

Studies have confirmed the effectiveness of the use of sodium hypophosphite and titanium dioxide to create textile materials with high protective properties against UV rays. The developed processing methods can significantly increase the durability and safety of textile products, which opens up new prospects for their use in various industries, including protective clothing and interior items, furniture fabrics. The physicochemical properties were studied and the dependence of the physical and mechanical properties of finished textile materials on the chemical structure and physicochemical properties of preparations used for UV finishing was established.

Gratitude, conflict of interest (funding)

The work was carried out at the Almaty Technological University. The authors declare that there is no conflict of interest.