Giving polyester textile materials high water repellency by treating them with a solution of tetrafluoroethylene telomers

Abstract

It was shown that solutions of tetrafl uoroethylene telomers in acetone form a coating on the surface of fabric which forms a thin fl uoropolymer fi lm after heat treatment and gives polyester fabrics a high level of water repellency. Methods of acting on the fi bre material that allow additionally increasing the degree of water repellency due to regulation of the thickness and ordering of the fi lm and acting on the microrelief of the fabric were revealed. Preliminary chemical activation of the polyester material and an abrasive effect on its water-repellent coating are proposed for this purpose.Giving textile materials water-repellent properties is an important, widely used method of special fi nal fi nishing. Any textile material, even material consisting of water-repellent synthetic fi bres, has relatively high surface energy that ensures the wettability of its surface with water [1]. To prevent wetting, it is necessary to form a new coating with reduced surface energy on the surface of the fi bres. The generally accepted criterion for assessing water repellency is the contact angle of wetting  (the angle between the tangent to the surface of a drop of liquid at the point of contact of three phases -solid, liquid, and gas -and the surface of a solid, measured inside the liquid phase) [2]. For water-repellent surfaces,  is greater than 90°. Textile materials with elevated water-repellent properties which have ultra-( > 120°) and superhydrophobic ( > 150°) properties are of special interest [3].Organofl uorine compounds are the most effective for reducing the surface energy of textile materials and consequently increasing the water and dirt repellency and improving the launderability. Nontraditional methods of making polyester fabrics water repellent by using fl uoropolymers were developed by the "Fluoropolymer Materials and Nanotechnologies" consortium. The method of making polyester fabric water repellent by treating it with a solution of ultradisperse polytetrafl uoroethylene in supercritical carbon dioxide is examined in detail in [4,5]. Another promising method of making synthetic fabrics waterrepellent is to form a protective coating on their surface by application of tetrafl uoroethylene telomers from solution in acetone [6]. The features of this method and possibility of increasing its effi cacy are examined in the present study.The product based on tetrafl uoroethylene telomers (trade name Cherfl on) was developed and is manufactured at the Institute of Problems in Chemical Physics (IPCP), Russian Academy of Sciences (Chernogolovka) using radiochemical initiation of polymerization of tetrafl uoroethylene monomers ( 60 Co  radiation) [7][8][9]. A mixture of telomers containing more than 90% molecules with an average degree of polymerization of 5-6 and CH 3 -C=O-CH 2 -end groups is formed as a result [7]. The solutions of tetrafl uoroethylene telomers in acetone used in the present study were obtained in a reactor that can maintain a constant concentration of monomer during the reaction [8].

Giving Improved and New Properties to Fibrous Materials by Surface Modification

“…When applied from solutions, some of these oligomers are capable of forming coatings on the surface of filaments with properties similar to those of polytetrafluoroethylene [220,221]. Fluorinated oligomers, obtained either by thermal degradation of fluoropolymers [207,[222][223][224][225][226][227] or by synthesis from fluoromonomers [3,207,211,221,[228][229][230][231][232], are the basis of such coatings. The use of organosilicon compounds as hydrophobizers also significantly reduces the surface energy of fibrous materials [233][234][235][236].…”

“…In this case, the coating will reflect the microrelief of the fibrous substrate, acquiring a similar roughness. In [207,[222][223][224][225][226][227][228][229][230][231][232]263,264], such coatings characterized by high water contact angles were formed from solutions of fluorine-containing hydrophobizer in organic solvents and supercritical carbon dioxide; in [265] by plasma spraying, in [266] by combining electric spinning with chemical vapor deposition of the coating, in [239] by chemical etching, and in [267] by electrochemical deposition. As shown in [222][223][224][225][226][227][228][229][230][231][232]268], the degree of hydrophobicity achieved can be further increased by using the methods of preliminary activation of fibrous materials, which increase the roughness.…”

“…In [207,[222][223][224][225][226][227][228][229][230][231][232]263,264], such coatings characterized by high water contact angles were formed from solutions of fluorine-containing hydrophobizer in organic solvents and supercritical carbon dioxide; in [265] by plasma spraying, in [266] by combining electric spinning with chemical vapor deposition of the coating, in [239] by chemical etching, and in [267] by electrochemical deposition. As shown in [222][223][224][225][226][227][228][229][230][231][232]268], the degree of hydrophobicity achieved can be further increased by using the methods of preliminary activation of fibrous materials, which increase the roughness. However, the technique of increasing the nanoroughness of a fibrous material by creating hierarchical nanostructures based on nanoparticles, which was used in the deposition of thick layers of a hydrophobizer, is ineffective in the formation of ultrathin coatings [269].…”

Wear-Resistant Hydrophobic Coatings from Low Molecular Weight Polytetrafluoroethylene Formed on a Polyester Fabric

“…Changing the synthesis parameters (telogen, monomer concentration, and radiation dose) makes it possible to obtain telomers with the chain length from several units to hundreds of units [20,29,30]. Works [11,18,20,[30][31][32][33][34][35][36][37] show that tetrafluoroethylene telomers synthesized and dissolved in acetone, butyl chloride and trimethylchlorosilane with the chain length of 20-30 monomer units possess a combination of film-forming properties, good adhesion and high thermal stability. These properties of the telomers make them promising water-repellents for fibrous materials.…”