Dow Corning Corporation

Greensboro, N.C


ABSTRACT


During the last few years the use of fluorochemicals to provide stain repellency and/or stain release properties to apparel goods has rapidly grown. The use of fluorochemicals as well as durable press resins, however, has a detrimental effect on the fabric softness. Providing premium softness is key to satisfy the highly demanding aesthetic requirements of many of todays apparel products. Although softeners based on conventional aminofunctional silicones are well known to provide excellent hand, they significantly impair both the stain repellency and the stain release properties of fluorochemical treated fabrics. This paper presents the results from a recent study where current and new selected organo-modified silicones provide very good softness with minimumtono impact on the fluorochemical properties.


INTRODUCTION


During the last few years the easy care concept has rapidly expanded to include stain resistant features in many apparel applications. The easy care concept now encompasses both minimization of ironing and easiness to clean garments that might have become stained in everyday use. The use of finishes that provide stain release and stain repellency to apparel fabrics, particularly cotton, has shown an amazing growth during these last years.1,2


Fabric manufacturers and chemical manufacturers have made advances in finishing processes to ease stain removal and prevent stain penetration. Today, stain release finishing for apparel cotton fabrics is mostly imparted by the incorporation of low surface energy fluorochemicals. Stain release fluorochemical finishes allow oil and water stains to penetrate the fabric; however, when the fabric is laundered, the stains are easily removed. 3 Fluorochemicals also dominate the stain repellency textile apparel market. Out of all existing textile chemicals, only fluorochemicals have shown the unique property to provide fabrics a low surface energy film with both high oil and water repellency properties to resist penetration of oil and water-based stains (polar and non polar liquids). The repellent products prevent the textile substrate from wetting and soiling by repelling the soiling substances and the adhesion of dry soil. 4 Fluorochemical hybrid finishes, also called dual effect, which contain hydrophilic groups, have also been developed and improved successfully over the most recent years to impart both stain repellency and stain release properties.


Most fabrics finished with durable press resins and fluorochemicals have, however, an important drawback; their handle is generally not acceptable and actually can be considerably harsh. Although selected conventional organic softeners can be used in these systems to overcome this issue, the degree of softness they can provide has fallen short for many apparel applications. This is particularly true with todays high performance and durability requirements where normally higher levels of finishing chemicals are used, which in turn, results in a higher detrimental effect on the fabric handle. Even higher levels of conventional organic softeners may not give the softness level required or these levels may have a negative effect on the stain repellency or release properties, not evident when lower levels where used. In addition to performance requirements, todays highly productive and complex finishing operations require the use of easy to use and trouble free finishing products that can offer stability over a broad range of process conditions and compatibility with most textile chemicals. 5 Thus, the selection of the right softener in order to achieve both premium hand and optimum processability becomes extremely important.


SILICONE SOFTENERS FOR FLUORO-CHEMICAL TEXTILE FINISHING


Silicones, particularly amino-modified silicones, are well recognized as premium fabric finishing agents as they not only provide unsurpassed softness but also improve many fabric physical properties.6,7 However, conventional aminofunctional silicones have shown to impair significantly both the stain repellency and the soil release properties of most fluorochemical treated fabric substrates.


During the last several years, specialty organo-modified silicones have been used in stain release and stain repellency textile finishing, imparting various degrees of softness without degrading significantly the properties provided by fluorochemicals. These materials are generally silicone copolymers or terpolymers and have chemical structures where hydrophilic groups, such as polyalkylene oxide polymers, are arranged in different ways onto the main siloxane backbone. These organo-modified silicone polymers may also contain additional reactive organic groups, such as amines, amides and epoxides, which normally contribute to the softness and/or durability.