tailieunhanh - Ebook Chemistry & technology of fabric preparation & finishing: Part 2

(BQ) Part 2 book "Chemistry & technology of fabric preparation & finishing" has contents: Handmodification, repellent finishes, soil release finishes, flame retardant finishes, other finishes, mechanical finishing. | CHAPTER 8 HAND MODIFICATION Hand o r Handle are the terms used to describe how a fabric drapes around a n object or feels to the touch. When the fabric becomes stiffer or bulkier, the hand of the fabric is said to be built. Chemicals t h a t accomplish this a r e called Handbuilders. When the hand is made to drape more or to feel silkier, the fabric is said to have been softened. Chemicals that do this are called Softeners. Many softeners are derived from naturally occurring Fats, Oils and Waxes. Sources a n d reactions of fats, oils and waxes have been discussed in a Chapter 3. Some softeners are derived from synthetic raw materials. Many of t h e compounds that work as softeners also function as surfactants or water repellents. These topics a r e covered in greater detail i n other sections. It is hoped t h a t the reader will come to appreciate that certain chemicals can serve many functions as textile finishes a n d processing auxiliaries. I. HANDBUILDERS The purpose of applying handbuilders is to add bulk, weight or stiffness to a fabric. For some fabrics, this change must be permanent and withstand washing and dry-cleaning. I n other applications, the change is temporary so handbuilders are classified as either durable or nondurable. A. Non-durable Non-durable handbuilders are uses impart better over-the-counter appearance to many fabrics. Starched fabrics have a greater consumer appeal than limp fabrics. They also improve the handling of flimsy fabrics in cutting and sewing operations since stiff fabrics are easier to manipulate t h a n limp fabrics. Another reason for nondurable handbuilders is t h a t some fabrics a r e traditionally expected to be stiff. For example, consumers expect Denim jeans to be stiff and boardy. They expect jeans to break in, become soft and comfortable and fade with repeated washing. Most water soluble film forming polymers can serve a s non-durable hand builders. However starch and polyvinyl alcohol are the ones used most .