Softening finishes

Xiaoli zhang

3.1 Introduction

With chemical softeners, textiles can achieve an agreeable, soft hand(supple, pliant, sleek and fluffy), some smoothness, more flexibility and better drape and pliability.

3.2 Mechanisms of the softening effect Softeners provide their main effects on th

e surface of the fibres ； The physical arrangement of the usual sof

tener molecules on the fibre surface is important ；

It depends on the ionic nature of the softener molecule and the relative hydrophobicity of the fibre surface.

3.3 Product types and their chemistry The softener molecules typically contain a

long alkyl group, sometimes branched, of more than 16 and up to 22 carbon atoms, but most have 18 corresponding to the stearyl residue.

Exceptions to this molecular structure are the special categories of silicones, paraffins and polyethylene softeners.

About one-third of the softeners used in the textile industry are silicone based.

3.4.1 Cationic softeners Cationic softeners have the best softness and ar

e reasonably durable to laundering; provide a hydrophobic surface and poor rewetti

ng properties; usually not compatible with anionic products; Cationic softeners attract soil, may cause yellow

ing upon exposure to high temperatures and may adversely affect the lightfastness of direct and reactive dyes.

Inherent ecological disadvantages of many conventional (unmodified) quaternary ammonium compounds (quaternaries) are fish toxicity and poor biodegradability.

3.4.2 Anionic softeners

heat stable at normal textile processing temperatures;

compatible with other components of dye and bleach baths;

easily be washed off; provide strong antistatic effects and good

rewetting properties;

3.4.3 Amphoteric softeners

good softening effects; low permanence to washing ; high antistatic effects (because of their str

ong ionic character); have fewer ecological problems than simil

ar cationic products; Examples of the betaine and the amine oxi

de type

3.4.4 Non-ionic softeners based on paraffin and polyethylene high lubricity (reduced surface friction) ; not durable to dry cleaning; stable to extreme pH conditions and heat

at normal textile processing conditions; and are reasonably priced and compatible

with most textile chemicals.

3.4.5 Silicone softeners

very high softness, special unique hand, high lubricity, good sewability, elastic resilience, crease recovery, abrasion resistance and tear strength.

show good temperature stability and durability, with a high degree of permanence for those products that form crosslinked films and a range of properties from hydrophobic to hydrophilic.

3.7 Evaluation and testing methods Important components of the sensory per

ception are the smoothness, compressibility and elasticity of the textile sample.

As the hand of fabrics is primarily a subjective feeling – similar to the impression of colour – there have been many efforts to find methods for objective evaluation of the fabric hand.

Relatively simple methods to evaluate only the bending properties of fabric (flex rigidity) are the cantilever method and a similar device called Softometer.

Handle-O-Meter

The Handle-O-Meter is another method in which different kinds of deformation have a simultaneous effect on the sample, resulting in a total value for the hand.

KES-F

The most comprehensive but most expensive method of objective hand evaluation was developed by Kawabata and co-workers21–23 and is called KES-F(Kawabata Evaluation System-Fabrics).

FAST FAST (Fabric Assurance by Simple Testin

g) is another well known system.It was developed for quality assessment in the wool garment industry.

FAST is less expensive and much quicker than the KES-F because it measures only some aspects of the fabric hand such as compression, bending, extension and dimensional stability at a few given points in a simplified form.

3.8 Particulars of and troubleshooting for softening finishes Emulsion stability Softeners and thermomigration of dyes Reactive softeners Volatility Yellowing Deeper colour, darker black Mechanical softening