Soil Release Finish

Principle     

·         Accumulation of soil and dust particles is known as ‘Soiling’.

·      To get rid of this soiling problem, the fabric cannot be made totally soil repellent or   soil resistant but a type of finish is given to the fabric, so that during washing, the   accumulated soil on the fabric can easily be removed from the fabric.

·         This type of finish is known as ‘Soil Release Finish’.

·      Also, the released soil particles should not get redeposit on the fabric during of after   washing.

Objectives

·         This type of finish is mainly given to synthetic fibres.

·     Blouse pieces and some ladies wear also soil release finished because of their easy   absorption of soil.

·        The deposition of soil will reduce the appearance and the real colour of the fabric. So,   it is essential to carry out soil release finish.

·        This is a chemical and property giving finish.

Requirements

·    It should not affect the fastness properties of dyed material and some other physical   properties such as strength, feel, drape etc.

·      It should be fast to light, wash and laundering.

Factors Governing Soiling

·         As the static charge increases, soiling increases.

·         As the moisture regain increases, soiling decreases.

·         As the temperature increases, soiling increases.

·         As the size of the soil particles increases, soiling decreases.

·         As the smoothness of surface increases, soiling decreases.

·         As the denier of the fabric increases, soiling decreases.

·         As the twist of the yarn increases, soiling decreases.

Methods of Bringing Soil Release Property

·         Mercerisation of cotton fabric.

·         Using film forming compounds like CMC, PVA, Starch.

·         Converting the fibre and making it hydrophilic.

·         Using metal oxides like silica alumina, BaSO₄, TiO₂.

·         Using Acrylic polymers with PE, PE glycols, PE emulsion etc.

·         Using silicone emulsions, these are widely used today.

Process for PET fibre

Method:- (1):- Take polyester and pad with a solution containing Polyethylene glycol and 

                       Sodium hydroxide. PAD – DRY Method.

Method:- (2):- Take 1 – 3 % concentrated of Cirrasol PT. Pad- DRY – CURE method.

Method:- (3):- Pad the Polyester yarn with 10 % of NaOH at 60°C for 10 minutes. PAD –

                       DRY Method.

Method:- (4) Pad the polyester with H₃PO₄. PAD – DRY Method.

Process for PET/Woollen blend fibre

·         Soil Release Agents (SRA) :- Migafor or Nonax

Recipe:-           SRA                                        -           50 parts

                        MgCl2.6H2O                          -             5 parts

                        Flourescent Brightener            -  10 – 40 parts 

PAD – DRY – CURE

·         Padding is done at an expression of 60 % followed by drying at a temperature of 70 – 90°C and then curing at 180 – 210°C for 20 seconds.

Process for Nylon fibre

                        Methoxy Methyl nylon           -           0.5 %

                        Catalyst                                   -           3 %

                        PAD – DRY - CURE

Delustring

Introduction

ð  Rayon fibres are having a bright metallic luster.

ð  The high metallic luster of this fibre is not acceptable by the consumer.

ð  Consumer needs a little luster approximately to that of natural silk.

ð  In order to make the highly lustred rayons appear like natural silk, it is necessary to reduce the luster and that is known as DELUSTRING.

Mechanism

            To delustre the bright metallic lustrous fibre, it is necessary:-

(1)   To scatter the light from the external surface.

(2)   To reflect the scattering light in a diffused manner which penetrate into the interior of the fibre.

Methods

1)      Internal delustring

2)      External delustring

 Internal Delustring

ð  In this method the delustring of rayon is done by adding the delustring agent in the spinning bath during the manufacture of filament itself.

ð  Various substances which have high refractive index (more than 1.5) are added in the spinning solutions of the filaments and then the filaments are extruded.

ð  The filaments are finished before the filament formation itself.

Chemical	Refractive index	Delustring effectiveness
TiO2	2.5	0.5 %
Zinc sulphate	2.37	1 %
Barium	1.637	4 %

Advantages of TiO₂

ð  It has a high refractive index of 2.5

ð  It has very small particle size of 0.75 micron and will not block the spinneret.

External Delustring

ð  The mechanism is precipitating some insoluble substances on the fibre using various delustring agent.

ð  An after treatment to rayon fabrics is carried out which is known as external delustring method.

ð  Here, the refractive index and particle sizes are not important.

ð  External delustring can be done by two methods.

·         One bath method

·         Two bath method

ð  These methods involve external white pigment coating uniformly on the surface of the fabric.

One Bath Method

ð  In this method, matting agents are made in advance and applied in presence of certain additives which brings attachment to the fibre.

ð  China clay, aluminium oxide, zinc oxide, titanium oxide and barium sulphate are widely used.

ð  Among with the above compounds 5 % softener, 15 % of resin may be added.

ð  The fabric becomes unnecessarily harsh and stiff by the use of TiO₂.

Two Bath Method

ð  In this method, the fabric is first impregnated with Barium hydroxide.

ð  Chemicals like stearamide can be added in the bath if higher exhaustion is required.

ð  The impregnated fabric is then impregnated again in a bath containing H₂SO₄.

ð  The H₂SO₄ reacts with Ba(OH)₂ to form BaSO₄ which is insoluble.

Ba(OH)₂  +  H₂SO₄  à BaSO₄  +  2H₂O

Process

                        Pad – Dry – Cure

ð  However, the two bath method is the most effective since the surface deposition will be less. The fabric does not become too harsh and stiff.