18-01-2013, 04:34 PM
Spin Finishes
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ABSTRACT
Spin finishes for diverse, polymeric textiles are necessary for efficient process ability and maximum Conversion to functional fibre. Such finishes should provide lubricity, cohesion and increased resistance to static development on the fibre. The emulsifiers, lubricants and antis tats used in fiber Processing differ in reactivity with such polymers. Finish components rely extensively upon derivatives of fats and oils, particularly the numerous emulsifiers used. Certain deficiencies of these finish components, with particular emphasis upon their reactivity with process equipment having Polyurethane surfacing is dis-cussed. Susceptibility of polypropylene to degradation in the Presence of conventional finish compo- nests is examined. Unique properties of polyglycerol esters and glycerido-ester ethoxylates, which over-come these processing difficulties, are considered. The relationship of chemical structure to plasticising activity appears as the key to polymeric fibre resistance to loss of breaking strength.
INTRODUCTION
"Spin finishes" are applied to melt spun man-made fibers to facilitate their manufacture. Selected fatty acid derivatives are the active ingredients in many such pro-cessing aids. These are applied to freshly extruded filament to give a uniform deposit of both lubricating and static retarding compositions which help maintain predetermined fiber properties .Such finishes represent a 30,000,000 lb annual market. Traditional fat and oil technologies thus contribute importantly to textiles designed for fashion and industrial use. A spin finish is a material uniformly deposited upon freshly extruded fiber to facilitate textile machinery pro-cessing of such fiber into yarn and fabric. The term, spin finish, usually used in conjunction with synthetic polymeric fibers, also has analogies in nature. Pure silk is extruded by the silkworm with a protective lubricating covering of sericin, then continuously wound into the cocoon with minimum change in denier or silk diameter. Wool is extruded from the follicle in the skin of the sheep with its accompanying deposit of wool grease sterols. Raw cotton is coated with an invaluable spinning assistant, about 0.3-0.5% cotton wax. Regenerated cellulose immediately absorbs 11% moisture from the ambient air, imparting ease of process ability to cellulosic fibers. Cotton wax is never removed from raw cotton before carding and spinning, nor is raw wool scoured to less than 0.4% grease content. If such solvent soluble lubricants were removed entirely, it would be impossible to card and process both of these natural fibers in a commercially acceptable manner. Generally, synthetic polymeric fibers are of little com-mercial value until a satisfactory spin finish is applied. Choice of a satisfactory finish, enabling full realization one of eight papers being published from the Symposium, "Surface Active Agents in the Textile Industry," presented at the AOCS Meeting, New Orleans, Louisiana, April 1970. of the market potential for a fiber, may require lengthy trials.
FUNCTION OF SPIN FINISH
Spin Finish: As the name suggests, spin finish is the finishing treatment given to the yarn to facilitate the process ability of the yarn during its manufacture as well as in its subsequent processing at the customers end.
It is no exaggeration to say that yarn without spin finish is an incomplete product.
Spin finish is applied to achieve following:
• Lubrication: controls friction.
• Antistatic property: Controls static charge.
• Cohesion of filaments: Controls the filaments in bundle.
• Antibacterial/antifungal/antiseptic agents: Checks the growth of fungi, moulds etc. during storage.
Lubrication
Lubrication is basically a process of adjusting the friction produce during the production process. Under process a manufacturing fiber undergo several different surfaces of metal etc
Antistatic property
One of the most important functions of spin finish is to remove the generated static charges during production process. During texturising and some other process the filament comes in to the contact of ceramic surface and some other metallic surfaces which leads to the formation of electrostatic charges. These charges create difficulty during unwinding.
Providing cohesion
When the filament outcome through the different orifice of spinnerets its need some source of binding .Especially in filament of zero twist , so spin finish provides the required cohesion in filament .
SPIN FINISH CONTITUENT
A spin finish invariably contains large number of chemicals. Major components of a spin finish are-
1. Lubricant
2. Antistatic agent.
3. Emulsifier.
1. LUBRICANTS
Most of the early spin finishes were based on white mineral oils as lubricants. However, with the advent of high speed spinning and friction – texturing processes, mineral oil based finishes lost their importance. During friction – texturing, which is carried out at a high temperatures and high speeds, the mineral oil – based finishes lost their importance.
ANTISTATIC AGENT
There are three ways by which antistatic agents counteract the electrostatic charge. (a) They reduce the coefficient of friction of the fibre; (b) they increase the surface conductivity of the fibre; and © they increase the dielectric constant of the medium between the two bodies in friction, the system fibre – friction body being regarded as a condenser. Numerous chemical compounds have been proposed as antistatic agents. The conventional antistatic agents are mostly long chain alkyl or aralkyl compounds of the non-ionic, anionic or cationic type. The antistatic effect of anionic or cationic compounds is greater when their polar or polarizable nature is greater and the hydrocarbon chain is longer
EMULSIFIERS
The spin finish is generally water insoluble and it is essential to apply its an emulsion. Suitable emulsifiers are therefore required. Various types of emulsifiers used in the preparation of spin finish are: Polyethylene glycols, polyslycerol esters, ethylene ethers and esters, glycol esters, alkanolamides, phosphate esters of fatty alcohols, fatty alcohol ethoxylates, quaternary alkyl amides and alkylol alkyl amides, soaps, sorbitan and polyoxyethylene sorbitan esters, sulfated esters of fatty acides, alcohols, alcohol, ethoxylates, amides, triglycerides, sulfonatede aliphatic as well as aromatic petroleum oils, sulfonated caster oil. Etc.
TYPES OF SPIN FINISH APPLYING TECHNIQUE
The hot filaments extruded from the spinnerets are quenched in a cross flow quench assembly. After quenching the filaments pass over rotating finish rolls where lubricating finish oils are applied to the yarn surface. The rolls are driven by synchronous A.C. motors powered from a common variable frequency source.
The finish solution used in spinning is composed of several ingredients specially formulated in a dilute water solution. The finish ingredients are mixed in a 8% solution with DM water and pumped to the spinning area. In spinning this 8% solution is circulated through finish pans in the machine which feeds the rotating finish rolls. Approx 0.3% finish is applied to the yarn.