Saturday, November 16, 2019

SIZING INGREDIENTS

SIZING INGREDIENTS:

The chemicals to be used in preparation of sizing liquor is called sizing ingredients. Sizing ingredients may be classified into two categories:
Primary sizing ingredients
Secondary sizing ingredients

Primary sizing ingredients: 

the names and their roles of primary sizing ingredients are given below:

Adhesive agent: 

The main role of an adhesive agent in the sizing liquor is to form a thin layer (film) on the yarn surface. It is very important ingredient. Major portion of sizing liquor consists of adhesive agent. It penetrates inside the yarn and increases the yarn strength. The protruding fibres also binds with yarn surface and help to increase yarn strength. Hairiness of the yarn reduces too. Film on the yarn surface improves the abrasion resistance and smoothness of warp yarn. Now these days following types of adhesive agents are used in sizing process.

Simple starch:

this is untreated starch powder. Mainly maize starch, sago starch, wheat starch, potato starch are used as adhesive agent in sizing. The viscosity of sizing liquor with untreated starch is always high. It gives poor penetration in the warp yarn. This starch is suitable for sizing of coarse count of yarn up to 20s count.

The viscosity of untreated starch can be improved by adding potassium per sulphate in it and improved viscosity of liquor allow to use it in the sizing of medium count of yarn. It gives best performance in weaving with medium speed of loom. This is cost effective. It helps to control the sizing cost per kilogram of warp.

Thin boiling starch:

it is chemically treated starch. It has lower viscosity than untreated starch. It easily penetrates in the yarn. When warp count increases, the size pick-up percentage is also increased thus concentration of liquor is also increases but viscosity of liquor is kept almost same by using thin boiling starch. It may be successfully used in the sizing of medium count of warp yarn. It is little expensive than untreated starch.

Modified starch:

it chemically modified starch. It has very low viscosity. It gives the best penetration effect in the yarn. It is suitable for all types yarn count. It can be used for sizing of warp of high speed loom. Good quality of fabric results with this adhesive. Maximum efficiency can be achieved by using this adhesive. This is much expensive so that it is used in the sizing of fine count of warp yarn only.

Binding agent:

It is used to make the adhesive film enough strong. The adhesive film has brittleness. When it passes through various kinds of abrasive actions and jerks during weaving, the adhesive film becomes cracked and end breakage results during weaving. The binding agent provides strength to the adhesive film and prevent to become crack. There are many types of binding agents which are being used in sizing at present time. The widely using binding agents in today’s sizing are given below:

Guar gum

Carboxy methyl cellulose (C.M.C.)

Poly vinyl alcohol (P.V.A.)

Polyester binder(R- bind, bilbind PS, eco size)

Acrylic binder (rainsize excel).

Above binding agents are used individually or within combination according to requirement, quality and the warp count are always taken into consideration before selection of binding agents.

Softening agent:

It is used to make the adhesive film more soft and flexible. As we know that the warp yarn passes through different angles, so that the adhesive film becomes crack due to bending movement of yarn. This problem necessitates that the adhesive film should be soft and flexible. Softening agent provides enough softness to the adhesive film. It also makes the yarn surface smooth. Following types of softening agents are used now these days:

Vegetable fats (dalda, refined oil)

Animal fats (mutton tallow)

Synthetic softener (R-soft, textile wax)

Little amount of softener is used in the sizing liquor. It does not affect the costing of sizing process in much scale.

SECONDARY SIZING INGREDIENTS:

The secondary sizing ingredients of sizing agents are given below:

Antistatic agent:

It prevents the generation of electrostatic charge in the warp yarn during weaving. When the warp makes up and down movement during weaving, the ends rub to each other and generates electrostatic charge in the warp. This electrostatic charges cause warp breakage during weaving. Very little amount of antistatic agent is used in the sizing liquor. The types of antistatic agent are given below:

Sepcostate

LV-40

PAA-40

Antiseptic agent:

It is used to prevent the bacteria or mildew formation in the sized beam or fabric woven from sized warp. When the sized warp or fabric remain unused, there are chances of bacteria or mildew formation in humid conditions or rainy season. Some antiseptic agent is added to the sizing liquor to avoid this problem.

Salicylic acid

Zinc chloride

Phenol

Emulsifier

Copper sulphate

Hygroscopic agent:

The main role of the hygroscopic agent in the sizing liquor is to improve the moisture absorption capacity of warp from air. Since we know that the strength of cotton increases by increasing moisture percentage, when the warp absorbs the moisture during weaving, the warp breakage rate is reduced. The majorly using hygroscopic agents are given below:

French chock

China clay 

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