Warp sizing

It is used in adhesives, paper coating and sizing, and textile warp size and finishing applications. 

Modified starches may be acid-modified, oxidized, or heat-treated. Acid-modified (thin-boiling) starches are used mainly in textiles as warp sizes and fabric finishes. Here they increase yam strength and abrasion resistance and improve weaving efficiency. Tbin-boiHng starches also have selected appHcations in paper and laundry starch preparations. 

Oxidized starches, usually those prepared by hypochlorite oxidation, ate used in paper coatings and adhesives (qv) to improved surface characteristics for printing or writing. Oxidized starches may also be employed as textile warp sizes and finishes, in manufacture of insulation and... 

Low DS hydroxyethyl starches are used as paper coatings and sizes to improve sheet strength and stiffness. They are also employed as paper-coating color adhesives, and to increase fiber bonding in paper products. Hydroxyethylstarches are also used as textile warp sizes. 

Lighdy derivatized starch acetates are employed in food because of the clarity of their gels and their stabiHty. AppHcations include frozen fmit pies and gravies, baked goods, instant puddings, and pie fillings. Starch acetates are used in textiles as warp sizes and in paper to improve printabiHty, surface strength, and solvent resistance. 

The emulsion formulations are generally appHed to cloth by padding from a bath and squeezing off the excess. Modifying a formulation in the pad box, eg, to increase or decrease firmness, can be easily done by adding an emulsion or softener. The alkaH-soluble vinyl acetate copolymers previously mentioned can be used as warp sizes during weaving. 

Starch acetates [9045-28-7] are made by reaction of starch with acetic anhydride. Starch acetates are used in foods to provide paste clarity and viscosity stabiHty at low temperatures. A waxy maize starch acetate is most commonly used. Waxy maize starch acetates for food use are often cross-linked. Acetylated starches are also widely used in warp sizing of textiles. 

Polyester resins can be highly beneficial as additives to other size polymers, although a great deal of care and expertise is required in formulation [192]. Viscosity, for example, is an important factor in the warp sizing process. The viscosity of some sizes, such as poly(vinyl alcohol), is significantly affected by temperature fluctuations. The addition of a polyester resin tends to minimise such changes in viscosity. Surface tension is another important parameter... 

Despite present trends toward use of synthetic polymers developed over the last 10 or 20 years, starches are still being widely used as an adhesive in such applications as the production of paper and paperboard products, warp sizing, and bonding charcoal briquettes. Because of a unique combination of properties and low cost, these adhesives are almost impossible to exclude from many applications, especially those involving the use of hot paste (size) for anchoring fibers. For starch molecules to act as an adhesive, they must be chemically or thermally hydrated. Then, their adhesive character is developed and modified in different ways by chemicals or other additives for different end uses. As renewable resources that are both economical and reliable, starch and dextrin are likely to continue to be significant factors in the adhesive market for many years. 

In the past several years, between 100 and 150 million pounds of starches and dextrins have been used by the textile industry for weaving and finishing cloth, almost 85% of which is acid-modified and derivatized starches. Very little dextrin or unmodified starch is used in warp sizing. 

Effects of preparation Residual waxes, warp sizes, or other hydrophobic materials... 

Amylases Standard procedure for the removal of starch warp size... 

Uses Coatings, hand modifiers, finishes, warp size additives Advantages Economical, easily compounded... 

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