Sizing agents for filaments are soluble polymers building up a film on the surface of the fibre and protecting the yarn against any effect of abrasion and mechanical tension that may occur during weaving. Size must be easily applicable, extremely protective during weaving and easily removable or washable during the desizing process.

Moreover, sizes must be easily biodegradable and should not excessively affect the polluting load of the water-treatment plant.

Nowadays, ever-increasing weaving speeds and the greater complexity of fabrics pose more and more interesting challenges on sizing.

Bozzetto Group and chemical auxiliaries for sizing

Bozzetto Group is a European leader in the production of sizing agents for continuous synthetic yarns. Our know-how has its roots in the early ‘70ies, with the industrialisation of this process in production of synthetic fabrics.

At our works in Filago, we produce sulphonated polyester resins for sizing polyester and a range of several acrylic resins for sizing all synthetic fibres. In our application lab, we have 2 pilot plants where we study the developments of new sizes and carry out application tests on the customers’ items.

Our Reutligen Webtester enables us to simulate weaving and to test the performance of several yarns and sizes, to better optimise the products and recipes, and achieve excellent results from the very first tests.

How to carry out the sizing process and where to use the most important auxiliaries

Sizing increases tenacity and resistance to abrasion of warp yarns by building up a protection film that can resist any kind of stress during weaving (cyclic tensions, flexures, abrasion against various parts of the loom and yarn-to-yarn frictions).

The efficacy of the sizing product depends not only upon adhesion between size and yarn, but also upon the capacity to build up a resistant and elastic film.

The properties of the yarn itself and the features of the sizing plant play also an important role.

Application occurs when the warp beam is built up (warping) and it is generally carried out by dipping and squeezing, even if the latest technological developments provide for a tangent application (kiss-roll) with considerable water and energy savings.

Sizing Auxiliaries for Man-Made Fibres

Our Wisester range consists of polyester resins for sizing the continuous polyester yarn for air-jet, rapier and water-jet weaving.

Wisester products have a high chemical affinity for polyester fibres, less sensitivity to room temperature and humidity, excellent compatibility with spinning oils (spin finish).

Low viscosity ensures excellent size penetration and perfect cohesion of the filaments forming the FDY or DTY yarn.

Our range also includes sizing products for PA and PA 66 for water-jet and air-jet looms; these products convey the PA yarn excellent resistance to abrasion and reduce the build-up of loom deposits.

As regards cellulose fibres, our Wisacril range allows for the production of Acetate Rayon or Viscose Rayon linings on state-of-the-art weaving machines, the yield of which is close to 100%.

R&D on auxiliaries for sizing

Sizing products represent an important part of the polluting load in the production of a fabric; the current R&D effort consists in the search for higher performing formulas that can reduce the quantity of product applied to the fabric (size pick-up).

Moreover, it has become essential to suggest some sproducts that can be removed from the fabric more easily as well as to reduce the quantity of water and auxiliaries used during preparation.

We are moving towards a kind of tangent application reducing the water quantity in use and, therefore, the energy consumption necessary to dry the yarn after application; we suggest our range of cold sizing agent, which – in some case – may be also applied without drying (Glicowax).