Powder blending free flowing blends

Blending of polymer, plasticiser and filler may be carried out using two-roll mills or internal mixers as commonly used in the rubber industry. Alternatively, since the raw polymer is supplied as a free-flowing powder a dry blending process similar to that now widely used with PVC (see Chapter 12) is also used. 

Rotating cone, double cone, drum Tumbling action Blending dry, free-flowing powders, granules, crystals Pharmaceuticals, food, chemicals... 

Dry Color A high-intensity blend of pigments and/or dyes with additives provided to the user in the form of dry, free-flowing powders. 

A range of preblended sizes to satisfy any staple yarn requirement at a reasonable cost. The products are free flowing powders based on acrylic and other vinyl polymers blended with starch. Wax is included in appropriate products. 

An off-white free flowing powder which dissolves in water to give low viscosity size solutions particularly effective for synthetic staple yarns and blends. It can be used alone or in conjunction with starch or C.M.C. One particular advantage over other acrylic sizes is that it can be used as the single ingredient of a size mix where Relative Humidities are high. 

Many of the machines described in the last section can blend solids when they are dry and free flowing as well as when they are damp, pasty, rubbery, or plastic. Mullers, pan mixers, and pugmills are examples. Such versatile machines are needed when the properties of the material change markedly during the mixing operation. In general, however, these devices are less effective on dry powders than on other materials and are heavier and more powerful than necessary for free-flowing particulate solids. 

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