Air knives

Air knife coater works in a way similar to a normal knife coater except that the excess of coating is blown off by air under pressure (Fig. 42). This technique works only with very fluid adhesives (less than 500 mPas) with low solids. Also the solvents should dry slowly or else blowing air could cause a skinning over the adhesive surface. When working with a water-based adhesive, the blown air should be saturated with water vapour so that the excess of adhesive could be recycled. Advantages  

Uses The main application is in laminating two plastic films with very low coating thickness. (Readers may refer to the chapter PU Laminating Adhesives for instance, in Volume 4). 

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Air separation Jig separation Pneumatic separation (stoners) Used to separate light (organic) materials from heavy (inorganic) materials in solid waste Used to separate light and heavy materials in solid waste hy means of density separation Used to separate light and heavy materials in solid waste Zig-zag-air, vihrating-air, rotary-air, and air-knife classifiers used with processed wastes shaldng-tahle ... 

Extrusion coating is ideal for rods, tube and wire. The article is passed through a paint reservoir and then out via a die, which leaves only the correct thickness of paint in place. There are further techniques suitable for flat articles in sheet or web form. Knife coating is ideal for very thin coats, especially on continuous paper or plastic webs. The knife is either a metal doctor blade or a curtain of high velocity air (an air knife) directed onto the surface and it removes surplus material applied previously. 

Airjet spinning, cotton yarn, <5 17 Airjet textured yarn process, 20 19 Airjet texturing, 19 753 Air-knife chemical finishing, 17 513 Air knife coating, 7 10-11 method summarized, 7 5t Air-laid processes, 11 179-180 Air legislation (EU), 23 121 Airless atomization, in spray coating, 7 69-70... 

Grace Letterflex Polyurethane with allyl groups Mercaptan Liquid Air knife or water... 

The most popular method to produce sheets is using an extruder with polished stacked rolls that could include the use of an air knife (Figures 5.10 and 5.11). There is the extrusion process where an annular pipe-like cross section die is used (Chapter 17). The extrudate is slit in one or more places and then flattened via rolls into a sheet. In addition to using... 

ASSI Frovifors Bruk, Board mill, Frovifors, Sweden In 1991, two CR filters were installed at ASSl Frovifors Bruk board mUl in Frovifors (Sweden) to concentrate and recover the waste latex coating from an air-knife coater. The 50 kg/mol cutoff polysulfone membrane produces a flux of 200 L/(m h). The mUl uses Ti02 pigment, which makes the recovery process extremely economical. The UF operates at a constant concentrate sohds concentration of 20% continuously for 10 days between cleanings [1,130]. When concentrating a standard coating color effluent steady flux of 120 L/(m h) at a coating color concentration of 10%-15% (50 L/(m h) at 40%) is achieved [36]. 

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