Coating air-knife

Information is given on methods of applying coatings (air-knife coaters, lock coalers, roll coalers and blade coalers) and the development of synthetic latices from SB, NB and AN for coating paper. 24 refs. Articles from this journal can be requested for translation by subscribers to the Rapra produced International Polymer Science and Technology. 

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... 

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]. 

During the development of microencapsulation. Green, Schleicher, and others at NCR went looking for paper companies capable of coating the pressure-sensitive microcapsules onto paper. Appleton s coating capabilities drew their attention, because the company s air knife coater did not require the application of pressure for coating, which would damage the capsules. 

Most high-temperature units have a cool down time of 1-1.5 min. Occurrence of a break means a significant fire risk if the hot surface is below the web. Since air-knife and blade coalers usually coat the surface, this is not a problan. 

Chem. Descrip. Carboxyiated styrene-butadiene emuision Uses Modifier for air knife and blade coating formations, for boxboard coating and some publication grade papers Properties 0.19 p particle size vise. 300 cps pH 6.3 57% bound styrene 50% solids... 

RoU with air knife single layer coating 5-500 mPa s thickness 0.1-120 pm accuracy + 5 % maximum speed 8.2 m/s. OK for pigmented surfaces. Usually not used, prefer slide, curtain or extrusion. Examples book, litho, clay-coated sheet. Spin coating thin films 20 nm + 10%. 

RoU with air knife usually coating flows are unstable because of the action of the air knife. 

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