Continuous coating processes

Continuous Coating Processes Based on Existing Film-Coating Technologies... 

Pentecost B. Continuous coating process. Proceedings of TechSource Coating Technology 99, Atlantic City, NJ, October 12-13, 1999. 

To date, use of such continuous processes has been restricted primarily to the manufacture of large-volume products, an application for which continuous processes potentially have a major advantage. Nonetheless, continuous coating processes provide a potentially viable alternative for the scale-up of any film-coating process, where many of the tasks potentially become much simpler, since they would always be the same irrespective of whether the production batch size is 250 kg or 5(K)() kg. Simplification arises from reducing or eliminating tasks that would... 

Pan coating subclasses primarily are distinguished by the pan configuration, the pan perforations, and/or the perforated device used to introduce process air for drying purposes. Perforated coating systems include both batch and continuous coating processes. 

Early work was carried out in the laboratory by coating batches of urea (I). Later the development was extended to a continuous coating process in a small pilot plant with a production rate of about 135 kg/hr (2). At present, the process is being developed further in a large-scale pilot plant with a capacity of about 1 ton/hr, and the study of operating parameters has been quite encouraging. 

Recently Degussa announced that they have developed Separion separators for lithium batteries by combining the characteristics of flexible polymeric separators with the advantages of chemical and thermally resistant and hydrophilic ceramic materials. Separion is produced in a continuous coating process. Ceramic materials, e.g., alumina, silica, and/or zirconia, are slip-coated and hardened onto a support. ... 

Limited approaches have been made to develop continuous coating processes based on in situ PEDOT. ... 

The use of nylon-11 for powder coatings or dry coatings (qv) has been developed in response to a growing concern for the environment (44) (see Coating PROCESSES, powder technology). Electrostatic deposition allows thin films to be appHed to metal substrates. Once the powder is appHed, it must be melted and coalesced into a continuous plastic film. Eorced draft or irradiant ovens are used for fusion, and because no polymerization or cross-linkage are required for curing, coated objects can be processed quickly and air-cooled (45). 

The primary substrates or support iaclude many types of paper and paperboard, polymer films such as polyethylene terephthalate, metal foils, woven and nonwoven fabrics, fibers, and metal cods. Although the coating process is better suited to continuous webs than to short iadividual sheets, it does work very well for intermittent coating, such as ia the printing process. In general, there is an ideal coater arrangement for any given product. 

Fluxes also contain agents that faciHtate appHcation, such as petroleum jeUy or alcohol. These bum or evaporate at elevated temperatures before the soldering temperature is attained, leaving behind a uniform coating of flux. Fluxes become molten before the joining process is reached. The molten flux flows or spreads to form a continuous coating over the surfaces to which they have been appHed. 

Typical of the temporary or manufacturing aid coating systems is the RISTON dry film photoresist for printed circuit (PC) board fabrication. This was the first of these systems developed. The RISTON product stmcture and the basic steps in its use are shown in Figure 2. It consists of a photopolymer sheet laminated between a Mylar cover sheet and a polyolefin separation sheet. It is manufactured as a continuous web (see Coating PROCESSES, survey), and is suppHed in roUs of varying width and photopolymer composition. 

---