Painting processes

Figure A13.9 Single-line painting process for a powder system...

Process requirements (e.g., in pharmaceutical and semiconductor manufacturing, painting processes, plastic injection molding, and breweries)... 

Air quality requirements may be set as content of particles and as content of chemical substances. Other requirements for temperature, humidity, and air speed could be set. One example is the spray painting process, which is very dependent on a minimum relative humidity (RH) level to... 

Quality levels are the result of a ratio of parts defective to parts produced. The current trend is to use parts per million (ppm) but this is not always practical for some processes. Painting processes for instance cannot achieve blemish-free surfaces in the order of one blemish per million parts painted ... 

Various types of surface finishes are available for plastics and RP products, such as smooth, textured, molded-in color, and inmold coating. A textured product surface can be obtained through either a textured mold cavity or a postmold paint process. The former method is the most commonly used. A... 

There are three main steps to current painting processes o cleaning of plastic parts o surface treatments o painting. 

The aim of the modern emnlsion painting process is to deposit a nniform, tongh polymer layer on a snbstrate. At first sight it may be thonght that simply dissolving the polymer (typically polyacrylic) in a snitable non-aqneons solvent wonld be snfficient. However, polymer solntions of the reqnired concentrations ( 50%) are very viscons and organic solvents are not acceptable for the home decoration market as well as being expensive. 

A 300-pound watercolor paper can be scrubbed to remove unwanted paint. The painting surface remains relatively unchanged. Also, 300-pound watercolor paper can absorb large quantities of water and remain unwrinkled. It is not necessary to soak and stretch this paper. During the painting process, it remains smooth and receptive to varying amounts of liquid. 

Difficulties were encountered in the in-painting process for the fills cast on the suction table. Since these fills were accomplished without adhesive, they were even more sensitive to dimensional change by application of moisture than flat paper or hand-cast mends. Some experimentation was done in pre-coloring the pulp with dry pigments. Although this coloring process was extremely effective, it produced a flat, even color which was not aesthetically pleasing. 

Dobson, I. D., Life cycle assessment for painting processes, putting the VOC issue in perspective, Progress Organic Coatings, 27, pages 55-58, 2001. 

Concentration of latex particles in water and recovery of latex particles from wastewaters (painting processes, for example). 

A study of cut open inner surfaces of new automotive bodies revealed that an incomplete paint coat existed Inside those areas that subsequently corroded. The insufficient paint coat resulted from the inability of the spray painting process to reach highly recessed areas, like the Insides of doors or the capillary recesses of butted joints or flanges. The dip-coating process does form a wet paint coat in all recessed areas, but during the subsequent... 

We can continue this painting process indefinitely (provided that we do not run out of colors), and the result for the total rate of coagulation occurring in the population of equalsized particles is... 

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