Page 253 - Handbook of Adhesives and Sealants

222 Chapter Six

gallon of tap water is used. Many commercial detergents such as Oak-
ite (Oakite Products, Inc., 19 Rector Street, New York) and Sprex
(DuBois Co., 1120 West Front, Cincinnati, OH) are also available.
Formulation and processing methods for a mild alkaline cleaning
process and a heavy duty alkaline cleaning process are shown in Table
6.8. The parts are immersed for 8–12 minutes in the hot, agitated
solution. As dirt and other contaminants collect in the bath, more al-
kalinity must be added to restore the pH factor to a suitable level.
The parts are finally rinsed with tap water followed by distilled water.
A wet abrasive method of cleaning consists of scouring the surface
of the adherend with detergent. This process consists of thoroughly
scrubbing the substrate with a clean cloth or non-metallic bristle
brush and a detergent solution maintained at 110–140 F. It is a com-
mon surface cleaning method used for many polymeric substrates.

6.4.1.3 Other cleaning methods. Vapor-honing and ultrasonic cleaning
are efficient treating methods for small, delicate parts. When the sub-
strate is so delicate that abrasive treatment is too rough, contami-
nants can be removed by vapor honing. This method is similar to grit
blasting except that very fine abrasive particles are suspended in a
high-velocity water or steam spray. Sometimes solvents are used as
the liquid medium in vapor-honing operations. Thorough rinsing after
vapor honing is usually not required.
Ultrasonic cleaning employs a bath of cleaning liquid or solvent ul-
trasonically activated by a high-frequency transducer. The part to be
cleaned is immersed in the liquid, which carries the sonic waves to
the surface of the part. High frequency vibrations then dislodge the

TABLE 6.8 Mild and Heavy Duty Alkaline Cleaning Processes for All Substrates
Mild alkaline cleaning method Heavy duty akaline
cleaning method
Cleaning solution tetrasodium pyrophosphate sodium metalsilicate
15 pbw 46 pbw
sodium metasilicate 80 pbw trisodium phosphate
Nacconol 40F (a surfactant) 23 pbw
5 pbw sodium hydroxide
23 pbw
Nacconol 40F 8 pbw
Mixing Mix 6–8 oz of above into one Mix 6–8 oz of above
gallon of water into one gallon of
water
Immersion 160–180 F 160–180 F
temperature
Immersion time 8–12 min 8–12 min