Лако-красочные материалы — производство

The emergence of the DH acrylic adhesives occurred concurrent with the introduction of the so-called ‘‘HP’’ or ‘‘high performance” acrylic adhesives. This type of system, as with the DH types, offered users the ability to bond through oily metals, but did not require the use of awkward oily primers. They also were based on formulations that contained specialty adhesion promoting components, often contained monomers that were less flammable than first generation products, and often were also considerably lower in odor.

Adhesives of HP type have been shown to bond bronze, lead, nickel, magnesium, copper, aluminum, steel, and stainless steel, in addition to most of the other substrates that earlier offerings were capable of bonding. They did, however, continue to show weaknesses when zinc surfaces were bonded. So these adhesives may not be well suited for certain applications in the automobile area where galvanized steel is being bonded (Note that later generations covered in this chapter do not necessarily have this shortcoming).

Table 3 gives the lap shear bond strength of typical substrates bonded with high performance acrylic adhesives. It can be seen from these data that bonds to oily metals are at least as strong, and often stronger, than bonds obtained with clean surfaces. When HP acrylics were used to bond oily metals, and the bonded parts were subjected to aggressive environments (e. g., condensing humidity, salt spray, water immersion, and gasoline immersion) for up to 1000 hours, little or no reduction in overall bond strength was reported.