Aerobic acrylic adhesive

A. G. Bachmann, Aerobic acrylic adhesives (new technology in acrylic adhesives), Society of Manufacturing Engineers, Adhesives 84 Conference, 1984. 

B. Reactive Aerobic Acrylic Adhesives—Use and Cure Mechanism... 

C. Increasing Product Quality Through Use of Aerobic Acrylic Adhesives... 

An aerobic acrylic adhesive has also been used to increase both product performance and reliability while reducing assembly costs in the manufacture of motorcycle alternators. A major manufacturer of high-performance motorcycles had been holding ceramic... 

A manufacturer of restaurant appliances fastens a stainless steel top to a combined counter/refrigerator/stove imit. The standard attachment technique included both welding and the use of self-tapping screws. An aerobic acrylic adhesive has replaced these techniques resulting in a lower cost assembly requiring less skilled labor. 

Table 5 shows the difference in labor, time, and by extension, cost between using an epoxy and an aerobic acrylic adhesive. 

In the early 1980s, UV curing grades of aerobic acrylic adhesives, however, were developed to provide structural bonds within seconds at room temperature on a wide variety of substrates. Parts may be precisely positioned and then strueturally joined on demand at both a place and time convenient to the assembly process. 

Wire and component tacking with UV curing aerobic acrylic adhesives has been adopted by a manufacturer of flight systems boards where the need was to tack numerous wires and components in place and reduce manufacturing costs at the same time. Two populated boards with fluorocarbon insulated wires, soldered in various configurations, were bonded in this test. Adhesives being compared were exposed to various mil-standard specifications for humidity, immersion, temperature, and Humiseal coating. 

Acrylic adhesives provide substantial advantages for assembly operations such as fast, room-temperature fixtures, the ability to bond a wide variety of surfaees (even oily metal), bondline flexibility, and good environmental and solvent resistanee. Aerobic acrylic adhesives, owing to their laek of noxious odors, low flammability, and lower toxicity parameters, overcome many of the disadvantages previously associated with acrylic adhesives. In addition, one-eomponent UV light curing grades with superior structural proper-... 

A. G. Bachmann, " Aerobic Acrylic Adhesives - New Technology in Acrylic Adhesives," in Ref. 14. 

A new type of nonvolatile reactive acrylic adhesive, bridging the gap between anaerobic acrylic and volatile reactive acrylic adhesives, has recently been developed. The term "aerobic" acrylic adhesives has been coined solely to identify and to set apart these adhesives from other acrylics it does not necessarily describe their cure mechanism. Their term "aerobic" will be used to refer to a diminished sensitivity to air inhibition of thick layer curing properties and the ability to cure between two surfaces regardless of the presence or the absence of air. 

Aerobic acrylic adhesives are composed or proprietary catalysts, "elastomeric domain" fillers, and low vapor-pressure monomers. Formulations derived from this technology do not exhibit the same sensitivity toward air inhibition shown by other acrylic adhesives. The result is that aerobic acrylics are useable on more porous surfaces and in wider gaps than previously considered practical. 

In cured and curing properties, aerobic acrylic adhesives have a clear advantage for use as a structural adhesive. 

The bonding techniques for aerobic acrylic adhesives are similar to other acrylics. First, the activator is applied to one of the surfaces to be joined as a thin film (quasi monomolecular layer). Roller, brush, and spray methods work equally well as long as the activator layer is kept very thin. While the permissible ratio of activator to adhesive is quite wide, too much activator will lower bond strength. Activators are available in solvents to help... 

An aerobic acrylic adhesive has also been used to increase both product performance and reliability while reducing assembly costs in the manufacture of motorcycle alternators. A major manufacturer of high performance motorcycles had been holding ceramic magnets in place with a plastic retaining ring. The manufacturer had to increase the alternator s output from 17 to 22.5 Amps at 3600 rpm without increasing the size of the alternator. It was known... 

Many kinds of adhesives are utilized in the bonding of loudspeaker magnets, DC motor assemblies, and other types of magnet bonding. Some manufacturers still prefer to use mechanical clamps. The factors that contribute to the choice of a joining process include the cost of the adhesive, labor rates, speed of adhesive fixture, acceptability of odor level, and energy costs. Aerobic acrylic adhesives have been used primarily for their rapid fixture (as little as 10 seconds) resulting in faster assembly rates. 

Aerobic acrylic adhesives have most of the advantages of other acrylic adhesives while offering improvements in cure time, toughness, ease of use, and gap curing ability. The lack of noxious odors are a benefit to adhesive users. 

II. ULTRAVIOLET LIGHT CURING - AEROBIC ACRYLIC ADHESIVES... 

Aerobic acrylic adhesive technology has proven itself remarkably well suited to cures effected by ultraviolet light. Aerobic acrylics cured by UV light have the potential for vastly broadening the market for acrylic adhesives. 

The advantages of "aerobic" acrylic adhesives are retained, and in a few cases, improved upon in their ultraviolet light curing analogues. 

Surface dryness and depth of cure are dependent on both the lamp used and the individual formulation. High intensities are required for the most rapid and deepest cures. A potting grade UV-aerobic will cure to 1/4 inch in 30 seconds under a 100,000 microwatt/cm mercury vapor lamp. Table 7 shows curing times with various lights. Fig. 1 demonstrates a typical cure/intensity relationship of a UV-aerobic acrylic adhesive. 

The ways in which UV-aerobic acrylic adhesives are used have been divided into categories (Table 8). One category is the bonding and lamination of clear materials such as glass and plastics. 

UV-curing aerobic acrylic adhesives, while less expensive on a per pound basis than cyanoacrylates, provide a structural wire-tack that resists environmental conditions. A useful property is that the aerobic acrylics fluoresce to optimum brightness only upon completion of cure, providing a visual means of end-point determination. An elastomer formulation is recommended for permanent wire-tacking in a high vibration environment. Removable wire-tacking formulations are also available (Fig. 1). 

A. G. Bachman American Chemical Engineering Co. is the exclusive worldwide manufacturer of Aerobic Acrylic Adhesives. Elosol, Ltd. of Zurich, Switzerland, supplies our formulations to the European Economic Community. We are negotiating with a number of potential licensees in the Far East. 

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