Metal-to-plastic bond

ABS plastic, a polymer consisting of polybutadiene spheroids is dispersed in a continuous phase of poly(styrene—acrylonitrile). The chromic acid attacks the polybutadiene at a much higher rate than the continuous phase. This gives an excellent microroughened surface with superior metal-to-plastic bond strength. A typical recommended formulation consists of 20 vol % sulfuric acid, 420 g/L chromic acid, and 0.1—1.0% of a fluorocarbon wetting agent. The plastic is treated with this formulation for 6—10 min at 60—65°C. 

The excellent adhesion, high cohesion, low shrinkage on cure, absence of volatile solvents and low creep of the resins have led to important applications as adhesives, particularly for metal-to-metal and metal-to-plastics bonding. As with... 

Specific substrates are described under each classification. Of course, adhesive applications are not limited to joints having only one type of substrate. Metal-to-plastic, aluminum-to-steel, metal-to-wood, glass-to-metal, and an infinite variety of other joint configurations are all possible. In these applications the nature of each substrate needs to be understood and considered in the overall selection of an adhesive formulation and bonding process. 

Polyamide (nylon) Acetone, methyl ethyl ketone 1. Abrasion. Grit or vapor blast or abrade with 100-grit emery cloth followed by solvent degreasing. 2. Prime with a spreading dough based on the type of rubber to be bonded in an admixture with isocyanate. 3. Prime with resorcinol formaldehyde adhesives. Sand or steel shot is suitable abrasive Suitable for bonding polyamide textiles to natural and synthetic rubbers Good adhesion to primer coat with epoxy adhesives in metal-to-plastic joints... 

Tritolyl phosphate (TTP) has been examined as a pretreatment for E-glass in epoxide laminates and thermoplastic adhesives for bonding poly(vinyl chloride) to aluminum, steel to zinc, and acrylonitrile butadiene styrene to aluminum [59]. Mono- and diphosphate esters have been claimed to be suitable adhesion-promoting primers for acrylic adhesives on metal [60,61], unsaturated acid phosphates have been suggested as primers for use on metals to be bonded with free radical initiated adhesives [42], and thiopho-sphate esters have been suggested for adhesives to be used on plastics, ceramics, and metals [62]. 

In present-day high-speed assembly line operations, adhesives are applied robotically. The adhesive bead is apphed quickly and evenly to parts on a conveyor line just prior to being fitted. These operations, especially the need to handle the adhered substrates soon after assembly, demand fast-curing adhesive systems [65]. Two-component adhesives are used to bond metals to plastics in automobiles, to laminate panels in the construction industry, to laminate foams to textiles, to laminate plastic films together, and to bond poly(vinyhdene chloride) films to wood for furniture. A commercial waterborne two-component adhesive is sold by Ashland under the trademark ISOSET. This system is used for exterior sandwich panels by recreational vehicle manufacturers and is composed of a water-emulsiliable isocyanate and a hydroxy-functionalized emulsion latex. 

These are used in bonding metal or reinforced plastic facings to paper (resin impregnated) honeycomb structures, cork and rubber compositions, cyclized and unvulcanized rubbers, steel to vulcanized rubber, and electrical applications. They are also used as primer for metals to be bonded to wood with phenolics. Polyvinyl butyral-phenolics lack the shear strength and toughness of the polyvinyl formal-phenolic type. ... 

Adhesive bonding presents several distinct advantages over other methods of fastening plastic substrates. These are summarized in Table 7.5. Adhesive bonding is often preferred when different types of substrates (e.g., metals to plastics) need to be joined, when high-volume production is necessary, or when the design of the finished part prohibits the use of mechanical fasteners. 

This excellent variant of the simple lap joint is effective for bonding metal to metal (particularly sheet metal) and metal to plastics. Unless gross distortion causes peel and cleavage, normal structural loads induce compression forces in the critical region indicated in Figure 2.31, ensuring very robust joints - particularly with toughened adhesives. 

These are generally termed adherends. A bonded joint may consist of one or more types of adherend material. Where the adherends are materials of a very different nature, e.g. metal to plastic, or metal to glass, the adhesive must also act as a transition layer. For example, where a large difference in thermal expansion coefficient exists between adherends, more flexible adhesives are normally used to allow differential expansion without risking failure. 

These structural adhesives are used in bonding metal to metal in aircraft assemblies, metal honeycomb panels, and wood-to-metal sandwich construction. Other applications include bonding cyclized rubber and, in some cases, vulcanized and unvulcanized rubbers and copper foil to plastic laminates for printed circuits. They are also applied as a primer for metal-to-wood bonding... 

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