1. Forestry 485 Lecture 3-7: Mastics, Hot Melts, etc.

2. Mastics Very high viscosity and tack Paste-like consistency High solids, low solvent Common form of construction adhesives e.g., Polyurethane adhesives are commonly supplied as a mastic e.g., Polyurethane adhesives are commonly supplied as a mastic General purpose home, shop, construction adhesive General purpose home, shop, construction adhesive Some used for industrial production of wooden I- beams Some used for industrial production of wooden I- beams

3. Mastic Composition Composition varies widely; may contain: Rubber (natural, synthetic, recycled); latex in water or dispersion in solvent Rubber (natural, synthetic, recycled); latex in water or dispersion in solvent Tackifiers: Rosin, resin, phenolics, resorcinolics Tackifiers: Rosin, resin, phenolics, resorcinolics Fillers: Carbon black, chalk, zinc oxide, clay Fillers: Carbon black, chalk, zinc oxide, clay Plasticizers, antioxidants, curing agents, other Plasticizers, antioxidants, curing agents, other

4. Mastic Uses Mastics are common construction adhesives supplied in tube or can, used to bond: Ceramic, plastic, metal, asphalt, or acoustical tile Ceramic, plastic, metal, asphalt, or acoustical tile Hardboard and wood paneling Hardboard and wood paneling Wallboard, furring strips Wallboard, furring strips Flooring: Wood and synthetic Flooring: Wood and synthetic Countertop laminates Countertop laminates Many, many others! (see Marra, p. 68 for additional items) Many, many others! (see Marra, p. 68 for additional items)

5. Mastic Use Require only nailing pressure to effect a good bond. These adhesives generally have good dry and wet strength. HOWEVER, they do not stand up well to repeated cyclic moisture exposure. HOWEVER, they do not stand up well to repeated cyclic moisture exposure. Good gap-filling ability.

6. Hot Melts 100% Solid Thermoplastics Pellets, blocks, chips Pellets, blocks, chips Set (harden) within seconds upon removal of heat source (“heat-loss adhesive system”) Used extensively for edge-banding, veneer splicing, and similar applications

7. Common Types of Hot Melts Polyamide Typical application: Veneer splicing Typical application: Veneer splicing Low melt viscosity aids glue spread and wetting Low melt viscosity aids glue spread and wetting Rapid setup upon cooling Rapid setup upon cooling Ethylene-vinyl acetate (EVA) Typical application: Edge banding & veneering Typical application: Edge banding & veneering High viscosity at application temperature; 50,000 to 60,000 cps at 200 o C High viscosity at application temperature; 50,000 to 60,000 cps at 200 o C

8. EVA Glues are also used for Hobby, Industrial Assembly, and Packaging Industrial EVA stick applicators Industrial EVA slug applicators Industrial EVA granular applicator for package closing www.impact-adhesives.com