Adhesives

First Adhesives The first adhesives were natural gums and other plant resins or saps. It was believed that the Sumerian people were the first to use it until it was discovered that Neanderthals as far back as 50,000 years made adhesives from birch bark

Animal Protein Type Form and color Preparation and application Strength properties Typical uses Blood, protein Solid and partially dried whole blood; dark red to black bondline Mixed with cold water, lime, caustic soda, and other chemi- cals; applied at room temperature; pressed either at room tempera- ture or 120 o C (250 F)and higher High dry strength; moderate resistance to water and damp atmosphere and to microorganisms Interior-type softwood plywood, some times in combination with soybean adhesive; mostly replaced by phenolic adhesive

Animal Protein A natural animal hide glue made from pure animal protein which has been reconstituted into a cake form to make for a more easily dissolving form of hide glue than typical granules. Excellent adhesive strength for gluing difficult surfaces, and removable with heat or steam

Casein Protein Natural adhesives have many of the same properties that chemical and synthetic adhesives have. Some natural adhesives are quite strong, whilst others are incredibly flexible. Some are waterproof, whilst others are soluble in water. Some are ideal for delicate jobs which require a level of invisibility of the adhesive, whilst others can be used in the construction of large or heavy items of furniture. 

Casein Protein Type Form and color Preparation and application Strength properties Typical uses Casein, protein Powder with added chemicals; white to tan bondline Mixed with water; applied and pressed at room temperature High dry strength; moderate resistance to water, damp atmospheres, and interme- diate temperatures; not suitable for exterior uses Interior doors; discontinued use in laminated timbers

Where's the glue in this picture

Many new adhesives are based on plastic compounds, they have advantages and disadvantages Plastics can be classified in many ways, but most commonly by their polymer backbone (polyvinyl chloride, polyethylene, polymethyl methacrylate, and other acrylics, silicones, polyurethanes, etc.). Other classifications include thermoplastic, thermoset, elastomer, engineering plastic, addition or condensation or polyaddition (depending on polymerization method used).

Polyvinyl Acetate emulsion Type Form and color Preparation and application Strength properties Typical uses Cross-linkable polyvinyl acetate emulsion Liquid, similar to polyvinyl acetate emulsions but includes copolymers capable of cross-linking with a separate catalyst; white to tan with colorless bondline Liquid emulsion mixed with catalyst; cure at room tempera- ture or at elevated temperature in hot press and radio-frequency press High dry strength; improved resistance to moisture and elevated temperatures, particularly long-term performance in moist environment Interior and exterior doors; moulding and architectural woodwork; cellulosic overlays

polyvinyl acetate emulsion As an emulsion in water, PVA is sold as an adhesive for porous materials, particularly wood, paper, and cloth. It is the most commonly used wood glue, both as "white glue" and the yellow "carpenter's glue." PVA is widely used in bookbinding and book arts due to its flexibility, and because it is non-acidic, unlike many other polymers

PVA glue

Elastomeric contact Type Form and color Preparation and application Strength properties Typical uses Elastomeric contact Viscous liquid, typically neoprene or styrene- butadine elastomers in organic solvent or water emulsion; tan to yellow Liquid applied directly to both surfaces, partially dried after spreading and before pressing; roller-pressing at room tempera- ture produces instant bonding Strength develops immedi- ately upon pressing, in- creases slowly over a period of weeks; dry strengths much lower than those of conventional wood adhe- sives; low resistance to water and damp atmos- pheres; adhesive film readily yields under static load On-the-job bonding of decorative tops to kitchen counters; factory lamination of wood, paper, metal, and plastic sheet materials

Elastomer contact This solvent-based contact cement bonds instantly, eliminating clamping. It is strong-bonding, fast drying, oil and waterproof. Recommended for bonding plastic laminates to wood, hardboard, leather, rubber, plywood, laminates, particleboard, canvas and metal. Can also bond wood, aluminum, steel, fabric, copper, rubber, leather and canvas.

Elastomer contact

Elastomeric mastic Type Form and color Preparation and application Strength properties Typical uses Elastomeric mastic (construction adhesive Putty like consistency, synthetic or natural elastomers in organic solvent or latex emul- sions; tan, yellow, gray Mastic extruded in bead to fram- ing members by caulking gun or like pressure equipment; nailing required to hold materials in place during setting and service Strength develops slowly over several weeks; dry strength lower than conven- tional wood adhesives; resistant to water and moist atmospheres; tolerant of out door assembly conditions; gap-filling; nailing required to ensure structural integrity Lumber to plywood in floor and wall systems; laminat- ing gypsum board and rigid foam insulating; assembly of panel system in manu- factured homes

Mastic Forms a surface skin, preventing transfer by touch and dirt pick-up on exposed surfaces. Paintable (after skin has formed). Easy clean-up off non-porous surfaces with mineral turpentine. Convenient to use non-slumping from vertical joints and easily extrudable. Long "open" time assists in the assembly of lap joints. Where can this product be used? Metal Glass Concrete Masonry Timber

Emulsion poly- mer/isocyanate Type Form and color Preparation and application Strength properties Typical uses Emulsion poly- mer/isocyanate Liquid emulsion and separate isocyanate hardener; white with hardener; colorless bondline Emulsion and hardener mixed by user; reactive on mixing with controllable pot-life and curing time; cured at room and elevated temperatures; radio-frequency curable; high pressure required High dry and wet strength; very resistant to water and damp atmosphere; very resistant to prolonged and repeated wetting and drying; adheres to metals and plastics Laminated beams for interior and exterior use; lamination of plywood to steel metals and plastics; doors and architectural materials

Epoxy Type Form and color Preparation and application Strength properties Typical uses Epoxy Liquid resin and hardener supplied as two parts; completely reactive leaving no free solvent; clear to amber; colorless bondline Resin and hardener mixed by user; reactive with limited pot-life; cured at room or elevated tem- peratures; only low pressure required for bond development High dry and wet strength to wood, metal, glass, and plastic; formulations for wood resist water and damp atmospheres; delaminate with repeated wetting and drying; gap-filling Laminating veneer and lumber in cold-molded wood boat hulls; assembly of wood components in aircraft; lamination of architectural railings and posts; repair of laminated wood beams and architec- tural building components; laminating sports equip- ment; general purpose home and shop

EPOXY

Epoxy Bonds a variety of surfaces Dries Crystal Clear so there's no visible evidence of repair Quick setting in 5 minutes No clamping necessary High water resistance Forms a rigid, durable bond Can be used for gap filling (Surfaces need not mate closely) Good chemical resistance Heat Resistant Doesn't yellow over time so is ideal for use on glassware  Where can this product be used? Fixing a broken glass vase Repairing jewellery Toy repairs Fixing ornaments or crockery Fixing your handbag strap Not suitable for bonding plastics such as Polypropylene and Polyethylene or for use on polystyrene

Hot melt Type Form and color Preparation and application Strength properties Typical uses Hot melt Solid blocks, pellets, ribbons, rods, or films; solvent-free; white to tan; near colorless bondline Solid form melted for spreading; bond formed on solidification; requires special application equipment for controlling melt and flow Develops strength quickly on cooling; lower strength than conventional wood adhe- sives; moderate resistance to moisture; gap-filling with minimal penetration Edge-banding of panels; plastic lamination; patching; film and paper overlays; furniture assembly; general purpose home and shop

Hot glue gun

Melamine Type Form and color Preparation and application Strength properties Typical uses Melamine and melamine-urea Powder with blended catalyst; may be blended up to 40% with urea; white to tan; colorless bondline Mixed with water; cured in hot press at 120°C to 150°C (250°F to 300°F); particularly suited for fast curing in high-frequency presses High dry and wet strength; very resistant to water and damp atmospheres Melamine-urea primary adhesive for durable bonds in hardwood plywood; end- jointing and edge-gluing of lumber; and scarf joining softwood plywood

Resorcinol Type Form and color Preparation and application Strength properties Typical uses Resorcinol and phenol- resorcinol Liquid resin and powdered hardener supplied as two parts; phenol may be copolymerized with resorcinol; dark red bondline Liquid mixed with powdered or liquid hardener; resorcinol adhe- sives cure at room temperatures; phenol-resorcinols cure at tem- peratures from 21°C to 66°C (70°F to 150°F High dry and wet strength; very resistant to moisture and damp atmospheres; more resistant than wood to high temperature and chemical aging Primary adhesives for laminated timbers and assembly joints that must withstand severe service conditions

Resorcinol Adhesives formulated from resorcinol-formaldehyde resins or phenol-modified resorcinol-formaldehyde resins are the criteria for wood bonding applications demanding room temperature cure, structural integrity, and waterproof characteristics.

Phenolic Type Form and color Preparation and application Strength properties Typical uses Phenolic Liquid, powder, and dry film; dark red bondline Liquid blended with extenders and fillers by user; film inserted directly between laminates; powder applied directly to flakes in composites; all formulations cured in hot press at 120°C to 150°C (250°F to 300°F) up to 200°C (392°F) in flakeboards High dry and wet strength; very resistant to water and damp atmospheres; more resistant than wood to high temperatures and chemical aging Primary adhesive for exterior softwood plywood, flakeboard, and hardboard

Phenolics Phenolics (PF) or (phenol formaldehydes) high modulus, relatively heat resistant, and excellent fire resistant polymer. Used for insulating parts in electrical fixtures, paper laminated products (e.g. "Formica"), thermally insulation foams. It is a thermosetting plastic, with the familiar trade name Bakelite, that can be moulded by heat and pressure when mixed with a filler-like wood flour or can be cast in its unfilled liquid form or cast as foam, e.g. "Oasis". Problems include the probability of mouldings naturally being dark colours (red, green, brown), and as thermoset difficult to recycle

Polyurethane Type Form and color Preparation and application Strength properties Typical uses Polyurethane Low viscosity liquid to high viscosity mastic; supplied as one part; two- part systems completely reactive; color varies from clear to brown; colorless bondline Adhesive applied directly to one surface, preferably to water- misted surface; reactive with moisture on surface and in air; cures at room temperature; high pressure required, but mastic required only pressure from nailing High dry and wet strength; resistant to water and damp atmosphere; limited resis- tance to prolonged and repeated wetting and drying; gap-filling General purpose home and shop; construction adhesive for panelized floor and wall systems; laminating plywood to metal and plastic sheet materials; specialty laminates; instal- lation of gypsum board

Polyureathane Polyurethane is used as an adhesive, especially as a woodworking glue. Its main advantage over more traditional wood glues is its water resistance. It was introduced in the general North American market in the 1990s as Gorilla Glue and Excel, but has been used much longer in Europe. On the way to a new and better glue for bookbinders, a new adhesive system was introduced for the first time in 1985. The base for this system is polyether or polyester, whereas polyurethane (PUR) is used as prepolymer. Its special feature is the coagulation at room temperature and the reacting to moisture.

Polyurethane http://en.wikipedia.org/wiki/Polyurethane#Adhesives

Urea Type Form and color Preparation and application Strength properties Typical uses Urea Powder and liquid forms; may be blended with melamine or other more durable resins; white to tan resin with colorless bondline Powder mixed with water, hard- ener, filler, and extender by user; some formulations cure at room temperatures, others require hot pressing at 120°C (250°F); curable with high-frequency heating High dry and wet strength; moderately durable under damp atmospheres; moder- ate to low resistance to temperatures in excess of 50°C (122°F Hardwood plywood; furni- ture; fiberboard; particle- board; underlayment; flush doors; furniture cores

Urea It was the first organic compound to be artificially synthesized from inorganic starting materials, in 1828 by Friedrich Wöhler, who prepared it by the reaction of potassium cyanate with ammonium sulfate. It is found in mammalian and amphibian urine as well as in some fish. Birds and reptiles excrete uric acid, comprising a different form of nitrogen metabolism that requires less water.

Urea