VARIOUS TYPES OFADHESIVES1.Latex Adhesive2.Neoprene Adhesive3.Polyurethane Adhesive4.Hot-Melt Adhesive5.Pressure Sensitive Adhesive
The Main Classes OfAdhesive Used In FootwearIndustry1.Vegatable Pastes2.Rubber Latex3.Natural Rubber Solution5.Neoprene or Polychloropene Adhesives6.Polyurethane Adhesive7.Hot-Melt Adhesive8.Nitrocellulose Adhesive
1.Vegetable Pastes: It is made from starch or dextrin, are mainly used in the trade for labeling boxes.2.Rubber Latex: It is an aqueous emulsion of natural or synthetic rubber stabilised with ammonia . It normally contains 40 to 60 % solids. In sole attaching, this adhesive is used mostly to the bond leather temporarily to natural crepe.3.Natural Rubber Solution: which is a solution of a natural rubber dissolve in solvents such as carbon tetrachloride or benzene, can be used for making permanent bonds of crepe to crepe.
4.Neoprene Adhesive: are more correctly called polychlro-prene adhesive because Neoprene is the trade name of DU Pont for polychlro-prene.5.Poly-urethe Adhesive: It have different properties, depending on their molecular structure . Although aqueous poly-urethe emulsion are now being develop for sole bonding, of resin but with some stabilizers.6.Hot-Melt Adhesive: It have a plastics material rather than synthetic rubber as their basic material. The most successful are polyester or polyamide resins and, to a lesser extent,EVA,a co-polymer of polyethylene and vinyl acetate.
7.Nitrocellulose Adhesives: are made from nitro- cellulose dissolve in strong solvents of the acetone group .these adhesive were the first synthetic adhesive used in the footwear industry but really never satisfactory . They have long since been replace by neoprene & polyurethane adhesives.
The Selection Of BestAdhesiveThe main points to be considered when selecting adhesives for footwear manufacture are:1.Cost2.Strength3.Sutability for use with shoe materials4.Sutability for shoe in processes5.Shelf & pot life6.General Considerations
PRECAUTIONS ON USE OFADHESIVES Many adhesives are available for specific end use. one has to find out an ideal adhesive for specific requirements. The adhesive manufacturers have to educate the users about the limitations on the use of individual adhesive and train the operators on the proper use of adhesive materials. Testing and establishment of realistic quantity control procedures. Safety in handling of materials,before,during and after use. Customer service satisfaction requires a close working relationship between the supplier and user.
Neoprene AdhesiveIt is the generic term for synthetic rubber-like polymers of- chlorobutadience(chloroprene),or copolymers with chlorobutadience as the main constitutent.These are usually dissolve in blends of aromatic aliphatic hydro- carbons & polar solvents such as MEK . The blends of solvents give adhesives with varying viscosities & drying rates As with more solvent baseadhesive,neoprene can be applied by machine as well as by hand.
POLYURETHANE ADHESIVE Polyurethane(P.U) is produced when a disocyanate having two isocyanine groups is reacted with a diol having two hydroxyl groups. INGREDIENTSPolyols having a molecular weight 1000.The polyols may be polyether, polyester or polybutadiene based.Diisocyanate:This is either toluene disocyanate(TDI)or methylene bis (4,4;phenyl isocyanine)MDI.Curing agent may be a short chain diol or triol for MDI and an aromatic diamine for TDI.
HOT MELT ADHESIVE These are of cent percent solid content and are free fromsolvents. The availability of a variety of polymers with abroad spectrum of properties tailored for a specific enduse, is an added advantage. Today hot melt formulationsare available for temporary as well as permanentattachment in shoe manufacture. Usually supplied to footwear industry in the form ofgranules and rods (in coils).When these adhesivesheated to high temperature, they melt rapidly into afluid, flow freely on bonding sites, wet the surfaces,quickly cool, solidify to a crystalline solid and therebyadhere to give good bond strength between the twosurfaces.
HOT MELT ADHESIVE USED IN THERMOFOLDING MACHINES AMBER COLOURED STITCHED AS IT IS NOT A PERMANENT BOND
PROPERTIESAmber coloured.Polyamide is used instead of polyester due to its flexibility, low melting point and availability in either granular, rod or block form.Toe puffs,stiifeners,backing cloths and lining material, for lamination could be precoated (either overall,or splattered)with hot melt adhesives and they attached by pressing under heated plates(hand iron, laminating press).It must be stitched as it’s not a permanent bond.
USAGE Hot melt adhesives are used in shoe upper assembly forattaching linings to uppers and edge bonding. Textilelinings with thermo cement coatings or film adhesives iskept on the upper and attached by ironing. Bondedsurface presents a clean, uniform and neat appearancewith a rapid setting. The cement is also extruded as inthe thermocementing,folding and attaching machine.
TESTS FOR ADHESIVES VISCOSITY: The object of this test is to get an idea of information regarding the age,quality,stability,solids content, molecular weight and specific gravity of the adhesive. DRYING TIME: The adhesive is applied by the brush to the surface of the material. The time at which the adhesive film develops tackiness as its starts sticking to the finger. TACK: The force required to separates two surfaces, one of which has been coated with an adhesive after they have been in contact over a specified area at a specified pressure for a specified time. Tensile testing machine is used and the results are given in pounds/sq inch required to part the test blocks.
SHELF LIFE: The viscosity of the same adhesive sample is determined periodically at the regular intervals of time,the results are compared with that of the value of a fresh sample or original shape.POT LIFE: It is determined by noting down the changes in viscosity or bond strength, but the test methods should be as agreeable between the adhesive manufacturer and the userPEEL STRENGTH: Peel strength of an adhesive in kg./cm width obtained by peeling the two surfaces and recording the adhesive strength. The objective of this test is to get an information as to the behavior of the adhesive to an andherend i.e., bond strength.
SEAM TAPES THERMOPLASTIC ADHESIVE FILM APPLIED TO SEWN SEAMS OF FABRICS TO PREVENT WATER FROM LEAKING THROUGH THE SEAMS APPLIED BY USING AIR TAPING MACHINES, LASER OR ULTRA SONIC MACHINERY. E.g. CREPE PAPER TAPE, LIGHT/MEDIUM COTTON SHEETING ETC.
strap and strippingreinforcement NYLON COATED CUT TAPE: COATED 1 OR BOTH SIDE(S) FOR STRAP AND STRIPPING APPLICATIONS NYLON CUT TAPE: COATED BOTH SIDES FOR BUCKLE HOLES IN WIDER STRAPS NON-WOVEN TAPE: COATED 1 OR 2 SIDE(S) RAW EDGE STRAPS ETC
FACING AND TRIM REINFORCEMENT COATED LIGHT COTTON DRILL TAPE: FLEXIBLE AND HIGH QUALITY COATED COMPRESSED PAPER TAPE: GOOD RESISTANCE TO COMPRESSION AND USED IN EYELET ATTACHMENT COATED NON-WOVEN POLYPROPYLENE TAPE: LIGHT WEIGHT WITH GOOD TEAR RESISTANCE AND IT HAS HIGH STRENGTH COATED NON-WOVEN POLYESTER TAPE: HIGH PERFORMANCE AND USED FOR ALL METALLIC FASTENINGS. THANK YOU.