Tài liệu Ktf_3_klebstoffarten_final stbo

Adhesive Manufacturing Processes Chapter 3: Types of Adhesives Univ.-Prof. Dr.-Ing. Prof. h.c. Stefan Böhm Department for Cutting and Joining Manufacturing Processes (tff) University of Kassel, Germany Quelle: Wikipedia Definitions  Adhesive (DIN EN 923) is a non-metallic material that functions as a bonding material via surface adhesion (adhesion) and internal strength (cohesion).  Main Purpose: Transmission of force  Sealant (DIN EN 26 927) is a material that seals a joint by bonding to the edges of the joint.  Main Purpose: Sealing of surfaces to prevent the discharge of liquid Every adhesive can seal, but every sealant can also bond! 2 Agenda  Introduction  Chemically Reacting Adhesives  Physically Bonding Adhesives  Examplary Selection of Adhesives 3 Adhesives – Possible Classifications  There are many possibilities to classify adhesives, depending on…  Specific Application  Geometry of the Bond  Chemical Basis of the Adhesive  Strength Class  Outward Form  Number of Components within the Adhesive  Setting Mechanism 4 Specific Applications Bonding of Metals Phenolic resin adhesives, acrylates, epoxy resin adhesives, polyurethane adhesives, polyester resin adhesives Bonding of Synthetic Materials Solvent-based adhesives, acrylates, epoxy resin adhesives Bonding of Glass Bonding of Ceramics Bonding of Wood Bonding of Leather Source: Kleben, Habenicht, Springer Verlag Polyurethane adhesives, silicone adhesives, epoxy resin adhesives, cyanacrylate Phenolic resin adhesives, epoxy resin adhesives Polyvinyl acetate adhesives (PVAC) Rubber adhesives 5 Geometry of the Bond Rotationally Symmetric  Screwing  Pipe- Connections  Shaft- Connections Source: Kleben, Habenicht, Springer Verlag Axially Symmetric       Level Rectangular Overlapping (level) Corner Joint Edgefolding Adhesion Butt-Joints Asymmetric  Shaft – Level  Level - Level 6 Chemical Basis Organic Adhesives Inorganic Adhesives Natural Basis Artificial Basis Protein, Carbohydrates, Natural Resins Acrylates, Polyurethanes, Epoxies Metal Oxides, Silicates, Borates, Phosphates Silicones (Compound with organic and inorganic characteristics) Source: Kleben, Habenicht, Springer Verlag 7 Strength Classes  Structural Bonds Strength (i.e. 1-C-Epoxy Resin)  Semi-Structural Bonds (i.e. 2-C-PUR)  Fixation Bonds (i.e. Fast-Setting Adhesive)  Elastic Bonds (i.e. 1-C-PUR)  Sealing Bonds (i.e. Acrylate-Sealant) Source: TC Kleben Elasticity 8 Outward Forms Fluid Adhesives Adhesive Putty Solid Adhesives Reaction Adhesives, Adhesive Varnish, Pastes Larch Resin, Canada Balsam Hotmelt Adhesives, Powder Adhesives, Adhesive Films i.e.: Metalworking industry i.e: Visual industry i.e.: Furniture Industry Source: Kleben, Habenicht, Springer Verlag 9 Number of Components within the Adhesives 1 Component (1C) - Epoxy Resins Polyurethanes - Acrylates - Silicones Source: Kleben, Habenicht, Springer Verlag 2 Components (2C) 3 Components (3C) - Epoxy Resins Polyurethanes - Acrylates - Silicones - Acrylates - Epoxy Resins 10 Setting Mechanisms Chemically Reacting Physically Bonding Cold Setting Hot Setting Polymerisation Adhesives Polyaddition Adhesives Polycondensation Adhesive Source: Kleben, Habenicht, Springer Verlag Hotmelt Adhesives Solvent-Based Adhesives Plastisols 11 Criteria for the Classification of the Setting Mechanism  Condition of the molecules at the beginning of the bonding process Reaction Adhesives Setting Adhesives Polymers are formed out of monomers Polymers are already complete Small, reactive molecules (monomers) are made into long, partly interlinked molecules (polymers) through a chemical reaction.  chemically hardening Source: Kleben, Habenicht, Springer Verlag Using either solvents or high temperatures the polymers are made wettable. When the solvent evaporates or the adhesive cools down, it hardens.  physically bonding 12 Adhesives - Overview Chemically Hardening Physically Bonding Polyaddition Epoxy Resins Polyurethanes Through Solidification Hotmelt Adhesives Polycondensation Silicones MS-Polymers Phenolic Resins Polyester Resins Through Evaporisation Solvent-Based Adhesives Dispersions Contact Adhesives Polymerisation Cyanacrylates Methyl Methacrylates Anaerobic Adhesives Radiation Curable Adhesives Source: Kleben, Habenicht, Springer Verlag Permanently Adhesive Pressure Sensitive Adhesive Butyle Rubbers Through Gelling Plastisols 13 Agenda  Introduction  Chemically Reacting Adhesives ● Polyaddition Adhesives ● Polymerisation Adhesives ● Polycondensation Adhesives  Physically Bonding Adhesives  Examplary Selection of Adhesives 14 2C-Adhesives in General  Two-Component-Adhesives  Two adhesive monomers are used that are spatially apart  One of the monomers contains resin monomers, whilst the other contains hardeners  Need to be brought to react by mixing them  The so created polymer/resin is the cured adesive Processing  Mixing Ratio  Rate of Dilution  Pot Life Source: Kleben, Habenicht, Springer Verlag 15 Pot Life – Processing Time of 2C-Adhesives The time in which the reactive adhesive has to be used after all components have been mixed  Means the time in which the completed adhesive mixture can be used, i.e. the processing time at room temperature  Begins with the first encounter of the adhesive monomers  Ends when the curing process has gone so far that hardness and viscosity have increased measurably and further processing is no longer possible Source: Kleben, Habenicht, Springer Verlag 16 2C-Adhesives in General  Pot life is dependent on the surrounding temperature and the quantity Time [min] Example according to data sheet: 10 min at 20°C 20 10 5 0 Source: Kleben, Habenicht, Springer Verlag 10 20 Rule: An increase in temperature of 10°C reduces the pot life to half 40 30 Temperature [°C] 17 Curing of 2C-Adhesives Curing time Period of time that an adhesive needs to reach at least handling strength or, at the latest, its final strength. Festigkeit 100% Gelpunkt Gel point 0% Handling Strength Pot life Source: Kleben, Habenicht, Springer Verlag Time Final Strength 18 Influence of the Temperature on Chemical Reactions  Influence of the temperature on the speed of reaction during the curing process of reactive adhesives Reaktionsgeschwindigkeit The higher the temperature, the quicker the curing process will be The lower the temperature, the slower the curing process will be Rule: An increase in temperature of 10°C reduces the pot life to half and therefor doubles the speed of reaction Temperature Source: Kleben, Habenicht, Springer Verlag 19 Types of Adhesives Chemically Curing Adhesives Polyaddition Polymerisation Epoxy Resins Cyanacrylates Silicones Polyurethanes Methyl Methacrylates MS- Polymeres Anaerobic Adhesives Phenolic Resins Radiation Curable Adhesives Polycondensation Polyester Resins 20