Adhesive Bonding: Materials, Applications and Technology

Preface XV

List of Contributors XVII

1 Adhesive Bonding as a Joining Technique 1

2 The Historical Development of Adhesive Bonding 5

3 Adhesion 11

3.1 Introduction 11

3.2 Classical Adhesion Theories 14

3.2.1 Polarization Theory 17

3.2.2 Diffusion Theory 20

3.2.3 Chemical Reactions 21

3.3 Adhesion in Real Systems 24

3.3.1 Gold 25

3.3.2 Polyethylene and Polypropylene 25

3.3.3 Glass 26

3.4 New Concepts in the Field of Adhesion 26

3.5 Conclusions 28

4 Survey and Classification of Adhesives and Primers 29

4.1 Noncuring (Pressure-Sensitive) Adhesives 29

4.2 Physically Setting Adhesives 33

4.2.1 Contact Adhesives 33

4.2.2 Plastisol Adhesives 34

4.2.3 Hot-Melt Adhesives 34

4.3 Chemically Setting Adhesives 35

4.3.1 Two-Part Adhesives 35

4.3.2 Hot-Setting, One-Part Adhesives 36

4.3.3 Cold-Setting, One-Part Adhesives 36

4.3.4 Microencapsulated Adhesives 37

4.4 Primers 37

4.5 General Handling Instructions 38

5 Chemistry and Properties of Adhesives and Primers 39

5.1 Pressure-Sensitive Adhesives (PSAs) 40

5.1.1 Introduction 40

5.1.2 Chemistry of Pressure-Sensitive Adhesives 40

5.1.3 Physical Properties of Pressure-Sensitive Adhesives 43

5.1.4 Properties of Pressure-Sensitive Adhesives as a Function of Temperature 44

5.1.5 Tack 45

5.1.6 Peel Resistance 45

5.1.7 Creep 45

5.1.8 Formulations of PSAs 46

5.2 Contact Adhesives 47

5.2.1 Composition of Contact Adhesives 47

5.2.2 Properties and Fields of Application of Contact Adhesives 48

5.3 Hot Melts 49

5.3.1 Thermoplastic Hot Melts 50

5.3.2 Hot-Seal Adhesives 51

5.3.3 Plastisols 51

5.3.4 Self-Bonding Varnishes 52

5.3.5 Polyurethane-Based Reactive Hot Melts 52

5.3.6 Epoxy Resin-Based Reactive Hot Melts 52

5.3.7 Trends in Hot-Melt Technology 53

5.4 Phenolic Resin Adhesives 53

5.4.1 Chemistry of Phenolic Resins 53

5.4.2 Formulation of Phenolic Resin Adhesives 56

5.4.3 Behavior and Applications of Phenolic Resin Adhesives 57

5.5 Epoxy Resin Adhesives 58

5.5.1 Chemistry of Epoxy Resin Adhesives 58

5.5.2 Reactions of Epoxy Resins 59

5.5.3 Properties of Epoxy Resin Adhesives 60

5.5.4 Formulations of Epoxy Resin Adhesives 63

5.6 Polyurethane Adhesives 66

5.6.1 Chemistry of Polyurethanes 66

5.6.2 Raw Materials 67

5.6.3 Structure and Properties of Polyurethane Adhesives 69

5.6.4 Formulations of Polyurethane Adhesives 70

5.7 Acrylate Adhesives 71

5.7.1 Physically Setting Acrylates 71

5.7.2 Chemically Setting Acrylates 71

5.7.3 Formulations of Acrylate Adhesives 84

5.8 Silicones 85

5.8.1 One-Part Silicone Adhesives 85

5.8.2 Two-Part Silicone Adhesives 86

5.9 Natural Adhesives 88

5.9.1 Introduction 88

5.9.2 Natural Raw Materials 89

5.9.3 Modern Adhesives Based on Natural Raw Materials 91

5.9.4 Future Trends 94

5.10 Chemistry of Primers and Adhesion Promoters 94

5.10.1 Primers 95

5.10.2 Adhesion Promoters 96

5.11 Fillers 99

6 Design, Production and Quality Assurance of Adhesive Bonded Joints 101

6.1 Design and Dimensioning 101

6.1.1 Interaction of Polymer Behavior and State of Stress 101

6.1.2 Design of Adhesive Bonded Joints 103

6.1.3 Dimensioning of Adhesive Bonded Joints 104

6.2 Surface Preparation 108

6.2.1 Mechanical Surface Preparation Methods 109

6.2.2 Chemical Surface Preparation Techniques 111

6.2.3 Physical Surface Preparation Techniques 111

6.2.4 The Preconditions of Adhesion 112

6.2.5 Protection of Prepared Surfaces 114

6.3 Application of the Adhesive 115

6.3.1 Processing of Adhesives 115

6.3.2 Quality Assurance 123

7 Adhesives and Adhesive Joints: Test Methods and Properties 125

7.1 Adhesive Bulk Properties 126

7.1.1 Stress–Strain Analysis of Bulk Specimens 126

7.1.2 Determination of Tg by Dynamic Mechanical Analysis or Differential Scanning Calorimetry 127

7.1.3 Coefficient of Thermal Expansion (CTE) 128

7.1.4 Temperature Resistance by Thermogravimetry 128

7.2 Test Categories by Type of Mechanical Stress 128

7.2.1 Tensile Stress (e.g. Butt Joints) 128

7.2.2 Shear Stress (e.g. Single Lap Shear Specimen) 130

7.2.3 Cleavage (e.g. Wedge Test) 132

7.2.4 Fracture Resistance 133

7.2.5 Wedge Test 133

7.2.6 Peel Test 134

7.3 Test Categories by Duration and Load Rate 137

7.3.1 Long-Term Static Tests (e.g. Creep Experiments Under Dead Load) 137

7.3.2 Impact Tests (e.g. Impact Wedge Test to Evaluate Crash Performance) 138

7.3.3 Cyclic Loading (e.g. Fatigue Tests) 139

7.4 Assessment of Durability and Service Life of Adhesive Joints 139

7.5 Tests Related to Storage and Handling of Adhesives 143

7.5.1 Determination of Words and Phrases Relating to the Product Life 143

7.5.2 Open Time and Working Life 143

7.5.3 Extrudability 144

7.5.4 Sagging 144

7.5.5 Volatile Organic Compound (VOC) Emissions 144

7.6 Nondestructive Testing Methods 145

7.6.1 Visual Techniques 146

7.6.2 Radiographic Techniques 146

7.6.3 Magnetic, Electrical and Chemical Techniques 146

7.6.4 Mechanical Vibration 147

7.6.5 Thermal Methods 149

7.6.6 Assessment of Nondestructive Testing Methods 155

7.7 Applications of Test Methods in Structural Adhesive Bonding 156

7.7.1 Tensile Shear Strength Under Short-Term Loading 157

7.7.2 Tensile Shear Strength Under Long-Term Static and Alternating Loading 162

7.7.3 Peel Strength 164

7.7.4 Impact Behavior 165

7.7.5 Durability of Bonded Joints 166

7.7.6 Adhesive Bonding of Aluminum 168

7.7.7 Adhesive Bonding of Steel 183

7.7.8 Adhesive Bonding of Glass 188

7.7.9 Adhesive Bonding of Polymer Materials 191

7.8 Experiences and Learning from Damage Cases 191

7.8.1 Delamination of Bonded Rotor Blade Pockets 193

7.8.2 Total Separation of a Rotor Blade Profile 194

7.8.3 Bond-Line Corrosion in Wing Honeycombs 196

7.8.4 Delamination of the Outer Cover Sheet of Tail Units of Aircraft 197

7.8.5 Temperature-Induced Damage on a Tail Rotor Blade 199

7.8.6 Temperature-Induced Delamination of a Bonded Glass Fiber Patch 200

7.8.7 Incorrect Design of Bonded Filter Elements 201

7.8.8 Deficiencies of the Peel Ply Treatment 202

8 Adhesive Bonding Technology: Fields of Application 205

8.1 Introduction 205

8.2 Transportation 206

8.2.1 Aircraft Manufacture 207

8.2.2 The Automotive Industry 220

8.2.3 Bonding in Rail Vehicle Manufacture 234

8.2.4 Shipbuilding 235

8.3 Building Industry 237

8.3.1 Adhesives for the Bonding of Surfaces 237

8.3.2 Adhesive Anchors in the Building and Construction Industry 238

8.3.3 Building Reinforcement by Means of Bonded Surface Reinforcement 241

8.3.4 Structural Bonding in Structural Steel and Facade Engineering 241

8.4 Wooden Constructions 243

8.4.1 Introduction 243

8.4.2 The Structure of Wood 245

8.4.3 Consequences 246

8.4.4 Adhesive–Wood Interphase 247

8.4.5 Adhesive Systems 247

8.4.6 Adhesives Based on Renewable Resources 248

8.4.7 Synthetic Wood Adhesives 249

8.4.8 Wood Composites 251

8.4.9 The Supreme Discipline: Laminated Wood Constructions (Civil Engineering Using Wood as Building Material) 253

8.4.10 Prefabricated Elements 255

8.4.11 Prospects of Wood Constructions 257

8.5 Paper and Packaging Industry 257

8.5.1 Introduction 257

8.5.2 Manufacture of Packaging Materials 258

8.5.3 The Setting-Up and Closing of Trays and Boxes 264

8.5.4 Pallet Securing 267

8.5.5 Labeling 269

8.5.6 Cigarette Production 274

8.5.7 Manufacture of Tissue Paper Products 274

8.5.8 Graphic Products 278

8.5.9 Envelopes and Advertising Mail 286

8.5.10 Reuse and Recycling of Paper and Packages 287

8.5.11 Regulations Stipulated by Law 292

8.5.12 Perspectives 292

8.6 Small-Scale Industries and Handicraft Trades 293

8.6.1 Joining 293

8.6.2 Protecting, Splicing and Masking 301

8.6.3 Damping 304

8.6.4 Labeling, Marking and Coding 305

8.7 Electronics Industry 307

8.7.1 Thermally Conductive Adhesives 307

8.7.2 Electrically Conductive Adhesives 308

8.7.3 Underfill Materials 310

8.7.4 Functional PSA Tapes 310

8.7.5 Spacers 311

8.7.6 Labeling 311

8.8 Optical Industry 312

8.8.1 General Requirements for Adhesives in Optical Industry 312

8.8.2 Optical Adhesives for the Temporary Fixture of Optical Elements 313

8.8.3 Optical Cementing 314

8.8.4 Bonding Optical Elements to Mounts 315

8.9 Mechanical Engineering and Process Equipment Construction 316

8.9.1 Mechanical Engineering 316

8.9.2 Domestic Appliance Industry 317

8.9.3 Manufacture of Internal Combustion Engines and Transmission Manufacturing 317

8.9.4 Stainless Steel Structures 319

8.10 Textile Industry 320

8.10.1 The Early History of Fabric-Reinforced Rubber Materials 320

8.10.2 How Textile Fibers Contribute to the Living Standards of the Industrial World 321

8.10.3 General Properties of Elastomers (Rubber) 323

8.10.4 Treatment of Textiles for Rubber Reinforcement 324

8.10.5 Adhesion Mechanisms 328

8.10.6 Aging of RFL-Dipped Textiles 330

8.11 Footwear Industry 332

8.12 Road and Highway Engineering 333

8.12.1 Traffic Signs 334

8.12.2 Pavement Markings 335

8.12.3 License Plates 337

8.13 Surface Design 337

8.13.1 Surface Design and Surface Protection 337

8.13.2 Fleet Graphics 338

8.13.3 Public Transport Advertising 338

8.13.4 Building and Floor Graphics 340

8.14 Tamper-Indicating Labels 341

8.15 Medical Sector 343

8.15.1 Medical Devices with Short-Term, Superficial Body Contact 343

8.15.2 Medical Devices with Several (up to 30) Days Body Contact 343

8.15.3 Medical Devices with Long-Term (Over 30 Days) Body Contact 344

8.16 Adhesion in Nature 346

8.16.1 Design Principles of Biological Attachment Devices 346

8.16.2 Gluing Under Water 347

8.16.3 Adhesion in Terrestrial Insects 354

8.16.4 Adhesion in Plants 355

8.16.5 Surface-Replicating Mechanism Based on Growth 356

8.17 Little-Known Applications 356

8.17.1 Foils for the Rotors of Wind Turbines 356

8.17.2 Adhesive Elastomer Composites 358

8.17.3 Light Bulbs 359

8.17.4 Bonding in Art, Jewelry Making and Archeology 361

8.17.5 Removable Adhesive Joints 365

9 Perspectives 371

9.1 Economic Trends 371

9.2 Technical Trends 371

Appendix 375

References 393

Index 403