Understand the science of joining wood with this comprehensive guide
Long seen as an old-fashioned material with narrowing modern applications, wood has seen increased popularity as a material in building and manufacturing in recent years. This has been driven by the need for sustainable resources and environmentally friendly materials. As a result of increased emphasis on wood, however, there is a corresponding need to understand the wood adhesives, the crucial materials in wood-based manufacture and craftsmanship.
Adhesives and Finishes for Wood meets this need with a comprehensive but accessible introduction to the chemistry and applications of wood adhesives. Its easy-to-follow presentation nonetheless presents wood adhesives and finishes in significant detail. Ideal for readers without considerable preexisting knowledge in chemistry, this book includes everything the reader needs to understand and apply wood adhesives in their work or industry.
Adhesives and Finishes for Wood readers will also find: - Coverage ranging from the fundamentals of wood adhesive polymer chemistry to the properties of specific wood structures and resins - A presentation suitable for both academic students and wood manufacture professionals - An author with decades of experience in both academia and industry
Adhesives and Finishes for Wood is a useful reference for advanced students and professionals in industries or manufacturing disciplines that incorporate wood, as well as for chemists, materials scientists, vocational school instructors, and more.
Table of Contents
Preface xix
Author Biography xxi
1 Introduction to Polymers, Wood Adhesives, and Wood Finishes 1
1.1 Good Wood Adhesives Must Be Optimum Polymers with Optimum Secondary Forces 1
1.2 Polymeric Materials 2
1.3 Synthetic Polymer Preparation Methods 2
1.4 Typical Synthetic Polymer Materials 3
1.5 Typical Natural Polymers 8
1.6 Summary 10
References 11
2 Principles of Polymer Chemistry for Wood Adhesives and Finishes 12
2.1 Degree of Polymerization and Molecular Weight 12
2.2 Properties of Polymer Solutions or Suspensions 13
2.3 Polymer Solids Level and Specific Gravity of Polymer Solutions 18
2.4 pH of Polymer Solutions and Buffers 18
2.5 Solid Properties of Polymer Materials 20
References 22
3 Thermosetting and Thermoplastic Wood Adhesives and Practices 23
3.1 Selection Criteria of Wood Adhesives 23
3.2 High Temperature-Curing Thermosetting Adhesives and Curing Conditions 24
3.3 Room Temperature-curing Thermosetting Wood Adhesives and Processes 25
3.4 Room Temperature-curing Thermoplastic Wood Adhesives 25
3.5 Adhesive Application Methods and Loading Rates and Costs 26
3.6 Adhesive Curing by Hot Presses and Other Heating Methods 26
3.7 Evaluation of Adhesive Bonds 28
3.8 Summary 28
References 28
4 Principles of the Curing of Thermosetting and Thermoplastic Wood Adhesives 29
4.1 Principles of Curing of Thermosetting Adhesive Resins at Elevated Temperatures 29
4.2 Relationship of Temperature and Moisture Content in Hot-Pressing of Wood Composite Mats 33
4.3 Curing of Thermosetting Adhesives at Room Temperature 35
4.4 Curing of Thermoplastic Emulsion Adhesives 36
4.5 Volume Contractions of Adhesive Layers upon Curing 37
4.6 Thermal and Moisture Expansion/Contraction of Adhesive Layers 38
4.7 Summary 38
References 39
5 UF and MUF Wood Adhesive Resins (Manufacturing and Resin Chemistry) 40
5.1 Raw Materials of UF Resins 40
5.2 Urea-Formaldehyde (UF) Resins 42
5.3 Chemistry Occurring in UF Resin Synthesis 46
5.4 Polymer Chain Branching in UF Resins 50
5.5 Other Reactions Occurring in UF Resin Synthesis 52
5.6 F/U1 Mole Ratio Effects in the Polymerization Step 53
5.7 Final F/U Mole Ratios and Formaldehyde Emission Problem 54
5.8 Physical and Chemical Tests and Properties of Industrial UF Resins 55
5.9 Resin Changes Occurring After Manufacture of UF Resins 58
5.10 Bond Performances and Durability Tests of UF Resins in Industry 60
5.11 UF Resins vs. Various Operating Parameters in PB, MDF, and Hardwood Plywood Industry 61
5.12 Other UF Resin Synthesis Procedures 62
5.13 Polymeric Chemical Structures of UF Resins 63
5.14 Melamine-Urea-Formaldehyde (MUF) Resins 63
5.15 Urea-Melamine-Formaldehyde (UMF) Resins 66
5.16 Summary 69
References 69
6 Urea-Formaldehyde and MUF/UMF Wood Adhesive Resins (Curing) 72
6.1 Typical Latent/External Catalysts Based on Ammonium Salts for UF Resins 72
6.2 Organic Tertiary Amine Salts of Strong Acids and Other Catalysts 73
6.3 Catalyzation of UF Resins by Wood Acids 74
6.4 Buffering of Acidic Catalysts 77
6.5 Thermosetting Curing Reactions, Cured Resin Structures, and Formaldehyde Emission Problem 78
6.6 Control of the Curing Speeds of UF Resins 81
6.7 Side-Reactions Occurring in the Curing of UF Resins 81
6.8 Phenomenological Changes of UF Resins in Curing 82
6.9 Chemical Curing Mechanisms, F/U Mole Ratio, and Cured Resin Structure 84
6.10 Composition of Cured UF Resins 85
6.11 Uses of UF Resins 86
6.12 Properties of UF Resin-Bonded Wood Composite Boards 86
6.13 Formaldehyde Emission Mechanisms, Mole Ratios, and Board Strength Properties 87
6.14 Various Methods Proposed/Practiced for Reducing the Formaldehyde Emissions of Boards 88
6.15 Curing of Melamine-Urea-Formaldehyde (MUF) Resins 89
6.16 Curing of Urea-Melamine-Formaldehyde (UMF) Resins 90
6.17 Cost Increases Estimated for Boards with Very Low Formaldehyde Emission Values 91
6.18 Summary 92
References 92
7 Particleboard, MDF, and Hardwood Plywood Bonding with UF Resin Binders 94
7.1 Particleboard 94
7.2 Medium Density Fiberboard (MDF) Bonded with UF Resins 102
7.3 Hardwood Plywood Bonding with UF Resin Adhesives 109
7.4 Paraffin Wax and Uses in Wood Composites 112
7.5 Effects of UF Resins’ Curing Catalysts on Tool Wear in Machining of Boards - An Example of Laboratory PB Manufacturing and Testing 115
7.6 Summary 120
References 120
8 PF Novolac Wood Adhesive Resins (Manufacturing and Chemistry) 122
8.1 Raw Materials of PF Resins 122
8.2 Reaction Chemistry of Phenol 123
8.3 Synthesis and Chemistry of Novolac Phenol-Formaldehyde (PF) Resins 124
8.4 Compounding and Curing of Novolac PF Resins 129
8.5 Curing Speed and Testing Methods of Molding Compounds of PF Novolac Resins 130
8.6 Wood Adhesive Uses of Novolac PF Resins 132
8.7 Summary 133
References 134
9 PF Resole Wood Adhesive Resins (Manufacturing and Chemistry) 136
9.1 Alkaline PF Resole Wood Adhesive Resins 136
9.2 Synthesis Chemistry and Manufacturing Practices of Alkaline PF Resole Resins 136
9.3 Typical Synthesis Procedures of Alkaline PF Resole Resins for Various Uses 140
9.4 Properties and Polymer Structures of Alkaline PF Resole Resins and Measurements 143
9.5 Resin Characteristics and Uses of Various PF Resole Resins 147
9.6 Molecular Weights (Sizes) of Alkaline PF Resole Resins and Wood Cell Wall Penetration 148
9.7 Powder PF Resole Resin Manufacturing by Spray-drying 149
9.8 Curing of Alkaline PF Resole Resins 150
9.9 Good Wood Adhesion and Exterior Durability of PF Resin Adhesives 158
9.10 Formaldehyde Emission Problem of PF Resin-bonded Products 159
9.11 Various Binder Uses of PF Resins in the US Wood Products Industry 159
9.12 Acid-curing PF and PMF Resole Resin and Dispersion Wood Adhesives 162
9.13 Summary 163
References 163
10 PRF Novolac Wood Adhesive Resins and Lumber Lamination 166
10.1 Manufacturing and Chemistry of PRF Resins 167
10.2 PRF and RF Resin Adhesives Currently Available in Industry 172
10.3 Hardeners for PRF Resin Adhesives 174
10.4 Mixing of a PRF Resin and Hardener, Pot-Lives, Working Life, and Assembly Time 175
10.5 Applying and Curing of PRF Adhesives in Wood Lamination 176
10.6 Curing Chemistry of PRF Resin Adhesives and Industry Practices 179
10.7 Wood Lamination Industry 179
10.8 Recent Developments in PRF Resin Adhesives 182
10.9 Laminating Wood Adhesives Based on Other Resorcinolic Materials 184
10.10 Advanced Reading Materials on Resorcinol-Formaldehyde (RF) Resins 185
10.11 Summary 191
References 191
11 Softwood Plywood Adhesives and Manufacturing Technology 194
11.1 Softwood Plywood Manufacturing Technology 194
11.2 PF Resole Resins for Bonding of Softwood Plywood 195
11.3 Veneer, Veneer Drying, and Adhesion Problems 196
11.4 Bond Performance Characteristics of Softwood Plywood Adhesives 197
11.5 Softwood Plywood Adhesive Mixing Procedure 197
11.6 Softwood Plywood Adhesive Formulation and Characteristics 198
11.7 Open and Closed Assembly Times 204
11.8 Pre-pressing of Softwood Veneer Assembly 204
11.9 Hot-Pressing Parameters of Softwood Plywood 204
11.10 Laminated Veneer Lumber (LVL) 207
11.11 Parallel (Veneer) Strand Lumber (PSL) 207
11.12 New Developments in the Softwood Plywood Adhesive Technology 208
11.13 Phenolic Components Present in PF Resin-Bonded Softwood Plywood 209
11.14 Softwood Plywood Manufacturing Industry 209
11.15 Plywood Adhesive Fillers Made from Hydrolysis Residues of Municipal Newsprint Wastes 210
11.16 Conclusion 214
11.17 Summary 214
References 214
12 Isocyanate Wood Adhesive Resins 217
12.1 Chemical Compositions of Isocyanate Wood Adhesive Resins 217
12.2 Reactivity, Polymerization, and Curing Reactions of Isocyanate Resins 218
12.3 Mat Moisture Levels in Using pMDI Resins for OSB Bonding 223
12.4 Bond Properties and Uses of pMDI Resins as OSB Binders 224
12.5 pMDI Resins Used in Bonding of Other Wood Composite Products 226
12.6 Summary 227
References 227
13 OSB Manufacturing with PF and Isocyanate Wood Adhesive Resins 229
13.1 Oriented Strand Board (OSB) Manufacturing Processes 229
13.2 OSB Bonded with PF Resins with Various Levels of Urea Added at the End of Resin Synthesis 240
13.3 Summary 246
References 247
14 Polyvinyl Acetate (PVAc) Emulsion Wood Adhesives 249
14.1 Polyvinyl Acetate (PVAc) Emulsion Wood Adhesive Resins 249
14.2 Summary 253
References 254
15 Troubleshooting in Wood Bonding with PVAc Resin Adhesives 255
15.1 Effects of Moisture Content of Wood 255
15.2 Troubleshooting Methods in Various Gluing Operations 259
Reference 262
16 Hot-melt and Other Specialty Wood Adhesives 263
16.1 Introduction to Hot-melt Adhesives 263
16.2 Requirements For Hot-melt Adhesives 263
16.3 Materials Used for Hot-melt Wood Adhesive Formulations 265
16.4 Advantages and Disadvantages of Hot-melt Adhesives 266
16.5 Thermosetting Hot-melt Adhesives - Recent Development 267
16.6 Key Variables in Hot-melt Edge-banding Operation 268
16.7 Other Specialty Wood Adhesives 269
References 273
17 Casein, Soybean Flour, Animal Blood, and Lignin Wood Adhesives 275
17.1 Casein Wood Adhesives 275
17.2 Animal Protein-Based Wood Adhesive 276
17.3 Soybean Meal and Soybean Protein Wood Adhesives 276
17.4 Animal Blood-based Wood Adhesives 278
17.5 Various Lignins and Uses in Wood Adhesives 278
References 281
18 Theory and Practices of Adhesive Bonding for Wood 283
18.1 Formation of Interphase in Wood Adhesive Bonds and Failure Modes 283
18.2 Wettability of Solid Surface, Contact Angle, and Surface/Interface Tensions 287
18.3 Work of Adhesion 291
References 291
19 Physical and Chemical Mechanisms of Adhesive Bonding for Wood 292
19.1 Adsorption (Secondary Bond Forces) Theory of Adhesion 292
19.2 Mechanical Interlocking Theory of Adhesion 296
19.3 Diffusion Theory of Adhesion 297
19.4 Primary Chemical Bond (Covalent Bond) Theory 298
19.5 Summary of Adhesion Mechanisms 299
19.6 Glueline Layer Thickness and Bond Strengths 299
19.7 Summary 301
References 301
20 Evaluation of Wood Adhesive Bonds, Quality Control, and Bond Durability 302
20.1 Mechanical Testing Modes and Methods for Measuring the Adhesive Bond Strength 302
20.2 Quality Control, Certification Tests, and Adhesive Bond Durability 309
20.3 Comparison of Various Wood Adhesive Bonds by Accelerated Aging or Exterior Exposure Tests 313
20.4 Nondestructive Testing of Wood and Wood Adhesive Bonds 315
20.5 In-situ Adhesion Testing 315
References 316
21 Introduction to Coatings Technology for Wood 317
21.1 Three Components of Coatings 317
21.2 Pigment Volume Concentration (PVC) 317
21.3 Various Kinds of Vehicle Polymers 319
References 328
22 Introduction to Coatings Technology for Wood. II 329
22.1 Pigments and Fillers 329
22.2 Manufacturing and Kinds of Pigments and Fillers 329
22.3 Color Control Methods 329
22.4 Color Scales - Hunter L, a, b, and CIE 1976 L*a*b* (CIELAB) Color Scales 331
22.5 Carriers of Coatings 332
22.6 Additives to Coatings 332
22.7 Manufacturing Procedures of Coatings 332
22.8 Film Formation Mechanisms 333
22.9 Water-Borne Coatings and Coatings for Less VOC Emissions 334
22.10 Exterior Coatings for Wood 336
22.11 Summary 337
References 338
23 Industrial Coating Application Processes 339
23.1 Application Methods of Coatings 339
23.2 Sanding Processes 342
23.3 Sanding Abrasives, Construction, and Flexing 344
23.4 Typical Furniture Finishing Procedures and Materials 344
23.5 Flat Line Finishing Procedures of Wood Composite Boards for Furniture Production 346
23.6 Kitchen Cabinet Finishing Procedures 347
23.7 Hardwood Plywood Panel Prefinishing 348
23.8 Hardboard Panel Finishing Procedures 349
23.9 Summary 350
References 350
24 Advanced Reading Materials on UF Wood Adhesive Resins 351
24.1 Introduction to the 13C NMR Spectroscopic Analysis Method 351
24.2 Introduction to 13C NMR Analysis Methods of UF and UMF Wood Adhesive Resins 356
24.3 13C NMR Analysis Results of Reaction Intermediates Taken in UF Resin Syntheses 360
24.4 13C NMR Analysis Results of Reaction Intermediates Taken in UF Resin Syntheses with a Higher Power Instrument 366
24.5 Chemical Changes Occurring in UF Resins on heat/stirring and Room-temperature Storage Treatments by 13C NMR and Formaldehyde Emission Tests of Particleboard 374
24.6 Effects of Mild Heating/Stirring Treatments on UF Resins Synthesized with Different F/U1 Mole Ratios by 13C NMR 382
24.7 Effects of Room-temperature Storage Treatments on UF Resins Synthesized with Various F/U1 Mole Ratios by 13C NMR and Formaldehyde Emission Tests of Particleboard 388
24.8 Effects of Mild Heat/Stirring and Room-temperature Storage Treatments of UF Resins Synthesized with Various F/U1 Mole Ratios by 13C NMR and Formaldehyde Emission Tests 397
References 418
25 Advanced Reading Materials on UMF Resins Modified with 6-12% Melamine 420
25.1 Introduction and Synthesis and Analysis Results of UF and UMF Resins 420
25.2 DMA Curing Properties of UF and UMF Resins 432
25.3 Bond Performance of UMF Resins as Particleboard Binders 443
References 445
26 Advanced Reading Materials on UMF Resins Modified with 2.5% and 5.0% Melamine 447
26.1 UMF Resins Synthesized with 2.5% and 5.0% Melamine Levels 447
26.2 UMF Resins Synthesized by Adding Melamine at Different Points 456
References 467
27 Advanced Reading Materials on Diethylene Tricarbamide-Formaldehyde Resins 468
27.1 Introduction 468
27.2 A Higher Functionality Urea Analogue - Diethylene Tricarbamide 469
27.3 Chemical and Physical Properties of Diethylene Tricarbamide 469
27.4 An Efficient Synthesis Method of Diethylene Tricarbamide 470
27.5 Synthesis Chemistry and Procedure and Properties of D-formaldehyde (DF) and Copolymer Resins 470
27.6 Synthesis Formulations of DF Resins vs. UF Resins 471
27.7 Room Temperature Storage Properties of DF and Copolymer Resins 472
27.8 Pot-lives and Curing Characteristics of DF and Copolymer Resins 472
27.9 Preparation of Laboratory Particleboards and Testing 473
27.10 Test Results of Prepared Laboratory Particleboards 473
27.11 Summary 475
References 475
28 Advanced Reading Materials on PF Resole Wood Adhesive Resins 476
28.1 Chemical Structures of PF Resole and Novolac Resins by 13C NMR Spectroscopy 476
28.2 Reaction Rates and Structures of a PF Resole Resin Synthesized at 70∘C 482
28.3 Polymer Structures of a PF Resole Resin Synthesized at 102∘C vs. a Commercial Resin 490
28.4 Polymer Structures of High Molecular Weight Fractions of a PF Resole Resin 500
28.5 Polymer Structures of Cured PF Resole Resins by Solid-state 13C NMR 508
References 518
Index 521
