Corrugating Medium Reference
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Corrugating Medium Reference Its Influence on Box Plant Operations and Combined Board Properties and Package Performance Project 3808 Report To The Technical Division of the Containerboard and Kraft Paper Group of The American Forest and Paper Association May 2, 1994 Institute of Paper Science and Technology Atlanta, Georgia By Joseph J. Batelka 1993 Acknowledgment The author wishes to express his sincere appreciation to the Containerboard and Kraft Paper Group of the American Forest & Paper Association for providing the funding for this undertaking, and to the Institute of Paper Science and Technology for providing the logistical support needed to complete this project. iii Table of Contents Corrugating Medium ii IPST Mission Statement ii IPST Accreditation Statement ii IPST EEO Statement ii IPST Notice and Disclaimer Statement iii Acknowledgement v Table of Contents vii List of Figures and Tables Introduction Chapter I Introduction . .. ... .. .. ... .. .. I Fluting Chapter 2 Flute Forming Theory .................................................... 3 Chapter 3 High/Low Flutes ....................................................... 9 Chapter 4 Fractured Flutes ...................................................... 23 Chapter 5 Medium Strength Loss By Fluting ........................................... 35 Bonding Chapter 6 Bonding Theory ...................................................... 53 Chapter 7 Single-Face Bonding ................................................... 67 Chapter 8 Double-Face Bonding ................................................... 81 Combined Board Chapter 9 Combined Board Issues .................................................. 93 v Chapter 10 Flexural Stiffness . ................................................... 95 Chapter 11 Edge Crush Test . ........................................ 109 Chapter 12 Flat Crush Test .................................... 135 Package Performance Chapter 13 Package Performance Issues ................................... 157 Chapter 14 Package Compressive Strength ................................... 161 Chapter 15 Package Rough Handling . ..................................... 179 Reference Chronological Bibliography .................................. .... 193 Author Index ....................................................... 203 Subject Index .................................... 205 vi List of Tables and Figures Chapter 2 Flute Forming Theory Fig. 2.1. Schematic Diagram of Forces Acting During Flute Forming in the Single-Facer Operation ......... 4 Table 2.1. Relative Tensile Forces Generated in the Medium Web by the Various Mechanical Elements in the Single-Facer Operation .............................................. 5 Fig. 2.2. Compression and Permanent Caliper Loss of Medium During the Flute Forming Operation ......... 6 Fig. 2.3. Effect of the Medium Web Tension on the Medium Draw Factor ......................... 7 Chapter 3 High/Low Flutes Fig. 3.1. Regression Equation Relating the High/Low Flute Defect to Combined Board Edge Crush Test ...... 10 Table 3.1. Vibration Amplitudes in Single-Facer ........................................ 11 Fig. 3.2. Effect of Single-Facer Process Variables on the Springback of Fluted Medium .... ............ 12 Fig. 3.3. Effect of Single-Facer Process Variables on the High/Low Flute Defect .................... 13 Fig. 3.4. Effect of Single-Facer Process Variables on the High/Low Flute Defect ................... 14 Fig. 3.5. Effect of Single-Facer Process Variables on the High/Low Flute Defect ................... 15 Table 3.2. Major Variables Affecting the High/Low Flute Defect .............................. 16 Fig. 3.6. Effect of Corrugator Speed and Medium Basis Weight on the High/Low Flute Defect ........... 17 Fig. 3.7. Regression Equation Relating Medium Friction and Formation to the High/Low Flute Defect ....... 18 Fig. 3.8. Effect of Corrugator Speed and Medium Basis Weight on the High/Low Flute Defect ........... 19 Fig. 3.9. Effect of Medium Moisture and Corrugating Roll Temperature on Springback of Fluted Medium ... 20 Table 3.3. Effect of Lubricant on Friction and the High/Low Flute Defect ......................... 21 Fig. 3.10. Effect of Refining and Wet Pressing on Corrugating Medium Properties ................... 22 Chapter 4 Fractured Flutes Fig. 4.1. Effect of Flute Fracture on Flat Crush and Edge Crush .............................. 24 Fig. 4.2. Effect of Medium Web Tension on the Flute Fracture Defect .......................... 25 Fig. 4.3. Effect of Single-Facer Process Variables on the Flute Fracture Defect ..................... 27 Fig. 4.4. Effect of Single-Facer Process Variables on the Flute Fracture Defect ..................... 28 Fig. 4.5. Regression Equation Relating Medium Properties to the Flute Fracture Defect ................ 29 Fig. 4.6. Theoretical Model Relating Single-Facer Process Variables and Medium Properties to the Flute Fracture Defect . ................................................ 30 Fig. 4.7. Verification of Theoretical Model in Fig. 4.6. ................................... 31 Table 4.1. Summary of Major Process and Material Factors Affecting the Flute Fracture Defect ............ 26 Table 4.2. Effect of Lubricant on Friction and the Flute Fracture Defect ........................... 32 Fig. 4.8. Effect of Medium In-Feed Rolls on the Flute Fracture Defect .......................... 33 Chapter 5 Medium Strength Loss By Fluting Fig. 5.1. Compression and Permanent Caliper Loss of Medium During the Flute Forming Operation ...... .. 36 vii Table 5.1. Effect of Heat Treatment on the Physical Properties of Corrugating Medium .... ............. 37 Fig. 5.2. Effect of Temperature and Moisture Content on the Tensile Strength and Tensile Stretch of Corrugating M edium .................................................. 38 Fig. 5.3. Effect of Single-Facer Process Variables on the Springback of Fluted Medium ................ 39 Fig. 5.4. Effect of Medium Moisture and Corrugating Roll Temperature on Medium Springback of Fluted Medium ..................................................... 40 Fig. 5.5. Effect of Medium Web Moisture Content During Fluting on the Fluted Medium Tensile Strength .... 41 Fig. 5.6. Effect of Corrugating Roll Temperature on Medium Concora Strength .................... 42 Fig. 5.7. Regression Equation Relating Corrugating Conditions and Medium Properties to Flat Crush ....... 43 Fig. 5.8. Effect of Medium Properties on Medium Crush Strength Retention After Fluting .............. 45 Fig. 5.9. Regression Equation Relating Medium Elastic Properties to the CD Crush Strength Retention After Fluting ....................................................... 46 Fig. 5.10. Relationship Between MD STFI Compression of Fluted Medium and Flat Crush .............. 47 Fig. 5.11. Relationship Between Fluted Medium Springback and Medium Concora Strength .............. 48 Fig. 5.12. Effect of Refining and Wet Pressing on Flat Crush Strength Retention After Fluting ............ 49 Fig. 5.13. Effect of Refining and Wet Pressing on Edge Crush Strength Retention After Fluting ............ 50 Table 5.2. Major Corrugating Conditions and Medium Properties Affecting Medium Strength Retention A fter Fluting ....................................................... 51 Chapter 6 Bonding Theory Table 6.1. Seven Major Steps in the Corrugator Bonding Process .............................. 53 Fig. 6.1. Energy Requirements of the Various Bond Setting Stages of the Corrugator Starch Adhesive ....... 55 Fig. 6.2. Corrugator Starch Adhesive Viscosity Changes During the Bond Setting Process .............. 56 Fig. 6.3. Failure Modes of Corrugator Green-Bonds and Cured Bonds .......................... 58 Fig. 6.4. Effect of Paper Moisture Content on the Elapsed Time to Achieve a Fiber Tear Bond Failure Mode ... 59 Fig. 6.5. Relationship Between the Single-Facer Cured Bond Failure Mode and the Pin Adhesion Strength for Commercially Produced Board ............................................ 60 Fig. 6.6. Effect of Medium Properties on the Transfer of Adhesive to the Flute Tip from the Glue Applicator Roll ..................................................... 62 Fig. 6.7. Effect of Medium Properties on the Penetration of Starch Adhesive into the Corrugating Medium .... 63 Fig. 6.8. Permanent Transverse Compression of Medium Due to the Corrugating Roll Pressure ........... 64 Fig. 6.9. Effect of Permanent Transverse Compression of the Medium on Adhesive Transfer to the Flute Tip and on the Penetration of Starch Adhesive into the Medium ........................ 65 Table 6.2. Starch Adhesive Penetration into the Medium of Commercially Produced Corrugated Board ....... 66 Chapter 7 Single-Face Bonding Fig. 7.1. Single-Facer Green-Bond Development Curve ................................... 69 Fig. 7.2. Effect of the Medium Preconditioning Level on the Single-Facer Green-Bond Development Rate .... 70 Fig. 7.3. Effect of Corrugating Variables on the Single-Facer Green-Bond Development Rate ............ 71 Fig. 7.4. Relative Effectiveness of Corrugating Variables on Changing the Single-Facer Green-Bond Developm ent Rate ................................................... 72 Fig. 7.5. Effect of Corrugator Process Variables and Medium Properties on the Single-Facer Cured Bond Pin Adhesion Strength ............................................. 73 Fig. 7.6. Effect of Single-Facer Speed on the Cured Bond Pin Adhesion Strength .................... 74 Fig. 7.7. Effect of Single-Facer Speed and Medium Basis Weight on the Cured Bond