Novel Isocyanate-Reactive Adhesives for Structural Wood Based Composites (LVL) ITP Forest Products Peer Review April 5-6, 2006

Transcription

1 Novel Isocyanate-Reactive Adhesives for Structural Wood Based Composites (LVL) ITP Forest Products Peer Review April 5-6, 2006

2 Outline I. General Project Information II. Delamination Tests III. Mechanical Properties of LVL IV. Rheological Characteristics V. Outlook

3 Superior Project Objectives Superior Project Objectives Development of a novel adhesive for cold-press production of Laminated Veneer Lumber (LVL) Development of new Adhesive technology: 100% organic, isocyanate-reactive polyurethane Reactive latex crosslinked with polyisocyanate Adhesive Application in EWP with focus on LVL a) Structural applications Headers I-Beams, support beams Rafters b) Non-structural applications Furniture Window and door frames

4 Technology Description I Typical components of a isocyante-reactive polyurethane adhesive NCO O O HN C O R O C NH H O R O H n NCO OCN 4,4'-MDI NCO H or n H OCN HN O C NH R NH n O C NH H N R N H n OCN II Adhesive chemistry of a latex-polyurethane blend part 1 Hydroxyl functional latex, resembling a "white glue" HO OH OH HO OH OCN ~ 1 μm part 2 CH 2 CH 2 NCO pmdi n = 1-8 NCO

5 Typical Structural Application of LVL

6 Energy Savings and Related Benefits Use of veneer with higher moisture content Drastically reduced drying energy input Tendency of veneer over-drying and related surface energy reduction is minimized (wettability) Improved product durability Elimination of the hot-pressing process Reduced energy consumption No wood plastification => increased dimensional stability and strength properties VOC reduction Work safety improvement due to flatter veneer Transparent bondline

7 Technical Hurdles Project: Pass ASTM D delamination test Mechanical strength requirements Industrial Application: New technology requires adjustments in adhesive handling and application Modified veneer drying procedure Totally new pressing process is required

8 Outline I. General Project Information II. Delamination Tests III. Mechanical Properties of LVL IV. Rheological Characteristics V. Outlook

9 Adhesive Development Delamination Test Results I 100 Delamination [%] HB222 VL297A DL2119 Pass HB222 VL297A DL2119 Pass Southern Yellow Pine Yellow Poplar

10 Adhesive Development Delamination Test Results II Delamination [%] HB222 VN3041 Pass HB222 VN3041 Pass Southern Yellow Pine Yellow Poplar

11 Outline I. General Project Information II. Delamination Tests III. Mechanical Properties of LVL IV. Rheological Characteristics V. Outlook

12 LVL Lab-Scale Board Manufacturing Spread rate and procedure Lay-up procedure Pressing load Pressing time

13 LVL Lab-Scale Boards Mechanical Testing Results ASTM D 1037 Internal Bond Test Trus Joist Bending Shear Test

14 LVL Lab-Scale Boards Mechanical Testing Results ASTM D Single Cycle Edgewise Bending ASTM D Cycle Edgewise Bending

15 Outline I. General Project Information II. Delamination Tests III. Mechanical Properties of LVL IV. Rheological Characteristics V. Outlook

16 Rheology Summery of Previous Results Isothermal/Iso-Humid Cure Analysis RH unit has been installed to provide controlled conditions of humidity during rheological tests with the rheometer Isothermal/iso-humid cure analysis protocol of bonded wood specimen has been developed and successfully applied Bonded wood samples have been tested in dynamic oscillation using torsion mode Rheological creep experiments of the neat adhesive system in the parallel plate set-up

17 Rheology Sample Preparation and Characteristics 1. Lay-up Adhesive spread rate 170 g/m 2 (1.02 g) Wood thickness 0.58 mm Weight ratio adhesive / wood Pressing (4 min) 2. Pressing (4 min) F = 0.001, 0.01, 0.05 N/mm 2 ; T = 22 C 3. Disassembling 4. Punching out Circular Discs Diameter: 8 mm circular discs Conditioning at 20 C/65% RH and subsequent driyng over P 2 O 5 and under Nitrogen atmosphere

18 Rheology Sample Preparation and Characteristics 5. Stacking 2 Discs resinated on both sides Wood Species YP / SYP Mass 50 mg Thickness 1300 microns Density g/cm 3 6. Rheology - Measurement 8 mm parallel plate set-up a) Dynamic Oscillation Cooling Scan b) Frequency Sweep (Cooling)

19 Rheology Dynamic Thermal Scan; Storage Modulus 10 9 Storage Modulus [Pa] Neat Adhesive YP Composite YP Wood Neat Adhesive SYP Composite SYP Wood Temperature [ C]

20 Rheology Dynamic Thermal Scan; Tan(δ) Neat Adhesive YP Composite YP Wood Neat Adhesive SYP Composite SYP Wood Tan(δ) Temperature [ C]

21 Rheology MC of Frequency Sweep Experiments Storage Modulus [Pa] Tan(δ) Neat Adhesive SYP Composite YP Composite Frequency [Hz]

22 Microscopy Bond Line Thickness as a Result of Pressing Load Yellow Poplar N/mm N/mm N/mm 2 Southern Yellow Pine

23 Rheology Shift Factor Plots Neat Adhesive N/mm N/mm N/mm N/mm N/mm 2 5 Log a T YP SYP Temperature [ C]

24 Rheology Test Matrix Test Mode Torsion Material Dynamic Oscillation Neat Adhesive Bonded Wood Samples Southern Yellow Pine Yellow Poplar Creep?? Parallel Plate Dynamic Oscillation Creep

25 Outlook Next batch of lab-scale LVL with new adhesive technology (latex-isocyanate-blend) will be manufactured Reduction of spread rate of the 100% organic isocyanate-reactive in LVL lab manufacturing will be addressed Rheological measurements of weathered (steam cycled) bonded wood samples will be conducted in order to quantify the delamination process

26 Ackn owledge ment bill boehner charles paul joseph gabriel chip frazier

27 Remarks! Questions?