Wood Adhesives based on Polysaccharides

Transcription

1 Wood Adhesives based on Polysaccharides Emelie Norström, Linda Fogelström, Petra Nordqvist, Farideh Khabbaz and Eva Malmström KTH Royal Institute of Technology, Fibre and Polymer Technology, Stockholm, Sweden AkzoNobel, Casco Adhesives AB, Stockholm, Sweden International Conference on Wood Adhesives

2 Outline Introduction Wood Adhesives Gums Aim of study Experimental Preparation of dispersions Characterization Results and Discussion Conclusions Acknowledgements

3 Introduction Introduction Wood Adhesives Petroleum-based chemicals + Superior properties - Limited resource - Non-renewable - Impact on environment (formaldehyde) Important properties Bonding performance Water resistance Heat resistance

4 Introduction Gums Polysaccharides Relatively high molecular weight Locust bean gum / guar gum Obtained from seeds and bacteria Xanthan gum Tamarind gum

5 Aim of study Aim of study Investigate if it is possible to use gums as binders in wood adhesives Compare the properties with a commercial PVAc-based D2 wood adhesive

6 Experimental Experimental - Dispersion preparation Dry content: 6 wt% Stirring temperature: 60 C Stirring time: 6 h Biocide and fungicide: 0.15 wt%

7 Experimental Prepared dispersions Water dispersion Locust bean gum Guar gum Xanthan gum Tamarind gum Innovassynth Premcem 6 and 11 wt% Brown liquor dispersion Locust bean gum Reference: Commercial PVAc-based D2 wood adhesive

8 Experimental Characterization Viscosity ph Film formation Contact angle measurements Bonding performance

9 Experimental Bonding performance - Screening Bonding particleboards and veneers Adhesive: 360 g/m 2 Hot press 120 C 5 or 2.5 min 0.9 MPa Pull off test

10 Bonding performance - Veneers Experimental Bonding veneers using ABES Adhesive: 360 g/m 2 Hot press 120 C 2.5 min 0.7 MPa Heat and pressure Conditioning Pull Veneer Adhesive Pull Tensile shear strength Pressing test heads Heat and pressure

11 Experimental Bonding performance Wood panels Bonding wood panels according to EN204 and EN14257 Adhesive: 360 g/m 2 Hot press: 120 C, 10 min, 0.7 MPa Cold press: RT, 2h, 0.7 MPa Sawn into test pieces Conditioning Tensile shear strength test Pull Pull

12 Conditioning Experimental Method Tensile shear strength [MPa] wood panels Durability classes wood panels 7 days in standard atmosphere 10 D1 Water resistance Heat resistance 7 days in standard atmosphere, 3 h in water at 20±5 C, 7 days in standard atmosphere 7 days in standard atmosphere, 4 days in water at 20±5 C 7 days in standard atmosphere, 1 h in oven at 80 C 8 D2 2 D3 7 WATT

13 Results and Discussion Results and discussion Dispersion Molar mass [kg/mol] Dry content [wt%] Viscosity [Pa s] Ref: PVAc No information ~50 7.3± Locust bean gum ± Guar gum ± ph Xanthan gum ± Tamarind gum Innovassynth Tamarind gum Premcem Tamarind gum Premcem, 11 wt% Locust bean gum / brown liquor ± ± ± / ±

14 Contact angle measurements Results and discussion Film Contact angle [ ] after 1 s Ref: PVAc 64±4 31±2 Locust bean gum 76±0.5 71±2 Guar gum 80±3 77±3 Xanthan gum 75±4 68±4 Tamarind gum - Innovassynth Tamarind gum - Premcem Tamarind gum - Premcem, 11 wt% Locust bean gum - brown liquor 73±0.8 69±1 74±2 68±3 79±3 70±4 27±6 25±6 Contact angle [ ] after 40 s

15 Ref: PVAc Locust bean gum Locust bean gum - 4 layers Guar gum Xanthan gum Tamarind gum Innovassynth Tamarind gum Premcem Tamarind gum Premcem 11 wt% Locust bean gum - brown liquor Tensile shear strength [MPa] Bonding performance Veneers Results and discussion Dried Redried Dry content [wt%] ~

16 Ref: PVAc Locust bean gum Guar gum Xanthan gum Tamarind gum Innovassynth Tamarind gum Premcem Tamarind gum Premcem 11 wt% Locust bean gum - brown liquor Tensile shear strength [MPa] Bonding performance Wood Panels hot pressed Results and discussion D1 D2 D3 WATT D1 D2 WATT D3 0-2 Pressing: 120 C, 10 min

17 Tensile shear strength [MPa] Bonding performance Wood Panels cold pressed Results and discussion 16 D1 D2 WATT D1 D2 WATT Pressing: RT, 2 h 0 Ref: PVAc Locust bean gum

18 Conclusions Gums can be used as binders in wood adhesives Locust bean gum fulfill the criteria for a D2 and WATT 91 wood adhesive at 120 C Surprisingly, locust bean gum also fulfill the D2 and WATT 91 criteria when pressed at room temperature

19 Acknowledgements Wobama WoodWisdom-Net ERA-NET / Formas Casco Adhesives AB SP Technical Research Institute

20 Acknowledgements Division of Coating Technology

21 Thank you for your attention! Conclusions Gums can be used as binders in wood adhesives Locust bean gum fulfill the criteria for a D2 and WATT 91 wood adhesive at 120 C Surprisingly, locust bean gum also fulfill the D2 and WATT91 criteria when pressed at room temperature