Bio-based Solutions for High-Performance Polyurethane Adhesives Angela Smits Bio-based Adhesives Conference 213
Bio-based building blocks sustainable solutions CRODA: Naturally derived speciality chemicals and sustainable products Global trend towards bio-based raw materials Automotive: renewability targets, light weight design Electronics: green mobile phones, computers, gadgets Sportswear: positive health and environment image Packaging: improve carbon footprint Bio-based monomers: special dimer fatty acid, dimer diol, dimer diamine Bio-based polyester polyols up to 1% bio-based Durability: impact modifiers for structural epoxies
Different forms of dimer fatty acids technology derived from natural oils Dimer acid PRIPOL COOH COOH Dimer diol PRIPOL OH OH Dimer diamine PRIAMINE H 2 N NH 2 Polyesters polyols made with dimer acid (or dimer diol) PRIPLAST HO---- E--E ----- OH n
Dimerised fatty acids technology Properties Large hydrocarbon part (C 36 ) hydrophobic, water-repellent hydrolytic resistance of derivatives thermal resistance affinity for low polarity matrices and surfaces low T g O=C HO Irregular non-crystalline structure flexibility good flow and wetting low modulus, no strain hardening no shrinkage C=O OH Di-functional constituent for polyamides polyesters polyimides polyurethanes, etc.
The PU adhesives in this study Polyurethanes from 1 single polyol; or conventional polyol Reactive PU adhesives: prepared with excess solid MDI, moisture cured PUD adhesives: prepared with IPDI, OH functional PU, tested without cross-linking Incorporating dimethyl propionic acid DMPA for water dispersion Polyester polyol PUD particle size (nm) Hexane diol adipate 18 3192, semi-crystalline 45 3293, semi-crystalline 1% bio-based 82 3238, amorphous 1% bio-based 125
Flexibility of reactive polyurethanes flexible and no strain hardening Modulus (kg/cm 2 ) 2 Mw of the polyols is 2 NCO:OH = 2 Mechanical properties were measured after full cure 16 12 8 3192 semicrystalline 1838 amorphous HDO-adipate 4 2 4 6 8 Strain (%)
Low T g of polyurethanes flexibility also at low temperatures Glass transition temp. [ o C] 1-1 -2 Recipe : 1 Polyol 2 Butanediol 3.1 MDI P1838 (*) = 1-1-2.1-3 HDO-adipate PTMEG 3192 3196 1838 PPG 1838 (*) Polycaprolacton 319
Adhesion to a variety of substrates PUD lap shear adhesion: good from smooth to fibrous substrates 2 rigid PVC 6 birch wood 1.5 Adhesion (MPa) 1.5 Adhesion (MPa) 4 2 HDO-adipate 3192 3293 3238 3238 3293 PUD was applied to both sides of the film, dried and re-activated at 7 o C. A steel weight was used to join the two parts. Test on an Instron tensile tester.
Adhesion to a variety of substrates Reactive PU lap shear: High strength to hard, smooth plastics Mw of the polyols is 2 NCO:OH = 2 NB = no break, slipped from the clamps SF = substrate failure Adhesion (MPa) 3 2.5 2 1.5 1.5 NB polyamide-6 Adhesion (MPa) 3 2.5 2 1.5 1.5 NB polycarbonate Adhesion (MPa) 1.8.6.4.2 1838 SF 3192 SF HDO- Adipate PET film PTMEG Adhesion (MPa) 2 1.5 1.5 1838 SF 3192 SF HDO- Adipate polystyrene PTMEG 1838 3192 HDO- Adipate PTMEG 1838 3192 HDO- Adipate PTMEG
Adhesion to hard, smooth substrates Reactive PU on polycarbonate 1% bio-based Adhesion (MPa) 2.5 2 1.5 1 adhesives based on conventional polyols NB NB NB Mw of the polyols is 2 NCO:OH = 2 NB = no break, slipped from the clamps.5 HDO- PPG PTMEG Adipate 1838 3192 3238 3293 3286
Adhesion to low-energy substrates untreated PE Mw of the polyols is 2 NCO:OH = 2.6 Adhesion (MPa).4.2 adhesives based on conventional polyols PEG PTMEG HDO- Adipate 3192 1838 3293 3286
Low moisture absorption of PU brings water resistance versus other polyols Moisture uptake at 23 o C (%) 2 1.6 Recipe : 1 Polyol 2 Butane diol 3.1 MDI 1.2.8 Conditions : 1 week in H 2 O dist..4 3196 1838 Poly BD 319 HDO carbonate 3192 HDO-adipate Polycaprolactone BDO-adipate PTMEG PPG
Water resistance of PUD PUD without cross-linker as good as cross-linked HDO-adipate (rating 3-4) Adding 5% NCO cross-linker makes -based films nearly water resistant Spot test: water 16h Rating = very good, no mark; 5 = poor, damaged Polyester polyol Water resistance Hexane diol adipate 5 3192 3 3293 2 3238 3
Durability: Thermo-oxidative stability of reactive PU based on Cured polyurethane hot melt films Aged 4 weeks at 14 o C Retention of mechanical properties Retention of properties 1% 8% 6% 4% 2% Tensile strength Elongation unsaturated diol; no ether / ester % HDO-Adipate 3192 PPG PolyBD
Durability: Hydrolysis resistance PU aged in hot water 1% bio-based Retention of tensile strength [%] 1 8 6 Recipe : 1 Polyol 2 Butanediol 3.1 MDI Conditions : 1 week in H 2 O (dist.) at 9 o C 4 2 3286 3238 3293 PTMEG HDO-adipate
Summary of bio-based technology dimer-based polyols: Unique combination of hydrolytic and thermo-oxidative stability Good mechanical properties: flexible, no strain hardening, low T g Exceptional adhesion to a multitude of substrates Excellent water resistance High renewable content, up to 1% To protect substrates from moisture To improve adhesion to low polarity substrates (plastics) To adhere dissimilar materials To obtain flexible adhesives
Thank you!
PU-dispersion basic recipe used, OH-terminated 1 g 3192, 13 g DMPA at 13 C / 25 mbar for 4 minutes Break vacuum with N 2, cool to 11 C, add 31g IPDI in 1 minutes, add acetone 35 g Cool to 6 C and add 35 g acetone, stir until a clear solution is obtained Cool to 5 C, react to NCO-number < 1 (theoretical OH-value 3.6) Add 11 g TEA, stir for half an hour Add 22 g water while intensively stirring, until phase inversion (CRITICAL step) Then remove acetone at 5 C under gradually increased vacuum (to prevent foaming), down to 1 mbar DMPA = dimethylol propionic acid; two OH-groups to build into the polyurethane, remaining carboxylic acid group to disperse into water