Low VOC High Performance 1K Waterborne Polyurethanes For Wood Coatings Kevin Quinn Pacific Northwest Society for Coating Technology October 9, 2014

Definitions: PUD = Polyurethane dispersion (waterborne) 1K = 1 component coating PUD 1K PUD LZ-1 = 1K low VOC (<140g/L) self-crosslinking (at R.T.) PUD 2K = 2 component coating (polymer + crosslinker) 2K NCO = 2K commercial PUD coating with polyisocyanate crosslinker 2K Aziridine = 2K commercial PUD coating with polyaziridine crosslinker

Outline Introduction and background of topic Factors affecting PUD performance and VOC’s Process Polyurethane structural characteristics Morphology Raw materials/composition Crosslinking Comparison of 1K and 2K PUD attributes and performance Summary

Introduction and Background - Thermoplastic Waterborne Finishes for Wood Flooring Inadequate mar and black heel mark resistance Poor alcohol/ polar solvent resistance - 2K Waterborne Finishes for Wood Flooring Commercial approach typically using polyaziridines or polyisocyanates as crosslinking components with polyurethane dispersions Excellent chemical, mar and black heel mark resistance - Many Performance grade Floor Finishes for Wood Flooring are typically high VOC Solventborne Polyurethanes Waterborne Polyurethane at >270 g/L and may contain NMP as cosolvent. Target = Low VOC High Performance 1K PUD Resins that offer properties required for wood flooring applications & improved user friendliness

Introduction and Background Generation I = Soft 1K PUD containing NMP Generation II = Soft 1K PUD without NMP Generation III = Harder 1K PUD containing NMP Generation IV = Harder 1K PUD without NMP and capable of formulations at <140 g/L VOC coatings.

Factors Affecting PUD Coating VOC’s & Performance Synthetic process Polyurethane structural characteristics Particle morphology Raw materials/composition Crosslinking

PUD Prepolymer Process Water Dispersing Group OH HO NCO OCN + x Poly-isocyanate Polyol z NH2 H2N COOH 1) Neutralize 2) Water Waterborne Polyurethane Dispersion + Diluent Process Aid (viscosity control) Urethane Formation Urea Formation

Polyurethane Block Copolymer Structure and Phase Separation { Diisocyanate Chain extender or Diol Soft segment (SS) Hard segment (HS) urethane block

Raw Material Options for Balanced Performance Polyisocyanate: aromatic, aliphatic, functionality Polyol: polyesters, polyethers, polycarbonates Diols (hard segment modifiers): butane diol, cyclohexyl dimethylol, etc. Crosslinking Functionality: acetoacetonate, carbonyl, unsaturation (other options with applied energy)

Diisocyanates (Hard Segment) Type Advantages Aromatic TDI - Toluene Diisocyanate Hardness & MDI - Diphenylmethane Diisocyanate Low Cost Aliphatics HDI - Hexamethylene Diisocyanate Flexibility & TMXDI - Tetramethyl Xylene Diisocyanate Light Stability IPDI - Isophorone Diisocyanate H12MDI - Hydrogenated Diphenylmethane Diisocyanate

Polyols (Soft Segment) Type Advantages Disadvantages Polyethers Softness Adhesion to plastics (excluding PEO) Flexibility Weatherability (oxidizable) Hydrolytic Stability Poor solvent resistance- Solvent Resistance- (PPG’s) (PTMEG) Low Cost (PPG’s) Polyesters Adhesion Hydrolytic Stability Toughness Abrasion Resistance Exterior Durability Synthetic Flexibility Polycarbonates Hydrolytic Stability Cost Weatherability Availability

1K and 2K Ambient Crosslinked Coatings -Helpful for obtaining required performance while maintaining low VOCs 2K Crosslinked Polymer: Applicator mixes (1) crosslinker + (2) polymer base on the job: requires proper measurement and mixing, potential exposure Chemical reaction typically starts when crosslinker is added Mixture needs to be used before pot life expires 1K Self-Crosslinking Polymer: Crosslinking mechanism is built into the polymer Chemical crosslink reaction is activated as finish dries For on-site floor finishes this is at low or ambient temperatures (4˚-32˚C)

Chemical Resistance Test 1K PUD LZ-1 (140g/L) (50g/L) 2K Aziridine 2K NCO (275 g/L) Water (16 hr) 5 1.4% Ammonia (1 hr) 4 3 1% Spic and Span (4h) Red Wine (6 hr) Mustard (6 hr) MEK (1 hr) 50% Ethanol (1 hr) IPA (1 hr) MEK Double Rubs (100) Ethanol Double Rubs (100) Overall Total 47 43 48 44

Solvent Swells (Degree of Crosslinking) Cure Time at RT- Solvent 1K PUD LZ-1 without crosslink (140 g/L) (% Increase) with crosslink 2K Aziridine PUD (275g/L) 2K NCO PUD (% Increase ) 1 Day RT Cure   MEK 108 28 18 24 (slight white) IPA 36 16 11 14 (slight white) NMP dissolved 52 46 62 7 Day RT Cure 100 17 12 (slight white) 50 42

DMA Comparison of 1K and 2K PUDs

Black Heel Mark (Scuff) Resistance

Black Heel Mark Appearance on Wood non-crosslinked PUD (275g/L) 2K NCO Crosslinked 1K LZ-1 PUD (140g/L) 2K Aziridine Crosslinked

Wear/Abrasion Resistance 10 20 30 40 50 60 70 80 900 100 High VOC 1K PUD (with NMP) <140g/L 1K PUD 2K PUD ( Aziridine) Milligrams Wt. Loss/1000 Cycles Low Value Average High Value (NCO) Taber Abrasion

Adhesion: Solventborne Wood Stain Solventborne Stained Wood Panel 1K PUD LZ-1 Top Coat Competitive PUD Top Coat

Summary: Low VOC High Performance 1K Waterborne Polyurethanes Engineered for low VOC NMP-free formulation as a 1K wood floor finish comparable to two component PUD performance. No additional crosslinker required – no pot-life issues, no mixing issues, no handling issues, reduced waste and disposal cost Target: NMP free, <140g/L, 2K performance Easy to apply, user friendly, quick dry – multiple coats per day Polymer crosslinks upon application as it dries – as a result coating produced have: Rapid hardness development and abrasion resistance Cleaners- and alcohol- resistance on-par with 2K WB systems Comparable sport floor wear to commercial 2K crosslinked PUDs Excellent Adhesion to solventborne stains

Thank You For Attending and To The People Who Helped Make it Happen: Anthony Pajerski George Ahrens Jonathan Bird Svetlana Lerner Diawn Jones Tony Kropinak Matt Haney Lisa Blevins Charles Nelson Naser Pourahmady Bob Samelson Vic Stanislawczyk

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