Overcoming the Obstacles in Formulating Solvent-based Low VOC Acrylic Twocomponent Urethanes Jeffrey Janos Technical Specialist JPCL Webinar October 30, 2014 Overcoming the Obstacles in Formulating Solvent-based Low VOC Acrylic Twocomponent Urethanes Low VOC - Definition Regulations/Drivers Acrylic Resin Manufacture Characteristics of Low Mw Acrylic Polyols Formulation Methods to Enhance Properties Test Methods Summary What is a “VOC” in the coatings industry? Volatile organic compounds (VOCs) are organic compounds (typically solvents) that have a high vapor pressure at ordinary temperatures. Their high vapor pressure results from a low boiling point, which causes large numbers of molecules to evaporate into the surrounding air. These “volatiles” can form the precursors of chemical smog. In the United States and other locations globally, laws have been created to limit the amounts of these materials released into the atmosphere in an attempt to decrease air pollution. Present VOC Regulations National AIM Rule1 Category OTC 3,4/Canada California CARB South Coast *See Below Current Current New SCM 2010 Current Current Sanding Sealers 550 350 275 275** 275 Primer, Sealer, Under coaters 400 200 100 100 200 Quick Dry Sealers 450 200 275 100 200 Lacquer Sanding Sealer 680 550 275 275** 550 550 250 250 2502 2505 Varnishes (W/B, S/B, 2K ) 450 350 275 275** 350 Conversion Varnish 725 350 275 275** 725 - - - - 450 680 550 275 275** 550 - 680 275 275** 680 730 730 730 730*** 730 SEALERS STAINS Stain, Semi-transparent TOPCOATS/FINISHES Conjugated Oil Varnish Lacquers Clear Brushing Lacquer Shellacs – Clear See “footnotes” at end of presentation Manufacture of Acrylic Polyol Resins Processes Solution Batch & Semibatch Process Continuous Stirred-tank Process Plug Flow Process Polymer “Batch” Reactor S o lv e n t, M o n o m e r, In itia to r A n e v a p o ra to r A b ig ta n k Or A v a lv e U s e D ire c tly Methods of Formulating Low VOC Acrylic Urethanes Use of low viscosity acrylic polyols Reactive diluents Use of low viscosity isocyanates Exempt solvents Fillers Low Viscosity Acrylic Polyols Acrylic Resins with Low Viscosities Explanation Low molecular weight → Lower hydrodynamic volume Molecules with fewer polar groups (-COOH, Urethanes, etc.) → Less intermolecular hydrogen bonding Low polydispersity (Mw/Mn) → Less high Mw compounds Using branched molecules → Lower hydrodynamic volume Using solutions with good solubility → Formulation of gel-like structures prevented Low glass transition (Tg) temperatures → Lower hydrodynamic volume Low Mw Acrylic Polyols Positives Negatives Lower solvent release Slower cure Ability to apply with less coats Weatherability Chemical resistance Corrosion resistance Lower abrasion resistance Slower hardness development More difficult to control gloss Cost Formulation Tips to Enhance the Performance of Low Mw Acrylic Polyols Slower Cure Increase catalyst levels Use more reactive diluents Use modified “fast cure” polyols Use more reactive isocyanates Use blends of other faster reacting resins with the acrylic Formulation Tips to Enhance the Performance of Low Mw Acrylic Polyols Weatherability Use combinations of hindered amines & UV absorbers 7.0 Minimize use of monomers with poor UV resistance 5.0 Use blends of higher Tg & lower Tg acrylics Increase opacity Nano-TiO2 Minimize the amount of catalyst in the formulation Color Change QUVA 8.0 473 Hrs 1000 Hrs 6.0 1639 Hrs ΔE 4.0 3.0 2.0 1.0 0.0 Acrylic A Acrylic A w/ UVA Acrylic B Acrylic B Polyester Polyester w/UVA w/ UVA Formulation Tips to Enhance the Performance of Low Mw Acrylic Polyols Chemical/Corrosion Resistance Increase crosslink density Increase Tg of film Use blends of higher Tg & lower Tg acrylics Hydrophobic additives Over indexing with isocyanates Formulation Tips to Enhance the Performance of Low Mw Acrylic Polyols Lower Abrasion Resistance Incorporation of resin “tougheners” like linear acrylics, polyesters, amines & caprolactones Surface active ingredients Slight under indexing with isocyanates Formulation Tips to Enhance the Performance of Low Mw Acrylic Polyols Slower Hardness Development Increase catalyst amounts or change to a more reactive one Use blends of higher Tg & lower Tg acrylics Increase pigment to binder ratio König Hardness over Time 140 120 H a r d n e s s 100 80 1 Day 3 Days 60 7 Days 40 30 Days 20 0 High Mw Med. High Mw Med. Mw Acrylic Urethanes Low Mw Formulation Tips to Enhance the Performance of Low Mw Acrylic Polyols Difficult to Control Gloss Amorphous, treated silica aerogels High molecular weight waxes Polymeric resin matting agents Formulation Tips to Enhance the Performance of Low Mw Acrylic Polyols Cost Increased isocyanate demand Higher solids Use of specialty monomers Formulation Tips to Enhance the Performance when using Exempt Solvents USA → Acetone, methyl acetate, PCBTF, t-BAC, dimethyl carbonate & propylene carbonate in some locations Canada → Acetone, methyl acetate, PCBTF, t-BAC Global → Check local regulations Formulation Tips to Enhance the Performance when using Reactive Diluents Low Tg acrylics → Can improve flexibility, weathering Low Mw polyesters or diols → Flexibility OH functional oils → Castor types, add color to system Oxazolidine → Moisture activated Other amine functional resins → Ketimine, aspartic, aldimine Formulation Tips to Enhance the Performance when using Fillers Minerals → Low oil absorption talcs, barytes, carbonates Glass or mineral spheres → Low density, minimal surface area but expensive Polymeric → Special purpose but expensive Formulation Tips to Enhance the Performance when using Low Viscosity Isocyanates Low viscosity HDI trimers (Isocyanates) Best performance HDI allophanates Lower crosslink density HDI uretdiones Lower crosslink density Test Methods Hardness & Hardness Development Pencil – ASTM D3363 Pendulum Hardness – ASTM D4366, ISO1522 6B 5B 4B 3B 2B B HB F H 2H 3H 4H 5H 6H 7H 8H 9H Softer Harder König Pendulum Hardness - Clears 140 120 Swings 100 80 60 40 Days 20 0 Acrylic Urethanes 1 3 7 30 Test Methods Weathering QUVA & B – ASTM G154 Weather-O-Meter – ASTM C1442 Exterior Exposure (Florida, Arizona, etc.) – ASTM 7869, 7356 Test Methods Corrosion Resistance Salt Spray – ASTM B117 Cyclic Prohesion – ASTM G85 Test Methods Dry Time Mechanical Method – ASTM D5895 Manual “Finger” Method – ASTM D1640 Pot-life Double Initial Viscosity – ASTM D1084 Test Methods Abrasion Resistance Tabor Method – ASTM D4060 “Falling Sand” Method – ASTM D968 Test Methods Gloss Specular Gloss – ASTM D523 Film Appearance Distinctness-of-Image – ASTM D5767 Summary VOC regulations are becoming more & more significant to coating manufacturing companies. Five primary methods of developing low VOC acrylic urethanes include use of low molecular weight polyols, reactive diluents, low viscosity isocyanates, exempt solvents & fillers. Low molecular weight acrylic systems have the lowest solvent content & are globally accepted. Exempt systems are only applicable is regional areas. Many short-comings of using low molecular weight acrylics can be overcome or minimized by careful formulating techniques. While the descriptions, designs, data and information contained herein are presented in good faith and believed to be accurate, they are provided for guidance only. Because many factors may affect processing or application/use, BASF recommends that the reader make tests to determine the suitability of a product for a particular purpose prior to use. NO WARRANTIES OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, ARE MADE REGARDING PRODUCTS DESCRIBED OR DESIGNS, DATA OR INFORMATION SET FORTH, OR THAT THE PRODUCTS, DESCRIPTIONS, DESIGNS, DATA OR INFORMATION MAY BE USED WITHOUT INFRINGING THE INTELLECTUAL PROPERTY RIGHTS OF OTHERS. In no case shall the descriptions, information, data or designs provided be considered a part of BASF's terms and conditions of sale. Further, the descriptions, designs, data, and information furnished by BASF hereunder are given gratis and BASF assumes no obligation or liability for the descriptions, designs, data or information given or results obtained all such being given and accepted at the reader's risk. ® registered trademarks of BASF Group. © BASF Corporation, 2014 Footnotes * OTC States: Connecticut, Delaware, District of Columbia, Maine (except varnish & stain), Maryland, Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, Virginia (Only Northern Virginia & Fredericksburg Emissions Control Areas which includes: Arlington, Fairfax, Loudoun, Prince William, Stafford & Spotsylvania Counties; Cities of Alexandria, Fairfax, Falls Church, Manassas, Manassas Park & Fredericksburg). ** Quart exemption has been eliminated for Varnishes, Sanding Sealer and Lacquers in the South Coast Air District *** Shellacs manufactured after 12/31/06 are not allowed to be used on wood flooring in South Coast 1- EPA revising the National AIM Rule similar to OTC Phase I limits 2- Interior 3- RI adopted OTC Phase I 4- LADCO States – OH, IL & IN has adopted OTC Phase I limits, plus added Conjugated Oil Varnish 5- Interior Wiping Stains (Canada only) Questions?