ASC Fall Conference October 18, 2016

Transcription

1 ASC Fall Conference October 18, 2016 NonMigratory Surfactants in Emulsion Polymerization By : Dr. Steven Y. Chan

2 Agenda Introduction Surfactants in Emulsion Polymerization NonMigratory Surfactants (NMS) Reactivity of NMS Dry Film Properties (Clear) Performance Testing in PSA Conclusion

3 Introduction Global Adhesives and Sealant Market by million metric tons/ $60 billion Waterborne Systems Replacing Solventborne as Result of VOC Directives and Legislation Majority of Waterborne Systems Utilize Emulsion Polymers WB Pressure Sensitive Adhesives at $8.5 billion by 2020 Tends to have Worse Water Resistance Presence of water sensitive materials like surfactants

4 Surfactants In Emulsion Polymerization Adsorption on Surface and Interfaces Particle Size Nucleation and Colloidal Stability Energy Barrier to Prevent Particle Flocculation or Coagulation D.C. Blackley Emulsion Polymerization, Theory and Practice, London: Applied Science Publishers., 1975

5 Conventional Surfactants Physical Adsorption via Hydrophobic Interaction (Weak) Emulsion Stability Failure Desorption of surfactant due to external stresses Shear, temperature, formulation ingredients Water Sensitivity Release of surfactant during drying/film formation Surfactant accumulation Surface effects gloss, adhesion, blocking & water resistance Bulk effects water uptake, protection, pigment binding, swelling

6 Non Migratory Surfactants (NMS) CoPolymerizable Surfactants Irreversibly Grafted through Covalent Linkage Strong Chemical Bond Gives Superior Colloidal Stability No Surfactant Release During Drying Homogeneous Distribution of Surfactant Improves Dry Film Properties

7 NonIonic NMS NonIonic Polymerizable Surfactant (NNMS) Alkenyl/Carboxyl Functional Ethoxylate Molecular Weight of 1100 (NNMS1) and 1600 (NNMS2) (EO)nX Steric Stabilizers COOH Steric Stabilization

8 Anionic NMS Anionic Polymerizable Surfactants (ANMS) Modified Alcohol Ethoxylate Phosphate Ester Electrostatic and Steric Stabilizer Efficient during particle nucleation and growth stage (EO) n OPO 3 H Electrostatic Repulsion

9 Experimental Seeded SemiContinuous Emulsion Polymerization Insitu or separate seed Neat monomer feed or preemulsion feed Process Optimization ph control to avoid aqueous phase polymerization Semicontinuous feed to avoid excessive burial of surfactant Starved feed conditions to maximize grafting

10 Surfactant Reactivity BA/MMA/AA, Conventional Anionic in Seed Stage, N NMS1 in PreEmulsion Unreacted Surfactant Separated from Polymer with Ultrafiltration and Quantified via HPLC 70% of NNMS1 Reacted after postcooking with monomer starved conditions Xaccum End of feeding time Feed 4 hr Xsurf 4 hr Feed 2 hr Xsurf 2 hr Relative Time

11 Reactivity of ANMS BA/MMA/MAA, All ANMS Emulsion 45% Polymer Solids and 2.5 phm or 1.14wt% Surfactant on total Unreacted Surfactant Separated via Ultracentrifugation and Quantified via ICPMS Only wt % Recovered or 8.5% >90% ANMS Reacted

12 NMS Effect on Reaction Kinetics 500 M. Wt., g/mole x Mn Mw SAT = Saturated Alcohol Ether Phosphate Allyl/Propenyl = Competitive Reactive Surfactants 0 Degradative Chain Transfer Observed for Competitive Allylic and Propenylic NMS Surfactants Resulting in Lower Molecular Weight

13 Surfactant Exhudation AFM of Styrene Acrylic Film Dried and Washed with Water NPE30 NNMS1 Pinholes Observed None

14 Transmission Haze (%) Better Water Whitening Immersion time (hrs) ANMS R ANMS ISO Linear Linear: 1 days ANMS, KPS initiated, ANMS R, tbpb initiated vs linear and isobranched alcohol ether phosphates, all 2.5 phm ANMS : 7 days

15 Lower Water Transmission Rate BA/MMA/AA Latex Film High Water Diffusion Rates with Conventional Surfactant Suggest Poor Protective Properties Air Substrate Upper Lower Water Transmission Rates Lower Interface Upper Interface NPE SLS NNMS NNMS

16 Improved Water Repellency Water Runs Off much Faster from a Film Based on ANMS ANMS NaDPDS Contact Angle : ANMS = 71, Conventional = 43 for Sodium Alkyl Diphenyl Disulfonate (r)

17 Increased Hydrophobicity in Acrylic Emulsion Contact angle of water droplets on dried emulsion films prepared with different emulsifiers Conventional Competitive Maxemul 6106 Higher contact angle indicates more hydrophobic film, leading to better water resistance

18 Lower Foam 50 ml of Emulsion in a 4 oz Jar Hand Shaken 5 times ANMS NaDPDS

19 NMS in PSA Shear Strength Tensile Strength (kn) or inplane Cohesion Failure Test Conditions Films obtained from a 60/40 PSA/Ethanol mix Applied on polyester substrate Cured for 5 at 120 C and 24hrs at ambient Contact area: 20mm x 20mm, 5 kg loaded for 60 sec

20 Max load (N) Max load (N) Improved Shear Strength Effects of Film Thickness and Polymer Composition Wet film thickness from 50 to 200 µm, dry films obtained from a 60/40 PSA/Ethanol mix 3.21 phm BA/MMA/MAA/HEA BA/MMA/MAA Wet film thickness Allylic NPEs ANMS Wet film thickness ANMS 3.21 HEA free A3232 HEA free Higher shear strength for ANMS vs allylic NMS and conventional

21 Conclusion NonMigratory Surfactants are Effective in Emulsion Polymerization Chemically Grafted to Emulsion Particles Improved Performance in Dried Film Water whitening, water retention, WTR, high contact angle, lower foaming tendency Better Properties in PSA Water immersion, cohesion Improve the Performance of Waterborne Systems to the Next Level that Conventional Surfactants cannot.

22 Acknowledgement Jo Grade from Gouda, Netherland Nathan Noyes, New Castle, DE

23 Thank You!