New Developments in Aromatic Curative Technology

Transcription

1 New Developments in Aromatic Curative Technology Yong Tang, Ph.D.

2 Outline Hand Applied Roof Coating» MOCA replacement» Development of new curative package with use of Design of Experiment (DOE) Use of these new curative package (E500 series curatives)» Spray polyurea coatings» Cast elastomers Conclusions

3 Albemarle Corporation Global provider of specialty chemicals products. Headquartered in Baton Rouge, LA, USA. Diversified mix of solution-based products and custom services sold to a wide range of customers and end markets.» Over 3,000 customers in 100 countries; Over 3,500 employees around the world.» Operate 40+ facilities encompassing production, R&D, and administrative. offices in North and South America, Europe, the Middle East and Asia. Two global business units:» Catalyst Solutions» Performance Chemicals Strong History of Growth Fine Chemstry Services Stabilizers 11% & Curatives 9% Mineral FR 6% Bromine Derivatives 36% Catalysts 38%

4 Background MOCA is one of the most commonly used curatives in PU, due to cost and performance, however represents a significant hazard to workers. The sun-set day of MOCA is 22 Nov New regulations in the world (REACH, China, etc.) driving very high costs and long time frames for registration of new chemicals. Blending of registered products is a cost effective and rapid way to explore new applications, which can provide potential alternatives to MOCA. New curative applications:» Coatings (spray or hand applied) Protect concrete roofs and decking Waterproofing required» Cast Elastomers» Adhesives and Sealants

5 Japan Roofing Market The Japan roof coating market is about 50% asphalt technology, 30% PU coatings and 20% PVC sheeting. Market shares have roughly stayed the same for the last 10 years. Total market size is flat. 30% 20% 50% Asphalt Technology PVC sheeting PU coating MOCA is the dominate curative for the PU coating due to cost and performance. The largest application for MOCA in Japan is for PU Roof Coatings, about 1500 tons/y.

6 Roofing Materials and Hand Applied System in Japan Material classifications» Urethane system» Acrylic system» Chloroprene system» Asphalt system Hand applied system two-component» A side: TDI based prepolymer» B side: curative (i.e. MOCA) Japan Roof Coating

7 Roof Coating Physical Property Targets Property Target Pot-life (min) Hardness (Shore A) Tensile Strength (psi) >355 Tear Strength (lb/in) >84 % elongation >450% customer specifications Japanese Industrial Standard: JIS A 6201

8 Current Curative System in Japan PU Roofing MOCA in 2K polyurethane coating» Methylene bis(ortho-chloroaniline) Cl Cl H 2 N NH 2» Used to cured TDI-based isocyanate prepolymer» Long pot-life (~60-90 minutes)» Gives desired physical properties

9 MOCA Toxicity In 2010, IARC reclassified MOCA from a Class 2a carcinogen (probably causes cancer) to a Class 1 carcinogen (known to cause cancer). (IARC, vol. 57, vol. 99, in prep.). Potential worker exposure to MOCA in Japanese roof coating. Need to develop alternative curative technology to MOCA delivering desired performance.» Easy application» Long pot life» Desired physical properties

10 Experimental Materials Material Source 3.6% NCO TDI Prepolymer Air Products Airthane PPT-80A DETDA (E100) Albemarle DMTDA (E300) Albemarle Calcium carbonate Aldrich Dioctyl phthalate Aldrich Equipment A-side TDI-based 3.6% NCO liquid at RT B-side Amine Plasticizer (DOP) Filler Dual-axis high speed mixer Draw-down mold Brookfield DV-I Viscometer

11 Test Methods Coating Physical Properties:» Room temperature cure Demold after 1d Testing after 7days in condition room» Shore A hardness (ASTM 2240)» Tensile strength and elongation (ASTM D-412)» Pot-life: Brookfield viscometer (100, 000 cps)

12 Results Quick Screen Curative Pot life (min) Hardness (Shore A) Tensile (psi) Elongation (%) Target >362 >450 MOCA/PPG DMTDA (E300) DETDA (E100) SBMDA (E420) Did not cure Screening Blend Screening Blend DMTDA has extended pot-life, but lower physical properties DETDA is too fast, but delivers good physical properties SBMDA did not cure (>24 hrs) Initial Screening blends achieved desired pot-life, but mechanical properties didn t meet the targets

13 Viscosity (cp) Pot Life Measurement Viscosity Rise of Coatings Time until viscosity reaches 100,000cP Time (minutes) E100 Screening blend 1 Screening Blend 2 E300

14 Use of Plasticizers Common in PU Coating Formulations Pot life and elongation increased, but tensile strength decreased Wt% DOP in coating 0% 7% 16% 28% Target Pot Life (min) Hardness (Shore A) >45 Tensile (psi) >362 Elongation (%) >450

15 Viscosity (cp) Effect of Plasticizer on Pot Life Viscosity Rise as Plasitcizer Added Curative Blend 1, PPT-80a, DOP Time(min) 0 wt% 7 wt% 16 wt% 28 wt%

16 Effect of Plasticizer 17wt.% DOP 6 wt.% DOP 0 wt.% DOP

17 Effect of Iso/Amine Ratio (Index) Tensile Strength and % Elongation Curative Blend 1, PPT-80 Index Scan ,90 0,95 1,00 1,05 1,10 1,20 1,30 Tensile (psi) Elongation (%)

18 Pot-life (minutes) Effect of Iso/Amine Ratio (Index) 55 Pot-life vs. Index 50 1, ,1 1, ,9 30 0,85 0,95 1,05 1,15 1,25 1,35 Index

19 Need to Develop New Approach A need exists - customers want to eliminate MOCA use in these PU roof coatings. But after 10+ years of formulation effort by Japanese customers and suppliers, no single amine curative system has been able to deliver the cure speed and physical properties of MOCA. Screening blends are able to achieve desired pot life, but mechanical properties still need to be improved. Need to develop new approach to find alternative curative technology to MOCA.

20 Use of Design of Experiment (DoE) Software Use multi-component blends of registered amine curatives DoE Software: Minitab 15» Factor levels determined in this quick screen Index: 1 to 1.3 Plasticizer: 7 to 16 wt.% in total coating formulation Curative B: 50 to 67% in curative blend» Factorial 2-level 3 factors 8 runs, 1 replicate

21 Plasticizer Curative B Curative B DoE Results Pot Life Contour Plots of Pot Life Index Index Plasticizer Index, plasticizer, and wt.% curative B all increase pot-life Target: 60-90

22 Plasticizer Wt.% Curative B Wt.% Curative B DoE Results Tensile Strength Contour Plots of Tensile Index Index Plasticizer Plasticizer * index plot shows slight curvature, indicating slight interaction Curative B * index and curative B * plasticizer do not interact to affect tensile Target >355

23 Plasticizer Wt.% Curative B Wt.% Curative B DoE Results - % Elongation Contour Plots of Elongation Index Index Plasticizer Lines are curved, indicating strong interactions between variables. The effect of plasticizer and curative B loading are stronger at a 1.0 index than at 1.3; at lower plasticizer loading, the curative B has a greater impact on elongation. Target >450

24 Plasticizer Wt.% Curative B Wt.% Curative B DoE Results - Hardness Contour Plots of Hardness Index Index Plasticizer The lines are generally straight, except sight curvature for curative B * plasticizer interaction Target >30-70

25 Optimized Blend Plasticizer Curative B Properties Desired Predicted Actual* Pot Life (min) Tensile (psi) > % elongation > Hardness (A) Summary DoE very effective and powerful technique for optimizing the formulation Actual results have good correlation with predicted results

26 Status DoE effectively used to create two new curative blends which met all of the desired properties of MOCA. These two blends (E520 and E534) have been commercialized and are being used hand applied coatings (i.e. roofing coatings). Now looking at curative blends for other PU applications.» Spray polyurea coating» Cast elastomer

27 Low Pressure Static Mixed Spray System Tests: Tensile Tear Hardness Adhesion

28 Mechanical Properties of Spray Coating Containing E420 and E500 Curatives Formulation Δ E420 E520 E534 Gel Time(S) Tensile (psi) Modulus (psi) Elongation % Tear resistance (lbf/in) Hardness (shore A) Adhesion Δ The equivalent ratio between E420/E100 and The adhesion test was conducted with hardy board without base coating.

29 Physical Properties of Spray Coating with Varying Equiv Ratio of E100/E520 Formulation Equiv.ratio E100:E520 80:20 70:30 60:40 40:60 30:70 20:80 Gel time (sec) Tensile (psi) Modulus (psi) Elongation % Tear resistance (lbf/in) Hardness (shore A) Gel time increases with increase of E520 in B side The mechanical properties have the maximum values at Equiv ratio of E100/E520=70/30; and minimal values at 20/80.

30 Mechanical Properties of Cast Elastomers Containing E500 Curatives Sample Tensile (psi) Elongation (%) Young s Modulus (psi) Hardness (shore A) Compression set % Resilience % Tear Resistance (lbf/in) TDI-wt.4% NCO/E TDI-wt.4% NCO/E TDI-6 wt.% NCO /E TDI-6 wt.% NCO /E MDI- 4wt.% NCO/E MDI-4wt.%NCO/E / 356 MDI-4wt.%NCO/E MDI-6wt.%NCO/E / Deliver considerable tensile strength, but the hardness still needs to be optimized. MDI/E500 gives better performance compared with TDI/E500 system

31 Comparison of UV Performance of E300 and E500 E300 E520 E300 E hrs UV exposure ΔE E300 =61.2 ΔE E500 =32.9 Before UV exposure After UV exposure E500 exhibits better weatherability compared with E300.

32 Conclusions Demonstrated it is possible to design blends of amine curatives to produce coatings with similar pot-lives and physical properties as coatings cured with MOCA. These blends are liquid and have an improved HSE profile versus MOCA and thus provide viable alternatives. Used DoE to predict a formulation that met and exceeded performance targets. E500 series curatives exhibit great potential in spray polyurea coating. The cast elastomer made of E500 series curatives deliver considerable tensile strength, but the hardness still needs to be optimized by special selection of prepolymer blends to match the application. E500 curatives have better weather ability compared with E300. Future work will be to apply this approach to developing new products in other polyurethane markets.

33 Thank You! Yong Tang, Ph.D. Sr. R & D Engineer yong.tang@albemarle.com Paul Wiggins, Ph.D. R & D Advisor paul.wiggins@albemarle.com w w w. a l b e m a r l e. c o m