Cure evaluation of Intelimer latent curing agents for thermoset resin applications

Transcription

1 Cure evaluation of Intelimer latent curing agents for thermoset resin applications Michael S. Lowry, Ellen M. O Connell, Jean L. Vincent, Richard J. Goddard, Thomas A. White, John Zheng, Ray Wong, Steven P. Bitler Air Products and Chemicals Inc. Landec Corporation Presented at a meeting of the Thermoset Resin Formulators Association at the Hilton Suites Chicago Magnificent Mile in Chicago, Illinois, September 15-16,

2 One-component Formulations Epoxy Adhesives and Composites Unsaturated Polyester CIPP 2

3 Formulations Standard Two-component Formulations: Materials suppliers Formulator End user A + B A B A B Resin Traditional Curing Agent Delivering the Difference: One-component Formulations: Materials suppliers Formulator End user A + C AC AC Resin Latent Curing Agent 3

4 Protecting active ingredients: Encapsulation Core Shell Encapsulation Matrix Encapsulation Wall Active Ingredient 4

5 What are Intelimer polymers? Crystalline polymers with sharp, well-defined melt temperatures Crystalline State Amorphous State Heat Cool Impermeable Permeable 5

6 Latent curing agents via Intelimer polymer encapsulation Curing agents can be encapsulated with Intelimer polymers to control their release into thermoset resin. Crystalline structure Encapsulated Curing agent Reactivity of the curing agent is blocked until the polymer melts. 6

7 7 Epoxy applications

8 Epoxy Chemistry Tertiary Amine Catalyzed Homopolymerization R O Epoxy Resin O + R R N R Tertiary Amine N R O O R O O R O N O R O O etc. O O R Goal: To extend pot-life of tertiary amine curing agents while maintaining fast cure speed in epoxy homopolymerization reactions. 8

9 Intelimer encapsulated amines demonstrate prolonged pot-life Product Name Structure Encapsulation Method Pot-life (25 o C) Imicure EMI-24 None. 9 hours Intelimer 7024 Polymer Matrix encapsulation. 1 week Intelimer 7004 Polymer Catalyst covalently attached to polymer. > 1 year 2 phr active in liquid epoxy resin (LER) Time required for formulated sample to double in mix viscosity. 9

10 Identifying gaps for new product development: Performance Benefits (Intelimer 7004) Long latency (months) Fast activation at T > T o High T g (110 C) Performance Needs (Product Development) Adjustable thermal stability Lower onset temperature Faster reaction at T < 100 C Time to Max Exotherm (min) Time (min) Existing Product: Intelimer 7004 DSC Cure Profile < 5 min at T o 10 T o Temperature (C) 10

11 Achieving chemical control over material performance: Adjust melt temperature (and pot-life) by modifying the Intelimer polymer chain length. Intelimer Polymer Melting Temperature 11

12 Achieving chemical control over material performance: Adjust reaction profile (and cure speed) by modifying the curing agent that is encapsulated by the Intelimer polymer. e.g., Epoxy Reaction Profile Scaled Heat Flow (a.u.) Different amines. Tunable onset temperatures! Intelimer MP / curing agent release point Encapsulated Curing Agent 12

13 Rapid cure at thermal onset Observation: < 5 min reaction at thermal onset. Replacing current catalysts with appropriate amines will enable snap cure across a broad range of temperatures. 13

14 Benefits of encapsulation approach using Intelimer polymer Chemistry: Crystalline structure protects catalyst Tunable switch temperature (thermal stability) Control cure properties by modifying catalyst Applications: Long latency improves ease in use Mix ratio Integration time Expedited work process Long latency simplifies transportation and shipping Fast reaction at thermal onset 14

15 Unsaturated polyester applications 15

16 Cured In Place Pipe (CIPP) A polymer liner used to re-line sewer pipes that leak Pre-fab: Felt tube impregnated with unsat polyester resin and catalyst Shipped on ice to site Over-the-Hole Felt tube wet-out with liquid resin/catalyst on the job site For bigger jobs, too heavy to ship on a truck Installed by inversion, push through existing pipe with water pressure Cured with hot water/steam at 180F for 4-8hrs Diameters of 4-96, thickness varies by application 16

17 CIPP Some loss of pipe id, but make up for it in improved flow Mostly (> 85%) unsaturated polyester resin 17

18 CIPP Chemistry Unsaturated polyester resin Exothermic reaction Cured with: Free radical initiation UPE resin + organic peroxide in combination with an accelerator (e.g., cobalt) Hot cure with water or steam ( F, 4 hrs) Depends on climate, pipe size, weight, etc Pipe is about 85% by weight resin 18

19 Encapsulated cobalt catalyst Encapsulated cobalt (2 wt% Co) Solid, mp 65 C Long pot-life, very important for CIPP Intelimer 6050 Polymer Gel time at 20 o C, hours Cobalt Nap Intelimer 6050 No Promoter 19

20 20 Cure speed and properties in UPE applications

21 Summary Intelimer technology provides a robust means of creating latency. Crystalline nature of polymer protects matrix encapsulated products. Sharp polymer melting point (switch temperature) promotes efficient catalyst release / exposure. Released / exposed catalyst performs as expected Demonstrated by cure speed and final cure properties in the epoxy and UPE applications Structure-property relationships can be used to design latent catalysts that will fulfill specific application needs. 21

22 Acknowledgements Thermoset Resin Formulators Association Applied Technology, Air Products and Chemicals Inc. Applied Technology, Landec Corporation Presented at a meeting of the Thermoset Resin Formulators Association at the Hilton Suites Chicago Magnificent Mile in Chicago, Illinois, September 15-16,

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