Grantee Research Project Results
Final Report: A GREEN AND UNIQUE THERMOSETTING-THERMOPLASTIC POLYCARBONATE
EPA Contract Number: 68HERD19C0006Title: A GREEN AND UNIQUE THERMOSETTING-THERMOPLASTIC POLYCARBONATE
Investigators: Cameron, Randy E.
Small Business: Instrumental Polymer Technologies, LLC
EPA Contact: Richards, April
Phase: II
Project Period: December 1, 2018 through November 30, 2020
Project Amount: $300,000
RFA: Small Business Innovation Research (SBIR) - Phase II (2018) Recipients Lists
Research Category: Small Business Innovation Research (SBIR) , SBIR - Manufacturing
Description:
The purpose of this project was to develop a new class of plastics we call thermosetting thermoplastic. There are 300 million tons of plastics used to form structural materials, composites, adhesive and sealants. Manufacturers have to choose between using a thermoplastic or thermosetting plastic. Thermoplastics are long chained polymers that can easily melt processed, but the resulting material is susceptible to solvent attack and deforms under stress. If more structural integrity and chemical resistance is needed, a thermosetting plastic is chosen in which polymer segments react together to form a crosslinked matrix. The problem is thermosets are more costly to process. The precursor reactants need to be separated, cooled or blocked to keep them from reacting before processing. Energy in the form of heat or light is then needed to activate the cure. Furthermore, the crosslinking of a thermoset is irreversible. Currently both thermoplastics and thermoset plastics are derived from petroleum byproducts and can last 100 years before biodegradation. Though there is significant effort to recycle thermoplastics, of the 33.6 million tons of plastic discarded only 9.5% of it is recycled.
In this project we developed an aliphatic polycarbonate that will be a benefit for both the manufacturer and for the environment. This thermosetting thermoplastic is a crosslinked thermoset resin at room temperature, but when heated over 120°C, the polymer network fragments into a low viscosity liquid that can be easily processed. Upon cooling the material once again crosslinks. This provides a wide range of cost savings for those using thermoset resins. It also provides better chemical resistance and structural integrity for those who use thermoplastics. This thermosetting plastic can also be recycled like a thermoplastic. Furthermore, this technology is made from sustainable raw materials and will biodegrade faster than current plastics.
This thermosetting thermoplastic technology is a foundation technology with a wide range of potential applications. The fundamental technology was demonstrated in a Phase I SBIR program. During this Phase II project we used this technology to develop a thermosetting thermoplastic injection moldable resin system, a low temperature cure powder coating system, a low viscosity and low temperature processable hot melt coating and adhesive system, a single component moisture cure system, and a low temperature cure baking enamel. All of these thermosetting polymer systems will be a cost benefit to the customers while also being a benefit to the environment and will pave the way towards replacing petrochemically-derived polymers.
Summary/Accomplishments (Outputs/Outcomes):
During Phase II of this program we were not only able to demonstrate the technical soundness of this technology, but found that it would form a broader application platform than we had expected. Though we synthesized both dendrimeric and hyperbranched versions of the polycarbonate polymer, the dendrimeric versions almost always had the advantage of lower viscosity and faster cure. Samples prepared with reactive hydroxyls on their backbone crosslinked to form a solid resin upon cooling to room temperature, as expected. Those samples were found to have excellent chemical resistance. Upon heating to 120°C the crosslinked polymer fragment to form a liquid that can be processed and shaped, as expected. Upon cooling those samples once again crosslinked, suggesting the technology could be used as a recyclable thermoset resin. If ground within 24 hours in to a powder, the powder could be used as a low temperature cure powder coating. When melted it formed a low viscosity liquid that could be spray applied as a hot melt coating. If applied between two substrates it could be used as a hot melt adhesive.
We also demonstrated that samples prepared without reactive hydroxyls on their backbone, and only 6-membered cyclic carbonates as reactive groups, remained liquid at room temperature until exposed to moisture in air. The moisture in the air initiated a ring opening polymerization cure. We have demonstrated that this one component coating system could offer the same performance properties of two component polyurethane coatings. It also offers better UV durability. This cyclic carbonate terminated polymer systems could also undergo ring opening polymerization when exposed to heat for a very short time, revealing this technology could be ideal in coil coatings.
We performed physical testing on the various forms of the cured materials after crosslinking and found them to have excellent strength, chemical resistance and adhesion. In order to achieve high elongation and strength for use as an injection moldable polymer system, we synthesized and inserted an aliphatic polycarbonate diol in to the thermosetting thermoplastic system. The polycarbonate diol was designed to use only sustainable raw materials in its source. Such a system showed promise for competing against commercially available polycarbonate thermoplastic, thermoplastic polyurethane or thermoplastic elastomers.
Conclusions:
The commercial applications for the hydroxyl terminated and cyclic carbonate terminated polycarbonates developed in Phase II are low temperature curing powder coatings, hot melt coatings and adhesives and composites, coil coatings, moisture cured coatings and baking enamels.
This technology is a broad platform from which a wide range of markets can be entered. The environmental benefit is that in every market described below it will be displacing a plastic made from petrochemically derived, and often toxic, raw materials with a sustainable, safe and biodegradable plastic. But in every market it will also offer a cost advantage to the customer. IPTECH already sells in to all of these markets, so our same distribution and sales network can be utilized.
1. Low Temperature Cure Powder Coatings - Powder coatings are thermosetting systems that are ground into powder and electrostatically sprayed on to surfaces. The appliance is then heated so the powder melts and cures to form a relatively thick protective coating. Most powder coatings need to be cured at 200°C for 10-30 minutes, which makes them unsuitable for many applications. This is a large market (currently ~$9 billion). Our technology is an advantage by curing at only 120°C, saving the customer money (energy) and allowing them to apply the coating on a wider range of substrates.
2. Single-Component Moisture Curing Coatings - Currently the 2-component polyurethane coatings are used for high performance applications like the exterior coatings of automobiles, aircraft and yachts. Due to the short pot life of these systems there is a significant amount of material and economic waste. A variation of out thermosetting thermoplastic technology was developed during this project that is a one component moisture curing system and yields a coating with competitive physical performance of commercially available 2-component polyurethane systems. UV-durability was proven to be a particular advantage as was the fact that it has excellent adhesion to metal, so an epoxy primer is not necessary.
3. Coil Coatings and Baked Enamels - A variation of this technology, was found to be an ideal single component system that cures quickly with heat, which makes it marketable for use as a coil coating or industrial baked enamel. The advantage of this technology is a lower temperature bake and excellent adhesion directly to the substrate.
4. Hot Melt Coating - A variation of this technology was proven to be useful as a hot melt coating. There are many applications for thick (>20mil) adhesive 100% solids coatings to be applied over metal or concrete. This application ranges from roofing to coating of tools. The advantage of our system is its low viscosity so it will flow out well and its ability to adhere directly to the substrate.
5. Hot Melt Adhesives (HMA) - The same coating used as a hot melt coating can also be used as a hot melt adhesive. This is a very broad market in which a hot, liquid thermoplastic is applied to a substrate to make it adhere to another. This technology is an advantage to solvent based or water based adhesives, because solvent or water aren't trapped between the two surfaces. There is also no shrinking of the adhesive away from the substrates. It's also an advantage over two component adhesives because the application is easier and there is less waste. Because of their ease of application, most adhesives would be HMAs if this technology would simply provide better adhesion. HMAs are generally used to bond metals, glass, wood, plastic and rubber. There are two different heat ranges, low temperature guns are usually at 120°C whereas high temperature guns are at 190°C-200°C. This same technology will be able to be utilized in composites and fiberglass in which the reworkability (the ability of this technology to fragment and melt upon heating) will be a huge advantage.
6. Injection Molded Plastic - In this market thermoplastic plastic is generally used. Of all the markets listed above, this is the largest, estimated at $162 billion. We have already been in touch with current manufacturers of thermoplastic elastomers who see this technology as a means of increasing the chemical resistance and performance of thermoplastic elastomers.
SBIR Phase I:
A Green and Unique Thermosetting-Thermoplastic Polycarbonate | Final ReportThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.