Final Report: Soy-Capped Polycarbonate Dendrimers for Tough, Sustainable Water Based Wood Coatings

EPA Contract Number: EPD13020
Title: Soy-Capped Polycarbonate Dendrimers for Tough, Sustainable Water Based Wood Coatings
Investigators: Cameron, Randy E.
Small Business: Instrumental Polymer Technologies, LLC
EPA Contact: Manager, SBIR Program
Phase: I
Project Period: May 13, 2013 through November 14, 2013
Project Amount: $80,000
RFA: Small Business Innovation Research (SBIR) - Phase I (2013) RFA Text |  Recipients Lists
Research Category: Small Business Innovation Research (SBIR) , SBIR - Innovation in Manufacturing

Description:

The purpose of this research was to develop low-cost and sustainable nanotechnology that can replace unsustainable and environmentally toxic, oil-based alkyd resins currently used in the large wood furniture and architectural coatings markets. Ironically, oil-based paint, though derived from natural oils, has evolved through time to contain an unsustainable polyester backbone and requires a large amount of solvent for dissolving the high viscosity resins as well as for cleanup. An oil-based resin technology is needed that has the performance of oil-based paints, requires little or no solvent and can be cleaned with water. The cost needs to be low enough to compete with current alkyd resin technology. Though such a technology would have the potential of creating a new trend for all wood and architectural coatings, it is a specific response to paint companies who have contacted Instrumental Polymer Technologies, LLC (IP TECH), in need of lowering the amount of volatile organic components (VOCs) in their oil-based paints. There is a growing trend for U.S.-based furniture manufacturers to bring their manufacturing back to the United States as a result of increased labor costs overseas and increased shipping costs for bulk goods. For the last half-century, these products have been painted in countries with little or no environmental regulation, and these furniture manufacturers, who are building or expanding their facilities in the United States, are scrambling to obtain oil-based wood coatings that can help them meet EPA regulations for solvent emissions.
 
Despite the cost competitiveness of these types of coatings, the answer to this issue is nanotechnology. The goal of this project has been to use IP TECH's proprietary dendrimeric aliphatic polycarbonate technology to produce high molecular weight dendrimers with a tough polycarbonate core and with soyate groups, derived from methyl soyate (common biodiesel) attached to their surface. The spherical nature of these “dendryds” would give them a much lower viscosity than current alkyd paint, therefore allowing them to use much less solvent. IP TECH also incorporated amino acid groups into the core of the dendryds to make them water dispersible so the solution would be cleaned with water. The company would use sustainable raw materials, including methyl soyate and amino acids, attached to a sustainably derived polycarbonate core to create this unique type of nanotechnology at a cost competitive with current alkyd paint.

Summary/Accomplishments (Outputs/Outcomes):

IP TECH was able to form the dendrimers by using pentaerythritol and capping them with soyate and glycine. The best method was to prereact the pentaertythritol with the methyl soyate (biodiesel) and then perform the polymerization process, evolving the polymer into its dendrimeric shape. The glycine was added on the polymer in a last step.
 
The dendrimers were low viscosity and yielded coatings with excellent properties. They easily could be dispersed in water for cleanup. These are the first resins formed that are low enough viscosity for direct application as a coating but also can be dispersed in water for cleanup, showing the unique features of dendrimer technology for the coatings market.
 
The performance and the drying time of the dendrimers could be improved further by blending a small amount of more linear dendrimer (polymer which did not go through the evolution process) into the dendrimeric material.
 
With respect to answering the questions we posed at the beginning of this program:
  1. What is the best method for making the core large enough to offer unique toughness in the cured dendryd?  IP TECH found that methanol is necessary during the initial polymerization to make the PE miscible with the DMC. The methanol is easily removed at the end, and the methanol distillate from a previous reaction can be used for the subsequent reaction. With respect to building the highest molecular weight with the most spherical shape, the company found that a stepwise process in which the DMC is added in three aliquots is the best procedure.
  2. Can the dendryds be formed with a spherical nature to give them low viscosity and excellent flow and wetting so they can permeate into wood? Yes. The viscosity drops during the incubation period with very little drop in average molecular weight, suggesting that the polymers are becoming less entangled and more spherical in nature. The important point is that the viscosity is low enough that the material gets excellent adhesion to wood while being only 90% solids.
  3. Can carboxylate functionality in the core offer water dispersibility for the dendryds? Yes, though IP TECH needed to change the method for derivatizing the dendrimers with glycine; the resulting material is completely dispersible in water even though the viscosity is low enough for direct applicability.
  4. Will the fatty groups on the exterior of the dendrimer offer excellent wetting and flow so that flow and wetting agents are not needed? Yes. The dendrimers act very much like a surfactant and wet out very well over metal, wood and plastic substrates.
  5. Will the carboxylates being in the core, but the crosslinking fatty groups on the surface, offer stain and water resistance? Yes. The wet adhesion and the water drop staining resistance were excellent.
  6. Will the very high functionality of soy groups on the surface ensure fast and thorough cure so toxic drying agents are not necessary? The cure was fast enough to be marketable; however, it was dramatically improved using a small amount of a more linear version of the same polymer blended with the dendryds.
  7. Will the high functionality of soy groups and ease of manufacturing keep the cost of the dendryd competitive with alkyds? Yes. As shown below, even with costing from a 500-gallon reactor, which is small in the business, the cost is only $1.43. Considering most alkyds, which are only 60 percent solids in solvent, are $1.75-2.50/lb, this technology is very competitive with current alkyd technology.

Conclusions:

During this project, IP TECH was able to demonstrate the production of polycarbonate dendrimers that are covered with soyate groups and that contain the amino acid glycine for water dispersibility. The resulting dendrimers had very low viscosity and could be applied as a coating without use of solvent. The material could be dispersed into water but also could be cured into a film. The company found that the synthesis of the dendrimer, using its evolution polymerization process, needed to begin by prereacting two ingredients, and it was best to add one of the reactants in aliquots. IP TECH optimized the amount of glycine in the core of the dendrimer so it could balance the viscosity of the material, dispersibility of the dendrimer and toughness of the resulting coating. The company also found that a combination of the spherical dendrimers, with a more linear version of the same polymer, yielded better cure and performance properties.

Supplemental Keywords:

VOC, polymers, dendrimers, green chemistry, biodiesel

SBIR Phase II:

Soy-Capped Polycarbonate Dendrimers for Tough, Sustainable Water-Based Wood Coatings