Recycled Latex Paints as Raw Materials for Thermoplastics-Processing and Products

AMIPP Advanced Polymer Center
Rutgers University
Piscataway, New Jersey 08854-8065
&
Solid Waste Policy Group
Rutgers University
New Brunswick, NJ 08901
&
National Council on Paint Disposition
PO Box 74
East Brunswick, New Jersey 08816

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2005 Research Proposal

Recycled latex paints as raw materials for thermoplastics - processing and products

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Investigators:
Richard Lehman
Thomas Nosker
Priscilla Hayes
Marv Goodman

Recycled latex paints as raw materials for thermoplastics - processing and products
By
Richard Lehman
Thomas Nosker
Priscilla Hayes
Marv Goodman

EXECUTIVE SUMMARY

Research at Rutgers University during 2004 showed the feasibility of reusing waste latex paint as a raw material for thermoplastic polymer composites. A project is proposed to commence in 2005 that will seek to move this technology toward commercialization via a three-pronged approach. First, additional engineering data will be collected so that a comprehensive materials technical spec sheet can be prepared for dissemination to industry. Processing technology will be developed to enable the water-rich paint slurries to be reduced to polymer/ceramic solids while simultaneously being thermoplastically mixed with other polymers to produce a high value moldable feedstock for a variety of products produced by industry. Thirdly, a product development phase, focused on a targeted initial commercial product, will be conducted to match up material properties with promising end-use applications. The project will last one year and will cost $131,676.

BACKGROUND

A large amount (~34 million gallons) of leftover waste latex paint is generated each year from a variety of sources, including the incorrect tinting at the wholesale/retail formulation level, residual paint at the consumer level, and from a variety of other instances that generate paint not suitable for use. Some of this paint, principally the light color mistints from large retailers such as Home Depot, can be returned to the manufacturing process. Other paints may possess value in export markets. A large residual amount cannot be used as paint and must either be disposed in suitable landfills or directed to alternative uses. A variety of alternative uses have been investigated that include acrylic caulk, aggregate, and sealants.

A feasibility study conducted during 2004 in the AMIPP Advanced Polymer Center focused on using leftover latex paint as a raw material for the formulation of thermoplastics. The motivating concept for this initial study was the three-fold value envisioned in this waste material: the acrylic polymer, the inorganic filler, and the highly dispersed state of the micro/nano fillers. These three elements have significant value in the formulation of plastics and plastic composites and the goal of the 2004 work was to assess the feasibility of using leftover paint as a plastics raw material. The results of this successful initial study are presented in a report dates October 15, 2004.

Based on the success initial work, a second phase of work is proposed to extend the initial work and move the technology closer to commercialization.

OBJECTIVES

• To extend the feasibility study results to a wider range of engineering properties
• To develop processing technology for the conversion of the wet latex paint to dehydrated polymer and polymer/ceramic mixtures suitable for injection molding and similar processes.
• To assess and develop product based technologies for the reclaimed materials.

METHOD

Extension of Property Study
A small initial segment of the proposed work will serve to reconfirm the results of the feasibility study and to extend the property results presented in the October 15, 2004 report. Specifically, a major value element for the latex paint waste combined with HDPE and PMMA was identified with regard to achieving high modulus, good ultimate strength, and enhanced strain to failure. Toughness may also be improved via the incorporation of micro/nano particles [titania and extenders] in the polymer matrix along with the combination of paint polymers [low Tg acrylics] and HDPE or PMMA. Although the feasibility study showed promising results, some additional testing is needed to fully define this array of engineering properties. Polymer Processing Study

In our initial work, paint was dehydrated simply by pouring the latex onto trays and drying the paint in a laboratory oven, a time-consuming process which eliminated some but not all the moisture. Subsequently, the paint was blended with varying levels of virgin polymer and extruded through an open vent port extruder to eliminate more of the moisture and combine the polymers. Finally, the ground extruder output was used as injection molder feed, again with a varying array of virgin polymer additives.

A vastly improved, automated, inexpensive, and scalable process is needed for commercial implementation of this process. The research team has several ideas in this regard that are the subject of development work during the proposal time frame. The core concept consists of using specialized extrusion and other thermal processing technology that permit simultaneous moisture removal with thermoplastic blending of the multi-phase mixture. The AMIPP Advanced Polymer Center possesses a variety of extrusion, compression molding, and injection molding equipment that is well suited for this study. In particular, we recently acquired a state-of-the-art multi-port compounding extruder that will enable us to evaluate the concept of integrated moisture removal and thermoplastic polymer blending.

If this one-step processing approach is successful, as we believe it will be, we will then proceed to consider and design scale up options. Our relationship with a major fabricator of plastic structural component and lumber from recycled plastic waste [Polywood, Inc. of Edison, New Jersey] will be a major asset in developing scale-up technologies and perhaps testing some of our concepts in a manufacturing environment late in this project segment.

Products from reclaimed paint plastics
To maximize the opportunity for utilizing waste latex paint in the near term, product development work must be conducted in parallel with the process development work discussed above. The principal motivation for this parallel action is the numerous hurdles encountered in introducing a new recycled product to the market, as has been experienced in the recycled paper, glass, and metals markets. Principal issues that will be addressed in the product study are:

• Performance suitability. Molded plastic products will be considered that meet the material performance screen based on stiffness, strength, and toughness. Effect of impurities and the comparison of product quality and uniformity over time.
• Aesthetics. Recycled paint plastics will vary considerably in color even with considerable blending of feedstocks. Thus, product selection will focus either on products that are insensitive to color, such as many industrial and outdoor products, or on combining pigments with the reclaimed polymers to reestablished desirable color.
• Volume. High quantities of recycled latex paint are envisioned. Product applications will be considered that have the potential for large material volume, even with low penetration levels. Furthermore, potential users will insist on assurances that a sufficient amount of uniform and quality product is available over time if they are to commit part of their production to this new product.
• "Green Focus". Products and markets that emphasize the use of recycled raw materials and which have an overall "green" focus will be targeted.

Ultimately the goal of this product development effort is two-fold:

1. to develop a pelletized "resin-type" product that can be sold as a commodity to fabricators to use side by side, or in place of, other resins they use today to fabricate a wide variety of products
   
2. to identify a single targeted product for development that the research teams feels is ideally suited to the developed materials and the product/market mix for which it will be used.
   

For Mistints New Way to Turn Pain(t)ful Loss into Retailer's Gain