Grantee Research Project Results

Final Report: Safer and Effective Solvents for Paint Stripping

EPA Grant Number: SU836780
Title: Safer and Effective Solvents for Paint Stripping
Investigators:
Institution: University of Massachusetts - Lowell
EPA Project Officer: Page, Angela
Phase: I
Project Period: September 1, 2016 through August 31, 2017
Project Amount: $14,840
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2016) RFA Text |  Recipients Lists
Research Category: P3 Awards , P3 Challenge Area - Chemical Safety , Sustainable and Healthy Communities

Objective:

Methylene chloride is a widely used component for paint stripping products. The three major use categories are industrial use (e.g., in a permanent stationary technical installation), professional use (e.g., by a tradesman), and consumer use (e.g., by a homeowner for do it yourself activities). Methylene chloride is highly volatile and the primary route of exposure is inhalation. There have been numerous occupational and consumer deaths during paint stripping operations resulting from acute methylene chloride poisoning, with at least 56 accidental exposure deaths linked to methylene chloride since 1980. Methylene chloride can cause acute and chronic effects on the central nervous system. The inhalation of methylene chloride can result in short-term effects such as dizziness, clumsiness, headache, nausea, and numbness of fingers and toes, and long-term effects such as loss of concentration, memory loss, and personality changes. Further, methylene chloride is classified as “reasonably anticipated to be a human carcinogen" by the U.S. National Toxicology Program. Consequently, there is increasing demand for paint stripping products that do not contain methylene chloride. Several commercially available products do not contain methylene chloride; however, their paint stripping performance is significantly below that of methylene chloride, and the replacement chemicals, such as N-methyl-2-pyrrolidone (NMP), introduce other environmental, health, and safety hazards. The objective of this research is to identify and evaluate alternatives to methylene chloride that have equal or better paint stripping performance and do not introduce any significant environmental, health, and safety hazards. The primary functional requirements that would need to be satisfied for a solvent blend to replace methylene chloride in a paint stripping product are the following:

1. Coating stripping performance comparable or equal to methylene chloride – less than 15 minutes.
2. Efficacy across a wide range of coatings: paints (oil, latex), varnishes, lacquers, shellacs, epoxies, polyurethanes, and marine finishes.
3. Effective on the following substrate materials: wood, metal, and masonry.
4. Non-flammable.
5. Volatile organic compounds (VOC) content less than 50%.
6. Raw material cost less than $0.70 per pound or less than $5.00 per gallon.
7. Will not stain wood or raise the wood grain.
8. Be comprised of chemicals that are safer from an environmental, health, and safety standpoint as compared to methylene chloride.
9. Be composed of chemicals that have small molecular volumes so that they can penetrate the various polymer coatings (similar or close to the methylene chloride molecular volume of 64.4).

The scope of work for the multidisciplinary team was the identification of solvent blends that have comparable or better solvency characteristics than methylene chloride for various paint coatings. The team used the Hansen Solubility Parameters in Practice software tool to identify solvent blends with the desired solvency parameters (diffusion, polarity, and hydrogen bonding). The new solvent blends identified then were evaluated for environmental, health, and safety issues, as well as commercial availability and cost. The solvent blends then had technical performance testing for paint stripping efficacy on various substrates and coatings at the TURI Laboratory. The final validation testing of the solvent blends will take place at Belcastro Furniture Restoration. However, because the formulations do not yet have the chemical additives, the full functionality of a complete paint stripping formulation will not be covered in Phase I.

Summary/Accomplishments (Outputs/Outcomes):

Performance testing for a variety of coating materials on wood, masonry, and metal substrates showed that the new solvent blends, comprising various combinations and amounts of methyl acetate, dimethyl sulfoxide, and thiophene, worked comparably to methylene chloride-based paint strippers and significantly better than other existing alternatives based on chemicals such as NMP, benzyl alcohol, and dibasic esters. Having used a successful methodology based on Hansen Solubility Parameters for identifying safer and effective solvent blends, the research team is optimistic that other toxic solvents used for various consumer and industrial products can be replaced with safer solvent blends.

Conclusions:

The use of the Hansen Solubility Parameters-based approach is an efficient method to identify safer and effective alternatives to methylene chloride and NMP in paint stripping products.

Journal Articles:

No journal articles submitted with this report: View all 5 publications for this project

Supplemental Keywords:

green chemistry, paint stripping, methylene chloride, toxics use reduction, N-methyl-2-pyrrolidone, environmental health, alternatives assessment, formulations, Hansen Solubility Parameters