Automotive Coatings Phase Out TBAc and pCBtF
The South Coast Air Quality Management District (SCAQMD) approved amendments to the rule for Automotive Coatings (Rule 1151). Rule 1151 – Motor Vehicle and Mobile Equipment Non-Assembly Line Coating Operations phased out two solvents currently exempt from the definition of a VOC that have been determined to have toxic endpoints: para-chlorobenzotrifluoride (pCBtF) and tert-butyl acetate (TBAc). However, Rule 1151 created new mandates, and RadTech opposed the requirements on the UV/EB/LED industry. The association contended that UV/EB/LED processes are all electric, eliminating the need for add-on control devices and thereby preventing emissions of criteria pollutants. It argued that since these products are not formulated with conventional solvents and, therefore, the emissions of Volatile Organic Contaminants (VOCs) are negligible, they should not be subjected to the same level of scrutiny. Additionally, the rule made no mention of energy-curable materials (no definition included) and left out the RadTech test method for UV/EB/LED thin films (ASTM D-7767-11).
The district did include UV/EB/LED technology in its technical analysis. The report stated, “Ultraviolet, electron beam, light-emitting diode (UV/EB/LED) technologies have the potential to reduce VOC emissions from coatings, although these technologies are not widely implemented in automotive coatings at this time.” The fast cure rates of UV/EB/LED curable primers were recognized by SCAQMD’s staff report, which identified a UV/EB/LED-curable primer formulated at approximately 210 g/L, which is well below the current 250 g/L limit for primers. The district also acknowledged that one of the control measures for coatings and solvents in its Air Quality Management Plan (CTS-01) “could also result in the use of ultraviolet (UV)-cured resins and coatings, which would not be expected to use water or generate wastewater.” The agency reported that several major coating manufacturers currently offer UV-curable primers as part of their product portfolios with a VOC content of approximately 200 g/L. RadTech is collaborating with other organizations in order to get the word out about these new mandates.
Rules Bundle for Wood, Aerospace, Metal Coatings
In an unprecedented proposal, SCAQMD proposes to amend Rule 1136 – Wood Products Coatings, Rule 1107 – Coating of Metal Parts and Products and Rule 1124 – Aerospace Assembly and Component Manufacturing Operations. The district surveyed coatings manufacturers in August 2024 to assist staff in understanding “the extent to which para-ChloroBenzotriFluoride (pCBtF or Oxsol 100) and tertiary-Butyl Acetate (TBAc) are used to formulate compliant products.” Results will be used to assist staff in evaluating Volatile Organic Compound (VOC) content limits and proposing pCBtF and TBAc prohibition timelines.
Staff announced that, due to staffing resources, the rule development for the wood industry will resume second quarter 2025. According to survey responses, 32% of products use pCBtF in wood coatings formulation, while none use TBAc. Rule 1107 (Metal Coatings) currently regulates 22 types of coatings. Coating manufacturers reported that of those, the main ones sold into the South Coast Basin are General One-Component; General Multi-Component; Heat-Resistant; Metallic and High-Temperature. Staff plans to continue rule development under the assumption that pCBtF and TBAc “can be phased out of these categories with no issues.” According to staff, initial survey data indicates the General One-Component coating category contains ready-to-use alternatives to pCBtF and/or TBAc , but more analysis is needed for General Multi-Component, Heat-Resistant and Metallic coatings.
Rule 1124 establishes VOC limits for materials used in the aerospace industry. Current VOC limits range from 50 to 1,000 g/L, depending on the product category. Manufacturers reported that a total of 349 aerospace products are sold in SCAQMD. The sales volume reported was as follows: Primers: 94 products, ~29,500 gallons; Top Coatings: 60 products, ~13,300 gallons; Adhesives: 82 products, ~1,800 gallons; and Sealants: 113 products, ~ 8,900 gallons.
Some of the primers, top coats and sealants are formulated with pCBtF, while TBAc was found only in top coats. SCAQMD reported that 29,000 gallons per year of General primers are sold in the district. Only a fraction (1,600 gallons) are free of pCBtF or TBAc. Staff believes that TBAc is not widely used in aerospace materials sold in the SCAQMD and that an early prohibition date would be feasible. Staff’s assumption that pCBtF is not needed to comply with VOC limits for maskants, lubricants, cleaning solvents and strippers was met with resistance from representatives of aerospace companies.
The proposal is likely to include a “sell-through” provision to allow coating manufacturers time to sell products manufactured prior to prohibition date that already are in the supply chain and a “use-through” allowance to give end users time to use remaining products purchased before the prohibition takes effect. The proposals are expected to reach the final stage sometime in 2025.
Rita Loof
director of regional environmental affairs, RadTech International North America
[email protected]
