VOC Emission Control Solutions for Injection Molding

Injection molding generates VOCs mainly from resin heating, release agents, and cleaning solvents. These emissions affect environmental compliance and workplace health, violating strict standards such as China’s GB 37822-2019 and the EU’s REACH regulation. For manufacturers, unregulated VOC emissions can lead to fines, production suspensions, and damage to brand reputation. This article provides a practical control plan covering source reduction, process control, end-of-pipe treatment, and daily management to achieve stable and cost-effective compliance, suitable for small, medium, and large injection molding enterprises.

Source Reduction

The most effective way to lower VOC emissions is to reduce generation at the source, which is also the most cost-effective method with no need for large equipment investment. Use low-VOC, low-odor raw materials and limit recycled resin content to ≤30% to avoid excessive volatile release—recycled plastics that have undergone multiple melting cycles are more prone to thermal degradation, releasing significantly more VOCs. Replace oil-based release agents and strong solvents with water-based, solvent-free alternatives: water-based release agents have a VOC content ≤5%, compared to ≥60% for traditional oil-based ones, which alone can reduce auxiliary VOC emissions by over 85%. Optimize barrel temperature and residence time to reduce thermal decomposition of resins, which directly cuts VOC output: for PP, lower the melting temperature from 220℃ to 205-215℃; for ABS, reduce from 240℃ to 230-235℃, and shorten melt residence time in the barrel to 3-5 minutes to avoid overheating.

Process Control

Most VOCs in injection molding escape as unorganized emissions, which account for 40-60% of total emissions and are difficult to control if not addressed properly. Proper sealing and targeted collection can greatly improve control efficiency. Seal injection barrels, nozzles, and hoppers with high-temperature resistant gaskets to prevent VOC leakage during processing. Install local fume hoods directly above each injection machine nozzle—positioned 15-20cm above the nozzle with a wind speed of 12-15 m/s—to capture emissions efficiently, ensuring a collection rate of ≥90%. Maintain slight negative pressure (5-10 Pa) in the workshop to avoid VOC accumulation and escape through doors, windows, or gaps. Separate storage, cleaning, and production zones to prevent cross-contamination: store auxiliary materials in a sealed warehouse, and conduct mold cleaning in a closed area with a local gas collection device.

End-of-Pipe Treatment

Collected VOC exhaust is typically low concentration and large volume, requiring efficient, stable treatment processes to meet emission limits. For small and medium factories with limited budgets, activated carbon adsorption is economical and reliable, achieving a treatment efficiency of ≥95%. Choose honeycomb activated carbon for its large adsorption capacity and long service life, and regenerate saturated activated carbon at 120-150℃ for reuse to reduce operating costs. For larger facilities or those with stricter environmental requirements, zeolite rotor concentration plus catalytic combustion is recommended: the zeolite rotor concentrates low-concentration VOCs into high-concentration gas, reducing treatment volume, and catalytic combustion oxidizes VOCs into harmless carbon dioxide and water at 250-350℃. Both systems can meet the national standard of NMHC ≤ 6 mg/m³, and installing online monitoring devices ensures real-time tracking and regulatory compliance.

Management and Maintenance

Stable VOC control requires standardized management to ensure the long-term effectiveness of control measures. Establish clear operating procedures for environmental protection equipment, specifying the operation, inspection, and maintenance requirements for each component. Conduct regular inspections and maintenance: check activated carbon or zeolite rotor status monthly, replace faulty heating or collection components promptly, and clean the duct system to avoid blockages. 

Train operators on VOC control knowledge and correct operation of equipment, enhancing their environmental awareness. Perform periodic third-party testing to verify emission levels, and keep complete records of equipment status, maintenance, and testing results to support internal management and official environmental inspections.

Conclusion

A comprehensive VOC control system combines source reduction, process containment, efficient end treatment, and strict management. By choosing appropriate technologies based on factory scale and emission characteristics, manufacturers can achieve consistent compliance, improve the workshop working environment for operators, reduce operational risks such as fines and production suspensions, and realize sustainable development in injection molding production.