Laser generated air contaminants released during laser cutting of fabrics and polymers

Abstract

Environmental monitoring was conducted at an industrial facility to qualitatively identify the major contaminants generated while cutting fabrics and polymers with a 25 W CO2 continuous beam laser. Carbon monoxide, hydrogen cyanide, and particulates were also assessed, and a bulk sample of residue from the laser exhaust duct was analyzed for inorganic acids, pH, and volatile organic compounds. Samples were collected while cutting vinyl, acrylics, woven fabrics, felt, Formica(4', and Plexiglase) . The laser parameters were standardized to allow for meaningful comparison of results for each target material. The volatile organic compound samples were collected in multibed sorbent tubes with subsequent analysis via thermal desorption and gas chromatography/mass spectroscopy. Depending on the material being cut, a wide variety of compounds were detected. The highest relative concentrations of volatile compounds were found during laser cutting of felt fabrics. The lowest concentrations and fewest number of compounds were from woven fabrics. The compounds detected included hydrochloric acid, aldehydes, benzene, vinyl chloride, various acrylates, acrylonitrile, acetonitrile, styrene, furans, phenol, and butyl cellosolve. Methyl methacrylate was a significant peak detected during the laser cutting of acrylic ester polymers, Plexiglass, and polyvinyl chloride with adhesive backing. Carbon monoxide was not detected above background (2 ppm) during any of the laser cutting trials. Hydrogen cyanide was detected during the laser cutting of felt (15 ppm) and Formica® (8-10 ppm). Particles 0.3 pm in diameter (p Ind) generated during the laser cutting exceeded background particle levels by a factor of ten or more. Most compounds detected in the thermal desorption air samples were also detected in the bulk sample, and the residue was acidic (pH = 3). Area samples collected outside the laser enclosure suggested the local exhaust ventilation system sufficiently contained the air contaminants.

Characterization of Emissions from Carbon Dioxide Laser Cutting Acrylic Plastics

“…As a result of this study, it was determined that the fume extractor was efficient at capturing the gas emissions produced from the laser cutting PMMA material, but not the particulates such as microplastics. Previous studies had reported concern about MMA emission, yet our results revealed the MMA emission was close to the detection level, showing that the fume extractor was efficient at capturing the chemical gases. , The opening of the lid resulted in high peak concentrations of fine and ultrafine particulate matter, which could deposit deep into the lungs and might contribute to potential health problems. Previous studies had shown that particulate emissions for laser cutting PMMA were not as high as other types of plastics, yet there was still a significant increase found even after the usage of the fume extractor. , The amount of particulate matter released would vary on factors such as the cut time and design, and more research would be needed to determine which cut style may produce the highest concentration of particulates.…”

“…The above study does not make reference to the total concentration of particulates and chemical emissions at various parts of the laser cutting process, which would be important to note in order to develop a more efficient control measure. Another study by Kiefer and Moss found that laser cutting PMMA generated particles within a 25 W CO 2 laser cutter enclosure that was more than 10 times the measured background levels . This study focused on the LGACs produced within the enclosure of the laser cutter but does not refer to the total concentration that escapes from the lid during various phases of the laser cutting process.…”

Ion Mobility Spectrometry of Gas-Phase Ions from Laser Ablation of Solids in Air at Ambient Pressure

“…Other studies show that some materials, including plastic, may produce a complex response because laser cutting creates a vapor mixture of aldehydes, benzene, vinyl chloride, acrylates, acrylonitrile, acetonitrile, styrene, furans, phenol, and butyl Cellosolve. 21 Aerosols formed during ablation 21 could lead to spectral distortions, persistence contamination, or quenched response and were removed in prior IMS measurements using particulate filters; filtered vapors were then ionized by chemical reactions. 16 Alternatively, aerosols might also be eliminated by ventilation of the drift tube with a counterflow of drift gas so that ions pass into and through the drift tube while unreacted neutrals and particulate are swept from the drift tube.…”

HETA 99-0109-2754, VideoJet Systems, International, Wood Dale, Illinois.

“…These compounds were also among the major compounds identified in a previous study that evaluated LGAC formation from the laser cutting of PVC with a CO 2 laser. 11 Similarly, PAHs such as naphthalene have been previously detected during CO 2 laser processing of PVC.…”

“…Information concerning LGAC formation is much less complete, although some data is available. 8,9,10,11,12 Predicting the composition and quantity of LGACs that may be generated during any laser situation is not possible. However, it is known that toxic airborne contaminants can be liberated from materials such as plastics, composites, metals, wood, etc., when the target irradiance (power per area) reaches a given threshold, beginning at about 10 3 W/cm 2 .…”