Tagawa Yumiko

The detergency of polyethylene terephthalate (PET) films in an aqueous solution was investigated using a commercial ultrasonic cleaning apparatus operating at 38 or 130 kHz. Carbon black (CB) or colored oleic acid (OA) were deposited onto the PET film. The PET film was ultrasonically cleaned in an aqueous sodium chloride (NaCl) solution with or without sodium hydroxide (NaOH) or sodium dodecyl sulfate (SDS). The detergency was calculated using the microscopic image analysis system. It was found that CB detergency at 38 kHz was higher than that at 130 kHz for the same electric power. Ultrasonic washing was also carried out using PET fabrics and the detergency was evaluated by the surface reflectance method. The detergency was found to enhance in the presence of NaOH and SDS. The effect of the exposure direction of the ultrasonic wave on the fabric detergency and uneven washing was investigated using a self-developed ultrasonic cleaning apparatus operating at 38 kHz.

<p>The detergency of polyethylene terephthalate (PET) films in an aqueous solution was investigated using a commercial ultrasonic cleaning apparatus operating at 38 or 130 kHz. Carbon black (CB) or colored oleic acid (OA) were deposited onto the PET film. The PET film was ultrasonically cleaned in an aqueous sodium chloride (NaCl) solution with or without sodium hydroxide (NaOH) or sodium dodecyl sulfate (SDS). The detergency was calculated using the microscopic image analysis system. It was found that CB detergency at 38 kHz was higher than that at 130 kHz for the same electric power. Ultrasonic washing was also carried out using PET fabrics and the detergency was evaluated by the surface reflectance method. The detergency was found to enhance in the presence of NaOH and SDS. The effect of the exposure direction of the ultrasonic wave on the fabric detergency and uneven washing was investigated using a self-developed ultrasonic cleaning apparatus operating at 38 kHz.</p>

Cleaning power of different surfactants was investigated using a model detergent system consisting of a PET film and stearic acid. Surfactants used were alcohol ethoxylates (AE, C12) and methyl ester ethoxylates (MEE, C12) with different ethylene oxide (EO) chain lengths. For comparison with these nonionic surfactants, anionic surfactant, sodium alkyl sulfate (AS, C12), was chosen. After depositing stearic acid, the PET film was cleaned in aqueous surfactant solutions by applying stirring as a mechanical action for soil removal. The amounts of stearic acid deposited on the PET film before and after the cleaning were obtained by binary processing of microscopic images of the PET film surface, from which the removal efficiency was calculated. The surface tension gamma and the contact angle on the PET film theta of the surfactant solution were measured by the pendant drop and the sessile drop method, respectively. For the nonionic surfactants, critical micelle concentration, cmc, and gamma and theta above cmc decreased with decreasing EO chain length. The removal efficiency of stearic acid increased with increasing surfactant concentration and further increase in the removal above cmc was observed in the cases of AE and MEE with EO chain length of 10. The removal efficiencies obtained in all systems had good relation with both gamma and theta, indicating that the penetration of the surfactant solution between stearic acid and the PET film in the contact zone was a dominant factor in the soil removal in the present system.