Tagawa Yumiko

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.

The soil removal behavior from poly(ethylene terephthalate) (PET) films was investigated using a microscopic image analysis system. Carbon black or stearic acid as a model soil was deposited onto a PET film. The PET film was cleaned in various aqueous and non-aqueous solutions by applying stirring or frequency-modulated ultrasound as a mechanical action of soil removal. The amounts of soil deposited on the PET film before and after cleaning were obtained via binary processing of microscopic images, from which the removal efficiency was calculated. Most of the carbon black was deposited on the PET film as submicron aggregates and ultrasound removed them efficiently in a short time, even for relatively smaller aggregates. The removal efficiencies with stirring were less than ca. 10% in all solutions, whereas the removal using ultrasound had high efficiencies that exceeded 80% in the surfactant-free systems. In the case of stearic acid, the removal efficiency with stirring was below 30% in the aqueous solutions, although stearic acid was removed completely in ethanol and n-decane. For ultrasonic cleaning, the removal efficiencies of stearic acid in aqueous solutions became 2-3 times as large as those with the stirring action. To improve soil release in aqueous solutions, the PET film was treated by the dry processing using an atmospheric pressure plasma jet (APPJ) equipment. The wettability and the surface free energy of the PET film were found to increase due to surface oxidation via the APPJ treatment, which resulted in enhanced removal of carbon black and stearic acid in any aqueous solutions. © 2013 by Japan Oil Chemists' Society.

The removal of the carbon black (CB) particles from the polymer substrates was investigated in water/ethanol mixtures. As substrates, the films and the fibrous assemblies of polyethylene, nylon 6 and cellulose acetate were used. The ultrasonic wave was applied as a mechanical action for cleaning. The detergency of the CB particles for the films and the fibrous assemblies was assessed with the quartz crystal microbalance (QCM) technique and the reflectometry, respectively. The detergency for the films was discussed with the wetting force calculated from the experimentally determined contact angle on the substrate and surface tension of the water/ethanol mixture.

The effect of ultraviolet light irradiation on the characteristics of the polyethylene (PE) surface was investigated by the quartz crystal microbalance (QCM) technique. The PE film was prepared on the gold electrodes of the QCM by spin-coating from the solution and then was treated by the excimer UV lamp in ambient air. The changes in the hydrophilic properties, moisture adsorption, and water retention of the PE film due to the UV irradiation were determined from the frequency change of the QCM. To evaluate the detergency of the PE film, stearic acid as model oily soil was deposited onto the PE film formed on the QCM by the Langmuir-Blodgett (LB) technique, and was ultrasonically cleaned in aqueous detergent solutions containing ethanol or surfactant. The removal efficiency obtained from the frequency change of the QCM was found to increase considerably after the UV irradiation. From independently determined contact angles and the surface free energy components of the PE film, the free energy change resulting from the penetration of the detergent solution between stearic acid and PE in the zone of contact was calculated. Good relation was found between the removal efficiency and the free energy change, indicating that the increase in the detergency of the PE surface by UV irradiation was explained by surface energetics.<br>

The detergency of particulate soil in aqueous solutions was examined by the quartz crystal microbalance (QCM) technique and was discussed on the basis of the surface free energies. The gold electrode and spin-coated film of polyethylene, nylon 6 and cellulose triacetate on the gold electrode of the QCM were used as substrates. As model particulate soils, polyethylene and nylon 12 particles were used. The QCM was perpendicularly immersed in aqueous dispersions of spherical particles to deposit the particles onto the substrate. After pulling the substrates out of the dispersion and drying in air, the substrates were cleaned in aqueous solutions with and without ethanol. The removal efficiency was calculated from the frequency changes of the QCM due to soil deposition and cleaning. The efficiency was dependent on the particles and substrates, and increased by the addition of ethanol in all system. The Lifshitz-van der Waals and acid-base components of the surface freed energy of the soil and substrate were estimated from the contact angles of three probe liquids. The detergency phenomenon in the present system was explained in terms of the free energy change due to soil removal, which was calculated from the surface free energy components.

The titled assessment was conducted using a quartz crystal microbalance (QCM) and the Langmuir-Blodgett (LB) method. The gold electrodes of QCM were coated with cellulose acetate, nylon 6 or polyethylene film by spin-coating. Spreading monolayers of long-chain fatty acid as oily contaminants on water were transferred onto spin-coated polymer film. LB films of arachidic acid were ultrasonically cleaned in aqueous solution. Detergency was determined based on the frequency change of the QCM due to cleaning. Detergency was greatest for cellulose acetate, followed by nylon 6 and polyethylene. For all films, detergency increased with the addition of ethanol, surfactant and alkali. Detergency is discussed in relation to contact angle of aqueous solution on polymer film. Liquid introduction between LB film and the polymer surface in the zone of contact appeared to be a significant factor in the removal of LB film from the polymer surface. © 2004, Japan Oil Chemists' Society. All rights reserved.

Soil deposition on fibers was investigated from the standpoint of the waste water treatment. Polyethylene, poly (vinylidene chloride), poly (vinylidene fluoride), polyethylene terephthalate and nylon 6 fibers were used as soil collectors. Following immersion of the fibers in water from Sarusawa pond, water turbidity was measured. Turbidity decreased due to the deposition of soil onto the fiber surfaces. Poly (vinylidene chloride) fibers were more effective as a soil collector than any other fibers.<BR>Particle deposition from an aqueous solution was investigated using a model system consisting of spherical polyethylene or nylon particles and a polymeric plate. The plate was perpendicularly immersed in an aqueous suspension. The number of particles deposited on the plate appeared related to the polar components of surface free energies of the particle and plate. The results of particle deposition in the model system were in good agreement with those in systems using water from a pond.