Transparent gas barriers are receiving considerable attention in the plastics industry for roll coating applications. The three principle vacuum deposition processes, evaporation, sputtering and plasma processing are the focus of transparent gas barrier work at various converters, resin producers and equipment manufacturers. Evaporation produces coatings at very high rates, but plasma processing has reported the best gas barrier results to date [ < 0.06 cc/100 in 2 /day for single-sided coatings on 0.5 mil polyethylene terephthalate (PET)]. Sputtering rates are lower than evaporation rates, but can produce a wide range of transparent oxides including the material of interest, silica. Evaporated, sputtered and plasma deposited coatings were produced and compared in terms of oxygen gas transmission and film stoichiometry. The plasma deposted coatings provided the best gas barriers and initial results show that the plasma processed barrier coatings are commercially feasible.
Large-scale application of plasma enhanced chemical vapor deposition (PECVD) and PECVDlike proce §ses have been limited due to the inherent complexity and dependence of the reactor geometry and gas flow patterns on the process variables. Plasma diagnostics and robust experimental design have enabled large-area application of an organosilicon-based chemical plasma deposition process for application on rigid polymeric substrates (bottles, trays, etc.) and thinner (0.5 mil thick) polymeric films. The process was successfully transferred among four vacuum systems, each employing different electrodes, gas flow geometries, and pumping configurations. Purthermore, desirable film properties were obtained at deposition rates in excess of 200 A/s in the pilot scale roll-to-rol1 coater. In the pilot bottle coater, large loads of bottles (117, 32 oz containers) were uniformly coated on a routine basis. A historical account of the process development and technical hurdles, along with experimental data from the four reactors studied, will be presented. 1615 J.
SiO x thin films continue to be developed for polymeric flexible substrates. During the past year significant progress has been made on plasma deposition onto PET, LDPE, BOPP and BON polymer films. In addition, the first two 1.5 meter wide plasma roll coaters were completed and installed. The current state of the roll-to-roll coating developments on BOPP, LDPE, PET and BON will be reported for the 0.3 meter wide roll coater, R9, the 0.66 meter wide roll coater, Flex-1, along with data from the 1.5 meter wide coater, Flex-3, operations. The article focuses on a new stretch tester that measures oxygen transmission of stretched SiO x coated polymers. Data from the plasma coatings along with comparative measurements made on commercially available evaporated products clearly shows a strong inverse relationship between the SiO x coating thickness and the onset of failure (strain) S f . Plasma coatings were stretched to 11.9% before failure occurred while the evaporated materials degraded at S f = 2-3%. The stretch tester is a repeatable technique to assess the convertibility of the SiO x coated polymers and to make quantitative assessments between competitive materials. A model is also presented outlining the key parameters in achieving gas barrier properties with thin SiO x and AlO x coatings.
Measurements using the derived calculation scheme to determine the electron temperature from optical emission spectroscopy are presented. The electron temperature was measured using both optical emission spectroscopy and Langmuir probes with our computer based system. The computer allowed us to make both measurements and do the calculations on line in a reasonable amount of time. Because of the accuracy of our emission spectrometer, we made several Langmuir probe measurements for each emission spectrum taken. We first determined that the optically measured electron temperature and Langmuir probe measured electron temperature were following the same trend with variations in the process variables. In addition to varying process variables, we also determined the effect of adding an additional gas to the discharge. The results presented verify that our optically determined electron temperature is valid in this case.
Lubricious thin films are used in plastic medical syringes in order to reduce the frictional forces between the syringe barrel and the rubber plunger. Polydimethylsiloxane (PDMS) liquid films are the current accepted technology for reducing the friction forces in plastic medical syringes. However, major issues with these PDMS films exist, including interactions of the film with the stored injectable drugs and variations in the frictional response as the syringes are aged over time. A new silicon based, lubricious octamethylcyclotetrasiloxane (L-OMCTS) thin film solid lubricant has been developed as a replacement for PDMS that provides acceptable and stable frictional responses without interacting with injectable drugs. A novel test method has been developed that can be used to successfully characterise the sliding frictional response of the L-OMCTS thin films at the syringe barrel and plunger interface. This test method will be used to provide future insight into how the frictional response of the L-OMCTS thin films is affected by various system parameters. This paper will mainly discuss the design of this new test method and provide some preliminary frictional response data.
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