Transparent Barrier Coatings Research Articles

Structural and optical properties o plasma-deposited a-C:H:Si:O:N films

Thin a-C:H:Si:O:N films were deposited from plasmas fed hexamethyldisiloxane, oxygen and nitrogen, and characterized as a function of the partial pressure of oxygen in the feed, Rox. Deposition rates varied from 10 to 27 nm min-1. Surface roughness was independent of Rox, being around 10 nm. The films contain C=C and C=O, and also Si-C and Si-O-Si groups. Lower [C] and [N] but greater [O] and [Si] were measured in the films as Rox was increased. Refractive indices of ~ 1.5 and optical energy gaps which fell from ~ 3.3 to ~2.3 eV were observed with increasing Rox. The Urbach energy fell with increasing optical gap, which is characteristic of amorphous materials. Such materials have potential as transparent barrier coatings.

Aluminum oxide barrier coatings on polymer films for food packaging applications

In the field of packaging, barrier layers are functional films, which can be applied to polymeric substrates with the objective of enhancing their end-use properties. For food packaging applications, the packaging material is required to preserve packaged food stuffs and protect them from a variety of environmental influences, particularly moisture and oxygen ingress and UV radiation. Aluminum metallized films are widely used for this purpose. More recently, transparent barrier coatings based on aluminum oxide or silicon oxide have been introduced in order to fulfill requirements such as product visibility, microwaveability or retortability. With the demand for transparent barrier films for low-cost packaging applications growing, the use of high-speed vacuum deposition techniques, such as roll-to-roll metallizers, has become a favorable and powerful tool. In this study, aluminum oxide barrier coatings have been deposited onto biaxially oriented polypropylene and polyethylene terephthalate film substrates via reactive evaporation using an industrial ‘boat-type’ roll-to-roll metallizer. The coated films have been investigated and compared to uncoated films in terms of barrier properties, surface topography, roughness and surface energy using scanning electron microscopy, atomic force microscopy and contact angle measurement. Coating to substrate adhesion and coating thickness have been examined via peel tests and transmission electron microscopy, respectively.

Transparent Barrier Coatings on High Temperature Resisting Polymer Substrates for Flexible Electronic Applications

Silicon nitride and parylene thin films were deposited onto flexible polyimide (PI) substrates using plasma-enhanced chemical vapor deposition and a parylene reactor for transparent barrier applications. The PI substrates from the Industry Technology Research Institute with high optical transmittance and high glass transition temperature were used. A relatively high growth temperature of was chosen to deposit the films. To characterize the films deposited under different growth temperatures, a wet-etching process was performed to visualize the defect distribution in the barrier films. After 120 min of etching, the etching area ratio decreased from 44.9 to 6.7%, while the average defect spacing increased from 125 to with increasing growth temperature. Under room temperature and relative humidity of 50%, four stacks with the films deposited at 80 and were demonstrated to decrease the water vapor transmission rate to and , respectively. As a result, ultralow permeation can be achieved with less repeating barrier stacks by using high temperature deposited films in the barrier structures.

Conversion of Perhydropolysilazane into a SiOx Network Triggered by Vacuum Ultraviolet Irradiation: Access to Flexible, Transparent Barrier Coatings

The photochemical conversion of 200-500 nm layers of perhydropolysilazane --(SiH2-NH)n-- (PHPS) in the presence of oxygen into an SiOx network was studied. Different UV sources in the wavelength range of 160-240 nm, that is, 172 nm Xe2* and 222 nm KrCl* excimer, and 185 nm Hg low-pressure (HgLP) lamps were used for these purposes. The role of both ozone and O(1D) as well as of catalytic amounts of tertiary amines in the degradation process of PHPS and the formation of SiOx were studied. In this context, the kinetics of the entire reaction were elucidated and allowed both a continuous and discontinuous process to be established for the production of fully transparent, flexible barrier coatings. Barrier improvement factors (BIFs) of 400 were achieved with one single layer on 23 microm poly(ethyleneterephthalate) (PET), which translated into oxygen transmission rates (OTRs) of 0.20 cm3 m(-2) day(-1) bar(-1). Double layers prepared by this technique allowed the realization of OTRs of <or=0.1 cm3 m(-2) day(-1) bar(-1), corresponding to BIFs of >or=800.

Relationship between the microstructure and the water permeability of transparent gas barrier coatings

The relationship between the microstructure and the water vapor permeability of transparent barrier coatings on polymeric films has been studied by atomic force microscopy (AFM). The average grain size, d, and the surface pore fractal dimension, D s, of the different coatings were determined from the AFM images. It was observed that those films with low d and high D s values presented a low water vapor permeability whereas when either d was high or D s was low the water vapor permeability increased. These differences are explained on the basis of the different dependences of the two main water molecule transport mechanisms (Knudsen and the surface diffusion) on the coating microstructure.

Study of Defect Numbers and Distributions in Pecvd S102 Transparent Barrier Coatings on Pet

AbstractTransparent ceramic barrier films are the object of increasing interest in packaging, pharmaceutical, optical, and electronics industries, since they can reduce the permeation rate of oxygen (OTR) and/or water vapor (WVTR) by several orders of magnitude. We prepare silicon dioxide (Si02) or nitride (“SiN”) barrier layers by plasma-enhanced chemical vapor deposition (PECVD). We have shown that OTR (and WVTR) decrease with increasing coating thickness, d, to a certain asymptotic minimum value, when d ≥ 50 nm; the residual permeation is attributed to the presence of microscopic defects in the coating. Since the coatings are transparent and very thin, the detection of defects and the analysis of their origin are very difficult.We have recently developed techniques based on reactive ion etching (RIE) in oxygen plasma to render visible micrometer- or sub-micrometer-sized defects in transparent barrier coatings on transparent polymers. These techniques can be used to better understand the origins of defects in these coatings on a microscopic scale, as well as for mapping and counting defect density on a macroscopic scale (tens of cm2 or more).In this article we present a correlation between measured 02 transmission rate (OTR) values and the number density and size distribution of defects in SiO2 barrier coatings. Excellent agreement between measured and calculated OTR values allows us to confirm that residual OTR is indeed controlled by pinhole defects; our results also compare well with published data for aluminized PET.

Overview on modern vacuum web coating technology

Vacuum coatings on web shaped materials are covering a wide range of applications from decorative coatings and barrier coatings for the packaging industry, capacitor film coating for the electronics industry and coatings for magnetic tape up to different functional coatings with specially tailored mechanical, chemical, optical, electrical or magnetic properties. Depending on the application, processes like evaporation from resistance heated boats, electron beam evaporation, magnetron sputtering and plasma enhanced chemical vapor deposition are used. Concepts and dimensions of different vacuum web coating systems are optimized for the applications and processes. In this paper a hardware description of different web coaters is given along with information about some typical processes. We show, that modern vacuum web coaters are the appropriate production tools for metallized web with two-dimensional patterns of nonmetallized areas for the production of capacitors, metallized web or paper for the packaging industry, transparent barrier coatings for packaging, multilayer window films with precisely defined optical properties and a lot of different other coated products.

Inorganic coatings on polymers

There has been a growing interest over the last few years in the development of industrial transparent barrier coatings. The vacuum-deposited materials are based on silicon (SiO χ ) and aluminium (Al y O z ) oxide compounds. Significant improvements are observed in the barrier properties of coated plastic films. In this paper we review the deposition techniques and focus on the influence of surface preparation before deposition. Plasma activation of the polymer surfaces increases the adhesion of the coating to the substrate. New results obtained by atomic force microscopy and transmission electron microscopy complement our published X-ray photoelectron spectroscopy data and confirm the importance of the formation of chemical bonds at the coating-polymer interface.

Inorganic coatings on polymers

There has been a growing interest over the last few years in the development of industrial transparent barrier coatings. The vacuum-deposited materials are based on silicon (SiOχ) and aluminium (AlyOz) oxide compounds. Significant improvements are observed in the barrier properties of coated plastic films. In this paper we review the deposition techniques and focus on the influence of surface preparation before deposition. Plasma activation of the polymer surfaces increases the adhesion of the coating to the substrate. New results obtained by atomic force microscopy and transmission electron microscopy complement our published X-ray photoelectron spectroscopy data and confirm the importance of the formation of chemical bonds at the coating-polymer interface.

ＰＶＤおよびＣＶＤの新しい展開 透明バリヤー膜の形成技術

ＰＶＤおよびＣＶＤの新しい展開 透明バリヤー膜の形成技術