Experimental results on plasma treatments of polysulfone and polyetherimide to improve the wettability of these polymers are presented. The plasma is characterized by optical emission spectroscopy. The wettability of the polymer surfaces were checked by contact angle measurements and ESCA is used to compare the surfaces before and after plasma treatment. Correlations between contact angle, concentration of oxygen at the surface, and optical emission intensity of the OH radical have been established. Optimization of operational plasma parameters leading to the best wettability of the treated samples is reported.

In the Flexographic printing of polyethylene films with waterbased flexo inks, the partitioning of the surfactants between film/ink, pigment/ water, ink/air interfaces plays a major role in determining the printability. In addition, in formulations containing nonionic surfactants the equilibrium surface properties are much different from the diffusion limited dynamic properties. Problems associated with the printability are examined from an analysis of the above surface chemical considerations.

The present invention is a method of producing a photographic support. The method includes providing a photographic paper and transporting the photographic paper through an atmospheric glow discharge zone, wherein the atmospheric glow discharge zone contains a gas with a dielectric strength which is less than air. The atmospheric glow discharge zone is subjected to an electric frequency between 40 kHz and 13.56 Mhz and an electric field such that an atmospheric glow discharge is formed; and the photographic paper is coated with a polymeric coating.

Polyolefin coatings and films having release characteristics, also known as release sheets, are disclosed. The release sheets are formed by treating a sheet formed from polyolefin and dimethyl polysiloxane having functional end groups with a corona discharge. In a preferred embodiment, the release sheet is formed from polyolefin, the dimethyl polysiloxane, vinyl silane, an agent to graft the vinyl silane onto the polyolefin and a moisture curing agent by extrusion in the form of sheet, treating the sheet with a corona discharge and then subjecting the sheet to moisture. The release sheets may be used, for instance, as the backing sheet for labels.

We developed a new plasma treating method, incorporating the use of microwaves generated by an electronic cooking range. Using this method, polytetrafluorethylene (PTFE) and a copolymer of tetrafluoroethylene and hexafluoropropylene (FEP) were treated. Dialkylphthalates (DAP) were used as the standard liquids of contact angle measurements for evaluation of the wetting properties of plasma treated polymers. The components of surface tension (γ_L) due to the dispersion force (γ^d _L) and the polar force (γ^P _L) of DAP were calculated by Fowkes' equation from the contact angles (θ) on polypropylene. After plasma treatment cos θ of several standard liquids on PTFE and FEP increased. The linear relationship between γ_L(1 + cos θ)/(γ^d _L)^½ and (γ^P _L/γ^P _L)^½ was verified. γ_s and γ^d _s and γ^d _s of the plasma treated PTFE and FEP also increased. From the results of ESCA analysis, it was found that a significant amount of oxygen was introduced to the polymer surface by the plasma treatment. Peel strengths of a pressure sensitive adhesive bonded to PTFE and FEP increased approximately two-to threefold if the plasma treatment was used prior to bonding.

A metallized polymeric film comprises a sulphonated copolyester intermediate adherent layer having an alkali metal content of not more than 0.005 gram atoms percent.

A surface treatment method for improving the adhesiveness of a surface of a molded article made of a polyolefin resin with a printing ink, which entails irradiating the surface with an abundance of high-energy ultraviolet radiation from a high-output low-pressure mercury vapor lamp having an envelope made of synthetic quartz glass, and wherein the lamp has a wattage per unit lamp length of about 0.1-0.5 W/mm.

A method to modify the surface or fluoropolymer by a reactive gas plasma so that the surfaces have improved fluoropolymer to other substrate adhesive bond strength.

Wetting force at three-phase line was measured by the Wilhelmy technique using fibrous solids/liquid/liquid systems. Advancing and receding contact angles were calculated from the wetting forces during fiber immersion and emersion. The obtained results showed that contact angle hysteresis was due to the heterogeneity of the fiber surfaces. The dispersive and polar components of surface free energies of the fibers were determined from the advancing and receding contact angles, respectively. The Hamaker constants of the fibers were estimated from the dispersive components of their surface free energies.

For surface pre-treatment of a plastic article, such as a film sheet or the interior of a plastic molded article, by means of electrical corona-discharge, a device is provided having a generator 5 and a corona discharge device 11. The generator applied a high-frequency, high-voltage alternating current to the discharge electrodes 4 of the corona-discharge device 11. The grounded counterelectrode used is the metal core 2 of a roller 10 over whose peripheral coating 3 a film sheet 1 is transported. A housing 6 encompasses the electrodes 4 of the corona-discharge device 11 and is connected via a line 7 to an atomizer 8 in which a liquid is atomized to form an aerosol by means of a piezoelectrically operating ultrasonic vibration system or by two-component atomizer nozzles which operate at ultrasonic speed. A fan 9, the throughput rate of which can be regulated, is connected to the atomizer 8 and pushes the carrier gas, for example, air, for the aerosol through the atomizer into the corona-discharge device 11. Further corona-discharge devices can be present into which an aerosol of another liquid or only a reactive gas are fed.

Films of poly(methyl methacrylate) (PMMA) of both medium and high molecular weight have been prepared by casting onto clean glass. The difference in water contact angle of the surface originally in contact with glass. and air and the variation over time of this parameter have been studied. By use of the surface analytical techniques X-ray photoelectron spectroscopy (XPS) and, particularly, static secondary ion mass. spectroscopy (SSIMS), it has been shown that migration of low molecular weight impurities from the bulk of the film to the film/air interface is responsible for the contact angle behavior.

By measuring contact angles with water, glycerol and formamide on a number of polar surfaces, an estimate could be made of the electron-acceptor (γ⁺ ) and the electron-donor (γ⁻ ) parameters of glycerol (G) and formamide (F), relative to the parameters of. water (W), for which a reference value of γ⁺ _W = γ⁻ _W = 25.5 mJ/m² has been assumed. The values thus found are: γ⁺ _G ≈ 3.92 mJ/m² (which yields γ⁻ _G ≈ 57.4 mJ/m²) and γ⁺ _F ≈2.28 mJ/m² (which yields γ⁻ _F ≈ 39.6 mJ/m²).

With increasingly stringent EPA guidelines for controlling emissions of volatile organic compounds on the horizon, the desirability to move to water-based printing inks is evident This paper examines the effects of corona discharge treat ments which are commonly used to improve ink adhesion to polvethylene. Electron spectroscopy for chemical analysis (ESCA) was used to determine the surface chemi cal changes induced by corona treatments in pure polyethylene extruded films and in formulated resin systems This data was correlated with surface tension and ink adhesion measurements to show the effects of treatment and additives on the final printability of the films with particular emphasis on water-based inks. In addition, the effects of stonng treated film prior to printing and of retreating these films were also examined The results of these tests have shown that formulated linear low den sity polyethylene (LLDPE) films treat and print at least as easily as high-pressure low-density polyethylene (HP-LDPE) counterparts.

The reaction rates and products of remote oxygen plasma treatment, corona discharge, and ozone treatment of high and low density polyethylenes have been examined using x-ray photoelectron spectroscopy. The oxygen uptake by remote plasma treatment was faster than that of other surface treatments using excited oxygen species. A steady state concentration of 18 ± 1% oxygen can be attained within 1 s of exposure in the remote plasma.

With increasingly stringent EPA guidelines for controlling emissions of volatile organic compounds on the horizon, the desirability to move to water-based printing inks is evident This paper examines the effects of corona discharge treatments which are commonly used to improve ink adhesion to polvethylene. Electron spectroscopy for chemical analysis (ESCA) was used to determine the surface chemical changes induced by corona treatments in pure polyethylene extruded films and in formulated resin systems This data was correlated with surface tension and ink adhesion measurements to show the effects of treatment and additives on the final printability of the films with particular emphasis on water-based inks. In addition, the effects of stonng treated film prior to printing and of retreating these films were also examined The results of these tests have shown that formulated linear low density polyethylene (LLDPE) films treat and print at least as easily as high-pressure low-density polyethylene (HP-LDPE) counterparts.

A triode glow discharge system was used for the plasma treatment of polytetrafluoroethylene (PTFE) films and the formation of plasma polymerized hexamethyldisiloxane (PPHMDS) films on PTFE films. The nitrogen plasma increased the surface tension of the PTFE films to about 40 dyn/cm by applying an rf voltage to the substrate electrode. The contact angle of water on the PPHMDS films with the rf voltage was changed to 40°∼90° by corona discharge exposure for 30 s at 6 kV. This reduction is due to the decarbonization and the oxidation of PPHMDS films.

Many approaches have been used to infer the surface tension of solids from liquid contact angles. In most cases the different methods have not been verified by independent means because of the inherent difficulty in directly measuring a solid surface tension. This paper examines a range of diverse experiments which, together with appropriate thermodynamic models, permit such an independent verification to be made.

As part of an ongoing study, the focus has been on two methods of interpreting contact angles which often yield conflicting results; namely, the equation of state approach and the theory of surface tension components. The previous work has led to the conclusion that the latter approach is incorrect. In this paper the accuracy of these two methods is examined in a strictly empirical way through the interpretation of a wide body of experimental results. It is seen that the predictions of the equation of state approach are in much closer agreement with the various experiments than are those derived from the Fowkes equation.

The effect of gamma-radiation on the surface chemical properties of polystyrene was studied by ESCA and FT-IR. Gamma-radiation produces surface >CO and CO containing functional groups only, and also causes oxidation to depths >10 nm as detected by ESCA. FT-IR spectra showed that below the top few molecular layers ester, acid, and carbonyl groups of various types were present. The α,β-unsaturated carbonyl/acid groups form a higher proportion of the total carbonyls with increasing depth. Surface oxidation follows pseudo-first-order kinetics; the extent of interior oxidation is linear with dose.

Adhesion of polyimides to ceramic substrates such as SiO₂, Al₂O_3' and MgO, and interfacial interactions were studied using XPS, SEM, and the peel test. The peel strength of polyimides on SiO₂ and Al₂O₃ is almost identical and higher than that on MgO at the same polyimide thickness. Contrary to the failure within the polyimides on SiO₂ and Al₂O_3' Mg was found on the peeled PMDA-ODA acid-derived polyimide surface, implying weakening of MgO by interfacial reactions with polyamic acid. With the neutral polyamic ethyl ester, the locus of failure on MgO was changed to the apparent weak boundary layer of the ester-derived polyimide. On SiO₂ and Al₂O₃ the peel crack propagated with a discontinuous stick-slip process. The constant interspacing between transverse stick-slip striations on the peeled polyimide surfaces has confirmed that plastic bending is the major energy dissipation process with a minimal contribution from tensile loading.

Polyolefin films were surface-modified by different methods to improve the wetting and adhesion of water-borne printing inks. Polyethylene (PE) films were treated with corona at various energy levels. Surface-modified PE films were characterized by contact angle measurements and electron spectroscopy for chemical analysis (ESCA). Good wetting was already achieved with treatment at a lower energy level. Various degrees of adhesion were obtained at various degrees of treatment. A hydrophilic monomer, 2-hydroxyethylmethacrylate (HEMA), was polymerized onto the surfaces of polypropylene (PP) with radiation-induced grafting, which was carried out at two different radiation doses. In both cases, a thick, visible layer of polyHEMA was formed on the surface of PP, and satisfactory wetting was already achieved at lower radiation doses. Scanning electron microscopy (SEM) showed that different degrees of roughness were achieved at various radiation doses. Like the case of corona-treated PE, different degrees of adhesion were obtained at different degrees of surface treatment. This study shows that improved wetting alone is not satisfactory for good practical adhesion', regardless of the surface modification method used.