The present invention is a process for treating plastic substrates to improve their surface properties. The process involves exposing the plastic substrate to UV radiation at wavelengths of 185 and 254 nm in the presence of atomic oxygen for about 5 to 60 minutes. The treated plastic substrates have improved wettability. The process is particularly well suited for the treatment of plastic intraocular lenses and plastic packaging materials such as PVC film.

According to this invention, there is provided an atmospheric pressure plasma surface treatment process comprising the steps of introducing a gas in a plasma reaction apparatus having a pair of dielectric-covered electrodes having opposing surfaces on at least one of which is provided with a solid dielectric; performing plasma excitation under atmospheric pressure; and surface treating an object placed between the opposing electrodes, wherein the gas introduced is a gaseous composition consisting essentially of argon, helium and/or ketone. This process makes it possible to quickly imparting hydrophilic nature to surfaces of an object made of a plastic to be treated. The hydrophilic nature given lasts long.

The bonding properties of polyolefin films in composites are improved by a treatment with a low pressure plasma.

An apparatus and method are provided for surface treating the inside surfaces of hollow or three dimensional plastic objects. While the invention will be described with respect to plastic objects, it will be understood that other objects having a high dielectric strength, such as ceramics, cardboard, paper and wood, may be similarly treated. The surface treating is effected by selectively directing a high voltage plasma field to a selected interior surface of the object to enhance adhesion of various glues, inks and the like. The plasma field is generated in the interior of a tunnel directed into an opening of the hollow portion of the object to be treated. A specially designed electrode is supported from the opening to direct in a controlled manner the field to the selected interior area of the object to be treated. The electrode is supported from a high dielectric shield covering a central area of the opening to direct the plasma field around the shield to a laterally extending electrode below the shield. The electrode is supported from the shield by a conductive rod and is fashioned to extend in a spaced relation to the interior of the object to provide a proper energy level in the plasma to the area to be treated. A plurality of electrodes may be utilized to treat separate and selected interior areas of the object.

A polymeric sheet structure consists of an adhesion-promoting coating on at least one surface of the substrate. The adhesion-improving coating is produced by treating this substrate surface with an electrical corona discharge between high voltage electrodes and a grounded counter-electrode while simultaneously spraying an aerosol into the corona discharge zone. The aerosol contains, for example, an aqueous emulsion of thermoplastic and/or crosslinkable components as an adhesion-promoting agent.

Apparatus and method for treating the interior surfaces of hollow plastic objects to improve their adherency to and compatibility with another component, such as polyurethane foam. The invention consists of creating a vacuum in the object and drawing a conductive gas inside the object. A pair of electrodes are spaced apart from each other, and a source of electricity is provided thereto of sufficient intensity to produce an electrical discharge across the gap between the electrodes when an object is in the gap between the electrodes. The electrodes are arranged with regard to the size and configuration of the object to provide ionization of the conductive gas inside the object to surface treat the inner walls.

Disclosed herein is a method for surface treatment which comprises subjecting an object for surface treatment to an atmospheric pressure plasma while rolling or floating said object in an insulating vessel fed with a prescribed gas and provided on the outside thereof or on both the outside and inside thereof with electrodes for voltage application and grounding, said atmospheric pressure plasma occurring upon application of a voltage to said electrodes. This method permits simple, certain, and uniform surface treatment of any objects in the form of lump or sphere. The surface treatment by the atmospheric pressure plasma does not need the apparatus to be evacuated. Therefore, it can be carried out in a simple apparatus without causing the object for surface treatment to release volatile matters.

Disclosed also herein is a method for the surface treatment of vulcanized rubber with an atmospheric pressure plasma in the presence of an oxygen-containing gas and halogen containing gases. This method is simple and permits the surface treatment of vulcanized rubber in a clean environment. The surface treatment by this method provides the vulcanized rubber with a surface having better adhesion properties than the surface treatment with a low-pressure glow plasma. Moreover, the surface treatment is limited only to a very thin surface layer, with the vulcanized rubber itself remaining intact.

Polymer materials such as film and fabrics, woven, non-woven and meltblown, may be non-destructively surface treated to improve water wettability, wickability, and other characteristics by exposure to a glow discharge plasma sustained at substantially atmospheric pressure in air or modified gas atmospheres comprising helium or argon.

A meat product package including an enclosing film having an EVA-containing inside surface and an in situ aqueous medium-cooked meat product in adhering relation to the film inside surface as the meat contacting and adhering surface. Starch particles are preferably dispersed across the meat contacting surface which has been both irradiated and subjected to corona treatment. A method for corona treating a thermoplastic tube inside surface in which small particles within the flat tube separate opposite surfaces providing voids, and the electric discharge crosses the flat tube through the voids.

A steady-state, glow discharge plasma is generated at one atmosphere of pressure within the volume between a pair of insulated metal plate electrodes spaced up to 5 cm apart and R.F. energized with an rms potential of 1 to 5 KV at 1 to 100 KHz. Space between the electrodes is occupied by air, nitrous oxide, a noble gas such as helium, neon, argon, etc. or mixtures thereof. The electrodes are charged by an impedance matching network adjusted to produce the most stable, uniform glow discharge.

Tightly integrated composite products are obtained by treating a fluoropolymer member on its surface with atmospheric pressure glow discharge plasma in a helium gas atmosphere containing 97% by volume or more of helium gas, and joining another member of rubber compositions, resins, metals, ceramics, or semiconductors to the surface treated fluoropolymer member. By using a fluoropolymer sheet as the fluoropolymer member and a metal or synthetic resin layer as the other member, there are obtained weather-resistant composite sheets in which the layer is firmly bonded to the fluoropolymer sheet.

Polymer materials such as film and fabrics, woven, non-woven and meltblown, may be non-destructively surface treated to improve water wettability by exposure to a glow discharge plasma sustained at substantially atmospheric pressure in a modified gas atmosphere comprising helium or argon.

A surface treating method is described, which method comprising applying, between electrodes, a potential sufficient to cause corona discharge to occur in the presence of a gas which comprises molecules containing at least one atom selected from the group consisting of halogen atom, oxygen atom and nitrogen atom. The resultant corona discharge is applied to an object to be treated for the surface treatment of the object, said object being outside said electrodes. The excellent adhesive surface can be obtained when said object is separated from said electrodes at a distance in the range of 10 mm to 5 m.

The present invention is a polyester film base which has a surface approximately 5 nm thick. The surface of the film base has been altered to include about 6 to 15 atomic percent nitrogen in the form of imines, secondary amines and primary amines in the ratio of about 1:1:2. The invention also includes a film base whose surface includes oxygen in the form of hydroxyl, ether, epoxy, carbonyl or carboxyl groups wherein the oxygen is about 4 to 10 atomic percent above the original surface content of the base. The polyester film base can be either polyethylene terephthalate or polyethylene naphthalate.

The present invention is a polyester film base which has a surface approximately 5 nm thick. The surface of the film base has been altered to include about 6 to 15 atomic percent nitrogen in the form of imines, secondary amines and primary amines in the ratio of about 1:1:2. The invention also includes a film base whose surface includes oxygen in the form of hydroxyl, ether, epoxy, carbonyl or carboxyl groups wherein the oxygen is about 4 to 10 atomic percent above the original surface content of the base. The polyester film base can be either polyethylene terephthalate or polyethylene naphthalate.

A web or film is electrostatically charged by sequentially subjecting the web or film to a series of electric fields such that adjacent electric fields have substantially opposite polarities. Both a method and apparatus are disclosed for charging the web or film.

A method of preventing localized arcing to ground during treatment of a sheet material in a corona discharge field generated by a corona discharge apparatus having at least two electrodes, which method involves passing the sheet material to be treated through the corona discharge field, in which the sheet material to be treated is electrically isolated from the electrodes. When the corona discharge apparatus has a bare metal electrode and a dielectric-covered electrode, the sheet material to be treated is passed through the corona discharge field as a layer of a multilayered composite having at least three layers, in which at least one of the layers is a nonconductive sheet material situated between the sheet material to be treated and the bare metal electrode. The method may be employed to treat a hydrophobic sheet material having a porosity, in which case the hydrophobic sheet material is passed through a corona discharge field generated by a corona discharge apparatus having a bare metal electrode and a dielectric covered electrode under conditions adapted to render the porous sheet wettable. The hydrophobic sheet material is a layer of a multilayered composite having at least three layers, in which at least one layer is a nonconductive sheet material situated between the sheet material to be treated and the bare metal electrode and one of the at least three layers is a nonconductive, nonporous sheet material.

In the manufacture of composite paperboard/polymer packages, the adhesion between the polymer component and paperboard component can be enhanced by treating the polymer film with a surface treatment, for example, ozone, before the two components are brought together. The present invention is particularly applicable to a blow molding process employing one or more paperboard blanks and a blow molded polymer film.

Surface treated articles of polyethylene terephthalate (PET) are disclosed having low self-adhesion and high bondability to other surfaces. The articles comprise oriented PET and about 100-5000 ppm of a particulate additive uniformly dispersed therein. The additive is chemically inert to PET and has an average particle size of about 0.03 to 0.6 micrometers. A process for the preparation of such articles is also disclosed.

The present invention provides a method of modifying the surface of a polymeric substrate, e.g., to improve the wettability of the polymer film surface and/or alter the reactivity of the surface of the substrate by further oxidation or affixation of nitrogen, comprising exposing the substrate to a flame. The flame is supported by a fuel and oxidizer mixture that includes an effective amount, for modifying the polymeric substrate, of at least one compound that functions as a fuel or oxidizer substitute and is selected from an oxygen-containing compound, in which the oxygen comprises between about 10 and 50 atomic percent of the compound, a nitrogen-containing compound or an oxygen-nitrogen-containing compound. In a preferred embodiment, which affixes nitrogen or nitrogen-containing chemical groups onto the surface of the film, the flame is supported by a fuel and oxidizer mixture that includes ammonia, nitrous oxide, nitric oxide or a mixture thereof in an effective amount. Large increases in the ASTM wetting test, e.g., greater than 13 mJ/m² over that reported with conventional flame-treating processes, have been observed in films treated according to this invention. In addition, significant increases in polymer film surface oxidation levels, e.g., as much as 55 percent, have been observed, as have significant amounts of nitrogen and nitrogen-containing chemical groups affixed to film surfaces.

The present invention is a method and apparatus for treating a polyester support such as polyethylene napthalate or polyethylene terephthalate. The treatment is carried out at near atmospheric pressure in a gas of helium and nitrogen or oxygen. The treatment uses anodized aluminum electrodes and an atmospheric glow discharge results when the electrodes are connected to an RF generator and spaced about 2 mm apart. The process and apparatus improve adhesion of subsequently coated emulsions on the polyester support.

Method of improving wetting and adhesive properties of dielectric materials by injecting electrical charges into the substrate under conditions such that the primary effect on the surface is that of charging so that improved wettability of the surface will be achieved. Flowable materials are then applied to the surface and cured in situ to permanently adhere the flowable materials to the surface.

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.

The present invention provides a method of modifying the surface of a polymeric substrate, e.g., to improve the wettability of the polymer film surface and/or alter the reactivity of the surface of the substrate by further oxidation, comprising exposing the substrate to a flame. The flame is supported by a fuel and oxidizer mixture that includes an effective amount, for modifying the polymeric substrate, of at least one oxygen-containing compound that functions as a fuel substitute. Oxygen comprises between about 10 and 50 atomic percent of the compound. Large increases in the ASTM wetting test over that reported with conventional flame-treating processes, have been observed in films treated according to this invention. In addition, significant increases in polymer film surface oxidation levels have been observed.

Apparatus capable of sustained glow discharge at atmospheric pressure mounted along the web path in a web coating machine ahead of the point of coating application, for glow discharge treatment of the surface of a polymeric web shortly before coating. Latencies of treatment (the time between treatment and coating) approaching zero are possible, minimizing or preventing loss of treatment effect and maximizing adherence of a coated layer to the web surface. Elimination of one or more conventional subbing adhesion layers on the web surface is possible in some applications.

A process for corona treating a polymer is described. The process involves exposing at least one surface of an article comprising a polymeric material selected from the group consisting of fluoropolymers, polycarbonates, and polyimides to a corona discharge in an atmosphere containing nitrogen and about 0.01 to about 10 percent of an additional gas selected from the group consisting of hydrogen, ammonia and mixtures thereof.

A multi layer film having enhanced barrier properties against transmission of oxygen and water vapor is provided. The multi layer film includes a polypropylene base layer, with a high density polyethylene layer on at least one surface of the polypropylene base layer. The polyethylene layer includes a surface which has been subjected to plasma treatment with a hydroxyl-donating material such as a methanol. The film further includes a metal layer deposited on the plasma treated surface, such as a layer of vacuum deposited aluminum. Multi layer films according to the present invention are particularly useful as packaging films for food products.

A corona discharge treatment apparatus or system and method for treating both insulating and conductive surfaces including a ground member and a plurality of flat electrodes aligned flat side in a row and each electrode having at least one finger-like protrusion with a pointed tip having a radius in the range of about 0.010 to about 0.125 and operating in a high kilo frequency range of about 20k Hz to 30k Hz. The electrodes are individually rotatably mounted to move to and away from the ground member so that the row length of the electrodes can be adjusted to be the same dimension as the width of material to be treated or to only treat selected portions of the material.

Apparatus and process for plasma treatment of moving webs, or films, are disclosed. The apparatus includes magnets and multiple hollow cathodes, which, in the presence of a plasma, magnetically focuses and thereby intensifies the plasma to one side of the film surface. The moving web is positioned either between the hollow cathodes and the magnets or in front of the hollow cathodes and the magnets. The plasma treatment functionalizes the film surface.

A plasma treater incorporates a porous metallic layer in one of the electrodes. The porous layer is selected with pores of average size within one order of magnitude of the mean free path of the plasma gas at atmospheric pressure. The plasma gas is injected into the electrode at substantially atmospheric pressure and allowed to diffuse through the porous layer, thereby forming a uniform glow-discharge plasma. The film material to be treated is exposed to the plasma created between this electrode and a second electrode covered by a dielectric layer. Because of the micron size of the pores of the porous metal, each pore also produces a hollow cathode effect that facilitates the ionization of the plasma gas. As a result, a steady-state glow-discharge plasma is produced at atmospheric pressure and at power frequencies as low as 60 Hz.

A method and apparatus for producing a polyethylene coated paperboard material with a mirror-pocket finish and a predetermined Dyne level is disclosed herein. The apparatus and method utilizes a double corona treatment on a single polyethylene surface to create the material with the predetermined Dyne level. Such paperboard material is often used for fabrication of cups, and the like. The predetermined Dyne level is required for printing requirements. The method and apparatus allow for the production of the predetermined Dyne level material at standard laminator operating speeds.

Large area atmospheric-pressure plasma jet. A plasma discharge that can be operated at atmospheric pressure and near room temperature using 13.56 MHz rf power is described. Unlike plasma torches, the discharge produces a gas-phase effluent no hotter than 250° C. at an applied power of about 300 W, and shows distinct non-thermal characteristics. In the simplest design, two planar, parallel electrodes are employed to generate a plasma in the volume therebetween. A “jet” of long-lived metastable and reactive species that are capable of rapidly cleaning or etching metals and other materials is generated which extends up to 8 in. beyond the open end of the electrodes. Films and coatings may also be removed by these species. Arcing is prevented in the apparatus by using gas mixtures containing He, which limits ionization, by using high flow velocities, and by properly spacing the rf-powered electrode. Because of the atmospheric pressure operation, there is a negligible density of ions surviving for a sufficiently long distance beyond the active plasma discharge to bombard a workpiece, unlike the situation for low-pressure plasma sources and conventional plasma processing methods.

The present invention relates to a corona station for the preliminary processing of a strip material. The corona station includes at least one electrode (18) connected to a high-voltage power supply through connection means, a housing containing at least partially the electrode (18) and the connection means, and at least one cylindrical counter-electrode (17), wherein the strip of material (16) does not rest on the whole surface of said counter-electrode (17).

A method and apparatus are taught for treating polyolefin containing or polyolefin-coated webs or laminates for obtaining the proper surface characteristics to promote adhesion of photosensitive coating materials and/or layers typically coated thereon. The web is passed through a high-voltage sheath region or dark space of the plasma generated by a powered electrode residing in a discharge zone. The frequency of the driving voltage must be above a lower bound dictated by the properties of the paper support and the plasma, and it must be below an upper bound beyond which the sheath voltages drop significantly and it is observed that the benefits of this approach diminish. The dark space is generated by a treatment electrode in a treatment zone. There is a counter electrode having a surface area in said treatment zone which is at least as great as the surface area of the treatment electrode. A power supply is included for driving the treatment electrode with an oscillating high voltage at a frequency less than about 2 MHz and greater than 1/tc where tc is the charging time of a web surface exposed to a rms ion current in the plasma.

A treater system includes a conductive roller electrode that supports a moving web that is to be treated. One or more active electrode assemblies mounted to support headers have a pair of active electrodes that are positioned to treat one surface of the web as the web passes over the roller electrode. Air or a gas/gas mixture can be selectively piped to a chamber adjacent the active electrodes and diffused along the length of the discharge surfaces to allow the treater to operate in three distinct modes: corona, chemical corona and atmospheric plasma. The active electrodes are cooled by passing air into and through tubular bodies of the active electrodes.

A porous metallic layer is incorporated in one of the electrodes of a plasma treatment system. A plasma gas is injected into the electrode at substantially atmospheric pressure and allowed to diffuse through the porous layer, thereby forming a uniform glow-discharge plasma. The film material to be treated is exposed to the plasma created between this electrode and a second electrode covered by a dielectric layer. Because of the micron size of the pores of the porous metal, each pore also produces a hollow cathode effect that facilitates the ionization of the plasma gas. As a result, a steady-state glow-discharge plasma is produced at atmospheric pressure and at power frequencies as low as 60 Hz. According to another aspect of the invention, vapor deposition is carried out in combination with plasma treatment by vaporizing a substance of interest, mixing it with the plasma gas, and diffusing the mixture through the porous electrode. A heater is used to maintain the temperature of the electrode above the condensation temperature of the substance to prevent deposition during diffusion. Thus, plasma treatment and vapor deposition can be carried out on a target substrate at the same time at atmospheric pressure.

The water base adhesion promotor for polypropylene comprises: a grafted polypropylene chloride, which includes a polypropylene chloride moiety and a maleic anhydride moiety as bonded thereto, and which has a chlorine content of 15-25 weight % and a maleic anhydride moiety content of 1-5 weight %; an amine-neutralized water-soluble resin; a wettability-improving agent; and water; and is characterized by having: a combination ratio of 25-90 weight % as of the grafted polypropylene chloride to the total of the grafted polypropylene chloride and the amine-neutralized water-soluble resin; a combination ratio of 2.5-6.0 weight % as of the wettability-improving agent to the entirety of the promotor; and a solid content of 2-10 weight % of the entirety of the promotor. The method for coating to polypropylene materials comprises: a pretreatment step in which the polypropylene material is beforehand cleaned and then the above water base adhesion promotor is applied, and then dried; and a coating step in which a paint is coated to the material after the pretreatment step.

In accordance with the present invention, a directed plasma beam is employed in air to selectively remove coatings from paper products at high production rates. The shape and intensity of the beam is controlled to obtain a controlled rate of removal of the coating. The method does not require vacuum to be established and allows for the plasma to be generated from high pressure air.

Hydrophobic polymer materials having improved dyeability with water-based dyes are prepared by treating a hydrophobic polymer with aglow discharge plasma generated from working gases selected from SO₂, O₂, N₂, He, H₂, CO₂, CF₄, NO, N₂O, 2-Hydroxypropyl Methacrylate (HPMA), air or combinations thereof, in which a treated material comprises a hydrophobic inner core and a hydrophilic outer sheath having polar functional groups. A method of treating hydrophobic polymer materials using a glow discharge plasma, preferably at high pressure (e.g., about 50 Torr or greater), thereby modifying the active surface characteristics of the polymer to contain polar functional groups is also presented.

A method and apparatus are taught for treating paper webs for obtaining the proper surface characteristics to promote adhesion of nonphotosensitive coating materials and/or layers typically coated thereon. The web is passed through a high-voltage sheath region or dark space of the plasma generated by a powered electrode residing in a discharge zone. The frequency of the driving voltage must be above a lower bound dictated by the properties of the paper support and the plasma, and it must be below an upper bound beyond which the sheath voltages drop significantly and it is observed that the benefits of this approach diminish. The dark space is generated by a treatment electrode in a treatment zone. There is a counter electrode having a surface area in said treatment zone which is at least as great as the surface area of the treatment electrode. A power supply is included for driving the treatment electrode with an oscillating high voltage at a frequency less than about 2 MHz and greater than 1/t_c where t_c is the charging time of a web surface exposed to a rms ion current in the plasma.