his invention relates to a method by which substantial improvement can be obtained in the electric glow discharge treatment of polyolefin, such as polyethylene or polypropylene, structures to improve the anchorage characteristic of a surface thereof. More particularly, the invention is concerned with improving processes and apparatus for treating polyethylene or other thermoplastic film or article to render its surface adherent to printing inks or other coating materials, wherein the surface treatment is accomplished by means of an electric glow discharge, as for example, in accordance with the disclosure of the copending applications of Kaghan and Stoneback, Ser. No. 540,137, filed Oct. 12, 1955, and issued Nov. 11, 1958, as U.S. 2,859,481 and of Berthold and Pace, Ser. No. 359,352 filed June 3, 1953, and issued May 3, 1960, as U.S. 2,935,418. This application is a continuationin-part of our copending application Ser. No. 602,506 filed Aug. 7, 1956, now abandoned.

This invention relates to a process for preparing poly: vinylbutyral sheeting which has a decreased tendency to block. More specifically, this invention relates to treating polyvinylbutyral by electrical discharge in a nitrogen atmosphere and thereby obtaining a surface on the sheeting that has a decreased tendency to adhere to itself or to other similarly treated polyvinylbutyral sheets.

Apparatus for treating the exterior surfaces of plastic objects to improve their adherency to and compatibility with inks and adhesives comprising a pair of electrodes spaced apart from each other, means including a source of electric current of sufficient intensity to produce a spark discharge across the gap between said electrodes, electrical conducting means connecting said electrodes and said source, and means for positioning the objects in the gap between said electrodes, and electrodes being arranged with regard to the size and configuration of the objects to provide a nearly direct electron path around the objects whereby desired portions of the object surfaces may be passed over by the spark discharges during the passage of the latter along said path from electrode to electrode.

Metallized polyethylene terephthalate film produced by first subjecting a surface of the film to a reducing flame, and thereafter depositing on the treated surface a coating of metal, e.g., aluminum, deposited from a vapor of the metal.

This application is a continuation-in-part of our copeuding application Ser. No. 469,317, filed July 2, 1965 now abandoned.

This invention relates to a process for the improvement of the adhesion of vacuum-deposited metal to linear polyester film. More specifically, it relates to the flame treatment of polyethylene terephthalate film to promote the adhesion of vacuum-deposited metal.

This invention relates to a process for treating the surface of a stretched film of a polyester or polypropylene or copolymers or polymer mixtures of the latter containing at least 60 percent by weight, calculated on the total polymer weight, of propylene, in order to improve the adhesion of the film surface to a heatsealable coating, which comprises subjecting the film surface to a corona discharge in an atmosphere consisting essentially of nitrogen or carbon dioxide containing not more than about 15 percent by volume of oxygen, at a film temperature in the range of room temperature to about 25° to 50° C. below the softening point of the stretched film. The invention also relates to the films so treated.

An improved electrode for use in apparatus for the treatment of the surface of a thin sheet of material includes an electrically conductive cylindrical core, a thin layer of dielectric material covering the cylindrical surface of the core, and an outer layer or sheath of electrically conductive material insulated from the core and completely surrounding the dielectric material. The electrode cooperates with one or more stationary electrodes in corona treatment apparatus to reduce the possibility of electrode arcing and to establish an electric field in the electrode gap with greater efficiency than the prior art.

Polymeric films are exposed to a low energy electron beam in order to alter the permeability characteristics of the polymeric films for gases. The so treated polymeric films have enhanced utility for separating gases such as hydrogen and helium from mixtures containing same.

An electrode and method for electrostatically treating the surface of a substrate of continuous sheet metal material, wherein the electrode comprises a rotatable, electrically conductive cylindrical member onto and off of a segmental portion of the peripheral surface of which the substrate is continuously wrapped. The cylindrical member has its peripheral surface encompassed by a non-conductive material for engaging the substrate as it passes around the cylindrical member. The non-conductive material includes an insulating barrier for insulating the substrate from the cylindrical member, and outwardly opening cavities to provide an air space between the substrate and the cylindrical member, in the area of the substrate wrapped on the cylindrical member, to enable ionization of the air in such air space for treating the substrate surface wrapped on the cylindrical member upon application of a potential difference between the cylindrical member and the substrate.

The present invention relates to a method and apparatus for the production of plastic materials having improved surface bonding properties for bonding other materials to the plastic materials. The new method comprises passing the plastic material through an electrically charged flame. The apparatus used to perform the method may have several embodiments which include an electrical power supply circuit, a discharge electrode, a burner, and a chill-roller for supporting the plastic material.

Polymer films, such as polypropylene and polyethylene, having improved surface adhesion characteristics and produced by subjecting conventional polymer films to a heat treatment followed by a corona treatment at an energy density-to-film surface of at least 9 watt-minutes/ft.².

A method for producing a plate or sheet useful in planographic printing which is characterized in that the surface of an oleophilic body comprising oleophilic resin is subjected to a corona discharge treatment to form a hydrophilic layer on said surface, and that said method can be carried out without difficulty at a low cost and the reproducibility of the printing plate thereby produced is excellent.

A corona apparatus comprising at least one roller electrode assembly, a supporting surface acting as a counter electrode, and a generator for generating an alternating current voltage for said electrode assembly characterized in that the roller electrode assembly comprises: a central shaft, an electrode, means for mounting said electrode to said shaft, a tube, means for mounting said tube for rotation about said shaft, said electrode contained within said tube, means for electrically connecting said electrode to said generator and means for supporting said shaft whereby said tube is positioned adjacent to said counter electrode.

Two or more chemically dissimilar and non-compatible films may be bonded together to form a composite sheet by simultaneously subjecting them to high voltage electric corona discharge of selected intensity continuously through a critical region of mutual contact of the films. The critical region begins at the point at which the film surfaces to be bonded are not in contact with one another and extends at least to the point where all the films to be bonded are in mutual contact with their adjacent films.

A preferred film suitable for use as a wrapping material and obtained by the process of the invention comprises at least one layer of a polyolefin film and at least one layer of a film containing an acrylonitrile polymer.

Two or more chemically dissimilar and non-compatible films may be bonded together to form a composite sheet by simultaneously subjecting them to high voltage electric corona discharge of selected intensity continuously through a critical region of mutual contact of the films. The critical region begins at the point at which the film surfaces to be bonded are not in contact with one another and extends at least to the point where all the films to be bonded are in mutual contact with their adjacent films.

A preferred film suitable for use as a wrapping material and obtained by the process of the invention comprises at least one layer of a polyolefin film and at least one layer of a film containing an acrylonitrile polymer.

A corona discharge device is disclosed in which a cylindrical shell made of a dielectric material is mounted around a rotatable axle. Electrodes are arranged inside and outside of the shell so as to provide a corona discharge across a material to improve its surface qualities. A method of corona discharge treatment with the above apparatus is also disclosed.

Process and product-by-process of selectively treating a surface of plastic film to prevent blocking by blanketing the surface with a noble gas and by striking a corona discharge within the noble gas atmosphere, while the other surface of the film is in contact with some other gas or gas composition, such as air.

Disclosed is a device for the surface treatment of film webs by means of an electrical corona discharge, comprising: at least one grounded counter-electrode comprised of a point electrode; at least one roll electrode rotatably positioned adjacent to said counter-electrode, the roll electrode comprising an outer tube comprised of dielectric material, an inner tube comprised of dielectric material fitted coaxially inside of the outer tube and a plurality of electrodes carried by the inner tube; and a supply of A.C. voltage for the electrodes.

Plastic surfaces are treated with electrical corona discharge in an atmosphere of nitrogen and carbon dioxide. Oxygen is substantially excluded, and is kept at less than 0.1% by volume.

Apparatus for the corona discharge treatment of a travelling web such as a plastics or cellulose film comprises a pair of spaced conductors with an associated alternating voltage power supply set at such a distance apart that the possibility of spark or arc discharge is avoided, at least one conductor having mounted thereto an electrode member extending towards the other conductor to define a gap across which a corona discharge can be formed. The electrode member consists of a dielectric material having a dielectric constant of at least 8, preferably at least 80, and may consist of a plate with an edge directed towards the other conductor. Preferably the plate is formed of one or more ceramic tiles based upon a titanium and/or zirconium compound. In another form the electrode member consists of a row of rods or two or more rows of spaced rods in staggered relationship.

The invention provides a novel method for preventing bleeding of a plasticizer or other additive ingredients contained in a shaped article of a vinyl chloride-based resin composition on to the surface of the article by the treatment with low temperature plasma. Different from conventional procedures for the plasma treatment, much improved reliability and reproducibility as well as effectiveness are obtained by subjecting the article to intermittent exposure to the plasma atmosphere instead of continuous exposure. In the inventive method, the overall treatment time is an alternate sequence of exposure times, each being of the length of 0.001 second to 1000 seconds, and repose times, each being also of the length of 0.001 second to 1000 seconds. The gas for the plasma atmosphere is desirably an inorganic gas selected from the gases other than oxygenic gases, halogen containing gases and sulfur containing gases.

An apparatus for corona effect surface treatment of sheet materials, comprising a metal electrode and an insulating material coated electrode, between which the materials to be treated are inserted, wherein in the inside of said coated electrode a cooling fluid is caused to flow.

The present invention relates to improvements in treatment rolls for the corona discharge treatment of polymeric films whereby the same are rendered receptive to printing inks and the like. More particularly, the invention is directed to a treatment roll and method for use as an electrode in a corona discharge device, the roll being comprised of a metal substrate having a porous ceramic coating, the interstices in said coating being filled with silicone polymer, the roll evincing a high resistance to wear and electrical breakdown, whereby higher volumes of material may be processed.

Surfaces of hydrophobic polymers are treated to reduce their friction resistance characteristics when in contact with an aqueous environment by exposing the surfaces to an oxidation treatment, preferably by use of radio frequency glow discharge. This oxidation is followed by exposure to atmospheric air, until there is a substantial reduction in the air-water contact angle of the surfaces. The reduced friction resistance characteristics are important in aqueous applications where there is movement between the surfaces of two polymeric materials, such as in double slideable catheters and similar medical products. This process also provides lower coefficients of friction for general polymeric products in contact with water and aqueous solutions.

The apparatus for the electrical pretreatment of foils to increase the surface tension (surface energy) comprising a roller electrode forming a counter-electrode and over which is passed the foil to be treated, and at least three knife electrodes, which are arranged parallel to one another and at right angles to the direction of movement of the foil. The discharge edges of the knife electrodes have a constant spacing from the roller electrode surface, which leads to a much better treatment result.

A corona treater includes an active electrode which has one or more insulated electrode elements slidably supported by an insulating track. A contact spring connects each electrode element to a conductive electrode bar embedded in the track, and sheet material to be treated is fed through a treatment zone created between an active discharge surface on each electrode element and a bare metal roller electrode.

Compression rolling of a film is improved by subjecting the film to corona discharge prior to the rolling. The corona discharge treatment improves the processability of the film.

A corona discharge device includes a roll formed of a conductive material and a plurality of segments mounted on a support and arranged in spaced relation from the surface of the roll in an alignment generally parallel to the roll's rotational axis. Each segment includes a hollow insulator having an outer surface adapted to be disposed adjacent to said roll and a wall extending away therefrom. The conductive body is disposed within said insulator and in an opposed relation to said outer surface. The conductive means is coupled to the conductive body and extends outwardly from said insulator for being coupled to said support means for movement of said segment away from said roll. An insulating material can be used to fill the remaining portion of said insulator and to surround said conductive means.

A method for surface treatment of a substrate made of thermoplastic plastic is described, wherein the substrate is guided into the zone of a corona discharge flowing between two electrodes charged with high electrical voltage. The characterizing feature of the method comprises subjecting at least one surface of the substrate, simultaneously with corona treatment, to reactive ionized substances from the the liquid phase in the corona discharge zone.

In addition, a device for working the method recited hereinabove is described, comprising a support surface and a high-voltage electrode, said electrode being connected to a high-voltage generator via a high-voltage cable. The characterizing features of the device comprise the high-voltage electrode being a shaped electrode open toward the supporting surface, which is filled with a liquid.

Physical method for the treatment of the surfaces of polyolefinic plastic laminates, polytetrafluoroethylene (PTFE), cardboards and metal sheets such as, particularly, aluminium and tinplate, of any thicknesses and widths, by means of a flame produced by the combustion of a mixture of air-hydrocarbon gas, characterized in that such a mixture is enriched with pure oxygen gas.

There is provided a series of testing formulations or solutions which enable one to determine the critical surface tension or wettability of various solids, semi-solids and viscous liquids by application of the testing solutions to the surfaces of such materials or substrates. The solutions consist of a main solution which is 45 percent purified water and 55 percent of a dihydric alcohol such as ethylene glycol. This basic combination has a wetting tension of 56 dynes and has a completely neutral ph, and a neutral relative polarity. To vary surface tension, a non-ionic surfactant is added in ranges from about 1.5 percent to 0.001 percent by weight of the solution. In this manner the surface tension of each solution is varied in equal or predetermined increments. A dye is also employed to provide good contrast when the solution is placed on a test substrate. The percentage of dye can vary between 0.1 to 1 percent by weight depending upon the particular dye used. Due to the nature of the test solution provided, one can now perform wettability tests on various surfaces which could not be accommodated by prior art techniques. Each of the solutions employed have identical ph, identical viscosity, while further possessing the same neutral relative polarity.

A method for checking the degree of plasma treatment of an article. The method comprises depositing a substance able to change color as a result of plasma treatment on a carrier, the carrier having pores having an average pore size of 0.2-3 μm, placing the carrier having said substance deposited thereon near the surface of the article, subjecting the substance carrying carrier and the article to plasma treatment, and evaluating the color change that has occurred in the substance.

A process for surface modification of oriented polymeric film is disclosed. The process, applicable to polyesters, polyolefins, and polyamides, involves subjecting the film surface to at least one short pulse of intense electromagnetic radiation. Such surface treatment enhances the heat seal adhesion of the oriented polymeric film.

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.

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.

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

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.

The process of the present invention is for the surface treatment on both sides of a substrate by means of electric corona discharge, while simultaneously treating both surfaces of the substrate with a carrier gas/aerosol mixture introduced into the corona discharge zone. The arrangement for carrying out this process comprises a corona discharge device, consisting of a generator, high voltage electrodes, to which alternating current is applied by the generator, as well as grounded counter electrodes, a device for the atomization of liquid into a suspendable aerosol, which is connected via a transport line for the aerosol to the corona discharge device, and a blower, which is connected to the atomizer device and conveys the carrier gas/aerosol mixture to the corona discharge device. The electrodes and counter electrodes together form a gap for the substrate to be treated.

Moldings having a thickness of 1 to 60 mm and made of flexible webs or rigid sheet of plastic are passed through a corona discharge treatment system consisting of high-voltage electrodes and a counter-electrode and a high-frequency alternating current voltage of 20 to 25 kHz and 20 to 70 kV is applied to the high-voltage electrodes by a generator. A corona discharge forms in the gap between the high-voltage electrodes and the counter-electrode. An aerosol formed by atomizing a liquid is blown into the corona discharge zone by means of an air or gas stream. The aerosol modifies the surface of the sheet-like molding in the desired manner.

An object of the invention is to present a corona discharge processing apparatus capable of performing uniform and excellent corona discharge processing, on work of any thickness or shape, with the constant processing effect regardless of a thickness and shape of the work. A corona discharge processing apparatus of the invention comprises an excitation electrode and a counter-electrode, and generates a corona discharge by applying a high voltage between them, thereby applying corona discharge processing on the work, wherein the excitation electrode and the counter-electrode are both disposed on the same surface of the work with an interval between them.