Abstract: An apparatus for the manufacture of selectively apertured thermoplastic sheet or film, comprising a rotatable molding element means for receiving the film and which means has a predetermined pattern therein wherein as the film is contacted with the rotatable molding element means and a fluid pressure differential is applied to the surface of the film, a desired pattern of perforated areas and non-perforated areas are imparted to the film with each of said areas being continuous across the web of the film and alternating in the machine direction.

Abstract: An apparatus for the manufacture of selectively apertured thermoplastic sheet or film, comprising a rotatable molding element means for receiving the film and which means has a predetermined pattern therein wherein as the film is contacted with the rotatable molding element means and a fluid pressure differential is applied to the surface of the film, a desired pattern of perforated areas and non-perforated areas are imparted to the film with each of said areas being continuous across the web of the film and alternating in the machine direction.

Abstract: A laminated, cylindrical, metal screen or molding element for vacuum perforation of plastic film or sheets, comprising two or more relatively thin cylindrical metal screens, each having a predetermined inside and outside diameter and each having a plurality of openings or holes therein of a predetermined size and geometrical shape, and said relatively thin screens stacked and bonded together, diametrically one inside the other thereby providing a screen of a desired thickness and a desired hole geometry wherein the holes in the screen have substantially straight walls perpendicular to the surface of the screen. A method of producing a relatively thick cylindrical metal screen for vacuum perforation of plastic film or sheets wherein the holes or openings in the screen have substantially straight walls perpendicular to the surface of the screen, comprising stacking and bonding together two or more matched relatively thin metal screens diametrically one inside the other.

Abstract: A laminated, cylindrical, metal screen or molding element for vacuum perforation of plastic film or sheets, comprising two or more relatively thin cylindrical metal screens, each having a predetermined inside and outside diameter and each having a plurality of openings or holes therein of a predetermined size and geometrical shape, and said relatively thin screens stacked and bonded together, diametrically one inside the other thereby providing a screen of a desired thickness and a desired hole geometry wherein the holes in the screen have substantially straight walls perpendicular to the surface of the screen.A method of producing a relatively thick cylindrical metal screen for vacuum perforation of plastic film or sheets wherein the holes or openings in the screen have substantially straight walls perpendicular to the surface of the screen, comprising stacking and bonding together two or more matched relatively thin metal screens diametrically one inside the other.

Abstract: A sterilizable, preferably fiber-free, perforated packaging material which can be utilized to make a package to hold an item which can be sterilized while it is inside the package comprising a first layer of perforated thermoplastic film, preferably extruded film, and having at least one heat-sealable surface, and a second layer of perforated thermoplastic film, preferably extruded film and having at least one heat-sealable surface, the first layer being oriented relative to the second layer so that the perforations in both of the layers are mis-aligned and at least one of the heat-sealable surfaces of one of the layers contacts at least one of the heat-sealable surfaces of the other layer; a package made from the packaging material; and a method of sterilizing an item in a package.

Abstract: A laminated, cylindrical, metal screen or molding element for vacuum perforation of plastic film or sheets, comprising two or more relatively thin cylindrical metal screens, each having a predetermined inside and outside diameter and each having a plurality of openings or holes therein of a predetermined size and geometrical shape, and said relatively thin screens stacked and bonded together, diametrically one inside the other thereby providing a screen of a desired thickness and a desired hole geometry wherein the holes in the screen have substantially straight walls perpendicular to the surface of the screen.A method of producing a relatively thick cylindrical metal screen for vacuum perforation of plastic film or sheets wherein the holes or openings in the screen have substantially straight walls perpendicular to the surface of the screen, comprising stacking and bonding together two or more matched relatively thin metal screens diametrically one inside the other.

Abstract: An apparatus for the manufacture of selectively apertured thermoplastic sheet or film, comprising a rotatable molding element means for receiving the film and which means has a predetermined pattern therein wherein as the film is contacted with the rotatable molding element means and a fluid pressure differential is applied to the surface of the film, a desired pattern of perforated areas and non-perforated areas are imparted to the film with each of said areas being continuous across the web of the film and alternating in the machine direction.

Abstract: A perforated thermoplastic film with less than ideally shaped tapered capillaries which has an increased liquid flow rate through the tapered capillaries and a method for making such a film. The method includes forming a perforated thermoplastic film having tapered capillaries from a resin into which an effective amount of a polarizable, migrating surfactant has been blended therewith and then treating the perforated thermoplastic film with a corona discharge treatment sufficient to increase the flow rate of liquid through said perforated film and provide a film having a percent run off of from about zero to ten percent.The perforated film made in accordance with the invention has a much higher liquid transmission rate than similarly made non-surfactant treated perforated film having tapered capillaries which has been treated only with a corona discharge treatment. The latter may be conducted as the film is being formed and perforated.

Abstract: A perforated thermoplastic film with less than ideally shaped tapered capillaries which has an increased liquid flow rate through the tapered capillaries and a method for making such a film. The method includes forming a perforated thermoplastic film having tapered capillaries from a resin into which an effective amount of a polarizable, migrating surfactant has been blended therewith and then treating the perforated thermoplastic film with a corona discharge treatment sufficient to increase the flow rate of liquid through said perforated film and provide a film having a percent run off of from about zero to ten percent.The perforated film made in accordance with the invention has a much higher liquid transmission rate than similarly made non-surfactant treated perforated film having tapered capillaries which has been treated only with a corona discharge treatment. The latter may be conducted as the film is being formed and perforated.

Abstract: A perforated thermoplastic film with tapered capillaries which has an increased liquid flow rate through the tapered capillaries and a method for making such a film. The method includes subjecting a perforated thermoplastic film having tapered capillaries to a corona discharge treatment sufficient to increase the flow rate of liquid through said perforated film.The film made in accordance with the invention has a much higher liquid transmission rate than the perforated film of the prior art. Furthermore, the film may be treated with a corona discharge continuously as the film is being formed and perforated.

Abstract: A process for the manufacture of thermoplastic sheet having elliptical perforations including a rotatable molding element having a series of hexagonal-shaped depressions having centered therein elliptical holes, the elliptical holes having a major axis and a minor axis, the major axis being oriented parallel to the direction in which the molding element is rotated, a means for applying a fluid pressure differential to a surface of the thermoplastic sheet to force the sheet against the molding element to effect rupturing of the sheet and the formation of elliptical holes in the sheet.

Abstract: A process and apparatus for the manufacture of thermoplastic sheet having elliptical perforations, the process including placing a thermoplastic sheet into contact with a continuously rotating molding element having a series of elliptical holes therein in which the major axis of the elliptical holes is oriented parallel to the direction in which the molding element is rotating, subjecting a surface of the thermoplastic sheet to the action of a fluid pressure differential to cause the material to flow into the elliptical holes of the molding element while maintaining the pressure differential to effect rupturing of the thermoplastic sheet and the formation of elliptical holes in the sheet, and continuously removing the molded portions of the thermoplastic sheet from the molding element.

Abstract: A rotating joint assembly for feeding an extrusion die with two or more thermoplastic layers of a consistent uniformity of distribution including a stationary manifold for receiving two or more thermoplastic streams and conveying the streams to discharge openings in the manifold, and a cylindrical conduit rotatably connected to the manifold, the conduit having intake openings aligned with discharge openings in the stationary base for receiving and conveying thermoplastic streams from the base to an extrusion die and an axial channel aligned with an axial channel in the stationary manifold for receiving and conveying one of the thermoplastic streams to the die.

Abstract: A rotatable perforated molding element for embossing and/or perforating thermoplastic sheet or film, the molding element including a series of perforated strips having two parallel sides and two parallel ends, the strips being wrapped about a supporting drum in a manner such that the ends of the molding strips lie in a plane generally perpendicular to the axis of rotation of the molding element and the sides of the adjacent strips contact each other, and a method for connecting the rotatable perforated molding element to a supporting drum including wrapping a series of perforated strips having two parallel sides and two parallel ends about the supporting drum in a manner such that the ends of the molding element lie in a plane generally perpendicular to the axis of rotation of the molding element and the sides of the adjacent strips contact each other, and securing the ends of the strips to the drum.

Abstract: A rotatable perforated molding element for embossing and/or perforating thermoplastic sheet or film, the molding element including a series of perforated strips having two parallel sides and two parallel ends, the sides being perpendicular to the ends, each of the strips being welded at the end prior to placing the strips on a supporting drum. Additional strips are placed on the drum until the desired area of the drum is covered with the strips.

Abstract: A method for embossing thermoplastic material and the thermoplastic material produced thereby. A transverse section of a continuous length of preformed thermoplastic film is heated by a nondirect contact heat source to raise the temperature of the film above its softening point. The film is then fed immediately between adjacent, counter-rotating embossing rollers, thereby embossing a raised pattern onto the film. The rollers are cooled to fix the embossed pattern on the film. The embossed film has good moduli, low surface gloss or light reflectance, deep embossed pattern, high tensile strength and high impact strength.