Abstract: A thermoplastic draw tape bag having a microencapsulated adhesive on the inside surface of each hem of the bag. The adhesive has the characteristic that when the draw tape is withdrawn from the hem thereby causing the hem to gather, the tape pulls easily until it is tight whereupon further pulling of the draw tape causes the adhesive capsules to be broken thereby gluing together the tape and the hem and holding the bag closed.

Abstract: A thermoplastic draw tape bag having a tacky coating on the draw tape at the secured end thereof and extending for a fraction of the length of the draw tape. The tacky coating comprises a material having the characteristic of sticking to itself and being adapted to cling to the inside of the hem when the uncoated length of the draw tape is withdrawn from the hem causing the hem to gather and hold the bag closed after the draw tape is pulled tight thereby preventing the bag from inadvertently coming open. The tacky coating on the draw tape may comprise a coating of glycerol mono-oleate or a layer of polyvinylidene chloride or a layer of polyisobutylene.

Abstract: An oven-heated hot wheel sealing unit for heat sealing thermoplastic film. The unit includes an oven having a heater for heating the air therein. A plurality of rotors are rotatably supported within the oven. Each of the rotors includes a wheel having a rim adapted to extend outside of the oven for engaging the thermoplastic film to be heat sealed. Each rotor has a plurality of spaced fins disposed axially thereof and parallel to the wheel. Stators are positioned within the housing and provided with structure to receive the fins on the rotors. The fins on the rotors have a plurality of vanes adapted to circulate the heated air within the oven for heating the wheels by convection. The rims of the wheels extend through openings in non-stick stripper shoes on the outsides of the oven for stripping the thermoplastic film from the wheels after heat sealing the film.

Abstract: In the manufacture of draw tape bags hems are formed in the opposing panels of the moving web of folded thermoplastic film by utilizing tucker bars, that tuck the hem for the draw tape bags, equipped with a series of rubber wheels that pull the film diagonally so that it is tight against the edge of the folding boards.

Abstract: A screw extruder and a method of operation thereof. The screw extruder comprises a barrel including a section that is supported for rotation about the longitudinal axis of the barrel. A screw extends and is supported for rotation in the barrel; and, in use, rotation of the screw rotates and advances plastic material through the barrel. Rotation of the screw also causes the rotatable barrel section to rotate, and a brake is connected to that rotatable section to maintain the rotational speed of the rotatable section less than the rotational speed of the extruder screw. The rotational speed of the screw relative to the rotatable barrel section controls the relative rates at which plastic is mixed, heated, and pressurized in the barrel.

Abstract: An apparatus for punching holes into sheet materials, and more particularly, a high speed punching apparatus of the so-called bullet punch type for the sequential punching of holes into an advancing web or sheet of paper, plastic or other film material through the intermediary of a high-speed projectile reciprocatively piercing through the material.

Abstract: A dual draw tape bag has a front wall and back wall of flexible sheet material joined to each other along edges of the bag. Tubular channels extend along opposed transverse top edges of the front and back walls. The channels define an open mouth for the bag. Each of the channels has openings at the opposite ends of the top edges of the bag. A pair of tapes extend through each of the chanels. One of the ends of each of the tapes is attached to the opposite side edges of the bag beneath the openings in the channels and the other ends of the tapes extend through the respective openings at the other end of the channels so that the tapes cross in the channels, whereby when the tapes are pulled, the top of the bag is drawn tightly together.

Abstract: This invention provides a reclosable flexible bag having a tape of greater thickness around its opening portion. On the surfaces of the tape facing the bag, fastener profiles are provided to seal the bag by pinching the bag walls therebetween.

Abstract: A draw tape bag with two single tapes has a front wall and back wall of flexible sheet material joined to each other along edges of the bag. Tubular channels extend along opposed transverse top edges of the front and back walls. The channels define an open mouth for the bag. Each of the channels has openings at the opposite ends of the top edges of the bag. A tape extends through each of the channels. One of the ends of each of the tape is attached to the opposite side edges of the bag beneath the openings in the channels and the other end of the tape extends through the respective opening at the other end of the channel so that the tapes cross in their respective channels, whereby when the tapes are pulled, the top of the bag is drawn tightly together. A method of forming this draw tape bag is also disclosed.

Abstract: A draw tape bag with two single draw tapes having a front wall and back wall of flexible sheet material joined to each other along edges of the bag. Tubular channels extend along opposed transverse top edges of the front and back walls. The channels define an open mouth for the bag. Each of the channels has openings at the opposite ends of the top edges of the bag. A pair of draw tapes extends through both of the channels. One end of each of the tapes is attached to opposite side edges of the bag beneath the openings in one of the channels and the other end of each of the tapes extends through the openings at the corresponding ends of the other of the channels so that the tapes cross each other in both channels and wrap around the mouth of the bag whereby when the tapes are pulled the mouth of the bag is drawn tightly together.

Abstract: A tumbling hole punch consists of a serrated tube plunging straight through a film web into a hole in a backup roll. The serrated punch is mounted to an arm which is geared to the backup roll so that the punch remains in register with the hole in the roll. In order to keep the axis of the serrated punch aligned with the axis of the hole in the roll, the punch pivots relative to its arm, and the pivoting is controlled by a gear belt drive so that as the arm rotates the punch tumbles in the opposite direction, keeping its axis parallel with the hole axis.

Abstract: A method of accurately punching holes into a moving web of a thermoplastic film material, and more particularly, punching holes into the web through the intermediary of a rotary serrated tube punch. The invention relates to accurately punching holes into an advancing web of thermoplastic film material utilizing a novel rotary serrated tube punch. The film web is continuously advanced over at least a portion of the circumferential surface of a rotatable anvil roll, and tensioned against the anvil roll surface through the use of suitable tensioning devices, such as tension rollers arranged upstream and downstream of the anvil roll. At least one opening is formed in the circumferential surface of the anvil roll which is smaller than the size of the hole which is desired to be punched into the film web through the use of the inventive rotary tube punching arrangement. An annular groove extends about the hole in the surface of the anvil roll, forming a land between the hole and the groove.

Abstract: Apparatus for sealing a hem in a moving web of plastic film having a structure including a folding surface having a web passing on one side of the surface and an edge of the web on the other side of the surface to produce a hem in the web prior to leaving the surface. Heat sealing apparatus is supported adjacent the structure for heat sealing the hem while the web is moving and prior to the sealed hem leaving the surface. The surface is provided with an opening in alignment with the heat sealing apparatus and the heat sealing apparatus seals the hem through the opening.

Abstract: Apparatus for producing a machine-direction heat seal in a moving web of plastic film including a block adapted to be supported on one side of the hem and having a plurality of rollers mounted thereon at spaced locations in tandem for engaging the film along the path of the heat seal to be formed in the hem. The block has a corresponding plurality of surfaces each of which is adapted to be engaged by a side of one of the rollers. A heater is provided for heating the block and its plurality of surfaces and the rollers are maintained in contact with the plurality of surfaces whereby movement of the hem though the heat sealing apparatus causes the plurality of rollers to rotate and maintain contact with the plurality of surfaces whereby the rollers are in turn heated by conduction from the block and produce the heat seal in the hem.

Abstract: Apparatus for heat sealing a hem in a moving web of plastic film using a plurality of rollers or wheels mounted on a block at spaced locations for engaging the film along the path of a heat seal to be formed in the hem. The rollers are heated by contact of one of their sides against a heated block. The small force holding the rollers against the heated block is provided by a slight angular orientation of the roller relative to the direction of film travel.

Abstract: Apparatus for producing a machine-direction intermittent heat seal in a moving web of plastic film including a block adapted to be supported on one side of the hem and having a plurality of wheels having heat conducting surfaces spaced around the periphery and mounted on the block at spaced locations in tandem for engaging the film along the path of the intermittent heat seal to be formed in the hem. The block has a corresponding plurality of surfaces each of which is adapted to be engaged by a side of one of the wheels. Gears interconnect the wheels to maintain the wheels in register with the intermittent portions of the heat seal in the hem during rotation of the wheels.

Abstract: Draw tape bags are made with folding surfaces which decrease in width to the final bag height. One edge of each side of a moving web of film is tucked onto a side of a surface to produce a hem in each edge of the moving web. Rollers, which are canted with respect to the direction of movement of the web, pull the hem of the film tight against the surface to insure that the web is at the final bag length when the web leaves the surfaces.

Abstract: Apparatus for heat sealing a pair of hems in a moving web of film having structure including a pair of spaced surfaces over which each hem of the pair of hems is adapted to pass. A first block is supported by the structure with respect to one of the surfaces and on one side of one of the hems. A plurality of rollers is mounted on the first block at spaced locations in tandem for engaging the film along the path of the heat seal to be formed in the one hem. A second block is supported by the structure with respect to the other of the surfaces and on one side of the second hem. The second block has a plurality of rollers mounted thereon at spaced locations in tandem for engaging the film along the path of a heat seal to be formed in the second hem. Heaters are provided for each of the blocks and the respective plurality of rollers whereby movement of the hems through the heat sealing apparatus causes the plurality of rollers mounted on the blocks to rotate and produce the heat seals in the pair of hems.

Abstract: A screw extruder comprises a barrel including a section that is supported for rotation about the longitudinal axis of the barrel. A screw extends and is supported for rotation in the barrel; and, in use, rotation of the screw rotates and advances plastic material through the barrel. Rotation of the screw also causes the rotatable barrel section to rotate, and a brake is connected to that rotatable section to maintain the rotational speed of the rotatable section less than the rotational speed of the extruder screw. The rotational speed of the screw relative to the rotatable barrel section controls the relative rates at which plastic is mixed, heated, and pressurized in the barrel.

Abstract: A method of accurately punching holes into a moving web of a thermoplastic film material, and more particularly, punching holes into the web through the intermediary of a rotary serrated tube punch. The invention relates to accurately punching holes into an advancing web of thermoplastic film material utilizing a novel rotary serrated tube punch. The film web is continuously advanced over at least a portion of the circumferential surface of a rotatable anvil roll, and tensioned against the anvil roll surface through the use of suitable tensioning devices, such as tension rollers arranged upstream and downstream of the anvil roll. At least one opening is formed in the circumferential surface of the anvil roll which is slightly larger than the size of the hole which is desired to be punched into the film web through the use of the inventive rotary tube punching arrangement.