Abstract: Fine paper that is sized with a 2-oxetanone alkaline sizing agent and that does not encounter machine feed problems in high speed converting or reprographic machines, including continuous forms bond paper and adding machine paper, processes for converting the paper into envelopes, continuous forms bond paper and adding machine paper, and paper products of the processes.

Abstract: A bag for packing a light-sensitive material is disclosed. The bag has an outermost surface and an innermost surface and is essentially consisting of a material for making the bag which comprises not less than 70% by weight of polyethylene and 1 to 10% by weight of a light shielding material based on the weight of the material, in which a Vicat softening point of the outermost surface is higher by not less than 20.degree. C. than a Vicat softening point of the inner most surface. Further a method for producing a bag is disclosed.

Abstract: A method and apparatus for gripping a bag and downstream handling, such as application of a header label to the bag. The bag, which has previously been filled with a product, is presented to the apparatus at an upstream bag presentation and accepting station and is gripped proximate its top. It is then transferred from the upstream bag accepting station to a downstream bag release station. Before being released, the bag travels to an intermediate label application station where a label is readied, the label then being transferred upstream to a second position and applied to the bag. Thereafter, the bag proceeds downstream, with the label, and the label is sealed to the bag. A series of grippers are employed for accepting a stream of discreet bags in a continuous manner. The grippers are recirculated continuously so that the apparatus operates continuously so long as bags are presented for application of a label.

Abstract: An apparatus and method for producing zipper closure bags from a continuous tube which includes advancing the tube along a continuous path for travel with a rotating metering roll, the metering roll having circumferentially spaced apart ports corresponding to a bag width, and a receiving conveyor having vacuum port-equipped sealing bars for receipt of the tube from the metering roll and for providing across seals defining adjacent paths.

Abstract: The invention has to do with the modification of well known heat sealing bag machines to increase the production capability of the machines. The use of servo drives for selected components of the bag machine permits the reduction of film acceleration and consequential peak film velocity, thus allowing faster machine cycles at the same film acceleration and consequential film velocity.

Abstract: An arrangement in a bag-making machine for forming weld lines in a web continuously fed through the machine, preferably a flattened plastic film tube, comprises a cylindrical, freely rotatable drum; a driving belt which is adapted to rotate the drum and pressed against part of the circumferential surface of the drum; and a number of transverse sealing jaws which, as the drum rotates, are movable into engagement with and drivable together with the web for welding the web through a predetermined angle of drum rotation. In order to achieve a high speed of the web, preferably about 150 m/min., and high flexibility in respect of the available range of bag length, the sealing jaws are freely movable relative to the drum outside the circumferential surface thereof and controlled by a control device which is adapted to hold each sealing jaw in a stand-by-position out of engagement with the web, and successively to bring each sealing jaw into engagement with the web with a certain time delay relative to each other.

Abstract: A method and apparatus for manufacturing sacks, made of polyethylene or other heat-sealable material, obtained by superposing two films or sheets which are unwound from respective rolls and are submitted to a pair of longitudinal welds to form a tube, and to transverse welds cuts. The edges of one of the sheets are formed with a re-entrant fold whereby the edges will overlap, with a portion of their outer faces, corresponding portions of the inner face of the other sheet. When only one of the sheets is folded at the edges, the welding of the overlapped end portions is effected by a single respective sealing bar acting on the outer face of the edges to be joined and having an opposite stationary contrasting member.

Abstract: A machine for the continuous production of plastic bags utilizes a servo drive motor to drive the machines film web draw roll assembly and through a seal roll index gear also to drive a seal roll of the machine in coordination with the servo driven draw roll.

Abstract: Heated seal bars are located on opposite sides of an elongated strip of heat sealable material adapted to be advanced with a step-by-step motion. When the strip dwells, the bars are shifted linearly inwardly into engagement with the strip to form a heat seal and then are retracted linearly a short distance away from the strip to permit the strip to advance through its next step. If an abnormal condition prevents the strip from advancing, the bars are retracted linearly to a parked position in which the bars are spaced a substantial distance away from the strip in order to prevent the heat radiating from the bars from damaging the stopped strip.

Abstract: An apparatus is provided for continuously sealing a thermoplastic draw tape to a thermoplastic bag at a sealing section. The bag forms one of a plurality of bags formed on a continuous web of thermoplastic material. The bag includes a hem defining a channel wherein the draw tape is disposed. The section of the bag which includes the hem and the tape thus includes a plurality of layers of thermoplastic material. The apparatus comprises a conveyor for continuously moving the web; a first sealing station for forming a heat seal through at least two of the layers of the hem and tape, the seal being formed on a first side of the bag; and a second sealing station for forming a heat seal through the rest of the layers of the hem and tape at the sealing section on a second side of the bag. The first and second sealing stations form the seals while the web is continuously moved by the conveyor.

Abstract: An apparatus and method for manufacturing reclosable thermoplastic containers which eliminates the need for spot-sealing zipper closures or zipper closure elements to a web of thermoplastic film prior to forming side seals and zipper end seals is provided. Opposing seal jaws provide increased heat and pressure to zipper closures in a manner which results in improved hermetic and fluid-tight side seals and zipper end seals.

Abstract: A device for assuring substantial smoothness in bags formed on a form, fill and seal machine comprising structure engageable with a closure along one edge of flattened bag making material below a forming and filling tube, and cooperating members operating cyclically from a position at the stabilizer in a flattening stroke across the material. The flattening members are desirably rollers which may be heated to effect a flatness retaining seal across the flattened material.

Abstract: An apparatus for controlling machines for making bags or sacks severed by welding from continuous tubular or semitubular films of synthetic thermoplastics has at least one pair of pinch rollers for feeding the continuous film. The pinch rollers are driven via a transmission by a first motor. A pair of welding jaws provides the continuous film with seam welds, transverse seam welds or severed transverse seam welds. A second motor actuates the welding jaws via a drive mechanism. A central processing unit controls the motors in such a manner that the motor for the pair of welding jaws is energized at a time when the motor for driving the pair of pinch rollers is still driving the pinch rollers, and after a standstill phase of the motor for driving the pair of pinch rollers the latter motor is energized even before the motor for driving the pair of welding jaws has stopped.

Abstract: A machine for the continuous production of plastic bags utilizes a servo drive motor to drive the machines film web draw roll assembly and through a seal roll index gear also to drive a seal roll of the machine in coordination with the servo driven draw roll. Control of the servo motor is through a motion controller receiving inputs form the servo motor.

Abstract: Seals are formed in bags made from a flexible web. The sealing element is a heated wire. The thermal conductivity of the wire is selected in reference to the melt and tack characteristics of the film being sealed such that when the film is placed in heat-exchange relationship with the wire, the film is sealed. Further, at least a portion of the film travels on the sealing element. The resistance across the sealing element remains constant during sealing and while the web travels sequentially.

Abstract: A vertical form, fill, seal machine for continuously making filled three sided fin pouches is disclosed herein. Mechanisms for controlling the thermoplastsic web so that the seals are improved are disclosed. One of the mechanisms ensures that equal lengths of web are fed into the sealing jaws. The other mechanism that is carried by the jaws grasps and tensions the web immediately before and during the sealing of the web.

Abstract: A process for the production of bags from thermoplastic synthetic resin sheeting with a bottom seam and/or a lateral seam fashioned as a cutoff weld seam obtained by severing tubular film sheets in the bottom zone, wherein there is produced by heat contact welding, at a station upstream of a transverse seam cutoff welding of the bottom seam or lateral seam, a wide flush weld seam over the entire width of the tubular film sheet and/or of the bag bottom to be produced, and subsequently the transverse cutoff weld seam is formed over the flush weld seam, extending within the flush weld seam.

Abstract: The rotary bag making machine of the present invention is adapted to make side seal bags having a plastic drawstring through a hem in the top of the bag. More specifically. The rotary bag machine of the present invention includes a two part, elongate sealing bar having sealing edges, the first part of which is heated to a first temperature for sealing two layers of plastic bag material and the second part of which is heated to a second higher temperature for sealing the six layers which are present when hems are formed with inserted drawstrings. The second part of the seal bar is not only designed to form the seal but to heat weld together the drawstring plastic so that it will not separate or tear apart when the bag is gathered and subsequently tied with the drawstring.

Abstract: An apparatus and process to permit high speed continuous motion heat sealing in the transverse direction of a moving, multiple layer web of polyethylene film. The apparatus includes a circular drum with a heated seal bar mounted flush with its cylindrical surface. The web of film wraps around the cylindrical surface of the drum and moves at the same speed. The web is pressed against the cylindrical surface by a least one rubber nip roll and is heat sealed in the area of the seal bar. The invention is particularly adapted for presealing the ends of the drawtape in the manufacture of drawtape bags.

Abstract: Apparatus for heat sealing the respective layers of film in a pair of hems in a moving web of film in the manufacture of draw tape bags. A pair of hot air hem sealer units is provided each of the units including a hot air hem sealer heat exchanger having a plurality of nozzles which direct hot air against a continuously moving film. The nozzles are in line with film movement and the film is backed up by a metal plate positioned between the hems. Following the heating phase cool compressed air is directed against the film in the heated area to cool the film prior to contact with the hem seal on the other side of the bag. The heat exchanger includes a plurality of circumferential grooves which deliver hot air to the nozzles. A thermocouple controls the temperature of the hot air.

Abstract: An oscillating sealing wire for high speed sealing of thermoplastic film. The sealing wire curved in the shape of a bow rocks back and forth across the moving surface of a thermoplastic film so the wire continuously presents a hot surface to the film. The film removes heat from the wire surface which touches the film. The oscillating wire continuously presents a new hot surface to the film to allow high speed movement of the film and still obtain a good seal.

Abstract: A plastic film product manufacturing apparatus includes a pair of draw rollers advancing a continuous length of plastic film, a plurality of guide rollers guiding the plastic film through at least part of the apparatus to the draw rollers and an endless flexible belt driving each of the guide rollers at a circumferential surface speed equal to the speed of the continuous length of plastic film advanced over the guide rollers. When the continuous length of plastic film is intermittently advanced by the draw rollers, and the guide rollers are simultaneously intermittently rotated by the endless belt. A primer mover drives both the draw rollers and the endless flexible belt to coordinate rotation of the draw rollers with the rotation of the guide rollers. One of the guide rollers is mounted on a dancer arm and a system of pulleys is provided for driving that guide roller by the endless flexible belt.

Abstract: An apparatus and method of handling flexible foldable materials, particularly thermoplastic film webs, continuously fed from a supply by continuously moving input nip rolls to a dancer including a roll mounted for movement transversely to its central axis. Intermittently moving draw rolls intermittently advance material from the dancer roll. The dancer roll is reciprocated in coordination with the intermittent advancement so as to decouple the translational inertia of the dancer roll from the material. A flexible belt also simultaneously rotates the dancer roll so as to decouple rotational inertia of the roll from the length of material. The dancer may be driven by a cam in common with a work station reciprocating against the material fed from the dancer.

Abstract: A draw tape bag forming apparatus includes an edge folder for folding the edges of pliable plastic web to form a hem in the edge. A draw tape is fed into the open hem which is then heat sealed along the inner edge of the hem wall to form a tubular hem. The web is of an indefinite length and moves continuously through the machine. The heat sealed hem is an expanded air-filled type hem. An electrostatic generator unit is mounted downstream of the ballooned hem. The generator unit includes a charging bar mounted in spaced relation to reference ground plate to form a gap with the ballooned hem passing therebetween. The hem is aligned with the bar. A 120 volt power supply is connected to the charging bar and establishes a high voltage along the length of the bar.

Abstract: A draw tape bag apparatus passes a web of plastic material having edge notched hems in the opposite edges to receive closing tapes. A hem sealer unit seals the folded layers of the web longitudinally of the folded edge to form the hem. The sealer unit includes a drum unit rotatably mounted on a shaft. The drum unit includes first and second drum parts having coaxial peripheral surfaces. A heat concentrating and release tape is secured to each drum part. The adjacent intermediate ends of the drum parts have telescoping and mating fingers and receses. Separate adjustment screws are coupled to the machine frame adjacent each drum part. Each screw is coupled to the outer race of a ball bearing secured to the adjacent outer end wall of the drum part. The setting of the screw accurately locates the heat concentrating tape axially of the drum. Hot air nozzles are mounted externally to the drum parts in alignment with the tapes and heat the web passing over the tapes to heat seal the web layers in the hem.

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: A bag making machine having a combination of a first dancer with multiple-rolls and a second dancer with a single roll for accumulating a web of flattened tubular thermoplastic material between constant and intermittent web feed sections of the bag making machine.

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 chain of bags is disclosed, with each having first and second panels and gusseted sides. The chain of bags is provided with a transverse bottom seal which in the central portion seals together the front and rear panels, and also seals together the inner portion of the gussets as well as the front and rear panels for four thicknesses being sealed. At the outer portions, there are only two thicknesses sealed together, namely, the front gussets are sealed to the front panel and the rear gussets are sealed to the rear panel. This establishes a chain of bags which may be supplied to a bag filling machine whereat conveyor belts form a nip and grip only the outer portion of the rear gussets where attached to the rear panel. By this means, the bags of a chain may readily be opened to practically full capacity and then filled. When the bag is closed and sealed, it forms a rectangular bag with square ends which may readily be palletized to form a secure and stable pallet load.

Abstract: Apparatus and method for ultrasonically bonding a web utilizes ultrasonic bonders having respective anvil and sonotrode components which are synchronously orbited with each other and with the rotation of a rotatable drum which carries the web of material to be bonded. One of the anvil and sonotrode components is orbited exteriorly of the drum and the other interiorly of the drum and they are brought into facing alignment through openings in the drum to clamp segments of the material therebetween during passage through a bonding segment of the travel path of the web about the drum. The bonder component orbiting exteriorly of the drum is axially translated away from the anvil along the drum in order to provide clearance for withdrawal of the bonded material from the drum. In this manner, an ultrasonic bonder may clamp the material at a single location for a large segment of its travel along the rotation path of the drum, thereby attaining a bonding time not limited entirely by the travel speed of the web.

Abstract: An improved thermoplastic film heat bonding apparatus includes a heated seal bar, a support member supporting the heated seal bar for reciprocating motion against a platen and a resilient coupling between the support member and the heated seal bar to allow deflection of the heated seal bar with respect to the support member providing better conformance between the platen and the face of the seal bar contacting the platen for more uniform and repeatable heat seals. Springs are used to provide the resilient coupling between the support member and the heated seal bar. One mounting providing both resilient coupling and continuous adjustable spacing between the support member and the heated seal bar includes a bracket supporting a threaded member passed through the support member and a coil spring biasing the bracket and support member apart. The bracket is itself resiliently mounted to the heated seal bar also by compression coil springs.

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 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 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: 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 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: Longitudinal welding equipment in a machine for packaging products fed on a conveyor belt inside a continuous film of plastic material wrapped around the products with overlapping longitudinal side edges. The equipment comprises a longitudinal welding means positioned above the edges of the means for generating an oscillatory rotary-translational motion on a vertical plane. Furthermore, the equipment provides at least one pressure and accompanying belt a top of the products wrapped inside the film. The welding means and the pressure belt are operatively driven by the same central motor means which actuates said conveyor belt. The welding means is equipped with a means for temperature control operatively connected to the packaging speed.

Abstract: A sealer is disclosed for sealing upper and lower portions of a web without sealing the portions together, such as side gussets in side gusseted bags. A sealing bar is placed below the web and fixed with respect to the machine. Another sealing bar is placed above the web, parallel to the first one. An air cylinder can urge the upper sealing bar down against the lower one to seal the web. A platen is placed within the side gusset to prevent the portions from being sealed to each other, and the platen floats vertically to accommodate the motion of the sealing bars.

Abstract: A method and an apparatus for heat welding a butt seam on a tube of packaging material, in which the welding heat is generated by applying a high-frequency alternating electromagnetic field of a pair of induction coils. To prevent current arcing at the cut edges of a metal inlay of the packaging material in the vicinity of the abutting edges of a sheet of packaging material, the edges are guided spaced apart from one another by a predetermined distance. To this end, the apparatus has a separating blade, which in the operative range of the electromagnetic alternating field protrudes in between the abutting edges of the sheet of packaging material and between the induction coils.

Abstract: A plastic separable fastener strip, and assembly of such strip with a substrate, and a method of attaching such strip to a substrate, comprising the provision of and utilization of fusible ribs on the base surface of the fastener strip to provide a bonding layer for bonding the strip to the substrate. Reducing the ribs into fusible condition without heat distortion of the remainder of the fastener strip and without heat distortion or damage of the substrate, provides a bonding layer when the fused ribs of the fastener strip are pressed together with the substrate. A simple apparatus and method are provided for effecting the bonding by fusion of the fusion ribs.

Abstract: An apparatus for transversely sealing layers of thermoplastic material wherein platen-equipped upper and lower cross bar conveyors are provided for the sealing, there is provided means for jogging the thermoplastic web material incident to heat-up of the platens to prevent scorching of the web and means for stretching the layered web during sealing to overcome the tendency for differential longitudinal shrinkage.

Abstract: This invention is an improved heatseal die that forms superior airtight seals. The die has opposed die faces, with one die face having longitudinal lands and the other die face having grooves for receiving the lands. The lands are truncated and the depth of the grooves is greater than the height of the lands. As a result, the force applied by the lands and grooves is applied entirely as a shearing force, which forms the superior heatseals.

Abstract: An apparatus for manufacturing pocketed coil springs is provided. The apparatus includes a pair of weld heads and an adjustment assembly for moving the heads longitudinally or transversely from each other. The relative position of the weld lines in a fabric passing beneath the heads can accordingly be set with precision. This is accomplished by rotating one of the heads about two axes, one extending through the head and a second axis extending parallel to the first at a selected distance therefrom.

Abstract: For producing transverse seams on tube bag machines, two conjointly, oppositely moving sealing tool jaws (15, 16) are provided, which are movable on a carriage (6) during the sealing process.For driving the sealing tool and selecting an appropriate stroke length, the frame (5) on which the carriage (6) rests is movable up and down by a pair of coupled cam-actuated levers (19). The axes of rotation (34) of two levers (19), and thus the distances travelled by their uncoupled, flapping ends, are adjustable along the lengths of the levers. This is accomplished by turning a spindle (3) bearing oppositely wound screw threads, which sets adjustment bodies (30) with sliding blocks (4) for the two-armed levers (19).Thus, packages of varying heights can be efficiently sealed, since the sealing mechanism always seals in the middle of the package height, regardless of stroke length selected.

Abstract: Multi-layered enclosures are provided which include extruded tubing laminated between two extruded sheets of coextruded film in order to rapidly produce an unusually tough enclosure having longitudinal side walls that are free of internal seams while providing superior fluid barrier properties. When desired, the multi-layered enclosure is transformed into a multi-layered bag or pouch by sealing the multi-layered enclosure together along one or more locations interconnecting the longitudinal or side edges of the multi-layered enclosure to thereby cross seal together the sheets, the tubing, and the internal surfaces of the tubing.

Abstract: Apparatus for forming transverse seam welds or separated seam welds in plastic film webs, preferably for making bags, with a transverse welding device having jaws cyclically opened and closed and between which the film web is intermittently advanced when the jaws are open and is held in position during the welding times, and a rocker lever, which by a cam slot and a slide block imparts to the transverse welding device or to the film web a movement in the same or opposite direction to each other, which movement is derived from a rotating eccentric cam wheel.

Abstract: Multi-layered enclosures are provided which include extruded tubing laminated between two extruded sheets of coextruded film in order to rapidly produce an unusually tough enclosure having longitudinal side walls that are free of internal seams while providing superior fluid barrier properties. When desired, the multi-layered enclosure is transformed into a multi-layered bag or pouch by sealing the multi-layered enclosure together along one or more locations interconnecting the longitudinal or side edges of the multi-layered enclosure to thereby cross seal together the sheets, the tubing, and the internal surfaces of the tubing.

Abstract: A pneumatic-electromagnetic latch is disclosed as applied to bring the sealing jaws of an L-sealer into pressure engagement without impact. An electromagnet mounted on a piston rod of a pneumatic actuator attracts and retains an armature attached to the sealing jaws when the jaws are brought close to the sealing bed. The cylinder of the actuator is attached to the frame and when actuated it draws the sealing jaws into smooth pressure contact with the sealing bed. Upon deenergization of the electromagnet the jaws are released to open for the next sealing cycle and the release of fluid pressure in the actuator extends the piston rod to position for the next operation.

Abstract: Profiled heat seals in plastic film are provided by opposed profiled heat sealing platens supported on endless chains. The platens are heated by contact with associated heating drums.

Abstract: In the production of plastics bags, especially valved bags, from a web of plastics material by folding in the side margins of the web to form overlapping panels which are then longitudinally heat-sealed together for a major portion of one bag length, and then heat-sealing the web transversely and severing the web at intervals to produce individual bags, the two overlapping panels are heat-sealed together by forming two longitudinal seals which partially overlap to provide a forward longitudinal seal and a rear longitudinal seal with respect to the direction of travel of the web, the rear longitudinal seal of each bag being formed simultaneously with the forward longitudinal seal of the adjacent following bag. The apparatus comprises a pair of heat-sealing elements equipped for simultaneous operation and arranged for forming the rear seal in one bag and the forward seal in the following adjacent bag. The two elements may be a fixed distance apart, and at least one has suitably a hairpin shape.