FI83493C - Method and apparatus for making a plastic film with lockable sealing tape parts in the product - Google Patents

Description

1 83493

Method and apparatus for making a plastic film fused to resealable closure strips Förfarande och anordning för framställning av en plastfilm med i varandra läsbara tillslutningsbandsdelar

The object of the invention is to provide a plastic container with a resealable closure, and in particular a method and an apparatus for manufacturing a blank stock which can be used for the production of bag products with a lockable closure.

Plastic containers with resealable closures are generally known and are widely used by consumers and are also used in industry. Their popular use has strongly encouraged the development of better manufacturing equipment and methods for more economical operations, as well as the development of products that are more market-friendly.

A particularly desirable type of reclosable closure is described in U.S. Patent No. 4,212,337 (Kamp), in which the locking closure device comprises a first trough element having spaced apart hook portions and a second trough element having facing hook portions. The gutter elements are locked when the first gutter element is pressed onto the second gutter element so that the hook parts are locked together. This lockable closure device is attached to the opening of the container to form a container that can be closed and opened.

The blank for a plastic container is generally made of a film of injection molded polyethylene, polypropylene, nylon, or other thermoplastic material. Both closure elements of the closure device can be made as a strip, which is later attached to the film using suitable means. Thus, a thermoelectric device can be used to apply heat to a film in contact with the sealing strip, to cause heat to pass through the film to fuse the interface between the film and the sealing strip. The fusing of the film and the sealing strip can also be done using hot melt adhesives, hot melt sealing, or other methods such as ultrasonic heating. However, hot air sealing of the sealing strips to the film requires the inner side of the edge of the sealing strip to be adhered to seal the film. However, this additional material in the sealing strips does not significantly contribute to the performance of the tank, but increases its cost. In addition, the hot air-sealing technology currently available for this purpose results in limited production capacity. The hot air seals formed do not cover the entire edge of either sealing strip, which makes the edges quite visible and gives the resealable container the appearance provided by the addition of components.

In order to avoid the above-mentioned disadvantages, it has been proposed to fasten the lockable closure device to the film as described in U.S. Patent No. 4,106,924. This publication explains how to this casting cylinder so that the plastic film, before cooling, merges with the edges of the sealing strips. The casting cylinder has two spaced circumferential grooves so that the respective profile portions of the closure strips extend into these grooves. When melting plastic film, molding means are used to press the plastic film into the edges of the sealing strips. However, it has been found that the adjustment of such compression is difficult and can damage the profile parts of the sealing strips when these sealing strips are laminated with a molten plastic film. In addition, the molten slit cast film tends to thin in areas in the immediate vicinity of the lamination, causing weak areas.

Thus, there is a continuing need for a method and apparatus that can be used to make a plastic film combined with lockable closure strips, and resealable container blanks in which the aforementioned problems are avoided. According to the invention, this object is solved by the means defined in the appended claims.

According to an embodiment of the invention, there is provided an apparatus for producing a plastic film embedded with interlocking closure strips having profile portions and flanges, the apparatus having feed means for feeding the sealing strips, a rotatable circumferential grooving roll, a rotatable casting cylinder the shaft is parallel to the roll, means for advancing the sealing strips to advance to the matching roll such that the non-locking profile portions of the sealing strips extend into the grooves of the matching roll;

The mating roller has circumferential grooves as a means of bringing the sealing strips of arbitrary length at a suitable distance from each other and moving them towards the casting cylinder. The injection molding means is preferably a slot die with an elongate opening parallel to the circumference of the casting cylinder and spaced apart from this circumference. The die is suitable for casting a film of molten thermoplastic material on the circumference of a casting cylinder. There are means for rotating the casting cylinder at substantially the same surface speed as the speed at which the fed sealing strips are made to advance, whereby the sealing strips are laminated to a film of molten thermoplastic material which is cast on the casting cylinder. The combination of sealing strips and plastic film is then made to proceed to the second cooling means.

According to another embodiment of the invention, there is provided a method of making a plastic film 4 83493 fused to interlocking closure strips, each strip having profile and side portions, the method comprising the steps of extending into the grooves of the matching roll, the molten plastic film is injection molded onto a rotating casting cylinder located opposite the matching roll so that the plastic film merges with the edges of the sealing strips, and then the combination of plastic film and sealing strips is cooled.

In general, the operation of the present invention is based on causing a lockable closure strip in a non-molten state to adhere to a molten film of thermoplastic material. The process is continuous and uses a film slit casting station and a grooved matching roller. The locking closure strip usually has at least two profile parts and corresponding edge parts. One or more interlocking sealing strips are threaded onto a matching roller having grooves to which the outline of the sealing strip profile fits. After the edge portions of the sealing strips have been laminated to the molten slit-molded plastic film, the cooling roll further cools the laminate of the film and sealing strips. The device may also have cutters to remove debris, such as edging, and to cut the laminate to produce a plurality of products with closures.

In particular, according to a preferred embodiment of the invention, the concealable closure strips are fed into the grooves of a plurality of rubber-coated matching rollers, which rollers orient the strips to the correct lateral positions before coming into contact with and laminating the molten thermoplastic film. Each mating roll is only as wide as the part of the sealing strip to be laminated with the molten thermoplastic film in each case, and this roll does not normally touch this molten thermoplastic film. The lamination compression applied by the mating rollers to the casting cylinder and the intermediate sealing strips and to the molten plastic film is adjusted by means of spacers, such as adjusting bolts or air cylinders, to prevent damage to the profile parts of the sealing strips. Obviously, any desired number of such matching roller systems can be used on a single shaft, or the matching rollers can be placed on different shafts.

The nature and objects of the invention will be explained in more detail below on the basis of the accompanying drawings.

Figure 1 shows a schematic perspective view of an embodiment of the invention.

Fig. 1A is a schematic sectional view of a matching roller according to an embodiment of the invention.

Fig. 1B shows in schematic section a second embodiment of a matching roller according to the invention.

Figure 2 shows a side view of the matching roller and the casting cylinder and shows devices for adjusting the distance between them.

Figure 3 shows a locked closure strip laminated with a resilient resin 1.

Figure 4 shows a schematic perspective view of a preferred embodiment of the invention.

Figure 5 is a side view of a mating roll and a casting cylinder showing means for adjusting the lamination pressure between the sealing strip or strips and the thermoplastic film.

In the practice of the invention, several embodiments have been selected to illustrate them in the accompanying drawings, the figures of which are incorporated herein by reference.

According to Figure 1, an unlocked closure strip consisting of parts 1 and 2 is fed from a feed source (not shown), such as a discharge coil. The source of feed for the closure strip portions may be a roll of prefabricated sealing strips or a manufacturing site on the production line that supplies the sealing strip portions. The sealing strip portions are fed to spaced apart circumferential grooved separate mating rollers 3 and 4 rotatably mounted on a common shaft 11. The mating rollers are located opposite the rotatable casting cylinder 5, and the axis of the casting cylinder 5 is parallel to the mating rollers 3 and 4. A slit nozzle 6 with an elongate opening parallel to the shafts of the casting cylinder and the matching roll is located near the circumferences of the casting cylinder and the matching rolls at a distance therefrom for casting a film 7 of molten thermoplastic material on the circumference of the casting cylinder. The slit nozzle 6 is fed from the melt supply line 8. The film 7 of molten thermoplastic material is injection molded from the slit nozzle 6 onto the casting cylinder 5 and the film comes into contact with and seals the sealing strip parts 1 and 2 and forms a laminated connector 9. to a cutting and / or winding device, generally indicated by arrow 10.

Figure 1A illustrates another embodiment of the invention, in which the matching roller 3 is mounted together with the matching roller 4 on a common shaft 11, and these matching rollers 3 and 4 are axially movably mounted on the shaft. According to this embodiment, different distances between the matching rollers can be provided, and the closure strip portions 1 and 2 can also be fused laterally to any desired location of the film 7.

Figure 1B shows another embodiment of the invention using a single mating roller 43. In this embodiment, the single mating roller has two grooves into which the closure strip portions 1 and 2 fit. These grooves may be located at or near the ends of a single matching roll 43, and in this roll there may be a recess 44 between the grooves 7 to prevent contact between the molten film 7 and the matching roll 43. When a single alignment roller is used, this roller can have any desired number of grooves and recesses located at any location.

The elements shown in Fig. 2 are denoted by the same reference numerals as in Fig. 1. Fig. 2 shows that the mating roller 4 as well as the mating roller 3 (not shown here) is supported by a suitable shaft 11 mounted on a bracket 13 with hinge devices 12 at one end. to turn the matching rollers. The casting cylinder 5 is likewise supported by a shaft 14 mounted on a bracket 15. An adjustable adjusting bolt 16 is arranged in connection with the bracket 13 and contacts the support 14 of the casting cylinder 5. The adjusting bolt 16 is threaded and can be rotated by a hexagon socket 17 of matching rollers 3 (not shown). 2) and 4 to adjust the distance and the lamination compression between the casting cylinder 5. The purpose of this pressure adjustment is to prevent damage to the profile parts of the sealing strip parts 1 and 2 as a result of crushing when this strip is laminated to a melt thermoplastic film 7. At the opposite end of the shaft 11 there is another support 13-like support and pivot means (not shown). and a second support such as a bracket 15 at the opposite end of the shaft. These elements can be used to adjust the distance between the mating rollers 3 and 4 and to avoid damaging the pr of strips 1 and 2.

Figure 3 shows sealing strip parts 2 and 1 with a male profile element 45 and a female profile element 46 in a locked state. This figure also shows the outer edge portions 18 and 19 and the inner edge portions 20 and 21 of the closure strip portions 2 and 1 to be laminated to the film 7. The inner edge portions 20 and 21 may be considerably shorter than the outer edge portions 18 and 19.

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Figure 4 shows the best way to practice the present invention. A feed rack (not shown) feeds two pairs of self-locking closure strips from the roll 25. This rack applies limited backward tension to the strips, which are released from their latch and pulled toward the casting station by the press rollers 26 and 27. These press rollers adjust the tension of the opened sealing strip portions 47, 48 and 49 which pass through the respective rubber coated mating rollers 3, 4 and 28. Before the sealing strip sections 47 and 48 pass between the press rollers 26 and 27, the sealing strips 180 'are rotated in this embodiment. the profiles are directed away from the casting cylinder 5. Matching rollers 3 and 4 are provided with sealing strip portions 47 and 48 having male elements, and matching rollers 28 are fed with sealing strip portion 49 having two combined female elements. The slit casting nozzle 6 forms a film 7 which is cast on the casting cylinder 5. The matching rollers are preferably used as a result of contact with the closure strip parts pulled by the rotated casting cylinder 5, the cooling roll 29 and the compression rollers 33 and 34. The matching rollers may optionally be drawn.

The appropriate lamination between the sealing strip parts and the molten thermoplastic film depends on the lamination pressure applied by the mating rollers to the sealing strip parts, which in turn are in contact with the molten film on the surface of the casting cylinder. The lamination pressure can be adjusted using adjusting bolts or air cylinders. The use of air cylinders is recommended due to their self-compensating properties in adjusting the lamination pressure in the event that the mating rollers and / or the casting cylinder deviate slightly from the round. Each air cylinder unit usually consists of a pneumatic piston or cylinder actuator with a rod fork connected to the element to transfer the pressure caused by the air cylinder to this element. The magnitude of the applied pressure can generally be adjusted by means of a pressure control device.

In a preferred embodiment of the invention, the aforementioned lamination pressure is provided by air cylinder units that produce a lamination force between about 50 lb (22.5 kg) and 500 lb (226 kg) applied to a width of about 3 in (7.6 cm) of matching rollers. , or between about 17 lb (7.5 kg) ... about 170 lb (77 kg) per one inch (2.54 cm) width of the alignment rollers. In use, it is preferred to use a force of about 200 lb (90.7 kg) applied to the approximately 3 in (7.6 cm) width of the fitting rolls to laminate the sealing strip portions to the molded thermoplastic film.

The knives not shown can be placed between the matching rollers to push the molten thermoplastic film closer to the casting cylinder and thus to transfer heat more efficiently to this casting cylinder. Additional air nozzles (not shown) can be used to facilitate cooling of thicker edge flanges. The laminated connecting structure, in which the shutter profiles are directed downwards, passes over the cooling roller 29 to provide additional cooling.

After passing over the cooling roll 29, the edges of the laminated assembly are smoothed with knives 30 and 31 which cut the cast excess film, e.g. the edge ribs 32, from the laminated combination. The cut web is kept under constant tension by causing the web to pass between the press rollers 33 and 34. The leveling is preferably carried out just before the press rollers 33 and 34 due to the relatively high tension of the film, which allows a permanent leveling. The central cutter 35 cuts and separates the laminated assembly between the two female profile elements. The separated laminated assemblies and edge smoothing strips may be moved over non-shown curved rollers to smooth soft wrinkles before the assemblies pass through folding stations 50 with grooves into which the profile elements of the laminated assemblies fit. The cut-off edges 32 are caused to deviate from the waste winding devices (not shown) and thus bypass the folds. After folding, the profile elements of the laminated assemblies are trapped by the action of air-supported guide surfaces 36 and 36 'which orient the locking profile elements before the paired rollers 37, 38 and 37', 38 'close them. The compression rollers 39, 40 and 39 ', 40', which have grooves in the regions of the closed sealing strip portions, keep the web tension constant during the critical folding and sealing steps. The two continuous webs of resealable container blanks are each wound on separate rollers 41 and 42 mounted on separate winding devices (not shown).

Fig. 5 is a side view of a mating roller 4 supported by a suitable shaft 51 fitted to a support 52 having a pivot device 53. A portion 54 spaced from the center of the support 52 is shown connected to a rod fork 55 extending from a pneumatic piston from an air cylinder unit 57 or 56. The pressure from the air-cylinder unit 57 can be adjusted by means of a pressure regulator (not shown) in the air line. In use, the air cylinder unit 57 pushes the cylinder actuator 56 and rod fork 55 toward a portion 54 spaced from the center of the bracket 52 provided with the pivot device 53, the bracket 52 pivoting to the casting cylinder 5 to provide lamination pressure -plastic between the film.

Various alternatives may also be used in the practice of the invention. Thus, closure tape portions can be made that are not caused to lock into the corresponding closure tape portion. These non-locking tape portions can be used in the aforementioned step of requiring the locked closure tape to be wound from a roll stock. Furthermore, each sealing strip part can be injection molded directly into the lamination area using suitable cooling means. In addition, the laminable surface ‘1 83493’ of the edges of the sealing strip and / or the thermoplastic film may be coated with another polymer or injection molded together with such a different polymer to promote lamination. The laminating surface of the edges of the sealing strip can be preheated to facilitate lamination with the film. Multiple lamination systems can be used. The casting cylinder may have a slightly roughened or textured surface to provide the desired properties of the container body and side area. A profile can be made in the slit nozzle to produce a thicker film in the lamination area. Such profiling can improve the quality of the container, especially to provide reliable use of the container in the cold, and also improve the perceptible quality by stiffening the upper end of the container. If desired, each closure profile, each closure edge, and thermoplastic film can be made of completely different polymers to provide unique container constructions, such as forming a flexible closure in a strong, rigid container body. Different colors can also be given to the tank body and different parts of the sealing strip. Alternatively, instead of winding the container blanks on a roll, the blanks may be fed directly to a container forming / cutting-closing mechanism, such as a bag making machine.

It should be noted that some advantages over the prior art can be achieved by applying this invention. One of these advantages is that the tension acting on the sealing strip parts when feeding the strip parts from the feed source to the lamination area is adjusted so as to obtain a more even lamination with the thermoplastic film. Another advantage is that because the closure strip portions are fed to grooved mating rollers that position and orient the strip portions, and because the width of these rollers is only equal to the portion of the closure strip to be laminated, the mating rolls never come into contact with this molten thermoplastic film. As previously shown, the mating roller t is prevented from coming into contact with the molten thermoplastic film by means of adjusting bolts placed between one or more mating rollers and the casting cylinder i2 83493. In the application of the invention, only a short inner edge is required in each part of the sealing strip, since the film is attached to the sealing strip over most of the back surface of the edge of this sealing strip.

The connection of the continuous film to the sealing strips is also not limited to speeds of about 30 m / min, but much higher speeds and at the same time excellent lamination quality can be achieved. Because the lamination area covers most of the back surface of the sealing strip portions, the laminations are much less noticeable and the possibility of welding both sealing strip portions together in the film tensioning area has been eliminated, as can occur when hot sealing the film to the sealing sealing strips. Finally, since there are fewer critical control situations compared to a hot air sealing system, more uniform results are achieved thanks to the present invention.

The precise details of the structure shown and described above do not limit the invention, as one skilled in the art will obviously be able to make various modifications based on the foregoing description without departing from the principles of the invention.

Claims (18)

A method for producing a plastic film fused to interlocking closure strip portions, wherein the strip portions have profile and edge portions, characterized in that as method steps the sealing strip portions (1, 2; 47, 48, 49) are fed and advanced to a single rotatable mating roller (43). circumferential grooves near opposite ends of the roll and a recessed area (44) between the grooves, or for a plurality of rotatable, spaced-apart, circumferentially grooved mating rollers (3, 4; 3, 4, 28) so that the non-locking profile molding portions of the closure strip portions extend or in the grooves of rollers; adjusting the tension of the sealing strip portions when the sealing strip portions are fed to the mating roller or rollers; injection molding the molten plastic film (7) onto a rotatable casting cylinder (5) located opposite the mating roll or rollers so that the plastic film merges with the edges of the sealing strip portions while adjusting the lamination press applied to the molding rolls by the molding roll or rollers; and then cooling the laminated combination of plastic film and sealing tape portions. Method according to Claim 1, characterized in that the compression is adjusted by at least one air cylinder (57) connected to the supports (13, 52) supported by the matching roller or rollers. Method according to one of the preceding claims, characterized in that the self-compensating pressure caused by the air cylinder (57) is transferred from the articulation point of the support (52) to a separate part (54) by means of a rod fork (55) and a pneumatic piston or other actuator (56). Method according to one of the preceding claims, characterized in that the magnitude of the pressure caused by the air cylinder (57) is controlled by a pressure control device. Method according to any one of the preceding claims, characterized in that the lamination force is about 50 lb (22.5 kg) to 500 lb (226 kg) applied to a width of about 3 inches (7.6 cm) of fitting castings, or between about 17 lb (7.5 kg) to 170 lb (77 kg) aligned per one inch (2.54 cm) width of the alignment roller. A method according to claim 5, characterized in that the lamination force is about 200 lb (90.7 kg) applied to an approximately 3 inch (7.6 cm) width of the matching roll. 7. Apparatus for making a plastic film embedded with interlocking closure strip portions having profile portions and edge portions, the apparatus having feed means for feeding the sealing strip portions (1/2; 47, 48, 49); rotatable casting cylinder (5); injection molding means (6) for molding the molten plastic film (7) onto the casting cylinder (5) so that the molten plastic film (7) merges with the edge portions of the sealing strip parts (1, 2; 47, 48, 49); and cooling means for cooling the diluted combination of plastic film and sealing strip parts, characterized in that the device has counter-rotating, circumferentially spaced circumferential grooving rollers (3, 4, 28) or one opposite the casting cylinder (5), opposite the casting cylinder (5), a mating roll (43) having circumferential grooves near opposite ends of the roll and a recessed area (44) between the grooves, the mating roller (s) being adapted to receive the profile parts of the sealing strip parts (1, 2; 47, 48, 49), the casting cylinder ( 5) the shaft being parallel to the shaft or shafts of the matching roller (43) or rollers (3, 4, 28); advancing means for advancing the closure strip portions (1, 2; 47, 48, 49) on the matching roller (43) or rollers (3, 4, 28); means (26, 27) for adjusting the tension of the closure strip portions when the sealing strip portions are fed to the mating roller (s); and at least one means (57) adapted to control the lamination compression, the matching roller (43) or rollers (3, 4, 28) of which apply to the casting cylinder (5) when the sealing strip parts (1, 2; 47, 48, 49) fusing the plastic to the film. Device according to Claim 7, characterized in that the mating rollers are a plurality of rubber-coated rollers (3, 4; 3, 4, 28). Device according to Claim 8, characterized in that the width of the mating rollers (3, 4, 28) is equal to the width of the sealing strip parts (1, 2; 47, 48, 49), and in that the mating rollers (3, 4, 28) are preferably axially movably mounted on a common shaft (11). Device according to Claim 8 or 9, characterized in that the matching rollers (3, 4, 28) are arranged on different shafts. Device according to one of the preceding claims, characterized in that the supports (13, 52) of the matching rollers (43; 3, 4, 28) have pivoting means (12, 53). Device according to one of the preceding claims, characterized in that the means for adjusting the lamination pressure are at least one air cylinder (57). Device according to claim 12, characterized in that the air cylinder unit (57) is connected via a pneumatic piston or actuator (56) and a rod fork (55) to a part (54) separate from the center of the pivot rod (52) to provide lamination pressure. Device according to one of the preceding claims, characterized in that the lamination force is from 50 lb (22.5 kg) to 500 lb (226 kg) applied to the width of the fitting rolls of about 3 to 83493 inches (7.6 cm), or between about 17 Ib (7.5 kg) ... 170 Ib (77 kg) aligned to one inch (2.54 cm) wide of the alignment roller. Device according to claim 14, characterized in that the lamination force is about 200 lb (90.7 kg) applied to a width of approximately 3 inches (7.6 cm) of the matching roller. Device according to Claim 13, 14 or 15, characterized in that there is a pressure control device in the air duct for regulating the pressure coming from the air cylinder unit (57). A laminated article for use in the manufacture of bag products having a lockable closure, the laminated article comprising a plastic film (7) embedded in lockable closure tape portions (1, 2; 47, 48, 49) having profile portions and edges. , characterized in that the closure strip portions (1, 2; 47, 48, 49) are arranged to advance on a single rotatable matching roller (43) having circumferential grooves near opposite ends of the roller and a recessed area (44) between the grooves, or on a plurality of rotatable spacers spaced apart. a circumferentially grooved mating roll (3, 4; 3, 4, 28) such that the non-interlocking profile portions of the closure strip portions extend into the grooves of the mating roll or rollers; the tension of the closure strip portions is adjusted when the closure strip portions are fed to the matching roller or rollers; the molten plastic film (7) is fed to a rotatable casting cylinder (5) opposite the matching roller or rollers so that the plastic film is fused to the edges of the sealing strip parts, the lamination press being applied to the adjusted by means of a self-compensating air cylinder (57); and then the laminated combination of plastic film and sealing tape portions is cooled. it 83493 Laminated product according to Claim 17, characterized in that the edge smoothing parts (32) are cut and removed from the plastic film (7) and the sealing strip parts (1, 2; 47, 48, 49). Laminated product according to Claim 17 or 18, characterized in that it is cut and closed to form a container. 18 83493