MXPA00002179A - High compression zipper - Google Patents

Abstract

A zipper strip (10) for a reclosable package having a transverse zipper is provided. The zipper strip (10) comprises a male profile (12) and a female profile (14). Each profile (12,14) includes at least one interlocking member (18,20,24,26) extending from a base (16,22) towards the opposite profile interlockable with an interlocking member on the opposite profile. One or both of the profiles is provided with at least one high compression member (28,30,32) which allows the interlocking profiles to be sealed to thermoplastic film across the widths of their respective bases (16,22) without the interlocking members (18,20,24,26) being crushed or distorted.

Description

CLOSURE OF HIGH COMPRESSION ZIPPER CROSS REFERENCE TO RELATED APPLICATIONS The present application is a partial continuation of the United States patent application serial number 09 / 114,618, filed July 13, 1998, the disclosure of which is incorporated herein. by reference. BACKGROUND OF THE INVENTION FIELD OF THE INVENTION The present invention relates to bags and plastic package with closure, of the type in which food is packaged, such as snacks, cereals and other items, to be offered for sale to the consumer. More particularly, the present invention relates to a zipper fastener strip for use in plastic bags with transverse zippers made in forming-filling-sealing machines (FLS). DESCRIPTION OF THE PRIOR ART The present invention relates to improvements in the packaging manufacturing technique, and can be practiced in the manufacture of bags and packages of the type that can be used for various products for the consumer, but which are particularly useful for foods that they must be stored in airtight and moisture-tight packages and leak-free until they are initially opened to access the contents of the product, and they can then be closed by a zipper to protect the remaining product inside. The prior art is already well developed, but nevertheless remains susceptible to improvements that contribute to greater efficiency and effectiveness with respect to cost. In particular, the present invention relates to the packing field with closure known as a transverse rack. By making a bag having a transverse zipper, the zipper is joined transversely to the longitudinal axis of the material used to make the bag, as opposed to being joined to the material parallel to the longitudinal axis. In the U.S. patent No. 4,909,017 discloses a method and device for manufacturing plastic bags with transverse slide fastener in an FLS machine. Before inserting the transverse seal to the closing packaging field, the plastic bags. with closures made in FLS machines are typically made with a continuous longitudinal zipper, i.e., a zipper parallel to the longitudinal axis of the thermoplastic film used to make the bags. However, there are two primary problems with the longitudinal zipper technique. First of all, there is a problem to obtain a satisfactory seal of the bags so that there are no leaks, since the crossbars, or Side, sealing machine FLS should flatten and seal the zipper while sealing the thermoplastic film from which the packages are made. The difficulty with which this seal is consistently and effectively achieved is reflected by the high occurrence of leakage in the packages. Second, the length of the closing bags that are made in FLS machines when the closure is joined parallel to the longitudinal axis of the thermoplastic film is limited to the diameter of the filling tube of the FLS machine. Therefore, in general, bags of this type are wider than long. Although such bags are suitable for certain products where shorter bags, such as cheese or chicken pieces, are desirable, these bags are not suitable for applications where longer bags, such as potato chips and other snack foods, are desirable. One of the approaches to solve these problems was to replace the transverse zippers with longitudinal zippers. When a transverse rack is provided, the transverse seal bars associated with the FLS machine do not flatten the rack during formation of the upper and lower pack seals, since the transverse sealing bars can seal the rack to the thermoplastic film transversely, no need to flatten the ends of the zipper. Furthermore, when a transverse rack is used, the length of the packages manufactured in the FLS machine can be varied, while the width of the slide fastener remains the same. The present invention relates to a particular type of zipper strip that can be used in transverse zipper applications, a method of attaching the zipper strip to thermoplastic films, a method for manufacturing closure packages in an FLS machine using thermoplastic film equipped with zipper strip, and a zipper package that uses the zipper strip. In the typical applications for manufacturing packages with transversal rack, zipper strips with flanges are used. The zipper strips are sealed to the thermoplastic film by the ridges, thereby preventing damage to the interlocking closure elements that might otherwise occur during sealing. However, the use of flanged racks was shown to be problematic in the sense that the ridges tend to detach or delaminate from the thermoplastic film due to peeling forces which are transmitted to the flanges when the user opens the bag. Although the techniques are well known in the art, zippers are flange, these closures are unsuitable for transverse zipper applications, as they are too narrow to ensure proper sealing by unspecified sealing bars, and because sealing these zippers to thermoplastic films causes damage and distortion in interlocking fasteners . It is therefore an object of the present invention to provide a zipper strip without rims for use in plastic bags with a transverse slide fastener, which solutions the sealing problems described above. Another object of the present invention is to provide a method for joining the stripless zipper strip to thermoplastic films, where these films can be subsequently used in an FLS machine for making closure packages. Another object of the present invention is to provide a method for manufacturing packages from the thermoplastic film equipped with a fringe strip without a rim. Still another object of the present invention is to provide a package utilizing the non-flanged zipper strip. SUMMARY OF THE INVENTION According to the foregoing, the present invention is, in four aspects, a zipper strip for use in bags with transverse closures; a method to join the zipper strip to a continuous supply of thermoplastic film; a method for manufacturing zippered bags in an FLS machine using the thermoplastic film equipped with a zipper strip; and a zippered bag that uses the zipper stripe. According to the first aspect of the present invention, the zipper strip comprises a male profile and a female profile. The male profile includes a base and at least one male interlacing member extending from the base to the female profile. Similarly, the female profile includes a base and at least one female interlacing member extending from the base to the male profile, where the male and female interlacing members can be joined together to join the male and female profiles to one another . None of the profiles has ridges, and they are wide enough to ensure that the sealing bars make a precise seal. One or both profiles further include at least one high compression member that can be attached to a portion of the other profile, which allows both profiles to be sealed to the thermoplastic film over the widths of their respective bases, without the male and female interlacing members. female are crushed or distorted by the application of heat and pressure directly behind or adjacent to the interlacing members by the sealing bars. The problem of peeling associated with the zipper with flange is eliminated, since both profiles can be completely sealed to the thermoplastic film on the widths of their respective bases. In the second aspect of the present invention, thermoplastic film is intermittently fed from a continuous supply, and fed to the FLS machine. A section of a zipper strip interlaced with the flat film, transversely to its longitudinal axis, is joined as it advances in increments of the length of a bag when initially sealing, or sticking, one of the profiles of the film. The film equipped with a zipper can be rolled up and then used in an FLS machine, or it can be fed directly to the FLS machine to make bags with zippers. In the third aspect of the present invention, the thermoplastic film is fed with transverse zipper strips attached at intervals of the length of the bag to an FLS machine, where the film is formed in a bag, filled and sealed. Specifically, the thermoplastic film equipped with a transverse rack is bent over the collar of the FLS machine and wrapped around the filler tube to form a tube. The longitudinal edges of the film are then sealed to form a reverse union. The transversal sealing presses then seal the lower part of the tube to form an open bag. If desired, the bag is then filled. Finally, the transversal sealing presses seal both profiles with opposite walls of the bag over the widths of their respective bases, without sealing the profiles with each other, and sealing the upper part of the bag to make a finished bag. According to the fourth aspect of the present invention, the finished bag can be opened by pulling it out on the walls of the bag. Now the present invention will be described with more complete details, making frequent references to the figures that are identified below. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a cross-sectional view of a zipper strip, according to a first embodiment of the present invention. Figures 2 (a) - (g) are cross-sectional views of rack strips in accordance with alternative embodiments of the present invention. Figure 3 is a perspective view of the zipper strip of Figure 1 being attached to the thermoplastic film according to the present invention. Figure 4 is a perspective view of an FLS machine making closure bags from thermoplastic film, according to the present invention.

Figure 5 is a cross-sectional view of a completed bag in accordance with the present invention. DETAILED DESCRIPTION OF THE PREFERRED MODALITY With specific reference to the previously identified Figures, Figure 1 is a cross-sectional view of a zipper strip 10 in accordance with the first aspect of the present invention. The zipper strip 10 comprises a male profile 12 and a female profile 1. The male profile 12 includes a base 16 and male first and second interweaving members 18 and 20 extending from the base 16 towards the female profile 14. The first and second male 18 interweaving members 20 and 20 each have an asymmetric arrow shape, so that it is easier to open the zipper strip 10 from one side than from the other. In the case of bags for potato chips and the like, the male interlacing members will be adapted so that the bag is easier to open from the side of the contents of the bag, since typically these bags are opened from the side of the contents. The female profile 14 includes a base 22 and first and second female intermeshing members 24 and 26 that extend from the base 22 towards the male profile 12. The first and second female intermeshing members 24 and 26 are each comprised of two members that are they curve inward and that they form a receptacle or channel in which they can joining, respectively, the first and second male 18 and 20 interweaving members. It should be noted that although the configuration described above for the male and female interlacing members is preferred, any configuration providing interlacing may be used. In addition, any number of male and female interlacing members can be used. The male and female profiles 12 and 14 are extruded from a plastic material that is commonly used in the packaging industry, such as polyethylene. In addition, the profiles can be provided with a sealer in their bases to assist in the sealing of the profiles to the thermoplastic film used to make the bags. The male profile 12 further includes wedge-shaped high compression members 28 at both ends of its base 16, and a central high compression member 30 between the first and second male 18 and 20 interlacing members, where they all extend from the base of the male profile 16 towards the female profile 14. The high compression members 28 and 30 are longer than the first and second male 18 and 20 interweaving members. The female profile 14 includes wedge-shaped high compression members 32 to both ends of its base 22, which come into contact with high members wedge-shaped compression 28 on the male profile when the profiles are intertwined and pushed together. The high compression members work in the following way. When one or both male and female interlocking profiles 12 and 14 are sealed to the thermoplastic film, such as by sealing bars, the profiles are compressed with one another. This compression causes the opposed wedge-shaped high compression members 28 and 32 on the male and female profiles 12 and 14 to come into contact with each other, and the central high-compression member 30 of the male profile comes into contact with an internal surface 34 of the base of the female profile. The lengths of the high compression members are such that these contacts occur before the limbs 36 and 37 of the male interlacing members 18 and 20 come into contact with the female profile 14, or that the ends 38 and 39 of the interlacing members female 24 and 26 come in contact with the male profile 12, thereby damaging or distorting the interlacing members. In addition, the high compression members are much thicker than the male and female interlacing members, thereby ensuring that the high compression members themselves do not distort during sealing, or are sealed with the opposite profile. In this way, high compression members they prevent the distortion and crushing of the interlacing members, and allow the profiles to be sealed to the thermoplastic film over the widths of their bases. In the absence of the high compression members, the interlacing members would be distorted or crushed by the heater bars, which would render the zipper strip unusable. Since the rack 10 is not provided with rims, the profiles must be wider than usual, in order to ensure that the sealing bars seal the profiles to the thermoplastic film. This additional width ensures that the sealing bars, which are not very precise, do not stop gluing the narrow zipper during the sealing operation. This additional width also provides the additional benefit that it is easier for the user of the bag to close the zipper strip, because of the sense of spaciousness of the zipper strip. It should be noted that the present invention is not limited to the amount and configurations of the high compression members shown in Figure 1. Any amount and any configuration of high compression members can be used to practice the present invention. In Figure 2 examples of other profiles are shown, in accordance with the present invention.

In Figure 2 (a), the male profile 40 is provided with three rectangular high compression members 42, which are longer than any of the male interlacing members. 43. In Figure 2 (b), both profiles 44 and 46 are provided with three rectangular high compression members 48, which come into contact with an opposite member of high compression in the other profile during sealing. In Figure 2 (c), male and female profiles 50 and 52 are each provided with two rectangular high compression members, one of which 54 comes into contact with the base of the opposite profile, and the other 56 comes into contact with one opposite member of high compression in the other profile during sealing. The embodiment of Figure 2 (d) is similar to that of Figure 2 (a), except that the central high compression member of the male profile 58 is replaced with a high compression member of triangular shape 60 which coincides with a high compression member of complementary shape 62 in the female profile 64 during sealing. The embodiment of Figure 2 (e) is also similar to that of Figure 2 (a), except that the high compression members 66 in the male profile 68 are triangular. The modality of Figure 2 (f) also makes use of triangular members of high compression 70 and 72, although the compression members are inverted, so that they are the bases, instead of the vertices as in Figure 2 (e), which come into contact with the base of the opposite profile.

Additionally, the male profile 74 is provided with a single central high compression member 70, while the female profile 76 is provided with a high compression member 72 at each of its ends. In the modality of Figure 2 (g), the male profile 78 is provided with a central and rectangular high compression member 80, which is longer than the male interlacing members 82, and the female profile 84 is provided with a channel 86 for receiving the high compression member 80.

Additionally, members 88 that form channel 86, if they are long enough, can also act as high compression members. Although the profiles with poles and wedges are well known in the prior art, as disclosed, for example, in U.S. Patent Nos. 4,736,451, 3,565,147, 5,509,734 and 5,558,614, the posts and wedges in these references do not act as high compression members, but act to stabilize the rack, or increase the closing characteristics. Figure 3 shows the zipper strip 10 of Figure 1 being attached to the thermoplastic film 90, according to the second aspect of the present invention. The Zipper strip is supplied from a continuous roll 92 and is pulled on the film 90 and disposed on the film by a placing device 116 (not shown in Figure 3, for clarity). The positioning device 116 may have any of a variety of shapes that are already known to those skilled in the closed-package art, such as a vacuum conveyor for pulling the zipper strip 10 over the film 90, and a razor cutting the zipper strip 10 of the continuous strip roll 92. The thermoplastic film 90 is fed from a continuous roll 94, as shown in Figure 3, in increments equal to the length of the bags that will ultimately be formed from of the 90 movie on a FLS machine. The film 90 has a longitudinal axis X which is parallel to the direction of travel of the film 90. The zipper strip 10 is disposed on the film 90 transversely to the longitudinal axis X, with the male profile 12 on top of the female profile 14, or vice versa. As disclosed in U.S. Pat. No. 4,909,017, the zipper strip 10 has a length approximately equal to half the width of the film 90, and is arranged in the central part of the film. Sealing bars 96 are placed to join the female profile 14 to the film 90 when initially sealing or gluing the female profile to the movie. The high compression members, as discussed above, prevent the sealing bars 90 from damaging or distorting the interlacing members. In the third aspect of the present invention, the film equipped with a transverse zipper is fed to the FLS machine, as shown in Figure 4. The thermoplastic film 90 is fed down, on a collar 98 and folded around a filler tube 100. The edges of the film are joined and joined by a pair of rollers 102. The edges are then welded by sealing bars 104 to form a rear longitudinal seam 106. It can then be contained by the tube 100 in the bag 108 having a lower seam 110. As will be discussed below, the lower seam 110 was made upon completion of the preceding bag. After introducing the content, the upper part of the bag is completed by the action of transverse sealing presses 112, which perform four simultaneous functions. First, the transverse sealing presses 112 finally seal the male and female profiles 12 and 14 with opposite walls of the bag over the widths of their respective bases. A commercially known sealant can be used in the bases of the profiles to facilitate the finishing of these seals, without sealing the profiles 12 and 14 with one another. The high members Compression, as discussed above, prevents interlocking members from being crushed or distorted during sealing. Second, the transverse sealing presses 112 seal the upper part of the bag to form a seal against interventions 114. Third, the transverse sealing presses 112 make the lower seam 110 for the next bag. Fourth, the transverse sealing presses 112 cut the finished bag 108 of the film 90. The finished bag 108 has a seal against interventions 114, a transverse zipper 10, a bottom seam 110 and a rear seam 106. In order to ensure that the High compression members do not seal the opposite profile during the sealing process, the ends of the high compression members can be treated, as in the case of a small ink layer. While the thickness of the high compression members would generally prevent the sealing from occurring, as discussed above, this treatment would provide additional caution, or would cover a situation where smaller profiles are used. According to the fourth aspect of the present invention, in Figure 5 a cross section of the finished bag 108 is shown. Since all the widths of the bases profiles 12 and 14 are sealed to the bag, there is no danger of that none of the profiles take off from the bag when the user opens it, as shown by the opening forces F (the snack bags, unlike other bags, are typically opened from the content side). Accordingly, the objects of the present invention are achieved in the manner described above. The modifications to the foregoing could be obvious to those skilled in the art, although the invention could not be modified to the extent that it fell outside the scope of the appended claims.

Claims (11)

1. CLAIMS 1. A zipper strip for a closure package, wherein the zipper strip comprises: a male profile and a female profile; the male profile includes a base and at least one interlacing member extending from the base towards the female profile; the female profile includes a base and at least one interlacing member extending from the base to the male profile, where at least one male interlacing member can be joined with at least one female interlacing member to join the male and female profiles to each other; at least one of the profiles further includes at least one high compression member extending from its corresponding base to the other profile, where at least one of the high compression members comes into contact with a portion of the other profile when the profiles are they intertwine and oppress one another, to prevent the limbs of the intertwining members from coming into contact with the opposite profile; where the widths of the respective bases of the profiles can be sealed to thermoplastic film by the application of heat and pressure, without damaging or distorting the male and female interlacing members.
2. 2. The zipper strip according to claim 1, wherein both profiles include at least one high compression member that can make contact with a portion of the other profile.
3. 3. The zipper strip according to claim 1, wherein the male profile includes a pair of wedge-shaped high compression members positioned at opposite ends of the base of the male profile, where each wedge-shaped high compression member. it may come into contact with a high compression member in the form of an opposite wedge in the female profile.
4. 4. The zipper strip according to claim 1, wherein at least one high compression member can be brought into contact with the base of the opposite profile.
5. 5. The zipper strip according to claim 1, wherein the male profile includes a longer high compression member than at least one of the male interlacing members.
6. 6. The zipper strip according to claim 1, wherein the female profile includes a longer high compression member than at least one of the female interlacing members.
7. 7. The zipper strip according to claim 1, wherein the end of at least one high compression member is treated to prevent the high compression member from being sealed to another profile.
8. 8. The zipper strip according to the claim 1, wherein the male profile includes two male interlacing members, wherein each of the male interlacing members can be interlocked with an opposing interlacing member in the female profile.
9. 9. The zipper strip according to claim 8, wherein the male profile includes first and second high compression members positioned at opposite ends of the male profile base, and a third high compression member positioned between the male interlacing members.
10. 10. The zipper strip according to claim 9, wherein the high compression members can come into contact with the female profile base.
11. 11. A method for joining a zipper strip transversely to a thermoplastic film, for use in the production of closure packages to be made in a forming-filling-sealing machine from the thermoplastic film, wherein the method comprises the steps of: supplying thermoplastic film having a longitudinal axis, and advancing the thermoplastic film on the shaft in amounts equal to the length of the packages; supplying a section of a zipper strip having interlocking male and female profiles; where the male profile includes a base and at least one interlacing member extending from the base to the female profile; wherein the female profile includes a base and at least one interlacing member extending from the base toward the male profile, where at least one male interlacing member can be joined with at least one female interlacing member to join the male and female profiles together; at least one of the profiles includes at least one high compression member extending from its corresponding base to the other profile, where at least one high compression member may come into contact with a portion of the other profile when the profiles are interlaced and pressed together to prevent the ends of the interlaced members from coming into contact with the opposite profile, so that the widths of the respective profiles bases can be sealed to the thermoplastic film by the application of heat and pressure, without damaging or distorting the profiles. male and female interlacing members; placing the section of the zipper stripe on the film transversely to the longitudinal axis, with one of the profiles placed on the other profile; and join the lower profile with the thermoplastic film.