Touch fasteners, their manufacture, and products incorporating them

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DESCRIPTION

Contact closures and their manufacture. Background of the invention

This invention relates generally to touch closures, such as composite touch closures having looped and interlocking closure elements extending from a portion of a common substrate, for application in products such as closure tapes for bags with automatic closing, and methods and apparatus for their manufacture. The invention also seeks to apply self-closing contact closure tapes to a sheet or film, especially to a flexible and disposable sheet or film designed for packaging, such as in fill and vertical packages and fill and horizontally. , and in the manufacture of bags.

Much progress has been made in the field of hook and loop fasteners in the last thirty years. The first contact closure products of this type consisted of two male tapes, each being woven or interwoven. One tape could include loops of filaments interlaced at one base, and the other could include filaments interlaced to form loops and then cut to form hooks. In some cases, the loose ends of the plastic filaments stretched over the molten male tape could be undone to form prominent heads. This form of closure elements is sometimes referred to as a "mushroom" to distinguish it from reentrant "hook" kinks. In some cases, similar matrices of differentiated closure elements are developed on the two parts so that they mesh with the others so as to form a releasable closure, these being known as self-engaging clasps or hooks.

More recently, the continuous molding of closure elements extending from a sheet-shaped resin base has generated less expensive and thinner male tapes. Important improvements in this area include the development of continuous molding of closure tapes that are used in fixed mold cavities (see Fischer, US Patent 4,794,028), and the ability to provide loops on the back of the male tape. closure, while forming the elements and the substrate for the closure tape (see Kennedy et al., US Patent 5,260,015), thus creating a composite closure tape capable of self-closing. Other improvements have reduced the size of closure elements moldable by such techniques, down to heights of 0.015 inches (0.38 millimeters) or less, causing very soft contact when set in dense assemblies.

Another example of a molded fastener tape involves molds that represent preformed mold tubes or similar structures incorporated with a plastic backing substrate, and thereafter represent a forming operation to convert the outer parts into a J-hook, a mushroom head or similar gear structure.

Since molded fastener tape has been refined to be more flexible and less expensive, it has found application in disposable garments such as diapers. Other improvements are desired to extend the applicability of contact closure molded products to other uses.

One such use, which will be discussed in more detail below, is that of a closure for self-sealing bags and other types of packaging.

Other types of constant-use closures for bags include, for example, the groove and rib type of closure or zip closures, such as those marketed under the name ZIPLOC. These have very different closure characteristics and stringent requirements for bonding to the sheet or film compared to the contact closure closures discussed here.

Document US 088 164 describes a bag having a first closure element and a second closure element engageable with the first closure element. The first and second closure elements are arranged on opposite walls of the bag.

EP 0 808 585 describes a method for joining an automatic closure with a backing sheet by the use of a pressure roller having raised edges.

Document US 4 955 981 describes a self closing bag having hook and loop sealing tapes arranged between a fold and a main part.

The object of the invention is to provide a method of forming a self-closing bag suitable for accepting delicate items, such as snack potatoes, without damaging the contents.

This object is fulfilled by a method having the characteristics described in claim 1. Preferred embodiments are defined in the dependent claims.

According to one aspect of the invention, a web-shaped product useful for forming bags includes a continuous sheet-shaped film and multiple extensions of the closure tape that extend transversely from side to side of the film at spaced and adhered intervals. permanently to the movie. Each extension of the closure tape includes two overlapping substrates, with each substrate separately adhered to the bag film on opposite sides of a tear zone associated with the film; a strip of loops carried over the front of the first substrate and consisting of a distinct strip of interlocking loops extending along the length of the fastener tape; and a set of loop engageable closure elements extending from the second substrate, and forming a distinct strip of closure elements extending longitudinally along the length of the closure. The first and second substrates are superimposed and adhered to the film in such a way that the loop stripes and closure elements overlap for engagement.

Preferably, the closure elements are integrally molded with resin from the front of the second substrate.

In some embodiments, the loop strip consists of a non-woven fabric of fibers preferably with a basis weight of less than about 4 ounces per square yard (136 grams per square meter).

In some embodiments, the loop tape has a width defined between two longitudinal edges thereof, fibers of the loop strip being attached to the substrate along the width of the loop tape. Preferably, fibers from the loop tape are encapsulated by substrate resin along the width of the loop tape.

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According to another aspect of the invention, a vertical self-closing bag manufacturing method and the filling method are presented. The method includes the following steps:

a) unwinding a continuous length of the film from the sheet bag and directing the unrolled film toward a forming head, the film from the bag advancing one length of bag between breaks;

b) During each pause, fix a length of the closure tape from side to side of the unrolled bag film towards the forming head, each length of the closure tape consisting of a sheet-shaped resin substrate having a front part; a strip of loops carried over the front of the substrate and forming a distinct strip of interlocking loops along the length of the fastener tape; and a set of closure elements engagable in loops and integrally molded with the front part of the substrate, and forming a distinct strip of closure elements extending longitudinally along the length of the closure tape and spatially spaced from the fringe of loops; Y

c) forming individual bags from the bag film, each bag having an associated length of the closure tape.

According to yet another aspect of the invention, there is presented a method of forming a bag or pack of foil or film for flexible and disposable packaging, having a predetermined thermoplastic composition surface. The method includes the provision of intermeshing closure tape parts, which are both separate tapes and tape parts of a common member, and joining, by welding, the reinforcement of said tape parts to the respective parts of the surface. of said plastic film or sheet. At least a first part of the fastener tape parts provides a set of differentiated fastener elements, such as hook elements, which have hook elements or curved elements in the shape of a mushroom, the fastener elements having integrally molded tubes. and extending from a thermoplastic reinforcing substrate. Another part of the tape provides a set of intermeshing elements, such as fibers or loops, or self-adhesive elements with closing elements of the first part of the tape, in such a way that the elements of the parts of the tape are able to form a releasable closure. Each part of the tape has a reinforcing surface consisting substantially of the predetermined thermoplastic composition from which the surface of the film is formed.

In some cases, during welding, the closure elements of the respective parts of the tape mesh with each other, and the reinforcements of the tape parts are simultaneously attached to the respective parts of the sheet or film by applying of energy in the respective parts of the sheet or of the film, air space provided by the intermeshing elements, which serves to prevent the unwanted welding of the parts of the tape with the others.

According to other aspects of the invention, methods are presented for applying an automatic closure on a sheet or film, which includes the steps of supplying parts of the closure tape intermeshed with each other, which are either separate tapes or tape parts of a member common and that are attached to the reinforcement from the parts of the tape to the respective parts of the surface of the sheet or film by the application of energy, such as thermal, acoustic or radio frequency energy, to produce, for example, welding or adhesive bonding. At least a first part of the fastener tape provides a set of distinct fastener elements, such as hook elements, having hook elements or curved mushroom elements, the fastener elements having integrally molded tubes extending from a thermoplastic reinforcing substrate. Another part of the tape provides a set of interlocking elements, such as fibers or loops with interlocking hooks, or self-adhesive elements with closing elements of the first part of the tape, in such a way that the differentiated elements of the parts of the tape are capable of forming a releasable closure. In one aspect, during bonding, the closure elements of the respective parts of the tape are intermeshed with each other and the reinforcements of the tape parts are simultaneously attached to the respective parts of the sheet or film, by the application of energy in the respective parts of the sheet or film, which isolates the air pockets generated in the space created by the elements meshed with each other, They serve to limit heat transfer and unwanted adhesion or welding of the closure parts to each other.

In another aspect, the cooperating parts of the releasable closure are made of materials that are incompatible or of considerably different melting temperatures, such that, under temperature conditions that allow bonding, the intermeshing elements do not tend to adhere to each other. . Arrangements of this type can avoid the need for an escapement sheet during the bonding action.

In one example, the loops and fibers of the second part of the tape are wrapped and protected by the thermoplastic resin of the reinforcement of the respective part of the closure tape, the loops and fibers being composed, for example, of resin resin. polyester, which is incompatible or has a higher melting temperature than the polyolefin resin for example, of the respective reinforcing substrate, and of the components of the first part of the opposite tape; such that, under bonding conditions, the difference in material of the loops or fibers serves to prevent detrimental change in the loops or fibers, or detrimental adhesion or welding of the loops or fibers to the first part of the fastener tape, preferably the mass of the hook elements of the first part being substantially greater than that of the loop elements, the thermal mass of the hook elements being sufficient to prevent excessive distortion of the hooks during the joining action.

In some cases, the method of the invention is advantageously carried out during stuffing packaging and vertically. In other cases, the method is advantageously carried out during stuffing packaging and horizontally. The method is also used to progress during bag making.

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In such cases, it should be noted that the invention does not require the use of any special resin for the various components, which allows the use of reinforcing substrates, such as polypropylene, polyester and nylon, for desired barrier qualities than polyethylene. no proportional.

Also, in desired cases, a wide range of compatibility layers could be employed. For example, to bond a polyester backing from a fastener tape to a polyester sheet or film, a layer can be used at a lower melt point over any component that adheres to the others. In another case, when the sheet is a smooth or covered paper, any solder layer could be introduced on one of the coupled surfaces, or the substance of the reinforcing substrate itself could be used as the solder surface, when the reinforcement is, for example, polyethylene. .

Preferably, the series of hook-engageable elements comprises a non-woven network of fibers.

In some cases, the reinforcing substrates of said tape portions overlap and are welded to respective edges of said plastic film or sheet.

The longitudinal edges of the plastic film or sheet meet in some embodiments to form a fin seal with tape portions arranged on the fin seal.

Preferably, the closure is a continuous, thin, tape-like extrusion of plastic material on one side of which the closure elements are integrally molded from material from the extrusion or bonded to the extrusion, while the extrusion is in a softened state, such that the closure elements are attached directly to the extrudate, or are formed out of the extrudate, without separate adhesives or soldering agents.

In a preferred bag construction, the bag material that forms the rear of the bag is permanently adhered to the rear surface of the closure along one of the edges of the closure, and the bag material that forms the closure The front of the bag is permanently adhered to the front surface of the closure along its opposite edge, at an edge that adheres to an area free of closure elements.

As a constant-use closure, the product provides a ventilated seal that is easy to align. Since the bands of the loops and closure elements are relatively wide, precise alignment is not necessary to form a reliable closure. The closure is able to contain a fair amount of dirt or debris while still fulfilling its closure function, making this function especially applicable when a closure for bags contains granular substances or dust. In addition, the natural porosity of the closure can provide some degree of airborne dust filtration. A ventilated closure of these characteristics can be especially convenient in aircraft cargo containers in order to adapt to pressure changes, and, due to its ventilation action, could help prevent the appearance of humidity to keep products and other products fresh. items of this type. The groove and rib break the molded tape within the center of the closure tape, which in some cases advantageously maintains an airtight seal until the bag is initially opened. The continuous closure tape is easily adaptable to standard bag making equipment and, in many cases, can be welded directly to compatible bag materials. These advantages are given to bags produced according to the invention, which have a continuous use closure.

By employing a very lightweight material with non-interlocking loops and integrally molded closure elements repeatedly, the resulting product is relatively inexpensive and flexible.

Other features and advantages will be apparent from the following detailed description and accompanying drawings, and from the disclosures of the applications of our earlier US patent and from the claims.

Brief description of the drawings

Figure 1 is a perspective view of a composite touch fastener in the form of a fastener tape.

Figure 1A is an elongated view of zone 1A in Figure 1.

Figure 2 is a cross-sectional view of the closure tape, folded and installed at the opening of the bag in a sealed condition.

Figures 3A and 3B illustrate a bag with the closure tape of Figure 1, in a sealed and open condition, respectively.

Figure 4 illustrates a first method and apparatus for forming composite touch fastener tapes, such as the fastener tapes of Figure 1.

Figure 5 illustrates a second apparatus for making stuffing bags upright, configured to contain the closure tape.

Figure 5A is an elongated view of the means for attaching the closure tape to the fabric of the bag in Figure 5, with parts cut away to show the configuration of the insulating bar and hermetic clamps.

Figure 6 is a cross-sectional view, taken along line 6-6 in Figure 5.

Figure 6A is a cross-sectional view, corresponding to Figure 6, with an inverted closure tape arrangement.

Figure 7 shows a first apparatus and method of filling packing in an inverted horizontal form, with the closure tape inserted into the flat weld between the edges of the fabric.

Figure 7A is a cross-sectional view, taken along line 7A-7A of Figure 7.

Figure 8 shows a second fill packing configuration in an inverted horizontal fashion, with the closure tape wrapped around the edges of the fabric.

Figure 8A is a cross-sectional view, taken along line 8A-8A of Figure 8.

Figure 9 shows a third filler packaging method horizontally, with the flat weld formed on the bottom of the packages.

Figure 10 shows an apparatus and method for forming bags in order to fill them from an open end opposite their closures.

Figure 11 is a cross-sectional view, taken along line 11-11 of Figure 10.

Figure 12 is an elongated view of zone 12 in Figure 10, showing the configuration of the closure when applied to tissue.

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Figure 13 shows a configuration of an edge seal formed between two adjacent bags in the method of Figure 10, in order to form exposed tear tapes.

Figure 14 illustrates the opening of a bag with an exposed tear-off closure tape, as formed from the edge seal configuration of Figure 13.

Figure 15 shows another method of forming bags, in which the closure tape is adhered to the edges of a sheet of bag film when the film is melted.

Figure 16 illustrates the manufacture of self-sealing bags from two parallel plastic fabrics and a closure tape.

Figure 16A shows a bag made by the method of Figure 16.

Figure 17 is a cross section through a bag having a closure tape with interlocking loop elements extending from an outer surface of the bag.

Figure 18 is a cross-sectional view through the closure end of a bag with an inverted closure.

Figure 19 illustrates a method and device for attaching the closure tape to the bag of Figure 18.

Figures 20A-20C show torn bag films with previously applied closures, in different configurations.

Figure 21 is a perspective view of a self-closing bag.

Figure 22 illustrates the bag of Figure 21 being open after squeezing and tearing off it.

Figure 23A is a cross-sectional view of the closing edge of the bag, taken along line 23A-23A in Figure 21.

Figure 23B shows the cross section of the bag of Figure 23A with the bag initially opened and then folded around the opening to engage the closure elements of the closure.

Figure 24 illustrates a third apparatus and method for making fill bags upright, in which the closure tape is applied to the film in the bag before the film is wrapped around the forming head.

Figure 25A is a cross-sectional view, taken along line 25A-25A in Figure 24.

Figure 25B is taken from the same perspective as Figure 25A, but with a different closure tape configuration.

Figures 26A and 26B show fastener tapes with tear seals.

Figure 27 shows hook-to-hook engagement between liner stripes of diametrically opposite hook-shaped closure elements.

Figure 28 is a cross-sectional view, taken along line 28-28 in Figure 27. Description of embodiments

Referring to Figure 1, a continuous and longitudinal closure tape 100, to seal for example a bag, consists of a resin substrate 102 in the form of a thin sheet, with parallel, continuous and longitudinal stripes 104 and 106 of loops and elements. closure, respectively, on its front part 108. Stripes 104 and 106 are evenly spaced from the center "C" of the fastener tape, such that when the tape is longitudinally folded at the "C" to cover the front 108, the fastener elements of stripe 106 the loops of strip 104 engage and retain to form a releasable closure. The closure elements 110 of the strip 106 are integrally molded and extend from the front 108. In this embodiment, these closure elements are in the form of J-hooks that extend, in series, along the length of the closure tape. Some of the J-hooks point in the opposite direction along the tape. Other shapes of closure elements could also be employed, including those that protrude above the substrate 102 across the width. A suitable form of closure element is the CFM29 hook form (approximately 0.015 inches or 0.38 mm in height), available in various products marketed by Velcro USA in Manchester, New Hampshire.

The loop band 104 consists of a preformed non-woven fabric of polymer fibers, which may include a stabilizing binder, and which are adhered to the front 108 of the substrate 102 at different points from side to side of the width and extent of the tissue. Suitable loop materials include those described in US patent application 08 / 922,292, and in related PCT patent application PCT / US98 / 18401.

Preferably, the non-entangled loop material in stripe 104 is very thin, eg, less than about 0.040 inches or 1 mm thick (more preferably, less than about 0.020 inches or 0.5 mm thick), with fibers of tissue maintained in a transversely extended condition, and loose loop structures extending from its exposed surface. As discussed in the aforementioned patent applications, the loop structures extend from the associated knots in the spread fabric, which could be stabilized by the liquid binder contained in the knots and polymerized. Between the knots, the tangle of thin fibers is not very dense and is transparent enough to allow images to be easily seen between them. Generally speaking, the loop material has a basis weight (in its preformed state, including any previously applied binder) of less than about 4 ounces per square yard (136 grams per square meter), preferably less than about 2 ounces per square yard. (68 grams per square meter). Other details of this loop material could be found in the applications mentioned above. For applications where the substrate resin partially penetrates the loop material when the substrate is formed (as will be discussed below), the perforated loop material preferably only extends in the transverse direction by only about 22% to leave an amount fair tracing and avoid total penetration.

On some occasions, the loop material 104 is partially directly wrapped in substrate resin when the substrate is formed in a continuous molding method (described below). In other cases, it is adhered to the formed substrate, by ultrasonic bonding, welding or adhesives.

For some applications, some lightweight meshes are also suitable materials. Examples of such meshes are Guilford Knits products 19902 in

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Greenville, South Carolina, which are made of polyester fibers and have a basis weight of only about 1.8 ounces per square yard (54 grams per square meter). For a heavier mesh, we prefer Guilford's 19029 product, a nylon mesh of about 3.3 ounces per square yard (112 grams per square meter). Lightweight mesh products are also available from TYBOR, Spain, and MIZARD, Italy.

As an alternative to introducing a sheet of preformed loop material into a forming nip to create the loop stripe 104 of the fastener tape, the meshed loops could be formed after the formation of the base of the tape. close by sewing the loops directly into the base (as in a MALAMO method), or by tying a ribbon of loop material on the part of the closure strap.

Referring again to Figure 1, molded into the front 108 of the substrate 102 along its center, there is a mound-shaped longitudinal rib 132 between a pair of grooves 134 molded into the front 108. An example of this rib 132 has a height of approximately 1/32 inch (0.6 millimeters) and a width of approximately 1/92 inch (0.8 millimeters) at its base. The rib could have a mound-shaped contour, as shown, or a rectangular cross-section with parallel sides. Preferably, the rib is longitudinally continuous, as shown, but another possibility is that it could be formed in a series with appropriate shapes of protrusions. At least one of the uniform zones 135 between the grooves 134 and the loop and hook stripes 104 and 106 in Figure 1 contains, in some cases, a layer of adhesive, such as pressure sensitive adhesive (not shown), to provide a self-closing seal in applications where a releasable opening is desired. In these examples, surfaces 135 provide an airtight, non-vented seal when the bag is closed, and complement the mechanical closing force of hook and loop closures. Preferably, an adhesive is used that has been compounded to stick primarily to itself or to the opposite part of the substrate, so that it does not pick up excessive debris from the contents of the bag. In other non-illustrated embodiments, the grooves 134 or the rib 132, or both, are formed in the rear of the substrate, adjacent to the closure elements and the loop material.

The formed closure tape 100 is permanently installed at the opening end of a bag, attaching the edge areas 136 of the closure tape to the outer edges of the bag upon opening, with the loop and hook stripes facing each other. front, as shown in Figure 2. The bag could be attached, as shown, to the rear of the closure tape, in which case the edge areas 136 are delimited at the rear of the closure tape, or at the front, with the edges of the bag inside. Methods for attaching the closure tape to the bag include, but are not limited to, welding, adhesive, bonding, or sewing. A preferred method of attaching a closure tape to a bag of a compatible resin is direct welding of the resin on the closure substrate to the resin in the bag, as will be discussed below. In this way, the polyethylene closure tapes could be easily welded to the polyethylene bags.

Figure 3A illustrates a sealed bag 138 having a polyethylene frame 140 welded to the closure tape 100 from side to side at its opening end. Preferably, the thickness of the substrate of the closure tape is substantially the same as the thickness of the material of the bag structure, in the range of 0.002 to 0.005 inches (0.05 to 0.13 millimeters). However, substrates up to at least 0.015 inches (0.36 millimeters) thick could be produced by the methods described below. To initially break the seal and open the bag, the outer fold of the closure tape 100 is grasped and torn, thus breaking the folded edge from one end of the bag to the other, as shown in Figure 3B. By grasping the outer fold of the fastener tape, the middle rib 132 between the thumb and forefinger is grasped. Thus, rib 132 provides a thicker edge for easy gripping. As the folded edge of the fastener tape is torn off, the fastener tape breaks along the slots 134. The grooves 134 serve as break points to initially open the associated bag, and could be attached through an associated local thickness of the substrate, such as in the form of ribs or series of arcuate bulges (not shown) to direct propagation. of breakage along the grooves.

Preferably, the resin of the substrate of the closure tape is compatible with the resin of the structure of the bag, to allow direct welding of the two together. In situations where this is not feasible, a separate layer of compatible bag material could be provided on the closure tape. For example, a layer of paper 142 could be adhered to the front of the fastener tape (eg, at the edge areas 136 in Figure 1), or side-to-side to the rear of the fastener tape, or along only the edges of the back of the fastener tape. The paper 142 could adhere directly to the resin on the substrate (eg, during substrate formation, as described below), or bond with the adhesive after the substrate is formed.

Figure 4 illustrates a method and apparatus for producing the above-described fastener tapes. The method builds on the continuous extrusion roll forming method for casting closure elements on an integral sheet-like base described by Fischer in U.S. Patent 4,794,028, and the lamination line method. contact described by Kennedy et al., in US Patent 5,260,015. The relative position and size of cylinders and other components will not be decreased. An extrusion head 150 supplies a continuous sheet of molten resin to a nip 152 between the rotating mold cylinder 154 and a counter-rotating press roll 156. The mold cylinder 154 contains a set of mold cavities in the form of miniature closure elements that extend inwardly from its periphery (not shown) to mold the closure elements. The pressure in the nip 152 causes the resin to enter the cavities of the closure elements and the substrate to form. The formed product is cooled in the mold cylinder until a receiving cylinder 158 is disposed of

ES 2 267 916 T3 solidified closure elements (eg hooks) from their fixed cavities. Along with the molten resin, a tape of continuous loop material 160 (which becomes a strip of loops 104 in Figure 1) is introduced into the nip 152, where it is partially impregnated with resin and permanently adhered to the front of the substrate. Thus, product 162, which is unmade from the mold cylinder, includes both closure elements and loops.

Figure 4 also indicates some variations of the method described above. For example, rather than introducing the loop material 160 through the nip 152 and thereby bonding it to the substrate when the substrate is molded, the loop material could bond to the substrate after the substrate has been formed, as noted in 160 'loop material series shown with separate lines. In this case, the front pulley 172 is heated and has a molded surface to produce the desired pattern of bond between the loop material and the substrate. The paper could be attached to the back of the substrate by sliding a paper tape 174 between the nip 152 on the side of the resin press roll, or by adhering adhesive covered paper 174 'to the formed substrate on the receiving cylinder. 158 or pulley 176. In some cases, the adhesive covered paper 174 'includes a transfer coating, such that its paper backing could be removed from the adhesive on the back of the product to secure the back of the final product to a supporting surface. . Thus, the adhesive applied to the back of the product could be, for example, a delicate pressure adhesive or heat activated adhesive. To decrease the permeability of the final product, a second flow of resin (molten or in film form) could be added to the nip in front of the press roll 156, as shown by the tape 174, to form a reinforcement on the product. final. For example, a polyester layer could be added to reduce the permeability of the polyethylene closure tape, for example packaging some foods. Adding a tape of barrier material 178 between the loop material and the molten resin optionally controls the penetration pattern of the resin within the loop material at the nip 152. The barrier material 178 is sometimes a paper or Perforated film that allows the resin to enter the loop material in selected areas, but prevents its flow through other areas. The barrier material could also be a homogeneous sheet of material that has high porosity, also limiting the penetration of the resin into the loop material from side to side the width of the barrier material. Rather than being introduced as a separate sheet, the barrier material is applied anteriorly, in some cases, to the surface of the loop material 150 and could take the form of a binder located in discrete areas of the loop material and in the locally wrapped fibers of the material. loop, for example. In many cases, the barrier material is narrower than the loop material, and is centered along the width of the loop material to allow full penetration of the resin into the edges of the loop material. However, in some cases, thin tapes of barrier material pass the nip along the edges of the loop material to prevent bonding of the edge areas to the substrate. Other arrangements of the loop and barrier materials, as well as the resulting joint patterns, will be seen after reading this disclosure. In all cases where the barrier material permanently adheres to the substrate and thus becomes an integral part of the final product, it should be selected for its weight and low material cost.

Figure 5 illustrates a modification of a common VFF machine configuration, to continuously secure the closure tape described above to a flow of bag-forming fabric during the formation and filling of individual bags. The bag-forming fabric consists of a thin paper of thermoplastic film 254 that takes shape within the tube into the filling tube 256, which has an upper funnel end 258 through which the contents are discharged to fall into the tubes. individual bags formed of film. Film 254 is fed from a cylinder (not shown) onto a locating roller, and is conveyed over the filler tube through curved steering shapes 262. In some cases, the film is continuously advanced, and the transverse clamps 264 (described above) correspond vertically, moving with the film during the sealing and cutting method (as indicated by arrows 265); in other cases, the film is advanced stepwise and the transverse clamps remain within the same horizontal plane.

When film 254 is formed within a tube, its two longitudinal edges 268 form ridges that extend generally radially from the tube, between which the continuous extension of closure tape 266 is inserted into a folded fabric, such so that the edge areas of the fabric film meet at least partially opposite the outer sides of the fastener tape face to face, but do not overlap the folded edge of the fastener tape. The guide rolls 270 on the closure heat seal plates 272 maintain the adjacency of the sides of the closure tape and the edges of the film. The closure tape 266 is inserted over a molded insulating bar 274 that extends longitudinally along the filler tube from the upper guide cylinders 270 to the lower heat seal plates 272. As shown in Figures 5A and 6, the insulating bar 274 has a longitudinal slot along each of its sides. One slot contains the loop material 104 to prevent flattening of the extended meshed loops, and the other slot receives the hooks 106 of the fastener tape, helping to guide the fastener tape through the sealing method. The bar 274 also has a hole extending along its distal end, to contain the central clamp rib 132 of the closure tape. The main purpose of the insulating bar 274 is to prevent unwanted welding of the inner sides of the closure tape while the edges of the bag film are welded to the outer surfaces of the closure tape through the heat sealing plates. closure 272 (see Figure 6). When an insulating bar is not used, the fastener tape could be configured to use the insulating properties of the loop material to avoid permanent welding of the interior surfaces of the fastener tape, as will be discussed in more detail below.

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Fastener tape 266 could be wound from cylinder 276 onto guide cylinder 278 into folded fabric, as shown, with its hooks and loops engaged and consequently torn over insulating bar 274, thus separating the hook and loop sections. loops of the fastener tape, or the fastener tape could be wound flat and consequently folded around the insulating bar, thus avoiding having to disengage the hook and loop sections in the method.

Each of the closing heat seal clamps 272 has a longitudinal groove adjacent to the longitudinal grooves of the insulating bar 274, such that the heat seal clamps slidably contact the edge areas of the film only with the side of the hook strips and loops of the closing tape, sealing the film to the closing tape in two differentiated strips on each side of the closing tape. The heat seal clamps 272 have heating elements embedded therein (not shown) to maintain the sealed surfaces at a predetermined elevated temperature. To free the inner edge of the loop side of the fastener tape from the film to form an anti-peel tab, the heat seal clamp 272 is embedded, at least partially, onto the loop side of the fastener tape, as shown, to prevent adhesion of the inner edge of the loop side of the closure tape to the film of the bag. To form an even wider anti-peel tab, the heat seal clamp 272 could be configured on the loop side of the closure to contact the film only outside the band of the loop material 104.

Immediately below the lower edges of the heat sealing clamps 272, the insulating bar 274 terminates and the hook and loop strips of the fastener tape are pressed between a pair of rollers 280, just above the lower end of the filler tube 256.

After pouring a selected amount of content through the lower end of the filler tube, the transverse heat sealing clamps 264 are gathered around the bag film and the closure tape and two parallel transverse seals 284 are formed, each of which will form the sealed edge of a bag. As the clamps 264 circulate with the advanced film, a cutting blade 282 within the clamps cuts the film and the closure tape between the transverse seals 284. When the clamps 264 are opened at the end of the sealing cycle, a bag is concluded cut, filled and fully formed 286. Figure 6A shows another hermetic configuration of a closure tape 288 to edge areas of a film fabric 254 when the film fabric is inserted around the filler tube 256, to create what we refer to as an inverted closure, which has free the outer edges and a recessed central part. In this configuration, the closure tape is guided over a separate insulating bar 290 that extends between the edges of the film and opposite sides of the sealing tape, similar in cross-section to the insulating bar of Figure 6, but in opposite orientation. In this case, the closure tape 288 is provided with a central break hole 292, before a central rib, along which the closure is broken to initially open the bag. In the bag formed with this closure pattern, the hook and loop elements are not exposed to the contents of the bag prior to initial opening, and the central portion of the closure tape provides a tamper evident seal. The closure tape 288 is permanently sealed to the bag film through the heat seal clips 272 ', which are similar in construction to the heat seal clips 272 of Figure 6.

Figures 7-9 illustrate three examples of horizontal form fill (HFF) machines and methods showing the closure tapes described above. Referring first to Figure 7, a bag film 254 is continuously fed from roll 294 over locating roll 296 and into a forming head 298 developed to form the film within a rectangular tube 300. As with the VFF method described above, the edges of the film meet to form a perpendicular flash 302 that extends from one side of the tube. In this case, the closure tape 100 is introduced from the roll 304, folded to engage the hook and loop stripes, overlapped around the angle roll 306, and is inserted into the line of contact between the thermal flat weld bearings 308 and the edges of the bag film. Meanwhile, products 310 to be packaged (eg, cookie trays) are fed through the forming head and into the filler tube 300 at a predetermined space and rate corresponding to the speed of the film.

As shown in Figure 7A, the outer surfaces of the folded closure tape 100 are permanently welded to the extensible film flanges forming the perpendicular flash 302 of the film tube at the line of contact between the flat weld bearings 308. . In this case, the heat sealing clamp is not needed between the inner surfaces of the fastener tape, because the air between the hooks and loops extending from the interior surfaces of the fastener tape produces the stretch weld within the fastener tape. closing. With proper adjustment of the temperature and pressure of the rollers 308, which depends on the type of resin used and the line speed, among other things, at least only a small fraction of the heads of the hook elements will slightly adhere to the stripes from the hooks 106 to the loop material 104 or the resin in which the loop material is embedded. This small amount of welding will advantageously increase the amount of peel force required to initially open the package, leaving a sufficient proportion of hook elements intact to provide proper engagement on the closure. We note that with many hook and loop resins, speeds, temperatures and pressures will have to be carefully adapted and controlled to provide a smooth bond while preventing rapid progression of hook fusion.

Referring back to Figure 7, the folding diagonal separation rollers (not shown) are folded over the flat weld, and a pair of separation rollers 312, carrying a heat seal bar and cutting the foil seal ends of the bags , they break the bags of both.

Figure 8 shows a similar HFF method, in which the closure tape 100 is folded over the

ES 2 267 916 T3 outer edges of the bag film and an insulating flat weld bar 314 extending to just below the thermal flat weld bearings 308. After circulating through the angle roll 306, the tape of closure 100 is folded within a guide channel 316 such that the edges of the closure tape overlap the edges of the film, as shown in Figure 8A. The flat weld bearings weld these overlapping areas on either side of the insulating bar 314, permanently adhering the closure tape to the film of the bag. Since the flat seal is folded before passing between the separation rollers 312, the hook and loop bands of the closure tape are pressed together, before the inner surfaces of the bag film edges are welded on the seals. ends of the bag. The hook and loop strips could also be welded onto the end seals, if desired, providing sufficient heat, pressure, and dwell time from the heat-tight bar portion of the separation rollers that connect to the closure tape at the hook and loop interface.

Figure 9 illustrates the incorporation of a self-closing tape into a more common HFF machine configuration, with the longitudinal flat weld 302 formed on the bottom side of the rectangular film tube 300. As in Figure 18, the closure tape 100 is folded around the outside of the end ridges of the extended film, which are separated through an insulating bar (not shown) that extends across the line of contact between the ends. 308 flat weld bearings.

Figure 10 shows another application for our closure tape in a bag making method. The fastener tape 318 differs from the fastener tape shown in Figure 1 only in that it contains a tear cord 320 (Figure 12) embedded along its midrib 132. The tear cord is configured to break through the fastener tape and the film lengthwise between the hook and loop stripes when torn transversely to the fastener tape, and therefore must have a resistance to Enough tension to tear through the resin of the closure tape without tearing. Suitable tear string materials include stretched nylon, such as fishing line, for example. The tear cord is embedded within the resin of the center rib of the fastener tape by continuously feeding into the rib-forming channel of the mold cylinder prior to introduction of the rib-forming resin (as along of the advance path labeled 178 in Figure 4). Appropriate guides (not shown) are recommended to keep the tear string withdrawn from the rib-forming channel.

The closure tape 318 is passed around a guide roll 324 to circulate the film in the bag 254 over a folding clamp 326, where it is permanently adhered to the film under heat and pressure through a sealing plate 328. As shown In Figure 11, the seal plate 328 lightly engages the closure tape along three stripes, forming three continuous welds 320 between the closure tape and the film 254. Clamp 326 holds the film against the gentle pressure applied through the sealing plate. The channels 332 and 334 contain in the seal plate the band of hooks 106 and the center rib 132 of the fastener tape, and therefore maintain the transverse location of the fastener tape during bonding. The outer edge of the loop side of the closure tape is not welded to the bag film in this example, to provide an inner anti-peel tab on the finished bag, as shown in Figure 12. Other bonding configurations are employed. for different applications.

Once welded, the bag film 254 and the closure tape 318 are folded along their longitudinal centerline and pass between two drive rollers 336 that press the hook and loop bands of the closure tape and they ensure a proper fold along the spine of the fastener tape. The folding of the bag film and the closing tape is carried out by the clamp 326 and a folding pulley 338 that runs through the center of the closing tape and delimits an edge groove 340 to receive the center rib of the tape closing during folding.

The folded bag film is then passed between a pair of cutter clamps and reciprocating heat sealers 342, which close against the outer surfaces of the bag film to seal the two sides of the folded bag film and the sealing tape. closure folded so as to form a series of individual bags, each bag sealed on three sides and having an open end 344 for subsequent filling. The clamps 342 could also be configured to cut the bags from each other during sealing, or to leave the bags connected in the form of bag tape that is easily ripped through a fill and seal station (not shown).

Figure 13 gives an example of a side seal configuration in the bag formed by the clamps 342 of Figure 10, in which a slot and a hole are punched into the vertical seal formed between adjacent bags. The thermal surfaces of the clamps 342 form mold parts for cutting through the bag film and closure tape so that the configuration shown is formed while forming the inner bag seal. The bags are then filled through their open ends, which are subsequently sealed. By cutting the lower segments 350, which are attached adjacently to the bags along the center lines 352, extended tear tabs are formed at the ends of each bag. Each tear tab 354 contains an edge portion of the tear string 320, and provides a practical means of grasping and tearing the tear string through the closure tape throughout the bag, as shown in Figure 14.

In the bag formation method shown in Figure 15, the closure tape 318, already folded in half, is fed from side to side of an angle roll 356 and between the longitudinal edges 358 of the bag film 254 while the film is folded within the clamp 326. A pair of heat seal cylinders 360 continuously seal the edge areas of the pouch film to the overlapping closure tape. The insulating bar is not needed when the loop material of the fastener tape, which in this case is wide enough to extend9

ES 2 267 916 T3 side to side of the entire sealing zone, prevents the joining of the opposite inner surfaces of the closure tape (as will be discussed below with respect to Figures 18 and 19). After passing through the sealing edge clamps 342, the folded edge 362 of the bag film is trimmed along line 364, leaving the ends of the bags opposite the closure tape open to receive the materials to be packed. The series of bags could then be rolled up on a roller to be sold or refilled later.

Figure 16 shows a method of making bags from two separate sheets of bag film and the bag closure tape described above. The upper and lower plastic films 368 and 370, respectively, are continuously unwound, with a pre-folded closure tape or the pre-engaged hook and loop tapes 372, and inserted between them, as shown. An insulating bar 374 extends between the hook and loop tapes, the hooks temporarily disengaging from the loops, while the hook and loop tapes are permanently welded to the respective inner sides of the plastic films between two rotating hermetic rollers 376 ( only the top roller is shown). The transparent closure films and tapes are then welded at spaced intervals through the transverse thermal seal clamps 378, forming side seals between adjacent bags which are then filled from their open ends (not shown) and closed through the upper and lower strips of the hermetic clamps 380 This method is also useful, for example, for forming a series of pre-made bags to be rolled or stacked for later filling.

The bag 382 formed through this method has four side seals 384, as shown in Figure 16A, along with the closure 372. The side seal 384, adjacent and parallel to the closure 372, is torn to open the bag and expose the closing. In another embodiment (not shown), the side seal 384, adjacent and parallel to the closure 372, is omitted, along with the upper band of hermetic clamps 380 in Figure 16, and a folded closure tape is inserted (e.g., the tape 318 of Figure 15) in place of the separate tapes 372, with the fold of the closure tape pointing outward to the adjacent side of the continuous films. In another embodiment, producing an "inverted" closure arrangement similar to that shown in Figure 18, the folded closure tape is inserted between the plastic films with its fold extending from the adjacent edge of the films.

Thicker weld zones can be provided near the edges of the fastener tape. Thickening the closure tape in areas intended to be welded to other bag materials provides more resin available for flow and bonding during welding. In addition, the bulk of the larger fastener tape absorbs more heat and helps to keep the inner surfaces of the fastener tape base welded. Thicker materials are also less sensitive to changes in welding conditions, allowing for a more consistent joint.

Figure 17 shows a closure tape 426 at an upper end of a bag 428, having a band 430 of closure elements with molded hooks extending from its outer surface and exposed to engage the loop fibers. The closure tape could include a tear rib 132 as shown, and be configured to tear the top stripe 430, such that the outer hooks remain on the open bag. Another possibility is that the closure tape could be configured to break between the strip 430 and the top edge of the bag film, in which case the tear rib could be unnecessary. The hooks on the strip 430 are useful, for example, for hanging the bag 428 from an indicator grid covered in loop material. For spinning multiple bags, a loop bonding strip (not shown) could be provided anywhere on the outer surface of the bag, such that strip 430 of each bag engages the exposed loop strip of an adjacent bag of the bag. Stripe. Figure 17 also illustrates an example of an insulating weld loop material arrangement discussed below with respect to Figures 18 and 19.

For some applications, the bag closure is welded between two separate sheets of film to form a bag. Figure 18 shows such a bag closure 462 welded to bag side sheets 464a and 464b, forming what we refer to as an "inverted" closure. The side sheets of the bag extend beyond the closure tape and are welded together to form the top edge 466 of the bag. After the closure tape is adhered to the sides of the bag, and to the side edges of the sealed bag (not shown), the bag is filled from its other end, in the direction of arrow "J", which is then seal to close the bag. To initially open the bag, the edge 466 is torn, breaking the side sheets of the bag along perforations 468. Then, the fastener tape is opened and the fastener tape fabric is torn into two parts along a tear groove 470 in the fold of the fastener strip. To reclose the bag, the loop and hook strips 104 and 106 of the closure tape are simply depressed.

The weld pattern shown in Figure 18 provides the anti-peeling benefits discussed above, while the inner edge of the loop side of the closure tape remains unattached to the side sheet of bag 464b. One method of forming such a weld pattern is shown in Figure 19, in which closure tape 462 is simultaneously welded to both bag side sheets 464A and 464b via thermal clamps 472 and 474, respectively. . Advantageously, the loop material 104 is fixed on the folded closure tape to overlap the inner and outer closure tape welding zones, preventing any permanent welding to the sides of the closure tape. For applications where a small amount of bonding between the inner surfaces of the closure tape is acceptable (or desirable), a 476 cooled clamp, facing the side of the bag loop adjacent to the inner weld zone, prevents any Inadvisable bonding of the inner edge of the closure loop side to the bag side sheet 464b.

As an alternative to applying the closure tape to the bag film when forming the film within the bags, the closure tape could be pre-applied to the bag film, and both wound onto the rollers. Configu19

ES 2 267 916 T3 rations of this type are especially useful in the subsequent formation of bags on standard bag making machines not equipped for ordering closure tapes. For example, Figures 20A through 20C show rolled film products consisting of a continuous sheet of thin plastic film permanently adhered to one or more continuous lengths of the closure products. In Figure 20A, closure tape 318 is centered on bag film 254, to form, for example, bags with the method illustrated in Figure 10. In Figure 20B, closure tape 444 is expanded along along one edge of bag film 446 to form rolled product 482. In Figure 20C, separate extensions of hook and loop products 484 and 486, respectively, adhere to opposing edges of film 488 to form rolled product 490, which could go through the fill and loop forming methods. patterns so that releasable fasteners are incorporated within the longitudinal flat welds.

Referring to Figure 21, the bag 500 consists of a piece of polyethylene bag material folded once to form the bottom edge 502 of the bag, attached to a closure 504 to form the top edge 505 of the bag, and sealed. permanently along the two remaining sides 506 and 508 by welding the material from the front of the bag to the material from the rear of the bag. Although illustrated as a flat bag, the bag 500 could be constructed in other ways, a bag, for example, with a bottom folded end to position the bag vertically on its bottom edge.

Referring to Figure 22, to initially open the sealed bag, the upper edge 502 is grasped with one hand 510 and the front of the bag is grasped with the other hand 512, on either side of the tear channel 514 extending along length of closure 504. By grasping or squeezing only the front of the bag with one hand 512, and not the rear of the bag, tearing the front of the bag from the top edge, a large side-to-side extensible load is placed on the channel 514, propagating a tear along channel 514 creating an opening 515 within the bag.

As shown in Figure 23A, the bag material from the rear side 516 of the bag is welded to the rear side (ie, non-closure) of the automatic closure 504 to 516. The material from the front side bag 520 of the bag is welded to the closure along the leading (ie, closure) side edge 522 area of ​​closure 504. With the closure so tightly attached to the bag material, and sealed along the sides of the bag (see Figure 21), the closure provides an airtight seal at one end of the bag.

The front of the closure 504 carries a strip 524 of fibrous loops, in non-interlaced form and partially embedded within the base resin of the closure, and a strip 526 of closure elements in the form of hooks molded out of the resin of the base in series that run the length of the clasp. After initially being opened by separately tearing the closure along the slot 514, the bag could be reclosed, folding its top edge around the opening created by breaking the closure, releasingly engaging the closure 524 of the loops with the closure 526 of the loops. hooks (Figure 23B).

Referring to Figure 24, another method of making bags is shown by applying closure tape in differentiated lengths from side to side of the bag film (ie crosswise), rather than lengthwise, as described above. The film from bag 254 is unwound from a roll 570 and through filler tube 256 onto guide forms 262, as previously described with respect to Figure 5. However, in this case, the individual lengths 572 of the closure tape rise from side to side of the bag film and are permanently attached to the film, for example being thermally welded at intervals of the length of the bag. Tightening of the closure tapes preferably occurs while the film in the bag is stopped between rises of the film, while, for example, a bag is sealed and ruptured at the lower end of the tube. Thus, the inclusion of the closure tapes requires very few modifications to the bag making apparatus. As an alternative to adjusting the closure tapes 572 to the bag film 254 as it is unrolled within the bag making apparatus, a roll 570 could be provided with closure tapes previously applied at suitable intervals.

Referring also to Figure 25A, the closure tape 572 is in one example folded over on itself while attached to the bag film 254, with the hook and loop bands engaged to maintain the closure in its folded condition. One side of the closure tape is welded to the bag film in zones 574, while the other side of the closure strap is left unattached until it is welded to an opposite surface of the bag film below the filler tube (eg, sealing bars 264). Thus, the closure tape 572 is positioned at one end of the final bag, with its fold directed outward or inward, as desired. The sides of the bag could be joined to form the adjacent end edge of the bag so as to create an additional end seal. If it is required to keep the closure tape in its folded condition while the film in the bag is raised over the filler tube, the ends of the closure tape could be basted together.

An alternative closure tape configuration is shown in Figure 25B. In this case, the fastener tape 572 'is supplied as two separate fastener straps (a band of loops 576 and a band of hooks 578), which intermesh with each other along their length. Both closure tapes are permanently affixed to bag film 254 along weld lines 574, on either side of tear line 580 (eg, a series of perforations or a continuous mark) in the film of bag 254. The closure tape 572 'could be positioned in the final bag at any point along the length of the bag, which is opened by breaking the tear line 580 and separating the loop and hook stripes from the closure strips 576 and 578 The bag is resealed by pressing the hook and loop strips.

Referring to Figures 26A and 26B, closure tapes 582 and 584 are advantageously provided with tear-off seals 586 that act as secondary closure means. Tear-away adhesives are well known in the art, and they provide an airtight seal that is relatively easy to

ES 2 267 916 T3 open without breaking the underlying substrate. In some cases, the seal 586 is of a material that effectively renders tack-free when initially opened. In other cases, the seal 586 is made of a material that retains its tack to continue to provide some seal when the bag is resealed. In the closure tape 582 (Figure 26A), the tear-off seal 586 is located within the main hook and loop closure 588, to protect the loop and closure elements from contamination of the bag contents. On the closure tape 582 '(Figure 26B), the tear-off seal 586 is located on the outside of the main hook and loop closure 588, and must be opened to access the main closure. The tear seal could be formed by applying a tear adhesive, such as a soft pressure adhesive, to the front of the closure tape. In some cases, the adhesive is applied in two distinct areas on the surface of the tape, in such a way that the adhesive from the two areas comes together to form the seal. Tear-off seals of this type can provide greater preservation of the bag's contents (ie, a longer shelf life after the bag has been initially opened).

Referring to Figure 27, a fastener tape 590 has hook-shaped fastener element attachment stripes 592. In a stripe, extending from one side 594 of the fastener tape, the fastener elements are all oriented to the left, while from the other side 596 of the closure tape the closure elements are all oriented to the right. As the strips of the closure elements 592 are more pressed from the position shown, the heads of the hook-shaped closure elements interlock to interlock the two strips of elements. When torn apart, the flexible heads are extended to clear the heads of the other band of elements and to then regain their original hook shape. This is an example of what is known in the closure sector as "self-adhesive" closures, those in which the interlocking closure elements are of a similar structure. Other forms of self-adhesive fasteners include fungi, for example, the "DUAL-LOCK" closure product available from Minnesota Mining and Manufacturing Inc. With self-adhesive hook fasteners, we prefer to mold the hooks to be thicker "T_h"That the spacing" S_R”Between the series of adjacent elements (as shown in Figure 28), such that the stripes cannot be separated by moving one side of the closure tape sideways from side to side of the series of closure elements on the other side of the closure tape. The CFM-15 and CFM-29 hook shapes marketed by Velero USA in Manchester, New Hampshire, can be useful for self-adhesive closures. The hook-shaped closure elements should be spaced throughout their series so as to provide sufficient space for the heads of a series of hook attachment to extend between adjacent hooks in the series. Optimal spacing will depend on the selected hook shape and the desired gear force. With joint assemblies of mushroom-type closure elements, the mushroom density of the opposing assemblies should be different to avoid "empty travel" to the mushrooms (ie, forcing the mushroom heads to deform before they their tubes twist). One set could have, for example, a closure element density of approximately 50 to 200 closure elements per square inch (8 to 31 per square centimeter), while the density of the closure elements in the other set reaches approximately 500 to 2,000 (78 to 310 per square centimeter). Optimum density sets will feature the desired gear and load disengaged, among other things. The self-adhesive strips of fasteners could be substituted for the loop and hook strips of any of the fastener tapes described above to form self-adhesive fasteners for different applications.

Preferably, whether or not hook and loop stripes or self-adhesive fastener stripes are employed, the fastener attachment stripes are advantageously configured to engage with very low engagement force. We calculate the engagement force by measuring the required lateral load between the attachment means of a one-inch long length of fastener tape to engage the fastener. The disengagement peel force is calculated when loading is required to separately peel such a 25 millimeter (one inch) fastener tape. The closure can provide an advantageously low engagement force of, for example, less than about 0.18 Newton over a linear millimeter (one pound over a linear inch) of the closure, and a low disengagement peel force of less than about 0 , 35 Newtons per linear millimeter (two pounds per linear inch).

Materials other than polyethylene could be used, such as polypropylene, polyester, nylon, and other thermoplastics and their copolymers. For example, coextruded or laminated bag films can have interior surfaces of a welded material compatible with the closure base material, and an exterior surface of a material selected for other properties, such as durability or waterproofing.

As evident from the embodiments described above, these closure tapes are useful in many packaging applications, to provide an easily engaged releasable closure that does not require perfect alignment during closure. The closures are useful for packaging food, such as cookies, candy bars, and even products, and could be located at a sealed end or along a longitudinal seam of the package. By “bag” we propose to include all packages with flexible sides, but not limited to expandable bags and flexible cartons.