EP1714894A1 - Sealing strip, associated foil packaging and methods for their manufacture - Google Patents

Abstract

The sealing strip (3) for production of reclosable multilayer foil packaging units (10) comprises an adhesive layer (3a) whose adhesive strength is lower than the sealing strength of the sealing material. Independent claims are also included for: (A) an application of the proposed sealing strip for production of reclosable foil packaging units; (B) a reclosable foil packaging unit; (C) a method for producing such packaging units.

Description

The invention relates to a sealing strip for the production of a sealable by means of an integrated pressure-sensitive adhesive after tearing seal on a film packaging, its use for the production of film packaging, and a film packaging, in particular a film tube bag, with at least one sealing strip containing the sealing strip and an associated manufacturing method.

Film packaging has found industrially diverse application because they are lightweight, hygienic and liquid-tight, possibly also gas-tight. It is also possible to make the film packaging visually appealing and to print. A common perceived disadvantage of film packaging is that a tightly sealed package can be difficult to open and often unpredictably ruptures in an undesired manner, completely destroying the package. This disadvantage becomes a problem if the packaging is still needed for further storage of the contents or residual contents.

Film packages are often joined by heat sealing seams. The film packaging material carries at least one side of a fusible surface layer, so that e.g. two provided with such a sealing layer and against each other laid film webs or sections with a sealing tool accurately welded, i. sealed, can be. Such sealing layers can be sealed tightly so that opening of the seam is practically no longer possible since previously the packaging film itself will rupture.

In order to be able to open film packaging nondestructively, sealing layer materials have been developed which, while ensuring a secure closure of the packaging, but by tensile forces that are smaller than necessary for tearing the base film, detached from each other, ie can be deducted. Such sealing layers and seams are also referred to in the jargon as "peelable". From the EP 1 074 477 It is also already known to produce a peelable sealed seam by inserting a peelable film strip.

However, peelable sealing seams have the disadvantage that the packaging can be opened neatly and non-destructively, but can not be closed again. One way to further protect the contents of the package is to reseal the package with a pressure-sensitive adhesive strip. The adhesive strip, which is partially covered with protective film (release film or paper), can already be stored on the still closed packaging; associated examples are i.a. known from tobacco pouches. The disadvantage, however, is that the packaged good is generally not so complete, e.g. also airtight, protected as would be desirable.

Another elegant solution for reclosing was seen to be to integrate the pressure-sensitive adhesive strip virtually into the packaging film and, for example, to equip the packaging film itself with an exposable full or partial pressure-sensitive adhesive layer. However, the integration of the pressure-sensitive adhesive can also take place in such a way that a film strip in which the pressure-sensitive adhesive layer is covered on both sides is applied to the packaging film or introduced during the production of a packaging. The reclosure of film packaging by means of pressure-sensitive adhesive-containing multilayer film strips is therefore basically known in the prior art.

So revealed the DE 101 09 209 A1 a plastic film bag, which is closed with a applied in a closure zone multilayer film strip. The film strip consists of a carrier layer, which is welded to the film material of the plastic film bag in a first film section of the closure region, a pressure-sensitive adhesive layer over the carrier layer and a sealing layer, which covers the pressure-sensitive adhesive layer and on the opposite film section of the film bag over a portion of Strip width is sealed.

Corresponding stripes are also from the WO 96/40504 or the FR 2783512 known.

In the pressure-sensitive adhesive-containing sealing strips known in the prior art, a predetermined crack region is created within the strip, which opens the sealed seam while exposing the pressure-sensitive adhesive. For this purpose it is provided that a brittle set tear-resistant layer, for example of an ionomer in the immediate vicinity of the pressure-sensitive adhesive layer is present, or that the adhesive layer adjacent to the sealing layer itself is set brittle to allow at this point tearing of the strip in itself, such as this eg in the WO 96/40504 or in the DE 101 09 209 is described in more detail.

The results that can be achieved with the previously known pressure-sensitive adhesive sealing strips are unsatisfactory. In principle, since cracking is provided at a predetermined crack site within or on a brittle layer, there is the possibility that the crack course is uneven, that fraying crack edges are formed, which act as spacers between the surfaces to be resealed, or that remnants of the brittle tearable layers in FIG Form of small shreds remain on the pressure-sensitive adhesive layer and hinder the adhesion lasting.

The object of the invention is therefore to form a heat-sealed seam on a film package, in particular a film bag, which is located at a position at which the package is to be opened so that the package by loosening the seam as intact as possible and in any case non-destructive opened and afterwards with the help of the suture provided pressure-sensitive adhesive can be closed again.

To solve this problem, the invention initially provides a sealing strip which can be placed in a heat-sealed seam and thus enables the desired packaging properties at the seam.

The sealing strip according to the invention for the production of a sealable by means of an integrated pressure-sensitive adhesive after tearing seal on a foil packaging is multi-layered and has an internal pressure-sensitive adhesive layer and on both outer surfaces each have a sealing layer, wherein the pressure-sensitive adhesive layer to at least one of the outer sealing layers in direct, full-surface contact and the properties of the pressure-sensitive adhesive layer and the sealing layer in contact with it are coordinated so that the adhesive force of the pressure-sensitive adhesive layer is smaller than or equal to 10 N / 15 mm of strip width and the seal strength is greater than the bond strength, and further wherein none of the layers outside the pressure-sensitive adhesive layer is a brittle or tear-able layer to give a predetermined crack area within a layer of the strip.

As a result, the double-sided sealed strip in the application position will rupture within the pressure-sensitive adhesive layer or at the contact surface of the pressure-sensitive adhesive layer to form an adjacent sealing layer. In any case, a fully adhesive adhesive layer will be revealed, while the sealing layers of the sealing strip also remain firmly bonded to the packaging material over their entire surface due to their greater sealing strength. Unclean or frayed cracks or stretched film areas that affect the bag shape and reclosure are safely avoided.

The invention is based on the finding that it is not necessary, as has hitherto generally been assumed in the prior art, that the adhesive force of the pressure-sensitive adhesive layer must be greater than the tear strength of one of the sealing layers, which make it possible to open the packaging due to their brittleness and tear strength and at the same time expose the adhesive. Rather, in the course of the invention, much better results could be achieved if the adhesive force (adhesive force to an adjacent surface or cohesive force) of the pressure-sensitive adhesive layer is large enough to ensure a relatively tight reclosure of the package, but above all the seal strength as well as the tear strength the adjacent sealing layer or sealing layers larger, preferably significantly greater than the adhesive force of the pressure-sensitive adhesive layer.

Preferably, the seal strength of at least the sealant layer adjacent to the pressure sensitive adhesive is more than twice the adhesive force of the pressure sensitive adhesive.

The adhesive force may be the force of adhesion of the adhesive to a planar surface or cohesive force within the adhesive itself, depending on the type of adhesive. Preferably, the pressure-sensitive adhesive used for the invention is one to Cohesive fracture prone adhesive. This property can be adjusted by adhesive technology.

Practically, the bond strength is determined in relation to the stripe width, i. a strip according to the invention, for example having the structure: sealing layer / pressure-sensitive adhesive layer // sealing layer, is pulled apart and the force required for this purpose is determined. The determination is carried out in a composite adhesion tester and corresponds to DIN standard 53 357, method B. The bond strength should be less than or equal to 10 Newton with a strip width of 15 mm.

The lower limit for the sensible manner to be set adhesive force of the pressure-sensitive adhesive results from the application of the film packaging. If hardly any external forces can act on the package, a lower adhesive force is sufficient. If, for example, it is to be expected during transport and storage that pressure is exerted on the packaging, the adhesive force must be greater so that the sealed seam can not burst with the adhesive. For most applications, adhesive forces between 5 and 10 N / 15 mm strip width will suffice.

For the pressure-sensitive adhesive layer are also known as such adhesive materials, in particular the pressure-sensitive permanent adhesives, such as hotmelts, e.g. on the basis of styrene / butadiene block copolymers or styrene / isoprene / butadiene block copolymers or as UV-crosslinking hotmelts or as pressure-sensitive adhesives based on dispersions (eg acrylic resins or natural or synthetic rubber) are currently available for dispersion adhesives acrylic acid and / or Methacrylic acid copolymers, in particular acrylic acid and / or methacrylic acid-styrene copolymers are preferred.

The sealing layers, in particular at least the sealing layer directly adjacent to the pressure-sensitive adhesive from one side, preferably consists of olefinic homopolymers or copolymers, more preferably of LDPE, HDPE, LLDPE, m-PE, ethylene / vinyl acetate copolymer, polypropylene homo- or copolymers , Polyester homo- or copolymers or mixtures with or from the polymers mentioned. the two sealing layers present in the strip can be of the same or different composition and / or composition.

Both sealing layers can be directly adjacent to the pressure-sensitive adhesive layer, so that a 3-layered, by avoiding additional layers particularly thin sealing strips is formed.

At least one side between pressure-sensitive adhesive layer and sealing layer, a (tear-resistant) carrier layer may be provided. This carrier layer, if used, serves the mechanical stability of the strip. A relatively stiff material is chosen so as to increase the stiffness of the entire strip, which can further increase the unwinding properties of the strip during processing. This is achieved in particular by thin, stretched films, so that the carrier film is preferably a bi- or monoaxially oriented film of polypropylene (PP), polyethylene terephthalate (PET) or polyamide (PA) or of mixtures formed with or between these polymers (as base polymers) or copolymers.

The sealing layer can also be coextruded in a multilayered manner and contain a sealing layer on both sides outside and at least one functional layer on the inside. In particular, it may be a stiffening and / or barrier layer, which may for example consist of EVOH. Such layers are known in the art and are also referred to as "seal barriers".

The pressure-sensitive adhesive layer should have a thickness of 5 to 30 μm, preferably 10 to 20 μm, particularly preferably 10 to 15 μm. At least the sealing layers adjacent to the pressure-sensitive adhesive layer should preferably have a thickness of 20 to 50 μm, more preferably 20 to 30 μm. The specified sealing layer thickness ensures that sealing pressure and sealing time can be set so that the sealing layer is only fused to such an extent that the adhesive layer is not subjected to thermal stress too much. It is presently considered preferable if the pressure-sensitive adhesive layer is thinner than the adjacent sealant layer.

Overall, the sealing strip according to the invention preferably has a thickness of 50 to 150 .mu.m, wherein the thickness of the pressure-sensitive adhesive layer is less than one third of the total thickness and the internal pressure-sensitive adhesive layer by at least one Quarter of the total thickness is spaced from the surfaces of the sealing strip.

In general, the strip will be made up as a roll material running several hundred meters, preferably> 1000 m, with a substantially uniform width of 10 to 20 mm. The sealing strip is produced in such a way that a film web with the desired layer sequence is cut into strips. This also ensures that the contact surface between the layers is full-surface and not the adhesive strip of both sealing layers is enclosed at the edge, which would affect the functionality of the strip.

The sealing strip can be produced by applying an adhesive resin by hot extrusion and thus connecting the films involved.

Another possibility is to apply the adhesive layer hot on a stretched carrier film and to calender the other layer.

Likewise, a total coextrusion is possible, in which one coextrudes the sealable outer layers together with the adhesive layer as a blown or flat film. Other ways of producing the sealing strip are to apply the adhesive as a solution or aqueous dispersion to a carrier web, to dry and then to connect with the other layer.

Furthermore, a lamination can be carried out with a low-viscosity UV-crosslinkable self-adhesive which is crosslinked by the UV radiation before or during the processing process.

In all cases, after the production of the films, a cut of the sealing strip on the scope of application.

The above-described sealing strip according to the invention is intended for use in the manufacture of a reclosable film package, within a sealed seam which would be a permanent, non-peelable seam without the strip.

The object of the invention is therefore further achieved by a film package, in particular a film tube bag, with at least one sealed seam, which is provided for opening and re-closing of the package and in which in the sealed seam along the sealing direction provided on both sides with a sealing film strip after the Invention is sealed.

The package may have on the side facing away from the closed bag volume side of the seal provided for opening a, for example, tab-shaped rupture aid or a seam projection to facilitate the tearing of the seam and thus of the bag.

The seam provided for tearing can be a top seam or transverse seam of a tubular bag, but also a tubular bag longitudinal seam, in particular a fin seam. For a / b-lengthwise seam a tear-open would be recommended.

It can also be provided several seams to open and thus tearing, for example, two corner seams for tearing, for example, an all-round bag sealed at one corner may be provided with the sealing strip according to the invention, either over the entire seam length or at least in the area Corner.

The invention also encompasses a method for producing a film tubular bag which can be resealed after opening a sealing seam provided for this purpose, wherein the tubular film bag is produced in a manner known per se and a sealing strip according to the invention is inserted during the sealing of at least one sealed seam provided for opening and reclosing the package.

Preferably, the production of the film tubular bag is done in a continuous process in which at least one film web runs off a roll and the sealing strip is fed from a separate roll or spool continuously at the speed of the film web or runs off the reel or spool.

The seal provided for opening may be a fin seam or an a / b stitch, i. Such a seam, in which - based on the finished bag - a film area with its inner or lower side (b) on an outer or upper side (a) is sealed. Preferably, a projection is present at the seam, which serves as a handle and facilitates the user tearing. The sealing seam provided for opening and reclosing can also be formed as a blind seam, which is exposed for opening by the consumer with a pair of scissors or with a tear strip optionally applied during the packaging process. A removal of the contents and subsequent resealing of the pack is thus possible.

EXAMPLES I) sealing strips

Examples of the layer sequences of sealing strips according to the invention are given below.

Example 1)

• 30 µm LDPE-Blasfolie
• 15 µm Haftklebstoff
• 30 µm LDPE-Blasfolie

Streifenbreite: 20 mm, SF = 30 N/15 mm; KF = 8N/15 mm, KF: Klebkraft,
SF: Siegelfestigkeit
Herstellung:

• a) durch Coextrusion aller 3 Schichten
• b) durch Kaschieren (Haftklebstoffkaschierung)

• 30 μm LDPE blown film
• 15 μm pressure-sensitive adhesive
• 30 μm LDPE blown film

Strip width: 20 mm, SF = 30 N / 15 mm; KF = 8N / 15 mm, KF: bond strength,
SF: seal strength
production:

• a) by coextrusion of all 3 layers
• b) by laminating (pressure-sensitive adhesive lamination)

Example 2)

• 30 µm LLDPE-Blasfolie
• 2 µm 2-komponentiger Polyurethan-Kaschierklebstoff
• 12 µm biaxial orientiertes Polyethylenterephthalat
• 20 µm Haftklebstoff
• 25 µm LDPE-Blasfolie

Streifenbreite: 12 mm, SF = 35 N/15 mm, KF = 10 N/15mm

• 30 μm LLDPE blown film
• 2 μm 2-component polyurethane laminating adhesive
• 12 μm biaxially oriented polyethylene terephthalate
• 20 μm pressure-sensitive adhesive
• 25 μm LDPE blown film

Strip width: 12 mm, SF = 35 N / 15 mm, KF = 10 N / 15mm

Example 3)

• a) klebstoffkaschierte Folie (Siegelschicht) aus:
  • 40 µm LDPE-Blasfolie
  • 2 µm 2-komponentiger Polyurethan-Kaschierklebstoff
  • 27 µm monoaxial orientiertes Polypropylen
• b) 17 µm Haftklebstoff
• c) Coextrusions-Blasfolie (= modifizierte Siegelschicht) aus:
  • 10 µm LDPE
  • 2 µm Haftvermittler
  • 3 µm EVOH
  • 2 µm Haftvermittler
  • 10 µm LDPE

a), b) und c) verbunden durch Haftklebstoffkaschierung
Streifenbreite: 10 mm; SF = 30 N/15 mm; KF = 8 N/15 mm

• a) adhesive-laminated film (sealing layer) of:
  • 40 μm LDPE blown film
  • 2 μm 2-component polyurethane laminating adhesive
  • 27 μm monoaxially oriented polypropylene
• b) 17 μm pressure-sensitive adhesive
• c) coextrusion blown film (= modified sealing layer) of:
  • 10 μm LDPE
  • 2 μm adhesion promoter
  • 3 μm EVOH
  • 2 μm adhesion promoter
  • 10 μm LDPE

a), b) and c) connected by pressure-sensitive adhesive lamination
Strip width: 10 mm; SF = 30 N / 15 mm; KF = 8 N / 15 mm

Example 4)

• a) klebstoffkaschierte Folie (Siegelschicht) aus:
  • 30 µm PP/PE-Copolymer,
  • 36 µm biaxial orientierter Polyester,
• b) 10 µm Haftklebstoff
• c) 30 µm PP/PE-Copolymer,

a), b) und c) verbunden durch Haftklebstoffkaschierung
Streifenbreite: 15 mm; SF = 20 N/15 mm; KF = 10 N/15 mm

• a) adhesive-laminated film (sealing layer) of:
  • 30 μm PP / PE copolymer,
  • 36 μm biaxially oriented polyester,
• b) 10 μm pressure-sensitive adhesive
• c) 30 μm PP / PE copolymer,

a), b) and c) connected by pressure-sensitive adhesive lamination
Strip width: 15 mm; SF = 20 N / 15 mm; KF = 10 N / 15 mm

As the pressure-sensitive adhesive, a commercially available hot melt adhesive based on an SBS block copolymer was used (for example, SBS block copolymer / resin blend LUNAMELT®, H.B. Fuller GmbH, Lueneburg). Alternatively, other pressure-sensitive adhesives may be used, e.g. based on thermoplastic synthetic rubber (e.g., INDAMELT®). It is advantageous if the pressure-sensitive adhesive is stable to processing at elevated temperature, for example between 100 and 120 ° C.

Determination of composite adhesion: according to DIN 53357, method B

Bonding is understood to mean the maximum value of the force necessary to sever the test strip in 15 mm width to a length of 10 mm at a separation angle of 90 ° (mechanical) splitting. The bond strength (here KF for bond strength, SF for seal strength) is given in Newtons (N), the strip width is added as an index (e.g., N / 15 mm). The take-off speed is 100 mm / min.

II) tubular bag with sealing strips Example II.1)

For a vertical tubular bag (1a), which is produced from bi-axially oriented polypropylene film which can be sealed on both sides, a sealing strip is partially sealed on the packaging machine in front of the forming shoulder transversely to the film running direction. This happens rapportgerecht in the area of the later top seam.

a) P/E ― Copolymer

20 µm

b) Haftschmelzkleber

10 µm

c) P/E ― Copolymer

20 µm

The 15 mm wide sealing strip is a coextruded blown film processed into coils:

a) P / E copolymer

20 μm

b) hot-melt adhesive

10 μm

c) P / E copolymer

20 μm

The propylene / ethylene copolymers are equipped with the usual antiblocking and lubricants and correspond to those used in BOPP production. The pressure-sensitive adhesive used is a mixture of SBS block polymers with an aliphatic hydrocarbon resin and other resins and oils, as well as antioxidants and stabilizers. The viscosity at 175 ° C according to DIN 53018, Brookfield, Sp. 27 is> 9000 mPa.s.

The length of the sealing strip required for the top seam is cut off from the spool on the packaging machine and sealed as described. The result is a tubular bag, in which the sealing strip is in the sealed seam.

Example II.2)

• a) Siegelbarem biaxial gerecktem Polypropylen (handelsüblich sind oft beide Seiten einer BOPP-Folie siegelbar. Die zur Haftschmelzkleberschicht zugewandte Seite ist für die Anwendung irrelevant und kann vernachlässigt werden.     20 µm
• b) Haftkleber (wie Beispiel I)     10 µm
• c) wie a)     20 µm

For a vertical tubular bag (1a), from biaxial polypropylene film which can be sealed on both sides, a sealing strip is partially sealed on the packaging machine in front of the format shoulder transversely to the direction of film travel. In contrast to Example I), the sealing strip is not present as a coil but as a roll. The width of the roll corresponds to the later length of the top seam. On the packaging machine, the 15 mm required for the seam is cut off and applied. The foil for the sealing strip consists of:

• a) Sealable biaxially oriented polypropylene (commercially available are often both sides of a BOPP film sealable.) The side facing the adhesive hot melt layer is irrelevant for the application and can be neglected
• b) pressure-sensitive adhesive (as Example I) 10 microns
• c) as a) 20 μm

The result is a tubular bag, in which the sealing strip is in the sealed seam.

Example III.3)

• a) Blasfolie aus LLDPE/EVA, siegelbar     35 µm
• b) Haftkleber (s. Beispiel I)     10 µm
• c) längsgerecktem Polypropylen     38 µm
• d) Blasfolie aus LLDPE/EVA, siegelbar     35 µm

For a horizontal tubular bag for packaging cheese made of a biaxially oriented polyamide (15 microns) adhesive coated against a sealing layer of a mixture of LLDPE and EVA (35 microns) is partially sealed on the packaging machine a sealing strip in front of the format shoulder along the direction of film travel. The sealing strip is in coil form and consists of:

• a) blown film of LLDPE / EVA, sealable 35 microns
• b) Pressure-sensitive adhesive (see Example I) 10 μm
• c) longitudinally stretched polypropylene 38 μm
• d) Blown film of LLDPE / EVA, sealable 35 μm

The preparation takes place by laminating the longitudinally stretched polypropylene with a blown film by means of pressure-sensitive adhesive.

On the packaging machine, a tubular bag with a blind seam, which is exposed to open by the consumer with a pair of scissors or with a tear-off strip optionally applied during the packaging process. A removal of individual slices and subsequent resealing of the pack is thus possible.

• Abb. 1:     Schlauchbeutel, Siegelstreifen in der Kopfnaht;
• Abb. 1a:     schematische Ansicht des Schlauchbeutels von hinten,
• Abb. 1b:     Ausschnitt: Variante mit doppelter Kopfnaht;
• Abb. 1c:     Ausschnitt: Querschnitt durch Kopfnaht;
• Abb. 2:     Schlauchbeutel, Siegelstreifen in der Rücknaht;
• Abb. 2a:     schematische perspektivische Ansicht des Schlauchbeutels mit eingestülpter Seitenfalte,
• Abb. 2b:     schematische Ansicht: Beutelquerschnitt quer zur Seitenfalte.

The structure and the production of possible tubular bag forms will be explained below with reference to figures. Show it:

• Fig. 1: tubular bag, sealing strip in the top seam;
• Fig. 1a: schematic view of the tubular bag from the rear,
• Fig. 1b: Detail: variant with double top seam;
• Fig. 1c: section: cross section through top seam;
• Fig. 2: tubular bag, sealing strip in the backseam;
• Fig. 2a: schematic perspective view of the tubular bag with inverted side fold,
• Fig. 2b: Schematic view: Bag cross-section across the gusset.

The Figure 1 shows a generally designated 10 tubular bag with two transverse or head seams 1 and a longitudinal or back seam 2, which is designed here as a fin seal in b / b seal. When processed on a vertical tubular bag machine, the upper b / b-sealed transverse seam is generally referred to as the top seam 1 'and the bottom transverse seam as the bottom seam 1/2'. At the position of the top seam 1 ', a sealing strip 3 is sealed in, which is introduced by a laterally intermittently feeding unwinding device.

In the example according to FIG. 1a, the sealing strip 3 is sealed into the bag head seam 1 'in such a way that the sealing strip 3 projects beyond the sealing seam in its width, but remains completely covered by the bag film. The seam 1 'is thus narrower here than the sealing strip 3. The bottom seam 1 ", which does not contain a sealing strip 3, can be made wider, but the head and bottom seams can also be made the same width.

In the embodiment according to Figure 1b above the top seam 1 'is another top seam 1a with b / b seal. This can be formed according to the bottom seam 1 "wider than the now inner top seam 1 ', for example, the seams 1a and 1" 15 mm wide, the sealing strip 3 also 15 mm and the overlying top seam 1' 12 mm. Between the outer top seam 1a and the inner top seam 1 'tear-off aids 4 are provided laterally, since the entire outer top seam 1a should be demolished when opening the bag. The back seam is therefore formed in this example with overlap of the film web edges as a / b-seam 2a, to allow easier tearing or cutting of the outer top seam 1a. The supernatants on the original inner top seam 1 'now offer a grasping possibility for tearing the inner top seam 1', wherein the sealed adhesive strip tears so that the outer sealing layers of the adhesive strip 3 remain sealed by the seal strength to the seal seam 1 'on the foil bag material and the pressure sensitive adhesive in the center of the sealing strip 3 is exposed. It is now possible to re-seal the bag in order to protect, for example, residual contents.

Figure 1 c shows the embodiment according to Figure 1a in sections in the region of the top seam 1 'in cross section. Inside the here three-layered sealing strip 3 is the pressure-sensitive adhesive 3a, so that the sealing seam 1 'is interrupted by the pressure-sensitive adhesive of the sealed sealing strip 3. The sealing layers of the sealing strip 3 adjacent to the pressure-sensitive adhesive 3a are heat-sealed within the top seam 1 'with the bag material of the tubular bag.

Figure 2 shows a tubular bag made on a horizontal tubular bag machine with retracted gussets and sealing strips in a laterally offset back seam.

The figure 2a shows a schematic perspective view of the total again designated 10 tubular bag. On one side of the sealing seams 1 (head and bottom seam), which are b / b-sealed, an inserted side gusset 5 is formed. This gusset is used in use of the bag as retracted bag bottom (bottom fold) to give the bag volume or possibly also stability. The back seam 2 is a fin seam in b / b-seal. In the manufacture of the tubular bag, the sealing strip 3 is allowed to run into the back seam 2 during its sealing.

As can be seen more clearly from FIG. 2b, the projections 6 of the film web material on the fin seam 2 form grasping aids for opening the fin seam 2, wherein the sealing strip 3 ruptures in or on the pressure-sensitive adhesive layer, while the adjacent sealing layers of the sealing strip 3 remain connected to the film web material. The fin seam 2 (backseam) is in turn narrower than the sealing strip 3.

Claims (17)

Sealing strip for the production of a sealable with the aid of an integrated pressure-sensitive adhesive after tearing seal on a film package which is multi-layered and has an inner pressure-sensitive adhesive layer and on both outer surfaces each have a sealing layer, characterized in that the pressure-sensitive adhesive layer to at least one of the outer sealing layers in direct , full-surface contact, and the properties of the pressure-sensitive adhesive layer and the sealant layer in contact therewith are matched so that the strip sealed in the application position within the pressure-sensitive adhesive layer or at the contact surface of the pressure-sensitive adhesive layer ruptures into an adjacent seal layer by making the adhesive force of the pressure-sensitive adhesive layer more similar 10 N / 15 mm strip width and the seal strength is greater than the bond strength, wherein none of the layers except the pressure-sensitive adhesive layer has an i The tear-able layer is that it provides a predetermined crack area within a layer of the strip. Sealing strip according to claim 1, characterized in that the sealing strength of at least the sealant layer adjacent to the adhesive layer is more than twice as large as the adhesive force of the pressure-sensitive adhesive. Seal strip according to claim 1 or 2, characterized in that the Haftklebstofschicht consists of a pressure-sensitive permanent adhesive and preferably a hot melt, in particular based on styrene-butadiene block copolymer or styrene / isoprene / butadiene block copolymers, or containing a Warmmelt or a dispersion adhesive. Sealing strip according to one of Claims 1 to 3, characterized in that the sealing layers consist of olefinic homopolymers or copolymers, preferably of LDPE, HDPE, LLDPE, m-PE, ethylene / vinyl acetate copolymer, polypropylene homopolymers or copolymers, Polyester homo- or copolymers or mixtures with or from the polymers mentioned, and the same or different structure and / or are composed. Sealing strip according to one of claims 1 to 4, characterized in that at least one side between the pressure-sensitive adhesive layer and sealing layer a (tear-resistant) carrier layer is provided which is a bi- or monoaxially oriented film of polypropylene (PP), polyethylene terephthalate (PET) or polyamide (PA) or from mixtures or copolymers formed with or between these polymers. Sealing strip according to one of claims 1 to 5, characterized in that the sealing layer is formed by a multi-layer coextruded film containing on both sides outside a sealing layer and inside at least one functional layer. Sealing strip according to one of claims 1 to 6, characterized in that the pressure-sensitive adhesive layer is thinner than the adjacent sealing layer and has a thickness of 10 to 20 microns, preferably 10 to 15 microns. Sealing strip according to one of claims 1 to 7, characterized in that adjoining the pressure-sensitive adhesive layer sealing layers have a thickness of 20 to 50 microns, preferably 20 to 30 microns. Sealing strip according to one of claims 1 to 8, characterized in that the strip more than 100 m, preferably> 1000 m long running roll material is made up with a substantially uniform width of 10 to 20 mm. Sealing strip according to one of claims 1 to 9, characterized in that the strip has a thickness of 50 to 150 microns, wherein the thickness of the pressure-sensitive adhesive layer is less than one third of the total thickness and the internal pressure-sensitive adhesive layer by at least a quarter of Total thickness is spaced from the surfaces of the sealing strip. Use of the sealing strip according to one of claims 1 to 10 for the production of a resealable foil packaging. Film packaging, in particular film tube bag, with at least one sealed seam, which is provided for opening and re-closing of the packaging and in which in the sealed seam along the sealing direction a film strip provided on both sides with a sealing layer is sealed, which has a pressure-sensitive adhesive layer between its sealing layers, characterized in that the foil strip is a sealing strip according to one of claims 1 to 10. A method for producing a film tube bag which can be resealed after opening a seam provided for this purpose, wherein the film tube bag is produced in a manner known per se, characterized in that in the sealing of at least one sealed seam provided for opening and reclosing the package, a sealing strip according to one of claims 1 to 10 is inserted. A method according to claim 13, characterized in that the film tube bag is made in a continuous process of at least one run of a roll of film web and the sealing strip is fed from a separate roll or spool of continuously at the speed of the film web or runs off the reel or spool , A method according to claim 13 or 14, characterized in that the envisaged for opening and reclosing seal seam is a fin seam. Method according to claim 13 or 14, characterized in that the sealing seam provided for opening and reclosing is an a / b seam with overhang. A method according to claim 13 or 14, characterized in that the seam provided for opening and reclosing is a blind seam.

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