FR2771718A1 - Sachet packaging film primarily for foodstuffs - Google Patents

Abstract

A packaging material comprising a film which is folded and sealed, to form a sachet, has a rupture line (4) or a thinner line zone along the sachet opening. The rupture line has a width of 0.5-2.0 mm. The rupture line (4) is located at a short gap from the sealing (1), and can be a recessed line with a depth of one-third to two-thirds of the film thickness. The film is closed as a tube and sealed at the inner surfaces of the lateral strips. The rupture line (4) is at right angles to the sealing zone, and opens into the overlap of the film. The rupture line (4) can extend to the center of the sealing zone or as far as the opening notch at one of the package edges. The package can have a second and parallel rupture line, forming a tear-off strip between them. An opening notch can be at one of the package edges, as an extension of the rupture line (4). An Independent claim is included for a production process, where the film thickness is reduced to form the rupture line (4). Preferred Features: The film material is thinned, to form the rupture line, by a heated non-cutting die to melt the film, at a temperature equal to the sealing temperature and at the sealing pressure. The non-cutting die can be activated by ultrasound. The sealed tube can be given the weakened rupture line by the sealing pincers.

Description

PACKAGING, ESPECIALLY BAG, A
EASY OPENING, MANUFACTURING METHOD AND
INSTALLATION FOR IMPLEMENTING SAID PROCESS.

 The present invention relates to packages formed by a film folded and sealed to form a sachet.

 These packages are very commonly used in the packaging of food products, as well as in a large number of other fields.

 They are generally made by sealing a plastic film. To facilitate the opening of these packages, various solutions have been proposed in the prior art.

 A first solution consists in providing a breakout initiator in the sealing zone. In this area, the two thicknesses of the film are superimposed and heat sealed. The rupture initiator normally provides a preferred direction of rupture of the film, and should allow for the rectilinear tearing of the film behind this rupture initiator. It appears in use that this solution is not completely satisfactory because if the traction is exerted at an angle, the tear is not carried out correctly.

 Another solution is to carry out microperforations along the tear line. This solution is of course not suitable for airtight packaging.

 Yet another solution is to glue a tear strip along the tear line. This solution is relatively expensive and is only possible with rectangular packages, but not for sachets.

 To remedy the drawbacks of the prior art, the invention relates to a packaging being provided with means for facilitating the opening formed by a breaking line where the film has a reduced thickness, said zone extending substantially along the opening area and having a width of between 0.5 and 2 millimeters.

 This rupture line gives a preferred path for the tearing of the film, and makes it possible to achieve a clean opening by exerting a traction and a shearing force on either side of this line.

 According to a preferred embodiment, the rupture line is disposed at a short distance from a sealing zone, of the order of a few millimeters.

 According to an alternative embodiment, the package has two substantially parallel breaking lines, delimiting between them a tear strip. A rupture leader provided in the extension of each of the rupture lines, at the edge of the package.

 The sealing area is significantly more resistant than the rest of the sachet, which facilitates gripping and the exercise of traction to cause partial and clean opening. In addition, the remaining sealing zone allows the open part to be folded in while keeping the lips of the opening edge to edge, which will allow easier reclosing than with sachets fully open. Existing closure systems: adhesive label and other solutions, which can only be applied to sachets that are not torn during opening, they are only installed today on unsealed sachets.

 Advantageously, the rupture line is formed by a groove whose depth is between 1/3 and 2/3 of the thickness of the film.

 According to a particular implementation variant, the film is closed in the form of a tube by sealing the inner face of a side strip on the inside face of the opposite side strip, the rupture line extending perpendicular to the area. sealing and starting on the side of the covering part of the film.

 According to a particular embodiment, the rupture line extends to the central sealing zone. The position of the sealing edge determines the length of the opening.

 The invention also relates to a method of manufacturing a packaging consisting of a folded and sealed film, characterized in that a rupture line is produced on the film by weakening the thickness.

 According to a first variant of implementation, the weakening of the film for the formation of the rupture line is carried out by creep of the material using a heated non-cutting matrix.

 Advantageously, the matrix includes a pulse heating resistor heating the matrix to a temperature substantially equal to the nominal sealing temperature, the matrix being applied against the film with a pressure equivalent to the nominal sealing pressure.

 According to a second implementation variant, the weakening of the film for the formation of the breaking line is carried out by creep of the material using a non-sharp matrix excited by a source of ultrasound.

 The invention also relates to an installation for manufacturing sachet-shaped packaging, of the type comprising means for feeding with a film, shaping means for giving the film a tubular shape and sealing pliers capable of being applied. on the film leaving the former, characterized in that it further comprises weakening means for producing at least one breaking line by weakening the thickness of the film.

 Advantageously, the weakening means are provided on the sealing pliers.

The invention will be better understood on reading the description which follows, referring to the accompanying drawings in which:
- Figure 1 shows a front view of a bag according to a first embodiment of the invention;
- Figure 2 shows a view along a section plane AA ';
- Figure 3 shows a view along a section plane AA ', for an embodiment using thick films
- Figure 4 shows a view along a section plane BB ';
- Figure 5 shows a view of the film before it is shaped
- Figure 6 shows a front view of a bag according to a second embodiment of the invention;
- Figures 7 to 9 show front view of sachets according to other embodiments of the invention.

 FIG. 1 represents a nonlimiting example of a first exemplary embodiment.

 The sachet is formed from a film of simple or composite plastic material, for example extruded polyethylene or polypropylene. I1 is folded back to form a tube closed at both ends by sealed areas (1, 2). The two lateral strips of the film overlap, inside face against inside face, to form a longitudinal sealing edge (3). The film has a rupture zone (4) extending 4 millimeters from the inner edge of the sealed zone (1), up to the sealing edge (3).

 This rupture line has a width of the order of 0.8 millimeters. It corresponds to a groove formed in the thickness of the film, over about half of the thickness of the film.

 Figure 2 shows a view along a section plane AA '. The film is sealed at its ends by heat welding or by ultrasound, in a manner known in the prior art. The sealing area (1) extends over a few millimeters. The film has a groove (4) which can be produced on the internal face or on the external face. The groove (4) is separated from the sealing area (1) by an area (5) with a width of a few millimeters. The groove (4) is formed using a non-cutting die heated by impulse to the nominal sealing temperature of the film, or excited by ultrasound, or by any other solution continuously regulating the temperature to have the deformation of the film at the chosen location without modification of the rest of the strip. The material composing the film slightly creeps at the breaking line (1), and a molecular rearrangement takes place which modifies the resistance of the film at this line.

 FIG. 3 shows a view along a section plane AA ′, for an embodiment using thick films. In this case, a second groove (6) is made in the bottom of the first groove (7). The radius of curvature of the second groove (6) is less than the radius of curvature of the first groove (7).

 Figure 4 shows a view along a section plane BB '. The connection zone of the two lateral ends of the film forms a sealing edge (3) having a double thickness. The internal face (8) of the covering part (9) of the film is assembled by heat sealing with the internal face (10) of the covered part (11). The covered part (11) is folded over 1800 to allow the formation of a flat bag.

 The breaking line extends from the side of the covering end (9) so as to avoid reversing the breaking direction. The rupture line (4) extends at least as far as the sealing edge.

 FIG. 5 represents a view of the film before it is shaped. The rupture line (4) extends in a central region, possibly extending to the edge of the covering part (9).

 FIG. 6 represents a front view of a sachet according to a second embodiment of the invention. In this embodiment, the breaking line (13) has a shape in an arc of a circle, so as to form a spout which can be closed by folding the sealed area (1) after use.

 FIG. 7 represents a front view of a sachet according to a third embodiment of the invention. According to an alternative embodiment, the bag has a rupture initiator (20) provided on the edge of the bag, possibly at a sealing zone.

This breaking point (20) is constituted by an incision in the shape of a "V" cut out on the edge of the sachet.

It promotes the start of the tearing along the line of rupture (4) which extends this initiation of rupture (20).

 In the example described in FIG. 8, the rupture line (4) continues on the sealing strip (3). This sealing strip is folded in the direction of traction represented by the arrow "F". This embodiment is suitable for fully opening the sachet.

 If only partial opening is desired, the rupture line (4) is provided on the side opposite to the folding of the sealing strip (3). In this case, the tear "knocks" on the folding, and blocks the continuation of the rectilinear rupture, to cross the sealing zone of closure of the sachet.

 FIG. 9 represents another variant of a sachet constituted by a complex produced with polyester type materials laminated with polypropylene or polyethylene. It is then desirable to have a tear primer to start the rupture of the film.

 The mechanical primer will be made above the seal to pass through it, and come perpendicularly to join the horizontal rupture zone of the PE or PP film.

 This opening primer can also be obtained by embrittlement of the polyester by heating and pressure, in order to obtain the elongation and the deformation of the film, which will reduce the thickness and the mechanical strength of the polyester. During the opening, a shearing of the film will cause a rupture and as in the case described in FIG. 8, it will be possible to obtain a total opening.

 In all cases, once the primer has been made, the polyester no longer has any mechanical resistance. The breaking line obtained will be that of the PE or PP film which can fully play its role of guide. The traction exerted to open will be carried on the weakened part causing the elongation, then the rupture of the plastic film, the polyester following this guidance.

 The invention is described in the foregoing by way of nonlimiting example. It is understood that the skilled person will be able to produce different variants without departing from the scope of the invention.

Claims (14)

R E SELL I CATI ON S  1 - Packaging formed by a folded and sealed film to form a sachet, said packaging being provided with means to facilitate opening, characterized in that said means is formed by a breaking line (4) where the film has a reduced thickness, said line extending substantially along the opening zone and having a width of between 0.5 and 2 millimeters.  2 Packaging according to claim 1 characterized in that the rupture line (4) is arranged a short distance from a sealing area (1).  3 - Packaging according to claim 1 or 2 characterized in that the rupture line (4) is formed by a groove whose depth is between 1/3 and 2/3 of the thickness of the film.  4 - Packaging according to any one of the preceding claims, characterized in that the film is closed in the form of a tube by the sealing of the internal face of a lateral strip on the internal face of the opposite lateral strip, the breaking line ( 4) extending perpendicular to the sealing zone and starting from the side of the covering part of the film.  5 Packaging according to claim 4 characterized in that the rupture line (4) extends to the central sealing area.  6 - Packaging according to any one of the preceding claims, characterized in that the rupture line (4) extends to a rupture initiation provided on one of the edges of the packaging.  7-Packaging according to any one of the preceding claims, characterized in that the package has a second break line substantially parallel to the first break line, the two break lines delimiting between them a tear strip.  8 Packaging according to the preceding claim characterized in that a breaking point is provided in the extension of each of the breaking lines, at the edge of the package.  9 - A method of manufacturing a package consisting of a folded and sealed film, characterized in that a rupture line (4) is produced on the film by weakening the thickness.  10 - A method of manufacturing a packaging according to claim 9, characterized in that the weakening of the film for the formation of the breaking line (4) is carried out by creep of the material using a heated matrix not sharp.  11 - A method of manufacturing a package according to claim 10, characterized in that the matrix comprises a pulse heating resistance heating the matrix to a temperature substantially equal to the nominal sealing temperature, the matrix being applied against the film with a pressure equivalent to the nominal sealing pressure.  12 - A method of manufacturing a packaging according to claim 9, characterized in that the weakening of the film for the formation of the breaking line (4) is achieved by creep of the material using a non-matrix sharp excited by a source of ultrasound.  13 - Installation for the manufacture of packaging in the form of a sachet, of the type comprising means for feeding with a film, shaping means for giving the film a tubular shape and sealing pliers capable of being applied to the outgoing film. the shaper, characterized in that it further comprises weakening means for producing at least one breaking line (4) by weakening the thickness of the film.  14 - Installation for the manufacture of packaging in the form of a bag according to claim l3 characterized in that the weakening means are provided on the sealing clamps.