EP4053030A1 - Tubular body for forming a packaging and packaging therewith - Google Patents

Abstract

The cellulose-based packaging (1) comprises a tubular body (2) obtained by welding or gluing a sheet. It comprises at least one longitudinal weld (3) connecting the ends of said sheet, at least one internal welding strip (11) located inside the packaging to form said longitudinal weld (3), the internal strip (11 ) comprising a sealing material which becomes liquid during the welding of the ends and fills the cavities (13) formed at the ends of the internal band (11) so that the packaging is sealed once welded.

Description

TECHNICAL AREA

The invention lies in the field of recyclable packaging comprising welding or gluing operations in their manufacturing process. More specifically, the invention relates to cellulose-based packaging comprising a tubular body obtained by welding or gluing a sheet. The invention applies to the field of packaging and in particular that of flexible tubes intended to contain products such as creams or pastes; or the field of cans to contain liquids replacing aluminum; or even the field of bottles for cosmetic products.

STATE OF THE ART

The patent EP1260447B1 from Otani describes paper pulp packaging made by molding. The Otani patent has many advantages because it makes it possible to obtain packaging with a high cellulose content. The method according to Otani makes it possible in particular to form packages with threads having a high resistance and durability. However, the process for obtaining these packages has a long cycle time, which does not allow high-speed production at a competitive cost. In addition, the method does not allow the thickness of the packaging to be modulated locally, which is penalizing when it is desired to produce flexible packaging such as tubes for example.

Plastic or metal-plastic or paper-plastic tubes made by welding a tubular body onto a tube head, such as flexible tubes, are for example described in the publications FR2505250 , GB1118632 , US2119926 and US4132331 . The issue of leakage at the intersection of welds is not addressed in these documents because the tubes described in these publications have a majority of plastic or synthetic material which melts at least partially or totally during the welding operation and prevents the formation of cavities. However, the prior art does not teach us how to obtain airtight packaging when materials based on cellulose or other equivalent materials (natural or synthetic) which do not melt under the effect of temperature are mainly used.

The invention makes it possible to remedy the aforementioned problems and to produce leaktight packaging which meets the requirements of the market.

The figures 1 and 2 illustrate the problem to be solved for the manufacture of cellulose-based packaging based on the teachings of the prior art.

In the prior art, the cavity 16 is filled by welding operations which cause the plastic material present in the tubular body 2 and/or in the component 8 (such as a tube head) to flow under the effect of temperature and pressure. Thus, the tightness of the package can be realized.

With structures based on cellulose or other equivalent materials which do not melt during welding (or in any case which do not flow during heating and/or compression), it becomes difficult, if not impossible, to fill the cavity 16 during the welding operation due to the reduced quantity of material capable of flowing and the packaging which results therefrom is therefore not perfectly sealed against liquids or gases since the cavity 16 of the figures 1 and 2 remains present.

SUMMARY AND PRINCIPLE OF THE INVENTION

The invention overcomes the aforementioned drawbacks and allows the manufacture of a wide variety of cellulose-based packaging by welding at least one cellulose-based sheet and a component such as a head tube or bottom. The invention makes it possible to produce, at a high production rate and at a competitive cost, packaging having a high quantity of cellulose or of material directly resulting from the paper or cardboard industry. Consequently, the packaging produced according to the invention can be easily recycled in the paper industry, unlike the packaging of the state of the art containing a majority of plastic or synthetic material.

The invention relates more specifically to packaging comprising a tubular body obtained by welding or gluing a cellulose-based sheet and by welding or gluing at least one cellulose-based component.

More generally, the invention can be used for making packaging with materials which mostly remain solid during the welding operation and consequently cannot creep under the effect of temperature and pressure.

Another advantage of the invention is to make it possible to obtain easily recyclable packaging because the percentage of material added to allow welding is significantly reduced. The majority of the material forming the packaging is therefore recyclable in a conventional sector.

The invention allows for example the manufacture of flexible packaging such as tubes for liquid, viscous or pasty and/or solid products (such as creams, pastes, liquids or cosmetic products), or the manufacture of packaging for liquid products such as bottles or cans, or even the making of packaging for dry products such as, for example, coffee, powdered milk, or even powdered chocolate.

An advantage of the invention is to reduce the quantity of plastic or synthetic material constituting the packaging while avoiding the leaks which usually appear when the quantity of synthetic material or material plastic becomes too reduced. The invention makes it possible to solve the problem of leaks in sealed packaging containing a high level of cellulose, the leak being mainly located at the intersection of two welds, for example in the case of a tube, the longitudinal weld of the tubular body and the transverse welding of the tube head to the tubular body.

• La fuite solide : produit sous forme de poudre qui s'échappe de l'emballage (grosse fuite)
• La fuite liquide : produit liquide qui s'échappe de l'emballage (fuite moyenne)
• La fuite gazeuse : gaz qui s'échappe de l'emballage ou gaz qui entre dans l'emballage (petite fuite). Pour les emballages nécessitant des propriétés barrières à l'oxygène, les micros-fuites sont pénalisantes car elles réduisent considérablement la durée de conservation du produit emballé.

In the description of the invention, the term leakage designates, depending on the context and the desired preservation properties:

• Solid leak: product in the form of powder that escapes from the packaging (big leak)
• Liquid leak: liquid product that escapes from the packaging (average leak)
• The gaseous leak: gas which escapes from the packaging or gas which enters the packaging (small leak). For packaging requiring oxygen barrier properties, micro-leaks are penalizing because they considerably reduce the shelf life of the packaged product.

An object of the invention is in particular to propose a method and a product making it possible to avoid these leaks and these micro-leaks which are difficult to measure during production.

The packages produced according to the invention comprise a tubular body formed by welding or gluing a sheet, for example of cellulose or of another equivalent material which does not flow during this welding and/or gluing operation. This so-called longitudinal welding of the tubular body comprises an internal welding strip and an external welding strip connecting the ends of the cellulose sheet positioned end to end. These internal and external welding strips are necessary due to the composition of the sheet forming the tubular body, namely essentially cellulose, for example in one embodiment.

The invention notably comprises the characteristic of at least partially filling the cavities which form at the intersection of the welds with material originating from the internal strip. Under the effect of temperature and pressure during welding, this material becomes liquid and, by flow, fills the cavities, making the packaging airtight and therefore eliminating the undesirable leaks mentioned above.

According to the invention, the inner strip comprises at least one sealing layer consisting of material which becomes liquid during the welding step and fills the cavities. According to the invention, the sealing layer represents at least 1% of the volume of the internal strip, and preferably at least 5% of the volume of the strip.

According to a preferred embodiment of the invention, in the inner band, only the sealing material which can also be a welding material becomes liquid during welding.

According to one embodiment, the internal band comprises a second layer which does not melt during the welding operation and confers a high resistance to the weld. This layer is for example based on very resistant paper, or based on bi-oriented PET or based on bi-oriented PP.

According to other embodiments, the internal band can comprise sealing material, a second layer as described above and one or more other additional layers of the same composition or not.

According to a variant of the invention, the internal band consists solely of sealing material.

Other variants and embodiments of the invention are described below.

In embodiments, the invention relates to a tubular body for packaging intended to contain products in liquid, viscous or solid form. The tubular body comprises a sheet based on a material which does not flow or flows very little during its welding and at least one first longitudinal weld connecting the ends of said sheet to form said tubular body. The tubular body comprises at least one internal welding strip located inside the body to form said longitudinal weld, said internal strip comprising a sealing material which becomes liquid during the welding of the ends of the sheet and which is intended to fill cavities formed at the ends of the inner band in order to make the packaging airtight.

In embodiments, the sheet is cellulose-based.

In embodiments, the tubular body comprises at least a second weld and an intersection zone between said second weld and said first weld, said cavities being formed in the intersection zone by said internal welding strip and filled by the sealing material.

In embodiments, the second solder connects the sheet to a component.

In embodiments, the component can be a tube head, or a neck, and/or a bottom for example.

In embodiments, the second weld is an end weld of the tubular body, the end weld being preceded or not by a bend at around 180° to increase the pressure resistance of the second weld.

In embodiments, the sealing material preferably represents at least 1% of the volume of the internal band.

In some embodiments, the sealing material can be formed from PE, or from PP, be wax-based or from another resin, or even from an adhesive.

In embodiments, the inner strip may comprise a second layer which does not become liquid during the welding operation and which provides high resistance to the weld.

In embodiments, the second layer can be based on paper, or bi-oriented PET or bi-oriented PP.

In embodiments, the internal strip has a width preferably equal to or greater than 2 mm.

In embodiments, the internal strip has a thickness preferably equal to or less than 100 microns.

In embodiments, the body may include an outer seal strip located outside the package.

In embodiments, the outer strip preferably has a width equal to or greater than 2 mm and/or a thickness equal to or less than 300 microns.

In embodiments, the present invention relates to a packaging comprising at least one tubular body as described in the present application.

BRIEF DESCRIPTION OF THE DRAWINGS

• The figures 1 and 2 illustrate the problem to be solved linked to the manufacture by welding of a cellulose-based packaging.
• The figure 1 illustrates the sectional view of the end weld of a tubular body according to the knowledge of the prior art. In particular, the formation of the cavity 13 is observed, which does not make it possible to obtain leaktight packaging.
• The picture 2 illustrates the sectional view of the weld of a tubular body on a component according to the knowledge of the prior art. Here too, the formation of the cavity 13 is observed, which does not make it possible to obtain leaktight packaging.
• The picture 3 illustrates an example of packaging produced according to the invention. The picture 3 represents the two opposite sides A and B of a cellulose-based tube.
• The figure 4 illustrates the CC section of the tube shown in the figure 1 . Section CC makes it possible to observe the end weld of the tubular body. This figure shows how the invention solves the problem of leakage at the intersection of the longitudinal weld and the end weld.
• The figure 5 illustrates the DD section of the tube shown in the figure 1 . The DD section makes it possible to observe the weld between the tubular body and the component. This figure shows how the invention makes it possible to solve the problem of leakage at the intersection of the longitudinal weld and the weld of the component.
• The figure 6 more precisely illustrates the intersection area between the longitudinal weld and the component weld.
• The figure 7 illustrates an optional configuration of the end closure having an end weld and a ply located upstream of said weld.
• The figure 8 illustrates a detailed view of the optional configuration of the figure 7 .
• The figure 9 illustrates a packaging produced according to the invention in the form of a can. This packaging has two components welded to a tubular body.
• The figure 10 illustrates a bottle made according to the invention and comprising two components welded to a tubular body.
• The figure 11 illustrates a welding configuration of the tubular body on the component in which the diameter of the tubular body is reduced in the welding zone.
• The figure 12 and 13 illustrate variants of the invention for other longitudinal weld configurations.

The figure 14 illustrates a tetrahedron-like wrapper with two end closures.

The figure 15 illustrates a brick-type package including two end closures and folding operations.

DETAILED DESCRIPTION

• 1: cellulose-based packaging
• 2: tubular body
• 3: longitudinal weld
• 4: end weld
• 5: component solder
• 6: zone of intersection of the longitudinal weld and the end weld
• 7: intersection area of longitudinal weld and component weld
• 8: component, for example as a tube head
• 9: cellulose-based layer of the tubular body
• 10: sealing layer of the tubular body
• 11: internal welding strip
• 12: outer welding strip
• 13: cavities
• 14: inside the packaging
• 15: ply of the tubular body
• 16: cavity not sealed

The invention relates in particular to packaging based on cellulose (or based on another equivalent material) and manufactured by welding or gluing. In the following description of the invention, the term welding is used to describe assembly by welding or by gluing.

The packaging according to the invention comprises at least one tubular body obtained by welding a sheet, for example based on cellulose; and at least one component, for example based on cellulose, welded to the end of the tubular body.

The packaging comprises at least a first so-called longitudinal seam which results from the manufacture of the tubular body from a cellulose-based sheet. The longitudinal weld is parallel to the axis of the tubular body.

The packaging also comprises a second weld which connects the end of the tubular body to a component, said component being for example a head with an orifice for extracting the product or for example a bottom. The welding of the end of the tubular body to the component intersects the longitudinal weld, for example perpendicularly.

The picture 3 illustrates an embodiment of the invention. The picture 3 represents the two opposite faces A and B of a flexible tube manufactured according to the invention. This tube comprises a tubular body 2 formed from a sheet based on cellulose and whose ends are welded. We observe on the face B of the tube 1 the longitudinal weld 3 connecting the ends of said sheet. The longitudinal weld 3 normally extends over the entire length of the tubular body 2.

The tube illustrated in the picture 3 comprises a second weld 5 which binds the end of the tubular body 2 to a component 8 also based on cellulose. The intersection between the longitudinal weld 3 and the weld of the component 5 forms a first intersection zone 7 and the principle of the invention makes it possible to seal the first intersection zone 7.

The tube illustrated in the picture 3 comprises a third so-called end weld 4 which closes the second end of the tubular body 2 by flattening and welding illustrated in figure 4 . The intersection between the longitudinal weld 3 and the end weld 4 forms a second intersection zone 6 and the principle of the invention makes it possible to seal the second intersection zone 6. According to the invention, the packaging can also comprise two end welds 4 in one embodiment.

According to the invention, the packaging consists mainly of cellulose, that is to say of compositions commonly used in the paper industry. These compositions generally comprise a majority of cellulose (for example 70% or more), mineral fillers (for example calcium carbonate or kaolin), dyes or optical brighteners, binders (for example starch or latex ), and possibly lignin. According to the invention, the packaging may also comprise fine barrier layers such as for example against humidity or oxygen. These layers can be made of thermoplastic resins such as for example PE, PP EVOH, PVOH, PLA or thin layers such as SiOx layers or metallized layers or even coatings or nanocoatings. Other materials equivalent to cellulose are of course possible and envisaged within the scope of the present invention.

The figure 4 illustrates the CC section of the packaging shown picture 3 . Section CC makes it possible to observe the end weld 4 of the tubular body 2. The end weld 4 intersects the longitudinal weld 3 in the zone 6. According to the invention, the longitudinal weld 3 is produced by edge to edge welding ends of the sheet via at least a first internal sealing strip 11 located inside the packaging and a second external sealing strip 12 located outside the packaging. The internal strip 11 is trapped in the end weld 4 at the level of the zone 6 of intersection between the end weld 4 and the longitudinal weld 3.

On the figure 4 , due to the intersection of these two welds 3 and 4, the presence of cavities 13 is observed at the ends of the internal welding strip 11. These cavities are formed in particular by the penetration of the strip into the compressible walls of the body tubular under the effect of welding pressure. Cellulose-based structures like paper are generally compressible.

As can be observed on the figure 4 , an advantage of the invention is linked to the fact that the size of the cavities 13 is no longer linked to the thickness of the wall of the tubular body as illustrated figures 1 and 2 ; but is directly linked to the thickness of the internal strip 11. By using a thin internal strip, the invention makes it possible to significantly reduce the size of the cavities 13 and consequently the addition of sealing material necessary to fill said cavities 13 is also significantly reduced.

According to the invention, the thickness of the internal strip 11 is less than half the thickness of the wall of the tubular body 2 and preferably less than 1/3 of said thickness. According to embodiments of the invention, the thickness of the internal strip 11 is approximately equal to or less than 100 microns and preferably less than 60 microns and the width of the internal strip 11 is approximately equal to or greater than 2 mm and preferably greater than 3mm. According to other embodiments of the invention, the thickness of the strip internal 11 is equal to 30 microns and its width is equal to 4 mm. For the outer strip 12, according to embodiments, its width is preferably approximately equal to or greater than 2 mm. According to embodiments, the thickness of the outer strip 12 is approximately equal to or less than 300 microns, preferably less than 100 microns. Of course, these values are indicative for illustrative examples and other values are possible depending on the circumstances, for example.

According to the invention, the cavities 13 which form at the ends of the internal strip 11 in the zones 6 and/or 7 are filled at least in part, and preferably completely, with a sealing material originating from said internal strip 11 This sealing material, under the effect of the temperature and the pressure during the manufacture of the packaging, becomes liquid and by flow fills the cavities 13, making the packaging leaktight.

According to the invention, the inner strip 11 comprises at least one sealing layer consisting of material which becomes liquid during the welding step and fills the cavities 13. According to the invention, the sealing layer represents at least 1% of the volume of the inner band 11, and preferably at least 5% of the volume of the inner band 11.

According to a preferred embodiment of the invention, in the inner strip 11, only the sealing material which is also a welding material becomes liquid during welding.

According to another embodiment, the internal band 11 comprises a second layer which does not become liquid during the welding operation and confers a high resistance to the weld. This second layer is for example based on very resistant paper, or based on bi-oriented PET or based on bi-oriented PP.

According to a variant of the invention, the inner strip 11 only comprises sealing material.

The sealing material is for example made of PE or PP or based on Wax or another resin which changes from the solid state to the liquid state under the effect of the welding temperature. The sealing material can also be an adhesive. Other equivalent materials are possible and contemplated within the scope of the present invention.

On the figure 4 , the cellulose-based layer 9 of the tubular body preferably also comprises a barrier layer which is not shown (for simplicity) and which provides the desired properties both in terms of the barrier to moisture or the barrier to oxygen or aromas. The position and number of these barrier layers in the structure of the tubular body 2 depends on the desired properties. Preferably for reasons of recyclability, very thin functional barrier layers such as Siox layers, metallized layers, coatings or nano-coating are used. Alternatively barrier layers made of thermoplastic polymer such as for example EVOH, PVOH, PVDC, PE, PP can be used. These are of course non-limiting examples.

On the figure 4 , the layer 10 represents the sealing layer of the tubular body which covers the internal surface of the tubular body. To allow recycling of the packaging, this sealing layer is thin. Preferably, the sealing layer 10 is a sealing varnish or a thin layer having equivalent weldability properties. Alternatively, the layer is made of thermoplastic resin such as, for example, polyethylene or polypropylene. These are of course non-limiting examples.

The figure 5 illustrates another example of the invention when the tubular body 2 based on cellulose is welded to a component 8 such as a tube head. The principle of the invention makes it possible to solve the problem of sealing of the assembly at the intersection between the weld 5 of the component and the longitudinal weld 3 of the tubular body.

The figure 5 illustrates the DD section of the package shown picture 3 . The section DD makes it possible to observe the weld 5 of the tubular body 2 on the component 8 and in particular the zone of intersection 7 between the weld of the component 5 and the longitudinal weld of the tubular body. According to one embodiment of the invention, the longitudinal weld is made by edge to edge welding of the ends of the sheet 9 via at least one internal welding strip 11 located inside the packaging. and an outer sealing strip 12 located outside the package. The internal strip 11 is trapped in the solder of the component at the level of the zone 7 of intersection of the solder of the component 5 and of the longitudinal solder 3.

On the figure 5 , the cavities 13 are observed at the ends of the internal welding strip 11. These cavities are formed in particular because of the depression of the internal welding strip 11 in the compressible walls of the tubular body 2 under the effect of the pressure of welding.

According to the principle of the invention, the cavities 13 are filled at least in part, preferably totally, with sealing material coming from said internal strip 11. Under the effect of temperature and pressure, this sealing material becomes liquid and by flow fills the cavities 13, making the packaging airtight at the level of the intersection zone 7.

The figure 6 illustrates a detail of the intersection zone 7 between the weld 5 of the component and the longitudinal weld 3. The figure 6 makes it possible to better understand the interest of the invention in obtaining easily recyclable packaging because the thickness of the sealing layers 10 can be significantly reduced. Indeed, the invention makes it possible to reduce the thickness of the sealing layers 10 thanks to the local supply of a surplus of sealing material via the internal strip 11 which makes it possible to fill the cavities 13. The local supply of sealing material which can also be sealing makes it possible to guarantee the properties of impermeability of the packaging to liquids as well as to gases.

The invention makes it possible to use thin functional layers of very thin thickness both for the barrier layers and for the sealing layers 10. The invention therefore has a great advantage for the production of recycled packaging based on cellulose.

The invention also allows the production of single-material recyclable plastic packaging with thin functional layers (micro or nano-layers). This packaging is advantageous because it is easily recyclable. However, their manufacture by welding is often difficult because of the difficulty of obtaining leaktight packaging. For example, the manufacture of HDPE tubes with very viscous grades is desired in order to be able to recycle these tubes in the HDPE flask and bottle sector. The use of these viscous grades makes the welding operation more difficult because these new grades have a higher melting temperature and a much lower fluidity. As a result, leakage problems from these packages occur at the weld intersection as detailed above. The invention makes it possible to remedy this problem by supplying sealing material via the internal band 11. This caulking material added in negligible quantity has a high melt index and good sealing properties. For HDPE packaging, a high flow PE resin sealant can be used. Of course, other equivalent materials can be envisaged.

In the figure 6 , a butt welding of the sheet forming the tubular body 2 has been shown, but this illustration is only a limiting example and it is possible to use other shapes: for example, the ends of the sheet can be have complementary slopes, bevel, overlap, have other complementary shapes etc. Moreover, the inner band 11 is shown recessed in the tube head 8 and in the body 2, but it could be recessed entirely in the head or in the body or essentially in one or the other. All configurations are possible, also with the outer band 12.

The figure 7 illustrates another aspect of the invention for improving the strength of the end closure of a tube. The figure 7 illustrates a flexible tube 1 comprising a tubular body 2 connected to a tube head 8 and with an end closure comprising an end weld 4 and a fold 15 located outside the end weld 4 and before that -this. Cellulose-based packaging was observed to have lower strength at the end seal due to cohesive failure of the cellulose-based layer under the bursting stress of packaging. It has been demonstrated that by forming a fold 15 of the tubular body 2 before the final weld 4 makes it possible to make the packaging much more resistant.

The figure 8 illustrates the closure weld of tube 1 of the figure 7 in more detail. The tubular body 2 comprises an end weld 4 made according to the principle of the invention. The welded end of the tube is then folded over to form the bend 15 at approximately 180° (for example) before and outside the end weld 4, this construction having the effect of increasing the pressure resistance of the weld. end. In order to maintain the folded end piece in position, numerous variants are possible. For example, the folded end piece can be glued or welded against the wall of the packaging. An alternative is to use a self-adhesive label to hold the bent tube end against the wall of the tubular body 2. When the pressure increases inside the packaging, for example due to the effect of the pressure exerted to extract the product of the packaging, the fold 15 avoids the stress on the welded zone 4 and thus increases the resistance of the end closure.

The figures 9 and 10 illustrate other examples of packaging made according to the invention.

The figure 9 represents a cellulose-based packaging of the "can" type and intended to contain products such as liquids or powders. This packaging of cylindrical geometry, easily stackable, comprises a tubular body 2 with a longitudinal weld 3 as well as two components 8 fixed respectively at each end by means of a weld 5. The zones 7 of intersection of the welds 3 and 5 are sealed against liquids and gases thanks to the principle of the invention as described in the present application. The “can” type packaging comprises a first component 8 forming the bottom of the packaging, and a second component 8 comprising means for extracting the product from the packaging; said means possibly being an orifice closed by a lid, or a device for easy opening by tearing off material in order to create an orifice or any other means ensuring the function of opening the packaging.

The figure 10 illustrates a bottle made using the principles of the invention. This bottle comprises a tubular body 2 with a longitudinal weld 3. Components 8 (for example a head or a neck and a bottom) are fixed to each end of the tubular body 2 via welds 5. The intersection of the welds 3 and 5 is sealed by making the packaging according to the principle of the invention.

In other embodiments, the packaging may comprise at each end of the tubular body 2 an end weld 4 as illustrated in figure 7 and 8 (instead of the tube head 8 of the figure 7 ).

The invention makes it possible to produce recyclable packaging based on cellulose. The packaging produced according to the invention comprises a content of paper or similar material greater than 50% and preferably greater than 85% and ideally greater than 95%.

The invention makes it possible to produce recyclable packaging based on single-material plastic and in particular with grades of viscous HDPE. According to the invention, packaging based on HDPE with a melt index of less than 1 (ASTM D1238 standard) and preferably less than 0.5 can be used.

The figure 11 illustrates another aspect of the invention when the diameter of the tubular body 2 is reduced in the welding zone. This is particularly the case when the end of the tubular body 2 is welded to a surface of the conical, toroidal or spherical type. In this case, the reduction in diameter can lead to the formation of folds in the tubular body 2 in the welding zone. When the tubular body 2 has a welding layer of thin thickness, these folds form cavities which generate leaks from the packaging. As these folds form additional cavities randomly distributed around the periphery of the weld 5 between the tubular body 2 and the component 8, these cavities cannot be filled by the sealing material from the internal band 11. It has been found that the The use of a tubular body based on cellulose and deformable in the solid state of at least 3% and preferably of at least 6% makes it possible to avoid the formation of wrinkles during the reduction of the diameter. Thus, the use of tubular bodies in formable paper having a deformation rate of at least 3% is advantageously used to produce packaging with the type of welding illustrated in the figure 11 .

The figure 11 illustrates the welding of a tubular body 2 to a tube head 8. The weld zone 5 forming a toroidal type surface, the diameter of the tubular body is therefore reduced in this zone. As can be observed on the figure 11 , the diameter of the tubular body 2 is most greatly reduced at its end. The tubular body 2 in the weld zone 5 represented on the figure 11 does not present folds because its % deformation is greater than 3% and preferably greater than 6%.

The figure 12 and 13 illustrate variants of the invention for other longitudinal weld configurations.

The figure 12 illustrates the end weld 4 of a tubular body 2 whose longitudinal weld 3 is made by overlapping. The inner strip 11 covers the cavity 16 formed at the overlap, and the cavities 13 formed at the end of the strip 11 are filled with sealing material from the strip. According to a variant of the invention, the cavity 16 is at least partially filled with the sealing material coming from the strip.

The figure 13 illustrates the end weld 4 of a tubular body 2, the longitudinal weld 3 of which is made by welding the internal face to itself. The inner strip 11 covers the cavity 16 formed at the junction of the so-called "triple point" welds, and the cavities 13 formed at the end of the strip 11 are filled with sealing material from the strip. According to a variant of the invention, the cavity 16 is at least partially filled with the sealing material coming from the strip.

The figure 14 illustrates a tetrahedral-type package made according to the invention. The packaging 1 comprises a tubular body with a longitudinal weld 3. The tubular body is closed at the ends by two welds 4 oriented perpendicularly and leading to the tetrahedron geometry of the packaging. Sealing at the intersection 6 of the longitudinal 3 and end 4 welds is achieved by the sealing material of the welding strip.

The figure 15 illustrates a brick-like package formed by welding and bending. The packaging 1 is formed of a tubular body with a longitudinal weld 3. The tubular body is closed by the end welds 4 and then shaped by folding operations and possibly gluing. Thanks to the invention, the packaging 1 comprises a high cellulose content while guaranteeing tightness of the packaging to liquids and gases, in particular at the level of the zones 6 of intersection of the longitudinal weld and the end welds according to the principles of the present invention.

The embodiments described in the present application are by way of illustrative examples and should not be considered as limiting. Other embodiments may make use of means equivalent to those described for example. The modes of execution can also be combined with each other depending on the circumstances, or means used in one mode can be used in another mode.

Claims (15)

Tubular body (2) for packaging (1) intended to contain products in liquid, viscous or solid form, said tubular body (2) comprising a sheet (9) based on a material which does not flow or flows very little during of its weld and at least a first longitudinal weld (3) connecting the ends of said sheet to form said tubular body (2), said tubular body comprising at least one internal welding strip (11) located inside the body to forming said longitudinal weld (3), said internal strip (11) comprising a sealing material which becomes liquid during the welding of the ends of the sheet (9) and which is intended to fill cavities (13) formed at the ends of the strip internal (11) in order to seal the packaging. A tubular body (2) according to claim 1, wherein said sheet (9) is based on cellulose. Tubular body (2) according to claim 1 or 2, said tubular body comprising at least one second weld (4,5), said tubular body comprising an intersection zone (6,7) between said second weld and said first weld ( 3), said cavities (13) being formed in the intersection zone (7) by said internal welding strip (11) and filled with the sealing material. Tubular body according to claim 3, wherein said second weld (5) connects the sheet (9) to a component (8). Tubular body according to the preceding claim, in which the component (8) is a tube head, or a neck, and/or a bottom. A tubular body according to claim 3, wherein said second weld is an end weld (4) of the tubular body (2), said weld end being preceded or not by a bend at approximately 180° to increase the pressure resistance of the second weld. Tubular body according to one of the preceding claims, in which the sealing material represents at least 1% of the volume of the internal band (11). Tubular body according to one of the preceding claims, in which the sealing material is made of PE or PP, is based on wax or another resin, or else on an adhesive. Tubular body according to one of the preceding claims, in which the internal strip (11) comprises a second layer which does not become liquid during the welding operation and which confers a high resistance to the weld. Tubular body according to the preceding claim, in which the said second layer is based on paper, or bi-oriented PET or bi-oriented PP. Tubular body according to one of the preceding claims, in which the internal strip has a width equal to or greater than 2mm. Tubular body according to one of the preceding claims, in which the internal band has a thickness equal to or less than 100 microns. Tubular body according to one of the preceding claims, said body comprising an external sealing strip (12) located outside the packaging. Tubular body according to the preceding claim, in which the outer band has a width equal to or greater than 2 mm and/or a thickness equal to or less than 300 microns. Packaging comprising at least one tubular body according to one of the preceding claims.

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