Heat-sealable paper for product packaging

Abstract

The invention relates to a heat-sealable paper (1) for packaging a product comprising at least one layer of cellulose fibers (2) and at least one layer of hot-melt adhesive (3). According to the invention, the at least one layer of hot-melt adhesive (3) is deposited discontinuously on the layer of cellulose fibers (2) along the entire length and width of the cellulose fiber layer, the hot-melt adhesive layer having a melting point above 80°C. Figure to be published with the abstract: Fig. 1

Description

Title of the invention: Heat-sealing paper for packaging a product Technical field

[0001] The invention relates to the technical field of heat-sealing papers suitable for use in packaging, more particularly the packaging of press copies.

[0002] The invention also relates to a method for manufacturing a heat-sealing paper and a device for implementing said method. State of the art

[0003] It is necessary to package each press copy in a packaging in order to protect the press copies during transport. Generally, the packaging of these press copies is in the form of a film composed mainly of plastic.

[0004] However, in recent years, legislation in many countries has been reducing the use of plastic in all types of industry. Therefore, manufacturers of plastic films for packaging must find an alternative material for packaging in order to maintain its properties, such as low cost and good protection.

[0005] For this purpose, packaging film manufacturers have replaced plastic with packaging made of paper fibers, the latter being glued to a specific location, where the welding for closing the packaging is carried out. However, such a method requires a high degree of adaptability of the machines depending on the differences in the dimensions of the press copies to be packaged. Indeed, sealing the packaging by gluing then requires modifying the packaging devices depending on the dimensions of the press copies.

[0006] Thus, these devices, in order to adapt to the different dimensions, must undergo heavy modifications resulting in a heavy and costly packaging process.

[0007] Alternatively, manufacturers have produced a heat-sealing paper packaging comprising a layer of plastic, generally polyethylene terephthalate known by the acronym "PET", allowing the plastic to be welded. Thus, there is no longer any problem of adaptability of the machines, consequently reducing the cost of the process. However, the use of plastic, even in small quantities, leads to ecological problems.

[0008] Another method consists of a water-based heat-sealing paper made by coating the paper with a cold water-based glue.

[0009] This method requires depositing a layer of aqueous phase glue then to remove all the water present in the aqueous phase glue, said glue being composed of approximately 60% water, in order to leave only pure glue or glue extract. Thus, to leave only the minimum quantity necessary for this process, it is impossible to make this deposit in one go because the quantity of water deposited would be too large and would have the effect of breaking the paper strip.

[0010] Therefore, manufacturers perform several successive water-based adhesive coatings of a smaller quantity. Each of the adhesive coating steps is followed by a heat-drying step to reduce the water-based adhesive during coating. However, such a process is very energy-intensive and expensive.

[0011] The invention therefore falls within this context and seeks to resolve all of the aforementioned drawbacks.

[0012] Thus, the invention seeks to produce a less expensive, ecological heat-sealing paper that is adaptable to different packaging devices, particularly press copies. Presentation of the invention

[0013] The invention relates to a heat-sealing paper that is less expensive, ecological and adaptable to different packaging machines, particularly for press copies.

[0014] An additional object of the invention is a method for manufacturing a rapid and less expensive heat-sealing paper according to the invention, said paper suitable for packaging, in particular press copies.

[0015] Another object of the invention is a device for implementing said method of manufacturing heat-sealing paper according to the invention.

[0016] For this purpose, a heat-sealing paper has been developed for packaging a product comprising at least one layer of cellulose fibers and at least one layer of hot-melt glue.

[0017] According to the invention, the at least one layer of hot-melt glue is deposited on the layer of cellulose fibers, discontinuously over the entire length and width of the layer of cellulose fibers, the layer of hot-melt glue having a melting point at a temperature above 80°C.

[0018] The hot melt adhesive layer does not contain water and is applied hot.

[0019] Thus, a heat-sealing paper is obtained without a layer of plastic material, allowing it to be produced in an ecological and less expensive manner, so that when the paper is exposed to a temperature above 80°C, the layer of hot-melt glue melts and forms a bond with the cellulose fibers to create a rigid and resistant structure.

[0020] In addition, the presence of a layer of hot melt glue makes it possible to eliminate the successive coating and drying steps required when using a cold water-based glue make the process cumbersome and expensive. In fact, using a water-free, hot-applied glue avoids the need to apply several layers of water-based glue.

[0021] In addition, the fact of a layer of heat-activated hot-melt glue makes the heat-sealing paper adaptable to any packaging device, in particular press copies. Indeed, in order to stick the heat-sealing paper to itself to carry out the packaging, it is simply necessary to heat the heat-sealing paper sufficiently to reactivate the hot-melt glue.

[0022] The depositing of the layer of hot-melt glue on the layer of cellulose fibers in a discontinuous manner makes it possible to create a heat-sealing paper comprising a layer of hot-melt glue which is not distributed homogeneously on the layer of cellulose fibers.

[0023] In a particular embodiment, the hot melt adhesive layer comprises a mixture of hot melt resin in contact with the layer of cellulose fibers, such that when the paper is exposed to a temperature above 80°C, the hot melt resin adhesive layer melts and forms a bond with the cellulose fibers and the layer of thermoplastic polymer.

[0024] Preferably, the layer of hot melt adhesive is deposited on the layer of cellulose fibers with a density of 1 to 8 g / m2.

[0025] More preferably, the layer of hot-melt glue is deposited on the layer of cellulose fibers in a single pass.

[0026] The term "density" is intended to define the fact that on a surface of one square meter of cellulose fiber, there are between 1 and 8 grams of hot melt glue.

[0027] Thus, the use of a small quantity of hot-melt glue makes it possible to reduce the manufacturing cost of such paper, while producing a heat-sealing paper whose adhesive strength is sufficient for packaging, in particular press copies.

[0028] In a particular embodiment, the layer of cellulose fibers and the layer of hot-melt glue are arranged so that the deposition of the layer of hot-melt glue on the layer of cellulose fibers forms several deposits of said hot-melt glue on the layer of cellulose fibers, said deposits being interconnected with each other on the layer of cellulose fibers.

[0029] Thus, the surface tension of the hot melt adhesive and that of the layer of cellulose fibers form several deposits of said hot melt adhesive on the layer of cellulose fibers, said deposits remaining connected to each other on the layer of cellulose fibers.

[0030] Thus, the layer of hot-melt glue, due to its surface tension, groups together in points of aggregates linked to the cellulose fibers.

[0031] Indeed, the quantity of hot melt glue is such that the surface tension of the hot melt glue creates a layer of hot melt glue having irregularities of deposition, which creates areas having a lower quantity of glue than in other areas which have a greater quantity, said areas which have a greater quantity of glue form said deposits. This non-uniform distribution of the hot melt glue is due to the small quantity of hot melt glue coated on the layer of cellulose fiber.

[0032] Therefore, the hot melt glue is difficult to spread which forms hot melt glue aggregates on the cellulose fiber layer.

[0033] Thus, such a layer of hot-melt glue makes it possible to achieve sufficient bonding for packaging, in particular of press copies. However, the non-uniform distribution of the hot-melt glue deposits does not make it possible to obtain a watertight bond and is therefore not very suitable for use in the food sector, for example.

[0034] In a preferred embodiment, the deposits of hot melt adhesive are distributed inhomogeneously over the layer of cellulose fibers.

[0035] The random distribution of the hot melt glue deposits is due to the particular spreading of the hot melt glue. Indeed, since said glue is spread over a large surface, the hot melt glue groups together in random areas on the layer of cellulose fibers.

[0036] More particularly, the surface tension of the glue does not allow the formation of a uniform layer of glue and creates a non-uniform coating which forms a network of random bundles of glue.

[0037] In a particular embodiment, the layer of cellulose fibers comprises a mixture of long and short cellulose fibers.

[0038] In a particular embodiment, the proportion of long cellulose fibers being greater than the proportion of short cellulose fibers

[0039] In one embodiment, the layer of cellulose fibers comprises a thickness of between 20 and 50 micrometers.

[0040] The invention also relates to a method for manufacturing a heat-sealing paper according to the invention and comprises at least the steps of continuously supplying paper comprising at least one layer of cellulose fibers, continuously hot-coating the hot-melt glue on at least one face of the layer of cellulose fibers, cooling the hot-melt glue on the layer of cellulose fibers and continuously winding the heat-sealing paper.

[0041] In fact, the hot melt glue is hot coated over the entire length and width of the layer of cellulose fibers, which allows for a simple and effective coating step.

[0042] The step of coating the hot-melt glue is carried out continuously and in a single pass of the paper, that is to say that the face of the paper capable of being glued receives all of the hot-melt glue in a single coating.

[0043] In a particular embodiment, the coating step is carried out by a lip nozzle.

[0044] Preferably, the step of coating the hot melt adhesive layers an amount of hot melt adhesive so as to form discontinuous deposits of said hot melt adhesive on the layer of cellulose fibers.

[0045] The coating step is such as to form inhomogeneous deposits of said hot melt adhesive on the layer of cellulose fibers.

[0046] In a preferred embodiment, the hot melt adhesive coating step is carried out so as to coat between 1 and 8 grams of hot melt adhesive on the surface of the cellulose fiber layer per square meter.

[0047] Thus, a low grammage of glue per square meter of layer of cellulose fibers makes it possible to obtain a saving in raw materials, but also to carry out the coating step in a single pass, consequently reducing the production time and therefore increasing productivity, all while having sufficient gluing for packaging, in particular that of press copies.

[0048] In addition, the fact that the hot coating step is carried out on the entire face of the paper allows a great adaptability of the process according to the packaging machines and consequently a significant saving due to the absence of modification of the packaging machines, in particular of press copies. Indeed, usually the paper packaging films are glued and welded on precise points. However, these precise points change according to the dimensions of the objects to be packaged, such as press copies, making the processes specific to each packaging machine.

[0049] Preferably, the coating of the hot melt adhesive on at least one side of the cellulose layer is carried out in a single pass.

[0050] Thus, the process for manufacturing heat-sealing paper is accelerated because it no longer requires the successive application of several layers of glue, each separated by a drying step in order to reduce the proportion of water in the glue so as not to weigh down the layer of cellulose fibers, which can cause said cellulose fibers to break.

[0051] The invention also relates to a device for implementing the method for manufacturing heat-sealing paper according to the invention, said production device comprises at least one system for continuously supplying paper, at least one system for continuously coating the hot-melt glue on at least one side of the paper and at least one system for continuously winding the heat-sealing paper pre- clearly obtained.

[0052] In a particular embodiment, the continuous coating system for the hot melt glue comprises a lip nozzle in order to coat 1 to 8 grams of hot melt glue on one square meter of one face of the layer of cellulose fibers.

[0053] Thus, the face of the heat-sealing paper is licked by the lip nozzles depositing a small but sufficient quantity of hot-melt glue in order to be able to close the packaging envelope on itself, during the reactivation of the glue by a step of hot-sealing the heat-sealing paper on itself, during a packaging process using the heat-sealing paper according to the invention.

[0054] In another embodiment, the method comprises steps of packaging a product, in particular a press copy comprising steps of folding the heat-sealing paper onto itself, so as to package a product and a step of hot-cutting the previously folded heat-sealing paper.

[0055] Thus, the hot pressing of the heat-sealing paper reactivates the hot-melt glue layer of the heat-sealing paper, which allows the layers of cellulose fibers folded back on themselves to create bonds between the two layers of cellulose fibers via the hot-melt glue in order to package a product with the heat-sealing paper. Brief description of the figures

[0056] Other advantages and characteristics of the present invention are now described with the aid of examples which are purely illustrative and in no way limitative of the scope of the invention, and from the appended drawings, drawings in which the various figures represent:

[0057] [Fig-1] is a schematic side view of the heat-sealing paper, according to the invention.

[0058] [Fig.2] is a schematic perspective representation of the heat-sealing paper.

[0059] [Fig.3] is a schematic representation of the thermal paper manufacturing process moscellant, according to the invention.

[0060] In the following description, elements that are identical, by structure or by function, appearing in different figures retain, unless otherwise specified, the same references. Description of the embodiments

[0061] With reference to [Fig.l] to [Fig.3], the present invention relates to a heat-sealing paper 1 for packaging a product, in particular press copies.

[0062] The heat-sealing paper 1 comprises a layer of cellulose fibers 2 and a layer of hot-melt glue 3, said layer of hot-melt glue 3 is in contact of the cellulose fiber layer 2, so that when the paper 1 is exposed to a temperature of 180°C, the hot melt glue layer 3 melts and forms a bond with the cellulose fibers 2.

[0063] The layer of hot-melt glue 3 is deposited on the layer of cellulose fibers 2 discontinuously over the entire length and width of the layer of cellulose fibers 2, the layer of hot-melt glue having a melting point above a temperature of 100°C.

[0064] The heat-sealing paper 1 comprises a layer of hot-melt glue 3 deposited on the layer of cellulose fibers 2 with a density of three g / m2.

[0065] Thus, three grams of hot melt glue 3 are obtained on a surface area of ​​one square meter of the layer of cellulose fibers 2.

[0066] In this way, the heat-sealing paper 1 has non-uniform hot-melt glue dots 3, forming a random network of hot-melt glue dots 3.

[0067] The layer of cellulose fibers 2 and the layer of hot-melt glue 3 are arranged so that the deposition of the layer of hot-melt glue 3 on the layer of cellulose fibers 2 forms several deposits of said hot-melt glue 3 on the layer of cellulose fibers 2, said deposits being separated from each other on the layer of cellulose fibers 2.

[0068] The surface tension of the hot melt adhesive 3 forms several deposits of the hot melt adhesive 3 on the layer of cellulose fibers 2, said deposits being separated from each other on the layer of cellulose fibers 2. The deposits of the hot melt adhesive 3 are distributed inhomogeneously on the layer of cellulose fibers 2.

[0069] The heat-sealing paper 1 comprises a mixture of long and short cellulose fibers 2, more particularly the proportion of long cellulose fibers 2 represents 75% of the total cellulose fibers 2.

[0070] The layer of cellulose fibers 2 has a thickness of 37 micrometers.

[0071] The method 10 for manufacturing the heat-sealing paper 1 implements in a manner successively a step of continuously supplying paper comprising a layer of cellulose fibers 2, continuously hot-coating the hot-melt glue 3 on one side of the layer of cellulose fibers 2, cooling the hot-melt glue 3 on the layer of cellulose fibers 2 and continuously winding the heat-sealing paper 1.

[0072] The packaging method, in particular of press copies, comprises steps of welding and cutting the heat-sealing paper 1 by a welding system comprising a blade and at least one device for hot-pressing the heat-sealing paper 1. Thus, the cooled hot-melt glue 3 is reactivated, which makes it possible to properly bond two parts of the heat-sealing film together, in order to obtain satisfactory packaging for a press copy.

[0073] Indeed, in order to cut and weld the heat-sealing paper 1, the heat-sealing paper 1 is hot-pressed on either side of a blade in order to stretch the heat-sealing paper 1 at a precise point intended to be cut. The hot pressure reactivates the hot-melt glue and makes it possible to weld two parts of the heat-sealing paper together.

[0074] The coating step is carried out by a lip nozzle in a single pass of the layer of cellulose fibers 2 over the lip nozzle.

[0075] The method 10 layers between three grams of hot melt glue 3 per square meter on one side of the layer of cellulose fibers 2, over the entire width and length of the layer of cellulose fibers 2.

[0076] The coating step and the surface tension of the hot melt adhesive 3 form discontinuous deposits of said hot melt adhesive 3 on the layer of cellulose fibers 2.

[0077] The coating step is such as to form random deposits of said hot melt adhesive 3 on the layer of cellulose fibers 2.

[0078] The invention also relates to a device for implementing the method 10 for manufacturing heat-sealing paper 1 according to the invention.

[0079] The production device comprises a system 11 for continuously supplying paper, a system 12 for continuously coating the hot-melt glue 3 on one side of the paper and a system 13 for continuously winding the previously obtained heat-sealing paper 1.

[0080] The gluing system comprises a lip nozzle for applying three grams of hot melt glue 3 to one side of the layer of cellulose fibers 2.

[0081] The preceding description clearly explains how the invention makes it possible to achieve the objectives it has set itself, namely the reduction of the production cost of a press copy packaging, while being ecological and allowing great adaptability of the process to the different press copy packaging devices.

[0082] In any event, the invention cannot be limited to the embodiments specifically described in this document, and extends in particular to all equivalent means and to any technically effective combination of these means.

Claims

Claims

1. Heat-sealing paper (1) for packaging a non-food solid product comprising: - At least one layer of cellulose fibers (2); and - At least one layer of hot-melt glue (3), characterized in that the at least one layer of hot-melt glue (3) is deposited on the layer of cellulose fibers (2) discontinuously over the entire length and width of the layer of cellulose fibers, the layer of hot-melt glue having a melting point at a temperature above 80°C.

2. Paper (1) according to claim 1, characterized in that the layer of hot melt glue (3) is deposited on the layer of cellulose fibers (2) with a density of 1 to 8 g / m2.

3. Paper (1) according to claim 2, characterized in that the layer of cellulose fibers (2) and the layer of hot melt glue (3) are arranged so that the deposition of the layer of hot melt glue (3) on the layer of cellulose fibers (2) forms several deposits of said hot melt glue (3) on the layer of cellulose fibers (2), said deposits being interconnected with each other on the layer of cellulose fibers (2).

4. Paper (1) according to claim 3, characterized in that the deposits of the hot-melt glue (3) are distributed inhomogeneously on the layer of cellulose fibers (2).

5. Paper (1) according to one of the preceding claims, characterized in that the layer of cellulose fibers (2) comprises a mixture of long and short cellulose fibers (2).

6. Method (10) for manufacturing a heat-sealing paper (1) according to one of claims 1 to 5, characterized in that it comprises at least the steps of: - Continuously supplying a paper comprising at least one layer of cellulose fibers (2); - Continuously hot-coating a hot-melt adhesive (3) on at least one face of the layer of cellulose fibers (2); - Cooling the hot-melt adhesive (3) on the layer of cellulose fibers (2); and - Continuous winding of heat-sealing paper (1).

7. Method (10) according to claim 6, characterized in that the step of coating the hot melt glue (3) layers a quantity of hot melt glue (3) so as to form discontinuous deposits of said hot melt glue (3) on the layer of cellulose fibers (2).

8. Method (10) according to one of claims 6 or 7, characterized in that the step of coating the hot melt glue (3) is carried out so as to coat between 1 to 8 grams of hot melt glue (3) on the surface of the layer of cellulose fibers (2) per square meter.

9. Method (10) according to claim 8, characterized in that the coating of the hot-melt glue (3) on at least one face of the layer of cellulose fibers (2) is carried out in a single pass.

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