Heat-sealing paper for the filtration and packaging of a solid product

Abstract

The invention relates to heat-sealing paper (1) for packaging a solid product, comprising at least one layer of cellulose fibres (2), and at least one layer of hot-melt adhesive (3). According to the invention, the at least one hot-melt adhesive layer (3) is deposited on the cellulose fibre layer (2) in a discontinuous manner over the entire length and width of the cellulose fibre layer, the hot-melt adhesive layer having a melting point at a temperature above 80°C

Description

Description Title of the invention: HEAT-SEALING PAPER FOR FILTERING AND PACKAGING A SOLID PRODUCT technical field

[0001] The invention relates to the technical field of heat-sealing papers suitable for use for filtration, more particularly filtration in order for example to allow flavors to pass through while retaining impurities such as for example as tea or coffee bag paper or as paper to allow liquids or vapors to pass through.

[0002] The invention also relates to a method for manufacturing heat-sealing paper for use in particular as filter paper. State of the art

[0003] Depending on the application, packaging that allows fluids to pass through is sometimes necessary. For example, some applications require that flavors be allowed to pass through while preventing impurities from escaping, such as tea bags or coffee filters. Other applications, like packaging clothes after dry cleaning, require that the packaging be permeable to allow water to evaporate; otherwise, the garment cannot dry effectively. Generally, this garment packaging consists of a film made primarily of plastic.

[0004] However, in recent years, legislation in many countries has been reducing the use of plastic in all types of industries. Therefore, manufacturers of plastic films for product packaging, particularly clothing, must find alternative packaging materials to maintain their properties, such as low cost, good protection, and good ventilation.

[0005] For this purpose, manufacturers of product packaging films have replaced plastic with paper fiber packaging materials, where the fibers are glued to a specific location, on which the weld for closing the packaging is made.

[0006] However, this method requires highly adaptable machines to accommodate the varying dimensions of the solid products being packaged, such as clothing, but also tea bags. Indeed, the adhesive sealing of the packaging necessitates modifying the packaging devices to suit the different dimensions of the solid products.

[0007] Thus, in order to adapt to different dimensions, these devices must undergo heavy modifications resulting in a heavy and costly packaging process.

[0008] Alternatively, manufacturers have developed a heat-sealable paper packaging containing a layer of plastic, usually polyethylene terephthalate known as PET, which allows the plastic to be sealed. This eliminates the problem of machine compatibility, thus reducing the cost of the process. However, the use of plastic, even in small quantities, raises some issues. ecological.

[0009] Another method involves a water-based heat-sealing paper made by coating the paper with a cold, water-based adhesive.

[0010] This method requires applying a layer of aqueous-phase glue and then removing all the water present in the aqueous-phase glue, which is composed of approximately 60% water, in order to leave only pure glue or glue extract.

[0011] Thus, in order 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 great and would have the effect of damaging, or even breaking, the paper strip.

[0012] Therefore, manufacturers apply several successive layers of water-based glue, each layer being smaller. Each glue-coating step is followed by a hot-drying step to reduce the water content of the glue during the coating process. Consequently, this process is energy-intensive and expensive, making paper use very costly and thus limiting its use.

[0013] Furthermore, the nature of the cellulose fibers present in paper for these uses makes coating almost impossible. Indeed, because the cellulose fiber layer is open, meaning it has numerous pores, the aqueous adhesive passes through and / or is absorbed by the cellulose fiber layer, rendering the bond ineffective.

[0014] The invention therefore falls within this context and seeks to resolve all of the aforementioned drawbacks.

[0015] Thus, the invention seeks to produce a heat-sealing paper that is less expensive, ecological and adaptable to different garment packaging devices, while allowing for efficient filtration and ventilation. Presentation of the invention

[0016] The invention relates to a heat-sealing paper that is less expensive, environmentally friendly and adaptable to different garment packaging machines, while allowing efficient filtration and aeration.

[0017] An additional object of the invention relates to a method for manufacturing a fast and less expensive heat-sealing paper according to the invention, said paper being suitable for packaging, in particular clothing, but also suitable for filtration.

[0018] For this purpose, a heat-sealing paper has been developed for filtering and packaging a solid product comprising at least one layer of cellulose fibers, said cellulose fibers having a density between 0.9 and 1.6 g / cm³. 3 , a porosity between 50% and 90%, a surface treatment with hydrophobic or hydrophilic agents and at least one layer of hot melt adhesive.

[0019] According to the invention, at least one layer of hot-melt adhesive is deposited on the cellulose fiber layer, discontinuously over the entire length and width of the cellulose fiber layer, the hot-melt adhesive layer having a melting point at a temperature above 80°C.

[0020] It is therefore understood that the layer of hot melt adhesive does not contain water and is deposited hot, avoiding the long and costly process of cold application of the adhesive.

[0021] Thus, a heat-sealable paper without a layer of plastic material is obtained, allowing it to be produced in an environmentally friendly and less expensive way, 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.

[0022] Furthermore, the presence of a hot-melt adhesive layer eliminates the successive coating and drying steps required when using a cold, water-based adhesive, a process that is both cumbersome and expensive. Indeed, using a waterless adhesive applied with heat avoids the need for multiple layers of water-based glue.

[0023] Furthermore, the presence of a heat-activated hot-melt adhesive layer makes the heat-sealable paper suitable for any packaging device for solid products, including newspaper copies. Indeed, to seal the heat-sealable paper to itself for packaging, it is simply necessary to heat the heat-sealable paper sufficiently to reactivate the hot-melt adhesive.

[0024] Depositing the hot melt adhesive layer onto the cellulose fiber layer in a discontinuous manner creates a heat-sealing paper with a hot melt adhesive layer that is not evenly distributed over the cellulose fiber layer.

[0025] The paper can have a density of between 20 g / m 2 and 40 g / m 2 The paper can have a porosity ranging from 2800 cm³ (min-l-cm²) to 6200 cm³ (min-l-cm²). The application of a layer of hot, water-free glue in a paste-like consistency on the surface prevents the substance from penetrating the paper's porosity.

[0026] The term "discontinuous" refers to the fact that the hot melt adhesive layer is distributed unevenly across the entire width and length of the cellulose fiber layer.

[0027] Indeed, following the deposition of the hot melt adhesive layer on the cellulose fiber layer, said hot melt adhesive layer groups together into small aggregates arranged in an uncontrolled manner over the entire length and width of the cellulose fiber layer.

[0028] It is therefore understood that the term discontinuous relates to the random way in which the small aggregates of glue will be distributed on the layer of cellulose fibers and not to a discontinuous distribution because it is not continuous.

[0029] Similarly, we understand that the layer of cellulose fibers, by the density and porosity of its fibers, as well as by the treatments it undergoes depending on its use, makes it possible to produce a filtering or aerating packaging paper when used, particularly when used, for example, as a tea bag or as packaging paper for clothes coming out of the dry cleaners.

[0030] This type of paper can be used in dry cleaners and laundries so that water vapor is not retained inside the package after the bag is sealed.

[0031] This type of paper can be used as packaging for clothing sold online because it allows the paper to breathe, enabling moisture to evaporate and air to escape after sealing. This breathability helps prevent air pockets from forming and the packaging from becoming compressed in shipping containers.

[0032] The term "porosity between 50% and 90%" refers to the fact that the porosity of cellulose fibers can be measured in terms of the volume of the pores relative to the total volume of the cellulose fiber.

[0033] The treatment with hydrophobic or hydrophilic agents on the cellulose fiber layer can be total or partial depending on the use of the heat-sealing paper.

[0034] In a particular embodiment, the hot melt adhesive layer comprises a hot melt resin mixture in contact with the cellulose fiber layer, 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 thermoplastic polymer layer.

[0035] Preferably, the hot melt adhesive layer is deposited on the cellulose fiber layer with a density of 1 to 8 g / m². 2 .

[0036] In a more preferred embodiment, the hot melt adhesive layer is deposited on the cellulose fiber layer with a density of 2 to 5 g / m². 2

[0037] Preferably, the hot melt adhesive layer is deposited on the cellulose fiber layer in a single pass.

[0038] The term "density" refers to the fact that on a surface of one square meter of cellulose fiber, there are between 1 and 8 grams of hot melt glue.

[0039] Thus, using a small amount of hot melt glue reduces the manufacturing cost of such paper, while producing a heat-sealable paper with sufficient bonding for packaging solid products, including clothing, or even as tea bags.

[0040] In a particular embodiment, the cellulose fiber layer and the hot melt adhesive layer are arranged so that the deposition of the hot melt adhesive layer on the cellulose fiber layer forms several deposits of said hot melt adhesive on the cellulose fiber layer, said deposits being interconnected with each other on the cellulose fiber layer.

[0041] Thus, the surface tension of the hot melt glue and that of the cellulose fiber layer form several deposits of said hot melt glue on the cellulose fiber layer, said deposits remaining connected to each other on the cellulose fiber layer.

[0042] Thus, the layer of hot melt glue, through its surface tension, groups together into points of aggregates linked to the cellulose fibers.

[0043] Indeed, the amount of hot melt adhesive is such that its surface tension creates an unevenly deposited layer, forming areas with less adhesive than areas with more. These areas with more adhesive form the deposits. This uneven distribution of the hot melt adhesive is due to the small amount of adhesive applied to the cellulose fiber layer.

[0044] Consequently, the hot melt glue is difficult to spread, which forms aggregates of hot melt glue on the cellulose fiber layer.

[0045] Thus, such a layer of hot melt adhesive provides sufficient bonding for packaging solid products, particularly clothing. However, the uneven distribution of the hot melt adhesive deposits prevents a watertight seal and is therefore unsuitable for use with liquid products, for example.

[0046] In a preferred embodiment, the hot melt adhesive deposits are distributed inhomogeneously over the cellulose fiber layer.

[0047] The random distribution of hot melt adhesive deposits is due to the specific way the hot melt adhesive is spread. Because the adhesive is spread over a large area, it clumps together in small aggregates in random areas on the cellulose fiber layer.

[0048] More specifically, the surface tension of the glue does not allow the formation of a uniform glue layer and creates a non-uniform coating which forms a network of random glue beams.

[0049] In one particular embodiment, the cellulose fiber layer comprises a mixture of long and short cellulose fibers.

[0050] In a particular embodiment, the proportion of long cellulose fibers is greater than the proportion of short cellulose fibers.

[0051] In one embodiment, the cellulose fiber layer comprises a thickness of between 20 and 50 micrometers.

[0052] Preferably, the heat-sealing paper has a thickness between 0.1 and 0.4 millimeters.

[0053] Preferably, the cellulose fiber layer comprises between 20% and 80% long fibers and between 20% and 80% short fibers.

[0054] The term "long fibers" refers to cellulose fibers measuring over 2 millimeters, preferably between 2 and 3 millimeters.

[0055] As for "short fibers", this refers to cellulose fibers measuring less than 2 millimeters, preferably between 1 and 2 millimeters.

[0056] In one particular embodiment, the cellulose fiber layer comprises between 40% and 60% long fibers and between 40% and 60% short fibers.

[0057] In a preferred embodiment, the cellulose fiber layer comprises 45% long fibers and 55% short fibers.

[0058] In a particular embodiment, the cellulose fiber layer comprises cellulose fibers having a diameter between 10 and 30 micrometers.

[0059] Such dimensions of cellulose fibers make it possible to obtain fine cellulose fibers that can be organized in a three-dimensional way in order to create so-called "open" papers, that is to say, having enough space between the fibers in order to have such porosity, but also in such a way as to create a paper that can filter effectively or that can condition an object while allowing the latter to be aerated.

[0060] In a preferred embodiment, the cellulose fiber layer comprises between 50% and 80% microscopic pores ranging from 0.5 to 2 micrometers and between 20% and 50% macroscopic pores ranging from 5 to 50 micrometers.

[0061] With the aim of forming a filtering and aerating layer of cellulose fibers, the cellulose fiber layer comprises a composition with numerous microscopic and macroscopic pores.

[0062] The composition of cellulose fiber, particularly in terms of the distribution of microscopic and macroscopic pores, varies depending on its use.

[0063] Preferably, microscopic and macroscopic pores are uniformly distributed in the cellulose fiber layer.

[0064] The invention also relates to a method for manufacturing a heat-sealing paper according to the invention and includes at least the steps of continuously supplying paper comprising at least one layer of cellulose fibers, treating the cellulose fiber layer with hydrophobic or hydrophilic agents, continuously hot-coating the hot-melt adhesive on at least one face of the cellulose fiber layer, said hot-melt adhesive coating being carried out so as to deposit between 1 and 8 grams of hot-melt adhesive on the surface of the cellulose fiber layer per square meter, so as to form discontinuous deposits of said hot-melt adhesive on the cellulose fiber layer, cooling the hot-melt adhesive on the cellulose fiber layer and continuously winding the heat-sealing paper.

[0065] Indeed, the hot melt adhesive is hot-coated over the entire length and width of the cellulose fiber layer, resulting in a simple and efficient coating step.

[0066] The hot melt glue coating step is carried out continuously and in a single pass of the paper, that is to say that the side of the paper suitable for gluing receives the entire hot melt glue in a single coating.

[0067] In one particular embodiment, the coating step is carried out by a lip nozzle.

[0068] Preferably, the hot melt adhesive coating step coats a quantity of hot melt adhesive so as to form discontinuous deposits of said hot melt adhesive. on the cellulose fiber layer

[0069] The coating stage is such as to form inhomogeneous deposits of said hot melt glue on the cellulose fiber layer.

[0070] Thus, a low grammage of glue per square meter of cellulose fiber layer allows for a saving of raw materials, but also the completion of the coating step in a single pass, consequently reducing production time and therefore increasing productivity, all while having sufficient bonding for the packaging of solid products, including clothing, tea or coffee.

[0071] Furthermore, the fact that the hot coating step is applied to the entire surface of the paper allows for a high degree of process adaptability to different packaging machines, resulting in significant cost savings due to the absence of modifications to packaging machines for solid products, particularly press copies. Indeed, paper packaging films are typically glued and sealed at specific points. However, these points vary depending on the dimensions of the solid objects being packaged, such as press copies, making the processes specific to each packaging machine.

[0072] Preferably, the hot melt adhesive is applied to at least one side of the cellulose layer in a single pass.

[0073] Thus, the manufacturing process of heat-sealable paper is accelerated because it no longer requires the successive application of several layers of glue, each separated by a drying step to reduce the glue's water content and prevent it from weighing down the cellulose fiber layer, which can lead to breakage of the cellulose fibers. Brief description of the figures

[0074] Other advantages and features of the present invention are now described by means of purely illustrative and in no way limiting examples of the scope of the invention, and from the accompanying drawings, in which the various figures represent:

[0075] [Fig. 1] is a schematic side view representation of the heat-sealing paper, according to the invention.

[0076] [Fig. 2] is a schematic perspective representation of the heat-sealing paper.

[0077] [Fig. 3] is a schematic representation of the process for manufacturing heat-sealing paper, according to the invention.

[0078] In the description that follows, identical elements, by structure or by function, appearing on different figures retain, unless otherwise specified, the same references. Description of the implementation methods

[0079] With reference to [Fig. 1] to [Fig. 2], the present invention relates to a heat-sealing paper 1 for the packaging of a solid product, in particular clothing or tea or coffee.

[0080] 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 with the layer of cellulose fibers 2, so that when the paper 1 is exposed to a temperature of 180°C, the layer of hot melt glue 3 melts and forms a bond with the cellulose fibers 2.

[0081] More specifically, and in order to obtain a heat-sealable paper 1 that can effectively filter tea as packaging paper, the cellulose fiber layer 2 has a density of 1 g / cm³ 3 , as well as a porosity of 80%.

[0082] Similarly, to effectively filter the tea, specifically to allow the flavors to infuse into the water without any solid particles remaining, the cellulose fibers undergo treatment with hydrophobic agents. This treatment, while not departing from the scope of the invention, may be partial or complete.

[0083] The hot melt adhesive layer 3 is deposited on the cellulose fiber layer 2 discontinuously over the entire length and width of the cellulose fiber layer 2, the hot melt adhesive layer having a melting point above a temperature of 100°C.

[0084] The heat-sealable paper 1 comprises a layer of hot-melt adhesive 3 deposited on the layer of cellulose fibres 2 with a density of three g / m 2 .

[0085] Thus, three grams of hot melt glue 3 are obtained on a surface of one square meter of the cellulose fiber layer 2.

[0086] In this way, the heat-sealable paper 1 has non-uniform hot melt glue dots 3, forming a random network of hot melt glue dots 3.

[0087] The cellulose fiber layer 2 and the hot melt adhesive layer 3 are arranged so that the deposition of the hot melt adhesive layer 3 on the cellulose fiber layer 2 forms several deposits of said hot melt adhesive 3 on the cellulose fiber layer 2, said deposits being separated from each other on the cellulose fiber layer 2.

[0088] The surface tension of the hot melt adhesive 3 forms several deposits of the hot melt adhesive 3 on the cellulose fiber layer 2, said deposits being separated from each other on the cellulose fiber layer 2. The deposits of the hot melt adhesive 3 are distributed inhomogeneously on the cellulose fiber layer 2.

[0089] Heat-sealing paper 1 comprises a mixture of long and short cellulose fibers 2, more specifically the proportion of long cellulose fibers 2 represents 80% of the total cellulose fibers 2, i.e. 20% of short cellulose fibers.

[0090] The cellulose fiber layer 2 is 50 micrometers thick, for a heat-sealing paper thickness of 0.1 of 0.5 millimeters.

[0091] Still with the aim of obtaining a heat-sealing filter paper 1, the cellulose fiber layer 2 comprises 80% microscopic pores with an average of 0.8 micrometers and 20% macroscopic pores with an average of 23 micrometers.

[0092] As illustrated in [Fig. 3], process 10 for manufacturing heat-sealable paper 1 puts in works successively a step of continuous supply of paper comprising a layer of cellulose fibers 2, of treatment of the layer of cellulose fibers 2 with hydrophobic agents, of continuous hot coating of the hot melt adhesive 3 on one face of the layer of cellulose fibers 2, said coating of the hot melt adhesive 3 is carried out so as to coat between 1 and 8 grams of hot melt adhesive 3 on the surface of the layer of cellulose fibers 2 per square meter, so as to form discontinuous deposits of said hot melt adhesive on the layer of cellulose fibers, of cooling of the hot melt adhesive 3 on the layer of cellulose fibers 2 and of continuous winding of the heat-sealing paper 1.

[0093] The process for packaging solid products, particularly tea, includes welding and cutting steps of the heat-sealable paper 1 by a welding system comprising a blade and at least one hot press device for the heat-sealable paper 1. Thus, the cooled hot melt adhesive 3 is reactivated, which allows two parts of the heat-sealable film to be properly glued together, in order to obtain packaging for solid products, satisfactory in particular for tea.

[0094] Indeed, in order to cut and seal the heat-sealable paper 1, the heat-sealable paper 1 is hot-pressed on either side of a blade to stretch it at a precise point intended for cutting. The hot pressure reactivates the hot-melt adhesive and allows the two parts of the heat-sealable paper to be sealed together.

[0095] The coating step is carried out by a lip nozzle in a single pass of the cellulose fiber layer 2 over the lip nozzle.

[0096] The process 10 applies three grams of hot melt adhesive 3 per square meter to one face of the cellulose fiber layer 2, over the entire width and length of the cellulose fiber layer 2.

[0097] The coating stage and the surface tension of the hot melt adhesive 3 form discontinuous deposits of said hot melt adhesive 3 on the cellulose fiber layer 2.

[0098] The coating step is such as to form random deposits of said hot melt glue 3 on the cellulose fiber layer 2.

[0099] The preceding description clearly explains how the invention achieves its objectives, namely reducing the production cost of packaging for solid products, while being environmentally friendly and allowing great adaptability of the process to different packaging devices for solid products, all while providing a filtering and aerating paper.

[0100] 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 operative combination of these means.

Claims

Demands

1. Heat-sealable paper (1) for filtering and packaging a solid product comprising: At least one layer of cellulose fibres (2), said cellulose fibres comprising a density between 0.9 and 1.6 g / cm² 3 , a porosity between 50% and 90%, a surface treatment with hydrophobic or hydrophilic agents; and At least one layer of hot melt adhesive (3), Characterized in that at least one layer of hot melt adhesive (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 adhesive having a melting point at a temperature above 80°C.

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

3. Paper (1) according to claim 2, characterized in that the cellulose fiber layer (2) and the hot melt adhesive layer (3) are arranged so that the deposition of the hot melt adhesive layer (3) on the cellulose fiber layer (2) forms several deposits of said hot melt adhesive (3) on the cellulose fiber layer (2), said deposits being interconnected with each other on the cellulose fiber layer (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 any one of the preceding claims, characterized in that the cellulose fibre layer (2) comprises a mixture of long and short cellulose fibres (2).

6. Paper (1) according to the preceding claim, characterized in that the cellulose fibre layer (2) comprises between 20% and 80% long fibres and between 20% and 80% short fibres.

7. Paper (1) according to any one of the preceding claims, characterized in that the cellulose fibre layer (2) comprises cellulose fibres comprising a diameter between 10 and 30 micrometres.

8. Paper (1) according to any one of the preceding claims, characterized in that the cellulose fibre layer (2) comprises between 50% and 80% microscopic pores ranging from 0.5 to 2 micrometres and between 20% and 50% macroscopic pores ranging from 5 to 50 micrometres.

9. Paper (1) according to the preceding claim, characterized in that the microscopic and macroscopic pores are uniformly distributed in the cellulose fiber layer (2).

10. A method (10) for manufacturing a heat-sealable paper (1) according to any one of claims 1 to 5, characterized in that it comprises at least the steps of: Continuous supply of paper comprising at least one layer of cellulose fibres (2); Treatment of the cellulose fibre layer (2) with hydrophobic or hydrophilic agents; Continuous hot coating of a hot melt adhesive (3) on at least one face of the cellulose fiber layer (2), said coating of the hot melt adhesive (3) is carried out so as to coat between 1 and 8 grams of hot melt adhesive (3) on the surface of the cellulose fiber layer (2) per square meter, so as to form discontinuous deposits of said hot melt adhesive on the cellulose fiber layer; Cooling of the hot melt adhesive (3) on the cellulose fiber layer (2); and Continuous winding of heat-sealing paper (1).

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