TW201609398A - Heat-sealing barrier paper - Google Patents

Abstract

The present invention relates to a paper comprising: - a fibrous substrate, - a precoat layer comprising a binder and a mixture of platy filler(s) having a shape factor of at least 15 and of finer filler(s), the size of the particles of which is, for 80% by weight, less than 2 [mu]m (measured according to the ISO 13317-3 SediGraph method), - at least one covering layer applied to the precoat layer, the paper having a water vapour permeability of at most 150 g/m2/24 h and preferably of less than 100 g/m2/24 h, measured according to the ASTM F1249 standard under so-called tropical conditions of 38 DEG C and 90% relative humidity.

Description

Heat seal barrier paper

The present invention relates to the field of wrapping paper.

Plastic films are widely used in flexible packaging because they have the water vapor barrier properties necessary to preserve perishable products or products with limited shelf life.

Paper is a material made from fibers, usually cellulosic fibers, and is therefore of plant origin. It is naturally porous and permeable to gases and is not itself useful for this application.

However, it is known to combine paper with other materials (plastic, aluminum, etc.) in order to obtain the barrier necessary to package various products and especially perishable foods. In this case, the paper substrate is subjected to a conversion operation including, for example, coating a cover layer made of a polymer dispersion, extrusion coating a molten polymer or laminating with a plastic or aluminum film. The cost of this paper-based composite with barrier properties becomes expensive.

Document US 2 653 870 A describes a method for producing packaging paper.

A package made of barrier paper made in-line is described in application WO 2011/056130. Online manufacturing is understood to mean manufacturing on a single production tool that contains all the components needed to produce paper.

However, the proposed barrier level is limited to measurement conditions that are not very restrictive (temperate, ie, 25 ° C, 75% relative humidity). The barrier level is measured by water vapor permeability, and the weak barrier indicates high water vapor permeability. It is known that the "tropical" conditions (i.e., 38 ° C, 90% relative humidity) are more severe than the temperate conditions in the literature, and therefore the barriers measured under temperate conditions are weak.

The expression "barrier paper" is understood to mean a non-porous paper comprising a fibrous substrate covered with one or more layers which is sufficiently dense to be vaporized to withstand adverse effects on the preservation or internal containment of the product. The amount of integrity of the product penetrates into the package.

In particular, but not exclusively, the present invention focuses on water vapor permeability measured under so-called tropical conditions of 38 ° C and 90% relative humidity according to ASTM F1249 standard of at most 150 g/m ² /24 h and preferably less than 100 g/m ² / 24h water vapor barrier paper.

The barrier paper is also preferably heat sealable to allow the package to be formed by sealing the paper to itself.

The manufacture of heat sealable paper involves, for example, laying a cover layer of a heat sealable polymer on a cellulosic substrate. The cover layer is very viscous when not dry and must be completely dry before the paper is wound on itself to avoid the individual turns of the reel sticking to each other.

The application of this cover layer is typically carried out off-line during one or more conversion steps, which makes it possible to have good coating quality, benefiting from the coating of the paper at ambient temperature so that the cover layer does not penetrate excessively into the fibrous support. The cloth is timed and the roll width can be adjusted in the oven to a speed of, for example, about 200 m/min, such that the time of exposure to the heating means is sufficient to completely dry the heat seal cover in depth.

Documents for offline processing are disclosed in the documents US 2004/121079 A1, WO 2010/052571 A2, US 2014/113080 A1 and WO 2009/112255 A1.

Papers that provide a barrier to water vapor and optionally heat seal are typically manufactured in the prior art during the conversion operation, and conventionally have a cover layer of 10 to 30 g/m ² when dried, using various coating means for the cover layers. (Air knife, reverse gravure, Meyer rod or Meyer rod or any other coating method) or deposited by applying a thick layer using curtain coating to one or more thicknesses.

In order to impart water vapor barrier and heat sealability characteristics to paper, off-line conversion of paper is therefore an additional step in the paper manufacturing process, which significantly increases its cost and limits the development of paper in flexible packaging that is biased toward plastic film packaging. Therefore, there is an economic need to improve the manufacture of water vapor resistance. The productivity of the heat-sealed paper is separated.

The present invention relates to the development of paper which is imparted with water vapor barrier and heat sealability during on-line manufacturing of paper. This barrier and heat seal paper can be used to make a package by sealing the paper to itself.

Regardless of the manner in which the heat seal layer is applied either online or offline, the problem is to promote deposition of the heat seal layer and, more generally, any heat seal or non-heat seal cover applied to the fiber matrix.

It is generally desirable that the cover layer not penetrate deeply into the fibrous matrix to reduce the amount applied to the paper when the layer is based on the polymer. In addition, less penetration of the cover layer makes it easier to form the barrier film.

The use of a Yankee cylinder is the first solution for reducing surface porosity.

The second option is to use a calender before any processing of the paper.

Another option is to provide the presence of a precoat to reduce the porosity of the paper.

Another option is to combine one or the other of the foregoing options.

Certain hydrophobic and highly film-forming latexes can be used in the formulation of the precoat.

However, when the cover layer contains water, the hydrophobicity of the precoat layer may subsequently cause problems with wettability during application of the cover layer, resulting in incomplete coverage of the precoated fiber matrix, particularly in the case of in-line methods using high speed sheets. . In addition, while adhering to the well-known wettability principle, the surface energy of the precoat layer must be sufficiently different from the surface energy of the cover layer in order to reduce the risk of wetting defects.

Therefore, there is still a need to respond satisfactorily to the issue of the applicability of the cover layer.

The present invention meets this need according to one aspect thereof, the paper comprising: a fibrous substrate, a precoat comprising a binder and a plate-shaped filler having a shape factor of at least 15 and a filler, especially a fine filler. a mixture of 80% by weight of the finer filler having a particle size of less than 2 μm (measured according to the ISO 13317-3 SediGraph method), at least one applied to the precoat layer, the paper being at 38 ° C according to ASTM F1249 The water vapor permeability measured under so-called tropical conditions of 90% relative humidity is at most 150 g/m ² /24 h and preferably less than 100 g/m ² /24 h.

In the precoat according to this aspect of the invention, there is a plate-like filler having a shape factor of at least 15 and a finer (especially non-plate-like) having an 80% by weight particle size of less than 2 μm as measured according to the ISO 13317-3 SediGraph method. The particulate filler allows a relatively high barrier level to be obtained regardless of the hydrophobic or non-hydrophobic nature of the binder.

It is known that platy fillers help to increase the barrier effect due to the degree of distortion provided by them, as taught , for example, by the literature Imerys Technical Guide, Pigments for Paper (May 2008) . According to this aspect of the invention, the presence of at least one finer (especially non-plate) particulate filler increases this effect. One experimental explanation for this is that the filler hinders the movement of water molecules by sliding between the plate-like particles, and even more particularly around the plate-like particles. Document WO 2009/117040 A1 discloses a platy filler for clay.

Due to the barrier effect associated with the particular choice of filler present in the precoat, there is a greater degree of freedom with regard to the nature of the binder used.

In particular, any papermaking adhesive without specific barrier properties can be used which provides the dual advantages of low water vapor permeability of the precoat and good wettability of the cover layer.

The invention makes it possible to have a reinforced barrier effect in the case of the use of a precoat, thereby allowing to reduce the amount of cover layer to be applied, or for an equal amount of cover layer, so that the barrier level of the paper can be further increased, thereby proving Suitable for paper that must not leak water vapor. Due to the greater barrier capability of the precoated paper, the reduction in the amount of cover layer required accelerates its drying and makes coating of this layer easier during on-line manufacturing of the paper.

The paper of the present invention is preferably composed of free cellulose fibers on a paper machine and is optionally combined Fibrous matrix fiber production.

Cellulose fibers are generally a mixture of short fibers and long fibers.

Additives such as sizing agents, wet strength agents, retention agents or antifoaming agents may be added.

The paper may also contain paper fillers such as, for example, titanium dioxide, kaolin, calcium carbonate and talc.

The paper is preferably a wrapper.

A further subject of the invention is a precoated paper suitable for the manufacture of a barrier paper according to the invention as defined above, which has a water vapor permeability of at most 150 g/m ² /24h and preferably less than 100 g/m according to the aforementioned criteria. ² / 24h. Pre-coated paper can be unglazed.

A further subject of the invention is a precoat composition for the manufacture of a paper according to the invention comprising a binder in the form of a latex and a dispersion of a mixture of a plate-like filler having a shape factor of at least 15 and a finer filler. The liquid, 80% by weight of the finer filler has a particle size of less than 2 μm.

A further subject of the invention is a package comprising paper according to the invention, in particular heat sealed to itself and containing, for example, a food product.

A further subject of the invention is a process for the manufacture of a paper according to the invention, wherein a precoat composition as defined above is applied to a fibrous substrate.

A further subject of the invention is a process for the manufacture of a barrier paper, in particular according to the invention, for water vapour, in particular under the so-called tropical conditions of 38 ° C and 90% relative humidity according to the ASTM F1249 standard. Permeability is at most 150 g/m ² /24 h and heat sealable, wherein at least one cover layer comprising at least one thermoplastic film-forming polymer is applied in-line to the paper machine and the fibrous substrate, and in particular after covering the in-line application of the pre-coating A layer is applied to the precoat layer.

The speed of paper production can be greater than or equal to 300 m/min, preferably greater than or equal to 400 m/min, and even more preferably greater than or equal to 500 m/min.

The hole filling composition can be applied to the fiber on-line prior to applying any layer or pre-coating on-line The matrix, the pore filling composition is preferably applied by a size press or a film press.

Another subject of the invention is an adjustment method in which 330 mm per bag is placed on a VFFS (vertical forming, filling and sealing) type of vertical packaging machine, especially at a manufacturing rate of 40 bags per minute or more. The longitudinally sealed line heat seals the object to be packaged by the paper obtained according to the manufacturing method of the present invention to itself.

Precoat

The precoat layer may be the same as the cover layer or a pigment layer as defined below.

The precoat layer preferably consists of a mixture of at least one latex and a filler sometimes also referred to as "pigment".

Document US 4 018 647 A describes an example of a latex.

The latex according to the present invention preferably has a _Tg (glass transition temperature) measured according to the ASTM E1356 standard of less than 25 ° C and more preferably less than 10 ° C. The latex may be selected from the following chemical emulsions: styrene-butadiene, styrene-acrylic acid, acrylic acid, butyl acrylate, butyl acrylate-styrene-acrylonitrile, and the like, and more specifically selected from styrene-butyl Diene emulsion.

The amount of the latex is preferably at least 15 dry parts relative to the filler (100 parts) at the time of drying, preferably at least or even more than 25 parts per hundred parts of the filler and more preferably 30 parts.

The filler is preferably composed of a mixture of a plate-like filler and a finer (especially non-plate-like) filler.

The platy filler is a particle in the form of a thin layer having a shape factor (ratio between the maximum length and the maximum thickness) of greater than or equal to 15, more preferably at least 40 and even more preferably at least 60.

The precoat layer comprises a binder and a mixture of a plate-shaped filler having a shape factor of at least 15 and a finer filler, especially a non-plate filler, the particle size of the finer filler 80% by weight being less than 2 μm (according to ISO 13317-3 SediGraph method measurement).

In order to have a mixture of a plate-like filler and a finer filler, the particle size of 80% by weight of the finer filler is less than 2 μm, and the particle size of 80% by weight of the plate-like filler may be, for example, greater than or equal to 2 μm. According to another example, less than 80% by weight of the plate-like particles may Less than 2 μm.

In other words, in order to have a filler finer than the plate-like filler, according to the first example, the particle size of the finer filler may be lower than the particle size of the plate-like filler at an equal weight distribution. According to a second example, for particles of the same size, the weight distribution may be greater than the weight distribution of the platy filler.

The finer fillers may be selected from all other pigments used in papermaking to meet the desired dimensional conditions.

The percentage of the plate-like filler relative to the total of the filler may range from 10% to 90%, preferably from 40% to 90% and still more preferably from 60% to 90%.

The platy filler may, for example, be selected from the group consisting of kaolin and talc, and mixtures thereof.

The size of the plate-like particles of 30% by weight to 80% by weight may be less than or equal to 2 μm (measured according to the ISO 13317-3 SediGraph method). The particles of the platy filler are oriented in particular substantially parallel to the surface of the substrate.

The particles of the finer filler may be selected from the group consisting of calcium carbonate, barium sulfate, cerium oxide, titanium dioxide, mixtures thereof and the like. It is characterized by measuring the particle size of 80% by weight less than 2 microns according to the ISO 13317-3 SediGraph method.

The finer fillers may also be selected from any other pigments, including kaolin, having a fineness, in particular 95% by weight, according to the ISO 13317-3 SediGraph method, having a particle size of less than 2 microns.

The binder is preferably selected from the foregoing latexes, but other binders such as PVOH, starch, CMC, or a secondary binder may be used. The binder may comprise a polymer that is not chemically present in the cover layer.

Cover layer

The polymer used to obtain vapor barrier and heat sealability is preferably selected from polymers or copolymers based on PVdC (polyvinylidene chloride) or acrylic acid.

These polymers are applied neat or in the form of a mixture with a filler. The term "pure" Solution means no particle filler. Other products may optionally be added to the dispersion of the polymer, such as a pH control agent, a rheological (e.g., tackifying) agent, an antifoaming agent, a wetting agent, and the like.

The use of fillers in the cover layer can especially help reduce the risk of the reels being stuck to each other.

Manufacturing

Preferably, the cover layer is applied in-line.

The present invention makes it possible to obtain a good water vapor barrier level in which the weight of the cover layer does not exceed 10 g/m ² when dried.

Although the speed of paper applied by an industrial paper machine is relatively high, for example about 400 m/min, it is possible to apply a composition that is intended to form a heat seal cover layer on-line, provided that sufficient drying ability is used to dry before the winding operation. This layer. In particular, a relatively low weight cover layer accelerates on-line drying while providing adequate barrier properties.

The online method makes it possible to increase productivity by removing processing operations associated with off-line processing.

After drying the fibrous substrate, the paper flakes can be transferred to a Yankee dryer to improve the surface finish of the flakes and thus improve the distribution of the first layer.

The sheet can then be processed in a size press or any other device of the same type. In order to avoid excessive penetration of the precoat into the fibrous support, the pigment composition may be used in advance for "hole filling".

The pore-filling composition may contain up to 20 dry parts of a binder such as, for example, styrene-butadiene chemistry, and a binder such as starch, relative to the dry pigment when dried. Adhesive.

Preferably, the composition contains a filler of generally less than 2 microns in size. These fillers may in particular be chosen from kaolin or calcium carbonate or mixtures thereof.

The precoat layer is applied to the support thus treated using any coating technique that can be performed on a papermaking machine. This can be in particular a knife coating, a rotary gravure coating, a reverse gravure coating or a Meyer bar coating. The precoat layer is deposited to a dry layer weight of preferably between 4 and 12 g/m ² .

The precoat layer is then dried without contact by one or more infrared ovens and/or one or more hot air ovens.

It is not necessary to have a very high level of smoothness before applying the cover layer. The Bekk level of 150 seconds is sufficient (measured according to the ISO 5627 standard).

The water vapor barrier and heat seal cover layer is applied by using any coating technique that can be performed on a papermaking machine. This can be, for example, knife coating, rotogravure coating, reverse gravure coating or Meyer bar coating. The precoat layer is deposited to a dry layer weight of preferably up to 10 g/m ² .

The cover layer is then sufficiently dried using one or more infrared ovens and/or one or more hot air ovens to prevent the backing from sticking to the winding drum.

Coating may be performed on the opposing surface to enhance the barrier and/or to provide other functionality such as printability, curl correction, and the like.

The paper thus produced can be calendered on-line as appropriate to reduce the surface roughness before winding.

The final basis weight of the paper can be between 45 and 200 g/m ² .

The barrier to water vapor measured at 38 ° C and 90% relative humidity according to ASTM F1249 is less than 150 g/m ² /24 h, and preferably less than 100 g/m ² /24 h.

Example 1:

A fiber support having a basis weight of 55 g/m ² was produced on a paper machine operating at 400 m/min. The paper machine is equipped with a Yankee dryer placed in front of the size press.

First glazing the fiber support, followed by in-line processing of the pigment composition on both sides with a pore-filling pigment composition comprising 100 dry portions of the Amazon Premium type of kadam, and in relation to A mixture of dried kaolin 20 dry portions in a ratio of Merifilm 104 starch (Tate & Lyle) and DL950 type latex (Dow). The applied treatment dried up to a total of 5 g/m ² .

It was then precoated with a mixture of a plate-like filler and a finer particle filler and a styrene-butadiene chemistry of _Tg = 7 °C (DL950 from Dow Chemical) using a Meyer bar coater. The formulation was coated and dried in an infrared oven followed by a hot air oven without contact. It is then wound onto a reel without any other treatment. The applied precoat had a dry weight of 7 g/m ² and its formulation is given in the table below:

The particle size of Amazon Premium 97% by weight was measured to be less than 2 microns according to the ISO 13317-3 SediGraph method.

The shape factor for Capim NP particles is 28.

The barrier to water vapor was measured by a Mocon Permatran 3/61 machine at 38 ° C and 90% relative humidity according to ASTM F1249 to determine the barrier contribution of this precoat. Measured at 334 ± 13 g / m ² / 24 h. After coating with the cover layer, a barrier of less than 150 g/m ² /24 h is obtained.

Example 2:

The fiber support is first glazed and then processed online by a size press with a hole-filled pigment composition on both sides thereof, the pigment composition containing 100 dry portions of Amazon Premium type kaolin, and in relation to A mixture of dried kaolin 20 dry portions in a ratio of Merifilm 104 starch (Tate & Lyle) and DL950 latex type (Dow). The applied treatment dried up to a total of 5 g/m ² .

It was then coated with a formulation containing a mixture of a plate-like filler and a finer particle filler and a styrene-butadiene chemistry of Tg = 7 ° C (DL950 from Dow Chemical) using a Meyer bar coater. The cloth was dried in an infrared oven followed by a hot air oven without contact. It is then wound onto a reel without any other treatment. The applied precoat had a dry weight of 7 g/m ² and its formulation is given in the table below:

The particle size of Hydrocarb 95 95% by weight was measured to be less than 2 microns according to the ISO 13317-3 SediGraph method.

The barrier to water vapor was measured by a Mocon Permatran 3/61 machine at 38 ° C and 90% relative humidity according to ASTM F1249 to determine the barrier contribution of this precoat. Measured at 315 ± 9 g / m ² / 24 h. After coating with the cover layer, a barrier of less than 150 g/m ² /24 h is obtained.

Example 3:

Paper was produced on-line under the same conditions as in Example 1. After deposition of the precoat, it was applied in-line with a cover layer consisting of a dispersion of PVdC copolymer (Diofan A297 from Solvay) and dried in an infrared oven followed by no contact in a hot air oven. It was then wound onto a reel without other treatment and no joint between the turns was observed. The dry weight of the cover layer was 6.5 g/m ² .

The barrier to water vapor was measured by a Mocon Permatran 3/61 machine at 38 ° C and 90% relative humidity according to ASTM F1249. It was measured at 21.0 ± 2.4 g/m ² /24 h.

The surface covered with the cover layer was then bonded to the surface by itself at 110 ° C at 3 bar for 0.5 seconds on the laboratory heat sealing machine. Next, then at a 90 degree angle The force required to separate the paper bonded to the sample having a width of 15 mm was measured at a speed of 100 mm/min according to the Tappi T540 standard.

A sealing force of 3.5 N/15 mm is obtained.

The invention is not limited to the examples described.

In summary, the present invention may have one or more of the following advantageous features: the weight of the cover layer is no more than 10 g/m ² when dry, in particular strictly less than 10 g/m ² , and the cover layer comprises a heat sealable polymer or The heat-sealable polymer is composed of a plate-like filler and a finer filler. The shape factor of the plate-like filler particles is at least 40, more preferably at least 60, and the finer filler is a non-plate-like filler, which is finer. The filler is a platy filler, and the finer filler is measured according to the ISO 13317-3 SediGraph method with a particle size of 95% by weight of less than 2 microns.

The plate-shaped filler is an inorganic filler, the finer filler is an inorganic filler, the plate-shaped filler is selected from the group consisting of kaolin and talc, and a mixture thereof, and the fine filler is selected from the group consisting of kaolin, calcium carbonate, barium sulfate, vermiculite, Titanium dioxide and mixtures thereof, the finer filler is selected from kaolin, the dry weight of the plate filler is between 3% and 58% of the total dry weight of the precoat, and the weight of the plate filler is preferably greater than the finer filling. The weight of the agent, the dry weight of the finer filler is between 3% and 58% of the total dry weight of the precoat, the percentage of the plate filler expressed by dry weight relative to the sum of the fillers expressed by dry weight is between 10% and 90%, and preferably 40% and still more preferably between 90% and between 60% and 90%, of the binder the glass transition temperature T _g of lower than 25 ℃ or equal to 25 deg.] C and More preferably less than 10 ° C, the binder is selected from the group consisting of styrene-butadiene, styrene-acrylic acid, acrylic acid, butyl acrylate, butyl acrylate-styrene-acrylonitrile chemistry latex, and mixtures thereof.

The binder is selected from the group consisting of styrene-butadiene chemistry latex, and the binder is introduced in the form of a latex. The precoat layer comprises at least 15 dry parts, preferably more than 25 parts by weight relative to the weight of the filler when dried (100 parts). a dry portion, preferably 30 dry parts of the binder, the binder comprises a chemically non-polymeric polymer present in the cover layer, the cover layer is substantially free of filler, and the cover layer is the only layer covering the precoat layer, covering The layer comprises one or more polymers selected from the group consisting of PVdC-based or copolymers based on styrene-acrylic acid and mixtures thereof, the amount of precoat layer being less than or equal to 12 g/m ² on a dry basis, and the paper being pre-coated with a matrix The coated surface of the coating and the cover layer comprises a printed layer on the opposite side of the substrate, the substrate having two identical precoats on its opposite side, the substrate having two different precoats on its opposite side Applying the pore filling composition to the substrate and applying the precoat layer to the pore filling composition, the pore filling composition is preferably applied by a size press or a film press having a basis weight of 25 and 180 g/m ² Between when it is sealed at 3 bar for 0.5 s by hot clip The paper is heat sealable, in particular starting at 90 ° C, the water vapor permeability of the barrier paper is less than 100 g / m ² / 24h.

30% by weight to 80% by weight of the plate-like particles having a size of less than or equal to 2 μm (measured according to the ISO 13317-3 SediGraph method), at a manufacturing rate of 40 bags or more per minute, at VFFS (vertical formation, filling and On a vertical packaging machine of the type of seal), along the longitudinal sealing line of 330 mm per bag, the paper can be heat-sealed, especially heat-sealable to itself, when sealed at 3 bar for 0.5 s by means of a hot clip, the paper is The sealing force of greater than or equal to 2N/15mm can be heat sealed to itself at a 90 degree angle according to the Tappi T540 standard at a speed of 100 mm/min. The temperature of the fibrous substrate is higher than or equal to 50 °C during the application of the precoat. The temperature of the fibrous substrate during application of the cover layer is greater than or equal to 70 ° C and the final basis weight of the paper is between 45 and 200 g/m ² .

The expression "includes one" should be understood as synonymous with "including at least one."

Claims (41)

A paper comprising: a fibrous substrate, a precoat comprising a binder and a mixture of a plate-shaped filler having a shape factor of at least 15 and a finer filler (especially a non-plate filler), the (etc.) being finer 80% by weight of the filler has a particle size of less than 2 μm (measured according to the ISO 13317-3 SediGraph method), at least one applied to the cover layer of the precoat, the paper is at 38 ° C and 90% relative humidity according to ASTM F1249 standard The water vapor permeability measured under tropical conditions is at most 150 g/m ² /24 h and preferably less than 100 g/m ² /24 h. The paper of claim 1 has a weight of no more than 10 g/m ² when dry, in particular less than 10 g/m ² . The paper of claim 2, the cover layer comprising a heat sealable polymer, or even a heat sealable polymer. The paper-like filler and the (or the like) finer filler have the same properties as in the paper of any one of claims 1 or 2. The paper of any of the preceding claims, wherein the shape factor of the plate-like filler particles is at least 40, more preferably at least 60. The paper of any one of the preceding claims, wherein the finer filler has a particle size of less than 2 microns measured according to the ISO 13317-3 SediGraph method of 95% by weight. The paper of any one of the preceding claims, wherein the plate-like filler is an inorganic filler. The paper of any of the preceding claims, wherein the finer filler is an inorganic filler. The paper of any one of the preceding claims, wherein the (s) plate filler is selected from the group consisting of kaolin and Talc and its mixtures. The paper of any of the preceding claims, wherein the (or more) finer filler is selected from the group consisting of kaolin, calcium carbonate, barium sulfate, vermiculite, titanium dioxide, and mixtures thereof. The paper of any of the preceding claims, wherein the (or less) finer filler is selected from the group consisting of kaolin. The paper according to any one of the preceding claims, wherein the dry weight of the platy filler is between 3% and 58% of the total dry weight of the precoat layer, and the weight of the platy filler is preferably greater than the finer filling. The weight of the agent. The paper of any of the preceding claims, wherein the finer filler has a dry weight between 3% and 58% of the total dry weight of the precoat. The paper according to any one of the preceding claims, wherein the percentage of the plate-like filler expressed by dry weight relative to the sum of the fillers expressed by dry weight is between 10% and 90%, preferably 40%. Between 90%, and more preferably between 60% and 90%. The paper of any one of the preceding claims, wherein the binder has a glass transition temperature T _{g of} less than or equal to 25 ° C and more preferably less than 10 ° C. The paper according to any one of the preceding claims, wherein the binder is selected from the group consisting of styrene-butadiene, styrene-acrylic acid, acrylic acid, butyl acrylate, butyl acrylate-styrene-acrylonitrile chemistry and the like mixture. A paper according to any one of the preceding claims, wherein the binder is selected from the group consisting of styrene-butadiene chemistries. The paper of any of the preceding claims, the binder is introduced in the form of a latex. A paper according to any one of the preceding claims, which comprises at least 15 dry parts and preferably more than 25 dry parts, more preferably 30 dry parts, by weight (100 parts) relative to the weight of the filler when dried. Adhesive. A paper according to any of the preceding claims, wherein the binder comprises a chemically non-polymeric polymer present in the cover layer. The paper of any of the preceding claims, the cover layer is substantially free of filler. The paper of any of the preceding claims, the cover layer being the only layer covering the precoat layer. A paper according to any of the preceding claims, the cover layer comprising one or more polymers selected from the group consisting of PVdC based or copolymers based on styrene-acrylic acid and mixtures thereof. A paper according to any one of the preceding claims, wherein the amount of the precoat layer is less than or equal to 12 g/m ² on a dry basis. A paper according to any of the preceding claims, comprising a printed layer on a face of the substrate opposite the face with the precoat and the cover layer. A paper according to any of the preceding claims, which has two identical precoats on its opposite side. The paper of any one of claims 1 to 25, the substrate having two pre-coatings of different nature on its opposite side. A paper according to any of the preceding claims, wherein a pore filling composition is applied to the substrate and the precoat layer is applied to the pore filling composition, the pore filling composition preferably being applied by a size press or a film press. . A paper according to any one of the preceding claims, wherein the fibrous substrate has a basis weight of between 25 and 180 g/m ² . The paper of any of the preceding claims, when the seal is carried out by a hot clip at 3 bar for 0.5 s, the paper is heat sealable, especially starting at 90 °C. The paper of any of the preceding claims, the paper having a final basis weight of between 45 and 200 g/m ² . A precoated paper suitable for the manufacture of a paper according to any one of claims 1 to 31, which has a water vapor permeability of at most 150 g/m ² at 38 ° C and 90% relative humidity according to ASTM F1249. /24h and preferably less than 100g/m ² /24h. If the pre-coated paper of claim 32 is applied, the pre-coated paper is not calendered. A package comprising the paper of any one of claims 1 to 33. The paper is heat sealed to itself as packaged in claim 34. A package according to any one of claims 34 and 35, which contains a food product. A method for producing a paper according to any one of claims 1 to 33, wherein the composition is applied to a fibrous substrate, the composition comprising a binder in the form of a latex and a plate-like filler having a shape factor of at least 15 A dispersion of a mixture of finer fillers having a particle size of 80% by weight of the finer filler is less than 2 μm. A method for producing a water vapor barrier paper according to any one of claims 1 to 33, wherein the barrier paper is water vapor measured under so-called tropical conditions of 38 ° C and 90% relative humidity according to ASTM F1249 standard. Permeability of up to 150 g/m ² /24 h, and heat sealable, wherein at least one cover layer comprising at least one thermoplastic film-forming polymer is applied in-line to the paper machine and the fibrous substrate, and wherein the pre-coating is applied in-line, after which The cover layer is applied to the precoat layer. The method of the above claim, the speed of paper production is greater than or equal to 300 m/min, preferably greater than or equal to 400 m/min, and even more preferably greater than or equal to 500 m/min. The method of any one of claims 38 or 39, wherein the pore-filling composition is applied to the fibrous substrate in-line prior to the application of any layer or precoat layer, preferably by a size press or film. Pressed by the press. An adjustment method in which a longitudinal sealing line of 330 mm per bag is heat sealed by a VFFS (vertical forming, filling and sealing) type of vertical packaging machine, especially at a manufacturing rate of 40 bags per minute or more. The paper obtained by the manufacturing method of any one of the items 37 to 40 is supplied to the object itself to package the object.