CA2956766A1 - Heat-sealing barrier paper - Google Patents

Abstract

The invention relates to a paper comprising: a fibrous substrate; a precoat including a binder and a mixture of lamellar filler(s) having a form factor of at least 15 and of finer filler(s) having a particle size, at a concentration of 80% by weight, of less than 2 µm (measured using the SediGraph technique according to ISO 13317-3); and at least one coating layer applied to the precoat, said paper having a water vapour permeability of at most 150 g/m2/24h and preferably less than 100g /m2/24h, measured according to ASTM F 1249 under so-called tropical conditions of 38°C and 90% relative humidity.

Description

Heat Seal Barrier Paper The present invention relates to the field of packaging papers.
Plastic films are widely used in flexible packaging because they have water vapor barrier properties necessary for the good preservation of perishable products or products with a limited shelf life.
Papers are materials made from fibers, usually cellulosic, therefore of plant origin. They are naturally porous and permeable to gas and can not, as such, be used for this application.
It is however known to associate papers with other materials (plastics, aluminum, ...) to obtain the necessary barriers to product packaging various and especially perishable goods In this case the paper substrate is subject to transformation operations which include for example the coating of layers of coating made of polymers in dispersion, the extrusion coating of polymers melted or laminating with plastic films or aluminum. The cost of this paper-based composite with barrier properties has become expensive.
US 2,653,870 A discloses a papermaking process packaging.
Packaging made from barrier papers manufactured online are described in application WO2011 / 056130. Online manufacturing is defined as the manufacturing on a single production tool with all the elements useful to realization of the paper.
However, the proposed barrier level is limited to measurement conditions not very restrictive (temperate, ie 25 C, 75% relative humidity). Level barrier is measured by a permeability to water vapor, a weak barrier signifying a permeability to high water vapor. It is known in the literature that conditions tropical 38 C, 90% rela.tive moisture) are much more severe than temperate conditions, and therefore the barrier measured under the conditions temperate is much weaker.
"Barrier paper" means a non-porous paper with a fibrous substrate covered with one or more layers, sufficiently tight steam of water to prevent its penetration into the packaging, into one quantity may affect the preservation of the product or the integrity of the product content to

2 The invention is particularly but not exclusively concerned with water vapor barriers having a water vapor permeability of from more 150 g / m2 / 24h and, preferably, less than 100 g / m2 / 24h, measured according to the ASTM standard F1249 in so-called tropical conditions of 38 C and 90% relative humidity.
It is advantageous that the barrier paper is also sealable so that of allow the formation of the packaging by welding the paper on itself.
For example, the manufacture of heat-sealable papers involves the depositing a covering layer of a thermosealing polymer on a substratum cellulose. Such a covering layer has a sticky power strong enough when not dry, and must be able to be dried completely before the paper is not wound on itself, otherwise the different turns of the coil between them.
The application of this covering layer is generally carried out line during one or more transformation steps, which makes it possible to have a good quality of coating, to benefit from paper at room temperature at moment of sleeping which allows the covering layer not to penetrate too much in the fibrous support, and to be able to adapt the passage time of the width in the ovens, at a speed for example of the order of 200m / min, so that the duration of exposure to these means of heating is sufficient to completely dry the layer of heat sealing liner.
US 2004/121079 Ai, WO 2010/052571 A2, US 2014/113080 Al and WO 2009/112255 A1 disclose papers that are processed offline.
Papers offering a barrier to water vapor and possibly heat sealants, are generally manufactured in the state of the art when operations of transformation and present standard layers of recovery from 10 to 30 g / m2 dry which are deposited in one or more thicknesses using different ways Sleeping (air knife, reverse engraving, blade or bar Meyer or any other fashion coating) or by applying a thick layer using a coating curtain.
The offline transformation of a paper to give it properties of barrier to water vapor and heat seal is so a step additional to the paper making that significantly increases its cost and which limit the development of paper in flexible packaging in favor of packaging by movies plastics. There is therefore an economic need to improve the productivity of the manufacture of barrier papers with water vapor and theimiles.

3 The invention relates to the development of a paper endowed, during its manufacture online, of vapor barrier properties and sealability. This paper barrier and thennellant can be used to make a packaging in welding the paper on itself.
Regardless of how the heat sealing layer is applied, in online or offline, there is the problem of facilitating the removal of the heat-sealing and more generally any covering layer, heat sealing or not, applied on a fibrous substrate.
It is generally desirable that the cover layer does not penetrate too deep in the fibrous substrate, to reduce the amount applied paper when this layer is polymer-based. In addition, a lower penetration of layer cover makes it easier to create a barrier film.
The use of a Yankee cylinder (Yankee cylinder) is a first solution to reduce surface porosity.
A second possibility is the use of a shell before any treatment of paper.
Another possibility is to predict the presence of a precoat to decrease the porosity of the paper.
Another possibility is to combine one or the other of the previous ones.
Some latex can be used in the formulation of the precoat hydrophobic and very filmogenic.
However, the hydrophobic character of the precoat can then pose a problem.
wetting problem when applying the covering layer, when this is aqueous, leading to a not perfectly homogeneous coverage of the substratum fibrous precoated by the covering layer, especially in the case of a process in line with a high speed of the sheet. In addition, the surface energy of the precoat must be sufficiently different from that of the overlay respecting the well known rules of wettability to reduce the risk of defects of wetting.
There remains, therefore, a need to respond satisfactorily to problem of the applicability of the covering layer.
The invention meets this need, according to one of its aspects, thanks to a paper comprising:

4 a fibrous substrate, a precoat comprising a binder and a mixture of filler (s) lamellar (s) of form factor of at least 15 and especially finer load (s) whose particle size is 80% by weight less than 2 μm (measured according to method Sedigraph 1S013317-3), at least one covering layer applied to the precoat, paper having a water vapor permeability of not more than 150 g / m2 / 24 hours and of preferably less than 100g / m2 / 24h, measured according to ASTM standard F1249 in of the so-called tropical conditions of 38 C and 90% relative humidity.
The presence, in the precoat according to this aspect of the invention, of a charge lamellar form factor of at least 15 and a particulate filler plus fine, especially non-lamellar, whose particle size at 80% by weight is less than 2! .tm (measured using Sedigraph IS013317-3 method), provides a level of fence relatively high, regardless of the hydrophobic nature or not of the binder.
It is known that lamellar fillers help to increase the effect fence thanks to the tortuosity they bring, as taught for example by the Imerys document Technical Guide, Pigments Far Paper, May 2008. The presence according to this aspect of the invention of at least one finer particulate filler, in particular not lamellar, increases this effect. An attempt at explanation is that this charge, by interfering between the lamellar particles, further hinders the movement of water molecules in particularly around lamellar particles. WO 2009/117040 A1 discloses lamellar charges of clay.
Due to the barrier effect related to the particular choice of charges present in the precoated, greater freedom exists as to the nature of the binder used.
It is thus possible to use in particular any paper binder without particular barrier property, which provides the double benefit a weak permeability to water vapor for precoat and good wettability with respect to the covering layer.
The invention makes it possible to have a reinforced barrier effect with the precoat, which who allows a reduction in the amount of topcoat to apply or, in quantity of equal overlap, allows to further increase the barrier level paper, which may be useful for papers that need to be vapor tight of water. The decrease in the amount of overlay required because of the power stronger barrier of the precoated paper, facilitates its drying and can make easier on coating of it during the online manufacture of paper.
The paper of the invention is preferably made on paper machine to go a fibrous substrate made of cellulose fibers and possibly fibers

5 synthetic.
Cellulose fibers are generally a mixture of short fibers and long fibers.
Additives such as bonding agents, resistance agents in the state wet, retention agents, or defoamers can be added.
The paper may also contain paper charges such as dioxide titanium, kaolin, calcium carbonate, talc, among others.
The paper is preferably a wrapping paper.
The invention also relates to a precoated paper suitable for manufacturing a barrier paper according to the invention as defined above, exhibiting permeability with water vapor of at most 150 g / m2 / 24h and preferably less than 100 g / m2 / 24h, according to the aforementioned standard. The precoated paper may be non-calendered.
The subject of the invention is also a precoat composition for the manufacture of a paper according to the invention, comprising a binder in the form of latex and a dispersion of a mixture of lamellar filler (s) of form factor of from minus 15 and finer charge (s) with a particle size of 80% by weight less than 2 μm.
The invention also relates to a package comprising a paper according to the invention, in particular heat-sealed on itself and containing for example a product food re.
The subject of the invention is also a process for producing a paper according to in which the composition of the invention is applied to a fibrous substrate precoating as defined above.
precoat The precoat may be identical to the overlay or be pigment layer as defined below.
The precoat is preferably composed of a mixture of at least one latex and fillers still sometimes called pigments.
US 4,018,647 A discloses latex examples.

WO 2016/016340

6 The latex according to the invention preferably has a Tg (temperature of glass transition) measured by ASTM E1356 less than 25 C and more preferentially less than 10 ° C. The latex may be chosen from natures latex styrene-butadiene, styrene-acrylic, acrylics, butyl-acrylate, butyl-acrylate-styrene-acrylonitrile, .... and more particularly among the emulsions of styrene-butadiene.
The level of latex is preferably at least 15 parts dry relative to dry loads (100 parts), preferably at least, or even more, of 25 and better 30 shares per 100 parts of charge.
The charges are preferably constituted by a mixture of charge (s) lamellar (s) and finer loads, especially non-lamellar.
The lamellar charge (s) are lamellar shaped particles having a Factor of cum (ratio between greater length and thickness) higher or equal to 15, more preferably at least 40 and even more preferably at least 60.
The precuhe comprises a binder and a mixture of lamellar filler (s) form factor of at least 15 and finer load (s), in particular not lamellar (s), whose particle size is 80% by weight less than 2 μm (measured according to the method Sedigraph 18013317-3).
To have a mixture of lamellar charge (s) and finer load (s) whose particle size at 80% by weight is less than 2 μm, the size of 80% particle in weight of filler (s) lamellar (s) may for example be greater than or equal to at 2 tim.
According to another example, less than 80% by weight of lamellar particles can to be inferior at 2 m.
In other words, to have finer charges than the charge (s) lamellar (s), the finer fillers can according to a first example present a size of particles smaller than that of lamellar charges with weight equivalent. According to a second example they can present a distribution in weight greater for the same particle size as the charges lamellar.
The finer fillers can be chosen from all other pigments used in stationery, which meet the required size requirements.
The percentage of lamellar charges in relation to the total charges can vary from 10 to 90%, preferably from 40 to 90% and even more preferably from 60 to 90%.

7 The lamellar fillers may be chosen for example from kaolin and the talc, and mixtures thereof.
Between 30% and 80% by weight of lamellar particles can be large less than or equal to 2um (measured according to the method SedigraphIS013317-3).
The particles of the lamellar filler (s) are particularly oriented substantially parallel to the surface of the substrate.
The particles of the finer fillers can be chosen from the calcium carbonate, barium sulfate, silica, titanium dioxide or their mixtures ... They are characterized by a particle size of 80% in weight less than 2 microns, measured according to the method Sedigraph1S013317-3 The finer fillers can be chosen from any other pigment, including kaolin, of a sufficient fineness, in particular by a size of 95% particle in weight less than 2 microns, measured according to the method Sedigraph 1S013317-3.
The binder is preferably chosen from the abovementioned latexes but other binders or co-binders such as PVOH, starch, CMC ... can be used. The binder can have a polymer of a chemical nature not present in the covering layer.
Cover layer The polymers used to obtain the vapor barrier and the heat sealing are preferably chosen from polymers or copolymers based on PVdC (polyvinylidene chloride) or acrylic.
These polymers are applied pure or mixed with fillers. By pure is meant without particulate charge. We can possibly add other polymer dispersion products such as pH control agents, agents rheological techniques (viscosising for example), anti-foam agents, wettability, The use of fillers in the covering layer can in particular help reduce the risk of sticking the coils of the coil together.
Manufacturing Preferably, the cover layer is applied in line.
The invention makes it possible to obtain good levels of barrier to water vapor with covering layer weights not exceeding 10g / m2 in sec.

8 Despite the relatively high speed of advance of paper imposed by a industrial paper-making machine, order for example 400 ri / mn, the coating of a composition intended to form the recovery heat sealing is possible, subject to using a drying capacity sufficient for dry the layer before the winding operation. In particular, a weight of layer of relatively low recovery can facilitate drying online, while bringing sufficient barrier properties.
The online process increases productivity by eliminating handling operations related to offline processing.
After drying the fibrous substrate, the paper sheet may pass over cylinder yankee cylinder (English) to improve the surface condition of the sheet and thus the distribution of the first layer.
The sheet can then be processed in size-press or other equipment of the same type. To avoid the excessive penetration of the precoat in the fibrous support, a pigment composition can be previously used to make the mouth-porage.
This pore-filling composition can contain up to 20 parts per relative to the dry charges of binder, such as latex, of a styrene chemical nature butadiene for example, and up to 20 parts dry relative to the dry pigments of co-binders like starch, for example.
This composition preferably contains fillers that are large generally less than 2 microns. These charges can be chosen between others, among kaolins or calcium carbonates or mixtures thereof.
The precoat is applied to the support thus treated using any which sleeping techniques that can be encountered on the machines to paper. This can include blade coating, rotogravure, reverse engraving or sleeping at the bar of Meyer. The precoat is deposited with a weight of dry layer preferably between 4 and 12 g / m2.
This precoat is then dried without contact by one or more ovens infra-red and / or one or more hot air ovens.
It is not necessary to have a very high level of satin the application of the covering layer. A level of 150 seconds Bekk is sufficient (measured according to ISO 5627).

9 The water-vapor barrier and heat-sealing layer is applied by coating using any of the sleeping that can be found on paper machines. This can be for example a blade coating, rotogravure, reverse engraving or bar coatings from Meyer.
The top layer is deposited with a dry coat weight of preference of 10g / m2 maximum.
This covering layer is then sufficiently dried, to avoid that the turns do not stick at the winding reel, using one or many infrared ovens and / or one or more hot air ovens.
A coating on the opposite side can be made to reinforce the barrier and / or to provide other features such as printability, correction of curl, The paper thus produced can optionally be calendered online for reduce the surface roughness before being rolled up.
The final basis weight of the paper may be between 45 and 200 g / m2.
The water vapor barrier measured according to ASTM F1249 at 38 C and 90% relative humidity is less than 150g / m2 / 24h, and preferentially to 100 g / m2 / 24h.
Example 1 A 55g / m2 fibrous support is produced on a paper machine operating at 400m / min. The paper machine is equipped with a roller frictionner placed before the size-press.
The fibrous support is first rubbed and then processed online on its two sides by size-press with a fungi pigment composition, containing 100 dry parts of Amazon Premium type kaolin (Cadarn), and a blend of Merifilm starch 104 (Tate & Lyle) and latex type DL950 (Dow) up to 20 dry parts per report to dry kaolin The treatment applied is 5g / m2 dry in total.
It is then coated using a Meyer bar coater with a precoating formulation containing a mixture of lamellar fillers and loads finer particulate matter and a chemical latex styrene-butadiene Tg, --- 7 C
(DL950 from Dow Chemical) and dried without contact on an infrared oven then an oven hot air. It is then wound into a reel without further processing. The weight dry of the applied precoat is 7g / m2 and its formulation is given in the table below :
Material Reference / Nature Suppliers Parts%
mass Topsperse GX-N Dispersant CORTEX 0,2 0,2 Capim NP Kaolin 1 IMERYS 60.0 45.5 (lamellar charge) Amazon Prime Kaolin CADAM 40.0 30.4 (finer load) Bacote 20 Crosslinker QUARRECHIM 1,5 1,1 DL950 / Latex Styrene-Butadiene Latex styrene-butadiene Tg 7 C DOW 30.0 22.8 Tg 7 C
The particle size at 97% by weight of Amazon Premium, measured according to the Sedigraph method IS013317-3, is less than 2 microns.
The Capim NP Particle Form Factor is 28.
The water vapor barrier is measured by a Mocon brand, Permatran 3/61 according to ASTM F1249 at 38 C and 90% humidity on to determine the barrier contribution of this precoat. It is measured at 334 +/-13g / m2 / 24h. After coating the covering layer, a fence less than 150 g / m2 / 24h.
Example 2 The fibrous support is first rubbed and then processed online on its two sides by size-press with a pigment-containing filler composition containing 100 dry parts of Premium Amazon kaolin (Cadarn) and a mixture of Merifilm starch 104 (Tate & Lyle) and latex type DL950 (Dow) up to 20 dry parts per report to dry kaolin. The treatment applied is 5g / m2 dry in total.
It is then coated using a Meyer bar coater with a formulation containing a mixture of lamellar fillers and fillers particulates more fines and a latex of chemical nature styrene-butadiene of Tg = 7 C (Dow DL950 Chemical) and dried without contact on an infra-red oven and then an air oven hot. It is then wound into a reel without further processing. The dry weight of the precoat applied is of 7g / m2 and its formulation is given in the table below:
Material Reference / Nature Suppliers Parts%
mass Topsperse GX-N Dispersant COATEX 0,2 0,2 Capim NP Kaolin IMERYS 60.0 45.5 (lamellar charge) Hydrocarb 95 Calcium carbonate OMYA 40.0 30.4 (finer load) Bacote 20 Crosslinker QUARRECHIM 1,5 1,1 DL950 / Latex - Latex styrene-butadiene styrene-butadiene Tg 7 C DOW 30.0 22.8 Tg 7 C
The particle size at 95% by weight of Hydrocarb 95, measured according to the Sedigraph method 1S013317-3, is less than 2 microns.
The water vapor barrier is measured by a Mocon brand, Permatran 3/61 according to ASTM F1249 at 38 C and 90% humidity on to determine the barrier contribution of this precoat. It is measured at 315 +/-9g / m2 / 24h, After coating of the covering layer, one obtains a fence less than 150 g / m2 / 24h.
Example 3 A paper is produced online under the same conditions as in the example 1. But after removal of the precoat, it is coated in line with a layer of coating consisting of a dispersion of PVdC copolymer (Diofan A297 from Solvay), and dried without contact on an infrared oven and then an air oven hot. It is then rolled into a reel without further processing and no gluing between turns is not observed.
The dry weight of the covering layer is 6.5 g / m2.
The water vapor barrier is measured by a Mocon brand, Permatran 3/61 according to ASTM F1249 at 38 C and 90% humidity relative.
It is measured at 21.0 +/- 2.4g / m2 / 24h.
The seal is then simulated on a laboratory heat sealer.
sticking the coated face of the covering layer to itself at 110 C, under 3bars and for 0.5 seconds. Then the force needed to detach the papers pasted on 15min wide samples are then measured at an angle of 90 degrees according to the Tappi T540 standard at a speed of 100mm / min.
A sealing force of 3.5N / 15mm is obtained.
The invention is not limited to the examples described.
In summary, the invention may have one or more of the features following advantages:
the weight of the covering layer does not exceed 10 g / m 2 in dry, especially is strictly less than 10g / rd, the covering layer comprises or consists of a polymer heat sealable, - the lamellar load (s) and the finer load (s) are of same nature, - the form factor of the lamellar filler particles is at least 40, more preferably at least 60, - the finer load (es) are non-lamellar (s), - the finer load (s) are lamellar (s), the finer filler (s) have a particle size of 95% by weight, less than 2 microns, measured according to the method Sedigraph 1SO 13317-3, the lamellar charge or fillers are mineral, - the finer load (s) are mineral (s), the lamellar charge (s) are chosen from among the kaolins and the talc and their mixtures, - the finest load (s) are chosen from among the kaolins, carbonate of calcium, barium sulphate, silica, titanium dioxide and their mixtures, - the finest load (s) are chosen from among the kaolins, the dry weight of the lamellar filler (s) is between 3 and 58% by weight total dry weight of the precuhee, the weight of the lamellar filler (s) being higher preference to that of the finer loads, - the dry weight of the finer load (s) is between 3 and 58% of the weight dry total precoat, - the percentage of lamellar filler (s), expressed in dry weight, relative to in total of the charges, expressed in dry weight, is between 10 and 90%, preferably between 40 and 90% and even more preferably between 60 and 90%, the binder has a lower glass transition temperature Tg or equal at 25 ° C and more preferably below 10 ° C, the binder is chosen from latices of a styrene-butadiene chemical nature, styrene-acrylic, acrylics, butyl-acrylate, butyl-aryl-styrene-acrylonitrile, and their mixtures, the binder is chosen from latices of a styrene-butadiene chemical nature, the binder is introduced in latex form, the precoat has at least 15 parts by weight of binder relative to the weight in dry charges (100 parts), and preferentially of more than 25, better 30 shares the binder comprises a polymer of a chemical nature not present in the covering layer, the covering layer is substantially free of charge, the covering layer is the single layer covering the precoat, the covering layer comprises one or more polymers chosen among the copolymers based on PVdC or styrene-acrylic and their mixtures, the amount of precoat is less than or equal to 12 g / m 2 by dry weight, the paper has a printability layer on the face of the substrate opposite to that carrying the precoat and the covering layer, the substrate has two identical pre-layers on its opposite faces, the substrate has two precursors of different natures on its faces opposite, a filler composition is applied to the substrate, and the precoat is applied to the filler composition, the filler composition being preferably applied by size-press or film-press, gram-14e of the fibrous substrate is between 25 and 180 g / m2, - the paper isimposable, especially from 90 C, when the sealing is carried out on hot tongs, under 3 bar and during 0.5s, the water vapor permeability of the barrier paper is less than 100 g / m2 / 24h.

between 30% and 80% by weight of lamellar particles are lower or equal to 21 μm (measured according to Sedigraph Method 1S013317-3), the paper is thermally sealable, in particular on itself, at a rate of manufacture greater than or equal to 40 bags per minute, on machines packing Vertical Forms, Fill and Seal (VFFS), along lines of sealing lengths of 330 mm per bag, - the paper is heat-sealable on itself with a sealing force greater than or equal to 2 N / 15rnm, measured at an angle of 90 degrees standard Toppi T540 at a speed of 100mrn / min, when sealing is done on pliers hot, under 3 bars, and for 0.5 s, the temperature of the fibrous substrate during the application of the precoat is greater than or equal to 50 C, the temperature of the fibrous substrate during the application of the recovery is greater than or equal to 70 C, the final grammage of the paper is between 45 and 200 g / m2.
The expression bearing one must be understood as being synonymous with comprising at least one.

Claims (37)

5 1. Paper comprising:
a fibrous substrate, a precoat comprising a binder and a mixture of lamellar filler (s) shape factor of at least 15 and finer load (s), in particular not lamellar (s), the particle size of which is 80% by weight less than 2 μm (measured according to the method Sedigraph ISO13 3 17-3), at least one covering layer applied to the precoat, paper having a water vapor permeability of not more than 150 g / m2 / 24 hours and of preferably less than 100g / m2 / 24h, measured according to ASTM standard F1249 in of the tropical conditions of 38 ° C and 90% relative humidity 2. Paper according to claim 1, the weight of the covering layer does not not exceeding 10g / m2 in dry, especially being strictly less than 10 g / m2. 3. Paper according to claim 2, the covering layer comprising a heat-sealable polymer, or even consisting of a polymer sealable. 4. Paper according to one of claims 1 or 2, the load (s) lamellar (s) and the finer (s) load (s) being of the same nature. The paper according to any one of the preceding claims, wherein the form particles with lamellar charge (s) being at least 40, more preferably at least 60. Paper according to any one of the preceding claims, wherein the finer load (s) having a particle size of 95% lower by weight at 2 microns, measured according to Sedigraph method ISO 13317-3. The paper of any one of the preceding claims, the one or more lamellar charges being mineral. Paper according to any one of the preceding claims, wherein the finer load (s) being mineral (s). The paper of any one of the preceding claims, the one or more lamellar filler (s) being selected from kaolin and talc and their mixtures. The paper of any one of the preceding claims, the one or more finer load (s) being chosen from kaolins, carbonate of calciurn, sulphate barium, silica, titanium dioxide and mixtures thereof. Paper according to any one of the preceding claims, wherein the finer load (s) being chosen among the kaolins. The paper of any one of the preceding claims, the dry weight lamellar filler (s) being between 3 and 58% of the total dry weight of the precoat, the weight of lamellar filler (s) being preferably greater than that of more charges fines. 13. Paper according to any one of the preceding claims, the dry weight of finer charge (s) being between 3 and 58% of the total dry weight of the precoat. The paper according to any one of the preceding claims, the percentage of lamellar filler (s), expressed as dry weight, relative to total fillers, expressed in dry weight, being between 10 and 90%, preferably between 40 and 90% and even more preferably between 60 and 90%. 15. Paper according to any one of the preceding claims, the binder having a glass transition temperature Tg less than or equal to 25 ° C and more preferably below 10 ° C. 16. Paper according to any one of the preceding claims, the binder being selected from the latex of chemical nature styrene-butadiene, styrene acrylic, acrylics, butyl acrylate, butyl-aryl-styrene-acrylonitrile, and mixtures thereof. 17. Paper according to any one of the preceding claims, the binder being selected from styrene-butadiene chemical latexes. 18. Paper according to any one of the preceding claims, the binder being introduced in the form of latex. 19. Paper according to any one of the preceding claims, comprising in the precoat, at least 15 parts by weight of binder relative to the weight in dry charges, (100 parts) and preferentially more than 25, better 30 parts. 20. Paper according to any one of the preceding claims, the binder comprising a polymer of a chemical nature not present in the recovery. 21. Paper according to any one of the preceding claims, the layer of covering being substantially without load. 22. Paper according to any one of the preceding claims, the layer covering being the single layer covering the precoat. 23. Paper according to any one of the preceding claims, the layer covering comprising one or more polymers chosen from copolymers based on PVdC or styrene-acrylic and mixtures thereof. 24. Paper according to any one of the preceding claims, the quantity pre-layer being less than or equal to 12 g / m 2 by dry weight. 25. Paper according to any one of the preceding claims, comprising a printability layer on the face of the substrate opposite to that carrying the precoated and the covering layer. 26. Paper according to any one of the preceding claims, the substrate bearing two identical precolors on its opposite faces. 27. Paper according to any one of claims 1 to 25, the substrate wearing two precolors of different natures on its opposite faces. 28. Paper according to any one of the preceding claims, a mouthpiece composition being applied to the substrate, and the precoat being applied on the filler composition, the filler composition being applied of preferably by size-press or film-press. 29. Paper according to any one of the preceding claims, the the weight of the fibrous substrate being between 25 and 180 g / m2. 30. Paper according to any one of the preceding claims, the paper being heat-sealable, notannnent from 90 ° C, when sealing is performed on hot tongs. under 3 bars and during 0.5s. 31. Paper according to any one of the preceding claims, the final basis weight of the paper being between 45 and 200g / m2. 32. Precooked paper suitable for the manufacture of paper as defined in any one of claims 1 to 31 having a permeability to water vapour of at most 150g / m2 / 24h and preferentially less than 100g / m2 / 24h according to the standard ASTM F-1249 at 38 ° C and 90% relative humidity. 33. Precoated paper according to claim 32, the precured paper being non calendered. 34. Package comprising a paper as defined in one of claims 1 at 33. 35. Packaging according to claim 34, the paper being heat-sealed on itself even. 36. Package according to any one of claims 34 or 35, containing a food product. 37. A method of manufacturing a paper according to any one of Claims 1 to 33, wherein a fiber substrate is applied to a fibrous substrate.
composition comprising a binder in latex form and a dispersion of a mixture of filler (s) lamellar (s) of form factor of at least 15 and finer load (s) whose size particles at 80% by weight is less than 2 microns.