Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H27/00—Special paper not otherwise provided for, e.g. made by multi-step processes
  • D21H27/10—Packing paper
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65B—MACHINES, APPARATUS OR DEVICES FOR, OR METHODS OF, PACKAGING ARTICLES OR MATERIALS; UNPACKING
  • B65B9/00—Enclosing successive articles, or quantities of material, e.g. liquids or semiliquids, in flat, folded, or tubular webs of flexible sheet material; Subdividing filled flexible tubes to form packages
  • B65B9/10—Enclosing successive articles, or quantities of material, in preformed tubular webs, or in webs formed into tubes around filling nozzles, e.g. extruded tubular webs
  • B65B9/20—Enclosing successive articles, or quantities of material, in preformed tubular webs, or in webs formed into tubes around filling nozzles, e.g. extruded tubular webs the webs being formed into tubes in situ around the filling nozzles
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H19/00—Coated paper; Coating material
  • D21H19/10—Coatings without pigments
  • D21H19/14—Coatings without pigments applied in a form other than the aqueous solution defined in group D21H19/12
  • D21H19/20—Coatings without pigments applied in a form other than the aqueous solution defined in group D21H19/12 comprising macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H19/00—Coated paper; Coating material
  • D21H19/10—Coatings without pigments
  • D21H19/14—Coatings without pigments applied in a form other than the aqueous solution defined in group D21H19/12
  • D21H19/20—Coatings without pigments applied in a form other than the aqueous solution defined in group D21H19/12 comprising macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H19/22—Polyalkenes, e.g. polystyrene
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H19/00—Coated paper; Coating material
  • D21H19/36—Coatings with pigments
  • D21H19/38—Coatings with pigments characterised by the pigments
  • D21H19/385—Oxides, hydroxides or carbonates
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H19/00—Coated paper; Coating material
  • D21H19/36—Coatings with pigments
  • D21H19/38—Coatings with pigments characterised by the pigments
  • D21H19/40—Coatings with pigments characterised by the pigments siliceous, e.g. clays
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H19/00—Coated paper; Coating material
  • D21H19/36—Coatings with pigments
  • D21H19/44—Coatings with pigments characterised by the other ingredients, e.g. the binder or dispersing agent
  • D21H19/54—Starch
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H19/00—Coated paper; Coating material
  • D21H19/36—Coatings with pigments
  • D21H19/44—Coatings with pigments characterised by the other ingredients, e.g. the binder or dispersing agent
  • D21H19/56—Macromolecular organic compounds or oligomers thereof obtained by reactions only involving carbon-to-carbon unsaturated bonds
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H19/00—Coated paper; Coating material
  • D21H19/36—Coatings with pigments
  • D21H19/44—Coatings with pigments characterised by the other ingredients, e.g. the binder or dispersing agent
  • D21H19/56—Macromolecular organic compounds or oligomers thereof obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H19/58—Polymers or oligomers of diolefins, aromatic vinyl monomers or unsaturated acids or derivatives thereof
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H19/00—Coated paper; Coating material
  • D21H19/36—Coatings with pigments
  • D21H19/44—Coatings with pigments characterised by the other ingredients, e.g. the binder or dispersing agent
  • D21H19/62—Macromolecular organic compounds or oligomers thereof obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H19/00—Coated paper; Coating material
  • D21H19/80—Paper comprising more than one coating
  • D21H19/82—Paper comprising more than one coating superposed
  • D21H19/826—Paper comprising more than one coating superposed two superposed coatings, the first applied being pigmented and the second applied being non-pigmented
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H19/00—Coated paper; Coating material
  • D21H19/80—Paper comprising more than one coating
  • D21H19/84—Paper comprising more than one coating on both sides of the substrate
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H23/00—Processes or apparatus for adding material to the pulp or to the paper
  • D21H23/02—Processes or apparatus for adding material to the pulp or to the paper characterised by the manner in which substances are added
  • D21H23/22—Addition to the formed paper
  • D21H23/24—Addition to the formed paper during paper manufacture
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H27/00—Special paper not otherwise provided for, e.g. made by multi-step processes
  • D21H27/16—Pure paper, i.e. paper lacking or having low content of contaminants

Definitions

• 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 proper preservation of perishable products or having a limited life.
• Papers are materials made from fibers, usually cellulosic, therefore of plant origin. They are naturally porous and gas permeable and can not, as such, be used for this application.
• US 2,653,870 A discloses a method of manufacturing wrapping paper.
• the proposed barrier level is limited to mild measurement conditions (temperate, i.e. 25 ° C, 75% relative humidity).
• the barrier level is measured by permeability to water vapor, a low barrier signifying high water vapor permeability. It is known in the literature that "tropical" conditions (i.e. 38 ° C, 90% relative humidity) are much more severe than temperate conditions, and therefore the barrier measured under temperate conditions is much lower.
• carrier paper is meant a non-porous paper, having a fibrous substrate coated with one or more layers, sufficiently vapor-tight to prevent penetration thereof into the package. in an amount that may affect the preservation of the product or the integrity of the product contained therein.
• the invention is particularly, but not exclusively, concerned with water vapor barrier papers having a water vapor permeability of at most 150 g / m 2 / 24h and, preferably, less than 100 g / m 2 / 24h, measured according to ASTM F1249 in so-called tropical conditions of 38 ° C and 90% relative humidity.
• barrier paper is also heat sealable, to allow the formation of the package by welding the paper on itself.
• heat-sealable papers involves, for example, the deposition of a covering layer of a heat-sealing polymer on a cellulosic substrate.
• a covering layer has a rather strong stickiness when not dry, and must be able to be completely dried before the paper is wound on itself, otherwise the different turns of the coil will stick together.
• this covering layer is generally performed offline during one or more processing steps, which makes it possible to have a good quality of coating, to benefit from paper at room temperature at the time of coating. which allows the covering layer not to penetrate too much into the fibrous support, and to be able to adapt the passage time of the width in the furnaces, at a speed for example of the order of 200 m / min, so that the duration exposure to these heating means is sufficient to completely dry the heat-sealing overcoat layer.
• Papers offering a water vapor barrier and possibly heat-sealing are generally manufactured in the state of the art during processing operations and have standard covering layers of 10 to 30 g / m 2 dry which are deposited in one or more thicknesses by means of different coating means (air knife, reverse etching, Meyer blade or bar or any other coating method) or by the application of a thick layer to the coating. using a curtain bed.
• the invention relates to the development of a paper endowed, during its manufacture online, water vapor barrier properties and heat sealability.
• This barrier paper and heat sealant can be used to make a package by welding the paper on itself.
• the invention aims, in a first aspect, to meet this need and it achieves this through a method of manufacturing a water vapor barrier paper and heat sealable in which is applied online on the machine to paper and on a fibrous substrate at least one covering layer comprising at least one thermoplastic film-forming polymer.
• the invention provides good levels of barrier to water vapor even with a covering layer of weight not exceeding 1 Og / m 2 by dry weight, in particular strictly less than 10 g / m 2.
• This aspect of the invention is based on the observation that despite the relatively high speed of advance of the paper imposed by an industrial papermaking machine, of the order of eg 400 m / min, the coating in line of a The composition intended to form a heat-sealing covering layer is possible, provided that sufficient drying capacity is used to dry the layer prior to the winding operation.
• a relatively low coverage layer weight can facilitate on-line drying, while providing sufficient barrier properties.
• the invention therefore makes it possible, by means of an on-line method, to increase productivity by eliminating handling operations related to off-line processing and by reducing waste rates.
• the cover layer It is generally desirable for the cover layer not to penetrate too deeply into the fibrous substrate to reduce the amount applied to the paper when this layer is polymer-based. In addition, less penetration of the covering layer makes it easier to create a barrier film.
• the use of a Yankee cylinder (Yankee cylinder) is a first solution to reduce the surface porosity.
• a second possibility is the use of a calender before any paper treatment.
• Another possibility is to provide the presence of a precoat to reduce the porosity of the paper.
• This precoat may however not be present, and the covering layer may be applied to the fibrous substrate directly or after application of a filler layer.
• Another possibility is to combine one or the other of the previous ones.
• Some hydrophobic and highly hydrophobic latexes can be used in the precoat formulation.
• the hydrophobic character of the precoat layer can then pose a wettability problem when the covering layer is applied, when the latter is aqueous, resulting in a non-perfectly homogeneous covering of the fibrous substrate precoated by the covering layer, especially in the case of an in-line process with a high speed of the sheet.
• the surface energy of the precoat must be sufficiently different from that of the covering layer while respecting the well known rules of wettability to reduce the risk of wetting defects.
• lamellar fillers contribute to increase the barrier effect thanks to the tortuosity that they bring, as taught for example the document Imerys Technical Guide, Pigments for Paper, May 2008.
• the presence according to this aspect of the The invention of at least one finer particulate filler, in particular non-lamellar, increases this effect.
• This charge by interfering between the lamellar particles, further hinders the movement of the water molecules in particular around lamellar particles.
• WO 2009/117040 A1 discloses lamellar clay fillers.
• the invention makes it possible to have a reinforced barrier effect with the precoat, which allows a reduction in the amount of covering layer to be applied or, with an equal amount of covering layer, makes it possible to further increase the barrier level of the paper, This may be useful for papers that need to be watertight. Decreasing the amount of overlay required because of the higher barrier strength of the precoated paper makes it easier to dry and can make it easier to coat when paper is made online.
• the paper of the invention is preferably made on a paper machine from a fibrous substrate consisting of cellulose fibers and optionally synthetic fibers.
• Cellulose fibers are generally a mixture of short fibers and long fibers.
• Additives such as sizing agents, wet strength agents, retention agents, or defoamers may be added.
• the paper may also contain paper stocks such as titanium dioxide, kaolin, calcium carbonate, talc, among others.
• the paper is preferably a wrapping paper.
• the invention also relates to a paper obtained by the process according to the invention.
• the subject of the invention is also a packaging method in which an article is packaged by heat-sealing the paper obtained by the method according to the invention on itself, in particular at a production rate greater than or equal to 40 bags per minute, on Vertical Form, Fill and Seal (VFFS) packaging machines, along longitudinal sealing lines of 330 mm per bag.
• VFFS Vertical Form, Fill and Seal
• the precoat when present, may be identical to the covering layer or be a pigment layer as defined below.
• the precoat is preferably composed of a mixture of at least one latex and fillers still sometimes called "pigments".
• the latex according to the invention preferably has a Tg (glass transition temperature) measured according to ASTM E1356 below 25 ° C and more preferably below 10 ° C.
• the latex may be chosen from the following types of chemical latex: styrene-butadiene, styrene-acrylic, acrylics, butyl-acrylate, butyl-acrylate-styrene-acrylonitrile, and more particularly from styrene-butadiene emulsions.
• the latex content is preferably at least 15 parts dry relative to dry charges (100 parts), preferably at least, or more than 25 and preferably 30 parts per 100 parts of load.
• the fillers preferably contain lamellar fillers and are preferably constituted by a mixture of lamellar filler (s) and finer fillers, in particular non-lamellar fillers.
• the lamellar filler (s) are lamellar particles having a form factor (greater length to thickness ratio) greater than or equal to 15, more preferably at least 40 and even more preferably at least 60 .
• the precoat may comprise at least one lamellar filler of form factor of at least 15 and preferably a mixture of lamellar filler (s) of form factor of at least 15 and filler (s) finer (s), especially non-lamellar (s), whose particle size at 80% by weight is less than or equal to 2 ⁇ , measured by Sedigraph method ISO 13317-3.
• the particle size at 80% ) by weight of filler (s) lamellar (s) may for example be greater than 2 ⁇ .
• less than 80% by weight of lamellar particles may be less than or equal to 2 ⁇ m.
• the finer fillers may, according to a first example, have a smaller particle size than that of lamellar fillers with an equivalent weight distribution. According to a second example, they may have a greater weight distribution for the same particle size as that of the lamellar fillers.
• the finer fillers can be chosen from all the other pigments used in the paper industry, which satisfy the required size requirements.
• the percentage of lamellar charges with respect to the total charges can vary from 10 to 90%, preferably from 40 to 90% and even more preferably from 60 to 90%.
• the lamellar fillers may be chosen for example from kaolin and talc, and mixtures thereof.
• lamellar particles may be smaller than or equal to 2 ⁇ m (measured according to Sedigraph method ISO 13317-3).
• the particles of the lamellar fillers are in particular oriented substantially parallel to the surface of the substrate.
• the particles of the finer fillers may be chosen from calcium carbonate, barium sulfate, silica, titanium dioxide or mixtures thereof. They are characterized by a particle size at 80% by weight less than at 2 microns, measured according to Sedigraph method ISO 13317-3
• the finer fillers may also be chosen from any other pigment, including kaolin, of sufficient fineness, especially with a particle size of 95% by weight less than 2 microns, measured according to Sedigraph method ISO 13317-3.
• the binder is preferably chosen from the abovementioned latices but other binders or co-binders such as PVOH, starch, CMC. can be used.
• the binder may comprise a polymer of a chemical nature not present in the covering layer.
• the polymers used to obtain the vapor barrier and the heat seal are preferably chosen from polymers or copolymers based on PVdC (polyvinylidene chloride) or acrylic.
• polymers are applied pure or mixed with fillers.
• pure is meant without particulate load.
• fillers in the covering layer can in particular help reduce the risk of bonding the coils of the coil together.
• the paper sheet After drying the fibrous substrate, the paper sheet can pass on a Yankee cylinder to improve the surface state of the sheet and thus the distribution of the first layer.
• the sheet can then be processed in size-press or any other equipment of the same type.
• a pigment composition can be used beforehand in order to make "filler".
• This pore-filler composition can contain up to 20 parts in dry relative to the binder dry charges such as latex, of styrene-butadiene chemical nature for example, and up to 20 parts in dry relative to the dry pigments of co-binders such as starch for example.
• This composition preferably contains fillers that are generally less than 2 microns in size. These fillers may be chosen, among others, from kaolin or calcium carbonates or mixtures thereof.
• the precoat is applied to the support thus treated using any of the coating techniques that may be encountered on the paper machines. This may include a blade coating, rotogravure, reverse_gravure or a coating at Meyer's bar.
• the precoat is deposited with a dry layer weight of preferably between 4 and 12 g / m 2 .
• This precoat is then dried without contact by one or more infrared ovens and / or one or more hot air ovens.
• a level of 150 seconds Bekk is sufficient (measured according to ISO 5627).
• the water-vapor barrier and heat-sealing coating is coated by any of the coating techniques that can be found on paper machines. This can be for example a sleeping Blade, Rotogravure, Reverse Etching or Meyer Bar Coating.
• the covering layer is deposited with a dry layer weight preferably of 10 g / m 2 maximum.
• This covering layer is then sufficiently dried, to prevent the turns sticking at the winding reel, using one or more 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, curl correction, ....
• the paper thus produced can optionally be calendered in line to reduce the surface roughness before being rolled up.
• the final basis weight of the paper may be between 45 and 200 g / m 2 .
• the barrier to water vapor measured according to ASTM F1249 at 38 ° C and 90% relative humidity is less than 150g / m 2 / 24h, and preferably to 100g / m 2 / 24h.
• a fibrous support of 55 g / m 2 is produced on a paper machine operating at 400 m / min.
• the paper machine is equipped with a Yankee roller placed before the size-press.
• the fibrous support is firstly rubbed and then treated in line on both sides by size-press with a filler-containing pigment composition, containing 100 dry parts of kaolin type Amazon Premium (Cadam), and a mixture of starch Merifim 104
• the dry weight of the precoat applied is 7g / m 2 and its formulation is given in the table below: Material Reference / Nature Suppliers Mass%
• the Capim NP Particle Form Factor is 28.
• the water vapor barrier is measured by a Mocon brand apparatus, Permatran 3/61 type according to ASTM F1249 at 38 ° C and 90% relative humidity to determine the barrier contribution of this precoat. It is measured at 334 +/- 13g / m 2 / 24h. After coating of the covering layer, a barrier of less than 150 g / m 2 / 24h is obtained.
• a fibrous support of 55 g / m 2 is produced on a paper machine operating at 400 m / min.
• the paper machine is equipped with a Yankee roller placed before the size-press.
• the fibrous support is firstly rubbed and then treated in line on both sides by size-press with a filler-containing pigment composition containing 100 dry parts of kaolin type Amazon Premium (Cadam) and a mixture of starch Merifilm 104 (Tate & Lyle). ) and latex type DL950 (Dow) to 20 dry parts relative to the dry kaolin.
• the applied treatment is 5g / m 2 dry in total.
• the particle size at 95% by weight of Hydrocarb 95 measured according to the Sedigraph IS013317-3 method, is less than 2 microns.
• the water vapor barrier is measured by a Mocon brand apparatus, Permatran 3/61 type according to ASTM F1249 at 38 ° C and 90% relative humidity to determine the barrier contribution of this precoat. It is measured at 315 +/- 9g / m 2 / 24h. . After coating of the covering layer, a barrier of less than 150 g / m 2 / 24h is obtained.
• a paper is produced online under the same conditions as in Example 1. But following the removal of the precoat, it is coated in line with a covering layer consisting of a dispersion of PVdC copolymer (Diofan A297 Solvay), and dried without contact on an infrared oven and then a hot air oven. It is then wound into a reel without further processing and no gluing between turns is observed.
• the dry weight of the covering layer is 6.5 g / m 2 .
• the water vapor barrier is measured by a Mocon brand apparatus, Permatran 3/61 type according to ASTM F1249 at 38 ° C and 90% relative humidity. It is measured at 21.0 +/- 2.4g / m 2 / 24h.
• the seal is then simulated on a lab heat sealer by gluing the coated side of the cover layer to itself at 110 ° C, under 3bar and for 0.5 seconds. Then the force required to detach the papers stuck on 15mm wide samples is then measured at a 90 degree angle 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.
• the invention may have the following advantageous characteristics, alone or in combination:
• a precoat is applied in line before the application of the covering layer to the precoat.
• the speed of production of the paper is greater than or equal to 300 m / min, better still greater than or equal to 400 m / min, more preferably greater than or equal to 500 m / min,
• a filler composition is applied in line on the fibrous substrate before the application of any in-line layer or precoat, the filler composition being preferably applied by size-press, or by press film,
• the process comprises at least one in-line drying step and then an in-line winding step, the heating power during the drying step being sufficient for the covering layer to be sufficiently dry during the winding step so that the turns of the coil do not stick together,
• the paper is brought during the drying of the fibrous substrate, before any surface treatment, in particular coating, in contact with a fric-tioning cylinder,
• the paper is fed during drying of the covering layer in an area where the drying takes place without contact, in particular using at least one infrared ramp and / or hot air heating,
• the precoat has at least one lamellar charge of form factor of at least 15 and preferably a mixture of lamellar filler (s) of form factor of at least 15 and filler (s), in particular, more (s), in particular non-lamellar (s), whose particle size at 80% by weight is less than or equal to 2 ⁇ , measured by the Sedigraph method IS013317-3,
• the form factor of the lamellar particles is at least 40, more preferably at least 60,
• the filler (s) which are more refined have a particle size of 95% by weight less than 2 microns,
• the lamellar charge or fillers are mineral
• the finer or the fillers are mineral, the lamellar filler (s) being chosen from kaolin and talc, and mixtures thereof,
• the finer fillers are selected from kaolin, calcium carbonate, barium sulfate, silica, titanium dioxide, and mixtures thereof,
• the one or more finer fillers being chosen from among the kaolins,
• the dry weight of the lamellar filler (s) being between 3 and 58% of the total dry weight of the precoat, the quantity by weight of lamellar filler being preferably greater than that of the finer fillers,
• the percentage of lamellar charges, expressed as dry weight, relative to the total of the charges, expressed in dry weight, being between 10 and 90%, preferably between 40 and 90% and even more preferably between 60 and 90%,
• the pre-layer may comprise a binder
• the binder having a glass transition temperature T g less than or equal to 25 ° C., and more preferably at 10 ° C., measured according to ASTM standard El 356,
• the binder being chosen from latices of styrene-butadiene, styrene-acrylic, acrylic, butyl-acrylate and butyl-aryl-styrene-acrylonitrile chemical nature, and preferably styrene-butadiene-type latexes,
• the binder comprises a polymer of chemical nature not present in the covering layer
• the binder being introduced in latex form
• the quantity of binder is at least 15 parts in dry relative to the dry charges (100 parts), preferably more than 25, more preferably 30 parts,
• a covering layer can be applied without calendering of the substrate covered by the precoat
• the covering layer may be the single layer covering the precoat
• the covering layer may comprise one or more polymers chosen from copolymers based on PVdC or styrene-acrylic,
• the amount of precoat is less than or equal to 12 g / m 2 by dry weight
• the amount of covering layer is less than or equal to 10 g / m 2 by dry weight, a layer is applied in line on the paper machine on the face of the substrate opposite to that carrying the covering layer, in particular a printability layer,
• the covering layer consists of a heat-sealable polymer
• the water vapor permeability of the barrier paper is less than 150 g / m 2 / 24h, better still than 100 g / m 2 / 24h, measured according to ASTM F 1249 under tropical conditions at 38 ° C. and 90% relative humidity,
• the grammage of the fibrous substrate is between 25 and 180 g / m 2 .
• the paper is heat-sealable from 90 ° C, when the sealing is done on hot tongs, under 3 bar, and for 0.5 s,
• the substrate bears two identical pre-layers on its opposite faces or two layers of different natures
• the paper is heat-sealable, in particular on itself, at a production rate greater than or equal to 40 bags per minute, on Vertical Form, Fill and Seal (VFFS) type vertical packaging machines, along lines of longitudinal sealing of 330 mm per bag,
• VFFS Vertical Form, Fill and Seal
• the paper is heat-sealable to itself with a sealing force greater than or equal to 2 N / 15 mm, measured at a 90 degree angle according to the Tappi T540 standard at a speed of 100 mm / min, when the sealing is carried out on hot tongs, 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 covering layer is greater than or equal to 70 ° C.
• the final grammage of the paper is between 45 and 200 g / m 2 .

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Dispersion Chemistry (AREA)
• Paper (AREA)
• Wrappers (AREA)
• Laminated Bodies (AREA)

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• 2014
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