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
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/20—Macromolecular organic compounds
  • D21H17/21—Macromolecular organic compounds of natural origin; Derivatives thereof
  • D21H17/24—Polysaccharides
• • 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
  • D21H19/12—Coatings without pigments applied as a solution using water as the only solvent, e.g. in the presence of acid or alkaline compounds
• • 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
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/20—Macromolecular organic compounds
  • D21H17/33—Synthetic macromolecular compounds
  • D21H17/34—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H17/37—Polymers of unsaturated acids or derivatives thereof, e.g. polyacrylates
• • 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
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/20—Macromolecular organic compounds
  • D21H17/33—Synthetic macromolecular compounds
  • D21H17/34—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H17/37—Polymers of unsaturated acids or derivatives thereof, e.g. polyacrylates
  • D21H17/375—Poly(meth)acrylamide
• • 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
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/20—Macromolecular organic compounds
  • D21H17/33—Synthetic macromolecular compounds
  • D21H17/34—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H17/41—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing ionic groups
  • D21H17/42—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing ionic groups anionic
• • 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
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/63—Inorganic compounds
  • D21H17/66—Salts, e.g. alums
• • 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
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/71—Mixtures of material ; Pulp or paper comprising several different materials not incorporated by special processes
• • 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
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/71—Mixtures of material ; Pulp or paper comprising several different materials not incorporated by special processes
  • D21H17/72—Mixtures of material ; Pulp or paper comprising several different materials not incorporated by special processes of organic material
• • 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
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/71—Mixtures of material ; Pulp or paper comprising several different materials not incorporated by special processes
  • D21H17/74—Mixtures of material ; Pulp or paper comprising several different materials not incorporated by special processes of organic and inorganic material
• • 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
  • D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
  • D21H21/14—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties characterised by function or properties in or on the paper
  • D21H21/18—Reinforcing agents
• • 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
  • D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
  • D21H21/14—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties characterised by function or properties in or on the paper
  • D21H21/18—Reinforcing agents
  • D21H21/20—Wet strength agents
• • 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
  • D21H23/32—Addition to the formed paper by contacting paper with an excess of material, e.g. from a reservoir or in a manner necessitating removal of applied excess material from the paper
  • D21H23/34—Knife or blade type coaters
• • 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
  • D21H23/46—Pouring or allowing the fluid to flow in a continuous stream on to the surface, the entire stream being carried away by the paper
  • D21H23/48—Curtain coaters
• • 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
  • D21H23/52—Addition to the formed paper by contacting paper with a device carrying the material
  • D21H23/56—Rolls
• • 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
  • D21H5/00—Special paper or cardboard not otherwise provided for
  • D21H5/0005—Processes or apparatus specially adapted for applying liquids or other fluent materials to finished paper or board, e.g. impregnating, coating
  • D21H5/0047—Processes or apparatus specially adapted for applying liquids or other fluent materials to finished paper or board, e.g. impregnating, coating by spraying or projecting

Definitions

• the invention relates to a method for treating the surface of paper to improve its mechanical strength.
• starches such as corn starch, wheat starch, potato starch, or chemically modified starches were used as layer binding agents. The practice was to drop / spray the starch slurry on the wet paper, then promote the gelatinization of the starch during the drying process to improve the adhesive strength.
• a decrease in the mechanical performance of the paper is, however, observed when the drying profile is too violent because this causes rapid removal of water from the starch slurry deposited on the surface of the paper.
• starch grains need high temperature, water and time to "burst / explode” and therefore for the starch to gelatinize. It is the gelatinized starch that provides the mechanical properties. If the water from the slurry deposited on the surface is removed too quickly by a too violent drying profile, or by an absorption of water in the paper too fast, the grains dry as they are, without gelatinizing, therefore without adding any performance.
• PAM polyacrylamide
• the Applicant has surprisingly discovered that by applying to the surface of the paper and / or of at least one of its layers a mixture of a polysaccharide and of an aqueous dispersion comprising (a) particles of at least one polymer anionic water-swellable and (b) at least one compound selected from an inorganic salt, an organic salt, an organic dispersing polymer and mixtures thereof, the mechanical delamination properties are higher.
• aqueous dispersion comprising (a) particles of at least one polymer anionic water-swellable and (b) at least one compound selected from an inorganic salt, an organic salt, an organic dispersing polymer and mixtures thereof.
• the invention therefore relates to a process for treating the surface of the paper, and / or at least one of its layers, comprising the following successive steps:
• aqueous dispersion D comprising (a) particles of at least one anionic water-swellable polymer P and (b) at least one compound selected from an inorganic salt, an organic salt, an organic dispersing polymer and mixtures thereof, iii) Mix the suspension S and the dispersion D to obtain a mixture M,
• wet paper is understood to mean the paper resulting from the manufacturing process before passing through the dryer.
• the aqueous suspension S contains between 0.5 and 30% by mass of polysaccharide in water, and even more advantageously between 5 and 20% by mass.
• the polysaccharide is chosen from native starch, amylose, amylopectin, cellulose and compounds derived from cellulose, modified starches such as starches treated by an enzymatic route, hydrolyzed starches, heated starches, cationic starches, such as those resulting from the reaction of a starch with a tertiary amine to form a quaternary ammonium salt, anionic starches, amphoteric starches; and any combination of these.
• modified starches such as starches treated by an enzymatic route, hydrolyzed starches, heated starches, cationic starches, such as those resulting from the reaction of a starch with a tertiary amine to form a quaternary ammonium salt, anionic starches, amphoteric starches; and any combination of these.
• the polysaccharide is native starch.
• Native starch is the product of the extraction of starch without subsequent modification.
• the water-swellable polymer P, used in step ii) of the process of the invention is also known as a super-absorbent polymer. Generally, it has a water absorption capacity greater than 10 times its volume. In a particularly advantageous manner for the process according to the invention, within the dispersion, the water-swellable polymer is not or only slightly hydrogenated. Low in water content means that it retains a water absorption capacity greater than 10 times its volume.
• the water-swellable polymer P used in step ii) of the process of the invention is anionic, which means that its resulting charge is negative.
• This polymer can be prepared from different water-soluble monomers, in particular from at least one water-soluble monomer comprising at least one ethylenic double bond. It can thus be prepared from at least one anionic monomer, from at least one nonionic monomer, from at least one cationic monomer or even from at least one zwitterionic monomer, alone or in combination. mixed.
• the water-swellable polymers P used in the process of the invention are obtained by crosslinking and therefore form three-dimensional networks.
• anionic monomers at least one monomer chosen from among:
• sulfonic acid function for example 2-acrylamido-2-methylpropane sulfonic acid (AMPS), allyl sulfonic acid and, methallyl sulfonic acid and their salts.
• APMS 2-acrylamido-2-methylpropane sulfonic acid
• allyl sulfonic acid and, methallyl sulfonic acid and their salts for example 2-acrylamido-2-methylpropane sulfonic acid (AMPS), allyl sulfonic acid and, methallyl sulfonic acid and their salts.
• APMS 2-acrylamido-2-methylpropane sulfonic acid
• nonionic monomers at least one monomer chosen from among:
• N-alkylacrylamides for example Nisopropylacrylamide, N-tert-butylacrylamide; N, N-dialkylacrylamides, for example N, N-dimethylacrylamide and N-methylolacrylamide; methacrylamide and its derivatives, in particular N-alkylmethacrylamides, for example N-isopropylmethacrylamide, N-tert-butylmethacrylamide; N, Ndialkylmethacrylamides, for example NN-dimethylmethacrylamide and N-methylolmethacrylamide;
• vinylformamide N-vinylpyridine, N-vinylpyrrolidone, hydroxyalkylacrylates, hydroxyalkyl methacrylates, acrylates carrying alkoxy chains; methacrylates carrying alkoxy chains.
• cationic monomers at least one monomer chosen from among:
• diallyldialkyl ammonium salts for example diallyl dimethyl ammonium chloride (DADMAC);
• DADMAC diallyl dimethyl ammonium chloride
• ADAME dialkylaminoethyl
• MADAME dialkylaminoethyl methacrylate
• zwitterionic monomers at least one monomer chosen from among:
• sulfobetaine monomers such as sulfopropyl dimethylammonium ethyl methacrylate, sulfopropyl dimethylammonium propylmethacrylamide, sulfopropyl 2-vinylpyridinium;
• phosphobetaine monomers such as phosphatoethyl trimethylammonium ethyl methacrylate, carboxybetaine monomers.
• the water-swellable polymer P can be a copolymer prepared from the monomers described above or from the monomers described above and at least one other monomer chosen from monomers hydrophobic, for example styrene, alkyl-acrylates, alkyl-methacrylates, aryl-acrylates, aryl-methacrylates, hydrophobic acrylamide derivatives; amphiphilic monomers, for example dodecyl poly (oxyethylene) methacrylate, behenyl poly (oxyethylene) methacrylate; or from natural polymers such as, for example, cellulose derivatives, polysaccharides, clays, for example these natural polymers, can be grafted onto the water-swellable polymers of the invention to form another family of water-swellable polymers according to the invention.
• monomers hydrophobic for example styrene, alkyl-acrylates, alkyl-methacrylates, aryl-acrylates, aryl-methacrylates, hydrophobic acrylamide
• the water-swellable polymer P is a copolymer of at least one nonionic monomer and of at least one anionic monomer.
• the anionic water-swellable polymer P is derived from at least 1 mol% of at least one water-soluble anionic monomer comprising an ethylenic double bond and at least one carboxylic or sulfonic acid function and at least 5 mol% of at least a nonionic monomer chosen from acrylamide, methacrylamide and their derivatives, vinylformamide and N-vinylpyrrolidone.
• the water-swellable polymer P contains between 1 and 40 mol% of at least one water-soluble anionic monomer comprising an ethylenic double bond and at least one carboxylic or sulphonic acid function and between 60 and 99 mol% of at least one nonionic monomer.
• the water-swellable polymer P contains between 1 and 40 mol% of at least one water-soluble anionic monomer comprising an ethylenic double bond and at least one carboxylic or sulphonic acid function and between 60 and 99 mol% of at least one nonionic monomer.
• acrylamide, methacrylamide and their derivatives, vinylformamide and N-vinylpyrrolidone chosen from acrylamide, methacrylamide and their derivatives, vinylformamide and N-vinylpyrrolidone.
• the water-soluble anionic monomer is chosen from acrylic acid, methacrylic acid and their salts, 2-acrylamido-2-methylpropanesulfonic acid and its salts, itaconic acid and its salts, allyl sulfonic acid and its salts, methallyl sulfonic acid and its salts.
• the water-swellable anionic polymer P is a copolymer of acrylamide and sodium acrylate.
• the aqueous dispersion D comprises from 5 to 60% by dry weight, and even more preferably from 15 to 35% by dry weight, of water-swellable polymer P.
• the particles of water-swellable polymer P advantageously have a diameter allowing their dispersion.
• the particles have an average diameter ranging from 0.1 and 1000 ⁇ m, more preferably ranging from 0.1 and 200 ⁇ m, even more preferably ranging from 0.1 and 20 ⁇ m.
• the average diameter of the particles can be determined by any method known to those skilled in the art, for example by binocular microscopy.
• the aqueous dispersion D comprises a compound (b) which has a function of balancing agent. It is a water soluble or water miscible compound.
• the dispersion according to the invention makes it possible to totally or partially inhibit the hydrogen-swelling capacity of the polymer P.
• the water-swellable polymer (P ) is present in the form of particles and is little or little in the hydrogenated state.
• the aqueous dispersion comprises at least one compound (b) chosen from:
• - mineral or organic salts comprising at least one anion chosen from sulphates, dihydrogenphosphates, phosphates and halides;
• - mineral or organic salts comprising at least one cation chosen from sodium, potassium, ammonium, magnesium, calcium and aluminum;
• organic polymers chosen from polymers or copolymers based on acrylic acid, 2-acrylamido-2-methylpropanesulfonic acid and their salts and acrylamide with a molecular weight ranging from 1000 to 30,000 g. mol 1 .
• dispersion D comprises, as compound (b), from 8 to 27% by mass of inorganic salt or of organic salt and from 5 to 20% by dry mass of dispersing organic polymer.
• dispersion D can also comprise at least one additive chosen from polyfunctional alcohols, for example glycerol, polyalkylene glycols such as polyethylene glycol and polypropylene glycol.
• the additive is present in an amount by mass of dispersion ranging from 0.001 to 20% by weight, preferably from 0.5 to 10%
• the mixture M of the suspension S and of the dispersion D is advantageously carried out with stirring by adding the dispersion D in the suspension S, so that the concentration of the polymer P in M is between 0.001 to 10% by mass dried.
• the application of the mixture M (S + D) to the surface of the paper and / or of at least one of its layers, also called coating of the paper can be carried out by any means of coating.
• this coating means is a coater or a spray bar.
• step iv) of the process of the invention which consists in applying the mixture M, is carried out at a temperature between 10 and 100 ° C and even more preferably between 30 ° C and 100 ° C.
• the M mixture advantageously improves the mechanical strength of the paper.
• the present invention relates to a method of improving the mechanical strength of the paper comprising applying to the surface of the paper and / or at least one of its layers of the mixture M according to the invention.
• the present invention also relates to the use of a water-swellable polymer P according to the invention for the treatment of paper, in particular the use of a water-swellable polymer P in combination with a polysaccharide, for the treatment of paper, in particular to improve the mechanical strength of the paper.
• the present invention also relates to the use of the mixture M for the treatment of paper, in particular to improve the mechanical strength of the paper.
• Leaf formation with application in the form of a spray on a wet leaf :
• the paper formers are produced with an automatic dynamic former.
• the pulp is prepared by disintegrating, for 25 minutes, 90 grams of recycled cardboard fibers in 2 liters of hot water (pH neutral pulp composed of 100% recycled fibers).
• the paste thus obtained is then diluted in water to a volume of 6 liters. Once the consistency is precisely measured, the necessary quantity of this paste is taken so as to finally obtain a sheet with a basis weight of 90 g / m 2 .
• the paste is then introduced into the vat of the dynamic formette, diluted to a consistency of 0.5% and stirred moderately with a mechanical stirrer in order to homogenize the aqueous suspension.
• a blotter and the training cloth are placed in the bowl of the dynamic former before starting to rotate the bowl at 1000 rpm and construct the wall of water.
• the sheet is then produced by 23 round trips of the nozzle projecting the dough into the wall of water.
• the forming fabric, along with the formed fiber network is removed from the bowl of the dynamic formatter and placed on a table.
• a dry blotter is placed on the side of the wet fiber mat and is pressed once with a roller. The whole is turned over and the canvas is gently separated from the fibrous mat.
• a second dry blotter is placed before turning the assembly over and removing the first waterlogged blotter.
• An aqueous suspension of uncooked native starch, with or without the polymer according to the invention, is then applied in the form of a spray (gun, bar, nebulizer, etc.), so as to uniformly deposit a dry quantity of the order of of 1 g / m 2 .
• the wet sheet is then folded in two on the treated face, pressed between two rollers under 4 bars of pressure, then after having renewed the blotter, dried on a dryer stretched for 10 minutes at 117 ° C.
• the blotter is then removed and the sheet thus formed is conditioned for a minimum of 12 hours in a room with controlled humidity and temperature (50% relative humidity and 23 ° C temperature).
• Industrial cardboard is used on which is deposited, using a threaded bar, an aqueous suspension S of uncooked native starch with or without addition of polymer dispersion D (the suspension S with additives corresponds to the mixture M).
• This sheet is then folded in half on the treated face, placed in a blotter, pressed between two rollers under 4 bars of pressure, then dried on a dryer stretched for 10 minutes at 1 17 ° C.
• the blotter is then removed and the sheet thus formed is conditioned for a minimum of 12 hours in a room with controlled humidity and temperature (50% relative humidity and 23 ° C temperature).
• the equipment used for the dry sheet coating is a Multicoater K 303 type laboratory coater from RK Print Coat Instruments. Dry strength tests:
• the burst is measured with a Messmer Buchel M 405 burst atometer (average over 12 values), according to the TAPPI T403 om-02 standard. The result is expressed in kPa.
• the Burst Index expressed in kPa.m 2 / g, is determined by dividing this value by the basis weight of the sheet.
• compositions E and C are diluted to 5 g / L in deionized water.
• a turbid suspension is obtained which is allowed to settle in a tube until an opalescent deposit is obtained at the bottom of the tube and a clear supernatant.
• the opalescent deposit represents the accumulation of particles of water-swellable polymer P1.
• An industrial boxboard of 110 g / m 2 is used , the mechanical performance of which corresponds to the “white” test when it is not treated.
• a native wheat starch milk with 18% dry matter is deposited on it, using the laboratory coater (threaded bar No. 3).
• Adding native starch with synthetic polymers provides an undeniable gain in terms of mechanical strength performance of the paper, here resistance to delamination (internal cohesion), as well as resistance to bursting.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Inorganic Chemistry (AREA)
• Paper (AREA)

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• 2019
  • 2019-03-14 FR FR1902634A patent/FR3093738B1/fr active Active
• 2020
  • 2020-03-13 CN CN202080020624.3A patent/CN113557331A/zh active Pending
  • 2020-03-13 WO PCT/EP2020/056774 patent/WO2020182977A1/fr active Application Filing
  • 2020-03-13 FI FIEP20709236.2T patent/FI3938575T3/fi active
  • 2020-03-13 CA CA3132084A patent/CA3132084A1/fr active Pending
  • 2020-03-13 KR KR1020217029481A patent/KR20210138605A/ko active Search and Examination
  • 2020-03-13 US US17/437,496 patent/US11781271B2/en active Active
  • 2020-03-13 BR BR112021018153A patent/BR112021018153A2/pt unknown
  • 2020-03-13 EP EP20709236.2A patent/EP3938575B8/de active Active

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