EP4058632A1 - Cmf réticulée - Google Patents

Cmf réticulée

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Publication number
EP4058632A1
EP4058632A1 EP20803189.8A EP20803189A EP4058632A1 EP 4058632 A1 EP4058632 A1 EP 4058632A1 EP 20803189 A EP20803189 A EP 20803189A EP 4058632 A1 EP4058632 A1 EP 4058632A1
Authority
EP
European Patent Office
Prior art keywords
film
mfc
metal ion
crosslinking agent
drying
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP20803189.8A
Other languages
German (de)
English (en)
Inventor
Ali Naderi
Johan Larsson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Billerud AB
Original Assignee
Billerudkorsnas AB
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Billerudkorsnas AB filed Critical Billerudkorsnas AB
Publication of EP4058632A1 publication Critical patent/EP4058632A1/fr
Pending legal-status Critical Current

Links

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
    • D21H11/00—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only
    • D21H11/16—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only modified by a particular after-treatment
    • D21H11/18—Highly hydrated, swollen or fibrillatable fibres
    • 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
    • D21H11/00—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only
    • D21H11/16—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only modified by a particular after-treatment
    • D21H11/20—Chemically or biochemically modified fibres
    • 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
    • D21H17/03—Non-macromolecular organic compounds
    • D21H17/05—Non-macromolecular organic compounds containing elements other than carbon and hydrogen only
    • D21H17/06—Alcohols; Phenols; Ethers; Aldehydes; Ketones; Acetals; Ketals
    • 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
    • D21H17/03—Non-macromolecular organic compounds
    • D21H17/05—Non-macromolecular organic compounds containing elements other than carbon and hydrogen only
    • D21H17/14—Carboxylic acids; 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
    • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
    • D21H17/63—Inorganic 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
    • D21H17/63—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
    • 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
    • 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
    • D21H19/64—Inorganic 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
    • 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
    • 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
    • D21H23/26—Addition to the formed paper during paper manufacture by selecting point of addition or moisture content of the paper

Definitions

  • the present disclosure relates to the production of films comprising microfibrillated cellulose (MFC).
  • MFC microfibrillated cellulose
  • MFC microfibrillated cellulose
  • TEMPO-oxidized cellulose nanofibres are used to form a film that is crosslinked with ions to withstand oxygen at increased relative humidity (RH).
  • RH relative humidity
  • the crosslinking is performed by immersion in a solution of ions for hours and the film is thereafter washed for hours and dried for days.
  • JP2016089307 discloses a method of coating a paper made of cellulose with an acid-type cellulose nanofiber dispersion that is crosslinked with a polyvalent metal compound.
  • the crosslinking is taught to be conducted by immersion and washing for more than 35 minutes.
  • the paper is thereafter laminated with a heat-seal layer and evaluated as suitable for paper container that can be used under hot water treatment.
  • EP2371892 discloses a lab method of spraying cross-linking solution over a nanocellulose film to crosslink it, wherein the film is very thin (below 1 pm) and the concentration of crosslinker is relatively high.
  • An objective of the present disclosure is to provide a method of producing an MFC-based film having improved oxygen-barrier properties, which method allows for high productivity in full-scale production of the film on a paper machine.
  • a method for producing a crosslinked film comprising microfibrillated cellulose comprising the steps of: a) applying an aqueous composition comprising a crosslinking agent to a film comprising MFC, which film has a moisture content of less than 15 %, such as less than 10 %, such as less than 8 %, provided that if the crosslinking agent is a metal ion, the metal ion is a divalent metal ion having a concentration in the aqueous composition of below 100 mM, such as below 50 mM; and b) drying the film from step a) such that at least 50% of the water absorbed by the film following the application of step a) is removed within five minutes of the performance of step a) or within five minutes from the start of step a).
  • the MFC preferably comprises a chargeable moiety and has a charge density measured according to SCAN-CM 65:02 of 500-1800 peq/g.
  • the drying in step b) is preferably conducted by means of heated cylinders, such as steam-heated cylinders, and/or contactless drying, such as by hot air and/or infrared radiation.
  • the reason for applying the crosslinking agent to a “dry” MFC film is that such a film comprises regions of dense/crystallized MFC structures separated by regions of less dense/amorphous MFC, which is more accessible for the crosslinking agent.
  • the crosslinking agent crosslinks the regions of less dense/amorphous MFC and thereby reduces their mobility. Further, the inventors believe that the relatively short combined time period of step a) and b) may focus the crosslinking action to the regions where it is most needed.
  • a crosslinked film comprising MFC obtained by the method exhibiting an oxygen permeability (OP) of less than 500 ml pm nr 2 d 1 bar 1 at 80% RH according to the standards ASTM D3985 and F1927.
  • the crosslinker may be a divalent metal ion, such as an ion selected from the group consisting of Zn 2+ , Ca 2+ , Cu 2+ and Mg 2+ , and the MFC used to produce the film may have a charge density measured according to SCAN-CM 65:02 of 500-1800 peq/g.
  • the present disclosure provides a method for producing a crosslinked film comprising microfibrillated cellulose (MFC), wherein the method comprises the steps of: a) applying an aqueous composition comprising a crosslinking agent to a film formed from an aqueous suspension comprising MFC, which film has a moisture content of less than 15 %, such as less than 10 %, such as less than 8 %, provided that if the crosslinking agent is a metal ion, the metal ion is a divalent metal ion having a concentration in the aqueous composition of below 50 mM and the MFC has a charge density measured according to SCAN-CM 65:02 of 500-1800 peq/g; and
  • step b) drying the film from step a) such that at least 50% of the water absorbed by the film following the application of step a) is removed within five minutes from the start of step a).
  • step b) is instead drying the film from step a) such that the moisture content of the film is less than 30%, such as less than 25% within five minutes from the start of step a), such as within three minutes from the start of step a).
  • the divalent metal ion concentration in the aqueous composition is below 50 mM, typically above 0.1 mM, such as being above 0.1 mM and below 50 mM, such as 0.5-45 mM.
  • a relatively low concentration is advantageous since a too high concentration may cause the fibrils to crosslink too tight to each other yielding an impaired barrier.
  • the divalent cation is preferably selected from the group consisting of Zn 2+ , Ca 2+ , Cu 2+ and Mg 2+ . Zn 2+ and Ca 2+ are particularly preferred. Ca 2+ may be considered to be the most preferred divalent cation since it is relatively small and better penetrates the amorphous regions than larger ions.
  • the MFC has a charge density measured according to SCAN-CM 65:02 of 500-1800 peq/g, such as 500-1000 peq/g.
  • Charge density is measured on fibres that are chemically modified, and as it is the total charge density being measured, the charge density of a fibre prior to fibrillation is the same as the charge density of the fibrils produced by fibrillating said fibre.
  • the charge density of the MFC of step a) emanates from a chargeable moiety present on the MFC.
  • the chargeable moiety is selected from carboxy, carboxymethyl, carboxyalkyl, sulfonyl, sulfoethyl and phosphoryl groups.
  • the chemical modification introducing the chargeable moiety is preferably selected from the group consisting of TEMPO oxidation, alkoxylation, phosphorylation, sulfonation, sulfoethylation and chlorite oxidation preceded by introduction of aldehydes, for example through periodate oxidation.
  • the alkoxylation is preferably carboxymethylation.
  • the MFC of step a) comprises quaternary amines.
  • the crosslinking agent may in such case be a multivalent anion, such as a phosphate ion or a polycarboxylate ion.
  • the introduction of quaternary amines is preferably conducted via a compound that both contains a group reacting with hydroxyl groups to form covalent bonds as well as a quaternary ammonium group.
  • the introduction may also be conducted via a compound that both contains a group reacting with hydroxyl groups to form covalent bonds and a group that can further react to attach an amine.
  • the group reacting with hydroxyl groups is selected from any of epoxy, halohydrin capable of forming epoxy, active halogen, isocyanate, active vinyl or methylol.
  • examples of compounds bearing a group reacting with hydroxyl groups to form covalent bonds as well as a quaternary ammonium group are 2,3-epoxypropyl trimethylammonium chloride (EPTMAC), chlorocholine chloride (CIChCl), glycidyl trimethylammonium chloride and 3-chloro-2-hydroxypropyl trimethyl ammonium chloride. It may be advantageous to crosslink cationic amine-functional MFC since such functionalization chemistry is readily available on an industrial scale.
  • the film may further comprise nanofiller, e.g. in an amount of 1-20 wt.%.
  • Nanofillers are particles characterized by high surface areas and high aspect ratios. The high surface areas and aspect ratios may be beneficial in barrier applications, since the particles can make the diffusion of the gas molecules through the coating layer more difficult, thus improving the barrier properties.
  • Said nanofiller is preferably chosen from bentonite, kaolin or montmorillonite.
  • the crosslinker is not glutaraldehyde when the film comprises nanofiller. Instead, it maybe Zn 2+ in a concentration of 0.1-5 mM or Ca 2+ in a concentration of 0.1-50 mM.
  • the crosslinking agent may form covalent bonds.
  • the crosslinking agent is preferably selected from the group consisting of borax, glutaraldehyde, citric acid or polycarboxylic acid.
  • Glutaraldehyde may be used together with a catalyst, such as zinc nitrate, and the MFC typically has a low charge, such as a charge density measured according to SCAN-CM 65:02 of 10-200 peq/g, such as 10-100 peq/g.
  • the method is suitably carried out in a full-scale paper machine, i.e. a paper machine running at a speed of at least 300 m/min and having a trim width of at least 1500 mm, such as at least 3000 mm. Consequently, only a very limited period of time is available for the completion of each step of the process.
  • Steps a) and b) are preferably carried out in or after a drying section of the paper machine.
  • a drying section of the paper machine there is typically arranged a press section.
  • a forming section such as a wire section.
  • Step a) may be carried out by means of a size press or a film press.
  • step a) comprises the spraying the aqueous composition onto the film.
  • aqueous composition is added by means of a size press or film press, is typically has a viscosity of 10-1000 mPas, preferably 10-300 mPas, when measured as dynamic viscosity with a Brookfield rotational viscometer using spindle no.4 at 100 rpm and 25 °C according to the Brookfield instruction sheet.
  • a curtain coater or a direct rod coater is used for the application of the aqueous composition.
  • the viscosity of the aqueous composition is typically 100-800 mPas when measured as dynamic viscosity with a Brookfield rotational viscometer using spindle no.4 at 100 rpm and 25 °C according to the Brookfield instruction sheet.
  • a blade coater is used for the application of the aqueous composition.
  • the viscosity of the aqueous composition is typically 400-1500 mPas when measured as dynamic viscosity with a Brookfield rotational viscometer using spindle no.4 at 100 rpm and 25 °C according to the Brookfield instruction sheet.
  • the aqueous composition may comprise a polymer, such as starch, carboxymethyl cellulose (CMC), polyvinyl alcohol (PVOH) or MFC.
  • a polymer such as starch, carboxymethyl cellulose (CMC), polyvinyl alcohol (PVOH) or MFC.
  • the composition may comprise a rheology modifier.
  • the drying in step b) is preferably conducted by means of heated cylinders, such as steam-heated cylinders, and/or contactless drying, preferably using hot air and/or infrared radiation.
  • the method may further comprise the steps of: i) providing the aqueous suspension comprising MFC; and ii) forming a web from the aqueous suspension and dewatering and drying the web to form the film to which the aqueous composition comprising a crosslinking agent is applied in step a).
  • steps i) and ii) are carried out in a paper machine, such as the same paper machine as the one used for steps a) and b). Thereby, the overall efficiency of the method may be improved.
  • steps a) and b) are carried out offline, which means that they are not carried out in the paper machine used for steps i) and ii). Steps a) and b) may even be carried out at a different location than steps i) and ii).
  • Step ii) is preferably carried out in the forming section of a paper machine.
  • the width of the wire of the forming section maybe at least 1500 mm, such as at least 3000 mm.
  • the method further comprises a step of fibrillating cellulosic fibres to provide the MFC of step i).
  • This step may comprise mechanical, enzymatic and/ or chemical sub-steps known to the skilled person.
  • a chemical sub-step may introduce a chargeable moiety that facilitates the crosslinking.
  • MFC means nano-scale cellulose particle fibres or fibrils with at least one dimension less than 100 nm.
  • MFC comprises partly or totally fibrillated cellulose or lignocellulose fibres.
  • the liberated fibrils have a diameter less than 100 nm, whereas the actual fibril diameter or particle size distribution and/or aspect ratio (length/width) depends on the source and the manufacturing methods.
  • the smallest fibril is called elementary fibril and has a diameter of approximately 2-4 nm, while it is common that the aggregated form of the elementary fibrils, also defined as microfibril is the main product that is obtained when making MFC e.g. by using an extended refining process or a pressure-drop disintegration process.
  • the length of the fibrils can vary from around 1 to more than 10 micrometers.
  • a coarse MFC grade might contain a substantial fraction of fibrillated fibres, i.e. protruding fibrils from the tracheid (cellulose fibre), and with a certain amount of fibrils liberated from the tracheid.
  • MFC cellulose microfibrils
  • fibrillated cellulose such as fibrillated cellulose, nanofibrillated cellulose (NFC), fibril aggregates, nanoscale cellulose fibrils, cellulose nanofibres, cellulose nanofibrils (CNF), cellulose microfibres (CMF), cellulose fibrils, microfibrillar cellulose, microfibril aggregrates and cellulose microfibril aggregates.
  • CNF cellulose nanofibrils
  • CMF cellulose microfibres
  • MFC can also be characterized by various physical or physical- chemical properties such as large surface area or its ability to form a gel-like material at low solids content (1-5 wt.%) when dispersed in water.
  • the cellulose fibre is preferably fibrillated to such an extent that the final specific surface area of the formed MFC is from about 1 to about 200 m 2 /g, or more preferably 50-200 m 2 /g when determined for a freeze-dried material with the BET method (Brunauer, Stephen, Paul Hugh Emmett, and Edward Teller. "Adsorption of gases in multimolecular layers.” Journal of the American chemical society 60.2 (1938): 309-319.). Nitrogen (N2) gas adsorption isotherms are recorded using an ASAP 2020 (Micromeritics, USA) instrument. Measurements are performed at liquid nitrogen temperatures (i.e., 77 K), and the specific surface areas of the samples were obtained from the isotherms using the BET method.
  • Nitrogen (N2) gas adsorption isotherms are recorded using an ASAP 2020 (Micromeritics, USA) instrument. Measurements are performed at liquid nitrogen temperatures (i.e., 77 K), and the specific surface areas of the samples were obtained from the is
  • MFC multi-pass refining
  • pre-hydrolysis followed by refining or high shear disintegration or liberation of fibrils.
  • One or several pre-treatment step(s) is/are usually required in order to make MFC manufacturing both energy efficient and sustainable.
  • the cellulose fibres of the pulp to be supplied may thus be pre-treated enzymatically or chemically, for example to hydrolyse or swell fibre or reduce the quantity of hemicellulose or lignin.
  • the cellulose fibres may be chemically modified before fibrillation. After such chemical modification, it is typically easier to disintegrate the fibres into MFC or nanofibrillar size or NFC.
  • the nanofibrillar cellulose may contain some hemicelluloses; the amount is dependent on factors such as plant source and pulping process.
  • Mechanical disintegration of the pre-treated fibres, e.g. hydrolysed, pre-swelled, or oxidized cellulose rawmaterial is carried out with suitable equipment such as a refiner, grinder, homogenizer, collider, friction grinder, ultrasound sonicator, fluidizer such as microfluidizer, macrofluidizer or fluidizer-type homogenizer.
  • suitable equipment such as a refiner, grinder, homogenizer, collider, friction grinder, ultrasound sonicator, fluidizer such as microfluidizer, macrofluidizer or fluidizer-type homogenizer.
  • the product might also contain fines or e.g. other chemicals present in wood fibres or in papermaking process.
  • the product might also contain various amounts of micron size fibre particles that have not been efficiently fibrillated.
  • MFC is produced from wood cellulose fibres, both from hardwood or softwood fibres. It can also be made from, agricultural fibres such as wheat straw pulp, bamboo, bagasse, or other non-wood fibre sources. It is preferably made from pulp of virgin fibre, e.g. mechanical, chemical and/or thermomechanical pulps, preferably never-dried fibres.
  • the above described definition of MFC includes, but is not limited to, the proposed TAPPI standard W13021 on cellulose nanofibril (CNF) defining a cellulose nanofibre material containing multiple elementary fibrils with both crystalline and amorphous regions, having a high aspect ratio with width of 5-3 onm and aspect ratio usually greater than 50.
  • CNF cellulose nanofibril
  • the amount of MFC in the film is preferably at least 50% by dry weight, such as at least 70% by dry weight, such as at least 80% by dry weight.
  • the film typically has a grammage measured according to ISO 536:2012 of 5- 100 g/m 2 , such as 5-70 g/m 2 , such as 10-70 g/m 2 , such as 10-60 g/m 2 , such as 20-60 g/m 2 , such as 30-60 g/m 2 , preferably 45-60 g/m 2 , more preferably 50-60 g/m 2 .
  • the crosslinked film typically has a density of o.7-1.4 g/cms, such as o.8-1.2 g/cms measured according to ISO 534:2011.
  • the crosslinked film typically has a thickness of 1-100 pm, such as 5-70 pm, such as 10-50 pm measured according to ISO 534:2011. By having a thickness of several micrometres, the crosslinking action of the film can be focused to the regions where it is most needed, which is beneficial for the barrier properties.
  • step a) At least 75% of the water absorbed by the film following the application of step a) is removed within five minutes from the start of step a).
  • step a) 50% of the water absorbed by the film following the application of step a) is removed within three minutes from the start of step a), such as within two minutes from the start of step a). Thereby, the efficiency of the method is increased.
  • step b) maybe carried out such that the moisture content of the film is less than 30%, such as less than 25% within five minutes of the performance of step a), such as within three minutes of the performance of step a).
  • the crosslinked film produced by the method of the present disclosure is an oxygen barrier, exhibiting an oxygen permeability (OP) of less than 500 ml pm nr 2 d 1 bar 1 at 80% RH according to the standards ASTM D3985 and F1927.
  • OP oxygen permeability
  • the crosslinked film is typically crosslinked with a divalent metal ion and the MFC used to produce the film typically has a charge density measured according to SCAN-CM 65:02 of 500-1800 peq/g.
  • the divalent metal ion is typically selected from the group consisting of Zn 2+ , Ca 2+ , Cu 2+ and Mg 2+ .
  • the method for producing a crosslinked film comprising MFC comprises the steps of:
  • an aqueous composition comprising a crosslinking agent to the film comprising MFC, which film has a moisture content of less than 15 %, such as less than 10 %, provided that if the crosslinking agent is a metal ion, the metal ion is a divalent metal ion having a concentration in the aqueous composition of below 50 mM, and the MFC has a charge density measured according to SCAN-CM 65:02 of 500-1800 peq/g;
  • a suspension of low-charged MFC (0.1 wt%; total charge 40 pmol/g) was filtrated and thereafter dried (50 °C; 4 h) into a film.
  • the film was dipped for 5 seconds in a solution containing either borax or glutaraldehyde acting as crosslinker.
  • the latter chemical was employed in combination with zinc nitrate, which acts as catalyst for the reaction of glutaraldehyde with hydroxyl group.
  • the film was thereafter dried (50 °C; 4 h). Films of grammages of 30 g/m 2 and 60 g/m 2 were produced. No washing was performed between the dipping and the drying.
  • a suspension of carboxymethylated MFC (0.1 wt%; total charge 800 pmol/g) was filtrated and thereafter dried (50 °C; 4 h) into a film.
  • the film was dipped for 5 seconds in a solution containing either zinc nitrate hexahydrate, calcium chloride dihydrate, iron chloride hexahydrate or aluminum chloride hexahydrate acting as crosslinkers. Subsequently the film was dried (50 °C; 4 h). Films of grammages of 20 g/m 2 , 30 g/m 2 and 60 g/m 2 were produced. No washing was performed between the dipping and the drying.
  • the transmission rate (OTR) was measured on 5 cm 2 samples using a MOCON OX-TRAN 2/21 according to the ASTM D3985 and ASTM F1927 standards.
  • the OTR measurements were performed at 23 0 C and 50% RH or 80% RH, using the same relative humidity on both sides of the sample.
  • OTR oxygen permeability
  • the weight ratio of glutaraldehyde to zinc nitrate was 1:0.76 and the concentration of glutaraldehyde in the solution was iwt.%.
  • Table 1 shows reduction of oxygen permeability at 50% and 80% RH when divalent metal ions are applied at a concentration below 100 mM.
  • the trivalent metal ions and divalent metal ions in a higher concentration failed to reduce oxygen permeability.
  • the best oxygen permeability values were obtained when Ca 2+ (1 or 10 mM) or Zn 2+ (1 mM) was added to a film comprising nanofiller.
  • Table 1 also shows reduction of oxygen permeability at 80% RH when crosslinkers forming covalent bonds are applied.

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  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Biochemistry (AREA)
  • Manufacture Of Macromolecular Shaped Articles (AREA)
  • Laminated Bodies (AREA)
  • Paper (AREA)

Abstract

L'invention concerne un procédé de production d'un film réticulé comprenant de la cellulose microfibrillée (CMF), le procédé comportant les étapes suivantes : a) l'application d'une composition aqueuse contenant un agent de réticulation à un film formé à partir d'une suspension aqueuse contenant de la CMF, ledit film ayant une teneur en humidité inférieure à 15 %, par exemple inférieure à 10 %, à condition que, si l'agent de réticulation est un ion métallique, l'ion métallique soit un ion métallique divalent ayant une concentration dans la composition aqueuse inférieure à 50 mM et que la CMF ait une densité de charge mesurée selon SCAN-CM 65:02 de 500-1800 µeq/g ; et b) le séchage du film de l'étape a) de telle sorte qu'au moins 50% de l'eau absorbée par le film après l'application de l'étape a) soit éliminée dans les cinq minutes suivant le début de l'étape a).
EP20803189.8A 2019-11-12 2020-11-12 Cmf réticulée Pending EP4058632A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP19208620.5A EP3822409A1 (fr) 2019-11-12 2019-11-12 Mfc réticulé
PCT/EP2020/081884 WO2021094440A1 (fr) 2019-11-12 2020-11-12 Cmf réticulée

Publications (1)

Publication Number Publication Date
EP4058632A1 true EP4058632A1 (fr) 2022-09-21

Family

ID=68655249

Family Applications (2)

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EP19208620.5A Pending EP3822409A1 (fr) 2019-11-12 2019-11-12 Mfc réticulé
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JP2023501001A (ja) 2023-01-17
CN114641597A (zh) 2022-06-17
WO2021094440A1 (fr) 2021-05-20

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