Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
  • D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
  • D21C9/001—Modification of pulp properties
  • D21C9/002—Modification of pulp properties by chemical means; preparation of dewatered pulp, e.g. in sheet or bulk form, containing special additives
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08B—POLYSACCHARIDES; DERIVATIVES THEREOF
  • C08B15/00—Preparation of other cellulose derivatives or modified cellulose, e.g. complexes
  • C08B15/02—Oxycellulose; Hydrocellulose; Cellulosehydrate, e.g. microcrystalline cellulose
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08B—POLYSACCHARIDES; DERIVATIVES THEREOF
  • C08B15/00—Preparation of other cellulose derivatives or modified cellulose, e.g. complexes
  • C08B15/10—Crosslinking of cellulose
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
  • C08J5/18—Manufacture of films or sheets
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L1/00—Compositions of cellulose, modified cellulose or cellulose derivatives
  • C08L1/02—Cellulose; Modified cellulose
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L1/00—Compositions of cellulose, modified cellulose or cellulose derivatives
  • C08L1/02—Cellulose; Modified cellulose
  • C08L1/04—Oxycellulose; Hydrocellulose, e.g. microcrystalline cellulose
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
  • D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
  • D21C9/001—Modification of pulp properties
  • D21C9/007—Modification of pulp properties by mechanical or physical means
• • 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
  • 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
  • D21H19/34—Coatings without pigments applied in a form other than the aqueous solution defined in group D21H19/12 comprising cellulose 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
  • D21H27/00—Special paper not otherwise provided for, e.g. made by multi-step processes
  • D21H27/10—Packing paper
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/70—Other properties
  • B32B2307/724—Permeability to gases, adsorption
  • B32B2307/7242—Non-permeable
  • B32B2307/7244—Oxygen barrier
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B82—NANOTECHNOLOGY
  • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
  • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites

Definitions

• the present invention relates to a method for manufacturing at least one layer of a film.
• MFC microfibrillated cellulose
• Aulin et al. Oxygen and oil barrier properties of microfibrillated cellulose films and coatings, Cellulose (2010) 17:559-574, Lavoine et al., Microfibrillated cellulose - Its barrier properties and applications in cellulosic materials: A review, Carbohydrate polymers 90 (2012) 735-764, Kumar et al., Comparison of nano- and microfibrillated cellulose films, Cellulose (2014) 21 :3443-3456), whereas the gas barrier properties are very dependent on the moisture or the relative humidity in the surrounding environment. Therefore, it is quite common that MFC films have to be coated with a polymer film to prevent moisture or water vapor to swell and disrupt the MFC film.
• EP2554589A1 where MFC dispersion was modified with silane coupling agent.
• the EP2551 104A1 teaches the use of MFC and polyvinyl alcohol (PVOFI) and/or polyuronic acid with improved barrier properties at higher relative humidity (RFI).
• An alternative solution is to coat the film with a film that is non-water-soluble and/or having a low water vapor transmission rate.
• the JP2000303386A discloses e.g. latex coated on MFC film, while
• EP2371892A1 claims cross- linking MFC with metal ions, glyoxal, glutaraldehyde and/or citric acid, respectively.
• Another way to decrease the moisture sensitivity of cellulose is to chemically modify the cellulose with sodium periodate to obtain dialdehyde cellulose (DAC).
• DAC dialdehyde cellulose
• a barrier film with improved moisture resistant can be produced.
• the barrier properties at high relative humidity is better with an increased degree of oxidation (D.O.) of the DA-MFC, however the strain-at-break decreases with increased D.O., which is a disadvantage for barrier films e.g. since they are to form a stable, non- disrupted layer through a converting process.
• DA- MFC dialdehyde cellulose
• D.O. dialdehyde cellulose
• second degree of oxidation being lower than the first
• a barrier film may be obtained which has improved ductility while maintaining its good oxygen barrier property, compared to known films comprising DA-MFC.
• a fiber based barrier film is provided which combines good oxygen barrier properties with improved ductility and higher strain at break.
• the oxygen transmission rate (OTR) of a barrier film improves with an increased amount of aldehyde groups in the cellulose content of the film suspension.
• OTR oxygen transmission rate
• barrier films comprising DA-MFC with a high D.O. leads to fragile films with a low strain at break, which is disadvantageous when using the film e.g. for producing packages for oxygen-sensitive food products.
• the present invention solves this problem by combining DA-MFC with a high D.O. with DA-MFC having a low D.O. in a mixture used for film forming, thereby achieving a film with good oxygen barrier properties and high strain at break.
• the term“high D.O.” is referring to a D.O. of between 30 - 60%
• the term“low D.O.” is referring to a D.O. of between 15 - 25%.
• the cellulose derivative“dialdehyde cellulose” can be produced by chemically modifying the cellulose with sodium periodate thereby selectively cleaving the C2-C3 bond of the anhydroglucose unit in the cellulose chain, forming two aldehyde groups at said location.
• the term“degree of oxidation” is understood to refer to the portion of the total number of anhydroglucose units that undergo said reaction (forming the two aldehydes). The degree of oxidation is given in %.
• the cellulose fibers referred to in the present application may originate from wood cellulose fibers, both from hardwood or softwood fibers. It can also be made from microbial sources, agricultural fibers such as wheat straw pulp, bamboo, bagasse, cotton or other non-wood fiber sources. It is preferably made from pulp including pulp from virgin fiber, e.g. mechanical, chemical and/or thermomechanical pulps. It can also be made from broke or recycled paper.
• oxygen transmission rate means a measure of the amount of oxygen gas that passes through the film over a given time period, that is: cm 3 /m 2 /24h.
• OTR oxygen transmission rate
• a batch process may be used, wherein at least two suspensions of cellulose fibers are pre-oxidized to dialdehyde cellulose having different degrees of oxidation (i.e. high and low D.O.) before being mixed together and then m icrofibril lated by means of mechanical treatment.
• the method for manufacturing at least one layer of a film comprises the steps of:
• microfibrillated cellulose
• the method according to the invention comprises mechanically treating the dialdehyde cellulose fibers in the mixture, whereby microfibrillated cellulose is obtained.
• the microfibrillated cellulose resulting from the mechanical treatment and referred to above includes the microfibrillated dialdehyde cellulose, DA-MFC.
• the mechanical treatment may be carried out by means of a refiner, grinder, homogenizer, colloider, friction grinder, ultrasound sonicator or fluidizer. All conventional homogenizers and fluidizers available may be used, such as Gaulin
• microfibrillate refers to a mechanical treatment whereby microfibrillated (cellulose) fibers are obtained.
• the method for manufacturing at least one layer of film comprises the steps of:
• the process parameters are adjusted such that the withdrawn mixture comprises at least one portion with a degree of oxidation of cellulose between 30 - 60%, and at least one second portion with a degree of oxidation between 15 - 25%;
• said continuous process also comprises the step of continuously or stepwise feeding new oxidizing agent into the reaction chamber to compensate for the oxidizing agent that is consumed in the chemical reaction process, and also for replacing the oxidizing agent that is withdrawn from the reaction chamber along with the dialdehyde cellulose mixture.
• dialdehyde cellulose fibers in said mixture mechanically treating the dialdehyde cellulose fibers in said mixture to microfibrillated dialdehyde cellulose;
• the present invention is based on the idea of controlling oxidation of cellulose fibers in such a way that a suspension of dialdehyde cellulose is achieved which comprises at least a portion of dialdehyde cellulose having a high D.O. and at least another portion of dialdehyde cellulose having a low D.O.
• the method for manufacturing at least one layer of a film comprises the steps of: providing a suspension comprising cellulose fibers;
• said suspension after oxidation comprises at least one portion of dialdehyde cellulose with a first degree of oxidation, and at least a second portion of dialdehyde cellulose with a second degree of oxidation, wherein said second degree of oxidation is lower than said first degree of oxidation, thus acquiring a mixture of dialdehyde cellulose fibers comprising at least two different degrees of oxidation;
• dialdehyde cellulose fibers in said mixture mechanically treating the dialdehyde cellulose fibers in said mixture to microfibrillated dialdehyde cellulose;
• said first degree of oxidation is between 30 - 60%, and said second degree of oxidation is between 15 - 25%.
• the method further comprises a step of adding native microfibrillated cellulose (MFC) to the mixture before applying said mixture to the substrate, preferably adding native MFC to the mixture before mechanically treating the dialdehyde cellulose fibers to microfibrillated dialdehyde cellulose.
• MFC microfibrillated cellulose
• native MFC is added to the mixture of dialdehyde cellulose which comprises high and low D.O., so that the resulting mixture thereafter comprises dialdehyde cellulose of a first degree of oxidation, dialdehyde cellulose of a second degree of oxidation, and native
• microfibrillated cellulose The resulting mixture is subsequently mechanically treated to obtain microfibrillated dialdehyde cellulose, i.e. the dialdehyde cellulose fibers are fibrillated to DA-MFC in the presence of native MFC. Adding native MFC before homogenization (or other corresponding
• the mixture comprises between 5 - 85 % by weight of cellulose fibers oxidized to the first degree of oxidation, between 5 - 85 % by weight of cellulose fibers oxidized to the second degree of oxidation, and 10 - 50 % of native microfibrillated cellulose (MFC), based on the total fiber weight of the mixture.
• MFC native microfibrillated cellulose
• the dry content of the mixture applied to the substrate is between 1-10% by weight.
• the substrate is a polymer or metal substrate onto which the mixture is casted.
• the cast coated fibrous web can be dried in any conventional manner and thereafter optionally peeled off from the substrate. It may be possible to cast or coat more than one layer onto the substrate forming a multilayer film. It is possible to produce a film comprising more than one layer wherein at least one of the layers comprises the mixture according to the invention.
• the substrate may also be a porous wire of a paper making machine, i.e. any kind of paper making machine known to a person skilled in the art used for making paper, paperboard, tissue or any similar products.
• the substrate may also be a paper or paperboard product to which the mixture is applied to form a coated product. In one aspect of the invention, the substrate is heated to 50 - 200°C upon applying said mixture thereon.
• said method further comprises the step of pressing the film after drying. It has been shown that the barrier function of the film is improved if the film is subjected to increased pressure after drying.
• the pressure used is preferably between 40-900kPa and the pressing may last for a period of less than 10 minutes, preferably between 1 second to 10 minutes. It is preferred that the pressing is done at elevated temperatures. Temperatures used during pressing may be between 50-200°C, preferably between 100-150°C.
• the pressing may be done in any conventional equipment such as presses or calenders.
• said mixture further comprises any one of a starch, carboxymethyl cellulose, a filler, retention chemicals, flocculation additives, deflocculating additives, dry strength additives, softeners, or mixtures thereof.
• the invention also comprises a film obtainable by means of any one of the previously mentioned methods.
• the film has a basis weight of less than 50 g/m 2 , preferably between 10-50 g/m 2 .
• the at least one layer of the film has an oxygen transmission rate in the range of from 0.1 to 300 cc/m 2 /24h according to ASTM F-1927, at a relative humidity of 50 % at 23 ° C and/or at a relative humidity of 90% at 38 ° C.
• the at least one layer of film has a strain at break of at least 1.5%, preferably 4%, more preferably 6%.
• a film comprising more than one layer wherein at least one of the layers comprises the mixture according to the invention. It may also be possible that more than one layer of the film comprises the mixture according to the invention. It may also be possible that one or more layers of the film only comprises native microfibrillated cellulose, i.e. which does not comprise microfibrillated dialdehyde cellulose (DA-MFC).
• D-MFC microfibrillated dialdehyde cellulose
• the film may comprise two, three, four, five, six, seven, eight, nine, ten or more layers.
• the film according to the invention may be used in a package material e.g. intended for food stuff.
• a package material may e.g. comprise a base material and a barrier film according to the present invention laminated thereto.
• the base material may include, but is not limited to, paper, cardboard, paperboard, fabric, plastic, polymer film, metal, composites and the like.
• the package material may be in the form of a multilayer laminate which, in addition to the base layer and the barrier film comprising DA-MFC, also includes one or more laminate layers such as polyethylene coating, a polyvinyl alcohol coating and/or a metallized film layer.
• the present invention also comprises the use of a film according to any one of the previously mentioned aspects, as an oxygen barrier film.
• the method according to the present invention relates to a method for manufacturing at least one layer of a barrier film having at least oxygen barrier properties, said method comprising providing a suspension with microfibrillated dialdehyde cellulose having a first degree of oxidation (D.O.) mixed with microfibrillated dialdehyde cellulose having at least a second D.O., wherein the second D.O. is lower than said first D.O., applying said mixture to a substrate to form a fibrous web and drying said web to form at least one layer of film.
• D.O. first degree of oxidation
• a film can be formed which has improved ductility while maintaining a good oxygen barrier property.
• a mixture in accordance with the present invention i.e. comprising at least one portion with DA-MFC having a high D.O., and at least one portion with DA-MFC having a low D.O.
• two suspensions comprising cellulose fibers are firstly oxidized separately to different D.O. (high and low respectively), whereafter they are mixed together to form a mixture.
• dialdehyde cellulose in the mixture is then mechanically treated in such way that it is microfibrillated, for example by a homogenizer or in any other way such that fibrillation occurs to produce microfibrillated dialdehyde cellulose.
• microfibrillated dialdehyde cellulose in this context means a dialdehyde cellulose treated in such way that it is microfibrillated.
• Flereby fibrils in a width of less than 200 pm are obtained, such as fibrils in the width range of between 1 nm - 200 pm, and the at least one layer of the film is then formed by applying said microfibrillated mixture to a substrate to form a fibrous web, and drying said web to form at least one layer of said film.
• the drying of said web may be done in any conventional way known to the skilled person.
• the dry content of the at least one layer of the film after drying is preferably above 95% by weight.
• Another way of acquiring the suspension in accordance with the present invention is to oxidize the cellulose fibers of the same suspension to different degrees (high and low respectively).
• a volume of suspension comprising cellulose fibers is added to a continuous stirred-tank reactor (also called a flow reactor tank or a mixer reaction chamber), and oxidation is initiated for instance by means of subjecting said suspension to sodium periodate in a conventional manner known to the skilled person.
• suspension is performed in the reactor tank, and in accordance with the principles of a continuous process, a certain volume of cellulose-containing suspension is continuously fed into the tank and mixed with the suspension already present therein to form a mixture.
• a certain volume of the mixed suspension is also continuously withdrawn from the tank, and oxidation of the withdrawn mixture is interrupted by means of washing away the oxidizing agent.
• This procedure allows for adjustment of process parameters including e.g a) mixing intensity of the suspension inside the reaction chamber, b) the feeding rate of new suspension into the chamber, c) the rate of withdrawal of mixture out of the chamber, d) temperature in the reactor, e) pulp consistency of pulp that is fed into the reactor and f) ratio of the concentration of oxidizing agent vs. pulp consistency in wt%.
• a continuous process including oxidation of cellulose fibers results in a mixture of dialdehyde cellulose with a wide spread of D.O.
• adjusting a continuous process for oxidation of cellulose fibers so that the mean D.O. is between 10 - 50% provides a mixture with the desired spread of D.O. for forming a film with good barrier properties and with improved strain at break.
• the mixture withdrawn from the continuous reactor tank comprises at least one portion with a degree of oxidation of cellulose between 30 - 60%, and at least one second portion with a degree of oxidation between 15 - 25%.
• An example of carrying out a continuous process according to the present invention is as follows.
• a continuous stirred tank reactor is provided with an inflow of sodium periodate and cellulose pulp.
• the temperature in the reactor is preferably between 20 - 70°C, preferably 40 - 60°C and even more preferably 45 - 50°C.
• the continuous stirred reactor tank has design criteria such as dwell time, volume and feed based on reaction rate, known to the person skilled in the art.
• the dialdehyde cellulose fibers of the mixture withdrawn from the reactor tank are thereafter mechanically treated (i.e. microfibrillated) to obtain microfibrillated dialdehyde cellulose (DA-MFC).
• D-MFC microfibrillated dialdehyde cellulose
• Said mixture is applied to a substrate to form a fibrous web which is dried to form at least one layer of film. It is within the scope of the invention to add native MFC to the mixture before microfibrillation, so that such native MFC is present when the dialdehyde cellulose fibers are mechanically treated to DA-MFC.
• the degree of oxidation of the dialdehyde cellulose may be determined according to the following description: after the dialdehyde cellulose reaction, the amount of C2-C3 bonds in the cellulose that are converted to dialdehydes are measured. The degree of oxidation is the amount of C2-C3 bonds that are converted compared to all C2-C3 bonds. This is measured with a method by H. Zhao and N.D. Heindel,“Determination of Degree of Substitution of Formyl Groups in Polyaldehyde Dexran by the Flydroxylamine Hydrochloride
• VNaOH the amount of sodium hydroxide needed to reach pH 4 (I)
• M w 160 g/mol, which is the molecular weight of the dialdehyde cellulose unit
• the mixture may further comprise additives, preferably any one of a starch, carboxymethyl cellulose, a filler, retention chemicals, flocculation additives, deflocculating additives, dry strength additives, softeners, or mixtures thereof. It may be possible to add additives that will improve different properties of the mixture and/or the produced film. It may be possible to add the additive to the first suspension, the second suspension and/or to the mixture. It has been shown that the use of a softener, such as sorbitol, glycerol, polyethylene glycol, sorbic acid, propylene glycol, erythritol, maltitol or polyethylene oxides, will modify and improve some of the mechanical properties of the film, especially the stretch at break properties.
• a softener such as sorbitol, glycerol, polyethylene glycol, sorbic acid, propylene glycol, erythritol, maltitol or polyethylene oxides
• the amount of sorbitol used is preferably between 1 -20% by dry weight of the film.
• native microfibrillated cellulose MFC
• the native microfibrillated cellulose is microfibrillated cellulose produced from mechanical, thermomechanical or chemical pulp, preferably produced from Kraft pulp.
• the native MFC is chemically unmodified, i.e. non-oxidized.
• the microfibrillated cellulose preferably has a Schopper Riegler value (SR°) of more than 90.
• the MFC may have a Schopper Riegler value (SR°) of more than 93.
• the dry solid content of this kind of web, before disintegrated and measuring SR, is less than 50 % (w/w).
• the Schopper Riegler value it is preferable to take a sample just after the wire section where the wet web consistency is relatively low.
• paper making chemicals such as retention agents or dewatering agents, have an impact on the SR value.
• the SR value specified herein, is to be understood as an indication but not a limitation, to reflect the characteristics of the MFC material itself.
• Microfibrillated cellulose (including microfibrillated dialdehyde cellulose) shall in the context of the patent application mean a nano scale cellulose/dialdehyde cellulose particle fiber or fibril with at least one dimension less than 200 nm or less than 100 nm.
• MFC comprises partly or totally fibrillated cellulose or lignocellulose fibers.
• the liberated fibrils have a diameter less than 200 nm, or 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 (see e.g.
• Chinga-Carrasco G., Cellulose fibres, nanofibrils and microfibrils, : The morphological sequence of MFC components from a plant physiology and fibre technology point of view, Nanoscale research letters 2011, 6:417), while it is common that the aggregated form of the elementary fibrils, also defined as microfibril ( Fengel , D., Ultrastructural behavior of cell wall polysaccharides, Tappi J., March 1970, Vol 53, No. 3.), is the main product that is obtained when making MFC e.g. by using an extended refining process or pressure- drop disintegration process. Depending on the source and the manufacturing 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 fibers, i.e. protruding fibrils from the tracheid (cellulose fiber), and with a certain amount of fibrils liberated from the tracheid (cellulose fiber).
• MFC Middle-MediaCardion cellulose
• fibrillated cellulose cellulose
• nanofibrillated cellulose fibril aggregates
• nanoscale cellulose fibrils cellulose nanofibers
• cellulose nanofibrils cellulose nanofibrils
• cellulose microfibrils fibrillated cellulose
• nanofibrillated cellulose fibril aggregates
• nanoscale cellulose fibrils nanoscale cellulose fibrils
• cellulose nanofibers cellulose nanofibers
• cellulose nanofibrils cellulose nanofibrils
• cellulose microfibrils fibrillated cellulose
• nanofibrillated cellulose fibril aggregates
• nanoscale cellulose fibrils cellulose nanofibers
• cellulose nanofibrils cellulose nanofibrils
• 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 (1 -5 wt%) when dispersed in water.
• the cellulose fiber is preferably fibrillated to such an extent that the final specific surface area of the formed MFC is from about 1 to about 200 m2/g, or more preferably 50-200 m2/g when determined for a freeze-dried material with the BET method.
• MFC multi-pass refining
• pre-hydrolysis followed by refining or high shear disintegration or liberation of fibrils.
• One or several pre-treatment step is usually required in order to make MFC manufacturing both energy efficient and sustainable.
• the cellulose fibers of the pulp to be supplied may thus be pre-treated
• nanofibrillar cellulose may contain some hemicelluloses; the amount is dependent on the plant source.
• MFC includes, but is not limited to, the new proposed TAPPI standard W13021 on cellulose nanofibril (CNF) defining a cellulose nanofiber material containing multiple elementary fibrils with both crystalline and amorphous regions, having a high aspect ratio with width of 5-30nm and aspect ratio usually greater than 50.
• CNF cellulose nanofibril
• Dialdehyde cellulose with a degree of oxidation of 20% was mixed with dialdehyde cellulose with a degree of oxidation of 40%, and with standard homogenized native MFC, forming a mixture.
• the native MFC content was 20wt-% by total dry weight of the mixture.
• the mixture was mechanically treated in a homogenizer to form microfibrillated dialdehyde cellulose mixed with native MFC. Films were prepared on a heated metal plate. A first layer of 20 g/m 2 of 100% standard MFC was firstly applied, and then a second layer of 20 g/m 2 of the DA-MFC mixture was applied on top of the first layer.
• suspensions comprising DA-MFC with one D.O. were also performed, corresponding to trial numbers 3 and 4.
• the strain at break was measured by means of a standard tensile test (ISO 1924-2 with a span length of 20 mm), wherein the film to be tested was stretched with test speed of 2 mm/minute until a point where it ruptured. The strain at break then corresponds to the percent elongation when rupturing, i.e. to what extent in % the film deforms without breaking upon being subjected to stretching.
• Fig. 1 shows a graph of the results of the OTR measurements at 23°C and 80% RH, where the OTR is plotted against average D.O. of the mixtures used.
• Fig. 2 shows a graph of the results of the tensile tests, where the strain is plotted against average D.O. of the mixtures used.
• the mixture comprised 20wt-% by total dry weight of the mixture of native MFC; 60wt-% of DA-MFC with a D.O. of 20%; and 20wt-% of DA-MFC with a D.O. of 40%.
• the mixture comprised 20wt-% by total dry weight of the mixture of native MFC; 40wt-% of DA-MFC with a D.O. of 20%; and 40wt-% of DA-MFC with a D.O. of 40%.
• the mixture comprised 20wt-% by total dry weight of the mixture of native MFC; and 80wt-% of DA-MFC with a D.O. of 20%.
• the mixture comprised 20wt-% by total dry weight of the mixture of native MFC; and 80wt-% of DA-MFC with a D.O. of 40%.
• suspensions comprising a mixture of DA- MFC with two different D.O. (with high and low degrees of oxidation respectively), provides a higher strain at break compared to suspensions comprising DA-MFC with only one D.O.
• suspensions comprising a mixture of DA-MFC with two different D.O. prove to be good oxygen barriers, also when compared to suspensions comprising DA-MFC with only one D.O.

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• 2018
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  • 2019-03-06 WO PCT/IB2019/051783 patent/WO2019171279A1/en active Application Filing
  • 2019-03-06 EP EP19713220.2A patent/EP3762538A1/de not_active Withdrawn
  • 2019-03-06 JP JP2020546918A patent/JP2021517216A/ja not_active Abandoned

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