Cellulose microparticle composition

Abstract

The present invention refers to cellulose microparticle powder, a dispersion, a film, sheet, coating or capsule of said cellulose particles, and a method for producing a powder of cellulose microparticles.

Description

[0001] CELLULOSE MICROPARTICLE COMPOSITION

[0002] The present invention refers to cellulose microparticle powder, a dispersion, a film, sheet, coating or capsule of said cellulose particles, and a method for producing a powder of cellulose microparticles.

[0003] Due to enhanced environmental consciousness and the awareness of the necessity to provide alternatives to the use of petroleum resources, there is a focus on providing materials utilizing bio-degradable and reproducible natural fibers. Among natural fibers, fibrous cellulose having a fiber diameter of 10 pm or more up to 100 pm, in particular, wood-derived fibrous cellulose (pulp) have been mainly used for preparing paper products so far.

[0004] Cellulose as such is not dissolvable in water, and even dispersion can only be maintained by constant stirring. To make cellulose water-dissolvable commonly chemical derivatization of the cellulose hydroxy groups is carried out to allow separation of the cellulose fibers, rendering them water soluble. Another possibility is very fine grinding of the cellulose, up to a nano scale.

[0005] Fine fibrous cellulose, having a fiber diameter of less than 1 pm, is known as nanofibrous cellulose. Such fine fibrous cellulose can be used as novel materials, and the intended use thereof has been highly diversified. For example, the development of sheets, resin composites and thickeners, comprising the nano-fine fibrous cellulose, has been promoted.

[0006] Fibrous cellulose can be produced by performing a decomposing treatment on cellulose fibers. Since cellulose fibers are strongly connected via hydrogen bonds, intensive treatment is necessary to obtain fine fibrous cellulose. To decrease the effort, it is presently considered effective to apply a pre-treatment e.g. a chemical treatment or a biological treatment, in addition to performing a defibration treatment.

[0007] On one hand, if e.g. ionic functional groups are introduced into cellulose fibers by chemical treatment, the cellulose fibers can be easily fibrillated, and dispersion stability is also enhanced. On the other hand, chemical treatment is also cost and time intense, and the environmental burden is undesired. In addition, problems such as deterioration or yellowing of cellulose fibers may occur.

[0008] EP 4 155457 A1 describes that the removal of functional groups from fine fibrous cellulose in a slurry state after completion of fibrillation may reduce transparency, and also that the removal of functional groups from fine fibrous cellulose in a sheet state may result in coloring. In order to solve such problems, EP 4 155 457 A1 considers to enhance transparency and suppress coloring by setting the fiber width of the fine fibrous cellulose to be 1 to 10 nm and decreasing the amount of any substituent in the fine fibrous cellulose to less than 0.5 mmol / g. Liyuan Zhang et al. describe in Material Science Forum Vol. 654-656 (2010), pp. 1760-1763 the preparation and characterization on cellulose nanofiber films, wherein said nanofibers are prepared via a wet ball milling procedure.

[0009] EP 1 036 799 A1 refers to a highly stable distribution of spherical cellulose particles having an average particle size of not more than 2 pm.

[0010] US 2021 / 0207324 A1 discloses the preparation of a cellulose oxygen barrier film from microfibrillated cellulose having a broad size distribution.

[0011] The present invention refers to a cellulose microparticle powder, comprising a composition of cellulose particles, said cellulose particles having a volume-based average mean particle size, determined by laser diffractometry, of more than 1 pm and up to 30 pm, preferably 2 to 25 pm, more preferred 3 to 20 pm even more preferred 4 to 15 pm, wherein no particles are comprised in the composition having a particle size of >100 pm, said composition comprises at least two morphologically differing fractions F1 and F2 of cellulose particles, wherein a first fraction (F1 ) is represented by fibrous particles having an elongation of 0.2 or less, in particular 0.2 to 0.1 , and a second fraction (F2) is represented by spherical particles having an elongation of higher than 0.2, wherein the elongation is the ratio of the average diameter of the particle to the maximum length of the particle, wherein fraction (F2) of spherical particles represents at least 50 % of the number of the particles.

[0012] According to the invention the cellulose preferably is native cellulose. With “native cellulose” is meant that the cellulose chains have no intentionally / artificially introduced chemical side groups. Of course even in nature cellulose can have any derivatization at any of the hydroxy groups, thus, here “native cellulose” is defined as having less than 0.05 mmol / g, preferably less than 0.02 mmol / g, even mor preferred less than 0.01 mmol / g chemical derivatization compared to the chemical formula of cellulose(Ci2H2oOio)n, wherein n is an integer greater than 3 and up to infinity.

[0013] Said cellulose can be obtained from any plant, e.g. from wood, cotton or grass, in particular from wood pulp or cotton, but it also can be re-isolated from cellulose containing remainder or waste, e.g. paper waste, remainders of textile fabrication or fabrics or from any other suitable cellulose-containing material. The cellulose grades of purified cellulose commonly offered on the market for derivatization is readily suitable. Microcrystalline Cellulose (MCC) may also be used, however, is less preferred. The volume fraction of the respective type of particles of cellulose can be determined by measuring shape parameters including a length of fiber (LEFI), a diameter of fiber (DIFI), an elongation, an aspect ratio, and a circularity, by the dynamic image analysis. The dynamic image analysis is a method in which images of particles dispersed in a fluid such as a gas or a solvent are continuously recorded and are binarized and analyzed to obtain a particle diameter or a particle shape. The analysis can be performed by using, for example, a dynamic image analysis type particle diameter distribution analyzer, QICPIC (e.g. manufactured by Sympatec GmbH).

[0014] The LEFI is defined as the length of the longest direct path that connects the ends of the particle within the contour of the particle, The DIFI is defined as the minor diameter of a particle, and is calculated by dividing the projection area of the particle by the sum of all lengths of the fiber branches of the particle. The elongation is a ratio of a diameter of fiber (DIFI) to LEFI (DIFI / LEFI) of the particle.

[0015] Particle size and shape (LEFI, DIFI and EQPC) of a particulate cellulose can be determined by a high-speed image analysis method which combines particle size and shape analysis of sample images. An image analysis method for complex powders is described in: W. Witt, U. Kohler, J. List, Current Limits of Particle Size and Shape Analysis with High Speed Image Analysis, PARTEC 2007. A high-speed image analysis system is commercially available from Sympatec GmbH, Clausthal- Zellerfeld, Germany as dynamic image analysis (DIA) system QICPIC™. The system analyses the shape of the particles and takes potential curliness of the particles into account. It provides a more accurate measurement of true particle sizes (LEFI, DIFI and EQPC) than other methods. The dynamic image analysis (DIA) system QICPIC™ is described in more detail by Witt, W., Kohler, U., List, J.: Direct Imaging of very fast Particles Opens the Application of Powerful (dry) Dispersion for Size and Shape Characterization, PARTEC 2004, Nuremberg, Germany.” The high-speed image analysis system is useful for measuring among others the following dimensional parameters of particles:

[0016] The EQPC (Equivalent Projected Circle Diameter) of the particle is defined as the diameter of a circle that has the same area as the projection area of the particle. The EQPC (50,3) is the median diameter of a Circle of Equal Projection Area and is defined as follows: All particle size distributions, e.g. the EQPC can be displayed and applied as number (0), length (1 ), area (2) or volume (3) distribution. The volume distribution of the EQPC is calculated as cumulative distribution Q3. The volume distribution within the diameter of a Circle of Equal Projection Area value EQPC 50,3 is designated by the number 3 after the comma. The designation 50, reflecting the median value, stands for 50% of the EQPC of particle distribution being smaller than the given value in pm and 50% being larger. The 50% EQPC value is calculated by the image analyzer software. A high-speed image analysis system is commercially available from Sympatec GmbH, as dynamic image analysis (DIA) system QICPIC™, referred to above.

[0017] LEFI: The particle length LEFI is defined as the longest direct path that connects the ends of the particle within the contour of the particle. "Direct" means without loops or branches. For the purpose of the present invention the median LEFI is based on the volume distribution of all particles in a given sample of a particulate MCC. The median LEFI means that 50% of the LEFI of the particle distribution is smaller than the given value in pm and 50% is larger.

[0018] DI Fl: The particle diameter is calculated by dividing the projection area by the sum of all lengths of the branches of the particle skeleton. DIFI is calculated automatically by the software PAQXOS of the dynamic image analysis (DIA) system QICPIC™. For the calculation of DI Fl the software PAQXOS is applying this method to those particles only that are completely within the image frame. For the purpose of the present invention the median DIFI is based on the volume distribution of all particles in a given sample of a particulate MCC. The median DIFI means that 50% of the DIFI of the particle distribution is smaller than the given value in pm and 50% is larger.

[0019] Bulk density (BD) as used herein is defined as the ratio of apparent volume to mass of the material taken, called untapped bulk density, and also the ratio of tapped volume to mass of material taken, called tapped bulk density. A useful procedure for measuring these bulk densities is described in United States Pharmacopeia 24, Test 616 "Bulk Density and Tapped Density," United States Pharmacopeia Convention, Inc., Rockville, Maryland, 1999.

[0020] The aspect ratio is a ratio (Fmin / Fmax) of minimal Feret diameter (Fmin) to maximal Feret diameter (Fmax). Each particle has an aspect ratio of more than 0 and not more than 1 . The Feret diameter is the distance between two parallel tangent lines that put the particle therebetween. The maximal Feret diameter (Fmax) is the largest distance between pairs of tangent lines to the particle in consideration of all possible orientations by changing the directions from 0 degrees to 180 degrees, and the minimal Feret diameter (Fmin) is a minimal distance between pairs of tangent lines to the particle in consideration of all possible orientations by changing the directions from 0 degrees to 180 degrees.

[0021] The circularity of a particle is a ratio of the perimeter (PEQPC) of a circle that has the same area as the projection area (Ap) of the particle to the perimeter (Preai) of the real particle, and is defined by the following equation. Each particle has a circularity of more than 0 and not more than 1 . A particle having a smaller circularity has a more irregular shape. The EQPC is the diameter of a circle of an equal projection area, and is defined as the diameter of a circle that has the same area as the projection area of the particle, and is also called Heywood diameter.

[0022] Circularity-PEQPc / Preai-2v{square root over (pi-Ap)}ZPreai

[0023] The volume (Vm) of the particles of cellulose can be calculated by the following equation where each fine particle is assumed to be a sphere having a diameter of EQPC. Vm=(pi / 6)x(EQPC)3x / Vm, wherein Nmis the number of all considered particles in a sample, and EQPC is a median EQPC corresponding to the 50 % cumulative value on a number-based cumulative particle diameter distribution curve of the particles.

[0024] As described in the present specification, the cellulose particles in the composition of the invention can be divided, on the basis of shape parameters of particles as LEFI, an elongation, an aspect ratio, and a circularity, into "fibrous particles" fraction F1 and "spherical particles" fraction F2, which are distinguishable from each other, in particular by elongation.

[0025] Fibrous Particles

[0026] Particles having at least one of the following characteristics are falling under the definition of the fibrous particles (F1):

[0027] Particles having an elongation of 0.2 or less, preferably of 0.15 or less, even more preferred of 0.1 or less and / or an aspect ratio of less than 0.5, preferably of 0.4 or less, even more preferred of 0.35 or less and I or a LEFI (length of fiber) of less than 100 pm preferably of less than 60 pm, even more preferred of less than 30 pm, and I or a circularity, of less than 0.7, preferably of 0.6 or less, even more preferred of 0.5 or less.

[0028] The volume (VF) of the fibrous particles of cellulose can be calculated by the following equation wherein each long fibrous particle is assumed to be a cylindrical column having a DIFI as a bottom diameter and an LEFI as a height.

[0029] VF=(pi / 4)x(DIFI)2x(LEFI)xA / F, wherein Npis the number of fibrous particles in the sample, DIFI is a median DIFI corresponding to the 50 % cumulative value on a number-based cumulative particle diameter distribution curve of the fibrous particles, and LEFI is a median LEFI corresponding to the 50 % cumulative value on a number-based cumulative particle diameter distribution curve of the fibrous particles.

[0030] Spherical Particles

[0031] Particles having at least one of the following characteristics are falling under the definition of the spherical particles (F2):

[0032] Particles having an elongation of more than 0.2, preferably of 0.3 or more, even more preferred of 0.4 or more, even more preferred 0.5 or more, or even 0.6 or more, and / or an aspect ratio of 0.5 or more, preferably of 0.6 or more, even more preferred of 0.7 or more and I or a LEFI (length of fiber) of less than 40 pm preferably of less than 30 pm, even more preferred of less than 20 pm, and / or a circularity, of 0.7 or more, preferably of 0.8 or more, even more preferred of 0.9 or more.

[0033] The volume (Vs) of the spherical particles of the cellulose can be calculated by the following equation where each spherical particle is assumed to be a sphere having a diameter of EQPC.

[0034] Vs=(pi / 6)x(EQPC)3x / Vs, wherein Ns is the number of spherical particles in the sample, and EQPC is a median EQPC corresponding to the 50 % cumulative value on a number-based particle diameter cumulative distribution curve of the spherical particles.

[0035] In the following description any reference to “the cellulose powder”, “the cellulose powder composition”, or “the cellulose microparticle powder” refers to the cellulose powder consisting essentially of the fractions F1 and F2 as described herein, without any further additives. The cellulose powder may comprise some amount of nano-fibrous cellulose particles, i.e. particles below 1 pm average diameter or fiber length, but this amount preferably is kept at less than 10 wt.% or less than 8 wt.%, less than 6 wt.% or less than 4 wt.%, less than 2 wt.%, preferably less than 1 .5 wt.%, more preferred less than 1 wt.%, even more preferred less than 0.5 wt.% of cellulose nanofibers (particles having at least one dimension in the nanometer scale). Most preferred the composition does not comprise any nanofibers.

[0036] The term “composition of cellulose particles” refers either to the cellulose powder composition in dried form, or to a suspension / dispersion of said cellulose powder in a solvent, preferably in water, e.g. a cellulose-in-water slurry, wherein the cellulose particles in said slurry have the characteristics as defined herein.

[0037] The cellulose powder composition of the present invention comprises - based on the number of particles - a higher amount of spherical particles according to (F2) than fibrous particles according to (F1 ). Thus, the fraction of spherical particles (F2) represents at least 50 % of the number of the particles, preferably at least 55 %, at least 60 %, at least 65 %, at least 70 %, at least 75 %, at least 80 %, or at least 85 % of the particles of the composition. On the other hand, the fraction of fibrous particles (F1 ) represents less than 50 % of the number of the particles, preferably less than 45 %, less than 40 %, less than 35 %, less than 30 %, less than 25 %, less than 20 %, or even less than 15 % of the particles of the composition.

[0038] The volume fraction of each type of particles of the cellulose can be calculated from the following corresponding equation on a basis of the above-defined volumes, Vm, VF, and Vs. Volume fraction of the particles={Vm / (Vm+VF+Vs)}x100 Volume fraction of fibrous particles={VF / (Vm+\ / F+Vs)}x100 Volume fraction of spherical particles={Vs / (Vm+VF+Vs)}x100

[0039] The cellulose powder composition according to the invention preferably has a volume fraction (F1 ) of fibrous particles of less than 50 % of the total volume of the cellulose powder, preferably from 15 to 45 %, more preferably from 20 to 40 % from the standpoint of good flowability and coalescence performance.

[0040] The cellulose powder composition according to the invention preferably has a volume fraction (F2) of spherical particles of from 50 to 85 %, preferably from 55 to 80 %, more preferably from 60 to 80 % of the total volume of the cellulose powder from the standpoint of good flowability and coalescence performance.

[0041] The cellulose particles have a volume-based average mean particle diameter, determined by a dry laser diffractometry, of preferably from more than 1 pm and up to 30 pm, preferably 2 to 25 pm, more preferred 3 to 20 pm even more preferred 4 to 15 pm, wherein no particles are comprised in the cellulose powder composition having a particle size of >100 pm. The volume-based average particle diameter means a diameter corresponding to the 50 % cumulative value of a volume-based cumulative particle diameter distribution curve, and it may be measured using e.g. a laser diffraction particle diameter distribution analyzer, for example "Mastersizer 3000" (produced by Malvern Instruments Ltd).

[0042] The particles within the cellulose powder composition have preferably a (volume mean) particle size distribution with D10 in the range of from 0.2 to 1 pm, preferably from 0.3 to 0.8 pm, more preferred from 0.4 to 0.6 pm, D50 of from 2 to 20 pm, preferably from 3 to 15 pm, more preferred from 4 to 10 pm, even more preferred from 4 to 8 pm and D90 of from 10 to 40 pm, preferably 12 to 30 pm, more preferred 15 to 25 pm. The given values can be considered as independent values or in combination, characterizing the cellulose powder composition.

[0043] Cellulose components in the cellulose can be classified into cellulose components and hemicellulose components. A lower percentage of hemicellulose is preferable because yellowing over time or heat yellowing can be suppressed. The percentage of hemicellulose in the cellulose powder composition of the present invention is preferably less than 30 %, more preferably less than 25 %, and further preferably less than 20 wt.%.

[0044] Method for producing cellulose microparticles

[0045] The invention refers also to a method for preparing (a composition of) cellulose particles as defined above comprising the steps:

[0046] (i) adding cellulose containing material to water in a ratio of from 1:2 to 1 :100, preferably in a ratio of from 1 :3 to 1 : 50 , more preferred 1 :4 to 1 :30, even more preferred 1 :5 to 1 :25 and most preferred 1 :6 to 1 :20 (weight / weight),

[0047] (ii) combining the mixture of (i) with grinding balls, wherein preferably the grinding balls are present in a 3-fold to 10-fold, more preferred a 4-fold to 8-fold excess referring to the weight of the mixture of (i),

[0048] (iii) grinding the cellulose containing material in a wet-milling process by means of the grinding balls (i.e. wet ball-milling) to a particle size as defined above,

[0049] (iv) separating the grinding balls from the mixture of (iii).

[0050] According to the invention it is highly preferred that the cellulose raw material is roughly cut into a manageable size (pre-cutting) and then ground in presence of water, thus, in a wetgrinding process. Said wet grinding can be carried out with grinding balls, wherein said grinding balls are added in weight excess to the cellulose material to be ground. Such process is known as ball-milling process. The cellulose containing material used for grinding is preferably the cellulose material as defined above, in particular wood pulp or cotton cellulose, or MCC. The used water can be tap water, but preferably is deionized water.

[0051] The grinding balls can be of any suitable material, e.g. any material commonly used for such a process, like e.g. metal, porcelain, steatite, alumina, zirconia, flint etc., but preferably the grinding balls are made of metal, in particular of steel. The grinding balls can have any suitable size and shape, but preferably the size is in the range of from 0.5 to 10 mm, more preferred from 0.8 to 5 mm, even more preferred 1 to 3 mm.

[0052] The wet ball-milling is carried out under conditions allowing to prepare cellulose microparticles having the characteristics as defined above. For example, the milling can be carried out under the following conditions:

[0053] Milling at 100 to 1000 rpm, preferably at 150 to 850 rpm, more preferred at 200 to 700 rpm, even more preferred 250 to 600 rpm and even more preferred 300 to 500 rpm, dependent from the ratio of cellulose to the grinding balls,

[0054] - Temperature in the range of from 10 to 50°C, 15 to 40°C, 18 to 30°C or 20 to 25°C or 23±2°C (i.e. room temperature), optionally cooling or heating the batch, Grinding for at least 5 or at least 10 min and up to 5 h, at least 15 min and up to 4 h, at least 20 min and up to 3 h or up to 2 h or up to 1 h total grinding time, either with or without any break, Optionally changing the stirring / rolling direction.

[0055] During the process samples can be taken and considered whether the desired characteristics of prepared particles have already been reached.

[0056] After the grinding process the grinding balls are separated from the batches. Separation can be done by any suitable procedure, like sieving, filtering, skimming or allowing to sag, but a filtering method is preferred, e.g. by pouring the whole batch through a web, net or sieve allowing to pass the water and cellulose particles, but holding back the grinding balls.

[0057] Mariko Ago et al. published in Cellulose 11 (2004) pp. 163-167 a crystalline transformation of native cellulose from cellulose I to cellulose II polymorph by ball-milling method with a specific amount of water, which is according to this paper a water content of 30 to 50 wt.% (based on the cellulose slurry of cellulose and water).

[0058] Thus, during the ball-grinding (ball-milling) process according to the invention a conformation change of the cellulose 3D structure might optionally obtained, which is a change from cellulose I configuration to cellulose II configuration. Thus, an optional feature of the cellulose might be the cellulose particles having a content of cellulose II of at least 20 wt.%, preferably at least 30 wt.%, more preferred at least 35 wt.% and even more preferred at least 40 wt.%.

[0059] The cellulose slurry (cellulose dispersion in water after separating the grinding balls) can be either directly used for further applications, or can be spray-dried to obtain a cellulose powder composition according to the invention. The spray-drying procedure is very well known to people skilled in the art and can be carried out under common conditions.

[0060] Spray-drying devices are known in the art. Preferred spray-drying devices are conventional spray-dryers like Mini Spray Dryer B-290 from Buchi Labortechnik AG, Mobile Minor or Production Minor from GEA Group Aktiengesellschaft. Preferably a gas, such as air or nitrogen can be used for spray-drying. The temperature in the spray-drying device preferably is from 100 to 300 °C, more preferably from 150 to 220 °C. The outlet temperature of the spray-drying device, i.e., the temperature in the spray nozzle(s) typically is from 50 to 200 °C, more typically from 70 to 110 °C. During spray drying, the individual polymer particles may become grouped together in small aggregates, but the particles are readily redispersible in water at a later time. The spray-dried powder product has preferably a water content of below 20 wt.%, more preferred less than 15 wt.%, even more preferred less than 10 wt.%.

[0061] The spray-dried cellulose powder composition can comprise agglomerates of the cellulose microparticles as described herein, however, if said cellulose powder composition comprising said agglomerates is added to water and stirred, the agglomerates decompose resulting in the microparticles as described.

[0062] The characteristics of the cellulose microparticles are determined in suspension / dispersion as described above.

[0063] The cellulose powder composition obtainable by spray drying is storable and can be used for a great variance of applications. Very advantageous applications are the preparation of a cellulose film, coating or (mini)capsule. For preparing one of these products, the cellulose powder composition can just be added to water, the batch can be stirred or sheared to prepare a slurry, wherein the cellulose particles correspond to the microparticles according to the invention.

[0064] The slurry of cellulose microparticles according to the invention - either the slurry obtained after separating the grinding balls, or a slurry obtainable by addition of the cellulose powder composition to water - can be used for preparing a film, coating or capsule. For this use a slurry having a water content in the range of 40 to 99 wt.%, preferably 50 to 98 wt.%, more preferred 60 to 97 wt.%, even more preferred 70 to 97 wt.% and most preferred 80 to 95 wt.% water or aqueous solution, referring to the total composition is particularly useful. Either to the dispersion after grinding the cellulose, or to a dispersion prepared from the spray-dried cellulose powder in water a plasticizer can be added, allowing the film, coating or capsule to become more flexible and I or soft. Thus, the slurry can further comprise 0.5 to 25 wt.%, preferably 1 to 20 wt.%, more preferred 2 to 15 wt.% and even more preferred 3 to 10 wt.% of a plasticizer, referring to the total composition.

[0065] Said plasticizer can be selected from glycerol, alkylene glycol mono alkyl ethers, polyalcohols, propylene glycols, ethoxylated or propoxylated ethylene or propylene, glycerol esters, glycerol triacetate, polyethylene glycols, methyl esters and amides and nonionic surfactants, wherein preferably the plasticizer is glycerol.

[0066] The slurry, i.e. said dispersion of cellulose particles according to the invention with or without plasticizer has a viscosity in the range of 10 to 100.000 mPa*s, preferably 20 to 10.000 mPa*s, more preferred 50 to 1.000 mPa*s.

[0067] The present invention refers also to a method for preparing a cellulose film, coating or capsule, comprising the steps: a) preparing a homogeneous dispersion of cellulose particles having the features as defined herein above in water or an aqueous solution, wherein the cellulose particles are present in an amount of from 1 to 20 wt.% of the total weight of said dispersion, b) applying said dispersion onto a smooth I plane surface to prepare a film, or to the surface of a material for coating, in an amount that enables uniform distribution of the dispersion in the form of a closed layer on said surface c) drying the dispersion to allow coalescence of the cellulose particles, wherein drying preferably is carried out up to a water content in the range of 1.5 to 12 wt.%.

[0068] In step a) it is preferred that the cellulose microparticles are present in an amount of from 2 to 18 wt.%, more preferred from 3 to 16 wt.%, even more preferred 4 to 14 wt.% or 5 to 12 wt.%, or even 6 to 10 wt.% of the cellulose slurry.

[0069] In step b) the dispersion of the cellulose microparticles is applied to a surface, said surface can be:

[0070] - a surface allowing the resultant film to be peeled off after drying the cellulose dispersion, e.g. an even, plane, smooth or polished surface, for example made of glass, plastic or metal, or

[0071] - a surface to be coated (e.g. the surface of a pharmaceutical, nutritional, detergent or any other suitable unit dose, like a tablet), or - surface of a pin for preparing cellulose half-shells allowing to be sticked together to a cellulose capsule, or

[0072] - any other suitable surface allowing the formation of a solid layer of cellulose.

[0073] In step (b) the dispersion can be applied to the surface by any of the known coating procedures, e.g. cast coating, spray coating, roll coating, blade coating, curtain coating or printing, and optionally evenly distributing. Further, encapsulation of liquids, thus preparation of mini capsules can be obtained by coacervation in a liquid phase.

[0074] During drying of the cellulose slurry in step c) the cellulose microparticles form a film I layer I capsule (half-shell) by coalescence of the slurry solid compounds. Drying can be carried out in a temperature range of from 10 to 80°C, preferably 20 to 60°C, more preferred 25 to 50°C, preferably by applying air, more preferred by blowing cool or tempered air, particularly drying is obtained by tempered air in a temperature range of from 10 to 50°C, preferably in a range of from 15 to 40°C, 18 to 35°C, 20 to 30 °C or at room temperature (23±2°C).

[0075] The water content of the cellulose film / coating I capsule after drying is preferably in the range of from 1.5 to 12 wt.% based on the dried film / coating / capsule, preferably in the range of from 2 to 10 wt.%, or from 3 to 8 wt.% from the viewpoint of flexibility, elasticity, nonbrittleness and manageability.

[0076] After drying the resulting film or (half) capsule can be drawn from the smooth I plane I polished surface.

[0077] The invention also refers to a cellulose film, coating or capsule prepared from cellulose particles or a dispersion of cellulose particles as described herein.

[0078] The cellulose film, coating or capsule according to the invention preferably has a thickness in the range of from 10 to 300 pm, preferably 20 to 260 pm, more preferred 30 to 240 pm, even more preferred 40 to 200 pm, whereas it is preferred that

[0079] • a cellulose film has a thickness in the range of from 10 to 200pm, preferably 15 to 150 pm, more preferred 20 to 100 pm, even more preferred 30 to 80 pm or 40 to 60 pm,

[0080] • a cellulose coating has a thickness in the range of from 20 to 300pm, preferably 40 to 270 pm, more preferred 60 to 250 pm, even more preferred 70 to 220 pm or 80 to 200 pm, • a cellulose capsule has a thickness in the range of from 30 to 300pm, preferably 50 to 200 pm, more preferred 60 to 180 pm, even more preferred 70 to 150 pm or 80 to 120 pm.

[0081] The cellulose film can be used for packaging, it allows water vapor to pass through, but forms a barrier for aromas, odors and oxygen.

[0082] A cellulose coating can protect the underlying material and its ingredients; can provide a barrier against given conditions; can provide a controlled or modified drug release; provides a touchable surface, thus protects human skin from contact with harmful compounds (e.g. detergent ingredients or allergens); as well as provides a protection for sensitive compounds. The coated material can be a sheet, a unit dose, or a surface of a solid material, without being restricted to the mentioned.

[0083] A cellulose capsule can comprise a solid or a liquid material, e.g. pharmaceutical, nutritional or agricultural powder compositions, or said capsule may comprise a liquid, like an oil, a fragrance, a colorant or a dye (solution). Well known are perfume capsules, oil capsules, dyeing or colorant capsules (e.g. for make-up compositions), but the invention is not restricted to the mentioned.

[0084] Thus, part of the invention is as well a solid dosage form comprising a cellulose coating according to any of the preceding aspects, said solid dosage form preferably can be selected from any unit dosage form, like tablets, pills, dragees, capsules, pearls, granules or suppositories, more preferred pharmaceutical, nutritional, agricultural or detergent tablets.

[0085] Aspects of the invention

[0086] The following features and embodiments are aspects of the present invention:

[0087] 1 . A composition of cellulose particles, said cellulose particles having a volume-based average mean particle size, determined by laser diffractometry, of more than 1 pm and up to 30 pm, preferably 2 to 25 pm, more preferred 3 to 20 pm even more preferred 4 to 15 pm, wherein no particles are comprised in the composition having a particle size of >100 pm, said composition comprises at least two morphologically differing fractions F1 and F2 of cellulose particles, wherein a first fraction (F1 ) is represented by fibrous particles having an elongation of 0.2 or less, in particular 0.2 to 0.1 , and a second fraction (F2) is represented by spherical particles having an elongation of higher than 0.2, wherein the elongation is the ratio of the average diameter of the particle to the maximum length of the particle, wherein fraction (F2) of spherical particles represents at least 50 % of the number of the particles. The composition of cellulose particles according to aspect 1, wherein the spherical cellulose particles of fraction F2 have an aspect ratio, which is a ratio of a minimal Feret diameter to a maximal Feret diameter, of 0.5 or more, and a circularity, which is a ratio of a perimeter (PEQPC) of a circle that has the same area as a projection area to a perimeter (Preai) of a real particle, of 0.7 or more. The composition of cellulose particles according to any preceding aspect, wherein the cellulose particles have a particle size distribution with D10 in the range of from 0.2 to 1 pm, preferably from 0.3 to 0.8 pm, more preferred from 0.4 to 0.6 pm, D50 of from 2 to 20 pm, preferably from 3 to 15 pm, more preferred from 4 to 10 pm, even more preferred from 4 to 8 pm and D90 of from 10 to 40 pm, preferably 12 to 30 pm, more preferred 15 to 25 pm. The composition of cellulose particles according to any of the preceding aspects, wherein said composition comprises less than 10 wt.%, or less than 8 wt.%, less than 6 wt.% or less than 4 wt.%, less than 2 wt.%, preferably less than 1.5 wt.%, more preferred less than 1 wt.%, even more preferred less than 0.5 wt.% of cellulose nanofibers, most preferred the composition does not comprise any nanofibers. The composition of cellulose particles according to any of the preceding aspects, wherein the cellulose has a content of cellulose II of at least 20 wt.%, preferably at least 30 wt.%, more preferred at least 35 wt.% and even more preferred at least 40 wt.%. The composition of cellulose particles according to any of the preceding aspects in form of a powder or a cellulose-in-water slurry. The composition of the preceding aspect, wherein the powder is a spray-dried product, preferably having a water content of below 20 wt.%, more preferred less than 15 wt.%, even more preferred less than 10 wt.%. 8. The composition of cellulose particles according to any of the preceding aspects having a bulk density of from 50 to 600 g / L.

[0088] 9. A method for preparing (a composition of) cellulose particles as defined in any of the preceding aspects comprising the steps:

[0089] (v) adding cellulose containing material to water in a ratio of from 1:2 to 1 :100, preferably in a ratio of from 1 :3 to 1 : 50 , more preferred 1 :4 to 1 :30, even more preferred 1 :5 to 1 :25 and most preferred 1 :6 to 1 :20,

[0090] (vi) combining the mixture of (i) with grinding balls, wherein preferably the grinding balls are present in a 3-fold to 10-fold, more preferred a 4-fold to 8-fold excess referring to the weight of the mixture of (i),

[0091] (vii) grinding the cellulose containing material in a wet-milling process by means of the grinding balls (i.e. wet ball-milling) to a particle size as defined in aspect 1,

[0092] (viii) separating the grinding balls from the mixture of (iii).

[0093] 10. The method of the preceding aspect, wherein the cellulose comprising material is prepurified cellulose material like cellulose pulp or microcrystalline cellulose (MCC).

[0094] 11 . The method of the preceding aspect, further comprising an additional step (v) spray-drying the dispersion of cellulose particles after step (iv).

[0095] 12. The method of the preceding aspect, wherein the step of spray-drying provides a powder having a water content of below 20 wt.%.

[0096] 13. Cellulose particles obtained by a method according to any of aspects 8 to 12.

[0097] 14. A dispersion comprising a composition of cellulose particles as defined in any of the preceding aspects in water or an aqueous solution.

[0098] 15. A dispersion according to the preceding aspect, comprising 40 to 99 wt.%, preferably 50 to 98 wt.%, more preferred 60 to 97 wt.%, even more preferred 70 to 97 wt.% and most preferred 80 to 95 wt.% water or aqueous solution, referring to the total composition.

[0099] 16. A dispersion according to any of the preceding aspects, further comprising 0.5 to 25 wt.%, preferably 1 to 20 wt.%, more preferred 2 to 15 wt.% and even more preferred 3 to 10 wt.% of a plasticizer, referring to the total composition. A dispersion according to the preceding aspect, wherein said plasticizer is selected from glycerol, alkylene glycol mono alkyl ethers, polyalcohols, propylene glycols, ethoxylated or propoxylated ethylene or propylene, glycerol esters, glycerol triacetate, polyethylene glycols, methyl esters and amides and nonionic surfactants, wherein preferably the plasticizer is glycerol. A dispersion according to the preceding aspect, wherein said dispersion has a viscosity in the range of 10 to 100.000 mPa*s, preferably 20 to 10.000 mPa*s, more preferred 50 to 1 .000 mPa*s. Method for preparing a cellulose film, a cellulose coating or cellulose capsules by using a composition of cellulose particles or a dispersion according to any of the preceding aspects. Method according to the preceding aspect comprising the steps: d) preparing a homogeneous dispersion of cellulose particles having the features as defined in any of the preceding aspects in water or an aqueous solution, wherein the cellulose particles are present in an amount of from 1 to 20 wt.% of the total weight of said dispersion, e) applying said dispersion onto a smooth / plane surface to prepare a film, or to the surface of a material for coating, in an amount that enables uniform distribution of the dispersion in the form of a closed layer on said surface, f) drying the dispersion to allow coalescence of the cellulose particles, wherein drying preferably is carried out to a water content in the range of 1.5 to 12 wt.%. Method for preparing a cellulose film according to aspects 19 or 20, further comprising g) drawing the resulting film from the smooth I plane surface. Method according to any of the preceding aspects 19 to 21 , wherein in step (a) either a dispersion obtained in a method according to aspect 9, step (iv) is used and optionally diluted, or a cellulose powder obtained according to aspect 12 is dispersed in water or an aqueous solution. 23. Method according to any of the preceding aspects 19 to 22, wherein in step (b) the dispersion is applied to the surface by casting or spraying and optionally evenly distributing.

[0100] 24. Method according to any of the preceding aspects 19 to 23, wherein in step (c) drying is carried out in a temperature range of from 10 to 80°C, preferably 20 to 60°C, more preferred 25 to 50°C, preferably by applying air, more preferred by blowing cool or tempered air.

[0101] 25. A cellulose film, coating or capsule prepared from cellulose particles or a dispersion according to any of the preceding aspects.

[0102] 26. A cellulose film, coating or capsule according to the preceding aspect, having a thickness in the range of from 10 to 300 pm, preferably 20 to 260 pm, more preferred 30 to 240 pm, even more preferred 40 to 200 pm.

[0103] 27. A cellulose film according to the preceding aspects 25 or 26, having a thickness in the range of from 10 to 200pm, preferably 15 to 150 pm, more preferred 20 to 100 pm, even more preferred 30 to 80 pm or 40 to 60 pm.

[0104] 28. A cellulose coating according to the preceding aspects 25 or 26, having a thickness in the range of from 20 to 300pm, preferably 40 to 270 pm, more preferred 60 to 250 pm, even more preferred 70 to 220 pm or 80 to 200 pm.

[0105] 29. A cellulose capsule according to the preceding aspects 25 or 26, having a thickness in the range of from 30 to 300pm, preferably 50 to 200 pm, more preferred 60 to 180 pm, even more preferred 70 to 150 pm or 80 to 120 pm.

[0106] 30. A cellulose capsule according to any of the preceding aspects, said capsule comprising an oil or fragrance.

[0107] 31 . A solid dosage form comprising a cellulose coating according to any of the preceding aspects, said solid dosage form preferably can be selected from a unit dosage form, like tablets, pills, dragees, capsules, pearls, granules or suppositories, more preferred pharmaceutical, nutritional, agricultural or detergent tablets. 32. A composition of cellulose particles, a film, coating or capsule according to any of the preceding aspects, wherein the cellulose material is obtained from plants, in particular e.g. from wood, cotton or grass, or from textiles or remainders of textile fabrication.

[0108] Figures

[0109] Figure 1 shows the particle size distribution of a cellulose particle composition according to the invention (the obtained powder sample 1 of Example 1) in comparison with the cellulose pulp starting material before the wet milling process according to the invention. In Figure 1 the cellulose powder sample 1 is designated “OPE-21-01-AL-027A".

[0110] Figure 2 shows the release of the active agent paracetamol from uncoated tablets and tablets coated with a cellulose dispersion according to the invention (see Example 3).

[0111] Figure 3 shows the sustained drug release of an active agent (paracetamol) through a film prepared according to the invention having a thickness of about 50 pm (see Example 4)

[0112] Examples

[0113] 1 . Preparation of cellulose particle powder according to the invention

[0114] 1.1. wet mill grinding

[0115] Sample 1 wet: 15.7 g of pre-grinded (by cutting mill) cellulose pulp (Borregaard Blue Bear MV) were added to 234.3 g of DI water and ball-milled in a planetary ball mill (Retsch PM400) with 860 g of grinding balls having a diameter of 2 mm at 400 rpm for 20 min at 25 °C. The circle was 5 min grinding, then 1 min pause, repeat with change of grinding direction. Thereafter the dispersion was split into two portions and to each portion additional 400g of grinding balls with a diameter of 22 mm have been added. Both portions were grinded for additional 10 min. Then the dispersions were separated from the respective balls by filtration.

[0116] Sample 2 wet: 35 g of micro-crystalline cellulose MCC Avicel PH101 were added to 140 g of DI water and ball-milled in a planetary ball mill (Retsch PM400) with 860 g of grinding balls having a diameter of 2 mm at 400 rpm for 30 min at 25°C (10 min grinding, then 45 min pause, 2x repeat with change of grinding direction). Then 100g of water was added to dilute the dispersion to facilitate the separation of the grinding balls by filtration. Sample 3 wet: 6.3 g of pre-grinded (cutting mill) cellulose pulp Borregaard Blue Bear MV were added to 93.7 g of DI water and ball-milled in a Retsch PM400 with 884 g of grinding balls having a diameter of 2 mm at 400 rpm for 10 min at 25°C (5 min grinding, then 1 min pause, repeat with change of grinding direction). Then 100g of water was added to dilute the dispersion to facilitate the separation of the grinding balls by filtration.

[0117] 1.2. Spray drying

[0118] The dispersions of “sample 1 wet” obtained according to 1.1. with 4 wt-% cellulose concentration in water were spray-dried under stirring with a mini-spray dryer (Buchi B290) in suction mode with the following parameters: 175°C temperature, 100% aspirator, 4% pump, noozle cleaner 0-3, spray flow: 50 and a nozzle diameter of 1.5 mm. A cellulose powder sample 1 was obtained.

[0119] Figure 1 shows the particle size distribution of the obtained powder sample 1 in comparison with the starting material pulp (Borregaard). In Figure 1 the cellulose powder sample 1 is designated OPE-21-01-AL-027A.

[0120] 2. Film Formation:

[0121] Two dispersions in water including 4 wt-% of cellulose powder sample 1 (OPE-21-01-AL- 027A) each, were prepared by using an Ultra Turrax high-performance dispersion device. Dispersion A was without any plasticizer, Dispersion B contained glycerol as plasticizer (20 wt-% related to cellulose). 6 samples of each of the dispersions were casted on a glass plate with a 1500 pm blade and dried at 25°C. The films obtained had a thickness of about 50pm and showed a high mechanical strength and flexibility. The films with glycerol were even more flexible.

[0122] The dispersions “sample 2 wet” and “sample 3 wet” as prepared according to 1.1. were diluted to a 5.57 wt-% concentration by adding water using a high-performance dispersing device (Ultra-Turrax IKA T25 basic).

[0123] The obtained dispersions were casted to a glass plate and dried for 10 min at 40°C and thereafter at RT (25°C) until complete dryness overnight. The film resulting from sample 2 dispersion had a film thickness of 120 pm and high mechanical strength and flexibility. The film was insoluble in DI water.

[0124] The same experiment was repeated with the dispersion of sample 2 comprising 10 or 20 wt- % (related to cellulose content) glycerol as plasticizer. The films showed a higher flexibility than the films without glycerol.

[0125] The dispersion of sample 3 was treated the same way, thus, one portion with and one without glycerol and were casted with a 1500pm blade resulting in films having 50pm film thickness with high mechanical strength and flexibility.

[0126] 3. Tablet coating (MCC):

[0127] 3.1 . Preparation of dispersion for coating (sample 4)

[0128] 2 grinding jars were each filled with 35 g of MCC Avicel PH101 and 140 g of DI water and the cellulose was ball-milled in a Retsch PM400 planetary ball mill with each 900 g of grinding balls having a diameter of 2 mm at 400 rpm for 30 min at 25°C (10 min grinding, then 45 min pause, 2x repeat with change of grinding direction). Then the content of the grinding jars was united, 312g of additional water was added and the grinding balls were separated using a 1000 pm sieve.

[0129] 3.2. Coating:

[0130] The obtained dispersion sample 4 was diluted to a 6 wt-% cellulose concentration by adding water using an Ultra-Turrax IKA T25 basic dispersing device.

[0131] To allow consideration of the homogeny of the prepared coating, 0.01 g of the dye Patentblau V sodium were added to 50 g of the 6 wt-% dispersion.

[0132] APAP matrix tablets were used for coating. They consisted of 50% APAP (=paracetamol), 20% Methocel K100M Premium, 1% Aerosil 200, 23% Avicel PH102 and 0.5% Alubra PG- 100.

[0133] 10 Matrix tablets have been coated with the dispersion sample 4 obtained in 3.1 . (being stirred at 250 rpm with a magnetic stirrer) in a lab coater MD2 (Calvea process solutions limited) at 50 °C. Pump speed was 17% (1.51 rpm), fan setting was 60% (12 m / s) and agitator setting was 40% (16 Hz). Spraying of the dispersion was conducted for 1.5 min followed by 3 min of pause to allow the dispersion to dry. This cycle was continued until 8.9 g of the dispersion was sprayed onto the tablets. After coating the tablets were cured at 60°C for 2h. The weight of the film coating on the tablets was about 3.9 wt-%, the coating was homogenous (visible as a continuous blue layer).

[0134] Dissolution of the coated tablets was tested in a UPS II apparatus, in 900 ml USP phosphate buffer 6.8 pH, at 37 °C, under stirring (50 rpm) using a UV photometer at 242 nm to determine the APAP concentration in the dissolution media.

[0135] The coated tablets showed a slower release of the active agent paracetamol (about 25%) compared to the uncoated tablets (see Figure 2).

[0136] 4. Casted film diffusion test

[0137] Cellulose powder sample 1 as obtained according to 1 .2. was used to prepare a 4 wt-% dispersion in water by using a Ultra Turrax device. The dispersion was casted on a glass plate with a 1500 pm blade and dried at 25°C. The film had a thickness of about 50pm.

[0138] The diffusion of APAP through the film was measured as follows:

[0139] A 1 cm2piece of the film was measured in a Franz diffusion cell from PermeGear, Inc. with10 mg / ml APAP in 0.1 N HCI in the upper part of the cell and 0.1 N HCI in the lower part of the cell at 37 °C under stirring (50 rpm). Aliquots were withdrawn from the release medium at each time interval and replaced by equivalent amounts of 0.1 N HCI solution. The amount of drug released was determined spectrophotometrically at 242 nm using a photometer. Maximum amount of APAP diffused through the film results in a concentration of 2 mg / ml of APAP. Sustained drug release was achieved although film thickness was low and release appeared to be zero order (see Figure 3).

Claims

Claims1 . A composition of cellulose particles, said cellulose particles having a volume-based average mean particle size, determined by laser diffractometry, of more than 1 pm and up to 30 pm, preferably 2 to 25 pm, more preferred 3 to 20 pm even more preferred 4 to 15 pm, wherein no particles are comprised in the composition having a particle size of >100 pm, said composition comprises at least two morphologically differing fractions F1 and F2 of cellulose particles, wherein a first fraction (F1 ) is represented by fibrous particles having an elongation of 0.2 or less, in particular 0.2 to 0.1 , and a second fraction (F2) is represented by spherical particles having an elongation of higher than 0.2, wherein the elongation is the ratio of the average diameter of the particle to the maximum length of the particle, wherein fraction (F2) of spherical particles represents at least 50 % of the number of the particles.

2. The composition of cellulose particles according to claim 1 , wherein the spherical cellulose particles of fraction F2 have an aspect ratio, which is a ratio of a minimal Feret diameter to a maximal Feret diameter, of 0.5 or more, and a circularity, which is a ratio of a perimeter (PEQPC) of a circle that has the same area as a projection area to a perimeter (Preai) of a real particle, of 0.7 or more.

3. The composition of cellulose particles according to any preceding claim, wherein the cellulose particles have a particle size distribution with D10 in the range of from 0.2 to 1 pm, preferably from 0.3 to 0.8 pm, more preferred from 0.4 to 0.6 pm, D50 of from 2 to 20 pm, preferably from 3 to 15 pm, more preferred from 4 to 10 pm, even more preferred from 4 to 8 pm and D90 of from 10 to 40 pm, preferably 12 to 30 pm, more preferred 15 to 25 pm.

4. The composition of cellulose particles according to any of the preceding claims, wherein said composition comprises less than 10 wt.%, or less than 8 wt.%, less than 6 wt.% or less than 4 wt.%, less than 2 wt.%, preferably less than 1.5 wt.%, more preferred less than 1 wt.%, even more preferred less than 0.5 wt.% of cellulose nanofibers, most preferred the composition does not comprise any nanofibers.

5. The composition of cellulose particles according to any of the preceding claims in form of a powder or a cellulose-in-water slurry.

6. A method for preparing (a composition of) cellulose particles as defined in any of the preceding claims comprising the steps:(i) adding cellulose containing material to water in a ratio of from 1:2 to 1 :100, preferably in a ratio of from 1 :3 to 1 : 50 , more preferred 1 :4 to 1 :30, even more preferred 1 :5 to 1 :25 and most preferred 1 :6 to 1 :20,(ii) combining the mixture of (i) with grinding balls, wherein preferably the grinding balls are present in a 3-fold to 10-fold, more preferred a 4-fold to 8-fold excess referring to the weight of the mixture of (i),(iii) grinding the cellulose containing material in a wet-milling process by means of the grinding balls (i.e. wet ball-milling) to a particle size as defined in claim 1 ,(iv) separating the grinding balls from the mixture of (iii).

7. The method of the preceding claim, further comprising an additional step(v) spray-drying the dispersion of cellulose particles after step (iv).

8. A dispersion comprising a composition of cellulose particles as defined in any of the preceding claims in water or an aqueous solution, said dispersion preferably comprising 40 to 99 wt.%, more preferred 50 to 98 wt.%, more preferred 60 to 97 wt.%, even more preferred 70 to 97 wt.% and most preferred 80 to 95 wt.% water or aqueous solution, referring to the total composition.

9. A dispersion according to the preceding claim, further comprising 0.5 to 25 wt.%, preferably 1 to 20 wt.%, more preferred 2 to 15 wt.% and even more preferred 3 to 10 wt.% of a plasticizer, referring to the total composition, wherein said plasticizer preferably is selected from glycerol, alkylene glycol mono alkyl ethers, polyalcohols, propylene glycols, ethoxylated or propoxylated ethylene or propylene, glycerol esters, glycerol triacetate, polyethylene glycols, methyl esters and amides and nonionic surfactants, wherein preferably the plasticizer is glycerol.

10. Method for preparing a cellulose film, a cellulose coating or cellulose capsules by using a composition of cellulose particles or a dispersion according to any of the preceding claims.11 . Method according to the preceding claim comprising the steps:a) preparing a homogeneous dispersion of cellulose particles having the features as defined in any of the preceding claims in water or an aqueous solution, wherein the cellulose particles are present in an amount of from 1 to 20 wt.% of the total weight of said dispersion, b) applying said dispersion onto a smooth / plane surface to prepare a film, or to the surface of a material for coating, in an amount that enables uniform distribution of the dispersion in the form of a closed layer on said surface, c) drying the dispersion to allow coalescence of the cellulose particles, wherein drying preferably is carried out to a water content in the range of 1 .5 to 12 wt.%.

12. Method for preparing a cellulose film according to claims 10 or 11 , further comprising d) drawing the resulting film from the smooth I plane surface.

13. Method according to any of the preceding claims 10 to 12, wherein at least one of the following is fulfilled:(I) in step (a) either a dispersion obtained in a method according to claim 6, step (iv) is used and optionally diluted, or a cellulose powder according to any of the preceding claims is dispersed in water or an aqueous solution,(II) in step (b) the dispersion is applied to the surface by casting or spraying and optionally evenly distributing,(III) in step (c) drying is carried out in a temperature range of from 10 to 80°C, preferably 20 to 60°C, more preferred 25 to 50°C, preferably by applying air, more preferred by blowing cool or tempered air.

14. A cellulose film, coating or capsule prepared from cellulose particles or a dispersion according to any of the preceding claims.

15. A cellulose film, coating or capsule according to the preceding claim, having a thickness in the range of from 10 to 300 pm, preferably 20 to 260 pm, more preferred 30 to 240 pm, even more preferred 40 to 200 pm, wherein preferably a cellulose film according to the preceding claims 25 or 26, having a thickness in the range of from 10 to 200pm, preferably 15 to 150 pm, more preferred 20 to 100 pm, even more preferred 30 to 80 pm or 40 to 60 pm, a cellulose coating according to the preceding claims 25 or 26, having a thickness in the range of from 20 to 300pm, preferably 40 to 270 pm, more preferred 60 to 250 pm, even more preferred 70 to 220 pm or 80 to 200 pm,a cellulose capsule according to the preceding claims 25 or 26, having a thickness in the range of from 30 to 300pm, preferably 50 to 200 pm, more preferred 60 to 180 pm, even more preferred 70 to 150 pm or 80 to 120 pm.

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