SE543850C2 - Method to produce a stable composition comprising hornificated nanocellulose particles, hornificated nanocellulose particle composition and its use - Google Patents

Abstract

The present invention relates to a method for producing a composition comprising hornificated particles of nanocellulose and/or microcrystalline cellulose, said method comprising the steps of: providing a suspension comprising nanocellulose and/or microcrystalline cellulose, drying said suspension so as to provide hornificated particles of nanocellulose and/or microcrystalline cellulose, adding a stabilizing agent in an amount of 0.1-50 wt-% based on the amount of particles, to the suspension after drying to form said composition. The invention also relates to a composition produced according to the method and a personal care composition.

Description

METHOD TO PRODUCE A STABLE COMPOSITION COIVIPRISING HORNI FICATED REAMOCELLULOSE PARTICLES FEGATED NANOCÉELLULGSE PARTlCLE GÜfflPOSlTlOhšAW? ETS USE TECHNI CAL Fl ELD The present disclosure relates to a method for producing a stable composition comprising ~- fièfwlïin »il il-»w\. 1.: ._.. utom . hornificated particles of nanocellulosem." :c ä' i rníc* BACKG ROU N D Plastic microbeads have been used for several years as exfoliation agents in personal careproducts, such as cosm etics, soaps, facial scrubs and toothpastes. However, such microbeadsare usually small (less than 1 mm), and when washed down the drain can pass unfilteredthrough sewage treatment plants, making their way into rivers and water canals, whichculminates in severe microplastic water pollution and endangerment of marine ecosystemsworldwide. The plastics from which the microbeads are formed are typically from fossil-fuel based sources, e.g. polyethylene, and are typically not biodegradable.

As a consequence, several countries have banned the use of plastic microbeads in personalcare products, and manufacturers are now seeking more environmentally-friendly alternatives.

Known alternatives to plastic microbeads used as for example abrasive components ofpersonal care products include organic materials such as ground fruit/nut kernels, cellulosegrains or wax beads (jojoba beads, synthetic wax, carnauba beads, candelilla beads), and inorganic materials such as silica or pumice stone.

However, such abrasive materials often have drawbacks. For instance, inorganic materialsare typically difficult to grind, are typically highly abrasive and are usually dense, makingthem difficult to maintain in suspension. Another drawback is that the yield during productionis quite low. Also, many fruit or nut kernels have a dark color, which can impact the color ofthe personal care product. Other abrasive materials are difficult to obtain in bulk or can present issues of toxicity or chemical intolerance when applied to the human body.

Various uses of cellulose fibers in skincare or cosmetic applications are provided in WO 2018/030392, WO2002/O22172, US2013330417, EP3081209 and JP2006240994A.

FR3017291A1 discloses cellulose exfoliant particles that disintegrate after application to human skin or scalp.

A drawback with the use of cellulose particles in the form of cellulose beads is that it could bedifficult to evenly disperse them in a composition since they might easily flocculate and/or sediment.

There is thus a need, for a new class of abrasive materials for use in personal care productswhich overcome some or all of the problems with known abrasive materials. First andforemost, the abrasive materials must be biodegradable. lmportantly, the abrasive materialsshould be skin-friendly (i.e. non-toxic). The abrasive materials should be easy to grind, andallow a range of abrasiveness (provided by both particle size and shape). The abrasivematerials should be stable during the lifetime of the product (both physically stable andchemically stable), should provide stable personal care products and be possible to evenlydisperse in a composition. Properties such as flavour, odour and colour should be as neutralas possible. Suitably, the abrasive materials should also have some porosity, which promotes uptake and release of chemical components.

SUMMARY The present technology relates to a method for producing a composition comprising hornificated particles of nanocellulose and! . mix of; ”Him cclšaåcs-, said method com prising the steps of: - providing a suspension comprising nanocellulose andfx mic; c. '.;*;.i*§.., c *lui sp, - drying said suspension so as to provide hornificated particles of nanocelluloseæz-ræefßfar - adding a stabilizing agent in an amount of 0.1-50 wt-°/> based on the amount ofparticles, to the suspension to the szusperïsåorï after -zšrvšno to f-:nrrn said c-:nznawosšiïitznvxfiïeazvefšn tina:- awaz'n::--z::elizsl~:>sc is rni-:zrcfšbaillatead cellulosa-ef ancï the hornifšcated parti-claes have a particle size of :nilåecf to a :xazrticle size of 1-2009 um p I: ' mdf: .' m2 i crysíaššin; c\:.l5ušc:::- and a stabilizing agent ige also provided.

A personal care composition is also provided, comprising the hornificated particles described herein and a stabilizing agent.

Further provided is the use of stabiiized hornificated particles comprising or consisting of . o *fšui so, _ m? f* å; microfibrillated cellulose (IVIFC), _ 'nifwry ~*'***ši': del* 'å " , as described herein, as an abrasive material in a home care or personal care composition.

Further aspects of the present technology are provided in the following text, figures and the dependent claims.

DETAI LED DI SCLOSURE lt is an object of the present disclosure to provide an improved method for the production of a stable composition comprising hornificated nanocellulose w *for :,:§;.,ioc~,,;i;.i*§.,c c *lfl ac particles. lt is known in the forestry and papermaking industries that harsh, extensive drying ordewatering of cellulose fibers or fibrils will cause them to hornificate. Hornification involvescoalescence or adhesion of fibers or fibrils to each other as a result of drying or dewatering,leading to lower porosity and poor solvent accessibility. Hornification can also be a propertychange on the surface of a fiber or fibril, e.g. that the surface becomes more hydrophobicwhich lead them to be more prone to flocculate. Cellulose fibrils aggregate strongly, and thusbecome virtually impossible to completely separate them again (also known as co-crystallization). Hornificated particles are thus coalesced fiber aggregates or microfibril orelementary fibrils. They are obtained by controlled drying of aggregation of nanofibrils intobeads or larger particles. Post-treatment (e.g. post-curing) can increase the extent of hornification.

Hornification is most often an undesirable feature. At the end of a fiber dewatering or dryingprocess the temperature of the material starts to increase, because there is no more water toevaporate. Hornification of fibers in e.g. a paper sheet generally leads to the strength properties of the paper sheet being reduced.

The present disclosure is based on the inventive realization that it is possible to produce amore stable composition, including both a more stable intermediate composition according tothe invention and a more stable final composition, such as a personal care or homecare product, paint or other final com position, com prising hornificatedfigjgrgílb;iii§t§§__ç_e_l§uj_o_sg, vh-w H-li i i . -c i, ”nu o; . .L r o. *t' iii. e ;;.i*uš-ise particles by addition of a stabilizing agent already after the formation of the hornificated particles, and the production of thecomposition according to the invention. The composition according to the invention is anintermediate composition to be mixed with additional additives, chemicals or compositions toform the final end product or final composition. The composition can be in either wet or drystate. Normally stabilizing agents would be added later during the formation of the finalcomposition to be used. lt was now found that by adding the stabilizing agent already directlyafter the formation of the particles, a more dispersible composition is obtained, and it can beused to produce a more stable final composition. Also, it has been found that it will be easierto evenly disperse the composition, or the hornificated particles in the composition, in thefinal product. Also, it would be possible to provide a composition that would comprise the optimum amount of stabilizing agent for that amount and type of hornificated rnicrofibršllaïed calëušose .cšlzfl a: :n Lier :..L^.. gpñtuišlnc , .ilulorc particles present in the composition,which facilitates the mixing of the composition with other ingredients in order to produce thefinal product, e.g. a coating, a personal care or home care product or a paint. The stabilizingagent can be added and mixed with hornificated particles that are still in wet form or with dried hornificated particles.

The present disclosure relates to a method for producing a com position comprising hornificated particles of n .czâš :iof , izrå' . ,:., .:'f,.°talâi..z .cli ficrzmicrofëbršllafed said method comprising the steps of: providing a suspension comprising H--L .-v->-" fšv... ßHus. mmm/vs hen/zum. t.. tiil., .:.:,Elul.:^ rnšcrofibriišated c-:aiEuE<::-se, drying the suspension ~~ .- t- . .lir.ui\.~«.« so as to provide hornificated particles of said ' :mšczrofiânršlšatecš cellulose, adding a stabilizing agent in an amount of 0.1-50 wt-°/> based on the amount of particles, to the suspension after drying to form saidcomposition. The amount of stabilizing agent is preferably between 1-30 wt-°/>, preferablybetween 5-25wt-% based on the total amount of particles. The amount of stabilizing agentmay depend on the type of stabilizing agent used as well as on the amount and kind ofparticles used in the composition. lf more than one stabilizing agent is used, the amount of stabilizing agent mentioned is the total amount of the different stabilizing agents.

With a more stable composition is meant a composition that has improved colloidal stability,and which is less prone to sedimentation and inter-particle flocculation. The composition canbe left for at least one week and no sedimentation occurs. The composition also hasimproved stability at higher electrolyte concentrations, such as mono-, di- or multivalentions, at a broader temperature interval and is more stable during transportation, i.e. it ismore resistant against vibration motions and temperature fluctuations, which occur during transportation.

Hornification is a result of harsh drying or dewatering conditions, which is achieved by thedrying step according to the present invention. With drying is also meant dewatering. Thedrying step provides hornificated particles, which preferably have a dryness level of 70% ormore, and preferably 80% or more, more preferably 90% or more, most preferably 95% ormore. The drying step suitably takes place for a time of 1-1800 seconds, 10-1000 preferably15-500 seconds, and more preferably 30-120 seconds. The drying step may - depending onthe drying method -take place at a temperature of 70-350°C, preferably 80-185 °C, andmore preferably 100-150 °C.

The drying step preferably takes place in an inert atmosphere. Drying in an inert atmospherereduces the formation of oxidised material with an off-white color, thereby maintaining thebrightness of the hornificated particles closest to white. The nanocellulose iii... iiulosc could also be dispersed in a co-solvent such as an alcohol solvent prior to drying.

The drying step is preferably done by thermal, radiation and/or mechanical drying. Thedrying step preferably comprises spray drying, ring drying, flash drying, TurboFšotor mill drying, oven drying, or a combination thereof, preferably flash drying or spray drying.

The extent of hornification may also be characterized by the water absorption capacity of theparticles, defined as g water uptake/g material. Water absorption capacity can be determinedby EDANA method NWSP 240.0.Fš2, in which saline solution is replaced by deionized water.Hornificated particles may therefore have a water absorption capacity of less than 10 gwater/g material; preferably less than 5 g water/g material; more preferably 1 - 5 g water/gmaterial. The water absorption capacity of the com position may be more than 10g water/gmaterial, preferably more than 15 g water/g material and most preferably more than 20 g water/ g material.

The degree of hornification may also be characterized by the amount of fibrils released by theparticles upon wetting. For the hornificated particles according to the present invention thepercentage of loose fibrils upon wetting is <5%. Dispersibility in aqueous media can bedetermined via e.g. Canadian standard CAN/CSA-Z5100-17 5.3.10.

The hornificated particles that comprises or consists of . '. o mišu* so, _ .ef r' f å; *Jr Friso: *rconeiei-s--ofi---microfibrillated cellulose (MFC), preferably unmodified native microfibrillated cellulose (MFC). The MFC particles may comprise at least 20 wt% MFC, preferably at least 30wt% MFC, more preferably at least 50 wt% MFC, even more preferably at least 70 wt% l\/lFC, vn ~ l f- ~ h 'fit $ ' ~ »- L il”: vi J' l - ~.k-(IL) lwv \I(J( L~)\.~\4' .u '|.|r,-\|\,) I -uxJíluålx-L l|.| Or Wto/O TEA, :i ful-it: utuug. i fïx Ti - 5 'l» i-l + ~'*:i >\,\..,...4. in; ...u :v44 »C i' 'Rfl 'x1""'f“ w- " i vw , vw.fwmui om n: u). i 1 t i + , -ñ/ 7150:*-:u .v. Hcanuviu rsufiy .wa :mp-r uL :v44 ca av; .tv-ww, “MV hllfi* ~ l»- $ v-f-L-J, f-š-l f- p F' lt ' lUl f*WL liv ,ili :cpu i x ut; i..- Qs. uvvL.~0 ii v Typically, the particles solely com prise cellulosic fibres. The particles m vw i .fwx i l , . 5 'l» a- + ”r ,,...v :nu icvuma. an; u» :C44 :c vv.. may however- apart from the micrifbršllaited celluâos- nfn šlulozc "ndpr r ,._,:t.tâiš..c - additionally comprise cellulosic fibres such as e.g. pulp fibers or chemically modified nanocellulose. lt has been found that when microfibrillated cellulose is dried at harsh conditions to a dryness|eve| above 61%, hornificated microfibrillated cellulose particles are formed. Suitably, thehornificated particles have a dryness |eve| of 70% or more, and preferably 80% or more,more preferably 90% or more, most preferably 95% or more. Dryness |eve| can bedetermined by an oven-drying method, e.g. ISO/CD 638-1 “Paper, board and pu/ps - Determination of dry matter content".

The MFC of the composition to form the hornificated particles may be unmodified MFC (nativeMFC) or chemically modified MFC, or a mixture thereof. ln some embodiments, the MFC is anunmodified MFC. Unmodified MFC refers to MFC made of unmodified or native cellulose fibers.The unmodified MFC may be a single type of MFC, or it can comprise a mixture of two ormore types of MFC, differing e.g. in the choice of cellulose raw material or manufacturingmethod. Chemically modified MFC refers to MFC made of cellulose fibers that have undergonechemical modification before, during or after fibrillation. ln some embodiments, the MFC is achemically modified MFC. The chemically modified MFC may be a single type of chemicallymodified MFC, or it can comprise a mixture of two or more types of chemically modified MFC,differing e.g. in the type of chemical modification, the choice of cellulose raw material or themanufacturing method. The modified MFC may be carboxymethylated cellulose, preferablywith a degree of substitution (DS) less than 0.4, more preferably with a DS between 0.05- 0.35.

By nanocellulose is meant any one of microfibrillated cellulose (MFC), bacterial cellulose and/or nanocrystalline cellulose.

Microfibrillated cellulose (MFC) shall in the context of the patent application be understood tomean a nano scale cellulose particle fiber or fibril with an average diameter of less than 1000nm. MFC comprises partly or totally fibrillated cellulose or lignocellulose fibers. The liberatedfibrils have an average diameter less than 1000 nm, whereas the actual fibril diameter orparticle size distribution and/or aspect ratio (length/width) depends on the source and the manufacturing methods.

Depending on the source and the manufacturing process, the length of the fibrils can vary from around 1 to more than 100 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). ln some embodiments, the MFC comprises less than 50 wt°/>, preferably less than 30 wt°/>, and more preferably less than 20 wt°/>, of MFC fibers having a diameter above 1000 nm.

There are different synonyms for MFC such as cellulose microfibrils, fibrillated cellulose,nanofibrillated cellulose, fibril aggregates, nanoscale cellulose fibrils, cellulose nanofibers,cellulose nanofibrils, cellulose microfibers, cellulose fibrils, microfibrillar cellulose, microfibrilaggregates and cellulose microfibril aggregates. The cellulose fiber is preferably fibrillated tosuch an extent that the final specific surface area of the formed MFC is from about 1 to about400 m2/g, or more preferably 50-300 m2/g when determined for a solvent exchanged and freeze-dried material with the Nitrogen sorption (BET) method.

Various methods exist to make MFC, such as single or multiple pass refining, pre-hydrolysisfollowed by refining or high shear disintegration or liberation of fibrils. One or several pre-treatment steps are usually required in order to make MFC manufacturing both energyefficient and sustainable. The cellulose fibers of the pulp to be utilized may thus be pre-treated, for example enzymatically or chemically, to hydrolyse or swell the fibers or to reducethe quantity of hemicellulose or lignin. The cellulose fibers may be chemically modified beforefibrillation, such that the cellulose molecules contain other (or more) functional groups thanfound in the native cellulose. Such groups include, among others, carboxymethyl (CMC),aldehyde and/or carboxyl groups (cellulose obtained by N-oxyl mediated oxidation, forexample "TEMPO"), or quaternary ammonium (cationic cellulose). After being modified oroxidized in one of the above-described methods, it is easier to disintegrate the fibers intoMFC or nanofibrils.

The nanofibrillar cellulose may contain some hemicelluloses, the amount of which isdependent on the plant source. Mechanical disintegration of the pre-treated fibers, e.g.hydrolysed, pre-swelled, or oxidized cellulose raw material is carried out with suitableequipment such as a refiner, grinder, homogenizer, colloider, friction grinder, ultrasoundsonicator, fluidizer such as microfluidizer, macrofluidizer or fluidizer-type homogenizer.Depending on the MFC manufacturing method, the product might also contain fines, ornanocrystalline cellulose, or other chemicals present in wood fibers or in papermakingprocess. The product might also contain various amounts of micron size fiber particles that have not been efficiently fibrillated.

MFC is produced from wood cellulose fibers, both from hardwood or softwood fibers. lt can also be made from microbial sources, agricultural fibers such as wheat straw pulp, bamboo, bagasse, or other non-wood fiber sources. lt is preferably made from pulp including pulpfrom virgin fiber, e.g. mechanical, chemical and/or thermomechanical pulps. lt can also be made from broke or recycled paper.

Hemicellulose content of the MFC fibers is typically 1-25%, while it is not limited by thesevalues. MFC crystallinity is preferably 35-85% and more pref. 45-75%. Various grades ofMFC, including those already commercially available and currently on the market, can be used as starting material for the preparation of the dry MFC particles of the invention. 1,- vi: UUH-L- w: -~ »AW i"s.- 1 'lst ~' Ih:'l(\"“^ L~ ~» "si » v-.s- 'ífi 4 »-. isflll » »v sl -~vv. s i Hos i)_, Ci.s so .s s u o \_ f j ._ ui i ioo-.i ivu, _ uiiiui.) io' .ys s ii ou. uscfuu v- v-H-v-s ' ' s i-~- i's.- ~ -s-' J? .v- »h . »-. i! TL» b'l(\:"'^ » lf. v-.s-.' .~ll-. ,-. . l i» i.i; oio s oo- ufy ssvuss sä uni-o.. soo c- i i u-i u. . i 1 f _ o io _- ~.-~.i iu_¿ ui ) \- wii.w êl-s ' l-- - sil L» ' i- ~' ~ flï il i i F w- ~ \' - 'w-l l>~ f-sl» i- f“' - f-s vl- vi Ml-i >4 '\"°"*f“ i >i ii u, 13. iu_¿ .yo-_ i_¿ _ s vis y i v _ i iv i iiuuii i _ 1.1 _ iQ. o _, o. i .v. _,i f-s wa i i f-.IV- slw' i Fill: ~ ê~ v +P» - ß fl- v» å? i' fUl 7"' fUl'“^f\ w' -sf-ll l-s- _ . II, w a . -f-s a'.c- Q. io _,«os iuii i s«os. i s i i s s s say Ci i i . i i f .yi .v i_ i u Ci u. si u-.v- ui u äeragt-äa--fiieove--ê-iirsi-v The stabilizing agent is preferably nanocellulose and/or a dispersant. The molecular weight ofthe dispersant is preferably above 5000 g/mol, preferably above 10000 g/mol, preferablyabove 50000 g/mol, preferably above 100000 g/mol. lt is important not to use a dispersantwith too low molecular weight since it will then not be possible to achieve the stabilizingproperties of the composition. The nanocellulose may be unmodified MFC or a chemicallymodified MFC, preferably an anionic MFC. lt may be preferred to use phosphorylatednanocellulose or carboxymethylated nanocellulose as a stabilizing agent. The dispersant ispreferably an anionic dispersant, preferably carboxymethylated cellulose, anionic starchand/or anionic polyacrylamide. The stabilizing agent may also be a saccharide, such as amonosaccharide, e.g. glucose, mannose or galactose, oligosaccharides such as sucrose orlactose or polysaccharides or other water-soluble polym er, such as cellulose derivate orhydrophilic polymers such as polyethylene glycol (PEG) or polyvinyl alcohol (PVOH). lt maybe preferred to use a mixture of different stabilizing agent. One preferred combination is touse a mixture of nanocellulose, preferably microfibrillated cellulose and carboxymethylatedcellulose (CMC) with a high molecular weight. The composition may then preferably comprise1-30wt-°/> of nanocellulose and 1-30wt-°/> of CMC. The ration between CMC and MFC ispreferably 1:100 to 100:1. lf native nanocellulose is added as a stabilizing agent it might bepreferred to also add another stabilizing agent, such as CMC, which will both act as astabilizing agent but also prevent the nanocellulose added from coalescence (hornificate)during eventual final-drying steps. lt is preferred not to cause the nanocellulose added as a stabilizing agent to hornificate during future drying steps. lt may be preferred to use the same kind of nanocellulose for the production of the hornificated particles and as the stabilizing agent, preferably native nanocellulose or carboxymethylated nanocellulose is used. lt might be preferred to use microfibrillated cellulose (MFC), preferably native MFC or carboxymethylated MFC.

The com position according to the invention preferably comprises 0.1-20 wt-°/>, preferably 0.5-10 wt% of hornificated particles.

The degree of abrasiveness of the particles may be related to the particle size and shape,with larger and more angular particles generally providing a more abrasive feel. Dependingon the end product, smaller or bigger particles are desirable. Therefore, hornificated particlesaccording to the present technology, an average dry particle size (D90) of 1-2000 pm, preferably 50-1000 pm, and more preferably 150-750 pm. Particle size may bemeasured by laser diffraction (as per ISO/DIS 13320) or by SEI\/I imaging combined withparticle analysis (as per ISO 13322-1:2014), preferably laser diffraction.

The cellulosic nature of the han ^ *ful ::. 1:* rniïzf: .y taiïir: “rnicmfišïzršliatecš -celitzšosc particles provides a certain level of porosity, e.g. a porosity in the range 0-25°/>, preferably inthe range 5-15%. Porosity can be determined by mercury porosimetry and gas adsorption asper ISO 15901-1:2016. This is useful when the particles are used in personal care com positions, as it im proves uptake of other components of the composition, and the particle's overall compatibility and dispersibility within the com position.

The degree of abrasiveness may be related to the particle hardness. Hornificated particlessuitably have a hardness in the range 60-80 Shore D. The abrasiveness of exfoliants dependson their size and shape. The smallest particles are usually used in facial scrubs, whereas themedium-sized particles are used in body scrubs and finally the biggest particles in foot scrubs.

Another parameter of interest is the surface area. Suitably, the surface area of thenanocellulose particles should be >1 m2/g, suitably between 1-1000 m2/g. Calculating the specific surface area of solids can be carried out by the BET method (e.g. using ISO 9277).

The hornificated particles have a particle size - or are milled to a particle size - of1-2000 pm, preferably 50-1000 pm, and more preferably150-750 pm.

The method may further comprise addition of wetting agents before, simultaneously or afteraddition of the stabilizing agent. The wetting agent is added before eventual final drying ofthe composition. The amount of wetting agent in the composition is preferably between 0.1-5wt-°/> based on the amount of particles, preferably between 0.5-2 wt%. The wetting agent is preferably surface-active chemicals with a hydrophilic-lipophilic balance (HLB) of 1-12, |2o preferably between 2-10 and more preferably between 3-9. The wetting agent can be ananionic, zwitter-ionic, non-ionic or cationic surfactant. The wetting agent is added in order todecrease the hydrophobicity of the particles and to make the com position easier to mix with an aqueous solution in order to produce aqueous products.

The method according to any the preceding claims, further comprises mi||ing and/or sieving said hornificated particles either before or after addition of the stabilizing agent.

The method may include a step of actively coo|ing the hornificated particles after the drying step. This is done to prevent the particles from f|occu|ating too much.

The method may further include a step of drying the composition to a dryness level above80% after addition of the stabilizing agent, i.e. a final drying step. This is done to provide adry or almost dry composition that can be sold and easily transported to customer siteswhere re-dispersion of the composition with additional additives, chemicals, suspensions orcompositions is done in order to produce the final composition. This final drying step may bedone by any known drying method, preferably by thermal, radiation and/or mechanicaldrying e.g. spray drying, ring drying, flash drying, TurboFšotor mill drying, oven drying, or a combination thereof.

The present disclosure further relates to a composition com prising hornificated particles of ::::: Eicš: ^ frzfi/ i JJ ::::'_ t. ïåir* rnšcrofiïorilšated cellulose and a stabilizing agent. Thestabilizing agent is preferably nanocellulose and/or a dispersant with a molecular weightabove 5000g/mol. The hornificated particles of the composition has an averagedry particle size (D90) of 1-2000 um, preferably 50-1000 um, and more preferably 150-750um, most preferably 400-750 um.

The present disclosure also relates to a composition produced according to the method mentioned herein.

The present disclosure also relates to a personal care com position com prising thecomposition described herein. The personal care composition may be in the form of a liquid,wherein the hornificated particles are dispersed in said liquid or in the form of a solid,wherein the hornificated particles are dispersed throughout said solid. The definition "liquid"includes semi-liquids such as gels or creams. The personal care com position preferablycomprises 0.1-20 wt °/>, preferably 0.5-10 wt °/> of said hornificated particles. The personalcare com position may also com prise one of more surfactants, or other typical additives inpersonal care products including rheology modifiers, humectants, pigments, etc. Examples of suitable personal care products are toothpastes, face scrubs, body scrubs, foot scrubs, and 11 bath and shower products. As a final step, the method may include a step of formulating thehornificated particles into a personal care composition. Exfoliants are typically added into personal care products during the last formulation step under low shear. ln a further embodiment, the use of hornificated particles comprising or consisting of »w \'ll-ïsus v Java se andff mic." c.ynfaifir:Jnšcroíibršlšatecš cellš-ulose, described herein as anabrasive material in a personal care composition is provided. Other uses include apapermaking composition, a paint composition, a homecare product, pharmaceuticals or afood product. All details of the particles described above are also relevant for these uses, mutatis mutandis.

The particles according to the present invention are bio-based and biodegradable, andpossess light color (white to yellowish). They are also tuneable in terms of their size, shapeand hardness/abrasiveness, depending on the drying technology used, temperature of drying(drying rate), grade and initial solids content. The particles are also non-toxic and can be readily produced (upcycled) from by-products of the papermaking and forestry industries.

The particles may com prise one or more additives, which are incorporated within thehornificated particles. Suitable additives include surfactants, solvents, oils, proteins, vitamins, pharmaceuticals, pigments etc. ln particular, the particles may comprise one or more pigments, which could be incorporatedinto the particles prior to drying, during the drying process or post-drying. As the particlesthemselves do not have a strong color, the color of any pigment will be “true”, i.e. not significantly affected by any color of the particles themselves.

Although the invention has been described with reference to a number of aspects, examplesand embodiments, these aspects, examples and embodiments may be combined by the person skilled in the art, while remaining within the scope of the present invention.

Claims (22)

12 CLAI l\/IS

1. A method for producing a composition comprising hornificated particles of nanocellulose, said method comprising the steps of: - providing a suspension comprising nanocellulose, - drying the suspension so as to provide hornificated particles of said nanocellulose,charact-:sfziz-:aæ-:l in - adding a stabilizing agent in an amount of 0.1-50 wt-% based on the amount ofparticles, to the suspension after drying to form said composition wherein thenanoce||u|ose is microfibrillated ce||u|ose and the hornificated particles have a particle size - or are mi||ed to a particle size - of 1-2000 um.

2. The method according to c|aim 1, wherein said stabilizing agent is nanoce||u|ose and/or dispersant having a mo|ecu|ar weight above 5000 g/mo|.

3. The method according to c|aim 2 wherein the dispersant is an anionic dispersant which is carboxymethyiated ce||u|ose, anionic starch and/or anionic polyacrylamide.

4. The method according to any of the preceding c|aims wherein the composition comprises preferably 0.1-20 wt% of hornificated particles.

5. The method according to c|aim 1 wherein the drying step takes place to providehornificated MFC particles having a dryness level above 61%, preferably of 70% or more, and preferably 80% or more, more preferably 90% or more, most preferably 95% or more.

6. The method according to any one of the preceding c|aims wherein said drying stepcomprises spray drying, ring drying, flash drying, TurboFšotor mi|| drying, oven drying, or a combination thereof, preferably flash drying or spray drying.

7. The method according to any of the preceding c|aims, wherein the hornificatedparticles have a particle size - or are mi||ed to a particle size - of 50-1000 um, and more preferably 150-750 um.

8. The method according to any of the preceding c|aims, further comprises addition of wetting agents before, sim ultaneously or after addition of the stabilizing agent. 13

9. The method according to any the preceding c|aims, further comprises milling and/or sieving said hornificated particles either before or after addition of the stabilizing agent.

10. The method according to any of the preceding c|aims, further comprising a step of actively cooling the suspension comprising hornificated particles after the drying step.

11. The method according to any of the preceding c|aims, further comprises drying the composition to a dryness level above 80% after addition of the stabilizing agent.

12. A composition comprising hornificated particles of nanoce||u|ose and a stabilizingagent wherein the nanoce||u|ose is microfibrillated ce||u|ose and the hornificated particles having an average dry particle size (D90) of 1-2000 um.

13. The composition according to c|aim 12 wherein the stabilizing agent is nanoce||u|ose and/or a dispersant with a mo|ecu|ar weight above 5000g/mol.

14. The composition according to any of the claims12-13,wherein the hornificatedparticles having an average dry particle size (D90) of 50-1000 um, and more preferably 150-750 um, most preferably 400-750 um.

15. A personal care composition comprising the composition according to any one of the claims12-14.

16. The personal care composition according to c|aim 15, in the form of a liquid, wherein the hornificated particles are dispersed in said liquid.

17. The personal care composition according to c|aim 15, in the form of a solid, wherein the hornificated particles are dispersed throughout said solid.

18. The personal care composition according to any one of c|aims 15-16, comprising 0.1- 10 wt °/>, preferably 0.5-5 wt °/> of said hornificated nanoce||u|ose particles.

19. The personal care composition according to any one of c|aims 15-18, comprising one of m ore surfactants.

20. The personal care composition according to any one of c|aims 15-19, being selected from toothpastes, face scrubs, body scrubs, foot scrubs, and bath and shower products. 14

21. A use of the composition, according to any one of ciaims 12-14 as an abrasive material in a personal care com position.

22. A use of the composition, according to any one of ciaims 12-14 in a papermaking com position, a paint com position, a homecare product, pharmaceuticais or a food product.