Description

The present invention relates to dispersions of cellulose acetate.

The invention further relates to a process to produce cellulose acetate dispersions, the process comprising steps of adding certain solvent mixture, a feed mixture and optionally a further solvent feed, the feed mixture comprising dissolved cellulose acetate (CA), such mixtures and feeds being added to a mixing zone at certain ratios and contents such that the overall ratio of the various solvents are maintained at a specific ratio throughout the additions and mixing, de-agglomerating the CA-dispersion obtained, removing at least partially organic solvent employed in the previous steps, optionally adding additives and/or stabilizer, optionally further reducing the amounts of organic solvent(s) present, optionally further imparting shear energy to obtain smaller particle sizes and preferably a narrower particle size distribution of the dispersed CA within the CA- dispersion, and optionally drying the CA-dispersion to a fine-particulate CA-powder.

The invention further relates to cellulose acetate-dispersions obtainable by such process.

The invention also relates to the use of such cellulose acetate-dispersions as opacifiers in formulations or compositions within the field of application of fabric and home care, industrial and institutional cleaning, cosmetics, personal care, lacquer and colorants formulations, agricultural active formulations.

Cellulose acetate dispersions are known as such, including their production processes:

Common procedures are the dissolution of cellulose or its derivatives, the formation of a spherical droplets from the solution, the stabilization of the droplets, the phase inversion of the droplets and at least a washing.

The first beads were produced by extrusion method; later the dispersion method became more important. The raw materials are usually cellulose, cellulose xanthate (i.e. viscose) or cellulose acetate.

In patent EP0265924 a method is specified for preparing uniform polymer particles which have a volume average particle size of 10 to 1000 mm amongst others made from cellulose acetate with different degrees of acetylation.

EP0750007 discloses processes of making cellulose beads of an average particle size of the cellulose beads ranging from 1 to 20 millimeter, using a solution of cellulose acetate being free from halogenated hydrocarbons.

In Macromolecular Symposia 2008, 262, 89-96 by Fischer et al. (“FISCHER”) the production processes of EP 0750007 were followed to form cellulose acetate beads; the cellulose acetates were first examined in terms of solubility, turbidity and degree of substitution, molecular mass and distribution of substituents along the polymeric chain, then cellulose beads were synthesized using an emulsion process, and the beads were analysed regarding particle size, porosity and morphology; finally the relationship between the cellulose acetate-characteristics and the properties of the beads were investigated. The solvent used as reaction medium for coagulation was ethyl acetate-methanol in a ratio of 100:17.5. However, the method employed, and the solvent used is not suitable for large scale production, in that both ethyl acetate and methanol are not preferred solvents for many applications. Also, the use of two organic solvents should preferably be avoided, as such solvent mixtures are difficult if not impossible to cost-efficiently separate especially when contacted with water as disclosed in EP0750007 and further exemplified by FISCHER.

Also, the particle sizes as disclosed by FISCHER are in most cases too broad for the use as opacifiers.

The use of such cellulose acetate-beads as opacifier is not disclosed in any of the aforementioned documents.

Hence, there was still a need for a process suitable for large-scale production of cellulose acetate- dispersions having a small particle size of below 20 micrometer and smaller and with a narrow particle size distribution, and preferably with no particle sizes larger than 190 micrometer, more preferably 125 micrometer present, which are easy to prepare, stable upon storage without coagulation nor sedimentation or at least can be easily re-dispersed evenly with simple stirring or upon pumping from a receptable to another receptable.

There was especially the need for a cellulose acetate dispersion exhibiting excellent optical properties which exhibits good opacifying properties, i.e. that scatter visible light evenly without any dispersed particle being detectable for the human eye.

Moreover, the was the need to provide cellulose acetate-dispersions of the afore-mentioned properties having also a low viscosity, which makes such dispersions suitable for large-scale commercial logistics and transport, such as pumping, dosing, storing and the like using standard equipment without the need for special high-viscosity-handling measures.

Cellulose acetate („CA“) can stem from various source, such as cotton linters (i.e. from cotton source) or wood pulp (i.e. from the processing of wood, which can be for the production of paper). In view of economical reason it is favorable to use wood sources, as wood is more abundant in the world and thus CA from wood is cheaper than from cotton.

CA can be characterized by its amount of hemi-cellulose. Hemi-cellulose can be characterized by its content of xylose and mannose, both of which can be detected using suitable analytical methods. The amounts in cotton are lower (usually less than 0.1 % hemi-cellulose) than in wood (usually about 1 %, which is made up on average by about 0.8% xylose and about 0.2 % of mannose). Upon the processing of wood to obtain wood pulp, the amounts of hemi-cellulose increase drastically to about up to 25 wt.%.

Hemi-cellulose ’s solubility in organic solvents is much lower, and thus the solubility of CA (i.e. the solubility of hemi-cellulose) in suitable solvents such as acetone is weaker with increasing hemicellulose-content. This can lead to turbidity of such CA-solutions in acetone with increasing amounts of hemi-cellulose in CA.

The content of hemi-cellulose is usually analyzed by HPLC-methods. A certain amount of hemicellulose leads to incomplete dissolution of CA and thus turbidity in such CA-“solutions” in acetone.

The degree of substitution (“DS”)-number (which is given without units). The DS relates to the degree of substitution with acetate-g roups. A DS of below 2.2 indicates typically that such CA is not soluble in acetone anymore. It is also known that CA contains certain amounts of salts, which stem from the process of obtaining CA. In “technical grade CA” the salt-contents are usually in total below about 500 ppm, which is made up by usually up to about 200 ppm sulphate and usually below about 100 ppm acetate. As counter-ions typically magnesium and calcium are present. Such Mg- and Ca-salts support the stabilization of CA against auto-hydrolysis, but on the other hand also are the cause for „crosslinking“ via ions (ionogenic crosslinking) and thus lead to different viscosity profiles of CA’s of the same molecular weight although having the same molecular weight of CA. Autohydrolysis usually is a slow process involving the formation of acetic acid, and thus is an important factor for storage stability, as e.g. the amount of acetic acid can increase from about 200 ppm to over 1000 ppm during storage for 5 years. Nevertheless, it is advisable to remove acetic acid and hemi-cellulose, which can be accomplished relatively easily by heating of CA dispersed in water, preferably at about the boiling temperature of water, and subsequent washing with water and drying.

A further cause for coagulation and super-aggregation in dispersion but also in solutions of CA is -besides the actions of salts as described above - the property of CA to form complexes via hydrogen-bridging bonds which thus also “crosslink” the CA and hence increase the viscosity as well.

As a result, the molecular weight of CA, the DS-value, the distribution of the acetate-groups in the main-chain of the CA and the amount of hemi-cellulose are the deciding factors during the particle formation upon production of CA-dispersions from CA-solutions: the morphology and the particle sizes of the resulting secondary dispersions of CA are defined by these factors.

To avoid coagulation upon the solids formation it is advisable to remove super-aggregates before subjecting to the dispersion-forming process. This can be accomplished by filtering a CA-acetone- solution via suitable filters having pore sizes of about 5 micrometres.

The object is achieved by a process to produce a cellulose acetate dispersion comprising especially the following embodiments, but not limited to those specific embodiments.

Embodiment 1

Process to produce a cellulose acetate-dispersion (“CA-dispersion”) comprising the steps of a) providing a feed mixture comprising cellulose acetate (“CA”), the CA being selected from celluloses i) having a hemi-cellulose-content, the hemi-cellulose-content which is characterized by the sum of xylose and mannose content therein, of less than 5 weight percent based on the total weight of cellulose acetate, and ii) a molecular weight of less than 200.000 g/mol Mw but not less than 10.000 g/mol, and iii) a polydispersity index of less than 5, the CA being dissolved in a mixture of solvents comprising aa) at least one water-miscible aprotic organic solvent being a solvent for cellulose acetate (“solvent 1 ”) preferably a ketone and/or an organic carbonate, more preferably a ketone, even more preferably acetone, and most preferred acetone as sole solvent 1 , and bb) at least one further solvent that is a non-solvent for cellulose acetate such solvent being miscible with the at least one water-miscible aprotic organic solvent (“solvent 2”), preferably water, alcohol(s) and/or alkoxylated alcohols, more preferably water, with the solvent 1 and the solvent 2 having a certain ratio to each other, said ratio of solvent 1 to solvent 2 preferably being from about 1 :0,5 to about 1 :3, preferably 1 :1 to 1 :2, more preferably 1 :1 ,05 to 1 :1 ,4, most preferably about 1 :1 ,2, with the solvent 1 preferably having a boiling point which is lower than the boiling point of the solvent 2, and cc) optionally one or more stabilizers and/or additive(s), helping to stabilize the CA- dispersion and/or avoiding coagulation of the CA-dispersion within the following remaining steps of the present process and preferably also within the CA-dispersion upon transportation and storage, preferably adding a non-ionic surfactant of low HLB- value of at most 10, preferably at most 8, more preferably at most 5 and most preferably at most 3, and preferably adding an amphiphilic additive; b) providing a solvent mixture containing at least one solvent 2, preferably water, and optionally a further organic solvent, the latter which can be solvent 1 and/or a solvent different to those mentioned before in this present step, preferably being solvent 1 , the ratio of solvent 1 to solvent 2 in the solvent mixture prior to the addition of the feed mixture being from 2:1 to 1 :2, preferably from 1 ,7:1 to 1 :1 ,7, more preferably from 1 ,5:1 to 1 :1 ,5, most preferably from 1 :1 ,1 to 1 :1 ,4; c) adding said solvent mixture of step b) to said mixing zone; d) adding said feed mixture of step a) to a mixing zone, e) optionally adding further feed consisting of solvent 2, and preferably consisting essentially of water, most preferably being only water, to said mixing zone, wherein the addition of the solvent mixture in step c) and the addition of the feed mixture in step d) and the optional further feed of solvent 2 of step e) to said mixing zone are each independently from each other performed either as a batch-wise or semi-continuous or continuous addition, and wherein the addition is performed either in parallel, after each other or with at least partial timely overlap of the additions, preferably with the addition of the solvent mixture starting prior to the addition of the feed mixture and the further feed of step e), so as to maintain throughout the additions and until the end of the mixing in said mixing zone a certain ratio of solvent 1 to solvent 2 from about 2:1 to about 1 :3, more preferably from about 1 ,5:1 to 1 :2, , even more preferably 1 :1 ,05 to 1 :1 ,4, and most preferably about 1 :1 ,2, f) mixing the mixture in said mixing zone for a certain period of time, preferably for 1 minute to 3 hours, at a certain temperature, preferably at a temperature from 10 to 50 °C, preferably from 15 to 40 °C, more preferably 20 to 30 °C, to provide the initial CA-dispersion, g) de-agglomeration of the initial CA-dispersion using external forces and/or by oxidation, h) removing at least part of the organic solvent(s), preferably at least solvent 1 , and optionally also partial amounts of the solvent 2, from the CA-dispersion to obtain a concentrated CA- dispersion, the weight-percentage of such concentrated CA-dispersion being preferably at least 3 wt.%, and at most preferably 20 wt.%, more preferably about 5 to 15 wt.%, most preferably about 10 to 15 wt.%, such as 11 , 12, 13 or 14, i) optionally adding at least one further, preferably amphiphilic, additive, preferably a stabilizer; j) optionally subjecting the concentrated CA-dispersion to a step of further removing organic solvent, preferably solvent 1 and - if solvent 2 also comprises an organic solvent preferably also said organic solvent from solvent 2 - , to reduce the residual organic solvent content to below 1 weight percent, preferably below 0,5, even more preferably below 0,1 and most preferably below 0,05 weight percent, each based on the dispersion, to obtain a purified CA- concentration; k) optionally subjecting the CA-dispersion resulting from a previous step to a means imparting a certain amount of shear energy which is sufficient to reduce the particle size of the CA- particles within the dispersion, preferably ultrasound-generators and/or mechanical homogenizers, and more preferably in combination with the exertion of increased pressure, most preferably using a high-pressure homogenizers, most preferably such as stirrer-type devices, such as dispersion disk, disc-type stirrers and oblique blades, which are known by e.g. company Netzsch, e.g. the Mastermix Dissolver, and company RVT-Systeme e.g. the disc-type stirrers or oblique-blade stirrers, l) optionally adding at least one further additive, preferably an amphiphilic stabilizer, and m) optionally drying the CA-dispersion obtained from a previous step to a fine powder containing the CA as finely dispersed powder, with the proviso that no particles are formed during this process and remaining at the end of this process that are removable with a 125 micrometer-filter.

Embodiment 2

Process according to Embodiment 1 wherein the CA employed has a hemi-cellulose-content, said hemi-cellulose content which is characterized by the sum of xylose and mannose content therein, in between 0 and 3, preferably up to 2, more preferably up to 1 ,5 weight percent based on the total weight of CA.

Embodiment 3

Process according to Embodiment 1 or 2, wherein the CA employed has i. a molecular weight Mw of from 10.000 to 150.000 g/mol, preferably 20.000 to 120.000, preferably 40.000 to 110.000 g/mol, and ii. a polydispersity of from 1 ,5 to 5, preferably 2 to 4, and at most 3,5, and

Hi. a DS of more than 1 and up to 4, preferably 1 ,5 to 3, more preferably about 2 to 2,8, most preferred 2,3 to 2,7.

Embodiment 4

Process according to any of Embodiments 1 to 3, wherein at least one stabilizer is included in step a)-cc), such stabilizer being a non-ionic surfactant with a HLB-value of at most 10, preferably of at most 8, more preferably of at most 5, and even more preferably of at most 3, such as at most 2, and/or having an isoelectric pH-value which is such that the stabilizer is hydrophobic during the mixing of step f)) and also at about plus/minus 1-pH-value of the pH-value of the mixture upon mixing and is amphiphillic at a pH-value of more than 7, preferably at least at more than pH 8, such stabilizer preferably being selected from the group consisting of - each linear or branched - fatty alcohols, oxo-alcohol alkoxylates, fatty acid alcohol alkoxylates, poly alkylenoxides, alkyl celluloses, hydroxy alkyl celluloses, and other suitable water-in-oil-emulsifiers, more preferably being selected from non-ionic emulsifiers such as water-in-oil-type emulsifiers such as fatty alcohol such as cetyl alcohol (Lanette C® etc.), glycerol fatty acid esters such as for example glycerol monostearate, sorbitan fatty acid esters such as those of the product class SPAN® as for example sorbitan monolaurate, wool wax alcohols, macrogol fatty acid ethers such as poly ethylene glycol-2-oleylether as for example BRIJ® and BRIJ®92, and/or non-ionic emulsifiers such as oil-in-water-type emulsifiers such as macrogol fatty acid esters such as poly ethylene glycol-8-stearate as for example the product class MYRJ® and specifically MYRJ®45, macrogol glycerol fatty acid esters such as poly ethylene glycol-20-glycerol monostearate as for example the product class TAGAT® and specifically TAGAT®, macrogol sorbitan fatty acid esters (polysorbates) such as poly ethylene glycol-20-sorbitan monolaurate such as the product class TWEEN® and specifically TWEEN® 20, polyoxypropylene-polyoxyethylene-block-copolymers such as the product class Poloxamers and specifically Poloxamer 124, even more preferably sorbitol tri-fatty acids such as most preferably sorbitol tri oleate.

Embodiment 5

Process according to any of Embodiments 1 to 4, wherein at least one additive, which is preferably amphiphilic, is added in at least step in step a)-cc), such additive being selected from the group consisting of b) water-soluble polymers such as vinyllactam-homo- and copolymers, preferably homopolymers, more preferably of medium to low molecular weight of about 10.000 to 100.000 g/mol Mw, more preferably about 15.000 to 40.000 g/mole Mw such as polyvinylpyrrolidone of Fikentscher’s K-value 15, 20, 25, 30, 35, 40, 45, 50, 55 or 60, preferably of K-value 20 to 45 and specifically PVP K 15, PVP K 20, PVP K 25 and PVP K 30; copolymers of hydrophobic monomers with carboxylic-acid-monomers, preferably of a monomer-ratio of from 3:1 to 1 :3, preferably about 1 :1 , as hydrophic monomers preferably acrylic ester- or olefinic monomers of at least 3 carbon-atoms on the ester-side of the acrylic ester-monomers or at least 4 carbon-atoms of the olefinic monomers, and the carboxylic monomers being selected from acrylic acid, methacrylic acid (MAA), 2- ethylacrylic acid, 2-phenylacrylic acid, malonic acid, crotonic acid, maleic acid (or maleic anhydride), fumaric acid, itaconic acid, aconitic acid, mesaconic acid, citraconic acid, sorbic acid, cinnamic acid, methylene malonic acid, unsaturated C4-C10 dicarboxylic acids, and mixtures thereof, preferably copolymers having two monomers consisting of olefins and maleic acid-groups such as for example Sokalan® CP9 and similar polymers, and preferably Sokalan® CP9 ; and c) graft-polymers of poly-alkoxylene-homo- and co-polymers, preferably polyalkoxylene- homo-polymers such as PEG etc. or (block- or random) copolymers of ethylene oxide and propylene oxides, being grafted with vinyl esters, such as vinylacetate, vinylpropionate, vinyl butyrate etc, preferably vinyl acetate, and optional further monomers such as vinyllactams, preferably vinyl pyrrolidone, vinyl caprolactam, more preferably vinylpyrrolidone, but possibly although not preferred also other monomers such as vinyl imidazole etc., preferably graft polymers on poly alkylene oxide (such as preferably poly ethylene glycol) as graft base and vinyl actetate as sole monomer, the PEG being preferably of molecular weight 2000 to 8000 such as preferably about 6000 g/mol, and the ratio of PEG to vinyl acetate (in weight percent ratio) being in between 20:80 and 80:20, preferably about 50:50 to 70:30 such as 60:40, the graft polymer being preferably dissolved or solubilized in an aqueous medium such as water or mainly water or in suitable liquid surfactants such as those of the Lutensol®-type; most preferably graft polymers on poly ethylene glycol as graft base and vinyl actetate as sole monomer, the PEG being preferably of molecular weight of about 6000 g/mol, and the ratio of PEG to vinyl acetate (in weight percent ratio) being in between about 50:50 to 70:30 such as most preferably about 60:40, the graft polymer being preferably dissolved or solubilized in an aqueous medium, water, mainly water or suitable liquid surfactants, preferably those of the Lutensol®-type; d) naturally-derived compounds, such as gelatin-derivates such as gelatin type A (i.e. partially degraded gelatin using acids), starch derivates, such as starch ethers and starch esters, preferably starch esters such as starch succinoleat, starch acetate and their mixtures; such additives preferably being bio-degradable to at least 30, more preferably at least 50, even more preferably at least 80 and most preferably to about 100 percent (as tested under standard conditions).

The copolymers of Embodiment 5 b) are preferably the following:

The copolymer is consisting of at least one monomer selected from the group consisting of acrylic acid, methacrylic acid (MAA), 2-ethylacrylic acid, 2-phenylacrylic acid, malonic acid, crotonic acid, maleic acid (or maleic anhydride), fumaric acid, itaconic acid, aconitic acid, mesaconic acid, citraconic acid, sorbic acid, cinnamic acid, methylenemalonic acid, unsaturated C4-C10 dicarboxylic acids, and mixtures thereof, and at least one hydrophobic monomer selected from the group consisting of isobutene, diisobutene, butene, pentene, hexene and styrene, olefins with 10 or more carbon atoms or mixtures thereof; preferably, the copolymer is partially or completely neutralized using typical, suitable bases such as NaOH, KOH etc. to form the alkali metal salts of such (co-)polymers; even more preferably, the copolymer is consisting of at least one monomer of formula I, selected from the group consisting of acrylic acid, methacrylic acid (MAA), 2- ethylacrylic acid, 2-phenylacrylic acid, malonic acid, crotonic acid, maleic acid (or maleic anhydride), fumaric acid, itaconic acid, aconitic acid, mesaconic acid, citraconic acid, sorbic acid, cinnamic acid, methylenemalonic acid, unsaturated C4-C10 dicarboxylic acids, and mixtures thereof, and at least one hydrophobic monomer selected from the group consisting of isobutene, diisobutene, butene, pentene, hexene and styrene, olefins with 10 or more carbon atoms or mixtures thereof; most preferably, the copolymer is consisting of maleic acid (which may be derived from polymerizing maleic acid or maleic anhydride) and at least one hydrophobic monomer selected from the group consisting of isobutene, diisobutene, butene, or mixtures thereof, preferably only diisobutene, and also preferably is partially or completely neutralized using suitable bases such as NaOH or KOH to form the alkali metal salts of such copolymer; the copolymer usually is provided as an aqueous solution, with solid contents of about 10 to 40, preferably about 20 to 30 weight percent; the copolymer typically has a Fikentscher’s K-value from 20 bis 80, preferably 25 bis 60, more preferably 30 bis 50 and even more preferably 35 bis 45, such as 40.

Embodiment 6

Process according to any of Embodiments 1 to 5, wherein the amount of stabilizers) within the feed mixture is in the range of from 0,01 to 1 , preferably 0,05 to 0,5 weight percent, and such that the amount of the stabilizer(s) in the mixing zone is in the range of from 0,01 to 1 , preferably 0,05 to 0,3 weight percent, each “weight percent” being based on the total weight of the respective mixture, preferably the stabilizer is added to the feed mixture and/or solvent mixture prior to addition to the mixing zone and/or prior to step k) (i.e. subjecting the CA-dispersion resulting from a previous step to a means imparting a certain amount of shear energy) and thus prior to the addition of the dispersion to the step exerting shear energy, preferably at least prior to the addition of the dispersion to the step exerting shear energy.

Embodiment 7

Process according any of c Embodiments 1 to 6, wherein the optional process step h) (i.e. “removal of solvent(s)”) is employed, and the process measure for this step is selected from the group of thermal distillation or steam distillation using water vapor (steam) or mainly nitrogencontaining gas vapor, at ambient, preferably by thermal distillation or steam distillation using water vapor, more preferably thermal distillation, reduced or over-pressure of at most 2 bar absolute pressure, preferably is performed at ambient or reduced pressure, and more preferably at ambient pressure, and even more preferably using steam at ambient pressure, to reduce the content of the organic solvent to a content of at most 1 weight percent, preferably at most 0,5 weight percent, and more preferably at most 0,2 weight percent and most preferably to at most 0,1 weight percent, based on the total weight of the cellulose dispersion to be obtained.

Embodiment 8

Process according any of Embodiments 1 to 7, wherein the process step k) (i.e. “exertion of shear energy”) is employed, and the means to impart shear energy for this step preferably is selected from the group comprising ultrasound generating devices, high-shear-imparting mills and colloid mills, high-shear grinders, for large-scale productions most preferably stirrer-type devices, such as dispersion disk, disc-type stirrers and oblique blades.

Embodiment 9

Process according to any of Embodiments 1 to 8, wherein the addition of the solvent mixture in step c) and the addition of the feed mixture in step d) to said mixing zone are each independently from each other performed as continuous addition, and wherein the addition is performed in parallel, and the mixing zone is a continuous mixing zone such a continuously run tubular mixer ortubular reactor with at least one mixing insert, the mixing being accomplished by suitable mixing devices such as mixing bars, stirrers, flow disruptors, fixed installations within a reactor and the like, preferably more preferably a tube-reactor with flow disruptors, for example (continuous) gear mixers (e.g. the so-called “Zahnkranzmischer”, e.g. supplied by company Kinematica, Switzerland). Embodiment 10

Process according to any of Embodiments 1 to 9, wherein during the addition of the feed mixture (step d)) and the solvent mixture (step c)) to the mixing zone at least one further additive (other than the additives as defined in previous Embodiment 5) is added, either as further third stream or admixed within the solvent mixture or the feed mixture either prior to or during the addition of such solvent mixture and/or feed mixture, preferably within the solvent mixture, wherein the at least one further additive is selected from the group consisting of optical brighteners, pigments, colours, UV-absorbers, UV-filters, and other typical cosmetic ingredients, with the proviso that they have to be compatible, i.e. do not chemically alter itself upon contact with the solvents employed, and do not chemically alter the CA employed.

Embodiment 11

Cellulose-acetate-dispersion (CA-dispersion) obtainable by the process according to any of Embodiments 1- 10, preferably being bio-degradable under standard conditions to at least 30, more preferably at least 50, even more preferably at least 80, and most preferably to about 100 percent by weight based on the solid content of the CA-dispersion.

Embodiment 12

Cellulose acetate-dispersion (CA-dispersion) having a) a low organic solvent content of at most 3 weight%, preferably of at most 1 wt.%, more preferably at most 0,5 wt.% and most preferably at most 0,1 wt.% of total organic solvent(s) based on the total weight of the CA-dispersion such as at most 0,05 weight percent, and even at most 0,02 weight percent or even less to essentially “zero”, b) a medium particle size of the dispersed cellulose acetate-particles of at most 80, preferably at most 20, more preferably at most 15, even more preferably at most 10 and most preferably at most 5 micrometer, such as from 1 to 4 micrometer, as measured as defined in the specification, c) a transmittance of 532nm-wavelength-light of at least 20, more preferably at least 30, even more preferably at least 35 and most preferred at least 40 % when measure as a 0,01wt%. dispersion in water, and d) a pH of in between 2,5 and 9, preferably at least 4, more preferably at least 6, and most preferably at least 6,5, and preferably up to 8,5, more preferably up to 8, more preferably up to 7,5, e) a density of from 0.95 to 1.15 g/mL measures as 10wt.%-dispersion (based on solid content), and f) a viscosity of from 50 to 1500 mPas, preferably up to 1000, more preferably up to 500, even more preferabby up to 300 mPas (Brookfield, spindle 3 at 20 revolutions per minute (“rpm”); measured as 5, 7,10, 12 or even 15 wt.%-dispersion (based on solid content; concentration as applicable by measurement, preferably measured at about 10 wt.%).

Embodiment 13

Use of the CA-dispersion according to Embodiment 11 or 12 or obtained by the process of any of Embodiments 1 to 10, in formulations or compositions within the field of application of fabric and home care, industrial and institutional cleaning, cosmetics, personal care, lacquer and colorants formulations, technical applications, agricultural formulations, in each application preferably as opacifier to impart opacity to such formulations and compositions. Embodiment 14 Use according to Embodiment 13 as opacifier in formulations or compositions within the field of application of fabric and home care, industrial and institutional cleaning, cosmetics, personal care, preferably fabric and home care, industrial and institutional cleaning, more preferably fabric and home care.

Embodiment 15

Use according to Embodiment 13 or Embodiment 14, wherein the CA-dispersion is employed in amounts of from 0,02 to 5, preferably 0,05 to 2, more preferably 0,1 to 1 ,5, even more preferably from 0,5 to 1 ,5, most preferably from 0,7 to 1 ,2, such as from 0,8 to 1 ,1 and such as about 1 weight percent, all numbers being weight percentages based on the total weight of the formulation.

In a further embodiment, the CA employed may contain a basic salt selected from the group of hydroxides, carbonates, hydrogen carbonates and/or oxides of alkali metals earth alkali metals and/or zinc, especially those of sodium, kalium, magnesium, calcium and/or zinc. In an alternative embodiment such salts may be added to the CA-dispersion during the process of the present invention, especially at any time during the process as defined by Embodiments 1 to 10. Preferably, such salt(s) is(are) added within or directly before and/or after process step d), e) and/or f), preferably during or before step d) and/or e), more preferably before or during step d), even more preferably during step d).

Those salts are employed to promote the biodegradation of the CA to increase the biodegradation performance of the inventive CA-dispersion and their powders in case dried.

The following terms have their ordinary meaning unless specifically defined otherwise within this disclosure:

Molecular weight descriptors Mw, Mn and polydispersity (PDI as polydispersity index) of the molecular weight; HLB-value (also sometimes named hydrophilic-lipophilic balance); protic, aprotic, amphiphilic; pH-value; shear energy.

All percentages given are weight percentages based on the total weight of that composition, dispersion, feed, mixture etc., unless specifically defined otherwise; abbreviated as “wt%”.

“Additive”, “Stabilizer”: are defined within the embodiments, the description of this present invention including its claims.

“About” means that the numerical value given may deviate from “plus/minus” 10 percent (i.e. meaning “from 90 to 110 %”) of the value shown, but preferably deviates only from plus/minus 5, even more preferably only plus/minus 3 percent or even only 2 or even 1 percent or - as most preferred option - may be exactly the number given.

“Finely dispersed”: means that the particles dispersed in the medium do not form agglomerates having diameters of more than 125 micrometer, i.e. can pass through a filter of 125 micrometer filter. Preferably, this term means that the agglomerates are smaller than 100 micrometer, and even more preferably the amount of agglomerates is less than 10 percent of the total weight of the solid content based on the weight of CA present.

“Removable with a 125 micrometer filter” means that the particles dispersed in the medium cannot pass through a filter of 125 micrometer pore size (defined as cut off) and thus are removed by such filter from the liquid medium being filtered. . Similarly, “removable with a 190 micrometer filter” means that this test is performed using a 190 micrometer pore size (defined as cut off).

“Bio-degradable”, “biodegradation” with or without the addition of “as tested under standard conditions” mean the biodegradation and - if percentages are given such as “30% bio- degradation/bio-degradable” of the mentioned substance, compound or formulation, which has been determined using biodegradability tests according to ISO14851 or ISO14852 (both in water) (in case of differing results, and when both test conditions are applicable and possible to be used, the test according to ISO14851 shall be the decisive one) or according to ASTM D.6691 (in marine water) or according to ISO17556 (in soil).

“Medium particle size” and the corresponding “medium particle size measurement” means the particle size D[4,3] as measured using a Malvern Mastersizer 2000 in aqueous environment using standard methods and ingredients. The Mastersizer used for the present invention was equipped with a Hydro 2000S (a) as accessory, using water as dispersant, at a concentration of 0,0220 volume percent.

“Transmittance of 532nm-wavelength-light” means the transmittance measured with a wave length of 532 nm light using standard machines, such as preferably Hach Lange DR6000 spectrometer, compared to the transmittance of the standard, which usually is plain water suitable for such measurement, preferably being distilled or even bi-distilled water, at a concentration of 0,01 wt.% and a cuvette of 1 centimeter length of dispersion for the rays to pass through.

Generally, as used herein, the term “obtainable by” means that corresponding products do not necessarily have to be produced (i.e. obtained) by the corresponding method or process described in the respective specific context, but also products are comprised which exhibit all features of a product produced (obtained) by said corresponding method or process, wherein said products were actually not produced (obtained) by such method or process. However, the term “obtainable by” also comprises - and preferably means - the more limiting term “obtained by”, i.e. products which were actually produced (obtained) by a method or process described in the respective specific context.

The process to produce the CA-dispersion employs suitable devices imparting shear energy to produce the dispersion and thus fine particles of CA. Also, the step of further micronisation after the production of the initial CA-dispersion to be obtained from the initial dispersion-forming process part employs suitable devices imparting even higher shear energy than the initial dispersion-forming process part.

Suitable devices for both process steps are known in the art., such as rotor-stator-devices including toothed submerges rings, toothed inline rings, conche and shear pumps, stirrer devices such as dispersion discs, other disc-types and oblique blades, or static devices such as orifice, static mixer, and devices using ultrasonic sound. The present invention employs for the initial dispersion-forming process step preferably dispersion means in the form of stirrers, more preferably those following:

Stirrer-type devices, such as dispersion disk, disc-type stirrers and oblique blades, which are known by e.g. company Netzsch, e.g. the Mastermix Dissolver, and company RVT-Systeme e.g. the disc-type stirrers or oblique-blade stirrers.

The present invention employs for the micronisation step of the CA-dispersion obtained from the initial dispersion-forming process step, which aims at obtaining smaller particle sizes and a more narrow particle size distribution, dispersion means preferably in the form of roto-stator devices or static devices or wave-imparting devices, for smaller scale processes more preferably waveimparting devices, and most preferably such that operate using ultrasound, and for large-scale processes more preferably those in form of the stirrer-type devices (as defined and exemplified before).

The process of the present invention employs - on lab scale - ultrasound for at least 3, preferably at least 4 minutes, but no more than 15 minutes, preferably no more than 12 minutes, and even more preferably no more than 10 minutes, “on lab scale” means scales as those exemplified by the examples as shown in the experimental section of this present disclosure.

Of course, it is obvious to a person of skill in the art that the duration also usually depends on the scale and the equipment employed. Hence, adjusting the duration in view of the employed equipment and the scale at which the application of ultrasound is exerted on the medium (i.e. if done in a tank or in a small tubular loop through which the medium is passed through once or - preferably - several, more preferably many times) is well within the knowledge and can be easily adjusted measuring the particle size distribution in one example over time, as done in one example shown below in the experimental section.

By this, narrow particle size distributions and small particle sizes, and preferably also not containing agglomerates of more than 125 micrometer maximum diameter, can be obtained, such as those defined in the embodiments herein.

The CA-dispersions of the present invention may be advantageously employed in formulations or compositions within the field of application of fabric and home care, industrial and institutional cleaning, cosmetics, personal care, lacquer and colorants formulations, technical applications, in each application preferably as opacifier to impart opacity to such formulations and compositions.

Compositions for Fabric and Home Care

Such compositions and formulations include those designed for cleaning soiled material or surfaces of any kind, including but not limited to laundry cleaning compositions and detergents, fabric softening compositions, fabric enhancing compositions, fabric freshening compositions, laundry prewash, laundry pretreat, laundry additives, spray products, dry cleaning agent or composition, laundry rinse additive, wash additive, post-rinse fabric treatment, ironing aid, dish washing compositions, hard surface cleaning compositions, unit dose formulation, delayed delivery formulation, detergent contained on or in a porous substrate or nonwoven sheet, and other suitable forms that may be apparent to one skilled in the art in view of the teachings herein. Such compositions may be used as a pre-laundering treatment, a post-laundering treatment, or may be added during the rinse or wash cycle of the laundering operation. The cleaning compositions may have a form selected from liquid, powder, single-phase or multi-phase unit dose, pouch, tablet, gel, paste, bar, or flake.

Industrial and institutional cleaning

Such compositions and formulations include those designed for cleaning soiled material or surfaces of any kind, such as hard surface cleaners for surfaces of any kind, including tiles, carpets, PVC-surfaces, wooden surfaces, metal surfaces, lacquered surfaces.

As used herein the phrase "cleaning composition" includes compositions and formulations designed for cleaning soiled material. Such compositions include but are not limited to, laundry cleaning compositions and detergents, fabric softening compositions, fabric enhancing compositions, fabric freshening compositions, laundry prewash, laundry pretreat, laundry additives, spray products, dry cleaning agent or composition, laundry rinse additive, wash additive, post-rinse fabric treatment, ironing aid, dish washing compositions, hard surface cleaning compositions, unit dose formulation, delayed delivery formulation, detergent contained on or in a porous substrate or nonwoven sheet, and other suitable forms that may be apparent to one skilled in the art in view of the teachings herein. Such compositions may be used as a prelaundering treatment, a post-laundering treatment, or may be added during the rinse or wash cycle of the laundering operation. The cleaning compositions may have a form selected from liquid, powder, single-phase or multi-phase unit dose, pouch, tablet, gel, paste, bar, or flake.

Preferably, the cleaning compositions of the present invention are those for the field of laundry cleaning compositions and detergents for laundry and hand dish cleaning compositions. More preferably, cleaning compositions of the present invention are liquid compositions for use within the field of laundry and hard surface cleaning, such as liquid laundry detergents and liquid dish washing cleaning compositions, such as preferably for hand dish washing and for laundry.

The cleaning compositions may also contain adjunct cleaning additives. Suitable adjunct cleaning additives include builders, structurants or thickeners, clay soil removal/anti-redeposition agents, polymeric soil release agents, polymeric dispersing agents, polymeric grease cleaning agents, enzymes, enzyme stabilizing systems, bleaching compounds, bleaching agents, bleach activators, bleach catalysts, brighteners, dyes, other hueing agents, dye transfer inhibiting agents, chelating agents, suds supressors, softeners, and perfumes. All of those substances that may be typically employed within such cleaning compositions are known to the person of skill in the art.

Cosmetics, Personal Care

Such compositions and formulations include shampoos, lotions, gels, sprays, soap, make-up powder, lipsticks, hairspray.

Lacquer and Colorants formulations

Such compositions and formulations include non-water- and - preferably - water-based lacquer and colourants, paints, finishings.

Technical applications

Such compositions and formulations include glues of any kind, non-water and - preferably - water-based liquid formulations. Agricultural Formulations

Such compositions and formulations include formulations and compositions containing actives within a liquid environment

In each of the before application areas and their compositions and formulations the CA-dispersion of the present invention is preferably employed as opacifier to impart opacity to such formulations and compositions, such as for example to impart turbidity to an otherwise clear liquid formulation or a formulation which contains undissolved or emulsified ingredients and thus to “hide” those undissolved or emulsified parts of the composition or formulation by imparting turbidity and thus making such parts less visible, or - in case of clear (and preferably also colorless or only of faint colour) formulations or compositions to increase the visibility by imparting turbidity. Turbidity may be also employed to vary the visual observation of a colour by imparting turbidity and thus creating a different perception of such colour by increasing the amount of scattered light and thus for example intensifying the colour, reducing shininess or else.

The following examples shall further illustrate the present invention without restricting the scope of the present invention.

Examples

Transmittance (also “LD-value”)

Wave length: 525 nm; concentration: 0.01 %; cuvette: 1 cm; apparatus: Hach Lange DR6000 spectrometer.

Cellulose Acetate (CA) employed was the following: (details see Table 1)

Cellulose acetate (CAS: 9004-35-7), obtainable e.g. from Sigma and other commercial sources.

Table 1 : Overview of CA-samples used:

*Brookfield-Viscosity: 10% cellulose acetate in acetone. RV Spindle 4 Z *20 Upm;

Characterization of cellulose acetate (CA):

CA-1 : Molecular mass distribution by gel permeability chromatography: Mn: 32 000; Mw 97

800; Polydispersity PD: 3.1

Acetyl content: 40 w%

Degree of substitution (“DS”) by 13C-NMR in D6-DMSO: 2.45 The CA-samples 2-5 were characterized in a similar manner.

The general synthetic procedure of making a CA-dispersion according to the invention is described below.

Experiments using CA-4 and CA-5 have been performed similarly as the inventive examples; the experiments using CA-4 and CA-5 however had to be stopped after the step f) (the mixing step) due to such high amounts of coagulate that the “dispersion” was no dispersion anymore but a mixture of various phases with high amounts of undispersed CA or extremely large dispersion droplets. Hence, the further work-up had to be stopped.

Chemicals employed

Acetone; density 0.784 g/ml

Stabilizers:

C13/15-Oxoalkokolethoxylate with 3 Ethylene oxide (Lutensol® AO3, BASF); C13/15- Oxoalkokolethoxylate with 5 Ethylene oxide (Lutensol AO5, BASF; C16/18- Fettyalkoholethoxylate with 18 Ethylene oxide (Lutensol AT18, BASF; Methylcellulose (Methocel A15C; Dow); Hydroxypropyl methylcellulose (Methocel E15; Dow)

General synthetic procedure I Example 1

A mixture of water and acetone (as pre-charge = “solvent mixture”) was prepared in a 4000 ml glass vessel. The mixture was stirred with 150 pm at 25 °C. Within 60 minutes a solution of cellulose acetate CA-1 (20.0 g) in a mixture of acetone and water (= “feed mixture”) and stabilizer was fed to the pre-charge. Within a specific rate a feed of water (435.0 g) (= “further feed”) was added in parallel

Thereby the total ratio of acetone and water was kept constant in the reaction mixture.

After dosage of the cellulose acetate feed, the reaction mixture was distilled at 50 °C/450 mbar to remove the acetone. To concentrate the dispersion water was removed at 50 °C/50 mbar.

The resulting white dispersion had a solid content of about 10 w% and a particle size distribution of d (0.1): 4-6 micrometer; d (0.5): 10-20 micrometer; d (0.9): 20-50 micrometer.

The procedure of Example 1 /general procedure was followed for all following examples shown in the tables 2, 3 and 4 below, which show the details including the variation of the stabilizer and the effect of the polymeric colloidal stabilizers.

Application of Ultrasound:

A reproduction of example 7 and the results of using ultrasound to further disperse the CA is shown below as example for the inventive process:

Particle size distribution (PSD) before and after storage for 14 days at room temperature

Ultrasound-experiment 1 : no application of ultrasound

Ultrasound-experiment 2: ultrasound for 10 minutes and no storage

Ultrasound-experiment 3: ultrasound for 10 minutes; results after storage for weeks Ultrasound-experiment 4: no ultrasound, storage for 14 days at room temperature Ultrasound-experiment 5: time-dependency of particle sizes on ultrasound duration

Figures 1 to 5 correspond to the ultrasound-experiments 1 to 5 and show the results. The Tables 5, 7 and 8 below show the results in numbers.

Explanation on Figure 5: red (curve to the left) = after 10 minutes ultrasound; green (curve with second peak from the left) = after 5 minutes ultrasound; light blue (curve with peak third from the left) = after 3 minutes ultrasound; dark blue (curve with fourth peak from the left) = after 2 minutes ultrasound; purple (curve with fifth peak from the left) = after 1 minute ultrasound; orange (curve with sixth peak from the left) = before ultrasound

The other inventive examples show very similar if not identical behavior and results when subjected to ultrasound under the same or very similar conditions.

As a general guideline to be taken from the experiments, the application of ultrasound should last at least about 4 minutes. At about 10 minutes a plateau can be reached and thus further applying ultrasound beyond more than about 10 minutes does not improve the PSD any further to any significant improvement (note: this is data for laboratory scale; i.e. depending on the scale a longer application of ultrasound might be necessary; such duration can be tested by similar experiments to find the optimal duration depending on the scale and the apparatus employed for exerting ultrasound).

As an overall conclusion, it can be seen that the particle size distribution (PSD) remains stable even upon storage.

Characterization of inventive CA-dispersions

Table 5: Viscosity profile of inventive CA-dispersions according to solid content Particle Deagglomeration

A sample of the CA-dispersion prepared according to Example 7 was examined for deagglomeration: filtration using 190pm filter resulted in no coagulate; solid content 10,3 wt.%; Light transmittance (LD): 31%; pH 6,3. Results see Table 6.

Table 6

A sample of the CA-dispersion prepared according to Example 7 was examined for behavior upon application of ultrasound over time; 150 g of a 10wt.%-dispersion; 20% of max Amplitude 6.4 W for 5 min; ultrasonic equipment: Ultrasound processor UP 400s; by Dr. Hielscher GmbH; Power consumption 25.5 W max. Energy input: 3,56 Wh/kg; Results see Table 7.

Table 7

A sample of the CA-dispersion obtained in Example 10 was examined: 150 g 10% dispersion; 100% of max Amplitude 25,5 Wfor 5 min; ultrasonic equipment: Ultrasound processor UP 400s by Dr.

Hielscher GmbH; Power consumption 25.5 W max; Energy Input: 14,17 Wh/kg. Results see Table 8:

Table 8 Particle size distribution after deagglomeration

A CA-Dispersion as obtained from Example 10 was subjected to deagglomeration using ultrasound or high-pressure homogenizer.

Solid content: 11 ,8%, Light transmittance: 43.

Particle sizes - as shown in the following table particle sizes were measured using a Malvern Mastersizer 2000. Results see Table 9.

Table 9

The biodegradation values of some Cas as employed for the CA-dispersions have been tested according to ISO 14851 [d]; the biodegradation values are compared relative to pure cellulose; results are shown in Table 10.

Table 10

Application of inventive CA-dispersions

Turbidity and Biodegradation in liquid detergent formulations

CA-dispersions of the invention resulting from Example 7 and Example 10 were employed in two general types of detergent formulations (formulation 1 (Table 11) and formulation 2 (Table 12)) in the amounts specified in the Table 13 (percentages in weight percent based on the total weight of the formulation). Results see Table 13.

Table 11 : Formulation 1 - Liquid laundry formulation

Table 12: Formulation 2 - Hand dish wash detergent

Table 13

* Light shattering method; The units of turbidity from a calibrated nephelometer are called nephelometric Turbidity Units (NTU). Equipment: Hanna HI88703 (Accuracy ± 2%; Scale: 0.1-4000 scale formazine dispersions)