NZ626461B2

NZ626461B2 - Cellulose mixed esters, process for preparation and uses

Info

Publication number: NZ626461B2
Application number: NZ626461A
Authority: NZ
Inventors: Mark Glenny; Colin Gooch; Simon Hinkley; Jennifer Mason; Cameron Tristram; Dennis Williams
Original assignee: Resene Paints Limited
Priority date: 2011-12-05
Filing date: 2012-12-05
Publication date: 2017-01-05

Abstract

The disclosure relates to cellulose mixed esters of levulinic acid and an alkyl carboxylic acid such as acetic acid, propionic acid, butanoic acid, isobutanoic acid, pentanoic acid or hexanoic acid, processes for preparing these and uses of the cellulose mixed esters, for example in coating compositions. These cellulose mixed esters have glass transition temperatures that fall within an appropriate range to allow for film formation to occur at ambient temperatures and have a total degree of substitution per anhydroglucose unit of about 2.5 to about 3.5; a residual hydroxyl functionality per anhydroglucose unit of 0 to about 0.5; a degree of substitution per anhydroglucose unit by C2-C6 ester groups of about 0.5 to about 2.8; and a degree of substitution per anhydroglucose unit by levulinyl ester groups of about 0.2 to about 2.6. ions. These cellulose mixed esters have glass transition temperatures that fall within an appropriate range to allow for film formation to occur at ambient temperatures and have a total degree of substitution per anhydroglucose unit of about 2.5 to about 3.5; a residual hydroxyl functionality per anhydroglucose unit of 0 to about 0.5; a degree of substitution per anhydroglucose unit by C2-C6 ester groups of about 0.5 to about 2.8; and a degree of substitution per anhydroglucose unit by levulinyl ester groups of about 0.2 to about 2.6.

Description

CELLULOSE MIXED ESTERS, PROCESS FOR ATION AND USES TECHNICAL FIELD This invention s to cellulose mixed esters, processes for preparing these and uses of the cellulose mixed esters, for example in coating compositions.

BACKGROUND Cellulose esters are nown polymers that have found use in applications such as plastics, film and coatings. These types of esters have been used, for example, as film forming agents in solventborne coatings. Cellulose acetate butyrates , in particular, have been extensively investigated for use in coatings. Other known cellulose esters incorporate different functional groups, such as carboxylate functionalities, to alter the properties of the esters or to provide sites for further reaction and manipulation of the functional groups. describes cellulose mixed esters which have a high m degree of substitution and comprise acetyl groups as well as C 3-C4 esters. They are said to be useful in coatings ations, for example as the major components in high solids or low VOC compositions. WO 2007/145955 describes that such ose mixed esters, having both acetyl and C3-C4 ester functionalities, can be used to improve properties such as the gloss of a coating composition.

US 5,420,267 describes cellulose acetoacetate esters. These are mixed , comprising acyl groups and acetoacetyl . Edgar et al. report that a higher degree of acetoacetate substitution can lead to crosslinked films which t improved solvent and water resistance and hardness [K J Edgar, C M Buchanan, J S Debenham, P A Rundquist, B D Seiler, M C Shelton, D Tindall, Prog.

Polym. Sci. 26 (2001) 1605-1688].

A desirable feature for mixed cellulose esters which are to be used in coatings applications is that they can be formulated into a orne dispersion. However, examples of mixed cellulose esters having this property are uncommon as applied to coatings. US 3,220,865 describes a mixed cellulosic ester (CAB) formulation where the CAB (10-27% w/w) is emulsified into a 20-40% w/w formulation in the application of a coating suitable for wood surfaces.

One of the challenges for coatings applications is to produce cellulose esters which have a glass tion temperature (Tg) that falls within an appropriate range. In coatings applications, a number of factors, such as polymer size, degree of crosslinking and the presence of additives such as plasticisers can affect the T9 of the coating. The T9 itself influences properties such as adhesion and drying speed of the coating.

A ose mixed ester which is to be used as the principal binder in coatings, without added plasticisers or coalescing solvents, would preferably have a T9 which allows for film formation to occur at ambient temperatures. r, cellulose esters having glass transition temperatures in this range have proved elusive. For example, the cellulose mixed esters described in WO 2006/116367 and US 5,420,267 have glass tion atures that fall within the range 75.27 °C to 120.37 °C and 136 °C to 225 °C, respectively.

Current methods for lowering the T9, such as the addition of plasticisers or coalescing solvents, are not always desirable. This presents a problem, as, to date, no ose mixed ester is known which has a T9 that allows for film formation to occur at ambient temperatures without the addition of plasticisers or coalescing solvents.

However, the applicant has now found that chemical modification of cellulose esters can allow for control and manipulation of the T9. Such chemical modification can be achieved if, for example, one has access to a suitable cellulose ng material which incorporates onal groups that can be readily derivatised. A levulinyl group is one such functional group. describes ester derivatives of levulinic acid which are said to be useful as plasticisers and/or coalescing solvents in polymer compositions. WO 2007/094922 also describes a method for lowering the glass transition temperature of a polymer composition by adding to it a levulinic acid ester tive. Among the esters contemplated are those comprising a levulinyl group covalently bound to, inter alia, polysaccharides such as cellulose.

This document describes/the hydrolysis of corn fibre and the synthesis of levulinic acid ester derivatives of the polysaccharide and polyol residues of the hydrolysis. However, the document does not describe suitable cellulose mixed ester startingmaterials that could be employed in the synthesis of chemically modified cellulose esters.

The production of a mixed ester containing nic acid was also reported as a tic product of cellulose [Vladimirova aikh, Peker and Rogovin Polym.Sci. USSR. 7 (1964) 868-873]. While explicit mental data was not reported, the methodology required the use of highly d pre-treated ose starting materiel (viscose silk). In the inventor’s hands, the reported reaction conditions with perchloric acid failed to e a highly tuted mixed- ester cellulose derivative. Furthermore, the mixed ester produced by Vladimirova, when significantly more perchloric acid was used, was found to be unsuitable, have very poor solubility (especially on storage) and a high Tg (120°C). Further, the methodology of Vladimirova has been found not to work with less refined cellulose or pre-substituted cellulose starting material and it is not possible to tune the molecular size. The work of Vladimirova et a/. shows the difficulty in producing mixed esters suitable for use in coatings.

Another challenge of coatings applications utilising ose esters is to provide solubility characteristics and properties that prevent ready dispersion or emulsification of the polymer. A cellulose ester that has a further reaction site that is suitable for tuning solubility and emulsifying properties is highly desirable. For example, the opportunity to tune the acid-number of the polymer such that stable emulsification, stable dispersion or even water solubility may be conferred onto the polymer back-bone.

There is therefore a need for cellulose esters, e.g. ose mixed esters that can be used as starting materials for preparing a variety of ose mixed ester derivatives, such as those which have glass transition temperatures that fall within an riate range to allow for film formation to occur at ambient temperatures. There is also a need for processes for making such cellulose esters. It is therefore an object of the invention to provide novel cellulose mixed esters, or to at least provide a useful ative.

SUMMARY OF THE INVENTION In a first aspect, the invention provides a cellulose mixed ester having: 0 a total degree of substitution per anhydroglucose unit of about 2.5 to about 3.5; o residual hydroxyl functionality per anhydroglucose unit of 0 to about 0.5; o a degree of substitution per anhydroglucose unit by C2-C6 ester groups of about 0.5 to about 2.8; and o a degree of substitution per oglucose unit by levulinyl ester groups of about 0.2 to about 2.6.

Preferably the cellulose mixed ester of the first aspect of the ion has a weight average molecular weight (Daltons) of about 800 to about 105,000. More preferably the cellulose mixed ester has a weight average molecular weight of about 5000 to about 50000, e.g. about 5000 to about 40000, e.g. about 5000 to about 30000, e.g. about 5000 to about 20000.

Preferably the ose mixed ester of the first aspect of the invention has a degree of polymerisation of from about 2 to about 250, e.g. from about 5 to about 200, e.g. from about 5 to about 100 e.g. from about 5 to about 30. In some embodiments, the degree of polymerisation is about 15 to about 50, e.g. about 20 to about 40, e.g. about 30.

WO 85397 In some embodiments of the first aspect of the invention, the ose mixed ester has a total degree of substitution per anhydroglucose unit of about 2.5 to about 3.3, e.g. 2.9 to about 3.2, e.g. about 3.0 to about 3.1.

In some embodiments of the first aspect of the invention, the cellulose mixed ester has a degree of substitution per anhydroglucose unit by levulinyl ester groups of about 0.5 to about 2.5, e.g. about 0.75 to about 1.9, e.g. about 0.8 to about 1.85.

In some embodiments of the first aspect of the invention, the cellulose mixed ester has a degree of substitution per anhydroglucose unit by C2-C6 ester groups of about 0.5 to about 2.5, e.g. about 1.1 to about 2.25.

Preferably the cellulose mixed ester of the first aspect of the ion has a degree of substitution per anhydroglucose unit by levulinyl ester groups of about 0.75 to about 1.9 and a degree of tution per anhydroglucose unit by C2-C5 ester groups of about 1.1 to about 2.25.

In some embodiments of the first aspect of the invention, the cellulose mixed ester has a total degree of substitution per anhydroglucose unit of about 2.9 to about 3.2, a degree of substitution per anhydroglucose unit by levulinyl ester groups of about 0.75 to about 1.9 and a degree of substitution per anhydroglucose unit by C2-C6 ester groups of about 1.1 to about 2.25.

Preferably the cellulose mixed ester of the first aspect of the invention has a weight average molecular weight (Daltons) of about 800 to about 105,000 and a total degree of substitution per anhydroglucose unit of about 2.9 to about 3.2, e.g. about 3.0 to about 3.1. More preferably the cellulose mixed ester has a weight average molecular weight of about 5000 to about 50000, e.g. about 5000 to 20000, and a total degree of substitution per oglucose unit of about 2.9 to about 3.2, e.g. about 3.0 to about 3.1.

Preferably the cellulose mixed ester of the first aspect of the invention has a degree of polymerisation of from about 2 to about 250, e.g. from about 5 to about 200, e.g. from about 5 to about 100 e.g. from about 5 to about 30, and a total degree of substitution per anhydroglucose unit of about 2.9 to about 3.2, e.g. about 3.0 to about 3.1. In some embodiments, the degree of polymerisation is about 15 to about 50, e.g. about 20 to about 40, e.g. about 30 and the total degree of substitution per anhydroglucose unit of about 2.9 to about 3.2, e.g. about 3.0 to about 3.1.

Preferably the cellulose mixed ester of the first aspect of the invention has a total degree of substitution per anhydroglucose unit of about 2.5 to about 3.3, e.g. about 2.9 to about 3.2, e.g. about 3.0 to about 3.1, and a degree of substitution per anhydroglucose unit by levulinyl ester groups of about 0.5 to about 2.5, e.g. about 0.75 to about 1.9, e.g. about 0.8 to about 1.85.

Preferably all of the C2-C6 ester groups of the ose mixed ester of the first aspect of the invention are C3, C4, C5 or C6 ester groups. Alternatively preferably all of the C2-C5 ester groups of the cellulose mixed ester of the first aspect of the invention are acetyl, propionyl, isobutyryl, l, valeryl or hexanoyl groups, more preferably acetyl (C2), propionyl (C3) or butyryl (C4) , still more preferably butyryl (C4) groups.

In a second aspect, the invention provides a cellulose mixed ester prepared as described in e 1.1 below.

In a third aspect, the invention provides a cellulose mixed ester prepared as described in Example 1.2 below.

In a fourth aspect, the invention provides a cellulose mixed ester prepared as described in Example 1.3 below.

In a fifth aspect, the invention provides a cellulose mixed ester prepared as described n Example 1.4 below.

In a sixth aspect, the invention provides a cellulose mixed ester prepared as described in Example 2 below.

In a seventh aspect, the invention provides a cellulose mixed ester prepared as described in any one of Examples 7.1, 7.2 or 7.3 below.

In some embodiments of the first to fifth s of the invention, the cellulose mixed ester has a glass transition temperature (T9) of about 45 °C to about 100 °C, preferably about 50 °C to about 100 °C, ably about 50 °C to about 80 °C, preferably about 60 °C to about 80 °C.

Preferably the T9 is ed by differential scanning calorimetry (DSC).

In an eighth aspect, the invention provides a process for preparing a cellulose mixed ester, including the steps of: (a) combining an alkyl carboxylic anhydride, levulinic acid and one or more acids selected from the group consisting of Bronsted acids; Lewis acids; or es thereof of Lewis acids with Bronsted acids; and (b) contacting the on mixture from step (a) with cellulose to produce a solution containing a cellulose mixed ester.

Preferably the Bronsted acids are ed from sulfuric acid, methanesulfonic acid, para- toluenesulfonic acid, and phosphoric acid. Preferably the Lewis Acids are selected from metal triflates, e.g. (A|(OTf)3, Yb(OTf)3, Gd(OTf)3), or, when the ed acid is oric acid, a Lewis acid must be present. ably, prior to step (b) the cellulose is contacted with water then an alkyl carboxylic acid such as acetic acid, propionic acid, butanoic acid, anoic acid, pentanoic acid or hexanoic acid, preferably acetic acid, propionic acid or butanoic acid, more preferably acetic acid or butanoic acid, to produce a swollen cellulose which is the cellulose used in step (b).

Alternatively it is preferred that, prior to step (b), the cellulose is contacted with water, then an alkyl carboxylic acid such as acetic acid, propionic acid, butanoic acid, pentanoic acid or hexanoic acid, then nic acid, to produce a swollen cellulose which is the cellulose used in step (b) .

It is further preferred that a chlorinated solvent is included in the reaction mixture in step (a).

Preferably the nated solvent is selected from the group consisting of romethane, chloroform, and 1,2-dichlorethane. ably the alkyl carboxylic anhydride is selected from the group consisting of acetic anhydride, propionic anhydride, isobutyric anhydride, butyric anhydride, valeric anhydride and hexanoic anhydride, more preferably acetic anhydride, propionic anhydride, isobutyric anhydride and c anhydride, still more preferably acetic anhydride and butyric anhydride.

Preferably the ose and the reaction mixture are heated at about 120 °C in step (b). More preferably the cellulose and the reaction mixture are heated at about 120 °C, or to reflux if a chlorinated solvent is present, for about 2 to about 6 hours in step (b). Alternatively, the cellulose and the reaction mixture are heated using microwave energy in step (b).

The process optionally includes the step of: (c) diluting the solution obtained in step (b) with an aqueous on containing magnesium acetate, sodium acetate, acetic acid or sodium bicarbonate to produce a diluted solution containing the cellulose mixed ester.

The process optionally further includes the steps of: 2012/000228 (d) mixing the diluted solution obtained in step (c) with water; and (e) recovering the cellulose mixed ester.

Preferably the cellulose mixed ester is recovered by filtration in step (e). The cellulose mixed ester may optionally be purified by dissolution in a solvent such as acetone or N- pyrrolidine, then precipitation of the cellulose mixed ester by adding water, and ry of the cellulose mixed ester, for example by filtration.

In a ninth aspect, the invention provides a cellulose mixed ester having: a a total degree of substitution per anhydroglucose unit of about 2.9 to about 3.3; o residual hydroxyl onality per anhydroglucose unit of 0 to about 0.5; . a degree of substitution per anhydroglucose unit by C2-C5 alkyl ester groups of about 0.5 to about 2.8; . a degree of substitution per anhydroglucose unit by R1 ester groups of about 0.2 to about 2.6; where R1 is a radical of formula (i): X where each X in the cellulose mixed ester is independently selected from the group consisting of: O, N-O-R2 and (=O)-R3, where R2 is CH3(OCH2CH2)2, CH3(OCH2CH2)3, CH3(OCH2CH2)6_11, benzyl, alkyl or alkylcarboxy; and R3 is CH3(OCH2CH2)2, CH3(OCH2CH2)3, CH3(OCH2CH2)5_11; provided that not all X groups in the cellulose mixed ester are 0.

Preferably the ose mixed ester of the seventh aspect of the invention has a weight average molecular weight of about 2000 to about 105,000. More preferably the cellulose mixed ester has a weight average molecular weight of about 2500 to about . e.g. 15,000 to 40.000.

Preferably the cellulose mixed ester of the seventh aspect of the invention has e of polymerisation of from about 2 to about 250, e.g. from about 5 to about 200, e.g. from about 5 to about 100 e.g. from about 5 to about 30. in some examples, the degree of polymerisation is about 15 to about 50, e.g. about 20 to about 40, e.g. about 30.

In some embodiments of the seventh aspect of the invention, the cellulose mixed ester has a total degree of substitution per anhydroglucose unit of about 2.9 to about 3.2, e.g. about 3.0 to about 3.1. 2012/000228 In some embodiments of the seventh aspect of the invention, the cellulose mixed ester has a degree of substitution per anhydroglucose unit by R1 ester groups of about 0.5 to about 2.5, e.g. about 0.75 to about 1.9.

In some embodiments of the seventh aspect of the invention, the ose mixed ester has a degree of substitution per anhydroglucose unit by C2-Cs ester groups of about 0.5 to about 2.5, e.g. about 1.1 to about 2.25.

Preferably the cellulose mixed ester of the seventh aspect of the invention has a degree of substitution per anhydroglucose unit by R1 ester groups of about 0.75 to about 1.9 and a degree of substitution per anhydroglucose unit by Cg-Ce ester groups of about 1.1 to about 2.25.

Preferably the cellulose mixed ester of the h aspect of the invention has a weight average molecular weight (Daltons) of about 2000 to about 105,000 and a total degree of substitution per anhydroglucose unit of about 2.9 to about 3.2, e.g. about 3.0 to about 3.1. More preferably the ose mixed ester has a weight average molecular weight of about 2500 to about 70000, e.g. about 15000 to about 40000, and a total degree of substitution per anhydroglucose unit of about 2.9 to about 3.2, e.g. about 3.0 to about 3.1.

Preferably the cellulose mixed ester of the seventh aspect of the invention has a degree of polymerisation of from about 2 to about 250, e.g. from about 5 to about 200, e.g. from about 5 to about 100 e.g. from about 5 to about 30, and a total degree of substitution per anhydroglucose unit of about 2.9 to about 3.2, e.g. about 3.0 to about 3.1. In some embodiments, the degree of risation is about 15 to about 50, e.g. about 20 to about 40, e.g. about 30 and the total degree of tution per anhydroglucose unit is about 2.9 to about 3.2, e.g. about 3.0 to about 3.1.

Preferably the cellulose mixed ester of the seventh aspect of the invention has a total degree of substitution per oglucose unit of about 2.5 to about 3.3, e.g. about 2.9 to about 3.2, e.g. about 3.0 to about 3.1, and a degree of substitution per anhydroglucose unit by R1 ester groups of about 0.5 to about 2.5, e.g. about 0.75 to about 1.9.

Preferably all of the C2-C6 ester groups of the cellulose mixed ester of the seventh aspect of the invention are C3, C4, C5 or C6 ester groups. atively preferably all of the C2-Ce ester groups of the cellulose mixed ester of the seventh aspect of the invention are acetyl, propionyl, isobutyryl, butyryl, valeryl or hexanoyl groups, more preferably acetyl (C2), propionyl (Ca) or butyryl (C4) groups, still more preferably butyryl (C4) groups.

WO 85397 In some embodiments of the seventh aspect of the invention. the cellulose mixed ester has a glass transition temperature (T9) of from about -20 °C to about 45 °C. Preferably the T9 is measured by differential ng calorimetry (DSC).

In a tenth aspect, the invention provides a cellulose mixed ester of formula (I): where: n is an r from 2 to 250; and each R in the cellulose mixed ester is independently selected from the group consisting of H, C2-C6 acyl and levulinyl; provided that not all R groups are H, and provided that not all R groups are C2-C5 acyl, and provided that not all R groups are selected from H and C2-C6 acyl.

In an eleventh aspect, the invention provides a cellulose mixed ester of formula (II): (II) where: n is an r from 2 to 250; and each R’ in the cellulose mixed ester is independently selected from the group consisting of H, C2—CB acyl and R1; where: R1 is a radical of formula (i) (i) where each X in the ose mixed ester is independently selected from the group consisting of: O, N-O-R2 and (=O)—R3; each R2 in the cellulose mixed ester is independently selected from the group consisting of CH3(OCHzCH2)2, CH3(OCH2CH2)3, CH3(OCH2CH2)6.11, alkyl, benzyl and alkcarboxy; and each R3 in the cellulose mixed ester is independently selected from the group consisting of CH3(OCH20H2)2.

CH3(OCHQCH2)3 and CH3(OCH20H2)5_11; provided that not all R’ groups are H, and ed that not all R’ groups are C2-C5 acyl, and provided that not all R’ groups are ed from H and Cz-Ce acyl.

In some embodiments of the above formulae (I) and (II), n is an integer from about 2 to about 250, e.g. from about 5 to about 200, e.g. from about 5 to about 100 e.g. from about 5 to about . In some embodiments, the degree of polymerisation is about 15 to about 50, e.g. about 20 to about 40, e.g. about 30.

In some embodiments of the above formula (II), each X is independently selected from O and N-O-RZ. In these embodiments, some X groups in the cellulose mixed ester are 0 and some are N-O-Rz, such that not all X groups in the ose mixed ester are the same.

In some embodiments of the above formula (II), each X is independently selected from O and N-NH-C(=O)-R3. In these embodiments, some X groups in the cellulose mixed ester are 0 and some are N-NH-C(=O)—R3, such that not all X groups in the cellulose mixed ester are the same.

In some of the embodiments of the above formula (II), where the ose mixed ester comprises R1 groups where X is O and R1 groups where X is N-NH-C(=O)-R3, about 50% to about 100% of the X groups in the cellulose mixed ester are N-NH—C(=O)-R3.

In some of the embodiments of the above formula (II), where the cellulose mixed ester comprises R1 groups where X is O and R1 groups where X is N—O-RZ, about 50% to about 100% of the X groups in the ose mixed ester are N—O-RZ.

In some embodiments of the above formulae (I) and (II) the C2-C6 acyl group is a Ca, C4, Cs or C5 ester group. Alternatively preferably the C2-C6 acyl group is acetyl, propionyl, isobutyryl, butyryl, valeryl or hexanoyl, more preferably acetyl (C2), propionyl (C3) or butyryl (C4), still more preferably butyryl (C4).

In still other embodiments of the above a (II), the cellulose mixed ester comprises R1 groups where X is O and R1 groups where X is N-NH-C(=O)-R3. In these embodiments, the Cz— Ce acyl groups are preferably acetyl, propionyl or butyryl, more preferably acetyl or l.

In yet other embodiments of the above formula (II), the cellulose mixed ester comprises R1 groups where X is O and R1 groups where X is N-O-RZ. In these embodiments, the C2-C6 acyl groups are preferably acetyl, propionyl or butyryl, more preferably acetyl or butyryl.

In some embodiments of the above formula (II), R2 is CH3(OCH2CH2)2, CH3(OCH2CH2)3, CH3(OCH2CH2)5-11, benzyl, l. or (CH2)1_11carboxy.

In some embodiments of the above formula (I), the cellulose mixed ester has a weight average molecular weight (Mw) of from about 5000 to about 50000, e.g. about 5000 to about 40000 e.g. about 5000 to about 30000, e.g. about 5000 to about 20000.

In some embodiments of the above formula (II), the cellulose mixed ester has a weight average lar weight (Mw) of from about 25,000 to about 70,000 e.g. about 15,000 to about 40,000.

In some embodiments of the above formulae (I) and (II), the cellulose mixed ester has a degree of polymerisation of from about 2 to about 250, e.g. from about 5 to about 200, e.g. from about 5 to about 100 e.g. from about 5 to about 30. In some embodiments, the degree of polymerisation is about 15 to about 50, e.g. about 20 to about 40, eg. about 30.

In some embodiments of the above formulae (I) and (II), the cellulose mixed ester has a total degree of substitution per oglucose unit of about 2.9 to about 3.3, e.g. about 3.0 to about 3.2, e.g. about 3.1.

In some’embodiments of the above formulae (I) and (II), the cellulose mixed ester has a residual hydroxyl functionality per anhydroglucose unit of 0 to about 0.4, e.g. 0 to about 0.3, e.g. 0 to about 0.2.

In some embodiments of the above formulae (I) and (II) the cellulose mixed ester has a degree of substitution per anhydroglucose unit of C2-CG acyl groups of about 0.5 to about 2.8.

In some embodiments of the above formula (II) the cellulose mixed ester has a degree of substitution per oglucose unit of R1 groups of about 0.2 to about 2.6, e.g. about 0.5 to about 2.0, e.g. about 0.7 to abOut 1.5, e.g. about 0.82.

In some embodiments of the above formula (I) the cellulose mixed ester has a weight average lar weight (Daltons) of about 800 to about 105,000 and a total degree of substitution per anhydroglucose unit of about 2.9 to about 3.2, e.g. about 3.0 to about 3.1. More preferably the cellulose mixed ester has a weight average molecular weight of about 5000 to about 50000, e.g. about 5000 to about 40000 e.g. about 5000 to about 30000 e.g. about 5000 to about 20000, and a total degree of substitution per anhydroglucose unit of about 2.9 to about 3.2, e.g. about 3.0 to about 3.1.

In some embodiments of the above formula (I) the cellulose mixed ester has a degree of polymerisation of from about 2 to about 250, e.g. from about 5 to about 200, e.g. from about 5 to about 100 e.g. from about 5 to about 30, and a total degree of substitution per anhydroglucose unit of about 2.9 to about 3.2, e.g. about 3.0 to about 3.1. in some embodiments, the degree of polymerisation is about 15 to about 50, e.g. about 20 to about 40, e.g. about 30 and the total degree of tution per oglucose unit of about 2.9 to about 3.2, e.g. about 3.0 to about 3.1.

In some embodiments of the above formula (l) the cellulose mixed ester has a total degree of substitution per anhydroglucose unit of about 2.5 to about 3.3, e.g. about 2.9 to about 3.2, e.g. about 3.0 to about 3.1, and a degree of substitution per anhydroglucose unit by nyl ester groups of about 0.5 to about 2.5, e.g. about 0.75 to about 1.9, e.g. about 0.8 to about 1.85.

In some embodiments of the above formula (II) the ose mixed ester has a weight average molecular weight (Daltons) of about 2000 to about 105,000 and a total degree of substitution per anhydroglucose unit of about 2.9 to about 3.2, e.g. about 3.0 to about 3.1. More preferably the cellulose mixed ester has a weight average lar weight of about 2500 to about 70000, e.g. about 15000 to about 40000, and a total degree of substitution per anhydroglucose unit of about 2.9 to about 3.2, e.g. about 3.0 to about 3.1. in some embodiments of the above formula (ii) the cellulose mixed ester has a degree of polymerisation of from about 2 to about 250, e.g. from about 5 to about 200, e.g. from about 5 to about 100 e.g. from about 5 to about 30, and a total degree of substitution per anhydroglucose unit of about 2.9 to about 3.2, e.g. about 3.0 to about 3.1. In some embodiments, the degree of polymerisation is about 15 to about 50, e.g. about 20 to about 40, e.g. about 30 and the total degree of substitution per anhydroglucose unit of about 2.9 to about 3.2, e.g. about 3.0 to about 3.1. in some embodiments of the above formula (ll) the cellulose mixed ester has a total degree of substitution per anhydroglucose unit of about 2.5 to about 3.3, e.g. about 2.9 to about 3.2, e.g. about 3.0 to about 3.1, and a degree of substitution per anhydroglucose unit by R1 ester groups of about 0.5 to about 2.5, e.g. about 0.75 to about 1.9.

In some embodiments of the above formula (ii) the cellulose mixed ester has a glass transition ature (T9) of from about -20 °C to about 45 °C. in some embodiments of the above formula (l) the cellulose mixed ester has a glass transition temperature (T9) of about 45 °C to about 100 °C, preferably about 50 °C to about 100 °C, preferably about 50 °C to about 80 °C, preferably about 60 °C to about 80 °C. Preferably the T9 is measured by differential scanning calorimetry (DSC).

In a twelfth aspect, the invention provides a composition comprising one or more cellulose mixed esters of the invention, e.g. one or more cellulose mixed esters of the first, , third, , fifth, eighth, ninth, tenth or th aspect of the invention, as defined above.

Preferably the ition comprises more than one cellulose mixed ester as defined above.

In a thirteenth aspect, the invention provides a coating composition comprising one or more cellulose mixed esters of the invention, e.g. one or more cellulose mixed esters of the first, second, third, fourth, fifth, seventh, eighth, ninth, tenth or eleventh aspect of the invention, as defined above. The coating composition may further comprise one or more solvents. The solvents may be selected from the group ting of water, ketones, esters, glycol ethers, alkyl pyrrolidones and DMSO. The coating composition may ally comprise one or more additives such as surface wetters, levelling agents, waxes, silicones, biocides, de-foamers, anticorrosive pigments, UV absorbers, crosslinking agents and/or rheology modifiers.

The coating composition may be a paint composition.

In a enth aspect, the ion provides a method for preparing a cellulose mixed ester of formula (II) as defined above, including the step of: (a) reacting a cellulose mixed ester of formula (I) as defined above with an alkoxyamine or an aryloxyamine or an acyl hydrazide to produce a cellulose mixed ester of formula (II).

It will be appreciated that any of the sub-scopes sed herein, e.g. with respect to total degree of substitution, residual hydroxyl functionality, degree of substitution per anhydroglucose unit by 02-06 ester groups and/or degree of substitution per anhydroglucose unit by nyl ester groups; or e.g. with respect to total degree of substitution, residual hydroxyl functionality, degree of substitution per oglucose unit by 02-05 ester groups and/or degree of substitution per anhydroglucose unit by R1 ester groups; or e.g. with respect to n and/or R; or e.g. with respect to n, R’, X, R', and/or R2; may be combined with any of the other sub-scopes disclosed herein to produce further opes.

DETAILED DESCRIPTION As used hereinafter, the term “cellulose—levulinyl mixed esters” refers to cellulose derivatives ning the levulinyl moiety, e.g. as described by formula (I) as defined above. As used hereinafter, the term lose mixed ester derivatives” refers to cellulose-levulinyl mixed esters 2012/000228 where a proportion of the levulinyl moiety has been further derivatised, e.g. as bed by formula (II) as defined above.

The skilled person will appreciate that not all R or R’ groups of the cellulosic polymer of formula (I) or formula (ii) are H, and not all R or R’ groups are 02-06 acyl, and not all R or R’ groups are H or C705 acyl, but that the cellulosic r ses at least some degree of substitution by levulinyl or R1 ester groups.

Those skilled in the art will recognise that other methodologies for the sis of a mixed or homogeneous cellulose ester polymer are applicable [Mulzer, Section 2.2 “Synthesis of Esters, Activated Esters and Lactones", and in Trost and Fleming, “Comprehensive Organic Synthesis" Volume 6 (1991). For example, the use of sodium levulinate and/or other carboxylic acid salts in a suitable solvent and/or the ce of additional base and/or activating agents. Or, for example the use of levulinyl-halides such as levulinyl chloride and/or other —acids as the esterifying agents to produce cellulosic ester derivatives.

The skilled person will also appreciate that the end groups of the cellulose mixed esters of the invention, e.g. those of formula (I) or formula (II), may also be esterified.

The present invention relates to cellulose-levulinyl mixed esters which are useful as ng materials for producing a variety of cellulose mixed ester derivatives.

The cellulose—levulinyl mixed esters all comprise 02-05 acyl , such as acetyl, proplonyl or butyryl groups, randomly substituted on the anhydroglucose units of the cellulose ne, to give C2—CG ester functionalities. The cellulose—levulinyl mixed esters r comprise levulinyl groups, randomly substituted on the anhydroglucose units of the cellulose backbone, to give levulinyl ester functionalities. The cellulose mixed ester derivatives further comprise levulinyl groups and radicals of either a (a) or formula (b), randomly substituted on the anhydroglucose units of the cellulose backbone, to give levulinyl ester functionalities and levulinyl derivative functionalities. Alternatively, the cellulose mixed ester derivatives further comprise radicals of either formula (a) and/or formula (b), randomly substituted on the anhydroglucose units of the cellulose backbone to give levulinyl derivative functionalities: N \ (a) (b) R2/ HN};O where R2 and R3 are as defined in a (ii).

The cellulose mixed ester derivatives and, indeed, the cellulose-levulinyl mixed ester starting materials themselves can be used in a variety of applications, such as coatings applications.

The invention also provides processes for the production of cellulose-levulinyl mixed ester starting materials and for the production of cellulose mixed ester derivatives from these starting materials.

Some of the cellulose mixed ester derivatives that can be produced using the starting materials and processes of the invention advantageously have glass transition temperatures that fall within the range 45 °C. This makes them particularly suited to coatings applications such as waterborne coatings, and film formation of these coatings can occur at ambient temperatures without the need for plasticisers or coalescing solvents.

A further advantage of the introduction to a ose ester of a ketone functionality is that in addition to further cation of the polymers solubility, hydrophobicity, glass transition temperature and other physical characteristics is that it provides chemical functionality le for cross-linking with conventional industry-standard film-modifiers such as adipic acid dihydrazide.

Thus, the invention provides an ly new route to a wide range of different cellulose mixed ester derivatives. The invention also s to coatings comprising these derivatives as binders.

Advantageously, the cellulose-levulinyl mixed esters and the cellulose mixed ester derivatives are d from ble resources.

The ion further provides methods for lowering the glass transition temperatures of cellulose-levulinyl mixed esters by reaction, with a suitable t, of the pendant carbonyl groups located on the levulinyl ester groups, to produce cellulose mixed ester derivatives which can have lower glass transition temperatures than the starting material. Thus, the invention also provides a route to the synthesis of a variety of cellulose mixed ester derivatives, having glass tion temperatures that allow for film formation to occur at ambient temperatures t the need for plasticisers or coalescing solvents. The applicant has therefore shown that it is possible to chemically modify cellulose-levulinyl esters to manipulate and modify their glass tion temperatures.

Those skilled in the art will appreciate that the cellulose-levulinyl mixed esters can undergo a wide variety of transformations. For example, the t yl groups can undergo reactions to form the following functional groups: alkyloxyamines, aryloxyamines and acyl hydrazides, alkylated and ed derivatives, reduced derivatives, alkyl acids, alkyl phosphates, sulfates, thioesters, acetals, a—halogenated derivatives or alkenes.

Those skilled in the art will also e that the range of cellulose mixed ester derivatives assed by the invention is not limited to those having the above-mentioned functional groups. However, in some preferred embodiments of the invention, the cellulose mixed ester derivatives have functional groups that are carbonyl derivatives, for example oxime or acyl hydrazide derivatives.

As described above, the ose-levulinyl mixed esters of the invention are useful ng als for the preparation of other cellulose mixed ester derivatives and, in some cases, are themselves useful, for example, as the binder in coatings applications.

Comparative experiments on the reaction of cellulose with levulinic acid and with other similar sized alkyl acids surprisingly show that the level of incorporation of the levulinyl group in the cellulose mixed ester products is approximately twice the level of incorporation of other similar sized alkyl acids (shown as BM. in Table 1). This enhanced incorporation of the levulinyl group is unexpected, and an understanding of the mechanism of this reaction would be advantageous as it would allow for fine-tuning of the reaction conditions to produce cellulose-levulinyl mixed esters having the desired degrees of substitution.

Table 1. Comparison of Levulinic Acid oration to Alkyl C4-, C5- and ds Incorporation“2 Acid Number of Carbons DAcy. nic 5 1.29 Butyric 4 0.74 Valeric 5 0.67 Hexanoic 6 0.56 7 Total D5 for all 3.05 -— 3.1. Acid to acetic anhydride molar ratio 1 : 1.33. 2 The Dacy. is calculated from products exemplified in e 1.2 and Examples 2 through 6.

The applicant has found that the mechanism of the reaction of cellulose and levulinic acid in the presence of acetic anhydride and a strong acid catalyst proceeds via ted lactones. A solution of acetic anhydride, levulinic acid and catalytic sulfuric acid rapidly forms, in an exothermic reaction, acetyl (5) and levulinyl (6) activated Iactones with trace B-angelica Iactone (4), as determined by NMR oscopy e 1). (nu-Angelica Iactone (3) may be recovered from the reaction mixture by vacuum distillation but [3- angelica Iactone (4) is the only s observed in the reaction mixture, which suggests that (3) is the c product whilst (4) may be considered the thermodynamic product.

Scheme 1. Proposed active ester species formed with levulinic acid, acetic anhydride and catalytic strong acid.1 0 D Wok oLav O (1) on 0 0 0 o ROH sto. + 4» ROM: 01 ROLev + A020 = 0%0 DH Acetylated active ester (5) Levulinated active ester (5) Levulinic acid (not observed) 0 OR w—Angelica Iactone (3) (S-Angalica Iactone (A) 1 Where R represents the ose polymer, alternative polyols, organic or inorganic species. s (2), reported as pseudo-levulinic acid (R H Leonard, Industrial and Engineering Chemistry, 48(8), 1330-1341 (1956)) and the mixed anhydride (1) (or for that matter levulinic anhydride) are not ed in the above reaction mixture (by NMR). Species (2) has previously been postulated as an intermediate or equilibrium species formed from nic acid (US 2,809,203; B V Timokhin, V A Baransky, G D Eliseeva, Russian Chemical Reviews, 68(1), 73-84 (1999)). Furthermore, under dehydrating conditions it would not be likely that this species reforms from the activated esters (5) and (6).

The mixture of active Iactones (5) and (6) and in trace amounts the angelica Iactones (3) and (4), in the presence of catalytic sulfuric acid, has a greater capacity for the inclusion of the levulinyl ester moiety in the cellulose ester than an equivalent mixed acetic / alkyl carboxylic acid anhydride solution (see Table 1 above). This ts the cellulose dissolution and propensity to react is enhanced by this reactive on compared to a simple or mixed anhydride solution of other similar sized alkyl acids. Prior to the present invention, it was entirely cted that such an ement would be observed. Thus, it is possible, using the process of the present invention, to r and fine-tune the reaction conditions to produce cellulose-levulinyl ester ng materials having degrees of substitution that fall in the desired range.

Thus, the use of the active ester mixture of (5) and (6) with trace (3) and (4), is a highly effective acylating agent and provides a novel and facile route to the cellulose-levulinyl mixed ester starting materials of the invention. t wishing to be bound by theory, the applicant postulates that reaction of cellulose hydroxyl groups with acylated active ester (5) at the lactone carbonyl generates a levulinated cellulose ester with concomitant expulsion of acetic acid. In a similar n, reaction at the acetyl carbonyl acetylates cellulose, releasing levulinic acid.

Preparation of cellulose-levulinyl mixed esters through the use of the activated Iactones as shown in Scheme 1 results in a cellulose-levulinyl polymer having an off-white to brown appearance. The dissolution of the cellulose into the on mixture and degree of esterification are dependent on reaction volume, proportion and type of reagents, acid catalyst amount and type, effectiveness of cellulose pre-swelling, temperature and reaction stirring. The following are some preferred conditions for the preparation of cellulose-levulinyl mixed esters: Table 2. Variables in the nyl esterification of cellulose Variable Preferred ions Cellulose swelling Pre-swelling that tely immerses the cellulose in the solvent.

Stirring for 2-16 hours.

Two solvent treatments including water, then acetic acid, then additional treatments as required by the desired product.

Proportion of acid catalyst Increased proportions enhance rate of acetolysis and generation of smaller chain (lower degree of polymerisation) cellulose mixed esters. increased proportions decrease ose mixed ester yield.

Preferred proportion: about 0 mol% per anhydroglucose unit.

Acid catalyst type Preferred ed acids: sulfuric acid or ic acids such as methanesulfonic or paratoluene sulfonic acid; or phosphoric acid (H3PO4 must be used in combination with a Lewis acid).

Preferred Lewis acids: A Lewis Acid such as a metal te e.g. Al(OTf)3, Yb(OTf)3 or Gd(OTf)3 that may be enhanced by the on of a ed acid, e.g. H3PO4.

Temperature red temperature: less than about 120 Most preferred temperature range: 40-85 °C.

TReaction rate is arbitrarily defined as the observed rate of cellulose dissolution into the on mixture. A rapid reaction of suitably pre-swelled cellulose is considered to be effected in <30 minutes, whilst a slow reaction is considered to take 16 hours.

The process of preparing the cellulose-levulinyl ester starting materials optionally includes the use of a co-solvent such as a chlorinated solvent. The presence of the co—solvent can reduce colour generation and speed the ution and esterification of the cellulose polymer. it has not previously been reported that such co-solvents can enhance the levulinyl activated-ester esterification of cellulose. The chlorinated solvents dichloromethane (DCM, BP 40 °C), chloroform (BP 61 °C), and 1,2-dichlorethane (DCE, BP 84 °C) or chlorinated ts of higher boiling point can be used in the process. With decreased reaction temperature, complete ution typically requires longer reaction times (e.g. 16 hours for DCM compared to 0.4-2 hours for DCE).

Under low acid, lower temperature (<80 °C), shorter reaction time (<30 minutes) or in the presence of low-boiling point co-solvents (e.g. DCM) a third species (7) (as shown in Scheme 1) may be observed as a constituent in the cellulose-levulinyl ester. The presence of this species is evidenced by two distinctive broad methyl resonances in the 1H NMR spectrum (CDCIg), observed at 6 1.55 and 1.65 ppm, that have a clear H-C correlation to methyl carbon resonances 6 25.1 and 23.1 ppm, respectively. In addition, an unexpected nary resonance at 5 ‘30 109.4 ppm, that has long range H-C ations to the aforementioned methyl groups, is consistent with a methyl-lactone moiety on the cellulosic polymer. Figure 5 shows the 1H NMR spectrum of the reaction product of pre-swelled cellulose with levulinic acid, acetic anhydride, sulfuric acid and 1,2-dichlorethane for m on time to effect dissolution. Figure 5 graphically demonstrates the assignment for each proton signal in the spectrum. The methyl—keto groups in the e and levulinate esters overlap and cannot be assigned unambiguously to the four peaks observed at5 1H 1.8-2—2 ppm. The spectrum is indicative of approximately one levulinyl ester per anhydroglucose units, and one methyl lactone per two anhydroglucose units. The identity of the moiety on each of the C2, C3 and CB positions is not specified. The presence of the cellulose-lactone constituent in the reaction mixture indicates that the ted lactones are indeed the acylating moieties ed in the As discussed above, many factors affect the reaction product. Thus, for a reaction completed with effective stirring and for the minimum time to effect cellulose dissolution with DCE present a significant amount of lactone moiety is observed on the cellulose polymer, whilst for a longer reaction time without stirring in the same reaction e very little e is observed on the cellulose polymer. This suggests that the methyl lactone may be considered the kinetic product whilst ester linkage is the thermodynamic product. Similarly, lower temperature reactions or short time reactions tend to se the relative amount of the lactone moiety.

The applicants have shown that the above-described reaction chemistry can successfully be applied not only to Oz esters, but also to higher alkyl acids in conjunction with the incorporation of the levulinyl group through active ester chemistry. Thus, the above description of‘the preferred conditions for the cellulose-acetyl levulinyl mixed ester also applies to the reaction with higher alkyl acids. In a similar fashion to the preparation of a cellulose-acetyl levulinyl mixed ester, the higher mixed esters of propionic, butyric, isobutyric, valeric and hexanoic acid demonstrate the applicability of this ion (Table 3).

Table 3. Mixed cellulose-levulinyl esters Alkyl ester Propionyl iso-Butyryl . .

The applicants have found that the T9 of the higher mixed esters decreases with increasing number of carbons on the alkyl ester group, appearing to reach a minimum at a valeryl (C5)- nyl cellulosic mixed ester. Advantageously, the present invention therefore provides ose mixed esters which have surprisingly low T9, making them suitable and desirable starting materials for the ation of cellulose mixed ester tives, and indeed for use themselves, for example in coatings applications. Clearly this significant decrease in T9 provides an advantage in that significantly less amelioration by further Tg lowering modification is required.

A key component of the ketone ting further modification is the introduction of acid functionality which promotes forming a stable dispersion and/or emulsion. A further inventive step we have discovered is that the inclusion of a carboxy functionality appears to impart roomtemperature film formation even with a relatively high T9. This may be due to partial solubility of the species in water. Hence having the nyl ketone permits a film-forming t even when the T9 is high if it is suitably modified. An example is demonstrated in our current state-of- the-art in examples 13.3 and 13.4.

Preferred embodiments of the invention are propionyl, butyryl and/or iso-butyryl — levulinyl cellulose mixed esters and propionyl, butyryl and/or tyryl — levulinyl cellulose mixed ester derivatives, most preferably butyryl or iso-butyryl-levulinyl cellulose mixed esters and butyryl or iso-butyryi — levulinyl ose mixed ester derivatives. These mixed esters provide the following onal ages: relative ease of cture, low cost of materials and comparative ease of work-up and product preparation.

The cellulose mixed esters are soluble in a variety of solvents, including those that are typically used in coating compositions. Solvents in which the cellulose mixed esters are soluble include ethyl cellosolve, cyclohexanone, chloroform, dibasic ester, N-methylpyrrolidone, pyridine, dioxane, acetone, acetic acid, acetic anhydride, tetrahydrofuran, dimethylsulfoxide, dimethylacetamide, butyl lactate, diacetone alcohol, ethyl acetate, methanol, dimethylformamide, methyl ethyl ketone and dichloromethane. Typically the ose mixed esters are soluble to at least 10% w/v in these ts.

The cellulose mixed esters of the invention are useful, for example, as the principal film forming binders in g compositions. Advantageously, these compositions can be formulated without additional plasticisers or coalescing solvents, as the glass transition temperatures of the esters allow for film formation at ambient temperatures.

Thus, the cellulose mixed esters of the invention are particularly useful in coating compositions such as paint, especially waterborne formulations such as low VOC paint formulations.

The invention therefore relates to coating compositions comprising the cellulose mixed esters of the invention. Typically, such compositions will e one or more cellulose mixed esters of the invention, together with one or more suitable ts, such as organic solvents and water, e.g. polar organic solvents. Suitable solvents e, but are not limited to, ketones, esters, glycol ethers, alkyl pyrrolidones, DMSO and other polar and/or oxygenated solvents known to those skilled in the art. The inclusion of water at le levels in the composition affords a dispersion of the invention le for formulation of waterborne coatings.

A typical coating ition comprises about 10% to about 60% by weight, preferably about % to about 50% by weight, e.g. about 28% or about 43% by weight of the one or more cellulose mixed esters of the invention. A solventborne coating ition may also comprise from about 20% to about 50% by weight, ably about 30% to about 40% by weight, e.g. about 33% by weight or about 34.5% by weight of a suitable solvent. Other ves may also be present. For example, a l paint composition may also include titanium dioxide, e.g. about 20% to about 30% by weight, ably 21% to 23% by weight.

A solventborne gloss paint composition comprising one or more cellulose mixed esters of the invention will typically comprise, as t, a mixture of ethyl e, butyl acetate, N-methyl- 2-pyrrolidone (NMP), cyclohexanone and/or methyl dibasic esters (e.g. dimethyl adipate, dimethyl glutarate and dimethyl succinate (approximately 17:66:17 % by mass). A waterborne gloss paint composition comprising one or more cellulose mixed esters of the invention will typically comprise a dispersion of the cellulose mixed ester in water and ally a suitable co- solvent such as a polar organic solvent. Suitable polar organic ts include, but are not limited to, ketones, esters, glycol ethers, alkyl pyrrolidones, DMSO and other polar and/or oxygenated solvents known to those skilled in the art. Optionally one or more other additives such as surface wetters, levelling agents, waxes, silicones, biocides, de-foamers, anticorrosive pigments, UV absorbers and rheology modifiers may be added to both solventborne or orne compositions. In one embodiment, a paint composition comprising one or more cellulose mixed esters of the invention also ses a 50:50 mixture of cyclohexanone and methyl dibasic esters (dimethyl adipate, dimethyl glutarate and dimethyl succinate (approximately 17 % by mass», titanium dioxide, bentonite clay and soya lecithin. In another embodiment, a paint ition comprising one or more cellulose mixed esters of the invention also comprises water, titanium e, anionic dispersants and antimicrobial agents.

Other gloss paint compositions may be produced through dissolution or dispersion of one or more cellulose mixed esters of the invention in a suitable solvent(s), ed by addition of universal tinters. One or more additives such as surface wetters, levelling agents, waxes, silicones, biocides, de-foamers, anticorrosive pigments, UV absorbers and rheology modifiers can be incorporated to enhance or improve specific properties.

In addition, modification through blending with other film-forming polymers is possible.

Gloss can be reduced through incorporation of extender pigments including silica, alkali/alkaline earth metal silicates, calcium carbonate, kaolin, mica and talc as known to those skilled in the art of paint formulation.

In another embodiment, a paint composition comprising one or more cellulose mixed esters of the invention also comprises a 50:50 mixture of cyclohexanone and methyl dibasic esters (dimethyl adipate, dimethyl glutarate and dimethyl succinate (approximately 17 % by mass)), titanium dioxide, ite clay, soya lecithin and nepheline syenite.

A coating composition comprising one more cellulose mixed esters of the ion can be used to coat a variety of substrates, for example wood, metal, pre-coated substrates, plastics and glass. The invention therefore further relates to a coated substrate which is coated with a coating composition comprising one or more ose mixed esters of the invention. Such ates can include wood, metal, ated substrates, plastics and glass.

General Synthetic s The cellulose-levulinyl mixed esters of the invention can be prepared according to the following general methods. Those skilled in the art will iate that cellulose can be obtained from a variety of sources such as wood pulp, cotton linters, recycled cellulosic materials such as paper and cardboard or vegetable fibres such as corn fibre.

Step 3) - Swelling Cellulose (e.g. microcrystalline cellulose, mechanical or Kraft wood pulp) is stirred in warm water for 2-4 h and then filtered. This process is repeated if ary. The swollen cellulose is then stirred in warm acetic acid for 1-4 hours and filtered and this process is repeated. This cellulose is used for the preparation of mixed esters in which the degree of substitution of levulinyl is less than approximately 1.5 levulinyl units per oglucose unit (D.ev < 1.5). For preparation of esters with higher levulinyl substitution the acetic acid wet cellulose is stirred in warm levulinic acid and filtered, and then this process is repeated. For preparation of esters that do not include acetate functionality the acetic acid wet cellulose is stirred with either warm levulinic acid, or the relevant acid, and filtered, and then this process is repeated.

Step b) - Reaction Swollen cellulose is added to a solution of alkyl anhydride, (6-12 eq per anhydroglucose unit), levulinic acid (9-18 eq) and sulfuric acid (15-45 meq) (alternatively, methanesulfonic acid or para-toluenesulfonic acid can be used) and the mixture is heated to 120 °C for 4-24 hours.

Alternative order of addition can be completed. For example a reaction mixture of alkyl ide, levulinic acid and sulfuric acid can be prepared before charging the cellulose to the reaction. This permits moderation of any exotherm from combination of the reagents. Those skilled in the art will appreciate that the choice of alkyl anhydride will depend on the d C2- 06 acyl group. For example, acetic anhydride is used to prepare cellulose mixed esters comprising an acetyl group, and propionic anhydride is used to prepare ose mixed esters comprising a propionyl group.

Alternative Step b) -— Reaction Using Chlorinated Solvent A reaction mixture is prepared that contains alkyl anhydride (0.7 parts, 28 g), levulinic acid (1 part, 40 g), sulfuric acid (1.55 x 10'6 parts, conc, 62 uL) and a chlorinated solvent such as 1,2- dichloroethane (1.33 parts, DCE, 53 9). Those skilled in the art will appreciate that the choice of alkyl anhydride will depend on the d CQ-Cs acyl group. For e, acetic anhydride is used to prepare cellulose mixed esters sing an acetyl group, and propionic anhydride is used to prepare ose mixed esters comprising a propionyl group. Swollen cellulose (1.24 g cellulose, 4 g AcOH—wet cellulose) is reacted with 40.6 g of the reaction mixture solution (4 eq ide). The on mixture is heated with stirring to reflux and after 60 minutes the solution is cooled. The chlorinated solvent is evaporated before Step 0).

Step 0) - Work up The cooled reaction mixture is diluted with a solution of magnesium or sodium acetate or sodium bicarbonate (0.4 eq) in water (50-100 eq) and acetic acid (15-30 eq). This mixture is poured into water (5-20 volumes) and stirred vigorously for 1-4 hours. The precipitate is filtered, washed twice with water and dried to give the levulinyl cellulose mixed ester. If necessary the wet material can be further purified by dissolution in a suitable solvent, e.g. acetone (alternatively, N-methylpyrrolidine can be used), and cipitation into water.

Alternative Step 0) - Work up of Chlorinated Solvent Reaction The crude product is diluted with an acidified aqueous solution containing Mg(OAc)2 then poured into a 20% ethanol in water solution. After filtration the product is washed with 20% ethanol in water.

The ose-levulinyl mixed esters of the invention lly have weight average molecular weights (Mw) (when deacylated) of about 4000 to about 11000. The molecular weights of the cellulose—levulinyl mixed esters can be determined by high performance size exclusion chromatography coupled with multi-angle laser light scattering (SEC — MALLS) or refractive index detection (SEC-RI). lly the degree of polymerisation of the cellulose-levulinyl mixed esters is about 20 to about 70 but can vary from about 2 to about 3500.

The above general reaction conditions can be used to produce cellulose-levulinyl mixed esters with a total degree of substitution per anhydroglucose (D5) of about 2.8 to about 3.4, a degree of tution per anhydroglucose of nyl groups (Dlev) of about 0.2 to about 2.6, a degree of substitution per anhydroglucose of Cz-Ce acyl groups (DAcw) of about 0.5 to about 2.8 and a WO 85397 degree of substitution per anhydroglucose of hydroxyl groups (DOH) of 0 to about 0.5 which, when deacylated, have weight e molecular weights (MW) of about 5400 to about 11000 and degrees of risation, (D,,) of about 30 to about 70.

Advantageousiy, these cellulose-levulinyl mixed esters, e.g. the mixed ester LAC-1 described in Example 1, can be further manipulated by chemical modification of the carbonyl group of the nyl moiety. For example, levulinyl cellulose mixed esters can be reacted with an aryloxyamine such as benzyloxyamine or an alkoxyamine of general formula RZ-O-NHZ, or with an acyl ide of a R3-C(=O)-NH-NH2, where R2 and R3 are as defined above.

Typically, the levulinyl ose mixed ester, e.g. the mixed ester LAC-1, is dissolved in a suitable solvent such as chloromethane or ethyl acetate and the solution is contacted with an yamine or an alkoxyamine (RZ-O-NHZ) or an acyl hydrazide (Rz-C(=O)-NH-NH2) and a suitable acid such as acetic acid. Suitable aryloxyamines, alkoxyamines and acyl hydrazides are described in the Examples section. The reaction is stirred, e.g. at room ature, and monitored, for example by TLC, to determine when all of the aryloxyamine, alkoxyamine or acyl hydrazide has reacted. The reaction mixture is readily worked up by evaporation of the solvent to give the desired levulinyl oxime or a levulinyl acyl hydrazide mixed ester.

Definitions The term “degree of polymerisation" refers to the number of anhydroglucose units that are 01-4 linked in the cellulosic polymer chain.

The term “degree of substitution” refers to the level to which the three alcohol sites on the cellulosic polymer are substituted with ester functionality. Those skilled in the art will understand that, for short r chains, the total degree of substitution can rise above three due to end group contribution.

The term “residual hydroxyl functionality per anhydroglucose unit” refers to the number of hydroxyl groups per anhydroglucose unit of the osic polymer.

The term “alkyl” means any saturated hydrocarbon radical having up to 30 carbon atoms and includes any , C1-C20, C1-C15, C1-C1o, or C1-C5 alkyl group, and is intended to include both straight- and branched-chain alkyl groups, and to exclude cyclic alkyl groups. Examples of alkyl groups include: methyl group, ethyl group, n-propyl group, iso-propyl group, l group, iso- butyl group, sec-butyl group, t-butyl group, n-pentyl group, 1,1-dimethylpropyl group, 1,2- dimethylpropyl group, 2,2-dimethylpropyl group, 1-ethylpropyl group, 2—ethylpropyl group, n- hexyl group and 1-methylethylpropyl group.

The term “alkylene” means any ted hydrocarbon radical having up to 30 carbon atoms and includes any 01-025, 01-020, , 01-010, or C1-Ce alkylene group, and is intended to include both straight- and branched-chain alkylene . Examples of alkylene groups include: methylene ) group, ethylene [(-CH2-)2] group, n-propylene [(-CH2-)3] group, iso- propylene group, lene group, iso-butylene group, sec-butylene group, t-butylene group, npentylene group, 1,1-dimethylpropylene group, 1,2-dimethylpropylene group, 2.2- dlmethylpropylene group, 1-ethylpropylene group, 2-ethylpropylene group, n—hexylene group and 1—methyl—2—ethylpropylene group.

The term “C2-C5 acyl” means R”-C(=O) where R” is a C1-C5 alkyl group. In the cellulose mixed esters of the invention the acyl groups are connected via their carbonyl carbon atoms to oxygen atoms on anhydroglucose moieties of the cellulose.

The term “levulinyl" means a radical of formula: 0 . in the cellulose mixed esters of the invention that comprise levulinyl ester groups, levulinyl groups are connected where shown ( W )to oxygen atoms on oglucose moieties of the cellulose.

The term “carboxy” means a radical of formula: 1,1... . In the cellulose mixed esters of the invention that comprise y groups, the carboxy groups may be connected where shown ( W ) to an alkylene moiety to form groups such as boxy: , for example, EUR... , wherein z is a lkylene and wherein alkylene is defined as above and ( W )is the point of attachment.

Any alkyl group may optionally be substituted with one or more tuents selected from the group consisting of moieties not labile to the esterification process such as, but not limited to, halogen, cycloalkyl groups, aryl groups, straight or branched chain alkenyl groups, straight or branched chain alkynyl groups, each of which may optionally be substituted with one or more halogen atoms.

The term en" means fluorine, chlorine, iodine or bromine.

BRIEF DESCRIPTION OF THE FIGURES Figure 1 shows the 1H NMR spectra of LAC-1 (1c), oxime 3b (1b) and LAC-3b-2 (1a).

Figure 2 shows the 1H NMR spectra of LAC-3a-1 (23) and LAC-3a-2 (2b).

Figure 3 shows the 1H NMR a of LAC-30—1 (3a) and LAC-3c—2 (3b).

Figure 4 shows the 1H NMR spectra of LAC-3f—‘l (4c), LAC-3f-2 (4d), LAC1 (4a) and LAC2 (4b).

Figure 5 shows the 1H NMR spectrum (CDCI3) for a cellulose-acetyl-levuIinyl-lactone mixed ester, the on product of pre-swelled cellulose with levulinic acid, acetic anhydride, sulfuric acid and 1,2-dichloroethane for a minimum reaction time to effect dissolution, showing the presence of species (7). The substitution pattern is non-exact but representative of the overall composition and relevant 1H NMR spectrum.

ABBREVIATIONS AcOH acetic acid AGU anhydroglucose unit BP boiling point.

CAB cellulose e butyrate CDCI3 deuterochloroform DAc degree of acyl substitution DLev degree of nyl substitution Dp degree of polymerisation DS degree of substitution DTot total degree of substitution DCE 1,2-dichloroethane DCM methylene chloride DSC differential scanning metry DMA dimethylacetamide DMSO dimethylsulfoxide ESI ospray ionisation FTIR Fourier transform infrared HPLC high performance liquid chromatography LevOH or Lev levulinic acid MS mass spectrometry Mn number average molecular weight Mw mass e lar weight NMP n-methylpyrrolidine NMR nuclear magnetic resonance Rl refractive index OTf Triflate SEC-MALLS size exclusion chromatography—multi angle laser light scattering Tg glass transition temperature TLC thin layer chromatography TMS tetramethylsilane UVNis ultraviolet / visible VOC volatile organic compound EXAMPLES The following examples further illustrate the invention. It is to be appreciated that the invention is not d to the examples.

General Procedures NMR spectra are collected for 1H and 13C at 500 and 125 MHz respectively and are in CDCI3 unless otherwise stated. Chemical shifts are in ppm from TMS. Degree of substitution (D5) and degree of levulinyl substitution (DIev) are ated from 1H NMR integrals. Glass transition temperatures (T9) are measured by differential scanning calorimetry (DSC). Samples are prepared by compressing 2-20 mg of material into a 40uL pierced aluminium pan and are d between -40° and +180° C at either 10°C/min or 5°C/min. The samples are heated and cooled three times and T9 data are obtained from the second and third sweep; ignoring the initial ing and de-solvating sweep. T9 are ined by observation of the rate of change of slope and baseline shift for the glass and plastic states. Molecular weight is determined by comparison of retention times to polystyrene standards using high performance size exclusion chromatography (HPLC-SEC) d with a Dawn EOS multi-angle laser light scattering (SEC—MALLS) by Wyatt Technology to confirm molecular weights of samples. Chromatography is completed on a Waters Alliance 2690 HPLC coupled to a Waters 2410 Refractive index (RI) or and Waters 490E multi wavelength Ultraviolet e spectrometer (UV/Vis). A series of polystyrene standards (Tosoh Corporation, Cat 06476) are injected and the retention volume plotted against the published Mw values. The plot of retention volume versus log Mw can be imated by a third order polynomial of R-squared value better than 0.998. Comparison of the retention volume for the peak maxima for the cellulose ester tives permits calculation 2012/000228 of the lar weight in comparison to polystyrene standards. The cellulose mixed ester (~ 10 mg) is dissolved in dimethylacetamide (1 mL) and clarified by centrifugation. An aliquot (10 pL) is ed onto a column system comprising the following Tosoh Corporation columns: Guard column (Super H-H, Cat 18003, 50 x 4.6 mm) in series with TSK-Gel Super HM-H and HM-L columns (150 x 6 mm, Cat 18001 and . The system ed with flow rate 0.25 mL min’1 and temperature 60 °C in dimethylacetamide (DMA). Peaks are detected with a refractive index To t Mw calculations cellulose mixed esters are also treated with base to hydrolyse the ester groups and the residual cellulose oligomer mixture analysed directly by SEC-MALLS.

Cellulose ester (approx 60 mg) is dissolved in dioxane (4 mL) and methanolic NaOMe (5M, 1 mL) at 50°C. After 15 min water (8 mL) is added and the suspension is heated at 50°C for a further 15 min. The cooled suspension is centrifuged and the pellet washed with water and dried. A portion of this material (10 mg) was dissolved in dimethylacetamide — LiCl,(8 % w/v, 1 mL) and clarified by centrifugation. Analysis, on the column system described above, operating with a mobile phase of 0.5% w/v LiCl / DMA was completed. Data for molecular weight ination are analysed using ASTRA software (Version 4.73.04) using a dn/a’c of 0.104 mL 9'1 (Refractive Index Data-book for Polymer and Biomolecular Scientists, A. , C. Johann, M.P. Deacon and SE. g, Nottingham University Press, (1999) ISBN 129- 8reference).

Example 1: Preparation of a LevulinyI-acetyl Ester of Cellulose (LAC-1).

Example 1.1 Wood pulp (pinus, bleached, medium coarse, 16 g) is soaked in warm water (200 mL) and then filtered. The resulting damp, swelled cellulose is soaked in acetic acid (200 mL) at 40° for 90 min. Excess acid is removed by filtration and the cellulose is again soaked in acetic acid and filtered. Levulinic acid (97 g) and acetic anhydride (84 ml) are mixed and sulfuric acid (0.11 ml) is added. This mixture is added to the cellulose and the whole heated at 120°C for 6h. A mixture of NaHC03 solution (10 mL, 10% aqueous) and acetic acid (10 mL) is added to the reaction mixture and then the whole is poured slowly into water (4 L) with ng. The precipitate is isolated by filtration. This material is dissolved in acetone (550 mL) and re-precipitated in water (3 L). The resulting light brown solid is ed by filtration. Residual solvents are removed at 45°C and 15 mm Hg to give LAC-1 (29 g). (DS 3.1 esters per anhydroglucose unit (AGU), Dlev 0.82. Tg 97°C. 1H NMR spectrum is shown in Figure 1. MW11800, DP 35.

Example 1.2: Preparation of a LevulinyI-acetyl Ester of Cellulose at the 500 9 scale Wood pulp (pinus, bleached, medium coarse, 500 g) is twice pre-soaked in water and then twice in acetic acid to give a wet cake comprising acetic acid (1.15 kg) and cellulose (0.5 kg).

Levulinic acid (4.49 kg) is d to a jacketed glass reaction vessel heated to 35 °C. Sulfuric acid (3.5 mL) is charged to the vessel followed by the slow addition of acetic anhydride (2.835 kg) to ensure the exotherm does not raise the temperature above 60 °C. The cellulose wet cake is charged to the reaction vessel and the jacket heated to 120 °C. The reaction heating is continued with stirring for 4.8 hours and then the on is cooled to 30 °C over the period of minutes. A solution of Mg(OAc)2 (0.25 kg) and acetic acid (3.13 kg) with water (3.15 L) is ed and d to the reaction mixture with ng for 15 hr. The reaction mixture is split into two approximately equal portions and each itated with water (37.5 L). The precipitates are recombined by sequential recovery on a polypropylene filter membrane (54 micron) in a filter drier. The filtrate is washed three times with water (15, 15 and '20 kg). The al is recovered and dried in a vacuum oven to recover the crude cellulose mixed ester (890.71 9). A portion (287.3 g) is further purified by dissolution in acetone (1 L) and precipitated into water (25 L). The itate was recovered on a filter paper (Advantec 2), slurried with water (12.5 L) and stirred (1.5 hr) before filtration and the filtrate plug-washed with water (3.5 L).

The resulting light brown filtrate is dried and residual solvent removed at 45°C and 15 mm Hg (48 hr) to give the final product (253.3 9). (DS 3.15 esters per anhydroglucose unit (AGU), D.ev 1.22. T9103.4 °C. MW 9970, DP 27.

Example 1.3 Pre-swelled wood pulp (29.3% w/w ose with acetic acid) is washed with nic acid to generate a levulinic acid swelled cellulose (31.2 % w/w cellulose with nic acid).

A reaction mixture is ed that contains acetic anhydride (3 eq per OH, 5.67 g, 55.5 mmol), LevOH (1.33 eq to ACQO, 8.6 g) and sulfuric acid (conc, 7.15 uL). To this solution is charged the pre-swelled cellulose (1 g cellulose, 3.21 g levulinic-wet cellulose). The reaction mixture .is heated to 120 °C for 2 hr. The reaction is cooled, diluted with dope solution (15 mL, 1:1 AcOH to water containing 10% w/w Mg(OAc)2) and stirred. The clear solution is poured into rapidly mixed water (300 mL) and the resultant pale yellow precipitate is filtered (Advantec 1). Two repeat washings with water (150 mL) generate the final product that was dried ght at 50 °C: By 1H NMR Dm 3.05, DLev 1.20, DAc 1.85. T9 108 °C.

Example 1.4 Preparation of a Levulinyl-acetyl Ester of Cellulose using microwave energy Cellulose 1.64 g (0.25 g, 1.5 mmol AGU, 4.5 mmol OH; dry weight pre-swelled in acetic acid) was mixed with acetic anhydride (1.31 g, 12.8 mmol), levulinic acid (1.96 g, 16.9 mmol) and sulfuric acid (2 uL). The reaction mixture was treated to microwave energy for 10 minutes using 60W with a maximum reaction temperature set to 130°C. After this period the clear brown solution was diluted (2 mL, 1:1 AcOH to water containing 10% w/w )2) poured into ~45 mL of water with vigorous stirring and the resultant precipitate was collected by centrifugation.

The precipitate was washed twice with water and oven dried overnight (50°C) to give an off- white solid LAC: By 1H NMR Dm 3.5, DLG,v 0.7, DAc 2.8, T9 103°C, Mw 7600.

Example 2: Preparation of a Levulinyl-propionyl Ester of Cellulose The reaction is carried out in a r fashion to Example 1.2 above except the reaction mixture contains propionic ide (3 eq per OH, 7.23 g, 55.5 mmol) instead of acetic anhydride and sulfuric acid (conc, 8.85 uL). An cal reaction and workup procedure is used, except the dope solution is poured into 600 mL of water to deliver the product: By 1H NMR Dm 3.07, DLeV 1.84, mep 1.23. T9 76 ”C.

Example 3: Preparation of a Levulinyl-isobutyryl Ester of Cellulose The reaction is carried out in a similar fashion to Example 1.2 above except the reaction mixture contains isobutyric anhydride (3 eq per OH, 8.79 g, 55.5 mmol) instead of acetic anhydride and sulfuric acid (conc, 9.2 uL). An identical reaction and workup procedure is used, except the dope solution is poured into 1200 mL of water to deliver the product: By 1H NMR DTm 3.04, DLeV 2.45, Dlsogm 0.59. Tg 62°C.

Example 4: Preparation of a Levulinyl-butyryl Ester of Cellulose The reaction is d out in a similar fashion to e 1.2 above except the reaction mixture contains butyric anhydride (3 eq per OH, 8.79 g, 55.5 mmol) instead of acetic anhydride and sulfuric acid (conc, 8.95 uL). An cal reaction and workup ure is used, except the dope solution is poured into 1200 mL of water to deliver the t: By NMR Dm 2.93, DLeV 1.80, Dem 1.13. T961°C.

Example 4a: Preparation of a LevulinyI-butyl-acetyl Ester of Cellulose In a similar fashion to e 1.3 a reaction mixture was ed excepting that the acetic acid pre-swelled cellulose was treated with butyric anhydride (3 eq) and the catalyst sulfuric acid was replaced with aluminium triflate (Al(OTf)3, 0.08 mol% compared to hydroxyl). The reaction was permitted to proceed for 30 minutes at 120°C and worked up in a similar fashion to produce BLAC as an off-white solid: By NMR DTot 3.3, DLeV 1.9, D3,, 1.1, DAc 0.3, T9 63°C, MW 12,000.

Example 4b: Preparation of a nyl-butyI-acetyl Ester of Cellulose in a similar fashion to example 4a, a reaction mixture was prepared ing that the catalyst was aluminium te (Al(OTf)3, 3.3 mol% compared to hydroxyl, 10 mol% compared to AGU).

The reaction was permitted to proceed for 15 minutes at 83°C and worked up in a similar fashion to produce BLAC as a white solid: By NMR DTOt 3.2, Om 1.6, DBu 0.5, DAc 1.1, Tg 103°C, MW 26,000.

Example 4c: Preparation of a Levulinyl-butyl-acetyl Ester of Cellulose in a similar fashion to e 4a, a reaction mixture was ed ing that the catalyst was ytterbium triflate f)3 and H3P04, both at 0.8 mol% compared to hydroxyl, 10 mol% compared to AGU). The reaction was permitted to proceed for 60 s at 83°C and worked up in a similar fashion to produce BLAC as a white solid: By NMR Om 2.9, DLev 1.9, D8,, 0.8, DAc 0.1, T9 80°C, MW 17,000.

Example 5: Preparation of a Levulinyl-valeryl Ester of Cellulose The reaction is carried out in a similar fashion to Example 1.2 above except the reaction mixture contains valeric anhydride (3 eq per OH, 10.35 g, 55.5 mmol) instead of acetic anhydride and sulfuric acid (conc, 9.9 uL). An identical reaction and workup procedure is used, except the dope solution is poured into 500 mL of water, generating an oiled-out product. The water is decanted and the sticky material triturated with water (500 mL, 40 °C). The polymer begins to harden with this treatment and an additional 500 mL trituration at room temperature with vigorous stirring for 16 hr is completed. Re—precipitation from acetone (~35 mL acetone poured into 450 mL of water) delivers the product the product after overnight drying at 50 °C: By NMR Dm 3.13, DLeV 2.03, DVa. 1.1. T9 45 °C.

Example 6: Preparation of a LevulinyI-hexanoyl Ester of Cellulose The reaction is carried out in a similar fashion to Example 1.2 above except the reaction mixture contains hexanoic anhydride (3 eq per OH, 11.9 g, 55.5 mmol) instead of acetic anhydride and sulfuric acid (conc, 10.8 uL). An identical on and workup procedure is used, except the dope on is poured into 500 mL of water generating soft amorphous solid. The water is decanted and the sticky material triturated with water (500 mL, 40 °C). The polymer is dispersed into a 45 °C 1:1 mixture of methanol and isopropanol and upon g to 0 °C the polymer is red from the solution with filtration. cipitation from acetone (~35 mL acetone poured into 16.6% aqueous AcOH (400 mL)). The solid is re-washed with 16.6% aqueous AcOH (200 mL), 8.3% aqueous AcOH (200 mL) and finally water (200 mL). The product is dried overnight at 50 °C : By NMR Dm 2.95, DLeV 2.04, DHex 0.91. T9 54 °C.

Example 7: Alternative Methods for the Preparation of a nyl-acetyl Ester of Cellulose lvent Reaction ses) Example 7.1 Pre-swelled cellulose (5 g cellulose, 16.1 g AcOH-wet ose) is stirred and heated to reflux with acetic anhydride (45 g), LevOH (65 g), ic acid (conc, 100 uL) and dichloromethane (DCM, 60 mL). After 16 hr the reaction is halted, the chlorinated solvent evaporated and the reaction diluted with 10% aqueous Mg(OAc)2 solution (10 mL) before pouring into a stirred 20% ethanol/water solution (100 mL). The solid formed is recovered by filtration and twice washed with ethanol before drying overnight at 50 °C: By NMR D701 2.9, DLev 0.9, DLacwne 0.86. T9 137 °C. NMR (CDCI3) refer Figure 6; 8 1H ppm 1.55 brds Cﬂg-Iactone, 1.65 brds Cﬂg-lactone, 1.80- 2.25 multiple brds, Cﬂ;—C=O, .00 brdm Lev CﬂgCH , 3.20-5.40 m cellulose Cﬂ, 6.20 reducing end ic Cﬂ; 5 13C ppm (all broad multiplets) 20.7 Ac, 20.8 Ac, 23.1 Iactone CH3, .1 lactone CH3, 27.8 Lev CH2, 28.9 lactone CH2, 29.7 Lev CH3, 34.5 Iactone CH2, 37.6 Lev CH2, 60.5 cell-CH2, 62.3 cell-CH2, 72-77 cell-CH, 100.1, anomeric CH, 109.4 lactone C, 169- 172 ester, 175.7 lactone, 206.2 Lev C=O.

Example 7.2 A reaction mixture is prepared that contains acetic anhydride (28 g), LevOH (40 g), ic acid (conc, 62 uL) and 1,2-dichloroethane (DCE, 53 g). Pre-swelled ose (1.24 g cellulose, 4 g AcOH-wet cellulose) is reacted with 40.6 g of the reaction mixture solution. The on mixture is heated with stirring to reflux and after 60 minutes the clear orange solution is cooled.

Evaporation of the chlorinated solvent and dilution with 30 mL of an acidified aqueous solution containing )2 then pouring into a 20% l in water (60 mL) solution permits the recovery of a pale yellow product by filtration. Washing twice with 20% ethanol in water and filtration followed by ght drying at 50 °C gives an off-white solid (1.70 9): By NMR DTot 3.3, DLev 1.15, DLamone 0.43. T9114 °C.

Example 7.3 A reaction mixture is prepared that contains acetic anhydride (567 g, 5.55 mol, 3 eq per OH), LevOH (810 g, 6.97 mol), ic acid (conc, 126 uL) and 1,2-dichloroethane (DCE, 729 9). To this solution is charged pre-swelled cellulose (100 g cellulose, 326 g AcOH-wet cellulose). The reaction mixture is heated without stirring to reflux and after 5 hours the solution is cooled.

Evaporation of the chlorinated solvent and dilution with 3.79 kg of an acidified aqueous solution containing Mg(OAc)2 then pouring into a 20% ethanol in water solution (5 L) permits the recovery of a pale yellow product by filtration. Washing twice with 20% ethanol in water and tion followed by overnight drying at 50 °C gives an off-white solid (154.3 g, 69%): By NMR DTot 3.06, DLev 1.30, DLacmne <0.2, T9 87 °C.

Example 8: Preparation of Alkoxyamines (3) ——>aor b ROH RO-N>© ——»c RONH2 1 2 3 a R=CH3(OCHQCH2)2 b R=CH3(OCHZCH2)3 C OCH20H2)5_11 d R=n-CBH17 f R=benzy| Scheme 1 ts: a) MsCI, Et3N, CHZCIZ; then N-hydroxyphthalimide, diisopropylethylamine , DMF, 90°C. b) N-hydroxyphthalimide, ropylazodicarboxylate, Ph3P, THF; c) hydrazine hydrate, MeOH or EtOH.

Step 1 - Preparation ofAlkoxyphthalimides 2 A solution of a monomethyl ethylene glycol 1a-d (16-60 mmol) in CH2CI2 (dry, 10-120 mL) with methansulfonic chloride (1.1 eq) is cooled in an ice-water bath whilst Eth (1.6 eq) is added slowly. On completion of the addition the mixture is stirred at room temperature for 1h. Salts are removed by filtration and the filtrate concentrated to dryness. The residue is taken up in EtOAc and extracted twice with water. The EtOAc solution is dried and concentrated. The resulting mesylate, N-hydroxyphthalimide (1.1 eq) and diisopropylethylamine (1.05 eq) are ved in DMF (50-100 mL) and heated at 90°C for 6h. After g the solvent is evaporated and the residue partitioned between EtOAc and NaZCO3 (10% aqueous). The EtOAc solution is washed with further Na2C03 solution and with water; dried, and concentrated to give the phthalimides 2. 2-(2-(2-Methoxyethoxy)ethoxy)isoindoline-1,3-dione 2a Diethylene glycol monomethyl ether 1a (29, 16.7 mmol) gives alkoxyphthalimide 2a (3.6 g, 82%) as a brownish oil. 1H NMR 6 7.84 (m, 2H), 7.75 (m, 2H), 4.39 (m, 2H), 3.88 (m, 2H), 3.67 (m, 2012/000228 4H), 3.48 (m, 2H), 3.29 (s, 3H). 13C NMR 5163.3, ,134.4, 129.0, 123.5 (all 2C), 77.2, 71.8, 70.7, 69.4, 58.9. ESI - MS calc. for C13H15N05Na [M+Na]+ 288.0848, found 288.0846. 2-(2-(2-(2-Methoxyethoxy)ethoxy)ethoxy)isoindoline-1,3-dione 2b Triethylene glycol monomethylether 2a (5.2 g, 31.7 mmol) gives alkoxyphthalimide 2b (7.4 g, 75%) as a pale brown waxy solid. Mp (EtOAc — hexanes) 40 — 41°. 1H NMR 8 7.85 (m, 2H), 7.76 (m, 2H), 4.38 (m, 2H), 3.87 (m, 2H), 3.57 (m, 2H), 3.58 (m, 4H), 3.50 (m, 2H), 3.35 (s, 3H). 130 NMR 8163.4, 134.4, 129.0, 123.4 (2C each), 77.2, 71.8, 70.8, 70.5, 70.5, 69.2, 59.0. ESI - MS calc. for C15H19N05Na [M+Na]+ 332.110, found 332.1119.

Methoxypolyethoxyisoindoline-1,3-dione 2c Polyethylene glycol monomethyl ether, MW 350 1c (20 g, 58.8 mmol) gives alkoxy-phthalimide 2c (18.9 g, 66%). 1H NMR 8 7.84 (m, 2H), 7.75 (m, 2H), 4.38 (m, 2H), 3.69 — 3.52 (bm, poly H), 3.34 (s, 3H). 13C NMR 8163.2, 134.3, 128.8, 123.3 (all 20), 77.0, 71.8, 70.6, 70.4 (poly C), 69.2, 58.8. MS calc. for C21H31N09Na [M+Na]+ 464.1897, found 464.1892; calc. for C23H35NO1oNa [M+Na]+ 508.2159, found 508.2154; calc. for CZ5H39NO11Na [M+Na]+ 21, found 552.2418; calc. for C27H43NO12Na + 596.2683, found 596.2682. 2-(Octyloxy)isoindoline-1,3-dione 2d n—Octanol 1d (1 g, 7.7 mmol) gave alkoxyphthalimide 2d (1.0 g, 47%) as white plates, mp 51- 52°. 1H NMR 8 7.84 (m, 2H), 7.74 (m, 2H), 4.20 (t, J= 6.8 Hz, 2H), 1.79 (m, 2H), 1.48 (m, 2H), 1.39 — 1.25 (bm, 8H), 0.88 (t, J = 6.9 Hz, 3H). 13C NMR 8i] 163.7, 134.5, 129.1, 123.6 (2C each), 78.7, 31.9, 29.4, 29.3, 28.3, 25.6, 22.7, 14.2. ESI - MS calc. for C16H21N03Na [M+Na]" 298.1419, found 298.1423.

Step 2- Preparation ofAlkoxyamines 3 A solution of phthalimide 2a-d (3.8 - 16 mmol) in methanol or ethanol (10 - 50 mL) is cooled in an ice-water bath whilst hydrazine hydrate (51%, 1.3 eq) is added. The solution is then stirred at room temperature for 1h, filtered and concentrated under reduced pressure. The residue is dissolved in water (20-30 mL) and ted twice with EtOAc (10 mL). The aqueous phase is concentrated to give the title nes 3a-c as pale yellow oils.

O—(2-(2-Methoxyethoxy)ethyl) ylamine 3a Hydroxyphthalimide 2a (19, 3.8 mmol) gave hydroxylamine 3a (0.30 g, 59%). 1H NMR 8 5.37 (bs, 2H), 3.84 (m, 2H), 3.67 (m, 4H), 3.56 (m, 2H), 3.38 (s, 3H). 13C NMR 5 74.7, 71.9, 70.4, 69.5, 58.9. ESI — MS Calc for 03 [M+H]+ 136.0974, found 136.0973.

O-(2-(2-(2-Methoxyethoxy)ethoxy)ethyl)hydroxylamine 3b Hydroxyphthalimide 2b (5.09, 16.3 mmol) gives hydroxylamine 3b (1.4 g, 48%). 1H NMR 5 5.49 (bs, 2H), 3.84 (m, 2H), 3.67 (m, 2H), 3.56 (m, 2H), 3.38 (s, 3H). 13C NMR 5 74.8, 72.0, 70.6, 70.5 (2C), 69.6, 59.0. ESI-MS calc. for C7H15NO4 [M+H]+ 180.1236, found 180.1239.

Methoxypolyethoxyethylhydroxylamine 3c Hydroxyphthalimide 2c (3.09, 6.2 mmol) gives hydroxylamine 3c (1.1 g, 50%). 1H NMR 5 5.48 (bs, 2H), 3.83 (m, 2H), 3.74 — 3.62 (bm, poly H), 3.55 (m, 2H), 3.38 (s, 3H). 13C NMR 5 74.6, 71.8, 70.4, 69.4, 58.8. ESI-MS calc. for N08 [M+H]+ 356.2285, found 356.2275; calc. for N09 [M+H]+ 400.2547, found 400.2540; calc. for C19H42NO10 [M+H]+ 444.2809, found 444.2802; calc. for C21H46NO11 [M+H]+ 488.3071, found 69. lhydroxylamine 3d , Hydroxyphthalimide 2d (0.45 g, 1.6 mmol) gave hydroxylamine 3d (0.19 g, 80%). 1H NMR 5 .34 (bs, 2H), 3.65 (t, J = 6.9 Hz, 2H), 1.57 (m, 2H), 1.35 — 1.23 (bm, 10H), 0.88 (t, J = 6.8 Hz, 3H). 13C NMR 5 76.3, 31.8, 29.5, 29.3, 28.4, 26.0, 22.7, 14.1. ESI - MS calc. for CBHZONO [M+H]+ 146.1545, found 146.1528.

Example 9: Preparation of Acyl Hydrazides (5) \O/\/0\/\OH a ———-—) \O/\/O\/\O/\/U\O/\ _—_..

\O/\/0\/\O/\/U\E’NH2 Scheme 2 Reagents: a) Ethyl acrylate, NaH (cat), THF; b) Hydrazine hydrate.

Ethyl 3-(2-(2-methoxyethoxy)ethoxy)propanoate 4 Sodium e (60%, 0.034 g, 0.02) is suspended in THF (10 mL) and diethylene glycol monomethyl ether (5.00 ml, 42.4 mmol) is added with ice cooling. Ethyl acrylate (4.71 ml, 1.02 eq) is added and the solution stirred at room temperature for 2h. Acetic acid (0.049 ml, 0.849 mmol) is added and the solution concentrated. The residue is taken up in EtOAc (20 mL) and washed with water. The organic phase is dried and evaporated to give a clear liquid which is puriﬁed by distillation (1200, 0.3 torr), 4, 5.2 g, 56%. 1H NMR 5 4.15 (q, J = 7.4 Hz, 2H), 3.76 (t, J = 6.5 Hz, 2H), 3.63 (m, 6H), 3.54 (m, 2H), 3.38 (m, 3H), 2.59 (t, J = 6.5 Hz, 2H), 1.26 (t, J = 7.2 Hz, 3H). ”C NMR 5 171.6, 72.0, 70.5 (ZC), 70.4, 66.7, 60.4, 60.0, 35.1, 14.2. ESI — MS calc. for C10H2005Na [M+Na]" 243.1208, found 243.1208. 3-(2-(2-methoxyethoxy)ethoxy)propionohydrazide 5 Hydrazine hydrate (51%, 0.35 mL, 3 eq) is added to a on of ester 4 (0.42 g, 1.9 mmol) in ethanol (0.35 mL). After 16 h the solution is concentrated under reduced pressure to give the title hydrazide 5 (0.42 g, 107%). 1H NMR 5 7.80 (bs, 1H), 3.72 (t, J = 5.7 Hz, 2H), 3.64 (m, 6H), 3.59 (m, 2H), 3.39 (m, 3H), 2.48 (t, J = 5.7 Hz, 2H), 2.24 (bs, 2H). 13C NMR 6 172.1, 71.9, 70.5, 70.3, 70.2, 66.8, 59.0, 35.3. ESI — MS calc. for C8H19N204 [M+H]+ 201.1345, found 201.1341.

Example 10: Preparation of Oxime and Acyl Hydrazide derivatives of LAC-1 LAC-1 (0.29) is dissolved in CH3CI or EtOAc (2 mL). Aikoxyamine or acyl hydrazide 3a-d, 3f, 5 (0.43 or 0.23 mmol, 2.2 or 1.2 mmol/g LAC-1) and acetic acid (0.002 mL) are added and the solution stirred at room temperature until all the alkoxyamine or acyl hydrazide has d (2- h, TLC ce). The solvents are evaporated to give the oximes or acyl hydrazide. The 1H NMR spectra show conclusive evidence for formation of the oximes. The resonance for the H-1 protons of the alkoxyamine (3.47 — 3.84 ppm) disappears and is ed by a resonance at for the oxime (3.79 — 4.15 ppm). Levulinate methyl and methine resonance are shifted to lower field. A typical set of spectra is shown in Figure 1 and further spectra are shown in Figures 2-5.

Glass tion temperatures are listed in Table 4.

Table 4. Glass Transition ature (T9) of Cellulose Mixed Esters1 ,1 0* o o’lK .....as .- .....as as o v o ﬁg O o 0 W o 0 a O Y o o O O —N’O‘R N R —N’ \n/ (DLev 03) LAC-3 series LAC-5 series Derivatizing Tg (°C) R degree of Compound incorporation (mmol/g LAC-1) 97 None LAC-3a-2 3a 2.2 CH3(OCHZCH2)2 LAC-3a-1 3a m1.2 CH3(OCHZCH2)2 -2 3b 2.2 CH3(OCH2CH2)3 LAC-3c-2 3c -20 2.2 CH3(OCHzCH2)6_11 LAC-3c-1 lift:— 25 1.2 CH3(OCH2CH2)5.11 LAC-3d-1 _+_d 70 1.2 ‘l CH2(CH2)eCH3 LAC-3r-1_l’:ff 65 1.2 W LAC1 CH3(OCH20H2)2 1 Number and positions of substituents on the cellulose backbone of the three structures shown above are representative only. The ester substituents are randomly substituted on the ose backbone.

Example 11: Solubility of Cellulose Mixed Esters LAC-1 is soluble to at least 10% w/v in ethyl cellosolve, cyclohexanone, chloroform, dibasic ester, N—methylpyrrolidone, pyridine, e and acetone.

Table 5. Solubility of LAC-3b-2 Soluble Semisoluble Insoluble Dimethylformamide Butyl Acetate Amyl Alcohol ene Chloride Water Methanol Propylene n-butyl glycol ether Dioxane ylene n—butyl glycol ether Methyl Ethyl Ketone lsopropanol Acetone Toluene Ethyl Cellosolve l Chloroform Texanol Dimethylsulfoxide Dimethylacetamide N-methyl 2-pyrrolidone Acetic Acid Acetic Anhydride 2012/000228 Diacetone Alcohol exanone Di-Basic ester Pyridine Butyl Lactate Example 12: Solventborne Paint ations Gloss White Soya Lecithin 0.1 LAC—3b-2 43.0 Methyl dibasic ester* and cyclohexanone (50:50) 34.5 Titanium Dioxide 22.0 ite Clay 0.4 TOTAL 100.0 Pigment Volume Concentration (PVC) = 17%; Volume Solids (VS) = 47% * Mixture of dimethyl adipate, dimethyl glutarate and dimethyl succinate (approximately 17:66:17 °/o by mass).

Satin White Soya Lecithin 0.5 LAC-3b-2 28.0 Methyl dibasic ester* and cyclohexanone (50:50) 33.0 Titanium Dioxide 21.0 Nepheline Syenite 17.0 ite Clay 0.5 TOTAL 100.0 Pigment Volume Concentration (PVC) = 39%; Volume Solids (VS) = 46% * Mixture of dimethyl adipate, dimethyl glutarate and dimethyl succinate (approximately 17:66:17 % by mass).

Example 13: Waterborne Paint Formulations Example 13.1: A ~20% w/v binder emulsion of a pegylated oxime derivative of LAC-1.

LAC-3a-2 (1.84 g) is dissolved in ethyl acetate (2 mL) and triethylamine (20 pL) at ~60 °C. The surfactants l 7107 (183 mg) and Maxemul 7203 (200 pL) are added and the solution vigorously agitated with an UltraTurrex blender for 2-3 minutes at ~60 °C. To this solution is added water (4 mL) with continued agitation and heating at 80 °C. The emulsion is d to a m Film Forming Temperature (MFFT) bar and the minimum temperature range that a film is observed to form is recorded at 15-19 °C.

Example 13.2: A ~20% w/v binder emulsion of the octyl oxime derivative ofLA C-1.

Octyl—3d-1 (1.15 g) is dissolved in ethyl acetate (2 mL) and triethylamine (20 pL) at ~60 °C. The surfactants Maxemul 7107 (183 mg) and Maxemul 7203 (200 pL) are added and the solution vigorously agitated with an UltraTurrex blender for 2-3 s at ~60 °C. To this solution is added water (3 mL) with continued agitation and heating at 80 °C. The emulsion is applied to a Minimum Film Forming Temperature (MFFT) bar and the minimum temperature range that a film is ed to form is recorded at 33-37 °C.

Example 13.3: A zero VOC r dispersion.Butyl-levulinyl-acetyl cellulose (BLAC; DSW 2.89, DSLeV 0.35, DSBU 2.20, DSAc 0.34) was modified by the inclusion of xymethyl)hydroxylamine to from a DSCOOH 0.19 carboxylic acid-imine linked BLAC of acid number 31.6. Dissolution in acetone neutralized with triethylamine and rapid precipitation into water using a T-mixer or equivalent high-shear rapid mixing method generated a stable polymer dispersion of particle size <500nm. Evaporative distillation of the acetone to negligible levels (as determined by gas chromatography) generated a stable (>60 days without ying settling or gelling) dispersion of up to 30% w/w polymer in water. The dispersion readily forms a film at room temperature (18—25°C).

Example 13.4: Paint formulation from a zero VOC polymer dispersion.

The material generated in example 13.3 was mixed with a generic gloss mill—base [“Architectural coatings" Chapter 38 in “Surface Coatings" Volume 2, (2002) Southwood Press, Australia] containing the usual ingredients; e.g. titanium dioxide, water, anionic dispersants and crobial agents. Production of a film on an opacity card using a standard draw—down bar generated a flexible. continuous, , uniform film. The film characteristics could readily be r cation of the formulation, for example by the inclusion of plasticizer, for example, sucrose acetate isobutyrate (SAIB) or equivalent and by the inclusion of cross linking agents, for example adipic acid azide Although the invention has been bed by way of example, it should be appreciated the variations or modifications may be made without departing from the scope of the invention.

Furthermore, when known equivalents exist to specific features, such equivalents are incorporated as if specifically referred to in the specification.

INDUSTRIAL APPLICABILITY The present ion relates to cellulose-levulinyl mixed esters which are useful as starting materials for producing a variety of cellulose mixed ester derivatives. The ion further relates to cellulose mixed esters which are useful, for example, in coating compositions.

Claims

1. A cellulose mixed ester wherein, the total degree of substitution per anhydroglucose unit is about 2.5 to about 3.5; the residual hydroxyl functionality per anhydroglucose unit is about 0 to about 0.5; the degree of substitution per anhydroglucose unit by C2-C6 ester groups is about 0.5 to about 2.8; and the degree of substitution per anhydroglucose unit by levulinyl ester groups of about 0.2 to about 2.6.

2. The cellulose mixed ester according to claim 1, wherein the total degree of substitution per anhydroglucose unit is about 2.5 to about 3.3

3. The cellulose mixed ester according to claim 1 or claim 2, wherein the average molecular weight ns) of about 800 to about 105,000, alternatively the cellulose mixed ester has a weight average molecular weight of about 5000 to about 50000, or alternatively from about 5000 to about 40000, or alternatively from about 5000 to about 30000, or alternatively from about 5000 to about 20000.

4. The cellulose mixed ester according to any one of claims 1 to 3, wherein the degree of polymerisation is from about 2 to about 250, alternatively from about 5 to about 200, or alternatively from about 5 to about 100, or alternatively from about 5 to about 30.

5. The cellulose mixed ester according to any one of claims 1 to 3, wherein the defree of risation is from about 15 to about 50, more preferably about 20 to about 40, even more preferably about 30.

6. The cellulose mixed ester according to any one of claims 1 to 5, wherein the total degree of substitution per anhydroglucose unit of about 2.9 to about 3.2.

7. The cellulose mixed ester according to any one of claims 1 to 6, wherein the degree of substitution per oglucose unit by C2-C6 ester groups of about 0.5 to about 2.5, alternatively about 1.1 to about 2.25.

8. The cellulose mixed ester according to any one of claims 1 to 7, wherein a degree of substitution per anhydroglucose unit by levulinyl ester groups of about 0.75 to about 1.9 and a degree of tution per anhydroglucose unit by C2-C6 ester groups of about 1.1 to about 2.25.

9. The ose mixed ester having: a total degree of substitution per anhydroglucose unit of about 2.9 to about 3.3; residual hydroxyl onality per anhydroglucose unit of 0 to about 0.5; a degree of tution per anhydroglucose unit by C2-C6 alkyl ester groups of about 0.5 to about 2.8; a degree of substitution per oglucose unit by R1 ester groups of about 0.2 to about 2.6; where R1 is a l of formula (i): X where each X in the cellulose mixed ester is independently selected from the group consisting of: O, N-O-R2 and N-NH-C(=O)-R3, where R2 is CH3(OCH2CH2)2, CH3(OCH2CH2)3, CH3(OCH2CH2)6-11 or benzyl, alkyl or alkylcarboxy; R3 is CH3(OCH2CH2)2, CH3(OCH2CH2)3, CH3(OCH2CH2)6-11; provided that not all X groups in the cellulose mixed ester are O.

10. A cellulose mixed ester of formula (I): RO O where: n is an integer from 2 to 250; and each R in the cellulose mixed ester is independently selected from the group consisting of H, C2-C6 acyl and levulinyl; provided that not all R groups are H, and provided that not all R groups are C2-C6 acyl, and provided that not all R groups are selected from H and C2-C6 acyl.

11. A cellulose mixed ester of formula (II): R'O O (II) wherein: n is an integer from 2 to 250; and each R’ in the cellulose mixed ester is independently selected from the group consisting of H, C2-C6 acyl and R1; wherein: R1 is a radical of formula (i) (i) ; where each X in the cellulose mixed ester is independently selected from the group consisting of: O, N-O-R2 and N-NH-C(=O)-R3; each R 2 in the cellulose mixed ester is independently selected from the group consisting of CH3(OCH2CH2)2, CH3(OCH2CH2)3, CH3(OCH2CH2)6-11, alkyl, alkylcarboxy and benzyl; and each R3 in the cellulose mixed ester is independently selected from the group ting of CH3(OCH2CH2)2, CH3(OCH2CH2)3 and CH3(OCH2CH2)6- provided that not all R’ groups are H, and provided that not all R’ groups are C2-C6 acyl, and provided that not all R’ groups are selected from H and C2-C6 acyl.

12. The cellulose mixed ester ing to claim 1, wherein the cellulose mixed ester is Levulinyl-acetyl Ester of Cellulose (LAC-1) * O O * LAC-1 (DLev 0.8)

13. The cellulose mixed ester according to any one of claims 1 to 12, wherein the ose mixed ester is Levulinyl-butyryl Ester of Cellulose

14. The cellulose mixed ester according to claim 1, wherein Ds 3.15 esters per oglucose unit (AGU), Dlev 1.22. Tg 103.4 °C. Mw 9970, DP 27.

15. The ose mixed ester according to claim 1, wherein DTot is 3.05, DLev is 1.20, DAc is 1.85 and Tg 108 °C.

16. The cellulose mixed ester according to claim 1, wherein DTot 3.5, DLev 0.7, DAc 2.8, Tg 103°C, Mw 7600.

17. The cellulose mixed ester according to claim 1, wherein the cellulose mixed ester is Levulinyl-propionyl Ester of Cellulose.

18. A process for preparing a cellulose mixed ester, comprising the steps of: (a) combining an alkyl carboxylic ide, levulinic acid and one or more acids independently selected from the group consisting of Brønsted acids, Lewis acids, or mixtures of Lewis acids with Brønsted acids, with the o that when the Brønsted acid is phosphoric acid, a Lewis acid must be present; and (b) contacting the reaction mixture from step (a) with cellulose to produce a solution containing a cellulose mixed ester.

19. The process according to claim 18 wherein the reaction mixture is heated at about 120 ºC in step (b), more ably the cellulose and the on mixture are heated at about 120 ºC, for about 2 to about 6 hours in step (b), with the proviso that if a chlorinated solvent is used, it is heated at , or alternatively, the cellulose and the reaction mixture are heated using microwave energy in step (b).

20. The process according to claim 18 or 19, further comprising the step of: (c) diluting the solution obtained in step (b) with an aqueous solution containing ium acetate, sodium acetate, acetic acid or sodium bicarbonate to produce a diluted solution containing the cellulose mixed ester.

21. The process according to claim 18 to 20, further comprising the steps of: (d) mixing the diluted solution obtained in step (c) with water; and (e) recovering the ose mixed ester.

22. The ose mixed ester when produced by the process of any one of claims 18 to 21.

23. A method for preparing a cellulose mixed ester of formula (II) according to claim 11, r comprising the steps of: (a) reacting a cellulose mixed ester of formula (I) as defined above with an amine or an aryloxyamine or an acyl hydrazide to produce a cellulose mixed ester of formula (II).

24. A composition comprising one or more cellulose mixed esters ing to any one of claims 1 to 17.

25. A coating composition comprising one or more cellulose mixed esters according to any one of claims 1 to 17, wherein the coating composition may further comprise one or more solvents, optionally one or more additives.

26. A cellulose mixed ester according to any one of claims 1 or 9 to 11, substantially as herein described with reference to any one of the accompanying examples and/or figures thereof.

27. A s according to claim 18, substantially as herein described with reference to any one of the accompanying examples and/or figures thereof. WO 85397