Patent GB-976335-A (GB)
Title: Derivatives of cellulose crystallite aggregates
IPC: C08B1/02
Filed: 1960-12-22
Abstract: Reaction products are made by treating cellulose crystallite aggregates with oxidising, etherifying or esterifying agents, the crystallite aggregates comprising the crystalline residue of the acid hydrolysis of cellulose and being characterized by the uniformity of the lengths of the constituent chains thereof, the chain length uniformity being defined by the fact that the crystallite aggregates have a level-off average degree of polymerization of 15-375 anhydroglucose units, the constituent chains of each aggregate being separate from and free of the chains in neighbouring aggregates, the crystallite aggregates having a sharp X-ray diffraction pattern indicative of a substantially crystalline structure, a chemical purity of at least 95% and a particle size of less than 300 microns, usually less than 250 microns.  The constituent chains of the crystallite aggregates may have a potential aldehyde group or a hydroxyl group or a carboxyl group in the 1-carbon position of the end anhydroglucose units.  Reaction products obtained by the use of oxidisine agents may have a plurality of carbonyl linkages incorporated in aldehyde, carboxyl or mixed aldehyde-carboxyl radicals, the degree of substitution of carbonyl-containing radicals in the chains of the crystallite aggregates being preferably at least 0.01 carbonyl-containing radical per anhydroglucose unit.  Preferred aldehyde derivatives have the aldehyde radicals in the 2 and 3-carbon positions of at least a portion of the anhydroglucose units, and preferred carboxyl derivatives have the carboxyl radicals in the 2 and 3 or 6 carbon positions of at least a portion of the anhydroglucose units.  Aldehyde derivatives, especially dialdehydes, may be prepared by the oxidation of the cellulose crystallite aggregates with periodic acid, which opens the anhydroglucose ring at the 2, 3 position and converts the hydroxyl groups at these positions to aldehyde groups (Example 1); or by the use of lead tetra acetate, which opens the ring at the same position, or by electrolysis of a sodium iodate solution in the presence of the aggregates (Example 6). Carboxyl derivatives may be made by oxidising the aggregates with nitrogen dioxide, which oxidises the hydroxyl groups attached to the 6 carbon of the anhydroglucose ring (Example 4), or by oxidation of the 2,3 dialdehyde derivative with hydrogen peroxide to yield a 2,3 dicarboxylate (Example 5).  Mixed derivatives, containing both aldehyde and carboxyl groups, may be made by treating an aqueous dispersion of the aggregates with sodium hypochlorite (Example 2), with calcium hypochlorite, with hydrogen peroxide (Example 3), or with chromic acid or potassium dichromate.  The dialdehydes are hydroplastic, i.e. may be moulded by mixing with water and subjecting the mass to heat and pressure, when cross-linking takes place to produce a material having a high resistance to moisture (Example 7) which can be used as a dielectric (Example 8) or as a thermosetting plastic material. Mixtures of the dialdehyde derivatives (as binders) with wood flour, carboxyl derivatives or unreacted aggregates (Example 9) (as fillers) may be similarly used.  The carboxyl derivatives may be used as fillers in urea-formaldehyde melamine-formaldehyde, polyamide, polyester and polyolefin compositions; and in the form of their sodium salts, as cloud-forming agents in aqueous liquids, e.g. soft drinks.  The mixed aldehyde-carboxyl derivatives are hydroplastic, and may be used as paste thickeners in printing inks and foods.  The ether derivatives of the invention are characterised by having a plurality of -OR groups where O is oxygen and R is a radical selected from the class consisting of aliphatic radicals, substituted aliphatic radicals, and mixtures thereof, the O being connected to an aliphatic carbon atom in the R radical. Etherification is effected in conventional manner. Examples illustrate the preparation and purification of sodium carboxy methyl cellulose, (Example 10), benzyl cellulose (Example 11), ethyl cellulose (Example 12), methyl cellulose (Example 13), cyanoethyl cellulose (Example 14) and hydroxyethyl cellulose (Examples 15 and 16). Methods of preparing other cellulose ethers are briefly discussed, particularly the carboxyalkyl and hydroxyalkyl ethers in general, ethoxyethyl propyloxyethyl and benzyloxyethyl ethers, dialkylaminoalkyl ethers, and cyanoalkyl ethers. The ethers and the esters are chiefly useful in making films and fibres, (see Division B5) when of high level-off D.P. and as coatings and sizes e.g. for films and paper when of lower level-off D.P. (see Division B2).  The preparation and purification of ester derivatives is described, in the following examples: Nitrocellulose (Example 17), cellulose sulphate (Example 18), cellulose acetate (Examples 19 and 20). Phosphate esters may be made by reacting the aggregates with a mixture of phosphoric acid and phosphorus pentoxide at 1-10 DEG C. The preparation of numerous other esters is briefly discussed. Specifications 874,945 and 970,111 are referred to.ALSO:Carboxyl derivatives of cellulose crystallite aggregates, the crystallite aggregates comprising the crystalline residue of the acid hydrolysis of cellulose and being characterized by the uniformity of the lengths of the constituent chains thereof, the chain length uniformity being defined by the fact that the crystallite aggregates have a level-off average degree of polymerization of 15-375 anhydroglucose units, the constituent chains of each aggregate being separate from and free of the chains in neighbouring aggregates, the crystallite aggregates having a sharp X-ray diffraction pattern indicative of a substantially crystalline structure, a chemical purity of at least 95% and a particle size of less than 300 microns are used, in the form of their sodium salts, as cloud-forming agents in soft drinks. The carboxyl derivatives may be made by oxidizing the aggregates with nitrogen dioxide, which oxidizes the hydroxyl groups attached to the 6 carbon of the anhydroglucose ring (Example 4), or by oxidation of the 2,3 dialdehyde derivative with hydrogen peroxide to yield a 2,3 dicarboxylate (Example 5). Specifications 874,945 and 970,111 are referred to.ALSO:"Cellophane" (Registered Trade Mark) is coated with the reaction products obtained by treating cellulose crystallite aggregates with etherifying or esterifying agents, the crystallite aggregates comprising the crystalline residue of the acid hydrolysis of cellulose and being characterized by the uniformity of the lengths of the constituent chains thereof, the chain length uniformity being defined by the fact that the crystallite aggregates have a level-off average degree of polymerization of 15-375 anhydroglucose units, the constituents chains of each aggregate being separate from and free of the chains in neighbouring aggregates, the crystallite aggregates having a sharp X-ray diffraction pattern indicative of a substantially crystalline structure, a chemical purity of at least 95% and a particle size of less than 300 microns, usually less than 250 microns.  The ether derivatives are characterized by having a plurality of -OR groups where O is oxygen and R is a radical selected from the class consisting of aliphatic radical, substituted aliphatic radicals, and mixtures thereof, the O being connected to an aliphatic carbon atom in the R radical. Specifications 874,945 and 970,111 are referred to.ALSO:Mixed aldehyde-carboxyl derivatives of cellulose crystallite aggregates, the crystallite aggregates comprising the crystalline residue of the acid hydrolysis of cellulose and being characterized by the uniformity of the lengths of the constituent chains thereof, the chain length uniformity being defined by the fact that the crystallite aggregates have a level-off average degree of polymerization of 15-375 anhydroglucose units, the constituent chains of each aggregate being separate from and free of the chains in neighbouring aggregates, the crystallite aggregates having a sharp X-ray diffraction pattern indicative of a substantially crystalline structure, a chemical purity of at least 95% and a particle size of less than 300 microns are used as paste thickness in foods.  The mixed derivatives, containing both aldehyde and carboxyl groups, may be made by treating an aqueous dispersion of the aggregates with sodium hypochlorite (Example 2), with calcium hypochlorite, with hydrogen peroxide (Example 3), or with chromic acid or potassium dichromate.  Specifications 874,945 and 970,111 are referred to.