Patent GB-392206-A (GB)
Title: Improvements in or relating to the manufacture of ether derivatives of cellulose
IPC: C08B11/04
Filed: 1931-08-14
Abstract: Hydroxy-alkyl ethers of cellulose are produced from cellulose which has not been greatly depolymerized by first converting to wet alkali cellulose, and without ageing for more than 24 hours, bringing into contact with up to about 20 per cent of ethylene oxide (or its equivalent of a higher non-substituted olefine oxide) based on the weight of the cellulose, or with a solution of such an oxide in an excess of organic solvent, so as to form a hydroxy-alkyl ether of cellulose containing less than one hydroxy-alkyl group to each unit of cellulose.  Wet alkali cellulose is defined as alkali cellulose which contains from 75 per cent to 350 per cent water based on the weight of the cellulose; preferably the alkali cellulose has a cellulose content of 25-35 per cent.  As initial material there is used cotton linters or a high grade chemical wood pulp, and mercerisation is carried out by means of caustic soda solution preferably of 30 per cent strength.  After ageing, ethylene oxide is introduced in restricted quantities, preferably in gaseous form, under normal or reduced pressures, and at temperatures below 45 DEG C.  In place of ethylene oxide, there may be used propylene oxide, butylene oxide, or amylene oxide.  The products are soluble or only partially soluble in dilute (5-15 per cent) caustic soda solutions, insoluble or only slightly soluble in caustic potash solutions, and insoluble in water and organic solvents.  Where the products are not completely soluble in dilute caustic soda solutions, which is particularly the case with the lower etherified products, the solubility may be increased by refrigerating the ether with dilute caustic soda solutions until a mass of crystals appears, according to the process described in Specification 389,534.  In the drawing (not shown) curves are shown indicating the effect of refrigeration on the solubility of various hydroxy-alkyl ethers in caustic alkali solutions.  In an example, (1) cotton linters are mercerized in 30 per cent caustic soda and squeezed to increase the cellulose content of the mass to about 30 per cent.  After not more than 24 hours, gaseous ethylene oxide is introduced in amount equal to 20 per cent of the weight of the cellulose, and the product worked up in one of two ways.  (a) Excess caustic soda is neutralized and the fibrous product washed and dried, or (b) the reaction product is stirred into water so that the cellulose concentration is about 5.5 to 8 per cent, the amount of caustic soda present being adjusted to form 2-2.5 per cent, and the solution formed into filaments, films, or the like, which are coagulated in an acid bath.  In another example, (2) wood pulp is mercerized in the manner given in the first example, and treated with about 7 per cent of gaseous ethylene oxide.  (a) Water is added to bring the caustic soda strength down to 4,75 per cent, and the mass is refrigerated at -20 DEG  C.  Caustic soda is added to bring the caustic soda concentration up to 6 per cent.  (b) Alternatively, one-third of the reaction mass is neutralized, washed and returned to the two-thirds portion, and the entire mass then treated as under (a).  In a further example (3) the procedure is similar to that of example (2b), but 12 per cent of ethylene oxide is employed, and the product is dissolved in 4-5 per cent caustic soda solution for the production of films.  (4) Alkali cellulose obtained as in examples (1) or (2) is reacted with a 20 per eent. solution of ethylene oxide in benzol so that not more than 20 per cent ethylene oxide combines with the cellulose.  (5) The procedure is as in (1), but there is used 12.4 per cent of propylene oxide instead of 20 per cent of ethylene oxide.  (6) Wet alkali celulose made as in (1) is introduced into a vessel having a perforated bottom, and below this there is placed enough of a mixture of caustic soda and ethylene chlorhydrin to generate 20 per cent of ethylene oxide based on the weight of cellulose.  (7) Wood pulp is mercerized and treated first with 12 per cent of its weight of ethylene oxide and then with 15 per cent of benzoyl chloride in excess of benzol.  The hydroxy-ethyl cellulose benzoate is dissolved in 4.75 per cent caustic soda solution, refrigerated as in examples (2) or (3), and dissolved in 7.5 per cent caustic soda solution for use in making filaments or films. The alkali cellulose may be first benzoylated and then etherified. The products may be used in the production of filaments, films, tubes, plastic mixtures, insulating goods, finishing materials, bottle caps and the like.  The Specification as open to inspection under Sect. 91 refers to the hydroxy-alkylation of carbohydrates in general, including cane sugar, starch, glucose, cellulose and materials containing cellulose, hydrated or hydrolised cellulose, raw or purified viscose, recovered celluloses and partially esterified or etherified celluloses.  The hydroxy-alkylating agents include ethylene oxide and its homologues, and the chlorhydrins corresponding to these oxides, for example, ethylene chlorhydrin, propylene chlorhydrin, and glycerol monochlorhydrin, and are not restricted regarding the proportions used, which may be as high as 200 per cent in the case of ethylene oxide.  The etherifying agent may also be used in the liquid phase. Water soluble products are stated to be useful as sizes for textiles, adhesives (with or without sodium silicate), fillers for adhesives, bases for explosives, fillers for inks, or the like.  The following additional examples are given : (1) Alkali cellulose is allowed to age for 24 hours or more and caused to react with 75-95 per cent or more of ethylene oxide based on the weight of the cellulose. (2) Wet alkali cellulose is submerged in or wetted with liquid ethylene oxide for 20 hours at 4 DEG  C.  (3) Corn starch is mercerized with 20 per cent caustic soda solution and treated with 15-17 per cent of ethylene oxide.  (4) Wood pulp is mercerized in 20 per cent caustic soda and drained to 7-9 times its weight, after which the mass is cooled to 0 DEG  C. and 6 per cent of ethylene chlorhydrin added. (5) Cellulose is converted to alkali cellulose using 40 per cent caustic soda solution, and reacted with 18 per cent of its weight of ethylene chlorhydrin.  The product is then refrigerated in 4.75 per cent caustic soda solution.  (6) Alkali cellulose made as in the previous example is treated with 22.5 per cent of glycerol monochlorhydrin.  This subject-matter does not appear in the Specification as accepted.ALSO:Hydroxy-alkyl ethers of cellulose are produced from cellulose which has not been greatly depolymerized, by first converting to wet alkali cellulose, and without ageing for more than 24 hours, bringing into contact with up to about 20 per cent of ethylene oxide (or its equivalent of a higher non-substituted olefine oxide) based on the weight of the cellulose, or with a solution of such an oxide in an excess of organic solvent, so as to form a hydroxy-alkyl ether of cellulose containing less than one hydroxy-alkyl group to each unit of cellulose.  Wet alkali cellulose is defined as alkali cellulose which contains from 75 per cent to 350 per cent water based on the weight of the cellulose; preferably the alkali cellulose has a cellulose content of 25 to 35 per cent.  The Specification as open to inspection under Sect. 91 refers to the hydroxy-alkylation of carbohydrates in general, including cane sugar, starch, glucose, cellulose and materials containing cellulose, raw or purified viscose, recovered celluloses, hydrated or hydrolized celluloses, and partially esterified or etherified celluloses.  The hydroxy - alkylating agents include ethylene oxide and its homologues, and the chlorhydrins corresponding to these oxides, e.g., ethylene chlorhydrin, propylene chlorhydrin, and glycerol monochlorhydrin, and are not restricted regarding the proportions used, which may be as high as 200 per cent in the case of ethylene oxide.  The etherifying agent may also be used in the liquid phase. Water soluble products are stated to be useful as sizes for textiles, as adhesives (with or without sodium silicate), and as fillers for adhesives.  This subject-matter does not appear in the Specification as accepted.