GB284846A - A process for the production of cellulose by decomposition of vegetable fibres - Google Patents

Abstract

284,846. Strecker, O. C. Jan. 13, 1927. Pulp, preparation of.-A high yield of practically pure cellulose is obtained from the most varied kinds of vegetable fibres such for example as red pine wood, beech wood, bamboo, straw and resinous woods such as Scotch fir, by the use of boiling lyes containing one or more soluble oxy compounds of the iso-cyclic series in which at least one hydrogen atom of the oxy group has been replaced by a metal, the metals preferred being those of the alkali group, alkaline earth metals, and metals of the magnesium group. As example of oxy compounds are mentioned Phenols, such as phenol and cresol, alcohol phenols such as phenol alcohol, Cyclohexenol, Hydrogenated phenols such as cyclohexanol, naphthols such as alpha-naphthol, Hydrogenated naphthols such as oxy-naphthalene tetrahydride or decahydride, methylcyclo-hexanol, Polyphenols such as resorcin, Oxysulphones such as sulphonoxybenzene, Sulpho and carbo acids of the above substances and their salts including metal salts which decompose on heating to form oxy-compounds and either sulphites or carbonates such as oxybenzene sulphonic acid or oxybenzene carboxylic acid and their sodium salts, Functional derivatives of phenol and its homologues especially those containing alkyl or aryl groups which split off on fusing with alkali. Homologues of the substances mentioned and their derivatives mav be used and also such substances containing chlorine, bromine, iodine or nitro groups substituted for hydrogen in either the ring or in the side chain. The substances are used preferably as solutions or as permanent emulsion, and substances such as soaps of castor oil, cyclohexanol and salts of humic acid may be added to render the emulsions permanent. Penetration of the vegetable fibres may be assisted by the addition of alkaline, neutral, or slightly acid salts such as tri sodium phosphate Na3 PO 4' weak acids with basic, slightly alkaline, neutral, or acid reaction, metallic bases, aliphatic or aromatic alcohols, phenol alcohol, as well as their homologues and functional derivatives. Catalytically acting substances such as barium peroxide may also be used. The reaction mav be expedited by boiling under pressure, and under such conditions the attack of the lyes on the cellulose fibres themselves may be checked by adding substances of neutral or alkaline reaction and reducing effect to the boiling lye, either before commencing the process or during boiling. As examples of these substances are mentioned neutral sulphites such as sodium sulphite, sodium formate, sodium malate, sodium prenyl sulphonate, their homologues and substitution products, stannous oxide, and the like. The metal cation in the lye combines with the acids formed from the vegetable fibres and thus disappears thereform. A metal compound is added to the lye during the boiling operation to make good the loss in this respect. It is preferred to use the same metal for this purpose and. alkaline bases or alkaline salts capable of hydrolytically splitting off alkali, oxyhydrates of alkaline earth metals such as barium hydrate, or of metals of the magnesium group may be used. The combination of the metals with the acidic substances (anions) obtained from the vegetable fibres may produce a boiling lye from the vegetable fibres themselves, so that the lye can be used repeatedly. It is only necessary to remove a small portion of the lye and make it up to the required strength after each boiling operation. In doing so, care must be taken that the sodium hydroxide or the like added is completely combined. A boiler capable of being continuously charged and unloaded should be used or a series of boilers should be connected to form a battery. The lye can thus be transferred to a new charge without cooling,. and loss of heat prevented.