GB663621A - Method of preparing a hydrophilic cellulose gel - Google Patents

Abstract

A hydrophilic cellulose gel is obtained by treating cellulosic material first with a solution of caustic soda or caustic potash of 18-40 per cent concentration by weight in a proportion of 1 kilogram of dry cellulose to at least 5 litres of alkali solution at a temperature not exceeding 20 DEG C., e.g. at 5 DEG C., then removing water in excess of 35-45 per cent of the mass, heating the mass to a temperature of 40-70 DEG C. under elevated pressure, preferably 5-10 atmospheres, and maintaining the mass at such a temperature and pressure until there is formed a depolymerized cellulose gel from which the fibrous structure of the original cellulose cannot be regenerated. The time for the first step may be 2-12 hours and the time for the heating step may be 2-24 hours. Heating may be carried out in the presence of air or oxygen. Iron oxide, alumina, or a mixture thereof, may be employed as a catalyst. The gel obtained is miscible with water and may be converted into a soft or more or less fluid paste or homogeneous sol. It may be neutralized by addition of acid. It may be used in the production of soaps, toothpastes, creams, ointments, and floor waxes. When dehydrated, a translucent, horny, product is obtained. In an example, purified straw pulp is immersed in a 40 per cent solution of caustic potash and left for 2 hours at 5 DEG C. The mass is drained and pressed till it retains 40 per cent of moisture. The mass is then broken up and left in an autoclave at 50 DEG C. and 5 atmospheres pressure, in presence of iron or aluminium oxide, for 6 hours to obtain the cellulosic gel product. An example of the production of a soap substitute is given. The hydrophilic cellulose gel containing 18-20 per cent of caustic soda is mixed with a foaming agent such as a di-isopropyl-naphthalene-b -sulphonic acid; a water-soluble resin, such as a naphthalene sulphonic acid-formaldehyde condensation product, is added, and, if desired, also zinc or titanium oxide, trisodium phosphate, colouring material, and perfume. The mix is worked into a paste of the desired consistency, preferably at 50-70 DEG C. The alkaline cellulosic gel may be used as a neutralizing agent in the preparation of the foaming agent. In an example, naphthalene is mixed with sulphuric acid and the temperature brought to 50 DEG C. Alkaline cellulosic gel is added in small portions. Isopropyl alcohol is then added and the temperature is raised to 70 DEG C. and maintained for 2 hours. Separation of the foaming agent from unreacted components is effected by decantation. A further proportion of the cellulosic gel may then be added. Examples are given of the production of condensation products of naphthalene sulphonic acids with formaldehyde. Naphthalene is sulphonated with sulphuric acid at 165-170 DEG C. and then condensed with formaldehyde at 110 DEG C. The resin obtained, which is fluid at the elevated temperature, is poured into a high-speed mixer containing milk of lime sufficient to neutralize the acid resin. Specification 507,138 is referred to.ALSO:A hydrophilic cellulose gel obtained by reacting cellulose material with caustic alkali under heat and pressure (see Group IVa) is incorporated in detergent compositions. In an example, the hydrophilic cellulose gel containing caustic soda is mixed with a di-isopropyl-naphthalene-b -sulphonic acid which acts as a foaming agent, and with a water-soluble resin such as a naphthalene sulphonic acid and formaldehyde condensation product. If desired, there may also be added zinc oxide, titanium oxide, trisodium phosphate, colouring matter, and perfume. The mix is worked into a paste, preferably at 50-70 DEG C.