GB421115A - Improvements in or relating to the production of cellulose ester or ether moulding powders - Google Patents

Abstract

Moulding powders are made by agitating a cellulose ester or ether and a plasticizer in suspension in an aqueous medium without grinding and in the presence of a wetting or a dispersing agent, for example, turkey red oil, the substance having the Registered Trade Mark "Monopol" oil, sulphonated pine oil, or soap. Water-insoluble swelling agents for the cellulose derivative, such as aliphatic, cyclic, or aromatic hydrocarbons, e.g. benzene, toluene, xylene, pine oil, or the substance having the Registered Trade Mark "Tetralin," or watersoluble swelling agents, such as alcohols and ketones, e.g. acetone, cyclohexanol, or cyclohexanone, may also be present. The cellulose derivative is preferably treated in the form of a fine uniform powder. Suitable combinations of dispersing agents and swelling agents are turkey red oil with "Tetralin" and sodium silicate, or with xylene, or "Tetralin," cyclohexanol, and soap. The amount of dispersing or wetting agent, or mixture thereof with swelling agent should be small, e.g. 0,5-5 per cent of the weight of cellulose derivative, and the amount of swelling agent should not be so great as to give a mixture with any substantial solvent action of the cellulose derivative and plasticizer. The amount of aqueous medium is preferably large, e.g. 4-25 times the weight of the cellulose derivative. The latter may be agitated for some time with the other components before adding the plasticizer. Thus, powdered cellulose acetate is stirred with 20 times its weight of water containing a mixture of turkey red oil and xylene equal to 1 per cent of the cellulose acetate for 1 hour, and xylene monomethyl sulphonamide added with vigorous stirring which is continued for some time. Absorption of the plasticizer may take place at raised temperatures, e.g. 35-100 DEG C. After absorption and removal of the liquid, the powder may be washed and any residual volatile matter removed. The cellulose derivative may be added to an aqueous dispersion or colloidal solution of the plasticizer and dispersing or other agents. The plasticizers may be aromatic sulphonamides, sulphonanilides or other sulphonarylides, phthalate plasticizers, tartrate esters, aromatic phosphates, triacetin, diphenylol propane or other phenol-ketone condensation products, tertiary butyl phenols, or camphor. They may be present from less than 10 per cent up to say 100 per cent by weight of the cellulose derivative. Resins, stabilizers such as urea or its derivatives, dyes, lakes, pigments and effect materials, and fillers such as silica gel or wood flour may be incorporated at any stage. Non-inflammators such as mineral phosphates, halogenated phenols and aromatic amines and their acidyl derivatives, especially the brominated acidylated amines of Specification 319,073, [Class 2 (ii)], may be added. Such halogenated compounds may themselves be the sole plasticizers. Substances combining with halogen such as dicyandiamide may be incorporated. Cellulose esters and ethers referred to include esters such as cellulose laurate and naphthenate, cellulose acetonitrate, or mixed ethers or ether-esters. According to an example, 100 parts of powdered acetone-soluble cellulose acetate are stirred with 1800 parts of water, and 0,5 parts each of turkey red oil and xylene added. The mixture is stirred for 1 hour, 50 parts dimethyl phthalate and 10 parts triphenyl phosphate added, the batch heated to 60 DEG C., stirred for 20-60 minutes, allowed to settle, and the powder separated and dried. The Specification as open to inspection under Sect. 91 comprises also the use of swelling agents alone for facilitating incorporation of the plasticizer in the cellulose derivative, and is not restricted to the use of an aqueous medium but to any medium having little or no solvent action on the cellulose derivative and plasticizer. Other plasticizable substances such as synthetic resins, polymerized vinyl esters or other vinyl compounds may be used in place of cellulose derivatives, and the invention is not restricted to the production of moulding powders. This subject-matter does not appear in the Specification as accepted.