Cellulose derivatives, e.g. esters and ethers and artificial and natural resins are plasticized by means of neutral esters of dicarboxylic acids or esters of aromatic monocarboxylic acids which contain a residue of an ester of a hydroxy fatty acid having not more than five carbon atoms. Besides aliphatic, aromatic-aliphatic and cyclic alcohols, phenols and ether-alcohols may be used in the formation of the esters. In examples, the plasticizing agents are prepared as follows: (1) monosodium ethyl phthalate, prepared by refluxing phthalic anhydride with alcohol and adding anhydrous sodium carbonate is condensed with ethyl-chloracetate and treated with decolourizing charcoal; methyl, propyl, butyl, benzyl and phenyl sodium phthalate may similarly be condensed with the chloracetic esters or the a or b chlorpropionic esters of methyl, propyl, butyl, amyl or benzyl alcohol or of phenol, cresol or mono alkyl ethers of glycol; (2) mono potassium methyl phthalate, prepared by treating phthalic anhydride with methanol and adding potassium carbonate is condensed with ethyl chloracetate. The following compositions are described in further examples: (3) cellulose nitrate is dissolved in a mixed solvent comprising ethyl or butyl acetate, denatured alcohol or butyl alcohol and a hydrocarbon such as benzene or toluene, and the ethyl glycollate ester of chlorbenzoic acid or of mono ethyl phthalic acid added as a plasticizing agent before using the mixture for making films: (4) a cellulose acetate film is prepared as in example 3 using acetone in place of the mixed solvent; (5) similar films are prepared containing the methylglycollate ester of monomethylphthalic acid or the ethyl glycollate ester of monoethyl ester of succinic or diglycollic acid as plasticizing agents; (6) methylglycollate ester of monoethylphthalic acid is incorporated with a phenol aldehyde polymerized product either in molten condition or in solution in alcohol; (7) an alkyl resin prepared from phthalic anhydride, glycerol and a small amount of glycol is used for the production of varnishes, lacquers or moulding compositions after the addition of a plasticizing agent; (8) a polymerized styrol resin dissolved for example in acetone is plasticized by means of the ethyl glycollate ester of monobutyl ester of phthalic acid; (9) a vinyl ester resin, e.g. polymerized vinylacetate in powdered form is sprayed with the ethylglycollate ester of monoethylester of phthalic acid and is then ready for moulding. Lactic, b -hydroxy propionic and a and b -hydroxy butyric acids may be used in the preparation of the plasticizing agents, and the following dibasic acids are specified: maleic, adipic, diglycollic and thiodiglycollic acids. The production of threads is mentioned. The Specification as open to inspection under Sect. 91 comprises also the manufacture and use as plasticizing agents of esters obtained by condensing a salt of a polycarboxylic acid or of an acid ester of a polycarboxylic acid with an ester of a lower halogen fatty acid. Oxalic acid is specified as a polycarboxylic acid which may be used. This subject-matter does not appear in the Specification as accepted.ALSO:Cellulose derivatives, e.g. esters and ethers, and artificial and natural resins are plasticized by means of neutral esters of dicarboxylic acids or esters of aromatic monocarboxylic acids which contain a residue of an ester of a hydroxy fatty acid having not more than five carbon atoms. Besides aliphatic, aromatic-aliphatic and cyclic alcohols, phenols and ether-alcohols may be used in the formation of the esters. In examples, the plasticizing agents are prepared as follows: (1) monosodium ethyl phthalate is condensed with ethyl-chloracetate and treated with decolorizing charcoal; methyl, propyl, butyl, benzyl and phenyl sodium phthalate may similarly be condensed with the chloracetic esters or the a or b chlorpropionic esters of methyl, propyl, butyl, amyl or benzyl alcohol or of phenol, cresol or monoalkyl ethers of glycol; (2) monopotassium methylphthalate is condensed with ethylchloracetate. In a further example, an alkyd resin prepared from phthalic anhydride, glycerol and a small amount of glycol is used for the production of varnishes or lacquers after the addition of a plasticizing agent. Lactic, b -hydroxypropionic and a - and b -hydroxy butyric acids may be used in the preparation of the plasticizing agents, and the following dibasic acids are specified: maleic, adipic, diglycollic and thiodiglycollic acids. The Specification as open to inspection under Sect. 91 comprises also the manufacture and use as plasticizing agents of esters obtained by condensing a salt of a polycarboxylic acid or of an acid ester of a polycarboxylic acid with an ester of a lower halogen fatty acid. Oxalic acid is specified as a polycarboxylic acid which may be used. This subject-matter does not appear in the Specification as accepted.ALSO:Cellulose derivatives, e.g. esters and ethers, and artificial and natural resins are plasticized by means of neutral esters of dicarboxylic acids or esters of aromatic monocarboxylic acids which contain a residue of an ester of a hydroxy fatty acid having not more than five carbon atoms. Besides aliphatic, aromatic-aliphatic and cyclic alcohols, phenols and ether-alcohols may be used in the formation of the esters. In examples: (1) methylglycollate ester of monoethylphthalic acid is incorporated with a phenolaldehyde polymerized product either in molten condition or in solution in alcohol; (2) an alkyd resin prepared from phthalic anhydride, glycerol and a small amount of glycol is used for the production of moulding compositions after the addition of a plasticizing agent; (3) a polymerized styrol resin dissolved for example in acetone is plasticized by means of the ethyl glycollate ester of monobutyl ester of phthalic acid; (4) a vinyl ester resin, e.g. polymerized vinylacetate in powdered form is sprayed with the ethylglycollate ester of monoethylester of phthalic acid and is then ready for moulding. Lactic, b -hydroxypropionic and a - and b -hydroxy butyric acids may be used in the preparation of the plasticizing agents, and the following dibasic acids are specified: maleic, adipic, diglycollic and thiodiglycollic acids. The production of threads is mentioned. The Specification as open to inspection under Sect. 91 comprises also the manufacture and use as plasticizing agents of esters obtained by condensing a salt of a polycarboxylic acid or of an acid ester of a polycarboxylic acid with an ester of a lower halogen fatty acid. Oxalic acid is specified as a polycarboxylic acid which may be used. This subject-matter does not appear in the Specification as accepted.