GB776487A - Food containers - Google Patents

Abstract

A can release agent for food containers, which comprises a nitrogen-containing solid synthetic material of m.pt. above 155 DEG F., is incorporated in a lacquer composition comprising a synthetic resin can coating lacquer containing a conjugated drying oil for application to the interior surface of the container. 4-12 per cent by weight of the agent may be suspended in a solvent dispersion of the lacquer or added at the end of the cooking and bodying operation. In an example, 7 1/2 per cent by weight of a condensation product of stearamide and formaldehyde powdered to particle size 3 microns was suspended in a composition containing 100 lb. phenolic resin, 10 U.S. gals. chinawood oil, 10 U.S. gals. dehydrated castor oil, 40 U.S. gals. mineral spirits and 1.6 lb. 6 per cent manganese naphthenate drier. The suspended material was applied and then baked at 300 DEG F. for 10 minutes. In further examples, distearoyl tetraethylene pentamine and its mono- and penta-methylene derivatives were powdered to particle size 3 microns and 7 1/2 per cent to 12 per cent of the powdered products were suspended in compositions of (1) rosin modified phenolic resin, dehydrated castor oil, mineral spirits and cobalt naphthenate, (2) maleic resin (obtained from maleic anhydride and 1-pimaric acid) dehydrated castor oil, soyabean oil, mineral spirits and cobalt naphthenate, (3) rosin modified phenolic resin, rosin, ester gum, tung oil, linseed oil, mineral spirits and a manganese drier. The containers may be of metal, plastic, glass or paper.ALSO:Nitrogen-containing solid synthetic materials of m.p. above 155 DEG F. (68 DEG C.) are described, such as amides or cycloimidines, or their derivatives melting above 212 DEG F. in which an acyl group from a C10 to C29 fatty acid, or a mixture of such fatty acids, is attached to a nitrogen atom derived from an amine. The following groups of compounds are specified: N-acyl chain compounds, bridged N-acyl chain compounds, alkyl cycloimidine compounds, bridged alkyl cycloimidine compounds, bis cyclo compounds and their reaction products. Thus the synthetic material may be a diamide obtained by condensing with one mol. of polyamine a mixture in excess of one mol. of a C10-C29 fatty acid and a molecular proportion of a C1-C9 fatty acid to make two mols. of fatty acid, a compound such as N,N1-distearoyl ethylene diamine being the reaction product of 2 mols. of stearic acid with 1 mol. of ethylene diamine, an alkylene-bridged amine obtained by condensing a carboxylic acid with an amine and then reacting 2 mols. of the condensation product with one mol. of a lower aliphatic aldehyde such as gaseous or polymerized formaldehyde, e.g. by reacting 2 mols. of diacid tetra-ethylene pentamine with 5 mols. of aldehyde at 150-250 DEG C., by condensing a polycarboxylic acid, e.g. an aromatic dicarboxylic acid with a long chain normal saturated amine having at least 10 carbon atoms in its molecule or by condensing a carboxylic acid with an aromatic amine or polyamine, an alkyl cycloimidine prepared by reacting one mol. of a fatty acid having at least 10 carbon atoms in the acyl group with one mol. of a polyamine to liberate 1.5-2.0 mols. of water (see Fig. 23) wherein R is from a saturated or unsaturated C10-C29 series fatty acid, an alkylene bridged alkyl cycloimidine prepared by reacting 2 mols. of the alkyl cycloimidine with one mol. of a lower aliphatic aldehyde, e.g. reacting in the above proportions, stearic acid with ethylene diamine at 120-300 DEG C., cooling the product to just above the freezing point and adding paraformaldehyde giving the product, m.p. 288 DEG F., shown in Fig. 25, the product obtained by heating at 120-300 DEG C, 1 mol. of a C10-C29 fatty acid such as stearic acid with 1 mol. of a polyalkylene polyamine such as diethylene triamine; the two cycloimidine ring formations for the 1,2 and 1,3 closures, m.p. 212 DEG F. and 194 DEG F. respectively, are shown in Figs. 26 and 27, the reaction products of the above two alkyl cycloimidine compounds with an aldehyde giving four structures, Figs. 30, 31, wherein 2 <FORM:0776487/IV(b)/1> <FORM:0776487/IV(b)/2> <FORM:0776487/IV(b)/3> <FORM:0776487/IV(b)/4> <FORM:0776487/IV(b)/5> <FORM:0776487/IV(b)/6> <FORM:0776487/IV(b)/7> <FORM:0776487/IV(b)/8> <FORM:0776487/IV(b)/9> mols. of the 1,2 compound are reacted with 1 and 2 mols. of formaldehyde respectively and Figs. 32, 33 correspondingly for the 1,3 ring compound, bis cycloimidine compounds prepared by reacting at 150-300 DEG C. 2 mols. of a fatty acid containing at least 10 carbon atoms in the acyl group with a polyalkylene polyamine having at least 4 nitrogen atoms in the molecule to evolve three-four mols. of water of condensation; these compounds have the general formula shown in Fig. 35, wherein R is a normal alkyl group of at least 9 carbon atoms, R1 is a hydrogen atom or a lower alkyl group, n is a whole number greater than one and X is zero or a whole number, and aldehyde-reacted bis cycloimidines by reacting the bis cycloimidines with an aldehyde at 150-300 DEG C. In specific examples the condensation product, of m.p. 266 DEG F., obtained by heating at 248 DEG F. 100 parts of stearamide and 28 parts of 36 per cent formaldehyde for an hour and then at 329 DEG F. for 5 hours was powdered to a particle size of 3 microns. In a further example 113 parts of red oil and 21.5 parts of formamide were heated together at 446 DEG F. for 30 minutes, 30 parts of the resultant "oleyl" amide, crystallized from acetone, and 9 parts of 38 per cent formaldehyde solution were heated at 248 DEG F. for 1 hour with constant stirring and then at 329 DEG F. for an additional hour; the resultant condensation product had a m.p. of 219.2-224.6 DEG F. In a further example 100 parts of coconut oil acid amides, 28 parts of 40 per cent formaldehyde solution and 2 parts of concentrated sulphuric acid were heated to 248 DEG F. for 1 hour with constant stirring and then at 329 DEG F. for 3 hours giving a condensation product of m.p. 257-268 DEG F. Many additional examples are given.ALSO:Food containers e.g. cans for luncheon meat, corned beef hash, spiced ham, potted meat and salmon, are coated on the interior surfaces with a can release agent comprising a nitrogen-containing solid synthetic material of melting point above 155 DEG F. (68 DEG C.) which is of wax-like character and preferentially is adherent to the container surfaces. Containers so treated may be sterilized prior to filling them with the food and food may be cooked in contact with the coating. The can release agent may be dissolved or suspended in a lacquer containing a conjugated drying oil for application to the interior surfaces of the containers. The preferred agents are amides or cycloimidines or their derivatives of m. pt. above 212 DEG F., in which an acyl group from a C10 to C29 fatty acid, or a mixture of such fatty acids, is attached to a nitrogen atom derived from an amine. The following groups of compounds are specified: N - acyl chain compounds, a bridged N - acyl chain compounds, alkyl cycloimidine compounds, bridged alkyl cycloimidine compounds, bis cyclo compounds and their aldehyde reaction products; examples include N, N1 distearyl ethylene diamine, and the condensation proucts of stearamide with formaldehyde, red oil with formamide and formaldehyde, coconut oil acid amides with formaldehyde. The containers may be of metal, plastic, glass or paper.