IL35214A - Rust inhibitor - Google Patents

Description

inhibitor la This invention is concerned with a fo iron against This product relies upon the chelating property iron with natural organic compounds known as tannic acids more natural It is well known that phenolic substances having at least two vicinal phenolic hydroxy groups or a group in position relative to a phenolic group are likely to with the ferric a complex molecule whic the iron atom is entrapped by three organic The formation of such a ferric chelate causes the appearance of a blue colour shade of which varies according to the nature the phenolic For it is possible to produce a ferric chelate by reaction with salicylic thereby synthesizing a complex molecule which the iron atom is linked to three organic molecules through linkages The chemical chelation reaction starts at anodic sites or the metal where iron is ioniaed with liberation of It is according to that mechanism that natural polyphenols inhibit rust this use of aqueous solutions of polyphenols from various plant sources well The molecula weight has a substantial influence on of the Thus quebracho which has only two phenolic functions likely to forms with iron a slightly crosslinked which gives only The conversion of iron oxides with inorganic particularly phosphoric is well The inorganic acid 2 reacts with rust to ferric and ferroue such as ferrous and ferric which cover the metallic but the iron atoms are not linked to each so that there is lack of resistance to In an attempt to find compromise with the view of improving the protection of iron against it has also been suggested to a mixture of polyphenols and phosphoric the ferrous and ferric salts are not linked to each since the polyphenol reacts more slowly than the inorganic it cannot give rise to the stabilizing reaction with the converted In accordance with the present there provided a rust that comprises at least a tannic a catalyst of initiating the chelation of iron atoms and a agent capable of linking two or more molecules of the resulting the tannic acid is of a purity from to and completely soluble in and has a viscosity of 150 to 200 centipoises at by weight in ethanol at a temperature of It preferably has a weight higher than 2000 and a hydroxy phenolic function number of at least the tannic acid is a pyrogallic tannic a metapolygallie or gallic acid an ellagic acid or a quinic ester of gallic or metapolygallie The catalyst may be an organic polycarboxylic which may be saturated or hydroxylated or alicyclic or The catalyst may be also an organic polysulfonic acid or an amino When an inorganic the catalyst may he an electron or a Lewie The thus defined catalysts promote the penetration Inhibitor solution through the laminated layers of they initiate and catalyse the chelation reaction of iron with tannic acid and they contribute to substantial improvement the adhesion of the ferric chelate to the metallic The chelation reaction of iron requires an absorption of the electrons liberated at the metal anodic In this since the inorganic compounds function as Lewis acids or electron they catalyse the chelation Aluminium salts such as aluminium iron salts such as ferric chloride and tin salts such as stannic chloride accelerate chelation reaction and make it more The agents are introduced in order to increase the molecular weight of the ferric thereby making it still more resistant to corrosive Examples such agents are saturated unsaturated aliphatic dialdehydes such as aromatic aliphatic diamines such as hexamethylene diamines and aromatic diamines such as paraphenylene Use of an at least difunctional organic compound having functions capable of reacting with tannic acid and binding together two or more ferrotannic chelate molecules will be As proved by several the quantitative limits of the components of the rust inhibitor may be but preferred quantitative limits are given in the table Maximum percentage by weight in the by weight in the Components mixture mixture Tannic acid 15 20 Solvent boiling at 12 20 Catalyst 15 agent 15 Volatile solvent 15 35 Water 15 40 It will be noted that the composition the rust Inhibitor as defined is able to inhibit adhering rust of thicknesses up to 500 The reaction speed of iron and iron oxides Chelation is a function the humidity the ambient The reaction is faster and more complete when the relative humidity of the atmosphere is store than 50 On the basis of can declare that the study of the potentiometric curves of the rust treated by the herein defined inhibitor shows that the current corresponding to an posed potential above millivolts to the dissolution potential does not go above milliamperes per square centimeter when measured i distilled Under the same conditions and at an Identical untreated rust presents a current Cf milliamperes per square 5 rust inhibitor according to the invention may be used under varying more particularly in accordance with the intended effects and the requirements in produced Varying compositions may be provided in accordance with the invention by the addition of components having a secondary it being understood such components do not interfere with function of the rust inhibitor according to the The invention is illustrated i the following in which all parts and percentages are by EXAMPLE 1 15 parts of previously purified tannic acid and parts of ethylene glycol monoethyl ether are mixed in a planetary The mixture is heated to with tumbling until a homogeneous syrupy paste is there are added 6 parts of oxalic acid and 10 parts of aqueous formaldehyde solution which are admixed the The resulting paste is then diluted with 25 parts of isopropanol and parts of EXAMPLE 2 15 parts of previously purified tannic of acid and parts of glycol are mixed in a planetary It is then heated to with tumbling until a geneous paste is whereupo 10 parts of hexamethylene diamine is incorporated into the The paste then diluted with 40 parts of water and 15 parts of EXAMPLE 3 In a planetary kneader 14 parta ethylene glycol monoethyl ether is to with good parts of previously purified tannic acid then completely dissolved in 3 parts of malonic parts of paraphenylene amine and 10 parts of a ferric chloride solution are then When a homogeneous mixture is the paste is diluted 25 parts of water and 30 parts of EXAMPLE 4 15 parts of previously purified tannic acid and 14 parts of ethylene glycol monoethyl ether are mixed in a planetary The mixture then heated to until a homogeneous syrupy paste is of glyoxal and 6 parts of phthalic acid are The resulting mixture is diluted with parts of isopropanol and 18 parts of EXAMPLE 5 14 parts of ethylene glycol monoethyl 15 parts of previously tannic acid and of oxalic acid are introduced into a planetary mixture is heated to for 15 thereby obtaining a perfectly homogeneous whereupon 10 parts of a aluminium sulphate solution and 4 parts of hexamethylene diamine are 7 The resulting paste is diluted with 30 parts of isopropanol and 25 parts of The solution obtained in these various examples may be applied to a rusty surface previously cleared of non adhering After several a uniform layer of bluish black ferric chelate is typical examples on one the fundamental principle on the other the large possible variations within the specific These examples have not any limitative insufficientOCRQuality

Claims (1)

1. 8 A rust inhibitor that comprises at least a tannic a catalyst capable of initiating the chelation of iron atoms and a agent capable of linking two or more molecules of the resulting A rust inhibitor according to Claim in which the tannic acid has a molecular higher than 2000 a hydroxy phenolic function number of at least A rust inhibitor according to Claim 1 in which the tannic acid is a purity to and completely soluble in and has a viscosity of 150 200 centipoises at by in ethanol at a temperature of rust according to any one of Claims 1 in which the tannic acid is a pyrogalllc tannic A rust inhibitor accordin to any one of Claims 1 to in which the tannic acid is a gallic or metapolygallic acid A rust inhibitor according to any one of Claims 1 to in which the tannic acid is a ellaglc acid A rust inhibitor according any one of Claims 1 to in which the tannic is a quinic ester of gallic or metapolygallic A rust inhibitor according to any one of Claims in which the catalyst an organic saturated or unsaturated polysulfonic or amino 9 A rust accordin to Claim in which the catalyst is a hydroxylated polycarboxylic A rust accordin to Claims 8 or in which the catalyst is a saturated or unsaturated polycarboxylic alicyclic A rust inhibitor according to Claims 8 or in which the catalyst is a polycarboxylic aromatic A rust inhibitor accordin to any one of Claims in which the catalyst is an inorganic electron A rust according to Claim 12 in which the catalyst is a Lewis A rust inhibitor according any one of Claims in which the is an at least organic compound presenting functions capable of jsacting with tannic acid and of bindin together two or more molecules of rust Inhibitor accordin to any one of i which the agent is A rust inhibitor according t one Claims in which agent is a saturated or unsaturated aliphatic A according to Claim in which the dialdehyde is A rust according to any one Claims in the agent is aromatic A rust inhibitor accordin to any one of 10 A rust inhibitor according to in which the diamine is hexamethylene A rust inhibitor according to any one of Claims in which the agent an aromatic A Inhibitor according to Claim in which the diamine paraphenylene inhibitor according to any one of Claims in whic the components are admixed in percentage by weight in the following tannic acid from solvent boiling at above from catalyst from to agent from volatile solvent from to water from to rust inhibitor substantially as hereinbefore described reference to the foregoing For the Applicants insufficientOCRQuality