Patent GB-913939-A (GB)
Title: Improvements in and relating to corrosion inhibition
IPC: C23F11/167
Filed: 1960-10-10
Abstract: A corrosion inhibitor for metal, especially aluminium, surfaces in contact with aqueous media such as in I.C. engine cooling systems evaporators, refrigeration equipment or heat exchangers comprises the addition reaction product of at least one organic amine with a mixture of a monobasic and a dibasic acid having the formula:- <FORM:0913939/III/1> wherein R is an alkyl radical having 1 to 6 carbon atoms, an alkoxy-substituted alkyl radical having from 1 to 6 carbon atoms in the alkyl grouping and from 1 to 6 carbon atoms in the alkoxy grouping, a phenyl or a benzyl radical, x is 2 or 3, y and z are each 1 or 2 and the sum of y and z is 3.  From 0,04 to 1,0% by weight of the inhibitor is added to the aqueous media.  Included in the acid mixtures are 2-butoxyethyl acid phosphates, 2-ethoxyethyl acid phosphates, 2-methoxyethyl acid phosphates, 2-methoxyisopropyl acid phosphates, 2-(2-ethoxyethoxy) ethyl acid phosphates, 3-(3-methoxypropoxy) propyl acid phosphates, 3-[3-(3-methoxypropoxy) propoxy] propyl acid phosphates, 2-(2-methoxy ethoxy) ethyl acid phosphates and 2-benzyloxyethyl acid phosphates.  The organic amines used may include alkyl amines having from 2 to 14.  C atoms and alkanol amines such as diethylamine, dipropylamine di-isopropyl amine butylamine, dibutylamine, isobutylamine and diethanolamine, high molecular weight primary amines including abietyl amine and dehydroabietyl amine and mixtures of these amines.  In an example 0,12 parts by weight of an inhibitor prepared by reacting P2O5 with butyl "Cellosolve" (Registered Trade Mark) to produce mixed butyl "Cellosolve" acid phosphates and then reacting these mixed acids with diethylamine was mixed with 98,88 parts of an aqueous medium consisting of a mixture of 1 part of ethylene-glycol with 2,5 parts of water and aluminium test pieces were placed in the solution.  No pitting of or deposition on the metal surface occurred after seven days at 60 DEG C. and the solution remained clear.ALSO:An addition reaction product of at least one organic amine with a mixture of a monobasic and a dibasic acid having the formula:-  <FORM:0913939/IV (b)/1> wherein R is an alkyl radical having 1 to 6 carbon atoms, an alkoxy-substituted alkyl radical having from 1 to 6 carbon atoms in the alkyl grouping and from 1 t 6 carbon atoms in the alkoxy grouping, a phenyl or benzyl radical, x is 2 or 3 y and z are each 1 or 2 and the sum of y and z is 3 may be obtained by first reacting an equivalent of P2O5 with three equivalents of an alkoxyalkanol such as butyl "Cellosolve" (Registered - Trade Mark) as shown by the following equation:-  <FORM:0913939/IV (b)/2> and then reacting the mixed acids with the amine, for example diethylamine.  Specified acid mixtures are 2-butoxyethyl acid phosphates, 2-ethoxyethyl acid phosphates, 2-methoxyethyl acid phosphates, 2-methoxyisopropyl acid phosphates, 2-(2-ethoxyethoxy) ethyl acid phosphates, 3-(3-methoxypropoxy) propyl acid phosphates, 3-[3-(3-methoxypropoxy)propoxy]propyl acid phosphates, 2-(2-methoxyethoxy)ethyl acid phosphates and 2-benzyloxyethyl acid phosphates.  The amines used include alkyl amines having from 2 to 14 C atoms and alkanol amines, such as diethylamine, dipropylamine, diisopropylamine, butylamine, isobutylamine, t - C12H25NH2, t-C14H20NH2 and diethanolamine.  The products are used as corrosion inhibitors more particularly for aluminium surfaces (see Group XVIII).