Patent GB-442885-A (GB)
Title: Improvements in or relating to substances for use in the pickling and cleaning of metals
IPC: C23G1/06
Filed: 1934-08-17
Abstract: Corrosion inhibitors for use in metal pickling and cleaning baths are formed by the reaction between a carboxylic acid or its anhydride and sulphurized quinoidine.  A carboxylic acid which is soluble in dilute sulphuric acid is preferably employed.  When the acid is liquid at ordinary temperature, the reaction is effected by dissolving the sulphurized quinoidine in the concentrated acid. When a solid acid is used the acid and the sulphurized quinoidine may be mixed and heated to melting temperature, or the sulphurized quinoidine may be suspended in a concentrated solution of the acid and the suspension heated.  The products which can be obtained by precipitation or evaporation are stated to be soluble in water and dilute and concentrated acids.  The solution of the reaction product in the carboxylic acid may be added direct to the pickling bath, or the product obtained by precipitation or evaporation may if desired be redissolved in concentrated sulphuric or hydrochloric acid and the solution added to the bath.  Numerous examples of acids which may be reacted with sulphurized quinoidine are given.  Specification 411,907 is referred to.ALSO:Corrosion inhibitors for use in metal pickling and cleaning baths are formed by the reaction between a carboxylic acid or its anhydride and sulphurized quinoidine.  A carboxylic acid which is soluble in dilute sulphuric acid is preferably employed. When the acid is liquid at ordinary temperature, the reaction is effected by dissolving the sulphurized quinodine in the concentrated acid. When a solid acid is used the acid and the sulphurized quinoidine may be mixed and heated to melting temperature, or the sulphurized quinoidine may be suspended in a concentrated solution of the acid and the suspension heated.  The products which can be obtained by precipitation or evaporation are stated to be soluble in water and dilute and concentrated acids.  The solution of the reaction product in the carboxylic acid may be added direct to the pickling bath, or the product obtained by precipitation or evaporation may be dissolved in concentrated sulphuric or hydrochloric acid and the solution added to the bath.  Numerous examples of acids which may be reacted with sulphurized quinoidine are given. Specification 411,907, [Group IV], is referred to.ALSO:Corrosion inhibitors for use in metal pickling and cleaning baths are formed by the reaction between a carboxylic acid or its anhydride and sulphurized quinoidine.  A carboxylic acid which is soluble in dilute sulphuric acid is preferably employed.  When the acid is liquid at ordinary temperature, the reaction is effected by dissolving the sulphurized quinoidine in the concentrated acid. When a solid acid is used the acid and the sulphurized quinoidine may be mixed and heated to melting temperature, or the sulphurized quinoidine may be suspended in a concentrated solution of the acid and the suspension heated.  The products which can be obtained by precipitation or evaporation are stated to be soluble in water and dilute and concentrated acids.  The solution of the reaction product in the carboxylic acid may be added direct to the pickling bath, or the product obtained by precipitation or evaporation may be dissolved in concentrated sulphuric or hydrochloric acid and the solution added to the bath.  Numerous examples of acids which may be reacted with sulphurized quinoidine are given. Specification 411,907 is referred to.