Method for cold rolling metals using an aqueous lubricant comprising at least a carboxylic acid, a phosphate ester and a wax

Abstract

The invention concerns a method for cold rolling metals using an aqueous lubricant comprising: (1) at least a mixture based on at least an acid selected among saturated or unsaturated mono- or poly-carboxylic acids, comprising 5 to 40 carbon atoms; at least an acid phosphate ester of formula (RO)x—P(═O)(OH)x′, wherein: R is a hydrocarbon radical, optionally polyalkoxylated; x and x′ being equal to 3; the carboxylic acid and/or the acid phosphate ester being optionally neutralised by an organic or mineral base; and (2) at least a natural or synthetic wax exhibiting a melting point not less than 50° C. and having an average particle size ranging between 0.5 and 10 μm. The use of said lubricant enables to increase the productivity of the method by at least 15% relative to a method using a conventional lubricant.

1 . A cold rolling process for metals using an aqueous lubricant comprising (1) at least one mixture based on at least one acid chosen from saturated or unsaturated, monocarboxylic or polycarboxylic acids containing 5 to 40 carbon atoms; on at least one acid phosphate ester of formula (RO) x —P(═O) (OH) x′ , in which formula R is an optionally polyalkoxylated hydrocarbon radical, x and x′ being equal to 1 or 2, provided that the sum of x and x′ is equal to 3; the carboxylic acid and/or the acid phosphate ester being optionally neutralized by an organic or mineral base; and (2) at least one natural or synthetic wax having a melting point not less than 50° C. and having a mean particle size ranging between 0.5-10 μm.  
     
     
         2 . The process as claimed in one of the preceding claims, characterized in that the carboxylic acid of the mixture (1) comprises one or more carboxylic functional groups and at least one linear or branched, alkyl radical or alkenyl radical having one or more ethylenically unsaturated groups, said radicals optionally being substituted with one or more hydroxyl radicals.  
     
     
         3 . The process as claimed in one of the preceding claims, characterized in that the acid phosphate ester of the mixture (1) corresponds to the following formula: [R(OA) y ] x —P(═O) (OH) x′ , in which formula the radicals R, which may or may not be identical, represent a hydrocarbon radical containing 1 to 30 carbon atoms, the radicals A, which may or may not be identical, represent a linear or branched alkylene radical containing 2 to 4 carbon atoms, y, which is an average value, is between 0 and 100 and x and x′ are equal to 1 or 2, provided that x+x′=3.  
     
     
         4 . The process as claimed in one of the preceding claims, characterized in that the mineral base among the basic compounds creating monovalent species, chosen among alkali-metal and ammonium hydroxides, hydroxycarbonates, carbonates and bicarbonates.  
     
     
         5 . The process as claimed in one of the preceding claims, characterized in that the organic base is chosen from primary, secondary or tertiary amines or polyamines, comprising at least one linear, branched or cyclic hydrocarbon radical having 1 to 40 carbon atoms, optionally substituted with one or more hydroxyl radicals and/or one or more oxyalkylene groups.  
     
     
         6 . The process as claimed in one of the preceding claims, characterized in that the waxes are natural waxes chosen from paraffin waxes, synthetic waxes comprising ester and/or amide functional groups.  
     
     
         7 . The process as claimed in the preceding claim, characterized in that the synthetic waxes correspond to the following formula: R′—CO-A-(CR″ 2 ) n -A-CO—R′, in which formula the radicals R′, which may or may not be identical, represent an aliphatic radical containing 5 to 22 carbon atoms, said radical being saturated or having one or more conjugated or nonconjugated carbon-carbon double bonds; the radicals R″, which may or may not be identical, represent a hydrogen atom or an alkyl radical containing 1 to 4 carbon atoms; n represents an integer between 2 and 12; and the radicals A, which may or may not be identical, represent —O— or —NH—.  
     
     
         8 . The process as claimed in either of claims  6  and  7 , characterized in that the waxes have a melting point not less than 80° C.  
     
     
         9 . The process as claimed in one of the preceding claims, characterized in that the mixture (1) comprises at least one metal in the form of a multivalent ion; the assembly being in the form of lamellar crystallites of length ranging between 0.1 and 100 μm, of width ranging between 0.5 and 30 μm and of thickness ranging between 5 and 200 nm, comprising a stack of organic phases (O) and of aqueous solutions (A) in the sequence O/[A/O]n, n being an integer different from 0 and such that the stack has a thickness of 5 to 200 nm, the organic phases comprising the mixture (1) and said metal.  
     
     
         10 . The process as claimed in the preceding claim, characterized in that the length of the lamellar crystallites is between 0.5 and 20 μm, the width of the lamellar crystallites is between 0.5 and 10 μm and the thickness of the lamellar crystallites is between 10 and 100 nm.  
     
     
         11 . The process as claimed in the preceding claim, characterized in that the metal is in the form of a multivalent cation chosen from columns IIA, VIII, IB, IIB and VIB, with the exception of cobalt and nickel, by themselves or as mixtures.  
     
     
         12 . The process as claimed in one of the preceding claims, characterized in that the total content of compounds (1) and (2) in the aqueous lubricant during its use is between 0.05 and 10% by weight of the lubricant, preferably between 0.05 and 5% by weight of the lubricant.  
     
     
         13 . The process as claimed in one of the preceding claims, characterized in that it is applicable to the cold rolling of metals such as steels, stainless steels, copper, zinc, tin and copper-based alloys (bronze, brass).  
     
     
         14 . The process as claimed in the preceding claim, characterized in that it is applicable to the cold rolling of stainless steel.