Antimisting additives for aviation fuels

A method for dissolving in a liquid, mainly aliphatic, hydrocarbon fuel having a flash point not less than 90.degree. F. an additive comprising:

• (a) from about 30% to about 40% by weight of a polymer in finely divided form which is a copolymer of (i) at least 75% by weight of tert-butylstyrene, (ii) from 1% to 24% by weight of a second monomer selected from the acrylic and methacrylic esters of aliphatic monohydric alcohols containing from 1 to 4 carbon atoms, 2-ethoxyethyl methacrylate, acrylonitrile, vinyl acetate, styrene and vinyltoluene, and (iii) from 1% to 10% by weight of methacrylic acid, the aggregate of monomers (i), (ii) and (iii) being 100%, the polymer having the following characteristics:
• (1) it is soluble in AVTUR 50 aviation kerosene;
• (2) a 0.3% by weight solution of the polymer in AVTUR 50 aviation kerosene has a relative viscosity in the range of 1.25 to 2.6 and a differential orifice flow rate in the range 2.5 to 7 ccs per 30 seconds;
• (b) from about 0.01 to about 0.2 mole per 100 grams of the polymer of an organic amine selected from the group consisting of alkyl monoamines having 1 to 12 carbon atoms, alkanolamines containing from 4 to 10 carbon atoms, and heterocyclic atoms;
• and
• (c) a hydroxylic carrier liquid making up the remainder of the additive which in the presence of the amine does not dissolve the polymer or is at most only a weak swellant for the polymer, the hydroxylic carrier liquid comprising 2-methylpentane-2,4-diol;
• the concentration of the polymer in the fuel being in the inclusive range from 0.055 to 1% by weight,
• wherein the improvement comprises additionally adding to the fuel, so that there is present in the fuel when the said additive has been added to it, an additional component comprising one or more compounds selected from the following:
• (I) water:
• to an extent of from 0.1% to 1.25% by weight of the additive plus the additional component;
• (II) glycerol:
• to an extent of from 0.1% to 1.25% by weight of the additive plus the additional component;
• (III) ethylene glycol:
• to an extent of from 0.1% to 2% by weight of the additive plus the additional component;
• and
• (IV) a straight chain aliphatic carboxylic acid having 1-4 carbon atoms present to an extent of from 10% to 200% molar equivalent of the amount of amine present.