Mixtures for improving the stability of additive packages

A process for improving the stability of an additive with detergent action in a gasoline additive package, the process comprising:

• applying
• at least one olefin-carboxylic acid copolymer (A) with a number-average molecular weight Mn of from 0.5 to 10 kDa (determined by gel permeation chromatography with tetrahydrofuran and polystyrene as standard), obtainable by
• in a first reaction (I), copolymerizing
• (Aa) at least one ethylenically unsaturated mono- or dicarboxylic acid or derivative thereof,
• (Ab) at least one α-olefin having from at least 12 up to and including 30 carbon atoms,
• (Ac) optionally, at least one further aliphatic or cycloaliphatic olefin which has at least 4 carbon atoms and is different than (Ab), and
• (Ad) optionally, one or more further copolymerizable monomers other than monomers (Aa), (Ab), and (Ac), selected from the group consisting of
• (Ada) vinyl esters,
• (Adb) vinyl ethers,
• (Adc) (meth)acrylic esters of alcohols having at least 5 carbon atoms,
• (Add) allyl alcohols or ethers thereof,
• (Ade)N-vinyl compounds selected from the group consisting of vinyl compounds of heterocycles containing at least one nitrogen atom, N-vinylamides, and N-vinyllactams,
• (Adf) ethylenically unsaturated aromatics,
• (Adg) α,β-ethylenically unsaturated nitriles,
• (Adh) (meth) acrylamides, and
• (Adi) allylamines,
• followed by
• in a second optional reaction (II) partly or fully hydrolyzing and/or saponifying anhydride or carboxylic ester functionalities present in a copolymer obtained from (I), the second reaction being run at least when the copolymer obtained from reaction (I) does not comprise any free carboxylic functionalities;
• to
• a gasoline additive package comprising at least one quaternary nitrogen compound (B) as an additive with detergent action and at least one fatty acid, fatty acid ester, or oligomerized fatty acid,
• wherein the gasoline additive package has a content of 0.01 to 40 wt. % of said at least one olefin-carboxylic acid copolymer (A) and a content of 5 to 40% by weight of the at least one quaternary nitrogen compound (B),
• wherein the gasoline additive package with the at least one olefin-carboxylic acid copolymer (A) exhibits less demixing after storage at −20° C. for 3 days, compared to the gasoline additive package without the at least one olefin-carboxylic acid copolymer (A), and
• wherein the nitrogen compound (B) is of formula
• wherein in this formula
• PIB is a polyisobutenyl residue having a number average molecular weight Mn of from 750 to
• 1300 g/mol,
• R is methyl, and
• A− is salicylate or methyloxalate,
• wherein the gasoline additive package further comprises as additive component (F) at least one carrier oil which is substantially free of nitrogen, selected from polyesters, polyalkoxylates, polyethers, and alkylphenol-initiated polyethers,
• wherein the gasoline additive package does not comprise an organic nitrate, and
• wherein the process further comprises adding the gasoline additive package to gasoline which is not diesel fuel.