Thickeners and binders forming gels in gasoline

A powder of particles of an emulsion polymer capable of swelling and forming a gel in gasoline, said polymer comprising:

• (A) at least 80 percent by weight of solid polymer of at least one alkyl ester of methacrylic acid having at least 4 carbon atoms in the alkyl or of a mixture of at least one alkyl ester of acrylic acid and at least one ester of methacrylic acid each having at least 4 carbon atoms in the alkyl,
• (B) at least one crosslinking molecule,
• (C) 0 to 20 percent by weight of said polymer of at least one monoolefinically unsaturated aromatic comonomer, and
• (D) 0 to 10 percent of at least one monoolefinically unsaturated comonomer not soluble in gasoline at room temperature, said particles consisting of
• (1) a core polymer which is from 40 to 80 percent by weight of the particle and in which crosslinking molecule (B) is from 0.1 to 2 percent, by weight of the core, of at least one monomer having at least two polymerizable olefinic carbon-carbon double bonds whose reactivity in polymerization is comparable with that of monomer (A), and of
• (2) a shell polymer covering said core polymer, which is from 60 to 20 percent by weight of the particle wherein said monomer (A) is isobutyl methacrylate or cyclohexyl methacrylate and in which crosslinking molecule (B) is from 0.05 to 4 percent, by weight of the shell, of at least one graftlinking monomer having an olefinic carbon-carbon bond whose reactivity in polymerization is comparable with that of comonomers (A) and having at least one further olefinic carbon-carbon bond of lower reactivity.