Filler paste for use in basecoats for coating polyolfin substrates, basecoats, and process for the direct coating or polyolefin substrates

Filler paste A) comprising

• a1) from 5 to 50% by weight of a polyurethane resin or a plurality of polyurethane resins,
• a2) from 0.5 to 13% by weight of one or more chlorinated polyolefins having a chlorine content of from 10 to 40% by weight, based on the solids content of the chlorinated polyolefins, and having a number-average molecular weight of from 5000 to 150,000,
• a3) from 0 to 50% by weight of one or more physically drying binders which are different from a1),
• a4) from 5 to 35% by weight of compounds selected from the group consisting of fillers extenders, and mixture thereof
• a5) from 0 to 15% by weight of pigments selected from the group consisting of color pigments, special-effect pigments, and mixtures thereof
• a6) from 0 to 5% by weight of one or more rheological additives, and
• a7) from 20 to 60% by weight of organic solvents,
• the sum of components a1) to a7) being in each case 100% by weight.