Latex for bonding fiber structures

A polymer latex obtained from an emulsion polymerization in an aqueous medium of a mixture of ethylenically unsaturated monomers comprising:

• (a) 61 wt.-% to 75 wt.-% of at least one aliphatic conjugated diene, wherein the conjugated diene is selected from the group consisting of 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, isoprene and combinations thereof;
• (b) 10 wt.-% to 29 wt.-% of at least one vinyl aromatic compound, wherein the vinyl aromatic compound is selected from the group consisting of styrene, α-methyl styrene, p methylstyrene, t-butylstyrene, 2-vinyltoluene and combinations thereof;
• (c) 0.5 to 5 wt.-% of at least one ethylenically unsaturated silane bearing at least one silicon bonded hydrolysable group;
• (d) 0.1 to 8 wt.-% of at least one ethylenically unsaturated acid;
• and
• (e) up to 20 wt.-% of at least one further ethylenically unsaturated compound different from any of compounds (a) to (d),
• the weight percentages being based on the total amount of monomers and adding up to 100 wt.-%, and wherein the mixture of ethylenically unsaturated monomers comprises:
• (e1) 0.5 to 5 wt.-% of at least one amide of an ethylenically unsaturated acid,
• wherein the emulsion polymerization is carried out using a seed latex.