Impregnation process for a fibrous substrate, a liquid monomer syrup for the impregnation process, its method of polymerization and structured article obtained thereof

An impregnation process for impregnating a fibrous substrate, wherein said fibrous substrate is made of long fibres having an aspect ratio of at least 1000, said fibers having a diameter between 0.005 micrometers and 100 micrometers, and said process comprises a step of impregnating said fibrous substrate with a liquid monomer syrup comprising:

• a) a (meth)acrylic polymer,
• b) at least one monomer (A) chosen from a (meth) acrylic monomer or a vinyl monomer or mixture thereof,
• c) at least one initiator or initiating system for starting the polymerization of the (meth) acrylic monomer,
• d) optionally another (meth) acrylic monomer (B)
• wherein the at least one monomer (A) chosen from (meth) acrylic monomer or vinylic monomers has a boiling point of at least 115° C. at 1013 mbar and/or a vapour pressure of less than 25 mbar at 20° C. and
• wherein the other (meth)acrylic monomer B has a boiling point less than 115° C. at 1013 mbar and/or a vapour pressure of more than 25 mbar at 20° C.,
• and wherein said liquid monomer syrup has a dynamic viscosity of a value in the range from 10 mPa*s to 10000 mPa*s,
• wherein monomer (A) is present at more than 50 wt % and (meth)acrylic monomer (B) presents less than 50 wt % of the total sum of monomers (A) and (B) present in the liquid monomer syrup, and wherein monomer (A) is selected from the group consisting of cyclohexyl methacrylate, isobornyl acrylate, isobornyl methacrylate, heptyl methacrylate, n-octyl acrylate, 2-octyl acrylate, iso-octyl acrylate, 2-ethylhexyl methacrylate, butyl diglycol methacrylate, dicyclopentenyloxyethyl methacrylate, ethoxy ethyl methacrylate, isobutyl methacrylate, n-butyl methacrylate, tert-butyl methacrylate, hydroxyl propyl methacrylate, styrene, alpha methyl styrene, ortho-, beta- or para-methyl styrene, tert-butyl styrene, nitro styrene, N-vinylpyrrolidone, and mixtures thereof.