Precursor composition for acrylic thermoplastic composites and its method of preparation and use

A liquid composition LC1 suitable for impregnation of a fibrous substrate comprising fibres, the preparation of a prepreg and a polymeric composite, said liquid composition comprising,

• a) a (meth)acrylic polymer (P1),
• b) a (meth)acrylic monomer (M1), wherein the monomer (M1) is a mixture of at least 60% by weight methyl methacrylate and at least one other monomer, and
• c) two initiators (Ini1) and (Ini2), wherein the quantity of the two initiators (Ini1) and (Ini2) together in the composition is between 0.75 phr and 15 phr relative to the sum of (meth)acrylic monomer (M1) and (meth)acrylic polymer (P1),
• said liquid composition having a dynamic viscosity of between 10 mPa*s and 10,000 mPa*s at 25° C., wherein the initiator (Ini1) is a photoinitiator configured to be activated by absorption of radiation and the initiator (Ini2) is a heat activated initiator configured to be activated by heat,
• wherein the (meth)acrylic polymer (P1) is present in a proportion of not more than 30% by weight relative to the sum of (meth)acrylic monomer (M1) and (meth)acrylic polymer (P1),
• wherein the quantity of initiator (Ini1) in the composition is between 0.5 phr and 2 phr relative to the sum of (meth)acrylic monomer (M1) and (meth)acrylic polymer (P1), and
• wherein the initiator (Ini1) is selected from the group consisting of acetophenones, alkoxyacetophenones, hydroxyacetophenones, alkylaminoacetophenones, benzoin ethers, phosphine oxides;
• benzophenones, thioxanthones, chinones, benzoyl formate esters, dibenzylidene ketones or coumarins;
• dyes, triazines and derivatives, fluorones and derivatives, cyanines and derivatives, saffranines and derivatives, 4,5,6,7-tetrachloro-3′, 6′-dihydroxy 2′, 4′ 5′, 7′-tetraiodo-3H-spiro [isobenzofuran-1,9′-xanthen]-3-one, pyrylium and thiopyrylium and derivatives, thiazines and derivatives, flavins and derivatives, pyronines and derivatives, oxazines and derivatives, and rhodamines and derivatives, and
• wherein initiator (Ini2) has a half-life time t1/2 of at least 1 hour at a temperature of at least 60° C.