A paper substrate comprising modified low molecular weight pva with functional vinyl groups

A method for manufacturing a paper substrate which is suitable for binding silicone in a catalytic hydrosilation reaction, the method comprising steps of

• dissolving polyvinyl alcohol which has a weight average molecular weight of less than 50000 g/mol and degree of hydrolysis in the range of 70% to 99% into water, thereby obtaining a water-based solution containing dissolved polyvinyl alcohol,
• adding reactant which is an organic molecule that contains a catenated carbon structure having at least 4 carbon atoms, an aldehyde group and a functional vinyl group into the water-based solution containing the dissolved polyvinyl alcohol, thereby obtaining a reaction mixture
• reacting the reactant with the dissolved polyvinyl alcohol in a water-based acetalization reaction, thereby forming acetalized polyvinyl alcohol which contains functional vinyl groups, wherein the functional vinyl groups are part of catenated carbon structures which contain at least 4 carbon atoms, and which have an acetal connectivity with the backbone chain of the acetalized polyvinyl alcohol, and
• coating a cellulose fiber-based support layer with the acetalized polyvinyl alcohol, thereby forming a hydrophobic primer layer and the paper substrate, wherein the vinyl group molality of the acetalized polyvinyl alcohol is equal to or higher than 0.2 millimoles per gram of the acetalized polyvinyl alcohol.