Composite polyester films suitable in particular as supports for magnetic recording materials, and magnetic recording materials thus produced
AssigneeRhone-Poulenc Films
InventorsJean-Francois Fiard, Etienne Fleury, Dominique Gerwig, Sylvianne Traversier, Louis Vovelle
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Abstract
The invention relates to composite films consisting of a semicrystalline polyester substrate film, free from filler and with a roughness Ra lower than or equal to 0.01 .mu.m, carrying on at least one of its faces a coating based on a modified polymer obtained by polymerization of one or more acrylic monomers in the presence of a water-dispersible sulphonated copolyester.
Claims32
An oriented polyester film comprising (1) a polyester substrate having first and second sides, (2) an outer abrasion resistant coating on said first side of said substrate that possesses a friction coefficient of 0.5 or lower and (3) a magnetic coating layer on said second side of said substrate, said film also having a surface roughness of 0.01 .mu.m or less, and said substrate being free of inorganic particles, said outer coating comprising a modified polymer obtained by aqueous-phase radical polymerization of at least one methacrylic or acrylic monomer in the presence of a water-dispersible polyester of at least one aromatic dicarboxylic acid and at least one aliphatic diol, containing a plurality of sulfonyloxy groups of general formula:
- (--SO.sub.3 --).sub.n M (I)
- in which n is equal to 1 or 2, and M denotes a hydrogen atom, an alkali or alkaline-earth metal, an ammonium cation or a quaternary ammonium cation.
A magnetic recording material comprising an oriented polyester film including a ventral face and a dorsal face, a magnetic coating applied to the ventral face and, applied on at least the dorsal face, an outer coating possessing a friction coefficient of 0.5 or less that imparts slip and abrasion resistance to the recording material, said polyester film being free from inorganic particles and having a surface roughness of 0.01 .mu.m or less and said coating that imparts slip and abrasion resistance comprising a modified polymer obtained by aqueous phase radical polymerization of at least one acrylic monomer in the presence of a water-dispersible polyester of at least one aromatic dicarboxylic acid and at least one aliphatic diol, containing a plurality of sulphonyloxy groups of general formula:
- (--SO.sub.3 --).sub.n M (I)
- in which n is equal to 1 or 2, and M denotes a hydrogen atom, an alkali or alkaline-earth metal, an ammonium cation or a quaternary ammonium cation.
Dependencies are inferred from the claim text.