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1. WO1984000436 - COMPOSITION MAGNETIQUE DE REVETEMENT A BASE D'EAU

Note: Texte fondé sur des processus automatiques de reconnaissance optique de caractères. Seule la version PDF a une valeur juridique

[ EN ]

WHAT IS CLAIMED IS:

1. In an aqueous coating composition for forming a
magnetic recording layer, the improvement comprising the
use of a polyacrylic latex polymer as a dispersant.

2. The aqueous coating composition of claim 1 wherein the polyacrylic latex polymer comprises a terpolymer of styrene and a member selected from the group consisting of butyl acrylate and methylmethacrylate.

3. The aqueous coating composition of claim 2 wherein styrene is present in the polyacrylic latex in an amount between approximately 10-20% by weight and the remaining acrylate is present in the polyacrylic latex in an amount between approxi mately 80-90% by weight.

4. The aqueous coating composition of claim 2 wherein said copolymer is of a molecular weight between approximately 20,000 to 40,000.

5. The aqueous coating composition of claim 1 further comprising a water insoluble polymeric binder having both a hard and a soft component.

6. The aqueous coating composition of claim 5 wherein the hard component comprises a member selected from the group consisting of copolymers and terpolymers of acrylonitrile, ethyl acrylate, butylacrylate, methylmethacrylate and mixtures thereof.

7. The aqueous coating composition of claim 6 wherein the hard component comprises a copolymer of approximately
10-20% by weight of acrylonitrile and approximately 80-90% by weight of a member selected from the group consisting of ethylacrylate and butylacrylate.

8. The aqueous coating composition of claim 6 wherein the hard component comprises a terpolymer of approximately
10-20% by weight of acrylonitrile, approximately 10-25% by weight ethylacrylate, approximately 60-80% by weight butyl acrylate and approximately 10-20% by weight methylmethacrylate.

9. The aqueous coating composition of claim 5 wherein the soft component comprises a polymer emulsion of a polyurethane having a glass transition temperature of between approximately -10ºC to -40ºC.

10. The aqueous coating composition of claim 5 further comprising a flow agent, antifoaming agent, wetting agent and lubricant.

11. The aqueous coating composition of claim 10 wherein said flow agent is an alkyline-soluble emulsion of ethyl acrylate and acrylic acid.

12. The aqueous coating composition of claim 10 wherein said lubricant comprises a member selected from the group consisting of aliphatic and aromatic stearates, silicone oils, perfluoro alkyl polyethers and fluorinated fluids having one of the following structures:



and m xtures thereof .