Magnetic recording media and thermoplastic polyurethane resins therefor

• US 6,545,119 B2
• Filed: 03/07/2000
• Issued: 04/08/2003
• Est. Priority Date: 03/08/1999
• Status: Expired due to Fees

• Current Assignee: Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Original Assignee: Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Inventors: Yatsuka, Takeshi, Sugitawa, Chikara, Doi, Kuniyuki, Kizumoto, Hirotoshi
• Primary Examiner(s): GORR, RACHEL F
• Application Number:
  US09/520,204
• Publication Number:
  US 20030022022A1
• Time in Patent Office: 1,127 Days
• Field of Search: 528/83, 528/71, 525/440
• US Class Current: 528/71
• CPC Class Codes: C08G 18/4202 Two or more polyesters of different physical or chemical nature C08G18/44 takes precedence
• CPC Class Codes: C08G 18/4211 derived from aromatic dicarboxylic acids and dialcohols
• CPC Class Codes: C08G 18/4238 derived from dicarboxylic acids and dialcohols
• CPC Class Codes: C09D 175/06 from polyesters
• CPC Class Codes: G11B 5/7021 containing a polyurethane or a polyisocyanate

Abstract

A magnetic recording medium possessing a magnetic layer formed by application onto a non-magnetic support, of a magnetic coating containing magnetic particles dispersed in a binder which contains a polyurethane resin, together with carbon black particles at 5% by weight or higher, based on the weight of the magnetic particles. The polyurethane resin to be used herein is composed of: (a) a polyester polyol having a molecular weight of 2000 or lower and containing at least one selected from the group consisting of aromatic dibasic acids and alicyclic dibasic acids at a ratio of 90 mol % or higher of acid components; (b) a high molecular weight polyol having a molecular weight of 5000 or lower, which is at least one selected from the group consisting of (b1) polyester polyols each containing an aliphatic dibasic acid at a ratio of 90 mol % or higher of acid components, (b2) polylactones, (b3) polyester polyols, and (b4) polycarbonate polyols; (c) an organic diisocyanate compound; and (d) an optional compound having a molecular weight of 500 or lower and containing at least two functional groups in one molecule, which are reactive with isocyanate groups.

Claims

1. A thermoplastic resin for use in recording media, comprising the product of the reation in a molten state of a polyester polyol (component A), component A comprising at least one component selected from the group consisting of a sulfuric acid metal salt group containing dicarboxylic acids and a sulfuric acid metal salt group containing glycols, and a low molecular weight diol (component B) having a molecular weight of 500 or lower with an organic diisocyanate compound, said component B being at least one selected from the group consisting of diols having a molecular weight of 200 or higher and diols in liquid form at 20°

C., wherein at least 80 mol % of the dicarboxylic acid component of component A is a dicarboxylic acid selected from the group consisting of isophthalic acid, o-phthalic acid, phthalic anhydride, 1-3-cyclohexanedicarboxylic acid, and 1,2-cyclohexanedicarboxylic acid.