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EP0345644A2 Expired / Lapsed EP ⏱️ 0.0 years remaining

Polyester film for magnetic recording media

Assignee: Mitsubishi Chemical Corp
•
Filing: 1989-06-01
•
Granted: —
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Expires: 2009-06-01
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Abstract

Abstract Disclosed in this invention is a polyester film for magnetic recording media, containing 0.05 to 5% by weight of inactive inorganic particles (A) having a Mohs hardness of 6 or above and an average particle size of 0.005 to 1.0 µm and 0.01 to 2.0% by weight of inactive particles (B) having an average particle size which is greater than that of the particles (A) and in the range of 0.1 to 3.0 µm, the polyester film having an intrinsic viscosity in the range of 0.52 to 0.65. The polyester film of this invention is excellent in abrasion resistance, scuff resistance and slitting qualities and useful as a base film for magnetic recording media.

Inventors

  • 👤 Seiji Sakamoto
  • 👤 Chikakazu Kawaguchi
  • 👤 Yoshio Meguro
  • 👤 Takashi Harada
  • 👤 Toshifumi Takisawa

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-11-02 11:11
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/73; G11B5/739; G11B5/73923; G11B5/73937; C; C08; C08J; C08J5/00; C08J5/18; C08K; C08K3/00; C08K3/18; C08K3/20; C08K3/22; C08L; C08L67/00; G11B5/733; C08J2367/00; C08K2003/2227; C08K2201/00; C08K2201/002; C08K2201/005; C08K2201/009; Y; Y10; Y10T; Y10T428/00; Y10T428/24; Y10T428/24942

Claims Analysis

Total Claims: 8
Claim 1
Independent Claim 83 words
A polyester film for magnetic recording media, containing 0.05 to 5% by weight of inactive inorganic particles (A) having a Mohs hardness of 6 or above and an average particle size of 0.005 to 1.0 µm and 0.01 to 2.0% by weight of inactive particles (B) having an average particle size which is greater than that of said particles (A) and in the range of 0.1 to 3.0 µm, the polyester film having an intrinsic viscosity in the range of 0.52 to 0.65.
Claim 2
Dependent Claim 83 words
A polyester film for magnetic recording media, containing 0.05 to 5% by weight of inactive inorganic particles (A) having a Mohs hardness of 6 or above and an average particle size of 0.005 to 1.0 µm and 0.01 to 2.0% by weight of inactive particles (B) having an average particle size which is greater than that of said particles (A) and in the range of 0.1 to 3.0 µm, the polyester film having an intrinsic viscosity in the range of 0.52 to 0.65.
Claim 3
Dependent Claim 21 words
A polyester film according to claim 1, wherein the inactive inorganic particles (A) are particles of δ-type or γ-type aluminum oxide.
Claim 4
Dependent Claim 18 words
A polyester film according to claim 2, wherein the inactive particles (B) are particles of a heat-resistance polymer.
Claim 5
Dependent Claim 26 words
A polyester film according to claim 2, wherein the inactive particles (B) are deposited particles which separate out in the course of the polyester producing process.
Claim 6
Dependent Claim 26 words
A polyester film according to any of claims 1 to 4, wherein the refractive index of the film in its thickness direction is 1.492 or above.
Claim 7
Dependent Claim 38 words
A polyester film according to any of claims 1 to 4, wherein the thickness of the film is 12.0 µm or less and the F-5 value of the film in the machine direction is 12.0 kg/mm² or greater.
Claim 8
Dependent Claim 63 words
A polyester film according to any of claims 1 to 4, wherein the double-refractive index Δn of the film defined by the following formula (1): Δn = n TD - n MD (1) wherein n TD is refractive index of the film in the transverse direction, and n MD is refractive index of the film in the machine direction, is 0.010 or above.

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