Biaxially oriented polyester film

JP7871528B2Active Publication Date: 2026-06-09TORAY INDUSTRIES INC
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Patent Information

Authority / Receiving Office
JP · JP
Patent Type
Patents
Current Assignee / Owner
TORAY INDUSTRIES INC
Filing Date
2021-09-14
Publication Date
2026-06-09

AI Technical Summary

Benefits of technology

【0013】 本発明の二軸配向ポリエステルフィルムは、スリット性、低温低湿度、低温高湿度、高温低湿度、高温高湿度の全ての温湿度領域での寸法安定性、かつ優れた表面平滑性に優れた二軸配向ポリエステルフィルムであって、磁気記録媒体、特に次世代データテープとした際に平滑な磁性層を有すると共に温度や湿度の環境変化や保存による寸法変化が小さく、ミッシングパルスなどのエラー欠点の発生が抑制された高密度磁気記録媒体となる二軸配向ポリエステルフィルムを得ることができる。

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Abstract

To stably provide a biaxially oriented polyester film which has excellent dimensional stability in all temperature and humidity ranges of low temperature and low humidity, low temperature and high humidity, high temperature and low humidity, and high temperature and high humidity, and satisfies both of excellent surface smoothness and slitting property.SOLUTION: A biaxially oriented polyester film where, on at least one outermost layer surface (face B), the number of projections with a height of 50 nm or more is 50,000 / mm2 or less, the number of projections with a height of 100 nm or more is 15,000 / mm2 or less, and a surface average roughness SaB of the layer is larger than the surface average roughness SaA of another outermost surface (face A).SELECTED DRAWING: None
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Claims

1. A biaxially oriented polyester film containing polyethylene terephthalate and polyetherimide, with at least one outermost layer (layer B) surface (surface B) having 50,000 protrusions / mm² with a height of 50 nm or more. ２ Below, the number of protrusions with a height of 100 nm or more is 15,000 per mm. ２ The biaxially oriented polyester film is as follows, wherein the particles contained in layer B are spherical particles selected from organic particles and / or colloidal silica, and the spherical particles have an average primary particle diameter of 0.1 to 0.2 μm and a particle content of 0.05 to 0.2 mass%, or an average primary particle diameter greater than 0.2 μm and 0.3 μm or less and a particle content of 0.005 to 0.05 mass%, and the average surface roughness SaB of the layer is greater than the average surface roughness SaA of the surface (A side) of the other outermost layer (layer A), and the moisture expansion coefficient in the width direction is 4.5 to 6.5 ppm / %RH.

2. On the outermost layer (layer B) surface (surface B), the number of protrusions with a height of 40 nm or more is 70,000 per mm. ２ The biaxially oriented polyester film according to claim 1, which is as follows:

3. On the outermost layer (layer B) surface (surface B), the number of protrusions with a height of 30 nm or more is 0.5 million to 100,000 per mm. ２ The biaxially oriented polyester film according to claim 1 or 2, which is as follows:

4. On the outermost layer (layer B) surface (surface B), the number of protrusions with a height of 30 nm or more is 15,000 to 100,000 per mm. ２ The biaxially oriented polyester film according to any one of claims 1 to 3, which is as follows:

5. On the outermost layer (layer B) surface (surface B), the number of protrusions with a height of 1 nm or more and less than 10 nm is 1 million per mm. ２ The biaxially oriented polyester film according to any one of claims 1 to 4.

6. A biaxially oriented polyester film according to any one of claims 1 to 5, wherein the coefficient of thermal expansion in the width direction is -3.0 to 4.0 ppm / °C or less.

7. A biaxially oriented polyester film according to any one of claims 1 to 6, used as a base film for a magnetic recording medium in a coated digital recording system.