US4818581A
Expired / Lapsed
US
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Biaxially oriented polyester film
Assignee: Teijin Ltd
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Filing: 1987-08-26
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Granted: 1989-04-04
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Expires: 2007-08-26
Abstract
Abstract A biaxially oriented polyester film formed from an intimate mixture comprising (1) an aromatic polyester, and (2) 0.01 to 4% by weight, based on the aromatic polyester, of spherical fine particles of silica having (a) an average particle diameter of 0.05 to 4 μm, (b) a particle diameter ratio, defined by the ratio of maximum diameter of minimum diameter, of from 1.0 to 1.2, and (c) a relative standard deviation (σ) of particle size, of up to 0.5. A biaxially oriented polyester film formed from an intimate mixture comprising (1) an aromatic polyester, (2) 0.005 to 3% by weight, based on the aromatic polyester, of spherical fine particles of silica having the same properties as the above-mentioned (a), (b) and (c), and (3) 0.005 to 3% by weight, based on the aromatic polyester, of inert fine particles having an average particle diameter of 0.01 to 3 μm and not exceeding the average particle diameter of the spherical fine particles of silica. The biaxially oriented films are useful for a magnetic recording medium.
Inventors
- 👤 Hideo Katoh
- 👤 Hisashi Hamano
- 👤 Kinji Hasegawa
- 👤 Yoshihiro Noumi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 17:50
CPC Classifications
C; C08; C08L; C08L67/00; C08J; C08J5/00; C08J5/18; C08K; C08K3/00; C08K3/34; C08K3/36; C08J2367/00; C08J2367/02; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/24; Y10T428/24355; Y10T428/24372; Y10T428/29; Y10T428/2982; Y10T428/31504; Y10T428/31786
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
160 words
A biaxially oriented polyester film formed from an intimate mixture comprising (1) an aromatic polyester, and (2) 0.01 to 4% by weight, based on the aromatic polyester, of spherical fine particles of silica having (a) an average particle diameter of 0.05 to 4 μm, (b) a particle diameter ratio, defined by the ratio of maximum diameter to minimum diameter, of from 1.0 to 1.2, and (c) a relative standard deviation (σ) of particle size, defined by the following equation ##EQU12## wherein D i is the diameter (μm) of the equivalent circular area of each of the particles, D is an average value (μm) of the diameter of the equivalent circular area defined by the following equation ##EQU13## and n is the number of the particles, with the proviso that the diameter of the equivalent circular area denotes the diameter of each particle calculated when it is assumed that each particle is of a true spherical shape, of up to 0.5.
Claim 2
Dependent Claim
160 words
A biaxially oriented polyester film formed from an intimate mixture comprising (1) an aromatic polyester, and (2) 0.01 to 4% by weight, based on the aromatic polyester, of spherical fine particles of silica having (a) an average particle diameter of 0.05 to 4 μm, (b) a particle diameter ratio, defined by the ratio of maximum diameter to minimum diameter, of from 1.0 to 1.2, and (c) a relative standard deviation (σ) of particle size, defined by the following equation ##EQU12## wherein D i is the diameter (μm) of the equivalent circular area of each of the particles, D is an average value (μm) of the diameter of the equivalent circular area defined by the following equation ##EQU13## and n is the number of the particles, with the proviso that the diameter of the equivalent circular area denotes the diameter of each particle calculated when it is assumed that each particle is of a true spherical shape, of up to 0.5.
Claim 3
Dependent Claim
30 words
The film of claim 1 wherein the aromatic polyester is derived from an aromatic dicarboxylic acid as a main acid component and an aliphatic glycol as a main glycol component.
Claim 4
Dependent Claim
22 words
The film of claim 1 wherein the spherical fine particles of silica have an average particle diameter of 0.1 to 2 μm.
Claim 5
Dependent Claim
22 words
The film of claim 1 wherein the spherical fine particles of silica have a particle diameter ratio of from 1.0 to 1.15.
Claim 6
Dependent Claim
25 words
The film of claim 1 wherein the spherical fine particles of silica have a relative standard deviation (σ) of particle size of up to 0.3.
Claim 7
Dependent Claim
25 words
The film of claim 1 wherein the spherical fine particles of silica have a relative standard deviation (σ) of particle size of up to 0.12.
Claim 8
Dependent Claim
26 words
The film of claim 1 wherein the amount of the spherical fine particles of silica is 0.05 to 2% by weight based on the aromatic polyester.
Claim 9
Dependent Claim
107 words
The film of claim 1 wherein when the surface of the film is observed under an electron microscope, protrusions attributed to the spherical fine particles of silica are seen; when the surface of the film is ion-etched and then observed under an electron microscope, the spherical silica particles are directly seen, and in this observation, the adjoining spherical silica particles are seen to be in direct contact with each other or interrupted by a void space, and that only up to 10 protrusions among 100 arbitrarily selected protrusions on the film surface before ion etching have a group of spherical fine silica particles having the aforesaid relation.
Claim 10
Dependent Claim
199 words
A biaxially oriented polyester film formed from an intimate mixture comprising (1) an aromatic polyester, (2) 0.005 to 3% by weight, based on the aromatic polyester, of spherical fine particles of silica having (a) an average particle diameter of 0.05 to 4 μm, (b) a particle diameter ratio, defined by the ratio of maximum diameter to minimum diameter, of from 1.0 to 1.2, and (c) a relative standard deviation (σ) of particle size, defined by the following equation ##EQU14## wherein D i is the diameter (μm) of the equivalent circular area of each of the particles, D is an average value (μm) of the diameter of the equivalent circular area defined by the following equation ##EQU15## and n is the number of the particles, with the proviso that the diameter of the equivalent circular area denotes the diameter of each particle calculated when it is assumed that each particle is of a true spherical shape, of up to 0.5, and (3) 0.005 to 3% by weight, based on the aromatic polyester, of inert fine particles having an average particle diameter of 0.01 to 3 μm and not exceeding the average particle diameter of the spherical fine particles of silica.
Claim 11
Dependent Claim
199 words
A biaxially oriented polyester film formed from an intimate mixture comprising (1) an aromatic polyester, (2) 0.005 to 3% by weight, based on the aromatic polyester, of spherical fine particles of silica having (a) an average particle diameter of 0.05 to 4 μm, (b) a particle diameter ratio, defined by the ratio of maximum diameter to minimum diameter, of from 1.0 to 1.2, and (c) a relative standard deviation (σ) of particle size, defined by the following equation ##EQU14## wherein D i is the diameter (μm) of the equivalent circular area of each of the particles, D is an average value (μm) of the diameter of the equivalent circular area defined by the following equation ##EQU15## and n is the number of the particles, with the proviso that the diameter of the equivalent circular area denotes the diameter of each particle calculated when it is assumed that each particle is of a true spherical shape, of up to 0.5, and (3) 0.005 to 3% by weight, based on the aromatic polyester, of inert fine particles having an average particle diameter of 0.01 to 3 μm and not exceeding the average particle diameter of the spherical fine particles of silica.
Claim 12
Dependent Claim
14 words
The film of claim 9 wherein the inert fine particles are internally deposited particles.
Claim 13
Dependent Claim
14 words
The film of claim 9 wherein the inert fine particles are externally added particles.
Claim 14
Dependent Claim
24 words
A magnetic recording medium comprising the biaxially oriented film of claim 1 and a magnetic layer on one or both surfaces of the film.
Claim 15
Dependent Claim
24 words
A magnetic recording medium comprising the biaxially oriented film of claim 9 and a magnetic layer on one or both surfaces of the film.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-04-03 | 1992-10-03 | 1993-04-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-04-03 | 1996-10-03 | 1997-04-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-04-03 | 2000-10-03 | 2001-04-04 | $7700.00 | Window Closed / Lapsed |