Patent US4798759A successfully refreshed from Google Patents.
US4798759A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Multi-layer polyester film for magnetic tape
Assignee: Hoechst AG
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Filing: 1987-03-13
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Granted: 1989-01-17
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Expires: 2007-03-13
Abstract
Abstract A coextruded, biaxially draw-oriented, multi-layer polyester film as a base film for magnetic tape is described, whose characteristics are that the total thickness of the multi-layer film is no more than 10 μm, the surface roughness of the base film on the side intended for the application of an information-carrying coating has an R a value (DIN 4768) of less than or equal to 0.010 μm and the surface roughness of the opposite side of the base film which is not intended for application of an information-carrying coating, has an R a value of greater than 0.010 μm and that the film has an E-modulus in the machine direction of greater than or equal to 6500 N/mm 2 .
Inventors
- 👤 Hermann Dallman
- 👤 Hartmut Hensel
- 👤 Werner Schafer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 15:20
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/84; G11B5/62; G11B5/73; G11B5/739; G11B5/73923; G11B5/73927; G11B5/73931; G11B5/73935; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/25; Y10T428/254; Y10T428/256; Y10T428/259; Y10T428/31504; Y10T428/31786
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
114 words
A thin, coextruded, biaxially oriented multilayer film having a superior modulus of elasticity comprising (i) a first polyester film layer whose surface roughness R a is 0.010 micron or less; (ii) a second polyester film layer whose surface roughness R a is greater than 0.010 micron, said polyester film containing (a) from 0.01 to 1% by weight of particles having an average particle size of from 0.001 to five microns and (b) from 0.01 to 5 weight percent of a nucleating agent, with the proviso that said film have a thickness not greater than 10 microns and yet has a modulus of elasticity in the machine direction of at least 6,500 N/mm 2 .
Claim 2
Dependent Claim
114 words
A thin, coextruded, biaxially oriented multilayer film having a superior modulus of elasticity comprising (i) a first polyester film layer whose surface roughness R a is 0.010 micron or less; (ii) a second polyester film layer whose surface roughness R a is greater than 0.010 micron, said polyester film containing (a) from 0.01 to 1% by weight of particles having an average particle size of from 0.001 to five microns and (b) from 0.01 to 5 weight percent of a nucleating agent, with the proviso that said film have a thickness not greater than 10 microns and yet has a modulus of elasticity in the machine direction of at least 6,500 N/mm 2 .
Claim 3
Dependent Claim
20 words
The film of claim 1 wherein said first layer has a surface roughness R a not greater than 0.005 micron.
Claim 4
Dependent Claim
14 words
The film of claim 1 wherein said first layer comprises a blend of polyesters.
Claim 5
Dependent Claim
12 words
The film of claim 1 wherein said first layer comprises polyethylene terephthalate.
Claim 6
Dependent Claim
14 words
The film of claim 1 wherein said second layer comprises a blend of polyesters.
Claim 7
Dependent Claim
12 words
The film of claim 1, wherein said second layer comprises polyethylene terephthalate.
Claim 8
Dependent Claim
12 words
The film of claim 1 wherein said nucleating agent comprises sodium montanate.
Claim 9
Dependent Claim
27 words
The film of claim 1 wherein said particles are selected from the group comprising barium sulfate, a crosslinked acrylate, calcium carbonate, silicon dioxide, kaolin, and titanium dioxide.
Claim 10
Dependent Claim
14 words
The film of claim 8 wherein said particles comprise crosslinked acrylate or barium sulfate.
Claim 11
Dependent Claim
155 words
A process for the manufacture of thin, coextruded polyester film having a superior modulus of elasticity comprising (i) melting in separate extruders a first polyester resin which does not contain any particles and a second polyester resin which contains (a) from 0.01 to 1% by weight of particles having an average particle size of from 0.001 to five microns and (b) from 0.01 to 5 weight percent of a nucleating agent, (ii) simultaneously coextruding said first and second polyester resins through a die onto a cooling drum, thereby forming cast coextruded polyester sheet, (iii) orienting and subsequently heat setting said cast coextruded polyester sheet to produce a biaxially oriented multilayer polyester film having a E-modulus in the machine direction of at least 6,500 N/mm 2 , a thickness not greater than 10 microns, a surface roughness of 0.010 micron or less on one surface and a surface roughness greater than 0.010 micron on the opposite.
Claim 12
Dependent Claim
155 words
A process for the manufacture of thin, coextruded polyester film having a superior modulus of elasticity comprising (i) melting in separate extruders a first polyester resin which does not contain any particles and a second polyester resin which contains (a) from 0.01 to 1% by weight of particles having an average particle size of from 0.001 to five microns and (b) from 0.01 to 5 weight percent of a nucleating agent, (ii) simultaneously coextruding said first and second polyester resins through a die onto a cooling drum, thereby forming cast coextruded polyester sheet, (iii) orienting and subsequently heat setting said cast coextruded polyester sheet to produce a biaxially oriented multilayer polyester film having a E-modulus in the machine direction of at least 6,500 N/mm 2 , a thickness not greater than 10 microns, a surface roughness of 0.010 micron or less on one surface and a surface roughness greater than 0.010 micron on the opposite.
Claim 13
Dependent Claim
12 words
The process of claim 10 wherein said nucleating agent is sodium montanate.
Claim 14
Dependent Claim
26 words
The process of claim 10 wherein heat setting is performed within a temperature range between T g +70° C. and the melting point of the polymer.
Claim 15
Dependent Claim
20 words
The process of claim 12 wherein said heat setting is performed within a time interval of 0.5 to 100 seconds.
Claim 16
Dependent Claim
36 words
The process of claim 10 wherein said orienting is performed by stretching the film in the machine direction and in the transverse direction with an overall draw ratio lying within the range from 1.05 to 9.0.
Claim 17
Dependent Claim
13 words
The process of claim 14, wherein stretching is performed in a two-stage process.
Claim 18
Dependent Claim
13 words
The process of claim 14 wherein stretching is performed in a multi-stage process.
Claim 19
Dependent Claim
14 words
The process of claim 14 wherein stretching is performed in a simultaneous stretching process.
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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) | 1992-01-17 | 1992-07-18 | 1993-01-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-01-17 | 1996-07-18 | 1997-01-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-01-17 | 2000-07-18 | 2001-01-17 | $7700.00 | Window Closed / Lapsed |