Patent US2751446A successfully refreshed from Google Patents.
EP0097509A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Erasable recording medium comprising a dimer acid polyamide resin
Assignee: Celanese Corp
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Filing: 1983-06-20
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Granted: —
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Expires: 2003-06-20
Abstract
Abstract Provided is an erasable recording medium and a method for recording and erasing same. The erasable recording medium comprises a thermally stable substrate and a polymeric layer deposited on the substrate comprised of a lower molecular weight dimer acid polyamide. Such a recording medium has excellent dimensional and mechanical stability on storage, readily and easily records information and has an ability to be easily and completely erased when erasure is desired.
Inventors
- 👤 James E. Kuder
- 👤 Anthony J. East
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-23 11:23
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/24; G11B7/241; G11B7/242; G11B7/244; G11B7/245
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
47 words
An ablative recording medium, suitable for use with a recording laser, comprising a thermally stable substrate and a recording polymer layer coated thereon, characterised in that the polymer layer comprises a dimer acid polyamide having a weight average molecular weight in the range from 2,000 to 20,000.
Claim 2
Dependent Claim
47 words
An ablative recording medium, suitable for use with a recording laser, comprising a thermally stable substrate and a recording polymer layer coated thereon, characterised in that the polymer layer comprises a dimer acid polyamide having a weight average molecular weight in the range from 2,000 to 20,000.
Claim 3
Dependent Claim
79 words
An ablative recording medium, suitable for use with a recording laser, comprising a thermally stable substrate and a recording polymer layer coated thereon, characterised in that the polymer layer comprises a dimer acid polyamide having a surface tension, measured in dynes/cm, and a melt viscosity, measured in poise, in the temperature range of from 140 to 200°C, such that the ratio of said surface tension to melt viscosity at some point within said temperature range is at least 2:1.
Claim 4
Dependent Claim
79 words
An ablative recording medium, suitable for use with a recording laser, comprising a thermally stable substrate and a recording polymer layer coated thereon, characterised in that the polymer layer comprises a dimer acid polyamide having a surface tension, measured in dynes/cm, and a melt viscosity, measured in poise, in the temperature range of from 140 to 200°C, such that the ratio of said surface tension to melt viscosity at some point within said temperature range is at least 2:1.
Claim 5
Dependent Claim
34 words
The recording medium of claim 2 wherein the dimer acid polyamide has a Vicat softening point of from 45 to 120°C and a temperature for the onset of thermal degradation of at least 250°C.
Claim 6
Dependent Claim
43 words
The recording medium of claim 2 or 3 wherein the surface tension and viscosity exhibited by the polymer are such that the ratio of surface tension to viscosity at some point in the temperature range from 140 to 200°C is at least 5:1.
Claim 7
Dependent Claim
28 words
The recording medium of any of claims 2 - 4 wherein the dimer acid polyamide has a weight average molecular weight in the range from 2,000 to 20,000.
Claim 8
Dependent Claim
26 words
The recording medium of claims 1 or 5 wherein the dimer acid polyamide has a weight average molecular weight in the range from 2,500 to 18,000.
Claim 9
Dependent Claim
24 words
The recording medium of claim 6 wherein the dimer acid polyamide has a weight average molecular weight in the range from 3,000 to 16,000.
Claim 10
Dependent Claim
35 words
The recording medium of any of claims 1 - 7 wherein said dimeriacid polyamide polymer layer coated on the substrate further comprises a dye material which is absorptive at the frequency of the recording laser.
Claim 11
Dependent Claim
17 words
The recording medium of any of claims 1 - 8 wherein the substrate comprises glass or polymethylrrethacrylate.
Claim 12
Dependent Claim
32 words
The recording medium of any of claims 1 - 9 wherein the substrate has a top layer adjacent the polymer layer which is a metallised reflective layer, thereby rendering the substrate reflective.
Claim 13
Dependent Claim
15 words
The recording medium of any of claims 1 - 10 wherein the substrate is transparent.
Claim 14
Dependent Claim
20 words
The recording medium of any of claims 1 - 7 wherein the recording medium is'in the form of a disc.
Claim 15
Dependent Claim
28 words
An optically readable and erasable information disc being the recording medium of claim 12 wherein the polymer layer is an information track comprising a succession of spaced pits.
Claim 16
Dependent Claim
113 words
An erasable information medium, useful with play back aparatus employing playback beam of light of a predetermined frequency, said medium comprising a substrate having a light reflective surface and a polymer layer comprising a dimer acid polyamide having a weight average molecular weight in the range from 2,000 to 20,000, with an information track comprising a succession of pits formed in said dimer acid polyamide layer, wherein the thickness of said dimer acid polyamide 'layer in all regions of the information medium other than those occupied by said pits is a given thickness chosen so as to establish a destructive reflection condition for light directed toward said information medium at the predetermined frequency.
Claim 17
Dependent Claim
113 words
An erasable information medium, useful with play back aparatus employing playback beam of light of a predetermined frequency, said medium comprising a substrate having a light reflective surface and a polymer layer comprising a dimer acid polyamide having a weight average molecular weight in the range from 2,000 to 20,000, with an information track comprising a succession of pits formed in said dimer acid polyamide layer, wherein the thickness of said dimer acid polyamide 'layer in all regions of the information medium other than those occupied by said pits is a given thickness chosen so as to establish a destructive reflection condition for light directed toward said information medium at the predetermined frequency.
Claim 18
Independent Claim
52 words
A method of recording information in a thin film deposited on a relatively thick substrate by irradiating the film with a laser beam in accordance with said information to form pits in the film, characterised in that the film comprises dimer acid polyamide as defined in any of claims 1 - 7.
Claim 19
Independent Claim
31 words
A method of erasing a deformation information pattern applied to the recording medium of any of claims 1 - 12 which comprises heating the polymer layer to erase the deformation pattern.
Claim 20
Dependent Claim
29 words
The method of claim 16 wherein the polymer layer is heated to a temperature in the range from 140 to 200°C sufficient to effect levelling of the polymer layer.
Claim 21
Dependent Claim
29 words
The method of claim 16 or 17 wherein the polymer layer is heated during erasure to a temperature at least 50°C below the temperature used in recording the information.
References Cited (Backward Citations)
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