Patent US4812351A successfully refreshed from Google Patents.
US4812351A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic recording medium
Assignee: Fujifilm Holdings Corp
•
Filing: 1988-05-03
•
Granted: 1989-03-14
•
Expires: 2008-05-03
Abstract
Abstract A magnetic recording medium is described, comprising a non-magnetic support having a surface roughness of 0.02 μm or less, a magnetic layer on the surface of the support and a backing layer on a surface of the support opposite to the surface on which the magnetic layer is formed, wherein the backing layer is formed by exposing to radiation a layer comprising (A) non-magnetic particles and (B) a radiation polymerizable compound.
Inventors
- 👤 Tsutomu Okita
- 👤 Masashi Aonuma
- 👤 Hiroshi Hashimoto
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 22:58
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/73; G11B5/735; G11B5/7356; G11B5/7358; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/24; Y10T428/24355; Y10T428/26; Y10T428/263; Y10T428/264; Y10T428/265
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
181 words
A magnetic recording medium comprising a non-magnetic support with opposing surfaces carrying a magnetic layer and backing layer both having a surface roughness of 0.02 μm or less, the magneti layer on one surface of the support, and the backing layer being on the surface of the support opposite to the surface on which the magnetic layer is formed, wherein the backing layer is formed by exposing to radiation a layer comprising (A) non-magnetic particles having an average particle size of 0.8 μm or less and (B) a binder comprising a radiation exposed radiation polymerizable compound wherein the weight ratio of non-magnetic particles to the binder is from 4/1 to 0.01/1 and wherein the radiaton polymerizable compound is used in an amount of 20 wt % or more based on the total weight of the binder wherein said magnetic layer is coated on the non-magnetic support and, dried, and then subjected to surface smoothin by calendering, whereafter the backing layer is coated and then the resulting assembly is subjected to said exposing the radiation to thereby obtain said magnetic recording medium.
Claim 2
Dependent Claim
181 words
A magnetic recording medium comprising a non-magnetic support with opposing surfaces carrying a magnetic layer and backing layer both having a surface roughness of 0.02 μm or less, the magneti layer on one surface of the support, and the backing layer being on the surface of the support opposite to the surface on which the magnetic layer is formed, wherein the backing layer is formed by exposing to radiation a layer comprising (A) non-magnetic particles having an average particle size of 0.8 μm or less and (B) a binder comprising a radiation exposed radiation polymerizable compound wherein the weight ratio of non-magnetic particles to the binder is from 4/1 to 0.01/1 and wherein the radiaton polymerizable compound is used in an amount of 20 wt % or more based on the total weight of the binder wherein said magnetic layer is coated on the non-magnetic support and, dried, and then subjected to surface smoothin by calendering, whereafter the backing layer is coated and then the resulting assembly is subjected to said exposing the radiation to thereby obtain said magnetic recording medium.
Claim 3
Dependent Claim
39 words
A magnetic recording medium as in claim 1, wherein the radiation polymerizable compound is a compound having a polyurethane skeleton, having at least two acryloyl groups in a molecule, and having a molecular weight of from 3,000 to 50,000.
Claim 4
Dependent Claim
21 words
A magnetic recording medium as in claim 1, wherein the surface roughness of the non-magnetic support is 0.015 μm or less;
Claim 5
Dependent Claim
33 words
A magnetic recording medium as in claim 1, wherein the magnetic layer has been prepared by electron irradiatioan of a layer containing an electron beam polymerizable compound as a binder and ferromagnetic particles.
Claim 6
Dependent Claim
31 words
A magnetic recording medium as in claim 7, wherein the electron beam irradiation has been carried out so as to simultaneously polymerize and harden the magnetic layer and the backing layer.
Claim 7
Dependent Claim
23 words
A magnetic recording medium as in claim 1, wherein the average particle size of the non-magnetic particles is from 0.03 to 0.4 μm.
Claim 8
Dependent Claim
22 words
A magnetic recording medium as in claim 2, wherein the radiation polymerizable compound has a molecular weight of from 5,000 to 30,000.
Claim 9
Dependent Claim
23 words
A magnetic recording medium as in claim 1, wherein the weight ratio of non-magnetic particles to a binder is from 3/1 to 0.5/1.
Claim 10
Dependent Claim
32 words
A magnetic recording medium as in claim 1, wherein the radiation polymerizable compound is used in an amount of 40 wt % or more, based on the total weight of the binder.
Claim 11
Dependent Claim
21 words
A magnetic recording medium as in claim 1, wherein the surface roughness of the non-magnetic support is 0.01 μm or less.
Claim 12
Dependent Claim
21 words
A magnetic recording medium as in claim 1, wherein the thickness of the non-magnetic support is from 1 to 30 μm.
Claim 13
Dependent Claim
21 words
A magnetic recording medium as in claim 1, wherein the thickness of the non-magnetic support is from 2 to 20 μm.
References Cited (Backward Citations)
US4337288A
Cited
US4474843A
Cited
US4496626A
Cited
US4560616A
Cited
US4481231A
Cited
US4592942A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-03-13 | 1992-09-12 | 1993-03-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-03-13 | 1996-09-12 | 1997-03-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-03-13 | 2000-09-12 | 2001-03-14 | $7700.00 | Window Closed / Lapsed |