Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Structurally defined
Reexamination Certificate
2000-05-23
2001-10-16
Schilling, Richard L. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Structurally defined
C430S140000, C430S523000, C430S531000, C430S961000, C360S131000, C360S134000, C427S131000, C428S900000, C508S450000, C508S451000
Reexamination Certificate
active
06303280
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a transparent magnetic recording medium, which is excellent in a state of coated surface and magnetic input/output performance.
BACKGROUND OF THE INVENTION
A magnetic recording layer of a magnetic recording medium, such as an audiotape, a videotape, and a floppy disc, contains a high content (coated amount) of magnetic substance, which results in lack of light-permeability, even though high magnetic output (reading) capability can be attained. Consequently, the above-described magnetic recording layer techniques cannot be applied, as it is, onto the printing surface of a magnetic card or onto a photographic film. U.S. Pat. No. 5,491,051 describes photographic elements that exhibit excellent magnetic and photographic characteristics, and that are capable of repeated use.
A difficulty, however, arises for these photographic elements. That is, the photographic elements are not satisfactorily reliable in recording or reading of incorporated magnetic recording various information when incorporated magnetic recorded information is used repeatedly or used as conditions for development or printing. Such incorporated magnetic recording information utilized includes the date of photographing, weather, conditions for illumination, conditions at the time of photographing (e.g. the ratio of reduction to enlargement), the number of leaves for reprinting, an area to be zoomed, and some messages. Further, transparent magnetic layer-related techniques are described in JP-A-4-214217 (“JP-A” means unexamined published Japanese patent application), JP-A-6-161033, U.S. Pat. Nos. 5,496,687, 5,432,050, 5,436,120, and U.S. Pat. No. 5,434,037.
Practically, for example, when a transparent magnetic recording medium is also given a function as a photographic element (photographic light-sensitive material), dirt substances (hereinafter referred to as dirt) easily deposit on a magnetic head. The dirt is mainly composed of a dried solid of the developing solution, and it is very adhesive to things. The above-described adhesive dirt, which is not usually formed for an ordinary magnetic recording medium, becomes adhered to and deposits on a magnetic head from the medium, to make the precise contact of a magnetic layer with the head considerably deteriorated. Further, so-called spacing loss occurs by the dirt, which results in an error in reading of the magnetic recorded information. Even if alumina abrasives, which are used for an ordinary magnetic recording medium, are used to clean the head dirtied, the dried solid of the developing solution cannot be sufficiently prevented from adhering onto the magnetic head in a conventional method. Further, when the amount of the alumina abrasives to be used is increased, or a larger particle of alumina abrasives is used, a new problem arises. Dirt-removal is not improved sufficiently, and undesirably the transparency of the medium extremely decreases, which is disadvantageous to photographic use, and the life (duration) of the magnetic head is drastically shortened.
Further, in order to remove deposited dirt owing to dried-up ingredients of a developing solution, it is known to coat an overcoat solution containing particles onto the surface of a magnetic recording medium. In this case, in order to incorporate spherical particles in the overcoat solution and to hold them in a magnetic recording layer as an underlayer (i.e. a layer below the overcoat layer), it is necessary to incorporate, in the overcoat solution, a solvent that is able to dissolve the underlayer. However, at the time of coating the overcoat solution, interaction (aggregation) between a binder, which is dissolved into the solvent out of the underlayer, and a lubricant wax dispersion incorporated in the overcoat solution, occurs, and consequently the state of coated surface deteriorates. Particularly, in order to sufficiently bury spherical particles into the underlayer, it is necessary to increase the ratio of the solvent employed to dissolve the underlayer, but the tendency of occurrence of such as the above-mentioned problems is becoming stronger. Thus, if the state of coated surface deteriorates, not only is the appearance of the product made worse, but also contact (hit) with a magnetic head becomes uneven, so that fundamental characteristics (electromagnetic conversion characteristics) of the magnetic recording medium are affected badly. Accordingly, there is a need to improve the above-mentioned problems.
SUMMARY OF THE INVENTION
That is, an object of the present invention is to provide a transparent magnetic recording medium that excels in the state of coated surface (no unevenness in appearance), and that exhibits excellent magnetic input/output performance.
Other and further objects, features, and advantages of the invention will appear more fully from the following description.
DETAILED DESCRIPTION OF THE INVENTION
The above-described object of the present invention has been attained by the following magnetic recording mediums and light-sensitive material.
(1) A transparent magnetic recording medium comprising at least one magnetic recording layer containing ferromagnetic particles, on a support, wherein an overcoat solution which comprises at least one kind of lubricant wax dispersion and at least one kind of anionic surfactant in an amount of 0.1% to 30%, based on the total weight of the lubricant wax dispersion, is coated on the at least one magnetic recording layer.
(2) A silver halide photographic light-sensitive material having the transparent magnetic recording layer as stated in the above (1).
As preferable embodiments of the present invention, in addition to the above, the following magnetic recording mediums and light-sensitive material can be mentioned.
(3) The transparent magnetic recording medium as stated in the above (1), wherein the lubricant wax dispersion is a higher fatty acid ester-lubricant dispersion.
(4) The transparent magnetic recording medium as stated in the above (1) or (3), wherein the anionic surfactant is allowed to be previously adsorbed on the surface of the dispersed wax lubricant in the lubricant wax dispersion solution.
(5) The transparent magnetic recording medium as stated in any one of the above (1), (3), or (4), wherein the overcoat solution comprises at least one kind of spherical inorganic particles having a Mohs' hardness of 6 to 8 and/or at least one kind of spherical organic high-molecular particles.
(6) The transparent magnetic recording medium as stated in any one of the above (1), (3), (4), or (5), wherein the wax lubricant is previously dispersed by a solvent comprising cyclohexanone and the overcoat solution contains at least diacetone alcohol (DAA) as its solvent and the binder of the magnetic recording layer is diacetyl cellulose (DAC).
(7) The transparent magnetic recording medium as stated in any one of the above (1), (3), (4), (5), or (6), wherein the transparent magnetic recording layer contains inorganic particles having an average primary particle size of from 1 nm to 50 nm in an amount of from 10 mg/m
2
to 200 mg/m
2
.
(8) The transparent magnetic recording medium as stated in any one of the above (1), (3), (4), (5), (6), or (7), wherein the transparent magnetic recording layer contains alumina abrasives having substantially higher particle size than the any average height of the surface protrusion of said spherical inorganic particles and said spherical organic high-molecular particles.
(9) A silver halide photographic light-sensitive material having the transparent magnetic recording layer as stated in any one of the above (3) to (8), which comprises at least one light-sensitive silver halide emulsion layer provided on one side of a support opposite to the transparent magnetic recording layer.
It is effective to locate, at the surface of the medium, spherical inorganic particles having a Mohs' hardness of 6 to 8, preferably monodispersed amorphous (noncrystalline) silica particles or titanium oxide particles, to remove the dirt that is formed when a transparent magne
Arai Tsutomu
Matsunaga Naohiro
Yasuda Tomokazu
Birch & Stewart Kolasch & Birch, LLP
Fuji Photo Film Co. , Ltd.
Schilling Richard L.
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