Loading patent…
AssigneeToda Kogyo Corporation
InventorsKazuyuki Hayashi, Keisuke Iwasaki, Hiroko Morii, Mineko Ohsugi
Estimating the term…
Non-magnetic composite particles composed of non-magnetic core particles having an average particle size of 0.01 to 0.3 μm, and inorganic fine particles having an average particle size of 0.001 to 0.07 μm. The fine particles are present in an amount of 0.1 to 20% by weight based on the weight of the non-magnetic particles are on the surface of each non-magnetic particle, and are fixed or anchored on the surface of each non-magnetic particle through a silicon compound The non-magnetic composite particles have a high polishing effect and a high dispersibility, and are useful as a non-magnetic undercoat layer for a magnetic recording medium.
Non-magnetic composite particles comprising:
Dependencies are inferred from the claim text.
Drawings are temporarily unavailable. Open the PDF at USPTO
From the US filing history. Foreign family members aren’t listed.
Backward citations are indexed for grants only.
Treatment of specific inorganic materials other than fibrous fillers ; Preparation of carbon black: compounds of iron
Nanotechnology for materials or surface science
Base layers , i.e. all non-magnetic layers lying under a lowermost magnetic recording layer, e.g. including any non-magnetic layer in between a…:…
Depicted by an image: obtained by SEM
Term end not estimated
The present invention relates to non-magnetic composite particles, a process for producing the non-magnetic composite particles, and a magnetic recording medium using the non-magnetic composite particles. More particularly, the present invention relates to non-magnetic composite particles having a high polishing effect and a high dispersibility, a magnetic recording medium which is provided with a non-magnetic undercoat layer using the above non-magnetic composite particles, and has an excellent durability and a sufficient surface smoothness, a non-magnetic substrate containing the non-magnetic composite particles, and a process for producing the non-magnetic composite particles.
With the recent tendency toward miniaturization and weight-reduction of video or audio magnetic recording and reproducing apparatuses as well as prolonged recording time of these apparatuses, magnetic recording media such as magnetic tapes or magnetic discs have been strongly required to have a high performance, namely, high recording density, high output characteristics such as, especially, improved frequency characteristics, low noise level or the like.
In particular, recent video tapes have been also required to exhibit higher picture quality, so that the frequencies of carrier signals recorded thereon are shifted to shorter wavelength region (short wave-recording) as compared to those used for conventional video tapes. As a result, the magnetization depth from the surface of the magnetic tape has become remarkably shallow.
The present invention is described in more detail by Examples and Comparative Examples, but the Examples are only illustrative and, therefore, not intended to limit the scope of the present invention.
Various properties were measured by the following methods.
(1) The average major axial diameter and average minor axial diameter of particles are respectively expressed by the average value obtained by measuring about 350 particles which were sampled from a micrograph obtained by magnifying an original electron micrograph (×30,000) by four times in each of longitudinal and transverse directions.