JPS59172141A - Magnetic transfer sheet - Google Patents

Abstract

PURPOSE:To lower the surface electric resistance of a magnetic layer and to improve the running stability at the time of magnetic transfer without lowering the practical use level of magnetic characteristic and the surface property of the magnetic layer by adding a specific amount of carbon black in specific grain size to the magnetic layer as an antistatic agent. CONSTITUTION:Carbon black of 15-40mum of average grain size is mixed into a magnetic layer to be installed on a non-magnetic supporting body as an antistatic agent at a ratio of 2-5wt% of the magnetic power. When the average grain size is <=15mum, the carbon black is hardly dispersed well and coating is made difficult. In the contrary, when the average grain size is >=40mmu, the surface electric resistance value cannot be lowered sufficiently and, in addition, the surface property of the magnetic layer becomes worse. Therefore, when the carbon black of this invention is used, the surface electric resistance of the magnetic layer can be lowered sharply and no frictional electricity charging due to running occurs, and therefore, the running stability at the time of magnetic transfer is extremely improved. In addition to the above, since no frictional electrification occurs at the time of running as mentioned above, the generation of drop-out and noise is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a magnetic transfer sheet, and in particular provides a magnetic transfer sheet with excellent running properties during magnetic transfer.

Conventional technology In general, magnetic transfer (also called magnetic printing) is a process in which analog signals or digital signals are recorded in advance, so-called master sheets and copy sheets are placed together so that the magnetic layers face each other, and pressure is applied from the outside. A method is adopted in which a transfer magnetic field is applied while the master sheet is brought into close contact with the master sheet, and then the signals recorded on the master sheet are transferred to the copy sheet.

When performing such magnetic transfer, if the surface electrical resistance of the master sheet and copy sheet is high, frictional electrification occurs during running, which not only increases dropouts and discharge noise, but also causes poor running in the magnetic transfer device. (jamming, misalignment, double feeding, etc.).

Purpose The purpose of the present invention was achieved despite the fact that Kazen black was added to the magnetic layer as an antistatic agent.

An object of the present invention is to provide a magnetic transfer sheet in which running stability during magnetic transfer is improved by lowering the surface electrical resistance of a magnetic layer without deteriorating the practical level of magnetic properties or surface properties.Structure: Magnetic transfer sheet of the present invention is magnetic powder on a non-magnetic support,
The present invention is characterized in that a magnetic layer is provided which contains Kazen black having an average particle size of 15 to 40 mμ as a binder and an antistatic agent in an amount of 2 to 5 M relative to the magnetic powder.

In order to achieve the above object, it is necessary that the average particle size of the Kazen black toshi used in the invention be in the range of 15 to 40 mμ, and that the amount used be in the range of 2 to 5% by weight relative to the magnetic material. is. If the average particle diameter is 15 mμ or less, it is very difficult to disperse Kazen black, and
The magnetic paint becomes extremely titanium-tropic, making coating difficult, and if the average particle diameter is 40 mμ or more, the surface electrical resistance value (preferably 10 9 Ω or less) will not be sufficiently lowered, and the surface properties of the magnetic layer will deteriorate.

If the amount used is less than 2vrt of the magnetic material, the surface electrical resistance value will not decrease, and if it is more than 5wt%, the dispersibility of the magnetic paint will be inhibited, and the magnetic properties and surface properties will deteriorate.

The magnetic powder may be iron oxide, chromium dioxide, or metal magnetic powder.

As the t'fc binder, thermoplastic resins, thermosetting resins, reactive resins, etc. can be used alone or in combination. The appropriate amount to be used is about 10 to 200 parts by weight per 100 parts by weight of the magnetic powder. Note that thermoplastic resins include vinyl chloride resin, acrylic resin, and methacrylic resin.

Vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonyl chloride copolymer, (nysdermethanoacrylate-acrylonitrile copolymer), polyvinyl butyral, cellulose acetate butyrate, etc. Examples of thermosetting resins or reactive resins include phenolic resins, epoxy resins, polyurethane cured umotts, reactive acrylic resins, and mixtures of high molecular weight polyester resins and incyanate prepolymers.

In addition to the above-mentioned materials, usual additives such as dispersants, lubricants, and plasticizers can be added to the magnetic layer.

Dispersants include lecithin, higher fatty acids, fatty acids, silicone oil, and fluorocarbon oil.

Metal soap etc. can be used. The appropriate amount to be used is about 1 to 20 parts by weight per 100 parts by weight of the binder.

As a lubricant, silicone oil, higher fatty acid ester,
Examples include higher fatty acid amides, paraffin hydrocarbons, graphite, polyfluoroethylene powder, polyethylene powder, and the like.

The appropriate amount to be used is about 0.2 to 20 parts by weight per 100 parts by weight of the binder.

The plasticizer may be dioctyl phthalate, dibutyl phthalate, etc., and its use fIk is suitably about 5 to 30 parts by weight based on 300 parts by weight of the binder.

To make the magnetic transfer sheet of the present invention, the above-mentioned materials are thoroughly mixed and dispersed in a dispersion machine with a solvent such as toluene or methyl ethyl ketone to form a magnetic paint, and this is applied onto a non-magnetic support such as plastic film paper 5 or synthetic paper. A magnetic layer may be provided by drying. As a dispersing machine, a Zeel 5-mill, a vibration S-mill, a sand mill, a desilver, an attritor, a high-speed mixer, a kneader, etc. are used, but there is no problem in using these in combination. Also, as a coating means, a doctor blade, General means such as a gravure roll, a reverse roll, and a percoater may be used.

Effects The magnetic transfer sheet of the present invention obtained as described above has the following features not found in conventional sheets.

(1) The surface electrical resistance of the magnetic layer is extremely low, and there is no single-frequency charging due to running, so running stability during magnetic transfer is significantly improved.

(2) Related to (11) above, dropouts and noise are reduced because there is no single-frequency charging due to running.

(3) Casen black not only acts as an antistatic agent that lowers the surface electrical resistance, but also acts as a lubricant, improving wear resistance and lowering the coefficient of friction under head load.

6- Examples are shown below.

Magnetic iron oxide (γ-FelO□ Coercive force = 250 Oe) ioOmkfB vinyl chloride resin 15 I acrylic resin
15 l lecithin
1 Kazen Book 2.51 Toluene 150 1 Methyl ethyl ketone 150 A composition was mixed and dispersed in a bowl for 27 hours, and then filtered through a filter with an average pore size of 5 μm. The obtained magnetic paint was applied onto a synthetic paper (trade name: YUPO FPG Φ250J) with a thickness of 25 (1μ), and after drying, a super calender roll coating was applied to form a wide magnetic transfer sheet having a magnetic layer with a thickness of 1Oμ. was obtained and cut into specified dimensions.

Comparative Example A magnetic transfer sheet was prepared in the same manner as in the example using the same set as in the example except for carbon black. A running test was conducted using a magnetic transfer device at 501 RH and the surface electrical resistance and dynamic friction coefficient were measured. The results are shown below. Patent applicant Rico Co., Ltd. −

Claims (1)

[Claims] 1. A magnetic transfer sheet formed by providing a magnetic layer on a non-magnetic support, which contains magnetic powder, a binder, and an antistatic agent containing 2 to 5 particles of Carzen Black with an average particle size of 15 to 40 mμ. .