JPH07243190A - Magnetic recording paper having excellent security - Google Patents

Abstract

PURPOSE:To obtain magnetic recording paper usable for electric measurement such as electrical conductivity and magnetic measurement such as microwave examination without causing trouble in both the measurement, especially no bad influence upon information recording or reading characteristics of magnetic recording paper, having excellent security. CONSTITUTION:(1) This magnetic recording paper is mixed with 0.05-1wt.% based on pulp of fibers whose surface are coated with a metal and has excellent security. (2) This magnetic recording paper uses carbon fibers as fibers. (3) This magnetic recording paper comprises fibers having 3-10mm fiber length and 5-20mum fiber diameter of fibers section, has 1-5mum thickness of a coated metal film, <=1X10<-4>OMEGA.cm electric resistivity of the fibers coated with the metal and excellent security of (1) and (2). The metal fibers have neither problems in paper making nor reduction in physical properties of paper.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to paper used for banknotes, stock certificates, other securities, etc., of which magnetic recording paper is used.

[0002]

2. Description of the Related Art It is necessary to prevent counterfeiting and tampering of cards such as banknotes, stock certificates, other securities and credit cards having a monetary value, and various measures are taken for that purpose. Came. Since the present invention relates to paper such as securities and paper cards, a paper product will be described below. In the case of paper products, methods such as complicated printing such as bills and watermark patterns have been adopted. However, for those who visually or optically judge the authenticity, the place of judgment must be
There is a fundamental drawback of being able to deduce the method. Therefore, in recent years, a method of making a genuine / counterfeit judgment mechanically using electricity or magnetism, and a paper or a card for it have been proposed.

As an example thereof, JP-A-62-219
19, JP-A-5-116243, JP-B 3-1
No. 8232, JP-A-63-501250, JP-A-3-27489 and the like. Describes a paper in which metal fibers are mixed, and by using metal fibers pretreated with a water-soluble binder, it is described that the metal fibers can be well dispersed in the paper despite the difference in specific gravity. There is. As the detection means, "electrical conductivity, magnetism, electromagnetic wave absorption ability, and thermal conductivity" are mentioned. Proposes a composite sheet of a layer containing a conductive fiber and a non-conductive layer, and it is said that it is possible to make a true / false determination based on the conductivity. As the conductive fibers, "metal fibers, carbon fibers, metal-plated fibers, carbon-containing synthetic fibers, copper sulfide-containing polymer fibers" and the like are mentioned.

[0004] In the above, there is a determination of authenticity by microwave,
As a sheet for that purpose, a sheet in which fibers having a conductivity of 10% or less of standard copper are mixed with a non-conductive material is described. Moreover, "Nichrome, titanium, silicon steel, stainless steel" is illustrated as the said fiber.
Relates to a method for checking the authenticity of a document containing particles in the form of electrically conductive fibers, scanning the check area with microwaves and outputting a digital scanning signal characterizing the scanned distribution, which it has on the document. The present invention relates to a method of comparing / checking with a digital mark. Fibers include stainless steel, carbon,
Metal coated polymer fibers are illustrated,
Characters, bar codes, magnetic stripes, etc. are exemplified as the digital mark. Is a method of mixing substances such as conductors that affect radio waves such as microwaves into documents, irradiating radio waves such as microwaves, reading the transmitted or reflected radio waves, digitizing them, and using them as a random number sequence. is there. As the conductor, a metal fiber is exemplified, and as a method of using the random number sequence, in the case of a magnetic card, a method of combining the original magnetic recording information with the random number sequence to encrypt the information is exemplified.

[0005]

[Problems to be Solved by the Invention]

(1) At the time of making paper, the pulp slurry is diluted with a large amount of water and dispersed (for example, a concentration of 0.1 to 0.1).
(1% by weight) to form a paper layer while being dehydrated on a wire, further dehydrated by a press, and dried by a drier. When the metal fiber is mixed with pulp for papermaking, the specific gravity of the metal fiber is too high as compared with water or pulp, so that it precipitates on the wire and is unevenly present on one side of the paper, the curl of the paper, the surface strength of the paper. It causes problems such as deterioration. Also,
There is also a problem that metal fibers cause wear and scratches on wires and rolls of a paper machine.

(2) Carbon fiber has a high conductivity, and a method of mixing the carbon fiber to increase the conductivity of paper is described in the above-mentioned reference, but the conductivity is lower than that of a metal, for example, When the electric resistance is used as the detecting means, there is a disadvantage that a large amount of expensive carbon fiber must be used in order to obtain the electric resistance similar to that in the case of mixing the metal fibers. In addition, since it has a weak ability to absorb microwaves, it cannot be used in a device that uses microwaves as a detecting means.

(3) With respect to the magnetic recording paper,
When adopting the above method, it is necessary to take care so that the conductive fibers mixed in the paper do not adversely affect the original magnetic recording portion. When metal fibers are mixed with paper, if the metal is a ferromagnetic material, the magnetic energy input when recording magnetic information may be absorbed by the magnetic fibers in the paper to give erroneous information. In addition, when the magnetic information is read, there is a risk that erroneous information may be read due to the residual magnetism of the magnetic fiber in the paper. Therefore, there is a problem that it is dangerous to mix the fibers of the ferromagnetic metal with the magnetic recording paper. Ferromagnetic materials are Fe, Co, Ni, G
d, Tb or an alloy compound containing them.

[0008] The present invention is a papermaking problem caused by metal fibers,
It can be used for electrical measurement such as electroconductivity and electromagnetic measurement such as microwave inspection without any problem, and it can be used for information recording or reading characteristics of magnetic recording paper. It is an object of the present invention to propose a magnetic recording paper that does not adversely affect and has excellent security.

[0009]

In order to solve the above problems, the present invention has the following constitution. That is, in the first aspect of the present invention, a fiber whose surface is coated with a metal is added to pulp with a density of 0.
It is a magnetic recording paper excellent in security mixed with 05 to 1% by weight. The second invention is the same as the first invention,
Carbon fiber is used as the fiber, and the third invention is the first or second invention, wherein the fiber has a length of 3 to
10 mm, the diameter of the cross section is 5 to 20 μm, the metal film thickness to be coated is 1 to 5 μm, and the electrical resistivity of the metal-coated fiber is 1 × 10 ⁻⁴ Ω · cm or less. Magnetic recording paper with excellent security.

In the present invention, the magnetic recording paper with excellent security means banknotes, stock certificates, gift certificates, checks and bills, other securities, important documents, prepaid cards, credit cards, boarding passes for various transportation means, A document or card that has a monetary value, such as a passport, passport, or ID card, or has important uses such as guaranteeing your identity.
It is necessary to prove the authenticity, and is made of paper or mainly composed of paper, which has a magnetic recording portion on a part or the entire surface thereof.

The pulp used for producing the paper used in the present invention is not particularly limited as long as it is a pulp used for ordinary printing paper, information recording paper and the like. Chemical pulp (NB
KP, LBKP, etc., mechanical pulp (GP, CGP, R)
GP, TMP, etc.) or deinked waste paper pulp (DIP), or a mixture of these. In addition, synthetic fibers, inorganic fibers and the like may be mixed if necessary.

The magnetic recording paper excellent in security according to the present invention is a single-layer or multi-layered paper made of the above pulp, and has a magnetic recording portion on at least one surface entirely or partially. A synthetic resin layer may be laminated on the surface or between the paper layers, and printing is performed as necessary, or one side or both sides other than magnetic, such as thermal recording, thermal transfer recording, electrostatic recording, etc. It may be an information recording layer.

The fiber used in the present invention is a fiber made of a material other than metal. For example, any of natural fibers such as cellulose, regenerated fibers such as rayon, synthetic fibers such as polyester and polyamide, inorganic fibers such as glass and ceramic, and carbon fibers may be used. The shape of the fibers is preferably in the range of 3 to 10 mm in length and 5 to 20 μm in diameter in order to favorably disperse and retain the fibers during and after papermaking.
When carbon fibers are used, they themselves have high conductivity, and therefore, there is an advantage that the amount of metal in the metal coating can be small when performing electrical detection. The carbon fiber is not particularly limited as long as it is fibrous with a carbon content of 90 mol% or more, and may be manufactured by either the PAN method or the pitch method.

The method of coating the fibers with a metal is not particularly limited, but as a result of coating the fibers, the film thickness of the metal is 1 so that the electric resistivity of the coated fibers is 10 ⁻⁴ Ω · cm or less. A range of up to 5 μm is suitable. The coating method may be any of vapor deposition method, sputtering method, coating method and plating method.

The metal to be coated must have high conductivity, and iron, nickel, chromium, various steel materials, copper,
Various metals such as silver, zinc and aluminum can be used.
Even if a ferromagnetic material such as nickel is used, since the amount of metal field in the entire fiber is small, the magnetic characteristics of the magnetic recording paper are not adversely affected.

In the present invention, the reason why the fiber is coated with a metal is that the metal has the highest response sensitivity when a microwave is used as a means for detecting the authenticity. For example, carbon fiber alone can be similar in conductivity to metal, but
It cannot be detected by microwave.

The magnetic recording paper referred to in the present invention is so-called magnetic recording paper in which a magnetic layer is provided on the paper for magnetic recording, MICR paper in which characters are written with magnetic ink, magnetic stripe, and bar code. It refers to the paper with identification information such as magnetic material attached. The recording layer of the magnetic recording paper is a known magnetic recording layer used for railroad tickets, that is, a recording layer obtained by applying and drying a magnetic paint composed of a ferromagnetic powder and an aqueous binder. Can be used. As the ferromagnetic material, γ ferrite, barium ferrite, strontium ferrite, etc., and as the aqueous binder,
Polyvinyl alcohol, starch, styrene-acrylic copolymer, styrene-butadiene copolymer and the like can be used. Magnetic paints usually have a dry solid content of 20-60 g /
It is applied by a roll coater, an air knife coater, a bar coater, a gravure coater, etc. in a size of about m ² . M
As the ink for ICR, one prepared by kneading a ferromagnetic pigment such as ferrite and a binder such as nitrocellulose or polyamide in a solvent is used.

[0018]

【Example】

<Preparation of magnetic recording paper> For 100 parts of NBKP pulp, nickel-coated carbon fiber (BESFI manufactured by Toho Bethlon
GHT / MC-1) was mixed with the respective amounts shown in Table 1 to prepare a base paper having a basis weight of 150 g / m ² by a hand-papermaking method. In addition, uncoated carbon fiber (BESTIGHT manufactured by Toho Bethlon.
Table 1 shows, as comparative examples, a mixture of 0.5 parts of HTA) and a mixture of 0.5 parts of stainless fibers. For reference, single fiber physical properties of each fiber are shown in Table 2. The undercoat paint below was applied to the above base paper so as to have a dry solid content of 10 g / m ² , dried, and subjected to a super calendar treatment to prepare a base paper. 30g / dry solid content of the following magnetic paint on the base paper
A magnetic recording paper was obtained by applying and drying so as to be m ² . In the examples of the present invention,% represents% by weight and part represents part by weight.

・ Undercoat: 30% light calcium carbonate
Aqueous solution 300 parts, polyvinyl alcohol 12% aqueous solution 5
Liquid with 0 parts mixed and stirred

Magnetic coating: Magnetic powder particles (γ-ferrite having a coercive force of 300 oersted) 70 parts Sodium polycarboxylate 2 parts 12% aqueous casein solution 78 parts Water 60 parts mixed and stirred

<Evaluation> -Papermaking characteristics (a) The sedimentation rate in water of each of the fibers used in the examples was measured alone. For the measurement, 1 liter of water and 0.1 g of fiber were sufficiently stirred in a 1 liter beaker, and then the sedimentation rate (cm / sec) was measured. The results are shown in Table 3. (b) The difference in the abundance between the front surface and the back surface of various fibers of the paper after hand-making was visually observed.・ Microwave inspection machine A microwave is irradiated from the surface opposite to the recording surface of the magnetic recording paper, the reflected microwave is read by the sensor, and the intensity of the reflected wave is continuously plotted in the scanning direction of the paper. Evaluate the authenticity of the paper. The measurement results are shown in FIG. -Magnetic recording characteristics (a) Average playback output voltage Recording and playback were performed with a commercially available reader / writer under the following conditions. Conveyance speed --- 19 cm / sec Recording head --- Permalloy head with a gap of 30 .mu. Reproducing head --- Permalloy head with a gap of 30 .mu. Recording frequency --- 50 FRPI recording current --- 250 mA After recording under the above conditions, reproducing Then, the peak value of each bit of the output is measured, and the average value is used as the average reproduction output voltage. Output is an arbitrary parameter corresponding to voltage,
The value of Example 1 was set to 100. (b) DC noise After the measurement, information was erased with an erasing current of 300 mA, and the maximum value when the output voltage was subsequently measured was taken as the "noise maximum value" and the noise maximum value was divided by the average reproduction output. The% value is regarded as DC noise.

<Outline of Results> As is clear from FIG.
The mixture of metal-coated carbon fibers (Example 1) can be detected by microwaves like the mixture of metal fibers, but the mixture of uncoated carbon fibers is difficult to detect by microwaves. As shown in Table 1, the mixture of metal fibers (Comparative Example 2) tends to have a relatively large DC noise. Further, the papermaking characteristics in Table 1 were obtained as a comprehensive judgment of the sedimentation speed and the visual observation of the front and back surfaces. The steel fibers had a remarkably high sedimentation speed, and there was a difference in the existing amount between the front surface and the back surface.

[0023]

[Table 1]

[0024]

[Table 2]

[0025]

[Table 3]

[0026]

[Figure 1]

[0027]

The following effects can be obtained by the present invention. (1) For security paper mixed with metal fibers,
Although there are problems such as a decrease in the surface strength of the paper, curl properties, and damage to various parts of the paper machine, when the present invention is carried out, such drawbacks are eliminated. (2) With a magnetic recording paper mixed with metal fibers, noise may occur when writing or reading magnetic recording, but in the present invention, there is no such concern. (3) As with the case where metal fibers are mixed, all of the methods for determining authenticity using electrical characteristics or electromagnetic waves can be used.

[0028]

[Brief description of drawings]

FIG. 1 shows a distribution diagram of reflected microwave intensities obtained by scanning a paper. The horizontal axis of the figure is the scanning direction of the paper, and the vertical axis is the intensity of the reflected microwaves.

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[Procedure amendment]

[Submission date] July 21, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Delete

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location D21H 13/50 G11B 5/704

Claims (3)

[Claims] 1. A magnetic recording paper excellent in security in which a fiber whose surface is coated with a metal is mixed in an amount of 0.05 to 1% by weight with respect to pulp. 2. A magnetic recording sheet according to claim 1, wherein carbon fibers are used as the fibers. 3. The length of the fiber is 3 to 10 mm, the diameter of the cross section is 5 to 20 μm, the metal film thickness to be coated is 1 to 5 μm, and the electrical resistivity of the metal-coated fiber is 1 × 10 ^{−. 4} Ω
The magnetic recording paper with excellent security according to claim 1 or 2, wherein the magnetic recording paper is cm or less.