JPH0788435B2 - Plastic film and method of using the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a plastic film used for various electromagnetically identifiable prepaid, credit, cash cards, securities, and the like.

[Prior Art] Conventionally, a card punch, an embossed character, or a record or a secret code stored in a magnetic stripe has been used as a means for confirming the authenticity of various cards such as prepaid, credit, and cash. . In addition, even in securities, forgery prevention methods such as watermarking have been taken [Problems to be solved by the invention] However, card punches and embossed characters are provided with an identification function by simply processing the card. In addition, even in the magnetic stripe, the recorded contents are relatively easy to read and write, so that the confidentiality is poor and it is easy to forge.

In addition, watermarks in securities cannot completely prevent counterfeiting, and in reality, various troubles are caused by counterfeit products. The problem of the security of such cards and securities has been emphasized with the increase of artificial use of cards and the increase of the amount of money, and it is inevitable that it becomes more important in the future.

The purpose of the present invention is to provide an anti-counterfeiting function to the film itself used for the original sheet (base) of cards and securities, and to prevent the counterfeiting of cards and securities by using this original film, thereby ensuring confidentiality and security. There is a place to improve.

[Means for Solving the Problems] (1) The magnetic particles having an average particle diameter of 0.05 to 10 μm are 0.001
A plastic film containing up to 10% by weight, wherein the contained magnetic particles are magnetized and the surface of the plastic film itself has non-uniform electromagnetic characteristics, (2) Average grain 0.001 for magnetic particles with a diameter of 0.05-10 μm
A method for using a plastic film, which comprises applying a magnetic field to a plastic film containing 10 to 10% by weight and then reading the magnetization state using a magnetic reproducing device.

As the plastic film in the present invention, polyester, polyphenylene sulfide, polyolefin,
Films mainly composed of thermoplastic polymers such as polyamide, polyurethane and vinyl polymers can be mentioned, but polyester films are preferable from the viewpoints of surface characteristics, physical characteristics and the like. The polyester referred to herein means polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycyclohexylene dimethylene terephthalate, polyethylene bisphenoxycarboxylate, or modified products thereof. Among these, a polyester film containing polyethylene terephthalate as a main component is particularly preferably used in terms of dimensional stability, strength, transparency and the like.

The plastic film of the present invention has magnetic particles dispersed in the film, and a magnetic sensor detects a magnetic signal output,
For example, when used as a card, each card can be identified from the difference in the distribution state of the signal output of the card. Therefore, when the content of the magnetic particles exceeds 10% by weight, the difference in the distribution of the output becomes small and the identification function deteriorates.

Further, if the content is less than 0.001% by weight, there are some portions where the output signal is not detected. The preferable content of the magnetic substance is 0.01 to 7% by weight, more preferably 0.5 to 5% by weight.

The average particle size of the magnetic particles used in the present invention is 0.05 to
The thickness is 10 μm, preferably 0.1 to 5 μm. When the particle size of the magnetic material is less than 0.05 μm, it becomes difficult to detect a magnetic signal, and when it is more than 10 μm, the flatness of the surface of the film deteriorates and the appearance becomes poor.

In the present invention, the non-uniformity of the electromagnetic characteristics of the surface means that the magnetic signal of the film obtained by magnetizing the magnetic substance in the film to a substantially saturated state with a DC magnetic field has a reading part by a fixed head for audio and an oscillograph. When the film was run at a running speed of 24 mm / sec using a magnetic regenerator and observed for 50 msec at a rate of 1 point at 200 μsec, the signal output was 50-100% of the maximum signal output in the read section. It means that% part and 0-50% part are mixed. The preferable non-uniformity is that the portion where the output is 0 to 50% of the maximum signal output of the reading unit is 3 to 9 of the observation time.
9.5%, more preferably 20 to 90%.

The magnetic particles applied to the present invention are not particularly limited, barium ferrite, strontium ferrite,
Calcium ferrite, zinc ferrite, lead ferrite, magnesium ferrite, γ ferrite, α ferrite, cobalt γ ferrite, nickel zinc ferrite, manganese zinc ferrite, magnetite, chromium dioxide, nickel oxide, oxide magnetic components such as cobalt oxide and iron, nickel, A metal magnetic component composed of a simple substance such as chromium or an alloy, or a mixed magnetic component thereof is preferably used. In particular, in order to detect a low-density non-uniform signal, it is preferable that the residual magnetization (residual magnetic flux density) in the magnetization curve of the magnetic particles is large. A magnetic metal component consisting of a simple substance or an alloy is preferable.

The film of the present invention may be a layer containing magnetic particles only, but may be a laminated film in which one or more layers containing no magnetic particles are laminated, if desired. In the case of a laminated film, the layer containing the magnetic material may be a surface layer or an intermediate layer. As long as a magnetic signal can be detected, it is also preferable to use a layer containing a magnetic material as an intermediate layer and use a layer having other characteristics such as printability and adhesiveness as the surface layer.

In addition, titanium oxide, calcium carbonate, calcium silicate, calcium sulfate is added to both the layer containing a magnetic material and the layer not containing a magnetic material for the purpose of imparting properties such as slipping property and light-shielding property as desired. , Barium sulfate, calcium phosphate, aluminum oxide, magnesium oxide,
Inorganic particles such as silica, kaolin, talc, mica and zeolite can be added.

[Examples] Examples will be shown below for further detailed description.

Example 1 Granules of polyethylene terephthalate having an intrinsic viscosity of 0.65 98
Parts by weight and 2 parts by weight of γ-ferrite having an average particle size of 0.2 μm were melt-mixed using an extruder. The resulting mixture is 18
After drying at 0 ° C. for 2 hours, it was subjected to a normal melt biaxial stretching film forming machine and stretched 3.3 times in the machine direction and 3.3 times in the transverse direction. thickness
A biaxially stretched film of 200 μm was obtained. The film containing the obtained magnetic particles was magnetized in a direct current magnetic field until it was almost saturated, and then the film was cut into a card shape having a length of 5 cm and a width of 10 cm.

Using a magnetic playback device that has a reading section with an audio fixed head and an oscillograph, the above card is
Run at a speed of / sec and at a rate of 1 point every 200 μsec
The signal output was observed for 50 msec. The portion of the signal output that is 0 to 50% of the maximum output of the observed signal is the observation time.
It was 54%.

In addition, when the magnetic signal output was detected in the same way for other cards cut from the same film, the maximum signal output was
The 0 to 50% portion was 51% of the observation time. But 2
The distribution of the signal output of the cards was quite different.

Example 2 Polyethylene terephthalate granules having an intrinsic viscosity of 0.65 99.5
Parts by weight and strontium ferrite with an average particle size of 1.2 μm
0.5 parts by weight of the mixture was melt-mixed with an extruder to obtain a mixture A as a granular material.

95 parts by weight of polyethylene terephthalate particles having an intrinsic viscosity of 0.65 and 5 parts by weight of titanium oxide having an average particle diameter of 0.3 μm were melt-mixed using an extruder to obtain a mixture B of particles.

2 equipped with two extrusion bases and a die capable of two-layer melt coextrusion
Using an axially stretched film forming machine, the mixture A was supplied to one extruder and the mixture B to the other extruder, and stretched 3.3 times in the longitudinal direction and 3.3 times in the transverse direction to form a layer containing titanium oxide of 150 μm. A biaxially stretched film in which two layers containing a magnetic material having a thickness of 30 μm were laminated was obtained.

A direct current magnetic field was applied to the obtained film to magnetize it almost to saturation, and then cut into a card shape having a length of 5 cm and a width of 10 cm. Using the same apparatus as in Example 1, the magnetic signal output on the layer side containing the magnetic material of the card was observed under the same conditions, and as a result, the output was 0 to 50% with respect to the maximum output of the observed magnetic signal. The part was 73% of the observation time. Other cards cut from the same film were similarly observed. As a result, 0 to 50% of the maximum output of the observed signal was 76% of the observation time. Also, the distributions of the signal outputs of the two cards were different.

Claims (2)

[Claims] 1. Magnetic particles having an average particle diameter of 0.05 to 10 μm
A plastic film containing 001 to 10% by weight, wherein the contained magnetic particles are magnetized and the surface of the plastic film itself has non-uniform electromagnetic characteristics. 2. A magnetic material particle having an average particle diameter of 0.05 to 10 μm.
A method of using a plastic film, which comprises applying a magnetic field to a plastic film containing 001 to 10% by weight and then reading the magnetized state using a magnetic reproducing device.