JPH0249355B2 - KINSEKIGAISENKYUSHUZAIOYOBIKENCHIHOHO - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a near-infrared absorber that selectively absorbs specific near-infrared rays and a detection method using the same. More specifically, by selectively absorbing specific near-infrared rays, it is a near-infrared absorbing agent and detector that is effective for verifying and preventing tampering with paper, securities, bankbooks, identification cards, etc., and for taking infrared photographs. Regarding the method.

Conventionally, cash cards, passports, seal certificate cards, various driver's licenses, identification cards, and the like have been provided with various functions for checking and preventing tampering. For example, verification can be done by applying fluorescent material, liquid crystal, conductive material, or magnetic material that is invisible to the naked eye under normal conditions and can only be seen by specific operations. and has a tamper-proof function. These methods, for example, have insufficient anti-visibility effects under normal conditions when viewed with the naked eye, are easily peeled off, damaged or tampered with during use, and cannot be easily verified. However, the verification and tampering prevention functions of conventional methods are not necessarily satisfactory.

Hidden ink using metamerism and printed materials for preventing counterfeiting are also known (Special Publications 1973-
No. 25288, Japanese Unexamined Patent Publication No. 127709/1983). This metamerism is achieved by combining two or more types of pigments that have almost the same color tone in the visible light range, but with different reflectances in the infrared range, under normal conditions with the naked eye. This means that it cannot be seen from below and can only be seen through a filter that transmits only light in the infrared region. However, although metamerism is expected to be a useful tool, there are few pigments that exhibit metamerism, and the emergence of such pigments has been desired.

As a result of intensive studies on verification of various identification cards, prevention of tampering, paper defects, prevention of tampering with securities, etc., the inventors of the present invention have developed a near-infrared absorber and detection method that has better verification and tampering prevention functions than conventional ones. Invented it.

That is, the near-infrared absorber uses at least one phthalocyanine selected from aluminum monochloride phthalocyanine, aluminum monochloride halogenated phthalocyanine, cobalt phthalocyanine, and brominated copper phthalocyanine. Further, a printed matter, a coated product, or a molded product having a near-infrared absorber using at least one phthalocyanine selected from aluminum monochloride phthalocyanine, aluminum monochloride halogenated phthalocyanine, cobalt phthalocyanine, and brominated copper phthalocyanine, This is a detection method that uses near-infrared rays with a dominant wavelength of 750 to 900 nm, and verifies or recognizes them with an infrared absorption detector.

According to the present invention, paints, printing inks, and colored resins are manufactured using a specific phthalocyanine that absorbs near-infrared rays, and are applied to various identification cards, papers, securities, etc., thereby preventing verification and tampering. be able to.

Phthalocyanines that absorb near infrared rays according to the present invention include aluminum monochloride phthalocyanine, aluminum monochloride halogenated phthalocyanine, cobalt phthalocyanine, and brominated copper phthalocyanine, and these phthalocyanines
Absorption of near-infrared rays above 700 nm, especially from 750 to 900 nm, is stronger than that of copper phthalocyanine, which is commonly used as a pigment.

Near-infrared rays refer to electromagnetic waves with wavelengths in the range of 700 to 2,500 nm, but in the present invention, it is preferable to use near-infrared rays having a main wavelength in the range of 750 to 900 nm. It is also desirable to use laser beams with uniform wavelengths. In the detection method of the present invention, an infrared absorption detector is usually used, but near-infrared radiation by other devices may also be used.

The near-infrared absorber of the present invention is usually used in a dispersed state in a resin, for example, in a printing ink, paint, or resin composition (film, sheet, etc.), but it can also be used in a vapor-deposited state.

Near-infrared absorbers can be used in products such as identification cards, paper products, and filters, and can also be used in conjunction with printing inks and paints that use copper phthalocyanine, which is commonly used as a pigment, to prevent counterfeiting with a metamerism effect. It is also possible to obtain printed matter and molded products with this ability.

According to the present invention, the above-mentioned phthalocyanine is dispersed in a resin used for printing ink, paint, etc. in an attritor, sand mill, or ball mill to form a printing ink or paint, and then printed or applied to the target object. reach your goal. Printed matter obtained in this way can only be recognized as a simple blue printed matter when visually inspected with the naked eye under normal conditions, but it can be recognized by using conventionally known infrared detection devices and filters. , it is possible to recognize that it is a specific printed matter, etc.

Therefore, by applying the near-infrared absorbent of the present invention to identification cards, paper defects, etc., recognition and verification can be easily performed using a simple detection means, and falsification, etc., can be prevented.

In addition, printed matter, coated products, and molded products to which the near-infrared absorbing agent of the present invention is applied can be photographed using infrared photography used for aerial photography, photogrammetry, appraisal photography, spectrophotography, and photography for special effects. If you take a picture with the object on, it will help you recognize it and prevent damage.

Note that it can also be used as a near-infrared absorbing filter by uniformly dispersing it in a resin or the like and making it into a film. This will be explained in detail below using examples.

Example 1 An offset ink was prepared by kneading a mixture of 9 g of aluminum chloride phthalocyanine and 1 g of α-type copper phthalocyanine with 50 g of linseed oil using a triple roll (this was referred to as ink A). This ink was printed on art paper using an offset printing proofing machine and dried (this printed material is referred to as printed material A).

For comparison, a printed matter was produced using an ink (hereinafter referred to as ink B) prepared in the same manner from 10 g of β-type copper phthalocyanine and 50 g of linseed oil (this printed matter shall be referred to as printed matter B).

Although the difference in hue between Print A and Print B could not be discerned with the naked eye, when an infrared absorption detector was used, absorption was detected in Print A, but no absorption was detected in Print B.

Ink A and Ink B were placed in a quartz cell and the absorption spectra were measured using a spectrophotometer (UV-365 manufactured by Shimadzu Corporation), and the results are shown in FIGS. 1 and 2. As is clear from the figure, 750~
Absorption is observed at 900 nm, especially from 800 to 850 nm, but in FIG. 2, almost no absorption is observed in the same wavelength range. For this reason, it is possible to print securities etc. using the pigment shown in this example at a wavelength of 800.
By using an infrared absorption detector that can detect light of ~850 nm, it can be easily identified and is effective in preventing tampering.

Example 2 1 Aluminum chloride nucleus Chlorinated phthalocyanine (1 chlorine substitution number of phthalocyanine nucleus) 10g, alkyd resin 20g, melamine resin 5g, xylene 40g
g, ethyl acetate 5g, isobutyl alcohol 10
g and 10 g of methyl ethyl ketone were placed in a ball mill and kneaded for 48 hours. The paint thus obtained was applied to an iron plate and baked at 180°C for 30 minutes to create a coated plate (this will be referred to as coated plate A). For comparison, a coated plate was prepared using β-type copper phthalocyanine instead of aluminum monochloride-nucleated chlorinated phthalocyanine (this was referred to as coated plate B). When these two coated plates were photographed in a dark room using an infrared camera for night photography, coated plate B could be photographed, but coated plate A could not be photographed at all.

Example 3 In Example 2, cobalt phthalocyanine or brominated copper phthalocyanine (the number of bromines substituted for phthalocyanine is 4) was used in place of the aluminum monochloride-nucleated chlorinated phthalocyanine, and tests were performed on each coated plate in the same manner, and almost the same results were obtained. I got it.

[Brief explanation of drawings]

FIGS. 1 and 2 are graphs of absorption spectra measured using a spectrophotometer, in which the horizontal axis shows wavelength and the vertical axis shows absorbance.

Claims (1)

[Scope of Claims] 1. A near-infrared absorber characterized by using at least one phthalocyanine selected from monoaluminum phthalocyanine chloride, aluminum chloride halogenated phthalocyanine, cobalt phthalocyanine, and brominated copper phthalocyanine. 2. The near-infrared absorber according to claim 1, which is obtained by dispersing the phthalocyanine in a resin. 3 Printed matter, coated matter, or molded matter having a near-infrared absorber made of at least one phthalocyanine selected from monoaluminum phthalocyanine, aluminum chloride halogenated phthalocyanine, cobalt phthalocyanine, and brominated copper phthalocyanine, at a wavelength of 750 A detection method characterized by using near-infrared rays having a main wavelength of ~900 nm and performing verification or recognition with an infrared absorption detector. 4. The detection method according to claim 3, which uses a near-infrared absorber made by dispersing the phthalocyanine in a resin. 5. The detection method according to claim 3 or 4, which is a printed product, coated product, or molded product using the above phthalocyanine and a phthalocyanine other than the phthalocyanine.