JP2012021235A - Paper provided with cellulose microfilament - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide paper enabling discrimination of its authenticity by machine-reading with regard to the paper used in valuable printed matters such as paper money, passports, securities, stamps, certificates or entry tickets.SOLUTION: Paper of this invention has an area for authenticity discrimination at least in a part of base material, and the area for truth discrimination has a dispersion fluid including cellulose microfilament applied thereto. Provided is the paper having cellulose microfilament enabling authenticity discrimination by machine-reading by difference in a light transmission quantity, difference in air permeability, difference in light emission wavelength, difference in chemical structure or difference in color density by coloring; although the difference between an application part provided with the cellulose microfilament dispersion fluid and a non-application part not provided with the cellulose microfilament dispersion fluid is invisible from visual observation under the reflection and the transmission of visible light.

Description

  The present invention relates to paper used for valuable printed matter such as banknotes, passports, securities, stamps, certificates or admission tickets, and particularly relates to paper that can be determined by machine reading.

  Valuable printed materials such as banknotes, passports, securities, cards, stamps, certificates or admission tickets are required to have a function to prevent counterfeiting and unauthorized copying. This prevention measure is roughly classified into a technique for providing a forgery prevention function in a sheet and a technique for providing a forgery prevention function in printing. Examples of the technology for imparting the anti-counterfeit function in the paper include squeeze, mixed paper, or multilayer paper. Examples of the technology for imparting the anti-counterfeit function in printing include a fine image line structure, an intaglio image line, or a fluorescent light emission. Is mentioned.

  However, in recent years, high-performance scanners, personal computers, printers, and the like have become widespread, and there is a tendency for a third party to easily produce counterfeit products. Furthermore, counterfeit products made with high-performance scanners, personal computers, printers, etc. are becoming difficult to differentiate from genuine products by visual judgment alone. For this discrimination, machine reading technology is an effective means.

  As a specific method of determining authenticity using machine reading technology, IR absorption ink is used and detection is performed using an infrared light sensor, and fluorescence ink is used to detect light emission when irradiated with ultraviolet light. The method is widely used. Furthermore, in actually adopting these methods, as a measure for preventing forgery or the like, the given information is concealed in some form.

  Further, if printing is classified from the viewpoints of information source, output scale, and user's relationship with printed materials, it can be divided into large-scale commercial printing and personal printing. Large-scale commercial printing has been promoted for the purpose of making large-scale and high-speed copies of paper and other information sources. On the other hand, there are inkjet and laser methods for personal printing, and the main usage is to output documents created on a personal computer or information obtained from the Internet on paper as personal records. Over the last few years, on-demand printing methods have been adopted that take advantage of the ability to provide variable information with high definition. Therefore, there is a demand for a paper that can be applied to on-demand printing and has a forgery preventing effect and a true / false discrimination effect.

  On the other hand, in recent years, technological progress has been remarkable, and it has become possible to apply not only synthetic materials but also natural materials such as cellulose when creating nanoscale products. As an example, a cellulose-based raw material is oxidized, and the oxidized cellulose is subjected to wet atomization to produce nanofibers (hereinafter referred to as “cellulose nanofibers”), and a papermaking additive comprising the cellulose nanofibers is added. In addition, there is disclosed a printing paper that improves the air resistance and smoothness of paper by coating or impregnating the paper, and is excellent in ink inking property and prevention of back-through (for example, see Patent Document 1). .

  Further, by providing one or more coating layers on the paper coated with a paper additive made of cellulose nanofibers on the surface, coated paper for offset printing with improved white paper gloss and printing gloss, and A coated paper for gravure printing with few missing dots is disclosed (for example, see Patent Documents 2 and 3).

JP 2009-263850 A JP 2009-263853 JP 2009-263854 A

  However, in the case of IR-absorbing inks and fluorescent inks that are used as a means of machine reading technology, as these technologies become widespread and generalized, related technical information is made public and resistant to counterfeiting. Has been declining, and damages due to counterfeiting and alteration are continuing.

  In addition, when these inks, transparent pigments, etc. are applied to the paper, the gloss and color are different between the applied part and the non-applied part, so that the applied part can be visually recognized and some processing is performed on a part of the paper. There was a problem that it was understood at a glance that

  Furthermore, IR-absorbing ink, fluorescent ink, and the like are poor in recyclability and environmental harmony, and there are materials with high costs. Therefore, they may not be used depending on product cost restrictions.

  As for the techniques described in Patent Document 1, Patent Document 2 and Patent Document 3, all of the papers are coated with cellulose nanofibers (or double-coated), and the paper smoothness, ink fillability or It is a technique for the purpose of improving the glossiness and the like, and is not a sheet processed for the purpose of authenticity determination intended by the present invention.

  The present invention is intended to solve the above-described problems, and relates to a paper in which a dispersion liquid in which cellulose microfibers are dispersed is applied to a part of a substrate.

  The paper provided with cellulose microfibers according to the present invention has a region for authenticity determination on at least a part of the base material, and the region for authenticity determination is provided with a cellulose microfiber dispersion liquid in which cellulose microfibers are dispersed. The difference between the imparted part to which the cellulose microfiber dispersion is applied in the authenticity discrimination region and the non-applied part to which the cellulose microfiber dispersion is not applied is under reflected light and transmitted light by visible light. It is characterized by being invisible visually.

  The paper provided with the cellulose microfiber in the present invention is characterized in that the fiber width in the cellulose microfiber is 2 nm or more and less than 10 μm.

The paper provided with cellulose microfibers according to the present invention is characterized in that the solid content after drying of the cellulose microfibers applied to at least a part of the substrate is 0.01 to 30 g / m ² .

  The paper provided with cellulose microfibers according to the present invention is characterized in that it is used as authenticity discrimination paper by machine reading.

  According to the present invention, the mechanical reading of the paper to which the cellulose microfibers are applied is the difference in the amount of transmitted light, the difference in the air permeability, the difference in the emission wavelength, the difference in the chemical structure, or the difference in the color density due to the coloring in the imparted part and the non-given part. It is the reading by.

  By using the material constituting the paper of the base material and the same shape of fiber and cellulose material of the same material, gloss, whiteness, color or texture, etc., in the imparted part and non-applied part of cellulose microfiber It was not visible visually under visible light. For this reason, it is not known at a glance that the paper has undergone some processing, and it is not easily forged.

  Under visible light, the applied part cannot be visually confirmed, but authenticity can be determined by machine reading based on differences in the amount of transmitted light, air permeability, emission wavelength, chemical structure, etc. Became.

  Unless the paper is subjected to any treatment, the visible portion cannot be visually observed under visible light.However, by printing or coloring the paper, the imparted portion and the non-given portion of the cellulose microfibers are changed in color and the imparted portion is changed. It is visible under visible light, and authenticity can be determined by a simple method.

  Further, since the paper itself has an element for authenticity determination, it can be applied as a paper for on-demand printing such as a resident card.

  Since natural fibers such as cellulose are used, recyclability and environmental harmony are improved. Moreover, reduction of product cost can be expected.

The top view of the paper which provided the cellulose microfiber in this invention is shown. The top view of the paper which provided the cellulose microfiber in Example 1 is shown. The authenticity determination result of the paper in Example 1 is shown. The top view of the paper which provided the cellulose microfiber in Example 2 is shown. 9 shows the authenticity determination result of the paper in Example 2. The top view of the paper which provided the cellulose microfiber in Example 3 is shown.

  DESCRIPTION OF EMBODIMENTS Embodiments for carrying out the present invention will be described with reference to the drawings. However, the present invention is not limited to the embodiments described below, and includes various other embodiments within the scope of the technical idea described in the scope of claims.

  FIG. 1 is a plan view of a sheet according to the present invention. The paper (1) in the present invention has an authenticity determination area (3) in at least a part of the substrate (2), and cellulose fine fibers are dispersed in the authenticity determination area (3). A dispersion liquid (hereinafter referred to as “cellulose fine fiber dispersion liquid”) is applied. Hereinafter, the part to which the cellulose fine fiber dispersion is applied is referred to as “applied part”, and the part to which the cellulose fine fiber dispersion is not applied is referred to as “non-applied part”.

  Further, the shape of the imparting portion in the authenticity determination area (3) possessed by at least a part of the base material (2) may be a symbol shape having meaningful information as shown in FIG. As shown in FIG. 1B, the substrate may be strip-shaped.

  The base material (2) in the present invention is a sheet formed of a material having water absorption, such as paper made of wood or non-wood pulp, synthetic fiber paper made of synthetic fiber, nonwoven fabric or film, There is no particular limitation. However, the base material formed from fibrous materials, such as paper, synthetic fiber paper, or a nonwoven fabric, is more preferable. In the case of a film or the like, when a large amount of cellulose fine fiber dispersion is applied, the applied portion may be visible under visible light.

  In addition, in FIG. 1A and FIG. 1B, the application portion is illustrated in a state where it is colored and can be visually recognized. Cannot be visually recognized under reflected or transmitted light by visible light.

  Cellulose microfibers in the present invention are fibers mainly composed of cellulose, particularly those using plant-derived natural cellulose as a raw material, and those fibrillated into fine cellulose fibers having a fiber width of less than 2 nm to 10 μm. Say.

  The term “defibration” as used herein refers to unraveling cellulosic fibers up to several micro or nanofibrils. Usually, the cellulose fiber obtained from a plant is an aggregate of cellulose nanofibrils composed of 30 to 50 cellulose molecules and having a fiber width of about 2 to 5 nm. Cellulose microfibrils are firmly bonded by innumerable hydrogen bonds, but can be broken into several units of cellulose micro or nanofibrils while remaining in a fibrous state by applying physical or chemical treatment.

  As a method of defibration, a physical method includes a method of microfibrillation by a mechanical shearing force by a high-pressure homogenizer or a method of atomization by adding an organic solvent to mechanical grinding by a dry ball mill. Further, as a method by chemical treatment, there are a method of removing a non-crystalline portion of cellulose fibers by a sulfuric acid treatment, a method of introducing a carboxyl group only on the surface of crystalline cellulose microfibrils by an oxidation treatment, and the like. These methods are all known methods, and the defibration performed for producing the paper in the present invention is also performed by a known method.

  When the fiber width of the cellulose fiber is 10 μm or more, it becomes the same order as 10 to 30 μm, which is the fiber width of a general pulp fiber, and characteristics specific to microfibers cannot be obtained. Therefore, the term “microfiber” as used herein refers to a fiber having a cellulose nanofibril unit of about 2 nm to less than 10 μm, particularly preferably 2 nm to less than 1 μm, and more preferably 2 nm to less than 100 nm.

  Cellulose microfibers are mainly composed of fibers composed of cellulose, but the fibers composed of cellulose are not particularly limited. Chemical pulps such as KP or SP made from various wood materials, GP, TMP, or CTMP Pulp such as mechanical pulp, recycled paper recycled pulp and the like can be appropriately selected and used, and powdered cellulose obtained by pulverizing them, microcrystalline cellulose purified by chemical treatment, and the like can also be used. Further, non-wood such as kenaf, hemp, rice, bagasse, abaca, cotton, mitsumata or bamboo can also be used.

  Cellulose microfibers are dispersed in water to prepare a cellulose microfiber dispersion. It is possible to add a dispersant, a water-soluble polymer, a water-soluble liquid that does not inhibit the dispersion state of cellulose microfibers, or a powder or fine particles.

  In addition, the cellulose fine fiber dispersion needs to have a concentration such that the fibrillated microfibers are not immediately recombined by hydrogen bonding, and is preferably used at a solid content concentration of about 1 to 3%. However, if the microfibers can be re-separated by vigorous stirring of the dispersion or addition of a dispersing agent, there is no problem even if it is about 3 to 35%.

  This is because, when the solid content concentration is 35% or higher, re-defining treatment may be necessary because recombination of the microfibers cannot be suppressed only by adding stirring or a dispersing agent. On the contrary, when the solid content concentration is 1% or less, there is a possibility of promoting the swelling of the paper due to excessive moisture in the application and drying stages. However, there is no particular limitation as long as these problems can be avoided by other means.

  The method of applying the cellulose fine fiber dispersion to at least a part of the substrate (2) is a screen printing, flexographic printing, gravure printing, ink jet printing, or the like, or a size press coater, gate roll coater, blade coater. Alternatively, coating may be performed by a coating machine such as a bar coater or impregnation.

The amount of the cellulose microfiber dispersion applied varies depending on the method of application, but it is necessary to prepare so that the solid content of the cellulose microfiber after drying is about 0.01 to 10 g / m ² . However, if the application portion of the cellulose fine fiber dispersion is not visible under visible light, there is no problem even if applying about 10 to 30 g / m ² .

This is because when the solid content exceeds 30 g / m ² , the application part of the cellulose fine fiber dispersion is visible under reflected light and transmitted light by visible light, and the possibility of forgery increases. On the other hand, when the solid content is 0.01 g / m ² or less, the machine reading accuracy, which is the effect of applying the fine fibers, is lowered, and it is difficult to obtain an accurate result.

  Depending on the application method, the application limit amount at one time may be equal to or less than the amount, but in this case, application may be repeated several times to obtain a target solid content.

  As for the length of the cellulose microfiber, since the fiber length of wood pulp is usually about 0.5 to 3 mm, the minimum limit length is less than this, but the maximum limit length varies depending on the application method. For example, in the screen printing method, it is necessary to be less than the length that can pass through the screen mesh, in the flexographic printing method, it is necessary to be less than the length that can be transferred to the cell of the roll, and in the inkjet printing method, it is necessary to be less than the length that can be ejected from the ejection port.

  As described above, after the cellulose fine fiber dispersion is applied to at least a part of the substrate, the substrate is dried to produce the paper in the present invention.

  In the paper thus prepared, the portion to which the cellulose fine fiber dispersion is applied cannot be visually recognized under reflected light or transmitted light by visible light. However, since the characteristics of the paper change between the portion to which the cellulose fine fiber dispersion liquid is applied and the other portions, it is possible to determine authenticity by machine reading.

  Examples of the machine reading include those based on the amount of transmitted light, those based on the air permeability, those based on the emission wavelength, those based on the chemical structure, and those based on the color density change due to coloring.

  First, machine reading based on transmitted light amount will be described.

  This is a method in which the applying unit performs machine reading from the difference in transmitted light amount because the density of the fibers is higher than the non-applied portion and the transmitted light amount is different.

  As an apparatus to be used, for example, a scanner, an infrared scanner, a spectrophotometer, or the like is used. This is not particularly limited as long as the device can measure the amount of light transmitted through the paper.

  As a method, first, the transmitted light amount value of the applying portion and the transmitted light amount value of the non-applied portion are measured. Next, the measured transmitted light amount values are compared and calculated, and the difference between the transmitted light amount value of the applying portion and the transmitted light amount value of the non-applied portion is calculated. Next, it is compared whether or not the difference in the calculated transmitted light amount value is within an allowable range of the transmitted light amount value stored in advance. As a result of the comparison, a genuine product is determined if it is within the allowable range, and a counterfeit product is determined if it is outside the allowable range.

  As another method, first, a transmission image of the assigning unit is acquired. The acquired transmission image and an image stored in advance are compared and collated by pattern matching or the like. If they match, a genuine product is determined, and if they do not match, a forged product is determined.

  Next, machine reading based on air permeability will be described.

  This is a method of performing machine reading from the difference in air permeability since the imparting part has a higher fiber density and different air permeability than the non-giving part.

  As an apparatus to be used, for example, an air permeability meter or the like is used. This is not particularly limited as long as the device can measure the air permeability of the paper.

  As a method, first, the air permeability value of the imparting part and the air permeability value of the non-given part are measured. Next, the measured air permeability values are compared, and the difference between the air permeability value of the imparting part and the air permeability value of the non-given part is calculated. Next, it is compared whether or not the difference in the calculated air permeability value is within an allowable range of the air permeability values stored in advance. As a result of the comparison, a genuine product is determined if it is within the allowable range, and a counterfeit product is determined if it is outside the allowable range.

  Next, machine reading based on the emission wavelength will be described.

  This is a method of performing machine reading by measuring one of the characteristics of cellulose fibers, fluorescence emission characteristics. The fiber derived from cellulose has a characteristic of emitting fluorescence having an intensity of 500 to 600 nm when irradiated with a laser beam of 450 to 500 nm, and uses this.

  As an apparatus to be used, for example, a laser microscope or a confocal laser microscope is used. This is not particularly limited as long as it is a device capable of confirming fluorescence emission by irradiating a laser beam.

  As a method, first, a laser beam with a wavelength of 450 to 500 nm is irradiated onto the applying portion. Next, the emission intensity with respect to irradiation is measured. If the fluorescent light is emitted at 500 to 600 nm with respect to the irradiation, the genuine product is judged.

  As another method, first, a laser beam of 450 to 500 nm is irradiated on the applying unit, and then an image of fluorescence emission with respect to irradiation is acquired. The acquired fluorescence image and the image stored in advance are compared and collated by pattern matching or the like, and if they match, a genuine product is determined, and if they do not match, a forged product is determined.

  However, when machine reading is performed based on fluorescence emission characteristics, the substrate is preferably a sheet made of fibers not derived from cellulose, such as synthetic fiber paper. If the base material is a fiber derived from cellulose, it emits fluorescence even when the non-applied part is irradiated with a laser beam of 450 to 500 nm, and is it emitted by the part to which the cellulose microfiber dispersion is applied? This is because it may not be possible to distinguish whether light is emitted by the cellulose-derived fiber of the base material itself.

  However, even in the case of a substrate made of cellulose-derived fibers, it is possible to determine authenticity by machine reading from a difference in emission intensity depending on conditions. For example, when cellulose microfibers are applied to the surface of the base paper, the fluorescence emission intensity from a substance close to the surface layer is detected higher. In addition, since the cellulose microfiber has a larger surface area than the cellulose-derived fiber in the base paper, the fluorescence emission intensity may be high. In such a case, a threshold value of the fluorescence emission intensity is determined, and a portion showing an intensity higher than the threshold value is an imparting portion, and a portion showing a low intensity is a non-giving portion, and machine reading based on the difference in emission intensity can be performed.

  Moreover, a fluorescent pigment etc. can be mixed beforehand in a cellulose fine fiber dispersion liquid, and they can also be read.

  Next, machine reading by chemical structure will be described.

  This is a method of performing machine reading based on the difference in chemical structure of the fiber surface when cellulose microfibers are prepared by a chemical treatment method. It shows a different chemical structure from the surface of the fibers constituting the base paper, such as many carboxyl groups remaining on the surface of the cellulose microfibers. It is a method of using it.

  As an apparatus to be used, for example, an X-ray photoelectron analyzer (ESCA), an infrared spectroscopic analyzer (IR), an infrared spectroscopic total reflection measurement apparatus (IR-ATR), or the like is used. This is not particularly limited as long as it is an analytical instrument that can analyze the chemical structure of the fiber surface.

  As a method, first, the chemical structure of the imparting part is acquired by an analytical instrument. The chemical structure of the cellulose microfiber is measured in advance, and if the chemical structure of the imparting part matches the chemical structure of the cellulose microfiber, the genuine product is judged, and if it does not match, the counterfeit product is judged.

  As another method, in the case of an apparatus that can acquire a mapping image due to a difference in chemical structure, the mapping image is acquired. The mapping image of the granted portion obtained and the mapping image of the non-given portion are compared and collated by pattern matching or the like. If they match, the genuine product is determined, and if they do not match, the forged product is determined.

  After preparing the cellulose microfibers, it is possible to intentionally introduce substituents or metal components and analyze them. Moreover, synthetic fiber paper can also be used for a base material.

  Next, machine reading by color density change due to coloring will be described.

  This is a method of performing machine reading by coloring the whole surface of a paper provided with cellulose microfibers or a part including an application part with a coloring material and causing a difference in color density between the application part and the non-application part. .

  As a device to be used, for example, a print densitometer, a color densitometer, or the like is used. This is not particularly limited as long as it can measure the color density.

  As a method, first, the density value of the imparting part and the density value of the non-given part are measured. Next, the measured density values are compared and calculated, and the difference between the density value of the imparting part and the density value of the non-given part is calculated. Next, it is compared whether the calculated density value difference is within an allowable range of density values stored in advance. As a result of the comparison, a genuine product is determined if it is within the allowable range, and a counterfeit product is determined if it is outside the allowable range.

  The principle of the difference in color density due to coloring between the part to which the cellulose microfibers are applied and the part to which the cellulose microfibers are not applied is that the part to which the cellulose microfibers are applied has high fiber density and few voids. On the other hand, the coloring material accumulates on the surface of the microfibers, and the portions not provided with the coloring material penetrate into the base material. Therefore, the portion to which the cellulose microfibers are imparted is visually recognized as a dark color having a high color density on the printing surface side, and the portion to which the cellulose microfibers are not imparted is visually recognized as a light color having a low color density on the printing surface side.

  The coloring material may be any liquid that can be colored, such as a colored ink, a colored pigment dispersion, or a colored dye solution. Preferably, a difference in color density is more likely to occur in a pigment dispersion having a particle diameter larger than the fiber width of cellulose microfibers or an aqueous liquid penetrating into paper. In addition, a colorless fluorescent material or the like can be used even if it is colorless under visible light as long as it is a material that can be authenticated by reading the fluorescent color density.

  In addition, as a coloring method, printing or printing is performed by various printing methods such as inkjet printing, flexographic printing, gravure printing, or offset printing, or the coloring material is spilled or written or drawn using a coloring material. That's fine. Any method may be used as long as it can be colored on the entire surface or a part of the paper provided with cellulose microfibers.

  In addition, as described above, as an example of machine reading, an example based on a change in color density due to coloring was given. However, in this regard, it is possible to determine authenticity by visual observation, and only the imparting part is raised (the color density is high). If it is in a state, it can be judged as a genuine product, and if nothing comes out, it can be judged as a counterfeit product.

  A first embodiment of the present invention will be described with reference to FIG. Fig.2 (a) shows the top view of the paper (1-1) which provided the cellulose microfiber in this invention.

  The paper (1-1) according to the present invention has an authenticity determination area (3-1) in at least a part of the base material (2-1), and the authenticity determination area (3-1) is included in the authenticity determination area (3-1). Is provided with a cellulose fine fiber dispersion. In Example 1, at least a part of the base material (2-1) is a heavy circular region shown in the lower left of the drawing.

  Cellulose microfibers used “Selish 100G (trade name)” manufactured by Daicel Chemical Industries, Ltd. This was stirred and diluted to prepare a cellulose fine fiber dispersion having a solid content of 2% and used for printing. Cellulose microfibers were applied by screen printing using an 80-line mesh (opening 247 μm, plate thickness 119 μm).

  FIG. 2B shows an example in which a gift certificate is made using the paper (1-1) shown in FIG. The gift certificate is produced by giving other information to the paper (1-1) produced by the method described above. As other information, the face value and the design of the gift certificate were used, and the design was printed by offset printing.

  In the gift certificate produced in this way, authenticity determination is performed by coloring. A magenta ink dedicated to the printer was printed on the authenticity determination area (3-1) provided with cellulose microfibers using an inkjet printer (PM-890C manufactured by EPSON).

  As shown in FIG. 3A, in the uncolored paper (1-1), nothing is visible in the authenticity determination area (3-1), but as shown in FIG. In the later paper (1-1), the color density appeared dark only in the part where the cellulose microfibers were added to the authenticity determination area (3-1). As a result, the gift certificate was determined to be genuine.

  A second embodiment of the present invention will be described with reference to FIG. Fig.4 (a) shows the top view of the paper (1-2) which provided the cellulose microfiber in this invention.

  The sheet (1-2) according to the present invention has an authenticity determination area (3-2) in at least a part of the base material (2-2), and the authenticity determination area (3-2) Is provided with a cellulose fine fiber dispersion. In Example 2, at least a part of the base material (2-2) is a region having a jagged contour illustrated in the lower left of the drawing.

  Cellulose microfibers used “Selish 100G (trade name)” manufactured by Daicel Chemical Industries, Ltd. This was stirred and diluted to prepare a cellulose fine fiber dispersion having a solid content of 2% and used for printing. Cellulose microfibers were applied by screen printing using an 80-line mesh (opening 247 μm, plate thickness 119 μm).

  FIG. 4B shows an example of a gift certificate using the synthetic fiber paper shown in FIG. The gift certificate is produced by giving other information to the paper (1-2) produced by the method described above. As other information, the face value and the design of the gift certificate were used, and the design was printed by flexographic printing.

  Machine reading of the gift certificate produced in this way is performed. First, using a confocal laser microscope, a portion of the paper (1-2) including the authenticity determination area (3-2) was irradiated with an argon laser of 458 nm.

  As a result, fluorescence derived from cellulose having a fluorescence emission wavelength in the range of 500 to 600 nm was detected, and it was determined that the gift certificate was genuine.

  FIG. 5 shows a fluorescence emission image of a part of the portion to which cellulose microfibers are applied. A white part (X) shown in the image is a fluorescent light emitting part, and shows a part to which cellulose microfibers are given. Depending on the case, it is possible to compare and collate the acquired fluorescence emission image with a prestored image by pattern matching or the like, and to determine whether the image is a genuine product or a counterfeit product if they do not match.

  A third embodiment of the present invention will be described with reference to FIG. Fig.6 (a) shows the top view of the paper (1-3) which provided the cellulose microfiber in this invention.

  The sheet (1-3) according to the present invention has an authenticity determination area (3-3) in at least a part of the base material (2-3), and the authenticity determination area (3-3). Is provided with a cellulose fine fiber dispersion. In Example 3, at least a part of the substrate (2-3) was a band-like region illustrated below the drawing.

Cellulose microfibers used “Selish 100G (trade name)” manufactured by Daicel Chemical Industries, Ltd. This was stirred and diluted to prepare a cellulose fine fiber dispersion having a solid content of 2%, which was used for application. Application was performed in a strip shape using a bar coater so that the solid content of the cellulose microfiber after drying was 3 g / m ² .

  FIG. 6B shows an example of a gift certificate using the paper (1-3) shown in FIG. The gift certificate is produced by giving other information to the paper (1-3) produced by the method described above. As other information, the face value and the design of the gift certificate were used, and the design was printed by offset printing.

  Machine reading of the gift certificate produced in this way is performed. Using an optical scanner (EPSON scanner 2200), the transmission image of the entire gift certificate was read at a setting of positive film, 16-bit gray, and 400 dpi. The gray level tone output level was corrected, and a transmission image (not shown) of the cellulose microfiber application part was obtained.

  The acquired transmission image and the image stored in advance were compared and collated by pattern matching or the like, and a genuine product was determined if they matched, and a counterfeit product was determined if they did not match. As a result, it was determined that the gift certificate is a genuine product by determining that it matches.

1, 1-1, 1-2, 1-3 paper 2, 2-1, 2-2, 2-3 base material 3, 3-1, 3-2, 3-3 authenticity determination area

Claims (5)

At least part of the base material has an area for authenticity determination,
The authenticity determination area is formed by adding cellulose microfibers,
The difference between the imparted portion to which the cellulose microfibers are imparted in the authenticity determination region and the non-given portion to which the cellulose microfibers are not imparted cannot be visually recognized under reflected light or transmitted light by visible light. A sheet provided with cellulose microfibers. The paper provided with the cellulose microfiber according to claim 1, wherein a fiber width of the cellulose microfiber is 2 nm or more and less than 10 μm. 3. The cellulose microfiber according to claim 1, wherein a solid content after drying of the cellulose microfiber to be applied to at least a part of the substrate is 0.01 to 30 g / m ^2. Paper. Use of a sheet provided with the cellulose microfiber according to any one of claims 1 to 3 as a genuineness determination sheet by machine reading. The mechanical reading is a reading based on a difference in transmitted light amount, a difference in air permeability, a difference in light emission wavelength, a difference in chemical structure, or a difference in color density due to coloring in the application unit and the non-application unit. Use according to claim 4.

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