JP2008045231A - Multi-layered sheet and method for determining true or false - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multi-layered sheet produced by forming invisible images on a nonwoven fabric with a plurality of different transparent materials and then using the sheet as a middle layer to make the sheet, and to provide a method for determining whether the multi-layered sheet is genuine or not on the basis of transmission imaging by infrared spectroscopy. <P>SOLUTION: This multi-layered sheet produced by applying invisible information to at least one side of a nonwoven fabric with at least two or more kinds of different transparent materials, nipping the invisible information-applied nonwoven fabric between an upper layer paper material and a lower layer paper material on a paper-making machine to form a multi-layered sheet having the upper layer paper material layer, the nonwoven fabric layer and the lower paper material layer, and then drying the formed multi-layered sheet in the drying section of the paper-making machine. And, the method for determining whether the multi-layered sheet is genuine or not includes determining the multi-layered sheet on the basis of transmission imaging by infrared spectroscopy. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a multilayer sheet obtained by forming an invisible image using a plurality of different transparent materials on a non-woven fabric, and making the sheet as an intermediate layer, and a method of determining authenticity of the multilayer sheet based on transmission imaging in infrared spectroscopy It is.

  For printed matter that requires security, such as banknotes, securities, and passports, an authenticity determination element for distinguishing genuine products from counterfeit products is indispensable in order to suppress forgery. For this reason, a large number of printed materials in which a plurality of authenticity determination elements are provided in a complex configuration by various methods have been proposed, and as one of means for determining the authenticity of these printed materials, Many methods for determining authenticity using a simple device have been proposed.

  As an example, a pattern printing layer is provided with normal ink on at least one side of a sheet of paper, and the surface of the pattern printing layer is printed using fluorescent inks such as hidden patterns and hidden letters using multiple fluorescent inks. Provide a layer. At that time, as the fluorescent inks, forgery-proof printed matter that is printed with ink that is colorless in the visible light region such as white light such as sunlight and fluorescent lamps, and changes in color with different hues by ultraviolet irradiation is proposed. Has been. This is because hidden pictures and letters printed using multiple fluorescent inks cannot be seen under sunlight, etc., but they are raised by irradiating ultraviolet rays with an ultraviolet lamp, and authenticity determination is performed. (For example, refer to Patent Document 1).

  In addition, a printed matter has been proposed in which characters and designs are formed on the inner surface of the sheet when the sheet is formed in multiple layers. In this method, fluorescent coloring particles that are colored by ultraviolet rays are included in the entire lower layer web or the surface, and the upper layer web is laminated with a part of the paper layer being thinned. When ultraviolet light is irradiated from the upper layer side of the obtained paper, the creased portion where the paper layer is thin emits fluorescence, and the authenticity is determined by raising the embeded pattern (see, for example, Patent Document 2).

  In addition, a sheet is inserted into the middle layer on the endless paper web of the paper machine and sandwiched between multiple raw material layers to form a multilayer wet web on the endless paper web. Forming letters or designs by blending or printing using one or more of specific substances with specific or magnetic properties, or making fine holes in the middle sheet, and depending on the size and arrangement of the holes, letters and designs A multi-layered laminated paper in which is formed has been proposed (for example, see Patent Document 3).

  In addition, image formations in which image information such as letters and numbers is given in advance using a specific element from sodium to uranium, and the image information is covered using an arbitrary method on the image information have been proposed. . This is done by using a fluorescent X-ray analyzer to perform mapping based on the fluorescent X-ray spectrum of a specific element and recognizing authenticity by recognizing image information such as letters and numbers hidden in the concealed portion as an image. (For example, refer to Patent Document 4).

Utility Model No. 25595770 JP 2001-81698 A JP 2003-13395 A JP 2000-218920 A

  However, when printing is performed on the surface of the sheet as proposed in Utility Model No. 25595770, even if the ink used is colorless and transparent, a difference occurs between the gloss value of the sheet and the gloss value of the ink. There is a problem of lack of concealment power as a pattern.

  In addition, when characters and designs are formed by the method proposed in Japanese Patent Laid-Open No. 2001-81698, the characters and designs printed on the inner surface of the sheet depend on the clearance, and fine characters and designs are formed. There is a problem that it is difficult.

  In addition, special ink and rare ink must be used in the method of authenticating with reflected light by irradiating specific light, and when multiple printing with those inks is performed, the material printed above There is a problem that it is difficult to acquire the image of the image printed below.

  In addition, analysis using various elemental analysis methods (fluorescent X-ray, SEM-EDX, FTIR-ATR) has a problem that it takes time for mapping and often requires pretreatment and the like.

  The present invention aims to solve the above-described problems. Specifically, a multi-layer sheet in which an invisible image is formed using a plurality of different transparent materials on a sheet and the sheet is made as an intermediate layer, and the sheet The present invention provides a method for determining authenticity of multilayer sheets using transmission imaging in infrared spectroscopy.

  The multilayer sheet of the present invention is a multilayer sheet comprising an upper paper layer, an intermediate paper layer having at least a non-woven fabric layer coated with two or more different transparent materials, and a lower paper layer.

  The multilayer sheet of the present invention is a multilayer sheet in which two or more different transparent materials are partially different in chemical composition, and information is applied to the nonwoven fabric with the transparent material.

  The multilayer sheet authenticity determination method of the present invention is such that at least one surface of a nonwoven fabric is subjected to invisible information by at least two kinds of different transparent materials, and the nonwoven fabric subjected to the invisible information is treated with an upper layer stock and a lower layer on a paper machine. A method for determining the authenticity of a multi-layer sheet by forming a multi-layer sheet having an upper layer paper layer, a non-woven fabric layer, and a lower layer material layer by heating and drying in a drying section of a paper machine. , Select the resolution and image pixel size in infrared spectroscopy in advance, determine the conditions, acquire the average absorbance image by transmission imaging for the multilayer sheet under the selected conditions, By dividing the area into different transparent materials, acquire infrared spectra at arbitrary points for each area. 2) Select the peak wave number derived from the functional group for each of the two different transparent materials, perform chemical imaging for each of the selected peak wave numbers, and apply the information provided by at least two different transparent materials obtained by chemical imaging. The authenticity determination method of a multilayer sheet is characterized in that authenticity determination is performed by comparing the chemical imaging image of the above and an authentic chemical imaging image acquired in advance.

  The method for analyzing a multilayer sheet according to the present invention is characterized in that the region is divided for each different transparent material, and therefore, the region is divided and stored in advance at the stage of producing the multilayer sheet.

  There is no need to use special inks or rare inks, and since an invisible image is formed on the intermediate layer of the sheet, the information hiding power is increased.

  Due to the analysis by transmitted light, even when a plurality of invisible images are formed in multiple layers, it is possible to acquire individual images without being affected by the material formed above.

  It is possible to acquire several types of invisible image images formed at once by measurement of an infrared spectrum.

  Since differentiation by functional groups can be achieved, even if formed using optically similar transparent or same color materials, differentiation is possible due to the difference in structure.

  Non-destructive and invisible image can be acquired, and no complicated preprocessing is required.

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a multilayer sheet in the present invention. FIG. 2 shows an apparatus for producing a multilayer sheet according to the present invention. FIG. 3 shows the principle of obtaining an infrared spectrum in the FTIR imaging method. FIG. 4 shows the authenticity determination method of the multilayer sheet in the present invention. FIG. 5 shows a reflection image of a multilayer sheet in one embodiment of the present invention. FIG. 6 shows an average absorbance image in one example of the present invention. FIG. 7 shows an infrared spectrum in one embodiment of the present invention. FIG. 8 shows a single wave number image of 1705 cm ⁻¹ in one embodiment of the present invention.

  FIG. 1 shows a multilayer sheet in the present invention. The multilayer sheet (5) has an upper paper layer (1) made of fibers, an intermediate layer made of nonwoven fabric (2), and a lower paper layer (3) made of fibers. An invisible image (4) is printed on the intermediate layer (2) using a plurality of different transparent materials. The printing method is not particularly limited.

  The non-woven fabric referred to in the present invention means that various fiber webs are processed mechanically, chemically, thermally or a combination thereof without using a loom, and the constituent fibers are bonded to each other by the adhesive or the fusing force of the fibers themselves. It refers to the cloth you made.

  The transparent material can be printed on the nonwoven fabric of the intermediate layer and is difficult to visually recognize after being combined with the upper and lower layers, and can be latex, colorless fluorescent material, infrared, etc. There are no particular limitations on materials having absorption or infrared reflection characteristics, microcapsules, and the like.

By using latex, emulsion, solution, suspension (suspension) or the like having heat-fusible properties as the transparent material, it is possible to improve the interlayer bonding strength of the multilayer sheet and to produce a multilayer sheet having an excellent anti-peeling effect. When a heat-fusible material is used, the softening point is preferably about room temperature to 100 ° C. The room temperature here means a temperature at which the binder to be used does not melt, and is about 30 ° C.

  By using the non-woven fabric (2) for the intermediate layer of the multilayer sheet (5), the lower paper layer (3), the non-woven fabric (2), and the upper paper layer (1) are bound to each other with the fibers intertwined during papermaking. Therefore, the delamination prevention effect is excellent. The fiber (5) constituting the nonwoven fabric may be further improved in delamination preventing effect by using fibers such as polyvinyl alcohol (PVA), ethylene vinyl alcohol (EVA), rayon, PET, etc., but is particularly limited. Whatever is used, not what is used.

  The thickness of the nonwoven fabric is about 10 μm to 200 μm, preferably about 10 μm to 60 μm. The width | variety of a nonwoven fabric (2) is not specifically limited, You may provide in strip shape between an upper paper layer (1) and a lower paper layer (3). When providing in strip shape, it is also possible to provide a plurality.

  The fibers used for the upper paper layer (1) and the lower paper layer (3) are not particularly limited, and chemical pulps such as KP and SP made from plant fibers such as wood and cotton, GP and TMP In addition, mechanical pulp such as CTMP or pulp such as used paper recycled pulp can be appropriately selected and used.

  The multilayer sheet of the present invention can be subjected to other anti-counterfeiting techniques, such as colored fibers or strips, colorless fluorescent fibers or strips, colored fluorescent fibers or strips, magnetic fibers or strips, metal strips. , Aluminum strips, fibers or strips having infrared absorption characteristics, fibers or strips having infrared reflection characteristics, thermochromic fibers or strips, and the like can be mixed, and threads It is also possible to apply a cut-in image or the like. However, it is desirable that the material to be mixed is a material that does not hinder when acquiring an invisible image of the intermediate layer.

  Next, a multilayer sheet manufacturing apparatus will be described with reference to FIG.

  FIG. 2 shows an overall configuration of a long paper machine (8) which is a multilayer sheet manufacturing apparatus. The long net paper machine (8) comprises a net band and has a circulating wire (9) for endless papermaking. The wire (9) is bridged between the driven pulley (10) and the driving pulley (11), and is guided while being supported by a plurality of rolls (not shown) arranged inside along the wire (9). Has been circulating.

  From the upstream side to the downstream side of the upstream portion of the wire (9), the lower layer stock supply tank (12), the nonwoven fabric supply device (13), the upper layer stock supply tank ( 14) are sequentially arranged at intervals.

  The lower layer stock supply tank (12) and the upper layer stock supply tank (14) are respectively filled with the lower layer stock (15) and the upper layer stock (16), and are appropriately replenished from a supply source (not shown). The liquid level is controlled to be maintained. The lower layer stock (15) and the upper layer stock (16) are materials that are materials of the lower paper layer (3) and the upper paper layer (1), and are mainly composed of pulp fibers, water, and additives.

  In each downstream portion of the lower layer material supply tank (12) and the upper layer material supply tank (14), a lower sheet material sealing plate (17) and an upper layer material sealing plate (18) are respectively arranged. ing. The lower layer stock and the upper layer stock are supplied onto the wire (9) through the gap between the lower layer stock plate (17) and the upper layer stock plate (18) and the wire (9), respectively. Paper making is possible.

  The nonwoven fabric supply part of the nonwoven fabric supply apparatus (13) is provided on the downstream side of the lower layer stock supply tank (12) and the upstream side of the upper layer stock supply tank (14), and is formed on the wire (9). The non-woven fabric (2) is supplied onto the lower base stock layer (wet paper) (19). The nonwoven fabric supply device (13) includes a nonwoven fabric supply drum (20) and a tension roll (21).

  The width (w) of the strip-shaped nonwoven fabric (2) supplied from the nonwoven fabric supply device (13) is formed by being supplied from the lower layer material sealing plate (17) to the upper surface (conveying surface) of the wire (9). The upper layer is substantially the same as the width of the lower layer paper layer (lower wet paper) (19), and is further supplied to the upper surface of the lower layer material layer (19) from the upper sheet material sealing plate (18). The width of the stock layer (upper wet paper) (22) is substantially the same.

  The nonwoven fabric supply drum (20) moves along the longitudinal direction of its axis (direction perpendicular to the paper surface in FIG. 2), that is, in the width direction of the nonwoven fabric (2), and moves along with the wound nonwoven fabric, and is positioned in the width direction. The non-woven fabric supply drum width direction position adjusting device (not shown) is adjusted so as to be adjusted.

  A water squeezing box (23) is disposed below the wire (9) at the downstream side (the movement terminal portion on the upper surface of the wire). This water extraction box (23) sucks water contained in the lower layer paper layer (19), the nonwoven fabric (2) and the upper layer material layer (22) in the downstream portion of the wire (9) in the paper making process. And squeezing water.

  The multilayer sheet (5) formed of the wire (9) is guided by a guide roll (not shown) and wound up as a final product by a winding roll, but between the wire (9) and the winding roll from the upstream side. A press roll (24) and a drying device (25) are provided. The press roll (24) is used in the case where the multilayer sheet is scraped.

  The press roll (24) sandwiches the multilayer sheet (5) and further feeds it to the downstream winding roll side. The gap is formed by the well-known press roll (24) or tundee roll (26). The drying device (25) uses a known drying device.

  Next, the manufacturing method of a multilayer sheet is demonstrated with reference to FIG.2 and FIG.4.

  An invisible image is printed on the nonwoven fabric using two or more kinds of transparent materials having different chemical compositions (STEP 1). A printing system will not be specifically limited if it is a system which can be printed on a nonwoven fabric, such as flexographic printing, offset printing, or inkjet printing.

  Using a long net paper machine (8), the printed non-woven fabric is bonded together in the paper layer. The lower layer material (15) is supplied from the lower layer material supply tank (12) to the upper surface of the circulating wire (9) through the gap between the lower sheet material sealing plate (17) and the wire (9) (STEP2 ). The lower layer stock (19) supplied on the wire (9) is sent in the paper making direction as the lower layer stock layer (19).

  A strip-shaped nonwoven fabric (2) is continuously supplied from the nonwoven fabric supply device (13) to the upper surface of the lower layer stock layer (19) (STEP 3). The strip-shaped non-woven fabric (2) and the lower layer stock layer (19) are overlapped while being sent in the paper making direction on the wire (9), and the lower layer stock (15) enters between the fibers of the non-woven fabric (2). The pulp fibers of (15) and the fibers of the nonwoven fabric (2) are entangled to produce a strong bond between them.

  On the upper surface of the strip-shaped nonwoven fabric (2) overlapped with the pulp fibers of the lower layer stock (15), the gap between the upper layer stock supply tank (14) and the upper layer stock sealing plate (18) and the wire (9) The upper layer stock (16) is supplied through (STEP 4). The upper layer stock (16) overlaps the non-woven fabric (2) while being sent in the paper making direction as the upper layer stock layer (22) on the wire (9), and the upper layer stock (16) is between the fibers of the non-woven fabric (2). Get in. Thus, by producing a multi-layer sheet with a long paper machine, the pulp fiber of the upper layer stock (16) is intertwined with the fibers of the non-woven fabric (2), and the lower layer paper that has already entered the non-woven fabric (2). Also entangled with the pulp fiber of the material (15), a strong bond is formed.

  The multilayer sheet (5) bonded to the multilayer passes through the squeezing box (23) and squeezes water (STEP 5). At this time, the fibers of the lower layer stock (15), the non-woven fabric (2), and the upper layer stock (16) are intertwined and intertwined to form a strong bonding layer.

  The multilayer sheet from which water has been squeezed passes through the drying device (25) and is dried (STEP 6). When the heat-fusible material is printed on the non-woven fabric, the bonding strength between the non-woven fabric layer and the paper layer is further increased by the partial melting of the heat-fusible material at the time of drying, and the peeling prevention effect is improved.

  The multilayer sheet (5) heated and dried by the drying device (25) is wound up by the reel device (27) to be completed as a final product (STEP 7).

  Moreover, when giving a penetration to a multilayer sheet | seat (5), it passes through a squeezing box (23) and gives a penetration with a press roll (24).

  It is also possible to produce multilayer sheets having different colors, basis weights, or fiber configurations by changing the stock properties of the raw materials stored in the lower layer stock supply tank (12) or the upper layer stock supply tank (14). . The color can be adjusted by the difference in the type of fiber, pigment and dye mixing and bleached or unbleached, etc. The basis weight can be adjusted by adjusting the raw material concentration and the raw material discharge part. The adjustment can be made by changing the fiber type, blending ratio, fiber length, beating degree, and the like.

  The multilayer sheet (5) can be formed in a form in which one side of the nonwoven fabric is exposed, but in order to enhance the concealing effect of invisible information imparted to the nonwoven fabric, it is preferable that there is no exposed portion. However, an image with different opacity is formed by using two or more kinds of materials having different optical characteristics as a material for forming an invisible image, and an image that is viewed with different reflected light image and transmitted light image at the exposed portion. Can be formed. In addition, since the tactile sensation is different in the exposed portion of the nonwoven fabric, it is also possible to provide an exposed portion when providing such anti-counterfeit effect together.

The exposed portion forming device (28) for forming the exposed portion includes a liquid discharge nozzle, an air discharge nozzle, a press roll, a dandy roll, and the like. The liquid discharge nozzle and the air discharge nozzle are controlled so as to be ejected at regular intervals in accordance with the paper making speed, and exposed portions are formed at regular intervals. Similarly, the rotational speed of the press roll or dandy roll is controlled together with the papermaking speed, and exposed portions are formed at regular intervals. You may give the exposed part which at least one part of an image exposes by injecting compressed air to a lower layer paper layer (19) and / or an upper layer paper layer (22) with at least one air nozzle. The compressed air of the air nozzle can control the position, timing, air pressure, and the like according to the paper making speed, and the direction of jetting is perpendicular to the lower stock layer (19) and / or the upper stock layer (22). Direction is preferred. Further, it is also possible to form an exposed portion by ejecting liquid using a liquid ejection nozzle instead of the air nozzle. The pressure is about 0.5 to 4.0 Kg / cm ² , and the direction of jetting is preferably perpendicular to the lower stock layer (19) and / or the upper stock layer (22).

  The authenticity determination method of a multilayer sheet is demonstrated with reference to FIG.3 and FIG.4.

  The multilayer sheet having an invisible image printed on the intermediate layer is analyzed by the FTIR transmission method to obtain an infrared spectrum. In this imaging method, an invisible image is obtained by determining the peak wave number derived from the functional group of each material constituting the invisible image from this infrared spectrum and performing mapping.

  First, the multilayer sheet is analyzed by transmission imaging to obtain an average absorbance image (STEP 8). As shown in FIG. 3, the principle is that the sample (6) to be analyzed is irradiated with infrared rays (29) and measured by the detector (30) in units of pixels, and an average absorbance image is obtained based on the measured pixels. How to get. The method of measuring with the detector (30) includes a method of detecting one pixel (31) at a time, a method of measuring a spectrum of a wide range of pixels at once, and imaging measurement by linking the measurement of a plurality of pixels and the movement of the stage. The method of performing is mentioned.

  As selection conditions before measurement, resolution and image pixel size are selected. The imaging pixel size is selected from either 6.25 μm × 6.25 μm or 25 μm × 25 μm. An imaging pixel size of 6.25 μm × 6.25 μm is selected when imaging a minute part with high sensitivity, and an imaging pixel size of 25 μm × 25 μm is selected when imaging a wide area at high speed. However, since the imaging size varies depending on the device to be used, it is not limited to this, and it is desirable to select an imaging pixel size suitable for the device to be used.

The resolution is preferably 8 cm ⁻¹ for a base material such as paper that is difficult to transmit light, and 4 cm ⁻¹ for a base material that is nearly transparent and easily transmits light. It is desirable to select the optimal resolution according to the application, the measurable time, etc.

  Secondly, the acquired average absorbance image is divided into regions for different transparent materials, and infrared spectra at arbitrary points in each divided region are acquired (STEP 9).

  Third, from the acquired infrared spectrum, the peak wave number derived from the functional group of each printed transparent material is selected, and chemical imaging is performed for each peak wave number to obtain each imaging image (STEP 10). At this time, as the peak wave number for performing chemical imaging, a wave number that does not overlap with peaks derived from components contained in the material contained in the multilayer sheet and other printed materials is selected. If the wave numbers overlap, an accurate imaging image may not be acquired.

  About a multilayer sheet (5), the form in which the single side | surface of a nonwoven fabric is exposed may be sufficient, and the conditions selection and procedure of an analysis method do not change. When other anti-counterfeiting effects due to the difference in optical characteristics and tactile sensation of the exposed portion are also provided, it is possible to provide the exposed portion.

  Whether the multilayer sheet is genuine or not is determined by comparing the obtained chemical imaging image of the multilayer sheet with a previously acquired chemical imaging image of the genuine multilayer sheet.

  In addition, the infrared spectrum of each material (fiber, filler, additive, etc.) included in the multilayer sheet and the material to be printed may be measured in advance, and the acquired infrared spectrum may be compared with the spectrum measured in advance. Is possible.

  Explains the production procedure and authenticity determination method for the examples of the present invention using data (sheet type, type of transparent material used, and peak wavelength value derived from functional group) when actually producing a multilayer sheet. To do.

The nonwoven fabric used as the intermediate layer was made of polyvinyl alcohol having a basis weight of 12 g / m ² and a thickness of 35 μm.

  Two types of latex of modified styrene / butadiene copolymer were used as transparent materials. As the latex to be used, latex (A) and latex (B) having a composition and properties different from those of latex (A) were used.

  The composition of the latex (A) is styrene · 40 ppm, 1,3-butadiene · less than 10 ppm, acrylic acid · less than 0.03%, methyl methacrylate · less than 0.04%. The latex has a solid content concentration of 50%, a pH of 8.5, a particle diameter of 320 nm, and a glass transition temperature of 85 ° C.

  The composition of the latex (B) is styrene 50 ppm, 1,3-butadiene 10 ppm, acrylamide 30 ppm, methyl methacrylate 30 ppm. The latex has a solid content concentration of 50%, a pH of 5.7, a particle diameter of 320 nm, and a glass transition temperature of 100 ° C.

Using a coater device, two types of latex were partially shifted and applied to the non-woven fabric. It was applied at a coating speed of 10 m / min by a gravure method and dried at a hot air drying temperature of 100 ° C. After drying with hot air, it was wound around a paper tube to prepare a nonwoven fabric coated with a binder. The coating amount was 10 g / m ^{2 in} total, each 5 g / m ^{2 of} latex.

  Next, the multilayer sheet was made using the multilayer sheet manufacturing apparatus shown in FIG. The lower layer material (19) discharged from the lower layer material supply tank (16) passes through the gap between the lower sheet material sealing plate (21) and the wire (12), and is circulated on the upper surface of the wire (12) being circulated. Supply. The lower layer stock (23) supplied on the wire (12) is sent in the paper making direction as a lower layer stock layer (lower wet paper) (23).

  The binder-coated nonwoven fabric (2) produced by the above method is set on the nonwoven fabric supply drum (24), and the binder-coated nonwoven fabric (2) is applied to the upper surface of the lower layer stock layer (23) from the nonwoven fabric feeder (17). ) Is continuously supplied. The upper layer stock (20) discharged from the upper layer stock supply tank (18) is further sealed on the upper surface of the strip-shaped nonwoven fabric (2) overlapped with the pulp fibers of the lower layer stock (19). It is fed through the gap between the plate (22) and the wire (12).

  The multilayer sheet (5) bonded to the multilayer passes through the squeezing box (23), and further passes through the drying drum device (32) at 50 ° C to 120 ° C to complete the multilayer sheet.

  FIG. 5 shows a reflection image of a multilayer sheet in which two types of latex are applied at different positions, and a position where each latex is applied.

Analysis by transmission imaging under conditions of a resolution of 16 cm ⁻¹ and an imaging pixel size of 25 μm × 25 μm is shown in FIG.

FIG. 7 shows an infrared spectrum of an arbitrary point (+1 to +4) in the average absorbance image acquired in FIG. In the infrared spectrum acquired from position +1 and +3, (high absorbance) strong near 1,705Cm ^-1 peak is confirmed, the infrared spectrum obtained from the point of + 4, weak in the vicinity of 1705 cm ^-1 (absorbance (Low) peak was confirmed. Further, from the measurement of the infrared spectrum of only each of the latex, the latex (A) is (high absorbance) strong near 1,705Cm ^-1 indicates a peak, the latex (B), weak near 1,705Cm ^-1 It has been confirmed that it shows only a peak (low absorbance), and the infrared spectrum acquired from the locations of +1 and +3 is derived from latex (A), and the infrared spectrum acquired from the location of +4 is latex (B) It can be said that it comes from.

FIG. 8 is a diagram obtained by performing single wave number imaging at a peak near 1,705 cm ⁻¹ derived from components in the latex from the infrared spectrum acquired in FIG. 7.

  The single wave number image shown in FIG. 8 can be said to be a distribution image of each latex applied to the nonwoven fabric forming the middle layer of the multilayer sheet. Furthermore, since separation was possible depending on the type of latex, an invisible image of two different types of latex formed on the inner surface of the multilayer sheet could be visualized with an IR image.

The multilayer sheet in this invention is shown. The manufacturing apparatus of the multilayer sheet in this invention is shown. The principle of obtaining an infrared spectrum in the FTIR imaging method will be described. The analysis procedure of the multilayer sheet in this invention is shown. The reflection image of the multilayer sheet | seat in one Example of this invention is shown. The average-absorbance image in one Example of this invention is shown. The infrared spectrum in one Example of this invention is shown. The single wave number image of 1,705cm < ^-1 > in one Example of this invention is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Upper paper layer 2 Nonwoven fabric 3 Lower paper layer 4 Image by transparent material 5 Multi-layer sheet 6 Sample to be analyzed 7 Hot air drying device 8 Long paper machine 9 Paper making wire 10 Drive pulley 11 Drive pulley 12 Lower paper supply tank 13 Non-woven fabric supply device 14 Upper layer stock supply tank 15 Lower layer stock 16 Upper layer stock 17 Seal plate for lower layer stock 18 Seal plate for upper layer stock 19 Lower layer stock layer (lower wet paper)
20 Nonwoven fabric supply drum 21 Tension roll 22 Upper layer stock layer (upper wet paper)
23 Water-squeezing box 24 Press roll 25 Heating / drying device 26 Tundy roll 27 Reel device 28 Exposed portion forming device 29 Infrared 30 Detector 31 1 pixel

Claims (3)

A multilayer sheet comprising an upper paper layer, an intermediate paper layer having at least a non-woven fabric layer coated with two or more different transparent materials, and a lower paper layer. The multilayer sheet according to claim 1, wherein the two or more different transparent materials have partially different chemical compositions, and information is applied to the nonwoven fabric by the transparent material. A method for determining authenticity of a multilayer sheet according to claim 1 or 2,
The resolution and the image pixel size in infrared spectroscopy are selected in advance and conditions are determined. Under the selected conditions, an average absorbance image is obtained by transmission imaging for the multilayer sheet, and the obtained average absorbance image is obtained. On the other hand, each of the different transparent materials is divided into regions, an infrared spectrum of an arbitrary point is acquired for each of the regions, and functional groups for the at least two different types of transparent materials are acquired from the acquired infrared spectra. Select the peak wave number of the origin, perform chemical imaging for each selected peak wave number, and obtain in advance the chemical imaging image of the information applied by the at least two different transparent materials obtained by the chemical imaging Compared with genuine chemical imaging image Authenticity discrimination method for a multilayer sheet which is characterized in that the authenticity discrimination by.

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