JP5447781B2 - Color variable ink composition - Google Patents

Description

The present invention includes gift vouchers such as gift certificates, securities, stock certificates, various cards such as credit cards, prepaid cards, ID cards, tickets, banknotes, passports, identification cards, public competition voting tickets, video software, PC software, etc. The present invention relates to a color variable ink composition having an excellent anti-counterfeit effect and constituting various anti-counterfeit bodies such as authenticity determination seals used in (hereinafter referred to as security objects).
In general, electromagnetic waves can be classified as ultraviolet rays, visible rays, and infrared rays. In the present invention, the visible light region, that is, the visible region is 360 nm to 830 nm (JIS Z8120), and light having a shorter wavelength than the visible light is used. Ultraviolet light, and that region is the ultraviolet region. Further, light having a wavelength longer than that of visible light is infrared, and the region is an infrared region.
In general, the visible region is “purple”: 380 nm to 450 nm, “blue”: 450 nm to 495 nm, “green”: 495 nm to 570 nm, “yellow”: 570 nm to 590 nm, “orange”: 590 nm to 620 nm, “red”: 620 nm Although it is divided into ˜750 nm, the change is continuous, and this classification is an example.
In addition, the ultraviolet region in the present invention refers to a region whose range is determined from the characteristics of the pigment of the present invention, and refers to one region in a general near ultraviolet region: 380 nm to 200 nm. Furthermore, the infrared region in the present invention refers to a region whose range is determined based on the characteristics of the pigment of the present invention, but refers to one region in a general near infrared region: 830 nm to 2500 nm.
In the present invention, the “incident angle of light to be observed”, that is, the direction perpendicular to the plane of the color variable ink layer (hereinafter referred to as color variable ink layer) formed using the color variable ink composition is the reference direction. When the color variable ink layer surface is observed with the “angle to the reference direction” being “0 to 70 degrees to observe”, the “wavelength of selectively reflected light” (in accordance with the incident angle) ( Meaning that the light exiting in the regular reflection direction is only a part of the selected wavelength component of the incident light wavelength component)), that is, a pearl pigment, an effect pigment, The present invention relates to a color variable ink composition containing a liquid crystal pigment and the like.

Pearl pigments are natural mica flakes (also called mica flakes) coated with a transparent metal oxide. Effect pigments are natural alumina flakes, artificially synthesized alumina flakes, silicon oxide flakes (silica). Flakes), borosilicate glass flakes and the like are coated with a transparent metal oxide.
Usually, when the color variable ink layer is observed and visually determined, it is performed at an angle of 0 to 70 degrees with respect to the reference direction. Observation at 80 to 90 degrees is not performed unless otherwise specified.
As the liquid crystal pigment, a three-dimensional cross-linking substance having a liquid crystal structure having a chiral phase can be used. In particular, a cholesteric liquid crystal pigment having wavelength-selective reflected light is suitable.
Cholesteric liquid crystals are induced by adding a small amount of optically active substances (chiral agents) to nematic liquid crystals, and have a constant refractive index change in the liquid crystal layer by having a helical structure with a constant period with respect to the reference direction. Layers are stacked. The multilayer structure having this refractive index distribution has the property of reflecting incident light for observation at a predetermined angle after selecting the wavelength. The wavelength of the selectively reflected light is determined by the refractive index value (distribution) of the cholesteric liquid crystal and the thickness of the refractive index changing layer, that is, the interval between layers of the multilayer structure.
The cholesteric liquid crystal is formed into flakes (this state is referred to as a cholesteric liquid crystal pigment), and a color variable ink composition is obtained by the same method as that for the pearl pigment.
The color variable ink layer is formed on the surface of a plastic film or the like by using the color variable ink composition, or an appropriate method such as various printing methods directly on the surface of the security object. It is formed by.
The color variable ink composition of the present invention functions as a color variable ink layer.

(Main applications)
The main use of the color variable ink composition of the present invention is as a counterfeit prevention field, specifically, a credit card or the like that can damage a cardholder or a credit card company when used forgery. , Identification card such as driver's license, employee ID card, membership card, admission ticket for entrance examination, passport, banknote, gift certificate, point card, stock certificate, securities, lottery ticket, horse ticket, bank passbook, boarding pass, pass There are tickets, air tickets, admission tickets for various events, play tickets, transportation and prepaid cards for various telephones.
All of these are information records that hold information of economic or social value, identity identification, etc., and can identify the authenticity of the record itself for the purpose of preventing damage caused by forgery. Although it is desired to have a function, the present invention is applied to a method in which the confirmation method is visual and it is particularly desired to have a function to prove the authenticity of the visual determination.
In addition to the uses described above, expensive products such as luxury watches, luxury leather products, precious metal products, jewelry, etc., often referred to as luxury brand products, or storage boxes for these expensive products And cases can also be forged. In addition, mass-produced products of famous brands, such as audio products, electrical appliances, etc., or tags that are hung on them are also subject to forgery.
Furthermore, a storage body in which music software, video software, computer software, game software, or the like, which is a copyrighted work, or cases thereof can also be forged. In addition, it is desirable that products such as printer toner, paper, and the like in which supplies to be replaced are limited to genuine materials have a function of identifying their authenticity for the purpose of preventing damage caused by forgery.
A forgery prevention body or the like that can be visually judged is added to these things in a form such as sticking, and the authenticity of the security object is proved by the visual judgment.
In the present specification, “ratio”, “part”, “%” and the like indicating the composition are based on mass unless otherwise specified, and the “/” mark indicates that they are integrally laminated.

(Background technology)
Conventionally, in order to prevent forgery of this kind of cash vouchers, forgery prevention technology has been performed in which a color variable printing layer whose color changes depending on the viewing angle is provided. Such a color variable printing layer is a color variable ink whose color changes depending on the viewing angle, such as pearl ink, and is formed by printing or the like. The ink whose color changes includes a pigment that multi-reflects light, and the color appears to change due to interference of light reflected by the pigment. Therefore, the color change effect increases as the amount of light reflected by the pigment increases. Therefore, the color variable printing layer is often printed by stencil printing such as screen printing or intaglio printing such as gravure printing so that the thickness of the color variable printing layer is increased so that the number of pigments that multiple reflect light is increased. .
Specifically, forgery prevention that provided a color variable printing layer such as pearl printing on printing media such as gift certificates, stock certificates, etc., and concealed a part of the color variable printing layer in a pattern so as not to be visible, forming specific information Print media has been proposed. (For example, refer to Patent Document 1).
This print medium has a feature that the color tone of the medium base material and the color tone of the specific information appear to be synchronized. However, general pearl ink itself can be obtained unless its optical performance is specified, and if it is a normal printing manufacturer, pearl ink is obtained and matte ink is printed thereon. Thus, it is possible to make a similar printed matter.

Therefore, in order to further improve anti-counterfeiting, a color variable printing layer whose color changes depending on the viewing angle, and a photoreactive printing layer that emits fluorescence by irradiation of ultraviolet rays or infrared rays on the color variable printing layer are provided in a pattern. At least a portion of the printed portion using an anti-counterfeit printing medium (for example, see Patent Document 2), or an anti-counterfeit ink composition containing at least a pearl pigment and a fluorescent pigment whose color tone is changed by ultraviolet irradiation or infrared irradiation. However, forgery prevention printed matter (for example, see Patent Document 3) having a configuration in which a single color or a plurality of colors are printed is known.
In addition, as another pigment having pleochroicity depending on the observation angle as described above, for example, a composition comprising a cholesteric liquid crystal, a three-dimensional crosslinkable resin, a photoinitiator, and the like is applied to a plastic film by a doctor. There is a method of using a liquid crystal pigment or the like obtained by aligning and forming by a shear gradient at the time of peeling, and then peeling and crushing from a plastic film. (For example, refer to Patent Document 4).
The above-mentioned pigment has a feature that the hue varies depending on the viewing angle and the reflected light is circularly polarized. Depending on the normal copying means, it is not possible to make the duplicates have such optical characteristics. Therefore, it is very effective to use liquid crystal pigments for preventing counterfeiting of securities and credit cards. In addition, since the hue changes depending on the observation angle, there is a feature that an excellent design can be obtained.

JP 2000-006564 A JP 2002-274000 A JP 2002-285061 A JP 1994-220350

However, in these pigments showing color variability, the basic principle of color variability is that for pearl pigments and effect pigments, natural mica flakes (mica flakes), alumina flakes, silica flakes, On the surface of the silicate glass flakes, a transparent metal oxide thin film having a thickness smaller than the visible light wavelength and a refractive index larger than those of the transparent substrate is formed, and the light incident on the pigment is multiplexed in the thin film. The wavelength of the reflected light is made selective by reflection and the interference phenomenon.
In other words, when the light is multiple-reflected, the multiple reflected light causes an interference phenomenon, and the reflected light wavelength is transparent due to the fundamental property of light that concentrates the reflected light wavelength and increases its intensity. It is automatically determined depending on the refractive index value and thickness of the metal oxide thin film, and the “color changes” and the “change pattern” (degree of change, range of change, etc.) are also uniquely determined.
Due to the effect of this multiple reflection, the “change pattern” is as follows. That is, it enters the thin film perpendicularly (“angle 0 °” with respect to the reference direction), and is incident perpendicularly, for example, at an angle of 45 degrees, and again 45 in the opposite direction. The wavelength of light that is selectively reflected differs greatly from the case of light that reflects at a degree, and “45-degree reflected light (after 45 degrees incidence)” differs from “vertically reflected light (after perpendicular incidence)” Theoretically, the wavelength value is 0.71 times (from cos 45 ° / cos 0 ° ≈0.71).
That is, in a certain pigment, if the vertically reflected light (after normal incidence) is 700 nm (red), the 45 degree reflected light (after 45 degrees incident) becomes 490 nm (blue). A so-called “blue shift” occurs.
This is a basic property of “transparent thin film” (transparent metal oxide thin film in pearl pigment), and the color change is monotonously changed from long wavelength to short wavelength according to this theory (“blue shift”). To do.
That is, the color of the vertical reflected light and the color of the 45 ° or 70 ° reflected light are uniquely determined by the thickness of the transparent metal oxide thin film layer, the refractive index value, and the like. It is the same. Therefore, even when the above-described various color variable inks are used, the color change situation is the same. As a result of the popularization of these pigments, the same color change is confirmed. Therefore, it can no longer be said that it has anti-counterfeiting properties.
In addition, the liquid crystal pigment has a refractive index distribution in the liquid crystal itself, and this refractive index distribution has the same function as the above-described thin film, and therefore exhibits the same selective reflectivity. Accordingly, the wavelength change of the reflected light becomes “blue shift” as in the thin film.
As described above, since all of the “color variable inks” are “blue shifted” at the same rate of change, even if various color variable inks are applied to the security object, they are visually observed. As described above, the appearance is almost the same, and the security is somewhat inferior in terms of anti-counterfeiting effect by visual determination.

Accordingly, the present invention has been made to solve such problems. The object is to provide a color variable ink that exhibits a color change not found in conventional color variable inks. That is, the “blue shift” that is the basic principle of the transparent thin film is not performed, for example, “blue shift” is exhibited as vertical reflected light, and “red” is exhibited as reflected light near 70 degrees. coloration and, and provides less color variable ink scattering light to be suitable for anti-counterfeiting applications.

To solve the above problem,
The first aspect of the present invention is:
In a color variable ink composition containing a pigment whose wavelength of selectively reflected light changes according to the incident angle of light to be observed, when the incident angle changes from 0 degrees to 70 degrees, The wavelength of the selectively reflected light includes a pigment that shifts from a visible region of 500 nm or less to an ultraviolet region, and a pigment that shifts from an infrared region to a visible region of 500 nm or more.
According to a first aspect of the invention,
In a color variable ink composition containing a pigment whose wavelength of selectively reflected light changes according to the incident angle of light to be observed, when the incident angle changes from 0 degrees to 70 degrees, The wavelength of the selectively reflected light is composed of a pigment that shifts from a visible region of 500 nm or less to an ultraviolet region, and a pigment that shifts from an infrared region to a visible region of 500 nm or more. An ink composition is provided.
Pearl pigments, effect pigments, etc. are fine flakes and theoretically calculated when the flat surface of the flake is parallel to the surface formed by the color variable ink layer when it becomes a color variable ink layer. However, when the flakes are directed in various other directions, the incident angle and the reflection angle of the light on the transparent oxide thin film formed on the flakes are different. As a result, various colors of reflected light (hereinafter referred to as scattered light) are generated in directions other than a predetermined reflection angle.
Further, the incident light may pass through a plurality of flakes and finally appear as reflected light. The shape of the flake itself, the properties of the flake surface, the refractive index and its distribution also affect the reflection on the flake surface and the attenuation of transmitted light.
However, light that has passed through a plurality of flakes has a large attenuation, has little effect on visual observation, and an angle at which the light is regularly reflected with respect to the incidence of light at a predetermined incident angle. Since only the light that has passed through a predetermined path reaches the reflected light that comes out of the light, the wavelength selection process is limited, and as a result, only light having a predetermined wavelength is reflected.
In order to ensure the intensity of light of this predetermined wavelength and reduce unnecessary scattered light, the flake shape is flat, the flake surface is smooth, the transparent oxide thin film has a uniform thickness, and the color variable ink layer The flakes that are parallel to the ink layer forming surface have a large proportion, and the light incident on the ink layer is reflected only by one or two flakes, and the ink is reflected as reflected light. Design to come out of the layer.

In the visual observation, since this scattered light becomes an obstacle to determination, the formation method is devised so that the flakes are parallel to the surface formed by the color variable ink layer when the color variable ink layer is formed. For example, a flat pigment (a disk shape with a flatness ratio of 2 to 5. The flatness ratio is an ellipsoid, and is a value obtained by dividing the major axis length by the minor axis length. When the flatness ratio is 5 or more, the pigment is deformed in the inking process and the scattered light also increases.), And the pigment size (average particle diameter) is, for example, 10 μm, When the thickness of the color variable ink layer after drying is ½ or less, the ratio of the pigment in the inclined state decreases, and many of them are parallel to the color variable ink layer. Furthermore, as a method of forming the color variable ink layer, as in blade coating, a printing pressure is applied in the coating direction, and during coating, a color variable ink layer is formed with a low viscosity, and the time for flakes to overlap with its own weight is set. After securing, the scattered light can be reduced by making various solvent evaporations at the time of drying and suppressing the flakes being pushed up during the evaporation.
Accordingly, when composing the ink composition, depending on the printing method employed, the solvent ratio is 50% to 90%, and the solid content (color variable ink layer forming component, consisting of pigment, resin and additive). Of these, the pigment ratio is 10% to 50%. In order to obtain a predetermined reflected light intensity, mixing of 10% or more is necessary. However, if it exceeds 50%, the interaction between pigments such as aggregation between pigments works strongly, and the surface of the color variable ink layer is formed. It becomes difficult to become parallel to.
When the color variable ink layer forming method is an ultraviolet ray curing method or an electron beam curing method, the color variable ink can be made to have a low viscosity and the color variable ink layer is cured without using almost any solvent. Since it is possible to secure the time until the flakes are made, it becomes easy to perform the process of aligning the flakes, such as securing the time of overlapping with its own weight or performing a calendar process.
Since the flakes used in the present invention are transparent, they are particularly suitable for these ionizing radiation forming methods.

Of course, the affinity between the pigment and the resin is important. The better the adhesiveness, the simpler the reflection / transmission (refraction) at the pigment / resin interface, and the less the scattered light. When the surface of the pigment is not a smooth surface, complicated reflection and transmission (refraction) occur at the interface, and light travels in various directions. Since the reflection at this interface is a portion that does not contribute to the wavelength selectivity due to multiple reflection in the transparent metal thin film layer of the present invention, it is desirable that this surface simply transmit. That is, it is desirable that the surface is smooth, has little reflected light, and that almost all incident light simply passes through this surface.
For this purpose, it is desirable that the difference in refractive index between the resin and the transparent metal thin film is small. For example, for a transparent metal thin film having a refractive index of 1.80 or more, the refractive index of the resin is 1.40 or more, preferably Is preferably 1.60 or more.
However, since there is no transparent resin having a refractive index near 1.80, conversely, a transparent metal thin film having a low refractive index, for example, a refractive index of 1.50 is used, and a resin having the same refractive index is adopted. Thus, unnecessary reflection at the interface between the resin and the transparent metal thin film can be almost eliminated.
Examples of the resin include polymethyl acrylate (n = 1.47), polyvinyl acetate (n = 1.47), polyvinyl chloride / vinyl acetate (n = 1.54), melamine resin (n = 1.56), An epoxy resin (n = 1.61), a phenol resin (n = 1.60), or a mixture thereof can be used as appropriate.
The optimum solvent is selected depending on the color variable ink layer forming method.
As the solvent, esters, ethers, alicyclic hydrocarbons, aliphatic hydrocarbons, aromatics, alcohols, and the like and mixtures thereof are used.
These are classified into low boiling point solvents (boiling point 100 ° C or lower), medium boiling point solvents (boiling point 100 ° C to 150 ° C), and high boiling point solvents (boiling point 150 ° C or higher) according to the boiling point. Adjust the flakes to be parallel to the surface of the color variable ink layer, such as mixing with boiling point solvents and devising to gradually dry out while suppressing rapid solvent volatilization.
Furthermore, in consideration of transparency, various additives, dispersants, leveling agents, lubricants, plasticizers, coupling agents, antifoaming agents, ultraviolet absorbers, various curing accelerators and the like are used.
The color variable ink forming method is used in various methods such as offset printing, letterpress printing, gravure printing, nozzle printing, curtain coat printing, silk screen printing, intaglio printing, inkjet printing, etc. in order to fully demonstrate the functions of the present invention. The solvent composition, ink viscosity adjustment and drying / curing methods can be devised.
Of course, in consideration of the environment, it is also suitable to use a water-based ink composition using a water-soluble resin such as polyvinyl alcohol.

As pearl pigments and effect pigments,
Natural mica flakes (mica flakes), etc., pigments coated with metal oxides such as titanium oxide and iron oxide, synthetic alumina flakes (particle size 1-30 μm, thickness 0.5 μm-5 μm), synthetic silica flakes (particle size 5-30 μm, thickness 0.5 μm-5 μm), borosilicate glass flakes coated with titanium oxide (particle size 10-30 μm, thickness 0.5 μm-5 μm), synthetic mica flakes (aluminum oxide, magnesium oxide, silicon dioxide, A pigment in which a metal oxide such as titanium oxide or iron oxide is coated (coated with 50 nm to 400 nm) on a fluorine compound or the like can be used.
Artificially synthesized materials are preferable because they have a sharp particle size distribution with little variation in particle size, a smooth surface, and a uniform shape.
Moreover, if the thickness of the bright metal thin film formed on the flake surface is not a predetermined thickness, the wavelength of light reflected to a predetermined reflection angle is shifted. For this reason, the variation in the thickness of the transparent metal thin film on the flakes needs to be within ± 20%, and further within ± 10%. At 20%, the wavelength variation is almost 17%. At 10%, it is about 10%.
Of course, this wavelength changes depending on the refractive index variation of the transparent metal thin film, but the accuracy of formation by the liquid phase method or the CVD method (compound vapor deposition method) is very high, which affects the color change of the present invention. There is not much variation.
When this transparent metal thin film is made of titanium dioxide (the refractive index changes depending on the degree of oxidation) and the thickness is 90 nm to 100 nm, the vertical reflected light becomes the infrared region, and the color changes even when observed from the vertical direction. Although it cannot be recognized, red reflected light (“red”: 620 nm to 750 nm) is exhibited by reflected light of 60 to 70 degrees, and thus red can be recognized in oblique observation.

When this thickness is set to 300 nm to 330 nm, the vertical reflected light becomes blue (“blue”: 450 nm to 495 nm), but when the observation angle is increased, the reflected light enters the ultraviolet region, so the color is no longer recognized. Can not do.
Therefore, when the transparent metal thin film formed on the flake surface is an ink in which titanium oxide having a thickness of 100 nm and 300 nm are mixed, and an ink layer is formed using the ink,
It is possible to create a color variable ink that exhibits “blue” as the vertical reflected light and exhibits “red” when observed at 70 degrees, that is, “red shift”.
When the color variable ink layer is formed, if each pigment is evenly distributed, the switching performance becomes clear, so by changing the size of the flakes, small flakes in the gaps of large flakes It is desirable that the particle size is adjusted so that the vertical cross-sectional area (the area of the reflecting portion viewed from the observation side) is substantially the same.
Of course, the color change of “Red Shift” is emphasized by “Blue”, and when the observation angle is increased, the mixture ratio etc. are adjusted according to various variations such as slightly showing “Red”. To do.
In addition, the amount of reflected light from the pigment for “blue” is changed in order to make the change characteristic, such as interpolating the change from “blue” to “red” to make the change smooth. , In addition to adjusting the amount of reflected light from the “red” pigment (adjusting the reflected area, ie, adjusting the sum of the flat areas of the flat pigment), the reflected wavelength range is relatively narrow, It is also preferred to add pigments exhibiting a color between "blue" and "red". For example, “green” is used. In this case, a pigment that causes Bragg reflection is added only at a reflection angle of 30 to 40 degrees. As will be described later, this is obtained by a liquid crystal pigment having a strong selective wavelength. It can also be obtained by making the transparent metal thin film of pearl pigment and effect pigment into a multilayer.
Furthermore, since the intensity of reflected light reflected at a specific reflection angle such as “blue” or “red” can be controlled by the shape and amount of the color variable pigment, only the genuine ink manufacturer knows how to do “blue shift”. High anti-counterfeiting effect can be obtained by making it complicated.
As described above, when the incident angle changes from 0 degree to 70 degrees, the wavelength of the selectively reflected light of the pigment is
A pigment that shifts from the visible region of 500 nm or less to the ultraviolet region and a pigment that shifts from the infrared region to the visible region of 500 nm or more are mixed, and an appropriate resin, solvent, and additive are added to aggregate the pigment. Dispersion treatment for unraveling is performed to obtain the color variable ink of the present invention.
In particular, when two types of pigments are prepared by the same manufacturing method, only the thickness of the transparent oxide thin film is different, and the flakes have the same size, shape, etc. Therefore, the composition and the pigment distribution in the ink layer can be maintained uniformly during the production of the color variable ink composition and further during the formation of the color variable ink layer.

As the liquid crystal pigment, a three-dimensional cross-linking substance having a liquid crystal structure having a chiral phase can be used. As the liquid crystal substance having a chiral phase, various cholesteric liquid crystals can be used, and the liquid crystal substance can be manufactured by adding a chiral substance to a nematic, smectic, or discotic structure.
The three-dimensional crosslinkable resin has a polymerizable group, a polycondensable group, or a group capable of polyaddition, and a part of these groups is preferably a polyfunctional group having two or more functions. For example, a methacryloxy group or an acryloxy group. More preferred three-dimensional crosslinkable resins include polyorganosiloxane.
Both of the above are mixed and then reacted by heating under reflux to isolate the product. The resulting product is further melt-mixed with a photopolymerization initiator to form a coating composition. This coating composition is hot-melt coated on a polyethylene terephthalate resin film, oriented by a doctor, and then irradiated with ultraviolet rays. Is applied to crosslink the coating film, the crosslinked coating film is separated from the film, and finally pulverized into a liquid crystal pigment.
For the purpose of improving the dispersibility in the ink composition, the liquid crystal pigment may have an organic polymer, oligomer, or low molecular dispersant of about 0.01 mg / m 2 or more on the surface of the liquid crystal pigment. Good.
Cholesteric liquid crystals are induced by adding a small amount of an optically active substance (chiral agent) to nematic liquid crystals, and have a spiral structure with a constant period with respect to the reference direction, thereby showing a refractive index change in the liquid crystal layer. Are layered. The multilayer structure having this refractive index distribution has a property of reflecting the incident light for observation after selecting the wavelength at a predetermined angle.
The wavelength of the selectively reflected light is determined by the refractive index (distribution) of the cholesteric liquid crystal and the interval between the refractive index changing layers. This interval is adjusted by the molecular length of the three-dimensional crosslinkable resin, the position of the functional group, the addition amount of the chiral substance, and the like.
Accordingly, the liquid crystal itself has a refractive index distribution, and this refractive index distribution is formed by laminating the above-described thin films in multiple layers (the portion where the twist of the cholesteric liquid crystal goes around is one layer, and this layer is repeatedly present). By producing the same effect as that of the thin film, selective reflectivity is exhibited, and the wavelength of the reflected light “blue shifts” like the thin film.

However, when the number of layers increases, “Bragg reflection” occurs, and only a single wavelength (meaning that the width of the reflected wavelength is narrowed) is reflected at a predetermined angle. Therefore, the thickness of the liquid crystal pigment is set so that the refractive index distribution in the liquid crystal pigment is 3 or more and 20 or less (one layer is 200 nm to 1000 nm), and the incident angle is 0 degree to 70 degrees. It is assumed that it has necessary reflected light. If the number of layers is less than 3, the wavelength selectivity is insufficient, and if it exceeds 20, the width of the reflection wavelength is 50 nm or less, and the reflection angle is limited. Preferably, when the number is 5 layers or more and 10 layers or less, the wavelength selectivity and the width of the reflection angle are desired.
That is, when the incident angle of the light to be observed changes from 0 degree to 70 degrees, the wavelength of the selectively reflected light shifts from the visible region of 500 nm or less to the ultraviolet region. The reflection conditions need to be relaxed, and the situation can be shifted from the infrared region to the visible region of 500 nm or more by the same method. Of course, it is not necessary to emit strong reflected light over the entire range of the predetermined angle, and when the authenticity of the continuity of the color change is determined, it is set so that the continuity can be recognized.
The cholesteric liquid crystal (resined due to curing or the like) is made into flakes, and the selection of the pigment is performed when the incident angle of light to be observed changes from 0 degrees to 70 degrees as in the case of pearl pigment The pigment that shifts the wavelength of reflected light from the visible region of 500 nm or less to the ultraviolet region and the pigment that shifts from the infrared region to the visible region of 500 nm or more are mixed to obtain a color variable ink composition.
Various resins for ink can be used as the resin for converting the liquid crystal pigment into an ink. In particular, an ionizing radiation curable resin is preferred because of its high curability and physical properties. As the ionizing radiation curable resin, aliphatic acrylates, cycloaliphatic acrylates, and acrylics such as these methacrylates can be used. Furthermore, a vinyl photopolymerizable monomer or oligomer can be used.
In addition, rosin and other natural resins, soybean oil-modified alkyd resins, and other oxidative polymerizable resins, acrylic resins, polyesters, polyvinyl acetate, melamine resins, epoxy resins, phenol resins, etc. Alternatively, a mixture or copolymer of these can be used as appropriate.
As other additives, those similar to the color variable ink composition using a pearl pigment or the like can be used.
When these color variable ink compositions are used to form a color variable ink layer by an appropriate printing method, when the incident angle of light to be observed changes from 0 degrees to 70 degrees, the wavelength of the reflected light is Observed as if "Red-shift".

The second aspect of the present invention is:
The mixing ratio of the pigment that shifts from the visible region of 500 nm or less to the ultraviolet region and the pigment that shifts from the infrared region to the visible region of 500 nm or more is 9/1 to 5/5. .
According to the second aspect of the present invention,
The mixing ratio of the pigment that shifts from the visible region of 500 nm or less to the ultraviolet region and the pigment that shifts from the infrared region to the visible region of 500 nm or more is 9/1 to 5/5, A color variable ink composition can be provided.
Usually, when observing the color variable ink layer, first, it is often observed from the vertical direction. Therefore, the color variable ink layer first exhibits red, and changes to blue when the observation angle is changed. That is, “blue shift” is observed.
Therefore, when observing in the vertical direction, blue is displayed from the beginning, changing the angle a little, entering the invisible region (ultraviolet region), and when the color disappears, the observation is terminated at that point, and the observation angle is further increased, It is hard to notice that it becomes 60 degrees to 70 degrees, and again exhibits “red” which is another color.
That is, the unexpectedness can be enhanced by making the pigment exhibiting “red” less than the pigment exhibiting “blue” and reducing it to the same amount or less and further to 1/9.
However, if the ratio is less than 1/9, the “red” coloring itself becomes unstable and is not suitable for authenticity determination.

As described above, when the observation angle is changed after exhibiting “blue”, the invisible region (the ultraviolet region portion and the infrared region portion overlap each other to a certain large angle, that is, about 50 to 70 degrees, and the color disappears. It is also preferable to design so that it suddenly appears “red” when it is further tilted. The anti-counterfeiting property, that is, the stronger the degree of disappearance of the color (the more no color is caused by scattered light and the colorless state continues), the higher the forgery prevention property is.
The shapes of the pigments to be mixed can be the same or similar, and the mixing ratio can be uniform over the entire color variable ink layer. That is, although the optical characteristics are different, the physical shape is the same, so that the dispersibility in the ink is the same, and the mixing ratio does not change after the ink layer formation process or after the ink layer formation.
Further, the size of the pigment that shifts from the infrared region to the visible region of 500 nm or more from the infrared region to the ultraviolet region with respect to the size of the pigment that shifts from the visible region of 500 nm or less to the ultraviolet region. 10 (the volume ratio is the third power), a small pigment can enter a gap where a large pigment contacts in one plane, and so-called “close-packing” can be achieved. Less stable color change can be obtained.
The stability of these “color changes” improves the reliability of authenticity proof in authenticity determination.
The method described above can be appropriately used as the ink composition.

According to the present invention,
In a color variable ink composition containing a pigment whose wavelength of selectively reflected light changes according to the incident angle of light to be observed, the selection of the pigment is performed when the incident angle changes from 0 degrees to 70 degrees. The wavelength of the reflected light is
It changes from “blue” and exhibits “red”. In other words, a novel color variable ink exhibiting “red shift” can be provided.
Due to its novelty, it can be applied to various security products to prove its authenticity.
Further, by adjusting the mixing ratio of the pigments, it is possible to adjust the color change, to bring about an unexpected color change and the like, and to further improve the anti-counterfeiting property.

1 is a cross-sectional view of a color variable ink layer showing an embodiment of the present invention, in which light to be observed is incident perpendicularly to the color variable ink layer forming surface (reference direction) and reflected light is reflected vertically. It is. It is sectional drawing of the color variable ink layer which shows one Example of this invention, Comprising: The light to observe enters with a big angle with respect to the reference direction of a color variable ink layer formation surface, and the reflected light is as large as an incident angle It is the figure currently reflected in the opposite direction.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(Color variable ink composition)
The color variable ink composition of the present invention contains two types of pigments having different optical characteristics. These two types of pigments are pigments that change the wavelength of light that is selectively reflected according to the incident angle of light to be observed, and are dispersed in an appropriate resin, solvent, or the like as a color variable ink composition. Formed on the surface of a plastic film or the like to form an anti-counterfeit body, or formed directly on the surface of the security object by various methods such as various printing methods, thereby forming a color variable ink layer. It is used for authenticity determination by visual observation and authenticity verification.
(Color variable pigment)
The color variable pigment used in the present invention is:
As the incident angle of the light to be observed on the color variable ink layer changes from 0 degrees to 70 degrees, it is selectively reflected at each pigment and finally as the light exiting from the color variable ink layer. The wavelength of the light to be transmitted consists of a pigment that shifts from the visible region of 500 nm or less to the ultraviolet region, and a pigment that shifts from the infrared region to the visible region of 500 nm or more.
As the pigment, a pearl pigment, an effect pigment, and a liquid crystal pigment are used.
As a pearl pigment,
Merck Iriodin 100 Silver Pearl, 103 Rutile Sterling Silver, 111 Rutile Fine Satin, 120 Raster Satin, 123 Bright Raster, 151 Rutile Pearl, 153 Flash Pearl, 163, Simmer Pearl, 183 Super Nova White, 201 Rutile Fine Gold, 211 rutile fine red, 221 rutile fine blue, 223 rutile fine lilac, 231 rutile fine green, 205 rutile platinum, 215 rutile red pearl, 217 rutile red pearl, 219 rutile lilac pearl, 225 rutile blue pearl, 235 rutile green pearl, 249 Flash Gold, 259 Flash Red, 289 Flash Blue, 299 Flash Green, 300 Gold Ludo Pearl, 302 Gold Satin, 303 Royal Gold, 306 Olympic Gold, 309 Medallion Gold, 320 Bright Gold, 323 Royal Gold, 351 Sunny Gold, 355 Glitter Gold, 500 Bronze, 502 Red Brown, 504 Red, 505 Red Violet, 507 Sheila Bread, 520 bronze satin, 522 red brown, 524 red satin, 530 glitter bronze, 532 glitter red brown, 534 glitter red, etc. are used.

Further, Pearl Glaze MM-100R, MF-100, MF-100RN, ME-100, MS-100R, MY-100RF, MRB-100RF, MV-100RF, MB-100RF, MG-100RF, MC-, manufactured by Sano Paint Co., Ltd. 302, MC-323R, MC-326R, MC-520, MC-522, MC-524, etc.
BASF Corp. DESERT REFLECTIONS CANYON SUNSET, DESERT REFLECTIONSPAINTED DESERT PLUM, TIMICA SILK WHITE, TIMICA NU-ANTIQUE SILVER, FLAMENCO SATIN BLUE, FLAMENCO SATIN PEARL 3500, CLOISONNE RED, CLOISONNE VIOLET, CLOISONNE BLUE, CLOISONNE SATIN BRONZE, SATAIN BLUE, DUOCROME RO , DUOCROME RO, DUOCROME VB, GEMTONE GARNET, GEMTON MAUVE QUARTZ, CELLINI RED, CELLINI BLUE, REFLECKS AYS OF RED, REFLECKS BEAMS OF BLUE, CHROMA-LITE DARK BLUE, CHROMA-LITE MAGENTA, COSMICA BLUE, RED, ORANGE or the like is used.
As an effect pigment,
SILALIC F60-50SW FIREDIDE COPPER, F60-51SW RADIANT RED, T60-10SW CRYSTAL SILVER, T60-20 SW SUNBEAME GOLD, T60-21 SW SOLARIS RED, T60-23 SWGAL ELG T60-22 WNT AMETHYST DREAM, T60-25 SW COSMIC TURQUIOISE, etc.
Also, Merck Color Stream F20-00WNT AUTAMN MYSTERY, F20-01 WNT VIOLA FANTASY, F20-02 Arctic FIRE, F20-03 TROPIC SUNRISE, F20-03 LAPIS SUNLIGHT H
Merck's bi-flare 49, 83, 84, L200, Minatech 230A-IR, Pyrisma T40-20SW YELLOW, T40-21SWRED, T40-22 SW VIOLET, T40-23 BLUE, T40-24 GREEN, T40-25 TURQUIOISE, T40 -27 INDIGO etc.
In addition, Merck's Miraval SCENIC WHITE, SCENIC GOLD, SCENIC COPPER, SCENIC TURQOISE, MAGIC WHITE, MAGIC GOLD, MAGIC COPPER, MAGIC RED, MAGIC LILAC, MAGIC BLUE, MAGIC BLUE, MAGIC BLUE, MAGIC BLUE

(Cholesteric liquid crystal pigment)
The cholesteric liquid crystals used as the basis of cholesteric liquid crystal pigments include cholesterol halides, monocarboxylic acid cholesterol esters, monocarboxylic acid sitosterol esters, benzoic acid derivative cholestanol esters, dibasic acid dicholesteryl esters, Examples thereof include molecular compounds, side chain type liquid crystal polymer compounds, and rigid main chain type liquid crystal polymer compounds.
More specifically, for example, cholesteryl chloride, cholesteryl acetate, cholesteryl nonanoate, methyl carbonate, ethyl cholesterol, cholesteryl p-methoxybenzoate, sitosteroyl benzoate, sitosteroyl p-methyl benzoate, cholestanyl benzoate, 10, 12- Docosadiin dicarboxylic acid dicholesteryl ester, 8,12-eicosadicarboxylic acid dicholesteryl ester, 10,12-pentacosadiin dicarboxylic acid dicholesteryl ester, dodecadicarboxylic acid dicholesteryl ester, 12,14-hexacosadiin dicarboxylic acid Dicholesteryl ester, 4- (7-cholesteryloxycarbonylheptyloxy) phenoxyoctanoic acid cholesteryl ester, L-glu Min acid -γ- benzyl / L-glutamate -γ- dodecyl copolymers and the like.
Further, cholesteryl formate, cholesteryl acetate, cholesteryl propionate, cholesteryl butyrate, cholesteryl pentanate, cholesteryl hexanate, cholesteryl heptanoate, cholesteryl octanate, cholesteryl nonanoate, cholesteryl decanate, cholesteryl decanate (cholesteryl laurate) Cholesteryl myristate, cholesteryl palmitate, cholesteryl stearate, cholesteryl oleate, cholesteryl oleyl carbonate, cholesteryl linoleate, cholesteryl 12-hydroxystearate, cholesteryl mercaptan, cholesterol chloride, cholesteryl fluoride, cholesteryl bromide, cholesteryl iodide, etc. Can be mentioned.
Preferably, a mixture of three kinds of alkyl cholesterol (for example, cholesterol nanoate) and cholesteryl halide (for example, cholesterol chloride) cholesteryl oleyl carbonate is used, and these three types of liquid crystals are used so as to be used at room temperature. Is common.
In addition, it is not limited to the compound shown here, Moreover, these cholesteric liquid crystal compounds can be used 1 type or in mixture of 2 or more types.
As a liquid crystal compound in which a chiral compound is added to a nematic liquid crystal compound, 4-substituted benzoic acid 4′-substituted phenyl ester, 4-substituted cyclohexanecarboxylic acid 4′-substituted phenyl ester, 4-substituted cyclohexane Carboxylic acid 4′-substituted biphenyl ester, 4- (4-substituted cyclohexanecarbonyloxy) benzoic acid 4′-substituted phenyl ester, 4- (4-substituted cyclohexyl) benzoic acid 4′-substituted phenyl ester, 4- (4- Substituted cyclohexyl) benzoic acid 4'-substituted cyclohexyl ester, 4-substituted 4'-substituted biphenyl, 4-substituted phenyl 4'-substituted cyclohexane, 4'-substituted cyclohexane, 2- (4-substituted phenyl) -5-substituted pyridine Etc. are used.

Further, a liquid crystal compound having a cyano group or a fluorine atom at least at one end of the molecule and various suitable chiral agents added to these liquid crystal compounds are used. As the chiral compound, “CB-15”, “C-15” (manufactured by BDH), “CM-21”, “CM-22”, “CM-19”, “CM-20”, “CM” (Above, manufactured by Chisso Corporation), "S1082", "S-811", "R-811" (above, manufactured by Merck & Co., Inc.), and the like.
Furthermore, a three-dimensionally crosslinkable liquid crystalline polymerizable monomer molecule or polymerizable oligomer molecule can be used. A layer containing cholesteric liquid crystal molecules can be obtained by adding an arbitrary chiral agent to a predetermined polymerizable monomer molecule or polymerizable oligomer molecule.
Examples of the three-dimensionally crosslinkable monomer molecule include a mixture of a liquid crystal monomer and a chiral compound as disclosed in, for example, JP-A-7-258638 and JP-T-10-508882. As a more specific example, for example, liquid crystalline monomers represented by the following general chemical formulas (1) to (11) can be used. In the case of the liquid crystalline monomer represented by the general chemical formula (11), X is preferably an integer in the range of 2 to 5.

Moreover, as a chiral agent, a chiral agent as shown, for example by the following general chemical formula (12)-(14) can be used. In the case of the chiral agent represented by the general chemical formulas (12) and (13), X is preferably an integer in the range of 2 to 12, and the general chemical formula (1
In the case of the chiral agent represented by 4), X is preferably an integer in the range of 2-5.

When oligomer molecules are used, a cyclic organopolysiloxane compound having a cholesteric phase as disclosed in, for example, JP-A-57-165480 can be used. For example, a cholesteric liquid crystal layer can be obtained by adding about several to 10% of a chiral agent to polymerizable monomer molecules or polymerizable oligomer molecules.
Further, a cholesteric liquid crystal having no cholesterol group in which a group having an asymmetric carbon is introduced into a terminal group of a nematic liquid crystal obtained by organic synthesis, or a mixed liquid crystal in which a Schiff nematic liquid crystal is added to a cholesterol derivative is also used. Furthermore, halogen substitution products and esterified products of natural cholesterol (cholesteryl benzoate, cholesteryl chloride, cholesteryl oleate, cholesteryl nonanoate, and the like are also suitable.
Particularly preferably, it has a liquid crystal structure having a chiral phase formed by adding a chiral substance to a nematic, smectic, or discotic structure, and has a polymerizable group, a polycondensable group, or a group capable of polyaddition. For example, an oriented three-dimensional cross-linking substance having a bifunctional or higher polyfunctional group such as a methacryloxy group or an acryloxy group can be used. As the three-dimensional crosslinkable resin, polyorganosiloxane is most suitable because of its performance stability and workability.
Both of the above are mixed and reacted by heating under reflux to isolate the product. The resulting product is further melt-mixed with a photopolymerization initiator to form a coating composition. This coating composition is hot-melt coated on a polyethylene terephthalate resin film, oriented by a doctor, and then irradiated with ultraviolet rays. Is applied to crosslink the coating film, the crosslinked coating film is separated from the film, and finally pulverized into a liquid crystal pigment.
In any case, after forming into a film (resin) once, it is made into flakes through a fragmentation process such as crushing and cutting.
For the purpose of improving the dispersibility in the ink composition, those having an organic polymer, oligomer or low molecular dispersant of about 0.01 mg / m 2 or more on the surface of the liquid crystal pigment are also suitable.

(Pearl pigment inks)
Resins used for inks such as pearl pigments include polymethyl methacrylate (refractive index n = 1.49), polymethyl acrylate (n = 1.47), polybenzyl methacrylate (n = 1.57), polybutyl acrylate (N = 1.44), polyisobutyl acrylate (n = 1.48), cellulose nitrate (n = 1.54), methyl cellulose (n = 1.50), cellulose acetate propionate (n = 1.47) ), Polystyrene (n = 1.60), polyethylene terephthalate (n = 1.64), polyvinyl acetate (n = 1.47), polyvinyl chloride / vinyl acetate (n = 1.54), melamine resin (n = 1.56), epoxy resin (n = 1.61), phenol resin (n = 1.60), etc., or a mixture thereof can be used as appropriate. .
The optimum solvent is selected depending on the color variable ink layer forming method.
Solvents include esters: ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, isobutyl acetate, pentyl acetate, etc., ethers: ethyl ether, etc., ketones: methyl ethyl ketone, isobutyl ketone, methyl isobutyl ketone, glycol ether (Celsolve) ): Ethylene glycol monoethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monoethyl ether acetate, etc., alicyclic hydrocarbons: cyclohexanone, methylcyclohexanone, methylcyclohexanol, etc., aliphatic hydrocarbons: Normal hexane, etc., aromatics: toluene, xylene, etc., alcohols: ethanol, isopropyl alcohol, normal butanol, normal amyl alcohol , Isoamyl alcohol, using isobutanol and mixtures thereof.
These are classified into low boiling point solvents (boiling point 100 ° C or lower), medium boiling point solvents (boiling point 100 ° C to 150 ° C), and high boiling point solvents (boiling point 150 ° C or higher) according to the boiling point. Adjust the flakes to be parallel to the surface of the color variable ink layer, such as mixing with boiling point solvents and devising to gradually dry out while suppressing rapid solvent volatilization.
Furthermore, in consideration of transparency, various additives, dispersants, leveling agents, lubricants, plasticizers, coupling agents, antifoaming agents, ultraviolet absorbers, various curing accelerators and the like are used.
The color variable ink forming method is used in various methods such as offset printing, letterpress printing, gravure printing, nozzle printing, curtain coat printing, silk screen printing, intaglio printing, inkjet printing, etc. in order to fully demonstrate the functions of the present invention. The solvent composition, ink viscosity adjustment and drying / curing methods can be devised.
Of course, in consideration of the environment, it is also suitable to use a water-based ink composition using a water-soluble resin such as polyvinyl alcohol.

(Cholesteric liquid crystal pigment ink)
The following acrylic resins can be used as the ionizing radiation curable resin as a resin for converting the liquid crystal pigment into an ink. Namely, acrylic acid, aliphatic acrylate, allyl acrylate, allylated cyclohexyl acrylate, benzyl acrylate, bisphenol A diacrylate, epichlorohydrin modified bisphenol A diacrylate, ethylene oxide modified bisphenol A diacrylate, epichlorohydrin / ethylene oxide modified bisphenol A diacrylate , Ethylene oxide modified bisphenol S diacrylate, ethylene glycol acrylate, propylene glycol acrylate, butylene glycol acrylate, neopentyl glycol acrylate, butoxyethyl acrylate, epichlorohydrin modified aliphatic acrylate, cycloaliphatic acrylate, N, N- Dimethylaminoethyl acrylate, N-diethylaminoethyl acrylate, pentaerythritol tetraacrylate, pentaerythritol triacrylate, dipentaerythritol hexaacrylate, dipentaerythritol monohydroxypentaacrylate, alkyl-modified dipentaerythritol pentaacrylate, alkyl-modified dipentaerythritol tetraacrylate, alkyl-modified di Pentaerythritol triacrylate, caprolactone modified pentaerythritol hexaacrylate, ethylene oxide modified bisphenol A diacrylate, ditrimethylolpropane tetraacrylate, bisphenol epoxy acrylate, glycerol acrylate, glycidyl acrylate, oligoester acrylate, polyester Acrylate, phosphate type acrylate, ethylene oxide-modified phthalic acid acrylates, ethylene oxide-modified phthalic acid acrylate, epichlorohydrin-modified phthalic acid acrylate or urethane acrylate can be used.
Moreover, the following methacrylic type can also be used, and specifically, the corresponding methacrylic acid and the corresponding methacrylic acid ester listed above as the acrylic type can be used. In addition, as the ionizing radiation curable resin, a vinyl-based photopolymerizable monomer or oligomer such as N-vinylpyrrolidone can be used. As the ionizing radiation curable resin, one type or two or more types of monomers or oligomers of the substances described above can be used.

When an ionizing radiation curable resin is used as a resin and ultraviolet rays are used as ionizing radiation, a known photopolymerization initiator is blended. As the photopolymerization initiator, benzophenone-based, benzyl-based, benzoin-based, benzoic acid-based, thioxanthone-based, phenyl ketone-based, oxime-based organic low-molecular compounds, oligomers, or high-molecular compounds can be used. When the blending ratio is excessive, the degree of polymerization decreases. When the blending ratio is too small, the polymerization rate and the polymerization rate decrease. In any case, the drying characteristics and the film strength after printing. Etc. are preferably used at a mass ratio of 0.3 to 20 parts with respect to 100 parts of ionizing radiation curable resin which is a resin.
The particle size of the liquid crystal pigment is larger than the particle size of the pigment particles used in general lithographic inks and letterpress inks, so if you add too much, the fluidity of the ink may be poor or curability If the amount is too small, the color rendering effect as a pigment is reduced. Therefore, it is preferably used in a mass ratio of 5 to 100 parts with respect to 100 parts of ionizing radiation curable resin as a resin. Is preferred.
The following can be used for the oxidatively polymerizable resin as a resin for converting the liquid crystal pigment into an ink.
That is, natural resins such as rosin, cured rosin, rosin ester, rosin-derived maleic acid resin, or natural resin derivatives such as rosin-derived fumaric acid resin, phenol resin, rosin-modified phenol resin, rosin-modified xylene resin, fatty acid-modified xylene resin, A synthetic resin such as an oil-modified alkyd resin or soybean oil-modified alkyd resin can be used.
For the purpose of adjusting the viscosity and adjusting the drying speed, the above oxidatively polymerizable resin is usually blended with an oil component. Specific oils are obtained by processing vegetable oils such as linseed oil, linden oil, jute oil, hemp seed oil, safflower oil, soybean oil, palm oil, tall oil, castor oil, or cottonseed oil, or vegetable oil. Polymerized oils, processed oils such as maleic acid, or mineral oils such as machine oil or spindle oil can be used.
When using the oxidation polymerizable resin, various solvents or additives can be blended in addition to the oil. As the solvent, aliphatic hydrocarbon-based, aromatic hydrocarbon-based, alcohol-based, glycol-based, ester-based, or ketone-based solvents can be used. In addition, plasticizers (phthalate ester, adipic acid ester, or sebacic acid ester, etc.), wax (carnauba wax, wax, paraffin wax, polyethylene wax, polytetrafluoroethylene, etc.), dryer (cobalt, etc.) Or manganese metal soap), dispersant (polymer or low molecular surfactant, etc.), thickener (aluminum chelate, etc.), antifoaming agent (silicone, etc.), antioxidant (phenolic or An oxime type or the like), a leveling agent (silicone or the like), or an ultraviolet absorber (benzophenone type or triazole type or the like) can be used.

When using an oxidatively polymerizable resin as a resin, the vehicle component mainly composed of an oxidatively polymerizable resin, an oil component, and a solvent component generally has a higher acid value than an ionizing radiation curable resin. Since the compound itself exhibits a dispersant effect, the blending ratio of the liquid crystal pigment can be increased. However, since the liquid crystal pigment has a large particle size, if it is excessively mixed, the fluidity of the ink may be poor or the curability may be lowered. If it is too small, the color rendering effect as a pigment may be reduced. Preferably, it is preferably used in a mass ratio of 5 to 150 parts with respect to 100 parts of the total amount of the oxidatively polymerizable resin as a resin and the oil.
Further, acrylic resin, cellulose resin, polystyrene, polyester, polyvinyl acetate, melamine resin, epoxy resin, phenol resin, etc., or a mixture or copolymer thereof is appropriately used as a resin for forming a liquid crystal pigment into an ink. be able to.
As other additives, those similar to the color variable ink composition using a pearl pigment or the like can be used.
The same solvent as the color variable ink composition using a pearl pigment or the like can be used.
When these color variable ink compositions are used to form a color variable ink layer by an appropriate printing method, when the incident angle of light to be observed changes from 0 degrees to 70 degrees, the wavelength of the reflected light is Observed as if "red shift".
Since this “red shift” is designed in advance, the authenticity can be confirmed by a simple but reliable method by visually confirming this change.
Of course, if a change such as a good reflected light is inserted in the change as “red shift” or the reflected light is interrupted in the middle, it is no longer formed from the ink composition of the present invention. Even if the behavior of the reflected light of the color variable ink layer is analyzed in detail, it seems difficult to produce a color variable ink composition that exhibits the same behavior.

EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, it is not limited to this. In addition, except a solvent, each composition of each layer is a mass part of solid content conversion.
Example 1
A color variable ink composition was prepared using a pearl pigment as the color variable pigment 1.
As the color variable pigment 1, Iriodin type pigment B (manufactured by Merck & Co., Inc.) (made of natural mica flakes coated with 100 nm titanium oxide, particle size 5 to 25 μm, thickness 2 to 5 μm: 0 degree reflection 1500 nm, 70 degree reflection 700 nm) and Iriodin type pigment C (titanium oxide 300 nm coated on natural mica flakes, particle size 5 to 25 μm, thickness 2 to 5 μm: 0 degree reflection 450 nm, 70 degree reflection 200 nm) was mixed in the same amount to obtain the following ink composition. . In order to prevent the pigment from agglomerating and to uniformly disperse, it was treated with a ball mill containing 2 mm diameter glass beads for 30 minutes to obtain a color variable ink composition.
<Ink composition>
Pigment B 10 parts by mass Pigment C 10 parts by mass Urethane acrylate (refractive index n = 1.49) 30 parts by mass Ethyl acetate 20 parts by mass Isobutyl acetate 10 parts by mass Methyl isobutyl ketone 10 parts by mass Benzophenone photoinitiator 0.1 parts by mass Part This color variable ink composition is coated on a 25 μm thick PET film with a blade coating (coating while applying the blade share) to a thickness of 5 μm after drying, and cured by irradiating with ultraviolet rays, and the color variable ink layer A was obtained.
When the light 2 observed on the color variable ink layer A is in a direction perpendicular to the ink layer surface and the reflected light 3 is observed in substantially the same direction, a purple to blue color can be observed.
Further, when the light 2 to be observed is incident at an angle of 70 degrees from the direction perpendicular to the ink layer surface and the reflected light 3 that appears in the opposite direction at the same angle is observed, red can be observed. As a result, a so-called “red shift” was confirmed.
When this color variable ink layer formed product was applied as a small piece of 20 mm × 20 mm and applied on a credit card as a security object, the appearance by the observation angle was not the usual “blue shift”, Since it appeared as a so-called “red shift”, its authenticity could be confirmed very easily by visual observation.

(Example 2)
As effect pigments, Sirillac type pigment B (coating titanium oxide 40-60 nm on alumina flakes, particle size 15-30 μm, thickness 3-5 μm) and Sirillac type pigment C manufactured by the same company (titanium oxide 140- over alumina flakes) Example 2 was obtained in the same manner as in Example 1 except that the same amount of 160 nm coating, particle size of 5 to 10 μm, and thickness of 1 to 3 μm was mixed, and the color variable ink layer thickness was changed to 10 μm.
Although the effect was the same as that of Example 1, in the observation after pasting on the security object, the red color was observed more clearly than Example 1.
(Example 3)
Example 3 was obtained in the same manner as Example 2 except that the mixing ratio of Pigment B and Pigment C was 9/1.
The effect was the same as in Example 2, but the red reflected light was weak and could only be confirmed a little, but its presence could be confirmed with certainty, and its unexpectedness as a label affixed to the security object I was able to bring on.
Example 4
As the color variable pigment 1, a color variable ink composition using the following liquid crystal pigment was used.
<Color variable pigment B>
Germany Hecker HC Sapphire XS 20 parts by mass Germany Wacker Helicone HC Maple XS 20 parts by weight Polyester acrylate 20 parts by weight Ethyl acetate 30 parts by weight Isobuty acetate 10 parts by weight Benzophenone photoinitiator 0.1 parts by weight Example 4 was obtained in the same manner as Example 1 except for the above.
In the same observation as in Example 1, a so-called “red shift” could be confirmed, and authenticity could be easily confirmed.

(Comparative Example 1)
Comparative Example 1 was obtained in the same manner as Example 1, except that Mercury Pearl Pigment Color Stream Standard Model F10-01 Viola Fantasy was used as the pearl pigment.
When observed in the same manner as in Example 1, “blue shift” generally observed from red to green and blue was confirmed.
This change was common and seemed insufficient to verify authenticity.
(Evaluation test) The observation light is an ordinary white light source, and the observation object is visually observed from the vertical direction as shown in FIG. Observation. Further, as shown in FIG. 2, the light reflected from the direction inclined by 70 degrees from the vertical direction was visually observed.
(Evaluation results)
In Examples 1 to 4, a so-called “red shift” could be observed.
Compared to Example 1, in Example 2, each color was observed slightly clearly. In Example 3, the amount of red color was slight, but “red” could be confirmed with certainty, and unexpectedness was brought about. Although Example 4 had a different texture from Examples 1-3, the so-called “red shift” was sufficiently confirmed. From this, it was judged that sufficient authenticity could be confirmed.
As described above, Comparative Example 1 confirmed the “blue shift” generally observed. This color change seemed insufficient to verify authenticity.

A: Color variable ink layer showing one embodiment of the present invention 1: A pigment whose wavelength of selectively reflected light changes (pearl pigment, liquid crystal pigment, etc.)
2: Light to be observed 3: Light reflected

Claims (2)

In the color variable ink composition containing the pigment that changes the wavelength of the light that selectively reflects according to the incident angle of the light to be observed,
A pigment in which the wavelength of the selectively reflected light of the pigment shifts from a visible region of 500 nm or less to an ultraviolet region when the incident angle changes from 0 degrees to 70 degrees;
Ri Do from the pigment to shift from the infrared region to 500nm or more in the visible region,
Both the pigments, color variable ink composition aspect ratio is characterized by discoid der Rukoto 2-5. A pigment that shifts from the visible region of 500 nm or less to the ultraviolet region;
2. The color variable ink composition according to claim 1, wherein a mixing ratio of the pigment that shifts from the infrared region to a visible region of 500 nm or more is 9/1 to 5/5.

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