KR20160080748A - Security element with a color-shift effect and a method of preparing the same - Google Patents

Abstract

The present invention relates to a security element having a discoloration effect and a manufacturing method thereof and, more specifically, to a security element having a discoloration effect having a structure in which an irregular structure is formed on the surface of a substrate and a color conversion layer including an absorber layer, a space layer (or a dielectric layer), and a reflector layer is stacked on the surface of the irregular structure, and a manufacturing method thereof. In the security element according to the present invention, the surface thereof where the color conversion layer is formed assumes a color varied according to angles at which the surface is viewed, and, in particular, the presence of the irregular structure maximizes a discoloration effect, whereby the element can be applied to various products requiring security in order to ascertain the authenticity.

Description

TECHNICAL FIELD [0001] The present invention relates to a security element having a discoloring effect and a method of manufacturing the security element.

The present invention relates to a security element capable of ensuring excellent discrimination and various color conversion effects, and a method of manufacturing the same.

Recently, the rapid development of high-performance computers, scanners and color copiers has expanded the spread of sophisticated yet easy-to-use office automation devices, and expanded the knowledge base on the appearance and copying methods of security products. , ID cards, credit cards, e-passports, etc., are increasingly being exploited for crimes. Therefore, many researches are being conducted to prevent the above-mentioned problems and to prevent tampering.

Among various anti-counterfeiting technologies, the color conversion security element whose color changes according to the viewing angle has been developed in various forms because it can provide not only visual truth authenticity but also visual aesthetic sensitivity. Specifically, there are various methods such as color conversion ink printing, liquid crystal ink printing, and multilayer thin film deposition.

This color change characteristic can be controlled through the orientation of the chemical molecules used to form an appropriate design or coating structure of the optical thin film. A desired effect can be obtained by changing parameters such as the thickness of the layers to be formed and the refractive index of each layer. The change in the perceived color caused by the angle of the line of sight or the angle of the incident light is a result of combining the selective absorption effect of the material constituting the layer and the interference effect depending on the wavelength. The interference effect results from the superposition of light waves that have undergone multiple reflections, causing the perceived color to change at different angles. The position and intensity of the reflection maxima are changed due to changes in the interference effect resulting from the difference in the length of the light path in the various layers made of materials selectively strengthened at specific wavelengths as the viewing angle changes do.

The multilayer film deposition includes an absorber layer, a spacer layer (dielectric layer), and optionally a reflector layer, the order of which may be varied. Such a coating can be formed to have a symmetrical multilayer thin film structure.

The security element having such a color conversion effect can not be reproduced by merely scanning and copying, which is a fairly effective forgery prevention device. However, there is an increasing number of imitation counterfeit cases using similar films in the market, and it is difficult to cope with imitation counterfeiting only by a simple color conversion effect. Various techniques have been proposed to cope with such counterfeiting.

Korean Patent Laid-Open Publication No. 2004-0074073 proposes a security element that displays two or more different metal layers to represent different colors. In this case, the metal layer is formed on the printed ink portion and serves to additionally increase the security effect.

Korean Patent Laid-Open Publication No. 2010-0013504 discloses a photochromic thin film including a fine uneven structure on its surface. At this time, the micro concavo-convex structure promotes the photo-discoloration of the incident light, but the concavo-convex structure is formed through the nanoparticles.

These patents are intended to improve the security through the discoloration effect, but they are used as additional elements or the method of forming the concavo-convex structure is different and its effect is not sufficient.

Korean Patent Publication No. 2004-0074073 Korean Patent Publication No. 2010-0013504

As a result of various studies in order to secure superior security and discrimination, Applicant has found that when a concavo-convex structure is formed on the surface of a substrate and a color conversion layer is laminated, the color change varies with angle, And confirmed the present invention.

Accordingly, an object of the present invention is to provide a security element that can secure a good authenticity identification effect and visual attractiveness through various color conversions.

Still another object of the present invention is to provide a method of manufacturing the security element.

In order to achieve the above object, the present invention is characterized in that a color conversion layer is formed on the surface of a base material, and a concavo-convex structure is formed on the surface of the base material, And the change is different.

The concave-convex structure may be circular, triangular, ladder-like, polygonal or wavy.

The concavo-convex structure may be symmetrical or asymmetric.

The substrate having the concave-convex structure is characterized by being manufactured by a thermocompression bonding or an ultraviolet curing type embossing method.

Wherein the color conversion layer comprises an absorbing layer on at least one side of a surface in contact with the substrate; Space layer; And a reflective layer are laminated.

The security element may further include at least one layer having ultraviolet fluorescence property, infrared absorption / reflection property, or magnetic property.

According to another aspect of the present invention, there is provided a method of manufacturing a security element, comprising: preparing a substrate having a concavo-convex structure; Forming an absorbing layer over the entire surface of the substrate; Forming a space layer on the absorber layer; And forming a reflective layer on the space layer.

The security element according to the present invention not only displays various colors according to angles, but also discoloration effect can be easily observed even with a small change in viewing angle to improve discrimination.

When the security element is applied to a product, the authenticity can be easily determined. In addition, the above-described manufacturing method can be used for products requiring various security such as banknotes, ID cards, and documents.

1 is a sectional view showing an example of a security element according to the present invention.
2 is a cross-sectional view showing a concavo-convex structure according to the present invention.
3 is a cross-sectional view illustrating an effect of color change of an angle of a security element according to an embodiment of the present invention.

The present invention presents a security element with excellent visibility.

The color conversion is performed in various ways in the security element. Among them, the method of providing the observable color conversion according to the change of the angle of the incident light or the viewing angle has been developed in various forms due to its excellent authenticity identification effect. Among them, in the case of a color conversion hue or hologram through thin film interference, a multilayer structure is formed in which layers having optical interference effects are laminated on a substrate.

Accordingly, the present invention provides a security element in which a color conversion layer is formed on the surface of a base material. The base material is not flat and has a concavo-convex structure on its surface, So that the effect of color conversion depending on the angle can be maximized. In addition, the security element is introduced into the product, thereby securing an advantage of facilitating authenticity discrimination.

Hereinafter, each composition will be described in detail with reference to the accompanying drawings. The accompanying drawings are provided by way of example so that those skilled in the art can fully understand the spirit of the present invention. Therefore, the present invention is not limited to the following drawings, but may be embodied in other forms, and the following drawings may be exaggerated in order to clarify the spirit of the present invention. Also, throughout the specification, like reference numerals designate like elements.

FIG. 1 is a view illustrating a security element according to the present invention, which includes a substrate 10 and a color conversion layer 20, and the surface of the substrate is provided with a concave-convex structure.

The convexo-concave structure increases the specific surface area on the surface of the substrate, thereby improving the discoloration effect. The specific surface area can be adjusted depending on the shape, diameter, distribution, density, etc. of the concavo-convex structure. Further, due to such a concavo-convex structure, the coating property of the color conversion layer 20 to be described later is improved and additional optical characteristics can be added as the thickness is made different.

At this time, the concavo-convex structure may be any one capable of efficiently diffracting, scattering or diffusing incident light without lowering the incidence action of the incident light. The concavo-convex structures have a size of several tens of nanometers to several tens of micrometers, preferably in the range of 500 to 100,000 nm, and more preferably in the range of 600 to 50,000 nm. Further, the average interval of the irregularities is preferably 500 to 100,000 nm, more preferably 600 to 50,000 nm, and even more preferably 10,000 to 30,000 nm.

The shape of the concavo-convex structure is not particularly limited, and may be circular, triangular, ladder, polygonal, or wavy, as shown in FIGS. 2A, 2B, and 2C.

The concavo-convex structure may be symmetrical or asymmetric. In the present invention, the asymmetric shape means that irregularities of the irregularities constituting the irregular structure are irregular. Specifically, it means that the inclination angle of the surface of irregularities, the interval of irregularities, the interval between the tops of local peaks, and the like have variations.

In order to form the concavo-convex structure on the surface of the substrate 10 of the present invention, it is made from the design of the mold having the concave and convex portions. Depending on the size and shape of the concavities and convexities to be formed, such a mold may be formed by various manufacturing methods such as laser processing, electron beam processing, and lithography. For example, a glass substrate coated with a photosensitive material is exposed to a pattern having a concavo-convex structure by using a laser or an electron beam, and then subjected to development and electro-forming processes to produce a mold. Such a mold manufacturing process can use ordinary materials and methods without limitation.

The substrate 10 having the concave-convex structure of the present invention can be realized by a hot-stamping or an ultraviolet curing type embossing method.

Thermocompression is a method of applying a thermoplastic polymer by a heating method and pressing the mold at a temperature higher than the glass transition temperature and a certain pressure to form a concavo-convex structure.

In the ultraviolet curing type embossing method, unevenness can be repeatedly formed by applying an ultraviolet curing type resin by ultraviolet ray irradiation method, compressing it with a mold, and then curing it with ultraviolet rays instead of heat to produce a concave-convex structure. In addition, the ultraviolet curing type embossing method is advantageous in a process for a material which is likely to be broken at a low pressure compared to a thermocompression bonding, has no damage to thermal deformation, and is relatively easy to process in a multilayered manner.

Examples of the application method of the ultraviolet curable resin in the ultraviolet curing type embossing method include a bar coat, a dip coat, a spray coat, a roll coat, a gravure coat, a flex coat, a screen coat, a spin coat, a flow coat and an ink jet. The curing of the ultraviolet-curable resin composition may be promoted by pre-baking the coated ultraviolet-curable resin composition before curing. Examples of the heating method in the prebake include an irradiation method using an infrared heater, a circulating heating method using hot air, and a direct heating method using a hot plate. In addition, curing can be promoted by volatilizing the solvent under vacuum in the applied resin composition. Appropriate heating can be used at this time.

The substrate 10 is not limited as long as it can form a concave-convex structure on the surface of a polymer material. The substrate 10 may be selected in various ways depending on the type and type of the security product to be applied.

The material of the substrate 10 is specifically selected from the group consisting of polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate, ethylene glycol-terephthalic acid-isophthalic acid copolymer, terephthalic acid-cyclohexanedimethanol- Polyamide resins such as nylon 6, nylon 66, nylon 610 and the like, polyolefins such as polypropylene and polymethylbenzene, polyolefins such as polypropylene and polymethylbenzene, polyolefins such as polyethylene terephthalate and polyethylene naphthalate, Acrylic resins such as polyvinyl (meth) acrylate, polybutyl (meth) acrylate and methyl (meth) acrylate-butyl (meth) acrylate copolymers such as poly (Metha) acrylate means acrylate or methacrylate), polyimide, polyamideimide, polyether Polyether sulfone, polyphenylene ether, polyphenylene sulfide (PPS), polyaramid, polyether ketone, polyetheretherketone, polyetheretherketone, polyetheretherketone, polyetherketone, Engineering resins such as sulfide, styrene resins such as polystyrene, and polycarbonate resins. The material of the substrate 10 may be a copolymer resin, a mixture thereof, or a laminate composed of a plurality of layers including the resin as a main component. Of these, polyethylene terephthalate (PET), which is excellent in transparency, heat resistance, and in terms of cost, is preferable.

The thickness of the substrate 10 is not limited to a specific range, but is usually from 5 to 200 탆, preferably from 8 to 150 탆. If the thickness is less than the above range, mechanical strength is insufficient to cause warpage or loosening, and if it exceeds the above range, it may be difficult to apply to products or excessive cost may be a problem.

If necessary, the substrate 10 preprocesses the surface before depositing the color conversion layer. Concretely, an easy adhesion treatment such as a corona discharge treatment, a plasma treatment, an ozone treatment, a flame treatment, a primer (anchor coating, an adhesion promoter, a reverse adhesive) coating treatment, a preheating treatment, a dust removal treatment, May be performed. If necessary, additives such as an ultraviolet absorber, an accelerator, a plasticizer, and an antistatic agent may be added to the base material 10.

The color conversion layer 20 includes an absorbing layer 20a on at least one side of the surface contacting with the substrate 10 described above; A spacer layer 20b; And a reflection layer 20c are stacked. The multilayer thin film having such a stack structure changes color depending on the angle of the line of sight or the angle of the incident light, which is a result of combining the selective absorption effect of the material constituting the layer and the interference effect depending on the wavelength.

The absorbent layer 20a may be made of any absorbent material having the desired absorbent characteristics, including materials which absorb uniformly or non-uniformly in the visible region of the electromagnetic spectrum. Thus, an optional absorbent material or a non-selective absorbent material can be used depending on the desired color conversion characteristics. For example, the absorbent layer may be formed of a non-selective absorbent metal material that is at least partially vapor-deposited or semi-opaque.

The material that can be used for the absorbent layer 20a is one selected from the group consisting of Cr, Al, Cu, Co, Ni, Zn, Sn, Ag, Pd, Pt, Ti, Va, Fe, W, Mo, Rh, Nb, Can be selected and used. Among them, Cr is preferable when the absorption effect and the adhesion with the other metal layer are considered.

The thickness of the absorbing layer 20a may have a thickness ranging from 1 to 50 nm, preferably from 3 to 15 nm, depending on the desired discoloration effect. This absorbent layer 20a may be formed of a single material, may have various combinations and arrangements of materials, and may have the same or different physical layer thicknesses.

The spacer layer 20b acts as a spacer in the stack structure described above. This layer is formed to have an interference color and an optical thickness effective to impart desired color conversion characteristics. Thus, the space layer 20b may be selectively transparent or may be selectively absorbent so as to contribute to the coloring effect of the pigment.

The material used for the space layer 20b is not particularly limited and may be variously selected from materials known in the art depending on the purpose. A material used for the spacer layer (20b) of the invention can be used for one type of compound selected from the group consisting of _{SiO 2, SiN, Al 2 O} 3, TiO 2, ZrO 2, MgF 2 , or a combination thereof. Preferably, SiO ₂ and Al ₂ O ₃ are usable.

The thickness of the spacer layer 20b varies depending on the desired color conversion effect but typically ranges from 100 to 800 nm. In addition, such a space layer 20b may be formed of a single material, may have various combinations and arrangements of materials, and may have the same or different physical layer thicknesses.

The reflective layer 20c may be composed of various reflective materials. Preferably, a metal, a metal alloy, or a combination thereof may be used because such materials have high reflectivity and are easy to use. For example, one selected from the group consisting of Al, Sn, Cu, Zn, Pt, Au, Ag, Cr, Ti, Mo, Fe, Pd, Ni and Co or a combination thereof can be used. Among them, Al is preferable when considering the reflection effect, uniformity of thickness, thinning, and the like.

The reflective layer 20c may be made of the same material or may be made of different materials. In addition, it may be formed as a single layer or multiple layers and may have the same or different physical layer thicknesses.

The thickness of the reflective layer 20c is in the range of 1 to 200 nm, preferably in the range of 10 to 100 nm. If it is less than the above range, a sufficient reflection effect can not be ensured. On the contrary, if the above range is exceeded, the coating film quality is deteriorated and a problem that color conversion effect can not be obtained arises.

In addition, the reflective layer 20c may be patterned by a demetalation technique. Various methods such as wet or dry methods can be used for patterning in the demetallization technique. Further, when a fluorescent ink is applied below the demetallized region, the fluorescence can be observed at the demarcated region upon ultraviolet irradiation. In addition, one or more layers having ultraviolet fluorescence property, infrared absorption / reflection property, or magnetic property may be further included. For example, an ink having an absorption or reflection characteristic in response to infrared rays may be used, or a magnetic ink may be further applied as a device sensing element by further applying a magnetic property using a character, a specific pattern, or a change in ink thickness.

In order to apply the security element to the security product, an adhesive layer and a protective layer are additionally stacked, which can be operated according to a conventional technique in the related field.

The security element according to the present invention comprises: preparing a substrate having a concavo-convex structure; Forming an absorbing layer over the entire surface of the substrate; Forming a space layer on the absorber layer; And forming a reflective layer on the spacer layer.

Specifically, the method of forming the concavo-convex structure on the surface of the base material in the step of preparing the substrate having the concavo-convex structure is as described above.

Next, in the step of forming the absorption layer, the space layer and the reflection layer over the surface of the substrate, the deposition of each layer is performed by a vacuum deposition method.

As the vacuum deposition method, a conventionally known method is used. Specifically, there are CVD (chemical vapor deposition) using a chemical method and physical vapor deposition (PVD) using a physical method in a vacuum deposition method. CVD includes MOCVD (Metal-Organic Chemical Vapor Deposition) and HVPE (Hydride Vapor Phase Epitaxy). PVD includes thermal evaporation, E-Beam deposition, laser deposition, sputtering, and ion plating.

CVD using a chemical method is a method in which a substance to be deposited on a substrate is injected as a gas in a gaseous state rather than a solid state, and is deposited on the substrate in a reaction chamber through high temperature decomposition or high temperature chemical reaction. This method is excellent in adhesion and can be uniformly deposited on a complex substrate, and deposition of a high purity substance is easy. In addition, localized deposition can be performed by selecting a desired region on a substrate of a specific type. However, since a high temperature of 500 ° C or more is required for a smooth reaction, there may be a problem in the physical properties of the substrate and the metal. Plasma Enhanced CVD (PECVD), which has been recently put to practical use, can be deposited at a relatively low temperature and is available for the present technology.

The evaporation method of the evaporation material includes resistance heating, electron beam heating, ion beam heating, laser heating, and high frequency induction heating, and resistance heating and electron beam heating Is mainly used. Vacuum deposition is the most excellent method in terms of high-speed film formation, but it has a problem that adhesion is too low.

Sputtering is a technique of depositing a thin film on the surface of a substrate by bombarding a metal plate with an inert element such as argon and causing metal molecules to protrude therefrom. Sputtering is superior to other vacuum evaporation techniques in terms of adhesion to a thin film, but there is a problem in forming a high-speed film by a technique of the lowest deposition rate.

Ion plating is a method in which a gas such as argon is injected into a vacuum chamber to cause a plasma in a vacuum state to ionize a deposition material and a gas to deposit the material to be deposited with a high energy. Since the evaporated particles are deposited with high energy, the deposition rate is high and adhesion is good. In general, a film formed by ion plating has an adhesion of 50 to 100 times higher than that of conventional vacuum deposition or wet plating, and a uniform compound film can be easily obtained due to the activation effect by discharge.

In the present invention, the present invention can be selectively applied in consideration of the kind of material constituting each layer, the adhesion to the substrate and adjacent layers, the convenience of work process, and the uniformity of quality of each layer.

The above-mentioned security factors are applied to the identity information of the banknotes, securities, and passports, and the visa fields, special documents, cards, and various identification cards. In this case, it is possible to provide a security element which is visually distinguished from the conventional one. Also, the colors observed on the left, right, and front and back are different depending on the pattern formed on the surface.

By using these characteristics, it is possible to easily determine the authenticity of imitation forgery. The color conversion security film produced in this way is excellent in security and discrimination, and can contribute to prevention of illegal or alteration of various security products (banknotes, passports, identification cards, etc.).

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention. Such variations and modifications are intended to be within the scope of the appended claims. In the following, "%" and "part" representing the content are on a mass basis unless otherwise specified.

Example 1 and Comparative Examples 1 and 2: Fabrication of security elements

[Example 1]

A polyethylene terephthalate (PET) film having a thickness of 15 탆 and a width of 320 ㎜ was used as a film substrate, and an uneven mold having a triangular cross-sectional shape was produced. The size of the triangle was selected as 20 ㎛ in base and 8 ㎛ in height. The formed irregularities were designed to form a bone and an acid in the longitudinal direction of the film, and the whole shape was made of a Taiheiyo pattern.

Subsequently, the unevenness formation on the film substrate was carried out using an ultraviolet curing type embossing. An ultraviolet curable resin was applied on the substrate, pressed with an uneven mold roll, and cured with ultraviolet rays to form unevenness.

The multilayer thin film coating of the unevenly formed film was formed by a vacuum deposition method. The absorber layer was laminated with chromium to a thickness of 5 nm and the space layer was deposited with silicon dioxide. The triangular pattern was formed so that one side of the triangular pattern was 360 nm and the other side thereof was 290 nm. And the reflective layer was deposited with aluminum to a thickness of 40 nm. The generated security factor is shown in FIG.

[Comparative Example 1]

An absorbing layer of 5 nm, a space layer of 360 nm, and a reflective layer of 40 nm were deposited in the same manner as in Example 1 except that the concavo-convex structure was formed.

[Comparative Example 2]

Except that the concavo-convex structure was formed on the base material in Example 1, a 5 nm thick absorber layer, a 290 nm space layer, and a 40 nm thick reflective layer were deposited in the same manner.

Experimental Example 1

The color conversion effect of the film obtained through the above Examples and Comparative Examples shows different colors depending on the angle. In the case of Example 1, as shown in Fig. 3, it was confirmed that the colors were different from each other in the direction of the arrows. Specifically, the film was observed to be bright yellow purple on the front face. At this time, the left side of the triangle has a lot of left side. When the view is tilted, the color rapidly changes to blue, and when it tilts more, it turns purple. When we tilted the right side of the right side of the triangle, the color suddenly changed from light purple to yellowish green, and when it tilted further, it turned blue. As a result, it was confirmed that the observed color varies depending on the thickness of the space layer. And when tilted back and forth of the triangle, it was observed that it changed from bright southern purple to light green. In the case of Comparative Example 1, the color change from blue to purple was observed when the film was tilted at the angle of view from the front. In the case of Comparative Example 2, the color change from yellow to green was observed. However, it was not confirmed in Comparative Examples 1 and 2 that the abrupt color change and the right and left color changes in different colors when the left and right sides of the triangular pattern are observed as in Example 1, respectively.

The security element according to the present invention is visually distinguishable and can be used as a security element for cards such as banknotes, checks, gift certificates, credit cards, ID cards, and passports. In addition, the discoloration effect can cause visual interest and can be introduced into brand labels or products to provide aesthetics and distinctiveness.

10: substrate 20: color conversion layer
20a: absorption layer 20b: space layer
20c:

Claims (11)

A security element having a color conversion layer formed on a surface of a substrate,
Characterized in that a concavo-convex structure is formed on the surface of the substrate,
Wherein the color change of one side surface and the other side surface are different depending on the shape of the concavo-convex structure. The security element according to claim 1, wherein the concave-convex structure is circular, triangular, ladder-like, polygonal or wavy. The security element according to claim 1, wherein the concave-convex structure is symmetrical or asymmetrical. The security element according to claim 1, wherein the substrate having the uneven structure is manufactured by thermo compression bonding or ultraviolet curing type embossing. The security element of claim 1, wherein the substrate comprises a polymeric material. The color conversion layer according to claim 1, wherein the color conversion layer comprises an absorbing layer on at least one side of a surface in contact with the substrate; Space layer; And a reflective layer. 7. The method of claim 6, wherein the absorbent layer is selected from the group consisting of Cr, Al, Cu, Co, Ni, Zn, Sn, Ag, Pd, Pt, Ti, Va, Fe, W, Mo, Rh, And a selected one of the security elements. The method of claim 6, wherein the spacer layer is a security element, characterized in that it comprises one kind selected from the group consisting of _{SiO 2, SiN, Al 2 O} 3, TiO 2, ZrO 2, MgF 2 , or a combination thereof. The reflective layer according to claim 6, wherein the reflective layer comprises one selected from the group consisting of Al, Sn, Cu, Zn, Pt, Au, Ag, Cr, Ti, Mo, Fe, Pd, Ni, Co, Wherein the security element is a security element. The security element of claim 1, wherein the security element further comprises one or more layers having ultraviolet fluorescence properties, infrared absorption / reflection properties, or magnetic properties. Preparing a substrate having a concavo-convex structure formed thereon;
Forming an absorbing layer over the entire surface of the substrate;
Forming a space layer on the absorber layer; And
And forming a reflective layer on the spacer layer.

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