KR102002500B1 - Photonic crystal film for security feature, and method of manufacturing the same, and anti-counterfeiting product using the same - Google Patents

Abstract

The present invention relates to a photonic crystal film for a security element, a method for manufacturing the same, and an anti-falsification article including the same, and more particularly, to a photocatalyst film for a security element comprising a polyurethane based polymer matrix; And a colloid particle dispersed in the polyurethane based polymer matrix and arranged in a crystal lattice structure. The photonic crystal film for a security element has a high reflectance characteristic and is excellent in visibility, It can be improved and collapsible.

Description

TECHNICAL FIELD [0001] The present invention relates to a photonic crystal film for a security element, a manufacturing method thereof, and an anti-falsification article including the photonic crystal film for security element,

The present invention relates to a photonic crystal film for a security element, a method of manufacturing the same and an anti-falsification article including the same. More particularly, the present invention relates to a photonic crystal film for a security element, And an anti-falsification article comprising the same.

A photonic crystal is a material that forms a crystal lattice by regularly arranging particles having different refractive indices from a matrix, and refers to a material having a photonic band gap by changing the dielectric constant periodically at a half wavelength of light.

The photonic bandgap controls a photon in a photonic crystal in the same manner as the electron bandgap controls electrons in a semiconductor. When light having a broad spectrum from the outside is incident on the photonic crystal, the wavelength band corresponding to the photonic bandgap Light is selectively propagated without propagating into the material. When such a photonic band gap exists in the visible light region, the selective reflection due to the photonic band gap appears as a reflection color.

The regular arrangement of the colloid particles is the color corresponding to the photonic bandgap of the photonic crystal, which is represented by the same principle as that of the reflection color. The color of the colloidal photonic crystal is determined by the refractive index of the colloidal and matrix materials, the crystal structure, the size of the particles, the spacing between the particles, and so on. Therefore, by controlling this, a photonic crystal having a desired reflection color can be manufactured.

On the other hand, a photonic crystal in the form of a film can increase the reflectance by increasing the thickness of the film to give a reflection color excellent in visibility. However, since the mechanical strength of the photonic crystal film itself is very weak, There is a limit to apply to areas such as banknotes and security documents that require flexibility.

Therefore, it is necessary to develop a photocrystalline film having a high reflectance characteristic and excellent visibility and flexibility, which is foldable.

A similar precedent document is disclosed in Korean Patent Publication No. 10-2015-0031862.

Korean Patent Publication No. 10-2015-0031862 (Feb.

An object of the present invention is to provide a photonic crystal film for a security element which has high reflectance characteristics and is excellent in visibility and flexibility and can be folded.

Another object of the present invention is to provide a method for manufacturing a photonic crystal film for a security element, which has high reflectance characteristics and is excellent in visibility and flexibility and can be folded.

Another object of the present invention is to provide an anti-fake article comprising a photonic crystal film for a security element which has a high reflectance characteristic and is excellent in visibility and flexibility and can be folded.

One aspect of the present invention for achieving the above object is a polyurethane-based polymer matrix; And a colloidal particle dispersed in the polyurethane-based polymer matrix and arranged in a crystal lattice structure.

In one embodiment, the photonic crystal film for the security element may have a maximum reflectance of 10% or more.

In one embodiment, the photonic crystal film for the security element may have a thickness of 10 to 200 탆.

In the above embodiment, the polyurethane based polymer matrix may be prepared from a polyurethane based prepolymer.

In this embodiment, the polyurethane-based prepolymer may have a viscosity of 100 to 1000 cps at 80 캜.

In this embodiment, the polyurethane-based prepolymer may have a weight average molecular weight of 500 to 30,000 g / mol.

In one embodiment of the present invention, the refractive index difference between the polyurethane based polymer matrix and the colloidal particles may be 0.02 or more.

In one embodiment, the refractive index of the polyurethane based polymer matrix is 1.4 to 1.5, and the refractive index of the colloidal particles may be 1.3 to 2.95.

In this embodiment, the average particle diameter of the colloidal particles may be 50 to 315 nm.

In the above embodiment, the colloidal particles may satisfy the following relational expression (1).

[Relation 1]

Da x 0.95? Ds? Da x 1.05

(In the above relational expression 1, Ds is the particle diameter (nm) of the colloidal particles and Da is the average particle diameter (nm) of the colloidal particles.)

In one embodiment, the colloidal particles may be selected from metal nanoparticles, metal oxide nanoparticles, organic nanoparticles, and carbon nanoparticles.

Another aspect of the invention relates to an anti-fake article comprising a photonic crystal film for the security element of each of the above aspects.

Another aspect of the present invention relates to a photonic crystal film for a security element comprising a polyurethane-based prepolymer, a colloid particle and a photoinitiator, the dispersion being applied on a substrate or injected between two parallel transparent plates and irradiated with light And a method for producing the same.

In the above embodiment, the dispersion may be applied on the substrate at a temperature of 60 to 100 DEG C or may be injected between the two transparent plates.

A photonic crystal film for a security element according to the present invention comprises a polyurethane based polymer matrix; And the colloidal particles dispersed in the polyurethane based polymer matrix and arranged in a crystal lattice structure can improve the flexibility of the photonic crystal film for the security element and the adhesion between the polyurethane based polymer and the colloid particles is excellent, As shown in FIG. It is possible to prevent film damage such as breakage or peeling easily, thereby improving the durability of the film and facilitating handling of the film, so that it can be applied as a security element to anti-counterfeit articles such as bank notes and security documents requiring flexibility There are advantages.

FIG. 1 is a reflectance (%) measurement data of a photonic crystal film for a security element manufactured according to Example 1 and Comparative Example 1. FIG.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a photonic crystal film for a security element according to the present invention, a method of manufacturing the same, and an anti-fake article including the same will be described in detail with reference to the accompanying drawings. The following 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.

Hereinafter, the technical and scientific terms used herein will be understood by those skilled in the art without departing from the scope of the present invention. Descriptions of known functions and configurations that may be unnecessarily blurred are omitted.

Conventionally proposed photonic crystal films for security elements use photocurable polymers of ETPTA (ethoxylated trimethylolprpane triacrylate) as a matrix. In such a case, the photonic crystal film has excellent reflectance and little flexibility, but when the physical deformation such as folding or grinding is applied, the film is easily broken or damaged, which has limitations in practical application as a security element.

Accordingly, the present inventors intend to propose a photonic crystal film for a security element which is not easily damaged by a high degree of physical deformation.

In detail, a photonic crystal film for a security element according to an exemplary embodiment of the present invention has a reflection spectrum with respect to a specific wavelength, and includes a polyurethane based polymer matrix; And colloidal particles dispersed in the polyurethane based polymer matrix and arranged in a crystal lattice structure.

As described above, the flexibility of the photonic crystal film for the security element can be improved by using the polyurethane polymer as the matrix, and the adhesion between the polyurethane polymer and the colloid particles is excellent, so that the colloid particles may not be easily separated from the matrix. It is possible to prevent film damage such as breakage or peeling easily, thereby improving the durability of the film and facilitating handling of the film, so that it can be applied as a security element to anti-counterfeit articles such as bank notes and security documents requiring flexibility There are advantages.

Specifically, the photonic crystal film for a security element according to an exemplary embodiment of the present invention can have extremely excellent flexibility, and even when a highly physical deformation such as a fold is applied, the film is not easily broken or damaged, ) Material is practically possible.

In addition, with such excellent flexibility, the photonic crystal film for a security element is kept intact in a circumstance where a high degree of physical deformation is repeatedly applied, so that the photonic crystal film for a security element has excellent reflectance characteristics It can be maintained continuously, and it can not lose its property as a security element.

In one example of the present invention, the photonic crystal film for a security element is not necessarily limited to this, but the maximum reflectance may be 10% or more, more preferably 20% or more, and preferably 40% or more. By having such excellent reflectance characteristics, it is possible to have excellent visibility and discrimination, and even when compared with a conventional photonic crystal film having excellent reflectance, it exhibits a reflectance that does not deteriorate at all. Particularly preferably, the maximum reflectance of the photonic crystal film for the security element may be 48% or more. The upper limit of the maximum reflectance is not particularly limited, but the upper limit of the practical maximum reflectance may be 60% or less. In this case, the wavelength region where the maximum reflectance appears may vary depending on the size of the colloidal particles used, and it is needless to say that the wavelength region can not be limited. Specifically, for example, when spherical silica having an average particle diameter of 170 nm is used as colloidal particles, the maximum reflectance may appear in a wavelength range of 530 to 535 nm, and the reflection color may be a green color series. Or when spherical silica having an average particle diameter of 200 nm is used as colloidal particles, the maximum reflectance may appear in a wavelength range of 620 to 630 nm, and the reflection color may be a red color series.

For example, the photonic crystal film for a security element may have a thickness of 10 to 200 nm. The thickness of the photonic crystal film for a security element may be in the range of 10 to 200 nm, Lt; / RTI > In this range, the photonic crystal film for the security element has a remarkably excellent flexibility, but the proper mechanical strength is maintained, so that the photonic crystal film for the security element can be maintained in its original shape without being damaged even in the environment where high physical deformation is repeatedly applied. More preferably, the thickness of the photonic crystal film for the security element may be between 30 and 150 microns, and more preferably between 50 and 100 microns.

On the other hand, in order for the photonic crystal film for security element to have excellent properties as described above, it is preferable to appropriately select the polymer matrix and the colloidal particles.

In one example of the present invention, the polyurethane-based polymer matrix may be one prepared from a polyurethane-based prepolymer. In order to secure flexibility to a degree that can be folded and to improve adhesion with colloidal particles, From the viewpoint of preventing damage, it is very important to appropriately select the polyurethane based prepolymer. Here, the polyurethane-based prepolymer may be a polyurethane-based polymer having a relatively low degree of polymerization, which contains a curable functional group, and is a polyurethane-based polymer matrix.

Preferably, the polyurethane based prepolymer according to one example of the present invention may have an appropriate viscosity range at an appropriate temperature. From this, it is possible to manufacture a photonic crystal film for a security element having a very thin thickness, and a polyurethane polymer matrix having excellent self-flexibility can be formed, thereby preventing the photonic crystal film for security element from being easily broken or damaged. In addition, when a photonic crystal film for a security element is manufactured, as described later, the dispersion can be easily injected between two transparent flat plates, thereby shortening the film manufacturing process time.

As a specific example, the polyurethane-based prepolymer may have a viscosity at 80 ° C of from 100 to 1,000 cps, more preferably from 200 to 800 cps, and still more preferably from 300 to 600 cps. On the other hand, when the viscosity of the polyurethane based prepolymer is more than 1,000 cps at 80 캜, the fluidity of the dispersion may be insufficient, so that injection into the two transparent flat plates may be difficult, thereby making it difficult to produce a film-like photonic crystal.

In addition, the preferred weight average molecular weight of the polyurethane based prepolymer according to an exemplary embodiment of the present invention may be 500 to 30,000 g / mol. It is possible to easily form a polyurethane based polymer matrix having excellent flexibility in the above range. More preferably, the weight average molecular weight of the polyurethane based prepolymer may be 800 to 10,000 g / mol, and more preferably the weight average molecular weight of the polyurethane based prepolymer may be 1,000 to 5,000 g / mol.

More specifically, the polyurethane-based prepolymer according to an example of the present invention may contain at least one photocurable functional group, and the photocurable functional group is not particularly limited as long as it is a polymerizable group capable of being polymerized through light irradiation, For example, an ethylenic unsaturated group such as a vinyl group, an acrylate group or a methacrylate group.

As a more specific example, the polyurethane-based prepolymer may be produced by polymerization reaction of a polyisocyanate-based compound and a polyol-based compound in a range that does not impair physical properties such as flexibility, refractive index and reflectance, .

In one example of the present invention, the polyisocyanate compound may be one or two or more selected from aromatic polyisocyanates, aliphatic polyisocyanates and alicyclic polyisocyanates, and more specifically, for example, aromatic polyisocyanates include 1,3- Tolylene diisocyanate (TDI), 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate (MDI), 2,4-di Phenylmethane diisocyanate, 4,4'-diisocyanatobiphenyl, 3,3'-dimethyl-4,4'-diisocyanatobiphenyl, 3,3'-dimethyl-4,4'-diisocyanatodi Naphthylene diisocyanate, 4,4 ', 4 "-triphenylmethane triisocyanate, m-isocyanatophenylsulfonyl isocyanate, or p-isocyanatophenylsulfonyl isocyanate, and the aliphatic pole The isocyanate may be selected from the group consisting of ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), dodecamethylene diisocyanate, 1,6,11-undecane triisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, Diisocyanatomethyl caproate, bis (2-isocyanatoethyl) fumarate, bis (2-isocyanatoethyl) carbonate or 2-isocyanatoethyl-2,6-di Cyclohexane diisocyanate, cyclohexane diisocyanate, cyclohexane diisocyanate, cyclohexane diisocyanate, cyclohexane diisocyanate, cyclohexane diisocyanate, cyclohexane diisocyanate, and cyclohexylene diisocyanate. The cycloaliphatic polyisocyanate may be isophorone diisocyanate (IPDI), 4,4'-dicyclohexylmethane diisocyanate Isocyanate (hydrogenated TDI), bis (2-isocyanatoethyl) -4-dicyclohexene-1,2-dicarboxylate, 2,5-norbornane diisocyanate or 2,6- Boranediisocyanate, and the like, but are not particularly limited thereto.

In one example of the present invention, the polyol compound may be a polyester polyol, a polyether polyol, or a mixture thereof. More specifically, for example, the polyester polyol may be polyethylene adipate, polybutylene adipate, Poly (ethylene oxide adipate), poly (ethylene glycol), poly (ethylene glycol), poly (ethylene glycol) But is not limited thereto.

On the other hand, the colloidal particles are dispersed in a matrix to form a crystal lattice structure, and thus the photonic crystal film for a security element can have a photonic crystal characteristic. The material satisfies a specific size and is not particularly limited as long as it is commonly used in the art It can be used without. Specifically, for example, the colloidal particles may be any one or two or more selected from metal nanoparticles, metal oxide nanoparticles, organic nanoparticles, and carbon structure nanoparticles. More specifically, the metal nanoparticles may be at least one selected from the group consisting of Au, Ag, Cu, Ni, Zn, Al, Sn, Pd, Pt, and silicon (Si), or a mixture thereof, or an alloy thereof, and the metal oxide nanoparticles may be oxides of the metal nanoparticles. The organic nanoparticles may be any one or more selected from the group consisting of polyethylene, polypropylene, polyacrylate, polymethyl methacrylate, polystyrene, polydimethylsiloxane, polyimide, polyethylene terephthalate, polyethylene naphthalate, polyether sulfone, and polycarbonate Polymer nanoparticles, and the carbon structure nanoparticles may be graphite or the like.

In one example of the present invention, the colloid particles may be used without particular limitation as long as they have a size commonly used in the art. Specifically, the average particle size of the colloid particles may be 50 to 315 nm. More specifically, the size of the colloidal particles can be controlled differently depending on the volume occupied by the colloidal particles in the photonic crystal film. That is, the size of the colloid particles used may vary depending on the volume ratio of the colloid particles. When the volume of the colloid particles is 5 to 25% by volume based on the total volume of the crystal film, 180 nm, and when the volume of the colloidal particles is more than 25 to 60% by volume, the average particle size of the colloidal particles may be more than 180 nm to 250 nm, and when the volume of the colloidal particles is more than 60% The average particle size of the colloidal particles may be from 250 nm to 315 nm, but is not limited thereto. As a more specific example, when the volume of the colloidal particles is 33 vol%, the average particle size of the colloidal particles may be 140 to 220 nm based on the total volume of the photonic crystal film. When the volume is 5 vol% The average particle diameter may be 50 to 120 nm, and when the volume is 90 volume%, the average particle diameter of the colloidal particles may be 180 to 315 nm. If it is out of the above range, it may be difficult to secure visibility of the photonic crystal film for the security element beyond the reflection wavelength of the visible light region. At this time, the shape of the colloidal particles is not particularly limited, but it may be preferable to use spherical nanoparticles.

Particularly, from the viewpoint of obtaining an excellent reflectance by forming a crystal lattice regularly arranged in a polyurethane based polymer matrix, the colloidal particles may satisfy the following relational expression (1).

[Relation 1]

Da x 0.95? Ds? Da x 1.05

(In the above relational expression 1, Ds is the particle diameter (nm) of the colloidal particles and Da is the average particle diameter (nm) of the colloidal particles.)

That is, when the average particle size of the colloidal particles is 200 nm, the particle size of each of the colloidal particles may satisfy the particle size of 190 to 210 nm. In this case, the particle size and the average particle size (D50) of the colloidal particles may be calculated from a particle size distribution, and the particle size distribution may be measured using a laser particle size analyzer.

Thus, by using colloidal particles having extremely uniform particle diameters, the crystal lattice structure can be achieved with high precision and regularity. Thus, the photonic crystal film for security element has excellent reflectivity and excellent visibility.

In addition, the photonic crystal is a material that forms a crystal lattice by regularly arranging the particles having different refractive indexes from the matrix. In addition, the refractive index of the polyurethane polymer and the refractive index of the colloidal particles are very important.

In one preferred embodiment, the refractive index difference between the polyurethane-based polymer matrix and the colloid particles may vary depending on the material used. In one embodiment, the refractive index difference between the polyurethane-based polymer matrix and the colloid particles may be 0.02 or more, 0.03 to 1.55. In this range, the photonic crystal film for a security element can have an excellent reflection spectrum for a specific wavelength, and more specifically, it can have a maximum reflectance of 10% or more, preferably 40% or more.

At this time, the refractive index of the polyurethane based polymer matrix may be 1.4 to 1.5, and the refractive index of the colloidal particles may be 1.3 to 2.95. More specifically, and as a non-limiting example, the refractive index of the polymer matrix may be from 1.45 to 1.49, preferably from 1.47 to 1.49, and the refractive index of the colloidal particles may vary depending on the type of colloidal particles, When the colloidal particles are silica nanoparticles, the refractive index of the silica nanoparticles may be 1.43 to 1.5, more specifically 1.45.

Meanwhile, such a photonic crystal film for a security element can be used without any particular limitation as long as it is a known method for producing a film. For example, the photonic crystal film can be manufactured by the following method.

In detail, a method of manufacturing a photonic crystal film for a security element may include applying a dispersion containing a polyurethane-based prepolymer, colloid particles and a photoinitiator onto a substrate, or injecting and irradiating light between two parallel transparent plates have.

That is, a dispersion is applied on a substrate, and then photocured to prepare a photonic crystal film. Alternatively, a dispersion liquid is injected between two transparent flat plates having a gap equal to the thickness of a desired film, A photonic crystal film for a security element can be manufactured. It is preferable to prepare a photocurable film by injecting a dispersion liquid between two transparent flat plates, which can easily adjust the thickness of the film and may be preferable in terms of producing a film having a very uniform thickness.

In the dispersion according to an example of the present invention, the volume fraction of the polyurethane-based prepolymer: colloidal particles is not particularly limited, but may be 0.9: 0.1 to 0.5: 0.5. In such a range, the colloidal particles can be arranged in a crystal lattice structure due to the action of the repulsive force between the colloidal particles, and a specific reflection spectrum can be obtained, so that the visibility and the discrimination can be excellent. In order to more effectively arrange the colloidal particles in a crystal lattice structure, the volume fraction of the polyurethane-based prepolymer: colloidal particles may be more preferably from 0.8: 0.2 to 0.6: 0.4. The photoinitiator is not particularly limited as long as the polyurethane-based prepolymer can sufficiently cure it. For example, the photoinitiator may be added in an amount of 0.3 to 3 wt% based on the volume of the polyurethane-based prepolymer, more preferably 0.5 to 2 wt% It may be preferable that the reflectance of the photonic crystal film for the security element does not decrease.

In this case, the polyurethane-based prepolymer and the colloid particles are the same as those described above, and a duplicate explanation thereof is omitted. The photoinitiator is not particularly limited as long as it is ordinarily used in the art, and specifically, for example, 1- Methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane-1-one, benzyldimethylketone, 1- (4-dodecylphenyl) -2 2-methylpropane-1-one, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropane 1-one, benzophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy- , 4,4'-diethylaminobenzophenone, dichlorobenzophenone, 2-methyl anthraquinone, 2-ethyl anthraquinone, 2-methyl thioxanthone, 2-ethyl thioxanthone, 2,4- And 2,4-diethylthioxanthone. It may be more than one or two.

Once the dispersion is ready, it can be applied on a substrate or injected between two transparent plates. The coating method is not particularly limited as long as it is commonly used, and can be used without any particular limitation, and can be applied by various methods such as spin coating, doctor blading, dip coating, spray coating, casting, screen printing, inkjet printing, electrostatic hydraulic printing, microcontact printing, Printing, reverse offset printing, gravure offset printing, or the like. In addition, the injection method is also not particularly limited, and for example, the capillary force can fill the dispersion between two transparent plates.

At this time, the dispersion may be applied on the substrate at a temperature of 60 to 100 DEG C, or may be injected between the two transparent plates, in which the polyurethane-based prepolymer has an appropriate viscosity, And it can be easily injected between two transparent flat plates to shorten the manufacturing process time.

At this time, the substrate is not particularly limited as long as it can easily separate the photonic crystal film. For example, it may be a glass plate or the like.

On the other hand, the interval between the two transparent plates can be adjusted according to the desired thickness of the film, and can be, for example, 30 to 150 μm, more preferably 50 to 100 μm.

In addition, it is preferable that the transparent plate is selected so that the polyurethane-based prepolymer can be well-light-cured through light transmission and well separated from the photonic crystal film for the security element. Specifically, for example, a glass plate can be used, no.

After the coating or injection of the dispersion, light is irradiated to cause the polyurethane-based prepolymer to be photopolymerized to form a polyurethane-based polymer matrix; And a colloid particle dispersed in a polyurethane-based polymer matrix and arranged in a crystal lattice structure.

In this case, the light may be ultraviolet light, more specifically, light having a wavelength range of 200 to 500 nm, more preferably, light having a wavelength range of 254 to 400 nm, more preferably 330 to 370 nm But the present invention is not limited thereto, and it may be a mixed light of a plurality of wavelengths or a light of a single wavelength.

In one example of the present invention, the light irradiation can be controlled in different conditions depending on the size of the photonic crystal film for the security element and the like, and the light can be irradiated until the dispersion containing the polyurethane based prepolymer is sufficiently cured Of course. In one nonlimiting embodiment, the light irradiation may be performed by irradiating light with an output of 5 to 20 mW / cm 2 for 3 to 30 seconds, more preferably with an output of 7 to 15 mW / cm 2 for 5 to 10 seconds However, the present invention is not limited thereto.

It is needless to say that a process for separating the photonic crystal film for the security element manufactured between the substrate or the transparent plate and then removing the uncured unreacted material may be additionally performed.

The present invention also provides an anti-falsification article comprising the photonic crystal film for a security element described above.

More specifically, the anti-counterfeit article is an article to be protected against forgery; And a photonic crystal film for a security element formed on one side of the object article. That is, the anti-counterfeit article may have a structure in which a target article and a photonic crystal film for a security element are laminated, and it is possible to attach a photonic crystal film for a security element to one side of a target article through a known lamination method, . At this time, a polymer adhesive may be used to increase the adhesion between the target article and the photonic crystal film for a security element. The polymer adhesive is not particularly limited, but may be specifically polyester, nylon, polyimide, polysiloxane or polypropylene.

In the example of the present invention, the object article is not particularly limited as long as it is required to prevent forgery, and it may be a banknote, a securities, an official document, a certificate, an identification card or a financial card, and the photonic crystal film for security element, The same bar redundancy description is omitted.

Hereinafter, a photonic crystal film for a security element according to the present invention, a method of manufacturing the same, and an anti-fake article including the same will be described in detail with reference to the following examples. It should be understood, however, that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention. Unless otherwise defined, all technical and scientific terms have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Also, the singular forms as used in the specification and the appended claims are intended to include the plural forms as well, unless the context clearly indicates otherwise. In addition, the unit of the additives not specifically described in the specification may be% by weight.

[Example 1]

The dispersion was injected between two glass plates having a separation distance of 50 占 퐉 at 80 占 폚 and irradiated with light (wavelength 365 nm, output 12 mW / cm2) for 7 seconds to cure the dispersion, and then the two glass plates were removed To prepare a photonic crystal film for a security element.

The dispersion was a mixture of silica nanoparticles having an average particle diameter of 200 nm and silica nanoparticles having an average particle diameter of 200 nm and a silica nanoparticle having a mean particle diameter of 200 nm and a urethane acrylate (Miramer PU2100, a viscosity of 6,700 cps at 25 캜, a viscosity of 400 cps at 80 캜, Hydroxy-2-methyl-1-phenyl-1-propanone (Darocur 1173), the volume fraction of the urethane acrylate: silica nanoparticles was 67: 33 and the photoinitiator Darocur 1173 was urethane acrylate By weight to 1% by weight. At this time, the viscosity of the dispersion at 80 DEG C was 1000 cps.

[Example 2]

All processes except that urethane acrylate (Miwon Specialty Chemical, Miramer PU5000) having a weight average molecular weight of 1,800 g / mol, a viscosity of 1,800 cps at 25 캜 and a viscosity of about 10 cps at 80 캜 were used in the same manner as in Example 1 . At this time, the viscosity of the dispersion at 80 DEG C was about 30 cps.

[Example 3]

Except that urethane acrylate methacrylate (Sigma-aldrich, MAU) having a weight average molecular weight of 803 g / mol, a viscosity of 3,000 cps at 25 DEG C and a viscosity of about 10 cps at 80 DEG C was used in Example 1 . At this time, the viscosity of the dispersion at 80 DEG C was about 30 cps.

[Comparative Example 1]

Except that ETPTA (weight average molecular weight: 428 g / mol) was used as the prepolymer.

[Characteristic evaluation]

The reflectance in the wavelength range of 400 to 800 nm was measured using the films prepared from Examples 1 to 3 and Comparative Example 1, and the results of Example 1 and Comparative Example 1 are shown in FIG.

As a result, it was found that the films prepared from Examples 1 and 2 had excellent reflectance by measuring the maximum reflectance at about 50%, which is almost similar to that of the conventional photonic crystal film of Comparative Example 1, It was confirmed that the application is possible. However, it was confirmed that the film produced from Example 3 had no reflection color and was difficult to apply for a security element.

The films produced in Examples 1 to 3 and Comparative Example 1 were subjected to a flexing test, and as a result, the films prepared in Examples 1 and 3 exhibited very good flexibility so as to be collapsible. However, the films prepared in Example 2 Showed a brittle nature. On the other hand, the film produced from Comparative Example 1 also suffered from a problem that the film was broken when the degree of bending was strong due to lack of flexibility.

While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the above description does not limit the scope of the present invention, which is defined by the limitations of the following claims.

Claims (14)

A polymer matrix made from urethane acrylate having a viscosity of 100 to 1000 cps at 80 캜; And a colloid particle dispersed in the polymer matrix and arranged in a crystal lattice structure, the thickness being 10 to 200 mu m. The method according to claim 1,
The photonic crystal film for a security element has a maximum reflectance of 10% or more. delete delete delete In the first aspect,
Wherein the urethane acrylate has a weight average molecular weight of 500 to 30,000 g / mol. The method according to claim 1,
Wherein the refractive index difference between the polymer matrix and the colloidal particles is at least 0.02. 8. The method of claim 7,
Wherein the refractive index of the polymer matrix is 1.4 to 1.5 and the refractive index of the colloidal particles is 1.3 to 2.95. The method according to claim 1,
Wherein the average diameter of the colloidal particles is 50 to 315 nm. 10. The method of claim 9,
Wherein the colloidal particles satisfy the following relational expression (1).
[Relation 1]
Da x 0.95? Ds? Da x 1.05
(In the above relational expression 1, Ds is the particle diameter (nm) of the colloidal particles and Da is the average particle diameter (nm) of the colloidal particles.) The method according to claim 1,
Wherein the colloidal particles are any one or more selected from metal nanoparticles, metal oxide nanoparticles, organic nanoparticles, and carbon nanoparticles. An anti-fake article comprising a photonic crystal film for a foldable security element selected from any one of claims 1, 2, and 6 to 11. Comprising applying a dispersion comprising a urethane acrylate, a colloid particle and a photoinitiator having a viscosity of from 100 to 1000 cps at 80 캜 onto a substrate or injecting between two parallel transparent plates and irradiating light, Method for manufacturing photonic crystal film for element. 14. The method of claim 13,
Wherein the dispersion is applied on the substrate at a temperature of 60 to 100 DEG C or injected between the two transparent plates.

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