KR102479527B1 - Metal artefact with photonic crystal material and fabrication method thereof - Google Patents

Abstract

A body part including a metal material, a groove part formed in the body part, and an optically variable part formed by filling the groove part with a photonic crystal material, wherein the photonic crystal material has a crystal lattice structure in which colloidal particles are regularly dispersed in a polymer matrix. A metal processed product characterized in that a structural color is observed in an optical variable portion is disclosed. According to the present invention, there is an effect of improving aesthetics and security by providing a more colorful visual effect to the metal workpiece.

Description

Metal-processed product applied with an optical variable part including a photonic crystal material and method for manufacturing the same

The present invention relates to a metal workpiece to which an optical variable unit including a photonic crystal material is applied and a manufacturing method thereof.

As shown in FIG. 1, various technologies have been proposed to provide aesthetics and anti-counterfeiting effects by giving unique visual effects of various colors to metal processed products such as coins and medals.

Due to the nature of the metal material, it is impossible to implement various colors by itself, so a technique for implementing color through coloring or plating is sometimes used, but this technique has a problem in that the visual effect is simple and forgery is easy.

In order to give a more colorful visual effect, a technique for implementing the effect of changing color or image depending on the viewing angle by transferring or directly attaching a hologram consisting of a fine diffraction grating pattern to the surface of a metal has also been proposed. Compared to general coloring techniques or plating techniques, the difference in visual effect is not great, and the angular dependence is too high, so it is difficult to accurately identify the hologram effect even if the viewing angle is slightly different.

The present invention has been made to solve the problems of the prior art, and specifically, by applying a photonic crystal material containing fine colloidal particles to a metal workpiece, more diverse visual effects and improved anti-counterfeiting effects are implemented. Its purpose is to provide a metal processed product and its manufacturing method.

The object of the present invention is not limited to the above, and other objects and advantages of the present invention not mentioned can be understood by the following description.

A metal workpiece according to an embodiment of the present invention includes a body portion including a metal material, a groove portion formed in the body portion, and an optically variable portion formed by filling the groove portion with a photonic crystal material, wherein the photonic crystal material is colloidal particles in a polymer matrix. It is characterized in that they are regularly dispersed to form a crystal lattice structure, and a structural color is observed in the light-changing portion.

The structural color may appear as a mixture of reflected light reflected by the photonic crystal material and transmitted light transmitted through the photonic crystal material and reflected from the bottom surface of the groove. It can vary.

A plurality of light-changing units may be provided, and different visual effects may be obtained from the plurality of light-changing units.

The light-changing unit may include a first region formed of a photonic crystal material having a first thickness and a second region formed of a photonic crystal material having a second thickness different from the first thickness, wherein the first region and the second region may have different visual effects. In this case, the first thickness and the second thickness of the photonic crystal material may be determined by the depth of the groove.

In addition, the light-changing part includes a first area having a first reflectance on the bottom surface of the groove and a second area having a second reflectance different from the first reflectance on the bottom surface of the groove, and Visual effects in the second area may be different from each other. In this case, the second region includes a reflectance adjusting unit on the bottom surface of the groove, the reflectance adjusting unit reduces the reflectance of the bottom surface of the groove, and the reflectance adjusting unit may be a light absorption coating or a surface roughness increasing area. In addition, the structural color observed in the first region is relatively close to the reflected light reflected by the photonic crystal material, and the structural color observed in the second region is transmitted light transmitted through the photonic crystal material and reflected from the bottom surface of the groove. can be relatively close to

The reflectance adjusting unit may be formed in a predetermined pattern.

A metal workpiece according to another embodiment of the present invention includes a body portion including a metal material, a through hole formed in the body portion, and an optically variable portion formed by filling the through hole with a photonic crystal material, wherein the photonic crystal material is in a polymer matrix. It is characterized in that colloidal particles are regularly dispersed to form a crystal lattice structure, and a structural color is observed in the light-variable part.

The light-changing unit includes a substrate disposed on an upper or lower surface of the photonic crystal material, and the substrate may be made of a light-transmitting material.

In addition, the structural color may be relatively close to reflected light reflected by the photonic crystal material when observed in the same direction as illumination, and relatively close to transmitted light passing through the photonic crystal material when observed in a direction different from illumination. In this case, the reflected light and the transmitted light may have a complementary color relationship.

In addition, a pattern portion blocking transmission of light may be formed on at least one surface of the light-changing portion.

In addition, in the above-described embodiments of the present invention, the light-changing part may be formed by dispersing a photonic crystal material in the form of a thin sheet in a transparent resin.

A method for manufacturing a metal workpiece according to an embodiment of the present invention includes the steps of forming grooves or through-holes in a body portion including a metal material, dispersing colloidal particles in a polymer matrix and then applying them to the grooves or through-holes; It is characterized in that it includes the step of structuring the colloidal particles and the step of curing the polymer matrix.

Alternatively, preparing a photonic crystal material by dispersing colloidal particles in a polymer matrix, crystallizing the colloidal particles and curing the polymer matrix, forming grooves or through-holes in a body part including a metal material, and the manufacturing process and applying the photonic crystal material to the groove or through hole.

At this time, the viscosity of the polymer matrix may have a viscosity of 100 to 3000 cP, and the step of structuring the crystal may be a step of maintaining at 30 to 50 ° C.

According to the present invention, by applying the light-changing part including the photonic crystal material including fine colloidal particles to at least a portion of the metal workpiece, there is an effect that can provide more various visual effects and improved anti-counterfeiting effect.

More specifically, fine colloidal particles are regularly arranged to implement an aesthetic reflective color appearing in jewels, as well as to implement a color conversion effect with reduced angular dependence.

In addition, since the reflected color and the transmitted color can be implemented to have a complementary color relationship, there is an effect that can simultaneously implement a forgery prevention effect as well as a unique visual effect according to the structure of the light tunable unit.

However, the effects of the present invention are not limited to those mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description below.

1 is examples of metal-processed products to which a conventional optical variable element is applied.
2 and 3 are views for explaining a metal workpiece to which an optical variable unit including a photonic crystal material according to a first embodiment of the present invention is applied.
4 and 5 are views for explaining a metal workpiece to which an optical variable unit including a photonic crystal material according to a second embodiment of the present invention is applied.
6 is a view for explaining a metal workpiece to which an optical variable unit including a photonic crystal material according to a third embodiment of the present invention is applied.
7 is a view for explaining a metal workpiece to which an optical variable unit including a photonic crystal material according to a fourth embodiment of the present invention is applied.
8 is a view for explaining a metal workpiece to which an optical variable unit including a photonic crystal material according to a modified example of the fourth embodiment of the present invention is applied.
9 is a view for explaining a metal workpiece to which an optical variable unit including a photonic crystal material according to a fifth embodiment of the present invention is applied.
10 is a flowchart of a method for manufacturing a metal workpiece according to the present invention.
11 is a photograph comparing the visual effect according to the reflectance of the bottom surface of the groove in the metal workpiece according to the first embodiment of the present invention.
12 is a visual inspection showing a visual effect of a metal workpiece according to a fourth embodiment of the present invention.
13 is a photograph for explaining the visual effect of the fifth embodiment of the present invention.

Hereinafter, various embodiments of the present invention will be described in detail with reference to the accompanying drawings. Embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art. The embodiments presented below may be modified in many different forms, and the scope of the present invention is not limited to the following embodiments, and all changes, equivalents or substitutes included in the spirit and technical scope of the present invention should be understood as including

Like reference numerals may be used for like elements while describing the accompanying drawings. In the accompanying drawings, the dimensions of the structures may be shown enlarged or reduced than actual to help a clear understanding of the present invention.

Terms used in this specification are only used to describe specific embodiments, and are not intended to limit the present invention.

In this specification, terms such as “include” or “having” specify the presence of the listed features, but should be understood as not precluding the possibility of the presence or addition of one or more other features.

In this specification, the term 'metal workpiece' should be understood to include not only metal workpieces having a relatively flat shape, such as coins, medals, and medals, but also metal workpieces having complex curved shapes, such as watches and rings. At this time, the metal workpiece does not have to be formed entirely of metal in its entire volume, and refers to a workpiece in which metal is exposed on at least a part of its surface, such as a metal material coated on a non-metallic material. Also, it should be understood that the term includes not only a workpiece having a physically exposed metal surface, but also a workpiece having at least a visually metallic surface, such as having a transparent coating formed on the metal.

In addition, in this specification, the term 'structural color' should be understood as a meaning encompassing a color represented by the structure of a material, and should not be construed as limiting in an academic sense. That is, in the present specification, 'structural color' may include all colors implemented by reflected light, transmitted light, and mixed light obtained by mixing reflected light and transmitted light, which are represented by the structure of a material.

2 and 3 are views for explaining a metal workpiece to which an optical variable unit including a photonic crystal material according to a first embodiment of the present invention is applied. 2 is a perspective view of a metal workpiece, and FIG. 3 is a cross-sectional view along line A-A of FIG.

Referring to FIGS. 2 and 3 , the metal workpiece 100 according to the first embodiment of the present invention may include a body portion 20 and an optically variable portion 10 . The body portion 20 is a portion containing a metallic material. The body portion 20 may be entirely made of a metal material, such as a metal coin or medal, or at least a portion thereof may be made of a metal material. Here, a portion made of a metal material may be a portion where the light-changing portion 10 is formed.

The light-changing unit 10 may include a photonic crystal material. Specifically, the photonic crystal material may be filled in the groove 21 formed in the body portion 20 to form the light-changing portion 10 . The groove 21 may be concavely formed on the surface of the body 20 to a predetermined depth. As shown in FIG. 3 , the photonic crystal material may be a material in which fine colloidal particles 12 are regularly dispersed in a polymer matrix 11 .

Here, the polymer matrix 11 is ethoxylated trimethylolpropane triacrylate, ethoxylated pentaerythritol tetraacrylate, pentaerythritol triacrylate, dipentaerythritol pentaacrylate and trimethylolpropane triacrylate, poly It is preferably a polymer derived from any one or more mixtures selected from propylene glycol acrylate, polypropylene glycol dimethacrylate, polyethylene glycol diacrylate and polyethylene glycol dimethacrylate.

In addition, it is preferable that the colloidal particles 12 be a material having a refractive index similar to that of the polymer matrix 11 so that they can be dispersed in the polymer matrix 11 and arranged in a regular crystal lattice structure. Specifically, it is more preferable that the refractive index is the same as that of the polymer matrix 11 or the refractive index difference is 0.5 or less. Illustratively, the colloidal particle 12 may be any one of a metal oxide, a polymer, and a carbon structure. For example, when the polymer matrix 11 is ethoxylated trimethylolpropane triacrylate, it is preferable to use silica or polystyrene as the colloidal particles 12 .

In addition, the colloidal particles 12 may be spherical particles having a diameter of 1 μm or less, and preferably have a diameter of about 100 nm to 500 nm.

The photonic crystal material has a crystal lattice structure in which fine colloidal particles 12 are arranged at regular intervals to form a crystal lattice structure having a photonic band gap, so that wavelength-selective reflection characteristics may be exhibited according to Equation 1 below. Here, m is an integer representing the diffraction order, λ is the wavelength of the reflected light, d is the distance between the colloidal particles 12, n _eff is the effective refractive index of the photonic crystal material, and θ is the incident angle of light to the photonic crystal material (of the photonic crystal material angle between the normal and the incident light).

(Equation 1)

According to Equation 1 above, the photonic crystal material selectively reflects only light of a specific wavelength (λ) and transmits light of other wavelengths. Accordingly, a structural color of a specific wavelength may appear.

That is, when the distance d between the colloidal particles decreases, only relatively short wavelengths of light can be reflected and the rest of the wavelengths can be transmitted. Therefore, when the reflected light is observed, a blue-based structural color may appear. Conversely, when the distance d between the colloidal particles increases, only relatively long wavelengths of light can be reflected and the rest of the wavelengths can be transmitted. Therefore, when the reflected light is observed, a red-based structural color may appear.

In the metal workpiece 100 according to the first embodiment of the present invention, a unique structural color can be observed due to the photonic crystal material included in the light-changing part 10 . That is, the structural color determined by the effective refractive index (n _eff ) of the photonic crystal material, the spacing (d) between colloidal particles, and the incident angle can be observed.

In particular, in the present invention, by applying a photonic crystal material to a metal workpiece, unlike a general photonic crystal material, a unique effect in which reflected light and transmitted light are mixed and observed can be obtained. Referring to FIG. 3 in more detail, the metal workpiece 100 according to the first embodiment of the present invention can obtain an effect in which the observed structural color varies according to the reflectance of the bottom surface of the groove portion 21. That is, when the bottom surface of the groove part 21 is made of a metal material with high reflectance, the wavelength of light reflected from the bottom surface of the groove part 21 after passing through the photonic crystal material in addition to the wavelength of light reflected from the photonic crystal material (λ in Equation 1) is Mixed colors can be observed. According to this principle, when the reflectance of the bottom surface of the groove 21 is low, the structural color observed by the observer may be close to the wavelength (λ) of the reflected light determined by Equation 1, and as the reflectance of the bottom surface increases, the photonic crystal material is transmitted. Structural colors close to the wavelength of the light can be observed.

In addition, there may be a difference in visual effects observed according to the thickness of the photonic crystal material. If the photonic crystal material is thick, overall transparency decreases due to scattering inside the material, and the degree of observation of light reflected from the bottom surface of the groove 21 may be reduced. The thickness of the photonic crystal material may be adjusted by the formation depth of the groove 21 .

Therefore, in the case of the metal workpiece 100 according to the first embodiment of the present invention, even if the same photonic crystal material is applied, various visual effects can be obtained depending on the design of the groove 21 (depth of the groove, reflectance of the bottom surface of the groove, etc.) there is

In addition, in the metal workpiece 100 according to the first embodiment of the present invention, when the observation angle changes, the incident angle, that is, θ changes, so the color of the observed reflected light also changes. Therefore, when the metal workpiece 100 is observed from various angles, the effect of changing the color of the light-changing part 10 can be observed. This can give security as well as aesthetics to the metal workpiece 100 .

Although only one groove part 21 is shown in FIGS. 2 and 3, a plurality of groove parts 21 may be provided. For example, the grooves 21 may be formed on both sides of the body 20 and filled with a photonic crystal material to form a plurality of light-changing parts. In this case, it is possible to observe visual effects by the light-changing part on both sides of the metal-worked product. In addition, when the depth of each groove part 21 and the reflectance of the bottom surface of each groove part 21 are made different, different visual effects can be obtained in each light-changing part.

4 and 5 are views for explaining a metal workpiece to which an optical variable unit including a photonic crystal material according to a second embodiment of the present invention is applied. The second embodiment of the present invention is different from the first embodiment in that the depth of the groove portion 21 is not uniform. For this reason, the thickness of the photonic crystal material included in the light-changing unit 10 is different depending on the region. In describing the metal workpiece according to the second embodiment, descriptions of the same parts as those of the first embodiment may be omitted.

Referring to FIG. 4 , the metal workpiece 200 according to the second embodiment of the present invention may include a body portion 20 and an optically variable portion 10 . The light-changing part 10 may be formed by filling a groove 21 formed to a predetermined depth on the surface of the body part 20 with a photonic crystal material. In this case, the depth of the groove 21 may not be uniform for each area. As exemplarily shown in FIG. 4 , the first area A may be formed with a relatively shallow first depth, and the second area B may be formed with a relatively deep second depth. That is, the groove part 21 may include at least one level difference. For this reason, the thickness of the photonic crystal material of the light-changing unit 10 may be different for each region. That is, the thickness of the photonic crystal material in the second region (B) may be thicker than that of the photonic crystal material in the first region (A) in FIG. 4 .

According to the second embodiment, there is an effect that the visual effect observed in the light-changing unit 10 is different for each area of the metal workpiece. In the first region A, where the thickness of the photonic crystal material is relatively thin, a transparent and clearer structural color may be observed. On the other hand, in the second region (B) where the thickness of the photonic crystal material is relatively thick, an opaque and more cloudy structural color may be observed.

In FIG. 4, it has been described that the depth of the groove portion 21 is different for each region due to the step formed in the groove portion 21, but the second embodiment of the present invention is not limited thereto. For example, as shown in FIG. 5, the groove 21 may be formed as a curved surface so that the depth continuously changes. In this case, since the thickness of the photonic crystal material filled in the groove 21 continuously changes, structural colors and visual effects that continuously change according to positions can be observed.

6 is a view for explaining a metal workpiece to which an optical variable unit including a photonic crystal material according to a third embodiment of the present invention is applied. The metal workpiece according to the third embodiment of the present invention is different from the first embodiment in that a reflectance adjusting part is further provided on a part of the bottom surface of the groove part 21. For this reason, there may be a difference in reflectance at the bottom surface of the groove part 21 for each area of the light-changing part 10 . In describing the metal workpiece according to the third embodiment, descriptions of the same parts as those of the first embodiment may be omitted.

Referring to FIG. 6 , the metal workpiece 300 according to the third embodiment of the present invention may include a body part 20 and an optically variable part 10 . The light-changing part 10 may be formed by filling a groove 21 formed to a predetermined depth on the surface of the body part 20 with a photonic crystal material. In this case, the depth of the groove 21 may be uniform or non-uniform for each region.

A reflectance adjusting unit 30 is provided on a portion of the bottom surface of the groove 21 . The reflectance at the bottom of the groove 21 is changed by the reflectance adjusting unit 30 . The reflectance may be reduced by the reflectance adjuster 30 . As exemplarily shown in FIG. 6 , the reflectance at the bottom surface of the groove part 21 is higher than that of the first area A1 in which the reflectance adjusting unit 30 is not formed, in the second area where the reflectance adjusting unit 30 is formed ( It may be lower in B1).

The reflectance adjusting unit 30 may be formed using a light absorption coating or may be formed by varying the surface roughness of the bottom surface of the groove 21 . For example, the second region B1 in which the reflectance adjusting unit 30 is formed may be a region in which a light absorption coating is formed on the bottom surface of the groove 21 or the surface is relatively rough.

According to the third embodiment, there is an effect that the visual effect observed in the light-changing part 10 is different for each area of the metal workpiece. In the first area A1 where the reflectance adjusting unit 30 is not formed, since a relatively large amount of reflection occurs on the bottom surface of the groove 21, the wavelength of light reflected from the photonic crystal material (λ in Equation 1) and the photonic crystal material are transmitted. After that, a mixed color of wavelengths of light reflected from the bottom surface of the groove 21 can be observed. On the other hand, in the second area B1 where the reflectance adjusting unit 30 is formed, reflection from the bottom surface of the groove 21 is relatively small, so the structural color is closer to the wavelength of light reflected from the photonic crystal material (λ in Equation 1). this can be observed.

The reflectance adjusting unit 30 is not limited to a configuration that reduces reflectance. Conversely, it may be configured to increase the reflectance. In this case, since the reflected light from the bottom surface of the groove part 21 is increased in the second region B1 where the reflectance adjusting part 30 is formed, the wavelength of the light reflected from the photonic crystal material (λ in Equation 1) and the photonic crystal material pass through the groove part 21 ) A color in which the wavelengths of light reflected from the bottom surface are mixed can be observed.

The reflectance adjusting unit 30 may be formed in a predetermined pattern. For example, it may be formed as a predetermined character or pattern. In this case, since the pattern by the reflectance adjusting unit 30 is observed together with the structural color of the light-changing unit 10, more colorful visual effects can be provided.

7 is a view for explaining a metal workpiece to which an optical variable unit including a photonic crystal material according to a fourth embodiment of the present invention is applied. The fourth embodiment of the present invention is different from the first embodiment in that a through hole is formed in the body portion 20 instead of a groove, and a light-changing part is formed in the through hole. This has the effect of being able to observe both the structural color by reflection and the structural color by transmission of the photonic crystal material according to the relative position of the observer and the light. In describing the metal workpiece according to the fourth embodiment, descriptions of the same parts as those of the first embodiment may be omitted.

Referring to FIG. 7 , a metal workpiece 400 according to a fourth embodiment of the present invention may include a body portion 20 and an optically variable portion 10 . The light-changing part 10 may be formed by filling a through hole 22 formed from the upper surface to the lower surface of the body part 20 with a photonic crystal material. Optionally, the light-changing part 10 may include a first substrate 41 and/or a second substrate 42 . That is, the light-changing unit 10 may be formed in a form in which a photonic crystal material is filled between the first substrate 41 and the second substrate 42 . The first substrate 41 and the second substrate 42 are not necessarily required, and only the first substrate 41 may be included or both may be omitted. At least a portion of the first substrate 41 and the second substrate 42 may be made of a light-transmitting material. For example, it may be made of transparent or translucent glass or polymer material.

According to the fourth embodiment of the present invention, the structural color of the light-changing part 10 can be observed from both the upper and lower parts of the metal workpiece, and at this time, different structural colors can be observed from the upper and lower parts. . Assuming that the lighting is located at the top in FIG. 7 , of the light incident from the lighting to the light tunable unit 10, light corresponding to some wavelength (λ in Equation 1) is reflected back to the top, and the remaining wavelengths can be transmitted. . Therefore, when observing in the same direction as the illumination, for example, from the top of the metal workpiece in FIG. 7 , reflected light from the light-changing unit 10 can be observed. In addition, when observing in a direction different from the lighting, for example, from the lower part of the metal workpiece in FIG. 7 , transmitted light transmitted through the light-changing part 10 can be observed. At this time, since the reflected light and the transmitted light have a complementary color relationship, different colors can be observed depending on the direction in which the metal workpiece is observed.

In other words, by forming a through hole in a metal workpiece and filling it with a photonic crystal material, when viewed from above, the structural color due to the reflected light unique to the photonic crystal material can be observed, and when viewed under light, the structural color and It is possible to observe structural colors by transmitted light in a complementary color relationship. For example, when a metal workpiece is viewed from above, green color is observed, and when it is observed under illumination, red, which is a complementary color of green, may be observed. Due to this, it is possible to provide more colorful visual effects and security to the metal workpiece.

FIG. 8 is a view for explaining a metal workpiece to which an optically variable part including a photonic crystal material according to a modified example of the fourth embodiment of the present invention is applied. Compared to the fourth embodiment of FIG. 7 , at least There is a difference in that the pattern unit 50 is formed on one side. The pattern unit 50 may be formed of a material that at least partially blocks transmission of light. For example, the pattern unit 50 may be formed by printing a predetermined pattern, such as a character or pattern, with colored ink on the surface of the first substrate 41 . According to this structure, when the metal workpiece 400A is observed under transmitted light, the text or pattern formed by the pattern portion 50 can be observed together with the structural color due to the transmitted light.

9 is a view for explaining a metal workpiece to which an optical variable unit including a photonic crystal material according to a fifth embodiment of the present invention is applied. The fifth embodiment of the present invention is different from the first embodiment in that the photonic crystal material is included in the light tunable part in the form of flakes. As a result, the structural color is observed only in the flake portion of the light-changing portion, and more colorful visual effects are provided according to the shape or direction of the flake. In describing the metal workpiece according to the fifth embodiment, descriptions of the same parts as those of the first embodiment may be omitted.

Referring to FIG. 9 , a metal workpiece 500 according to a fifth embodiment of the present invention may include a body portion 20 and an optically variable portion 10 . The light-changing part 10 may be formed by filling the groove part 21 formed in the body part 20 with a photonic crystal material. Alternatively, as described in the fourth embodiment of FIG. 7 , the through hole may be filled with a photonic crystal material.

Meanwhile, in the fifth embodiment of the present invention, a photonic crystal material is included in the light-changing part 10 in the form of a thin slice 16 . That is, as shown in FIG. 9( b ), only the light-changing portion 10 is enlarged, the photonic crystal materials 16 in the form of flakes may be dispersed in the transparent resin 13 to form the light-changing portion 10 . At this time, the flake-shaped photonic crystal material 16 may be a material in which colloidal particles 12 are regularly dispersed in the polymer matrix 11 as in other embodiments. In this case, the polymer matrix 11 constituting the photonic crystal material 16 and the transparent resin 13 in which the photonic crystal material 16 is dispersed may be the same material.

According to the fifth embodiment of the present invention, since the structural color is observed only in the flake portion among the entire area of the light-changing portion 10, more colorful visual effects are provided according to the shape or direction of the flake.

10 is a flowchart of a method for manufacturing a metal workpiece according to the present invention.

Referring to FIG. 10, the method for manufacturing a metal workpiece according to the present invention includes forming grooves on the body (S10), dispersing colloidal particles in a polymer matrix and then applying them to the grooves (S20), colloidal particles It may include a step of structuring the crystal (S30) and a step of curing the polymer matrix (S40).

First, forming a groove in the body (S10) is a step of forming a concave region in which the light-changing portion 10 is to be formed in the body 20 of the metal workpiece as exemplarily described with reference to FIG. 1 and the like. to be. The groove part 21 may be formed to a certain depth in the body part 20 or may be formed to a different depth for each region.

Also, step S10 may be replaced with a step of forming through holes instead of grooves.

Next, after dispersing fine colloidal particles in the polymer matrix and applying them to the grooves (S20), a step of structuring the colloidal particles into crystals (S30) may be performed.

At this time, it is preferable to provide an appropriate environment in order for the colloidal particles to be regularly arranged by self-assembly in the polymer matrix to form a crystal structure. Here, the appropriate environment may mean the viscosity of the polymer matrix, ambient temperature, etc. .

The viscosity of the polymer matrix is preferably 5,000 cP or less, and more specifically, about 100 cP to 3,000 cP. When the viscosity of the polymer matrix is too low, the colloidal particles move too easily and are difficult to arrange in a lattice structure.

In addition, since the viscosity has a property that changes according to the ambient temperature, it is preferable that the ambient temperature is about 70 ° C or less, more specifically, 30 ° C to 30 ° C. It is preferable that it is about 50 degreeC.

After the colloidal particles are crystal structured, a step of curing the polymer matrix to prevent the colloidal particles from moving any further may be performed (S40). At this time, as a curing method, various methods such as thermal curing and ultraviolet curing may be used. In order to use UV curing, an additive such as a photoinitiator that reacts to UV light may be included in the polymer matrix.

In FIG. 10, it has been described that colloidal particles are dispersed in a polymer matrix and then applied to grooves before crystal structuring (S30) and curing (S40), but the present invention is not limited thereto. For example, after colloidal particles are dispersed in a polymer matrix, crystal structuring and curing of the colloidal particles are performed, the cured photonic crystal material may be applied to the grooves formed in the body to form the light-changing part.

In addition, a separate primer layer may be added to improve adhesion between the photonic crystal material and the bottom surface of the groove.

Hereinafter, the effects of the present invention will be further described with reference to photographs of a coin-type metal workpiece to which the optical variable unit according to embodiments of the present invention is applied.

11 is a photograph comparing the visual effect according to the reflectance of the bottom surface of the groove in the metal workpiece according to the first embodiment of the present invention. FIG. 11(a) is a photograph of a case in which reflectance is low by forming the bottom surface of the groove with a matte surface, and FIG.

As confirmed in FIG. 11 , although the same photonic crystal material is applied, it can be seen that the observed structural color is different according to the reflectance of the bottom surface of the groove. In the case of FIG. 11(a) in which the bottom surface of the groove is formed of a matte surface, a color close to green, which is a structural color due to the wavelength of light reflected from the photonic crystal material (λ in Equation 1), is observed, whereas the bottom surface of the groove is formed of a glossy surface. In the case of 11(b), in addition to the wavelength of light reflected from the photonic crystal material (λ in Equation 1), the wavelength of light transmitted through the photonic crystal material and reflected from the bottom surface of the groove is mixed, and a color close to red, a complementary color to green, is observed.

12 is a test showing a visual effect of a metal workpiece according to a fourth embodiment of the present invention, and is an example in which a light-changing part including a photonic crystal material is applied to a through hole formed in a body part. Figure 12 (a) is a case of observing in the same direction as the light, and Figure 12 (b) is a case of observing with light from a different direction from the light.

As confirmed in FIG. 12 (a), when observing in the same direction as the illumination, green, which is a structural color due to the wavelength of light reflected from the photonic crystal material (λ in Equation 1), is observed. On the other hand, as shown in FIG. 12(b), when observing the light from a different direction than the light, red, which is a complementary color to green, is observed because the light transmitted through the photonic crystal material is observed.

13 is a photograph for explaining the visual effect of the fifth embodiment of the present invention, in which a photonic crystal material is made into thin slices, mixed with transparent resin, and then coated on a black substrate (paper) and cured. As confirmed in FIG. 13 , in the transparent resin part without the photonic crystal material, only the black substrate is observed, and the reflected light, green color, is observed only in the part with the photonic crystal material.

Although described above with reference to the limited embodiments and drawings, these are only examples, and it will be apparent to those skilled in the art that various modifications and implementations are possible within the scope of the technical idea of the present invention. For example, all or parts of each embodiment may be selectively combined. Therefore, the protection scope of the present invention should be defined by the description of the claims and their equivalents.

100, 200, 300, 400, 500: metal processed products
10: light variable unit
11: polymer matrix
12: colloidal particles
13: transparent resin
16: thin slices
20: body part
21: groove part
22: through hole
30: reflectance adjustment unit
41: first substrate
42: second substrate
50: pattern part

Claims (19)

Body portion including a metal material;
a groove formed in the body;
an optical variable portion formed by filling the groove with a photonic crystal material;
including,
The photonic crystal material has a crystal lattice structure in which colloidal particles are regularly dispersed in a polymer matrix.
Structural color is observed in the light-changing part,
The light variable part,
A first region in which a bottom surface of the groove has a first reflectance;
The bottom surface of the groove includes a second region having a second reflectance different from the first reflectance,
A metal-worked product, characterized in that different visual effects appear in the first region and the second region due to the difference in reflectance between the first region and the second region. According to claim 1,
The structural color is characterized in that the reflected light reflected by the photonic crystal material and the transmitted light transmitted through the photonic crystal material and reflected from the bottom surface of the groove portion appear as a mixture. According to claim 1,
The structural color is a metal processed product, characterized in that varies depending on the reflectance of the bottom surface of the groove. According to claim 1,
The optical variable unit is provided with a plurality of pieces,
A metal processed product, characterized in that different visual effects are obtained from the plurality of light-changing parts. According to claim 1,
The light variable part,
A first region in which a photonic crystal material is formed to a first thickness;
The photonic crystal material includes a second region formed with a second thickness different from the first thickness,
A metal processed product, characterized in that the visual effects in the first area and the second area are different from each other. According to claim 5,
The metal processed product, characterized in that the first thickness and the second thickness of the photonic crystal material is determined by the depth of the groove. delete According to claim 1,
The second region includes a reflectance adjusting part on the bottom surface of the groove part,
The reflectance of the bottom surface of the groove is reduced by the reflectance adjusting unit,
The metal workpiece, characterized in that the reflectance adjusting portion is a light absorption coating or a surface roughness increasing area. According to claim 1,
The structural color observed in the first region is relatively close to the reflected light reflected by the photonic crystal material,
The structural color observed in the second region is relatively close to the transmitted light transmitted through the photonic crystal material and reflected from the bottom surface of the groove. According to claim 8,
The metal workpiece, characterized in that the reflectance adjusting portion is formed in a predetermined pattern. Body portion including a metal material;
a through hole formed in the body;
a light-changing part formed by filling the through hole with a photonic crystal material;
including,
The photonic crystal material has a crystal lattice structure in which colloidal particles are regularly dispersed in a polymer matrix.
Structural color is observed in the light-changing part,
A metal-worked product, characterized in that a pattern portion for blocking transmission of light is formed on at least one surface of the light-changing portion. According to claim 11,
The light variable part,
Including a substrate disposed on the upper or lower surface of the photonic crystal material,
The substrate is a metal processed product, characterized in that made of a light-transmitting material. According to claim 11,
The structural color is
When observed in the same direction as the illumination, it is relatively close to the reflected light reflected by the photonic crystal material,
A metal workpiece, characterized in that it is relatively close to the transmitted light passing through the photonic crystal material when observed from a direction different from illumination. According to claim 13,
The metal-worked product, characterized in that the reflected light and the transmitted light are complementary to each other. delete According to claim 1 or 11,
The light variable part,
A metal processed product characterized in that it is formed by dispersing a photonic crystal material in the form of flakes in a transparent resin. delete delete delete

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