KR102434848B1 - A method of manufacturing a variable heterogeneous surface composite with improved water resistance and contamination resistance, and Anti-fake device using the same - Google Patents

Abstract

The present invention relates to a method for manufacturing a deformable heterogeneous surface composite with improved water resistance and contamination resistance, and a forgery prevention device using the same. The method for manufacturing a deformable heterogeneous surface composite, according to the present invention, comprises the steps of: forming a base substrate; forming a high-hard layer; forming an intermediate-hard layer; and curing the high-hard layer and the intermediate-hard layer. According to the present invention, the degree of freedom of the existing passive optical hologram forgery prevention device for forgery prevention can be increased.

Description

{A method of manufacturing a variable heterogeneous surface composite with improved water resistance and contamination resistance, and Anti-fake device using the same}

The present invention relates to a variable heterogeneous surface complex with improved water resistance and stain resistance and an anti-counterfeiting device using the same. It relates to a variable type heterogeneous surface composite that can significantly reduce the occurrence rate of contamination and defective products that may occur in the distribution and storage environment of products by improving the physical properties of the part directly receiving it, and a counterfeit prevention device using the same.

In modern times, various new products are being developed according to the development of technology, and the developed products are actively traded online. Unfortunately, however, the reproduction technology has also made great progress, making it difficult to distinguish the original from the replica. In the case of high-priced products, various anti-counterfeiting technologies are applied, but in the case of low-priced products that are unavoidable in mass distribution, it is difficult to apply them. It seems to require social attention.

In the case of a forgery prevention system with a photonic crystal-based pattern, which is commonly used among forgery prevention technologies, it is always visible in the presence of light, which is not suitable for hiding information.

Accordingly, many developments have been made for a new type of anti-counterfeiting device that has a fast response to various external stimuli (tension, compression, bending, torsion, etc.). However, in the case of an anti-counterfeiting device having a responsiveness to external stimuli, it is easy to contamination by fingerprints, dust, etc. on the part to which external stimuli are applied, and it is also vulnerable to contact with moisture, so there are some restrictions on the semi-permanent use of the anti-counterfeiting system. existed. On the other hand, although it is possible to improve the stain resistance by applying various materials to solve this problem, there is a problem that the deformation of the complex occurs easily due to external stimuli. Therefore, there is a need to improve the physical properties of the part in direct contact with the external stimulus.

(Patent Document 0001) 『Republic of Korea Patent Publication No. 10-2018-0126710, Title of Invention: Photonic crystal film, manufacturing method thereof, and anti-counterfeiting article including same, (published date: November 28, 2018, Applicant: Korea) Mint Corporation, Korea Advanced Institute of Science and Technology)

The present invention allows the optical hologram providing means to hide or show images depending on external stimuli, as well as to make the stress distribution by external stimuli and the resulting strain formed differently for each set area, and at the same time improve water resistance and contamination resistance. To provide a variable type heterogeneous surface composite that can be used semi-permanently by preventing contamination by fingerprints, dust, etc. through the use of hydrophobic materials and improving durability by using a hard material with specific physical properties, and an anti-counterfeiting device using the same. do.

According to one aspect of the present invention for achieving this object, the present invention is formed of a flexible low-hard material, the base material comprising a high wrinkled region and a low wrinkled region adjacent to the high wrinkled region; a high hard layer formed in a pattern on an upper portion of the high wrinkle region and made of a high hard material having a Young's modulus greater than that of the low hard material; and a medium-hard layer that covers the low-wrinkle region and the high-hard layer, has a Young's modulus larger than that of the low-hard material and smaller than the high-hard material, and is formed of a medium-hard material including acrylic; and the medium-hard material includes It provides a deformable heterogeneous surface composite, characterized in that it contains a reinforcing material having at least any one of greater yield strength, tensile strength, impact strength and shear strength than the acrylic based on a specimen of the same size and shape.

According to another aspect of the present invention, the present invention is formed of a flexible low-hard material, comprising the steps of: preparing a base material comprising a high wrinkled region and a low wrinkled region adjacent to the high wrinkled region; forming a high hard layer formed in a pattern on the high wrinkle area and made of a high hard material having a Young's modulus greater than that of the low hard material; forming a medium hard layer covering the low wrinkle region and the high hard layer, having a Young's modulus larger than the low hard material and smaller than the high hard material, and formed of a medium hard material including acrylic; It provides a method for manufacturing a variable heterogeneous surface composite comprising the step of preparing a composite by curing the high hard layer and the medium hard layer.

According to another aspect of the present invention, the present invention provides an anti-counterfeiting device including the variable heterogeneous surface composite of the above-described solution.

According to the present invention, there are the following effects.

First, by using the characteristic of forming a wrinkle pattern based on the instability of the buckling type on the high hard layer by external stimuli, it actively hides or shows the structural color that can form a specific image, thereby preventing the existing passive optical hologram forgery. It is possible to increase the degree of freedom for preventing forgery of the device.

Second, there is an advantage that can prevent contamination by fingerprints, dust, etc. of the forgery prevention device by improving the physical properties of the medium and hard layer in contact with the external stimulus in the forgery prevention device of the present invention that determines whether forgery or not in response to an external stimulus.

Third, by improving the stain resistance and durability of the anti-counterfeiting device of the present invention that determines whether forgery or not in response to an external stimulus, the incidence of defective products can be significantly reduced, and semi-permanent use is possible.

Fourth, compared to the case of using only acrylic as a medium-hard material, a composite with a reinforcing material having at least any one of greater yield strength, tensile strength, impact strength and shear strength than acrylic and acrylic is used to prevent deformation due to external stimuli. It can have high breaking stress and strain, and can also maintain light transmittance due to the similar transmittance of the liver due to the use of a reinforcing material having a transmittance similar to that of acrylic.

Fifth, if the hard high-hard layer pattern is printed by inkjet or silk screen printing method, it includes the effect of producing a more inexpensive and convenient grating composite.

1 to 4 are views for explaining a method of manufacturing a variable heterogeneous surface composite according to an embodiment of the present invention.
5 is a schematic diagram showing that cracks occur when an external stimulus (bending) is applied to a variable type heterogeneous surface composite using only acrylic as a medium-hard material of the present invention;
6 shows the actual surface of the deformable heterogeneous surface composite when cracks occur, and it can be confirmed that the cracks occurred through the fact that the light passing through the middle region of the film is weak and has an opaque color.
7 is a variable heterogeneous surface composite 100 using a composite mixed with acrylic and cellulose as a medium hard material. Even when an external stimulus is applied, cracks do not occur in the internal material, so that the surface of the variable heterogeneous surface composite 100 is clean. indicates.
8 shows the results of stain resistance and water resistance tests on the variable heterogeneous surface composite according to an embodiment of the present invention. It can be seen that the pattern is maintained even after washing in water several times. Also, it can be confirmed that the film performance is not affected and the anti-counterfeiting function works properly even when rubbed repeatedly.

A method of manufacturing the variable heterogeneous surface composite 100 with improved durability and stain resistance will be described with reference to FIGS. 1 to 4 according to an embodiment of the present invention.

In order to manufacture the deformable heterogeneous surface composite 100 with improved durability and stain resistance, first, a substrate RB made of polyethylene terephthalate (PET) material on which the deformable heterogeneous surface composite of the present invention is to be laminated is prepared.

Thereafter, the base substrate 111 is formed by curing epoxy (EPU) on the upper surface of the substrate RB according to FIG. 2( a ). Here, it is preferable that the base material has a thickness of 200 to 300 μm from the viewpoint of not destroying the deformable heterogeneous surface complex by being separated from the substrate by an external stimulus. The base material should have a structure (flexible) that can be easily deformed by external stimuli, and if it has a thickness exceeding the above range, the manufacturing cost is increased, and the thickness is not suitable for use as a film, Furthermore, when there is an external stimulus, for example, a stimulus by bending, the deformable heterogeneous surface complex has a disadvantage in that it is not easily bent. On the other hand, when the base substrate has a thickness less than the above range, the durability is weakened, and the variable heterogeneous surface composite may be destroyed by external stimuli, and the stability of the substrate itself is lowered, so that when wrinkles are formed by bending, a uniform size Since wrinkles of random size can be formed rather than the wrinkles of

Here, the external stimulus that can be applied to the deformable heterogeneous surface complex may be a single load of compressive, tensile, or torsional loads including bending loads, or may be two or more complex loads, and the compressed deformation formed in the complex may be such compressive, tensile, or torsional loads. It may be deformed by bending or torsional load.

On the other hand, in the step of forming the base substrate 111, after mixing the main material of the EPU and the curing agent in a ratio of 10:1, the process of removing air bubbles, and the low surface energy of the EPU, the single EPU has poor adhesion. In order to solve this problem, after mixing the vinyl group and platinum, it includes a process of removing air bubbles to increase adhesion with the hard layer 112 to be formed on the upper part, and a process of pouring it on the above-described substrate RB and curing it. . In addition, it is preferable to further include a process of plasma-treating the cured base substrate 111 in order to strengthen the interfacial bond with the high hard layer 112 formed thereon, and thus formed, the Young's modulus of the base substrate 111 . Silver preferably has a range of 10 to 20 Mpa.

Next, a high hard layer 112 is patterned by printing a high hard material on the high wrinkle region FHW of the upper surface of the base substrate 111 . (See Fig. 2(b)) Here, as the high-hard material, a material having a much higher hardness than the base material is used. Therefore, it is preferable to use a material having a large Young's modulus value, for example, a Young's modulus in the range of 60 Gpa to 80 Gpa. . A representative material that can be used as a hard material is cellulose.

When the process of forming the hard layer is specifically described based on one embodiment of the present invention, the step of forming the hard layer 112 includes cellulose powder and acetic acid in purified water (DI water). ) to prepare a hard material by mixing (see FIG. 3), before printing the hydrophilic cellulose solution on the upper surface of the EPU, which is a hydrophobic surface, plasma treatment is applied to the EPU to increase the contact area of the cellulose droplets, and between EPU and cellulose The step of increasing the adhesive force of the (see FIGS. 2(a) and 2(b)), and using an inkjet printer to print the high-hard material as the binary pattern generated on the base substrate 111 is included. The hard layer thus formed preferably has a thickness of 200 to 400 nm, preferably 200 to 300 nm. The thickness of the hard layer is also closely related to wrinkles formed in the hard layer. As will be described later, wrinkles formed in the hard layer are determined by the Young's modulus ratio and thickness of the materials constituting each layer according to the formula of Buckling theory. It was found that the visibility of the pattern to be formed was greatly improved.

Referring to FIG. 2( c ), the Young's modulus is lower than that of a hard material by mixing an acrylic solution and a reinforcing material having at least any one of greater yield strength, tensile strength, impact strength, and shear strength than that of acrylic, but the refractive index is generally A similar medium hard material is impregnated on the entire upper surface of the base substrate 111 to form a medium hard layer 113 from the above-described high wrinkle region FHW to the low wrinkle region FLW adjacent to the high wrinkle region FHW. . A representative material that can be used as the reinforcing material is cellulose. That is, the reinforcing material may be the same as the high-hard material, and by using the same material as the high-hard material, the adhesion between the high-hard layer and the medium-hard layer can be increased.

When describing the process of forming the medium hard layer in detail based on one embodiment of the present invention, acrylic, which is a soft material (low hard material), is mixed with purified water and dissolved in hot water to make an aqueous acrylic solution. . After that, mixing the prepared acrylic aqueous solution with a reinforcing material (cellulose) to produce a medium-hard material having a lower Young's modulus than the high-hard material but having a substantially similar refractive index (refer to FIG. 4); Before impregnating the base substrate 111 on which the hard layer 112 is formed, plasma treatment of the base substrate 111 to increase the interfacial bonding force between the medium hard layer 113 and the high hard layer 112 and the base substrate 111 , impregnating the generated medium hard material from the high wrinkle region FHW to the low wrinkle region FLW adjacent to the high wrinkle region FHW, or impregnating the entire upper surface of the base substrate 111 . Here, the process of impregnating the medium hard material may use a spin coating method, a blade coating method, a spray coating method, or a dip coating method. The medium hard layer thus formed preferably has a thickness of 2 to 7 μm from the viewpoint of durability. Acrylic contained in the medium hard layer has strong stain resistance such as fingerprints and moisture, but plastic deformation occurs due to external stimuli and cracks are easily generated. Therefore, when the medium hard layer exceeds the thickness range, it is preferable to have the thickness range because there is a disadvantage that the acrylic content in the medium hard layer is increased and cracks are easily generated by external stimulation. Similarly, the thickness of the medium hard layer is closely related to the wrinkles formed in the medium hard layer. As will be described later, wrinkles generated in the medium hard layer are also determined by the Young's modulus ratio and thickness of the materials constituting each layer according to the formula of Buckling theory. It was found that, when applied, the visibility of the pattern displayed on the film surface was greatly improved.

Referring to FIG. 2 , as described above, a hard material is printed on the high wrinkle region FHW of the base substrate 111 created on the substrate RB to form the high hard layer 112 , and the high wrinkle region After forming the medium-hard layer 113 by impregnating the medium-wrinkled material from (FHW) to the adjacent low-wrinkled region FLW, the medium-hard layer 113 together with the high-hard layer 112 is cured to form the composite 100. produce

As in the above manufacturing method, when a composite containing a reinforcing material having at least any one of greater yield strength, tensile strength, impact strength and shear strength than acrylic and acrylic is used as a medium-hard material, durability can be improved. There is this. 5 shows that when only acrylic is used as a medium-hard material, plastic deformation occurs when an external stimulus due to bending occurs and cracks are generated in the medium-hard layer. The cracks formed in this way may cloud the surface of the variable heterogeneous surface composite, thereby weakening the durability and anti-counterfeiting function (refer to FIG. 6). On the other hand, when a composite mixed with a reinforcing material having at least one of greater yield strength, tensile strength, impact strength and shear strength than acrylic and acrylic is used as a medium-hard material, high breaking stress and It can have a strain, and at the same time, there is an advantage in that the transmittance of light can also be maintained due to the similar transmittance between the two. 7 is a variable heterogeneous surface composite 100 using a composite mixed with acrylic and cellulose as a medium hard material. Even when an external stimulus is applied, cracks do not occur in the internal material, so that the surface of the variable heterogeneous surface composite 100 is clean. indicates.

Hereinafter, the deformable heterogeneous surface composite 100 according to an embodiment of the present invention manufactured using the above-described manufacturing method will be described.

As described above, the present invention allows the wrinkled structure of the surface of the structure formed by the deformation of the load to be used as the grating structure representing the color of the structure, but is produced as a grating structure by arrangement of several wrinkles having different wavelengths according to the difference in Young's modulus A hydrophobic material capable of improving water and stain resistance while providing an active hidden-visible optical hologram that responds to pressure by allowing several grating structures to form images with different structural colors and structural colors It relates to a forgery prevention device that can be used semi-permanently by preventing contamination by fingerprints, dust, etc. through the use of a base material 111, a hard layer 112 and and a medium hard layer 113 .

The base material 111 is formed of a flexible, low-hard material, which is a soft material, so that its shape is easily deformed by an external force. At this time, the low-hard material constituting the base material 111 may be formed of any one of EPU, polyurethane, and rubber-based polymer materials. Specifically, the low-hard material is a polymer in which one or more of EPU, polyurethane, polyurea, melamine resin, and polydimethylsiloxane (PDMS) is mixed. it is preferable In addition, the base material preferably has a thickness of 200 to 300 ㎛. The base material should be easily deformed in its shape by an external force. If it has a thickness exceeding the above range, there is a disadvantage that the composite of the present invention is not easily bent when there is an external stimulus, such as a stimulus by bending, and the base If the substrate has a thickness less than the above range, there is a disadvantage that the composite of the present invention may be destroyed by an external stimulus.

The hard layer 112 is made of a hard material, which is a hard material, so that when the shape of the base material 111 is deformed, micro-sized wrinkles are formed on the surface by the difference in physical properties, and the arrangement of the wrinkles to form a grating structure by In this case, the hard material uses a material having a much higher hardness than the base material, and therefore it is preferable to use a material having a large Young's modulus value, for example, a Young's modulus in the range of 60 Gpa to 80 Gpa. A representative material that can be used as a hard material is cellulose. Meanwhile, the hard layer preferably has a thickness of 200 to 300 nm.

The medium-hard layer 113 is a medium-hard material having a lower Young's modulus than that of the high-hard material, and is formed to be slightly softer than the high-hard material. of the folds are formed, forming a grating structure by the arrangement of the folds. At this time, the medium-hard material mixes acrylic and a reinforcing material having at least one of greater yield strength, tensile strength, impact strength, and shear strength than acrylic, so that the Young's modulus is lower than that of the high-hard material, but the refractive index is generally similar. use material. A representative material that can be used as the reinforcing material is cellulose. That is, the reinforcing material included in the medium-hard material may be the same as the high-hard material, and by using the same material as the high-hard material, there is an advantage in that the adhesion between the high-hard layer and the medium-hard layer can be increased.

As described above, the high hard layer 112 and the medium hard layer 113 have a relatively high Young's modulus compared to the base material 111 , and it is preferable to have a similar refractive index. At this time, it is advantageous to form the nano-sized wrinkles or more when the difference between the Young's modulus of the base substrate 111 and the high hard layer and the medium hard layer is 100 times or more.

On the other hand, when the medium hard layer 113 has a refractive index of 96% to 104% of the high hard layer 112 or the base substrate 111, an active hidden-show structure can be implemented to react the optical hologram image according to the input. . Specifically, the two hard layers 112 and 113 do not form a grating structure according to the wrinkle arrangement in a state where no external stimulus is applied, and thus exist as a (covert) 0-dimensional lattice in which the structural color does not appear. This is because most of the incident light is transmitted through the transmissive transparency due to the same or similar refractive index (R/Cellulose - R/EPU = 0.03) of the base substrate 111 and the two hard layers 112 and 113 . Accordingly, the two hard layers 112 and 113 may be completely hidden in the base material 111 in a state where the structural color due to the grating structure formed by the wrinkle arrangement does not appear.

In addition, looking at the wrinkle formation principle for forming the grating structure in the composite of the present invention, when an external force is applied to the flexible base material and a bending load is applied in the direction of the hard layers 112 and 113, the thin and rigid hard layers 112, 113) and the hard layers 112 and 113 due to the mismatch of the mechanical properties of the base material, which is thicker and softer than the hard layers 112 and 113. Periodic width due to instability of the buckling type A wrinkle arrangement pattern having a

Here, the periodicity λ of the wrinkle arrangement is the thickness (h) of the two hard layers (112, 113), the elastic modulus (Ef) of the two hard layers (112, 113), and the base material that can be predicted through the linear buckling theory It is determined by the elastic modulus (Es) of (111) as follows.

[Equation 1]

는 평면 변형 계수이며 E/(1-v ² ) 로 정의된다. v는 포아송 비율이다. 이러한 수학식 1은 표면 주기 현상의 모델을 보여주며 가변형 이종 표면 복합체(100)의 주기성을 예측하게 한다. 세부적으로, 본 발명의 두 경질층들(112, 113)과 베이스기재(111)가 복합된 가변형 이종 표면 복합체(100)는 베이스기재(111)의 영률에 비해 두 경질층들(112, 113)의 영률이 매우 높기 때문에 두 경질층(112, 113)을 강성을 가진 필름층으로 간주할 수 있으며, 주름의 각 파장의 크기(폭)는 두 경질층들(112, 113)과 베이스기재(111)의 영률(E)의 상대적인 차이와 두께(h)의 상대적인 차이에 따라 결정된다.here,

is the plane strain coefficient and is defined as E/(1-v ² ) . v is the Poisson ratio. Equation 1 shows a model of the surface periodicity phenomenon and predicts the periodicity of the variable heterogeneous surface composite 100 . In detail, the variable heterogeneous surface composite 100 in which the two hard layers 112 and 113 and the base substrate 111 of the present invention are combined is compared to the Young's modulus of the base substrate 111 by the two hard layers 112 and 113. Since the Young's modulus of is very high, the two hard layers 112 and 113 can be regarded as film layers having rigidity, and the size (width) of each wavelength of the wrinkle is different from the two hard layers 112 and 113 and the base substrate 111. ) is determined according to the relative difference in Young's modulus (E) and the relative difference in thickness (h).

Here, since there is a relative difference between the Young's modulus (E) and the thickness (h) of the base substrate, the high hard layer, and the medium hard layer, the wrinkle arrangement patterns are formed differently. Due to the above difference, the wrinkled structure (micro unit) formed in the high wrinkled region (FHW) where the high hard layer 112 is formed and the wrinkled structure (nano) formed in the low wrinkled region FLW where the medium hard layer 113 is formed unit) is changed, and thus the saturation of the structural color and the image displayed are different.

100: variable heterogeneous surface composite 111: base substrate 112: high hard layer
113: medium hard layer FHW: high wrinkle region FMW: low wrinkle region

Claims (10)

Forming a base substrate formed of a flexible low-hard material and including a high wrinkled region and a low wrinkled region adjacent to the high wrinkled region;
forming a high hard layer formed in a pattern on the high wrinkle area and made of a high hard material having a larger Young's modulus than the low hard material;
Covers the low wrinkle region and the high hard layer, has a Young's modulus larger than the low hard material and smaller than the high hard material, and at least one of yield strength, tensile strength, impact strength and shear strength is more than acrylic and acrylic forming a medium-hard layer formed of a medium-hard material including a large reinforcing material;
curing the high hard layer and the medium hard layer
A method for producing a variable heterogeneous surface composite comprising a.
According to claim 1,
Plasma treatment on the base material before forming the hard layer so as to increase the bonding force between the base material and the hard layer;
Plasma treatment before forming the medium hard layer so that the medium hard layer has a higher bonding strength with the base substrate and the high hard layer;
A method for manufacturing a tunable heterogeneous surface composite.
According to claim 1,
The step of forming the hard layer,
A method for producing a variable heterogeneous surface composite, characterized in that a high-hard layer is formed using a polymer material of cellulose.
4. The method of claim 3,
The step of forming the medium hard layer,
Forming a medium hard layer using acrylic and a reinforcing material,
The reinforcing material is characterized in that the same as the high-hard material,
A method for manufacturing a tunable heterogeneous surface composite.
5. The method of claim 4,
The medium-hard material constituting the medium-hard layer is a variable type heterogeneous surface composite manufacturing method, characterized in that it is a composite in which acrylic and reinforcing material are mixed.
According to claim 1,
In the step of forming the base substrate, the base substrate has a thickness of 200 to 300 μm,
In the step of forming the hard layer, the hard layer has a thickness of 200 to 400 nm,
In the forming of the medium hard layer, the method for manufacturing a variable heterogeneous surface composite, characterized in that the medium hard layer has a thickness of 2 to 7 μm.
According to claim 1,
The deformable heterogeneous surface composite is corrugated by a single load of any one of compression, tension, bending, and torsion, or a combined load of two or more, and forms a grating structure due to the corrugation,
In the step of forming the hard layer, if the grating structure is not formed, the hard layer has the same or similar color as that of the base material and is hidden in the color of the base material. Forming to have a refractive index of 96% to 104%,
In the step of forming the medium hard layer, if the grating structure is not formed, the medium hard layer has the same or similar color as the base material and is hidden in the color of the base material, 96% of the base material to A method for producing a variable heterogeneous surface composite comprising the step of forming to have a refractive index of 104%.
According to claim 1,
The base material, EPU, polyurethane (Polyurethane) and a method of manufacturing a variable heterogeneous surface composite, characterized in that formed of any one of a rubber-based polymer material.
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