Biomimetic polymer multilayer structure with metallic feel and method for manufacturing the same

Abstract

The present invention relates to a metallic polymer multilayer structure having a structure in which polymer layers each containing two or more different polymers with a refractive index difference of 0.3 or more are alternately laminated, each polymer layer independently having a thickness within a range of 95 to 195 nm, and at least one of the polymer layers contains guanine as a plate-like pigment, and a method for producing the same.

Description

[Technical Field]

[0001] The present invention relates to a polymeric material with a metallic appearance that exhibits metallic color, luster, texture, etc., and a method for producing the same. [Background technology]

[0002] Although polymer materials such as plastics have advantages such as excellent functionality, moldability, light weight, and low cost, they are generally perceived as cheap materials because they are inferior in terms of color, texture, and sensitivity when perceived from the appearance of the material compared to other materials such as ceramics and metals.

[0003] Therefore, interest in surface decoration technology is gradually increasing as a means of improving the color, texture, and aesthetics of polymer materials. In recent years, such surface decoration technology for polymer materials has expanded beyond the original purpose of improving appearance and appearance to include "functional decoration" that imparts electrical and optical functions, antibacterial functions, electrostatic functions, virus resistance, and surface tactile functions, etc., and there is a growing need for dry methods of decoration instead of wet methods such as painting.

[0004] Furthermore, polymer multilayer structures obtained by dispersing heterogeneous materials such as metals and ceramics in polymers have the advantage of not only improving the color, texture, and aesthetics of polymer materials, but also realizing a variety of functions that cannot be achieved with materials consisting of polymers alone.

[0005] Meanwhile, product design requirements have recently become more diverse across all industries, including the automotive industry, with product selection criteria evolving from performance requirements such as product price and functionality to factors such as aesthetics, high quality, and convenience. This shift in trends has led to an increase in the use of metallic-textured parts in automotive interiors. While plating and painting methods are the most commonly used methods to achieve a metallic texture, environmental concerns have led to a steady increase in research into metallic composite materials that can achieve a metallic texture through a single part injection process. Summary of the Invention [Problem to be solved by the invention]

[0006] The technical problem to be solved by the present invention is to provide a polymeric multilayer structure having a metallic appearance, such as a metallic color, luster, texture, etc., and a method for producing the same. [Means for solving the problem]

[0007] In order to solve the above technical problems, the present invention proposes a metallic polymer multilayer structure having a structure in which polymer layers containing two or more different polymers with a refractive index difference of 0.3 or more are alternately laminated, each polymer layer independently having a thickness within the range of 95 to 195 nm, and at least one polymer layer contains guanine as a plate-like pigment.

[0008] The present invention also proposes a metallic polymer multilayer structure, characterized in that the refractive index difference between the polymer contained in the guanine-containing polymer layer and the guanine among the polymer layers constituting the metallic polymer multilayer structure is 0.3 or more.

[0009] The present invention also proposes a metallic polymer multilayer structure, characterized in that each of the two or more different polymers is (i) a thermoplastic resin selected from acrylic resins, olefin resins, vinyl resins, styrene resins, fluorine resins, and cellulose resins, or (ii) a thermosetting resin selected from phenolic resins, epoxy resins, and polyimide resins.

[0010] In addition, the present invention proposes a metallic polymer multilayer structure, wherein one or more polymer layers contained in the metallic polymer multilayer structure contain one or more plate-like nanoparticles selected from the group consisting of montmorillonite (MMT), pyrophyllite-talc, fluorohectorite, kaolinite, vermiculite, illite, and mica.

[0011] In addition, from another aspect of the invention, the present invention proposes, as one embodiment of the method for producing a metallic polymer multilayer structure, a method for producing a metallic polymer multilayer structure, comprising the steps of: (a) producing film-like molded bodies each containing two or more different polymers having a refractive index difference of 0.3 or more, at least one of which contains guanine as a plate-like pigment; (b) stretching each of the molded bodies produced in step (a) to produce a film having a thickness in the range of 95 to 195 nm; and (c) alternately stacking the films produced in step (b) to produce a multilayer structure. [Effects of the Invention]

[0012] The method for manufacturing a polymer multilayer structure with a metallic finish according to the present invention solves the problems of poor adhesion between the metal thin film and the polymer surface, and the corrosiveness and toxicity of some metal particles, which arise in conventional techniques for plating or painting metal particles on the surface of polymer materials such as plastics to impart a metallic finish to polymer materials. Furthermore, it can realize a polymer-based material with a metallic finish that has a reflectance of 80% or more in the visible light wavelength range (380 to 780 nm). Therefore, it can be useful for manufacturing materials that can be widely used in various fields where aesthetics are required, such as automotive interior materials, home appliances, and cosmetic packaging. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a cross-sectional view showing an example of a metallic polymer multilayer structure according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] In describing the present invention, if it is determined that a detailed description of related publicly known functions or configurations may unnecessarily obscure the gist of the present invention, the detailed description will be omitted.

[0015] Since the embodiments according to the concept of the present invention can be variously modified and can have various forms, specific embodiments are illustrated in the drawings and will be described in detail in this specification or application, but it is not intended to limit the embodiments according to the concept of the present invention to the specific disclosed forms, and it should be understood that all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention are included.

[0016] The terms used in this specification are merely used to describe specific embodiments and are not intended to limit the present invention. The singular expressions include the plural expressions unless the context clearly indicates otherwise. In this specification, the terms "comprise" or "have" are intended to specify the presence of the stated features, numbers, steps, operations, components, parts, or combinations thereof, and should be understood not to preclude the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0017] Optical thin films can change the spectral properties of optical surfaces, such as reflectance, transmittance, absorptance, polarization, phase, and color, to suit specific purposes by utilizing the optical properties of the medium and the effects of light interference. Designed by determining the refractive index, thickness, and number of layers of the material, optical thin films come in a variety of coatings, including AR coating (anti-refection coating), HR coating (high reflection coating), short wave pass, and long wave pass, with anti-reflective coatings used on eyeglasses being a typical example.

[0018] The optical properties of a material are expressed by the optical constant N, which is the complex refractive index, and is expressed as follows via the refractive index and the extinction coefficient k:

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[0019] Optical admittance is a physical quantity that plays a very important role in the design, deposition, and characterization of optical thin films, and is defined as the ratio of the magnetic field to the electric field. When a plane wave with angular frequency ω and propagation vector K propagates in a homogeneous and isotropic medium, the electric field and the magnetic field are respectively

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[0020] Distributed Bragg reflectors (DBRs) are multilayer mirrors made of two materials with different refractive indices, typically 5 to 50 periods. Due to the difference in refractive indices, Fresnel reflection occurs at each interface. Since the difference in refractive indices between the two materials is usually small, the degree of Fresnel reflection at a single interface is very small. However, many DBRs are made up of many interfaces, and the thickness of the two materials must be selected so that all reflected waves can undergo constructive interference. Alternatively, if the difference in refractive indices between the two materials is large enough to increase the constructive interference effect at a single interface, a reflectivity close to 1 can be achieved. This condition is met when the thickness of the two materials is 1 / 4 the wavelength of light for normal incidence. For normal incidence, the following holds:

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[0021] The thickness given by the formula can be not only λ / 4, but also odd integer multiples such as λ / 4, 3λ / 4, 5λ / 4, 7λ / 4, etc. These thicknesses will cause constructive interference of the reflected waves. However, for layer thicknesses greater than λ / 4, such as 3λ / 4, the high reflectivity cutoff band becomes narrower. For oblique angles of incidence, the wave vector can be separated into horizontal and vertical components.

[0022] For oblique incidence, as for normal incidence, the thickness of the DBR layer must be 1 / 4 wavelength for the wave vector component normal to the DBR layer. The optimum thickness for high reflectivity for an oblique incidence angle θ is given by:

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[0023] As with normal incidence, for a given thickness T l,hmay be an odd integer multiple of the given value.

[0024] Guanine crystals are widely used in nature to manipulate light. The reason guanine crystals appear silvery in nature is because they exhibit high reflectivity over a wide bandwidth. The high reflectivity of natural optical systems made of guanine comes from the fact that they have a very high refractive index (n = 1.83). To optimize reflectivity, the high refractive index surfaces of guanine form plate-like single crystals in most organisms. The guanine present in hairtail scales also has the ability to modulate the reflection of incident light, resulting in a silvery or metallic appearance.

[0025] In addition, guanine has optical anisotropy. However, the high refractive index of guanine occurs along the crystal axis corresponding to the stacking direction of the guanine molecules, while the refractive index in the perpendicular direction is estimated to be much lower, at about n = 1.45. In other words, the refractive index clearly differs depending on the stacking direction of the guanine molecules. Therefore, if the orientation is varied based on the crystal axis of guanine, the refractive index will show a variety of distributions in the range of 1.45 to 1.83.

[0026] Applying this, when the refractive index of the polymer matrix is ​​about 1.4 and the refractive index of guanine is 1.45, the difference in refractive index is small, resulting in low reflectivity, but when the refractive index of guanine is 1.83, the difference in refractive index is large, resulting in high reflectivity. Therefore, the refractive index can be adjusted by controlling the degree of orientation using the anisotropy of guanine crystals, thereby controlling the reflectivity.

[0027] Based on the above-mentioned principle, the present invention proposes a multilayer polymer structure consisting of a structure in which multiple polymer layers containing two or more different polymers whose refractive index difference is a specific value (0.3) or more are alternately stacked, and in order to biomimetically mimic the silvery luster that appears on the surface of hairtail due to the plate-like guanine contained in the skin layer of the hairtail, at least one of the polymer layers contains guanine as a plate-like pigment.

[0028] In this case, it is more preferable that the difference in refractive index between the polymer contained in the guanine-containing polymer layer and the guanine among the polymer layers constituting the metallic polymer multilayer structure is 0.3 or more.

[0029] Furthermore, the present invention proposes a metallic polymer multilayer structure in which each polymer layer constituting the metallic polymer multilayer structure has an optical thickness of 1 / 4 of the wavelength of visible light, i.e., in the range of 95 to 195 nm, independently of other polymer layers such as adjacent polymer layers.

[0030] That is, the metallic polymer multilayer structure according to the present invention has regularity in that polymer layers containing different polymers are alternately laminated, but the thickness of each polymer layer has an arbitrary value within a certain range (95 to 195 nm) independently of the thickness of the other polymer layers, and therefore the thickness of the polymer layers has a random arrangement without forming a gradient in the thickness direction of the polymer multilayer structure.

[0031] 1 is a cross-sectional view showing an example of a metallic polymer multilayer structure according to the present invention. Referring to FIG. 1, polymer layers P11, P12, ... P11 are made of a first polymer P1. n-1 , P1 n and polymer layers P21, P22, ... P2 made of a second polymer P2. n-1 , P2 nThe polymer multilayer structure has a structure in which the polymers are arranged alternately, while guanine is dispersed disorderly as a plate-like pigment within some of the polymer layers, and each polymer layer has an arbitrary thickness within the range of 95 to 195 nm, independently of the others, and exhibits a random thickness arrangement.

[0032] Meanwhile, the method for producing a polymer multilayer structure according to the present invention is not particularly limited, and as an example, it may include the steps of: (a) producing two or more film-shaped first polymer-containing molded bodies containing a first polymer (such as polyvinyl alcohol (PVA)) and two or more film-shaped second polymer-containing molded bodies containing a second polymer (such as triacetyl cellulose (TAC)); (b) stretching the first polymer-containing molded body and the second polymer-containing molded body, respectively, to produce a first polymer-containing film and a second polymer-containing film having any thickness within the range of 95 to 195 nm; and (c) alternately laminating the first polymer-containing film and the second polymer-containing film to produce a multilayer structure.

[0033] The two or more different polymers contained in each polymer layer of the metallic polymer multilayer structure according to the present invention are each made of a thermoplastic resin or a thermosetting resin.

[0034] More specifically, examples of the thermoplastic resin include olefin-based resins such as polyethylene, polypropylene, and poly-4-methylpentene-1; acrylic resins such as polymethyl methacrylate and acrylonitrile; vinyl resins such as polyvinyl chloride, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, and polyvinylidene chloride; styrene-based resins such as polystyrene and ABS resin; fluororesins such as tetrafluoroethylene resin, trifluoroethylene resin, polyvinylidene fluoride, and polyvinyl fluoride; and cellulose-based resins such as nitrocellulose, cellulose acetate, ethyl cellulose, and propylene cellulose. In addition to these, polyamide, polyamideimide, polyacetal, polycarbonate, polyethylene butyrate, polybutylene butyrate, ionomer resin, polysulfone, polyethersulfone, polyphenylene ether, polyphenylene sulfide, polyetherimide, polyetheretherketone, and aromatic polyesters (econol and polyarylate) can also be used.

[0035] Examples of the thermosetting resin include phenol resin, epoxy resin, and polyimide resin.

[0036] In addition, in order to increase and / or improve the optical properties, such as the reflectance, of the metallic polymer multilayer structure according to the present invention, one or more polymer layers included in the multilayer structure may contain one or more plate-like nanoparticles selected from the group consisting of montmorillonite (MMT), pyrophyllite-talc, fluorohectorite, kaolinite, vermiculite, illite, and mica.

[0037] In one embodiment of the metallic polymer multilayer structure containing guanine according to the present invention, the polymer in each layer is manufactured by alternating lamination of a high refractive index polymer and a low refractive index polymer. The difference in refractive index between the high refractive index polymer and the low refractive index polymer is 0.3 or more, and in this case, the plate-like pigment is contained in the low refractive index material layer. The number of polymer films laminated in the multilayer structure is 257, and the content of the plate-like pigment contained in the low refractive index material layer is 0.1 to 10 wt%. For example, when a nanostructure is formed by laminating a melamine film and a Teflon film, the melamine film is the high refractive index material and the Teflon film is the low refractive index material. In this case, guanine, a high refractive index plate-like pigment, is added when manufacturing the Teflon film, which is a low refractive index material.

[0038] The metallic polymer multilayer structure according to the present invention solves the problems of poor adhesion between the metal thin film and the polymer surface, and the corrosiveness and toxicity of some metal particles, which arise in conventional techniques for plating or painting metal particles on the surface of polymer materials such as plastics to impart a metallic look to polymer materials. Furthermore, it can realize a metallic polymer-based material with a reflectance of 80% or more in the visible light wavelength range (380 to 780 nm), and can therefore be useful in various fields where aesthetic appeal is required, such as automotive interior materials, home appliances, and cosmetic packaging.

[0039] Although the embodiments of the present invention have been described above with reference to the accompanying drawings, those skilled in the art will understand that the present invention can be embodied in other specific forms without changing the technical spirit or essential characteristics of the present invention. Therefore, it should be understood that the above-described embodiments are illustrative in all respects and are not limiting. [Industrial Applicability]

[0040] The method for producing a metallic polymer multilayer structure according to the present invention can produce a metallic polymer-based material having a reflectance of 80% or more in the visible light wavelength range (380 to 780 nm), and therefore can be useful for producing materials that can be widely used in various fields where aesthetics are required, such as automotive interior materials, home appliances, and cosmetic packaging.

Claims

1. It has a structure in which polymer layers each containing two or more different polymers having a refractive index difference of 0.3 or more are alternately laminated, each polymer layer independently having a thickness ranging from 95 to 195 nm; At least one of the polymer layers contains guanine as a platelet pigment; A metallic polymer multilayer structure, characterized in that the refractive index of guanine is 1.45 to 1.83, and the difference in refractive index between the polymer contained in the guanine-containing polymer layer and the guanine is 0.3 or more.

2. Each of the two or more different polymers is 2. The metallic polymer multilayer structure according to claim 1, characterized in that the resin is (i) a thermoplastic resin selected from acrylic resins, olefin resins, vinyl resins, styrene resins, and fluorine resins, or (ii) a thermosetting resin selected from phenolic resins, epoxy resins, and polyimide resins.

3. One or more polymeric layers 10. The metallic polymer multilayer structure according to claim 1, comprising one or more plate-like nanoparticles selected from the group consisting of montmorillonite (MMT), pyrophyllite-talc, fluorohectorite, kaolinite, vermiculite, illite, and mica.

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