Patent Publication Number: US-2020298615-A1

Title: Optical decorative film, manufacturing method, and cover plate for consumer electronics

Description:
TECHNICAL FIELD 
     The present invention relates to the field of optics, and in particular to an optical decorative film, a manufacturing method and a cover plate for consumer electronics. 
     BACKGROUND 
     Currently, with the ever progressing development in consumer electronic industries, manufacturers are constantly seeking innovations in technology and functions to keep up with the trend of advances in environmental protection, energy saving, and differentiation development. Designs of consumer electronics are no longer limited to improvement in functions, and many designers are now focusing on the exterior designs of consumer electronics. In the case of cell phones, a cover plate for a cell phone not only protects the parts inside the phone but also beautifies and decorates the phone. A design for a cell-phone cover plate having an excellent decorative effect may not only add value to the cell phone but also improve the experience of a user and broaden the range of choices of cell phone appearances for the user, making the cell phone more popular among users. 
     However, the decorative designs for a cell-phone cover plate are now focused on alteration in material (e.g., glass, metal, plastic) or changing a single color of the printing ink layer, which results in a monotonous visual effect and therefore an unsatisfactory, less distinctive decoration. 
     SUMMARY OF THE INVENTION 
     In this regard, it is necessary to provide an optical decorative film to solve the above technical problems. 
     A technical solution according to the present invention is: 
     an optical decorative film, comprising:
         a support layer having a first side and an opposite second side;   an optical layer provided on the first side and having a plurality of micro-nano structures in a convex and/or concave arrangement; and   a decorative layer provided on the second side and supported by the support layer.       

     In one embodiment, the decorative layer includes a reflective layer overlying the second side and a colored layer overlying the reflective layer. 
     In one embodiment, a protective layer overlying the optical layer for protecting the micro-nano structures is further provided, and the difference in refractive index between the protective layer and the micro-nano structures is greater than or equal to 0.01. 
     In one embodiment, the support layer includes a glass layer, a PET layer, a PC layer, or a PMMA layer. 
     In one embodiment, the transmittance of the support layer and the optical layer is greater than or equal to 10%, or the transmittance of the support layer and the decorative layer is greater than or equal to 10%. 
     In one embodiment, the decorative layer includes one layer of a texture layer, a graphic layer, or a colorful layer, or superimposed layers of two or more thereof, wherein the texture layer comprises a plurality of texture structures in a convex and/or concave arrangement. 
     In one embodiment, the decorative layer includes a composite layer of colorful texture layers or colorful graphic layers, wherein the texture layer comprises a plurality of texture structures in a convex and/or concave arrangement. 
     In one embodiment, the micro-nano structures are one or more of linear cylindrical lens, curved cylindrical lens, micro lens, Fresnel lens, CD patterns, short lines, moth-eye structures, and brushed patterns, with or without spacing provided between the micro-nano structures; the texture structures are one or more of linear cylindrical lens, curved cylindrical lens, micro lens, Fresnel lens, CD patterns, short lines, moth-eye structures, brushed patterns, with or without spacing provided between the texture structures. 
     In one embodiment, the decorative layer includes a texture layer, and there is no interference between the micro-nano structures and the texture structures. 
     In one embodiment, the micro-nano structures have a gradient arrangement, and/or the texture structures have a gradient arrangement. 
     In one embodiment, the graphic layer comprises a UV resin with grooves and a filler filled inside the grooves, and the filler forms the graphic of the graphic layer. 
     In one embodiment, the colorful layer has a gradient color. 
     In one embodiment, the colorful layer comprises a UV resin layer with gradient grooves and a colorful material filled inside the grooves, and the colorful layer presents a gradient color. 
     In one embodiment, the support layer is a PET layer having a thickness larger than that of the decorative layer. 
     In one embodiment, the optical decorative film has a colored layer, a reflective layer, an optical layer, a support layer, and a decorative layer stacked in this order. 
     In one embodiment, a colorful layer and/or a graphic layer is further provided between the optical layer and the support layer. 
     In one embodiment, the decorative layer is stacked with a colorful layer and a texture layer in this order; or the decorative layer is stacked with a graphic layer and a texture layer in this order; or the decorative layer is stacked with a colorful layer and a graphic layer in this order; or the decorative layer comprises a colorful layer, a graphic layer, and a texture layer. 
     In one embodiment, the decorative layer further comprises a binding layer that binds the decorative layer to the second side of the support layer. 
     In one embodiment, the colorful layer is a gradient color layer, and/or the texture structures of the texture layer are in a gradient arrangement. 
     In one embodiment, the decorative layer at least includes two or more colorful layers, and/or the decorative layer at least includes two or more graphic layers, and/or the decorative layer at least includes two or more texture layers. 
     The present invention further discloses a cover plate for consumer electronics, comprising the optical decorative film as described above. 
     The present invention further discloses a manufacturing method for an optical decorative film, which method comprises:
         applying a polymer on a first side of a support layer, and forming a plurality of micro-nano structures on the polymer;   binding a decorative layer through a binding layer thereof to a second side of the support layer.       

     An alternative manufacturing method for an optical decorative film comprises:
         applying a polymer on a first side of a support layer, and forming a plurality of micro-nano structures on the polymer;   forming a decorative layer on a second side of the support layer.       

     In one embodiment, the second side of the support layer is coated with a polymer, and a plurality of texture structures are formed on the polymer; or the second side of the support layer is coated with a polymer, and a plurality of grooves are formed on the polymer, and then filled with materials to form a graphic layer; or the second side of the support layer is coated with a polymer, and a plurality of grooves are formed on the polymer and then filled with materials to form a colorful layer. 
     In one embodiment, the first side of the support layer is implemented first; or the second side of the support layer is implemented first; or the first and second sides of the support layer are simultaneously implemented. 
     The present invention has the following advantageous effects: an optical layer and a decorative layer are respectively provided on a first side and a second side of a support layer, which produces a dual decorative effect and is highly distinctive, with only one support layer to realize a relatively small thickness. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view of a structure of the optical decorative film according to the present invention; 
         FIG. 2  is a schematic view of another structure of the optical decorative film according to the present invention; 
         FIG. 3  is a schematic view of another structure of the optical decorative film according to the present invention; 
         FIG. 4  is a schematic view of another structure of the optical decorative film according to the present invention; 
         FIG. 5  is a schematic view of another structure of the optical decorative film according to the present invention; 
         FIG. 6  is a schematic view of another structure of the optical decorative film according to the present invention; 
         FIG. 7  is a schematic view of another structure of the optical decorative film according to the present invention; 
         FIG. 8  is a schematic view of another structure of the optical decorative film according to the present invention; 
         FIG. 9  is a schematic view of another structure of the optical decorative film according to the present invention; 
         FIG. 10  is a schematic view of another structure of the optical decorative film according to the present invention; 
         FIG. 11  is a schematic view of another structure of the optical decorative film according to the present invention; 
         FIG. 12  is a schematic view of a structure of a cover plate for consumer electronics according to the present invention; 
         FIG. 13  is a flowchart of a manufacturing process for the optical decorative film according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     For a better understanding of the present invention, more detailed description of the present invention will now be provided below with reference to the accompanying drawings. In the drawings, preferred embodiments of the invention are illustrated. However, the present invention can be implemented in many different forms and is not limited to the embodiments described below. On the contrary, these embodiments are given in order to provide a more thorough and complete understanding of the disclosure of the present invention. 
     Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by a person skilled in the art to which this invention belongs. The terms used herein in the description of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The term “and/or” as used herein includes any and all combinations of one or more of relevant items listed. 
     The present invention discloses an optical decorative film which comprises a support layer, an optical layer, and a decorative layer. The support layer includes a first side and an opposite second side. The optical layer is formed on the first side, and includes a plurality of micro-nano structures in a convex and/or concave arrangement. The decorative layer is provided on the second side and is supported by the support layer. The first side and the second side of the support layer are respectively provided with an optical layer and a decorative layer, which produces a duel decorative effect and is highly distinctive, with only one support layer to realize a relatively small thickness. 
     The decorative layer is provided on the second side and is supported by a support layer. Both the optical layer and the decorative layer are supported by a support layer, and share the same support layer. The support layer has a certain thickness and hardness, and is for example PET, glass etc., to facilitate forming of the optical layer and the decorative layer, and to play a role of supporting. Structures are provided on both sides of the support layer to maximize the decorative effect and reduce the overall thickness of the optical decorative film. 
     Preferably, the decorative layer includes a reflective layer overlying the second side and a colored layer overlying the reflective layer. The optical layer is disposed on the first side of the support layer, and the reflective layer and the colored layer are disposed on the second side of the support layer. The process is simple and the decorative effect is excellent. As compared to the case they are separately formed on a support layer and then stacked, the thickness is reduced. 
     Preferably, the decorative optical film further includes a protective layer overlying the optical layer for protecting the micro-nano structures, and the difference in refractive index between the protective layer and the micro-nano structures is greater than or equal to 0.01, thereby ensuring the optical characteristics of the micro-nano structures. 
     Preferably, the support layer includes a glass layer, a PET layer, a PC layer, or a PMMA layer. That is, the support layer of the decorative optical film has a single-layer structure, and an optical layer and a decorative layer are respectively provided on both sides of the support layer, thereby enhancing the decorative effect and reducing the overall thickness of the decorative optical film. 
     Preferably, in order to ensure the visual effect, it is necessary to have a transmittance of the support layer and the optical layer of 10% or more, or a transmittance of the support layer and the decorative layer of 10% or more. 
     Preferably, the decorative layer includes one layer of a texture layer, a graphic layer, or a colorful layer, or superimposed layers of two or more thereof. Alternatively, the decorative layer includes a composite layer of a colorful texture layer or a colorful graphic layer. The texture layer includes a plurality of texture structures in a convex and/or concave arrangement. The superimposed layers are vertically stacked two or more layers, for example, a colorful layer and a texture layer provided on the colorful layer. A composite layer is that two layers shares a fused and overlapping part, e.g., the UV resin forming a texture layer is colored itself. 
     Preferably, the micro-nano structures are one or more of linear cylindrical lens, curved cylindrical lens, micro lens, Fresnel lens, CD patterns, short lines, moth-eye structures, brushed patterns, with or without spacing provided between the micro-nano structures. The texture structures are one or more of linear cylindrical lens, curved cylindrical lens, micro lens, Fresnel lens, CD patterns, short lines, moth-eye structures, brushed patterns, with or without spacing provided between the texture structures. The micro-nano structures and the texture structures are not associated with each other and do not interfere with each other, that is, they are independently provided. 
     Preferably, the micro-nano structures are in a gradient arrangement. For example, the micro-nano structures are cylindrical lens with their width gradually decreasing in one direction of arrangement. 
     Preferably, the texture structures are in a gradient arrangement. For example, the texture structures have a cross section in the form of grooves with their width increasing along one direction of arrangement. 
     Preferably, the graphic layer includes a UV resin with grooves and a filler filled inside the grooves, and the filler forms the graphic of the graphic layer. The graphic is not within the focal length of the micro-nano structures, that is, the graphics and the micro-nano structures do not adapt to form an image. 
     Preferably, the colorful layer has a gradient color. For example, the colorful layer includes a UV resin layer with gradient grooves and a colorful material filled inside the grooves. The colorful material per unit area is disposed in a gradient such that the colorful layer presents a gradient color. 
     Preferably, the support layer is a PET layer, and the thickness of the PET layer is greater than that of the decorative layer. Because the decorative layer is directly formed on the PET layer, or the decorative layer is first formed on another substrate and then bonded to the PET layer after the substrate is separated, the decorative layer may be regarded as free of substrate, which means the decorative layer has an overall thickness less than that of the PET layer. By forming a decorative layer on the other side of the PET layer according to the present invention, the decorative effect is further enhanced, while the thickness of the entire decorative optical film is still controlled and is greatly reduced as compared to that of simply stacked decorative PET films, which meets the requirements of the market development. 
     Preferably, the optical decorative film has a colored layer, a reflective layer, an optical layer, a support layer, and a decorative layer stacked in this order. In other embodiments, a colorful layer and/or a graphic layer may certainly be further included between the optical layer and the support layer. 
     Preferably, the decorative layer is stacked with a colorful layer and a texture layer in this order; or the decorative layer is stacked with a graphic layer and a texture layer in this order; or the decorative layer is stacked with a colorful layer and a graphic layer in this order; or the decorative layer comprises a colorful layer, a graphic layer, and a texture layer. 
     Preferably, the decorative layer further comprises a binding layer that binds the decorative layer to the second side of the support layer. 
     Preferably, the colorful layer is a gradient color layer. In a predetermined direction, the color gradually lightens or darkens. For example, the color gradually lightens from top to bottom; or the color gradually lightens from both sides inward. 
     Preferably, the texture structures of the texture layer are in a gradient arrangement. In a predetermined direction, the duty ratio per unit area is set in a gradient. 
     Preferably, the decorative layer may include at least two or more colorful layers. 
     Preferably, the decorative layer may include at least two or more graphic layers. 
     Preferably, the decorative layer may include at least two or more texture layers. 
     The invention also discloses a cover plate for consumer electronics that comprises the optical decorative film as described above, for example, a cover plate for cell phones. A cell-phone cover plate with the optical decorative film has a better decorative effect and is highly noticeable, and despite having both an optical layer and a decorative layer, it has only one support layer, which does not increase the thickness of the cell-phone cover plate and meets the trend of development in the market in terms of lightness and thinness. 
     The invention also discloses a manufacturing method for an optical decorative film, comprising the following steps: 
     Step 1, coating a first side of the support layer with a polymer, preferably a UV resin, and then forming a plurality of micro-nano structures on the UV resin; 
     Step 2, bonding the decorative layer to the second side of the support layer via a polymer layer of the decorative layer. 
     Step 1 may be performed first, and then step 2; alternatively, step 2 may be performed first, and then step 1; or both steps 1 and 2 may be performed simultaneously. 
     Step 1 may further include vapor depositing a reflective layer on the plurality of micro-nano structures, and applying a colored layer (preferably an ink priming layer) on the reflective layer. 
     An alternative manufacturing method for an optical decorative film according to the present invention includes the following steps: 
     Step 1, applying a polymer (preferably a UV resin) on the first side of the support layer, and forming a plurality of micro-nano structures on the polymer; 
     Step 2, forming a decorative layer on the second side of the support layer. 
     Step 1 may be performed first, and then step 2; alternatively, step 2 may be performed first, and then step 1; or both step 1 and step 2 may be performed simultaneously. 
     Step 1 may further include vapor depositing a reflective layer on the plurality of micro-nano structures, and applying a colored layer (preferably an ink priming layer) on the reflective layer. 
     In step 2, more specifically, the second side of the support layer is coated with a polymer (preferably a UV resin) and a plurality of texture structures are formed on the polymer. Alternatively, the second side of the support layer is coated with a polymer (preferably a UV resin), a plurality of grooves are formed on the polymer and the grooves are filled with materials to form a graphic layer. Alternatively, the second side of the support layer is coated with a polymer (preferably a UV resin), a plurality of grooves is formed on the polymer and the grooves are filled with materials (colorful materials) to form a colorful layer. 
     The embodiments of the present invention will be described hereinafter in more details with reference to the drawings. 
     Referring to  FIG. 1 , an optical decorative film  100   a  includes a support layer  1   a , an optical layer  21   a , and a decorative layer  3   a . The support layer  1   a  includes a first side  11   a  and an opposite second side  12   a . The optical layer  21   a  is disposed on the first side  11   a , and the optical layer  21   a  includes a plurality of micro-nano structures  211   a  in a convex arrangement. The decorative layer  3   a  is disposed on the second side  12   a  and is supported by the support layer  1   a . Preferably, the micro-nano structures  211   a  are curved cylindrical lens. The optical decorative film  100   a  further includes a reflective layer  22   a  overlying the optical layer  21   a  and a colored layer  23   a  overlying the reflective layer  22   a . The decorative layer  3   a  includes a texture layer  31   a  formed on the second side  12   a  and a protective layer  32   a  overlying the texture layer  31   a . The texture layer  31   a  includes a plurality of texture structures  311   a  in a convex arrangement. The texture structures  311   a  are curved cylindrical lens. The micro-nano structures  211   a  are spaced from each other on the first side  11   a , and the texture structures  311   a  are spaced from each other on the second side  12   a . On a projection plane parallel to the first side  11   a , the micro-nano structures  211   a  and the texture structures  311   a  are staggering with each other and do not completely overlap. The optical layer  21   a  may present bright light-and-shadow streaks, while the texture layer  31   a  may present another type of bright light-and-shadow streaks, and the two types of bright light-and-shadow streaks may be present independently and do not interfere with each other. The optical layer  21   a  and the decorative layer  3   a  are respectively disposed on the first side  11   a  and the second side  12   a  of the support layer  1   a , which brings about a duel decoration effect and is highly distinctive, and the thickness of the optical decorative film is greatly reduced in comparison to the case where the optical layer and the decorative layer each requires a support layer. 
     Now referring to  FIG. 13 , a manufacturing method for the optical decorative film  100   a  includes the following steps: 
     step S1, applying a UV resin on the first side  11   a  of a support layer  1   a , and embossing a plurality of micro-nano structures  211   a , followed by curing to form an optical layer  21   a;    
     step S2, vapor depositing a reflective layer  22   a  on the optical layer  21   a , and applying ink on the reflective layer  22   a  to form a colored layer  23   a;    
     step S3, applying a UV resin on the second side  12   a  of the support layer  1   a , and embossing a plurality of texture structures  311   a , followed by curing to form a texture layer  31   a;    
     step S4, applying a protective polymer on the texture layer  31   a  to form a protective layer  32   a.    
     On the first side  11   a  and the second side  12   a  of a support layer  1   a  are provided with an optical layer  21   a  and a texture layer  31   a , respectively, which brings about a duel decorative effect and a small overall thickness. 
     In other examples, steps S3 and S4 may be performed before steps S1 and S2. 
     In other examples, step S1 and step S3 are performed simultaneously. 
     The reflective layer  22   a  is made of a material having a reflective effect, such as metal or nonmetal, and the colored layer  23   a  is a priming ink layer. The transmittance of the support layer  1   a  and the decorative layer  3   a  is 10% or more, preferably 70% to 95%, which may ensure the visibility of the optical effect of the optical layer  21   a.    
     The protective layer  32   a  is in contact with and protects the texture structures  311   a . The difference in refractive index between the protective layer  32   a  and the texture structures  311   a  is greater than or equal to 0.1, preferably greater than or equal to 0.5, which may ensure the optical effect of the texture structures  311   a.    
     Now referring to  FIG. 2 , an optical decorative film  100   b  differs from the optical decorative film  100   a  in that: the texture structures  311   b  of the texture layer  31   b  are grooves in a concave arrangement, and the grooves has a quadrangular cross section. 
     Referring to  FIG. 3 , as compared to the optical decorative film  100   b , an optical decorative film  100   c  is provided with a colorful layer  33   c  between the support layer  1   c  and the texture layer  31   c.    
     Referring to  FIG. 4 , an optical decorative film  100   d  has a decorative layer  3   d  including a binding layer  35   d , a colorful layer  33   d , a texture layer  31   d , and a protective layer  32   d . The binding layer  35   d  bonds the support layer  1   d  to the colorful layer  33   d , the texture layer  31   d  is disposed on the colorful layer  33   d , and the protective layer  32   d  is disposed on the texture layer  31   d . The texture layer  31   d  includes a plurality of texture structures  311   d  set in a gradient arrangement, and the texture structures  311   d  are groove structures. 
     Referring to  FIG. 5 , an optical decorative film  100   e  has a decorative layer  3   e  including a colorful layer  33   e.    
     Referring to  FIG. 6 , an optical decorative film  100   f  has a decorative layer  3   f  including a texture layer  31   f , and the texture layer  31   f  has texture structures  311   f  in a gradient arrangement and is a colored composite layer. 
     Referring to  FIG. 7 , an optical decorative film  100   g  has a decorative layer  3   g  including a gradient colorful layer  33   g . A UV resin is applied on the second side  12   g  and grooves are embossed thereon before curing, and a colorful material is filled in the grooves. In a direction of arrangement, the width of the grooves gradually decreases from both sides inward. After the grooves are filled with the colorful material, the colorful layer  33   g  presents a gradient color. 
     Referring to  FIG. 8 , an optical decorative film  100   h  has a decorative layer  3   h  including a graphic layer  34   h . A UV resin is applied on the second side  12   h  and grooves are embossed thereon before curing, and a material is filled in the grooves to form a graphic. 
     Referring to  FIG. 9 , an optical decorative film  100   i  has a decorative layer  3   i  including a colorful layer  33   i  and a graphic layer  34   i . The colorful layer  33   i  is disposed between a support layer  1   i  and the graphic layer  34   i.    
     Referring to  FIG. 10 , an optical decorative film  100   j  has a decorative layer  3   j  including a binding layer  35   j , a colorful layer  33   j , and a graphic layer  34   j . The graphic layer  34   j  is disposed on the colorful layer  33   j , and the colorful layer  33   j  is bonded to a support layer  1   j  through the binding layer  35   j . The graphic layer  34   j  shows a graphic “LOGO”. 
     Referring to  FIG. 11 , an optical decorative film  100   k  has an optical layer  21   k  on which a protective layer  24   k  is disposed, and a decorative layer  3   k  including a reflective layer  36   k  and a colored layer  37   k . The reflective layer  36   k  is a film layer deposited on the second side  12   k . The colored layer  37   k  is a priming ink layer. 
     Referring to  FIG. 12 , a cover plate for consumer electronics  200  includes a substrate layer  201  and an optical decorative film  100   m  bonded to the substrate layer  201 . The optical decorative film  100   m  has a colored layer  23   m , a reflective layer  22   m , an optical layer  21   m , a support layer  1   m , a binding layer  35   m , a colorful layer  33   m , a texture layer  31   m , a protective layer  32   m , and a second binding layer  38   m  stacked in this order. The second binding layer  38   m  is bonded to the substrate layer  201 . Preferably, the substrate layer  201  is glass. The consumer electronics include cell phones, tablet computers, laptops, cameras and the like. 
     In order to make the foregoing objects, features, and advantages of the present invention more understandable, description of the specific embodiments of the present invention is provided in details above with reference to the accompanying drawings. Many specific details are provided in the above description for the purpose of providing a thorough understanding of the present invention. However, the present invention can be implemented in many ways other than those described above and a person skilled in the art can make similar changes without departing from the spirit of the present invention, and therefore the present invention is not limited to the specific embodiments disclosed above. In addition, the technical features in the examples as described above can be arbitrarily combined. For the sake of conciseness, not all possible combinations of every technical features in the above examples are illustrated, but any combination of these technical features should be regarded as within the scope of the present disclosure as long as there is no contradiction in such a combination. 
     The above examples only demonstrate several embodiments of the present invention which, though described in abundant details, cannot be construed as limitation to the patentable scope of the present invention. It should be noted that, for those of ordinary skills in the art, various changes and modifications can be made without departing from the concept of the present invention and all fall within the protection scope of the present invention. As such, the protection scope of the present invention is defined by the claims appended.