Patent Publication Number: US-2023150229-A1

Title: Composite Film and Production Method Thereof

Description:
FIELD OF INVENTION 
     A composite film, especially to a composite film with stacked heterogeneous materials and strength enhancement. 
     BACKGROUND OF THE INVENTION 
     Common composite films are manufactured by steps of impregnating fiber cloths with a resin and then curing the resin, wherein the pre-preg fiber cloths can be stacked or cut into shapes needed. After the pre-preg fiber cloths stacked as needed, subsequent processing and forming can be done according to the thermosetting or thermoplastic characteristics of the resins. 
     Nevertheless, common composite films have greater stress resistant abilities along the axial direction of the fibers and very poor stress resistant abilities along the radial direction of the fibers. Therefore, when pre-preg fiber cloths stacked as needed, the composite films can have greater stress resistant abilities along the two-dimensional directions (e.g., the directions of the X axis and Y axis) and very poor stress resistant abilities along the stacking direction (e.g., the direction of the Z axis). 
     For example, common composite films can have greater tensile strength along the two-dimensional directions, and when external forces (e.g., impact or bend) are applied along the stacking direction on the composite films, the composite films are peeled off from the laminated structure of the pre-preg fiber cloths. Furthermore, when the laminated structure is peeled off, the stress resistant abilities of each direction decrease significantly, and the fibers of the peeled part of the laminated structure of the composite films might break and cause the breakage of the composite films. 
     In addition, common composite films comprise many fibers that can provide transmission routes to disperse stresses through the axial directions of the fibers, so composite films can have greater stress resistant abilities along the axial direction of the fibers. Nonetheless, when a portion of the fibers in the composite films break, since the broken fibers cannot disperse stresses, the unbroken fibers have to bear all the stresses. Therefore, the unbroken fibers are overloaded and gradually broken down to cause a part of the composite films to break down entirely. 
     Therefore, a novel composite film and the manufacturing methods of the novel composite film is required to solve the peeling-off of the laminated layers and the transferring effect of broken fibers of conventional composite film. 
     SUMMARY OF THE INVENTION 
     In order to solve the aforementioned problems of conventional composite films, the present invention provides a composite film comprising sequentially stacked: a first fiber layer, a metal layer with several holes, and a second fiber layer, wherein: a stitching structure is arranged along a horizontal direction of the first fiber layer and the second fiber layer within areas of the holes of the metal layer, the stitching structure in each of the holes is connected, but the stitching structures in different holes are not mutually connected, and the first fiber layer and the second fiber layer are tightly fastened together and fall into the holes. 
     Wherein, the first fiber layer or the second fiber layer comprises a single layer of fiber cloth or multiple layers of fiber cloths, wherein said fiber cloth is unidirectional fabric, woven fabric, or pre-preg fabric impregnated with a resin, wherein said fiber cloth comprises carbon fibers, glass fibers, Kevlar fibers, ceramic fibers, or combinations thereof. 
     Wherein, the resin comprises epoxy resins, thermoplastic polyurethane, polycarbonate, polyetheretherketone, polypropylene, or combinations thereof. 
     Wherein, when the first fiber layer or the second fiber layer comprises multiple layers of fiber cloths, the fiber cloths are stacked together with different fiber orientation. 
     Wherein, the stitching structure comprises Kevlar thread or metal thread. 
     Further, this invention also provides a production method of the aforementioned composite film, comprising steps of: stacking a first fiber layer, a metal layer with several holes, and a second fiber layer in sequence; sewing stitching structures along the horizontal direction of the first fiber layer and the second fiber layer within the areas of the holes of the metal layer to make the first fiber layer, the metal layer, and the second fiber layer fastened together, wherein each of the stitching structures sewed in each of the holes is connected, but the stitching structure is not connected with other stitching structures in other holes; and curing the first fiber layer, the metal layer, and the second fiber layer that are stacked and fastened to make the first fiber layer and the second fiber layer align with the positions of the holes of the metal layer, and the first fiber layer and the second fiber layer are tightly fastened together and fall into the holes. 
     Wherein, further processing and shaping the composite film to form a finished product. 
     Wherein, rolling process is applied to remove bubbles between the first fiber layer, the metal layer, and the second fiber layer during the step of curing. 
     As above description, the present invention has beneficial effects and advantages as following:
     1. The stitching structures of this invention extend through the first fiber layer and the second fiber layer to fortify the stress resistant abilities along the radial direction of the composite film, and thus the peeling off of the stacked structure from the radial direction is avoided. At the same time, with the independent stitching structure formed independently in each of the holes of the metal layer, the stitching structures would not interact with each other. Accordingly, even one of the stitching structures is broken, other stitching structures would not be affected, effectively increasing the durability of the product of this invention.   3. The stitching structures do not need to penetrate the metal layer, so the stitching structures are essentially sewed through the first fiber layer and the second fiber layer. Hence, the strength of the heterogeneous plate can be increased by increasing the thickness of the metal layer of this invention, the total thickness of the plate and the application ranges of this invention are simultaneously increased.   

    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The steps and the technical means adopted by the present invention to achieve the above and other objects can be best understood by referring to the following detailed description of the embodiments and the accompanying drawings. These embodiments are not restrictive, and in these embodiments, same numberings indicate same structures, wherein: 
         FIG.  1    is an exploded view of an embodiment of a composite film in accordance with the present invention. 
         FIG.  2    is a schematic diagram of an embodiment of a composite film in accordance with the present invention. 
         FIG.  3    is a block diagram of a production method for a composite film in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference will now be made in detail to the present preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts. It is not intended to limit the method by the exemplary embodiments described herein. In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to attain a thorough understanding of the disclosed embodiments. It will be apparent, however, that one or more embodiments may be practiced without these specific details. As used in the description herein and throughout the claims that follow, the meaning of “a”, “an”, and “the” may include reference to the plural unless the context clearly dictates otherwise. Also, as used in the description herein and throughout the claims that follow, the terms “comprise or comprising”, “include or including”, “have or having”, “contain or containing” and the like are to be understood to be open-ended, i.e., to mean including but not limited to. 
     Preferred Embodiments of Composite Films 
     With reference to  FIG.  1    and  FIG.  2   , a first preferred embodiment of a composite film  10  in accordance with the present invention includes: a first fiber layer  11 , a metal layer  12  with multiple holes  121 , and a second fiber layer  13 , wherein: a stitching structure  14  is arranged along the horizontal direction of the first fiber layer  11  and the second fiber layer  13  within the hole  121  area of the metal layer  12 ; and the stitching structures  14  in each hole  121  are connected, but the stitching structures  14  in different holes  121  are not mutually connected, and the first fiber layer  11  and the second fiber layer  13  are tightly fastened together and fall into the holes  121 . 
     Wherein, the first fiber layer  11  and the second fiber layer  13  in this embodiment are primarily unidirectional fabric or woven fabric comprising carbon fibers, glass fibers, Kevlar fibers, ceramic fibers, or a combination thereof. Preferably, the unidirectional fabric or the woven fabric is pre-preg fiber cloth comprises aforementioned fibers impregnated with a resin, wherein the resin comprises epoxy resins, thermoplastic polyurethane, polycarbonate, polyetheretherketone, polypropylene, or a combination thereof. The first fiber layer  11  or the second fiber layer  13  can be made up of a single layer of fiber cloth or multiple layers of fiber cloths, and when the first fiber layer  11  or the second fiber layer  13  is made up of multiple layers of fiber cloths, each of the fiber cloths can be stacked with different fiber orientation angle to each other fiber cloths as needed, and the fiber orientation angle between two of the fiber cloths includes but not limit to 0 degree, 45 degree, 90 degree. In practice, the stacking angle of the first fiber layer  11  or the second fiber layer  13  can be adjust to any arbitrary angle as needed, or the first fiber layer  11  or the second fiber layer  13  can be weaved in advanced at specific interweaving angle of the fibers as needed. The stitching structure  14  can include but not limit to Kevlar thread or metal thread. 
     The metal layer  12  is preferably a metal plate with several holes  121 , and the shapes of the holes  121  are not restricted. In the embodiment, the holes  121  shown are rectangular with dimensions of 1 cm*1 cm, and each of the stitching structures  14  is arranged in one of the holes  121 , and the stitching structure  14  is not connected with other stitching structures  14  in other holes  121 . 
     Preferred Embodiment of the Production Method 
     With reference to  FIG.  3   , the preferred embodiment of the production method of the aforementioned composite film  10  in accordance with the present invention comprises steps of:
     Step S 1 : stacking the first fiber layer  11 , the metal layer  12  with several holes  121 , and the second fiber layer  13  in sequence;   Step S 2 : sewing stitching structures  14  along the horizontal direction of the first fiber layer  11  and the second fiber layer  13  in the areas of the holes  121  of the metal layer  12  to make the first fiber layer  11 , the metal layer  12 , and the second fiber layer  13  fastened together, wherein each of the stitching structures  14  sewed in each of the holes  121  is connected with other in the hole  121 , but the stitching structure  14  is not connected with other stitching structures  14  in other holes  121 ; and   Step S 3 : curing the first fiber layer  11 , the metal layer  12 , and the second fiber layer  13  that are stacked and fastened to form the composite film  10  in accordance with the present invention, wherein at the hole  121  area of the metal layer  12 , the first fiber layer  11  and the second fiber layer  13  are tightly fastened together and fall into the holes  121 .   Step S 4  (optional, not shown in the figure): further processing and shaping the composite film  10  to form a finished product.   

     In the preferred embodiments of this present invention, the sewing process to form the stitching structure  14  to the stacked first fiber layer  11  and the second fiber layer  13  is before the curing of the first fiber layer  11  and the second fiber layer  13 ; that is, when the first fiber layer  11  and the second fiber layer  13  are still soft, the stitching structure  14  could be sewed through the first fiber layer  11  and the second fiber layer  13 . 
     In other preferred embodiments of this present invention, when the first fiber layer  11  or the second fiber layer  13  contains multiple layers with a resin, curing can be done on each of the layers separately and adhere them together later, or the layers can be cured together. When the first fiber layer  11  and the second fiber layer  13  are cured separately and adhere together later, a resin adhesive layer (not shown in figures) can be applied between the multiple layers of the first fiber layer  11  or the second fiber layer  13  to adhere multiple layers of the fiber cloths 
     Further, in the preferred embodiments of this present invention, to avoid the adhesive resin contains bubbles and causes the adhesion between the multiple layers of the first fiber layer  11  or the second fiber layer  13  to be insecure or peeled off after the composite film  10  is cured and formed, the bubbles of the resin can be removed with rolling process during manufacturing to improve the adhesiveness between layers. In another embodiment of the present invention, bubbles can also be removed by vacuumizing the resin. 
     In the structural design of the embodiments of this present invention, by the stitching structures  14  penetrating through the first fiber layer  11  and the second fiber layer  13 , the stress resistant abilities along the radial direction of the composite film  10  is fortified, and thus avoid the peeling off of the stacked structure from the radial direction. At the same time, with the independent stitching structure  14  formed independently in each of the holes  121  of the metal layer  12 , the stitching structures  14  would not interact with each other, so that even one of the stitching structure  14  is broken, other stitching structures  14  would not be affected, effectively increasing the durability of the product of this invention. 
     Furthermore, although the stitching structures  14  penetrate through the metal layer  12 , the stitching structures  14  are essentially sewed through the first fiber layer  11  and the second fiber layer  13 . Hence, the strength of the heterogeneous plate can be increased by increasing the thickness of the metal layer  12  of this invention. 
     It should be noted that in order to simplify the expression of the technology disclosed in the present invention for better understanding of one or more embodiments of the invention, in the foregoing description of the embodiments of the invention, sometimes multiple features are combined into one embodiment, drawings or descriptions thereof. However, this way of disclosure does not mean that the claimed object of the present invention requires more features than those mentioned in the examples. In fact, claimed features may be less than all features of a single foregoing disclosed embodiment without reducing the effects of the invention 
     In some embodiments, numbers describing components and attribute quantities are used. It should be understood that such numbers used in the description of embodiments use words “around”, “approximately” or “about” in some examples. Unless otherwise stated, “around”, “approximately” or “about” indicates that the stated figure allows for a variation of ±20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximations that may vary depending upon the desired characteristics of individual embodiments. In some embodiments, numerical parameters should take into account the specified significant digits and adopt the general digit reservation method. Although the numerical ranges and parameters used to demonstrate the breadth of scope in some embodiments of the invention are approximations, in specific embodiments such numerical values are as precisely as practicable. 
     The above specification, examples, and data provide a complete description of the present disclosure and use of exemplary embodiments. Although various embodiments of the present disclosure have been described above with a certain degree of particularity, or with reference to one or more individual embodiments, those with ordinary skill in the art could make numerous alterations or modifications to the disclosed embodiments without departing from the spirit or scope of this disclosure. 
     Description of Symbols 
     
         
           10  composite film 
           11  first fiber layer 
           12  metal layer 
           121  hole 
           13  second fiber layer 
           14  stitching structure 
         S 1 -S 3  steps