SYSTEM FOR BONDING FILMS AND METHOD FOR PREPARING COMPOSITE FILM USING THE SAME

A system for bonding films includes a first film, a second film having a plurality of elements, a bonding roller, and a deformable roller having a deformable outer layer. The stiffness of the second film is less than that of the first film. By using the system, the deformable outer layer of the deformable roller produces enough deformation during bonding films to fill the area not covered by the plurality of elements on the second film. Therefore, the second film without sufficient stiffness and the first film can be bonded with each other to produce a composite film without wrinkles. A method for preparing a composite film using the system is also disclosed.

CROSS REFERENCES TO RELATED APPLICATIONS

The present application claims priority to Taiwanese Patent Application 112135640 filed in the Taiwanese Patent Office on Sep. 19, 2023, the entire contents of which is being incorporated herein by reference.

BACKGROUND OF THE INVENTION

Field of Invention

The present invention relates to a system for bonding films, in particular to a system including a deformable roller having a deformable outer layer for bonding films and method for preparing a composite film using the same.

Related Art

In recent years, various electronic products have developed towards to lightness, thinness and microminiaturization, which has made the application of the film bonding technologies more extensive. The most common film bonding technology is the roll to roll method, which is a high-efficiency, continuous production method, and is a specialized treatment for the flexible thin films. In this method, the cylindrical base material and the cylindrical thin film material to be bonded are pressed by rollers to achieve continuous bonding. After the bonding is completed, it can be rolled into a cylindrical shape or to be cut as a semi-finished product for subsequent processing.

The main key of the thin film bonding is how to bond the thin film without wrinkles to make the lamination be flat. The WO2011093427A1 mainly uses an insulating film, a metal foil, a divider film, a metal foil and an insulating film to be bonded via thermocompression bonding. Two laminates, each with one metal-plated side, can then be separated from the divider film to achieve the flattened bonding.

However, in case of existing elements on the back of the film to be bonded, the elements will form a three-dimensional obstacle. And there will be a gap space between the three-dimensional obstacles. In addition, the thickness of the film is relatively thin, which cannot provide sufficient stiffness. Therefore, wrinkles will be occurred when bonding to another film and make the forming composite film be unflatness. Many techniques are provided to improve the flatness for the thin films bonding. However, the conditions with three-dimensional obstacles are not considered in these techniques. The production machine needs to be stopped during the process to manually remove the wrinkles, so the production speed is relative low and the labor costs are increased.

Therefore, this invention provides a system for bonding films and method for preparing a composite film using the same to overcome the conventional shortages caused by the three-dimensional obstacles.

SUMMARY OF THE INVENTION

It is an objective of this invention to provide a system for bonding films and method for preparing a composite film using the same to overcome the forgoing shortcomings. The surface of the prepared composite film has no wrinkles, so there is no need to stop the production machine to increase the production speed. Also, since no additional manual processing for removing wrinkles is required, the labor costs can be reduced.

In order to implement the abovementioned, this invention discloses a system for bonding films, which includes a first film, a second film, a bonding roller and a deformable roller. The first film has a first surface and a second surface opposed to the first surface, and the second film has a first surface and a second surface opposed to the first surface. The first surface of the second film is configured to orientate to the first surface of the first film. The second film is with a stiffness less than that of the first film. The second surface of the second film includes a plurality of elements and at least one gap space uncovered by the elements. The bonding roller is configured to contact the second surface of the first film. The deformable roller is configured to contact the second surface of the second film and disposed adjacent the bonding roller. The deformable roller has a deformable outer layer and the deformable roller produces deformation to fill the at least one gap space on the second surface of the second film. The bonding roller is configured to indirectly contact to the deformable roller via the first film and the second film, and the deformable roller is configured to indirectly contact to the bonding roller via the first film and the second film. By using the system, the deformable outer layer of the deformable roller produces enough deformation during bonding films to fill the gap space on the second film, which its stiffness is not sufficient. Therefore, the second film without sufficient stiffness and the first film can be bonded with each other to produce a composite film without wrinkles.

According to the embodiment of this invention, each of the elements is a component related to batteries.

According to the embodiment of this invention, a distance between two adjacent elements is 2-150 millimeters.

According to the embodiment of this invention, the deformable roller includes an inner roller covered by the deformable outer layer.

According to the embodiment of this invention, a hardness of the deformable outer layer of the deformable roller is from 15 Shore A to 50 Shore A.

According to the embodiment of this invention, a thickness of the deformable outer layer of the deformable roller is 1-4 millimeters.

According to the embodiment of this invention, the deformable outer layer of the deformable roller is made of a polymer.

According to the embodiment of this invention, the deformable outer layer of the deformable roller is porous.

According to the embodiment of this invention, the bonding roller has a Shore A hardness greater than that of the deformable roller.

Also, the invention provides a method for preparing a composite film by using the above-mentioned system for bonding films. The method includes the steps of:receiving the first film by the bonding roller and pressing the first surface of the first film toward to the first surface of the second film, and receiving the second film by the deformable roller and pressing the first surface of the second film toward to the first surface of the first film, wherein the deformable outer layer of the deformable roller produces deformation to fill the at least one gap space on the second surface of the second film; andobtaining the composite film that the first film is bonded to the second film.

DETAILED DESCRIPTION OF THE INVENTION

FIG.1is a schematic diagram of the embodiment of the system for bonding films of this invention. The system for bonding films includes a first film50, a second film40including a plurality of elements41, a first feed roller31, a second feed roller32, a bonding roller21and a deformable roller22including a deformable outer layer221.

The first film50is guided by the first feed roller31to the bonding roller50, and the second film40is guided by the second feed roller32to the deformable roller22. The bonding roller21receives the first film50and is configured to indirectly contact to the deformable roller22via the first film50and the second film40for pressing the first film50to the second film40. Also, the deformable roller22receives the second film40and is configured to indirectly contact to the bonding roller21via the first film50and the second film40for pressing the second film40to the first film50. The deformable outer layer221of the deformable roller22produces enough deformation during pressing the second film40to fill the area not covered by the plurality of elements41on the second film40. Therefore, the second film40and the first film50can be bonded with each other to produce a composite film without wrinkles. The description here is only for illustration with drawings, and is not intended to limit the amount and the location of the rollers. In other embodiments, if there are more than three films to be bonded to each other, the number of feeding rollers will increase accordingly.

The first film50has a first surface501and a second surface502opposed to the first surface501. The first surface501is configured to orientate to the second film40, so that the first surface501of the first film50is bonded to the second film40. The thickness of the first film50may range from several microns to thousands of microns. The first film50is PET (polyethylene terephthalate) or other plastic film with sufficient stiffness.

The second film40has a first surface401and a second surface402opposed to the first surface401. The first surface401is configured to orientate to the first film50, so that the first surface401of the second film40is bonded to the first surface501of the first film50. The thickness of the second film50is about 0.001-0.02 millimeters (mm), preferably 0.004-0.006 mm. The second film40is a metal film, such as a copper thin film or an aluminum thin film, etc. There have a plurality of elements41on the second surface402of the second film40and the areas not covered by the plurality of elements41. In the areas not covered by the plurality of elements41, it is defined a gap space411between two adjacent elements41. Therefore, there has at least one gap space411on the second surface402of the second film40. The height of each elements41is 40-200 micrometers. The distance between two adjacent elements41is 2-150 millimeters. The elements41are the components related to batteries, such as a positive active material layer, a negative active material layer, a glue frame and etc. Also, each elements41may be the same or different components related to batteries. In one embodiment, the elements41may be the one of the positive active material layer, the negative active material layer or the glue frame. In another embodiment, the elements41may be the positive active material layer, the negative active material layer or the glue frame respectively.

In an embodiment, an adhesive substance is applied to the first surface501of the first film50for bonding to the first surface401of the second film40. The adhesive substance may be an adhesive glue or an adhesive gel.

In this invention, the second film40is with a stiffness less than that of the first film50. The stiffness is the ability for resisting bending of a thin film. Therefore, in this invention, the second film40is easier to generate wrinkles than the first film50, due to the stiffness of the second film40is less than that of the first film50.

The bonding roller21receives the first film50guided by the first feed roller31and continually contacts to the second surface502of the first film50. The bonding roller21may be all kinds of hollow or solid roller, such as a steel roller, a rubber coated roller. The bonding roller21has a Shore A hardness greater than that of the deformable roller22.

The deformable roller22is disposed adjacent the bonding roller21. The deformable roller22receives the second film40guided by the second feed roller32. The deformable roller22has a deformable outer layer221and an inner roller222covered by the deformable outer layer221, as shown inFIG.2. A thickness of the deformable outer layer221is 1-4 millimeters, which is made of soft polymer or is porous. For example, the polymer is, but not limited to, rubber. The diameter of the inner roller222is 50-250 millimeters3. The inner roller222may be a steel or an aluminum roller which is solid or hollow. A hardness of the deformable outer layer221is from 15 Shore A to 50 Shore A.

As shown inFIG.3, there have a plurality of elements41on the second surface402of the second film40. Since the elements41have a certain thickness and weight, they have a certain mechanical strength. Therefore, the stiffness of the areas, which are covered by the elements41on the second film40can be enhanced. For the areas, which are not covered by the elements41on the second film40, it is easier to generate wrinkles, due to not supported by the elements41, especially in the gap space411between two adjacent elements41on the second surface402. Therefore, in this invention, the deformable outer layer221of the deformable roller22produces enough deformation during bonding films to fill and press the areas not covered by the plurality of elements41on the second surface402of the second film40. In particularly, the deformable outer layer221produces enough deformation by against the elements41on both sides to fill the gap space411to enhance the mechanical strength on this area during bonding. Therefore, when the deformable roller22pressing the second film40and the bonding roller21pressing the first film50, the first film50and the second film40can be bonded flatly with each other to produce a composite film without wrinkles.

FIG.4Ais a schematic diagram showing the deformable roller22and the bonding roller21pressing the first film50and the second film40respectively. The bonding roller21presses the first surface501of the first film50toward to the first surface401of the second film40. Also, the deformable roller22presses the first surface401of the second film40toward to the first surface501of the first film50to make the first film50and the second film40be bonded with each other. In the figure, the elements41on the second surface402of the second film40is arranged in a matrix. It can also be in an irregular arrangement.

FIG.4Bis a cross-sectional view taken along a central line of a rolling axis of the deformable roller22and a central line of a rolling axis of the bonding roller21. InFIG.4B, the bonding roller21presses the first surface501of the first film50toward to the first surface401of the second film40, and the deformable roller22presses the first surface401of the second film40toward to the first surface501of the first film50. In details, the deformable outer layer221of the deformable roller22produces enough deformation to fill and press the areas not covered by the plurality of elements41on the second surface402of the second film40. In particularly, the deformable outer layer221produces enough deformation to fill the gap space411between the adjacent elements41. Therefore, the first film50and the second film40can be bonded to produce a composite film without wrinkles. The deformable outer layer221may has a plurality of holes2211inside, seeFIG.5A, or have a plurality of pores2212on the outer surface, seeFIG.5B. These types of the deformable outer layer221can produce enough deformation to fill the gap space411between the adjacent elements41during bonding.

FIG.6is a flow diagram of the method for preparing a composite film by using the system for bonding films of this invention. The method for preparing the composite film includes the steps of:in the step S601, providing a first film50;in the step S602, providing a second film40;in the step S603, guiding the first film50to the bonding roller21by the first feed roller31and guiding the second film40to the deformable roller22by the second feed roller32;in the step S604, receiving the first film50by the bonding roller21and pressing the first surface501of the first film50toward to the first surface401of the second film40, and receiving the second film40by the deformable roller22and pressing the first surface401of the second film40toward to the first surface501of the first film50, wherein the deformable outer layer221of the deformable roller22produces deformation to fill the at least one gap space411on the second surface402of the second film40; andin the step S605, obtaining the composite film that the first film50is bonded to the second film40.

Accordingly, the present invention provides a system for bonding films and method for preparing a composite film using the same to solve the problems of generating wrinkles when the film without sufficient stiffness bond to another film, especially suitable for the film without sufficient stiffness having a plurality of elements thereon. The system of this invention includes the deformable roller, which produces enough deformation during bonding to fill the gap space between the elements of the film without sufficient stiffness. Therefore, the film without sufficient stiffness and another film can be bonded with each other flatly to produce a composite film without wrinkles.