HK40001504B - Systems and methods for a multi-material extruded zipper - Google Patents

Description

Systems and methods for multi-material extruded zippers

This application is a divisional application of a Chinese patent application filed on January 25, 2013, with national application number 201480005985.5 and entitled “System and method for multi-material extrusion molding of zippers”.

Background Art

Most, but not all, polymer zipper systems are made from olefin-based polymers, such as polypropylene or polyethylene. Polymer zipper profiles are manufactured using an extrusion process. Olefin-based systems have advantages over many polymer zipper systems due to the inherent low cost of polymer resins and their low coefficient of friction. A low coefficient of friction is important so that the zipper's ball and socket can be pushed together with minimal force. However, olefin-based zipper systems have their limitations. Most olefin-based zipper systems made from polypropylene and polyethylene are not durable when used in external environments where temperature extremes can affect material properties. Polypropylene and polyethylene zipper profiles lack tensile and tear strength, as well as good elongation properties. They also have excessive compression set when subjected to stress loads at higher temperatures. Therefore, they are not used in extreme applications such as "waterproof bags" and "swimsuits," which are commonly used in hot environments. Instead, they are used in sandwich bags and other low-performance applications.

Summary of the Invention

In one embodiment, the zipper includes a ball head portion. The zipper portion also includes a slot portion. The ball head portion includes a front edge, the front edge being composed of a first material having a low coefficient of friction. The ball head portion includes a rear edge and a neck portion, the rear edge and the neck portion being composed of a second material. The slot portion includes a slot opening, the slot opening being composed of the first material. The slot portion includes a slot interior, the slot interior being composed of the second material. Optionally, the first material and the second material are co-extruded. In an alternative embodiment, the zipper also includes a first zipper sliding support portion and a second zipper sliding support portion, the first zipper sliding support portion and the second zipper sliding support portion being interconnected with the ball head portion and the slot portion, respectively, the first body of the first zipper sliding support portion and the second body of the second zipper sliding support portion being respectively composed of the second material, wherein the first sliding section of the first zipper sliding support portion is composed of the first material, and the second sliding section of the second zipper sliding support portion is composed of the first material. Optionally, the zipper includes a first flange portion and a second flange portion, the first flange portion and the second flange portion being interconnected with the first zipper sliding support portion and the second zipper sliding support portion, respectively, and the first flange portion and the second flange portion being composed of a third material. In another alternative, the second material has a harderness greater than that of the first material and the third material. Optionally, the first material has a harderness greater than that of the third material. In another alternative, the first, second, and third materials are thermoplastic polyurethanes. Optionally, the first material has a hardness of 74 Shore D. Alternatively, the second material has a hardness of 95 Shore A. Optionally, the third material has a hardness of 75 Shore A. Alternatively, the first, second, and third materials are extruded together as part of a triple extrusion process; and because the first, second, and third materials are composed of the same thermoplastic, the first, second, and third materials bond together during the extrusion process. Optionally, the zipper further comprises a slider oriented on the first zipper slide support portion and the second zipper slide support portion, the slider being operable to close the zipper.

In one embodiment, a method of forming a zipper includes extruding a first material as part of a triple extrusion process, the first material forming the front edge of a ball head of the zipper and the first material forming the opening of a slot. The method also includes extruding a second material as part of the triple extrusion process, the second material forming the rear edge and neck of the ball head and the second material forming the interior of the slot. Optionally, the first material also forms the first sliding section of a first zipper slide support and the second sliding section of a second zipper slide support, while the second material also forms the first body of the first zipper slide support and the second body of the second zipper slide support, respectively, interconnecting the ball head and the slot. Alternatively, the method includes extruding a third material, the third material forming the first and second flange portions, interconnecting the first and second zipper slide support, respectively. Optionally, the second material has a higher hardness than the first and third materials. Alternatively, the first material has a higher hardness than the third material. Optionally, the first, second, and third materials are thermoplastic polyurethane. Alternatively, the first material has a hardness of 74 Shore D. Alternatively, the second material has a hardness of 95 Shore A. Alternatively, the third material has a hardness of 75 Shore A. Optionally, the first material, the second material, and the third material are extruded together as part of a triple extrusion process; and because the first material, the second material, and the third material are composed of the same thermoplastic, the first material, the second material, and the third material are bonded together during the extrusion process. Optionally, the method further includes providing a slider oriented on the first zipper slide support portion and the second zipper slide support portion, the slider being operable to close the zipper.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 shows an embodiment of a multi-material extruded zipper (MMEZ);

FIG2 a shows another view of the MMEZ of FIG1 ;

FIG2 b shows the MMEZ of FIG1 including a slide;

FIG3 shows a perspective view of the MMEZ of FIG1 including a slide;

Figure 4a shows the MMEZ of Figure 1;

FIG4 b shows the MMEZ of FIG1 welded to a bag;

FIG5 shows a version of the MMEZ of FIG1 with a harder flange material; and

6a and 6b illustrate exemplary skids to be used with the MMEZ of FIG. 1 .

DETAILED DESCRIPTION

Embodiments of a multi-material extruded zipper (MMEZ) and methods of using and manufacturing the same are described herein. Essentially, it is advantageous for the various components of the MMEZ to be constructed from multiple thermoplastic pieces extruded together, wherein the multiple thermoplastic pieces have different characteristics, such as different tensile strengths, different elongation properties, and different hardnesses.

SubZipper is made of thermoplastic polyurethane (TPU). Unlike olefin-based plastics, TPU is a cross-linked polymer elastomer that exhibits rubber-like properties at both low and high hardness levels. TPU polymers exhibit extremely high tensile and tear strengths, as well as high elongation at both high and low temperature extremes. TPU also has excellent resistance to compression set. TPU polymers are designed for use in extreme outdoor conditions.

Unlike polypropylene and polyethylene, TPU does not have a low coefficient of friction (LCOF). Therefore, polymer zipper systems made from TPU require frequent application of a "rub-on" lubricant to allow the zipper's ball and socket to easily seat together (as shown in Figures 1a and 1b). Unfortunately, this "rub-on" lubricant gradually depletes over a short period of time. The present invention addresses this shortcoming.

Basically, the MMEZ is extruded so that the areas requiring a low friction surface are extruded from the LCOF material, and the areas requiring flexibility and high strength are constructed from the TPU material.

FIG1 illustrates an embodiment of an MMEZ 100. MMEZ 100 includes a slot 110 for receiving a ball 105. Ball 105 includes a front edge 115 that has been extruded with an LCOF coating as part of a triple extrusion process. As described below, a rear edge 116 and a neck 117 of ball 105 are constructed from a softer TPU material. Slot 110 includes a top slot opening 120 and a bottom slot opening 125, where an LCOF coating has been extruded. The interior of slot 110 is formed from a similar material as rear edge 116 and neck 117, typically a TPU material that is softer than the LCOF coating. The remainder of the body of zipper 100 is formed from sliding supports 150 and 155, which are formed from the softer TPU material that forms neck 117 of ball 105. Similarly, portions of sliding supports 150 and 155 are coated with LCOF during the extrusion process. The sliding supports 150, 155 include first and second sliding segments 130, 135, each comprised of an LCOF coating formed during the extrusion process. The zipper 100 also includes flanges 140, 145 on either side of the sliding supports 150, 155. These flanges 140, 145 are also comprised of a TPU material. This material is generally softer than the LCOF coating. It may also be softer than the TPU material used to construct the sliding supports 150, 155.

It should be noted that, typically, the un-LCOF-coated areas of the ball and socket and the sliding bearing are formed together as a single component. Generally, zipper 100 can be considered to comprise: a ball and socket portion formed from a first material, including the sliding bearing; an LCOF coating made from a second material located on the low-friction area of zipper 100; and flanges composed of a third material located on either side of zipper 100. All three materials are extruded together using a triple-extrusion manufacturing process. Because each of these materials is TPU-based, they bond together during the extrusion process. Each of these materials exhibits different properties based on its chemical composition. The first material forming the ball and socket (and the sliding bearing) is made of 95 Shore A TPU. The second material, the LCOF coating, is made of a harder 74 Shore D TPU with an LCOF additive. The RF welding flanges 140, 145 are made of a softer 75 Shore A TPU. Three different materials, used to achieve the three independent properties desired in the final product assembly, allow the zipper to function correctly. Alternatively, only two materials could be used: a first, harder material with an LCOF additive, and softer materials for the ball, socket, and flange. Alternatively, more than three materials could be used, and while still using the other three materials described above, a portion of the sliding bearing could be made harder than the neck and rear edge of the ball. Numerous alternatives will be apparent to those skilled in the art in light of this disclosure.

The LCOF TPU used in areas 220, 225, 230, and 235 of Figure 2a eliminates the need for liquid lubricants, which must be frequently applied for proper function of the TPU zipper. Therefore, the use of LCOF TPU solves two issues regarding the functionality of the ball and socket. First, the LCOF coating can be applied at critical points on the extruded profile. As shown, the LCOF coating can be applied to the front edge 115 of the ball 105 and the socket openings 120 and 125 of the socket. This allows the ball and socket to seat together with minimal "insertion" force. However, the interior 250 and rear edge 116 of the socket 110 are uncoated to achieve a high extraction force. This makes it more difficult to pull the ball and socket apart. As mentioned above, TPU has a very high coefficient of friction. When the ball and socket are seated together, they rely on specific areas of the extruded profile that are not coated with LCOF TPU to maintain the zipper ball and socket in place. Thus, coating the ball and socket profiles at critical locations achieves easy insertion and difficult extraction. It should also be noted that the LCOF coating does not fade away and does not need to be reapplied. This is considered a significant advantage over existing systems that require re-lubrication of specific surfaces. When the liquid LCOF coating is not applied during the extrusion process, it is difficult to place the coating in critical locations. The liquid LCOF coating applied after extrusion tends to cover every surface of the profile as it "flows" into place. Therefore, the extraction force with the liquid LCOF coating is much smaller. Figure 2b shows the addition of a slider 295 for closing the zipper assembly.

Second, as shown in Figure 3, the sub-zipper system relies on a "slider" mechanism 310 to connect the left side 320 and right side 330 of the zipper assembly. As the slider moves along the extruded contour during assembly, there is an obstruction between the slider and the zipper contour. Without the LCOF coating, the slider would not move. Therefore, an LCOF coating is applied to the sliding sections 130 and 135 in Figure 1 during extrusion. Applying the LCOF coating to these areas allows the slider to function with minimal force.

Certain areas are intentionally left without an LCOF coating, as indicated. Sealing areas 260, 270, 280, and 290 need to be more flexible to form a proper seal. This is why two different materials are used for the main body of zipper 100, including ball 105 and socket 110. To properly seal the zipper and allow for flexibility in end use, the hardness cannot be higher than 95 to 100 Shore A. Above 100 Shore A, it would be difficult to properly connect the zipper components. Therefore, this solution enables the placement of a harder LCOF material coating in strategic locations, if needed, without affecting the function of the zipper components.

FIG4 a shows flanges 130 , 135 , which may be referred to as “RF welded flanges.” The MMEZ 100 is designed for use in waterproof bag assemblies, high boots for wading, jacket pockets, and other waterproof and water-resistant applications. In order for the MMEZ 100 to be assembled into a final product, it must be sealed during assembly. Radio frequency (RF) welding is used to melt the TPU zipper into the final product. As an illustration, olefin-based polymers do not respond to RF welding. Therefore, a TPU-based zipper is required for this application. However, it has been determined that TPU with a hardness greater than 75 Shore A may be too hard for use in the flanges 130 , 135 for this application. The MMEZ 100 may work with a harder hardness; however, this operation would be difficult and undesirable. When assembled to a thin jacket fabric, the flange forms a noticeable indentation 410 (as shown in FIG4 b ) in the jacket 420 , which is undesirable to the manufacturer or user. In this area, by extruding a softer durometer TPU—for example, 75 Shore A—this allows the RF weld flange to be "draped" by the fabric, rather than showing clearly through it. For a secondary purpose, a lower durometer TPU is also used in the RF weld flange. As shown in Figure 5, the MMEZ 100 slider 310 opens the ball and socket by separating them in directions 510, 520. The resistance of the slider 310 decreases as the durometer of the RF weld flanges 130, 135 decreases. The lower the durometer, the easier it is to deflect/deform the flanges 130, 135, thereby providing less resistance to the slider. This also has another effect on the assembly. When the ball and socket profiles can open at a greater angle, the slider can be shorter from front to back. Consequently, the slider requires less "leading in" to open the rear separator of the zipper.

Figures 6a and 6b show an exemplary slider for use with an MMEZ. The slider includes an upper slider body 610, a track retainer 620, and a pull receiver 630. The track retainer 620 fits into the area 22 shown in Figure 2a. The slider shown is merely an exemplary slider, and those skilled in the art will be able to identify various options based on this disclosure.

The above detailed description is of a few embodiments for implementing systems and methods for forming a multi-material extruded zipper (MMEZ) and MMEZ systems and is not intended to limit the scope. The appended claims set forth several embodiments for forming an MMEZ and systems and methods and MMEZ systems that are disclosed in greater detail.

Claims (21)

1. A zipper, comprising: The head of the ball; and The slot portion is for receiving the ball head, wherein the ball head includes a front edge formed by an extruded coating of a first material having a low coefficient of friction, the ball head includes a pair of rear edges and a neck formed by a second material, the slot portion includes a top slot opening and a bottom slot opening formed by an extruded coating of the first material, and the slot portion includes a slot interior formed by the second material; A first zipper sliding support and a second zipper sliding support are respectively connected to the ball head and the slot portion. The first body of the first zipper sliding support and the second body of the second zipper sliding support are respectively made of the second material. The first sliding section of the first zipper sliding support is made of an extruded coating of the first material, and the second sliding section of the second zipper sliding support is also made of an extruded coating of the first material. 2. The zipper according to claim 1, wherein the first material and the second material are co-extruded. 3. The zipper according to claim 1, further comprising: A first flange portion and a second flange portion are respectively connected to the first zipper sliding support portion and the second zipper sliding support portion, and the first flange portion and the second flange portion are made of a third material. 4. The zipper according to claim 3, wherein the hardness of the second material is higher than the hardness of the first material and the hardness of the third material. 5. The zipper according to claim 4, wherein the hardness of the first material is higher than the hardness of the third material. 6. The zipper according to claim 5, wherein the first material, the second material, and the third material are thermoplastic polyurethane. 7. The zipper according to claim 6, wherein the first material has a hardness of 74 Shore D. 8. The zipper according to claim 6, wherein the second material has a hardness of 95 Shore A. 9. The zipper according to claim 6, wherein the third material has a hardness of 75 Shore A. 10. The zipper of claim 6, wherein, as part of a triple extrusion process, the first material, the second material, and the third material are extruded together; and since the first material, the second material, and the third material are made of homogeneous thermoplastics, the first material, the second material, and the third material are bonded together during the extrusion process. 11. The zipper according to claim 3, further comprising: A slider is oriented on the first zipper sliding support and the second zipper sliding support, and the slider is operable to close the zipper. 12. A method of forming a zipper, the method comprising: As part of a triple extrusion process, a coating of a first material is extruded, the coating of which forms the leading edge of the ball head of the zipper, and the coating of the first material forms the top slot opening and the bottom slot opening of the slot portion; and As part of the triple extrusion process, a second material is extruded, which forms a pair of rear edges and a neck of the ball head, and forms the slot interior of the slot portion. The coating of the first material also forms a first sliding section of the first zipper sliding support and a second sliding section of the second zipper sliding support, and the second material also forms a first body of the first zipper sliding support and a second body of the second zipper sliding support, respectively. The first zipper sliding support and the second zipper sliding support are interconnected with the ball head and the slot portion. 13. The method of claim 12, further comprising: A third material is extruded to form a first flange portion and a second flange portion, the first flange portion and the second flange portion being respectively connected to the first zipper sliding support portion and the second zipper sliding support portion. 14. The method according to claim 13, wherein the hardness of the second material is higher than that of the first material and the third material. 15. The method according to claim 13, wherein the hardness of the first material is higher than the hardness of the third material. 16. The method of claim 13, wherein the first material, the second material, and the third material are thermoplastic polyurethane. 17. The method of claim 13, wherein the first material has a hardness of 74 Shore D. 18. The method of claim 13, wherein the second material has a hardness of 95 Shore A. 19. The method of claim 13, wherein the third material has a hardness of 75 Shore A. 20. The method of claim 13, wherein, as part of a triple extrusion process, the first material, the second material, and the third material are extruded together; and since the first material, the second material, and the third material are made of homogeneous thermoplastics, the first material, the second material, and the third material are bonded together during the extrusion process. 21. The method of claim 13, further comprising: A slider is provided, the slider being oriented on the first zipper sliding support and the second zipper sliding support, the slider being operable to close the zipper.