High connection strength magic tape and its preparation process

Abstract

This invention discloses a high-strength hook and loop fastener and its manufacturing process, belonging to the field of hook and loop fastener technology. It includes a hook side and a loop side. The hook side uses a composite thermoplastic polyester elastomer composed of a blend of polybutylene terephthalate and polyethylene terephthalate as the hook tooth material. By optimizing the injection molding process parameters, it achieves high toughness while forming a strong anchoring structure with the base fabric, which is a blend of polyester fibers and low-melting-point polyester staple fibers. The loop side involves plasma-assisted chitosan microsphere treatment of the loop fibers composed of polyamide, constructing a micro-nano composite texture on its surface, significantly improving its surface friction coefficient and cohesion. This invention, without significantly increasing costs, achieves a significant improvement in the peel strength and shear strength of the hook and loop fastener through the synergistic effect of the hook and loop sides, while also greatly improving its fatigue resistance and extending its service life.

Description

Technical Field

[0001] This invention belongs to the field of hook and loop fastener technology, specifically relating to a high-strength hook and loop fastener and its manufacturing process. Background Technology

[0002] Velcro, also known as hook and loop fasteners, consists of two parts: a hook side and a loop side. The connection is created by the interlocking of the hook teeth on the hook side and the fiber loops on the loop side. Due to its ease of use and ability to be repeatedly opened and closed, it is widely used in clothing, footwear, bags, medical, military and sporting goods.

[0003] However, traditional Velcro has revealed some inherent technical flaws during long-term use, severely limiting its application in high-end or high-load scenarios. These flaws are mainly manifested in the following aspects: Limited connection strength: The hooks of traditional Velcro are usually injection molded from rigid nylon or polyester materials. Although the initial hooking force is acceptable, the toughness is insufficient. Under large lateral shear forces or vertical peeling forces, the hooks are prone to breakage or being pulled off from the base fabric, leading to connection failure. The napped side is made of nylon or polyester fibers, with a smooth fiber surface and a low coefficient of friction, resulting in limited cohesion with the hooks and further limiting the overall connection strength.

[0004] Poor fatigue resistance, prone to detachment and pilling: During repeated opening and closing, the hook teeth repeatedly snag and separate from the napped fibers. If the hook tooth material lacks sufficient toughness, fatigue cracks easily form at the root after thousands of cycles, eventually leading to breakage. Simultaneously, the sharp hook teeth continuously cut and rub against the smooth napped fibers, causing them to break, pill, or even fall off, resulting in "bald patches" on the napped surface. This not only reduces the connection strength but also affects the product's appearance and lifespan.

[0005] Poor environmental adaptability: The performance of traditional hook and loop fasteners deteriorates sharply in humid, oily, or extreme temperature environments. For example, moisture weakens the rigidity of nylon materials and causes them to swell, altering the shape and mechanical properties of the hooks; oil adheres to the fiber surface, acting as a lubricant and significantly reducing the friction between the hook and loop surfaces.

[0006] Existing technologies have made some attempts to address the above problems. For example, some patents improve hooking force by increasing the density of the hook teeth or changing their shape (such as mushroom head shape), but this often leads to increased material usage and higher production costs. Furthermore, after repeated use, stress concentration becomes more severe, which accelerates the damage to the hook teeth. Other technical solutions propose chemical grafting of the fibers or coating with a high coefficient of friction coating, but these methods are usually complex and costly, and the coating may have durability issues, easily peeling off and failing after repeated washing or friction.

[0007] In summary, existing hook and loop fasteners suffer from limitations such as limited connection strength, poor fatigue resistance, susceptibility to fraying and pilling, and poor environmental adaptability. The root cause lies in the failure to comprehensively improve the hook toughness, the connection strength between the hook and the base fabric, and the surface physicochemical properties of the loop fibers from a systemic perspective of the synergistic effect of the hook and loop surfaces. Therefore, developing a novel hook and loop fastener and its manufacturing process that can significantly improve connection strength, fatigue resistance, and service life without significantly increasing costs has become a pressing technical problem in this field. Summary of the Invention

[0008] The purpose of this invention is to provide a high-strength hook and loop fastener and its manufacturing process to solve the problems in the background art.

[0009] The objective of this invention can be achieved through the following technical solutions: A manufacturing process for high-strength hook and loop fasteners includes the following steps: S1. Preparation of hook face: Preparation of S11 hook-face base fabric: Polyester fiber and low melting point polyester staple fiber are opened and mixed, formed into a web by a carding machine, then pre-needled, and finally hot rolled and shaped on a hot rolling mill to obtain hook-face base fabric; S12 Hook Tooth Molding: After drying the composite thermoplastic polyester elastomer at 80-90℃ for 4-6 hours, it is added to the injection unit of the injection hook molding equipment for melting and plasticizing. The melt is injected into the mold cavity of the forming roller. At the same time, the hook face base fabric is tightly attached to the surface of the forming roller and moves synchronously under tension. The melt in the mold cavity penetrates the surface fiber of the hook face base fabric and fully fuses with the low melting point polyester staple fiber therein. After cooling and shaping, a hook tooth array is formed, and the hook face semi-finished product is obtained by winding. S2. Preparation of the textured surface: S21 Surface treatment of fabric fibers: After plasma treatment, polyamide fibers are immersed in an aqueous dispersion of chitosan microspheres, rolled and dried at 80-100℃, and finally heat-treated at 120-140℃ for 5-15 minutes to crosslink and solidify the chitosan microspheres with the surface of the polyamide fibers. S22 Terry Cloth Planting and Cutting: Surface-treated polyamide fibers are planted on the napped base fabric using a knitting machine to form a uniform terry cloth layer. Then, the top of the terry cloth is neatly cut using a cutting device to form a napped fiber cluster, resulting in a napped semi-finished product. S3, Post-processing: The hook-side and loop-side semi-finished products are cleaned, shaped, and finally cut and rolled up to obtain high-strength hook and loop fasteners.

[0010] Furthermore, the mass percentage of polyester fiber and low-melting-point polyester staple fiber in the hook-face base fabric is 85-95%:5-15%; the melting point of the low-melting-point polyester staple fiber is 110-130℃. During the hook injection molding process, the high-temperature molten elastomer not only adheres to the surface of the base fabric but also penetrates into the fiber gaps. Subsequently, the low-melting-point polyester staple fiber in the base fabric melts upon heating, fusing together with the penetrated elastomer and the surrounding polyester fibers, forming a robust "anchoring" structure upon cooling. This greatly enhances the bonding force between the hook and the base fabric, effectively preventing the hook from being pulled off from its root under stress.

[0011] Furthermore, the hot rolling and shaping temperature is 130-150℃, and the pressure is 2-5MPa.

[0012] Furthermore, the composite thermoplastic polyester elastomer is composed of 60-80 wt% polybutylene terephthalate (PBT) hard segments and 20-40 wt% polyethylene terephthalate (PET) soft segments; the melt index of the composite thermoplastic polyester elastomer is 15-35 g / 10 min. The PBT hard segments provide the necessary rigidity and shape retention, while the PET soft segments endow the material with excellent toughness and fatigue resistance. This "rigid-flexible" structure allows the hook teeth to undergo moderate elastic deformation under tensile force, thereby dispersing stress and avoiding brittle fracture caused by stress concentration. Simultaneously, it can return to its original shape after repeated bending, greatly improving the durability of the hook teeth.

[0013] Furthermore, the hook tooth pattern on the forming roller can be any one of mushroom head shape, J shape, and palm tree shape.

[0014] Furthermore, the injection temperature is 240-260℃, the injection pressure is 60-90MPa, and the holding time is 3-8s.

[0015] Furthermore, the plasma treatment involves using a low-temperature air plasma device at a power of 500-1500W for 30-120 seconds. By bombarding the fiber surface with low-temperature air plasma, the surface can be cleaned and oil stains introduced during processing can be removed. On the other hand, polar functional groups (such as -COOH, -OH) can be introduced into the fiber surface and tiny etching pits can be generated, increasing surface roughness and chemical activity.

[0016] Furthermore, the concentration of chitosan microspheres in the aqueous dispersion is 0.5-2 wt%, and the particle size of the chitosan microspheres is 0.5-5 μm. The chitosan microspheres are firmly attached to the plasma-activated fiber surface through an impregnation-crosslinking process. These chitosan microspheres form a durable, micro-nano composite texture on the fiber surface, significantly increasing the coefficient of friction. When the hooks contact the treated napped fibers, stronger mechanical engagement and van der Waals forces are generated, thereby greatly improving the hook strength.

[0017] Furthermore, the chitosan microsphere aqueous dispersion also contains glutaraldehyde, accounting for 1-3% of the mass of the chitosan microspheres, as a crosslinking agent.

[0018] A high-strength hook and loop fastener, comprising a hook side and a loop side, is prepared by the above-described manufacturing process.

[0019] Beneficial effects Compared with the prior art, the high-strength hook and loop fastener and its manufacturing process provided by the present invention have the following significant advantages: 1. Significantly Improved Connection Strength: Due to the high toughness of the hook material and its strong anchoring to the base fabric, as well as the high friction surface of the napped fibers, the effective contact points and forces between the hook and napped surfaces are greatly enhanced. Test results show that the peel strength and shear strength of the hook and loop fastener of this invention are more than 50% higher than those of traditional nylon hook and loop fasteners.

[0020] 2. Excellent fatigue resistance: The excellent resistance to repeated bending of the composite thermoplastic polyester elastomer hook teeth, as well as the enhanced anti-pilling and anti-snagging ability of the napped fiber due to surface modification, enable the Velcro of this invention to maintain a connection strength retention rate of over 85% after 10,000 repeated opening and closing tests, far exceeding traditional products and greatly extending its service life.

[0021] 3. Good environmental adaptability: Polyester materials are inherently more hydrophobic than nylon, and the hooks are less prone to softening due to moisture absorption. The chitosan microsphere layer on the surface of the napped fibers also has a certain degree of hydrophobicity and chemical stability, allowing the hook and loop fasteners to maintain good connection performance even in humid or slightly oily environments.

[0022] 4. High cost-effectiveness: The composite thermoplastic polyester elastomer, low-melting-point polyester staple fiber, chitosan, and other raw materials used in this invention are all common industrial raw materials, widely available, and moderately priced. The preparation process does not require expensive equipment, and the overall cost is comparable to that of high-end traditional hook and loop fasteners, but the performance far exceeds the latter, resulting in extremely high cost-effectiveness and market competitiveness. Detailed Implementation

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention. Example 1

[0024] This embodiment provides a high-strength hook and loop fastener, including a hook side and a loop side, and its manufacturing process is as follows: S1. Preparation of hook face: Preparation of S11 hook-and-loop base fabric: 85 wt% conventional polyester fiber and 15 wt% low-melting-point polyester staple fiber with a melting point of 110℃ are opened and mixed, formed into a web by a carding machine, then pre-needled, and finally hot-rolled and shaped at 130℃ and 2MPa on a hot rolling mill to obtain a basis weight of 120 g / m². 2 Hook-face base fabric; S12 Hook Molding: A composite thermoplastic polyester elastomer composed of 60wt% PBT hard segments and 40wt% PET soft segments is dried at 80℃ for 6 hours and then added to the injection unit of the injection molding equipment for melting and plasticizing. The melt is injected into the mold cavity with a mushroom-shaped molding roller. The injection temperature is 240℃, the injection pressure is 60MPa, and the holding time is 3s. At the same time, the hook base fabric is tightly attached to the surface of the molding roller and moves synchronously under tension. The melt in the mold cavity penetrates the surface fibers of the hook base fabric and fully fuses with the low melting point polyester staple fibers therein. It is then forcibly cooled to below 40℃ by a cooling roller to form a hook array. The hook semi-finished product is then obtained by winding. S2. Preparation of the textured surface: S21 Surface Treatment of Wool Fiber: Nylon 6 filaments (100D / 36F) were treated for 120s at 500W using a low-temperature air plasma device; a 0.5wt% chitosan microsphere aqueous dispersion was prepared using chitosan microspheres with an average particle size of 0.5μm, and 1% glutaraldehyde was added as a crosslinking agent. The plasma-treated nylon filaments were then immersed in the above chitosan microsphere aqueous dispersion, and the liquid retention rate was controlled to 80% by rollers before drying at 80℃. Finally, the filaments were heat-treated at 120℃ for 15min. S22 Loop Planting and Cutting: Surface-treated nylon filaments are planted on polyester woven napped base fabric through a knitting machine to form a uniform loop layer. Then, the top of the loop is neatly cut using a cutting device to form a napped fiber cluster with a height of about 2mm, resulting in a napped semi-finished product. S3, Post-processing: The hook and loop semi-finished products are cleaned, shaped, and finally cut into standard specifications of 25mm width, then rolled up to obtain high-strength hook and loop fasteners. Example 2

[0025] This embodiment provides a high-strength hook and loop fastener, including a hook side and a loop side, and its manufacturing process is as follows: S1. Preparation of hook face: Preparation of S11 hook-and-loop base fabric: 90 wt% conventional polyester fiber and 10 wt% low-melting-point polyester staple fiber with a melting point of 120℃ are opened and mixed, formed into a web by a carding machine, then pre-needled, and finally hot-rolled and shaped on a hot rolling mill at 140℃ and 3.5 MPa to obtain a basis weight of 120 g / m². 2 Hook-face base fabric; S12 Hook Tooth Molding: A composite thermoplastic polyester elastomer composed of 70wt% PBT hard segments and 30wt% PET soft segments is dried at 85℃ for 5 hours and then added to the injection unit of the injection molding equipment for melting and plasticizing. The melt is injected into the mold cavity with a J-shaped forming roller. The injection temperature is 250℃, the injection pressure is 75MPa, and the holding time is 5s. At the same time, the hook face base fabric is tightly attached to the surface of the forming roller and moves synchronously under tension. The melt in the mold cavity penetrates the surface fiber of the hook face base fabric and fully fuses with the low melting point polyester staple fiber therein. It is then forcibly cooled to below 40℃ by a cooling roller to form a hook tooth array. The hook face semi-finished product is then obtained by winding. S2. Preparation of the textured surface: S21 Surface Treatment of Wool Fiber: Nylon 6 filaments (100D / 36F) were treated for 75s at 1000W using a low-temperature air plasma device; a 1wt% chitosan microsphere aqueous dispersion was prepared using chitosan microspheres with an average particle size of 2μm, and glutaraldehyde (2% by mass of chitosan microspheres) was added as a crosslinking agent. The plasma-treated nylon filaments were then immersed in the above chitosan microsphere aqueous dispersion, and the liquid retention rate was controlled to 80% by rollers before drying at 90℃. Finally, the filaments were heat-treated at 130℃ for 10min. S22 Loop Planting and Cutting: Surface-treated nylon filaments are planted on polyester woven napped base fabric through a knitting machine to form a uniform loop layer. Then, the top of the loop is neatly cut using a cutting device to form a napped fiber cluster with a height of about 2mm, resulting in a napped semi-finished product. S3, Post-processing: The hook and loop semi-finished products are cleaned, shaped, and finally cut into standard specifications of 25mm width, then rolled up to obtain high-strength hook and loop fasteners. Example 3

[0026] This embodiment provides a high-strength hook and loop fastener, including a hook side and a loop side, and its manufacturing process is as follows: S1. Preparation of hook face: Preparation of S11 hook-and-loop base fabric: 95 wt% conventional polyester fiber and 5 wt% low-melting-point polyester staple fiber with a melting point of 130℃ are opened and mixed, formed into a web by a carding machine, then pre-needled, and finally hot-rolled and shaped at 150℃ and 5MPa on a hot rolling mill to obtain a basis weight of 120 g / m². 2 Hook-face base fabric; S12 Hook Molding: A composite thermoplastic polyester elastomer composed of 80wt% PBT hard segments and 20wt% PET soft segments is dried at 90℃ for 4 hours and then added to the injection unit of the injection molding equipment for melting and plasticizing. The melt is injected into the mold cavity with a palm tree-shaped molding roller. The injection temperature is 260℃, the injection pressure is 90MPa, and the holding time is 8s. At the same time, the hook face base fabric is tightly attached to the surface of the molding roller and moves synchronously under tension. The melt in the mold cavity penetrates the surface fibers of the hook face base fabric and fully fuses with the low melting point polyester staple fibers therein. It is then forcibly cooled to below 40℃ by a cooling roller to form a hook tooth array. The hook face semi-finished product is then obtained by winding. S2. Preparation of the textured surface: S21 Surface Treatment of Wool Fiber: Nylon 6 filaments (100D / 36F) were treated for 30 seconds at 1500W using a low-temperature air plasma device; a 2wt% chitosan microsphere aqueous dispersion was prepared using chitosan microspheres with an average particle size of 5μm, and 3% glutaraldehyde was added as a crosslinking agent. The plasma-treated nylon filaments were then immersed in the above chitosan microsphere aqueous dispersion, and the liquid retention rate was controlled to be 80% by rollers before drying at 100℃. Finally, the filaments were heat-treated at 140℃ for 5 minutes. S22 Loop Planting and Cutting: Surface-treated nylon filaments are planted on polyester woven napped base fabric through a knitting machine to form a uniform loop layer. Then, the top of the loop is neatly cut using a cutting device to form a napped fiber cluster with a height of about 2mm, resulting in a napped semi-finished product. S3, Post-processing: The hook and loop semi-finished products are cleaned, shaped, and finally cut into standard specifications of 25mm width, then rolled up to obtain high-strength hook and loop fasteners.

[0027] Comparative Example 1 This comparative example is a traditional nylon hook and loop fastener, using 100wt% nylon 66 injection-molded hook teeth. The hook surface base fabric is a conventional polyester woven fabric, and the loop side is made of untreated nylon filaments implanted on the polyester woven fabric. The manufacturing process follows the conventional hook and loop fastener production method.

[0028] Comparative Example 2 The difference between this comparative example and Example 2 is that the surface treatment process of the wool fiber in step S21 is not performed. Untreated nylon filaments are used for loop planting and cutting. All other raw materials and steps are the same.

[0029] Comparative Example 3 The difference between this comparative example and Example 2 is that it uses conventional nylon hook teeth and conventional polyester hook face base fabric, while the other raw materials and steps are the same.

[0030] The performance of the Velcro prepared in Examples 1-3 and Comparative Examples 1-3 was tested according to the following test methods: Peel strength test: Referring to standard ASTM D5170, 25mm wide hook and napped samples were peeled at a speed of 300mm / min at a 90° angle. The maximum force during the peeling process was recorded, and the peel strength per unit width (N / 25mm) was calculated. Each sample was tested 5 times and the average value was taken.

[0031] Shear strength test: Referring to standard ASTM D5169, a 25mm × 100mm hook and napped sample with an effective contact area of ​​25mm × 25mm was applied with a tensile force parallel to the contact surface at a speed of 300mm / min. The maximum force (N) at separation was recorded. Each sample was tested 5 times and the average value was taken.

[0032] Repeated opening and closing resistance test: Referring to standard ASTM D5170, a dedicated fatigue testing machine was used to subject the glued Velcro sample to continuous peel-and-apply cycles (frequency 20 times / min). After 10,000 cycles, the peel strength was tested again, and the strength retention rate was calculated as (strength after cycles / initial strength × 100%).

[0033] Hook pull-out force test: Randomly select 10 hooks and use a micro force testing machine to measure the force required to vertically pull them out of the base fabric, and take the average value (cN).

[0034] The test results are shown in Table 1: Table 1 As can be seen from the data in Table 1, the hook and loop fasteners prepared in Examples 1-3 are significantly better than the traditional nylon hook and loop fasteners in Comparative Example 1 in terms of initial peel strength, shear strength, fatigue resistance and hook pull-out force. As can be seen from Comparative Examples 2 and 3, improving only the hook surface or the loop surface has limited effect on improving the peel strength and shear strength of the hook and loop fasteners. Only by improving the hook surface and the loop surface in synergy in this invention can a stable and comprehensive improvement in the connection strength, durability and reliability of the hook and loop fasteners be achieved.

[0035] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0036] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A manufacturing process for high-strength hook and loop fasteners, characterized in that, Includes the following steps: S1. Preparation of hook face: S11: Polyester fiber and low melting point polyester staple fiber are opened and mixed, formed into a web by a carding machine, then pre-needled, and finally hot rolled and shaped on a hot rolling mill to obtain hook-face base fabric. S12: After drying the composite thermoplastic polyester elastomer, it is added to the injection molding unit for melting and plasticizing. The melt is injected into the mold cavity of the forming roller and then anchored on the surface of the hook base fabric that moves synchronously with the forming roller. After cooling and shaping, a hook tooth array is formed and the hook semi-finished product is obtained by winding. S2. Preparation of the textured surface: S21: After plasma treatment, polyamide fibers are impregnated in an aqueous dispersion of chitosan microspheres, rolled and dried, and finally heat-treated at 120-140℃ for 5-15 minutes. S22: The surface-treated polyamide fibers are implanted onto the napped base fabric through a knitting machine to form a loop layer. The loop layer is then cut to form a napped fiber cluster, resulting in a napped semi-finished product. S3, Post-processing: The hook-side and loop-side semi-finished products are cleaned, shaped, and finally cut and rolled up to obtain high-strength hook and loop fasteners.

2. The manufacturing process of a high-strength hook and loop fastener according to claim 1, characterized in that, The mass percentage of polyester fiber and low-melting-point polyester staple fiber in the hook-and-face base fabric is 85-95%: 5-15%; the melting point of the low-melting-point polyester staple fiber is 110-130℃.

3. The manufacturing process of a high-strength hook and loop fastener according to claim 1, characterized in that, The hot rolling and shaping temperature is 130-150℃, and the pressure is 2-5MPa.

4. The manufacturing process of a high-strength hook and loop fastener according to claim 1, characterized in that, The composite thermoplastic polyester elastomer is composed of 60-80 wt% polybutylene terephthalate and 20-40 wt% polyethylene terephthalate; the melt index of the composite thermoplastic polyester elastomer is 15-35 g / 10 min.

5. The manufacturing process of a high-strength hook and loop fastener according to claim 1, characterized in that, The hook tooth pattern on the forming roller can be any one of mushroom head shape, J shape, and palm tree shape.

6. The manufacturing process of a high-strength hook and loop fastener according to claim 1, characterized in that, The injection temperature is 240-260℃, the injection pressure is 60-90MPa, and the holding time is 3-8s.

7. The manufacturing process of a high-strength hook and loop fastener according to claim 1, characterized in that, The plasma treatment is performed by using a low-temperature air plasma device at a power of 500-1500W for 30-120 seconds.

8. The manufacturing process of a high-strength hook and loop fastener according to claim 1, characterized in that, The concentration of chitosan microspheres in the aqueous dispersion is 0.5-2 wt%, and the particle size of the chitosan microspheres is 0.5-5 μm.

9. The manufacturing process of a high-strength hook and loop fastener according to claim 8, characterized in that, The chitosan microsphere aqueous dispersion also contains glutaraldehyde, accounting for 1-3% of the mass of the chitosan microspheres, as a crosslinking agent.

10. A high-strength hook and loop fastener, comprising a hook side and a loop side, characterized in that, It is prepared by the preparation process described in any one of claims 1-9.

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