Sandwich structure fabric and weaving method thereof

Abstract

The present invention belongs to the technical field of knitted fabrics and specifically provides a sandwich-structured fabric and a knitting method thereof, comprising a surface functional layer, an intermediate support layer, and a bottom contact layer, arranged sequentially from top to bottom; the surface functional layer is a plain weft-knitted coil layer with a thickness of 0.18-0.22 mm; the intermediate support layer is a periodic hexagonal honeycomb structure layer with a thickness of 0.85-1.20 mm and a single cell side length of 1.5-1.8 mm; the bottom contact layer is a plain weft-knitted coil layer with a thickness of 0.15-0.18 mm; and the connecting yarn system is a connecting yarn system composed of elastic multifilament yarns that simultaneously connect the surface functional layer, the intermediate support layer, and the bottom contact layer in an intermittently threaded manner. This application utilizes a precisely controlled sandwich structure design, a spatial V-shaped anchoring system, and a synchronous knitting process to simultaneously achieve improved compressive resilience, full-band UV protection, and long-lasting skin-friendly properties in a single molding process.

Description

Technical Field

[0001] The invention belongs to the technical field of knitted fabrics, and particularly relates to a sandwich structure fabric and a knitting method thereof. Background Art

[0002] Sandwich knitted fabrics are three-dimensional structures formed by a surface functional layer, an intermediate support layer, and a bottom contact layer connected by a yarn system. The interlayer connection method is the core factor that determines the product's functionality. In sports insoles, they must provide cushioning and rebound under a pressure of five newtons per square centimeter. In medical bandages, they must conduct sweat at a rate of over eight kilograms per square meter per day. In outdoor clothing, the interlayer bond strength must remain above 15 newtons per five centimeters after 50 standard washes. However, currently available products suffer from three key flaws.

[0003] First, a serious lack of compression resilience has become a pain point in the industry. The polyurethane foam middle layer used in typical sports kneepads shrinks from an initial thickness of eight millimeters to approximately four millimeters after 5,000 standard compression tests, a thickness loss exceeding 50%, causing rapid functional failure. Existing solutions generally use hot-melt adhesive to bond the reinforcement layer. While this method limits the compression thickness loss to less than 25%, it causes the fabric's air permeability to plummet from 3,500 liters per square meter per second to 1,200 liters per square meter per second, failing to meet the ventilation requirements of high-intensity exercise.

[0004] Secondly, moisture conduction blockage is a prominent issue. When sweating during intense exercise, it accumulates between the hydrophobic polyester surface layer and the hydrophilic cotton fiber bottom layer, forming a middle layer of condensed water. Test data shows that after 30 minutes of use at 38 degrees Celsius and 90 percent relative humidity, the moisture content of this middle layer reaches 29 percent, creating a breeding ground for bacteria. Existing improved technology increases moisture permeability by creating micropores with a diameter of 0.8 mm in the surface layer. While this solution increases moisture permeability to 9,500 grams per square meter per day, the longitudinal and transverse breaking strength of the fabric at the micropores decreases by over 35 percent, significantly shortening the product's lifespan.

[0005] Finally, interlayer structure separation remains a long-standing issue. Traditional double-needle-bar warp-knitted fabrics, with interlayer connecting yarns comprising less than 6%, experience a drop in interlayer peel strength from an initial value of 22 Newtons per five centimeters to 9 Newtons per five centimeters after 50 standard wash cycles. While the latest bonding technology, which uses a meltblown method to deposit a polyamide bonding layer between layers, maintains a peel strength of 18 Newtons per five centimeters, it increases the fabric's bending stiffness to 120 millinewtons per centimeter, compromising the ergonomically desirable flexibility and fit.

[0006] The core contradiction revealed by existing technologies lies in the fact that enhancing structural stability inevitably sacrifices breathability and moisture permeability, while improving moisture conductivity inevitably weakens mechanical strength. Separate manufacturing processes are unable to overcome these mutually restrictive performance bottlenecks. Therefore, it is necessary to design a sandwich structure fabric and its weaving method. Summary of the Invention

[0007] In order to overcome the defects in the prior art, a sandwich structure fabric and a weaving method thereof are provided.

[0008] In order to achieve the above object, the present invention provides the following technical solutions:

[0009] A sandwich structure fabric comprises a surface functional layer, an intermediate support layer and a bottom contact layer, which are sequentially distributed from top to bottom. The surface functional layer, the intermediate support layer and the bottom contact layer are connected into one by a connecting yarn system. The surface functional layer is a plain weft-knitted coil layer with a thickness of 0.18-0.22 mm. The intermediate support layer is a periodic hexagonal honeycomb structure layer with a thickness of 0.85-1.20 mm and a single cell side length of 1.5-1.8 mm. The bottom contact layer is a plain weft-knitted coil layer with a thickness of 0.15-0.18 mm. The connecting yarn system comprises elastic multifilament yarns that are threaded at intervals to simultaneously connect the surface functional layer, the intermediate support layer and the bottom contact layer.

[0010] Preferably, the periodic hexagonal honeycomb structure layer is composed of periodically arranged basic hexagonal units, and the inner side length of a single basic hexagonal unit is 1.5-1.8 mm.

[0011] Preferably, the elastic multifilament yarn of the connecting yarn system penetrates from the surface functional layer, extends to the geometric center point of the basic hexagonal unit, bends 110°-120°, and then penetrates to the bottom contact layer to form a spatial V-shaped anchoring structure.

[0012] Preferably, the distance between the geometric center points of the basic hexagonal units is 3.2-3.8 mm, and the deviation of the overlap between the vertices of the spatial V-shaped anchoring structure and the geometric center points is ≤0.1 mm.

[0013] Preferably, the extension path of the connecting yarn system in the middle support layer is: from the vertex of the side wall of the basic hexagonal unit to the interior of the basic hexagonal unit, extending along the diagonal of the basic hexagonal unit to the geometric center point, bending at the geometric center point and extending along the diagonal of the adjacent basic hexagonal unit to the vertex of the side wall and out.

[0014] Preferably, the material of the surface functional layer is UV-shielding modified polyester filament, and its preparation method includes the following steps: treating TiO2 with a particle size of 25-40nm and KH550 silane coupling agent in a mass ratio of 1:(0.8-1.2) at 75-85°C for 40-50min to obtain modified TiO2, and then melt-melting the modified TiO2 with PET in a ratio of 100:(1-1.5), spinning at 270-280°C and 12-15MPa, and then stretching at 3200-3500m / min to obtain UV-shielding modified polyester filament.

[0015] Preferably, the bottom contact layer is made of core-sheath composite fiber, wherein the core layer material of the core-sheath composite fiber is polypropylene with a melt index of 35-40 g / 10min, and the skin layer material of the core-sheath composite fiber is PEG-PET copolyester.

[0016] Preferably, the preparation method of PEG-PET copolyester is: mixing polyethylene glycol with a molecular weight of 3000-3500 with purified terephthalic acid and ethylene glycol in a molar ratio of 1:(1.2-1.6):(0.4-0.6); adding 0.03-0.05wt% ethylene glycol antimony catalyst, and the esterification temperature is 240-245°C; raising the temperature to 250-255°C in the polycondensation stage, the vacuum degree is less than 50Pa, the reaction time is 120-150min, and pelletizing to obtain PEG-PET copolyester.

[0017] Preferably, the elastic multifilament yarn is composed of a spandex core yarn and a polyetherester covering yarn, the spandex core yarn has a fineness of 20-30D, the polyetherester covering yarn has a fineness of 40-60D, the covering twist is 950-1100 twists / m, and the spandex core yarn accounts for 35%-40% of the elastic multifilament yarn.

[0018] The present invention also provides a method for weaving a sandwich structure fabric, which is performed using a double-sided circular knitting machine equipped with a surface needle system, a connecting needle system, and a bottom needle system, and includes the following steps:

[0019] a. Surface functional layer weaving:

[0020] The needle system hooks the UV-shielding modified polyester filament to form a plain weft knitted coil layer on the needle disc with a loop density of 48-52 loops / inch and a yarn feeding tension of 4.8-5.2 cN, which is the surface functional layer;

[0021] b. Construction of the intermediate support layer:

[0022] The watch needle system and the bottom needle system work together to form a periodic hexagonal honeycomb structure layer. The periodic hexagonal honeycomb structure layer is composed of periodically arranged basic hexagonal units. The inner side length of the basic hexagonal unit is 1.5-1.8mm, and the geometric center point spacing of the basic hexagonal unit is 3.2-3.8mm, which is the middle support layer.

[0023] c. Braided bottom contact layer:

[0024] The bottom needle system hooks the core-skin composite fiber and forms a plain weft knitted coil layer on the needle cylinder with a loop density of 58-62 turns / inch and a yarn feeding tension of 5.0-5.5 cN, which is the bottom contact layer.

[0025] d. Formation of spatial V-shaped anchoring structure:

[0026] The connecting needle system performs the yarn threading action: the needle is inserted from the coil of the surface functional layer, the puncture point is positioned at the side wall vertex of the basic hexagonal unit of the middle support layer, and extends along the diagonal of the basic hexagonal unit to the geometric center point. After bending 110°-120° at the geometric center point, it extends along the diagonal of the adjacent basic hexagonal unit to the side wall vertex and then passes through, and then connects the coil of the bottom contact layer to form a spatial V-shaped anchoring structure. The result is a sandwich structure fabric.

[0027] Compared with the prior art, the advantages and beneficial effects of the present invention are:

[0028] 1. This invention significantly improves the overall performance of sandwich fabrics through its innovative structural design. The intermediate support layer utilizes a periodic hexagonal honeycomb structure, combined with the elastic multifilament yarns of the connecting yarn system, which are connected in a spatial V-shaped anchoring pattern, forming a stable yet resilient overall framework. This design evenly distributes stress when under pressure and quickly recovers to its original shape, avoiding the sudden drop in air permeability caused by existing hot-melt adhesive bonding. This improves the product's compression resilience while maintaining high air permeability.

[0029] 2. This invention achieves a breakthrough in moisture vapor conduction, primarily due to the core-skin composite fiber material of the bottom contact layer. The hydrophilic skin layer efficiently absorbs sweat, and this synergistically combines with the hydrophobic properties of the surface functional layer and the open structure of the intermediate honeycomb layer to allow moisture to be smoothly conducted through the interlayer spaces. This mechanism overcomes the reduction in fabric strength associated with existing microporous technology, as the connecting yarn system does not block the moisture path, maintaining intact mechanical strength.

[0030] 3. This invention significantly enhances interlayer bond strength thanks to the precise V-shaped anchoring structure formed by the connecting yarn system. Its apex is precisely positioned at the geometric center of the basic hexagonal unit with minimal deviation, ensuring a secure connection. The knitting process is integrated, with the connecting needle system directly threading the yarns from three layers to form the overall structure. This ensures stable peel strength after washing while preventing increased bending stiffness and maintaining the flexible fit required by the human body.

[0031] 4. This invention balances various performance parameters, such as air and moisture permeability, mechanical strength, and structural stability, overcoming the performance limitations of existing separate manufacturing processes. The entire design utilizes a one-piece weaving method, achieving seamless integration of all functional layers. This resolves the inherent conflict between enhancing stability and maintaining air and moisture permeability, thereby improving the overall performance of the product. DETAILED DESCRIPTION

[0032] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0033] In this application, the sources of various raw materials are briefly described as follows:

[0034] Nano-titanium dioxide (TiO2) was VK-T30H from Jiangsu Tianxing New Materials Co., Ltd.; KH550 silane coupling agent was ND-550 from Hubei New Blue Sky New Materials Co., Ltd.; PET chips were YSC-800 from Zhejiang Rongsheng Petrochemical Co., Ltd.; polypropylene was EP548R from Sinopec Maoming Branch, with a melt index of 35-40g / 10min; polyethylene glycol was PEG-3350 from Jiangsu Dena Chemical Co., Ltd., with a molecular weight of 3000-3500; purified terephthalic acid was PTA-FB-08 from Hengli Petrochemical; ethylene glycol was high-purity MEG-FG01 from Sinopec Shanghai Petrochemical; the catalyst was XY-03 antimony glycol from Hunan Xinyuan New Materials, with an antimony content of at least 55.8%; and the spandex core yarn was Creora® from Hyosung Spandex Jiaxing Co., Ltd. CT-30D product, fineness 20-30D; polyetherester covered wire is selected from the PBT-403 specification of Yantai Taihe New Materials Co., Ltd., with a fineness range of 40-60D.

[0035] A sandwich structure fabric comprises a surface functional layer, an intermediate support layer and a bottom contact layer, which are sequentially distributed from top to bottom. The surface functional layer, the intermediate support layer and the bottom contact layer are connected into one by a connecting yarn system. The surface functional layer is a plain weft-knitted coil layer with a thickness of 0.18-0.22 mm. The intermediate support layer is a periodic hexagonal honeycomb structure layer with a thickness of 0.85-1.20 mm and a single cell side length of 1.5-1.8 mm. The bottom contact layer is a plain weft-knitted coil layer with a thickness of 0.15-0.18 mm. The connecting yarn system comprises elastic multifilament yarns that are threaded at intervals to simultaneously connect the surface functional layer, the intermediate support layer and the bottom contact layer.

[0036] The elastic multifilament yarn of the connecting yarn system penetrates from the surface functional layer, extends to the geometric center point of the basic hexagonal unit, bends 110°-120°, and then penetrates to the bottom contact layer to form a spatial V-shaped anchoring structure.

[0037] The geometric center point spacing of the basic hexagonal unit is 3.2-3.8 mm, and the coincidence deviation between the vertices of the spatial V-shaped anchoring structure and the geometric center point is ≤0.1 mm.

[0038] The extension path of the connecting yarn system in the middle support layer is: from the vertex of the side wall of the basic hexagonal unit, it penetrates into the interior of the basic hexagonal unit, extends along the diagonal of the basic hexagonal unit to the geometric center point, bends at the geometric center point, and then extends along the diagonal of the adjacent basic hexagonal unit to the vertex of the side wall and passes out.

[0039] The material of the surface functional layer adopts ultraviolet shielding modified polyester filament, and its preparation method includes the following steps: TiO2 with a particle size of 25-40nm and KH550 silane coupling agent are treated at a mass ratio of 1: (0.8-1.2) at 75-85℃ for 40-50min to obtain modified TiO2, and then the modified TiO2 is melt-mixed with PET at a mass ratio of 100: (1-1.5), spinning at 270-280℃ and 12-15MPa, and then drawing at 3200-3500m / min to obtain ultraviolet shielding modified polyester filament.

[0040] The material of the bottom contact layer is core-sheath composite fiber, wherein the core layer material of the core-sheath composite fiber is polypropylene with a melt index of 35-40g / 10min, and the skin layer material of the core-sheath composite fiber is PEG-PET copolyester.

[0041] The preparation method of PEG-PET copolyester comprises: mixing polyethylene glycol with a molecular weight of 3000-3500 with purified terephthalic acid and ethylene glycol in a molar ratio of 1:(1.2-1.6):(0.4-0.6); adding 0.03-0.05 wt% of ethylene glycol antimony catalyst, and esterification temperature of 240-245° C.; raising the temperature to 250-255° C. in the polycondensation stage, with a vacuum degree of less than 50 Pa, a reaction time of 120-150 minutes, and pelletizing to obtain the PEG-PET copolyester.

[0042] The elastic multifilament yarn is composed of spandex core yarn and polyetherester covering yarn. The spandex core yarn fineness is 20-30D, the polyetherester covering yarn fineness is 40-60D, the covering twist is 950-1100 twists / m, and the spandex core yarn mass accounts for 35%-40% of the elastic multifilament yarn.

[0043] A method for weaving a sandwich structure fabric is provided, which is performed using a double-sided circular knitting machine equipped with a surface needle system, a connecting needle system, and a bottom needle system, and comprises the following steps:

[0044] a. Surface functional layer weaving:

[0045] The needle system hooks the UV-shielding modified polyester filament to form a plain weft knitted coil layer on the needle disc with a loop density of 48-52 loops / inch and a yarn feeding tension of 4.8-5.2 cN, which is the surface functional layer;

[0046] b. Construction of the intermediate support layer:

[0047] The watch needle system and the bottom needle system work together to form a periodic hexagonal honeycomb structure layer. The periodic hexagonal honeycomb structure layer is composed of periodically arranged basic hexagonal units. The inner side length of the basic hexagonal unit is 1.5-1.8mm, and the geometric center point spacing of the basic hexagonal unit is 3.2-3.8mm, which is the middle support layer.

[0048] c. Braided bottom contact layer:

[0049] The bottom needle system hooks the core-skin composite fiber and forms a plain weft knitted coil layer on the needle cylinder with a loop density of 58-62 turns / inch and a yarn feeding tension of 5.0-5.5 cN, which is the bottom contact layer.

[0050] d. Formation of spatial V-shaped anchoring structure:

[0051] The connecting needle system performs the yarn threading action: the needle is inserted from the coil of the surface functional layer, the puncture point is positioned at the side wall vertex of the basic hexagonal unit of the middle support layer, and extends along the diagonal line of the basic hexagonal unit to the geometric center point. After bending 110°-120° at the geometric center point (forming a spatial V-shaped turn), it extends along the diagonal line of the adjacent basic hexagonal unit to the side wall vertex and then passes through, and then connects the coil of the bottom contact layer to form a spatial V-shaped anchoring structure. The result is a sandwich structure fabric.

[0052] The advantages of this application are concentrated in the synergistic effect of three technological innovations: the first is the precision of the structural design. The surface functional layer adopts a plain weft knitted structure with a thickness of 0.18-0.22 mm, the middle support layer is a periodic hexagonal honeycomb unit with a single cell side length of 1.5-1.8 mm, and the bottom contact layer is configured with a plain weft knitted layer of 0.15-0.18 mm. The three are precisely positioned in space through a V-shaped anchoring connection system. In this system, the elastic multifilament yarn is bent 110-120 degrees at the geometric center point, and the positioning deviation between the vertex and the center point is strictly controlled within 0.1 mm; the second is the integration of the manufacturing process. The surface needle system, connecting needle system and bottom needle system of the double-sided circular knitting machine are used for synchronous operation. The surface layer is woven with a loop density of 48-52 circles per inch and a loop density of 4 .8-5.2 centinewyn yarn feeding tension forms the functional layer. In the construction of the support layer, the spacing between the geometric center points of the hexagonal units is controlled to be 3.2-3.8 mm. In the weaving of the bottom layer, the contact layer is completed with a loop density of 58-62 turns per inch and a yarn feeding tension of 5.0-5.5 centinewyn; the third is the in-situ function of the material. The surface functional layer is modified by nano-titanium dioxide particles with a diameter of 25-40 nanometers and a silane coupling agent at 75-85 degrees Celsius and then melt-spun with PET to achieve UV protection. The core-skin structure of the bottom layer is composed of a polypropylene core layer with a melt index of 35-40 grams per 10 minutes and a PEG-PET copolyester skin layer. The connecting yarn system is formed by compounding 20-30 denier spandex core yarn and 40-60 denier polyetherester coated yarn with a twist of 950-1100 twists per meter to form an elastic support.

[0053] The technical solution of the present invention is further illustrated by the following examples and comparative examples, but the protection scope of the present invention is not limited thereto.

[0054] Example 1:

[0055] In this example, the fabric parameters are as follows: the surface functional layer utilizes a 0.18mm thick plain weft-knitted coil layer; the UV-shielding modified polyester filament is prepared using a TiO2 particle size of 25nm, a KH550 silane coupling agent to TiO2 mass ratio of 0.8:1, a PET to modified TiO2 ratio of 100:1 during melt mixing, a spinning temperature of 280°C / 15MPa, and a draw speed of 3500m / min. The intermediate support layer has a hexagonal unit cell with a side length of 1.8mm and a geometric center-to-center spacing of 3.8mm; the bottom contact layer is 0.18mm thick; the polypropylene melt index in the core-skin composite fiber is 40g / 10min; the PEG-PET copolyester is prepared using a polyethylene glycol molecular weight of 3500 at a molar ratio of 1:1.6:0.6; and the polycondensation temperature is 255°C / 50Pa. The elastic multifilament yarn features a 30D spandex core and a 60D polyetherester covering. The twist is 1100 twists / m, with the spandex core accounting for 40%. During weaving, the surface layer has a loop density of 52 turns / inch and a yarn feed tension of 5.2 cN, while the bottom layer has a loop density of 62 turns / inch and a yarn feed tension of 5.5 cN. The connecting needle puncture point is located at the vertex of the hexagonal wall, with a bend angle of 120°.

[0056] Example 2:

[0057] In this embodiment, the same points as in Example 1 are not described in detail, and the differences are as follows:

[0058] The surface functional layer is 0.22mm thick, the UV-shielding modified TiO2 particle size is 40nm, the KH550 silane coupling agent ratio is 1.2:1, the melt mixing ratio is 100:1.5, the spinning temperature is 270°C / 12MPa, and the draw speed is 3200m / min. The hexagonal sides of the middle layer are 1.5mm long, with a center-to-center spacing of 3.2mm. The bottom contact layer is 0.15mm thick, the polypropylene melt index is 35g / 10min, and the PEG-PET is prepared using polyethylene glycol with a molecular weight of 3000, a molar ratio of 1:1.2:0.4, and a polycondensation temperature of 250°C. The elastic multifilament yarn has a spandex core yarn fineness of 25D, a polyetherester sheath yarn fineness of 50D, a twist of 1050 twists / m, and a spandex core yarn composition of 35%. Weaving parameters: surface loop density 50 loops / inch, yarn feeding tension 4.8 cN, bottom layer density 58 loops / inch, yarn feeding tension 5.3 cN; bending angle 115°.

[0059] Example 3:

[0060] In this embodiment, the same points as in Example 1 are not described in detail, and the differences are as follows:

[0061] The surface layer is 0.20mm thick, with a TiO2 particle size of 32nm. The ratio of KH550 silane coupling agent is 1:1, the melt mixing ratio is 100:1.3, the spinning temperature is 275°C / 13MPa, and the drawing speed is 3350m / min. The hexagonal sides of the middle layer are 1.6mm long, with a center-to-center spacing of 3.5mm. The bottom contact layer is 0.16mm thick, with a polypropylene melt index of 38g / 10min and a PEG-PET molar ratio of 1:1.4:0.5. The elastic multifilament yarn has a spandex core yarn of 20D, a polyetherester sheath yarn of 40D, a twist of 950 twists / m, and a spandex core yarn content of 38%. Weaving parameters: surface loop density 48 turns / inch, yarn feed tension 5.0cN, bottom layer 60 turns / inch, yarn feed tension 5.0cN, and a bending angle of 110°.

[0062] Comparative Example 1:

[0063] In this comparative example, the same points as in Example 1 are not repeated here, and the differences are as follows:

[0064] The middle support layer is made of traditional polyurethane foam layer (thickness 1.2mm, density 0.25g / cm 3 ), the connection method is hot melt adhesive bonding (polyamide adhesive layer thickness 0.1mm).

[0065] Comparative Example 2:

[0066] In this comparative example, the same points as Example 2 are not repeated here, and the differences are as follows:

[0067] The surface functional layer is made of unmodified polyester filaments, and the hexagonal structure of the middle support layer is changed to a rectangular grid.

[0068] Comparative Example 3:

[0069] In this comparative example, the same points as in Example 3 are not repeated here, and the differences are as follows:

[0070] The honeycomb structure of the middle support layer is cancelled and replaced with a double needle bed warp knitted spacer fabric (connecting yarn accounts for 6%).

[0071] Comparative Example 4:

[0072] In this comparative example, the same points as in Example 1 are not repeated here, and the differences are as follows:

[0073] The bottom contact layer removes the core-skin composite fiber and uses a plain weave of pure cotton fiber instead.

[0074] Comparative Example 5:

[0075] The weaving process of Example 2 was adopted, but the bending angle of the connecting yarn was changed to 90°, and the deviation between the vertex and the center point of the hexagon was 0.3 mm.

[0076] Performance test results and analysis:

[0077] The fabrics obtained according to the parameters of the embodiment and the comparative example were tested according to standards such as GB / T 24218. The test results are shown in Table 1.

[0078] Table 1 Analysis and test results

[0079]

[0080] The thickness loss rates of Examples 1-3 were all below 20%, significantly superior to the comparative example. This is attributed to the uniform pressure distribution provided by the hexagonal honeycomb structure and the spatial V-shaped anchoring effect of the elastic multifilament connecting yarn. Comparative Example 1, due to its use of a foam layer and hot melt adhesive, permanently deformed under pressure, demonstrating the compression resilience of the present invention.

[0081] The moisture permeability of Examples 1-3 exceeds 9500 g / m 2 d, a 60% increase over Comparative Example 4. This demonstrates the synergistic hydrophilic / hydrophobic effect of the core-skin fiber: the PEG-PET layer rapidly absorbs sweat, while the honeycomb structure in the middle layer forms continuous moisture-conducting channels. In Comparative Example 2, the surface layer remains unmodified, leading to sweat accumulation on the surface.

[0082] Structural Stability: The interlayer peel strength of the examples reached 23.5-24.7 N / 5cm, maintaining a strength of 22.1-23.8 N / 5cm after 50 washes. However, due to the insufficient proportion of connecting yarn in the traditional warp knitting structure, the strength of Comparative Example 3 decreased to 8.9 N / 5cm. The key design feature is the ≤0.1mm deviation between the V-shaped anchor vertex and the hexagonal center, compared to the 0.3mm deviation in Comparative Example 5.

[0083] Flexibility balance: The bending stiffness of the embodiment is ≤81.2 mN·cm, which is 34% lower than that of comparative example 1. This demonstrates that the spatial V-shaped anchoring strengthens the bond without increasing the stiffness, whereas the hot melt adhesive of comparative example 1 or the angle deviation of comparative example 5 lead to increased stiffness.

[0084] The above implementation methods verify that the technical solution of the present invention successfully solves the three major defects in the background technology and achieves performance breakthroughs through structure-material-process collaborative innovation.

[0085] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A sandwich structure fabric, characterized in that: The surface functional layer comprises a surface functional layer, an intermediate support layer, and a bottom contact layer, which are arranged in sequence from top to bottom. The surface functional layer, the intermediate support layer, and the bottom contact layer are connected into one piece by a connecting yarn system. The surface functional layer is a plain weft-knitted coil layer with a thickness of 0.18-0.22 mm. The intermediate support layer is a periodic hexagonal honeycomb structure layer with a thickness of 0.85-1.20 mm and a single cell side length of 1.5-1.8 mm. The bottom contact layer is a plain weft-knitted coil layer with a thickness of 0.15-0.18 mm. The connecting yarn system is composed of elastic multifilament yarns that are interlaced and connected to the surface functional layer, the intermediate support layer, and the bottom contact layer. The periodic hexagonal honeycomb structure layer is composed of periodically arranged basic hexagonal units, and the inner side length of a single basic hexagonal unit is 1.5-1.8 mm; The elastic multifilament yarn of the connecting yarn system penetrates from the surface functional layer, extends to the geometric center point of the basic hexagonal unit, bends 110°-120°, and then penetrates the bottom contact layer to form a spatial V-shaped anchoring structure; The extension path of the connecting yarn system in the middle supporting layer is: from the vertex of the side wall of the basic hexagonal unit, it penetrates into the interior of the basic hexagonal unit, extends along the diagonal of the basic hexagonal unit to the geometric center point, bends at the geometric center point, and then extends along the diagonal of the adjacent basic hexagonal unit to the vertex of the side wall and passes out.

2. The sandwich structure fabric according to claim 1, characterized in that: The geometric center point spacing of the basic hexagonal unit is 3.2-3.8 mm, and the coincidence deviation between the vertices of the spatial V-shaped anchoring structure and the geometric center point is ≤0.1 mm.

3. The sandwich structure fabric according to claim 1, characterized in that: The material of the surface functional layer is ultraviolet shielding modified polyester filament, and its preparation method includes the following steps: TiO2 with a particle size of 25-40nm and KH550 silane coupling agent are treated at a mass ratio of 1: (0.8-1.2) at 75-85°C for 40-50 minutes to obtain modified TiO2, and then the modified TiO2 is melt-mixed with PET at a mass ratio of 100: (1-1.5), spinning at 270-280°C and 12-15MPa, and then drawing at 3200-3500m / min to obtain ultraviolet shielding modified polyester filament.

4. The sandwich structure fabric according to claim 1, characterized in that: The bottom contact layer is made of core-sheath composite fiber, wherein the core layer material of the core-sheath composite fiber is polypropylene with a melt index of 35-40g / 10min, and the skin layer material of the core-sheath composite fiber is PEG-PET copolyester.

5. The sandwich structure fabric according to claim 4, characterized in that: The preparation method of the PEG-PET copolyester comprises: mixing polyethylene glycol with a molecular weight of 3000-3500 with purified terephthalic acid and ethylene glycol in a molar ratio of 1:(1.2-1.6):(0.4-0.6); adding 0.03-0.05 wt% of ethylene glycol antimony catalyst, and setting an esterification temperature of 240-245° C.; raising the temperature to 250-255° C. in the polycondensation stage, with a vacuum degree of less than 50 Pa, a reaction time of 120-150 minutes, and pelletizing to obtain the PEG-PET copolyester.

6. The sandwich structure fabric according to claim 1, characterized in that: The elastic multifilament yarn is composed of spandex core yarn and polyetherester covering yarn. The spandex core yarn fineness is 20-30D, the polyetherester covering yarn fineness is 40-60D, the covering twist is 950-1100 twists / m, and the spandex core yarn mass accounts for 35%-40% of the elastic multifilament yarn.

7. A method for weaving a sandwich structure fabric, for producing a sandwich structure fabric as claimed in any one of claims 1 to 6, using a double-sided circular knitting machine equipped with a surface needle system, a connecting needle system, and a bottom needle system for weaving, characterized in that: The following steps are involved: a. Surface functional layer weaving: The needle system hooks the UV-shielding modified polyester filament to form a plain weft knitted coil layer on the needle disc with a loop density of 48-52 loops / inch and a yarn feeding tension of 4.8-5.2 cN, which is the surface functional layer; b. Construction of the intermediate support layer: The watch needle system and the bottom needle system work together to form a periodic hexagonal honeycomb structure layer. The periodic hexagonal honeycomb structure layer is composed of periodically arranged basic hexagonal units. The inner side length of the basic hexagonal unit is 1.5-1.8mm, and the geometric center point spacing of the basic hexagonal unit is 3.2-3.8mm, which is the middle support layer. c. Braided bottom contact layer: The bottom needle system hooks the core-skin composite fiber and forms a plain weft knitted coil layer on the needle cylinder with a loop density of 58-62 turns / inch and a yarn feeding tension of 5.0-5.5 cN, which is the bottom contact layer. d. Formation of spatial V-shaped anchoring structure: The connecting needle system performs the yarn threading action: the needle is inserted from the coil of the surface functional layer, the puncture point is positioned at the side wall vertex of the basic hexagonal unit of the middle support layer, and extends along the diagonal of the basic hexagonal unit to the geometric center point. After bending 110°-120° at the geometric center point, it extends along the diagonal of the adjacent basic hexagonal unit to the side wall vertex and then passes through, and then connects the coil of the bottom contact layer to form a spatial V-shaped anchoring structure. The result is a sandwich structure fabric.

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