Sandwich structure fabric and weaving method thereof

Abstract

The invention belongs to the technical field of knitted fabrics, and particularly provides a sandwich structure fabric and a weaving method thereof.The sandwich structure fabric comprises a surface functional layer, a middle supporting layer and a bottom surface contact layer which are sequentially distributed from top to bottom; the surface functional layer is a plain weft knitting coil layer with the thickness of 0.18-0.22 mm; the middle supporting layer is a periodic hexagonal honeycomb structure layer with the thickness of 0.85-1.20 mm, and the side length of a unit cell is 1.5-1.8 mm; the bottom surface contact layer is a plain weft knitting coil layer with the thickness of 0.15-0.18 mm; and the connecting yarn system is formed by simultaneously connecting the surface functional layer, the middle supporting layer and the bottom surface contact layer with elastic multifilament yarns in a spaced penetrating and sleeving manner. Through the precisely controlled sandwich structure design, in cooperation with the spatial V-shaped anchoring system and the synchronous weaving technology, the functions of compression resistance rebound resilience improvement, ultraviolet full-wave-band blocking and long-acting skin-friendly performance are synchronously achieved in one-time forming.

Description

Technical Field

[0001] The present 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] A sandwich structure knitted fabric refers to a three-dimensional integral structure formed by a surface functional layer, an intermediate support layer, and a bottom contact layer through a connecting yarn system. The interlayer connection method is the core element determining the product function. In the application of sports shoe insoles, it is required to provide cushioning and resilience under a pressure of five Newtons per square centimeter. In medical bandages, it is necessary to achieve a sweat conduction capacity of more than eight kilograms per square meter per day. In outdoor clothing, it is required that the interlayer bonding strength remains above fifteen Newtons per five centimeters after fifty standard washes. However, there are three key defects in current commercially available products.

[0003] First of all, the serious lack of compression resilience has become a pain point in the industry. The polyurethane foam intermediate layer used in typical sports knee pads, after 5,000 standard compression tests, the initial thickness is reduced from 8 millimeters to about 4 millimeters, and the thickness loss rate exceeds 50%, resulting in rapid failure of product functionality. The existing solutions generally adopt the method of using hot melt adhesive to bond the reinforcing layer. Although this method controls the compression thickness loss rate within 25%, it causes the air permeability of the fabric to drop sharply from the original 3,500 liters per square meter per second to 1,200 liters per square meter per second, unable to meet the air permeability requirements of high-intensity sports scenarios.

[0004] Secondly, the problem of moisture conduction blockage is prominent. When the human body sweats during strenuous exercise, sweat accumulates between the surface hydrophobic polyester material and the bottom hydrophilic cotton fiber, forming condensate retention in the intermediate layer. Test data shows that after 30 minutes of use in an environment of 38 degrees Celsius and 90% relative humidity, the moisture content in the intermediate layer is as high as 29%, becoming a breeding ground for bacteria. The existing improvement technology improves the moisture permeability by opening micropores with a diameter of 0.8 millimeters on the surface. Although this solution increases the moisture permeability to 9,500 grams per square meter per day, the longitudinal and transverse breaking strengths of the fabric at the micropores decrease by more than 35%, greatly shortening the service life of the product.

[0005] Finally, the separation of the interlayer structure is a long-standing unsolved problem. In traditional double needle bed warp knitted fabrics, due to the proportion of interlayer connecting yarns being less than 6%, after 50 standard washing procedures, the interlayer peeling strength decays from the initial value of 22 Newtons per five centimeters to 9 Newtons per five centimeters. Although the latest bonding technology uses the melt spraying method to deposit a polyamide bonding layer between the layers, making the peeling strength maintained at 18 Newtons per five centimeters, it causes the bending stiffness of the fabric to increase to 120 millinewton centimeters, losing the flexible fit required by ergonomics.

[0006] The core contradiction revealed by the prior art lies in that the means of enhancing structural stability necessarily sacrifice air permeability and moisture permeability, and the measures to improve moisture conduction necessarily weaken mechanical strength. The split manufacturing process cannot break through these mutually restrictive performance bottlenecks. Therefore, it is necessary to design a sandwich structure fabric and its knitting method. Summary of the Invention

[0007] In order to overcome the defects in the prior art, the present invention provides a sandwich structure fabric and its knitting method.

[0008] In order to achieve the above object, the present invention provides the following technical solutions: A sandwich structure fabric includes a surface functional layer, an intermediate support layer, and a bottom contact layer that are sequentially distributed from top to bottom. The surface functional layer, the intermediate support layer, and the bottom contact layer are connected into one body through 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 the side length of a single cell is 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 connect the surface functional layer, the intermediate support layer, and the bottom contact layer simultaneously in an intermittent threading manner.

[0009] 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.

[0010] Preferably, the elastic multifilament yarns of the connecting yarn system penetrate from the surface functional layer, extend to the geometric center point of the basic hexagonal unit and bend 110° - 120°, and then penetrate to the bottom contact layer to form a spatial V-shaped anchoring structure.

[0011] Preferably, the distance between the geometric center points of the basic hexagonal units is 3.2 - 3.8 mm, and the deviation of the coincidence degree between the vertex of the spatial V-shaped anchoring structure and the geometric center point is ≤0.1 mm.

[0012] Preferably, the extending path of the connecting yarn system in the intermediate support layer is: penetrate from the side wall vertex of the basic hexagonal unit into the interior of the basic hexagonal unit, extend along the diagonal of the basic hexagonal unit to the geometric center point, and after bending at the geometric center point, extend along the diagonal of the adjacent basic hexagonal unit to the side wall vertex and penetrate out.

[0013] Preferably, the material of the surface functional layer is made of ultraviolet-shielding modified polyester filament, and its preparation method includes the following steps: treating TiO2 with a particle size of 25-40 nm and KH550 silane coupling agent at a mass ratio of 1:(0.8-1.2) at 75-85 °C for 40-50 min to obtain modified TiO2, and then melting and blending the modified TiO2 with PET at a ratio of 100:(1-1.5), spinning at 270-280 °C and 12-15 MPa, and then drawing at 3200-3500 m / min to obtain ultraviolet-shielding modified polyester filament.

[0014] Preferably, the material of 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 / 10 min, and the sheath layer material of the core-sheath composite fiber is PEG-PET copolyester.

[0015] Preferably, the preparation method of PEG-PET copolyester is: mixing polyethylene glycol with a molecular weight of 3000-3500, purified terephthalic acid, and ethylene glycol at a molar ratio of 1:(1.2-1.6):(0.4-0.6); adding 0.03-0.05 wt% of catalyst ethylene glycol antimonide, and the esterification temperature is 240-245 °C; in the polycondensation stage, the temperature is raised to 250-255 °C, the vacuum degree is less than 50 Pa, the reaction time is 120-150 min, and pelletizing is carried out to obtain PEG-PET copolyester.

[0016] Preferably, the elastic multifilament yarn is composed of spandex core yarn and polyether ester covering yarn, the fineness of the spandex core yarn is 20-30 D, the fineness of the polyether ester covering yarn is 40-60 D, the covering twist is 950-1100 twists / meter, and the proportion of the spandex core yarn in the elastic multifilament yarn is 35%-40%.

[0017] The present invention also provides a knitting method for a sandwich structure fabric, which is knitted by a double-sided circular weft knitting machine equipped with a surface needle system, a connecting needle system, and a bottom needle system, including the following steps: a. Knitting the surface functional layer: The surface needle system hooks the ultraviolet-shielding modified polyester filament to form a plain weft knitted coil layer on the needle cylinder, the loop density is 48-52 loops per inch, and the yarn feeding tension is 4.8-5.2 cN, which is the surface functional layer; b. Constructing the middle support layer: The surface needle system and the bottom needle system cooperate 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 1.5-1.8 mm, and the geometric center point distance of the basic hexagonal unit is 3.2-3.8 mm, which is the middle support layer; c. Knitting the 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.

[0018] Compared with the prior art, the advantages and beneficial effects of the present invention are: 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.

[0019] 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.

[0020] 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.

[0021] 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

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0023] In this application, the sources of various raw materials are briefly described as follows: Nano-titanium dioxide (TiO2) is of the VK-T30H model from Jiangsu Tianxing New Materials Co., Ltd.; KH550 silane coupling agent is of the ND-550 type KH550 from Hubei Xinlantian New Materials Co., Ltd.; PET uses PET chips of the YSC-800 specification from Zhejiang Rongsheng Petrochemical Co., Ltd.; polypropylene is of the EP548R model from Sinopec Maoming Company, with a melt index meeting 35-40 g / 10 min; polyethylene glycol is purchased as the PEG-3350 product from Jiangsu Dena Chemical Co., Ltd., with the molecular weight controlled at 3000-3500; purified terephthalic acid is of the PTA-FB-08 grade from Hengli Petrochemical; ethylene glycol is of the MEG-FG01 high-purity specification from Sinopec Shanghai Petrochemical Company; the catalyst uses XY-03 type ethylene glycol antimony from Hunan Xinyuan New Materials, with the antimony content not less than 55.8%; the spandex core yarn is of the Creora® CT-30D product from Hyosung Spandex Jiaxing Co., Ltd., with a fineness of 20-30 D; the polyether ester covered yarn is selected from the PBT-403 specification of Yantai Tayho Advanced Materials Co., Ltd., with a fineness range of 40-60 D.

[0024] A sandwich-structured fabric includes a surface functional layer, an intermediate support layer, and a bottom contact layer that are sequentially distributed from top to bottom. The surface functional layer, the intermediate support layer, and the bottom contact layer are connected into one body through 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 complex filament yarns that connect the surface functional layer, the intermediate support layer, and the bottom contact layer in an intermittent threading and sleeving manner.

[0025] The elastic complex filament yarns of the connecting yarn system penetrate from the surface functional layer, extend to the geometric center point of the basic hexagonal unit, bend 110°-120°, and then penetrate to the bottom contact layer to form a spatial V-shaped anchoring structure.

[0026] The distance between the geometric center points of the basic hexagonal units is 3.2-3.8 mm, and the deviation of the coincidence degree between the vertex of the spatial V-shaped anchoring structure and the geometric center point is ≤0.1 mm.

[0027] The extension path of the connecting yarn system within the intermediate support layer is as follows: It penetrates into the interior of the basic hexagonal unit from the vertex of the side wall 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 exits.

[0028] 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 - 40 nm and KH550 silane coupling agent are treated at a mass ratio of 1:(0.8 - 1.2) at 75 - 85 °C for 40 - 50 min to obtain modified TiO2. Then, the modified TiO2 and PET are melt-blended at a ratio of 100:(1 - 1.5), spun at 270 - 280 °C and 12 - 15 MPa, and then drawn at 3200 - 3500 m / min to obtain ultraviolet-shielding modified polyester filament.

[0029] The material of the bottom contact layer is core-sheath composite fiber. The core layer material of the core-sheath composite fiber is polypropylene with a melt index of 35 - 40 g / 10 min, and the sheath layer material of the core-sheath composite fiber is PEG-PET copolyester.

[0030] The preparation method of PEG-PET copolyester is as follows: Polyethylene glycol with a molecular weight of 3000 - 3500, purified terephthalic acid, and ethylene glycol are mixed at a molar ratio of 1:(1.2 - 1.6):(0.4 - 0.6); 0.03 - 0.05 wt% of catalyst ethylene glycol antimonide is added, and the esterification temperature is 240 - 245 °C; in the polycondensation stage, the temperature is raised to 250 - 255 °C, the vacuum degree is less than 50 Pa, and the reaction time is 120 - 150 min, and then pelletized to obtain PEG-PET copolyester.

[0031] The elastic complex yarn is composed of spandex core yarn and polyether ester covering yarn. The fineness of the spandex core yarn is 20 - 30 D, the fineness of the polyether ester covering yarn is 40 - 60 D, the covering twist is 950 - 1100 turns / meter, and the mass ratio of the spandex core yarn in the elastic complex yarn is 35% - 40%.

[0032] A knitting method for a sandwich structure fabric is carried out on a double-sided circular weft knitting machine equipped with a surface needle system, a connecting needle system, and a bottom needle system, including the following steps: a. Knitting of the surface functional layer: The surface needle system hooks the ultraviolet-shielding modified polyester filament to form a plain weft knitting coil layer on the needle cylinder, with a loop density of 48 - 52 loops per 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 hand needle system and the bottom needle system cooperate to form a periodic hexagonal honeycomb structure layer, which is composed of periodically arranged basic hexagonal units. The inner side length of the basic hexagonal unit is 1.5 - 1.8 mm, and the distance between the geometric center points of the basic hexagonal units is 3.2 - 3.8 mm, which is the intermediate support layer; c. Weaving the bottom contact layer: The bottom needle system hooks the core - sheath composite fiber to form a plain weft - knitted coil layer on the needle cylinder. The loop density is 58 - 62 loops per inch, and the yarn feeding tension is 5.0 - 5.5 cN, which is the bottom contact layer; d. Forming the spatial V - shaped anchoring structure: The connecting needle system performs the yarn threading action: entering the needle from the surface functional layer coil, positioning the puncture point at the vertex of the side wall of the basic hexagonal unit of the intermediate support layer, extending along the diagonal of the basic hexagonal unit to the geometric center point, bending 110° - 120° (forming a spatial V - shaped turn) at the geometric center point, then extending along the diagonal of the adjacent basic hexagonal unit to the vertex of the side wall and piercing out, and then connecting the coils of the bottom contact layer to form a spatial V - shaped anchoring structure. The obtained product is the sandwich - structured fabric.

[0033] The advantages of this application are concentrated in the synergistic effect of triple technological innovations: First, 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 intermediate 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 spatially precisely positioned through the V - shaped anchoring connection system. In this system, the elastic multifilament yarn bends 11,0 - 120 degrees at the geometric center point, and the positioning deviation between the vertex and the center point is strictly controlled within the range of 0.1 mm. Second, the integration of the manufacturing process. Using the hand needle system, connecting needle system, and bottom needle system of the double - sided circular weft knitting machine to operate synchronously. In the surface layer knitting, the functional layer is formed with a loop density of 48 - 52 loops per inch and a yarn feeding tension of 4.8 - 5.2 cN. In the construction of the support layer, the distance between the geometric center points of the hexagonal units is controlled to be 3.2 - 3.8 mm. In the bottom layer knitting, the contact layer is completed with a loop density of 58 - 62 loops per inch and a yarn feeding tension of 5.0 - 5.5 cN. Third, the in - situ property of the material function. The surface functional layer realizes ultraviolet protection through the treatment and modification of nano - titanium dioxide with a particle size of 25 - 40 nm and silane coupling agent at 75 - 85 °C and then melt - spinning with PET. The core - sheath structure of the bottom layer is composed of a polypropylene core layer with a melt index of 35 - 40 g per 10 minutes and a PEG - PET copolyester skin layer. The connecting yarn system is formed by compounding a 20 - 30 - denier spandex core yarn and a 40 - 60 - denier polyether - ester covering yarn with a twist of 950 - 1100 turns per meter to form an elastic support.

[0034] The technical solutions of the present invention are further illustrated by the following examples and comparative examples, but the protection scope of the present invention is not limited thereto.

[0035] Example 1: In this example, the fabric parameters are as follows: The surface functional layer uses a plain weft knitted coil layer with a thickness of 0.18 mm. When preparing the ultraviolet-shielding modified polyester filament, the TiO2 particle size is 25 nm, the mass ratio of KH550 silane coupling agent to TiO2 is 0.8:1, the mixing ratio of PET to modified TiO2 during melting is 100:1, the spinning temperature is 280 °C / 15 MPa, and the drawing speed is 3500 m / min. The side length of the hexagonal unit cell in the middle support layer is 1.8 mm, and the distance between the geometric center points is 3.8 mm; the thickness of the bottom contact layer is 0.18 mm. The melt index of polypropylene in the core-sheath composite fiber is 40 g / 10 min. When preparing the PEG-PET copolyester, the molecular weight of polyethylene glycol is 3500, the molar ratio is 1:1.6:0.6, and the polycondensation temperature is 255 °C / vacuum degree 50 Pa. The fineness of the spandex core yarn of the elastic multifilament yarn is 30 D, the fineness of the polyether ester covering yarn is 60 D, the twist is 1100 twists / meter, and the proportion of the spandex core yarn is 40%. During knitting, the loop density of the surface layer is 52 loops / inch, the yarn feeding tension is 5.2 cN, the loop density of the bottom layer is 62 loops / inch, and the yarn feeding tension is 5.5 cN; the piercing point of the connecting needle is positioned at the vertex of the hexagonal side wall, and the bending angle is 120°.

[0036] Example 2: In this example, the same parts as in Example 1 will not be described again, and the differences are as follows: The thickness of the surface functional layer is 0.22 mm, the particle size of the ultraviolet-shielding modified TiO2 is 40 nm, the proportion of the KH550 silane coupling agent is 1.2:1, the mixing ratio is 100:1.5, the spinning temperature is 270 °C / 12 MPa, and the drawing speed is 3200 m / min. The side length of the hexagon in the middle layer is 1.5 mm, and the distance between the center points is 3.2 mm; the thickness of the bottom contact layer is 0.15 mm, the melt index of polypropylene is 35 g / 10 min, the PEG-PET is prepared with a polyethylene glycol molecular weight of 3000, the molar ratio is 1:1.2:0.4, and the polycondensation temperature is 250 °C. The fineness of the spandex core yarn of the elastic multifilament yarn is 25 D, the fineness of the polyether ester covering yarn is 50 D, the twist is 1050 twists / meter, and the proportion of the spandex core yarn is 35%. Knitting parameters: The loop density of the surface is 50 loops / inch, the yarn feeding tension is 4.8 cN, the density of the bottom layer is 58 loops / inch, and the yarn feeding tension is 5.3 cN; the bending angle is 115°.

[0037] Example 3: In this example, the same parts as in Example 1 will not be described again, and the differences are as follows: The surface layer thickness is 0.20 mm, the TiO2 particle size is 32 nm, the ratio of KH550 silane coupling agent is 1:1, the melting and mixing ratio is 100:1.3, the spinning temperature is 275 °C / 13 MPa, and the drawing speed is 3350 m / min. The side length of the hexagon in the middle layer is 1.6 mm, and the center point spacing is 3.5 mm; the thickness of the bottom contact layer is 0.16 mm, the melt index of polypropylene is 38 g / 10 min, and the molar ratio of PEG-PET is 1:1.4:0.5. The fineness of the spandex core yarn of the elastic multifilament yarn is 20 D, the fineness of the polyether ester covering yarn is 40 D, the twist is 950 twists / m, and the proportion of the spandex core yarn is 38%. Knitting parameters: the surface loop density is 48 loops / inch, the yarn feeding tension is 5.0 cN, the bottom layer is 60 loops / inch, and the yarn feeding tension is 5.0 cN; the bending angle is 110°.

[0038] Comparative Example 1: In this comparative example, the same parts as in Example 1 will not be described in detail, and the differences are as follows: The middle support layer uses a traditional polyurethane foam layer (thickness 1.2 mm, density 0.25 g / cm 3 ), and the connection method is hot melt adhesive bonding (the thickness of the polyamide bonding layer is 0.1 mm).

[0039] Comparative Example 2: In this comparative example, the same parts as in Example 2 will not be described in detail, and the differences are as follows: The surface functional layer is changed to unmodified polyester filaments, and the hexagonal structure of the middle support layer is changed to a rectangular grid.

[0040] Comparative Example 3: In this comparative example, the same parts as in Example 3 will not be described in detail, and the differences are as follows: The honeycomb structure of the middle support layer is cancelled and changed to a double needle bed warp knitted spacer fabric (the proportion of connecting yarn is 6%).

[0041] Comparative Example 4: In this comparative example, the same parts as in Example 1 will not be described in detail, and the differences are as follows: The core-sheath composite fiber is removed from the bottom contact layer and changed to plain knitting with pure cotton fiber.

[0042] Comparative Example 5: The knitting process of Example 2 is adopted, but the bending angle of the connecting yarn is changed to 90°, and the deviation of the vertex from the center point of the hexagon is 0.3 mm.

[0043] Performance test results and analysis: The fabrics obtained according to the parameters of the examples and comparative examples are tested according to standards such as GB / T 24218, and the test results are shown in Table 1 specifically.

[0044] Table 1 Analysis and test results

[0045] The thickness loss rates of Examples 1-3 are all lower than 20%, which is significantly better than that of the comparative example. This benefits from the uniform dispersion of pressure by the hexagonal honeycomb structure and the spatial V-shaped anchoring effect of the elastic multifilament connecting yarn. In Comparative Example 1, due to the use of a foam layer and hot melt adhesive, permanent deformation occurs under pressure, demonstrating the compression resilience of this application.

[0046] The moisture permeability of Examples 1-3 exceeds 9500 g / m 2 ·d, which is 60% higher than that of Comparative Example 4. This verifies the hydrophilic / hydrophobic synergistic effect of the core-shell fiber: the cortical PEG-PET quickly absorbs sweat, and the intermediate honeycomb structure forms a continuous moisture conduction channel. In Comparative Example 2, due to the unmodified surface layer, sweat accumulates on the surface layer.

[0047] Structural stability: The interlayer peel strength of the examples reaches 23.5-24.7 N / 5 cm and still remains at 22.1-23.8 N / 5 cm after 50 washes. In Comparative Example 3, due to the insufficient proportion of the connecting yarn in the traditional warp knitting structure, the strength decays to 8.9 N / 5 cm. The design with the deviation of the V-shaped anchoring vertex from the center of the hexagon ≤ 0.1 mm is the key, compared with the 0.3 mm deviation of Comparative Example 5.

[0048] Flexibility balance: The bending stiffness of the examples ≤ 81.2 mN·cm, which is 34% lower than that of Comparative Example 1. This proves that the spatial V-shaped anchoring does not increase rigidity while enhancing the bonding, while the hot melt adhesive in Comparative Example 1 or the angular deviation in Comparative Example 5 will cause an increase in stiffness.

[0049] The above embodiments verify that the technical solution of the present invention successfully solves the three major defects in the background technology and achieves a performance breakthrough through the collaborative innovation of structure-material-process.

[0050] The above is the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle described in the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A sandwich-structured fabric, characterized in that, The invention comprises a surface functional layer, an intermediate support layer and a bottom contact layer, which are distributed in sequence 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 is composed of elastic multifilament yarns that are connected to the surface functional layer, the intermediate support layer and the bottom contact layer at the same time in an intermittent sleeve manner.

2. The sandwich structure fabric according to claim 1, wherein, 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.

3. The sandwich-structured fabric according to claim 2, wherein 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.

4. The sandwich structure fabric according to claim 3, 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.

5. The sandwich structure fabric according to claim 3, characterized in that, 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.

6. The sandwich structure fabric according to claim 1, wherein, 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.

7. The sandwich-structured fabric according to claim 1, wherein 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.

8. A sandwich-structured fabric according to claim 7, 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.

9. The sandwich-structured 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.

10. A knitting method for a sandwich-structured fabric, which is used to produce a sandwich-structured fabric as described in any one of claims 1-9, and is knitted by a double-sided circular weft knitting machine equipped with a face needle system, a connecting needle system, and a bottom needle system. It is 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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