Light and high-strength foaming fabric and preparation method thereof

Abstract

The invention provides a high-strength, light and supercritical foaming fabric and a preparation method thereof, complete fibers used by the fabric comprise core layer fibers and a skin layer material, the outer side of the core layer fibers is uniformly coated with the skin layer material, and the skin layer material can be foamed; the core layer fiber is at least one of aramid fiber, polyarylate fiber, polyimide fiber, ultra-high molecular weight polyethylene fiber, polyester fiber and polyamide fiber; and the skin layer is made of thermoplastic elastomer resin. The preparation method comprises the following steps: uniformly coating the outer side of the core layer fiber with the skin layer material, and then carrying out supercritical foaming on the skin layer material. According to the invention, the contradictory technical requirements of the fabric for shoes on strength, light weight, comfort and the like are solved in a simple mode; the body strength of the fiber for the shoes can be kept, and the characteristics of light weight and air permeability of the foaming fabric are also achieved; the difficulty of direct foaming of the fabric / fiber for shoes is reduced, and the vamp fabric and the shoe article which are uniform in foaming, breathable, light in weight, high in strength and soft can be obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of foam materials, and in particular relates to a light-weight, high-strength foam fabric and a preparation method thereof. Background Art

[0002] With the popularization of national sports, running has gradually become popular, and more and more people are keen on middle and long-distance running. The demand for running shoes, the most important equipment for running, is also increasing day by day. At the same time, higher requirements are put forward for running shoes, especially the fabrics of running shoes, such as light weight, breathability, foot protection, and durability. People continue to develop lighter running shoe fabrics. However, there is a certain contradiction between lightweight fabrics and foot protection and durability, because lightweight often means compromise in physical properties. How to design lightweight fabrics with good support and durability is a topic that needs urgent attention.

[0003] Supercritical foaming is a method for preparing low-density polymers. In recent years, it has been widely used in the field of sports shoe midsoles. However, there are no reports or patents on its application in the field of upper fabrics. The fundamental reason is that the diameter of the monofilament or multifilament of the upper fiber is very thin, generally tens to tens of microns, and the thickest does not exceed 1mm, which makes it difficult to perform supercritical foaming; secondly, even if foaming is successful through various means, the modulus of the material is inversely proportional to the foaming ratio, so the strength decreases as the weight is reduced, which is not worth the loss. Wang et al. studied the relationship between the elastic modulus and the foaming ratio of the material, and pointed out that the modulus decreases exponentially with the increase of the foaming ratio (the decrease of the density). In other words, the loss of modulus caused by foaming is much higher than the proportion of weight reduction. In this way, the method of foaming too fine upper fibers to achieve weight reduction is likely to be more costly than the gain.

[0004] Patent application CN113085220A in the prior art discloses a micro-foamed product of a continuous fiber reinforced thermoplastic resin, which is essentially a prepreg whose fibers have been widened and have a non-circular cross-section and cannot be applied to civilian fabrics; its process is prepreg tape-prepressing to prepare prepreg-molding-foaming, and the foaming process occurs after molding. The product is a hard part and is not suitable for civilian fabrics with high requirements for softness.

[0005] Chinese patent CN116770454B discloses a method for preparing foamed fibers. The foamed fibers have uniform internal pore structure and good tensile properties. However, the fiber does not meet the requirement of high strength and has low application value in shoe uppers. Summary of the invention

[0006] In view of the contradiction between lightweight upper fabrics and foot protection and wear resistance in the prior art, and the problem that lightweight fabrics are difficult to have good support and durability at the same time, the present invention provides a high-strength, lightweight, supercritical foamed fabric and a preparation method thereof.

[0007] The technical solution of the present invention is as follows: A high-strength, lightweight, supercritical foamed fabric. The complete fibers used in the fabric include core layer fibers and cortical materials. The cortical materials are uniformly coated on the outer side of the core layer fibers, and the cortical materials can be foamed; the core layer fibers are at least one of aramid fibers, polyarylate fibers, polyimide fibers, ultra-high molecular weight polyethylene fibers, polyester fibers, and polyamide fibers; the cortical materials are thermoplastic elastomer resins.

[0008] Further, the thickness of the core layer fibers is 10D - 1000D.

[0009] Further, the components of the cortical materials are: 95 - 100 parts of thermoplastic elastomer, 1 - 5 parts of nucleating agent, 0 - 2 parts of antioxidant, and other additives; the thermoplastic elastomer is at least one of thermoplastic polyurethane elastomer, thermoplastic polyester elastomer, and thermoplastic nylon elastomer.

[0010] Further, the melting point of the thermoplastic elastomer is 100 - 240 °C, and the hardness is 80A - 64D.

[0011] Preferably, the nucleating agent includes at least one of calcium carbonate, talcum powder, montmorillonite, nano-silica, polymer powder, carbon black, long-chain saturated carboxylate sodium salt, and long-chain saturated carboxylate calcium salt; the particle size of the nucleating agent is 0.05 - 3 μm.

[0012] A preparation method of a high-strength, lightweight, supercritical foamed fabric includes the following steps:

[0013] S1. After selecting the components of the above cortical materials, all components are dried, and then the cortical materials are coated on continuous core layer fibers by a screw extruder and wound up.

[0014] S2. The finished fibers obtained in S1 are woven into a mesh fabric.

[0015] S3. The mesh fabric obtained in S2 is heat-set.

[0016] S4. The heat-set mesh fabric is cut into the required shape, placed in an autoclave, supercritical fluid is introduced, saturated at a temperature of 120 - 200 °C and a pressure of 7 - 25 MPa, and then the pressure is quickly released to foam the thermoplastic elastomer in the cortex; the foamed fabric is obtained.

[0017] Further, the method of coating the skin material on the continuous core layer fibers in step S1 includes: directly blending all skin components with a twin-screw extruder and then directly coating them on the continuous core layer fibers, and then winding; or first blending all skin components with a twin-screw extruder, granulating them, and then coating the granulated particles on the continuous core layer fibers with a single-screw extruder, and then winding.

[0018] Further, the winding speed in step S1 is 10 - 200 m / min.

[0019] Further, the weaving method in step S2 can be any one of shuttle weaving, warp knitting, weft knitting, fly knitting, fly line, and 3D printing.

[0020] Further, the heat setting temperature in step S3 is 120 - 200 °C.

[0021] The advantages of the present invention are as follows: It solves the mutually contradictory technical requirements such as strength, light weight, and comfort of shoe fabrics in a simple way; it can not only retain the original strength of shoe fibers but also has the characteristics of light weight and breathability of foamed fabrics; the foaming process is simple, environmentally friendly, and can be continuously mass-produced on an industrial scale. It reduces the difficulty of directly foaming shoe fabrics / fibers and can obtain a foamed, uniform, breathable, light weight, high-strength, and soft upper fabric and footwear products. Description of the Drawings

[0022] Figure 1 It is a diagram of the foamed fabric sample in Example 3;

[0023] Figure 2 It is a diagram of the foamed fabric and the whole shoe sample in Example 3. Detailed Embodiments

[0024] 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 of them. 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.

[0025] The present invention aims to provide a light-weight and high-strength foamed fabric, which is more suitable for upper fabrics. The obtained fabric has the characteristics of light weight, uniform fiber thickness, porous structure, uniform cell structure, and high strength. At the same time, the method for preparing the foamed fabric provided by the present invention has low cost, is environmentally friendly, and can be continuously mass-produced on an industrial scale.

[0026] The present invention abandons the concept of directly foaming with fibers, but instead uses a continuous high-strength and high-temperature-resistant fiber as the core layer fiber, and coats a skin layer material of thermoplastic elastomer resin on the outside thereof with an extruder. Finally, a fiber with a skin-core structure is obtained. This fiber is woven into a mesh fabric as a mono yarn, and then the mesh fabric is supercritically foamed.

[0027] The core layer fiber is a filament fiber, which can be at least one filament of aramid fiber, polyarylate fiber, polyimide fiber, ultra-high molecular weight polyethylene fiber, polyester fiber, polyamide fiber. Preferably, it is aramid fiber and polyarylate fiber. The thickness of the fiber is 10D - 1000D. Preferably, the thickness of the fiber is 50D, 100D, 150D, 200D.

[0028] The skin layer material is mainly composed of at least one of thermoplastic polyurethane (TPU) elastomer, thermoplastic polyester elastomer, and thermoplastic nylon elastomer.

[0029] Preferably, the components of the skin layer material are: 95 - 100 parts of thermoplastic elastomer, 1 - 5 parts of nucleating agent, 0 - 2 parts of antioxidant and other additives. Any well-known antioxidants and other additives in the art can be used, and their functions and effects are relatively clear. The present invention does not have special limitations on this.

[0030] Among them, the melting point of the thermoplastic elastomer is 100 - 240 °C, and the hardness is 80A - 64D. Preferably, the nucleating agent includes at least one of calcium carbonate, talcum powder, montmorillonite, nano-silica, polymer powder, carbon black, long-chain saturated carboxylate sodium salt, and long-chain saturated carboxylate calcium salt. The particle size of the nucleating agent is 0.05 - 3 μm.

[0031] After coating the skin layer material on the surface of the core layer fiber with an extruder, the overall diameter reaches 0.5 - 2 mm; preferably, the diameter is 0.8 - 1.2 mm. Before foaming, the mesh fabric woven from the coated fiber can be heat-set first to melt and bond the skin layer parts in the warp and weft directions at the joints, making the structure of the mesh fabric more stable.

[0032] Specifically, the preparation method of the lightweight and high-strength foamed fabric of the present invention includes the following steps:

[0033] S1. After selecting the components of the above skin layer material, all components are dried, and then the skin layer material is coated on the continuous core layer fiber with a screw extruder and wound up;

[0034] S2. Weave the finished fiber obtained in S1 into a mesh fabric;

[0035] S3. Heat-set the mesh fabric obtained in S2;

[0036] S4. Cut the heat-set fabric into the required shape, place it in an autoclave, introduce supercritical fluid, saturate it at a temperature of 120 - 200 °C and a pressure of 7 - 25 MPa, and then quickly release the pressure to foam the thermoplastic elastomer in the skin layer; obtain the foamed fabric.

[0037] In step S1, there are two ways to coat the skin layer material on the continuous core layer fibers with a screw extruder. One is to directly blend all the skin layer components with a twin-screw extruder and then directly coat them on the continuous core layer fibers and wind them up; the other is to first blend all the skin layer components with a twin-screw extruder and then granulate them, and then coat the granulated particles on the continuous core layer fibers with a single-screw extruder and wind them up.

[0038] Each of the two coating methods has its own advantages. The first one saves time, and the second one coats the skin layer material more evenly.

[0039] In step S1, the winding speed is 10 - 200 m / min.

[0040] In step S2, the weaving method can be any one of weaving, warp knitting, weft knitting, fly knitting, fly line, and 3D printing.

[0041] In step S3, the heat-setting temperature is 120 - 200 °C.

[0042] The following further illustrates the specific performance of the present invention through several specific embodiments.

[0043] Example 1

[0044] Core layer fiber: 200D aramid fiber

[0045] Skin layer material components:

[0046] Thermoplastic elastomer: TPU elastomer, 85A, 96.5 parts;

[0047] Nucleating agent: 2 parts of talcum powder;

[0048] Antioxidant: 0.5 part of hindered phenol 1010, 1 part of antioxidant 168.

[0049] Corresponding preparation method of lightweight and high-strength foamed fabric:

[0050] S1. After selecting the components of the above skin layer material, dry all the components, then add them into a twin-screw extruder to blend all the skin layer components and directly coat them on the continuous core layer fibers and wind them up; the diameter of the obtained finished fiber is 1.0 mm;

[0051] S2. Weave the finished fiber obtained in S1 into a fabric by weaving; the warp and weft density of the fabric is 40 * 40 yarn counts, and the mesh size is 1.5 mm * 1.5 mm;

[0052] S3. Heat set the mesh fabric obtained in S2 at a heat setting temperature of 160 °C;

[0053] S4. Cut the heat-set mesh fabric into the required shape, place it in an autoclave for supercritical foaming, introduce CO2, saturate it at a temperature of 150 °C and a pressure of 15 MPa, and then quickly release the pressure to foam the skin material to obtain a foamed fabric sample.

[0054] After measurement, the diameter of the finished fiber in the foamed mesh fabric is 1.76 mm. The overall size of the mesh fabric remains unchanged, but the mesh size becomes 0.74 mm x 0.74 mm. It can be seen that the pores decrease after foaming. The warp and weft tensile strengths of the foamed mesh fabric are 430 N / 2.5 cm and 400 N / 2.5 cm respectively; the weight is 32 g. The tensile strength fully meets the use requirements of the shoe upper.

[0055] Example 2

[0056] Core layer fiber: 400D ultra-high molecular weight polyethylene fiber

[0057] Skin material components:

[0058] Thermoplastic elastomer: thermoplastic polyester elastomer, 80A, 95.5 parts;

[0059] Nucleating agent: 3 parts of talc powder;

[0060] Antioxidant: 0.5 part of hindered phenol 1010, 1 part of antioxidant 168.

[0061] Corresponding preparation method of lightweight and high-strength foamed fabric:

[0062] S1. After selecting the components of the above skin material, dry all the components, then add them to a twin-screw extruder to blend all the skin components and granulate them, and then use a single-screw extruder to coat the granulated particles on the continuous core layer fiber, and wind it up with water cooling; the diameter of the obtained finished fiber is 1.5 mm; since ultra-high molecular weight polyethylene fiber is not resistant to high temperature, it is necessary to ensure that the upper limit of the extruder temperature does not exceed 160 °C, the extrusion rate is not less than 40 m / min, and wind it up with water cooling.

[0063] S2. Weave the finished fiber obtained in S1 into a mesh fabric by shuttle weaving; the warp and weft densities of the mesh fabric are 29*29 yarn counts, and the mesh size is 2 mm * 2 mm;

[0064] S3. Heat set the mesh fabric obtained in S2 at a heat setting temperature of 130 °C;

[0065] S4. Cut the shaped mesh fabric into the required shape, place it in an autoclave for supercritical foaming, introduce CO2, saturate it at a temperature of 135°C and a pressure of 15 MPa, and then quickly release the pressure to foam the skin material, obtaining a foamed fabric sample.

[0066] After measurement, the diameter of the finished fibers in the foamed mesh fabric is 1.9 mm. The overall size of the mesh fabric remains unchanged, but the mesh size becomes 1.6 mm * 1.6 mm. It can be seen that the pore size decreases after foaming. The warp and weft tensile strengths of the foamed mesh fabric are 1000 N / 2.5 cm and 920 N / 2.5 cm respectively, and the weight is 38 g. Thanks to the relatively high strength of ultra-high molecular weight polyethylene, the tensile strength of this mesh fabric is very high, fully meeting the usage requirements of the shoe upper.

[0067] Example 3

[0068] Core layer fiber: 800D polyarylate fiber

[0069] Skin material components:

[0070] Thermoplastic elastomer: Thermoplastic nylon elastomer, 90A, 95.5 parts;

[0071] Nucleating agent: Talc powder 3 parts;

[0072] Antioxidant: Hindered phenol 1010 0.5 parts, antioxidant 168 1 part.

[0073] Corresponding preparation method of lightweight and high-strength foamed fabric:

[0074] S1. After selecting the components of the above skin material, dry all the components, then add them into a twin-screw extruder to blend all the skin components and granulate them. Then use a single-screw extruder to coat the granulated particles on the continuous core layer fibers, and wind them up with water cooling. The diameter of the obtained finished fiber is 1.0 mm;

[0075] S2. Weave the finished fibers obtained in S1 into a mesh fabric by fly-knitting; the mesh size is 3 mm * 3 mm;

[0076] S3. Thermally set the mesh fabric obtained in S2 at a temperature of 160°C;

[0077] S4. Cut the shaped mesh fabric into the required shape, place it in an autoclave for supercritical foaming, introduce CO2, saturate it at a temperature of 155°C and a pressure of 15 MPa, and then quickly release the pressure to foam the skin material, obtaining a foamed fabric sample. As Figure 1 shown.

[0078] After measurement, the diameter of the finished fiber in the foamed mesh fabric is 1.85 mm. The overall size of the mesh fabric remains unchanged, but the mesh size becomes 2.15 mm * 2.15 mm. After foaming, the pore size decreases. The warp and weft tensile strengths of the foamed mesh fabric are 1700 N / 2.5 cm and 1600 N / 2.5 cm respectively, and the weight is 90 g.

[0079] The polyarylate fiber has a relatively high body strength, but it is also heavier than other fibers. The tensile strength of this mesh fabric is very high, fully meeting the usage requirements of the shoe upper.

[0080] Example 4

[0081] Core layer fiber: 100D polyimide fiber

[0082] Skin layer material components:

[0083] Thermoplastic elastomer: Thermoplastic nylon elastomer, 40D, 95.5 parts;

[0084] Nucleating agent: 3 parts of talcum powder;

[0085] Antioxidant: 0.5 part of hindered phenol 1010, 1 part of antioxidant 168.

[0086] Corresponding preparation method of lightweight and high-strength foamed fabric:

[0087] S1. After selecting the components of the above skin layer material, all components are dried, then added to a twin-screw extruder to blend all skin layer components and granulate. Then, the granulated particles are coated on the continuous core layer fibers with a single-screw extruder, and water-cooled and wound up. The diameter of the obtained finished fiber is 0.8 mm;

[0088] S2. The finished fiber obtained in S1 is used to 3D print a three-dimensional slipper upper;

[0089] S3. The upper obtained in step S2 is put into an autoclave for supercritical foaming. CO2 is introduced and saturated at a temperature of 155 °C and a pressure of 15 MPa. Then, the pressure is quickly released to make the skin layer material foam, obtaining a foamed fabric sample. As Figure 2 shown.

[0090] After measurement, the diameter of the finished fiber in the foamed mesh fabric is 2.1 mm; the weight of the upper together with the whole slipper is 120 g.

[0091] Due to the 3D stereoscopic printing method that can construct a multi-level three-dimensional structure, the upper has more intersection points, combining the characteristics of better softness and stability. Therefore, the whole shoe can also be directly made by 3D printing combined with the foaming method of the present invention, meeting the usage scenarios such as household slippers, and obtaining more lightweight, comfortable, soft and strong shoe products.

[0092] Comparative Example 1

[0093] Core layer fiber: 200D aramid fiber

[0094] Skin layer material components:

[0095] Thermoplastic elastomer: thermoplastic polyester elastomer, 85A, 96.5 parts;

[0096] Nucleating agent: 2 parts of talcum powder;

[0097] Antioxidant: 0.5 part of hindered phenol 1010, 1 part of antioxidant 168.

[0098] Corresponding fabric preparation method:

[0099] S1. After selecting the components of the above skin layer material, all components are dried, and then added to a twin-screw extruder to blend all skin layer components, and then directly coated on continuous core layer fibers and wound up; the diameter of the obtained finished fiber is 1.0 mm;

[0100] S2. The finished fiber obtained in S1 is woven into a mesh fabric by shuttle weaving; the warp and weft densities of the mesh fabric are 57*57 yarn counts, and the mesh size is 0.74 mm * 0.74 mm;

[0101] S3. Heat set the mesh fabric obtained in S2, and the heat setting temperature is 160 °C;

[0102] This mesh fabric is not further foamed, and the mesh size is the same as that of Example 1; the warp and weft tensile strengths of the mesh fabric are 580 N / 2.5 cm and 530 N / 2.5 cm respectively; the weight is 60 g.

[0103] Compared with Example 1, in Comparative Example 1, the fiber consumption is more, and the weight increases by about 87.5%, but the strength only increases by 40% compared with Example 1. It shows that the foamed fabric of the present invention greatly retains the body strength of the fiber, and under the condition of ensuring that the strength fully meets the use, the fiber consumption is less, achieving a more effective weight reduction effect.

[0104] The above are only the preferred embodiments of the present invention, and do not constitute any form of limitation to the present invention. Although the present invention has been disclosed above with the preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art of this patent, without departing from the scope of the technical solution of the present invention, can make some changes or modifications using the technical content prompted above as equivalent embodiments of equivalent changes, but as long as it does not depart from the content of the technical solution of the present invention, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A high-strength, lightweight, supercritical foamed fabric, characterized in that: The complete fiber used in the fabric includes core fiber and skin material. The skin material is evenly coated on the outside of the core fiber, and the skin material can be foamed. The core fiber is at least one of aramid fiber, polyarylate fiber, polyimide fiber, ultra-high molecular weight polyethylene fiber, polyester fiber, and polyamide fiber. The skin material is thermoplastic elastomer resin.

2. The high-strength, lightweight, supercritical foamed fabric according to claim 1, characterized in that: The thickness of the core layer fiber is 10D-1000D.

3. The high-strength, lightweight, supercritical foamed fabric according to claim 1, characterized in that: The components of the skin material are: 95-100 parts of thermoplastic elastomer, 1-5 parts of nucleating agent, 0-2 parts of antioxidant and other additives; the thermoplastic elastomer is at least one of thermoplastic polyurethane elastomer, thermoplastic polyester elastomer and thermoplastic nylon elastomer.

4. The high-strength, lightweight, supercritical foamed fabric according to claim 3, characterized in that: The melting point of thermoplastic elastomer is 100-240°C and the hardness is 80A-64D.

5. The high-strength, lightweight, supercritical foamed fabric according to claim 3, characterized in that: The nucleating agent comprises at least one of calcium carbonate, talcum powder, montmorillonite, nano silicon dioxide, polymer powder, carbon black, long-chain saturated carboxylic acid sodium salt and long-chain saturated carboxylic acid calcium salt; the particle size of the nucleating agent is 0.05-3 μm.

6. A method for preparing a high-strength, lightweight, supercritical foamed fabric, characterized in that: The steps include: S1. After selecting the components of the skin material as described in any one of claims 3 to 4, all the components are dried, and then the skin material is coated on the continuous core fiber by a screw extruder, and then rolled up; S2, weaving the finished fibers obtained in S1 into a mesh; S3, heat setting the mesh obtained in S2; S4. Cut the heat-set mesh into required shapes, put it into an autoclave, introduce supercritical fluid, saturate it at a temperature of 120-200° C. and a pressure of 7-25 MPa, then quickly release the pressure to foam the thermoplastic elastomer in the skin layer; and obtain the foamed fabric.

7. The method for preparing the high-strength, light-weight, supercritical foamed fabric according to claim 6, characterized in that: In step S1, the method of using a screw extruder to coat the skin layer material on the continuous core layer fiber includes: directly using a twin-screw extruder to blend all the skin layer components, and then directly coating them on the continuous core layer fibers and winding them up; or first using a twin-screw extruder to blend all the skin layer components and then granulate them, and then using a single-screw extruder to coat the granulated particles on the continuous core layer fibers and winding them up.

8. The method for preparing the high-strength, light-weight, supercritical foamed fabric according to claim 6 or 7, characterized in that: The winding speed in step S1 is 10-200 m / min.

9. The method for preparing the high-strength, light-weight, supercritical foamed fabric according to claim 6, characterized in that: The weaving method in step S2 can be any one of weaving, warp knitting, weft knitting, flying weaving, flying line, and 3D printing.

10. The method for preparing the high-strength, light-weight, supercritical foamed fabric according to claim 6, characterized in that: The heat setting temperature in step S3 is 120-200°C.

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