A fiber composite material having a core-sheath structure and a method for producing the same

Abstract

This invention belongs to the field of fiber composite materials technology, specifically relating to a fiber composite material with a core-sheath structure and its preparation method. The fiber composite material includes a core layer and a sheath layer. The core layer contains PET with a melting point of 250℃-260℃ and an intrinsic viscosity of 0.68 dL / g-0.80 dL / g. The sheath layer contains COPET with a melting point of 230℃-240℃ and an intrinsic viscosity of 0.64 dL / g-0.68 dL / g. This fiber composite material, and the fiber mat obtained based on it, exhibits excellent tensile and tear strength, such as a thickness of 2mm-4mm and a basis weight of 800g / m². 2 -2000g / m 2 According to GB / T529-2008, the tensile strength of the fiber felt can reach 34.9 MPa and the tear strength can reach 299.8 N.

Description

Technical Field

[0001] This invention belongs to the field of fiber composite materials technology, specifically relating to a fiber composite material with a core-sheath structure and its preparation method. Background Technology

[0002] With the rapid development of industrial manufacturing, transportation, and building materials, increasingly higher demands are being placed on the mechanical properties, processing adaptability, and application stability of fiber composite materials. Due to their advantages such as lightweight, high strength, and corrosion resistance, fiber composite materials have widely replaced traditional materials such as metals and wood in the manufacture of structural components, protective materials, and filter materials. Among these, fiber felt, as a common molded product, directly determines the service life and safety reliability of the end product through its tensile strength and tear strength. In applications such as automotive interiors, building insulation, and industrial filtration, fiber felt often needs to maintain structural integrity under certain external forces to avoid failures such as breakage and tearing. Therefore, the development of high-performance fiber composite materials and fiber felt has become a key research focus in the industry. Currently, most fiber composite materials on the market are prepared using single-component fibers or simple blended fibers. Single-component fibers struggle to simultaneously achieve good processing flowability and finished product mechanical properties. For example, while pure PET fiber possesses certain strength, its high melting point necessitates higher temperatures during processing, easily leading to uneven fiber melting and affecting the structural consistency of the product. Conventional blended fibers, on the other hand, suffer from poor compatibility and insufficient interfacial bonding between different components, making them prone to component separation under stress. This results in fiber composite materials failing to meet the tensile and tear strength requirements of high-end applications. Furthermore, while some core-sheath structure fibers optimize performance through the combination of different components, the design of the melting point difference between the core and sheath layers in existing core-sheath structures is unreasonable. Either the melting points are too close, making it difficult to form a stable core-sheath structure during processing, or the melting point difference is too large, resulting in weak interfacial bonding. Simultaneously, the lack of precise matching of the intrinsic viscosity parameters of the components further limits the improvement of the mechanical properties of fiber composite materials.

[0003] Given the shortcomings of the existing technologies, there is an urgent need to develop a fiber composite material with excellent mechanical properties. Summary of the Invention

[0004] Based on this, the present invention, by rationally designing the melting point range and intrinsic viscosity range of the core layer PET and the sheath layer COPET, not only ensures the stable forming of the core-sheath structure during processing, but also enhances the interfacial bonding force between the core layer and the sheath layer, thereby significantly improving the tensile strength and tear strength of the fiber composite material and the corresponding fiber felt, so as to meet the urgent demand for high-performance fiber products in industrial production and expand the application scope of fiber composite materials in high-end fields.

[0005] To achieve the above objectives, the present invention can adopt the following technical solutions: The present invention provides a fiber composite material with a core-sheath structure, comprising a core layer and a sheath layer. The core layer comprises PET, which has a melting point of 250℃-260℃ and an intrinsic viscosity of 0.68dL / g-0.80dL / g. The sheath layer comprises COPET, which has a melting point of 230℃-240℃ and an intrinsic viscosity of 0.64dL / g-0.68dL / g.

[0006] Preferably, in the above-mentioned fiber composite material, PET is obtained by adding chain extenders to recycled PET, and the intrinsic viscosity of recycled PET is <0.68 dL / g; and / or COPET is obtained by copolymerizing polyethylene isophthalate and polyethylene terephthalate.

[0007] Preferably, in the above-mentioned fiber composite material, the mass of the sheath layer is 10%-30% of the total mass of the core layer and the sheath layer.

[0008] Preferably, in the above-mentioned fiber composite material, the mass of the sheath layer is 30% of the total mass of the core layer and the sheath layer.

[0009] Preferably, in the above-mentioned fiber composite material, the core layer further includes color masterbatch and / or PA material; and / or the sheath layer further includes one or more of water-blocking agent, flame retardant or EPR material.

[0010] Preferably, in the above-mentioned fiber composite material, the color masterbatch is PET containing 25%-35% graphite by mass; and / or the water barrier is selected from fluorinated acrylate copolymers and / or fluorine-free acrylate copolymers; and / or the flame retardant is selected from one or more combinations of alkyl phosphonic acid metal salts, phosphonic acid organic amine salts, or phosphonic acid; and / or the PA material is selected from one or more combinations of PA6, PA66, PA11, or PA12.

[0011] Preferably, in the above-mentioned fiber composite material, the mass of the color masterbatch is 1%-3% of the mass of PET; and / or the mass of the PA material is 1%-10% of the mass of PET; and / or the mass of the water barrier agent is 1%-10% of the mass of COPET; and / or the mass of the flame retardant is 1%-3% of the mass of COPET; and / or the mass of the EPR material is 5%-15% of the mass of COPET.

[0012] Another aspect of the present invention provides a method for preparing the above-mentioned fiber composite material, the method comprising: (1) feeding the molten sheath and core layer into a coaxial electrospinning machine for spinning to obtain a composite fiber with sheath covering the core layer, the spinning temperature being 270℃-300℃; (2) cooling and molding the composite fiber with sheath covering the core layer at a temperature of 120℃-140℃ to obtain the fiber composite material.

[0013] In another aspect, the present invention provides a fiber felt, which is prepared from the above-mentioned fiber composite material, wherein the thickness of the fiber felt is 2mm-4mm and the basis weight is 800g / m³. 2 -2000g / m 2 .

[0014] In another aspect, the present invention provides a method for preparing the above-mentioned fiber felt, the method comprising: (1) laying composite fibers into a web and spunbonding to obtain a base fabric; (2) laying the base fabric into a 45° cross web to obtain an overlapping base fabric; (3) performing at least one needle punching and entanglement on the overlapping base fabric to obtain a fiber felt semi-finished product; and (4) performing steam forming treatment on the fiber felt semi-finished product to obtain a fiber felt.

[0015] Preferably, in the above preparation method, (i) the pressure of the steam forming treatment is 14 Bar-17 Bar; and / or (ii) based on (i), the steam forming treatment time is 13 s-20 s; and (iii) the temperature of the steam forming treatment is 200℃-210℃.

[0016] The beneficial effects of this invention include: the fiber composite material with a core-sheath structure provided by this invention, and the fiber felt obtained based on this fiber composite material, have excellent tensile strength and tear strength, such as a thickness of 2mm-4mm and a basis weight of 800g / m². 2 -2000g / m 2 According to GB / T529-2008, the tensile strength of the fiber felt can reach 34.9 MPa and the tear strength can reach 299.8 N. Detailed Implementation

[0017] The embodiments described are provided to better illustrate the present invention, but are not intended to limit the scope of the invention to the embodiments described. Therefore, non-essential improvements and adjustments made to the embodiments by those skilled in the art based on the above description are still within the scope of protection of the present invention.

[0018] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. Singular expressions include plural expressions unless they have a distinct meaning in the context. As used herein, it should be understood that terms such as “comprising,” “having,” “including,” are intended to indicate the presence of features, numbers, operations, components, parts, elements, materials, or combinations thereof. The terminology of the invention is disclosed in the specification and is not intended to exclude the possibility that one or more other features, numbers, operations, components, parts, elements, materials, or combinations thereof may be present or added. As used herein, “ / ” may be interpreted as “and” or “or,” depending on the context.

[0019] In a first aspect, this embodiment provides a fiber composite material with a core-sheath structure, comprising a core layer and a sheath layer. The core layer contains PET, which has a melting point of 250°C-260°C and an intrinsic viscosity of 0.68 dL / g-0.80 dL / g. The sheath layer contains COPET, which has a melting point of 230°C-240°C and an intrinsic viscosity of 0.64 dL / g-0.68 dL / g.

[0020] It should be noted that by rationally designing the melting point range and intrinsic viscosity range of the core layer PET and the sheath layer COPET, this invention not only ensures the stable forming of the core-sheath structure during processing, but also enhances the interfacial bonding force between the core layer and the sheath layer. This significantly improves the tensile strength and tear strength of the fiber composite material and the corresponding fiber felt, thereby meeting the urgent demand for high-performance fiber products in industrial production and expanding the application scope of fiber composite materials in high-end fields. Among them, PET has a higher melting point than COPET, and PET has a higher intrinsic viscosity than COPET. The melting point of PET can be 250℃-260℃, such as 253℃, 255℃ or 257℃, etc., while the melting point of COPET can be 230℃-240℃, such as 233℃, 255℃ or 257℃, etc.; the intrinsic viscosity of PET can be 0.68dL / g-0.80dL / g, such as 0.70dL / g, 0.75dL / g or 0.78dL / g, etc., while the intrinsic viscosity of COPET can be 0.64dL / g-0.68dL / g, such as 0.65dL / g / 0.66dL / g or 0.67dL / g, etc.

[0021] In some specific examples, the PET in the above-mentioned fiber composite material is obtained by adding chain extenders to recycled PET, and the intrinsic viscosity of recycled PET is <0.68 dL / g; It should be noted that the PET (polyethylene terephthalate) used in this invention is known in the art and can be recycled PET. When the intrinsic viscosity of the recycled PET is <0.68 dL / g, a chain extender can be added to increase the intrinsic viscosity of the PET. The chain extender is known in the art, such as chain extender 4300 or chain extender 4368, etc., and its addition amount is 1%-7% (e.g., 2%, 3%, 4%, 5% or 6% of the PET mass). Furthermore, it should be noted that if the viscosity of the recycled PET is greater than 0.8, its performance remains essentially unchanged, and no further processing is required.

[0022] In some specific examples, in the above-mentioned fiber composite materials, COPET is obtained by copolymerization of polyethylene isophthalate and polyethylene terephthalate.

[0023] It should be noted that the COPET in this invention can be obtained by copolymerizing polyethylene isophthalate and polyethylene terephthalate. The mass ratio of polyethylene isophthalate to polyethylene terephthalate is 1-4:(6-9), such as 1:7, 2:7, 3:7. Adjusting the melting point of COPET by controlling the ratio of the two is a conventional method in the art.

[0024] In some specific examples, the mass of the sheath layer in the above-mentioned fiber composite material is 10%-30% of the total mass of the core layer and the sheath layer.

[0025] It should be noted that in this invention, if there is too little or too much COPET, the tensile strength, tear strength, and sound absorption coefficient will all decrease. Specifically, if too little sheath is added, the final felt will have poor formability and the tensile strength will drop sharply. Therefore, the mass of the sheath layer in this invention can be further preferably 10%-30% of the total mass of the core layer and the sheath layer, such as 15%, 20%, or 25%, that is, the mass ratio of the core layer to the sheath layer can be 9:1, 8:2, or 7:3, etc.

[0026] In some specific examples, the mass of the sheath layer in the aforementioned fiber composite material is 30% of the total mass of the core layer and the sheath layer.

[0027] It should be noted that the mass of the sheath layer in this invention can be further preferably 30% of the total mass of the core layer and the sheath layer, that is, the mass ratio of the sheath layer to the core layer is 7:3. The performance of the fiber composite material prepared under this ratio is better than that under other ratios.

[0028] In some specific examples, the core layer of the aforementioned fiber composite material also contains color masterbatch and / or PA (polyamide) material.

[0029] It should be noted that color masterbatch can be added to the core layer to enrich the color of fiber composite materials; in addition, PA material can be added to the core layer to improve the sound absorption performance of fiber composite materials and increase the sound absorption coefficient.

[0030] In some specific examples, the color masterbatch in the above-mentioned fiber composite material is PET containing 25%-35% graphite by mass.

[0031] It should be noted that the color masterbatch in this invention is used to increase the color of the fiber composite material. The color masterbatch in this invention can preferably be PET containing 25%-35% (e.g., 27%, 30% or 33% by mass) of graphite. This color masterbatch will not significantly affect the mechanical properties of the fiber composite material.

[0032] In some specific examples, in the above-mentioned fiber composite materials, the PA material is selected from one or more combinations of PA6, PA66, PA11 or PA12.

[0033] It should be noted that the PA material used in this invention is known in the art, including but not limited to one or more combinations of PA6, PA66, PA11 or PA12.

[0034] In some specific examples, in the above-mentioned fiber composite materials, the mass of the color masterbatch is 1%-3% of the mass of PET; and / or the mass of the PA material is 1%-10% of the mass of PET.

[0035] It should be noted that the mass of the color masterbatch (PET containing 25%-35% graphite by mass) added in this invention can be further preferably 1%-3% of the mass of PET, such as 1.3%, 1.5% or 1.7%; the mass of PA material can be further preferably 1%-10% of the mass of PET, such as 3%, 5% or 7%.

[0036] In some specific examples, the sheath of the aforementioned fiber composite material also contains one or more of a water-blocking agent, a flame retardant, or an EPR material.

[0037] It should be noted that because PET contains ester groups, it has a certain degree of hydrophilicity. In order to prevent the product from absorbing water, a water-blocking agent can be added to the sheath layer in this invention to prevent or reduce the product from absorbing water. In addition, a flame retardant can be added to the sheath layer to increase the flame retardant performance, and EPR material can be added to the sheath layer to increase the sound absorption coefficient.

[0038] In some specific examples, in the above-mentioned fiber composite materials, the water-blocking agent is selected from fluorinated acrylate copolymers and / or fluorine-free acrylate copolymers; and / or the flame retardant is selected from one or more combinations of alkyl phosphonic acid metal salts, phosphonic acid organic amine salts, or phosphonic acids.

[0039] In some specific examples, the core layer of the aforementioned fiber composite material also contains PA (polyamide) material, while the sheath layer also contains EPR material.

[0040] It should be noted that by adding PA (polyamide) material to the core layer and EPR material to the sheath layer, the PA (polyamide) material and EPR material can synergistically increase the sound absorption coefficient of the fiber composite material. In the 2500HZ frequency band, the sound absorption coefficient can reach 0.85.

[0041] In some specific examples, in the above-mentioned fiber composite materials, the mass of the water-blocking agent is 1%-10% of the mass of COPET; and / or the mass of the flame retardant is 1%-3% of the mass of COPET; and / or the mass of the EPR material is 5%-15% of the mass of COPET.

[0042] It should be noted that the mass of the water-blocking agent in this invention can be 1%-10% of the mass of COPET, such as 3%, 5% or 7%; the mass of the flame retardant can be 1%-3% of the mass of COPET, such as 1.5%, 2% or 2.5%; and the mass of the EPR material can be 5%-15% of the mass of COPET, such as 7%, 10% or 13%.

[0043] In a second aspect, the present invention provides a method for preparing the above-mentioned fiber composite material. The method includes: (1) feeding the molten sheath and core layer into a coaxial electrospinning machine for spinning to obtain a composite fiber with the sheath covering the core layer. The spinning temperature is 270℃-300℃; (2) cooling and molding the composite fiber with the sheath covering the core layer at a temperature of 120℃-140℃ to obtain the fiber composite material.

[0044] It should be noted that the sheath-core structure of fiber composites is the core to achieving functional synergy. Coaxial electrospinning technology can precisely control the uniformity of coating between the sheath and core layers, avoiding the interlayer separation problem that occurs in traditional composite processes. This method is suitable for preparing high-strength, multifunctional fiber composites and can be widely used in filter materials, biomedical scaffolds, smart textiles, and other fields, while also offering advantages such as simple processing and scalable production. Furthermore, the key process parameters of the coaxial electrospinning machine can be flexibly adjusted according to the viscosity and surface tension of the sheath and core materials to further optimize the coating effect and morphology of the composite fibers. The above parameter ranges are within the industry's standard range, ensuring the stability of the spinning process.

[0045] Thirdly, embodiments of the present invention provide a fiber felt, which is prepared from the above-mentioned fiber composite material, the fiber felt having a thickness of 2mm-4mm and a basis weight of 800g / m³. 2 -2000g / m 2 .

[0046] It should be noted that the fiber composite material in this invention has excellent mechanical and sound absorption properties, and can be used as a car's underbody protection plate / mudguard, which can meet the requirements of lightweighting of new energy vehicle parts.

[0047] Fourthly, the present invention provides a method for preparing the above-mentioned fiber felt, the method comprising: (1) laying composite fibers into a web and spunbonding to obtain a base fabric; (2) laying the base fabric into a 45° cross web to obtain an overlapping base fabric; (3) performing at least one needle punching and entanglement on the overlapping base fabric to obtain a fiber felt semi-finished product; (4) performing steam forming treatment on the fiber felt semi-finished product to obtain a fiber felt.

[0048] It should be noted that the 45° cross-laying in this invention is to solve the problem of difference in strength between the transverse and longitudinal directions; in addition, the fineness of the composite fiber after lamination is 3D-5D, and the basis weight is 1200-1500g / m².2 .

[0049] In some specific examples, in the above preparation method, (i) The steam forming pressure is 14-17 Bar, such as 15 Bar or 16 Bar; and / or (ii) Based on (i), the steam forming time is 13s-20s, such as 14s, 15s, 16s, 17s, 18s or 19s, etc. (iii) The temperature of the steam forming process is 200℃-210℃, such as 203℃, 205℃ or 207℃.

[0050] It should be noted that in this invention, if the steam pressure is less than 14 Bar, molding is impossible and the tensile strength is greatly reduced; in addition, the steam time is 13s-20s, which is too short to form and too long to significantly reduce the acoustic effect of the product; furthermore, the steam temperature is 200℃-210℃, which is too high to carbonize and make the fibers brittle, and too low to form.

[0051] To better understand the present invention, specific examples are provided below to further illustrate the content of the present invention, but the content of the present invention is not limited to the examples below.

[0052] Preparation Examples In this embodiment, there are no restrictions on the preparation methods of PET and COPET used. Existing technologies can be used as long as the melting point and intrinsic viscosity requirements are met, such as existing technologies CN105077898B, CN113308802A, CN113403755A, and CN113417029B.

[0053] Example 1 (1) COPET and PET are melted separately. The melting temperature of COPET is 270℃ and the melting temperature of PET is 280℃. Among them, the melting point of PET is 260℃ and the intrinsic viscosity of PET is 0.68dL / g; the melting point of COPET is 240℃ and the intrinsic viscosity of COPET is 0.65dL / g; the mass ratio of PET to COPET is 7:3.

[0054] (2) The molten COPET and PET were fed into a coaxial electrospinning machine for spinning to obtain COPET-coated PET composite fibers. The spinning temperature was 280℃. The electrospinning parameters were set as follows: metal nozzle diameter: shell layer 1.06mm, core layer 0.24mm; distance between copper receiving plate and nozzle 10cm; voltage 10kV; microsyringe push speed: shell layer 0.17mL / h, core layer 0.7mL / h. (3) The COPET-coated PET composite fiber was cooled and molded at 130°C. The average fineness of the cooled and molded composite fiber was 4D and the basis weight was 159g / m². 2 ; (4) The cooled composite fibers are laid into a web, and then spunbonded into a base fabric; then the base fabric is cross-laid at 45° to obtain an overlapping base fabric with a basis weight of 1428 g / m. 2 The average fineness of the composite fiber is 4D; (5) The fiber felt semi-finished product is obtained by performing the first needle entanglement and the second needle entanglement; (6) Cut the semi-finished fiber felt into 10cm×10cm sizes, and steam-form the cut fiber felt to obtain the finished fiber felt; wherein, the steam pressure is 15 Bar, the steam time is 15s, and the steam temperature is 200℃; the basis weight of the finished fiber felt is 1200g / m². 2 The thickness is 2mm.

[0055] Example 2 Example 2 is largely the same as Example 1, except that the mass ratio of PET to COPET is different, otherwise it is the same as Example 1; wherein, in Example 2, the mass ratio of PET to COPET is 9.5:0.5.

[0056] Example 3 Example 3 is largely the same as Example 1, except that the mass ratio of PET to COPET is different, otherwise it is the same as Example 1; wherein, in Example 3, the mass ratio of PET to COPET is 9:1.

[0057] Example 4 Example 4 is largely the same as Example 1, except that the mass ratio of PET to COPET is different, otherwise it is the same as Example 1; wherein, in Example 4, the mass ratio of PET to COPET is 8:2.

[0058] Example 5 Example 5 is largely the same as Example 1, except that in step (1) of Example 5, when PET is melted, 10% polyamide PA12 (accounting for 10% of the mass of PET) is added for mixing and melting; in step (2), the mixed and melted PET-PA12 and COPET are respectively fed into a coaxial electrospinning machine for spinning (spinning parameters are the same as in Example 1) to obtain a composite fiber of COPET coated with PET-PA12; the spinning temperature is 280℃; other aspects are the same as in Example 1.

[0059] Example 6 Example 6 is largely the same as Example 1, except that in step (1) of Example 6, when COPET is melted, 10% by mass of EPR material (Sinopec Mitsui, 2032PM, EPDM) (accounting for 10% of the mass of COPET) is added for mixing and melting; in step (2), the molten PET and COPET-EPR are respectively fed into a coaxial electrospinning machine for spinning (spinning parameters are the same as in Example 1) to obtain composite fibers of COPET-EPR coated with PET; the spinning temperature is 280℃, and the others are the same as in Example 1.

[0060] Example 7 Example 7 is largely the same as Example 1, except that in step (1) of Example 7, when PET is melted, 5% polyamide PA12 (accounting for 5% of the mass of PET) is added and mixed and melted; when COPET is melted, 5% EPR material (Sinopec Mitsui, 2032PM, EPDM) (accounting for 5% of the mass of COPET) is added and mixed and melted; in step (2), the mixed and melted PET-PA12 and the mixed and melted COPET-EPR are respectively fed into a coaxial electrospinning machine for spinning (spinning parameters are the same as in Example 1) to obtain a composite fiber of COPET-EPR coated with PET-PA12; the spinning temperature is 280℃, and the others are the same as in Example 1.

[0061] Example 8 Example 8 is largely the same as Example 1, except that color masterbatch was added to the PET during melting in Example 8. The amount of color masterbatch added was 2% of the mass of PET, and the color masterbatch was PET containing 30% graphite by mass. Everything else was the same as in Example 1.

[0062] Example 9 Example 9 is largely the same as Example 1, except that Example 9 uses 100% recycled PET (the intrinsic viscosity of PET is 0.55 dL / g) to replace the PET in Example 1, and at the same time, 5% by mass (accounting for 5% of the mass of PET) of chain extender 4300: Joncryl ADR-4300, BASF, is added during melting, so that the viscosity of 100% recycled PET is 0.75 dL / g. The rest is the same as Example 1.

[0063] Example 10 Example 10 is largely the same as Example 1, except that 5% by mass (accounting for 5% of the COPET mass) of water-blocking agent (Furex-6110, Guangdong Demei Fine Chemical Group Co., Ltd.) is added to the COPET during melting in Example 10. Otherwise, it is the same as Example 1.

[0064] Example 11 Example 11 is largely the same as Example 1, except that 2% by mass (2% of the mass of COPET) of flame retardant (OPR-950T) is added to the COPET during melting in Example 11. Otherwise, it is the same as Example 1.

[0065] Example 12 Example 12 is largely the same as Example 7, except that the steam pressure and steam time are different. In Example 12, the steam pressure is 14 Bar and the steam time is 20 seconds.

[0066] Example 13 Example 13 is largely the same as Example 7, except that the steam pressure and steam time are different, while the rest are the same as Example 1; wherein, the steam pressure in Example 13 is 17 Bar and the steam time is 13 s.

[0067] Comparative Example 1 Comparative Example 1 is largely the same as Example 1, except that the PET material is different. Otherwise, it is the same as Example 1. In Comparative Example 1, the melting point of PET is 255°C and the intrinsic viscosity of PET is 0.63 dL / g.

[0068] Comparative Example 2 Comparative Example 2 is largely the same as Example 7, except that the steam pressure and steam time are different, otherwise the same as Example 7; wherein, the steam pressure in Comparative Example 2 is 12 Bar and the steam time is 20 s.

[0069] Comparative Example 3 Comparative Example 3 is largely the same as Example 7, except that the steam pressure and steam time are different, otherwise the same as Example 7; wherein, the steam pressure in Comparative Example 3 is 17 Bar and the steam time is 11 s.

[0070] Comparative Example 4 Comparative Example 4 is largely the same as Example 7, except that the steam pressure and steam time are different, otherwise the same as Example 7; wherein, the steam pressure in Comparative Example 4 is 17 Bar and the steam time is 25 s.

[0071] Comparative Example 5 Comparative Example 5 is largely the same as Example 7, except that the steam temperature is different, otherwise it is the same as Example 7; wherein, the steam temperature in Comparative Example 5 is 220°C.

[0072] Performance testing (a) Mechanical and acoustic performance testing The tensile strength and tear strength of the fiber felt products prepared in the examples and comparative examples were tested according to GB / T 529-2008; the sound absorption coefficient (2500HZ) of the fiber felt products prepared in the examples and comparative examples were tested according to GB / T18696.2-2002. The test results are shown in Table 1 below.

[0073] Table 1. Mechanical and acoustic properties of the fiber felt products prepared in the examples and comparative examples. As can be seen from Table 1 above, the tensile strength and tear strength of the fiber felt products prepared in Examples 1 to 13 are significantly higher than those in Comparative Examples 1 to 4.

[0074] Comparing Example 1 and Comparative Example 1, it can be seen that the intrinsic viscosity of PET in Comparative Example 1 is lower than that of COPET, and the tensile strength, tear strength and 2500HZ sound absorption coefficient of the prepared fiber felt are lower than those of Example 1, especially the sound absorption coefficient is significantly reduced.

[0075] Comparing Examples 1 and 2 to 4, it can be seen that: if too little shell (COPET) is added, the final felt will have poor formability and a sharp decrease in tensile strength. The average tensile strength will drop from 34.9 MPa (Example 1) to about 15.3 MPa (Example 2), and the tear strength will also drop from 299.8 N (Example 1) to about 107.2 N (Example 2).

[0076] Comparing Comparative Examples 1 and 5 to 7 reveals that, based on Example 1, Examples 5 and 7 respectively added polyamide PA12 to the high-melting-point PET core layer and EPR material to the low-melting-point COPET sheath layer, both of which significantly improved the sound absorption coefficient of the felt sample compared to Example 1. When polyamide PA12 is added to the core layer and EPR material is added to the sheath layer simultaneously, the two can work synergistically to further improve the sound absorption coefficient of the felt sample.

[0077] Comparing Comparative Example 1 and Example 8, it can be seen that: Based on Example 1, Example 8 added 2% by mass of color masterbatch (PET containing 30% by mass of graphite) to the core layer (PET). The results show that the addition of color masterbatch does not significantly change the mechanical properties and sound absorption properties of the felt sample.

[0078] Comparing Comparative Example 1 and Example 9, it can be seen that Example 9 used 100% recycled PET (viscosity 0.57 dL / g), and then increased the viscosity to 0.75 dL / g by adding 5% by mass of chain extender (chain extender 4300: Joncryl ADR-4300, BASF). The results show that the tensile strength, tear strength, and 2500HZ sound absorption coefficient of the felt product prepared by increasing the viscosity through chain extender (chain extender 4300: Joncryl ADR-4300, BASF) did not show a significant decrease.

[0079] Comparing Example 1 and Example 10, it can be seen that: Example 10, based on Example 1, adds 5% by mass of water-blocking agent to the core layer (PET), which can prevent the product from absorbing water. Moreover, the addition of water-blocking agent does not significantly affect the tensile strength, tear strength, or 2500HZ sound absorption coefficient of the finished felt product.

[0080] Comparing Example 1 and Example 11, it can be seen that: Based on Example 1, Example 11 adds 2% by mass of flame retardant (OPR-950T) to the shell (COPET), which can improve the flame retardant performance of the product. Moreover, the addition of flame retardant does not significantly affect the tensile strength, tear strength, or 2500HZ sound absorption coefficient of the finished felt.

[0081] Comparing Examples 1 and 12 to 13, it can be seen that Examples 12 and 13 changed the steam pressure and steam time based on Example 1. The results show that when the steam control pressure is greater than or equal to 14 Bar-17 Bar, the steam time is 13 s-20 s, and the steam temperature is 200℃, the prepared felt products all have good tensile strength, tear strength, and a sound absorption coefficient of 2500 Hz.

[0082] A comparison of Example 7 and Comparative Examples 2 to 4 reveals that, based on Example 7, adjustments to the steam pressure and / or steam time in Comparative Examples 2 to 4 significantly reduced the mechanical properties of the prepared felt when the steam pressure and / or steam time exceeded the range of the present invention. Specifically, at a steam pressure of 12 Bar (<14 Bar) and a steam time of 20 s, the felt could not be formed, and the tensile strength decreased from 36.2 MPa to approximately 15.7 MPa (Comparative Example 2); at a steam pressure of 17 Bar and a steam time of 25 s, the prepared felt lost its acoustic properties, and the sound absorption coefficient in the high-frequency range (above 2500 Hz) decreased from above 0.8 to below 0.5 (Comparative Example 4).

[0083] Furthermore, comparing Example 7 and Comparative Example 5, it can be seen that the steam temperature in Comparative Example 5 is 220°C, based on Example 7. The results show that when the steam temperature is greater than 210°C, the fiber carbonizes and becomes brittle due to the high temperature, and the tensile strength, tear strength and sound absorption coefficient all decrease significantly.

[0084] (ii) Sound absorption coefficient test at different frequencies According to GB / T18696.2—2002, the sound absorption coefficients of the fiber felt products prepared in Example 1, Examples 6 to 7 and Comparative Example 6 at different frequencies were tested respectively, and the test results are shown in Table 2 below.

[0085] Table 2 Sound absorption coefficients of the fiber felt products prepared in Examples 1, 5 to 7 and Comparative Examples 1 and 4 As shown in Table 2 above, the sound absorption coefficients of the fiber felt products prepared in Examples 1, 5 to 7 at different frequencies are significantly higher than those prepared in Comparative Examples 1 and 4; wherein: Comparing Example 1 and Comparative Example 1, it can be seen that the intrinsic viscosity of PTE in Comparative Example 1 is lower than that of COPET, and the sound absorption coefficient of the prepared fiber felt product at different frequencies is significantly lower than that in Example 1.

[0086] Comparing Examples 1 and 5 to 7, it can be seen that Examples 5 and 7, based on Example 1, respectively added polyamide PA12 to the high-melting-point PET core layer and EPR material to the low-melting-point COPET sheath layer, which can significantly improve the sound absorption coefficient of the felt sample at different frequencies compared to Example 1. When polyamide PA12 is added to the core layer and EPR material is added to the sheath layer at the same time, the two can work together to further improve the sound absorption coefficient of the felt sample at different frequencies. Comparing Example 7 and Comparative Example 4, it can be seen that Comparative Example 4 is based on Example 7, but with the steam pressure adjusted to 17 Bar and the steam time to 25 s. The results show that the sound absorption coefficient of the felt product prepared under these conditions is significantly reduced at different frequencies.

[0087] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A fiber composite material with a core-sheath structure, comprising a core layer and a sheath layer, characterized in that, The core layer contains PET, which has a melting point of 250℃-260℃ and an intrinsic viscosity of 0.68dL / g-0.80dL / g. The sheath contains COPET, which has a melting point of 230℃-240℃ and an intrinsic viscosity of 0.64dL / g-0.68dL / g; the intrinsic viscosity of PET is greater than that of COPET.

2. The fiber composite material according to claim 1, characterized in that, PET is obtained by adding chain extenders to recycled PET; the intrinsic viscosity of recycled PET is <0.68 dL / g; and / or COPET is obtained by copolymerizing polyethylene isophthalate and polyethylene terephthalate.

3. The fiber composite material according to claim 1 or 2, characterized in that The mass of the sheath is 10%-30% of the total mass of the core and sheath.

4. The fiber composite material according to claim 3, characterized in that The mass of the sheath is 30% of the total mass of the core and sheath.

5. The fiber composite material according to claim 1, 2, or 4, characterized in that, The core layer also includes color masterbatch and / or PA material; and / or The sheath also contains one or more of a water barrier, a flame retardant, or an EPR material.

6. The fiber composite material according to claim 5, characterized in that, The color masterbatch is PET containing 25%-35% graphite by mass; and / or The water-blocking agent is selected from fluorinated acrylate copolymers and / or non-fluorinated acrylate copolymers; and / or The flame retardant is selected from one or more combinations of alkyl phosphinic acid metal salts, phosphinic acid organic amine salts, or phosphinic acids. PA materials are selected from one or more combinations of PA6, PA66, PA11 or PA12.

7. The fiber composite material according to claim 5, characterized in that, The mass of the color masterbatch is 1%-3% of the PET mass; and / or The mass of PA material is 1%-10% of the mass of PET; and / or The water-blocking agent is 1%-10% of the COPET mass; and / or The flame retardant is 1%-3% of the COPET mass; and / or The mass of EPR material is 5%-15% of the mass of COPET.

8. The method of producing a fiber composite material according to any one of claims 1 to 7, characterized in that, Preparation methods include: (1) The molten sheath and core are fed into a coaxial electrospinning machine for spinning to obtain a composite fiber with sheath covering the core. The spinning temperature is 270℃-300℃. (2) The composite fiber with sheath covering core layer is cooled and molded at 120℃-140℃ to obtain fiber composite material.

9. A fibrous mat characterized by, The fiber composite material according to any one of claims 1 to 6 is produced from a fiber mat having a thickness of 2 mm to 4 mm and a grammage of 800 g / m 2 - 2000 g / m 2 .

10. The method of making a fibrous mat of claim 9, characterized in that, Preparation methods include: (1) The composite fibers are laid into a web and spunbonded to obtain the base fabric; (2) The base fabric is cross-laid at 45° to obtain an overlapping base fabric; (3) The overlapping base fabric is needle-punched and entangled at least once to obtain a fiber felt semi-finished product; (4) The fiber felt semi-finished product is steam-formed to obtain fiber felt. in, (i) The steam forming process is performed at a pressure of 14-17 Bar; and / or (ii) Based on (i), the steam forming process time is 13s-20s; and / or (iii) The temperature of the steam forming process is 200℃-210℃.

Images