Special fiber composite material with ultrahigh mechanical property and preparation method thereof

Abstract

The invention belongs to the technical field of fiber materials, and particularly relates to a special fiber composite material with ultrahigh mechanical properties and a preparation method thereof. The special fiber composite material comprises a fiber composition, and the fiber composition comprises PET short fibers with the melting point of 250-260 DEG C, PET short fibers with the melting point of 160-200 DEG C and PET short fibers with the melting point of 110-130 DEG C. Experimental verification shows that the tensile strength of the fiber composite material can be synergistically increased by the PET short fibers with the three different melting points, and the tensile strength of the fiber composite material is remarkably higher than that of the fiber composite material prepared from the PET short fibers with the two melting points.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of fiber materials, and particularly relates to a special fiber composite material with super-high mechanical properties and a preparation method thereof. BACKGROUND

[0002] As a kind of high-performance synthetic fiber, polyethylene terephthalate (PET) fiber has become one of the core raw materials in the field of fiber composites due to its excellent mechanical strength, chemical corrosion resistance and cost-effectiveness, and is widely used in automobile industry, construction engineering, filtration and separation, home textiles and other fields. In practical applications, the tensile strength of composite materials is a key indicator that determines the structural load-bearing capacity and service life, and directly affects the reliability of materials under complex conditions such as dynamic load and environmental stress. At present, the technical path to improve the tensile strength of PET fiber composites mainly includes optimizing the microstructure of the fiber (such as crystallinity, orientation), improving the molding process parameters (such as temperature, pressure) and adjusting the interfacial bonding performance of the fiber and the matrix, etc., among which the control of the fiber performance is the most direct and economical optimization method.

[0003] Although the application of PET fiber composites is relatively mature, there are still significant bottlenecks in improving their tensile strength in the existing technology. On the one hand, single performance parameter PET fibers cannot balance the processing adaptability and final mechanical properties during the composite forming process: for example, high-rigidity fibers can provide structural support, but have poor interfacial compatibility with the matrix, which easily leads to stress concentration; while flexible fibers have strong interfacial adhesion, but may lose structural stability due to excessive melting. On the other hand, existing methods to improve strength mostly rely on external modification methods, such as adding inorganic nano-fillers (such as glass fibers, carbon fibers) or chemical grafting modification, which not only increases the process complexity and production cost, but also may cause uneven dispersion of fibers, degradation of the matrix and other side effects, limiting the comprehensive performance improvement of the material. In addition, some technologies simply increase the fiber content to enhance the strength, but beyond the critical proportion, it easily leads to an increase in internal defects of the composite material, which in turn reduces the overall mechanical properties.

[0004] In view of the current technical situation that the tensile strength of existing PET fiber composites is difficult to break through, it is necessary to develop a scheme that can improve the strength of PET fibers without relying on external modifiers or complex processes. SUMMARY

[0005] Based on this, the present invention provides a special fiber composite material with ultra-high mechanical properties and its preparation method. Specifically, the present invention has experimentally verified that three PET short fibers with different melting points can synergistically increase the tensile strength of the fiber composite material. Its tensile strength is significantly higher than that of the fiber composite material prepared from two of the PET short fibers with different melting points, and it can achieve the improvement of tensile strength without relying on external modifiers or complex processes.

[0006] To achieve the above objectives, the present invention can adopt the following technical solutions: This invention provides a special fiber composite material with ultra-high mechanical properties. The special fiber composite material includes a fiber composition, which comprises: PET short fibers with a melting point of 250℃~260℃; PET short fibers with a melting point of 160℃~200℃; PET short fibers with a melting point of 110℃~130℃; The fineness of PET short fibers with different melting points ranges from 3D to 6D, and their lengths range from 7mm to 25mm.

[0007] Preferably, in the above-mentioned special fiber composite material, the fiber composition comprises, by mass fraction: PET staple fiber with a melting point of 250℃~260℃: 40%~80%; PET staple fiber with a melting point of 160℃~200℃: 10%~30%; PET short fibers with a melting point of 110℃~130℃: 10%~30%.

[0008] More preferably, in the above-mentioned special fiber composite material, the fiber composition, by mass fraction, comprises: PET staple fiber with a melting point of 250℃~260℃: 50%~70%; PET staple fiber with a melting point of 160℃~200℃: 15%~25%; PET short fibers with melting point of 110℃~130℃: 15%~25%.

[0009] More preferably, in the above-mentioned special fiber composite material, the fiber composition, by mass fraction, comprises: PET staple fiber with a melting point of 260℃: 60%; PET staple fiber with a melting point of 180℃: 20%; PET staple fiber with a melting point of 110℃: 20%.

[0010] Preferably, the above-mentioned special fiber composite material further includes polyurethane and / or calcium carbonate.

[0011] More preferably, in special fiber composite materials, When the special fiber composite material also includes polyurethane, the mass ratio of the fiber composition to the polyurethane is 1:(0.05~0.1). When the special fiber composite material also includes calcium carbonate, the mass ratio of the fiber composition to calcium carbonate is 1:(0.01~0.05). When the special fiber composite material also includes polyurethane and calcium carbonate, the mass ratio of the fiber composition, calcium carbonate and polyurethane is 1:(0.01~0.05):(0.05~0.1).

[0012] Another aspect of the present invention provides a method for preparing the special fiber composite material of the present invention: When special fiber composite materials include fiber compositions, their preparation methods include: (1) The fiber composition is sequentially opened and mixed in a bulk bin to obtain mixed fibers; (2) The mixed fibers are subjected to an injection fiber process to obtain preheated mixed fibers; (3) The preheated mixed fibers are subjected to high-temperature steam thermoforming treatment and cooled to obtain special fiber composite materials; When the special fiber composite material includes a fiber composition and polyurethane and / or calcium carbonate, its preparation method includes: (1) The fiber composition is sequentially opened and mixed in a bulk bin to obtain mixed fibers; (2) The mixed fibers are subjected to an injection fiber process to obtain preheated mixed fibers; (3) The preheated mixed fibers, polyurethane and / or calcium carbonate are subjected to high-temperature steam thermoforming treatment and cooled to obtain special fiber composite materials.

[0013] Preferably, in the above preparation method, In step (2), the temperature of the fiber injection process is 70℃~150℃; and / or In step (3), the temperature of the high-temperature steam thermoforming treatment is 150℃~190℃.

[0014] More preferably, in the above preparation method, In step (2), the temperature of the fiber injection process is 80℃~140℃; and / or In step (3), the temperature of the high-temperature steam thermoforming treatment is 160℃~180℃.

[0015] The beneficial effects of this invention include: the combination of high-melting-point (250℃~260℃) PET short fibers, medium-melting-point (160℃~200℃) PET short fibers, and low-melting-point (110℃~130℃) PET short fibers can synergistically increase the tensile strength of fiber composite materials. Specifically, experimental verification shows that the tensile strength of fiber composite materials prepared by combining only high-melting-point and medium- or low-melting-point PET short fibers is 15MPa~20MPa, the tensile strength of fiber composite materials prepared by combining only medium- or low-melting-point PET short fibers is <10MPa, and the tensile strength of fiber composite materials prepared by combining high-melting-point, medium-melting-point, and low-melting-point PET short fibers can reach 25MPa~30MPa. That is, the tensile strength of fiber composite materials prepared by the three different melting points of PET short fibers in this invention is significantly higher than that of fiber composite materials prepared by two melting points of PET short fibers. Detailed Implementation

[0016] The illustrated embodiments are provided to better illustrate the present invention, but are not intended to limit the scope of the invention to the illustrated embodiments. Therefore, non-essential improvements and adjustments made to the embodiments by those skilled in the art based on the above description of the invention still fall within the protection scope of the present invention.

[0017] 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.

[0018] Although the application of PET fiber composites is relatively mature, existing technologies still face significant bottlenecks in improving their tensile strength. On the one hand, PET fibers with single performance parameters struggle to balance processing adaptability during composite molding with final mechanical properties. For example, while high-rigidity fibers provide structural support, their poor interfacial compatibility with the matrix can easily lead to stress concentration; while flexible fibers, although possessing strong interfacial bonding, may lose structural stability due to excessive melting. On the other hand, existing methods for improving strength largely rely on external modification, such as adding inorganic nanofillers (e.g., glass fiber, carbon fiber) or chemical grafting. These approaches not only increase process complexity and production costs but may also cause side effects such as uneven fiber dispersion and matrix degradation, limiting the overall performance improvement of the material. Furthermore, some technologies enhance strength by simply increasing the fiber content, but exceeding a critical ratio can easily lead to increased internal defects in the composite material, ultimately reducing overall mechanical properties.

[0019] Based on this, the present invention can adopt the following technical solution: In a first aspect, embodiments of the present invention provide a special fiber composite material with ultra-high mechanical properties. The special fiber composite material includes a fiber composition comprising: PET short fibers with a melting point of 250℃~260℃; PET short fibers with a melting point of 160℃~200℃; PET short fibers with a melting point of 110℃~130℃; The fineness of PET short fibers with different melting points ranges from 3D to 6D, and their lengths range from 7mm to 25mm.

[0020] It should be noted that PET short fibers with a melting point of 250℃~260℃ can provide strength as a base fiber material for special fiber composites, while PET short fibers with melting points of 160℃~200℃ and 110℃~130℃ can optimize the strength of the binder in special fiber composites. This invention combines high-melting-point (250℃~260℃), medium-melting-point (160℃~200℃), and low-melting-point (110℃~130℃) PET short fibers to synergistically increase the tensile strength of fiber composites. Specifically, experimental verification shows that the tensile strength of fiber composites prepared by combining only high-melting-point and medium- or low-melting-point PET short fibers is 15MPa~20MPa, the tensile strength of fiber composites prepared by combining only medium- or low-melting-point PET short fibers is <10MPa, and the tensile strength of fiber composites prepared by combining high-melting-point, medium-melting-point, and low-melting-point PET short fibers can reach 25MPa~30MPa. That is, the tensile strength of fiber composites prepared by the three different melting points of PET short fibers in this invention is significantly higher than that of fiber composites prepared by two different melting points of PET short fibers.

[0021] Furthermore, the PET short fibers with different melting points used in this invention are well-known in the art. The high-melting-point PET is the commonly used PET in the art, namely polyethylene terephthalate, with a melting point of 250℃~260℃ and an intrinsic viscosity of 0.65dL / g~0.85dL / g. The two low-melting-point fibers have intrinsic viscosities of 0.54dL / g~0.72dL / g and are copolymerized from polyethylene isophthalate and polyethylene terephthalate in a certain proportion. The introduction of [a certain substance] can adjust the melting point, and its preparation method is well known in the art. For example, it can be prepared by referring to the preparation method of "low melting point polyester material" described in patent CN119710977A. It should be understood that, in addition to being prepared by referring to existing patents, different low melting point PETs have also been disclosed in the prior art, such as "PET3" described in patent CN1930344B or "low melting point PET copolymer" described in patent CN115806728B.

[0022] Furthermore, the fineness of PET staple fibers with different melting points can range from 3D to 6D (e.g., 3.5D, 4D, 4.5D, 5D, or 5.5D), and the length can range from 7mm to 25mm (e.g., 10mm, 15mm, 17mm, 20mm, or 23mm). It should be understood that the fineness and length of PET staple fibers can be processed according to specific requirements and methods described in existing technologies.

[0023] In some specific examples, the fiber composition in the above-mentioned special fiber composite material comprises, by mass fraction: PET staple fiber with a melting point of 250℃~260℃: 40%~80%; PET staple fiber with a melting point of 160℃~200℃: 10%~30%; PET short fibers with a melting point of 110℃~130℃: 10%~30%.

[0024] It should be noted that, as mentioned above, the high-melting-point PET short fibers serve as the base fibers, while the medium- and low-melting-point fibers can be used as bonding materials. Therefore, the combination ratio of these three components affects the mechanical properties (tensile strength) of the prepared special fiber composite material. In this invention, the mass percentages of high-melting-point (melting point 250℃~260℃), medium-melting-point (160℃~200℃), and low-melting-point (110℃~130℃) PET short fibers can be 40%~80%, 10%~30%, and 10%~30%, respectively, for example, 50%, 25%, 25%; 60%, 20%, 20%; 70%, 15%, 15%, etc.

[0025] In some specific examples, the fiber composition in the above-mentioned special fiber composite material comprises, by mass fraction: PET staple fiber with a melting point of 250℃~260℃: 50%~70%; PET staple fiber with a melting point of 160℃~200℃: 15%~25%; PET short fibers with melting point of 110℃~130℃: 15%~25%.

[0026] It should be noted that the mass ratio of the three PET short fibers with different melting points in the fiber composition of the special fiber composite material of the present invention can preferably be the mass ratio listed above, and the fiber composite material prepared with this mass ratio has better mechanical properties.

[0027] In some specific examples, the fiber composition in the above-mentioned special fiber composite material comprises, by mass fraction: PET staple fiber with a melting point of 260℃: 60%; PET staple fiber with a melting point of 180℃: 20%; PET staple fiber with a melting point of 110℃: 20%.

[0028] It should be noted that the special fiber composite material with the mass ratio listed above is more preferred in this invention, and the tensile strength of the special fiber composite material prepared with the mass ratio can reach 29.8 MPa.

[0029] In some specific examples, the aforementioned special fiber composite materials also include polyurethane and / or calcium carbonate.

[0030] It should be noted that the fiber composition of the present invention can also be combined with polyurethane to prepare a special fiber composite material with excellent sound absorption properties; in addition, the fiber composition of the present invention can also be combined with calcium carbonate to prepare a special fiber composite material with excellent flexural strength, which can be increased by about 10% compared with the fiber composition without added calcium carbonate. Furthermore, it should be understood that polyurethane and calcium carbonate can be used in combination with the fiber composition to improve sound absorption and mechanical properties.

[0031] In some specific examples, in special fiber composite materials, When the special fiber composite material also includes polyurethane, the mass ratio of the fiber composition to the polyurethane is 1:(0.05~0.1). When the special fiber composite material also includes calcium carbonate, the mass ratio of the fiber composition to calcium carbonate is 1:(0.01~0.05). When the special fiber composite material also includes polyurethane and calcium carbonate, the mass ratio of the fiber composition, calcium carbonate and polyurethane is 1:(0.01~0.05):(0.05~0.1).

[0032] It should be noted that when the fiber composition is used in combination with polyurethane and / or calcium carbonate, the mass ratio can preferably be one of the mass ratios listed above. For example, when the special fiber composite material also includes polyurethane, the mass ratio of the fiber composition to polyurethane can preferably be 1:(0.05 to 0.1), such as 1:0.06, 1:0.07, 1:0.08, or 1:0.09; as another example, when the special fiber composite material also includes calcium carbonate, the mass ratio of the fiber composition to calcium carbonate can preferably be 1:(0.01 to 0.05), such as 1:0.02, 1:0.03, or 1:0.04; as yet another example, when the special fiber composite material also includes polyurethane and calcium carbonate, the mass ratio of the fiber composition, calcium carbonate, and polyurethane is 1:0.02:0.07, 1:0.03:0.09, or 1:0.04:0.09.

[0033] Secondly, embodiments of the present invention provide a method for preparing the special fiber composite material of the present invention: When special fiber composite materials include fiber compositions, their preparation methods include: (1) The fiber composition is sequentially opened and mixed in a bulk bin to obtain mixed fibers; (2) The mixed fibers are subjected to an injection fiber process to obtain preheated mixed fibers; (3) The preheated mixed fibers are subjected to high-temperature steam thermoforming treatment and cooled to obtain special fiber composite materials; When the special fiber composite material includes a fiber composition and polyurethane and / or calcium carbonate, its preparation method includes: (1) The fiber composition is sequentially opened and mixed in a bulk bin to obtain mixed fibers; (2) The mixed fibers are sequentially subjected to the fiber injection process to obtain preheated mixed fibers; (3) The preheated mixed fibers, polyurethane and / or calcium carbonate are subjected to high-temperature steam thermoforming treatment and cooled to obtain special fiber composite materials.

[0034] It should be noted that the terms "opening", "large-scale mixing", "injection fiber process" and "high-temperature steam thermoforming treatment" in the above preparation methods are all conventional operating methods known in the field and have no specific meaning.

[0035] In some specific examples, in the above preparation method, In step (2), the temperature of the fiber injection process is 70℃~150℃; and / or In step (3), the temperature of the high-temperature steam thermoforming treatment is 150℃~190℃.

[0036] It should be noted that in the above preparation method, the temperature of the injection molding process and the temperature of the high-temperature steam thermoforming treatment can be synergistically adjusted to improve the mechanical properties of the prepared special fiber composite material. Preferably, the temperature of the injection molding process in this invention is 70℃~150℃ (e.g., 90℃, 110℃, or 130℃), while the temperature of the high-temperature steam thermoforming treatment is 150℃~190℃ (e.g., 160℃, 170℃, or 180℃). The mechanical properties of the special fiber composite material prepared at this synergistic temperature are superior to those at other temperatures.

[0037] In some specific examples, in the above preparation method, In step (2), the temperature of the fiber injection process is 80℃~140℃; and / or In step (3), the temperature of the high-temperature steam thermoforming treatment is 160℃~180℃.

[0038] It should be noted that the temperatures of the injection fiber process and the high-temperature steam thermoforming treatment in this invention can be further optimized by the temperatures listed above, and more preferably the temperature of the injection fiber process is 80°C and the temperature of the high-temperature steam thermoforming treatment is 180°C, resulting in more superior mechanical properties of the special fiber composite material.

[0039] 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.

[0040] Preparation Examples In the following examples, the PET staple fiber with a melting point of 260℃ comes from Shanghai Petrochemical; the PET staple fiber with a melting point of 180℃ is polymerized from polyethylene terephthalate and polyethylene isophthalate, with a molar ratio of 1:0.4; the PET staple fiber with a melting point of 110℃ is polymerized from polyethylene terephthalate and polyethylene isophthalate, with a molar ratio of 1:0.2.

[0041] Example 1 (1) Three types of PET staple fibers are prepared according to the following mass ratio: PET staple fiber with a melting point of 260℃ (4D fineness, 15mm length): 60%; PET staple fiber with a melting point of 180℃ (4D fineness, 15mm length): 20%; PET staple fiber with a melting point of 110℃ (4D fineness, 15mm length): 20%; (2) Mix the three types of PET fibers, and then perform opening and bulk mixing in sequence to obtain mixed fibers; (3) The mixed fibers are subjected to fiber injection molding (IFP) process, wherein the heating temperature is 80°C, to obtain preheated mixed fibers; the preheated mixed fibers are kept at the heating temperature by a hot air oven; (4) The preheated mixed fibers are thermoformed using high-temperature steam. The steam temperature is 180°C, the steam time is 15s, and the steam pressure is 12Bar. Then, they are placed in a mold and pressurized (pressure 10 MPa, holding time 30s). After pressurization, they are cooled to 60°C and then demolded. The edges are cut and punched to obtain the finished fiber felt, i.e., special fiber composite material.

[0042] Example 2 Example 2 is largely the same as Example 1, except that the configuration of the short fibers is different. Otherwise, it is the same as Example 1, and a fiber felt product is prepared. The configuration of the short fibers in Example 2 is as follows: PET staple fiber with a melting point of 260℃ (4D fineness, 15mm length): 40%; PET staple fiber with a melting point of 180℃ (4D fineness, 15mm length): 30%; PET staple fiber with melting point of 110℃ (fineness 4D, length 15mm): 30%.

[0043] Example 3 Example 3 is largely the same as Example 1, except that the configuration of the short fibers is different. Otherwise, it is the same as Example 1, and a fiber felt product is prepared. The configuration of the short fibers in Example 3 is as follows: PET staple fiber (4D fineness, 15mm length) with a melting point of 260℃: 50%; PET staple fiber with a melting point of 180℃ (4D fineness, 15mm length): 25%; PET staple fiber with melting point of 110℃ (fineness 4D, length 15mm): 25%.

[0044] Example 4 Example 4 is largely the same as Example 1, except that the configuration of the short fibers is different. Otherwise, it is the same as Example 1, and a fiber felt product is prepared. The configuration of the short fibers in Example 4 is as follows: PET staple fiber with a melting point of 260℃ (4D fineness, 15mm length): 70%; PET staple fiber with a melting point of 180℃ (4D fineness, 15mm length): 15%; PET short fibers with a melting point of 110℃ (fineness 4D, length 15mm): 15%.

[0045] Example 5 Example 5 is largely the same as Example 1, except that the configuration of the short fibers is different. Otherwise, it is the same as Example 1, and a fiber felt product is prepared. The configuration of the short fibers in Example 5 is as follows: PET staple fiber (4D fineness, 15mm length) with a melting point of 260℃: 80%; PET staple fiber with a melting point of 180℃ (4D fineness, 15mm length): 10%; PET staple fiber with melting point of 110℃ (fineness 4D, length 15mm): 10%.

[0046] Example 6 Example 6 is largely the same as Example 1, except that the raw materials in step (4) are different, while the rest is the same as in Example 1, and the fiber felt product is prepared. In Example 6, the raw materials in step (4) also include polyurethane (Covestro 9380A). In the raw materials in step (4), the mass ratios of preheated mixed fiber and polyurethane are 90% and 10%, respectively.

[0047] Example 7 Example 7 is largely the same as Example 6, except that in step (4) of Example 7, polyamide (PA6) PA is used to replace the polyurethane in Example 1. Otherwise, the same as Example 1 is used to prepare the finished fiber felt.

[0048] Example 8 Example 8 is largely the same as Example 6, except that in step (4) of Example 8, polypropyleneimide (PPI) is used instead of polyurethane in Example 1. Otherwise, the same as in Example 1 is used to prepare the finished fiber felt.

[0049] Example 9 Example 9 is largely the same as Example 1, except that the raw materials in step (4) are different, while the rest is the same as in Example 1, and the fiber felt product is prepared. In Example 9, the raw materials in step (4) also include calcium carbonate. In the raw materials in step (4), the mass ratios of preheated mixed fiber and calcium carbonate are 95% and 5%, respectively.

[0050] Example 10 Example 10 is largely the same as Example 1, except that the raw materials in step (4) are different, while the rest is the same as in Example 1, and the fiber felt product is prepared. In Example 11, the raw materials in step (4) also include calcium carbonate and polyurethane (Covestro 9380A). In the raw materials in step (4), the mass percentages of preheated mixed fiber, polyurethane and calcium carbonate are 90%, 5% and 5%, respectively.

[0051] Example 11 Example 11 is largely the same as Example 1, except that the heating temperature of the fiber injection process in step (3) and the high temperature steam thermoforming temperature in step (4) are different. Otherwise, they are the same as in Example 1, and the fiber felt product is prepared. In Example 11, the heating temperature of the fiber injection process in step (3) is 70°C, and the high temperature steam thermoforming temperature in step (4) is 190°C.

[0052] Example 12 Example 12 is largely the same as Example 1, except that the heating temperature of the fiber injection process in step (3) and the high temperature steam thermoforming temperature in step (4) are different. Otherwise, they are the same as in Example 1, and the fiber felt product is prepared. In Example 12, the heating temperature of the fiber injection process in step (3) is 140°C, and the high temperature steam thermoforming temperature in step (4) is 160°C.

[0053] Example 13 Example 13 is largely the same as Example 1, except that the heating temperature of the fiber injection process in step (3) and the high temperature steam thermoforming temperature in step (4) are different. Otherwise, they are the same as in Example 1, and the fiber felt product is prepared. In Example 13, the heating temperature of the fiber injection process in step (3) is 150°C, and the high temperature steam thermoforming temperature in step (4) is 150°C.

[0054] Comparative Example 1 Comparative Example 1 is largely the same as Example 1, except that the configuration of the short fibers is different. Otherwise, it is the same as Example 1, and a fiber felt product is prepared. The configuration of the short fibers in Comparative Example 1 is as follows: PET staple fiber (3D fineness, 15mm length) with a melting point of 260℃: 60%; PET staple fiber with melting point of 180℃ (fineness 3D, length 15mm): 40%.

[0055] Comparative Example 2 Comparative Example 2 is largely the same as Example 1, except that the configuration of the short fibers is different. Otherwise, it is the same as Example 1, and a fiber felt product is prepared. The configuration of the short fibers in Comparative Example 2 is as follows: PET staple fiber (3D fineness, 15mm length) with a melting point of 260℃: 60%; PET staple fiber with melting point of 110℃ (fineness 3D, length 15mm): 40%.

[0056] Comparative Example 3 Comparative Example 3 is largely the same as Example 1, except that the configuration of the short fibers is different. Otherwise, it is the same as Example 1, and a fiber felt product is prepared. The configuration of the short fibers in Comparative Example 3 is as follows: PET staple fiber (3D fineness, 15mm length) with a melting point of 180℃: 50%; PET staple fiber with melting point of 110℃ (fineness 3D, length 15mm): 50%.

[0057] Performance testing The tensile strength of the fiber felt products prepared in Examples 1 to 13 and Comparative Examples 1 to 3 were tested according to GB / T 20312-2006 Determination of Tensile Breaking Strength of Glass Fiber Mat; the flexural strength of the fiber felt products prepared in Examples 1 to 13 and Comparative Examples 1 to 3 were tested according to GB / T 9341-2008 Determination of Bending Properties of Plastics; the test results are shown in Table 1 below.

[0058] Table 1 Mechanical properties of the fiber felt products prepared in the examples / comparative examples As can be seen from Table 1 above, the tensile strength and flexural strength of the fiber felt products prepared in Examples 1 to 13 are significantly higher than those prepared in Comparative Examples 1 to 3. By comparing Example 1 with Comparative Examples 1 to 3, it can be seen that the difference between Example 1 and Comparative Examples 1 to 3 is that Example 1 uses a combination of three PET short fibers with different melting points, Comparative Example 1 uses a combination of high-melting-point and medium-melting-point PET short fibers, Comparative Example 2 uses a combination of high-melting-point and low-melting-point PET short fibers, and Comparative Example 3 uses a combination of medium-melting-point and low-melting-point PET short fibers. The results show that the tensile strength and flexural strength of the fiber felt product prepared by combining three PET short fibers with different melting points are significantly higher than those of Comparative Examples 1 to 3, especially significantly higher than those of the fiber felt product prepared by combining medium-melting-point and low-melting-point PET short fibers. A comparison of Example 1 with Examples 2 to 5 reveals that the difference between Example 1 and Examples 2 to 5 is that the mass ratio of the three PET short fibers with different melting points is different. The results show that as the mass ratio of high-melting-point PET short fibers increases (the other two ratios are 1:1), the tensile strength and flexural strength of the prepared fiber felt product first increase and then decrease. For example, when the mass ratio of high-melting-point PET short fibers in Examples 2 and 5 is 40% and 80%, respectively, the tensile strength and flexural strength of the prepared fiber felt product are lower than those in Examples 3 and 4. Therefore, in this invention, the mass ratio of high-melting-point PET short fibers can preferably be 50% or more. Comparing Example 1 with Examples 6 to 8 reveals that the difference between Example 1 and Examples 6 to 8 is that Examples 6 to 8 added polyurethane (Covestro 9380A), polyamide (PA6), and polypropyleneimide, respectively, to Example 1. The results show that the tensile strength and flexural strength of the fiber felt products prepared by adding polyurethane (Covestro 9380A), polyamide, and polypropyleneimide are significantly improved; among them, the tensile strength and flexural strength of the fiber felt products prepared by adding polyurethane (Covestro 9380A) are higher than those of the fiber felt products prepared by adding polyamide and polypropyleneimide.

[0059] Comparing Example 1 with Example 9, it can be seen that the difference between Example 1 and Example 9 is that Example 9 adds calcium carbonate to the basis of Example 1. The results show that the bending strength of the fiber felt product prepared by adding calcium carbonate is significantly improved. Comparing Example 1 with Examples 11 to 13, it can be seen that the difference between Examples 11 to 13 and Example 1 is that the heating temperature of the injection fiber process in step (3) and the high temperature steam thermoforming temperature in step (4) are different. The results show that when the heating temperature of the injection fiber process and the high temperature steam thermoforming temperature are too high or too low, the mechanical properties of the prepared fiber felt product will be affected. For example, when the heating temperature of the injection fiber process is 80℃~140℃ and the high temperature steam thermoforming temperature is 160℃~180℃ (Examples 1 and 12), the tensile strength and flexural strength of the fiber felt product prepared are significantly higher than those prepared in Example 11 (injection fiber process heating temperature is 70℃, high temperature steam thermoforming temperature is 190℃) and Example 13 (injection fiber process heating temperature is 150℃, high temperature steam thermoforming temperature is 150℃).

[0060] In addition, according to GB / T18696.2—2002 Measurement of sound absorption coefficient and acoustic impedance in acoustic impedance tubes Part 2: Transfer function method, the sound absorption coefficients of the fiber felt products prepared in Examples 1, 6 to 8, 11 and 13 and Comparative Examples 1 to 3 were tested respectively, and the results are shown in Table 2 below.

[0061] Table 2 Sound absorption coefficients of the fiber felt products prepared in the examples / comparative examples As shown in Table 2 above, the sound absorption coefficients of the fiber felt products prepared in the examples at different frequencies are significantly higher than those of the fiber felt products prepared in the comparative examples; wherein: Comparing Example 1 with Comparative Examples 1 to 3, it can be seen that the difference between Example 1 and Comparative Examples 1 to 3 is that Example 1 uses a combination of three PET short fibers with different melting points, Comparative Example 1 uses a combination of high-melting-point and medium-melting-point PET short fibers, Comparative Example 2 uses a combination of high-melting-point and low-melting-point PET short fibers, and Comparative Example 3 uses a combination of medium-melting-point and low-melting-point PET short fibers. The results show that the sound absorption coefficient of the fiber felt product prepared by combining three PET short fibers with different melting points is significantly higher than that of Comparative Examples 1 to 3, especially significantly higher than that of the fiber felt product prepared by combining medium-melting-point and low-melting-point PET short fibers. Comparing Example 1 with Examples 6 to 8 reveals that the difference between Example 1 and Examples 6 to 8 is that Examples 6 to 8 added polyurethane (Covestro 9380A), polyamide (PA6), and polypropyleneimide, respectively, to Example 1. The results show that the sound absorption coefficient of the fiber felt products prepared by adding polyurethane (Covestro 9380A), polyamide, and polypropyleneimide is significantly improved; among them, the sound absorption coefficient of the fiber felt product prepared by adding polyurethane is higher than that prepared by adding polyamide and polypropyleneimide. Comparing Example 1 with Examples 11 and 13, it can be seen that the difference between Examples 11 and 13 and Example 1 is that the heating temperature of the injection fiber process in step (3) and the high temperature steam thermoforming temperature in step (4) are different. The results show that when the heating temperature of the injection fiber process and the high temperature steam thermoforming temperature are too high or too low, the sound absorption coefficient of the prepared fiber felt product will be affected. For example, when the heating temperature of the injection fiber process is 80℃~140℃ and the high temperature steam thermoforming temperature is 160℃~180℃ (Example 1), the sound absorption coefficient of the fiber felt product prepared is significantly higher than that of the fiber felt products prepared in Example 11 (injection fiber process heating temperature is 70℃, high temperature steam thermoforming temperature is 190℃) and Example 13 (injection fiber process heating temperature is 150℃, high temperature steam thermoforming temperature is 150℃).

[0062] 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 special fiber composite material with ultra-high mechanical properties, characterized in that, The special fiber composite material comprises a fiber composition, and the fiber composition comprises: PET short fibers with a melting point of 250-260℃; PET short fibers with a melting point of 160-200℃; PET short fibers with a melting point of 110-130℃; The fineness of the PET short fibers with different melting points is respectively 3D-6D, and the length is respectively 7-25mm.

2. The special fiber composite material according to claim 1, characterized in that, The fiber composition comprises, in terms of mass fraction: PET short fibers with a melting point of 250-260℃: 40-80%; PET short fibers with a melting point of 160-200℃: 10-30%; PET short fibers with a melting point of 110-130℃: 10-30%.

3. The special fiber composite material according to claim 2, characterized in that, The fiber composition comprises, in terms of mass fraction: PET short fibers with a melting point of 250-260℃: 50-70%; PET short fibers with a melting point of 160-200℃: 15-25%; PET short fibers with a melting point of 110-130℃: 15-25%.

4. The specialty fiber composite of claim 2, wherein, The fiber composition comprises, in terms of mass fraction: PET short fibers with a melting point of 260℃: 60%; PET short fibers with a melting point of 180℃: 20%; PET short fibers with a melting point of 110℃: 20%.

5. The specialty fiber composite of claim 2, wherein, The special fiber composite material further comprises polyurethane and / or calcium carbonate.

6. The special fiber composite material according to claim 5, characterized in that In the special fiber composite material, When the special fiber composite material further comprises polyurethane, the mass ratio of the fiber composition to the polyurethane is 1:(0.05-0.1); When the special fiber composite material further comprises calcium carbonate, the mass ratio of the fiber composition to the calcium carbonate is 1:(0.01-0.05); When the special fiber composite material further comprises polyurethane and calcium carbonate, the mass ratio of the fiber composition to the calcium carbonate to the polyurethane is 1:(0.01-0.05):(0.05-0.1).

7. A method of producing a special fiber composite material as claimed in any one of claims 1 to 4, characterized in that, The preparation method comprises: (1) sequentially opening and bulk mixing the fiber composition to obtain mixed fibers; (2) performing injection fiber process on the mixed fibers to obtain preheated mixed fibers; (3) performing high-temperature steam thermoforming treatment on the preheated mixed fibers, and cooling to obtain the special fiber composite material.

8. The method of producing a special fiber composite material according to any one of claims 5 to 6, characterized by, The preparation method comprises: (1) sequentially opening and bulk mixing the fiber composition to obtain mixed fibers; (2) performing injection fiber process on the mixed fibers to obtain preheated mixed fibers; (3) performing high-temperature steam thermoforming treatment on the preheated mixed fibers and the polyurethane and / or calcium carbonate, and cooling to obtain the special fiber composite material.

9. The preparation method according to claim 7 or 8, characterized in that, in step (2), the temperature of the injection fiber process is 70-150℃; and / or in step (3), the temperature of the high-temperature steam thermoforming treatment is 150-190℃.

10. The preparation method according to claim 9, characterized in that, in step (2), the temperature of the injection fiber process is 80-140℃; and / or in step (3), the temperature of the high-temperature steam thermoforming treatment is 160-180℃.

Images