Composite fiber felt, fiber-reinforced polyurethane foam, preparation methods and applications

Abstract

This application relates to a composite fiber felt, fiber-reinforced polyurethane foam material, its preparation method, and its application. The method includes: performing composite spinning to form composite coarse fibers, wherein the composite coarse fibers include at least a first fiber and a second fiber arranged side-by-side and connected, the melting point of the first fiber being lower than that of the second fiber; needle-punching the composite coarse fibers into a web to form a coarse fiber felt; applying a first temperature to the coarse fiber felt to melt the first fiber, and cooling to obtain the composite fiber felt, wherein the first temperature is higher than the melting point of the first fiber and lower than the melting point of the second fiber. This application can solve the problems of low porosity, low bonding strength, and poor polyurethane raw material penetration in related technologies.

Description

Technical Field

[0001] This application relates to the field of fiber materials technology, and in particular to a composite fiber felt, fiber-reinforced polyurethane foam material, preparation method and application. Background Technology

[0002] Vehicle manufacturers have set new requirements for their own carbon emissions, and solutions involve multiple areas such as energy consumption, materials, manufacturing, power, and design. Reducing weight and using recycled and bio-based materials can effectively reduce carbon emissions at the vehicle's usage end. Developing a low-density, recycled, bio-based skid plate material solution is needed by all vehicle manufacturers.

[0003] In some related technologies, high-strength composite panels are made using glass fiber reinforced polyurethane foam. However, glass fiber has poor recyclability, requires pretreatment of its surface, involves complex processes, and has a very high density, which does not meet the lightweight requirements of automotive materials.

[0004] Other related technologies disclose a parallel composite elastic fiber and its manufacturing method. The parallel composite elastic fiber is obtained by parallel composite spinning of polybutylene terephthalate and polyethylene terephthalate in a weight ratio of 70:30 to 30:70, followed by false twisting. When the false-twisted, crimped fibers are made into fiber mats, their high elastic elongation provides almost no reinforcement to polyurethane composite boards when used as polyurethane reinforcing mats.

[0005] Conventional high-density cotton felt has a relatively stable internal structure, but its low porosity prevents polyurethane raw materials from effectively penetrating the material and providing reinforcement. Conventional low-density cotton felt, due to its fewer internal adhesive components, poorer internal structural stability, and shorter fibers, allows polyurethane raw materials to penetrate effectively, but its weaker strength results in a very limited reinforcement effect on polyurethane foam. Summary of the Invention

[0006] This application provides a composite fiber felt, a fiber-reinforced polyurethane foam material, a preparation method, and an application to solve the problems of low porosity, low bonding strength, and poor penetration of polyurethane raw materials in related technologies.

[0007] In a first aspect, a method for preparing a composite fiber felt is provided, comprising:

[0008] Composite spinning is performed to form composite coarse fibers, the composite coarse fibers comprising at least a first fiber and a second fiber arranged side by side and connected, wherein the melting point of the first fiber is lower than the melting point of the second fiber;

[0009] The composite coarse fibers are laid into a web and then needle-punched to form a coarse fiber felt.

[0010] A first temperature is applied to the coarse fiber felt to melt the first fiber, and after cooling, a composite fiber felt is obtained. The first temperature is higher than the melting point of the first fiber and lower than the melting point of the second fiber.

[0011] In some embodiments, the raw material for the first fiber includes one or more of polyethylene (PE) and polypropylene (PP);

[0012] And / or, the raw material for the second fiber includes one or more of polyethylene terephthalate (PET) and PA6;

[0013] And / or, the cross-sectional area ratio of the second fiber to the first fiber is 60-90:10-40;

[0014] And / or, the linear density of the composite coarse fiber is 100D to 200D, and the areal density of the composite coarse fiber after web laying is 300 to 600 g / m². 2 ;

[0015] And / or, the thickness of the coarse fiber felt formed by needle punching is 30 to 50% of the thickness before needle punching after web laying.

[0016] In some embodiments, the preparation method further includes, after melting the first fiber and before cooling:

[0017] Place it into the mold and press it into shape.

[0018] In some embodiments, after cooling, the preparation method further includes:

[0019] The purging is performed at the first purging pressure and the first purging temperature.

[0020] In some embodiments, the first air blowing pressure is 0.2–0.4 MPa;

[0021] And / or, the first air blowing temperature is higher than the melting point of the first fiber and lower than the melting point of the second fiber;

[0022] And / or, the purging time is 30–60 s.

[0023] Secondly, a composite fiber felt is provided, which is prepared by any of the composite fiber felt preparation methods described above.

[0024] Thirdly, a method for preparing a fiber-reinforced polyurethane foam material is provided, comprising:

[0025] The polyurethane foam mixture is injected into the composite fiber felt as described above and foamed to obtain fiber-reinforced polyurethane foam material.

[0026] In some embodiments, the foaming time is 150–300 seconds;

[0027] The density of the polyurethane foam formed by foaming is 50-100 kg / m³. 3 ;

[0028] The polyurethane foam mixture comprises, by weight, 60-70 parts polyether polyol, 25-35 parts polyisocyanate, 2-4 parts silicone oil, 2-3 parts water, and 0.5-2 parts amine catalyst.

[0029] Fourthly, a fiber-reinforced polyurethane foam material is provided, which is prepared by the fiber-reinforced polyurethane foam material preparation method described above.

[0030] Fifthly, the application of the fiber-reinforced polyurethane foam material as described above in automotive fiber-molded parts is provided.

[0031] The beneficial effects of the technical solution provided in this application include:

[0032] This application provides a composite fiber felt, fiber-reinforced polyurethane foam material, preparation method, and application. After preparing the composite coarse fiber, it is needle-punched to form a coarse product. Then, the first fiber is melted to form bonding points. Since the first fiber is connected to the second fiber side-by-side, after the needle-punching process to form the coarse fiber felt, any fiber intersection and any mesh opening in the coarse fiber felt contains the first fiber. During melting, this ensures that the first fiber at any fiber intersection can melt into a bonding point, thereby improving the bonding strength of the fiber felt and enhancing its structural strength and stability. Simultaneously, the melting and aggregation of the first fiber at any mesh opening partially opens up the previously occupied mesh space, increasing porosity and thus improving the permeability of the polyurethane raw material. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 A cross-sectional view of the composite coarse fiber provided in an embodiment of this application;

[0035] Figure 2 A schematic diagram of the internal structure of the fiber felt crude product provided in the embodiments of this application after a first temperature is applied;

[0036] Figure 3 for Figure 2 A schematic diagram of the internal structure after purging;

[0037] Figure 4 This is a schematic diagram of the fiber-reinforced polyurethane foam material provided in the embodiments of this application.

[0038] In the diagram: 1. First fiber; 2. Second fiber; 3. Bonding point. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0040] This application provides a method for preparing a composite fiber felt, which includes the following steps:

[0041] 101: Perform composite spinning to form composite coarse fiber, said composite coarse fiber comprising at least a first fiber and a second fiber arranged side by side and connected, wherein the melting point of the first fiber is lower than the melting point of the second fiber.

[0042] Specifically, after melting the raw materials of the first fiber and the raw materials of the second fiber respectively, the composite coarse fiber is obtained by spinning, drawing, stretching and cooling through a dual-channel spinneret.

[0043] See Figure 1 As shown, the first fiber 1 is used as an auxiliary fiber and the second fiber 2 is used as a main fiber. After being spun, drawn, stretched and cooled by a dual-channel spinneret, the first fiber 1 is arranged side by side and bonded to the second fiber 2, thus forming a composite coarse fiber.

[0044] The raw materials for the first fiber can be of many types. For example, the raw materials for the first fiber include one or more of polyethylene (PE) and polypropylene (PP).

[0045] It is understandable that there are many possible types of raw materials for the second fiber. For example, the raw materials for the second fiber may include one or more of polyethylene terephthalate (PET) and nylon (PA6).

[0046] PET, PA6, PP, and PE can use recycled plastics, with recycled plastics being preferred.

[0047] It is understandable that the aforementioned composite coarse fiber, after being stretched, becomes a long fiber with a certain length, which can be controlled according to actual production needs.

[0048] Similarly, the linear density and areal density of the composite coarse fiber can be controlled according to actual production needs. At the same time, various factors need to be considered. For example, a lower linear density results in finer fibers, which do not provide reinforcement and affect the permeability of the polyurethane liquid material. Conversely, a higher linear density makes the fiber itself too strong, making it difficult to weave into fabric. Therefore, as an example, the linear density of the composite coarse fiber after spinning is 100D to 200D. The areal density also cannot be too high or too low; it needs to be considered from the perspective of the overall density of the formed sheet. Too high a density is not conducive to weight reduction and cost reduction in automotive applications. Therefore, as an example, the areal density of the composite coarse fiber after web laying is 300 to 600 g / m². 2 .

[0049] 102: The composite coarse fiber is laid into a web and then needle-punched to form a coarse fiber felt.

[0050] After the above-mentioned composite coarse fibers are laid into a web, they are pre-consolidated by needle punching. The needle punching density should not be too high, and it is sufficient to needle punch to 30-50% of the original thickness. In other words, the thickness of the fiber felt formed by needle punching is 30-50% of the thickness before needle punching after web laying. If it is too high, it will be easy to spring back when it is formed into thinner parts in the later stage, during hot pressing and hot air blowing.

[0051] 103: Apply a first temperature to the coarse fiber felt to melt the first fiber, and obtain a composite fiber felt after cooling. The first temperature is higher than the melting point of the first fiber and lower than the melting point of the second fiber.

[0052] In step 103, the fiber felt coarse product can be cut according to the product size requirements, and then placed in an oven for heating. The heating temperature is controlled at a first temperature to ensure that only the first fiber with a lower melting point in the composite coarse fiber melts, while the second fiber with a higher melting point remains stable during heating. For example, if the raw material of the first fiber is polyethylene (PE) or polypropylene (PP), and the raw material of the second fiber is polyethylene terephthalate (PET) or nylon (PA6), the first temperature is controlled at 150-200℃, and the baking time is 30-120 seconds. An infrared heating oven is preferred.

[0053] The first fibers, with their lower melting point, will adhere together after melting, forming a relatively stable three-dimensional structure upon cooling. The internal three-dimensional structure is shown in the figure. Figure 2 As shown, Figure 2 In the process, the first fiber 1 melts at least partially to form an adhesive point 3, which is located at the intersection of the intersecting second fibers 2.

[0054] As can be seen, after preparing the composite coarse fiber, this application performs web-laying and needle punching to form a coarse product. Then, the first fiber is melted to form bonding points 3 in the material of the first fiber. Since the first fiber is part that is connected to the second fiber in parallel, after web-laying and needle punching to form the coarse fiber felt, the first fiber is present at any fiber intersection and any mesh opening in the coarse fiber felt. When melting, it can be ensured that the first fiber at any fiber intersection can be melted into bonding points 3, thereby improving the bonding strength of the fiber felt and improving the structural strength and stability of the fiber felt. At the same time, since the first fiber at any mesh opening is melted and aggregated, it will to some extent open up the previously occupied mesh space, thereby increasing the porosity and thus improving the penetration effect of polyurethane raw materials.

[0055] It is understood that in this application, the purpose of applying a first temperature to melt the first fiber is, on the one hand, to form bonding points at the intersection of the composite coarse fibers, and on the other hand, to allow the first fiber at the mesh to leave the mesh space, thereby increasing the size of the mesh and increasing the porosity to facilitate the penetration of polyurethane raw materials.

[0056] Since the first fiber melts and bonds together, the overall proportion of the first fiber should be lower than that of the second fiber, just as... Figure 1 As shown, the first fiber has a relatively smaller cross-sectional area compared to the second fiber.

[0057] As a preferred example, the cross-sectional area ratio of the second fiber to the first fiber is 60-90:10-40, preferably 70-90:10-30.

[0058] Furthermore, in step 103 above, after melting the first fiber and before cooling, the preparation method further includes: placing it in a mold for pre-forming.

[0059] Specifically, when pre-forming by molding in a mold, the first fiber with a low melting point is molded to the required thickness to ensure that it can be smoothly bonded together after melting, forming a strong bond point, thereby ensuring that a relatively stable three-dimensional structure is formed after cooling.

[0060] Furthermore, in step 103 above, after cooling, the preparation method further includes: purging at a first air blowing pressure and a first air blowing temperature.

[0061] The purpose of high-temperature purging is twofold: firstly, it can intensify the aggregation of the low-melting-point first fiber at the fiber cross-section, thereby further improving the fiber structure strength and stability; secondly, it can combine with... Figure 2 and Figure 3As shown, by using high-temperature blowing, the second fibers will also be twisted to a certain extent under the blowing force, thus forming a three-dimensional structure, which further improves the structural strength and stability.

[0062] Furthermore, purging can potentially increase porosity. Specifically, under high-temperature purging, the molten first fiber between two adjacent fiber intersections can be purged as much as possible to the fiber intersection, thus freeing up the space previously occupied by the mesh. This could potentially increase the mesh size, thereby increasing porosity and improving the permeability of the polyurethane raw material. As for the first fiber originally located at the fiber intersection, the presence of the fiber intersection can provide some degree of obstruction, preventing it from being blown away. Ultimately, the molten first fiber will tend to accumulate at the fiber intersection, as... Figure 3 As shown.

[0063] The purging time and the first air purging pressure can be determined according to the actual application requirements. For example, the first air purging pressure is 0.2 to 0.4 MPa and the purging time is 30 to 60 seconds.

[0064] The first air blowing temperature is higher than the melting point of the first fiber and lower than the melting point of the second fiber, ensuring that the first fiber can melt. For example, the air temperature is 150-240°C.

[0065] It is evident that the composite fiber felt prepared using the above-mentioned method possesses excellent structural strength and stability, as well as high porosity, facilitating the penetration of polyurethane raw materials.

[0066] This application also provides a method for preparing a fiber-reinforced polyurethane foam material, comprising: injecting a polyurethane foam mixture into a composite fiber felt, and performing foaming molding to obtain the fiber-reinforced polyurethane foam material. (See also...) Figure 4 As shown, the fiber-reinforced polyurethane foam material includes polyurethane foam 4 and composite fiber felt, with polyurethane foam 4 wrapped around the composite fiber felt.

[0067] Specifically, the composite fiber felt is placed in a polyurethane foam mold and fixed, and liquid polyurethane foam mixture is injected from the nozzle of a high-pressure polyurethane foaming machine, followed by closed-mold foaming and molding.

[0068] By using composite fiber felt for internal reinforcement, the resulting fiber-reinforced polyurethane foam material has advantages such as lightweight, high strength, easy molding, and low carbon emissions, solving the problems of polyurethane foam material being brittle and having low specific strength in thin products.

[0069] The foaming time can be determined according to actual needs. For example, the foaming time is 150 to 300 seconds.

[0070] Regarding polyurethane foam density, considering both total density and stiffness, if the polyurethane foam density is too low, the strength will be too low, while if it is too high, the total density will be too high. To achieve a balance between the two, as a preferred example, the content of the polyurethane foaming mixture is adjusted to achieve a polyurethane foam density of 50-100 kg / m³. 3 .

[0071] The polyurethane foam mixture comprises, by weight, 60-70 parts polyether polyol, 25-35 parts polyisocyanate, 2-4 parts silicone oil, 2-3 parts water, and 0.5-2 parts amine catalyst.

[0072] Semi-rigid or rigid polyurethane foam should be used for foaming.

[0073] Polyether polyols include one or more commonly used materials such as grafted polyether POP and polyol PPG. The hydroxyl value of polyether polyols is 240-480 mgKOH / g.

[0074] Polyisocyanates include commonly used materials such as MDI. The NCO content of polyisocyanates is 25-35%, and the average functionality is 2.5-2.8.

[0075] High-flowability grades of polyether polyols and polyisocyanates are preferred.

[0076] Amine catalysts can be one or more commonly used materials such as Dabco BL-22 and Dabco 33-LV.

[0077] 10-30% bio-based polyether can be added to polyether polyols. The sources of bio-based polyether can be soybean oil ether or castor oil ether.

[0078] It is evident that the fiber-reinforced polyurethane foam material prepared using the above-mentioned method possesses advantages such as lightweight, high strength, easy molding, and low carbon emissions.

[0079] The fiber-reinforced polyurethane foam material prepared in this application can be used in automotive fiber-molded parts.

[0080] The aforementioned automotive fiber-molded parts can be protective panels, wheel covers, etc.

[0081] The present application will be described in detail below through examples and comparative examples.

[0082] Example 1

[0083] Melt spinning: PET is used as the second fiber and PP as the first fiber. After spinning, drawing, stretching, and cooling, a composite coarse fiber is obtained. The linear density of the composite coarse fiber during spinning is 100D, and the cross-sectional area ratio of PET fiber to PP fiber is 60:40. After web laying, the areal density of the composite coarse fiber is 300g / m². 2 After the web is laid and needled, coarse fiber felt is formed.

[0084] Pre-compression molding: The coarse fiber felt is baked in an infrared heating oven at a surface baking temperature of 180℃. After baking, it is placed in a mold for pre-compression molding to a thickness of 5mm.

[0085] High-temperature purging: Under the conditions of air temperature of 200℃ and air pressure of 0.25Mpa, the purging time is 40s to obtain composite fiber felt.

[0086] Injection foaming: Composite fiber felt is placed into a polyurethane foam mold, and liquid polyurethane foam mixture is poured into the mold using a high-pressure foaming machine. The polyurethane foam density is 100 kg / m³. 3 The sample was removed after the closed-mold foam matured for 240 seconds.

[0087] Example 2

[0088] Melt spinning: PET is used as the second fiber and PE as the first fiber. After spinning, drawing, stretching, and cooling, a composite coarse fiber is obtained. The linear density of the composite coarse fiber during spinning is 200D, and the cross-sectional area ratio of PET fiber to PE fiber is 75:25. After web laying, the areal density of the composite coarse fiber is 450g / m². 2 After the web is laid and needled, coarse fiber felt is formed.

[0089] Pre-compression molding: The coarse fiber felt is baked in an infrared heating oven at a surface baking temperature of 160℃. After baking, it is placed in a mold for pre-compression molding to a thickness of 5mm.

[0090] High-temperature purging: Under the conditions of air temperature of 180℃ and air pressure of 0.25Mpa, the purging time is 35s.

[0091] Injection foaming: Composite fiber felt is placed into a polyurethane foam mold, and liquid polyurethane foam mixture is poured into the mold using a high-pressure foaming machine. The polyurethane foam density is 80 kg / m³. 3 The sample was removed after the closed-mold foam had matured for 190 seconds.

[0092] Example 3

[0093] Melt spinning: PA6 is selected as the second fiber and PP as the first fiber. After spinning, drawing, stretching, and cooling, a composite coarse fiber is obtained. The linear density of the composite coarse fiber during spinning is 100D, and the cross-sectional area ratio of PA6 fiber to PP fiber is 80:20. After web laying, the areal density of the composite coarse fiber is 600g / m². 2 After the web is laid and needled, coarse fiber felt is formed.

[0094] Pre-compression molding: The coarse fiber felt is baked in an infrared heating oven at a surface baking temperature of 180℃. After baking, it is placed in a mold for pre-compression molding to a thickness of 5mm.

[0095] High-temperature purging: Under the conditions of air temperature of 200℃ and air pressure of 0.35Mpa, the purging time is 45s.

[0096] Injection foaming: Composite fiber felt is placed into a polyurethane foam mold, and liquid polyurethane foam mixture is poured into the mold using a high-pressure foaming machine. The polyurethane foam density is 55 kg / m³. 3 The sample was removed after the closed-mold foam had matured for 200 seconds.

[0097] Comparative Example 1

[0098] The PP fiberglass board used is a product of Huajiang Technology, with a surface density of 1800g / m². 2 (containing 100g / m 2 Non-woven fabric, after being baked in a 220℃ oven, is molded to 4mm and is commonly used for car shelves.

[0099] The test results are shown in Table 1 below:

[0100] Table 1

[0101] raw material PET+PP PET+PE PA6+PP PP fiberglass board Linear density 100D 200D 300D / areal density <![CDATA[300g / m 2 ]]> <![CDATA[450g / m 2 ]]> <![CDATA[600g / m 2 ]]> / Polyurethane foam density <![CDATA[100kg / m 3 ]]> <![CDATA[50kg / m 3 ]]> <![CDATA[80kg / m 3 ]]> / Sample density <![CDATA[1300g / m 2 ]]> <![CDATA[950g / m 2 ]]> <![CDATA[1400g / m 2 ]]> <![CDATA[1800g / m 2 ]]> Sample thickness 10mm 10mm 10mm 3.5 Bending strength 121N 61N 135N 51N

[0102] It should be noted that the above bending strength was measured using the GB / T 1456-2021 Test Method for Bending Performance of Sandwich Structures.

[0103] Based on the sample densities of Examples 1-3 and Comparative Example 1 in Table 1 above, the density data of each example are much lower than those of the comparative example, even as low as 950 g / m³. 2 It is evident that the fiber-reinforced polyurethane foam material obtained in this application has the advantage of being lightweight.

[0104] From the bending strength of Examples 1-3 and Comparative Example 1 in Table 1 above, the bending strength data of each example is much higher than that of the comparative example, even reaching 135N. It can be seen that the fiber-reinforced polyurethane foam material obtained in this application has the advantage of high strength.

[0105] It is evident that the fiber-reinforced polyurethane foam material provided in this application has advantages such as lightweight, high strength, easy molding, and low carbon emissions, and solves the problems of polyurethane foam material being brittle and having low specific strength in thin products.

[0106] Example 4

[0107] Melt spinning: PET is used as the second fiber and PP as the first fiber. After spinning, drawing, stretching, and cooling, a composite coarse fiber is obtained. The linear density of the composite coarse fiber during spinning is 100D, and the cross-sectional area ratio of PET fiber to PP fiber is 60:40. After web laying, the areal density of the composite coarse fiber is 300g / m². 2 After the web is laid and needled, coarse fiber felt is formed.

[0108] Pre-compression molding: The coarse fiber felt is baked in an infrared heating oven at a surface baking temperature of 180℃. After baking, it is placed in a mold for pre-compression molding to a thickness of 5mm to obtain composite fiber felt.

[0109] Example 5

[0110] Melt spinning: PET is used as the second fiber and PP as the first fiber. After spinning, drawing, stretching, and cooling, a composite coarse fiber is obtained. The linear density of the composite coarse fiber during spinning is 100D, and the cross-sectional area ratio of PET fiber to PP fiber is 60:40. After web laying, the areal density of the composite coarse fiber is 300g / m². 2 After the web is laid and needled, coarse fiber felt is formed.

[0111] Pre-compression molding: The coarse fiber felt is baked in an infrared heating oven at a surface baking temperature of 180℃. After baking, it is placed in a mold for pre-compression molding to a thickness of 5mm.

[0112] High-temperature purging: Under the conditions of air temperature of 200℃ and air pressure of 0.25Mpa, the purging time is 40s to obtain composite fiber felt.

[0113] Comparative Example 2

[0114] The fiber felt is made of rigid fiber felt from Perger Company, with a material weight of 800g / m². 2 It is baked in a 260℃ oven to a thickness of 4mm and used in carpets, front panels and other parts to block the penetration of PU foam. It is made of short fiber, ordinary fiber with a linear density of 1-6.5D.

[0115] Injection foaming: The fiber felt is placed into a polyurethane foam mold, and liquid polyurethane foam mixture is poured into the mold using a high-pressure foaming machine. The polyurethane foam density is 100 kg / m³. 3 The sample was taken out after the closed-mold foam was cured for 240 seconds. It was found that it could only penetrate the surface fiber felt.

[0116] Comparative Example 3

[0117] The fiber felt is PET fiber felt supplied by Chongqing Jinfu, with a basis weight of 400g / m². 2 It is baked in a 260℃ oven to a thickness of 5mm and is commonly used as a sound-absorbing material. It uses short fibers with a linear density of 0.5-2D for sound absorption purposes.

[0118] The test results are shown in Table 2 below:

[0119] Table 2

[0120]

[0121] From the air permeability of Examples 4-5 and Comparative Examples 2-3 in Table 2 above, the air permeability data of each example are much higher than those of the comparative examples. It can be seen that the preparation method provided by this application can improve the air permeability or porosity of the fiber felt, which is beneficial to the penetration of polyurethane foam. When injection foaming was performed in Comparative Example 2, it was found that polyurethane foam could only penetrate the surface fiber felt.

[0122] From the bending strength of Examples 4-5 and Comparative Examples 2-3 in Table 2 above, the bending strength data of each example are much higher than those of the comparative examples, even reaching 121N. It can be seen that the fiber felt prepared by the preparation method provided in this application has good structural strength and stability.

[0123] Based on the bending strength data of Examples 4 and 5, Example 5 has a higher bending strength due to the high-temperature purging process.

[0124] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for producing a composite fiber mat, characterized by, It includes: Composite spinning is performed to form composite coarse fibers, the composite coarse fibers comprising at least a first fiber and a second fiber arranged side by side and connected, wherein the melting point of the first fiber is lower than the melting point of the second fiber; The composite coarse fibers are laid into a web and then needle-punched to form a coarse fiber felt. A first temperature is applied to the crude fiber felt to melt the first fiber. After cooling, it is purged under a first air blowing pressure and a first air blowing temperature to obtain a composite fiber felt. The first temperature is higher than the melting point of the first fiber and lower than the melting point of the second fiber. The first air blowing pressure is 0.2 to 0.4 MPa, the first air blowing temperature is higher than the melting point of the first fiber and lower than the melting point of the second fiber, and the blowing time is 30 to 60 seconds. The cross-sectional area ratio of the second fiber to the first fiber is 60-90:10-40; The linear density of the composite coarse fiber is 100D-200D, and the surface density of the composite coarse fiber after laying is 300-600 g / m 2 ; The thickness of the coarse fiber felt formed by needle punching is 30 to 50% of the thickness before needle punching after web laying.

2. The method for preparing the composite fiber felt as described in claim 1, characterized in that: The raw materials for the first fiber include one or more of polyethylene (PE) and polypropylene (PP); And / or, the raw material for the second fiber includes one or more of polyethylene terephthalate (PET) and PA6.

3. The method for producing a composite fiber mat according to claim 1, wherein After melting the first fiber and before cooling, the preparation method further includes: Place it into the mold and press it into shape.

4. A composite fiber mat characterized by: It is prepared using the method for preparing composite fiber felt as described in any one of claims 1 to 3.

5. A method for producing a fiber-reinforced polyurethane foam material, characterized by, It includes: The polyurethane foam mixture is injected into the composite fiber felt as described in claim 4 and foamed to obtain a fiber-reinforced polyurethane foam material.

6. The method for preparing fiber-reinforced polyurethane foam material as described in claim 5, characterized in that: The foaming time is 150–300 seconds; The polyurethane foam formed by the foaming has a density of 50-100 kg / m 3 ; The polyurethane foam mixture comprises, by weight, 60-70 parts polyether polyol, 25-35 parts polyisocyanate, 2-4 parts silicone oil, 2-3 parts water, and 0.5-2 parts amine catalyst.

7. A fiber-reinforced polyurethane foam, characterized by: It is prepared using the method for preparing fiber-reinforced polyurethane foam as described in claim 5 or 6.

8. The application of the fiber-reinforced polyurethane foam material as described in claim 7 in automotive fiber-molded parts.

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