A method for manufacturing a large-tow carbon fiber composite material by a substitute yarn spreading process

Abstract

The application discloses a method for preparing large-tow carbon fiber composite material by replacing a yarn spreading process, and comprises the following steps: taking large-tow carbon fiber as core yarn and organic fiber bundle as outer wrapping yarn, performing wrapping on a wrapping machine to obtain large-tow carbon fiber wrapping yarn; wherein the specification of the core yarn is 36K or above large-tow carbon fiber; the linear density of the outer wrapping yarn is 100dtex-400dtex; the mass ratio of the outer wrapping yarn to the large-tow carbon fiber is 0.1-0.6:1; after the large-tow carbon fiber wrapping yarn or fabric is woven, the large-tow carbon fiber wrapping yarn or fabric is subjected to surface treatment and is compounded with thermoplastic resin and / or thermosetting resin to obtain large-tow carbon fiber composite material. The flexible organic fiber is wrapped outside the large-tow carbon fiber by using a wrapping method to prepare wrapping yarn, and therefore, prepreg and composite material can be prepared without a yarn spreading process, and the prepared composite material is stable in performance and excellent in comprehensive performance.

Description

Technical Field

[0001] This invention relates to the field of large-tow carbon fiber composite materials, and in particular to a method for preparing large-tow carbon fiber composite materials that replaces the yarn spreading process. Background Technology

[0002] Carbon fiber is a fibrous carbon material with a molecular structure between graphite and diamond. The carbon content in the fiber is generally above 90%, and it possesses excellent mechanical and electrical properties, corrosion resistance, high-temperature resistance, and a low coefficient of thermal expansion, among other superior properties. The term "carbon fiber" usually refers not to a single carbon fiber filament, but rather to a bundle of thousands of filaments. Based on the number of filaments in the bundle, carbon fiber bundles can be divided into aerospace-grade small bundles and industrial-grade large bundles. Generally, carbon fiber bundles with less than 36K filaments (i.e., fewer than 36,000 filaments) are called small-bundle carbon fiber, such as 1K, 3K, 12K, and 24K; while carbon fiber bundles with 36K filaments and above are called large-bundle carbon fiber, including 36K, 48K, 50K, and 60K.

[0003] Compared to small-tow carbon fiber, large-tow carbon fiber has a greater cost advantage and is expected to be used in more applications. However, the number of holes on the spinneret increases significantly when preparing large-tow carbon fiber. This requires ensuring that all the monofilaments ejected from the spinneret holes have the same uniformity and sizing rate, thus increasing the difficulty exponentially. Inevitably, the prepared carbon fiber will exhibit problems such as fuzzing, broken fibers, uneven fiber thickness distribution, twisting, buckling, and fiber separation during use or processing.

[0004] Currently, the common practice both domestically and internationally is to use a yarn-spreading process to unfold large-tow carbon fibers, making them exhibit a relatively uniform thickness in a ribbon-like thin-layer structure. This addresses the issue of uneven thickness distribution in large-tow carbon fibers and is beneficial for subsequent composite material preparation. However, during the yarn-spreading process, phenomena such as wear, fuzzing, yarn disorder, yarn breakage, and fiber separation in the large-tow carbon fibers remain significant, affecting the performance of the prepared composite materials (including prepregs).

[0005] Therefore, it is necessary to design an alternative yarn-spreading process for large-tow carbon fibers to solve the problems of wear, fuzz, yarn disorder, yarn breakage and fiber separation that occur during the current yarn-spreading or use of large-tow carbon fibers, so as to obtain better performance of the prepared composite materials. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by proposing an alternative method for preparing large-tow carbon fiber composite materials using a yarn-spreading process.

[0007] A method for preparing large-tow carbon fiber composites using an alternative to the yarn spreading process includes the following steps:

[0008] S1. Using large-tow carbon fiber as the core yarn and organic fiber bundles as the outer yarn, the yarn is coated on a coating machine to obtain large-tow carbon fiber coated yarn.

[0009] The core yarn is made of 36K or higher large-tow carbon fiber.

[0010] The outer covering yarn is an organic fiber with a linear density of 100dtex-400dtex, wherein the outer covering yarn is a single yarn or multiple yarns after being doubly spun;

[0011] The mass ratio of the outer covering yarn to the large tow carbon fiber is 0.1-0.6:1;

[0012] S2. The surface of the large-tow carbon fiber coating yarn is treated and cured with thermoplastic resin / or thermosetting resin to obtain a large-tow carbon fiber composite material.

[0013] Preferably, the method further includes: weaving or braiding the large-tow carbon fiber coated yarn in S1 on a loom to obtain a large-tow carbon fiber coated yarn fabric; then surface-treating the large-tow carbon fiber coated yarn fabric and compounding it with a thermoplastic resin and / or a thermosetting resin to obtain a large-tow carbon fiber composite material.

[0014] Preferably, in S1, the organic fiber is at least one of polyester fiber, nylon fiber, and aramid fiber after alkali reduction.

[0015] Preferably, during the surface treatment of S2, the surface is impregnated with an aqueous epoxy emulsion with a solid content of 1%; and dried at a temperature of 105-120°C under infrared conditions.

[0016] As an alternative, sol-gel nano-hybrid materials can be constructed, in which the organic phase is the same as or similar to the matrix, the inorganic phase is silicon dioxide, titanium dioxide, aluminum oxide, etc., and 0.1% fluorocarbon is added.

[0017] Preferably, the wrapping degree is calculated according to the mass ratio of the outer yarn to the core yarn of 0.1-0.6:1, and the core yarn is wrapped after the wrapping degree is set on the wrapping machine.

[0018] The wrapping degree ranges from 600*2 to 2000*2. The linear density of the wrapped yarn is calculated using the following formula: Alternatively, the formula can be modified to calculate the wrapping degree based on the linear density.

[0019]

[0020] In the formula: ρ b denoted as linear density of carbon fiber coated yarn, in tex;

[0021] ρ cdenoted as linear density of large-tow carbon fibers, in tex;

[0022] ρ w The linear density of the outer covering yarn fiber is expressed in tex.

[0023] d c The diameter of the large-tow carbon fiber is in μm;

[0024] d s The diameter of the outer covering yarn fiber, in μm;

[0025] T represents the degree of wrapping, T / m;

[0026] n is the number of outer yarn threads.

[0027] Preferably, in S3, the thermoplastic resin is at least one of polyamide, polycarbonate, and polyetheretherketone.

[0028] Preferably, in S2, the thermosetting resin is at least one of epoxy resin, phenolic resin, and polyimide.

[0029] The technical effects of this invention are as follows:

[0030] This invention proposes an alternative process for large-tow carbon fiber, which involves coating the large-tow carbon fiber with an outer layer of organic fiber bundles and then curing it with thermoplastic resin / or thermosetting resin. This effectively solves the problems of fiber separation, wear, yarn disorder, yarn breakage, and weaving damage in large-tow carbon fiber, thereby effectively improving the performance of large-tow carbon fiber composite materials.

[0031] Furthermore, the wrapping process introduces numerous pits onto the carbon fiber surface, and the surfaces of nylon fibers and alkali-reduced polyester fibers contain a large number of active functional groups such as hydroxyl, carbonyl, and carboxyl groups. This allows thermosetting resins like epoxy resins to form a strong interfacial bond through chemical bonds during the curing reaction. When combined with large-tow carbon fibers, this effectively transfers loads and bears the load under external forces. The resulting product not only has high tensile strength but also low strength unevenness and excellent mechanical properties. Similarly, when combined with thermoplastic resins such as polyamide, the thermoplastic resins exhibit good wettability with organic fibers due to the principle of similarity affinity.

[0032] This invention utilizes a wrapping method to coat flexible organic fibers onto the outside of large tow carbon fibers to prepare coated yarn, directly producing fabrics and composite materials (including prepregs) without the need for a yarn unfolding process. The matrix of the composite material can be a thermosetting matrix or a thermoplastic matrix, and the prepared composite material exhibits stable properties and excellent overall performance. Attached Figure Description

[0033] Figure 1This is the apparatus for preparing the large-tow carbon fiber composite material of the present invention (a modification of a commercial machine).

[0034] Among them: 1. Feeding roller; 2. Carbon fiber filament tube; 3. Drafting roller; 4. Guide roller; 5. Belt; 6. Hollow spindle; 7. Covered yarn tube; 8. Yarn pressing device; 9. Yarn guiding roller; 10. Pressure roller; 11. Reciprocating yarn guide; 12. Take-up roller; 13. Carbon fiber wrapped yarn collecting roller. Detailed Implementation

[0035] The present invention will be further explained below with reference to specific embodiments.

[0036] like Figure 1 The image shows the apparatus for preparing the large-tow carbon fiber composite material described in Examples 1-5 (modified from a commercial machine).

[0037] Example 1

[0038] A method for preparing large-tow carbon fiber composite materials using an alternative to the yarn spreading process, characterized by comprising the following steps:

[0039] S1. Use 72 dtex nylon yarn (density 1.15 g / cm³). 3 Two nylon fibers (melting point 260℃) are spun together on a spinning machine to form a nylon yarn with a linear density of 144 dtex. 48K large-tow carbon fiber is used as the core yarn, and the 144 dtex nylon yarn is used as the outer wrapping yarn. The yarn is then wrapped a second time on a wrapping machine. The wrapping degree is calculated based on a mass ratio of 0.4:1 between the outer wrapping yarn and the large-tow carbon fiber. After setting the wrapping degree on the wrapping machine, the large-tow carbon fiber is wrapped to obtain a large-tow carbon fiber coated yarn.

[0040] The large tow carbon fiber is model Dongbang STS40-48K, with 48K fibers and a fiber diameter of 7.0μm.

[0041] S2. After impregnating the wrapped large-tow carbon fiber in epoxy resin containing curing agent, it is compressed and hot-pressed at a temperature of 150°C, controlling the carbon fiber mass content to be 15%, and then cooled to obtain a thermosetting composite material reinforced with large-tow carbon fiber.

[0042] The prepared composite material was subjected to tensile testing. The fracture strength of the composite material was 675 MPa, and the strength non-uniformity was 7.5%.

[0043] For comparison, carbon fibers of the same type and specification were spread on a spinning machine. After spreading, the fibers were impregnated in epoxy resin containing a curing agent and then compressed and hot-pressed at 150°C. The carbon fiber content was controlled to prepare a composite material with a carbon fiber content of 15%. After cooling, a control sample composite material was obtained, which is Comparative Example 1. Tensile tests were conducted, and the tensile strength of the composite material was 603 MPa, with a strength unevenness of 11.3%.

[0044] The tensile strength test method described above is based on ISO 527-4:1997 standard. The Instron 3367 universal testing machine was used to conduct tensile tests on carbon fiber wrapped yarn composite materials at room temperature of 25°C. The sample size was 100mm×10mm×4mm, the gauge length was 50mm, the tensile rate was 2mm / min, and the effective sample capacity for each group was 5 samples.

[0045] Example 2

[0046] A method for preparing large-tow carbon fiber composite materials using an alternative to the yarn spreading process, characterized by comprising the following steps:

[0047] S1. Preparation of large-tow carbon fiber coated yarn: 100 dtex nylon fiber (density 1.14 g / cm³) was selected. 3 The outer yarn (melting point 220℃) is used as the outer yarn, and the core yarn is 48K large-tow carbon fiber. The yarn is then wrapped a second time on a wrapping machine. The wrapping degree is calculated based on a mass ratio of 0.2:1 between the outer yarn and the large-tow carbon fiber. After setting the wrapping degree on the wrapping machine, the carbon fiber is wrapped to obtain a large-tow carbon fiber coated yarn. The specific calculation of the wrapping degree is detailed in Example 1.

[0048] The large tow carbon fiber is model Dongbang STS40-48K, with 48K fibers and a fiber diameter of 7.0μm.

[0049] S2. The wrapped carbon fiber bundles are woven into plain weave fabric on a loom. The polyamide film and the fabric are then composited at 235°C using a hot pressing process to prepare a composite material with a carbon fiber content of 15%.

[0050] In the tensile test, the radial fracture strength of the composite material was 363 MPa, and the strength non-uniformity was 4.7%.

[0051] For comparison, carbon fibers of the same type and specification were spread on a spinning machine, and the spread carbon fibers were then woven into a plain weave on a loom. The polyamide film was then composited with the fabric at a temperature of 235°C using a hot pressing process to prepare a composite material with a carbon fiber content of 15%, which is Comparative Example 2. Tensile tests were conducted, and the radial breaking strength of the composite material was 305 MPa, with a strength unevenness rate of 9.6%.

[0052] Example 3

[0053] A method for preparing large-tow carbon fiber composite materials using an alternative to the yarn spreading process, characterized by comprising the following steps:

[0054] S1. Aramid fibers with a linear density of 100 dtex (density 1.35 g / cm³) are selected. 3 Two aramid fibers (melting point 260℃) are spun together on a spinning machine to form nylon yarn with a linear density of 200 dtex. 48K large-tow carbon fiber is used as the core yarn, and 400 dtex nylon yarn is used as the outer wrapping yarn. The yarn is then wrapped a second time on a wrapping machine. The wrapping degree is calculated based on a mass ratio of 0.6:1 between the outer wrapping yarn and the large-tow carbon fiber. After setting the wrapping degree on the wrapping machine, the large-tow carbon fiber is wrapped to obtain a large-tow carbon fiber coated yarn.

[0055] The 36K large-tow carbon fiber is designated as Toray 36K, with 36K fibers and a fiber diameter of 6.5μm.

[0056] After the large tow carbon fibers were wrapped, they were impregnated and dried in water-based epoxy resin with a solid content of 1%, and then impregnated in epoxy resin (containing curing agent). After compression molding, they were cured at 75℃ for 2 hours, and then cured at 115℃ for 20 minutes. The mass content of carbon fibers was controlled at 15%. After cooling, the large tow carbon fiber composite material was obtained.

[0057] The prepared composite material was subjected to tensile testing. The fracture strength of the composite material was 829 MPa, and the strength non-uniformity was 2.5%.

[0058] Example 4

[0059] A method for preparing large-tow carbon fiber composite materials using an alternative to the yarn spreading process, characterized by comprising the following steps:

[0060] S1. 200 dtex polyester fiber (density 1.38 g / cm³) is selected. 3Two polyester fibers (melting point 260℃) are spun together on a spinning machine to form a polyester yarn with a linear density of 400 dtex. 48K large-tow carbon fiber is used as the core yarn, and the 400 dtex polyester yarn is used as the outer wrapping yarn. The yarn is then wrapped a second time on a wrapping machine. The wrapping degree is calculated based on a mass ratio of 0.1:1 between the outer wrapping yarn and the large-tow carbon fiber. After setting the wrapping degree on the wrapping machine, the large-tow carbon fiber is wrapped to obtain a large-tow carbon fiber coated yarn.

[0061] The large tow carbon fiber is model Dongbang STS40-48K, with 48K fibers and a fiber diameter of 7.0μm.

[0062] After the surface of the wrapped large tow carbon fiber is treated, it is impregnated in epoxy resin to become a pre-impregnated tape. Then, it is compressed and cured at 75℃ for 2 hours, then the temperature is increased to 115℃ for 20 minutes, and the carbon fiber mass content is controlled at 15%. After cooling, the large tow carbon fiber composite material is obtained.

[0063] The prepared composite material was subjected to tensile testing. The fracture strength of the composite material was 683 MPa, and the strength non-uniformity was 7.4%.

[0064] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing large-tow carbon fiber composite materials as an alternative to the yarn spreading process, characterized in that, Includes the following steps: S1. Using large-tow carbon fiber as the core yarn and organic fiber bundles as the outer yarn, the yarn is coated on a coating machine to obtain large-tow carbon fiber coated yarn. The core yarn is made of 36K or higher large-tow carbon fiber. The outer covering yarn is an organic fiber with a linear density of 100 dtex-400 dtex; The mass ratio of the outer covering yarn to the large tow carbon fiber is 0.1-0.6:1; S2. Surface treatment of the large-tow carbon fiber coated yarn, and composite with thermoplastic resin and / or thermosetting resin to obtain large-tow carbon fiber composite material. The organic fiber is at least one of polyester fiber, nylon fiber, and aramid fiber after alkali reduction. The wrapping degree is calculated based on a mass ratio of 0.1-0.6:1 between the outer yarn and the core yarn. After setting the wrapping degree on the wrapping machine, the core yarn is wrapped. A two-stage wrapping method is used, with the wrapping degree ranging from 600*2 to 2000*2. The linear density of the carbon fiber coated yarn is calculated using the following formula: In the formula: ρ b denoted as linear density, in tex; ρ c denoted as linear density of large-tow carbon fiber, in tex; ρ w The linear density of the outer covering yarn fiber is expressed in tex. d c The diameter of the large-tow carbon fiber is in µm; d s The diameter of the outer covering yarn fiber, in µm; T The degree of wrapping is expressed in T / m. n is the number of outer yarn threads.

2. The method for preparing large-tow carbon fiber composite materials according to claim 1, wherein the alternative yarn-spreading process is characterized in that, Also includes: The large-tow carbon fiber coated yarn in S1 is woven or braided on a loom to obtain a large-tow carbon fiber coated yarn fabric. Then, the surface of the large-tow carbon fiber coated yarn fabric is treated and compounded with thermoplastic resin and / or thermosetting resin to obtain a large-tow carbon fiber composite material.

3. The method for preparing large-tow carbon fiber composite materials according to claim 1 or 2, wherein the alternative yarn-spreading process is characterized in that, During the surface treatment of S2, it is impregnated with an aqueous epoxy emulsion with a solid content of 1%; and dried at a temperature of 105-120℃ under infrared conditions.

4. The method for preparing large-tow carbon fiber composite materials according to claim 1, wherein... In S2, the thermoplastic resin is at least one of polyamide resin, polycarbonate, and polyetheretherketone.

5. The method for preparing large-tow carbon fiber composite materials according to claim 1, wherein... In S2, the thermosetting resin is at least one of epoxy resin, phenolic resin, and polyimide.

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