Covalent organic framework and polyamide 6 composite fiber and preparation method thereof

Abstract

The invention relates to the technical field of high polymer materials, in particular to a covalent organic framework and polyamide 6 composite fiber and a preparation method thereof. The preparation method of the covalent organic framework and polyamide 6 composite fiber comprises the following steps that covalent organic framework powder and polyamide 6 powder are mixed and then added into a ball milling tank, then ball milling treatment is conducted through a ball mill, and a spinning raw material is obtained; sequentially carrying out drying treatment and spinning treatment on the spinning raw material to obtain nascent fibers; and drafting the nascent fiber to obtain the covalent organic framework and polyamide 6 composite fiber. According to the preparation method, the covalent organic framework and polyamide 6 composite fiber with excellent tensile strength and toughness can be prepared. The preparation method is simple in process, easy to operate and suitable for large-scale production.

Description

Technical Field

[0001] The invention relates to the technical field of polymer materials, and in particular to a covalent organic framework and polyamide 6 composite fiber and a preparation method thereof. Background Art

[0002] Polyamide 6 (PA6), also known as nylon 6, contains repeated amide groups (-CONH-) in its main chain structure, which can form hydrogen bonds between molecules and is an important synthetic polymer material. Due to its excellent mechanical properties, wear resistance, and easy processing and molding, polyamide 6 is widely used in the preparation of fibers, engineering plastics, and films. Among them, polyamide 6 fiber, as an important type of polyamide product, has a wide range of applications in transportation, aerospace, national defense science and technology, medical protection, and electronic communications due to its heat resistance, oxidation resistance, and easy processing. However, traditional polyamide 6 fibers have the problem of low tensile strength, which limits their application. Therefore, it is urgent to explore polyamide 6 fibers with excellent tensile strength.

[0003] The Chinese patent technology with publication number CN 108486678 A discloses a method for preparing a graphene / polyamide 6 composite fiber, wherein a graphene / polyamide 6 composite material is obtained by in-situ polymerization, formic acid is added to dissolve the obtained composite material to form a solution, and then a graphene / polyamide 6 composite fiber is prepared by wet spinning. The graphene / polyamide 6 composite fiber has a high tensile strength. However, the in-situ polymerization process in the invention is complicated, the production cost is high, and it is difficult to achieve large-scale production.

[0004] Therefore, exploring a simple process and obtaining polyamide 6 fiber with excellent tensile strength is a technical problem that needs to be urgently solved in this field. Summary of the invention

[0005] The present invention provides a method for preparing a covalent organic framework and polyamide 6 composite fiber. The method comprises compounding the covalent organic framework with polyamide 6 to prepare the covalent organic framework and polyamide 6 composite fiber having excellent tensile strength and toughness. The method has a simple process, is easy to operate, and is suitable for large-scale production.

[0006] The present invention also provides a covalent organic framework and polyamide 6 composite fiber, which is prepared by the above preparation method, so the covalent organic framework and polyamide 6 composite fiber has excellent tensile strength and toughness.

[0007] A first aspect of the present invention provides a method for preparing a covalent organic framework and polyamide 6 composite fiber, comprising the following steps:

[0008] The covalent organic framework powder and the polyamide 6 powder are mixed and added into a ball milling tank, and then ball milled by a ball mill to obtain a spinning raw material;

[0009] The spinning raw material is sequentially dried and spun to obtain primary fibers;

[0010] The as-spun fibers are subjected to a drafting process to obtain the covalent organic framework and polyamide 6 composite fibers.

[0011] The method for preparing the covalent organic framework and polyamide 6 composite fiber as described above, wherein the covalent organic framework comprises TpPa-COF, and the structural formula of the TpPa-COF is as follows:

[0012]

[0013] In the method for preparing the covalent organic framework and polyamide 6 composite fiber as described above, in the spinning raw material, the mass ratio of the TpPa-COF powder to the polyamide 6 powder is (0.03-0.2):10.

[0014] In the method for preparing the covalent organic framework and polyamide 6 composite fiber as described above, in the spinning raw material, the mass ratio of the TpPa-COF powder to the polyamide 6 powder is (0.05-0.1):10.

[0015] The method for preparing the covalent organic framework and polyamide 6 composite fiber as described above comprises mixing the covalent organic framework powder and the polyamide 6 powder and adding them into a ball milling jar, and then performing ball milling treatment by a ball mill, comprising:

[0016] The covalent organic framework powder and the polyamide 6 powder are mixed and added into a ball mill jar, and ball mill beads are added, and then the mixture is ball milled at a speed of 500 rpm to 700 rpm for 1 h to 3 h.

[0017] In the method for preparing the covalent organic framework and polyamide 6 composite fiber as described above, the drying treatment is performed at a temperature of 80° C. to 100° C. and for a time of 18 h to 24 h.

[0018] In the method for preparing the covalent organic framework and polyamide 6 composite fiber as described above, the spinning treatment temperature is 230°C to 240°C.

[0019] The method for preparing the covalent organic framework and polyamide 6 composite fiber as described above, wherein the spun fiber is subjected to a drafting treatment, comprises:

[0020] The as-spun fibers are stretched by a hot roller at 100° C. to 140° C.

[0021] The second aspect of the present invention provides a covalent organic framework and polyamide 6 composite fiber, which is prepared by the preparation method of the covalent organic framework and polyamide 6 composite fiber.

[0022] Compared with the prior art, the solution of the present invention has at least the following effects:

[0023] The invention provides a method for preparing a covalent organic framework and polyamide 6 composite fiber, wherein the covalent organic framework (COFs) is composited with polyamide 6 (PA6) to prepare a covalent organic framework and polyamide 6 composite fiber having excellent tensile strength and toughness. The preparation method is simple in process, easy to operate, and suitable for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 is the structural formula of TpPa-COF of the present invention;

[0026] Figure 2 is the structural formula of AM-COF of the present invention;

[0027] Figure 3 This is a SEM image of the covalent organic framework and polyamide 6 composite fiber in Example 3 of the present invention;

[0028] Figure 4 This is the SEM image of the polyamide 6 fiber in Comparative Example 6 of the present invention. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] If no specific techniques or conditions are specified in the examples of the present invention, the techniques or conditions described in the literature in the field or the product instructions are used. If no manufacturer is specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0031] It should be noted that the descriptions involving “first”, “second”, etc. in the present invention are used to distinguish similar objects, but are not used to describe a specific order or sequence, and therefore cannot be understood as a limitation of the present invention.

[0032] The term "covalent organic framework" refers to a new type of organic framework porous material with a porous structure. Its structure is mainly composed of light elements such as carbon, oxygen, and hydrogen. It has outstanding characteristics such as controllable structure, adjustable pores, high chemical stability, large specific surface area, and low density. NH bonds, O, and benzene rings exist in the covalent organic framework structure.

[0033] A first aspect of the present invention provides a method for preparing a covalent organic framework and polyamide 6 composite fiber, comprising the following steps:

[0034] The covalent organic framework powder and the polyamide 6 powder are mixed and added into a ball milling tank, and then ball milled by a ball mill to obtain a spinning raw material;

[0035] The spinning raw materials are sequentially dried and spun to obtain primary fibers;

[0036] The covalent organic framework and polyamide 6 composite fibers are obtained by drawing the raw fibers.

[0037] The present invention does not particularly limit the specific sources of the above-mentioned raw materials, which can be purchased from commercial channels or prepared according to methods well known to those skilled in the art.

[0038] The object prepared by the present invention is a covalent organic framework and polyamide 6 composite fiber. Specifically, the covalent organic framework powder and the polyamide 6 powder are first mixed to obtain a mixture, the mixture is added to a ball mill, and then ball milled by a ball mill to obtain a spinning raw material. The ball milling treatment is to make the covalent organic framework powder and the polyamide 6 powder more evenly mixed so that the two materials can interact with each other better; the spinning raw material is dried to obtain a dried spinning raw material. The drying treatment is to remove moisture or solvent that may exist in the spinning raw material to prevent the influence of moisture or solvent in the subsequent spinning treatment process, thereby causing uneven fiber formation; the dried spinning raw material is spun to obtain a nascent fiber. The spinning treatment is to convert the dried spinning raw material into a substance with a fiber form; the nascent fiber is stretched to make the molecular chains of the nascent fiber be oriented to obtain a covalent organic framework and polyamide 6 composite fiber with excellent tensile strength and toughness. The inventors analyzed this and believed that the reasons are: (1) by adding a covalent organic framework, the condensed state of the polyamide 6 molecular chain is improved, and the defects between polyamide 6 molecules are reduced, thereby improving the tensile strength and toughness of the fiber; (2) there are NH bonds, O and benzene rings in the covalent organic framework structure, and its NH bonds and O can form a large number of hydrogen bonds with the polyamide 6 molecular chains, and the intermolecular interaction force is strong, thereby improving the tensile strength and toughness of the fiber; (3) the covalent organic framework is a material with a porous structure, and the polyamide 6 molecular chain is a linear structure and contains a large number of amide bonds (-CONH-). The porous structure of the covalent organic framework can be used to make the covalent organic framework play a clamping role, effectively embedding the polyamide 6 molecular chain into the surface to form a nano-confinement effect, so that it can enhance the interaction between the polyamide 6 molecular chains and improve the tensile strength and toughness of the fiber.

[0039] The preparation method of the covalent organic framework and polyamide 6 composite fiber provided by the invention has simple process, is easy to operate, and is suitable for large-scale production.

[0040] In a specific embodiment, the covalent organic framework comprises TpPa-COF, and the structural formula of TpPa-COF is as shown in formula (1):

[0041]

[0042] When the covalent organic framework used is TpPa-COF, TpPa-COF can be composited with polyamide 6 to prepare a covalent organic framework and polyamide 6 composite fiber having excellent tensile strength and toughness.

[0043] In a specific embodiment, in the above spinning raw material, the mass ratio of TpPa-COF powder to polyamide 6 powder is (0.03-0.2):10.

[0044] When the mass ratio of TpPa-COF powder to polyamide 6 powder in the spinning raw material is within the above range, a covalent organic framework and polyamide 6 composite fiber with excellent mechanical properties can be prepared.

[0045] Illustratively, in the above spinning raw materials, the mass ratio of TpPa-COF powder to polyamide 6 powder can be any one of 0.03:10, 0.04:10, 0.05:10, 0.06:10, 0.07:10, 0.08:10, 0.09:10, 0.1:10, 0.2:10 or any two of them.

[0046] In a specific embodiment, in the above spinning raw material, the mass ratio of TpPa-COF to polyamide 6 powder is (0.05-0.1):10.

[0047] When the mass ratio of TpPa-COF powder to polyamide 6 powder in the spinning raw material is within the above range, a covalent organic framework and polyamide 6 composite fiber having excellent tensile strength and toughness can be prepared.

[0048] Illustratively, in the above spinning raw materials, the mass ratio of TpPa-COF powder to polyamide 6 powder may be in the range of any one of 0.05:10, 0.06:10, 0.07:10, 0.08:10, 0.09:10, 0.1:10, or any two of them.

[0049] In a specific embodiment, the covalent organic framework powder and the polyamide 6 powder are mixed and added into a ball milling jar, and then ball milled by a ball mill, comprising:

[0050] The covalent organic framework powder and the polyamide 6 powder are mixed and added into a ball mill jar, and ball mill beads are added, and then the mixture is ball milled at a speed of 500 rpm to 700 rpm for 1 h to 3 h.

[0051] The present invention ball-mills the mixture of the covalent organic framework powder and the polyamide 6 powder through the above process, so that the covalent organic framework powder and the polyamide 6 powder can be mixed more evenly, and the two materials can interact with each other better, which is conducive to the subsequent preparation of the covalent organic framework and polyamide 6 composite fiber with excellent tensile strength and toughness.

[0052] In a specific embodiment, the drying process is carried out at a temperature of 80°C to 100°C and for a time of 18h to 24h.

[0053] When the temperature and time parameters of the drying treatment are respectively within the above ranges, water or solvent that may be present in the spinning raw material can be effectively removed.

[0054] In a specific embodiment, the spinning process is carried out at a temperature of 230°C to 240°C.

[0055] When the temperature parameters of the above-mentioned spinning process are within the above-mentioned range, the spinning raw materials can be effectively melted and have good fluidity, so that the covalent organic framework and polyamide 6 in the spinning raw materials can better form a composite structure during the spinning process, and promote the interaction between the covalent organic framework and polyamide 6, which is beneficial to the subsequent preparation of covalent organic framework and polyamide 6 composite fibers with excellent tensile strength and toughness.

[0056] In one specific embodiment, the as-spun fibers are subjected to a drafting process, comprising:

[0057] The spun fibers are stretched by a hot roller at 100°C to 140°C.

[0058] When the spun fibers are stretched by a hot roller at 100°C to 140°C, the molecular chains of the spun fibers can be arranged more orderly, which is beneficial for obtaining a covalent organic framework and polyamide 6 composite fiber with excellent tensile strength and toughness.

[0059] The second aspect of the present invention provides a covalent organic framework and polyamide 6 composite fiber, which is prepared by the above-mentioned method for preparing the covalent organic framework and polyamide 6 composite fiber. Therefore, the covalent organic framework and polyamide 6 composite fiber has excellent tensile strength and toughness.

[0060] The present invention is described in detail by the following examples and comparative examples.

[0061] Example 1

[0062] The method for preparing the covalent organic framework and polyamide 6 composite fiber provided in this embodiment comprises the following steps:

[0063] 30 mg TpPa-COF (structural formula: Figure 1 As shown) was added to the first zirconia ball mill at room temperature and 40 g of the first zirconia ball mill beads were added, and then ball milled at a rate of 600 rpm for 2 h by a ball mill to obtain a uniform TpPaCOF powder;

[0064] After mixing uniform TpPaCOF powder and 10 g of polyamide 6 powder to obtain a mixture, the mixture was added to a second zirconia ball milling jar and 40 g of second zirconia ball milling beads were added, and then ball milled at a rate of 600 rpm for 2 h by a ball mill to obtain a uniform spinning raw material;

[0065] The uniform spinning raw material is placed in a vacuum oven at a temperature of 100° C. for drying for 24 hours to obtain a dried spinning raw material;

[0066] The dried spinning raw material is subjected to spinning treatment at 235° C. by a melt spinning method to obtain a primary fiber;

[0067] The as-spun fibers were drawn by a hot roller at 140° C. to obtain covalent organic framework and polyamide 6 composite fibers.

[0068] Example 2

[0069] The preparation method of the covalent organic framework and polyamide 6 composite fiber provided in this embodiment is consistent with that in Example 1, except that:

[0070] 30 mg TpPa-COF was replaced with 50 mg TpPa-COF.

[0071] Example 3

[0072] The preparation method of the covalent organic framework and polyamide 6 composite fiber provided in this embodiment is consistent with that in Example 1, except that:

[0073] 30 mg TpPa-COF was replaced with 100 mg TpPa-COF.

[0074] Example 4

[0075] The preparation method of the covalent organic framework and polyamide 6 composite fiber provided in this embodiment is consistent with that in Example 1, except that:

[0076] 30 mg TpPa-COF was replaced with 200 mg TpPa-COF.

[0077] Comparative Example 1

[0078] The preparation method of the covalent organic framework and polyamide 6 composite fiber provided in this comparative example is consistent with that in Example 1, except that:

[0079] 30 mg TpPa-COF was replaced with 10 mg TpPa-COF.

[0080] Comparative Example 2

[0081] The preparation method of the covalent organic framework and polyamide 6 composite fiber provided in this comparative example is consistent with that in Example 1, except that:

[0082] 30 mg TpPa-COF was replaced with 30 mg AM-COF (structural formula: Figure 2 shown).

[0083] Comparative Example 3

[0084] The preparation method of the covalent organic framework and polyamide 6 composite fiber provided in this comparative example is consistent with that in Example 1, except that:

[0085] 30 mg TpPa-COF was replaced by 50 mg AM-COF.

[0086] Comparative Example 4

[0087] The preparation method of the covalent organic framework and polyamide 6 composite fiber provided in this comparative example is consistent with that in Example 1, except that:

[0088] 30 mg TpPa-COF was replaced with 100 mg AM-COF.

[0089] Comparative Example 5

[0090] The preparation method of the covalent organic framework and polyamide 6 composite fiber provided in this comparative example is consistent with that in Example 1, except that:

[0091] 30 mg TpPa-COF was replaced by 200 mg AM-COF.

[0092] Comparative Example 6 (without adding TpPa-COF)

[0093] The preparation method of polyamide 6 fiber provided in this comparative example comprises the following steps:

[0094] 10 g of polyamide 6 powder was added into a zirconia ball milling jar and 40 g of zirconia ball milling beads were added, and then the mixture was ball milled at a speed of 600 rpm for 2 h to obtain a uniform spinning raw material;

[0095] The uniform spinning raw material is placed in a vacuum oven at a temperature of 100° C. for drying for 24 hours to obtain a dried spinning raw material;

[0096] The dried spinning raw material is subjected to spinning treatment at 235° C. by a melt spinning method to obtain a primary fiber;

[0097] The spun fibers were drawn by a hot roller at 140° C. to obtain polyamide 6 fibers.

[0098] Table 1 The mass of TpPa-COF, the mass of AM-COF and the mass of polyamide 6 in each embodiment and each comparative example

[0099] project TpPa-COF(mg) AM-COF(mg) Polyamide 6(g) Example 1 30 0 10 Example 2 50 0 10 Example 3 100 0 10 Example 4 200 0 10 Comparative Example 1 10 0 10 Comparative Example 2 0 30 10 Comparative Example 3 0 50 10 Comparative Example 4 0 100 10 Comparative Example 5 0 200 10 Comparative Example 6 0 0 10

[0100] Test Example 1

[0101] This test example provides a morphology characterization experiment of a covalent organic framework and polyamide 6 composite fiber:

[0102] The covalent organic framework and polyamide 6 composite fiber in Example 3 of the present invention and the polyamide 6 fiber in Comparative Example 6 were tested by scanning electron microscope (SEM), and the test results were as follows: Figure 3 and Figure 4 shown.

[0103] Depend on Figure 3 and Figure 4 It can be seen that the surface morphology of the covalent organic framework material and polyamide 6 composite fibers is similar to that of polyamide 6 fibers. Both have smooth and regular surface morphology without obvious holes and have obvious fiber characteristics, indicating that the fibers are uniformly formed during the spinning process.

[0104] Test Example 2

[0105] This test example provides a performance characterization experiment of a covalent organic framework and polyamide 6 composite fiber:

[0106] The covalent organic framework and polyamide 6 composite fibers in Examples 1-4 of the present invention, the covalent organic framework and polyamide 6 composite fibers in Comparative Examples 1-5, and the polyamide 6 fiber in Comparative Example 6 were respectively used as fibers to be tested and the following tests were performed, and the test results are shown in Table 2;

[0107] Tensile strength / MPa: Take 5cm of the fiber to be tested, use anti-slip tape 1cm from both ends for anti-slip treatment, and perform a tensile test using a universal testing machine, where the tensile speed is 50mm / min;

[0108] Toughness / MJ·m -3 :The toughness of the fiber to be tested is obtained by integrating the fiber stress-strain tensile curve.

[0109] Table 2 Test results

[0110] project Tensile strength / MPa <![CDATA[Toughness / MJ·m -3 > Example 1 922 113 Example 2 1030 150 Example 3 1095 151 Example 4 1035 123 Comparative Example 1 765 80 Comparative Example 2 472 81 Comparative Example 3 566 122 Comparative Example 4 775 125 Comparative Example 5 494 47 Comparative Example 6 794 122

[0111] As can be seen from Table 2, the tensile strength of the covalent organic framework and polyamide 6 composite fibers in Examples 1-4 of the present invention is significantly improved compared with the polyamide 6 fibers in Comparative Example 6. Compared with the polyamide 6 fibers in Comparative Example 6, the covalent organic framework and polyamide 6 composite fibers in Examples 2-3 of the present invention have excellent tensile strength and excellent toughness, which can meet the requirements of ultra-high-end application fields for the toughness performance of fiber materials.

[0112] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a covalent organic framework and polyamide 6 composite fiber, characterized in that: The following steps are involved: The covalent organic framework powder and the polyamide 6 powder are mixed and added into a ball milling tank, and then ball milled by a ball mill to obtain a spinning raw material; The spinning raw material is sequentially subjected to drying treatment and spinning treatment to obtain primary fibers; The as-spun fibers are subjected to a drafting process to obtain the covalent organic framework and polyamide 6 composite fibers.

2. The method for preparing a covalent organic framework and polyamide 6 composite fiber according to claim 1, characterized in that: The covalent organic framework includes TpPa-COF, and the structural formula of the TpPa-COF is as shown in formula (1):

3. The method for preparing a covalent organic framework and polyamide 6 composite fiber according to claim 2, characterized in that: In the spinning raw material, the mass ratio of the TpPa-COF powder to the polyamide 6 powder is (0.03-0.2):

10.

4. The method for preparing a covalent organic framework and polyamide 6 composite fiber according to claim 3, characterized in that: In the spinning raw material, the mass ratio of the TpPa-COF powder to the polyamide 6 powder is (0.05-0.1):

10.

5. The method for preparing a covalent organic framework and polyamide 6 composite fiber according to claim 1, characterized in that: The covalent organic framework powder and the polyamide 6 powder are mixed and added into a ball milling jar, and then ball milled by a ball mill, including: The covalent organic framework powder and the polyamide 6 powder are mixed and added into a ball mill jar, and ball mill beads are added, and then the mixture is ball milled at a speed of 500 rpm to 700 rpm for 1 h to 3 h.

6. The method for preparing a covalent organic framework and polyamide 6 composite fiber according to claim 1, characterized in that: The drying process is carried out at a temperature of 80° C. to 100° C. and for a time of 18 h to 24 h.

7. The method for preparing a covalent organic framework and polyamide 6 composite fiber according to claim 1, characterized in that: The spinning treatment temperature is 230°C to 240°C.

8. The method for preparing a covalent organic framework and polyamide 6 composite fiber according to claim 1, characterized in that: The spun fibers are subjected to a drafting process, comprising: The as-spun fibers are stretched by a hot roller at 100° C. to 140° C.

9. A covalent organic framework and polyamide 6 composite fiber, characterized in that: The composite fiber is prepared by the method for preparing the covalent organic framework and polyamide 6 composite fiber according to any one of claims 1 to 8.

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