Modified ultra-high molecular weight polyethylene fiber as well as preparation method and application thereof

Abstract

The invention relates to the field of high polymer materials, and discloses a modified ultra-high molecular weight polyethylene fiber and a preparation method and application thereof.The method comprises the steps that ultra-high molecular weight polyethylene powder, an antioxidant and a solvent are mixed, a mixed solution is mixed with MIL-101, and the obtained mixed material is spun to obtain ultra-high molecular weight polyethylene fiber protofilaments; the preparation method comprises the following steps: in the presence of an initiator and a catalyst, reacting ultra-high molecular weight polyethylene fiber precursor with caprolactam to obtain a polymerized modified fiber precursor; carrying out at least one time of hot drafting on the polymerized modified fiber precursor to obtain a preliminarily modified fiber precursor; and in the presence of peroxide, reacting the preliminarily modified fiber precursor with a modifier. According to the method, the ultra-high molecular weight polyethylene fiber is filled with the metal organic framework, and then polymerization modification and crosslinking modification are performed, so that the creep resistance of the fiber material is improved, and the application range of the ultra-high molecular weight polyethylene fiber is expanded.

Description

Technical Field

[0001] The invention relates to the field of polymer materials, and in particular to a modified ultra-high molecular weight polyethylene fiber and a preparation method and application thereof. Background Art

[0002] Ultra-high molecular weight polyethylene (UHMWPE) is a linear thermoplastic with excellent performance. The plastic is an unbranched linear polymer formed by coordination polymerization of ethylene monomers under the action of a catalyst. Due to its excellent mechanical properties, low density, friction resistance, self-lubrication, high chemical resistance, excellent biocompatibility and high impact toughness, it is widely used in biomedicine, textiles, military and aerospace fields. As one of the most important products, UHMWPE fiber has a high strength-to-weight ratio, good toughness, chemical resistance and wear resistance, and is widely used in military equipment and sports equipment.

[0003] However, UHMWPE itself is very sensitive to thermal influences, easy to melt and deform, and has low mechanical strength. During long-term use, ultra-high molecular weight polyethylene fibers are prone to deformation under high temperature or stress, which seriously reduces the service life. In addition, since UHMWPE macromolecules are linear flexible macromolecules, the force between molecular chains is small and slippage is easy to occur, resulting in poor creep resistance of UHMWPE fibers. In order to improve its creep resistance and plasticity, it is necessary to strengthen the performance of ultra-high molecular weight polyethylene through modification. Therefore, it is of great practical significance to study and develop a method for modifying ultra-high molecular weight polyethylene to improve its creep resistance. Summary of the invention

[0004] The purpose of the present invention is to overcome the problems of poor creep resistance of ultra-high molecular weight polyethylene fibers in the prior art, and to provide a modified ultra-high molecular weight polyethylene fiber and a preparation method and application thereof. The method uses a metal organic framework material to fill the ultra-high molecular weight polyethylene fiber, and then performs polymerization modification and cross-linking modification, thereby improving the creep resistance of the fiber material and further expanding the application range of the ultra-high molecular weight polyethylene fiber, which has very important social significance and significant economic benefits.

[0005] In order to achieve the above object, the present invention provides a method for preparing modified ultra-high molecular weight polyethylene fiber, which comprises the following steps:

[0006] (1) mixing ultra-high molecular weight polyethylene powder, an antioxidant and a solvent, mixing the obtained mixed solution with a metal organic framework material MIL-101, and then spinning the obtained mixture to obtain ultra-high molecular weight polyethylene fiber precursor;

[0007] (2) reacting the ultra-high molecular weight polyethylene fiber precursor with caprolactam monomer in a non-protonic polar solvent in the presence of an initiator and a catalyst to obtain a polymerized modified fiber precursor;

[0008] (3) subjecting the polymerized modified fiber precursor to at least one heat drawing to obtain a preliminary modified fiber precursor;

[0009] (4) reacting the preliminary modified fiber precursor with a modifying agent in the presence of a peroxide;

[0010] Wherein, the initiator is an isocyanate compound, the catalyst is sodium caprolactam and / or caprolactam magnesium bromide, and the modifier is selected from one or more of acrylamide, hydroxyethyl methacrylate, acrylate, and styrene.

[0011] Preferably, the metal organic framework material MIL-101 is selected from one or more of MIL-101 (Cr), MIL-101 (Fe) and MIL-101 (Al).

[0012] Preferably, the molecular weight of the ultra-high molecular weight polyethylene powder is 800,000-10,000,000.

[0013] Preferably, the weight ratio of the ultra-high molecular weight polyethylene powder to the metal organic framework material MIL-101 is 1:0.005-0.01.

[0014] Preferably, in step (2), the reaction conditions include: temperature of 120-150° C. and time of 30-80 min.

[0015] Preferably, the weight ratio of the initiator, the catalyst, the caprolactam monomer and the MIL-101 is 0.8-3:0.5-1.2:100:5-30.

[0016] Preferably, the antioxidant is antioxidant 1010 and / or antioxidant 1076.

[0017] Preferably, the aprotic polar solvent is selected from one or more of acetone, toluene and xylene.

[0018] Preferably, the initiator is selected from one or more of diphenylmethane diisocyanate, isophorone diisocyanate and toluene diisocyanate.

[0019] Preferably, the peroxide is selected from one or more of tert-butyl peroxide, benzoyl peroxide, diisopropylbenzene hydroperoxide and diisopropylbenzene peroxide.

[0020] Preferably, the weight ratio of the peroxide to the primary modified fiber precursor is 0.003-0.008:1.

[0021] Preferably, the weight ratio of the modifier to the preliminarily modified fiber precursor is 1:15-80.

[0022] Preferably, the specific process of step (3) includes: sequentially subjecting the polymer modified fiber precursor to one stretching, one heat treatment, two stretching, two heat treatments, three stretchings, three heat treatments, four stretchings, four heat treatments and five stretchings.

[0023] Preferably, the temperature during the first heat treatment is 130°C to 150°C, the temperature during the second heat treatment is 130°C to 150°C, the temperature during the third heat treatment is 135°C to 165°C, and the temperature during the fourth heat treatment is 135°C to 165°C.

[0024] The second aspect of the present invention provides modified ultra-high molecular weight polyethylene fiber prepared by the above method.

[0025] The third aspect of the present invention provides the application of the modified ultra-high molecular weight polyethylene fiber in textile, biomedicine, military and aerospace.

[0026] The method of the present invention first uses an organic metal framework material to blend and fill ultra-high molecular weight polyethylene fibers, then polymerizes caprolactam monomers with the filled organic metal framework material, adds side chains to the molecular chains of the ultra-high molecular weight polyethylene fibers, thereby increasing the steric hindrance between molecules and improving the creep resistance of the fiber material, and further forms a coating with a three-dimensional network structure on the surface of the ultra-high molecular weight polyethylene fibers by chemical crosslinking, thereby further improving the creep resistance of the ultra-high molecular weight polyethylene fibers. DETAILED DESCRIPTION

[0027] The specific embodiments of the present invention are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0028] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0029] The method for preparing modified ultra-high molecular weight polyethylene fiber of the present invention comprises the following steps:

[0030] (1) mixing ultra-high molecular weight polyethylene powder, an antioxidant and a solvent, mixing the obtained mixture with MIL-101, and then spinning the obtained mixture to obtain ultra-high molecular weight polyethylene fiber precursor;

[0031] (2) reacting the ultra-high molecular weight polyethylene fiber precursor with caprolactam monomer in a non-protonic polar solvent in the presence of an initiator and a catalyst to obtain a polymerized modified fiber precursor;

[0032] (3) subjecting the polymerized modified fiber precursor to at least one heat drawing to obtain a preliminary modified fiber precursor;

[0033] (4) reacting the preliminarily modified fiber precursor with a modifying agent in the presence of a peroxide.

[0034] In the method described in the present invention, since the molecular chains of ultra-high molecular weight polyethylene are highly entangled in the solution and remain in this state after the solution is spun and cooled, in step (1), ultra-high molecular weight polyethylene powder, antioxidant and solvent are mixed, the ultra-high molecular weight polyethylene powder is swollen in the solvent, and the antioxidant is used to prevent the oxidation of the ultra-high molecular weight polyethylene powder.

[0035] In the method described in the present invention, the molecular weight of the modified ultra-high molecular weight polyethylene is not limited. Preferably, the molecular weight of the ultra-high molecular weight polyethylene powder is 800,000-10,000,000.

[0036] In a preferred embodiment, in step (1), the solvent used is selected from one or more of liquid paraffin, decalin, mineral oil and white oil.

[0037] In a preferred embodiment, the antioxidant is antioxidant 1010 and / or antioxidant 1076, preferably antioxidant 1010. Specifically, the weight ratio of the antioxidant to the ultra-high molecular weight polyethylene powder is 0.003-0.005:1.

[0038] In a specific embodiment, the usage relationship between the solvent and the ultra-high molecular weight polyethylene powder can refer to conventional techniques in the art.

[0039] In the method described in the present invention, in step (1), the metal organic framework material MIL-101 is used for filling modification, and the doped metal organic framework material may form physical cross-linking points between the molecular chains of the ultra-high molecular weight polyethylene, increase the steric hindrance between molecules, and thus improve the creep resistance of the ultra-high molecular weight polyethylene fiber.

[0040] In the method described in the present invention, the metal organic framework material MIL-101 can be selected from one or more of MIL-101 (Cr), MIL-101 (Fe) and MIL-101 (Al). It can be understood that MIL-101 (Cr) means that the metal atom in the metal organic framework material is Cr. In a specific embodiment, the metal organic framework material MIL-101 can be a commercially available product or a product prepared by a common method in the art.

[0041] In a preferred embodiment, in order to further improve the creep resistance of the modified ultra-high molecular weight polyethylene fiber, the particle size of the metal organic framework material MIL-101 is 40-80 nm.

[0042] In a preferred embodiment, the weight ratio of the ultra-high molecular weight polyethylene powder to the metal organic framework material MIL-101 is 1:0.005-0.01, preferably 1:0.006-0.008. Specifically, the weight ratio of the ultra-high molecular weight polyethylene powder to the metal organic framework material MIL-101 can be 1:0.005, 1:0.006, 1:0.007, 1:0.008, 1:0.009 or 1:0.01.

[0043] In a specific embodiment, in step (1), the obtained mixture can be spun according to the existing technology to obtain ultra-high molecular weight polyethylene fiber precursor, and the specific spinning operation is not limited. For example, it can be wet spinning or dry spinning. The post-spinning treatment process and drying process can also refer to the conventional technology in the field.

[0044] In the method described in the present invention, the metal organic framework material has a regular structure and good thermal stability. The metal organic framework material is mixed with the material after the ultra-high molecular weight polyethylene is swollen, and then the metal organic framework material is further filled into the ultra-high molecular weight polyethylene precursor fiber by spinning. The filled metal organic framework material may play a role of physical cross-linking within the molecule, thereby increasing the spatial resistance between molecules to a certain extent, thereby improving the creep resistance of the fiber material.

[0045] In the method of the present invention, the initiator is an isocyanate compound, and the isocyanate compound is selected from one or more of diphenylmethane diisocyanate, isophorone diisocyanate and toluene diisocyanate; the catalyst is sodium caprolactam and / or caprolactam magnesium bromide. In step (2), the metal organic framework material MIL-101 filled in the ultra-high molecular weight polyethylene fiber precursor is promoted to undergo polymerization reaction with the caprolactam monomer through the action of the initiator and the catalyst, and the macromolecular polymer chain segment is connected with the metal organic framework material through the polymerization reaction, and the modified monomer is introduced to increase the content of the side chain group in the ultra-high molecular weight polyethylene fiber precursor, further increase the steric hindrance of the molecular chain in the ultra-high molecular weight polyethylene fiber precursor, prevent the slip between molecules, and enhance the thermal stability and creep resistance of the prepared modified ultra-high molecular weight polyethylene fiber.

[0046] In a preferred embodiment, in step (2), the reaction conditions include: temperature of 120-150°C, time of 30-80 min, preferably 35-60 min. Specifically, the reaction temperature can be 120°C, 130°C, 140°C or 150°C; the reaction time can be 30 min, 50 min, 60 min, 70 min or 80 min.

[0047] In a specific embodiment, in step (2), the reaction is carried out under vacuum conditions.

[0048] In a preferred embodiment, the weight ratio of the initiator, the catalyst, the caprolactam monomer and the metal frame material MIL-101 is 0.8-3:0.5-1.2:100:5-30, preferably 0.85-2:0.5-1.2:100:10-30.

[0049] In a preferred embodiment, the aprotic polar solvent is selected from one or more of acetone, toluene and xylene, preferably acetone.

[0050] In a specific embodiment, the specific process of step (3) is as follows: placing the polymer modified fiber precursor on a wire guide frame, and then feeding the polymer modified fiber precursor on the wire guide frame into a first seven-roller drawing machine at a certain speed for primary stretching, and then conveying it to a first stretching hot box for primary heat treatment after the primary stretching; then conveying it to a second seven-roller drawing machine for secondary stretching, and then conveying it to a second stretching hot box for secondary heat treatment after the secondary stretching; then conveying it to a third seven-roller drawing machine for tertiary stretching, and then conveying it to a third stretching hot box for tertiary heat treatment after the third stretching; then conveying it to a fourth seven-roller drawing machine for quaternary stretching, and then conveying it to a fourth stretching hot box for quaternary heat treatment after the fourth stretching; then conveying it to a fifth seven-roller drawing machine for quintuple stretching to obtain a preliminary modified fiber precursor. Through multiple hot stretching treatments, the polyethylene macromolecules in the polymer modified fiber precursor can be stretched and straightened along the stretching direction, and the macromolecular orientation and crystallinity are significantly improved, thereby giving the fiber excellent mechanical properties and creep resistance.

[0051] In a preferred embodiment, the temperature during the first heat treatment is 130°C to 150°C, preferably 135°C to 140°C; the temperature during the second heat treatment is 130°C to 150°C, preferably 135°C to 140°C; the temperature during the third heat treatment is 135°C to 165°C, preferably 140°C to 150°C; the temperature during the fourth heat treatment is 135°C to 165°C, preferably 140°C to 150°C.

[0052] In a preferred embodiment, the stretching speed of the first seven-roller stretching machine is 1.0 m / min to 4.0 m / min; the stretching speed of the second seven-roller stretching machine is 1.0 m / min to 4.0 m / min; the stretching speed of the third seven-roller stretching machine is 5.0 m / min to 10.0 m / min; the stretching speed of the fourth seven-roller stretching machine is 5.0 m / min to 15.0 m / min; the stretching speed of the fifth seven-roller stretching machine is 10.0 m / min to 20.0 m / min.

[0053] In the method of the present invention, the modifier can be selected from one or more of acrylamide, hydroxyethyl methacrylate, acrylate, and styrene.

[0054] In the method described in the present invention, by using peroxide as a cross-linking agent, a three-dimensional network structure is generated on the surface of the fiber material through a cross-linking reaction without destroying the structure of the preliminary modified fiber precursor itself, thereby further improving the thermal stability and high temperature resistance of the ultra-high molecular weight polyethylene fiber, making it less likely to soften, deform or decompose in a high temperature environment, slowing down the aging rate of the material, extending the service life of the material, and improving its stability and reliability in harsh environments.

[0055] In a preferred embodiment, the peroxide is selected from one or more of tert-butyl peroxide, benzoyl peroxide, diisopropylbenzene hydroperoxide and diisopropylbenzene peroxide.

[0056] In a preferred embodiment, the weight ratio of the peroxide to the preliminary modified fiber precursor is 0.003-0.008: 1, preferably 0.004-0.005: 1. Specifically, the weight ratio of the peroxide to the preliminary modified fiber precursor can be 0.003: 1, 0.0035: 1, 0.004: 1, 0.005: 1, 0.006: 1, 0.007: 1 or 0.008: 1.

[0057] In a preferred embodiment, the weight ratio of the modifier to the preliminary modified fiber precursor is 1:15-80, preferably 1:30-60. Specifically, the weight ratio of the modifier to the preliminary modified fiber precursor can be 1:15, 1:20, 1:25, 1:30, 1:35, 1:40, 1:50, 1:60, 1:70 or 1:80.

[0058] In a specific embodiment, in step (4), the reaction conditions include: temperature of 160-180° C., and time of 30-60 min.

[0059] In a specific embodiment, in step (4), the fiber-on-liquid device is used to cause the preliminary modified fiber precursor to contact and react with the modifier. The fiber-on-liquid device is filled with peroxide, modifier and water (water is used as a solvent to dissolve the peroxide and the modifier). The fiber-on-liquid device makes the preliminary modified fiber precursor fully contact with the material in the fiber-on-liquid device by rolling the liquid wheel, thereby achieving the purpose of fiber modification. More specifically, the fiber-on-liquid device is also provided with a hydraulic roller inside, and a heat-insulating jacket, an electric heating belt and a wire guide are provided on the outside. The jacket is filled with heat-conducting oil for heating the reaction.

[0060] The present invention further provides a modified ultra-high molecular weight polyethylene fiber prepared by the above method. The modified ultra-high molecular weight polyethylene fiber prepared by the present invention has excellent creep resistance, effectively improves the performance of the ultra-high molecular weight polyethylene fiber, promotes industrial upgrading, increases product added value, and meets the demand for high-performance composite materials.

[0061] The present invention also provides the application of the modified ultra-high molecular weight polyethylene fiber in textile, biomedicine, military and aerospace. The modified ultra-high molecular weight polyethylene fiber has excellent creep resistance, excellent stability and reliability in harsh environments, and can be applied in many fields, with broad application prospects and economic value.

[0062] The present invention will be described in detail below through examples, but the protection scope of the present invention is not limited thereto.

[0063] In the present invention, the experimental methods in the following examples, unless otherwise specified, are all conventional methods in the art. The experimental materials used in the following examples, unless otherwise specified, are all commercially available.

[0064] Example 1

[0065] (1) dissolving an antioxidant 1010 in liquid paraffin, then adding ultra-high molecular weight polyethylene powder and performing shear stirring and swelling at 100° C. for 24 hours, stirring and mixing the obtained mixed solution with a metal organic framework material MIL-101(Fe) for 1 hour, and then extruding the obtained mixture using a twin-screw extruder, cooling it through a water tank, and then pre-stretching it on a winder to obtain an ultra-high molecular weight polyethylene fiber precursor; wherein the weight ratio of the ultra-high molecular weight polyethylene powder to the MIL-101(Fe) is 1:0.006;

[0066] (2) Under vacuum conditions, caprolactam monomer, diphenylmethane diisocyanate and sodium caprolactam are dissolved in acetone, and then the obtained mixture is mixed with ultra-high molecular weight polyethylene fiber precursor for reaction at a reaction temperature of 130° C. and a reaction time of 40 min to obtain a polymerized modified fiber precursor; wherein the weight ratio of diphenylmethane diisocyanate, sodium caprolactam, caprolactam monomer and metal frame material MIL-101 (Fe) is 1.5:0.8:100:25;

[0067] (3) placing the polymerized modified fiber precursor on a guide wire rack, and then feeding the polymerized modified fiber precursor on the guide wire rack into a first seven-roller drawing machine for primary stretching (speed of 1.28 m / min), and after the primary stretching, conveying the polymerized modified fiber precursor to a first stretching hot box for primary heat treatment (temperature of 138° C.); then conveying the polymerized modified fiber precursor to a second seven-roller drawing machine for secondary stretching (speed of 1.28 m / min), and after the secondary stretching, conveying the polymerized modified fiber precursor to a second stretching hot box for secondary heat treatment (temperature of 140° C.); then conveying the polymerized modified fiber precursor to a second seven-roller drawing machine for secondary stretching (speed of 1.28 m / min), and ... The third seven-roller drawing machine is stretched three times (speed is 7.69m / min), and after the three stretchings, it is transported to the third drawing hot box for three heat treatments (temperature is 145°C); then it is transported to the fourth seven-roller drawing machine for four stretchings (speed is 9.76m / min), and after the four stretchings, it is transported to the fourth drawing hot box for four heat treatments (temperature is 148°C); then it is transported to the fifth seven-roller drawing machine for five stretchings (speed is 11.30m / min), to obtain preliminary modified fiber precursor;

[0068] (4) Dissolving diisopropylbenzene peroxide and acrylamide in water, and then immersing the preliminary modified fiber precursor in the mixed solution and reacting at 160° C. for 40 minutes. After the reaction, the fiber is taken out, cleaned and dried to obtain a modified ultra-high molecular weight polyethylene fiber; wherein the weight ratio of diisopropylbenzene peroxide to the preliminary modified fiber precursor is 0.0045:1; and the weight ratio of acrylamide to the preliminary modified fiber precursor is 1:40.

[0069] Example 2

[0070] (1) dissolving an antioxidant 1010 in liquid paraffin, then adding ultra-high molecular weight polyethylene powder and performing shear stirring and swelling at 100° C. for 24 hours, stirring and mixing the obtained mixture with MIL-101(Cr) for 1 hour, and then extruding the obtained mixture by a twin-screw extruder, cooling it in a water tank, and then pre-stretching it on a winder to obtain an ultra-high molecular weight polyethylene fiber precursor; wherein the weight ratio of the ultra-high molecular weight polyethylene powder to the MIL-101(Cr) is 1:0.007;

[0071] (2) Under vacuum conditions, caprolactam monomer, isophorone diisocyanate and sodium caprolactam are dissolved in acetone, and then the obtained mixture is mixed with ultra-high molecular weight polyethylene fiber precursor for reaction at a reaction temperature of 130° C. for a reaction time of 40 min to obtain a polymerized modified fiber precursor; wherein the weight ratio of isophorone diisocyanate, sodium caprolactam, caprolactam monomer and metal frame material MIL-101 (Cr) is 1.3:1:100:20;

[0072] (3) placing the polymerized modified fiber precursor on a guide wire rack, and then feeding the polymerized modified fiber precursor on the guide wire rack into a first seven-roller drawing machine for primary stretching (speed of 2.12 m / min), and after the primary stretching, conveying the polymerized modified fiber precursor to a first stretching hot box for primary heat treatment (temperature of 135° C.); then conveying the polymerized modified fiber precursor to a second seven-roller drawing machine for secondary stretching (speed of 2.12 m / min), and after the secondary stretching, conveying the polymerized modified fiber precursor to a second stretching hot box for secondary heat treatment (temperature of 140° C.); then conveying the polymerized modified fiber precursor to a second seven-roller drawing machine for secondary stretching (speed of 2.12 m / min), and conveying the polymerized modified fiber precursor to a second seven-roller drawing machine ... stretching (speed of 2.12 m / min), and conveying the polymerized modified fiber precursor to a second seven-roller drawing hot box for secondary heat treatment (temperature of 140° C.); The third seven-roller drawing machine is stretched three times (speed is 8.69m / min), and after the three stretchings, it is transported to the third drawing hot box for three heat treatments (temperature is 148°C); then it is transported to the fourth seven-roller drawing machine for four stretchings (speed is 9.76m / min), and after the four stretchings, it is transported to the fourth drawing hot box for four heat treatments (temperature is 148°C); then it is transported to the fifth seven-roller drawing machine for five stretchings (speed is 10.2m / min), and a preliminary modified fiber precursor is obtained;

[0073] (4) dissolving benzoyl peroxide and acrylamide in water, and then immersing the preliminary modified fiber precursor in the mixed solution and reacting at 160° C. for 40 minutes. After the reaction, the fiber is taken out, cleaned and dried to obtain a modified ultra-high molecular weight polyethylene fiber; wherein the weight ratio of diisopropylbenzene hydroperoxide to the preliminary modified fiber precursor is 0.0048:1; and the weight ratio of acrylamide to the preliminary modified fiber precursor is 1:30.

[0074] Example 3

[0075] (1) dissolving an antioxidant 1010 in liquid paraffin, then adding ultra-high molecular weight polyethylene powder and performing shear stirring and swelling at 100° C. for 24 hours, stirring and mixing the obtained mixture with MIL-101 (Al) for 1 hour, and then extruding the obtained mixture by a twin-screw extruder, cooling it in a water tank, and then pre-stretching it on a winder to obtain an ultra-high molecular weight polyethylene fiber precursor; wherein the weight ratio of the ultra-high molecular weight polyethylene powder to the MIL-101 (Al) is 1:0.0085;

[0076] (2) Under vacuum conditions, caprolactam monomer, toluene diisocyanate and caprolactam magnesium bromide are dissolved in acetone, and then the obtained mixture is mixed with ultra-high molecular weight polyethylene fiber precursor for reaction at a reaction temperature of 130° C. for a reaction time of 40 min to obtain a polymerized modified fiber precursor; wherein the weight ratio of toluene diisocyanate, caprolactam magnesium bromide, caprolactam monomer and metal frame material MIL-101 (Cr) is 1.8:0.9:100:15;

[0077] (3) placing the polymerized modified fiber precursor on a guide wire rack, and then feeding the polymerized modified fiber precursor on the guide wire rack into a first seven-roller drawing machine for primary stretching (speed of 1.59 m / min), and after the primary stretching, conveying the polymerized modified fiber precursor to a first stretching hot box for primary heat treatment (temperature of 136° C.); then conveying the polymerized modified fiber precursor to a second seven-roller drawing machine for secondary stretching (speed of 1.59 m / min), and after the secondary stretching, conveying the polymerized modified fiber precursor to a second stretching hot box for secondary heat treatment (temperature of 138° C.); then conveying the polymerized modified fiber precursor to a second seven-roller drawing machine for secondary stretching (speed of 1.59 m / min), and ... stretching (speed of 1.59 m / min), and conveying the polymerized modified fiber precursor to a second The third seven-roller drawing machine is stretched three times (speed is 8.12m / min), and after the three stretchings, it is transported to the third drawing hot box for three heat treatments (temperature is 145°C); then it is transported to the fourth seven-roller drawing machine for four stretchings (speed is 9.36m / min), and after the four stretchings, it is transported to the fourth drawing hot box for four heat treatments (temperature is 148°C); then it is transported to the fifth seven-roller drawing machine for five stretchings (speed is 13.2m / min), and a preliminary modified fiber precursor is obtained;

[0078] (4) Dissolving diisopropylbenzene hydroperoxide and acrylamide in water, then immersing the preliminary modified fiber precursor in the mixed solution and reacting at 160° C. for 40 minutes, and after the reaction, taking out the fiber, cleaning it and drying it to obtain a modified ultra-high molecular weight polyethylene fiber; wherein the weight ratio of diisopropylbenzene hydroperoxide to the preliminary modified fiber precursor is 0.0055:1; and the weight ratio of acrylamide to the preliminary modified fiber precursor is 1:45.

[0079] Example 4

[0080] The method of Example 1 is followed, except that in step (4), the weight ratio of dicumyl peroxide to the preliminary modified fiber precursor is 0.002:1.

[0081] Example 5

[0082] The method of Example 1 is followed, except that in step (4), the weight ratio of dicumyl peroxide to the preliminary modified fiber precursor is 0.006:1.

[0083] Comparative Example 1

[0084] The method of Example 1 was followed, except that the metal organic framework material MIL-101 (Fe) was replaced with an equal weight of SiO2 for preparation.

[0085] Comparative Example 2

[0086] The method of Example 1 is followed, except that the reaction of step (2) is not carried out, that is, the ultra-high molecular weight polyethylene fiber precursor prepared in step (1) is directly subjected to the modification process of steps (3) and (4).

[0087] Comparative Example 3

[0088] The method of Example 1 is followed, except that step (3) is not performed, and the polymerized modified fiber precursor obtained in step (2) is directly subjected to the modification process of step (4).

[0089] Comparative Example 4

[0090] The method of Example 1 is followed, except that step (4) is not performed, that is, the subsequent modification process is stopped after the preliminary modified fiber precursor is obtained.

[0091] Comparative Example 5

[0092] The method of Example 1 is followed, except that no peroxide is added to carry out the reaction in step (4).

[0093] Test Case

[0094] The creep resistance and tensile strength of the modified ultra-high molecular weight polyethylene fibers prepared in Examples 1-5 and Comparative Examples 1-5 were tested. The test results are shown in Table 1.

[0095] Creep resistance test method: Place the sample in a standard test atmosphere for at least 48 hours in a relaxed but untwisted state, then clamp one end of the sample into a clamp and clamp the other end into another clamp without untwisting. Apply pretension (initial load), mark points on the sample, and make the mark length at least 200mm, then observe and record the initial mark length of the sample, i.e., the initial length L0, then apply a heavy load, observe and record the length of the sample after a certain period of time or the final fracture length L1, and calculate the creep resistance of the sample according to the formula shown in formula 1;

[0096]

[0097] Where G is the tensile creep elongation (%), L0 is the initial length of the specimen (mm), and L1 is the length of the specimen after heavy load is applied or the final breaking length (mm);

[0098] The tensile strength is tested according to the method of national standard GB / T 19975-2005.

[0099] Table 1

[0100] Example No. Tensile strength (cN / dtex) Tensile creep elongation (%) Example 1 35.79 5.34 Example 2 35.23 5.85 Example 3 34.68 6.47 Example 4 33.47 6.88 Example 5 33.56 6.75 Comparative Example 1 30.15 8.32 Comparative Example 2 30.66 8.13 Comparative Example 3 32.47 7.58 Comparative Example 4 31.21 7.96 Comparative Example 5 32.03 7.85

[0101] It can be seen from the results in Table 1 that the modified ultra-high molecular weight polyethylene fiber prepared by the method described in the present invention has excellent tensile strength and creep resistance, has better performance, and has broader application prospects.

[0102] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for preparing modified ultra-high molecular weight polyethylene fiber, characterized in that: The method comprises the following steps: (1) mixing ultra-high molecular weight polyethylene powder, an antioxidant and a solvent, mixing the obtained mixed solution with a metal organic framework material MIL-101, and then spinning the obtained mixture to obtain ultra-high molecular weight polyethylene fiber precursor; (2) reacting the ultra-high molecular weight polyethylene fiber precursor with caprolactam monomer in a non-protonic polar solvent in the presence of an initiator and a catalyst to obtain a polymerized modified fiber precursor; (3) subjecting the polymerized modified fiber precursor to at least one heat drawing to obtain a preliminary modified fiber precursor; (4) reacting the preliminary modified fiber precursor with a modifying agent in the presence of a peroxide; Wherein, the initiator is an isocyanate compound, the catalyst is sodium caprolactam and / or caprolactam magnesium bromide, and the modifier is selected from one or more of acrylamide, hydroxyethyl methacrylate, acrylate, and styrene.

2. The method according to claim 1, characterized in that The metal organic framework material MIL-101 is selected from one or more of MIL-101 (Cr), MIL-101 (Fe) and MIL-101 (Al); and / or The molecular weight of the ultra-high molecular weight polyethylene powder is 800,000-10,000,000.

3. The method according to claim 1, characterized in that The weight ratio of the ultra-high molecular weight polyethylene powder to the metal organic framework material MIL-101 is 1:0.005-0.

01.

4. The method according to claim 1 or 3, characterized in that: The weight ratio of the initiator, the catalyst, the caprolactam monomer and the metal organic framework material MIL-101 is 0.8-3:0.5-1.2:100:5-30; and / or In step (2), the reaction conditions include: temperature of 120-150° C. and time of 30-80 min.

5. The method according to claim 1, characterized in that The antioxidant is antioxidant 1010 and / or antioxidant 1076; and / or The aprotic polar solvent is selected from one or more of acetone, toluene and xylene; and / or The initiator is selected from one or more of diphenylmethane diisocyanate, isophorone diisocyanate and toluene diisocyanate.

6. The method according to claim 1, characterized in that The peroxide is one or more selected from tert-butyl peroxide, benzoyl peroxide, diisopropylbenzene hydroperoxide and diisopropylbenzene peroxide; and / or The weight ratio of the peroxide to the primary modified fiber precursor is 0.003-0.008:

1.

7. The method according to claim 1, characterized in that The weight ratio of the modifier to the preliminarily modified fiber precursor is 1:15-80.

8. The method according to claim 1, characterized in that The specific process of step (3) includes: sequentially subjecting the polymerized modified fiber precursor to a first stretching, a first heat treatment, a second stretching, a second heat treatment, a third stretching, a third heat treatment, a fourth stretching, a fourth heat treatment and a fifth stretching; Preferably, the temperature during the first heat treatment is 130°C to 150°C, the temperature during the second heat treatment is 130°C to 150°C, the temperature during the third heat treatment is 135°C to 165°C, and the temperature during the fourth heat treatment is 135°C to 165°C.

9. The modified ultra-high molecular weight polyethylene fiber prepared according to the method of any one of claims 1 to 8.

10. Application of the modified ultra-high molecular weight polyethylene fiber according to claim 9 in textile, biomedicine, military and aerospace.

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