LCP (Liquid Crystal Polymer) resin synthesized by applying microchannel continuous flow reaction process, LCP fiber and synthesis method of LCP resin and LCP fiber

Abstract

The invention discloses an LCP (Liquid Crystal Polymer) resin synthesized by applying a microchannel continuous flow reaction process, an LCP fiber and a synthesis method of the LCP resin and the LCP fiber. Wherein the LCP resin is obtained by introducing a flame-retardant modifier into an LCP prepolymer, namely, adding an LCP resin prepolymer into a continuous polycondensation reaction kettle, and adding the flame-retardant modifier for polycondensation reaction. Four benzene rings in the flame-retardant modifier structure are chemically connected with molecular chains in the LCP resin through P atoms, so that the interaction force between the molecular chains can be optimized, and the mechanical property and flame-retardant property of the product are further effectively improved.

Description

Technical Field

[0001] The invention relates to the technical field of liquid crystal macromolecular polymers, and in particular to an LCP resin and LCP fiber synthesized by using a microchannel continuous flow reaction process and a synthesis method thereof. Background Art

[0002] Liquid crystal polymer (LCP) is a special polymer material with high strength, high modulus, excellent molding and processing performance, outstanding heat resistance, low water absorption, low dielectric constant and dielectric loss factor, etc. It is widely used in electronic appliances, 5G communications, consumer electronics, automotive parts, aerospace, national defense and military and other technical fields. At present, the polymerization method of LCP resin is mainly based on melt polycondensation, but most of the existing melt polycondensation is carried out in a kettle reactor, which is difficult to achieve continuous production. In addition, due to poor temperature control during the synthesis process, more by-products will be produced, which seriously affects the purity and quality of the product. Summary of the invention

[0003] In order to overcome the above-mentioned shortcomings, the purpose of the present invention is to provide an LCP resin, LCP fiber and a synthesis method thereof synthesized using a microchannel continuous flow reaction process, which can effectively improve the synthesis quality of the LCP resin and fiber.

[0004] In order to achieve the above object, the present invention provides a LCP resin, the structural formula of which is as follows:

[0005] Among them, X=30%-50%, Y=30%-50%, Z=20%-30%.

[0006] Specifically, the synthetic raw materials of the LCP resin include an LCP resin prepolymer and a flame retardant modifier.

[0007] Specifically, the flame retardant modifier is 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide.

[0008] To further explain, the structural formula of LCP resin prepolymer is as follows:

[0009] Among them, X=30%-50%, Y=30%-50%, Z=20%-30%.

[0010] Specifically, the raw materials include a benzene ring-containing monomer, a naphthalene ring-containing monomer, a functional monomer and a catalyst.

[0011] Furthermore, the molar mass ratio of the flame retardant modifier to the functional monomer is 1.5-2.4:1.

[0012] Preferably, the molar mass ratio of the flame retardant modifier to the functional monomer is 1.8-2.2:1.

[0013] Furthermore, the benzene ring-containing monomer includes at least one of p-hydroxybenzoic acid and terephthalic acid.

[0014] Furthermore, the naphthalene ring-containing monomer includes at least one of 2-hydroxy-6-naphthoic acid, 7-hydroxy-2-naphthoic acid, and 2,7-dihydroxynaphthalene.

[0015] Further, the functional monomer includes 4,4'-dihydroxybenzophenone.

[0016] Furthermore, the catalyst includes at least one of thionyl chloride and trifluoromethanesulfonic acid.

[0017] Specifically, the amount of the catalyst used is 0.1%-0.2% of the total mass of the benzene ring-containing monomer, the naphthalene ring-containing monomer, and the functional monomer.

[0018] Specifically, the molar mass ratio of the benzene ring-containing monomer, the naphthalene ring-containing monomer, and the functional monomer is 1:0.7-2:0.5-2.

[0019] Preferably, the molar mass ratio of the benzene ring-containing monomer, the naphthalene ring-containing monomer, and the functional monomer is 1:1-1.4:1-1.3.

[0020] In the molecular structure of the LCP resin of the present invention, a modifier with a flame retardant function is grafted onto the LCP resin molecular chain to avoid the problem of migration and precipitation of the flame retardant modifier affecting the mechanical properties and flame retardant properties of the resin in the traditional physical blending modification method. The four benzene rings on the side chain are connected to the molecular chain through the P atom, so that the four benzene rings on the side chain are arranged in a non-coplanar manner with the benzene rings on the molecular chain, which optimizes the interaction force between the macromolecular chains and is beneficial to the mechanical properties, temperature resistance and flame retardant properties of the product.

[0021] The present application also provides a method for synthesizing LCP resin using a microchannel continuous flow reaction process, comprising the following steps: adding an LCP resin prepolymer into a continuous polycondensation reactor, adding a flame retardant modifier to carry out a polycondensation reaction, and obtaining an LCP resin.

[0022] Preferably, the method for synthesizing LCP resin using a microchannel continuous flow reaction process comprises the following steps: adding LCP resin prepolymer into a continuous polycondensation reactor, filling with nitrogen to deoxygenate, and heating to 180-190°C; adding a flame retardant modifier, stirring and reacting for 2-3 hours, and then heating to 270-290°C for reaction for 1-2 hours to obtain LCP resin.

[0023] Specifically, the preparation steps of the LCP resin prepolymer include: (1) dissolving a benzene ring-containing monomer, a naphthalene ring-containing monomer, a functional monomer and a catalyst in an organic solution to obtain a benzene ring-containing monomer solution, a naphthalene ring-containing monomer solution, a functional monomer solution and a catalyst solution; (2) The benzene ring-containing monomer solution, the naphthalene ring-containing monomer solution, the functional monomer solution and the catalyst solution are pumped into a microchannel continuous flow reactor respectively to carry out an esterification reaction. After the reaction is completed, an LCP resin prepolymer is obtained through post-treatment.

[0024] Furthermore, in step (1), the organic solvent includes at least one of acetone, ether, and alcohol solvents.

[0025] Furthermore, in step (2), the temperature of the esterification reaction is 50-70°C, and the reaction time is 30-60 min.

[0026] Furthermore, in step (2), the microchannel continuous flow reactor is a tubular structure, and the hydraulic diameter of the channel is 10-20 mm; the flow rate of the benzene ring-containing monomer solution is 10-15 ml / min; the flow rate of the naphthalene ring-containing monomer solution is 10-15 ml / min; the flow rate of the functional monomer solution is 10-15 ml / min; and the flow rate of the catalyst solution is 0.1-0.2 ml / min.

[0027] In step (2), a microchannel continuous flow reactor is introduced to carry out solution polymerization reaction, which can solve the difficulty of slow heat transfer in the prepolymerization stage of LCP resin and ensure the rapid transfer of reaction heat to prevent explosion and generation of low molecular weight by-products caused by local overheating of the reaction system, thereby ensuring that the final LCP resin has good molecular dispersion and stable and controllable intrinsic viscosity.

[0028] The synthesis method of the invention can better combine the advantages of solution polymerization and melt polymerization. First, a benzene ring-containing monomer solution, a naphthalene ring-containing monomer solution and a functional monomer solution are subjected to solution polymerization through a microchannel continuous flow reactor to obtain an LCP resin prepolymer with uniform molecular weight. Then, the LCP resin prepolymer is subjected to solid-phase melt polycondensation through a continuous polycondensation reactor to greatly improve the molecular weight of the LCP resin, so that the molecular weight of the finally synthesized LCP resin is uniform and has high purity, meeting the application requirements of fiber-grade resins. Moreover, due to the addition of the functional monomer, a modifier with a flame retardant function can be directly grafted onto the LCP resin molecular chain during the melt polycondensation process, so as to avoid the problem that the flame retardant modifier migrates and precipitates due to physical blending modification in the prior art, thereby affecting the mechanical properties and flame retardant properties of the LCP resin.

[0029] Compared with the amplification effect of traditional reactors, the synthesis method for preparing fiber-grade LCP resin of the present invention does not require amplification effect, which is beneficial to industrial large-scale continuous production.

[0030] The present invention uses the above-mentioned LCP resin as a raw material to prepare LCP fiber, and its synthesis method comprises the following steps: (1) Adding LCP resin into a spinning device, and obtaining nascent fibers after melting, extrusion, and drawing; wherein the melting temperature is 300-320° C., and the drawing speed is 800-1000 m / min; (2) heat treating the spun fibers to obtain LCP fibers; wherein the heat treatment temperature is 260-280° C. and the time is 12-24 hours.

[0031] The present invention combines the advantages of solution polymerization and melt polymerization when synthesizing LCP resin using a microchannel continuous flow reaction process, thereby improving the synthesis quality of the LCP resin and further effectively improving the synthesis quality of the LCP fiber. DETAILED DESCRIPTION

[0032] The preferred embodiments of the present invention are described in detail below so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more explicit definition of the protection scope of the present invention. It should be noted that the following embodiments are for a better understanding of the present invention, are not limited to the best embodiments, and do not limit the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts shall fall within the protection scope of the present invention.

[0033] It should be noted that, in the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0034] In addition, if the specific experimental steps or conditions are not specified in the examples, the operations or conditions of the conventional experimental steps described in the literature in the art can be carried out. The numerical ranges shown by "-" in the examples indicate the ranges containing the values ​​recorded before and after the "-" as the minimum and maximum values, respectively. If the manufacturers of the reagents or instruments used are not specified, they are all conventional reagent products that can be obtained commercially.

[0035] The present invention provides a method for synthesizing LCP resin by using a microchannel continuous flow reaction process, comprising the following steps: (1) preparing a benzene ring-containing monomer solution, a naphthalene ring-containing monomer solution, a functional monomer solution and a catalyst solution respectively. Specifically, at room temperature, the benzene ring-containing monomer, the naphthalene ring-containing monomer, the functional monomer and the catalyst are dissolved in an organic solvent respectively to prepare a benzene ring-containing monomer solution, a naphthalene ring-containing monomer solution, a functional monomer solution and a catalyst solution; In some embodiments, the benzene ring-containing monomer includes at least one of p-hydroxybenzoic acid and terephthalic acid.

[0036] In some embodiments, the naphthalene ring-containing monomer includes at least one of 2-hydroxy-6-naphthoic acid, 7-hydroxy-2-naphthoic acid, and 2,7-dihydroxynaphthalene.

[0037] In some embodiments, the functional monomer includes 4,4'-dihydroxybenzophenone.

[0038] In some embodiments, the catalyst includes at least one of thionyl chloride and trifluoromethanesulfonic acid.

[0039] In some embodiments, the organic solvent includes at least one of acetone, ether, and alcohol solvents.

[0040] (2) The benzene ring-containing monomer solution, the naphthalene ring-containing monomer solution, the functional monomer solution and the catalyst solution are pumped into a microchannel continuous flow reactor respectively to carry out an esterification reaction. After the reaction is completed, an LCP resin prepolymer is obtained through post-treatment, and its structural formula is as follows:

[0041] Among them, X=30%-50%, Y=30%-50%, Z=20%-30%; In some embodiments, the molar mass ratio of the benzene ring-containing monomer, the naphthalene ring-containing monomer, and the functional monomer is 1:0.7-2:0.5-2.

[0042] In some embodiments, the molar mass ratio of the benzene ring-containing monomer, the naphthalene ring-containing monomer, and the functional monomer is 1:1-1.4:1-1.3.

[0043] In some embodiments, the amount of the catalyst used is 0.1%-0.2% of the total mass of the benzene ring-containing monomers, naphthalene ring-containing monomers, and functional monomers involved in the esterification reaction.

[0044] In some embodiments, in step (2), the microchannel continuous flow reactor is a tubular structure, and the hydraulic diameter of the channel is 10-20 mm; the flow rate of the benzene ring-containing monomer solution is 10-15 ml / min; the flow rate of the naphthalene ring-containing monomer solution is 10-15 ml / min; the flow rate of the functional monomer solution is 10-15 ml / min; and the flow rate of the catalyst solution is 0.1-0.2 ml / min.

[0045] In some embodiments, the temperature of the esterification reaction is 50-70° C., and the reaction time is 30-60 min. Post-treatment includes distilling the reaction solution under reduced pressure to remove the reaction solvent, and drying to obtain the LCP resin prepolymer.

[0046] (3) Adding the LCP resin prepolymer into a continuous polycondensation reactor, adding a flame retardant modifier to carry out a polycondensation reaction, so as to obtain an LCP resin, the structural formula of which is as follows:

[0047] Among them, X=30%-50%, Y=30%-50%, Z=20%-30%.

[0048] In some embodiments, step (3) specifically includes adding the LCP resin prepolymer into a continuous polycondensation reactor, filling it with nitrogen to deoxygenate and heating it to 180-190°C; adding a flame retardant modifier, stirring and reacting for 2-3 hours, and then heating it to 270-290°C for 1-2 hours to obtain the LCP resin.

[0049] In some embodiments, the flame retardant modifier is 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide.

[0050] In some embodiments, the molar mass ratio of the flame retardant modifier to the functional monomer is 1.5-2.4:1.

[0051] In some embodiments, the molar mass ratio of the flame retardant modifier to the functional monomer is 1.8-2.2:1.

[0052] The method for preparing LCP fiber using the above LCP resin comprises the following steps: (1) Adding the above LCP resin into a spinning device, and obtaining spun fibers after melting, extrusion and drawing; wherein the melting temperature is 300-320° C. and the drawing speed is 800-1000 m / min; (2) heat treating the spun fibers to obtain LCP fibers; wherein the heat treatment temperature is 260-280° C. and the time is 12-24 hours.

[0053] When synthesizing the LCP resin of this embodiment, a microchannel continuous flow reactor is used to carry out solution polymerization of each reaction monomer to prepare a resin prepolymer, thereby solving the problem of slow heat transfer in the resin prepolymerization stage, ensuring rapid transfer of reaction heat, and avoiding explosion polymerization and the production of low molecular weight by-products caused by local overheating of the reaction system; then, the resin prepolymer is subjected to solid phase melt polycondensation in combination with a continuous polycondensation reactor to increase the molecular weight of the resin, further making the synthesized resin have uniform molecular weight, high purity and good quality, meeting the application requirements of fiber-grade resin; and in terms of molecular structure design, during the polycondensation reaction, a modifier with flame retardant function is directly grafted onto the LCP resin molecular chain, and the four benzene rings on the side chain are connected to the molecular chain through P atoms, thereby optimizing the interaction force between the macromolecular chains, which is beneficial to the mechanical properties, temperature resistance and flame retardant properties of the product.

[0054] Example 1 The LCP fibers were prepared as follows: At room temperature, 138.12 g (1 mol) of p-hydroxybenzoic acid was dissolved in an appropriate amount of acetone to prepare a benzene ring-containing monomer solution; 263.5 g (1.4 mol) of 2-hydroxy-6-naphthoic acid was dissolved in an appropriate amount of ether to prepare a naphthalene ring-containing monomer solution; 214.22 g (1 mol) of 4,4'-dihydroxybenzophenone was dissolved in an appropriate amount of acetone to prepare a functional monomer solution; 0.62 g of thionyl chloride was dissolved in an appropriate amount of acetone to prepare a catalyst solution. The prepared solutions were pumped into the microchannel continuous flow reactor for esterification reaction, wherein the flow rate of the benzene ring-containing monomer solution was 10 mL / min, the flow rate of the naphthalene ring-containing monomer solution was 10 mL / min, the flow rate of the functional monomer solution was 10 mL / min, the flow rate of the catalyst solution was 0.1 mL / min, the esterification reaction temperature was 65°C, the reaction time was 30 min, the reaction liquid at the outlet of the microchannel continuous flow reactor was collected, and the reaction liquid was subjected to reduced pressure distillation to remove the reaction solvent, and the LCP resin prepolymer was obtained after drying. According to calculation, the molar mass ratio of the benzene ring-containing monomer, the naphthalene ring-containing monomer, and the functional monomer is 1:1.4:1.

[0055] The dried LCP resin prepolymer was added to a continuous polycondensation reactor, nitrogen was filled to deoxygenate, the temperature was raised to 180°C, 389g (1.8mol) of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was added, stirred for 3h, and then the temperature was raised to 270°C for polycondensation reaction. After 2h of reaction, LCP resin was obtained. The molar mass ratio of the flame retardant modifier to the functional monomer was calculated to be 1.8:1.

[0056] The LCP resin is added into the spinning equipment, and the spun fibers are obtained through melting, extrusion and drawing, wherein the melting temperature is 300°C and the drawing speed is 800m / min; the spun fibers are heat treated to obtain LCP fibers, wherein the heat treatment temperature is 260°C and the heat treatment time is 22h.

[0057] Example 2 The difference between this embodiment and embodiment 1 is that the amount of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide added is 324 g (1.5 mol). According to calculation, the molar mass ratio of the flame retardant modifier to the functional monomer is 1.5:1.

[0058] Example 3 The difference between this embodiment and embodiment 1 is that the amount of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide added is 518 g (2.4 mol). According to calculation, the molar mass ratio of the flame retardant modifier to the functional monomer is 2.4:1.

[0059] Example 4 The LCP fibers were prepared as follows: At room temperature, 138.12 g (1 mol) of p-hydroxybenzoic acid was dissolved in an appropriate amount of acetone to prepare a benzene ring-containing monomer solution; 225.8 g (1.2 mol) of 7-hydroxy-2-naphthoic acid was dissolved in an appropriate amount of ether to prepare a naphthalene ring-containing monomer solution; 235.6 g (1.1 mol) of 4,4'-dihydroxybenzophenone was dissolved in an appropriate amount of acetone to prepare a functional monomer solution; 0.90 g of thionyl chloride was dissolved in an appropriate amount of acetone to prepare a catalyst solution. The prepared solutions were pumped into the microchannel continuous flow reactor for esterification reaction, wherein the flow rate of the benzene ring-containing monomer solution was 12 mL / min, the flow rate of the naphthalene ring-containing monomer solution was 12 mL / min, the flow rate of the functional monomer solution was 12 mL / min, the flow rate of the catalyst solution was 0.15 mL / min, the esterification reaction temperature was 60°C, the reaction time was 45 min, the reaction liquid at the outlet of the microchannel continuous flow reactor was collected, and the reaction liquid was subjected to reduced pressure distillation to remove the reaction solvent, and the LCP resin prepolymer was obtained after drying. According to calculation, the molar mass ratio of the benzene ring-containing monomer, the naphthalene ring-containing monomer, and the functional monomer is 1:1.2:1.1.

[0060] The dried LCP resin prepolymer was added to a continuous polycondensation reactor, filled with nitrogen to deoxygenate, heated to 185°C, and 475g (2.2mol) of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was added. After stirring for 2.5 hours, the temperature was raised to 280°C for polycondensation reaction. After 1.5 hours of reaction, LCP resin was obtained. According to calculation, the molar mass ratio of flame retardant modifier to functional monomer is 2:1 The LCP resin is added into the spinning equipment, and the spun fibers are obtained through melting, extrusion and drawing, wherein the melting temperature is 310°C and the drawing speed is 900 m / min; the spun fibers are heat treated to obtain LCP fibers, wherein the heat treatment temperature is 270°C and the heat treatment time is 18 hours.

[0061] Example 5 The LCP fibers were prepared as follows: At room temperature, 166.12 g (1 mol) of terephthalic acid was dissolved in an appropriate amount of acetone to prepare a benzene ring-containing monomer solution; 160.2 g (1.2 mol) of 2,7-dihydroxynaphthalene was dissolved in an appropriate amount of ether to prepare a naphthalene ring-containing monomer solution; 278.5 g (1 mol) of 4,4'-dihydroxybenzophenone was dissolved in an appropriate amount of acetone to prepare a functional monomer solution; 1.21 g of trifluoromethanesulfonic acid was dissolved in an appropriate amount of acetone to prepare a catalyst solution. The prepared solutions were pumped into the microchannel continuous flow reactor for esterification reaction, wherein the flow rate of the benzene ring-containing monomer solution was 15 mL / min, the flow rate of the naphthalene ring-containing monomer solution was 15 mL / min, the flow rate of the functional monomer solution was 15 mL / min, the flow rate of the catalyst solution was 0.2 mL / min, the esterification reaction temperature was 55°C, the reaction time was 60 min, the reaction liquid at the outlet of the microchannel continuous flow reactor was collected, and the reaction liquid was subjected to reduced pressure distillation to remove the reaction solvent, and the LCP resin prepolymer was obtained after drying. According to calculation, the molar mass ratio of the benzene ring-containing monomer, the naphthalene ring-containing monomer, and the functional monomer is 1:1:1.3.

[0062] The dried LCP resin prepolymer was added to a continuous polycondensation reactor, filled with nitrogen to remove oxygen, heated to 190°C, and 617.8g (2.86mol) of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was added. After stirring for 2 hours, the temperature was raised to 290°C for polycondensation reaction. After 1 hour of reaction, LCP resin was obtained. According to calculation, the molar mass ratio of flame retardant modifier to functional monomer is 2.2:1 Add LCP resin to the spinning equipment, and obtain spun fibers through melting, extrusion and drawing, wherein the melting temperature is 320°C and the drawing speed is 1000m / min; heat-treat the spun fibers to obtain LCP fibers, wherein the heat treatment temperature is 280°C and the heat treatment time is 24h.

[0063] Comparative Example 1 The difference between this comparative example and Example 1 is that in the preparation process of the LCP resin prepolymer, the molar mass ratio of the benzene ring-containing monomer, the naphthalene ring-containing monomer and the functional monomer used is 1.5:1.9:0.

[0064] Comparative Example 2 The difference between this comparative example and Example 1 is that during the preparation of the LCP resin, no 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was added.

[0065] Comparative Example 3 138.12g (1 mol) of p-hydroxybenzoic acid, 263.5g (1.4 mol) of 2-hydroxy-6-naphthoic acid, 214.22g (1 mol) of 4,4'-dihydroxybenzophenone and 0.62g of thionyl chloride were put into a continuous polycondensation reactor, nitrogen was filled to deoxygenate and the temperature was raised to 65°C. After 30 minutes of reaction, the reaction was completed and the viscosity of the system did not increase significantly, indicating that insufficient prepolymer was generated during the reaction and the monomer was not fully reacted.

[0066] Since the prepolymerization effect of this comparative example is poor and subsequent spinning treatment is not possible, no subsequent experimental tests were performed.

[0067] Experimental example The mechanical properties, thermal stability and flame retardant properties of the LCP fibers prepared in Examples 1-5 and Comparative Examples 1-3 were tested, wherein the mechanical properties were tested for fiber breaking strength according to GB / T19975-2005 "Test Method for Tensile Properties of High-Reinforced Filaments". The thermal stability was tested for the thermal decomposition temperature of the fiber under nitrogen conditions according to the thermogravimetric analysis test method, wherein the heating rate was 20°C / min and the temperature range was 20-800°C. The flame retardant properties were tested for the limiting oxygen index (LOI) according to GB / T 5455-2014 "Textile Combustion Performance Test Oxygen Index Method", and the fiber long-term flame retardant test method (the fiber was placed in an oven at 150°C for aging for 1 month) was used to test the limiting oxygen index of the aged fiber. The test results are shown in Table 1.

[0068] Table 1 Test results of Examples 1-5 and Comparative Examples 1-3

[0069] From Table 1 we can see that: According to the test results of Examples 1-5, the breaking strength of the obtained LCP fiber is ≥20.6 cN / dtex, the thermal decomposition temperature is ≥503°C, the limiting oxygen index is ≥40.2%, and the limiting oxygen index after aging for one month is ≥39.8%, indicating that the LCP fiber prepared by the synthesis method of the present invention is excellent in mechanical properties, thermal stability and flame retardant properties.

[0070] Among them, compared with Example 1, the comprehensive performance of the fiber obtained in Example 2 is slightly reduced. The reason may be that the amount of flame retardant modifier used in Example 2 is less, and the amount of flame retardant groups and additional benzene ring structures introduced is reduced, so the mechanical properties, thermal stability, and flame retardant properties of the fiber are reduced, but the comprehensive performance is still relatively good.

[0071] In Example 3, the amount of flame retardant modifier used is relatively large and the limiting oxygen index is relatively high. However, due to the excessive amount of flame retardant modifier used, part of the flame retardant modifier is not chemically grafted on the LCP resin prepolymer but is in a physically blended state. The limiting oxygen index decreases relatively much after aging for one month, but still maintains a high level. Considering the comprehensive cost, there is no need to add too much flame retardant modifier.

[0072] By comparing the test results of Example 1 with those of Comparative Example 1, it can be seen that the comprehensive performance of the fiber obtained in Comparative Example 1 is significantly reduced. The reason may be that: Comparative Example 1 lacks 4,4'-dihydroxybenzophenone, and the flame retardant modifier cannot be grafted onto the resin segment. Therefore, the flame retardant modifier in Comparative Example 1 can only exist in the fiber through physical blending. Although the limiting oxygen index is still high before aging, the flame retardant modifier is easy to migrate and precipitate with the occurrence of aging, so the flame retardant performance after aging is significantly reduced. Compared with the case where the flame retardant modifier is grafted on the polymer main chain in Example 1, the mixed method of doping the flame retardant modifier is not conducive to the improvement of the mechanical properties of the fiber.

[0073] By comparing the test results of Example 1 with those of Comparative Example 2, it can be seen that the breaking strength, thermal decomposition temperature and limiting oxygen index of the fiber obtained in Comparative Example 2 are significantly reduced. The possible reasons are: no flame retardant modifier is added, there is no flame retardant group in the system, so the flame retardant performance of the fiber is deteriorated; at the same time, the lack of flame retardant modifier cannot introduce additional rigid benzene rings into the resin, and the interaction force between the macromolecular chains cannot be optimized, which leads to a decrease in the mechanical properties of the fiber.

[0074] The above implementation modes are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A LCP resin, characterized in that Its structural formula is as follows: Among them, X=30%-50%, Y=30%-50%, Z=20%-30%.

2. The LCP resin according to claim 1, characterized in that The synthetic raw materials of the LCP resin include LCP resin prepolymer and flame retardant modifier, and the structural formula of the LCP resin prepolymer is as follows: Among them, X=30%-50%, Y=30%-50%, Z=20%-30%; The raw materials for preparing the LCP resin prepolymer include benzene ring-containing monomers, naphthalene ring-containing monomers, functional monomers and catalysts; The molar mass ratio of the benzene ring-containing monomer, the naphthalene ring-containing monomer, and the functional monomer is 1:0.7-2:0.5-2; The flame retardant modifier is 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide; The molar mass ratio of the flame retardant modifier to the functional monomer is 1.5-2.4:

1.

3. The LCP resin according to claim 2, characterized in that The benzene ring-containing monomer includes at least one of p-hydroxybenzoic acid and terephthalic acid; The naphthalene ring-containing monomer includes at least one of 2-hydroxy-6-naphthoic acid, 7-hydroxy-2-naphthoic acid, and 2,7-dihydroxynaphthalene; The functional monomer includes 4,4'-dihydroxybenzophenone; The catalyst comprises at least one of thionyl chloride and trifluoromethanesulfonic acid; The molar mass ratio of the benzene ring-containing monomer, the naphthalene ring-containing monomer, and the functional monomer is 1:1-1.4:1-1.3; The molar mass ratio of the flame retardant modifier to the functional monomer is 1.8-2.2:

1.

4. A method for synthesizing LCP resin using a microchannel continuous flow reaction process, characterized in that: The method comprises the following steps: adding LCP resin prepolymer into a continuous polycondensation reaction kettle, adding a flame retardant modifier to carry out polycondensation reaction, so as to obtain LCP resin.

5. The method for synthesizing LCP resin using a microchannel continuous flow reaction process according to claim 4, characterized in that: The method comprises the following steps: adding LCP resin prepolymer into a continuous polycondensation reaction kettle, filling with nitrogen to deoxygenate, and heating to 180-190 DEG C; adding a flame retardant modifier, stirring and reacting for 2-3 hours, and heating to 270-290 DEG C to react for 1-2 hours to obtain LCP resin.

6. The method for synthesizing LCP resin using a microchannel continuous flow reaction process according to claim 4, characterized in that: The preparation steps of the LCP resin prepolymer include: (1) dissolving a benzene ring-containing monomer, a naphthalene ring-containing monomer, a functional monomer and a catalyst in an organic solution to obtain a benzene ring-containing monomer solution, a naphthalene ring-containing monomer solution, a functional monomer solution and a catalyst solution; (2) The benzene ring-containing monomer solution, the naphthalene ring-containing monomer solution, the functional monomer solution and the catalyst solution are pumped into a microchannel continuous flow reactor respectively to carry out an esterification reaction. After the reaction is completed, an LCP resin prepolymer is obtained through post-treatment.

7. The method for synthesizing LCP resin using a microchannel continuous flow reaction process according to claim 6, characterized in that: In step (1), the organic solvent includes at least one of acetone, ether, and alcohol solvents; In step (2), the temperature of the esterification reaction is 50-70° C., and the reaction time is 30-60 min.

8. The method for synthesizing LCP resin using a microchannel continuous flow reaction process according to claim 6, characterized in that: In step (2), the microchannel continuous flow reactor is a tubular structure, and the hydraulic diameter of the channel is 10-20 mm; the flow rate of the benzene ring-containing monomer solution is 10-15 ml / min; the flow rate of the naphthalene ring-containing monomer solution is 10-15 ml / min; the flow rate of the functional monomer solution is 10-15 ml / min; and the flow rate of the catalyst solution is 0.1-0.2 ml / min.

9. A method for synthesizing LCP fiber, characterized in that: The steps include: (1) Adding the LCP resin described in any one of claims 1 to 3 or the LCP resin prepared by the method of claims 4 to 8 into a spinning device, and obtaining spun fibers after melting, extrusion and drawing; wherein the melting temperature is 300-320°C, and the drawing speed is 800-1000 m / min; (2) heat treating the spun fibers to obtain LCP fibers; wherein the heat treatment temperature is 260-280° C. and the time is 12-24 hours.

10. An LCP fiber, characterized in that: The product is prepared by the synthesis method described in claim 9.

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