LCP resin synthesized by micro-channel continuous flow reaction process, LCP fiber and synthesis method thereof

Abstract

The application discloses a kind of LCP resin, LCP fiber and synthesis method thereof synthesized by microchannel continuous flow reaction process, wherein, LCP resin is introduced into flame-retardant modifier to LCP prepolymer, i.e., LCP resin prepolymer is added to continuous polycondensation reactor, and flame-retardant modifier is added to carry out polycondensation reaction to obtain LCP resin. Four benzene rings in the structure of flame-retardant modifier are chemically connected by P atom and molecular chain in LCP resin, which can optimize the interaction force between molecular chains, and further effectively improve the mechanical properties and flame-retardant properties of the product.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of liquid crystal polymer, in particular to a LCP resin and LCP fiber synthesized by micro-channel continuous flow reaction process and a synthesis method thereof. BACKGROUND

[0002] Liquid crystal polymer (LCP) is a special polymer material, which has high strength, high modulus, excellent forming and processing performance, outstanding heat resistance, low water absorption, low dielectric constant and dielectric loss factor, etc. It is widely used in electronic and electrical appliances, 5G communication, consumer electronics, automotive parts, aerospace, national defense and military industry, etc. At present, the polymerization method of LCP resin is mainly melt polycondensation, but most of the existing melt polycondensation is carried out in a kettle reactor, which is difficult to realize continuous production, and the synthesis process will produce more by-products due to poor temperature control, which seriously affects the purity and quality of the product. SUMMARY

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

[0004] In order to achieve the above purpose, the present application provides a LCP resin, whose structural formula is as follows:

[0005]

[0006] Among them, X=30%-50%, Y=30%-50%, Z=20%-30%.

[0007] Further, the synthesis raw material of LCP resin includes LCP resin prepolymer and flame-retardant modifier.

[0008] Further, the flame-retardant modifier is 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide.

[0009] Further, the structural formula of LCP resin prepolymer is as follows:

[0010]

[0011] Among them, X=30%-50%, Y=30%-50%, Z=20%-30%.

[0012] Further, the preparation raw material includes benzene ring containing monomer, naphthalene ring containing monomer, functional monomer and catalyst.

[0013] Further, the molar mass ratio of flame-retardant modifier to functional monomer is 1.5-2.4:1.

[0014] Preferably, the molar mass ratio of the flame-retardant modifier to the functional monomer is 1.8-2.2:1.

[0015] Further, the benzene ring-containing monomer includes at least one of p-hydroxybenzoic acid, p-phenylenediamine.

[0016] Further, the naphthalene ring-containing monomer includes at least one of 2-hydroxy-6-naphthoic acid, 7-hydroxy-2-naphthoic acid, and 2,7-dihydroxynaphthalene.

[0017] Further, the functional monomer includes 4,4'-dihydroxybenzophenone.

[0018] Further, the catalyst includes at least one of sulfurous acid chloride and trifluoromethanesulfonic acid.

[0019] Further, the catalyst is used in an amount of 0.1%-0.2% of the total mass of the benzene ring-containing monomer, the naphthalene ring-containing monomer, and the functional monomer.

[0020] Further, 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.

[0021] 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.

[0022] The LCP resin of the present application has a modification agent with a flame-retardant function grafted to the molecular chain of the LCP resin, so as to avoid the problem of migration and precipitation of the flame-retardant modifier in the traditional physical blending modification method, which affects the mechanical properties and flame-retardant properties of the resin. The four benzene rings on the side chain are connected to the molecular chain through P atoms, so that the four benzene rings on the side chain are arranged non-coplanarly 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.

[0023] The present application also provides a method for synthesizing the LCP resin by using a micro-channel continuous flow reaction process, which includes the following steps: adding an LCP resin prepolymer into a continuous polycondensation reactor, adding a flame-retardant modifier for polycondensation reaction, so as to obtain the LCP resin.

[0024] Preferably, the method for synthesizing the LCP resin by using a micro-channel continuous flow reaction process includes the following steps: adding an LCP resin prepolymer into a continuous polycondensation reactor, removing oxygen by nitrogen, and heating to 180-190℃; adding a flame-retardant modifier, stirring for 2-3h, and then heating to 270-290℃ for 1-2h, so as to obtain the LCP resin.

[0025] Further, the preparation steps of the LCP resin prepolymer include:

[0026] (1) dissolving the benzene ring-containing monomer, the naphthalene ring-containing monomer, the functional monomer and the catalyst in an organic solvent to obtain a benzene ring-containing monomer solution, a naphthalene ring-containing monomer solution, a functional monomer solution and a catalyst solution;

[0027] (2) pumping the benzene ring-containing monomer solution, the naphthalene ring-containing monomer solution, the functional monomer solution and the catalyst solution into a micro-channel continuous flow reactor respectively to perform esterification reaction, and after the reaction is completed, obtaining the LCP resin prepolymer through post-treatment.

[0028] Further, in step (1), the organic solvent includes at least one of acetone, diethyl ether and alcohol solvent.

[0029] Further, in step (2), the esterification reaction is performed at a temperature of 50-70℃ for 30-60 min.

[0030] Further, in step (2), the micro-channel continuous flow reactor is in a tubular structure, the channel hydraulic diameter 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.

[0031] In step (2), the solution polymerization reaction is performed in the micro-channel continuous flow reactor, which can solve the difficulty of slow heat transfer speed in the LCP resin prepolymerization stage, ensure the rapid transfer of reaction heat to prevent the formation of low molecular weight by-products caused by local overheating of the reaction system, and further ensure good molecular dispersion and stable and controllable intrinsic viscosity of the final LCP resin.

[0032] The synthesis method of the present application can better combine the advantages of solution polymerization and melt polymerization, first performing solution polymerization of the benzene ring-containing monomer solution, the naphthalene ring-containing monomer solution and the functional monomer solution in the micro-channel continuous flow reactor to obtain LCP resin prepolymer with uniform molecular weight, and then performing solid-phase melt polycondensation of the LCP resin prepolymer in a continuous polycondensation reactor to greatly increase the molecular weight of the LCP resin, so that the finally synthesized LCP resin has uniform molecular weight and high purity, meeting the application requirements of fiber-grade resin; and due to the addition of the functional monomer, the modifier with flame-retardant function can be directly grafted onto the LCP resin molecular chain during the melt polycondensation, so as to avoid the problems of migration and precipitation of the flame-retardant modifier caused by physical blending modification in the prior art, affecting the mechanical properties and flame-retardant properties of the LCP resin.

[0033] Compared with the amplification effect of the traditional reactor, the synthesis method for preparing the fiber-grade LCP resin of the present application does not need amplification effect, which is good for industrialized large-scale continuous production.

[0034] The application utilizes the above LCP resin as raw material to prepare LCP fiber, a synthesis method thereof, comprising the following steps:

[0035] (1) adding LCP resin into a spinning device, obtaining a primary fiber after melting, extruding and drawing, wherein the melting temperature is 300-320 DEG C, and the drawing speed is 800-1000 m / min;

[0036] (2) heat treating the primary fiber to obtain LCP fiber, wherein the heat treatment temperature is 260-280 DEG C, and the time is 12-24 h.

[0037] The application combines the advantages of solution polymerization and melt polymerization when synthesizing LCP resin by using micro-channel continuous flow reaction process, improves the synthesis quality of LCP resin, and further effectively improves the synthesis quality of LCP fiber. DETAILED DESCRIPTION

[0038] The preferred embodiments of the application are described in detail below to make the advantages and features of the application more easily understood by those skilled in the art, so as to make the protection scope of the application more clearly defined. It should be noted that the following embodiments are for better understanding of the application and do not limit the content and protection scope of the application, and any person who obtains any product same or similar to the application under the inspiration of the application or by combining the application with other prior art features falls within the protection scope of the application.

[0039] It should be noted that in the description of the specification, the description of the terms "one embodiment", "some embodiments", "exemplary embodiment", "example", "specific example" 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 application. In the specification, the exemplary description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

[0040] In addition, the specific experimental steps or conditions not mentioned in the embodiments can be performed according to the conventional experimental steps described in the literature in the art. The numerical range shown by "-" in the embodiments indicates a range including the minimum value and maximum value recorded before and after "-" as minimum value and maximum value. The reagents or instruments not mentioned by the manufacturer are conventional reagent products that can be obtained by market purchase.

[0041] The application provides a method for synthesizing LCP resin by using micro-channel continuous flow reaction process, comprising the following steps:

[0042] (1) respectively prepare a benzene ring containing monomer solution, a naphthalene ring containing monomer solution, a functional monomer solution and a catalyst solution. Specifically, at room temperature, the benzene ring containing monomer, the naphthalene ring containing monomer, the functional monomer and the catalyst are respectively dissolved in an organic solvent to prepare the benzene ring containing monomer solution, the naphthalene ring containing monomer solution, the functional monomer solution and the catalyst solution;

[0043] In some embodiments, the benzene ring containing monomer includes at least one of p-hydroxybenzoic acid and p-terephthalic acid.

[0044] 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.

[0045] In some embodiments, the functional monomer includes 4,4'-dihydroxybenzophenone.

[0046] In some embodiments, the catalyst includes at least one of thionyl chloride and triflic acid.

[0047] In some embodiments, the organic solvent includes at least one of acetone, diethyl ether and an alcohol solvent.

[0048] (2) The benzene ring containing monomer solution, the naphthalene ring containing monomer solution, the functional monomer solution and the catalyst solution are respectively pumped into a microchannel continuous flow reactor to perform an esterification reaction. After the reaction is completed, an LCP resin prepolymer is obtained through post-processing, and the structural formula is as follows:

[0049]

[0050] Wherein, X=30%-50%, Y=30%-50%, Z=20%-30%;

[0051] 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.

[0052] 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.

[0053] In some embodiments, the amount of the catalyst is 0.1%-0.2% of the total mass of the benzene ring containing monomer, the naphthalene ring containing monomer and the functional monomer participating in the esterification reaction.

[0054] In some embodiments, in step (2), the micro-channel continuous flow reactor is a tubular structure, the channel hydraulic diameter 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.

[0055] In some embodiments, the esterification reaction temperature is 50-70℃, and the reaction time is 30-60 min. The post-treatment includes vacuum distillation of the reaction solution to remove the reaction solvent, and the LCP resin prepolymer is obtained after drying.

[0056] (3) The LCP resin prepolymer is added to a continuous polycondensation reactor, and a flame-retardant modifier is added for polycondensation reaction to obtain an LCP resin, which has the following structural formula:

[0057]

[0058] In some embodiments, X=30%-50%, Y=30%-50%, and Z=20%-30%.

[0059] In some embodiments, step (3) specifically includes adding the LCP resin prepolymer to a continuous polycondensation reactor, purging oxygen with nitrogen and heating to 180-190℃; adding the flame-retardant modifier, stirring for 2-3 h, and then heating to 270-290℃ for 1-2 h to obtain the LCP resin.

[0060] In some embodiments, the flame-retardant modifier is 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide.

[0061] In some embodiments, the molar mass ratio of the flame-retardant modifier to the functional monomer is 1.5-2.4:1.

[0062] In some embodiments, the molar mass ratio of the flame-retardant modifier to the functional monomer is 1.8-2.2:1.

[0063] A method for preparing an LCP fiber using the above LCP resin includes the following steps:

[0064] (1) The above LCP resin is added to a spinning device, and after melting, extrusion and drawing, a nascent fiber is obtained; wherein the melting temperature is 300-320℃, and the drawing speed is 800-1000 m / min;

[0065] (2) The nascent fiber is heat-treated to obtain an LCP fiber; wherein the heat treatment temperature is 260-280℃, and the time is 12-24 h.

[0066] In the synthesis of the LCP resin of the present embodiment, the solution polymerization of each reaction monomer is carried out in a micro-channel continuous flow reactor to prepare a resin prepolymer, thereby solving the problem of slow heat transfer in the prepolymerization stage of the resin, ensuring rapid transfer of reaction heat, and avoiding the generation 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 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, and meeting the application requirements of fiber-grade resin; and in the molecular structure design, the modifier with flame-retardant function is directly grafted onto the molecular chain of the LCP resin during the polycondensation reaction, 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 and being beneficial to the mechanical properties, temperature resistance and flame retardance of the product.

[0067] Example 1

[0068] The LCP fiber is prepared according to the following steps:

[0069] At room temperature, 138.12 g (1 mol) of p-hydroxybenzoic acid is 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 is dissolved in an appropriate amount of diethyl ether to prepare a naphthalene ring-containing monomer solution; 214.22 g (1 mol) of 4,4'-dihydroxybenzophenone is dissolved in an appropriate amount of acetone to prepare a functional monomer solution; and 0.62 g of sulfoxonium chloride is dissolved in an appropriate amount of acetone to prepare a catalyst solution. The above prepared solutions are respectively pumped into a micro-channel continuous flow reactor to carry out esterification reaction, wherein the flow rate of the benzene ring-containing monomer solution is 10 mL / min, the flow rate of the naphthalene ring-containing monomer solution is 10 mL / min, the flow rate of the functional monomer solution is 10 mL / min, and the flow rate of the catalyst solution is 0.1 mL / min, the esterification reaction temperature is 65°C, the reaction time is 30 min, the reaction liquid at the outlet end of the micro-channel continuous flow reactor is collected, and the reaction liquid is subjected to vacuum distillation to remove the reaction solvent, and after drying, the LCP resin prepolymer is obtained. It is calculated that the molar mass ratio of the benzene ring-containing monomer, the naphthalene ring-containing monomer and the functional monomer is 1:1.4:1.

[0070] The dried LCP resin prepolymer is added to a continuous polycondensation reactor, nitrogen is introduced to remove oxygen, the temperature is raised to 180°C, 389 g (1.8 mol) of 9,10-dihydro-9-oxa-10-phospha-phenanthrene-10-oxide is added, and after stirring for 3 h, the temperature is raised to 270°C for polycondensation reaction, and after 2 h of reaction, the LCP resin is obtained. It is calculated that the molar mass ratio of the flame-retardant modifier and the functional monomer is 1.8:1.

[0071] The LCP resin is added to a spinning device, melted, extruded and drawn to obtain a nascent fiber, wherein the melting temperature is 300°C and the drawing speed is 800 m / min; the nascent fiber is heat treated to obtain the LCP fiber, wherein the heat treatment temperature is 260°C and the heat treatment time is 22 h.

[0072] Example 2

[0073] The difference between this example and Example 1 is that the amount of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 324 g (1.5 mol). The molar mass ratio of the flame-retardant modifier to the functional monomer is calculated to be 1.5:1.

[0074] Example 3

[0075] The difference between this example and Example 1 is that the amount of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 518 g (2.4 mol). The molar mass ratio of the flame-retardant modifier to the functional monomer is calculated to be 2.4:1.

[0076] Example 4

[0077] The LCP fiber is prepared according to the following steps:

[0078] At room temperature, 138.12 g (1 mol) of p-hydroxybenzoic acid is dissolved in an appropriate amount of acetone to prepare a benzene ring monomer solution; 225.8 g (1.2 mol) of 7-hydroxy-2-naphthoic acid is dissolved in an appropriate amount of diethyl ether to prepare a naphthalene ring monomer solution; 235.6 g (1.1 mol) of 4,4'-dihydroxybenzophenone is dissolved in an appropriate amount of acetone to prepare a functional monomer solution; and 0.90 g of sulfoxonium chloride is dissolved in an appropriate amount of acetone to prepare a catalyst solution. The above prepared solutions are respectively pumped into a micro-channel continuous flow reactor to perform esterification, wherein the flow rate of the benzene ring monomer solution is 12 mL / min, the flow rate of the naphthalene ring monomer solution is 12 mL / min, the flow rate of the functional monomer solution is 12 mL / min, and the flow rate of the catalyst solution is 0.15 mL / min; the esterification temperature is 60°C, the reaction time is 45 min, the reaction liquid at the outlet end of the micro-channel continuous flow reactor is collected, and the reaction liquid is subjected to vacuum distillation to remove the reaction solvent, and after drying, an LCP resin prepolymer is obtained. The molar mass ratio of the benzene ring monomer, the naphthalene ring monomer and the functional monomer is calculated to be 1:1.2:1.1.

[0079] The dried LCP resin prepolymer is added into a continuous polycondensation reactor, oxygen is removed by nitrogen, and the temperature is raised to 185°C. 475 g (2.2 mol) of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is added, and the reaction is stirred for 2.5 h. The temperature is then raised to 280°C, and the polycondensation reaction is carried out. After 1.5 h of reaction, the LCP resin is obtained. The molar mass ratio of the flame-retardant modifier to the functional monomer is 2:1.

[0080] The LCP resin is added into a spinning device, melted, extruded, and drawn to obtain a nascent fiber. The melting temperature is 310°C, and the drawing speed is 900 m / min. The nascent fiber is heat treated to obtain the LCP fiber. The heat treatment temperature is 270°C, and the heat treatment time is 18 h.

[0081] Example 5

[0082] The LCP fiber is prepared as follows:

[0083] At room temperature, 166.12 g (1 mol) of terephthalic acid is 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 is dissolved in an appropriate amount of diethyl ether to prepare a naphthalene ring-containing monomer solution. 278.5 g (1 mol) of 4,4'-dihydroxybenzophenone is dissolved in an appropriate amount of acetone to prepare a functional monomer solution. 1.21 g of triflic acid is dissolved in an appropriate amount of acetone to prepare a catalyst solution. The prepared solutions are pumped into a microchannel continuous flow reactor, and esterification is carried out. The flow rate of the benzene ring-containing monomer solution is 15 mL / min, the flow rate of the naphthalene ring-containing monomer solution is 15 mL / min, the flow rate of the functional monomer solution is 15 mL / min, and the flow rate of the catalyst solution is 0.2 mL / min. The esterification temperature is 55°C, and the reaction time is 60 min. The reaction liquid at the outlet of the microchannel continuous flow reactor is collected, and the reaction solvent is removed by vacuum distillation. After drying, the LCP resin prepolymer is obtained. The molar mass ratio of the benzene ring-containing monomer, the naphthalene ring-containing monomer, and the functional monomer is 1:1:1.3.

[0084] The dried LCP resin prepolymer is added into a continuous polycondensation reactor, oxygen is removed by nitrogen, and the temperature is raised to 190°C. 617.8 g (2.86 mol) of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is added, and the reaction is stirred for 2 h. The temperature is then raised to 290°C, and the polycondensation reaction is carried out. After 1 h of reaction, the LCP resin is obtained. The molar mass ratio of the flame-retardant modifier to the functional monomer is 2.2:1.

[0085] The LCP resin is added to a spinning device, and after melting, extrusion and drawing, a nascent fiber is obtained, wherein the melting temperature is 320℃, and the drawing speed is 1000 m / min; the nascent fiber is heat treated to obtain the LCP fiber, wherein the heat treatment temperature is 280℃, and the heat treatment time is 24 h.

[0086] Comparative Example 1

[0087] The difference between this comparative example and Example 1 is that the molar mass ratio of the benzene ring-containing monomer, the naphthalene ring-containing monomer and the functional monomer used in the preparation of the LCP resin prepolymer is 1.5:1.9:0.

[0088] Comparative Example 2

[0089] The difference between this comparative example and Example 1 is that 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is not added in the preparation of the LCP resin.

[0090] Comparative Example 3

[0091] Put 138.12 g (1 mol) of p-hydroxybenzoic acid, 263.5 g (1.4 mol) of 2-hydroxy-6-naphthoic acid, 214.22 g (1 mol) of 4,4'-dihydroxybenzophenone, and 0.62 g of sulfurous chloride into a continuous polycondensation reactor, deoxygenate by nitrogen, and heat to 65℃. After 30 min of reaction, the reaction is completed, and the system viscosity does not increase significantly, indicating that sufficient prepolymer is not generated during the reaction, and the monomers are not fully reacted.

[0092] Since the pre-polymerization effect of this comparative example is poor, subsequent spinning treatment cannot be carried out, and therefore, subsequent experimental tests are not carried out.

[0093] Experimental Example

[0094] The LCP fibers prepared in Examples 1-5 and Comparative Examples 1-3 are tested for mechanical properties, thermal stability and flame retardant properties, wherein the fiber breaking strength is tested according to the standard GB / T 19975-2005 "High-strength fiber filament tensile property test method". The thermal decomposition temperature of the fiber is tested under nitrogen according to the thermal gravimetric analysis test method, wherein the heating rate is 20℃ / min, and the temperature range is 20-800℃. The limiting oxygen index (LOI) is determined according to the standard GB / T 5455-2014 "Textile combustion property test oxygen index method", and the limiting oxygen index of the fiber after aging is tested by the long-term flame retardant property determination method (the fiber is placed in an oven at 150℃ for 1 month). The test results are shown in Table 1.

[0095] Table 1 Test results of Examples 1-5 and Comparative Examples 1-3

[0096]

[0097] As can be seen from Table 1:

[0098] 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 ℃, the limiting oxygen index is ≥40.2 %, and the limiting oxygen index after aging for 1 month is ≥39.8 %; it is shown that the LCP fiber prepared by the synthetic method of the application is excellent in mechanical properties, thermal stability and flame retardant properties.

[0099] Among them, compared with Example 1, the comprehensive performance of the fiber obtained in Example 2 decreases slightly, which may be due to: the amount of flame retardant modifier in Example 2 is less, the amount of flame retardant groups and additional benzene ring structure introduced is less, so the mechanical properties, thermal stability and flame retardant properties of the fiber are decreased, but the comprehensive performance is still relatively good.

[0100] In Example 3, the amount of flame retardant modifier is more, and the limiting oxygen index is higher, but due to the excessive amount of flame retardant modifier, part of the flame retardant modifier is not chemically grafted on the LCP resin prepolymer but in a physical blending state, the limiting oxygen index after aging for 1 month decreases relatively more, but still maintains a high level, considering the comprehensive cost, it is not necessary to add too much flame retardant modifier.

[0101] According to the test results of Comparative Example 1 and Comparative Example 1, the comprehensive performance of the fiber obtained in Comparative Example 1 decreases obviously, which may be due to: 4,4'-dihydroxybenzophenone is lacking in Comparative Example 1, 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 by physical blending, although the limiting oxygen index before aging is still high, but with the occurrence of aging, the flame retardant modifier is easy to migrate and precipitate, thus the flame retardant performance after aging decreases obviously, and compared with the case that the flame retardant modifier is grafted on the polymer main chain in Example 1, the mixed way of doping the flame retardant modifier is not conducive to the improvement of the mechanical properties of the fiber.

[0102] According to the test results of Comparative Example 1 and Comparative Example 2, the breaking strength, thermal decomposition temperature and limiting oxygen index of the fiber obtained in Comparative Example 2 decrease obviously, which may be due to: no flame retardant modifier is added, and there is no flame retardant group in the system, so the flame retardant performance of the fiber is deteriorated; at the same time, due to the absence of the flame retardant modifier, the additional rigid benzene ring cannot be introduced into the resin, and the interaction force between the macromolecular chains cannot be optimized, thus the mechanical properties of the fiber are decreased.

[0103] The above embodiments are only for illustrating the technical concept and characteristics of the present application, and the purpose is to enable those skilled in the art to understand the content of the present application and implement it, and cannot limit the protection scope of the present application, and any equivalent changes or modifications made according to the spirit and essence of the present application shall be covered within the protection scope of the present application.

Claims

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

2. The LCP resin according to claim 1, characterized in that, The raw materials for synthesizing the LCP resin include an LCP resin prepolymer and a flame retardant modifier. The structural formula of the LCP resin prepolymer is as follows: Where X = 30%-50%, Y = 30%-50%, Z = 20%-30%; The raw materials for preparing the LCP resin prepolymer include monomers containing benzene rings, monomers containing naphthalene rings, 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 ratio of the flame retardant modifier to the functional monomer is 1.5-2.4:

1. The functional monomer is 4,4'-dihydroxybenzophenone.

3. The LCP resin according to claim 2, characterized in that, The benzene ring-containing monomer includes p-hydroxybenzoic acid; The naphthalene-containing monomer is 2-hydroxy-6-naphthoic acid; The catalyst includes 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 the LCP resin according to any one of claims 1-3 using a microchannel continuous flow reaction process, characterized in that, The process includes the following steps: adding LCP resin prepolymer to a continuous polycondensation reactor, adding a flame retardant modifier to carry out the polycondensation reaction, and obtaining LCP resin.

5. The method according to claim 4, characterized in that, The process includes the following steps: adding LCP resin prepolymer to a continuous polycondensation reactor, purging with nitrogen to remove oxygen, and heating to 180-190℃; adding flame retardant modifier, stirring and reacting for 2-3 hours, and then heating to 270-290℃ and reacting for 1-2 hours to obtain LCP resin.

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

7. The method according to claim 6, characterized in that, In step (1), the organic solvent includes at least one of acetone, diethyl ether, and alcohol solvents; In step (2), the esterification reaction is carried out at a temperature of 50-70°C for 30-60 minutes.

8. The method according to claim 6, characterized in that, In step (2), the microchannel continuous flow reactor is a tubular structure with a channel hydraulic diameter of 10-20 mm; the flow rate of the benzene ring monomer solution is 10-15 ml / min; the flow rate of the naphthalene ring 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 fibers, characterized in that, Includes the following steps: (1) The LCP resin according to any one of claims 1-3 or the LCP resin prepared by the method according to any one of claims 4-8 is added to a spinning device, and nascent fibers are obtained after melting, extrusion and stretching; wherein the melting temperature is 300-320℃ and the stretching speed is 800-1000m / min; (2) The nascent fibers are heat-treated to obtain LCP fibers; wherein the heat treatment temperature is 260-280℃ and the time is 12-24h.

10. An LCP fiber, characterized in that, It was prepared by the synthesis method described in claim 9.

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