A method for preparing a liquid crystal polymer composite material

Abstract

A method for preparing a liquid crystal polymer composite material relates to the technical field of special engineering plastics. The purpose of the present invention is to solve the problems of the current liquid crystal polymer having high dielectric constant and dielectric loss and poor mechanical properties. The present invention modifies the liquid crystal polymer resin by zeolite molecular sieve so that the composite material has a lower dielectric constant, and at the same time uses a coupling agent containing a specific group to increase the compatibility of the liquid crystal polymer resin and the zeolite molecular sieve, so that the interface between the two is greatly improved. Even if a large proportion of zeolite molecular sieve filler is added, the liquid crystal polymer composite material still has good mechanical properties. The present invention can obtain a method for preparing a liquid crystal polymer composite material.

Description

Technical Field

[0001] The invention relates to the technical field of special engineering plastics, and in particular to a method for preparing a liquid crystal polymer composite material. Background Art

[0002] Liquid crystal polymer (LCP) is a rigid polymer that has both liquid fluidity and crystal anisotropy above the melting temperature or glass transition temperature. The rigid chain structure and orderly arrangement of molecules make LCP have excellent physical and mechanical comprehensive properties, and it has been widely used in aerospace, electrical and electronic, and automotive industries. With the research of 5G electronic communication technology, in order to reduce transmission delay, maintain high signal transmission rate, and reduce energy loss and signal distortion during modulation, higher requirements are placed on the dielectric properties of materials. For example, for high-speed substrates with medium transmission loss, when the transmission rate is higher than 10Gbps, the dielectric loss factor of the material is required to be 0.01-0.02, while for high-frequency substrates for microwave / millimeter wave applications, the dielectric loss factor is required to be ≦0.005 and the data transmission rate is 56Gbps. The common liquid crystal polymer dielectric constant is about 3.4, and the dielectric loss factor is about 0.02, which is difficult to meet the requirements of the electronics industry for dielectric properties of materials in the 5G era.

[0003] At present, the commonly used methods to reduce the dielectric constant and dielectric loss of liquid crystal polymers are mainly: first, adding hollow glass microspheres, but this type of filler usually has poor mechanical properties, is difficult to use in large quantities, and often faces the problem of poor polymer-filler compatibility; second, by doping polytetrafluoroethylene and other fluorine-containing resins for blending, but in order to maintain the mechanical properties of the material at high temperatures, the amount of polytetrafluoroethylene added is usually not more than 5 parts by weight, and this method has limited effect on reducing the overall dielectric constant and dielectric loss of the resin. Therefore, in order to expand the application scope of liquid crystal polymer materials in the 5G field, it is urgent to develop new liquid crystal polymer materials with better comprehensive performance. Summary of the invention

[0004] The purpose of the present invention is to solve the problems of high dielectric constant and dielectric loss and poor mechanical properties of liquid crystal polymers, and to provide a method for preparing a liquid crystal polymer composite material.

[0005] A method for preparing a liquid crystal polymer composite material is carried out according to the following steps:

[0006] Step S1: mixing p-hydroxybenzoic acid, indole-2,6-dicarboxylic acid and tetra-tert-butyldiphenol with an acylating agent, acetic anhydride and a catalyst to obtain a mixture a;

[0007] The molar ratio of p-hydroxybenzoic acid, indole-2,6-dicarboxylic acid and tetra-tert-butylbiphenol is (64-80): (10-18): (10-18);

[0008] Step S2: subjecting the mixture a obtained in step S1 to a prepolymerization reaction to obtain a prepolymer;

[0009] Step S3: Under an inert gas atmosphere, subjecting the prepolymer obtained in step S2 to a solid phase polycondensation reaction to obtain a liquid crystal polymer resin;

[0010] Step S4: adding 15 to 40 parts by weight of zeolite molecular sieve to an ethanol solution, adding 1 to 5 parts by weight of a silane coupling agent KH560 after ultrasonic dispersion, and then stirring and reacting at a temperature of 60 to 70° C. for 3 to 5 hours, and then filtering and drying to obtain a mixture b;

[0011] Step S5: adding 100 parts by weight of the liquid crystal polymer resin obtained in step S3 and the mixture b obtained in step S4 into a twin-screw extruder, and extruding a strip to obtain a liquid crystal polymer strip composite material;

[0012] Step S6: The liquid crystal polymer strip composite material obtained in step S5 is fed into a pelletizer through an air-cooled conveyor belt for pelletizing to obtain a liquid crystal polymer composite material.

[0013] Principle of the present invention:

[0014] The liquid crystal polymer resin used in the liquid crystal polymer composite material of the present invention is polymerized by p-hydroxybenzoic acid, indole-2,6-dicarboxylic acid, and tetra-tert-butyl biphenol in a specific ratio. The three monomers cooperate with each other, so that the liquid crystal polymer resin has a lower dielectric loss factor, thereby giving the liquid crystal polymer composite material a lower dielectric loss factor; at the same time, in order to make it have a lower dielectric constant, the inventor uses zeolite molecular sieve to modify the liquid crystal polymer resin. On the one hand, the zeolite molecular sieve has a porous structure, and a large amount of air is stored in its pore structure. The air has an extremely low dielectric constant of about 1; on the other hand, the zeolite molecular sieve has a large adsorption surface and a high adsorption activity, which can adsorb the ionic impurities already in the liquid crystal polymer composite material and generated during the processing, further improving its dielectric properties. However, it was found in the research process that if the liquid crystal polymer resin and the zeolite molecular sieve are directly blended and modified, the mechanical properties of the obtained liquid crystal polymer composite material are greatly reduced, and the injection molded test piece has a stratification phenomenon. This shows that the liquid crystal polymer resin is not compatible with the zeolite molecular sieve, and the zeolite molecular sieve is unevenly dispersed in the resin and easily falls off. In order to improve the above situation, the inventor adds a silane coupling agent KH560, and the siloxy group in the KH560 coupling agent can react with the hydroxyl group on the surface of the zeolite molecular sieve by hydrolysis, and the epoxy group can react with the secondary amine group (introduced by indole-2,6-dicarboxylic acid) on the liquid crystal polymer resin segment, thereby improving the compatibility of the liquid crystal polymer resin with the zeolite molecular sieve and promoting the uniform dispersion of the zeolite molecular sieve in the liquid crystal polymer resin matrix. In addition, it may be due to the improvement of the interface bonding that the composite system bears a certain load when it is stressed, and locally resists strain in the surrounding resin matrix, which will not cause the mechanical properties of the composite material to be reduced as in direct blending. Therefore, the composite material obtained by the above scheme in the present invention still has good mechanical properties.

[0015] Beneficial effects of the present invention:

[0016] (1) The liquid crystal polymer resin of the present invention is polymerized by specific ratios of p-hydroxybenzoic acid, indole-2,6-dicarboxylic acid, and tetra-tert-butyldiphenol. The three monomers work together to make the liquid crystal polymer resin have a lower dielectric loss factor, thereby making the liquid crystal polymer composite material have a lower dielectric loss factor.

[0017] (2) The present invention modifies the liquid crystal polymer resin by using zeolite molecular sieve so that the composite material has a lower dielectric constant. At the same time, a coupling agent containing a specific group is used to increase the compatibility of the liquid crystal polymer resin and the zeolite molecular sieve, thereby greatly improving the interface between the two. Even if a large proportion of zeolite molecular sieve filler is added, the liquid crystal polymer composite material still has good mechanical properties.

[0018] The invention can obtain a method for preparing a liquid crystal polymer composite material. DETAILED DESCRIPTION

[0019] Specific implementation method 1: This implementation method is a method for preparing a liquid crystal polymer composite material, which is carried out according to the following steps:

[0020] Step S1: mixing p-hydroxybenzoic acid, indole-2,6-dicarboxylic acid and tetra-tert-butyldiphenol with an acylating agent, acetic anhydride and a catalyst to obtain a mixture a;

[0021] The molar ratio of p-hydroxybenzoic acid, indole-2,6-dicarboxylic acid and tetra-tert-butylbiphenol is (64-80): (10-18): (10-18);

[0022] Step S2: subjecting the mixture a obtained in step S1 to a prepolymerization reaction to obtain a prepolymer;

[0023] Step S3: Under an inert gas atmosphere, subjecting the prepolymer obtained in step S2 to a solid phase polycondensation reaction to obtain a liquid crystal polymer resin;

[0024] Step S4: adding 15 to 40 parts by weight of zeolite molecular sieve to an ethanol solution, adding 1 to 5 parts by weight of a silane coupling agent KH560 after ultrasonic dispersion, and then stirring and reacting at a temperature of 60 to 70° C. for 3 to 5 hours, and then filtering and drying to obtain a mixture b;

[0025] Step S5: adding 100 parts by weight of the liquid crystal polymer resin obtained in step S3 and the mixture b obtained in step S4 into a twin-screw extruder, and extruding a strip to obtain a liquid crystal polymer strip composite material;

[0026] Step S6: The liquid crystal polymer strip composite material obtained in step S5 is fed into a pelletizer through an air-cooled conveyor belt for pelletizing to obtain a liquid crystal polymer composite material.

[0027] Specific embodiment 2: The difference between this embodiment and specific embodiment 1 is that the amount of acetic anhydride added as the acylating agent in step S1 is 1.5 to 3.0 times the total molar number of hydroxyl groups in p-hydroxybenzoic acid, indole-2,6-dicarboxylic acid and tetra-tert-butylbiphenol.

[0028] The other steps are the same as those in the first specific implementation.

[0029] Specific implementation method three: The difference between this implementation method and specific implementation method one or two is that the amount of the catalyst added in step S1 is 0.006-0.01% of the total mass of p-hydroxybenzoic acid, indole-2,6-dicarboxylic acid and tetra-tert-butyldiphenol, and the catalyst is potassium acetate.

[0030] The other steps are the same as those in the first or second embodiment.

[0031] Specific embodiment 4: The difference between this embodiment and specific embodiments 1 to 3 is that the prepolymerization reaction described in step S2 is carried out according to the following steps: the mixture a is heated to 130-150°C and kept warm at 130-150°C for 1-3h; after the insulation is completed, the temperature is raised to 300-350°C, and the insulation is continued at 300-350°C for 2-4h; after the insulation is completed, it is crushed, sieved through a 30-mesh sieve, and then dried at 120-140°C for 1-2h to obtain a prepolymer.

[0032] The other steps are the same as those in Specific Embodiments 1 to 3.

[0033] Specific embodiment 5: The difference between this embodiment and specific embodiments 1 to 4 is that the solid phase polycondensation reaction in step S3 is carried out at a temperature of 300 to 350° C. for 12 to 24 hours.

[0034] The other steps are the same as those in Specific Embodiments 1 to 4.

[0035] Specific embodiment 6: The difference between this embodiment and specific embodiments 1 to 5 is that the volume ratio of the zeolite molecular sieve to the ethanol solution in step S4 is 1:(1.5-2.5).

[0036] The other steps are the same as those in Specific Embodiments 1 to 5.

[0037] Specific embodiment seven: The difference between this embodiment and specific embodiments one to six is ​​that the zeolite molecular sieve is one or more of ZSM-5, ZSM-11, ZSM-12 and ZSM-23 molecular sieves; the pore size of the zeolite molecular sieve is 0.42 to 0.59 nm, and the particle size is 0.5 to 0.8 μm.

[0038] The other steps are the same as those in Specific Embodiments 1 to 6.

[0039] Specific embodiment eight: This embodiment differs from specific embodiments one to seven in that: the concentration of the ethanol solution in step S4 is 95%.

[0040] The other steps are the same as those in Specific Embodiments 1 to 7.

[0041] Specific embodiment 9: The difference between this embodiment and specific embodiments 1 to 8 is that when 100 parts by weight of liquid crystal polymer resin and mixture b are added to the twin-screw extruder in step S5, 5 to 10 parts by weight of hollow glass microspheres and 1 to 4 parts by weight of one or both of polytetrafluoroethylene are added at the same time.

[0042] The other steps are the same as those in Specific Embodiments 1 to 8.

[0043] Specific embodiment ten: The present embodiment differs from specific embodiments one to nine in that: in step S5, the temperature of the twin-screw extruder is set to 290-370° C., and the screw speed is 200-300 r / min.

[0044] The other steps are the same as those in Specific Embodiments 1 to 9.

[0045] The following examples are used to verify the beneficial effects of the present invention:

[0046] Example 1: A method for preparing a liquid crystal polymer composite material, comprising the following steps:

[0047] Step S1: preparing liquid crystal polymer resin;

[0048] The mixture a is mixed with p-hydroxybenzoic acid, indole-2,6-dicarboxylic acid and tetra-tert-butylbiphenol, an acylating agent acetic anhydride and a catalyst potassium acetate to obtain a mixture a; the mixture a is heated to 130°C and kept at 130°C for 3 hours; the mixture is heated to 300°C after the heat preservation is completed and kept at 300°C for 4 hours; after the heat preservation is completed, the mixture is crushed, passed through a 30-mesh sieve, and dried at 120°C for 2 hours to obtain a prepolymer; the prepolymer is subjected to a solid phase polycondensation reaction at 300°C for 24 hours under an inert gas atmosphere to obtain a liquid crystal polymer resin;

[0049] The molar ratio of p-hydroxybenzoic acid, indole-2,6-dicarboxylic acid and tetra-tert-butylbiphenol is 68:16:16; the amount of acetic anhydride added as the acylating agent is 1.5 times the total molar number of hydroxyl groups in p-hydroxybenzoic acid, indole-2,6-dicarboxylic acid and tetra-tert-butylbiphenol; the amount of the catalyst added is 0.006% of the total mass of p-hydroxybenzoic acid, indole-2,6-dicarboxylic acid and tetra-tert-butylbiphenol;

[0050] Step S2: preparing a zeolite molecular sieve-coupling agent mixture;

[0051] 35 parts by weight of ZSM-5 molecular sieves were added to a 95% ethanol solution, and 4 parts by weight of an alkane coupling agent KH560 were added after ultrasonic dispersion, and then stirred at 60° C. for 5 hours, and then filtered and dried to obtain a mixture b;

[0052] The volume ratio of the ZSM-5 molecular sieve to the ethanol solution is 1:2, the pore size of the ZSM-5 molecular sieve is 0.42-0.59 nm, and the particle size is 0.5-0.8 μm;

[0053] Step S3: preparing liquid crystal polymer composite material;

[0054] 100 parts by weight of a liquid crystal polymer resin is fed into a twin-screw extruder from a main feed port, and a mixture b is fed into the twin-screw extruder from a side feed port, the temperatures of the temperature zones of the twin-screw extruder are controlled to be T1=290°C, T2=310°C, T3=320°C, T4=340°C, T5=350°C, T6=360°C, T7=350°C, T8=340°C and T9=320°C in sequence, and the screw speed is 300 r / min; strips are extruded to obtain a liquid crystal polymer strip composite material; the liquid crystal polymer strip composite material is fed into a pelletizer through an air-cooled conveyor belt for pelletizing to obtain a liquid crystal polymer composite material.

[0055] Embodiment 2: A method for preparing a liquid crystal polymer composite material is carried out according to the following steps:

[0056] Step S1: preparing liquid crystal polymer resin;

[0057] The mixture a is mixed with p-hydroxybenzoic acid, indole-2,6-dicarboxylic acid and tetra-tert-butylbiphenol, an acylating agent acetic anhydride and a catalyst potassium acetate to obtain a mixture a; the mixture a is heated to 135°C and kept at 135°C for 2 hours; after the heat preservation, the mixture is heated to 310°C and kept at 310°C for 4 hours; after the heat preservation, the mixture is crushed, passed through a 30-mesh sieve, and dried at 130°C for 2 hours to obtain a prepolymer; the prepolymer is subjected to a solid phase polycondensation reaction at 310°C for 20 hours under an inert gas atmosphere to obtain a liquid crystal polymer resin;

[0058] The molar ratio of p-hydroxybenzoic acid, indole-2,6-dicarboxylic acid and tetra-tert-butylbiphenol is 72:14:14; the amount of acetic anhydride added as the acylating agent is twice the total molar number of hydroxyl groups in p-hydroxybenzoic acid, indole-2,6-dicarboxylic acid and tetra-tert-butylbiphenol; the amount of the catalyst added is 0.007% of the total mass of p-hydroxybenzoic acid, indole-2,6-dicarboxylic acid and tetra-tert-butylbiphenol;

[0059] Step S2: preparing a zeolite molecular sieve-coupling agent mixture;

[0060] 15 parts by weight of ZSM-5 molecular sieves are added to a 95% ethanol solution, and after ultrasonic dispersion, 1 part by weight of an alkane coupling agent KH560 is added, and then stirred at 60° C. for 5 hours, and then filtered and dried to obtain a mixture b;

[0061] The volume ratio of the ZSM-5 molecular sieve to the ethanol solution is 1:1.5, the pore size of the ZSM-5 molecular sieve is 0.42-0.59 nm, and the particle size is 0.5-0.8 μm;

[0062] Step S3: preparing liquid crystal polymer composite material;

[0063] 100 parts by weight of a liquid crystal polymer resin is fed into a twin-screw extruder from a main feed port, and a mixture b is fed into the twin-screw extruder from a side feed port, the temperatures of various temperature zones of the twin-screw extruder are controlled to be T1=290°C, T2=320°C, T3=330°C, T4=350°C, T5=370°C, T6=360°C, T7=350°C, T8=330°C and T9=310°C, and the screw speed is 300 r / min; strips are extruded to obtain a liquid crystal polymer strip composite material; the liquid crystal polymer strip composite material is fed into a pelletizer through an air-cooled conveyor belt for pelletizing to obtain a liquid crystal polymer composite material.

[0064] Embodiment 3: A method for preparing a liquid crystal polymer composite material is carried out according to the following steps:

[0065] Step S1: preparing liquid crystal polymer resin;

[0066] The mixture a is mixed with p-hydroxybenzoic acid, indole-2,6-dicarboxylic acid and tetra-tert-butylbiphenol, an acylating agent acetic anhydride and a catalyst potassium acetate to obtain a mixture a; the mixture a is heated to 140°C and kept at 140°C for 2 hours; the mixture is heated to 320°C after the heat preservation is completed and kept at 320°C for 3 hours; after the heat preservation is completed, the mixture is crushed, passed through a 30-mesh sieve, and dried at 130°C for 1 hour to obtain a prepolymer; the prepolymer is subjected to a solid phase polycondensation reaction at 320°C for 18 hours under an inert gas atmosphere to obtain a liquid crystal polymer resin;

[0067] The molar ratio of p-hydroxybenzoic acid, indole-2,6-dicarboxylic acid and tetra-tert-butylbiphenol is 80:10:10; the amount of acetic anhydride added as the acylating agent is 2.3 times the total molar number of hydroxyl groups in p-hydroxybenzoic acid, indole-2,6-dicarboxylic acid and tetra-tert-butylbiphenol; the amount of the catalyst added is 0.008% of the total mass of p-hydroxybenzoic acid, indole-2,6-dicarboxylic acid and tetra-tert-butylbiphenol;

[0068] Step S2: preparing a zeolite molecular sieve-coupling agent mixture;

[0069] 40 parts by weight of ZSM-5 molecular sieves were added to a 95% ethanol solution, and 5 parts by weight of an alkane coupling agent KH560 were added after ultrasonic dispersion, and then stirred at 70° C. for 3 h, and then filtered and dried to obtain a mixture b;

[0070] The volume ratio of the ZSM-5 molecular sieve to the ethanol solution is 1:2.5, the pore size of the ZSM-5 molecular sieve is 0.42-0.59 nm, and the particle size is 0.5-0.8 μm;

[0071] Step S3: preparing liquid crystal polymer composite material;

[0072] 100 parts by weight of a liquid crystal polymer resin is fed into a twin-screw extruder from a main feed port, and a mixture b is fed into the twin-screw extruder from a side feed port, the temperatures of the temperature zones of the twin-screw extruder are controlled to be T1=300°C, T2=320°C, T3=340°C, T4=350°C, T5=360°C, T6=350°C, T7=340°C, T8=330°C and T9=320°C in sequence, and the screw speed is 300 r / min; strips are extruded to obtain a liquid crystal polymer strip composite material; the liquid crystal polymer strip composite material is fed into a pelletizer through an air-cooled conveyor belt for pelletizing to obtain a liquid crystal polymer composite material.

[0073] Example 4: A method for preparing a liquid crystal polymer composite material, comprising the following steps:

[0074] Step S1: preparing liquid crystal polymer resin;

[0075] The mixture a is mixed with p-hydroxybenzoic acid, indole-2,6-dicarboxylic acid and tetra-tert-butylbiphenol, an acylating agent acetic anhydride and a catalyst potassium acetate to obtain a mixture a; the mixture a is heated to 140°C and kept at 140°C for 1 hour; the mixture is heated to 340°C after the heat preservation is completed and kept at 340°C for 2 hours; after the heat preservation is completed, the mixture is crushed, passed through a 30-mesh sieve, and dried at 130°C for 1 hour to obtain a prepolymer; the prepolymer is subjected to a solid phase polycondensation reaction at 340°C for 15 hours under an inert gas atmosphere to obtain a liquid crystal polymer resin;

[0076] The molar ratio of p-hydroxybenzoic acid, indole-2,6-dicarboxylic acid and tetra-tert-butylbiphenol is 76:12:12; the amount of acetic anhydride added as the acylating agent is 2.5 times the total molar number of hydroxyl groups in p-hydroxybenzoic acid, indole-2,6-dicarboxylic acid and tetra-tert-butylbiphenol; the amount of the catalyst added is 0.009% of the total mass of p-hydroxybenzoic acid, indole-2,6-dicarboxylic acid and tetra-tert-butylbiphenol;

[0077] Step S2: preparing a zeolite molecular sieve-coupling agent mixture;

[0078] 30 parts by weight of ZSM-5 molecular sieves were added to a 95% ethanol solution, and 3 parts by weight of an alkane coupling agent KH560 were added after ultrasonic dispersion, and then stirred at 70° C. for 3 hours, and then filtered and dried to obtain a mixture b;

[0079] The volume ratio of the ZSM-5 molecular sieve to the ethanol solution is 1:2, the pore size of the ZSM-5 molecular sieve is 0.42-0.59 nm, and the particle size is 0.5-0.8 μm;

[0080] Step S3: preparing liquid crystal polymer composite material;

[0081] 100 parts by weight of a liquid crystal polymer resin is fed into a twin-screw extruder from a main feed port, and a mixture b is fed into the twin-screw extruder from a side feed port, the temperatures of the temperature zones of the twin-screw extruder are controlled to be T1=310°C, T2=320°C, T3=330°C, T4=340°C, T5=360°C, T6=350°C, T7=340°C, T8=330°C and T9=310°C, and the screw speed is 300 r / min; strips are extruded to obtain a liquid crystal polymer strip composite material; the liquid crystal polymer strip composite material is fed into a pelletizer through an air-cooled conveyor belt for pelletizing to obtain a liquid crystal polymer composite material.

[0082] Embodiment 5: A method for preparing a liquid crystal polymer composite material is carried out according to the following steps:

[0083] Step S1: preparing liquid crystal polymer resin;

[0084] The mixture a is mixed with p-hydroxybenzoic acid, indole-2,6-dicarboxylic acid and tetra-tert-butylbiphenol, an acylating agent acetic anhydride and a catalyst potassium acetate to obtain a mixture a; the mixture a is heated to 150°C and kept at 150°C for 1 hour; the mixture is heated to 350°C after the heat preservation is completed and kept at 350°C for 2 hours; after the heat preservation is completed, the mixture is crushed, passed through a 30-mesh sieve, and dried at 140°C for 2 hours to obtain a prepolymer; the prepolymer is subjected to a solid phase polycondensation reaction at 350°C for 12 hours under an inert gas atmosphere to obtain a liquid crystal polymer resin;

[0085] The molar ratio of p-hydroxybenzoic acid, indole-2,6-dicarboxylic acid and tetra-tert-butylbiphenol is 64:18:18; the amount of acetic anhydride added as the acylating agent is 3 times the total molar number of hydroxyl groups in p-hydroxybenzoic acid, indole-2,6-dicarboxylic acid and tetra-tert-butylbiphenol; the amount of the catalyst added is 0.01% of the total mass of p-hydroxybenzoic acid, indole-2,6-dicarboxylic acid and tetra-tert-butylbiphenol;

[0086] Step S2: preparing a zeolite molecular sieve-coupling agent mixture;

[0087] 20 parts by weight of ZSM-5 molecular sieves were added to a 95% ethanol solution, and 2 parts by weight of an alkane coupling agent KH560 were added after ultrasonic dispersion, and then stirred at 60° C. for 5 hours, and then filtered and dried to obtain a mixture b;

[0088] The volume ratio of the ZSM-5 molecular sieve to the ethanol solution is 1:1.5, the pore size of the ZSM-5 molecular sieve is 0.42-0.59 nm, and the particle size is 0.5-0.8 μm;

[0089] Step S3: preparing liquid crystal polymer composite material;

[0090] 100 parts by weight of a liquid crystal polymer resin is fed into a twin-screw extruder from a main feed port, and a mixture b is fed into the twin-screw extruder from a side feed port, and the temperatures of the temperature zones of the twin-screw extruder are controlled to be T1=300°C, T2=320°C, T3=340°C, T4=350°C, T5=370°C, T6=360°C, T7=350°C, T8=340°C and T9=320°C in sequence, and the screw speed is 300 r / min; extruding strips to obtain a liquid crystal polymer strip composite material; and passing the liquid crystal polymer strip composite material into a pelletizer through an air-cooled conveyor belt for pelletizing to obtain a liquid crystal polymer composite material.

[0091] Embodiment 6:

[0092] The difference between this embodiment and embodiment 1 is that during the preparation of the liquid crystal polymer composite material, the material introduced from the side feed port includes, in addition to the mixture of zeolite molecular sieve and coupling agent, 8 parts by weight of hollow glass microspheres with a particle size of .

[0093] Embodiment 7:

[0094] The difference between this embodiment and embodiment 1 is that, during the preparation of the liquid crystal polymer composite material, the material introduced from the side feed port includes, in addition to the mixture of zeolite molecular sieve and coupling agent, 3 parts by weight of polytetrafluoroethylene.

[0095] Comparative Example 1:

[0096] The difference between this comparative example and Example 1 is that the monomer indole-2,6-dicarboxylic acid used in the liquid crystal polymer resin is replaced by an equal molar amount of 2,6-naphthalene dicarboxylic acid.

[0097] Comparative Example 2:

[0098] The difference between this comparative example and Example 1 is that the monomer tetra-tert-butylbiphenol used in the liquid crystal polymer resin is replaced with an equal molar amount of biphenol.

[0099] Comparative Example 3:

[0100] The difference between this comparative example and Example 1 is that the liquid crystal polymer composite material does not contain the silane coupling agent KH560, that is, the liquid crystal polymer resin and the ZSM-5 molecular sieve are directly blended in a screw extruder.

[0101] Comparative Example 4:

[0102] The difference between this comparative example and Example 1 is that the liquid crystal polymer composite material does not contain ZSM-5 molecular sieve and silane coupling agent KH560, that is, the liquid crystal polymer composite material refers to only liquid crystal polymer resin.

[0103] Comparative Example 5:

[0104] The difference between this comparative example and Example 1 is that the amount of ZSM-5 molecular sieve added to the liquid crystal polymer composite material is 10 parts by weight.

[0105] Comparative Example 6:

[0106] The difference between this comparative example and Example 1 is that the amount of ZSM-5 molecular sieve added to the liquid crystal polymer composite material is 45 parts by weight.

[0107] The liquid crystal polymer composite materials obtained in Examples 1-7 and Comparative Examples 1-6 were subjected to relevant performance tests. The specific test results are shown in Table 1.

[0108] The test method is as follows:

[0109] 1. Dielectric constant and dielectric loss factor: Take the liquid crystal polymer composite material obtained by the twin-screw extruder, use a single-screw injection molding machine to mold a 100mm*100mm*1mm square plate, and test the dielectric constant and dielectric loss factor of the sample at 10GHz according to the IEC62562-2010 method;

[0110] 2. Impact strength: Cantilever arm notch impact strength test is carried out in accordance with ISO 180 / 1U standard;

[0111] 3. Tensile strength: The tensile strength test is carried out on a tensile testing machine in accordance with ISO 527-2 standard.

[0112] Table 1

[0113]

[0114]

[0115] It can be seen from the test data in Table 1 that the liquid crystal polymer composite material obtained by the preparation method of the present invention has a lower dielectric constant, dielectric loss, and better impact strength and tensile strength, which meets the requirements of electronic component materials in the 5G and 6G communication fields for dielectric properties and mechanical properties.

[0116] By comparing the data of Example 1 with those of Comparative Examples 1-2, it can be seen that when the liquid crystal polymer resin polymerization monomer raw materials used are changed, the dielectric loss of the liquid crystal polymer composite material will be greatly increased, and the liquid crystal polymer composite material obtained by using the specific ratio of polymerization monomers of the present invention has a lower dielectric constant and dielectric loss.

[0117] By comparing the data of Example 1 with that of Comparative Example 3, it can be seen that the dielectric constant and dielectric loss of the composite material using the silane coupling agent KH560 are reduced, and the mechanical properties are also maintained better, compared with the composite material directly blending the liquid crystal polymer resin and the zeolite molecular sieve without using the silane coupling agent KH560, indicating that the specific silane coupling agent of the present invention improves the interface between the liquid crystal polymer resin and the zeolite molecular sieve.

[0118] By comparing the data of Example 1 with that of Comparative Example 4, it can be seen that by simultaneously adding zeolite molecular sieve and silane coupling agent to the composite material, the dielectric constant of the liquid crystal polymer composite material can be greatly reduced and better mechanical properties can be maintained.

[0119] By comparing the data of Comparative Examples 5-6 with Example 1 and Comparative Example 1, it can be seen that when the addition amount of zeolite molecular sieve is too high or too low, the dielectric constant will increase. The main reasons are: when the addition amount of zeolite molecular sieve is too low, it is not enough to cause a significant decrease in the dielectric constant; when the addition amount of zeolite molecular sieve is too high, although the excessive addition amount of zeolite can introduce more total air, the addition amount is too high, and the zeolite powder cannot be completely coated by the liquid crystal polymer resin, resulting in the agglomeration of zeolite particles to form large particles, which intensifies the polarization of the interface between the resin and the zeolite, thereby increasing the dielectric constant of the composite material.

[0120] By comparing Examples 6-7 with Example 1, it can be seen that when a small amount of hollow glass microspheres or polytetrafluoroethylene is added, the dielectric constant and dielectric loss of the liquid crystal polymer composite material can be further reduced without causing a significant impact on the mechanical properties.

[0121] Without violating the spirit of the present invention, insulating carbon black can also be added to the liquid crystal polymer composite material of the present invention according to the actual needs of electronic connection device customers, so as to obtain a black liquid crystal polymer composite material while maintaining the stability of various properties.

Claims

1. A method for preparing a liquid crystal polymer composite material, characterized in that The preparation method is carried out according to the following steps: Step S1: mixing p-hydroxybenzoic acid, indole-2,6-dicarboxylic acid and tetra-tert-butyldiphenol with an acylating agent, acetic anhydride and a catalyst to obtain a mixture a; The molar ratio of p-hydroxybenzoic acid, indole-2,6-dicarboxylic acid and tetra-tert-butylbiphenol is (64-80): (10-18): (10-18); Step S2: subjecting the mixture a obtained in step S1 to a prepolymerization reaction to obtain a prepolymer; Step S3: Under an inert gas atmosphere, subjecting the prepolymer obtained in step S2 to a solid phase polycondensation reaction to obtain a liquid crystal polymer resin; Step S4: adding 15 to 40 parts by weight of zeolite molecular sieve to an ethanol solution, adding 1 to 5 parts by weight of a silane coupling agent KH560 after ultrasonic dispersion, and then stirring and reacting at a temperature of 60 to 70° C. for 3 to 5 hours, and then filtering and drying to obtain a mixture b; Step S5: adding 100 parts by weight of the liquid crystal polymer resin obtained in step S3 and the mixture b obtained in step S4 into a twin-screw extruder, and extruding a strip to obtain a liquid crystal polymer strip composite material; Step S6: The liquid crystal polymer strip composite material obtained in step S5 is fed into a pelletizer through an air-cooled conveyor belt for pelletizing to obtain a liquid crystal polymer composite material.

2. The method for preparing a liquid crystal polymer composite material according to claim 1, characterized in that The amount of acetic anhydride added as the acylating agent in step S1 is 1.5 to 3.0 times the total molar number of hydroxyl groups in p-hydroxybenzoic acid, indole-2,6-dicarboxylic acid and tetra-tert-butylbiphenol.

3. The method for preparing a liquid crystal polymer composite material according to claim 1, characterized in that The amount of the catalyst added in step S1 is 0.006-0.01% of the total mass of p-hydroxybenzoic acid, indole-2,6-dicarboxylic acid and tetra-tert-butyldiphenol, and the catalyst is potassium acetate.

4. The method for preparing a liquid crystal polymer composite material according to claim 1, characterized in that The prepolymerization reaction described in step S2 is carried out according to the following steps: heating the mixture a to 130-150° C. and keeping it warm at 130-150° C. for 1-3 hours; after the insulation is completed, heating it to 300-350° C. and continuing to keep it warm at 300-350° C. for 2-4 hours; after the insulation is completed, crushing it, passing it through a 30-mesh sieve, and then drying it at 120-140° C. for 1-2 hours to obtain a prepolymer.

5. The method for preparing a liquid crystal polymer composite material according to claim 1, characterized in that The solid phase polycondensation reaction in step S3 is carried out at a temperature of 300 to 350° C. for 12 to 24 hours.

6. The method for preparing a liquid crystal polymer composite material according to claim 1, characterized in that The volume ratio of the zeolite molecular sieve to the ethanol solution in step S4 is 1:(1.5-2.5).

7. The method for preparing a liquid crystal polymer composite material according to claim 1 or 6, characterized in that The zeolite molecular sieve is one or more of ZSM-5, ZSM-11, ZSM-12 and ZSM-23 molecular sieves; the pore size of the zeolite molecular sieve is 0.42-0.59 nm, and the particle size is 0.5-0.8 μm.

8. The method for preparing a liquid crystal polymer composite material according to claim 1 or 6, characterized in that The concentration of the ethanol solution in step S4 is 95%.

9. The method for preparing a liquid crystal polymer composite material according to claim 1, characterized in that When 100 parts by weight of the liquid crystal polymer resin and the mixture b are added to the twin-screw extruder in step S5, 5 to 10 parts by weight of hollow glass microspheres and 1 to 4 parts by weight of polytetrafluoroethylene or both are added simultaneously.

10. The method for preparing a liquid crystal polymer composite material according to claim 1, characterized in that In step S5, the temperature of the twin-screw extruder is set to 290-370° C., and the screw speed is set to 200-300 r / min.

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