Liquid crystal polymer, liquid crystal composition and preparation method and application thereof

Abstract

The invention relates to a liquid crystal polymer, a liquid crystal composition and a preparation method and application thereof. The zero-shear viscosity of the liquid crystal polymer is 3500-8000 Pa.s, and the melting enthalpy is greater than or equal to 1.2 J / g. The liquid crystal composition prepared from the liquid crystal polymer disclosed by the invention is not easy to fall powder under the ultrasonic action, has good flatness, also has good weld line strength, and is very suitable for preparing optical instrument parts, especially camera module workpieces.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and more specifically, to a liquid crystal polymer, a liquid crystal composition, a preparation method thereof, and an application thereof. Background Art

[0002] Liquid crystal polymer (LCP) has excellent dimensional stability, heat resistance and fluidity, and can be used to prepare precision instrument components.

[0003] In precision instruments, especially optical instruments with lenses, etc., slight dirt, dust, etc. will affect the performance of the instruments. For example, for the components used in the optical instruments of camera modules, when minute oil, dust or oil stains adhere to the lens, the optical characteristics of the camera will decrease significantly, affecting the imaging effect and aesthetics. In order to avoid the above situation, usually the camera module components are ultrasonically cleaned before assembly to remove the minute dirt, oil, dust, etc. attached to the surface.

[0004] Due to its rigid molecular chain structure, liquid crystal polymer is extremely easy to orient along the flow direction, forming an obvious skin-core structure. The skin-core structure has obvious orientation, resulting in easy interlayer peeling on the material surface under the action of external force. This causes the material surface to easily shed powder and form microparticles during ultrasonic cleaning, which is the main reason for the generation of dirt during ultrasonic cleaning, and the fallen dust is likely to have an adverse impact on the camera's photographing pixels.

[0005] In addition, since it is a component of a precision instrument, attention should be paid to the surface flatness and weld line strength of the liquid crystal polymer material to meet the requirements of the precision and reliability of the components after injection molding.

[0006] CN107924039A provides a liquid crystalline resin composition for a camera module, and its anti-powder-shedding performance and flatness need to be further improved.

[0007] CN101981123A provides a liquid crystal polyester resin composition for a camera module, and its anti-powder-shedding performance also needs to be further improved, and the flatness of the material is not concerned. Summary of the Invention

[0008] The primary object of the present invention is to overcome the technical problems existing in the above-mentioned prior art and provide a liquid crystal polymer.

[0009] A further object of the present invention is to provide a liquid crystal composition.

[0010] A further object of the present invention is to provide a preparation method of the above liquid crystal composition.

[0011] A further object of the present invention is to provide an application of the above liquid crystal composition in the preparation of optical instrument components.

[0012] The above object of the present invention is achieved by the following technical solutions:

[0013] A liquid crystal polymer, wherein the zero shear viscosity of the liquid crystal polymer is 3500 - 8000 Pa·s, and the melting enthalpy ≥ 1.2 J / g.

[0014] The inventors of the present invention have found through research that the liquid crystal composition prepared from the liquid crystal polymer of the present invention is not prone to powder dropping under the action of ultrasonic waves, has good flatness, and also has good weld line strength, and is very suitable for preparing optical instrument components, especially camera module components.

[0015] A liquid crystal composition, comprising the following components in parts by weight:

[0016] 60 - 75 parts of the above liquid crystal polymer,

[0017] 20 - 40 parts of filler.

[0018] The addition of the filler of the present invention can improve the basic mechanical properties of the liquid crystal composition.

[0019] The inventors of the present invention have found through research that by controlling the zero shear viscosity of the liquid crystal polymer within a certain range, not only can the problem of easy powder dropping of the liquid crystal composition under ultrasonic waves be improved, but also the flatness of the liquid crystal composition can be improved to a certain extent. The principle is as follows: when the zero shear viscosity of the liquid crystal polymer is within a certain range, the molecular chains of the liquid crystal polymer can reach an appropriate length, which is beneficial to the entanglement between the molecules of the liquid crystal polymer, slows down the delamination of the liquid crystal polymer under the action of ultrasonic waves, and improves the anti-powder dropping performance; and the anisotropy of the molecular chains of the liquid crystal polymer at this zero shear viscosity is reduced, so its flatness is also improved to a certain extent.

[0020] However, the zero shear viscosity of the liquid crystal polymer should not be further increased, otherwise the compatibility between the liquid crystal polymer and the filler will become poor, and the anti-powder dropping performance and flatness will deteriorate. The inventors further found that by controlling the melting enthalpy of the liquid crystal polymer within a certain range, the problem of easy powder dropping of the liquid crystal composition under ultrasonic waves can be further improved, and the flatness of the liquid crystal composition can be effectively improved. This is because when the melting enthalpy is controlled within a certain range, the degree of ordered and regular arrangement of the molecular chains of the liquid crystal polymer is increased, the free volume is reduced, the intermolecular interaction force is enhanced, the anti-powder dropping performance of the material is improved, and at the same time, the increase in the melting enthalpy can increase the material modulus, and thus improve the flatness of the liquid crystal polymer.

[0021] In addition, through the cooperation of the specific zero shear viscosity and melting enthalpy of the liquid crystal polymer, the weld line strength of the liquid crystal composition is improved, including the weld line tensile strength and the weld line bending strength.

[0022] In the present invention, a liquid crystal polymer serves as the host resin; preferably, the liquid crystal polymer accounts for more than 50 wt% of the liquid crystal composition.

[0023] In the present invention, the zero-shear viscosity of the liquid crystal polymer can specifically be 3500, 3600, 3700, 3900, 4100, 4300, 4500, 4800, 5000, 5500, 6000, 6500, 7000, 7300, 7500, 7600, 7800 or 8000 Pa·s.

[0024] Preferably, the zero-shear viscosity of the liquid crystal polymer is 5000 - 6450 Pa·s. In this range, the properties of the obtained liquid crystal composition are better.

[0025] Commonly used liquid crystal polymers in the art can all be used in the present invention.

[0026] Preferably, the liquid crystal polymer is a liquid crystal polyester.

[0027] More preferably, the liquid crystal polymer includes the following repeating units:

[0028] -O-Ar1-CO- 50 - 60 mol%,

[0029] -CO-Ar2-CO- 20 - 25 mol%,

[0030] -O-Ar3-O- 20 - 25 mol%;

[0031] Among them, Ar1 is at least one of phenylene or naphthylene, and Ar2 and Ar3 are independently at least one of phenylene, biphenylene or naphthylene.

[0032] Further preferably, the preparation process of the liquid crystal polymer is as follows: The monomers corresponding to the -O-Ar1-CO- repeating unit, the monomers corresponding to the -CO-Ar2-CO- repeating unit, and the monomers corresponding to the -O-Ar3-O- repeating unit are successively subjected to acylation reaction, polycondensation reaction and solid-phase viscosity increase to obtain the product.

[0033] Further preferably, the monomer corresponding to the -O-Ar1-CO- repeating unit is at least one of p-hydroxybenzoic acid, m-hydroxybenzoic acid, o-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, 3-hydroxy-2-naphthoic acid or 1-hydroxy-2-naphthoic acid.

[0034] Further preferably, the monomer corresponding to the -CO-Ar2-CO- repeating unit is at least one of terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid or 4,4'-biphenyldicarboxylic acid.

[0035] Further preferably, the monomer corresponding to the -O-Ar3-O- repeating unit is at least one of p,p'-biphenol, hydroquinone, or 2,6-naphthalenediol.

[0036] Further preferably, the acylation reaction is carried out in the presence of an acylating agent.

[0037] Further preferably, the acylating agent is acetic anhydride.

[0038] Further preferably, the temperature of the acylation reaction is 140 - 190 °C, and the time is 0.5 - 4 hours.

[0039] Further preferably, the temperature is raised from room temperature (20 - 30 °C) to the temperature of the acylation reaction at a rate of 1.5 - 3 °C / min.

[0040] Further preferably, the temperature of the polycondensation reaction is higher than the temperature of the acylation reaction, and the temperature is raised from the temperature of the acylation reaction to the temperature of the polycondensation reaction at a rate of 2.0 - 5.5 °C / min.

[0041] Further preferably, the temperature of the polycondensation reaction is 300 - 400 °C, and the pressure is below 10 kPa.

[0042] Further preferably, the pressure is 1 - 10 kPa.

[0043] Further preferably, the polycondensation reaction is carried out in a reaction kettle, and the polycondensation reaction is terminated when the power of the stirring paddle of the reaction kettle rises to 1 - 10 kW.

[0044] Further preferably, the temperature of the solid-phase viscosity increase is 280 - 320 °C, and the time is 11 - 16 hours.

[0045] As the manufacturing method of the liquid crystal resin used in the present invention, a known method can be adopted, a manufacturing method only through melt polymerization can be adopted, or a two-stage polymerization manufacturing method of melt polymerization and solid-phase polymerization can be adopted.

[0046] The zero-shear viscosity of the liquid crystal polymer of the present invention can be adjusted by any method known in the art. For example, the liquid crystal polymer purchased or obtained by melt polymerization can be subjected to solid-phase viscosity increase, and the zero-shear viscosity can be regulated by adjusting the time and / or temperature of the solid-phase viscosity increase, etc.; the melting enthalpy of the liquid crystal polymer of the present invention can be adjusted by any method known in the art. For example, it can be adjusted by parameters such as the type of monomer, the dosage ratio of monomers, the temperature and time of melt polymerization, the temperature and time of solid-phase viscosity increase, and the heating rate at different stages (such as: the heating rate from room temperature to the reaction temperature of the acylation reaction, the heating rate from the reaction temperature of the acylation reaction to the reaction temperature of the polycondensation reaction).

[0047] Regardless of the method adopted, as long as the finally prepared liquid crystal polymer meets the zero shear viscosity and melting enthalpy ranges defined in the present invention, the technical problems of the present invention can be solved.

[0048] Preferably, the zero shear viscosity of the liquid crystal polymer is 5000 - 6500 Pa·s. In this range, the problem of easy powder dropping of the liquid crystal composition under the action of ultrasonic waves is further improved, the flatness is better, and the weld line strength is also higher.

[0049] In the present invention, the melting enthalpy of the liquid crystal polymer can specifically be 1.20, 1.25, 1.30, 1.40, 1.50, 1.60, 1.70 or 1.80 J / g.

[0050] Preferably, the melting enthalpy of the liquid crystal polymer is 1.2 - 1.7 J / g.

[0051] More preferably, the melting enthalpy of the liquid crystal polymer is 1.32 - 1.60 J / g. In this range, the problem of easy powder dropping of the crystal composition under the action of ultrasonic waves is further improved, and the flatness is better.

[0052] Preferably, the melting point of the liquid crystal polymer is 320 - 360 °C.

[0053] The melting point of the liquid crystal polymer can be measured by a differential scanning calorimeter.

[0054] Preferably, the average particle size of the filler is 0.1 - 30 microns.

[0055] Preferably, the filler is a fibrous filler or a flaky filler.

[0056] More preferably, the filler includes fibrous filler and flaky filler with a mass ratio of 1:(0.8 - 1.2). Through the compounding of different fillers, the flatness of the obtained liquid crystal composition is improved.

[0057] More preferably, the fibrous filler is at least one of potassium titanate whiskers, silicon carbide whiskers or wollastonite.

[0058] Further preferably, the fibrous filler is potassium titanate whiskers. By selecting potassium titanate whiskers, the anti-powder-dropping performance of the obtained liquid crystal composition is better.

[0059] More preferably, the flaky filler is at least one of mica, talcum powder or boron nitride.

[0060] Preferably, the filler is a filler modified with a silane coupling agent.

[0061] More preferably, the silane coupling agent is at least one of an alkane-based silane coupling agent or an epoxy-based silane coupling agent.

[0062] Further preferably, the silane coupling agent is an alkane-based silane coupling agent.

[0063] When an alkane-based silane coupling agent is selected to modify the filler, the problem of powder shedding of the obtained liquid crystal composition under ultrasonic action can be further improved, and the weld line strength is also better.

[0064] Further preferably, the alkane-based silane coupling agent is at least one of n-propyltrimethoxysilane, n-octyltriethoxysilane or n-octyltrimethoxysilane.

[0065] Further preferably, the epoxy-based silane coupling agent includes, but is not limited to, epoxytrimethoxysilane.

[0066] Preferably, the liquid crystal composition further includes 0.2 to 5 parts of other additives.

[0067] More preferably, the other additives are at least one of color powder, lubricant or toughening agent.

[0068] Further preferably, the color powder is carbon black.

[0069] Further preferably, the toughening agent is an olefin copolymer, including, but is not limited to, at least one of ethylene-butyl acrylate-glycidyl methacrylate copolymer, ethylene-glycidyl methacrylate copolymer or ethylene-methyl acrylate-glycidyl methacrylate copolymer.

[0070] The preparation method of the above liquid crystal composition includes the following steps:

[0071] Mix the components and melt-extrude them to obtain the liquid crystal composition.

[0072] The application of the above liquid crystal composition in the preparation of optical instrument components is also within the protection scope of the present invention.

[0073] Preferably, the optical instrument component is a camera module component.

[0074] An optical instrument component made of the above liquid crystal composition.

[0075] Preferably, the optical instrument component is a camera module component.

[0076] Compared with the prior art, the beneficial effects of the present invention are:

[0077] (1) The liquid crystal composition prepared from the liquid crystal polymer of the present invention is not prone to powder shedding under ultrasonic action, has good flatness, and also has good weld line strength, and is very suitable for the preparation of optical instrument components, especially camera module components.

[0078] (2) The liquid crystal composition of the present invention is not prone to powder shedding under the action of ultrasound, has good flatness, and also has good weld line strength, and is very suitable for preparing optical instrument components, especially camera module parts. Detailed implementation manners

[0079] In order to describe the technical solution of the present invention more clearly and completely, the following further details the present invention through specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, and various changes can be made within the scope defined by the rights of the present invention.

[0080] Some of the reagents selected in the embodiments and comparative examples of the present invention are described as follows:

[0081] Liquid crystal polymer 1#: Self-made. The preparation process is as follows: Mix the polymerization monomers p-hydroxybenzoic acid (HBA), terephthalic acid (PTA), and biphenol (BP) in a molar ratio of 60:20:20, and put them into a reaction vessel for acetylation with acetic anhydride. Heat from room temperature (25°C) to 170°C at a heating rate of 2.5°C / min, reflux at 170°C for 2 h, and then start to extract the reaction by-product acetic acid. After the acetylation reaction is completed, heat the reaction kettle to 350°C at a heating rate of 4°C / min, discharge acetic acid and unreacted raw material small molecules from the rectification column, then reduce the internal pressure of the reaction kettle to below 5 kPa, maintain this pressure until the power of the stirring paddle reaches 3.5 kw, discharge the material and pelletize. Then transfer the material to a rotary drum, the temperature of the rotary drum is 300°C, and keep it at a constant temperature for 14 hours to obtain liquid crystal polymer 1#. The zero-shear viscosity of liquid crystal polymer 1# is 5005 Pa·s, and the melting enthalpy is 1.35 J / g.

[0082] Liquid crystal polymer 2#: Self-made. The difference in the preparation process from liquid crystal polymer 1# is that the constant temperature time of the rotary drum is extended to 16 hours. The zero-shear viscosity of liquid crystal polymer 2# is 6400 Pa·s, and the melting enthalpy is 1.34 J / g.

[0083] Liquid crystal polymer 3#: Self-made. The difference in the preparation process from liquid crystal polymer 1# is that the constant temperature time of the rotary drum is shortened to 11 hours. The zero-shear viscosity of liquid crystal polymer 3# is 4430 Pa·s, and the melting enthalpy is 1.28 J / g.

[0084] Liquid crystal polymer 4#: Self-made. The difference in the preparation process from liquid crystal polymer 1# is that after the acetylation reaction is completed, the reaction kettle is heated to 350°C at a heating rate of 2.5°C / min. The zero-shear viscosity of liquid crystal polymer 4# is 5015 Pa·s, and the melting enthalpy is 1.58 J / g.

[0085] Liquid crystal polymer 5#: Self-made. The difference in the preparation process from liquid crystal polymer 1# is that after the acylation reaction, the reaction kettle is heated to 350 °C at a heating rate of 5 °C / min. The zero-shear viscosity of liquid crystal polymer 4# is 4959 Pa·s, and the melting enthalpy is 1.26 J / g.

[0086] Liquid crystal polymer 6#: Self-made. The difference in the preparation process from liquid crystal polymer 1# is that the monomer composition used is different, and the polymerization monomers 6-hydroxy-2-naphthoic acid (HNA), terephthalic acid (PTA), and biphenol (BP) are mixed in a molar ratio of 60:20:20. The zero-shear viscosity of liquid crystal polymer 6# is 6585 Pa·s, and the melting enthalpy is 1.39 J / g.

[0087] Liquid crystal polymer 7#: Self-made. The difference in the preparation process from liquid crystal polymer 1# is that the dosage of the polymerization monomers is different, and the molar ratio of the polymerization monomers p-hydroxybenzoic acid (HBA), terephthalic acid (PTA), and biphenol (BP) is 50:25:25. The zero-shear viscosity of liquid crystal polymer 7# is 4546 Pa·s, and the melting enthalpy is 1.42 J / g.

[0088] Liquid crystal polymer 8#: Self-made. The difference in the preparation process from liquid crystal polymer 1# is that before the acylation reaction, the temperature is raised from room temperature (25 °C) to 170 °C at a heating rate of 1.5 °C / min. The zero-shear viscosity of the obtained liquid crystal polymer 8# is 5078 Pa·s, and the melting enthalpy is 1.45 J / g.

[0089] Liquid crystal polymer 9#: Self-made. The difference in the preparation process from liquid crystal polymer 1# is that the drum constant temperature time is shortened to 8 hours. The zero-shear viscosity of liquid crystal polymer 9# is 2355 Pa·s, and the melting enthalpy is 1.32 J / g.

[0090] Liquid crystal polymer 10#: Self-made. The difference in the preparation process from liquid crystal polymer 1# is that the drum temperature is increased to 310 °C and the drum constant temperature time is extended to 18 hours. The zero-shear viscosity of liquid crystal polymer 10# is 9455 Pa·s, and the melting enthalpy is 1.38 J / g.

[0091] Liquid crystal polymer 11#: Self-made. The difference in the preparation process from liquid crystal polymer 1# is that after the acylation reaction, the reaction kettle is heated to 350 °C at a heating rate of 7.5 °C / min. The zero-shear viscosity of liquid crystal polymer 11# is 5105 Pa·s, and the melting enthalpy is 0.92 J / g.

[0092] Liquid crystal polymer 12#: Prepared according to paragraphs

[0106] to

[0113] of patent CN107924039 A. The zero-shear viscosity of liquid crystal polymer 12# is 2893 Pa·s, and the melting enthalpy is 1.12 J / g.

[0093] Liquid crystal polymer 13#: Prepared according to paragraphs

[0112] to

[0114] of Patent CN101981123A. The zero-shear viscosity of liquid crystal polymer 13# is 3584 Pa·s, and the melting enthalpy is 1.09 J / g.

[0094] Liquid crystal polymer 14#: Ueno A-2500, manufactured by Ueno Pharmaceutical Co., Ltd., Japan. The zero-shear viscosity of liquid crystal polymer 14# is 3059 Pa·s, and the melting enthalpy is 1.23 J / g.

[0095] The zero-shear viscosity of the above liquid crystal polymers was measured by the following method: The liquid crystal polymer was prepared into a resin disc with a diameter of 25 mm and a thickness of 2 mm as the sample to be measured. A steady-state shear rate scan was performed on the sample to be measured using a rotational rheometer. First, the sample was heated to a temperature of Tm + 30 °C (Tm is the melting point), and held at a constant temperature for 6 min to eliminate the processing history of the sample. Then, the temperature was lowered to the set temperature Tm + 20 °C, the melt strain was fixed at 0.5%, and a scan was performed on the sample in the scanning frequency range of 0.001 - 100 s -1 to obtain the viscosity vs. shear rate curve. Then, the shear viscosity at a fixed shear rate of 0.005 s -1 was taken as the zero-shear viscosity η0.

[0096] The melting enthalpy of the above liquid crystal polymers was measured by the following method: The melting point was measured using a DSC 200F3 manufactured by NETZSCH. The heating rate was 20 °C / min. The sample was heated to Tm + 30 °C and held for 5 minutes to eliminate the thermal history. Then, it was cooled to room temperature at a rate of 20 °C / min and then heated to Tm + 40 °C at a rate of 20 °C / min. The temperature corresponding to the melting peak of the second heating curve was taken as the melting point of the material, and the melting peak was integrated to obtain the change in melting enthalpy.

[0097] Silane coupling agent 1#: An alkane-based silane coupling agent, n-propyltrimethoxysilane, Nanjing Pining Coupling Agent Co., Ltd., China;

[0098] Silane coupling agent 2#: An epoxy-based silane coupling agent, epoxytrimethoxysilane, Z-6040, Dow Corning, USA;

[0099] Filler 1#: Mica, GM-501, with an average particle size of 15 μm, Chuzhou Gerui Mining Co., Ltd., China;

[0100] Filler 2#: Potassium titanate whiskers, with an average particle size of 3 μm, Nantong Aoxin Electronic Technology Co., Ltd., China;

[0101] Filler 3#: Talc powder, with an average particle size of 12 μm, Guangxi Longsheng Huamei Talc Development Co., Ltd., China;

[0102] Filler 4#: Wollastonite, HK-5000F, average particle size 2.5 microns, Dalian Global Minerals Co., Ltd.;

[0103] Filler 5#: Boron nitride (BN), average particle size 13 μm, Qinhuangdao Yinuo Advanced Materials Co., Ltd.;

[0104] Modified filler 1#: Obtained by mixing Filler 1# and silane coupling agent 1# in a mass ratio of 1:0.02 in a high-speed mixer;

[0105] Modified filler 2#: Obtained by mixing Filler 2# and silane coupling agent 1# in a mass ratio of 1:0.02 in a high-speed mixer;

[0106] Modified filler 3#: Obtained by mixing Filler 3# and silane coupling agent 1# in a mass ratio of 1:0.02 in a high-speed mixer;

[0107] Modified filler 4#: Obtained by mixing Filler 1# and silane coupling agent 2# in a mass ratio of 1:0.02 in a high-speed mixer;

[0108] Modified filler 5#: Obtained by mixing Filler 4# and silane coupling agent 1# in a mass ratio of 1:0.02 in a high-speed mixer;

[0109] Modified filler 6#: Obtained by mixing Filler 5# and silane coupling agent 1# in a mass ratio of 1:0.02 in a high-speed mixer;

[0110] Other additive 1#: Toughening agent, PTW, ethylene-methyl acrylate glycidyl methacrylate copolymer, DuPont, USA;

[0111] Other additive 2#: Colorant, carbon black, commercially available.

[0112] Unless otherwise specified, each component (such as Other additive 1# etc.) selected in each parallel example and comparative example is the same commercially available product.

[0113] The liquid crystal compositions provided in each example and comparative example of the present invention are subjected to performance determination according to the following test methods:

[0114] 1) Powder dropping evaluation method: Cut the above test piece into a 10 mm × 10 mm × 1 mm sample piece, place it in water (20 ml) at room temperature in an ultrasonic cleaner (power 300 W, frequency 45 kHz) for 5 minutes. Then, use a particle counter (Particle Counter KE-40B1 of RION Co., Ltd., Japan). Measure the number of particles with a particle size of 10 μm or more present in the above water, and evaluate it as the number of microdust generated.

[0115] 2) Flatness evaluation: Take the liquid crystal composition and use an injection molding machine to mold it under the following molding conditions to obtain a 64mm×64mm×1.0mm molded body. Use this molded body as a test piece, and after high-temperature reflow soldering, test the deformation in the vertical direction of flow under the secondary element. Injection molding barrel temperature: 360℃; mold temperature: 100℃, injection speed: 50mm / s.

[0116] 3) Weld line mechanical properties test: Use a mold with a dumbbell-shaped cavity (two-point injection, fluid impact to form a weld line) to inject a mechanical spline with a thickness of 0.8mm. Tensile strength test: Use 2019-ISO527-1 / -2 conditions, 10mm / min tensile speed for testing, and take the average of 5 test results. Flexural modulus test: Use ISO178 conditions, 2mm / min bending speed for testing, and take the average of 5 test results.

[0117] The preparation process of the liquid crystal composition of each embodiment and comparative example of the present invention is as follows: each component is weighed according to the formula, each component is added to a twin-screw extruder, melt-extruded at a temperature 20°C higher than the melting point of the liquid crystal polymer, cooled, and granulated to obtain a liquid crystal composition. The screw speed of the twin-screw extruder is 400 rpm, and the screw aspect ratio is 40:1.

[0118] Examples 1 to 17

[0119] Examples 1 to 17 provide a series of liquid crystal compositions, whose formulas are shown in Table 1.

[0120] Table 1 Formulas of Examples 1 to 17 (parts by weight)

[0121]

[0122]

[0123] Table 1

[0124]

[0125] Comparative Examples 1 to 6

[0126] Comparative Examples 1 to 6 provide a series of liquid crystal compositions, whose formulas are shown in Table 2.

[0127] Table 2 Formulas of Comparative Examples 1 to 6 (parts by weight)

[0128]

[0129]

[0130] The properties of the liquid crystal compositions of each example and comparative example were measured according to the above-mentioned test methods, and the test results are shown in Table 3.

[0131] Table 3 Test Results of the Properties of the Liquid Crystal Compositions of Each Example and Comparative Example

[0132]

[0133]

[0134] As can be seen from Table 3:

[0135] The number of micropowders in Examples 1 to 17 does not exceed 7, and the flatness is not higher than 0.28, indicating that the liquid crystal composition of the present invention is not prone to powder loss and has good flatness under the action of ultrasound. In addition, the tensile strength of the weld line in Examples 1 to 17 is not lower than 40 MPa, and the flexural strength of the weld line is not lower than 49 MPa, indicating that the weld line strength of the liquid crystal composition of the present invention is good. The above makes the liquid crystal composition of the present invention can be used to prepare camera module parts.

[0136] In Comparative Example 1, the zero shear viscosity of the liquid crystal polymer added is too small, and the liquid crystal composition is prone to powder loss and has poor weld line strength under the action of ultrasound, and the flatness is worse than that of Example 1. In Comparative Example 2, the zero shear viscosity of the liquid crystal polymer added is too large, and the liquid crystal composition is prone to powder loss under the action of ultrasound, and the flatness is worse than that of Example 1. In Comparative Example 3, the melting enthalpy of the liquid crystal composition added is too small, and the liquid crystal composition is prone to powder loss and has poor flatness and poor weld line strength under the action of ultrasound. The zero shear viscosity and / or melting enthalpy of the liquid crystal compositions used in Comparative Examples 4, 5 and 6 are not suitable, and the anti-powder loss performance, flatness and weld line strength of the liquid crystal compositions are inferior to those of Examples 1 and 4 to 10.

[0137] Obviously, the above-mentioned embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limiting the embodiments of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made on the basis of the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent replacements and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A liquid crystal polymer, characterized in that: The zero shear viscosity of the liquid crystal polymer is 3500-8000 Pa.s, and the melting enthalpy is ≥1.2 J / g.

2. A liquid crystal composition, characterized in that: The composition comprises the following components in parts by weight: Liquid crystal polymer 60-75 parts, 20-40 parts of filler; The zero shear viscosity of the liquid crystal polymer is 3500-8000 Pa.s, and the melting enthalpy is ≥1.2 J / g.

3. The liquid crystal composition according to claim 2, characterized in that: The liquid crystal polymer is a liquid crystal polyester.

4. The liquid crystal composition according to claim 2, characterized in that: The melting enthalpy of the liquid crystal polymer is 1.2 to 1.8 J / g.

5. The liquid crystal composition according to claim 2, characterized in that: The filler is a filler modified by a silane coupling agent.

6. The liquid crystal composition according to claim 2, characterized in that: The filler is at least one of a fibrous filler or a flaky filler; preferably, the fibrous filler is at least one of potassium titanate whiskers, silicon carbide whiskers or wollastonite, and the flaky filler is at least one of mica, talc or boron nitride.

7. The liquid crystal composition according to claim 2, characterized in that: The liquid crystal composition further comprises 0.2 to 5 parts of other auxiliary agents.

8. The method for preparing the liquid crystal composition according to any one of claims 2 to 7, characterized in that: The steps include: The components are mixed and melt-extruded to obtain the liquid crystal composition.

9. Use of the liquid crystal composition according to any one of claims 2 to 7 in the preparation of optical instrument components; preferably, the optical instrument component is a camera module.

10. An optical instrument component, characterized in that: Made from the liquid crystal composition described in any one of claims 2 to 7; preferably, the optical instrument component is a camera module component.

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