Liquid crystal polymer particle, liquid crystal polymer film and preparation method thereof

Abstract

The invention relates to a liquid crystal polymer particle, a liquid crystal polymer film and a preparation method thereof, the preparation method of the liquid crystal polymer particle comprises the following steps: heating and blending a tackifier and a compatibilizer in advance to obtain a liquid crystal polymer resin modifier, the tackifier at least comprising an oxygen-containing functional group; the compatibilizer at least contains a plurality of active groups and is used for forming a coupling reaction with the oxygen-containing functional group and the liquid crystal polymer resin; the liquid crystal polymer resin modifier and liquid crystal polymer resin are subjected to blending treatment and then are subjected to melt extrusion through a screw extruder to form liquid crystal polymer particles. Compared with the prior art, the melt strength is improved, and meanwhile it can be guaranteed that a film body prepared through a film blowing method has the good continuous film forming property and the like.

Description

Technical Field

[0001] The present application relates to the field of polymer films, and in particular to a liquid crystal polymer particle, a liquid crystal polymer film and a preparation method thereof. Background Art

[0002] Liquid crystal polymer (LCP) materials are widely used in the electronics field due to their unique properties, such as high temperature resistance, high-strength mechanical properties, superior electrical properties and processing performance. They are also one of the preferred materials in the 5G communication field.

[0003] At present, the main methods for preparing LCP films include blown film method, cast film method and coating method. Among them, the coating method requires the use of an appropriate solvent to dissolve LCP to achieve coating film formation. However, this process will produce a large amount of waste solvent, which brings challenges of environmental pollution and solvent recovery. In addition, the mechanical properties of the film prepared by the cast film method in the longitudinal and transverse directions will be different, thus affecting the overall performance of the film. The blown film method can make the prepared LCP film have more balanced mechanical properties in the longitudinal and transverse directions by controlling the blowing ratio and rotating the die head. In addition, compared with the cast film method, the blown film method can obtain a film with more uniform thickness through an annular die extrusion blowing, reducing the fluctuation of the film thickness. However, due to the rigidity of the LCP molecular chain, it is easy to have molecular chain orientation during the blown film forming process, the degree of disentanglement between molecular chains is high, and the melt strength is prone to a sharp drop. When the drafting rate is increased, the formation of film bubbles and the stability of film bubbles will be greatly affected.

[0004] In order to improve this problem, many methods for enhancing melt strength have been studied at home and abroad, including solid phase polycondensation, tackifier blending and other methods. Solid phase polycondensation is the process of heating LCP resin to above the glass transition temperature and below the melting point for polycondensation reaction. By blending with tackifiers, the condensation reaction of the terminal hydroxyl group and the terminal carboxyl group of LCP can increase the molecular weight of LCP, thereby improving the melt strength of LCP. Blending LCP with tackifiers is to increase the melt strength and improve the film-forming properties of the resin by destroying the rigidity of the LCP molecular chain segments and reducing the degree of disentanglement of LCP during processing. However, the above methods still have defects such as: for example, although solid phase polycondensation of LCP is beneficial to improve its melt strength at low extrusion volume, the LCP after solid phase polycondensation is still a linear structure. When the extrusion volume is increased, the increase in the screw shear rate will still cause disentanglement between molecular chains, resulting in a sharp drop in the melt strength of LCP. However, the common tackifiers are prone to poor compatibility with LCP by thickening and blending, and are unevenly dispersed in the LCP matrix, resulting in uneven melt strength, unstable film bubbles, and difficulty in achieving continuous film formation of LCP. In addition, due to the poor compatibility of the tackifier with LCP, the amount of the tackifier added to LCP cannot be too high, so the improvement of the melt strength of LCP is very limited. In addition, the prior art generally uses epoxy chain extenders to modify liquid crystal polymer resins (LCP), but as Figure 1 As shown, the epoxy chain extender binds to the branched chain X in the liquid crystal polymer resin (LCP) and forms a polymer molecular brush of a brush-type structure, which greatly affects the liquid crystal properties of the liquid crystal polymer resin (LCP).

[0005] Therefore, how to provide a liquid crystal polymer particle, a liquid crystal polymer film and a preparation method thereof, so as to improve its melt strength while ensuring that the film prepared by the film blowing method has good continuity, is a technical problem that urgently needs to be solved in this application. Summary of the invention

[0006] The purpose of the present application is to provide a liquid crystal polymer particle, a liquid crystal polymer film and a preparation method thereof, which can improve the melt strength thereof while ensuring that the film prepared by the film blowing method has good continuity.

[0007] In order to achieve the above object, the present application proposes a method for preparing liquid crystal polymer particles, comprising the following steps:

[0008] The liquid crystal polymer resin modifier is obtained by pre-heating and blending the tackifier and the compatibilizer, wherein the tackifier includes at least an oxygen-containing functional group; and the compatibilizer contains at least a plurality of active groups for forming a coupling reaction with the oxygen-containing functional group.

[0009] The liquid crystal polymer resin modifier is blended with the liquid crystal polymer resin and then melt-extruded through a screw extruder to form liquid crystal polymer particles.

[0010] Further preferably, the step of obtaining the liquid crystal polymer resin modifier after pre-heating and blending the tackifier and the compatibilizer comprises:

[0011] The tackifier and the compatibilizer are blended in a high-speed mixer at a temperature of 80 to 150° C. and a rotation speed of 3000 to 5000 rpm to obtain the liquid crystal polymer resin modifier.

[0012] Further preferably, the step of blending the liquid crystal polymer resin modifier with the liquid crystal polymer resin and then extruding the mixture through a screw extruder to form liquid crystal polymer particles comprises:

[0013] The liquid crystal polymer resin modifier and the liquid crystal polymer resin are blended and stirred, and then melt-extruded through a screw extruder, wherein the temperature of the screw extrusion zone is 200-350° C., the screw speed of the screw extruder is 100-150 rpm; and the terminal temperature of the screw extrusion zone is greater than or equal to 295° C.

[0014] Further preferably, the mass ratio of the liquid crystal polymer resin modifier to the liquid crystal polymer particle liquid crystal polymer resin before blending is 5:95;

[0015] And / or, the mass ratio of the tackifier to the compatibilizer is (0.5-0.8):4.5.

[0016] Further preferably, the mass percentage of the tackifier in the liquid crystal polymer particles is 1%-20%.

[0017] Further preferably, the mass percentage of the tackifier in the liquid crystal polymer particles is 3%-6%.

[0018] Further preferably, the mass percentage of the compatibilizer in the liquid crystal polymer particles is 0.1%-3%.

[0019] Further preferably, the mass percentage of the compatibilizer in the liquid crystal polymer particles is 0.45%-1%.

[0020] Further preferably, the oxygen-containing functional group at least includes: a carboxyl group;

[0021] and / or, hydroxyl group;

[0022] Further preferably, the active groups at least include: oxazoline group;

[0023] And / or, the active group is a bifunctional group.

[0024] Further preferably, the tackifier includes any one or a combination of two or more of polyarylate, polyetheretherketone, polyimide, polysulfone, polyphenylene ether, polycarbonate, polyethylene naphthalate and polyethylene terephthalate.

[0025] Further preferably, the compatibilizer includes any one of diisocyanate, maleic anhydride, bis-oxazoline compounds, and diepoxy compounds, or a combination thereof.

[0026] Further preferably, the compatibilizer is 2,2'-bis(2-oxazoline) or 2,2'-(1,4-phenylene)bis(2-oxazoline);

[0027] And / or, the liquid crystal polymer resin is one of A950 and R8000 or a mixture of two or more thereof.

[0028] The present application also provides a liquid crystal polymer particle, which is prepared by the above-mentioned preparation method of the liquid crystal polymer particle.

[0029] Further preferably, the present application provides a method for preparing a liquid crystal polymer film, wherein the liquid crystal polymer particles are processed by a film blowing method.

[0030] Further preferably, the present application provides a liquid crystal polymer film, which is prepared by the above-mentioned method for preparing a liquid crystal polymer film.

[0031] Compared with the prior art, the beneficial effects of the present application are mainly reflected in: while improving its melt strength, it can also ensure that the film prepared by the film blowing method has good continuity, etc., especially by adopting a pre-blending method, the compatibilizer and the thickener are pre-blended at a suitable reaction temperature in the active groups such as oxazoline and the oxygen-containing groups such as carboxyl or hydroxyl, which effectively improves the dispersion and mixing effect between the compatibilizer and the thickener, and also prevents the uneven dispersion of the compatibilizer in the thickener and the LCP matrix, resulting in serious gelation.

[0032] In addition, the compatibilizer in the present application may preferably contain a bifunctional active group for forming a coupling reaction with an oxygen-containing functional group and a liquid crystal polymer resin, wherein the compatibilizer and the thickener first react to form a modifier, and then combine with the liquid crystal polymer resin (LCP) through a coupling reaction, thereby improving the compatibility of the LCP and the thickener through the reaction of the small molecule functional group with the thickener and the LCP end group, reducing the degree of damage to the liquid crystallinity of the LCP, and thereby making the prepared LCP film better suitable for 5G communication materials, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of the reaction principle of epoxy chain extender and LCP resin in the prior art;

[0034] Figure 2 Schematic diagram of the reaction mechanism of PEN and LCP using bisoxazoline as a compatibilizer in this application;

[0035] Figure 3 is a schematic diagram of a process for preparing liquid crystal polymer particles in this application;

[0036] Figure 4 Schematic diagram of the change of viscosity of liquid crystal polymer particles with shear frequency in each embodiment of the present application;

[0037] Figure 5 This is a photo of film blowing during the process of preparing a liquid crystal polymer film from liquid crystal polymer particles in Comparative Example 1 of the present application;

[0038] Figure 6 This is a schematic diagram of film blowing in the process of preparing a liquid crystal polymer film from liquid crystal polymer particles in Example 1 of the present application;

[0039] Figure 7 This is a schematic diagram of film blowing in the process of preparing a liquid crystal polymer film from liquid crystal polymer particles in Example 2 of the present application;

[0040] Figure 8 This is a schematic diagram of film blowing in the process of preparing a liquid crystal polymer film from liquid crystal polymer particles in Example 3 of the present application. DETAILED DESCRIPTION

[0041] The following is a more detailed description of the preparation method of the liquid crystal polymer film of the present application in conjunction with the schematic diagram, wherein the preferred embodiment of the present application is shown, and it should be understood that those skilled in the art can modify the present application described herein, while still achieving the beneficial effects of the present application. Therefore, the following description should be understood as being widely known to those skilled in the art, and not as a limitation to the present application.

[0042] In some embodiments of the present invention, the method for preparing liquid crystal polymer particles comprises the following steps:

[0043] Step S1: preheating and blending the tackifier and the compatibilizer to obtain a liquid crystal polymer resin modifier;

[0044] Step S2: blending the liquid crystal polymer resin modifier with the liquid crystal polymer resin, and extruding to form liquid crystal polymer particles.

[0045] The specific steps are as follows:

[0046] In the above step S1, specifically as follows: pre-blending and heating the tackifier and the compatibilizer, calculating by weight, weighing 1 to 20 parts of the tackifier and 0.1 to 3 parts of the compatibilizer, and then blending and heating the mixture in a high-speed mixer at a temperature of 80 to 150° C. and a rotation speed of 3000 to 5000 rpm to obtain a liquid crystal polymer resin modifier. The specific tackifier used is selected from any one or a combination of two or more of polyarylate, polyetheretherketone, polyimide, polysulfone, polyphenylene oxide, polycarbonate, polyethylene naphthalate and polyethylene terephthalate. The specific compatibilizer used is selected from any one or a combination of bisoxazoline compounds, polyisocyanates, pyromellitic anhydride, diepoxy compounds, triphenyl phosphite, carboxylic acid chain extenders, organic peroxides and epoxy chain extenders.

[0047] In the above step S2, specifically as follows: the liquid crystal polymer resin modifier and the liquid crystal polymer resin are uniformly stirred at a low speed in a stirrer under low temperature conditions to achieve blending, and then input into a screw extruder and extruded to form liquid crystal polymer particles. Among them, 4 to 6 parts of liquid crystal polymer resin modifier are weighed in parts by weight and blended with 94 to 95 parts of liquid crystal polymer resin, and the liquid crystal polymer resin is selected from Celanes A950, Ticona A950 or Blonde R8000 or a combination thereof. The screw zone temperature is 180°C to 295°C. The low temperature range is 10-35°C, and the speed of the stirring shaft of the stirrer is 50-70 rpm. Among them, the screw extruder in this embodiment is preferably a twin-screw extruder.

[0048] Example 1

[0049] This embodiment provides a method for preparing a liquid crystal polymer film, which comprises the following steps:

[0050] Step 1: Calculated by weight, 0.5 parts of 2,2'-bis(2-oxazoline) and 4.5 parts of polyethylene naphthalate (PEN) are placed in a constant temperature mixer, and mixed at 100°C for 5-20 minutes to obtain a liquid crystal polymer modifier, wherein the speed of the constant temperature mixer is 3000r / min.

[0051] Step 2: Copolymerize and stir evenly 5 parts of liquid crystal polymer modifier and 95 parts of liquid crystal polymer resin (LCP resin) at 25°C and 60 rpm before placing them in a screw extruder, and then melt-plasticize and extrude granulate them through a screw extruder to obtain liquid crystal polymer particles, namely LCP-(PEN-0.5M). The temperatures of the screw zones in the screw extruder are 200°C, 250°C, 290°C, 290°C, 290°C, 290°C, 290°C, 290°C, 290°C, 290°C, the feed speed is 10r / min, and the screw speed is 100r / min. The above-mentioned copolymerization and stirring step can be carried out by placing the liquid crystal polymer modifier and the liquid crystal polymer resin (LCP resin) in a stirring container and stirring them at a low speed.

[0052] Step 3: After drying the liquid crystal polymer particles, the obtained particles are blown into a film by a film blowing machine, and the temperature of each section of the film blowing machine is set to 260°C, 280°C, 300°C, 300°C, 300°C, 300°C, 300°C, 305°C, 305°C, 305°C, 305°C. The screw speed is 10rpm, the metering pump speed is 5rpm, and the traction speed is 3m / min. Under this condition, a liquid crystal polymer film can be obtained.

[0053] Example 2

[0054] This embodiment provides a method for preparing a liquid crystal polymer film, which comprises the following steps:

[0055] Step 1: Calculated by weight, 0.8 parts of 2,2'-bis(2-oxazoline) and 4.5 parts of polyethylene naphthalate (PEN) are placed in a constant temperature mixer, and mixed at 100°C for 5-20 minutes to obtain a liquid crystal polymer modifier, wherein the speed of the constant temperature mixer is 3000r / min.

[0056] Step 2: Copolymerize and stir evenly 5 parts of liquid crystal polymer modifier and 95 parts of liquid crystal polymer resin (LCP resin) at 25°C and 60 rpm before placing them in a screw extruder, and then melt-plasticize and extrude granulate them through a screw extruder to obtain liquid crystal polymer particles, namely LCP-(PEN-1.5M). The temperatures of the screw zones in the screw extruder are 200°C, 250°C, 290°C, 290°C, 290°C, 290°C, 290°C, 290°C, 290°C, 290°C, the feed speed is 10r / min, and the screw speed is 100r / min. The above-mentioned copolymerization and stirring step can be carried out by placing the liquid crystal polymer modifier and the liquid crystal polymer resin (LCP resin) in a stirring container and stirring them at a low speed.

[0057] Step 3: After drying the liquid crystal polymer particles, the obtained particles are blown into a film by a film blowing machine, and the temperature of each section of the film blowing machine is set to 260°C, 280°C, 300°C, 300°C, 300°C, 300°C, 300°C, 305°C, 305°C, 305°C, 305°C. The screw speed is 10rpm, the metering pump speed is 5rpm, and the traction speed is 3m / min. Under this condition, a liquid crystal polymer film can be obtained.

[0058] Example 3

[0059] This embodiment provides a method for preparing a liquid crystal polymer film, which comprises the following steps:

[0060] Step 1: Calculated by weight, 1.1 parts of 2,2'-bis(2-oxazoline) and 4.5 parts of polyethylene naphthalate (PEN) are placed in a constant temperature mixer, and mixed at 100°C for 5-20 minutes to obtain a liquid crystal polymer modifier, wherein the speed of the constant temperature mixer is 3000r / min.

[0061] Step 2: Copolymerize and stir evenly 5 parts of liquid crystal polymer modifier and 95 parts of liquid crystal polymer resin (LCP resin) at 25°C and 60 rpm before placing them in a screw extruder, and then melt-plasticize and extrude granulate them through a screw extruder to obtain liquid crystal polymer particles, namely LCP-(PEN-1.5M). The temperatures of the screw zones in the screw extruder are 200°C, 250°C, 290°C, 290°C, 290°C, 290°C, 290°C, 290°C, 290°C, 290°C, the feed speed is 10r / min, and the screw speed is 100r / min. The above-mentioned copolymerization and stirring step can be carried out by placing the liquid crystal polymer modifier and the liquid crystal polymer resin (LCP resin) in a stirring container and stirring them at a low speed.

[0062] Step 3: After drying the liquid crystal polymer particles, the obtained particles are blown into a film by a film blowing machine, and the temperature of each section of the film blowing machine is set to 260°C, 280°C, 300°C, 300°C, 300°C, 300°C, 300°C, 305°C, 305°C, 305°C, 305°C. The screw speed is 10rpm, the metering pump speed is 5rpm, and the traction speed is 3m / min. Under this condition, a liquid crystal polymer film can be obtained.

[0063] Example 4

[0064] This embodiment provides a method for preparing a liquid crystal polymer film, which comprises the following steps:

[0065] Step 1: Calculated by weight, 0.5 parts of 2,2'-(1,4-phenylene)bis(2-oxazoline) and 4.5 parts of polyethylene naphthalate (PEN) are placed in a constant temperature mixer, and mixed at 100°C for 5-20 minutes to obtain a liquid crystal polymer modifier, wherein the speed of the constant temperature mixer is 3000r / min.

[0066] Step 2: Copolymerize and stir evenly 5 parts of liquid crystal polymer modifier and 95 parts of liquid crystal polymer resin (LCP resin) at 25°C and 60 rpm before placing them in a screw extruder, and then melt-plasticize and extrude granulate them through a screw extruder to obtain liquid crystal polymer particles, namely LCP-(PEN-1.5M). The temperatures of the screw zones in the screw extruder are 200°C, 250°C, 290°C, 290°C, 290°C, 290°C, 290°C, 290°C, 290°C, 290°C, the feed speed is 10r / min, and the screw speed is 100r / min. The above-mentioned copolymerization and stirring step can be carried out by placing the liquid crystal polymer modifier and the liquid crystal polymer resin (LCP resin) in a stirring container and stirring them at a low speed.

[0067] Step 3: After drying the liquid crystal polymer particles, the obtained particles are blown into a film by a film blowing machine, and the temperature of each section of the film blowing machine is set to 260°C, 280°C, 300°C, 300°C, 300°C, 300°C, 300°C, 305°C, 305°C, 305°C, 305°C. The screw speed is 10rpm, the metering pump speed is 5rpm, and the traction speed is 3m / min. Under this condition, a liquid crystal polymer film can be obtained.

[0068] Example 5

[0069] This embodiment provides a method for preparing a liquid crystal polymer film, which comprises the following steps:

[0070] Step 1: Calculated by weight, 0.8 parts of 2,2'-(1,4-phenylene)bis(2-oxazoline) and 4.5 parts of polyethylene naphthalate (PEN) are placed in a constant temperature mixer, and mixed at 100°C for 5-20 minutes to obtain a liquid crystal polymer modifier, wherein the speed of the constant temperature mixer is 3000r / min.

[0071] Step 2: 5 parts of liquid crystal polymer modifier and 95 parts of liquid crystal polymer resin (LCP resin) are copolymerized and stirred uniformly at 25°C and 60 rpm before being placed in a screw extruder, and then melt-plasticized and extruded into granules through a screw extruder to obtain liquid crystal polymer particles, namely LCP-(PEN-1.5M). The temperatures of the screw zones in the screw extruder are 200°C, 250°C, 290°C, 290°C, 290°C, 290°C, 290°C, 290°C, 290°C, 290°C, the feed speed is 10r / min, and the screw speed is 100r / min.

[0072] Step 3: After drying the liquid crystal polymer particles, the obtained particles are blown into a film by a film blowing machine, and the temperature of each section of the film blowing machine is set to 260°C, 280°C, 300°C, 300°C, 300°C, 300°C, 300°C, 305°C, 305°C, 305°C, 305°C. The screw speed is 10rpm, the metering pump speed is 5rpm, and the traction speed is 3m / min. Under this condition, a liquid crystal polymer film can be obtained.

[0073] Example 6

[0074] This embodiment provides a method for preparing a liquid crystal polymer film, which comprises the following steps:

[0075] Step 1: Calculated by weight, 1.1 parts of 2,2'-(1,4-phenylene)bis(2-oxazoline) and 4.5 parts of polyethylene naphthalate (PEN) are placed in a constant temperature mixer, and mixed at 100°C for 5-20 minutes to obtain a liquid crystal polymer modifier, wherein the speed of the constant temperature mixer is 3000r / min.

[0076] Step 2: 5 parts of liquid crystal polymer modifier and 95 parts of liquid crystal polymer resin (LCP resin) are copolymerized and stirred uniformly at 25°C and 60 rpm before being placed in a screw extruder, and then melt-plasticized and extruded into granules through a screw extruder to obtain liquid crystal polymer particles, namely LCP-(PEN-1.5M). The temperatures of the screw zones in the screw extruder are 200°C, 250°C, 290°C, 290°C, 290°C, 290°C, 290°C, 290°C, 290°C, 290°C, the feed speed is 10r / min, and the screw speed is 100r / min.

[0077] Step 3: After drying the liquid crystal polymer particles, the obtained particles are blown into a film by a film blowing machine, and the temperature of each section of the film blowing machine is set to 260°C, 280°C, 300°C, 300°C, 300°C, 300°C, 300°C, 305°C, 305°C, 305°C, 305°C. The screw speed is 10rpm, the metering pump speed is 5rpm, and the traction speed is 3m / min. Under this condition, a liquid crystal polymer film can be obtained.

[0078] Comparative Example 1

[0079] This comparative example provides a method for preparing a liquid crystal polymer film, which comprises the following steps:

[0080] Step 1: Place the liquid crystal polymer resin (LCP resin) directly in front of the screw extruder, first copolymerize and stir evenly at 25°C and 60 rpm, then melt-plasticize and extrude granules through the screw extruder to obtain liquid crystal polymer particles. The temperatures of the screw zones in the screw extruder are 200°C, 250°C, 290°C, 290°C, 290°C, 290°C, 290°C, 290°C, 290°C, 290°C, the feed speed is 10r / min, and the screw speed is 100r / min.

[0081] Step 2: After drying the liquid crystal polymer particles, the obtained particles are blown into a film by a film blowing machine, and the temperatures of each section of the film blowing machine are set to 260°C, 280°C, 300°C, 300°C, 300°C, 300°C, 300°C, 305°C, 305°C, 305°C, 305°C. The screw speed is 10rpm, the metering pump speed is 5rpm, and the traction speed is 3m / min. Under this condition, a liquid crystal polymer film can be obtained.

[0082] Comparative Example 2

[0083] This comparative example provides a method for preparing a liquid crystal polymer film, which comprises the following steps:

[0084] Step 1: Calculated by weight, 0.5 parts of 2,2'-bis(2-oxazoline) and 100 parts of liquid crystal polymer resin (LCP resin) are copolymerized and stirred uniformly at 25°C and 60 rpm before being placed in a screw extruder, and then melt-plasticized and extruded into granules through a screw extruder to obtain liquid crystal polymer particles. The temperatures of the screw zones in the screw extruder are 200°C, 250°C, 290°C, 290°C, 290°C, 290°C, 290°C, 290°C, 290°C, 290°C, 290°C, the feed speed is 10r / min, and the screw speed is 100r / min.

[0085] Step 2: After drying the liquid crystal polymer particles, the obtained particles are blown into a film by a film blowing machine, and the temperatures of each section of the film blowing machine are set to 260°C, 280°C, 300°C, 300°C, 300°C, 300°C, 300°C, 305°C, 305°C, 305°C, 305°C. The screw speed is 10rpm, the metering pump speed is 5rpm, and the traction speed is 3m / min. Under this condition, a liquid crystal polymer film can be obtained.

[0086] Comparative Example 3

[0087] This comparative example provides a method for preparing a liquid crystal polymer film, which comprises the following steps:

[0088] Step 1: Calculated by weight, 5 parts of 2,2'-bis(2-oxazoline) and 95 parts of liquid crystal polymer resin (LCP resin) are copolymerized and stirred uniformly at 25°C and 60 rpm before being placed in a screw extruder, and then melt-plasticized and extruded into granules through a screw extruder to obtain liquid crystal polymer particles. The temperatures of the screw zones in the screw extruder are 200°C, 250°C, 290°C, 290°C, 290°C, 290°C, 290°C, 290°C, 290°C, 290°C, 290°C, the feed speed is 10r / min, and the screw speed is 100r / min.

[0089] Step 2: After drying the liquid crystal polymer particles, the obtained particles are blown into a film by a film blowing machine, and the temperatures of each section of the film blowing machine are set to 260°C, 280°C, 300°C, 300°C, 300°C, 300°C, 300°C, 305°C, 305°C, 305°C, 305°C. The screw speed is 10rpm, the metering pump speed is 5rpm, and the traction speed is 3m / min. Under this condition, a liquid crystal polymer film can be obtained.

[0090] Comparative Example 4

[0091] This embodiment provides a method for preparing a liquid crystal polymer film, which comprises the following steps:

[0092] Step 1: Calculated by weight, 0.5 parts of 2,2'-bis(2-oxazoline) and 4.5 parts of polyethylene naphthalate (PEN), and 95 parts of liquid crystal polymer resin (LCP resin) are first copolymerized and stirred at 25°C and 60 rpm before being placed in a screw extruder, and then melt-plasticized and extruded into granules through a screw extruder to obtain liquid crystal polymer particles. Among them, the temperatures of the screw zones in the screw extruder are 200°C, 250°C, 290°C, 290°C, 290°C, 290°C, 290°C, 290°C, 290°C, 290°C, 290°C, the feed speed is 10r / min, and the screw speed is 100r / min.

[0093] Step 2: After drying the liquid crystal polymer particles, the obtained particles are blown into a film by a film blowing machine, and the temperatures of each section of the film blowing machine are set to 260°C, 280°C, 300°C, 300°C, 300°C, 300°C, 300°C, 305°C, 305°C, 305°C, 305°C. The screw speed is 10rpm, the metering pump speed is 5rpm, and the traction speed is 3m / min. Under this condition, a liquid crystal polymer film can be obtained.

[0094] Comparative Example 5

[0095] Step 1: Calculated by weight, 5 parts of polyethylene naphthalate (PEN) are placed in a constant temperature mixer, and mixed at 100° C. for 5-20 minutes to obtain a liquid crystal polymer modifier, wherein the rotation speed of the constant temperature mixer is 3000 r / min.

[0096] Step 2: 5 parts of liquid crystal polymer modifier and 95 parts of liquid crystal polymer resin (LCP resin) are placed in a screw extruder, first copolymerized and stirred at 25°C and 60 rpm, and then melt-plasticized and extruded into granules by a screw extruder to obtain liquid crystal polymer particles, wherein the temperatures of the screw zones of the screw machine are 200°C, 250°C, 290°C, 290°C, 290°C, 290°C, 290°C, 290°C, 290°C, and 290°C, wherein the speed of the constant temperature mixer is 3000r / min. The feeding speed is 10r / min, the screw speed is 100r / min, and the mixture is melt-plasticized and granulated to obtain modified LCP particles, i.e., the modified LCP material. After drying the obtained LCP pellets, a film blowing machine is used for film blowing.

[0097] Step 3: After drying the liquid crystal polymer particles, the obtained particles are blown into a film by a film blowing machine, and the temperature of each section of the film blowing machine is set to 260°C, 280°C, 300°C, 300°C, 300°C, 300°C, 300°C, 305°C, 305°C, 305°C, 305°C. The screw speed is 10rpm, the metering pump speed is 5rpm, and the traction speed is 3m / min. Under this condition, a liquid crystal polymer film can be obtained.

[0098] Related performance tests of liquid crystal polymer particles during granulation

[0099] Melt index test equipment specifications: NETZSCH melt index tester CEAST MF20 MF30;

[0100] Specifications of granulation equipment: Ruiya twin-screw extruder T35.

[0101] Record the current size and pressure before the extrusion filter during the granulation process of the screw extruder extruding the liquid crystal polymer particles, and test the melt index of the material. The melt index can indirectly reflect the melt strength of the liquid crystal polymer particles. The lower the melt index, the higher the melt strength. Use a rotational rheometer to test the change of the complex viscosity of the material with the shear frequency; the melt index is inversely proportional to the viscosity of the melt, the extrusion current size, and the pressure before the extrusion filter.

[0102] The test characteristics of the embodiments and comparative examples are as follows:

[0103] Table 1 shows the test results of relevant material properties in the process of preparing liquid crystal polymer particles in Examples 1-5 and Comparative Examples 1-6

[0104]

[0105]

[0106]

[0107] From the analysis of the experimental results in Table 1 above, it can be seen that by comparing the results of Example 1 and Comparative Example 4, it can be seen that the pre-blending and heating treatment of 2,2'-bis(2-oxazoline) and polyethylene naphthalate (PEN) is compared with not pre-blending and then mixed with a liquid crystal polymer resin to prepare liquid crystal polymer particles. The melt index is reduced from 47.8 g / 10min to 29.4 g / 10min, thereby greatly reducing the melt index. At the same time, the extrusion pressure is significantly increased from 0.8 MPa to 1.4 MPa. The results show that the pre-blending method can better improve the melt strength of the modified LCP and improve the melt viscosity.

[0108] At the same time, by comparing the results of Example 1 and Comparative Examples 1 to 3, it can be seen that compared with the liquid crystal polymer particles prepared by unmodified treatment and the method of adding 2,2'-bis(2-oxazoline) or PEN alone, the melt index of the modified liquid crystal polymer particles prepared by pre-blending and heating 2,2'-bis(2-oxazoline) and PEN can be greatly reduced from 66.4 g / 10min to 29.4 g / 10min, and the extrusion pressure is significantly increased from 0.4 MPa to 1.4 MPa.

[0109] It can be seen from the results of Comparative Examples 3 and 5 that the melt index of the liquid crystal polymer particles obtained by pre-blending PEN with the liquid crystal polymer resin and then extruding it through a screw machine is similar to the melt index of the liquid crystal polymer particles extruded through a screw machine after direct blending without pre-blending. This shows that pre-blending of a single plasticizer or compatibilizer with the liquid crystal polymer particles cannot improve the effect of PEN in thickening the liquid crystal polymer resin (LCP).

[0110] It can be seen from the results of Examples 1, 2 and 3 that further increasing the proportion of liquid crystal polymer resin modifiers containing oxygen functional groups, such as 2,2'-bis(2-oxazoline) as a bisoxazoline-based compound in the liquid crystal polymer modifier can significantly improve the melt strength and melt viscosity of the liquid crystal polymer particles.

[0111] It can be seen from the results of Examples 1 to 3 and Examples 4 to 6 that 2,2'-(1,4-phenylene)bis(2-oxazoline) can be used as a compatibilizer instead of 2,2'-bis(2-oxazoline) for pre-blending treatment, which can also improve the melt strength and melt viscosity of the liquid crystal polymer particles, but in terms of effect, 2,2'-bis(2-oxazoline) is better.

[0112] In addition, if Figure 1 As shown, it further reflects the viscosity change of each embodiment. Only a small amount of modifier is added, for example, 0.5 parts of 2,2'-bis(2-oxazoline) is used as a modifier for liquid crystal polymer, which has almost no effect on the viscosity of LCP, which is consistent with the result of melt index. If 5% of PEN is added to the modifier of liquid crystal polymer by pre-blending, the melt viscosity of LCP will be slightly increased. This is because PEN destroys the rigidity of LCP molecular chain. When the two exist at the same time, a small amount of functional groups in 2,2'-bis(2-oxazoline) makes LCP react with PEN, so that the two are chemically bonded, thereby further improving the degree of disentanglement of LCP under shear, and effectively improving the melt strength of LCP during melt extrusion. In addition, pre-blending effectively improves the dispersion mixing effect between 2,2'-bis(2-oxazoline) and PEN, thereby further improving the viscosity and melt strength of LCP blends.

[0113] In addition, according to the above Figures 4 to 6 , and the data comparison of the above Table 1 shows that if the compatibilizer is not added to the liquid crystal polymer modifier, it is easy to cause phase separation during the film blowing process due to the poor compatibility of LCP and PEN, which can easily cause obvious uneven plasticization on the film surface. However, after adding a small amount of a bifunctional compatibilizer, such as a bis-oxazoline compound composed of 2,2'-bis(2-oxazoline) or 2,2'-(1,4-phenylene)bis(2-oxazoline), the compatibility of LCP and PEN can be significantly improved, and the melt strength is further improved, so that the surface of the prepared liquid crystal polymer film is smooth and the bubble size is larger.

[0114] In addition, from Figure 5 and Figure 6It can be seen from the comparison that increasing the addition amount of 2,2'-bis(2-oxazoline) in the liquid crystal polymer modifier will further increase the melt strength of LCP, thereby increasing the blowing point and forming larger film bubbles. At the same time, the film surface is smooth and has no crystal points, which indicates that the liquid crystal polymer modifier has good dispersion in LCP.

[0115] from Figure 7 and Figure 8 It can be seen from the comparison that when the addition amount of 2,2'-bis(2-oxazoline) reaches 1.1 parts, the smoothness of the film surface is worse than before, and there are more crystal points. This is because the LCP resin after the modification has gelation phenomenon. This may be due to the excessive amount of compatibilizer in the liquid crystal polymer modifier, which causes PEN to extend the chain during pre-blending, and then agglomerate in LCP to cause phase separation, resulting in obvious roughness on the film surface. It can be seen that in the liquid crystal polymer modifier, in the case of 4.5 parts of tackifier, the addition amount of solubilizer, such as the addition amount of bisoxazoline compound, is preferably controlled at 0.5-0.8. In addition, it can be seen from Example 2 that within this range, the melt index of the liquid crystal polymer particles can be reduced to 18.2g / 10min, and at the same time, the extrusion pressure is significantly increased from 0.8Mpa to 1.7Mpa, and the prepared liquid crystal polymer film has good film continuity and a smooth surface.

[0116] The embodiment of the present invention adopts a pre-blending method, wherein a compatibilizer containing an active group, such as a carboxyl group or a hydroxyl group, and / or an oxazoline group, is pre-blended with a tackifier in a high-speed mixer below the reaction temperature, and the dispersion and mixing effect between the compatibilizer and PEN is effectively improved. At the same time, it can also prevent the compatibilizer from being unevenly dispersed in the PEN and LCP matrices, resulting in serious gelation. During the melt reaction, the active groups on the compatibilizer can better react with the tackifier and the oxygen-containing functional groups such as the carboxyl group or the hydroxyl group at the end of the resin to produce a branching reaction, thereby solving the problems of poor compatibility and uneven dispersion of the tackifier and the liquid crystal polymer resin when a small amount of compatibilizer is added, and at the same time, the viscosity and melt strength of the liquid crystal polymer particles are significantly improved, and the stability and smoothness of the liquid crystal polymer film after the modification are achieved. In particular, the embodiments of the present invention preferably use a compatibilizer containing two oxazolines, which can react with the hydroxyl or carboxyl groups at the ends of LCP and PEN. At the same time, without seriously destroying the liquid crystal properties of LCP, appropriate addition can solve the problems of poor compatibility and uneven dispersion of the tackifier and the matrix resin. At the same time, the bifunctional group can also couple the LCP to increase the molecular weight, thereby increasing its melt strength and viscosity, and reducing its reaction with the liquid crystal polymer resin (LCP). Figure 2As shown, the probability of forming a brush-type polymer molecular brush is reduced, or the number of polymer molecular brushes is greatly reduced, thereby better avoiding the destruction of the liquid crystallinity of LCP while improving the degree of disentanglement of LCP at high shear rate, thereby effectively improving the melt strength during extrusion.

[0117] The above are only preferred embodiments of the present application and do not have any limiting effect on the present application. Any technical personnel in the relevant technical field, without departing from the scope of the technical solution of the present application, may make any form of equivalent replacement or modification to the technical solution and technical content disclosed in the present application, which shall be deemed as the content of the technical solution of the present application and still fall within the protection scope of the present application.

Claims

1. A method for preparing liquid crystal polymer particles, characterized in that: The following steps are involved: The tackifier and the compatibilizer are pre-heated and mixed to obtain a liquid crystal polymer resin modifier, wherein the tackifier includes at least an oxygen-containing functional group; the compatibilizer contains at least a plurality of active groups, and the oxygen functional group contained in the compatibilizer is used to form a coupling reaction with the oxygen-containing functional group; The liquid crystal polymer resin modifier is blended with the liquid crystal polymer resin and then melt-extruded through a screw extruder to form liquid crystal polymer particles.

2. The method for preparing liquid crystal polymer particles according to claim 1, characterized in that: The step of pre-heating and blending the tackifier and the compatibilizer to obtain the liquid crystal polymer resin modifier comprises: The tackifier and the compatibilizer are blended in a high-speed mixer at a temperature of 80 to 150° C. and a rotation speed of 3000 to 5000 rpm to obtain the liquid crystal polymer resin modifier.

3. The method for preparing liquid crystal polymer particles according to claim 1, characterized in that: The step of blending the liquid crystal polymer resin modifier with the liquid crystal polymer resin and then extruding the mixture through a screw extruder to form liquid crystal polymer particles comprises: The liquid crystal polymer resin modifier and the liquid crystal polymer resin are blended and stirred, and then melt-extruded through a screw extruder, wherein the temperature of the screw extrusion zone is 200-350° C., the screw speed of the screw extruder is 100-150 rpm; and the terminal temperature of the screw extrusion zone is greater than or equal to 295° C.

4. The method for preparing liquid crystal polymer particles according to claim 1, characterized in that: The mass ratio of the liquid crystal polymer resin modifier to the liquid crystal polymer resin before blending is 5:95; And / or, the mass ratio of the tackifier to the compatibilizer is (0.5-1.1):4.

5.

5. The method for preparing liquid crystal polymer particles according to claim 1, characterized in that: The mass percentage of the tackifier in the liquid crystal polymer particles is 1%-20%.

6. The method for preparing liquid crystal polymer particles according to claim 5, characterized in that: The mass percentage of the tackifier in the liquid crystal polymer particles is 3%-6%.

7. The method for preparing liquid crystal polymer particles according to claim 1, characterized in that: The mass percentage of the compatibilizer in the liquid crystal polymer particles is 0.1%-3%.

8. The method for preparing liquid crystal polymer particles according to claim 5, characterized in that: The mass percentage of the compatibilizer in the liquid crystal polymer particles is 0.45%-1%.

9. The method for preparing liquid crystal polymer particles according to claim 1, characterized in that: The oxygen-containing functional groups at least include: carboxyl groups; and / or, hydroxyl group; The active groups at least include: oxazoline groups; And / or, the active group is a bifunctional group.

10. The method for preparing liquid crystal polymer particles according to claim 1, characterized in that: The tackifier includes any one or a combination of two or more of polyarylate, polyetheretherketone, polyimide, polysulfone, polyphenylene oxide, polycarbonate, polyethylene naphthalate and polyethylene terephthalate; And / or, the compatibilizer includes any one of diisocyanate, maleic anhydride, bis-oxazoline compounds, and diepoxy compounds, or a combination thereof.

11. The method for preparing liquid crystal polymer particles according to claim 10, characterized in that: The compatibilizer is 2,2'-bis(2-oxazoline) or 2,2'-(1,4-phenylene)bis(2-oxazoline); And / or, the liquid crystal polymer resin is one of A950 and R8000, or a mixture of two or more thereof.

12. A liquid crystal polymer particle, characterized in that: The liquid crystal polymer particles are prepared by the method for preparing the liquid crystal polymer particles according to any one of claims 1 to 11.

13. A method for preparing a liquid crystal polymer film, characterized in that: The liquid crystal polymer particles according to claim 12 are processed by a film blowing method.

14. A liquid crystal polymer film, characterized in that: The method for preparing the liquid crystal polymer film according to claim 13 is used for preparation.

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