Oiling agent for preparing liquid crystal polyarylester fiber and preparation method and application of liquid crystal polyarylester fiber

Abstract

The invention belongs to the technical field of liquid crystal polyarylester fiber preparation, and particularly relates to an oiling agent for liquid crystal polyarylester fiber preparation and a liquid crystal polyarylester fiber preparation method and application. The oiling agent is mainly prepared from phosphate salt with a specific chain length and silicone oil, can be applied after a melt extrusion process of liquid crystal polyarylate melt spinning and before a drafting process, and does not need to be cleaned in a heat treatment process and after the heat treatment process. The oiling agent is used for melt spinning preparation of liquid crystal polyarylester fibers, yarn scattering, yarn floating and fuzzing / end breaking caused by static electricity and fiber bonding caused by decomposition of the oiling agent in heat treatment can be reduced, cleaning before and after heat treatment is not needed, the performance of a finished product is improved, the production process is simplified, and popularization of the industrial production process is facilitated.

Description

Technical Field

[0001] The invention belongs to the technical field of liquid crystal polyarylate fiber preparation, and particularly relates to an oil agent for preparing liquid crystal polyarylate fiber, a preparation method of the liquid crystal polyarylate fiber and application thereof. Background Art

[0002] Liquid crystal polyarylate, also known as liquid crystal aromatic polyester (LCP), is widely used in the field of high-performance fibers due to its excellent high-temperature resistance, mechanical strength and dimensional stability. However, there are two major technical bottlenecks in the melt spinning and post-processing processes of LCP fibers: First, the LCP spinning stage has poor bundling and high spinning winding speed. Its molecular chains are highly oriented and the surface is smooth, resulting in serious static electricity accumulation between LCP fibers, prone to loose fibers, floating fibers, fuzzing and even broken ends, which directly affects the spinning efficiency and fiber uniformity; second, the post-spinning heat treatment stage of LCP (i.e., the subsequent heat treatment of the spun fibers, also known as post-solid-phase polymerization) requires long-term heat treatment at high temperatures. Traditional oils decompose at high temperatures to produce sticky residues, which leads to adhesion between fibers and affects the mechanical properties and processing stability of the finished LCP fibers. The preparation of LCP fibers requires high-temperature heat treatment (post-solid-phase polymerization). The temperature and time are similar. Usually the heat treatment temperature is close to but slightly lower than the melting point of LCP. The main purpose is to increase viscosity through solid-phase polymerization, enlarge the molecular chain, and improve various physical properties such as strength.

[0003] For these reasons, the development of spinning and solid-phase polymerization oils for LCP fiber melt spinning has become an important research and development direction. Patent document CN119843396A discloses a highly wear-resistant nanoparticle composite polyester fiber spinning oil, and CN119843394A discloses a highly wettable special-shaped polyester fiber spinning oil. While these two approaches focus on different technical issues, both utilize conventional antistatic agents and lack improvements in antistatic and anti-adhesive properties of LCP.

[0004] To date, there has been no solution to overcome the problems of loose fibers, floating fibers, and fuzz / breakage caused by static electricity during LCP spinning, as well as the problem of inter-fiber bonding caused by the decomposition of oils during heat treatment, by adding specific additives during the melt spinning process. Summary of the Invention

[0005] To address the above-mentioned issues, the present invention aims to provide an oil for preparing liquid crystal polyarylate fibers, as well as a method for preparing and using liquid crystal polyarylate fibers. By using this oil in the spinning and heat treatment processes of liquid crystal polyarylate fibers, it can reduce loose fibers, drifting fibers, fuzzing / breakage caused by static electricity, as well as inter-fiber bonding caused by oil decomposition during heat treatment, and significantly improve the mechanical properties of liquid crystal polyarylate fibers. The technical solutions of the present invention are as follows:

[0006] First, the present invention provides an oil agent for preparing liquid crystal polyarylate fibers, which contains phosphate salt, silicone oil and water; the weight ratio of phosphate salt to silicone oil in the oil agent is (1-4):(1-4).

[0007] Preferably, the phosphate salt is an alkyl phosphate salt and / or an alkyl polyoxyethylene ether phosphate salt, wherein the number of carbon atoms in the alkyl chain of the alkyl phosphate salt is a natural number of 8 to 24, the number of carbon atoms in the alkyl chain structure of the alkyl polyoxyethylene ether phosphate salt is a natural number of 8 to 24, and the number of carbon atoms in the polyoxyethylene ether structure is a natural number of 4 to 24. The polyoxyethylene ether structure is generally represented by the ethyleneoxy group (ethylene oxide, chemical formula C2H4O) of the ethyleneoxy chain. Therefore, it can also be understood that the EO number of the alkyl polyoxyethylene ether phosphate salt is a natural number of 2 to 12.

[0008] Preferably, the silicone oil is selected from one or more of methyl silicone oil, hydroxy silicone oil, hydrogen silicone oil, and silicone polyether.

[0009] Preferably, the viscosity of the silicone oil is 10 cs to 1000 cs.

[0010] Preferably, the phosphate salt is selected from one or more of potassium phosphate, sodium phosphate, and amine phosphate.

[0011] Preferably, the oil further contains an emulsifier.

[0012] Obviously, silicone oil can be formulated with an emulsifier and water to form a silicone oil emulsion, and silicone oil emulsions are already available in large quantities on the market. When preparing an emulsifier-containing oil of the present invention, a commercially available silicone oil emulsion can be used or a silicone oil emulsion can be prepared according to conventional silicone oil emulsion preparation methods, followed by the addition of a phosphate salt and the balance of water. When preparing an emulsifier-free oil of the present invention, the required materials can be conventionally mixed and stirred to complete the preparation. The emulsifiers include, but are not limited to, emulsifier 1305, emulsifier 1307, or mixtures thereof.

[0013] The present invention also provides for the use of the aforementioned oil as a common oil for both the melt spinning and post-spinning heat treatment processes of liquid crystal polyarylate fibers. By applying a common oil for both melt spinning and post-spinning heat treatment (no cleaning or removal of the oil is required between the heat treatment and melt spinning processes), the mechanical properties of liquid crystal polyarylate fibers can be improved, while problems such as loose fibers, drifting fibers, and fuzzing / breakage caused by static electricity during the spinning process, as well as inter-fiber adhesion caused by oil decomposition during the heat treatment, can be reduced. Cleaning before and after the heat treatment is also eliminated.

[0014] The present invention also provides a melt spinning method for preparing liquid crystal polyarylate fibers, comprising the following steps:

[0015] Liquid crystal polyarylate chips are melt-extruded using a single-screw extruder with a high-temperature melt temperature of 280°C to 360°C. The filaments are extruded through a spinneret and oiled before drawing with an oiling rate of 0.5% to 2%. After winding on a bobbin, they are subjected to a high-temperature heat treatment at a temperature of 250°C to 320°C.

[0016] The oil agent is the aforementioned oil agent containing phosphate salt, silicone oil and water, and an emulsifier may be added.

[0017] The technology of the present invention has the following beneficial effects

[0018] (1) The oil for preparing the liquid crystal polyarylate fiber of the present invention can be applied after the melt extrusion step and before the drawing step of the liquid crystal polyarylate melt spinning process, and does not require cleaning before the heat treatment step, thereby simplifying the preparation process of the liquid crystal polyarylate fiber.

[0019] (2) The oil agent for preparing the liquid crystal polyarylate fiber of the present invention can still exert a good anti-adhesion effect even after undergoing a heat treatment process within a specific ratio range, thereby reducing problems such as loose fibers, floating fibers, and fuzz / breakage caused by static electricity during the spinning process through anti-static treatment, and can also reduce inter-fiber adhesion caused by the decomposition of the oil agent during heat treatment.

[0020] (3) The oil for preparing the liquid crystal polyarylate fiber of the present invention can be used as a common oil for two processes without reducing or even improving the mechanical properties of the liquid crystal polyarylate fiber. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a scanning electron microscope image of the liquid crystal polyarylate fiber prepared using the oil of the present invention. DETAILED DESCRIPTION

[0022] The following is a detailed description of the technical ideas, solutions, effects, etc. of the present invention through specific examples. The main raw material sources used in the following examples are as follows: phosphate raw materials are sourced from Jiangsu Hai'an Petrochemical Plant (hereinafter referred to as Hai'an Petrochemical) and Yichang Mingya New Materials Technology Co., Ltd. (hereinafter referred to as Yichang Mingya); silicone oil is sourced from Jiangxi Lanxing Xinghuo Silicone Co., Ltd. (viscosity of 10cs-1000cs). The liquid crystal polyarylate used in the test (Type I and Type II; the liquid crystal polyarylate used in Experimental Example Formula 2 is Type I; the liquid crystal polyarylate used in other experimental examples and comparative examples is Type II) is sourced from Celanese Corporation.

[0023] Example 1 Preparation of Liquid Crystalline Polyarylate Fiber

[0024] Different experimental example oil formulations and comparative example oil formulations were prepared according to the formulations in Table 1.

[0025]

[0026]

[0027] Note: For the formulations in Table 1 that contain an emulsifier, first prepare a silicone oil emulsion by combining the silicone oil with the emulsifier and an appropriate amount of water. Then, add the phosphate ester salt and the remaining amount of water and stir until uniform. When the formulation does not contain an emulsifier, simply mix the required materials according to the formulation and stir until uniform. In the formulations of Experimental Examples 1-8 in Table 1, the mass ratios of phosphate ester salt to silicone oil are: 4:1, 3:1, 3:2, 1:1, 1:1, 2:3, 2:3, and 1:4, respectively. In the formulations of Experimental Examples 1-8 in Table 1, the emulsifier dosage ranges from 0% to 26.7% of the mass of the silicone oil.

[0028] Liquid crystal polyarylate fibers were prepared using the oils prepared according to Table 1. The preparation process was as follows:

[0029] Liquid crystal polyarylate chips are melt-extruded using a single-screw extruder at a high melt temperature of 280°C to 360°C. The filaments are extruded through a spinneret and oiled before drawing at a rate of 0.5% to 2% (w / w, relative to fiber weight). The fibers are then wound on a bobbin at a speed of 1000 to 2000 m / min. Heat treatment is then performed at a temperature of 250 to 320°C for 8 to 12 hours. Within this process parameter range and based on known processing parameters for different liquid crystal polyarylates, the liquid crystal polyarylate fibers prepared using the oil formulation in Table 1 achieved a bundle performance score of 3 points and a lint resistance score of no less than 2.4 points. In certain embodiments, the parameters selected to ensure product comparability are point values ​​and are not to be considered as limiting the scope of protection, but are merely illustrative.

[0030] Example 2 Performance Testing and Evaluation of Liquid Crystalline Polyarylate Fibers

[0031] The liquid crystal polyarylate fibers prepared in Example 1 using the oils in Table 1 under the same conditions were evaluated (for example, a high-temperature melting temperature of 360°C, an oiling rate of 1%, a winding speed of 1500 m / min, a heat treatment temperature of 320°C, and a heat treatment time of 12 h).

[0032] Each rating is based on five samples, and the average of the measurement and evaluation results is taken. The bundling performance rating is evaluated at the same time point during the spinning and drawing process; the hair rating is evaluated by observing the end surface at the same time point after the spinning and drawing is completed and the winding is completed; the anti-adhesion performance rating is evaluated at the same time point after the heat treatment.

[0033] (1) Tensile strength: Take 5 fiber samples of each formulation, 20 cm in length, select the fixture required for the test and install it on the machine. Use an Instron 5965 universal testing machine for testing. The upper fiber fixture should be installed under the sensor and connected to the sensor, and the lower fixture should be installed on the base. Use a little force to place the other end of the fiber sample into the lower fixture and apply pre-tension to the lower end of the sample to straighten the sample. Move the upper fixture upward until the sample strip breaks. Measure each section of fiber five times and take the average value.

[0034] (2) Bundle performance: The performance was evaluated using a graded scoring method. The scoring criteria are shown in Table 2.

[0035] (3) Anti-adhesion performance: The performance was evaluated using a grading method. The scoring criteria are shown in Table 2.

[0036] (4) Severity of hairiness: The severity is assessed using a grading method. The scoring criteria are shown in Table 2.

[0037] Table 2 Rating criteria for liquid crystal polyarylate fibers

[0038] score Cluster performance scoring criteria Anti-adhesion performance scoring standard Silk scoring standards 0 Scattered and floating silk is very serious Very severe adhesion The hair is very serious 1 Severe loose and floating threads Severe adhesion Severe hairiness 2 Scattered and floating silk is more serious Severe adhesion The hair is quite serious 3 There are basically no loose threads or floating threads. There is basically no bonding There is basically no hair

[0039] The results are shown in Table 3. As can be seen from Table 3, the tensile strength of the liquid crystal polyarylate fibers prepared with the oils in the comparative example formulations was lower than that of the liquid crystal polyarylate fibers prepared with the experimental example formulations. While the oil in comparative example formulation 3 improved bundling performance to the same degree as the oil in the experimental example formulation, its improvements in other properties were still far inferior to those of the experimental example formulations.

[0040] Table 3 Performance test and evaluation results of liquid crystal polyarylate fibers prepared by different oils

[0041]

[0042]

[0043] The sample of Experimental Example Formula 1 has good tensile strength and excellent antistatic properties in the spinning and drawing stage (see bundling performance and yarn rating); it may be due to factors such as thermochemical changes caused by heat treatment in the heat treatment stage, resulting in a lower content of available silicone oil or a worse thermal migration effect, so the anti-sticking performance is slightly worse than the oils of Experimental Examples 3-7, but significantly better than the formula of the comparative example.

[0044] The sample from Experimental Example 2 exhibited good tensile strength and excellent antistatic properties during the spinning and drawing stages (see Bunching Performance and Yarn Rating). This was likely due to the hydroxyl silicone oil's poor spreading and penetration during the heat treatment stage, for example, due to the reaction of its hydroxyl groups with some of the carboxyl groups in the polyarylate chips. As a result, its anti-blocking properties were slightly inferior to those of the oils from Experimental Examples 3-7, but significantly superior to those of the comparative examples.

[0045] The sample of Experimental Example Formula 8 has good tensile strength and excellent antistatic properties in the spinning and drawing stage (see bundling performance and hair rating); possibly due to the low amount of phosphate salt used, it is affected by the thermochemical reaction during the heat treatment process and fails to provide better support for the spreading and penetration of silicone oil. Therefore, the anti-adhesion performance is slightly worse than the oils of Experimental Examples 3-7, but significantly better than the formula of the comparative example.

[0046] Samples from Experimental Examples 3, 4, 5, 6, and 7 all exhibited excellent tensile strength, antistatic properties (see Bunching and Filament Rating), and anti-adhesive properties. While the silicone oil viscosity in Samples 3, 5, and 6 differed significantly from that in Samples 4 and 7, all five samples demonstrated excellent anti-adhesive and antistatic properties, demonstrating that silicone oil viscosity is not the primary factor affecting anti-adhesive and antistatic properties.

[0047] Although no emulsifier was used in the preparation of the samples of Experimental Example 4 and 7, their tensile strength, antistatic properties (see Bunching Performance and Filament Rating), and anti-adhesive properties were all good. This shows that the emulsifier and its dosage are not the main factors affecting anti-adhesive and antistatic properties.

[0048] It can be seen that the samples of Experimental Example Formulas 3, 4, 5, 6, and 7, by applying a common oil for both the melt spinning and post-spinning heat treatment processes (i.e., no cleaning or removal of the oil is required between the heat treatment process and the melt spinning process), simultaneously exert excellent antistatic and anti-adhesive effects, playing a beneficial role in both the melt spinning process and the heat treatment process, and also significantly improving the tensile strength of the product. The samples of Experimental Example Formulas 1, 2, and 8 also have good tensile strength, antistatic, and anti-adhesive characteristics.

[0049] The tensile strength and antistatic properties (see Bunching Performance and Filament Rating) of the samples in the comparative example formulations were significantly lower than those in the samples in experimental example formulations 1 to 8. Only the samples in comparative example formulations 2 to 4 achieved an anti-adhesion score of 2 points.

[0050] Figure 1 This is a scanning electron microscope image of a liquid crystal polyarylate fiber (liquid crystal polyarylate is type II, and the preparation process parameters refer to Example 2) prepared using the formula oil of Experimental Example 1 of the present invention. Figure 1 It can be seen that after melt spinning and post-spinning heat treatment, white particles or oval patterns are relatively evenly attached to the fiber surface, which is beneficial to reducing adhesion.

[0051] The above descriptions of the implementation and effects of the present invention are based on specific embodiments. These embodiments are merely exemplary embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications or substitutions made by persons of ordinary skill in the art without requiring creative effort, without departing from the overall technical concept of the present invention, remain within the scope of protection of the present invention.

Claims

1. An oil for preparing liquid crystal polyarylate fibers, characterized in that: The oil contains phosphate salt, silicone oil and water; the weight ratio of phosphate salt to silicone oil in the oil is (1-4):(1-4).

2. The oil for preparing liquid crystal polyarylate fibers according to claim 1, characterized in that: The phosphate salt is an alkyl phosphate salt and / or an alkyl polyoxyethylene ether phosphate salt, the number of carbon atoms in the alkyl chain of the alkyl phosphate salt is a natural number of 8 to 24, the number of carbon atoms in the alkyl chain structure of the alkyl polyoxyethylene ether phosphate salt is a natural number of 8 to 24, and the number of carbon atoms in the polyoxyethylene ether structure is a natural number of 4 to 24.

3. The oil for preparing liquid crystal polyarylate fibers according to claim 1, characterized in that: The silicone oil is selected from one or more of methyl silicone oil, hydroxy silicone oil, hydrogen silicone oil, and silicone polyether.

4. The oil for preparing liquid crystal polyarylate fibers according to claim 2, characterized in that: The viscosity of the silicone oil is 10 cs to 1000 cs.

5. The oil for preparing liquid crystal polyarylate fibers according to claim 1, characterized in that: The phosphate salt is selected from one or more of potassium phosphate, sodium phosphate, and amine phosphate.

6. The oil for preparing liquid crystal polyarylate fibers according to claim 1, characterized in that: The oil further contains an emulsifier.

7. Use of the oil for preparing liquid crystal polyarylate fibers according to any one of claims 1 to 6 as a common oil for both melt spinning and post-spinning heat treatment of liquid crystal polyarylate.

8. A method for preparing liquid crystal polyarylate fibers by melt spinning, characterized in that: The steps include: Liquid crystal polyarylate chips are melt-extruded using a single-screw extruder with a high-temperature melt temperature of 280°C to 360°C. The filaments are extruded through a spinneret and oiled before drawing with an oiling rate of 0.5% to 2%. After winding on a bobbin, they are subjected to a high-temperature heat treatment at a temperature of 250°C to 320°C. The oil contains phosphate salt, silicone oil and water; the weight ratio of phosphate salt to silicone oil in the oil is (1-4):(1-4).

9. The melt spinning method for preparing liquid crystal polyarylate fibers according to claim 8, characterized in that: The phosphate salt is an alkyl phosphate salt and / or an alkyl polyoxyethylene ether phosphate salt, the number of carbon atoms in the alkyl chain of the alkyl phosphate salt is a natural number of 8 to 24, the number of carbon atoms in the alkyl chain structure of the alkyl polyoxyethylene ether phosphate salt is a natural number of 8 to 24, and the number of carbon atoms in the polyoxyethylene ether structure is a natural number of 4 to 24.

10. The melt spinning method for preparing liquid crystal polyarylate fibers according to claim 8, characterized in that: The silicone oil is selected from one or more of methyl silicone oil, hydroxy silicone oil, hydrogen silicone oil, and silicone polyether; and the viscosity of the silicone oil is 10 cs to 1000 cs.

11. The melt spinning method for preparing liquid crystal polyarylate fibers according to claim 8, characterized in that: The phosphate salt is selected from one or more of potassium phosphate, sodium phosphate, and amine phosphate.

12. The melt spinning method for preparing liquid crystal polyarylate fibers according to claim 8, characterized in that: The oil further contains an emulsifier.

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