A high-toughness polyester fiber and its preparation method

Abstract

This invention discloses a high-toughness polyester fiber and its preparation method, thus belonging to the field of fiber preparation technology. The high-toughness polyester fiber is prepared from the following components in parts by weight: 70-80 parts polyethylene terephthalate chips, 5-15 parts toughening agent, 1-5 parts reinforcing filler, 1-3 parts antioxidant stabilizer, and 1-2 parts lubricant. This invention, by using a novel antioxidant stabilizer, not only improves the antioxidant capacity of polyester fiber during high-temperature processing and use, but also protects the performance of the toughening agent and reinforcing filler, effectively improving the mechanical properties of polyester fiber under extreme environments, delaying performance degradation caused by oxidative degradation, and thus extending its service life.

Description

Technical Field

[0001] This invention relates to the field of fiber preparation technology, specifically to a high-toughness polyester and its preparation method. Background Technology

[0002] Polyester fiber, as an important synthetic fiber, is widely used in textiles, industrial cables, and automotive interiors due to its high strength, abrasion resistance, and corrosion resistance. However, with the increasing demands of modern industry on fiber performance, the shortcomings of traditional polyester fiber in terms of toughness have gradually become apparent. Especially in extreme environments, polyester fiber is prone to breakage and performance degradation, which limits its expansion in high-end applications.

[0003] Traditional polyester fiber manufacturing primarily relies on melt spinning of polyethylene terephthalate (PET) chips, but this process suffers from several technical bottlenecks. For example, low intrinsic viscosity or excessively high end carboxyl group content in the chips can lead to poor fiber-forming properties and unstable mechanical properties. Furthermore, the lack of effective toughening and reinforcement methods during fiber processing results in insufficient elongation at break and impact resistance to meet the demands of high-performance applications. These challenges have prompted researchers to explore new material formulations and processing technologies to overcome the inherent limitations in the toughness of existing polyester fibers.

[0004] To address these challenges, the industry has attempted to improve the overall performance of polyester by adding toughening agents, reinforcing fillers, and optimizing spinning processes. For example, the application of toughening agents such as polycaprolactone can significantly improve fiber flexibility, while reinforcing fillers such as nano-calcium carbonate can effectively improve fiber strength and heat resistance. However, these improvements still suffer from insufficient compatibility and poor dispersibility in practical applications, resulting in limited performance enhancements. Therefore, developing a high-toughness polyester fiber with excellent overall performance and reliable manufacturing process has become an important direction for the current polyester industry. Summary of the Invention

[0005] This invention aims to overcome the problems of insufficient toughness of polyester fibers, easy breakage in extreme environments, and poor compatibility of toughening and reinforcing components in existing technologies, and provides a high-toughness polyester and its preparation method. Through optimized material formulation and precisely controlled preparation process, the toughness and weather resistance of polyester are effectively improved to meet the needs of high-end application fields.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A high-toughness polyester is prepared from the following components in parts by weight: 70-80 parts polyethylene terephthalate chips, 5-15 parts toughening agent, 1-5 parts reinforcing filler, 1-3 parts antioxidant stabilizer, and 1-2 parts lubricant.

[0008] The antioxidant stabilizer is a compound represented by Formula 1:

[0009] Formula 1: ;

[0010] In Formula 1, R1 is a substituent, and R1 is selected from any one of methyl, methoxy, tert-butyl, phenyl, and amino.

[0011] Furthermore, the intrinsic viscosity of the polyethylene terephthalate chips is 0.6-0.8 dL / g, and the end carboxyl group content is ≤30 mol / t.

[0012] Furthermore, the toughening agent is polycaprolactone with a number average molecular weight of 5000-20000 g / mol.

[0013] Furthermore, the reinforcing filler is nano-calcium carbonate with a particle size of 50-100 nm.

[0014] Furthermore, the antioxidant stabilizer is any one of the compounds shown in the following structures:

[0015] ;

[0016] ;

[0017] .

[0018] Furthermore, the lubricant is at least one of calcium stearate or ethylene bis-stearamide.

[0019] A method for preparing high-toughness polyester includes the following steps:

[0020] 1) The polyethylene terephthalate (PET) chips were vacuum dried at 80-100℃ for 4-6 hours until the moisture content was ≤0.005%;

[0021] 2) Add the dried polyethylene terephthalate chips, toughening agent, reinforcing filler, antioxidant stabilizer, and lubricant into a high-speed mixer and mix at 900-1100 r / min and 80-100℃ for 15-20 min to obtain the mixture.

[0022] 3) The mixture is fed into a twin-screw extruder and melt-extruded at 260-280°C, and then cut into polyester masterbatch by a pelletizer;

[0023] 4) The polyester masterbatch is fed into a spinning machine and melt-spun at 270-290℃ at a spinning speed of 800-1200m / min. The spun nascent fibers are preheated at 80-100℃, then stretched 2-4 times at 80-140℃, and finally set at 150-170℃ for 5-10s to obtain a high-toughness polyester.

[0024] Furthermore, in step 3), the screw speed of the twin-screw extruder is 200-300 r / min, and the temperatures of each section are as follows: feeding section 200-220℃, compression section 240-260℃, melting section 260-280℃, and die head section 250-270℃.

[0025] Furthermore, in step 4), the spinneret of the spinning machine has a hole diameter of 0.2-0.4 mm and a hole count of 36-72.

[0026] Furthermore, in step 4), the stretching process is carried out in two stages. The first stage stretching ratio is 1.5-2 times and the stretching temperature is 80-90℃; the second stage stretching ratio is 1-2 times and the stretching temperature is 120-140℃.

[0027] The core function of the antioxidant stabilizer in this invention is to inhibit the oxidative degradation of polyester during processing, storage, and use, ensuring the integrity of the polyester molecular structure and thus maintaining its high toughness and other mechanical properties. Firstly, there is the free radical capture mechanism. During high-temperature processing, such as melt extrusion and spinning, or in extreme environments, polyester molecular chains easily generate reactive free radicals such as alkoxy radicals and hydroxyl radicals due to heat and oxygen. These free radicals can trigger chain reactions, leading to molecular chain breakage and a decrease in polyester toughness. The antioxidant stabilizer molecule contains active imino groups, whose hydrogen atoms can combine with reactive free radicals to generate stable nitroxy free radicals and inactive molecular products, terminating the free radical chain reaction and blocking the oxidative degradation chain. Secondly, there is the hydroperoxide decomposition mechanism. Hydroperoxides are generated during polyester oxidation, which easily decompose into more reactive free radicals, accelerating degradation. The antioxidant stabilizer can decompose hydroperoxides into non-free radical products such as alcohols and ketones through proton transfer, preventing them from becoming new sources of oxidation and fundamentally reducing free radical generation.

[0028] This invention systematically solves the technical problems of insufficient toughness, easy breakage, and poor additive compatibility in traditional polyester by leveraging the synergistic effects of its components in the formulation and process. Polyethylene terephthalate (PET) chips, as the matrix, ensure good spinnability and initial strength due to their specific intrinsic viscosity and low carboxyl content. Polycaprolactone toughening agent, as a flexible segment, forms a microphase separation structure with the PET matrix during melt blending. Under external force, it effectively induces crazing and shear banding, absorbing and dispersing impact energy, thereby significantly improving the material's elongation at break and toughness. Nano-calcium carbonate, as rigid particles, is uniformly dispersed in the matrix, acting as a pinning agent to hinder molecular chain slippage, thus enhancing fiber strength and modulus. The key role of the lubricant is to reduce melt viscosity, promote uniform dispersion of nanofillers in the matrix, prevent agglomeration, ensure reinforcing effects, and avoid stress concentration points caused by filler agglomeration, protecting the fiber's toughness. Antioxidant stabilizers effectively inhibit the thermo-oxidative degradation of polyester during high-temperature processing such as extrusion and spinning, as well as subsequent use, by capturing free radicals and decomposing hydroperoxides. This not only protects the integrity of the PET molecular chain and prevents a decrease in toughness due to chain breakage, but more importantly, it protects toughening agents, lubricants, and other organic additives from oxidative failure, ensuring the long-term stability and functional durability of the entire formulation system. This formulation utilizes rigid fillers for reinforcement, flexible toughening agents for toughening, lubricants to improve processing and dispersion, and antioxidants to ensure system stability. The components work synergistically under optimized preparation processes to achieve a balance between high strength and high toughness in polyester.

[0029] Compared with the prior art, the beneficial effects of the present invention are:

[0030] 1. Significantly improves the toughness and impact resistance of polyester: Through optimized material formulation and precise preparation process, this invention achieves a balance between molecular chain flexibility and mechanical strength, enabling polyester to exhibit better tensile strength, elongation at break and impact resistance when subjected to external forces.

[0031] 2. Significantly enhances the aging resistance and long-term stability of polyester: The use of new antioxidant stabilizers not only improves the antioxidant capacity of polyester during high-temperature processing and use, but also protects the performance of toughening agents and reinforcing fillers, effectively improving the mechanical properties of polyester fibers in extreme environments, delaying the performance decline caused by oxidative degradation, and thus extending its service life. Attached Figure Description

[0032] Figure 1 This is the NMR spectrum of the antioxidant stabilizer 1 described in this invention. Detailed Implementation

[0033] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] Preparation Example 1

[0035] Preparation of antioxidant stabilizer 1:

[0036] ;

[0037] CAS number for raw material 1: 101-96-2;

[0038] CAS number for raw material 2: 53086-53-6;

[0039] Under a nitrogen atmosphere, 10.00 g of starting material 1, 10.40 g of starting material 2, 8.72 g of sodium tert-butoxide, 0.41 g of tris(dibenzylacetone)palladium, 0.46 g of tri-tert-butylphosphine, and 100 mL of toluene solution were added to the reaction system. The mixture was stirred until homogeneous, heated to 120 °C, and refluxed for 12 h. After the reaction was complete, the mixture was filtered through diatomaceous earth. The filtrate was cooled to room temperature, washed three times with water, and the organic phase was retained. The aqueous phase was then extracted with ethyl acetate. The combined organic phases were dried over anhydrous magnesium sulfate, and the solvent was removed using a rotary evaporator. The solution was evaporated to dryness, and column chromatography was performed using a mixture of petroleum ether and ethyl acetate as the eluent. The solution was evaporated to dryness to obtain 12.51 g of intermediate 1. The mass spectrometry (MS+1) of intermediate 1 was 369.

[0040] ;

[0041] CAS number for raw material 3: 1641-17-4;

[0042] 12.51 g of intermediate 1, 9.87 g of raw material 3, and 150 ml of tetrahydrofuran were added sequentially to a dry reactor. After stirring until uniformly dispersed, 0.1 g of concentrated sulfuric acid was slowly added dropwise. The temperature was raised to 80 °C, and the reaction was stirred for 6 h. After the reaction was complete, the pH of the system was adjusted to neutral with a 0.1 mol / L sodium bicarbonate aqueous solution. 100 ml of water was added, and the mixture was stirred, shaken, allowed to stand, and separated. The organic phase was retained, evaporated to dryness, and subjected to silica gel column chromatography (using a mixed solution of petroleum ether and ethyl acetate as the eluent). The solution was evaporated to dryness again to obtain 13.66 g of antioxidant stabilizer 1. The mass spectrometry (MS+1) of antioxidant stabilizer 1 was 593, and the NMR of antioxidant stabilizer 1 was as follows: Figure 1 As shown.

[0043] Preparation Examples 2-5

[0044] In Preparation Examples 2-5, antioxidant stabilizer 2-antioxidant 5 were prepared sequentially, following the preparation method of Preparation Example 1, except that raw material 3 was replaced, while the rest remained the same as in Preparation Example 1. For details, please refer to Table 1.

[0045] Table 1.

[0046]

[0047] Example 1

[0048] Preparation of a high-toughness polyester fiber:

[0049] 1. Raw material ratio:

[0050] Polyethylene terephthalate (PET) chips: 75 parts, intrinsic viscosity 0.65 dL / g, end carboxyl group content 20 mol / t, purchased from: Kanghui New Materials Technology Co., Ltd.

[0051] Toughening agent: 8 parts, which is polycaprolactone with a number average molecular weight of 10,000 g / mol, purchased from Suzhou Qihang Biotechnology Co., Ltd.

[0052] Reinforcing filler: 4 parts, nano-calcium carbonate, particle size 50nm, purchased from: Shanghai E. En Chemical Technology Co., Ltd.;

[0053] Antioxidant stabilizer: 2 parts, which is antioxidant stabilizer 1 prepared in Preparation Example 1;

[0054] Lubricant: 1.5 parts, calcium stearate, purchased from Tianjin Xiens Biochemical Technology Co., Ltd.

[0055] 2. Preparation method:

[0056] 1) 75 portions of polyethylene terephthalate (PET) chips were vacuum dried at 90°C for 5 hours until the moisture content dropped to below 0.005%;

[0057] 2) Add the dried polyethylene terephthalate chips, 8 parts toughening agent, 4 parts reinforcing filler, 2 parts antioxidant stabilizer, and 1.5 parts lubricant into a high-speed mixer and mix at 1000 r / min at 90℃ for 18 minutes to obtain the mixture.

[0058] 3) Feed the mixture into a twin-screw extruder, set the screw speed to 250 r / min, and control the temperature of each section as follows: feeding section 210℃, compression section 250℃, melting section 270℃, and die head section 260℃. Melt and extrude at 270℃, and cut into polyester masterbatch by a pelletizer.

[0059] 4) The polyester masterbatch is fed into a spinning machine with a spinneret orifice diameter of 0.3 mm and 54 orifices. Melt spinning is performed at 280℃ and a spinning speed of 1000 m / min. The spun nascent fibers are preheated at 90℃, followed by two-stage stretching: the first stage stretching ratio is 1.8 times and the stretching temperature is 85℃; the second stage stretching ratio is 1.5 times and the stretching temperature is 130℃. Finally, it is set at 160℃ for 8 seconds to obtain a high-toughness polyester.

[0060] Examples 2-5

[0061] The preparation of a high-toughness polyester is carried out by referring to the preparation method of Example 1, except that the antioxidant stabilizers are replaced sequentially with antioxidant stabilizers 2-5, and the rest is the same as in Example 1.

[0062] Comparative Example 1

[0063] The preparation of a high-toughness polyester is carried out by referring to the preparation method of Example 1, except that the antioxidant stabilizer is replaced with antioxidant 1010, and the rest is the same as in Example 1.

[0064] Comparative Example 2

[0065] The preparation of a high-toughness polyester is carried out by referring to the preparation method of Example 1, except that the antioxidant stabilizer is replaced with antioxidant 168, and the rest is the same as in Example 1.

[0066] Comparative Example 3

[0067] The preparation of a high-toughness polyester is carried out by referring to the preparation method of Example 1, except that the antioxidant stabilizer is replaced with ultraviolet absorber UV-9, and the rest is the same as in Example 1.

[0068] Comparative Example 4

[0069] The preparation of a high-toughness polyester is carried out according to the preparation method of Example 1, except that the antioxidant stabilizer is not added, and the rest is the same as in Example 1.

[0070] Comparative Example 5

[0071] The preparation of a high-toughness polyester is carried out according to the preparation method of Example 1, without the addition of the toughening agent, and otherwise remains the same as in Example 1.

[0072] Comparative Example 6

[0073] The preparation of a high-toughness polyester is carried out according to the preparation method of Example 1, without the addition of reinforcing fillers, and otherwise remains the same as in Example 1.

[0074] Performance testing

[0075] 1. Breaking strength and elongation at break: Referring to the test method of GB / T 14344-2022 "Test Method for Tensile Properties of Chemical Fiber Filaments", a high-toughness polyester prepared in the test examples and comparative examples was cut into specimens with a length of 200 mm, and 10 specimens were tested in each group; the breaking strength (unit: cN / dtex) and elongation at break (unit: %) of 10 tests were recorded, and the average value was calculated. The results are shown in Table 2.

[0076] 2. Anti-aging performance test: The high-toughness polyester prepared in the examples and comparative examples was placed in a xenon lamp aging test chamber and exposed for 3600 hours; the breaking strength and elongation at break after aging were tested, and the breaking strength retention rate was calculated.

[0077] Fracture strength retention rate (%) = (fracture strength after aging / fracture strength before aging) × 100%, the results are shown in Table 2.

[0078] Exposure conditions: Radiation intensity: 0.35 W / m 2 (At 340nm wavelength); Temperature cycling: 60℃ (light stage) to 40℃ (dark stage), 8 hours of light + 4 hours of condensation (simulated rain) per cycle; Relative humidity: 50% (light stage), 90% (condensation stage).

[0079] Table 2.

[0080]

[0081] Table 2 shows that the performance indicators of the example group are all superior to those of the comparative group, demonstrating a significant improvement in the material's toughness and aging resistance. Specifically, the example group generally exhibits higher breaking strength and elongation at break, indicating better tensile strength and ductility under external forces. Simultaneously, the breaking strength retention rate is also high, indicating that the material retains good mechanical properties after aging tests. In contrast, the comparative group, due to the lack of key components or the use of different additives, shows significantly inferior performance, especially in breaking strength and elongation at break, where the decline is quite significant. This further verifies that the synergistic effect of the components in the formulation is crucial for improving the overall performance of polyester, and the optimized formulation can effectively enhance the material's toughness and durability.

[0082] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high tenacity polyester, characterized in that, It is prepared from the following components by mass fraction: polyethylene terephthalate chip 70-80 parts, toughening agent 5-15 parts, reinforcing filler 1-5 parts, antioxidant stabilizer 1-3 parts, lubricant 1-2 parts; The antioxidant stabilizer is a compound shown in formula 1: Formula 1: ; R1 in formula 1 is selected from any one of methyl, methoxy, tert-butyl, phenyl, amino.

2. The high tenacity polyester yarn as claimed in claim 1, wherein the high tenacity polyester yarn has a tenacity of 5.5 to 7.5 g / denier. The polyethylene terephthalate chip has a characteristic viscosity of 0.6-0.8 dL / g and a carboxyl end group content ≤30 mol / t.

3. The high tenacity polyester of claim 1, wherein the polyester has a tenacity of at least 20 g / denier. The toughening agent is polycaprolactone with a number average molecular weight of 5000-20000 g / mol.

4. The high tenacity polyester of claim 1, wherein the polyester has a tenacity of at least 20 g / denier. The reinforcing filler is nano calcium carbonate with a particle size of 50-100 nm.

5. The high tenacity polyester of claim 1, wherein the high tenacity polyester has a tenacity of at least 20 g / denier. The lubricant is at least one of calcium stearate or ethylene bis-stearamide.

6. The method for preparing the high tenacity polyester of any one of claims 1-5, characterized in that, It comprises the following steps: 1) vacuum drying the polyethylene terephthalate chip at 80-100℃ for 4-6h until the water content is ≤0.005%; 2) putting the dried polyethylene terephthalate chip, toughening agent, reinforcing filler, antioxidant stabilizer and lubricant into a high-speed mixer, mixing at 900-1100 r / min at 80-100℃ for 15-20 min to obtain a mixture; 3) feeding the mixture into a double-screw extruder, melting and extruding at 260-280℃, and cutting into polyester master batch by a granulator; 4) feeding the polyester master batch into a spinning machine, melting and spinning at 270-290℃, the spinning speed being 800-1200 m / min, preheating the spun nascent fiber at 80-100℃, then stretching at 80-140℃ for 2-4 times, and finally setting at 150-170℃ for 5-10 s to obtain a high-toughness polyester.

7. The method for preparing high-toughness polyester according to claim 6, characterized in that, In step 3), the screw rotation speed of the double-screw extruder is 200-300 r / min, and the temperature of each section is in turn: 200-220℃ for feeding section, 240-260℃ for compression section, 260-280℃ for melting section, and 250-270℃ for head section.

8. The method for preparing high-toughness polyester according to claim 6, characterized in that, In step 4), the spinneret hole diameter of the spinning machine is 0.2-0.4 mm, and the number of holes is 36-72.

9. The method for preparing high-toughness polyester according to claim 6, characterized in that, In step 4), the stretching process adopts two-stage stretching, the first-stage stretching multiple being 1.5-2 times at 80-90℃, and the second-stage stretching multiple being 1-2 times at 120-140℃.

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