Naphthyl polyphenylene sulfide and preparation method and application thereof

Abstract

This invention belongs to the field of polymer materials and relates to a naphthyl polyphenylene sulfide, its preparation method, and its applications. It is a polyphenylene sulfide containing at least one unit of Formula I; wherein X is a naphthalene ring group, and the ratio of naphthalene ring groups to benzene ring groups is not higher than 1.5:7, with a weight-average molecular weight of 42,000~48,000 Da. The naphthyl polyphenylene sulfide provided by this invention not only has higher heat resistance and rigidity but also lower crystallinity, improving its processing performance and showing broad application prospects.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials and relates to a naphthyl polyphenylene sulfide, its preparation method and application. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Polyphenylene sulfide (PPS, chemical formula C6H5S) n It is a high-performance engineering plastic with excellent heat resistance, chemical resistance, mechanical properties and electrical properties, thus demonstrating its unique application value in many industrial fields such as automotive, aerospace, electronics, chemical and environmental protection.

[0004] With technological advancements and the continuous development of new applications, the market demand and application areas of PPS continue to expand, especially in the PPS sheet market. However, research has found that PPS sheets require higher comprehensive performance from PPS, including processing performance, heat resistance, and low crystallinity. While PPS itself, as a linear polymer, has good processing performance, cross-linking PPS significantly reduces its processing performance, making it impossible to simultaneously meet the requirements for comprehensive performance such as processing performance, heat resistance, and low crystallinity. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a naphthyl polyphenylene sulfide, its preparation method, and its applications. The naphthyl polyphenylene sulfide provided by the present invention not only has higher heat resistance and rigidity but also lower crystallinity, thus improving its processing performance and having broad application prospects.

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

[0007] In a first aspect, there is a naphthyl polyphenylene sulfide, which is a polyphenylene sulfide containing at least one unit of Formula I.

[0008]

[0009] Wherein, X is a naphthalene ring group, and the ratio of the number of naphthalene ring groups to benzene ring groups is not higher than 1.5:7, and the weight average molecular weight is 42000~48000 Da. This indicates the location where the functional group is attached.

[0010] In embodiments of the present invention, the four substitution sites of the naphthalene ring group can be located at any four sites on the naphthalene ring, for example:

[0011] , , , , , ,

[0012] etc.

[0013] This invention introduces a naphthalene ring structure into the polyphenylene sulfide (PPS) structure, which improves the heat resistance and rigidity of the polymer. At the same time, this invention controls the ratio of naphthalene ring groups to benzene ring groups to be no higher than 1.5:7, which allows branching to occur in the molecular chain, reducing its crystallinity. This improves the heat resistance of PPS while reducing its crystallinity, and also enhances the processing and application performance of PPS products.

[0014] Secondly, a method for preparing the above-mentioned naphthyl polyphenylene sulfide includes the following steps:

[0015] The dihalobenzene, tetrahalonaphthalene, sodium sulfide and catalyst are dissolved and polymerized under an inert atmosphere and pressure above atmospheric pressure; wherein the molar ratio of dihalobenzene to tetrahalonaphthalene is (7:1.5) to (9.9:0.05).

[0016] The p-dihalobenzene mentioned in this invention can be p-dichlorobenzene, p-dibromobenzene, p-diiodobenzene, etc.

[0017] The tetrahalonaphthalene described in this invention can be tetrachloronaphthalene, tetrabromonaphthalene, tetraiodonaphthalene, etc.

[0018] The inert atmosphere described in this invention refers to a gaseous atmosphere formed by nitrogen, helium, argon, xenon, etc.

[0019] This invention adds a small amount of tetrahalonaphthalene during the preparation of polyphenylene sulfide. By controlling the amount of tetrahalonaphthalene added, the polymer backbone is branched, avoiding cross-linking. At the same time, naphthalene ring groups are introduced into the polyphenylene sulfide, and tetrahalonaphthalene is added in the initial stage to improve the uniformity of the distribution of naphthalene ring groups within the polyphenylene sulfide chain segments. This improves the heat resistance of polyphenylene sulfide while reducing its crystallinity and enhancing the processing and application performance of the polyphenylene sulfide product.

[0020] Thirdly, the application of the above-mentioned naphthyl polyphenylene sulfide in sheet materials.

[0021] The beneficial effects of this invention are as follows:

[0022] This invention introduces naphthyl groups into polyphenylene sulfide (PPS), improving its heat resistance and rigidity. Simultaneously, by controlling the amount of naphthyl ring groups introduced, branching of the molecular weight is controlled, and large-scale cross-linking is avoided, reducing its crystallinity, enhancing its mechanical properties, and improving its processability. Experiments show that, compared with conventional linear PPS, the naphthyl PPS provided by this invention can increase tensile strength by 3-18%, flexural strength by 3-16%, reduce crystallization temperature by 3-19%, and increase heat deformation temperature by 2-9%. Attached Figure Description

[0023] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0024] Figure 1 The infrared spectrum of naphthyl polyphenylene sulfide prepared in Example 1 of this invention. Detailed Implementation

[0025] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0026] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0027] In view of the fact that further improving the heat resistance of PPS cannot be achieved while maintaining its processing performance, this invention proposes a naphthyl polyphenylene sulfide, its preparation method and application.

[0028] In one typical embodiment of the present invention, a naphthyl polyphenylene sulfide is provided, which is a polyphenylene sulfide containing at least one unit of Formula I;

[0029]

[0030] Wherein, X is a naphthalene ring group, and the ratio of the number of naphthalene ring groups to benzene ring groups is not higher than 1.5:7, and the weight average molecular weight is 42000~48000 Da.

[0031] The naphthalene ring group described in this invention can be , , , , , And so on. In some embodiments, X is... .

[0032] In some embodiments, the ratio of naphthalene ring groups to benzene ring groups is (0.05:9.9) to (1.5:7), preferably (0.5:9) to (1:8). When the ratio of naphthalene ring groups to benzene ring groups is (0.5:9) to (1:8) and the weight-average molecular weight is 43,500 to 48,000 Da, the performance of naphthyl polyphenylene sulfide is better.

[0033] In some embodiments, the crystallization temperature is 179~213 °C.

[0034] In some embodiments, the heat distortion temperature is 265~283 ℃.

[0035] In some embodiments, the flexural modulus is 2615~2928 MPa.

[0036] Another embodiment of the present invention provides a method for preparing the above-mentioned naphthyl polyphenylene sulfide, comprising the following steps:

[0037] The dihalobenzene, tetrahalonaphthalene, sodium sulfide and catalyst are dissolved and polymerized under an inert atmosphere and pressure above atmospheric pressure; wherein the molar ratio of dihalobenzene to tetrahalonaphthalene is (7:1.5) to (9.9:0.05).

[0038] In some embodiments, the polymerization reaction pressure is 0.25–0.95 MPa, and the polymerization temperature is 200–260 °C. Studies have shown that the polymerization process affects the molecular weight of naphthyl polyphenylene sulfide (NPS), and the molecular weight also affects the processing performance of NPS. Specifically, the polymerization reaction is divided into three stages: in the first stage, the pressure is 0.25–0.40 MPa and the temperature is 200–220 °C; in the second stage, the pressure is 0.50–0.65 MPa and the temperature is 230–250 °C; and in the third stage, the pressure is 0.65–0.95 MPa and the temperature is 250–260 °C. By controlling the polymerization process, the molecular weight of NPS can be better controlled, thereby further improving its processing performance. Specifically, the first stage lasts 1.5–2.5 h; the second stage lasts 1.5–2.5 h; and the third stage lasts 2.5–3.5 h.

[0039] In some embodiments, the molar ratio of p-dihalobenzene to tetrahalonaphthalene is (8:1) to (9:0.5).

[0040] In some embodiments, the total molar amount of halogen elements in dihalobenzene and tetrahalonaphthalene is in the molar ratio of sodium sulfide to sodium sulfide of 2 to 2.02:1.

[0041] In some embodiments, the catalyst is sodium hexanoate.

[0042] To dissolve p-dihalobenzene, tetrahalonaphthalene, sodium sulfide, and the catalyst, the present invention employs a polar solvent for dissolution. In some embodiments, the solvent for dissolving p-dihalobenzene, tetrahalonaphthalene, sodium sulfide, and the catalyst is N-methylpyrrolidone (NMP).

[0043] The sodium sulfide used in this invention can be anhydrous sodium sulfide or sodium sulfide pentahydrate. When sodium sulfide pentahydrate is used, its water of crystallization needs to be removed before use in the polymerization reaction. In some embodiments, when sodium sulfide pentahydrate is used, the method for removing the water of crystallization is as follows: under an inert atmosphere and in a closed system, sodium sulfide pentahydrate is added to a non-aqueous solvent and heated to a temperature not lower than the boiling point of the non-aqueous solvent to remove the water of crystallization. This invention removes the water of crystallization under an inert atmosphere to prevent oxidation of the sodium sulfide at high temperatures; the selection of a non-aqueous solvent and the heating to a temperature not lower than the boiling point of the non-aqueous solvent under closed conditions allow the non-aqueous solvent to evaporate, thus placing the system at a pressure higher than atmospheric pressure, thereby enabling better removal of the water of crystallization from the sodium sulfide pentahydrate. Specifically, the non-aqueous solvent is N-methylpyrrolidone. Specifically, the temperature for water of crystallization removal is 210~230 °C. Specifically, the time for water of crystallization removal is 2~3 h.

[0044] In some embodiments, the purification process after polymerization is as follows: cooling, adding water and stirring to form a slurry, centrifuging and filtering, washing and drying.

[0045] A third embodiment of the present invention provides an application of the above-mentioned naphthyl polyphenylene sulfide in a sheet material.

[0046] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments and comparative examples.

[0047] The tetrachloronaphthalene used in the following examples is 1,3,5,7-tetrachloronaphthalene.

[0048] Example 1

[0049] A method for preparing naphthyl polyphenylene sulfide, wherein the overall molar ratio of reactants is sodium sulfide pentahydrate: p-dichlorobenzene: 1,3,5,7-tetrachloronaphthalene: NMP: sodium hexanoate = 1:0.95:0.025:4:0.4; the molar ratio of reactants in the dehydration stage is sodium sulfide pentahydrate: NMP = 1:2; and the molar ratio of reactants in the polymerization stage is p-dichlorobenzene: tetrachloronaphthalene: NMP: sodium hexanoate = 0.95:0.05:2:0.4. The steps are as follows:

[0050] (1) Under a nitrogen atmosphere, NMP and sodium sulfide pentahydrate are added to a high-pressure reactor, the temperature is raised to 220°C, and the mixture is stirred continuously for 2-3 hours to remove the water of crystallization from the sodium sulfide at high temperature. The water content in the dehydrated fraction is calculated. When the amount of water removed reaches 90% of the theoretical amount of water removed, the dehydration is completed. Then the system is cooled down and NMP removed during the dehydration stage is added.

[0051] (2) Add p-dichlorobenzene, tetrachloronaphthalene, sodium hexanoate and NMP to the high-pressure reactor of sodium sulfide solution after dehydration in step (1), perform nitrogen purging twice, and then heat and pressurize to carry out polymerization reaction; the polymerization reaction process is as follows: the first stage is 215℃ and 0.35MPa for 2 h, the second stage is 245℃ and 0.65MPa for 2 h, and the third stage is 260℃ and 0.95MPa for 3 h; the polymerization reaction yields a slurry containing naphthyl polyphenylene sulfide.

[0052] (3) The slurry obtained in step (2) is rapidly cooled to 75°C, water is added and stirred to form a pulp, with a ratio of deionized water to NMP of 4:4. Finally, the material is centrifuged, filtered, washed and dried to obtain the naphthyl polyphenylene sulfide product.

[0053] The infrared spectrum of the naphthyl polyphenylene sulfide product obtained in this embodiment is as follows: Figure 1 As shown, Figure 1 3000cm can be seen in it -1 The nearby vibrational peaks can be attributed to the symmetric and antisymmetric stretching vibrations of CH on the aromatic ring; 2000-1660 cm⁻¹ -1 The peaks at 1580 cm⁻¹ are the overtone and combination frequency absorption peaks of naphthalene. -1 It is a C=C symmetrical stretching vibration; 1470cm -1 The absorption peak at 1100 cm⁻¹ is the absorption peak of the aromatic ring skeleton vibration; -1 The peak at 790 cm⁻¹ represents the CS stretching vibration peak on the aromatic ring. -1 The vibrational peak at that point is the out-of-plane bending vibration of isolated CH groups in the naphthalene molecule, which can be attributed to the introduction of tetrachloronaphthalene. The above infrared results indicate that the synthesized sample is a polyphenylene sulfide molecule containing naphthyl groups.

[0054] Example 2

[0055] A method for preparing naphthyl polyphenylene sulfide, wherein the overall molar ratio of reactants is sodium sulfide pentahydrate: p-dichlorobenzene: 1,3,5,7-tetrachloronaphthalene: NMP: sodium hexanoate = 1:0.90:0.05:4:0.4; the molar ratio of reactants in the dehydration stage is sodium sulfide pentahydrate: NMP = 1:2; and the molar ratio of reactants in the polymerization stage is p-dichlorobenzene: tetrachloronaphthalene: NMP: sodium hexanoate = 0.90:0.10:2:0.4. The steps are as follows:

[0056] (1) Under a nitrogen atmosphere, NMP and sodium sulfide pentahydrate are added to a high-pressure reactor, the temperature is raised to 210°C, and the mixture is stirred continuously for 2-3 hours to remove the water of crystallization from the sodium sulfide at high temperature. The water content in the dehydrated fraction is calculated. When the amount of water removed reaches 90% of the theoretical amount of water removed, the dehydration is completed. Then the system is cooled down and NMP removed during the dehydration stage is added.

[0057] (2) Add dichlorobenzene, tetrachloronaphthalene, sodium hexanoate and NMP to the high-pressure reactor of sodium sulfide solution after dehydration in step (1), perform nitrogen purging 3 times, and then heat and pressurize to carry out polymerization reaction; the polymerization reaction process is as follows: the first stage is 210℃ and 0.32MPa for 2 h, the second stage is 240℃ and 0.60MPa for 2 h, and the third stage is 260℃ and 0.90MPa for 3 h; the polymerization reaction yields a slurry containing naphthyl polyphenylene sulfide.

[0058] (3) The slurry obtained in step (2) is rapidly cooled to 80°C, water is added and stirred to form a pulp, with a ratio of deionized water to NMP of 4:4. Finally, the material is centrifuged, filtered, washed and dried to obtain the naphthyl polyphenylene sulfide product.

[0059] Example 3

[0060] A method for preparing naphthyl polyphenylene sulfide, wherein the overall molar ratio of reactants is sodium sulfide pentahydrate: p-dichlorobenzene: 1,3,5,7-tetrachloronaphthalene: NMP: sodium hexanoate = 1:0.85:0.075:4:0.4; the molar ratio of reactants in the dehydration stage is sodium sulfide pentahydrate: NMP = 1:2; and the molar ratio of reactants in the polymerization stage is p-dichlorobenzene: tetrachloronaphthalene: NMP: sodium hexanoate = 0.85:0.15:2:0.4. The steps are as follows:

[0061] (1) Under a nitrogen atmosphere, NMP and sodium sulfide pentahydrate are added to a high-pressure reactor, the temperature is raised to 230°C, and the mixture is stirred continuously for 2-3 hours to remove the water of crystallization from the sodium sulfide at high temperature. The water content in the dehydrated fraction is calculated. When the amount of water removed reaches 90% of the theoretical amount of water removed, the dehydration is completed. Then the system is cooled down and NMP removed during the dehydration stage is added.

[0062] (2) Add p-dichlorobenzene, tetrachloronaphthalene, sodium hexanoate and NMP to the high-pressure reactor of sodium sulfide solution after dehydration in step (1), perform nitrogen purging twice, and then heat and pressurize to carry out polymerization reaction; the polymerization reaction process is as follows: the first stage is 210℃ and 0.30MPa for 2 h, the second stage is 235℃ and 0.58MPa for 2 h, and the third stage is 260℃ and 0.90MPa for 3 h; the polymerization reaction yields a slurry containing naphthyl polyphenylene sulfide.

[0063] (3) The slurry obtained in step (2) is rapidly cooled to 75°C, water is added and stirred to form a pulp, with a ratio of deionized water to NMP of 4:4. Finally, the material is centrifuged, filtered, washed and dried to obtain the naphthyl polyphenylene sulfide product.

[0064] Example 4

[0065] A method for preparing naphthyl polyphenylene sulfide, wherein the overall molar ratio of reactants is sodium sulfide pentahydrate: p-dichlorobenzene: tetrachloronaphthalene: NMP: sodium hexanoate = 1:0.80:0.10:4:0.4; the molar ratio of reactants in the dehydration stage is sodium sulfide pentahydrate: NMP = 1:2; and the molar ratio of reactants in the polymerization stage is p-dichlorobenzene: tetrachloronaphthalene: NMP: sodium hexanoate = 0.80:0.20:2:0.4. The steps are as follows:

[0066] (1) Under a nitrogen atmosphere, NMP and sodium sulfide pentahydrate are added to a high-pressure reactor, the temperature is raised to 220°C, and the mixture is stirred continuously for 2-3 hours to remove the water of crystallization from the sodium sulfide at high temperature. The water content in the dehydrated fraction is calculated. When the amount of water removed reaches 90% of the theoretical amount of water removed, the dehydration is completed. Then the system is cooled down and NMP removed during the dehydration stage is added.

[0067] (2) Add p-dichlorobenzene, tetrachloronaphthalene, sodium hexanoate and NMP to the high-pressure reactor of sodium sulfide solution after dehydration in step (1), perform nitrogen purging 3 times, and then heat and pressurize to carry out polymerization reaction; the polymerization reaction process is as follows: the first stage is 205℃ and 0.29MPa for 2 h, the second stage is 235℃ and 0.58MPa for 2 h, and the third stage is 260℃ and 0.90MPa for 3 h; the polymerization reaction yields a slurry containing naphthyl polyphenylene sulfide.

[0068] (3) The slurry obtained in step (2) is rapidly cooled to 80°C, water is added and stirred to form a pulp, with a ratio of deionized water to NMP of 4:4. Finally, the material is centrifuged, filtered, washed and dried to obtain the naphthyl polyphenylene sulfide product.

[0069] Example 5

[0070] A method for preparing naphthyl polyphenylene sulfide, wherein the overall molar ratio of reactants is sodium sulfide pentahydrate: p-dichlorobenzene: tetrachloronaphthalene: NMP: sodium hexanoate = 1:0.90:0.05:4:0.4; the molar ratio of reactants in the dehydration stage is sodium sulfide pentahydrate: NMP = 1:2; and the molar ratio of reactants in the polymerization stage is p-dichlorobenzene: tetrachloronaphthalene: NMP: sodium hexanoate = 0.95:0.05:2:0.4. The steps are as follows:

[0071] (1) Under a nitrogen atmosphere, NMP and sodium sulfide pentahydrate are added to a high-pressure reactor, the temperature is raised to 220°C, and the mixture is stirred continuously for 2-3 hours to remove the water of crystallization from the sodium sulfide at high temperature. The water content in the dehydrated fraction is calculated. When the amount of water removed reaches 90% of the theoretical amount of water removed, the dehydration is completed. Then the system is cooled down and NMP removed during the dehydration stage is added.

[0072] (2) Add p-dichlorobenzene, tetrachloronaphthalene, sodium hexanoate and NMP to the high-pressure reactor of sodium sulfide solution after dehydration in step (1), perform nitrogen purging twice, and then heat and pressurize to carry out polymerization reaction; the polymerization reaction process is as follows: the first stage is 220℃ and 0.40MPa for 2 h, the second stage is 250℃ and 0.65MPa for 2 h, and the third stage is 260℃ and 0.95MPa for 3 h; the polymerization reaction yields a slurry containing naphthyl polyphenylene sulfide.

[0073] (3) The slurry obtained in step (2) is rapidly cooled to 75°C, water is added and stirred to form a pulp, with a ratio of deionized water to NMP of 4:4. Finally, the material is centrifuged, filtered, washed and dried to obtain the naphthyl polyphenylene sulfide product.

[0074] Example 6

[0075] A method for preparing naphthyl polyphenylene sulfide, wherein the overall molar ratio of reactants is sodium sulfide pentahydrate: p-dichlorobenzene: tetrachloronaphthalene: NMP: sodium hexanoate = 1:0.90:0.05:4:0.4; the molar ratio of reactants in the dehydration stage is sodium sulfide pentahydrate: NMP = 1:2; and the molar ratio of reactants in the polymerization stage is p-dichlorobenzene: tetrachloronaphthalene: NMP: sodium hexanoate = 0.95:0.05:2:0.4. The steps are as follows:

[0076] (1) Under a nitrogen atmosphere, NMP and sodium sulfide pentahydrate are added to a high-pressure reactor, the temperature is raised to 220°C, and the mixture is stirred continuously for 2-3 hours to remove the water of crystallization from the sodium sulfide at high temperature. The water content in the dehydrated fraction is calculated. When the amount of water removed reaches 90% of the theoretical amount of water removed, the dehydration is completed. Then the system is cooled down and NMP removed during the dehydration stage is added.

[0077] (2) Add dichlorobenzene, tetrachloronaphthalene, sodium hexanoate and NMP to the high-pressure reactor of sodium sulfide solution after dehydration in step (1), perform nitrogen purging twice, and then heat and pressurize to carry out polymerization reaction; the polymerization reaction process is as follows: the first stage is 200℃ and 0.25MPa for 2 h, the second stage is 230℃ and 0.50MPa for 2 h, and the third stage is 250℃ and 0.65MPa for 3 h; the polymerization reaction yields a slurry containing naphthyl polyphenylene sulfide.

[0078] (3) The slurry obtained in step (2) is rapidly cooled to 75°C, water is added and stirred to form a pulp, with a ratio of deionized water to NMP of 4:4. Finally, the material is centrifuged, filtered, washed and dried to obtain the naphthyl polyphenylene sulfide product.

[0079] Comparative Example 1

[0080] A method for preparing naphthyl polyphenylene sulfide, wherein the overall molar ratio of reactants is sodium sulfide pentahydrate: p-dichlorobenzene: NMP: sodium hexanoate = 1:1:4:0.4; the molar ratio of reactants in the dehydration stage is sodium sulfide pentahydrate: NMP = 1:2; and the molar ratio of reactants in the polymerization stage is p-dichlorobenzene: NMP: sodium hexanoate = 1:2:0.4. The steps are as follows:

[0081] (1) Under a nitrogen atmosphere, NMP and sodium sulfide pentahydrate are added to a high-pressure reactor, the temperature is raised to 220°C, and the mixture is stirred continuously for 2-3 hours to remove the water of crystallization from the sodium sulfide at high temperature. The water content in the dehydrated fraction is calculated. When the amount of water removed reaches 90% of the theoretical amount of water removed, the dehydration is completed. Then the system is cooled down and NMP removed during the dehydration stage is added.

[0082] (2) Add dichlorobenzene, sodium hexanoate and NMP to the high-pressure reactor of sodium sulfide solution after dehydration in step (1), perform nitrogen purging twice, and then heat and pressurize to carry out polymerization reaction; the polymerization reaction process is as follows: the first stage is 215℃ and 0.35MPa for 2 h, the second stage is 245℃ and 0.65MPa for 2 h, and the third stage is 260℃ and 0.95MPa for 3 h; the polymerization reaction yields a slurry containing naphthyl polyphenylene sulfide.

[0083] (3) The slurry obtained in step (2) is rapidly cooled to 75°C, water is added and stirred to form a pulp, with a ratio of deionized water to NMP of 4:4. Finally, the material is centrifuged, filtered, washed and dried to obtain the polyphenylene sulfide product.

[0084] Comparative Example 2

[0085] A method for preparing naphthyl polyphenylene sulfide, wherein the overall molar ratio of reactants is sodium sulfide pentahydrate: p-dichlorobenzene: dichloronaphthalene: NMP: sodium hexanoate = 1:0.95:0.05:4:0.4; the molar ratio of reactants in the dehydration stage is sodium sulfide pentahydrate: NMP = 1:2; and the molar ratio of reactants in the polymerization stage is p-dichlorobenzene: dichloronaphthalene: NMP: sodium hexanoate = 0.95:0.05:2:0.4. The steps are as follows:

[0086] (1) Under a nitrogen atmosphere, NMP and sodium sulfide pentahydrate are added to a high-pressure reactor, the temperature is raised to 220°C, and the mixture is stirred continuously for 2-3 hours to remove the water of crystallization from the sodium sulfide at high temperature. The water content in the dehydrated fraction is calculated. When the amount of water removed reaches 90% of the theoretical amount of water removed, the dehydration is completed. Then the system is cooled down and NMP removed during the dehydration stage is added.

[0087] (2) Add p-dichlorobenzene, dichloronaphthalene, sodium hexanoate and NMP to the high-pressure reactor of sodium sulfide solution after dehydration in step (1), perform nitrogen purging twice, and then heat and pressurize to carry out polymerization reaction; the polymerization reaction process is as follows: the first stage is 215℃ and 0.35MPa for 2 h, the second stage is 245℃ and 0.65MPa for 2 h, and the third stage is 260℃ and 0.95MPa for 3 h; the polymerization reaction yields a slurry containing naphthyl polyphenylene sulfide.

[0088] (3) The slurry obtained in step (2) is rapidly cooled to 75°C, water is added and stirred to form a pulp, with a ratio of deionized water to NMP of 4:4. Finally, the material is centrifuged, filtered, washed and dried to obtain the naphthyl polyphenylene sulfide product.

[0089] The performance of the products prepared in each embodiment and comparative example is shown in Table 1.

[0090] Table 1 shows the performance of Examples 1-6 and Comparative Examples 1-2.

[0091]

[0092] Tensile strength was tested according to GB / T1040.2-2022 "Determination of Tensile Properties of Plastics" Part 2: Test Conditions for Molded and Extruded Plastics. Flexural strength and flexural modulus were tested according to GB / T 9341-2008 "Determination of Flexural Properties of Plastics". Crystallization temperature was obtained by DSC (10℃ / min). The heat distortion temperature test method was as follows: the prepared resin was blended with 40% GF through a screw press and then tested under the same conditions. The test referenced ISO72 standard, with a high load of 1.80 MPa and a heating rate of 120℃ / hr.

[0093] Table 1 shows that, compared with Comparative Example 1, Examples 1-6 exhibit improved tensile strength, flexural strength, flexural modulus, and heat distortion temperature, while reducing crystallinity. Compared with Comparative Example 2, Examples 1-6 not only possess higher tensile and flexural strength but also lower crystallinity. Among them, Examples 2-4 and 6 show higher flexural modulus and heat distortion temperature. Therefore, based on Examples 1-6, the present invention demonstrates greater potential in product development and processing applications, and has broad prospects.

[0094] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A naphthyl polyphenylene sulfide, characterized in that it is... Polyphenylene sulfide containing at least one unit of Formula I; Wherein, X is a naphthalene ring group, and the ratio of naphthalene ring groups to benzene ring groups is (0.5:9) to (1:8), with a weight-average molecular weight of 43700 to 48000 Da; the naphthalene ring group is... ; The crystallization temperature is 179~197 ℃; The heat distortion temperature is 271-283 ℃; The flexural modulus is 2790-2928 MPa.

2. A method for preparing the naphthyl polyphenylene sulfide according to claim 1, characterized in that, Includes the following steps: The dihalobenzene, tetrahalonaphthalene, sodium sulfide and catalyst are dissolved and polymerized under an inert atmosphere and pressure higher than atmospheric pressure; wherein the molar ratio of dihalobenzene to tetrahalonaphthalene is (8:1) to (9:0.5). The catalyst is sodium hexanoate; the tetrahalonaphthalene is 1,3,5,7-tetrachloronaphthalene; the solvent for dissolving p-dihalobenzene, tetrahalonaphthalene, sodium sulfide and the catalyst is N-methylpyrrolidone; The total molar ratio of halogen elements to sodium sulfide in dihalobenzene and tetrahalonaphthalene is 2~2.02:

1.

3. The preparation method according to claim 2, characterized in that, The polymerization reaction occurs at a pressure of 0.25~0.95 MPa and a temperature of 200~260 ℃.

4. The preparation method according to claim 2, characterized in that, The polymerization reaction is divided into three stages. In the first stage, the pressure is 0.25~0.40 MPa and the temperature is 200~220 ℃. In the second stage, the pressure is 0.50~0.65 MPa and the temperature is 230~250 ℃. In the third stage, the pressure is 0.65~0.95 MPa and the temperature is 250~260 ℃.

5. The application of the naphthyl polyphenylene sulfide according to claim 1 in a sheet material.

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