Naphthyl polyphenylene sulfide as well as preparation method and application thereof

Abstract

The invention belongs to the field of high polymer materials, and relates to naphthyl polyphenylene sulfide as well as a preparation method and application thereof. The modified polyphenylene sulfide is polyphenylene sulfide at least containing a unit shown in a formula I; x is a naphthalene ring group, the number ratio of the naphthalene ring group to the benzene ring group is not higher than 1.5: 7, and the weight-average molecular weight is 42000-48000 Da. The naphthyl polyphenylene sulfide provided by the invention not only has higher heat resistance and rigidity, but also has lower crystallinity, the processability of the naphthyl polyphenylene sulfide is improved, and the naphthyl polyphenylene sulfide has wide application prospects.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of high polymer materials, and relates to a naphthyl polyphenylene sulfide as well as a preparation method and application thereof. BACKGROUND

[0002] The information disclosed in this Background section is for the purpose of providing context only, and is not necessarily recognized as prior art by the Patent Office.

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

[0004] With the progress of technology and the continuous development of new applications, the market demand and application field of PPS are still expanding, especially in the field of PPS plate market. However, research shows that PPS plate has higher requirements for the comprehensive performance of PPS such as processing performance, heat resistance and low crystallinity; and PPS itself is a linear polymer with good processing performance, and if PPS is crosslinked, its processing performance will be greatly reduced, thus it cannot meet the requirements of comprehensive performance such as processing performance, heat resistance and low crystallinity. SUMMARY

[0005] In order to solve the problems of the prior art, the present application aims to provide a naphthyl polyphenylene sulfide as well as a preparation method and application thereof. The naphthyl polyphenylene sulfide provided by the present application not only has higher heat resistance and rigidity, but also has lower crystallinity, thus improving its processing performance and having a broad application prospect.

[0006] In order to achieve the above-mentioned purpose, the technical scheme of the present application is as follows: In a first aspect, a naphthyl polyphenylene sulfide is provided, which is a polyphenylene sulfide containing at least one unit represented by formula I:

[0007] wherein X is a naphthalene ring group, and the number ratio of the naphthalene ring group to the benzene ring group is not higher than 1.5:7, and the weight average molecular weight is 42000-48000 Da. Representative group connection position.

[0008] In the embodiment of the present application, the four substitution sites of the naphthalene ring group can be located at any four sites of the naphthalene ring, for example: , 、 、 、 、 , and so on.

[0009] The present application introduces naphthalene ring structure into polyphenylene sulfide structure, improves the heat resistance and rigidity of the polymer, and controls the number ratio of naphthalene ring groups and benzene ring groups to be not higher than 1.5:7, so that branching can be generated in the molecular chain, the crystallinity is reduced, the heat resistance of the polyphenylene sulfide is improved while the crystallinity is reduced, and the processing and application performance of the polyphenylene sulfide product is improved.

[0010] In a second aspect, a preparation method of the naphthalene-based polyphenylene sulfide is provided, and the method comprises the following steps: dissolving p-dihalobenzene, tetrahalonaphthalene, sodium sulfide and a catalyst, and performing polymerization reaction under the condition of inert atmosphere and higher than atmospheric pressure; wherein the molar ratio of p-dihalobenzene to tetrahalonaphthalene is (7:1.5)~(9.9:0.05).

[0011] The p-dihalobenzene can be p-dichlorobenzene, p-dibromobenzene, p-diiodobenzene and the like.

[0012] The tetrahalonaphthalene can be tetrahalonaphthalene, tetrahalonaphthalene, tetrahalonaphthalene and the like.

[0013] The inert atmosphere refers to a gas atmosphere formed by nitrogen, helium, argon, xenon and the like.

[0014] In the preparation process of the polyphenylene sulfide, a small amount of tetrahalonaphthalene is added, the addition amount of the tetrahalonaphthalene is controlled to make the polymer main chain branched, crosslinking is avoided, the naphthalene ring group is introduced into the polyphenylene sulfide, and the tetrahalonaphthalene is added in the initial stage, the distribution uniformity of the naphthalene ring group in the chain segment of the polyphenylene sulfide is improved, so that the heat resistance of the polyphenylene sulfide is improved while the crystallinity is reduced, and the processing and application performance of the polyphenylene sulfide product is improved.

[0015] In a third aspect, the naphthalene-based polyphenylene sulfide is applied to a plate.

[0016] The present application has the following beneficial effects: The present application introduces naphthalene group into polyphenylene sulfide, improves the heat resistance and rigidity of the polyphenylene sulfide, controls the introduction amount of the naphthalene ring group, controls the molecular weight to be branched and avoids large-scale crosslinking, reduces the crystallinity, enhances the mechanical properties, and improves the processing performance. Experiments show that, compared with conventional linear polyphenylene sulfide, the tensile strength of the naphthalene-based polyphenylene sulfide provided by the present application can be improved by 3%~18%, the bending strength can be improved by 3%~16%, the crystallization temperature can be reduced by 3%~19%, and the thermal deformation temperature can be improved by 2%~9%. BRIEF DESCRIPTION OF DRAWINGS

[0017] The accompanying drawings, which form a part of this specification, are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification. The embodiments of the application, and their

[0018] Figure 1 The infrared spectrum of the naphthyl polyphenylene sulfide prepared for Example 1 of the present application. DETAILED DESCRIPTION

[0019] It should be noted that the following detailed description is exemplary in nature and is intended to provide further description of the application. Unless otherwise defined, 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 application belongs.

[0020] It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments in accordance with the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, components, and / or groups thereof, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0021] In view of further improving the heat resistance of PPS, but unable to take into account the processing performance, the present application provides a naphthyl polyphenylene sulfide and a preparation method and application thereof.

[0022] In a typical embodiment of the present application, a naphthyl polyphenylene sulfide is provided, which is a polyphenylene sulfide containing at least one unit shown in Formula I;

[0023] wherein X is a naphthalene ring group, and the number ratio of the naphthalene ring group to the benzene ring group is not higher than 1.5:7, and the weight average molecular weight is 42000-48000 Da.

[0024] The naphthalene ring group in the present application can be , , , , , , etc. In some embodiments, X is .

[0025] In some embodiments, the number ratio of the naphthalene ring group to the benzene ring group is (0.05:9.9)-(1.5:7), preferably (0.5:9)-(1:8). When the number ratio of the naphthalene ring group to the benzene ring group is (0.5:9)-(1:8) and the weight average molecular weight is 43500-48000 Da, the naphthyl polyphenylene sulfide has better performance.

[0026] In some embodiments, the crystallization temperature is 179~213 °C.

[0027] In some embodiments, the heat distortion temperature is 265~283 ℃.

[0028] In some embodiments, the flexural modulus is 2615~2928 MPa.

[0029] Another embodiment of the present invention provides a method for preparing the above-mentioned naphthyl polyphenylene sulfide, comprising the following steps: 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).

[0030] 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.

[0031] In some embodiments, the molar ratio of p-dihalobenzene to tetrahalonaphthalene is (8:1) to (9:0.5).

[0032] In some embodiments, the total molar amount of halogen elements in dihalobenzene and tetrahalonaphthene is in the molar ratio of sodium sulfide to 2~2.02:1.

[0033] In some embodiments, the catalyst is sodium hexanoate.

[0034] 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).

[0035] 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.

[0036] 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.

[0037] A third embodiment of the present invention provides an application of the above-mentioned naphthyl polyphenylene sulfide in a sheet material.

[0038] 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.

[0039] The tetrachloronaphthalene used in the following examples is 1,3,5,7-tetrachloronaphthalene.

[0040] Example 1 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: (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.

[0041] (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.

[0042] (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.

[0043] 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.

[0044] Example 2 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: (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.

[0045] (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.

[0046] (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.

[0047] Example 3 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: (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.

[0048] (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.

[0049] (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.

[0050] Example 4 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: (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 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.

[0052] (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.

[0053] Example 5 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: (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.

[0054] (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.

[0055] (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.

[0056] Example 6 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: (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.

[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 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.

[0058] (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.

[0059] Comparative Example 1 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: (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.

[0060] (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.

[0061] (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.

[0062] Comparative Example 2 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: (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.

[0063] (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.

[0064] (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.

[0065] The performance of the products prepared in each embodiment and comparative example is shown in Table 1.

[0066] Table 1 shows the performance of Examples 1-6 and Comparative Examples 1-2.

[0067] 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.

[0068] 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.

[0069] 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 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.

2. The naphthyl polyphenylene sulfide as described in claim 1, characterized in that, X is .

3. The naphthyl polyphenylene sulfide as described in claim 1, characterized in that, The ratio of naphthalene ring groups to benzene ring groups is (0.5:9) to (1:8).

4. The naphthyl polyphenylene sulfide as described in claim 1, characterized in that, The crystallization temperature is 179~213 ℃; Alternatively, the heat distortion temperature is 265~283 ℃; Alternatively, the flexural modulus is 2615~2928 MPa.

5. 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 above atmospheric pressure; wherein the molar ratio of dihalobenzene to tetrahalonaphthalene is (7:1.5) to (9.9:0.05).

6. The preparation method according to claim 5, characterized in that, The polymerization reaction occurs at a pressure of 0.25~0.95 MPa and a temperature of 200~260 ℃.

7. The preparation method according to claim 5, 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 ℃.

8. The preparation method according to claim 5, characterized in that, The molar ratio of p-dihalobenzene to tetrahalonaphthalene is (8:1) to (9:0.5); Alternatively, the total molar ratio of halogen elements in dihalobenzene and tetrahalonaphthalene to the molar ratio of sodium sulfide is 2~2.02:

1.

9. The preparation method according to claim 5, characterized in that, The catalyst is sodium hexanoate; Alternatively, the solvent for dissolving p-dihalobenzene, tetrahalonaphthalene, sodium sulfide, and the catalyst may be N-methylpyrrolidone.

10. The use of naphthyl polyphenylene sulfide according to any one of claims 1 to 4 in a sheet material.

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