Antistatic polystyrene and preparation method thereof

Abstract

The invention provides antistatic polystyrene and a preparation method thereof. The antistatic polystyrene comprises the following raw materials in parts by mass: 100 parts of polystyrene and 5-15 parts of organic anion quaternary ammonium salt modified polystyrene. Wherein the organic anion quaternary ammonium salt modified polystyrene is obtained by quaternizing a chloromethyl styrene-styrene copolymer and then carrying out anion exchange on the quaternized chloromethyl styrene-styrene copolymer and an organic anion metal salt. By introducing the organic anion quaternary ammonium salt modified polystyrene into a polystyrene matrix, the antistatic performance of the material can be remarkably improved, and the performance is kept stable in the long-term use process, so that the problems of dust adsorption, discharge interference and appearance degradation caused by static accumulation are reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high polymer materials, in particular to an antistatic polystyrene and a preparation method thereof. BACKGROUND

[0002] Polystyrene (PS) is widely used in packaging materials, electronic and electrical housings, optical elements and daily products due to its good transparency, high rigidity and excellent forming and processing performance. However, polystyrene is a typical electrically insulating material, and its surface resistivity is usually above 10 14 Ω, which easily accumulates static electricity during use. These static charges not only cause dust adsorption, affecting the appearance and cleanliness of the product, but also may cause electronic component malfunction or even electrostatic discharge damage, thereby limiting the application of polystyrene in electronics, optics and clean environments.

[0003] To improve the antistatic performance of polystyrene, the related art mainly adds migration type antistatic agents, dopes conductive fillers and chemically modifies, etc. For example, a surfactant, a quaternary ammonium salt small molecule or a polyether compound is added to polystyrene, so that it migrates to the surface of the material to form a conductive layer during processing or use, thereby reducing the surface resistance. This method can obtain certain antistatic effect at the beginning, but the additives are easily imbalanced in surface migration, washed or removed by abrasion, resulting in rapid attenuation of antistatic performance and short service life. By adding conductive fillers such as carbon black, carbon nanotubes and metal particles, a conductive network is formed in the polystyrene matrix. Although this method can significantly reduce the resistance, it often requires a high filling amount, which easily leads to a decrease in transparency, a darkening of color, and an adverse effect on mechanical properties and processing fluidity, thereby limiting the application in transparent products and high appearance requirement scenarios. In addition, there is also a method of introducing a charged group into the polystyrene chain to obtain more stable antistatic performance, but the existing system is prone to ion re-association or migration, so that the antistatic effect still attenuates in long-term use, and it is difficult to maintain stability.

[0004] Therefore, how to realize long-term stable antistatic effect while ensuring the appearance quality of polystyrene material is still a technical problem to be solved in the field. SUMMARY

[0005] The present application provides an antistatic polystyrene and a preparation method thereof. The antistatic polystyrene is modified by introducing a specific structure of organic anion quaternary ammonium salt into the polystyrene matrix, so as to have good and stable antistatic effect while maintaining the appearance quality of the material.

[0006] In a first aspect, the application provides an antistatic polystyrene, comprising 100 parts by mass of polystyrene and 5-15 parts by mass of organic anion quaternary ammonium salt modified polystyrene; wherein the organic anion quaternary ammonium salt modified polystyrene is obtained by anion exchange of a chloromethylstyrene-styrene copolymer after quaternary ammonium.

[0007] According to the application, by introducing the organic anion quaternary ammonium salt modified polystyrene into the polystyrene matrix, the antistatic performance of the material can be significantly improved, and the performance remains stable during long-term use, thereby reducing the problems of dust adsorption, discharge interference and appearance degradation caused by static accumulation.

[0008] Specifically, polystyrene as the main resin has good transparency, rigidity and processing formability, and can provide a stable physical skeleton and appearance performance; on this basis, chloromethylstyrene units are introduced into the copolymerization with styrene to form a chloromethylstyrene-styrene copolymer, which provides an active benzyl chloromethyl group for subsequent quaternization, ensuring that the cationic group can be fixed on the polymer main chain in a chemical bond manner. Through the quaternization reaction, the chloromethyl structure is converted into a quaternary ammonium salt structure, which gives the polymer a fixed positive charge site. Compared with traditional physical blending type small molecule antistatic agents, the quaternary ammonium salt structure is not migratory or lost, which fundamentally solves the problem of effect attenuation caused by easy scrubbing and dissolution of surface antistatic agents; After the exchange reaction with the organic anion metal salt, the small anion in the quaternary ammonium salt structure is replaced by the organic anion. The introduced organic anion usually has the characteristics of large volume, high degree of charge delocalization and uniform polarity distribution, which makes its combination with the quaternary ammonium cation in the polymer matrix more loose. Such loose ions can not only effectively inhibit strong ion association and prevent the charge from being localized and fixed, but also reduce the tendency of anion migration and aggregation in the material, so that the material can form a continuous and stable charge dissipation path; as a result, the surface resistance of the material is significantly reduced, and the stable antistatic effect can still be maintained under conditions such as humidity, cleaning or long-term aging.

[0009] That is, in the antistatic polystyrene provided by the application, polystyrene provides a stable skeleton and application performance; the chloromethylstyrene-styrene copolymer structure provides a chemically bonded active site; quaternization introduces a fixed positive charge center to establish a stable cationic framework inside the material; the introduction of the organic anion makes the charge dissipation path exist persistently through delocalization and volume effect; the synergistic design of this "skeleton-cation-large anion" three-level structure enables the material to have good and stable antistatic effect without the need to add conductive fillers with poor compatibility. Therefore, the antistatic polystyrene provided by the application realizes persistent and stable antistatic effect while maintaining appearance and mechanical performance.

[0010] In some embodiments, the organic anion quaternary ammonium salt modified polystyrene is prepared by the following steps: S1: obtaining a chloromethyl styrene-styrene copolymer by free radical polymerization reaction of chloromethyl styrene and styrene; S2: reacting the chloromethyl styrene-styrene copolymer with a tertiary amine compound to quaternize the chloromethyl group on the chloromethyl styrene-styrene copolymer to obtain a quaternized chloromethyl styrene-styrene copolymer; S3: performing ion exchange reaction of the quaternized chloromethyl styrene-styrene copolymer with an organic anion metal salt to exchange part of the chloride ions in the quaternized chloromethyl styrene-styrene copolymer into organic anions to obtain the organic anion quaternary ammonium salt modified polystyrene.

[0011] In some embodiments, the step S1 introduces a certain proportion of chloromethyl styrene monomer into styrene, so that the obtained copolymer not only retains the main chain segment of polystyrene, but also has reactive sites distributed in the molecular skeleton, providing uniform and stable reaction sites for subsequent quaternization reaction, thereby ensuring the uniformity of the distribution of quaternary ammonium groups in the polymer chain. The step S2 converts the chloromethyl structure into a quaternary ammonium salt structure by reaction with a tertiary amine compound. Since the quaternary ammonium salt structure is fixed on the polymer main chain by chemical bonds, it will not migrate or lose like a physically mixed antistatic agent during use, and the polymer surface can maintain long-term charge dissipation ability, improving the durability of antistatic performance. The step S3 introduces an organic anion with large volume and delocalized charge distribution by ion exchange with an organic anion metal salt. Such anions are loosely combined with quaternary ammonium cations, which can effectively inhibit the strong association of ion pairs and maintain the high charge conduction ability of the charged groups in the polymer matrix. Compared with traditional small anion systems, the introduced large organic anions are less likely to migrate and aggregate inside the material, thus further improving the stability of antistatic performance and avoiding the problem of resistance rebound after heating, moisture or cleaning.

[0012] Therefore, by the above steps S1-S3, the application not only uniformly introduces cationic functional groups into the molecular skeleton, but also stabilizes them by selecting appropriate organic anions, forming an antistatic system of "immobilized quaternary ammonium cation-large volume organic anion" combination, thereby making the material have more stable and persistent antistatic effect.

[0013] In some embodiments, the step S1 comprises: 100 parts of styrene, 5-10 parts of chloromethylstyrene, 0.3-1 part of an initiator and 0.1-0.2 part of a chain transfer agent are dispersed in 100-200 parts of toluene, and reacted at 65-75°C for 6-10 hours under a nitrogen atmosphere to obtain a chloromethylstyrene-styrene copolymer.

[0014] In some embodiments described above, the amount of chloromethylstyrene monomer is controlled at 5-10 parts based on 100 parts of styrene, which can introduce a sufficient number of reactive sites in the polymer chain to make the subsequent quaternization reaction uniform, while avoiding the increase of polymer brittleness or the decrease of compatibility caused by the excessive proportion of chloromethyl monomer; the amount of initiator is in the range of 0.3-1 part, which can more effectively control the polymerization rate and molecular weight distribution; the amount of chain transfer agent is 0.1-0.2 parts, which can further optimize the molecular weight distribution to make the obtained copolymer more suitable for subsequent dissolution and modification; and 100-200 parts of toluene is selected as the solvent, and the reaction is carried out at 65-75°C for 6-10 hours under a nitrogen atmosphere, which is conducive to ensuring the smooth progress of free radical polymerization, reducing side reactions and premature crosslinking, obtaining a chloromethylstyrene-styrene copolymer with uniform distribution and stability, which is more suitable for subsequent quaternization reaction, thereby more conducive to improving the antistatic performance of the material. As an example, p-chloromethylstyrene is used as chloromethylstyrene in an embodiment of the present application.

[0015] In some embodiments, the step S2 comprises: 100 parts of chloromethylstyrene-styrene copolymer, 3-10 parts of a tertiary amine compound and 0.1-0.5 parts of an accelerator are dispersed in 400-1000 parts of N,N-dimethylformamide, and reacted at 55-65°C for 10-16 hours under a nitrogen atmosphere to obtain a quaternized chloromethylstyrene-styrene copolymer.

[0016] In some of the above embodiments, the chloromethylstyrene-styrene copolymer, as a reaction substrate, has a uniform benzyl chloromethyl group distributed in the molecular skeleton, and can undergo a nucleophilic substitution reaction with a tertiary amine compound under mild conditions to efficiently introduce a quaternary ammonium cation group; based on 100 parts of the chloromethylstyrene-styrene copolymer, the amount of the tertiary amine compound is controlled in the range of 3-10 parts, which can ensure efficient quaternization reaction and reduce side reactions or residual problems caused by excessive amine; the amount of the accelerator is 0.1-0.5 parts, which can significantly accelerate the reaction rate, improve the quaternization efficiency, and make the quaternary ammonium salt structure on the polymer chain more uniform; N,N-dimethylformamide as a high-polarity solvent can fully dissolve the substrate and amine reagent to ensure the reaction to proceed homogeneously; the reaction temperature is controlled in the range of 55-65°C and the time is 10-16h, which can not only ensure the smooth substitution reaction of chloromethyl group, but also avoid the degradation or crosslinking of the polymer chain at high temperature. Through reasonable control of the above conditions, a modified polystyrene structure containing a uniform quaternary ammonium cation group can be obtained, thereby providing a stable precursor for subsequent anion exchange and ensuring the durability and stability of the final material's antistatic performance.

[0017] In some embodiments, the tertiary amine compound includes triethylamine and N-methyl piperidine, and the mass ratio of the triethylamine and N-methyl piperidine is (3-5):1.

[0018] In some of the above embodiments, the inventors found that when triethylamine and N-methyl piperidine are used in combination and the mass ratio of the two is controlled in the range of (3-5):1, the antistatic performance of the obtained quaternized polystyrene is more stable; the reason may be that the triethylamine molecule has a small volume and strong nucleophilicity, which can quickly undergo a substitution reaction with the benzyl chloromethyl group to ensure the conversion rate and reaction efficiency of quaternization; while the N-methyl piperidine molecule has a larger volume, and the quaternary ammonium cation formed has a stronger steric hindrance effect, which can weaken the strong combination of cations and anions, and avoid excessive association of ion pairs; when the two are used in combination, on the one hand, the triethylamine ensures efficient reaction and high substitution degree, and on the other hand, the appropriate addition of N-methyl piperidine can introduce a volume effect, making the quaternary ammonium salt structure more uniform and the ion pairs looser, and finally forming a more stable charge dissipation path, so that the organic anion quaternary ammonium salt modified polystyrene can make the material have better antistatic effect.

[0019] In some embodiments, the step S3 comprises: dispersing 100 parts of the quaternized chloromethylstyrene-styrene copolymer and 5-10 parts of the organic anion metal salt in 300-600 parts of acetonitrile / N,N-dimethylformamide mixed solvent, and reacting at 20-40°C for 8-16h to obtain the organic anion quaternary ammonium salt modified polystyrene.

[0020] In some of the above embodiments, based on 100 parts of quaternary ammonium chloromethyl styrene-styrene copolymer, the amount of organic anion metal salt is controlled in the range of 5-10 parts, which can effectively introduce the target organic anion while reducing the ion residues in the system caused by excessive salt; the solvent is selected as a mixture of acetonitrile and N,N-dimethylformamide, which can not only swell or dissolve the modified polymer and the salt, but also facilitate precipitation and purification after the reaction, and obtain a more uniform structure of the organic anion modified product; the reaction is carried out at 20-40℃ for 8-16h, which is conducive to the ion exchange process and improves the conversion rate of ion exchange. Through reasonable control of the above conditions, the organic anion quaternary ammonium salt modified polystyrene with more uniform anion distribution and higher exchange efficiency can be obtained, so that the antistatic polystyrene has better antistatic effect.

[0021] In some embodiments, the organic anion metal salt comprises an organic anion comprising at least one of bis(trifluoromethane)sulfonimide anion (TFSI - ), trifluoromethanesulfonate anion (OTf - ).

[0022] In some of the above embodiments, the inventors found that, compared with common organic anions such as hexafluorophosphate or tetrafluoroborate, TFSI - and OTf - exhibit more excellent comprehensive advantages in the antistatic polystyrene system; such anions have the characteristics of large volume, high degree of charge delocalization and strong chemical stability, and can form a more loose and uniform ion pair structure with quaternary ammonium cations, so that the material exhibits more durable and stable antistatic effect during use; at the same time, the thermal stability and chemical resistance of TFSI - and OTf - are superior to those of other organic anions, and they are not easy to decompose or undergo side reactions under the processing conditions of melt extrusion, avoiding the degradation, discoloration or fluctuation of antistatic performance of the polymer caused by the instability of the anion during processing; thus, the preferred organic anion system of the present application not only improves the stability of the antistatic performance of the final material, but also significantly enhances the adaptability and controllability during processing, and is more suitable for actual industrial application.

[0023] In some embodiments, the organic anion comprises bis(trifluoromethane)sulfonimide anion and trifluoromethanesulfonate anion, and the molar ratio of the bis(trifluoromethane)sulfonimide anion to the trifluoromethanesulfonate anion is (2-3):1.

[0024] In some of the above embodiments, the inventors found that, when TFSI - and OTf -When the two are compounded in a molar ratio of (2~3):1, the antistatic polystyrene obtained has better antistatic effect; the reason may be that: TFSI - has a large volume and a high degree of charge delocalization, which is conducive to the construction of a stable ion dispersion network, but when TFSI - is used alone, it may form an excessively loose charge distribution due to the weak interionic force, resulting in insufficient continuity of the charge dissipation path; OTf - has a relatively small structure and is more likely to coordinate closely with the quaternary ammonium cation, thereby improving the stability of the ion pair and being more conducive to the formation of a continuous and stable charge dissipation link, but when OTf - is used alone, although the initial antistatic effect is good, it is easy to form an unstable distribution under humid and hot conditions, resulting in insufficient antistatic performance retention; thus, when the two are compounded in the above-mentioned ratio, the volume effect of TFSI - ensures the freedom of charge migration, and the moderate coordination effect of OTf - allows the ion pairs to form a continuous and stable charge dissipation link, thereby realizing the synergistic enhancement of the antistatic performance and making the antistatic polystyrene have better antistatic effect.

[0025] In some embodiments, the weight average molecular weight of the polystyrene is 100000~1000000. Based on the above-mentioned embodiments, this molecular weight range can ensure that the material has suitable processing fluidity while maintaining good mechanical properties.

[0026] In some embodiments, the initiator includes azobisisobutyronitrile. Based on the above-mentioned embodiments, azobisisobutyronitrile can generate stable free radicals under suitable conditions and efficiently initiate the copolymerization reaction of styrene and chloromethylstyrene.

[0027] In some embodiments, the chain transfer agent includes dodecyl mercaptan. Based on the above-mentioned embodiments, dodecyl mercaptan can effectively control the molecular weight distribution of the polymer, reduce the generation of long-chain polymers, and reduce the problems of excessively high melt strength and poor dispersibility during processing.

[0028] In some embodiments, the promoter includes KI. Based on the above-mentioned embodiments, KI can improve the reactivity of chloromethyl in the nucleophilic substitution reaction, promote the departure of chloride ions, thereby speeding up the quaternization process and improving the reaction efficiency.

[0029] In some embodiments, the raw material further comprises 0.05-0.5 parts of an antioxidant, the antioxidant comprising at least one of antioxidant 1076 and antioxidant 1010. Based on the above embodiments, the introduction of the antioxidant can effectively inhibit the chain scission or discoloration of the polymer caused by oxidation during high-temperature melt processing and long-term use, thereby improving the appearance stability and the persistence of the antistatic performance of the material during long-term service.

[0030] In a second aspect, the present application provides a method for preparing an antistatic polystyrene, comprising: providing the raw material of the antistatic polystyrene according to any one of the embodiments of the first aspect; melt blending the raw material to obtain the antistatic polystyrene.

[0031] According to the present application, by using melt blending to prepare, the organic anion quaternary ammonium salt modified polystyrene can be uniformly dispersed in the polystyrene without affecting the mechanical properties and transparency of the polystyrene matrix, thereby ensuring the stable distribution of the antistatic groups in the material and avoiding the performance degradation problem caused by the poor compatibility and easy migration of traditional small molecule antistatic agents. The method is simple in process and suitable for conventional industrial processing equipment such as extrusion and injection molding, and has good operability and promotional value.

[0032] Compared with the prior art, the present application has at least the following beneficial effects: by introducing the organic anion quaternary ammonium salt modified polystyrene into the polystyrene matrix, the antistatic performance can be kept stable for a long time and will not rapidly decay due to the migration, loss or environmental factors of the small molecule antistatic agent; at the same time, the preferred tertiary amine compound is used for quaternary ammonium reaction, which helps to improve the modification effect and thereby enhance the antistatic performance of the material; the preferred organic anion has good thermal stability and chemical resistance during processing, avoiding decomposition or side reactions under melt extrusion conditions, so that the material is suitable for industrial preparation and can maintain excellent antistatic performance in long-term use, and the transparency and mechanical properties of the polystyrene itself are maintained. DETAILED DESCRIPTION

[0033] Each embodiment in the specification is described in a progressive manner, and each embodiment focuses on the difference from other embodiments.

[0034] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "exemplary embodiment", "example", "specific example", or "some examples" and the like means that the specific feature, structure, material or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present application. The exemplary expressions of the above terms in the present specification do not necessarily refer to the same embodiment or example. Also, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0035] In addition, the terms "first", "second" are used only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Thus, the features defined with "first", "second" can include at least one of the features, explicitly or implicitly. In the description of the present application, the meaning of "a plurality of" is at least two, for example, two, three, etc., unless otherwise specifically limited.

[0036] In the description of the present specification, "parts" means "mass parts" unless otherwise specifically described.

[0037] Hereinafter, the embodiments of the present application will be described. The embodiments described below are exemplary and are for the purpose of explanation of the present application only, and cannot be understood as a limitation on the present application. In the embodiments, the specific techniques or conditions not noted are performed in accordance with the techniques or conditions described in the literature in the art or in accordance with the product manual. The reagents or instruments not noted for the manufacturer are all conventional products that can be obtained by purchase in the market.

[0038] p-Chloromethylstyrene, CAS No. 1592-20-7; N-Methylpiperidine, CAS No. 626-67-5; Polystyrene, weight average molecular weight about 300000.

[0039] Preparation Example 1 Preparation of organic anion quaternary ammonium salt-modified polystyrene: S1: In a reactor equipped with a mechanical stirrer, a condenser and a nitrogen protection device, 100 parts of styrene, 8 parts of p-chloromethylstyrene, 0.5 parts of azobisisobutyronitrile and 0.15 parts of dodecyl mercaptan were added, and 150 parts of toluene were added as a solvent. After the system was bubbled for 30 min under a nitrogen atmosphere to remove oxygen, the reaction was carried out at 70°C for 8 h. After the reaction was completed, the reaction solution was poured into excess methanol to precipitate, and was suction filtered and vacuum dried to obtain a chloromethylstyrene-styrene copolymer; S2: 100 parts of the above chloromethylstyrene-styrene copolymer was weighed out, dissolved in 500 parts of N,N-dimethylformamide, 6 parts of triethylamine and 1.5 parts of N-methylpiperidine were added, and then 0.3 parts of KI was added as an accelerator. The system was stirred at 60°C for 12 hours under a nitrogen atmosphere. After the reaction was completed, the solution was poured into anhydrous diethyl ether to precipitate, filtered, and vacuum dried to obtain a quaternized chloromethylstyrene-styrene copolymer. S3: 100 parts of the above quaternized chloromethylstyrene-styrene copolymer was taken, dispersed in 400 parts of acetonitrile / DMF (volume ratio 4:1) mixed solvent, and 8 parts of an organic anion metal salt (organic anion metal salt is a mixture of lithium bis(trifluoromethane)sulfonimide and lithium trifluoromethanesulfonate with a molar ratio of 2.5:1) was added. The reaction system was stirred at 30°C for 12 hours. After the anion exchange was completed, the solution was poured into anhydrous diethyl ether for further precipitation. The solid was collected, filtered, and vacuum dried to obtain an organic anion quaternary ammonium salt modified polystyrene A.

[0040] Preparation Example 2 Preparation of organic anion quaternary ammonium salt modified polystyrene: The same as Preparation Example 1, except that step S2 is different, specifically: S2: 100 parts of the above chloromethylstyrene-styrene copolymer was weighed out, dissolved in 500 parts of N,N-dimethylformamide, 6 parts of triethylamine and 1.5 parts of N-methylpiperidine were added, and then 0.3 parts of KI was added as an accelerator. The system was stirred at 60°C for 12 hours under a nitrogen atmosphere. After the reaction was completed, the solution was poured into anhydrous diethyl ether to precipitate, filtered, and vacuum dried to obtain a quaternized chloromethylstyrene-styrene copolymer.

[0041] Preparation Example 3 Preparation of organic anion quaternary ammonium salt modified polystyrene: The same as Preparation Example 1, except that step S2 is different, specifically: S2: 100 parts of the above chloromethylstyrene-styrene copolymer was weighed out, dissolved in 500 parts of N,N-dimethylformamide, 6 parts of triethylamine and 1.5 parts of N-methylpiperidine were added, and then 0.3 parts of KI was added as an accelerator. The system was stirred at 60°C for 12 hours under a nitrogen atmosphere. After the reaction was completed, the solution was poured into anhydrous diethyl ether to precipitate, filtered, and vacuum dried to obtain a quaternized chloromethylstyrene-styrene copolymer.

[0042] Preparation Example 4 Preparation of organic anion quaternary ammonium salt modified polystyrene: The same as Preparation Example 1, except that step S3 is different, specifically: S3: Take the above-mentioned quaternary ammonium chloromethyl styrene-styrene copolymer 100 parts, dispersed in acetonitrile / DMF (volume ratio 4:1) mixed solvent 400 parts, add 8 parts of organic anion metal salt (organic anion metal salt is lithium bis(trifluoromethane) sulfonimide), the reaction system is stirred at 30℃ for 12h, after the anion exchange is completed, the solution is poured into anhydrous ether for further precipitation, the solid is collected, filtered and vacuum dried, to obtain organic anion quaternary ammonium salt modified polystyrene D.

[0043] Preparation Example 5 Preparation of organic anion quaternary ammonium salt modified polystyrene: It is basically the same as Preparation Example 1, the only difference is that step S3 is different, specifically: S3: Take the above-mentioned quaternary ammonium chloromethyl styrene-styrene copolymer 100 parts, dispersed in acetonitrile / DMF (volume ratio 4:1) mixed solvent 400 parts, add 8 parts of organic anion metal salt (organic anion metal salt is lithium bis(trifluoromethane) sulfonimide), the reaction system is stirred at 30℃ for 12h, after the anion exchange is completed, the solution is poured into anhydrous ether for further precipitation, the solid is collected, filtered and vacuum dried, to obtain organic anion quaternary ammonium salt modified polystyrene D.

[0044] Preparation Example 6 Preparation of organic anion quaternary ammonium salt modified polystyrene: It is basically the same as Preparation Example 1, the only difference is that step S3 is different, specifically: S3: Take the above-mentioned quaternary ammonium chloromethyl styrene-styrene copolymer 100 parts, dispersed in acetonitrile / DMF (volume ratio 4:1) mixed solvent 400 parts, add 8 parts of organic anion metal salt (organic anion metal salt is lithium bis(trifluoromethane) sulfonimide), the reaction system is stirred at 30℃ for 12h, after the anion exchange is completed, the solution is poured into anhydrous ether for further precipitation, the solid is collected, filtered and vacuum dried, to obtain organic anion quaternary ammonium salt modified polystyrene D.

[0045] Comparative Preparation Example 1 Preparation of quaternary ammonium chloromethyl styrene-styrene copolymer: S1: In a reactor equipped with a mechanical stirrer, a condenser and a nitrogen protection device, add styrene 100 parts, p-chloromethylstyrene 8 parts, azobisisobutyronitrile 0.5 parts and dodecyl mercaptan 0.15 parts, and add toluene 150 parts as solvent, the system is deoxygenated by bubbling under nitrogen atmosphere for 30 min, then reacted at 70℃ for 8h, after the reaction is completed, the reaction liquid is poured into excess methanol for precipitation, filtered and vacuum dried, to obtain chloromethyl styrene-styrene copolymer; S2: 100 parts of the above chloromethylstyrene-styrene copolymer was weighed out, dissolved in 500 parts of N,N-dimethylformamide, 6 parts of triethylamine, 1.5 parts of N-methylpiperidine were added, and 0.3 parts of KI was further added as an accelerator, and the system was stirred at 60°C for 12 hours under a nitrogen atmosphere. After the reaction was completed, the solution was poured into anhydrous diethyl ether to precipitate, filtered, and vacuum dried to obtain a quaternary ammonium chloromethylstyrene-styrene copolymer.

[0046] Example 1 Preparation of antistatic polystyrene: After 100 parts of polystyrene, 10 parts of organic anion quaternary ammonium salt modified polystyrene A were dried, 0.2 parts of antioxidant 1010 was premixed, and then transferred into a twin-screw extruder for melt extrusion. The temperature of each temperature zone from the feeding section to the die head section was set to 190°C, 200°C, 205°C, 210°C, 210°C, and 210°C, respectively, and the rotation speed was 200 rpm. Antistatic polystyrene was obtained by extrusion.

[0047] Example 2 Preparation of antistatic polystyrene: The preparation was substantially the same as in Example 1, except that organic anion quaternary ammonium salt modified polystyrene B was used instead of organic anion quaternary ammonium salt modified polystyrene A.

[0048] Example 3 Preparation of antistatic polystyrene: The preparation was substantially the same as in Example 1, except that organic anion quaternary ammonium salt modified polystyrene C was used instead of organic anion quaternary ammonium salt modified polystyrene A.

[0049] Example 4 Preparation of antistatic polystyrene: The preparation was substantially the same as in Example 1, except that organic anion quaternary ammonium salt modified polystyrene D was used instead of organic anion quaternary ammonium salt modified polystyrene A.

[0050] Example 5 Preparation of antistatic polystyrene: The preparation was substantially the same as in Example 1, except that organic anion quaternary ammonium salt modified polystyrene E was used instead of organic anion quaternary ammonium salt modified polystyrene A.

[0051] Example 6 Preparation of antistatic polystyrene: The preparation was substantially the same as in Example 1, except that organic anion quaternary ammonium salt modified polystyrene F was used instead of organic anion quaternary ammonium salt modified polystyrene A.

[0052] Comparative Example 1 Preparation of antistatic polystyrene: The same as Example 1, except that the quaternary ammonium chloromethylstyrene-styrene copolymer obtained from Comparative Preparation 1 was used instead of the organic anion quaternary ammonium salt modified polystyrene A.

[0053] Test Part Surface resistivity test: the antistatic polystyrene obtained from each example and comparative example was injection molded to obtain a sample with a thickness of 2±0.2mm and a size of 100mm×100mm, and after vacuum drying at 50~60℃ for 2h and standing at 23±2℃, 50±5%RH for 48h, the surface resistivity R1(Ω / □) of the sample was tested using an ultra-high resistance micro-current tester (using concentric ring electrodes, with an outer ring diameter of 60mm and an inner ring diameter of 30mm), and the results are shown in Table 1.

[0054] Hygrothermal aging surface resistivity: after the sample subjected to the surface resistivity test was placed at 85℃±2℃, 85%±5%RH for 72h, it was taken out and placed at 23±2℃, 50±5%RH for another 4h, and then the surface resistivity R2(Ω / □) of the sample was tested using an ultra-high resistance micro-current tester (using concentric ring electrodes, with an outer ring diameter of 60mm and an inner ring diameter of 30mm), and the results are shown in Table 1.

[0055] Table 1

[0056] According to Table 1, each example exhibits significantly lower initial surface resistivity R1 and smaller surface resistivity R2 after hygrothermal aging compared to Comparative Example 1, indicating that the antistatic polystyrene provided by the present application can achieve stable and long-lasting antistatic performance while maintaining transparency and processability; the possible reason is that in Comparative Example 1, the quaternary ammonium salt structure only contains chloride ions, and the small anion forms a strong associated ion pair with the quaternary ammonium cation, which not only has insufficient initial charge dissipation ability, but also has serious chloride ion migration and agglomeration under hygrothermal conditions, resulting in a significant increase in resistivity and a significant attenuation of antistatic performance. In contrast, the large volume and delocalized organic anion in the examples of the present application replaces the chloride ion, significantly weakening the ion pair association and forming a continuous charge dissipation path, thereby significantly improving the antistatic performance of the material.

[0057] According to Examples 1~3, the modification system using triethylamine and N-methylpiperidine as quaternary ammonium reagents (Example 1, Example 3) exhibits lower resistivity and better hygrothermal retention, and the antistatic effect is better than that of the system using only triethylamine (Example 2); this indicates that the ratio of the tertiary amine complex has an important influence on the steric hindrance and uniformity of the quaternized group, and in addition, when the mass ratio of triethylamine to N-methylpiperidine is close to 4:1 (Example 1), the material obtained has better antistatic effect.

[0058] According to the embodiments 1, 4-6, it is known that the modification effects of different organic anions have obvious differences. In the embodiment 4, only bis(trifluoromethane) sulfonimide anion is used, and the most stable resistivity after damp heat aging is shown; in the embodiment 6, only triflate anion is used, and the initial resistivity is the lowest, but the rising amplitude after damp heat aging is larger; in the embodiment 5, 1:1 compound of the two is used, and the initial performance is better, but the damp heat retention is still not as good as that of the embodiment 4; in comparison, in the embodiment 1, the compound ratio of bis(trifluoromethane) sulfonimide and triflate anion is 2.5:1, and the initial antistatic performance and damp heat stability are taken into account, and the comprehensive performance is the best, and the material obtained has better antistatic effect.

[0059] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An antistatic polystyrene, characterized by, Raw materials including the following mass parts: 100 parts of polystyrene, 5-15 parts of organic anion quaternary ammonium salt modified polystyrene; The organic anion quaternary ammonium salt modified polystyrene is obtained by anion exchange of chloromethylstyrene-styrene copolymer after quaternary ammonium salt modification.

2. The antistatic polystyrene according to claim 1, characterized in that, The organic anion quaternary ammonium salt modified polystyrene is prepared by the following steps: S1: obtaining chloromethylstyrene-styrene copolymer by free radical polymerization reaction of chloromethylstyrene and styrene; S2: reacting the chloromethylstyrene-styrene copolymer with a tertiary amine compound to cause quaternary ammonium salt reaction of chloromethyl on the chloromethylstyrene-styrene copolymer to obtain quaternary ammonium salt chloromethylstyrene-styrene copolymer; S3: ion exchange reaction of the quaternary ammonium salt chloromethylstyrene-styrene copolymer with organic anion metal salt to exchange part of the chloride in the quaternary ammonium salt chloromethylstyrene-styrene copolymer into organic anion to obtain organic anion quaternary ammonium salt modified polystyrene.

3. The antistatic polystyrene according to claim 2, characterized in that, The step S1 includes: dispersing 100 parts of styrene, 5-10 parts of chloromethylstyrene, 0.3-1 parts of initiator and 0.1-0.2 parts of chain transfer agent in 100-200 parts of toluene, reacting for 6-10 h under nitrogen atmosphere at 65-75℃ to obtain chloromethylstyrene-styrene copolymer.

4. The antistatic polystyrene according to claim 2, characterized in that, The step S2 includes: dispersing 100 parts of chloromethylstyrene-styrene copolymer, 3-10 parts of tertiary amine compound and 0.1-0.5 parts of accelerator in 400-1000 parts of N,N-dimethylformamide, reacting for 10-16 h under nitrogen atmosphere at 55-65℃ to obtain quaternary ammonium salt chloromethylstyrene-styrene copolymer.

5. The antistatic polystyrene according to claim 4, characterized in that, The tertiary amine compound includes triethylamine and N-methylpiperidine, and the mass ratio of the triethylamine and N-methylpiperidine is (3-5):

1.

6. The antistatic polystyrene according to claim 2, characterized in that, The step S3 includes: dispersing 100 parts of quaternary ammonium salt chloromethylstyrene-styrene copolymer and 5-10 parts of organic anion metal salt in 300-600 parts of acetonitrile / N,N-dimethylformamide mixed solvent, reacting for 8-16 h at 20-40℃ to obtain organic anion quaternary ammonium salt modified polystyrene.

7. The antistatic polystyrene according to claim 6, characterized in that, The organic anion metal salt includes organic anion, and the organic anion includes at least one of bis(trifluoromethane)sulfonimide anion and trifluoromethanesulfonate anion.

8. The antistatic polystyrene according to claim 7, characterized in that, The organic anion includes bis(trifluoromethane)sulfonimide anion and trifluoromethanesulfonate anion, and the molar ratio of the bis(trifluoromethane)sulfonimide anion and trifluoromethanesulfonate anion is (2-3):

1.

9. The antistatic polystyrene according to any one of claims 1 to 8, characterized in that, The raw materials meet at least one of the following conditions: 1) the weight average molecular weight of the polystyrene is 100000-1000000; 2) the initiator includes azobisisobutyronitrile; 3) the chain transfer agent includes dodecyl mercaptan; 4) the accelerator includes KI; 5) the raw materials further include: 0.05-0.5 parts of antioxidant, and the antioxidant includes at least one of antioxidant 1076 and antioxidant 1010.

10. A method of preparing an antistatic polystyrene, characterized by, includes: To provide a raw material for the antistatic polystyrene according to any one of claims 1-9; Melt blend the raw material to obtain the antistatic polystyrene.

Images