Modified polystyrene composite material containing flame-retardant rubber and preparation method thereof

Abstract

The invention relates to the technical field of polystyrene, and discloses a modified polystyrene composite material containing flame-retardant rubber and a preparation method thereof. The preparation method comprises the following steps: by taking p-toluenesulfonic acid as a catalyst, preparing a flame retardant from 5 '-phenyl-[1, 1': 3 ', 1 '']-4, 4''-terphenyl dicarboxylic acid, double-end hydroxypropyl silicone oil and 2-carboxyethyl phenyl glycol phosphinate, and then adding the flame retardant into a mixture of polystyrene and silicone rubber to obtain the modified polystyrene composite material containing flame-retardant rubber. The flame retardant disclosed by the invention contains a phosphorus element, a siloxane structure and a triphenylbenzene structure, is beneficial to improving the combustion char-forming capability of polystyrene, and has very high flame retardant property. The flame retardant contains a plurality of side-group benzene ring structures, and the double-end hydroxypropyl silicone oil has a chemical structure similar to that of silicone rubber, so that the flame retardant can be used as a compatilizer, the compatibility between the silicone rubber and polystyrene is improved, and the material has better mechanical properties.

Description

Technical Field

[0001] The present invention relates to the technical field of polystyrene, in particular to a modified polystyrene composite material containing flame retardant rubber and a preparation method thereof. Background Art

[0002] Polystyrene (PS) is widely used in packaging, electronics, and construction due to its lightweight, easy-to-process, and low-cost properties. However, its poor toughness, low impact strength, and flammability limit its application in high-end applications. Currently, research on polystyrene modification focuses on two main areas: improving its impact strength and toughness by adding rubber; and improving its flame retardancy by introducing flame retardants.

[0003] Silicone rubber has high toughness, good mechanical properties, and certain flame retardant properties. When added to polymer materials such as polystyrene, it can improve the mechanical and flame retardant properties of the material. However, the poor compatibility between silicone rubber and polystyrene can easily cause phase separation, further weakening the material performance. The development of polystyrene composite materials that are both highly effective in flame retardancy, mechanically reinforced, and environmentally friendly has become a research hotspot. Patent No. CN117447805B discloses grafting low-phenyl silicone rubber materials onto the main chain of polystyrene thermoplastic elastomers, so that the material has good low-temperature resistance, heat resistance, chemical solvent resistance and other properties. However, this patent does not solve the problem of poor flame retardancy of polystyrene. Summary of the Invention

[0004] (1) Technical problems solved: In view of the deficiencies in the prior art, the present invention provides a modified polystyrene composite material containing flame retardant rubber and a preparation method thereof, which solves the problems of poor flame retardancy and low impact strength of polystyrene.

[0005] (II) Technical Solution: A method for preparing a modified polystyrene composite material containing flame retardant rubber is as follows: Step (1), tetrahydrofuran, water, an inorganic base in a ratio of (60-80) mmol:10 mmol:(22-24) mmol:(0.36-0.48) mmol, 3,5-dibromobiphenyl, 4-carboxyphenylboric acid, and tetrakis(triphenylphosphine)palladium are added to a flask, heated to 70-90°C in a nitrogen atmosphere, refluxed for 12-24 hours, diluted with water, and then extracted with dichloromethane. The organic phase is dried by adding anhydrous sodium sulfate, filtered, and then distilled under reduced pressure. The product is washed with petroleum ether and then recrystallized from dichloromethane to obtain 5'-phenyl-[1,1':3',1"]-4,4''-terphenyldicarboxylic acid.

[0006] Step (2), in an ice-water bath, add N,N-dimethylformamide, double-terminated hydroxypropyl silicone oil in a ratio of 100g: (6.1-8.5)g: (10-13.8)g: (0.26-0.35)g, 2-carboxyethylphenylphosphinate glycol, 5'-phenyl-[1,1':3',1"]-4,4''-terphenyldicarboxylic acid, and p-toluenesulfonic acid into a flask, stir and react at 100-110°C for 18-24h, condense and reflux during the reaction, then add ethanol, stir to precipitate, filter, wash the filter cake with ethanol, and dry to obtain a flame retardant.

[0007] Step (3): uniformly mixing silicone rubber, a vulcanizing agent, a catalyst, a flame retardant, and polystyrene in a ratio of (10-25) g: (0.4-1.2) g: (0.01-0.03) g: (6-15) g: 100 g on a twin-roll mill, pelletizing the mixture using a twin-screw extruder, and forming a sample using an injection molding machine after drying to obtain a modified polystyrene composite material containing flame retardant rubber.

[0008] Furthermore, the inorganic base in step (1) is sodium carbonate or potassium carbonate.

[0009] Furthermore, in step (2), the temperature of the twin-screw extruder is 150-190° C., and the rotation speed is 300-450 rpm.

[0010] Furthermore, in step (2), the temperature of the injection molding machine is 190-200° C., and the pressure is 40-50 MPa.

[0011] Furthermore, in step (3), the vulcanizing agent is ethyl orthosilicate or methyltributylidene oxime silane; and the catalyst is dibutyltin dilaurate.

[0012] (3) Beneficial technical effects: The present invention uses p-toluenesulfonic acid as a catalyst to carry out an esterification reaction on 5'-phenyl-[1,1':3',1"]-4,4''-terphenyldicarboxylic acid, double-terminated hydroxypropyl silicone oil, and 2-carboxyethylphenylphosphinate glycol to prepare a flame retardant, which is then added to a mixture of polystyrene and silicone rubber to obtain a modified polystyrene composite material containing flame retardant rubber.

[0013] The 5'-phenyl-[1,1':3',1"]-4,4''-terphenyl dicarboxylic acid and the flame retardant prepared therefrom contain multiple side-group benzene ring structures, can generate strong π-π interactions with polystyrene, and have excellent compatibility with polystyrene. In addition, the double-terminated hydroxypropyl silicone oil has a similar chemical structure to silicone rubber, so the flame retardant can be used as a compatibilizer to improve the compatibility between silicone rubber and polystyrene, thereby giving the material better mechanical properties.

[0014] The flame retardant of the present invention contains flame-retardant phosphorus elements and siloxane structures, as well as triphenylbenzene structures with high carbonization properties, which are beneficial to improving the combustion carbonization ability of polystyrene and have a very high limiting oxygen index and flame retardant properties. DETAILED DESCRIPTION

[0015] As shown in the following examples, practical and presently preferred embodiments of the present invention are illustrated. However, those skilled in the art will appreciate that modifications and improvements can be made within the spirit and scope of the present invention in light of this disclosure.

[0016] 2-Carboxyethylphenylphosphinate was prepared according to the method of the document "Synthesis Research of 2-Carboxyethylphenylphosphinate" in the journal "Synthesis Technology and Applications" Volume 36, Issue 2, June 2021, with the structural formula: .

[0017] The following double-terminated hydroxypropyl silicone oil is model YC-0323, with an average molecular weight of 2000, and is sourced from Wuhan Yuancheng Chemical Co., Ltd. The silicone rubber is 107 silicone rubber, sourced from Jinan Juyang Chemical Technology Co., Ltd. The polystyrene is model GP33, sourced from Suzhou Tiantao Plastics Co., Ltd.

[0018] Example 1: A method for preparing a modified polystyrene composite material containing flame retardant rubber is as follows: S1. Add 200 mL of tetrahydrofuran, 20 mL of water, 60 mmol of potassium carbonate, 10 mmol of 3,5-dibromobiphenyl, 24 mmol of 4-carboxyphenylboric acid, and 0.36 mmol of tetrakis(triphenylphosphine)palladium to a flask. Heat to 90° C. in a nitrogen atmosphere, reflux for 12 h, add water to dilute, then extract with dichloromethane, add anhydrous sodium sulfate to the organic phase for drying, filter, and distill under reduced pressure. Wash the product with petroleum ether and then recrystallize it from dichloromethane to obtain 5'-phenyl-[1,1':3',1"]-4,4''-terphenyldicarboxylic acid. The reaction formula for the preparation is: .

[0019] S2. In an ice-water bath, add 2 L of N,N-dimethylformamide, 200 g of double-ended hydroxypropyl silicone oil, 12.2 g of 2-carboxyethylphenylphosphinate, 20 g of 5'-phenyl-[1,1':3',1"]-4,4''-terphenyldicarboxylic acid, and 0.52 g of p-toluenesulfonic acid to a flask, and stir at 110°C for 18 h. During the reaction, condense and reflux. Then, add ethanol, stir to separate out the precipitate, filter, wash the filter cake with ethanol, and dry to obtain a flame retardant.

[0020] S3. On a twin-roll mill, 100 g of silicone rubber, 12 g of tetraethyl orthosilicate, 0.1 g of dibutyltin dilaurate, 60 g of a flame retardant, and 1 kg of polystyrene were uniformly mixed and granulated using a twin-screw extruder. The temperatures of each section of the twin-screw extruder were 150° C., 170° C., 190° C., 185° C., and 160° C., and the speed was 300 rpm. After drying, samples were prepared using an injection molding machine. The temperature of the injection molding machine was 190° C., and the pressure was 50 MPa to obtain a modified polystyrene composite material containing flame retardant rubber.

[0021] Example 2: A method for preparing a modified polystyrene composite material containing flame retardant rubber is as follows: S1. Add 300 mL of tetrahydrofuran, 40 mL of water, 80 mmol of sodium carbonate, 10 mmol of 3,5-dibromobiphenyl, 22 mmol of 4-carboxyphenylboric acid, and 0.48 mmol of tetrakis(triphenylphosphine)palladium to a flask. Heat to 70 ° C. in a nitrogen atmosphere, reflux for 24 hours, add water to dilute, then extract with dichloromethane, add anhydrous sodium sulfate to the organic phase for drying, filter, and evaporate under reduced pressure. Wash the product with petroleum ether and then recrystallize it from dichloromethane to obtain 5'-phenyl-[1,1':3',1"]-4,4''-terphenyldicarboxylic acid.

[0022] S2. In an ice-water bath, add 2.5 L N,N-dimethylformamide, 200 g double-ended hydroxypropyl silicone oil, 17 g 2-carboxyethylphenylphosphinate glycol, 25 g 5'-phenyl-[1,1':3',1"]-4,4''-terphenyldicarboxylic acid, and 0.61 g p-toluenesulfonic acid to a flask, and stir the mixture at 100°C for 24 h. Condensate and reflux during the reaction, then add ethanol, stir to separate out the precipitate, filter, wash the filter cake with ethanol, and dry to obtain a flame retardant.

[0023] S3. On a twin-roll mill, 210 g of silicone rubber, 4 g of methyl tributylidene oxime silane, 0.3 g of dibutyltin dilaurate, 90 g of a flame retardant, and 1 kg of polystyrene were uniformly mixed and granulated using a twin-screw extruder. The temperatures of each section of the twin-screw extruder were 150° C., 170° C., 190° C., 185° C., and 160° C., and the speed was 450 rpm. After drying, samples were made using an injection molding machine. The temperature of the injection molding machine was 200° C. and the pressure was 40 MPa to obtain a modified polystyrene composite material containing flame retardant rubber.

[0024] Example 3: A method for preparing a modified polystyrene composite material containing flame retardant rubber is as follows: S1. Prepare 5'-phenyl-[1,1':3',1"]-4,4''-terphenyldicarboxylic acid according to the method of Example 1.

[0025] S2. In an ice-water bath, add 2.3 L N,N-dimethylformamide, 200 g double-ended hydroxypropyl silicone oil, 15 g 2-carboxyethylphenylphosphinate glycol, 27.6 g 5'-phenyl-[1,1':3',1"]-4,4''-terphenyldicarboxylic acid, and 0.7 g p-toluenesulfonic acid to a flask, and stir to react at 105°C for 22 h. Condensate and reflux during the reaction, then add ethanol, stir to precipitate, filter, wash the filter cake with ethanol, and dry to obtain a flame retardant.

[0026] S3. On a twin-roll mill, 250 g of silicone rubber, 8 g of tetraethyl orthosilicate, 0.2 g of dibutyltin dilaurate, 120 g of a flame retardant, and 1 kg of polystyrene were uniformly mixed and granulated using a twin-screw extruder. The temperatures of each section of the twin-screw extruder were 150° C., 170° C., 190° C., 185° C., and 160° C., and the speed was 375 rpm. After drying, samples were prepared using an injection molding machine. The temperature of the injection molding machine was 190° C. and the pressure was 50 MPa to obtain a modified polystyrene composite material containing flame retardant rubber.

[0027] Example 4: A method for preparing a modified polystyrene composite material containing flame retardant rubber is as follows: S1. Prepare 5'-phenyl-[1,1':3',1"]-4,4''-terphenyldicarboxylic acid according to the method of Example 1.

[0028] S2. In an ice-water bath, add 2.2 L N,N-dimethylformamide, 200 g double-ended hydroxypropyl silicone oil, 13.5 g 2-carboxyethylphenylphosphinate glycol, 24 g 5'-phenyl-[1,1':3',1"]-4,4''-terphenyldicarboxylic acid, and 0.65 g p-toluenesulfonic acid to a flask, and stir the mixture at 100°C for 21 h. Condensate and reflux during the reaction, then add ethanol, stir to separate out the precipitate, filter, wash the filter cake with ethanol, and dry to obtain a flame retardant.

[0029] S3. On a twin-roll mill, 160 g of silicone rubber, 12 g of methyl tributylidene oxime silane, 0.2 g of dibutyltin dilaurate, 150 g of flame retardant, and 1 kg of polystyrene were uniformly mixed and granulated using a twin-screw extruder. The temperatures of each section of the twin-screw extruder were 150° C., 170° C., 190° C., 185° C., and 160° C., and the speed was 350 rpm. After drying, samples were made using an injection molding machine. The temperature of the injection molding machine was 200° C. and the pressure was 50 MPa to obtain a modified polystyrene composite material containing flame retardant rubber.

[0030] The difference between Comparative Example 1 and Example 1 is that no flame retardant is added: S1. 100 g of silicone rubber, 12 g of ethyl orthosilicate, 0.1 g of dibutyltin dilaurate, and 1 kg of polystyrene were uniformly mixed on a twin-roll mill and granulated using a twin-screw extruder with section temperatures of 150° C., 170° C., 190° C., 185° C., and 160° C. at a speed of 300 rpm. After drying, samples were prepared using an injection molding machine with a temperature of 190° C. and a pressure of 50 MPa to obtain a polystyrene composite material.

[0031] The difference between Comparative Example 2 and Example 1 is that 5'-phenyl-[1,1':3',1"]-4,4''-terphenyldicarboxylic acid is not added: S1. In an ice-water bath, add 2 L of N,N-dimethylformamide, 200 g of double-ended hydroxypropyl silicone oil, 12.2 g of 2-carboxyethylphenylphosphinate glycol, and 0.52 g of p-toluenesulfonic acid into a flask, and stir at 110°C for 18 h. During the reaction, condense and reflux. Then, add ethanol, stir to separate out the precipitate, filter, wash the filter cake with ethanol, and dry to obtain a flame retardant.

[0032] S2. 100 g of silicone rubber, 12 g of tetraethyl orthosilicate, 0.1 g of dibutyltin dilaurate, 60 g of flame retardant, and 1 kg of polystyrene were uniformly mixed on a twin-roll mill and granulated using a twin-screw extruder. The temperatures of each section of the twin-screw extruder were 150° C., 170° C., 190° C., 185° C., and 160° C., and the speed was 300 rpm. After drying, samples were prepared using an injection molding machine. The temperature of the injection molding machine was 190° C., and the pressure was 50 MPa to obtain a polystyrene composite material.

[0033] The difference between Comparative Example 3 and Example 1 is that biphenyl dicarboxylic acid is used instead of 5'-phenyl-[1,1':3',1"]-4,4''-terphenyl dicarboxylic acid: S1. In an ice-water bath, add 2 L of N,N-dimethylformamide, 200 g of double-ended hydroxypropyl silicone oil, 12.2 g of 2-carboxyethylphenylphosphinate, 20 g of biphenyldicarboxylic acid (CAS No. 787-70-2, purchased from Zibo Yujin Trading Co., Ltd.), and 0.52 g of p-toluenesulfonic acid into a flask. Stir and react at 110°C for 18 h. During the reaction, condense and reflux. Then, add ethanol and stir to separate out the precipitate. Filter, wash the filter cake with ethanol, and dry to obtain a flame retardant.

[0034] S2. 100 g of silicone rubber, 12 g of tetraethyl orthosilicate, 0.1 g of dibutyltin dilaurate, 60 g of flame retardant, and 1 kg of polystyrene were uniformly mixed on a twin-roll mill and granulated using a twin-screw extruder. The temperatures of each section of the twin-screw extruder were 150° C., 170° C., 190° C., 185° C., and 160° C., and the speed was 300 rpm. After drying, samples were prepared using an injection molding machine. The temperature of the injection molding machine was 190° C., and the pressure was 50 MPa to obtain a polystyrene composite material.

[0035] The Izod impact strength of polystyrene composites is tested according to GB / T 1843-2008. The tensile properties are tested according to GB / T 1040.1-2018. The limiting oxygen index is tested according to GB / T 2406.1-2008.

[0036] Table 1 Mechanical properties and flame retardant properties of polystyrene composites

[0037] Compared with Comparative Example 1, Examples 1-4 use 5'-phenyl-[1,1':3',1"]-4,4''-terphenyl dicarboxylic acid, double-terminated hydroxypropyl silicone oil, and 2-carboxyethylphenyl phosphinate glycol to carry out an esterification reaction to prepare a flame retardant, which is then added to a mixture of polystyrene and silicone rubber, significantly improving the mechanical properties and flame retardant properties of the polystyrene composite material, such as the cantilever beam impact strength, elongation at break, and limiting oxygen index. This is mainly because 5'-phenyl-[1,1':3',1"]-4,4''-terphenyl dicarboxylic acid and the flame retardant prepared therefrom contain multiple side benzene ring structures, which can produce a strong π-π interaction with polystyrene and have good compatibility with polystyrene. In addition, the double-terminated hydroxypropyl silicone oil has a similar chemical structure to silicone rubber, so that the flame retardant can be used as a compatibilizer to improve the compatibility between silicone rubber and polystyrene, giving the material better mechanical properties. The flame retardant contains flame retardant phosphorus and siloxane structure, as well as triphenylbenzene with high carbonization property ( ) structure, which is beneficial to improving the combustion charring ability and flame retardant properties of polystyrene and has a very high limiting oxygen index.

[0038] Comparative Example 2 does not add 5'-phenyl-[1,1':3',1"]-4,4''-terphenyl dicarboxylic acid, and Comparative Example 3 uses biphenyl dicarboxylic acid instead of 5'-phenyl-[1,1':3',1"]-4,4''-terphenyl dicarboxylic acid. The flame retardants prepared by the two do not contain a large number of side benzene ring structures, and the π-π interaction between them and polystyrene is low. The compatibility with polystyrene is poor, and it is difficult to use it as a compatibilizer to improve the compatibility between silicone rubber and polystyrene, resulting in low mechanical properties such as impact strength of the two materials. In addition, the flame retardant does not contain triphenylbenzene with high carbonization property, and its combustion carbonization ability is weak. The limiting oxygen index of the two materials is low, and the flame retardant performance is poor.

[0039] Those skilled in the art will appreciate that the concepts and specific embodiments disclosed in the foregoing description can be easily used as a basis for modifying or designing other embodiments that achieve the same purpose as the present invention. Those skilled in the art will also appreciate that such equivalent embodiments do not depart from the spirit and scope of the present invention as set forth in the appended claims.

Claims

1. A method for preparing a modified polystyrene composite material containing flame retardant rubber, characterized in that: The preparation method is as follows: Step (1), in an ice-water bath, add N,N-dimethylformamide, double-terminated hydroxypropyl silicone oil, 2-carboxyethylphenylphosphinate glycol, 5'-phenyl-[1,1':3',1"]-4,4''-terphenyldicarboxylic acid, and p-toluenesulfonic acid to a flask, stir and react at 100-110°C for 18-24h, then add ethanol, stir to precipitate, filter, wash the filter cake, and dry to obtain a flame retardant; Step (2): uniformly mixing the silicone rubber, vulcanizing agent, catalyst and flame retardant on a twin-roll mill, then mixing with polystyrene in a high-speed mixer, granulating with a twin-screw extruder, and sampling with an injection molding machine after drying to obtain a modified polystyrene composite material containing flame retardant rubber.

2. The method for preparing a modified polystyrene composite material containing flame retardant rubber according to claim 1, characterized in that: In the step (1), the ratio of double-terminated hydroxypropyl silicone oil, 2-carboxyethylphenyl phosphinate glycol, 5'-phenyl-[1,1':3',1"]-4,4''-terphenyldicarboxylic acid, and p-toluenesulfonic acid is 100g: (6.1-8.5)g: (10-13.8)g: (0.26-0.35)g.

3. The method for preparing a modified polystyrene composite material containing flame retardant rubber according to claim 1, wherein: The preparation method of 5'-phenyl-[1,1':3',1"]-4,4''-terphenyldicarboxylic acid in step (1) is as follows: tetrahydrofuran, water, inorganic base, 3,5-dibromobiphenyl, 4-carboxyphenylboric acid, and tetrakis(triphenylphosphine)palladium are added to a flask, heated to 70-90°C in a nitrogen atmosphere, refluxed for 12-24h, extracted and washed the product, and recrystallized to obtain 5'-phenyl-[1,1':3',1"]-4,4''-terphenyldicarboxylic acid.

4. The method for preparing a modified polystyrene composite material containing flame retardant rubber according to claim 3, characterized in that: The ratio of the inorganic base, 3,5-dibromobiphenyl, 4-carboxyphenylboric acid and tetrakis(triphenylphosphine)palladium is (60-80) mmol:10 mmol:(22-24) mmol:(0.36-0.48) mmol.

5. The method for preparing a modified polystyrene composite material containing flame retardant rubber according to claim 4, characterized in that: The inorganic base is sodium carbonate or potassium carbonate.

6. The method for preparing a modified polystyrene composite material containing flame retardant rubber according to claim 1, characterized in that: In the step (2), the vulcanizing agent is ethyl orthosilicate or methyltributylidene oxime silane; and the catalyst is dibutyltin dilaurate.

7. The method for preparing a modified polystyrene composite material containing flame retardant rubber according to claim 1, wherein: In the step (2), the ratio of silicone rubber, vulcanizing agent, catalyst, flame retardant and polystyrene is (10-25) g: (0.4-1.2) g: (0.01-0.03) g: (6-15) g: 100 g.

8. The method for preparing a modified polystyrene composite material containing flame retardant rubber according to claim 1, characterized in that: In step (2), the temperature of the twin-screw extruder is 150-190° C., and the speed of the twin-screw is 300-450 rpm.

9. The method for preparing a modified polystyrene composite material containing flame retardant rubber according to claim 1, wherein: In step (2), the temperature of the injection molding machine is 190-200° C. and the pressure is 40-50 MPa.

10. A modified polystyrene composite material containing flame retardant rubber obtained by the preparation method according to any one of claims 1 to 9.

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