A process for the preparation of inherently flame-retardant, toughened polystyrene copolymers

Abstract

The application discloses a preparation method of an intrinsically flame-retardant and toughened polystyrene copolymer, and comprises the following steps: preparing a phosphorus-nitrogen integrated functional compound by using glycine, polyformaldehyde and dimethyl phosphite as raw materials; performing acyl chloride modification on the phosphorus-nitrogen integrated functional compound by using sulfoxide chloride; preparing a high-flexibility flame-retardant monomer by reacting the acyl chloride modified phosphorus-nitrogen integrated functional compound with a phenolic hydroxyl cardanol; and finally preparing the polystyrene copolymer by reacting the high-flexibility flame-retardant monomer with styrene. The copolymer has both flame-retardant and toughening advantages.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of preparation method of intrinsic flame-retardant, toughening polystyrene copolymer. BACKGROUND

[0002] Polystyrene (PS) is the world's top five thermoplastic polymers in the range of application, in recent years, the consumption of polystyrene in our country is basically one-third of the global, and still increasing at a rate of 3%-4% per year. Polystyrene has good chemical resistance, dimensional stability and transparency, widely used in optical instruments, ornaments, packaging containers, electrical industry, electronic packaging industry and construction industry, etc.

[0003] However, the content of carbon and hydrogen elements in the molecular structure of polystyrene is high, which is highly flammable, and the limiting oxygen index (LOI) is only 18. During the combustion process, it produces dense black smoke, which has fire safety hazards. In addition, the large number of rigid benzene ring groups on the side chain also cause polystyrene to have the characteristics of high brittleness and poor toughness, which is easy to crack under stress during use. These shortcomings greatly limit the application of polystyrene. Therefore, the research on flame retardation and toughening of polystyrene materials not only helps to reduce the harm caused by combustion, but also has important theoretical guidance and practical significance for improving the comprehensive performance and expanding the application field.

[0004] The most commonly used flame retardant for polystyrene is traditional additive brominated flame retardant. However, with the increasing environmental pressure, there is an increasing demand for more environmentally friendly halogen-free flame retardants in the market. Moreover, the addition of flame retardants through simple physical addition method will further damage the mechanical properties of polystyrene. In view of this, the present application provides a halogen-free, environmentally friendly, intrinsic flame-retardant and toughening polystyrene copolymer without adding ingredients. SUMMARY

[0005] The present application is aimed at the shortcomings of traditional polystyrene "flammable" and "brittle", and prepares a polystyrene copolymer with flame-retardant and toughening effects.

[0006] To achieve the above-mentioned purpose, the preparation method of intrinsic flame-retardant, toughening polystyrene copolymer according to the present application comprises the following steps: first, preparing a phosphorus-nitrogen integrated functional compound with glycine, polyformaldehyde and dimethyl phosphite as raw materials; then, acyl chlorination modification of the phosphorus-nitrogen integrated functional compound with thionyl chloride; then, reaction of the acyl chlorination modified phosphorus-nitrogen integrated functional compound with phenolic hydroxyl cashew phenol to obtain a high-flexibility flame-retardant monomer; finally, reaction of the high-flexibility flame-retardant monomer with styrene to obtain the intrinsic flame-retardant, toughening polystyrene copolymer.

[0007] The preparation method of intrinsic flame-retardant, toughening polystyrene copolymer according to the present application comprises the following specific operation steps:

[0008] (1) mixing paraformaldehyde, glycine and tetrahydrofuran and heating to 60-70℃, then adding dimethyl phosphite dropwise, and continuing to heat after the dropwise addition is completed until the reaction is complete; after the reaction is completed, removing the solvent tetrahydrofuran to obtain a light yellow viscous liquid, which is a phosphorus-nitrogen integrated functional compound; the phosphorus-nitrogen integrated functional compound is designated as HOOC-NP2.

[0009] (2) dissolving the phosphorus-nitrogen integrated functional compound in a solvent and adding a catalyst, and adding sulfurous chloride dropwise at a temperature of 0-15℃; after the dropwise addition is completed, heating to 70-80℃ and continuing to heat at the temperature until the reaction is complete to prepare a product solution; adding saturated brine and a sodium hydroxide solution to the product solution to wash the product solution, then separating the inorganic phase, adding anhydrous sodium sulfate to the organic phase to dry, after the drying is completed, solid-liquid separation, removing the solvent from the liquid product obtained by the solid-liquid separation to obtain an acyl chloride modified flame-retardant functional monomer; the mass concentration of the sodium hydroxide solution is 5%, after the washing is completed, the organic phase and the inorganic phase are separated by standing and layering, then the inorganic phase is separated out to retain the organic phase.

[0010] (3) mixing phenolic hydroxyl cashew phenol (CAS: 501-26-8) with a solvent and adding triethylamine, dissolving the acyl chloride modified flame-retardant functional monomer in a solvent to prepare a flame-retardant functional monomer solution, and adding the flame-retardant functional monomer solution dropwise at a temperature of -5℃, after the dropwise addition is completed, first performing a low-temperature reaction at a temperature of -10-0℃, then continuing to heat at a temperature of 5-15℃ until the reaction is complete; after the reaction is completed, filtering to obtain a liquid crude product, washing the liquid crude product with acetic acid solution, NaOH solution and saturated brine in sequence, then drying with anhydrous sodium sulfate, after the drying is completed, solid-liquid separation to obtain a product solution, removing the solvent from the product solution to obtain a light yellow viscous liquid, which is a high-flexibility flame-retardant monomer; the mass concentrations of the acetic acid solution and the NaOH solution are 2% and 10% respectively; the washing and drying operations are as follows: adding acetic acid solution to the liquid crude product to wash, after the washing is completed, standing and layering to separate out the inorganic phase to retain the organic phase; then adding NaOH solution to the organic phase to wash, after the washing is completed, standing and layering to separate out the inorganic phase to retain the organic phase; then adding saturated brine to the organic phase to wash, after the washing is completed, standing and layering to separate out the inorganic phase to retain the organic phase; finally, adding anhydrous sodium sulfate to the organic phase to dry, after the drying is completed, solid-liquid separation;

[0011] (4) mixing styrene, high-flexibility flame-retardant monomer and solvent, adding initiator dropwise under temperature 65-80℃ and nitrogen protection, and keeping temperature 65-80℃ after dropwise addition is completed until reaction is completed; liquid mixture containing polystyrene copolymer crude product is obtained after reaction is completed; dropwise addition time is 20-40 minutes, and reaction is completed generally in 4-8 hours;

[0012] (5) adding liquid mixture into ethanol to make solid product precipitate; solid product is vacuum dried after solid-liquid separation, and light yellow solid obtained after drying is completed is intrinsic flame-retardant, toughened polystyrene copolymer; temperature of vacuum drying is 70℃.

[0013] The molar ratio of the glycine, paraformaldehyde and dimethyl phosphite is 1.0-1.2:2.0-4.0:4.0.

[0014] After removing the solvent tetrahydrofuran in the step (1), the following treatment is needed: first washing with a small amount of water, then drying with anhydrous sodium sulfate, and finally solid-liquid separation; the light yellow viscous liquid obtained after solid-liquid separation is the phosphorus-nitrogen integrated functional compound. The operation of washing and drying is as follows: after washing with water, the liquid is separated into inorganic phase and organic phase, and then anhydrous sodium sulfate is added to the organic phase for drying.

[0015] In the steps (1), (2) and (3), the dropwise addition speed is 1-2 seconds / drop; in the step (1), the time for continuing to keep temperature after dropwise addition is completed is 7-9 hours; in the step (2), the time for continuing to keep temperature after dropwise addition is completed is 1-2 hours; in the step (3), the time for low-temperature reaction and keeping temperature after dropwise addition is completed is 7-9 hours.

[0016] In the step (2), the molar ratio of the thionyl chloride to the phosphorus-nitrogen integrated functional compound is 1.1-1.2:1.

[0017] In the step (2), the catalyst is N,N-dimethylformamide (DMF), n-dodecyl trimethylammonium chloride, pyridine or triethylamine; the catalyst dosage is 3-6% of the mass of the thionyl chloride.

[0018] In the step (3), the molar ratio of the phenolic hydroxyl cardanol to the acyl chloride modified flame-retardant functional monomer is 1:1.0-1.2; the dosage of triethylamine is 0.5-1.2 times of the mass of the phenolic hydroxyl cardanol.

[0019] In the step (4), the mass ratio of the styrene to the high-flexibility flame-retardant monomer is 1:0.2-2.

[0020] The initiator in the step (4) is one or more than two of azobisisobutyronitrile, azobisisoheptyl nitrile and dibenzoyl peroxide, and the amount of the initiator is 3-10% of the mass of the styrene.

[0021] The solvent in the step (2) is dichloroethane or chloroform; the solvent in the step (3) is dichloroethane or chloroform; and the solvent in the step (4) is dichloromethane, dichloroethane, chloroform, cyclohexane or 1,4-dioxane, preferably cyclohexane or 1,4-dioxane.

[0022] The amount of the tetrahydrofuran used as the solvent in the step (1) is the lower limit for completely dissolving the paraformaldehyde and the glycine in the reaction process, but the amount of the tetrahydrofuran can be appropriately increased for the purpose of smooth flow of the system during stirring and more balanced reaction in the system. In the same way, the amount of the solvent in the steps (2), (3) and (4) is also the lower limit for completely dissolving the raw materials, but the amount of the solvent in the steps (2), (3) and (4) can be appropriately increased for the purpose of smooth flow of the system during stirring and more balanced reaction in the system.

[0023] The reaction process of the step (1) is shown in the following formula:

[0024] .

[0025] The reaction processes of the steps (2) and (3) are shown in the following formula:

[0026] .

[0027] The reaction process of the step (4) is shown in the following formula:

[0028] .

[0029] The product prepared by the method has the advantages of both flame retardation and toughening, on the one hand, the flame retardation function of the copolymer is derived from the rich flame retardant groups in the high phosphorus content flame retardant with reactive functional groups, the phosphorus content is rich, halogen-free and environmentally friendly, the carbonization rate is high, and the toughening effect is derived from the large amount of flexible groups in the flame retardant functional monomer and the large amount of flexible chain segments in the cardanol. The essential flame-retardant polystyrene copolymer can freely adjust the ratio of the flame-retardant groups, the cardanol and the styrene, and the performance of the polystyrene copolymer is optimal at a reasonable ratio. The product can be directly used as a polystyrene product with good flame retardation and mechanical properties, or can be used as a flame retardant additive, has high flame retardant efficiency, long-lasting effect, and no problems such as easy volatilization, migration and precipitation, and has wide application value. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1The infrared spectrum of the product obtained in step (1) of Example 1;

[0031] Figure 2 The nuclear magnetic resonance spectrum of the product obtained in step (1) of Example 1. DETAILED DESCRIPTION

[0032] The following examples illustrate the practicability of the technical solutions of the present application, and the protection scope of the present application should not be limited to the following specific examples. Example 1

[0033] (1) In a three-necked flask with stirring device, thermometer and reflux condenser, 252 g (2.8 mol) of polyformaldehyde, 152 g (2.0 mol) of glycine and 400 mL of tetrahydrofuran were added, the reaction mixture was stirred and heated to 66°C, and then 440 g (4.0 mol) of dimethyl phosphite was slowly added dropwise at 1-2 seconds per drop; after the addition was completed, the reaction was continued at about 66°C for 8 hours, after the reaction was completed, the solvent was removed by rotary evaporation to obtain a crude product, the crude product was washed with 60 mL of water, and after washing, the layers were separated by standing, the inorganic phase was separated, and anhydrous sodium sulfate was added to the organic phase for drying, and after drying, the product was filtered under suction to obtain a light yellow transparent liquid 782 g, which was a phosphorus-nitrogen integrated functional compound (HOOC-NP2);

[0034] (2) In a 500 ml three-necked flask with stirring device, thermometer and reflux condenser, 329 g (1.0 mol) of HOOC-NP2 and 150 mL of dichloroethane were added, 6.0 g of DMF was added as a catalyst, the temperature was kept at about 10°C, 130.9 g (1.1 mol) of thionyl chloride was slowly added dropwise into the reaction flask at 1-2 seconds per drop, after the addition was completed, the product solution was obtained by heating and slowly warming to 75°C under stirring, and the reaction was continued at 75°C for 1.5 h; after the reaction was completed, saturated brine and 5% sodium hydroxide solution were added to the product solution for washing, after washing, the layers were separated by standing, the inorganic phase was separated, and anhydrous sodium sulfate was added to the organic phase for drying, and after suction filtration, a dichloroethane solution of the acyl chloride modified flame-retardant functional monomer was obtained, and the solvent dichloroethane was removed by rotary evaporation to obtain the acyl chloride modified flame-retardant functional monomer (ClOC-NP2);

[0035] (3) 30.25 g (0.1 mol) of commercially available phenolic hydroxyl cashew phenol was mixed with 100 ml of dichloroethane solvent and added to a reaction bottle, and 20.2 g (0.2 mol) of triethylamine was added, and 234.55 g (0.1 mol) of ClOC-NP prepared above was dissolved in 50 ml of dichloroethane at a constant temperature of -5°C, and was added to the reaction bottle at a drop rate of 2 drops / s, and after the drop was completed, the reaction was kept at low temperature for 8 h, and then the temperature was raised to 10°C, and the reaction was continued for 8 h to complete the reaction. After the reaction was completed, the liquid crude product was filtered, and the liquid crude product was sequentially washed with 2% acetic acid solution, 10% NaOH solution, and saturated brine, and then dried with anhydrous sodium sulfate, and finally solid-liquid separation was performed, and the solvent was removed by rotary evaporation to obtain a light yellow viscous liquid, which was a high-flexibility flame-retardant monomer;

[0036] (4) In a 500 ml three-necked flask with stirring device, thermometer and reflux condenser device, 24 g of styrene, 12 g of high-flexibility flame-retardant monomer and 120 g of 1,4-dioxane were added and mixed, and nitrogen protection and magnetic stirring were carried out, and in this process, the temperature was slowly raised to the set temperature of 65°C. After the temperature reached the set temperature, a mixed solution of azobisisobutyronitrile and azobisisoheptyl nitrile initiator (1.5 g of initiator dissolved in 15 ml of dioxane) was slowly added, and the drop was completed in about 0.5 h. After the drop was completed, the reaction was kept for 6-8 h, and a liquid mixture containing a crude product of polystyrene copolymer was obtained after the reaction was completed;

[0037] (5) The liquid mixture was poured into ethanol to make the solid product precipitate, and the solid product was separated and dissolved in dichloromethane, and then poured into ethanol to make the solid product precipitate, and the solid product was separated and dried at 70°C under vacuum for 5 hours, and after the drying was completed, a light yellow solid was obtained, which was a flame-retardant and toughening polystyrene copolymer, denoted as polystyrene copolymer-I. Example 2

[0038] (1) In a three-necked flask with stirring device, thermometer and reflux condenser device, 252 g (2.8 mol) of polyformaldehyde, 152 g (2.0 mol) of glycine and 400 mL of tetrahydrofuran were added, and the reaction mixture was stirred and heated to 66°C, and then 440 g (4.0 mol) of dimethyl phosphite was slowly added dropwise at 1-2 drops per second within 1 hour; after the drop was completed, the reaction was continued at about 66°C for 8 hours, and after the reaction was completed, the solvent was removed by rotary evaporation to obtain a crude product, which was washed with 60 mL of water, and after the washing, the layers were separated, the inorganic phase was separated, and anhydrous sodium sulfate was added to the organic phase for drying, and after the drying, the product was filtered, and a light yellow transparent liquid 782 g was obtained, which was a phosphorus-nitrogen integrated functional compound (HOOC-NP2);

[0039] (2) In a 500ml three-necked flask with stirring device, thermometer and reflux condenser, 329g (1.0mol) HOOC-NP2 and 100 mL dichloroethane were added, 7.0g DMF was added as catalyst, the temperature was kept at about 10℃, 142.8g (1.2mol) of thionyl chloride was slowly added into the reaction flask, 1-2 seconds per drop, after the addition was completed, the product solution was obtained after heating and slowly warming to 75℃ under stirring, the reaction was continued for 1.5h at 75℃; the product solution was washed with saturated brine and 5% NaOH solution, after washing, the layers were separated, the inorganic phase was separated and anhydrous sodium sulfate was added to the organic phase for drying, after suction filtration, the acyl chloride modified flame-retardant functional monomer dichloroethane solution was obtained, and dichloroethane was removed by rotary evaporation to obtain the acyl chloride modified flame-retardant functional monomer (ClOC-NP2);

[0040] (3) The commercially available phenolic hydroxyl cardanol 30.25g (0.1mol) was mixed with 100ml dichloroethane solvent and added to the reaction flask, and 20.2g (0.2mol) triethylamine was added, at a constant temperature of -5℃, the ClOC-NP2 34.55g (0.1mol) prepared above was dissolved in 50ml dichloroethane, and was added to the reaction flask at a drop rate of 2 drops / s, after the addition was completed, the reaction was kept at low temperature for 6h, then the temperature was raised to 15℃, and the reaction was continued for 6h; after the reaction was completed, the liquid crude product was obtained by filtration, the liquid crude product was washed with 2% acetic acid solution, 10% NaOH solution, saturated brine, and then dried with anhydrous sodium sulfate, finally solid-liquid separation was carried out, and the solvent was removed by rotary evaporation to obtain a light yellow viscous liquid, which was the high flexibility flame-retardant monomer;

[0041] (4) In a 500ml three-necked flask with stirring device, thermometer and reflux condenser, 28g of styrene, 8g of high flexibility flame-retardant monomer and 120g of 1,4-dioxane were mixed and mixed, and nitrogen protection and magnetic stirring were carried out, and the temperature was slowly raised to the set temperature of 65℃ during the process. After the temperature reached the set temperature, the azobisisobutyronitrile and azobisisoheptyl nitrile initiator mixed solution (1.5g initiator dissolved in 15ml dioxane) was slowly added, and the dropwise addition was completed in about 0.5h, after the dropwise addition was completed, the reaction was kept for 6-8h, and the liquid mixture containing the crude product of polystyrene copolymer was obtained after the reaction was completed;

[0042] (5) The liquid mixture was poured into ethanol to make the solid product precipitate, the solid product was separated and dissolved in dichloromethane, then poured into ethanol to make the solid product precipitate, the solid product was separated and dried at 70℃ under vacuum for 5 hours, and the light yellow solid obtained after drying was the intrinsic flame-retardant and toughening polystyrene copolymer, which was recorded as polystyrene copolymer-II. Example 3

[0043] (1) In a three-necked flask with stirring device, thermometer and reflux condenser, 252 g (2.8 mol) of polyformaldehyde, 152 g (2.0 mol) of glycine and 400 mL of tetrahydrofuran were added, the reaction mixture was stirred and heated to 66°C, then 440 g (4.0 mol) of dimethyl phosphite was slowly added dropwise at 1-2 seconds per drop; after the addition was completed, the reaction was continued at about 66°C for 8 hours, after the reaction was completed, the solvent was removed by rotary evaporation to obtain a crude product, the crude product was washed with 60 mL of water, and after washing, the layers were separated, the inorganic phase was separated and anhydrous sodium sulfate was added to the organic phase for drying, and after drying, filtration was performed to obtain 782 g of a light yellow transparent liquid, which was a phosphorus-nitrogen integrated functional compound (HOOC-NP2);

[0044] (2) In a 500 ml three-necked flask with stirring device, thermometer and reflux condenser, 329 g (1.0 mol) of HOOC-NP2 and 100 mL of dichloroethane were added, 7.0 g of DMF was added as a catalyst, the temperature was maintained at about 10°C, and 142.8 g (1.2 mol) of thionyl chloride was slowly added dropwise into the reaction flask at 1-2 seconds per drop, after the addition was completed, the mixture was heated and slowly warmed to 75°C under stirring, and the reaction was continued at 75°C for 1.5 h; after the reaction was completed, the product solution was obtained, saturated brine and 5% sodium hydroxide solution were added to the product solution for washing, and after washing, the layers were separated, the inorganic phase was separated and anhydrous sodium sulfate was added to the organic phase for drying, and after filtration, a dichloroethane solution of the acyl chloride modified flame-retardant functional monomer was obtained, and dichloroethane was removed by rotary evaporation to obtain the acyl chloride modified flame-retardant functional monomer (ClOC-NP2);

[0045] (3) Commercially available phenolic hydroxyl cashew phenol 30.25 g (0.1 mol) was mixed with 100 ml of dichloroethane solvent and added to the reaction flask, and 20.2 g (0.2 mol) of triethylamine was added, at a constant temperature of -5°C, the ClOC-NP2 34.55 g (0.1 mol) prepared above was dissolved in 50 ml of dichloroethane, and was added to the reaction flask at a dropwise rate of 2 drops / s, after the addition was completed, the reaction was continued for 6 h at low temperature, then the temperature was raised to 15°C, and the reaction was continued for 6 h; after the reaction was completed, the liquid crude product was filtered, the liquid crude product was sequentially washed with 2% acetic acid solution, 10% NaOH solution, saturated brine, then dried with anhydrous sodium sulfate, and finally solid-liquid separation was performed, and the solvent was removed by rotary evaporation to obtain a light yellow viscous liquid, which was a high-flexibility flame-retardant monomer;

[0046] (4) In a 500ml three-necked flask with stirring device, thermometer and reflux condenser, 24g of styrene, 24g of high flexibility flame retardant monomer and 120g of 1,4-dioxane were added and mixed, protected by nitrogen and magnetically stirred, and the temperature was slowly increased to the set temperature of 65°C in the process. After the temperature reached the set temperature, slowly drop the mixed solution of azobisisobutyronitrile and azobisisoheptyl nitrile initiator (1.5g initiator dissolved in 15ml dioxane), about 0.5h drop completion, after drop completion, keep warm for 6-8h, after reaction completion, get liquid mixture containing crude product of polystyrene copolymer;

[0047] (5) Pour the liquid mixture into ethanol, make the solid product precipitate, separate the solid and liquid, and dissolve the precipitated solid product in dichloromethane, then pour it into ethanol to make the solid product precipitate, separate the solid product and dry it at 70°C under vacuum for 5 hours, after drying, get light yellow solid, which is intrinsic flame retardant and toughening polystyrene copolymer, recorded as polystyrene copolymer-III.

[0048] Comparative Example 4

[0049] (1) In a 500ml three-necked flask with stirring device, thermometer and reflux condenser, 36g of styrene, 120g of 1,4-dioxane solvent were mixed and added to the three-necked flask, protected by nitrogen and magnetically stirred, and the temperature was slowly increased to the set temperature of 65°C in the process. After the temperature reached the set temperature, slowly drop the mixed solution of azobisisobutyronitrile, azobisisoheptyl nitrile and dibenzoyl peroxide initiator (1.5g initiator dissolved in 15ml dioxane), about 0.5h drop completion, after drop completion, keep warm for 6-8h to complete reaction.

[0050] (2) After the reaction is completed, pour the viscous mixture solution into excess methanol to precipitate a large amount of light yellow solid. Dissolve the precipitate again in chloroform and precipitate again in excess methanol. The above dissolution, precipitation and washing cycle is repeated twice, and the final product is dried at 70°C under vacuum to obtain a pure white solid, recorded as pure polystyrene. The weight is 35.7g, and the yield is 95.3%.

[0051] LOI test: according to ISO 4589-2 combustion performance oxygen index test standard. Using a flat vulcanizing machine to press and form, respectively, polystyrene copolymer, pure polystyrene was pressed and formed into a standard plate of 100x100x3.2mm 3 , and then cut to prepare 100x6.5x3.2mm 3The test sample is 15 for each group. The oxygen concentration is changed by 0.5% each time. After the sample is tested at a certain oxygen concentration, the oxygen concentration is increased by 0.5% and the sample cannot pass the test, and the oxygen concentration is decreased by 0.5% and the sample passes the test. The low oxygen concentration is the corresponding oxygen index.

[0052] Impact resistance test: The impact resistance test is tested by using a pendulum impact testing machine (ZBC8400-A) (MTS System Co., Ltd., China) according to the GB / T 1043-93 standard, and the impact strength of a notched sample with a size of 80×10×3.2 mm 3 is determined. The sample is supported by a simply supported beam and is impacted by a single pendulum swing.

[0053] The products prepared in Examples 1-3 and Comparative Example 4 are tested according to the above test standards, and the test results are shown in the following table:

[0054]

[0055] As can be seen from the table, the results of the LOI test and the impact resistance test of the product prepared by the present application are obviously better than those of the comparative example. The flame-retardant function of the copolymer prepared by the present application is derived from the rich flame-retardant groups in the reactive high-phosphorus-content flame retardant, and the toughening effect is derived from the large number of flexible groups in the flame-retardant functional monomer and the large number of flexible segments in the cardanol. The reasonable proportion can make the properties of the polystyrene copolymer optimal.

[0056] The above is only a preferred embodiment of the present application, and does not limit the technical solutions of the present application in any form. Any equivalent replacement or partial improvement within the technical essence of the present application shall be considered within the protection scope of the present application.

Claims

1. A method for preparing an inherently flame-retardant and toughened polystyrene copolymer, characterized in that... Includes the following steps: First, a phosphorus-nitrogen integrated functional compound is prepared using glycine, paraformaldehyde, and dimethyl phosphite as raw materials. Then, the phosphorus-nitrogen integrated functional compound is modified by acyl chloride. Next, the acyl chloride-modified phosphorus-nitrogen integrated functional compound is reacted with phenolic hydroxy cashew nut shell powder to prepare a highly flexible flame-retardant monomer. Finally, the highly flexible flame-retardant monomer is reacted with styrene to prepare an inherently flame-retardant and toughened polystyrene copolymer. The molar ratio of glycine, paraformaldehyde, and dimethyl phosphite is 1.0-1.2:2.0-4.0:4.0; the molar ratio of phenolic hydroxy cashew nut shell powder to the acyl chloride-modified flame-retardant functional monomer is 1:1.0-1.2; the molar ratio of thionyl chloride to the phosphorus-nitrogen integrated functional compound is 1.1-1.2:1; and the mass ratio of styrene to the highly flexible flame-retardant monomer is 1:0.2-2.

2. The method for preparing the inherently flame-retardant and toughened polystyrene copolymer according to claim 1, characterized in that... Includes the following steps: (1) Mix paraformaldehyde, glycine and tetrahydrofuran and heat to 60-70℃, then add dimethyl phosphite dropwise. After the addition is complete, continue to keep the temperature and react until the reaction is complete. After the reaction is complete, remove the solvent tetrahydrofuran to obtain a light yellow viscous liquid, which is the phosphorus-nitrogen integrated functional compound. (2) Dissolve the phosphorus-nitrogen integrated functional compound in a solvent and add a catalyst. Add thionyl chloride dropwise at a temperature of 0-15℃. After the dropwise addition is complete, raise the temperature to 70-80℃ and continue to keep the reaction at this temperature until the reaction is complete to obtain a product solution. Add saturated saline and sodium hydroxide solution to the product solution to wash the product solution. Then separate the inorganic phase. Add anhydrous sodium sulfate to the organic phase for drying. After drying, separate the solid and liquid. Remove the solvent from the liquid product obtained from the solid-liquid separation to obtain the acyl chloride modified flame retardant functional monomer. (3) Mix phenolic hydroxy cashew phenol with solvent and add triethylamine. Dissolve the acyl chloride modified flame retardant functional monomer in solvent to prepare flame retardant functional monomer solution. Add flame retardant functional monomer solution dropwise at -10-0℃. After the addition is completed, carry out low temperature reaction at -10-0℃ first, and then continue to keep the reaction at 5-15℃ until the reaction is complete. After the reaction is completed, filter to obtain liquid crude product. Wash the liquid crude product with acetic acid solution, NaOH solution and saturated saline solution in sequence, and then dry with anhydrous sodium sulfate. After drying, separate solid and liquid to obtain product solution. Remove the solvent in product solution to obtain light yellow viscous liquid, which is high flexibility flame retardant monomer. (4) Mix styrene, high-flexibility flame-retardant monomer and solvent, and add initiator dropwise at a temperature of 65-80℃ and under nitrogen protection. After the dropwise addition is completed, keep the reaction at a temperature of 65-80℃ until the reaction is complete. After the reaction is completed, a liquid mixture containing crude polystyrene copolymer is obtained. (5) Add the liquid mixture to ethanol to allow the solid product to be fully separated; after solid-liquid separation, vacuum dry the solid product. The light yellow solid obtained after drying is the inherently flame-retardant and toughened polystyrene copolymer.

3. The method for preparing the inherently flame-retardant and toughened polystyrene copolymer according to claim 2, characterized in that: In steps (1), (2), and (3), the dropping rate is 1-2 seconds / drop; in step (1), the time for continuing the reaction at a constant temperature after the dropping is completed is 7-9 hours; in step (2), the time for continuing the reaction at a constant temperature after the dropping is completed is 1-2 hours; in step (3), the time for both the low-temperature reaction and the temperature-controlled reaction after the dropping is completed is 7-9 hours.

4. The method for preparing the inherently flame-retardant and toughened polystyrene copolymer according to claim 2, characterized in that: In step (2), the catalyst is N,N-dimethylformamide, n-dodecyltrimethylammonium chloride, pyridine, or triethylamine; the amount of catalyst used is 3-6% of the mass of thionyl chloride.

5. The method for preparing the inherently flame-retardant and toughened polystyrene copolymer according to claim 2, characterized in that: In step (3), the amount of triethylamine used is 0.5-1.2 times the mass of phenolic hydroxycainol.

6. The method for preparing the inherently flame-retardant and toughened polystyrene copolymer according to claim 2, characterized in that: In step (4), the initiator is one or more of azobisisobutyronitrile, azobisisoheptanenitrile and benzoyl peroxide in any mass ratio, and the amount of initiator is 3-10% of the mass of styrene.

7. The method for preparing the inherently flame-retardant and toughened polystyrene copolymer according to claim 2, characterized in that: In step (2), the solvent is dichloroethane or chloroform; in step (3), the solvent is dichloroethane or chloroform; in step (4), the solvent is dichloromethane, dichloroethane, chloroform, cyclohexane or 1,4-dioxane.

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