PMMA (polymethyl methacrylate) based on nitrogen-phosphorus-silicon system synergistic flame retardance and production process thereof

Abstract

The invention relates to the technical field of high polymer materials, in particular to PMMA (polymethyl methacrylate) based on nitrogen-phosphorus-silicon system synergistic flame retardance and a production process thereof. The PMMA is prepared from the following raw materials in parts by weight: 80 to 100 parts of methyl methacrylate, 0.1 to 0.25 part of compound initiator, 10 to 20 parts of synergistic flame retardant, 3 to 6 parts of release agent, 2 to 5 parts of antioxidant and 2 to 6 parts of antistatic agent; the compound initiator is prepared by compounding tert-butylperoxy-3, 5, 5-trimethyl hexanoate, di-tert-butyl peroxide and azodiisobutyronitrile according to a mass ratio of (1 to 1.3): (0.8 to 1): (1 to 1.2); the synergistic flame retardant prepared by the preparation method disclosed by the invention has excellent flame retardant property by virtue of the mutual synergistic effect among the zinc-aluminum hydrotalcite, nitrogen, phosphorus and silicon elements; when the prepared synergistic flame retardant is applied to the production process of PMMA, not only can the flame retardant property of PMMA be remarkably improved, but also the mechanical property of PMMA can be remarkably improved, and the quality of PMMA is effectively ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, in particular to PMMA with synergistic flame retardancy based on a nitrogen-phosphorus-silicon system and a production process thereof. Background Art

[0002] Polymethyl methacrylate (PMMA) is widely used in a variety of fields, including architectural decoration, optical lenses, and billboards, due to its excellent optical clarity, good mechanical strength, and easy processing. However, its flammability severely limits its application. When PMMA burns, it not only spreads flames rapidly but also releases large amounts of heat and toxic smoke, easily causing serious damage in a fire. Currently, PMMA can be flame-retarded by various methods. Additive flame retardants are added to PMMA through physical mixing, which is simple to operate but prone to uneven dispersion, leading to a decrease in the material's mechanical and optical properties. Reactive flame retardants introduce flame-retardant groups through chemical reactions, which improve compatibility. However, the synthesis process is complex and costly, and most single flame-retardant systems are difficult to meet high-standard flame-retardant requirements. In light of this situation, the present invention provides PMMA with a nitrogen-phosphorus-silicon system for synergistic flame retardancy and a production process thereof, which are used to address the above-mentioned technical problems. Summary of the Invention

[0003] The purpose of the present invention is to provide PMMA with synergistic flame retardancy based on a nitrogen-phosphorus-silicon system and a production process thereof. The prepared synergistic flame retardant has excellent flame retardant properties due to the synergistic effect between zinc-aluminum hydrotalcite and nitrogen, phosphorus, and silicon elements. The application of the prepared synergistic flame retardant in the production process of PMMA can not only significantly improve the flame retardant properties of PMMA, but also significantly enhance its mechanical properties, effectively ensuring its quality.

[0004] To achieve the above object, the present invention provides the following technical solutions: A PMMA with synergistic flame retardancy based on a nitrogen-phosphorus-silicon system comprises the following raw materials in parts by weight: 80-100 parts of methyl methacrylate, 0.1-0.25 parts of a compound initiator, 10-20 parts of a synergistic flame retardant, 3-6 parts of a release agent, 2-5 parts of an antioxidant, and 2-6 parts of an antistatic agent.

[0005] Furthermore, the preparation method of the synergistic flame retardant is as follows: pre-treated zinc-aluminum hydrotalcite is uniformly dispersed in xylene at a solid-liquid ratio of 5 to 10 g / L to prepare a dispersion; cyanoguanidine, tricresyl phosphate, and vinyltriethoxysilane are added to the dispersion at a dosage ratio of 1 to 1.2 mol / L, 1.2 to 1.4 mol / L, and 1.1 to 1.2 mol / L, respectively; after stirring and mixing at a temperature of 65 to 75°C for 50 to 80 minutes, 2 to 3% by mass of an initiator and 1.5 to 2.5% by mass of a catalyst are added to the obtained mixture, and after uniform dispersion, the mixture is kept warm for reaction at a temperature of 80 to 90°C for 5 to 8 hours; after the reaction is completed, the xylene in the product is removed by reduced pressure distillation, and then the product is washed and dried to obtain the synergistic flame retardant.

[0006] Furthermore, the preparation method of the pre-treated zinc-aluminum hydrotalcite is as follows: adding the zinc-aluminum hydrotalcite at a dosage ratio of 0.05-0.1 g / mL into a 0.08-0.12 mol / L aqueous solution of hexadecyltrimethylammonium bromide, stirring evenly, and then stirring and reacting at a temperature of 75-90°C for 3-6 hours; after the reaction is completed, the product components are sequentially subjected to solid-liquid separation, washing and drying treatment to obtain the pre-treated zinc-aluminum hydrotalcite.

[0007] Furthermore, the initiator is selected from any one of benzoyl peroxide and lauroyl peroxide.

[0008] Furthermore, the catalyst is selected from any one of pyridine, triethylamine, 4-dimethylaminopyridine, and N-methylimidazole.

[0009] Furthermore, the compound initiator is compounded by tert-butyl peroxy-3,5,5-trimethylhexanoate, di-tert-butyl peroxide and azobisisobutyronitrile in a mass ratio of 1-1.3:0.8-1:1-1.2.

[0010] Furthermore, the release agent is selected from any one of zinc stearate, montan wax, and calcium stearate.

[0011] Furthermore, the antioxidant is selected from any one of antioxidant 1010, antioxidant 168, antioxidant DLTP, and antioxidant 330.

[0012] Furthermore, the antistatic agent is selected from any one of N-hydroxymethyl acrylamide, N-(4-hydroxyphenyl) methacrylamide, N-(2-hydroxypropyl) methacrylamide, and N-(hydroxymethyl) nicotinamide.

[0013] A production process for PMMA based on a nitrogen-phosphorus-silicon system with synergistic flame retardancy comprises the following steps: Step 1: Accurately weigh all raw materials, mix and stir them evenly, and then pour them into a dipping tank. Lead the alkali-free glass fiber roving from the creel, pass through a yarn separation plate and enter a recyclable closed dipping tank equipped with a tension roller for dipping. The tension roller ensures that the angle of the alkali-free glass fiber roving when entering the preforming die is ≤2°. Step 2: After being soaked, the excess resin and bubbles are discharged through the preforming mold for preforming, and then enter the forming mold for gelation and curing; the cured product is continuously pulled out of the mold by the traction equipment at a pultrusion speed of 0.2-0.5m / min, and the final product is the PMMA finished product; Among them, the volume content of the alkali-free glass fiber roving in PMMA is 55-65%; the heating temperatures of the forming mold are: the temperature of zone one is 90-110°C, the temperature of zone two is 100-120°C, and the temperature of zone three is 100-110°C.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention involves placing zinc-aluminum hydrotalcite in an aqueous solution of cetyltrimethylammonium bromide. The long-chain alkyl groups enter the interlayers of the zinc-aluminum hydrotalcite and, through the oriented arrangement of hydrophobic chains, significantly expand the interlayer spacing, providing ample space for subsequent intercalation or grafting of organic molecules. The introduction of long-chain alkyl groups transforms the surface of the zinc-aluminum hydrotalcite from hydrophilic to hydrophobic. The resulting pre-treated zinc-aluminum hydrotalcite is more easily dispersed in polymethyl methacrylate (PMMA), reducing interfacial defects and enhancing mechanical properties. Furthermore, the quaternary ammonium salt groups in cetyltrimethylammonium bromide serve as a "bridge" for chemical grafting. Through further chemical reactions, a nitrogen-phosphorus-silicon organic composite flame retardant is successfully grafted onto the surface and interlayers of the zinc-aluminum hydrotalcite, resulting in a multi-element, multi-phase synergistic flame retardant. During combustion, nitrogen decomposes to produce non-combustible gases, diluting the oxygen concentration; phosphorus promotes carbonization, forming a barrier layer; and silicon forms a silicon-oxygen layer on the surface, enhancing the stability of the carbon layer. Zinc-aluminum hydrotalcite further enhances the flame retardant effect by decomposing, absorbing heat, releasing water vapor and forming metal oxides. This synergistic effect significantly improves the flame retardant properties of PMMA.

[0015] 2. Chemical grafting of a nitrogen-phosphorus-silicon organic composite flame retardant onto the surface and interlayers of the zinc-aluminum hydrotalcite effectively improves the compatibility of the synergistic flame retardant with the PMMA matrix and reduces the likelihood of flame retardant aggregation and migration. Compared to traditional additive flame retardants, the synergistic flame retardant prepared in this invention effectively transfers stress, significantly improving the mechanical properties of PMMA and effectively ensuring its quality.

[0016] In summary, the synergistic flame retardant prepared by the present invention exhibits superior flame retardancy thanks to the synergistic effect between zinc-aluminum hydrotalcite and nitrogen, phosphorus, and silicon. Application of this synergistic flame retardant in PMMA production not only significantly improves PMMA's flame retardancy but also significantly enhances its mechanical properties, effectively ensuring its quality. DETAILED DESCRIPTION

[0017] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0018] Example 1 A PMMA with synergistic flame retardancy based on a nitrogen-phosphorus-silicon system comprises the following raw materials in parts by weight: 80 parts of methyl methacrylate, 0.1 part of a compound initiator, 10 parts of a synergistic flame retardant, 3 parts of zinc stearate, 2 parts of antioxidant 1010, and 2 parts of N-hydroxymethyl acrylamide; the compound initiator is prepared by compounding tert-butyl peroxy-3,5,5-trimethylhexanoate, di-tert-butyl peroxide, and azobisisobutyronitrile in a mass ratio of 1:0.8:1.

[0019] The preparation method of the synergistic flame retardant is as follows: pre-treated zinc-aluminum hydrotalcite is uniformly dispersed in xylene at a solid-liquid ratio of 5 g / L to prepare a dispersion; cyanoguanidine, tricresyl phosphate, and vinyltriethoxysilane are added to the dispersion at a dosage ratio of 1 mol / L, 1.2 mol / L, and 1.1 mol / L, respectively, and stirred and mixed at a temperature of 65°C for 80 minutes. Then, 2% by weight of benzoyl peroxide and 1.5% by weight of pyridine are added to the obtained mixture, and after uniform dispersion, the mixture is kept warm at a temperature of 80°C for 8 hours. After the reaction is completed, the xylene in the product is removed by vacuum distillation, and the product is then washed and dried to obtain the synergistic flame retardant.

[0020] The preparation method of the pretreated zinc-aluminum hydrotalcite is as follows: the zinc-aluminum hydrotalcite is added into a 0.08 mol / L hexadecyltrimethylammonium bromide aqueous solution at a dosage ratio of 0.05 g / mL, stirred evenly, and then stirred and reacted at a temperature of 75°C for 6 hours; after the reaction is completed, the product components are sequentially subjected to solid-liquid separation, washing and drying treatment to obtain the pretreated zinc-aluminum hydrotalcite.

[0021] A production process for PMMA based on a nitrogen-phosphorus-silicon system with synergistic flame retardancy comprises the following steps: Step 1: Accurately weigh all the raw materials, mix and stir them evenly, and then pour them into the dipping tank. Lead the alkali-free glass fiber roving from the creel, pass through the yarn separation plate and enter the recyclable closed dipping tank equipped with a tension roller for dipping treatment; wherein, the tension roller makes the angle of the alkali-free glass fiber roving entering the preforming die be 2°; Step 2: After being soaked, the excess resin and bubbles are discharged through the preforming mold for preforming, and then enter the forming mold for gelation and curing; the cured product is continuously pulled out of the mold by the traction equipment at a pultrusion speed of 0.2m / min, and the final product is the PMMA finished product; Among them, the volume content of alkali-free glass fiber roving in PMMA is 55%; the heating temperatures of the forming mold are: the temperature of zone 1 is 90°C, the temperature of zone 2 is 100°C, and the temperature of zone 3 is 100°C.

[0022] Example 2 A PMMA with synergistic flame retardancy based on a nitrogen-phosphorus-silicon system comprises the following raw materials in parts by weight: 90 parts of methyl methacrylate, 0.15 parts of a compound initiator, 15 parts of a synergistic flame retardant, 5 parts of montan wax, 3 parts of antioxidant 168, and 4 parts of N-(4-hydroxyphenyl) methacrylamide; the compound initiator is prepared by compounding tert-butyl peroxy-3,5,5-trimethylhexanoate, di-tert-butyl peroxide, and azobisisobutyronitrile in a mass ratio of 1.2:0.9:1.1.

[0023] The preparation method of the synergistic flame retardant is as follows: pre-treated zinc-aluminum hydrotalcite is uniformly dispersed in xylene at a solid-liquid ratio of 8 g / L to prepare a dispersion; cyanoguanidine, tricresyl phosphate, and vinyltriethoxysilane are added to the dispersion at a dosage ratio of 1.1 mol / L, 1.3 mol / L, and 1.2 mol / L, respectively; after stirring and mixing at a temperature of 70°C for 60 minutes, 2.5% by mass of lauroyl peroxide and 2% by mass of triethylamine are added to the obtained mixture, and after uniform dispersion, the mixture is kept warm for reaction at a temperature of 85°C for 6 hours; after the reaction is completed, the xylene in the product is removed by vacuum distillation, and the product is then washed and dried to obtain the synergistic flame retardant.

[0024] The preparation method of the pretreated zinc-aluminum hydrotalcite is as follows: adding the zinc-aluminum hydrotalcite at a dosage ratio of 0.08 g / mL into a 0.1 mol / L hexadecyltrimethylammonium bromide aqueous solution, stirring evenly, and then stirring and reacting at a temperature of 85° C. for 5 hours; after the reaction is completed, the product components are sequentially subjected to solid-liquid separation, washing and drying treatment to obtain the pretreated zinc-aluminum hydrotalcite.

[0025] A production process for PMMA based on a nitrogen-phosphorus-silicon system with synergistic flame retardancy comprises the following steps: Step 1: Accurately weigh all the raw materials, mix and stir them evenly, and then pour them into the dipping tank. Lead the alkali-free glass fiber roving from the creel, pass through the yarn separation plate and enter the recyclable closed dipping tank equipped with a tension roller for dipping treatment; wherein, the tension roller makes the angle of the alkali-free glass fiber roving entering the preforming die be 2°; Step 2: After being soaked, the excess resin and bubbles are discharged through the preforming mold for preforming, and then enter the forming mold for gelation and curing; the cured product is continuously pulled out of the mold by the traction equipment at a pultrusion speed of 0.3m / min, and the final product is the PMMA finished product; Among them, the volume content of alkali-free glass fiber roving in PMMA is 60%; the heating temperatures of the forming mold are: the temperature of zone 1 is 100°C, the temperature of zone 2 is 110°C, and the temperature of zone 3 is 100°C.

[0026] Example 3 A PMMA with synergistic flame retardancy based on a nitrogen-phosphorus-silicon system comprises the following raw materials in parts by weight: 100 parts of methyl methacrylate, 0.25 parts of a compound initiator, 20 parts of a synergistic flame retardant, 6 parts of calcium stearate, 5 parts of an antioxidant DLTP, and 6 parts of N-(2-hydroxypropyl) methacrylamide; the compound initiator is prepared by compounding tert-butyl peroxy-3,5,5-trimethylhexanoate, di-tert-butyl peroxide, and azobisisobutyronitrile in a mass ratio of 1.3:1:1.2.

[0027] The preparation method of the synergistic flame retardant is as follows: pre-treated zinc-aluminum hydrotalcite is uniformly dispersed in xylene at a solid-liquid ratio of 10 g / L to prepare a dispersion; cyanoguanidine, tricresyl phosphate, and vinyltriethoxysilane are added to the dispersion at a dosage ratio of 1.2 mol / L, 1.4 mol / L, and 1.2 mol / L, respectively; after stirring and mixing at a temperature of 75°C for 50 minutes, 3% by mass of benzoyl peroxide and 2.5% by mass of 4-dimethylaminopyridine are added to the obtained mixture, and after uniform dispersion, the mixture is kept warm for reaction at a temperature of 90°C for 5 hours; after the reaction is completed, the xylene in the product is removed by vacuum distillation, and the product is then washed and dried to obtain the synergistic flame retardant.

[0028] The preparation method of the pretreated zinc-aluminum hydrotalcite is as follows: the zinc-aluminum hydrotalcite is added into a 0.12 mol / L hexadecyltrimethylammonium bromide aqueous solution at a dosage ratio of 0.1 g / mL, stirred evenly, and then stirred and reacted at a temperature of 90° C. for 3 hours; after the reaction is completed, the product components are sequentially subjected to solid-liquid separation, washing and drying treatment to obtain the pretreated zinc-aluminum hydrotalcite.

[0029] A production process for PMMA based on a nitrogen-phosphorus-silicon system with synergistic flame retardancy comprises the following steps: Step 1: Accurately weigh all the raw materials, mix and stir them evenly, and then pour them into the dipping tank. Lead the alkali-free glass fiber roving from the creel, pass through the yarn separation plate and enter the recyclable closed dipping tank equipped with a tension roller for dipping treatment; wherein, the tension roller makes the angle of the alkali-free glass fiber roving entering the preforming die be 2°; Step 2: After being soaked, the excess resin and bubbles are discharged through the preforming mold for preforming, and then enter the forming mold for gelation and curing; the cured product is continuously pulled out of the mold by the traction equipment at a pultrusion speed of 0.5m / min, and the final product is the PMMA finished product; Among them, the volume content of alkali-free glass fiber roving in PMMA is 65%; the heating temperatures of the forming mold are: the temperature of zone 1 is 110°C, the temperature of zone 2 is 120°C, and the temperature of zone 3 is 110°C.

[0030] Comparative Example: The difference from Example 1 is that an equal amount of zinc-aluminum hydrotalcite is used in this comparative example to replace the synergistic flame retardant.

[0031] Performance test: The relevant indicators of each PMMA sample produced in Examples 1 to 3 and the comparative example were tested, and the test results were recorded in the following table: Comparing and analyzing the relevant data in the table shows that the PMMA produced by the present invention not only has excellent flame retardancy but also possesses excellent mechanical properties, effectively guaranteeing its quality. This indicates that the PMMA and its production process provided by the present invention, which utilizes a nitrogen-phosphorus-silicon system for synergistic flame retardancy, have broader market prospects and are more suitable for promotion.

[0032] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0033] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to the specific embodiments described. Obviously, many modifications and variations are possible based on the content of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A PMMA based on nitrogen-phosphorus-silicon system synergistic flame retardancy, characterized in that: The invention comprises the following raw materials in parts by weight: 80 to 100 parts of methyl methacrylate, 0.1 to 0.25 parts of compound initiator, 10 to 20 parts of synergistic flame retardant, 3 to 6 parts of release agent, 2 to 5 parts of antioxidant and 2 to 6 parts of antistatic agent.

2. The PMMA based on nitrogen-phosphorus-silicon system synergistic flame retardancy according to claim 1, characterized in that: The preparation method of the synergistic flame retardant comprises the following steps: uniformly dispersing pretreated zinc-aluminum hydrotalcite in xylene at a solid-liquid ratio of 5-10 g / L to prepare a dispersion; adding cyanoguanidine, tricresyl phosphate, and vinyltriethoxysilane into the dispersion at a dosage ratio of 1-1.2 mol / L, 1.2-1.4 mol / L, and 1.1-1.2 mol / L, respectively; stirring and mixing at a temperature of 65-75° C. for 50-80 minutes; adding 2-3% by weight of an initiator and 1.5-2.5% by weight of a catalyst to the obtained mixture; uniformly dispersing the mixture; and heat-retaining the mixture at a temperature of 80-90° C. for 5-8 hours; and after the reaction is completed, removing xylene from the product by reduced pressure distillation, followed by washing and drying to obtain the synergistic flame retardant.

3. The PMMA based on nitrogen-phosphorus-silicon system synergistic flame retardancy according to claim 2, characterized in that: The preparation method of the pretreated zinc-aluminum hydrotalcite comprises the following steps: adding the zinc-aluminum hydrotalcite at a dosage ratio of 0.05 to 0.1 g / mL into a 0.08 to 0.12 mol / L aqueous solution of hexadecyltrimethylammonium bromide, stirring evenly, and then reacting at a temperature of 75 to 90° C. with stirring for 3 to 6 hours; after the reaction is completed, sequentially performing solid-liquid separation, washing, and drying treatments on the resultant components to obtain the pretreated zinc-aluminum hydrotalcite.

4. The PMMA based on nitrogen-phosphorus-silicon system synergistic flame retardancy according to claim 2, characterized in that: The initiator is selected from any one of benzoyl peroxide and lauroyl peroxide.

5. The PMMA based on nitrogen-phosphorus-silicon system synergistic flame retardancy according to claim 2, characterized in that: The catalyst is selected from any one of pyridine, triethylamine, 4-dimethylaminopyridine and N-methylimidazole.

6. The PMMA based on nitrogen-phosphorus-silicon system synergistic flame retardancy according to claim 1, characterized in that: The composite initiator is prepared by compounding tert-butyl peroxy-3,5,5-trimethylhexanoate, di-tert-butyl peroxide and azobisisobutyronitrile in a mass ratio of 1-1.3:0.8-1:1-1.

2.

7. The PMMA based on nitrogen-phosphorus-silicon system synergistic flame retardancy according to claim 1, characterized in that: The release agent is selected from any one of zinc stearate, montan wax and calcium stearate.

8. The PMMA based on nitrogen-phosphorus-silicon system synergistic flame retardancy according to claim 1, characterized in that: The antioxidant is selected from any one of antioxidant 1010, antioxidant 168, antioxidant DLTP, and antioxidant 330.

9. The PMMA based on nitrogen-phosphorus-silicon system synergistic flame retardancy according to claim 1, characterized in that: The antistatic agent is selected from any one of N-hydroxymethyl acrylamide, N-(4-hydroxyphenyl) methacrylamide, N-(2-hydroxypropyl) methacrylamide, and N-(hydroxymethyl) nicotinamide.

10. A production process for PMMA based on nitrogen-phosphorus-silicon system synergistic flame retardancy according to any one of claims 1 to 9, characterized in that: The following steps are involved: Step 1: Accurately weigh all raw materials, mix and stir them evenly, and then pour them into a dipping tank. Lead the alkali-free glass fiber roving from the creel, pass through a yarn separation plate and enter a recyclable closed dipping tank equipped with a tension roller for dipping. The tension roller ensures that the angle of the alkali-free glass fiber roving when entering the preforming die is ≤2°. Step 2: After being soaked, excess resin and bubbles are discharged through a preforming mold for preforming, and then enters a forming mold for gelation and curing; the cured product is continuously pulled out of the mold by a traction device at a pultrusion speed of 0.2 to 0.5 m / min, and the final product is a PMMA finished product; wherein the volume content of alkali-free glass fiber roving in PMMA is 55 to 65%; the heating temperatures of the forming mold are: zone 1 temperature is 90 to 110°C, zone 2 temperature is 100 to 120°C, and zone 3 temperature is 100 to 110°C.

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