A phosphorus-based flame retardant unsaturated polyester resin and a method for synthesizing the same

Abstract

The application discloses a phosphoric acid group flame-retardant unsaturated polyester resin and a synthesis method thereof, and belongs to the technical field of chemical raw material production. A phosphoric acid group flame-retardant unsaturated polyester resin monomer is obtained by mixing reaction of a hydroxyl monomer, a phosphoryl dichloride monomer, an organic solvent and triethylamine; a polyester resin is obtained by mixing reaction of the phosphoric acid group flame-retardant unsaturated polyester resin monomer, phthalic anhydride, maleic anhydride and neopentyl glycol; and the phosphoric acid group flame-retardant unsaturated polyester resin is obtained by mixing reaction of the polyester resin and polyurethane wrapped aluminum hydroxide emulsion. The phosphoric acid group flame-retardant unsaturated polyester resin monomer is obtained by chemical synthesis, and then the polyester resin is further obtained by polymerization; the polyester resin is reacted with the polyurethane wrapped aluminum hydroxide emulsion, so that the phosphoric acid group flame-retardant unsaturated polyester resin which does not contain halogen groups and has good flame-retardant performance and mechanical properties is obtained.

Description

Technical Field

[0001] This invention belongs to the field of chemical raw material production technology, specifically relating to a phosphate-based flame-retardant unsaturated polyester resin and its synthesis method. Background Technology

[0002] Unsaturated polyester resin is a thermosetting resin formed by the condensation polymerization of unsaturated diacids and diols, or saturated diacids and unsaturated diols, through esterification. Unsaturated polyester resin possesses excellent physical and chemical properties, such as abrasion resistance, heat resistance, and chemical corrosion resistance, and it does not readily react chemically with other substances. It also exhibits excellent processing performance; by adding different auxiliaries and pigments, it can be produced into products of various shapes and colors. Unsaturated polyester resin is widely used in construction engineering, automobile manufacturing, shipbuilding, and craft manufacturing, among other fields.

[0003] In existing technologies, the molecular structure and chemical composition of unsaturated polyester resins make them highly flammable, and they also produce a large amount of toxic gases and fumes during combustion. The flammability of unsaturated polyester resins has significantly hindered their further application in daily life. To expand the application range of unsaturated polyester resins, especially to meet the requirements of some special fields, it is usually necessary to perform targeted flame-retardant modification on unsaturated polyester resins while maintaining their overall performance. Existing flame-retardant modification methods for high-molecular-weight materials typically involve physical modification, i.e., mixing halogenated flame retardants into the resin matrix. For example, CN114536892A discloses an ultra-low dielectric loss high-frequency high-speed copper-clad laminate and its preparation method, in which the flame retardants used are halogenated flame retardants such as tetrabromobisphenol A and decabromodiphenyl ether.

[0004] In practice, the inclusion of halogenated flame retardants leads to the production of large amounts of toxic gases and fumes during combustion of polymer materials. With advancements in science and technology and increased environmental awareness, coupled with the enactment of numerous environmental laws and regulations, halogenated flame retardants are now on the verge of being phased out, as they do not align with the scientific principles of green chemistry. Furthermore, the inclusion of halogenated flame retardants in polymer materials can cause filler migration and aggregation during long-term use, leading not only to the inactivation of flame-retardant components and a significant reduction in the flame-retardant properties of the resin, but also to a decrease in the mechanical and curing properties of the resin system. Therefore, the development of new halogen-free flame retardants is of great significance. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention chemically synthesizes a phosphate-based flame-retardant unsaturated polyester resin monomer, which is then further polymerized to obtain a polyester resin. This polyester resin is then reacted with a polyurethane-coated aluminum hydroxide emulsion to obtain a phosphate-based flame-retardant unsaturated polyester resin that does not contain halogen groups and possesses excellent flame-retardant and mechanical properties, thereby solving the technical problems mentioned in the background art. Specifically, the technical solution of this invention includes the following:

[0006] One objective of this invention is to provide a method for synthesizing a phosphate-based flame-retardant unsaturated polyester resin, the method comprising the following steps:

[0007] Hydroxyl monomer, phosphoryl dichloro monomer, organic solvent and triethylamine are mixed in a molar ratio of 1.1~1.5:1.1~1.3:4:0.45 in a low temperature environment, and then heated to 37℃~45℃ and reacted for 2h~5h to obtain phosphoric acid-based flame-retardant unsaturated polyester resin monomer;

[0008] Phosphate-based flame-retardant unsaturated polyester resin monomer, phthalic anhydride, maleic anhydride and neopentyl glycol are mixed in a molar ratio of 4.1~5.5:2.1~2.5:1.2~1.8:2 and heated to 150℃~160℃ for 1h~3h, and then heated to 200℃~250℃ for 2h~5h to obtain polyester resin.

[0009] Polyester resin and polyurethane-coated aluminum hydroxide emulsion are mixed and heated to 100℃~120℃ for 2.5h~3h to obtain phosphate-based flame-retardant unsaturated polyester resin.

[0010] Furthermore, the hydroxyl monomer includes bisphenol A, 4,4'-dihydroxybiphenyl, or 5,5'-dihydroxy-2,2'-bipyridine.

[0011] Furthermore, the phosphoryl dichloride monomer includes phenyl phosphoryl dichloride, phenyl phosphate dichloride, or methyl phosphate dichloride.

[0012] Furthermore, the organic solvent includes tetrahydrofuran.

[0013] Furthermore, the low-temperature environment is -1℃ to 3℃.

[0014] Furthermore, the preparation method of the polyurethane-coated aluminum hydroxide emulsion includes the following steps:

[0015] Diisocyanate, polypolyol, aluminum hydroxide and dibutyltin dilaurate are mixed in a weight ratio of 13~15:40~44:21~23:0.2~0.3 and heated to 60℃~65℃ for pre-reaction for 1.5h~2h to obtain polyurethane prepolymer;

[0016] Polyurethane prepolymer and dimethylolpropionic acid are heated to 75℃~80℃ for chain extension reaction for 1h~2h, then cooled to 40℃ and triethylamine is added for 30min~40min. After that, deionized water is added and stirred at high speed to obtain polyurethane-coated aluminum hydroxide emulsion.

[0017] Furthermore, the diisocyanate includes toluene diisocyanate.

[0018] Furthermore, the polypolyol includes polypropylene glycol 400, where polypropylene glycol 400 refers to polypropylene glycol with an Mn of 400.

[0019] Furthermore, the particle size of the aluminum hydroxide is 15 μm.

[0020] Furthermore, the weight ratio of the diisocyanate: dimethylolpropionic acid: triethylamine is 1:0.5:0.4.

[0021] Furthermore, the amount of deionized water added is 5 to 6 times the total weight of the polyurethane prepolymer and dimethylolpropionic acid.

[0022] Furthermore, the conditions for high-speed stirring include a stirring speed of 1000 r / min and a stirring time of 30 min.

[0023] Furthermore, the weight ratio of the polyester resin to the polyurethane-coated aluminum hydroxide emulsion is 1:0.2~0.3.

[0024] A second objective of this invention is to provide a phosphate-based flame-retardant unsaturated polyester resin prepared by a method for synthesizing phosphate-based flame-retardant unsaturated polyester resin.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] This invention utilizes chemical synthesis to first react hydroxyl monomers and phosphoryl dichloride monomers to obtain phosphoric acid-based flame-retardant unsaturated polyester resin monomers. Under the catalysis of triethylamine, triethylamine enhances the nucleophilicity of the hydroxyl monomers through deprotonation, enabling them to attack the phosphorus atoms on the phosphoryl dichloride monomers. Simultaneously, it neutralizes the generated hydrogen chloride, thereby promoting the forward reaction and forming stable phosphoester bonds to obtain phosphoric acid-based flame-retardant unsaturated polyester resin monomers, introducing phosphorus-containing flame-retardant groups. Then, the phosphoric acid-based flame-retardant unsaturated polyester resin monomers are polymerized and chain-extended with phthalic anhydride, maleic anhydride, and neopentyl glycol to prepare a polyester resin containing phosphorus-containing flame-retardant groups. Next, aluminum hydroxide, an inorganic compound with flame-retardant properties, was encapsulated into the polyurethane via in-situ polymerization. Through the condensation reaction between the polyurethane and the polyester resin, the interfacial bonding between aluminum hydroxide and the polyester resin was enhanced, reducing the defect that aluminum hydroxide easily agglomerates, which can lead to a decrease in the mechanical and flame-retardant properties of the resin. The synergistic effect of the phosphoric acid flame-retardant unsaturated polyester resin monomer containing phosphorus flame-retardant groups and aluminum hydroxide resulted in a phosphoric acid flame-retardant unsaturated polyester resin with good flame-retardant properties. At the same time, the polymerization encapsulation modification of aluminum hydroxide also improved the mechanical properties of the phosphoric acid flame-retardant unsaturated polyester resin. Attached Figure Description

[0027] Figure 1 The 1H NMR spectrum of the phosphate-based flame-retardant unsaturated polyester resin prepared in Example 3 of this invention.

[0028] Figure 2 The image shows the 13C NMR spectrum of the phosphate-based flame-retardant unsaturated polyester resin prepared in Example 3 of this invention. Detailed Implementation

[0029] The technical solution of the present invention will be clearly and completely described below through embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Unless otherwise stated, all raw materials and reagents used in this invention are commercially available or can be prepared by known methods.

[0031] Preparation Example 1:

[0032] The preparation method of polyurethane-coated aluminum hydroxide emulsion includes the following steps:

[0033] Weigh out 13 parts by weight 40 parts by weight of polypropylene glycol 400, 21 parts by weight of aluminum hydroxide (particle size 15 μm), and 0.2 parts by weight of dibutyltin dilaurate were added to a reactor and then mixed and dispersed uniformly using an ultrasonic power of 200 W. The reactor was then heated to 60 °C for pre-reaction for 1.5 h. Next, 6.5 parts by weight of dimethylolpropionic acid were added to the polyurethane prepolymer obtained after the reaction, and the mixture was stirred and heated to 75 °C for chain extension reaction for 1 h. After the reaction, the reactor temperature was lowered to 40 °C, and 5.2 parts by weight of triethylamine were added as a salt-forming agent for reaction for 30 min. After the reaction, five times the total weight of the polyurethane prepolymer and dimethylolpropionic acid in deionized water was added, and the mixture was emulsified at a high stirring speed of 1000 r / min for 30 min to obtain a polyurethane-coated aluminum hydroxide emulsion.

[0034] Preparation Example 2:

[0035] The preparation method of polyurethane-coated aluminum hydroxide emulsion includes the following steps:

[0036] Weigh out 14 parts by weight 42 parts by weight of polypropylene glycol 400, 22 parts by weight of aluminum hydroxide (particle size 15 μm), and 0.25 parts by weight of dibutyltin dilaurate were added to a reactor and then mixed and dispersed uniformly using an ultrasonic power of 200 W. The reactor was then heated to 60 °C for pre-reaction for 2 h. Next, 7 parts by weight of dimethylolpropionic acid were added to the polyurethane prepolymer obtained after the reaction, and the mixture was stirred and heated to 75 °C for chain extension reaction for 1.5 h. After the reaction, the reactor temperature was lowered to 40 °C, and 5.6 parts by weight of triethylamine were added as a salt-forming agent for reaction for 35 min. After the reaction, 5.5 times the total weight of the polyurethane prepolymer and dimethylolpropionic acid in deionized water was added, and the mixture was emulsified at a high stirring speed of 1000 r / min for 30 min to obtain a polyurethane-coated aluminum hydroxide emulsion.

[0037] Preparation Example 3:

[0038] The preparation method of polyurethane-coated aluminum hydroxide emulsion includes the following steps:

[0039] Weigh out 15 portions by weight 44 parts by weight of polypropylene glycol 400, 23 parts by weight of aluminum hydroxide (particle size 15 μm), and 0.3 parts by weight of dibutyltin dilaurate were added to a reactor and then mixed and dispersed uniformly using an ultrasonic power of 200 W. The reactor was then heated to 65 °C for pre-reaction for 2 h. Next, 7.5 parts by weight of dimethylolpropionic acid were added to the polyurethane prepolymer obtained after the reaction, and the mixture was stirred and heated to 80 °C for chain extension reaction for 2 h. After the reaction, the reactor temperature was lowered to 40 °C, and 6 parts by weight of triethylamine were added as a salt-forming agent for reaction for 40 min. After the reaction, deionized water at a total weight of 6 times that of the polyurethane prepolymer and dimethylolpropionic acid was added, and the mixture was emulsified at a high stirring speed of 1000 r / min for 30 min to obtain a polyurethane-coated aluminum hydroxide emulsion.

[0040] Preparation Example 4:

[0041] The preparation method of polyurethane-coated aluminum hydroxide emulsion includes the following steps:

[0042] In Preparation Example 3, aluminum hydroxide was replaced with aluminum hydroxide with a particle size of 35 μm, and the rest of the preparation process was the same as in Preparation Example 3.

[0043] Preparation Example 5:

[0044] The preparation method of polyurethane-coated aluminum hydroxide emulsion includes the following steps:

[0045] In Preparation Example 3, polypropylene glycol 400 was replaced with polypropylene glycol 2000, and the rest of the preparation process remained the same as in Preparation Example 3.

[0046] Example 1:

[0047] A method for synthesizing a phosphate-based flame-retardant unsaturated polyester resin specifically includes the following steps:

[0048] The reactor was cooled to -1℃, and then nitrogen gas was introduced to purge the air inside the reactor. Using nitrogen as a protective gas, 1.1 mol of bisphenol A, 4 mol of tetrahydrofuran, and 0.45 mol of triethylamine were weighed and added to the reactor and mixed. When the temperature of the mixture stabilized at -1℃, 1.1 mol of phenylphosphodichlorophosphate was added and mixed. After the addition was complete, the reactor was heated to 37℃ and reacted for 2 hours. After the reaction was completed, the crude product of phosphoric acid flame retardant unsaturated polyester resin monomer was obtained. The crude product of phosphoric acid flame retardant unsaturated polyester resin monomer was then filtered to remove triethylamine. After drying, washing, and secondary drying, the phosphoric acid flame retardant unsaturated polyester resin monomer was obtained.

[0049] 4.1 mol of phosphate-based flame-retardant unsaturated polyester resin monomer, 2.1 mol of phthalic anhydride, 1.2 mol of maleic anhydride and 2 mol of neopentyl glycol were weighed and added to a reaction vessel and mixed. The reaction vessel was initially heated to 150°C at a heating rate of 5°C / min and kept at that temperature for 1 hour. After the reaction was completed, the temperature was increased again at a heating rate of 10°C / min to 200°C. The heating power was kept constant to maintain a stable temperature. During the heating process, the temperature of the distillation outlet of the reaction vessel was kept below 100°C. The reaction was carried out for 2 hours to obtain polyester resin.

[0050] Weigh 1 part by weight of polyester resin and 0.2 parts by weight of polyurethane-coated aluminum hydroxide emulsion obtained in Preparation Example 1, mix and heat to 100°C for 2.5 h to obtain phosphate-based flame-retardant unsaturated polyester resin. The acid value of the phosphate-based flame-retardant unsaturated polyester resin was measured to be 49.2 mg / g. Add 0.3 times the weight of phosphate-based flame-retardant unsaturated polyester resin and styrene to mix and store.

[0051] Example 2:

[0052] A method for synthesizing a phosphate-based flame-retardant unsaturated polyester resin specifically includes the following steps:

[0053] The reactor was cooled to 0°C, and then nitrogen gas was introduced to purge the air from the reactor. Using nitrogen as a protective gas, 1.3 mol of 4,4'-dihydroxybiphenyl, 4 mol of tetrahydrofuran, and 0.45 mol of triethylamine were weighed and added to the reactor for mixing. When the temperature of the mixture stabilized at 0°C, 1.2 mol of phenyl dichloride phosphate was added and mixed. After the addition was complete, the reactor was heated to 40°C and reacted for 4 hours. After the reaction was completed, the crude product of phosphoric acid-based flame-retardant unsaturated polyester resin monomer was obtained. The crude product of phosphoric acid-based flame-retardant unsaturated polyester resin monomer was then filtered to remove triethylamine. After drying, washing, and secondary drying, the phosphoric acid-based flame-retardant unsaturated polyester resin monomer was obtained.

[0054] 4.8 mol of phosphate-based flame-retardant unsaturated polyester resin monomer, 2.3 mol of phthalic anhydride, 1.5 mol of maleic anhydride and 2 mol of neopentyl glycol were weighed and added to a reaction vessel and mixed. The reaction vessel was initially heated to 155°C at a heating rate of 5°C / min and kept at that temperature for 2 hours. After the reaction was completed, the temperature was increased again at a heating rate of 10°C / min to 230°C. The heating power was kept constant to maintain a stable temperature. During the heating process, the temperature of the distillation outlet of the reaction vessel was kept below 100°C. The reaction was carried out for 4 hours to obtain polyester resin.

[0055] Weigh 1 part by weight of polyester resin and 0.25 parts by weight of polyurethane-coated aluminum hydroxide emulsion obtained in Preparation Example 2, mix and heat to 110°C for 3 hours to obtain phosphate-based flame-retardant unsaturated polyester resin. The acid value of the phosphate-based flame-retardant unsaturated polyester resin was measured to be 48.7 mg / g. Add 0.3 times the weight of phosphate-based flame-retardant unsaturated polyester resin and styrene to mix and store.

[0056] Example 3:

[0057] A method for synthesizing a phosphate-based flame-retardant unsaturated polyester resin specifically includes the following steps:

[0058] The reaction vessel was cooled to 3°C, and then nitrogen gas was introduced to purge the air inside the vessel. Using nitrogen as a protective gas, 1.5 mol of 5,5'-dihydroxy-2,2'-bipyridine, 4 mol of tetrahydrofuran, and 0.45 mol of triethylamine were weighed and added to the reaction vessel for mixing. When the temperature of the mixture stabilized at 3°C, 1.3 mol of methyl dichlorophosphate was added and mixed. After the addition was complete, the reaction vessel was heated to 45°C and reacted for 5 hours. After the reaction was completed, the crude product of phosphoric acid-based flame-retardant unsaturated polyester resin monomer was obtained. The crude product of phosphoric acid-based flame-retardant unsaturated polyester resin monomer was then filtered to remove triethylamine. After drying, washing, and secondary drying, the phosphoric acid-based flame-retardant unsaturated polyester resin monomer was obtained.

[0059] 5.5 mol of phosphate-based flame-retardant unsaturated polyester resin monomer, 2.5 mol of phthalic anhydride, 1.8 mol of maleic anhydride and 2 mol of neopentyl glycol were weighed and added to a reaction vessel and mixed. The reaction vessel was initially heated to 160°C at a heating rate of 8°C / min and held at that temperature for 3 hours. After the reaction was completed, the temperature was raised to 250°C at a heating rate of 15°C / min and then kept constant to maintain a stable temperature. During the heating process, the temperature of the distillation outlet of the reaction vessel was kept below 100°C. The reaction was carried out for 5 hours to obtain polyester resin.

[0060] Weigh 1 part by weight of polyester resin and 0.3 parts by weight of polyurethane-coated aluminum hydroxide emulsion obtained in Preparation Example 3, mix and heat to 120°C for 3 hours to obtain phosphate-based flame-retardant unsaturated polyester resin. The acid value of the phosphate-based flame-retardant unsaturated polyester resin was measured to be 49.6 mg / g. Add 0.3 times the weight of phosphate-based flame-retardant unsaturated polyester resin and styrene to mix and store.

[0061] Comparative Example 1:

[0062] A method for synthesizing a phosphate-based flame-retardant unsaturated polyester resin specifically includes the following steps:

[0063] The polyurethane-coated aluminum hydroxide emulsion in Example 3 was replaced with the polyurethane-coated aluminum hydroxide emulsion obtained in Preparation Example 4. The rest of the preparation process was the same as in Example 3. The acid value of the phosphate-based flame-retardant unsaturated polyester resin was measured to be 79.2 mg / g. Styrene was added in 0.3 times the weight of the phosphate-based flame-retardant unsaturated polyester resin and stored.

[0064] Comparative Example 2:

[0065] A method for synthesizing a phosphate-based flame-retardant unsaturated polyester resin specifically includes the following steps:

[0066] The polyurethane-coated aluminum hydroxide emulsion in Example 3 was replaced with the polyurethane-coated aluminum hydroxide emulsion obtained in Preparation Example 5. The rest of the preparation process was the same as in Example 3. The acid value of the phosphate-based flame-retardant unsaturated polyester resin was measured to be 73.7 mg / g. Styrene was added in 0.3 times the weight of the phosphate-based flame-retardant unsaturated polyester resin and stored.

[0067] Comparative Example 3:

[0068] A method for synthesizing a phosphate-based flame-retardant unsaturated polyester resin specifically includes the following steps:

[0069] The reaction vessel was cooled to 3°C, and then nitrogen gas was introduced to purge the air inside the vessel. Using nitrogen as a protective gas, 1.5 mol of 5,5'-dihydroxy-2,2'-bipyridine, 4 mol of tetrahydrofuran, and 0.45 mol of triethylamine were weighed and added to the reaction vessel for mixing. When the temperature of the mixture stabilized at 3°C, 1.3 mol of methyl dichlorophosphate was added and mixed. After the addition was complete, the reaction vessel was heated to 45°C and reacted for 5 hours. After the reaction was completed, the crude product of phosphoric acid-based flame-retardant unsaturated polyester resin monomer was obtained. The crude product of phosphoric acid-based flame-retardant unsaturated polyester resin monomer was then filtered to remove triethylamine. After drying, washing, and secondary drying, the phosphoric acid-based flame-retardant unsaturated polyester resin monomer was obtained.

[0070] 5.5 mol of phosphate-based flame-retardant unsaturated polyester resin monomer, 2.5 mol of phthalic anhydride, 1.8 mol of maleic anhydride, and 2 mol of neopentyl glycol were weighed and added to a reaction vessel and mixed. The reaction vessel was initially heated to 160°C at a heating rate of 8°C / min and held at that temperature for 3 hours. After the reaction was completed, the temperature was raised a second time at a heating rate of 15°C / min to 250°C. The heating power was kept constant to maintain a stable temperature. During the heating process, the temperature at the distillation outlet of the reaction vessel was kept below 100°C. The reaction was carried out for 5 hours to obtain phosphate-based flame-retardant unsaturated polyester resin. The acid value of the phosphate-based flame-retardant unsaturated polyester resin was measured to be 89.6 mg / g. Styrene was added in 0.3 times the weight of the phosphate-based flame-retardant unsaturated polyester resin and stored.

[0071] Comparative Example 4:

[0072] A method for synthesizing a phosphate-based flame-retardant unsaturated polyester resin specifically includes the following steps:

[0073] The polyurethane-coated aluminum hydroxide emulsion in Example 3 was replaced with aluminum hydroxide (particle size of 15 μm), and the rest of the preparation process was the same as in Example 3. The acid value of the phosphate-based flame-retardant unsaturated polyester resin was measured to be 81.2 mg / g. Styrene was added in 0.3 times the weight of the phosphate-based flame-retardant unsaturated polyester resin and stored.

[0074] The limiting oxygen index (GB / T 2406.2-2009 Determination of burning behavior by oxygen index method for plastics - Part 2: Room temperature test), UL94 flame retardancy rating (UL94 flame retardancy test method and standard), UL-94 flame retardancy rating after irradiation with 365nm ultraviolet light at 50°C (irradiation time of 24h, 72h and 120h), tensile strength and elongation at break of the phosphate-based flame-retardant unsaturated polyester resins obtained in Examples 1-3 and Comparative Examples 1-4 were tested. The results are shown in Table 1 below.

[0075] Table 1 Performance Test Results

[0076] Test Project Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Limiting oxygen index (%) 48.7 48.5 49.1 18.7 33.4 31.3 21.4 UL-94 flame retardant rating V-0 V-0 V-0 V-2 V-1 V-1 V-1 UL-94 flame retardant rating (after 24 hours of UV exposure) V-0 V-0 V-0 V-2 V-1 V-1 V-1 UL-94 flame retardant rating (72 hours of UV exposure) V-0 V-0 V-0 V-2 V-2 V-1 V-1 UL-94 flame retardant rating (120h UV irradiation) V-0 V-0 V-0 V-2 V-2 V-2 V-2 Tensile strength (MPa) 50.3 49.6 49.4 9.7 31.8 29.5 15.2 Elongation at break (%) 188 185 189 56.3 97.1 94.8 76.7

[0077] From Table 1 above, we can see that:

[0078] This invention achieves excellent flame-retardant properties in the obtained phosphate-based flame-retardant unsaturated polyester resin by synergistically combining a phosphoric acid flame-retardant group-containing phosphate-based unsaturated polyester resin monomer with modified aluminum hydroxide. At the same time, the polymerization and encapsulation modification of aluminum hydroxide also improves the mechanical properties of the phosphate-based flame-retardant unsaturated polyester resin.

[0079] The embodiments described above provide a detailed explanation of the technical solutions and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Various changes and modifications can be made to the present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed.

Claims

1. A method for the synthesis of a phosphorus acid-based flame-retardant unsaturated polyester resin, characterized in that, The synthesis method includes the following steps: Hydroxyl monomer, phosphoryl dichloro monomer, organic solvent and triethylamine are mixed in a molar ratio of 1.1~1.5:1.1~1.3:4:0.45 in a low temperature environment, and then heated to 37℃~45℃ and reacted for 2h~5h to obtain phosphoric acid-based flame-retardant unsaturated polyester resin monomer; Phosphate-based flame-retardant unsaturated polyester resin monomer, phthalic anhydride, maleic anhydride and neopentyl glycol are mixed in a molar ratio of 4.1~5.5:2.1~2.5:1.2~1.8:2 and heated to 150℃~160℃ for 1h~3h, and then heated to 200℃~250℃ for 2h~5h to obtain polyester resin. Polyester resin and polyurethane-coated aluminum hydroxide emulsion are mixed and heated to 100℃~120℃ for 2.5h~3h to obtain phosphate-based flame-retardant unsaturated polyester resin. The preparation method of the polyurethane-coated aluminum hydroxide emulsion includes the following steps: Diisocyanate, polypolyol, aluminum hydroxide and dibutyltin dilaurate are mixed in a weight ratio of 13~15:40~44:21~23:0.2~0.3 and heated to 60℃~65℃ for pre-reaction for 1.5h~2h to obtain polyurethane prepolymer; Polyurethane prepolymer and dimethylolpropionic acid were heated to 75℃~80℃ for chain extension reaction for 1h~2h, then cooled to 40℃ and triethylamine was added for 30min~40min. Deionized water was then added and stirred at high speed to obtain polyurethane-coated aluminum hydroxide emulsion. The aluminum hydroxide has a particle size of 15 μm; The polyol is polypropylene glycol 400.

2. The process for the synthesis of phosphorus-based flame retardant unsaturated polyester resin according to claim 1, characterized in that, The hydroxy monomer includes bisphenol A, 4,4'-dihydroxybiphenyl, or 5,5'-dihydroxy-2,2'-bipyridine.

3. The method for synthesizing a phosphate-based flame-retardant unsaturated polyester resin according to claim 1, characterized in that, The phosphoryl dichloride monomers include phenylphosphodichloride, phenyl phosphate dichloride, or methyl phosphate dichloride.

4. The method for synthesizing a phosphate-based flame-retardant unsaturated polyester resin according to claim 1, characterized in that, The diisocyanate includes toluene diisocyanate.

5. The method for synthesizing a phosphate-based flame-retardant unsaturated polyester resin according to claim 1, characterized in that, The weight ratio of the diisocyanate: dimethylolpropionic acid: triethylamine is 1:0.5:0.

4.

6. The method for synthesizing a phosphate-based flame-retardant unsaturated polyester resin according to claim 1, characterized in that, The amount of deionized water added is 5 to 6 times the total weight of the polyurethane prepolymer and dimethylolpropionic acid.

7. The method for synthesizing a phosphate-based flame-retardant unsaturated polyester resin according to claim 1, characterized in that, The weight ratio of the polyester resin to the polyurethane-coated aluminum hydroxide emulsion is 1:0.2~0.

3.

8. A phosphate-based flame-retardant unsaturated polyester resin prepared by the synthesis method of the phosphate-based flame-retardant unsaturated polyester resin according to any one of claims 1 to 7.

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