Phosphate-based flame-retardant unsaturated polyester resin and synthesis method thereof

Abstract

The invention discloses phosphate-based flame-retardant unsaturated polyester resin and a synthesis method thereof, and belongs to the technical field of chemical raw material production. The preparation method comprises the following steps: mixing a hydroxyl monomer, a phosphoryl dichloride monomer, an organic solvent and triethylamine, and reacting to obtain a phosphate flame-retardant unsaturated polyester resin monomer; mixing and reacting the phosphate flame-retardant unsaturated polyester resin monomer, phthalic anhydride, maleic anhydride and neopentyl glycol to obtain polyester resin; the polyester resin and the polyurethane-coated aluminum hydroxide emulsion are mixed and react to obtain the phosphate-based flame-retardant unsaturated polyester resin. According to the preparation method, a phosphate-based flame-retardant unsaturated polyester resin monomer is obtained through chemical synthesis, polyester resin is obtained through further polymerization, the polyester resin reacts with polyurethane-coated aluminum hydroxide emulsion, and the phosphate-based flame-retardant unsaturated polyester resin which does not contain halogen groups and has good flame retardant property and mechanical property is obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical raw material production, and particularly relates to a phosphoric acid-based flame-retardant unsaturated polyester resin and a synthesis method thereof. Background Art

[0002] Unsaturated polyester resin is a thermosetting resin formed by the esterification and polycondensation of unsaturated dibasic acids and diols, or saturated dibasic acids and unsaturated diols. Unsaturated polyester resin possesses excellent physical and chemical properties, such as wear resistance, heat resistance, and chemical corrosion resistance, and is not susceptible to chemical reactions with other substances. It also exhibits excellent processability and can be manufactured into products of various shapes and colors by adding various auxiliary materials and pigments. Unsaturated polyester resin is widely used in construction, automotive manufacturing, shipbuilding, and process manufacturing.

[0003] In the prior art, due to the molecular structure and chemical composition of unsaturated polyester resins, they are extremely flammable and produce large amounts of toxic gases and smoke during the combustion process. The flammability of unsaturated polyester resins has significantly hindered their further application in daily life. In order to expand the scope of application of unsaturated polyester resins, especially to meet the requirements of some special fields, it is usually necessary to carry out targeted flame retardant modification on unsaturated polyester resins while maintaining the comprehensive application performance of unsaturated polyester resins. Existing flame retardant modification methods for high-density materials are usually physical modification, that is, mixing halogen flame retardants into the resin matrix. For example, CN114536892A discloses an ultra-low dielectric loss high-frequency and high-speed copper-clad laminate and its preparation method. The flame retardants used in this invention are halogen-containing flame retardants such as tetrabromobisphenol A and decabromodiphenyl ether.

[0004] In actual implementation, the incorporation of halogen flame retardants causes polymer materials to produce large amounts of toxic gases and smoke during combustion. With the advancement of science and technology, increased awareness of environmental protection, and the promulgation of numerous environmental laws and regulations, halogen flame retardants are now on the verge of being eliminated, as they are not in line with the scientific concept of green chemistry. Furthermore, after halogen flame retardants are incorporated into polymer materials, filler migration and aggregation may occur during long-term use, causing not only the ineffectiveness of the flame retardant component and a significant reduction in the flame retardant properties of the resin, but also 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] In response to the shortcomings of the prior art, the present invention obtains a phosphoric acid-based flame-retardant unsaturated polyester resin monomer through chemical synthesis, which is then further polymerized to obtain a polyester resin. The polyester resin is then reacted with a polyurethane-coated aluminum hydroxide emulsion to obtain a phosphoric acid-based flame-retardant unsaturated polyester resin that is free of halogen groups and has excellent flame retardancy and mechanical properties, thereby solving the technical problems raised in the background art. Specifically, the technical solution of the present invention includes the following:

[0006] One of the purposes of the present invention is to provide a method for synthesizing a phosphoric acid-based flame-retardant unsaturated polyester resin, the method comprising the following steps:

[0007] A hydroxyl monomer, a phosphorus dichloride monomer, an 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 the mixture is heated to 37° C.-45° C. and reacted for 2 h-5 h to obtain a phosphoric acid-based flame-retardant unsaturated polyester resin monomer;

[0008] A phosphoric acid-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, heated to 150-160° C. for reaction for 1-3 hours, and then heated to 200-250° C. for reaction for 2-5 hours to obtain a polyester resin;

[0009] The polyester resin and the polyurethane-coated aluminum hydroxide emulsion are mixed and heated to 100° C. to 120° C. and reacted for 2.5 h to 3 h to obtain a phosphoric acid-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 phosphorus oxychloride monomer includes phenyl phosphorus oxychloride, phenyl dichlorophosphate or methyl dichlorophosphate.

[0012] Furthermore, the organic solvent includes tetrahydrofuran.

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

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

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

[0016] The polyurethane prepolymer and dimethylol propionic acid are heated to 75°C~80°C for chain extension reaction for 1h~2h, then cooled to 40°C and triethylamine is added for reaction for 30min~40min, and then 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 polyol 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 high-speed stirring conditions 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-wrapped aluminum hydroxide emulsion is 1:0.2-0.3.

[0024] A second object of the present invention is to provide a phosphoric acid-based flame retardant unsaturated polyester resin prepared by a method for synthesizing a phosphoric acid-based flame retardant unsaturated polyester resin.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The invention adopts a chemical synthesis method, wherein a hydroxyl monomer and a phosphorus oxychloride monomer are first reacted to obtain a phosphoric acid-based flame-retardant unsaturated polyester resin monomer. Under the catalysis of triethylamine, the triethylamine can enhance the nucleophilicity of the hydroxyl monomer through a deprotonation effect, so that the hydroxyl monomer attacks the phosphorus atom on the phosphorus oxychloride monomer. On the other hand, the triethylamine can neutralize the generated hydrogen chloride, thereby promoting the forward reaction to form a stable phosphoester bond to obtain the phosphoric acid-based flame-retardant unsaturated polyester resin monomer, introduce a phosphorus-containing flame-retardant group, and then polymerize the phosphoric acid-based flame-retardant unsaturated polyester resin monomer with phthalic anhydride, maleic anhydride and neopentyl glycol to extend the chain, thereby preparing a polyester resin containing the phosphorus-containing flame-retardant group. Then, aluminum hydroxide, an inorganic compound with flame retardant properties, is wrapped into the polyurethane through in-situ polymerization and wrapping. Through the condensation reaction between the polyurethane and the polyester resin, the interface bonding between the aluminum hydroxide and the polyester resin is enhanced, and the defect that aluminum hydroxide is easy to agglomerate and easily leads to a decrease in the mechanical properties and flame retardant properties of the resin is reduced. The synergistic combination of the phosphoric acid-based flame retardant unsaturated polyester resin monomer containing phosphorus flame retardant groups and aluminum hydroxide makes the obtained phosphoric acid-based flame retardant unsaturated polyester resin have good flame retardant properties. At the same time, the polymerization and wrapping modification of aluminum hydroxide also improves the mechanical properties of the phosphoric acid-based flame retardant unsaturated polyester resin. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 1H NMR spectrum of the phosphoric acid-based flame-retardant unsaturated polyester resin prepared in Example 3 of the present invention

[0028] Figure 2 This is the 13C NMR spectrum of the phosphoric acid-based flame-retardant unsaturated polyester resin prepared in Example 3 of the present invention. DETAILED DESCRIPTION

[0029] The following will clearly and completely describe the technical solutions of the present invention through 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 those skilled in the art without making any creative efforts shall fall within the scope of protection of the present invention.

[0030] Unless otherwise specified, the raw materials and reagents used in the present 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 comprises the following steps:

[0033] Weigh 13 parts by weight 40 parts by weight of polypropylene glycol 400, 21 parts by weight of aluminum hydroxide (15 μm particle size), and 0.2 parts by weight of dibutyltin dilaurate were added to a reactor. Ultrasonic mixing and dispersion were then achieved at 200 W, and the reactor was heated to 60°C for a pre-reaction of 1.5 hours. 6.5 parts by weight of dimethylolpropionic acid were then added to the resulting polyurethane prepolymer, stirred, and the mixture was heated to 75°C for a chain extension reaction of 1 hour. After the reaction, the reactor temperature was lowered to 40°C, and 5.2 parts by weight of triethylamine was added as a salt-forming agent, and the reaction was continued for 30 minutes. After the reaction, deionized water (5 times the total weight 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 minutes to produce a polyurethane-coated aluminum hydroxide emulsion.

[0034] Preparation Example 2:

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

[0036] Weigh 14 parts by weight 42 parts by weight of polypropylene glycol 400, 22 parts by weight of aluminum hydroxide (15 μm particle size), and 0.25 parts by weight of dibutyltin dilaurate were added to a reactor. Ultrasonic mixing and dispersion were then achieved at 200 W, and the reactor was heated to 60°C for a pre-reaction of 2 hours. The resulting polyurethane prepolymer was then added with 7 parts by weight of dimethylolpropionic acid, stirred, and heated to 75°C for a chain extension reaction of 1.5 hours. After the reaction, the reactor temperature was lowered to 40°C, and 5.6 parts by weight of triethylamine was added as a salt-forming agent, and the reaction was continued for 35 minutes. After the reaction, deionized water (5.5 times the total weight 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 minutes to produce a polyurethane-coated aluminum hydroxide emulsion.

[0037] Preparation Example 3:

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

[0039] Weigh 15 parts by weight 44 parts by weight of polypropylene glycol 400, 23 parts by weight of aluminum hydroxide (15 μm particle size), and 0.3 parts by weight of dibutyltin dilaurate were added to a reactor. Ultrasonic mixing and dispersion were then achieved at 200 W, and the reactor was heated to 65°C for a pre-reaction for 2 hours. 7.5 parts by weight of dimethylolpropionic acid were then added to the resulting polyurethane prepolymer, stirred, and the mixture was heated to 80°C for a chain extension reaction for 2 hours. After the reaction, the reactor temperature was lowered to 40°C, and 6 parts by weight of triethylamine was added as a salt-forming agent, and the reaction was continued for 40 minutes. After the reaction, deionized water (6 times the total weight 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 minutes to produce a polyurethane-coated aluminum hydroxide emulsion.

[0040] Preparation Example 4:

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

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

[0043] Preparation Example 5:

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

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

[0046] Example 1:

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

[0048] The reactor was cooled to -1°C, and then nitrogen was introduced to expel the air in the reactor. With 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 after mixing stabilized to -1°C, 1.1 mol of phenylphosphoryl dichloride was added and mixed. After the addition was completed, the reactor was heated to 37°C and reacted for 2 hours. After the reaction was completed, a crude phosphate-based flame-retardant unsaturated polyester resin monomer was obtained. The crude phosphate-based flame-retardant unsaturated polyester resin monomer was then filtered to remove triethylamine, and then dried, washed, and dried again to obtain a phosphate-based flame-retardant unsaturated polyester resin monomer.

[0049] 4.1 mol of a phosphoric acid-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 reactor and mixed. The reactor was heated to 150° C. at a heating rate of 5° C. / min using an electric heating jacket and kept warm for 1 hour. After the reaction was completed, the temperature was increased again at a heating rate of 10° C. / min. After the temperature reached 200° C., the heating power was kept constant to maintain a stable temperature. During the heating process, the temperature at the distillation outlet of the reactor was kept below 100° C. The reaction was continued for 2 hours to obtain a polyester resin.

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

[0051] Example 2:

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

[0053] The reactor was cooled to 0°C, and then nitrogen was introduced to expel the air in the reactor. With 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 and mixed. When the temperature after mixing stabilized to 0°C, 1.2 mol of phenyl dichloride phosphate was added and mixed. After the addition was completed, the reactor was heated to 40°C and reacted for 4 hours. After the reaction was completed, a crude phosphate-based flame-retardant unsaturated polyester resin monomer was obtained. The crude phosphate-based flame-retardant unsaturated polyester resin monomer was then filtered to remove triethylamine, and then dried, washed, and dried again to obtain a phosphate-based flame-retardant unsaturated polyester resin monomer.

[0054] 4.8 mol of a phosphoric acid-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 reactor and mixed. The reactor was heated to 155° C. at a heating rate of 5° C. / min using an electric heating jacket and kept warm for 2 hours. After the reaction was completed, the temperature was increased again at a heating rate of 10° C. / min. After the temperature reached 230° C., the heating power was kept constant to maintain a stable temperature. During the heating process, the temperature at the distillation outlet of the reactor was kept below 100° C. The reaction was continued for 4 hours to obtain a polyester resin.

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

[0056] Example 3:

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

[0058] The reactor was cooled to 3°C, and then nitrogen was introduced to expel the air in the reactor. With 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 reactor and mixed. When the temperature after mixing stabilized to 3°C, 1.3 mol of methyl dichlorophosphate was added and mixed. After the addition was completed, the reactor was heated to 45°C and reacted for 5 hours. After the reaction was completed, a crude phosphate-based flame-retardant unsaturated polyester resin monomer was obtained. The crude phosphate-based flame-retardant unsaturated polyester resin monomer was then filtered to remove triethylamine, and then dried, washed, and dried again to obtain a phosphate-based flame-retardant unsaturated polyester resin monomer.

[0059] 5.5 mol of a phosphoric acid-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 reactor and mixed. The reactor was heated to 160° C. at a heating rate of 8° C. / min using an electric heating jacket and kept heated for 3 hours. After the reaction was completed, the temperature was increased again at a heating rate of 15° C. / min. After the temperature reached 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 reactor was kept below 100° C. The reaction was continued for 5 hours to obtain a polyester resin.

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

[0061] Comparative Example 1:

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

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

[0064] Comparative Example 2:

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

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

[0067] Comparative Example 3:

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

[0069] The reactor was cooled to 3°C, and then nitrogen was introduced to expel the air in the reactor. With 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 reactor and mixed. When the temperature after mixing stabilized to 3°C, 1.3 mol of methyl dichlorophosphate was added and mixed. After the addition was completed, the reactor was heated to 45°C and reacted for 5 hours. After the reaction was completed, a crude phosphate-based flame-retardant unsaturated polyester resin monomer was obtained. The crude phosphate-based flame-retardant unsaturated polyester resin monomer was then filtered to remove triethylamine, and then dried, washed, and dried again to obtain a phosphate-based flame-retardant unsaturated polyester resin monomer.

[0070] 5.5 mol of phosphoric acid-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 into a reactor and mixed. The reactor was initially heated to 160°C at a heating rate of 8°C / min by an electric heating jacket and kept warm for reaction for 3 hours. After the reaction was completed, the temperature was increased for a second time at a heating rate of 15°C / min. After the temperature was increased to 250°C, the heating power was kept unchanged and the temperature was kept stable. During the heating process, the temperature at the distillation outlet of the reactor was kept below 100°C. The reaction was carried out for 5 hours to obtain a phosphoric acid-based flame-retardant unsaturated polyester resin. The acid value of the phosphoric acid-based flame-retardant unsaturated polyester resin was measured to be 89.6 mg / g. Styrene 0.3 times the weight of the phosphoric acid-based flame-retardant unsaturated polyester resin was added and mixed for storage.

[0071] Comparative Example 4:

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

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

[0074] The phosphate-based flame-retardant unsaturated polyester resins obtained in Examples 1 to 3 and Comparative Examples 1 to 4 were tested for limiting oxygen index (GB / T 2406.2-2009 Plastics - Determination of Combustion Behavior by Oxygen Index Method - Part 2: Room Temperature Test), UL94 flame retardancy rating (UL94 Flame Retardancy Test Method and Standard), UL-94 flame retardancy after irradiation with 365 nm ultraviolet light at a temperature of 50°C (irradiation durations of 24 h, 72 h, and 120 h), tensile strength, and elongation at break. The results are shown in Table 1 below.

[0075] Table 1 Performance test results

[0076] Test items 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 grade (UV irradiation for 24 hours) V-0 V-0 V-0 V-2 V-1 V-1 V-1 UL-94 flame retardant grade (UV irradiation 72h) V-0 V-0 V-0 V-2 V-2 V-1 V-1 UL-94 flame retardant grade (UV irradiation for 120 hours) 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 find that:

[0078] The present invention synthesizes a phosphoric acid-based flame-retardant unsaturated polyester resin monomer containing a phosphorus flame-retardant group and synergistically cooperates with modified aluminum hydroxide to obtain a phosphoric acid-based flame-retardant unsaturated polyester resin having good flame retardant properties. At the same time, the polymerization and encapsulation modification of the aluminum hydroxide also improves the mechanical properties of the phosphoric acid-based flame-retardant unsaturated polyester resin.

[0079] The embodiments described above provide a detailed description 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 may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and modifications fall within the scope of the present invention as claimed.

Claims

1. A method for synthesizing a phosphoric acid-based flame-retardant unsaturated polyester resin, characterized in that: The synthesis method comprises the following steps: A hydroxyl monomer, a phosphorus dichloride monomer, an 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 the mixture is heated to 37° C.-45° C. and reacted for 2 h-5 h to obtain a phosphoric acid-based flame-retardant unsaturated polyester resin monomer; A phosphoric acid-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, heated to 150-160° C. for reaction for 1-3 hours, and then heated to 200-250° C. for reaction for 2-5 hours to obtain a polyester resin; The polyester resin and the polyurethane-coated aluminum hydroxide emulsion are mixed and heated to 100° C. to 120° C. and reacted for 2.5 h to 3 h to obtain a phosphoric acid-based flame-retardant unsaturated polyester resin.

2. The method for synthesizing a phosphoric acid-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 phosphoric acid-based flame-retardant unsaturated polyester resin according to claim 1, characterized in that: The phosphorus oxychloride monomers include phenyl phosphorus oxychloride, phenyl dichlorophosphate or methyl dichlorophosphate.

4. The method for synthesizing a phosphoric acid-based flame-retardant unsaturated polyester resin according to claim 1, characterized in that: The preparation method of the polyurethane-coated aluminum hydroxide emulsion comprises the following steps: Diisocyanate, polyol, aluminum hydroxide and dibutyltin dilaurate are mixed in a weight ratio of 13-15:40-44:21-23:0.2-0.3, heated to 60° C.-65° C. and pre-reacted for 1.5 h-2 h to obtain a polyurethane prepolymer; The polyurethane prepolymer and dimethylol propionic acid are heated to 75°C~80°C for chain extension reaction for 1h~2h, then cooled to 40°C and triethylamine is added for reaction for 30min~40min, and then deionized water is added and stirred at high speed to obtain polyurethane-coated aluminum hydroxide emulsion.

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

6. The method for synthesizing a phosphoric acid-based flame-retardant unsaturated polyester resin according to claim 4, characterized in that: The polyol includes polypropylene glycol 400.

7. The method for synthesizing a phosphoric acid-based flame-retardant unsaturated polyester resin according to claim 4, characterized in that: The weight ratio of the diisocyanate: dimethylolpropionic acid: triethylamine is 1:0.5:0.

4.

8. The method for synthesizing a phosphoric acid-based flame-retardant unsaturated polyester resin according to claim 4, characterized in that: The amount of deionized water added is 5 to 6 times the total weight of the polyurethane prepolymer and dimethylol propionic acid.

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

3.

10. A phosphoric acid-based flame-retardant unsaturated polyester resin prepared by the method for synthesizing a phosphoric acid-based flame-retardant unsaturated polyester resin according to any one of claims 1 to 9.

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