Thermosetting unsaturated polyester resin as well as preparation method and application thereof

Abstract

The invention discloses thermosetting unsaturated polyester resin as well as a preparation method and application thereof, and belongs to the technical field of unsaturated polyester resin. The raw materials comprise the following components in parts by weight: 270 to 380 parts of neopentyl glycol, 90 to 150 parts of ethylene glycol, 400 to 570 parts of isophthalic acid, 0.4 to 1.0 part of an antioxidant, 0.3 to 0.8 part of a catalyst, 80 to 170 parts of propylene glycol, 260 to 380 parts of maleic anhydride, 0.03 to 0.09 part of a first polymerization inhibitor, 0.1 to 0.3 part of a second polymerization inhibitor, 0.1 to 0.4 part of a third polymerization inhibitor and 800 to 900 parts of styrene. The thermosetting unsaturated polyester resin disclosed by the invention has relatively high mechanical properties and corrosion resistance after being cured, still can keep relatively high mechanical properties after being corroded by acid and alkali, is high in bending deformation resistance, and can be applied to thermosetting trenchless repair of buildings or pipelines.

Description

Technical Field

[0001] The invention discloses a thermosetting unsaturated polyester resin and a preparation method and application thereof, belonging to the technical field of unsaturated resins for construction. Background Art

[0002] The traditional repair method of excavating roads to replace pipelines is not only costly, but also seriously affects urban traffic and residents' lives. Therefore, efficient, economical and environmentally friendly trenchless repair technology has emerged. In-situ curing is one of the most widely used trenchless pipeline repair technologies. It uses a small entrance on the surface or an existing inspection well to place a resin-impregnated hose into the original pipeline by flipping or pulling. It uses various technologies and materials to repair or replace underground pipelines in situ. After curing, it forms a pipeline lining repair method, which significantly reduces the repair cost, shortens the construction period, and reduces the impact on public life.

[0003] Thermosetting trenchless repair resin is a high molecular polymer material. The molecular chains are chemically cross-linked together. The molecular structure is relatively stable. The molecular chains will not melt or flow during the heating process. The molecular chains form a rigid three-dimensional network structure through cross-linking and have excellent comprehensive performance.

[0004] The trenchless thermosetting resins currently prepared by the existing technology are usually epoxy resins and phenolic resins, which are not only expensive but also have the disadvantages of high viscosity, poor wettability, long curing cycle, low mechanical properties and poor corrosion resistance.

[0005] Patent CN 114605778 A discloses a non-excavation repair CIPP thermosetting resin, which is composed of the following components by weight: 50-60 parts of bisphenol F epoxy resin monomer, 30 parts of styrene monomer, 36-40 parts of o-cresyl glycidyl ether, 3-8 parts of hardener system, 3-6 parts of modifier system, 7-19 parts of thickener system, 1.2-2.0 parts of thermal initiator system, and 0.2 parts of defoamer. The non-excavation repair CIPP thermosetting resin prepared by this patent has the advantages of long storage time, rapid reaction at more than 60°C, simple operation, and high strength, but the corrosion resistance of the resin is still low and the cost price of bisphenol F epoxy resin is high, which is 2-3 times the price of unsaturated polyester resin. Summary of the invention

[0006] The technical problem to be solved by the present invention is: to overcome the deficiencies of the prior art and provide a thermosetting unsaturated polyester resin and a preparation method and application thereof, wherein the thermosetting unsaturated polyester resin has high mechanical properties and corrosion resistance after curing, can still maintain high mechanical properties after acid and alkali corrosion, and has strong resistance to bending deformation.

[0007] The technical solution adopted by the present invention to solve the technical problem is: the preparation method of the thermosetting unsaturated polyester resin comprises the following raw materials in parts by weight: 270-380 parts of neopentyl glycol, 90-150 parts of ethylene glycol, 400-570 parts of isophthalic acid, 0.4-1.0 parts of antioxidant, 0.3-0.8 parts of catalyst, 80-170 parts of propylene glycol, 260-380 parts of maleic anhydride, 0.03-0.09 parts of a first polymerization inhibitor, 0.1-0.3 parts of a second polymerization inhibitor, 0.1-0.4 parts of a third polymerization inhibitor and 800-900 parts of styrene.

[0008] Preferably, the thermosetting unsaturated polyester resin is characterized in that the raw materials include the following components in parts by weight: 310.6-356.4 parts of neopentyl glycol, 112.1-138.7 parts of ethylene glycol, 463.7-506.2 parts of isophthalic acid, 0.6-0.8 parts of antioxidant, 0.4-0.6 parts of catalyst, 102.9-134.3 parts of propylene glycol, 292.2-354.9 parts of maleic anhydride, 0.05-0.07 parts of a first inhibitor, 0.15-0.23 parts of a second inhibitor, 0.11-0.18 parts of a third inhibitor, and 840-860 parts of styrene.

[0009] The molar ratio of unsaturated acid to saturated acid in the raw material is 1.0-1.3: 1. Preferably, the molar ratio of unsaturated acid to saturated acid in the raw material is 1.03-1.28:1.

[0010] The molar ratio of total alcohol to total acid in the raw material is 1.02-1.13:1.

[0011] The catalyst is zinc acetate, or a mixture of dibutyltin oxide and zinc acetate in a weight ratio of 1:3-5.

[0012] The antioxidant is triphenyl phosphite or 2,5-di-tert-butylhydroquinone.

[0013] The first polymerization inhibitor, the second polymerization inhibitor, and the third polymerization inhibitor are at least one of hydroquinone, p-benzoquinone, tert-butylhydroquinone, o-methylhydroquinone, methylhydroquinone, and tert-butylhydroquinone. The first polymerization inhibitor, the second polymerization inhibitor, and the third polymerization inhibitor may have the same components or different components.

[0014] Preferably, the first polymerization inhibitor is at least one of hydroquinone, para-benzoquinone, and o-methylhydroquinone; the second polymerization inhibitor is at least one of methylhydroquinone, hydroquinone, para-benzoquinone, and tert-butylhydroquinone; and the third polymerization inhibitor is at least one of tert-butylhydroquinone, hydroquinone, and para-benzoquinone.

[0015] The preparation method of the thermosetting unsaturated polyester resin comprises the following steps: 1) Add neopentyl glycol, ethylene glycol, isophthalic acid, antioxidant and catalyst into the reactor according to weight. Under the protection of inert gas, raise the temperature of the reactor to 187-193°C and keep the temperature for 40-65 minutes; 2) Raise the temperature of the reactor to 213-217°C and keep the temperature to react until the acid value reaches 7-11 mgKOH / g; 3) Cooling to 117-123°C, adding propylene glycol, maleic anhydride and the first inhibitor into the reaction kettle according to weight; 4) Raise the temperature of the reactor to 178-182°C and keep the temperature for 40-65 minutes; 5) Raise the temperature to 206-212℃, keep the temperature and react until the acid value is 15-24 mgKOH / g and the cone-plate viscosity is 4000-5000 mPa·s; 6) Cool down to 177-183°C and add the second polymerization inhibitor into the reactor by weight; 7) Cool down to 147-153°C, add the third polymerization inhibitor and styrene into the reactor by weight, stir evenly, and cool down to 58-62°C to obtain unsaturated polyester resin.

[0016] The heating rate of the heating in steps 1), 2), 4) and 5) is 12-18°C / h. Preferably, the heating rate of the heating in steps 1), 2), 4) and 5) is 15-17°C / h. Preferably, the cooling rate of the cooling in steps 3), 6) and 7) is 9-19°C / h. Further preferably, the cooling rate of the cooling in steps 3), 6) and 7) is 15-17°C / h.

[0017] The application of the thermosetting unsaturated polyester resin or the thermosetting unsaturated polyester resin prepared by the preparation method according to any one of claims 8 to 9 is characterized by being used in the field of thermosetting trenchless repair of buildings or pipelines.

[0018] The technical solution of the present invention is described as follows: Preferably, the total mass of neopentyl glycol, ethylene glycol and propylene glycol is greater than the mass of isophthalic acid. This design makes the mass of the diols composed of neopentyl glycol, ethylene glycol and propylene glycol greater than the mass of diphthalic acid, which can improve the crystallinity of the resin and increase the compatibility of polyester and styrene.

[0019] First, neopentyl glycol, ethylene glycol and propylene glycol cooperate with each other. After neopentyl glycol is introduced into the raw materials, the two methyl groups in neopentyl glycol provide shield-shaped protection for the ester bond, making the resin have excellent corrosion resistance; its symmetrical structure can also make the resin have high hydrolysis stability and easily increase crystallinity. If neopentyl glycol is lacking, it will have an adverse effect on the chemical resistance of the resin, and the corrosion resistance of the unsaturated polyester resin is not ideal. If propylene glycol is not added, it will have an adverse effect on the elongation and toughness of the resin. If ethylene glycol is not added, it will have an adverse effect on the poor compatibility of polyester with styrene.

[0020] Second, isophthalic acid cannot be replaced by other dicarboxylic acids. Isophthalic acid has two carboxyl functional groups at the meta position. After isophthalic acid is introduced into the raw materials, the ester bonds on the molecular chain of isophthalic acid polyester are protected by the steric hindrance effect of isophthalic acid, and its ester bonds are less susceptible to water and other corrosive media. Therefore, the performance of glass fiber reinforced pipes made of isophthalic acid polyester resin is better. The combined effect of isophthalic acid and neopentyl glycol makes unsaturated polyester resin easy to manufacture, low cost, excellent comprehensive mechanical properties, and resistant to acid, alkali and various solvents.

[0021] In step 2), the role of adding propylene glycol and maleic anhydride when adding the first inhibitor is that the polyester can form a long-chain molecule with a uniform structure. After the saturated acid and diol have been preliminarily reacted to form a monoester structure in step 1), propylene glycol and maleic anhydride are added to make the unsaturated polyester form a long-chain molecule with a uniform structure, and the molecular weight distribution is relatively uniform, thereby improving the product quality and the chemical resistance of the resin. In addition, maleic anhydride is beneficial to the process of the synthesis reaction, and improves the yield and performance stability of the product. The applicant has found that if propylene glycol and maleic anhydride are added in step 1), the two reactants containing the same functional groups in the polyester will participate in the reaction at different speeds, thereby adversely affecting the dispersion and unreasonable arrangement of the polyester molecular composition structure, resulting in poor physical and chemical properties of the unsaturated polyester resin. Therefore, the best solution is to add propylene glycol, maleic anhydride and the first inhibitor together in step 2).

[0022] The catalyst is a mixture of zinc acetate or dibutyltin oxide and zinc acetate in a weight ratio of 1:3-5. Zinc acetate or dibutyltin oxide and zinc acetate can be used together to enhance synergy. The catalytic effect is improved, thereby improving the reaction efficiency of unsaturated polyester resin, catalyzing the polycondensation reaction between alcohol and acid, and improving the physical and chemical properties of the resin. Preferably, the catalyst is a mixture of zinc acetate or dibutyltin oxide and zinc acetate in a weight ratio of 1:4.

[0023] The molar ratio of the unsaturated acid to the saturated acid in the raw material is 1.0-1.3. It is understood that the molar ratio can be any specific value of 1.0, 1.1, 1.2, 1.3 or any value within the range of 1.0-1.3. When the molar ratio of the unsaturated acid to the saturated acid in the raw material is low, the chemical reaction progresses slowly and the comprehensive mechanical properties of the obtained product are poor; when the molar ratio of the unsaturated acid to the saturated acid in the raw material is high, the comprehensive mechanical properties of the obtained product are poor, the corrosion resistance is poor, etc.

[0024] In the present invention, the calculation formula of the molar ratio of unsaturated acid to saturated acid in the raw material is: The molar ratio of unsaturated acid to saturated acid in the raw material = moles of maleic anhydride / moles of isophthalic acid In the present invention, the molar ratio of total alcohol to total acid in the raw material is 1.02-1.13. It can be understood that the molar ratio can be any specific value of 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, 1.08, 1.09, 1.10, 1.11, 1.12, 1.13 or any value within the range of 1.02-1.13. When the molar ratio of total alcohol to total acid in the raw material is low, the terminal acid value is too high, the carboxyl end is excessive, the acid groups that do not participate in the reaction are more, the small molecule polyester chains are more, and the mechanical properties of the final product are poor; when the molar ratio of total alcohol to total acid in the raw material is high, the terminal acid value is too low, the carboxyl end is less and the density is low, which will cause the final polycondensation reaction to slow down, or even cause the polycondensation reaction to fail.

[0025] In the present invention, the calculation formula of the molar ratio of total alcohol to total acid in the raw material is: The molar ratio of total alcohol to total acid in the reaction raw materials = (moles of neopentyl glycol + moles of ethylene glycol + moles of propylene glycol) / (moles of maleic anhydride + moles of isophthalic acid) By controlling the reaction acid value of step (2) within the range of 7-11 mgKOH / g, the product quality of the unsaturated polyester resin can be stabilized, and the content of the terminal carboxyl group can be stabilized within a certain range, thereby effectively controlling the product quality grade, so that the product quality reaches a high level in terms of hardness, tensile strength, bending, impact performance, etc., and provides the required production process conditions for the subsequent reprocessing of products.

[0026] Compared with the prior art, the thermosetting unsaturated polyester resin and the preparation method and application thereof of the present invention have the following beneficial effects: 1. The thermosetting unsaturated polyester resin of the present invention has high mechanical properties and corrosion resistance after curing, and can still maintain high mechanical properties after acid and alkali corrosion, and has strong anti-bending deformation ability. The present invention introduces a certain amount of neopentyl glycol into the synthetic raw materials of the thermosetting unsaturated polyester resin. Neopentyl glycol is an alcohol with a symmetrical structure. When combined with the polyester molecular chain, two large methyl groups provide shield-shaped protection for the ester bond, so that the resin has excellent corrosion resistance; its symmetrical structure can also make the resin have high hydrolysis stability and easily increase crystallinity. Mixing neopentyl glycol with ethylene glycol can improve compatibility with styrene. The ester bond on the isophthalic acid polyester molecular chain is protected by the steric hindrance effect of isophthalic acid, and is less susceptible to water and other various corrosive media. Therefore, the performance of the glass fiber reinforced pipe made of isophthalic acid polyester resin is more excellent. The combined action of isophthalic acid and neopentyl glycol makes the unsaturated polyester resin easy to manufacture, low cost, excellent comprehensive mechanical properties, and resistant to acid, alkali and various solvents. Acidic or alkaline fluids are often transported in pipelines. After the thermosetting unsaturated polyester resin of the present invention is used for pipeline repair, the chemical resistance of the pipeline is better and it can still maintain high mechanical properties under acidic or alkaline corrosion.

[0027] 2. The thermosetting unsaturated polyester resin of the present invention has low viscosity, good wetting performance and short curing time. The present invention adopts a first polymerization inhibitor, a second polymerization inhibitor and a third polymerization inhibitor, and the three polymerization inhibitors are added at different preparation stages, so that the unsaturated polyester resin has low viscosity and good wetting performance, so that it can penetrate into fine cracks in pipelines, has a faster thickening speed, can fill and bond cracks, and shortens the curing time.

[0028] 3. The thermosetting unsaturated polyester resin of the present invention saves manufacturing costs. By further controlling the molar ratio of unsaturated acid to saturated acid in the raw materials and the molar ratio of total alcohol to total acid in the raw materials, the comprehensive mechanical properties of the unsaturated polyester resin can be further improved and the chemical resistance can be improved, thereby improving various properties of the thermosetting trenchless pipe repair resin.

[0029] 4. The preparation method of the thermosetting unsaturated polyester resin of the present invention can improve the corrosion resistance and mechanical properties. The preparation method controls the synthesis conditions of the unsaturated polyester to ensure the normal reaction and the product quality.

[0030] 5. The thermosetting unsaturated polyester resin of the present invention can be applied to thermosetting trenchless repair of buildings or pipelines. The unsaturated polyester resin has high mechanical properties and still has high resistance to bending deformation after acid and alkali corrosion. It is suitable for repairing pipelines that transport acidic or alkaline fluids, or repairing water seepage and leakage caused by cracks in buildings. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below in conjunction with Table 1 and specific examples, but the implementation of the present invention is not limited thereto. Example 3 is the best example. The formulas of Examples 1-6 are shown in Table 1.

[0032] Neopentyl glycol, propylene glycol, ethylene glycol, maleic anhydride, isophthalic acid, and styrene: analytical grade, all purchased from Aladdin Reagent Co., Ltd.; antioxidant: triphenyl phosphite, purchased from Jiangsu Evergreen New Materials Technology Co., Ltd.; catalyst: zinc acetate, purchased from Tianjin Jinhui Taiya Chemical Reagent Co., Ltd.; hydroquinone, purchased from Weifang Tongrun Chemical Co., Ltd.; methylhydroquinone, purchased from Zhongtao New Materials Co., Ltd.; p-tert-butylcatechol, purchased from Shanghai Jizhi Biochemical Technology Co., Ltd.

[0033] Table 1 Ratio of raw materials used in the examples (by weight) .

[0034] Example 1 The preparation method of the thermosetting unsaturated polyester resin of this embodiment comprises the following steps: 1) Add neopentyl glycol, ethylene glycol, isophthalic acid, antioxidant and catalyst into the reactor by weight. Under the protection of inert gas, raise the temperature of the reactor to 187℃ at a rate of 12℃ / h. Keep the water warm for 40 minutes. The nitrogen flow rate is 5m 3 / h; 2) Raise the temperature of the reactor to 213°C at a rate of 12°C / h and keep the temperature to react until the acid value reaches 11 mgKOH / g; 3) Cooling down to 123°C at a rate of 18°C / h, adding propylene glycol, maleic anhydride and the first inhibitor into the reaction kettle according to weight; 4) Raise the temperature of the reactor to 182°C at a rate of 18°C / h and keep the temperature for 65 minutes; 5) Raise the temperature to 206°C at a rate of 18°C / h and keep the temperature to react until the acid value reaches 24 mgKOH / g and the cone-plate viscosity reaches 4000 mPa·s; 6) Cool down to 183°C at a rate of 18°C / h, and add the second polymerization inhibitor into the reactor by weight; 7) Cool down to 147°C at a rate of 12°C / h, add the third polymerization inhibitor and styrene into the reactor by weight, stir evenly, and cool down to 62°C to obtain unsaturated polyester resin.

[0035] Example 2 The preparation method of the thermosetting unsaturated polyester resin of this embodiment comprises the following steps: 1) Add neopentyl glycol, ethylene glycol, isophthalic acid, antioxidant and catalyst into the reactor by weight. Under the protection of inert gas, raise the temperature of the reactor to 193℃ at a rate of 18℃ / h. Keep the water at the temperature for 65 minutes. The nitrogen flow rate is 5m 3 / h; 2) Raise the temperature of the reactor to 217°C at a rate of 18°C / h and keep the temperature to react until the acid value reaches 7mgKOH / g; 3) Cooling down to 117°C at a rate of 12°C / h, adding propylene glycol, maleic anhydride and the first inhibitor into the reaction kettle according to weight; 4) Raise the temperature of the reactor to 178°C at a rate of 12°C / h and keep the temperature for 40 minutes; 5) Raise the temperature to 212°C at a rate of 12°C / h and keep the temperature to react until the acid value reaches 15 mgKOH / g and the cone-plate viscosity reaches 5000 mPa·s; 6) Cool down to 177°C at a rate of 12°C / h, and add the second polymerization inhibitor into the reactor by weight; 7) Cool down to 153°C at a rate of 18°C / h, add the third polymerization inhibitor and styrene into the reactor by weight, stir evenly, and cool down to 58°C to obtain unsaturated polyester resin.

[0036] Example 3 The preparation method of the thermosetting unsaturated polyester resin of this embodiment comprises the following steps: 1) Add neopentyl glycol, ethylene glycol, isophthalic acid, antioxidant and catalyst into the reactor according to weight. Under the protection of inert gas, raise the temperature of the reactor to 190℃ at a rate of 17℃ / h. Keep the water warm for 60 minutes. The nitrogen flow rate is 5m 3 / h; 2) Raise the temperature of the reactor to 215°C at a rate of 17°C / h and keep the temperature to react until the acid value reaches 10mgKOH / g; 3) Cooling down to 120°C at a rate of 15°C / h, adding propylene glycol, maleic anhydride and the first inhibitor into the reaction kettle according to weight; 4) Raise the temperature of the reactor to 180°C at a rate of 17°C / h and keep the temperature for 60 minutes; 5) Raise the temperature to 210°C at a rate of 17°C / h and keep the temperature to react until the acid value reaches 20 mgKOH / g and the cone-plate viscosity reaches 4500 mPa·s; 6) Cool down to 180°C at a rate of 15°C / h, and add the second polymerization inhibitor into the reactor by weight; 7) Cool down to 150°C at a rate of 15°C / h, add the third polymerization inhibitor and styrene into the reactor by weight, stir evenly, and cool down to 58-62°C to obtain unsaturated polyester resin.

[0037] Example 4 The preparation method is the same as Example 3.

[0038] Example 5 The preparation method is the same as Example 3.

[0039] Example 6 The preparation method is the same as Example 3.

[0040] Comparative Example 1 This comparative example is the same as Example 3, except that no neopentyl glycol is added in step 1).

[0041] Comparative Example 2 This comparative example is the same as Example 3, except that in step 1), the total mass of neopentyl glycol, ethylene glycol and propylene glycol is less than the mass of isophthalic acid.

[0042] In step 1), the following adjustments are made: 165 parts of neopentyl glycol and 195.4 parts of ethylene glycol; In step 2), the amount is adjusted to: 141.2 parts of propylene glycol.

[0043] Comparative Example 3 This comparative example is the same as Example 3, except that propylene glycol and maleic anhydride are added in step 1).

[0044] 1) Add neopentyl glycol, ethylene glycol, isophthalic acid, propylene glycol, maleic anhydride, antioxidant and catalyst into the reactor by weight. Under the protection of inert gas, raise the temperature of the reactor to 190℃ at a rate of 17℃ / h. Keep the water out and react for 60 minutes. The nitrogen flow rate is 5m 3 / h; 2) Same as Example 3; 3) Cooling down to 120°C at a rate of 15°C / h, adding the first polymerization inhibitor into the reactor by weight; 4)-7) Same as Example 3.

[0045] Performance Testing 1. Viscosity and curing time test 1) Viscosity: The thermosetting unsaturated polyester resins obtained in the examples and comparative examples were subjected to viscosity tests, and the rotational viscosity at 25°C was measured and recorded in Table 2, in units of mPa·s (25°C); the lower the viscosity of the unsaturated polyester resin, the better its wettability to the glass fiber; 2) Curing time: After adding the photoinitiator to the thermosetting unsaturated polyester resin produced in the examples and comparative examples, the light curing time observed at 25° C. is recorded in Table 2 in minutes.

[0046] 2. Mechanical properties test 2% of the accelerator cobalt isooctanoate was added to the thermosetting unsaturated polyester resin obtained in the embodiment and the comparative example respectively, and the mixture was stirred evenly. Then, 2% of the initiator methyl ethyl ketone peroxide was added, and the mixture was stirred evenly. The mixture was poured into a steel mold with a size of 350 mm×300 mm×5 mm, and cured at 23±2°C for 24 hours to obtain a thermosetting unsaturated polyester resin casting. The performance test was carried out according to the following method, and the specific results are shown in Table 2.

[0047] 1) Tensile strength: tested in accordance with standard GB / T 2567-2008; 2) Tensile elastic modulus: tested in accordance with standard GB / T 2567-2008; 3) Elongation at break: Tested in accordance with standard GB / T 2567-2008; 4) Bending strength: tested in accordance with standard GB / T 2567-2008; 5) Flexural modulus: tested in accordance with standard GB / T 2567-2008; 6) Impact strength: tested in accordance with standard GB / T 2567-2008; 7) Heat deformation temperature: Tested in accordance with standard GB / T 2567-2008; 3. Chemical corrosion resistance test 1) Chemical resistance: The synthetic unsaturated polyester resin was used to make a resin casting, and the casting was tested for chemical resistance according to standard GB / T 3857-2017. The casting soaked in chemical media was tested for bending properties according to standard GB / T 2567-2008. The flexural strength and flexural modulus retention rates of the castings after immersion in different chemical media for 28 days are shown in Table 3.

[0048] Table 2 Performance data of Examples 1-6 and Comparative Examples 1-3 .

[0049] Table 3 Comparison of flexural strength and flexural modulus retention rate of castings after immersion in different chemical media for 28 days .

[0050] It can be seen from Table 2-3 that: The thermosetting unsaturated polyester resins described in Examples 1-6 of the present invention have better comprehensive mechanical properties and the products have better corrosion resistance.

[0051] In Comparative Example 1, no neopentyl glycol was added, and the comprehensive mechanical properties thereof were significantly reduced, and the corrosion resistance of the product was significantly reduced.

[0052] The total amount of diol added in the raw material in Comparative Example 2 is relatively low in weight, and its comprehensive mechanical properties and corrosion resistance are not as good as those of the embodiments of the present invention, which indicates that the use of a specific amount of neopentyl glycol can significantly improve the comprehensive mechanical properties of the resin casting and improve the corrosion resistance of the product.

[0053] In Comparative Example 3, propylene glycol and maleic anhydride were added in step 1), and the mechanical properties after corrosion were poor.

[0054] It can be seen that, after the introduction of neopentyl glycol into the synthetic raw material of the thermosetting unsaturated polyester resin, the synergistic effect of neopentyl glycol and isophthalic acid improves the comprehensive mechanical properties of the resin, and effectively improves the chemical resistance of the thermosetting unsaturated polyester resin. The combined effect of the two makes the thermosetting unsaturated polyester resin easy to manufacture, low in cost, excellent in comprehensive mechanical properties, and resistant to corrosion by acids, alkalis and various solvents.

[0055] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still belongs to the protection scope of the technical solution of the present invention.

Claims

1. A thermosetting unsaturated polyester resin, characterized in that: The raw materials include the following components in parts by weight: 270-380 parts of neopentyl glycol, 90-150 parts of ethylene glycol, 400-570 parts of isophthalic acid, 0.4-1.0 parts of antioxidant, 0.3-0.8 parts of catalyst, 80-170 parts of propylene glycol, 260-380 parts of maleic anhydride, 0.03-0.09 parts of a first polymerization inhibitor, 0.1-0.3 parts of a second polymerization inhibitor, 0.1-0.4 parts of a third polymerization inhibitor, and 800-900 parts of styrene.

2. The thermosetting unsaturated polyester resin according to claim 1, characterized in that The raw materials include the following components in parts by weight: 310.6-356.4 parts of neopentyl glycol, 112.1-138.7 parts of ethylene glycol, 463.7-506.2 parts of isophthalic acid, 0.6-0.8 parts of antioxidant, 0.4-0.6 parts of catalyst, 102.9-134.3 parts of propylene glycol, 292.2-354.9 parts of maleic anhydride, 0.05-0.07 parts of a first polymerization inhibitor, 0.15-0.23 parts of a second polymerization inhibitor, 0.11-0.18 parts of a third polymerization inhibitor, and 840-860 parts of styrene.

3. The thermosetting unsaturated polyester resin according to claim 1, characterized in that: The molar ratio of unsaturated acid to saturated acid in the raw material is 1.0-1.3:

1.

4. The thermosetting unsaturated polyester resin according to claim 1, characterized in that: The molar ratio of total alcohol to total acid in the raw material is 1.02-1.13:

1.

5. The thermosetting unsaturated polyester resin according to claim 1, characterized in that: The catalyst is zinc acetate, or a mixture of dibutyltin oxide and zinc acetate in a weight ratio of 1:3-5.

6. The thermosetting unsaturated polyester resin according to claim 1, characterized in that: The antioxidant is triphenyl phosphite or 2,5-di-tert-butylhydroquinone.

7. The thermosetting unsaturated polyester resin according to claim 1, characterized in that: The first polymerization inhibitor, the second polymerization inhibitor, and the third polymerization inhibitor are at least one of hydroquinone, p-benzoquinone, tert-butylhydroquinone, o-methylhydroquinone, methylhydroquinone, and tert-butylhydroquinone.

8. The method for preparing a thermosetting unsaturated polyester resin according to any one of claims 1 to 7, characterized in that: The steps include: 1) Add neopentyl glycol, ethylene glycol, isophthalic acid, antioxidant and catalyst into the reactor according to weight. Under the protection of inert gas, raise the temperature of the reactor to 187-193°C and keep the temperature for 40-65 minutes; 2) Raise the temperature of the reactor to 213-217°C and keep the temperature to react until the acid value reaches 7-11 mgKOH / g; 3) Cooling to 117-123°C, adding propylene glycol, maleic anhydride and the first inhibitor into the reaction kettle according to weight; 4) Raise the temperature of the reactor to 178-182°C and keep the temperature for 40-65 minutes; 5) Raise the temperature to 206-212℃, keep the temperature and react until the acid value is 15-24 mgKOH / g and the cone-plate viscosity is 4000-5000 mPa·s; 6) Cool down to 177-183°C and add the second polymerization inhibitor into the reactor by weight; 7) Cool down to 147-153°C, add the third polymerization inhibitor and styrene into the reactor by weight, stir evenly, and cool down to 58-62°C to obtain unsaturated polyester resin.

9. The method for preparing a thermosetting unsaturated polyester resin according to claim 8, characterized in that: The heating rate of the heating in steps 1), 2), 4) and 5) is 12-18°C / h.

10. Use of the thermosetting unsaturated polyester resin according to any one of claims 1 to 7 or the thermosetting unsaturated polyester resin prepared by the preparation method according to any one of claims 8 to 9, characterized in that: Applications in the field of thermosetting trenchless repair of buildings or pipelines.