A modified urea solution-thickened photocurable unsaturated polyester resin and its preparation method

Abstract

This invention discloses a modified urea solution-thickened photocurable unsaturated polyester resin and its preparation method, belonging to the technical field of unsaturated polyester resins. The raw materials, by weight, comprise: 29-37 parts maleic anhydride, 46-51 parts saturated diacid / anhydride, 55-61 parts diol, 62-68 parts styrene, 2-8 parts modified urea solution, 0.6-0.8 parts photoinitiator, 0.02-0.08 parts polymerization inhibitor, 0.06-0.08 parts antioxidant, and 0.04-0.06 parts catalyst. This invention generates a three-dimensional network structure through modified urea solution, exhibiting thixotropy and fluidity, preventing sedimentation and improving anti-sagging properties. The synthesized resin has high mechanical strength, excellent thickening properties, improved transparency and UV light penetration, and shortened photocuring time, meeting the requirements for thick-walled CIPP.

Description

Technical Field

[0001] This invention relates to the field of unsaturated polyester resin technology, and in particular to a modified urea solution-thickened photocurable unsaturated polyester resin and its preparation method. Background Technology

[0002] CIPP (Cured-In-Place Pipe) is a technology used for repairing and replacing underground pipelines. It mainly involves installing a new liner inside the existing pipeline and curing it through heat, ultraviolet light, or chemical reactions to form a new inner liner. CIPP technology has many advantages in pipeline repair and replacement.

[0003] Currently, magnesium oxide paste is mostly used as a thickener for pipe repair resins in CIPP technology. However, since magnesium oxide paste is a white paste, its addition makes the resin less clear, affecting the penetration of ultraviolet light and thus the subsequent curing performance of the resin. In addition, the preparation process of magnesium oxide paste thickener is complicated, which not only consumes a lot of time and labor costs, but also makes it impossible to achieve a controllable range for the thickening speed in the later stage, especially at low temperatures, where the reaction rate of magnesium oxide is relatively slow.

[0004] For example, patent CN118459960A discloses a thickener for in-situ curing pipe (CIPP) repair resin, which consists of the following components by weight: 0.9-0.99 parts of inactive carrier resin, 0.74-0.88 parts of inorganic filler, 0.0054-0.009 parts of wetting and dispersing agent, and 0.3-0.4 parts of thickening accelerator, wherein the main component of the inorganic filler is magnesium oxide. This patent is a magnesium oxide paste-type thickener. Although it has a good thickening effect in CIPP applications, the resin still does not solve the problem that the resin cannot be clarified after adding magnesium oxide paste, has poor ultraviolet light penetration, and affects the subsequent photocuring effect. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a modified urea solution-thickened photocurable unsaturated polyester resin and its preparation method. The resin synthesized by this method has high mechanical strength, excellent thickening properties, can replace magnesium oxide paste, improves transparency and ultraviolet light penetration, shortens photocuring time, meets the requirements of thick-walled CIPP, and is suitable for photocurable unsaturated polyester resins.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a modified urea solution thickened photocurable unsaturated polyester resin, the raw materials comprising the following components by weight: maleic anhydride 29-37 parts, saturated diacid / anhydride 46-51 parts, diol 55-61 parts, styrene 62-68 parts, modified urea solution 2-8 parts, photoinitiator 0.6-0.8 parts, polymerization inhibitor 0.02-0.08 parts, antioxidant 0.06-0.08 parts, catalyst 0.04-0.06 parts.

[0007] The formulation of this invention introduces a modified urea solution to construct a dynamic three-dimensional network structure, giving the resin unique thixotropic properties and controllable flowability. This not only prevents filler sedimentation but also significantly improves anti-sagging performance, ensuring uniformity in thick-wall construction.

[0008] The unsaturated polyester resin synthesized in this invention possesses both high mechanical strength and excellent thickening properties, completely replacing the traditional magnesium oxide paste system and fundamentally solving the problems of turbidity and severe ultraviolet light scattering caused by magnesium oxide. The transparency of the modified urea allows the resin to maintain high light transmittance, significantly improving ultraviolet light penetration efficiency. Combined with a photoinitiation system, it can achieve deep and rapid curing, meeting the curing depth and aging requirements for thick-walled CIPP repair.

[0009] The system of this invention achieves precise control of thickening rate through intermolecular hydrogen bonding, avoids the risk of inorganic filler phase separation, maintains stable thickening behavior at low temperatures, and takes into account both the leveling properties during construction and the dense structure after curing. It provides an innovative solution for pipeline repair of photocurable unsaturated polyester resin under complex working conditions.

[0010] As a further aspect of this invention, the saturated diacid / anhydride is one or more of phthalic anhydride, isophthalic acid, and terephthalic acid. Although containing benzene rings, phthalic anhydride, isophthalic acid, and terephthalic acid can all be classified as "saturated diacid / anhydride" in the synthesis of unsaturated polyester resins. Their benzene ring structures enhance the resin's heat resistance and mechanical strength, while copolymerizing with maleic anhydride to form regular chain segments, improving intermolecular forces and synergistically enhancing the three-dimensional network of the modified urea solution. Utilizing their isomerism can optimize resin crystallinity, avoid local stress concentration, and enhance the crack resistance after thick-walled curing. These phthalic anhydride compounds have moderate reactivity, ensuring a stable and controllable polycondensation process, and the resulting resin possesses both high light transmittance and excellent rheological properties.

[0011] As a further aspect of this invention, the diol is one or more selected from propylene glycol, ethylene glycol, diethylene glycol, and neopentyl glycol. The selected diol can precisely control the flexibility and spatial configuration of the polyester molecular chain. For example, short-chain diols (such as ethylene glycol) enhance intermolecular forces and improve resin rigidity; diethylene glycol containing ether bonds imparts chain mobility and improves low-temperature thickening stability; the branched structure of neopentyl glycol inhibits crystallization and synergistically modifies the urea network to enhance transparency. These diols can be selected and combined according to environmental requirements during application. The combination of polyols optimizes the polycondensation reaction activity and molecular weight distribution, forming a regular main chain structure that provides a stable framework for the thickening system and ensures a balance between the toughness and hydrolysis resistance of the cured resin.

[0012] As a further aspect of this invention, the modified urea solution is RHEOBYK-410, preferably in the form of 4-6 parts by weight. Using RHEOBYK-410 as the modified urea solution, its unique hydrogen-bonded rheology modifier properties allow for the directional construction of a three-dimensional network structure, endowing the resin with excellent shear-thinning properties and a high thixotropic index. It forms a strong gel state under static conditions, effectively preventing filler sedimentation; during application shearing, it rapidly reduces viscosity, ensuring uniform coating of thick-walled structures. Its transparent liquid properties are perfectly compatible with the resin system, avoiding transmittance loss caused by magnesium oxide thickening, thus meeting the core requirements of CIPP remediation.

[0013] As a further embodiment of the present invention, the photoinitiator is one or more of (2,4,6-trimethylbenzoyl)diphenylphosphine oxide, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, ethyl 2,4,6-trimethylbenzoylphenylphosphonate, 2-isopropylthioxanthone, and 2-hydroxy-2-methylphenylpropane-1-one. The selected photoinitiator, through the synergistic effect of broad-spectrum absorption and efficient cleavage, covers the dominant ultraviolet wavelength range, significantly improving the deep curing efficiency.

[0014] As a further aspect of the present invention, the polymerization inhibitor is selected from one or more of hydroquinone, p-benzoquinone, methylhydroquinone, or tert-butylhydroquinone. The selected polymerization inhibitor efficiently captures free radicals through its phenolic hydroxyl groups, precisely controlling the stability of the prepolymer. Its thermal decomposition characteristics are dynamically matched with the photoinitiation system, suppressing side reactions during storage and rapidly deactivating upon UV triggering. This ensures that the thickening resin system achieves an optimal balance between application rheology and photocuring rate, avoiding gel defects.

[0015] The antioxidant is triphenyl phosphite or 2,5-di-tert-butylhydroquinone. The catalyst is zinc acetate, or a mixture of dibutyltin oxide and zinc acetate.

[0016] A method for preparing a modified urea solution-thickened, light-curable unsaturated polyester resin, comprising the following steps:

[0017] (1) Add saturated diacid / anhydride, antioxidant and catalyst, half the weight of diol and one-third the weight of polymerization inhibitor to the reactor according to the weight. Under the protection of inert gas, after the exothermic reaction is completed, raise the temperature of the reactor to 213℃~217℃ and keep it at the temperature until the acid value is 7mgKOH / g~11mgKOH / g.

[0018] (2) Cool down to 120°C, add maleic anhydride, one-third of the polymerization inhibitor and the remaining half of the diol to the reactor; after the exothermic reaction is over, raise the temperature of the reactor to 208°C~212°C and keep it at that temperature until the acid value is 15mgKOH / g~24mgKOH / g and the cone plate viscosity is 4000mPa·s~5000mPa·s;

[0019] (3) Cool down to 60°C, add styrene, photoinitiator and the remaining one-third of the polymerization inhibitor by weight to the reactor, and stir until uniform;

[0020] (4) Cool down to 30°C and add modified urea solution to the reactor according to the weight ratio to obtain modified urea solution thickened light-cured unsaturated polyester resin.

[0021] This preparation method achieves controllable preparation of resin molecular structure through stepwise polycondensation and precise temperature control. Step (1) uses high-temperature polycondensation to construct a rigid main chain of saturated acid / anhydride-diol, and the initial acid value control ensures the regularity of the main chain; Step (2) introduces maleic anhydride to form unsaturated sites, and secondary acid value and viscosity control optimize the molecular weight distribution of the prepolymer, providing a stable framework for the thickening network. The addition of staged polymerization inhibitors effectively suppresses side reactions and avoids the risk of gelation. The low-temperature mixing of styrene and photoinitiator maximizes the retention of the active component's effectiveness, and the final addition of modified urea solution utilizes its shear sensitivity to rapidly construct a uniform three-dimensional hydrogen bond network in a low-temperature, low-viscosity system, preventing filler sedimentation and maintaining the resin's high light transmittance. The inert gas protection and gradient cooling strategy throughout the process ensure the purity of the resin color and storage stability. The resulting product has high mechanical strength, excellent thixotropy, and ultraviolet light penetration depth, meeting the stringent requirements of CIPP thick-wall repair for material rheological properties and photocuring efficiency.

[0022] As a further aspect of the present invention, the heating rate in steps (1) and (2) is 12℃ / h to 18℃ / h. Controlling the heating rate ensures a smooth esterification reaction between the anhydride and the diol, avoiding localized overheating that could lead to chain breakage or cross-linking side reactions. This rate matches the kinetics of the polycondensation reaction, ensuring linear growth of the main chain and uniform molecular weight distribution, providing a well-organized framework for the subsequent thickening network, while maintaining precise control over the acid value, ensuring the synergistic optimization of resin transmittance and mechanical strength.

[0023] The modified urea solution used to thicken photocurable unsaturated polyester resin is preferably applied in the field of thickening and modification of photocurable unsaturated polyester resin.

[0024] Compared with the prior art, the beneficial effects of the modified urea solution thickening photocurable unsaturated polyester resin and its preparation method of the present invention are as follows: The present invention generates a three-dimensional network structure through modified urea solution, forming excellent thixotropy and fluidity, which can prevent sedimentation and improve anti-sagging performance; the synthesized resin has high mechanical strength and excellent thickening performance, and can replace magnesium oxide paste; it improves transparency and ultraviolet light penetration, shortens photocuring time, and is suitable for photocurable unsaturated polyester resin type thickeners, meeting the requirements of thick-walled CIPP. Detailed Implementation

[0025] Example 1

[0026] A modified urea solution-thickened, light-curable unsaturated polyester resin, the raw materials of which are composed of the following components in parts by weight:

[0027] 37 parts maleic anhydride

[0028] 47 parts of phthalic anhydride

[0029] 55 parts of a diol mixture of ethylene glycol, diethylene glycol and neopentyl glycol in a molar ratio of 1:1:1

[0030] 65 parts of styrene

[0031] RHEOBYK-410 2 copies

[0032] 0.8 parts of (2,4,6-trimethylbenzoyl)diphenylphosphine oxide

[0033] 0.08 parts of hydroquinone

[0034] 0.07 parts of triphenyl phosphite

[0035] 0.05 parts of a mixture of dibutyltin oxide and zinc acetate in a 1:1 mass ratio.

[0036] Preparation of modified urea solution-thickened photocurable unsaturated polyester resin:

[0037] (1) Add parts by weight of saturated diacid / anhydride, antioxidant and catalyst, half the weight of diol and one-third the weight of polymerization inhibitor to the reactor. Under inert gas protection, after the exothermic reaction is completed, raise the temperature of the reactor to 215°C and keep it at the temperature until the acid value is 9mgKOH / g.

[0038] (2) Cool down to 120°C, add maleic anhydride, one-third of the polymerization inhibitor and the remaining half of the diol to the reactor; after the heat release is completed, raise the temperature of the reactor to 210°C and keep it at the temperature until the acid value is 20 mg KOH / g and the cone plate viscosity is 4500 mPa·s.

[0039] (3) Cool down to 60°C, add styrene, photoinitiator and the remaining one-third of the polymerization inhibitor by weight to the reactor, and stir until uniform;

[0040] (4) Cool down to 30°C and add modified urea solution to the reactor according to the weight ratio to obtain modified urea solution thickened light-cured unsaturated polyester resin.

[0041] Example 2

[0042] A modified urea solution-thickened, light-curable unsaturated polyester resin, the raw materials of which are composed of the following components in parts by weight:

[0043] 31 parts maleic anhydride

[0044] 51 parts of isophthalic acid

[0045] 58 parts of a diol mixture of ethylene glycol and neopentyl glycol in a molar ratio of 1:1

[0046] 67 portions of styrene

[0047] RHEOBYK-410 4 copies

[0048] 0.65 parts of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide

[0049] 0.025 parts of p-benzoquinone

[0050] 0.07 parts of triphenyl phosphite

[0051] 0.05 parts zinc acetate

[0052] Preparation of modified urea solution-thickened photocurable unsaturated polyester resin:

[0053] (1) Add parts by weight of saturated diacid / anhydride, antioxidant and catalyst, half the weight of diol and one-third the weight of polymerization inhibitor to the reactor. Under inert gas protection, after the exothermic reaction is completed, raise the temperature of the reactor to 214°C and keep it at the temperature until the acid value is 8mgKOH / g.

[0054] (2) Cool down to 120°C, add maleic anhydride, one-third of the polymerization inhibitor and the remaining half of the diol to the reactor; after the heat release is completed, raise the temperature of the reactor to 209°C and keep it at the temperature until the acid value is 18 mg KOH / g and the cone plate viscosity is 4200 mPa·s.

[0055] (3) Cool down to 60°C, add styrene, photoinitiator and the remaining one-third of the polymerization inhibitor by weight to the reactor, and stir until uniform;

[0056] (4) Cool down to 30°C and add modified urea solution to the reactor according to the weight ratio to obtain modified urea solution thickened light-cured unsaturated polyester resin.

[0057] Example 3

[0058] A modified urea solution-thickened, light-curable unsaturated polyester resin, the raw materials of which are composed of the following components in parts by weight:

[0059] 33 parts maleic anhydride

[0060] 49 parts of terephthalic acid

[0061] 12 parts of propylene glycol

[0062] 12 parts ethylene glycol

[0063] 33 parts of neopentyl glycol

[0064] 66 portions of styrene

[0065] RHEOBYK-410 6 copies

[0066] 0.65 parts of ethyl 2,4,6-trimethylbenzoylphenylphosphonate

[0067] 0.025 parts of methylhydroquinone

[0068] 0.07 parts of 2,5-di-tert-butylhydroquinone

[0069] 0.05 parts of a mixture of dibutyltin oxide and zinc acetate in a mass ratio of 1:2

[0070] Preparation of modified urea solution-thickened photocurable unsaturated polyester resin:

[0071] (1) Add parts by weight of saturated diacid / anhydride, antioxidant and catalyst, half the weight of diol and one-third the weight of polymerization inhibitor to the reactor. Under inert gas protection, after the exothermic reaction is completed, raise the temperature of the reactor to 216°C and keep it at the temperature until the acid value is 10mgKOH / g.

[0072] (2) Cool down to 120°C, add maleic anhydride, one-third of the polymerization inhibitor and the remaining half of the diol to the reactor; after the heat release is completed, raise the temperature of the reactor to 211°C and keep it at the temperature until the acid value is 22 mg KOH / g and the cone plate viscosity is 4800 mPa·s.

[0073] (3) Cool down to 60°C, add styrene, photoinitiator and the remaining one-third of the polymerization inhibitor by weight to the reactor, and stir until uniform;

[0074] (4) Cool down to 30°C and add modified urea solution to the reactor according to the weight ratio to obtain modified urea solution thickened light-cured unsaturated polyester resin.

[0075] Example 4

[0076] A modified urea solution-thickened, light-curable unsaturated polyester resin, the raw materials of which are composed of the following components in parts by weight:

[0077] 35 parts maleic anhydride

[0078] 50 parts of a compound of phthalic anhydride and isophthalic acid in a molar ratio of 1:1

[0079] 61 parts of ethylene glycol

[0080] 62 parts of styrene

[0081] RHEOBYK-410 8 copies

[0082] 0.65 parts of 2-isopropylthioxanthone

[0083] 0.025 parts of tert-butylhydroquinone

[0084] Triphenyl phosphite 0.08 parts

[0085] 0.06 parts zinc acetate

[0086] Preparation of modified urea solution-thickened photocurable unsaturated polyester resin:

[0087] (1) Add parts by weight of saturated diacid / anhydride, antioxidant and catalyst, half the weight of diol and one-third the weight of polymerization inhibitor to the reactor. Under inert gas protection, after the exothermic reaction is completed, raise the temperature of the reactor to 213°C and keep it at the temperature until the acid value is 7mgKOH / g.

[0088] (2) Cool down to 120°C, add maleic anhydride, one-third of the polymerization inhibitor and the remaining half of the diol to the reactor; after the exothermic reaction is over, raise the temperature of the reactor to 208°C and keep it at that temperature until the acid value is 15 mg KOH / g and the cone plate viscosity is 4000 mPa·s.

[0089] (3) Cool down to 60°C, add styrene, photoinitiator and the remaining one-third of the polymerization inhibitor by weight to the reactor, and stir until uniform;

[0090] (4) Cool down to 30°C and add modified urea solution to the reactor according to the weight ratio to obtain modified urea solution thickened light-cured unsaturated polyester resin.

[0091] Example 5

[0092] A modified urea solution-thickened, light-curable unsaturated polyester resin, the raw materials of which are composed of the following components in parts by weight:

[0093] 29 parts maleic anhydride

[0094] 46 parts of terephthalic acid

[0095] 57 parts of neopentyl glycol

[0096] 68 portions of styrene

[0097] 7 parts of modified urea solution

[0098] 0.6 parts of phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide

[0099] 0.02 parts of p-benzoquinone

[0100] 0.06 parts of 2,5-di-tert-butylhydroquinone

[0101] 0.04 parts zinc acetate

[0102] Preparation of modified urea solution-thickened photocurable unsaturated polyester resin:

[0103] (1) Add parts by weight of saturated diacid / anhydride, antioxidant and catalyst, half the weight of diol and one-third the weight of polymerization inhibitor to the reactor. Under inert gas protection, after the exothermic reaction is completed, raise the temperature of the reactor to 217°C and keep it at the temperature until the acid value is 11 mgKOH / g.

[0104] (2) Cool down to 120°C, add maleic anhydride, one-third of the polymerization inhibitor and the remaining half of the diol to the reactor; after the heat release is completed, raise the temperature of the reactor to 212°C and keep it at the temperature until the acid value is 24 mgKOH / g and the cone plate viscosity is 4000mPa·s.

[0105] (3) Cool down to 60°C, add styrene, photoinitiator and the remaining one-third of the polymerization inhibitor by weight to the reactor, and stir until uniform;

[0106] (4) Cool down to 30°C and add modified urea solution to the reactor according to the weight ratio to obtain modified urea solution thickened light-cured unsaturated polyester resin.

[0107] Comparative Example 1

[0108] The unsaturated polyester resin in this comparative example is prepared using the same method as in the examples, except that the modified urea solution is replaced with WL-3035 magnesium oxide paste.

[0109] The unsaturated polyester resin raw material in this comparative example is composed of the following components in parts by weight:

[0110] 33 parts maleic anhydride

[0111] 49 parts of saturated dicarboxylic acid / anhydride

[0112] 56 parts of diol

[0113] 66 portions of styrene

[0114] 4 portions of WL-3035 magnesium oxide paste

[0115] 0.8 parts of (2,4,6-trimethylbenzoyl)diphenylphosphine oxide

[0116] 0.08 parts of hydroquinone

[0117] 0.07 parts of triphenyl phosphite

[0118] 0.05 parts of a mixture of dibutyltin oxide and zinc acetate in a 1:1 mass ratio.

[0119] The preparation method is the same as in Example 3.

[0120] Comparative Example 2

[0121] The unsaturated polyester resin in this comparative example is prepared using the same method as in the examples, except that no modified urea solution is added in this comparative example.

[0122] The unsaturated polyester resin raw material in this comparative example is composed of the following components in parts by weight:

[0123] 33 parts maleic anhydride

[0124] 49 parts of saturated dicarboxylic acid / anhydride

[0125] 56 parts of diol

[0126] 66 portions of styrene

[0127] 0.8 parts of (2,4,6-trimethylbenzoyl)diphenylphosphine oxide

[0128] 0.08 parts of hydroquinone

[0129] 0.07 parts of triphenyl phosphite

[0130] 0.05 parts of a mixture of dibutyltin oxide and zinc acetate in a 1:1 mass ratio.

[0131] The preparation method is the same as in Example 3.

[0132] Table 1 shows some properties of the unsaturated polyester resins described in Examples 1-5 and Comparative Examples 1-2, as shown in Table 1 below:

[0133] Table 1. Some properties of unsaturated polyester resins

[0134] .

[0135] Table 2 shows the thickening properties of the unsaturated polyester resins in Examples 1-5 and Comparative Examples 1-2, as shown in Table 2 below:

[0136] Table 2 Thickening properties of unsaturated polyester resins

[0137] .

[0138] As can be seen from the test results of Examples 1-5 and Comparative Examples 1-2 in Tables 1 and 2, the resin synthesized by the preparation method of the present invention has high mechanical strength; excellent thickening properties, can replace magnesium oxide paste; improves transparency and ultraviolet light penetration, shortens photocuring time, and meets the requirements of thick-walled CIPP.

[0139] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A modified urea solution-thickened, light-cured unsaturated polyester resin, characterized in that, The raw materials, by weight, consist of: 29-37 parts maleic anhydride, 46-51 parts saturated diacid / anhydride, 55-61 parts diol, 62-68 parts styrene, 2-8 parts modified urea solution, 0.6-0.8 parts photoinitiator, 0.02-0.08 parts polymerization inhibitor, 0.06-0.08 parts antioxidant, and 0.04-0.06 parts catalyst. The saturated dicarboxylic acid / anhydride is one or more of phthalic anhydride, isophthalic acid, and terephthalic acid; the modified urea solution is RHEOBYK-410.

2. The modified urea solution-thickened, light-cured unsaturated polyester resin according to claim 1, characterized in that: The diol is one or more of propylene glycol, ethylene glycol, diethylene glycol, and neopentyl glycol.

3. The modified urea solution-thickened, light-cured unsaturated polyester resin according to claim 1, characterized in that: The photoinitiator is one or more of (2,4,6-trimethylbenzoyl)diphenylphosphine oxide, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, ethyl 2,4,6-trimethylbenzoylphenylphosphonate, 2-isopropylthioxanthone, and 2-hydroxy-2-methylphenylpropane-1-one.

4. The modified urea solution-thickened, light-cured unsaturated polyester resin according to claim 1, characterized in that: The polymerization inhibitor is one or more of hydroquinone, p-benzoquinone, methylhydroquinone, or tert-butylhydroquinone.

5. The modified urea solution-thickened, light-cured unsaturated polyester resin according to claim 1, characterized in that: The antioxidant is triphenyl phosphite or 2,5-di-tert-butylhydroquinone.

6. The modified urea solution-thickened, light-cured unsaturated polyester resin according to claim 1, characterized in that: The catalyst is zinc acetate, or a mixture of dibutyltin oxide and zinc acetate.

7. A method for preparing the modified urea solution-thickened, light-cured unsaturated polyester resin according to any one of claims 1 to 6, characterized in that, The preparation steps include: 1) Add saturated diacid / anhydride, antioxidant, catalyst, half the weight of diol and one-third the weight of polymerization inhibitor to the reactor according to the weight parts. Under the protection of inert gas, after the exothermic reaction is completed, raise the temperature of the reactor to 213℃~217℃ and keep it at the temperature until the acid value reaches 7mgKOH / g~11mgKOH / g. 2) Cool down to 120℃, add maleic anhydride, one-third of the polymerization inhibitor and the remaining half of the diol by weight to the reactor; after the exothermic reaction is over, raise the temperature of the reactor to 208℃~212℃ and keep it at that temperature until the acid value reaches 15mgKOH / g~24mgKOH / g and the cone-plate viscosity reaches 4000mPa·s~5000mPa·s; 3) Cool down to 60°C, add the styrene, photoinitiator and the remaining one-third of the polymerization inhibitor by weight to the reactor, and stir until homogeneous; 4) Cool down to 30°C and add modified urea solution to the reactor according to the weight ratio to obtain modified urea solution thickened light-cured unsaturated polyester resin.

8. The method for preparing a modified urea solution-thickened, light-curable unsaturated polyester resin according to claim 7, characterized in that: The heating rate described in steps 1) and 2) is 12℃ / h to 18℃ / h.