An unsaturated polyester resin with low styrene volatility and a method for preparing the same

Abstract

The application relates to an unsaturated polyester resin with low styrene volatility and a preparation method thereof, and belongs to the technical field of unsaturated polyester resins. The unsaturated polyester resin with low styrene volatility is composed of the following components: unsaturated polyester resin, sodium octenyl succinate starch, composite lignin sulfonate, pine bark polyphenol, vanillic acid and styrene. The composite lignin sulfonate is composed of calcium lignosulfonate and sodium lignosulfonate in a weight ratio of 1.93-1.95:1. The preparation steps are as follows: 1) respectively weighing and drying calcium lignosulfonate and sodium lignosulfonate and sieving; 2) respectively weighing and drying pine bark polyphenol and vanillic acid; 3) adding sodium octenyl succinate starch, pine bark polyphenol, vanillic acid into the unsaturated polyester resin to mix, adding calcium lignosulfonate to mix, adding sodium lignosulfonate to mix, and then adding styrene to mix to obtain the unsaturated polyester resin with low styrene volatility. The unsaturated polyester resin with low styrene volatility has the characteristics of good inhibition effect and low cost.

Description

Technical Field

[0001] This invention belongs to the field of unsaturated polyester resin technology, specifically relating to an unsaturated polyester resin with low styrene volatility and its preparation method. Background Technology

[0002] Styrene plays an important role as both a crosslinking agent and a diluent in unsaturated polyester resins. Its high reactivity ensures fast resin curing speed and high crosslinking density. An appropriate addition ratio gives the resin excellent mechanical properties. Furthermore, due to its lower cost, being cheaper than the monomer methyl methacrylate, styrene remains the most commonly used monomer in unsaturated polyester resins.

[0003] However, styrene is highly volatile, with a low vapor pressure at room temperature. During construction, its volatility reaches 30-50%, affecting resin cross-linking and curing, reducing mechanical properties, increasing viscosity, and altering gelation time, leading to raw material waste and economic losses. Furthermore, styrene poses significant health risks; it has a pungent odor, is highly irritating to mucous membranes, and prolonged exposure can damage the nervous system.

[0004] For example, resin-based artificial stone is a commonly used material in interior decoration. During the production, cutting, and installation of the stone, a large amount of styrene is released. Even long after the interior decoration is completed, styrene continues to volatilize, affecting the performance of the boards and harming human health. However, reducing the volatility of styrene has always been a major challenge for the industry.

[0005] Existing technologies for inhibiting styrene volatility, such as physical barrier materials and commercially available inhibitors, while offering good styrene inhibition effects, are expensive and complex to manufacture. Currently developed bio-based monomer alternatives are costly and have poor performance. Film-forming agent technology, which uses compounded paraffins and modified waxes to form a barrier layer on the resin surface to inhibit styrene volatilization, is still relatively ineffective. Therefore, the market urgently needs to develop a competitive unsaturated polyester resin with low styrene volatility.

[0006] A Chinese invention patent entitled "A Styrene Volatilization Inhibitor and Its Application" (publication number CN109535720A) describes a method that uses the synergistic effect of three components to inhibit the volatilization of styrene in unsaturated polyester resin and marble adhesive without reducing mechanical strength. However, the hollow nanospheres need to be modified before use, resulting in higher costs. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a low-styrene-volatility unsaturated polyester resin and its preparation method. The low-styrene-volatility unsaturated polyester resin of the present invention has the characteristics of good inhibition effect and low cost.

[0008] To achieve the above objectives, the present invention provides a low-styrene-volatile unsaturated polyester resin, comprising, by weight, the following components: 115-119 parts unsaturated polyester resin, 1.60-3.12 parts sodium octenyl succinate starch, 0.5-1.05 parts composite lignin sulfonate, 0.113-0.312 parts pine bark polyphenols, 0.038-0.104 parts vanillic acid, and 22-32 parts styrene; the composite lignin sulfonate is composed of calcium lignin sulfonate and sodium lignin sulfonate in a weight ratio of 1.93-1.95:1. Except for the unsaturated polyester resin and styrene, the other components (sodium octenyl succinate starch, composite lignin sulfonate, pine bark polyphenols, and vanillic acid) are all inhibitors.

[0009] The unsaturated polyester resin is an orthophthalic or bicyclic unsaturated polyester resin. Preferably, at 25°C, the orthophthalic unsaturated polyester resin has a viscosity of 230~480 mPa·s; an acid value of 18~26 mgKOH / g; a gel time of 12~15 min; and a solid content of 60~66%.

[0010] Preferably, the composition includes 116 parts of unsaturated polyester resin, 2.10 parts of sodium octenyl succinate starch, 0.469 parts of calcium lignosulfonate, 0.241 parts of sodium lignosulfonate, 0.210 parts of pine bark polyphenols, 0.070 parts of vanillic acid, and 32 parts of styrene.

[0011] The phenolic hydroxyl groups of calcium lignosulfonate can form intermolecular hydrogen bonds with the benzene rings of styrene, reducing the concentration of free styrene molecules. Sodium lignosulfonate can undergo π-π adsorption with styrene, and the phenolic hydroxyl groups can also participate in resin cross-linking reactions, enhancing mechanical properties and corrosion resistance. There is also a good synergistic effect between the two: calcium lignosulfonate can improve the interfacial bonding force with fillers, enhancing crack resistance and strength, thus compensating for the mechanical property deficiencies of sodium lignosulfonate. Sodium lignosulfonate can improve dispersibility, further enhancing interfacial bonding force, and also prevents the aggregation of calcium lignosulfonate, helping to maintain performance stability. The above ratio achieves the optimal styrene suppression effect and overall performance. Calcium ions can form a relatively stable electrostatic-ionic double network with sodium octenyl succinate starch, and the synergistic effect between the components can more effectively and stably block styrene volatilization.

[0012] The weight ratio of pine bark polyphenols to vanillic acid is 2.9~3.0:1; the difference in molecular structure between pine bark polyphenols and vanillic acid can form a complementary adsorption network, further reducing the volatilization of styrene and improving the UV aging resistance of the resin after curing.

[0013] The weight ratio of sodium octenyl succinate starch, composite lignin sulfonate, pine bark polyphenols, and vanillic acid is 20.0~55.2:7.1~18.6:2.9~3.0:1. Insufficient sodium octenyl succinate starch will result in incomplete film formation and reduced inhibition rate; insufficient pine bark polyphenols and vanillic acid will reduce the density of the barrier interface layer; excessive composite lignin sulfonate will lead to excessive increase in resin viscosity, while insufficient composite lignin sulfonate will affect the synergistic effect.

[0014] The total weight of sodium octenyl succinate starch, pine bark polyphenols, vanillic acid, and composite lignin sulfonate accounts for 2.2% to 3.9% of the weight of the unsaturated polyester resin. Within this range, the synergistic effect of the four components can be fully utilized, effectively inhibiting styrene volatilization through multiple mechanisms such as film-forming barrier, molecular adsorption, and chemical bonding. At the same time, hydrogen bonding, π-π adsorption, and ion bridging between components fill interfacial defects, improving the mechanical strength and aging resistance of the resin, and avoiding the problem of insufficient inhibition effect caused by abnormal resin viscosity due to excessively high component proportions or excessively low component proportions.

[0015] Preferably, the total weight of sodium octenyl succinate starch, pine bark polyphenols, vanillic acid, and composite lignin sulfonate accounts for 2.4-2.7% of the weight of the unsaturated polyester resin. The phenolic hydroxyl groups in the composite lignin sulfonate react with the resin to crosslink and enhance the intermolecular bonding force; sodium octenyl succinate starch fills interfacial defects through calcium ion bridging, improving crack resistance. The four components not only do not affect mechanical properties, but also enhance the strength of the resin matrix through synergistic effects, solving the problem of traditional methods that suppress volatilization but reduce mechanical properties.

[0016] Sodium octenyl succinate starch exhibits amphiphilic properties. Its hydrophobic alkyl chains connect to the resin, while its hydrophilic ends migrate to the surface to form a tight insulating film, blocking the volatilization pathway of styrene. Sodium octenyl succinate starch can also generate van der Waals forces with styrene molecules, thereby reducing the concentration of free styrene molecules. Compared to traditional paraffin-based film-forming agents, the polysaccharide skeleton of sodium octenyl succinate starch has better heat resistance than alkane chains and produces a higher film density. It blocks styrene volatilization through both film-forming barrier and molecular fixation. Sodium octenyl succinate starch also reduces the volume shrinkage rate of the resin and possesses good environmental and biodegradable properties. The relatively large particle size of sodium octenyl succinate starch (20-50 μm) enhances the skeletal support. Furthermore, the bridging effect of calcium ions and the filling of gaps by small calcium lignin sulfonate particles reduce interfacial defects. The synergistic effect of these components not only improves the stability of the system but also significantly inhibits styrene diffusion.

[0017] This invention also provides a method for preparing an unsaturated polyester resin with low styrene volatility, comprising the following steps:

[0018] (1) Weigh calcium lignosulfonate and sodium lignosulfonate separately by weight, dry them, and then sieve them;

[0019] (2) Weigh out the pine bark polyphenols and vanillic acid by weight and dry them separately;

[0020] (3) Mix sodium octenyl succinate starch, pine bark polyphenols, vanillic acid and unsaturated polyester resin, add calcium lignosulfonate and mix, add sodium lignosulfonate and mix, add styrene and mix; to obtain unsaturated polyester resin with low styrene volatility.

[0021] The specific operation of step (1) is to weigh calcium lignosulfonate and sodium lignosulfonate according to their weight parts, dry them at 55~65℃ under vacuum for 2.8~3.2h, and then pulverize them through a 200-mesh sieve. The vacuum degree is -0.07~0.09MPa, preferably -0.08MPa.

[0022] The specific operation of step (2) is to weigh pine bark polyphenols and vanillic acid according to their weight, heat them to 95-105℃ at a rate of 6-8℃ / min, and dry them for 1.8-2.2h; then heat them to 135-145℃ at a rate of 4-6℃ / min and dry them for 0.8-1.2h.

[0023] The specific operation of step (3) is as follows: add sodium octenyl succinate starch, pine bark polyphenols, and vanillic acid to the unsaturated polyester resin and shear at 1000-2000 rpm for 10-20 min for homogenization; add calcium lignosulfonate and shear at 1000-2000 rpm for 10-20 min for homogenization; add sodium lignosulfonate and shear at 1000-2000 rpm for 10-20 min for homogenization; then add styrene and shear at 500-1000 rpm for 10-20 min for homogenization; and obtain an unsaturated polyester resin with low styrene volatility.

[0024] Calcium ions in calcium lignosulfonate are a key component in forming a stable system. They can form a robust electrostatic-ionic double network with sodium octenyl succinate, laying the foundation for inhibiting styrene volatilization and enhancing resin performance. Adding calcium lignosulfonate first, followed by sodium lignosulfonate, allows calcium ions to preferentially and fully complex with sodium octenyl succinate in the system, unaffected by other components, ensuring the complete formation of the double network structure. The subsequently added sodium lignosulfonate effectively disperses calcium lignosulfonate, preventing agglomeration and further optimizing system stability, achieving a synergistic effect. Adding sodium lignosulfonate first causes its molecules to prematurely occupy the interaction sites in the system, interfering with the complexation process between calcium ions and sodium octenyl succinate. This prevents the stable formation of the electrostatic-ionic double network structure, weakening the styrene-inhibiting effect and affecting the resin's mechanical properties and interfacial bonding.

[0025] According to another aspect of the present invention, the present invention also provides the application of the above-described low-styrene-volatility unsaturated polyester resin or the low-styrene-volatility unsaturated polyester resin prepared by the above-described preparation method in the field of interior decoration.

[0026] Compared with the prior art, the beneficial effects of this invention are:

[0027] 1. The low-styrene-volatile unsaturated polyester resin of the present invention has the characteristics of good inhibition effect and low cost. The present invention achieves a high inhibition rate of styrene by adding sodium octenyl succinate starch, pine bark polyphenols, vanillic acid, and composite lignin sulfonate, with the synergistic effect of several components. This improves the safety of construction workers and users during construction and product use, and reduces raw material loss costs. The unsaturated polyester resin of the present invention exhibits a weight change of 0.3528~0.6902g after 12 hours of storage at room temperature, 0.803~1.210g after 24 hours, 1.080~1.699g after 36 hours, and a weight change of 0.884~1.710g upon curing. The casting of this invention exhibits a tensile strength of 70-77 MPa, a tensile modulus of elasticity of 3402-3551 MPa, an elongation at break of 4.33-4.71%, a flexural strength of 115-125 MPa, a flexural modulus of elasticity of 3910-4125 MPa, and an impact strength of 11.95-13.49 kJ / m. 2 The heat distortion temperature reaches 75~79℃, and the Barcol hardness reaches 35~37HBa.

[0028] 2. In the preparation method of the low styrene volatility unsaturated polyester resin of the present invention, calcium lignosulfonate is added first and then sodium lignosulfonate. Calcium ions can preferentially and fully complex with sodium octenyl succinate starch in the system without interference from other components, ensuring the complete formation of the double network structure. The sodium lignosulfonate added later can fully exert its dispersing effect, prevent the aggregation of calcium lignosulfonate, further optimize the stability of the system, and achieve synergistic effect between the two.

[0029] 3. The present invention has low cost, simple preparation process, and the mechanical strength of the cast body of the low styrene volatility unsaturated polyester resin and downstream products is not reduced. Detailed Implementation

[0030] Example 3 is the preferred embodiment of the present invention. The present invention will be further described below with reference to specific embodiments and comparative examples.

[0031] The chemical additives used in the embodiments and comparative examples of this invention are all commercially available, and the specific information is as follows:

[0032] Phthalic unsaturated polyester resin: viscosity at 25℃ is 230~480mPa·S; acid value is 18~26mgKOH / g; gel time is 12~15min; solid content is 60~66%; purchased from Shandong Wanglin New Materials Co., Ltd.

[0033] Styrene: Purchased from Zhangjiagang Free Trade Zone Aolide International Trade Co., Ltd.;

[0034] Sodium lignosulfonate: purchased from Weihui branch of Shandong Enlin Biotechnology Co., Ltd.

[0035] Calcium lignosulfonate: purchased from Weihui branch of Shandong Enlin Biotechnology Co., Ltd.

[0036] Pine bark polyphenols: purchased from Anhui Qijun Food Ingredients Co., Ltd.;

[0037] Sodium octenyl succinate starch, type A: purchased from Zhengzhou Yuxing Food Additives Co., Ltd.

[0038] Vanillic acid: purchased from Hefei Kinu Biotechnology Co., Ltd.;

[0039] Cobalt isooctanoate: purchased from Shanghai Taoyuan Cobalt Co., Ltd.;

[0040] Methyl ethyl ketone peroxide: purchased from Qingdao Feiyang Trading Co., Ltd.

[0041] Table 1. Raw material formulations used in the examples (by weight).

[0042] .

[0043] Example 1

[0044] The preparation method in this embodiment adopts the following steps:

[0045] (1) Weigh calcium lignosulfonate and sodium lignosulfonate by weight, dry them under vacuum at 55°C for 3.2 hours, and then pulverize them through a 200-mesh sieve.

[0046] (2) Weigh out pine bark polyphenols and vanillic acid by weight, heat them to 95°C at a rate of 6°C / min, and dry them for 2.2 hours; then heat them to 135°C at a rate of 4°C / min and dry them for 1.2 hours.

[0047] (3) Add sodium octenyl succinate starch, pine bark polyphenols, and vanillic acid to unsaturated polyester resin and homogenize by high-speed shearing at 1200 rpm for 20 min. Add calcium lignosulfonate and homogenize by high-speed shearing at 1500 rpm for 10 min. Add sodium lignosulfonate and homogenize by high-speed shearing at 1500 rpm for 15 min. Then add styrene and homogenize by high-speed shearing at 500 rpm for 20 min. The unsaturated polyester resin is an orthophthalic unsaturated polyester resin. A low styrene volatility unsaturated polyester resin is obtained.

[0048] Example 2

[0049] The preparation method in this embodiment adopts the following steps:

[0050] (1) Weigh calcium lignosulfonate and sodium lignosulfonate by weight, dry them under vacuum at 65°C for 2.8 h, and then pulverize them through a 200-mesh sieve;

[0051] (2) Weigh out pine bark polyphenols and vanillic acid by weight, heat them to 105°C at a rate of 8°C / min, and dry them for 1.8h; then heat them to 145°C at a rate of 6°C / min and dry them for 0.8h.

[0052] (3) Add sodium octenyl succinate starch, pine bark polyphenols, and vanillic acid to unsaturated polyester resin and homogenize by high-speed shearing at 1500 rpm for 15 min. Add calcium lignosulfonate and homogenize by high-speed shearing at 1500 rpm for 15 min. Add sodium lignosulfonate and homogenize by high-speed shearing at 1500 rpm for 20 min. Add styrene and homogenize by high-speed shearing at 1000 rpm for 10 min. The unsaturated polyester resin is phthalic unsaturated polyester resin. Obtain unsaturated polyester resin with low styrene volatility.

[0053] Example 3

[0054] The preparation method in this embodiment adopts the following steps:

[0055] (1) Weigh calcium lignosulfonate and sodium lignosulfonate by weight, dry them under vacuum at 60°C for 3 hours, and then pulverize them through a 200-mesh sieve.

[0056] (2) Weigh out pine bark polyphenols and vanillic acid by weight, heat them to 100°C at a rate of 7°C / min, and dry them for 2 hours; then heat them to 140°C at a rate of 5°C / min and dry them for 1 hour.

[0057] (3) Add sodium octenyl succinate starch, pine bark polyphenols, and vanillic acid to unsaturated polyester resin and homogenize by high-speed shearing at 1500 rpm for 15 min. Add calcium lignosulfonate and homogenize by high-speed shearing at 1500 rpm for 15 min. Add sodium lignosulfonate and homogenize by high-speed shearing at 1500 rpm for 20 min. Add styrene and homogenize by high-speed shearing at 700 rpm for 15 min. The unsaturated polyester resin is phthalic unsaturated polyester resin. A low styrene volatility unsaturated polyester resin is obtained.

[0058] Example 4

[0059] The preparation method in this embodiment adopts the following steps:

[0060] (1) Weigh calcium lignosulfonate and sodium lignosulfonate by weight, dry them under vacuum at 60°C for 3 hours, and then pulverize them through a 200-mesh sieve.

[0061] (2) Weigh out pine bark polyphenols and vanillic acid by weight, heat them to 100°C at a rate of 7°C / min, and dry them for 2 hours; then heat them to 140°C at a rate of 5°C / min and dry them for 1 hour.

[0062] (3) Add sodium octenyl succinate starch, pine bark polyphenols, and vanillic acid to unsaturated polyester resin and homogenize by high-speed shearing at 1600 rpm for 15 min. Add calcium lignosulfonate and homogenize by high-speed shearing at 1650 rpm for 20 min. Add sodium lignosulfonate and homogenize by high-speed shearing at 1600 rpm for 20 min. Add styrene and homogenize by high-speed shearing at 700 rpm for 15 min. The unsaturated polyester resin is phthalic unsaturated polyester resin. A low styrene volatility unsaturated polyester resin is obtained.

[0063] Example 5

[0064] The preparation method in this embodiment adopts the following steps:

[0065] (1) Weigh calcium lignosulfonate and sodium lignosulfonate by weight, dry them under vacuum at 60°C for 3 hours, and then pulverize them through a 200-mesh sieve.

[0066] (2) Weigh out pine bark polyphenols and vanillic acid by weight, heat them to 100°C at a rate of 7°C / min, and dry them for 2 hours; then heat them to 140°C at a rate of 5°C / min and dry them for 1 hour.

[0067] (3) Add sodium octenyl succinate starch, pine bark polyphenols, and vanillic acid to unsaturated polyester resin and homogenize by high-speed shearing at 1600 rpm for 15 min. Add calcium lignosulfonate and homogenize by high-speed shearing at 1650 rpm for 20 min. Add sodium lignosulfonate and homogenize by high-speed shearing at 1600 rpm for 20 min. Add styrene and homogenize by high-speed shearing at 700 rpm for 15 min. The unsaturated polyester resin is an orthophthalic unsaturated polyester resin. A low-styrene volatility unsaturated polyester resin is obtained.

[0068] Comparative Example 1

[0069] The preparation method of the low styrene volatility unsaturated polyester resin described in this comparative example is the same as that in Example 3, except that pine bark polyphenols, vanillic acid and composite lignin sulfonate are not added in step (3).

[0070] Comparative Example 2

[0071] The preparation method of the low styrene volatility unsaturated polyester resin described in this comparative example is the same as that in Example 3, except that sodium octenyl succinate starch, pine bark polyphenols and vanillic acid are not added in step (3).

[0072] Comparative Example 3

[0073] The preparation method of the low styrene volatility unsaturated polyester resin described in this comparative example is the same as that in Example 3, except that pine bark polyphenols and vanillic acid are not added in step (3).

[0074] Comparative Example 4

[0075] The preparation method of the low styrene volatility unsaturated polyester resin described in this comparative example is the same as that in Example 3, except that sodium octenyl succinate starch and composite lignin sulfonate are not added in step (3).

[0076] Comparative Example 5

[0077] The raw material formulation of the low styrene volatility unsaturated polyester resin described in this comparative example is the same as that in Example 3, except that the rotation speed in step (3) is 700 rpm.

[0078] Preparation method of step (3): Add sodium octenyl succinate starch, pine bark polyphenols and vanillic acid to unsaturated polyester resin and homogenize by high-speed shearing at 700 rpm for 20 min. Add calcium lignosulfonate and homogenize by high-speed shearing at 700 rpm for 20 min. Then add sodium lignosulfonate and homogenize by high-speed shearing at 700 rpm for 20 min. Obtain unsaturated polyester resin with low styrene volatility.

[0079] Comparative Example 6

[0080] The raw material formulation of the low styrene volatility unsaturated polyester resin described in this comparative example is the same as that in Example 3, except that all raw materials are added together in step (3).

[0081] Preparation method of step (3): Sodium octenyl succinate starch, pine bark polyphenols, vanillic acid, unsaturated polyester resin, calcium lignosulfonate, and sodium lignosulfonate are mixed and homogenized by high-speed shearing at 1500 rpm for 20 min to obtain unsaturated polyester resin with low styrene volatility.

[0082] Comparative Example 7

[0083] The preparation method of the low styrene volatility unsaturated polyester resin described in this comparative example is the same as that in Example 3, except that 0.182 parts of pine bark polyphenols and 0.098 parts of vanillic acid are added in step (3).

[0084] Comparative Example 8

[0085] The raw material formulation of the low-styrene-volatile unsaturated polyester resin described in this comparative example is the same as that in Example 3, the only difference being that...

[0086] (1) Weigh calcium lignosulfonate and sodium lignosulfonate by weight, dry them under vacuum at 60°C for 3 hours, and then pulverize them through a 200-mesh sieve.

[0087] (2) Weigh out pine bark polyphenols and vanillic acid by weight and dry them at 150°C for 3 hours.

[0088] Comparative Example 9

[0089] The preparation method of this comparative example is the same as that of Example 3. This comparative example is an unsaturated polyester resin without the addition of any inhibitors.

[0090] Comparative Example 10

[0091] The raw material formulation of the low styrene volatility unsaturated polyester resin described in this comparative example is the same as that in Example 3, the only difference is that sodium lignosulfonate is added first in step (3), followed by calcium lignosulfonate.

[0092] Preparation method of step (3):

[0093] Sodium octenyl succinate starch, pine bark polyphenols, and vanillic acid were added to unsaturated polyester resin and homogenized by high-speed shearing at 1500 rpm for 15 min. Sodium lignosulfonate was added and homogenized by high-speed shearing at 1500 rpm for 15 min. Calcium lignosulfonate was added and homogenized by high-speed shearing at 1500 rpm for 20 min. Styrene was then added and homogenized by high-speed shearing at 700 rpm for 15 min. This yielded an unsaturated polyester resin with low styrene volatility.

[0094] Comparative Example 11

[0095] The raw material formulation of the low styrene volatility unsaturated polyester resin described in this comparative example is the same as that in Example 3, except that calcium lignosulfonate and sodium lignosulfonate are added simultaneously in step (3).

[0096] Preparation method of step (3):

[0097] Sodium octenyl succinate starch, pine bark polyphenols, and vanillic acid were added to unsaturated polyester resin and homogenized by high-speed shearing at 1500 rpm for 15 min. Sodium lignosulfonate and calcium lignosulfonate were added and homogenized by high-speed shearing at 1500 rpm for 20 min. Styrene was then added and homogenized by high-speed shearing at 700 rpm for 15 min. This yielded an unsaturated polyester resin with low styrene volatility.

[0098] Performance testing

[0099] The unsaturated polyester resins prepared in the examples and comparative examples were subjected to performance tests, and the specific test results are shown in Tables 2 and 3.

[0100] Specific methods for testing the styrene volatilization rate of unsaturated polyester resin during normal storage and curing:

[0101] I. Styrene volatility test method at room temperature (24~26℃): Place 100g of low styrene volatility unsaturated polyester resin in a transparent glass petri dish and place it in an environment of 24~26℃. Weigh it again every 12 hours and calculate the amount of styrene volatilization.

[0102] II. Styrene Volatility Test Method During Curing: Pour 100g of low-volatility unsaturated polyester resin into a transparent glass petri dish, add the accelerator and curing agent, stir evenly, weigh after curing, and calculate the styrene volatilization amount. The accelerator is cobalt isooctanoate, added at 0.16% of the weight of the low-volatility unsaturated polyester resin; the curing agent is methyl ethyl ketone peroxide, added at 1.5% of the weight of the unsaturated polyester resin.

[0103] The preparation of the casting shall be in accordance with GB / T2567-2021;

[0104] Tensile strength was tested in accordance with GB / T2567-2021;

[0105] The tensile modulus of elasticity was tested in accordance with GB / T2567-2021;

[0106] The elongation at break was tested in accordance with GB / T2567-2021;

[0107] Bending strength was tested in accordance with GB / T2567-2021;

[0108] The flexural modulus of elasticity was tested in accordance with GB / T2567-2021;

[0109] Impact strength was tested in accordance with GB / T2567-2021;

[0110] The heat distortion temperature was tested in accordance with GB / T1634.2-2019;

[0111] The Barcol hardness was tested according to GB / T3854-2017.

[0112] Table 2. Results of styrene volatility tests in Examples 1-5 and Comparative Examples 1-11

[0113] .

[0114] Table 3 shows the performance test results of the castings from Examples 1-5 and Comparative Example 9.

[0115]

[0116] Table 2 shows the styrene volatility test results. The weight change of this invention after 12 hours of storage at room temperature is 0.3528~0.6902 g; after 24 hours, it is 0.803~1.210 g; after 36 hours, it is 1.080~1.699 g; and upon curing, it is 0.884~1.710 g. Table 3 shows the performance test results of the casting. The casting of this invention has a tensile strength of 70~77 MPa, a tensile modulus of elasticity of 3402~3551 MPa, an elongation at break of 4.33~4.71%, a flexural strength of 115~125 MPa, a flexural modulus of elasticity of 3910~4125 MPa, and an impact strength of 11.95~13.49 kJ / m². 2 Heat distortion temperature 75~79℃, Barcol hardness 35~37HBa.

[0117] Comparative Example 1: The lack of pine bark polyphenols, vanillic acid, and complex lignin sulfonate led to an increase in styrene volatilization. Comparative Example 2: The lack of sodium octenyl succinate starch, pine bark polyphenols, and vanillic acid led to an increase in styrene volatilization. Comparative Example 3: The lack of pine bark polyphenols and vanillic acid prevented the formation of a complementary adsorption network, resulting in increased styrene volatilization. Comparative Example 4: The lack of sodium octenyl succinate starch and complex lignin sulfonate led to increased styrene volatilization. Comparative Example 5: The shear speed exceeded the range of this application, resulting in uneven component mixing and a decreased synergistic inhibition effect, leading to increased styrene volatilization. Comparative Example 6: Simple mixing led to increased styrene volatilization. Comparative Example 7: The ratio of pine bark polyphenols and vanillic acid exceeded the range of this application, leading to increased styrene volatilization. Comparative Example 8: The drying process exceeded the range of this application; excessive drying destroyed component activity, leading to increased styrene volatilization. Example 3 has the optimal formulation and process; changes in formulation and process exceeding the range of this application resulted in a decrease in the styrene inhibition effect.

[0118] This invention effectively inhibits styrene volatilization by adding sodium octenyl succinate starch, pine bark polyphenols, vanillic acid, and a complex lignin sulfonate. Compared with Comparative Example 9, Example 3 achieved a styrene inhibition rate of 82% after 12 hours. Comparative Example 10 altered the order of addition of calcium lignin sulfonate and sodium lignin sulfonate, disrupting their synergistic effect. This affected the formation of a stable network between calcium lignin sulfonate and calcium ions, and also reduced the dispersing effect of sodium lignin sulfonate, leading to uneven component mixing and increased styrene volatilization. Comparative Example 11 added calcium lignin sulfonate and sodium lignin sulfonate simultaneously, disrupting their synergistic effect. This prevented calcium lignin sulfonate from fully forming a stable network and weakened the dispersing and anti-agglomeration effect of sodium lignin sulfonate, resulting in uneven component mixing, decreased interfacial bonding, and increased styrene volatilization. The test results of Comparative Examples 1-4 show the synergistic inhibitory effect among sodium octenyl succinate starch, pine bark polyphenols, vanillic acid, and composite lignin sulfonate; the test results of the Examples show that the inhibitory components enhance the mechanical properties of the resin.

[0119] 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 low-styrene-volatile unsaturated polyester resin, characterized in that, The product, by weight, comprises the following components: 115-119 parts unsaturated polyester resin, 1.60-3.12 parts sodium octenyl succinate starch, 0.5-1.05 parts composite lignin sulfonate, 0.113-0.312 parts pine bark polyphenols, 0.038-0.104 parts vanillic acid, and 22-32 parts styrene; the composite lignin sulfonate is composed of calcium lignin sulfonate and sodium lignin sulfonate in a weight ratio of 1.93-1.95:1; the weight ratio of pine bark polyphenols to vanillic acid is 2.9-3.0:

1. The method for preparing the low-styrene-volatile unsaturated polyester resin includes the following steps: (1) Weigh calcium lignosulfonate and sodium lignosulfonate separately by weight, dry them, and then sieve them; (2) Weigh out pine bark polyphenols and vanillic acid by weight, heat them to 95-105℃ at a rate of 6-8℃ / min, and dry them for 1.8-2.2h; then heat them to 135-145℃ at a rate of 4-6℃ / min and dry them for 0.8-1.2h. (3) Add sodium octenyl succinate starch, pine bark polyphenols and vanillic acid to unsaturated polyester resin and mix at high speed of 1200~1600 rpm for 10~20 min. Add calcium lignosulfonate and mix at high speed of 1500~1650 rpm for 10~20 min. Add sodium lignosulfonate and mix at high speed of 1500~1600 rpm for 15~20 min. Then add styrene and mix at high speed of 500~1000 rpm for 10~20 min to obtain unsaturated polyester resin with low styrene volatility.

2. The low-styrene-volatility unsaturated polyester resin according to claim 1, characterized in that, The weight ratio of sodium octenyl succinate starch, composite lignin sulfonate, pine bark polyphenols and vanillic acid is 20~55.2:7.1~18.6:2.9~3.0:

1.

3. The low-styrene-volatility unsaturated polyester resin according to claim 1, characterized in that, The total weight of sodium octenyl succinate starch, pine bark polyphenols, vanillic acid, and composite lignin sulfonate accounts for 2.2-3.9% of the weight of the unsaturated polyester resin.

4. The low-styrene-volatility unsaturated polyester resin according to claim 1, characterized in that, The total weight of the sodium octenyl succinate starch, pine bark polyphenols, vanillic acid, and composite lignin sulfonate accounts for 2.4 to 2.7% of the weight of the unsaturated polyester resin.

5. The low-styrene-volatility unsaturated polyester resin according to claim 1, characterized in that, The specific operation of step (1) is to weigh calcium lignosulfonate and sodium lignosulfonate according to their weight parts, dry them under vacuum at 55~65℃ for 2.8~3.2h, and then crush them through a 200-mesh sieve.

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