High-temperature-resistant and corrosion-resistant unsaturated polyester resin for grating and preparation method thereof

Abstract

The invention discloses high-temperature-resistant and corrosion-resistant unsaturated polyester resin for a grid and a preparation method thereof, and belongs to the technical field of unsaturated polyester resin. The raw materials comprise the following components in parts by weight: 330 to 400 parts of isophthalic acid, 55 to 80 parts of 1, 4-cyclohexanedimethanol, 150 to 200 parts of ethylene glycol, 125 to 220 parts of first reaction stage propylene glycol, 0.2 to 0.6 part of a catalyst, 0.1 to 0.3 part of a first reaction stage antioxidant, 90 to 120 parts of second reaction stage propylene glycol, 30 to 50 parts of phthalic anhydride, 300 to 380 parts of maleic anhydride, 0.1 to 0.3 part of a second reaction stage antioxidant, 0.1 to 0.5 part of a polymerization inhibitor and 600 to 630 parts of a cross-linking agent. The high-temperature-resistant and corrosion-resistant unsaturated polyester resin for the grating has the characteristics of high corrosion resistance, high temperature resistance and high mechanical property, is low in cost and is suitable for being used as a raw material for manufacturing the grating.

Description

Technical Field

[0001] The invention discloses a high temperature resistant and corrosion resistant unsaturated polyester resin for a grid and a preparation method thereof, belonging to the technical field of unsaturated resins. Background Art

[0002] Unsaturated polyester resin can be combined with glass fiber or other reinforcing materials, and the resin can be solidified in the mold using mold injection technology to form a grille of the desired shape and size. FRP grilles are currently widely used in many industries due to their advantages such as lighter weight than traditional metal materials, convenient installation and transportation, good safety, good insulation properties, and good comprehensive economic benefits. They play an important role in municipal engineering, chemical industry, construction, automobiles, etc. For example, they are used as petrochemical equipment in chemical plants, work surfaces in chemical laboratories, and food processing equipment and medical equipment with special requirements.

[0003] The applicant found that the grille plate is in the external environment for a long time during application, and is often faced with the test of chemical corrosion, high temperature, sewage, etc. With global warming, the outdoor ground temperature can reach up to 70℃ in summer, and it rains a lot in summer, and acid rain and alkaline rain are more frequent. The existing outdoor ground grilles work in a high temperature, acidic or alkaline soaking environment for a long time, resulting in a shortened lifespan. After the grilles are used for 1-2 summers, the surface of the grilles is corroded, the mechanical properties are reduced, and the load-bearing capacity is deteriorated. It is very easy to cause dangerous accidents when people and vehicles step on the grilles.

[0004] The existing unsaturated polyester resin cannot take into account the mechanical properties while obtaining high corrosion resistance, resulting in poor strength and hardness of the unsaturated polyester resin. After being made into a grille, it cannot bear weight for a long time and cannot be laid on the ground to withstand the pressure of people and vehicles for a long time. In the prior art, unsaturated polyester resin with high mechanical properties is usually used to make grilles, and then the grilles are impregnated or sprayed with corrosion-resistant paint to make the grilles have high mechanical properties and high corrosion resistance at the same time. This design undoubtedly leads to increased costs and complicated production processes.

[0005] There are also designs in the prior art that add prepolymers to make unsaturated polyester resins corrosion-resistant. Patent 201610297956 discloses a high-temperature and corrosion-resistant modified unsaturated polyester resin fiberglass grating, which uses unsaturated polyester resin as the main material, and adds phenolic resin, acrylic alkyd resin, inorganic filler and additives to modify the unsaturated polyester resin. The heat resistance of the unsaturated polyester resin is improved by introducing silicone prepolymers. The performance improvement of this invention mainly depends on the addition of complex types of fillers, additives and expensive silicone prepolymers to modify the resin. The silicone prepolymer will reduce the mechanical strength of the resin, and the overall material cost is high. The invention also does not mention the mechanical properties of the resin.

[0006] There is also a design in the prior art that uses terephthalic acid, neopentyl glycol, and cyclohexanedimethanol to prepare corrosion-resistant resins, but a large proportion of the high-cost neopentyl glycol and cyclohexanedimethanol are used in this design, which increases the production cost of the grille. The grille is usually used on outdoor roads and water collection tanks, and is a consumable item with a large consumption. The high cost is not conducive to the production and application of the grille.

[0007] The corrosion resistance and high temperature resistance of FRP grating produced by existing technology cannot meet the actual use requirements and require regular maintenance and renewal, which greatly limits its application. At present, it is urgent to develop an unsaturated polyester resin with excellent corrosion resistance and high temperature resistance, good mechanical properties and low cost. Summary of the invention

[0008] The technical problem to be solved by the present invention is: to overcome the shortcomings of the prior art and provide a high temperature resistant and corrosion resistant unsaturated polyester resin for a grille and a preparation method thereof. The high temperature resistant and corrosion resistant unsaturated polyester resin for a grille has high corrosion resistance and high temperature resistance, and has high mechanical properties, low cost, and is suitable as a raw material for making grilles.

[0009] The technical solution adopted by the present invention to solve the technical problem is as follows: the high temperature and corrosion resistant unsaturated polyester resin for the grille comprises the following components in parts by weight: 330-400 parts of isophthalic acid, 50-85 parts of 1,4-cyclohexanedimethanol, 150-205 parts of ethylene glycol, 125-220 parts of propylene glycol in the first reaction stage, 0.2-0.6 parts of catalyst, 0.1-0.3 parts of antioxidant in the first reaction stage, 90-120 parts of propylene glycol in the second reaction stage, 30-50 parts of phthalic anhydride, 300-380 parts of maleic anhydride, 0.1-0.3 parts of antioxidant in the second reaction stage, 0.1-0.5 parts of inhibitor and 595-630 parts of crosslinking agent.

[0010] The high temperature resistant and corrosion resistant unsaturated polyester resin for the grille comprises the following components in parts by weight: 343.5-398.9 parts of isophthalic acid, 55-80 parts of 1,4-cyclohexanedimethanol, 155-200 parts of ethylene glycol, 129.4-214.1 parts of propylene glycol in the first reaction stage, 0.4-0.5 parts of catalyst, 0.2-0.25 parts of antioxidant in the first reaction stage, 107.6-115.7 parts of propylene glycol in the second reaction stage, 35-45 parts of phthalic anhydride, 319.5-374.1 parts of maleic anhydride, 0.2-0.25 parts of antioxidant in the second reaction stage, 0.2-0.3 parts of inhibitor and 600-625 parts of crosslinking agent.

[0011] The mass ratio of isophthalic acid to 1,4-cyclohexanedimethanol is 4 to 7: 1. Preferably, the mass ratio of isophthalic acid to 1,4-cyclohexanedimethanol is 4.3 to 6.7: 1. If the amount of 1,4-cyclohexanedimethanol is too small, the comprehensive performance of the product will be reduced.

[0012] The mass ratio of the ethylene glycol, the propylene glycol in the first reaction stage, and the propylene glycol in the second reaction stage is 1:0.6~1.5:0.4~1.0. Preferably, the mass ratio of the ethylene glycol, the propylene glycol in the first reaction stage, and the propylene glycol in the second reaction stage is 1:0.73~1.4:0.5~0.7.

[0013] The catalyst is monobutyl tin oxide. Monobutyl tin oxide is added as a catalyst in step 1), which can accelerate the esterification reaction between polyol and isophthalic acid, increase the reaction rate, reduce possible side reactions during the production process, and help form a more uniform and stable polyester molecular structure.

[0014] The antioxidant in the first reaction stage and the antioxidant in the second reaction stage are both triphenyl phosphite.

[0015] The mass ratio of phthalic anhydride to maleic anhydride is 1:7-10.0.

[0016] The polymerization inhibitor is hydroquinone, and the cross-linking agent is styrene.

[0017] The molar ratio of unsaturated acid to saturated acid in the raw material is 1.2-1.58:1; the molar ratio of alcohol to acid in the raw material is 1.08-1.22:1.

[0018] The preparation method of the high temperature resistant and corrosion resistant unsaturated polyester resin for the grid comprises the following steps: 1) Add isophthalic acid, 1,4-cyclohexanedimethanol, ethylene glycol, propylene glycol for the first reaction stage, catalyst and antioxidant for the first reaction stage into the reactor according to weight, introduce nitrogen, raise the temperature to 208-210°C for insulation reaction, and react until the material in the reactor is clear and transparent, and the acid value of the material is ≤10mgKOH / g; 2) Cool down to 110~120℃, add propylene glycol, phthalic anhydride, maleic anhydride and antioxidant of the second reaction stage into the reactor by weight, introduce nitrogen, heat to 170~180℃ and keep warm for 25~35min, heat to 203~206℃ at a rate of 12~18℃ / h and keep warm for reaction until the acid value of the material is 65~80mgKOH / g, evacuate, continue to react until the acid value of the material is 28~34mgKOH / g, and the cone plate viscosity is 490~510cP (150℃), and release the vacuum; 3) Cool down to 170~190℃, add inhibitor into the reactor; cool down to below 120℃, add cross-linking agent, stir evenly to obtain unsaturated polyester resin.

[0019] Preferably, the specific operation of heating to 208-210°C for heat preservation reaction in step 1) is: heating to 125-135°C at a rate of 12-18°C / h, starting stirring, and continuing to heat to 208-210°C for heat preservation reaction, and the water and alcohol distilled during the heat preservation process are refluxed back into the reactor through condensation.

[0020] The technical solution of the present invention is described as follows: First, isophthalic acid and 1,4-cyclohexanedimethanol are used together to carry out a heat preservation reaction in the first stage reaction of step 1), which can synergistically improve the corrosion resistance, heat resistance and mechanical properties of the unsaturated polyester resin, and obtain an unsaturated polyester resin with all three properties at a lower cost.

[0021] Due to the cyclic structure of 1,4-cyclohexanedimethanol, it can make the polyester chain have a better balance of rigidity and flexibility than other alcohols. Compared with linear polyols, the cyclic structure helps to form a stronger polyester network. The synthesized polyester resin has higher thermal stability, which enables the product to maintain its performance unchanged under high temperature environment and is more suitable for high temperature applications. 1,4-cyclohexanedimethanol can increase the degree of polymerization of polyester, interfere with the crystallization behavior of polyester resin, greatly improve the mechanical properties and chemical stability of the resin, improve the resistance to environmental stress cracking, and thus reduce the generation of cracks. Cracks are the main way for corrosive media to invade the internal structure. Under high temperature conditions, molecules are not easy to break or degrade, thereby improving corrosion resistance. During the curing process, the shrinkage of polyester resin can be reduced. This feature is very important in high-demand applications such as precision casting.

[0022] The purpose of introducing isophthalic acid is to further improve the thermal stability, chemical stability and mechanical properties of the resin. The applicant found in the study that isophthalic acid has better stability and mechanical properties than phthalic anhydride; although terephthalic acid also has good stability in theory, its reaction activity is lower than that of isophthalic acid when terephthalic acid is used; and only when isophthalic acid is introduced, the thermal stability and chemical stability of the resin obtained by the reaction are good. Because there are strong intermolecular forces between the polyester chains formed by the reaction of isophthalic acid and polyols, these forces help to form a tighter molecular network, making it difficult to be penetrated by corrosive media, and can improve the material's solubility resistance and chemical corrosion resistance. The molecular structure of isophthalic acid contains benzene rings, which makes it hydrophobic. The hydrophobic property can reduce the penetration of water molecules into the resin, thereby reducing the chemical or physical degradation caused by water. In many corrosive environments, water is the main corrosive medium, so reducing the penetration of water can effectively improve the chemical stability of polyester resins.

[0023] Since isophthalic acid and ethylene glycol have poor compatibility with styrene, propylene glycol and phthalic anhydride are added to the formula to improve it. Adding maleic anhydride can adjust the unsaturation and activity of the polyester chain. If the unsaturation is too low, it will affect the stability and mechanical properties of the resin, and the post-curing temperature will also be too high.

[0024] The mass ratio of isophthalic acid to 1,4-cyclohexanedimethanol is 4-7:1, which is the best ratio. Preferably, the mass ratio of isophthalic acid to 1,4-cyclohexanedimethanol is 4.3-6.7:1. If the amount of 1,4-cyclohexanedimethanol is too small, the comprehensive performance of the product will be reduced. If the amount of 1,4-cyclohexanedimethanol is too large, when the performance has reached the requirements, the raw material cost of the resin will increase, and the cost performance will be reduced.

[0025] Second, phthalic anhydride and maleic anhydride are added together in the second stage reaction of step 2) in a specific mass ratio instead of in step 1), and the effect is: 1. If phthalic anhydride and maleic anhydride are added in step 1), it will be difficult for isophthalic acid to participate in the reaction because of its low reactivity.

[0026] 2. In step 1), the isophthalic acid with low activity is first fully reacted with excess diol, and then phthalic anhydride and maleic anhydride are added in step 2) to continue the esterification reaction.

[0027] 3. The mass ratio of phthalic anhydride to maleic anhydride is 1:7~10.0. If too much maleic anhydride is added, the polyester chain unsaturation will be too high, which will affect the acid and alkali stability of the resin; if too little maleic anhydride is added, the resin curing speed will be slow and the compatibility with styrene will be poor. Phthalic anhydride and maleic anhydride can work together to improve the compatibility and environmental stability of the resin with styrene.

[0028] Third, regarding ethylene glycol and propylene glycol in the first reaction stage and propylene glycol in the second reaction stage.

[0029] 1. A mixture of ethylene glycol in step 1) and propylene glycol in the first reaction stage at a mass ratio of 1:0.7-1.4. The appropriate addition of ethylene glycol and propylene glycol can reduce the cost of raw materials, and the performance of the prepared product meets the requirements. Propylene glycol has the characteristics of improving the compatibility of resin and styrene, and also has good hydrolysis resistance. The two can cooperate with each other to synergistically enhance the effect, reduce costs and improve product compatibility.

[0030] 2. In step 2), propylene glycol is added in two reaction stages because if too much alcohol is added in the first stage, more alcohol will be evaporated and lost during the reaction. Adding it in two steps can avoid the need for central control feed supplementation in the later stage.

[0031] 3. The cost of ethylene glycol and propylene glycol is relatively low, only 4-6 of the cost of neopentyl glycol, which can significantly reduce the production cost of resin.

[0032] Fourth, the activity ratio in the raw material is the molar ratio of unsaturated acid to saturated acid, and the calculation formula is: The molar ratio of unsaturated acid to saturated acid in the raw material = moles of unsaturated acid / moles of saturated acid Fifth, the molar ratio of total alcohol to total acid in the raw materials is calculated as follows: The molar ratio of total alcohol to total acid in the raw material = (moles of ethylene glycol + moles of propylene glycol + moles of 1,4-cyclohexanedimethanol) / (moles of isophthalic acid + moles of maleic anhydride + moles of phthalic anhydride) Compared with the prior art, the high temperature resistant and corrosion resistant unsaturated polyester resin for grille and the preparation method thereof of the present invention have the following beneficial effects: 1. The high temperature resistant and corrosion resistant unsaturated polyester resin for the grille of the present invention has high corrosion resistance and high temperature resistance, high mechanical properties, low cost, and is suitable as a raw material for making grilles. The present invention introduces 1,4-cyclohexanedimethanol and isophthalic acid into the synthetic raw materials. The joint addition of the two greatly improves the corrosion resistance and high temperature resistance of the resin, and the degree of improvement is more significant than when isophthalic acid is added alone. The addition of ethylene glycol and propylene glycol significantly reduces the cost while maintaining high corrosion resistance and heat stability.

[0033] 2. The high temperature resistant and corrosion resistant unsaturated polyester resin used for the grille of the present invention has good heat resistance and does not deform for 8 hours at 80°C, or even for 8 hours at 100°C. When the grille is made of the unsaturated polyester resin of the present invention and is used outdoors, it can withstand the hot summer temperature for a long time and is not easily deformed by people or vehicles.

[0034] 3. The preparation method of the high temperature resistant and corrosion resistant unsaturated polyester resin for grilles of the present invention adopts a two-stage reaction, and the reaction process is easy to control. The unsaturated polyester resin prepared by the preparation method of the present invention has good mechanical properties and hardness, and a high heat deformation temperature, thereby achieving the purpose of extending the service life of the glass fiber reinforced plastic grille material, expanding the application range of the product, allowing it to be used in more harsh environments, reducing maintenance and replacement costs, and having higher economic benefits. DETAILED DESCRIPTION

[0035] The present invention is further described in detail below in conjunction with specific examples, but the implementation of the present invention is not limited thereto. Example 3 is the best example. The formula of the example is shown in Table 1.

[0036] Ethylene glycol, propylene glycol, maleic anhydride, phthalic anhydride, isophthalic acid, hydroquinone, styrene: analytical grade, all purchased from Aladdin Reagent Co., Ltd.; 1,4-cyclohexanedimethanol, purchased from Shandong Gaotai Chemical Technology Co., Ltd., purity ≥ 99%; monobutyltin oxide, analytical grade, purchased from Guangdong Yuanfeng Chemical Reagent Co., Ltd.; triphenyl phosphite, purchased from Shandong Duolian Chemical Co., Ltd., purity ≥ 97%.

[0037] Table 1 Ratio of raw materials used in the examples (by weight) .

[0038] Example 1 The method for preparing the high temperature resistant and corrosion resistant unsaturated polyester resin for the grid of this embodiment comprises the following steps: 1) Add isophthalic acid, 1,4-cyclohexanedimethanol, ethylene glycol, propylene glycol for the first reaction stage, catalyst and antioxidant for the first reaction stage into the reactor according to weight parts, continuously introduce nitrogen into the reactor, raise the temperature to 132°C at a rate of 14°C / h, start stirring, continue to raise the temperature to 209°C for insulation reaction, water and alcohol distilled during the insulation process are condensed and refluxed back into the reactor, and the insulation reaction is carried out until the material is clear and transparent, and the acid value of the material is ≤10mgKOH / g; 2) Cool down to 116°C, add propylene glycol, phthalic anhydride, maleic anhydride and antioxidant of the second reaction stage by weight, continue to introduce nitrogen, heat to 173°C and keep warm for 32 minutes, heat to 204°C at a rate of 14°C / h and keep warm for reaction. When the acid value of the material in the reactor reaches 68-75 mgKOH / g, evacuate the reactor to 0.07 MPa, continue to react until the acid value of the material reaches 29-31 mgKOH / g, and the cone plate viscosity reaches 497-503 cP (150°C), and release the vacuum with inert gas; 3) Cool down to 185°C and add inhibitor; cool down to 117°C and add cross-linking agent and stir evenly to obtain high temperature and corrosion resistant unsaturated polyester resin for grid.

[0039] Example 2 The method for preparing the high temperature resistant and corrosion resistant unsaturated polyester resin for the grid of this embodiment comprises the following steps: 1) Add isophthalic acid, 1,4-cyclohexanedimethanol, ethylene glycol, propylene glycol for the first reaction stage, catalyst and antioxidant for the first reaction stage into the reactor according to weight parts, continuously introduce nitrogen into the reactor, raise the temperature to 128°C at a rate of 16°C / h, start stirring, continue to raise the temperature to 209°C for insulation reaction, water and alcohol distilled during the insulation process are condensed and refluxed back into the reactor, and insulation reaction is carried out until the material is clear and transparent, and the acid value of the material is ≤10mgKOH / g; 2) Cool down to 113°C, add propylene glycol, phthalic anhydride, maleic anhydride and antioxidant of the second reaction stage by weight, continue to introduce nitrogen, heat to 177°C and keep warm for 28 minutes, heat to 203°C at a rate of 16°C / h and keep warm for reaction. When the acid value of the material in the reactor reaches 68-75 mgKOH / g, evacuate the reactor to 0.07 MPa, continue to react until the acid value of the material reaches 32-34 mgKOH / g, and the cone plate viscosity reaches 500-510 cP (150°C), and release the vacuum with inert gas; 3) Cool down to 175℃ and add inhibitor; cool down to 113℃ and add cross-linking agent and stir evenly to obtain high temperature and corrosion resistant unsaturated polyester resin for grid.

[0040] Example 3 The method for preparing the high temperature resistant and corrosion resistant unsaturated polyester resin for the grid of this embodiment comprises the following steps: 1) Add isophthalic acid, 1,4-cyclohexanedimethanol, ethylene glycol, propylene glycol for the first reaction stage, catalyst and antioxidant for the first reaction stage into the reactor according to weight parts, continuously introduce nitrogen into the reactor, heat up to 130°C at a rate of 15°C / h, start stirring, continue to heat up to 209°C for insulation reaction, water and alcohol distilled out during the insulation process are condensed and refluxed back into the reactor, and insulation reaction is carried out until the material is clear and transparent, and the acid value of the material is ≤10mgKOH / g; 2) Cool down to 115°C, add propylene glycol, phthalic anhydride, maleic anhydride and antioxidant of the second reaction stage by weight, continue to introduce nitrogen, heat to 175°C and keep warm for 30 minutes, heat to 204°C at a rate of 15°C / h and keep warm for reaction. When the acid value of the material in the reactor reaches 70mgKOH / g, evacuate the reactor to 0.07MPa, continue to react until the acid value of the material reaches 30-31mgKOH / g, and the cone plate viscosity reaches 495-505cP (150°C), and release the vacuum with inert gas; 3) Cool down to 180℃ and add polymerization inhibitor; cool down to 115℃ and add cross-linking agent and stir evenly to obtain high temperature and corrosion resistant unsaturated polyester resin for grid.

[0041] Example 4 The method for preparing the high temperature resistant and corrosion resistant unsaturated polyester resin for the grid of this embodiment comprises the following steps: 1) Add isophthalic acid, 1,4-cyclohexanedimethanol, ethylene glycol, propylene glycol for the first reaction stage, catalyst and antioxidant for the first reaction stage into the reactor according to weight parts, continuously introduce nitrogen into the reactor, heat up to 125°C at a rate of 18°C / h, start stirring, continue to heat up to 210°C for insulation reaction, water and alcohol distilled out during the insulation process are condensed and refluxed back into the reactor, and insulation reaction is carried out until the material is clear and transparent, and the acid value of the material is ≤10mgKOH / g; 2) Cool down to 110°C, add propylene glycol, phthalic anhydride, maleic anhydride and antioxidant of the second reaction stage by weight, continue to introduce nitrogen, heat to 180°C and keep warm for 25 minutes, heat to 206°C at a rate of 18°C / h and keep warm for reaction. When the acid value of the material in the reactor reaches 80mgKOH / g, evacuate the reactor to 0.05MPa, continue to react until the acid value of the material reaches 28-29mgKOH / g, and the cone plate viscosity reaches 490~500cP (150°C), and release the vacuum with inert gas; 3) Cool down to 190℃ and add polymerization inhibitor; cool down to 110℃ and add cross-linking agent and stir evenly to obtain high temperature and corrosion resistant unsaturated polyester resin for grille.

[0042] Example 5 The method for preparing the high temperature resistant and corrosion resistant unsaturated polyester resin for the grid of this embodiment comprises the following steps: 1) Add isophthalic acid, 1,4-cyclohexanedimethanol, ethylene glycol, propylene glycol for the first reaction stage, catalyst and antioxidant for the first reaction stage into the reactor according to weight parts, continuously introduce nitrogen into the reactor, raise the temperature to 135°C at a rate of 12°C / h, start stirring, continue to raise the temperature to 208°C for insulation reaction, water and alcohol distilled during the insulation process are condensed and refluxed back into the reactor, and the insulation reaction is carried out until the material is clear and transparent, and the acid value of the material is ≤10mgKOH / g; 2) Cool down to 120°C, add propylene glycol, phthalic anhydride, maleic anhydride and antioxidant of the second reaction stage by weight, continue to introduce nitrogen, heat to 170°C and keep warm for 35 minutes, heat to 206°C at a rate of 12°C / h and keep warm for reaction. When the acid value of the material in the reactor reaches 65mgKOH / g, evacuate the reactor to 0.08MPa, continue to react until the acid value of the material reaches 28-29mgKOH / g, and the cone plate viscosity reaches 490~500cP (150°C), and release the vacuum with inert gas; 3) Cool down to 170℃ and add polymerization inhibitor; cool down to 120℃ and add cross-linking agent and stir evenly to obtain high temperature and corrosion resistant unsaturated polyester resin for grille.

[0043] Comparative Example 1 This comparative example is the same as Example 3, except that isophthalic acid is replaced with an equal mass of terephthalic acid.

[0044] Comparative Example 2 This comparative example is the same as Example 3, except that: 410.2 parts of isophthalic acid, 28 parts of 1,4-cyclohexanedimethanol; The total mass of isophthalic acid and 1,4-cyclohexanedimethanol remains unchanged, and the mass ratio of isophthalic acid to 1,4-cyclohexanedimethanol is adjusted to 14.65:1.

[0045] Comparative Example 3 This comparative example is the same as Example 3, except that: 199.3 parts of phthalic anhydride and 199.3 parts of maleic anhydride; The total mass of the anhydride remained unchanged, and the mass ratio of phthalic anhydride to maleic anhydride was adjusted to 1:1.

[0046] Comparative Example 4 This comparative example is the same as Example 3, except that: 31.9 parts of phthalic anhydride and 366.7 parts of maleic anhydride; The total mass of anhydride remained unchanged, and the mass ratio of phthalic anhydride to maleic anhydride was adjusted to 1:12.5.

[0047] Comparative Example 5 This comparative example is the same as Example 3, except that: the total mass of 277.1 parts of propylene glycol remains unchanged; Propylene glycol is not added in step 1) but is added all at once in step 2).

[0048] Comparative Example 6 This comparative example is the same as Example 3, except that: the preparation method adopts a one-step synthesis; the raw material composition and dosage of this comparative example are the same as those of Example 3, but propylene glycol and antioxidant are added at one time; The preparation method of the unsaturated polyester resin of this comparative example comprises the following steps: 1) Add isophthalic acid, 1,4-cyclohexanedimethanol, ethylene glycol, propylene glycol (the sum of the amounts of propylene glycol in the first reaction stage and the second reaction stage), phthalic anhydride, maleic anhydride, catalyst and antioxidant (the sum of the amounts of antioxidant in the first reaction stage and the second reaction stage) into the reactor according to weight parts, continuously introduce nitrogen into the reactor, raise the temperature to 130°C at a rate of 15°C / h, start stirring, continue to raise the temperature to 209°C for insulation reaction, and keep the temperature for reaction until the acid value of the material in the reactor reaches 70mgKOH / g, then evacuate the reactor to 0.07MPa, continue to react until the acid value of the material reaches 30mgKOH / g, and release the vacuum with inert gas; 2) Cool down to 180℃ and add polymerization inhibitor; cool down to below 115℃ and add cross-linking agent and stir evenly to obtain high temperature and corrosion resistant unsaturated polyester resin for grid.

[0049] Performance Testing 1. Mechanical properties test The unsaturated polyester resins obtained in the examples and comparative examples were made into resin castings and subjected to mechanical property tests. The test results are shown in Table 3 below.

[0050] Tensile strength test standard GB / T2567-2008; unit MPa; Tensile elastic modulus test standard GB / T2567-2008; unit MPa; Elongation at break test standard GB / T2567-2008; unit: % Bending strength test standard GB / T2567-2008; unit MPa; Bending elastic modulus test standard GB / T2567-2008; unit MPa; Impact strength test standard GB / T2567-2008; unit KJ / M 2 ; Barcol hardness test standard GB / T3854-2005; unit HBa; Heat deformation temperature test standard GB / T2567-2008; unit: ℃.

[0051] Table 2 Mechanical properties of examples and comparative examples .

[0052] 2. Corrosion resistance test The casting products prepared by the unsaturated polyester resin for grid obtained in the embodiment and the comparative example were respectively tested for corrosion resistance. The casting products were immersed in 10% solutions of hydrochloric acid, sulfuric acid and sodium hydroxide at different concentrations at 30°C for 20 days (480 hours) to test the mass change rate, and the appearance changes of the samples before and after immersion were recorded. The test results are shown in Table 4 below.

[0053] Table 3 Corrosion resistance of examples and comparative examples .

[0054] 3. High temperature resistance test The casting products prepared by the unsaturated polyester resin for grid obtained in the examples and comparative examples were subjected to high temperature resistance test, and the casting products were placed in ovens at 80°C and 100°C for 8 hours, taken out and cooled at room temperature, and the changes in the appearance of the samples were observed and recorded. The test results are shown in Table 5 below.

[0055] Table 4 High temperature resistance performance of examples and comparative examples .

[0056] The performance test results of the examples and comparative examples in Tables 2 to 4 can verify that the present invention can improve the corrosion resistance, high temperature resistance and mechanical properties of the resin by adding 1,4-cyclohexanedimethanol and isophthalic acid. Example 3 is the best formula ratio, and the product obtained is more resistant to high temperatures, has strong mechanical properties, can effectively resist chemical erosion, and prolongs the service life of the material.

[0057] 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 high temperature resistant and corrosion resistant unsaturated polyester resin for grille, characterized in that: The raw materials include the following components in parts by weight: 330-400 parts of isophthalic acid, 50-85 parts of 1,4-cyclohexanedimethanol, 150-205 parts of ethylene glycol, 125-220 parts of propylene glycol in the first reaction stage, 0.2-0.6 parts of catalyst, 0.1-0.3 parts of antioxidant in the first reaction stage, 90-120 parts of propylene glycol in the second reaction stage, 30-50 parts of phthalic anhydride, 300-380 parts of maleic anhydride, 0.1-0.3 parts of antioxidant in the second reaction stage, 0.1-0.5 parts of inhibitor, and 595-630 parts of cross-linking agent.

2. The high temperature resistant and corrosion resistant unsaturated polyester resin for grille according to claim 1, characterized in that: The raw materials include the following components in parts by weight: 343.5-398.9 parts of isophthalic acid, 55-80 parts of 1,4-cyclohexanedimethanol, 155-200 parts of ethylene glycol, 129.4-214.1 parts of propylene glycol in the first reaction stage, 0.4-0.5 parts of catalyst, 0.2-0.25 parts of antioxidant in the first reaction stage, 107.6-115.7 parts of propylene glycol in the second reaction stage, 35-45 parts of phthalic anhydride, 319.5-374.1 parts of maleic anhydride, 0.2-0.25 parts of antioxidant in the second reaction stage, 0.2-0.3 parts of inhibitor, and 600-625 parts of cross-linking agent.

3. The high temperature resistant and corrosion resistant unsaturated polyester resin for grille according to claim 1 or 2, characterized in that: The mass ratio of isophthalic acid to 1,4-cyclohexanedimethanol is 4-7:

1.

4. The high temperature resistant and corrosion resistant unsaturated polyester resin for grille according to claim 1 or 2, characterized in that: The mass ratio of the ethylene glycol, the propylene glycol in the first reaction stage and the propylene glycol in the second reaction stage is 1:0.6~1.5:0.4~1.

0.

5. The high temperature resistant and corrosion resistant unsaturated polyester resin for grille according to claim 1 or 2, characterized in that: The catalyst is monobutyltin oxide.

6. The high temperature resistant and corrosion resistant unsaturated polyester resin for grille according to claim 1 or 2, characterized in that: The antioxidant in the first reaction stage and the antioxidant in the second reaction stage are both triphenyl phosphite.

7. The high temperature resistant and corrosion resistant unsaturated polyester resin for grille according to claim 1 or 2, characterized in that: The mass ratio of phthalic anhydride to maleic anhydride is 1:7-10.

0.

8. The high temperature resistant and corrosion resistant unsaturated polyester resin for grille according to claim 1 or 2, characterized in that: The polymerization inhibitor is hydroquinone, and the cross-linking agent is styrene.

9. The high temperature resistant and corrosion resistant unsaturated polyester resin for grille according to claim 1 or 2, characterized in that: The molar ratio of unsaturated acid to saturated acid in the raw material is 1.2-1.58:1; the molar ratio of alcohol to acid in the raw material is 1.08-1.21:

1.

10. The method for preparing the high temperature resistant and corrosion resistant unsaturated polyester resin for grille according to any one of claims 1 to 9, characterized in that: The steps include: 1) Add isophthalic acid, 1,4-cyclohexanedimethanol, ethylene glycol, propylene glycol for the first reaction stage, catalyst and antioxidant for the first reaction stage into the reactor according to weight, introduce nitrogen, raise the temperature to 208-210°C for insulation reaction, and react until the material in the reactor is clear and transparent, and the acid value of the material is ≤10mgKOH / g; 2) Cool down to 110~120℃, add propylene glycol, phthalic anhydride, maleic anhydride and antioxidant of the second reaction stage into the reactor by weight, introduce nitrogen, heat to 170~180℃ and keep warm for 25~35min, heat to 203~206℃ at a rate of 12~18℃ / h and keep warm for reaction until the acid value of the material is 65~80mgKOH / g, evacuate, continue to react until the acid value of the material is 28~34mgKOH / g, and the cone plate viscosity is 490~510cP (150℃), and release the vacuum; 3) Cool down to 170~190℃, add polymerization inhibitor into the reactor; cool down to below 120℃, add cross-linking agent, stir evenly, and obtain high temperature and corrosion resistant unsaturated polyester resin for grid.