A lightweight, corrosion-resistant fiberglass profile and its preparation method

Abstract

This invention relates to the field of glass fiber reinforced composite materials, and discloses a lightweight, corrosion-resistant fiberglass profile and its preparation method. The profile comprises continuous E-glass fibers and a cured resin composition. The cured resin composition is formed by curing isophenylene-neopentyl glycol type unsaturated polyester resin, styrene, phosphate ester-vinyl-terminated interface-modified oligomers, ground E-glass fibers, aluminum hydroxide flame-retardant filler, a release agent, an antifoaming agent, and a composite curing system. The interface-modified oligomers are prepared by reacting hydroxyl-terminated unsaturated polyester oligomers, polyphosphoric acid, and glycidyl methacrylate. This invention is beneficial for improving the flexural strength retention rate after immersion in acidic or alkaline media, while also considering lightweight properties, flame-retardant filler dispersion, and stability during continuous pultrusion molding.

Description

Technical Field

[0001] This invention relates to the field of glass fiber reinforced composite materials technology, and in particular to a lightweight and corrosion-resistant fiberglass profile and its preparation method. Background Technology

[0002] Glass fiber reinforced unsaturated polyester resin materials, commonly known as fiberglass, have a lower density than steel and possess higher specific strength, corrosion resistance, electrical insulation, and design flexibility. Pultrusion is a common process for manufacturing continuous cross-section fiberglass profiles. Continuous glass fibers are impregnated with resin and then fed into a heated mold, where they are continuously cured under traction to produce angle rods, channel rods, square tubes, strips, and other irregularly shaped cross-section products. These profiles have been used in chemical platforms, wastewater treatment plants, cooling towers, electrical insulation supports, marine facilities, and other applications involving humid or acidic / alkaline media.

[0003] Existing fiberglass pultruded profiles mostly use unsaturated polyester resin, vinyl ester resin, or epoxy resin as the matrix, and continuous glass fiber, glass fiber mat, or fabric as the reinforcing material. Components such as aluminum hydroxide, calcium carbonate, low-shrinkage agents, release agents, and curing agents are added to meet requirements for molding, flame retardancy, mechanical properties, or cost. Patent CN103351639A discloses a production process for high-strength flame-retardant fiberglass pultruded profiles, which involves mixing unsaturated resin, flame retardant, and curing agent into a resin liquid, then impregnating the fibers before curing in a pre-forming mold and a molding mold. The flame retardant may include aluminum hydroxide and phosphate esters. This type of solution mainly focuses on the flame retardant and the curing process, but it does not adequately consider the stability of the resin residence within the continuous fiber bundle and the penetration of acid and alkali media along the interface.

[0004] Patent CN114773817B discloses a fiberglass pultruded profile and its preparation method, employing unsaturated polyester resin, epoxy resin, curing agent, release agent, low-shrinkage agent, flame retardant, and biaxial fabric of glass fiber and composite glass fiber to improve transverse mechanical properties and flame retardant properties. This method improves profile performance through the resin system and reinforcing material structure; however, its formulation has many components, focusing primarily on the biaxial fabric and composite resin system, and does not specifically control the water absorption weight gain and strength retention decrease at the interface between the unsaturated polyester resin and continuous E-glass fiber after acid and alkali immersion.

[0005] In long-term acidic, alkaline, or humid environments, the performance degradation of fiberglass profiles depends not only on the resin's resistance to the medium but also on the quality of fiber bundle wetting, resin drainage, curing shrinkage, and the continuous channels at the fiber-resin interface. Simply increasing the amount of corrosion-resistant resin or using high-cost resin may increase costs and alter pultrusion viscosity and curing window; conversely, adding large amounts of inorganic fillers to improve flame retardancy or reduce costs may increase system viscosity, cause insufficient wetting, or lead to localized interface defects during curing shrinkage. Therefore, there is still room for improvement in how to balance low density, strength retention after medium resistance, flame-retardant filler dispersion, and continuous pultrusion process stability in conventional unsaturated polyester pultrusion systems. Summary of the Invention

[0006] In view of this, the purpose of this invention is to propose a lightweight and corrosion-resistant fiberglass profile and its preparation method, so as to solve the problems that conventional unsaturated polyester pultruded profiles are prone to water absorption and weight gain, and decreased flexural strength retention rate after being subjected to acid and alkali media, and it is difficult to simultaneously achieve lightweight, flame-retardant filler dispersion and continuous pultrusion process stability.

[0007] To achieve the above objectives, the present invention provides a lightweight corrosion-resistant fiberglass profile, comprising continuous E-glass fiber and a cured resin composition; based on the total mass of the lightweight corrosion-resistant fiberglass profile, the content of the continuous E-glass fiber is 60%-62%, and the remainder is the cured resin composition; The cured resin composition is formed by curing an unsaturated polyester resin composition for pultrusion. Based on 100 parts by weight of isophenylene-neopentyl glycol type unsaturated polyester resin, the unsaturated polyester resin composition for pultrusion comprises: 3.8-4.5 parts by weight of styrene, 1.2-3.0 parts by weight of phosphate ester-vinyl end-modified interface-modified oligomer, 1.5-3.5 parts by weight of ground E glass fiber, 8-12 parts by weight of aluminum hydroxide flame retardant filler, 0.55-0.75 parts by weight of zinc stearate, 0.12-0.18 parts by weight of polyether modified defoamer, 1.10-1.50 parts by weight of 50% benzoyl peroxide paste, and 0.60-0.90 parts by weight of tert-butyl peroxide. The phosphate ester-vinyl end-modified interface-regulating oligomers are prepared by reacting hydroxyl-terminated unsaturated polyester oligomers, polyphosphoric acid, and glycidyl methacrylate, and include short-chain high-acid-value phosphate ester-vinyl end-modified interface-regulating oligomers and long-chain low-acid-value phosphate ester-vinyl end-modified interface-regulating oligomers. The number-average molecular weight of the short-chain high-acid-value phosphate ester-vinyl end-modified interface-regulating oligomers is 950-1250, and the acid value is 16-22 mgKOH / g. The number-average molecular weight of the long-chain low-acid-value phosphate ester-vinyl end-modified interface-regulating oligomers is 1400-1800, and the acid value is 8-14 mgKOH / g. The mass ratio of the short-chain high-acid-value phosphate ester-vinyl end-modified interface-regulating oligomers to the long-chain low-acid-value phosphate ester-vinyl end-modified interface-regulating oligomers is 1:(1.5-1.9).

[0008] Further, the average length of the ground E-glass fiber is 45-90 μm, and the moisture content is not greater than 0.10%; the median particle size of the aluminum hydroxide flame retardant filler is 8-10 μm; the pultrusion unsaturated polyester resin composition has a Brookfield viscosity of 650-900 mPa·s measured at 25℃, rotor No. 4, and 60 r / min, and a gel time of 155-190 s measured at 80℃; the isophenylene-neopentyl glycol type unsaturated polyester resin has a Brookfield viscosity of 520-620 mPa·s at 25℃, an acid value of 18-23 mg KOH / g, and a solid content of 62%-66%; the continuous E-glass fiber is an untwisted roving of E-glass fiber with a linear density of 2400 tex; and the density of the lightweight corrosion-resistant fiberglass profile tested according to GB / T 1463-2005 is 1.69-1.76 g / cm³.

[0009] This invention also provides a method for preparing the above-mentioned lightweight corrosion-resistant fiberglass profile, comprising the following steps: preparing the phosphate ester-vinyl end-modified interface-controlled oligomer; mixing isophenylene-neopentyl glycol type unsaturated polyester resin and styrene, adding short-chain high-acid-value phosphate ester-vinyl end-modified interface-controlled oligomer and stirring, adding ground E glass fiber for dispersion, then adding aluminum hydroxide flame-retardant filler for dispersion, subsequently adding long-chain low-acid-value phosphate ester-vinyl end-modified interface-controlled oligomer, adding zinc stearate, polyether modified defoamer, 50% benzoyl peroxide paste and tert-butyl peroxide to obtain an unsaturated polyester resin composition for pultrusion; and then impregnating continuous E glass fiber with the unsaturated polyester resin composition for pultrusion and curing it in a pultrusion mold.

[0010] Further, in preparing the phosphate ester-vinyl end-modified interface-regulated oligomer, maleic anhydride, adipic acid, neopentyl glycol, and 1,2-propanediol are first subjected to a polycondensation reaction under nitrogen protection to obtain a hydroxyl-terminated unsaturated polyester oligomer. Then, the hydroxyl-terminated unsaturated polyester oligomer is reacted with polyphosphoric acid at 80-84°C, followed by the dropwise addition of glycidyl methacrylate and a holding time at 84°C for 130-150 min. The ground E-glass fiber is added after the addition of the short-chain, high-acid-value phosphate ester-vinyl end-modified interface-regulated oligomer and before the addition of the aluminum hydroxide flame-retardant filler, at a speed of 450-550 r / min. Disperse for 15-20 min; the long-chain low-acid-value phosphate ester-vinyl end-grouped interface-modified oligomer is added dropwise after the aluminum hydroxide flame retardant filler is dispersed, and before the addition of the 50% benzoyl peroxide paste and the tert-butyl peroxide, with a dropwise addition time of 15-20 min; the pultrusion die includes an inlet section, a middle section, and an outlet section, with the inlet section temperature being 90-100℃, the middle section temperature being 130-140℃, and the outlet section temperature being 150-160℃, and the traction speed being 0.30-0.40 m / min; after demolding, it is post-cured for 20 min in a 120℃ hot air channel.

[0011] The beneficial effects of this invention are as follows: This invention employs a phosphate ester-vinyl-terminated interface-modifying oligomer prepared from hydroxyl-terminated unsaturated polyester oligomers, polyphosphoric acid, and glycidyl methacrylate, and limits its number-average molecular weight, acid value, and addition amount to a range compatible with isophenylene-neopentyl glycol type unsaturated polyester resin. This oligomer contains a phosphate ester structure that can interact polarly with the glass phase, and also contains vinyl end groups that can participate in resin curing, which is beneficial for improving resin retention and interface curing within the fiber bundle without significantly increasing the amount of corrosion-resistant resin used.

[0012] This invention divides the interface-modifying oligomer into a short-chain, high-acid-value component and a long-chain, low-acid-value component. The short-chain component is added first to the resin system and dispersed together with the ground E-glass fibers. The long-chain component is added dropwise after the aluminum hydroxide flame-retardant filler is dispersed and before the curing agent is added. This order of addition allows the short-chain component to contact the glass phase surface earlier, while the long-chain component regulates the flow and pre-curing state of the resin system later, which is beneficial for balancing glass fiber wetting, filler dispersion, and subsequent gel curing.

[0013] This invention incorporates homologous ground E-glass fibers into an unsaturated polyester resin composition, and then adds aluminum hydroxide flame-retardant filler after dispersing the fibers in the presence of short-chain, high-acid-value interface-adjusting oligomers. The ground E-glass fibers have similar material properties to continuous E-glass fibers and the resin matrix, which can improve interfacial continuity during localized filling and curing shrinkage without introducing dissimilar high-hardness fillers.

[0014] This invention controls the 25°C Brookfield viscosity and 80°C gel time of the pultrusion resin composition within a specific window, and employs three-stage mold temperatures (inlet, middle, and outlet) and corresponding traction speeds to ensure sufficient resin fluidity during the wetting stage, enabling gradual gelation and curing within the mold. In the composite curing system, 50% benzoyl peroxide paste provides initial curing in the pre- and middle stages, while tert-butyl peroxide provides supplementary curing in the mid- and high-temperature stages, which helps reduce the risk of insufficient curing or excessive drainage.

[0015] Based on comprehensive performance test results, the embodiment of the present invention has a density of approximately 1.69-1.76 g / cm³. 3 Within the oxygen index range of approximately 30.8%-32.4%, the weight gain after soaking in 10% H2SO4 and 5% NaOH for 168 hours was low, and the flexural strength retention rate was high, indicating that the present invention achieves a good balance between lightweight, corrosion resistance and continuous pultrusion molding. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0017] Example 1: The raw materials used in this embodiment are as follows: isophenylene-neopentyl glycol type unsaturated polyester resin was purchased from Shanghai Xintianhe Resin Co., Ltd., model 600N, with a Brookfield viscosity of 560 mPa·s at 25℃, an acid value of 21 mg KOH / g, and a solid content of 65% before use; continuous E glass fiber roving was purchased from China Jushi Co., Ltd., model E6DR24-2400-386T, with a linear density of 2400 tex and a moisture content of 0.06%; ground E glass fiber was purchased from China Beihai Glass Fiber Co., Ltd., model EMG60-W200, with an average length of 60 μm and a moisture content of 0.08%; aluminum hydroxide flame retardant filler was purchased from Huber Engineered Materials, model Hymod SB432SP, with a median particle size of 9 μm.

[0018] (1) Add 490g of maleic anhydride, 292g of adipic acid, 624g of neopentyl glycol, 152g of 1,2-propanediol, and 0.25g of hydroquinone to a reactor equipped with a nitrogen inlet, thermometer, mechanical stirrer, and condenser. Purge with nitrogen until the oxygen content at the reactor outlet is less than 1%. Stir at 250r / min, heat to 145℃ and hold for 60min, then heat to 178℃ and hold for 260min. Then dehydrate under reduced pressure at 178℃ and -0.085MPa for 45min, and cool to 92℃ to obtain a hydroxyl-terminated unsaturated polyester oligomer. The acid value of this hydroxyl-terminated unsaturated polyester oligomer is 6.1mgKOH / g, the hydroxyl value is 102mgKOH / g, and the number average molecular weight is 990. Take the hydroxyl-terminated unsaturated polyester oligomer... 1000g of saturated polyester oligomer was heated to 82℃, and 34g of polyphosphoric acid was added. The mixture was stirred at 350r / min for 90min, and 0.7g of N,N-dimethylbenzylamine was added. 52g of glycidyl methacrylate was added dropwise over 45min, with the temperature controlled at 84℃ during the dropwise addition. After the dropwise addition was completed, the mixture was kept at 84℃ for 150min, and then treated at 75℃ and -0.070MPa for 20min. The mixture was then filtered through a 100-mesh stainless steel sieve to obtain a short-chain high-acid-value phosphate ester-vinyl-terminated interface-modified oligomer. The number-average molecular weight of this short-chain high-acid-value phosphate ester-vinyl-terminated interface-modified oligomer was 1120, the acid value was 18.8mgKOH / g, and the Brookfield viscosity at 25℃ was 930mPa·s. (2) Add 490g of maleic anhydride, 438g of adipic acid, 728g of neopentyl glycol, 152g of 1,2-propanediol, and 0.25g of hydroquinone to a reactor equipped with a nitrogen inlet, thermometer, mechanical stirrer, and condenser. Purge with nitrogen until the oxygen content at the reactor outlet is less than 1%. Stir at 250r / min, raise the temperature to 145℃ and hold for 60min, then raise the temperature to 176℃ and hold for 320min. Then dehydrate under reduced pressure at 176℃ and -0.085MPa for 50min, and cool to 92℃ to obtain a hydroxyl-terminated unsaturated polyester oligomer. The acid value of this hydroxyl-terminated unsaturated polyester oligomer is 5.2mgKOH / g, the hydroxyl value is 67mgKOH / g, and the number average molecular weight is 1530. Take the hydroxyl-terminated unsaturated polyester oligomer... 1000g of saturated polyester oligomer was heated to 80℃, and 20g of polyphosphoric acid was added. The mixture was stirred at 350r / min for 90min, and 0.6g of N,N-dimethylbenzylamine was added. Meanwhile, 42g of glycidyl methacrylate was added dropwise over 40min, with the temperature controlled at 84℃ during the dropwise addition. After the dropwise addition was completed, the mixture was kept at 84℃ for 130min. Subsequently, it was treated at 75℃ and -0.070MPa for 20min and filtered through a 100-mesh stainless steel sieve to obtain a long-chain, low-acid-value phosphate ester-vinyl-terminated interface-modified oligomer. The number-average molecular weight of this long-chain, low-acid-value phosphate ester-vinyl-terminated interface-modified oligomer was 1650, the acid value was 10.6mgKOH / g, and the Brookfield viscosity at 25℃ was 1260mPa·s. (3) Add 100 kg of isophenylene-neopentyl glycol type unsaturated polyester resin and 4.0 kg of styrene to a resin mixing tank at 25°C, stir at 300 r / min for 8 min, add 0.75 kg of short-chain high-acid-value phosphate ester-vinyl end-grouped interface-modified oligomer, stir at 350 r / min for 15 min; add 2.5 kg of homologous ground E glass fiber, disperse at 500 r / min for 18 min, add 10 kg of aluminum hydroxide flame retardant filler, disperse at 600 r / min for 25 min, take a sample and pass it through a 0.30 mm metal sieve, and under stirring at 300 r / min, reduce the long-chain low-acid-value phosphate ester-vinyl end-grouped interface-modified oligomer. 1.35 kg of polymer was added dropwise to the resin mixing vessel over 18 min. After the addition was complete, stirring was continued for 15 min. Then, 0.65 kg of zinc stearate and 0.15 kg of polyether-modified defoamer were added, and the mixture was stirred at 300 r / min for 10 min. Finally, 1.30 kg of 50% benzoyl peroxide paste and 0.75 kg of tert-butyl peroxide were added, and the mixture was stirred at 250 r / min for 8 min to obtain an unsaturated polyester resin composition for pultrusion. The obtained unsaturated polyester resin composition for pultrusion had a Brookfield viscosity of 740 mPa·s at 25 °C, rotor No. 4, and 60 r / min, and a gel time of 172 s at 80 °C. (4) After the continuous E glass fiber roving is untwisted through the tension frame, it enters the impregnation tank of the above-mentioned unsaturated polyester resin composition for pultrusion. The temperature of the impregnation tank is controlled at 25°C. The fiber bundle stays in the impregnation tank for 40 seconds. After the excess resin is removed through the preform plate and the extrusion port, it enters the metal pultrusion die. The temperature of the metal pultrusion die is 95°C at the inlet section, 135°C at the middle section, and 155°C at the outlet section. The traction speed is 0.36 m / min. After demolding, it is post-cured in a 120°C hot air channel for 20 minutes. After cooling to below 35°C, it is cut to obtain a lightweight corrosion-resistant fiberglass profile. The mass content of the continuous E glass fiber in the fiberglass profile is 61%, and the mass content of the cured phase of the resin composition is 39%.

[0019] Example 2: The preparation process in this embodiment is the same as that in Example 1, except that: the short-chain high-acid-value phosphate ester-vinyl end-grouped interface-modified oligomer is prepared using 490g of maleic anhydride, 260g of adipic acid, 606g of neopentyl glycol, 152g of 1,2-propanediol, 39g of polyphosphoric acid, and 56g of glycidyl methacrylate. The resulting oligomer has a number-average molecular weight of 980, an acid value of 21.2mgKOH / g, and a Brookfield viscosity of 860mPa·s at 25℃; the long-chain low-acid-value phosphate ester-vinyl end-grouped interface-modified oligomer is prepared using 490g of maleic anhydride, 392g of adipic acid, 690g of neopentyl glycol, 152g of 1,2-propanediol, 25g of polyphosphoric acid, and 44g of glycidyl methacrylate. The resulting oligomer has a number-average molecular weight of 1420, an acid value of 12.9mgKOH / g, and a Brookfield viscosity of 1090mPa·s at 25℃.

[0020] Add 100 kg of isophenylene-neopentyl glycol type unsaturated polyester resin and 3.8 kg of styrene to a resin mixing vessel at 25°C, and stir at 300 r / min for 8 min. Add 0.48 kg of short-chain high-acid-value phosphate ester-vinyl end-modified interface-adjusting oligomer, and stir at 350 r / min for 15 min. Add 1.5 kg of homologous ground E glass fiber, and disperse at 500 r / min for 18 min. Add 8.0 kg of aluminum hydroxide flame retardant filler, and disperse at 600 r / min for 25 min. After passing the sample through a 0.30 mm metal sieve, and under stirring at 300 r / min, add the long-chain low-acid-value phosphate ester-vinyl end-modified interface-adjusting oligomer. 0.72 kg of acid value phosphate ester-vinyl end-grouped interface-modified oligomer was added dropwise to the resin mixing vessel over 18 min. After the addition was complete, stirring was continued for 15 min. Then, 0.55 kg of zinc stearate and 0.12 kg of polyether-modified defoamer were added, and the mixture was stirred at 300 r / min for 10 min. Finally, 1.10 kg of 50% benzoyl peroxide paste and 0.60 kg of tert-butyl peroxide were added, and the mixture was stirred at 250 r / min for 8 min to obtain an unsaturated polyester resin composition for pultrusion. The resulting composition had a Brookfield viscosity of 665 mPa·s at 25 °C and a gel time of 187 s at 80 °C.

[0021] Continuous E-glass fiber roving is untwisted and spread through a tension frame before entering the impregnation tank of the aforementioned unsaturated polyester resin composition for pultrusion. The impregnation tank temperature is controlled at 25°C. The fiber bundle remains in the impregnation tank for 40 seconds. After excess resin is removed through a preform plate and an extrusion nozzle, it enters a metal pultrusion die. The temperature of the metal pultrusion die is 90°C at the inlet, 130°C in the middle, and 150°C at the outlet. The traction speed is 0.40 m / min. After demolding, it is post-cured in a 120°C hot air channel for 20 minutes. After cooling to below 35°C, it is cut to obtain a lightweight, corrosion-resistant fiberglass profile. The continuous E-glass fiber content in this fiberglass profile is 60%, and the cured phase of the resin composition is the remainder.

[0022] Example 3: The preparation process in this embodiment is the same as that in Example 1, except that: the short-chain high-acid-value phosphate ester-vinyl end-grouped interface-modified oligomer is prepared using 490g of maleic anhydride, 315g of adipic acid, 648g of neopentyl glycol, 152g of 1,2-propanediol, 31g of polyphosphoric acid, and 50g of glycidyl methacrylate. The resulting oligomer has a number-average molecular weight of 1240, an acid value of 16.5mgKOH / g, and a Brookfield viscosity of 1050mPa·s at 25℃; the long-chain low-acid-value phosphate ester-vinyl end-grouped interface-modified oligomer is prepared using 490g of maleic anhydride, 466g of adipic acid, 750g of neopentyl glycol, 152g of 1,2-propanediol, 18g of polyphosphoric acid, and 40g of glycidyl methacrylate. The resulting oligomer has a number-average molecular weight of 1760, an acid value of 8.9mgKOH / g, and a Brookfield viscosity of 1390mPa·s at 25℃.

[0023] Add 100 kg of isophenylene-neopentyl glycol type unsaturated polyester resin and 4.5 kg of styrene to a resin mixing vessel at 25°C, and stir at 300 r / min for 8 min. Add 1.20 kg of short-chain high-acid-value phosphate ester-vinyl end-grouped interface-modified oligomer, and stir at 350 r / min for 15 min. Add 3.5 kg of homologous ground E glass fiber, and disperse at 500 r / min for 18 min. Add 12.0 kg of aluminum hydroxide flame-retardant filler, and disperse at 600 r / min for 25 min. After passing the sample through a 0.30 mm metal sieve, and under stirring at 300 r / min, add long-chain... 1.80 kg of low-acid-value phosphate ester-vinyl-terminated interface-modified oligomer was added dropwise to a resin mixing vessel over 18 min. After the addition was complete, stirring was continued for 15 min. Then, 0.75 kg of zinc stearate and 0.18 kg of polyether-modified defoamer were added, and the mixture was stirred at 300 r / min for 10 min. Finally, 1.50 kg of 50% benzoyl peroxide paste and 0.90 kg of tert-butyl peroxide were added, and the mixture was stirred at 250 r / min for 8 min to obtain an unsaturated polyester resin composition for pultrusion. The resulting composition had a Brookfield viscosity of 884 mPa·s at 25 °C and a gel time of 158 s at 80 °C.

[0024] Continuous E-glass fiber roving is untwisted and spread through a tension frame before entering the impregnation tank of the aforementioned unsaturated polyester resin composition for pultrusion. The impregnation tank temperature is controlled at 25°C, and the fiber bundle remains in the impregnation tank for 40 seconds. After excess resin is removed through a preform plate and an extrusion nozzle, the fiber bundle enters a metal pultrusion die. The temperature of the metal pultrusion die is 100°C at the inlet, 140°C in the middle, and 160°C at the outlet, with a traction speed of 0.30 m / min. After demolding, the fiber bundle is post-cured in a 120°C hot air channel for 20 minutes, cooled to below 35°C, and then cut to obtain a lightweight, corrosion-resistant fiberglass profile. The continuous E-glass fiber content in this fiberglass profile is 62%, and the remaining portion is the cured phase of the resin composition.

[0025] Example 4: The preparation process in this embodiment is the same as that in Example 1, except that: the short-chain high-acid-value phosphate ester-vinyl-terminated interface-modified oligomer is prepared using 490g of maleic anhydride, 285g of adipic acid, 618g of neopentyl glycol, 152g of 1,2-propanediol, 35g of polyphosphoric acid, and 52g of glycidyl methacrylate. The resulting oligomer has a number-average molecular weight of 1080, an acid value of 19.4mgKOH / g, and a Brookfield viscosity of 910mPa·s at 25℃; the long-chain low-acid-value phosphate ester-vinyl-terminated interface-modified oligomer is prepared using 490g of maleic anhydride, 430g of adipic acid, 720g of neopentyl glycol, 152g of 1,2-propanediol, 22g of polyphosphoric acid, and 42g of glycidyl methacrylate. The resulting oligomer has a number-average molecular weight of 1580, an acid value of 11.3mgKOH / g, and a Brookfield viscosity of 1210mPa·s at 25℃.

[0026] 100 kg of isophenylene-neopentyl glycol type unsaturated polyester resin and 4.2 kg of styrene were added to a resin mixing vessel at 25°C and stirred at 300 r / min for 8 min. Then, 0.90 kg of short-chain high-acid-value phosphate ester-vinyl end-modified interface-adjusting oligomer was added and stirred at 350 r / min for 15 min. Next, 2.0 kg of homologous ground E-glass fiber was added and dispersed at 500 r / min for 18 min. Finally, 9.0 kg of aluminum hydroxide flame-retardant filler was added and dispersed at 600 r / min for 25 min. After passing the sample through a 0.30 mm metal sieve, the long-chain low-acid-value phosphate ester was stirred at 300 r / min. 1.50 kg of acid value phosphate ester-vinyl end-grouped interface-modified oligomer was added dropwise to the resin mixing vessel over 18 min. After the addition was complete, stirring was continued for 15 min. Then, 0.62 kg of zinc stearate and 0.14 kg of polyether-modified defoamer were added, and the mixture was stirred at 300 r / min for 10 min. Finally, 1.25 kg of 50% benzoyl peroxide paste and 0.70 kg of tert-butyl peroxide were added, and the mixture was stirred at 250 r / min for 8 min to obtain an unsaturated polyester resin composition for pultrusion. The resulting composition had a Brookfield viscosity of 752 mPa·s at 25 °C and a gel time of 171 s at 80 °C.

[0027] Continuous E-glass fiber roving is untwisted and spread through a tension frame before entering the impregnation tank of the aforementioned unsaturated polyester resin composition for pultrusion. The impregnation tank temperature is controlled at 25°C. The fiber bundle remains in the impregnation tank for 40 seconds. After excess resin is removed through a preform plate and an extrusion nozzle, it enters a metal pultrusion die. The temperature of the metal pultrusion die is 95°C at the inlet, 132°C in the middle, and 155°C at the outlet. The traction speed is 0.38 m / min. After demolding, it is post-cured in a 120°C hot air channel for 20 minutes. After cooling to below 35°C, it is cut to obtain a lightweight, corrosion-resistant fiberglass profile. The continuous E-glass fiber content in this fiberglass profile is 61%, and the cured phase of the resin composition is the balance.

[0028] Example 5: The preparation process in this embodiment is the same as that in Example 1, except that: the short-chain high-acid-value phosphate ester-vinyl-terminated interface-modified oligomer is prepared using 490g of maleic anhydride, 300g of adipic acid, 630g of neopentyl glycol, 152g of 1,2-propanediol, 33g of polyphosphoric acid, and 51g of glycidyl methacrylate. The resulting oligomer has a number-average molecular weight of 1160, an acid value of 17.9mgKOH / g, and a Brookfield viscosity of 980mPa·s at 25℃; the long-chain low-acid-value phosphate ester-vinyl-terminated interface-modified oligomer is prepared using 490g of maleic anhydride, 450g of adipic acid, 735g of neopentyl glycol, 152g of 1,2-propanediol, 19g of polyphosphoric acid, and 41g of glycidyl methacrylate. The resulting oligomer has a number-average molecular weight of 1680, an acid value of 10.1mgKOH / g, and a Brookfield viscosity of 1310mPa·s at 25℃.

[0029] Add 100 kg of isophenylene-neopentyl glycol type unsaturated polyester resin and 4.3 kg of styrene to a resin mixing vessel at 25°C, and stir at 300 r / min for 8 min. Add 0.65 kg of short-chain high-acid-value phosphate ester-vinyl end-grouped interface-modified oligomer, and stir at 350 r / min for 15 min. Add 3.0 kg of homologous ground E glass fiber, and disperse at 500 r / min for 18 min. Add 11.0 kg of aluminum hydroxide flame-retardant filler, and disperse at 600 r / min for 25 min. After passing the sample through a 0.30 mm metal sieve, and under stirring at 300 r / min, add long-chain... 1.25 kg of low-acid-value phosphate ester-vinyl-terminated interface-modified oligomer was added dropwise to a resin mixing vessel over 18 min. After the addition was complete, stirring was continued for 15 min. Then, 0.68 kg of zinc stearate and 0.16 kg of polyether-modified defoamer were added, and the mixture was stirred at 300 r / min for 10 min. Finally, 1.35 kg of 50% benzoyl peroxide paste and 0.80 kg of tert-butyl peroxide were added, and the mixture was stirred at 250 r / min for 8 min to obtain an unsaturated polyester resin composition for pultrusion. The resulting composition had a Brookfield viscosity of 820 mPa·s at 25 °C and a gel time of 166 s at 80 °C.

[0030] Continuous E-glass fiber roving is untwisted and spread through a tension frame before entering the impregnation tank of the aforementioned unsaturated polyester resin composition for pultrusion. The impregnation tank temperature is controlled at 25°C. The fiber bundle remains in the impregnation tank for 40 seconds. After excess resin is removed through a preform plate and an extrusion nozzle, it enters a metal pultrusion die. The temperature of the metal pultrusion die is 98°C at the inlet, 138°C in the middle, and 158°C at the outlet. The traction speed is 0.34 m / min. After demolding, it is post-cured in a 120°C hot air channel for 20 minutes. After cooling to below 35°C, it is cut to obtain a lightweight, corrosion-resistant fiberglass profile. The continuous E-glass fiber content in this fiberglass profile is 62%, and the cured phase of the resin composition is the balance.

[0031] Comparative Example 1: This comparative example differs from Example 1 in that it does not include short-chain and long-chain phosphate ester-vinyl end-modified interface-regulating oligomers, but instead uses an equal amount of 2.10 kg of isophenylene-neopentyl glycol type unsaturated polyester resin to make up the difference. All other conditions are the same as in Example 1.

[0032] Comparative Example 2: The difference between this comparative example and Example 1 is that the total amount of short-chain and long-chain interface-modified oligomers was reduced to 0.50 kg, of which 0.18 kg were short-chain and 0.32 kg were long-chain, and the remainder was made up with an equal amount of 1.60 kg of isophenylene-neopentyl glycol type unsaturated polyester resin. All other conditions were the same as in Example 1.

[0033] Comparative Example 3: The difference between this comparative example and Example 1 is that the total amount of short-chain and long-chain interface-modifying oligomers was increased to 4.50 kg, of which 1.60 kg were short-chain and 2.90 kg were long-chain. At the same time, the amount of isophenylene-neopentyl glycol type unsaturated polyester resin was reduced to 97.60 kg to keep the total amount of resin composition unchanged. All other conditions were the same as in Example 1.

[0034] Comparative Example 4: The difference between this comparative example and Example 1 is that 0.75 kg of short-chain filler and 1.35 kg of long-chain filler were added all at once after the aluminum hydroxide flame retardant filler was dispersed, instead of the order of dispersing the short-chain filler first and then adding the long-chain filler dropwise. All other conditions were the same as in Example 1.

[0035] Comparative Example 5: This comparative example differs from Example 1 in that it does not contain homologous ground E-glass fiber, but is made up with an equal amount of 2.50 kg of isophenylene-neopentyl glycol type unsaturated polyester resin. All other conditions are the same as in Example 1.

[0036] Comparative Example 6: The difference between this comparative example and Example 1 is that the pultrusion die temperature was changed from 95℃, 135℃, 155℃ to a single-segment constant temperature of 110℃, 110℃, 110℃, while the traction speed remained at 0.36m / min. All other conditions were the same as in Example 1.

[0037] Comparative Example 7: This comparative example differs from Example 1 in that 0.75 kg of tert-butyl peroxide was not added, and the amount was made up with an equal amount of 0.75 kg of isophenylene-neopentyl glycol type unsaturated polyester resin. All other conditions were the same as in Example 1.

[0038] Comparative Example 8: The difference between this comparative example and Example 1 is that glycidyl methacrylate was not added during the preparation of the terminally terminal interface-modified oligomer, resulting in an unvinyl-terminated phosphate ester interface-modified oligomer; the amount and order of addition of short and long chains were the same as in Example 1. All other conditions were the same as in Example 1.

[0039] Performance testing Resin composition viscosity and gel time at 80°C: Take 500 mL of the unsaturated polyester resin composition for pultrusion prepared in each example and comparative example but not yet placed in the impregnation tank, and test the Brookfield viscosity at 25°C according to GB / T 7193-2008. Use a Brookfield DV2T rotational viscometer, rotor No. 4, 60 r / min. Each sample is measured in parallel 3 times, and the arithmetic mean is taken. Take another 50.0 g sample and place it in an 80°C constant temperature water bath. Use a gel time measuring device to record the time from when the sample is placed in the water bath until it loses its fluidity. Each sample is measured in parallel 3 times, and the results are recorded in seconds.

[0040] Density: Pultruded profiles cured at 120℃ for 20 min were cut into 25mm×25mm×6mm specimens. Density was tested using the buoyancy method according to GB / T 1463-2005. Before testing, the specimens were conditioned for 24 hours at 23℃ and 50% relative humidity. Five specimens were used for each test, and the average value was taken. The unit is g / cm³. 3 .

[0041] Barcol hardness: After grinding the flat surface of the profile to be free of burrs, test it using a 934-1 type Barcol hardness tester according to GB / T 3854-2017. Test 10 points on each sample, with a test point spacing of not less than 10mm. Remove obvious edge defects. Test 3 pieces for each sample, and take the average of all valid readings.

[0042] Bending strength: The profile was cut into 120mm×15mm×6mm bending specimens along the pultrusion direction. Three-point bending test was performed according to GB / T 1449-2005, with a span of 96mm and a loading speed of 5mm / min. The specimens were conditioned for 24h at 23℃ and 50% relative humidity. Five specimens were used for each test. The maximum load was recorded and the bending strength was calculated in MPa.

[0043] Oxygen Index: The profile was cut into strips of 80mm×10mm×4mm and tested using an oxygen index tester according to GB / T 8924-2005. The samples were conditioned for 48 hours at 23℃ and 50% relative humidity. At least 15 samples were tested for each sample. The minimum oxygen concentration that just sustains combustion was determined by the rise and fall method. The results were recorded as %

[0044] Acid and alkali resistance test: A bending specimen of the same dimensions as the one used in the bending strength test was dried at 50°C for 24 hours before immersion and weighed (m0). The specimen was then placed in a 10% H₂SO₄ aqueous solution and a 5% NaOH aqueous solution, respectively, with the liquid volume to specimen surface area ratio not less than 20 mL / cm². 2 The samples were soaked at 23℃ for 168 hours. After removal, they were rinsed with deionized water for 30 seconds, blotted dry with absorbent paper for 60 seconds, and weighed within 5 minutes (m1). The weight gain rate was calculated as (m1-m0) / m0 × 100%. Subsequently, the bending strength after soaking was tested according to GB / T 1449-2005, and the bending strength retention rate was calculated as (bending strength after soaking / bending strength of the same batch without soaking) × 100%. Five samples were used for each medium, and the average value was taken.

[0045] Table 1 Basic Performance Test Results Table 2 Test results of acid and alkali resistance performance Data Analysis: As shown in Tables 1 and 2, the viscosity of the fiberglass profiles obtained in Examples 1-5 at 25℃ is 665-884 mPa·s, and the gel time at 80℃ is 158-187 s, both within the operable window of continuous pultrusion wetting and curing. The weight gain after soaking in 10% H2SO4 for 168 h is 0.41%-0.53%, and the flexural strength retention rate is 84.1%-89.2%. The weight gain after soaking in 5% NaOH for 168 h is 0.48%-0.60%, and the flexural strength retention rate is 82.4%-87.6%.

[0046] Compared with Comparative Example 1 (without phosphate ester-vinyl end-modified interface-modified oligomers), Comparative Example 2 (total oligomers below the window), and Comparative Example 3 (total oligomers above the window), under the condition of supplementing with an equal amount of isophenylene-neopentyl glycol type unsaturated polyester resin and keeping the total amount of resin composition basically the same, the examples showed lower weight gain and higher flexural strength retention after acid and alkali immersion, indicating that the molecular weight, acid value, and addition amount window of the interface-modified oligomers are related to the strength retention after media resistance.

[0047] Compared to Comparative Example 4, which added both short-chain and long-chain oligomers in one step, Examples 1 and 4 showed higher media retention rates, indicating that adding the short-chain oligomers first and then the long-chain oligomers was beneficial for improving the wetting and pre-curing state. Compared to Comparative Example 5, which did not add ground E-glass fibers, Example 1 showed improved initial flexural strength and post-immersion retention rates, indicating that the combined use of homologous ground E-glass fibers and the interface-modifying oligomers was beneficial for improving local filling and interfacial continuity.

[0048] Comparative Examples 6 and 7 deviated from the three-stage mold temperature curing window and the composite curing system, respectively, resulting in a decrease in their Barcol hardness, flexural strength, and media resistance retention rate. This indicates that matching the pultrusion curing window with the resin composition has an impact on the final profile performance. In summary, the present invention improves the flexural strength retention rate after acid and alkali immersion while maintaining a low density and oxygen index level, making it suitable for lightweight, corrosion-resistant fiberglass pultruded profiles.

[0049] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

Claims

1. A lightweight, corrosion-resistant fiberglass profile, characterized in that, It comprises a continuous E-glass fiber and a cured resin composition; based on the total mass of the lightweight corrosion-resistant fiberglass profile, the content of the continuous E-glass fiber is 60%-62%, and the balance is the cured resin composition; The cured resin composition is formed by curing an unsaturated polyester resin composition for pultrusion. Based on 100 parts by weight of isophenylene-neopentyl glycol type unsaturated polyester resin, the unsaturated polyester resin composition for pultrusion comprises: 3.8-4.5 parts by weight of styrene, 1.2-3.0 parts by weight of phosphate ester-vinyl end-modified interface-modified oligomer, 1.5-3.5 parts by weight of ground E glass fiber, 8-12 parts by weight of aluminum hydroxide flame retardant filler, 0.55-0.75 parts by weight of zinc stearate, 0.12-0.18 parts by weight of polyether modified defoamer, 1.10-1.50 parts by weight of 50% benzoyl peroxide paste, and 0.60-0.90 parts by weight of tert-butyl peroxide. The phosphate ester-vinyl end-modified interface-regulating oligomers are prepared by reacting hydroxyl-terminated unsaturated polyester oligomers, polyphosphoric acid, and glycidyl methacrylate, and include short-chain high-acid-value phosphate ester-vinyl end-modified interface-regulating oligomers and long-chain low-acid-value phosphate ester-vinyl end-modified interface-regulating oligomers. The number-average molecular weight of the short-chain high-acid-value phosphate ester-vinyl end-modified interface-regulating oligomers is 950-1250, and the acid value is 16-22 mgKOH / g. The number-average molecular weight of the long-chain low-acid-value phosphate ester-vinyl end-modified interface-regulating oligomers is 1400-1800, and the acid value is 8-14 mgKOH / g. The mass ratio of the short-chain high-acid-value phosphate ester-vinyl end-modified interface-regulating oligomers to the long-chain low-acid-value phosphate ester-vinyl end-modified interface-regulating oligomers is 1:(1.5-1.9).

2. The lightweight corrosion-resistant fiberglass profile according to claim 1, characterized in that, The average length of the ground E glass fiber is 45-90 μm, and the moisture content is no more than 0.10%.

3. The lightweight corrosion-resistant fiberglass profile according to claim 1, characterized in that, The median particle size of the aluminum hydroxide flame retardant filler is 8-10 μm; the isophenylene-neopentyl glycol type unsaturated polyester resin has a Brookfield viscosity of 520-620 mPa·s at 25°C, an acid value of 18-23 mgKOH / g, and a solid content of 62%-66%.

4. The lightweight corrosion-resistant fiberglass profile according to claim 1, characterized in that, The continuous E glass fiber is an untwisted roving of E glass fiber with a linear density of 2400 tex.

5. The lightweight corrosion-resistant fiberglass profile according to claim 1, characterized in that, The unsaturated polyester resin composition for pultrusion has a Brinell viscosity of 650-900 mPa·s measured at 25°C, rotor No. 4, and 60 r / min, and a gel time of 155-190 s measured at 80°C; the lightweight corrosion-resistant fiberglass profile has a density of 1.69-1.76 g / cm³ tested according to GB / T 1463-2005.

6. A method for preparing a lightweight corrosion-resistant fiberglass profile according to any one of claims 1-5, characterized in that, Includes the following steps: The phosphate ester-vinyl end-modified interface-controlled oligomer was prepared by mixing isophenylene-neopentyl glycol type unsaturated polyester resin and styrene, adding short-chain high-acid-value phosphate ester-vinyl end-modified interface-controlled oligomer and stirring, adding ground E glass fiber for dispersion, then adding aluminum hydroxide flame retardant filler for dispersion, followed by dropwise addition of long-chain low-acid-value phosphate ester-vinyl end-modified interface-controlled oligomer, zinc stearate, polyether modified defoamer, 50% benzoyl peroxide paste and tert-butyl peroxide to obtain an unsaturated polyester resin composition for pultrusion; continuous E glass fiber was impregnated with the unsaturated polyester resin composition for pultrusion and then cured in a pultrusion mold.

7. The preparation method according to claim 6, characterized in that, In preparing the phosphate ester-vinyl-terminated interface-modified oligomer, maleic anhydride, adipic acid, neopentyl glycol and 1,2-propanediol are first subjected to a polycondensation reaction under nitrogen protection to obtain hydroxyl-terminated unsaturated polyester oligomers. Then, the hydroxyl-terminated unsaturated polyester oligomers are reacted with polyphosphoric acid at 80-84°C. Subsequently, glycidyl methacrylate is added dropwise and the mixture is kept at 84°C for 130-150 min.

8. The preparation method according to claim 6, characterized in that, The ground E-glass fiber is added after the short-chain high-acid-value phosphate ester-vinyl end-grouping interface-modified oligomer is added and before the aluminum hydroxide flame-retardant filler is added, and dispersed at 450-550 r / min for 15-20 min.

9. The preparation method according to claim 6, characterized in that, The long-chain, low-acid-value phosphate ester-vinyl-terminated interface-modified oligomer is added dropwise after the aluminum hydroxide flame-retardant filler is dispersed, and before the addition of the 50% benzoyl peroxide paste and the tert-butyl peroxide, with a dropwise addition time of 15-20 minutes.

10. The preparation method according to claim 6, characterized in that, The pultrusion die includes an inlet section, a middle section, and an outlet section. The temperature of the inlet section is 90-100℃, the temperature of the middle section is 130-140℃, and the temperature of the outlet section is 150-160℃. The traction speed is 0.30-0.40m / min. After demolding, it is post-cured in a 120℃ hot air channel for 20 minutes.

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