Preparation method of impact-resistant and heat-resistant polyester resin

Abstract

The invention discloses a preparation method of impact-resistant and heat-resistant polyester resin. The preparation method comprises the following steps: S1, material pretreatment; s2, synthesizing a polyester prepolymer; s3, mixing and preparing nano silicon; s4, polycondensation reaction; and S5, cooling, diluting and post-processing. The nano silicon particles are polymerized in the polyester resin, and the nano particles fill resin micropores, initiate crack deflection and bridging and block a crack propagation path, so that a matrix is strengthened, the impact resistance and deformation resistance of the material are effectively improved, and compared with traditional unsaturated polyester resin, after nano silicon modification, the impact resistance and deformation resistance of the material are improved, and the impact resistance and deformation resistance of the material are improved. The thermal decomposition temperature of the resin can be increased by 20-50 DEG C, so that high-temperature degradation is delayed, meanwhile, nano silicon is migrated to the surface of the material during combustion, a compact silicate barrier is formed, heat and oxygen are blocked, and the combustion rate is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of polyester resins, in particular to a method for preparing an impact-resistant and heat-resistant polyester resin. Background Art

[0002] Polyester resin is a general term for polymer compounds formed by the polycondensation of diols, dibasic acids, or polyols and polyacids. Polyester resins are divided into saturated polyester resins and unsaturated polyester resins. Unsaturated polyester adhesives are primarily composed of unsaturated polyester resins, pigments, fillers, initiators, and other additives. The adhesive has low viscosity, is easily wettable, and has excellent processability. The cured adhesive layer exhibits high hardness, good transparency, high brightness, rapid curing under pressure at room temperature, good heat resistance, and excellent electrical properties. However, its disadvantages are high shrinkage, low adhesive toughness, and poor chemical and water resistance. It is used in non-structural adhesives. It is primarily used for bonding fiberglass, rigid plastics, concrete, and electrical can seals.

[0003] Currently available

[0004] Therefore, we propose to design a method for preparing an impact-resistant and heat-resistant polyester resin. Summary of the Invention

[0005] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of this application to avoid blurring the purpose of this section, the abstract and the title of the invention, and such simplifications or omissions should not be used to limit the scope of the present invention.

[0006] To solve the above technical problems, according to one aspect of the present invention, the present invention provides the following technical solutions:

[0007] A method for preparing an impact-resistant and heat-resistant polyester resin comprises the following steps:

[0008] S1. Material pretreatment

[0009] S1.1 Weigh 20g of fumed nanosilica and place it in a beaker. Add 100g of anhydrous toluene and ultrasonically disperse the mixture at 400W for 30 minutes to obtain a nanosilica suspension.

[0010] S1.2 Add 2 g of KH-570 silane coupling agent to the nano-silicon suspension, place the beaker on a constant temperature magnetic stirrer, install a reflux condenser, introduce nitrogen, gradually raise the temperature to 80°C, and maintain the temperature for 3 h with vigorous stirring;

[0011] After the reaction is completed, transfer the nanosilicon suspension to a rotary evaporator and place it in a water bath at 60°C. Remove the toluene solvent by vacuum distillation until dry and loose KH-570 modified nanosilica powder is obtained. The modified nanosilica powder is sealed and stored.

[0012] S2, synthetic polyester prepolymer

[0013] S2.1 Assemble a 2 L four-necked flask and install a paddle stirrer, thermowell, water trap, reflux condenser, and nitrogen inlet on top. Add 330 g of phthalic anhydride, 200 g of maleic anhydride, and 380 g of propylene glycol to the flask. Simultaneously, add 0.5 g of tetrabutyl titanate as a catalyst and 0.05 g of hydroquinone as a polymerization inhibitor.

[0014] S2.2 Start stirring with a paddle stirrer at 100 rpm and slowly increase the temperature to 150°C;

[0015] S2.3 Raise the temperature to 180-190°C and maintain the temperature. Distill the generated water through a water separator and collect it. Record the amount of water produced. Adjust the stirring speed to 200-300 rpm and continue to introduce a steady stream of nitrogen.

[0016] S2.4 Take samples regularly and measure the acid value after cooling. When the acid value drops to 45±5 mg KOH / g, the esterification stage is completed and a slightly yellow, transparent, viscous prepolymer melt is obtained.

[0017] S3. Nano-silicon mixed preparation

[0018] S3.1 Lower the reaction temperature to 160-165°C and add 20g of pre-made KH-570 modified nano-silica powder while continuing to flow nitrogen and stirring at 200 rpm.

[0019] S3.2 After all the nano-silicon is added, immediately insert the rotor-stator head of the high-speed disperser into the molten prepolymer, turn on the high-speed disperser, and strongly shear and disperse at a speed of 8000-10000 rpm for 15 minutes;

[0020] S4. Polycondensation

[0021] S4.1 Remove the disperser and ultrasonic probe, slowly raise the temperature of the reaction system to 190-200°C, continue to introduce nitrogen protection, and continue stirring at 200-300 rpm;

[0022] S4.2 Close the nitrogen inlet pipe, while maintaining a small amount of nitrogen flow at the upper end of the condenser. Turn on the vacuum pump and gradually increase the vacuum level in stages:

[0023] Stage 1: Pump down to -0.05 MPa and maintain for 15 minutes;

[0024] Stage 2: Pump down to -0.08 MPa and maintain for 15 minutes;

[0025] Stage 3: Pumping to -0.095MPa;

[0026] S4.3 In a high vacuum environment of -0.095 MPa, the heating temperature was maintained at 200°C and the reaction continued;

[0027] S4.4 Continuously measure the acid value. The polycondensation reaction is complete when the acid value drops to 18 ± 2 mg KOH / g and the melt becomes very viscous, the stirring current increases significantly, or a thin, easily broken thread can be drawn out after the sample is cooled.

[0028] S5. Cooling, dilution and post-processing

[0029] S5.1 Slowly turn off the vacuum pump, introduce nitrogen into the reactor to atmospheric pressure, stop heating, remove the reactor from the heat source, keep stirring, and allow the molten prepolymer to cool naturally to 90-100°C;

[0030] S5.2 Once completely cooled to a stable temperature of 90-100°C, slowly and steadily add 360 g of styrene while stirring continuously at 150-200 rpm under nitrogen protection. Continue stirring for 30-60 minutes until a uniform, transparent or slightly yellowish viscous liquid is formed.

[0031] S5.3 Filter the resin through a 200-300 mesh stainless steel filter at 60-80°C;

[0032] S5.4 Transfer the filtered resin to a sealed container, continue cooling to room temperature, and then refrigerate at 4-8°C.

[0033] As a preferred embodiment of the method for preparing an impact-resistant and heat-resistant polyester resin according to the present invention, in S1, the ultrasonic crusher is a probe-type ultrasonic crusher, and the ultrasonic crusher pauses for 5 seconds every 10 seconds during ultrasonication, thereby preventing the ultrasonic suspension from overheating and facilitating the acquisition of a uniform nano-silicon suspension.

[0034] As a preferred embodiment of the method for preparing an impact-resistant and heat-resistant polyester resin according to the present invention, in S2, when the paddle stirrer is stirring, a stable nitrogen flow is introduced through the nitrogen inlet pipe for 15 minutes at a flow rate of 50 ml / min to facilitate the discharge of air in the reactor.

[0035] As a preferred embodiment of the method for preparing an impact-resistant and heat-resistant polyester resin according to the present invention, in S2, the method for determining the acid value is titration with a KOH / ethanol solution, so as to determine whether the esterification reaction is completed.

[0036] As a preferred embodiment of the method for preparing an impact-resistant and heat-resistant polyester resin according to the present invention, in S3, the KH-570 modified nano-silica powder is added slowly in batches to prevent agglomeration caused by adding too quickly.

[0037] As a preferred embodiment of the method for preparing an impact-resistant and heat-resistant polyester resin according to the present invention, in S3, during the shear dispersion, a probe-type ultrasonic crusher is used at intervals with a power of 300 W, on for 5 seconds, off for 5 seconds, and dispersion for 5 minutes, and the dispersion temperature is not higher than 170°C, to facilitate auxiliary shear dispersion.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] The present invention polymerizes nano-silicon particles in polyester resin. The nano-particles fill the resin micropores, induce crack deflection and bridging, and block the crack propagation path, thereby strengthening the matrix and effectively improving the material's impact resistance and deformation resistance. Compared with traditional unsaturated polyester resins, after nano-silicon modification, the resin's thermal decomposition temperature can be increased by 20-50°C, thereby delaying high-temperature degradation. At the same time, nano-silicon migrates to the material surface during combustion, forming a dense silicate barrier, blocking heat and oxygen, and reducing the combustion rate. DETAILED DESCRIPTION

[0040] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below.

[0041] The present invention provides a method for preparing an impact-resistant and heat-resistant polyester resin, comprising the following steps:

[0042] S1. Material pretreatment

[0043] S1.1 Weigh 20g of fumed nanosilica and place it in a beaker. Add 100g of anhydrous toluene and ultrasonically disperse the mixture at 400W for 30 minutes to obtain a nanosilica suspension.

[0044] S1.2 Add 2g KH-570 silane coupling agent to the nano-silicon suspension, place the beaker on a constant temperature magnetic stirrer, install a reflux condenser, introduce nitrogen, gradually raise the temperature to 80°C, and keep warm for 3 hours under strong stirring to facilitate the hydrolysis of KH-570 and condensation with the hydroxyl groups on the surface of the nano-silicon.

[0045] After the reaction in step S1.3 is completed, the nano-silicon suspension is transferred to a rotary evaporator and placed in a water bath at a temperature of 60°C. The toluene solvent is removed by vacuum distillation until dry and loose KH-570 modified nano-silica powder is obtained. The modified nano-silica powder is sealed and stored.

[0046] The ultrasonic crusher is a probe-type ultrasonic crusher. During ultrasonication, the ultrasonic crusher pauses for 5 seconds every 10 seconds to prevent the ultrasonic suspension from overheating, so as to obtain a uniform nano-silicon suspension.

[0047] S2, synthetic polyester prepolymer

[0048] S2.1 Assemble a 2 L four-necked flask and install a paddle stirrer, thermowell, water trap, reflux condenser, and nitrogen inlet on top. Add 330 g of phthalic anhydride, 200 g of maleic anhydride, and 380 g of propylene glycol to the flask. Simultaneously, add 0.5 g of tetrabutyl titanate as a catalyst and 0.05 g of hydroquinone as a polymerization inhibitor.

[0049] S2.2 Start stirring with a paddle stirrer at 100 rpm and slowly increase the temperature to 150°C;

[0050] S2.3 Raise the temperature to 180-190°C and maintain the temperature. Distill the generated water through a water separator and collect it. Record the amount of water produced. Adjust the stirring speed to 200-300 rpm and continue to introduce a steady stream of nitrogen.

[0051] S2.4 Take samples regularly and measure the acid value after cooling. When the acid value drops to 45±5 mg KOH / g, the esterification stage is completed and a slightly yellow, transparent, viscous prepolymer melt is obtained. Alternatively, after a reaction time of 4-6 hours, the reaction is completed and a polyester prepolymer melt is obtained.

[0052] While stirring with a paddle stirrer, a steady flow of nitrogen was introduced through the nitrogen inlet tube for 15 min at a flow rate of 50 ml / min to facilitate exhausting the air in the reactor.

[0053] In this embodiment, the acid value is determined by titration with a KOH / ethanol solution, so as to determine whether the esterification reaction is complete.

[0054] S3. Nano-silicon mixed preparation

[0055] S3.1 Lower the reaction temperature to 160-165°C to prevent excessive temperature from damaging silane bonds or causing nano-silicon sintering. While continuing to flow nitrogen and stirring at 200 rpm, add 20g of pre-made KH-570 modified nano-silica powder.

[0056] S3.2 After adding nano silicon, immediately insert the rotor-stator head of the high-speed disperser into the molten prepolymer, turn on the high-speed disperser, and strongly shear and disperse at a speed of 8000-10000rpm for 15 minutes to ensure that the nano silicon is evenly dispersed and prevent agglomeration.

[0057] KH-570 modified nano-silica powder should be added slowly in batches to prevent agglomeration caused by adding too quickly.

[0058] During the shear dispersion, a probe-type ultrasonic crusher is used intermittently with a power of 300W, 5 seconds on, 5 seconds off, and 5 minutes of dispersion. The dispersion temperature is not higher than 170°C to assist in shear dispersion.

[0059] S4. Polycondensation

[0060] S4.1 Remove the disperser and ultrasonic probe, slowly raise the temperature of the reaction system to 190-200°C, continue to introduce nitrogen protection, and continue stirring at 200-300 rpm;

[0061] S4.2 Close the nitrogen inlet pipe, while maintaining a small amount of nitrogen flow at the upper end of the condenser. Turn on the vacuum pump and gradually increase the vacuum level in stages:

[0062] Stage 1: Pump down to -0.05 MPa and maintain for 15 minutes;

[0063] Stage 2: Pump down to -0.08 MPa and maintain for 15 minutes;

[0064] Stage 3: Pumping to -0.095MPa;

[0065] S4.3 In a high vacuum environment of -0.095 MPa, the heating temperature was maintained at 200°C and the reaction continued;

[0066] S4.4 Continuously measure the acid value. The polycondensation reaction is complete when the acid value drops to 18 ± 2 mg KOH / g and the melt becomes very viscous, the stirring current increases significantly, or a thin, easily broken thread can be drawn out after the sample is cooled.

[0067] S5. Cooling, dilution and post-processing

[0068] S5.1 Slowly turn off the vacuum pump, introduce nitrogen into the reactor to atmospheric pressure, stop heating, remove the reactor from the heat source, keep stirring, and allow the molten prepolymer to cool naturally to 90-100°C;

[0069] S5.2 When the temperature is completely cooled to 90-100℃, and the stirring is continued at 150-200rpm and nitrogen protection, 360g of styrene is slowly and steadily added, after the addition, continue to stir for 30-60min, until a uniform, transparent or yellowish viscous liquid is formed;

[0070] S5.3 The resin is filtered at 60-80℃ through a 200-300 mesh stainless steel filter screen to remove possible gel particles or not completely dispersed aggregates.

[0071] S5.4 The filtered resin is transferred to a sealed container, and continue to cool to room temperature, and then stored in a cold environment at 4-8℃.

[0072] Compared with the traditional polyester resin, the present application:

[0073] In the mechanical property comparison, the addition of 0.5% nano-silicon dioxide can make the tensile strength of unsaturated polyester resin increase by 30.45%, the compression strength increase by 33%, and the bending strength increase by 17.8%, effectively improving the impact resistance and deformation resistance of polyester resin.

[0074] Specifically referring to the research results of Addis Ababa University in Ethiopia, the improvement effect of nano-silicon dioxide on bending strength and impact strength is better than that of nano-montmorillonite.

[0075] In the thermal performance comparison, the modification of organic silicon can significantly improve the heat resistance of the resin. The ordinary unsaturated polyester can only be used below 155℃, while the modified heat resistance is significantly improved. TGA analysis also shows that the nano-silicon modified resin has better thermal stability.

[0076] Although the present application has been described with reference to the embodiments above, various modifications can be made thereto without departing from the scope of the present application. Each feature disclosed in the embodiments of the present application can be used in any combination with each other feature disclosed in the embodiments of the present application. The combinations of features described in the specification are not exhaustive and are only provided for the purpose of omitting the length of the description and saving resources. Therefore, the present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for preparing an impact-resistant and heat-resistant polyester resin, characterized in that: The steps include: S1. Material pretreatment S1.1 Weigh 20g of fumed nanosilica and place it in a beaker. Add 100g of anhydrous toluene and ultrasonically disperse the mixture at 400W for 30 minutes to obtain a nanosilica suspension. S1.2 Add 2 g of KH-570 silane coupling agent to the nano-silicon suspension, place the beaker on a constant temperature magnetic stirrer, install a reflux condenser, introduce nitrogen, gradually raise the temperature to 80°C, and maintain the temperature for 3 h with vigorous stirring; After the reaction is completed, transfer the nanosilicon suspension to a rotary evaporator and place it in a water bath at 60°C. Remove the toluene solvent by vacuum distillation until dry and loose KH-570 modified nanosilica powder is obtained. The modified nanosilica powder is sealed and stored. S2, synthetic polyester prepolymer S2.1 Assemble a 2 L four-necked flask and install a paddle stirrer, thermowell, water trap, reflux condenser, and nitrogen inlet on top. Add 330 g of phthalic anhydride, 200 g of maleic anhydride, and 380 g of propylene glycol to the flask. Simultaneously, add 0.5 g of tetrabutyl titanate as a catalyst and 0.05 g of hydroquinone as a polymerization inhibitor. S2.2 Start stirring with a paddle stirrer at 100 rpm and slowly increase the temperature to 150°C; S2.3 Raise the temperature to 180-190°C and maintain the temperature. Distill the generated water through a water separator and collect it. Record the amount of water produced. Adjust the stirring speed to 200-300 rpm and continue to introduce a steady stream of nitrogen. S2.4 Take samples regularly and measure the acid value after cooling. When the acid value drops to 45±5 mg KOH / g, the esterification stage is completed and a slightly yellow, transparent, viscous prepolymer melt is obtained. S3. Nano-silicon mixed preparation S3.1 Lower the reaction temperature to 160-165°C and add 20g of pre-made KH-570 modified nano-silica powder while continuing to flow nitrogen and stirring at 200 rpm. S3.2 After all the nano-silicon is added, immediately insert the rotor-stator head of the high-speed disperser into the molten prepolymer, turn on the high-speed disperser, and strongly shear and disperse at a speed of 8000-10000 rpm for 15 minutes; S4. Polycondensation S4.1 Remove the disperser and ultrasonic probe, slowly raise the temperature of the reaction system to 190-200°C, continue to introduce nitrogen protection, and continue stirring at 200-300 rpm; S4.2 Close the nitrogen inlet pipe, while maintaining a small amount of nitrogen flow at the upper end of the condenser. Turn on the vacuum pump and gradually increase the vacuum level in stages: Stage 1: Pump down to -0.05 MPa and maintain for 15 minutes; Stage 2: Pump down to -0.08 MPa and maintain for 15 minutes; Stage 3: Pumping to -0.095MPa; S4.3 In a high vacuum environment of -0.095 MPa, the heating temperature was maintained at 200°C and the reaction continued; S4.4 Continuously measure the acid value. The polycondensation reaction is complete when the acid value drops to 18 ± 2 mg KOH / g and the melt becomes very viscous, the stirring current increases significantly, or a thin, easily broken thread can be drawn out after the sample is cooled. S5. Cooling, dilution and post-processing S5.1 Slowly turn off the vacuum pump, introduce nitrogen into the reactor to atmospheric pressure, stop heating, remove the reactor from the heat source, keep stirring, and allow the molten prepolymer to cool naturally to 90-100°C; S5.2 Once completely cooled to a stable temperature of 90-100°C, slowly and steadily add 360 g of styrene while stirring continuously at 150-200 rpm under nitrogen protection. Continue stirring for 30-60 minutes until a uniform, transparent or slightly yellowish viscous liquid is formed. S5.3 Filter the resin through a 200-300 mesh stainless steel filter at 60-80°C; S5.4 Transfer the filtered resin to a sealed container, continue cooling to room temperature, and then refrigerate at 4-8°C.

2. The method for preparing an impact-resistant and heat-resistant polyester resin according to claim 1, wherein: In S1, the ultrasonic crusher is a probe-type ultrasonic crusher, and the ultrasonic crusher pauses for 5 seconds every 10 seconds during ultrasonication.

3. The method for preparing an impact-resistant and heat-resistant polyester resin according to claim 1, wherein: In S2, while stirring with the paddle stirrer, a steady flow of nitrogen gas was introduced through the nitrogen inlet tube for 15 minutes at a flow rate of 50 ml / min.

4. The method for preparing an impact-resistant and heat-resistant polyester resin according to claim 1, wherein: In S2, the method for determining the acid value is titration with KOH / ethanol solution.

5. The method for preparing an impact-resistant and heat-resistant polyester resin according to claim 1, wherein: In S3, the KH-570 modified nano-silicon dioxide powder is slowly added in batches.

6. The method for preparing an impact-resistant and heat-resistant polyester resin according to claim 1, wherein: In the above S3, during the shear dispersion, a probe-type ultrasonic crusher was used at intervals with a power of 300 W, with a cycle of 5 seconds on and 5 seconds off for 5 minutes of dispersion, and the dispersion temperature was no higher than 170°C.