Polyester composition as well as preparation method and application thereof

Abstract

The invention relates to a polyester composition as well as a preparation method and application thereof, and belongs to the technical field of high-molecular compound compositions. The polyester composition disclosed by the invention is prepared from the following components in parts by weight: 50 to 90 parts of polyester resin, 0.2 to 3 parts of nano filler and 5 to 40 parts of glass fiber, the polyester resin comprises polybutylene terephthalate and / or polyethylene glycol terephthalate; the nano filler comprises nano particles and nano fibers; the degree of sphericity of the nanoparticles is 0.9-1; the particle sizes D10, D50 and D90 of the nanoparticles meet the condition that (D90-D10) / D50 is less than or equal to 1.3. The polyester composition has good low-temperature toughness, heat resistance and low-temperature cracking resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high molecular compound compositions, in particular to a polyester composition and a preparation method and application thereof. BACKGROUND

[0002] Polybutylene terephthalate (PBT) and polyethylene terephthalate (PET) belong to thermoplastic polyester materials, and the chemical structures of the two are highly similar, but the mechanical properties such as strength and toughness of the two as pure resins cannot meet the needs of complex engineering structural parts, and they are usually modified by blending, reinforcing, filling and other methods for engineering plastics. For example, glass fiber reinforced modified PBT composite material has good mechanical properties, fatigue resistance, wear resistance and dimensional stability, and is widely used in electronic appliances, automobiles, household appliances and other fields. However, the molecular chain segment movement ability of PBT resin is poor, and it is easy to crystallize, and the ends or edges of glass fibers in the composite material are stress concentration points, and the thermal expansion coefficients of PBT resin and glass fibers have large differences, so that the glass fiber reinforced PBT composite material is prone to brittle fracture under low temperature conditions. In the prior art, the low temperature toughness of the glass fiber reinforced PBT composite material is generally improved by adding a toughening agent, but the toughening agent usually reduces the rigidity or heat resistance of the material to some extent. SUMMARY

[0003] The present application aims to overcome the deficiencies of the prior art and provide a polyester composition and a preparation method and application thereof.

[0004] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows: In a first aspect, the present application provides a polyester composition, which comprises the following components in parts by weight: 50-90 parts of polyester resin, 0.2-3 parts of nano filler, and 5-40 parts of glass fiber; The polyester resin comprises polybutylene terephthalate (PBT) and / or polyethylene terephthalate (PET); The nano filler comprises nanoparticles and nanofibers; The sphericity of the nanoparticles is 0.9-1; The particle size D10, D50 and D90 of the nanoparticles satisfy (D90-D10) / D50≤1.3.

[0005] The present application is to combine specific nanoparticles with nanofibers to form a nanofiller, the approximately spherical nanoparticles in the polyester resin as a uniform distribution of stress concentration points, and when subjected to external force, a large number of small crazes and shear bands are induced to effectively absorb impact energy; while the nanofiber can use its fibrous structure to bridge microcracks, and synergistically with the interlaced crazes and shear bands to effectively prevent microcracks from developing into macrocracks; by regulating the particle size D10, D50 and D90 of the nanoparticles to meet (D90-D10) / D50≤1.3, the uniformity of the stress field can be enhanced to avoid uneven stress concentration caused by individual nanoparticles with too large or too small particle size, so that the toughening effect is maximized and stable; the nanoparticles and nanofibers can also interact with the molecular chains of the polyester resin to form a large number of physical crosslinking points between the molecular chains, and promote the formation of fine grain structure during the processing and cooling process, and release and disperse the internal stress inside the material, so that the polyester composition has good low-temperature toughness, heat resistance and low-temperature cracking resistance.

[0006] The polyester resin in the polyester composition is the base resin, and the mass fraction is greater than or equal to 48%.

[0007] In some embodiments, the weight fraction of the polyester resin in the polyester composition can be, but is not limited to, 50 parts, 52 parts, 54 parts, 56 parts, 58 parts, 60 parts, 62 parts, 64 parts, 66 parts, 68 parts, 70 parts, 72 parts, 74 parts, 76 parts, 78 parts, 80 parts, 82 parts, 84 parts, 86 parts, 88 parts, or 90 parts, or within the range formed by any two of the above values.

[0008] In some embodiments, the weight fraction of the nanofiller in the polyester composition can be, but is not limited to, 0.2 parts, 0.4 parts, 0.6 parts, 0.8 parts, 1 part, 1.2 parts, 1.4 parts, 1.6 parts, 1.8 parts, 2 parts, 2.2 parts, 2.4 parts, 2.6 parts, 2.8 parts, or 3 parts, or within the range formed by any two of the above values.

[0009] Based on the total mass of the polyester composition, the mass fraction of the nanofiller is 0.15% to 3.5%, which can be, but is not limited to, 0.15%, 0.2%, 0.25%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, or 3.5%, or within the range formed by any two of the above values.

[0010] In some embodiments, the amount of glass fiber in the polyester composition can be, but is not limited to, 5 parts, 6 parts, 8 parts, 10 parts, 12 parts, 14 parts, 16 parts, 18 parts, 20 parts, 22 parts, 24 parts, 26 parts, 28 parts, 30 parts, 32 parts, 34 parts, 36 parts, 38 parts, or 40 parts, or within a range between any two of the above values.

[0011] In some embodiments, the retained average length of the glass fiber in the polyester composition can be, but is not limited to, 100 μm, 120 μm, 140 μm, 160 μm, 180 μm, 200 μm, 220 μm, 240 μm, 260 μm, 280 μm, or 300 μm, or within a range between any two of the above values.

[0012] The retained average length of the glass fiber can be measured by first burning the polyester composition at a high temperature of 650 °C for 30 min to remove the resin matrix and retain the inorganic matter; then using ultrasonic treatment to screen the glass fiber, uniformly dispersing the glass fiber in water, and using a two-dimensional test to measure the retained average length of the glass fiber.

[0013] In some embodiments, the sphericity of the nanoparticles can be, but is not limited to, 0.9, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, or 1, or within a range between any two of the above values. The sphericity of the nanoparticles can be measured according to standard ISO 13322-2.

[0014] In some embodiments, the value of (D90-D10) / D50 can be, but is not limited to, 1.3, 1.2, 1.1, 1, 0.9, or 0.8, or within a range between any two of the above values. The particle sizes D10, D50, and D90 of the nanoparticles can be measured according to standard GB / T 19077-2016 “Particle size distribution - Laser diffraction method”.

[0015] As a preferred embodiment of the polyester composition of the present application, the mass ratio of the nanoparticles to the nanofibers is (0.3-10):1, which can be, but is not limited to, 0.3:1, 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, 5.5:1, 6:1, 6.5:1, 7:1, 7.5:1, 8:1, 8.5:1, 9:1, 9.5:1, or 10:1, or within a range between any two of the above values.

[0016] As a preferred embodiment of the polyester composition of the present application, the retained average particle size of the nanoparticles is 500 nm to 1500 nm, for example, but not limited to, 500 nm, 550 nm, 600 nm, 650 nm, 700 nm, 750 nm, 800 nm, 850 nm, 900 nm, 950 nm, 1000 nm, 1050 nm, 1100 nm, 1150 nm, 1200 nm, 1250 nm, 1300 nm, 1350 nm, 1400 nm, 1450 nm, or 1500 nm, or within a range between any two of the above values.

[0017] As a preferred embodiment of the polyester composition of the present application, the retained average length of the nanofiber is 10 μm to 500 μm, preferably 12 μm to 200 μm, for example, but not limited to, 10 μm, 15 μm, 20 μm, 40 μm, 60 μm, 80 μm, 100 μm, 120 μm, 140 μm, 150 μm, 160 μm, 180 μm, 200 μm, 220 μm, 240 μm, 260 μm, 280 μm, 300 μm, 320 μm, 340 μm, 360 μm, 380 μm, 400 μm, 420 μm, 440 μm, 460 μm, 480 μm, or 500 μm, or within a range between any two of the above values.

[0018] The retained average particle size of the nanoparticles or the retained average length of the nanofiber can be measured by the following test method: the polyester resin in the polyester composition is separated from the nanofiller by dissolution method, and then characterized by scanning electron microscope. Within the same selected range, 50 nanoparticles or nanofibers are randomly selected for measurement, and then the arithmetic average is calculated to obtain the retained average particle size of the nanoparticles or the retained average length of the nanofiber.

[0019] As a preferred embodiment of the polyester composition of the present application, the intrinsic viscosity of the polybutylene terephthalate is 0.6 dL / g to 1.5 dL / g, for example, but not limited to, 0.6 dL / g, 0.65 dL / g, 0.7 dL / g, 0.75 dL / g, 0.8 dL / g, 0.85 dL / g, 0.9 dL / g, 0.95 dL / g, 1 dL / g, 1.05 dL / g, 1.1 dL / g, 1.15 dL / g, 1.2 dL / g, 1.25 dL / g, 1.3 dL / g, 1.35 dL / g, 1.4 dL / g, 1.45 dL / g, or 1.5 dL / g, or within a range between any two of the above values.

[0020] As a preferred embodiment of the polyester composition of the present application, the intrinsic viscosity of the polyethylene terephthalate is 0.6 dL / g to 1.5 dL / g, which can be but is not limited to 0.6 dL / g, 0.65 dL / g, 0.7 dL / g, 0.75 dL / g, 0.8 dL / g, 0.85 dL / g, 0.9 dL / g, 0.95 dL / g, 1 dL / g, 1.05 dL / g, 1.1 dL / g, 1.15 dL / g, 1.2 dL / g, 1.25 dL / g, 1.3 dL / g, 1.35 dL / g, 1.4 dL / g, 1.45 dL / g, or 1.5 dL / g, or within a range between any two of the above values.

[0021] The intrinsic viscosity of the polybutylene terephthalate and the polyethylene terephthalate is determined according to the standard GB / T14190-2017; specifically, the test is performed using an Ubbelohde viscometer in a constant temperature water bath, and a mixed solvent of phenol and tetrachloroethane is selected as the solvent, with a mass ratio of phenol:tetrachloroethane = 3:2, and a test temperature of 25°C.

[0022] As a preferred embodiment of the polyester composition of the present application, the nanoparticles include at least one of nano-silicon dioxide, nano-aluminum oxide, nano-calcium carbonate, nano-montmorillonite, and nano-hydrotalcite; the nanoparticles meeting the requirements of the present application can be obtained by self-preparation or purchased from the market. The self-preparation method includes screening commercially available products, or preparing by a sol-gel method or a sol-gel method combined with a supercritical fluid technology.

[0023] Preferably, the nanoparticles are nano-silicon dioxide.

[0024] As a preferred embodiment of the polyester composition of the present application, the nanofibers include at least one of carbon nanotubes, silicon nanotubes, and titanium dioxide nanotubes.

[0025] As a preferred embodiment of the polyester composition of the present application, the functional auxiliary in the components of the polyester composition further includes 0.1 to 10 parts by weight of at least one of a flame retardant, an antioxidant, and a lubricant.

[0026] In some embodiments, the parts by weight of the functional auxiliary in the polyester composition can be but are not limited to 0.1 part, 0.2 part, 0.4 part, 0.8 part, 1 part, 1.5 part, 2 part, 2.5 part, 3 part, 3.5 part, 4 part, 4.5 part, 5 part, 5.5 part, 6 part, 6.5 part, 7 part, 7.5 part, 8 part, 8.5 part, 9 part, 9.5 part, or 10 part, or within a range between any two of the above values.

[0027] In some embodiments, the flame retardant includes, but is not limited to, at least one of tetrabromobisphenol A, brominated triazine, brominated epoxy, decabromodiphenyl ethane, decabromodiphenyl ether, brominated polyimide, brominated polystyrene, polybrominated styrene, brominated polycarbonate, brominated polyacrylate, antimony trioxide, sodium antimonate, antimony pentoxide, aluminum hypophosphite, diethylaluminum hypophosphite, diisobutylaluminum hypophosphite, melamine polyphosphate, and melamine cyanurate.

[0028] In some embodiments, the antioxidant includes, but is not limited to, at least one of hindered phenolic antioxidants, phosphite antioxidants, and organosulfur antioxidants.

[0029] In some embodiments, the lubricant includes, but is not limited to, at least one of aliphatic carboxylic acid esters, erucamide, ethylene bis-stearamide, montan esters, polyethylene wax, and oxidized polyethylene wax.

[0030] Secondly, the present invention provides a method for preparing the above-mentioned polyester composition, comprising the following steps: mixing the components evenly and then melt-extruding to obtain the polyester composition.

[0031] For example, a twin-screw extruder can be used for melt extrusion. The feed rate of the twin-screw extruder is 100 kg / h to 800 kg / h. The screw temperatures of each section of the twin-screw extruder from the feed port to the die head are 220°C to 230°C, 230°C to 240°C, 230°C to 240°C, 240°C to 250°C, 250°C to 260°C, 240°C to 250°C, 240°C to 250°C, 230°C to 240°C, and 230°C to 240°C, respectively. The screw speed is 250 rpm to 600 rpm. Preferably, the glass fiber is added to the twin-screw extruder via side feeding.

[0032] Thirdly, the present invention provides an application of the above-mentioned polyester composition in the preparation of automotive parts, electronic appliances or household appliances.

[0033] For example, automotive parts include, but are not limited to, fuse boxes, ignition coils, engine peripheral components, fuel systems, etc.; electronic and electrical appliances include, but are not limited to, connectors, switches, relay housings, sockets, coil frames, etc.; household appliances include, but are not limited to, the housings and internal parts of electric irons, hair dryers, rice cookers, etc.

[0034] Fourthly, the present invention provides an automotive component made of the aforementioned polyester composition.

[0035] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention combines specific nanoparticles and nanofibers to form a nanofiller. The nearly spherical nanoparticles act as uniformly distributed stress concentration points in the polyester resin, inducing numerous and minute crazes and shear bands to effectively absorb impact energy when subjected to external forces. The nanofibers, with their fibrous structure, can bridge microcracks and work synergistically with the intersecting crazes and shear bands to effectively prevent microcracks from developing into macrocracks. By controlling the particle sizes D10, D50, and D90 of the nanoparticles to satisfy (D90-D10) / D50≤1.3, the uniformity of the stress field can be enhanced, avoiding uneven stress concentration caused by individual nanoparticles being too large or too small, thus maximizing and stabilizing the toughening effect. The nanoparticles and nanofibers can also interact with the molecular chains of the polyester resin, forming numerous physical crosslinking points between the molecular chains. Simultaneously, during processing and cooling, they promote the formation of fine crystalline structures and release and disperse the internal stress of the material, thereby giving the polyester composition excellent low-temperature toughness, heat resistance, and low-temperature crack resistance. Detailed Implementation

[0036] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0037] Unless otherwise specified, all other materials, reagents, etc. used in the examples and comparative examples are commercially available.

[0038] 1. Raw materials and reagents 1) Polyester resin PBT resin 1, intrinsic viscosity 1.0 dL / g, grade PBT GX121, manufacturer: Sinopec Yizheng Chemical Fiber Co., Ltd. PBT resin 2, intrinsic viscosity 0.8 dL / g, grade PBT GX112, manufacturer: Sinopec Yizheng Chemical Fiber Co., Ltd. PET resin, intrinsic viscosity 0.8 dL / g, grade PET BG80, manufacturer: Sinopec Yizheng Chemical Fiber Co., Ltd.

[0039] 2) Nanoparticles Nano-silica 1, self-made, with sphericity of 0.93, D50=1400nm, D90 / D10=2.1, (D90-D10) / D50=0.92; Nano-silica 2, self-made, with sphericity of 0.96, D50=1000nm, D90 / D10=1.75, (D90-D10) / D50=0.93; Nano silica 3, purchased from Xianfeng Nano, has a sphericity of 0.85, D50=1000nm, D90 / D10=4.0, and (D90-D10) / D50=0.5; Nano-silica 1 and nano-silica 2 were prepared by a sol-gel method combined with supercritical fluid technology, specifically including the following steps: Step 1: Precursor hydrolysis and condensation Tetraethyl orthosilicate (TEOS) was used as the silicon source. It was mixed with anhydrous ethanol (solvent), deionized water (hydrolysis agent) and a trace amount of ammonia (catalyst), and then subjected to hydrolysis-condensation reaction at 60±5°C for 2~6h to obtain silica wet gel blocks. The particle size of nano silica was adjusted by controlling the concentration of ammonia and the hydrolysis-condensation reaction time. Step 2: Solvent replacement The silica wet gel block was immersed in acetone for ≥24 hours, and the acetone was replaced with fresh acetone every 12 hours to obtain the replacement gel. Step 3: Supercritical fluid drying S1. Loading and CO2 injection: Place the displaced gel into a high-pressure drying vessel, seal it, and inject low-temperature liquid carbon dioxide until the sample is submerged. S2. Increase temperature and pressure to supercritical state: Start the equipment and slowly increase the temperature and pressure of the system to 50°C and 10MPa, respectively. S3. Dynamic extraction of pore solvent: Under the condition of maintaining supercritical state, supercritical CO2 fluid is introduced from the bottom of the vessel at a flow rate of 50 kg / 10 min, while fresh liquid CO2 is continuously pumped in from the top of the vessel for replenishment, and the extraction and drying process lasts for 5 to 20 hours. S4. Constant temperature and slow pressure reduction: After the solvent is completely extracted, reduce the system pressure to atmospheric pressure at a rate of 0.1 MPa / min, open the vessel and take out the sample to obtain nano-silica.

[0040] 3) Nanofibers Carbon nanotube 1, with an average length of 150 μm and an average diameter of 12 nm, grade FT6807, manufactured by Jiangsu Tiannai Technology Co., Ltd. Carbon nanotube 2, with an average length of 15μm and an average diameter of 10nm, grade FT9107NP, manufactured by Jiangsu Tiannai Technology Co., Ltd.

[0041] 4) Glass fiber Glass fiber 1, diameter 11μm, grade ECS11-4.5-534A, manufacturer: China Jushi; Glass fiber 2, diameter 13μm, grade ECS13-4.5-534A, manufacturer: China Jushi.

[0042] 5) Functional additives The antioxidant is a compound of antioxidant 1010 (commercially available) and antioxidant 168 (commercially available) in a mass ratio of 1:1.

[0043] 2. Preparation method of the polyester composition of the present invention According to the formula, the components are mixed evenly and then added to a twin-screw extruder for melt extrusion and granulation to obtain a polyester composition. The glass fiber is fed into the twin-screw extruder via a side-feed method. The screw temperatures of each section of the twin-screw extruder from the feed port to the die head are 220℃, 230℃, 230℃, 240℃, 250℃, 240℃, 240℃, 230℃, and 230℃, respectively, and the screw speed is 350 rpm.

[0044] Table 1 shows the weight parts of each component in the polyester compositions of Examples 1 to 6. Table 2 shows the weight parts of each component in the polyester compositions of Examples 7 to 11. Table 3 shows the weight parts of each component in the polyester compositions of Comparative Examples 1 to 5. The " / " in Tables 1, 2 and 3 indicates that there are no relevant parameters.

[0045] 3. Performance Testing 1) Low-temperature notched impact strength test: After each product is injection molded into a test impact specimen with dimensions of (80±2)×(10.0±0.2)×(4.0±0.2)mm and a notch width of (8.0±0.2)mm, it is first placed in a freezer at -40°C for 8 hours. Then, it is taken out and notched impact strength test is performed according to GB / T1843-2008. The notch is type A, the impact energy is 5.5J, and the test is completed within 20 seconds after being taken out.

[0046] 2) Heat resistance test: Each product is injection molded into a 125×13.0×1.0mm sample. A 10g weight is added to the middle of the sample, and it is placed in an oven with a span of 6cm and a temperature of 85°C for 40 minutes. After cooling, the height from the top of the sample to the horizontal plane is measured as the deformation degree, in mm. The lower the deformation degree, the better the heat resistance.

[0047] 3) Low-temperature crack resistance: Each product was made into a sheet sample with a thickness of 3mm and frozen at -30℃ for 8h; then a steel ball weighing 0.5kg was placed at a certain height and allowed to fall freely to impact the frozen sheet sample. The low-temperature crack resistance was evaluated by the height at which the sheet sample just broke through the ball.

[0048] Table 4. Performance of the polyester compositions in each example and comparative example. According to the data in Table 4, the low-temperature notched impact strength of the polyester compositions in Examples 1 to 11 all reached 6.5 kJ / m. 2 The above results show that the deformation is less than or equal to 11.5 mm and the drop height is greater than or equal to 0.70 m, indicating that the polyester composition of the present invention possesses good low-temperature toughness, heat resistance, and low-temperature crack resistance. Meanwhile, as can be seen from Example 1 and Comparative Example 1, when the sphericity of the nanoparticles is small and the (D90-D10) / D50 ratio is too large, it not only reduces the low-temperature notched impact strength of the polyester composition but also deteriorates its heat resistance and low-temperature crack resistance. Furthermore, as can be seen from Example 1 and Comparative Examples 2 to 3, using nanoparticles or nanofibers alone as nanofillers is insufficient to effectively improve the low-temperature toughness, heat resistance, and low-temperature crack resistance of the polyester composition. As can be seen from Example 10 and Comparative Example 4, excessive addition of nanofillers significantly reduces the low-temperature crack resistance of the polyester composition. As can be seen from Example 11 and Comparative Example 5, insufficient addition of nanofillers deteriorates the low-temperature toughness and heat resistance of the polyester composition.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A polyester composition, characterized in that, By weight, it includes the following components: Polyester resin 50-90 parts, nano filler 0.2-3 parts, glass fiber 5-40 parts; The polyester resin includes polybutylene terephthalate and / or polyethylene terephthalate; The nanofiller includes nanoparticles and nanofibers; The sphericity of the nanoparticles is 0.9~1; The particle sizes D10, D50, and D90 of the nanoparticles satisfy the following condition: (D90-D10) / D50≤1.

3.

2. The polyester composition according to claim 1, characterized in that, The mass ratio of the nanoparticles to the nanofibers is (0.3~10):

1.

3. The polyester composition according to claim 1, characterized in that, The average retained particle size of the nanoparticles is 500 nm to 1500 nm.

4. The polyester composition according to claim 1, characterized in that, The average length of the retained nanofibers ranges from 10 μm to 500 μm.

5. The polyester composition according to claim 1, characterized in that, The intrinsic viscosity of the polybutylene terephthalate is from 0.6 dL / g to 1.5 dL / g; And / or, the intrinsic viscosity of the polyethylene terephthalate is from 0.6 dL / g to 1.5 dL / g.

6. The polyester composition according to claim 1, characterized in that, The nanoparticles include at least one of nano-silica, nano-alumina, nano-calcium carbonate, nano-montmorillonite, and nano-hydrotalcite. And / or, the nanofibers include at least one of carbon nanotubes, silicon nanotubes, and titanium dioxide nanotubes.

7. The polyester composition according to claim 1, characterized in that, The polyester composition further includes 0.1 to 10 parts by weight of functional additives, which include at least one of flame retardants, antioxidants, and lubricants.

8. A method for preparing the polyester composition according to any one of claims 1 to 7, characterized in that, The process includes the following steps: mixing the components evenly and then melting and extruding them to obtain a polyester composition.

9. The use of the polyester composition according to any one of claims 1 to 7 in the manufacture of automobiles, electronic appliances or household appliances.

10. An automotive component, characterized in that, Made from the polyester composition according to any one of claims 1 to 7.

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