Polyester composite material capable of replacing transparent ABS material, preparation method and application thereof

Abstract

The application relates to a polyester composite material which can replace transparent ABS material, and a preparation method and application thereof, and belongs to the technical field of transparent polyester composite materials. The polyester composite material comprises modified PET resin 65-85 parts, PC resin 15-35 parts, ester exchange inhibitor 0.1-1 part, chain extender 0.2-2 parts, antioxidant 0.5-2 parts and lubricant 0.1-1 part; the modified PET resin is obtained after a sulfur-containing diol monomer is modified to PET resin. The difference between the refractive indexes of the modified PET resin and the PC resin is within 0.01. The composite material prepared by the application has mechanical properties which are equivalent to those of transparent ABS material, and some indexes are obviously better, and the light transmittance is equivalent to that of transparent ABS material.

Description

Technical Field

[0001] This invention belongs to the field of transparent polyester composite material technology, specifically relating to a polyester composite material that can replace transparent ABS material, its preparation method, and its application. Background Technology

[0002] Transparent ABS, an important branch of ordinary ABS resin, possesses excellent light transmittance while maintaining good mechanical and processing properties. It is widely used in electronic device housings, monitoring equipment windows, control panels, transparent sheets, and vacuum cleaner components, with continuously growing market demand. However, domestic production of transparent ABS resin has not yet achieved industrialization, relying entirely on imports, resulting in persistently high prices and significantly hindering the development of downstream industries. Against this backdrop, developing a high-performance, cost-effective alternative material with comparable light transmittance, mechanical properties, and processing properties to transparent ABS resin, while also having controllable production costs, readily available raw materials, and the potential for domestic mass production, has become an urgent need and research hotspot in the field of polymer materials and related downstream industries.

[0003] Polyethylene terephthalate (PET) is a preferred substrate for replacing transparent ABS resin due to its wide availability of raw materials, balanced mechanical properties, excellent chemical resistance, good recyclability, and high degree of domestic production. However, the structural characteristics of PET itself make it difficult to match the comprehensive performance of transparent ABS in its direct application. These technical bottlenecks are key factors restricting the industrialization of PET as a substitute for transparent ABS.

[0004] The primary challenge is controlling the balance between light transmittance and crystallization behavior. PET is a semi-crystalline polymer, with a crystallinity of 20%-30% under normal conditions. The crystalline regions produce strong light scattering, resulting in pure PET generally having a light transmittance below 70% and a haze above 15%, far below the light transmittance (≥85%) and low haze (≤2%) requirements of transparent ABS. If crystallization is suppressed to improve light transmittance through rapid cooling, the material may not crystallize completely, leading to secondary crystallization during subsequent use, causing dimensional deformation, decreased light transmittance, and reduced mechanical stability. Therefore, achieving low crystallinity and high light transmittance while ensuring uniform crystalline morphology and excellent dimensional stability is the primary technical difficulty. Secondly, improving impact resistance is another challenge. Transparent ABS, containing a butadiene rubber phase, possesses excellent toughness and impact resistance, with a cantilever beam notched impact strength typically reaching 9-15 kJ / m². In contrast, pure PET exhibits poor impact toughness at room temperature, with a notched impact strength of only 3-6 kJ / m², making it prone to brittle fracture and unable to meet the impact protection requirements of applications such as electronic casings and surveillance windows. Traditional toughening modifications often involve introducing elastomers, but elastomers have poor compatibility with PET substrates, easily leading to phase separation. This not only reduces the material's light transmittance but may also cause a decline in mechanical properties such as tensile strength and rigidity, making it difficult to simultaneously achieve the synergistic requirements of "high light transmittance + high impact resistance + balanced mechanical properties." Improving impact toughness without sacrificing light transmittance and rigidity is one of the core technological challenges.

[0005] Patent application CN 111393823A discloses a method to improve the interfacial bonding of PET / PC blends by adding POE-g-MAH (polyolefin elastomer grafted with maleic anhydride) as a compatibilizer, thereby obtaining alloy materials with excellent comprehensive performance. However, the PET / PC alloy obtained by this technology is opaque and cannot be used to replace transparent ABS materials. Patent application CN117820824A discloses a modified PET composite material, its preparation method, and its application, mainly by modifying PET with PC and adding toughening agents, compatibilizers, nucleating agents, and light diffusing agents. The disadvantage of this technology is that the addition of the above-mentioned additives reduces its light transmittance and significantly affects haze. Summary of the Invention

[0006] To address the shortcomings of existing technologies and the difficulty in matching the properties of transparent ABS when using PET as a substitute, this invention aims to design a polyester composite material. By introducing sulfur-containing diol monomers into polyethylene terephthalate (PET) resin, the refractive index of the modified PET is optimized, achieving a high degree of matching with that of PC resin, while effectively reducing the crystallization tendency of PET resin. Based on this, by controlling the proportion of polycarbonate (PC) resin added, and supplemented with ester exchange inhibitors, chain extenders, stabilizers, antioxidants, and lubricants, the mixture is uniformly mixed in a high-speed mixer and then melt-blended and granulated using a twin-screw extruder to prepare a high-performance composite material with high transparency, excellent heat resistance, and good impact resistance. Through molecular structure design, precise component matching, and synergistic regulation of additives, the invention ultimately achieves a light transmittance comparable to transparent ABS, mechanical properties comparable to or better, lower cost, and the ability for domestic mass production. This composite material shows application potential as a substitute for traditional transparent ABS materials in fields such as electronic device housings, transparent windows, monitoring panels, and transparent sheets, and is expected to provide superior solutions for related industries.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] On one hand, the present invention provides a polyester composite material comprising the following parts by weight of raw materials:

[0009] The mixture consists of 65-85 parts modified PET resin, 15-35 parts PC resin, 0.1-1 part transesterification inhibitor, 0.2-2 parts chain extender, 0.5-2 parts antioxidant, and 0.1-1 part lubricant. Modified PET is the main base material, ensuring low cost, easy processing, and recyclability. PC is used to improve impact resistance, heat resistance, and optical properties. A modified PET ratio of less than 65 parts may result in an excessive PC content, increasing costs, making processing more difficult, and reducing dimensional stability. A modified PET ratio of more than 85 parts may result in insufficient PC content, preventing the impact strength and heat resistance from reaching the level of transparent ABS. Only within this ratio range can transparency, mechanical properties, cost, and processability be balanced.

[0010] The modified PET resin is obtained by modifying PET resin with a sulfur-containing diol monomer; the monomer contains both sulfur atoms and aromatic rings in a dual structure. Sulfur atoms can significantly improve the refractive index, enabling optical matching between PET and PC; aromatic rings ensure chain segment rigidity and heat resistance, and improve structural compatibility with PC; the dual structure together disrupts the regularity of the PET chain, inhibiting crystallization, reducing haze, and improving light transmittance; the absence of sulfur would lead to a mismatch in refractive index and poor transparency; the absence of aromatic rings would lead to poor compatibility and low impact resistance; only by simultaneously containing sulfur and aromatic rings can a synergistic effect of high transparency and high impact resistance be achieved.

[0011] The refractive index difference between the modified PET resin and the PC resin is within 0.01. If the refractive index difference is greater than 0.01, it will cause strong light scattering at the interface between the two phases, resulting in a sharp drop in transmittance, a surge in haze, and opacity of the material. Only when the difference is ≤0.01 can optical homogeneity, high transmittance, and low haze be achieved, reaching the level of transparent ABS.

[0012] The polyester composite material described herein has a modified PET resin with a refractive index of 1.58~1.585 and a PC resin with a refractive index of 1.58~1.59. This invention improves the refractive index of PET by introducing aromatic rings and sulfur atoms into the PET molecular chain, making the refractive indices of the modified PET and PC very close or even identical. An intrinsic viscosity >0.8 enhances the mechanical properties of the modified PET, avoiding any impact on the performance of the polyester composite material prepared after blending with PC. Sulfur monomers, as the third monomer besides EG, decrease the regularity of the PET resin chain when introduced into it, thereby weakening its crystallization ability and reducing its crystallization tendency.

[0013] In the aforementioned polyester composite material, the sulfur-containing diol monomer is a sulfur-containing bisphenol derivative;

[0014] The intrinsic viscosity of the modified PET resin is 0.8~0.85 dL / g. It is prepared using a two-step method: polymerization followed by vacuum thickening in a rotary drum. If the intrinsic viscosity is too low, the molecular weight is insufficient, resulting in low mechanical strength, poor impact resistance, and easy breakage; if the intrinsic viscosity is too high, the melt viscosity is too large, making it difficult to process and causing unstable extrusion. The preferred intrinsic viscosity range is 0.8~0.85 dL / g, ensuring both mechanical strength and good processability.

[0015] The PC resin is bisphenol A type polycarbonate with a density of 1.18~1.22 g / cm³. 3 The melt index is 5~25 g / 10min.

[0016] The transesterification inhibitor is selected from at least one of triphenyl phosphate, triphenyl phosphite, sodium dihydrogen phosphate, sodium hexametaphosphate, or disodium dihydrogen pyrophosphate. Both PC resin and modified PET resin molecular chains contain ester bonds. The role of the transesterification agent is to reduce transesterification between PC resin and modified PET resin, preventing excessive transesterification during blending and modification that could lead to loss of mechanical properties. A certain degree of transesterification is beneficial for improving the compatibility between PC resin and modified PET resin. Both PET and PC contain ester bonds, and excessive transesterification easily occurs during high-temperature blending, leading to molecular chain breakage, degradation, and a sharp drop in performance. Without an inhibitor, impact, strength, and transparency all deteriorate. Only by adding an appropriate amount of inhibitor to moderately suppress transesterification can the molecular structure be protected and the overall performance stabilized.

[0017] The chain extender is at least one of ADR4400, ADR4468, or chain extender 6059; high-temperature processing can cause polymer chain breakage, resulting in a decrease in molecular weight and a deterioration in toughness; without the addition of a chain extender, the notched impact strength is easily reduced significantly, failing to reach the impact resistance level of ABS; the chain extender can repair the molecular chain, increase the molecular weight, and significantly improve toughness without sacrificing transparency.

[0018] The antioxidant is at least one of antioxidant 1010, antioxidant 1076, antioxidant 1315 or antioxidant 264;

[0019] The lubricant is at least one of pentaerythritol stearate (PETS), octadecyl stearate, or glyceryl monostearate. Without antioxidants, the material yellows, decomposes, and its performance deteriorates; without lubricants, processing becomes difficult, the surface is poor, and transparency is affected.

[0020] The two work together to ensure stable processing, good appearance, and stable long-term performance.

[0021] The polyester composite material wherein the sulfur-containing diol monomer is selected from... , , or At least one of them.

[0022] The method for preparing the modified PET resin in the aforementioned polyester composite material includes:

[0023] Weigh terephthalic acid, ethylene glycol, sulfur-containing glycol monomer and polycondensation catalyst, and carry out esterification reaction under an inert gas atmosphere. After the esterification reaction is completed when the esterification conversion rate reaches 90% or above, carry out prepolymerization reaction, and then carry out polymerization reaction. When the stirring torque or stirring power reaches the expected value, discharge the material to obtain PET modified resin with intrinsic viscosity of 0.8~0.85 dL / g.

[0024] The polyester composite material wherein the molar ratio of terephthalic acid, ethylene glycol, and sulfur-containing diol monomers is 1:0.8~1.2:0.1~0.4; (the amount of sulfur-containing diol monomers added accounts for 10%-40% of the total alcohol molar ratio.)

[0025] The polycondensation catalyst is at least one of antimony-based, titanium-based, aluminum-based, or germanium-based catalysts; the amount of the polycondensation catalyst added is 100-500 ppm of the mass of terephthalic acid.

[0026] The conditions for the esterification reaction of the polyester composite material are: pressure 0.1-0.4 MPa, stirring speed 50-120 r / min, and temperature 225-255℃.

[0027] The conditions for the prepolymerization reaction are: reaction pressure 0.5~1 kPa, reaction temperature 240~265℃, and reaction time 40~60 min;

[0028] The polymerization reaction conditions are as follows: reaction pressure 10~300 Pa, reaction temperature 260~285℃, reaction time 90~180 min, and after the stirring torque or stirring power reaches the expected value, the PET modified resin with an intrinsic viscosity of 0.8~0.85 dL / g is obtained by discharging.

[0029] Secondly, the present invention provides a method for preparing the aforementioned polyester composite material, comprising the following steps:

[0030] Weigh out dried modified PET resin and PC resin, ester exchange inhibitor, chain extender, lubricant and antioxidant, mix them evenly to obtain a mixture, melt blend and extrude to obtain polyester composite material.

[0031] The preparation method described herein uses a twin-screw extruder for melt blending, wherein the screw temperature in the feeding section is 240-250℃, the screw temperature in the melting section is 250-260℃, and the screw temperature in the homogenization section is 260-268℃.

[0032] Thirdly, the polyester composite material is used in the fields of electronic device housings, transparent windows, monitoring panels, or transparent sheets.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1. Introducing sulfur-containing monomer diols into modified PET resin can significantly improve its refractive index, thereby effectively reducing the difference in refractive index with PC resin and improving transparency; at the same time, it reduces its crystallinity and even achieves an amorphous structure. In addition, the introduction of sulfur-containing monomer diols makes the PET chain structure closer to PC, thereby enhancing the compatibility of the two-phase interface through molecular-level structural matching without relying on olefin compatibilizers.

[0035] 2. This invention increases the compatibility of PET and PC by adding appropriate amounts of transesterification inhibitors and chain extenders, thereby causing a small amount of transesterification and chain extension reactions between PET and PC, without affecting the mechanical properties and transparency of the composite material.

[0036] 3. The raw materials PET and PC used in this invention are cheaper than transparent ABS materials, thus significantly reducing costs.

[0037] 4. The composite material prepared by this invention has mechanical properties comparable to those of transparent ABS material, and some indicators are even significantly better. Its light transmittance is comparable to that of transparent ABS material. Attached Figure Description

[0038] Figure 1 The DSC test results of the modified PET resin obtained in Example 1. Detailed Implementation

[0039] The present invention will be further illustrated by the following examples.

[0040] Example 1:

[0041] A method for preparing a polyester composite material that can replace transparent ABS includes:

[0042] (1) Add terephthalic acid, ethylene glycol, sulfur-containing glycol monomer and antimony acetate catalyst to the reaction vessel, replace the air in the polymerization vessel with inert gas, control the pressure in the polymerization vessel at 0.2 MPa, the speed of the stirrer at 80 r / min, control the temperature in the polymerization vessel at 240℃, calculate the esterification efficiency by the liquid discharge rate, and the esterification reaction ends when the conversion rate reaches 94%.

[0043] The sulfur-containing diol monomer is shown in Formula I: (Formula I).

[0044] (2) Vacuum the reactor, control the reactor pressure at 0.7 kPa, control the polymerization temperature at 250°C, and react for 50 min; then control the reactor pressure at 100 Pa, control the polymerization temperature at 270°C, and react for 120 min; when the stirring current / stirring power reaches the expected value, the modified PET resin with an intrinsic viscosity of about 0.82 dL / g and a refractive index of 1.582 is obtained by discharging.

[0045] (3) Weigh the modified PET resin and bisphenol A polycarbonate with a refractive index of 1.584 prepared above, and dry them at 120°C for 5 hours.

[0046] (4) Weigh 70 parts by weight of the dried modified PET resin, 20 parts by weight of bisphenol A polycarbonate with a refractive index of 1.584, 0.5 parts by weight of triphenyl phosphate, 1 part by weight of ADR4400, 1 part by weight of antioxidant 1010, and 0.5 parts by weight of pentaerythritol stearate. Add them to a high-speed mixer and mix evenly to obtain a mixture.

[0047] (5) The prepared mixture is added to a twin-screw extruder for extrusion granulation to obtain a polyester composite material; wherein the screw temperature in the feeding section is 245℃, the screw temperature in the melting section is 255℃, and the screw temperature in the homogenization section is 266℃.

[0048] Example 2:

[0049] A method for preparing a polyester composite material that can replace transparent ABS includes:

[0050] (1) Add terephthalic acid, ethylene glycol, sulfur-containing diol monomer and tetrabutyl titanate to the reaction vessel, replace the air in the polymerization vessel with inert gas, control the pressure in the polymerization vessel at 0.1 MPa, the speed of the stirrer at 50 r / min, control the temperature in the polymerization vessel at 225℃, calculate the esterification efficiency by the liquid discharge rate, and the esterification reaction ends when the conversion rate reaches 90%.

[0051] The sulfur-containing diol monomer is shown in Formula II: (Formula II).

[0052] (2) Vacuum the reactor, control the reactor pressure at 0.5 kPa, control the temperature inside the polymerization reactor at 240°C, and react for 40 min; then control the reactor pressure at 10 Pa, control the temperature inside the polymerization reactor at 260°C, and react for 90 min; when the stirring current / stirring power reaches the expected value, the product with an intrinsic viscosity of about 0.6 dL / g is obtained by discharging the stage PET resin product.

[0053] (3) The modified PET resin with an intrinsic viscosity of 0.6 dL / g was put into the drum. Under vacuum, the temperature inside the drum was raised to 200°C after 8 hours and kept at that temperature for 10 hours to obtain a modified PET resin with an intrinsic viscosity of 0.83 dL / g and a refractive index of 1.583.

[0054] (4) Weigh the modified PET resin and bisphenol A polycarbonate with a refractive index of 1.584 prepared above, and dry them at 120°C for 4 hours.

[0055] (5) Weigh 65 parts by weight of dried modified PET resin, 35 parts by weight of bisphenol A polycarbonate, 0.1 parts by weight of sodium dihydrogen phosphate, 0.2 parts by weight of ADR4468, 2 parts by weight of antioxidant 1315, and 0.1 parts by weight of stearic acid octadecyl ester, add them to a high-speed mixer and mix evenly to obtain a mixture.

[0056] (6) The prepared mixture is added to a twin-screw extruder for extrusion granulation to obtain a polyester composite material; wherein the screw temperature in the feeding section is 240℃, the screw temperature in the melting section is 250℃, and the screw temperature in the homogenization section is 260℃.

[0057] Example 3:

[0058] A method for preparing a polyester composite material that can replace transparent ABS includes:

[0059] (1) Add terephthalic acid, ethylene glycol, sulfur-containing diol monomer and germanium dioxide to the reaction vessel, replace the air in the polymerization vessel with inert gas, control the pressure in the polymerization vessel at 0.4 MPa, the speed of the stirrer at 120 r / min, control the temperature in the polymerization vessel at 255℃, calculate the esterification efficiency by the liquid discharge rate, and the esterification reaction ends when the conversion rate reaches 95%.

[0060] The sulfur-containing diol monomer is shown in Formula III: (Formula III).

[0061] (2) Vacuum the reactor, control the reactor pressure at 1 kPa, control the temperature inside the polymerization reactor at 265°C, and react for 60 min; then control the reactor pressure at 300 Pa, control the temperature inside the polymerization reactor at 285°C, and react for 180 min; when the stirring current / stirring power reaches the expected value, the product with an intrinsic viscosity of about 0.65 dL / g is obtained by discharging the stage PET resin product.

[0062] (3) The modified PET resin with an intrinsic viscosity of 0.65 dL / g was put into the drum. Under vacuum, the temperature inside the drum was raised to 225°C after 8 hours and kept at this temperature for 30 hours to obtain a modified PET resin with an intrinsic viscosity of 0.85 dL / g and a refractive index of 1.584.

[0063] (4) Weigh the modified PET resin and bisphenol A polycarbonate with a refractive index of 1.584 prepared above, and dry them at 120°C for 6 hours.

[0064] (5) Weigh 85 parts by weight of the dried modified PET resin, 15 parts by weight of bisphenol A polycarbonate, 1 part by weight of sodium hexametaphosphate, 2 parts by weight of chain extender 6059, 0.5 parts by weight of antioxidant 264, and 1 part by weight of glyceryl monostearate. Add them to a high-speed mixer and mix evenly to obtain a mixture.

[0065] (6) The prepared mixture is added to a twin-screw extruder for extrusion granulation to obtain a polyester composite material; wherein the screw temperature in the feeding section is 250℃, the screw temperature in the melting section is 260℃, and the screw temperature in the homogenization section is 268℃.

[0066] Example 4:

[0067] A method for preparing a polyester composite material that can replace transparent ABS includes:

[0068] (1) Add terephthalic acid, ethylene glycol, sulfur-containing glycol monomer and aluminum acetate catalyst to the reactor, replace the air in the polymerization reactor with inert gas, control the pressure in the polymerization reactor at 0.3 MPa, the speed of the stirrer at 70 r / min, control the temperature in the polymerization reactor at 245℃, calculate the esterification efficiency by the liquid discharge rate, and the esterification reaction ends when the conversion rate reaches 90%.

[0069] The sulfur-containing diol monomer is shown in Formula IV: (Formula IV).

[0070] (2) Vacuum the reactor, control the reactor pressure at 0.7 kPa, control the temperature inside the polymerization reactor at 250°C, and react for 50 min; then control the reactor pressure at 100 Pa, control the temperature inside the polymerization reactor at 270°C, and react for 120 min; when the stirring current / stirring power reaches the expected value, the product with an intrinsic viscosity of about 0.68 dL / g is obtained by discharging the product.

[0071] (3) The modified PET resin with an intrinsic viscosity of 0.68 dL / g was put into the drum. Under vacuum, the temperature inside the drum was raised to 220°C after 8 hours and kept at this temperature for 20 hours to obtain a modified PET resin with an intrinsic viscosity of 0.82 dL / g and a refractive index of 1.58.

[0072] (4) Weigh the modified PET resin and bisphenol A polycarbonate with a refractive index of 1.584 prepared above, and dry them at 120°C for 5 hours.

[0073] (5) Weigh 70 parts by weight of dried modified PET resin, 20 parts by weight of bisphenol A polycarbonate, 0.5 parts by weight of disodium dihydrogen pyrophosphate, 1 part by weight of ADR4400, 1 part by weight of antioxidant 1010, and 0.5 parts by weight of pentaerythritol stearate. Add them to a high-speed mixer and mix evenly to obtain a mixture.

[0074] (6) The prepared mixture is added to a twin-screw extruder for extrusion granulation to obtain a polyester composite material; wherein the screw temperature in the feeding section is 245℃, the screw temperature in the melting section is 255℃, and the screw temperature in the homogenization section is 266℃.

[0075] Comparative Example 1:

[0076] A method for preparing a PET-PC polyester composite material:

[0077] Weigh out 70 parts by weight of dried PET resin with a refractive index of 1.575, 20 parts by weight of bisphenol A polycarbonate with a refractive index of 1.584, 0.5 parts by weight of triphenyl phosphate, 1 part by weight of ADR4400, 1 part by weight of antioxidant 1010, and 0.5 parts by weight of pentaerythritol stearate. Add them to a high-speed mixer and mix evenly to obtain a mixture.

[0078] The prepared mixture was added to a twin-screw extruder for extrusion granulation to obtain a polyester composite material; wherein the screw temperature in the feeding section was 245℃, the screw temperature in the melting section was 255℃, and the screw temperature in the homogenization section was 266℃.

[0079] Comparative Example 2:

[0080] The purchased existing product ABS-920 was used as comparative example 2.

[0081] Comparative Example 3:

[0082] The purchased existing PET resin with a refractive index of 1.575 was used as Comparative Example 3.

[0083] Comparative Example 4:

[0084] The steps were the same as in Example 1, except that the material was discharged at a lower stirring current (25 Hz / 60 W) to obtain a modified PET resin with an intrinsic viscosity of 0.61 dL / g and a refractive index of 1.582 in step (2). The other steps were the same, and the composite material was finally prepared.

[0085] Comparative Example 5:

[0086] The steps are the same as in Example 1, except that the disulfide monomer is replaced with 2,2'-thiodiethanol, and a modified PET resin with an intrinsic viscosity of 0.82 dL / g and a refractive index of 1.552 is obtained in step (4). The other steps are the same, and the composite material is finally prepared.

[0087] Comparative Example 6:

[0088] The method and steps are the same as in Example 1, except that the sulfur-containing bisphenol diol monomer is replaced with sulfur-free bisphenol A ethoxylated diol (2,2-bis(4-(2-hydroxyethoxy)phenyl)propane) to prepare the modified PET resin. The refractive index of this modified PET is 1.573, which is 0.011 different from that of PC, exceeding the matching range of 0.01.

[0089] Comparative Example 7:

[0090] The steps are the same as in Example 1, except that no transesterification inhibitor is added. The other raw material ratios and preparation processes are completely consistent with those in Example 1, and a polyester composite material is finally prepared.

[0091] Comparative Example 8:

[0092] The steps are the same as in Example 1, except that the chain extender ADR4400 is not added. The other raw material ratios and preparation processes are completely consistent with those in Example 1, and a polyester composite material is finally prepared.

[0093] The performance of the polyester composite materials prepared in Examples 1-4 and Comparative Examples 1-8 was tested, and the results are shown in Table 1 below. The specific testing methods are as follows:

[0094] (1) Method for detecting heat distortion temperature: Refer to ISO 75 0.45 MPa method.

[0095] (2) Notched impact strength (KJ / m) 2 The testing method is as follows: refer to the method of ISO 180.

[0096] (3) The method for testing tensile strength (MPa) is as follows: refer to the method of ISO 527.

[0097] (4) The method for testing bending strength (MPa) is as follows: refer to the method of ISO 178.

[0098] (5) The test methods for transmittance (%) and haze (%) are as follows: refer to the method of ISO 13468.

[0099] Table 1 Test Results Data

[0100] The data above shows that the polyester composite materials prepared in Examples 1-4 have comparable mechanical properties to transparent ABS materials, and some indicators are even significantly better. Their light transmittance is also comparable to that of transparent ABS materials. In Comparative Example 1, because the PET was unmodified, its refractive index was only 1.55, which differed significantly from that of PC. Furthermore, its strong crystallinity and poor compatibility with amorphous PC resulted in a composite material with poor light transmittance, high haze, and moderate impact resistance. In Comparative Example 3, only the existing PET product was tested, and its impact resistance was significantly lower than that of ABS materials. In Comparative Example 4, the modified PET had a low viscosity, with an intrinsic viscosity of only 0.61 dL / g. This viscosity further decreased during co-extrusion with PC materials, leading to a decrease in its mechanical strength. In Comparative Example 5, the modified monomer contained only sulfur and no aromatic rings, making it impossible to achieve refractive index matching and structural compatibility between PET and PC. Therefore, it could not prepare a highly transparent, high-mechanical-performance alternative to transparent ABS composite material, resulting in a poor final product.

[0101] Comparative Example 6 results show that this comparative example used sulfur-free aromatic diol monomers to modify PET. Although an aromatic ring structure was introduced, the lack of sulfur atoms prevented the PET refractive index from reaching a range that matched that of PC. The refractive index difference between the two exceeded 0.01, leading to poor optical compatibility and significant light scattering. Ultimately, the material's transmittance decreased significantly, its haze increased substantially, its interfacial bonding weakened, and its notched impact strength decreased significantly, failing to meet the requirements for a high-transparency, high-impact alternative to transparent ABS.

[0102] Comparative Example 7 results show that, without the addition of an exchange transesterification inhibitor, excessive exchange transesterification occurred during the melt blending of modified PET and PC, leading to molecular chain breakage, a decrease in molecular weight, and overall material performance degradation. This manifested as a decrease in heat distortion temperature, a significant reduction in tensile / flexural strength, and a deterioration in notched impact strength. Simultaneously, excessive exchange transesterification disrupted the phase structure, resulting in increased haze and decreased light transmittance. This demonstrates that an exchange transesterification inhibitor is a crucial and indispensable additive for controlling the degree of reaction and maintaining mechanical and optical properties.

[0103] Comparative Example 8 shows that without the addition of chain extenders, the polymer molecular chains could not be effectively repaired and extended during the blending process, resulting in a lower molecular weight. The notched impact strength of the material decreased significantly, and the tensile and flexural strengths also decreased. However, due to refractive index matching and controlled transesterification, the transmittance and haze remained at good levels. This demonstrates that chain extenders are mainly used to increase molecular weight and improve toughness and mechanical strength, and are essential components for achieving high impact resistance and mechanical properties comparable to transparent ABS.

[0104] In summary, the polyester composite material of this invention is comparable to or even better than transparent ABS material in terms of light transmittance, heat resistance, and mechanical properties. For example... Figure 1 The DSC test results show that the addition of sulfur-containing monomer diol to the modified PET resin of this invention reduces its crystallinity and results in a non-crystalline form.

Claims

1. A polyester composite material, characterized in that, Contains the following raw materials by weight: 65-85 parts modified PET resin, 15-35 parts PC resin, 0.1-1 part transesterification inhibitor, 0.2-2 parts chain extender, 0.5-2 parts antioxidant, and 0.1-1 part lubricant; The modified PET resin is obtained by modifying PET resin with a sulfur-containing diol monomer; The difference in refractive index between the modified PET resin and the PC resin is within 0.

01.

2. The polyester composite material as described in claim 1, characterized in that, The modified PET resin has a refractive index of 1.58~1.585 and an intrinsic viscosity of 0.8~0.85 dL / g; the PC resin has a refractive index of 1.58~1.

59.

3. The polyester composite material as described in claim 1, characterized in that, The sulfur-containing diol monomer is a sulfur-containing bisphenol derivative; The PC resin is bisphenol A type polycarbonate; The transesterification inhibitor is selected from at least one of triphenyl phosphate, triphenyl phosphite, sodium dihydrogen phosphate, sodium hexametaphosphate, or disodium dihydrogen pyrophosphate. The chain extender is at least one of ADR4400, ADR4468 or chain extender 6059; The antioxidant is at least one of antioxidant 1010, antioxidant 1076, antioxidant 1315 or antioxidant 264; The lubricant is at least one of pentaerythritol stearate, stearyl stearate, or glyceryl monostearate.

4. The polyester composite material as described in claim 1, characterized in that, The sulfur-containing diol monomer is selected from... , , or At least one of them.

5. The polyester composite material as described in claim 1, characterized in that, The preparation method of the modified PET resin includes: Weigh out terephthalic acid, ethylene glycol, sulfur-containing glycol monomer and polycondensation catalyst, and carry out esterification reaction under an inert gas atmosphere. After the esterification reaction is completed when the esterification conversion rate reaches 90% or above, carry out prepolymerization reaction, then carry out polymerization reaction, discharge the material, and perform vacuum thickening in a rotary drum to obtain modified PET resin.

6. A polyester composite material as described in claim 5, characterized in that, The molar ratio of terephthalic acid, ethylene glycol, and sulfur-containing diol monomers is 1:0.8~1.2:0.1~0.4; The polycondensation catalyst is at least one of antimony-based, titanium-based, aluminum-based, or germanium-based catalysts; the amount of the polycondensation catalyst added is 100-500 ppm of the mass of terephthalic acid.

7. The polyester composite material as described in claim 5, characterized in that, The conditions for the esterification reaction are: pressure 0.1–0.4 MPa, stirring speed 50–120 r / min, and temperature 225–255℃; The conditions for the prepolymerization reaction are: reaction pressure 0.5~1 kPa, reaction temperature 240~265℃, and reaction time 40~60 min; The polymerization reaction conditions are: reaction pressure 10~300 Pa, reaction temperature 260~285℃, and reaction time 90~180 min.

8. The method for preparing a polyester composite material as described in claim 1, characterized in that, Includes the following steps: Weigh out dried modified PET resin and PC resin, ester exchange inhibitor, chain extender, lubricant and antioxidant, mix them evenly to obtain a mixture, melt blend and extrude to obtain polyester composite material.

9. The preparation method according to claim 8, characterized in that, The melt blending is carried out using a twin-screw extruder, wherein the screw temperature in the feeding section is 240-250℃, the screw temperature in the melting section is 250-260℃, and the screw temperature in the homogenization section is 260-268℃.

10. The application of the polyester composite material as described in claim 1 in the field of high transparency sheet materials.

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