A transparent and toughened PET material and its preparation method

Abstract

This invention relates to polymer materials, and discloses a transparent and toughened PET material and its preparation method. The material, by weight, comprises the following raw material components: 70-95 parts PET, 5-30 parts modified PCTG, and 0-0.01 parts antioxidant. The modified PCTG is obtained by polymerization of raw materials including ethylene glycol, terephthalic acid, 1,4-cyclohexanediol, and silver nanowires. The mass ratio of silver nanowires to ethylene glycol is 1:1-120. In this invention, a PCTG modified masterbatch containing an appropriate amount of silver nanowires is prepared by in-situ polymerization. This masterbatch is then melt-blended with PET to toughen and modify the PET. Utilizing the excellent compatibility of PCTG and PET, the toughness of PCTG, and the durability and light transmittance of silver nanowires, the toughness of PET can be significantly improved without affecting the transparency of PET itself. Furthermore, silver nanowires also possess excellent antibacterial properties; adding an appropriate amount of silver nanowires can give PET better antibacterial properties.

Description

Technical Field

[0001] This invention relates to polymer materials, specifically to a transparent and toughened PET material and its preparation method. Background Technology

[0002] Polyethylene terephthalate (PET) possesses good film-forming properties, optical transparency, mechanical properties, and impermeability, making it widely used in packaging materials. During processing, PET undergoes oxidation, hydrolysis, and strong shearing, leading to a decrease in its molecular weight and a significant decline in its mechanical properties, resulting in a marked increase in material brittleness. Therefore, minimizing the performance loss of PET during processing is crucial for improving the performance of its end products.

[0003] Currently, toughening transparent PET is generally achieved through modification by adding transparent small-molecule or oligomer toughening agents or nanomaterials, or through special post-processing techniques. The small-molecule or oligomer toughening agents typically used have reactive groups that can react with the terminal carboxyl groups in PET, thereby repairing its molecular chains. While this technology can, to some extent, splice together the PET molecular chains, thus improving the material's mechanical properties, it is not the only method that can achieve this.

[0004] For example, CN104341729A discloses a core-shell structure toughened PET material, whose components, by mass percentage, are: PET 70%–85%, inorganic rigid particles 8%–12%, diisocyanate 1%–2%, ethylene glycol 2%–4%, compatibilizer 3%–8%, nucleating agent 0.5%–2%, dispersant 0.1%–2%, and antioxidant 0.1%–1%. This invention uses diisocyanate and ethylene glycol in a mixer for stirring and addition polymerization to generate a polyurethane rubber elastomer, which is then coated on the surface of the inorganic rigid particles, forming a core-shell structure with the inorganic rigid particles as the core and the elastomer as the shell. This structure allows for a good combination and leverages the advantages of each component, resulting in a synergistic strengthening and toughening effect on the PET material, and also offers advantages such as good processing performance and low cost. However, the toughening agent is complex to design. As a cross-linking point of the PET molecular chain, this toughening agent often produces crystal points during the preparation of transparent PET products, thus affecting its downstream applications.

[0005] Besides adding toughening agents, the molecular chains of PET can also be repaired through solid-phase thickening (SSP) processing. SSP, also known as solid-phase polycondensation, is a polycondensation reaction that occurs in a solid state. The main principle of SSP is to heat PET particles with a certain molecular weight to a temperature above their glass transition temperature (usually between 10-40°C below their melting point), and then remove small molecule products under vacuum or inert gas protection (generally using high-purity nitrogen), allowing the polycondensation reaction to continue and thus further increasing the viscosity of PET. The viscosity of PET particles treated with SSP can increase from 0.6 dL / g to 1.1 dL / g or even higher.

[0006] For example, CN108084424A discloses a solid-state polymerization process for PET with high intrinsic viscosity. The process involves: S1. Pre-treating recycled PET raw materials and then melting them to obtain recycled PET melt; S2. Feeding the recycled PET melt into a disc rotor reactor or cage reactor, heating to melt the PET scraps to obtain PET melt, then adding a thickening and nucleating agent, stirring evenly, maintaining the temperature at 240-260 degrees Celsius, and holding for 40 minutes under nitrogen atmosphere for thickening; S3. Granulating the thickened and polymerized recycled PET melt to obtain recycled PET granules, which can then be used in the spinning process. This process produces polyester with an intrinsic viscosity ≥1.0 dL / g, exhibiting excellent properties such as high initial modulus, low heat shrinkage, fatigue resistance, and water resistance.

[0007] This technology primarily repairs the molecular chains by reacting the terminal carboxyl and hydroxyl groups of PET molecules at high temperatures. While this technology does not require additional additives, the entire reaction process demands complex equipment and precise process control, resulting in high energy consumption. Furthermore, the higher the viscosity of the PET, the lower its reaction efficiency. Summary of the Invention

[0008] This invention addresses the problems of significant brittleness and insufficient toughness in PET by providing a transparent and toughened PET material. PCTG, which is polymerized in situ from silver nanowires, is used as a toughening agent to achieve a highly efficient toughening effect on PET without affecting the transparency of the PET matrix, and also imparts antibacterial properties to the material.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0010] A transparent, toughened PET material, comprising the following raw material components by weight:

[0011] PET 70-95 parts

[0012] Modified PCTG 5-30 parts

[0013] Antioxidant 0-0.01 parts

[0014] The modified PCTG is obtained by polymerization of raw materials including ethylene glycol, terephthalic acid, 1,4-cyclohexanediol and silver nanowires; wherein the mass ratio of silver nanowires to ethylene glycol is 1:1-120.

[0015] In this invention, a PCTG modified masterbatch containing an appropriate amount of silver nanowires is prepared by in-situ polymerization. This masterbatch is then melt-blended with PET to toughen and modify the PET. On the one hand, PCTG has good compatibility with PET and excellent inherent toughness; on the other hand, silver nanowires possess excellent bending resistance and light transmittance. The silver nanowires in the in-situ polymerized modified PCTG are uniformly dispersed. Through the synergistic effect of these two factors, the toughness of PET can be significantly improved without affecting its transparency. Furthermore, silver nanowires also possess excellent antibacterial properties; adding an appropriate amount of silver nanowires can give PET good antibacterial properties.

[0016] Preferably, the mass ratio of the silver nanowires to ethylene glycol is 1:1-20; more preferably 1:1-1:10, such as 1:2, 1:2.5, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, or any value between them.

[0017] The silver nanowires have a diameter of 20–60 nm and a length of 10–60 μm, with an aspect ratio of 100–3000. The smaller the overall size of the silver nanowires, the better the dispersion, the better the toughening effect, and the higher the transparency.

[0018] Preferably, the silver nanowires have a diameter of 40-50 nm, a length of 20-50 μm, and an aspect ratio of 125-1000. If the aspect ratio is too large, severe entanglement and aggregation will occur between the silver nanowires, making uniform dispersion impossible and affecting the final properties of the material. If the aspect ratio is too small, the toughening effect will be reduced, and the final material properties will be lowered. When the aspect ratio is large, the silver nanowires are prone to self-entanglement, resulting in decreased dispersion uniformity and a weakened toughening effect.

[0019] The preparation process of the modified PCTG includes: mixing silver nanowires with ethylene glycol, then mixing with raw materials containing terephthalic acid and 1,4-cyclohexanediol, and polycondensing under the action of a catalyst to obtain the modified PCTG. In this invention, an in-situ polymerization method is used to first disperse the silver nanowires relatively uniformly in the PCTG polymer, and then blending with PET can achieve uniform dispersion of the silver nanowires in the PET. This in-situ polymerization pre-dispersion method can achieve more uniform dispersion of silver nanowires in the PET matrix, and its toughening effect is more prominent than that of direct melt blending. In this system, PCTG plays a dual role as a silver nanowire dispersant and a PET toughening agent, exhibiting excellent toughening effect.

[0020] The molar ratio of ethylene glycol, terephthalic acid, and 1,4-cyclohexanediol is 0.5:0.8:2-0.5:0.8:3.

[0021] The polycondensation reaction conditions are: under inert gas protection, at 240-270℃ and 0.25-0.3MPa pressure for 2-6 hours;

[0022] The catalyst includes one or more of titanium-based catalysts, antimony-based catalysts, and aluminum-based catalysts, and the amount of catalyst used is 0.01-1 wt% of the reactants.

[0023] Preferably, the titanium-based catalyst includes inorganic titanium salts (potassium hexafluorotitanate, potassium titanium oxalate, etc.) and organic titanium compounds (titanium esters, titanium carboxylate, etc.); the antimony-based catalyst includes antimony trioxide, antimony acetate, antimony glycolate, etc.; and the aluminum-based catalyst includes aluminum carboxylate, aluminate, and inorganic aluminum salts, etc.

[0024] The PET includes virgin PET or recycled PET; the intrinsic viscosity of the PET is 0.55-0.84 dl / g. Preferably, the intrinsic viscosity of the PET is 0.6-0.75 dl / g. Intrinsic viscosity test conditions: 25℃, solvent is phenol:tetrachloroethane = 1:1.

[0025] The intrinsic viscosity of the modified PCTG is 0.5–0.85 dl / g.

[0026] The antioxidant includes at least one of antioxidant 1010, antioxidant 168, antioxidant 1076, antioxidant 1098, and antioxidant 225.

[0027] The present invention also provides a method for preparing the transparent and toughened PET material, comprising the steps of: mixing raw materials including PET, modified PCTG and antioxidant, and melt extruding and granulating to obtain the transparent and toughened PET material.

[0028] The temperature for melt extrusion granulation is 210-260℃.

[0029] Preferably, the melt extrusion is carried out using a twin-screw extruder with a screw speed of 200-400 rpm.

[0030] Further optimization involves the twin-screw extruder having 8-10 temperature zones, such as 9, with temperature settings ranging from 210-230℃, 220-240℃, 225-245℃, 225-245℃, 230-250℃, 230-250℃, 230-250℃, 230-250℃, and 240-260℃.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) This invention prepares a PCTG modified masterbatch containing an appropriate amount of silver nanowires via in-situ polymerization, and then uses this masterbatch to melt-blend PET to toughen and modify it. Since silver nanowires possess excellent bending resistance and light transmittance, they do not affect the transparency of PET while providing toughening. Furthermore, silver nanowires also exhibit excellent antibacterial properties; adding an appropriate amount of silver nanowires can give PET better antibacterial properties.

[0033] (2) In this invention, PCTG is used as the carrier of toughening masterbatch. It has good compatibility with PET. At the same time, PCTG itself has excellent toughness. Blending the two can significantly improve the toughness of PET without affecting the transparency of PET itself.

[0034] (3) Silver nanowires and PCTG monomers are uniformly mixed by in-situ polymerization, and then polymerization is initiated to generate PCTG, which allows the silver nanowires to be uniformly dispersed in PCTG. Subsequently, this masterbatch is mixed with PET, which allows the silver nanowires to be uniformly dispersed in the PET matrix, thereby making its toughening effect more obvious. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Modifications or equivalent substitutions made by those skilled in the art based on their understanding of the technical solutions of this invention, without departing from the spirit and scope of the invention, should be covered within the protection scope of this invention.

[0036] All raw materials used in the following specific embodiments were purchased from the market. The PET grade was CZ-318, purchased from Sanfangxiang, Jiangsu Province, with an intrinsic viscosity of 0.8 dl / g. Silver nanowires of different sizes were purchased from Xianfeng Nano. Other chemical reagents were purchased from Aladdin Reagents.

[0037] The melt blending was carried out using a twin-screw extruder with nine temperature zones: 220℃ / 230℃ / 235℃ / 235℃ / 240℃ / 240℃ / 240℃ / 240℃ / 250℃, and the screw speed was 250~350rpm.

[0038] The tensile strength of the material was tested according to ASTM D638, the flexural strength according to ASTM D790, the notched impact strength according to ASTM D256, and the antibacterial test was conducted by culture method, with Escherichia coli and Staphylococcus aureus as the test species.

[0039] Example 1

[0040] Step 1, Preparation of modified PCTG:

[0041] Four parts of silver nanowires (aspect ratio of 1000, diameter of 40 nm, and length of 40 μm) were added to 80 parts of ethylene glycol (EG). The silver nanowires were uniformly dispersed in EG by ultrasound for 2 h to obtain EG containing silver nanowires.

[0042] Subsequently, terephthalic acid (PTA), silver nanowire-containing EG, 1,4-cyclohexanediol (CHDM), and a catalyst (potassium hexafluorotitanate) were added to a high-pressure reactor. The molar ratio of PTA:EG:CHDM was 0.5:0.8:2, and the catalyst was added at 0.01 wt.% of the total amount of all monomer raw materials. The materials were mixed uniformly by mechanical stirring for 10 minutes at a speed of 100 rpm. Then, nitrogen or argon gas was introduced to a pressure of 0.1 MPa, and the reactor temperature was raised to the reaction temperature. Esterification of the reactants began under the autocatalytic action of PTA. The reaction temperature was controlled at 250℃, and the reaction pressure at 0.3 MPa. After 2 hours of reaction, water began to be discharged. The esterification conversion rate was judged based on the amount of water discharged; esterification was considered complete when the amount of water discharged exceeded 90% of the theoretical value. The raw materials were then released from the polymerization reactor, granulated, and finally 280 parts of modified PCTG containing silver nanowires were obtained, with an characteristic viscosity of 0.84 dl / g.

[0043] Step 2, Preparation of transparent toughened PET material:

[0044] Take 10 parts of the modified PCTG prepared in step 1, 90 parts of PET particles, and 0.01 parts of antioxidant 1010 and add them to a high-speed mixer for mixing for 5 minutes. Then add them to a twin-screw extruder for melt blending, extrusion granulation, and finally obtain a transparent toughened PET material.

[0045] Example 2

[0046] Step 1, Preparation of modified PCTG:

[0047] Ten parts of silver nanowires (aspect ratio of 1000, diameter of 40 nm, and length of 40 μm) were added to 80 parts of ethylene glycol (EG). The silver nanowires were uniformly dispersed in EG by ultrasound for 2 hours to obtain EG containing silver nanowires.

[0048] Subsequently, terephthalic acid (PTA), silver nanowire-containing EG, 1,4-cyclohexanediol (CHDM), and a catalyst (potassium hexafluorotitanate) were added to a high-pressure reactor. The molar ratio of PTA:EG:CHDM was 0.5:0.8:2, and the catalyst was added at 0.01 wt.% of the total amount of all monomer raw materials. The materials were mixed uniformly by mechanical stirring for 10 minutes at a speed of 100 rpm. Then, nitrogen or argon gas was introduced to a pressure of 0.1 MPa, and the reactor temperature was raised to the reaction temperature. Esterification of the reactants began under the autocatalytic action of PTA. The reaction temperature was controlled at 250℃, and the reaction pressure was controlled at 0.3 MPa. Water began to be discharged after 2 hours of reaction. The esterification conversion rate was judged based on the amount of water discharged. Esterification was considered complete when the amount of water discharged exceeded 90% of the theoretical value. The raw materials were then released from the polymerization reactor, granulated, and finally 285 parts of modified PCTG containing silver nanowires were obtained, with an characteristic viscosity of 0.84 dl / g.

[0049] Step 2, Preparation of transparent toughened PET material:

[0050] Take 10 parts of the modified PCTG prepared in step 1, 90 parts of PET particles, and 0.01 parts of antioxidant 1010 and add them to a high-speed mixer for mixing for 5 minutes. Then add them to a twin-screw extruder for melt blending, extrusion granulation, and finally obtain a transparent toughened PET material.

[0051] Example 3

[0052] Step 1, Preparation of modified PCTG:

[0053] Twenty parts of silver nanowires (aspect ratio of 1000, diameter of 40 nm, and length of 40 μm) were added to 80 parts of ethylene glycol (EG). The silver nanowires were uniformly dispersed in EG by ultrasound for 2 hours to obtain EG containing silver nanowires.

[0054] Subsequently, terephthalic acid (PTA), silver nanowire-containing EG, 1,4-cyclohexanediol (CHDM), and a catalyst (potassium hexafluorotitanate) were added to a high-pressure reactor. The molar ratio of PTA:EG:CHDM was 0.5:0.8:2, and the catalyst was added at 0.01 wt.% of the total amount of all monomer raw materials. The materials were mixed uniformly by mechanical stirring for 10 minutes at a speed of 100 rpm. Then, nitrogen or argon gas was introduced to a pressure of 0.1 MPa, and the reactor temperature was raised to the reaction temperature. Esterification of the reactants began under the autocatalytic action of PTA. The reaction temperature was controlled at 250℃, and the reaction pressure at 0.3 MPa. After 2 hours of reaction, water began to be discharged. The esterification conversion rate was judged based on the amount of water discharged; esterification was considered complete when the amount of water discharged exceeded 90% of the theoretical value. The raw materials were then released from the polymerization reactor, granulated, and finally 290 parts of modified PCTG containing silver nanowires were obtained, with an characteristic viscosity of 0.83 dl / g.

[0055] Step 2, Preparation of transparent toughened PET material:

[0056] Take 10 parts of the modified PCTG prepared in step 1, 90 parts of PET particles, and 0.01 parts of antioxidant 1010 and add them to a high-speed mixer for mixing for 5 minutes. Then add them to a twin-screw extruder for melt blending, extrusion granulation, and finally obtain a transparent toughened PET material.

[0057] Example 4

[0058] Step 1, Preparation of modified PCTG:

[0059] 30 parts of silver nanowires (aspect ratio of 1000, diameter of 40 nm, and length of 40 μm) were added to 80 parts of ethylene glycol (EG). The silver nanowires were uniformly dispersed in EG by ultrasound for 2 h to obtain EG containing silver nanowires.

[0060] Subsequently, terephthalic acid (PTA), silver nanowire-containing EG, 1,4-cyclohexanediol (CHDM), and a catalyst (potassium hexafluorotitanate) were added to a high-pressure reactor. The molar ratio of PTA:EG:CHDM was 0.5:0.8:2, and the catalyst was added at 0.01 wt.% of the total amount of all monomer raw materials. The materials were mixed uniformly by mechanical stirring for 10 minutes at a speed of 100 rpm. Then, nitrogen or argon gas was introduced to a pressure of 0.1 MPa, and the reactor temperature was raised to the reaction temperature. Esterification of the reactants began under the autocatalytic action of PTA. The reaction temperature was controlled at 250℃, and the reaction pressure at 0.3 MPa. After 2 hours of reaction, water began to be discharged. The esterification conversion rate was judged based on the amount of water discharged; esterification was considered complete when the amount of water discharged exceeded 90% of the theoretical value. The raw materials were then released from the polymerization reactor, granulated, and finally 296 portions of modified PCTG containing silver nanowires were obtained, with an characteristic viscosity of 0.84 dl / g.

[0061] Step 2, Preparation of transparent toughened PET material:

[0062] Take 10 parts of the modified PCTG prepared in step 1, 90 parts of PET particles, and 0.01 parts of antioxidant 1010 and add them to a high-speed mixer for mixing for 5 minutes. Then add them to a twin-screw extruder for melt blending, extrusion granulation, and finally obtain a transparent toughened PET material.

[0063] Example 5

[0064] Step 1, Preparation of modified PCTG:

[0065] Twenty parts of silver nanowires (aspect ratio of 3000, diameter of 20 nm, and length of 60 μm) were added to 80 parts of ethylene glycol (EG). The silver nanowires were uniformly dispersed in EG by ultrasound for 2 hours to obtain EG containing silver nanowires.

[0066] Subsequently, terephthalic acid (PTA), silver nanowire-containing EG, 1,4-cyclohexanediol (CHDM), and a catalyst (potassium hexafluorotitanate) were added to a high-pressure reactor. The molar ratio of PTA:EG:CHDM was 0.5:0.8:2, and the catalyst was added at 0.01 wt.% of the total amount of all monomer raw materials. The materials were mixed uniformly by mechanical stirring for 10 minutes at a speed of 100 rpm. Then, nitrogen or argon gas was introduced to a pressure of 0.1 MPa, and the reactor temperature was raised to the reaction temperature. Esterification of the reactants began under the autocatalytic action of PTA. The reaction temperature was controlled at 250℃, and the reaction pressure at 0.3 MPa. After 2 hours of reaction, water began to be discharged. The esterification conversion rate was judged based on the amount of water discharged; esterification was considered complete when the amount of water discharged exceeded 90% of the theoretical value. The raw materials were then released from the polymerization reactor, granulated, and finally 290 parts of modified PCTG containing silver nanowires were obtained, with an characteristic viscosity of 0.82 dl / g.

[0067] Step 2, Preparation of transparent toughened PET material:

[0068] Take 10 parts of the modified PCTG prepared in step 1, 90 parts of PET particles, and 0.01 parts of antioxidant 1010 and add them to a high-speed mixer for mixing for 5 minutes. Then add them to a twin-screw extruder for melt blending, extrusion granulation, and finally obtain a transparent toughened PET material.

[0069] Example 6

[0070] Step 1, Preparation of modified PCTG:

[0071] Twenty parts of silver nanowires (aspect ratio of 167, diameter of 60 nm, and length of 10 μm) were added to 80 parts of ethylene glycol (EG). The silver nanowires were uniformly dispersed in EG by ultrasound for 2 hours to obtain EG containing silver nanowires.

[0072] Subsequently, terephthalic acid (PTA), silver nanowire-containing EG, 1,4-cyclohexanediol (CHDM), and a catalyst (potassium hexafluorotitanate) were added to a high-pressure reactor. The molar ratio of PTA:EG:CHDM was 0.5:0.8:2, and the catalyst was added at 0.01 wt.% of the total amount of all monomer raw materials. The materials were mixed uniformly by mechanical stirring for 10 minutes at a speed of 100 rpm. Then, nitrogen or argon gas was introduced to a pressure of 0.1 MPa, and the reactor temperature was raised to the reaction temperature. Esterification of the reactants began under the autocatalytic action of PTA. The reaction temperature was controlled at 250℃, and the reaction pressure was controlled at 0.3 MPa. Water began to be discharged after 2 hours of reaction. The esterification conversion rate was judged based on the amount of water discharged. Esterification was considered complete when the amount of water discharged exceeded 90% of the theoretical value. The raw materials were then released from the polymerization reactor, granulated, and finally 290 parts of modified PCTG containing silver nanowires were obtained, with an characteristic viscosity of 0.82 dl / g.

[0073] Step 2, Preparation of transparent toughened PET material:

[0074] Take 10 parts of the modified PCTG prepared in step 1, 90 parts of PET particles, and 0.01 parts of antioxidant 1010 and add them to a high-speed mixer for mixing for 5 minutes. Then add them to a twin-screw extruder for melt blending, extrusion granulation, and finally obtain a transparent toughened PET material.

[0075] Example 7

[0076] Step 1, Preparation of modified PCTG:

[0077] Twenty parts of silver nanowires (aspect ratio of 1000, diameter of 40 nm, and length of 40 μm) were added to 80 parts of ethylene glycol (EG). The silver nanowires were uniformly dispersed in EG by ultrasound for 2 hours to obtain EG containing silver nanowires.

[0078] Subsequently, terephthalic acid (PTA), silver nanowire-containing EG, 1,4-cyclohexanediol (CHDM), and a catalyst (potassium hexafluorotitanate) were added to a high-pressure reactor. The molar ratio of PTA:EG:CHDM was 0.5:0.8:2, and the catalyst was added at 0.01 wt.% of the total amount of all monomer raw materials. The materials were mixed uniformly by mechanical stirring for 10 minutes at a speed of 100 rpm. Then, nitrogen or argon gas was introduced to a pressure of 0.1 MPa, and the reactor temperature was raised to the reaction temperature. Esterification of the reactants began under the autocatalytic action of PTA. The reaction temperature was controlled at 250℃, and the reaction pressure was controlled at 0.3 MPa. Water began to be discharged after 2 hours of reaction. The esterification conversion rate was judged based on the amount of water discharged. Esterification was considered complete when the amount of water discharged exceeded 90% of the theoretical value. The raw materials were then released from the polymerization reactor, granulated, and finally 290 parts of modified PCTG containing silver nanowires were obtained, with an characteristic viscosity of 0.83 dl / g.

[0079] Step 2, Preparation of transparent toughened PET material:

[0080] Take 20 parts of the modified PCTG prepared in step 1, 90 parts of PET particles, and 0.01 parts of antioxidant 1010 and add them to a high-speed mixer for mixing for 5 minutes. Then add them to a twin-screw extruder for melt blending, extrusion granulation, and finally obtain a transparent toughened PET material.

[0081] Example 8

[0082] Step 1, Preparation of modified PCTG:

[0083] Twenty parts of silver nanowires (aspect ratio of 1000, diameter of 40 nm, and length of 40 μm) were added to 80 parts of ethylene glycol (EG). The silver nanowires were uniformly dispersed in EG by ultrasound for 2 hours to obtain EG containing silver nanowires.

[0084] Subsequently, terephthalic acid (PTA), silver nanowire-containing EG, 1,4-cyclohexanediol (CHDM), and a catalyst (potassium hexafluorotitanate) were added to a high-pressure reactor. The molar ratio of PTA:EG:CHDM was 0.5:0.8:2, and the catalyst was added at 0.01 wt.% of the total amount of all monomer raw materials. The materials were mixed uniformly by mechanical stirring for 10 minutes at a speed of 100 rpm. Then, nitrogen or argon gas was introduced to a pressure of 0.1 MPa, and the reactor temperature was raised to the reaction temperature. Esterification of the reactants began under the autocatalytic action of PTA. The reaction temperature was controlled at 250℃, and the reaction pressure was controlled at 0.3 MPa. Water began to be discharged after 2 hours of reaction. The esterification conversion rate was judged based on the amount of water discharged. Esterification was considered complete when the amount of water discharged exceeded 90% of the theoretical value. The raw materials were then released from the polymerization reactor, granulated, and finally 290 parts of modified PCTG containing silver nanowires were obtained, with an characteristic viscosity of 0.82 dl / g.

[0085] Step 2, Preparation of transparent toughened PET material:

[0086] Take 30 parts of the modified PCTG prepared in step 1, 90 parts of PET particles, and 0.01 parts of antioxidant 1010 and add them to a high-speed mixer for mixing for 5 minutes. Then add them to a twin-screw extruder for melt blending, extrusion granulation, and finally obtain a transparent toughened PET material.

[0087] Comparative Example 1

[0088] Terephthalic acid (PTA), EG, 1,4-cyclohexanediol (CHDM), and a catalyst (potassium hexafluorotitanate) were added to a high-pressure reactor. The molar ratio of PTA:EG:CHDM was 0.5:0.8:2, and the catalyst was added at 0.01 wt.% of the total monomer raw materials. The materials were mixed uniformly by mechanical stirring for 10 minutes at 100 rpm. Nitrogen or argon gas was then introduced to a pressure of 0.1 MPa, and the reactor temperature was raised to the reaction temperature. Esterification of the reactants began under the autocatalytic action of PTA. The reaction temperature was controlled at 250℃, and the reaction pressure at 0.3 MPa. After 2 hours of reaction, water began to be discharged. The esterification conversion rate was judged based on the amount of water discharged; esterification was considered complete when the amount of water exceeded 90% of the theoretical value. The raw materials were then discharged from the polymerization reactor, pelletized, and finally, in-situ polymerized PCTG was obtained, with a characteristic viscosity of 0.84 dl / g.

[0089] 0.7 parts silver nanowires, 9.3 parts PCTG particles, 90 parts PET particles, and 0.01 parts antioxidant 1010 were added to a high-speed mixer and mixed for 5 minutes. The mixture was then fed into a twin-screw extruder for melt blending, extruded, and granulated to obtain a transparent, toughened PET material.

[0090] Comparative Example 2

[0091] Terephthalic acid (PTA), ethylene glycol (EG), 1,4-cyclohexanediol (CHDM), and a catalyst (potassium hexafluorotitanate) were added to a high-pressure reactor. The molar ratio of PTA:EG:CHDM was 0.5:0.8:2, and the catalyst was added at 0.01 wt.% of the total monomer raw materials. The materials were mixed uniformly by mechanical stirring for 10 minutes at 100 rpm. Nitrogen or argon gas was then introduced to a pressure of 0.1 MPa, and the reactor temperature was raised to the reaction temperature. Esterification of the reactants began under the autocatalytic action of PTA. The reaction temperature was controlled at 250℃, and the reaction pressure at 0.3 MPa. After 2 hours of reaction, water began to be discharged. The esterification conversion rate was judged based on the amount of water discharged; esterification was considered complete when the amount of water exceeded 90% of the theoretical value. The raw materials were then discharged from the polymerization reactor, pelletized, and finally, in-situ polymerized PCTG was obtained, with an characteristic viscosity of 0.84 dl / g.

[0092] 10 parts PCTG, 90 parts PET particles, and 0.01 parts antioxidant 1010 were added to a high-speed mixer and mixed for 5 minutes. The mixture was then fed into a twin-screw extruder for melt blending, extrusion granulation, and finally yielded a transparent, toughened PET material.

[0093] Comparative Example 3

[0094] 50 parts of the modified PCTG prepared in Example 4, 50 parts of PET particles, and 0.01 parts of antioxidant 1010 were added to a high-speed mixer and mixed for 5 minutes. The mixture was then fed into a twin-screw extruder for melt blending, extruded, and granulated to obtain a transparent, toughened PET material.

[0095] The mechanical properties, transparency, and antibacterial properties of the materials in the examples and comparative examples were tested, and the results are shown in Table 1.

[0096] Table 1. Performance of PET materials in the examples and comparative examples.

[0097]

[0098] As can be seen from the data in Table 1, in Examples 1-4, the amount of silver nanowires in the modified PCTG was continuously increased. Under the same amount of modified PCTG added, the mechanical properties of the PET product were initially improved, and then gradually decreased. As for transparency, the more the amount added, the more obvious the effect became, but the overall effect was relatively small.

[0099] As seen in Examples 1, 5, and 6, increasing the aspect ratio of silver nanowires to a certain extent can effectively improve the toughness of the product. Similarly, increasing the amount of modified PCTG can also improve the toughness and mechanical strength of the product to a certain extent, but too much can be detrimental and affect the transparency of the product.

[0100] As can be seen from Examples 3 and Comparative Examples 1 and 2, with the same raw materials, if the direct blending of Comparative Example 1 is used, the effect is significantly different from the blending after in-situ polymerization in Example 1. The reason is that the silver nanowires agglomerate during the melt blending process without PCTG pre-dispersion treatment, and the final toughening effect is not reflected.

[0101] In Comparative Example 2, without the addition of silver nanoparticles, the toughening effect decreased compared to Example 3 with the same amount, with an impact strength reduction of approximately 50%. Simultaneously, tensile and flexural properties also significantly decreased. This indicates that the addition of silver nanowires significantly contributes to the improvement of the material's mechanical properties. Comparative Example 3, with the addition of excessive silver nanowires, ultimately led to a decrease in the material's mechanical properties, light transmittance, and antibacterial properties. This is because high-content silver nanowires tend to aggregate in the PET matrix, making it difficult to achieve uniform dispersion within the PET matrix.

Claims

1. A transparent toughened PET material, characterized in that, According to the quality parts, including the following raw material components: PET 70-95 parts Modified PCTG 5-30 parts Antioxidant 0-0.01 parts The modified PCTG is obtained by polymerization of raw materials including ethylene glycol, terephthalic acid, 1,4-cyclohexanedimethanol and silver nanowire; the molar ratio of ethylene glycol, terephthalic acid, 1,4-cyclohexanedimethanol is 0.5:0.8:2-0.5:0.8:3; The mass ratio of silver nanowire to ethylene glycol is 1:1-10; The silver nanowire has a diameter of 40-50 nm, a length of 20-50 um, and an aspect ratio of 125-1000; the preparation process of the modified PCTG includes: mixing silver nanowire with ethylene glycol, mixing with raw materials containing terephthalic acid and 1,4-cyclohexanedimethanol, and polycondensation under the action of a catalyst to obtain the modified PCTG.

2. The transparent toughened PET material according to claim 1, wherein, The polycondensation reaction conditions are: under the protection of inert gas, at 240-270℃, under the pressure of 0.25-0.3 MPa, for 2-6h; And / or, the catalyst includes one or more of titanium-based catalyst, antimony-based catalyst, aluminum-based catalyst, and the catalyst is used in an amount of 0.01-1wt% of the reaction raw materials.

3. The transparent toughened PET material according to claim 1, wherein, The PET includes virgin PET or recycled PET; And / or, the intrinsic viscosity of the PET is 0.55-0.84dl / g.

4. The transparent toughened PET material according to claim 1, wherein, The intrinsic viscosity of the modified PCTG is 0.5-0.85dl / g.

5. The transparent toughened PET material according to claim 1, wherein, The antioxidant includes at least one of antioxidant 1010, antioxidant 168, antioxidant 1076, antioxidant 1098, and antioxidant 225.

6. The process for the preparation of transparent toughened PET material according to any one of claims 1 to 5, characterized in that, The method includes the steps of mixing, melting extruding and granulating the raw materials including PET, modified PCTG and antioxidant to obtain the transparent and toughened PET material.

7. The method for preparing the transparent and toughened PET material according to claim 6, characterized in that, The temperature for melting extrusion and granulation is 210-260℃.

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