A foaming modifier for polybutylene adipate terephthalate and use thereof

Abstract

The present application relates to a kind of foaming modifier of polybutylene terephthalate and its application, belong to foaming technical field.The present application provides a kind of foaming modifier of polybutylene terephthalate, the component of the foaming modifier includes polybutylene succinate, antioxidant, nucleating agent and chain extender;In the foaming modifier, the mass ratio of polybutylene succinate, antioxidant, nucleating agent and chain extender is 1~3:0.01~0.05:0.1~0.5:0.1~0.5.Use the foaming modifier of the present application to modify polybutylene terephthalate, can widen the processing temperature of material, it is convenient to hot-pressing forming, can improve the entanglement of molecular chain, thereby guarantee the melt strength of foaming embryo, improve the crystallization behavior of material, and, can relieve the cell shrinkage brought after foaming, and then for the final product realizes environment-friendly cycle and excellent dynamic performance provides key support.

Description

Technical Field

[0001] This invention relates to a foaming modifier for polybutylene terephthalate and its application, belonging to the field of foaming technology. Background Technology

[0002] Supercritical physical foaming is an advanced foaming process characterized by its environmental friendliness and superior performance of the resulting foamed products. In recent years, it has garnered significant attention in the manufacture of sports equipment, such as shoe midsoles. This process utilizes the high solubility and low viscosity of supercritical fluids to create a uniformly distributed, micro-sized porous structure within the substrate. This allows the foamed products to achieve lightweight construction while possessing excellent elastic recovery, sound insulation, thermal insulation, and cushioning properties. Compared to traditional chemical foaming processes, supercritical physical foaming offers superior environmental friendliness, production efficiency, and product performance. Furthermore, it allows for more precise control of cell morphology, thereby optimizing the overall performance of the product.

[0003] However, currently, most sports equipment, such as shoe midsoles, are made from materials like TPEE, TPU, and PEBA through supercritical physical foaming. After disposal, these materials often face the challenge of recycling and reuse, ultimately ending up in landfills or incineration. Landfilling these polymeric wastes not only occupies land resources but can also cause long-term pollution to the soil and surrounding environment. Furthermore, the materials are difficult to degrade naturally, further exacerbating the burden of "white pollution." Incineration, on the other hand, easily releases harmful gases, negatively impacting the atmospheric environment.

[0004] Polybutylene terephthalate (PBAT) is a copolyester prepared using butylene terephthalate and butylene adipate as monomers. Its structure combines biodegradability with excellent tensile elongation, enabling it to gradually degrade into water and carbon dioxide in composting or natural environments as a bio-based biodegradable material. Supercritical carbon dioxide foaming effectively ensures the green and environmentally friendly production process and subsequent recycling. However, PBAT foamed products obtained using supercritical carbon dioxide foaming generally suffer from severe cell shrinkage, poor performance, and difficulties in hot-pressing due to the significant carbon dioxide pressure difference between the inside and outside of the cells, as well as the inherent poor elasticity, low melt strength, and low heat distortion temperature of PBAT material. Summary of the Invention

[0005] To address the aforementioned deficiencies, this invention provides a foaming modifier for polybutylene terephthalate (PBS), wherein the foaming modifier comprises PBS, an antioxidant, a nucleating agent, and a chain extender; wherein the mass ratio of PBS, antioxidant, nucleating agent, and chain extender in the foaming modifier is 1~3:0.01~0.05:0.1~0.5:0.1~0.5.

[0006] In one embodiment of the present invention, the antioxidant comprises antioxidant 1010 (pentaerythritol tetrakis(β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), antioxidant 1076 (octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), and / or antioxidant 9228 (bis(2,4-dicumylphenyl)pentaerythritol-diphosphite); the nucleating agent comprises talc; and the chain extender comprises chain extender ADR-4468 and / or chain extender SG-20.

[0007] The present invention also provides a foamed preform, the composition of which includes polybutylene adipate terephthalate (PBAT) and the above-mentioned foaming modifier.

[0008] In one embodiment of the present invention, the mass ratio between polybutylene adipate and foaming modifier in the foamed preform is 5.95~8.79:1.21~4.05.

[0009] In one embodiment of the present invention, the method for preparing the foamed preform includes: mixing polybutylene adipate terephthalate and a foaming modifier and then molding to obtain a foamed preform.

[0010] In one embodiment of the present invention, the method for preparing the foamed preform includes: mixing polybutylene adipate terephthalate, polybutylene succinate, antioxidant, nucleating agent and chain extender and then granulating to obtain a modified masterbatch; and molding the modified masterbatch to obtain a foamed preform.

[0011] In one embodiment of the present invention, the method for preparing the foamed preform includes: mixing polybutylene adipate terephthalate, polybutylene succinate, antioxidant, nucleating agent and chain extender, then melting and blending them first through a twin-screw extruder, and then granulating them through a cutting machine to obtain a modified masterbatch; and then injection molding the modified masterbatch through an injection molding machine to obtain a foamed preform (i.e., an injection-molded preform).

[0012] In one embodiment of the present invention, the method for preparing the foamed preform includes: drying and premixing polybutylene adipate, polybutylene succinate, antioxidant, nucleating agent and chain extender to obtain mixture A; melting and blending mixture A first through a twin-screw extruder, and then granulating it after cooling through a cutting machine to obtain modified masterbatch; and then dehumidifying and drying the modified masterbatch and injection molding it through an injection molding machine to obtain the foamed preform.

[0013] In one embodiment of the present invention, the temperature of the melt blending is 160~180°C.

[0014] The present invention also provides a method for preparing the above-mentioned foamed preform, the method comprising: mixing polybutylene adipate terephthalate and a foaming modifier and then molding to obtain a foamed preform.

[0015] In one embodiment of the present invention, the method includes: mixing polybutylene adipate terephthalate, polybutylene succinate, antioxidant, nucleating agent and chain extender and then granulating to obtain a modified masterbatch; and molding the modified masterbatch to obtain a foamed preform.

[0016] In one embodiment of the present invention, the method includes: mixing polybutylene adipate terephthalate, polybutylene succinate, antioxidant, nucleating agent and chain extender, then melting and blending them first through a twin-screw extruder, and then granulating them through a cutting machine to obtain a modified masterbatch; and then injection molding the modified masterbatch through an injection molding machine to obtain a foamed preform (i.e., an injection-molded preform).

[0017] In one embodiment of the present invention, the method includes: drying and premixing polybutylene adipate terephthalate, polybutylene succinate, antioxidant, nucleating agent and chain extender to obtain mixture A; melting and blending mixture A first through a twin-screw extruder, and then granulating it after cooling through a cutting machine to obtain modified masterbatch; and then injection molding the modified masterbatch after dehumidification and drying through an injection molding machine to obtain foamed preform.

[0018] In one embodiment of the present invention, the temperature of the melt blending is 160~180°C.

[0019] The present invention also provides a foamed product, which is obtained by foaming the above-mentioned foamed preform.

[0020] In one embodiment of the present invention, the method for preparing the foamed product includes: placing a foamed preform in a foaming container at a foaming temperature, and introducing a physical foaming agent into the foaming container until the pressure inside the foaming container reaches the foaming pressure; continuously placing the foamed preform in the foaming container at the foaming pressure and the foaming temperature until the physical foaming agent reaches a dissolution equilibrium in the foamed preform; releasing the pressure inside the foaming container to the ambient pressure to induce the nucleation and growth of cells, thereby causing the foamed preform to foam and obtain the foamed product.

[0021] In one embodiment of the present invention, the physical foaming agent comprises supercritical carbon dioxide fluid and / or supercritical nitrogen fluid.

[0022] In one embodiment of the present invention, the physical foaming agent is composed of supercritical carbon dioxide fluid and supercritical nitrogen fluid; the pressure ratio of the supercritical carbon dioxide fluid and the supercritical nitrogen fluid in the physical foaming agent is 10~20:4~8.

[0023] In one embodiment of the present invention, the foaming temperature is 100~120℃; the foaming pressure is 15~25MPa; the time to reach dissolution equilibrium is 120~150min; and the average depressurization rate is 2~5MPa / s.

[0024] In one embodiment of the present invention, the foamed product includes a foamed shoe material midsole or a foamed sheet.

[0025] The present invention also provides a method for preparing the above-mentioned foamed product, the method comprising: foaming the above-mentioned foamed preform to obtain the foamed product.

[0026] In one embodiment of the present invention, the method includes: placing a foamed preform in a foaming container at a foaming temperature, and introducing a physical foaming agent into the foaming container until the pressure inside the foaming container reaches the foaming pressure; continuously placing the foamed preform in the foaming container at the foaming pressure and the foaming temperature until the physical foaming agent reaches a dissolution equilibrium in the foamed preform; releasing the pressure inside the foaming container to ambient pressure to induce the nucleation and growth of cells, thereby causing the foamed preform to foam and obtain a foamed product.

[0027] In one embodiment of the present invention, the physical foaming agent comprises supercritical carbon dioxide fluid and / or supercritical nitrogen fluid.

[0028] In one embodiment of the present invention, the physical foaming agent is composed of supercritical carbon dioxide fluid and supercritical nitrogen fluid; the pressure ratio of the supercritical carbon dioxide fluid and the supercritical nitrogen fluid in the physical foaming agent is 10~20:4~8.

[0029] In one embodiment of the present invention, the foaming temperature is 100~120℃; the foaming pressure is 15~25MPa; the time to reach dissolution equilibrium is 120~150min; and the average depressurization rate is 2~5MPa / s.

[0030] In one embodiment of the present invention, the foamed product includes a foamed shoe midsole or a foamed sheet.

[0031] The present invention also provides the application of the above-mentioned foaming modifier or the above-mentioned foaming preform in the preparation of foamed products.

[0032] In one embodiment of the present invention, the foamed product includes a foamed shoe midsole or a foamed sheet.

[0033] The technical solution of this invention has the following advantages: 1. This invention provides a foaming modifier for polybutylene terephthalate (PBAT), comprising PBAT, an antioxidant, a nucleating agent, and a chain extender. The mass ratio of PBAT, antioxidant, nucleating agent, and chain extender in the foaming modifier is 1-3:0.01-0.05:0.1-0.5:0.1-0.5. This foaming modifier is based on a PBAT blending modification strategy. Modifying PBAT with this foaming modifier can broaden the material's processing temperature range, facilitate hot pressing, improve molecular chain entanglement, thus ensuring the melt strength of the foamed preform, improve the material's crystallization behavior, and alleviate cell shrinkage after foaming. This provides crucial support for achieving environmentally friendly recycling and excellent dynamic performance in the final product.

[0034] 2. This invention provides a foamed preform, the components of which include polybutylene adipate terephthalate (PBAT) and a foaming modifier; the foaming modifier comprises polybutylene succinate, an antioxidant, a nucleating agent, and a chain extender; the mass ratio of polybutylene succinate, antioxidant, nucleating agent, and chain extender in the foaming modifier is 1~3:0.01~0.05:0.1~0.5:0.1~0.5. The foamed preform of this invention possesses a synergistic and stable composite system. This stable composite system can effectively broaden the processing temperature of the material, facilitate hot pressing, effectively improve the entanglement of molecular chains, thereby ensuring the melt strength of the foamed preform, improving the crystallization behavior of the material, and effectively mitigating cell shrinkage after foaming, thus providing key support for achieving environmentally friendly recycling and excellent dynamic performance in the final product.

[0035] 3. This invention provides a foamed product, characterized in that the foamed product is obtained by foaming a foamed preform; the foamed preform comprises polybutylene adipate terephthalate (PBAT) and a foaming modifier; the foaming modifier comprises polybutylene succinate, an antioxidant, a nucleating agent, and a chain extender; in the foaming modifier, the mass ratio of polybutylene succinate, antioxidant, nucleating agent, and chain extender is 1~3:0.01~0.05:0.1~0.5:0.1~0.5. Studies have shown that the foamed product of this invention has characteristics such as low density, high hardness, good resilience, high elongation, and good delamination and tear resistance, exhibiting superior performance.

[0036] Further, the method for preparing the foamed product includes: placing a foamed preform in a foaming container at the foaming temperature, and introducing a physical foaming agent into the foaming container until the pressure inside the container reaches the foaming pressure; continuously placing the foamed preform in the foaming container at the foaming pressure and foaming temperature until the physical foaming agent reaches a dissolution equilibrium in the foamed preform; releasing the pressure inside the foaming container to ambient pressure to induce cell nucleation and growth, causing the foamed preform to foam, thereby obtaining the foamed product; the physical foaming agent is composed of supercritical carbon dioxide fluid and supercritical nitrogen fluid; the pressure ratio of the supercritical carbon dioxide fluid to the supercritical nitrogen fluid in the physical foaming agent is 10~20:4~8. The method for preparing the foamed product improves the foaming temperature window and reduces cell shrinkage by adjusting the ratio of CO2 and N2 in the physical foaming agent, achieving a high foaming ratio and fulfilling the goal of lightweight foamed products. Attached Figure Description

[0037] Figure 1 Example 3-1: Foam cell structure of the midsole of the foamed shoe material (before hot pressing).

[0038] Figure 2 Photograph of the foamed shoe material midsole obtained in Comparative Example 3-1 (after hot pressing and shaping).

[0039] Figure 3 Comparative Example 3-2: Foam cell structure of the midsole of the foamed shoe material (before hot pressing).

[0040] Figure 4 Comparative Example 3-3: Foam cell structure of the midsole of the foamed shoe material (before hot pressing).

[0041] Figure 5 Photographs of the foamed shoe material midsole obtained in Comparative Examples 3-4 (before hot pressing and shaping).

[0042] Figure 6 Photographs of the foamed shoe material midsole obtained in Comparative Examples 3-5 (before hot pressing and shaping).

[0043] Figure 7 Photographs of the foamed shoe material midsole obtained in Comparative Examples 3-6 (before hot pressing and shaping).

[0044] Figure 8 Photographs of the foamed shoe material midsole obtained in Comparative Examples 3-7 (before hot pressing and shaping). Detailed Implementation

[0045] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0046] For any experimental steps or conditions not specified in the following examples, the procedures or conditions described in the literature in this field can be followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0047] The polybutylene adipate (PBAT) used in the following examples was purchased from Huafeng Company. Under composting conditions, it can be decomposed into carbon dioxide, water, and biomass by microorganisms within 180 days, meeting the requirements of Chinese GB / T 28206, European EN13432, American ASTM D6400, and other biodegradable material standards. The melt flow index is 10~15g / 10min (test conditions: 190℃, 2.16kg weight). The polybutylene succinate (PBS) used in the following examples was purchased from Shandong Landian Biotechnology Co., Ltd., the transparent talc powder was purchased from Shanxi Chemical Research Institute, and the antioxidants 9228, 1076, and chain extender ADR-4468 were purchased from BASF.

[0048] Example 1-1: A foaming modifier for polybutylene terephthalate (PET) This embodiment provides a foaming modifier for polybutylene terephthalate (PBS), which is composed of PBS (polybutylene succinate) in a mass ratio of 2:0.05:0.5:0.5, antioxidants (antioxidant 9228 and antioxidant 1076 in a mass ratio of 1:1), nucleating agent transparent talc, and chain extender ADR-4468.

[0049] Comparative Example 1-1: A foaming modifier for polybutylene terephthalate (PET) This comparative example provides a foaming modifier for polybutylene terephthalate (PBS), which is based on Example 1-1, except that the mass ratio of PBS, antioxidant (antioxidant 9228 and antioxidant 1076 in a mass ratio of 1:1), nucleating agent transparent talc, and chain extender ADR-4468 is replaced with 0.5:0.05:0.5:0.5.

[0050] Comparative Examples 1-2: A foaming modifier for polybutylene terephthalate (PET) This comparative example provides a foaming modifier for polybutylene terephthalate (PBS), which is based on Example 1-1, except that the mass ratio of PBS, antioxidant (antioxidant 9228 and antioxidant 1076 in a mass ratio of 1:1), nucleating agent transparent talc, and chain extender ADR-4468 is replaced with 2:0.05:0.5:1.

[0051] Comparative Examples 1-3: A foaming modifier for polybutylene terephthalate (PET) This comparative example provides a foaming modifier for polybutylene terephthalate, which is based on Example 1-1 but with the nucleating agent removed.

[0052] Comparative Examples 1-4: A foaming modifier for polybutylene terephthalate (PET) This comparative example provides a foaming modifier for polybutylene terephthalate, which is based on Example 1-1 but with the chain extender removed.

[0053] Comparative Examples 1-5: A foaming modifier for polybutylene terephthalate (PET) This comparative example provides a foaming modifier for polybutylene terephthalate, which is based on Example 1-1 but with the antioxidant removed.

[0054] Example 2-1: A foamed embryo This embodiment provides a foamed preform composed of polybutylene terephthalate in a mass ratio of 69.5:30.5 and the foaming modifier of Example 1-1.

[0055] The preparation method of the foamed preform is as follows: Polybutylene adipate terephthalate, polybutylene succinate, antioxidant, nucleating agent, and chain extender are first added to an oven and dried at 80°C for 4 hours. Then, they are added to a mixing tester and premixed at 100 rpm for 5 minutes to obtain mixture A. Mixture A is then added to a twin-screw micro extruder (SJZS-10A, Wuhan Ruiming Experimental Instrument Manufacturing Co., Ltd.) for melt blending (the twin-screw micro extruder parameters are: feed rate 150 g / min, from...). The temperatures of the nine zones from the feed inlet to the extruder head are set to 165 / 170 / 175 / 180 / 180 / 180 / 180 / 175 / 170℃, with a screw speed of 200 rpm. After underwater strip cooling, the material is fed into a pelletizer for granulation to obtain modified masterbatch. The modified masterbatch is first added to a dehumidifying drying oven and dried at 80℃ for 6 hours, then added to an injection molding machine and injection molded at 180℃ to obtain the foamed preform of the shoe material midsole (the length of the foamed preform, i.e., the shoe length before foaming, is 120 mm). This foamed preform is named Foamed Preform 1.

[0056] Comparative Example 2-1: A foamed embryo This comparative example provides a foamed preform, which, compared to Example 2-1, replaces the foaming modifier of Example 1-1 with the foaming modifier of Comparative Example 1-1. This foamed preform is named Foamed Preform 2.

[0057] Comparative Example 2-2: A foamed embryo This comparative example provides a foamed preform, which, compared to Example 2-1, replaces the foaming modifier of Example 1-1 with the foaming modifier of Comparative Example 1-2. This foamed preform is named Foamed Preform 3.

[0058] Comparative Examples 2-3: A foamed embryo This comparative example provides a foamed preform, which, compared to Example 2-1, replaces the foaming modifier of Example 1-1 with the foaming modifier of Comparative Examples 1-3. This foamed preform is named Foamed Preform 4.

[0059] Comparative Examples 2-4: A foamed embryo This comparative example provides a foamed preform, which, compared to Example 2-1, replaces the foaming modifier of Example 1-1 with the foaming modifier of Comparative Examples 1-4. This foamed preform is named Foamed Preform 5.

[0060] Comparative Examples 2-5: A foamed embryo This comparative example provides a foamed preform, which, compared to Example 2-1, replaces the foaming modifier of Example 1-1 with the foaming modifier of Comparative Examples 1-5. This foamed preform is named Foamed Preform 6.

[0061] Example 3-1: A foaming product This embodiment provides a foamed product, which is obtained by foaming the foamed preform 1 of Embodiment 2-1.

[0062] The preparation method of the foamed product is as follows: The foamed preform of Example 2-1 is placed in a supercritical foaming kettle (foaming kettle size is 500mm*350mm*600mm) at a temperature of 124℃ (foaming temperature), and supercritical carbon dioxide and supercritical nitrogen with a pressure ratio of 15:4 are introduced into the supercritical foaming kettle until the pressure inside the supercritical foaming kettle reaches 19MPa (foaming pressure); the foamed preform is placed in the supercritical foaming kettle at a pressure of 19MPa and a temperature of 124℃ for 120min, so that the supercritical carbon dioxide and supercritical nitrogen reach a dissolution equilibrium in the foamed preform; after reaching the dissolution equilibrium, the pressure inside the supercritical foaming kettle is released to the ambient pressure at an average depressurization rate of 5MPa / s to induce the nucleation and growth of cells, so that the foamed preform foams to obtain a foamed crude product; the foamed crude product is hot-pressed and shaped in a mold (first heated at 125℃ for 900s, then water-cooled for 900s) to obtain the foamed product. The foamed product is named Foamed Shoe Material Midsole 1.

[0063] Comparative Example 3-1: A foaming product This comparative example provides a foamed product obtained by foaming the foamed preform 2 of Comparative Example 2-1. The preparation method of the foamed product is the same as that of Example 3-1. This foamed product is named foamed shoe material midsole 2.

[0064] Comparative Example 3-2: A foaming product This comparative example provides a foamed product obtained by foaming the foamed preform 3 of Comparative Example 2-2. The preparation method of the foamed product is the same as that of Example 3-1. This foamed product is named foamed shoe material midsole 3.

[0065] Comparative Example 3-3: A foaming product This comparative example provides a foamed product obtained by foaming the foamed preform 4 of Comparative Examples 2-3. The preparation method of the foamed product is the same as that of Examples 3-1. This foamed product is named foamed shoe material midsole 4.

[0066] Comparative Examples 3-4: A foaming product This comparative example provides a foamed product obtained by foaming the foamed preform 5 of Comparative Examples 2-4. The preparation method of the foamed product is the same as that of Examples 3-1. This foamed product is named foamed shoe material midsole 5.

[0067] Comparative Examples 3-5: A foaming product This comparative example provides a foamed product obtained by foaming the foamed preform 6 of Comparative Examples 2-5. The preparation method of the foamed product is the same as that of Examples 3-1. This foamed product is named foamed shoe material midsole 6.

[0068] Comparative Examples 3-6: A foaming product This comparative example provides a foamed product, which is prepared by replacing the supercritical carbon dioxide and supercritical nitrogen with a pressure ratio of 4:15, based on Example 3-1. This foamed product is named Foamed Footwear Midsole 7.

[0069] Comparative Examples 3-7: A foaming product This comparative example provides a foamed product, which is prepared by replacing the supercritical carbon dioxide and supercritical nitrogen with a pressure ratio of 9:4 in Example 3-1, where the pressure ratio of 15:4 is replaced with that of 9:4. This foamed product is named Foamed Footwear Midsole 8.

[0070] Experimental Example 1: Performance Verification of Foamed Preform and Foamed Products This experimental example provides performance testing for different foamed preforms and shoe material midsoles. The experimental procedure is as follows: The melt index of foamed preforms 1 to 6 obtained in Example 1-1 and Comparative Examples 1-1 to 1-5 was tested using a high-speed iron melt index tester (test conditions: 190℃, 2.16kg). The viscosity of foamed preforms 1 to 6 obtained in Example 1-1 and Comparative Examples 1-1 to 1-5 was tested using a HAAK rotator. The heat distortion temperature of foamed preforms 1 to 6 obtained in Example 1-1 and Comparative Examples 1-1 to 1-5 was tested using a high-speed iron HV-3000-D3 tester. The results are shown in Table 1.

[0071] The apparent density of foamed shoe material midsole 1 to foamed shoe material midsole 8 obtained in Example 3-1 and Comparative Examples 3-1 to 3-7 was determined using the drainage method (test standard GB / T 6343-2009), and the foaming ratio was calculated (the calculation formula is: ratio = density before foaming / density after foaming). The results are shown in Table 2.

[0072] Using the ball rebound test standard GB / T 10652-2001, the rebound performance of the foamed shoe material midsole 1 to foamed shoe material midsole 8 obtained in Example 3-1 and Comparative Examples 3-1 to 3-7 was determined, and the results are shown in Table 2.

[0073] The hardness of the foamed shoe material midsole 1 to foamed shoe material midsole 8 obtained in Example 3-1 and Comparative Examples 3-1 to 3-6 was determined using a Shore C hardness tester with a hemispherical indenter. The results are shown in Table 2.

[0074] The delamination tear performance of foamed shoe material midsoles 1 to 8 obtained in Example 3-1 and Comparative Examples 3-1 to 3-7 was tested using a high-speed rail universal material testing machine (DIN 53507-B). The results are shown in Table 2.

[0075] After visually observing and photographing the foamed shoe material midsoles 1 to 8 obtained in Examples 3-1 and Comparative Examples 3-1 to 3-6, liquid nitrogen was used to quench and fracture the foamed shoe material midsoles 1 to 8 obtained in Examples 3-1 and Comparative Examples 3-1 to 3-6. The cell structure of the foamed shoe material midsoles 1 to 8 obtained in Examples 3-1 and Comparative Examples 3-1 to 3-7 was then observed using a scanning electron microscope (SEM). The photographic and scanning results are as follows: Figures 1-8 As shown.

[0076] As shown in Table 1, the melt index of the foamed preform obtained in Example 1-1 is 5.3 g / 10min and the viscosity is 10000 Pa·s. These two properties are well-matched, balancing injection molding processability and foaming properties. On the one hand, the suitable melt index ensures good melt flow during injection molding, facilitating rapid mold filling and reducing the molding cycle. On the other hand, the moderate viscosity provides sufficient melt strength, enabling stable cell wall growth during supercritical physical foaming and preventing gas escape and cell collapse. This balance provides a wide processing window for switching between injection molding and foaming processes, avoiding problems such as foam collapse due to excessively high melt index or injection molding difficulties due to excessively high viscosity. Simultaneously, its heat distortion temperature reaches 100.2℃, further providing a wide temperature window for hot pressing, ensuring dimensional stability of the product after cooling and setting, preventing warping and deformation. In summary, the synergy of these three factors enables the foamed preform obtained in Example 1-1 to have excellent process adaptability throughout the entire process of injection molding, foaming and hot pressing, which is far superior to the foamed preforms obtained in Comparative Examples 1-1 to 1-5.

[0077] As shown in Table 2, the midsole 1 of the shoe material obtained in Example 3-1 achieves a good overall balance between density, hardness, rebound, and delamination tear performance. Its density is as low as 0.06 g / cm³, giving the shoe material excellent lightweight properties; its hardness is 30 C, balancing a soft feel with sufficient structural support, avoiding the problems of decreased comfort due to excessive hardness or insufficient support due to insufficient hardness; its rebound rate reaches 75%, effectively reducing energy loss during exercise; and its delamination tear strength is 6.8 N / mm, indicating excellent interfacial bonding between the cell walls, effectively resisting delamination failure during repeated compression. In contrast, reducing the PBS dosage led to a density increase to 0.11 g / cm³ and a tear strength decrease to 5.2 N / mm; increasing the ADR chain extender dosage caused a sharp increase in density to 0.23 g / cm³, severely limiting the foaming ratio; removing the nucleating agent or antioxidant resulted in a rebound decrease to 70% and 66%, and a tear strength decrease to 4.8 N / mm and 4.2 N / mm, respectively, all showing significant deterioration in overall performance. The embodiment optimizes the component ratio, achieving a good synergistic match between lightweight, softness, dynamic rebound and structural durability in the shoe material midsole.

[0078] Depend on Figure 1 It can be seen that the foamed shoe material obtained in Example 3-1 has relatively small pore size in the sole, approximately 50-100 μm; Figure 2 It can be seen that, in the foamed shoe material midsole obtained in Comparative Example 3-1, due to the reduced amount of PBS added, the material's heat distortion temperature is significantly lowered, its hot-pressing and setting temperature window is narrow, and it is prone to material cracking; from Figure 3 It can be seen that, compared with the foamed shoe material midsole obtained in Example 3-2, due to the increased dosage of chain extender, the degree of molecular chain entanglement is deepened, and the material viscosity is increased. The foamed shoe material midsole obtained in Example 3-1 has smaller pores, but gas growth is limited, resulting in a limited foaming ratio. Figure 4 It can be seen that because the nucleating agent was removed, the material's crystallization ability weakened, and its ability to stabilize the foam cells deteriorated, resulting in larger foam cells and a higher open-cell ratio in the midsole of the foamed shoe material obtained in Comparative Example 3-3. Figure 5 It can be seen that the foamed shoe material midsole obtained in Comparative Examples 3-4 suffers from poor foaming due to insufficient melt strength, resulting in cell merging and rupture. Figure 6 It can be seen that the foamed shoe material midsole obtained in Comparative Examples 3-5, due to the lack of added antioxidants, has a yellowish color after foaming; Figure 7 It can be seen that, in the foamed shoe material midsole obtained in Comparative Examples 3-6, due to the adjustment of the ratio of the physical foaming agent (15:4 → 4:15), the foaming ratio was reduced by 60% compared with the foamed shoe material midsole obtained in Example 3-1; Figure 8It can be seen that the foamed shoe material midsole obtained in Comparative Examples 3-7, due to the adjustment of the ratio of physical foaming agent (15:4→9:4) and the reduction of gas pressure, has insufficient gas dissolved in the core of the foamed preform, making it difficult to foam and perhaps requiring a longer saturation time.

[0079] Table 1 Properties of different foamed preforms

[0080] Table 2 Performance of different shoe material midsoles

[0081] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A foaming modifier for polybutylene terephthalate, characterized in that, The foaming modifier comprises polybutylene succinate, antioxidant, nucleating agent and chain extender; the mass ratio of polybutylene succinate, antioxidant, nucleating agent and chain extender in the foaming modifier is 1~3:0.01~0.05:0.1~0.5:0.1~0.

5.

2. The foaming modifier as described in claim 1, characterized in that, The antioxidants include antioxidant 1010, antioxidant 1076 and / or antioxidant 9228; the nucleating agent includes talc; and the chain extender includes chain extender ADR-4468 and / or chain extender SG-20.

3. A foamed preform, characterized in that, The foamed preform comprises polybutylene adipate terephthalate and the foaming modifier as described in claim 1 or 2.

4. The foamed preform as described in claim 3, characterized in that, In the foamed preform, the mass ratio between polybutylene adipate and foaming modifier is 5.95~8.79:1.21~4.

05.

5. A method for preparing the foamed embryo as described in claim 3 or 4, characterized in that, The method includes: mixing polybutylene adipate terephthalate and a foaming modifier and then molding to obtain a foamed preform.

6. A foamed product, characterized in that, The foamed product is obtained by foaming the foamed preform as described in claim 3 or 4.

7. The foamed product as described in claim 6, characterized in that, The method for preparing the foamed product includes: placing a foamed preform in a foaming container at a foaming temperature, and introducing a physical foaming agent into the foaming container until the pressure inside the foaming container reaches the foaming pressure; continuously placing the foamed preform in the foaming container at the foaming pressure and foaming temperature until the physical foaming agent reaches a dissolution equilibrium in the foamed preform; releasing the pressure inside the foaming container to ambient pressure to induce the nucleation and growth of cells, causing the foamed preform to foam, thereby obtaining the foamed product.

8. The foamed product as described in claim 7, characterized in that, The physical foaming agent includes supercritical carbon dioxide fluid and / or supercritical nitrogen fluid.

9. A method for preparing the foamed product according to any one of claims 6 to 8, characterized in that, The method includes: foaming the foamed preform as described in claim 3 or 4 to obtain a foamed product.

10. The use of the foaming modifier according to claim 1 or 2 or the foamed preform according to claim 3 or 4 in the preparation of foamed products.

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