High-resilience light-weight thermoplastic elastomer foamed synthetic leather for automotive trim and forming process of high-resilience light-weight thermoplastic elastomer foamed synthetic leather

Abstract

The invention discloses high-resilience light-weight thermoplastic elastomer foamed synthetic leather for automotive interiors and a forming process of the high-resilience light-weight thermoplastic elastomer foamed synthetic leather, and relates to the field of high-molecular compounds. The functional additive comprises the following components in percentage by total mass of the base material: 1-3% of a physical foaming agent; the adding amount of a nucleating agent is 1-2%; the addition amount of a silane coupling agent is 0.5-1%; the addition amount of a peroxide cross-linking agent is 0.2-0.5%; the synthetic leather has a gradient foaming structure and comprises a compact surface layer and a middle high-elastic layer, according to the synthetic leather with the gradient foaming structure, VOC migration is limited by utilizing a closed-cell structure through a physical barrier effect, a dynamic cross-linked network stabilizes molecular chain movement through chemical bonds, small molecule release is reduced, integrated forming is achieved, light weight and high resilience are guaranteed, and meanwhile through closed-cell barrier, dynamic cross-linking stability and a plasticizer-free system, the synthetic leather has a good foaming effect. VOC release is remarkably reduced, and the high-standard requirements of automobile interiors are met.

Description

Technical Field

[0001] This invention relates to the field of polymer compound technology, and in particular to a high-resilience, lightweight thermoplastic elastomer foamed synthetic leather for automotive interiors and its molding process. Background Technology

[0002] In the automotive industry, the choice of interior materials directly affects the overall performance, comfort, and environmental standards of a vehicle. Traditional automotive interior synthetic leather mainly uses resin-based materials such as polyvinyl chloride (PVC), polyurethane (PU), or thermoplastic polyurethane (TPU). While these materials possess certain processing properties, they also have inherent drawbacks.

[0003] First, traditional resin-based materials generally suffer from high density, typically exceeding 1.2 g / cm³. This not only increases the overall weight of the vehicle and impacts fuel economy but also contradicts the current trend of lightweighting in the automotive industry. Second, these materials have poor resilience, with a rebound rate usually below 70%, leading to defects such as deformation and stiffness after prolonged use. More importantly, traditional synthetic leather uses large amounts of volatile organic compounds (VOCs) such as plasticizers, which release harmful gases at high temperatures, polluting the vehicle interior and posing a potential threat to human health.

[0004] In the existing technology, in order to meet the requirements of lightweight and high resilience, traditional synthetic leather mostly adopts chemical foaming technology. By adding azo or bicarbonate chemical foaming agents, the gas is decomposed at high temperature to form a cell structure. However, the chemical foaming process is complex, has high requirements for process condition control, and it is difficult to guarantee the uniformity of the cells. At the same time, the residues and by-products of chemical foaming agents will further increase the VOC release, exacerbating environmental hazards.

[0005] Therefore, it is necessary to improve upon the shortcomings of existing technologies in order to solve the above problems. Summary of the Invention

[0006] This invention overcomes the shortcomings of the prior art and provides a high-resilience, lightweight thermoplastic elastomer foamed synthetic leather for automotive interiors and its molding process. Through the synergy of thermoplastic elastomer substrate system and gradient foaming process, it achieves a comprehensive improvement in lightweight, high resilience and environmental protection by eliminating resin-based materials and chemical foaming agents.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a high-resilience, lightweight thermoplastic elastomer foamed synthetic leather for automotive interiors, comprising the following components:

[0008] Matrix material: Composed of a thermoplastic elastomer composition and fillers, comprising, by weight parts:

[0009] 40-60 parts of styrene block copolymers;

[0010] 20-30 parts of polyolefin elastomer;

[0011] 10-15 parts of polar ethylene copolymer;

[0012] 5-15 parts of hollow inorganic microspheres;

[0013] Functional additives: based on the total mass of the total substrate, including:

[0014] Physical foaming agent injection rate: 1-3%;

[0015] Nucleating agent addition amount: 1-2%;

[0016] Silane coupling agent addition amount: 0.5-1%;

[0017] Peroxide crosslinking agent addition amount: 0.2-0.5%;

[0018] The synthetic leather has a gradient foaming structure, including a dense surface layer and an intermediate high-elastic layer; the bottom of the intermediate high-elastic layer is a composite bottom support layer, the material of the bottom support layer is polyester nonwoven fabric, the cell diameter of the dense surface layer is 10-50 μm, and the cell diameter of the intermediate high-elastic layer is 100-160 μm.

[0019] In a preferred embodiment of the present invention, the styrene block copolymer is one of hydrogenated styrene-butadiene block copolymer or styrene-ethylene-propylene-styrene block copolymer; the polyolefin elastomer is one of ethylene-octene copolymer or olefin block copolymer; and the polar ethylene copolymer is one of ethylene-vinyl acetate copolymer or ethylene-vinyl alcohol copolymer.

[0020] In a preferred embodiment of the present invention, the hollow inorganic microspheres are either glass microspheres or ceramic microspheres, with a particle size of 20-50 μm and a wall thickness of 1-3 μm.

[0021] In a preferred embodiment of the present invention, the physical foaming agent is supercritical CO2; the nucleating agent is one of nano-silica or talc powder with a particle size of 10-50 nm; the silane coupling agent is one of γ-aminopropyltriethoxysilane or N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane; and the peroxide crosslinking agent is dicumyl peroxide.

[0022] In a preferred embodiment of the present invention, the thickness of the dense surface layer is 0.1-0.2 mm, the thickness of the intermediate high-elasticity layer is 1.5-2 mm, and the basis weight of the polyester nonwoven fabric is 80-120 g / m². 2 .

[0023] This invention provides a molding process for high-resilience, lightweight thermoplastic elastomer foamed synthetic leather for automotive interiors, comprising the following steps:

[0024] S1. Styrene block copolymer, polyolefin elastomer, polar ethylene copolymer, hollow inorganic microspheres, nucleating agent and silane coupling agent are premixed and then melt-blended in a twin-screw extruder.

[0025] S2. Inject a physical foaming agent at a certain pressure in the middle section of the extruder;

[0026] S3. Add peroxide crosslinking agent to the end of the extruder, hold for 30-60 seconds, extrude through the slit die and instantly depressurize to foam, forming a gradient foam structure;

[0027] S4. The foamed structure is combined with polyester nonwoven fabric by hot press roller to obtain foamed synthetic leather.

[0028] In a preferred embodiment of the present invention, in step S1, the extruder temperature is 180-200 ℃ and the screw speed is 100-200 rpm.

[0029] In a preferred embodiment of the present invention, the pressure in step S2 is 15-20 MPa.

[0030] In a preferred embodiment of the present invention, in step S3, the gap between the lip of the slit mold is 1.5-2 mm; the dense surface layer of the gradient foaming structure is formed by rapid cooling through the mold outlet, the cooling medium being water or air, and the cooling rate being 50-70 ℃ / s.

[0031] In a preferred embodiment of the present invention, in step S4, the composite temperature is 100-120 °C and the pressure is 0.5-1.5 MPa.

[0032] This invention addresses the shortcomings of the prior art and has the following beneficial effects:

[0033] (1) This invention provides a high-resilience lightweight thermoplastic elastomer foamed synthetic leather for automotive interiors and its molding process. Through the synergy of thermoplastic elastomer matrix material and functional additives, combined with a one-step continuous extrusion dynamic crosslinking foaming process, during the extrusion process, the physical foaming agent is uniformly dissolved in the melt under high pressure. When the melt is extruded through the slit die, the surface layer is rapidly cooled due to contact with the low-temperature die lip, and the melt viscosity increases sharply, inhibiting cell growth and forming a dense and hard surface layer. During the pressure release process, the supercritical CO2 in the middle layer expands rapidly, and the dynamic crosslinking network formed by the crosslinking agent restricts excessive cell growth, forming a uniform closed-cell structure, which imparts high resilience performance and forms a synthetic leather with a gradient foaming structure. Thus, the closed-cell structure restricts VOC migration through physical barrier effect, while the dynamic crosslinking network stabilizes molecular chain movement through chemical bonds, further reducing the release of small molecules. The integrated molding does not require a secondary bonding process. While ensuring lightweight and high resilience, the VOC release is significantly reduced through closed-cell barrier, dynamic crosslinking stability and plasticizer-free system, meeting the high standard requirements of automotive interiors.

[0034] (2) In this invention, a microphase separation structure is formed by using the styrene hard segments of styrene block copolymers and the flexible segments of polyolefin elastomers. The former provides physical crosslinking points for elastic recovery, while the latter dissipates energy through segment slippage. The polar vinyl acetate segments of polar ethylene copolymers reduce melt viscosity, making the filler uniformly dispersed and reducing stress concentration. The cavity structure of hollow inorganic microspheres reduces density through physical occupancy effect. At the same time, its rigid shell dissipates energy through micro-deformation when under stress, forming a stress transmission path of "soft matrix-hard filler", effectively preventing crack propagation and achieving synergistic effect of lightweighting and tear resistance.

[0035] (3) In this invention, the peroxide crosslinking agent introduced at the end of the extruder decomposes to generate active free radicals during dynamic vulcanization. These free radicals preferentially attack the butadiene double bonds of the styrene block copolymer to form a controllable crosslinking network. This network maintains the thermoplastic processing characteristics of TPE and enhances the restoring force between molecular chains through chemical bonds. On the one hand, it constrains the excessive slippage of molecular chains, stabilizes cell growth during foaming, and prevents cell collapse or merging. On the other hand, the crosslinking points and the filler surface modified by the silane coupling agent form a ternary synergistic interface of "filler-matrix-crosslinking point" through physical entanglement or chemical bonding, thereby forming a stable and highly elastic cell skeleton structure. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a schematic cross-sectional view of a thermoplastic elastomer foamed synthetic leather according to a preferred embodiment of the present invention;

[0038] Figure 2 This is a flow chart of the molding process of thermoplastic elastomer foamed synthetic leather according to a preferred embodiment of the present invention;

[0039] In the diagram: 1. Dense surface layer; 2. Intermediate high-elasticity layer; 3. Bottom support layer. Detailed Implementation

[0040] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein. Therefore, the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0042] It should be noted that the raw materials, equipment and reagents used in this invention can all be purchased from the market or obtained through existing preparation methods.

[0043] like Figure 1 As shown, a high-resilience, lightweight thermoplastic elastomer foamed synthetic leather for automotive interiors comprises the following components:

[0044] Matrix material: Composed of a thermoplastic elastomer composition and fillers, comprising, by weight parts:

[0045] 40-60 parts of styrene block copolymers;

[0046] 20-30 parts of polyolefin elastomer;

[0047] 10-15 parts of polar ethylene copolymer;

[0048] 5-15 parts of hollow inorganic microspheres;

[0049] Functional additives: based on total substrate mass, including:

[0050] Physical foaming agent injection rate: 1-3%;

[0051] Nucleating agent addition amount: 1-2%;

[0052] Silane coupling agent addition amount: 0.5-1%;

[0053] Peroxide crosslinking agent addition amount: 0.2-0.5%;

[0054] The synthetic leather has a gradient foaming structure, including a dense surface layer 1 and a middle high-elastic layer 2; the bottom of the middle high-elastic layer 2 is composite with a bottom support layer 3, the bottom support layer 3 is made of polyester non-woven fabric, the cell diameter of the dense surface layer 1 is 10-50 μm, and the cell diameter of the middle high-elastic layer 2 is 100-160 μm.

[0055] In some specific embodiments, the styrene block copolymer is one of hydrogenated styrene-butadiene block copolymer (SEBS) or styrene-ethylene-propylene-styrene block copolymer (SEPS); the polyolefin elastomer is one of ethylene-octene copolymer (POE) or olefin block copolymer (OBC); and the polar ethylene copolymer is one of ethylene-vinyl acetate copolymer (EVA) or ethylene-vinyl alcohol copolymer (EVOH).

[0056] In some specific embodiments, the hollow inorganic microspheres are either glass microspheres or ceramic microspheres, with a particle size of 20-50 μm and a wall thickness of 1-3 μm.

[0057] In some specific embodiments, the physical foaming agent is supercritical CO2; the nucleating agent is one of nano-silica (SiO2) or talc powder with a particle size of 10-50 nm; the silane coupling agent is one of γ-aminopropyltriethoxysilane (KH550) or N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane (KH792); and the peroxide crosslinking agent is dicumyl peroxide (DCP).

[0058] In some specific embodiments, the thickness of the dense surface layer 1 is 0.1-0.2 mm, the thickness of the intermediate high-elastic layer 2 is 1.5-2 mm, and the basis weight of the polyester nonwoven fabric is 80-120 g / m². 2 .

[0059] This invention provides a molding process for high-resilience, lightweight thermoplastic elastomer foamed synthetic leather for automotive interiors, comprising the following steps:

[0060] S1. Styrene block copolymer, polyolefin elastomer, polar ethylene copolymer, hollow inorganic microspheres, nucleating agent and silane coupling agent are premixed and then melt-blended in a twin-screw extruder.

[0061] S2. Inject a physical foaming agent at a certain pressure in the middle section of the extruder;

[0062] S3. Add peroxide crosslinking agent to the end of the extruder, hold for 30-60 seconds, extrude through the slit die and instantly depressurize to foam, forming a gradient foam structure;

[0063] S4. The foamed structure is combined with polyester nonwoven fabric by hot press roller to obtain foamed synthetic leather.

[0064] In some specific embodiments, in step S1, the extruder temperature is 180-200 ℃ and the screw speed is 100-200 rpm.

[0065] In some specific implementations, the pressure in step S2 is 15-20 MPa.

[0066] In some specific embodiments, in step S3, the gap between the lip of the slit mold is 1.5-2 mm; the dense surface layer 1 of the gradient foam structure is formed by rapid cooling through the mold outlet, the cooling medium being water or air, and the cooling rate being 50-70℃ / s.

[0067] In some specific implementations, in step S4, the composite temperature is 100-120 °C and the pressure is 0.5-1.5 MPa.

[0068] To further simplify and make the objectives and effects of the present invention easier to understand, the present invention will be further described in conjunction with embodiments and comparative examples.

[0069] It should be noted that the raw materials used in the examples and comparative examples are described below:

[0070] Hydrogenated styrene-butadiene block copolymer: specific gravity 0.910 g / cm³ 3 Grade G1645M, purchased from Shanghai Rongguangsen Plastics; styrene-ethylene-propylene-styrene block copolymer: specific gravity 0.920 g / cm³ 3 Grade G1701MU, purchased from Shanghai Rongguangsen Plastics; Ethylene-octene copolymer: density 0.878 g / cm³ 3 The following materials were purchased from Suzhou Yican Plastics: Olefin block copolymer (3980FL, purchased from Shanghai Rongguangsen Plastics); UE612-04 (Original grade, purchased from Suzhou Yican Plastics); Ethylene-vinyl alcohol copolymer (7010, purchased from Suzhou Yican Plastics); and glass microspheres (35 μm particle size, 2 μm wall thickness, 0.125 g / cm³). 3 The following materials were purchased from Beijing Lijin Tiancheng (CAS No. 65997-17-3); ceramic microspheres (46 μm particle size, 3 μm wall thickness) were purchased from Hebei Hengguang Mineral Resources; nano-silica (20 nm particle size, grade JL-SP20) was purchased from Hangzhou Jiuli Biotechnology; and talc (50 nm particle size, 2.86 g / cm³) was purchased from Hebei Hengguang Mineral Resources. 3Purchased from Hebei Leijiang New Materials; γ-aminopropyltriethoxysilane: CAS No. 919-30-2, purchased from Wuhan Huaxiang Kejie Biotechnology; N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane: CAS No. 1760-24-3, purchased from Wuhan Huaxiang Kejie Biotechnology; dicumyl peroxide: grade BIBP-96, purchased from Dongguan Weijie New Materials; polyester nonwoven fabric, basis weight 100 g / m². 2 Thickness 0.3 mm, purchased from Zhengzhou Rongtong Engineering Materials.

[0071] The raw materials and raw material ratios of the foamed synthetic leather matrix material and functional additives in Examples 1-7 are different; the matrix material is specifically shown in Table 1, with the raw material usage measured in parts by mass; the functional additives are specifically shown in Table 2, with the raw material usage measured in total matrix mass.

[0072] Table 1: Raw materials and proportions for the preparation of foamed synthetic leather matrix materials in Examples 1-7

[0073]

[0074] Table 2: Raw materials and proportions for the preparation of the foamed synthetic leather functional additives in Examples 1-7

[0075]

[0076] Example 1

[0077] A molding process for high-resilience, lightweight thermoplastic elastomer foamed synthetic leather for automotive interiors includes the following steps:

[0078] S1. After premixing SEBS, POE, EVA, glass microspheres, SiO2 and KH550, add them to a twin-screw extruder and melt-blend them at an extruder temperature of 190°C and a screw speed of 140 rpm.

[0079] S2. In the middle section of the extruder, supercritical CO2 is injected at a pressure of 18 MPa;

[0080] S3. Add DCP to the end of the extruder, hold for 48 s, extrude through a slit die with a die lip gap of 1.8 mm and instantly depressurize and foam. The cooling medium at the die outlet is water with a cooling rate of 55 ℃ / s, forming a gradient foaming structure.

[0081] S4. The foamed structure is combined with polyester nonwoven fabric by hot press rollers at a pressure of 110 ℃ and 1 MPa to obtain foamed synthetic leather.

[0082] The dense surface layer 1 of the gradient foam structure has a thickness of 0.2 mm, and the intermediate high-elastic layer 2 has a thickness of 1.7 mm.

[0083] Example 2

[0084] This embodiment is basically the same as embodiment 1, except that the raw material ratio is different, as shown in Table 1 and Table 2; the specific steps of S2 are as follows: supercritical CO2 is injected into the middle section of the extruder at a pressure of 15 MPa.

[0085] Example 3

[0086] This embodiment is basically the same as embodiment 1, except that the raw materials and their proportions are different, as shown in Table 1 and Table 2; the specific steps of S2 are as follows: supercritical CO2 is injected into the middle section of the extruder at a pressure of 20 MPa.

[0087] Example 4

[0088] This embodiment is basically the same as embodiment 1, except that the raw materials and their proportions are different, as shown in Tables 1 and 2. The specific steps of S3 are as follows: DCP is added to the end of the extruder, held for 30 seconds, and extruded through a slit die with a die lip gap of 1.8 mm and instantly depressurized to form foam. The cooling medium at the die outlet is water, with a cooling rate of 55 ℃ / s, forming a gradient foam structure.

[0089] Example 5

[0090] This embodiment is basically the same as embodiment 1, except that the raw materials and their proportions are different, as shown in Tables 1 and 2. The specific steps of S3 are as follows: DCP is added to the end of the extruder, held for 60 seconds, and extruded through a slit die with a die lip gap of 1.8 mm and instantly depressurized to form foam. The cooling medium at the die outlet is water, with a cooling rate of 55 ℃ / s, forming a gradient foam structure.

[0091] Example 6

[0092] This embodiment is basically the same as embodiment 1, except that the raw materials and their proportions are different, as shown in Table 1 and Table 2.

[0093] Example 7

[0094] This embodiment is basically the same as embodiment 1, except that the raw materials and their proportions are different, as shown in Table 1 and Table 2.

[0095] Comparative Example 1

[0096] Commercially available: PU synthetic leather, 2 mm thick, purchased from Yongdeyu Leather in Xiamen.

[0097] Comparative Example 2

[0098] This comparative example is basically the same as Example 1, except that the physical foaming agent injection pressure is different. The specific step of S2 is: supercritical CO2 is injected at a pressure of 14 MPa in the middle section of the extruder.

[0099] Comparative Example 3

[0100] This comparative example is basically the same as Example 1, except that the injection pressure of the physical foaming agent is different. The specific step of S2 is: supercritical CO2 is injected at a pressure of 21 MPa in the middle section of the extruder.

[0101] Comparative Example 4

[0102] This comparative example is basically the same as Example 1, except that no peroxide crosslinking agent was added. The specific steps of S3 are as follows: extrusion and instantaneous pressure release foaming are performed through a slit die with a die lip gap of 1.8 mm. The cooling medium at the die outlet is water, and the cooling rate is 55 ℃ / s, forming a gradient foaming structure.

[0103] Comparative Example 5

[0104] This comparative example is basically the same as Example 1, except that the amount of peroxide crosslinking agent used is different. Specifically, the amount of DCP added is 0.1% of the total substrate mass.

[0105] Comparative Example 6

[0106] This comparative example is basically the same as Example 1, except that the amount of peroxide crosslinking agent used is different. Specifically, the amount of DCP added is 0.6% of the total substrate mass.

[0107] Comparative Example 7

[0108] This comparative example is basically the same as Example 1, except that the crosslinking residence time is different. The specific steps of S3 are as follows: DCP is added at the end of the extruder, and the residence time is 27 s. The extrusion is carried out through a slit die with a die lip gap of 1.8 mm and the pressure is released and foamed instantly. The cooling medium at the die outlet is water, and the cooling rate is 55 ℃ / s, forming a gradient foam structure.

[0109] Comparative Example 8

[0110] This comparative example is basically the same as Example 1, except that the crosslinking residence time is different. The specific steps of S3 are as follows: DCP is added at the end of the extruder, and the residence time is 65 s. The extrusion is carried out through a slit die with a die lip gap of 1.8 mm and the pressure is released and foamed instantly. The cooling medium at the die outlet is water, and the cooling rate is 55 ℃ / s, forming a gradient foam structure.

[0111] Comparative Example 9

[0112] This comparative example is basically the same as Example 1, except that the amount of styrene block copolymer used is different. Specifically, the amount of SEBS used is 38 parts by mass.

[0113] Comparative Example 10

[0114] This comparative example is basically the same as Example 1, except that the amount of styrene block copolymer used is different. Specifically, the amount of SEBS used is 64 parts by mass.

[0115] Comparative Example 11

[0116] This comparative example is basically the same as Example 1, except that no filler is added to the matrix material. The specific steps of S1 are as follows: SEBS, POE, EVA, SiO2 and KH550 are premixed and then added to a twin-screw extruder and melt-blended at an extruder temperature of 190 °C and a screw speed of 140 rpm.

[0117] Comparative Example 12

[0118] This comparative example is basically the same as Example 1, except that the amount of filler in the matrix material is different. Specifically, the amount of glass microspheres is 4 parts by mass.

[0119] Comparative Example 13

[0120] This comparative example is basically the same as Example 1, except that the amount of filler in the matrix material is different. Specifically, the amount of glass microspheres is 17 parts by mass.

[0121] Comparative Example 14

[0122] This comparative example is basically the same as Example 1, except that no silane coupling agent was added. The specific steps of S1 are as follows: SEBS, POE, EVA, glass microspheres and SiO2 are premixed and then added to a twin-screw extruder and melt-blended at an extruder temperature of 190 °C and a screw speed of 140 rpm.

[0123] Cell detection: The foamed synthetic leather obtained from Examples 1-7 and Comparative Examples 2-14 was cut perpendicular to the surface direction. At least 50 cells were measured in the sample layer (dense surface layer 1 and intermediate high elastic layer 2) of each sample. The maximum diameter of each cell was measured and the average diameter was calculated. The results are shown in Table 3.

[0124] Performance testing: The foamed synthetic leather obtained from Examples 1-7 and Comparative Examples 2-14, as well as the PU synthetic leather from Comparative Example 1, were made into 100 mm × 100 mm samples. The performance tests of resilience, lightweight, environmental protection and aging resistance were carried out in sequence. The results are shown in Table 4.

[0125] Rebound test: Place the sample in a standard test environment (23±2℃, humidity 50±5%), use a rebound hammer to vertically impact the sample surface, and measure the rebound rate = (rebound height / initial height) × 100%. Repeat three times and take the average value.

[0126] Lightweighting test: Measure the mass and volume of the sample and calculate the apparent density.

[0127] Environmental testing: The sample was placed in a sealed environmental chamber (temperature 65℃, humidity 5%), and the gas inside the chamber was collected after 24 hours. The total volatile matter content was quantitatively analyzed by gas chromatography-mass spectrometry (GC-MS).

[0128] Aging resistance test: After the sample is aged at 85℃ and 85%RH for 1500 hours, environmental protection and tensile strength tests are carried out respectively. The environmental protection test adopts the same test method as above, and the tensile strength is determined according to GB / T 1040.1-2018 "Determination of tensile properties of plastics". The tensile strength retention rate is calculated as (strength after aging / initial strength) × 100%.

[0129] Table 3: Average pore diameter of sample layers from Examples 1-7 and Comparative Examples 2-14

[0130]

[0131] Table 4: Performance test results of samples from Examples 1-7 and Comparative Examples 1-14

[0132]

[0133] As shown in Tables 3 and 4:

[0134] A comparison of Examples 1-7 reveals that this invention utilizes a microphase separation structure (synergistic effect of SEBS hard segments and POE soft segments), a dynamic crosslinking network (controlled crosslinking initiated by DCP), and a gradient foaming process (supercritical CO2 pressure regulation) in a thermoplastic elastomer substrate to construct a closed-cell structure consisting of a dense surface layer 1 (10-50 μm) and an intermediate high-elasticity layer 2 (100-150 μm). The dense surface layer 1 inhibits cell growth through rapid cooling, while the intermediate layer restricts cell expansion through a crosslinking network. Simultaneously, a silane coupling agent enhances the filler-matrix interface bonding, forming a stable "soft matrix-hard filler" stress transmission path. This achieves a balance between elastic recovery force and energy dissipation. The closed-cell structure physically blocks VOC migration, dynamic crosslinking reduces small molecule release, and the plasticizer-free system further reduces pollution risk. The resulting synthetic leather exhibits excellent environmental performance while maintaining lightweight and high resilience, and also demonstrates outstanding aging resistance and tear resistance.

[0135] A comparison of Examples 1-7 with Comparative Example 1 reveals that traditional PU synthetic leather, with its resin-based material lacking the microphase separation structure of thermoplastic elastomers, has molecular chains connected only by physical entanglement or hydrogen bonds, failing to form a dynamic cross-linked network. This results in a significantly reduced resilience and a density as high as 1.32 g / cm³. 3 Furthermore, the VOC release amount far exceeds that of the embodiments of the present invention.

[0136] A comparison of Examples 1-7 with Comparative Examples 2-3 reveals that: Comparative Example 2, with a foaming pressure of 14 MPa, resulted in insufficient supercritical CO2 solubility, a reduction in nucleation points, and excessively small and sparsely distributed pore diameters in the dense surface layer 1 and the intermediate high-elasticity layer 2, leading to a decrease in resilience to 72.3%; Comparative Example 3, with a pressure of 21 MPa, experienced excessively rapid surface cooling, resulting in excessively large pore diameters (60 μm) in the dense layer and excessive expansion of the intermediate layer pores (180 μm), leading to a decrease in closed-cell ratio and a significant increase in VOC emissions. This invention optimizes the pressure range to balance nucleation point density and pore growth, ensuring the stability of the gradient structure.

[0137] A comparison of Examples 1-7 with Comparative Example 4 reveals that: Comparative Example 4, lacking DCP, suffers from a missing dynamic cross-linking network, with SEBS molecular chains relying solely on physical cross-linking. This results in insufficient cell wall strength, excessively large and collapsed intermediate layer cell diameter (220 μm), a sharp drop in resilience to 65.24%, and a significant decrease in tensile strength retention (70.19%). This invention, through a controllable cross-linking network induced by DCP, restricts cell expansion and enhances elastic recovery, while simultaneously reducing the release of small molecules caused by molecular chain slippage.

[0138] A comparison of Examples 1-7 with Comparative Examples 5-6 reveals that: in Comparative Example 5, the DCP dosage (0.1%) was insufficient, resulting in low crosslinking density, a larger intermediate layer cell diameter (170 μm), a decreased closed-cell rate, and increased VOC emissions; in Comparative Example 6, the DCP dosage was excessive (0.6%), leading to over-crosslinking and excessively rigid cell walls (intermediate layer cell diameter 95 μm), increased material brittleness, and a decrease in resilience to 75.68%. This invention precisely controls the crosslinking density by adjusting the DCP dosage, balancing cell size and elasticity.

[0139] A comparison of Examples 1-7 and Comparative Examples 7-8 reveals that: Comparative Example 7, with a residence time of 27 s, exhibited insufficient cross-linking reaction, resulting in uneven distribution of intermediate layer pores (195 μm) due to excessive gas diffusion, leading to a significant increase in VOC release; Comparative Example 8, with a residence time of 65 s, resulted in excessive cross-linking, leading to excessively thick pore walls (130 μm), which enhanced material rigidity but reduced resilience to 87.43%. This invention optimizes residence time to ensure a match between the dynamic cross-linking network and the foaming rate.

[0140] A comparison of Examples 1-7 with Comparative Examples 9-10 reveals that: in Comparative Example 9, the amount of SEBS was insufficient, resulting in a lower proportion of styrene hard segments, fewer physical crosslinking points, insufficient cell wall strength (70 μm in the dense layer), and excessively large intermediate layer pores (190 μm); in Comparative Example 10, the amount of SEBS was excessive, leading to excessive material rigidity, excessively small intermediate layer pores (110 μm), and limited resilience (78.21%). This invention balances elasticity and strength by controlling the amount of SEBS used to regulate the microphase separation structure.

[0141] A comparison of Examples 1-7 with Comparative Example 11 reveals that: Comparative Example 11, without added filler, lacks a "soft matrix - hard filler" stress transfer path, resulting in severe cell collapse (90 μm dense layer, 250 μm intermediate layer) and an increased density to 1.16 g / cm³. 3 .

[0142] A comparison of Examples 1-7 with Comparative Examples 12-13 reveals that: Comparative Example 12 had too low a filler content, resulting in insufficient rigidity enhancement and excessively large intermediate layer pores (200 μm); Comparative Example 13 had excessive filler content, leading to interfacial bonding failure, reduced closed-cell rate, high VOC release (76 μg / g), and insufficient mechanical properties (tensile retention rate of 85.14%). This invention optimizes interfacial bonding and physical occupancy effects through filler content optimization.

[0143] A comparison of Examples 1-7 with Comparative Example 14 reveals that: Comparative Example 14, without the addition of a silane coupling agent, exhibits weak interfacial bonding between the filler and the matrix, stress concentration on the cell walls (95 μm for the dense layer and 240 μm for the intermediate layer), reduced closed-cell ratio, and a significantly increased VOC emission (94 μg / g). This invention modifies the filler surface with a silane coupling agent to form a chemically bonded interface, thereby enhancing cell stability.

[0144] The above description is based on the preferred embodiments of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered exemplary and non-limiting in all respects. The scope of the invention is defined by the appended claims rather than the foregoing description, and all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0145] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A high-resilience, lightweight thermoplastic elastomer foamed synthetic leather for automotive interiors, characterized in that, It includes the following components: Matrix material: Composed of a thermoplastic elastomer composition and fillers, comprising, by weight parts: 40-60 parts of styrene block copolymers; 20-30 parts of polyolefin elastomer; 10-15 parts of polar ethylene copolymer; 5-15 parts of hollow inorganic microspheres; Functional additives: based on total substrate mass, including: Physical foaming agent injection rate: 1-3%; Nucleating agent addition amount: 1-2%; Silane coupling agent addition amount: 0.5-1%; Peroxide crosslinking agent addition amount: 0.2-0.5%; The synthetic leather has a gradient foaming structure, including a dense surface layer and a middle high-elastic layer; the bottom of the middle high-elastic layer is a composite bottom support layer, the material of the bottom support layer is polyester nonwoven fabric, the cell diameter of the dense surface layer is 10-50 μm, and the cell diameter of the middle high-elastic layer is 100-160 μm.

2. The high-resilience, lightweight thermoplastic elastomer foamed synthetic leather for automotive interiors according to claim 1, characterized in that: The styrene block copolymer is one of hydrogenated styrene-butadiene block copolymer or styrene-ethylene-propylene-styrene block copolymer; the polyolefin elastomer is one of ethylene-octene copolymer or olefin block copolymer; the polar ethylene copolymer is one of ethylene-vinyl acetate copolymer or ethylene-vinyl alcohol copolymer.

3. The high-resilience, lightweight thermoplastic elastomer foamed synthetic leather for automotive interiors according to claim 1, characterized in that: The hollow inorganic microspheres are either glass microspheres or ceramic microspheres, with a particle size of 20-50 μm and a wall thickness of 1-3 μm.

4. The high-resilience, lightweight thermoplastic elastomer foamed synthetic leather for automotive interiors according to claim 1, characterized in that: The physical foaming agent is supercritical CO2; the nucleating agent is either nano-silica or talc powder with a particle size of 10-50 nm; the silane coupling agent is either γ-aminopropyltriethoxysilane or N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane; and the peroxide crosslinking agent is dicumyl peroxide.

5. The high-resilience, lightweight thermoplastic elastomer foamed synthetic leather for automotive interiors according to claim 1, characterized in that: The thickness of the dense surface layer is 0.1-0.2 mm, the thickness of the intermediate high-elastic layer is 1.5-2 mm, and the basis weight of the polyester nonwoven fabric is 80-120 g / m². 2 .

6. A molding process for a high-resilience, lightweight thermoplastic elastomer foamed synthetic leather for automotive interiors according to any one of claims 1-5, characterized in that, Includes the following steps: S1. Styrene block copolymer, polyolefin elastomer, polar ethylene copolymer, hollow inorganic microspheres, nucleating agent and silane coupling agent are premixed and then melt-blended in a twin-screw extruder. S2. Inject a physical foaming agent at a certain pressure in the middle section of the extruder; S3. Add peroxide crosslinking agent to the end of the extruder, hold for 30-60 seconds, extrude through the slit die and instantly depressurize to foam, forming a gradient foam structure; S4. The foamed structure is combined with polyester nonwoven fabric by hot press roller to obtain foamed synthetic leather.

7. The molding process for a high-resilience, lightweight thermoplastic elastomer foamed synthetic leather for automotive interiors according to claim 6, characterized in that: In step S1, the extruder temperature is 180-200 ℃ and the screw speed is 100-200 rpm.

8. The molding process for a high-resilience, lightweight thermoplastic elastomer foamed synthetic leather for automotive interiors according to claim 6, characterized in that: In step S2, the pressure is 15-20 MPa.

9. The molding process for a high-resilience, lightweight thermoplastic elastomer foamed synthetic leather for automotive interiors according to claim 6, characterized in that: In step S3, the gap between the lip of the slit mold head is 1.5-2 mm; the dense surface layer of the gradient foaming structure is formed by rapid cooling through the mold head outlet, with water or air as the cooling medium and a cooling rate of 50-70℃ / s.

10. The molding process for a high-resilience, lightweight thermoplastic elastomer foamed synthetic leather for automotive interiors according to claim 6, characterized in that: In step S4, the composite temperature is 100-120 ℃ and the pressure is 0.5-1.5 MPa.

Images