Environment-friendly automotive interior synthetic leather based on polyester degradable plastic and laminating process thereof

Abstract

The application discloses an environment-friendly automotive interior synthetic leather based on polyester degradable plastic and a laminating process thereof, and belongs to the technical field of polyester-based plastics. The polyester plastic is prepared by melt reactive extrusion grafting of modified polyester obtained by polycondensation of carbon-carbon double bond-containing diols and the like, phosphorus-containing lignin and anti-aging agents, and is spun into a non-woven fabric base cloth. The synthetic leather is composed of the base cloth and a water-based polyurethane surface layer containing a blocked isocyanate. In the laminating process, the surface layer is coated and 5%-8% volatile matter is reserved, and then the surface layer is cold-pressed into the surface layer of the base cloth, and then radio frequency treatment is performed to utilize the dielectric loss difference to heat the interface, trigger the deblocking crosslinking and in-situ micro-foaming, and meanwhile the center of the base cloth is kept below the glass transition temperature. In the application, the covalent bond is used to anchor and block the blooming of the blooming aid, and the in-situ foaming riveting avoids the thermal hardening of the base cloth, and excellent flame-retardant carbonization barrier and extremely high anti-fatigue peeling strength are given to the synthetic leather.

Description

Technical Field

[0001] This invention relates to the field of polyester-based plastics technology, and in particular to an environmentally friendly synthetic leather for automotive interiors based on polyester biodegradable plastics and its lamination process. Background Technology

[0002] As a crucial surface material for automotive interior components such as seat covers, door panels, and dashboards, synthetic leather's flame retardancy, aging resistance, mechanical strength, and environmental properties directly impact passenger safety and in-vehicle air quality. With increasingly stringent global environmental regulations, the use of biodegradable polyester to replace traditional non-biodegradable polyvinyl chloride (PVC) or conventional polyurethane (PU) base fabrics has become an industry trend. However, existing polyester-based synthetic leather for automotive interiors still faces the following insurmountable technical bottlenecks in its use and processing:

[0003] First, to meet the stringent flame-retardant and anti-aging standards for automotive interiors, large amounts of small-molecule flame retardants and anti-aging agents are typically physically blended into the polyester base fabric. In the high-temperature environment of a car cabin during summer (reaching over 80°C), these small-molecule additives are highly susceptible to thermodynamically driven migration and precipitation (i.e., "frost" or "whitening"), which not only severely damages the appearance of the synthetic leather but also causes a sharp decline in the material's mechanical and flame-retardant properties over time. Furthermore, the addition of traditional flame retardants significantly increases the viscosity of the polyester melt, disrupting the polyester's spinning flowability and leading to difficulties in fiber forming and a high breakage rate in the base fabric.

[0004] Secondly, synthetic leather is typically composed of a surface resin layer and a base fabric. In actual automotive use, the intense thermal expansion and contraction within the vehicle and the stress fluctuations caused by frequent sitting and standing by passengers easily lead to stress concentration at the interface between the synthetic leather surface and the base fabric, resulting in fatigue delamination. Traditional heat-bonding processes often heat the entire base fabric, causing thermal shrinkage of the polyester chains, further weakening the interlayer peel strength and the original flexibility of the base fabric.

[0005] Finally, when existing synthetic leather is exposed to fire, the surface polyurethane resin is prone to melting and dripping. These drips not only ignite surrounding combustibles and cause the fire to spread, but the surface resin also cannot effectively interact with the flame-retardant system inside the base fabric, resulting in a significant decrease in the overall flame-retardant performance of the synthetic leather.

[0006] Therefore, it is necessary to provide an environmentally friendly synthetic leather for automotive interiors based on polyester biodegradable plastics and its lamination process to solve the above problems. Summary of the Invention

[0007] This invention overcomes the shortcomings of the prior art and provides an environmentally friendly synthetic leather for automotive interiors based on polyester biodegradable plastics and its lamination process.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] In a first aspect, a method for preparing polyester biodegradable plastics is provided, comprising the following steps:

[0010] S1. Mix raw materials containing aromatic diacid esters, aliphatic diacid esters, aliphatic diols and diols containing carbon-carbon double bonds, add a catalyst and perform melt polycondensation to obtain a modified polyester with carbon-carbon double bonds in the main chain.

[0011] S2. A mixture of lignin and a phosphorus-containing compound is reacted to obtain phosphorus-modified lignin.

[0012] S3. The modified polyester obtained in step S1, the phosphorus-containing modified lignin obtained in step S2, melamine, hindered amine anti-aging agent, low molecular weight polyethylene glycol and free radical initiator are mixed and subjected to melt reactive extrusion to obtain polyester biodegradable plastic.

[0013] In a preferred embodiment of the present invention, in step S1, the raw materials include diethyl terephthalate, dimethyl adipate, 1,4-butanediol and 1,4-butenediol, with a mass ratio of 1:0.7-0.9:1.1-1.3:0.2-0.4;

[0014] In step S2, the lignin is bamboo alkali lignin, and the phosphorus-containing compound is diethyl phosphite, with a mass ratio of 1:0.4-0.6.

[0015] In step S3, the mass ratio of the modified polyester, phosphorus-containing modified lignin, melamine, hindered amine anti-aging agent and low molecular weight polyethylene glycol is 100:12-18:1-3:4-6:2-4.

[0016] In a preferred embodiment of the present invention, in step S1, the catalyst is tetrabutyl titanate, and its addition amount is 0.1-0.5% of the total mass of the raw materials; the melt polycondensation temperature is 180-190°C, and the time is 3-5 hours;

[0017] In step S2, the reaction is carried out at 110-130°C for 1.5-2.5 hours.

[0018] In a preferred embodiment of the present invention, in step S3, the melt reactive extrusion is carried out in a twin-screw extruder, and the temperature of the reaction section is controlled at 180-190°C and the screw speed is 250-350 r / min.

[0019] In a preferred embodiment of the present invention, in step S3, the weight-average molecular weight of the low molecular weight polyethylene glycol is 400-1000 Da.

[0020] The free radical initiator is selected from dicumyl peroxide or benzoyl peroxide, and its addition amount is 0.05-0.2% of the mass of the modified polyester.

[0021] In a preferred embodiment of the present invention, in step S3, the hindered amine anti-aging agent is selected from one or more of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate or poly{[6-[(1,1,3,3-tetramethylbutyl)amino]-1,3,5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidinyl)imino]-1,6-hexadiyl[(2,2,6,6-tetramethyl-4-piperidinyl)imino]}.

[0022] In a preferred embodiment of the present invention, step S4 is further included: feeding the polyester biodegradable plastic obtained in step S3 into a melt spinning device for extrusion spinning, and then obtaining a nonwoven base fabric through a web-forming process.

[0023] 7. An environmentally friendly synthetic leather for automotive interiors based on polyester biodegradable plastics, characterized in that the synthetic leather comprises: a nonwoven fabric base made of the polyester biodegradable plastics as described in claim 1, and a polyurethane surface layer laminated on the surface of the nonwoven fabric base.

[0024] The polyurethane surface layer is made of a waterborne polyurethane slurry containing terminal siloxane groups with blocked isocyanate groups.

[0025] Secondly, an environmentally friendly automotive interior synthetic leather based on polyester biodegradable plastic is provided, the synthetic leather comprising: a non-woven fabric base made of the aforementioned polyester biodegradable plastic, and a polyurethane surface layer laminated on the surface of the non-woven fabric base.

[0026] The polyurethane surface layer is made of a waterborne polyurethane slurry containing terminal siloxane groups with blocked isocyanate groups.

[0027] Thirdly, a lamination process for environmentally friendly automotive interior synthetic leather is provided, comprising the following steps:

[0028] Step A: The terminal siloxane-based waterborne polyurethane slurry containing blocked isocyanate groups is coated onto a release carrier and partially dried, controlling the coating to retain 5%-8% of volatile matter to form a preliminary gel surface layer.

[0029] Step B: The initial gel surface layer is bonded to the nonwoven base fabric, and then cold-pressed by a cold press roller to press the initial gel surface layer into the surface layer of the nonwoven base fabric to obtain a composite.

[0030] Step C: The cold-pressed composite is placed in an RF heating device for high-frequency RF treatment. The difference in dielectric loss is used to raise the interface temperature between the initial gel surface layer and the nonwoven fabric base to above the unsealing temperature of the closed isocyanate groups, triggering chemical cross-linking and causing the retained moisture to micro-foam in situ. At the same time, the center temperature of the nonwoven fabric base is controlled to be kept below the glass transition temperature of the polyester.

[0031] Step D: After holding the pressure and cooling to room temperature, peel off the release carrier to obtain the environmentally friendly automotive interior synthetic leather.

[0032] In a preferred embodiment of the present invention, in step A, the temperature of the incomplete drying is 60-70°C, the release carrier is release paper with a leather texture, and the coating thickness of the slurry is 0.3-0.8 mm.

[0033] In step B, the ambient temperature for cold pressing is 25-30℃, the cold pressing pressure is 2-4MPa, and the depth of pressing into the surface of the nonwoven fabric base is 0.1-0.2mm.

[0034] In a preferred embodiment of the present invention, in step C, the frequency of the radio frequency heating is 27.12MHz, the processing time is 15-20 seconds, the interface temperature rises to 160-170℃, and the center temperature of the nonwoven fabric base is kept below 80℃.

[0035] In step D, the pressure of the pressure holding and cooling is 1-2 MPa, and the cooling rate is 15-25 °C / min.

[0036] This invention addresses the shortcomings of the prior art and has the following beneficial effects:

[0037] (1) This invention couples the covalent grafting of the polyester main chain with the radio frequency foaming lamination process that retains volatiles. Large-volume phosphorus-containing lignin and hindered amines are covalently anchored on the carbon skeleton to construct a dynamic cross-linked network. Water molecules trapped by lamination and polar bonds undergo polarization friction under a high-frequency electric field, triggering an interfacial heat explosion. Free highly active groups capture the lignin hydroxyl groups of the base fabric to form a network, and simultaneously stimulate water vaporization to expand and form a micron-sized closed-pore structure. The high activation energy barrier of covalent bonds strongly restricts the Brownian motion of the additives, and relies on electromagnetic thermal phase change and chemical reaction to construct a chemically cross-linked foaming mechanical riveting composite locking layer on the shallow surface. Existing physical blending additives are prone to volume expansion and surface diffusion crystallization under thermodynamic drive at high temperatures. Traditional heat conduction bonding promotes deep capillary penetration of resin, locking fiber movement and causing overall thermal shrinkage. This invention cuts off the frosting migration path of the additives, and under the premise of avoiding the thermal hardening of the base fabric and loss of mechanical freedom, enables the synthetic leather to have both a cross-layer flame-retardant charring barrier and extremely high fatigue-resistant interfacial peel strength.

[0038] (2) This invention introduces a double-bonded diol during the polymerization stage, and in the extrusion field, phosphorus-containing lignin is grafted onto the polyester backbone via free radical initiation. High-temperature, high-shear macromolecular addition binds rigid, large-volume molecules to the carbon skeleton. The constructed long-branched dynamic cross-linked network undergoes chain segment deentanglement under high shear stress during spinning, resulting in a shear-thinning effect. Its covalent fracture energy barrier completely blocks the outflow channels of additives caused by chain segment creep in the amorphous region. This mechanism counteracts the surge in melt viscosity caused by rigid lignin, allowing the solid phase component to maintain high-speed fluidity at the spinneret orifice. Existing conventional technologies for physically mixing small-molecule flame-retardant systems are prone to migrating down the concentration gradient to the surface and damaging the interior appearance under sustained high temperatures of 80°C. Particulate matter further damages the spinning rheology, causing stress concentration. This invention eliminates the persistent problem of frosting and whitening of automotive interiors under prolonged high-temperature exposure, suppresses the molding breakage phenomenon caused by melt fracture, and ensures the continuity of flame-retardant base fabric spinning production.

[0039] (3) In this invention, waterborne polyurethane is coated and 5% or 8% of volatile matter is retained. After cold pressing at room temperature to penetrate 0.1-0.2 mm into the surface layer of the base fabric, a high-frequency radio frequency alternating electromagnetic field is applied. Microwaves penetrate the weakly polar polyester matrix without dielectric loss. The polarized friction heating at the moisture-rich interface is targeted to stimulate the sealing agent to unblock the hydroxyl groups at the interface. The core temperature of the nonwoven fabric is clamped below 80°C by the thermal conduction hysteresis effect. The transient energy excitation of the difference in microscopic dielectric loss causes the polyurethane network to crosslink and solidify only in the shallow pores, locking the spatial configuration. Traditional full-width heat conduction forces the enthalpy to penetrate into the deep layer of the base fabric, causing the polyester macromolecules to pyrolyze and shrink. The heated resin deeply wets and binds the interwoven fiber nodes. This invention retains the relative sliding freedom of the bottom fiber space and maintains the cold flexibility of the material, blocks the path of polymer thermal damage and degradation, and eliminates the interface peeling and delamination defects caused by frequent alternating friction.

[0040] (4) The lamination of this invention causes the trapped moisture at the interface to undergo phase change and vaporization at local high temperature. It is then encapsulated by the rapidly cross-linked polyurethane network and expanded in situ to form a dense closed-cell structure of 10-50 μm. Mechanical forced cooling forces the internal high-pressure water vapor to condense and solidify, constructing a micro-elastic heat insulation network rich in polar bonds and flame-retardant groups at the interface, which greatly dissipates and buffers the external dynamic cross-shear stress. Existing solid dense coatings have no buffering space for dissipating concentrated stress, and are very prone to fatigue microcracks at rigid interfaces. When exposed to open flame, the surface resin quickly absorbs heat enthalpy, melts and drips, igniting the surrounding area. This invention relies on polarization heating to reshape the interface morphology in situ, giving the synthetic leather the toughness to withstand 100,000 folds without breaking. It also uses the closed-cell air layer and phosphorus-rich skeleton to synergistically suppress solid-phase heat conduction, cutting off the risk of polyurethane surface layer melting and dripping and secondary ignition. Attached Figure Description

[0041] 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.

[0042] Figure 1 This is a flowchart of the preparation method of the polyester biodegradable plastic of the present invention;

[0043] Figure 2 This is a flow chart of the lamination process for the environmentally friendly automotive interior synthetic leather of the present invention. Detailed Implementation

[0044] 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.

[0045] 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.

[0046] The polyester biodegradable plastics and nonwoven fabrics prepared therefrom described in this invention are specifically designed for deployment environments within automotive cabins. This scenario requires materials to withstand long-term high-temperature radiation exceeding 80°C inside the vehicle during summer, while also withstanding alternating stresses caused by frequent sitting and standing by passengers. Furthermore, it must meet stringent halogen-free flame-retardant standards and regulations for the biodegradability and recycling of end-of-life automotive materials.

[0047] The sources of the basic raw materials and modifying agents involved in implementing this invention are as follows:

[0048] Materials procured: Aromatic diacid esters were diethyl terephthalate (DET), purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., with a purity ≥99.0%; Aliphatic diacid esters were dimethyl adipate (DMA), purchased from Sinopharm Chemical Reagent Co., Ltd., analytical grade, with a purity ≥99.5%; Aliphatic diols were 1,4-butanediol (BDO), purchased from Tianjin Hengxing Chemical Reagent Manufacturing Co., Ltd., with a purity ≥99.0%; Diols containing carbon-carbon double bonds were 1,4-butenediol, purchased from Shanghai Maclean Biochemical Technology Co., Ltd., with a purity ≥98.0%; Catalysts were tetrabutyl titanate (TBT), purchased from Sinopharm Chemical Reagent Co., Ltd., analytical grade; Flame retardant framework precursors were bamboo alkali lignin, purchased from Shandong Longli Biotechnology Co., Ltd., weight-average. The molecular weight distribution is precisely between 5000-8000 Da, and the hydroxyl content is ≥2.5 mmol / g; the phosphorus-containing compound is diethyl phosphite, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., with a purity ≥98.0%; the flame retardant synergist is melamine (Sinopharm Group, analytical grade); the hindered amine anti-aging agent is UV-770 bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate from BASF (China) Co., Ltd., or the light stabilizer 944 with equivalent activity; the macromolecular dispersant is low molecular weight polyethylene glycol (PEG-600), with a weight average molecular weight of 600 Da; the free radical initiator is dicumyl peroxide (DCP) or benzoyl peroxide (BPO), purchased from Shanghai Maclean Biochemical Technology Co., Ltd.; anhydrous ethanol and other common washing solvents are all commercially available analytical grade.

[0049] To meet the grafting activity requirements of subsequent reactive extrusion, this invention requires the pre-preparation of highly active phosphorus-modified lignin. The specific preparation steps are as follows: Vacuum-dried bamboo alkali lignin and diethyl phosphite are precisely weighed at a mass ratio of 1:0.5 and placed into a pressure-resistant reactor equipped with a reflux condenser and a heat-conducting oil heating jacket. High-purity nitrogen is introduced to purge the air from the reactor three times to ensure an absolutely oxygen-free environment. Stirring is started and maintained at a constant speed of 200 r / min. The system is then heated to 120°C at a rate of 3°C / min and held at this temperature for a precise 2.0 hours. After the reaction, the product is transferred to a centrifuge, washed four times with anhydrous ethanol, and finally dried to constant weight in a 60°C vacuum double-cone dryer to obtain modified lignin powder.

[0050] like Figure 1 As shown, a method for preparing a polyester biodegradable plastic includes the following steps:

[0051] S1. Mix raw materials containing aromatic diacid esters, aliphatic diacid esters, aliphatic diols and diols containing carbon-carbon double bonds, add a catalyst and perform melt polycondensation to obtain a modified polyester with carbon-carbon double bonds in the main chain.

[0052] S2. A mixture of lignin and a phosphorus-containing compound is reacted to obtain phosphorus-modified lignin.

[0053] S3. The modified polyester obtained in step S1, the phosphorus-containing modified lignin obtained in step S2, melamine, hindered amine anti-aging agent, low molecular weight polyethylene glycol and free radical initiator are mixed and subjected to melt reactive extrusion; through free radical addition reaction, the phosphorus-containing modified lignin and hindered amine anti-aging agent are grafted onto the carbon-carbon double bonds of the modified polyester main chain to obtain polyester biodegradable plastic.

[0054] The core concept of this invention lies in blocking the migration path of small-molecule additives from a thermodynamic perspective through pre-designed molecular structures and strong intervention in chemical bonding. Traditional techniques involve physically blending flame retardants and anti-aging agents. At a sustained high temperature of 80°C, the matrix expands freely, and the additives are easily driven by concentration gradients to migrate and precipitate on the surface, forming crystals. This invention actively introduces 1,4-butenediol during the polyester polymerization stage to provide carbon-carbon double bond anchors. Subsequently, in the high-temperature, high-shear field of a twin-screw extruder, a free radical initiator breaks the active hydrogens on the macromolecular chain, triggering an addition reaction. This permanently anchors large volumes of phosphorus-containing lignin and hindered amine molecules to the polyester backbone via covalent bonds. This mechanism not only completely eliminates interfacial blooming but also constructs a long-branched dynamic cross-linked network with lignin nodes within the polyester melt. Under the high shear forces of subsequent spinning, this network undergoes chain segment deentanglement, exhibiting a strong shear-thinning effect, thereby offsetting the viscosity surge caused by rigid fillers and ensuring the stability of the melt's processing rheological properties.

[0055] To achieve the aforementioned microscopic mechanism, the specific process steps are strictly limited as follows:

[0056] In step S1, the mass ratio of diethyl terephthalate, dimethyl adipate, 1,4-butanediol and 1,4-butenediol must be controlled at 1:(0.7-0.9):(1.1-1.3):(0.2-0.4).

[0057] Specifically, diethyl terephthalate provides a rigid benzene ring to maintain mechanical strength, dimethyl adipate imparts flexibility and degradable sites to the molecular chain, and the ratio of 1,4-butenediol is extremely critical: if it is below 0.2, the lack of double bond density leads to insufficient subsequent grafting rate; if it is above 0.4, the macromolecular chain is too rigid, which can easily trigger thermal self-crosslinking of free double bonds during the polycondensation stage, resulting in melt gelation.

[0058] Furthermore, tetrabutyl titanate is added as a catalyst at a ratio of 0.1-0.5% of the total raw material mass. The melt polycondensation temperature needs to be precisely controlled at 180-190℃, and the reaction should last for 3-5 hours. Temperatures below 180℃ will cause a sharp decrease in the probability of end-group collisions, making it impossible to achieve the required degree of polymerization; temperatures above 190℃ will trigger excessive cross-linking of double bonds induced by the titanium catalyst.

[0059] In step S2, if a broad-spectrum preparation method other than the self-made embodiment described above is used, the mass ratio of bamboo alkali lignin to diethyl phosphite needs to be controlled between 1:(0.4-0.6), and the reaction should be carried out at 110-130℃ for 1.5-2.5 hours under nitrogen protection and a stirring speed of 150-250 r / min.

[0060] Within this thermodynamic range, the POC bond of diethyl phosphite breaks, undergoing an irreversible transesterification reaction with the aliphatic and phenolic hydroxyl groups in the lignin structure and releasing ethanol, thereby loading phosphorus elements onto the char-forming framework at a high density.

[0061] In step S3, modified polyester, phosphorus-containing modified lignin, melamine, hindered amine anti-aging agent selected from bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate or light stabilizer 944), and low molecular weight polyethylene glycol with a weight average molecular weight of 400-1000 Da are placed in a high-speed mixer for premixing at a mass ratio of 100:(12-18):(1-3):(4-6):(2-4).

[0062] Subsequently, 0.05-0.2% (by weight of the modified polyester) of a free radical initiator (dicumyl peroxide or benzoyl peroxide) is added. The material is fed into a twin-screw extruder at a constant rate, with the reaction zone temperature set at 180-190℃ and the screw speed maintained at a high speed range of 250-350 r / min. In this high-temperature and strong shear coupled field, the primary free radicals generated by the homolytic cracking of the initiator preferentially abstract active hydrogens from lignin or hindered amines, and the resulting macromolecular free radicals rapidly attack the double bonds on the polyester backbone, completing the reactive extrusion grafting.

[0063] In step S4, the biodegradable polyester plastic obtained in step S3 is fed into a melt spinning device for extrusion spinning. Due to the rheological abrupt change characteristics imparted by the aforementioned dynamic branched network, even if the melt contains a large amount of solid components such as lignin, it still exhibits excellent flowability when flowing through micron-sized spinnerets, effectively suppressing melt fracture and breakage caused by stress concentration. After cooling and high-speed airflow drawing, the filaments are fixed into a web through a hot rolling mill or cross-needling equipment with a hot rolling temperature set at 130-150℃, ultimately producing a tightly interwoven nonwoven fabric base. At this point, all functional macromolecules are chemically locked within the network of crystalline and amorphous regions of the fiber.

[0064] This invention introduces aliphatic carbon-carbon double-bonded diols during the polyester synthesis stage and grafts phosphorus-modified lignin and hindered amine anti-aging agents onto the modified polyester backbone in a twin-screw extrusion process using a free radical initiator. This allows large-volume auxiliary molecules to be covalently anchored to the nodes of the long-chain carbon skeleton, constructing a long-branched dynamic cross-linked network. This network restricts the Brownian motion diffusion of auxiliary molecules with an extremely high fracture activation energy barrier, blocking the free migration path of small-molecule auxiliary agents under high-temperature conditions. Existing technologies, by physically blending flame retardants, readily migrate and crystallize to the surface under thermodynamic drive in high-temperature cabin environments, thus avoiding blooming on the surface of synthetic leather and ensuring the long-term stability of the material's mechanical and flame-retardant properties.

[0065] The environmentally friendly automotive interior synthetic leather and its lamination process described in this invention are specifically developed for the automotive cabin environment, primarily applicable to high-frequency contact and sun-exposed areas such as car seat covers, door trim panels, dashboard coverings, and steering wheel covers. This scenario demands that the material not peel or delaminate at the interface under frequent alternating frictional shear forces, and that it rapidly constructs a microscopic heat-insulating carbon layer to suppress molten dripping in the event of a fire, while also considering its environmentally friendly degradation properties at the end of its life cycle.

[0066] The key material sources and specific parameters involved in the lamination process of this invention are as follows:

[0067] Materials procured: The surface coating resin is a waterborne polyurethane slurry with terminal siloxane groups containing blocked isocyanate groups, procured from Wanhua Chemical Group Co., Ltd. WANNATE® series custom waterborne resin is selected, with a factory solid content of 45% and an isocyanate group unblocking temperature set at 150℃. Polydimethylsiloxane segments are introduced into the end groups through copolymerization. The release carrier is R-105 type high-grade release paper with a specific calfskin texture, procured from Sappi Corporation, USA.

[0068] The underlying skeleton material required for lamination is prepared using a biodegradable polyester plastic with a main chain containing double bonds and grafted with a flame-retardant and anti-aging network, obtained by the aforementioned preparation method. Specifically, the preparation parameters are as follows: the polyester masterbatch obtained from reactive extrusion granulation in the aforementioned examples is continuously fed into a melt spinning device. The temperatures of each zone of the extruder barrel are set to 180℃, 185℃, and 185℃ sequentially. After being metered by a high-precision metering pump, the melt is pressed into a microporous spinneret at a constant extrusion pressure of 100MPa. The continuously extruded fine stream is cooled by a side-blowing airflow at 18℃ and stretched by a high-speed airflow at 2500m / min, then evenly spread onto a web forming curtain. Subsequently, the composite web layer enters an industrial hot rolling mill, where localized fiber melting and bonding occur under the mechanical hot pressing action of a hot rolling roll surface temperature of 140℃ and a linear pressure of 65N / mm. Finally, a nonwoven base fabric with a surface density precisely controlled at 220g / m² and a tightly three-dimensional interwoven internal fiber structure is obtained.

[0069] like Figure 2 As shown, a lamination process for environmentally friendly automotive interior synthetic leather includes the following steps:

[0070] Step A: The terminal siloxane-based waterborne polyurethane slurry containing blocked isocyanate groups is coated onto a release carrier and partially dried, controlling the coating to retain 5%-8% of volatile matter to form a preliminary gel surface layer.

[0071] Step B: The initial gel surface layer is bonded to the nonwoven base fabric, and then cold-pressed by a cold press roller to press the initial gel surface layer into the surface layer of the nonwoven base fabric to obtain a composite.

[0072] Step C: The cold-pressed composite is placed in an RF heating device for high-frequency RF treatment. The difference in dielectric loss is used to raise the interface temperature between the initial gel surface layer and the nonwoven fabric base to above the unsealing temperature of the closed isocyanate groups, triggering chemical cross-linking and causing the retained moisture to micro-foam in situ. At the same time, the center temperature of the nonwoven fabric base is controlled to be kept below the glass transition temperature of the polyester.

[0073] Step D: After holding the pressure and cooling to room temperature, peel off the release carrier to obtain the environmentally friendly automotive interior synthetic leather.

[0074] The core concept of this lamination process lies in abandoning the traditional full-area heat conduction bonding mode and instead utilizing the significant differences in the microscopic dielectric loss characteristics of materials to construct a phase change and reaction coupling system of "incomplete drying + cold pressing penetration + radio frequency selective heating". Through the penetrating power of radio frequency electromagnetic waves, heat is instantaneously released only at the contact interface of a few hundred micrometers containing polar water molecules and polyurethane segments. This in-situ instantaneous thermal excitation phenomenon not only unblocks the closed isocyanate groups and causes a nucleophilic addition reaction with the lignin hydroxyl groups on the base fabric surface to form covalent bonds, but also triggers the rapid vaporization of retained moisture, expanding the cross-linked network to form a micron-level closed-cell foam layer. Since the base fabric does not absorb radio frequency energy, its macromolecular segments are not affected by pyrolysis orientation and thermal shrinkage, thus giving the interface extremely high peel strength while perfectly retaining the original mechanical freedom and soft touch of the underlying fiber framework.

[0075] In step A, the aforementioned waterborne polyurethane slurry containing closed isocyanate groups and terminal siloxane groups is uniformly coated onto the surface of a release paper with a leather-textured surface using a slot extrusion coating machine. The coating thickness of the wet film slurry must be precisely limited to between 0.3 and 0.8 mm. Subsequently, the carrier and coating are placed in a gradient oven for incomplete drying within a mild temperature range of 60-70°C. During this process, excessive moisture evaporation is strictly controlled by frequently adjusting the airflow and conveyor belt speed, ensuring that the coating retains 5%-8% of volatile matter (mainly water molecules).

[0076] The critical significance of this volatile content range lies in its ability to both promote the fusion of latex particles to form a nascent gel layer that has lost its macroscopic fluidity and provide a sufficient material basis for subsequent radio frequency polarization heating and vapor pore formation. If the volatile content is below 5%, the lack of interfacial medium will prevent heat generation and foaming; if it is above 8%, excess free water will cause uncontrollable deep capillary penetration of the adhesive into the base fabric.

[0077] In step B, the release paper with the initial gel layer and the aforementioned self-prepared nonwoven base fabric are simultaneously introduced into a high-precision cold-pressing composite system. At an ambient temperature of 25-30°C, a purely mechanical linear pressure of 2-4 MPa is applied by a cold-pressing roller that has undergone surface hardening treatment.

[0078] Because the gel layer maintains a high viscosity at this temperature, under forced pressure of 2-4 MPa, the polyurethane resin is precisely pressed into the pore network of the surface fibers of the nonwoven fabric base, with the pressing depth strictly fixed at 0.1-0.2 mm. This millimeter-level penetration control successfully constructs a three-dimensional mechanical rivet structure at the two-phase interface, while simultaneously preventing the resin from spreading and locking into the deep fiber nodes of the base fabric, ensuring over 90% relative sliding freedom of the underlying fibers in spatial dimensions.

[0079] In step C, the composite is then continuously passed through an industrial-grade flat-plate radio frequency heating device and placed in a radio frequency electromagnetic field with a frequency set to 27.12MHz for 15-20 seconds.

[0080] Under this high-frequency alternating electric field, the weakly polar polyester fiber matrix undergoes electromagnetic wave penetration with almost no dielectric energy loss. Meanwhile, the polar water molecules and urethane bonds enriched in the interfacial region, with a penetration depth of 0.1-0.2 mm, experience intense dipole polarization and friction, triggering an in-situ heat release. Within just 15-20 seconds, the local interfacial temperature soars to 160-170°C, exceeding the 150°C desealing threshold of the sealing agent. The released highly active -NCO groups instantly capture the exposed phosphorus-containing lignin hydroxyl groups on the base fabric surface, forming a robust urethane covalent network.

[0081] Simultaneously, the retained 5%-8% moisture rapidly vaporizes at 160℃, encapsulating the rapidly cross-linking and curing polyurethane network, and forming a dense micron-sized closed-pore structure with a diameter of 10-50μm at the interface. Throughout the excitation process, due to the time lag effect of heat conduction, the absolute temperature of the central region of the nonwoven fabric base is always kept below 80℃, far below the relaxation temperature of the polyester macromolecular chain segments, effectively avoiding the thermal curing phenomenon of the base fabric.

[0082] In step D, the composite that has undergone radio frequency excitation is still in a state of high vapor pressure and exothermic cross-linking within micropores, and must be quickly transferred to the cooling roller zone. A holding pressure of 1-2 MPa is applied, and the material is rapidly cooled to room temperature at a forced cooling rate of 15-25 °C / min under the action of internal circulating water.

[0083] The continuous application of holding pressure forces the liquid polyurethane to fill the microstructure of the release paper, achieving micron-level replication of the leather texture. Forced cooling, while quenching free radical chemical reactions, forces the water vapor inside the micropores to condense and depressurize, preventing the foam walls from collapsing or rupturing. Finally, the release paper is peeled off at the winding station, resulting in an environmentally friendly synthetic leather product for automotive interiors that combines resistance to high-temperature migration, excellent flexibility, and a multi-layered flame-retardant barrier.

[0084] This invention controls the coating of terminal siloxane-based waterborne polyurethane slurry containing closed isocyanate groups during the lamination process, retaining volatile components to form an initial gel surface layer. After cold pressing into the surface of the nonwoven fabric base, it is treated with a high-frequency electromagnetic field using radio frequency heating equipment. Under the high-frequency alternating electric field, the intense dipole polarization and friction of polar water molecules and urethane bonds triggers an in-situ burst of heat at the interface, causing a local instantaneous temperature rise that stimulates the desealing of isocyanate and covalent cross-linking with lignin hydroxyl groups. At the same time, relying on the time lag effect of heat conduction, the temperature of the center of the nonwoven fabric base is kept below the glass transition temperature, achieving simultaneous locking of three-dimensional mechanical riveting and chemical bonding of the shallow resin layer. Traditional full-width heat conduction bonding process causes heat to slowly penetrate into the deep layers of the base fabric, causing irreversible thermal shrinkage of polyester segments and disorientation of polymer chains. The resin softened by heat undergoes deep penetration and wetting, locking the relative sliding freedom between fibers. Thus, while giving the synthetic leather interface high peel strength, it retains the original mechanical freedom and soft touch of the underlying fiber framework and avoids fatigue delamination.

[0085] Example 1:

[0086] This embodiment prepares environmentally friendly automotive interior synthetic leather based on the above-mentioned method for preparing a polyester biodegradable plastic and a lamination process for environmentally friendly automotive interior synthetic leather, including the following steps:

[0087] Step S1: Diethyl terephthalate, dimethyl adipate, 1,4-butanediol, and 1,4-butenediol were accurately weighed in a mass ratio of 1:0.8:1.2:0.3 and added to a polycondensation reactor. 0.3% (by mass) of tetrabutyl titanate catalyst was added. The mixture was melt-polymerized at 185°C under high vacuum for 4.0 hours to obtain a modified polyester with carbon-carbon double bonds in its main chain.

[0088] Step S2: According to the aforementioned self-made example, bamboo alkali lignin and diethyl phosphite were reacted at a ratio of 1:0.5 to obtain phosphorus-modified lignin.

[0089] Step S3: The obtained modified polyester, phosphorus-containing modified lignin, melamine, UV-770 anti-aging agent, and PEG-600 are mixed in a mass ratio of 100:15:2:5:3, and 0.1% of dicumyl peroxide (DCP) by weight of the polyester is added. The mixture is fed into a twin-screw extruder and subjected to free radical addition grafting under a strong shear field of 185℃ and 300r / min to granulate and obtain biodegradable plastic masterbatch.

[0090] Step S4: The masterbatch is extruded and spun at 185℃ and 100MPa, and then hot-rolled and fixed at 140℃ to obtain a nonwoven base fabric with an areal density of 220g / m².

[0091] Lamination Process (AD): Aqueous polyurethane slurry is coated onto release paper, with the wet film thickness controlled at 0.5 mm. After incomplete drying at 65°C, a near-infrared moisture meter is used for closed-loop control to precisely retain 6.5% of the volatile components. Cold pressing is then applied at 28°C with a mechanical pressure of 3.0 MPa, pressing the gel layer into the base fabric surface by 0.15 mm. Subsequently, it is treated in a 27.12 MHz radio frequency field for 18 seconds (the measured instantaneous maximum temperature at the interface was 165°C, and the core temperature of the base fabric was approximately 72°C). Finally, it is cooled and set at 1.5 MPa at 20°C / min, and then peeled off to obtain synthetic leather.

[0092] Example 2:

[0093] The only difference from Example 1 is that in step S1, the mass ratio of 1,4-butenediol is adjusted to 0.2, that is, the mass ratio of aromatic diacid ester, aliphatic diacid ester, aliphatic diol and diol containing double bond is set to 1:0.8:1.2:0.2.

[0094] Example 3:

[0095] The only difference from Example 1 is that in step S1, the mass ratio of 1,4-butenediol is adjusted to 0.4, that is, the mass ratio of aromatic diacid ester, aliphatic diacid ester, aliphatic diol and diol containing double bond is set to 1:0.8:1.2:0.4.

[0096] Example 4:

[0097] The only difference from Example 1 is that in step S3, the amount of phosphorus-modified lignin added is adjusted to 12 parts.

[0098] Example 5:

[0099] The only difference from Example 1 is that in step S3, the amount of phosphorus-modified lignin added is adjusted to 18 parts.

[0100] Example 6:

[0101] The only difference from Example 1 is that in step S3, the amount of phosphorus-modified lignin added is adjusted to 8 parts.

[0102] Example 7:

[0103] The only difference from Example 1 is that in step S3, the amount of phosphorus-modified lignin added is adjusted to 22 parts.

[0104] Comparative Example 1:

[0105] The only difference from Example 1 is that in step S1, 1,4-butenediol is completely removed and replaced with an equal mass fraction of 1,4-butanediol. All other formulations and processes are completely consistent with Example 1.

[0106] Comparative Example 2:

[0107] The only difference from Example 1 is that in step C of the lamination process, the radio frequency heating equipment is abandoned, and the cold-pressed composite is directly introduced into a traditional industrial high-temperature hot press steel roller. The surface temperature of the hot press roller is kept constant at 165°C, and the contact heat transfer time is also kept at 18 seconds. All other formulations and processes are completely consistent with Example 1.

[0108] Comparative Example 3:

[0109] The only difference from Example 1 is that in step A of the lamination process, the belt speed of the gradient oven is finely adjusted to slightly extend the drying dwell time, so that the volatile matter retained in the initial gel surface layer is precisely reduced to 4.5%.

[0110] Comparative Example 4:

[0111] The only difference from Example 1 is that in step A, the belt speed is slightly adjusted to shorten the drying time, so that the volatile matter retained by the coating reaches 8.5%.

[0112] Comparative Example 5:

[0113] The only difference from Example 1 is that in step S3, the twin-screw reactive extrusion process is abandoned. Instead, the modified polyester, phosphorus-containing modified lignin and various additives are mixed evenly in a conventional high-speed mixer and then directly subjected to physical melt mixing and granulation under lower shear force through a conventional single-screw extruder.

[0114] The polyester masterbatch and synthetic leather prepared in the above embodiments and comparative examples were tested as follows:

[0115] High-temperature thermal aging color difference test: Synthetic leather samples were placed in an 85℃ forced-air drying oven for continuous aging for 500 h. Color data before and after aging were measured using a colorimeter, and the total color difference ΔE was calculated. This index is used to quantitatively evaluate the degree of migration of auxiliaries to the surface; the smaller the ΔE, the stronger the anti-blooming performance.

[0116] 100,000-cycle Bally dynamic flexure test: In accordance with GB / T 8949 standard, the sample was subjected to 100,000 continuous flexures using a Bally flexure testing machine at room temperature. After completion, the damage was observed and recorded using a magnifying glass, and converted into quantitative values ​​according to the rating. A score of 10 indicates no cracks or delamination, and the lower the score, the more severe the damage.

[0117] Vertical burning drip test: Refer to the UL-94 vertical burning test method, ignite the sample for 10 seconds and then remove the fire source, and record the number of molten drips produced during the burning process.

[0118] Degradation test: Controlled industrial composting method was used (refer to GB / T 19277.1). The sample was buried in standard compost inoculum at 58℃ and removed after 90 days. After ultrasonic cleaning and drying, the sample was weighed and the percentage of mass loss (%) was calculated.

[0119] The specific experimental data are shown in Table 1 below.

[0120] Table 1. Summary of Sample Test Results

[0121]

[0122] As shown in the table above, after continuous baking at 85°C for 500 hours, the surface color difference ΔE in Example 1 was only 0.62, and the surface was smooth with no crystal precipitation visible to the naked eye. In contrast, the color difference in Comparative Example 5 increased to 4.82, and the color difference in Comparative Example 1 was as high as 4.25, macroscopically showing that the interface was completely covered by the precipitated white additives. The underlying mechanism is that the high temperature of 85°C drastically intensifies the creep of the polyester amorphous region chain segments, leading to the expansion of the free volume inside the matrix. In Comparative Examples 1 and 5, the free additive molecules, driven by the extremely high concentration gradient potential energy, easily flowed outward along the intergranular channels of the macromolecules. In contrast, Examples 1, 2, and 3 relied on the carbon-carbon double bonds introduced in the main chain to firmly bind the phosphorus-containing lignin and anti-aging agent to the nodes of the long-chain carbon skeleton through free radical reactions. The activation energy of breaking the macromolecular covalent bonds has an absolute energy barrier, far beyond the thermal energy of 85°C, locking the diffusion path of the additives at the root of kinetics.

[0123] In 100,000 Bally dynamic flexure tests, Example 1 showed no cracks or delamination, while Comparative Example 2 exhibited severe brittle peeling. This is because the conventional law of thermal conduction forces heat to slowly penetrate deep into the base fabric, triggering irreversible thermal shrinkage of the polyester segments and causing the softened resin to undergo deep capillary permeation, which, upon condensation, completely locks the relative sliding freedom between the three-dimensional fibers. Example 1, on the other hand, utilizes the difference in dielectric loss of high-frequency electromagnetic waves, with energy bursting instantaneously only in the 0.15μm shallow surface layer rich in polar water molecules and urethane bonds. While maintaining the core of the base fabric at 72°C cold-state flexibility, it not only stimulates chemical cross-linking but also promotes the in-situ vaporization of retained moisture, expanding the cross-linked network to form a micron-level closed-pore structure. This microscopic "spring network" greatly dissipates the alternating stress during dynamic flexure.

[0124] Table 1 shows that Comparative Example 3 had a peel score of 5.8 and dripped as many as 12 times. This was due to a deficiency in the number of polar water molecules, which not only resulted in insufficient RF dielectric enthalpy to completely unblock the isocyanate, but also the weak water vapor partial pressure was insufficient to expand the foam wall, leading to the failure of the physical insulation structure. Conversely, Comparative Example 4 not only had a tortuous score of 4.5, but also dripped 8 times. This was because the excess solvent caused uncontrolled deep penetration during cold pressing, and at the RF instant, the large water molecule phase change directly ruptured the cross-linking polyurethane network. The large-area ruptured series channels not only lost their heat-insulating effect, but also allowed liquid resin to overflow along the pores, destroying the flexible boundary of the leather surface.

[0125] Comparing Examples 4 and 5 with Examples 6 and 7, it can be seen that 12-18 parts per unit volume is the optimal range for achieving a balance in overall performance. When lignin is extremely deficient, although the material is highly flexible, the number of drips during combustion exceeds 10, indicating that the base fabric surface lacks sufficient phosphorus-based carbon sources and cannot form a dense heat-insulating carbon layer in conjunction with the surface resin. When lignin is overloaded, although zero dripping is achieved, the Bally tortuosity score plummets to 5.2. This is because the large number of rigid lignin benzene ring networks severely damages the flexibility of the aliphatic polyester chains, making the material extremely brittle under dynamic stress. In addition, the 90-day composting weight loss rate of all examples remained stable at over 89%, proving that the chemical modification and lamination process of this invention not only did not destroy the degradable sites of the aliphatic diacid esters, but also maintained excellent biodegradability through the introduction of lignin.

[0126] In summary, this invention achieves a breakthrough by coupling covalent grafting of main-chain double bonds with in-situ microfoaming induced by radio frequency dielectrics within a single material manufacturing cycle. The chemical anchoring at the macromolecular chain level completely overcomes the problem of additive blooming; simultaneously, by cleverly utilizing the phase transition polarization of volatile components, an interfacial foaming network is constructed that combines high-frequency tortuous stress dissipation with cross-level pyrolysis interference efficiency, while maintaining the cold-state physical properties of the underlying skeleton. This achieves multidimensional unity in the mechanical, flame-retardant, and life-cycle degradation aspects of environmentally friendly interior materials.

[0127] It should be specifically stated that the embodiments listed above are merely preferred embodiments of the present invention, intended to help those skilled in the art to more clearly understand the microscopic mechanisms and macroscopic effects of the present invention, and are not intended to absolutely limit the physical or chemical boundaries of the present invention. Those skilled in the art, after understanding the core technical essence of the present invention, can make equivalent substitutions, parameter shifts, or local fine-tunings to the raw material types, spatial parameters, thermodynamic or kinetic conditions given above, based on the specific working conditions of actual industrial production, without departing from the design concept of the present invention. Any modifications, equivalent substitutions, and evolutions made within the spirit and principles of the present invention should be unconditionally covered within the legal protection scope defined by the claims of the present invention.

Claims

1. A method for preparing a polyester biodegradable plastic, characterized in that, Includes the following steps: S1. Mix raw materials containing aromatic diacid esters, aliphatic diacid esters, aliphatic diols and diols containing carbon-carbon double bonds, add a catalyst and perform melt polycondensation to obtain a modified polyester with carbon-carbon double bonds in the main chain. S2. A mixture of lignin and a phosphorus-containing compound is reacted to obtain phosphorus-modified lignin. S3. The modified polyester obtained in step S1, the phosphorus-containing modified lignin obtained in step S2, melamine, hindered amine anti-aging agent, low molecular weight polyethylene glycol and free radical initiator are mixed and subjected to melt reactive extrusion to obtain polyester biodegradable plastic.

2. The method for preparing a polyester biodegradable plastic according to claim 1, characterized in that, In step S1, the raw materials include diethyl terephthalate, dimethyl adipate, 1,4-butanediol and 1,4-butenediol, with a mass ratio of 1:0.7-0.9:1.1-1.3:0.2-0.4; In step S2, the lignin is bamboo alkali lignin, and the phosphorus-containing compound is diethyl phosphite, with a mass ratio of 1:0.4-0.

6. In step S3, the mass ratio of the modified polyester, phosphorus-containing modified lignin, melamine, hindered amine anti-aging agent and low molecular weight polyethylene glycol is 100:12-18:1-3:4-6:2-4.

3. The method for preparing a polyester biodegradable plastic according to claim 1, characterized in that, In step S1, the catalyst is tetrabutyl titanate, and its addition amount is 0.1-0.5% of the total mass of the raw materials; the melt polycondensation temperature is 180-190℃, and the time is 3-5 hours; In step S2, the reaction is carried out at 110-130°C for 1.5-2.5 hours.

4. The method for preparing a polyester biodegradable plastic according to claim 1, characterized in that, In step S3, the melt reactive extrusion is carried out in a twin-screw extruder, with the temperature of the reaction section controlled at 180-190℃ and the screw speed at 250-350 r / min.

5. The method for preparing a polyester biodegradable plastic according to claim 1, characterized in that, In step S3, the weight-average molecular weight of the low molecular weight polyethylene glycol is 400-1000 Da; The free radical initiator is selected from dicumyl peroxide or benzoyl peroxide, and its addition amount is 0.05-0.2% of the mass of the modified polyester.

6. A method for preparing a polyester biodegradable plastic according to any one of claims 1-5, characterized in that, It also includes step S4: feeding the polyester biodegradable plastic obtained in step S3 into a melt spinning equipment for extrusion spinning, and then obtaining a nonwoven base fabric through a web-forming process.

7. An environmentally friendly synthetic leather for automotive interiors based on polyester biodegradable plastics, characterized in that, The synthetic leather comprises: a nonwoven base fabric made of the polyester biodegradable plastic as described in claim 1, and a polyurethane surface layer laminated on the surface of the nonwoven base fabric; The polyurethane surface layer is made of a waterborne polyurethane slurry containing terminal siloxane groups with blocked isocyanate groups.

8. A lamination process for the environmentally friendly automotive interior synthetic leather as described in claim 7, characterized in that, Includes the following steps: Step A: The terminal siloxane-based waterborne polyurethane slurry containing blocked isocyanate groups is coated onto a release carrier and partially dried, controlling the coating to retain 5%-8% of volatile matter to form a preliminary gel surface layer. Step B: The initial gel surface layer is bonded to the nonwoven base fabric, and then cold-pressed by a cold press roller to press the initial gel surface layer into the surface layer of the nonwoven base fabric to obtain a composite. Step C: The cold-pressed composite is placed in an RF heating device for high-frequency RF treatment. The difference in dielectric loss is used to raise the interface temperature between the initial gel surface layer and the nonwoven fabric base to above the unsealing temperature of the closed isocyanate groups, triggering chemical cross-linking and causing the retained moisture to micro-foam in situ. At the same time, the center temperature of the nonwoven fabric base is controlled to be kept below the glass transition temperature of the polyester. Step D: After holding the pressure and cooling to room temperature, peel off the release carrier to obtain the environmentally friendly automotive interior synthetic leather.

9. The lamination process for an environmentally friendly automotive interior synthetic leather according to claim 8, characterized in that, In step A, the temperature of the incomplete drying is 60-70℃, the release carrier is release paper with leather texture, and the coating thickness of the slurry is 0.3-0.8mm; In step B, the ambient temperature for cold pressing is 25-30℃, the cold pressing pressure is 2-4MPa, and the depth of pressing into the surface of the nonwoven fabric base is 0.1-0.2mm.

10. The lamination process for an environmentally friendly automotive interior synthetic leather according to claim 8, characterized in that, In step C, the frequency of the radio frequency heating is 27.12MHz, the processing time is 15-20 seconds, the interface temperature rises to 160-170℃, and the center temperature of the nonwoven fabric base is kept below 80℃. In step D, the pressure of the pressure holding and cooling is 1-2 MPa, and the cooling rate is 15-25 °C / min.

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