Low odor flame retardant automotive carpet composite and method of making

Abstract

The application discloses a low-odor flame-retardant automobile carpet composite material and a preparation method thereof, and belongs to the technical field of automobile interior materials, and aims to solve the technical problems that existing automobile carpets are difficult to achieve both flame retardation and low odor, and physical adsorption deodorization components are easy to desorb at high temperature, leading to VOC rebound. The composite material is integrally formed by hot pressing and melting of a surface layer, an intermediate functional layer and a bottom layer, the intermediate functional layer takes POE resin as a matrix, contains covalently bonded metal ion modified beta-cyclodextrin and surface grafted activated carbon functional units, and is compounded with an intumescent flame-retardant system and nano-montmorillonite; the preparation comprises the steps of pre-modification of functional components, preparation of an intermediate layer master batch and three-layer hot pressing forming. Through a chemical adsorption-chemical fixation synergistic mechanism and a multi-stage carbon formation barrier structure, the application realizes odor grade of less than or equal to 3.0, combustion rate of less than or equal to 80 mm / min, VOC long-term stability without desorption, halogen-free environmental protection, and can be adapted to an existing hot pressing forming production line.

Description

Technical Field

[0001] This invention relates to the technical field, and in particular to a low-odor flame-retardant automotive carpet composite material and its preparation method. Background Technology

[0002] Carpets are one of the interior components with the largest coverage area in passenger vehicles. Their environmental performance and flame retardant safety performance are directly related to the health experience of drivers and passengers and the driving safety of the vehicle. With the continuous upgrading of automotive interior industry standards, mainstream OEMs have increasingly stringent requirements for carpet materials. They generally require that the odor level meet the PV3900 standard ≤3.0, the combustion rate meet the GB8410 standard ≤100mm / min, and the emissions of VOCs such as aldehydes and ketones must meet the limit requirements of the "Guidelines for Air Quality Evaluation in Passenger Cars" and ensure stable performance during long-term use.

[0003] Under the existing technological system, there has always been a difficult technical contradiction to overcome in the synergy between flame retardancy and low odor performance of automotive carpet composite materials.

[0004] Existing flame retardant modification schemes mostly rely on halogenated or phosphorus-based flame retardant systems. While halogenated flame retardants have high flame retardant efficiency, they easily release toxic and harmful fumes during combustion, failing to meet environmental regulations such as RoHS and REACH. Conventional phosphorus-based intumescent flame retardants are more environmentally friendly, but require a high addition amount of 15-20 wt% to meet the flame retardant rating requirements. The introduction of large amounts of flame retardants not only degrades the mechanical properties and processability of the material, but also continuously releases irritating volatile organic compounds such as amines and aldehydes during extrusion, hot pressing, and subsequent use, resulting in an odor rating that generally exceeds 3.5, making it difficult to simultaneously meet the dual requirements of low odor and high flame retardancy.

[0005] To reduce material odor and VOC emissions, existing solutions mostly use porous materials such as activated carbon and molecular sieves as deodorizing components, relying on physical adsorption to trap small VOC molecules. However, physical adsorption is a reversible process and is significantly affected by temperature fluctuations in the vehicle's interior environment. In summer, the temperature inside a closed vehicle can rise to over 70°C, and vehicles undergo repeated hot and cold cycles during long-term use. Previously adsorbed volatile substances are prone to desorption and re-release into the vehicle's interior, forming secondary pollution. This leads to VOC rebound and an increase in odor levels, making it impossible to achieve a long-term, stable low-odor effect.

[0006] To balance flame retardancy and deodorization, some existing technologies employ a layered, laminated structure of "flame retardant layer + deodorization layer." This avoids performance conflicts between components through functional zoning. However, this type of structure requires adhesives to bond the layers together. Adhesives themselves are a significant source of VOCs in the vehicle, which adds to the difficulty of odor control. Furthermore, during the hot pressing and long-term use of automotive carpets under alternating high and low temperatures, bonding failures and peeling can easily occur at the layered interfaces, affecting the structural stability and lifespan of the material.

[0007] In addition, existing formulations focus more on the odor and flame retardancy of the finished product, and do not adequately control the small molecules of aldehydes and ketones generated by the thermal oxidation degradation of resin during processing. Polyolefin substrates such as POE are prone to thermal oxidation degradation during high-temperature extrusion and hot pressing processes, generating low-molecular-weight aldehydes and ketones, which are also important endogenous sources of material odor. It is difficult to completely eliminate such degradation products by relying solely on back-end adsorption treatment, resulting in limited overall deodorization efficiency.

[0008] Therefore, this application proposes a low-odor flame-retardant automotive carpet composite material and its preparation method. Summary of the Invention

[0009] One objective of this invention is to propose a low-odor flame-retardant automotive carpet composite material and its preparation method. This invention can solve the industry technical problem that it is difficult to achieve both flame-retardant performance and low-odor performance in existing automotive carpet composite materials. In response to the technical defects of traditional solutions, such as high-temperature desorption rebound of physical adsorption deodorizing components, easy deterioration of material odor by high addition of flame retardants, and easy introduction of additional VOCs due to the dependence of multi-layer functional structures on adhesive bonding, this invention achieves a synergistic improvement of multiple properties through molecular-level modification and chemical bonding design of functional components.

[0010] According to an embodiment of the present invention, a low-odor flame-retardant automotive carpet composite material comprises, from top to bottom, a top layer, an intermediate functional layer, and a bottom layer, wherein the top layer is a PET / PP composite fiber layer and the bottom layer is a PET nonwoven fabric layer;

[0011] The intermediate functional layer comprises the following components by weight: 40-60 parts POE resin, 10-20 parts metal ion modified β-cyclodextrin, 5-15 parts surface-grafted activated carbon, 5-12 parts nano-montmorillonite, 8-15 parts ammonium polyphosphate, 3-8 parts pentaerythritol, 2-6 parts melamine cyanurate, 3-8 parts compatibilizer, and 0.3-0.8 parts antioxidant.

[0012] The metal ion-modified β-cyclodextrin and the surface-grafted activated carbon form a chemical bond structure through covalent bonds, and the two are uniformly dispersed in the resin matrix of the intermediate functional layer.

[0013] Furthermore, the surface layer is made of 60-80 parts by weight of PET fiber and 20-40 parts by weight of PP fiber through opening, carding and web laying. The PP fiber is used as a thermal bonding component, which melts and bonds the PET fiber during hot pressing and forms a molten interface with the resin matrix of the intermediate functional layer.

[0014] Furthermore, the metal ion-modified β-cyclodextrin is obtained by modification with a titanate coupling agent. When β-cyclodextrin is supported, the functional groups of the titanate coupling agent undergo a coordination chelation reaction with the hydroxyl groups on the surface of the β-cyclodextrin molecule. Embedded within the hydrophobic cavity of β-cyclodextrin, the long alkyl chain of the titanate coupling agent forms a physically entangled structure with the molecular chain of β-cyclodextrin.

[0015] Furthermore, the surface-grafted activated carbon is a modified activated carbon powder that has been modified with mercaptosulfonate to introduce carbon-carbon double bonds; the carbon-carbon double bonds on the surface of the modified activated carbon are covalently linked to the metal ion-modified β-cyclodextrin molecules through a free radical grafting polymerization reaction, the original porous adsorption structure of the activated carbon is completely preserved, and the β-cyclodextrin molecules are grafted onto the outer surface and inner wall of the pores of the activated carbon.

[0016] Furthermore, the degree of polymerization of the ammonium polyphosphate is n≥1000, and together with pentaerythritol and melamine cyanurate, it constitutes an intumescent flame retardant system with a matched acid source-carbon source-gas source. The nano-montmorillonite is an organically intercalated modified nanosheet montmorillonite with a sheet thickness of 1-100 nm, and it is in a peeled dispersion state in the resin matrix.

[0017] Furthermore, the POE resin contains 18% to 28% vinyl acetate by mass; the compatibilizer is maleic anhydride-grafted POE with a maleic anhydride grafting rate of 0.8% to 1.5%; and the composite antioxidant is a mixture of hindered phenolic antioxidant 1010 and phosphite antioxidant 168 in a mass ratio of 1:2.

[0018] Furthermore, the bottom layer is a needle-punched or spunbond PET nonwoven fabric with a basis weight of [missing information]. The total thickness of the composite material is 2-5 mm, of which the thickness of the intermediate functional layer is 1-3 mm.

[0019] A method for preparing a low-odor, flame-retardant automotive carpet composite material includes the following steps:

[0020] S1. Functional component pre-modification: Metal ion modified β-cyclodextrin and surface-grafted activated carbon were prepared separately, sealed and dried for later use;

[0021] S2. Preparation of intermediate layer masterbatch: POE resin, surface-grafted activated carbon, metal ion modified β-cyclodextrin, nano-montmorillonite, ammonium polyphosphate, pentaerythritol, melamine cyanurate, compatibilizer and antioxidant are added into a high-speed mixer according to the ratio and mixed evenly. Then, the mixture is fed into a twin-screw extruder for melt blending and extrusion granulation to obtain intermediate layer functional masterbatch.

[0022] S3. Three-layer hot-press composite molding: The bottom layer of PET non-woven fabric, the middle layer of functional masterbatch sheet obtained by casting, and the top layer of PET / PP composite fiber are laid from bottom to top. The layers are then fed into a mold for hot pressing, cooled and shaped, and then punched and trimmed to obtain the finished product.

[0023] Furthermore, the preparation process of metal ion-modified β-cyclodextrin in step S1 is characterized by:

[0024] S11. Add β-cyclodextrin and titanate coupling agent to anhydrous ethanol solvent at a mass ratio of 1:(1~5), stir until completely dispersed, and then heat to 55~65℃ and stir for 1~1.5h.

[0025] After the reaction was completed, the filter cake was subjected to vacuum filtration and dried in a vacuum drying oven at 70-80℃ for 2.5-3.5 h to obtain titanium ion modified β-cyclodextrin.

[0026] S12. Mix activated carbon powder with anhydrous ethanol at a solid-liquid ratio of 1:(10-15) and ultrasonically disperse for 10-20 minutes to form a uniform suspension.

[0027] Sodium 3-mercapto-1-propanesulfonate was added to the suspension, and the temperature was raised to 60-70℃ and stirred for 2-3 hours. After the reaction, the carbon was centrifuged, washed, and vacuum dried to obtain double-bond modified activated carbon.

[0028] Double bond modified activated carbon and titanium ion modified β-cyclodextrin were added to a mixed solution of water and acetonitrile at a mass ratio of 1:(1~2). After stirring and dispersing, azobisisobutyronitrile (AIBN) and dimethyl ethylene glycol acrylate (DMGE) were added as initiators. The mixture was heated to 70~80℃ for precipitation co-distillation polymerization reaction for 3~4 hours.

[0029] After the reaction was completed, the solid product was separated by centrifugation, and after repeated washing with anhydrous ethanol and vacuum drying, surface-grafted activated carbon was obtained.

[0030] Furthermore, the high-speed mixer in step S2 has a rotation speed of 800-1200 rpm, a room temperature mixing time of 8-12 min, and its twin-screw extruder has its temperature in each zone along the feeding direction set sequentially to 140℃, 150℃, 165℃, 175℃, 180℃, 175℃, and 165℃, with a die head temperature of 165-175℃ and a screw rotation speed of 200-300 rpm.

[0031] In step S3, the thickness of the resin sheet extruded by casting is controlled to be 1-3 mm. In the hot pressing process, the mold temperature is 180-210℃. After the mold is closed, it is preheated at a low pressure of 0.5-1 MPa for 1-2 minutes, and then the pressure is gradually increased to 3-5 MPa and held for 3-5 minutes. After the pressure is held, the mold is cooled with water to below 40℃, and the finished product is taken out after the mold is opened.

[0032] The beneficial effects of this invention are:

[0033] This invention uses a covalently bonded functional unit formed by metal ion-modified β-cyclodextrin and surface-grafted activated carbon as its core. On the one hand, it relies on the porous structure of activated carbon to rapidly adsorb and enrich small VOC molecules such as aldehydes, ketones, and amines in the vehicle. Then, through the hydroxyl groups on the surface of β-cyclodextrin molecules, it undergoes an acetalization reaction with the adsorbed and enriched small VOC molecules and forms stable hydrogen bonds, transforming volatile small molecules into high molecular weight stable compounds. This constructs an irreversible deodorization mechanism of physical adsorption enrichment and chemical fixation transformation, fundamentally eliminating the risk of secondary pollution from VOC desorption and rebound under the high temperature environment in the vehicle in summer. It keeps the odor level of the material stably controlled within 3.0 and can still maintain a high VOC removal rate after long-term thermal aging.

[0034] on the other hand, The modified β-cyclodextrin loaded with heat can catalyze intermolecular dehydration and cross-linking reactions during combustion. Combined with the molecular entanglement of titanate long chains and char layer, it forms a dense and stable reinforced char layer. Furthermore, it forms a multi-level synergistic flame retardant network with the acid source dehydration and foaming, gas source dilution and oxygen barrier effect of the intumescent flame retardant system, as well as the sheet-like physical barrier effect of nano-montmorillonite. Under the condition of low total amount of flame retardant added, it can achieve a high flame retardant effect with a burning rate ≤80mm / min, self-extinguishing after flame removal and no dripping, avoiding the problems of increased odor and decreased mechanical properties caused by adding a large amount of flame retardant.

[0035] Meanwhile, the present invention adopts a melt-pressed composite structure of a top layer, an intermediate functional layer and a bottom layer. It utilizes the melt compatibility of the PP fiber in the top layer and the POE resin in the intermediate layer to achieve glue-free interlayer bonding, which reduces the VOC and odor sources from adhesives from the source, and improves the interlayer bonding strength and long-term durability.

[0036] The overall formula contains no halogens and complies with environmental regulations such as RoHS and REACH. The preparation process can be directly adapted to existing automotive carpet hot pressing production lines without additional equipment modification investment, demonstrating significant technological advancements and promising prospects for industrial application. Attached Figure Description

[0037] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0038] Figure 1 This is a schematic diagram of a low-odor flame-retardant automotive carpet composite material proposed in this invention;

[0039] Figure 2 This is a schematic diagram of the preparation method of a low-odor flame-retardant automotive carpet composite material proposed in this invention. Detailed Implementation

[0040] To make the technical means and objectives and effects of the present invention easier to understand, the embodiments of the present invention will be described in detail below with reference to specific illustrations.

[0041] like Figure 1-2 As shown, this invention discloses a low-odor, flame-retardant automotive carpet composite material, comprising a top layer, a middle functional layer, and a bottom layer from top to bottom. The layers are fused together via a hot-pressing process, eliminating the need for additional adhesives and avoiding volatile organic compound pollution introduced by adhesives. The total thickness of the composite material is controlled between 2 and 5 mm, and the thickness and weight can be adjusted according to the interior molding requirements of different car models, adapting to existing hot-pressing molding processes for automotive carpets.

[0042] The surface layer is a PET / PP composite fiber layer, which is made of 60-80 parts by weight of PET fiber and 20-40 parts by weight of PP fiber through opening, carding and web laying processes to make fiber felt.

[0043] PET fiber serves as the skeleton component, providing the surface layer with abrasion resistance, structural strength, and appearance texture, ensuring the carpet surface's anti-pilling performance and service life.

[0044] As a thermal bonding component, PP fiber has a lower melting point than PET fiber. It melts first during the subsequent hot-pressing process, bonding the PET fiber to form a stable surface fiber network on the one hand, and melting and bonding with the resin matrix of the underlying intermediate functional layer on the other hand, forming a strong interlayer interface and avoiding delamination problems during long-term use.

[0045] The bottom layer is a PET nonwoven fabric layer, prepared using needle punching or spunbonding processes, with the basis weight controlled at [value missing]. It mainly serves as a structural support and skeleton shaping function, while also improving the friction performance of the back of the composite material, making it easier to install and fix the carpet on the car floor, and preventing displacement and abnormal noise during vehicle operation.

[0046] The intermediate functional layer is a modified POE resin foam layer, which is the core structure for achieving synergistic performance of low odor and high flame retardancy. It contains the following components by weight:

[0047] 40-60 parts of POE resin, 10-20 parts of metal ion modified β-cyclodextrin, 5-15 parts of surface-grafted activated carbon, 5-12 parts of nano-montmorillonite, 8-15 parts of ammonium polyphosphate, 3-8 parts of pentaerythritol, 2-6 parts of melamine cyanurate, 3-8 parts of compatibilizer, and 0.3-0.8 parts of antioxidant.

[0048] Each functional component is uniformly dispersed in the POE resin matrix. Among them, the metal ion modified β-cyclodextrin and the surface-grafted activated carbon form a chemical bond structure through covalent bonds. The two constitute a synergistic deodorization unit of "adsorption-fixation". At the same time, together with ammonium polyphosphate, pentaerythritol, melamine cyanurate, and nano-montmorillonite, they form a multi-level synergistic flame retardant system, forming a dense and stable barrier carbon layer during combustion.

[0049] Specifically, the metal ion-modified β-cyclodextrin is obtained by modification with a titanate coupling agent. Loaded β-cyclodextrin.

[0050] β-Cyclodextrin molecules contain 21 hydroxyl groups. When heated, they can undergo a dehydration reaction to form ether bonds, which then cross-link and carbonize to form a char layer. However, the char layer formed by pure β-cyclodextrin has a loose structure and is easily dispersed by the combustion gas flow at high temperatures, resulting in limited flame retardant effect.

[0051] After modification with a titanate coupling agent, the functional groups of the titanate undergo a coordination chelation reaction with the hydroxyl groups on the surface of the β-cyclodextrin molecule. It is embedded inside the hydrophobic cavity of β-cyclodextrin to form a stable complex backbone; at the same time, the long alkyl chain of the titanate coupling agent forms a physical entanglement structure with the molecular chain of β-cyclodextrin.

[0052] During the heated combustion process, It can catalyze the dehydration and cross-linking reaction of β-cyclodextrin, accelerate the char formation rate, and improve the density of the char layer; the alkyl long chain will entangle with the generated char layer, playing a role similar to steel reinforcement, significantly improving the structural strength and high temperature stability of the char layer, preventing the char layer from being destroyed by airflow, and thus continuously playing the role of oxygen isolation, heat insulation, and blocking the diffusion of combustible gases.

[0053] Surface-grafted activated carbon is a modified activated carbon powder that has been modified with mercaptosulfonate to introduce carbon-carbon double bonds. Its preparation process involves a free radical grafting polymerization reaction, which causes the carbon-carbon double bonds on the surface of the modified activated carbon to form covalent bonds with metal ion-modified β-cyclodextrin molecules.

[0054] After grafting modification, the original porous adsorption structure of activated carbon is completely preserved, enabling rapid adsorption of volatile organic compounds such as aldehydes and amines in the vehicle interior environment. Simultaneously, the β-cyclodextrin molecules grafted onto the outer surface and inner walls of the pores of the activated carbon can undergo acetalization reactions or form stable hydrogen bonds with the adsorbed and enriched VOC molecules, converting small-molecule volatile substances into high-molecular-weight stable compounds, achieving chemical fixation at the molecular level. This structure completely solves the problem of easy desorption at high temperatures in traditional physical adsorption methods. Even if the temperature inside the vehicle rises above 70°C in summer, or after long-term thermal aging, the fixed VOCs will not be released again, causing secondary pollution, thus achieving long-term stability of VOC emissions.

[0055] Ammonium polyphosphate, pentaerythritol, and melamine cyanurate together constitute an intumescent flame retardant system with a matched acid source, carbon source, and gas source. Among them, ammonium polyphosphate has a degree of polymerization n≥1000 and acts as an acid source. When heated, it decomposes to generate polyphosphoric acid, which catalyzes the dehydration and carbonization of hydroxyl-containing components. Pentaerythritol acts as a carbon source, providing a carbonization framework. Melamine cyanurate acts as a gas source. When heated, it decomposes to release non-combustible gases such as nitrogen and carbon dioxide, which promote the expansion of the carbon layer to form a porous barrier structure.

[0056] Nano-montmorillonite is organically intercalated modified nanosheet montmorillonite with a sheet thickness of 1-100 nm. It is uniformly dispersed in the resin matrix in an exfoliated manner. During combustion, the montmorillonite nanosheets migrate to the material surface with the melt, forming a physical barrier. On the one hand, it blocks the transfer of external heat to the material interior, and on the other hand, it inhibits the boiling effect during the foaming process of the intumescent flame retardant system, making the generated intumescent char layer more uniform and dense, and further improving the flame retardant barrier effect.

[0057] The POE resin contains 18% to 28% vinyl acetate by mass. POE resin in this content range has both good flexibility and filler compatibility, can uniformly support various functional fillers, and at the same time ensure the bending performance and molding adaptability of the composite material, meeting the molding requirements of complex shapes in automotive carpets.

[0058] The compatibilizer is maleic anhydride-grafted POE with a maleic anhydride grafting rate of 0.8% to 1.5%. It can improve the interfacial bonding force between inorganic fillers and POE resin matrix, avoid the material performance degradation caused by filler agglomeration, and improve the mechanical stability and functional uniformity of composite materials.

[0059] The antioxidant is a composite antioxidant made by compounding hindered phenolic antioxidant 1010 and phosphite antioxidant 168 in a mass ratio of 1:2. It can effectively inhibit the thermal oxidative degradation of resin during processing, reduce the generation of small molecule degradation products of aldehydes and ketones, and reduce the odor and VOC emission of materials from the source.

[0060] The preparation method of the above-mentioned low-odor flame-retardant automotive carpet composite material includes three main steps: functional component pre-modification, intermediate layer masterbatch preparation, and three-layer hot-pressing composite molding. The specific steps are as follows:

[0061] S1. First, the functional components are pre-modified and prepared. Metal ion-modified β-cyclodextrin and surface-grafted activated carbon are prepared separately. After preparation, they are sealed, dried and stored for later use.

[0062] The preparation process of metal ion modified β-cyclodextrin is as follows: β-cyclodextrin and titanate coupling agent are added to anhydrous ethanol solvent at a mass ratio of 1:(1~5), and stirred until the material is completely dispersed. Then, the temperature is raised to 55~65℃ and stirred for 1~1.5h to allow the titanate and β-cyclodextrin to fully undergo coordination chelation reaction.

[0063] After the reaction is complete, the mixture is filtered under reduced pressure, the filter cake is collected and placed in a vacuum drying oven and dried at 70-80℃ for 2.5-3.5h to completely remove the solvent and obtain the titanium ion modified β-cyclodextrin product.

[0064] The preparation of surface-grafted activated carbon is carried out in two steps:

[0065] S11. Preparation of double bond modified activated carbon: Activated carbon powder and anhydrous ethanol are mixed at a solid-liquid ratio of 1:(10-15), and ultrasonically dispersed for 10-20 min to form a uniform suspension. Sodium 3-mercapto-1-propanesulfonate is added to the suspension, and the temperature is raised to 60-70℃ and stirred for 2-3 h. After the reaction is completed, the product is centrifuged and washed to remove unreacted reagents. After vacuum drying, double bond modified activated carbon with carbon-carbon double bonds introduced on the surface is obtained.

[0066] S12. Perform graft polymerization reaction. Add double bond modified activated carbon and titanium ion modified β-cyclodextrin to a mixed solution of water and acetonitrile at a mass ratio of 1:(1~2). Stir until the materials are fully dispersed, then add the initiator azobisisobutyronitrile and the crosslinking agent dimethyl ethylene glycol acrylate. Heat to 70~80℃ to carry out precipitation co-distillation polymerization reaction. The reaction time is controlled to be 3~4h. After the reaction is completed, centrifuge to collect the solid product, wash repeatedly with anhydrous ethanol to remove the ungrafted free components, and obtain surface-grafted activated carbon after vacuum drying.

[0067] S2. After completing the pre-modification of functional components, prepare the intermediate layer functional masterbatch.

[0068] Accurately weigh the POE resin, surface-grafted activated carbon, metal ion-modified β-cyclodextrin, nano-montmorillonite, ammonium polyphosphate, pentaerythritol, melamine cyanurate, compatibilizer, and antioxidant according to the formula. Put all materials into a high-speed mixer, control the speed at 800-1200 rpm, and mix at room temperature for 8-12 minutes to ensure that each component is fully dispersed and uniform.

[0069] The uniformly mixed material is fed into a twin-screw extruder for melt blending. The temperatures of each zone of the twin-screw extruder along the feed direction are set sequentially to 140℃, 150℃, 165℃, 175℃, 180℃, 175℃, and 165℃, while the die head temperature is controlled at 165~175℃ and the screw speed is 200~300rpm. After melt blending, the material is extruded through the die head, water-cooled and traction-cut into pellets to obtain intermediate layer functional masterbatch.

[0070] S3. Finally, a three-layer hot-pressing composite molding process is carried out.

[0071] First, lay the bottom PET nonwoven fabric flat on the lower die surface of the hot press mold to ensure no wrinkles or shifts; then, use a casting extrusion machine to make a resin sheet with a thickness of 1-3mm, and evenly cover it on the bottom nonwoven fabric.

[0072] Finally, the PET / PP composite fiber felt is laid on top of the resin sheet, completing the three-layer structure. After mold closing, a stepped hot-pressing process is performed. The mold temperature is preheated to 180-210℃. After mold closing, preheating is first performed at a low pressure of 0.5-1MPa for 1-2 minutes to fully melt the resin sheet and impregnate the upper and lower layers. Then, the pressure is gradually increased to 3-5MPa and held for 3-5 minutes to ensure that each layer is fully melted and bonded, and the functional components are evenly distributed. After the pressure holding is completed, cooling water is introduced into the mold for cooling. After the mold temperature drops below 40℃, the mold is opened, the composite board is removed, and after punching and trimming, the finished automotive carpet composite material is obtained.

[0073] The technical solutions and effects of the present invention will be further illustrated by specific embodiments below, but the scope of protection of the present invention is not limited to the following embodiments.

[0074] Example 1

[0075] The low-odor, flame-retardant automotive carpet composite material of this embodiment consists of a top layer, a middle functional layer, and a bottom layer from top to bottom, with a total thickness of 3 mm, of which the middle functional layer is 1.5 mm thick. The top layer is made of 70 parts by weight of PET fiber and 30 parts by weight of PP fiber through opening, carding, and web laying to form a fiber felt; the bottom layer is needle-punched PET nonwoven fabric with a basis weight of 100 g / m².

[0076] The intermediate functional layer consists of the following components by weight:

[0077] 50 parts of POE resin (VA content 22%), 15 parts of metal ion modified β-cyclodextrin, 10 parts of surface-grafted activated carbon, 8 parts of nano-montmorillonite, 12 parts of ammonium polyphosphate (degree of polymerization n≥1000), 5 parts of pentaerythritol, 4 parts of melamine cyanurate, 5 parts of maleic anhydride-grafted POE, and 0.5 parts of composite antioxidant, wherein the composite antioxidant is composed of antioxidant 1010 and antioxidant 168 in a mass ratio of 1:2.

[0078] This embodiment is prepared according to the aforementioned preparation method, and the specific process parameters are as follows:

[0079] The mass ratio of β-cyclodextrin to titanate coupling agent was 1:3, the modification reaction temperature was 60℃, the reaction time was 1.2h, the vacuum drying temperature was 75℃, and the drying time was 3h; the solid-liquid ratio of activated carbon to anhydrous ethanol was 1:12, ultrasonic dispersion was performed for 15min, the double bond modification reaction temperature was 65℃, and the reaction time was 2.5h; in the grafting reaction, the mass ratio of double bond modified activated carbon to modified β-cyclodextrin was 1:1.5, the reaction temperature was 75℃, and the reaction time was 3.5h; the high-speed mixer speed was 1000rpm, and the mixing time at room temperature was 10min; the temperature of each zone of the twin-screw extruder was executed according to the set value, and the screw speed was 250rpm; the hot pressing molding temperature was 200℃, the low pressure was 0.8MPa preheating for 1.5min, the pressure was increased to 4MPa and held for 4min, and the mold was opened and trimmed after cooling to 35℃ with water.

[0080] The samples prepared in this embodiment were subjected to performance testing. The odor level was evaluated according to the PV3900 standard at 80℃ for 2 hours. The combustion rate was tested according to the GB8410 standard. The removal rate of aldehydes and ketones VOCs was calculated using pure POE substrate of the same thickness as a blank control. The VOC performance after heat aging at 80℃ for 168 hours was also tested. The test results are shown in Table 1.

[0081] Table 1. Test results of composite material performance in Example 1

[0082] Odor rating Level 2.8 PV3900, 80℃×2h Burning rate 72mm / min GB8410 Combustion phenomenon Self-extinguishing upon removal from the flame, with no molten droplets. GB8410 Initial removal rate of aldehydes and ketones VOCs 88% Using pure POE substrate as a blank control VOC removal rate after 80℃ heat aging for 168 hours 87% Tested after 168 hours of constant temperature heat aging at 80℃.

[0083] Example 2

[0084] The low-odor, flame-retardant automotive carpet composite material of this embodiment has a total thickness of 2.5 mm, with the intermediate functional layer having a thickness of 1.2 mm. The top layer is made of 65 parts by weight of PET fiber and 35 parts by weight of PP fiber; the bottom layer is spunbond PET nonwoven fabric with a basis weight of [missing information]. .

[0085] The intermediate functional layer consists of the following components by weight:

[0086] 55 parts of POE resin (VA content 20%), 12 parts of metal ion modified β-cyclodextrin, 8 parts of surface-grafted activated carbon, 6 parts of nano-montmorillonite, 10 parts of ammonium polyphosphate (degree of polymerization n≥1000), 4 parts of pentaerythritol, 3 parts of melamine cyanurate, 4 parts of maleic anhydride-grafted POE, and 0.4 parts of composite antioxidant.

[0087] The preparation process parameters in this embodiment are adjusted as follows:

[0088] The mass ratio of β-cyclodextrin to titanate coupling agent was 1:2. The modification reaction temperature was 58℃, the reaction time was 1 h, the drying temperature was 72℃, and the drying time was 2.8 h. The grafting reaction temperature was 72℃, and the reaction time was 3 h. The high-speed mixer speed was 900 rpm, and the mixing time was 9 min. The twin-screw extruder screw speed was 220 rpm. The hot pressing molding temperature was 190℃, the low pressure was 0.6 MPa for 1 min, the pressure was increased to 3.5 MPa and held for 3.5 min, and the mold was opened after cooling to 38℃. The remaining preparation steps and raw material composition were consistent with those in Example 1.

[0089] The samples prepared in this embodiment were tested for performance according to the same standards, and the test results are shown in Table 2:

[0090] Table 2. Test results of composite material performance in Example 2

[0091] Odor rating Level 2.9 PV3900, 80℃×2h Burning rate 76mm / min GB8410 Combustion phenomenon Self-extinguishing upon removal from the flame, with no molten droplets. GB8410 Initial removal rate of aldehydes and ketones VOCs 86% Using pure POE substrate as a blank control VOC removal rate after 80℃ heat aging for 168 hours 85% Tested after 168 hours of constant temperature heat aging at 80℃.

[0092] Example 3

[0093] The low-odor, flame-retardant automotive carpet composite material of this embodiment has a total thickness of 4 mm, with the intermediate functional layer being 2 mm thick. The surface layer is made of 75 parts by weight of PET fiber and 25 parts by weight of PP fiber; the bottom layer is needle-punched PET nonwoven fabric with a basis weight of [missing information]. .

[0094] The intermediate functional layer consists of the following components by weight:

[0095] 45 parts of POE resin (VA content 25%), 18 parts of metal ion modified β-cyclodextrin, 12 parts of surface-grafted activated carbon, 10 parts of nano-montmorillonite, 14 parts of ammonium polyphosphate (degree of polymerization n≥1000), 7 parts of pentaerythritol, 5 parts of melamine cyanurate, 7 parts of maleic anhydride-grafted POE, and 0.7 parts of composite antioxidant.

[0096] The preparation process parameters in this embodiment are adjusted as follows:

[0097] The mass ratio of β-cyclodextrin to titanate coupling agent was 1:4. The modification reaction temperature was 62℃, the reaction time was 1.5h, the drying temperature was 78℃, and the drying time was 3.2h. The grafting reaction temperature was 78℃, and the reaction time was 4h. The high-speed mixer speed was 1100rpm, and the mixing time was 11min. The twin-screw extruder screw speed was 280rpm. The hot pressing molding temperature was 205℃, the low pressure was 1MPa preheated for 2min, the pressure was increased to 4.5MPa and held for 5min, and the mold was opened after cooling to 32℃. The remaining preparation steps and raw material composition were consistent with those in Example 1.

[0098] The samples prepared in this embodiment were tested for performance according to the same standards, and the test results are shown in Table 3:

[0099] Table 3. Test results of composite material performance in Example 3

[0100] Odor rating Level 2.7 PV3900, 80℃×2h Burning rate 68mm / min GB8410 Combustion phenomenon Self-extinguishing upon removal from the flame, with no molten droplets. GB8410 Initial removal rate of aldehydes and ketones VOCs 90% Using pure POE substrate as a blank control VOC removal rate after 80℃ heat aging for 168 hours 89% Tested after 168 hours of constant temperature heat aging at 80℃.

[0101] The test results from the above embodiments show that the low-odor, flame-retardant automotive carpet composite material prepared by this invention consistently achieves an odor level below 3.0, a burning rate below 80 mm / min, and after 168 hours of high-temperature thermal aging, the VOC removal rate shows no significant decrease, exhibiting no desorption rebound problem common in physical adsorption methods. It can simultaneously meet the requirements of low odor, high flame retardancy, and long-term VOC stability for automotive interior materials. The overall formulation of this solution contains no halogens, complies with RoHS and REACH environmental regulations, and the preparation process is directly compatible with existing automotive carpet hot-pressing production lines without additional equipment modifications, demonstrating significant value for industrial promotion and application.

[0102] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A low-odor, flame-retardant automotive carpet composite material, characterized in that, From top to bottom, it includes a top layer, an intermediate functional layer, and a bottom layer. The top layer is a PET / PP composite fiber layer, and the bottom layer is a PET non-woven fabric layer. The intermediate functional layer comprises the following components by weight: 40-60 parts POE resin, 10-20 parts metal ion modified β-cyclodextrin, 5-15 parts surface-grafted activated carbon, 5-12 parts nano-montmorillonite, 8-15 parts ammonium polyphosphate, 3-8 parts pentaerythritol, 2-6 parts melamine cyanurate, 3-8 parts compatibilizer, and 0.3-0.8 parts antioxidant. The metal ion-modified β-cyclodextrin and the surface-grafted activated carbon form a chemical bond structure through covalent bonds, and the two are uniformly dispersed in the resin matrix of the intermediate functional layer.

2. The low-odor, flame-retardant automotive carpet composite material according to claim 1, characterized in that, The surface layer is made of 60-80 parts by weight of PET fiber and 20-40 parts by weight of PP fiber through opening, carding and web laying. The PP fiber is used as a thermal bonding component, which melts and bonds the PET fiber during hot pressing and forms a molten interface with the resin matrix of the intermediate functional layer.

3. The low-odor, flame-retardant automotive carpet composite material according to claim 1, characterized in that, The metal ion-modified β-cyclodextrin was obtained by modification with a titanate coupling agent. When β-cyclodextrin is supported, the functional groups of the titanate coupling agent undergo a coordination chelation reaction with the hydroxyl groups on the surface of the β-cyclodextrin molecule. Embedded within the hydrophobic cavity of β-cyclodextrin, the long alkyl chain of the titanate coupling agent forms a physically entangled structure with the molecular chain of β-cyclodextrin.

4. The low-odor, flame-retardant automotive carpet composite material according to claim 1, characterized in that, The surface-grafted activated carbon is a modified activated carbon powder that has been modified with mercaptosulfonate to introduce carbon-carbon double bonds. The carbon-carbon double bonds on the surface of the modified activated carbon are covalently linked to the metal ion-modified β-cyclodextrin molecules through a free radical grafting polymerization reaction. The original porous adsorption structure of the activated carbon is completely preserved, and the β-cyclodextrin molecules are grafted onto the outer surface and inner wall of the pores of the activated carbon.

5. The low-odor, flame-retardant automotive carpet composite material according to claim 1, characterized in that, The degree of polymerization of the ammonium polyphosphate is ≥1000. Together with pentaerythritol and melamine cyanurate, it forms an intumescent flame retardant system with a matched acid source, carbon source, and gas source. The nano-montmorillonite is an organically intercalated nanosheet montmorillonite with a sheet thickness of 1-100 nm, which is in a peeled dispersion state in the resin matrix.

6. The low-odor, flame-retardant automotive carpet composite material according to claim 1, characterized in that, The POE resin contains 18% to 28% vinyl acetate by mass; the compatibilizer is maleic anhydride-grafted POE with a maleic anhydride grafting rate of 0.8% to 1.5%; and the composite antioxidant is a mixture of hindered phenolic antioxidant 1010 and phosphite antioxidant 168 in a mass ratio of 1:

2.

7. The low-odor, flame-retardant automotive carpet composite material according to claim 1, characterized in that, The bottom layer is a needle-punched or spunbond PET nonwoven fabric with a basis weight of [missing information]. The total thickness of the composite material is 2-5 mm, of which the thickness of the intermediate functional layer is 1-3 mm.

8. A method for preparing a low-odor, flame-retardant automotive carpet composite material according to any one of claims 1-7, characterized in that, Includes the following steps: S1. Functional component pre-modification: Metal ion modified β-cyclodextrin and surface-grafted activated carbon were prepared separately, sealed and dried for later use; S2. Preparation of intermediate layer masterbatch: POE resin, surface-grafted activated carbon, metal ion modified β-cyclodextrin, nano-montmorillonite, ammonium polyphosphate, pentaerythritol, melamine cyanurate, compatibilizer and antioxidant are added into a high-speed mixer according to the ratio and mixed evenly. Then, the mixture is fed into a twin-screw extruder for melt blending and extrusion granulation to obtain intermediate layer functional masterbatch. S3. Three-layer hot-press composite molding: The bottom layer of PET non-woven fabric, the middle layer of functional masterbatch sheet obtained by casting, and the top layer of PET / PP composite fiber are laid from bottom to top. The layers are then fed into a mold for hot pressing, cooled and shaped, and then punched and trimmed to obtain the finished product.

9. The method for preparing a low-odor flame-retardant automotive carpet composite material according to claim 8, characterized in that, The preparation process of metal ion modified β-cyclodextrin in step S1 is as follows: S11. Add β-cyclodextrin and titanate coupling agent to anhydrous ethanol solvent at a mass ratio of 1:(1~5), stir until completely dispersed, and then heat to 55~65℃ and stir for 1~1.5h. After the reaction was completed, the filter cake was subjected to vacuum filtration and dried in a vacuum drying oven at 70-80℃ for 2.5-3.5 h to obtain titanium ion modified β-cyclodextrin. S12. Mix activated carbon powder with anhydrous ethanol at a solid-liquid ratio of 1:(10-15) and ultrasonically disperse for 10-20 minutes to form a uniform suspension. Sodium 3-mercapto-1-propanesulfonate was added to the suspension, and the temperature was raised to 60-70℃ and stirred for 2-3 hours. After the reaction, the carbon was centrifuged, washed, and vacuum dried to obtain double-bond modified activated carbon. Double bond modified activated carbon and titanium ion modified β-cyclodextrin were added to a mixed solution of water and acetonitrile at a mass ratio of 1:(1~2). After stirring and dispersing, azobisisobutyronitrile (AIBN) and dimethyl ethylene glycol acrylate (DMGE) were added as initiators. The mixture was heated to 70~80℃ for precipitation co-distillation polymerization reaction for 3~4 hours. After the reaction was completed, the solid product was separated by centrifugation, and after repeated washing with anhydrous ethanol and vacuum drying, surface-grafted activated carbon was obtained.

10. The method for preparing a low-odor flame-retardant automotive carpet composite material according to claim 8, characterized in that, In step S2, the high-speed mixer rotates at 800-1200 rpm, and the mixing time at room temperature is 8-12 min. The temperatures of each zone of the twin-screw extruder along the feeding direction are set sequentially to 140℃, 150℃, 165℃, 175℃, 180℃, 175℃, and 165℃, the die head temperature is 165-175℃, and the screw speed is 200-300 rpm. In step S3, the thickness of the resin sheet extruded by casting is controlled to be 1-3 mm. In the hot pressing process, the mold temperature is 180-210℃. After the mold is closed, it is preheated at a low pressure of 0.5-1 MPa for 1-2 minutes, and then the pressure is gradually increased to 3-5 MPa and held for 3-5 minutes. After the pressure is held, the mold is cooled with water to below 40℃, and the finished product is taken out after the mold is opened.

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