Modified automobile cushion material and preparation method thereof

Abstract

The application belongs to the field of automobile cushion and discloses a modified automobile cushion material and a preparation method thereof, which comprises, in terms of weight fractions, 30-40 parts of agricultural straw-based liquid polyol, 60-70 parts of polyether polyol, 95-105 parts of polyisocyanate, 6-9 parts of a compounded flame-retardant system, 2-4 parts of surface-modified straw liquid residue, 1.5-2.5 parts of a composite crosslinking agent, 0.6-0.8 parts of a composite catalytic system, 0.8-1.2 parts of a foam stabilizer, 0.8-1.2 parts of an opening adjusting agent, 1.0-1.5 parts of a chemical foaming agent and 0.3-0.8 parts of a weather-resistant stabilizing aid. The application replaces part of petrochemical raw materials with agricultural straw-based liquid polyol and reuses the liquid residue as a functional filler, and combines a microcapsule-coated compounded flame-retardant system and a surface grafting modification technology, so that the application realizes the high-value utilization of all components of biomass resources, combines the synergistic flame-retardant and interface enhancement technologies and realizes the synergistic unification of environmental protection, flame-retardant safety and mechanical durability of the automobile cushion material.

Description

Technical Field

[0001] This invention relates to the field of automotive seat cushions, and more particularly to a modified automotive seat cushion material and its preparation method. Background Technology

[0002] As part of the automotive interior, car seat cushions directly impact the comfort, safety, and overall quality experience of passengers. With the continuous development of the automotive industry and consumers' increasing demands for driving and riding quality, car seat cushion materials need to possess excellent cushioning and support performance, durable resilience, lightweight properties, and good flame retardant safety. Currently, the mainstream material for car seat cushions is soft polyurethane foam, which is prepared by reacting polyether polyols and isocyanates with catalysts, foaming agents, foam stabilizers, and other additives. Polyurethane foam, with its adjustable density, excellent cushioning and energy absorption, superior resilience, and the ability to customize hardness and density according to different vehicle models, has become the preferred material for automotive seat filling worldwide.

[0003] However, the production of traditional polyurethane foam materials is highly dependent on petrochemical raw materials such as petroleum-based polyols, with almost all of its polyol components derived from petrochemical derivatives such as propylene oxide and ethylene oxide. With the increasing depletion of global petrochemical resources and the deepening implementation of my country's "dual-carbon" strategic goals, this raw material structure, heavily reliant on non-renewable resources, faces increasingly severe sustainability challenges, necessitating the development of alternative bio-based polyol raw materials. Summary of the Invention

[0004] The present invention aims to provide a modified automotive seat cushion material and its preparation method to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A modified automotive seat cushion material, by weight, is prepared from raw materials comprising the following components: 30-40 parts of agricultural straw-based liquefied polyol, 60-70 parts of polyether polyol, 95-105 parts of polyisocyanate, 6-9 parts of compound flame retardant system, 2-4 parts of surface-modified straw liquefaction residue, 1.5-2.5 parts of composite crosslinking agent, 0.6-0.8 parts of composite catalytic system, 0.8-1.2 parts of foam stabilizer, 0.8-1.2 parts of cell opening regulator, 1.0-1.5 parts of chemical foaming agent, and 0.3-0.8 parts of weather-resistant stabilizing agent.

[0006] Preferably, the compound flame retardant system is composed of microcapsule-encapsulated ammonium polyphosphate and alkyl phosphate flame retardant in a mass ratio of (3-4):1; the microcapsule-encapsulated ammonium polyphosphate uses polyurethane prepolymer as the encapsulation material.

[0007] Preferably, the surface-modified straw liquefaction residue is a straw liquefaction byproduct modified by surface grafting with an epoxy silane coupling agent, and its surface has epoxy active groups that can participate in polyurethane polymerization.

[0008] Preferably, the composite crosslinking agent is a compound of diethanolamine and trimethylolpropane in a mass ratio of (1.5-2.5):1; the weather-stabilizing agent is a compound system of hindered phenolic antioxidant and benzotriazole ultraviolet absorber in a mass ratio of (1.5-3):1.

[0009] Preferably, the method for preparing the modified car seat cushion material includes the following steps: S1, the agricultural straw-based liquefied polyol is purified by vacuum treatment to remove light volatile components and reduce acid value; the straw liquefaction residue is surface-grafted with epoxy silane to obtain surface-modified straw liquefaction residue. S2, according to the formula, the refined liquefied polyol, polyether polyol, composite crosslinking agent, composite catalytic system, foam stabilizer, cell opening regulator, chemical foaming agent, compound flame retardant system, surface modified straw liquefaction residue, and weather stabilizing agent are mixed to obtain a uniformly dispersed white material system. S3, add the metered polyisocyanate to the white material and mix evenly, then immediately inject it into the preheated seat cushion molding mold and close the mold, so that the material foams and expands in the closed mold cavity and fills the cavity. After shaping, open the mold. S4, after demolding, the foam is first subjected to segmented atmospheric pressure curing to complete the cross-linking reaction, and then transferred to a vacuum environment for deep devolatilization treatment, finally obtaining the modified car seat cushion material.

[0010] Preferably, the process of surface grafting modification of epoxy silane in step S1 is as follows: after drying and grading the straw liquefaction residue, an epoxy silane coupling agent is added, and the mixture is stirred and reacted under heat preservation, so that silane molecules are chemically bonded and grafted onto the surface of the residue particles.

[0011] Preferably, step S2 adopts a stepwise feeding and dispersion process: first, the refined liquefied polyol, polyether polyol and surface-modified straw liquefaction residue are mixed to obtain a polyol base material with uniformly dispersed filler; then, the remaining additives are added to the polyol base material and mixed evenly to obtain a uniform white material.

[0012] The segmented atmospheric pressure curing in step S4 is a two-stage gradient curing process. The first stage completes the construction of the polyurethane main crosslinking network, and the second stage completes the crosslinking and structural stabilization. The deep devolatilization is a vacuum small molecule removal treatment of the foam under heating.

[0013] The beneficial effects of this technical solution compared to existing technologies are as follows: (1) This invention replaces part of the petrochemical-based polyether polyol with agricultural straw-based liquefied polyol. At the same time, the residue of straw liquefaction by-products is modified by surface grafting with epoxy silane and reused as a functional filler in the polyurethane foaming system. This realizes the full-component high-value utilization of agricultural straw resources from liquefaction products to by-products. The epoxy active groups carried by the surface-modified residue can participate in the polyurethane polymerization reaction and form chemical bonds with the matrix. In the foaming process, it has the dual functions of heterogeneous nucleation to refine the pores and enhance the bonding between the filler and the matrix. With the appropriate cross-linking network constructed by the composite cross-linking agent, the foam meets the requirements for use in car seat cushions in terms of core comfort and durability indicators such as compression set, resilience, and wet heat aging tensile strength retention.

[0014] (2) This invention uses polyurethane prepolymer microcapsules to encapsulate a flame-retardant system of ammonium polyphosphate and alkyl phosphate compound. The microencapsulation treatment significantly improves the interfacial compatibility between ammonium polyphosphate and polyurethane matrix, effectively solving the problems of easy migration and uneven dispersion of traditional flame retardants. At the same time, the microcapsule material and alkyl phosphate produce a phosphorus-nitrogen synergistic flame-retardant effect, enabling the foam to meet the flame-retardant standard requirements of automotive interiors. On this basis, the chemical bonding effect of surface modification residue and the network reinforcement effect of composite crosslinking agent synergistically improve the foam's resistance to damp heat aging, avoiding the technical defects of traditional flame-retardant modification that sacrifice mechanical properties and durability, and achieving a synergistic unity of flame-retardant safety, mechanical strength and long-term reliability of automotive seat cushion materials. Attached Figure Description

[0015] Figure 1 The present invention provides a flowchart of the preparation method; Detailed Implementation The present invention will now be described in further detail with reference to the accompanying drawings and embodiments: The present invention will be further described clearly and in detail below with reference to specific embodiments. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below are generally only some, not all, of the embodiments of the present invention. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0016] Unless otherwise specified, all raw materials used in the embodiments of the present invention are commercially available or obtainable by those skilled in the art; unless otherwise specified, all methods used in the embodiments of the present invention are methods mastered by those skilled in the art.

[0017] The polyether polyol used in these embodiments is EP-330N (hydroxyl value 33-37 mg KOH / g), manufactured by Shandong Lanxing Dongda Chemical Co., Ltd. The polyisocyanate is modified MDI (NCO content 30.5%-32.5%), manufactured by Wanhua Chemical Group Co., Ltd. The foam stabilizer is B8716LF, manufactured by Evonik Industries AG. The cell opening regulator is AK-9901, manufactured by Jiangsu Meiside Chemical Co., Ltd. The chemical foaming agent is deionized water. The hindered phenolic antioxidant is Irganox 1010, and the benzotriazole UV absorber is Tinuvin 328, both purchased from BASF China Ltd.

[0018] The agricultural straw used in this invention is selected from one or more of corn straw, wheat straw, rice straw, sorghum straw, cotton straw, soybean straw, rapeseed straw, and rice straw, with corn straw or wheat straw being preferred. In this embodiment, rice straw is used. The rice straw is dried to a moisture content ≤5%, pulverized to 40-60 mesh, and liquefied at 160°C for 60 min using polyethylene glycol 400 (PEG400) and glycerol (mass ratio 4:1) as liquefaction agents and concentrated sulfuric acid as a catalyst. The liquefaction reaction is carried out under reduced pressure filtration to separate the liquefied liquid and liquefied residue. The liquefied liquid is then subjected to reduced pressure distillation to remove light components, yielding refined agricultural straw-based liquefied polyol with a hydroxyl value of 420-450 mg KOH / g and an acid value ≤2.0 mg KOH / g. The liquefied residue is dried, ground, and graded for later use.

[0019] Ammonium polyphosphate (APP, degree of polymerization ≥1000) was dispersed in cyclohexane, and a stoichiometric amount of polyurethane prepolymer (NCO content 12%~15%) was added. The mixture was stirred and reacted at 60℃ for 4 h. After filtration, washing and drying, microcapsule-encapsulated ammonium polyphosphate was obtained with a core content ≥85%.

[0020] The dried straw liquefaction residue was added to anhydrous ethanol and ultrasonically dispersed for 15 min. Then, γ-glycidyl etheroxypropyltrimethoxysilane (KH-560) was added, with the amount of KH-560 being 3% to 5% of the residue mass. The mixture was stirred at 60°C for 4 h, filtered, washed, and dried to obtain the surface-modified straw liquefaction residue.

[0021] Example 1 A modified automotive seat cushion material, comprising the following components in parts by weight: The compound flame retardant system is composed of microcapsule-encapsulated ammonium polyphosphate and alkyl phosphate flame retardant in a mass ratio of 3.5:1; the composite crosslinking agent is composed of diethanolamine and trimethylolpropane in a mass ratio of 2.0:1; the composite catalytic system is composed of A-33 (triethylenediamine) and Dabco T-9 (stannous octoate) in a mass ratio of 2:1; and the weather stabilizing agent is composed of Irganox 1010 and Tinuvin 328 in a mass ratio of 2:1.

[0022] The preparation method includes the following steps: S1, agricultural straw-based liquefied polyols were purified under reduced pressure, and light volatile components were removed at 80℃ and -0.095 MPa to reduce the acid value to ≤2.0 mg KOH / g; the straw liquefaction residue was modified by surface grafting with epoxy silane, and the dried liquefaction residue was added to anhydrous ethanol, 3.5% KH-560 was added, and the mixture was stirred at 60℃ for 4 h. After filtration, washing and drying, the surface-modified straw liquefaction residue was obtained.

[0023] S2 employs a step-by-step feeding and dispersion process: First, 35 parts of refined liquefied polyol, 65 parts of polyether polyol, and 3 parts of surface-modified straw liquefaction residue are mixed in a high-speed disperser at a speed of 1500 r / min for 15 min to obtain a polyol base material with uniformly dispersed filler; then, 2.0 parts of composite crosslinking agent, 0.7 parts of composite catalytic system, 1.0 part of foam stabilizer, 1.0 part of cell opening regulator, 1.2 parts of chemical foaming agent, 7.5 parts of compound flame retardant system, and 0.5 parts of weather stabilizing agent are added to the polyol base material, and the mixture is stirred and mixed for another 10 min to obtain a uniform white material system.

[0024] S3. Add 100 parts of the metered polyisocyanate to the white material and mix evenly under high-speed stirring (stirring speed 3000 r / min, time 5-8 s). Immediately pour the mixture into a seat cushion molding mold preheated to 45℃ and close the mold. Allow the material to foam and expand in the closed mold cavity and fill the cavity. The foaming time is 120 s. After shaping, open the mold.

[0025] S4. After demolding, the foam is first cured in stages under normal pressure: the first stage is cured at 80℃ for 2 hours to complete the construction of the polyurethane main crosslinking network; the second stage is cured at 100℃ for 4 hours to complete the crosslinking and structural stabilization; then it is transferred to a vacuum environment at 80℃ (-0.095 MPa) for deep devolatilization treatment for 6 hours to finally obtain the modified car seat cushion material.

[0026] Example 2 The difference between this embodiment and Embodiment 1 lies in the weight proportions of the formulation components, as detailed below: In the compound flame retardant system, the mass ratio of microcapsule-encapsulated ammonium polyphosphate to alkyl phosphate flame retardant is 3:1; the mass ratio of diethanolamine to trimethylolpropane in the composite crosslinking agent is 1.5:1. The proportions of the remaining components and the preparation method are the same as in Example 1.

[0027] Example 3 The difference between this embodiment and Embodiment 1 lies in the weight proportions of the formulation components, as detailed below: In the compound flame retardant system, the mass ratio of microcapsule-encapsulated ammonium polyphosphate to alkyl phosphate flame retardant is 4:1; the mass ratio of diethanolamine to trimethylolpropane in the composite crosslinking agent is 2.5:1. The proportions of the remaining components and the preparation method are the same as in Example 1.

[0028] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that no compound flame retardant system is added to the formulation, the amount of other components remains unchanged, and an equal amount of polyether polyol is used to make up the difference.

[0029] The remaining operating steps are the same as in Example 1.

[0030] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that the compound flame retardant system was replaced with an equal amount of unmicroencapsulated ordinary ammonium polyphosphate (APP, degree of polymerization ≥1000), and no alkyl phosphate flame retardant was added.

[0031] The remaining operating steps are the same as in Example 1.

[0032] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that the surface-modified straw liquefaction residue was not modified by epoxy silane coupling agent (the unmodified raw residue was used directly).

[0033] The remaining operating steps are the same as in Example 1.

[0034] Comparative Example 4 The difference between Comparative Example 4 and Example 1 is that no composite crosslinking agent (i.e., no diethanolamine and trimethylolpropane) is added to the formulation, and the amounts of the remaining components remain unchanged, supplemented by an equal amount of polyether polyol.

[0035] The remaining operating steps are the same as in Example 1.

[0036] Performance tests were conducted on the embodiments and comparative examples. The tests included: Foam density: Tested according to GB / T 6343-2009. Compression set: Tested according to GB / T 6669-2008, under 70℃ and 50% compression conditions for 22 h. Resilience: Tested according to GB / T 6670-2008 using the falling ball method. Tensile strength and elongation at break: Tested according to GB / T 6344-2008. Tear strength: Tested according to GB / T 10808-2006. Flame retardancy (limiting oxygen index): Tested according to GB / T 2406.2-2009. Flame retardancy (horizontal burning): Tested according to GB 8410-2006, and the burning rate was recorded. Tensile strength retention rate after damp heat aging: After treating the specimens in a damp heat aging chamber at 70℃ and 95% RH for 168 h, the tensile strength was tested according to GB / T 6344-2008, and the percentage of the tensile strength after aging to the initial tensile strength was calculated. Average pore size: Tested according to GB / T 12811-1991.

[0037] The test results are shown in Tables 1 to 3.

[0038] Table 1. Basic physical properties and cell structure of foam materials in Examples 1-3 and Comparative Examples 1-4 Table 2 Mechanical properties of foam materials in Examples 1-3 and Comparative Examples 1-4 Table 3 Flame retardant and aging resistance properties of foam materials in Examples 1-3 and Comparative Examples 1-4 Results Analysis From Tables 1 to 3, we can see that: (1) Flame retardant performance: The limiting oxygen index of Examples 1-3 reached 25.8%-27.2%, and the burning speed was 48-56 mm / min, which met the flame retardant requirements of GB 8410-2006 for automotive interior materials. Comparative Example 1 did not add any flame retardant, and the oxygen index was only 18.2%, and the burning speed was as high as 98 mm / min, which was seriously insufficient in flame retardant performance. Comparative Example 2 used ordinary APP without microencapsulation, and the oxygen index was only 22.5%, which was lower than that of Example 1 (26.5%). This indicates that the APP without microencapsulation has poor compatibility with the polyurethane matrix, is prone to migration and aggregation, and its surface hydrophilicity reduces the flame retardant durability of the foam in a humid and hot environment; while the present invention uses polyurethane prepolymer encapsulation material, which effectively improves the interfacial compatibility between APP and matrix, and produces a synergistic flame retardant effect with alkyl phosphate.

[0039] (2) Mechanical properties and cell structure: Tensile strength (168 kPa) and tear strength (4.2 N·m) of Example 1 -1 Both the tensile strength and elongation at break (142%) were significantly better than those of Comparative Example 3 (the unmodified residue, with a tensile strength of 145 kPa and a tear strength of 3.6 N·m). -1 Comparative Example 4 (without crosslinking agent, tensile strength 122 kPa, tear strength 3.0 N·m) and Comparative Example 5 (without crosslinking agent, tensile strength 122 kPa, tear strength 3.0 N·m) -1 The average pore size of Comparative Example 3 (368 μm) was also significantly larger than that of Example 1 (312 μm). These results indicate that after graft modification with epoxy silane, the surface of the straw liquefaction residue possesses epoxy active groups that can participate in polyurethane polymerization. These groups can act as heterogeneous nucleation points to refine the pores during foaming, while simultaneously forming chemical bonds with the matrix, significantly enhancing interfacial bonding. The composite crosslinking agent, by constructing a suitable chemical crosslinking network, significantly improves the elasticity and compression resistance of the foam. The compression set (4.8%) and resilience (52%) of Example 1 are far superior to those of Comparative Example 4 (7.2% and 42%, respectively).

[0040] (3) Aging resistance: The tensile strength retention rate of Example 1 after humid heat aging was 89.6%, which was much higher than that of Comparative Example 3 (83.5%) and Comparative Example 4 (78.6%). The reason is that the chemical bonding of the surface modification residue inhibited the peeling of the filler and matrix interface under humid heat conditions; at the same time, the crosslinking network constructed by the composite crosslinking agent effectively restricted the hydrolysis and excessive movement of polyurethane molecular chains under humid heat environment, thus endowing the material with excellent aging resistance.

[0041] (4) Overall effect: Examples 1 to 3 all showed good overall performance within the preferred ratio range. Among them, Example 3 had the best flame retardant performance and mechanical strength due to the highest content of flame retardant and crosslinking agent, but its density was slightly higher. Example 2 had a slightly weaker cost advantage due to the lower content of bio-based polyol, but still maintained good performance. Example 1 was the best balance point. Comparative Examples 1 to 4 verified the indispensability of each key feature in the technical solution of the present invention from four dimensions: flame retardant synergy, necessity of microcapsules, necessity of modification, and necessity of crosslinking.

[0042] The above are merely preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be considered as limitations on the present invention, and the scope of protection of the present invention should be determined by the scope defined in the claims. For those skilled in the art, several improvements and modifications can be made without departing from the spirit and scope of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

[0043] The above descriptions are merely embodiments of the present invention, and common knowledge such as specific technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A modified car seat cushion material, characterized in that, By weight, it is prepared from raw materials including the following components: 30-40 parts of agricultural straw-based liquefied polyol, 60-70 parts of polyether polyol, 95-105 parts of polyisocyanate, 6-9 parts of compound flame retardant system, 2-4 parts of surface-modified straw liquefaction residue, 1.5-2.5 parts of composite crosslinking agent, 0.6-0.8 parts of composite catalytic system, 0.8-1.2 parts of foam stabilizer, 0.8-1.2 parts of cell opening regulator, 1.0-1.5 parts of chemical foaming agent, and 0.3-0.8 parts of weather-resistant stabilizing agent.

2. The modified car seat cushion material according to claim 1, characterized in that, The compound flame retardant system is composed of microcapsule-encapsulated ammonium polyphosphate and alkyl phosphate flame retardant in a mass ratio of (3-4):1; the microcapsule-encapsulated ammonium polyphosphate uses polyurethane prepolymer as the encapsulation material.

3. The modified car seat cushion material according to claim 1, characterized in that, The surface-modified straw liquefaction residue is a straw liquefaction byproduct modified by surface grafting with an epoxy silane coupling agent, and its surface has epoxy active groups that can participate in polyurethane polymerization.

4. The modified car seat cushion material according to claim 1, characterized in that, The composite crosslinking agent is a compound of diethanolamine and trimethylolpropane in a mass ratio of (1.5-2.5):1; the weather-stabilizing agent is a compound system of hindered phenolic antioxidant and benzotriazole ultraviolet absorber in a mass ratio of (1.5-3):

1.

5. A method for preparing a modified automotive seat cushion material as described in any one of claims 1-4, characterized in that, Includes the following steps: S1, the agricultural straw-based liquefied polyol is purified by vacuum treatment to remove light volatile components and reduce acid value; the straw liquefaction residue is surface-grafted with epoxy silane to obtain surface-modified straw liquefaction residue. S2, according to the formula, the refined liquefied polyol, polyether polyol, composite crosslinking agent, composite catalytic system, foam stabilizer, cell opening regulator, chemical foaming agent, compound flame retardant system, surface modified straw liquefaction residue, and weather stabilizing agent are mixed to obtain a uniformly dispersed white material system. S3, add the metered polyisocyanate to the white material and mix evenly, then immediately inject it into the preheated seat cushion molding mold and close the mold, so that the material foams and expands in the closed mold cavity and fills the cavity. After shaping, open the mold. S4, after demolding, the foam is first subjected to segmented atmospheric pressure curing to complete the cross-linking reaction, and then transferred to a vacuum environment for deep devolatilization treatment, finally obtaining the modified car seat cushion material.

6. The method for preparing a modified car seat cushion material according to claim 5, characterized in that, The process of surface grafting modification of epoxy silane in step S1 is as follows: after drying and grading the straw liquefaction residue, epoxy silane coupling agent is added, and the reaction is stirred under heat preservation, so that silane molecules are chemically bonded and loaded onto the surface of the residue particles.

7. The method for preparing a modified automotive seat cushion material according to claim 5, characterized in that, Step S2 adopts a step-by-step feeding and dispersion process: first, the refined liquefied polyol, polyether polyol and surface-modified straw liquefaction residue are mixed to obtain a polyol base material with uniformly dispersed filler; then, the remaining additives are added to the polyol base material and mixed evenly to obtain a uniform white material.

8. The method for preparing a modified car seat cushion material according to claim 5, characterized in that, The segmented atmospheric pressure curing in step S4 is a two-stage gradient curing process. The first stage completes the construction of the polyurethane main crosslinking network, and the second stage completes the crosslinking and structural stabilization. The deep devolatilization is a vacuum small molecule removal treatment of the foam under heating.

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