DPU waste-containing modified rubber runway composite material and preparation method thereof

Abstract

The invention relates to the technical field of solid waste recycling, in particular to a DPU waste-containing modified rubber runway composite material and a preparation method thereof, and the preparation method comprises the following steps: step (1) pretreatment of DPU waste; (2) preparing surface modified DPU waste particles; (3) carrying out first-time internal mixing to obtain first-time internal mixed rubber; (4) rolling a sheet; (5) carrying out sheet plasma treatment; (6) chopping the slices subjected to plasma treatment to prepare modified rubber particles; (7) carrying out secondary banburying to obtain secondary banburying rubber; and (8) carrying out mould pressing vulcanization on the secondary internal mixed rubber to prepare the modified rubber track composite material containing the DPU waste. According to the scheme, through multiple means of silane coupling agent surface modification, aerogel adding, plasma treatment and the like, the activity and dispersity of the DPU waste are improved, the mechanical property and durability of the composite material are optimized, and therefore efficient resource utilization of the DPU waste is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of solid waste recycling, and in particular to a modified rubber track composite material containing DPU waste and a preparation method thereof. Background Art

[0002] With increasing environmental awareness and demand for resource reuse, the application of waste materials in the preparation of high-performance composite materials has become a research hotspot. Due to its stable chemical properties and poor reactivity, DPU (diphenylmethane diisocyanate) waste faces problems such as poor compatibility with matrix materials and poor dispersibility during direct recycling, limiting its application in high-performance composite materials such as rubber tracks. Therefore, developing a method to effectively activate DPU waste and use it in the preparation of modified rubber track composites is of great significance.

[0003] CN116178814B discloses an environmentally friendly plastic track, comprising a top plastic layer and a bottom base layer bonded together. The top plastic layer comprises the following raw materials by weight: 20-50 parts pure MDI, 20-50 parts polyol-modified MDI, 120-360 parts waste rubber powder, 10-20 parts carbon black, 20-40 parts polyether polyol, and 10-20 parts polyacrylamide; the bottom base layer comprises the following raw materials by weight: 200-400 parts ABS waste powder, 100-180 parts thermoplastic elastomer, 20-50 parts glass fiber, and 30-60 parts water-based polyurethane adhesive. The thickness ratio of the top plastic layer to the bottom base layer is 1:2-4. CN110883068B discloses a method for plasticizing solid waste, which crushes the solid waste and mixes it with a plasticizer to produce a plasticized powder material that can be used in fields such as plastic tracks. However, the plasticizer used in this technical solution primarily targets the surface modification of ordinary solid waste, failing to fully consider the specific chemical properties of DPU waste. This may affect its dispersion and interfacial bonding within the composite material. Furthermore, this method leaves room for improvement in optimizing the mechanical properties and durability of the composite material, making it difficult to fully meet the stringent strength, elasticity, and aging resistance requirements of high-performance rubber tracks.

[0004] The above problems indicate that the existing waste material recycling technology has certain limitations in treating DPU waste, especially in terms of surface activation, dispersion improvement and interface bonding with the rubber matrix of DPU waste, which need further optimization. Summary of the Invention

[0005] In order to achieve the above objectives, the present invention provides a modified rubber track composite material containing DPU waste and a preparation method thereof. Through multiple means such as surface modification with a silane coupling agent, aerogel addition and plasma treatment, the activity and dispersibility of the DPU waste are improved, and the mechanical properties and durability of the composite material are optimized, thereby realizing efficient resource utilization of DPU waste.

[0006] The present invention discloses a modified rubber track composite material containing DPU waste and a preparation method thereof. The composite material uses DPU waste as one of the core raw materials and is functionalized by multiple technical means such as surface modification with a silane coupling agent, addition of aerogel, and plasma treatment. After the above-mentioned process treatment, the mass fraction of DPU waste in the composite material is 5-20%, the mass fraction of polyurethane prepolymer is 10-25%, the mass fraction of rubber matrix is ​​40-60%, and the mass fraction of aerogel is 1-5%. The present invention belongs to the field of high-performance composite material technology and aims to solve the problems of insufficient dispersibility and weak interfacial bonding caused by DPU waste in the prior art due to its stable chemical properties and poor activity, while improving the mechanical properties and durability of the composite material to meet the strict requirements of plastic tracks for strength, elasticity, and aging resistance.

[0007] To solve the above problems, the present invention provides a modified rubber track composite material containing DPU waste and a preparation method thereof. The method achieves efficient activation and functionalization of DPU waste through multiple technical means, significantly improves its dispersibility and interfacial compatibility in the composite material, and optimizes the overall performance of the composite material.

[0008] To achieve the above object, the present invention further discloses a preparation process of the modified rubber track composite material containing DPU waste, comprising the following steps:

[0009] Step (1): drying the DPU waste to a moisture content of ≤0.3%, and grinding the DPU waste to a particle size of 10-100 μm to obtain DPU waste particles;

[0010] Step (2): performing surface modification treatment on the DPU waste particles, mixing the DPU waste particles with a silane coupling agent in a mass ratio of 100:1-3, heating to 60-80° C. for reaction for 1-2 hours, filtering and drying to obtain surface-modified DPU waste particles;

[0011] Step (3): mixing the polyurethane prepolymer modified rubber particles and the surface modified DPU waste particles in a mass ratio of 7:1-3:1, adding 1-5 parts of a vulcanizing agent, 0.5-3 parts of an accelerator, 0.5-2 parts of an antioxidant, 1-4 parts of a plasticizer, and 10-30 parts of a filler, and performing a first banburying at a banburying temperature of 80-100° C. for 5-10 minutes to obtain a first banburying rubber;

[0012] Step (4): rolling the first internal mixing rubber into a sheet with a thickness of 1-3 mm;

[0013] Step (5): Plasma treatment is performed on the front and back surfaces of the wafer at a power of 50-100 W for 10-20 seconds using an argon / oxygen mixed gas with a volume ratio of 1-3:1 and a pressure of 10-50 Pa.

[0014] Step (6): chopping the plasma-treated flakes into particles with a diameter of 2-5 mm to obtain modified rubber particles;

[0015] Step (7): mixing the modified rubber particles with 1-3 parts of a vulcanizing agent, 0.3-1.5 parts of an accelerator, 0.3-1 parts of an antioxidant, and 1-5 parts of an aerogel, and performing secondary mixing at a temperature of 70-90° C. for 3-8 minutes to obtain a secondary mixed rubber;

[0016] Step (8): molding the secondary internal compound rubber at 150-180° C. for a vulcanization time of 10-20 min to obtain a modified rubber track composite material containing DPU waste.

[0017] The modified rubber track composite material containing DPU waste disclosed in the present invention has obvious distinguishing features compared with the prior art. In the prior art, DPU waste faces the problems of poor dispersibility and weak interfacial bonding during direct recycling due to its chemical inertness, which limits its application in high-performance composite materials. The present invention, by introducing silane coupling agent surface modification technology, changes the surface chemical properties of DPU waste particles, forms active functional groups on its surface, thereby enhancing the interfacial bonding with the rubber matrix. In addition, the present invention also reduces the surface contact angle of the sheet through plasma treatment, and further improves the surface wettability and interfacial compatibility of the composite material after treatment, significantly improving the dispersibility and interfacial bonding performance of the material. At the same time, the addition of aerogel not only improves the mechanical properties of the composite material, but also gives it excellent thermal insulation and anti-aging properties.

[0018] Preferably, in step (1), the DPU waste is industrial waste of 4,4'-diphenylmethane diisocyanate or 2,4'-diphenylmethane diisocyanate, and the drying is performed by vacuum drying at a temperature of 50-70°C for 2-4 hours. Vacuum drying can effectively remove trace moisture from the DPU waste, thereby preventing the influence of moisture on material properties during subsequent processing.

[0019] Preferably, in step (2), the silane coupling agent is KH-550 or KH-560. The silane coupling agent is selected based on the fact that its molecular structure contains active groups that can chemically react with the surface of the DPU waste, and also contains functional groups that can form a good bond with the rubber matrix, thereby achieving interface strengthening between the DPU waste and the rubber matrix.

[0020] Preferably, in step (3), the rubber matrix is ​​at least one of styrene-butadiene rubber (SBR), butadiene rubber (BR), or natural rubber (NR). When the rubber matrix is ​​a compound of styrene-butadiene rubber and butadiene rubber, the mass ratio of SBR to BR is 2-4:1. This compounding method can take into account the strength and elasticity of the rubber material and meet the requirements of high-performance rubber runways.

[0021] Preferably, in step (3), the filler is at least one of carbon black, white carbon black, clay, or calcium carbonate; and the plasticizer is at least one of naphthenic oil, liquid paraffin, or dioctyl phthalate. The selection of filler and plasticizer is adjusted according to the specific performance requirements of the composite material to achieve optimal overall performance.

[0022] Preferably, in step (3), the vulcanizing agent is sulfur or dicumyl peroxide (DCP); when the vulcanizing agent is sulfur, the accelerator is at least one of cyclohexylthiophthalimide, 2,2'-dibenzothiazole disulfide, or tetramethylthiuram disulfide; when the vulcanizing agent is dicumyl oxide, the accelerator is at least one of triallyl isocyanurate or triallyl cyanurate. The choice of vulcanization system directly affects the crosslinking density and mechanical properties of the composite material.

[0023] Preferably, in step (5), the gas volume ratio of the plasma treatment is argon:oxygen=2:1, and the treatment pressure is 20-40 Pa. Plasma treatment bombards the material surface with high-energy particles to generate oxygen-containing functional groups, thereby improving the surface wettability and interfacial bonding properties of the material.

[0024] Preferably, in step (7), the aerogel is a silica aerogel having a particle size of 5-20 μm. When the aerogel is a silica aerogel, its surface is modified with a silane coupling agent KH-560, wherein the modification method comprises mixing aerogel particles with KH-560 in a mass ratio of 100:0.5-2, heating to 80-100°C for reaction for 2-3 hours, filtering, and drying. The addition of aerogel not only improves the mechanical properties of the composite material, but also imparts it with excellent thermal insulation and anti-aging properties.

[0025] Preferably, in step (8), the compression molding temperature is 150-180°C and the vulcanization time is 10-20 minutes. The selection of the compression molding temperature and time is based on the crosslinking density and vulcanization degree requirements of the composite material to ensure that the final product has excellent mechanical properties and durability.

[0026] The core goal of this technical solution is to achieve high-value recycling of DPU waste while giving the plastic track composite material lightweight, high elasticity and functional properties. Its success mechanism relies on the precise coordination of component design and multi-stage process:

[0027] First, the pretreatment and surface modification of DPU waste lay the foundation for compatibility. Through deep drying (moisture ≤ 0.3%) and fine grinding (10-100μm), the DPU waste obtains a homogeneous physical form. The silane coupling agent (KH-550 / KH-560) reacts with its surface active groups at 60-80°C to form an organic long-chain coating. This step significantly improves the interfacial bonding between the DPU particles and the subsequent rubber matrix, avoiding phase separation due to polarity differences and ensuring that the waste becomes an effective reinforcing phase rather than a source of defects.

[0028] Secondly, the polyurethane prepolymer acts as a reactive compatibilizer. Its isocyanate groups graft or crosslink with rubber chains (styrene-butadiene / butadiene / natural rubber) during the blending process, forming an interpenetrating polymer network (IPN). This structure is strengthened during the first mixing (80-100°C): vulcanizers and accelerators trigger rubber crosslinking, fillers (carbon black / silica) provide reinforcement, plasticizers (naphthenic oil / DOP, etc.) adjust processing fluidity, and antioxidants embed into the network to resist thermal oxidative aging. At this point, the surface-modified DPU particles are evenly dispersed in this dynamic network, achieving the initial structural integration of the waste material.

[0029] Plasma treatment breaks through the interface bottleneck of secondary composites through surface activation. After the primary internal compound is rolled into thin sheets (1-3mm), an argon-oxygen mixture excites a highly active plasma at low pressure, bombarding the material surface to produce etching and free radicals. This process introduces oxygen-containing polar groups (carboxyl, hydroxyl, etc.), which reduces the surface contact angle and significantly improves hydrophilicity. The subsequent chopping (2-5mm) operation exposes the newly active surface, creating key conditions for the uniform dispersion and strong bonding of the aerogel.

[0030] Finally, the low-temperature compounding of aerogels achieves functional enhancement. Plasma-activated particles are compounded with aerogels (silica aerogel / polyurethane aerogel, 5-20μm) in a secondary mixing process (70-90°C). The process temperature and time (3-8min) are optimized to protect the aerogel nanoporous structure. After the aerogel surface is pre-modified with KH-560, its silanol groups form hydrogen bonds or covalent bonds with the oxygen-containing groups generated by plasma activation to achieve nano-scale dispersion. The introduction of aerogel not only significantly reduces the density of the material, but its three-dimensional network more effectively blocks heat conduction and sound wave propagation. At the same time, the secondary cross-linking of a small amount of vulcanizing agent and accelerator further stabilizes the overall structure, and finally a runway composite material with high elasticity, durability and functional properties is formed in the compression vulcanization (150-180°C).

[0031] Compared with the prior art, the present invention has the following advantages:

[0032] 1. The present invention significantly improves the dispersibility and interfacial bonding strength of DPU waste through multiple technical means such as surface modification with silane coupling agents, addition of aerogels, and plasma treatment, thus solving the problems of poor dispersibility and weak interfacial bonding strength of DPU waste in the prior art due to its chemical inertness.

[0033] 2. The addition of aerogel not only improves the mechanical properties of the composite material, but also gives it excellent thermal insulation and aging resistance, meeting the strict requirements of high-performance rubber tracks for material strength, elasticity, and aging resistance.

[0034] 3. The process of the present invention is simple, the raw materials are widely available, and it can adapt to large-scale production, providing a new path for the resource utilization of DPU waste. DETAILED DESCRIPTION

[0035] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0036] Overall embodiment

[0037] A method for preparing a modified rubber track composite material containing DPU waste comprises the following steps:

[0038] Step (1) drying the DPU waste to a moisture content of ≤0.3%, and then grinding the DPU waste to a particle size of 10-100 μm to obtain DPU waste particles; in step (1), the DPU waste is industrial waste of 4,4'-diphenylmethane diisocyanate (MDI) or 2,4'-diphenylmethane diisocyanate (2,4'-MDI), and the drying is performed by vacuum drying at a temperature of 50-70° C. for 2-4 hours;

[0039] Step (2) performing surface modification treatment on the DPU waste particles: mixing the DPU waste particles with a silane coupling agent (KH-550 or KH-560) in a mass ratio of 100:1-3, heating to 60-80° C. for reaction for 1-2 hours, filtering and drying to obtain surface-modified DPU waste particles;

[0040] Step (3) polyurethane prepolymer modified rubber particles and surface modified DPU waste particles are mixed in a mass ratio of 3-7:1, and based on the total mass after mixing as 100 mass parts, 1-5 mass parts of vulcanizing agent, 0.5-3 mass parts of accelerator, 0.5-2 mass parts of antioxidant, 1-4 mass parts of plasticizer, and 10-30 mass parts of filler are added, and the first banburying is performed at a banburying temperature of 80-100°C and a time of 5-10min to obtain the first banburying rubber; the rubber matrix is ​​a compound of styrene-butadiene rubber (SBR) and butadiene rubber (BR), and the mass ratio of SBR to BR is 2-4:1; the reaction temperature of the polyurethane prepolymer is 60-80°C, and the reaction time is 2-3h; the filler is at least one of carbon black, white carbon black, clay or calcium carbonate; the plasticizer is cyclohexane oil , liquid paraffin or dioctyl phthalate (DOP); the vulcanizing agent is sulfur or diisopropyl benzene peroxide (DCP); when the vulcanizing agent is sulfur, the accelerator is at least one of CZ (cyclohexylthiophthalimide), DM (2,2'-dibenzothiazole disulfide) or TMTD (tetramethylthiuram disulfide); when the vulcanizing agent is DCP, the accelerator is at least one of TAC (triallyl isocyanurate) or TAIC (triallyl cyanurate); the antioxidant is at least one of 4010NA (N-isopropyl-N'-phenyl-p-phenylenediamine), RD (2,2,4-trimethyl-1,2-dihydroquinoline polymer) or 4020 (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine);

[0041] Step (4) rolling the first mixed rubber into a sheet with a thickness of 1-3 mm;

[0042] Step (5) plasma treatment is performed on the front and back sides of the wafer at a power of 50-100 W for 10-20 seconds using an argon / oxygen mixture (volume ratio 1-3:1) at a pressure of 10-50 Pa.

[0043] Step (6) chopping the plasma-treated flakes into particles of 2-5 mm to obtain modified rubber particles;

[0044] Step (7) is to add 1-3 parts by mass of a vulcanizing agent, 0.3-1.5 parts by mass of an accelerator, 0.3-1 parts by mass of an antioxidant, and 1-5 parts by mass of an aerogel to 100 parts by mass of the modified rubber particles, and perform secondary banburying at a banburying temperature of 70-90° C. for 3-8 minutes to obtain a secondary banburying rubber; the aerogel is a silica aerogel whose surface is modified with a silane coupling agent (KH-560), and the modification method is: mixing the aerogel particles and KH-560 in a mass ratio of 100:0.5-2, heating to 80-100° C. for reaction for 2-3 hours, filtering and drying; when the vulcanizing agent is sulfur, the amount of the accelerator is 0.3-1.5 parts by mass; when the vulcanizing agent is DCP, the amount of the accelerator is 0.3-1 parts by mass; the amount of the antioxidant is 0.3-1 parts by mass; and the amount of the aerogel is 1-5 parts by mass;

[0045] Step (8) vulcanizing the secondary rubber mixture at 150-180° C. for 10-20 min to obtain a modified rubber track composite material containing DPU waste;

[0046] The polyurethane prepolymer is prepared by reacting DPU with polyether polyol (molecular weight 2000-3000) in a mass ratio of 1:1-1:3, at a reaction temperature of 60-80°C for 2-3 hours, and the -NCO content in the prepolymer is 2-5wt%; the rubber matrix is ​​at least one of styrene-butadiene rubber (SBR), butadiene rubber (BR) or natural rubber (NR); and the aerogel is silica aerogel with a particle size of 5-20 μm.

[0047] Preparation of polyurethane prepolymer modified rubber particles: 3-7 parts of rubber matrix and 1 part of polyurethane prepolymer are added to an internal mixer, and shear mixed at 80-100°C and 20-30 rpm for 5-8 minutes. Antioxidant 4020 is added at 0.5-1% by weight of the rubber matrix, and plasticizer naphthenic oil is added at 1-2% by weight of the rubber matrix to improve stability. After blending, the material is discharged to a flat vulcanizer, and sheeted at a pressure of 5-10 MPa and a temperature of 90-100°C for 3-5 minutes to form a uniform sheet. After naturally cooling to room temperature, the sheet is diced in a grinder to obtain polyurethane prepolymer modified rubber particles.

[0048] Example 1

[0049] A method for preparing a modified rubber track composite material containing DPU waste comprises the following steps:

[0050] Step (1) drying the DPU waste to a moisture content of ≤0.3% and grinding the DPU waste to a particle size of 10 μm to obtain DPU waste particles; the DPU waste in step (1) is industrial waste of 4,4'-diphenylmethane diisocyanate, and the drying is performed by vacuum drying at a temperature of 50° C. for 4 hours;

[0051] Step (2) performing surface modification treatment on the DPU waste particles: mixing the DPU waste particles with a silane coupling agent KH-550 at a mass ratio of 100:1, heating to 60° C. and reacting for 2 h, filtering and drying to obtain surface-modified DPU waste particles;

[0052] Step (3) The polyurethane prepolymer modified rubber particles and the surface modified DPU waste particles are mixed in a mass ratio of 7:1, and the total mass after mixing is 100 parts by mass, 1 part by mass of sulfur as a vulcanizing agent, 0.5 part by mass of accelerator CZ, 0.5 part by mass of antioxidant 4010NA, 1 part by mass of plasticizer naphthenic oil, and 10 parts by mass of filler carbon black are added, and the first banburying is performed at a banburying temperature of 80°C and a time of 10 minutes to obtain a first banburying rubber; the rubber matrix is ​​a compound of styrene-butadiene rubber and butadiene rubber, and the mass ratio of SBR to BR is 2:1; the reaction temperature of the polyurethane prepolymer is 60°C and the reaction time is 3 hours;

[0053] Step (4) rolling the first mixed rubber into a sheet with a thickness of 1 mm;

[0054] Step (5) plasma treatment is performed on the front and back of the wafer at a power of 50 W for 20 seconds using an argon / oxygen mixed gas with a volume ratio of 1:1 and a pressure of 50 Pa;

[0055] Step (6) chopping the plasma-treated flakes into particles of 2 mm to obtain modified rubber particles;

[0056] Step (7) Based on the mass of the modified rubber particles as 100 parts by mass, 1 part by mass of sulfur as a vulcanizing agent, 0.3 part by mass of accelerator CZ, 0.3 part by mass of antioxidant 4010NA, and 1 part by mass of aerogel are added, and secondary mixing is performed at a mixing temperature of 70°C for 8 minutes to obtain a secondary mixed rubber; the aerogel is a silica aerogel whose surface is modified with a silane coupling agent KH-560, and the modification method is: mixing the aerogel particles and KH-560 in a mass ratio of 100:0.5, heating to 80°C for reaction for 3 hours, filtering and drying;

[0057] Step (8) vulcanizing the secondary mixed rubber at 150° C. for 20 min to obtain a modified rubber track composite material containing DPU waste;

[0058] The polyurethane prepolymer is prepared by reacting DPU with a polyether polyol having a molecular weight of 2000 in a mass ratio of 1:1, at a reaction temperature of 60°C for 3 hours, and the -NCO content in the prepolymer is 2 wt%. The aerogel is a silica aerogel with a particle size of 5 μm.

[0059] Preparation of polyurethane prepolymer modified rubber particles: 4 parts of a mixture of styrene-butadiene rubber and butadiene rubber (SBR:BR=2:1) ​​and 1 part of a polyurethane prepolymer (DPU:polyether polyol=1:1, molecular weight 2000) are added to an internal mixer, shear mixed at 80°C and 25 rpm for 6 minutes, and 0.7% of the weight of the rubber matrix by weight of an antioxidant 4020 and 1.2% of the weight of the rubber matrix by weight of a plasticizer cyclohexane oil are added; after blending, the material is unloaded to a flat vulcanizer, pressed at a pressure of 6 MPa and a temperature of 95°C for 4 minutes to form a uniform sheet, which is naturally cooled to room temperature and then granulated by a crusher to obtain polyurethane prepolymer modified rubber particles.

[0060] Example 2

[0061] A method for preparing a modified rubber track composite material containing DPU waste comprises the following steps:

[0062] Step (1) drying the DPU waste to a moisture content of ≤0.3% and grinding the DPU waste to a particle size of 50 μm to obtain DPU waste particles; the DPU waste in step (1) is industrial waste of 2,4'-diphenylmethane diisocyanate, and the drying is performed by vacuum drying at a temperature of 60° C. for 3 hours;

[0063] Step (2) performing surface modification treatment on the DPU waste particles: mixing the DPU waste particles with a silane coupling agent KH-560 in a mass ratio of 100:2, heating to 70° C. and reacting for 1.5 h, filtering and drying to obtain surface-modified DPU waste particles;

[0064] Step (3) The polyurethane prepolymer modified rubber particles and the surface modified DPU waste particles are mixed in a mass ratio of 5:1, and the total mass after mixing is 100 mass parts, and 3 mass parts of vulcanizing agent DCP, 1.5 mass parts of accelerator TAC, 1 mass part of antioxidant RD, 2.5 mass parts of plasticizer liquid paraffin, and 20 mass parts of filler white carbon black are added, and the first banburying is carried out at a banburying temperature of 90°C and a time of 7min to obtain a first banburying rubber; the rubber matrix is ​​a compound of styrene-butadiene rubber and butadiene rubber, and the mass ratio of SBR to BR is 3:1; the reaction temperature of the polyurethane prepolymer is 70°C and the time is 2.5h;

[0065] Step (4) rolling the first mixed rubber into a sheet with a thickness of 2 mm;

[0066] Step (5) Plasma treatment is performed on both sides of the sheet, with a treatment power of 75 W, a time of 15 seconds, and a gas of argon / oxygen mixed gas with a volume ratio of 2:1 and a pressure of 30 Pa;

[0067] Step (6) The sheet after plasma treatment is cut into particles with a particle size of 3 mm to obtain modified rubber particles;

[0068] Step (7) 2 parts by mass of vulcanizing agent DCP, 0.7 parts by mass of accelerator TAC, 0.7 parts by mass of antioxidant RD, and 3 parts by mass of aerogel are added to 100 parts by mass of modified rubber particles, and secondary mixing is performed, with a mixing temperature of 80°C and a mixing time of 5 minutes, to obtain a secondary mixing rubber; the aerogel is silica aerogel modified by silane coupling agent KH-560 on the surface, and the modification method is as follows: the aerogel particles and KH-560 are mixed at a mass ratio of 100:1, heated to 100°C and reacted for 2.5h, then filtered and dried;

[0069] Step (8) The secondary mixing rubber is molded and vulcanized at 165°C for 15 minutes to obtain a modified rubber runway composite containing DPU waste;

[0070] The polyurethane prepolymer is generated by reacting DPU with polyether polyol with a molecular weight of 2500 at a mass ratio of 1:2, with a reaction temperature of 70°C and a reaction time of 2.5h, and the -NCO content in the prepolymer is 3.5wt%; the aerogel is silica aerogel with a particle size of 12μm;

[0071] Preparation of polyurethane prepolymer modified rubber particles: 6 parts of butadiene styrene rubber and cis-butadiene rubber compound (SBR:BR=3:1) and 1 part of polyurethane prepolymer (DPU:polyether polyol=1:2, molecular weight 2500) are added to a mixing machine, and sheared at 90°C and 22rpm for 7 minutes, 0.8% of antioxidant 4020 and 1.8% of plasticizer naphthenic oil based on the mass of the rubber matrix are added; after the blending is completed, the material is unloaded to a flat vulcanizing machine, and a uniform sheet is formed by pressing at a pressure of 8MPa and a temperature of 98°C for 3.5min, and then cooled to room temperature, and then cut into particles by a pulverizer to obtain polyurethane prepolymer modified rubber particles.

[0072] Example 3

[0073] A method for preparing a modified rubber runway composite containing DPU waste, comprising the following steps:

[0074] Step (1) After drying the DPU waste to a moisture content of ≤0.3%, grind to a particle size of 100μm to obtain DPU waste particles; the DPU waste in step (1) is industrial waste of 4,4'-diphenyl methane diisocyanate, and the drying is performed by vacuum drying at a temperature of 70°C for 2h;

[0075] Step (2) performing surface modification treatment on the DPU waste particles: mixing the DPU waste particles with a silane coupling agent KH-550 in a mass ratio of 100:3, heating to 80° C. for reaction for 1 hour, filtering and drying to obtain surface-modified DPU waste particles;

[0076] Step (3) The polyurethane prepolymer modified rubber particles and the surface modified DPU waste particles are mixed in a mass ratio of 3:1, and the total mass after mixing is 100 mass parts, 5 mass parts of sulfur as a vulcanizing agent, 3 mass parts of DM as an accelerator, 40202 mass parts of an antioxidant, 4 mass parts of DOP as a plasticizer, and 30 mass parts of calcium carbonate as a filler are added, and the first banburying is performed at a banburying temperature of 100°C and a time of 5 minutes to obtain a first banburying rubber; the rubber matrix is ​​a compound of styrene-butadiene rubber and butadiene rubber, and the mass ratio of SBR to BR is 4:1; the reaction temperature of the polyurethane prepolymer is 80°C and the time is 2 hours;

[0077] Step (4) rolling the first mixed rubber into a sheet with a thickness of 3 mm;

[0078] Step (5) plasma treatment is performed on the front and back of the wafer, with a treatment power of 100 W, a time of 10 seconds, an argon / oxygen mixed gas volume ratio of 3:1, and a pressure of 10 Pa;

[0079] Step (6) chopping the plasma-treated flakes into particles of 5 mm to obtain modified rubber particles;

[0080] Step (7) Based on the mass of the modified rubber particles as 100 parts by mass, 3 parts by mass of sulfur as a vulcanizing agent, 1.5 parts by mass of DM as an accelerator, 1 part by mass of antioxidant 4020, and 5 parts by mass of aerogel are added, and secondary mixing is performed at a mixing temperature of 90° C. for 3 minutes to obtain a secondary mixed rubber; the aerogel is a silica aerogel whose surface is modified with a silane coupling agent KH-560, and the modification method is: mixing the aerogel particles and KH-560 in a mass ratio of 100:2, heating to 100° C. for reaction for 2 hours, filtering and drying;

[0081] Step (8) vulcanizing the secondary mixed rubber at 180° C. for 10 min to obtain a modified rubber track composite material containing DPU waste;

[0082] The polyurethane prepolymer is prepared by reacting DPU with a polyether polyol having a molecular weight of 3000 in a mass ratio of 1:3, at a reaction temperature of 80°C for 2 hours, and the -NCO content in the prepolymer is 5 wt%. The aerogel is a silica aerogel with a particle size of 20 μm.

[0083] Preparation of polyurethane prepolymer modified rubber particles: 7 parts of a mixture of styrene-butadiene rubber and butadiene rubber (SBR:BR=4:1) and 1 part of a polyurethane prepolymer (DPU:polyether polyol=1:3, molecular weight 3000) were added to an internal mixer, shear mixed at 20 rpm at 100°C for 5 minutes, and 1% of the weight of the rubber matrix by weight of an antioxidant 4020 and 2% of the weight of the rubber matrix by weight of a plasticizer cyclohexane oil were added; after blending, the material was unloaded to a flat vulcanizer, pressed at a pressure of 10 MPa and a temperature of 100°C for 3 minutes to form a uniform sheet, and then naturally cooled to room temperature and pelletized by a crusher to obtain polyurethane prepolymer modified rubber particles.

[0084] Example 4

[0085] A method for preparing a modified rubber track composite material containing DPU waste comprises the following steps:

[0086] Step (1) drying the DPU waste to a moisture content of ≤0.3% and grinding it to a particle size of 30 μm to obtain DPU waste particles; the DPU waste in step (1) is industrial waste of 4,4'-diphenylmethane diisocyanate and 2,4'-diphenylmethane diisocyanate, and the drying is carried out by vacuum drying at a temperature of 65° C. for 2.5 hours;

[0087] Step (2) performing surface modification treatment on the DPU waste particles: mixing the DPU waste particles with a silane coupling agent KH-560 in a mass ratio of 100:1.5, heating to 75° C. and reacting for 1.8 h, filtering and drying to obtain surface-modified DPU waste particles;

[0088] Step (3) The polyurethane prepolymer modified rubber particles and the surface modified DPU waste particles are mixed in a mass ratio of 4:1, and the total mass after mixing is 100 parts by mass, and 2 parts by mass of vulcanizing agent DCP, 1 part by mass of accelerator TAIC, 1.2 parts by mass of antioxidant 4010NA, 3 parts by mass of plasticizer naphthenic oil, and 15 parts by mass of filler clay are added, and the first banburying is performed at a banburying temperature of 85°C and a time of 8 minutes to obtain a first banburying rubber; the rubber matrix is ​​a compound of styrene-butadiene rubber and butadiene rubber, and the mass ratio of SBR to BR is 3.5:1; the reaction temperature of the polyurethane prepolymer is 75°C and the time is 2.2 hours;

[0089] Step (4) rolling the first mixed rubber into a sheet with a thickness of 1.5 mm;

[0090] Step (5) plasma treatment is performed on the front and back sides of the wafer at a processing power of 60 W for 18 seconds using an argon / oxygen mixed gas with a volume ratio of 2:1 and a pressure of 40 Pa;

[0091] Step (6) chopping the plasma-treated flakes into particles of 4 mm to obtain modified rubber particles;

[0092] Step (7) Based on the mass of the modified rubber particles as 100 parts by mass, 1 part by mass of vulcanizing agent DCP, 0.5 part by mass of accelerator TAIC, 0.5 part by mass of antioxidant 4010NA, and 2 parts by mass of aerogel are added, and secondary mixing is performed at a mixing temperature of 75°C for 6 minutes to obtain a secondary mixed rubber; the aerogel is a silica aerogel whose surface is modified with a silane coupling agent KH-560, and the modification method is: mixing the aerogel particles and KH-560 in a mass ratio of 100:1.2, heating to 90°C for reaction for 2.2 hours, filtering and drying;

[0093] Step (8) vulcanizing the secondary mixed rubber at 160° C. for 18 minutes to obtain a modified rubber track composite material containing DPU waste;

[0094] The polyurethane prepolymer is prepared by reacting DPU with a polyether polyol having a molecular weight of 2200 in a mass ratio of 1:1.5, at a reaction temperature of 75°C and a reaction time of 2.2 hours. The -NCO content in the prepolymer is 4 wt%. The aerogel is a silica aerogel with a particle size of 8 μm.

[0095] Preparation of polyurethane prepolymer modified rubber particles: 5 parts of a mixture of styrene-butadiene rubber and butadiene rubber (SBR:BR=3.5:1) and 1 part of a polyurethane prepolymer (DPU:polyether polyol=1:1.5, molecular weight 2200) are added to an internal mixer, shear mixed at 85°C and 28 rpm for 7 minutes, and 0.6% of the weight of the rubber matrix by weight of an antioxidant 4020 and 1.5% of the weight of the rubber matrix by weight of a plasticizer cyclohexane oil are added; after blending, the material is unloaded to a flat vulcanizer, pressed at a pressure of 7 MPa and a temperature of 92°C for 4.5 minutes to form a uniform sheet, which is naturally cooled to room temperature and then granulated by a grinder to obtain polyurethane prepolymer modified rubber particles.

[0096] Example 5

[0097] A method for preparing a modified rubber track composite material containing DPU waste comprises the following steps:

[0098] Step (1) drying the DPU waste to a moisture content of ≤0.3% and grinding the DPU waste to a particle size of 80 μm to obtain DPU waste particles; the DPU waste in step (1) is industrial waste of 4,4'-diphenylmethane diisocyanate, and the drying is performed by vacuum drying at a temperature of 55° C. for 3.5 hours;

[0099] Step (2) performing surface modification treatment on the DPU waste particles: mixing the DPU waste particles with a silane coupling agent KH-550 in a mass ratio of 100:2.5, heating to 65° C. and reacting for 1.2 h, filtering and drying to obtain surface-modified DPU waste particles;

[0100] Step (3) The polyurethane prepolymer modified rubber particles and the surface modified DPU waste particles were mixed in a mass ratio of 6:1, and based on the total mass of 100 parts by mass after mixing, 4 parts by mass of sulfur, 2 parts by mass of TMTD, 1.8 parts by mass of antioxidant RD, 1.5 parts by mass of liquid paraffin, 25 parts by mass of white carbon black and calcium carbonate were added as vulcanizing agent, accelerator, antioxidant, plasticizer and filler respectively, and the first mixing was carried out at a mixing temperature of 95℃ for 6min to obtain the first mixing rubber; the rubber matrix was a complex of SBR and BR, and the mass ratio of SBR to BR was 2.5:1; the reaction temperature of the polyurethane prepolymer was 65℃, and the reaction time was 2.8h;

[0101] Step (4) The first mixing rubber was rolled into a sheet with a thickness of 2.5mm;

[0102] Step (5) The front and back surfaces of the sheet were treated by plasma at a power of 90W for 12s, and the gas was argon / oxygen mixed gas with a volume ratio of 1:1 at a pressure of 25Pa;

[0103] Step (6) The sheet treated by plasma was cut into particles with a particle size of 3.5mm to obtain modified rubber particles;

[0104] Step (7) Based on 100 parts by mass of the modified rubber particles, 2 parts by mass of sulfur, 1.2 parts by mass of TMTD, 0.8 parts by mass of antioxidant RD and 4 parts by mass of aerogel were added as vulcanizing agent, accelerator, antioxidant and aerogel respectively, and the second mixing was carried out at a mixing temperature of 85℃ for 4min to obtain the second mixing rubber; the aerogel was silica aerogel modified by silane coupling agent KH-560, and the modification method was as follows: the aerogel particles and KH-560 were mixed in a mass ratio of 100:1.8, heated to 85℃ and reacted for 2.8h, then filtered and dried;

[0105] Step (8) The second mixing rubber was molded and vulcanized at 170℃ for 12min to obtain the modified rubber runway composite material containing DPU waste;

[0106] The polyurethane prepolymer was prepared by reacting DPU with polyether polyol with a molecular weight of 2800 in a mass ratio of 1:2.5 at a reaction temperature of 65℃ for 2.8h, and the content of -NCO in the prepolymer was 4.5wt%; the aerogel was silica aerogel with a particle size of 15μm;

[0107] Preparation of polyurethane prepolymer modified rubber particles: 3 parts of a mixture of styrene-butadiene rubber and butadiene rubber (SBR:BR=2.5:1) and 1 part of a polyurethane prepolymer (DPU:polyether polyol=1:2.5, molecular weight 2800) are added to an internal mixer, shear mixed at 95°C and 30 rpm for 8 minutes, and 0.5% of the weight of the rubber matrix by weight of an antioxidant 4020 and 1% of the weight of the rubber matrix by weight of a plasticizer cyclohexane oil are added; after blending, the material is unloaded to a flat vulcanizer, pressed at a pressure of 5 MPa and a temperature of 90°C for 5 minutes to form a uniform sheet, which is naturally cooled to room temperature and then granulated by a crusher to obtain polyurethane prepolymer modified rubber particles.

[0108] Comparative Example 1

[0109] The difference from Example 1 is that the moisture ratio in the DPU waste treatment is not controlled, and the moisture content is 0.5%.

[0110] Comparative Example 2

[0111] The difference from Example 1 is that the DPU waste was not subjected to surface modification.

[0112] Comparative Example 3

[0113] The difference from Example 1 is that during the first mixing, a rubber matrix that has not been modified with a polyurethane prepolymer is selected.

[0114] Comparative Example 4

[0115] The difference from Example 1 is that the first internal mixing of the rubber is rolled into a sheet with a thickness of 3.5 mm.

[0116] Comparative Example 5

[0117] The difference from Example 1 is that the front and back surfaces of the wafer are not plasma treated.

[0118] Comparative Example 6

[0119] The difference from Example 1 is that the plasma treatment process for the front and back sides of the wafer is a processing power of 120 W, a time of 30 seconds, an argon / oxygen mixed gas volume ratio of 2:1, and a pressure of 40 Pa.

[0120] Comparative Example 7

[0121] The difference from Example 1 is that no aerogel component is added.

[0122] Comparative Example 8

[0123] The difference from Example 1 is that the aerogel component is added in excess, 6 parts by mass.

[0124] Comparative Example 9

[0125] The difference from Example 1 is that the molecular weight of polyether polyol is 1500 in the preparation of polyurethane prepolymer.

[0126] Comparative Example 10

[0127] The difference from Example 1 is that the ratio of rubber particles to DPU particles is 8:1 in the first mixing process.

[0128] Comparative Example 11

[0129] The difference from Example 1 is that the ratio of rubber particles to DPU particles is 2:1 in the first mixing process.

[0130] Comparative Example 12

[0131] The difference from Example 1 is that the second mixing temperature is too high, which is 100℃.

[0132] Comparative Example 13

[0133] The difference from Example 1 is that the film pressing vulcanization temperature is too high, which is 190℃.

[0134] Comparative Example 14

[0135] The difference from Example 1 is that the film pressing vulcanization temperature is too low, which is 140℃.

[0136] Performance test:

[0137] Tensile strength: tested according to the method specified in GB / T10654.

[0138] Elongation at break: tested according to the method specified in GB / T10654.

[0139] Impact absorption: tested according to the method specified in GB / T36246.

[0140] TVOC release amount: tested according to the method specified in GB / T36246.

[0141] The test results are shown in Table 1.

[0142] Table 1 Performance test results of examples and comparative examples

[0143]

[0144]

[0145] The performance advantage of the present invention comes from the deep synergy between the functions of the components and the process steps. DPU waste is strictly dried and surface-modified with a silane coupling agent to construct an active functional group layer on the particle surface, significantly enhancing the chemical bonding ability with the rubber matrix; the polyurethane prepolymer acts as a reactive medium, and its isocyanate group cross-links with the rubber molecular chain during kneading to form an interpenetrating network, providing a uniformly dispersed skeleton structure for the surface-modified DPU particles; plasma treatment generates polar oxygen-containing groups on the surface of the sheet through high-energy particle bombardment, greatly improving the surface wettability and creating active sites for the subsequent interfacial bonding of the aerogel; after the aerogel is pre-modified with a silane coupling agent, its surface groups are bonded to the plasma-activated layer through hydrogen bonds and chemical bonds, achieving stable embedding in the low-temperature secondary kneading. The composite structure improves mechanical strength through a rigid reinforcing phase, and its porous properties simultaneously optimize thermal insulation and anti-aging functions; the final compression vulcanization process accurately matches the cross-linking dynamics, so that the interfaces of each component are fused into a dense whole, achieving a synergistic improvement in strength, elasticity and durability.

[0146] Compared with Example 1, Comparative Example 1 causes the silane bond to hydrolyze due to excessive moisture in the DPU, the interface micropore weakens stress transfer, leading to mechanical property degradation, and the hydrolysis byproduct releases formaldehyde and carboxylic acid, increasing TVOC; Comparative Example 2, the inert surface of unmodified DPU induces phase separation to form stress concentration points, reducing strength and toughness, and the plasticizer continues to seep along the interface cracks, intensifying TVOC release; Comparative Example 3, the absence of a pre-polymer compatibilizer causes DPU to agglomerate, blocking stress transfer paths, impact absorption drops sharply, and the loose crosslinked network releases promoter byproducts, increasing TVOC; Comparative Example 4, excessive thickness limits plasma deep layer activation, and the aerogel bonding is insufficient, weakening mechanical properties, and the unreacted hydrophobic area enriched plasticizer increases TVOC release upon thermal release; Comparative Example 5, without plasma treatment, the aerogel is easily detached due to physical adsorption, impact performance decreases, and unbound silane desorption is volatile siloxane; Comparative Example 6, plasma overloading etches the substrate molecular chain, causing brittle fracture, and aldehyde and ketone TVOC is generated by oxidation of alkane fragments; Comparative Example 7, without an aerogel system, the rigid reinforcing and pore anchoring functions are lost, and mechanical properties are comprehensively reduced, with free migration and release of plasticizers; Comparative Example 8, excessive aerogel agglomeration cuts off the continuous phase, causing stress concentration, and the interface adsorbs antioxidants that are thermally decomposed into quinone volatile substances; Comparative Example 9, low molecular weight polyether polyol causes uneven crosslinked networks, local stress overload accelerates fracture, and free monomers and DCP byproducts are released simultaneously; Comparative Example 10, low DPU ratio causes the matrix to overload and yield, and high plasticizer exposure increases the specific surface area, promoting TVOC release; Comparative Example 11, high DPU ratio exceeds the dispersion limit, causing interface debonding, and uncoated DPU releases free isocyanate; Comparative Example 12, secondary mixing at high temperature causes the aerogel to collapse, losing reinforcement, and silane fracture releases oligomers; Comparative Example 13, ultra-high temperature vulcanization causes molecular chain fracture and DPU thermal decomposition, pore defects weaken mechanical properties, and toxic substances are released from alkene / 4,4'-MDA; Comparative Example 14, insufficient vulcanization forms a weak boundary layer, and residual sulfur generates sulfur compounds; all defects weaken mechanical bearing through interface failure and open a low molecular release channel through byproduct reactions, collapsing the component-process synergistic protection system.

[0147] The core advantage of the present application lies in the precise coupling and parallel of component functions and process parameters: deep drying and silane coupling agent modification build an active layer on the surface of DPU waste, eliminating weak boundaries through covalent bond anchoring; polyurethane prepolymer and rubber matrix form an interpenetrating network, providing a molecularly dispersed skeleton for modified DPU; plasma accurately activates the surface of the sheet to generate oxygen-containing polar groups, forming a hydrogen bond-covalent bond hybrid interface with the silicon hydroxyl groups of KH-560 modified aerogel, achieving rigid-elastic phase synergistic reinforcement; low-temperature secondary mixing protects the porous structure of the aerogel, and its nanopores simultaneously adsorb free plasticizer molecules; optimizing the vulcanization temperature-time window ensures the complete development of the crosslinked network, and the synergy of components and processes enables efficient stress transfer at the interface, hinders crack propagation, and dual-locks the byproduct fragments and unreacted monomers by the dense network and aerogel pores.

Claims

1. A modified rubber track composite material containing DPU waste, characterized in that: Prepared by the following steps: Step (1) drying the DPU waste to a moisture content of ≤0.3%, and then grinding the DPU waste to a particle size of 10-100 μm to obtain DPU waste particles; Step (2) performing surface silane modification treatment on the DPU waste particles to obtain surface-modified DPU waste particles; Step (3) mixing the polyurethane prepolymer modified rubber particles and the surface modified DPU waste particles in a mass ratio of 3-7:1, adding 1-5 mass parts of a vulcanizing agent, 0.5-3 mass parts of an accelerator, 0.5-2 mass parts of an antioxidant, 1-4 mass parts of a plasticizer, and 10-30 mass parts of a filler to 100 mass parts of the total mass after the mixture, and performing a first banburying to obtain a first banburying rubber; Step (4) rolling the first mixed rubber into a sheet with a thickness of 1-3 mm; Step (5) plasma treatment of the front and back surfaces of the sheet; Step (6) chopping the plasma-treated flakes into particles of 2-5 mm to obtain modified rubber particles; Step (7) adding 1-3 parts by mass of a vulcanizing agent, 0.3-1.5 parts by mass of an accelerator, 0.3-1 parts by mass of an antioxidant, and 1-5 parts by mass of an aerogel to 100 parts by mass of the modified rubber particles, and performing secondary mixing to obtain a secondary mixed rubber; Step (8) vulcanizes the secondary rubber mixture at 150-180° C. for 10-20 minutes to obtain a modified rubber track composite material containing DPU waste.

2. The modified rubber track composite material containing DPU waste according to claim 1, characterized in that: In step (2), the process for surface modification of DPU waste particles is as follows: mixing DPU waste particles with silane coupling agent in a mass ratio of 100:1-3, heating to 60-80°C for reaction for 1-2h, filtering and drying to obtain surface-modified DPU waste particles.

3. The modified rubber track composite material containing DPU waste according to claim 1, characterized in that: In step (3), the first banburying process is as follows: banburying temperature 80-100° C., time 5-10 min.

4. The modified rubber track composite material containing DPU waste according to claim 1, characterized in that: In step (3), the rubber matrix is ​​a compound of styrene-butadiene rubber and butadiene rubber in a mass ratio of 2-4:1; the filler is at least one of carbon black, white carbon black, clay or calcium carbonate; and the plasticizer is at least one of naphthenic oil, liquid paraffin or dioctyl phthalate; The vulcanizing agent is sulfur or dicumyl peroxide; when the vulcanizing agent is sulfur, the accelerator is at least one of cyclohexylthiophthalimide, 2,2'-dibenzothiazole disulfide, or tetramethylthiuram disulfide; when the vulcanizing agent is dicumyl oxide, the accelerator is at least one of triallyl isocyanurate or triallyl cyanurate; The antioxidant is at least one of N-isopropyl-N'-phenyl-p-phenylenediamine, 2,2,4-trimethyl-1,2-dihydroquinoline polymer or N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine.

5. The modified rubber track composite material containing DPU waste according to claim 1, characterized in that: The process of plasma treatment on the front and back sides of the wafer in step (5) is as follows: treatment power 50-100W, time 10-20 seconds, gas is argon / oxygen mixed gas with a volume ratio of 1-3:1, and pressure 10-50Pa.

6. The modified rubber track composite material containing DPU waste according to claim 1, characterized in that: In step (7), the process of secondary banburying is as follows: banburying temperature is 70-90° C., and time is 3-8 min.

7. The modified rubber track composite material containing DPU waste according to claim 1, characterized in that: In step (7), the aerogel is a silica aerogel whose surface is modified with a silane coupling agent; the modification method is: mixing aerogel particles and a silane coupling agent in a mass ratio of 100:0.5-2, heating to 80-100° C. for reaction for 2-3 hours, filtering and drying; In step (7), when the vulcanizing agent is sulfur, the amount of the accelerator is 0.3-1.5 parts by mass; when the vulcanizing agent is diisopropylbenzene oxide, the amount of the accelerator is 0.3-1 parts by mass.

8. The modified rubber track composite material containing DPU waste according to claim 1, characterized in that: The preparation process of the polyurethane prepolymer modified rubber particles in step (3) is as follows: 3-7 parts of rubber matrix and 1 part of polyurethane prepolymer are added to an internal mixer, shear mixed at 80-100°C and a speed of 20-30rpm for 5-8 minutes, 0.5-1% of the weight of the rubber matrix antioxidant and 1-2% of the weight of the rubber matrix plasticizer are added. After the blending is completed, the material is unloaded into a flat vulcanizer, and pressed at a pressure of 5-10MPa and a temperature of 90-100°C for 3-5 minutes to form a uniform sheet. After naturally cooling to room temperature, the sheet is granulated by a grinder to obtain polyurethane prepolymer modified rubber particles.

9. The modified rubber track composite material containing DPU waste according to claim 8, characterized in that: The polyurethane prepolymer is produced by reacting DPU with polyether polyol having a molecular weight of 2000-3000 in a mass ratio of 1:1-1:

3.

10. A method for preparing a modified rubber track composite material containing DPU waste according to any one of claims 1 to 9, characterized in that: The following steps are involved: Step (1) DPU waste pretreatment; Step (2) preparing surface-modified DPU waste particles; Step (3) performing the first internal mixing to obtain the first internal mixing rubber; Step (4) rolling the sheet; Step (5) plasma treatment of the wafer; Step (6) shredding the plasma-treated flakes to prepare modified rubber particles; Step (7) secondary mixing to obtain secondary mixed rubber; Step (8) mold-vulcanizes the secondary mixed rubber to obtain a modified rubber track composite material containing DPU waste.

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