Sealant for light-weight vehicle body and preparation method thereof

Abstract

The application relates to the technical field of sealant, in particular to a light-weight sealant for a vehicle body and a preparation method thereof.The light-weight sealant for the vehicle body comprises a silane modified polymer, a plasticizer, a filler, a thixotropic agent, an ultraviolet resistance agent, a light stabilizer, a heat stabilizer, a water removal agent, a silane coupling agent and a curing agent; wherein zinc oxide and aluminum hydroxide can reduce hydrogen ions in the sealant, organic bentonite can reduce water in the sealant, the zinc oxide, the aluminum hydroxide, the organic bentonite, the water removal agent and the heat stabilizer are used in combination to weaken the conditions for hydrolysis of ether bonds in the sealant, the stability of the heat stabilizer is further enhanced, and / or the stability of the heat stabilizer to capture free active groups is enhanced, so that the sealant has excellent water resistance and heat stability.

Description

Technical Field

[0001] This application relates to the field of sealant technology, and in particular to a lightweight car body sealant and its preparation method. Background Technology

[0002] Sealant is a material used to fill voids and seams. In the automotive manufacturing industry, it is mainly used for bonding and sealing components such as windshields, headlights, doors and windows, sunroofs, and interior trim, serving functions such as waterproofing, dustproofing, and sound insulation.

[0003] With increasing awareness of energy conservation, emission reduction, and environmental protection, weight reduction has become an important development direction for automobiles. Under the trend of automotive lightweighting, the density of automotive sealing strips needs to be reduced, while the sealant also needs to have good elasticity and flexibility, excellent tear strength, heat resistance, water resistance, and chemical resistance.

[0004] Currently, the sealants used in the market are mainly silicone and polyurethane. Silicone sealants have excellent aging resistance, but poor mechanical properties and stain resistance, and low adhesion strength to the substrate. Polyurethane sealants have advantages such as good elasticity, low temperature resistance, wear resistance, and good adhesion to the substrate interface, but their weather resistance and heat resistance are not very good. Moreover, because polyurethane sealants contain the polarity of polyester or polyether, their water resistance is poor.

[0005] In summary, the main chain of existing sealants contains -COC- ether bonds, which determines that these sealants have poor water resistance and high temperature resistance. The performance of the sealants deteriorates significantly after prolonged contact with water or exposure to high temperatures. Summary of the Invention

[0006] To overcome the problems of poor water resistance and high-temperature performance of existing sealants, this application provides a lightweight sealant for vehicle bodies and its preparation method.

[0007] In the first aspect, this application provides a lightweight sealant for car bodies, employing the following technical solution: A lightweight car body sealant, comprising the following components by weight: 140-180 parts of silane-modified polymer; Plasticizer 60-90 parts; 250-350 parts of filler; 4-10 parts of thixotropic agent; UV protectant 0.5-3 parts; Light stabilizer 0.5-3 parts; Heat stabilizer 0.5-3 parts; 3-10 parts of dehydrating agent; 3-8 parts of silane coupling agent; 1-3 parts of curing agent; The filler comprises 20-40 parts of organic bentonite, 20-40 parts of zinc oxide, 20-50 parts of aluminum hydroxide and 190-220 parts of filler A; The dehydrating agent is vinyltrimethoxysilane or vinyltriethoxysilane; The heat stabilizer is at least one of hindered phenolic antioxidants and phosphite antioxidants.

[0008] By adopting the above technical solution, zinc oxide and aluminum hydroxide can combine with hydrogen ions, reducing the number of hydrogen ions. Organic bentonite can adsorb water molecules, thereby reducing the contact between water and ether bonds, and further reducing the possibility of hydrolysis of ether bonds under the catalysis of hydrogen ions, thus enhancing the hydrolysis resistance of the sealant. The heat stabilizer has the ability to capture active free radicals, reducing the aging and breakage of -COC- ether bonds. In this application, zinc oxide, aluminum hydroxide, organic bentonite, dehydrating agent and heat stabilizer are used in combination. Zinc oxide and aluminum hydroxide reduce hydrogen ions in the sealant, and organic bentonite reduces water in the sealant, making the heat stabilizer more stable and / or the heat stabilizer more stable in capturing free active groups, further enhancing the thermal stability of the sealant, thereby giving the sealant excellent water resistance and thermal stability.

[0009] Preferably, the filler A comprises 30-60 parts by weight of asbestos fiber and 160 parts by weight of filler B, wherein filler B is one or more of calcium carbonate, clay, talc, and carbon black.

[0010] By adopting the above technical solution, the use of low-density asbestos fibers as fillers in the sealant further reduces the weight of the automotive sealant, while enhancing its high-temperature resistance, thermal insulation, and mechanical strength. Furthermore, asbestos fibers have excellent water absorption properties, which can reduce the moisture content in the sealant. Moreover, asbestos fibers have a high aspect ratio, which makes it easier to expel moisture from the sealant when it is heated, thereby reducing the moisture content in the sealant and enhancing its hydrolysis resistance, mechanical strength, and heat resistance.

[0011] Preferably, the filler B is calcium carbonate, talc, and carbon black in a mass ratio of 2:(0.5-4):2.

[0012] By adopting the above technical solution, the composition of component B is optimized, and calcium carbonate, talc, and carbon black are used in combination. Carbon black and calcium carbonate play a toughening and reinforcing role, while talc plays a lubricating role, thereby adjusting the dispersibility between the raw materials of the sealant and enhancing the effectiveness of each raw material and the synergistic effect between the raw materials. In this application, by using filler B in a mass ratio of calcium carbonate, talc, and carbon black of 2:(0.5-4):2, the hydrolysis resistance, mechanical strength, and heat resistance of the sealant are further enhanced.

[0013] Preferably, the silane-modified polymer is a silane-terminated polyether polymer or a silane-modified polyurethane polymer.

[0014] By adopting the above technical solutions, silane-modified polyether sealant and silane-modified polyurethane polymer sealant are preferred, as they exhibit excellent adhesion to various substrates.

[0015] Furthermore, silane-modified polyurethane polymers are preferred. These polymers have both soft and hard segments, with the hard segments imparting excellent mechanical strength to the silane-modified polyurethane polymers.

[0016] Because asbestos fibers are short, brittle, and easily broken, the network structure of the silane-modified polyurethane polymer synergistic sealant selected in this application plays a skeletal support role in the sealant, providing better protection for the asbestos fibers. This, in turn, allows the asbestos fibers to perform better reinforcement functions and improves the heat resistance and water resistance of the sealant.

[0017] Preferably, the silane-terminated polyether polymers are Kaneka's S203H, S303H, SAX260, and SAX750; the silane-modified polyurethane polymers are AGC's SX3430E, SX6735D, and S888E. STP-E15, STP-E35; one of Momentive's SPUR+*1015, SPUR+*1012, SPUR+*3030, SPUR+*3040.

[0018] By adopting the above technical solutions, the brands and manufacturers of silane-modified polyether sealants and silane-modified polyurethane polymer sealants are optimized. Silane-modified polymers have relatively stable performance and good compatibility with other raw materials, thereby enhancing the sealant's hydrolysis resistance, mechanical strength, and heat resistance.

[0019] Preferably, the plasticizer is at least one of phthalate compounds and polyether polyols; the thixotropic agent is at least one of polyamide wax, hydrogenated castor oil, and silica.

[0020] By adopting the above technical solutions, plasticizers improve the flexibility of sealants; thixotropic agents give sealants properties such as non-stringing, non-flowing, and thixotropic properties, resulting in good workability.

[0021] Preferably, the light stabilizer is a hindered amine light stabilizer; and the UV stabilizer is a benzotriazole UV stabilizer.

[0022] By adopting the above technical solution, light stabilizers and UV stabilizers are used in combination to reduce the aging of the sealant by light, thereby improving the weather resistance of the sealant.

[0023] Preferably, the curing agent is a chelated tin catalyst.

[0024] By adopting the above technical solution, the chelated tin catalyst promotes the cross-linking of the raw materials of the sealant; at the same time, it has good adhesion to a variety of substrates and has a certain water removal ability. When the chelated tin catalyst is used in combination with zinc oxide, aluminum hydroxide, organobentonite, water removal agent and heat stabilizer, the water resistance and thermal stability of the sealant are further improved.

[0025] Preferably, the silane coupling agent is an aminosilane selected from γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, phenylamino-silane, triaminosilane, γ-mercaptopropyltrimethoxysilane, γ-ureapropyltrimethoxysilane, γ-ureapropyltrihexyloxysilane, γ-methacryloyloxypropyltrimethoxysilane, and γ-glycidyl etheryltrimethoxysilane.

[0026] By adopting the above technical solution, silane coupling agents are used to improve the wet adhesion of the sealant and enhance the dispersibility of the filler, thereby further strengthening the sealant's mechanical strength, water resistance, and heat resistance. Secondly, this application provides a method for preparing the lightweight body sealant of this application.

[0027] A method for preparing a lightweight car body sealant includes the following steps: The silane-modified polymer, plasticizer, filler, thixotropic agent, UV stabilizer, light stabilizer and heat stabilizer are mixed under a vacuum of not less than 980 mbar and a stirring speed of 600-800 rpm / min. Then heat to 110-130℃ and dehydrate for 120-140 minutes under a vacuum of not less than 980mbar and a stirring speed of 300-600rpm / min. Next, the temperature is lowered to 40-45℃, a dehydrating agent is added, and the mixture is stirred for 20-30 minutes at a speed of 250-300 rpm / min; a silane coupling agent is added, and the mixture is stirred for 25-35 minutes at a speed of 250-300 rpm / min; a curing agent is added, and the mixture is stirred for 25-35 minutes at a vacuum of not less than 980 mbar and a speed of 250-300 rpm / min to prepare a lightweight car body sealant.

[0028] By adopting the above technical solution, the moisture in the sealant raw material is effectively removed, and the raw material in the sealant is well dispersed, so that the prepared sealant has excellent mechanical properties, heat resistance and water resistance.

[0029] In summary, this application has the following beneficial effects: 1. The use of zinc oxide, aluminum hydroxide, organic bentonite, dehydrating agent and heat stabilizer in the raw materials of the sealant reduces the conditions for ether bond hydrolysis in the sealant, making the heat stabilizer and / or the heat stabilizer more stable in capturing free active groups, thereby enhancing the thermal stability and water resistance of the sealant.

[0030] 2. The use of asbestos fibers in the filler further reduces the weight of the automotive sealant due to their lower density, while also enhancing the sealant's high-temperature resistance, thermal insulation, and mechanical strength. Furthermore, asbestos fibers absorb moisture from the sealant, and their high aspect ratio allows for easier removal of moisture from the sealant's interior, thereby reducing the moisture content and enhancing the sealant's hydrolysis resistance, mechanical strength, and heat resistance.

[0031] 3. The preferred silane-modified polymer is a silane-modified polyurethane polymer. Silane-modified polyurethane polymers not only have excellent adhesion to various substrates, but also the hard segments in the silane-modified polyurethane polymer form a network structure after curing, which weakens the force on the asbestos fibers, allowing the asbestos fibers in the sealant to better maintain their aspect ratio, thereby enhancing the heat resistance, water resistance and mechanical strength of the sealant. Detailed Implementation

[0032] raw material Silyl-terminated polyether polymer S203H (brand: Kaneka Corporation, Japan), silane-modified polyurethane polymer SPUR+*1015 (brand: Momentive), silyl-terminated polyether polymer SX3430E (brand: AGC Asahi Glass, Japan), organobentonite (average particle size 15μm), asbestos fiber (fiber length 1-3mm), calcium carbonate (average particle size 15μm), talc (average particle size 15μm), titanium dioxide (average particle size 15μm), carbon black (N550 carbon black), hydrogenated castor oil (grade: premium grade), hollow glass beads (average particle size 37μm, vacuum density: 0.38). Example

[0033] Example 1: A lightweight car body sealant, the raw materials of which are shown in Table 1, and its preparation method includes the following steps: The silane-modified polymer, plasticizer, filler, thixotropic agent, UV stabilizer, light stabilizer and heat stabilizer were added to a double planetary mixer and stirred under vacuum (1000 mbar) at a stirring speed of 800 rpm / min for 60 min.

[0034] Then heat to 110℃ and dehydrate for 120 minutes under a vacuum of 1000 mbar and a stirring speed of 600 rpm / min.

[0035] Next, the temperature was lowered to 45°C, a dehydrating agent was added, and the mixture was stirred for 20 minutes at a speed of 250 rpm / min. Then, a silane coupling agent was added, and the mixture was stirred for 25 minutes at a speed of 250 rpm / min. Finally, a curing agent was added, and the mixture was stirred for 25 minutes at a vacuum of not less than 980 mbar and a speed of 250 rpm / min to prepare a lightweight car body sealant.

[0036] Example 2 is a lightweight car body sealant, which differs from Example 1 in that the types and weights of the raw materials are different, as detailed in Table 1; the process parameters in the preparation method are also different, and the specific steps are as follows: The silane-modified polymer, plasticizer, filler, thixotropic agent, UV stabilizer, light stabilizer and heat stabilizer were added to a double planetary mixer and stirred under vacuum (1100 mbar) at a stirring speed of 700 rpm / min for 65 min.

[0037] Then heat to 120℃ and dehydrate for 130 min under a vacuum of 1100 mbar and a stirring speed of 400 rpm / min.

[0038] Next, the temperature was lowered to 42°C, a dehydrating agent was added, and the mixture was stirred for 25 minutes at a speed of 280 rpm / min. Then, a silane coupling agent was added, and the mixture was stirred for 30 minutes at a speed of 280 rpm / min. Finally, a curing agent was added, and the mixture was stirred for 30 minutes at a vacuum of not less than 980 mbar and a speed of 280 rpm / min to prepare a lightweight car body sealant.

[0039] Example 3 is a lightweight car body sealant, which differs from Example 1 in that the types and weights of the raw materials are different, as detailed in Table 1; the process parameters in the preparation method are also different, and the specific steps are as follows: The silane-modified polymer, plasticizer, filler, thixotropic agent, UV stabilizer, light stabilizer and heat stabilizer were added to a double planetary mixer and stirred under vacuum (vacuum degree of 1200 mbar) at a stirring speed of 600 rpm / min for 70 min. Then heat to 130℃ and dehydrate for 140 min under a vacuum of 1200 mbar and a stirring speed of 300 rpm / min.

[0040] Next, the temperature was lowered to 40°C, a dehydrating agent was added, and the mixture was stirred for 30 minutes at a speed of 300 rpm / min. Then, a silane coupling agent was added, and the mixture was stirred for 35 minutes at a speed of 300 rpm / min. Finally, a curing agent was added, and the mixture was stirred for 35 minutes at a vacuum of 1200 mbar and a speed of 300 rpm / min to prepare a lightweight car body sealant.

[0041] Table 1 lists the types and weights of raw materials in the lightweight car body sealants of Examples 1-3. Filler B1 is a composition of calcium carbonate, talc, and carbon black in a mass ratio of 2:2:2; filler B2 is a composition of calcium carbonate, talc, and clay in a mass ratio of 2:2:1.

[0042] In other embodiments, the plasticizer may be one or more of diisooctyl phthalate, diisodecyl phthalate, PPG2000, PPG3000 and PPG8000.

[0043] In other embodiments, the light stabilizer may be light stabilizer 765 and light stabilizer 5050H.

[0044] In other embodiments, the heat stabilizer is a van truss antioxidant. CA-SF.

[0045] In other embodiments, the chelated tin catalyst may be commercially available grade TIB 226.

[0046] In other embodiments, the silane coupling agent may be one of γ-aminopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, phenylamino-silane, triaminosilane, γ-ureapropyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, and γ-glycidyl etheryltrimethoxysilane.

[0047] Example 4, a lightweight car body sealant, differs from Example 1 in that it uses Momentive's silane-modified polyurethane polymer SPUR+*1012 in an equal amount to replace the silane-modified polyurethane polymer SPUR+*1015.

[0048] Example 5, a lightweight sealant for car bodies, differs from Example 1 in that hollow glass beads are used to replace asbestos fibers in equal amounts.

[0049] Example 6, a lightweight car body sealant, differs from Example 1 in that it uses an equal amount of Kaneka's silane-terminated polyether polymer S203H to replace the silane-modified polyurethane polymer SPUR+*1015.

[0050] Example 7, a lightweight car body sealant, differs from Example 1 in that it uses an equal amount of silane-modified polyurethane polymer SPUR+*1015, which is a silane-terminated polyether polymer SX6735D from AGC Corporation.

[0051] Example 8, a lightweight sealant for car bodies, differs from Example 6 in that hollow glass beads are used to replace asbestos fibers in equal amounts.

[0052] Example 9, a lightweight car body sealant, differs from Example 1 in that filler B uses calcium carbonate, talc, and carbon black in a mass ratio of 2:0.5:2.

[0053] Example 10, a lightweight car body sealant, differs from Example 1 in that filler B is calcium carbonate, talc, and carbon black in a mass ratio of 2:1:2.

[0054] Example 11, a lightweight car body sealant, differs from Example 1 in that filler B uses calcium carbonate, talc, and carbon black in a mass ratio of 2:3:2.

[0055] Example 12, a lightweight car body sealant, differs from Example 1 in that filler B uses calcium carbonate, talc, and carbon black in a mass ratio of 2:4:2.

[0056] Example 13, a lightweight car body sealant, differs from Example 1 in that it uses calcium carbonate in an equal amount to replace carbon black.

[0057] Example 14, a lightweight car body sealant, differs from Example 1 in that carbon black is used to replace calcium carbonate in equal amounts.

[0058] Example 15, a lightweight car body sealant, differs from Example 1 in that carbon black is used to replace talc powder in an equal amount.

[0059] Comparative Example Comparative Example 1, a lightweight car body sealant, differs from Example 15 in that it uses an equal amount of aluminum hydroxide instead of zinc oxide.

[0060] Comparative Example 2, a lightweight car body sealant, differs from Example 15 in that it uses titanium dioxide in an equal amount to replace zinc oxide.

[0061] Comparative Example 3, a lightweight car body sealant, differs from Example 15 in that it does not use organic bentonite and a water-removing agent.

[0062] Comparative Example 4, a lightweight car body sealant, differs from Example 15 in that it does not use zinc oxide and aluminum hydroxide.

[0063] Comparative Example 5, a lightweight car body sealant, differs from Example 15 in that it does not use zinc oxide, aluminum hydroxide, organobentonite, or a water-removing agent.

[0064] Comparative Example 6, a lightweight car body sealant, differs from Example 15 in that it does not use a heat stabilizer.

[0065] Comparative Example 7, a lightweight car body sealant, differs from Example 15 in that it does not use zinc oxide, aluminum hydroxide, organobentonite, dehydrating agent, and heat stabilizer.

[0066] Performance testing Test 1: Shear Strength Refer to GB / T7124-2008 "Determination of Tensile Shear Strength of Adhesives" (adhesive thickness 2mm).

[0067] The test samples were immersed in water at 60°C for 48 hours. Then they were dried in a drying oven at 60°C for 20 hours. After drying, they were placed in a desiccator to cool to room temperature (N=6 samples were tested for each sample, and the average value was taken).

[0068] The test samples were immersed in water at 85°C for 48 hours. Then they were dried in a drying oven at 60°C for 20 hours. After drying, they were placed in a desiccator to cool to room temperature (N=6 samples were tested for each sample, and the average value was taken).

[0069] Test 2: Tensile strength and elongation at break The tensile strength and elongation at break of the sealant were tested according to GB / T528-2009.

[0070] Test 3: Impermeability The impermeability was tested according to GB / T 23445-2009 "Polymer Cement Waterproof Coatings" (coating thickness 1.0 mm).

[0071] Test samples: Lightweight body sealants of Examples 1-15 were used as example samples; lightweight body sealants of Comparative Examples 1-7 were used as control samples.

[0072] Experimental results: The experimental results of shear strength, tensile strength, elongation at break and impermeability of the lightweight car body sealants of Examples 1-15 and Comparative Examples 1-7 are shown in Table 2.

[0073] Table 2 lists the experimental results of shear strength, tensile strength, elongation at break, and impermeability of the lightweight car body sealants of Examples 1-15 and Comparative Examples 1-7. Combining Examples 1-15 and Comparative Examples 1-7 with Table 2, it can be seen that: The shear strength, tensile strength, elongation at break, and impermeability of Examples 1-15 are superior to those of Comparative Examples 1-7. This may be because the use of zinc oxide, aluminum hydroxide, organobentonite, dehydrating agent, and heat stabilizer in Examples 1-15 reduces the conditions for ether bond hydrolysis in the sealant and enhances the stability of the heat stabilizer and / or the heat stabilizer in capturing free active groups, thereby giving the sealant excellent water resistance and thermal stability. Furthermore, the use of asbestos fiber, silane-modified polyurethane polymer, and preferred fillers in the raw materials of the sealant further reduces the moisture content in the sealant and enhances its strength and toughness, resulting in excellent hydrolysis resistance, mechanical strength, and heat resistance.

[0074] The experimental results from Examples 1 and 4-8 show that the shear strength, tensile strength, elongation at break, and impermeability of Examples 1 and 4 are superior to those of Examples 6-7; the shear strength, tensile strength, elongation at break, and impermeability of Example 5 are superior to those of Example 8. This may be because silane-modified polyurethane polymers were used in Examples 1, 4, and 5. Compared with silane-terminated polyether polymers, silane-modified polyurethane polymers have better compatibility with asbestos fibers or hollow glass beads. This may be because the molecular structure of silane-modified polyurethane polymers contains hard and soft segments. The hard segments of the molecular structure of silane-modified polyurethane polymers and the network structure after the sealant is formed become the skeleton structure of the sealant, which better protects the asbestos fibers or hollow glass beads. This makes it less likely for the asbestos fibers or hollow glass beads to break or rupture under external force, thus better exerting the effects of reinforcement, heat resistance, water absorption, and moisture wicking. This results in the sealant having excellent hydrolysis resistance, mechanical strength, and heat resistance.

[0075] The shear strength, tensile strength, elongation at break, and impermeability of Examples 1 and 4 are superior to those of Example 5; the shear strength, tensile strength, elongation at break, and impermeability of Examples 6 and 7 are superior to those of Example 8. This may be because asbestos fibers have a higher aspect ratio than hollow glass beads, allowing them to interact with more molecules of other raw materials in the sealant, thereby enhancing the strength of the sealant; and the higher aspect ratio of asbestos fibers facilitates the expulsion of moisture from the sealant, thus reducing the impact of moisture in the sealant on the sealant and improving the sealant's hydrolysis resistance.

[0076] The shear strength, tensile strength, elongation at break, and impermeability of Examples 1 and 10-11 are superior to those of Examples 9 and 12; the shear strength, tensile strength, elongation at break, and impermeability of Examples 1 and 9-12 are superior to those of Examples 13-15. This may be because carbon black and calcium carbonate in the sealant raw materials play a toughening and reinforcing role, while the lubricating effect of talc promotes the dispersion between the sealant raw materials. When the mass ratio of calcium carbonate, talc, and carbon black is 2:(1-3):2, the compatibility of calcium carbonate, talc, and carbon black is optimal. However, when the talc content is low, the dispersion effect between the sealant raw materials is poor; when the talc content is high, the reinforcing effect of the filler on the sealant is poor; when the calcium carbonate content is low or insufficient, the toughness of the sealant may decrease; when the carbon black content is insufficient, the strength of the sealant decreases. When calcium carbonate and carbon black are used in combination, the sealant has good strength and toughness, resulting in excellent shear strength, tensile strength, and elongation at break.

[0077] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A lightweight car body sealant, characterized in that, By weight, it comprises the following components: 140-180 parts of silane-modified polymer; Plasticizer 60-90 parts; 250-350 parts of filler; 4-10 parts of thixotropic agent; UV protectant 0.5-3 parts; Light stabilizer 0.5-3 parts; Heat stabilizer 0.5-3 parts; 3-10 parts of dehydrating agent; 3-8 parts of silane coupling agent; 1-3 parts of curing agent; The silane-modified polymer is a silane-terminated polyether polymer or a silane-modified polyurethane polymer. The filler comprises 20-40 parts of organic bentonite, 20-40 parts of zinc oxide, 20-50 parts of aluminum hydroxide, and 190-220 parts of filler A; wherein, filler A comprises 30-60 parts by weight of hollow glass beads and 160 parts by weight of filler B, wherein filler B is calcium carbonate, talc, and carbon black in a mass ratio of 2:(0.5-4):

2. The dehydrating agent is vinyltrimethoxysilane or vinyltriethoxysilane; The heat stabilizer is at least one of hindered phenolic antioxidants and phosphite antioxidants.

2. The lightweight car body sealant according to claim 1, characterized in that, The silane-terminated polyether polymers are Kaneka's S203H, S303H, SAX260, SAX750, GENIOSIL® STP-E15, and STP-E35; the silane-modified polyurethane polymers are AGC's SX3430E, SX6735D, and S888E; and Momentive's SPUR+* 1015, SPUR+* 1012, SPUR+* 3030, and SPUR+* 3040.

3. The lightweight car body sealant according to claim 1, characterized in that, The plasticizer is at least one of phthalate compounds and polyether polyols; the thixotropic agent is at least one of polyamide wax, hydrogenated castor oil, and silica.

4. The lightweight car body sealant according to claim 1, characterized in that, The light stabilizer is a hindered amine light stabilizer; the UV stabilizer is a benzotriazole UV stabilizer.

5. The lightweight car body sealant according to claim 1, characterized in that, The curing agent is a chelated tin catalyst.

6. The lightweight car body sealant according to claim 1, characterized in that, The silane coupling agent is an aminosilane selected from γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-ureapropyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, and γ-glycidyl etheryltrimethoxysilane.

7. A method for preparing the lightweight car body sealant according to any one of claims 1-6, characterized in that, Includes the following steps: The silane-modified polymer, plasticizer, filler, thixotropic agent, UV stabilizer, light stabilizer and heat stabilizer are mixed under a vacuum of not less than 980 mbar and a stirring speed of 600-800 rpm / min. Then heat to 110-130℃ and dehydrate for 120-140 minutes under a vacuum of not less than 980mbar and a stirring speed of 300-600rpm / min. Next, the temperature is lowered to 40-45℃, a dehydrating agent is added, and the mixture is stirred for 20-30 minutes at a speed of 250-300 rpm / min; a silane coupling agent is added, and the mixture is stirred for 25-35 minutes at a speed of 250-300 rpm / min; a curing agent is added, and the mixture is stirred for 25-35 minutes at a vacuum of not less than 980 mbar and a speed of 250-300 rpm / min to prepare a lightweight car body sealant.

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