CN116536029A - A kind of high weather resistance silicone sealant for automobile and preparation method thereof - Google Patents

Abstract

The invention relates to the field of sealants, in particular to a highly weather-resistant silicone sealant for automobiles and a preparation method thereof. Branched silicone rubber is used as the base rubber, and allyl double bonds and silicon in the synthesized allylated phenolic resin are used to Hydrosilylation of rubber side groups to achieve chemical grafting; MXene is functionalized, and small molecular substances containing benzene rings and phenolic hydroxyl groups are grown on MXene in situ; biphenyl liquid crystals are added; carbon nanotubes are added to further synergize MXene Improve the weather resistance of the sealant; modify the carbon nanotubes, impregnate the carbon nanotubes, deposit porous polyethersulfone on the surface of the carbon nanotubes, and prepare porous polyethersulfone-based carbon nanotubes with a bamboo-like structure, and then In situ synthesis of molybdenum disulfide, the obtained composite carbon nanotubes are hybrids of carbon nanotubes and molybdenum disulfide, and then the surface of the composite carbon nanotubes is modified with amino-terminated hyperbranched polyamides to obtain branched polyamide-modified composites. carbon nanotubes.

Description

A kind of high weather resistance silicone sealant for automobile and preparation method thereof

technical field

The invention relates to the field of sealants, in particular to a highly weather-resistant silicone sealant for automobiles and a preparation method thereof.

Background technique

In the existing automobile production process, the car body is often treated with sealant, which has the effect of sealing and antirust after baking; because polyurethane sealant has good elasticity, good adhesion, good wear resistance, and high mechanical strength. and other characteristics, the existing automobile industry mostly uses polyurethane sealant as the colloid for bonding the windshield and sealing the car body, but it is easy to cause foaming or glue cracking during the baking process, which affects the aesthetics and sealing of the car body Due to the poor heat resistance and weather resistance, when it is used to seal between the car glass and the window frame, it is easy to exist in the high temperature and high humidity season or under the strong light in summer when it rains or black matter will flow down with the water when washing the car. The problem.

Contents of the invention

The purpose of the present invention is to provide a high weather resistance silicone sealant for automobiles and a preparation method thereof, so as to solve the problems in the prior art.

In order to solve the above technical problems, the present invention provides the following technical solutions:

A preparation method for high-weather-resistant silicone sealant for automobiles, comprising the following steps:

S1: Mix branched silicone rubber, dimethyl silicone oil, and functionalized MXene, and stir in vacuum to obtain component A glue;

S2: Mix branched silicone rubber, dimethyl silicone oil, branched polyamide-modified composite carbon nanotubes, 3-aminopropyltriethoxysilane, methyltributanoximinosilane, and a catalyst, and stir in vacuum to obtain B component glue;

S3: Mix component A glue and component B glue in a vacuum at a mass ratio of 6:1 to obtain a highly weather-resistant silicone sealant for automobiles.

Further, the working conditions of the vacuum stirring are: the degree of vacuum is -0.095MPa, and the time is 20-30min.

Further, the catalyst is an organotin catalyst.

Further, in parts by mass, the content of each component in the component A glue is: 184-192 parts of branched silicone rubber, 67-78 parts of dimethyl silicone oil, and 5-10 parts of functionalized MXene.

Further, in terms of parts by mass, the content of each component in the B component glue is: 5-8 parts of branched silicone rubber, 10-12 parts of dimethyl silicone oil, 4 parts of branched polyamide-modified composite carbon nanotubes -6 parts, 8-10 parts of 3-aminopropyl triethoxysilane, 5-8 parts of methyl tributanoximinosilane, 0.08-0.1 parts of catalyst.

Further, the preparation of branched silicone rubber comprises the following steps:

1) Mix phenolic resin, potassium hydroxide, and n-butanol, heat up to 75-80°C and stir evenly, cool down to 55-60°C, add allyl bromide, heat up to 75-80°C and keep for 6 hours, add deionized water to The eluate is neutral, spin off the solvent, heat up to 145-150°C and vacuum dry for 6 hours to obtain allyl etherified phenolic resin;

2) Blend allyl etherified phenolic resin and xylene, add Karstedt catalyst, raise the temperature to 85-90°C under the protection of argon, add the mixture of hydrogen-containing silicone rubber and xylene, keep it warm for 22-24h, spin off solvent to obtain branched silicone rubber.

Further, the preparation of functionalized MXene includes the following steps:

(1) Mix lithium fluoride and hydrochloric acid, add MAX, stir at 38°C for 46-48 hours, wash with hydrochloric acid and lithium chloride successively for 3-5 times, wash with deionized water until the pH value is 6, and store in a nitrogen atmosphere Ultrasonic stirring in an ice bath for 1 h, centrifugation at a speed of 3500 rpm for 1 h, and freeze-drying to obtain MXene nanosheets;

(2) In a nitrogen atmosphere, mix acetone, 1,6-dibromohexane, cyanobiphenol, and potassium carbonate, heat up to 70-75°C for 8-10 hours, spin evaporate, add deionized water, and filter with suction , recrystallized in acetonitrile, and dried to obtain a liquid crystal intermediate; under a nitrogen atmosphere, mix acetonitrile, liquid crystal intermediates, 2-methylimidazole, and MXene nanosheets, stir ultrasonically for 1 hour, keep warm at 55-60°C for 8 hours, and spin evaporate , adding ether for extraction, and suction filtration to obtain functionalized MXene.

Further, the preparation of branched polyamide-modified composite carbon nanotubes comprises the following steps:

A. Soak carbon nanotubes in hydrochloric acid and stir for 10-30min, rinse with distilled water until neutral; transfer to a mixture of polyethersulfone, N,N-dimethylacetamide, and isopropanol for 5-6h, Then transfer to deionized water and soak for 5-6h, after drying, obtain pretreated carbon nanotubes;

B. Mix thiourea, ammonium molybdate tetrahydrate, and deionized water for 15-20 minutes, add pretreated carbon nanotubes, transfer to a polytetrafluoroethylene-lined reaction kettle, and keep warm for 22-24 hours at 210-220°C , and then washed with distilled water for 3-5 times, and dried to obtain composite carbon nanotubes;

C. Soak the composite carbon nanotubes in hydrochloric acid for 20-30min, take it out, add thionyl chloride, stir at 70°C for 22-24h, reduce pressure, add N,N-dimethylformamide, and disperse ultrasonically at 60°C 20-30min, add pyridine, N,N-dimethylformamide, 8g hyperbranched polyamide, keep warm at 18-25℃ for 22-24h, filter and wash until neutral, dry and grind to obtain branched polyamide modification composite carbon nanotubes.

Further, the mass volume ratio of composite carbon nanotubes, pyridine, and hyperbranched polyamide is 5g:8g:0.5mL.

Beneficial effects of the present invention:

The invention provides a high-weather-resistant silicone sealant for automobiles and a preparation method thereof. The components and processes are adjusted so that the prepared silicone sealant has excellent sealing performance, high temperature resistance, acid and alkali resistance, and ultraviolet resistance. It meets the requirements of silicone sealants for automobiles.

In the present invention, branched silicone rubber is used as the base rubber, and chemical grafting is realized through the addition of allyl double bonds in the synthesized allylated phenolic resin and the side groups of silicone rubber to achieve chemical grafting, thereby improving the toughness and high temperature of silicone rubber. Stability. Compared with silicone rubber, the multi-reaction sites of branched silicone rubber are beneficial to improve the compatibility of silicone rubber with MXene and carbon nanotubes.

Improve the sealability and UV resistance of silicone rubber by adding MXene, functionalize MXene, and in-situ grow biphenyl liquid crystals containing benzene rings and phenolic hydroxyl groups on MXene, using mesogens and MXene The interaction between them forms a highly ordered structure. While solving the dispersion uniformity of MXene in the rubber base, it can also obtain a toughening effect and improve the mechanical strength of the silicone sealant. Through the mesogen containing phenyl and biphenyl It can effectively absorb ultraviolet rays and endow silicone sealant with higher anti-ultraviolet performance.

By adding carbon nanotubes to further synergize MXene to improve the weather resistance of the sealant; by modifying the carbon nanotubes, impregnating the carbon nanotubes, depositing porous polyethersulfone on the surface of the carbon nanotubes, and preparing a bamboo-like structure Porous polyethersulfone-based carbon nanotubes, and then synthesize molybdenum disulfide in situ, and the composite carbon nanotubes obtained are hybrids of carbon nanotubes and molybdenum disulfide, and then use amino-terminated hyperbranched polyamide to synthesize the composite carbon nanotubes. Surface modification to obtain branched polyamide-modified composite carbon nanotubes, which can effectively improve the wear resistance and UV resistance of silicone sealants, and at the same time make the carbon nanotubes permanently and firmly bonded to the base rubber, thereby avoiding the high-temperature and high-humidity season. Or the problem of "black water flowing" under the strong light in summer can greatly improve the weather resistance of the silicone sealant, thereby prolonging the service life of the silicone sealant.

Implementation

The technical solutions in the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Apparently, the described embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

It should be noted that if there are directional indications such as up, down, left, right, front, back in the embodiment of the present invention, the directional indications are only used to explain the relative relationship between parts in a certain posture. When the positional relationship, movement conditions, etc., if the specific posture changes, the directional indication will also change accordingly. In addition, the technical solutions of the various embodiments can be combined with each other, but it must be based on the realization of those skilled in the art. When the combination of technical solutions is contradictory or cannot be realized, it should be considered that the combination of technical solutions does not exist , nor within the scope of protection required by the present invention.

The technical solutions of the present invention will be described in further detail below in conjunction with specific examples. It should be understood that the following examples are only used to explain the present invention, and are not intended to limit the present invention.

Embodiment 1: a kind of preparation method of high weather resistance silicone sealant for automobiles, comprising the following steps:

S1: Mix branched silicone rubber, dimethyl silicone oil, and functionalized MXene, and stir in vacuum to obtain component A glue;

In terms of parts by mass, the content of each component in the A component glue is: 184 parts of branched silicone rubber, 67 parts of dimethyl silicone oil, and 5 parts of functionalized MXene;

The preparation of branched silicone rubber comprises the following steps:

1) Mix 2.5g of phenolic resin, 0.25g of potassium hydroxide, and 50mL of n-butanol, heat up to 75°C and stir evenly, cool down to 55°C and add 10mL of allyl bromide, heat up to 75°C for 6 hours, add deionized water to The eluate is neutral, spin off the solvent, heat up to 150°C and vacuum dry for 6 hours to obtain allyl etherified phenolic resin;

2) Blend 1g of allyl etherified phenolic resin and 1g of xylene, add 1mg of Karstedt catalyst, raise the temperature to 90°C under the protection of argon, add 3g of hydrogen-containing silicone rubber and 3g of xylene mixed solution, keep the temperature for 22h, spin off Solvent, obtain branched silicone rubber;

The preparation of functionalized MXene includes the following steps:

(1) Dissolve 1g of lithium fluoride in 20mL9mmol/L hydrochloric acid, add 1gMAX (titanium aluminum carbide powder), stir at 38°C for 46h, wash with hydrochloric acid and lithium chloride three times in turn, and wash with deionized water to pH The value is 6, ultrasonically stirred in an ice bath for 1 h in a nitrogen atmosphere, centrifuged at a speed of 3500 rpm for 1 h, and freeze-dried to obtain MXene nanosheets;

(2) Mix 40mL of acetone, 3.25g of 1,6-dibromohexane, 1.5g of cyanobiphenol, and 1.2g of potassium carbonate in a nitrogen atmosphere, raise the temperature to 70°C and keep it warm for 10h, spin evaporate, add deionized water, Suction filtration, recrystallization in acetonitrile, and drying to obtain liquid crystal intermediates; under nitrogen atmosphere, mix 40mL acetonitrile, 1.5g liquid crystal intermediates, 2.5g 2-methylimidazole, 2.5g MXene nanosheets, ultrasonically stir for 1h, at 55℃ Insulated for 8 hours, rotary steamed, added ether for extraction, and suction filtered to obtain functionalized MXene;

S2: Mix branched silicone rubber, dimethyl silicone oil, branched polyamide-modified composite carbon nanotubes, 3-aminopropyltriethoxysilane, methyltributanoximinosilane, and a catalyst, and stir in vacuum to obtain B component glue;

In terms of parts by mass, the content of each component in the B component glue is: 5 parts of branched silicone rubber, 10 parts of dimethyl silicone oil, 4 parts of branched polyamide-modified composite carbon nanotubes, 3-aminopropyl 8 parts of triethoxysilane, 5 parts of methyl tributylketoxime silane, 0.08 part of catalyst; the catalyst is an organotin catalyst;

The preparation of the branched polyamide modified composite carbon nanotubes comprises the following steps:

A. Soak 1g of carbon nanotubes in hydrochloric acid and stir for 10min, rinse with distilled water until neutral; transfer to a mixture of 0.2g of polyethersulfone, 5mL N,N-dimethylacetamide, and 0.05g of isopropanol for 5h , then transferred to deionized water and soaked for 5h, after drying, the pretreated carbon nanotubes were obtained;

B. Mix 3.95g of thiourea, 3.4g of ammonium molybdate tetrahydrate, and 25mL of deionized water for 15 minutes, add 3g of pretreated carbon nanotubes, transfer to a polytetrafluoroethylene-lined reactor, and keep warm at 210°C for 24 hours , and then washed with distilled water for 3-5 times, and dried to obtain composite carbon nanotubes;

C. Soak 1g of composite carbon nanotubes in hydrochloric acid for 20min, take it out, add 16mL of thionyl chloride, 1mL of N,N-dimethylformamide, stir at 70°C for 22h, reduce pressure, add 6mL of N,N-dimethylformamide In amide, ultrasonically disperse at 60°C for 20min, add 0.1mL pyridine, 20mL N,N-dimethylformamide, 1.6g hyperbranched polyamide, keep warm at 18°C for 24h, filter and wash until neutral, dry, and grind to obtain Branched polyamide modified composite carbon nanotubes;

S3: Mix component A glue and component B glue in a vacuum at a mass ratio of 6:1 to obtain a highly weather-resistant silicone sealant for automobiles.

Embodiment 2: a kind of preparation method of high weather resistance silicone sealant for automobiles, comprising the following steps:

S1: Mix branched silicone rubber, dimethyl silicone oil, and functionalized MXene, and stir in vacuum to obtain component A glue;

In terms of parts by mass, the content of each component in the A component glue is: 187 parts of branched silicone rubber, 72 parts of dimethyl silicone oil, and 6 parts of functionalized MXene;

The preparation of branched silicone rubber comprises the following steps:

1) Mix 2.5g of phenolic resin, 0.25g of potassium hydroxide, and 50mL of n-butanol, heat up to 78°C and stir evenly, cool down to 58°C and add 10mL of allyl bromide, heat up to 78°C for 6 hours, add deionized water to The eluate is neutral, spin off the solvent, heat up to 150°C and vacuum dry for 6 hours to obtain allyl etherified phenolic resin;

2) Blend 1g of allyl etherified phenolic resin and 1g of xylene, add 1mg of Karstedt catalyst, raise the temperature to 90°C under the protection of argon, add 3g of hydrogen-containing silicone rubber and 3g of xylene mixed solution, keep the temperature for 23h, spin off Solvent, obtain branched silicone rubber;

The preparation of functionalized MXene includes the following steps:

(1) Dissolve 1g of lithium fluoride in 20mL9mmol/L hydrochloric acid, add 1gMAX (titanium aluminum carbide powder), stir at 38°C for 47h, wash with hydrochloric acid and lithium chloride for 4 times, and wash with deionized water to pH The value is 6, ultrasonically stirred in an ice bath for 1 h in a nitrogen atmosphere, centrifuged at a speed of 3500 rpm for 1 h, and freeze-dried to obtain MXene nanosheets;

(2) Mix 40mL of acetone, 3.25g of 1,6-dibromohexane, 1.5g of cyanobiphenol, and 1.2g of potassium carbonate in a nitrogen atmosphere, raise the temperature to 72°C and keep it warm for 9h, spin evaporate, add deionized water, Suction filtration, recrystallization in acetonitrile, and drying to obtain liquid crystal intermediates; under nitrogen atmosphere, mix 40mL acetonitrile, 1.5g liquid crystal intermediates, 2.5g 2-methylimidazole, 2.5g MXene nanosheets, and ultrasonically stir for 1h, at 58°C Insulated for 8 hours, rotary steamed, added ether for extraction, and suction filtered to obtain functionalized MXene;

S2: Mix branched silicone rubber, dimethyl silicone oil, branched polyamide-modified composite carbon nanotubes, 3-aminopropyltriethoxysilane, methyltributanoximinosilane, and a catalyst, and stir in vacuum to obtain B component glue;

In terms of parts by mass, the content of each component in the B component glue is: 7 parts of branched silicone rubber, 11 parts of dimethyl silicone oil, 5 parts of branched polyamide-modified composite carbon nanotubes, 3-aminopropyl 9 parts of triethoxysilane, 6 parts of methyl tributylketoxime silane, 0.09 part of catalyst; the catalyst is an organotin catalyst;

The preparation of the branched polyamide modified composite carbon nanotubes comprises the following steps:

A. Soak 1g of carbon nanotubes in hydrochloric acid and stir for 20min, rinse with distilled water until neutral; h, then transferred to deionized water and soaked for 5.5h, after drying, to obtain pretreated carbon nanotubes;

B. Mix 3.95g of thiourea, 3.4g of ammonium molybdate tetrahydrate, and 25mL of deionized water for 18 minutes, add 3g of pretreated carbon nanotubes, transfer to a polytetrafluoroethylene-lined reactor, and keep warm at 215°C for 23 hours , and then washed 4 times with distilled water, and dried to obtain composite carbon nanotubes;

C. Soak 1g of composite carbon nanotubes in hydrochloric acid for 25min, take it out, add 16mL of thionyl chloride, 1mL of N,N-dimethylformamide, stir at 70°C for 23h, reduce pressure, add 6mL of N,N-dimethylformamide In amide, ultrasonically disperse at 60°C for 25min, add 0.1mL pyridine, 20mL N,N-dimethylformamide, 1.6g hyperbranched polyamide, keep warm at 20°C for 23h, filter and wash until neutral, dry, and grind to obtain Branched polyamide modified composite carbon nanotubes;

S3: Mix component A glue and component B glue in a vacuum at a mass ratio of 6:1 to obtain a highly weather-resistant silicone sealant for automobiles.

Embodiment 3: a kind of preparation method of high weather resistance silicone sealant for automobiles, comprising the following steps:

S1: Mix branched silicone rubber, dimethyl silicone oil, and functionalized MXene, and stir in vacuum to obtain component A glue;

In terms of parts by mass, the content of each component in the A component glue is: 192 parts of branched silicone rubber, 78 parts of dimethyl silicone oil, and 10 parts of functionalized MXene;

The preparation of branched silicone rubber comprises the following steps:

1) Mix 2.5g of phenolic resin, 0.25g of potassium hydroxide, and 50mL of n-butanol, heat up to 80°C and stir evenly, cool down to 60°C and add 10mL of allyl bromide, heat up to 80°C for 6 hours, add deionized water to The eluate is neutral, spin off the solvent, heat up to 150°C and vacuum dry for 6 hours to obtain allyl etherified phenolic resin;

2) Blend 1g of allyl etherified phenolic resin and 1g of xylene, add 1mg of Karstedt catalyst, raise the temperature to 90°C under the protection of argon, add 3g of hydrogen-containing silicone rubber and 3g of xylene mixed solution, keep the temperature for 24h, spin off Solvent, obtain branched silicone rubber;

The preparation of functionalized MXene includes the following steps:

(1) Dissolve 1g of lithium fluoride in 20mL9mmol/L hydrochloric acid, add 1gMAX (titanium aluminum carbide powder), stir at 38°C for 48h, wash with hydrochloric acid and lithium chloride for 5 times, and wash with deionized water to pH The value is 6, ultrasonically stirred in an ice bath for 1 h in a nitrogen atmosphere, centrifuged at a speed of 3500 rpm for 1 h, and freeze-dried to obtain MXene nanosheets;

(2) Mix 40mL of acetone, 3.25g of 1,6-dibromohexane, 1.5g of cyanobiphenol, and 1.2g of potassium carbonate in a nitrogen atmosphere, raise the temperature to 75°C and keep it for 8 hours, spin evaporate, add deionized water, Suction filtration, recrystallization in acetonitrile, and drying to obtain liquid crystal intermediates; under nitrogen atmosphere, mix 40mL acetonitrile, 1.5g liquid crystal intermediates, 2.5g 2-methylimidazole, 2.5g MXene nanosheets, ultrasonically stir for 1h, at 60°C Insulated for 8 hours, rotary steamed, added ether for extraction, and suction filtered to obtain functionalized MXene;

S2: Mix branched silicone rubber, dimethyl silicone oil, branched polyamide-modified composite carbon nanotubes, 3-aminopropyltriethoxysilane, methyltributanoximinosilane, and a catalyst, and stir in vacuum to obtain B component glue;

In terms of parts by mass, the content of each component in the B component glue is: 8 parts of branched silicone rubber, 12 parts of dimethyl silicone oil, 6 parts of branched polyamide-modified composite carbon nanotubes, 3-aminopropyl 10 parts of triethoxysilane, 8 parts of methyl tributylketoxime silane, 0.1 part of catalyst; the catalyst is an organotin catalyst;

The preparation of the branched polyamide modified composite carbon nanotubes comprises the following steps:

A. Soak 1g of carbon nanotubes in hydrochloric acid and stir for 30min, rinse with distilled water until neutral; transfer to a mixture of 0.2g of polyethersulfone, 5mL of N,N-dimethylacetamide, and 0.05g of isopropanol for 6h , then transferred to deionized water for soaking for 6 hours, and dried to obtain pretreated carbon nanotubes;

B. Mix 3.95g of thiourea, 3.4g of ammonium molybdate tetrahydrate, and 25mL of deionized water for 20 minutes, add 3g of pretreated carbon nanotubes, transfer to a polytetrafluoroethylene-lined reactor, and keep warm at 220°C for 22 hours , and then washed 5 times with distilled water, and dried to obtain composite carbon nanotubes;

C. Soak 1g of composite carbon nanotubes in hydrochloric acid for 30min, take it out, add 16mL of thionyl chloride, 1mL of N,N-dimethylformamide, stir at 70°C for 24h, reduce pressure, and add 6mL of N,N-dimethylformamide In amide, ultrasonically disperse at 60°C for 30min, add 0.1mL pyridine, 20mL N,N-dimethylformamide, 1.6g hyperbranched polyamide, keep warm at 25°C for 22h, filter and wash until neutral, dry, and grind to obtain Branched polyamide modified composite carbon nanotubes;

S3: Mix component A glue and component B glue in a vacuum at a mass ratio of 6:1 to obtain a highly weather-resistant silicone sealant for automobiles.

Comparative Example 1: Taking Example 3 as the control group, the branched silicone rubber was replaced with hydrogen-containing silicone rubber, and other processes were normal.

Comparative Example 2: Taking Example 3 as the control group, the functionalized MXene was replaced with MXene, and other processes were normal.

Comparative Example 3: Taking Example 3 as the control group, the branched polyamide-modified composite carbon nanotubes were replaced with composite carbon nanotubes, and other processes were normal.

Comparative Example 4: Taking Example 3 as the control group, the branched polyamide-modified composite carbon nanotubes were replaced with carbon nanotubes, and other processes were normal.

Raw material source:

Dimethicone D493241, Phenolic Resin P195710, Lithium Fluoride L434127, 1,6-Dibromohexane D106541, 2-Methylimidazole M104839, 3-Aminopropyltriethoxysilane A107148, Methyltributanone Oxime Silane M192183, carbon nanotubes C313046, N,N-dimethylacetamide D108096, thiourea T400612, ammonium molybdate tetrahydrate A116378, thionyl chloride T110473, pyridine P111511, N,N-dimethylformamide D111999 : Aladdin Reagent; Polyethersulfone E1010: Dongguan Shenghao Plastic Raw Material Co., Ltd.; Organotin 1118-46-3: Tesco Chemical (Hubei) Co., Ltd.; Hyperbranched Polyamide HyperN102: Wuhan Hyperbranched Resin Technology Co., Ltd. ; Karstedt Catalyst 81032-58-8: Hubei Nona Technology Co., Ltd.; Allyl Bromide 106-95-6: Zouping Mingxing Chemical Co., Ltd.; Cyanobiphenol 19812-93-2: Hubei Wonder Chemical Co., Ltd.; MAX (titanium aluminum carbide powder) 196506-01-1: Fussman Technology (Beijing) Co., Ltd.; hydrogen-containing silicone rubber 70131-67-8: Wuhan Rongcan Biotechnology Co., Ltd.; potassium hydroxide, n-butanol, di Toluene, acetone, potassium carbonate, hydrochloric acid, acetonitrile, ether, isopropanol, analytical grade: Sinopharm reagent.

Performance test: carry out performance test to the sealant that embodiment 1-3, comparative example 1-4 make;

Tensile strength: 4g of silicone sealant is poured into Type I dumbbell Type I polytetrafluoroethylene plate, cured, and tested with a universal testing machine in accordance with GB/T 528-2009 at a temperature of 20°C and a tensile rate of 10mm /min;

UV resistance: Cured the sealant into 100mm, 100mm, 5mm samples, put them into QUV/SE accelerated weathering tester for aging test, tested by fluorescent ultraviolet/condensation cycle test method, the light source is UV-B lamp tube, a total of 12 The test conditions for each cycle are: light at 60°C×4h, condensation at 50°C×4h, light intensity of 0.71W/m ² , ultraviolet wavelength of 313nm; ΔEs is the change rate of tensile strength before and after aging treatment, and the unit is %;

Adhesion: Refer to the cross-cut method of GB/T9286-2021 to test the adhesion of the sealant. Use a 0.5mm aluminum plate as the substrate, coat the sealant on the aluminum plate to form a 100µm coating, and then test the adhesion of the sealant. Classification according to the area of cross-cut shedding: 0-no shedding, 1-no more than 5%, 2-more than 5%, no more than 15%, 3-more than 15%, no more than 35%, 4-more than 35%, no Greater than 65%, 5-the rest;

Heat resistance: Coat the sealant on a 0.5mm aluminum plate to form a 100µm coating as a sample, place it at 300°C for 100h, then test the adhesion of the sealant, and classify it according to the cross-cut peeling area: 0-no peeling , 1- not more than 5%, 2- more than 5%, not more than 15%, 3- more than 15%, not more than 35%, 4- more than 35%, not more than 65%, 5- other situations;

Solvent resistance, acid resistance, alkali resistance: pour silicone sealant on polyethylene film into 100mm, 100mm, 5mm samples, cure, put it in a wide-mouth glass bottle, inject 60mL xylene/10% into the bottle Sodium hydroxide/5% hydrochloric acid, cover the bottle cap and place it under standard conditions for 96 hours, observe whether the sample dissolves, the results are shown in Table 1;

Table 1: Example 1 Example 2 Example 3 Comparative example 1 Comparative example 2 Comparative example 3 Comparative example 4 Tensile strength (MPa) 5.1 5.3 5.6 3 3.3 3.6 3.2 UV resistance ΔEs 1.2 1.1 1 5.8 10.1 6.4 9.6 Adhesion (level) 0 0 0 2 2 1 2 Heat resistance (grade) 0 0 0 3 3 2 3 Solvent resistance no change no change no change / / / / acid resistance no change no change no change / / / / Alkali resistance no change no change no change / / / /

The invention provides a high-weather-resistant silicone sealant for automobiles and a preparation method thereof. The components and processes are adjusted so that the prepared silicone sealant has excellent sealing performance, high temperature resistance, acid and alkali resistance, and ultraviolet resistance. It meets the requirements of silicone sealants for automobiles.

Comparing Example 3 with Comparative Example 1, it can be seen that branched silicone rubber is used as the base rubber in the present invention, and the hydrosilylation of the allyl double bond in the synthesized allylated phenolic resin and the side group of the silicone rubber is used to realize Chemical grafting can improve the toughness and high temperature stability of silicone rubber. Compared with silicone rubber, the multi-reaction sites of branched silicone rubber are beneficial to improve the compatibility of silicone rubber with MXene and carbon nanotubes.

Comparing Example 3 with Comparative Example 2, it can be seen that by adding MXene to improve the sealability and UV resistance of silicone rubber, functionalize MXene, and grow small molecules containing benzene rings and phenolic hydroxyl groups in situ on MXene The substance biphenyl liquid crystal utilizes the interaction between mesogens and MXene to form a highly ordered structure. While solving the dispersion uniformity of MXene in the base rubber, it can obtain a toughening effect and improve the mechanical strength of the silicone sealant. The mesogens containing phenyl and biphenyl can effectively absorb ultraviolet rays, endowing the silicone sealant with higher anti-ultraviolet performance.

Comparing Example 3 with Comparative Example 3 and Comparative Example 4, it can be seen that by adding carbon nanotubes to further synergize MXene to improve the weather resistance of the sealant; by modifying the carbon nanotubes and impregnating the carbon nanotubes, Deposit porous polyethersulfone on the surface of carbon nanotubes to prepare porous polyethersulfone-based carbon nanotubes with imitation bamboo structure, and then synthesize molybdenum disulfide in situ to obtain composite carbon nanotubes, which are the hybridization of carbon nanotubes and molybdenum disulfide body, and then use amino-terminated hyperbranched polyamide to modify the surface of composite carbon nanotubes to obtain branched polyamide-modified composite carbon nanotubes, which can effectively improve the wear resistance and UV resistance of silicone sealants, and make carbon nanotubes The tube is permanently and firmly combined with the base glue, so as to avoid the problem of "black water" in the high temperature and high humidity season or under the strong light in summer, and greatly improve the weather resistance of the silicone sealant, thereby prolonging the use of the silicone sealant life.

The above is only an embodiment of the present invention, and does not limit the patent scope of the present invention. Under the inventive concept of the present invention, the equivalent structure transformation made by the specification of the present invention, or directly/indirectly used in other related All technical fields are included in the patent protection scope of the present invention.

Claims (5)

1. The preparation method of the high weather-resistant organic silicon sealant for the automobile is characterized by comprising the following steps of:

s1: mixing branched silicon rubber, dimethyl silicone oil and functionalized MXene, and stirring in vacuum to obtain component A rubber;

s2: mixing branched silicon rubber, dimethyl silicone oil, branched polyamide modified composite carbon nano tube, 3-aminopropyl triethoxysilane, methyl tributyl ketoxime silane and a catalyst, and stirring in vacuum to obtain a component B glue;

s3: the adhesive of the component A and the adhesive of the component B are prepared according to the mass ratio of 6:1, vacuum mixing to obtain the high weather-resistant organosilicon sealant for the automobile;

the adhesive comprises the following components in parts by weight: 184-192 parts of branched silicon rubber, 67-78 parts of dimethyl silicone oil and 5-10 parts of functionalized MXene;

the component adhesive comprises the following components in parts by weight: 5-8 parts of branched silicon rubber, 10-12 parts of dimethyl silicone oil, 4-6 parts of branched polyamide modified composite carbon nano tube, 8-10 parts of 3-aminopropyl triethoxysilane, 5-8 parts of methyl tributyl ketoxime silane and 0.08-0.1 part of catalyst;

the preparation of the branched silicone rubber comprises the following steps:

1) Mixing phenolic resin, potassium hydroxide and n-butanol, heating to 75-80 ℃ and stirring uniformly, cooling to 55-60 ℃, adding allyl bromide, heating to 75-80 ℃, preserving heat for 6 hours, adding deionized water until the eluate is neutral, spin-removing the solvent, heating to 145-150 ℃, and vacuum-pumping for 6 hours to obtain allyl etherified phenolic resin;

2) Blending allyl etherified phenolic resin and dimethylbenzene, adding a Karstedt catalyst, heating to 85-90 ℃ under the protection of argon, adding a mixed solution of hydrogen-containing silicone rubber and dimethylbenzene, preserving heat for 22-24 hours, and removing the solvent by screwing to obtain branched silicone rubber;

the preparation of the functionalized MXene comprises the following steps:

(1) Mixing lithium fluoride and hydrochloric acid, adding MAX, stirring at 38 ℃ for 46-48 hours, washing with hydrochloric acid and lithium chloride for 3-5 times in sequence, washing with deionized water until the pH value is 6, stirring with ice bath ultrasonic wave for 1 hour in nitrogen atmosphere, centrifuging at 3500rpm for 1 hour, and freeze-drying to obtain MXene nano-sheets;

(2) Mixing acetone, 1, 6-dibromohexane, cyano diphenol and potassium carbonate in a nitrogen atmosphere, heating to 70-75 ℃, preserving heat for 8-10h, steaming in a rotary mode, adding deionized water, filtering, recrystallizing in acetonitrile, and drying to obtain a liquid crystal intermediate; mixing acetonitrile, a liquid crystal intermediate, 2-methylimidazole and MXene nano-sheets in a nitrogen environment, ultrasonically stirring for 1h, preserving heat for 8h at 55-60 ℃, performing rotary evaporation, adding diethyl ether for extraction, and performing suction filtration to obtain functionalized MXene;

the preparation of the branched polyamide modified composite carbon nano tube comprises the following steps:

A. soaking carbon nanotube in hydrochloric acid, stirring for 10-30min, and washing with distilled water to neutrality; transferring to a mixed solution of polyethersulfone, N-dimethylacetamide and isopropanol, soaking for 5-6 hours, transferring to deionized water, soaking for 5-6 hours, and drying to obtain a pretreated carbon nanotube;

B. mixing thiourea, ammonium molybdate tetrahydrate and deionized water, stirring for 15-20min, adding pretreated carbon nanotubes, transferring into a reaction kettle with polytetrafluoroethylene as a lining, preserving heat for 22-24h at 210-220 ℃, washing with distilled water for 3-5 times, and drying to obtain composite carbon nanotubes;

C. soaking the composite carbon nano tube in hydrochloric acid for 20-30min, taking out, adding thionyl chloride, stirring at 70 ℃ for 22-24h, decompressing, adding into N, N-dimethylformamide, performing ultrasonic dispersion at 60 ℃ for 20-30min, adding pyridine, N-dimethylformamide and 8g of hyperbranched polyamide, preserving heat at 18-25 ℃ for 22-24h, performing suction filtration, washing to be neutral, drying and grinding to obtain the branched polyamide modified composite carbon nano tube.

2. The method for preparing the high weather-resistant organosilicon sealant for the automobile according to claim 1, wherein the working conditions of vacuum stirring are as follows: vacuum degree is-0.095 MPa, and time is 20-30min.

3. The method for preparing the high weather-resistant organosilicon sealant for automobiles according to claim 1, wherein the catalyst is an organotin catalyst.

4. The preparation method of the high weather-resistant organosilicon sealant for the automobile, according to claim 1, is characterized in that in the preparation of the branched polyamide modified composite carbon nanotube, the mass volume ratio of the composite carbon nanotube, pyridine and hyperbranched polyamide is 5g:8g:0.5mL.

5. A highly weatherable silicone sealant for automobiles, characterized by being processed by the preparation method according to any one of claims 1 to 4.