Hydrogenated polybutadiene modified vinyl siloxane as well as preparation method and application thereof

Abstract

The invention belongs to the field of sealants, and relates to hydrogenated polybutadiene modified vinyl siloxane as well as a preparation method and application thereof. The structure of the hydrogenated polybutadiene modified vinyl siloxane is shown as a formula (1). The sealing silica gel obtained by adopting the hydrogenated polybutadiene modified vinyl siloxane as shown in the formula (1) as matrix resin not only has good air-blocking, water-blocking and acid-resisting properties in a short time, but also basically does not decline in air-blocking, water-blocking and acid-resisting properties after long-time high-temperature operation. R1R2R3SiO [(Me2SiO) a (MeViSiO) b (CH2CH2CH2CH2) c (CH2CH (CH2CH3)) dO] nSiR1R2R3 Formula (1)

Description

Technical Field

[0001] This invention belongs to the field of sealants, specifically relating to a hydrogenated polybutadiene-modified vinylsiloxane, its preparation method, and its application. Background Technology

[0002] Fuel cells, as a new generation of clean energy, generate electricity through the reaction of hydrogen and oxygen, and are most widely used in proton exchange membrane fuel cells (PEMFCs). PEMFCs supply hydrogen-containing fuel gas to the anode electrode and oxygen-containing oxidizing gas to the cathode electrode in a separate manner. If insufficient isolation leads to mixing of the two gases, it can cause a decrease in power generation efficiency and create an acidic environment during operation. Therefore, to prevent fuel gas leakage, most fuel cells require the use of sealants to form gaskets, which are placed between the bipolar plates and the membrane electrode assembly. These gaskets are directly exposed to acidic liquid solutions and humid air, requiring them to possess high gas and water barrier properties, acid resistance, and the ability to withstand temperature cycling and compressive stress to achieve a superior sealing effect.

[0003] Silicone rubber is widely used in gasket manufacturing due to its excellent mechanical stability and resistance to high and low temperatures, as well as good electrical insulation, elasticity, and coolant resistance, which meet the sealing requirements of most hydrogen fuel cells. However, the large Si-O bond length and helical molecular structure of silicone rubber result in high water vapor permeability, leading to poor barrier properties against gases and water vapor. Furthermore, silicone rubber has poor acid resistance; acidic conditions catalyze its hydrolysis, causing the -Si-O-Si bonds to hydrolyze into -Si-OH, resulting in the breakage of the main chain and cross-linking points. Summary of the Invention

[0004] The primary objective of this invention is to overcome the shortcomings of existing silicone rubbers, such as poor gas and water barrier properties and poor acid resistance, and to provide a hydrogenated polybutadiene-modified vinylsiloxane that still exhibits good gas and water barrier properties and acid resistance after long-term operation in a high-temperature environment.

[0005] A second objective of this invention is to provide a method for preparing the above-mentioned hydrogenated polybutadiene-modified vinylsiloxane.

[0006] The structure of the hydrogenated polybutadiene-modified vinylsiloxane provided by the present invention is shown in formula (1);

[0007] R1R2R3SiO[(Me2SiO) a (MeViSiO) b (CH2CH2CH2CH2) c (CH2CH(CH2CH3)) d O] nSiR1ˋR2ˋR3ˋ

[0008] Equation (1)

[0009] In formula (1), R1, R2, R1ˋ and R2ˋ are each independently C1-C8 alkyl groups, R3 and R3ˋ are each independently C1-C8 alkyl groups or vinyl groups, a is any integer from 1 to 1000, b is any integer from 1 to 1000, c and d are integers and the sum of c and d is any integer from 2 to 800, and n is any integer from 1 to 500.

[0010] In a preferred embodiment, in formula (1), R1, R2, R1ˋ and R2ˋ are each independently C1-C5 alkyl groups, and R3 and R3ˋ are each independently C1-C5 alkyl groups or vinyl groups.

[0011] In a preferred embodiment, in formula (1), a is any integer from 100 to 1000, b is any integer from 100 to 1000, c and d are integers and the sum of c and d is any integer from 10 to 300, and n is any integer from 10 to 200.

[0012] The method for preparing hydrogenated polybutadiene-modified vinylsiloxane provided by this invention includes:

[0013] S1: Hydroxyl-terminated hydrogenated polybutadiene and hydroxyl-terminated vinyl silicone oil undergo a first condensation reaction in the presence of a catalyst to obtain a condensation product containing hydroxyl-terminated hydrogenated polybutadiene modified vinyl silicone resin.

[0014] S2: The condensation product is reacted with silanol in a second condensation reaction to obtain hydrogenated polybutadiene-modified vinylsiloxane.

[0015] In a preferred embodiment, in step S1, the first condensation reaction is carried out by adding the catalyst dropwise to the hydroxyl-terminated hydrogenated polybutadiene and stirring to mix it evenly, while adding the hydroxyl-terminated vinyl silicone oil to the reaction system in batches at the condensation reaction temperature. After all the hydroxyl-terminated vinyl silicone oil has been added, the reaction is stirred and the reaction is continued to obtain the condensation product containing the hydroxyl-terminated hydrogenated polybutadiene modified vinyl silicone resin.

[0016] In a preferred embodiment, in step S1, the condensation reaction temperature is 100–140°C.

[0017] In a preferred embodiment, in step S1, the hydroxyl-terminated vinyl silicone oil is added to the reaction system in 2 to 5 portions, with each portion added every 30 to 60 minutes.

[0018] In a preferred embodiment, in step S1, the stirring reaction time after all the terminal hydroxyl vinyl silicone oil is added is 1 to 5 hours.

[0019] In a preferred embodiment, in step S1, the number-average molecular weight of the hydroxyl-terminated hydrogenated polybutadiene is 500 to 10,000.

[0020] In a preferred embodiment, in step S1, the vinyl content of the hydroxyl-terminated vinyl silicone oil is 0.01% to 10%, and the hydroxyl content is 0.1% to 20%.

[0021] In a preferred embodiment, in step S1, the molar ratio of the hydroxyl-terminated hydrogenated polybutadiene to the hydroxyl-terminated vinyl silicone oil is (0.001-5):1.

[0022] In a preferred embodiment, in step S2, the silanol is selected from at least one of trimethylsilanol, triethylsilanol, and dimethylvinylsilanol.

[0023] In a preferred embodiment, in step S2, the molar ratio of the silanol to the hydroxyl-terminated vinyl silicone oil is (0.01-1):1.

[0024] In a preferred embodiment, in step S2, the conditions for the second condensation reaction include a temperature of 100–140°C and a time of 1–5 h.

[0025] A third objective of this invention is to provide hydrogenated polybutadiene-modified vinylsiloxane prepared by the above method.

[0026] A fourth objective of this invention is to provide the application of the above-mentioned hydrogenated polybutadiene-modified vinylsiloxane as a sealant resin.

[0027] After in-depth and extensive research, the inventors of this invention discovered that modifying silicone sealant with hydrogenated polybutadiene generally improves the gas barrier, water barrier and acid resistance of silicone sealant in the short term. However, after long-term high-temperature operation, the gas barrier, water barrier and acid resistance will decrease significantly. In contrast, the silicone sealant obtained by using the hydrogenated polybutadiene-modified vinylsiloxane shown in formula (1) as the main resin not only has good gas barrier, water barrier and acid resistance in the short term, but also does not decrease significantly after long-term high-temperature operation. Attached Figure Description

[0028] Figure 1 To prepare the HLBH-P2000-Si-100 obtained in Example 1 1 H-NMR spectrum;

[0029] Figure 2 To prepare the HLBH-P2000-Si-200 obtained in Example 2 1 H-NMR spectrum;

[0030] Figure 3To prepare the HLBH-P2000-Si-300 obtained in Example 3 1 H-NMR spectrum;

[0031] Figure 4 To prepare the HLBH-P3000-Si-400 obtained in Example 4 1 H-NMR spectrum;

[0032] Figure 5 To prepare the HLBH-P3000-Si-500 obtained in Example 5 1 H-NMR spectrum;

[0033] Figure 6 To prepare the HLBH-P3000-Si-600 obtained in Example 6 1 H-NMR spectrum. Detailed Implementation

[0034] The structure of the hydrogenated polybutadiene-modified vinylsiloxane provided by this invention is shown in formula (1):

[0035] R1R2R3SiO[(Me2SiO) a (MeViSiO) b (CH2CH2CH2CH2) c (CH2CH(CH2CH3)) d O] n SiR1`R2`R3`

[0036] Equation (1)

[0037] In formula (1), R1, R2, R1', and R2' are each independently C1-C8 alkyl groups, preferably each independently C1-C5 alkyl groups. R3 and R3' are each independently C1-C8 alkyl or vinyl groups, preferably each independently C1-C5 alkyl or vinyl groups. Specific examples of the C1-C5 alkyl groups include, but are not limited to: methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, tert-pentyl, or neopentyl. When R3 and / or R3' are vinyl groups, the acid resistance is better, the water vapor transmission rate is lower, and the permanent compression set is smaller. a is any integer from 1 to 1000, preferably any integer from 100 to 1000, such as 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, or any value between them. b is any integer from 1 to 1000, preferably any integer from 100 to 1000, such as 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, or any value between them. c and d are integers, and the sum of c and d is any integer from 2 to 800, preferably any integer from 10 to 300, such as 10, 20, 50, 80, 100, 150, 200, 250, 300, or any value between them. n is any integer from 1 to 500, preferably any integer from 10 to 200, such as 10, 20, 50, 80, 100, 120, 150, 180, 200, or any value between them.

[0038] The method for preparing hydrogenated polybutadiene-modified vinylsiloxane provided by this invention includes:

[0039] S1: Hydroxyl-terminated hydrogenated polybutadiene and hydroxyl-terminated vinyl silicone oil undergo a first condensation reaction in the presence of a catalyst to obtain a condensation product containing hydroxyl-terminated hydrogenated polybutadiene modified vinyl silicone resin.

[0040] S2: The condensation product is reacted with silanol in a second condensation reaction to obtain hydrogenated polybutadiene-modified vinylsiloxane.

[0041] In this invention, in step S1, the first condensation reaction can be carried out, for example, by mixing hydroxyl-terminated hydrogenated polybutadiene, hydroxyl-terminated vinyl silicone oil, and catalyst in any order, and then reacting them under condensation reaction conditions. In a preferred embodiment, the first condensation reaction is carried out by adding the catalyst dropwise to the hydroxyl-terminated hydrogenated polybutadiene and stirring until uniformly mixed, while simultaneously adding the hydroxyl-terminated vinyl silicone oil to the reaction system in batches at the condensation reaction temperature. After all the hydroxyl-terminated vinyl silicone oil has been added, the reaction is continued with stirring to obtain the condensation product containing hydroxyl-terminated hydrogenated polybutadiene-modified vinyl silicone resin. The preferred condensation reaction temperature is 100–140°C, such as 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, or any value between them. The hydroxyl-terminated vinyl silicone oil is added to the reaction system in 2 to 5 portions (e.g., 2, 3, 4, or 5 times), with each addition occurring every 30 to 60 minutes (e.g., 30, 35, 40, 45, 50, 55, or 60 minutes). The preferred stirring time after all the hydroxyl-terminated vinyl silicone oil has been added is 1 to 5 hours, such as 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, or any value between these times.

[0042] In this invention, in step S1, the hydroxyl-terminated hydrogenated polybutadiene can be any existing hydrogenated polybutadiene with hydroxyl-terminated ends, and its number-average molecular weight is preferably 500 to 50000, such as 500, 1000, 2000, 5000, 8000, 10000, 15000, 20000, 25000, 30000, 35000, 40000, 45000, 50000 or any value between them.

[0043] In this invention, in step S1, the hydroxyl-terminated vinyl silicone oil can be any existing vinyl silicone oil containing hydroxyl groups, with a vinyl content of 0.01% to 10% (e.g., 0.01%, 0.05%, 1%, 2%, 4%, 6%, 8%, 10% or any value therebetween), and a hydroxyl content of 0.1% to 20% (e.g., 0.1%, 0.5%, 1%, 2%, 4%, 6%, 8%, 10%, 12%, 14%, 16%, 18%, 20% or any value therebetween).

[0044] In this invention, in step S1, the molar ratio of the hydroxyl-terminated hydrogenated polybutadiene to the hydroxyl-terminated vinyl silicone oil is preferably (0.001 to 1):1, such as 0.001:1, 0.05:1, 0.08:1, 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, or any value between them.

[0045] In this invention, specific examples of the silanol in step S2 include, but are not limited to, at least one of trimethylsilanol, triethylsilanol, and dimethylvinylsilanol.

[0046] In this invention, in step S2, the molar ratio of the silanol to the hydroxyl-terminated vinyl silicone oil is preferably (0.01 to 1):1, such as 0.01:1, 0.05:1, 0.08:1, 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1 or any value between them.

[0047] In this invention, in step S2, the conditions for the second condensation reaction include a temperature preferably of 100 to 140°C, such as 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C or any value between them; and a time preferably of 1 to 5 hours, such as 1 hour, 2 hours, 3 hours, 4 hours, 5 hours or any value between them.

[0048] The low water vapor permeability acid-resistant silicone sealant raw material provided by this invention comprises, by weight parts:

[0049] 5-90 parts of hydrogenated polybutadiene-modified vinylsiloxane;

[0050] Vinyl silicone oil 0-20 parts;

[0051] 1-20 parts of hydrogen-containing silicone oil;

[0052] Platinum catalyst 0.05-5 parts;

[0053] Inhibitor 0.01–0.5 parts;

[0054] 5-30 parts of reinforcing agent.

[0055] In this invention, the vinyl silicone oil is preferably selected from at least one of vinyl-terminated polydimethylsiloxane, vinyl-terminated polymethylphenylsiloxane, methyl-terminated polysiloxane with vinyl side chains, and vinyl-terminated polysiloxane with vinyl side chains. The vinyl content in the vinyl silicone oil is preferably 0.01% to 5%, such as 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.8%, 1%, 2%, 3%, 4%, 5%, or any value between these values. The vinyl silicone oil has a viscosity of 50 to 50,000 cSt at 25°C, such as 50 cSt, 100 cSt, 500 cSt, 1000 cSt, 2000 cSt, 3000 cSt, 4000 cSt, 5000 cSt, 6000 cSt, 7000 cSt, 8000 cSt, 10000 cSt, 20000 cSt, 30000 cSt, 40000 cSt, 50000 cSt, or any value between them.

[0056] In this invention, the hydrogen-containing silicone oil serves as a crosslinking agent and can be selected from at least one of end-group hydrogen-containing silicone oil, side-chain hydrogen-containing silicone oil, and silicone oil containing hydrogen on both ends. Preferably, the Si-H content in the hydrogen-containing silicone oil is 0.1–1.6 wt%, such as 0.1 wt%, 0.3 wt%, 0.5 wt%, 0.8 wt%, 1 wt%, 1.2 wt%, 1.4 wt%, 1.6 wt%, or any value between these values. The hydrogen-containing silicone oil can be selected from at least one of Runhe Organosilicon's RH-H502*, RH-H503*, RH-H512*, RH-H8*, RH-LHC-1, RH-LHC-2, etc.

[0057] In this invention, the platinum catalyst specifically refers to a class of catalysts that use platinum as the main active component and can catalyze hydrosilylation reactions. It can be applied to silicone sealants, and specific examples include, but are not limited to, at least one of the following: β-dicarbonyl platinum, phosphine platinum, platinum(O)-olefin complexes, nitroene platinum, platinum(O)-alkenylsiloxane complexes, platinum(O)-alkenylamino complexes, and platinum-phosphite complexes. Specific examples of the β-dicarbonyl platinum can be, but are not limited to, platinum acetylacetonate. Specific examples of the phosphine platinum can be, but are not limited to, cis-dichlorobis(tributylphosphine)platinum and / or cis-dichlorobis(dimethylphenylphosphine)platinum. Specific examples of the platinum(O)-olefin complex can be, but are not limited to, trimethylmethylcyclopentadiene platinum. Specific examples of the nitroene platinum can be, but are not limited to, tetrakis(1-phenyl-3-hexyltriazine)platinum. Specific examples of the platinum(O)-alkenylsiloxane complex include, but are not limited to, platinum(O)-vinyltetramethyldisiloxane complex and / or platinum(O)-divinyltetraphenyldisiloxane complex. Specific examples of the platinum(O)-vinylamino complex include, but are not limited to, tetrakis(1-phenyl-3-hexyltriazine)platinum. Specific examples of the platinum-phosphite complex include, but are not limited to, tetrakis(triphenylphosphine)platinum (Pt(PPh3)4). Furthermore, the platinum content of the platinum catalyst is preferably 1000–5000 ppm, such as 1000 ppm, 1100 ppm, 1500 ppm, 2000 ppm, 3000 ppm, 4000 ppm, 5000 ppm, or any value between these values.

[0058] In this invention, the inhibitor specifically refers to a class of substances that can poison platinum catalysts and render them inactive at low temperatures. This is a type of additive commonly used in existing one-component silicone sealants, and specific examples include, but are not limited to, at least one of alkynyl alcohols, maleate esters, and fumarate esters. Specific examples of alkynyl alcohols include, but are not limited to, methylbutyninol and / or ethynylcyclohexanol. Specific examples of maleate esters include, but are not limited to, at least one of dimethyl maleate, dipropyl maleate, and diethyl maleate. Specific examples of fumarate esters include, but are not limited to, dimethyl fumarate and / or diethyl fumarate.

[0059] In this invention, the reinforcing agent is used to improve tensile strength. Specific examples of the reinforcing agent include, but are not limited to, at least one of fumed silica (fumed silica), fused spherical silica, and glass fiber powder, preferably fumed silica. Fumed silica exhibits good dispersibility and a superior reinforcing effect compared to other fillers, especially hydrophobic fumed silica, such as Evonik's R972 and Wacker's H-21, which can increase the thixotropy of the sealant and also improve the tensile strength of the cured product.

[0060] In this invention, the additives can be selected based on the desired performance of the single-component silicone sealant composition, and specific examples include, but are not limited to, at least one of accelerators, reinforcing agents, silane coupling agents, thixotropic agents, and antioxidants. For example, thixotropic agents, such as organobentonite, polyamide wax, and nano-calcium carbonate, can be added to achieve appropriate rheological properties of the sealant, considering dispensing characteristics. Antioxidants can be added to consider weather resistance and heat resistance.

[0061] The method for preparing a low-water-vapor-permeability, acid-resistant single-component silicone sealant provided by this invention uses the above-mentioned raw materials as raw materials, and specifically includes the following steps:

[0062] S1. Add hydrogenated polybutadiene-modified vinylsiloxane, vinyl silicone oil, hydrogen-containing silicone oil, inhibitor and reinforcing agent to a stirred tank in sequence, and stir under vacuum until well mixed.

[0063] S2. Reduce the temperature inside the stirring vessel to below 30°C, then add platinum catalyst and stir under vacuum to obtain a low water vapor permeability and acid-resistant silicone sealant for hydrogen fuel cells.

[0064] In this invention, the stirring vessel used in steps S1 and S2 is preferably a double planetary stirring vessel. The stirring speed is preferably 30 to 60 rpm, such as 30, 40, 50, 60 rpm or any value between them; the dispersion disc speed is preferably 200 to 400 rpm, such as 200 rpm, 250 rpm, 300 rpm, 350 rpm, 400 rpm or any value between them.

[0065] The present invention will be described in detail below through embodiments.

[0066] Preparation Example 1

[0067] S1: Take 226.5g of hydroxyl-terminated hydrogenated polybutadiene (Krasol HLBH-P2000, number average molecular weight 2000) and place it in a reaction vessel. Add dibutyltin dilaurate catalyst dropwise and stir to mix evenly. The stirring speed is controlled at 100rpm. The amount of dibutyltin dilaurate catalyst is 0.1wt% of the total mass of hydroxyl-terminated hydrogenated polybutadiene and hydroxyl-terminated vinyl silicone oil. Then weigh 100g of hydroxyl-terminated vinyl silicone oil (purchased from Anhui Mingyi Silicon Industry Co., Ltd., vinyl content 2.3%, hydroxyl content 6.4%) and add it in 4 portions at 120℃, one portion every 40min. After all the oil is added, continue the reaction for 2h to obtain the condensation product of hydroxyl-terminated hydrogenated polybutadiene modified vinyl silicone resin.

[0068] S2: Add 15g of trimethylsilanol to the condensation product and continue stirring at 120℃ for 2h to obtain silanyl-terminated hydrogenated polybutadiene-modified vinylsiloxane, denoted as HLBH-P2000-Si-100.

[0069] The reaction processes in steps S1 and S2 are as follows:

[0070] Step S1:

[0071]

[0072] Chemical shift of HLBH-P2000-Si-100: 1 H-NMR (CDCl3), δ (ppm): 0.83ppm and 1.26ppm are the peaks of methyl and methylene groups of hydrogenated polybutadiene, 0.1ppm is the peak of silanyl group in hydroxyvinyl silicone oil, 5.8ppm~6.0ppm is the peak of silyl ethylene double bond in hydroxyvinyl silicone oil, and 0.07ppm is the peak of silanyl group on trimethylsilanol. Furthermore, the hydroxyl group peak disappears on the NMR, indicating that the hydroxyl group has been completely reacted. Therefore, HLBH-P2000-Si-100 has the structure shown in formula (1), where R1, R2, R3, R1', R2', and R3' are methyl groups.

[0073] Preparation Example 2

[0074] Hydrogenated polybutadiene-modified vinylsiloxane was prepared according to the method provided in Preparation Example 1, except that in step S2, 22.4 g of triethylsilanol was added to the condensation product. Other conditions were the same as in Preparation Example 1, and silylacetic-terminated hydrogenated polybutadiene-modified vinylsiloxane was obtained, denoted as HLBH-P2000-Si-200.

[0075] Chemical shift of HLBH-P2000-Si-200: 1H-NMR (CDCl3), δ (ppm): 0.83ppm and 1.26ppm are the peaks of methyl and methylene groups of hydrogenated polybutadiene, 0.1ppm is the peak of silanyl methyl group in hydroxyvinyl silicone oil, 5.8ppm~6.0ppm is the peak of silyl ethylene double bond in hydroxyvinyl silicone oil, and 0.61ppm and 0.98ppm are the peaks of methyl and methylene groups on triethylsilanol. Furthermore, the hydroxyl group peak disappears on the NMR, indicating that the hydroxyl group has been completely reacted. Therefore, HLBH-P2000-Si-200 has the structure shown in formula (1), where R1, R2, R3, R1', R2', and R3' are ethyl groups.

[0076]

[0077] Preparation Example 3

[0078] Hydrogenated polybutadiene-modified vinyl siloxane was prepared according to the method provided in Preparation 1, except that in step S2, 16.4 g of dimethylvinylsilanol was added to the condensation product. Other conditions were the same as in Preparation Example 1, and silylmethyl vinyl-terminated hydrogenated polybutadiene-modified vinyl siloxane was obtained, denoted as HLBH-P2000-Si-300.

[0079] Chemical shift of HLBH-P2000-Si-300: 1 H-NMR (CDCl3), δ (ppm): 0.83ppm and 1.26ppm are the peaks of methyl and methylene groups in hydrogenated polybutadiene, 0.1ppm is the peak of silanyl methyl groups in hydroxyvinyl silicone oil, 5.8ppm to 6.0ppm are the peaks of silyl ethylene double bonds in hydroxyvinyl silicone oil, and 0.53ppm is the peak of silyl ethylene double bonds on dimethylvinylsilanol. Furthermore, the hydroxyl peak disappears on the NMR, indicating that the hydroxyl group has been completely reacted. Therefore, HLBH-P2000-Si-300 has the structure shown in formula (1), where R1, R2, R1', and R2' are methyl groups, and R3 and R3' are vinyl groups.

[0080]

[0081] Preparation Example 4

[0082] Hydrogenated polybutadiene-modified vinylsiloxane was prepared according to the method provided in Preparation 1, except that in step S1, 334.8 g of hydroxyl-terminated hydrogenated polybutadiene (Krasol HLBH-P2000, number average molecular weight 3000) was used instead of hydroxyl-terminated hydrogenated polybutadiene (Krasol HLBH-P3000, number average molecular weight 3000), and the other conditions were the same as in Preparation Example 1, to obtain silanyl-terminated hydrogenated polybutadiene-modified vinylsiloxane, denoted as HLBH-P3000-Si-400.

[0083] Chemical shift of HLBH-P3000-Si-400: 1 H-NMR (CDCl3), δ (ppm): 0.83ppm and 1.26ppm are the peaks of methyl and methylene groups of hydrogenated polybutadiene, 0.1ppm is the peak of silanyl groups in hydroxyl vinyl silicone oil, 5.8ppm to 6.0ppm are the peaks of silyl ethylene double bonds in hydroxyl vinyl silicone oil, and 0.07ppm is the peak of silanyl groups on trimethylsilanol. Furthermore, the hydroxyl group peak disappears on the NMR, indicating that the hydroxyl group has been completely reacted. Therefore, HLBH-P3000-Si-400 has the structure shown in formula (1), where R1, R2, R3, R1ˋ, R2ˋ, and R3ˋ are methyl groups.

[0084] Preparation Example 5

[0085] Hydrogenated polybutadiene-modified vinylsiloxane was prepared according to the method provided in Preparation Example 1, except that in step S1, 334.8 g of hydroxyl-terminated hydrogenated polybutadiene (Krasol HLBH-P2000, number average molecular weight 3000) was used instead of hydroxyl-terminated hydrogenated polybutadiene (Krasol HLBH-P3000, number average molecular weight 3000), and in step S2, 15 g of trimethylsilanol was used instead of 22.4 g of triethylsilanol. The remaining conditions were the same as in Preparation Example 1, and silanyl-terminated hydrogenated polybutadiene-modified vinylsiloxane was obtained, denoted as HLBH-P3000-Si-500.

[0086] Chemical shift of HLBH-P3000-Si-500: 1 H-NMR (CDCl3), δ (ppm): 0.83ppm and 1.26ppm are the peaks of methyl and methylene groups of hydrogenated polybutadiene, 0.1ppm is the peak of silanyl methyl group in hydroxyvinyl silicone oil, 5.8ppm~6.0ppm is the peak of silyl ethylene double bond in hydroxyvinyl silicone oil, and 0.61ppm and 0.98ppm are the peaks of methyl and methylene groups on triethylsilanol. Furthermore, the hydroxyl group peak disappears on the NMR, indicating that the hydroxyl group has been completely reacted. Therefore, HLBH-P3000-Si-500 has the structure shown in formula (1), where R1, R2, R3, R1ˋ, R2ˋ, and R3ˋ are ethyl groups.

[0087] Preparation Example 6

[0088] Hydrogenated polybutadiene-modified vinylsiloxane was prepared according to the method provided in Preparation Example 1, except that in step S1, 334.8 g of hydroxyl-terminated hydrogenated polybutadiene (Krasol HLBH-P2000, number average molecular weight 3000) was used instead of hydroxyl-terminated hydrogenated polybutadiene (Krasol HLBH-P3000, number average molecular weight 3000), and in step S2, 15 g of trimethylsilanol was used instead of 16.4 g of dimethylvinylsilanol. The remaining conditions were the same as in Preparation Example 1, and silanyl-terminated hydrogenated polybutadiene-modified vinylsiloxane was obtained, denoted as HLBH-P3000-Si-600.

[0089] Chemical shift of HLBH-P3000-Si-600: 1 H-NMR (CDCl3), δ (ppm): 0.83ppm and 1.26ppm are the peaks of methyl and methylene groups in hydrogenated polybutadiene, 0.1ppm is the peak of silanyl methyl groups in hydroxyvinyl silicone oil, 5.8ppm to 6.0ppm are the peaks of silyl ethylene double bonds in hydroxyvinyl silicone oil, and 0.53ppm is the peak of silyl ethylene double bonds on dimethylvinylsilanol. Furthermore, the hydroxyl peak disappears on the NMR, indicating that the hydroxyl group has been completely reacted. Therefore, HLBH-P3000-Si-600 has the structure shown in formula (1), where R1, R2, R1ˋ, and R2ˋ are methyl groups, and R3 and R3ˋ are vinyl groups.

[0090] Comparative Preparation Example 1

[0091] Hydrogenated polybutadiene-modified vinylsiloxane was prepared according to the method of Preparation Example 1, except that step S2 was not included, and the condensation product obtained in step S1 was directly used as the final product, denoted as D-HLBH-P2000-Si-100.

[0092] Example 1

[0093] 80 parts by weight of the hydrogenated polybutadiene-modified vinyl silicone resin HLBH-P2000-Si-100 obtained in Preparation Example 1, 16 parts by weight of side-chain vinyl silicone oil RH-Vi306, 7.8 parts by weight of hydrogen-containing silicone oil with a hydrogen content of 0.75 wt% (RH-H502* from Zhejiang Runhe Organosilicon New Material Co., Ltd., the same below), 0.05 parts by weight of diethyl maleate, 10 parts by weight of R972 hydrophobic fumed silica, and 0.5 parts by weight of silane coupling agent were added to a planetary mixer and vacuum stirred for 1 hour. Then, 0.5 parts by weight of platinum catalyst, i.e., Castel catalyst (3000 ppm), were added and vacuum stirred for 30 minutes to obtain a viscous sealant composition, which was then filled into a silicone tube for storage.

[0094] Example 2

[0095] 80 parts by weight of the hydrogenated polybutadiene-modified vinyl silicone resin HLBH-P2000-Si-200 obtained in Preparation Example 2, 16 parts by weight of side-chain vinyl silicone oil RH-Vi306, 7.8 parts by weight of hydrogen-containing silicone oil with a hydrogen content of 0.75 wt%, 0.05 parts by weight of diethyl maleate, 10 parts by weight of R972 hydrophobic fumed silica, and 0.5 parts by weight of silane coupling agent were added to a planetary mixer and vacuum stirred for 1 hour. Then, 0.6 parts by weight of platinum catalyst, i.e., Castel catalyst (3000 ppm), were added and vacuum stirred for 30 minutes to obtain a viscous sealant composition, which was then filled into a silicone tube for storage.

[0096] Example 3

[0097] 80 parts by weight of the hydrogenated polybutadiene-modified vinyl silicone resin HLBH-P2000-Si-300 obtained in Preparation Example 3, 16 parts by weight of the side-chain vinyl silicone oil RH-Vi306, 9.2 parts by weight of hydrogen-containing silicone oil with a hydrogen content of 0.75 wt%, 0.05 parts by weight of diethyl maleate, 10 parts by weight of R972 hydrophobic fumed silica, and 0.5 parts by weight of silane coupling agent were added to a planetary mixer and vacuum stirred for 1 hour. Then, 0.7 parts by weight of platinum catalyst, i.e., Castel catalyst (3000 ppm), were added and vacuum stirred for 30 minutes to obtain a viscous sealant composition, which was then filled into a silicone tube for storage.

[0098] Example 4

[0099] 80 parts by weight of the hydrogenated polybutadiene-modified vinyl silicone resin HLBH-P3000-Si-400 obtained in Preparation Example 4, 16 parts by weight of side-chain vinyl silicone oil RH-Vi306, 6.2 parts by weight of hydrogen-containing silicone oil with a hydrogen content of 0.75 wt%, 0.05 parts by weight of diethyl maleate, 15 parts by weight of R972 hydrophobic fumed silica, and 0.5 parts by weight of silane coupling agent were added to a planetary mixer and vacuum stirred for 1 hour. Then, 0.5 parts by weight of platinum catalyst, i.e., Castel catalyst (3000 ppm), were added and vacuum stirred for 30 minutes to obtain a viscous sealant composition, which was then filled into a silicone tube for storage.

[0100] Example 5

[0101] 80 parts by weight of the hydrogenated polybutadiene-modified vinyl silicone resin HLBH-P3000-Si-500 obtained in Preparation Example 5, 16 parts by weight of side-chain vinyl silicone oil RH-Vi306, 6.2 parts by weight of hydrogen-containing silicone oil with a hydrogen content of 0.75 wt%, 0.05 parts by weight of diethyl maleate, 10 parts by weight of R972 hydrophobic fumed silica, and 0.5 parts by weight of silane coupling agent were added to a planetary mixer and vacuum stirred for 1 hour. Then, 0.6 parts by weight of platinum catalyst, i.e., Castel catalyst (3000 ppm), were added and vacuum stirred for 30 minutes to obtain a viscous sealant composition, which was then filled into a silicone tube for storage.

[0102] Example 6

[0103] 80 parts by weight of the hydrogenated polybutadiene-modified vinyl silicone resin HLBH-P3000-Si-600 obtained in Preparation Example 6, 16 parts by weight of side-chain vinyl silicone oil RH-Vi306, 7.5 parts by weight of hydrogen-containing silicone oil with a hydrogen content of 0.75 wt%, 0.05 parts by weight of diethyl maleate, 10 parts by weight of R972 hydrophobic fumed silica, and 0.5 parts by weight of silane coupling agent were added to a planetary mixer and vacuum stirred for 1 hour. Then, 0.7 parts by weight of platinum catalyst, i.e., Castel catalyst (3000 ppm), were added and vacuum stirred for 30 minutes to obtain a viscous sealant composition, which was then filled into a silicone tube for storage.

[0104] Comparative Example 1

[0105] 80 parts by weight of end-chain vinyl silicone oil RH-Vi302, 16 parts by weight of side-chain vinyl silicone oil RH-Vi306, 5.8 parts by weight of hydrogen-containing silicone oil with a hydrogen content of 0.75 wt%, 0.05 parts by weight of diethyl maleate, 10 parts by weight of R972 hydrophobic fumed silica, and 0.5 parts by weight of silane coupling agent were added to a planetary mixer and vacuum stirred for 1 hour. Then, 0.5 parts by weight of platinum catalyst, i.e., Castel catalyst (3000 ppm), were added and vacuum stirred for 30 minutes to obtain a viscous sealant composition, which was then filled into a silicone tube for storage.

[0106] Comparative Example 2

[0107] 80 parts by weight of side-chain vinyl silicone oil RH-Vi315, 16 parts by weight of side-chain vinyl silicone oil RH-Vi306, 7.5 parts by weight of hydrogen-containing silicone oil with a hydrogen content of 0.75wt%, 0.05 parts by weight of diethyl maleate, 10 parts by weight of R972 hydrophobic fumed silica, and 0.5 parts by weight of silane coupling agent were added to a planetary mixer and vacuum stirred for 1 hour. Then, 0.5 parts by weight of platinum catalyst, i.e., Castel catalyst (3000ppm), were added and vacuum stirred for 30 minutes to obtain a viscous sealant composition, which was then filled into a silicone tube for storage.

[0108] Comparative Example 3

[0109] A viscous sealant composition was prepared according to the method of Example 1, except that the hydrogenated polybutadiene-modified vinyl silicone resin HLBH-P2000-Si-100 obtained in Preparation Example 1 was replaced by the same weight of hydroxyl-terminated hydrogenated polybutadiene-modified vinyl silicone resin D-HLBH-P2000-Si-100 obtained in Comparative Preparation Example 1, and the other conditions were the same as in Preparation Example 1, to obtain a reference viscous sealant composition.

[0110] Comparative Example 4

[0111] A viscous sealant composition was prepared according to the method of Example 1, except that the hydrogenated polybutadiene-modified vinyl silicone resin HLBH-P2000-Si-100 obtained in Preparation Example 1 was replaced by a mixture of hydroxyl-terminated hydrogenated polybutadiene (Krasol HLBH-P2000) and hydroxyl-terminated vinyl silicone oil at a mass ratio of 226.5:100 in the same parts by weight. The other conditions were the same as in Preparation Example 1, and a reference viscous sealant composition was obtained.

[0112] Comparative Example 5

[0113] A viscous sealant composition was prepared according to the method of Example 1, except that the hydrogenated polybutadiene modified vinyl silicone resin HLBH-P2000-Si-100 obtained in Preparation Example 1 was replaced with the same amount of side-chain vinyl silicone oil RH-Vi306, and the other conditions were the same as in Preparation Example 1, to obtain a reference viscous sealant composition.

[0114] Test case

[0115] The samples from the examples and comparative examples were compared and tested using the following method:

[0116] (1) Viscosity: According to the test method of GB / T 2794-2022, the viscosity was tested using a Brookfield viscometer at room temperature. Specific test conditions: A 52# rotor was used, and the viscosity was measured by rotating at 1 rpm for 10 minutes. The results are shown in Table 1.

[0117] (2) Hardness: According to the test method of GB / T 531.1-2008, the single-component silicone sealant was made into a cylinder with a thickness of 2 mm, and the hardness was tested using a Shore A hardness tester. The results are shown in Table 1.

[0118] (3) Water vapor transmission rate: According to the test method of GB / T 26253-2010, a circular disc corresponding to the cup ring was prepared by curing a single-component silicone sealant at 120℃ for 60 min. The water vapor transmission rate was tested at a temperature of 60±0.6℃ and a relative humidity of 90±2%. The water vapor transmission rate was calculated. After placing the disc sample at 90℃ for 30 days, the water vapor transmission rate was tested again at a temperature of 60±0.6℃ and a relative humidity of 90±2%. In the specific testing process of water vapor transmission rate, a disc was placed in the test chamber, with one side being a low-humidity chamber and the other a high-humidity chamber. The high-humidity chamber was filled with water vapor and the relative humidity was 90±2%. The temperature of the test chamber was controlled at 60±0.6℃. Due to the humidity difference between the two sides of the sample, water vapor permeated from the high-humidity chamber through the disc to the low-humidity chamber. The water vapor was then transported by the carrier gas to the infrared detector, generating a certain amount of electrical signal. After the experiment reached a stable state, the water vapor transmission rate of the sample was calculated from the output electrical signal. The results are shown in Table 1.

[0119] (4) Acid Resistance Test: Based on the phenomenon that silicone rubber will age and degrade over time in an acidic environment, which is expressed as weight loss, an experiment was conducted. A rectangular sample with a length of 50 mm, a width of 40 mm, and a thickness of 0.5 mm was prepared. The mass of the sample before immersion in the acid solution was recorded as W0. The sample was immersed in a strongly acidic solution with a pH of 3.35, simulating a fuel cell, and then placed in a high-low temperature alternating aging test chamber. The cyclic temperature was -5℃ to 90℃, with a temperature increase / decrease rate of 1℃ / min. After 50 / 200 cycles, the sample was removed, thoroughly washed with deionized water, and dried at room temperature for 24 hours. The mass of the sample was then recorded as Wn (n is the number of cycles). The weight change (acid resistance) was calculated using the following formula:

[0120] Weight change rate (acid resistance): W(%) = [(Wn-W0) / W0] × 100%. The results are shown in Table 1.

[0121] (5) Permanent Compression Deformation: According to the test method of GB / T 7759.1-2015, a cylinder with a thickness of 6.3mm±0.3mm and a diameter of 13mm±0.3mm was prepared by curing a single-component silicone sealant at 120℃ for 18h. The cylinder and the restrainer were placed in a compression fixture and placed at a compression ratio of 25% and a temperature of 120℃ for 24h. Then, the cylinder was removed and placed at room temperature for 60min to cool completely before being released. After placing it at room temperature for another 60min, the thickness of the cylinder was measured, and the permanent compression deformation was calculated according to the following formula: C=[(To-Ti) / (To-Tn)]×100%, where C is the compression deformation (unit: %), Tn is the restrainer thickness (unit: mm), To is the sample thickness before the experiment (unit: mm), and Ti is the sample thickness after the experiment (unit: mm). The results are shown in Table 1.

[0122] Table 1

[0123]

[0124] As can be seen from the results in Table 1, compared with the traditional organosilicon system, the sealing silicone obtained by using hydrogenated polybutadiene-modified vinylsiloxane provided by the present invention as the main resin does not show a significant increase in viscosity and the hardness remains at around A30. However, the acid resistance is significantly improved and the water vapor transmission rate is significantly reduced. Furthermore, after long-term high-temperature operation, the acid resistance and water vapor transmission rate do not decrease significantly.

[0125] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A hydrogenated polybutadiene-modified vinylsiloxane, characterized in that, The structure of the hydrogenated polybutadiene-modified vinylsiloxane is shown in formula (1); R1R2R3SiO[(Me2SiO) a (MeViSiO) b (CH2CH2CH2CH2) c (CH2CH(CH2CH3)) d O] n SiR1ˋR2ˋR3ˋ Equation (1) In formula (1), R1, R2, R1ˋ and R2ˋ are each independently C1-C8 alkyl groups, R3 and R3ˋ are each independently C1-C8 alkyl groups or vinyl groups, a is any integer from 1 to 1000, b is any integer from 1 to 1000, c and d are integers and the sum of c and d is any integer from 2 to 800, and n is any integer from 1 to 500.

2. The hydrogenated polybutadiene-modified vinylsiloxane according to claim 1, characterized in that, In formula (1), R1, R2, R1ˋ and R2ˋ are each independently C1-C5 alkyl groups, and R3 and R3ˋ are each independently C1-C5 alkyl groups or vinyl groups.

3. The hydrogenated polybutadiene-modified vinylsiloxane according to claim 1, characterized in that, a is any integer between 100 and 1000, b is any integer between 100 and 1000, c and d are integers and the sum of c and d is any integer between 10 and 300, and n is any integer between 10 and 200.

4. A method for preparing hydrogenated polybutadiene-modified vinylsiloxane, characterized in that, The method includes: S1: Hydroxyl-terminated hydrogenated polybutadiene and hydroxyl-terminated vinyl silicone oil undergo a first condensation reaction in the presence of a catalyst to obtain a condensation product containing hydroxyl-terminated hydrogenated polybutadiene modified vinyl silicone resin. S2: The condensation product is reacted with silanol in a second condensation reaction to obtain hydrogenated polybutadiene-modified vinylsiloxane.

5. The method for preparing hydrogenated polybutadiene-modified vinylsiloxane according to claim 4, characterized in that, In step S1, the first condensation reaction is carried out by adding the catalyst dropwise to the hydroxyl-terminated hydrogenated polybutadiene and stirring to mix it evenly. At the same time, the hydroxyl-terminated vinyl silicone oil is added to the reaction system in batches at the condensation reaction temperature. After all the hydroxyl-terminated vinyl silicone oil has been added, the reaction is stirred and the reaction is continued to obtain the condensation product containing hydroxyl-terminated hydrogenated polybutadiene modified vinyl silicone resin. Preferably, the condensation reaction temperature is 100–140°C; Preferably, the hydroxyl-terminated vinyl silicone oil is added to the reaction system in 2 to 5 portions, one portion every 30 to 60 minutes; Preferably, the stirring reaction time after all the hydroxyl-terminated vinyl silicone oil is added is 1 to 5 hours.

6. The method for preparing hydrogenated polybutadiene-modified vinylsiloxane according to claim 4, characterized in that, In step S1, the number-average molecular weight of the hydroxyl-terminated hydrogenated polybutadiene is 500 to 50,000. Preferably, the hydroxyl-terminated vinyl silicone oil has a vinyl content of 0.01% to 10% and a hydroxyl content of 0.1% to 20%. Preferably, the molar ratio of the hydroxyl-terminated hydrogenated polybutadiene to the hydroxyl-terminated vinyl silicone oil is (0.001-1):

1.

7. The method for preparing hydrogenated polybutadiene-modified vinylsiloxane according to claim 4, characterized in that, In step S2, the silanol is selected from at least one of trimethylsilanol, triethylsilanol, and dimethylvinylsilanol; Preferably, the molar ratio of the silanol to the hydroxyl-terminated vinyl silicone oil is (0.01-1):

1.

8. The method for preparing hydrogenated polybutadiene-modified vinylsiloxane according to claim 4, characterized in that, In step S2, the conditions for the second condensation reaction include a temperature of 100–140°C and a time of 1–5 h.

9. Hydrogenated polybutadiene-modified vinylsiloxane prepared by the method according to any one of claims 4 to 8.

10. The use of the hydrogenated polybutadiene-modified vinylsiloxane according to any one of claims 1 to 3 and 9 as a sealant resin.

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